v;
United States
Environmental Protection
Agency
Region 5
230 South Dearborn Street
Chicago, Illinois 60604
May 1983
Water Division
&EPA TECHNICAL EVALUATION
Impact of Combined Sewer Overflow
Control Alternatives for the
Ecorse Creek Basin
Wayne County, Michigan
905R83111
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TECHNICAL EVALUATION
Impact of Combined Sewer Overflow
Control Alternatives for the
Ecorse Creek Basin
Wayne County, Michigan
Prepared By:
US EPA
230 S. Dearborn
Chicago, IL 60604
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CONTENTS
Page
' I. Introduction 1
II. Ecorse Creek 3
/"
III. Existing Situation 7
A. Existing System 7-
»
B. Approved Plan 9
IV. Alternatives 12
V. Analysis 15
/
A. Methodology 15
B. Costs 15
C. Benefits . 18
D. Other Issues 20
VI. Implementation Steps 23
VII. Conclusions 25
VIII, Recommendations 26
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I. Introduction
On February 15, 1983, the Honorable John Feikens, Chief United States
District Court Judge set a schedule of compliance for planning, engineer-
ing and funding of the approved Sewer Separation/Retention Basin project in
Allen Park, Michigan. The order specifies that notice to proceed with con-
struction shall be given on or before March 21, 1984.
The proposed project is part of an overall plan for Allen Park in which
combined sewers would be separated into a stormwater conveyance system and a
sanitary wastewater conveyance system. This is part of a basinwide plan of
stormwater management in which a number of communities in the North Branch
Ecorse Creek Basin have separated or are in the process of separating com-
bined sewer systems. The aims of this basinwide plan are to reduce pollution
in Ecorse Creek, and control flooding in the area which occurs during heavy
rainstorms. The basinwide plan is the result of numerous studies conducted
over the past decade. The remaining portion of the plan to be implemented is
the anea tributary to LeBlanc Drain, and specifically the system in Allen
Park which contributes combined sewage to LeBlanc Drain.
On March 18, 1983, in a hearing held before Judge Feikens, the United States
Environmental Protection Agency requested that the Court permit it to eval-
uate technical questions concerning the overall concept of and alternatives
to the sewer separation/retention basin project for the City of Allen Park.
As proposed, this evaluation would not cause a delay'from the Court's
schedule for implementation of pollution control in Allen Park. Judge
Feikens subsequently granted U.S. EPA's request but cautioned that any
alternative to the approved project would have to be accompanied by ample
justification to the Court that the alternative would: 1) provide equivalent
or superior pollution control (compared to the approved project), 2) be
significantly less costly, and 3) be capable of being implemented within the
time frame of the approved project.
The study carried out over the last several weeks has been focused upon
information and studies brought forth by Allen Park (through its engineer-
ing consultant, Willliams & Works), which contend that the objective of
pollution control is better served, and at significantly less cost, by
alternatives to the proposed sewer separation project. It must be empha-
sized that the issue of "better" alternatives at this time be viewed in an
historical context of scientific and engineering thought; and the political,
regulatory and economic climate of the mid-1970's. At the time the Sewer
Separation/Retention Basin project was formulated and approved, the 100 per
cent control of combined sewer overflow pollution throughout the nation was
believed to be a realistic and attainable goal from both a technological and
an economic standpoint. Several factors have since resulted in significant
modification of this goal.
1) The cost of controlling CSO pollution today far exceeds the esti-
mates made in the mid-70's.
2) The benefits of controlling CSO pollution in terms of enhanced water
quality and potential uses of the water resource are generally much
less than originally thought due to the intermittant nature of the
discharge, the dilution that occurs during storms, and the fact that
stormwater itself has a significant pollution impact.
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3) An economic downturn 1n the nation accompanied by Inflation and
higher taxes have sensitized the public to be more concerned about
costs and benefits of pollution control projects.
4) The funds appropriated by Congress for water pollution are much less
than required to achieve the objectives established in the Clean
Water Act.
5) It can now be demonstrated that funds expended on continuous flow
pollution control facilities (i.e. wastewater treatment plants and
components) rather than intermittent flow pollution control (i.e.
CSO control facilities) can deliver up to 10 times more pollutant
removals per unit of capital expenditure.
Finally, with respect to this project; it is quite probable that the sewer
separation actions taken by other communities in the basin contribute to the
viability of alternatives other than sewer separation for Allen Park* This
1s because the removal of sanitary flows from those communities' stormwater
systems has, in effect, minimized the impact of Allen Park's contribution
(through the overflow of combined sewage) to water quality problems in Ecorse
Creek. Alternatives proposing the separation of Taylor storm flows from
LeBlanc Drain together with the dilution of Allen Park sanitary flows by
footing drain water, infiltration and runoff and the treatment of substantial
quantities of stormwater by the Wyandotte Treatment Plant and District #5
facilities combine to result in less overall pollutant discharge to Ecorse
Creek.
In order to expeditiously conduct this study, the following items were
identified as being crucial to the investigation:
Clarification of technical assumptions and conclusions made by
Williams & Works, Inc.,
* Resolution of technical objections to those assumptions and con-
clusions raised by Wayne County Drain Commission (through its
engineering consultant, Wade, Trim, & Associates),
An independent analysis and validation of alternatives to sewer
separation,
* Evaluation of the impact that any alternative would have on the
overall goal of pollution abatement in the basin,
* An independent conclusion on the viability of alternatives to sewer
separation considering costs and implementation.
This report presents U.S. EPA's findings with respect to the issues and
objectives stated above and its conclusions and recommendations regarding
pollution control facilities for the City of Allen Park.
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II. Ecorse Creek
In 1969, the Michigan Department of Natural Resources (MDNR) conducted a
water quality study on the Ecorse Creek. It was found that the lower portion
of the creek was severely degraded as indicated by algae, growth deposits of
sludge on the creek bed, and other factors. The study identified the sludge
deposits as the principal source of BOO which caused low levels of dissolved
oxygen. The sludge depth reportedly ranged from 2 feet to 4.5 feet in the
main branch of the creek while depths up to 6 feet were the measured near the
LeBlanc Drain discharge. An analysis of the stream's aquatic life revealed
only pollution tolerant organisms were present. Combined sewer overflows
were identified as the major cause of this degradation.
In November of 1970, the State of Michigan cited the communities in the
Ecorse Creek basin for discharging untreated sewage into the waterway. They
were ordered to study the causes of the problem and derive solutions that
would halt the degradation of the creek.
The Wayne County Drain Improvement Board's study in 1971 cited LeBlanc Drain
as one of the most significant contributors of raw waste discharge. LeBlanc
Drain, during periods of storm activity, conveyed flows which exceeded the
River Drive Interceptor's capacity and discharged excess flows directly to
the Ecorse Creek.
Subsequent facilities planning was conducted but before regulatory approval
was made the U.S. EPA issued Program Guidance Memo No. 61 (PG-61) which
presented its policy on the use of construction grants funds for treatment
and control of combined sewer overflow and stormwater discharges. Since
PG-61 limited the grant eligibility of multiple purpose projects (i.e. pollu-
tion control/flood control), the eligibility of federal funding of facilities
recommended in the 1975 Ecorse Creek Facility Plan was substantially
reduced.
After a series of meetings between U.S. EPA, MDNR, and local officials, it
was decided in June, 1976 to segment the Ecorse Creek Facility Plan into 3
elements. Element 1, published in February, 1977, but not yet approved by
MDNR, contained an Infiltration/ Inflow Analysis (I/I) of the separated
sanitary sewers serving the northern portion of Allen Park which are tribu-
tary to the Detroit wastewater treatment plant. This report concluded tnat
I/I for this area was "non-excessive" and recommended construction of facili-
ties to adequately transport and treat all wastewater flow including I/I.
Element 2, published in February, 1977, recommended sewer separation within
the combined sewer districts of the Ecorse Creek basin to prevent the over-
flow of combined sewage. It did not, however, address the pollution of
Ecorse Creek caused by the discharge of stormwater from the basin after
separation. Element 2 was approved and the Cities of Taylor (upstream of
Allen Park) and Lincoln Park (downstream of Allen Park) subsequently sepa-
rated their remaining combined sewer systems.
Element 3 planning (not yet completed) includes evaluation of the remaining
sanitary sewer districts located in the western part of the Ecorse Creek
Basin (Volume 6-B), and evaluation of onsite wastewater treatment systems
(Volume 6-C). Volume 6-A of the Element 3 Facility Plan evaluates and
recommends solutions to water pollution problems resulting from stormwater
runoff, surface flooding, onsite wastewater systems, sanitary sewer systems,
and point sources of pollution.
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The Plan of Study Area Map shows the relationship of Taylor, Allen Park and
Lincoln Park to LeBlanc Drain, the North Branch Ecorse Creek and the Sexton-
Kilfoil Drain.
The State of Michigan has designated the use of Ecorse Creek as Recreational -
Partial body contact. According to Fred Cowles (MDNR), the numerical water
quality standards applicable to Ecorse Creek are:
Dissolved Oxygen - 5.0 mg/1 daily average
No value below 4.0 mg/1
Fecal Conform Bacteria - 1000 organisms/100 ml
pH - 6.5 to 8.8 ,
(Other narrative standards apply which are interpreted specific to a stream
In conjunction with an NPDES permit application.)
Recent visual inspection of Ecorse Creek along the South Branch (Sexton-Kil-
foil Drain), the lower portion of the North Branch and the Main Branch
revealed a stream whose lower reaches were long ago dedicated primarily to
urban and suburban drainage. The stream has been significantly altered from
Its natural state through widening, deepening, and the straightening of the
creek. The lower two miles have been channelized. All of this was designed
to permit greater flow capacity and enhanced drainage capabilities which were
required to protect the developing urban landscape. As a result, however,
flow velocity in the stream was substantially reduced while the loadings of
suspended solids, BOD, nutrients and other pollutants were Increasing due the
urban development of the basin. The stream's natural ability to cleanse it-
self of pollutants through flushing, wetlands filtration, and biological
activity were elminated or substantially reduced. These original modifica-
tions of Ecorse Creek to enhance urban drainage signaled the beginning of the
water quality degradation which is evident today.
Based on visual examination of characteristics such as turbidity, flow,
reaeration and flotables, the water quality in the South Branch in the
central and eastern parts of Taylor appear to be quite good. Land use in
this area is not intensely developed and in fact is rural except for the
strip development along the major roads.
As one moves downstream along the South Branch into the more intensely
developed urban areas of Allen Park, the water becomes much more turbid, the
channel appears to have been deepened, the banks are steep and are covered
with thick vegetation but flow was still apparent. Further downstream at
Toledo Road (Trenton Rd.) the channel has widened substantially and flow has
become hard to detect. The water at this point was very turbid, banks are
steep but not deeply cut and a substantial amount of trash such as shopping
carts, tires, and cable spools can be noted protruding from the water. These
kinds of conditions were observed further downstream in Lincoln Park to the
confluence with the North Branch. Parks and recreational areas along the
Stream in Lincoln Park are fenced to eliminate access to the water.
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In the lower reaches of the North Branch but upsteam of LeBlanc Drain (along
River Drive), water quality appeared severely degraded. Flow was difficult
to detect, the banks were steep and choked with vegetation. Where one could
get down to the water, sediments covered the bottom near the shore and
presumably across the stream bottom. Large floating pads of decaying algae
and other materials from upstream were observed as well as the accompanying
odor. Trash was also apparent in this area including tree stumps. These
degraded conditions were observed to extend downstream past the LeBlanc Drain
and the confluence of the North and South branches.
A final visual inspection was made at the railroad bridge downstream of the
steel mill on the Main Branch. At this point the bridge precludes any pass-
age of boats from the Detroit River, The flow is still difficult to observe
but water quality in terms of turbidity and flotables appears to be improved.
This improvement quite possibly is due in part to the "estuary" effect of the
Detroit River a short distance further downstream.
This visual inspection of Ecorse Creek leads to the conclusion that factors
related to the intense urban development upstream of LeBlanc Drain and the
modification of Ecorse Creek to enhance drainage substantially effects the
stream's existing water quality. It is believed that the stream may not meet
water quality standards far upstream of LeBlanc Drain. Furthermore, the low-
er portions of the creek and specifically the North and South Branches along
River Drive and the Main Branch of Ecorse Creek are not suitable or conducive
to any recreational use involving body contact of any kind. The 1000
organisms/100 ml fecal coliform bacteria standard is applicable specifically
to the partial body contact recreational use. Actual conditions, however,
both upstream and downstream of LeBlanc Drain preclude such uses. Therefore,
this fecal coliform standard does not appear to be appropriate particularly
during wet weather conditions.
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III. Existing Situation
A. Existing System
The Ecorse Creek Basin includes all or part of the following communities:
Allen Park, Lincoln Park, Taylor, Dearborn Heights and Ecorse. All commun-
ities in the basin have separated their combined sewers with the exception of
Allen Park. The separate storm runoff within the basin is conveyed to the
North Branch of Ecorse Creek or the Sexton-Kilfoil Drain (South Branch).
Separate sanitary sewage is delivered to the River Drive Interceptor (RDI)
and the Pennsylvania Interceptor and is conveyed to the Wyandotte Wastewater
Treatment Plant (WWWTP). Allen Park's combined sewage enters LeBlanc Drain
where it currently mixes with the stormwater from Taylor and Lincoln Park.
In order to understand the details of how this system functions, the'follow-
ing description starts at the upstream end of LeBlanc Drain in Taylor which
contains separated storm and sanitary sewers.
The Taylor storm flows are derived from the runoff of approximately 4,200
acres. This stormwater enters the LeBlanc Drain at a maximum rate of 100
cubic feet per second (cfs) through a system of gravity sewers and a regula-
tor device at the point of entry. Stormflows which exceed the 100 cfs regu-
lator or other constraints upstream in the system are stored in two retention
basins in Taylor. While originally the system was designed to pump all
stormwater to the Sexton-Kilfoil Drain from the south'retention basin, almost
all flows in the Taylor system are currently dewatered through the LeBlanc
Drain at up to 100 cfs. This is necessary because four combined sewers in
Allen Park are connected into the separated Taylor stormwater system. If the
system were to be placed in operation as designed, the dry weather sanitary
flows from these Allen Park combined sewers would flow to the retention basin
causing operational problems in that facility and would be pumped to
Sexton-Kilfoil Drain without treatment. To prevent this from
happening, the system continues to dewater through the LeBlanc Drain where
dry weather flows are discharged to the River Drive Interceptor (RDI) and
transported to the Wyandotte Wastewater Treatment Plant as shown in the
Existing System schematic.
Allen Park flows of combined sewage are derived from runoff from approximate-
ly 1900 acres of Allen Park, sanitary sewage from approximately 18,000
people, and flows from footing drains around houses which are connected to
the lateral sewers. Except for the 3 or 4 connections into the Taylor
system, these flows are routed directly to LeBlanc Drain in Allen Park.
The separate storm sewer system in Lincoln Park collects runoff from approx-
imately 1500 acres and routes this stormflow to LeBlanc Drain. Water from
LeBlanc Drain flows into the RDI through a connection which restricts flow to
17.2 cfs. During dry weather all flows enter the RDI and are treated by the
Wyandotte Plant. During wet weather the combined flows from Allen Park and
the storm flows from Lincoln Park and Taylor may exceed the 17.2 cfs and
overflow to Ecorse Creek. It is estimated that this will occur 17 times in
an average year.
The RDI conveys flows to the Wyandotte WWTP from Allen Park, Taylor, Lincoln
Park and several other communities. When flows in the RDI exceed the capa-
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city of the WWTP, excess flows are routed through District #5 pump station
along with combined sewage from Southgate and Wyandotte and receive primary
treatment for flows up to 520 cfs. Flows above 520 cfs are bypassed direct!v
to the Detroit River or are diverted to the Pine Street Pump Station and then
to the Detroit River. The Schematic Diagram of Flow illustrates this (See
Appendix for detail on excess flow routings.) *
The constraints on this system center around the capacity of the RDI which is
not defined at this time. The contracted capacity is 66.2 cfs. This is the
total arrount of flow which the RDI is contracted to convey to the WWWTP and
includes the 17.2 cfs contracted capacity for Allen Park. Estimates of the
flow capacity of the RDI range from 55 cfs to 150 cfs. The 55 cfs is the
/«J91 ???aciS "J^lated for the interceptor running at its designed level
(75% full). The 150 cfs is a capacity estimate for the interceptor based on
a calculated discharge of 115 cfs from LeBlanc Drain plus other estimated
concurrent flow. (See Appendix for a more detailed explanation.)
B. Approved Plan
The approved plan, Sewer Separation/Retention Basin, calls for the remainder
of the Ecorse Creek drainage area combined sewers in Allen Park to be
separated. Thereafter, sanitary sewage from Taylor, Allen Park and Lincoln
Park would be conveyed to the Wyandotte WWTP for treatment and discharge to
the Detroit River. s
A sanitary retention basin would be constructed under this plan to store
excess flows caused by infiltration and inflow from footing drains during wet
weather. This basin would be expected to overflow to the Sexton-Kilfoil
Drain periodically during severe conditions. All storm runoff would be
routed to LeBlanc Drain and discharged into Ecorse Creek. The connection
between LeBlanc Drain and the RDI would be eliminated. This operation is
Illustrated in the Approved Plan schematic.
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c*
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IV. Alternatives
The development and evaluation of alternatives began with a meeting on
03/24/83 among the concerned parties. The initial meeting included EPA,
MDNR, Allen Park, SEMCOG, Wayne County Drain Commissioner and consultants
or the agencies. The issues relating to the study and the many questions
surrounding previous studies were aired.
After analysis of the issues and separate discussions with Wayne County
Public Works, U.S. Army Corps of Engineers, and the consultants for the
Wyandotte-Southgate System, a second meeting was held on 04/06/83. This
meeting included EPA and consultants for EPA, the Wayne County Drain
Commissioner and Allen Park. The meeting resulted in identification of
two alternatives with the potential of meeting the Court's three criteria:
1) substantially less cost; 2) equal or better pollution loadings to
Ecorse Creek; and 3) able to be implemented within the time frame of the
currently approved plan.
Alternative 11 - Disconnect four Allen Park combined sewers that are con-
nected into the Taylor separate storm system and discharge the separate
stormwater to the Sexton-Kilfoil Drain (South Branch of Ecorse Creek) rather
than LeBlanc Drain. Maximize use of the existing inline storage capacity in
LeBlanc Drain through the use of inflatable dams. Introduce a maximum flow
of 115 cubic feet per second (cfs) into the River Drvve Interceptor from
LeBlanc Drain during wet weather.
Alternative 12 - Same as Alternative 11 but flow into the River Drive Inter-
ceptor from LeBlanc Drain would be limited to 17.2 cfs, Allen Park's pur-
chased capacity. (See schematics.)
The alternatives represent a possible range of flow accommodation capacity
in the River Drive Interceptor. The 17.2 cfs contribution is Allen Park's
purchased capacity. The 115 cfs is the calculated maximum flow from LeBlanc
Drain resulting in surcharged conditions in the River Drive Interceptor.
Two discharge location options were also identified:
A. Discharge of LeBlanc overflow into Ecorse Creek,
B. Discharge of LeBlanc Drain overflow into the Detroit River.
The basis of these alternatives is 1) the elimination of Taylor storm flows
from LeBlanc Drain creating greater capacity for inline storage of combined
sewage, and 2) the use of the River Drive Interceptor to transport sanitary
sewage and stormwater (combined sewage) to the Wyandotte Treatment Plant and
District #5 Facilities for treatment. It was thought that costs of implemen-
tation would be minimal, and the benefits in terms of reduced pollutant load-
ings would be comparable to the approved plan.
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CSC
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V. Analysis
A. Methodology
The alternatives were analyzed for cost, pollution abatement, and Institu-
tional Impacts. The results of the analysis were discussed at a third
meeting on 04/13/83 chaired by EPA and including representatives of MDNR,
Wayne County Drain Commissioner, Allen Park, the Corps of Engineers and
consultants for the agencies. At this meeting, issues relating to the cost,
benefits and implementation of the alternatives were discussed.
The benefits of the alternatives were analyzed through the use of the Storm
Water Management Model (SWMM). SWMM is the state-of-the-art in water quality
modeling and is accepted by the engineering and scientific community as the
best operational tool available for predicting pollutant loadings within com-
bined and separate storm sewer systems.
SWMM predicts the flows from a drainage area and the resulting loadings to
receiving waters. The model was initially verified based on preliminary data
obtained in April-May 1981. Further calibration and reverification of the
model was completed in April -June 1982.
The various input parameters within the model that were field measured for
quality and quantity included:
s
Dry weather flow for total LeBlanc Drainage District
Dry weather flow for Allen Park
* Dry weather flow for individual sub-catchment with
combined systems
* Dry weather flow for individual sub-catchment with
separate systems
* Infiltration for Taylor and Lincoln Park
* Combined sewer flow during wet weather for total
LeBlanc Drainage District
Five-day biochemical oxygen demand (BODs) was used as the best measure of
overall pollutant loadings to Ecorse Creek. Within the time frame available,
BODs in the model was calibrated, thus, enhancing the reliability of the
output.
B. Costs
The evaluation of costs of the alternatives involves two components: 1) cap-
ital costs comprising construction, engineering, contingencies, legal, ease-
ments, etc. and 2) operation and maintenance costs. Costs for Sewer Separa-
tion (approved Alternative) were taken from the Final Allen Park Retention
Basin and Pumping Facility Alternative Site Report prepared by Wade, Trim,
and Associates and dated June 7, 1982. O&M costs for Alternatives 11 and 12
Include: 1) operation and maintenance of facilities constructed (I.e. maximum
In-line storage, Detroit River discharge conduit), 2) excess flow charges
that would be levied to Allen Park by the Wyandotte WWTP for treatment and/or
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transport of flows above those expected under the Sewer Separation alterna-
tive, and 3) pumping costs for dewatering the Taylor retention basin into the
Sexton-KiIfoil Drain. Item 3, Taylor dewatering was based on existing
pumping capacity which would require approximately 200,000 kw hrs of power
annually to pump all storm water runoff and infiltration entering the Taylor
system. Power costs were estimated at $.05 per kw hr.
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ESTIMATED PROJECT COSTS
(1983 Dollars)
Total Amortized
Cost Items Capital Costs Capital Cost/yr
Alternative 11A (115 cfs to RDI, Discharge to Ecorse Creek)
Separation of Combined Lines
Currently Draining to Taylor $485,000 $ 48,000
In-L1ne Storage 400,000 40,000
Excess Flow Charges2
Pumping of Taylor Storm-
water to Sexton Kilfoil
TOTAL $885,000 $ 88,000
Alternative 118 (115 cfs to RDI, Discharge to Detroit River)
Separation of Combined Lines
Currently Draining to Taylor $485,000 $ 48,000
In-line Storage 400,000 40,000
Excess Flow Charges2
Pumping of Taylor Storm-
water to Sexton Kilfoil
Detroit River Discharge 6,000,000 594,000
TOTAL $6,885,000 $682,000
Alternative 12A (17.2 cfs to RDI, Discharge to Ecorse Creek)
Separation of Combined Lines
Currently Draining to Taylor $485,000 $ 48,000
In-line Storage 400,000 40,000
Excess Flow Charges2
Pumping of Taylor Storm-
water to Sexton-Kilfoil
TOTAL $885,000 $ 88,000
Alternative 12B (17.2 cfs to RDI, Discharge to Detroit River)
Separation of Combined Lines
Currently Draining to Taylor $485,000 $ 48,000
In-line Storage 400,000 40,000
Excess Flow Charges2
Pumping of Taylor Storm-
water
Detroit River Discharge 6,000,000 594,000
TOTAL $6,885,000 $682,000
Sewer Separation/Retention Basin
Sewer Separation $38,000,000 $3,763,000
Sanitary Sewage
Retention Pond 11,000,000 1,089,000
Engineering, Con-
tingency, etc. 10,000,000 990,000
$59,000,000 $5,842,000
1) 7 5/8% over 20 years
2\ Over and Above Those Levied Under Sewer Separation/Retention
3) Costs related to operation of each alternatives' components not
Annual
OMSR3
$ 30,000
103,000
10,000
$143,000
$ 30,000
103,000
10,000
10,000
$153,000
$ 30,000
60,000
10,000
$100,000
$ 30,000
60,000
10,000
10,000
$110,000
$ 51,900
67,400
$119,300
total annual
Total
Annual Cost
$ 48,000
70,000
103,000
10,000
$231,000
$ 48,000
70,000
103,000
10,000
604,000
$835,000
$ 48,000
70., 000
60,000
10,000
$188,000
$ 48,000
70,000
60,000
10,000
604,000
$792,000
$3,814,900
1,156,400
990,000
$5,961,300
sewage
treatment O&M.
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C. Benefits
The benefits of the alternatives were derived from the output of the SWMM
Model runs for the average rainfall year, 1965. These are shown in the fol-
lowing table and can be used for comparative purposes. Of particular import-
ance with respect to pollutant loadings to Ecorse Creek are the LeBlanc Drain
Overflow values for the alternatives and the LeBlanc Drain Stormwater Discharge
for the approved plan.
CSO ANALYSIS SWMM MODEL RESULTS
(1965 Storm Year)
Alternative 11 (115 cfs to RDI)
Flow Location
Combined Sewage to
River Drive Int.
LeBlanc Drain Over-
flow
Total Vol Ave Flow Events/ Hours/ average
(mil cu ft) (cfs) yr yr Concen.
102.00
22.00
32
1282 23.58
39.30 149.50 12
Alternative 12 (17.2 to RDI)
73
10.41
BOD Total
(Ibs/yr)
149,700
25,530
Combined Sewage to
River Drive Int.
LeBlanc Drain Over-
flow
54.50
11.80
32
1282 34.26
82.40 99.50 17 230 10.70
Sewer Separation/Retention Basin
116,600
55,020
Sanitary Sewage to
River Drive Int. 24.00 5.20
LeBlanc Drain Storm-
water Discharge 118.00 38.30
32
31
1282 79.25
858
8.79
118,900
64,780
Alternative 11 shows a 61% improvement in terms of fewer overflow events per
year and less BOD total annual loading over the approved plan, Sewer Separation.
Alternative 12 shows 45% fewer overflow events per year and 15% less BOD load-
Ing per year than the approved plan.
If Alternative 11 were implemented, the 115 cfs maximum CSO flow would be dis-
charged into the River Drive Interceptor where it would mix with the sanitary,
footing drain and combined flows of Ecorse, River Rouge, and Lincoln Park. At
the Wyandotte WWTP approximately 66 cfs of this mixture of flows would be given
secondary treatment based on the available capacity after plant expansion. The
remainder of this flow mixture would be treated by the District #5 facilities
where Jt would receive primary treatment or in severe storms would be over-
flowed without treatment to the Detroit River. The total capacity of District
#5 is 520 cfs, but the available capacity of the facilities to treat this flow
has not been determined.
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The pollutant strength of the flow mixture is, of course, dependent upon the
concentration of pollutants in each of the components (i.e.
Southgate/Wyandotte combined sewage, Allen Park combined sewage, sanitary flows
from Lincoln Park, Ecorse and River Rouge). In the event of a by-pass, evi-
dence suggests that BODs would be in the range of 80 mg/1 or less compared to
200 mg/1 for dry weather sanitary sewage.
Although not precisely defined, it is presumed from past operation of the
facilities (specifically before the 17.2 cfs restriction was installed at
LeBlanc Drain) that a substantial amount of this excess flow would be pro-
vided primary treatment by the District #5 facilities.
Under Alternative 12 (17.2 cfs to the RDI) the uncertainty of available capac-
ity in the District #5 facilities is not a problem since the contribution of
combined sewage to LeBlanc Drain would -not exceed Allen Park's contracted
capacity. As such, the entire flow entering the RDI would receive secondary
treatment prior to discharge to the Detroit River.
With Alternatives 11 (115 cfs to RDI) and 12 (17.2 cfs to RDI) the overflow of
dilute combined sewage to Ecorse Creek would occur 12 and 17 times respective-
ly in an average year compared to 31 discharges of stormwater with the approved
plan. Since the concentration of pollutants in the combined sewage is only
slightly greater than the concentration in the stormwater, the overall effect
is a greater annual loading of pollutants under the approved plan, 65,000
pounds BODs per year compared to 26,000 and 55,000 pounds per year for the
alternatives.
The water quality impact of a LeBlanc Drain combined sewer overflow discharge
into the lower Ecorse Creek, an average of 12 to 17 times per year has not been
determined. But, considering that the SWMM Model predicts average concentra-
tions of BOD in the 10 to 11 mg/1 range for this discharge and this is equiva-
lent to advanced waste treatment effluent, the impacts may not be as substan-
tial as previously thought. Also, considering that the primary use of this
stream is urban drainage and undetermined water quality problems are evident
upstream of LeBlanc Drain's discharge, other pollution sources appear to be
substantially responsible for the current water quality degradation in Ecorse
Creek.
The option of a Detroit River discharge would result in zero discharge of storm
and combined sewer overflows to Ecorse Creek from LeBlanc Drain. The pollution
loadings to the Detroit River would be as previously described for Alternatives
11 and 12, that is 26,000 and 55,000 pounds of BODs annually. The impact of
such loadings in the Detroit River would not be significant. Previous studies
on the combined sewer system in the City of Detroit and associated extensive
modeling of the Detroit River found that the Detroit CSOs contributed about 6.2
million pounds of BODs in an average year. By comparison, the LeBlanc
Drain's loading would be less than 1% of Detroit's CSO loading.
Although a Detroit River discharge remains an option, the benefits would not
result in significant enhancement of water quailty or the uses of Ecorse
Creek.
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D. Other Issues
1. Element III
Element III flood control facilities would not be significantly affected by
any of the three alternatives. Implementation of Alternative 11 or 12 would
convert LeBlanc Drain from a stormwater discharge to a dilute combined sewer
discharge. Since a portion of the flow would be intercepted by the River
Drive Interceptor, substantially less total volume would be discharged from
LeBlanc Drain than with the approved plan (Sewer Separation).
Under the selected Element III plan, retention basin C-l would provide treat-
ment for the North Branch Ecorse Creek, the Sexton-Kilfoil Drain and LeBlanc
Drain. With Alternatives 11 or 12, LeBlanc Drain would enter the basin
directly with its discharge of combined sewage. If this was not acceptable,
options would be an Ecorse Creek discharge for LeBlanc Drain upstream of the
C-l retention basin, or a Detroit River discharge for LeBlanc Drain. In any,
event, Element III is not an approved or funded plan and could be modified
accordingly to accommodate facilities implemented for Element II.
2. Wyandotte Plant and District #5 Facilities
The approved plan (Sewer Separation) and Alternative 12 would have little im-
pact on the Wyandotte plant operations since both alternatives use only up to
the allocated capacity purchased by Allen Park. Alternative 11 would not
significantly impact the Wyandotte Plant because flows entering the plant are
regulated so as not to exceed plant capacity, however, they may be somewhat
more dilute. Excess flows would be treated by the District #5 facilities and
during very severe storms would overflow without treatment to the Detroit
River from the District #5 pump station and/or the Pine Street pump station.
The available capacity of these relief points would be determined and
utilized with implementation of Alternative 11. The treatment and/or pumping
of these excess flows by the District #5 facilities is accounted for in the
excess flow charges listed in the Estimated Project Costs Table.
E. Implementation
1. Alternative of 17.2 cfs to RDI with CSO to Ecorse Creek or
Detroit River
a. This alternative assumes that the four combined sewers which currently
enter the Taylor Storm Sewer System would be separated. Thereafter, all
stormwater in Taylor would be stored in the two retention ponds and in-line
and would be discharged from the south retention pond to the Sexton-Kilfoil
Drain. The current 100 cfs dewatering flapgate to LeBlanc Drain would be
closed but would be retained and capable of being opened manually as an emer-
gency relief measure. Allen Park and Taylor would negotiate the loss of
Taylor's 100 cfs dewatering capacity in the LeBlanc Drain resulting in the
Increased pumping costs of stormwater from Taylor's south retention pond.
b. Once Taylor stormwater and infiltration are eliminated from LeBlanc
Drain, dry weather flows which will be totally treated by Wyandotte Plant
will consist of Allen Park sanitary flows, Allen Park footing drains and
infiltration and Lincoln Park infiltration. Wet weather flows in LeBlanc
Drain will consist of Allen Park sanitary, footing drain, infiltration and
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storm water plus Lincoln Park infiltration and stormwater. Allen Park and
Lincoln Park would negotiate the allocation of excess flow charges for flows
treated by the Wyandotte WWTP and charges for use of a Detroit River dis-
charge outfall if implemented.
c. Since Allen Park's current contract capacity in the RDI and the Wyandotte
WWTP would not be exceeded, no negotiations would be required concerning
additional capacity.
2. Alternative of Greater than 17.2 cfs to RDI with CSO to Ecorse
Creek or Detroit River
a. Same as a above.
b. Same as b above.
/-
c. Under this alternative, some capacity greater than the current contract
capacity of 17.2 cfs in the RDI would be required. The following steps would
be taken to obtain this capacity (Right to Deliver).
1. Allen Park City Council would file an official request
with the Wayne Co. to increase its contract capacity in
the RDI. This request would include documentation to
show that the requested capacity exists and is available
and that capacity exists at the downstream end to treat
and/or pump the additional flow. The County would notify
the Department of Public Works who would prepare an
engineering report and a legal report on the rights of all
communities involved. A recommendation would be made to
the County by the DPW.
11. All involved communities would be notified of the request.
The impact on each community would be described. Comments
would be made by the communities to the County.
111. On the basis of all information, opinions and recommenda-
tions, the County would decide on whether or not to grant
the Allen Park request for additional capacity in the RDI.
d. Also under this alternative, capacity for flows above the 17.2 cfs
treated by the Wyandotte WWTP would have to be acquired in the District #5
facilities. The following steps would be taken to obtain this capacity.
*
1. The Allen Park City Council would make an official request
for the capacity in the District #5 facilities to the South-
gate and Wyandotte Drainage Board. This request should be
accompanied by an engineering report which documents that
the requested capacity exists and is available as well as
the impact of additional flows on the operation and relia-
bility of the facilities.
11. A method and schedule of payment would also have to be nego-
tiated between Allen Park and the Southgate-Wyandotte Drain-
age Board to cover the costs of capital facilities and O&M
for the contracted capacity and flows.
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111. The cities of Southgate and Wyandotte would be notified of
the request and the impacts on. operation of the facilities
and costs. The position of each of the cities would be
obtained by the Board.
1v. A decision to grant or not grant the request would be made
by the Southgate-Wyandotte Drainage Board.
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VI. Implementation Steps
The following is a diagram of the steps required to implement alternatives 11
or 12. The durations of the steps which are provided are considered liberal.
Concurrent with these steps the negotiation of issues among communities (pre-
viously discussed) would take place. These negotiations would not affect the
time schedule.
IMPLEMENTATION NETWORK
Note:
3
3
3
3
3
3
3
3
3
90 days
Revise
Plans &
Specs
30 days
30 days
30 days
10 days
30 days
Request
Grant
Amendment
MDNR
Certification
Grant
Amendment
Advertise
For Bids
Receive
Bids
3
3 90 days
MDNR
Concurrence
Awa rd
Contract
1 Year
Construction
If start date "court order" is 05/11/83 then "construction" would
begin 03/19/84, two days before date required in 02/15/83 order.
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Subsequent to a decision by the court if either Alternative 11 or 12 were to
be implemented, the following would be required to complete the project.
Revise Plans and Specs (90 days)
The plans and specs must be revised to include the installation of
Inflatable dams, diversion of Taylor storm flows to Sexton-Kilfoil
Drain, modifications to overflow structures and separate the
combined sewer connections in Allen Park which drain to Taylor.
* Prepare Grant Amendment (30 days)
Concurrent with the plans and specs revisions the grantee would
prepare the paper work for a grant amendment request.
Amend FNSI ' (30 days) ^
EPA must prepare an amendment to the Finding of No Significant
Impact (FNSI). This task must be completed prior to MDNR cer-
tification of the request for grant amendment.
Request for Grant Amendment (30 days)
Upon completion of the plans and specs, the grant amendment would
be submitted for MDNR approval.
j
MDNR Certification (30 days)
MDNR must approve the grant amendment (State certification).
* Grant Amendment (30 days)
Following certification the grant will be amended.
Advertise Bids (10 days)
Following the grant amendment the grantee will advertise for bids.
Receive Bids (30 days)
Grantee will receive bids and provide MDNR with copy of the
bid prior to award.
MDNR Concurrence & Contract Award (90 days)
MDNR will concur with the bid award and the grantee will then
award the contract. If a start date for the above process is
assumed as 03/19/83, then the contract award would be 03/19/84.
This would be on schedule with the February 15 order which
states that the notice to proceed will be issued on or about
03/21/84.
* Construction (365 days)
If construction were begun on 03/19/84, then it would be completed
by 03/19/85. This is at least two years ahead of the scheduled com-
pletion of the sewer separation/retention basin plan.
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VII. Conclusions
Based on the analysis performed over the last several weeks, the USEPA has
concluded the following:
* The lower reaches of Ecorse Creek have little potential for
partial body contact uses. Therefore, water quality standards
for fecal coliform bacteria may not be appropriate, especially
'during wet weather.
* Five day biochemical oxygen demand is an appropriate measure of
pollutant loadings. '
* The pollution levels of Alternatives 11 and 12 would be lower than
the Sewer Separation/Retention Basin plan which is the currently
approved plan. This is possible because with the elimination of Tay-
lor stormwater from the LeBlanc Drain and the inline storage, the
alternatives allow an increased amount of stormwater and its pollu-
tant load to be treated. The Sewer Separation/Retention Basin pro-
vides no treatment of stormwater.
* The facilities and operational changes required for Alternatives 11
and 12 are easily implemented compared to the Sewer Separation/Reten-
tion Basin project. Construction could be completed substantially
sooner than Sewer Separation; possibly 2 years sooner.
* Alternative 11 and Alternative 12 would be substantially less
costly than the Sewer Separation/Retention Basin project (i.e.
$1 to $7 million vs. $59 million capital costs and $188,000 to
$835,000 vs. $6 million annual costs).
The Implementation of Alternative 12 does not preclude operation in
the Alternative 11 mode since both alternatives employ the same
facilities. The difference is only operational (i.e. 17.2 cfs to the
RDI for Alternative 12 or greater than 17.2 cfs, up to a maximum of
115 cfs to the RDI for Alternative 11). Some areas of uncertainty
which can be resolved after construction were identified relating to
Alternative 11. These included the available capacities of the River
Drive Interceptor, the Wyandotte Treatment Plant, the District #5
facility and the Pine Street Pump Station. These uncertainties do not
effect the implementation of Alternative 12.
A Detroit River outfall for LeBlanc Drain is not necessary con-
sidering the characteristics, current and probable future uses
of Ecorse Creek in its lower reaches upstream and downstream of
LeBlanc Drain.
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VIII. Recommendations
EPA makes the following recommendations:
1. Construct facilities recommended in Alternatives 11 or 12
with overflow to Ecorse Creek.
2. Determine the available capacity of the RDI, the Wyandotte
Treatment Plant, the District #5 Facility, and the Pine
Street Pump Station.
3. Determine costs, environmental impacts and benefits of
transporting and treating this flow.
x'
4. Reallocate costs to Allen Park for construction and operation
of facilities.
5. Modify the connection from LeBlanc Drain to the River Drive
Interceptor to allow increased flow.
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PI
To
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APPENDIX
28
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APPENDIX
Flow Routings
1. Flow routing in Taylor: After interviews and discussion with representa-
tives of Wayne County Drain Commission and Wade, Trim & Associates, the
following briefly describes the nature of the stormwater relief system in
Taylor in the context of the LeBlanc drainage basin.
Approximately 4200 acres of Taylor is tributary (directly or indirectly) to
LeBlanc Drain. Through a system of gravity stormwater interceptors flow
from 3200 acres is routed towards the Monroe Retention Basin. Initially,
flows "bypass" this retention basin and flow towards the junction chamber
at Pel ham and Champaign linking the Taylor system to the LeBlanc Drain. At
the same time, flow from the remaining 1000 acres flows to the junction
chamber. (The latter contains a combined sewage component from a small
portion of Allen Park which joins a 72" stormwater line running south along
Pelham Road.) Flow through the junction chamber is restricted to 100 cfs
(either from the Taylor flows or back pressure below the chamber). Flows
which cannot be accommodated in lines (a 60" corrugated line and a 30"
line) bypassing the retention basin, are routed to the Monroe retention
basin. After light rainfalls, this basin dewaters towards LeBlanc Drain.
Flows beyond the capability of this retention basin, LeBlanc Drain and
In-line storage are diverted to the south retention basin which borders the
Sexton-Kilfoil Drain. It is estimated that this retention basin receives
flow rarely (approximately 4 times/yr). Although originally designed to
automatically pump the majority of water to the Sexton-Kilfoil Drain, it is
not operated in that manner because of the "contamination" of the Taylor
stormwater by Allen Park's combined sewage. Instead, the retention basin
"floats" on the system. Flows which cannot be discharged to the LeBlanc
Drain or stored in other system components flow by gravity to the retention
basin, and then using the head developed, drain back to the LeBlanc system
when that system is capable of accepting it. Only the bottom 4 ft. of the
retention basin cannot flow back to the LeBlanc in this manner and must be
pumped to the Sexton-Kilfoil Drain. The amount of water involved is
approximately 16 million gallons. If it is assumed that water reaches this
basin 4 times each year approximately 64 million gallons (maximum) will be
pumped to Sexton-Kilfoil Drain.
2. River Driver Interceptor (RDI) Capacity: The major issue surrounding flow
routing or potential flow in the LeBlanc system is the capacity of the RDI
to accept flows from the LeBlanc Drain. The Wayne County Department of
Public Works has recently installed a flow restriction on this connection
limiting delivery of flows from the LeBlanc Drain to the RDI to 17.2 cfs.
This corresponds to the contracted amount that Allen Park maintains with
Wayne County for transport and treatment at the Wynadotte WWTP for flows
originating in the LeBlanc system. This occurs even though flows in the
LeBlanc Drain currently carry stormwater from Taylor and Lincoln Park in
addition to combined sewage flows from Allen Park. Actual capacity of the
pipe connecting the LeBlanc Drain to the RDI is approximately 115 cfs. The
Issue is not the capacity of this connection but rather the capacity of the
RDI to accept such flows. Estimates have varied from 55 cfs (Spaulding De
Decker) through 70 cfs (Wade, Trim) to more than 150 cfs (Williams &
Works). The differences can be traced to several factors associated with
calculation: 1) The amount of surcharging allowed. 2) The elevation used
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- ' for calculating head. The 55 cfs number is based on no surcharging and the
pipe running 75% full. The 70 cfs number was derived from water level
measurements in recorders upstream and downstream of LeBlanc Drain which
demonstrated surcharging of 2 1/2 to 4 ft., and actual elevation of the
Inverts of the RDI at those points. The 150 cfs number is derived by using
the head created between the bottom of LeBlanc Drain, elevation about 568'
(Indicating surcharging at that point of approximately 9 ft.) and the
Invert of the pipe as it enters the wet well of the Wyandotte WWTP plant.
Wade, Trim Associates developed, based on 150 cfs, a hydraulic gradient
showing surcharging above ground. This was based on an end point at the
junction chamber before the entrance to the Wyandotte WWTP rather than the
Invert of the pipe as it enters the wet well. Williams & Works calculation
of RDI capacity is somewhat reinforced by measurement during storms showing
that with a monitored peak flow entering the RDI, during overflows, without
flow restriction, the RDI was not surcharging as high as the invert of the
LeBlanc Drain. '
3. Flow Routing in Wayne County System Downstream of LeBlanc Drain.
Another major issue of concern is the capability of the system to accommo-
* date flows above the contracted amount of 17.2 cfs. (Disregarding at this
point the capacity of the RDI issue). RDI dry weather flows are routed to
the Wyandotte WWTP. Just prior to entering the WWTP the RDI joins
regulated flows from Southgate and Wyandotte. The other major source of
flows to the plant derives from the Downriver sanitary interceptor. During
^ wet weather, excessive flows from the RDI cause flows in the Downriver
V*. Interceptor to back up. In order to avoid basement flooding in the
Downriver service area, the plant operators restrict the flows from the
Southgate-Wyandotte- RDI service areas. This flow backs up in the inter-
ceptor and enters the District #5 pump station.
Pump station #5 has a capacity of 520 cfs and was constructed to treat or
by-pass flows from the Southgate/Wyandotte combined sewer area in lieu of
sewer separation. Any flows which exceeded the contracted amount for
Southgate/Wyandotte would enter Pump Station #5. Flows up to 520 cfs would
receive primary treatment while flows in excess of 520 cfs would be
discharged to the Detroit River. Under present conditions, this pump
station handles flow from Southgate/ Wyandotte and from the RDI service
area. Under extreme conditions, flows in the interceptor may back up, and
through a system of wier controls, enter the Pine Street Pump Station.
This Pump Station is designed for storm flows only but under the extreme
condition, it is actively discharging combined flows to the Detroit River.
The Wayne County Department of Public Works states that after improvements,
the Wyandotte plant will be able to accommodate a total of 242 cfs
comprising 31 cfs from District #5 (Southgate and Wyandotte regulated
flows) 144.7 cfs from Riverview and Pennsylvania Road interceptors and 66.2
cfs from the RDI (this includes the 17.2 cfs contracted amount from Allen
Park). If the RDI is carrying only 66.2 cfs, then the District #5 and Pine
Street Pump Stations will handle the flows as originally designed (i.e. no
excess RDI flows).
4. Storm Flows and Loads.
Average annual rainfall in the area is approximately 30 inches. Because of
the large tributary area to LeBlanc system, combined sewage from Allen Park
1s significantly diluted by the huge volume of relatively clean stormwater.
In addition, most, if not all of the homes in Allen Park have footing
30
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drains connected to the sewer line, and infiltration averages 50 gpcd in
the entire area (measurements of dry weather flow in LeBlanc Drain by
Williams 4 Works indicate an average of 12 cfs. Since sanitary flow from
Allen Park is only about 2.8 cfs, it is diluted almost fourfold by
relatively clean infiltration from Allen Park, Lincoln Park and Taylor).
This results in wet weather overflows with relatively low concentrations of
BOD. Samples of dry weather flow (sanitary sewage plus infiltration)
Indicate volumes averaging 12 cfs and BOD concentrations of 100 mg/1.
Samples of wet weather flow (sanitary sewage plus infiltration plus storm
water) in LeBlanc Drain showed BOD concentrations ranging from 30 to 80
mg/1. (All wet weather samples were taken at the beginning of overflow
events indicating that this was first flush quality. Storm water runoff
BOD concentrations ranged from 2.2 mg/1 to 14 mg/1.) This sampling of wet
weather flows confirms that the strength of combined sewage and overflows
from LeBlanc Drain are very dilute in terms of actual pollutant Concentra-
tions.
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