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Metropolitan Water Reclamation District of Greater Chicago

IEPA ATTACHMENT NO.t....Q.

BOARD OF COMMISSIONERS

Terrence J. O'Brien'

President

Kathleen Therese Meany

Vice President

Gloria Alin° Majewski

100 EAST ERIE STREET?

CHICAGO, ILLINOIS 60611-3154?

Mr. Toby Frevert, Manager

Division of Water Pollution Control

Bureau of Water

Illinois Environmental Protection Agency

1021 North Grand Avenue East

P.O. Box 19276

Springfield, Illinois 62794-9276

Dear Mr. Frevert:

Subject: Evaluation of Management Alternatives for the Chicago Area

Waterways: Investigation of Technologies for Supplemental

Aeration of the North and South Branches of the Chicago River,

Flow

Augmentation of the Upper North Shore Channel, and Flow

Augmentation and Supplemental Aeration of the South Fork of the

South Branch of the Chicago River

The Metropolitan Water Reclamation District of Greater Chicago, at the

request of the Illinois Environmental Protection Agency (IEPA), hereby

submits the enclosed, reports entitled "Technical Memorandum 4WQ:

Supplemental Aeration of the North and South Branches of the Chicago

River", "Technical Memorandum SWQ: Flow Augmentation of the Upper North

Shore Channel", and "Technical Memorandum 6WQ: Flow Augmentation and

Supplemental Aeration of the South Fork of the South Branch of the

Chicago River."

Using the services of Consoer Townsend Envirodyne Engineers, Inc., these

reports have been developed to evaluate technologies and costs for

Supplemental Aeration of the North and South Branches of the Chicago

River, Flow Augmentation of the Upper North Shore Channel, and Flow

Augmentation and Supplemental Aeration of the South Fork of the South

Branch of the Chicago River.

If you have any questions, please contact Mr. Lou Kollias at (312) 751-

5190.

Very truly yours,

VNI--

Richard Lanyon U

General Superintendent

TECHNICAL MEMORANDUM 4WQ

SUPPLEMENTAL AERATION OF THE NORTH AND

SOUTH BRANCHES OF THE CHICAGO RIVER

METROPOLITAN WATER RECLAMATION DISTRICT OF

GREATER CHICAGO

NORTH SIDE WATER RECLAMATION PLANT AND SURROUNDING

CHICAGO WATERWAYS

Submitted by:

CTE AECOM

Revision 4 – January 12, 2007

MWRDGC Project No. 04-014-2P

CTE Project No. 40779

FINAL 01/12/07

TABLE OF CONTENTS

Objective and Scope of Study

4-2

Waterway Target Dissolved Oxygen Standards

4-4

Chronology of Past Supplemental Aeration Studies

4-4

Waterway Modeling of Supplemental Aeration

4-6

Supplemental Aeration Modeling Runs

4-6

LONG LIST OF TECHNOLOGIES

4-10

EVALUATION ?

4-21

Advantages and Disadvantages of Technologies

4-21

Air Diffusion Systems

4-21

Head Loss Structures

4-22

Mechanical Surface Aerators

4-23

U-Tube Aerator Systems

4-23

High Purity Oxygen Systems

4-23

Screw Pumps

4-24

Scoring of Qualitative Economic and Non-Economic Criteria Matrix ...

Short List of Technologies

4-31

4-i

FINAL 01/12/07

Land Availability for Supplemental Aeration

4-31

Cost of Supplemental Aeration Stations

4-38

SUMMARY, CONCLUSIONS AND RECOMMENDATIONS

4-39

FINAL 01/12/07

LIST OF TABLES

Table 4.1?

Air Diffusion Systems – Advantages and Disadvantages

4-22

Table 4.2?

Head Loss Structures – Advantages and Disadvantages

4-22

Table 4.3?

Mechanical Surface Aerators–Advantages and

Disadvantages

4-23

Table 4.4?

Compressed Air U-Tube Contactors – Advantages and

Disadvantages

4-23

Table 4.5?

High Purity Oxygen – Advantages and Disadvantages

4.7?

Summary of Capital and Annual Costs

4-39

FINAL 01/12/07

LIST OF FIGURES

Figure 4.1

The Chicago Area Waterways

4-3

Figure 4.2

Supplemental Aeration of North and South Branches of Chicago

River Percent of Hours Complying with 5 mg/I Criterion,

All Time Periods

4-8

Figure 4.3

Proposed Aeration Station Sites

4-9

Figure 4.4

Schematic Diagram of Devon Avenue Instream

Aeration Station

4-12

Figure 4.5

Schematic of Jet Aeration System

4-13

Figure 4.6?

Schematic of 3-Step Free Fall Weir Supplemental

Aeration System

4-14

Figure 4.7?

Mechanical Surface Aerator

4-16

Figure

4.8?

Schematic of Compressed Air U-Tube Contactor

4-17

Figure 4.9

Schematic of Pressurized HPO Contactor

4-19

Figure 4.10 Barge Mounted HPO Diffuser System

4-20

Figure 4.11 80 g/s (Oxygen) SEPA Station Conceptual Layout

4-33

Figure 4.12 80 g/s (Oxygen) Jet Aeration Station Conceptual Layout

4-35

Figure 4.13 80 g/s (Oxygen) Ceramic Fine Bubble Diffuser Station

Conceptual Design

4-36

Figure 4.14 80 g/s (Oxygen) Compressed Air U-Tube Station Conceptual

Design

4-37

FINAL 01/12/07

APPENDICES

Appendix A Unit Costs Used in Cost Estimates

Appendix B Detailed Capital Cost Estimates for Four Short-Listed Technologies

Table B-1 through B-5

Appendix C Detailed Annual Cost Estimates for Four Short-Listed Technologies

Table C-1 through C-8

Appendix D Figures Showing Land Availability for Four Supplemental Aeration

Stations

Figures D1 through D4

FINAL 01/12/07

SUPPLEMENTAL AERATION OF THE NORTH AND

SOUTH BRANCHES OF THE CHICAGO RIVER

(TM-4WQ)

INTRODUCTION

Background

Consoer Townsend Envirodyne Engineers, Inc. (CTE) was retained in 2005 by the Metropolitan

Water Reclamation District of Greater Chicago (MWRDGC) to provide engineering services to

prepare a comprehensive Infrastructure and Process Needs. Feasibility Study (Feasibility Study)

for the North Side Water Reclamation Plant (WRP). As part of the scope of work for the

Feasibility Study, CTE was directed to determine the technologies and costs of water quality

management options which originated from the on-going Use Attainability Analysis (UAA) being

conducted by the Illinois Environmental Protection Agency (IEPA) of the Chicago Area

Waterways (CAWs). The CAWs are shown in Figure 4.1.

This report presents the results of a

study of one of the water quality management options that

originated from the UAA, namely supplemental aeration of the North and South Branches of the

Chicago River (NBCR and SBCR, respectively). The principal objective for this supplemental

aeration study is to improve the dissolved oxygen concentrations in the NBCR and SBCR.

Supplemental aeration of the NBCR and SBCR is among several water quality management

options studied by CTE. Other water quality management options are discussed in separate

reports. These reports are not designed to determine which (if any) of the water quality

management options should be implemented. Such a determination can only be made by

conducting a comparison of the costs and benefits of all the management options and then

developing a water quality management plan which combines the most cost effective option into

an integrated strategy for improving water quality of the CAWs. Such an integrated study has

not been developed at this time.

UAA Process

The Clean Water Act requires the states to periodically review the uses of waterways to

determine if changes to the existing water quality standards are needed to support a change in

use. Based upon a study of the CAWs, the IEPA had decided that a change may be required in

the dissolved oxygen (DO) standards for these waterways.

As part of the UAA the IEPA suggested several water quality management options for improving

the DO of the CAWs and asked that the MWRDGC determine the technologies and costs for

these options. One of the options that was suggested by the IEPA was supplemental aeration

of NBCR and SBCR.

FINAL 01/12/07

Supplemental Aeration

Supplemental aeration is a water quality management option which has the potential for

improving the DO of NBCR and SBCR. This option was studied in this report.

Supplemental aeration is already being practiced in the CAWs by the MWRDGC. Two

supplemental aeration stations exist on the North Shore Cannel (NSC) and the North Branch of

the Chicago River (NBCR) at Devon and Webster Avenues, respectively. These stations

provide aeration by means of porous ceramic diffusers at the bottom of the waterway. The

diffusers are supplied with air from an on-shore blower facility at each station. Along the Little

Calumet River, Calumet River and Cal-Sag Channel waterways, the MWRDGC has five

supplemental aeration stations utilizing sidestream aeration where low lift pumps remove a

portion of the flow from the waterway and aerate this flow using a free-fall weir system which

subsequently returns the flow back to the waterway.

Objective and Scope of Study

As noted above, the IEPA requested that the MWRDGC study the potential technologies,

opinion of probable costs and impacts for supplemental aeration of the NBCR and SBCR. The

objective of this study was to determine the potential supplemental aeration technologies and

opinion of probable costs to achieve possible future regulatory dissolved oxygen (DO) levels for

these waterways.

CTE developed a long list of supplemental aeration alternatives. Using an evaluation matrix

based upon criteria fromTM-1 and input from the MWRDGC, CTE then prepared a short list of

potential supplemental aeration alternative technologies.

Based upon simulation runs using the Marquette University model, the aeration capacity and

location of supplemental aeration stations needed to supplement the dissolved oxygen in the

NBCR and the SBCR was determined. For each short listed alternative, CTE then prepared a

conceptual layout and cost estimate for the aeration stations determined from the Marquette

Model.

The MWRDGC did not intend this study to reach a conclusion regarding the best supplemental

aeration technology for implementation or to provide design criteria of a supplemental aeration

system for the NBCR and SBCR. Therefore, CTE prepared a short list of potential technologies

and estimated the costs to illustrate the potential range of expenditures for supplemental

aeration of the SBCR and NBCR. The cost estimates are planning level opinion of probable

costs with a potential variation of + 30 percent.

This study also was not intended to reach a conclusion as to whether supplemental aeration of

the NBCR and SBCR should be implemented. Such a decision should be reached only after

integrated study of all IEPA requested water quality management options is conducted. This

study would determine the relative costs and benefits of these options and then determine their

priority for potential implementation. Such an integrated study is beyond the scope of this

Technical Memorandum.

LAKE MICHIGAN

rat

----\---Addison Street

•,04atefv.w:

Division Street Avenue

Kik

gpr

FINAL 01/12/07

Figure 4.1 — The Chicago Area Waterways

FINAL 01/12/07

Waterway Target Dissolved Oxygen Standards

The IEPA has not yet made a decision as to the dissolved oxygen standards for the NBCR and

SBCR. However for the purposes of this supplemental aeration study of the NBCR and SBCR,

it was necessary to assume a target dissolved oxygen standard.

After discussions with the MWRDGC, it was concluded that the target dissolved oxygen water

quality standard would be 5 mg/I. Because of the highly variable nature of the NBCR and SBCR

due to wet weather flows, etc., it was decided that 90% compliance with the 5 mg/I standard

would be reasonable. Thus, this is the regulatory target used to determine the size and location

of supplemental aeration of the NBCR and SCBR. The model was used to locate and size the

station needed in addition to the existing MWRDGC station at Devon and Webster Avenues.

It should be stated here that the DO regulatory target should not be considered to be a

recommendation of the MWRDGC for the NBCR and SBCR. This target was chosen because it

is necessary to have a target hi order to determine the size and location of supplemental

aeration stations on the SBCR and NBCR. It may well be that a lower standard will be

protective of the SBCR and NBCR. It is hoped however that the IEPA will recognize that it is

virtually impossible to meet a standard 100 percent of the time. Thus a standard which requires

less than 100% compliance should be considered in the UAA process as was done in this

report.

Chronology of Past Supplemental Aeration Studies

The MWRDGC has been at the forefront of the development and the implementation of

innovative concepts to improve wastewater treatment and instream water quality since its

inception over a hundred years ago. Consequently, not surprisingly, it has been a leader in

developing systems and methods for improving instream dissolved oxygen levels via

supplemental aeration. During 1914, the MWRDGC studied the feasibility of aerating a portion

of the Sanitary and Ship Canal (SSC) flow in galvanized steel tanks and returning it to the

waterway. The objective was to determine if the oxygen returned to the canal satisfied an

equivalent amount of dissolved biochemical oxygen demand (BOD). The results were

inconclusive.

In 1921, a small-scale study was performed by the MWRDGC where Chicago River water was

aerated in 100 gallon vitrified tile tanks, indicating that the stream BOD could be satisfied when

DO levels near saturation were achieved. Continuing along these experimental lines, tests were

conducted by the MWRDGC during. 1923 in a wooden tank using air blowers and bottom

diffusers. The results of this pilot study were positive. This led to a full-scale instream study.

During 1924, an old boat lock (137 feet by 22 feet) at the Lockport power dam was deemed

equivalent to a full-scale channel section of water and appropriate for use. Studies considering

the effects of water temperature, aeration times, and types and combination of diffuser plates on

dissolved oxygen uptake rates were conducted.

The interest in developing techniques and/or methodologies, for achieving supplemental

instream aeration by the MWRDGC was reborn in the mid 1950s. During this time, an

engineering study was conducted to determine the feasibility of using hydro-turbine aeration

(turbine venting) at the Lockport power dam to supply DO to the depleted DO in the waters

upstream of the dam as these waters pass through the penstocks and turbines. A conclusion

was reached that it was not economically feasible to do so because compressed air would be

needed to entrain air into the draft tubes below the turbine runners.

4-4

FINAL 01/12/07

However, in lieu of the less than encouraging results of the turbine venting evaluations

conducted in the mid 1950s, other instream aeration methods were considered for use for

supplementing the DO in the waters immediately above Lockport. A 1958 report published by

the MWRDGC considered using diffused air distributed by porous plates laid on the bottom of

the Sanitary and Ship Canal.

A full-scale, instream study was conducted by the MWRDGC in 1963 using two commercially

available surface mechanical aerators. The aerators were placed in the forebay above the

Lockport dam. The aerators added significant DO poundage to the canal water, but the

conclusions were ambiguous as evidenced by the following quote from the report:

"Engineering studies as to optimum staging of aerators in a waterway system to

cope with existing pollution loads would be of value in comparing costs for

different techniques of aeration."

During the 1960s and 1970s, the United States Environmental Protection Agency (USEPA) (or

precursors) discouraged the use of supplementing instream DO via artificial methods. On April

5, 1977 the General Counsel for the USEPA ruled on a request from the Deputy Assistant

Administrator for Water Enforcement entitled "Use of In-stream Mechanical Aerator to Meet

Water Quality Standards". This ruling was adamantly against supplemental aeration as quoted

below:

"In-stream aerators should not be recognized as being analogous to low flow

augmentation. Therefore, the Office of Enforcement recommends that the use of

these aerators as means of achieving water quality standards following Best

Available Treatment (BAT) be denied."

However, the State of Illinois viewed the situation quite differently. On August 29, 1972, the

Illinois Pollution Control Board (IPCB) acted upon a three part petition submitted by the

MWRDGC on May 3, 1972. Part III requested approval to install instream aerators in the North

Shore Channel and North Branch of the Chicago River waterways. The board ruled favorably

(by a 5-0 vote) as follows:

"The MWRDGC's statement mentions its Board of Trustees action of April 29,

1972 authorizing a $1,500,000 instream aeration system for the North Shore

Channel to be operative by April 1, 1974

Instream aeration has been shown to

be perhaps three to five times cheaper than higher treatment....and can be

installed quickly

We urge the instream aeration system be completed as soon

as possible."

Consequently, to maintain-stream DO levels at or above applicable standards, the MWRDGC

adopted an instream aeration implementation program in 1975. This led to the installation of the

diffused air system at Devon Avenue, which started operation on February 8, 1979, and at

Webster Avenue, which started operating, on June 6, 1980. They have been operating on a

seasonal basis since.

The MWRDGC also concluded that DO supplementation was needed on the Cal-Sag

Channel/Little Calumet River/Calumet River waterway system. The possible use of methods

other than diffused aeration for supplementing DO along the length of the Cal-Sag waterway

system was explored. One methodology that was considered was the use of side channel weirs

4-5

FINAL 01/12/07

to aerate a portion of the total flow and return it to the main channel. During the summer of

1987 an in-depth weir aeration study was undertaken by the MWRDGC using a full scale pilot

plant located on the banks of the Sanitary and Ship Canal. The experimental results indicated

that water falling freely over stepped weirs produced excellent aeration. Consequently, the

decision was made to install five side stream weir aeration stations along the Cal-Sag waterway

system. The stations are now referred to as SEPA (Sidestream Elevated Pool Aeration) stations

and have provided oxygen supplementation since they went on-line during 1992 and 1993.

Waterway Modeling of Supplemental Aeration

The MWRDGC retained Marquette University to develop a simulation model of the Chicago

Area Waterways including the NBCR and SBCR. This model is described in the report entitled,

"Preliminary Calibration of a Model for Simulation of Water Quality During Unsteady Flow in the

Chicago Waterway System and Proposed Application to Proposed Changes to Navigation

make-Up Diversion Procedures," dated August, 2004. This report was produced by Dr. Charles

Melching from the Institute for Urban Environmental Risk Management at Marquette University

(Milwaukee, Wisconsin).

The Marquette Model was used to determine the aeration capacity and location of supplemental

aeration stations on the NBCR and SBCR. Marquette University conducted various simulation

runs to determine the aeration capacity and location

supplemental aeration stations sufficient

to achieve 5 mg/I of dissolved oxygen, 90% of the time in the NBCR and SBCR. Percent

compliance was determined over all time periods simulated in the Marquette Model.

These time periods were:

Year

Time Period

2001? July 12 to September 14

2001? September 1 to November 10

2002?

May 1 to August 11

2002? August 10 to September 23

Model simulations in the Marquette Model include overlapping times periods. It is inappropriate

to use overlapping time periods for the evaluation of water quality management options.

Therefore, percent compliance in this report does not include overlapping periods. For this

report, all the results for the July 12 to September 14, 2001 and May 1 to August 11, 2002 times

periods were used, those parts

the time periods of September 1 to November 10, 2001 and

August 10 to September 23, 2002 which overlapped with these periods were not used.

For each location in the NBCR and SBCR simulated in the Marquette Model, the percent

compliance was calculated based upon the total number of hours out

all time periods that the

hourly dissolved oxygen was at or above 5 mg/I. The percent compliance was based upon the

new stations needed to be added to augment the existing aeration stations at Devon Avenue

and Webster Avenue.

The various modeling runs conducted by Marquette University were based upon discussions

between CTE and University staff prior to the runs. The location and sizing of aeration stations

on the NBCR and SBCR based upon these modeling runs were discussed at a workshop held

with the MWRDGC. The final selected location and sizing of the aeration stations described in

this report represent the results of this workshop

4-6

FINAL 01/12/07

Supplemental Aeration Modeling Runs

The Marquette Model was used to determine the aeration capacity and location of supplemental

aeration stations on the NBCR and SBCR. For these modeling runs, the following conditions

were assumed.

Tunnel and Reservoir (TARP) Tunnels are fully operational

TARP Reservoirs are not on-line.

Other IEPA Requested Water Quality Management Options are not on-line.

The existing Devon and Webster in-stream aeration stations are fully operational

with three blowers assumed to be in service.

Various model simulation runs were conducted. After discussions between Marquette

University, CTE and the MWRDGC, it was agreed that the following supplemental aeration

station locations and aeration capacities represent a reasonable scenario for conceptual cost

estimation.

Waterways

Location (Cross Street)

Required Oxygen Delivery

Capacity

NBCR

Diversey Avenue

30 g/s (5,700/lbs/day)

30 g/s (5,700 lbs/day)

80 g/s (15,200 lbs/day)

It should be noted that the 18th

Street Station on the SBCR was originally shown by the

Marquette Model to be located about 1 mile further upstream. But land availability was lacking

at the upstream site. Subsequent model runs showed that the 18th

street location achieved the

water quality target using the same oxygen capacity (5,700 lbs/day) as found necessary for the

upstream site.

This set of supplemental aeration stations achieves a 5 mg/I water quality standard 90 percent

of the time for both the NBCR and SBCR. Figure 4.2 is a graph illustrating the percent

compliance for this set of supplemental aeration stations from the outfall of the North Side WRP

to the junction of the SBCR and the South Fork of the South Branch of the Chicago River

(Bubbly Creek). As shown in Figure 4.2, the percent compliance was calculated for all time

periods simulated in the Marquette Model.

Figure 4.3 shows a map of the Chicago Area Waterways with the locations of the four

supplemental aeration stations as determined by the Marquette model. Also shown in Figure 4.3

are the existing MWRDGC aeration stations at Devon and Webster Avenues.

4 New Aeration Stations

Baseline Condition

46 45 44 43 42

41 40 39 38 37 36 36 34 33 32 31 30

River Mile

Figure 4.2 – Supplemental Aeration of North and South Branches of Chicago River, Percent of Hours Complying with 5 mg/I

Criterion, All Time Periods

4-8

••••••:v••••-•

•.•?...•?.•••......?•• ..?....?

ts'4-•••••••i•CtY...:t t'JS

.. • .. • .. : ••:.• • !

FINAL 01/12/07

Figure 4.3 – Proposed Aeration Station Sites

4-9

FINAL 01/12/07

LONG LIST OF TECHNOLOGIES

Over the past 25 to 30 years, significant advances in supplemental aeration technologies have

been made. Many experts place supplemental aeration methods or procedures into two

categories, namely, aeration and oxygenation.

Aeration is defined as using atmosphere air as the oxygen source; whereas, oxygenation is

defined as using manufactured oxygen gas as the source. Each of the two categories has many

divisions and subdivisions some of which are common to each except for the fact that the

sources of oxygen differ.

The acquiescence by regulatory agencies, starting in the late 1970s, in the use of supplemental

aeration as a means of improving stream water has led to supplemental aeration equipment and

methodologies to be developed and marketed. The object of this section is to explore the

possibilities that are currently available for potential use in solving the DO situations that occur

in the study area.

The range of options available for supplemental aeration technologies is listed below:

I. Pressurized Air Diffusers

Porous Ceramic Diffusers

Membrane Diffusers

Jet Ejectors

II. Head Loss Structures

A. Free Fall Weirs

B. Cascades

III. Mechanical Aerators

IV. U-Tube Bubble Contactors

A. Compressed Air Injection

V. Vaporized High Purity Liquid Oxygen (HPO)

A. Pressurized Water Injection with Diffusers

B. U-Tube Bubble Contactor

Mobile (Barge-Mounted) Dispersion

VI. Screw Pump Aeration

A brief description and discussion of each long list technology will be presented below.

In the sections below, oxygen transfer efficiency (OTE) is defined as the amount of oxygen

actually transferred from the gas phase to the liquid phase as a percentage of the oxygen

supplied in the gas phase.

Pressurized Air Diffusers:

Many instream aeration systems use atmospheric

oxygen supplied by blowers located on shore with the air distributed via instream

diffusers. One major design concern is selecting the proper diffuser system to

4-10

FINAL 01/12/07

meet instream DO needs while being reasonably compatible with the physical

characteristics of a stream.

Fine Bubble Porous Ceramic Diffusers. The MWRDGC's Devon and

Webster Street instream aeration stations consist of blower-induced air

distributed to porous ceramic plates located on the bottom of the North

Branch of the Chicago River as shown in Figure 4.4. The stations have

been operating continuously for about 25 years; however, both have

experienced operation and maintenance problems. Typically these fine

bubble diffuser air systems have an OTE of 10-30 percent.

Membrane Diffusers: Membrane diffuser systems are generally very

flexible and resist fouling due to the following characteristics:

•

The membranes are normally closed until sufficient air pressure

opens the units to begin operation.

•

When the air is interrupted,

the membranes close preventing

liquid/solids entry.

•

Membrane diffusers have only an exterior surface phenomena as the

liquid and air interface is at the exterior surface of the membrane

compared to the interior of a ceramic rigid media material.

•

Operation of a membrane unit involves major flexing during on/off

operation with major flexing even during normal airflows. This flexing

tends to minimize the accumulation of surface inorganic materials.

Figure 4.4 — Schematic Diagram

of Devon Avenue Instream Aeration Station

FINAL 01/12/07

•

The surface of some membrane materials is quite smooth and

slick. These smooth, slick surfaces minimize or eliminate calcium

carbonate and other contaminant build-up.

•

Typically membrane diffusers have a OTE of 10-30 percent.

Jet Ejectors.

Jet ejectors mix air and water together using a venturi and

provide a jet of water containing air bubbles. This jet of water creates

good horizontal movement of water over a defined radius or area. Figure

4.5 shows a typical arrangement for a jet aeration system that would

apply to waterway aeration.

The horizontal travel of the plume maintains a gas/liquid transfer interface

for a much longer period of time than conventional diffused aeration

systems. The horizontally mixed plume is enriched with fine bubbles

which will rise slowly to the surface providing for excellent oxygen

absorption. All mixing occurs below the surface eliminating mist and/or

spray problems.

Typically, jet aerators have OTE of 10-25 percent.

Figure 4.5 – Schematic of Jet Aeration System

4-13

FINAL 01/12/07

II.

Head Loss Structure.

Head loss structures within the stream or waterway

can result in aeration. The net gain in DO at the structure depends upon the

geometry of the structure versus conditions upstream. Aeration from head loss

structures is usually expressed by an equation relating the DO downstream of

the structure to the DO upstream, saturation DO and a dam aeration

coefficient which is dependent upon the type of head loss structure. The dam

aeration coefficient is expressed per unit length of the structure. Structures with

higher coefficients have higher aeration efficiencies.

A. Free-Fall Weirs.

Sharp-crested, free-fall weirs have clearly been shown to be

excellent aeration devices. Step weirs are a series of free-fall weirs with

each free-fall discharging into a deep pool. Step weir installations can be

used to supplement instream DO, but they must be built on sidestream

diversion channels, similar to the MWRDGC's Cal-Sag waterway SEPA

stations. SEPA stations require access to a significant stretch of land parallel

and adjacent to the waterway.

Figure 4.6 is a schematic of a three-step weir aeration station.

SCREW PUMP FROM WATERWAY

DISCHARGE

TO WATERWAY

Figure 4.6 – Schematic of 3-Step Weir Supplemental Aeration System

4-14

FINAL 01/12/07

Cascades.

Cascades are defined as structures which cause water to rapidly

flow down step inclines in a violent manner without intermittent free-falls

followed by pooling.

Three-step cascades are located on two dams in the Fox River in

Northeastern Illinois. The dam aeration coefficient for these two dams,

determined from extensive field measurements, are 0.65 and 0.72. These

values are only a fraction of the range of values (2.4-4.1) recorded for the 3-

step SEPA facilities on the Cal-Sag Channel.

III.

Mechanical Surface Aerators.

Historically, mechanical aerators have been

classified relative to the axis of rotation, i.e., either horizontal or vertical. These

classifications are further subdivided into surface and submerged types.

Modern innovations, however, have produced hybrid systems that differ from

these simple forms. Virtually all mechanical aerators are designed to mix,

aerate, and facilitate the movement of water, and are quite adaptable for use in

supplementing stream DO. Typically mechanical aerators have an oxygen

transfer rate of 2.0 to 4.0 lbs 02/HP-hr.

Critics of mechanical surface aerators say they provide more mixing than

aeration and that in deep water minimal turnover of the deeper water is achieved.

Moreover, they are vulnerable to damage during high wind, cold weather, high

stream flows and from floating trash. Also, their aeration efficiency can be

reduced when eddy currents and wind move the downstream aerated water

slightly upstream.

Basic surface mechanical aerators have been in use for over 60 years. The

MWRDGC's instream aeration studies conducted during warm weather

conditions above the Lockport dam during 1926 and 1963 used a Yeoman's

Brothers Company HiCoWave Aerator. In the U.S., the earliest installation of

surface mechanical aerators as instream aerators was on the Great Miami River

in Ohio. Full scale instream aeration studies were conducted during 1965 on the

Upper Passaic River and during the late 1960's on the Delaware tidal basing.

Figure 4.7 shows a schematic of a mechanical surface aerator.

IV.

Compressed Air U-Tube Bubble Contactor.

A U-Tube aeration system is a gas

transfer process. The "U-Tube" designation is derived from the vertically-

oriented, geometric configuration of the water flow into which air or oxygen is

injected.

A deep shaft or hole is bored near the water body and is divided by either a flat

baffle or a concentric tubular baffle. The shaft and baffle are extended a few feet

above the surface of the water body. The baffle ends a few feet above the

bottom of the shaft. Aerated or oxygenated water is forced down one side of the

flat baffle or inside the tubular one.

The downward water velocity is designed to exceed the buoyant velocity of the

air or oxygen bubbles that are released into the water column. Consequently,

the bubbles are transferred downward and around the end of the baffle at the

bottom, thus, the name U-Tube. This process temporarily pressurizes the

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MOTOR

WATER GUIDE PANEL

WATER INLET PIPE ?

FINAL 01/12/07

bubbles via the large increase in hydrostatic head with the U-Tube. This

increases the saturation concentration which, in turn, increases the DO deficit

thereby creating a greater driving force for the adsorption of oxygen into the

water column. At sea level, a 34-foot head of water creates approximately two

atmospheres of pressure inside a gas bubble (one due to the air pressure and

one due to the water pressure).

Figure 4.8 shows a schematic of a flat-baffled U-Tube being fed low-pressure

compressed air.

Typically, U-tubes can produce OTE's as high as 90 percent.

Figure 4.7 – Mechanical Surface Aerator

LOW PRESSURE AIR\

Figure 4.8 — Schematic

of Compressed Air U-Tube Contactor

FINAL 01/12/07

Vaporized High Purity Oxygen

(HPO). The use of pure oxygen injection into a

water body in lieu of atmospheric oxygen has been heavily promoted for over 35

years. Most installations used "trucked-in" liquid oxygen stored in pressurized

cylinders. However, a few installations have been designed to generate pure

oxygen on site.

Most applications are for deep water bodies such as lakes, reservoirs, and deep

running rivers such as those found below high head hydropower dams. Some

success has been achieved by creating artificially deep injection points by

injecting the pure oxygen into excavated deep vertical shafts. The basic units

inclusive in all designs are a liquid oxygen storage tank, an air-to-air vaporizer, a

pressure control system, a bank-side contactor for open water applications, or a

side-stream contactor for injection back into the waterway.

The OTEs of HPO systems are highly variable but can be as high as 90 percent.

Pressurized Water Injection With Diffusers.

This system mixes

oxygen and water in a pressurized contactor tank. A stream of water is

pumped from the water body for use in the contactor. The oxygenated

water is then returned to the water body where it is distributed. Several

proprietary systems are available, of which the Speece Cone system

marketed by ECO2

is typical.

A conical contactor can be used to mix pressurized water with atomized

pure oxygen. These units are typically found in deep lakes, estuaries,

and sidestreams on large rivers below hydropower dams. Figure 4.9

shows a schematic of a conical pressurized water HPO contactor. This

super oxygenation technology reportedly can produce supersaturated DO

concentrations from 50 to 100 mg/L in water when mixed with pure

oxygen in the gas-water cone contactor.

CONE DIFFUSER

OXYGEN TANK

WATERWAY OR FORCE MAIN

FINAL 01/12/07

OXYGEN VAPORIZER

Figure 4.9 — Schematic of Pressurized HPO Contactor

FINAL 01/12/07

U-Tube Bubble Contactor.

The concept of a U-Tube bubble contactor was

previously discussed. While these installations can operate using either

compressed air or pure oxygen, many are designed to use pure oxygen "trucked"

to the site.

Successful U-Tube oxygenators have been established on *deep rivers like the

35-foot deep reach of the Tombigbee River in Alabama. A 175-foot deep bore

hole was needed. It produces a 50 mg/I DO concentration at the injection point.

The relatively deep river prevented an immediate loss of oxygen to the

atmosphere. However, shallow streams and rivers may not be capable of

absorbing the oxygen before it comes into contact with air and becomes lost as a

gas into the atmosphere.

Mobile (Barge-Mounted) Dispersion.

During the early 1970s researchers

at Rutgers University conducted experiments oxygenating the Passaic River

estuary with pure oxygen. The oxygen tank and diffusers were mounted on a

barge that would transverse the low-DO water in the estuary and disperse the

oxygen via the diffusers which were submerged along side the barge.

In 2004, the Liverpool England Harbor authorities deployed a mobile oxygenation

barge specifically designed and constructed to treat the harbor for low DO

problems (Figure 4.10). A fine bubble diffuser distributes the super oxygenated

water at depths from 3 to 25 feet. This system can achieve OTEs as high as

90%.

Figure 4.10– Barge Mounted HPO Diffuser System

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FINAL 01/12/07

VI.?

Screw Pump Aeration. The screw pumps for the existing SEPA stations exhibit

significant aeration capabilities. The Oxygen Transfer Rate (OTR) of screw

pumps is expressed as pounds of oxygen transferred to the liquid per unit

horsepower-hour of the drive motor. The average OTR for Stations 3, 4, and 5

screw pumps were found by the MWRDGC to be 0.91, 0.97 and 0.91 lbs

02/hp/hr,respectively.

Conceivably, a side stream aeration station could be

specifically designed using only screw pumps for providing aeration.

EVALUATION

Advantages and Disadvantages of Technologies

In order to simplify the discussions of the advantages and disadvantages of the long

listed alternatives, these technologies will be grouped into the following categories:

Air Diffusion Systems

Head Loss Structures

Mechanical Aerators

U-Tube Aerators

High Purity Oxygen Systems

Screw Pumps

Below is a discussion of the advantages and disadvantages of these six categories.

Air Diffuser Systems

The use of compressed air diffusion systems is a proven method for supplemental

aeration of waterways. Although there have been operational issues associated with the

Devon and Webster in-stream aeration stations, these compressed air diffusion systems

have been in operation for over 25 years and are a fairly reliable method for providing

aeration of the NBCR.

Jet aerators have not been applied to waterway aeration but this method of air diffusion

has been proven to be reliable and effective in wastewater treatment aeration tanks. Jet

aerators offer the advantage of good mixing and the elimination of dead zones. Jet

aerators are much less likely to clog compared to fine bubble diffusers.

Table 4.1 contains a summary of the advantages and disadvantages of air diffusion

systems.

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FINAL 01/12/07

TABLE 4.1

AIR DIFFUSION SYSTEMS – ADVANTAGES

DISADVANTAGES

Advantages

Disadvantages

Proven and well known

Diffuser area will tend to collect waterway

debris

No significant waterway traffic obstruction

Blowers and pumps are simple to operate

With appropriate design, can meet variable

oxygen demands

Requires significant shore area for blowers

or pumps

Widely available from many manufacturers

May not be applicable to areas where

periodic dredging is required.

performance specification

Jet aerator may aid mixing and eliminate

dead zones

Little operating experience for jet aerators

for supplemental aeration

Head Loss Structures

Head loss structures offer a simple way of adding oxygen to waterways. The existing

SEPA stations are an example of head loss structures which have been in operation for

many years providing a reliable method of waterway aeration.

The MWRDGC SEPA stations do have operational issues. These include aquatic weed

growth and excessive sediment deposits in the. pools. Since these structures need to be

placed on-shore to prevent waterway traffic obstruction, the shore space required is

quite high especially compared to compressed air diffusion systems.

Table 4.2 contains a summary of the advantages and disadvantages of head loss

structures.

TABLE 4.2

HEAD LOSS STRUCTURES – ADVANTAGES

DISADVANTAGES

Advantages

Disadvantages

Except for pumping to side stream sites,

no mechanical or electrical equipment is

operated or maintained.

Pumping to a side stream site is required

to avoid waterway traffic obstruction

aesthetically pleasing

Side stream sites can only treat a fraction

of the total stream flow

sharp-crested weirs have been developed

deposits require periodic maintenance of

side stream pool

Low lift screw pumps provide beneficial

additional aeration

FINAL 01/12/07

Mechanical Surface Aerators

Mechanical surface aerators have been successfully used to provide supplemental

aeration to waterways. These units are simple and rugged with low maintenance

requirements.

However, they have high power demand compared to compressed air diffusion systems,

which explains why mechanical aeration systems used in wastewater treatment have

been replaced by compressed air fine bubble aeration systems. Also, the units are not

attractive and they cause nuisance noise.

Table 4.3 contains a summary of advantages and disadvantages of mechanical surface

aerators.

TABLE 4.3

MECHANICAL SURFACE AERATORS – ADVANTAGES

DISADVANTAGES

Advantages

Disadvantages

Simple to operate

Presents waterway traffic obstruction;

this can be mitigated

Rugged systems with low maintenance

Are not aesthetically pleasing

Vulnerable to damage from high wind, cold

weather and high stream flows

performance specification

High power demand

U-Tube Aerators

U-Tubes have a high oxygen transfer efficiency and can provide a wide range of

aeration quantities. But they have high capital costs and access for maintenance is

difficult.

Table 4.4 summarizes the advantages and disadvantages of U-Tube aeration systems.

TABLE 4.4

COMPRESSED AIR U-TUBE CONTACTORS –ADVANTAGES & DISADVANTAGES

Advantages

Disadvantages

High oxygen transfer efficiency

Access for maintenance is difficult since

the tubes are usually placed underground

High Purity Oxygen Systems

The use of high purity oxygen (HPO) in conjunction with various diffusion systems has

been highly promoted over the past 30 years, and its application has increased

significantly over the last decade. The fact that dissolved oxygen concentrations in

water can be significantly increased under pressurized conditions is not disputable,

however, what is questionable is how much of this supersaturated gas remains in

solution and remains usable upon exposure to normal atmospheric pressure. The HPO

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FINAL 01/12/07

supplemental aeration systems, historically, have been applied only to deep bodies of

water such as reservoirs and deep rivers such as those which commonly prevail below

high-head power dams and flood control structures. Release to water depths of 60 feet

or more, with little turnover or mixing, provides the time for the DO to disperse and mix

before reaching the surface of a water body. Shallow rivers and streams may not

provide the detention time needed for the dispersion of the DO in the water body before

being lost to the atmosphere upon exposure at the water surface. Efficient dispersion of

supersaturated water in a low D.O. stream is dependent upon the design of the diffuser

system which delivers the supersaturated water stream.

Table 4.5 contains a summary of the advantages and disadvantages of High Purity

Oxygen systems.

TABLE 4.5

HIGH PURITY OXYGEN – ADVANTAGES & DISADVANTAGES

Advantages

Disadvantages

Excellent oxygen transfer efficiency

Dependent on future price for pure oxygen

Small on-shore space requirements

Increased truck traffic

Small space required for trucked in-

Can be operated to meet varying oxygen

On-site storage of a potentially hazardous

demands

material

Complicated operation and maintenance

May not be efficient for shallow waterways

Screw Pumps

As stated previously, screw pumps have OTR's of about 0.9 lbs 0

2/hp/hr. This is a rather

low OTR compared to fine bubble systems with OTR of 1.97 – 3.2 lbs 02/hp/hr

("Wastewater Treatment Plants, Planning Design and Operation" by S. Quasim) or even

mechanical surface aeration with OTE's of 1.0 to 2.0 lbs 0

2/hp/hr.

Thus, screw pumps by

themselves are low efficiency aerators and their use would not be justified unless they

would be useful for operation in conjunction with other aeration devices. For example,

screw pumps are used in conjunction with free fall weirs at the MWRDGC SEPA

stations.

Therefore, screw pumps were eliminated as a long list supplemental aeration

technology. However, they will be carried forward as a low IA pumping method for head

loss structures.

Scoring of Qualitative Economic and Non-economic Criteria Matrix

The final long list of possible supplemental aeration technologies is as follows:

IA Fine Bubble Porous Ceramic Diffusers

IB Membrane Diffusers

IC Jet Aerators

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FINAL 01/12/07

I IA Free-Fall Step Weirs with Screw Pumps

I IB Cascades with Screw Pumps

III Mechanical Surface Aerators

IV. Compressed Air U-Tubes

VA Pressurized Oxygen Contactor

VB.U-Tube Oxygen Contractor

VC Barge Mounted Diffusers

These long list alternatives were evaluated using the following criteria and weighting

factors. These criteria and weighting factors were a consensus decision between CTE

and MWRDGC and can be found in Technical Memorandum-3 (TM-3).

Impacts Upon Neighbors

Expandability

Total

100

Each alternative was scored for each of the above criteria according to the following

Each alternative was then evaluated relative to the weighting factor for each criteria. For

each criteria, the score for each alternative is multiplied by the criteria's weight to arrive

at a total score for that criteria. For example, if an alternative receives a score of 3 for a

criteria with a weight of 10, the total score for that criteria is 3x10 = 30.

In other technical memorandums, only whole numbers were given as scores for

alternatives. However, CTE technical

experts found that it was necessary to give

fractional scores to some alternatives. This was due to the relatively small differences

between some of the supplemental aeration technologies.

Table 4.6 contains the scoring for each alternative for the evaluation matrix. Below is an

explanation of the scoring shown in Table 4.6.

Life Cycle Costs

Life cycle costs were based upon the general knowledge of the costs associated with the

systems and not based upon a specific cost estimate.

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FINAL 01/12/07

High purity oxygen systems are mechanically complex and the cost to purchase or

generate (on-site) the oxygen is high. Therefore all HPO systems were given a score of

1.0.

Mechanical surface aerators are high users of electrical power compared to other

aeration systems. Given the rising cost of electricity, this technology was given a score

of 1.0.

Cascades are poor aerators requiring high capital costs for a large pump station and a

large cascade. This technology was given a score of 1.0..

Free fall step weirs with screw pumps (SEPA concept) have better oxygen transfer

efficiency than cascades but require substantial land area and large structures and

pump stations. This was given a score of 1.5.

Jet aerators normally require a large blower station compared to fine bubble ceramic

diffusers since they have a lower oxygen transfer efficiency. Jet aerators also require a

substantial pump station. This technology

was

given a score of 2.0.

Membrane and ceramic diffusers have a high oxygen transfer efficiency and thus require

a relatively small blower station and do not require a pump station. However, membrane

facilities have a higher capital cost than ceramic diffusers. Thus, membrane diffusers

were given score of 2.0 and ceramic diffusers were given a score of 2.5.

Compressed Air U-Tubes have an excellent oxygen transfer efficiency and due to the

high dissolved oxygen achieved, require a small pump station. This technology was

given a score of 2.5.

FINAL 01/12/07

TABLE 4.6

EVALUATION MATRIX

Alternative

Life Cycle

Cost

Maintainability

Operability

Reliability

Energy

Efficiency

Impacts on

Neighbors

Expandability

Total Score

125

12.5

252.5

100

12.5

207.5

100

22.5

7.5

215

II. Head Loss Structures

12.5

7.5

210

12.5

7.5

150

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FINAL 01/12/07

TABLE 4.6 -EVALUATION MATRIX

III. Mechanical Surface Aerators

III.

165

IV. Compressed Air U-Tube Contactors

125

12.5

22.5

12.5

245.0

V. High Purity Oxygen

12.5

130

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FINAL 01/12/07

Maintainability

HPO systems were given the lowest scores (1.0 to 1.5) because of their mechanical

complexity. Barge mounted HPO diffusion was given the lowest score (1.0) of the HPO

alternatives because of the need to also maintain the barge transportation system.

Fine bubble ceramic diffusers are a proven technology but based upon the MWRDGC

experience at the Devon and Webster stations for supplemental aeration, this

technology was given a score of 2.0.

Membrane diffusers should have similar maintenance issues as fine bubble diffusers

and were given a score of 2.0.

Mechanical aerators are simple to maintain but maintenance in a waterway will be

difficult and these devices were given a score of 2.0.

Although compressed air U-Tube facilities are relatively small due to a high oxygen

transfer efficiency, pumps and blowers must be maintained and this technology was

given a score of 2.0.

Although the existing SEPA stations have had maintenance issues, maintenance has

not been excessive and a score of

2.5

was assigned to this technology.

Lastly, jet aerators were given a score of 2.5 since there are no diffusers to replace or

maintain.

Operability

HPO systems are complex to operate and were given the lowest scores. Barge

mounted diffusion requires significant navigation skills and was given a score of 1.0 and

the other two HPO systems were given a score of 1.5.

Mechanical aeration systems can only be turned off or on as needed to meet DO

conditions. As such, they present operational challenges and were given a score of 2.0.

Membrane diffusers were given a score of 2.5 because of their short operating history

and no known use for waterway aeration.

Fine bubble ceramic diffusers, jet aerators, free fall weirs, U-tubes and cascades were

all given a score of 3.0. These devices are relatively simple to operate and offer the

operator significant control.

Reliability

Cascades and membrane diffusers were given the lowest score of 1.0. Cascades are

poor aerators and their ability to reliably produce the desired waterway DO level is

questionable. There is no known use of membranes for waterway aeration, thus

reliability for this application is unknown.

HPO systems can be reliably operated to meet a variety of waterway DO levels, thus

these systems were given a score of 2.0.

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FINAL 01/12/07

Fine bubble ceramic diffuser systems have proven reliability for wastewater applications

but the MWRDGC experience at the Devon and Webster aeration stations indicates that

a score of 2.0 should be applied to this technology.

Step weirs have been used by the MWRDGC to reliably provide supplemental aeration

of waterways and were given a score of 3.0.

U-tubes and jet aeration do not have a significant operating history for supplemental

aeration and were given a score of 1.5.

Energy Efficiency

Mechanical aerators, cascades and the three HPO options were all given a score of 1.0.

Mechanical aerators have a very high energy demand to transfer oxygen. Cascades

produce poor aeration in relation to the pumping energy required. The HPO systems

utilize high head pumping and significant energy is required to generate the HPO

whether it is purchased or produced on-site.

Jet aerators have high energy demands for pumping and blowers and were given a

score of 1.5.

Compressed air U-Tubes, and fine bubble ceramic and membrane diffusers require

relatively low electrical energy and were given a score of 2.5.

Free fall step weirs using screw pumps are relatively energy intensive since screw

pumps are not energy efficient. Thus this technology was given a score of 2.0.

Impacts on Neighbors

Mechanical aerators and barge mounted HPO diffusers were given the lowest score of

1.0. Mechanical aerators are noisy, produce a visible water spray, and represent a

hindrance to boat traffic. A barge mounted aerator can hinder boat traffic, is highly visible

and will not be aesthetically pleasing.

A HPO contactor will require the use of HPO which would be generated on-site or

transported to the site. The operation of a HPO generation plant or transportation of

HPO to the site would be objectionable to nearby residences. These systems were

given a score of 2.0.

All other aeration systems were given a score 3.0 due to their minimal impacts on

neighbors.

Expandability

Free fall step weir facilities and cascades require considerable land space and

significant site preparation. Thus these facilities were given a score of 1.5.

Compressed air U-Tubes and HPO U-Tubes were given a score of 2.5 because of the

deep excavation required for this technology. All other technologies were given a score

of 3.0 because of ease of expansion.

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FINAL 01/12/07

Short List of Technologies

Based upon the evaluation matrix discussed previously, the following four technologies

received the highest total scores:

Technology

Total Score

Ceramic Fine Bubble Diffusers

252.5

Compressed Air U-Tube

Thus these four technologies constitute the short list of supplemental aeration

technologies.

It should be noted that this short list includes two supplemental aeration technologies

which have a relatively long operating experience for the MWRDGC (namely Ceramic

Fine Bubble Diffusers and SEPA Stations) and two technologies which have relatively

little past operating experience for use in supplemental aeration (U tubesand Jet

Aerators). Since the main objective of this study was to determine the relative costs for

supplemental aeration and not to select a single technology for possible implementation,

no attempt will be made to recommend one of these technologies. Instead, a detailed

cost estimate for each of the four technologies will be conducted. Selection of a

technology for possible application to the SBCR and NBCR should be done after an

extensive review of the operating history of units currently being used for supplemental

aeration elsewhere. In addition, it would be worthwhile based upon the expenditures for

supplemental aeration to conduct pilot or lab studies of some or all of the short listed

technologies before making a final selection and beginning final design.

Since the passage of boat traffic is an important aspect of any supplemental aeration

system, this issue should be carefully considered as part of the recommended pilot or

lab studies. Also, boat traffic passage should be carefully considered when reviewing

the operating history of a supplemental aeration technology.

Land Availability for Supplemental Aeration

Figures 4.11 through 4.14 contain conceptual layouts for the 80 g/s (oxygen)

(15,200/lbs/day of oxygen) aeration stations for all four short-listed technologies. This

layout for the largest station was prepared so that the maximum space requirements for

the four technologies could be determined. The SEPA technology requires the most

area with a space requirement of about 1 acre for the 80 g/s (15,200 lbs/day) station. A

30 g/s SEPA station would require about 1/2 acre.

Using the space requirements for the SEPA station as the maximum space requirement,

aerial photographs were examined to determine if sufficient vacant land was available at

each of the four supplemental aeration sites. Appendix D contains four figures which

show each of the four aeration station locations with an overlay showing the land

requirements for the SEPA technology. The Diversey site was not large enough for a 1

acre footprint. However, it is large enough for a 1/2 acre footprint, which is the size

required at this location. The overlay on the Diversey figure in Appendix D shows a 1/2

acre overlay. Each site has the available vacant land space available for the SEPA

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FINAL 01/12/07

technology. Thus, any of the sites could be used for any of the four short-listed

technologies without the need for building demolition.

The cost estimates assume that the land needed for the supplemental aeration stations

would have to be purchased at a cost of $1.2 million per acre. This land cost is probably

conservative since the MWRDGC Engineering Department estimated the highest land

cost for property along the NBCR and SBCR to be $675,000 per acre. For simplicity,

the SEPA station land requirements were used to obtain land costs for each of the four

technologies. That is, one acre was assumed to be needed for a 80 g/s (oxygen) station

and 1/2 acre was needed for 30 g/s (oxygen) station.

Figure 4.11 — 80 g/s (Oxygen) SEPA Station Conceptual Layout

FINAL 01/12/07

The jet aeration system requires a building which would contain 19 pumps and 15

blowers. This arrangement is typically used for the KLA Systems Inc. (Assonet, MA).jet

aeration process used for cost estimation purposes for this report. This process uses

individual manifolds each with 32 jets. For the 80 g/s of oxygen aeration station, a total

of 19 manifolds are required. In the typical KLA system design, each manifold uses a

single pump and thus 19 separate pumps are required. To supply air to the 19

manifolds, the KLA system design includes 15 blowers (2 standby). The use of this

large number of blowers allows flexibility in supply and controlling air to the jet aeration

manifolds. If a design of a jet aeration system is contemplated in the future, in all

probability a smaller number of pumps and blowers would be selected. However for

conceptual cost estimation purposes, this initial design of the jet aeration system is

sufficient.

150'

FENCE

PUMP AND BLOWER BUILDING

FINAL 01/12/07

Figure 4.12 - 80 g/s (Oxygen) Jet Aeration Station Conceptual Layout

FINAL 01/12/07

.....

Figure 4.13 — 80 g/s (Oxygen) Ceramic Fine Bubble Diffuser Station Conceptual Layout

Figure 4.14 – 80 g/s (Oxygen) Compressed Air U-Tube Station Conceptual Layout

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FINAL 01/12/07

Cost of Supplemental Aeration Stations

Appendix A contains the various unit costs utilized to determine the Capital and

Operating costs for the four supplemental aeration stations. The unit costs were derived

either from TM-3 and/or TM-1WQ.

Appendix B contains the detailed spreadsheets that were used to estimate the capital

costs for the 30 g/s (oxygen) supplemental aeration stations. Appendix C contains the

detailed spreadsheets that were used to estimate the operating and maintenance costs

for the 30 g/s supplemental aeration stations. Cost estimates for the 80 g/s aeration

stations were extrapolated based upon the costs for the 30 g/s (oxygen) stations.

Capital and operating costs were estimated for each of the short-listed supplemental

aeration technologies which were:

The scope of this conceptual level study precluded an analysis of the application of the

four short listed technologies to the various supplemental aeration sites. It may well be

that site conditions will dictate the choice of a supplemental aeration technology. Also it

may be necessary to conduct full-scale and/or pilot plant studies to determine the design

criteria for supplemental aeration stations. For example, the MWRDGC conducted pilot-

plant tests of the SEPA concept and the information from these tests were used to

design the existing five SEPA stations on the Cal-Sag Channel.

Table 4.7 contains a summary of the capital and annual maintenance and operation

costs for the four short-listed technologies. These are the total costs for implementing

these technologies at the four locations and aeration capacities determined by the

Marquette Modeling runs.

U-tubes and ceramic diffusers represent the lowest present worth. However, these cost

estimates are planning level and are based upon general design factors which may not

be applicable to the site-specific conditions on the SBCR and NBCR. As stated

previously, it would be prudent to select a supplemental aeration technology based upon

a review of the operating history of the existing MWRDGC supplemental aeration

facilities and other similar facilities elsewhere. Also the design criteria for the

supplemental aeration stations should be verified by pilot and/or laboratory studies.

Lastly, a rigorous use of the Marquette Model should be undertaken complete with a

sensitivity analysis to determine the final sizing and locations of the supplemental

aeration stations. If necessary the model may be refined to ensure that this sizing and

location represents the best simulation for the NBCR and SBCR.

FINAL 01/12/07

TABLE 4.7

SUMMARY'OF CAPITAL AND ANNUAL COSTS

Cost of Four Supplemental Aeration Stations on NBCR and SBCR

Total Capital

Annual O&M

Total Present

Worth

As can be seen in Table 4.7, the range of costs for supplemental aeration for the NBCR

and SBCR are as follows:

Capital Costs

$35.5 Million – $89.9 Million

Annual Operation and Maintenance Costs

$554,000 – $2.6 Million

Total Present Worth

$47.4 Million – $132.6 Million

SUMMARY AND CONCLUSIONS

A planning level study was conducted to determine the potential technologies and costs

for adding supplemental aeration to the NBCR and SBCR. The supplemental aeration

provided would be in addition to the aeration provided currently at the Devon and

Webster Avenue diffused aeration stations. To determine the size and location of the

additional aeration stations, a water quality simulation model developed by Marquette

University for the MWRDGC was used. Since the IEPA has not reached a decision on

the DO target levels for the NBCR and SBCR, a target DO of a minimum of 5 mg/I to be

achieved 90% of time was selected.

After a review of a long list of technologies using an evaluation matrix which included

both non-economic and economic factors from four technologies were selected for a

detailed opinion of probable cost estimate.

The opinion of probable cost estimate was based upon constructing a total of 4

additional stations on the SBCR and NBCR. These 4 stations were found to be

necessary by Marquette Model runs to achieve the DO target levels 90% of the time for

the data base simulated in the Marquette Model (2001 and 2020). The total capital cost

ranged from $35.5MM to $89.9MM. The total annual operation and maintenance cost

ranged from $554K to $2.6 MM.

It should be noted that the main purpose of the study was to determine the magnitude of

the costs associated with supplemental aeration of the NBCR and SBCR and not to

select a technology for possible application. Thus, it would be necessary to conduct an

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FINAL 01/12/07

in depth study of the operating experience of the four technologies for supplemental

aeration. This is especially true for jet aerators and U-tubes where there is little

operating experience. Also pilot and full-scale studies of some or all of the technologies

should be initiated to refine the cost estimates, help to select a technology for possible

implementation, and develop design criteria.

It should also be emphasized that a decision to implement supplemental aeration of the

NBCR and SBCR should only be reached after an integrated study of all IEPA requested

water quality management options has been undertaken. This study would determine

the relative costs and benefits of these options and then determine their priority for

potential implementation. Such an integrated study is beyond the scope of this

Technical Memorandum.

FINAL 01/12/07

APPENDIX A

Unit Costs Used in Cost Estimates

FINAL 01/12/07

UNIT COSTS USED IN COST ESTIMATES

Life cycle cost (LCC) analysis requires the development of certain constants that will be

used throughout the evaluation of alternatives. Values used for constants are presented

below. These values have been developed in consultation with MWRDGC staff and

represent actual values or agreed upon assumptions.

1.?

Present Worth Factors for Life-Cycle Costs

Annual inflation rate

• Annuity Present Worth Factor (with inflation)

Structural Facilities

• Mechanical Facilities?

Electrical Cost

$0.075/kW-hr

Labor Rates Per Hour Including Benefits (11

5. Parts and Supplies?

5 percent

6. Contractor Overhead and Profit (2)?

15%

7. Planning Level Contingency (3)?

30%

Engineering Fees including Construction Management

(4)?

20%

(1) A multiplier of 2.9 was used to reflect benefits as provided by the

MWRDGC.

(2)

Percent of Total Construction Cost

(3) Percent of Total Construction Cost plus Contractor Overhead and

Profit

(4)

Percent of Total Construction Cost, Contractor Overhead and Profit

plus Contingency

FINAL 01/12/07

APPENDIX B

Detailed Capital Cost Estimates for Four Short-Listed Supplemental Aeration

Technologies

FINAL 01/12/07

APPENDIX C

Detailed Annual Cost Estimates for Four Short-Listed Supplemental Aeration

Technologies

FINAL 01/12/07

APPENDIX D

Figures Showing Land Availability for Four Supplemental Aeration Stations

FINAL 01/12/07

Figure D-1 – Land Availability for 30 g/s SEPA station at Diversey Avenue and the

North Branch Chicago River

Proposed

Aeration

Station Site

FINAL 01/12/07

Figure D-2 — Land Availability for 30 g/s SEPA station at Chicago Avenue and the

North Branch Chicago River

FINAL 01/12/07

Figure D-3 – Land Availability for 30 g/s SEPA Station at 18

th Street and the South

Figure D-4 —Land Availability for 80 g/s SEPA station at Halsted Street and the

South Branch Chicago River

FINAL 01/12/07

APPENDIX B

Detailed Capital Cost Estimates for Four Short-Listed Supplemental Aeration

Technologies

TABLE BA

CAPITAL COST ESTIMATION FOR U-TUBE SUPPLEMENTAL AERATION (30 g/s)

MIscellaneOus Sltework

100

$36.00

$3,600

Miscellaneous Sitewotir

Split Block Masonry Building

Vertical turbine Pumps and Appurtenances

Drill & Prep 12' die U-Tube Shaft

115

$1,742.00

$200,330

Casing Material (Welded Steel, 1')

87300

$2.00

5174,600

Install U-Tube Casing

Install Bottom Plug (Concrete and Mortar)

$760.03

$18,750

$18,760

Pump Water from Shaft and Prepare Casing

$52,500.00

$52,500

Bubble Collector and Appurtenances

Pressure Gages/Transmitters

Alr

Supply Piping and Appurtenances

20' Pump control Valve

Pressure Regulating Station

Lateral Installation (Within Water Column)

4,000

$94.00

$376,000

ELECTRICAL AND INSTRUMENTATION

Control systems and Instrumentation

Contractor OH&P 0 15%

$436,514

Subtotal

93,346,610

Planning Level Contingency 0 30%

Legal and Fiscal Fees 0 15%

$652,689

Engineering Fees Including CM 0 20%

Suppl. Aeration COST9.x1sU-TUBE 30 gms per

see •

CAPITAL

TABLE B.2

CAPITAL COST ESTIMATION FOR JET AERATION (30 g/s)

Mobilization for dredging

8333

Blower & Pump Bidg. Excavation

Pump and Blower Building

Pumps, Blowers, Manifolds

Pressure Gages/Transmltters

Air Supply Piping and Appurtenances

20' Pump control Valve

ELECTRICAL AND INSTRUMENTATION

Control systems and Instrumentation

Planning Level Contingency 0 30%

Legal and Fiscal Fees @ 15%

Engineering Fees including CM ®20%

Suppl. Aeration COST9.xlsJet Mr 30 gms per sec-CAPITAL

TABLE B.3

CAPITAL COST ESTIMATION FOR SEPA 30 g/s STATION

OH&P

Planning Level Contingency 0 30%

Costs

and

Fees

sts were obtained from existing SEPA station construction costs, updated to 2006 rates using ENR Index of 7660.

B-4

Suppi. Aeration COST9.xIsSEPA 30 gms per sec CAPITAL

TABLE B.4

CAPITAL COST ESTIMATION FOR CERAMIC DIFFUSER SYSTEM

(30 g/s)

DIVISION IITEM DESCRIPTION

CONCRETEBackfillBlower

River DredgingPilingDemBldg.

Pumpingfor

Excavationdredging

DAYCYCYCYSFLSSF

20000150008333481667201

$56,500.00'

$3,600.00S52$0$30.00$20.00$8.00$7.00

$1,050,000$450,000$166,667$72,000$58,500$3,852$4,667

$1,050,000$166,6675450,000$72,000$56,500$3,852$4,687

PumpCONSTRUCTIONActuatorFilter

EALSEA

LSLS

1111

510%000.00590,000.00525,000.00$15,000.00520,000.00$19,000.00

5100,000$19,000$75,000$90,000$15,000$20,000

40%40%

$30,000$38,000

$100,000$105,000$128,000$19,000$15,000$20,000

PipeINSTRUMENTATIONand

Appurtenances

EAEAEALFLF

1000100080

$5,000.00$3,00100$150.00$15.00

529.00

$15,000$12,000$29,000$5,000$9,000

40%40%40%40%40%

$11,600$2,000$4,800$3,60056,000

$21,000516,800$12,800$40,600$7,000

$40,000.00560,000.00$6,000.00

$60,000$40,000$8,000

40%40%

40%

$24,000$16,000$3,200

$11,200$56,000$84,000

Level Contingency 0 30%

&Usu.

Suppi Aeration COST9AlsOlfruser 30 gms per sec-CAPITAL

ffi

‹

EL.

233

g-.

?61

omL,.

o88

,T,

$3T2

CAPITAL COST ESTIMATION FOR JET AERATION (80

g/s)

UNIT COST

Malt/Alton for dredging

$3,800.00$52.50$30.00

$2,800,000$1,200,000$192,000

$1,200,000$2,800,000$192,000

BacictliBlower

& Pump Bldg. Excavation

Pump and Blower Bulking

Pumps, Blowers, Manifolds

Pressure Gages/Transmkters

Air Supply Piping and Appurtenances

20' Pump control Valve

ELECTRICAL AND INSTRUMENTATION

Control systems and Instrumentation

Contractor CHAP 0 15%

51,768,606

Subtotal

$13,714,183

Planning Level Contingency

Legal and Fiscal Fees 0 15%

$2,674,266

Engineering Fees Including CM 0 20%

TABLE B.7

CAPITAL COST ESTIMATION FOR SEPA 80 gfs STATION

PROJECT NO. 40779

Contractor OH&P @ 15%

Legal and Fiscal Fees @ 15%

Engineering Fees Including CM @ 20%

(1) Costs were obtained from existing SEPA station construction costs, updated to 2006 rates using ENR Index of 7660.

B-8

Suppl. Aeration COST9.xisSEPA 80 gps-CAPITAL

TABLE B.8

CAPITAL COST ESTIMATION FOR CERAMIC DIFFUSER SYSTEM (80 g/s)

MobilizationfordredgingDredgingPlling

CYSFLS

40000222221

$150,666.67$20.00$30.00

$1,200,000;$444,444]$160,6671

$1,200,000$444,444$150,667

BlowerRldg.Excavafanill

CYCY

1284177853

$3,600.00$8.00$7.00

$192,000;$10,272$12,444;

$192,000$10,272$12,444

Alr Supply Piping and Appurtenances

ELECTRICAL AND INSTRUMENTATION

Control systems and Instrumentation

Contractor OH&P @ 15%

$1,137,312

Subtotal

$8,719,390

Planning Level Contingency @ 30%

$2,615,817

Subtotal

Misc. Capital Costs

Legal and Fiscal Fees @ 15%

$1,700,281

Engineering Fees Including CM @ 20%

Suppl. Aeration COST9AsDiffuser 80 gps-CAPITAL

FINAL 01/12/07

APPENDIX C

Detailed Annual Cost Estimates for Four Short-Listed Supplemental Aeration

Technologies

TABLE 0.1

ANNUAL O&M COSTS FOR U-TUBE 30 gis AERATION SYSTEM

PRESENT WORTH FACTOR.

AND

AND

Suppl. Aeration COST9.r.IsU-Tube 30 gms per sec - O&M

ANNUAL

TABLE C.2

O&M COSTS FOR JET AERATION

TOTAL PRESENT WORTH 0 & M COST

$9,006,236

C-3

Suppl. Aeration COST9.xlsJet Aer 30 gms per sec-O&M

TABLE C.3

ANNUAL O&M COSTS FOR 30 g/s SEPA STATION

TABLE C.4

ANNUAL O&M COSTS FOR CERAMIC DIFFUSER SYSTEM

Average

TOTAL PRESENT WORTH 0 & M COST

$3,730,308

C-5

Suppl. Aeration COST9.AsDifluser 90 grass per sec OEM

ANNUAL

TABLE C.5

O&M COSTS FOR U-TUBE 80 g/s

TOTAL PRESENT WORTH 0 & M COST

$4,751,637

C-6

Supt. Aeration COST9idsSup. Aer. 80 gifts per sec•O&M

ANNUAL

TABLE C.6

O&M COSTS FOR JET AERATION

$40Nh

(5/hr)

(5)

TOTAL PRESENT WORTH 0 & M COST

$23,355,351

C-7

Suppi. Aeration COST9.xlsSup. Mr. 80 grns

per sec-O&M

TABLE 0.7

ANNUAL O&M COSTS FOR 80 g/s SEPA STATION

Stipp!. Aeration COST9.,dsSup. Aer. 80 grass per sec-O&M

TABLE C.8

ANNUAL O&M COSTS FOR CERAMIC DIFFUSER SYSTEM 80 g/s SYSTEM

TOTAL PRESENT WORTH 0 & M COST

$9,676,064

C-9

Suppl. Aeration COST9.xlsSup. Mr. 80 gms per sec-O&M