TITLE 35: ENVIRONMENTAL PROTECTION

SUBTITLE C: WATER POLLUTION

CHAPTER II: ENVIRONMENTAL PROTECTION AGENCY

PART 370

ILLINOIS RECOMMENDED STANDARDS FOR SEWAGE WORKS

SUBPART A: INTRODUCTION

Section

370.100 Purpose

370.110 Scope and Applicability

370.115 Incorporations by Reference

SUBPART B: ENGINEERING REPORTS, PLANS AND SPECIFICATIONS

Section

370.200 General

370.210 Engineering Report

370.211 Design Flows

370.220 Detailed Engineering Plan Drawings Format

370.230 Specifications to Accompany Detailed Engineering Plan Drawings

370.240 Revisions to Approved Plans and Specifications

370.250 Operation During Construction

370.260 Engineers Seal

SUBPART C: DESIGN OF SEWERS

Section

370.300 General Considerations

370.310 Design Basis

370.320 Details of Design and Construction

370.330 Manholes

370.340 Sewers in Relation to Streams

370.350 Protection of Water Supplies

SUBPART D: SEWAGE PUMPING STATIONS

Section

370.400 General

370.410 Design

370.420 Suction-Lift Pump Stations

370.430 Submersible Pump Stations - Special Considerations

370.440 Alarm Systems

370.450 Emergency Operation

370.460 Instructions and Equipment

370.470 Force Mains

SUBPART E: SEWAGE TREATMENT WORKS

Section

370.500 Plant Location

370.510 Quality of Effluent

370.520 Design

370.530 Plant Details

370.540 Plant Outfalls

370.550 Essential Facilities

370.560 Safety

370.570 Laboratory

SUBPART F: PRELIMINARY TREATMENT

Section

370.600 General Considerations

370.610 Screening Devices

370.620 Grit Removal Facilities

370.630 Pre-Aeration

SUBPART G: SETTLING

Section

370.700 General Considerations

370.710 Design Considerations

370.720 Sludge and Scum Removal

370.730 Protection and Service Facilities

370.740 Imhoff Tanks

370.750 Septic Tank - Tile System

SUBPART H: SLUDGE PROCESSING, STORAGE AND DISPOSAL

Section

370.800 General

370.810 Process Selection

370.820 Sludge Thickening

370.830 Anaerobic Sludge Digestion

370.840 Aerobic Sludge Digestion

370.845 High pH Stabilization

370.850 Sludge Pumps and Piping

370.860 Sludge Dewatering

370.870 Sludge Storage and Disposal

SUBPART I: BIOLOGICAL TREATMENT

Section

370.900 Trickling Filters

370.910 Rotating Biological Contactors (Repealed)

370.915 Rotating Biological Contactors

370.920 Activated Sludge

370.930 Waste Stabilization Ponds and Aerated Lagoons

370.940 Intermittent Sand Filtration for Secondary Treatment

SUBPART J: DISINFECTION

Section

370.1000 General

370.1010 Disinfection Process Selection

370.1020 Chlorine Disinfection

370.1021 Dechlorination

370.1022 Ultraviolet Disinfection

370.1030 Chlorine Gas Supply (Repealed)

370.1040 Piping and Connections (Repealed)

370.1050 Housing (Repealed)

370.1060 Respiratory Protection Equipment (Repealed)

370.1070 Application of Chlorine (Repealed)

370.1080 Sampling and Testing

SUBPART K: TERTIARY FILTRATION

Section

370.1100 Applicability

370.1110 Type

370.1120 High Rate Filtration

370.1130 Low Rate Intermittent or Periodically Dosed Sand Filters

SUBPART L: NUTRIENT REMOVAL

Section

370.1200 Phosphorus Removal by Chemical Treatment

370.1210 Ammonia Control

APPENDIX A Table No. 1 - Resident Occupancy Criteria

APPENDIX B Table No. 2 - Commonly Used Quantities of Sewage Flows From

Miscellaneous Type Facilities

APPENDIX C Table No. 3 - Air Test Table for Sanitary Sewer Leakage

Testing*

APPENDIX D Figure No. 1 - Design of Sewers - Ratio of Peak Flow to

Daily Average Flow

APPENDIX E Figure No. 2 - Primary Settling

APPENDIX F Figure No. 3 - B.O.D. Removal Single Stage Trickling Filter

Units Including Post Settling - No Recirculation Included

APPENDIX G Figure No. 4 - Break Tank Sketch for Potable Water Supply

Protection

APPENDIX H Old Section Numbers Referenced (Repealed)

AUTHORITY: Implementing Sections 4 and 39 and authorized by Section 39 of

the Environmental Protection Act [415 ILCS 5/4 and 39].

SOURCE: Adopted at 4 Ill. Reg. 14, p. 224, effective March 31, 1980;

codified at 8 Ill. Reg. 19430; recodified at 18 Ill. Reg. 6375; amended at

21 Ill. Reg. 12444, effective August 28, 1997.

NOTE: In this Part, superscript numbers or letters are denoted by

parentheses; subscript are denoted by brackets.

SUBPART A: INTRODUCTION

The purpose of this Part is to establish criteria for the design and

preparation of plans and specifications for wastewater collection and

treatment systems.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) These design criteria apply to conventional design concepts for

wastewater collection and treatment systems. Where

non-conventional concepts or approaches to collection and

treatment, particularly for very small systems, are being

considered, the Agency should be contacted for any design guidance

that may be available.

b) In evaluating plans and specifications for new processes, the

Agency will consider the specific information submitted with the

design in accordance with the provisions of Section 370.520(b) for

situations involving new process evaluation.

c) These criteria are intended to establish limiting values for those

aspects of plans and specifications which the Agency evaluates and

to promote, as far as practicable, uniformity of practice

throughout the State. For projects with a design flow average of

over 100 million gallons per day (mgd), the application of

specific design parameters in these criteria should be evaluated

on a unit-by-unit basis to insure optimum design performance and

cost effective construction. In applying these criteria,

consideration must be given to the characteristics (including

current water quality) and uses of the receiving stream in order

to insure compliance with the applicable regulations of the

Illinois Pollution Control Board (hereinafter "IPCB"). Users

should also be cognizant of Federal requirements.

d) The word "shall" is used where practice is sufficiently

standardized to warrant compliance with specific requirements, or

where safeguarding the public health or protecting water quality

justifies such definite action. Words such as "should",

"recommended" or "preferred" indicate desirable procedures or

methods with deviations subject to individual project

consideration.

e) Definitions of terms and their use are intended to be in

accordance with the GLOSSARY - WATER AND WASTEWATER CONTROL

ENGINEERING, jointly prepared by the American Public Health

Association (APHA), American Water Works Association (AWWA),

American Society of Civil Engineers (ASCE), and Water Environment

Federation (WEF). The units of expression are in accordance with

the WEF Manual of Practice Number 6, Units of Expression for

Wastewater Treatment.

(Source: Added at 21 Ill. Reg. 12444, effective August 28, 1997)

a) The following materials are incorporated by reference:

1) "Glossary: Water and Wastewater Control Engineering", Joint

Editorial Board of the American Public Health Association,

American Society of Civil Engineers, American Wasteworks

Association, American Pollution Control Federation (1969).

2) ASTM Standards - American Society for Testing and Materials,

100 Bar Harbor Drive, West Conshohoken PA:

ASTM C12-95 -- "Standard Practice for Installing Vitrified

Clay Pipe Lines", Vol. 04.05, Chemical Resistant Materials,

Vitrified Clay, Concrete, Fiber-Cement Products; Mortars;

Masonry (1996).

ASTM C969-94 -- "Standard Practice for Infiltration and

Exfiltration Acceptance Testing of Installed Precast Concrete

Pipe Sewer Lines", Vol. 04.05, Chemical Resistant Materials,

Vitrified Clay, Concrete, Fiber-Cement Products; Mortars;

Masonry (1996).

ASTM C124 -- "Standard Test Method for Concrete Sewer

Manholes by the Negative Pressure (Vacuum) Test", Vol. 04.05,

Chemical Resistant Materials, Vitrified Clay, Concrete,

Fiber-Cement Products; Mortars; Masonry (1996).

ASTM D2321 -- "Standard Practice for Underground Installation

of Themoplastic Pipe for Sewers and Other Gravity-Flow

Applications", Vol. 08.04, Plastic Pipe and Building Products

(1996).

3) "AWWA Standard for Installation of Ductile-Iron Mains and

their Appurtenances", ANSI/AWWA C600-93 (1994) American

Wasteworks Association, 6666 Quincy Avenue, Denver CO 80235.

4) "National Electrical Code Handbook", 7th ed. (1996), National

Fire Protection Association, 1 Batterymarch Park, P.O. Box

9101, Quincy MA 02269-9101.

5) "Standard Specifications for Water and Sewer Main

Construction in Illinois", 5th ed. (1996), Illinois Society

of Professional Engineers, Illinois Municipal League, the

Association General Contractors of Illinois, Underground

Contractors Association.

6) "Standard Specifications for Road and Bridge Construction"

(1997), Illinois Department of Transportation.

7) Manuals of Practice, Joint Task Force of the Water

Environment Federation (WEF) (formerly Water Pollution

Control Federation), 601 Wythe Street, Alexandria VA

22314-1994 and the American Society of Civil Engineers

(ASCE), 345 East 47th Street, New York NY 10017-2398:

"Gravity Sanitary Sewer Design and Construction", WPCF Manual

of Practice (MOP) No. FD-5 (1982).

"Units of Expression for Wastewater Management", WEF Manual

of Practice (MOP) No. 6 (1982).

"Design of Municipal Wastewater Treatment Plants", vol. 1,

WEF Manual of Practice (MOP) No. 8 (1992).

b) The incorporations cited in this Section include no further

editions or amendments.

(Source: Added at 21 Ill. Reg. 12444, effective August 28, 1997)

SUBPART B: ENGINEERING REPORTS, PLANS AND SPECIFICATIONS

The criteria in this Subpart B are intended to be the technical basis for

the preparation of the engineering reports and plans and specifications for

waste collection and treatment works. For project planning requirements,

applicable State and Federal guidance, regulations and statutes shall be

consulted.

a) Grant Projects

For projects that will be funded by Stateor Federal grants,

applicable regulations, policy and guidance documents will govern

the non-technical requirements and shall be used in the facility

planning process.

b) Non Grant Projects

For those projects which are not covered by applicable State or

Federal project planning requirements or for those other projects

in which there is no project planning guidance in the applicable

State or Federal regulations or statutes, the project planning

guidance set forth in Section 370.112 shall be utilized.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) General

1) The engineering report assembles basic information; presents

design criteria and assumptions; examines alternate projects

including preliminary layouts and cost estimates; describes

financing methods, user charges and operation and maintenance

costs; reviews organizational and staffing requirements;

offers a conclusion with a proposed project for client

consideration; and outlines official actions and procedures

to implement the project.

2) The concept, factual data and controlling assumptions and

considerations for the functional planning of sewerage

facilities are presented for each process unit and for the

whole system. These data form the continuing technical basis

for the detailed design and preparation of construction plans

and specifications.

3) Architectural, structural, mechanical and electrical designs

are usually excluded. Sketches may be used to aid in

presentation of a project. Outline specifications of process

units, special equipment, etc., may be included.

4) Engineering reports are not required for sewer extensions or

sewer connections, but shall be required for the following

projects:

A) New treatment plants.

B) Expansion or major modification of existing plants.

C) New collection systems.

D) Major upgrading of existing collection systems.

b) Content

The engineering report shall:

1) Prescribe design period and projected population.

2) Describe the specific service area for immediate

consideration and indicate possible extensions and ultimate

use.

3) Present data and information on anticipated quantities of

flow and wastewater constituents. Data from comparable

existing installations may be used to develop the design

basis of the proposed facilities if data for the project

under design cannot be obtained in accordance with procedures

set forth in Subparts C, D and E of these standards.

4) Specify the scope and nature of collection system including

pump stations and force mains for immediate and ultimate

service areas.

5) Discuss various treatment alternatives with reference to

optimum treatability and other relevant factors.

6) Develop a detailed basis of design for the recommended

treatment process.

7) Indicate compliance with applicable effluent limitations and

discuss the impact of the project on receiving waters.

8) Indicate compliance with the requirements of the Illinois

Groundwater Protection Act [415 ILCS 55].

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

The following flows shall be identified in the basis of design for sewers,

lift stations, sewage treatment plants, treatment units and other

wastewater handling facilities.

a) Design Average Flow

The design average flow is the average of the daily volumes to be

received for a continuous 12-month period of the design year,

expressed as a volume per unit of time.

b) Design Maximum Flow

The design maximum flow is the largest volume of flow to be

received during a continuous 24-hour period, expressed as a volume

per unit of time.

c) Design Peak Hourly Flow

The design peak hourly flow is the largest volume of flow to be

received during a one hour period, expressed as a volume per unit

of time.

d) Design Peak Flow

The design peak flow is the instantaneous maximum flowrate to be

received.

(Source: Added at 21 Ill. Reg. 12444, effective August 28, 1997)

a) General

Detail plans shall contain as necessary, the following:

1) Plan views.

2) Elevations.

3) Sections and supplementary views which, together with the

specifications and general layouts, facilitate construction

of the works.

4) Dimensions and relative elevations of structures.

5) Location and outline form of equipment.

6) Location and sizing of piping.

7) Water levels.

8) Ground elevations.

9) Location and identification of all private and public water

supply wells (refer to Section 370.210(b)(8)), structures and

facilities (refer to Section 370.350(b)(1)(A)).

10) Descriptive notations as necessary for clarity.

b) Plans of Sewers

1) General Plan

Except as provided in subsection (b)(1)(C) below, a

comprehensive plan of the existing and proposed sewers shall

be submitted for projects involving new sewer systems or

substantial additions to existing systems. This plan shall

show the following:

A) Geographical Features

i) Topography and elevations: Existing or proposed

streets and all streams or water surfaces shall be

clearly shown. Contour lines at suitable intervals

should be included.

ii) Streams: The direction of flow in all streams, and

high and low water elevations of all water surfaces

at sewer outlets and overflows shall be shown.

iii) Boundaries: The boundary lines of the

municipality and the sewer district or area to be

sewered shall be shown.

B) Sewers

The plan shall show the location, size and direction of

flow of all existing and proposed sanitary and combined

sewers draining to the treatment works concerned.

C) Sewer Atlas

The comprehensive plan of the existing sewers described

above need not be submitted in each case if the system

owner has furnished the Agency a copy of its sewer atlas

showing the information required by subsection (b)(1).

The project submittal, however, must include all the

proposed work, and must be accompanied by a location map

showing the proposed project and the route of the outlet

sewer to the receiving plant, where necessary.

2) Detail Plans

Detail plans shall be submitted. Profiles should have a

horizontal scale of not more than 100 feet to the inch and a

vertical scale of not more than 10 feet to the inch. Plan

views should be drawn to a corresponding horizontal scale.

Plans and profiles shall show:

A) Location of streets and sewers.

B) Line of ground surface, size, material and type of pipe,

length between manholes, invert and surface elevation at

each manhole, and grade of sewer between each two

adjacent manholes. All manholes shall be numbered on

the plan and correspondingly numbered on the profile.

C) Except where overhead sewers are required by local

ordinance, if there is any question of the sewer being

sufficiently deep to serve any residence, the elevation

and location of the basement floor shall be plotted on

the profile of the sewer which is to serve the house in

question. The engineer shall state that all sewers are

sufficiently deep to serve adjacent basements except

where otherwise noted on the plans.

D) Locations of all special features such as inverted

siphons, concrete encasements, elevated sewers, etc.

E) All known existing structures both above and below

ground which might interfere with the proposed

construction, particularly water mains, gas mains,

storm drains, etc.

F) Special detail drawings, made to a scale to clearly show

the nature of the design, shall be furnished to show the

following particulars:

i) All stream crossings and sewer outlets, with

elevations of the stream bed and of normal and

extreme high and low water levels.

ii) Cross sections and details of all special or non

standard joints.

iii) Details of all sewer appurtenances such as

manholes, lampholes, inspection chambers, inverted

siphons, regulators, tide gates and elevated

sewers.

c) Plans of Sewage Pumping Stations

1) Location Plan

A plan shall be submitted for projects involving construction

or revision of pumping stations. This plan shall show the

following:

A) The location and extent of the tributary area.

B) Any municipal boundaries within the tributary area.

C) The location of the pumping station and force main.

2) Detail Plan

Detail plans shall be submitted showing the following where

applicable:

A) Grading plan of the station site.

B) Location of existing pumping station.

C) Proposed pumping station, including provisions for

installation of future pumps or ejectors.

D) Elevation of high flood water at the site, and maximum

elevation of sewage in the collection system upon

occasion of power failure, and the pumping station

elevations.

E) Test borings and groundwater elevations.

F) Force main routing and profile.

d) Plans of Sewage Treatment Plants

1) Location Plan

A) A plan shall be submitted showing the sewage treatment

plant in relation to the remainder of the system.

B) Sufficient topographic features shall be included to

indicate its location with relation to streams and the

point of discharge of treated effluent.

C) All residences within one-half mile of the site shall be

shown.

2) General Layout

Layouts of the proposed sewage treatment plant shall be

submitted, showing:

A) Topography of the site.

B) Size and location of plant structures.

C) Schematic flow diagram showing the flow through various

plant units.

D) Piping, including any arrangements for by-passing

individual units. Materials handled and direction of

flow through pipes shall be shown.

E) Test borings and expected range of ground water

elevations.

3) Detail Plans

Detail plans shall show the following:

A) Location, dimensions and elevations of all existing and

proposed plant facilities, including flood protection

structures where applicable.

B) Elevations of high and low water levels of the body of

water to which the plant effluent is to be discharged.

C) Type, size, pertinent features, and manufacturer's rated

capacity of all pumps, blowers, motors and other

mechanical devices.

D) Hydraulic profiles of the treatment plant at design peak

flow including recirculated flows at the 25-year flood

elevation in the receiving watercourse. To ensure their

proper functioning, the hydraulic profile at measuring

devices at minimum flow shall be shown.

E) Hydraulic profiles shall be shown for supernatant liquor

lines, recirculating flow piping and sludge transfer

lines at the design peak flows carried by each system.

F) Adequate description of any features not otherwise

covered by specifications or engineer's report.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

<BSection 370.230 Specifications to Accompany Detailed Engineering Plan

Drawings>>

a) Complete technical specifications for the construction of sewers,

sewage pumping stations, sewage treatment plants, and all

appurtenances, shall accompany the plans.

b) The specifications accompanying construction drawings shall

include, but not be limited to, the following:

1) All construction information, not shown on the drawings,

which is necessary to inform the builder in detail of the

design requirements as to the quality of materials and

workmanship and fabrication of the project.

2) The type, size, strength, operating characteristics and

rating of equipment.

3) Allowable infiltration.

4) The complete requirements for all mechanical and electrical

equipment, including machinery, valves, piping and jointing

of pipe.

5) Electrical apparatus, wiring and meters.

6) Laboratory fixtures and equipment.

7) Operating tools.

8) Construction materials.

9) Special filter materials such as stone, sand, gravel or slag.

10) Chemicals when used.

11) Miscellaneous appurtenances.

12) Instruction for testing materials and equipment as necessary.

13) Availability of soil boring information.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Any deviations from approved plans or specifications for

structural configuration, appurtenances or manufactured equipment,

affecting capacity, flow, operation of units or operational

safety, and for substitution of the manufactured equipment

specified and depicted in the plan documents shall be approved in

writing by the Agency before such installation of equipment or

construction changes are made.

b) Plans and specifications requiring Agency approval under

subsection (a) should be submitted well in advance of the ordering

and delivery of equipment or any construction work which will be

affected by such changes, to allow sufficient time for review and

approval. Record drawings of the project as completed shall be

submitted to the Agency.

Specifications shall contain a time schedule describing the plant and

collection system operational modes during construction. Where units

essential to effluent quality are involved, temporary measures, such as wet

hauling, sludge storage lagoons and portable pumping facilities shall be

included in the specifications so as to ensure continuity of operation as

required and approved by the Agency.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

Plans and specifications, prepared by an Illinois Registered Professional

Engineer when required by Section 14 of the Illinois Professional

Engineering Act [225 ILCS 325/14], fully describing the design, nature,

function and interrelationship of each individual component of the facility

or source, shall be submitted, except that the Agency may waive this

requirement for plans and specifications when the application is for a

routine renewal.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

SUBPART C: DESIGN OF SEWERS

a) Type of Sewers

The Agency will approve plans for new sewer systems and extensions

only when designed as the separate sanitary type in which

precipitation runoff and ground water from foundation drains are

excluded. The Agency will not approve the installation of new

combined sewers, except as provided in 35 Ill. Adm. Code 306.302.

b) Design Period

Sewer systems should be designed for the estimated ultimate

tributary population, except in considering parts of the systems

that can be readily increased in capacity. Similarly,

consideration should be given to the maximum anticipated capacity

of institutions, industrial parks, etc.

c) Design Factors

In determining the required capacities of sanitary sewers, the

following factors should be considered:

1) Design peak flow.

2) Additional design peak flow from industrial plants.

3) Ground water infiltration.

4) Topography of area.

5) Location of waste treatment plant.

6) Depth of excavation.

7) Pumping requirements.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Per Capita Flow

1) New Sewers for Undeveloped Areas

New sewer systems to serve currently undeveloped areas shall

be designed on the basis of a design average flow of not

less than 100 gallons per capita per day which is assumed to

cover normal infiltration, but an additional allowance

should be made where conditions are unfavorable.

2) New Sewers for Existing Developed Areas

For new sewers designed to serve existing developed areas,

the design average flow per capita (100 gpd) shall be

appropriately increased to allow for inflow/infiltration

contributions from the existing buildings other than roof and

foundation drains which shall be excluded in accordance with

Section 370.121(a).

b) Design Peak Flow

1) The design peak flow for sanitary sewers shall be selected

based on one of the following methods:

A) The ratio of peak to average daily flow as determined

from Appendix D, Figure No. 1.

B) Values established from an infiltration/inflow study

acceptable to the Agency.

2) Use of other values for the design peak flow will be

considered if justified on the basis of extensive

documentation.

3) Combined Sewer Interceptors

Intercepting sewers, in the case of combined sewer systems,

should fulfill the above requirements for sewers and have

sufficient additional capacity to transport the increment of

combined sewage required by the IPCB Regulations.

c) Alternate Methods

When deviations from subsections (a) and (b) are proposed, a

description of the procedure used for sewer design shall be

included in the submission of plan documents.

d) Basis of Design and Calculations

The basis of design for all sewer projects shall accompany the

plan documents. Calculations shall be submitted to show that

sewers will have sufficient hydraulic capacity to transport the

design peak flows.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Minimum Size

No public gravity sewer conveying raw sewage shall be less than 8

inches in diameter.

b) Depth

Sewers shall be sufficiently deep to prevent freezing. Sewers

should be sufficiently deep to serve basements except where

overhead sewers are required by local ordinances or will be

provided.

1) Minimum Cover

The minimum cover of sewers shall be no less than 3 feet

unless special structural protection is provided.

2) Buoyancy

Where high ground water conditions are anticipated, buoyancy

of sewers shall be considered and, if necessary, adequate

provisions should be made for protection.

c) Slope

1) All sewers shall be designed and constructed to give mean

velocities, when flowing full, of not less than 2.0 feet per

second, based on Manning's formula using an "n" value of

0.013. The following minimum slopes shall be provided;

however, slopes greater than these are desirable:

Minimum Slope in Feet

Sewer Size Per 100 Feet Flow (mgd)

8 inch 0.40 0.49

10 inch 0.28 0.75

12 inch 0.22 1.07

14 inch 0.17 1.43

15 inch 0.15 1.61

16 inch 0.14 1.85

18 inch 0.12 2.35

21 inch 0.10 3.23

24 inch 0.08 4.13

27 inch 0.067 5.17

30 inch 0.058 6.37

33 inch 0.050 7.66

36 inch 0.046 9.23

42 inch 0.036 12.41

2) Under special conditions, if detailed justifiable reasons are

given, slopes slightly less than those required for the 2.0

feet per second velocity when flowing full may be permitted.

Such decreased slopes will only be considered where the depth

of flow will be 0.3 of the diameter or greater for design

average flow. Whenever such decreased slopes are selected,

the design engineer must furnish with his report his

computations of the depths of flow in such pipes at minimum,

design average, and design peak rates of flow. It must be

recognized that decreased slopes may cause additional sewer

maintenance expense and special linings or materials should

be considered for corrosion protection.

3) Uniform Slope

Sewers shall be laid with uniform slope between manholes.

4) Steep Slope Protection

Sewers on 20 percent slope or greater shall be anchored

securely with concrete anchors or equal, spaced as follows:

A) Not over 36 feet center to center on grades 20 percent

and up to 35 percent.

B) Not over 24 feet center to center on grades 35 percent

and up to 50 percent.

C) Not over 16 feet center to center on grades 50 percent

and over.

d) Alignments

1) Straight Alignments

Except as noted in subsection (d)(2), all sewers shall be

laid with straight alignments between manholes.

2) Curvilinear Alignments

Curvilinear sewers are permitted in special cases provided

the following minimum requirements are met:

A) Curvilinear Sewers 24 Inches in Diameter and Smaller

i) Location: Curvilinear alignments should follow the

general alignment of streets.

ii) Type Curve: Only simple curve design is

acceptable.

iii) Radius of Curvature: The minimum allowable radius

of curvature is 300 feet.

iv) Manholes: Manholes are required at the beginning

and end of all curves.

v) Joints: Compression joints are required. The ASTM

or AWWA maximum allowable deflection of the pipe

joints shall not be exceeded.

vi) Velocity: In order to maintain a minimum velocity

of 2 feet per second in curvilinear sewers,

hydraulics of the curvilinear alignment shall be

taken into account and the minimum slopes indicated

in subsection (c)(1) must be increased accordingly.

B) Curvilinear Sewers 24 Inches Through 48 Inches in

Diameter

Curvilinear sewers larger than 24 inches in diameter up

to 48 inches in diameter constructed with pressure pipe

meeting AWWA standards may be used. Other curvilinear

sewers larger than 24 inches in diameter up to 48 inches

in diameter shall meet the requirements of subsection

(d)(2)(A) except that the joints must be manufactured so

that they fit together squarely without deflection at

the design curvature and the radius of curvature may be

less than 300 feet.

C) Curvilinear Sewers Larger Than 48 Inches in Diameter

Curvilinear sewers larger than 48 inches in diameter

shall be provided with square fitting compression joints

and shall meet the requirements of subsection

(d)(2)(A)(vi). The remaining design requirements under

subsection (d)(2)(A) for these sewers will be reviewed

by the Agency on a case by case basis.

e) Increasing Size

When a smaller sewer joins a larger one, the invert of the larger

sewer should be sufficiently lower to maintain the energy

gradient. An approximate method for securing these results is to

place the 0.8 depth point of both sewers at the same elevation.

f) High Velocity Protection

Where velocities greater than 15 feet per second are attained, the

special provisions described in subsection (c)(4) shall be made to

protect against displacement by erosion and shock.

g) Materials and Installation

1) Materials

A) Any generally accepted material for sewers will be given

consideration, but the material selected should be

suitable for local conditions, such as character of

industrial wastes, possibility of septicity, soil

characteristics, exceptionally heavy external loadings,

abrasion, structural considerations and similar

problems.

B) All sewers shall be designed and installed to prevent

damage from superimposed loads. Proper allowance for

loads on the sewer shall be made because of the width

and depth of trench. When the bearing strength of the

pipe is not adequate to withstand the superimposed

loading, other pipe material, special handling, concrete

cradle or special construction shall be used.

C) For new pipe materials for which ASTM standards have not

been established (see subsection (g)(2)), the designing

engineer shall provide complete installation

specifications developed on the basis of criteria

adequately documented and certified in writing by the

pipe manufacturer to be satisfactory for the design

conditions for the specific project. Such documentation

and manufacturers' certification shall be submitted as a

part of the project plan documents.

2) Installation

A) Standards

i) Installation specifications shall contain

appropriate requirements based on the criteria,

standards and requirements established by ASTM.

Requirements shall be set forth in the

specifications for the pipe and methods of bedding

and backfilling thereof so as not to damage the

pipe or its joints, impede cleaning operations and

future tapping, nor create excessive side fill

pressures or ovalation of the pipe, nor seriously

impair flow capacity.

ii) For new pipe material, the installation

specifications shall meet the provisions of

subsection (g)(1).

B) Trenching

i) The width of the trench shall be ample to allow the

pipe to be laid and jointed properly and to allow

the backfill to be placed and compacted as needed.

The trench sides shall be kept as nearly vertical

as possible. When wider trenches are dug,

appropriate bedding class and pipe strength shall

be used.

ii) Ledge rock, boulders, and large stones shall be

removed to provide a minimum clearance of 4 inches

below and on each side of all pipe and joints.

C) Bedding

i) Bedding classes A, B, or C, as described in ASTM

Cl2-95, "Standard Practice for Installing Vitrified

Clay Pipe Lines" (1996) or "Standard Specifications

for Water and Sewer Main Construction in Illinois",

5th ed. (1996) (no later additions or amendments)

or WPCF Manual of Practice (MOP) No. FD-5 (1982)

(no later additions or amendments) shall be used

for all rigid pipe provided the proper strength

pipe is used with the specified bedding to support

the anticipated load.

ii) Bedding class I, II, or III, as described in ASTM

D2321-89, "Standard Practice for Underground

Installation of Thermoplastic Pipe for Sewers and

Other Gravity-Flow Applications" (1996) (no later

editions or amendments) or Standard Specifications

for Water and Sewer Main Construction in Illinois,

5th ed. (1996) (no later additions or amendments),

or WPCF MOP No. FD-5 (1982)(no later additions or

amendments) shall be used for all flexible pipe

provided the proper strength pipe is used with the

specified bedding to support the anticipated load.

D) Backfill

i) Backfill shall be of a suitable material removed

from excavation except where other material is

specified. Debris, frozen material, large clods or

stones, organic matter, or other unstable materials

shall not be used for backfill within 2 feet of the

top of the pipe.

ii) Backfill shall be placed in such a manner as not to

disturb the alignment of the pipe.

iii) For flexible pipe, as a minimum, backfill material

shall be placed and carefully compacted in

accordance with ASTM D2321-89 (1996) to provide the

necessary support for the pipe.

3) Deflection Testing of Flexible Pipe.

A) The design specifications shall provide that the first

1200 feet of sewer and at least 10% of the remainder of

the sewer project shall be deflection tested. The

entire length of a sewer of less than 1200 feet shall be

deflection tested.

B) If the deflection test is to be run using a rigid ball

or mandrel, it shall have a diameter equal to 95% of the

inside or base diameter of the pipe as established in

the ASTM standard to which the pipe is manufactured.

The test shall be performed without mechanical pulling

devices.

C) The individual lines to be tested shall be tested for

final acceptance no sooner than 30 days after they have

been installed.

D) Whenever possible and practical, the testing shall

initiate at the downstream lines and proceed towards the

upstream lines.

E) No pipe shall exceed a deflection of 5%.

F) In the event that the deflection exceeds the 5% limit in

10% or more of the manhole intervals tested, the total

sewer project shall be tested.

h) Joints and Infiltration

1) Joints

The type and method of making joints and the materials used

shall be included in the specifications and also shall be

shown on the plans. Sewer joints shall be specified to

minimize infiltration and to prevent the entrance of roots.

Joint material shall conform to ASTM standards. Cement grout

joints shall not be used for pipe to pipe joints.

2) Leakage Testing

Leakage tests shall be specified.

A) Test Sections

The design specifications shall provide that the first

1200 feet and at least 10% of the remainder of the sewer

project shall be tested for leakage. The entire length

of a sewer of less than 1200 feet shall be tested for

leakage. In the event that 10% or more of the manhole

intervals tested do not pass the leakage test, the

entire sewer project shall be tested.

B) Testing Methods

Testing methods may include appropriate water or low

pressure air testing. The use of television cameras or

other visual methods for inspection prior to placing the

sewer in service and prior to acceptance is

recommended.

C) Water Testing

i) The leakage outward or inward (exfiltration or

infiltration) shall not exceed the following limits

in gallons per inch of pipe diameter per mile per

day for any section of the system:

Exfiltration: 240

Infiltration: 200

ii) An exfiltration or infiltration test shall be

performed with a minimum positive head of 2 feet.

D) Air Testing

If used, the air test shall, as a minimum, conform to

the test procedure described in Section 31-1.11B of

Standard Specifications for Water and Sewer Main

Construction in Illinois, 5th ed. (1996)(no later

additions or amendments). The specifications shall

require that the time required for a pressure drop from

3.5 to 2.5 PSIG not be less than the time specified in

the Air Test Table in Appendix C. The testing methods

selected should take into consideration the range in

groundwater elevations projected and the situation

during the test.

i) Service Connections

Sewer service connections shall meet the same criteria as public

sanitary sewers described elsewhere in this Subpart C except as

noted in this subsection (i). Roof and foundation drain

connections to the sewer service connection are prohibited except

as provided for in 35 Ill. Adm. Code 306.302. The service

connection tap into the public sewer shall be watertight and shall

not protrude into the public sewer. If a saddle type connection

is used, it shall be a commercially available device designed to

join with the types of pipe that are to be connected. All

materials used to make service connections shall be compatible

with one another and with the pipe materials to be joined, and

shall be corrosion-proof.

1) Size

Service sewers and fittings shall be a minimum of 4 inches in

diameter, but shall not be less than the diameter of the

plumbing pipe from the building.

2) Slope

Service sewers shall have a minimum slope of 1%.

3) Alignment

When straight line alignment is not maintained on service

connections, cleanouts or manholes shall be provided at

points of changes in alignment.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Location

Except as noted in Section 370.123(d)(2), manholes shall be

installed at the end of each line; at all changes in grade, size

or alignment; at all sewer intersections; and at distances not

greater than 400 feet for sewers 15 inches or less, and 500 feet

for sewers 18 inches through 30 inches. Distances up to 600 feet

may be approved in cases where adequate modern cleaning equipment

for such spacing is provided. Greater spacing may be permitted in

larger sewers and in those carrying a settled effluent. Lampholes

may be used only for special conditions and shall not be

substituted for manholes nor installed at the end of laterals

greater than 150 feet in length.

b) Type

1) Drop Type

A pipe shall be provided for a sewer entering a manhole where

its invert elevation is more than 24 inches above the manhole

invert. If an inside drop pipe is used, the manhole diameter

shall be large enough to provide a minimum clearance of 48

inches between the pipe and the opposite side of the manhole.

Inside drip pipes shall be anchored to the manhole wall with

corrosion-proof fasteners and bands. For sewers 36 inches in

diameter or greater, the requirements for a drop pipe do not

apply if the spring line of the incoming pipe is at or below

the spring line of the main sewer. As a minimum, the

diameter of the drop pipe shall be at least 2/3 as large as

the diameter of the sewer tributary to the drop pipe.

2) Non Drop Type

Where the difference in elevation between the incoming sewer

invert and the manhole invert is less than 24 inches, the

manhole invert should be filleted to prevent solids

deposition.

c) Diameter

1) For sewers 36 inches in diameter and smaller, the minimum

diameter of manholes shall be 48 inches. For sewers larger

than 36 inches in diameter, the manhole diameter at the

invert shall be sufficiently large to accommodate the

incoming pipes; and the riser barrel diameter shall be a

minimum of 48 inches.

2) A minimum access lid diameter of 24 inches shall be provided.

d) Flow Channel

The flow channel through manholes should be made to conform in

shape and slope to that of the sewers. A bench shall be provided

which should have a minimum slope of 2 inches per foot.

e) Watertightness

1) Construction Requirements

Watertight manhole covers shall be used wherever the manhole

tops may be flooded by surface runoff or high water or are

below cover. Pickholes shall not be larger than 1 inch in

diameter or shall be of the concealed type. Construction

lifting holes on manhole rings shall be plugged from the

outside and the exterior and joints of the manhole elements

shall be waterproofed. Precast inlet and outlet connections

fitted with "0" rings or other equally watertight connections

shall be provided.

2) Inspection

The specifications shall include a requirement for inspection

and leakage testing of all manholes for watertightness in

accordance with ASTM C969-94--"Standard Practice for

Infiltration and Exfiltration Acceptance Testing of Installed

Precast Concrete Pipe Sewer Lines", Vol. 04.05, Chemical

Resistant Materials, Vitrified Clay, Concrete, Fiber-Cement

Products; Mortars; Masonry (1996) (no later editions or

amendments) or ASTM C1244-93 "Standard Test Method for

Concrete Sewer Manholes by the Negative Pressure (Vacuum)

Test", Vol. 04.05, Chemical Resistant Materials, Vitrified

Clay, Concrete, Fiber-Cement Products; Mortars; Masonry

(1996) (no later editions or amendments) prior to placing

into service.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Location of Sewers on Streams

1) Cover Depth

A) The top of all sewers entering or crossing streams shall

be at a sufficient depth below the natural bottom of the

stream bed to protect the sewer line. In general the

following cover requirements must be met:

i) One foot of cover is required where the sewer is

located in rock.

ii) Three feet of cover is required in other material.

In major streams, more than three feet of cover may

be required.

iii) In paved stream channels, the top of the sewer

line should be placed below the bottom of the

channel pavement.

B) Less cover will be approved only if the proposed sewer

crossing will not interfere with the future improvements

to the stream channel. Reasons for requesting less

cover should be given in the project proposal.

2) Horizontal Location

Sewers located along streams shall be located outside of the

stream bed and sufficiently removed therefrom to provide for

future possible stream widening and to prevent pollution by

siltation during construction.

3) Structures

The sewer outfalls, headwalls, manholes, gate boxes, or other

structures shall be located so they do not interfere with the

free discharge of flood flows of the stream.

4) Alignment

Sewers crossing streams should be designed to cross the

stream as nearly perpendicular to the stream flow as possible

and shall be designed without change in grade. Sewer

systems shall be designed to minimize the number of stream

crossings.

b) Construction

1) Materials and Backfill

A) Sewers entering or crossing streams shall be constructed

of cast or ductile iron pipe with mechanical joints and

shall be capable of absorbing pipe movement and

joint-deflection while remaining intact and watertight.

B) The backfill used in the trench shall be coarse

aggregate, gravel, or other materials which will not

cause siltation, pipe damage during placement or

chemical corrosion in place.

2) Siltation and Erosion

Construction methods that will minimize siltation and erosion

shall be employed. The design engineer shall include in the

project specifications the methods to be employed in the

construction of sewers in or near streams to provide

adequate control of siltation and erosion. Specifications

shall require that cleanup, grading, seeding, and planting

or restoration of all work areas shall begin immediately.

Exposed areas shall not remain unprotected for more than

seven days.

c) Aerial Crossings

1) Structural Support

Support shall be provided for all joints in pipes utilized

for aerial crossings. The supports shall be designed to

prevent frost heave, overturning and settlement.

2) Freeze and Expansion Protection

Protection against freezing shall be provided. This may be

accomplished through the use of insulation and increased

slope. Expansion jointing shall be provided between the

aerial and buried sections of the sewer line.

3) Flood Clearance

For aerial stream crossings, the impact of flood waters and

debris shall be considered. The bottom of the pipe should be

placed no lower than the elevation of the 50 year flood.

d) Inverted Siphons

Inverted siphons shall have not less than 2 barrels, with a

minimum pipe size of 6 inches and shall be provided with necessary

appurtenances for convenient flushing and maintenance. Long radius

fittings should be used. The inlet and outlet structures shall

have adequate clearances for rodding; and in general, sufficient

head shall be provided and pipe sizes selected to secure

velocities of at least 3.0 feet per second for design average

flows. The inlet and outlet structures shall be designed so that

the design average flow is diverted to 1 barrel, and so that

either barrel may be cut out of service for cleaning.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Water Supply Interconnections

There shall be no physical connections between a public or private

potable water supply system and a sewer, or appurtenance thereto,

which would permit the passage of any sewage or polluted water

into the potable supply.

b) Location Relative to Water Works Structures

1) Location and Soil Condition

A) The engineering plan documents shall show the location

of all existing water works structures (basins, wells,

other treatment units, etc.) that are within 200 feet of

the proposed sewer.

B) Soil conditions in the vicinity of the water works

structures shall be investigated and depicted on the

plans.

2) Minimum Distances

The following minimum distances apply to clay and loan soils

and, as a minimum, shall be doubled for sand. In areas

where creviced limestone or gravel may be encountered, the

Agency shall be contacted for a determination as to what

minimum separation distances and special construction will be

required.

A) Non-watertight sewers and sewer appurtenances such as

manholes and wetwells shall not be located closer than

50 feet from water works structures.

B) Sewers located closer than 50 feet to water works

structures shall be constructed with water main quality

pipe and joints that comply with 35 Ill. Adm. Code

653.119. All such pipe shall be pressure tested in

accordance with "AWWA Standard for Installation of

Ductile-Iron Water Mains and their Appurtenances,"

ANSI/AWWA C600-93 (1994), (no later editions or

amendments) for a working pressure equal to or greater

than the maximum possible surcharge head to assure

watertightness prior to backfilling. No sewer shall be

located closer than 10 feet from water works structures.

c) Relation to Water Mains

1) Horizontal and Vertical Separation

A) Whenever possible, a sewer must be at least ten feet

horizontally from any existing or proposed water main.

B) Should local conditions exist which would prevent a

lateral separation of ten feet, a sewer may be closer

than ten feet to a water main provided that the water

main invert is at least eighteen inches above the crown

of the sewer, and is either in a separate trench or in

the same trench on an undisturbed earth shelf located to

one side of the sewer.

C) If it is impossible to obtain proper horizontal and

vertical separation as described above, both the water

main and sewer must be constructed with water main

quality pipe and joints that comply with 35 Ill. Adm.

Code 653.119 and shall be pressure tested in accordance

with "AWWA Standard for Installation of Ductile-Iron

Water Mains and their Appurtenances," ANSI/AWWA C600-93

(1994) (no later editions or amendments) for a working

pressure equal to or greater than the maximum possible

surcharge head to assure watertightness before

backfilling.

2) Water-Sewer Line Crossings

A) Whenever possible, sewers crossing water mains shall be

laid with the sewer below the water main with the crown

of the sewer a minimum of 18 inches below the invert of

the water main. The vertical separation shall be

maintained on each side of the crossing until the

perpendicular distance from the water main to the sewer

is at least 10 feet. The crossing shall be arranged so

that the sewer joints will be equidistant and as far as

possible from the water main joints. Adequate support

shall be provided for the water mains to prevent damage

due to settling of the sewer trench. Refer to Appendix

H, Drawing No. 1.

B) Where a sewer crosses under a water main and it is not

possible to provide an 18-inch vertical separation, the

following special construction methods shall be

specified (refer to Appendix H, Drawing No. 2):

i) The sewer shall either be constructed with water

main pipe and joints that comply with 35 Ill. Adm.

Code 653.119 and shall be pressure tested in

accordance with "AWWA Standard for Installation of

Ductile-Iron Water Mains and their Appurtenances,"

ANSI/AWWA C600-93 (1994) (no later editions or

amendments) for a working pressure equal to or

greater than the maximum possible surcharge head

or shall be encased in a carrier pipe with the ends

sealed, that, along with the joints, complies with

35 Ill. Adm. Code 653.119.

ii) The water main quality sewer or carrier pipe shall

extend on each side of the crossing to a point

where the perpendicular distance from the water

main to the sewer is at least 10 feet.

iii) For the required length of the water main quality

sewer or carrier pipe, omit the select granular

cradle and granular backfill to one foot over the

crown of the sewer and use selected excavated

material (Class IV) and compact to 95% of Standard

Proctor maximum density.

iv) Point loads between the sewer or sewer casing and

the water main are prohibited.

v) Adequate support shall be provided for the water

main to prevent damage due to settling of the sewer

trench.

C) Where it is not possible for a proposed sewer to cross

under an existing water main, the specifications shall

require the construction methods set out in subsection

(c)(2)(B) above and shall require that any select

granular backfill above the crown of the water main be

removed within the width of the proposed sewer trench

and be replaced with select excavated material (Class

IV) compacted to 95% of Standard Proctor maximum

density. Where a proposed sewer must cross over a

proposed water main, an 18-inch vertical separation

shall be maintained. Refer to Appendix H, Drawing No.

3) Sewer Manhole Separation From Water Main

No water pipe shall pass through or come into contact with

any part of a sewer manhole.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

SUBPART D: SEWAGE PUMPING STATIONS

a) Flooding

Sewage pumping station structures and electrical and mechanical

equipment shall be protected from physical damage by the 100 year

flood. Sewage pumping stations should remain fully operational

and accessible during the 25 year flood. Regulations of State

and Federal agencies regarding flood plain obstructions shall be

considered.

b) Accessibility

The pumping station shall be readily accessible by maintenance

vehicles during all weather conditions. The facility should be

located off the traffic way of streets and alleys.

c) Grit

Where it is necessary to pump sewage prior to grit removal, the

design of the wet well and pump station piping shall receive

special consideration to avoid operational problems from the

accumulation of grit.

The following items should be given consideration in the design of sewage

pumping stations:

a) Type

Sewage pumping stations in general use fall into three types:

wet well/dry well, submersible, and suction lift.

b) Structures

1) Separation

Dry wells, including their superstructure, shall be

completely separated from the wet well. Common walls must be

gastight.

2) Pump Removal

Provision shall be made to facilitate removing pumps and

motors.

3) Access

A) Suitable and safe means of access shall be provided to

dry wells and to wet wells. Access to wet wells

containing either bar screens or mechanical equipment

requiring inspection or maintenance shall conform to

Section 370.600(a)(2)(C).

B) For built-in-place pump stations, a stairway to the dry

well with rest landings shall be provided at vertical

intervals not to exceed 12 feet. For factory-built pump

stations over 15 feet deep, a rigidly fixed landing

shall be provided at vertical intervals not to exceed 10

feet. Where a landing is used, a suitable and rigidly

fixed barrier shall be provided to prevent an individual

from falling past the intermediate landing to a lower

level. A manlift or elevator may be used in lieu of

landings in a factory-built station, provided emergency

access is included in the design.

4) Buoyancy

Where high ground water conditions are anticipated, buoyancy

of the sewage pumping station structures shall be considered

and, if necessary, adequate provisions shall be made for

protection.

c) Pumps and Pneumatic Ejectors

1) Multiple Units

Multiple pumps or ejector units shall be provided. Where

only two units are provided, they shall be of the same size.

Units shall have capacity such that, with any unit out of

service, the remaining units will have capacity to handle the

design peak flows. A single pump equipped with an

audio-visual alarm system to warn of failure may be used when

serving only one single-family dwelling.

2) Protection Against Clogging

A) Pumps handling combined sewage shall be preceded by

readily accessible bar racks to protect the pumps from

clogging or damage. Bar racks should have clear

openings not exceeding 1 inch. Where a bar rack is

provided, a mechanical hoist shall also be provided.

Where the size of the installation warrants,

mechanically cleaned and/or duplicate bar racks shall be

provided.

B) Pumps handling separate sanitary sewage from 30 inch or

larger diameter sewers shall be protected by bar racks

meeting the above requirements. Appropriate protection

from clogging shall also be considered for small pumping

stations.

3) Pump Openings

Pumps handling raw sewage shall be capable of passing spheres

of at least 3 inches in diameter. Pump suction and discharge

openings shall be at least 4 inches in diameter. Grinder

pumps that do not meet these requirements may be used solely

for lift stations with a capacity of 70 gpm or less with the

largest unit out of service.

4) Priming

The pump shall be so placed that under normal operating

conditions it will operate under a positive suction head,

except as specified in Section 370.133.

5) Electrical Equipment

Electrical systems and components (e.g., motors, lights,

cables, conduits, switchboxes, control circuits, etc.) in raw

sewage wet wells, or in enclosed or partially enclosed spaces

where hazardous concentrations of flammable gases or vapors

may be present, shall comply with the National Electrical

Code requirements for Class 1 Group D, Division 1 locations.

In addition, equipment located in the wet well shall be

suitable for use under corrosive conditions. Each flexible

cable shall be provided with water-tight seal and separate

strain relief. A fused disconnect switch located above

ground shall be provided for all pumping stations. When such

equipment is exposed to weather, it shall meet the

requirements of weatherproof equipment (National Electric

Manufacturers Association (NEMA) 3R or 4).

6) Intake

Each pump shall have an individual intake. Wet well and

intake design should be such as to avoid turbulence near the

intake and to prevent vortex formation.

7) Dry Well Dewatering

Duplicate sump pumps equipped with dual check valves for each

pump shall be provided in the dry well to remove leakage or

drainage with discharge above the maximum high water level of

the wet well. Water ejectors connected to a potable water

supply will not be approved. All floor and walkway surfaces

should have an adequate slope to a point of drainage. Pump

seal leakage shall be piped or channeled directly to the

sump. The sump pumps shall be sized to remove the maximum

pump seal water discharge which would occur in the event of

a pump seal failure.

8) Pumping Rates

The pumps and controls of main pumping stations, and

especially pumping stations operated as part of treatment

works, should be selected to operate at varying delivery

rates. The stations shall be designed to deliver as uniform

flow as practicable in order to minimize hydraulic surges.

The peak design flow of the station shall be determined in

accordance with Sections 370.300(c), 370.310(b) and

370.520(c) and should be adequate to maintain a minimum

velocity of 2 feet per second in the force main. Refer to

Section 370.470(f).

d) Controls

Control float tubes and bubbler lines should be so located as not

to be unduly affected by turbulent flows entering the well or by

the turbulent suction of the pumps. Provision shall be made to

automatically alternate the pumps in use.

e) Valves

Shutoff valves shall be placed on suction and discharge lines of

each pump. A check valve shall be placed on each discharge line,

between the shutoff valve and the pump. Check valves shall not be

located on a vertical rise unless they are specifically designed

for such usage.

f) Wet Wells

1) Divided Wells

Where continuity of pumping station operation is critical,

consideration should be given to dividing the wet well into

two sections, properly interconnected, to facilitate repairs

and cleaning.

2) Size

The design fill time and minimum pump cycle time shall be

taken into account in sizing the wet well. The effective

volume of the wet well shall be based on design average flow

and a filling time not to exceed 30 minutes unless the

facility is designed to provide flow equalization. The pump

manufacturer's duty cycle recommendations shall be used in

selecting the minimum cycle time. When the anticipated

initial flow tributary to the pumping station is less than

the ultimate average design flow, provisions should be made

so that the holding time indicated is not exceeded for

initial flows. When the wet well is designed for flow

equalization as part of a treatment plant, provisions should

be made to prevent septicity.

3) Floor Slope

The wet well floor shall have a minimum slope of 1 to 1 to

the hopper bottom. The horizontal area of the hopper bottom

shall be no greater than necessary for proper installation

and function of the inlet.

4) Air Displacement

Covered wet walls shall provide for air displacement open to

the atmosphere, such as by an inverted "j" tube or similar

means.

g) Ventilation

1) General

Adequate ventilation shall be provided for all pump stations.

Where the dry well is below the ground surface, mechanical

ventilation is required. If screens or mechanical equipment

requiring maintenance or inspection is located in the wet

well, permanently installed ventiliation is required. There

shall be no interconnection between the wet well and dry well

ventilation systems.

2) Air Inlets and Outlets

In dry wells over 15 feet deep, multiple inlets and outlets

should be used. Dampers should not be used on exhaust or

fresh air ducts and fine screens or other obstructions in air

ducts should be avoided to prevent clogging.

3) Electrical Controls

Switches for operation of ventilation equipment should be

marked and located conveniently. All intermittently operated

ventilation equipment shall be interconnected with the

respective pit lighting system. Consideration should be

given also to automatic controls where intermittent operation

is used. The manual lighting ventilation switch shall

override the automatic controls.

4) Fans, Heating and Dehumidification

The fan wheel shall be fabricated from non-sparking material.

Automatic heating and dehumidification equipment shall be

provided in all dry wells. The electrical equipment and

components shall meet the requirements of subsection (c)(5)

above.

5) Wet Wells

Wet well ventilation may be either continuous or

intermittent. Ventilation, if continuous, should provide at

least 12 complete air changes per hour; if intermittent, at

least 30 complete air changes per hour. Air shall be forced

into the wet well by mechanical means rather than exhausted

from the wet well. Portable ventilation equipment shall be

provided for use at submersible pump stations and at wet

wells with no permanently installed ventilation equipment.

6) Dry Wells

Dry well ventilation may be either continuous or

intermittent. Ventilation, if continuous, should provide at

least 6 complete air changes per hour; if intermittent, at

least 30 complete air changes per hour. A system of

two-speed ventilation with an initial ventilation rate of 30

changes per hour for 10 minutes and an automatic switch-over

to 6 changes per hour may be used to conserve heat.

h) Flow Measurement

Suitable devices for measuring sewage flow shall be provided at

all pumping stations. Indicating, totalizing and recording flow

measurement shall be provided at pumping stations with a 1200 gpm

or greater design peak flow. Elapsed time meters used in

conjunction with pumping rate tests may be used for pump stations

with a design peak flow of up to 1200 gpm.

i) Water Supply

There shall be no physical connection between any potable water

supply and a sewage pumping station which under any conditions

might cause contamination of the potable water supply. If a

potable water supply is brought to the station, it should comply

with conditions stipulated under Section 370.146(b)(3). In-line

backflow preventors shall not be used.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Pump Priming and Lift Requirements

Suction lift pumps shall be of the self-priming or vacuum-priming

type and shall meet the applicable requirements of Section

370.132. Suction lift pump stations using dynamic suction lifts

exceeding the limits outlined in the following sections may be

approved upon submission of factory certification of pump

performance and detail calculations indicating satisfactory

performance under the proposed operating conditions. Such

detailed calculations must include static suction lift as

measured from "lead pump off" elevation to center line of pump

suction, friction and other hydraulic losses of the suction

piping, vapor pressure of the liquid, altitude correction,

required net positive suction head, and a safety factor of at

least 6 feet.

1) Self-priming Pumps

Self-priming pumps shall be capable of rapid priming and

repriming at the "lead pump on" elevation. Such self-priming

and repriming shall be accomplished automatically under

design operating conditions. Suction piping should not

exceed the size of the pump suction and shall not exceed 25

feet in total length. Priming lift at the "lead pump on"

elevation shall include a safety factor of at least 4 feet

from the maximum allowable priming lift for the specific

equipment at design operating conditions. The combined total

of dynamic suction lift at the "pump off" elevation and

required net positive suction head at design operating

conditions shall not exceed 22 feet.

2) Vacuum-priming Pumps.

Vacuum-priming pump stations shall be equipped with dual

vacuum pumps capable of automatically and completely removing

air from the suction lift pump. The vacuum pumps shall be

adequately protected from damage due to sewage. The combined

total of dynamic suction lift at the "pump off" elevation and

required net positive suction head at design operating

conditions shall not exceed 22 feet.

b) Equipment, Wet Well Access and Valve Location

The pump equipment compartment shall be above grade or offset and

shall be effectively isolated from the wet well to prevent the

humid and corrosive sewer atmosphere from entering the equipment

compartment. Wet well access shall not be through the equipment

compartment. Wet well access may not be through the equipment

compartment and shall be at least 24 inches in diameter. Gasketed

replacements shall be provided to cover the opening to the wet

well for pump units removed for servicing. Valves shall not be

located in the wet well.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

Submersible pump stations shall meet the applicable requirements under

Section 370.132, except as modified in this Section.

a) Construction

Submersible pumps and motors shall be designed specifically for

raw sewage use, including totally submerged operation during a

portion of each pumping cycle, and shall meet the requirements of

the National Electrical Code (1996). An effective method to

detect shaft seal failure or potential seal failure shall be

provided.

b) Pump Removal

Submersible pumps shall be readily removable and replaceable

without dewatering the wet well or disconnecting any piping in the

wet well.

c) Electrical

1) Power Supply and Control

Electrical supply, control and alarm circuits shall be

designed to provide strain relief and to allow disconnection

from outside the wet well. Terminals and connectors shall be

protected from corrosion by location outside the wet well or

through use of watertight seals. If located outside,

weatherproof equipment shall be used.

2) Controls

The motor control center shall be located outside the wet

well, readily accessible, and be protected by conduit seal or

other appropriate measures meeting the requirements of the

National Electrical Code, to prevent the atmosphere of the

wet well from gaining access to the control center. The

seal shall be so located that the motor may be removed and

electrically disconnected without disturbing the seal.

3) Power Cord

Pump motor power cords shall be designed for flexibility and

serviceability under conditions of extra hard usage and shall

meet the requirements of the National Electric Code (1996)

for flexible cords in sewage pump stations. Ground fault

interruption protection shall be used to de-energize the

circuit in the event of any failure in the electrical

integrity of the cable. Power cord terminal fittings shall

be corrosion-resistant and constructed in a manner to prevent

the entry of moisture into the cable, shall be provided with

strain relief appurtenances, and shall be designed to

facilitate field connecting.

d) Valves

Valves required under Section 370.132(e) shall be located in a

separate valve pit. Provision shall be made to remove accumulated

water from the valve pit. Accumulated water in valve pits deeper

than 4 feet shall be pumped to the wet well or gravity drained to

the ground surface. Valve pits 4 feet deep or less may be gravity

drained to the wet well through a trapped and vented drain that

meets the applicable requirements found in 77 Ill. Adm. Code 890,

"Illinois Plumbing Code". Such pits shall have entrances that

fully expose the pit to the atmosphere. Check valves that are

integral to the pump need not be located in a separate valve pit

provided that the valve can be removed from the wet well in

accordance with subsection (b) above. Provision shall be made for

the use of portable ventiliation equipment during periods of

maintenance.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

Alarm systems shall be provided for pumping stations. The alarm shall be

activated in cases of power failure, pump failure, unauthorized entry, or

any cause of pump station malfunction. Pumping station alarms shall be

telemetered to a municipal facility that is manned 24 hours a day. If such

a facility is not available and a 24-hour holding capacity is not provided,

the alarm shall be telemetered to city offices during normal working hours

and to the home of the person(s) in responsible charge of the lift station

during off-duty hours. Audio-visual alarm systems with a self-contained

power supply may be acceptable in some cases in lieu of the telemetering

system outlined above, depending upon location, station holding capacity

and inspection frequency.

a) Objective

The objective of emergency operation is to prevent the discharge

of raw or partially treated sewage to any waters and to protect

public health by preventing back-up of sewage and subsequent

discharge to basements, streets, and other public and private

property.

b) Emergency Pumping Capability

Provision of emergency pumping capability is mandatory and may be

accomplished by connection of the station to at least two

independent utility substations, or by provision of portable or

in-place internal combustion engine equipment which will generate

electrical or mechanical energy, or by the provision of portable

pumping equipment. Emergency standby systems shall have

sufficient capacity to start up and maintain the total rated

running capacity of the station. Regardless of the type of

emergency standby system provided, a riser from the force main

with rapid connection capabilities and appropriate valving shall

be provided for all lift stations to hook up portable pumps.

c) Emergency High Level Overflows

For use during possible periods of extensive power outages,

mandatory power reductions, or uncontrollable emergency

conditions, consideration should be given to providing a

controlled, high-level wet well overflow to supplement alarm

systems and emergency power generation in order to prevent backup

of sewage into basements, or other discharges which may cause

severe adverse impacts on public interests, including public

health and property damage. Where a high level overflow is

utilized, consideration shall also be given to the installation

of storage/detention tanks, or basins, which shall be made to

drain to the station wet well. Where such overflows affect

public water supplies or waters used for culinary or food

processing purposes, a storage detention basin, or tank, shall be

provided having 2-hour detention capacity at the anticipated

overflow rate.

d) Equipment Requirements

1) General

The following general requirements shall apply to all

internal combustion engines used to drive auxiliary pumps,

service pumps through special drives, or electrical

generating equipment:

A) Engine Protection

The engine must be protected from operating conditions

that would result in damage to equipment. Unless

continuous manual supervision is planned, protective

equipment shall be capable of shutting down the engine

and activating an alarm on site and as provided in

Section 370.135. Protective equipment shall monitor for

conditions of low oil pressure and overheating, except

that oil pressure monitoring will not be required for

engines with splash lubrication.

B) Size

The engine shall have adequate rated power to start and

continuously operate all connected loads.

C) Fuel Type

Reliability and ease of starting, especially during cold

weather conditions, should be considered in the

selection of the type of fuel.

D) Engine Ventilation

The engine shall be located above grade with adequate

ventilation of fuel vapors and exhaust gases.

E) Routine Start-up

All emergency equipment shall be provided with

instructions indicating the need for regular starting

and running of such units at full loads.

F) Protection of Equipment

Emergency equipment shall be protected from damage at

the restoration of regular electrical power.

2) Engine - Drive Pumping Equipment

Where permanently-installed or portable engine-driven pumps

are used, the following requirements in addition to general

requirements shall apply:

A) Pumping Capacity

Engine-drive pumps shall meet the design pumping

requirements unless storage capacity is available for

flows in excess of pump capacity. Pumps shall be

designed for anticipated operating conditions, including

suction lift if applicable.

B) Operation

The engine and pump shall be equipped to provide

automatic start-up and operation of pumping equipment

unless manual start-up and operation is justified.

Provisions shall also be made for manual start-up.

Where manual start-up and operation is justified,

storage capacity and alarm system must meet the

requirements of subsection (d)(2)(C).

C) Portable Pumping Equipment

Where part or all of the engine-driven pumping equipment

is portable, sufficient storage capacity shall be

provided to allow time for detection of pump station

failure and transportation and hookup of the portable

equipment.

3) Engine-Driven Generating Equipment

Where permanently-installed or portable engine-driven

generating equipment is used, the following requirements

shall apply in addition to general requirements of subsection

(d)(1):

A) Generating Capacity

i) Generating unit size shall be adequate to provide

power for pump motor starting current and for

lighting, ventilation, and other auxiliary

equipment necessary for safety and proper operation

of the lift station.

ii) The operation of only one pump during periods of

auxiliary power supply must be justified. Such

justification may be made on the basis of the

design peak flows relative to single-pump capacity,

anticipated length of power outage, and storage

capacity.

iii) Special sequencing controls shall be provided to

start pump motors unless the generating equipment

has capacity to start all pumps simultaneously with

auxiliary equipment operating.

B) Operation

Provisions shall be made for automatic and manual

start-up and load transfer unless only manual start-up

and operation is justified. The generator must be

protected from operating conditions that would result in

damage to equipment. Provisions should be considered to

allow the engine to start and stabilize at operating

speed before assuming the load. Where manual start-up

and transfer is justified, storage capacity and alarm

system must meet the requirements of subsection

(d)(3)(C).

C) Portable Generating Equipment

Where portable generating equipment or manual transfer

is provided, sufficient storage capacity shall be

provided to allow time for detection of pump station

failure and transportation and connection of generating

equipment. The use of special electrical connections

and double throw switches are recommended for connecting

portable generating equipment.

4) Independent Utility Substations

Where independent substations are used for emergency power,

each separate substation and its associated transmission

lines must be capable of starting and operating the pump

station at its rated capacity.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

Sewage pumping stations and portable equipment shall be supplied with a

complete set of operational instructions, including emergency procedures,

maintenance schedules, tools and such spare parts as may be necessary.

a) Velocity and Diameter

At design pumping rates, a cleansing velocity of at least 2 feet

per second should be maintained. Lower velocities may be

permitted for very small installations. The minimum force main

diameter for raw sewage shall be 4 inches except for grinder pump

lift stations as allowed under Section 370.410(c)(3).

b) Air and Vacuum Relief Valve

An air relief valve shall be placed at high points in the force

main to prevent air locking. Vacuum relief valves may be

necessary to relieve negative pressure on force mains. Force main

configuration and head conditions shall be evaluated as to the

need for and placement of vacuum relief valves.

c) Termination

Force mains should enter the gravity sewer system at a point not

more than 2 feet above the flow line of the receiving manhole.

d) Design Pressure

The force mains and fittings, including reaction blocking, shall

be designed to withstand normal pressure and pressure surges

(water hammer). The need for surge protection chambers shall be

evaluated.

e) Special Construction

Force main construction near streams or water works structures and

at water main crossings shall meet applicable provisions of

Sections 370.125 and 370.126.

f) Design Friction Losses

1) Friction losses through force mains shall be based on the

Hazen and Williams formula or other acceptable methods. When

the Hazen and Williams formula is used, the value for "C"

shall be 100 for unlined iron or steel pipe for design. For

other smooth pipe materials such as polyvinyl chloride,

polyethylene or lined ductile iron, a higher "C" value not to

exceed 120 may be allowed for design.

2) When initially installed, force mains will have a

significantly higher "C" factor. The effect of the higher

"C" factor should be considered in calculating maximum power

requirements and duty cycle time to prevent damage to the

motor.

g) Identification

Where force mains are constructed of material which might cause

the force main to be confused with potable water mains, the force

main shall be appropriately identified.

h) Flexible Pipe Force Main Embedment

Embedment bedding (haunching and initial backfill as depicted in

ASTM D2321-89, Figure (1)) shall be in accordance with Section

20-2.21 A and 20.2.21 B of Standard Specifications for Water and

Sewer Main Construction in Illinois, 5th ed. (1996)(no later

editions or amendments).

i) Leakage Testing

Leakage testing shall be specified, including testing methods and

leakage limits.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

SUBPART E: SEWAGE TREATMENT WORKS

a) General

The following items shall be considered when selecting a plant

site:

1) Proximity to residential areas.

2) Direction of prevailing winds.

3) Necessary routing to provide accessibility by all weather

roads.

4) Area available for expansion.

5) Local zoning requirements.

6) Local soil characteristics, geology, and topography available

to minimize pumping.

7) Access to receiving stream.

8) Compatibility of treatment process with the present and

planned future land use, including noise, potential odors,

air quality, and anticipated sludge processing and disposal

techniques.

9) The requirements of the Illinois Groundwater Protection Act

[415 ILCS 55].

b) Critical Sites

Where a site must be used which is critical with respect to the

items in subsection (a), appropriate measures shall be taken to

minimize adverse impacts.

c) Flood Protection

The treatment works structures, electrical and mechanical

equipment shall be protected from physical damage by the maximum

100 year flood. Treatment works shall remain fully operational

during the 25 year flood. This requirement applies to new

construction and to existing facilities undergoing major

modification. Flood plain regulations of State and Federal

agencies shall be considered.

d) Plant Accessibility

All plant facilities shall be accessible by an all weather road.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

The required degree of wastewater treatment shall be established by

reference to applicable effluent and water quality standards contained in

35 Ill. Adm. Code Subtitle C, Chapter I unless more stringent limitations

have been established.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Type of Treatment

1) As a minimum, the following items shall be considered in the

selection of the type of treatment:

A) Present and future effluent requirements.

B) Location and local topography of the plant site.

C) The effects of industrial wastes likely to be

encountered.

D) Ultimate disposal of sludge.

E) System capital costs.

F) System operating and maintenance costs and basic energy

requirements.

G) Existing unit process performance and capacity.

H) Process complexity governing operating personnel

requirements.

I) Environmental impact on present and future adjacent land

use.

2) The plant design shall provide the necessary flexibility to

perform satisfactorily within the expected range of waste

characteristics and volumes.

b) Required Engineering Data for New Process Evaluation

1) The policy of the Agency is to encourage rather than obstruct

the development of any methods or equipment for treatment of

wastewaters. The lack of inclusion in these standards of

some types of wastewater treatment processes or equipment

should not be construed as precluding their use. The Agency

may approve other types of wastewater treatment processes and

equipment under the condition that the operational

reliability and effectiveness of the process or device shall

have been demonstrated with a suitably-sized prototype unit

operating at its design load conditions, to the extent

required.

2) To determine that such new processes and equipment have a

reasonable and substantial chance of success, the Agency will

require the following:

A) Monitoring observations, including test results and

engineering evaluations, demonstrating the efficiency of

such processes.

B) Detailed description of the test methods.

C) Testing, including appropriately-composited samples,

under various ranges of strength and flow rates

(including diurnal variations) and waste temperatures

over a sufficient length of time to demonstrate

performance under climatic and other conditions which

may be encountered in the area of the proposed

installations.

D) Other appropriate information.

3) The Agency will require that appropriate testing be conducted

and evaluations be made under the supervision of a competent

process engineer other than those employed by the

manufacturer or developer.

c) Design Loads

1) Hydraulic Design

A) New Systems

Plans for sewage treatment plants to serve new sewer

systems for municipalities or sewer districts shall be

based upon a design average daily flow of at least 100

gallons per capita, to which must be added industrial

waste volumes. The design also shall include

appropriate allowance for flow conditions determined

under Section 370.122.

B) Existing Systems

Where there is an existing sewer system, the volume and

rates of the existing sewage flows shall be determined.

The determination shall include both dry weather and wet

weather flows. At least one year's flow data should be

used to determine the design flows that are defined in

Section 370.220.

C) Treatment Plant Design Capacity

The treatment plant capacity shall be rated on the

design average flow, selected after any sewer system

rehabilitation, plus appropriate future growth. The

design of treatment units that are not subject to peak

flow requirements shall be based on the design average

flow. For plants subject to high wet weather flows or

overflow detention pumpback flows, the design maximum

flow that the plant is to treat on a sustained basis

must be specified.

2) Organic Design

A) New Systems Minimum Design

i) Domestic waste treatment design shall be on the

basis of at least 0.17 pounds of biochemical oxygen

demand (BOD5) per capita per day and 0.20 pounds of

suspended solids per capita per day.

ii) When garbage grinders are used in areas tributary

to a domestic treatment plant, the design basis

should be increased to 0.22 pounds of BOD5 and

0.25 pounds of suspended solids per capita per

day.

iii) Domestic waste treatment plants that will receive

industrial wastewater flows shall be designed to

include these industrial waste loads.

B) Existing Systems

When an existing treatment works is to be upgraded or

expanded, organic design shall be based upon the actual

strength of the wastewater as determined from

measurements taken in accordance with subsection

(c)(1)(B), with an appropriate increment for growth as

determined under the provisions of subsection (c)(2)(A).

3) Shock Effects

Domestic waste treatment designs shall consider and take into

account the shock effect of high concentrations and diurnal

peaks for short periods on the treatment process,

particularly for small waste treatment plants serving

institutions, restaurants, schools, etc.

4) Design by Analogy

Data from similar existing systems may be utilized in the

case of new systems; however, thorough investigation and

adequate documentation shall be made to establish the

reliability and applicability of such data.

d) Conduits

1) All piping and channels shall be designed to carry the

maximum expected flows. The incoming sewer shall be designed

for unrestricted flow. Bottom corners of the channels must

be filleted. Conduits shall be designed to avoid creation of

pockets and corners where solids can accumulate.

2) Suitable gates should be placed in channels to seal off

unused sections which might accumulate solids. The use of

shear gates is permitted where they can be used in place of

gate valves or sluice gates. Non-corrodible materials shall

be used for these control gates.

e) Arrangement of Units

Component parts of the plant should be arranged for greatest

operating convenience, flexibility, economy, continuity of maximum

effluent quality, and so as to facilitate installation of future

units.

f) Flow Division Control

Flow division control facilities shall be provided as necessary to

insure organic and hydraulic loading control to plant process

units and shall be designed for easy operator access, change,

observation, and maintenance. The use of head boxes equipped with

sharp-crested weirs or similar devices are recommended. The use

of valves for flow splitting is not acceptable. Appropriate flow

measurement shall be incorporated in the flow division control

design.

g) Load Equalization and Attenuation

1) Equalization of hydraulic and organic loads to downstream

treatment units is recommended where the peak hourly load

exceeds 300% of the design average load. Particular

attention shall be given to equalization of pumped flows to

limit hydraulic surges on downstream units.

2) Plants proposed to receive sewage wastes from only

institutions (motels, schools, hospitals, nursing homes,

etc.) or industries which discharge substantially the total

flow in 12 hours or less, shall be designed to include flow

equalization. Where flow equalization facilities are

provided, the design shall include adequate aeration and

mixing equipment to prevent septicity.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Installation of Mechanical Equipment

The specifications shall be so written that the installation and

initial operation of major items of mechanical equipment will be

inspected and approved by a representative of the manufacturer.

b) Bypasses

Properly located and arranged bypass structures and piping shall

be provided so that each unit of the plant can be removed from

service independently. The bypass design shall facilitate plant

operation during unit maintenance and emergency repair so as to

minimize deterioration of effluent quality and insure rapid

process recovery upon return to normal operational mode.

c) Unit Bypass and Wastewater Pumpage During Construction

Final plans and specifications for upgrading or expanding existing

treatment plants shall include construction scheduling of any unit

bypassing, and appropriate temporary wastewater pumpage acceptable

to the Agency to minimize temporary water quality degradation.

Refer to Section 370.260.

d) Drains and Buoyancy Protection

1) Means shall be provided to dewater each unit. Pipes subject

to clogging shall be provided with means for mechanical

cleaning or flushing.

2) Due consideration should be given to the possible need for

hydrostatic pressure relief devices to prevent flotation of

structures.

e) Construction Materials

Due consideration should be given to the selection of materials

which are to be used in sewage treatment works because of the

possible presence of hydrogen sulfide and other corrosive gases,

greases, oils, and similar constituents frequently present in

sewage. This is particularly important in the selection of metals

and paints. Dissimilar metals should be avoided to minimize

galvanic action.

f) Painting

The use of paints containing mercury should be avoided. In order

to facilitate identification of piping, particularly in the large

plants, it is suggested that the different lines be color coded.

The following color scheme is recommended for purposes of

standardization:

1) Sludge line - brown

2) Gas line - orange

3) Potable water line - blue

4) Non-potable water line - blue with 3 inch yellow band spaced

30 inches apart

5) Chlorine line - yellow

6) Sewage line - gray

7) Compressed air line - green

8) Water lines for heating digesters or buildings - blue with a

6-inch red band spaced 30 inches apart

9) Sulfur dioxide line - yellow with red bands.

10) The contents shall be stenciled on the piping, labeling the

contents in a contrasting color.

g) Operating Equipment

A complete outfit of tools, accessories (such as portable pump and

ventilation blowers, etc.), and spare parts necessary for the

plant operators use shall be provided. Readily accessible storage

space and work bench facilities shall be provided. Consideration

shall be given to provision of a garage storage area for large

equipment storage, maintenance, and repair.

h) Erosion Control During Construction

Effective site erosion control shall be provided during

construction.

i) Grading and Landscaping

Upon completion of the plant, the ground should be graded and

seeded. Concrete or gravel walkways should be provided for access

to all units. Where possible, steep slopes should be avoided to

prevent erosion. Surface water shall not be permitted to drain

into any unit. Particular care shall be taken to protect

trickling filter beds, sludge beds, and intermittent sand filters

from storm water runoff. Landscaping shall be provided when a

plant must be located near residential areas.

j) Confined Spaces

The number of confined spaces should be minimized for safety

purposes.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Discharge Impact Control

The outfall sewer shall be designed to discharge to the receiving

stream in a manner acceptable to the Agency. Consideration

should be given in each case to the following:

1) Preference for free fall or submerged discharge at the site

selected.

2) Utilization of cascade aeration of effluent discharge to

increase dissolved oxygen.

3) Limited or complete across-stream dispersion as needed to

protect aquatic life movement and growth in the immediate

reaches of the receiving stream.

b) Design and Construction

The outfall sewer shall be so constructed and protected against

the effects of flood water, waves, ice, or other hazards as to

reasonably insure its structural stability and freedom from

stoppage. A manhole should be provided at the shore end of all

gravity sewers extending into the receiving waters. Hazards to

navigation shall be considered in designing outfall sewers.

c) Sampling Provisions

All outfalls shall be designed so that a sample of the effluent

can be readily obtained at a point after the final treatment

process and before discharge to or mixing with the receiving

waters.

a) Emergency Power or Pumping Facilities

1) All plants shall be provided with an alternate source of

electric power or pumping capability to allow continuity of

operation during power failures. Methods of providing power

or pumping capability include:

A) The connection to at least 2 independent public utility

sources such as substations. A power line from each

substation into the treatment plant with capability for

switchover to the second power source by plant operating

personnel will be required.

B) Portable or in place internal combustion engine

equipment which will generate electrical or mechanical

energy. Refer to Section 370.136(d).

C) Portable pumping equipment when only emergency pumping

is required. Refer to Section 370.136(d).

2) Standby Generating Capacity Requirements

Standby generating capacity normally is not required for

aeration equipment used in the activated sludge process. In

cases where a history of long term (4 hours or more) power

outages have occurred, auxiliary power for minimum aeration

of the activated sludge will be required.

3) Degree of Treatment Required

No reduction in degree of treatment due to power outages will

be allowed when the wastewater is to be treated by

installations using trickling filters, waste stabilization

ponds and/or other low energy usage treatment devices.

4) Continuity of Disinfection

The design shall provide for continuous disinfection during

all power outages, if required due to critical outfall

locations and receiving waters.

5) Continuity of Dechlorination

For facilities using dechlorination equipment, the design

shall provide for continuous dechlorination during all power

outages, if required due to critical outfall locations and

receiving waters.

b) Water Supply

1) General

An adequate supply of potable water under pressure should be

provided for use in the laboratory and general cleanliness

around the plant. No piping or other connections shall exist

in any part of the treatment works which, under any

conditions, might cause the contamination of a potable water

supply.

2) Direct Connections

A) Potable water from a municipal or separate supply may be

used directly at points above grade for the following

hot and cold supplies:

i) Lavatory sink

ii) Water closet

iii) Laboratory sink (with vacuum breaker)

iv) Shower

v) Drinking fountain

vi) Eye wash fountain

vii) Safety shower

viii) Fire protection sprinklers

B) Hot water for any of the above units shall not be taken

directly from a boiler used for supplying hot water to a

sludge heat exchanger or digester heating unit.

3) Indirect Connections

A) Where a potable water supply is to be used for any

purpose in a plant other than those listed in subsection

(b)(2)(A), a break tank, pressure pump and pressure tank

shall be provided. Water shall be discharged to the

break tank through an air-gap at least 6 inches above

the maximum flood line or the spill line of the tank,

whichever is higher. A sketch of an acceptable break

tank is contained in Appendix G, Figure No. 4. In-line

backflow preventers are not acceptable.

B) A sign shall be permanently posted at every hose bib,

faucet, or sill cock located on the water system beyond

the break tank to indicate that the water is not safe

for drinking.

4) Separate Potable Water Supply

Where it is not possible to provide potable water from a

public water supply, a separate well may be provided.

Location and construction of the well should comply with

requirements of the governing State and local regulations.

Requirements governing the use of the supply are those

contained in subsections (b)(2) and (b)(3).

5) Separate Non-Potable Water Supply

Where a separate non-potable water supply is to be provided,

a break tank will not be necessary, but all sill cocks and

hose bibs shall be posted with a permanent sign indicating

the water is not safe for drinking.

c) Sanitary Facilities

Toilet, shower, and lavatory should be provided in sufficient

numbers and at convenient locations to serve the expected plant

personnel.

d) Floor Slope

Floor surfaces shall be sloped adequately to a point of drainage.

e) Stairways

Stairways shall be installed in lieu of ladders for access to

those units requiring inspection and maintenance, including but

not limited to trickling filters, digesters, aeration tanks,

clarifiers and tertiary filters. Spiral or winding stairs are

permitted only for secondary access where dual means of egress are

provided. Stairways shall have slopes between 30 and 40 degrees

from the horizontal to facilitate carrying samples, tools, etc.

Each tread and riser shall be of uniform dimension in each flight.

Minimum tread run shall not be less than 9 inches. The sum of the

tread run and riser shall not be less than 17 nor more than 18

inches. A flight of stairs shall consist of not more than a 12

foot continuous rise without a platform.

f) Flow Measurement

1) Flow measurement facilities shall be provided so as to

measure the following flows:

A) Plant effluent flow.

B) Plant influent flow, if significantly different from

plant effluent flow, such as for lagoons and plants with

excess flow storage or flow equalization.

C) Excess flow treatment facility discharges.

D) Other flows required to be monitored under the

provisions of an NPDES discharge permit.

E) Flows required for plant operational control, including

but not limited to return activated sludge flow, waste

activated sludge flow, recirculation flow and recycle

flows.

2) Indicating, totalizing and recording flow measurement devices

shall be provided for all mechanical plants for all flows

except those specified in subsection (f)(1)(E) above. Flow

measurement equipment for lagoon systems shall consist of, at

a minimum, elapsed time meters used in conjunction with

pumping rate test or calibrated weirs. All flow measurement

equipment must be sized to function effectively in the full

range of flows expected and shall be protected against

freezing.

3) Flow measurement equipment including entrance and discharge

conduit configuration and critical control elevations shall

be designed to ensure that the required hydraulic conditions

necessary for accurate measurement are provided. Conditions

that must be avoided include turbulence, eddy currents, air

entrainment, etc., that upset the normal hydraulic conditions

that are necessary.

g) Sampling Equipment

Effluent composite sampling equipment shall be provided at all

mechanical plants and at other facilities where necessary to meet

discharge permit monitoring requirements.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Adequate provision shall be made to effectively protect the

operator and visitors from hazards. The following shall be

provided to fulfill the particular needs of each plant:

1) Enclosure of the plant site with a fence designed to

discourage the entrance of unauthorized persons and animals.

2) Installation of hand rails and guards around all tanks, pits,

stairwells, and other hazardous structures.

3) Provision of first aid equipment at marked locations.

4) Posting of "No Smoking" signs in hazardous areas.

5) Protective clothing and equipment such as air packs, goggles,

gloves, hard hats, safety harnesses and hearing protection.

6) Provision of portable blower and sufficient hose.

7) Portable lighting equipment that complies with the National

Electrical Code.

8) Appropriately placed warning signs for slippery areas,

non-potable water fixtures, low head clearance areas, open

service manhole, hazardous chemical storage areas, flammable

fuel storage areas, etc.

9) Smoke and fire detectors, fire extinguishers, and appropriate

waste receptacles.

10) Provisions for confined space entry in accordance with the

requirements of the Occupational Safety and Health Act and

any other applicable regulatory requirements.

b) Hazardous Chemical Handling

1) Containment Materials

The materials utilized for storage, piping, valves, pumping,

metering, splash guards, etc., shall be specially selected

considering the physical and chemical characteristics of each

hazardous or corrosive chemical.

2) Secondary Containment and Storage

A) Wet and Dry Chemicals

Chemical storage areas shall be enclosed in dikes or

curbs which will contain the stored volume until it can

be safely transferred to alternate storage or released

to the wastewater at controlled rates which will not

damage facilities, inhibit the treatment processes, or

contribute to stream pollution. Liquid polymer should

be similarly contained to reduce areas with slippery

floors, especially to protect travelways. Non-slip

floor surfaces are desirable in polymer handling areas.

B) Liquified Gas Chemicals

Chlorine and sulfur dioxide cylinder and container

storage shall meet the requirements of Sections 370.1020

and 370.1040. Ammonia gas cylinder isolation shall be

provided. Gas cylinder storage facilities shall be

equipped with appropriate alarm system and emergency

repair equipment and control system.

3) Eye Wash Fountains and Safety Showers

A) Eye wash fountains and safety showers utilizing potable

water shall be provided in the laboratory and on each

floor level or work location involving hazardous or

corrosive chemical storage, mixing (or slaking),

pumping, metering, or transportation unloading. These

facilities are to be as close as practical to possible

chemical exposure sites and are to be fully useful

during all weather conditions. The eye wash fountains

shall be supplied with water of moderate temperature

(50 - 90 Fahrenheit (F)), separate from the hot water

supply, suitable to provide 15 minutes to 30 minutes of

continuous irrigation of the eyes.

B) The emergency showers shall be capable of discharging 30

to 50 gallons per minute (gpm) of water at moderate (50

- 90 F) temperature at pressures of 20 to 50 pounds

per square inch (psi). The eye wash fountains and

showers shall be no more than 25 feet from points of

caustic exposure.

4) Splash Guards

All pumps or feeders for hazardous or corrosive chemicals

shall have guards which will effectively prevent spray of

chemicals into space occupied by personnel. The splash

guards are in addition to guards to prevent injury from

moving or rotating machinery parts.

5) Piping, Labeling, Coupling Guards, Location

A) All piping containing or transporting corrosive or

hazardous chemicals shall be identified with labels

every ten feet and with at least two labels in each

room, closet, or pipe chase. Color coding may also be

used, but is not an adequate substitute for labeling.

B) All connections (flanged or other type), except adjacent

to storage or feeder areas, shall have guards which will

direct any leakage away from space occupied by

personnel. Pipes containing hazardous or corrosive

chemicals should not be located above shoulder level

except where continuous drip collection trays and

coupling guards will eliminate chemical spray or

dripping onto personnel.

6) Protective Clothing and Equipment

The following items of protective clothing or equipment shall

be available and utilized for all operations or procedures

where their use will minimize injury hazard to personnel:

A) Air pack breathing apparatus for protection against

chlorine and other toxic gases.

B) Chemical workers' goggles or other suitable goggles.

(Safety glasses are insufficient.)

C) Face masks or shields for use over goggles.

D) Dust masks to protect the lungs in dry chemical areas.

E) Rubber gloves.

F) Rubber aprons with leg straps.

G) Rubber boots (leather and wool clothing should be

avoided near caustics).

H) Safety harness and line.

7) Warning Systems and Signs

A) Facilities shall be provided for automatic shutdown of

pumps and sounding of alarms when failure occurs in a

pressurized chemical discharge line.

B) Warning signs requiring use of goggles and dust masks

shall be located near chemical unloading stations,

pumps, and other points of frequent hazard.

8) Dust Collection

Dust collection equipment shall be provided where dry

chemicals are stored or used to protect personnel from dusts

injurious to the lungs or skin and to prevent polymer dust

from settling on walkways which become slick when wet.

9) Container Identification

The identification and hazard warning data included on

shipping containers, when received, shall appear on all

containers (regardless of size or type) used to store, carry,

or use a hazardous substance. Sewage and sludge sample

containers should be adequately labeled. Below is a suitable

label to identify a sewage sample as a hazardous substance:

Sample Point No. <P >>

Contains Harmful Bacteria.

May contain hazardous or

toxic material.

Do not drink or swallow.

Avoid contact with openings

or breaks in the skin.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) All treatment works shall include a laboratory for making the

necessary analytical determinations and operating control tests,

except for those plants utilizing only processes not requiring

laboratory testing for plant control and satisfactory off-site

laboratory provisions are made to meet the permit monitoring

requirements. For plants where a fully equipped laboratory is not

required, the requirements for utilities and equipment such as

fume hoods may be reduced or omitted.

b) The laboratory shall have sufficient size, bench space, equipment

and supplies to perform all self-monitoring analytical work

required by discharge permits, and to perform the process control

tests necessary for good management of each treatment process

included in the design.

c) The facilities and supplies necessary to perform analytical work

to support industrial waste control programs will normally be

included in the same laboratory. The laboratory size and

arrangement must be sufficiently flexible and adaptable to

accomplish these assignments. The layout should consider future

needs for expansion in the event that more analytical work is

needed.

d) Location and Space

1) The laboratory should be located on ground level, easily

accessible to all sampling points, with environmental control

as an important consideration. It shall be located in a

separate room or building away from vibrating machinery or

equipment which might have adverse effects on the performance

of laboratory instruments or the analyst, or shall be

designed to prevent structural transmission of machine

vibration. The floor and wall construction shall be

designed to keep out machine noise (blowers, pumps, etc.).

The following minimum conditions shall be met:

A) Blowers, pumps, etc., must be located on a separate

floor pad.

B) Common walls between machinery rooms must be

double-walled with sound insulation between the walls.

Connecting doors or windows to machinery rooms are not

acceptable.

C) Common attic space shall be blocked off and effective

sound proof material provided in the ceiling.

2) A minimum of 400 square feet of floor space should be

allocated for the laboratory. Less space may be allowed if

the sampling and analysis program, approved by the Agency,

does not require a full-time laboratory chemist. If more

than two persons normally will be working in the laboratory

at any given time, 100 square feet of additional space should

be provided for each additional person. Bench-top working

surface should occupy at least 35 percent of the total floor

space.

3) Minimum ceiling height should be 8 feet 6 inches. If

possible, this height should be increased to provide for the

installation of wall-mounted water stills, distillation

racks, and other equipment with extended height requirements.

4) Additional floor and bench space should be provided to

facilitate performance of analysis of industrial wastes, as

required by the discharge permit and the utilities industrial

waste pretreatment program. The above minimum space does not

provide office or administration space.

e) Materials

1) Ceilings

Acoustical tile should be used for ceilings except in high

humidity areas where they should be constructed of cement

plaster. Materials containing asbestos shall not be used.

2) Walls

For ease of maintenance and a pleasant working environment,

light-colored ceramic tile should be used from floor to

ceiling for all interior walls.

3) Floors

Floor surface materials shall be fire resistant and highly

resistant to acids, alkalies, solvents, and salts.

4) Doors

A) Two exit doors should be located to permit a straight

egress from the laboratory, preferably at least one to

outside the building. Panic hardware should be used.

They should have large glass windows for easy visibility

of approaching or departing personnel.

B) Automatic door closers should be installed; swinging

doors should not be used.

C) Flush hardware should be provided on doors if cart

traffic is anticipated. Kick plates are also

recommended.

f) Cabinets and Bench Tops

1) Cabinets

A) Wall-hung cabinets are useful for dust-free storage of

instruments and glassware.

B) Units with sliding glass doors are preferable. They

should be hung so the top shelf is easily accessible to

the analyst. Thirty inches from the bench top is

recommended.

C) One or more cupboard-style base cabinets should be

provided for storing large items; however, drawer units

are preferred for the remaining cabinets. Drawers

should slide out so that entire contents are easily

visible. They should be provided with rubber bumpers

and with stops which prevent accidental removal.

Drawers should be supported on ball bearings or nylon

rollers which pull easily in adjustable steel channels.

All metal drawer fronts should be double-wall

construction. All cabinet shelving should be acid

resistant and adjustable from inside the cabinet.

2) Bench Tops

Generally, bench-top height should be 36 inches. However,

areas to be used exclusively for sit-down type operations

should be 30 inches high and include kneehole space.

One-inch overhangs and drip grooves should be provided to

keep liquid spills from running along the face of the

cabinet. Tops should be furnished in large sections, 1 1/4

inches thick. They should be field joined into a continuous

surface with acid, alkali, and solvent-resistant cements

which are at least as strong as the material of which the top

is made.

3) Utility Accessories

Water, gas, air, and vacuum service fixtures; traps,

strainers, overflows, plugs and tailpieces; and all

electrical service fixtures shall be supplied with the

laboratory furniture.

g) Hoods

Fume hoods to promote safety and canopy hoods over heat-releasing

equipment shall be installed.

1) Fume Hoods

A) Location

i) Fume hoods should be located where air disturbance

at the face of the hood is minimal. Air

disturbance may be created by persons walking past

the hood; by heating, ventilating or

air-conditioning systems; by drafts from opening or

closing a door; etc.

ii) Safety factors should be considered in locating a

hood. If a hood is situated near a doorway, a

secondary means of egress must be provided. Bench

surfaces should be available next to the hood so

that chemicals need not be carried long distances.

B) Design and Materials

i) The selection of fume hoods, their design and

materials of construction, must be made by

considering the variety of analytical work to be

performed and the characteristics of the fumes,

chemicals, gases, or vapors that will or may be

released. Special design and construction is

necessary if perchloric acid use is anticipated.

Consideration should be given for providing more

than one fume hood to minimize potential hazardous

conditions throughout the laboratory.

ii) Fume hoods are not appropriate for operation of

heat-releasing equipment that does not contribute

to hazards, unless they are provided in addition to

those needed to perform hazardous tasks.

C) Fixtures

i) One cup sink should be provided inside each fume

hood.

ii) All switches, electrical outlets, and utility and

baffle adjustment handles should be located outside

the hood. Light fixtures should be

explosion-proof.

D) Exhaust

Continuous duty exhaust capability should be provided.

Exhaust fans should be explosion-proof. Exhaust

velocities should be checked when fume hoods are

installed.

E) Alarms

A buzzer for indicating exhaust fan failure and a static

pressure gauge should be placed in the exhaust duct. A

high temperature sensing device located inside the hood

should be connected to the buzzer.

2) Canopy Hoods

Canopy hoods should be installed over the bench-top areas

where hot plate, steam bath, or other heating equipment or

heat-releasing instruments are used. The canopy should be

constructed of steel, plastic, or equivalent material, and

finished with enamel to blend with other laboratory

furnishings.

h) Sinks

1) The laboratory should have a minimum of 3 sinks (not

including cup sinks). At least 2 of them should be

double-well with drainboards. Additional sinks should be

provided in separate work areas as needed, and identified for

the use intended.

2) Waste openings should be located toward the back so that a

standing overflow will not interfere. All water fixtures on

which hoses may be used should be provided with reduced zone

pressure backflow preventers to prevent contamination of

water lines.

3) The sinks should be constructed of material highly resistant

to acids, alkalies, solvents, and salts, and should be

abrasion and heat resistant, non-absorbent, light in weight

and have all appropriate characteristics for laboratory

applications. Traps should be made of glass, plastic, or

lead and easily accessible for cleaning.

i) Ventilation and Lighting

1) Laboratories shall be separately air conditioned and

dehumidification shall be provided where laboratory control

tests procedures will be affected by high humidity

conditions. Separate exhaust ventilation outlet locations

(fume and heat hoods, room air, etc.) shall be provided

remote from ventilation intakes.

2) Adequate lighting, free from shadows, shall be provided to

permit reading of laboratory instrument dials, glassware

calibrations, etc.

j) Gas and Vacuum

1) Natural or bottled gas should be supplied to the laboratory.

Digester gas should not be used.

2) An adequately-sized line source of vacuum should be provided

with outlets available throughout the laboratory.

k) Balance and Table

An analytical balance of the automatic, digital readout, single

pan, 0.1 milligram sensitivity type shall be provided. A heavy

special-design balance table which will minimize vibration of the

balance shall be provided. It shall be located as far as

practical from windows, doors, or other sources of drafts or air

movements, so as to minimize undesirable impacts from these

sources upon the balance.

l) Equipment, Supplies and Reagents

The laboratory shall be provided with all of the equipment,

supplies, and reagents that are needed to carry out all of the

facility's analytical testing requirements. Discharge permit,

process control, and industrial waste monitoring requirements

must be considered when specifying equipment needs. References

such as Standard Methods and the USEPA Analytical Procedures

Manual should be consulted prior to specifying equipment items.

m) Power Supply Regulation

1) To eliminate voltage fluctuation, electrical lines supplying

the laboratory should be controlled with a constant voltage,

harmonic neutralized type of transformer. This transformer

should contain less than 3% total root mean square (rms)

harmonic content in the output, should regulate to <P+>>1% for an

input range of <P+>>15% of nominal voltage, with an output of 118

volts. For higher voltage requirements, the 240-volt lines

should be similarly regulated.

2) Electrical devices in the laboratory not requiring a

regulated supply (i.e., ordinary resistance heating devices)

that are non-portable may be wired to an unregulated supply.

n) Laboratory Grade Water Source

A laboratory grade water source, with at least one gallon per hour

capacity, shall be installed complete with all utility

connections. The type of treatment used to produce laboratory

grade water shall be based on the quality of water required for

the tests to be performed at the plant. Laboratory water

treatment devices shall be constructed of materials that are

compatible with the water to be treated and produced.

o) Laboratory Safety Equipment

Laboratory safety equipment shall be provided in accordance with

the requirements of Section 370.560(a)(3), (a)(9), (b)(3) and

(b)(6).

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

SUBPART F: PRELIMINARY TREATMENT

a) Safety

Safety Features Relative to Location

1) Railings and Gratings

A) Manually cleaned channels shall be protected by guard

railings and deck gratings, with adequate provisions for

removal or opening to facilitate raking.

B) Mechanically cleaned channels shall be protected by

guard railings and deck gratings. Consideration should

also be given to temporary access arrangements to

facilitate maintenance and repair.

2) Mechanical Devices

A) Mechanical screening equipment shall have adequate

removable enclosures to protect personnel against

accidental contact with moving parts and to prevent

dripping in multi-level installations.

B) A positive means of locking out each mechanical device

shall be provided.

3) Units and Equipment in Deep Pits

Manually cleaned screens located in pits deeper than 4 feet

shall be provided with stairway access, adequate lighting and

ventiliation, and convenient and adequate means for removing

screenings. Access ladders may be used instead of steps in

pits less than 4 feet deep. Hoisting or lifting equipment

shall be used where necessitated by the depth of the pit or

the amount of material to be removed.

4) In Buildings

Units and equipment installed in buildings where other

equipment or offices are located shall be isolated from the

rest of the building, and shall be provided with separate

outside entrances and separate and independent means of

ventilation.

5) Ventilation

A) Adequate ventilation shall be provided for installations

described in subsections (a)(3) and (4). Ventilation

may either be continuous or intermittent. If

continuous, ventilation shall provide at least 12

complete air changes per hour; if intermittent,

ventilation shall provide at least 30 complete air

changes per hour.

B) Where the pit is deeper than 4 feet mechanical

ventilation is required, and the air shall be forced

into the screen pit area rather than exhausted from the

screen pit. The maximum distance from the fresh air

discharge and the working deck floor shall be 24 inches.

Dampers should not be used on fresh air ducts.

Obstructions in air ducts should be avoided to prevent

clogging. Air intake screens (bird and insect) shall be

located so as to be easily accessible for cleaning.

C) Switches for operation of ventilation equipment should

be marked and located at the entrance to the screen pit

area. All intermittently operated ventilating equipment

shall be interconnected with the respective lighting

system. Consideration should be given to automatic

controls where intermittent operation is used. The

manual lighting-ventilation switch shall override the

automatic controls.

D) The fan wheel shall be fabricated from non-sparking

material. Refer to Section 370.610(a)(3)(C) for motor

and electrical requirements.

6) Electrical Fixtures

Electrical fixtures and controls in enclosed places where gas

may accumulate shall comply with Section 370.610(a)(3)(C).

b) Communition

Communition or other in-stream shredding of sewage solids shall be

followed by primary settling or fine screening devices to remove

the shredded stringy materials prior to the activated sludge

process to minimize operational problems associated with

reaglomeration of stringy materials.

c) Channels

Channels shall be equipped with the necessary gates to divert flow

from any one unit. Provisions must also be made for dewatering

each unit. Channels preceding and following screens shall be

shaped and filleted as necessary to eliminate settling of solids.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Bar Racks and Screens

1) Where Required

Screening of raw sewage shall be provided at all mechanical

treatment works. For lift station applications, see Subpart

2) Design and Installation

A) Manually Cleaned Screens

Clear openings for manually cleaned screens between bars

should be from 1 to 1 3/4 inches. Design and

installation shall be such that they can be conveniently

cleaned. An accessible platform shall be provided on

which the operator may rake screenings easily and

safely. Suitable drainage facilities with return flow

to process shall be provided for the platform.

B) Mechanical Screens

Clear openings for mechanically cleaned screens may be

as small as practical to assure the proper operation and

maintenance of treatment facilities. Mechanical screens

shall be located so as to be protected from freezing and

to facilitate maintenance.

C) Velocities Through Screens

For manually or mechanically raked bar screens the

maximum velocities during peak flow periods should not

exceed 2.5 feet per second. The velocity shall be

calculated from a vertical projection of the screen

openings on the cross-sectional area between the invert

of the channel and the flow line. Excessive head loss

through the screen, which may affect upstream flow

measurement or bypassing, shall be taken into account.

D) Invert

The screen channel invert shall be at least 3 inches

below the invert of the incoming sewers. To prevent

jetting action, the length and/or construction of the

screen channel shall be adequate to reestablish

hydraulic flow pattern following the drop in elevation.

E) Slope

Manually cleaned screens should be placed on a slope of

30 to 45 degrees with the horizontal.

3) Control Systems

A) Timing Devices

All mechanical units which are operated by timing

devices should be provided with auxiliary controls which

will set the cleaning mechanism in operation at

predetermined high water marks.

B) Manual Override

Automatic controls shall be supplemented by a manual

override.

C) Electrical Fixtures and Controls

Electrical fixtures and controls in enclosed places

where gas may accumulate shall comply with the National

Electrical Code requirements for Class I, Group D,

Division I locations.

4) Disposal of Screenings

A) Amply-sized, vector-proof facilities shall be provided

for removal, handling and storage of screenings in a

sanitary manner. Suitable drainage facilities shall be

provided for the storage areas with drainage returned to

process. The return of ground screenings to the sewage

flow is unacceptable.

B) Disposal shall be in accordance with 35 Ill. Adm. Code

700 and shall be discussed in the plan documents.

b) Auxiliary Screens

Where mechanically operated screening is used, auxiliary manually

cleaned screens shall be provided. Design shall include

provisions for automatic diversion of the entire sewage flow

through the auxiliary screens should the regular units fail.

Refer to subsection (a)(2).

c) Fine Screens

Fine screens may be used in lieu of primary sedimentation

providing that subsequent treatment units are designed on the

basis of anticipated screen performance. Fine screens should not

be considered equivalent to primary sedimentation. Where fine

screens are used, additional removal of floatable oils and greases

shall be provided if they will adversely affect the function of

downstream treatment units.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Where Required

Grit removal facilities should be provided for all sewage

treatment plants and are required for plants receiving sewage from

combined sewers or from sewer systems receiving substantial

amounts of grit. If a plant serving a separate sewer system is

designed without grit removal facilities, the design shall include

provision for future installation. Consideration shall be given

to possible damaging effects on pumps, and other preceding

equipment, and the need for additional storage capacity in

treatment units where grit is likely to accumulate.

b) Location

Grit removal facilities should be located ahead of pumps. In such

cases, coarse bar racks should be placed ahead of mechanically

cleaned grit removal facilities. Comminution equipment, when used,

shall be located downstream of the grit facility in order to

reduce the operation and maintenance problems associated with

grit.

c) Type and number of units

1) The selection of the type of grit removal shall be based on

necessary flexibility of velocity control to remove the

selected size grit particulates through the range of expected

plant flows, the volume of grit expected, and available area

and hydraulic gradient limits at the site. Aerated or area

type grit removal units equipped with adequate controls for

operational flexibility are recommended where flow rates and

grit characteristics and volume are expected to vary widely.

2) Plants treating wastes from combined sewers shall have at

least one, preferably two or more, mechanically cleaned grit

removal units, with provision for unit bypassing. A single

manually cleaned or mechanically cleaned grit chamber with

unit bypass is acceptable for small sewage treatment plants

serving separate sanitary sewer systems. Minimum facilities

for larger plants serving separate sanitary sewers shall be

at least one mechanically cleaned unit with a unit bypass.

d) Design Factors

1) Channel Type Units

A) Turbulence Control

The equipment and inlet and outlet structures shall be

designed to minimize turbulance throughout the channel.

B) Velocity and Detention

Channel-type chambers shall be designed to provide

controlled velocities as close as possible to 1 foot per

second. The detention period shall be based on the size

of particle to be removed.

2) Aerated Units

A) Inlet

The inlet shall be located and arranged to prevent short

circuiting to the outlet and oriented to the unit flow

pattern so as to provide for adequate scouring

segregation of organic and grit materials prior to

discharge.

B) Detention

A detention time of at least 3 minutes at design peak

flow should be provided.

C) Air Supply

Air should be supplied at 5 cubic feet per minute (cfm)

per foot of tank length. The rate of air supplied shall

be widely variable so as to maximize unit process

effectiveness.

3) Grit Washing and Freeze Protection

All facilities not provided with positive velocity control

should include means for grit washing to further separate

organic and inorganic materials. Grit elevator and washing

facilities shall be housed to prevent freezing. Provision

for adequate heating and ventilation shall be provided to

prevent corrosion.

4) Drains

Provisions should be made for dewatering each unit.

5) Water

An adequate supply of water under pressure shall be provided

for clean up.

e) Grit Removal

Grit removal facilities located in pits shall be provided with

mechanical equipment for pumping or hoisting grit to ground level.

Pits deeper than 4 feet shall be provided with stairway access. An

approved-type elevator or manlift may be desirable in some

locations. Adequate ventilation, as described in Section

370.600(a)(5), and lighting shall be provided for pits that are

deeper than 4 feet or are within an enclosed area.

f) Grit Handling

Impervious, non-slip, working surfaces with drains back to process

shall be provided for grit handling areas. Safety handrails shall

be provided around the working platform areas. If grit is to be

transported, the conveying equipment shall be designed to avoid

loss of material and protection from freezing. Grit disposal

methods shall be in compliance with 35 Ill. Adm. Code 700 and

shall be described in the plan documents.

g) Electrical

All electrical fixtures and controls in enclosed or below grade

grit removal areas where hazardous gases may accumulate shall meet

the requirements of the National Electrical Code (1996) for Class

1, Group D, Division 1 locations.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

Pre-aeration of sewage to reduce septicity may be required in special

cases.

(Source: Added at 21 Ill. Reg. 12444, effective August 28, 1997)

SUBPART G: SETTLING

a) Number of Units

Multiple units capable of independent operation are desirable and

shall be provided in all plants where design average flows exceed

100,000 gallons per day. Plants not having multiple units shall

include other provisions to assure continuity of treatment.

b) Arrangement

Settling tanks shall be arranged in accordance with Sections

370.520(e) and 370.710(g).

c) Flow Distribution

Effective flow splitting devices and control appurtenances shall

be provided to insure proper organic and hydraulic proportion of

flow to each unit. Refer to Section 370.520(f).

d) Tank Configuration

Consideration should be given to the probable flow pattern in the

selection of tank size and shape, and inlet and outlet type and

location.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Dimensions

The minimum length of flow from inlet to outlet should be 10 feet

unless special provisions are made to prevent short circuiting.

The sidewater depth for primary clarifiers shall be as shallow as

practicable, but not less than 7 feet. Clarifiers following the

activated sludge process shall have sidewater depths of at least

12 feet to provide adequate separation zone between the sludge

blanket and the overflow weirs. Clarifiers following fixed film

reactors shall have sidewater depth of at least 7 feet.

b) Surface Settling Rates (Overflow Rates)

The hydraulic design of settling tanks shall be based on the

anticipated peak hourly flow.

1) Primary and Bypass Settling Tanks

A) Primary Settling

Some indication of BOD removals may be obtained by

reference to Appendix E, Figure No. 2. The figure

should not be used to design units which receive

wastewaters which have BOD and total suspended solids

concentrations which are substantially different from

normal domestic sewage. The operating characteristics

of such units should be established by appropriate field

and laboratory tests. If activated sludge is wasted to

the primary settling unit, then the design surface

settling rate shall not exceed 1,000 gallons per day per

square foot based on design peak hourly flow, including

all flows to the unit. Refer to subsection (b)(3) and

Section 370.820.

B) Combined Sewer Overflow and Bypass Settling

The maximum surface settling rate shall not exceed 1,800

gallons per day per square foot based on peak hourly

flow. Minimum liquid depth shall not be less than 10

feet. Minimum detention shall not be less than one

hour. The minimum length of flow from inlet baffle to

outlet should be 10 feet, unless special provisions are

made to prevent short-circuiting.

2) Intermediate Settling Tanks

Surface settling rates for intermediate settling tanks

following series units of fixed film reactor processes should

not exceed 1500 gallons per day per square foot based on

design peak hourly flow. Surface settling rates for

intermediate settling tanks following the activated sludge

process shall not exceed 1000 gallons per day per square foot

based on design peak hourly flow.

3) Final Settling Tanks

Settling tests should be conducted wherever a pilot study of

biological treatment is warranted by unusual waste

characteristics or treatment requirements. Testing shall be

done where proposed loadings go beyond the limits set forth

in subsections (b)(3)(A) and (b)(3)(B).

A) Final Settling Tanks - Fixed Film Biological Reactors

Surface settling rates for settling tanks following

trickling filters or rotating biological contactors

shall not exceed 1000 gallons per day per square foot

based on design peak hourly flow.

B) Final Settling Tanks - Activated Sludge

i) Multiple units capable of independent operation

shall be provided at all plants. To perform

properly while producing a concentrated return

flow, activated sludge settling tanks must be

designed to meet thickening as well as solids

separation requirements.

ii) Since the rate of recirculation of return sludge is

quite high in activated sludge processes, surface

settling rate and weir overflow rate should be

adjusted for the various processes to minimize the

problems with sludge loadings, density currents,

inlet hydraulic turbulence, and occasional poor

sludge settleability.

iii) The hydraulic loadings shall not exceed 1000

gallons per day per square foot based on design

peak hourly flow, and 800 gallons per day per

square foot based on peak hourly flow for separate

activated sludge nitrification stage. Refer to

Section 370.1210(c)(4).

iv) The solids loading shall not exceed 50 pounds

solids per day per square foot at the design peak

hourly rate.

v) Flow equalization is recommended where the peak

hourly load exceeds 300% of the design average

load.

C) Rectangular Units

Rectangular final settling tanks following the activated

sludge process frequently exhibit poor solids separation

characteristics and should therefore be avoided. If

land availability or other local conditions mandate the

use of rectangular final clarifiers following the

activated sludge process, the following design

modifications shall be made:

i) Within practicable limits, length shall be

approximately equal to the width.

ii) Excess weir length shall be provided.

iii) Baffles shall be provided to interrupt

longitudinal density currents.

iv) Weir placement shall be adjustable, so as to allow

optimization of the upflow takeoff points.

c) Inlet Structures

Inlets and inlet baffling should be designed to dissipate the

inlet velocity, to distribute the flow equally both horizontally

and vertically and to prevent short circuiting. Channels should

be designed to maintain a velocity of at least one foot per second

at one-half the design flow. Corner pockets and dead ends should

be eliminated and corner fillets or channeling used where

necessary. Provisions shall be made for prevention or removal of

floating materials in inlet structures.

d) Weirs

1) General

Overflow weirs shall be readily adjustable over the life of

the structure to correct for differential settlement of the

tank.

2) Location

Overflow weirs shall be located to optimize actual hydraulic

detention time, and minimize short circuiting.

3) Design Rates

Weir loadings shall not exceed 20,000 gallons per day per

lineal foot based on design peak hourly flows for plants

having design average flows of 1.0 mgd or less. Overflow

rates shall not exceed 30,000 gallons per day per lineal foot

based on design peak hourly flow for plants having design

average flow of greater than 1.0 mgd. Higher weir overflow

rates may be allowed for bypass settling tanks. If pumping

is required, weir loadings should be related to pump delivery

rates to avoid short circuiting. Refer to Section

370.410(c)(8).

4) Weir Troughs

Weir troughs shall be designed to prevent submergence at

maximum design flow, and to maintain a velocity of at least

one foot per second at one-half design average flow.

e) Submerged Surfaces

The tops of troughs, beams, and similar submerged construction

elements shall have a minimum slope of 1.4 vertical to 1

horizontal; the underside of such elements should have a slope of

1 to 1 to prevent the accumulation of scum and solids.

f) Unit Dewatering

Unit dewatering featuring shall conform to the provisions outlined

in Section 370.530. The bypass design should also provide for

redistribution of the plant flow to the remaining units.

g) Freeboard

Walls of settling tanks shall extend at least 6 inches above the

surrounding ground surface and shall provide not less than 12

inches freeboard. Additional freeboard or the use of wind screens

is recommended where larger settling tanks are subject to high

velocity wind currents that would cause tank surface waves and

inhibit effective scum removal.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Scum Removal

Full surface mechanical scum collection and removal facilities,

including baffling, shall be provided for all settling tanks,

except for Imhoff tanks. The unusual characteristics of scum

which may adversely affect pumping, piping, sludge handling and

disposal, should be recognized in design. Provisions may be made

for the discharge of scum with the sludge; however, other special

provisions for disposal may be necessary. Refer to Section

370.710(g).

b) Sludge Removal

Mechanical sludge collection and withdrawal facilities shall be

designed to assure an effective and controlled rate of removal of

the sludge. Suction withdrawal is encouraged.

1) Sludge Hopper

The minimum slope of the side walls shall be 1.7 vertical to

1 horizontal. Hopper wall surfaces should be made smooth

with rounded corners to aid in sludge removal. Hopper

bottoms shall have a maximum dimension of 2 feet. Extra

depth sludge hoppers for sludge thickening are not

acceptable.

2) Cross-Collectors

Cross-collectors serving one or more settling tanks may be

useful in place of multiple sludge hoppers.

3) Sludge Removal Piping

Each hopper shall have an individually valved sludge

withdrawal line at least 6 inches in diameter. The static

head available for withdrawal of sludge shall be 30 inches or

greater, as necessary to maintain a 3 feet per second

velocity in the withdrawal pipe. Clearance between the end

of the withdrawal line and the hopper walls shall be

sufficient to prevent "bridging" of the sludge. Adequate

provisions shall be made for rodding or back-flushing

individual pipe runs. Piping shall also be provided to

return waste sludge from secondary and tertiary processes to

primary clarifiers where they are used. Refer to Section

370.820.

4) Sludge Removal Control

Sludge wells equipped with telescoping valves or swing pipes

are recommended for primary sludge and fixed film sludges

where periodic withdrawal is proposed. Air lift type of

sludge removal will not be approved for removal of primary

sludges.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Operator Protection

All settling tanks shall be equipped to enhance safety for

operators. Such features shall appropriately include machinery

covers, life lines, stairways, walkways, handrails and

slip-resistant surfaces. If sidewalls are extended more than

three feet above the liquid level or four feet above ground level,

convenient walkways must be provided to facilitate housekeeping

and maintenance.

b) Mechanical Maintenance Access

The design shall provide for convenient and safe access to routine

maintenance items such as gear boxes, scum removal mechanisms,

baffles, weirs, inlet stilling baffle area, and effluent channels.

c) Electrical Fixtures and Controls

Electrical fixtures and controls in enclosed settling basins shall

meet the requirements of the National Electric Code for Class I,

Group D, Division 1 locations. The fixtures and controls shall be

located so as to provide convenient and safe access for operation

and maintenance. Adequate area lighting shall be provided.

a) General

Imhoff tanks may be used for the sedimentation of settleable

solids and for the unheated anaerobic digestion of these solids.

b) Settling Compartment Design

1) Settling Rate

Surface settling rate shall not exceed 1000 gallons per day

per square foot based upon design peak hourly flow.

2) Detention Period

A detention period of not less than 1 hour based upon design

peak hourly flow shall be provided.

3) Dimensions

The minimum length of flow between inlet and outlet should be

10 feet and at least 6 feet of settling depth should be

provided.

4) Freeboard

The freeboard shall be 18 inches or more.

5) Hopper Slope

The bottom of the settling chamber of the conventional tank

shall have a slope of at least 1.4 vertical to 1.0

horizontal. The slot at the bottom of the settling chamber

allowing solids passage shall have a minimum opening and a

minimum overlap of 6 inches.

6) Inlets and Outlets

Inlet and outlet arrangements should be designed so that the

direction of flow may be reversed to allow for a more even

distribution of solids in the digestion compartment.

Adequate scum baffles shall be provided at the ends of the

flow-through chamber.

7) Weirs

Weir design and overflow rates shall be in accordance with

Section 370.710(d).

8) Walkway

A walkway along the length of the tank shall be provided.

c) Sludge Digestion Compartment Design

1) Digestion Chamber Capacity

The digestion chamber shall provide 4 cubic feet of volume

per capita for primary treatment and should provide 6 cubic

feet of volume per capita if secondary process sludge is also

to be digested. The capacity shall be measured below a

horizontal plane 18 inches below the settling chamber slot.

2) Vent Area

A surface area equal to 20% of the total tank surface area

shall be provided for venting the digestion compartment.

3) Hopper Slope

The bottom of the digestion chamber should be a hopper type

structure with minimum side slopes of 1.75 vertical to 1.0

horizontal. Sludge draw-off from the digestion chamber is

usually accomplished by utilizing the hydrostatic head with a

minimum differential of 6 feet being required. Eight inch

diameter sludge draw-off piping or larger shall be used.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) General

Septic tank tile systems shall be used only for domestic or

similar organic waste, where soil conditions are suitable and

sewers tributary to treatment works are not available.

b) Design Standards

Specific design information is contained in the document titled

"Private Sewage Disposal Licensing Act & Code", which can be

obtained from:

State of Illinois

Department of Public Health

Springfield, Illinois 62706.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

SUBPART H: SLUDGE PROCESSING AND DISPOSAL

Facilities for processing sludge shall be provided at all mechanical sewage

treatment plants. Handling equipment shall be capable of processing sludge

to a form suitable for ultimate disposal.

The selection of sludge handling unit processes should be based upon at

least the following considerations:

a) Local land use.

b) System energy requirements.

c) Cost effectiveness of sludge thickening and dewatering.

d) Equipment complexity and staffing requirements.

e) Adverse effects of heavy metals and other sludge components upon

the unit processes.

f) Sludge digestion or stabilization requirements.

g) Side stream or return flow treatment requirements (e.g., digester

or sludge storage facilities supernatant, dewatering unit

filtrate, wet oxidation return flows).

h) Sludge storage requirements.

i) Methods of ultimate disposal.

j) Back-up techniques of sludge handling and disposal.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Sludge thickeners to reduce the volume of sludge should be

considered. The design of thickeners (gravity tank, gravity

belt, dissolved-air flotation, centrifuge, and others) should take

into account the type and concentration of sludge, the sludge

stabilization processes, storage requirements, the method of

ultimate sludge disposal, chemical needs, and the cost of

operation. The use of gravity thickening tanks for unstabilized

sludges is not recommended because of problems due to septicity

unless provisions are made for adequate control of process

operational problems as well as problems of odors at the gravity

thickener and any following unit processes. Particular attention

should be given to the pumping and piping of the concentrated

sludge and possible onset of anaerobic conditions.

b) Process selection and unit process design parameters should be

based on prototype studies. The Agency will require such studies

where the sizing of other plant units is dependent on performance

of the thickeners. Refer to Section 370.520(b) for any new

process determination.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) General

1) Multiple Units

Multiple units or alternate methods of sludge processing

shall be provided. Facilities for sludge storage and

supernatant separation in an additional unit may be required,

depending on raw sludge concentration and disposal methods

for sludge and supernatant.

2) Depth

If process design provides for supernatant withdrawal, the

proportion of depth to diameter should be such as to allow

for the formation of a reasonable depth of supernatant

liquor. A minimum side water depth of 20 feet is

recommended.

3) Design Maintenance Provisions

To facilitate emptying, cleaning, and maintenance the

following features are desirable:

A) Slope

The tank bottom shall slope to drain toward the

withdrawal pipe. For tanks equipped with a suction

mechanism for sludge withdrawal, a bottom slope not less

than 1 to 12 is recommended. Where the sludge is to be

removed by gravity alone, 1 to 4 slope is recommended.

B) Access Manholes

At least 2 access manholes should be provided in the top

of the tank in addition to the gas dome. There should

be stairways to reach the access manholes. A separate

side wall manhole shall be provided that is large enough

to permit the use of mechanical equipment to remove grit

and sand. The side wall access manhole should be low

enough to facilitate heavy equipment handling and may be

buried in the earthen bank insulation.

C) Safety

Non-sparking tools, rubber-soled shoes, safety harness,

gas detectors for inflammable and toxic gases, and at

least two self-contained breathing units shall be

provided for emergency use.

4) Toxic Materials

If the anaerobic digestion process is proposed, the basis of

design shall be supported by wastewater analyses to determine

the presence of undesirable materials, such as high

concentrations of sulfates and inhibitory concentrations of

heavy metals.

b) Sludge Inlets and Outlets, Recirculation and High Level Overflows

1) Multiple sludge inlets and draw-offs and, where used,

multiple recirculation suction and discharge points to

facilitate flexible operation and effective mixing of the

digester contents shall be provided unless adequate mixing

facilities are provided within the digester.

2) One inlet should discharge above the liquid level and be

located at approximately the center of the tank to assist in

scum breakup. The second inlet should be opposite to the

suction line at approximately the 2/3 diameter point across

the digester.

3) Raw sludge inlet discharge points should be so located as to

minimize short circuiting to the digested sludge or

supernatant draw-offs.

4) Sludge withdrawal to disposal should be from the bottom of

the tank. The bottom withdrawal pipe should be

interconnected with the necessary valving to the

recirculation pipe, to increase versatility in mixing the

tank contents.

5) An unvalved vented overflow shall be provided to prevent

damage to the digestion tank and cover in case of accidental

overfilling. This emergency overflow shall be piped to a

point and at a rate in the treatment process or sidestream

treatment facilities so as to minimize the impact on process

units.

c) Tank Capacity

1) Rational Design

The total digestion tank capacity shall be determined by

rational calculations based upon such factors as volume of

sludge added, its percent solids, and character, the

temperature to be maintained in the digesters, the degree or

extent of mixing to be obtained, the degree of volatile

solids reduction required, method of sludge disposal, and the

size of the installation with appropriate allowances for gas,

scum, supernatant and digested sludge storage. Secondary

digesters of two-stage series digestion systems that are used

for digested sludge storage and concentration shall not be

credited in the calculations for volumes required for sludge

digestion. Calculations should be submitted to justify the

basis of design.

2) Empirical Design

When such calculations are not submitted to justify the

design based on the above factors, the minimum combined

digestion tank capacity outlined below will be required.

Such requirements assume that the raw sludge is derived from

ordinary domestic wastewater, a digestion temperature is to

be maintained in the range of 85 to 95 F (29 to 35 C), 40

to 50 percent volatile matter in the digested sludge, and

that the digested sludge will be removed frequently from the

process. (See also subsection (a)(1) above and Section

370.860(a)(1).)

A) Completely Mixed Systems

For digestion systems providing for intimate and

effective mixing of the digester contents, the system

may be loaded up to 80 pounds of volatile solids per

1000 cubic feet of volume per day in the active

digestion units.

B) Moderately Mixed Systems

For digestion systems where mixing is accomplished only

by circulating sludge through an external heat

exchanger, the system may be loaded up to 40 pounds of

volatile solids per 1000 cubic feet of volume per day in

the active digestion units. This loading may be

modified upward or downward depending upon the degree of

mixing provided.

C) Digester Mixing

Facilities for mixing the digester contents shall be

provided where required for proper digestion by reason

of loading rates or other features of the system. Where

sludge recirculation pumps are used for mixing, they

shall be provided in accordance with the applicable

requirements of Section 370.850(a).

d) Gas Collection, Piping, and Appurtenances

1) General

All portions of the gas system including the space above the

tank liquor, storage facilities and piping shall be so

designed that under all normal operating conditions,

including sludge withdrawal, the gas will be maintained under

pressure. All enclosed areas where any gas leakage might

occur shall be adequately ventilated.

2) Safety Equipment

All necessary safety facilities shall be included where gas

is produced. Pressure and vacuum relief valves and flame

traps together with automatic safety shut off valves shall be

provided and protected from freezing. Water seal equipment

shall not be installed. Safety equipment and gas compressors

should be housed in a separate room with an exterior door.

3) Gas Piping and Condensate

Gas piping shall have a minimum diameter of 4 inches, except

that a smaller diameter pipe may be used at the gas

production meter. Gas piping shall slope to condensation

traps at low points. The use of float-controlled condensate

traps is not permitted. Condensation traps shall be

protected from freezing. Tightly fitted self-closing doors

should be provided at connecting passageways and tunnels

which connect digestion facilities to other facilities to

minimize the spread of gas. Piping galleries shall be

ventilated in accordance with subsection (d)(7).

4) Gas Utilization Equipment

Gas burning boilers, engines, etc., shall be located in well

ventilated rooms. Such rooms would not ordinarily be

classified as a hazardous location if isolated from the

digestion gallery or ventilated in accordance with subsection

(d)(7). Gas lines to these units shall be provided with

suitable flame traps.

5) Electrical Fixtures

Electrical fixtures and controls, in places enclosing

anaerobic digestion appurtenances, where hazardous gases are

normally contained in the tanks and piping, shall comply with

the National Electric Code for Class 1, Group D, Division 2

locations. Refer to subsection (d)(7).

6) Waste Gas

A) Waste gas burners shall be readily accessible and should

be located at least 50 feet away from any plant

structure if placed at ground level, or may be located

on the roof of the control building if sufficiently

removed from the tank. Waste gas burners shall be of

sufficient height to prevent injury to personnel due to

wind or downdraft conditions.

B) All waste gas burners shall be equipped with automatic

ignition such as a pilot light or a device using a

photoelectric cell sensor. Consideration should be

given to the use of natural or propane gas to insure

reliability of the pilot.

C) Gas piping shall be sloped at a minimum of 2 percent up

to the waste gas burner with a condensate trap provided

in a location not subject to freezing.

7) Ventilation

Any underground enclosures connecting with digestion tanks or

containing sludge or gas piping or equipment shall be

provided with forced ventilation in accordance with Section

370.410(g)(1-4) and (6).

8) Meter

A gas meter with bypass shall be provided to meter total gas

production for each active digestion unit. Total gas

production for two-stage digestion systems operated in series

may be measured by a single gas meter with proper

interconnected gas piping. Where multiple primary digestion

units are used with a single secondary digestion unit, a gas

meter shall be provided for each primary digestion unit. The

secondary digestion unit may be interconnected with the gas

measurement unit of one of the primary units. Interconnected

gas piping shall be properly valved with gastight gate valves

to allow measurement of gas production from, or maintenance

of, either digestion unit. Gas meters may be of the orifice

plate, turbine or vortex type. Positive displacement meters

are not recommended. The meter used must be specifically

designed for contact with corrosive and dirty gases.

e) Digestion Tank Heating

1) Insulation

Wherever possible digestion tanks should be constructed above

ground-water level and shall be suitably insulated to

minimize heat loss. Maximum utilization of earthen bank

insulation should be used.

2) Heating Facilities

Sludge may be heated by circulating the sludge through

external heaters or by units located inside the digestion

tank. Refer to subsection (e)(2)(B).

A) External Heating

Piping shall be designed to provide for the preheating

of feed sludge before introduction into the digesters.

Provisions shall be made in the lay-out of the piping

and valving to facilitate heater exchanger tube removal

and cleaning of the lines. Heat exchanger sludge piping

should be sized for peak heat transfer requirements.

Heat exchangers should have a heating capacity of 130

percent of the calculated peak heating requirement to

account for sludge tube fouling.

B) Other Heating Methods

i) The use of hot water heating coils affixed to the

walls of the digester, or other types of internal

heating equipment that require emptying the

digester contents for repair, are not acceptable.

ii) Other systems and devices have been developed

recently to provide both mixing and heating of

anaerobic digester contents. These systems will be

reviewed on their own merits. Operating data

detailing their reliability, operation and

maintenance characteristics will be required.

3) Heating Capacity

A) Sufficient heating capacity shall be provided to

consistently maintain the design sludge temperature

considering the insulation provided and ambient cold

weather conditions. Where digestion tank gas is used

for other purposes, an auxiliary fuel may be required.

B) The provision of standby heating capacity or the use of

multiple units sized to provide the heating requirements

shall be considered unless acceptable alternative means

of handling raw sludge are provided.

4) Hot Water Internal Heating Controls

A) Mixing Valves

A suitable automatic mixing valve shall be provided to

temper the boiler water with return water so that the

inlet water to the removable heat jacket or coil in the

digester can be held below a temperature at which caking

will be accentuated. Manual control should also be

provided by suitable bypass valves.

B) Boiler Controls

The boiler should be provided with suitable automatic

controls to maintain the boiler temperature at

approximately 180 F (82 C) to minimize corrosion and

to shut off the main gas supply in the event of pilot

burner or electrical failure, low boiler water level,

low gas pressure, excessive boiler water temperature or

pressure.

C) Boiler Water Pumps

Boiler water pumps shall be sealed and sized to meet the

operating conditions of temperature, operating head and

flow rate. Duplicate units shall be provided.

D) Thermometers

Thermometers shall be provided to show inlet and outlet

temperatures of the sludge, hot water feed, hot water

return and boiler water.

E) Water Supply

The chemical quality of the water supply shall be

suitable for use as boiler water. Refer to Section

370.550(b) for additional water supply considerations.

5) External Heater Operating Controls

All controls necessary to insure effective and safe operation

are required. Provision for duplicate units in critical

elements should be considered.

f) Supernatant Withdrawal

Where supernatant separation is to be used to concentrate sludge

in the digester units and increase digester solids retention time,

the design shall provide for ease of operation and positive

control of supernatant quality.

1) Piping Size

Supernatant piping should not be less than 6 inches in

diameter.

2) Withdrawal Arrangements

A) Withdrawal Levels

Piping should be arranged so that withdrawal can be made

from 3 or more levels in the tank. An unvalved vented

overflow shall be provided. The emergency overflow

shall be piped to a point and at a rate in the treatment

process or sidestream treatment facilities so as to

minimize the impact on process units.

B) Withdrawal Selection

On fixed cover tanks the supernatant withdrawal level

should preferably be selected by means of

interchangeable extensions at the discharge end of the

piping.

C) Supernatant Selector

A fixed screen supernatant selector or similar device

may only be used in an unmixed secondary digestion unit.

If such a supernatant selector is provided, provisions

shall be made for at least one other draw-off level

located in the supernatant zone of the tank, in addition

to the unvalved emergency supernatant draw-off pipe.

High pressure back-wash facilities shall be provided.

3) Sampling

Provision shall be made for sampling at each supernatant

draw-off level. Sampling pipes should be at least 1 1/2

inches in diameter and should terminate at a suitably sized

sampling sink or basin.

4) Supernatant Disposal

Supernatant return and disposal facilities shall be designed

to prevent adverse hydraulic and organic effects on plant

operations. If nutrient removal (e.g., phosphorus, ammonia)

must be accomplished at a plant, then a separate supernatant

side stream treatment system should be considered.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) General

The aerobic sludge digestion system shall include provisions for

digestion, supernatant separation, sludge concentration and any

necessary sludge storage. These may be accomplished with separate

tanks or processes or in digestion tanks.

b) Multiple Units

Multiple digestion units capable of independent operation are

recommended for all plants and shall be provided in those plants

where the design average flow exceeds 100,000 gallons per day.

Plants without multiple units shall provide alternate sludge

handling and disposal methods.

c) Tank Capacity

1) The following digestion tank capacities are based on a solids

concentration of 2 percent with supernatant separation

performed in a separate tank. If supernatant separation is

performed in the digestion tank, a minimum of 25 percent

additional volume is required. These capacities shall be

provided unless sludge thickening facilities (refer to

Section 370.820) are utilized to thicken the feed solids

concentration to greater than 2 percent. If such. thickening

is provided, the digestion volumes may be decreased

proportionally.

Volume (ft.(3)/Population

Waste activated sludge-no

primary settling 4.5*

Primary plus waste activated

sludge 4.0*

Waste activated sludge

exclusive of primary sludge 2.0*

Extended aeration activated

sludge 3.0

Primary plus fixed film

reactor sludges 3.0

*These volumes apply to waste activated sludge from single stage

nitrification facilities with less than 24 hours detention time

based on design average flow.

2) These volumes are based on digester temperatures of 59 F

(15 C) and a solids retention time of 27 days. Aerobic

digesters shall be covered to minimize heat loss or these

volumes shall be increased for colder temperature

applications. Refer to subsection (g) below for necessary

sludge storage. Additional volume may be required if the

land application disposal method is used in order to meet

applicable Federal regulations.

d) Mixing

Aerobic digesters shall be equipped with devices which can

maintain solids in suspension and which provide complete mixing of

the digester contents.

e) Air Requirements

Sufficient air shall be provided to keep the solids in suspension

and maintain dissolved oxygen between 1 and 2 milligrams per liter

(mg/l). For minimum mixing and oxygen requirements, an air supply

of 30 cfm per 1000 cubic feet of tank volume shall be provided

with the largest blower out of service. If diffusers are used,

the nonclog type is recommended, and they should be designed to

permit continuity of service. If mechanical turbine aerators are

utilized, at least two turbine aerators per tank shall be provided

to permit continuity of service. Mechanical aerators are not

acceptable for use in aerobic digesters due to freezing

conditions experienced throughout Illinois.

f) Supernatant Separation and Scum and Grease Removal

1) Supernatant Separation

Facilities shall be provided for effective separation or

decanting of supernatant. Separate facilities are

recommended; however, supernatant separation may be

accomplished in the digestion tank if additional volume is

provided, in accordance with subsection (c) above. The

supernatant drawoff unit shall be designed to prevent the

recycle of scum and grease back to plant process units.

Provision should be made to withdraw supernatant from

multiple levels of the supernatant withdrawl zone.

2) Scum and Grease Removal

Facilities shall be provided for the effective collection of

scum and grease for final disposal and to prevent recycle

back to plant process units and prevent long term

accumulation and potential for discharge of scum and grease

in the effluent.

g) High Level Emergency Overflow

An unvalved high level overflow and any necessary piping shall be

provided to return digester overflow back to the head of the plant

or to the aeration process in case of accidental overfilling. The

design of the overflow shall take into account the length of time

and rate at which sludge is wasted during periods when the

treatment plant is unattended, potential effects of overflow on

plant process units, location of the discharge from the emergency

overflow, and the potential for discharge of suspended solids in

the plant effluent.

h) Digested Sludge Storage Volume

1) Sludge storage must be provided in accordance with Section

370.870 to accommodate daily sludge production volumes and

as an operational buffer for unit outage and adverse weather

conditions. Designs utilizing increased sludge age in the

activated sludge system as a means of storage are not

acceptable.

2) Liquid sludge storage capacity shall be based on the

following values unless digested sludge thickening facilities

are utilized (refer to Section 370.173) to provide solids

concentrations to greater than 2 percent.

Waste activated sludge-no

primary settling, primary

plus waste activated sludge,

and extended aeration

activated sludge 0.13

Waste activated sludge

exclusive of primary sludge 0.06

Primary plus fixed film

reactor sludged 0.10

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) General

Alkaline material may be added to liquid primary or secondary

sludges for sludge stabilization in lieu of digestion facilities,

to supplement existing digestion facilities, or for interim sludge

handling. Inasmuch as the high pH stabilization process does not

reduce organic matter but rather increases the mass of dry sludge

solids, so that additional volumes of sludge will be generated in

the absence of supplemental dewatering, the design shall account

for the increased sludge quantities for storage and handling,

transportation and disposal methods and associated costs.

Alkaline material may be added to dewatered sludges for

stabilization pursuant to Section 370.520(b).

b) Operational Criteria

Sufficient alkaline material shall be added to liquid sludge in

order to produce a homogeneous mixture with a minimum pH of 12

after 2 hours of vigorous mixing. Facilities for adding

supplemental alkaline material shall be provided to maintain the

pH of the sludge during interim sludge storage periods.

c) Odor Control and Ventilation

Odor control facilities shall be provided for sludge mixing and

treated sludge storage tanks that are located within 1/2 mile of

residential or commercial areas. Indoor sludge mixing, storage

and processing facilities shall have ventilation that meets the

ventilation requirements contained in Section 370.410(g)(1-4) and

(6) and shall comply with the safety precautions contained in

Section 370.560. Adequate facilities shall be provided to

condition the exhaust air to meet the applicable substantive and

permitting requirements of 35 Ill. Adm. Code Subtitle B: Air

Pollution.

d) Mixing Tanks and Equipment

1) Tanks

Mixing tanks may be designed to operate as either a batch or

continuous flow process. A minimum of two tanks of adequate

size to provide a minimum of 2 hours of contact time in each

tank shall be provided. The following factors shall also be

taken into account in determining the number and size of

tanks:

A) Peak sludge flow rates;

B) Storage between batches;

C) Dewatering or thickening performed in tanks;

D) Repeating sludge treatment due to pH decay of stored

sludge;

E) Sludge thickening prior to sludge treatment;

F) Type of mixing device used and associated maintenance

and repair requirements.

2) Equipment

Mixing equipment shall be designed to provide vigorous

agitation within the mixing tank, to maintain solids in

suspension and to provide for a homogenous mixture of the

sludge solids and alkaline material. Mixing may be

accomplished by either diffused aeration or mechanical

mixing. For diffused aeration, an air supply of 30 cfm per

1000 cubic feet of mixing tank volume with the largest blower

out of service shall be provided. Nonclogging diffusers

designed to permit continuity of service should be used.

Mechanical mixers shall be designed to assure continuity of

service during freezing weather conditions and shall be

equipped with impellers designed to minimize fouling from

debris in the sludge.

e) Chemical Feed and Storage Equipment

1) General

Equipment used for handling or storing alkaline shall be

designed to provide operator protection from eye and tissue

damage. Refer to Section 370.560 for proper safety

precautions. Material storage, slaking and feed equipment

shall be sealed as airtight as practicable to prevent contact

of alkaline material with atmospheric carbon dioxide and

water vapor and to prevent the escape of dust material. All

equipment and associated transfer lines and piping shall be

accessible for cleaning.

2) Feed and Slaking Equipment

The design of the feeding equipment shall be determined by

the treatment plant size, type of alkaline material used,

slaking required and operator requirements. Automated or

batch equipment may be used. Automated feeders may be

volumetric or gravimetric, based on accuracy, reliability and

maintenance requirements. Manually operated batch slaking of

quicklime (CaO) should be avoided unless protective clothing

and equipment are provided. At small plants, for safety

reasons the use of hydrated lime (Ca(OH)[2]) over quicklime

is recommended. Feed and slaking equipment shall be sized to

handle a minimum of 150% of the peak sludge flow rate,

including sludge that may need to be retreated due to pH

decay. Duplicate units shall be provided.

3) Chemical Storage Facilities

Alkaline materials may be received in either bag or bulk

form. Materials delivered in bags must be stored indoors and

elevated above floor level. Bags should be multi-walled and

moisture-proof. Dry bulk storage containers must be as

airtight as practicable and shall contain a mechanical

agitation mechanism. Storage facilities shall be sized to

provide a minimum 30-day supply of alkaline materials.

Adequate provisions shall be made to meet the applicable

substantive and permitting requirements of 35 Ill. Adm. Code

Subtitle B: Air Pollution.

f) Sludge Storage

Refer to Section 370.870 for general design considerations for

sludge storage facilities. The design shall incorporate the

following considerations for the storage of high pH stabilized

sludge:

1) Liquid Sludge

Liquid high pH stabilized sludge shall be stored in a tank or

vessel equipped with rapid sludge withdrawl mechanisms for

sludge disposal or retreatment and may not be stored in a

lagoon. Provision shall be made for adding alkaline material

in the storage tank. Mixing equipment meeting the

requirements of subsection (d)(2) above shall be provided in

all storage tanks.

2) Dewatered Sludge

On-site storage of dewatered high pH stabilized sludge shall

be limited to 30 days. Provisions shall be made for rapid

retreatment or disposal of dewatered sludge stored on site in

case of sludge pH decay.

3) Off-Site Storage

There shall be no off-site storage of high pH stabilized

sludge unless the Agency has issued a permit for off-site

storage.

g) Disposal

Methods and options for immediate sludge disposal should be used

in order to reduce the on-site sludge inventory and the amount of

sludge that must be retreated to reduce odors when sludge pH decay

occurs. Where land application is used, the sludge must be

incorporated into the soil within 24 hours after application.

(Source: Added at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Sludge Pumps

1) Capacity

Pump capacities shall be adequate but not excessive.

Provision for varying pump capacity is desirable. A rational

basis of design shall be provided with the plan documents.

2) Duplicate Units

Duplicate units shall be provided at all installations.

3) Type

Plunger pumps, screw feed pumps or other types of pumps with

demonstrated solids handling capability shall be provided for

handling raw sludge. Where centrifugal pumps are used, a

parallel positive displacement pump shall be provided as an

alternate to pump heavy sludge concentrations, such as

primary or thickened sludges, that may exceed the pumping

head of the centrifugal pump.

4) Minimum Head

A minimum positive head of 24 inches shall be provided at the

suction side of centrifugal type pumps and is desirable for

all types of sludge pumps. Maximum suction lifts should not

exceed 10 feet for plunger pumps.

5) Sampling Facilities

Unless sludge sampling facilities are otherwise provided,

quick closing sampling valves shall be installed at the

sludge pumps. The size of valve and piping should be at

least 1 1/2 inches and terminate at a suitably sized sampling

sink or floor drain.

b) Sludge Piping

1) Size and Head

Digested sludge withdrawal piping should have a minimum

diameter of 8 inches for gravity withdrawal and 6 inches for

pump suction and discharge lines. Where withdrawal is by

gravity, the available head on the discharge pipe should be

at least 4 feet and preferably more. Undigested sludge

withdrawl piping shall be sized in accordance with Section

370.720(b)(3).

2) Slope and Flushing Requirements

Gravity piping should be laid on uniform grade and alignment.

Slope on gravity discharge piping should not be less than 3

percent for primary sludges and all sludges thickened to

greater than 2 percent solids. The slope on gravity

discharge piping should not be less than 2 percent for

aerobicly digested sludge or waste activated sludge with less

than 2 percent solids. Cleanouts shall be provided for all

gravity sludge piping. Provisions shall be made for draining

and flushing discharge lines. All sludge pipe shall be

suitably located or otherwise adequately protected to prevent

freezing.

3) Supports

Special consideration shall be given to the corrosion

resistance and permanence of supporting systems for piping

located inside the digestion tank.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) General

On-site sludge dewatering facilities shall be provided for all

plants, although the following requirements may be reduced or

omitted, if justified, with on-site liquid sludge storage

facilities or approved off-site sludge disposal.

1) Anaerobic Digestion Sludge Production

For purposes of calculating sludge handling and disposal

needs, sludge production values from a two-stage anaerobic

digestion process shall be based on a maximum solids

concentration of 5% without additional thickening. The

solids production values, calculated on a dry weight basis,

shall be based on the following values for the listed

processes:

A) Primary plus waste activated sludge--at least 0.12

lbs/P.E./day;

B) Primary plus fixed film reactor sludge--at least 0.09

lbs/P.E./day.

2) Aerobic Digestion Sludge Production

For purposes of calculating sludge handling and disposal

needs, sludge production values from an aerobic digester

shall be based on a maximum solids concentration of 2%

without additional thickening. The solids production

values, calculated on a dry weight basis, shall be based on

the following values for the listed processes:

A) Primary plus waste activated sludge--at least 0.16

lbs/P.E./day;

B) Primary plus fixed film reactor sludge--at least 0.12

lbs/P.E./day.

3) Production from Other Sludge Treatment Processes

For purposes of calculating sludge handling and disposal

needs, sludge production values from other sludge treatment

processes shall be determined by rational calculations in the

basis of design. Refer to Section 370.520(b) for any new

process determinations.

b) Sludge Drying Beds

1) Applicability

Sludge drying beds may be used for dewatering well digested

sludge from either the anaerobic or aerobic process. Due to

the large volume of sludge produced by the aerobic digestion

process, consideration should be given to using a combination

of dewatering systems or other means of ultimate sludge

disposal.

2) Unit Sizing

Sludge drying bed area shall be calculated on a rational

basis with the following items taken into account:

A) The volume of wet sludge produced by existing and

proposed processes.

B) Depth of wet sludge drawn to the drying beds. For

design calculations purposes a maximum depth of 8 inches

shall be utilized. For operational purposes, the depth

of sludge placed on the drying bed may vary from the

design depth based on the solids content and the type of

digestion used.

C) Total digester volume and other wet sludge storage

facilities.

D) Degree of sludge thickening provided after digestion.

E) The maximum drawing depth of sludge which can be removed

from the digester or other sludge storage facilities

without causing process or structural problems.

F) The time required on the bed to produce a removable

cake. Adequate provision shall be made for sludge

dewatering and/or sludge disposal facilities for those

periods of time during which outside drying of sludge on

beds is hindered by weather. For Illinois that season

is considered to extend from early November through at

least April.

G) Capacities of auxiliary dewatering facilities.

3) Percolation Type Bed Components

A) Gravel

The lower course of gravel around the underdrains should

be properly graded and should be 12 inches in depth,

extending at least 6 inches above the top of the

underdrains. It is desirable to place this in 2 or more

layers. The top layer of at least 3 inches should

consist of gravel 1/8 inch to 1/4 inch in size.

B) Sand

The top course should consist of at least 6 to 9 inches

of clean, washed, coarse sand. The effective size of

the sand should be in the range of 0.8 to 1.5

millimeters. The finished sand surface should be level.

C) Underdrains

Underdrains should be at least 4 inches in diameter laid

with open joints. Perforated pipe may also be used.

Underdrains should be spaced not more than 20 feet

apart. Various pipe materials may be used, so long as

they are sufficiently strong and are corrosion

resistant.

D) Additional Dewatering Provisions

Consideration shall be given to providing a means of

decanting the supernatant of sludge placed on the sludge

drying beds. More effective decanting of supernatant

may be accomplished with polymer treatment of the

sludge.

4) Walls

Walls should be water-tight and extend 18 inches above and at

least 6 inches below the surface of the bed. Outer walls

should be curbed or extended at least 4 inches above the

outside grade elevation to prevent soil from washing on to

the beds.

5) Sludge Removal

Each bed shall be constructed so as to be readily and

completely accessible to mechanical cleaning equipment.

Concrete runways spaced to accommodate mechanical equipment

shall be provided. Special attention should be given to

assure adequate access to the areas adjacent to the

sidewalls. Entrance ramps down to the level of the sand bed

shall be provided. These ramps shall be high enough to

eliminate the need for an entrance end wall for the sludge

bed.

c) Sludge Lagoons for Dewatering

1) General

Lagoons as a means of dewatering digested sludge will be

permitted only upon proof that the character of the digested

sludge and the design mode of operation are such that

offensive odors will not result. Where sludge lagoons are

permitted, adequate provisions shall be made for other sludge

dewatering facilities or sludge disposal in the event of

upset or failure of the sludge digestion process.

2) Location

Sludge lagoons shall be located as far as practicable from

inhabited areas or areas likely to be inhabited during the

lifetime of the structures.

3) Seal

Adequate provisions shall be made to seal the lagoon bottoms

and embankments to prevent leaching into adjacent soils or

groundwater. Refer to Section 370.930(d)(1)(A), (d)(2)(C)

and (d)(2)(D).

4) Access

Provisions shall be made for sludge pumping or heavy

equipment access for sludge removal from the lagoon.

d) Mechanical Dewatering Facilities

1) General

Provision shall be made to maintain sufficient continuity of

service so that sludge may be dewatered without accumulation

beyond storage capacity. The number of vacuum filters,

centrifuges, filter presses, belt filters, or other

mechanical dewatering facilities should be sufficient to

dewater the sludge produced with the largest unit out of

service. Unless other standby wet sludge facilities are

available, adequate storage facilities of at least 4 days

production volume shall be provided. Documentation must be

submitted justifying the basis of design of mechanical

dewatering facilities.

2) Water Supply Protection

The water supply for mechanical dewatering facilities shall

meet the requirements of Section 370.550(b).

3) Auxiliary Facilities for Vacuum Filters

Back-up vacuum and filtrate pumps shall be provided. It is

permissible to have uninstalled back-up vacuum and filtrate

pumps for every three or less vacuum filters, provided that

the installed units can easily be removed and replaced. At

least one filter media replacement unit shall be provided.

4) Ventilation

Adequate facilities shall be provided for ventilation of the

dewatering area. The exhaust air should be properly

conditioned to avoid odor nuisance. Ventilation shall be

provided in accordance with Section 370.410(g)(6).

5) Chemical Handling Enclosures

Lime-mixing facilities should be completely enclosed to

prevent the escape of lime dust. Chemical handling equipment

should be automated to eliminate the manual lifting

requirement. Refer to Section 370.560.

e) Drainage and Filtrate Disposal

Drainage from beds or filtrate dewatering units shall be returned

to the sewage treatment process at appropriate points and rates.

f) Other Dewatering Facilities

If it is proposed to dewater sludge by other methods, a detailed

description of the process and design data shall accompany the

plans. Refer to Section 370.520(b) for any new process

determinations.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Storage

1) General

Sludge storage facilities shall be provided at all mechanical

treatment plants, and may consist of any combination of

drying beds, lagoons, separate tanks, additional volume in

stabilization units, pad areas or other means to store either

liquid or dried sludge. Drainage of supernatant from sludge

storage facilities shall be returned to the sewage treatment

process at appropriate points and rates. Refer to Section

370.860(b) and (c) for drying bed and lagoon design criteria,

respectively.

2) Volume

Rational calculations justifying the number of days of

storage based on the total sludge handling and disposal

system shall be submitted. Refer to Sections 370.840(g) and

370.860(a) for anaerobicly and aerobicly digested sludge

production values; values for other stabilization processes

shall be justified on the basis of design. If land

application is the only means of sludge disposal used at a

treatment plant, a minimum of 150 days storage shall be

provided, in order to account for inclement weather and

cropping practices.

b) Disposal

1) Landfilling

Sludge and sludge residues may be disposed of in Agency

approved municipal solid waste landfill units under the terms

and conditions of permits issued by the Agency's Bureau of

Land. On-site landfilling shall be conducted in conformance

with the design recommendations of the Bureau of Land and

must be approved by the Agency's Bureau of Water.

2) Land Application

Specific design criteria for land application of sludge are

set out in Design Criteria for Sludge Application on Land, 35

Ill. Adm. Code 391. Additional operating criteria may be

obtained from applicable Federal regulations. In order to

assure compliance with the facility's effluent standards,

alternative sludge disposal options to account for inclement

weather and cropping practices are recommended.

3) Sludge Lagoons

The use of lagoons for ultimate disposal of sludge is not

recommended because of odor potential, area and volume

required and possible long term problems from groundwater

contamination. If a lagoon is proposed, a hydrogeologic

survey must be performed to demonstrate the appropriateness

of a disposal lagoon at the particular site. A groundwater

monitoring program must be included in any sludge lagoon

design. Refer to Section 370.860(c) for lagoon design

criteria.

4) Other Disposal Methods

A detailed description of the technique and design data shall

accompany the plans of any proposal to dispose of sludge by

methods other than those specified in this Section. Refer to

Section 370.520(b) for any new process determinations.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

SUBPART I: BIOLOGICAL TREATMENT

a) General

1) Applicability

Trickling filters may be used for treatment of sewage

amenable to treatment by aerobic biologic processes.

Trickling filters shall be preceded by settling tanks

equipped with scum and grease collecting devices, or other

suitable pretreatment facilities.

2) Design Basis

Filters shall be designed so as to provide the required

reduction in biochemical oxygen demand, ammonia nitrogen, or

to properly condition the sewage for subsequent treatment

processes.

3) Multiple Units

Multiple trickling filter units capable of independent

operation are recommended for all plants and must be provided

for those plants where the design average flow exceeds

100,000 gallons per day. Plants not having multiple units

shall include other provisions to assure continuity of

treatment.

b) Dosing Equipment

1) Distribution

A) All hydraulic factors involving proper distribution of

sewage on the filter should be carefully calculated and

submitted with the basis of design.

B) The sewage may be distributed over the filter by rotary

distributors or other suitable devices which will permit

reasonably uniform distribution to the surface area. At

design average flow, the deviation from calculated

uniformly distributed volume per square foot of the

filter surface shall not exceed plus or minus 10

percent at any point.

2) Dosing and Recirculation

A) Sewage may be applied to the filters by siphons, pumps

or by gravity discharge from preceding treatment units

when suitable flow characteristics have been developed.

Application of the sewage should be continuous except

for low rate filters. A hydraulic system for

recirculation shall be provided for new facilities and

should be considered where existing trickling filter

units are included in treatment plant upgrading.

B) The piping system, including dosing equipment and

distributor, shall be designed to provide capacity for

the peak hourly flow rate including recirculation rates

determined under subsection (h).

3) Distributor Head Requirements

For reaction type distributors, a minimum head of 24 inches

between low water level in siphon chamber and center of arms

is required. Similar allowances shall be made in design for

added pumping head requirements where pumping to the reaction

type distributor is used. The design shall include the head

required at the center column for the full range of flows,

taking into account all head losses from the center column

back to the dosing facility at all water levels.

Calculations shall be submitted to justify the basis of

design.

4) Clearance

A minimum clearance of 6 inches between media and distributor

arms shall be provided. Refer to subsection (e)(4).

c) Media

1) Quality

The media may be crushed rock, slag or specially manufactured

material. The media shall be durable, resistant to spalling

or flaking, and be relatively insoluble in sewage. The top

18 inches shall have a loss by the 20-cycle, sodium sulfate

soundness test of not more than 10 percent, as prescribed by

ASCE Manual of Engineering Practice, Number 13, the balance

to pass a 10-cycle test using the same criteria. Slag media

shall be free from iron. Manufactured media shall be

resistant to ultraviolet degradation, disintegration,

erosion, aging, all common acid and alkalies, organic

compounds, and fungus and other biological attack. Such

media shall be structurally capable of supporting a man's

weight or a suitable access walkway shall be provided to

allow for distributor maintenance.

2) Depth

The filter media shall have a minimum depth of 6 feet above

the underdrains. For rock media filters (subsection

(c)(3)(A)), only the top 7 feet of the volume of the filter

shall be considered in BOD removal credit computations. For

manufactured media filters see subsection (c)(3)(B).

3) Size and Grading of Media

A) Rock, Slag and Similar Media

i) Rock, slag and similar media shall not contain more

than 5 percent by weight of pieces whose longest

dimension is 3 times the least dimension.

ii) Media shall be free from thin elongated and flat

pieces, dust, clay, sand, or fine material and

shall conform to the following size and grading

when mechanically graded over vibrating screen with

square openings:

Passing 4 1/2 inch screen - 100% by weight

Retained on 3 inch screen - 95-100% by weight

Passing 2 inch screen - 0-2% by weight

Passing 1 inch screen - 0-1% by weight

B) Manufactured Media

Suitability of size, space, media configuration and

depth will be evaluated on the basis of experience with

installations handling similar wastes and loadings. To

ensure sufficient void clearance, media with a specific

surface area of no more than 30 square feet per cubic

foot may be used for filters employed for carbonaceous

reduction, and media with a specific surface area of no

more than 45 square feet per cubic foot may be used for

second stage ammonia reduction. See subsection (c)(1)

for quality requirements.

4) Handling and Placing of Media

A) Material delivered to the filter site shall be stored on

wood planks or other approved clean hard surfaced areas.

B) All material shall be rehandled at the filter site and

no material shall be dumped directly into the filter.

Crushed rock, slag and similar media shall be rescreened

or forked at the filter site to remove all fines.

C) The material shall be placed by hand to a depth of 12

inches above the tile underdrains and all material shall

be carefully placed so as not to damage the underdrains.

The remainder of the material may be placed by means of

belt conveyors or equally effective methods approved by

the engineer.

D) Manufactured media shall be handled and placed as

recommended by the manufacturer and approved by the

engineer.

E) Trucks, tractors, or other heavy equipment shall not be

driven over the filter during or after construction.

d) Underdrainage System

1) Arrangement

Underdrains with semi-circular inverts or equivalent should

be provided and the underdrainage system shall cover the

entire floor of the filter. Inlet openings into the

underdrains shall have an unsubmerged gross combined area

equal to at least 15 percent of the surface area of the

filter.

2) Slope

The underdrains shall have a minimum slope of 1 percent.

Effluent channels shall be designed to produce a minimum

velocity of 2 feet per second at design average flow of

application to the filter and shall have adequate capacity

for the peak hourly flow rate including the required

recirculation flows.

3) Flushing

Provision should be made for flushing the underdrains. In

small filters, use of a peripheral head channel with vertical

vents is acceptable for flushing purposes. Inspection

facilities should be provided.

4) Ventilation Requirements for Underdrains

The underdrainage system, effluent channels, and effluent

pipe should be designed to permit free passage of air. The

size of drains, channels, and pipe should be such that not

more than 50 percent of their cross-sectional area will be

submerged under the design hydraulic loading. Consideration

should be given in the design of the effluent channels to the

possibility of increased hydraulic loading.

e) Special Features

1) Flooding

Provision shall be made in the design of conventional rock

filter structures so that the media may be flooded.

2) Maintenance

All distribution devices, underdrains, channels and pipes

shall be designed so that they may be properly maintained,

flushed or drained.

3) Flow Measurement

Devices shall be provided to permit measurement of flow to

the filter, and of recirculated flows.

4) Protection From Freezing

Trickling filters shall be covered to protect from freezing,

and to maintain operation and treatment efficiencies. The

filter cover shall be constructed of appropriate corrosion

resistant materials and designed to allow operator access for

maintenance, repair and replacement of the filter dosing

equipment.

5) Ventilation of Covered Filters

Forced ventilation shall be provided for covered trickling

filters to insure adequate oxygen for process requirements.

Windows or simple louvered mechanisms so arranged to insure

air distribution throughout the enclosure shall be provided.

The ventilation facilities shall be designed to allow

operator control of air flow in accordance with outside

temperature. Design computations showing the adequacy of air

flow to satisfy process oxygen requirements shall be

submitted.

f) Two-Stage Filters

The foregoing standards also apply to second stage filters.

g) Special Applications

1) Roughing Filters

In some instances it is desirable to partially reduce the

organic strength of wastewaters. In such cases trickling

filters may be used for roughing treatment. Design

parameters and contaminant removal efficiencies will be

approved on a case-by-case basis. Refer to subsections

(h)(2) and (h)(3).

2) Nitrifying Filters

Trickling filters may, under favorable conditions, be used as

nitrification devices. Design parameters and contaminant

removal efficiencies will be approved on a case-by-case

basis. Refer to Section 370.1210(d).

h) Efficiency

1) Single Stage, Settling Tank -- No Recirculation

Expected reduction of BOD of settled normal domestic

wastewater by a single stage filter, packed with crushed

rock, slag or similar material and with subsequent settling,

shall be determined from Appendix F, Figure No. 3. In

developing this curve, loading due to recirculated sewage

has not been considered.

2) Single or Multi-Stage, Settling Tank -- Recirculation

Expected BOD removal efficiencies may also be determined by

theoretical and empirical formula if accompanied by detailed

explanation, particularly for roughing filters and for

filters with recirculation. (Refer to WEF Manual of Practice

(MOP) No. 8, "Design of Municipal Wastewater Treatment

Plants", vol. 1 (1992).)

3) Single or Multi-Stage, No Settling Tank -- Recirculation

Filters not followed by a settling tank and discharging into

a subsequent treatment process shall not be credited with BOD

removal efficiencies as in subsections (h)(1) and (h)(2)

above. Expected performance in such cases, including filters

packed with manufactured media, shall be determined from

prototype testing and full-scale plant experience.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

(Source: Repealed at 21 Ill. Reg. 12444, effective August 28, 1997)

a) General

Wastewater treatment facilities that propose to use rotating

biological contactors (RBCs) shall submit to the Agency for review

field experience and operational data that demonstrates that

observed problems with the process have been solved at similar

full scale installations. The Agency will review the claimed

field experience against known field conditions and the

operational history of observed problems at similar facilities.

b) Mechanical Reliability and Structural Integrity

1) The mechanical and structural reliability of the shafts and

media subjected to cyclic stress reversals must be

demonstrated relative to the design life of the plant and the

known weight of the machines based on field experience.

2) The design must show that film thickness will be effectively

controlled throughout all parts of the media pack to prevent

excessive film weight and water pickup weight due to plugging

restrictions. The equipment design must include load cells

to warn of the need for film thickness control and to

demonstrate the effectiveness of the proposed film thickness

control practices.

c) Process Reliability

1) Process reliability must be demonstrated, including proven

operational control procedures relative to design organic

loadings for the unit media area or volume, which

satisfactorily insure that the applicable effluent standards

are met. The process design shall also include proven

operational control procedures that will prevent process

functional deficiencies and media plugging that cause the

weight to exceed shaft and media structural capabilities

during the design life of the plant.

2) The design must show that adequate void clearance (as

distinguished from void ratio) is provided to insure that the

biological film, including any grease and fats that may

accumulate, will not interefere with the flow of liquid and

air in the media pack. The Agency will compare the RBC

designs under review to past experience with designs used for

plastic trickling filter media to accomplish adequate void

clearance.

3) The design shall provide for maintaining a minimum of 2.0

mg/l dissolved oxygen in the basin liquor. The effectiveness

of the proposed method for maintaining adequate dissolved

oxygen will be evaluated based on field experience at similar

full scale installations.

4) If pilot testing is proposed, the size of the RBC pilot plant

unit and the scope and duration of the testing program on the

specific waste that will be treated must be thoroughly

documented. The proposed pilot testing program should be

submitted to the Agency for comment prior to the initiation

of testing. The RBC pilot units must be of prototype scale.

Because of differential seasonal weight and plugging field

problems, the test period must cover the four seasons, to

allow the Agency to evaluate the proposed design against the

experience of existing full scale plants.

5) The process design must include provisions for meeting

applicable effluent limits with some units out of service for

unit repair, biofilm thickness control, out-of-balance

correction and other operational problems. Added units for

standby credit will be required to insure compliance with

effluent limitations and to prevent mechanical or structural

failures during periods of unit outage for maintenance,

repair, or process control purposes.

(Source: Added at 21 Ill. Reg. 12444, effective August 28, 1997)

a) General

1) Applicability

A) Biodegradable Wastes

The activated sludge process, and its various

modifications, may be used to treat wastewater which is

amenable to biological treatment. Approval of new

activated sludge plants shall be limited to those plants

where the design average flow capacity exceeds 0.25 mgd.

B) Operation Control Requirements

The activated sludge process requires close attention

and competent operating supervision. Facilities and

appurtenances for routine control and control tests

shall be provided at all activated sludge plants.

These requirements shall be considered when proposing

this type of treatment.

C) Energy Requirements

This process requires major energy usage to meet

aeration demands. Energy costs and potential mandatory

emergency public power reduction events, in relation to

critical water quality conditions, must be carefully

evaluated. Capability of energy usage phasedown while

still maintaining process viability, both under normal

and emergency energy availability conditions, must be

included in the activated sludge design.

2) Specific Process Selection

The activated sludge process and its several modifications

may be employed to accomplish varied degrees of removal of

suspended solids and reduction of 5-day BOD and nitrogenous

oxygen demand. Choice of the process most applicable will be

influenced by the proposed plant size, type of waste to be

treated, treatability of waste, degree and consistency of

treatment required and local factors. All designs shall

provide for flexibility in operation. All plants shall be

designed to operate in at least two modes.

3) Winter Protection

Units shall be protected against freezing. Maximum

utilization of earthen bank insulation shall be considered.

4) Process Efficiency

The activated sludge process designed within the organic and

hydraulic loading limits of these standards, treating normal

domestic wastewaters unaffected by surge loadings, long term

peak flows, or industrial wastes, may be expected to meet an

effluent standard of 20 mg/l CBOD[5] or BOD[5] and 25 mg/l

suspended solids when computed on a 30-day monthly average

basis. Those installations which are anticipated to be

subject to surge loadings, long term peak flows or

industrial wastes shall have appropriate design

modifications in order to assure consistent effluent

quality.

b) Preliminary Treatment

Effective removal of grit, debris, excessive oil and grease and

screening of solids shall be accomplished prior to the activated

sludge process. Where primary settling does not precede the

activated sludge process, screening with 1/2 inch or smaller clear

opening is recommended in order to prevent plugging of return

sludge piping and pumps.

c) Primary Treatment Bypass

When primary settling is used, provision shall also be made for

discharging raw sewage directly to the aeration tanks following

preliminary treatment.

d) Process Organic Loadings

The aeration tank capacities and permissible loadings for the

several adaptations of the processes shown in the table shall be

used.

Permissible Organic Loading

For The Activated Sludge Processes

For Normal Domestic Sewage*

Aeration Tank

Organic Loading,

Process Mode Plant Design lbs BOD[5]/day/

Average Flow 1000 cu. ft.

_______________________________________________________________

Conventional, Less than 1 mgd

Complete Mix, Contact 35

Stabilization,**

Step Aeration,

Tapered Aeration

1 mgd or greater 50

_______________________________________________________________

Extended Aeration 15***

Single Stage Nitrification

_______________________________________________________________

* Where significant industrial wastes will be tributary to the

process, design modification shall be made as required by

subsection (a)(4), to assure compliance with effluent standards.

** Total aeration capacity includes both contact and reaeration

capacities.

*** Detention time at Design Average Flow for extended aeration shall

be 24 hours. This requirement may govern tank capacity. Detention

time for single stage activated sludge for nitrification is

governed by Section 370.1210(c)(3)(B).

e) Aeration Tanks

1) Multiple Units

Multiple tanks shall be provided. Tanks shall be designed so

that each tank may be dewatered and operated independently.

2) Tank Geometry

The dimensions of each independent mixed liquor aeration tank

or return sludge reaeration tank shall be such as to

maintain effective mixing and utilization of air. Liquid

depths should not be less than 10 feet. The shape of the

tank, the location of the inlet and outlet and the

installation of aeration equipment shall provide for

positive control of short-circuiting through the tank.

3) Freeboard

All aeration tanks shall have a freeboard of not less than 18

inches. Greater heights are desirable. Suitable water spray

systems or other approved means of froth and foam control

shall be provided if foaming is anticipated.

4) Inlet and Outlet Control

Inlets and outlets for each aeration tank unit shall be

suitably equipped with valves, gates, stop plates, weirs, or

other devices to permit balancing, proportioning, and

measuring the flow to and from any unit and to maintain

reasonably constant liquid level. The hydraulic elements of

the system shall permit the design peak flow to be carried

with any single aeration tank out of service.

5) Conduits

Channels and pipes carrying liquids with solids in suspension

shall be designed to maintain self-cleansing velocities or

shall be agitated to keep such solids in suspension at all

design rates of flow. Adequate provisions should be made to

drain segments of channels which are not being used due to

alternate flow patterns.

f) Aeration Equipment

1) General

A) Aeration requirements depend upon mixing energy, BOD

loading, degree of treatment, oxygen uptake rate, mixed

liquor suspended solids concentration and sludge age.

Aeration equipment shall be capable of maintaining a

dissolved oxygen concentration of 2.0 mg/1 in the

aeration tanks under all design loads. Energy transfer

shall be sufficient to maintain the mixed liquor solids

in suspension.

B) In the case of nitrification, the oxygen requirement for

oxidizing ammonia must be added to the above requirement

for carbonaceous BOD removal. The nitrogen oxygen

demand (NOD) shall be taken as 4.6 times the diurnal

peak ammonia (as nitrogen) content of the influent. In

addition, the oxygen demands due to recycle flows such

as sludge processing, return from excess flow first

flush storage and other similar flows, must be taken

into account due to the high concentrations of BOD and

ammonia associated with such flows.

C) Careful consideration should be given to maximizing

oxygen utilization per unit power input. Unless flow

equalization is provided, the aeration system should be

designed to match the diurnal organic load variation

while economizing on power input.

2) Diffused Air Systems

A) Except as noted in subsection (f)(2)(B) below, normal

aeration tank air requirements shall be based upon a

design figure of 1,500 cu. ft. of air supplied/lb. of

BOD[5] applied to the aeration tanks. This design

figure assumes that the equipment is capable of

transferring 1.0 lb. of oxygen to the aeration tank

contents/lb. of BOD[5] applied to the aeration tank. For

the extended aeration process, air requirements shall

be based on a design figure of 2250 cu. ft. of air

supplied per lb. of BOD[5] applied to the aeration tanks

to account for oxygen demand for endogenous respiration

and ammonia (as nitrogen) for normal strength waste.

Refer to Section 370.1210(c) for nitrification

requirements.

B) Air requirements may be determined based upon

transferring 1.0 lb. oxygen/lb. of applied oxygen

demand, as determined by subsection (f)(1) above, using

standard equations incorporating the factors listed

below. When using this design technique, the field

oxygen transfer efficiency of the equipment shall be

included in the specifications, and the detailed design

computations shall be contained in the basis of design:

i) Tank depth;

ii) Alpha factor of the waste;

iii) Beta factor of the waste;

iv) Documented aeration device transfer efficiency;

v) Minimum aeration tank dissolved oxygen

concentrations;

vi) Critical wastewater temperature;

vii) Plant altitude.

C) In the absence of experimentally determined alpha and

beta factors for the design described in subsection

(f)(2)(B) above, wastewater transfer efficiency shall be

assumed to be no more than 50% of clean water efficiency

for plants treating primarily (90% or greater) domestic

sewage. Treatment plants whose waste contains higher

percentages of industrial wastes shall use a

correspondingly lower percentage of clean water

efficiency and shall submit calculations to justify such

a percentage. The design wastewater oxygen transfer

efficiency of the equipment shall be included in the

specifications.

D) The specified capacity of blowers or air compressors,

particularly centrifugal blowers, should take into

account that the air intake temperature may reach 115

F or higher and the pressure may be less than normal.

The specified capacity of the motor drive should also

take into account that the intake air may be -20 F or

less and may require oversizing of the motor or a means

of reducing the rate of air delivery to prevent

overheating or damage to the motor.

E) The blowers shall be provided in multiple units, so

arranged and in such capacities as to meet the maximum

total air demand with the single largest unit out of

service. The design shall also provide for varying the

volume of air delivered in proportion to the load demand

of the plant.

F) The air diffusion piping shall be capable of delivering

200 percent of the design air requirements. Air piping

systems should be designed such that the friction head

loss from the blower outlet (or silencer outlet where

used) to the diffuser inlet does not exceed 0.5 psi at

100 percent of design air requirements at average

operating conditions for temperature and pressure.

G) The spacing of diffusers should be in accordance with

the oxygenation requirements through the length of the

channel or tank, and should be designed to facilitate

adjustments of their spacing without major revision to

air header piping. Diffusers in any single assembly

shall have substantially uniform pressure loss.

H) Individual assembly units of diffusers shall be equipped

with control valves, preferably with indicator markings

for throttling and for complete shut off. The

arrangement of diffusers shall also permit their

removal for inspection, maintenance and replacement

without dewatering the tank and without shutting off the

air supply in the tank, unless the dewatered aeration

basins are no more than 25% of the total aeration basin

capacity. Total aeration basin capacity shall include

the basins in both stages of a two-stage activated

sludge process.

I) Air filters shall be provided in numbers, arrangement,

and capacities to furnish at all times an air supply

sufficiently free from dust to prevent clogging of the

diffuser system used.

3) Mechanical Aeration Systems

A) Oxygen requirements shall be determined in accordance

with subsections (f)(2)(B) and (f)(2)(C) above.

B) The mechanism and drive unit shall be designed for the

expected conditions in the aeration tank in terms of

the power performance. Certified testing shall verify

mechanical aerator performance. The design field oxygen

transfer efficiency of the equipment shall be included

in the specifications, and the detailed design

computations shall be contained in the basis of design.

C) The mechanical aerators shall be provided in multiple

units, so arranged and in such capacities as to maintain

all biological solids in suspension, meet maximum oxygen

demand and maintain process performance with the largest

unit out of service. Provision shall be made for varying

the amount of oxygen transferred in proportion to the

load demand on the plant.

D) Due to high heat loss, the mechanism as well as

subsequent treatment units shall be protected from

freezing.

E) Motors, gear housing, bearings and grease fittings shall

be easily accessible and protected from inundation and

spray as necessary for proper functioning of the unit.

g) Return Sludge Equipment

1) Return Sludge Rate

The rate of sludge return, expressed as a percentage of

design average flow of sewage, shall be variable between

limits of 15 and 100 percent.

2) Return Sludge Pumps

A) If motor driven return sludge pumps are used, the

maximum return sludge capacity shall be obtained with

the largest pump out of service. The rate of sludge

return shall be varied by such means as variable speed

motors or drives, multiple constant speed pumps, or

telescoping valves. A positive head should be provided

on pump suctions. Pumps shall be capable of passing

spheres of at least 3 inches in diameter. Pump suction

and discharge openings shall be at least 4 inches in

diameter.

B) If air lift pumps are used for returning sludge from

each settling tank, no standby unit shall be required

provided that the design of the air lifts is such as to

facilitate their rapid and easy cleaning. Air lifts

should be at least 3 inches in diameter and provided

with adjustable air valving to permit flow control in

accordance with subsection (g)(1) above.

3) Return Sludge Piping

Suction and discharge piping should be at least 4 inches in

diameter and should be designed to maintain a velocity of not

less than 2 feet per second when return sludge facilities

are operating at normal return sludge rates. Suitable

devices for observing, measuring, sampling and controlling

return activated sludge flow from each settling tank shall

be provided.

4) Waste Sludge Control

Waste sludge control facilities should have a maximum

capacity of not less than 25 percent of the average rate of

sewage flow and function satisfactorily at rates of 0.5

percent of average sewage flow. Means for observing,

measuring, sampling and controlling waste activated sludge

flow shall be provided. Waste sludge may be discharged to

the primary settling tank, concentrator or thickening tank,

sludge digestion tank, vacuum filters, or any practical

combination of these units. Refer to Sections 370.820 and

370.710(b)(1)(A).

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Supplement To Engineer's Report

1) The engineer's report shall contain pertinent information on

location, geology, soil conditions, area for expansion, and

any other factors that will affect the feasibility and

acceptability of the proposed treatment.

2) Supplementary Field Survey Data

The following information must be submitted in addition to

that required in Section 370.111:

A) The location and direction of all residences, commercial

development, and water supplies within 1/2 mile of the

proposed pond.

B) Soil borings to determine surface and subsurface soil

characteristics of the immediate area and their effect

on the construction and operation of a pond located on

the site.

C) Data demonstrating anticipated percolation rates at the

elevation of the proposed pond bottom.

D) A description, including maps showing elevations and

contours of the site and adjacent area suitable for

expansion.

E) Sulfate content of the water supply.

F) Identification of the location, depth and discharge

point of any field tile in the immediate area of the

proposed site.

b) Location

1) Distance From Habitation

A pond site should be as far as practicable from habitation

or any area which may be built up within a reasonable future

period.

2) Prevailing Winds

If practicable, ponds should be located so that local

prevailing winds will be in the direction of uninhabited

areas. Preference should be given sites which will permit an

unobstructed wind sweep across the ponds, especially in the

direction of the local prevailing winds.

3) Surface Runoff

Adequate provisions shall be made to divert storm water

around the ponds and otherwise protect pond embankments.

4) Ground Water Contamination

The requirements of the Illinois Groundwater Protection Act

[415 ILCS 55] shall be taken into account in the siting of

ponds. Ponds should not be located proximate to water

supplies and other facilities subject to contamination or

located in areas of porous soils and fissured rock

formations. If conditions dictate using such a site, then

the potential for and the means necessary to combat

groundwater contamination shall be critically evaluated in

the engineer's report. In such locations, the Agency will

require groundwater monitoring wells.

5) Geology

Ponds shall not be located in areas subject to sink holes and

mine subsidence. Soil borings and tests to determine the

characteristics of surface soil and subsoil shall be made a

part of preliminary pond site selection surveys. Gravel and

limestone areas should be avoided; however, where conditions

dictate locating ponds in such areas and the minimum

separation between the pond bottom and gravel or limestone

will be less than 10 feet, the Agency shall be contacted

about the necessary precautions.

c) Basis Of Design

1) Organic Loading

A) Waste Stabilization Ponds

The organic loading on each cell shall not exceed the

loadings listed below. If more accurate design

information for the particular type waste is not

submitted and supported by the engineer, subsequent

cells shall be sized for an organic loading of 25% of

each preceding cell.

i) North of Illinois Highway 116 (Pontiac) 22 lbs.

BOD per acre per day.

ii) Between Illinois Highway 116 and U.S. Highway 50,

26 lbs. BOD per acre per day.

iii) South of U.S. Highway 50 (Salem-Carlyle) 30 lbs.

BOD per acre per day.

B) Aerated Lagoons

The organic loading for aerated lagoons shall not exceed

0.5 lb. BOD[5] day per 1,000 cu. ft. first cell nor 0.3

lb. BOD[5] day per 1,000 cu. ft. on any subsequent

cells. If more accurate design information for the

particular type waste is not submitted and supported by

the engineer, the second and third cells shall be sized

for an organic loading of 25% of each preceding cell.

2) Depth

A) Waste Stabilization Ponds

The minimum operating liquid depth for waste

stabilization ponds should be 2 feet. The maximum

operating liquid depth shall be based on design storage

requirements and shall not be less than 5 feet.

B) Aerated Lagoons

The design water depth for aerated lagoons should be 10

to 15 feet. This depth limitation may be altered

depending on the aeration equipment, waste strength,

climatic and geological conditions.

3) Aeration Requirements For Aerated Lagoons

A) Aeration systems shall be designed to provide, with the

largest unit out of service, a minimum of 1,500 cu. ft.

of air/lb. of BOD[5] in the raw waste (1.5 lbs. of

oxygen/lb. of BOD[5] plus oxygen required to oxidize

the ammonia present in the raw waste). The aeration

equipment shall be located to ensure proper mixing and

distribution of oxygen in proportion to oxygen demand in

multiple cells. Splash type aerators with motors above

the water surface may not be used.

B) Where hose type diffusers are used, the holes shall be

of sufficient size to prevent plugging by dissolved

solids incrustation.

4) Multiple Cells

A minimum of two cells to be operated in series or parallel

should be provided for all waste stabilization ponds when

they are utilized as a part of the primary and secondary

treatment process. The number of cells required for aerated

lagoons are dependent upon the degree of treatment required.

Refer to subsection (c)(6).

5) Pond Shape

The shape of all primary cells should be such that there are

no narrow or elongated portions. Round, square, or

rectangular ponds with a length not exceeding 3 times the

width are considered most desirable. No islands, peninsulas,

or coves should be permitted. Dikes should be rounded at

corners to minimize accumulations of floating materials.

6) Solids Removal

All lagoon systems shall include effective solids removal

facilities. Design criteria for acceptable solids removal

facilities are contained in Subpart K. Other solids removal

facilities may be approved in accordance with Section

370.520(b).

d) Construction Details

1) Embankments and Dikes

A) Material

Embankments and dikes shall be constructed of relatively

impervious materials and compacted to at least 90%

Standard Proctor density to form a stable structure.

Vegetation and other unsuitable material shall be

removed from the area upon which the embankment is to be

placed.

B) Top Width

The minimum embankment top width should be 8 feet to

permit access of maintenance vehicles. Lesser top

widths will be considered for very small installations.

C) Maximum Embankment Slopes

i) Inner Slopes:

3 horizontal to 1 vertical.

ii) Outer Slopes:

3 horizontal to 1 vertical.

D) Minimum Embankment Slopes

i) Inner Slopes:

4 horizontal to 1 vertical. Flatter slopes are

sometimes specified for larger installations

because of wave action but have the disadvantage of

added shallow areas conducive to emergent

vegetation.

ii) Outer Slopes:

Outer slopes shall be sufficient to prevent surface

runoff from entering the ponds.

E) Freeboard

Minimum freeboard shall be 3 feet except for very small

installations 2 feet may be acceptable.

F) Erosion Control Requirements

For effective erosion control on the lagoon embankments,

both seeding and riprap (or acceptable alternate) are

required.

i) Seeding

Embankments shall be seeded from the outside toe to

1 foot above the high water line on the dikes,

measured on the slope. Perennial type, low

growing, spreading grasses that withstand erosion

and can be kept mowed are most satisfactory for

seeding of embankments. In general, alfalfa and

other long rooted crops should not be used in

seeding, since the roots of this type plant are apt

to impair the water holding efficiency of the

dikes. The County Agricultural Extension Agent

can usually advise as to hardy, locally suited

permanent grasses which would be satisfactory for

embankment seeding.

ii) Riprap

Riprap (or acceptable alternate) shall be placed on

the inner slope of the embankments from 1 foot

above the high water mark to 1 foot below the low

water level. Riprap shall be comprised of a

two-layer system consisting of a minimum 4-inch

layer of coarse aggregate that meets the Illinois

Department of Transportation (IDOT) Standard

Specification for Road and Bridge Construction

adopted January 1, 1997 for the gradations in the

range of CA-6 through CA-10 and a minimum 12-inch

layer of stone. The rock layer shall consist of

evenly graded material with a maximum weight of 150

pounds per piece and shall meet the IDOT gradations

for rock of either Grade No. 3 or 4.

2) Pond Bottom

A) Uniformity

Finished elevations shall not be more than 3 inches from

the average elevation of the bottom. Shallow or

feathering fringe areas usually result in locally

unsatisfactory conditions.

B) Vegetation

The bottom shall be cleared of vegetation and debris.

Organic material thus removed shall not be used in the

dike core construction. However, suitable topsoil

relatively free of debris may be used as cover material

on the outer slopes of the embankment.

C) Soil

Soil used in constructing the pond bottom (not including

the seal) shall be relatively incompressible and tight.

Porous topsoil shall be removed. Porous areas, such as

gravel or sandy pockets, shall be removed and replaced

with well compacted clay. The entire bottom shall be

compacted at or up to 4% above the optimum water content

to at least 90% Standard Proctor density.

D) Seal

The pond bottom and embankments shall be sealed such

that seepage loss through the seal is as low as

possible. Seals consisting of soils, bentonite or

synthetic liners may be used, provided that the

permeability, durability and integrity of the proposed

material is demonstrated for anticipated conditions.

The results of a testing program that substantiates the

adequacy of the proposed seal shall be incorporated into

or accompany the engineering report. Standard ASTM

procedures or similar accepted testing methods shall be

used for all tests.

i) A seal consisting of soil materials shall have a

thickness of at least 24 inches and a permeability

of less than 1x10(-7) cm per second. Provision

shall be made in the specifications for

demonstrating the permeability of the seal after

completion of construction and prior to filling the

pond.

ii) For a seal that consists of a synthetic liner,

seepage loss through the liner shall not exceed a

quantity equivalent to seepage loss through a soil

seal as described above.

E) Prefilling

Prefilling the pond after completion of testing is

recommended in order to protect the seal from weed

growth, to prevent drying and cracking and to reduce

odor during initial operation. The pond dikes must be

completely prepared as described in subsection

(d)(1)(F). Synthetic liners shall be protected from

damage during installation and filling.

3) Influent Lines

A) Material

Any generally accepted material for underground sewer

construction will be given consideration for the

influent line to the pond. The material selected should

be adapted to local conditions. Special consideration

must be given to the character of the wastes,

possibility of septicity, exceptionally heavy external

loadings, abrasion, the necessity of reducing the number

of joints, soft foundations, and similar problems.

B) Manholes

A readily accessible manhole shall be installed at the

terminus of the trunk sewer or the force main, unless

the force main discharges directly to the lagoon as

described in subsection (d)(3)(H). The manhole shall be

located as close to the dike as topography permits and

its invert should be at least 6 inches above the maximum

operating level of the pond to provide sufficient

hydraulic head without surcharging the manhole.

Surcharging of the sewer upstream from the inlet manhole

is not permitted.

C) Grade

i) Influent line can be placed at zero grade and

should be located along the bottom of the pond so

that the top of the pipe is just below the average

elevation of the pond bottom. The pipe shall have

adequate seal below it.

ii) The laying of the influent pipe on the surface of

the pond bottom is prohibited.

D) Point of Discharge

Influent lines to the primary cell should terminate at

approximately the third point farthest from the outlet

structure. For interconnecting piping to secondary

cells refer to subsection (d)(4)(B).

E) Flow Distribution

Flow distribution structures shall be designed to

effectively split hydraulic and organic loads

proportionally to primary cells. Refer to Section

370.520(f).

F) Submerged Inlets

Submerged inlet lines shall discharge horizontally into

a shallow, saucer-shaped depression which should extend

below the pond bottom not more than the diameter of the

influent pipe plus 1 foot.

G) Discharge Apron

The end of the discharge line should rest on a suitable

concrete apron with a minimum size of 2 feet square.

H) Force Mains

Force mains discharging directly to lagoons are

permitted if the force main has a freefall discharge

into the lagoon and is not turned upward at the point of

discharge. The point of discharge shall be at

approximately the third point farthest from the outlet

structure and the pipe shall be sloped for drainage into

the lagoon to avoid freezing.

I) Anti-Seep Collars

Anti-seep collars shall be used on all piping passing

through or under the lagoon embankments.

4) Outlet Structures and Interconnecting Piping

A) Outlet Structure

i) Outlet structures shall be designed to allow the

operating level of the pond to be adjusted to

permit operation at depths of 2 feet to the maximum

depth. The design shall also allow effluent to be

drawn from various depths below all operating

levels. All structures and devices such as weirs,

gates and valves shall be watertight and capable of

being easily adjusted by the operator without the

need of additional mechanical equipment. Wooden

stop-planks are not acceptable for level control.

ii) Drawoff lines should not be located any lower than

12 inches off the bottom to control eroding

velocities and avoid pickup of bottom deposits.

iii) A locking device should be provided to prevent

unauthorized access to the level control

facilities.

iv) When possible, the outlet structure should be

located on the windward side to prevent short

circuiting. The outlet structure shall be properly

baffled to prevent the discharge of floating

material.

v) Consideration must be given in the design of all

structures to protect against freezing or ice

damage under winter conditions.

B) Interconnecting Piping and Unit Bypass

i) Interconnecting piping and overflows should be

constructed of materials that will withstand damage

during construction and operation, giving special

consideration to damage that may occur during

compaction of embankments and damage to shallow

piping. Piping shall be sized to allow transfer of

maximum flows without raising the lagoon water

level by more than 6 inches in the upstream cell.

In no case shall interconnecting pipe be less than

8 inches in diameter. Interconnecting piping

between cells should be valved or provided with

other arrangements to regulate flow between

structures and permit flexible depth control.

ii) The interconnecting pipe to the secondary cell

should discharge horizontally near the lagoon

bottom to minimize need for erosion control

measures and should be located as near the dividing

dike as construction permits.

iii) Piping and valves shall be provided so that each

cell can be operated independently of any other

cell. Provision shall be made for independent cell

dewatering.

C) Anti-Seep Collars

Anti-seep collars shall be used on all interconnecting

and outlet piping passing through or under the lagoon

embankments.

5) Miscellaneous

A) Fencing

The pond area shall be enclosed with a suitable fence to

preclude livestock and discourage trespassing. A

vehicle access gate of sufficient width to accommodate

mowing equipment shall be provided. All access gates

shall be provided with locks.

B) Warning Signs

Appropriate signs should be provided along the fence

around the pond to designate the nature of the facility

and advise against trespassing.

C) Flow Measurement, Sampling and Level Gauge

Provisions for flow measurement and sampling shall be

provided on the inlet and outlet. Pond level gauges

shall be provided. The NPDES permit monitoring

requirements for the facility shall be taken into

account. Elapsed time meters on pumps or calibrated

weirs may be used as flow measurement devices for

lagoons.

D) Sludge Removal

When an existing lagoon is to be upgraded, the project

design shall provide for removal of any sludge

accumulation in the existing lagoon. The sludge removed

shall be disposed of in accordance with IPCB

regulations.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Applicability

Use of the intermittent sand filter for secondary treatment is

generally limited to weak to normal strength wastewaters which are

amenable to biological treatment. Cold weather operational

problems may preclude the use of this process unless the influent

temperature to the filter is adequate to allow efficient filter

operation necessary to meet the applicable effluent standards.

b) Pretreatment Requirements

Wastewaters applied to intermittent sand filters must be

substantially free of grit, debris, oil and grease, floating and

suspended materials, and components which inhibit biological

processes and cause rapid clogging of the filter. Special

consideration shall be given to the design of preceding treatment

units, including dosing facilities, to limit heat loss during

winter operation.

c) Multiple Units

Intermittent sand filters shall be provided in multiple units,

designed for independent operation and maintenance.

d) Location

Intermittent sand filters treating septic tank or primary effluent

should be restricted to relatively isolated locations or otherwise

modified in order to minimize odor nuisances.

e) Recirculation

Recirculation of filter effluent may be practiced in order to

attenuate and equalize organic and hydraulic loads to the filter,

and improve unit process efficiency, control odors, and improve

day-to-day reliability.

1) Rate

A recirculation rate of up to 300% of the settled sewage load

to the filter may be provided.

2) Variability

The capability of varying the recirculation rate allows

greater process control and optimization of process

efficiency. This feature shall be included where

recirculation is provided.

f) Dosing

1) Dosing Volumes

The dosing facilities shall be designed for a capacity of

2,500 gallons per 1,000 sq. ft. of filter bed to be dosed at

any given time.

2) Dosing Rates for Siphons or Pumps

Siphons (at minimum head) or pumps shall have a discharge

capacity at least 100% in excess of the maximum rate of

inflow to the dosing tank, including recirculation, and at

average head, at least 90 gallons per minute per 1,000 square

feet.

3) Discharge Line Capacity

The discharge lines to the beds shall have sufficient

capacity to permit the full rated discharge of the siphons or

pumps.

g) Construction Details

1) Earth Base

The earth base of the filters shall be sloped to the

underdrains.

2) Underdrains

The sand filter shall be provided with open-joint or

perforated pipe underdrains. They should be sloped to the

outlet and spaced not to exceed 10 foot centers. Vertical

riser vents shall be provided at both ends of each underdrain

pipe and shall be located as not to be overtopped at maximum

dosing depth.

3) Media

A) Gravel Base

Clean graded gravel, preferably placed in at least three

layers, should be placed around the underdrains and to a

depth of at least 6 inches over the top of the

underdrains. Crushed stone may not be used in lieu of

gravel. Suggested gradings for the three layers are:

1 1/2" to 3/4", 3/4" to 1/4", 1/4" to 1/8".

B) Sand

At least 24 inches of clean washed sand shall be

provided. Sand shall be durable and relatively

insoluble in sewage. Clay content shall be less than 1%

by weight. The effective size shall be 0.3 to 1.0

millimeter (mm). The uniformity coefficient shall not

be greater than 3.5.

4) Splash Slabs

Splash slabs shall be provided at each point of discharge to

the filter. A means of dissipating the energy of the

discharge velocity shall be provided around the periphery of

the splash slab.

5) Curbs

Provision shall be made to prevent soil and surface runoff

from entering the filter area. Curbs should be high enough

to hold the maximum dose and provide adequate freeboard.

6) Distribution System

A) Arrangement

Provision shall be made for even distribution of the

flow on the filter surface. If troughs or piping are

used, they shall be so located that the maximum lateral

travel of the flow on the media surface is not more than

20 feet.

B) Drains

Troughs, discharge piping or other distribution

equipment shall be sloped to drain to prevent freezing.

h) Loading Rates

The loading rates shall be based on the raw sewage flow and

organic strength. The following loading rates shall not be

exceeded:

Raw Waste Strength Dose Rate

(BOD[5] mg/l) (gals./ft.(2)/day)

_______________ __________________

100 to 200 3

200 to 300 2

above 300 1

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

SUBPART J: DISINFECTION

Where needed to meet applicable standards, disinfection of the effluent

shall be provided. The design shall provide for meeting both the bacterial

standards and any disinfectant residual limits applicable to the effluent.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) The disinfection process should be selected after due

consideration of waste characteristics, type of treatment

processes provided prior to disinfection, waste flow rates, waste

pH, disinfectant demand rates, current technology application,

cost of equipment, chemical availability, power costs and

maintenance requirements. Areawide public safety shall be

considered where large liquid chlorine or sulfur dioxide

containers are to be handled.

b) Chlorine may be used in the form of liquid chlorine or calcium or

sodium hypochlorite. Dechlorination will be required where

necessary to meet applicable chlorine residual effluent

limitations.

c) An ultra-violet radiation system may be used as an alternative

disinfection process.

d) Other alternative means of disinfection will be evaluated

according to the provisions of Section 370.520(b).

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Type of Feed Equipment

The types of chlorine feed equipment include:

1) Vacuum solution feed by gas;

2) Direct gas feed;

3) Hypochlorite solution positive displacement pump feed;

4) Hypochlorite tablet feed.

b) Selection of Feed Equipment

The selection of the type of chlorine feed equipment shall take

into account operator safety and overall public safety relative to

the proximity of the sewage treatment plant to populated areas and

to the security of the gas cylinder or container storage.

c) Output Capacity of Gas Chlorine Cylinders

Ambient 100 pound 150 pound 1 Ton

Temp. F Cylinder Cylinder Container

40 6 9 100

50 14 21 240

60 23.7 35.5 385

70 32 47.5 536

80 41.2 62 700

Some types of vacuum chlorinators can deliver chlorine at rates

greater than those listed above under the same conditions. When

designs include rates in excess of those indicated above,

manufacturer's specifications and test results shall be provided.

d) Standby Equipment and Spare Parts

Standby equipment of sufficient capacity should be available to

replace the largest unit during shutdowns. Spare parts shall be

available for all chlorinators to replace parts which are subject

to wear and breakage.

e) Potable Water Supply Protection

An ample supply of water shall be available for operating the

chlorinator. Where a booster pump is required, duplicate

equipment should be provided and, when necessary, also standby

power (refer to Section 370.550(a)(4)). Protection of a potable

water supply shall conform to the requirements of Section

370.550(b)(3). In-line backflow preventers are not acceptable.

f) Chlorine Gas Supply

1) Cylinders

The use of 1-ton containers should be considered where the

average daily chlorine gas consumption is over 150 pounds.

All upright chlorine cylinders shall be strapped securely to

prevent tipping.

2) Tank Cars

A) At large installations the use of tank cars, generally

accompanied by evaporators, may be considered. Areawide

public safety shall be evaluated as a part of the

considerations. Provision shall be made for a chlorine

supply during tank car switching.

B) The tank car being used for the chlorine supply shall be

located on a dead end, level track that is a dedicated

siding. The tank car shall be protected from accidental

bumping by other railway cars by a locked de-rail

device, a closed lock switch, or both. The area shall

be clearly posted "DANGER-CHLORINE." The tank car shall

be secured by adequate fencing with locked gates for

personnel and rail access.

C) The tank car site shall be provided with an operating

platform at the unloading point that allows for easy

access to the protective housing on the tank car for

flexible feed line connection and valve operation. Area

lighting adequate for night time operation and

maintenance shall be provided.

3) Scales

A) Scales shall be provided for weighing cylinders and

containers at all plants using chlorine gas.

B) At large plants, indicating and recording scales are

recommended. At a minimum, a platform scale shall be

provided. Scales shall be made of corrosion-resistant

material. Scales should be recessed unless hoisting

equipment is provided or the scales are low enough to

allow the cylinders to be rolled onto them.

4) Evaporators

Where manifolding of several cylinders or containers will be

required to evaporate sufficient chlorine, consideration

should be given to liquid drawoff and installation of an

evaporator.

5) Leak Detection and Controls

A bottle of ammonium hydroxide solution should be available

for detecting chlorine leaks. Consideration should also be

given to the provision of caustic soda solution reaction

tanks for absorbing the contents of leaking 1-ton containers

where such containers are in use. Also, when cylinders,

containers or tank cars are used, a leak repair kit approved

by the Chlorine Institute shall be provided. At

installations using over 150 pounds of chlorine gas per day

consideration should be given to the installation of

automatic gas detection and related alarm equipment.

g) Piping and Connections

1) Piping systems should be as simple as possible, and shall be

specially selected and manufactured to be suitable for

chlorine service, with a minimum number of joints. Piping

should be well supported and protected against temperature

extremes.

2) The chlorine system piping shall be color coded and labeled

to distinguish it from sulfur dioxide and other plant piping.

Where sulfur dioxide is used, the piping and fittings for

chlorine and sulfur dioxide systems shall be designed so that

interconnection between the two systems cannot occur.

h) Housing

1) Container and Equipment Location

Containers and feed equipment should be located indoors, in a

suitable fire-resistant building. Gas cylinders should be

protected from direct sunlight if not located indoors.

A) Separation

If gas chlorination equipment and chlorine cylinders or

containers are to be housed in a building used for other

purposes, the chlorine cylinders or containers and

equipment shall be located in an isolated room. This

room shall not contain any sulfonation equipment, sulfur

dioxide cylinders or other equipment unrelated to

chlorination. Common walls to other areas of the

building shall be gastight. Doors to this room shall

open only to the outside of the building and shall be

equipped with panic hardware. Rooms shall be at ground

level and shall permit easy access to all equipment.

Storage areas should be separated from the feed area.

B) Inspection Window

A clear gastight window shall be installed in the

chlorinator room to permit the units to be viewed and

gauges to be read without entering the room.

C) Heat

Chlorinator housing facilities shall be provided with a

means of heating so that a temperature of at least 60 F

can be maintained. Where chlorine gas is to be

withdrawn from cylinders or containers, the cylinders or

containers shall be maintained at essentially room

temperature. The room shall be protected from excessive

heat. If liquid chlorine is to be withdrawn from the

cylinders or containers to an evaporator unit, the feed

cylinders or containers may be located in an unheated

area.

3) Ventilation For Gas Chlorination Systems

A) Forced, mechanical ventilation shall be installed which

will provide 1 complete air change per minute. The

entrance to the air exhaust duct from the room shall be

within 12 inches of the floor and the point of discharge

shall be so located as not to contaminate the air in the

immediate vicinity of the entrance door to the

chlorinator room or ventilation inlet or window or

entrance door to any buildings or inhabited areas.

Where the public may be subjected to extensive exposure

to chlorine in case of chlorine leaks, scrubbers may be

required on the ventilation discharge.

B) The chlorination room air inlets shall be so located as

to provide cross ventilation with air and at such

temperature that will not adversely affect the

chlorination equipment. The vent hose from the

chlorinator shall discharge to the outside atmosphere

above grade.

4) Electrical Controls

The controls for the fans and lights shall be provided at

those locations where it is necessary to enter the

chlorination room and shall automatically operate when the

door is opened and continue to operate when the operator

enters the room and the door is closed. Provision shall be

made for manual operation of controls from the outside of the

room without opening the door.

5) Outdoor Cabinet Housing

Outdoor shallow cabinet-type units, with wide opening doors,

that are shallow enough not to need or require operator

entry, may be used to house the containers and feed

equipment. Use of such cabinets shall be limited to small

plants that provide seasonal disinfection or use less than 10

pounds of chlorine per day. Only two chlorine gas cylinders

of 150 pounds or less on line may be housed in the cabinets.

The following items shall be provided for in the design:

A) The cabinet structure shall be located on and securely

anchored to a concrete slab sized to allow for safe

transport and handling of the cylinders. The structure

and slab shall be capable of withstanding expected wind

loadings on the cabinet. The design of the cabinet

support slab shall take into account the effects of

frost and settling due to soil stability. Flexible

piping connections should be considered for lines

connected to the cabinet.

B) The cabinet shall be protected from direct sunlight to

prevent overheating of the chlorine cylinders.

C) The cabinet doors shall extend the full width of the

long side of the cabinet structure so that the full

interior of the cabinet is exposed with the door open.

Provision shall be made to secure the open doors while

the operator is changing cylinders and maintaining the

feed equipment.

D) The cabinet depth shall not exceed 24 inches. The feed

equipment shall be positioned to allow easy access for

maintenance and to allow observation of the gauges and

meters.

E) Provision shall be made for chains, wall mounted

fastener hooks or similar means for anchoring the

chlorine cylinders to prevent tipping.

F) The cabinet structure shall be corrosion resistant to

chlorine gas.

G) Where electrical power is available, the cabinet should

be placed in a well-lighted area.

i) Respiratory Protection Equipment

Respiratory protection equipment meeting the requirements of the

National Institute for Occupational Safety and Health (NIOSH)

shall be available at all installations where chlorine gas is

handled and shall be stored in a convenient location outside of

any room where chlorine is used or stored. The respiratory

protection units shall use compressed air, have at least a

30-minute capacity, and be compatible with or exactly the same as

NIOSH-approved units used by the local fire department.

Instructions for using, testing, and replacing mask parts shall be

posted. At large installations, consideration should be given to

providing acid suits and fire suits.

j) Application of Chlorine

1) Contact Period

After thorough mixing, a minimum contact period of 15 minutes

at design peak hourly flow or maximum rate of pumpage shall

be provided.

2) Chlorinator Dosing Rate Capacity

Chlorinators shall be designed to have a capacity adequate to

produce an effluent that will meet the applicable bacterial

limits. Where necessary to meet the operating ranges,

multiple units shall be provided for adequate peak capacity

and for a sufficiently low feed rate on turn down to allow

proper chlorine residual. The chlorination system shall be

designed on a rational basis and calculations justifying the

equipment sizing and number of units shall be submitted for

the whole operating range of flow rates, including the

minimum turn down capacity for the type of control to be

used. System design considerations shall include the

controlling sewage flow meter (sensitivity and location),

telemetering equipment and chlorinator controls. For treated

normal domestic sewage the following dosing capacity, based

on design average flow, is suggested (see Section

370.520(c)(1)):

Primary Settled Sewage 20

Lagoon Effluent (unfiltered) 20

Trickling Filter Plant Effluent 10

Lagoon Effluent (filtered) 10

Activated Sludge Plant Effluent 6

Activated Sludge Plants with

Chemical Addition 4

Filtered Effluent Following

Mechanical Biological Treatment 4

k) Contact Tank

1) Mechanical means of sludge removal is recommended and should

be provided unless multiple chlorine tanks are provided.

Portable deck-level vacuum cleaning equipment may be used for

small treatment plants. Provisions for draining contact

tanks not equipped with mechanical sludge removal equipment

shall be provided, with the drain flow returned to process

for treatment.

2) Exception to the requirement of duplicate contact tanks may

be granted if the contact tank follows a sand filter or if

the main treatment works is a waste stabilization pond, with

provisions for storing the sewage flow for several days while

the contact tank is being cleaned.

3) Adequate mixing during the chlorine contact period shall be

insured by the installation of adequate baffling, air or

other mixing equipment. Facilities for the retention and

removal of floating scum shall be provided.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) General

Dechlorination of sewage plant effluents may be required to reduce

toxicity due to chlorine residuals.

b) Feed Equipment

1) Type

The common types of dechlorination feed equipment using

sulfur compounds include:

A) Vacuum solution feed of sulfur dioxide gas.

B) Positive displacement pump feed or aqueous solutions of

sulfite or bisulfite products.

2) Selection of Feed Equipment

The selection of the type of feed equipment using sulfur

compounds shall include consideration of operator safety and

overall public safety relative to the proximity of the sewage

treatment plant to populated areas and the security of the

gas cylinder storage. The selection and design of sulfur

dioxide feeding equipment shall take into account the fact

that the gas reliquifies very easily.

c) Output Capacity of Sulfur Dioxide Cylinders

The number of feed cylinders or containers necessary to meet the

design delivery rates shall be based on the physical,

thermodynamic and chemical properties for sulfur dioxide. Refer

to the Compressed Gas Association publication CGA G-3-1988 "Sulfur

Dioxide" or other standard reference sources for information on

sulfur dioxide properties.

d) Standby Equipment and Spare Parts

Standby equipment should be available of sufficient capacity to

replace the largest unit during shutdown. Spare parts to replace

parts that are subject to wear and breakage shall be available for

all sulfonators.

e) Potable Water Supply

An ample supply of water shall be available for operating the

sulfonator. Where a booster pump is required duplicate equipment

should be provided and, when necessary, standby power. (Refer to

Section 370.550(a)(4).) Protection of the potable water supply

shall conform to the requirements of Section 370.550(b)(6).

In-line back flow preventers may not be used.

f) Sulfur Dioxide Gas Supply

1) Cylinders

The use of 1-ton containers should be considered where the

average daily sulfur dioxide consumption is over 150 pounds.

All upright sulfur dioxide cylinders shall be strapped

securely to prevent tipping.

2) Tank Cars

A) The use of tank cars, generally accompanied by

evaporators, may be considered for large installations.

Areawide public safety shall be evaluated as part of the

considerations. Continuity of sulfur dioxide supply

shall be maintained during tank car switching.

B) The tank car being used for the sulfur dioxide supply

shall be located on a dead end, level track that is a

dedicated siding. The tank car shall be protected from

accidental bumping by other railway cars by a locked

de-rail device, a closed lock switch, or both. The area

shall be clearly posted "DANGER-SULFUR DIOXIDE." The

tank car shall be secured by adequate fencing with

locked gates for personnel and rail access.

C) The tank car site shall be provided with an operating

platform at the unloading point that allows for easy

access to the protective housing on the tank car for

flexible feed line connection and valve operation. Area

lighting adequate for night time operation and

maintenance shall be provided.

3) Scales

A) Scales shall be provided for weighing cylinders or

containers at all plants using sulfur dioxide gas.

B) At large plants indicating and recording scales are

recommended. At a minimum, a platform scale shall be

provided. Scales shall be made of corrosion resistant

material. Scales should be recessed unless hoisting

equipment is provided or the scales are low enough to

allow the cylinders to be rolled onto them.

4) Evaporator

Where the manifolding of several cylinders or containers will

be required to evaporate sufficient sulfur dioxide,

consideration should be given to liquid drawoff and

installation of an evaporator. A liquid nitrogen gas padding

system to enhance the liquid sulfur dioxide delivery rate

should be considered.

5) Leak Detection and Controls

Sulfur dioxide leak detection equipment shall be provided

which has a sensitivity level equal to that of ambient air

pollution monitoring equipment. Where cylinders, one-ton

containers and tank cars are used, a leak repair kit that is

compatible for use with sulfur dioxide gas shall be provided.

Leak repair kits used for chlorine gas (Section

370.1020(f)(5)) equipped with gasket materials suitable for

service with sulfur dioxide may be used. (See paragraphs

10.4 and 13.2 of "Sulfur Dioxide," Compressed Gas

Association, Inc., Publication CGA G-3-1988 for a discussion

of suitable materials.) Refer to Section 370.560.

g) Piping and Connections

1) Piping systems should be as simple as possible, with a

minimum number of joints, and shall be suitable for sulfur

dioxide service. Piping should be well supported and

protected against temperature extremes.

2) The piping for the sulfur dioxide system shall be color-coded

and labeled to distinguish it from chlorine piping, and the

system shall be designed so that interconnections with

chlorine piping cannot occur.

h) Housing

1) Container and Equipment Location

Containers and feed equipment should be located inside a fire

resistant building. Gas cylinders and containers should be

protected from direct sunlight.

A) Isolation

If gas sulfonation equipment and sulfur dioxide

cylinders will be located in a building also used for

other purposes, the sulfur dioxide equipment and

containers shall be located in an isolated room that

shall not contain any chlorination equipment, chlorine

containers or any other equipment unrelated to

sulfonation. Common walls to other areas of the

building shall be gastight. Doors to the room shall

open only to the outside and shall be equipped with

panic hardware. Rooms shall be at ground level and

shall allow easy access to all equipment. Storage areas

should be separated from feed areas; sulfur dioxide and

chlorine cylinders shall be stored in separate areas.

B) Inspection Window

A clear gastight window shall be installed in the

sulfonate room to permits the units to be viewed and

gauges to be read without entering the room.

2) Heat

Sulfonator housing facilities shall be provided with a means

of heating so that cylinder temperatures can be maintained in

the range of 90 to 100 F when sulfur dioxide is to be

withdrawn from the cylinder. The sulfonator room shall be

protected from excessive heat.

3) Ventilation for Sulfur Dioxide Systems

A) Forced, mechanical ventilation that will provide one

complete air change per minute shall be installed in the

sulfonator room. The entrance to the exhaust duct from

the room shall be within 12 inches from the floor and

the point of discharge shall be located so as not to

contaminate the air in the immediate vicinity of the

door to the sulfonator room or ventilation inlet to any

buildings or inhabited areas.

B) The air inlets to the sulfator room shall be located so

as to provide cross ventilation with air and at

temperatures that will not adversely affect the

sulfonation equipment. The vent hose from the

sulfonator shall discharge to the outside atmosphere

above grade.

4) Electrical Controls

Controls for fans and lights shall be located at the

entrances to the sulfonation room and shall automatically

operate when the door is opened and continue in operation

when the operator enters the room and the door is closed.

Provision shall be made for operation of the fans and lights

from the outside without opening the door.

i) Respiratory Protection Equipment

Respiratory protection equipment meeting the requirements of NIOSH

shall be available at all installations where sulfur dioxide gas

is handled and shall be stored in a convenient location outside of

any room where sulfur dioxide is used or stored. The units shall

use compressed air, shall have at least a 30-minute capacity and

shall be the same as or compatible with NIOSH-approved units used

by the local fire department. Instructions for using, testing and

replacing mask parts shall be posted. At large installations,

providing acid suits and fire suits should be considered.

j) Application of Sulfonation Chemicals

1) Contact Period and Reaeration

A minimum contact period of 30 seconds, including mixing

time, at design peak hourly flow or maximum pumpage rate

shall be provided. Mechanical mixers are required unless the

mixing facility will provide the necessary hydraulic

turbulence to assure thorough mixing. A means of reaeration

shall be provided to insure maintenance of the required

dissolved oxygen concentration in the effluent and the

receiving stream after sulfonation. When choosing a

reaeration method the fact that excess sulfur dioxide, formed

when the dechlorinating chemicals are dissolved in water, may

be expected to consume 1 mg of dissolved oxygen for every 4

mg of sulfur dioxide should be taken into account.

2) Sulfonation Dosing Rate Capacity

A) Capacity

Sulfonators shall be designed to have a capacity

adequate to produce an effluent that meets the

applicable chlorine residual effluent limits. Where

necessary to meet the operating ranges, multiple units

shall be provided for adequate peak capacity and to

provide a sufficiently low feed rate on turn down to

avoid depletion of the dissolved oxygen concentrations

in the receiving waters. The sulfonator system shall be

designed on a rational basis and calculations justifying

the equipment sizing and number of units shall be

submitted for the entire operating range, including the

minimum turn down capability for the type of control to

be used. System considerations shall include the

sensitivity and location of the controlling sewage flow

meter, the telemetering equipment and sulfonator

controls.

B) Dosing Rates

The design dosage rate of the sulfonation equipment

shall be based on the particular dechlorinating chemical

used and the applicable residual chlorine limits. The

following theoretical amounts of the commonly used

dechlorinating chemicals may be used for initial

approximations to size feed equipment.

Theoretical mg/l

required to neutralize

1 mg/l Cl[2]

Sulfur dioxide (gas) 0.90

Sodium meta bisulfite

(solution) 1.34

Sodium bisulfite

(solution) 1.46

The design shall take into account the fact that under

good mixing conditions approximately 10% more

dechlorinating chemical than theoretical value is

required for satisfactory results.

C) Liquid Solution Tanks

Mixing and dilution tanks for dechlorinating feed

solutions shall be provided as necessary to mix dry

compounds and to dilute liquid compounds to provide for

proper dosage. Solution tanks should be covered to

minimize evaporation. The mixing and dilution tanks

should be sized to provide sufficient feed solution for

several days of operation. The tanks shall be made of

materials that will withstand the corrosive nature of

the solutions. Refer to Section 370.560.

(Source: Added at 21 Ill. Reg. 12444, effective August 28, 1997)

Because operating data and experience with this process is not well

established, expected performance of the ultraviolet disinfection units

shall be based upon either experience at similar full scale installations

or thoroughly documented prototype testing with the particular wastewater.

Use of this process should be limited to high quality effluent having at

least 65% ultraviolet radiation transmittance at 254 nanometers wave length

and BOD and suspended solids concentrations no greater than 30 mg/l at any

time. Projects will be evaluated by the Agency on the basis of the factors

set out in Section 370.530(b).

(Source: Added at 21 Ill. Reg. 12444, effective August 28, 1997)

(Source: Repealed at 21 Ill. Reg. 12444, effective August 28, 1997)

(Source: Repealed at 21 Ill. Reg. 12444, effective August 28, 1997)

(Source: Repealed at 21 Ill. Reg. 12444, effective August 28, 1997)

(Source: Repealed at 21 Ill. Reg. 12444, effective August 28, 1997)

(Source: Repealed at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Facilities shall be included for collecting samples, as monitoring

requirements warrant, of the disinfected effluent.

b) Where chlorine disinfection is used, equipment shall be provided

for measuring chlorine residual using accepted test procedures.

c) Where required by the Agency, equipment shall also be provided for

measuring fecal coliform using accepted test procedures.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

SUBPART K: TERTIARY FILTRATION

Various types of tertiary filters may be used to polish effluents of

secondary treatment plants.

a) Granular media filtration is considered to include the following

type units:

1) High rate single, dual and multi-media of either the pressure

or gravity type with facilities for backwashing.

2) Low rate sand filters dosed intermittently or periodically.

b) Low rate filtration is generally limited in use to small

installations.

c) For miscellaneous considerations, refer to Section 370.203(j).

a) Design Considerations

Care should be given in the selection of pumping equipment ahead

of filter units to minimize shearing of flow particles.

Consideration should be given in the plant design to providing

flow-equalization facilities to moderate filter influent quality

and quantity.

b) Pretreatment

A positive method shall be provided to control the suspended

solids loading to the filters. Equipment for the feeding of

chemical coagulant aids prior to secondary settling shall be

provided unless other equally effective means of suspended solids

control are used.

c) Multiple Units

Multiple units shall be provided. At least three units should be

provided. Units shall be capable of independent operation and

maintenance.

d) Filtration Rates

The peak hourly flow rate applied to the filter shall not exceed 5

gpm/sq. ft. of filter area, computed with one unit out of service.

1) Rate Controls

Controls shall be provided which allow adjustment and control

of the rate of flow to each filter unit.

2) Flow Measurement

The flow to each filter shall be monitored by indicating

equipment.

e) Accessibility and Maintenance

Each filter unit shall be designed and installed so that there is

ready and convenient access to all components and the media

surface for inspection and maintenance without taking other units

out of service.

f) Housing

Housing of filter units shall be provided. The housing shall be

constructed of suitable corrosion-resistant materials. All

controls shall be enclosed, and the structure housing the filter,

controls and equipment shall be provided with heating and

ventilation adequate to minimize problems with excess humidity.

g) Construction Details

1) Underdrains

The underdrain system shall be designed for uniform

distribution of flow of backwash water (and air, if

provided) without danger of clogging from solids in the

backwash water. A positive means of pressure relief shall

be provided for the underdrain system to prevent structural

damage by excessive backwash pressures. The selection of the

underdrain system shall be based on demonstrated satisfactory

field experience under similar conditions.

2) Media

The selection of proper media sizes and types depends upon

the filtration rate selected, the type of treatment provided

the influent to the filter, filter configuration, and

effluent quality objectives. In dual or multi-media filters,

media size and type selection must consider compatibility

among media. Media shall be selected and provided to meet

specific conditions and treatment requirements relative to

the project under consideration. The selection and sizing of

the media shall be based on demonstrated satisfactory field

experience under similar conditions. All media shall have a

uniformity coefficient of 1.7 or less. The uniformity

coefficient, effective size, depth and type of media shall be

set forth in the specification.

3) Appurtenances

The design of the filter appurtenances shall be based on

demonstrated satisfactory field experience under similar

conditions. The filters shall be equipped with the

following:

A) Wash water troughs.

B) Surface wash, air scouring equipment or mechanical

agitation designed to adequately remove entrapped solids

from the media.

C) Equipment for measuring filter head loss.

D) Filter influent and effluent sampling points.

Also refer to subsections (h)(2), (h)(4) and (i) below.

h) Backwash

1) Rate and Duration

The backwash rate shall be adequate to fluidize and expand

each media layer a minimum of 20 percent based on the media

selected. Minimum and maximum backwash rates shall be based

on demonstrated satisfactory field experience under similar

conditions. The design shall provide for a minimum backwash

period of 10 minutes. Excessive backwash rates may cause

washout of the filter media.

2) Control and Flow Measurement

A positive means of shutting off flow to a filter shall be

provided. Controls shall be provided which permit adjustment

of both the backwash rate and the backwash period. Flow

measurement of the backwash flow rate shall be provided. A

staff gauge or wall mounted scale to allow use of the rise

rate for flow measurement may be used.

3) Clearwell

A clearwell or other plant tankage isolated from unfiltered

flows shall be provided as a source of backwash water.

Filtered plant effluent shall be used as backwash water.

The volume of storage provided shall be sufficient to allow

sequential backwashing of at least 2 filter units at the

design backwash rate.

4) Chlorination of Filter Backwash

Provision shall be made for periodic chlorination of filter

backwash water (or filter influent) to control slime growths.

The flows from the cleaning of the filters shall be returned

to the head of the plant. Refer to subsection (h)(6)(A)

below.

5) Backwash Pumps

Where used, backwash pumps shall be provided in multiple

units, designed for independent operation and maintenance.

Pumps shall be sized in accordance with subsection (h)(1)

above to provide the required backwash rate with one unit out

of service and should be of equal size. The total dynamic

head of the pump shall be limited to that needed for the

application so that undue stress of the underdrain system

will not occur. Refer to subsection (g)(1) above.

6) Mudwell

A mudwell or other plant tankage shall be provided to hold

backwash water from the filters. The volume provided shall

be sufficient to hold the water generated by the backwashing

of two filter units including the water in and above the

filter media prior to filtration. Refer to subsection (h)(1)

above. Filter backwash shall be returned to process or

otherwise treated to insure compliance with applicable

standards.

A) Return Rate

The rate of return of filter backwash to the treatment

units shall not exceed 15 percent of the design average

flow to the treatment units. Refer to subsection (j)(1)

below and Section 370.520(g).

B) Mudwell Return Pumps

Backwash return pumps, where used, shall be provided in

multiple units designed for independent operation and

maintenance. The units shall be sized to provide the

required pumping rate with the largest unit out of

service. Refer to subsection (h)(6)(A) above.

i) Control Panel

Automatic controls shall be provided, with a manual override on

the control panel for operating equipment, including each

individual valve essential to the filter operation.

j) Miscellaneous Considerations

1) Return Backwash Loadings

The return of backwash water and solids will result in

increases in the hydraulic and suspended solids loads to the

preceding treatment units. Design of these units shall take

into account the increased loads.

2) Oil and Grease

Filters at treatment plants treating wastewaters containing

above normal concentrations of greases or similar materials

should be of the gravity type. Facilities should be

considered for the periodic addition of chemicals to remove

greases in such cases.

3) Proprietary Equipment

Proprietary equipment not conforming to the requirements of

this section will be evaluated on a case-by-case basis in

accordance with Section 370.520(b).

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

a) Applicability

1) Intermittent sand filters may be used to polish secondary

effluents. The process removes residual suspended solids and

soluble biochemical oxygen demand and converts ammonia to

nitrate. (See Section 370.1210(b).)

2) Cold weather operational problems may preclude the use of

this process unless the influent temperature to the filter is

adequate to allow efficient filter operation necessary to

meet the applicable effluent standards.

3) Because of manual labor necessary to clean, maintain and

replace sand on the filters, the application is usually

limited to small waste treatment plants.

b) Design Criteria

The criteria of Section 370.940(b), (c), and (f)(3), are generally

applicable to intermittent sand filters used as tertiary

filtration units.

1) Dosing Volumes

The dosing facilities shall be sized to provide for a 12-hour

dosing cycle for each bed.

2) Siphon or Pump Capacity

Siphons (at minimum head) or pumps shall have a discharge

capacity at least 100 percent in excess of the maximum rate

of inflow to the dosing tank, including recirculation, and at

average head, at least 90 gallons per minute per 1,000 square

feet being dosed.

3) Recirculation

Provision for recirculation of filter effluent may be

included to improve process flexibility.

A) Rate

A recirculation rate of up to 100% of design average

flow to the filter may be provided.

B) Variability

Capability for varying the recirculation rate shall be

provided.

4) Loading Rates

The hydraulic load of secondary wastewater applied to

supplemental intermittent sand filters shall not exceed 15

gallons per day (gpd)/sq. ft. More conservative application

rates should be provided for low quality filter influents.

Refer to subsection (d)(3) below.

c) Construction Details

The criteria of Section 370.940(g) are generally applicable to

tertiary intermittent sand filters. Also, refer to subsection

(d).

d) Special Design Considerations in Lagoon Systems

1) General

Low rate sand filter systems that are intermittently or

periodically dosed may be used to reduce suspended solids

from multicell aerated or nonaerated sewage lagoon treatment

plants.

2) Cold Weather Design

Lagoons which have sand filters shall be designed to provide

storage of flows received during cold weather when the filter

is expected to be inoperable.

3) Hydraulic Loading

A) The filter area design considerations must include the

following:

i) The total annual flow volume to be treated (Section

370.520(c)(1)) including wet weather flows if the

lagoons are to be used for wet weather storage.

ii) The effective net days annually for filter

operation excluding cold weather shut-down and

filter maintenance time.

iii) Lagoon effluent quality.

iv) Extent and reliability of flow data from the sewer

system.

B) Where sewer system conditions are not favorable or

industrial waste loadings are expected to increase algae

blooms, the loading rate should be limited to 10

gal./ft.(2)/day.

4) Dosing Considerations

A) Methods of Operation

The design should include allowance for periodic dosing

of varied volumes onto the filter while the filter

discharge is shut off, then to be followed by a

filtration period to completely empty the filter at a

controlled rate.

B) Depth

The filter shall be designed for flexibility of dosing

depth from 6 inches to 2 feet.

C) Valving, Piping, Flow Measurement

i) The filter shall be provided with valving to allow

shutting off and controlling rate of flow both onto

and from the filter. A flow measurement weir or

flume shall be provided both on the inlet and

outlet of the filter for operator control of the

dosing and filtration rates under the falling head

conditions.

ii) The outlet valving, piping and flow measurement

shall be designed to allow complete drainage of the

filter underdrains at the end of the filter cycle

to insure aerobic conditions in the filter during

the rest period.

D) Dosing Inlet Structures

The dosing inlet structures shall be designed to

dissipate inlet velocity and prevent sand scouring

during the dosing period at the high dose rates. The

inlet structures should be arranged to not interfere

with maintenance of the sand surface.

5) Filter Containment Structure

The filter containment may be of vertical concrete walls on

three sides (refer to subsection (d)(6) below) or sloped

earthen berms with impervious lining, constructed to insure

that no ground surface runoff or silts get onto the sand

surface. A freeboard of 1 foot above the maximum design

dosing depth should be provided.

6) Access Ramps

The filter should be designed with a ramp on one end sloped

and surfaced for access to the edge of the bed by wheeled

vehicle to facilitate removing and replacement of sand. For

larger filters, concrete tracks at the level of the sand

surface may be desirable to reduce distance sand must be

handled.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

SUBPART L: NUTRIENT REMOVAL

a) General

1) Method

Addition of lime or the salts of aluminum or iron may be used

for the chemical removal of soluble phosphorus. The

phosphorus reacts with the calcium, aluminum or iron ions to

form insoluble compounds. These insoluble compounds may be

flocculated with or without the addition of a coagulant aid

such as a polyelectrolyte to facilitate separation by

sedimentation.

2) Design Basis

A) Preliminary Testing

Laboratory, pilot or full-scale trial of various

chemical feed systems and treatment processes are

recommended to determine the achievable performance

level, cost-effective design criteria, and ranges of

required chemical dosages.

B) System Flexibility

Systems shall be designed with sufficient flexibility to

allow for several operational adjustments in chemical

feed location, chemical feed rates, and for feeding

alternate chemical compounds.

b) Process Requirements

1) Dosage

The required chemical dosage shall include the amount needed

to react with the phosphorus in the wastewater, the amount

required to drive the chemical reaction to the desired state

of completion, and the amount required due to inefficiencies

in mixing or dispersion. Excessive chemical dosage should be

avoided.

2) Chemical Selection

A) The choice of lime or the salts of aluminum or iron

should be based on the wastewater characteristics and

the economics of the total system.

B) When lime is used it may be necessary to neutralize the

high pH prior to subsequent treatment in secondary

biological systems or prior to discharge in those flow

schemes where lime treatment is the final step in the

treatment process.

3) Chemical Feed Points

Selection of chemical feed points shall include consideration

of the chemicals used in the process, necessary reaction

times between chemical and polyelectrolyte additions, and the

wastewater treatment processes and components utilized.

Considerable flexibility in feed location should be provided,

and multiple feed points are recommended.

4) Flash Mixing

Each chemical must be mixed rapidly and uniformly with the

flow stream. Where separate mixing basins are provided, they

should be equipped with mechanical mixing devices. The

detention period should be at least 30 seconds.

5) Flocculation

The particle size of the precipitate formed by chemical

treatment may be very small. Consideration should be given

in the process design to the addition of synthetic

polyelectrolytes to aid settling. The flocculation equipment

should be adjustable in order to obtain optimum floc growth,

control deposition of solids, and prevent floc destruction.

6) Liquid - Solids Separation

A) The velocity through pipes or conduits from flocculation

basins to settling basins should not exceed 1,5 feet per

second in order to minimize floc destruction. Entrance

works to settling basins should also be designed to

minimize floc shear.

B) Settling basin design shall be accordance with criteria

outlined in Subpart G. For design of the sludge

handling system, special consideration should be given

to the type and volume of sludge generated in the

phosphorus removal process.

7) Filtration

Effluent filtration shall be considered where effluent

phosphorus concentrations of less than 1 mg/1 must be

achieved.

c) Feed Systems

1) Location

A) All liquid chemical mixing and feed installations should

be installed on corrosion-resistant pedestals and

elevated above the highest liquid level anticipated

during emergency conditions. Refer to Section

370.147(b)(2)(A).

B) Lime feed equipment should be located so as to minimize

the length of slurry conduits. All slurry conduits

shall be accessible for cleaning.

2) Liquid Chemical Feed Pumps

A) Liquid chemical feed pumps should be of the positive

displacement type with variable feed rate. Pumps shall

be selected to feed the full range of chemical

quantities required for the phosphorus mass loading

conditions anticipated with the largest unit out of

service.

B) Screens and valves shall be provided on the chemical

feed pump suction lines.

C) An air break or anti-siphon device shall be provided

where the chemical solution stream discharges to the

transport water stream to prevent an induction effect

resulting in overfeed.

D) Consideration shall be given to providing pacing

equipment to optimize chemical feed rates.

3) Dry Chemical Feed System

A) Each dry chemical feeder shall be equipped with a

dissolver which is capable of providing a minimum

5-minute retention at the maximum feed rate.

B) Polyelectrolyte feed installations should be equipped

with two solution vessels and transfer piping for

solution make-up and daily operation.

C) Make-up tanks shall be provided with an eductor funnel

or other appropriate arrangement for wetting the polymer

during the preparation of the stock feed solution.

Adequate mixing should be provided by a large-diameter

low-speed mixer.

d) Storage Facilities

1) Size

Storage facilities shall be sufficient to insure that an

adequate supply of the chemical is available at all times.

Exact size required will depend on size of shipment, length

of delivery time, and process requirements. Storage for a

minimum of a 10-day supply should be provided.

2) Location

A) The liquid chemical storage tanks and tank fill

connections shall be located within a containment

structure having a capacity exceeding the total volume

of all storage vessels. Valves on discharge lines shall

be located adjacent to the storage tank and within the

containment structure.

B) Auxiliary facilities, including pumps and controls,

within the containment area shall be located above the

highest anticipated liquid level. Containment areas

shall be sloped to a sump area and shall not contain

floor drains.

C) Bag storage should be located near the solution make-up

point to avoid unnecessary transportation and

housekeeping problems.

3) Accessories

A) Platforms, stairways, and railings should be provided as

necessary to afford convenient and safe access to all

filling connections, storage tank entries, and measuring

devices.

B) Storage tanks shall have reasonable access provided to

facilitate cleaning.

e) Other Requirements

1) Materials All chemical feed equipment and storage facilities

shall be constructed of materials resistant to chemical

attack by all chemicals normally used for phosphorus

treatment.

2) Temperature, Humidity and Dust Control

Precautions shall be taken to prevent chemical storage tanks

and feed lines from reaching temperatures likely to result in

freezing or chemical crystallization at the concentrations

employed. Enclosure heating or insulation may be required.

Consideration must be given to temperature, humidity and dust

control in all chemical feed room areas.

3) Cleaning

Consideration shall be given to the accessibility of piping.

Piping should be installed with plugged wyes, tees or crosses

at changes in direction to facilitate cleaning.

4) Drains and Drawoff

Above-bottom drawoff from chemical storage or feed tanks

shall be provided to avoid withdrawal of settled solids into

the feed system. A bottom drain shall also be installed for

periodic removal of accumulated settled solids.

f) Hazardous Chemical Handling

The requirements of Section 370.147(b), Hazardous Chemical

Handling, shall be met.

g) Sludge Handling

1) General

Consideration shall be given to the type and additional

capacity of the sludge handling facilities needed when

chemicals are added.

2) Dewatering

Design of dewatering systems should be based, where possible,

on an analysis of the characteristics of the sludge to be

handled. Consideration should be given to the ease of

operation, effect of recycle streams generated, production

rate, moisture content, dewaterability, final disposal, and

operating cost.

a) General

Ammonia control can be accomplished by physical, chemical,

biological and ion-exchange techniques. These criteria contain

design standards for a limited number of biological types and

configurations of ammonia control systems. Other types and

configuration of systems will be evaluated in accordance with

Section 370.520(b).

1) Process Selection

A) Biological systems, normally used to accomplish

secondary levels of treatment, may be adapted to

function as nitrification systems. In applications of

the fixed growth processes staged biological treatment

is normally provided. The single stage activated sludge

process has been found to be reliable for nitrification

and is more commonly used than the two-stage activated

sludge process.

B) Because operating data and experience for the fixed

growth processes for nitrification are not well

established, expected performance in all cases shall be

based upon experience at similar full scale

installations or thoroughly documented prototype testing

with the particular wastewater. The design shall

provide the necessary flexibility to perform

satisfactorily within the range of expected waste

characteristics and temperatures.

2) Alkalinity and pH Control

Biological utilization of ammonia to produce nitrates is

consumptive of available alkalinity in the ratio of 7.14

pounds alkalinity (as CaCO[3]) per pound of ammonia nitrogen

(as N) oxidized. The determination of the need for added

alkalinity must be calculated and included in the basis of

design to be submitted with the plan documents for Agency

approval. The following factors shall be taken into account

in determining the amount of alkalinity to be added:

A) The available alkalinity in the raw wastewater and any

sidestreams;

B) The total ammonia load (including sidestreams such as

flows from digesters and sludge handling facilities)

imposed on the process;

C) The alkalinity needed to maintain pH levels in the range

of 7.2 to 8.4.

3) Load Equalization

Load equalization shall be considered to limit peak loadings

of ammonia from plant sidestreams or slug sources on the

sewer system. For the fixed growth biological nitrification

processes, the ammonia loading peaks shall be limited to 150%

of the design average ammonia loading value.

b) Intermittent Sand Filters

Intermittent sand filters, used in conjunction with various

primary and secondary treatment systems, may be considered for use

as a biological process to convert ammonia to nitrate.

1) Construction Details

The construction details are generally as described in

Section 370.940(g).

2) Loading Criteria

A) Following Primary Treatment

The design loading criteria following primary treatment

is described in Section 370.940(e), (f) and (h) except

that reduced organic loadings should be considered to

insure meeting effluent ammonia limitations.

B) Following Secondary Treatment

The design loading criteria following secondary

treatment is described in Section 370.1130(b)(4) and

(d)(3).

c) Suspended Growth Systems

1) Applicability

Suspended growth nitrifying systems may be designed as a

single stage process with combined carboneous BOD removal and

nitrogenous oxygen demand reductions or as the second stage

of a two-stage process following a first stage activated

sludge process or other types of biological treatment such as

trickling filters.

2) Design Requirements

A) Aeration and Mixing

For nitrification, the oxygen requirement for oxidizing

ammonia must be added to the requirement for

carbonaceous BOD removal. The nitrogen oxygen demand

shall be taken as 4.6 times the peak hourly ammonia (as

N) content of the influent. In addition, the oxygen

demands due to sidestream flows (digestion and sludge

handling facilities and the like) must be considered due

to the high concentrations of BOD and ammonia associated

with such flows. Sufficient aeration and mixing

capability shall be provided to maintain a sludge age of

up to 20 days and a dissolved oxygen concentration in

the aeration tank of at least 2 mg/l.

B) Power

Careful consideration should be given to maximizing

oxygen utilization per unit of power input. Unless flow

equalization is provided, the aeration system should be

designed to match the peak hourly load variation while

economizing on power input.

C) Temperature

Careful consideration shall be given in the design and

selection of aeration and mixing equipment to minimize

heat losses and to maintain sewage temperatures of at

least 50 F in cold weather.

D) Chemical Feed

Where the ratio of ammonia to available alkalinity in

the wastewater requires its use, chemical feed equipment

shall be provided to maintain adequate alkalinity and a

pH level between 7.2 and 8.4.

3) Single Stage Activated Sludge

In addition to the requirements of Section 370.920, the

following criteria shall govern the design:

A) Organic Loading Organic loading shall not exceed 15

lbs/day of BOD[5] per 1,000 cu.ft. of available tank

volume.

B) Detention Time

The hydraulic detention time shall be a minimum of 8

hours based on the plant design average flow as

determined by Section 370.520(c).

4) Activated Sludge Nitrifying Stage Following Secondary

Treatment

The following subsections set out criteria in addition to the

requirements of Section 370.920 for the activated sludge

nitrifying stage following a first stage activated sludge or

fixed growth process used for carbonaceous BOD removal.

A) Organic Loading

BOD[5] concentration shall be limited to 20-50 mg/1.

B) Detention Time

The hydraulic detention time shall be a minimum of 6

hours based on the plant design average flow as

determined by Section 370.520(c).

C) Special Design Requirement

The following requirements in addition to subsection

(c)(3) above, shall be provided:

i) Bypass around the first stage process to allow

discharge of raw or primary settled sewage to the

second stage aeration tank as needed as a carbon

source for control of the nitrification process.

ii) Careful consideration shall be given in the design

and selection of covers and ventilation or aeration

and mixing equipment to minimize heat losses in the

first stage process and maintain sewage

temperatures of at least 50 F in cold weather.

d) Fixed Growth Systems

1) Applicability

Nitrifying fixed growth systems may be used following

activated sludge and fixed growth systems used for

carbonaceous BOD removal.

2) Design Requirements

A) Peak Loadings

In addition to the requirements of Section 370.900, the

design of fixed growth systems shall take into account

the peak hourly ammonia content of the influent. The

design shall provide for ammonia load equalization in

accordance with subsection (a)(3) above.

B) Temperature

Adequate cover or housing of the nitrification units

shall be provided and preceding systems shall be

designed or upgraded to minimize heat losses to maintain

sewage temperatures of at least 50 F in cold weather.

C) Ventilation for Process Air Requirements

Adequate ventilation shall be provided to satisfy the

oxygen demand of the process. Refer to Section

370.900(e)(5).

D) Chemical Feed

Chemical feed equipment shall be provided to maintain

adequate alkalinity concentrations and a pH level

between 7.2 and 8.4 where the ratio of ammonia to

available alkalinity in the wastewater requires its use.

E) Post-Process Settling

Settling tanks following nitrifying fixed growth systems

shall be provided and designed in accordance with

Subpart G. A single unit will be allowed if the

applicable BOD and suspended solids effluent limitations

can be met and other serious operational problems will

not occur when the clarifier is temporarily out of

service.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

Efficiency or Studio Apartment 1

1 Bedroom Apartment 1.5

2 Bedroom Apartment 3

3 Bedroom Apartment 3

Single Family Dwelling 3.5

Mobile Home 2.25

<BSection 370.APPENDIX B Table No. 2 - Commonly Used Quantities of Sewage

Flows From Miscellaneous Type Facilities>>

Gallons Per Person

Per Day

(Unless otherwise

Airports (per passenger) 5

Bathhouses and swimming pools 10

Camps:

Campground with central comfort stations 35

With flush toilets, no showers 25

Construction camps (semi-permanent) 50

Day camps (no meals served) 15

Resort camps (night and day) with

limited plumbing 50

Luxury camps 100

Cottages and small dwellings with

seasonal occupancy 75

Country clubs (per resident member) 100

Country clubs (per non-resident member

present) 25

Dwellings:

Boarding houses 50

(additional for non-resident boarders) 10

Rooming houses 40

Factories (gallons per person, per shift,

exclusive of industrial wastes) 35

Hospitals (per bed space) 250

Hotels with laundry (2 persons

per room) per room 150

Institutions other than hospitals including

Nursing Homes (per bed space) 125

Laundries-self service (gallons per wash) 30

Motels (per bed space) with laundry 50

Picnic parks (toilet wastes only per

park user) 5

Picnic parks with bathouses, showers and

flush toilets (per park user) 10

Restaurants (toilet and kitchen wastes

per patron) 10

Restaurants (kitchen wastes per meal served) 3

Restaurants (additional for bars and cocktail

lounges) 2

Schools:

Boarding 100

Day, without gyms, cafeterias or showers 15

Day, with gyms, cafeterias and showers 25

Day, with cafeterias, but without gyms

or showers 20

Service stations (per vehicle served) 5

Swimming pools and bathouses 10

Theaters:

Movie (per auditorium seat) 5

Drive-in (per car space) 10

Travel trailer parks without individual

water and sewer hook-ups (per space) 50

Travel trailer parks with individual

water and sewer hook-ups (per space) 100

Workers:

Offices, schools and business

establishments (per shift) 15

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

<BSection 370.APPENDIX C Table No. 3 - Air Test Table for Sanitary Sewer

Leakage Testing*>>

SPECIFICATION TIME (MIN:SEC) REQUIRED FOR PRESSURE DROP

FROM 3 1/2 TO 2 1/2 PSIG WHEN TESTING ONE PIPE DIAMETER ONLY

Length of

Sewer Pipe PIPE DIAMETER, INCHES

25 0:04 0:10 0:28 0:28 0:40 1:02 1:29 2:01 2:38

50 0:09 0:20 0:35 0:55 1:19 2:04 2:58 4:03 5:17

75 0:13 0:30 0:53 1:23 1:59 3:06 4:27 6:04 7:55

100 0:18 0:40 1:10 1:50 2:38 4:08 5:56 8:05 10:34

125 0:22 0:50 1:28 2:18 3:18 5:09 7:26 9:55 11:20

150 0:26 0:59 1:46 2:45 3:58 6:11 8:30

175 0:31 1:09 2:03 3:13 4:37 7:05

200 0:35 1:19 2:21 3:40 5:17 12:06

225 0:40 1:29 2:38 4:08 5:40 10:25 13:36

250 0:44 1:39 2:56 4:35 8:31 11:35 15:07

275 0:48 1:49 3:14 4:43 9:21 12:44 16:38

300 0:53 1:59 3:31 10:12 13:53 18:09

350 1:02 2:19 3:47 8:16 11:54 16:12 21:10

400 1:10 2:38 6:03 9:27 13:36 18:31 24:12

450 1:19 2:50 6:48 10:38 15:19 20:50 27:13

500 1:28 5:14 7:34 11:49 17:01 23:09 30:14

*From Standard Specifications for Water and Sewer Main Construction in

Illinois, Fourth Edition, May, 1986. (Copies may be obtained from Illinois

Society of Professional Engineers, Springfield, Illinois 62704.)

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)

<BSection 370.APPENDIX D Figure No. 1 - Design of Sewers - Ratio of Peak

Flow to Daily Average Flow>>

<BSection 370.APPENDIX F Figure No. 3 - B.O.D. Removal Single Stage

Trickling Filter Units Including Post Settling - No Recirculation Included>>

<BSection 370.APPENDIX G Figure No. 4 - Break Tank Sketch for Potable Water

Supply Protection>>

(Source: Repealed at 21 Ill. Reg. 12444, effective August 28, 1997)