1. Section 372.100 Purpose
      2. Section 372.110 Scope and Applicability
      3. Section 372.200 General
      4. Section 372.210 Site Location
      5. Section 372.220 Hydrogeology and Soils
      6. Section 372.230 Buffer Zone
      7. Section 372.240 Loading Factors on Application Fields
      8. Section 372.250 Project Layout
      9. Section 372.300 Equipment Design
      10. Section 372.310 Runoff Control
      11. Section 372.320 Application Area Access Control
      12. Section 372.400 Degree of Treatment Required Relative to Application Area
      13. Section 372.410 Preapplication Treatment Plant Design
      14. Section 372.420 Storage
      15. Section 372.430 Treatment and Storage Area Access Control
      16. Section 372.500 Groundwater Monitoring
      17. Section 372.510 System Flow and Stored Volume Measurement

TITLE 35: ENVIRONMENTAL PROTECTION
                                     
SUBTITLE C: WATER POLLUTION
                                     
CHAPTER II: ENVIRONMENTAL PROTECTION AGENCY
                                     
 
PART 372
ILLINOIS DESIGN STANDARDS FOR SLOW RATE LAND
APPLICATION OF TREATED WASTEWATER
 
                                     
 
SUBPART A: INTRODUCTION
 
Section
372.100 Purpose
372.110 Scope and Applicability
 
SUBPART B: SITE SELECTION CONSIDERATIONS
 
Section
372.200 General
372.210 Site Location
372.220 Hydrogeology and Soils
372.230 Buffer Zone
372.240 Loading Factors on Application Fields
372.250 Project Layout
 
SUBPART C: APPLICATION SYSTEM
 
Section
372.300 Equipment Design
372.310 Runoff Control
372.320 Application Area Access Control
 
SUBPART D: PREAPPLICATION TREATMENT AND STORAGE
 
Section
372.400 Degree of Treatment Required Relative to Application Area
372.410 Preapplication Treatment Plant Design
372.420 Storage
372.430 Treatment and Storage Area Access Control
 
SUBPART E: MONITORING REQUIREMENTS
 
Section
372.500 Groundwater Monitoring
372.510 System Flow and Stored Volume Measurement
 
AUTHORITY: Implementing and authorized by Sections 4(h) and 39(a) of the
Environmental Protection Act [415 ILCS 5/4(h) and 39(a)].
 
SOURCE: Adopted at 19 Ill. Reg. 1297, effective January 31, 1995.
 



Section 372.100 Purpose
 
The purpose of this Part is to establish design standards and permit
application requirements for wastewater treatment systems involving the
non-discharging low-rate application of wastewater to land.
 



Section 372.110 Scope and Applicability
 
a) These design standards apply to non-discharging low-rate land
application of secondary and tertiary treated domestic wastewater
to land upon which crops, turf or trees are grown. These design
standards are to be used in the preparation of all engineering
documents.
b) A preliminary engineering report must be submitted to the Agency
for review and approval prior to the preparation and submission of
plans and specifications or permit applications.
c) Detailed design requirements for treatment, transport and storage
facilities are contained in 35 Ill. Adm. Code 370, Illinois
Recommended Standards for Sewage Works.
 
SUBPART B: SITE SELECTION CONSIDERATIONS
                                     
 



Section 372.200 General
 
The preliminary engineering report required under subsection 372.110(b)
shall address all of the elements contained in this Subpart B, as well as
any of the planning elements of Subparts C through E that are applicable to
the feasibility of the project for which the preliminary engineering report
is submitted.
 



Section 372.210 Site Location
 
a) General
The following factors shall be considered in the selection of the
site:
1) Present and proposed land use regarding residences,
buildings, developments, public access areas, for the site
and adjoining properties;
2) Present and proposed water supply wells;
3) Surface waters and waterways, wetlands and 10-year
floodplains;
4) Subsurface drainage tiles and storm sewers;
5) Abandoned wells and shafts;
6) Buffer zones;
7) Area for expansion of the wastewater treatment and land
application systems;
8) Depth to groundwater;
9) Depth to bedrock; and
10) Topography.
b) Well Setback Requirements
The location of the treatment facilities and land application area
with respect to wells shall be in conformance with the setback
zone requirements of the Illinois Groundwater Protection Act [415
ILCS 55].
c) Topography
1) Cultivated Fields
Slopes on cultivated fields shall be limited to 4% unless
runoff control measures such as berms, collection ditches or
check dams are provided.
2) Sodded Fields and Forested Areas
Slopes on sodded fields and forested areas shall be limited
to 8% unless runoff control measures such as berms,
collection ditches or check dams are provided.
3) Steep Slopes
For slopes steeper than those covered under subsections
(c)(1) and (2) above, the engineering documents shall include
the runoff control measure recommendations of the Soil
Conservation Service (SCS) or county soil conservation
district.
d) Location to Surface Water
Treated wastewater shall not be applied or discharged to wetlands,
streams, waterways or other surface waters. Floodplains which
have a flood return frequency of less than 10 years shall not be
used for land application unless alternate application sites or
additional lagoon storage is provided. Storage shall be designed
in accordance with Section 372.420.
e) Depth to Groundwater
The system design shall be based on rational calculations that
take into account that treated wastewater is not to be applied
when groundwater is within 4 feet of the ground surface. The
design shall include storage capacity for such high groundwater
periods and such periods shall be accounted for in the computation
of the available treated wastewater application days. The design
shall also take into account the effect that the application of
additional water will have on groundwater levels.
f) Depth to Bedrock
For land application of treated wastewater the proposed site shall
have a minimum of 10 feet of earth cover over bedrock, unless the
preapplication treatment system complies with Section 372.400(b).
 



Section 372.220 Hydrogeology and Soils
 
a) General
The engineering documents shall contain information on location,
geology, groundwater, soil characteristics, ground slopes, area
for expansion, and any other factors that will affect the
feasibility and acceptability of the proposed land application
system. Data shall be obtained from available and identified
sources or onsite investigations.
b) Geology
Geological conditions present at the land treatment site and their
potential effects, including depth to bedrock, thickness of
surficial deposits, and the presence of any special conditions
must be described. The major geological factors which shall be
considered are:
1) Structure, weathering and fracturing of bedrock;
2) Lithology;
3) Texture; and
4) Soil profile.
c) Groundwater
The following data and information for the proposed site shall be
provided:
1) Depth to the seasonal high groundwater table and the duration
of seasonal variations;
2) Identification and depth to each aquifer based on Illinois
State Water Survey data or other available well drilling logs
or boring records for the area;
3) Direction of groundwater movement and the location of any
points of groundwater resurfacing;
4) A chemical analysis of the existing groundwater quality for
those parameters set out in Section 372.500(d) which may be
affected by the application of treated wastewater; and
5) An evaluation of the effects of the applied treated
wastewater on groundwater movement and quality.
d) Soil Characteristics
The soil at the proposed site must be evaluated based on on-site
surveys and the most up-to-date published soil survey for:
1) Types and texture classifications;
2) Mantle thickness;
3) Chemical characteristics;
4) pH;
5) Nutrient levels including nitrogen and phosphorus;
6) Cation exchange capacity;
7) Subsurface soil characteristics;
8) Soil borings to a minimum depth of 10 feet; and
9) Permeability of the most impermeable layer of the soil mantle
at each soil boring location.
 



Section 372.230 Buffer Zone
 
a) Non-Spray Surface Application
For non-spray surface application of treated wastewater using
gated pipes, subsurface irrigation, or equivalent methods, the
area wetted by the treated wastewater shall not encroach on any
wetlands, streams, waterways, surface waters, public road rights
of way or residential lot lines.
b) Spray Irrigation
For spray irrigation of treated wastewater, the outer edge of the
area wetted by the spray mist shall not be closer than the
following distances from any residential lot line including
application under design maximum wind conditions with peripheral
spray units operating (refer to Section 370.300 (c)(1)(C)):
1) 200 feet, unless the requirements in (b)(2) or (b)(3) of this
Section are met;
2) 25 feet, if the application area is surrounded by a fence
with a minimum height of 40 inches; or
3) No distance restriction when the application area is:
A) a golf course, if the application occurs only during the
hours between dusk and dawn; or
B) a restricted access area (an area to which public access
is controlled), if the application and its associated
drying time occur during a period when the area is
closed to the public.
The outer edge of the area wetted by spray mist shall not encroach
on any wetlands, streams, waterways or other surface waters or
public road rights of way under design maximum wind conditions.
The engineering document shall provide engineering data for the
spray equipment specified on design pressure, wind velocity,
height of the spray, spray mist drift distances at design
operating pressures and wind velocities with peripheral spray
units operating.
 



Section 372.240 Loading Factors on Application Fields
 
a) General
The size of the application area shall be based on the limiting
characteristic of the treated wastewater and the site. Balances
shall be calculated and submitted for water, nitrogen, phosphorus,
and 5 Day Biochemical Oxygen Demand (BOD[5]). Loading rates must
be established for each parameter. The critical loading rate will
determine the application area required.
b) Water Balance
1) The water balance for the application site shall include the
applied treated wastewater, runon from adjacent areas,
precipitation, evapotranspiration, permeability, groundwater
recharge rate and effect on water table depth and subsurface
tile drainage. The system shall be designed so that runoff
does not occur as a result of treated wastewater application.
Treated wastewater shall not be applied during precipitation
events; however, runoff in response to precipitation is
acceptable. The water balance shall be calculated on a
rational basis for each month and exclude the days on which
application cannot occur due to rainfall, frozen or wet
ground conditions, cropping practices, high groundwater
conditions or wind in excess of design conditions.
2) The design shall provide for alternate wetting and drying
periods in order to maintain aerobic conditions in the
topsoil, as well as to maintain a viable cover crop.
3) The design daily percolation rate shall not exceed 10% of the
minimum soil permeability at the site. The percolation rate
calculations shall exclude the days on which application
cannot occur due to rainfall, frozen or wet ground
conditions, cropping practices, high groundwater conditions
or wind in excess of design conditions.
c) Nitrogen Balance
1) On an annual basis, the total nitrogen applied in the treated
wastewater shall be within agronomic rates and shall be
accounted for by crop uptake, volatilization,
denitrification, adsorption, mineralization and metal
precipitation. Any application of chemical fertilizer must
be accounted for in the design.
2) Land application areas shall be managed according to normal
agricultural and horticultural practices, including but not
limited to cultivated farmland with harvest, fallow land,
set-aside programs, pasture land, golf courses, sod farms,
urban parks, or forest preserves.
 



Section 372.250 Project Layout
 
A single topographic map of the proposed project and the area within 2,500
ft. of the project shall be submitted as a part of the engineering design.
Segmented maps may be provided for large projects. The topographic map
shall show the following information:
a) Application area boundaries including buffer zones;
b) Treatment and storage facilities;
c) Piping and layout of the irrigation system;
d) Present and proposed land use regarding residences, buildings,
developments, public access areas, etc;
e) Present and proposed water supply wells and abandoned wells and
shafts;
f) Direction of groundwater movement and any points of groundwater
resurfacing;
g) Surface waters and waterways, wetlands and 10-year floodplains;
h) Subsurface drainage tiles and storm sewers; and
i) Slopes of the application areas.
 
SUBPART C: APPLICATION SYSTEM
                                     
 



Section 372.300 Equipment Design
 
a) General Requirements
1) The design of all application systems shall provide
facilities to assure uniform distribution of the treated
wastewater over the disposal area.
2) Sufficient spare equipment and parts shall be available to
assure continuity of application during application periods.
3) A single irrigation pumping unit may be utilized if a spare
pump in working condition is available in dry storage.
4) The design shall provide for draining all pipes and equipment
to prevent freeze damage.
b) Non-Spray Surface Application Systems
Non-spray surface application systems which provide for even
distribution of wastewater effluent on the land site may be
utilized, including ridge and furrow, gated pipe, or equivalent
systems. These systems may be mobile or fixed on the site. They
shall be designed to minimize clogging and to allow for ease of
maintenance.
c) Spray Irrigation Systems
1) Spray Equipment
A) Fixed head systems and center pivot rigs may be
utilized. A permanent connection point must be provided
for each setting of moveable spray irrigation equipment.
The design shall include provisions for shutting off the
peripheral spray heads to prevent drift of spray beyond
the application area under design wind conditions.
B) The irrigation system controls shall be simple and be
protected from lightning damage.
C) The design maximum wind velocities shall be 15 MPH in
urban and residential areas and 25 MPH in agricultural
areas.
2) Nozzle Pressure Regulation
Regulation of nozzle pressure to compensate for field
elevations and line losses shall be provided.
 



Section 372.310 Runoff Control
 
The design shall provide for control of the application intensity to
prevent runoff in response to treated wastewater application on all parts
of the application field. In order to minimize runoff during precipitation
events, the exclusion of runon from adjacent areas shall be considered.
 



Section 372.320 Application Area Access Control
 
The entire application area and buffer area shall be posted at 100 yard
intervals around the perimeter identifying the area as a "Treated
Wastewater Application Area". The application area shall be fenced to
prevent access by children and unauthorized personnel unless the
pretreatment provided meets the urban area pretreatment requirements of
Section 372.400(b) or the land application system is located in an
agricultural area or a forested area that does not have general public
access.
 
SUBPART D: PREAPPLICATION TREATMENT AND STORAGE
                                     
 



Section 372.400 Degree of Treatment Required Relative to Application Area
 
a) Agricultural Areas
Agricultural or forested areas that do not have public access
shall provide at a minimum a two cell lagoon system or a
mechanical secondary treatment facility.
b) Urban Areas
Urban parks, forest preserves and golf courses and other areas
with public access shall utilize as a minimum a two cell lagoon
system with tertiary sand filtration and disinfection or a
mechanical secondary treatment facility with disinfection.
 



Section 372.410 Preapplication Treatment Plant Design
 
a) Design and Construction Requirements
All preapplication treatment systems shall be designed and
constructed in accordance with 35 Ill. Adm. Code 370, Illinois
Recommended Standards for Sewage Works.
b) Screening
All treatment systems except those requiring tertiary filtration
must have a screening device sized to minimize plugging of the
spray nozzles following the storage lagoon prior to the irrigation
distribution system.
 



Section 372.420 Storage
 
a) Storage Volume
All land application systems must provide adequate storage, with
adequacy being determined using either of the following methods,
except that those facilities that do not generate wastewater year
round must use Method I:
1) Method I
Adequate storage shall be based on a rational design that
must include capacity for the wettest year with a 20-year
return frequency. The volume provided shall be sufficient to
hold flows received during the following periods:
A) When the soil is frozen, including subsoil frost layers;
B) When there is an ice or snow cover on the ground;
C) When the soil temperature at 4" depth is less than 40  F
or the mean air temperature is less than 35  F;
D) When the ground is saturated or there is standing water
(as from late winter snowmelt or spring rains);
E) When the groundwater table is within 4 feet of the
surface;
F) During days when precipitation exceeds 0.1 inch;
G) During agricultural and horticultural practices;
H) During days set aside for equipment maintenance;
I) During days when the design maximum wind velocity is
exceeded; and
J) When the soil is barren, except for seeded areas, areas
with growing crops, or areas with a trashy cover to
prevent erosion.
2) Method II
The minimum storage capacity, by volume, shall be capable of
storing at least 150 days production of wastewater, at design
average flow, except that in southern Illinois areas (defined
as all areas south of Interstate 70) a minimum of 120 days
storage capacity shall be provided.
b) Design and Construction Requirements
The storage lagoon must be designed and constructed in accordance
with 35 Ill. Adm. Code 370, Illinois Recommended Standards for
Sewage Works.



Section 372.430 Treatment and Storage Area Access Control
 
The entire treatment and storage lagoon area shall be enclosed with fencing
to preclude livestock and prevent access by the general public. Warning
signs shall be posted at 100-yard intervals on exterior fences designating
the area as a "Wastewater Treatment Facility". A vehicle access gate of
sufficient width to accommodate mowing equipment and maintenance vehicles
shall be provided. All access gates shall be provided with locks.
 
SUBPART E: MONITORING REQUIREMENTS
                                     
 



Section 372.500 Groundwater Monitoring
 
a) General
1) Saturated zone groundwater monitoring shall be provided for
all land application systems. A minimum of three groundwater
monitoring wells must be provided, one upgradient for
determining background concentrations and two downgradient in
the dominant direction of groundwater movement from the land
application system.
2) Provision shall be made for sampling of the discharge from
any drainage tiles underlying the application area.
b) Potable Water Supply Wells
Where the project site is within 1,000 feet of existing potable
water wells but the wells are outside the minimum setback zone of
the Illinois Groundwater Protection Act [415 ILCS 55], groundwater
monitoring wells must be provided between each potable water well
and the land application system.
c) Monitoring Well Design
The monitoring wells shall be constructed with provisions for
sampling at the surface of the water table and at 5 feet below the
water table at each monitoring site.
d) Testing and Monitoring Equipment
Provision shall be made for testing groundwater for nitrates,
ammonia nitrogen, chlorides, sulfates, pH, total dissolved solids,
phosphate, and coliform bacteria as specified by the Agency permit
for the project to measure compliance with groundwater standards.
Testing shall be performed in accordance with 40 CFR 136 (1992)
(no later amendments or editions), and may be done either at an
onsite laboratory or through a contractual arrangement with an
offsite laboratory.
 



Section 372.510 System Flow and Stored Volume Measurement
 
a) System Flows
Plant influent and effluent irrigation flow measurement shall be
provided. Flow measurement shall not be less than elapsed time
meters used in conjunction with pumping rate tests or calibrated
weirs. All flow measurement equipment shall be sized to function
effectively in the full range of flows expected and shall be
protected against freezing.
b) Stored Volume Measurement
A staff gauge shall be provided in the storage lagoon located near
the draw-off structure and must be easily read from the lagoon
dike.
c) Monitoring Systems
Monitoring equipment for wastewater application sites shall
include equipment for measuring air temperature, soil temperature,
precipitation, wind speed and direction, and depth to groundwater.
         
 

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