EPA-R2-72-070
October 1972
ENVIRONMENTAL PROTECTION TECHNOLOGY SERIES
Storage and Treatment of
Combined Sewer Overflows
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Office of Research and Monitoring
U.S. Environmental Protection Agency
Washington, D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were'established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
degradation from point and non-point sources of
pollution. This work provides the new or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards.
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EPA-R2-72-070
October 1972
STORAGE AND TREATMENT OF COMBINED SEWER OVERFLOWS
Project 11023
Project Officer
Clarence C. Oster
Lake Superior Basin Office - EPA
7^01 Lyndale Avenue
Minneapolis, Minnesota 55^55
Prepared for
OFFICE OF RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20^60
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402 - Price $2
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EPA Review Notice
This report has been reviewed by the
Environmental Protection Agency and
approved for publication. Approval
does not signify that the contents
necessarily reflect the views and
policies of the Environmental Pro-
tection Agency, nor does mention of
trade names or commercial products
constitute endorsement or recommen-
dation for use.
ii
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ABSTRACT
The objective of this study was to Demonstrate the feasibility
and economic effectiveness of a combined wastewater overflow
detention basin.
A paved asphalt detention basin with a storage volume of 8.66
acre feet was constructed at Chippewa Falls, Wisconsin to re-
ceive overflow from a 90 acre combined sewer area including all
of the central business district. The system was designed so
that the stored combined sewage could be pumped to the wastewater
treatment plant when precipitation subsided.
During 1969, due to dry weather, the pond received only sixteen
discharges, but completely filled twice and overflow to the river
occurred. During 1970, there were 46 discharges and the pond
filled once overflowing to the river. Over the two year period,
37.75 million gallons of combined sewage (93.7 per cent of the
total discharge volume) were withheld from the river for subsequent
treatment.
There were no observed detrimental effects on treatment plant oper-
ation due to the increased intermittent flows from the detention
pond. The estimated cost of operating and maintaining the pond
and associated facilities was $7,300 per year for the two year
period. Capital costs were $6,780 per acre of drainage area
including some relief combined sewer and increased size of units
at the wastewater treatment plant.
This report was submitted in fulfillment of Project No. 11023
FIY, under the partial sponsorship of the Environmental Protection
Agency.
iii
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CONTENTS
Section
I
II
III
IV
V
VI
VII
VIII
IX
X
Conclusions
Recommendations
Introduction
Design and Construction
Evaluation Plan
Results of Operation
Discussion of Results
Acknowledg ement s
References
Appendices
Page
1
3
5
9
25
37
85
99
101
103
v
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FIGURES
PAGE
1. Project Location Map 6
2. Mass Rainfall Curve 7
3. Storm Frequency - Intensity Graph 11
4. Three Point Hydrograph 12
5. Diversion Structure and Bay Street Pumping Station 14
6. Pumps in Bay Street Station 15
7. Discharge to Bay Street Station 16
8. Combined Sewage Pumping Station 17
9. Combined Sewage Pumping Station and Pond Drain Structure 17
10. Pond Drain Structure and Recording Rain Gage 18
11. Pond Overflow Structure 19
12. Pond Overflow Structure at High River Stage 19
13. Detention Basin Plan 20
14. Detention Basin During High River Stage 21
15. Detention Basin and Nearby Buildings 21
16. Wastewater Treatment Plant Flow Diagram 23
17. Recording Rain Gage 27
18. Palmer-Bowlus Flume 28
19. Liquid Level Recorder Enclosure 29
20. Liquid Level Recorder 30
21. Sampler Located in Wet Well of Combined Sewage Pumping Station 31
22. Upper Portion of Combined Sewage Sampler 32
23. Pond Drain Sampler 33
24. River Sampler Shelter 35
25. Storm of July 14, 1969 Hyetograph and Hydrograph 82
26. Storm of August 6, 1969 Hyetograph and Hydrograph 83
27. Storm of August 11, 1970 Hyetograph and Hydrograph 84
vi
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TABLES
No. Page
1. Labor Costs for Pond Cleaning 37
2. Labor Costs for Pond and Pumping Station Inspection 38
3. Pumping Costs Associated with Pond Operation 39
4. Added Cost of Treatment Plant Operation due to 40
Storm water.
5. Summarized Operation and Maintenance Costs 41
6. 1969 Combined Sewage Discharges - Volume and Duration 45-47
7. 1970 Combined Sewage Discharges - Volume and Duration 48-53
8. BOD^ and Suspended Solids for Combined Sewage Discharges 54-58
to Pond - 1969
9. BOD5 and Suspended Solids for Combined Sewage Discharges 59-65
to Pond - 1970
10. Settleable Solids, Volatile Suspended Solids and 66-67
Coliform Organisms - Average Values for 1969 Discharges
to Pond.
11. Settleable Solids, Volatile Suspended Solids, and 68-69
Coliform Organisms - Average Values for 1970 Discharges
to Pond.
12. Characteristics of Overflows to River. 70
13. 1970 Pond Drain Data 71
14. 1969 Wastewater Treatment Plant Data 72-75
15. 1970 Wastewater Treatment Plant Data 76-81
16. Treatment Effect of Pond During Overflows to River 87
17. Characteristics of the Chippewa River 89-96
vli
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SECTION I
CONCLUSIONS
1. During the two year study period 37.75 million gallons of
combined sewage (93.7 per cent of the total overflow volume)
were withheld from the river for subsequent treatment.
2. Of the 62 overflows to the pond, 59 were entirely withheld
from the river, and three resulted in pond overflows dis-
charging a small amount of combined sewage to the river.
3. During the study period, 49,520 pounds of BOD5 and 90,390
pounds of suspended solids were stored and later pumped to
the wastewater treatment plant. These loads represented
98.2 per cent of the total BOD^ and 95.8 per cent of the
total suspended solids contained in the overflows.
4. The estimated average operating and maintenance cost
attributed to the storage pond system was $7,300 per year.
The largest portion of this cost ($5430/yr.) was due to
the estimated increased cost of treatment plant operation.
5. The total capital cost for the demonstration project was
$610,067. This cost can be sub-divided into the following
components:
Detention Pond Construction $ 59,818.07
Pumping Station, Pond Structures & Piping $158,386.74
Combined Relief Sewer & Separate Sewers $222,937.73
Electrical Work $ 21,146.59
Treatment Plant Revisions $117,420.00
Engineering $ 28,857.99
Land $ 1,500.00
Total $610,067.12
6. At an interest rate of 6 per cent, the annual cost of
capital recovery over a 20 year period is $53,200. The
total annual cost under these conditions (including
operation and maintenance) is then $60,500.
7. The estimated capital cost for complete sewer separation
in the study area was $497,500.
8. The overflow detention basin stored combined sewage for
periods of up to fourteen hours without odors developing.
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9. Although it was located in close proximity to the central
business district, no complaints were received regarding
any phase of the pond operation.
10. A program of river sampling revealed no significant changes
in river quality which could be attributed to overflows
from the detention basin.
11. The average BOD,- of the combined sewage overflows was 150
mg/L, and the average suspended solids concentration was
280 mg/L.
12. The treatment effect of the pond was highly variable. The
BODc; and suspended solids removals normally expected from
primary sedimentation could not be attained consistently.
13. The increased duration of peak flows at the wastewater
treatment plant had no apparent detrimental effect on the
operation of the modified activated sludge plant.
14. Substantial relief from basement flooding in the downtown
area was attained as a result of the demonstration project.
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SECTION II
RECOMMENDATIONS
1. Storage followed by secondary treatment should be given
serious consideration as an alternative to complete
separation in areas served by combined sewers.
2. A major factor in determining the feasibility of storing
the overflows should be the existence of a suitable site
relative to the point of overflow and the location of the
wastewater treatment plant.
3. A site located in or near a developed area should not be
ruled out on this basis alone.
A. Careful analysis of the existing wastewater treatment plant
hydraulic capability should be undertaken in conjunction
with any investigation of overflow storage.
5. If it is possible that the treatment plant could become
overloaded due to increased peak hydraulic loads,
consideration should be given to returning the stored
overflows during off-peak periods only.
6. Future retention basins should have provisions for adequate
water for flushing the basin bottom after emptying.
7. Suitable access should be provided to the basin bottom for
street sweepers and trucks necessary to remove solids
accumulation.
8. Overflow to the basin should be regulated by an automatic
gate controlled by the depth of flow in the intercepting
sewer.
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SECTION III
INTRODUCTION
In 1966 the City of Chi^pewa.Falls, Wisconsin was under orders
from the State Regulatory Agency to provide separation of combined
sewers in the downtown area or to provide a method of treating
the combined wastewater overflows.
The City decided to investigate the feasibility of treating the
overflows and made application to the Federal Water Pollution
Control Administration for a Research and Development Grant
for this work as provided in the Clear Water Restoration Act
of 1966.
On December 23, 1966 the City was awarded an F.W.P.C.A. Research
and Development Grant (22-WIS-2) of $289,685 for preliminary
studies and reports, construction and engineering and post-
construction operations, studies and reports. This report was
prepared to make the findings of the project design, construction
and evaluation available in a form requested by the Federal Water
Pollution Control Administration.
In addition, the City made application for and received a 25 per
cent grant from the State of Wisconsin for preliminary studies and
reports and construction and engineering.
Construction of the project was started in October of 1967, and
was completed in March of 1969. The post-construction studies
and evaluations started on April 1, 1969, and concluded on
December 31, 1970. The post-construction studies and evaluations
were originally scheduled to be concluded on March 31, 1970, but
due to dry weather during the summer of 1969, an extension and
supplemental funding were requested. On March 30, 1970 a nine
month extension to December 31, 1970 and supplemental funding
of $15,000 or 75 per cent of the eligible costs, whichever is
less, was approved.
The project consisted of the construction and operation of a 75,000
gpm combined wastewater pumping station, 2.82 million gallon detention
pond, increased intercepting sewer pumping station capacity and
final settling tank capacity, combined relief sewer and some
separation.
The purpose of the project was to demonstrate that the combined
wastewater overflows could be retained for a period of time,
returned to the intercepting sewer and treated at a secondary
treatment plant. It was further intended that the storage and
treatment be accomplished without creating any nuisance conditions
and without disrupting the operation of the wastewater treatment
plant.
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SEPARATE B
STORM SEWER!
PROJECT LOCATION
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CO
¥
o
z
I
2-
0 20 40 60 80 100 120 140
TIME FROM BEGINNING OF STORM-MINUTES
FIGURE -2-
MASS RAINFALL CURVE
160 180 200
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SECTION IV
DESIGN AND CONSTRUCTION
The combined sewer tributary area selected for this project
consisted of ninety acres in the downtown area of Chippewa
Falls including all of the Central Business Distrct. This
area is tributary to the Bay Street pumping station which
discharges to the intercepting sewer leading to the waste-
water treatment plant. Prior to construction of the project
bypassing occurred to the Chippewa River through a 42 inch
corrugated metal pipe sewer whenever the capacity of the
Bay Street pumping station was exceeded.
The detention pond was located between the Bay Street pumping
station and the river in the area of the 42 inch outfall.
This site was the only feasible location for the pond. The
shape of the pond, which departed from the usual rectangle
or square, was dictated by site conditions. Figure 1 is
the project location map.
The total volume of rainfall which the pond was designed to
hold was determined from the mass rainfall curve for a ten
year storm less the theoretical percolation expected. Figure
2 is a plot of these curves.
From the curves, the maximum runoff for given conditions is
1.6 inches. The total volume of runoff from the ninety acre
tributary area was calculated as:
Vr = _R A
12
Where Vr is the volume of runoff in acre feet,
R is the runoff in inches and A is the area in
acres.
Vr = 1.6 x 90 = 12 Acre Feet
12
Similar calculations for theoretical runoff for a five year
storm would be about ten acre feet, and for a two year storm
would be about 7.5 acre feet. Figure 3 shows intensity as a
function of duration for storms of various expected frequencies
in the Chippewa Falls area.
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The total length of the design storm was calculated by using
a three point hydrograph as shown in Figure 4. The calculation
of Q Max, the peak rate of flow to the pond, was based on the
capacity of the combined relief sewer. This sewer capacity
was determined from the capacity of the tributary sewers rather
than from a theoretical calculation using the Rational Method.
This method of sizing was used to insure that "bottlenecks"
would not be created in the system to cause basement flooding
during rainstorms.
The peak rate of runoff from the design storm was taken as
164 cubic feet per second (cfs). The length of the design
storm was calculated as:
T = 24.2 Vr (2)
Q Max
Where T is the time in hours .Vr is the
volume of runoff in acre feet and Q Max
is the peak rate of runoff in cfs.
T = 24.2 (12) = 1 Hour 46 Minutes
164
The Bay Street pumping station formerly had a pumping capacity
of 4,000 gallons per minute (gpm), but the maximum rate that
could be conveyed by the force main and intercepting sewer was
6,000 gpm. The pumping capacity was therefore increased to
6,000 gpm. The estimated average dry weather flow was 2,000
gpm, so 4,000 gpm of combined wastewater could be pumped during
rainstorms without overflowing to the detention pond.
During the period of a design storm, the Bay Street pumping
station will deliver:
4,000 gpm x 106 Minutes = 424,000 Gal. = 1.3 Acre Feet
This represents the amount by which the total volume of runoff
could be reduced when calculating the size of the pond.
The design volume of the detention pond was 12.0-1.3 =
10.7 acre feet. The maximum design water depth was 7.7 feet.
Because of site restrictions imposed after the preliminary
design, the volume of the pond actually constructed was 8.66
acre feet. This volume is approximately equivalent to the
expected overflow from a five year storm.
10
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ro
200
cn 100
O
I
9
u.
a:
CO
PEAK FLOW 164 C.FS.= QMAX.
VOL OF RUNOFF = QMAX. T
2
T= LENGTH OF
STORM =! HOUR 46 MIN.
0 20 40 60 80 100
TIME FROM BEGINNING OF STORM - MINUTES
120
FIGURE -4-
3-POINT HYDROGRAPH
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Overflow to the pond occurs when the depth in a diversion
structure immediately upstream of the Bay Street station
exceeds a fixed elevation.
The elevation of the invert of the trunk sewers at the discharge
to the Bay Street pumping station is only 0.4 feet above normal
river level. Gravity flow to a retention pond could not be
obtained, hence a combined wastewater pumping station was designed
to pump all of the overflow to the pond. This station has a
capacity of 75,000 gpm which slightly exceeds Q Max.
The stored combined sewage and waste is returned to the Bay
Street pumping station by gravity through a regulating butter-
fly valve controlled by liquid level in the wet well of the
Bay Street Station.
Assuming a full pond and a maximum combined wastewater pumping
capacity of 4,000 gpm, and time to empty the pond is:
8.66 x 325,900 = 706 Minutes = 11 Hours 46 Minutes
4,000
The pond has a combination overflow and drain structure in the
dike on the river side. This structure provides for the over-
flow to the river when the total storm runoff to the pond exceeds
8.66 acre feet. In the event of power failure at the combined
wastewater pumping station or the Bay Street pumping station,
gates in the river overflow structure can be opened to allow
bypassing the pond contents to the river. Flap gates in the
combined wastewater pumping station allow emergency bypass flow
to go through the station without pumping.
Relief valves in the pond bottom were designed to prevent rupture
of the bottom during periods when the river level rises above the
pond bottom.
The pond walls were designed as earth dikes with 2:1 exterior
slopes and 3:1 interior slopes. The interior of the pond, top
of the dikes and the exterior of the dike on the river side
were paved with 2 inches of hot mix bituminous surfacing to
facilitate cleaning, and to allow vehicular traffic within the
pond for maintenance and grit removal. Riprap was specified
to cover the bituminous paving on the exterior of the dike on
the river side.
A watermain extension and fire hydrant were specified to be
located adjacent to the combined wastewater pumping station
for flushing of the pond bottom.
13
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X
Figure 5. Overflow diversion structure (foreground)
and Bay Street Pumping Station.
14
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Figure 6. Pump arrangement in Bay Street Station.
15
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Figure 7. 24 inch trunk sewer discharging to
Bay Street pumping station. Pumps
are protected by a hand-raked
bar screen.
16
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Figure 8. Combined sewage pumping
station viewed from pond.
;, -
Figure 9. Combined sewage pumping station
and pond drain structure.
17
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Figure 10. Pond drain structure and recording
rain gage.
18
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Figure 11. Pond overflow structure with
emergency bypass gates.
Figure 12. Pond overflow structure at high
river stage.
19
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m
RIVER J
SANs:
^
ST.
ARY PUMPING^-
DIVERSION STRUCTURE
VEHICLE GATE
JJTORM WATER
PUMPING
STATION
CX)UBLE
VEHICLE GATE
CHAIN LINK
FENCE
FIGURE-13-
DETENSION BASIN PLAN
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Figure 14. Detention basin during high
river stage.
Figure 15. View of pond in winter showing
proximity of business district.
21
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The design of additions to the wastewater treatment plant was
being done at the same time as the design of the detention basin.
These additions provided for secondary treatment.
The wastewater treatment plant is an activated sludge plant
capable of being operated as conventional activated sludge,
contact stabilization or step aeration. The plant is designed
for an average DWF of 3.2 MGD for waste with characteristics
of 320 mg/L (8,500 pounds) BOD5 and 280 mg/L (7,500 pounds)
suspended solids. The maximum flow that can be taken through
the plant is 14.11 MGD or 9,800 gpm which is the capacity of
the intercepting sewers entering the plant.
The four aeration tanks were designed on the basis of 50 pounds
of 5 day BOD per day per 1,000 cubic feet of volume. The two
final settling tanks are 65 feet diameter peripheral feed tanks
sized on the basis of 3.2 MGD average DWF plus 4,000 gpm of
combined wastewater from the retention pond.
The final tanks were increased in size from a diameter of 45
feet to 65 feet because the greater length of time at high
flows (9 MGD for over 14 hours) would tend to flush the activated
sludge out of the smaller tanks. Normally, the peak intercepting
sewer flow (14 MGD) would occur for only a short period of time
and this would not adversely affect the plant.
The construction of the project was divided into four divisions
identified as A, B, C and D. Division A was the construction
of the detention pond, including grading, paving, riprap, fence
and landscaping; Division B was the construction of the
combined wastewater pumping station, detention pond structures,
piping and Bay Street pump station modifications; Division C
was the construction of the combined relief sewer and some
separate sewers; Division D was the electrical work on the
project.
The final contract amounts were as follows:
DIVISION A $ 59,818.07
DIVISION B $158,386.74
DIVISION C $222,937.73
DIVISION D $ 21,146.59
SUB-TOTAL $462,289.13
TREATMENT PLANT EXPANSION $117,420.00
(Attributable to Demonstration Project)
ENGINEERING $ 28,857.99
LAND $ l^OOJOO
TOTAL PROJECT COST $610,067.12
22
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MECHANICALLY RAKED
BAR SCREEN
GRIT REMOVAL
CHAMBER
' RAW SEWAGE FROM
{COLLECTION SYSTEM
FLOW METER
d
Ul
to
^
1
/
FLOCCULATION
TANK
PRIMARY SETTLING
TANKS j
CHLORINE CONTACT
TANK
f WASTE SLUDGE
j RETURN /
"1
FINAL SETTLING
AERATION
TANKS
RETURN ACTIVATED
SLUDGE
SLUDGE
TO DIGESTERS
RAW SEWAGE
PUMPS
SUPERNATANT
TO TREATMENT PROCESS
X.DIGESTED SLUDGE"
TO DRYING BEDS
a DISPOSAL
RETURN ACTIVATED
SLUDGE
TREATED EFFLUENT
TO RIVER
FIGURE -16-
WASTE WATER TREATMENT PLANT — FLOW DIAGRAM
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Project construction began in October of 1967 and was completed
and accepted by the City in March of 1969.
No unusual construction problems were encountered. The pond
paving subcontractor experienced no difficulty in paving the
slopes of the pond sites.
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SECTION V
EVALUATION PLAN
For a meaningful evaluation of the storage pond as a method
of controlling combined sewage overflows, a considerable
amount of information was required. Equipment was installed
at the pond site in order to provide the following data:
Rainfall - Time Rate and Total
Discharge to Pond - Time Rate
Volume
Characteristics
Overflow from Pond to
River - Time Rate
Volume
Characteristics
The rainfall was measured by a Belfort Instrument Company Catalog
No. 5-780 Universal Recording Rain Gage with 4.8 inch capacity
(dual traverse) and six hour time scale charts. The rain gage
was located on the top of the pond drain structure.
The overflow from the Bay Street station diversion structure to
the pond was measured by a Palmer-Bowlus flume installed in a 78
inch reinforced concrete pipe. The flume was designed as outlined
by Wells and Gotaas (1), fabricated of steel pipe, and installed
in the pipe as it was laid. The space between the flume and pipe
was grouted.
A tee section manhole just upstream of the flume area was used for
access to measure the head on the flume. A scow float was installed
in the pipe and a Stevens Type A 35 water-level recorder was
installed at the ground surface to measure the water level. A
rating curve for the flume was calculated as outlined by Ludwig
& Ludwig (2). The water level was measured and the rating curve
was used to develop the hydrograph rather than a direct flow
measurement in gpni or cfs because of the wide range of flows
expected (0 to 75,000 gpm). The chart time scale was 28.8 inches
per day and the gage scale was 1.6 (1 foot on the chart equals
6 feet of level fluctuation.)
The discharge to the pond was sampled in the wet well of the
combined wastewater pumping station by a SERCO automatic sampler
which took a discrete sample every five minutes for two hours.
The sampler was equipped with an automatic float starter activated
by a rising water level in the wet well of the combined wastewater
pumping station.
25
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The overflow from the pond to the river was measured by a
22 foot long sharp crested weir located in the overflow
structure. The weir head was measured by a Stevens Type
A-35 water-level recorder with a cylindrical float. The
chart time scale was 9.6 inches per day and the gage scale
was 1:6.
The overflow to the river was sampled by a SERCO automatic
sampler located at the overflow structure. A discrete sample
was taken every sixty minutes during overflows for up to
twenty-four hours. This sampler also was equipped with an
automatic float starter activated by rising pond level.
The dissolved oxygen readings were taken with a Weston
& Stack Dissolved Oxygen Analyzer Model 300 B with agitator
probe.
In May of 1970, at the suggestion of the Demonstration
Project Review Committee, a sampler was installed in the
pond drain structure. The samples were taken from the
pond drain line at 10 minute intervals and composited
automatically in equal volumes.
All samples were analyzed for five day BOD, suspended
solids, volatile suspended solids, settleable solids, and
fecal and total coliform organisms. The analyses were
performed at the wastewater treatment plant laboratory
which is certified by the State of Wisconsin Department of
Natural Resources. All procedures were taken from Standard
Methods for the Examination of Water and Wastewater (3).
It was found that the sample volumes for the settleable
solids determinations were often too small for the standard
Imhoff cone test. Therefore, an alternative technique was
used in which the samples were allowed to settle for an
hour, and suspended solids were determined on the super-
natant. Settleable solids were obtained by subtracting
the supernatant suspended solids from the total suspended
solids concentration. Results were then reported as mg/L
rather than the usual ml/L. The major disadvantage to this
procedure was that most of the floatable solid material
was included in the results as settleable solids. The
data could thus be more correctly labeled as settleable
plus floatable solids.
The membrane filter technique was used in determining the
most probable number of coliform organisms.
26
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Figure 17. Rain gage at pond site.
27
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Figure 18. Palmer-Bowlus flume and
scow float used to measure
combined sewage discharge.
28
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Figure 19. Enclosure for liquid level
recorder above tee section manhole.
29
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Figure 20. Liquid level strip chart
recorder.
30
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Figure 21. SERCO sampler in wet well
of combined sewage pumping
station.
31
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Figure 22. Sampling apparatus at upper level
of combined sewage pumping station.
32
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Figure 23. Automatic sampler at pond
drain structure.
33
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The volume discharged into the pond during each overflow was
determined from the recorded head on the Palmer-Bowlus flume.
In the computations, the rating curve for the flume was
approximated by four linear sections. The liquid level data
could then be converted directly into flow data. BOD^ and
suspended solids loads were calculated using the average
concentration and the total volume for each discharge. This
method minimized the effect of any single non-representative
sample, and it was felt to be at least as accurate as the more
involved technique of calculating a load for each five-minute
interval based on the individual grab sample for that interval.
Fewer individual samples were available from the pond overflows
to the river since the time interval for sampling was 60
minutes rather than 5 minutes. Discharge volumes were com-
puted from the recorded head on the sharp crested weir, and
loads were again determined using average concentrations.
In order to determine any possible effect of pond operation
on the quality of the Chippewa River, a river sampling and
testing program was undertaken. The river was sampled at
two locations - one at Bridge Street, upstream from the
detention pond, and one at Main Street, downstream from the
pond but above the sewage treatment plant. Samples were
generally taken on a weekly basis throughout the study
period. The following analyses were performed on the samples:
Settleable Solids
Suspended Solids
Suspended Volatile Solids
Fecal Coliform Organisms
Total Coliform Organisms
5-Day BOD
Dissolved Oxygen
Temperature
PH
A visual check was also made at the time of sampling to
determine if any floating material was present in the river.
• 34
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Figure 24. River sampler shelter at
pond overflow structure.
35
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SECTION VI
RESULTS OF OPERATION
The pond has been operating since April 1, 1969 with the first
bypass to the pond occurring on April 20, 1969. After each bypass
the pond was cleaned either using a fire hose or a street sweeper.
The labor and associated costs for pond cleaning were as follows:
TABLE 1
MONTHLY LABOR COSTS FOR POND CLEANING
Month Labor (Man Hours) Cost
April 1969
May
June
July
August
October
May 1970
June
July
August
September
15
3 street
21
35-1/3
18
10
28
44
48
144 (18 C.Y
82
$ 47.40
sweeper $ 51.00
$ 66.40
$ 112.00
$ 56.80
$ 31.60
$ 88.50
$ 139.00
$ 152.00
. sand removal )$ 455.00
$ 259.00
TOTAL $1,454.70
1969 $ 365.20
1970 $1,089.50
Experience showed that the quickest and most economical means of
cleaning settled solids from the pond was using a street sweeper.
However, availability of the unit and operator was sometimes a
problem. A total of 207,000 gallons of water in 1969 and 234,000
gallons in 1970 were used for pond flushing and cleanup. At the
Chippewa Falls water rates, the costs for cleaning water during
1969 and 1970 were $55.30 and $62.40 respectively. In addition
to the labor involved in cleaning operations, daily checks of the
pond were made during the regular inspection of the Bay Street
pumping station. The labor attributed to checking the pond is
tabulated by month as follows:
37
-------
TABLE 2
MONTHLY LABOR COSTS FQR POND AND PUMPING STATION INSPECTION
Month Hours , Cost
April 1969 10 Hr. 40 Min. $ 33.70
May 10 Hr. 10 Min. $ 32.10
June 10 Hr. 55 Min. $ 34.50
July 11 Hr. 45 Min. $ 37.10
August 13 Hr. 15 Min. $ 40.80
September 12 Hr. 10 Min. $ 38.40
October 12 Hr. $ 37.90
November 13 Hr. 20 Min. $ 42.20
December 13 Hr. 20 Min. $ 42.20
TOTAL 107 Hr. 35 Min. $338.90
April 1970 20 Hr. 50 Min. $ 66.20
May 23 Hr. 30 Min. $ 73.60
June 28 Hr. 15 Min. $ 89.30
July 30 Hr. 15 Min. $ 98.80
August 27 Hr. $ 85.30
September 26 Hr. 45 Min. $ 84.50
October 27 Hr. 55 Min. $ 88.30
November 26 Hr. $ 82.20
December 28 Hr. 10 Min. $ 88.80
TOTAL 238 Hr. 40 Min. $757.00
These costs are undoubtedly inflated somewhat because of the added
attention given to the sampling equipment and instrumentation used
in the demonstration study. Furthermore, a significant portion
of the daily inspection time was for the check of the Bay Street
pumping station, which would have been necessary with or without
the presence of the storage pond.
In addition to cleaning and daily inspection, the operating costs
attributable to the pond system include the cost of pumping the
combined wastewater to the pond and the added pumping and treatment
costs due to the stormwater which is collected by the combined
sewer system. These are costs which would not have been incurred if
complete sewer separation had been accomplished. The total runoff
for the drainage area was estimated from the rainfall data for
1969 and 1970 by assuming an average percolation of 20 per cent of the
total volume of rainfall. By subtracting the volume which overflowed
to the river from the total runoff, one can estimate the additional
38
-------
pumpage at the Bay Street station due to the storage pond system.
To obtain the total pumpage, the volume which overflowed to the
pond (and was pumped by the combined sewage pumping station) must
be added. These figures plus associated power costs are tabulated
as follows:
TABLE 3
PUMPING COSTS ASSOCIATED WITH POND OPERATION
1969 1970
Total Runoff 35.7 Mgal. 59.4 Mgal.
Total Overflow to River 1.03 Mgal. 1.52 Mgal.
Net Volume Pumped By 34.7 Mgal. 57.9 Mgal.
Bay Street Station
Energy Used 11,700 Kwh. 19,600 Kwh.
Power Cost $368 $618
Total Discharge to Pond (pumped 13.8 Mgal. 26.5 Mgal.
by combined sewage pumping
station)
Energy Used 722 Kwh. 1,390 Kwh.
Power Cost $ 23 $ 44
Total Power Cost for Pumping $391 $662
(excluding sewage treatment plant)
The cost of treating the additional stormwater is difficult to dis-
tinguish from the total cost of operation for the treatment plant.
An idea of the magnitude of this cost may be determined as a percent-
age of the total operating cost by assuming that the cost of treatment
is proportional to the flow. This method will probably result'in a
value somewhat higher than the actual cost since the average organic
and solids concentrations in the stormwater are lower than in the
sanitary sewage and wastes. Nevertheless, such figures may be useful
as conservative estimates of the cost of operating this type of system.
39
-------
TABLE 4
Added Cost of Treatment Plant Operation Due to Stormwater
1969 1970
Total Wastewater Flow (millions 809.891 820.886
of gallons)
Total Stormwater to Plant 34.7 57.9
(millions of gallons)
(Storm Volume ) inn"/ 4.3% 7.1%
—. . X ±.\J\J/o
(Wastewater Volume )
Total Operating & Maintenance Cost $90,211 $98,395
Operating & Maintenance Cost
Associated with Stormwater $ 3,880 $ 6,980
The approximate total cost of operating and maintaining the pond
system can be summarised as follows:
40
-------
TABLE 5
SUMMARIZED OPERATION AND MAINTENANCE COSTS
PUMPING (EXCLUDING PUMPS IN
TREATMENT PLANT)
ADDED COST OF TREATMENT
PLANT OPERATION
POND CLEANING AND MAINTENANCE
1969
$ 391
$3,880
$ 759
1970
$ 662
TOTAL OPERATION AND MAINTENANCE COST $5,030
$9,551
As might be expected, the operating cost of the retention pond system
is dependent to a large extent on the amount of rainfall in the
drainage area. During the 1970 test period, 30.43 inches of rainfall
were recorded, and the cost of operation was approximately twice the
cost of that for 1969 when only 18.25 inches of rainfall were recorded.
It should further be noted that the largest portion of the operation
and maintenance cost is due to the increase in hydraulic load at the
sewage treatment plant. This is also the least accurate and most
difficult to determine of all the costs associated with the pond
operation.
Throughout the course of the study, there were no objectionable
odors reported from the pond vicinity either during overflow of
cleanup periods.
The river reached a high water elevation of 827.4 during the spring
of 1969. This water level was 0.6 feet below the top of the dike,
but 0.4 feet above the flood control gates. As a result, an
undetermined volume of river water entered the pond. There was no
apparent ill effect from the high water.
Two minor operational problems were noted as follows:
1. The wet well of the combined wastewater pumping
station had a grating cover over the top. In the
winter, snow entered the wet well, partially melted,
and formed ice in the wet well. This was corrected
by covering the grating with plywood in the winter
and placing a heat lamp over the wet well sump pump.
41
-------
2. The grit chamber area on the discharge of the
combined wastewater pumps should have been deeper
to retain more grit and to keep the snow and ice
below the emergency station bypass flap gates.
From April 1, 1969 to December 31, 1970, rainfall was recorded at
the pond site on 129 days. On 62 of these days combined sewage
discharged to the storage pond, and on three occasions the pond
overflowed to the river. Tables 6 and 7 show the rainfall data
together .with the duration and volume of each discharge to the
pond during 1969 and 1970. The BOD and suspended solids data
from the discharge samples are given in Tables 8 and 9. During
certain discharges, the sampling apparatus was not functioning
properly and as a result, the data are not complete.
The values for settleable solids, suspended volatile solids,
fecal and total coliform organisms are averaged for each dis-
charge and tabulated in Tables 10 and 11. The three overflows
from the pond to the river are described in Table 12. Hourly
samples were collected and analyzed for the duration of each
pond overflow. However, the liquid level recorder at the
overflow structure was out of service during the storm of ,
August 6, 1969, and no discharge data is available for this
overflow. The volume discharged to the river has been
estimated however, by subtracting the pond storage volume
from the volume discharged into the pond.
Table 13 is a compilation of the, characteristics of the combined
sewage as it drained out of the pond and back to the Bay Street
pumping station. The sampler at the pond drain was installed
in May 1970 and operated continuously, taking a sample every
10 minutes whenever there was flow through the drain line.
The individual samples were combined in equal volumes and
thus were not composited according to flow.
The influent and effluent 6005 and suspended solids data for
the wastewater treatment plant are shown in Tables 14 and 15.:
Routine collection and compositing of BOD samples was done
every third day only. Hence, sampling did not always occur
on days of precipitation. The influent BOD and suspended
solids values are artificially ,high since the samples were
taken at a point following the addition of the digester
supernatant and the waste activated sludge. The reported
removal percentages are, therefore, somewhat higher than
the actual removals. Detailed operating data for the treat-
ment plant Curing-1969 and 1970 are summarized in the Appendix.
The relatively poor effluent quality in April and early May
of 1969 was due to operational difficulties with the return
activated sludge pumps.
42
-------
During the period from January 1, 1970 =to December 31, 1970,
six different flow configurations were used in the aeration
portion of the wastewater treatment plant. However, the
effluent quality remainder fairly constant during the dry
weather period from January through March.
Based on previous pumping records, the average dry weather
sewage and wastewater flow to the Bay Street pumping station
is approximately 2000 gallons per minute or 2.88 mgd. Grab
samples of the wastewater entering the pumping station during
dry weather conditions have shown BOD values of 468 mg/L on
a weekday and 296 mg/L on a weekend. The difference can be
attributed to the industrial BOD load which is considerably
greater on weekdays than on weekends. The major industrial
loads are contributed by a meat packing plant, a creamery,
a brewery and two plastic factories. However, the meat packing
plant does not discharge to the portion of the sewage collection
system tributary to the Bay Street pumping station.
Figures 25, 26 and 27 are rainfall'hyetographs and hydrographs of
of the discharge to the pond during the July 14 and August 6,
1969 and August 11, 1970 storms, respectively. These are
plotted in five minute intervals.
The rainfall on July 14, 1969 began at 5:35 a.m. Discharge to
the pond began at 5:38 a.m. The Bay Street station was dis-
charging its capacity of 6,000 gpm (13.4 cfs) about two minutes
after the discharge to the pond began or about 5:40 a.m. The
pond discharge hydrograph peak must be increased by 9 cfs to obtain
the total runoff hydrograph peak of 138 cfs because 9 cfs of runoff
was pumped by the Bay Street station during the storm, the
total volume which discharged to the river, as pond overflow,
was 615,000 gallons.
The rainfall on August 6, 1969 began at 9:48 p.m. Discharge to
the pond began at 9:55 p.m., and the Bay Street station again
was handling its maximum capacity of 6,000 gpm (13.4 cfs) about
two minutes after discharge to the pond began or about 9:57 p.m.
The combined sewage discharge hydrograph peak of 168 cfs was reached
at 10:10 p.m. or 22 minutes after rainfall began. The total runoff
hydrograph peak was 177 cfs, and the overflow to the river was
estimated to be 412,000 gallons.
The rainfall on August 11, 1970 began at 2:35 p.m. Discharge to
the pond began at 2:47 p.m. The Bay Street station was pumping
its capacity of 6,000 gpm (13.4 cfs) about one minute after
discharge to the pond began or about 2:48 p.m. The hydrograph
peak for-discharge to the pond of 164 cfs was reached at 3:05 p.m.
or thirty minutes after rainfall began. The total runoff hydrograph
peak was 174 cfs, and total overflow to the river was 1,523,000
43
-------
gallons. The July 14, 1969 storm had a rainfall intensity
of 3.25 inches per hour for the first twelve minutes and the
August 6, 1969 storm had a rainfall intensity of 3.0 inches
per hour for the first twenty-two minutes. The August 11, 1970
storm had a rainfall intensity of 2.48 inches per hour for the
first thirty minutes.
Using the Rational Formula, C (runoff coefficient)may be cal-
culated as follows:
JULY 14, 1969 Q = CIA
138 = C 3.25 (90)
C = 0.47
AUGUST 6, 1969 Q = CIA
177 = C 3.0 (90)
C = 0.65
AUGUST 11, 1970 Q = CIA
174 = C 2.48 (90)
C = 0.78
The value of "C" appears to increase with an increase in the length
of time between beginning of rainfall and peak flow on the hydrograph.
This is consistent with studies which have shown an increase in the
"C" factor with an increase in the duration of rain.
The pond D.O. was checked after the April 27, 1969 storm. Discharge
to the pond started at 12:42 a.m. and ended at 2:07 a.m. The
lowest D.O. was 0.8 mg/L near the river overflow structure at
10:00 a.m. The pond D.O. was again checked after the September
21, 1970 storm. Discharge to the pond began at 5:10 a.m and ended
at 9:45 a.m. The lowest D.O. was 6.4 mg/L on the north side of the
pond at 9:00 a.m.
44
-------
TABLE 6
1969 COMBINED SEWAGE DISCHARGES - VOLUME AND DURATION
DATE
APRIL 8
APRIL 9
APRIL 14
APRIL 20
APRIL 26
APRIL 27
MAY 1
MAY 2
MAY 5
MAY 6
MAY 10
MAY 17
MAY 19
MAY 21
MAY 26
MAY 31
PRECIPITATION
(inches)
0.07
-
.14
.20
.13
.48
.81
-
.05
.17
.02
.66
.22
.12
.10
.21
VOLUME OF
DURATION DISCHARGE
OF DISCHARGE TO POND
TO POND (cu. ft.)
_ _
12:04 A.M. - 1:25 A.M. 27,700
-
8:53 A.M. - 10:30 A.M. 24,100
-
12:42 A.M. - 2:07 A.M. 23,600
2:58 A.M. - 4:25 A.M. 2,900
1:45 P.M. - 2:27 P.M. 1,700
6:25 A.M. - 7:25 A.M. 11,600
12:58 P.M. - 1:38 P.M. 4,500
12:56 A.M. - 3:12 A.M. 71,900
-
-
-
-
-
-
1:04 A.M. - 1:18 A.M. 3,800
7:41 P.M. - 9:02 P.M. 32,200
45
-------
TABLE 6 (Continued)
1969 COMBINED SEWAGE DISCHARGES - VOLUME AND DURATION
PRECIPITATION
DATE (inches)
JUNE
JUNE
JUNE
JUNE
JUNE
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
JULY
11
12
22
25
26
2
4
8
14
24
25
26
28
30
.88
.53
.48
.68
.62
.69
.15
1.01
2.53
.03
-
.24
-
.23
DURATION
OF DISCHARGE
TO POND
4:00 A.M.
7:38 A.M.
5:30 A.M.
4:35 P.M.
10:30 A.M.
5:22 A.M.
8:25 A.M.
9:00 A.M.
5:38 A.M.
8:30 A.M.
11:33 P.M.
1:35 P.M.
10:20 P.M.
- 6:50 A.M.
- 1:00 P.M.
- 7:50 A.M.
- 6:40 P.M.
- 1:50 P.M.
-
- 7:17 A.M.
- 9:15 A.M.
- 11:35 A.M.
- 9:22 A.M.
-
- 1:10 P.M.
- 9:40 A.M.
- 2:45 P.M.
- 11:00 P.M.
VOLUME OF
DISCHARGE
TO POND
(cu. ft.)
RECORDER
OUT
OF
ORDER
-
155,800
11,000
191,200
499,400
-
9,500
65,700
8,700
7,200
46
-------
TABLE 6 (Continued)
1969 COMBINED SEWAGE DISCHARGES - VOLUME AND DURATION
PRECIPITATION
DATE (inches)
AUG.
AUG.
SEPT.
SEPT.
SEPT.
SEPT.
OCT.
OCT.
OCT.
OCT.
OCT.
OCT.
OCT.
OCT.
NOV.
NOV.
6
29
4
22
25
29
1
5
12
15
16
19
30
31
1
17
.40
1.97
.14
.18
.36
.22
.15
.22
.30
.20
.78
.46
.02
.10
.46
.28
.08
.48
VOLUME OF
DURATION DISCHARGE
OF DISCHARGE TO POND
TO POND (cu. ft.)
9:48 A.M. - 10:25 A.M. 90,000
9:55 P.M. - 12:45 A.M. 432,000
_
3:42 P.M. - 4:40 P.M. 12,900
8:00 P.M. - 8:50 P.M. 6,100
5:05 P.M. - 8:00 P.M. 37,500
-
1:05 A.M. - 3:10 A.M. 13,900
2:55 A.M. - 3:45 A.M. 11,200
8:08 P.M. - 9:38 P.M. 13,900
-
9:17 P.M. - 1:35 A.M. 32,700
-
-
-
8:10 P.M. 10:15 P.M. 7,800
4:42 P.M. - 6:17 P.M. 7,700
-
4:57 P.M. - 7:42 P.M. 31,800
47
-------
TABLE 7
1970 COMBINED SEWAGE DISCHARGES - VOLUME AND DURATION
DATE
APRIL 5
APRIL 12
APRIL 15
APRIL 19
APRIL 20
APRIL 22
APRIL 23
APRIL 28
APRIL 30
MAY 1
MAY 9
MAY 11
MAY 12
MAY 13
MAY 14
MAY 19
PRECIPITATION
(inches)
0.14
.08
.12
.77
.10
.06
.11
.04
.06
.06
.08
.56
-
.27
.41
.52
.03
VOLUME OF
DURATION DISCHARGE
OF DISCHARGE TO POND
TO POND (cu. ft.)
_ —
-
-
3:20 P.M. - 11:20 P.M. 58,300
-
5:45 P.M. - 6:30 P.M. 6,200
-
-
-
.
9:25 A.M. - 10:55 A.M. 86,400
11:10 A.M. - 11:50 A.M. 4,800
1:20 A.M. - 2:05 A.M. 23,700
10:45 P.M. - 12:15 A.M. 6,100
1:32 A,M. - 3:02 A.M. 13,400
48
-------
TABLE 7 (Continued)
1970 COMBINED SEWAGE DISCHARGES - VOLUME AND DURATION
PRECIPITATION
DATE (inches)
MAY 21
MAY 22
MAY 23
MAY 24
MAY 25
MAY 27
MAY 28
MAY 29
MAY 30
MAY 31
JUNE 9
JUNE 11
JUNE 12
JUNE 13
JUNE 15
JUNE 16
.47
.50
.06
.08
.10
.72
.48
.04
.26
.42
.06
.22
.17
.08
.68
.02
VOLUME OF
DURATION DISCHARGE
OF DISCHARGE TO POND
TO POND (cu. ft.)
6:50 P.M. - 7:05 P.M. 1,200
10:45 P.M. - 12:25 A.M. 40,000
1:10 A.M. - 2:55 A.M. 46,200
4:40 A.M. - 7:55 A.M. 100,200
-
-
-
11:12 P.M. - 12:00 A.M. 23,700
12:00 A.M. - 3:55 A.M. 109,500
-
1:05 A.M. - 3:20 A.M. 10,700
8:15 A.M. - 1:55 P.M. 109,700
-
7:10 P.M. - 7:55 P.M. 27,100
5:35 P.M. - 6:20 P.M. 8,200
-
9:18 A.M. - 12:00 P.M. 40,800
_
49
-------
TABLE 7 (Continued)
1970 COMBINED SEWAGE DISCHARGES - VOLUME AND DURATION
PRECIPITATION
DATE (inches)
JUNE 17
JUNE 19
JUNE 25
JUNE 30
JULY 2
JULY 3
JULY 4
JULY 7
JULY 13
JULY 14
JULY 15
JULY 18
JULY 27
JULY 28
.07
.04
1.02
.05
.25
0.05
.16
.36
.60
.47
.13
.61
.07
.80
DURATION
OF DISCHARGE
OF POND
7:20 A.M.
8:15 P.M.
1:10 A.M.
2:13 A.M.
8:38 P.M.
2:33 A.M.
4:35 A.M.
4:10 A.M.
5:45 A.M.
8:50 A.M.
3:00 A.M.
11:57 P.M.
2:00 P.M.
10:20 P.M.
- 7:37 A.M.
-
- 1:25 A.M.
-
- 1:22 A.M.
- 2:33 A.M.
-
-
- 12:17 A.M.
- 3:25 A.M.
- 7:50 A.M.
- 4:37 A.M.
- 6:43 A.M.
- 9:23 A.M.
_ 3:23 A.M.
- 2:05 A.M.
-
- 3:20 P.M.
- 12:30 A.M.
VOLUME OF
DISCHARGE
TO POND
(cu. ft.)
2,900
-
148,300
-
900
800
-
-
61,100
15,700
51,400
800
20,900
6,700
10,000
62,700
-
106,500
52,600
JULY 30
.90
.2:28 A.M. - 3:27 A.M.
152,300
50
-------
TABLE 7 (Continued)
1970 COMBINED SEWAGE DISCHARGES - VOLUME AND DURATION
PRECIPITATION
DATE (inches)
JULY
AUG.
AUG.
AUG.
AUG.
SEPT.
SEPT.
SEPT.
SEPT.
SEPT.
SEPT.
SEPT.
SEPT.
SEPT.
SEPT.
SEPT.
31
11
15
18
29
2
3
6
9
14
15
17
21
23
24
25
.09
2.63
.18
.02
.24
.12
.25
.09
1.41
.70
.96
-
.21
.02
1.28
.21
.46
.26
VOLUME OF
DURATION DISCHARGE
OF DISCHARGE TO POND
OF POND (cu. ft.)
2:13 P.M. - 2:28 P.M. 1,300
2:47 P.M. - 5:10 P.M. 527,300
-
-
4:20 A.M. - 10:45 A.M. 82,700
2:50 A.M. - 3:25 A.M. 3,500
11:25 P.M. - 12:10 A.M. 12,000
-
4:40 A.M. - 11:05 A.M. 288,400
3:35 P.M. - 8:30 P.M. 72,500
7:30 P.M. - 9:40 P.M. 24,500
6:00 A.M. - 8:40 A.M. 68,000
-
5:10 A.M. - 9:45 A.M. 188,300
10:15 P.M. - 10:45 P.M. 1,000
2:45 A.M. - 9:55 A.M. 70,300
-
51
-------
TABLE 7 (Continued)
1970 COMBINED SEWAGE DISCHARGES - VOLUME AND DURATION
PRECIPITATION
DATE (inches)
OCT.
OCT.
OCT.
OCT.
OCT.
OCT.
OCT.
OCT .
OCT.
OCT.
OCT.
OCT.
OCT.
OCT.
7
8
9
11
22
23
24
25
26
27
28
29
30
31
.64
1.10
.38
.04
.01
.45
.35
.09
1.17
.42
.13
.15
.06
.17
VOLUME OF
DURATION DISCHARGE
OF DISCHARGE TO POND
OF POND (cu. ft.)
2:30 P.M. - 6:20 P.M. 179,900
5:00 A.M. - 9:45 A.M. 138,300
11:05 A.M. - 11:20 A.M. 1,200
12:50 P.M. - 1:50 P.M. 41,500
-
-
6:55 P.M. - 12:00 A.M. 43,400
12:00 A.M. - 5:30 A.M. 33,850
-
1:15 A.M. - 2:30 A.M. 10,600
3:05 P.M. - 7:10 P.M. 41,700
8:00 P.M. - 12:00 A.M. 91,600
12:00 A.M. - 9:20 A.M. RECORDER
OUT OF
ORDER
- -
_
52
-------
TABLE 7 (Continued)
1970 COMBINED SEWAGE DISCHARGES - VOLUME AND DURATION
DURATION
PRECIPITATION OF DISCHARGE
DATE (inches) TO POND
NOV.
NOV.
NOV.
NOV.
« NOV.
NOV.
NOV.
NOV.
NOV.
NOV.
NOV.
1
2
3
7
9
11
18
19
20
25
26
.13
.16
.64 12:20 A.M. - 4:50 A.M.
.03
.79 2:30 A.M. - 8:25 A.M.
9:55 A.M. - 10:45 A.M.
.06
.06
.32 10:15 P.M. - 12:00 A.M.
.15 12:00 A.M. - 12:45 A.M.
.01
.42 (SNOW)
VOLUME OF
DISCHARGE
TO POND
(cu. ft.)
-
-
116,700
-
73,700
4,500
-
-
6,500
1,200
-
-
DEC. 1
.02
3:00 A.M. - 7:45 A.M.
6,400
53
-------
TABLE 8
BOD5 AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1969
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
CONSTITUENT (mg/L)
5
10
15
20
25
30
35
40
ELAPSED 45
TIME FROM 50
START OF 55
OVERFLOW 60
TO 65
SAMPLING 70
(MINUTES) 75
80
85
90
95
100
105
110
115
120
AVG.
LOAD (LB.)
APRIL
20
8:35 AM
10:30 AM
BOD5
113
135
196
116
140
2.10
SS
320
276
267
300
291
440
27
12:42 AM
2:07 AM
BOD5
227
212
208
252
223
224
330
SS
464
484
640
692
360
528
770
MAY
1
6:25 AM
7:25 AM
BOD5
191
112
165
113
102
102
132
122
122
129
116
125
113
146
111
108
106
106
108
119
122
90
SS
400
240
248
80
100
56
164
132
156
212
150
160
120
132
134
188
228
200
224
232
211
150
1
12:58 PM
1:38 PM
BOD5
91
223
250
278
210
60
SS
244
414
472
400
382
110
54
-------
TABLE 8 (Continued)
BOD5 AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1969
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
' CONSTITUENT img/L)
' 5
10
15
20
25
30
35
: 40
ELAPSED 45
• TIME FROM 50
'START OF 55
OVERFLOW 60
TO ; 65
'SAMPLING 70
, (MINUTES) 75
! 80
85
i 90
95
100
105
; no
115
120
AVG.
LOAD (LB.)
JUNE
11
4:00 AM
6:50 AM
BODC
179
177
137
195
183
122
117
112
137
155
148
151
-
SS
80
134
202
240
216
146
220
228
322
146
186
256
198
-
22
4:30 PM
6:40 PM
BODs
74
72
135
212
247
169
206
167
44
147
-
SS
722
450
240
472
326
198
268
162
70
323
-
25
10:30 AM
1:50 PM
BOD5
218
229
175
167
213
172
166
177
186
182
209
168
207
134
146
157
182
-
SS
374
604
284
106
286
252
172
172
260
242
228
238
282
192
240
218
259
-
55
-------
TABLE 8 (Continued)
BOD5 AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1969
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
CONSTITUENT (mg/L
5
10
15
20
25
30
35
40
ELAPSED 45
TIME FROM 50
START OF 55
OVERFLOW 60
TO 65
SAMPLING 70
(MINUTES) 75
80
85
90
95
100
105
110
115
120
AVG.
LOAD (LB.)
JULY
2
5:22 AM
7:17 AM
BODs
96
73
23
21
97
59
42
35
42
58
46
23
77
68
32
70
93
67
75
37
90
60
24
20
55
530
SS
140
114
54
20
144
46
38
40
22
28
14
28
88
66
52
88
94
22
94
20
90
58
38
46
60
580
8
9:00 AM
11:35 AM
BODs
162
198
199
192
217
106
91
65
62
59
73
55
65
104
129
174
177
125
1480
SS
222
458
446
386
448
318
306
154
226
178
118
100
114
130
152
198
210
245
2900
14
5:38 AM
9:22 AM
BODs
129
99
154
137
112
108
86
56
64
66
54
43
37
52
21
69
52
58
75
81
112
44
78
2420
SS
762
200
372
418
318
282
252
226
142
246
222
206
160
228
164
322
180
148
168
186
176
186
253
7830
26
11:33 PM
9:40 AM
BODs
174
184
230
229
211
151
138
187
187
141
197
178
126
227
175
123
150
165
150
125
138
164
164
170
690
SS
436
500
820
850
500
90
500
200
230
268
368
248
232
312
224
268
160
148
156
112
140
100
320
310
1260
56
-------
TABLE 8 (Continued)
BOD5 AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1969
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
CONSTITUENT (mg/L)
5
10
15
20
25
30
35
40
ELAPSED 45
TIME FROM 50
START OF 55
OVERFLOW 60
TO 65
SAMPLING 70
(MINUTES) 75
80
85
90
95
100
105
110
115
120
AVG.
LOAD (LB.)
AUGUST
6
9:55 PM
12:45 AM
BOD^
140
169
260
156
59
59
47
41
97
38
41
114
57
43
44
134
138
96
111
129
142
144
103
2760
SS
232
328
396
276
204
184
284
304
364
236
164
332
252
216
220
272
348
252
252
330
180
292
269
7210
SEPTEMBER
4
3:42 PM
4:40 PM
BODs
323
407
500+
488
438
396
500+
368
246
296
317
317
383+
310+
SS
269
308
920
1044
392
496
500
412
312
294
384
292
471
380
22
5:05 PM
8:00 PM
BODs
281
483
486
341
465
261
188
233
271
215
322
236
315
730
SS
332
580
768
572
852
332
480
404
464
280
656
240
497
1160
29
1:05 AM
3:10 AM
BOD5
135
165
149
315
163
125
147
164
179
144
155
121
154
117
105
113
147
140
184
99
141
103
148
130
SS
224
256
340
848
188
192
256
160
244
220
260
284
408
176
152
148
320
300
288
176
344
152
270
230
57
-------
TABLE 8 (Continued)
BOD5 AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1969
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
CONSTITUENT (mg/L)
5
10
15
20
25
30
35
40
ELAPSED 45
TIME FROM 50
START OF 55
OVERFLOW 60
TO 65
SAMPLING 70
(MINUTES) 75
80
85
90
95
100
105
110
115
120
AVG.
LOAD (LB.)
OCTOBER
12 30
9:17 PM
1:35 AM
BOD5
230
136
189
165
173
153
179
190
196
169
178
360
SS
316
164
220
224
308
184
248
308
296
232
250
510
8:10 PM
10:15 PM
BOD5
156
92
82
66
77
83
62
84
71
108
88
430
SS
228
118
72
62
96
100
54
94
80
112
102
50
58
-------
TABLE 9
BOD5 AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1970
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
CONSTITUENT (mg/L)
5
10
15
20
25
30
35
40
ELAPSED 45
TIME FROM 50
START OF 55
OVERFLOW 60
TO 65
SAMPLING 70
(MINUTES) 75
80
85
90
95
100
105
110
115
120
AVG.
LOAD (LB.)
APRIL
22
5:45 PM
6:30 PM
BOD5
80
85
86
171
89
84
187
67
77
91
121
96
56
68
56
45
68
90
30
SS
432
360
340
240
124
152
280
124
112
132
176
152
128
132
120
136
112
191
70
MAY
9
9:25 AM
10:55 AM
BODS
196
219
190
163
150
138
132
117
134
129
138
155
160
147
151
184
141
143
149
159
164
165
157
SS
532
472
496
360
324
276
244
176
248
224
248
288
264
248
252
264
248
256
200
204
244
232
220
283
1520
12
1:20 AM
2:05 AM
BODS
66
51
77
53
39
49
52
56
65
44
54
68
51
62
55
52
57
41
42
43
55
38
38
38
52
80
SS
192
140
132
144
124
148
172
200
132
108
124
184
152
112
148
136
144
100
128
108
120
124
120
80
136
200
28
12:00 AM
3:55 AM
BOD^
91
78
101
146
94
93
90
87
88
86
99
113
107
98
670
SS
124
124
100
260
228
164
80
44
84
88
108
144
156
131
890
59
-------
TABLE 9 (Continued)
BOD5 AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1970
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
CONSTITUENT (mg/L)
5
10
15
20
25
30
35
40
ELAPSED 45
TIME FROM 50
START OF 55
OVERFLOW 60
TO 65
SAMPLING 70
(MINUTES) 75
80
85
90
95
100
105
110
115
120
AVG.
LOAD (LB.)
JUNE
12
5:35 PM
6:20 PM
BOD5
92
133
143
205
232
233
173
90
SS
452
348
264
632
636
392
454
230
15
9:18 AM
12:00 PM j
BOD5
128
267
132
237
98
77
121
105
129
251
170
151
202
141
180
139
177
172
211
150
162
410
SS
136
616
176
440
324
212
272
248
276
448
176
264
416
144
176
204
312
248
240
236
278
700
25
.8:15 PM
1:25 AM.
BOD5
226
219
192
212
1950
SS
322
268
188
259
2380
60
-------
TABLE 9 (Continued)
BOD. AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1970
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
CONSTITUENT (mg/L)
5
10
15
20
25
30
35
40
ELAPSED 45
TIME FROM 50
START OF 55
OVERFLOW 60
TO 65
SAMPLING 70
(MINUTES) 75
80
85
90
95
100
105
110
115
120
AVG.
LOAD (LB.)
JULY
7
8:38 PM
12:17 AM
BOD5
453
343
311
432
368
429
459
248
164
384
365
425
320
313
403
230
298
213
316
181
252
174
132
314
1190
SS
596
656
372
688
624
628
984
616
576
580
568
880
400
752
640
316
388
256
352
220
516
460
212
530
2020
13
4:35 AM
7:50 AM
BOD^
374
362
352
312
337
357
372
418
413
475
443
342
227
208
281
249
237
182
330
1050
SS
192
284
324
208
192
232
256
236
244
432
688
216
488
580
520
468
304
272
341
1090
14
8:50 AM
9:23 AM
BOD5
41
95
37
73
148
123
119
97
92
120
SS
132
260
100
156
284
164
200
136
179
230
18
11:57 PM
2:05 AM
BODS SS
161 458
174 342
75 136
91 282
96 156
84 216
141
77 222
91 230
74 182
71 190
77 170
97 150
89 168
76 116
81 178
91 108
49 76
65 94
82 326
70 310
99 250
91 208
350 810
61
-------
TABLE 9 (Continued)
BOD5 AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1970
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
CONSTITUENT (mg/L)
5
10
15
20
25
30
35
40
ELAPSED 45
TIME FROM 50
START OF 55
OVERFLOW 60
TO 65
SAMPLING 70
(MINUTES) 75
80
85
90
95
100
105
110
115
120
AVG.
LOAD (LB.)
JULY
28
10:20 PM
12:30 AM
BOD5
366
222
278
267
157
93
100
198
172
311
278
227
227
387
209
210
244
208
192
229
750
SS
440
568
360
360
612
576
588
756
640
596
472
600
512
320
296
316
300
340
481
1570
30
2:28 AM
3:27 AM
BOD5
99
81
102
257
214
96
78
148
96
114
216
156
100
101
93
83
118
111
252
136
178
135
1270
SS
140
132
196
448
340
428
368
392
352
360
336
604
292
216
204
168
148
220
168
416
260
228
292
2760
AUGUST
11
2:47 PM
5:10 PM
BOD5 SS
66
59
83
73
58
38
47
33
33
32
27
33
41
22
31
32
30
48
39
37
30
47
43
1410
328
208
208
532
520
680
716
664
380
360
248
268
248
196
336
360
296
380
228
272
148
224
355
11610
29
4:20 AM
10:35 AM
BOD5
119
110
141
113
138
112
208
86
128
87
81
104
88
71
91
105
75
109
560
SS
452
560
428
400
608
352
544
316
420
224
260
268
304
256
380
444
276
382
1960
62
-------
TABLE 9 (Continued)
BOD5 AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1970
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
CONSTITUENT (mg/L)
5
10
15
20
25
30
35
40
ELAPSED 45
TIME FROM 50
START OF 55
OVERFLOW 60
TO 65
SAMPLING 70
(MINUTES) 75
80
85
90
95
100
105
110
115
120
AVG.
LOAD (LB.)
SEPTEMBER
2
2:50 AM
3:2f
BOD5
101
78
115
129
89
96
93
83
85
145
88
134
86
102
20
) AM
SS
268
140
304
272
100
136
124
164
208
352
224
324
156
213
50
6
4:40 AM
11:05 AM
BOD5
136
183
61
134
101
95
174
58
63
88
37
24
71
51
142
84
69
90
115
72
92
1650
SS
356
348
224
192
176
196
356
188
244
248
104
92
140
108
324
292
152
332
300
424
240
4290
9
3:35 PM
8:30 PM
BOD5
424
202
178
146
163
158
140
184
112
147
292
229
193
319
323
211
185
286
197
163
213
960
SS
628
292
292
164
312
256
216
200
152
404
692
448
220
656
812
496
264
484
332
300
381
1710
15
6:00 AM
8:40 AM
BOD5
125
264
108
323
103
80
69
67
186
101
103
229
121
170
77
124
112
139
590
SS
220
648
200
712
224
156
188
152
424
244
224
360
256
372
84
244
172
287
1210
63
-------
TABLE 9 (Continued)
BOD5 AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1970
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
CONSTITUENT (mg/L)
5
10
15
20
25
30
35
40
ELAPSED 45
TIME FROM 50
START OF 55
OVERFLOW 60
TO 65
SAMPLING 70
(MINUTES) 75
80
85
90
95
100
105
110
115
120
AVG.
LOAD (LB.)
SEPTEMBER
21
5:10 AM
9:45 AM
BOD5
95
101
141
66
96
128
158
145
105
185
201
318
301
196
176
161
1880
SS
712
564
512
424
412
424
432
368
276
344
612
488
564
388
288
454
5300
24
2:45 AM
9:55 AM
BOD5
153
143
138
154
165
193
170
183
181
157
84
53
60
81
108
115
113
112
93
88
107
91
89
123
540
SS
280
284
172
148
216
236
256
180
204
144
120
56
124
112
180
132
120
116
132
112
152
112
136
162
710
OCTOBER
7
2:30 PM
6:20 PM
BOD^
254
348
416
312
286
179
185
147
177
192
138
139
248
137
223
149
119
165
207
219
204
212
2360
SS
288
512
424
320
252
264
348
288
312
268
184
116
296
204
192
216
152
380
348
292
348
286
3190
24
12:00 AM
5:30 AM
BOD5
237
192
108
169
307
136
226
157
145
132
142
274
280
284
239
202
420
SS
264
280
116
256
532
180
312
252
268
256
248
288
224
452
360
286
600
64
-------
TABLE 9 (Continued)
BOD5 AND SUSPENDED SOLIDS FOR
COMBINED SEWAGE DISCHARGES TO POND
1970
MONTH
DATE
BEGIN OVERFLOW
END OVERFLOW
CONSTITUENT (mg/L)
5
10
15
20
25
30
35
40
ELAPSED 45
TIME FROM 50
START OF 55
OVERFLOW 60
TO 65
SAMPLING 70
(MINUTES) 75
80
85
90
95
100
105
110
115
120
AVG.
LOAD (LB.)
NOVEMBER
3
12:20 AM
4:50 AM
BOD5
56
45
55
57
54
59
133
54
49
60
68
46
53
32
39
39
30
37
33
28
51
370
ss
172
104
104
132
60
144
148
100
80
112
112
116
132
132
152
180
192
168
164
160
133
960
9
9:55 AM
10:45 AM
BOD5
77
78
66
64
56
49
86
81
53
55
85
38
66
300
SS
156
88
84
100
144
152
180
140
120
100
176
100
128
580
19
10:15 PM
12:00 AM
BOD5
56
44
42
72
36
33
28
55
58
33
42
42
23
42
46
64
68
46
20
SS
132
96
92
136
100
100
52
104
112
72
80
64
72
88
88
108
148
97
40
DECEMBER
1
3:00 AM
7:45 AM
BOD5
102
126
115
92
116
133
86
84
121
97
109
110
158
72
69
61
69
60
66
59
64
94
40
SS
248
288
320
256
228
324
212
236
312
232
244
264
260
184
192
216
188
196
204
204
156
236
90
65
-------
TABLE 10
AVERAGE CHARACTERISTICS - 1969 DISCHARGES TO POND
DATE
APRIL
APRIL
MAY
MAY
JUNE
JUNE
JUNE
JULY
JULY
JULY
JULY
AUG.
SEPT.
SEPT.
20
27
1
1
11
22
25
2
8
14
26
6
4
22
VOLATILE
. SETTLEABLE SUSPENDED
SOLIDS SOLIDS
(mg/L) (mg/L)
174
302
105
192
113
172
154
39
151
115
230
160
403 355
177 382
FECAL
COLIFORM (xlO6)
(MPN/100 ml)
1.07
-
-
1.63
9.23
3.73
6.04
-
4.44
13.13
45.87
-
40.50
61.20
TOTAL
COLIFORM (xlO6)
(MPN/100 ml)
12.05
-
-
91.75
73.00
35.78
84.60
-
134.06
112.55
186.13
-
254.00
382.00
66
-------
TABLE 10 (Continued)
AVERAGE CHARACTERISTICS - 1969 DISCHARGES TO POND
DATE
SETTLEABLE
SOLIDS
(mg/L)
VOLATILE
SUSPENDED
SOLIDS
(mg/L)
FECAL
COLIFORM (xlO6)
(MPN/100 ml)
TOTAL
COLIFORM (xlO6)
(MPN/100 ml)
SEPT. 29
288
226
10.02
65.20
OCT. 12
OCT. 30
137
33
213
36
10.65
144.80
67
-------
TABLE 11
AVERAGE CHARACTERISTICS - 1970 DISCHARGES TO POND
DATE
APRIL 22
MAY 9
MAY 12
MAY 28
JUNE 12
JUNE 15
JUNE 25
JULY 7
JULY 13
JULY 14
JULY 18
JULY 28
JULY 30
AUGUST 11
AUGUST 29
SEPT. 2
SETTLEABLE
SOLIDS
(mg/L)
146
218
124
112
320
228
259
270
211
108
208
437
235
338
366
171
VOLATILE
SUSPENDED
SOLIDS
(mg/L)
106
177
90
90
387
211
253
433
279
143
173
315
187
150
281
177
FECAL
COLIFORM (xlO )
(MPN/100 ml)
0.28
.30
.14
.26
1.47
1.39
2.57
9.29
7.06
7.00
-
6.06
-
3.00
1.26
.88
TOTAL
COLIFORM (xlO6)
(MPN/100 ml)
12.06
45.87
39.09
18.00
107.33
51.06
59.67
160.74
347.22
173.75
\
202.63
-
113.64
80.05
121.38
68
-------
TABLE 11 (Continued)
AVERAGE CHARACTERISTICS - 1970 DISCHARGES TO POND
DATE
SEPT.
SEPT.
SEPT.
SEPT.
SEPT.
OCT.
OCT.
NOV.
NOV.
NOV.
6
9
15
21
24
7
24
3
9
19
SETTLEABLE
SOLIDS
(mg/L)
236
294
216
391
166
270
268
136
118
87
VOLATILE
SUSPENDED
SOLIDS
(mg/L)
175
310
251
246
111
213
235
114
119
80
FECAL
COLIFORM (x!06)
(MPN/100 ml)
.34
4.14
1.21
.69
.70
1.81
1.06
.14
.26
.12
TOTAL
COLIFORM (xlO6)
(MPN/100 ml)
31.75
207.75
91.18
86.00
65.55
76.67
59.67
15.84
12.33
6.06
DEC.
227
149
4.94
AVERAGE
(1969-1970) 225
196
7.19
101.79
69
-------
TABLE 12
CHARACTERISTICS OF POND OVERFLOWS TO RIVER
DATE
JULY 14, 1969
AUG. 6, 1969
\UG. 11, 1970
PRECIP-
ITATION
(inches)
2.53
1.97
2.63
DURATION
OF
OVERFLOW
6:55 AM-
9:15 PM
12:00 PM-
1:00 AM
3:30 PM-
5:10 PM
VOL. OF
OVERFLOW
(cu.ft.)
82,300
55,000*
203,600
TIME OF
SAMPLING
7:00 AM
8:00 AM
9:00 AM
AVG.CONC.
LOAD
12:00 PM
1:00 AM
AVG.CONC.
LOAD
3:30 PM
4:30 PM
AVG.CONC.
LOAD
BOD5
(mg/L)
53
73
58
61
310 LB.
26
28
27
90 LB.
50
27
38
480 LB.
SUSPENDED
SOLIDS
(mg/L)
246
238
140
- 208
1070 LB.
76
88
82
280 LB.
184
204
194
2460 LB.
SETTLEABLE
SOLIDS
(mg/L)
30
25
20
_
-
174
COLIFORMS (MPN/100 ml)
FECAL TOTAL
18.8 x 106
19.7 x 106
21.4 x 106
_
-
5 x 106
1 x 106
134 x 106
137 x 106
135 x 106
_
-
120 x 106
310 x 106
* ESTIMATED FROM DISCHARGE TO POND.
-------
TABLE 13
1970 POND DRAIN DATA
DATE
MAY
MAY
JUNE
JUNE
JUNE
JULY
JULY
JULY
JULY
JULY
AUGUST
SEPT.
SEPT.
SEPT.
OCT.
OCT.
SETTLEABLE
SOLIDS
(mg/L)
28
30
12
15
25
7
13
14
15
28
29
2
6
15
7
24
4710
-
502
-
190
-
128
97
98
274
112
-
606
1150
166
226
SUSPENDED
SOLIDS
(mg/L)
4910
316
532
-
208
326
136
124
136
308
116
116
620
1160
172
228
FECAL
COLIFORM
(MPN/lOOml)
20
660
460
900
400
4.6
6
,000
,000
,000
,000
,000
x 106
x 106
106
400
240
180
400
1.2
520
-
,000
,000
,000
,000
x 106
,000
TOTAL
COLIFORM
(MPN/lOOml)
2.8
37
22
26
16
162
130
;30
120
10
21
12
140
74
31
x
x
X
X
X
X
X
X
X
X
X
X
X
X
X
106
106
106
106
106
106
106
106
106
106
106
106
106
106
106
BOD5
(mg/L
433
59
81
-
58
36
103
37
37
80
17
44
-
185
74
53
71
-------
TABLE 14
WASTEWATER TREATMENT PLANT DATA
1969
N5
DATE
PRECIP-
ITATION
INFLUENT INFLUENT
FLOW BODC
(inches) (mgd)
April 2
5
8
11
14
17
20
23
26
27
29
May 1
2
5
6
10
11
17
19
20
21
23
26
29
31
0.07
.14
.20
.13
.48
.05
.17
.02
.66
.22
.12
.10
.21
1.74
1.49
2.79
4.13
1.71
2.15
1.97
2.00
1.98
1.64
2.95
2.14
3.39
1.71
2.63
2.18
1.41
3.13
1.20
2.01
1.80
1.79
1.08
1.90
1.33
(mg/L)
478
367
177
193
398
462
375
260
395
204
369
315
364
366
343
tlb)
6940
4560
3990
6650
7140
7590
6260
4340
9720
5770
9630
5280
5430
3300
5440
EFFLUENT
(mg/L)
10
8
53
16
69
22
18
32
89
52
15
12
25
30
20
^lb)
150
100
1230
550
1270
350
300
530
2190
1470
390
200
370
270
320
BOD
REMOVAL
7=
98.0
97.8
70.1
91.6
82.6
95.3
95.2
87.7
77 .4
74.6
95.9
96.2
93.1
91.8
94.2
INFLUENT
SUSPENDED
SOLIDS
(mg/L)
976
372
308
288
540
1188
672
252
628
540
816
636
936
876
1124
EFFLUENT
SUSPENDED SS
SOLIDS REMOVAL
(lb) (mg/L)
14,160
4,620
7,170
9,920
9,680
19,520
11,210
4,160
15,450
15,270
9,600
10,660
13,970
7,890
17,810
14
22
60
3
68
28
34
22
94
150
61
27
41
42
61
(lb)
200
270
1400
100
1220
460
570
360
2310
4240
720
450
610
380
970
7>
98.5
94.2
80.5
98.9
87.7
97.7
94.8
91.2
84.8
72.3
92.5
95.7
95.6
95.4
94.6
-------
TABLE 14 (continued)
WASTEWATER TREATMENT PLANT DATA
1969
DATE
June 1
4
7
10
11
12
13
16
19
22
25
26
July 1
2
4
7
8
10
13
14
17
21
24
26
27
30
PRECIP-
ITATION
(inches)
.88
.53
.48
.68
.62
.69
.15
1.01
2.53
.03
.24
.23
INFLUENT INFLUENT
FLOW BODR
(mgd)
1.80
1.94
2.00
2.25
2.94
4.25
2.94
1.76
2.27
2.09
2.43
3.28
2.59
2.40
2.56
1.92
2.42
2.24
2.19
2.40
2.89
2.24
2.88
2.63
3.61
3.57
(mg/L)
168
233
229
347
240
229
387
99
196
213
294
243
178
235
243
272
209
274
(lb)
2520
3770
3820
6510
6000
3360
7330
1730
3970
4600
4710
4540
3250
5660
4540
6530
6290
8160
EFFLUENT
BODq
(mg/L)
10
27
6
22
23
18
39
32
8
13
26
24
4
40
15
14
6
21
(lb)
150
440
100
410
580
260
740
560
160
280
420
450
70
960
280
340
180
630
BOD
REMOVAL
%
94.0
88.4
97.4
93.7
90.4
92.1
89.8
67.8
95.8
93.9
91.2
90.2
94.8
83.0
93.8
94.9
97.1
92.3
INFLUENT
SUSPENDED
SOLIDS
(ine/L)
536
492
1564
940
564
576
808
248
332
924
912
556
268
660
520
556
704
(lb)
8,050
7,960
26,090
17,640
13,830
8,450
15,300
4,320
6,730
19,960
14,600
10,390
4,890
15,910
9,710
13,350
20,960
EFFLUENT
SUSPENDED
SOLIDS
SS
REMOVAL
(mg/L) (lb) %
15
44
25
24
33
40
41
58
27
26
38
28
8
34
29
27
37
230
710
420
450
810
590
780
1010
550
560
610
520
150
820
700
650
1100
97.2
91.2
98.3
97.6
94.2
93.1
94.8
76.6
91.8
97.2
95.8
94.9
97.1
94.8
94.2
95.1
94.8
-------
TABLE 14 (continued)
WASTEWATER TREATMENT PLANT DATA
1969
PREC IP-
DATE ITATION
(inches)
August 2
5
6 2.37
8
11
14
17
20
23
29 .14
Sept. 1
4 .18
7
10
13
16
19
22 .36
24
25 .22
28
29 .15
INFLUENT INFLUENT
FLOW BODr;
> (mgd)
3.07
2.36
2.02
3.86
1.62
4.58
3.45
3.65
2.76
2.27
1.69
2.53
2.12
2.23
2.44
2.50
2.18
1.68
2.24
2.57
1.62
2.35
(mg/L) "(lb)
112
138
176
188
124
230
353
158
250
265
262
262
262
267
271
314
311
353
174
2870
2720
5670
2540
4740
6620
10750
3640
4730
3740
5530
4630
4870
5430
5650
5710
4360
6600
2350
EFFLUENT
(mg/L)
6
25
21
12
15
10
36
32
36
20
26
10
32
12
15
18
17
11
32
(lb)
150
490
680
160
570
290
1100
740
680
280
550
180
600
240
310
330
240
210
430
BOD
REMOVAL
7,
94.6
81.9
88.1
93.6
87.9
95.7
89.8
79.8
85.7
92.4
90.2
96.2
87.7
95.5
94.4
94.4
94.4
96.8
81.7
INFLUENT
SUSPENDED
SOLIDS
(mg/L)
700
420
488
548
932
1180
1376
832
1104
536
520
760
1164
1304
808
832
1164
752
(lb)
17,920
8,270
6,590
20,930
26,820
35,920
31,670
15,750
15,560
11,310
9,190
14,100
23,700
27,200
18,900
11,660
21,750
10,160
EFFLUENT
SUSPENDED SS
SOLIDS REMOVAL
(mg/L) (lb) 7,
23
28
39
28
36
43
47
35
35
21
18
19
18
12
16
30
19
21
580
550
530
1070
1040
1310
1080
660
490
440
320
350
370
250
290
420
350
280
96.7
93.4
92.0
94.9
96.1
96.4
96.5
95.8
96.8
96.1
96.6
97.5
98.3
98.9
97.9
96.4
98.3
97.2
-------
TABLE 14 (continued)
WASTEWATER TREATMENT PLANT DATA
1969
PREC IP-
DATE ITATION
Oct. 1
4
5
7
10
12
13
15
16
19
22
25
28
30
31
Nov." 1
3
6
9
12
15
17
18
24
28
(inches)
.52
.20
.78
.46
.02
.10
.46
.28
.08
.48
INFLUENT INFLUENT
FLOW BOD,;
(mgd)
2.08
2.17
1.72
2.60
2.47
1.88
2.51
2.47
3.63
1.76
2.08
2.02
2.11
1.98
2.94
2.97
1.75
2.25
1.99
2.30
1.99
1.61
3.18
1.77
1.63
(mg/L)
267
189
357
404
346
199
127
549
182
213
244
-
297
337
270
220
141
330
330
197
(lb)
4630
3150
7740
8330
7240
6030
1800
9530
3060
3750
5980
4460
6320
4480
4220
2340
8750
4870
2680
EFFLUENT
(mg/L)
11
9
21
20
77
27
14
21
43
23
47
17 -
17
21
30
12
24
21
19
"Ub)
190
150
460
410
160
820
200
360
730
400
1150
260
320
350
580
200
640
310
260
BOD
REMOVAL
%
95.8
95.3
94.1
95.0
77.8
86.4
89.0
96.2
76.4
89.2
80.7
94.3
94.8
92.2
86.4
91.6
92.7
93.6
90.3
INFLUENT
SUSPENDED
SOLIDS
(mg/L)
720
1124
1036
912
948
892
484
1264
612
740
1001
1216
936
920
276
328
752
1048
876
(lb)
12,490
20,340
22,460
18,790
19,840
27,000"
7,100
21,930
10,310
13,020
24,540
17,750
17,560
15,270
5,290
5,440
19,940
15,470
11,910
EFFLUENT
SUSPENDED
SOLIDS
(mg/L) (lb)
24
14
35
27
54
42
16
29
39
50
60
22
28
44
44
23
30
45
52
420
250
760
560
1130
1270
230
500
660
880
1470
320
530
730
840
380
800
660
710
SS
REMOVAL
°L
96.8
98.9
96.7
97.2
94.3
95.2
96.8
97.7
93.7
93.3
93.2
98.2
97.1
95.3
84.1
93.0
96.1
95.7
93.9
-------
TABLE 15
WASTEWATER TREATMENT PLANT DATA
1970
DATE
April 5
6
9
12
15
18
19
20
21
22
23
24
27
28
30
May 1
3
6
9
12
13
14
15
18
19
PRECIP-
ITATION
(inches )
0.14
.08
.12
.77
.10
.17
.04
.06
.06
.08
.56
.27
.41
.52
.03
INFLUENT INFLUENT
FLOW BODq
i (mgd)
1.90
2.15
3.54
1.88
2.34
2.28
1.87
3.15
3.34
2.85
2.38
1.92
1.55
2.05
1.91
1.94
1.63
1.91
1.80
2.52
1.89
2.70
3.12
1.73
2.38
(mg/L) "Ub)
500
480
212
231
245
218
462
229
230
205
244
257
281
392
319
8970
14170
3320
4510
4660
6070
7400
2960
3660
2790
3890
3860
5910
10200
4600
EFFLUENT
(mg/L)
26
22
18
16
20
31
25
25
24
12
48
20
22
22
30
Tib)
470
650
280
310
380
860
400
320
380
160
760
300
460
570
430
BOD
REMOVAL
%
94.8
95.4
91.5
93.1
91.8
85.7
94.5
89.0
90.0
94.1
80.3
92.2
92.1
94.3
90.5
INFLUENT
SUSPENDED
SOLIDS
(mg/L)
1728
1780
752
824
624
760
1940
612
616
240
344
684
902
960
1000
(lb)
30,980
52,550
11,790
16,080
11,870
21,170
31,060
7,910
9,810
3,260
5,480
10,270
18,960
24,980
14,430
EFFLUENT
SUSPENDED SS
SOLIDS REMOVAL
(mg/L) (lb) %
23
21
24
25
33
47
57
37
30
6
31
47
21
22
30
410
620
380
490
630
1310
910
480
480
80
490
710
840
570
430
98.7
98.8
96.8
96.9
94.7
93.8
97.0
93.9
95.1
97.5
91.0
93.1
97.6
97.7
97.0
-------
TABLE 15 (continued)
WASTEWATER TREATMENT PLANT .DATA
1970
DATE
May 21
22
23
24
25
27
28
29
30
31
June 2
5
8
9
11
12
13
14
15
16
17
19
20
23
25
26
29
30
PRECIP-
ITATION
(inches)
.47
.50
.06
.08
.10
.72
.48
.04
.26
.42
.06
.22
.17
.08
.68
.02
.07-
.04
1.02
.05
INFLUENT INFLUENT
FLOW BODq
(mgd)
2.25
3.45
3.64
2.41
2.18
1.97
3.64
1.48
2.22
1.87
2.51
2.01
1.90
2.45
2.80
2.52
2.32
1.81
2.19
3.43
2.29
2.30
1.86
2.21
1.84
4.79
1.82
2.28
(mg/L)
257
155
313
133
322
363
289
509
377
142
190
220
275
(lb)
4820
3120
5800
2780
5400
5760
6750
7680
7200
2200
3530
8790
4170
EFFLUENT
(mg/L)
25
30
27
40
22
39
26
29
28
26
12
9
25
(lb)
470
600
500
720
370
620
610
440
530
404
220
360
380
BOD
REMOVAL
%
90.5
83.5
91.0
70.0
93.3
89.4
91.0
94.3
92.0
81.7
93.2
95.9
90.9
INFLUENT
SUSPENDED
SOLIDS
(mg/L)
564
260
784
170
792
1752
560
2028
1344
368
356
912
772
(lb)
10,580
5,230
14,520
3,560
13,280
27,760
13,080
30,610
25,670
5,710
6,560
36,430
11,720
EFFLUENT
SUSPENDED
SOLIDS
SS
REMOVAL
(mg/L) (lb) %
24
14
43
38
30
43
26
20
17
4
23
16
18
440
280
800
800
500
680
610
300
320
60
420
640
270
95.7
94.6
94.5
77.6
96.2
97.5
95.4
99.0
98.8
98.9
93.5
98.2
97.6
-------
00
TABLE 15 (continued)
WASTEWATER TREATMENT PLANT DATA
1970
DATE
PRECIP-
ITATION
INFLUENT INFLUENT
FLOW BOD^
(inches) (mgd)
July 2
3
4
5
7
8
11
12
13
14
15
16
17
18
20
24
27
28
30
31
Aug. 3
6
9
11
12
15
17
.25
.05
.16
.36
.60
.47
.13
.61
.07
.80
.90
.09
2.63
.18
2.24
2.58
4.92
—
2.36
2.45
2.00
1.83
2.42
2.88
3.70
1.98
2.19
1.97
1.67
2.61
1.84
2.04
3.07
3.08
1.83
1.80
1.73
2.24
4.67
2.15
1.70
(mg/L) (lb)
175
191
208
248
318
329
332
561
326
537
266
97
278
386
3270
4250
4140
7640
6010
4620
8610
8350
8200
3990
1400
10830
6920
EFFLUENT
(mg/L)
33
27
28
11
28
31
30
19
16
22
28
8
14
40
(lb)
620
570
180
670
570
420
290
410
340
420
120
550
720
BOD
REMOVAL
7,
81.1
85.8
86.5
95.6
91.3
90.6
91.0
98.3
95.1
96.0
89.4
91.7
94.9
89.6
INFLUENT
SUSPENDED
SOLIDS
(mg/L)
520
312
356
576
688
704
1844
636
1360
540
188
664
764
(lb)
9,710
7,270
9,610
12,570
9,810
28,300
16,280
20,760
8,110
2,710
25,860
13,700
EFFLUENT
SUSPENDED
SOLIDS
SS
REMOVAL
(mg/L) (lb) 7o
31
19
26
15
28
25
29
20
33
35
8
30
14
580
530
250
510
350
450
510
500
530
120
1170
250
94.0
94.0
92.6
97.3
95.9
96.4
98.4
96.8
97.5
93.5
95.7
95.4
98.1
-------
TABLE 15 (continued)
WASTEWATER TREATMENT PLANT DATA
1970
DATE
PRECIP-
ITATION
(inches)
Aug.
Sept.
Oct.
18
21
24
27
29
2
3
5
6
8
9
11
14
15
17
20
21
23
24
25
26
30
3
6
7
8
.02
.24
.37
.09
1.41
.70
.96
.23
.46
.26
.64
1.10
INFLUENT INFLUENT
FLOW BODn;
(mgd)
2.01
1.81
1.79
1.98
2.49
1.92
2.13
1.84
2.06
2.46
4.16
1.79
1.56
2.33
2.12
1.68
1.84
1.96
2.98
2.51
2.68
--
2.09
2.19
2.02
3.18
(mg/L) (lb)
192
236
457
264
196
511
548
256
200
202
123
573
306
544
279
637
•
3220
3560
6820
4360
3140
7840
11240
3820
2600
3570
1720
9370
6840
4860
11630
EFFLUENT
(mg/L)
11
14
64
19
23
7
16
14
23
19
18
13
10
21
7
14
"(lb)
180
210
960
310
370
110
330
210
300
340
250
210
220
120
260
BOD
REMOVAL
7,
94.2
94.0
86.0
92.8
88.3
98.6
97.0
94.5
88.5
90.5
86.1
97.7
96.7
96.1
97.5
97.7
INFLUENT
SUSPENDED
SOLIDS
(mg/L)
376
460
684
620
492
1000
1412
356
440
620
560
676
268
656
416
856
(lb)
6,300
6,940
10,210
10,240
7,880
15,350
28,970
5,310
5,720
10,960
7,850
11,050
5,990
7,250
15,630
EFFLUENT
SUSPENDED
SOLIDS
SS
REMOVAL
(mg/L) (lb) 7,
28
28
40
74
49
12
34
10
46
22
22
21
12
13
15
15
470
420
600
1220
784
180
700
150
600
390
310
340
270
260
270
92.5
93.9
94.1
88.0
90.0
98.8
97.5
97.2
89.5
96.4
96.0
96.8
95.5
98.0
96.3
98.2
-------
oo
o
TABLE 15 (continued)
WASTEWATER TREATMENT PLANT DATA
1970
DATE
Oct. 9
11
12
15
18
22
23
24
25
26
27
28
29
30
31
Nov. 1
2
3
6
7
9
11
12
15
18
19
20
PRECIP-
ITATION
(inches )
.38
.04
.01
.45
.35
.09
1.17
.42
.13
.15
.06
.17
.13
.16
.64
.03
.79
.06
.06
.32
.15
INFLUENT INFLUENT
FLOW BOD,;
i (mgd)
3.89
1.80
1.83
1.83
1.88
2.01
1.99
3.80
1.67
2.47
5.54
2.84
2.57
2.40
2.58
2.07
1.81
3.86
2.17
2.08
2.57
1.83
2.40
1.86
1.96
2.01
3.20
(mg/L) "(lb)
298
125
179
410
265
179
209
148
247
388
255
298
271
1880
9670
6430
8400
8270
4180
2230
4470
8320
5100
4620
4430
EFFLUENT
(mg/L)
6
4
5
14
31
8
3
10
11
14
10
15
12
"(lb)
190
60
80
220
980
370
60
150
200
300
200
230
200
BOD
REMOVAL
%
98.0
93.0
97.2
96.5
88.3
95.5
98.5
93.2
95.5
96.3
96.0
94.9
95.5
INFLUENT
SUSPENDED
SOLIDS
(mg/L)
420
796
516
912
456
408
312
524
1008
744
344
400
(lb)
13,630
12,150
7,880
14,300
21,070
8,170
4,710
9,480
21,610
14,890
5,340
6,540
EFFLUENT
SUSPENDED
SOLIDS
SS
REMOVAL
(mg/L) (lb) %
13
31
16
24
12
12
11
13
17
13
16
6
420
470
240
380
560
240
170
240
360
260
250
100
96.9
96.1
96.8
97.3
97.3
97.0
96.5
97.5
98.3
98.2
95.3
98.5
-------
TABLE 15 (continued)
WASTEWATER TREATMENT PLANT DATA
1970
PRECIP- INFLUENT INFLUENT
DATE ITATION FLOW BOD^
(inches) (mgd)
Nov. 21
24
25
26
27
30
Dec. 1
3
6
9
12
15
18
21
28
30
2.84
2.11
.01 2.21
.42 1.96
1.81
1.84
.02 2.15
1.91
1.76
1.96
2.04
1.98
1.67
1.75
1.56
1.92
(mg/L) (lb)
819
613
363
631
326
480
220
397
669
717
272
474
408
19400
10790
5480
9680
5190
7050
3600
6750
11050
9990
3970
6170
6530
EFFLUENT
(mg/L)
9
8
13
10
6
11
43
13
14
22
6
86
179
tlb)
210
140
200
150
100
160
700
220
230
310
90
1120
2870
BOD
REMOVAL
%
98.9
98.6
96.4
98.4
98.1
97.7
80.4
96.5
98.0
96.9
97.7
82.0
56.1
INFLUENT
SUSPENDED
SOLIDS
(mg/L)
1356
1064
688
1000
412
672
228
776
1060
1140
372
1032
776
EFFLUENT
SUSPENDED
SOLIDS
(lb) (mg/L)
32,120
18,720
10,390
15,350
6,560
9,860
3,730
13,200
17,500
15,880
5,430
13,430
12,430
13
13
18
23
11
18
28
18
32
56
32
344
64
(lb)
310
230
270
350
180
260
460
310
530
780
470
4480
1020
SS
REMOVAL
%
99.0
98.7
97.3
97.7
97.3
97.3
87.7
97.6
96.9
95.0
91.3
66.6
90.7
-------
SAM
TIME (HOURS)
6 7
RAINFALL
• FIGURE -25-f
CHIPPEWA FALLS, WISC.
STORM OF JULY 14,1969
150
100
CFS
T
SAM 678
TIME (HOURS)
DISCHARGE TO POND
82
-------
TIME (HOURS)
9PM 10
MIDNIGHT
12
RAINFALL
FIGURE-26-
CHIPPEWA FALLS, WISC.
STORM OF AUGUST 6,1969
CFS
9PM
DISCHARGE TO POND
TIME(HOURS)
r
12 I
MIDNIGHT
83
-------
2PM
TIME (HOURS)
345
IN.,
HR.
0
1.0
2.0
3.0
4.0
5.0
RAINFALL
FIGURE-27-
CHIPPEWA FALLS, WISC.
STORM OF AUGUST 11,1970
ISO
100
CFS
50
i i
2PM 3 4
TIME (HOURS)
i
5
DISCHARGE TO POND
84
-------
SECTION VII
DISCUSSION OF RESULTS
It may be expected that the BOD^ and suspended solids concentrations
for any given combined sewage overflow would be affected by a number
of factors. The sanitary sewage and waste flow varies in both volume
and characteristics and will obviously have an effect on the charac-
teristics of the combined sewage. The intensity, duration, and total
volume of rainfall, as well as the land use and runoff characteristics
of the drainage area are also expected to be significant factors. A
detailed statistical correlation of the above parameters with the
observed overflow data is not within the scope of this study. However,
a review of the data can provide some indication of the overall
effectiveness of the retention pond system.
The average BOD^ concentrations for the combined sewage discharged to
the pond ranged from a minimum of 43 mg/L on August 11, 1970 to a
maximum of 383 mg/L on September 4, 1969. The August 11 storm
produced 2.63 inches of precipitation and the discharge to the pond
was 527,300 cubic feet. On September 4, 1969 the precipitation was
0.18 inches and the resulting discharge to the pond was 12,900 cubic
feet. The overall average BOD^ of the discharges to the pond for the
entire test period was 150 mg/L. The suspended solids mean concen-
trations ranged from 60 mg/L to 534 mg/L with an overall average of
280 mg/L.
With a few exceptions, the individual samples taken from the combined
sewage discharges to the pond show relatively constant BOD5 and sus-
pended solids values throughout each sampling period. This consistency
may be in part due to the sampling location. The samples were taken
from the wet well of the combined sewage pumping station, and a certain
amount of mixing of,the contents undoubtedly took place. Such 'mixing
may have had the effect of smoothing out any large variations in the
quality of the combined sewage.
With a total pumping capacity of 6000 gpm and an average sanitary sewage
flow of 2000 gpm, the Bay Street pumping station could pump approximately
4000 gpm of storm water to the wastewater treatment plant. A "first
flush" effect could not be observed in this system even if such an
effect were present, since during each storm the initial discharge of
combined sewage was pumped to the wastewater treatment plant.
85
-------
Although a consistent first flush effect was neither expected nor
apparent in the data, there were several discharges to the pond in
which the initial samples were considerably higher in suspended
solids than the subsequent samples. This effect is not nearly as
prominent in the BOD^ data, however. Apparently when large amounts
of solids are washed into the sewers at the beginning of a storm,
the majority of these solids are relatively inert and non-biodegradable.
An extreme example occurred during the storm of August 11, 1970,
when 11,600 pounds of solids were discharged to the retention pond.
Eighteen cubic yards of sand were removed from the pond following
this storm. Some of the sand may have originated at a street
improvement project which was under construction at the time.
A comparison of the three rainfall hyetographs with the suspended
solids data, indicates a correlation between initial rainfall intensity
and initial suspended solids concentration. During the July 14,
1969 storm, the initial intensity was 5.1 inches/hour and the sample
taken after the first five minutes had a suspended solids concentra-
tion of 762 mg/L. The following two storms which overflowed the
pond were lower in initial intensity at 2.1 inches/hour on August 6,
1969 and 0.6 inches/hour on August 11, 1970. The corresponding
suspended solids concentrations were also lower at 232 mg/L and
328 mg/L, respectively.
Since only three pond overflows occurred during the test period,
there is very little data available to evaluate the treatment
effect of the pond. Normally, primary sedimentation is expected
to remove approximately 30 per cent of the BODc and 60 to 70
per cent of the suspended solids in domestic sewage. However,
the storage pond is not designed to be a clarifier. Furthermore,
the characteristics of the combined sewage are so variable that
the degree of treatment to be expected of the pond is not at all
obvious. As shown in Table 16, the three pond overflows vary widely
in the apparent degree of treatment attained. BOD removals ranged
from 22% to 74% and suspended solids removals from 18% to 70%. The
reason for the exceptionally high removals on August 6, 1969 is not
apparent. However, some insight may be gained by examining the time
lag from the start of discharge into the pond to the start of over-
flow to the river. This will give an approximate detention time
for that portion of the total discharge which initially overflowed
to the river. As might be expected, the longest detention time
resulted in the greatest BOD and suspended solids removals. Other
parameters which are usually important in clarifier design are
the overflow rate and the weir rate, However, in the case of a storage
pond in which the discharges are highly variable and of relatively
short duration, these factors are less clearly defined and
controllable. It is clear that both parameters will have higher
values for higher rates of overflow. It is reasonable to expect
that the quality of the effluent would be poorer for higher overflow
86
-------
TABLE 16
TREATMENT EFFECT OF POND DURING OVERFLOWS TO RIVER
STORM OF JULY 14, 1969 , TIME OF OVERFLOW - 6:55 AM - 9:15 AM
VOLUME OF OVERFLOW = 615,800 GALLONS
AVERAGE CONCENTRATION LOAD (LB)
TO POND TO RIVER % REMOVAL TO POND TO RIVER
BOD5 78 mg/L 61 mg/L 21.8
SUSPENDED SOLIDS 253 mg/L 208 mg/L 17.8
2420
7830
310
107
FECAL COLIFORM
(MPN/100 ml)
TOTAL COLIFORM
(MPN/100 ml)
13.1 x 106 20 x 106
112.5 x 106 135 x 106
STORM OF AUGUST 6, 1969
TIME OF OVERFLOW - 12:00 PM - 1:00 AM
VOLUME OF OVERFLOW = 412,000 GALLONS
AVERAGE CONCENTRATION
BOD5
SUSPENDED SOLIDS
TO POND
103 mg/L
269 mg/L
TO RIVER
27 mg/L
82 mg/L
LOAD (LB)
REMOVAL TO POND TO RIVER
73.8
69.5
2760
7210
90
280
STORM OF AUGUST 11, 1970
TIME OF OVERFLOW - 3:30 PM - 5:10 PM
VOLUME OF OVERFLOW = 1,523,000 GALLONS
AVERAGE CONCENTRATION
TO POND TO RIVER
BODc
SUSPENDED SOLIDS
FECAL COLIFORM
(MPN/100 ml)
TOTAL COLIFORM
(MPN/100 ml)
43 mg/L
355 mg/L
3 x 10L
114 x 106
38 mg/L
194 mg/L
3 x 10C
215 x
LOAD (LB)
% REMOVAL. TO POND TO RIVER
11.6 1410 480
45.3 11610 2460
87
-------
rates. This is substantiated by the data to the extent that the
overflow of August 11, 1970 which had the highest recorded peak
and average discharge rates, produced the lowest BOD^ removal
(11.6%). However, the average suspended solids removal (at
45.3%) was higher than that achieved on July 14, 1969 (17.8%).
No significant reduction in the number of total or fecal, coliform
organisms was observed through the pond during the three pond over-
flows. Disinfection was not provided, and the detention time alone
was not sufficient for any substantial die-off to occur.
The maximum daily flow received at the wastewater treatment plant
during the test period was 7.5 mgd on August 7, 1969. On 55 separate
occasions the daily wastewater flow exceeded the design dry weather
flow of 3.2 mgd. Nineteen of these recorded discharges were
greater than 4 mgd. The high combined sewage flows had no apparent
detrimental effect on the operation of the treatment plant.
On days when the influent flow exceeded 4 mgd, the effluent BODc
concentrations averaged 18 mg/L and the suspended solids 23 mg/L.
On August 7, 1969 when 7.5 million gallons were received at the plant,
the effluent BOD5 was 21 mg/L. During April of 1969 the spring
runoff produced four consecutive days when the influent flow exceeded
4 mgd. On the third day of this period, the plant effluent BOD^ was
16 mg/L.
It appears that neither the combined sewage flows from the storage
pond nor those pumped directly from the collection system had any
deleterious effects on the quality of the plant effluent.
The results of the river sampling program shown in Table 17 indicate
very little difference in quality between the two sampling points.
Samples taken following each of the three pond overflows to the river
showed no significant variation from previous or subsequent samples.
Settleable solids data is not included in Table 17 since no measur-
able amount was ever observed.
On August 26, 1970 some floating logs were noticed near the Bridge
Street sampling point upstream of the storage pond. On September 30,
algae and floating scum were observed in the river both upstream
and downstream from the pond. With these exceptions, no floating
material other than ice was noted in the river during the study
period.
In discussing the quality of the Chippewa River, it should be pointed
out that the flow in the river is controlled by two hydroelectric
dams upstream of the retention pond. The upper of the two dams is
located approximately three miles upstream of the pond and forms
88
-------
TABLE 17
CHARACTERISTICS OF THE CHIPPEWA RIVER
DATE
1969
APRIL 10
APRIL 17
APRIL 22
APRIL 29
MAY 1
MAY 13
MAY 20
MAY 22
MAY 27
* ABOVE -
BELOW -
ABOVE
OR *
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
SUSPENDED
SOLIDS
(mg/L)
5.5
25.0
2.4
2.6
1.0
6.0
3.6
2.8
2.0
1.4
1.4
2.6
1.6
1.2
1.2
1.8
3.2
2.4
VOLATILE
SUSPENDED
SOLIDS
(mg/L)
1.0
1.5
0.2
0.6
0.2
3.8
2.0
1.8
1.4
1.0
1.0
1.6
1.0
0.4
0.4
0.6
1.2
1.4
FECAL
COLIFORM
(MPN/
/100 ml)
110
210
0
10
0
40
__
--
10
48
7
8
_-
—
11
18
6
24
TOTAL
COLIFORM
(MPN/
/100 ml)
700
1620
80
420
20
580
-_
__
60
246
54
32
__
--
14
64
25
39
BOD5
(mg/L)
1.9
1.6
0.8
0.9
0.8
0.8
1.4
1.4
1.1
1.5
3.6
4.3
1.7
1.8
1.3
1.4
1.2
1.2
D.O.
(mg/L)
12.6
12.7
11.0
11.0
10.5
10.5
10.3
10.5
9.2
9.3
7.4
7.2
8.9
8.7
8.5
8.6
8.1
8.1
TEMP.
3
2
8
9
9
9
10
10
11
11
15
15
16
16
17
16
18
18
pH
7.05
7.05
6.90
6.95
6.95
7.05
7.10
7.20
7.05
7.15
7.00
7.05
7.40
7.00
7.25
7.15
7.25
7.35
Sampling location upstream of pond
Sampling location downstream of pond
-------
TABLE 17
CHARACTERISTICS OF THE CHIPPEWA RIVER (continued)
DATE
1969
MAY 29
JUNE 3
JUNE 10
JUNE 17
JUNE 24
JUNE 26
JULY 1
JULY 3
JULY 10
ABOVE
OR
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
SUSPENDED
SOLIDS
(mg/L)
3.0
2.4
1.6
1.4
0.8
1.2
1.6
1.8
2.6
2.0
1.4
1.8
3.0
3.4
4.6
6.0
1.8
2.2
VOLATILE
SUSPENDED
SOLIDS
(mg/L)
0.6
0.4
0.4
0.2
0.6
0.6
0.8
0.4
1.6
1.0
1.0
1.4
1.6
1.8
1.6
2.0
1.2
1.0
FECAL TOTAL
COLIFORM COLIFORM
(MPN/ (MPN/ BOD5
/100 ml) /100 ml) (mg/L)
--
--
71
44
15
31
-_
--
58
49
126
31
__
--
-_
--
—
--
--
—
26
59
6
13
__
--
136
112
216
86
__
--
__
--
__
--
0.5
0.7
1.7
2.2
1.2
1.3
1.5
1.4
1.6
1.2
1.7
1.8
1.8
2.6
1.8
2.0
1.9
2.0
D.O.
(mg/L)
7.8
7.9
8.1
8.2
7.2
7.3
6.6
6.7
6.8
6.8
7.9
7.9
8.0
8.1
7.8
8.0
7.2
7.2
TEMP.
18
18
17
16
18
18
20
19
18
18
19
19
20
20
20
20
22
21
PH
7.30
7.35
7.25
7.30
7.20
7.25
7.20
7.30
7.30
7.35
7.40
7.40
7.10
7.30
7.35
7.45
7.40
7.40
-------
TABLE 17
CHARACTERISTICS OF THE CHIPPEWA RIVER (continued)
DATE
1969
JULY 15
JULY 17
JULY 22
JULY 24
JULY 29
JULY 31
AUGUST 5
AUGUST 7
AUGUST 12
ABOVE SUSPENDED
OR SOLIDS
BELOW (mg/L)
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
1.0
0.8
3.0
3.8
2.4
2.8
1.6
2.0
2.4
2.8
1.6
1.4
2.6
2.8
2.3
2.6
1.0
0.8
VOLATILE
SUSPENDED
SOLIDS
(mS/L)
0.6
0.4
2.4
2.2
1.8
2.0
1.0
1.4
1.6
2.2
0.8
0.8
1.4
2.0
1.3
2.1
0.4
0.4
FECAL TOTAL
COLIFORM COLIFORM
(MPN/ (MPN/ BOD5
/100 ml) /100 ml) (mg/L)
--
--
__
—
__
--
40
270
150
40
70
40
10
20
30
60
190
140
--
—
__
—
__
--
20
280
360
460
240
240
320
400
480
380
760
440
1.7
1.7
2.05
2.4
1.8
1.9
1.6
1.6
2.1
2.0
1.8
1.8
2.5
2.7
2.2
2.3
1.9
2.0
D.O.
(mg/L)
6.4
6.4
7.2
—
6.4
6.4
6.1
6.1
6.0
6.0
4.8
4.7
4.4
4.3
4.9
4.7
4.4
4.4
TEMP.
(°C)
23
23
23
23
24
24
24.5
24
25
25
24
23
25
25
25
25
25
25
pH
7.40
7.35
7.40
7.40
7.30
7.35
7.20
7.30
7.25
7.25
7.10
7.15
7.20
7.15
7.30
7.35
7.25
7.35
-------
VD
1-0
TABLE 17
CHARACTERISTICS OF THE CHIPPEWA RIVER (continued)
DATE
1969
AUGUST 14
AUGUST 19
AUGUST 21
AUGUST 26
SEPT . 4
SEPT . 9
SEPT. 11
SEPT. 18
SEPT. 23
ABOVE
OR
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
SUSPENDED
SOLIDS
(mg/L)
1.2
1.0
1.3
1.6
2.2
1.6
1.6
1.8
1.2
1.0
2.6
2.2
1.0
2.6
2.4
4.0
1.4
1.8
VOLATILE
SUSPENDED
SOLIDS
(mg/L)
0.8
0.6
1.0
1.2
1.8
1.2
1.4
1.6
0.8
0.6
2.0
1.4
0.6
1.8
1.6
1.8
0.6
0.8
FECAL
COLIFORM
(MPN/
/100 ml)
90
60
20
--
30
--
—
--
10
30
60
90
—
--
50
70
30
50
TOTAL
COLIFORM
(MPN/
/100 ml)
420
340
120
80
100
180
__
--
20
180
220
240
__
--
100
140
120
200
BOD5
(mg/L)
0.95
1.3
1.2
1.3
1.8
2.0
0.6
1.1
1.0
0.8
1.5
1.6
1.7
1.9
2.4
2.6
1.2
1.5
D.O.
(mg/L)
4.3
4.5
4.8
4.8
4.7
4.7
5.4
5.4
5.7
5.6
6.9
6.9
6.9
6.8
8.2
8.2
8.0
7.9
TEMP.
<°0
25
25
25
25
25.5
25
25.5
25.5
25
25
23
23
21
21
22
22
19
19
PH
7.15
7.25
7.40
7.45
7.10
7.20
7.20
7.20
7.10
7.30
7.25
7.20
7.45
7.60
7.60
7.70
7.40
7.50
-------
TABLE 17
CHARACTERISTICS OF THE CHIPPEWA RIVER (continued)
DATE
1969
SEPT. 25
OCT. 2
OCT. 7
OCT. 9
OCT. 23
OCT. 28
NOV. 13
NOV. 25
ABOVE SUSPENDED
OR SOLIDS
BELOW (mg/L)
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
2.0
2.2
2.6
1.8
1.6
1.8
1.4
1.6
2.2
2.8
2.6
1.4
1.6
2.4
1.6
2.2
VOLATILE
SUSPENDED
SOLIDS
(mg/L)
1.4
1.6
2.0
1.4
1.2
1.4
1.0
1.2
1.8
2.4
2.0
1.0
1.2
2.0
1.4
1.8
FECAL
COLIFORM
(MPN/
/100 ml)
15
25
5
20
--
—
-_
4
18
--
--
13
17
TOTAL
COLIFORM
(MPN/ BOD5
/I 00 ml) (mg/L)
180
140
30
60
_ _
__
—
--
37
42
—
--
29
27
2.5
2.45
0.8
1.3
1.9
1.8
1.6
1.4
1.7
1.9
1.7
1.9
0.35
0.4
0.4
0.5
D.O.
(mg/L)
8.3
8.3
8.3
8.5
9.7
9.4
9.1
9.2
10.3
10.6
9.4
9.6
10.8
10.7
10.4
10.6
TEMP.
(°0
18
18
18
18
16
16
16
10
10
10
9
9
6
6
5
5
PH
7.50
7.60
7.30
7.40
7.40
7.50
7.50
7.55
7.60
7.70
7.60
7.60
7.10
7.30
7.15
7.30
-------
TABLE 17
CHARACTERISTICS OF THE CHIPPEWA RIVER (continued)
DATE
1969
DEC. 4
DEC. 11
DEC. 30
ABOVE
OR
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
SUSPENDED
SOLIDS
(mg/L)
1.2
2.0
1.0
0.8
0.8
9.6
VOLATILE
SUSPENDED
SOLIDS
(mg/L)
1.0
1.0
0.8
0.6
0.6
7.0
FECAL
COLIFORM
(MPN/
/100 ml)
--
59
4
7
24
29
TOTAL
COLIFORM
(MPN/ BOD5
/100 ml) (mg/L)
33
145
124
133
72
57
1.5
1.3
1.7
1.3
1.35
1.2
D.O.
(mg/L)
12.7
12.9
12.4
12.6
13.2
12.4
TEMP.
(°c)
5
4
2
1.5
1
1
PH
7.65
7.5.0
7.35
7.40
7.15
7.35
-------
TABLE 17
CHARACTERISTICS OF THE CHIPPEWA RIVER (continued)
DATE
1970
MARCH 21
MARCH 25
APRIL 1
APRIL 15
APRIL 29
MAY 13
JUNE 3
JUNE 18
JULY 1
ABOVE SUSPENDED
OR SOLIDS
BELOW (mg/L)
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
1.8
1.0
1.2
1.6
1.1
1.5
6.15
6.0
2.0
4.3
2.4
3.1
2.4
2.8
2.0
2.2
2.0
1.8
VOLATILE
SUSPENDED
SOLIDS
(mg/L)
1.4
0.8
1.0
1.2
0.9
1.3
2.25
1.95
1.7
2.0
1.6
1.8
1.4
1.4
1.2
1.4
1.8
1.6
FECAL
COLIFORM
(MPN/
/100 mlO
4
20
14
18
12
16
54
56
3
5
2
4
79
64
44
37
37
198
TOTAL
COLIFORM
(MPN/ BOD5
/100 ml) (mg/L)
108
172
132
240
144
152
161
152
88
56
64
52
352
460
370
410
90
560
0.8
0.7
1.7
1.4
1.8
1.6
2.35
1.65
2.95
3.15
1.45
1.7
1.65
1.8
2.6
2.9
2.0
2.5
D.O.
(mg/L)
9.4
9.6
9.6
9.6
10.3
10.4
11.8
11.8
10.4
10.3
9.4
9.5
8.8
8.6
6.1
6.1
5.9
7.6
TEMP.
(°C)
3
3
2
3
3
3
4
4
15
15
16
16
20
20
23
23
25
25
pH
7.10
7.20
7.10
7.15
6.85
7.00
7.10
7.25
7.10
7.20
7.30
7.50
7.40
7.50
7.20
7.30
7.30
7.30
-------
VO
ON
TABLE 17
CHARACTERISTICS OF THE CHIPPEWA RIVER (continued)
DATE
1970
JULY 15
AUGUST 5
AUGUST 26
SEPT . 9
SEPT. 30
OCT. 15
NOV. 5
NOV. 19
ABOVE
OR
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
ABOVE
BELOW
SUSPENDED
SOLIDS
(mg/L)
2.2
2.4
3.0
2.8
2.4
3.2
1.8
1.8
2.6
2.8
2.2
2.0
2.0
2.0
2.8
2.2
VOLATILE
SUSPENDED
SOLIDS
(mg/L)
2.0
2.3
1.4
1.8
1.8
1.8
1.6
1.4
2.0
2.0
1.8
1.8
1.8
1.8
1.8
1.6
FECAL
COLIFORM
(MPN/
/1 0.0 ml)
87
61
2
8
2
21
2
6
3
1
12
27
__
25
11
18
TOTAL
COLIFORM
(MPN/
/100 ml)
145
120
35
45
65
155
85
105
50
35
45
65
45
225
__
--
BOD5
(mg/L)
3.1
2.4
3.1
2.2
3.7
4.2
3.25
2.70
3.95
3.20
1.50
1.85
__
--
3.45
4.0
D.O.
(mg/L)
6.1
6.1
5.5
5.4
7.0
7.1
7.7
7.5
9.4
9.3
9.7
9.8
10.4
10.4
12.4
12.2
TEMP.
(°0
25
25
26
26
27
27
23
23
18
18
14
14
9
9
4
4
PH
7.00
7.10
7.20
7.30
7.60
7.60
7.40
7.30
7.00
7.20
7.00
7.30
7.05
7.25
5.15
5.05
-------
Lake Wissota as a large storage area. The lower dam is about 800
feet upstream of the pond and 300 feet upstream from the mouth of
Duncan Creek. The two dams are used for flood control as well as
power generation. At certain times of the year the entire river
flow may be temporarily impounded by the dams. Under these
conditions, the only inflow to the river in the vicinity of the
retention pond is from Duncan Creek. During periods of precipi-
tation, Duncan Creek may contain a considerable amount of storm
water runoff from areas of the City which are served by separate
sewers.
Since the combined sewers remain in use in the 90 acre area tri-
butary to the Bay Street pumping station, no data are available
on the quality of separate storm water runoff from the central
business district of Chippewa Falls. However, studies from other
cities (4) have shown mean BOD concentrations in storm water
ranging from 10 mg/L to 147 mg/L, and mean suspended solids
concentrations of 210 mg/L to 2080 mg/L.
The estimated volume of storm water runoff which was withheld from
the river during the two year period was 92.6 million gallons.
Even if the average BOD and suspended solids concentrations in
the storm water were as low as 10 mg/L, the total contribution
of BOD and suspended solids from this volume of separate storm
water would have been considerably greater than the 880 pounds
of BOD and 3810 pounds of suspended solids present in the three
pond overflows to the river.
Prior to the construction of the storage pond, any heavy rainfall
or high water in the Chippewa River would cause extensive basement
flooding in the downtown area. When the pond and associated pumping
facilities were put into operation, the flooding problem was
eliminated.
Of the 62 recorded combined sewage discharges to the pond during
1969 and 1970, 59 discharges (95.2 per cent of the total) were
prevented from reaching the river untreated. On a volume basis,
40.30 million gallons of combined sewage discharged to the pond
during the test period, and 2.55 million gallons overflowed from
the pond to the river. Thus 93.7 per cent of the total volume
discharged was withheld from the river. The 6005 and suspended
solids loads associated with the discharges were 50,400 pounds
and 94,200 pounds respectively. Of these totals, 49,520 pounds
or 98.2 per cent of the BOD,, and 90,390 pounds or 95.8 per cent
of the suspended solids were withheld from the river and sub-
sequently treated. These figures are somewhat conservative
since a small volume discharged to the pond (but not to the river)
while the recorder was out of service and this volume is not
included in the totals.
97
-------
The above results were achieved for a total initial project cost of
$610,067. The estimated cost of complete sewer separation for the
90 acre tributary area was $497,500. The average annual operating
and maintenance cost of approximately $7,300 would have been saved
if complete separation had taken place. However, separation would
not have provided the added benefit of secondary treatment for
nearly all of the storm water runoff from the tributary area.
Furthermore, a separation program would have entailed a longer
construction period than the eighteen months required for the
demonstration project; and the resulting street disruption would
have been much more extensive.
The costs of both constructing and operating a retention pond
system could be considerably reduced if gravity flow was available
from the collection system to the pond and/or the sewage treatment
plant.
98
-------
SECTION VIII
ACKNOWLEDGEMENTS
The support of the Mayor of Chippewa Falls, Wisconsin, Honorable
Clarence C. Rushman, and the entire City Council is acknowledged
with sincere thanks.
Mr. A. W. Banister of Banister Short Elliott Hendrickson & Associates
made the original suggestion for the project and gave counsel and
direction throughout the construction and operation.
The design and supervision of construction of the project was
performed by D. E. Lund of Banister Short Elliott Hendrickson
& Associates.
The project operation and data collection were under the direction
of Clyde Lehman, Superintendent of Public Utilities, at Chippewa
Falls, Wisconsin. His enthusiastic support for the project is
acknowledged with sincere thanks.
Mr. W. R. Liebenow and Mr. J. K. Bieging of Banister Short Elliott
Hendrickson & Associates directed the instrumentation design,
evaluated the collected data, and wrote a major share of the final
report.
Mr. Carl Blabaum of the State of Wisconsin, Department of Natural
Resources, gave valuable support and guidance to the project.
The help provided by Louis J. Breinhurst, Project Officer, is
acknowledged with sincere thanks.
99
-------
SECTION IX
REFERENCES
1. Wells, Jr., Edwin A. and Gotaas, Harold B, "Design of
Venturi Flumes in Circular Conduits'1, Transactions American
Society of Civil Engineers, Vol. 123, 1958, P. 749.
2. Ludwig, John H. and Ludwig, Russell G. , "Design of Palmer-
Bowlus Flumes", Sewage and Industrial Wastes, Vol. 23,
September 1951, P. 1096.
3. Standard Methods for the Examination of Water and Wastewater,
12th Edition, American Public Health Association, New York,
N. Y., (1965).
4. "Storm Water Pollution from Urban Land Activity," Economic
Systems Corporation, Water Pollution Control Research Series,
11034FKL, July 1970.
101
-------
SECTION X
APPENDICES
A. 1969 Wastewater Treatment Plant
Operating Data
Table A-l. Daily Sewage Flow
Table A-2. Hourly Sewage Flow
Table A-3. 5-Day BOD
Table A-4. Suspended Solids
Table A-5. Primary Settling Tank Data
Detention Period
Table A-6. Primary Settling Tank Data
Surface Loading
Table A-7. Secondary Settling Tank Data
Detention Period
Table A-8. Secondary Settling Tank Data
Surface Loading
Table A-9. Aeration Tank Mixed Liquor. .
B. 1970 Wastewater Treatment Plant
Operating Data
Table B-l. Daily Sewage Flow
Table B-2. Hourly Sewage Flow
Table B-3. 5-Day BOD
Table B-4. Suspended Solids
Table B-5. Primary Settling Tank Data
Detention Period
Table B-6. Primary Settling Tank Data
Surface Loading
Table B-7. Secondary Settling Tank Data
Detention Period
Table B-8. Secondary Settling Tank Data
Surface Loading
Table B-9. Aeration Tank Mixed Liquor .
Page No.
103
-------
APPENDIX A. 1969 Wastewater Treatment Plant Operating Data
Table A-l
1969 DAILY SEWAGE FLOW
(Gallons)
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sep.
Oct.
Nov.
Dec.
Total
Average
Maximum
Minimum
TOTAL FLOW
60,263,000
54,679,000
63,069,000
72,973,000
61,147,000
68,579,000
88,277,000
92,427,000
66,812,000
69,236,000
63,168,000
60,256,000
820,886,000
68,407,166
92,427,000
54,679,000
AVE DAILY
1,944,000
1,952,000
2,035,000
2,432,000
1,973,000
2,286,000
2,848,000
2,981,000
2,227,000
2,233,000
2,106,000
1,943,700
2,246,725
2,981,000
1,943,700
MAX DAILY
2,899,000
2,884,000
3,619,000
5,372,000
3,469,000
3,649,000
4,981,000
7,507,000
3,035,000
3,633,000
3,175,000
2,577,000
3,900,000
7,507,000
2,577,000
MIN DAILY
1,401,000
1,370,000
1,384,000
1,330,000
1,079,000
1,236,000
1,922,000
1,330,000
1,622,000
1,673,000
1,599,000
1,387,000
1,444,417
1,922,000
1,079,000
Sewage received from septic tank cleaning service in 1969
totaled 22,460 gallons.
105
-------
Table A-2
1969 HOURLY SEWAGE FLOW
(Gallons)
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
AVE MAX
HOURLY
120, .000
126,000
141,000
185,000
153,000
189,000
195,000
207,000
186,000
165,000
166,000
159,800
166,067
207,000
120,000
AVE MIN
HOURLY
41,000
39,000
49,000
68,000
57,000
58,000
67,000
89,000
59,000
57,000
63,000
64,000
59,250
89,000
39,000
MAX
HOURLY
210,000
210,000
246,000
300,000
240,000
420,000
385,000
420,000
400,000
310,000
360,000
210,000
309,250
420,000
210,000
MIN
HOURLY
18,000
6,000
12,000
12,000
36,000
48,000
60,000
36,000
24,000
36,000
36,000
48,000
31,000
48,000
6,000
106
-------
MONTH
RAW
Table A-3
5 DAY B.O.D.
AVERAGE MONTHLY 1969
(mg/L)
PRIMARY
FINAL
7o REMOVAL
Jan.
Feb.
Mar.
April
M?y
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minumum
-
350
480
345
327
236
229
191
274
279
265
305
298.3
480,
191
-
205
271
171
162
120
129
122
121
134
138
153
156.9
271
120
_
21
45
35
26
21
18,
2,1
19
28
20
24
25.3
45
18
94.0
91.0
88.4
90.9
89.9
92.4
88.6
92.4
88.7
91.9
91.7
90.9
94.0
88.4
107
-------
Table A-4
SUSPENDED SOLIDS
AVERAGE MONTHLY 1969
(mg/L)
MONTH
RAW
PRIMARY
FINAL
REMOVAL
Jan .
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
-
780
959
580
821
730
637
809
894
885
794
700
780.8
959
580
-
226
339
130
170
162
173
370
159
159
148
155
199.2
370
130
-
42
68
38
64
34
28
35
21
35
36
32
39.4
68
21
-
92.9
93.2
92.0
91.0
92.8
95.5
95.2
97.4
95.8
94.2
94.1
94.0
97.4
91.0
108
-------
Table A-5
1969 PRIMARY SETTLING TANK DATA
DETENTION PERIOD
(Hours)
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
AT DAILY
AVERAGE FLOW
11.7
17.4
16.7
14.0
17.3
14.9
12.0
11.4
15.3
15.2
16.1
17.6
14.97
17.6
11.4
AT MAXIMUM
HOURLY FLOW
6.8
7.0
6.0
4.7
9.5
3.4
3.7
3.4
3.6
4.6
3.9
6.8
5.28
9.5
3.4
AT MINIMUM
HOURLY FLOW
78.8
236.6
118.3
118.3
47.3
29.6
23.7
39.4
59.2
39.4
39.0
29.6
71.6
236.6
23.7
109
-------
Table A-6
1969 PRIMARY SETTLING TANK DATA
SURFACE LOADING
(Gal. per square ft. per day)
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
DAILY
AVERAGE
260
261
272
325
264
306
381
399
298
298
282
260
300.5
399
260
MAXIMUM
HOURLY
675
675
790
963
482
1349
1237
1349
1285
996
1157
675
969.4
1349
482
MINIMUM
HOURLY
58
20
39
39
96
154
193
115
77
116
116
154
98
193
20
110
-------
Table A-7
1969 SECONDARY SETTLING TANK DATA
DETENTION PERIOD
(Hours)
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
AT DAILY
AVERAGE FLOW
12.3
12.2
11.7
9.8
12.1
10.4
8.4
8.0
10.7
10.7
11.3
12.3
10.83
12.3
8.0
AT MAXIMUM
HOURLY FLOW
4.7
4.7
4.0
3.3
6.6
2.3
2.6
2.4
2.5
3.2
2.8
4.7
3.65
4.7
2.3
AT MINIMUM
HOURLY FLOW
55.3
166.0
82.9
83.0
33.2
20.5
16.6
27.6
41.5
27.6
28.0
20.9
50.25
166.0
16.6
111
-------
Table A-8
1969 SECONDARY SETTLING TANK DATA
SURFACE LOADING
(Gal. per square ft. per day)
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
DAILY
AVERAGE
146
146
153
183
149
172
215
225
167
168
158
146
169
225
146
MAXIMUM
HOURLY
379
379
445
542
271
759
697
759
724
559
650
378
545.2
759
271
MINIMUM
HOURLY
33
11
21
22
54
86
109
65
43
65
65
86
55
109
11
112
-------
Table A-9
AERATION TANK
MIXED LIQUOR
1969
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
SUSPENDED SOLIDS
(mg/L)
2,396
3,108
1,713
2,657
1,770
1,769
2,240
1,886
1,880
1,853
1,698
2,088
3,108
1,698
S.V.I.
190
150
145
79
83
80
57
100
123
103
142
114
190
57
D. 0.
3.2
2.8
3.7
2.4
2.4
1.4
1.4
1.7
2.2
3.4
2.5
2.46
3.4
1.4
SETTLEABLE
SOLIDS
466
524
261
222
142
146
126
185
253
208
217
250
524
126
113
-------
APPENDIX B. 1970 Wastewater Treatment Plant Operating Data
Table B-l
1970 DAILY SEWAGE FLOW
(Gallons)
MONTH
TOTAL FLOW
AVE DAILY
MAX DAILY
MIN DAILY
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Total
Average
Maximum
Minimum
64,403,000
57,275,000
70,496,000
74,505,000
68,019,000
68,936,000
70,251,000
65,091,000
69,656,000
74,110,000
68,529,000
58,620,000
809,891,000
67,491,000
74,505,000
57,275,000
2,077,530
2,045,535
2,274,065
2,483,500
2,194,161
2,297,867
2,266,161
2,099,710
2,322,000
2,390,645
2,284,300
1,890,967
2,218,870
2,483,500
1,890,967
2,828,000
2,980,000
3,453,000
3,723,000
3,641,000
4,791,000
4,920,000
4,673,000
4,273,000
5,539,000
4,540,000
2,689,000
4,004,000
5,539,000
2,689,000
1,544,000
1,425,000
1,457,000
1,546,000
1,478,000
1,615,000
1,666,000
1,598,000
1,555,000
1,666,000
1,775,000
1,496,000
1,568,000
1,775,000
1,425,000
Total 1969 820,886,000
Average 68,407,166 2,246,725 3,900,000 1,444,417
Sewage received from septic tank cleaning service:
1970 122,660 gallons
1969 22.460 eallons
-------
Table B-2
1970 HOURLY SEWAGE FLOW
(Gallons)
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
AVE MAX
HOURLY
181,548
180,642
184,129
199,266
182,161
180,000
154,903
164,000
183,000
174,967
163,266
127,935
172,985
199,266
127,935
AVE MIN
HOURLY
61,290
48,143
56,870
73,200
58,935
65,600
58,452
62,000
66,000
71,419
71,000
61,677
62,882
73,200
48,143
MAX
HOURLY
310,000
310,000
310,000
310,000
330,000
396,000
420,000
540,000
360,000
420,000
360,000
180,000
353,883
540,000
180,000
MIN
HOURLY
30,000
6,000
6,000
60,000
6,000
54,000
9,600
54,000
54,000
60,000
60,000
58,000
38,133
60,000
6,000
Average 1969 166,067
59,250
309,250
31,000
115
-------
MONTH
RAW
Table B-3
5-DAY B.O.D.
AVERAGE MONTHLY 1970
(mg/L)
PRIMARY
FINAL
% REMOVAL
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
347
231
276
319
269
282
318
301
346
287
403
440
318
440
231
195
154
172
169
149
168
203
193
216
160
252
264
191
264
149
25
23
27
23
26
26
27
24
16
9
11
42
23
42
9
93.0
88.9
90.3
91.7
90.0
89.2
90.6
92.0
93.4
95.8
96.5
89.1
91.7
96.5
88.9
Average 1969 298
157
25
90.9
116
-------
,Table B-4
SUSPENDED SOLIDS
AVERAGE MONTHLY 1970
(mg/L)
MONTH
RAW
PRIMARY
FINAL
% REMOVAL
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
807
676
922
1,070
638
905
816
628
648
598
744
618
755
1,070
598
435
406
381
445
260
442
383
312
275
213
422
433
367
445
213
30
38
33
33
26
24
24
32
24
17
14
67
30
67
14
96.0
90.5
95.3
96.1
95.4
95.3
96.0
94.3
95.6
97.0
97.7
91.1
95.0
97.7
90.5
Average 1969 781
199
39
94.0
117
-------
Table B-5
1970 PRIMARY SETTLING TANK DATA
DETENTION PERIOD
(Hours)
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
AT DAILY
AVERAGE FLOW
16.4
16.6
14.9
13.0
15.5
14.8
15.0
16.2
14.7
14.3
14.9
18.0
15.4
18.0
13.0
AT MAXIMUM
HOURLY FLOW
4.5
4.5
4.5
4.5
4.3
3.6
3.3
2.6
3.9
3.4
3,9
i
7.8
4.2
7.8
2.6
AT MINIMUM
HOURLY FLOW
47.3
236.6
236.6
23.6
336.7
26.3
148.0
26.3
26.3
23.7
23.6
24.4
89.9
236.7
23.6
Average 1969
15.0
5.3
71.6
118
-------
Table B-6
.1970 PRIMARY SETTLING TANK DATA
.SURFACE LOADING
(Gal. per square ft. per day)
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
DAILY
AVERAGE
278
274
304
332
294
308
303
281
311
320
305
253
297,
332
253
MAXIMUM
HOURLY
996
996
996
996
1,060
1,272
1,349
1,736
1,157
1,349
1,156
578
1,137
1,736
578
MINIMUM
HOURLY
96
19
19
193
19
171
31
174
174
193
192
186
122
193
19 .
Average 1969
301
96,9
98
119
-------
Table B-7
1970 SECONDARY SETTLING TANK DATA
DETENTION PERIOD
(Hours)
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
AT DAILY
AVERAGE FLOW
11.4
11.6
10.5
9.6
10.9
10.4
10.5
11.4
10.3
9.9
10.4
10.0
10.6
11.6
9.6
AT MAXIMUM
ROURLY FLOW
3.2
3.2
3.2
3.2
3.0
2.5
2.3
1.8
2.8
2.4
2.7
5.5
3.0
5.5
1.8
AT MINIMUM
HOURLY FLOW
33.1
165.8
165.8
16.5
165.8
18.4
104.0
18.4
18.4
16.6
16.5
17.1
63.0
165.8
16.5
Average 1969
10.8
3.7
50.3
120
-------
Table B-8
1970 SECONDARY SETTLING TANK DATA
S.URFACE LOADING
(Gal.per square ft. per day)
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
.DAILY
AVERAGE
156
154
171
187
165
173
170
150
175
180
172
142
166
187
150
MAXIMUM
HOURLY
559
559
559
559
596
715
758
974
649
758
649
325
638
974
325
MINIMUM
HOURLY
54
11
11
108
11
96
17
97
97
108
108
105
69
108
11
Average 1969
169
545
55
121
-------
Table B-9
AERATION TANK
MIXED LIQUOR
1970
MONTH
Jan.
Feb.
Mar.
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Average
Maximum
Minimum
SUSPENDED SOLIDS
(mg/L)
3,458
3,150
3,929
4,342
4,136
4,231
4,064
2,983
3,981
3,606
4,241
5,055
3,931
5,055
2,983
S.V.I. D.O.
134 2.5
84 2.9
91 2.3
92 2.5
100 1.4
86
89
75
93
119 1.4
151 1.5
170 2.4
107 2.1
170 2.9
75
SETTLEABLE
SOLIDS
471
279
364
404
417
359
360
227
228
446
648
856
422
856
227
Average 1969
2,088
114
2.5
250
122
U.S. GOVERNMENT PRINTING OFFICEH972 514-149/75 1-3
-------
1
Accession Number
w
2
Subject Field & Group
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
| Organization
Banister Short Elliott Hendrickson & Associates, St. Paul, Minnesota
6 ri
Storage and Treatment of Combined Sewer Overflows
IQ Authors)
Liebenow, Wilbur, R.
Sieging, James, K.
Project Designation
EPA, WQO Contract No. 11023 FIY
2] I Note
22
Citation
Environmental Protection Agency report
number EPA-R2-T2-070, October 1972,
Descriptors (Starred First)
Overflow*, Rainfall-Runoff Relationships*, Sewage Treatment*, Storm Runoff*, Waste
Storage*, Activated Sludge, Capital Costs, Design Storm, Maintenance Costs, Operating
Costs, Precipitation Intensity, Sedimentation, Sewage, Water Quality
Identifiers (Starred First)
Combined Sewers*, Detention Pond*, Chippewa Falls*, Wisconsin*, Chippewa River*
27 I Abstract •
~^~^ The objective of this study was to demonstrate the feasibility and economic effective-
ness of a combined wastewater overflow detention basin.
A paved asphalt detention basin with a storage volume of 8.66 acre feet was constructed
at Chippewa Falls, Wisconsin to receive overflow from a 90 acre combined sewer area including
all of the central business district. The system was designed so that the stored combined
sewage could be pumped to the wastewater treatment plant when precipitation subsided.
During 1969, due to dry weather, the pond received only sixteen discharges, but
completely filled twice and overflow to the river occurred. During 1970, there were 46
discharges and the pond filled once overflowing to the river. Over the two year period,
37.75 million gallons of combined sewage (93.7 per cent of the total discharge volume) were
withheld from the river for subsequent treatment.
There were no observed detrimental effects on treatment plant operation due to the in-
creased intermittent flows from the detention pond. The estimated cost of operating and
maintaining the pond and associated facilities was $7,300 per year for the two year period.
Capital costs were $6,780 per acre of drainage area including some relief combined sewer
and increased size of units at the waste water treatment plant.
Abstractor
Wilbur
WR:I02 (REV. JULY
R,
1969)
Liebenow
Institution
Banister
Short
Elliott
Hendrickson
&
Associates
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D. C. 20240
------- |