United States
Environmental Protection
Agency
vEPA
Great Lakes National
Program Office
536 South Clark Street
Chicago, Illinois 60605
EPA-905/2-85-001 -A
September 1985
In-System Storage
Controls For Reduction
Of Combined Sewer
Overflow - Saginaw, Michigan
Executive Summary
Do not WEED. This document
retained in the EPA
5 Library CoB.ect.on.
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EPA-905/2-85-001-A
September 1985
IN-SYSTEM STORAGE
CONTROLS FOR REDUCTION
Of COMBINED SEWER OVERFLOW
SAGINAW, MICHIGAN
William C. Pisano, P.E.
Daniel J. Connick
Gerald L. Aronson
ENVIRONMENTAL DESIGN & PLANNING, INC.
369 Winter Street
Hanover, Massachusetts 02339
Grant No. S005359
for
DEPARTMENT OF PUBLIC UTILITIES
CITY OF SAGINAW
SAGINAW, MICHIGAN
Ralph G. Christensen Richard Traver
Project Officer Technical Assistance
U.S. Environmental Protection Agency
Region 5, Library (PL-12J)
77 West Jackson Boulevard, 12th floor
Chicago, II 60604-3590
GREAT LAKES NATIONAL PROGRAM OFFICE
U.S. ENVIRONMENTAL PROTECTION AGENCY
536 South Clark Street
Chicago, Illinois 60605
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Disclaimer
This report has been reviewed by the Great Lakes National
Program Office, U.S. Environmental Protection Agency and approved
for publication. Approval does not signify that the contents
necessarily reflect the views and policy of the USEPA, nor does
mention of trade names or commercial products constitute
endorsement or recommendation for use.
ij*$l 4H^
-ft
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FOREWORD
This report overviews the results of a recently
completed five-year combined sewer overflow (CSO) control program
in Saginaw, Michigan (10,000 acres, pop. 85,000) funded by City
of Saginaw/U.S. EPA 108 Great Lakes National Program and
conducted by the engineering contractor. Environmental Design and
Planning, Inc., Hanover, Mass. The implemented control program
entailed modification of 13 combined sewer regulation chambers
together with construction of one new in-line control chamber to
maximize transient system storage of wet weather combined
sewerage for later bleedback to a well-operated Wastewater Treat-
ment Plant (WWTP) having phosphorous removal and ample treatment
capacity. These improvements, "the reduced Best Management
Practices (BMP) plan", represent a partial completion of the
first of two phases of the City's CSO Facility Plan. The
objective of Phase I was to maximize WWTP processing of wet
weather combined sewage generated using inexpensive transient
system storage (less than $l/cu.ft.) so as to minimize the
extent, scale and cost of satellite CSO treatment facilities
(Phase II). The swirl concentrator technology was recommended to
treat residual overflows remaining after Phase I improvements.
Six major facilities were recommended and adopted as part of the
CSO Facility Plan.
The total cost of the implemented program including
engineering was $.504 million (1984). A post construction
evaluation measurement/modeling program was conducted in the
Fall, 1984 to verify preproject design conditions. It has been
determined that implementation of the reduced BMP plan has
increased the percentage of total annual wet weather flow
directed to the WWTP by 14.6% (from a previous "as is" level of
37.7%) and has incrementally reduced (beyond "as is" levels)
suspended solids loadings to the Saginaw River by 16%, BOD by 20%
and total phosphorous by 8.5% (secondary treatment). During
periods of advanced wastewater treatment (AWT)(pickling liquor
addition) at the WWTP, total phosphorous removals have increased
to 12.6% above pre-implementation levels. Implementation of the
remaining elements of the complete BMP plan (Phase I) will pro-
duce an overall incremental wet weather flow increase of 30%
(increasing the total wet weather flow treated at the WWTP to
67.7%).
This project was funded by U.S. EPA in part, to demon-
strate new innovative full scale approaches for mitigating CSO
impacts on the Great Lakes. The primary project justification
was to develop and document an innovative, inexpensive and cost-
effective management approach for mitigating wet weather
phosphorous loadings to Saginaw Bay (Lake Huron). The results are
currently being used as part of U.S. EPA's joint efforts with
Canada to develop phosphorous limitation management strategies.
111
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In addition, the results of this demonstration project will
provide valuable insights for a number of projects in the forma-
tive preliminary phase investigating in-system storage management
to "clip" or eliminate CSO from small intensity, high frequency
events as an inexpensive and cost effective control measure.
This report was submitted in partial fulfillment of
Grant No. S005359 by Environmental Design & Planning, Inc. spon-
sored by a Section 108 grant from the Great Lakes National
Program Office, Region V, U.S. EPA with funds also from the City
of Saginaw. This report covers a period of September, 1979 to
December, 1984 and work was completed as of April, 1985.
IV
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TABLE OF CONTENTS
Foreward iii
Chapter 1: Description of City of Saginaw Sewerage
Conveyance and Treatment Facilities
1.1 Introduction 1
1.2 Sewerage System Overview..... 1
1.3 WWTP Details 5
Chapter 2: Combined Sewer Overflow Control (1960-1978)
2.1 Prior CSO Facility Plan 7
2.2 Hancock Street Storage/Treatment Facility 7
Chapter 3: Combined Sewer Overflow Control (1979-1985)
3.1 Rationale for Replacement of
CSO Facility Plan 11
3.2 Overview: 108 Demonstration Grant 11
3.3 Phase 1: 108 Demonstration Project 12
3.3.1 New CSO Facility Plan - Phase 1 14
3.4 Description of Three Efforts to Develop
the Demonstration Project - Phase 1 18
3.5 Phase 2: 108 Demonstration Project 22
3.6 Phase 3: 108 Demonstration Project 27
Appendix A: 108 Demonstration Project Conclusions 29
Appendix B: 108 Demonstration Project Recommendations 33
References.
35
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LIST OF FIGURES AND TABLE
Figure
1 Location of Saginaw, Michigan 2
2 Saginaw Combined Sewer Service Area 3
3 General Plan of Interceptor Sewer System 4
4 Location of CSO Storage/Treatment Basins 8
5 Hancock Street Storage/Treatment Facility
Implementation 10
6 Effectiveness of Overall Preliminary Plans 13
7 Proposed EDP CSP Plan 15
8 Layout of Weiss Street Combined Sewer
Overflow Treatment Complex 19
9 Weiss Street Overflow Water Storage
Facility • 21
10 Webber Street Swirl Facility 23
11 Details of Reduced BMP Plan 25
12 Salt and Vermont Streets Chamber 26
Table
1 Comparison of Recommended Plan and
Alternative Plan 16
VI
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ACKNOWLEDG EMENTS
The authors would like to commend the EDP staff who
worked so hard to make this program a success. Through the
diligent efforts of many, a study has been prepared assessing
the viability of a relatively new technology for solving a
complex combined sewer management problem in the City of Saginaw.
We would like to thank the City of Saginaw Public
Utilities Department for their extreme cooperation and good will,
including Robert Dust, Executive Director of Public Utilities,
Mr. Jim Anderson, Superintendent and Fred Schulze, Assistant
Superintendent, Wastewater Treatment Division.
We would like to also thank Mr. Ralph G. Christensen,
U.S. EPA Region V, Great Lakes National Program Office, for his
support and assistance. The Great Lakes Program provided funds
for this project. In addition, Mr. Richard P. Traver, U.S. EPA,
Edison, New Jersey was extremely helpful in coordinating the
early phases of the project.
Finally. we would like to express our sincerest
appreciation to Ms. Eunice Harris for her patience in typing this
report.
Environmental Design & Planning, Inc. was the
engineering contractor for his project. Dr. William C. Pisano,
P.E., President, EDP, was the principal investigator. Mr. Daniel
J. Connick, Sr. Design Engineer, was the project manager. Mr.
Gerald L. Aronson, Executive Vice President, EDP, supervised
field monitoring and evaluation efforts.
Vll
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CHAPTER 1
DESCRIPTION OF CITY OF SAGINAW SEWERAGE
CONVEYANCE AND TREATMENT FACILITIES
Section 1.1 Introduction
Saginaw is located in the eastern part of central
Michigan, north of Detroit, as shown in Figure 1. The Saginaw
River is a short section of a major drainage area leading to
Saginaw Bay, Lake Huron. The topography of the area is flat.
The Saginaw River about evenly divides the 10,437 acre area of
the City of Saginaw. The Saginaw River drainage basin above the
City has an area of 6,200 sg. mi.
The area which is surrounded by the Great Lakes, has a
quasi-marine environment. Saginaw1s normal annual precipitation
is about 28.6 in., over 50% of which falls during the summer
between March and September. Beginning in March or April, melting
snow combined with rainfall can produce high overflow volumes to
the river. Most of the storms that occur are of low average
intensity. Over 90% of the time, the average intensity of rain-
fall which produces runoff is less than 0.10 in./h.
The City of Saginaw is serviced by a combined sewer
system. Combined sewer overflows (CSO) during rain events are
contributors of pollutants to the Saginaw River. Overflows may
occur at 34 regulator chambers. Five pump stations are designed
to relieve the system during flooding conditions. See Figure 2.
It is estimated that over 60 overflows occur per year.
Impacts on the Saginaw River from CSO include dissolved
oxygen depletion in the downstream segments of the river and
floatable material may create visual problems. Nutrient
emissions, particularly dissolved phosphorous, are critical
concerns to Saginaw Bay and Lake Huron.
Section 1.2 Sewerage System Overview
The intercepting sewer shown in Figure 3 runs along both
banks of the Saginaw River. The West Side Interceptor crosses the
river at Weiss Street to join the East Side Interceptor, which
continues to the WWTP at the northeast limits of the City.
Because a number of the sewers are below flood river
stage, the problem of collecting sewage may involve stormwater
pumping during periods of high river level. During flood river
levels, storm flows will discharge over the regulator chamber
weirs into the intercepting system. Backwater gates prevent
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•ILIAUKEC
CM ICICt
ILLINOIS
i i
1 INDUNM
\
OH I 0
Figure 1 Location of Saginaw, Michigan.
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OJ
LEGEND.
9 EXISTING pyMPiNr. STATION
A CHAMBER
EXISTING INTERCEPTOR
EXISTING COMBINED SEWER
*NQ OVERFLOW TYPICAL)
— .— CITY LIMITS
LIMITS Of SERV'CP *»CA
OUTSIDE ft* i
HANCOCK ST PUMPING
STATION
see
INTERCEPTOR
V»EB8E" 51
STATION
WEISS si.PUMPING
STATION
EMERSON si PUMPING
STATION
EA'.T SIDE
INTERCEPTOR
EXISTING
W*STE
PUMPING STATION
Figure 2 Soginow combined ttwtr tarviee oreo.
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SCALE (fh«MM4ieffort)
0123
Swoga pumping stati
andtrwtfmntplont
EAST SIDE INTERCEPTOR
Enwrwn St
pumping station
WEST SIDE INTERCEPTOR
nnVSS 9t<
pumping station
Figure 3 General plan of interceptor sewer system.
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discharge of flood river water into the sewerage system. Flood
pumping stations are located at Webber, Emerson, and Fourteenth
Streets on the East Side, and Hancock and Weiss Streets on the
West Side.
The interceptor system serves the dual purpose of
collecting sewage and carrying storm flows and consists of tunnel
sewers ranging from 42 to 78 inches in diameter. The tunnels
are approximately 40 feet below ground level.
Section 1.3 Wastewater Treatment Plant (WWTP) Details
The City's 32.7 rogd secondary WWTP is located on the
east bank of the Saginaw River. Wastewater enters the plant in a
72-inch interceptor sewer. After screening and grit removal, the
wastewater is settled in four primary sedimentation tanks.
Primary effluent passes into the conventional activated sludge
system where ferrous sulfate or waste pickle liquor can be added,
for phosphorus removal as necessary to meet effluent discharge
standards. Final effluent is chlorinated before discharge to the
Saginaw River. The current NPDES permit for the plant requires
that monthly average BOD and suspended solids concentrations not
exceed 25 and 30 mg/1, respectively. Effluent total phosphorous
concentrations must be less than 1 mg/1.
Prior to 1968 sewage discharging from the City of
Saginaw was given primary treatment with chlorination. The
primary plant was then upgraded to secondary treatment including
biological activated sludge with phosphorous removal. Although
the modified plant is designed for a nominal flow of 50 cfs and
an estimated maximum flow of 128 cfs, the secondary treatment
unit operations are sized for about 160 cfs discharge. All storm
flows entering the WWTP in excess of 108 cfs are split at the
grit chamber with bypass receiving only chlorination. Currently,
bypass beyond 108 cfs occurs at a spillover weir such that
increasing influent flow rates results in simultaneous increased
flow through the plant and increased bypass. The average dry
weather flow is about 32 cfs.
All flow beyond the grit chambers receives full
treatment. There are four secondary aeration tanks following the
primary clarifiers. Normally two aeration basins are used for
dry weather flow and wet weather discharges up to about 84 cfs.
The two other aeration basins are used as storage (0.5 million
cubic feet) for wet weather discharges above 84 cfs. If these
basins are filled, flow- through conditions result. The storage
contents after an event (or when influent rate significantly
decreases) of these two tanks containing primary treated wastes
then receive full primary/secondary treatment as these volumes
are pumped back to the headworks. Any flows beyond 84 cfs and in
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excess of the two aeration tank storage volume will receive
primary treatment, limited aeration with phosphorous removal (if
necessary), secondary clarification and disinfection.
Average suspended solids and BOD influent
concentrations are reduced by 93% and 89% respectively. Total
phosphorous effluent concentrations do not exceed 1 mg/1.
Analysis of long-term plant efficiency records indicate little
deviation from average removals during wet periods.
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CHAPTER 2
COMBINED SEWER OVERFLOW CONTROL (1960-1978)
Section 2.1 Prior CSO Facility £lan
Abatement of CSO pollution was required to comply with
order issued by State of Michigan Water Resources Commission
(1960) . Several studies focusing on the CSO problems were
completed (1) to meet the requirements of the order. A control
plan was accepted in 1969. The basic concept consisted of utili-
zing to its maximum the existing system together with seven new
storage and treatment facilities at locations determined by the
hydraulics of the system. See Figure 4. The intent was to make
the best use of existing facilities, and to preserve the flood
protection function of the existing interecepting and flood
pumping system. The storage and treatment concept was considered
to be the state-of-the-art CSO technology at that time.
The CSO control plan entailed the following design
parameters: a) every overflow would be disinfected; b) the pro-
posed facilities would provide the equivalent of primary treat-
ment for events up to design storm (1 year) conditions; c) after
storms the stored sewage and settled solids would slowly be
bledback to the WWTP for final treatment; and d) the entire
system would revert to its normal flood protection function
during river flood stage.
The plan focused on utilizing in-line and off-line
storage. Approximately 18 million gallons (mg) of in-system
storage was determined to be available for retention/attenuation
of combined sewage through modification of regulators, construc-
tion of weirs, restraining of tide gates and other means. In
addition, over 18 mg of off-line storage at seven locations was
recommended to be constructed to retain and treat wet weather
flows in excess of the collection and transmission system's
hydraulic capacity. Disinfection was recommended to be provided
by injection of chlorine into the influent conduits of each
storage basin with a minimum contact time of 15 minutes. Costs
for construction of seven off-line storage/treatment facilities
(excluding multi-purpose use considerations) and including in-
line storage control improvements are estimated to equal $80.6
million (ENR=4500)(2).
Section 2.2 Hancpck Street Storage/Treatment Facility
During the mid 70's the first element of the CSO plan
was implemented. In 1977 the existing Hancock Street Flood
Pumping Station was modified to include a 3.6 mg storage/treat-
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exisriNO PUMPING STATION
. EXISTING REGULATION
A CHAMBER
EXISTING INTERCEPTOR
_._ CITY LIMITS
EXISTING COMBINED SEWER
AND OVERFLOW(TYPICAL)
Of SERVICE AREA
OUTSIDE CITY LIMITS
EXISTING HANCOCK ST
STORAGE BASIN
STORAGE BASINS
HANCOCK ST
STATION
EXISTING STORAGE
BASIN
WEBBER si PUMPING
STATION
WEISS ST PUMPING
STATION
EMERSON ST PUMPING
STATION
EAST SIDE
INTERCEPTOR
EXISTING
WASTE WATER
TREATMENT
PLANT
FOURTEENTH si
PUMPING STATION
Figure 4 Location of CSO storage/treatment basins.
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ment facility. The existing pumping station was upgraded to
include electric-driven pumps. A multi-purpose underground stor-
age/treatment facility with above ground municipal parking was
constructed. Excluding garage and in-system modification improve-
ments, the capital costs (ENR=4500) of the facility equalled
$10.4 million. In-line storage potential of the combined sewers
in the Hancock Street area was increased by modifying the
existing static regulators in the system. Capital costs
(ENR=4500) of the in-line control improvements in the Hancock
Street catchment area equalled $.56 million. See Figure 5.
Modifications to the regulators included replacing the tide gates
at the outfall with motor-operated sluice gates to increase the
maximum storage capacity of the system.
During the storm events, combined flows diverted to the
interceptor by the regulators activate the Hancock Street pumping
station as the interceptor flow level increases. Sluice gates
between the interceptor and the pumping station wet well open
automatically and pumping is sequentially controlled by sensing
the wet well water elevations. All flows to the storage/treat-
ment basins are pumped. During extreme river flooding, the
station can be pumped directly to the river bypassing the
retention basin.
Combined flows pumped to the Hancock Street facility
sequentially fill a series of paired basins. The facilities
operate under two types of storm flow conditions: a) for 1 year
design storm, the flow will be captured and totally stored, with
subsequent release to the interceptor as capacity becomes
available; and b) for storm events producing flow exceeding the
basin storage capacity, the system will store and treat the
combined flow by sedimentation with disinfection of overflow
before discharge to the river.
To date, the success of the overall detention/chlorina-
tion facility concept has been mixed. Construction costs for the
Hancock Street facility exceeded estimates by roughly one million
dollars. Suspended solids treatment efficiencies have ranged from
35 to 92%. Chlorination equipment has been inoperative since
construction. Recently, severe operating difficulties during
intense rainstorms have arisen due to the motor-operated sluice
gates in the Hancock Street catchment area. The sluice gates
open or close in a finite period of time. If the gates do not
open to permit rapidly developing peak flows to overflow, then
severe surcharge problems result.
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EXISTINO PUMPWO STATION
EXISTWC REGULATION
CHAMBER
CXItTINO IMTCTCfPTO*
_._ CITY LIMITS
LIMITS OF SCftVICC AREA
OUTSIDE CITY LIMITS
PROPOSED
STORAGE BASINS
Elements completed
in 1977
EXISTING COMBINED SEWER
AND OVERFLOWCTYWCAL)
. HANCOCK ST.
STORAOE IASIN
HANCOCK ST. PUMPING
STATION
WEBBER ST
STATION
WEISS ST. PUMPING
STATION
EMERSON ST. PUMPING
STATION
EAST SIDE
INTERCEPTOR
EXISTINO
WASTE WATER
TREATMENT
PLANT
; FOURTEENTH ST.
LIMPING
Hancock Street Storage/Treatment Facility Implementation
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CHAPTER 3
COMBINED SEWER OVERFLOW CONTROL: 1979 - 1985
Section 3.1 Rationale for Replacement of CSQ Facility Plan
During the late 70's developments in CSO abatement
technology indicated the potential for treatment of excess wet-
weather flows through application of high-rate processes. These
high-rate processes were shown to result in the removal of
pollutants (especially solids) at an efficiency equivalent to
"low end" primary treatment at a fraction of the cost of
conventional facilities. One such device is the swirl
concentrator, which has been demonstrated to achieve over 40%
"first flush" suspended solids removal and a significantly larger
fraction of floatables (3).
In view of these new technological developments and the
rising inflationary costs of both the envisioned storage and
treatment construction programs and the ensuing high degree of
operational requirements already experienced, the City of Saginaw
applied for, and received a Section 108 grant from the U.S. EPA
108 Great Lakes National Program, Region V. The grant is
entitled, "Demonstration Grant for Control and Treatment of
Stormwater from Combined Sewer Overflows in Saginaw" and was
funded to implement and evaluate on a full-scale basis new inno-
vative low-cost technologies for mitigating CSO discharging from
the City of Saginaw sewerage system into the Saginaw River. The
108 Program and subsequent funding was established when Public
Law 92-500 came into existence for the purpose of demonstrating
promising technologies for abating CSO and stormwater pollution
impacting the Great Lakes. Approximately $1.1 million was allo-
cated to the project. Environmental Design & Planning, Inc.
(EDP) was the engineer for the project.
Section 3.2 Overview: 108 Demonstration Grant
The project progressed from 1979 until 1985, culminating
with implementation and evaluation of a number of system
improvements. The overall work effort consisted of three
separate phases. Within Phase 1 EDP prepared a feasibility study
in which the most cost effective .means of treating CSO using new
state-of-the-art technology were established. During this phase
a CSO Facility Plan was developed and adopted as well as
recommendations for implementing a demonstration project.
Several promising demonstration projects were proposed and
detailed but the costs exceeded available grant monies. In 1983
(Phase 2) a further investigation was prepared due to a lack of
supportive 201 funds to implement several elements of the adopted
11
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CSO Facility Program. Phase 2 efforts were directed at
optimizing a reduced scope of work plan for implementation using
available funds. In Phase 3 these proposed improvements were
designed, implemented and evaluated.
Section 3.3 Phase lj 108 pemonstration Project
The objectives of the Phase 1 (1979-1981) EDP study
were twofold: a) preparation of an alternative overall framework
plan for the management of CSO from the City of Saginaw
considering, but not limited to, the existing concepts of storage/
treatment/chlorination facilities; and b) preparation of a
detailed preliminary plan for a portion of the envisioned city-
wide plan, entailing implementation of a full-scale demonstration
treatment facility devised in such a way that it would form a
logical element of the overall CSO Facility Plan.
Runoff simulation studies indicated that the two most
effective measures for handling CSO were increased wet weather
loadings to the City's WWTP and inclusion of actions termed,
"Best Management Practices" (BMP). The BMP program consists of
extensive in-line storage and system modifications to increase
hydraulic capacity so that the WWTP can handle more wet weather
combined sewage. Roughly 2 million cubic feet of new in-line
system storage would be generated as a result of this plan.
Estimated capital cost of BMP plan equalled $2.7 million
ENR=4500) .
After implementation of the complete BMP plan, CSO's for
heavy to moderate storm events would still remain at six
locations: Weiss Street Pump Station, Weiss Street gravity line,
Emerson Street Pump Station, Fourteenth Street Pump Station and
gravity line (handled as a composite), Webber Street Pumping
Station and the Fraser Street Regulator. Swirl solids
concentrating facilities were recommended at these locations as
the most cost-effective technology for treating these overflows.
Optimization analysis of various swirl configurations/sizes at
the various overflow points (after implementing the BMP program)
resulted in pin-pointing the Weiss Street area as the most
significant location for a major swirl concentrator facility.
Although the proposed BMP program elements were the most
cost-effective means for abating CSO in Saginaw (see Figure 6),
U. S. EPA desired at that time to implement and to conclusively
evaluate the effectiveness of the swirl concentrator technology
for reducing CSO pollutant loadings. The 24-foot diameter swirl
concentrator (design flow - 40 cfs) in Lancaster, Penn. showed
significant promise as a new inexpensive technology in comparison
to sedimentation/detention for reducing CSO settleable solids and
floatables. Although the suspended solids removal results,
12
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% REMOVALS *
100-
80-
60 -
40 -
20 -
* % Removals based on
totol wet weather load to
river assuming WWTP
handled only DWF.
• Swirl plans
O TSS]
O 8001
A Other system improvements
itaroge basin plan
O
O
"RT"- WWTP Handling Wet Weather Flows
"RTH"- Addition of Hancock St. Facility
"BMP"- Addition of In-Line Storage Program
to "RTH"
"S./.."- Addition of various Swirl Configur.
to "BMP"
"H" - Prior Storage/Treatment Plan (Complete
"Low Rainf: Total rainfall per event less than or equal to 0.5 inch
"High Rain": Total rainfall per event greater than 0.5 inch
( 1979 rainfall data: 78 events )
T~
RT
RTH
BMP
\
SI /SID
S2/S20
1
S3/S3D
1
S4/S40
1
S5/S50
S6/S60
Plans
Figure 6 Effectiveness of overall preliminary plans.
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particularly during "first flush" conditions, were extremely
favorable the evaluation program was plagued with numerous flow
measurement instrumentation problems. Since a number of swirl
concentrators were being incorporated into designs throughout the
U. S. at that time, U.S. EPA believed that the proposed
evaluation program at Saginaw would answer any unresolved
questions remaining from the Lancaster experience. It was also
desired by U.S. EPA at that time to construct and evaluate a
swirl concentrator of larger physical dimensions than the device
at Lancaster to expand the evaluation experience for this
emerging technology.
The Phase 1 study (4) recommended three alternative
swirl concentrator demonstration facilities located at the Weiss
Street gravity overflow, at the Weiss Street Pump Station
discharge and at the gravity discharge at Fourteenth Street. The
facility at the Weiss Street gravity overflow was preferred.
Section 3.3.1 New CSQ Facility Plan r. Phase 1
Because of the significant cost savings associated with
the City-wide CSO control program reported during the Phase 1
feasibility study and as a mechanism to facilitate Section 201
Construction Grants funding to partially support the costs of the
proposed demonstration project at Weiss Street, EDP was
instructed in mid 1980 to expand the Phase 1 study into a
proposed CSO Facility Plan for the City of Saginaw (5). In
January, 1981 the proposed CSO Facility Plan was adopted by the
City of Saginaw and is depicted in Figure 7. A comparative
overview of the new CSO Facility Plan with the prior
storage/treatment program is depicted in Table 1.
The major components of the adopted CSO Facility abatement
program are as follows:
A: BMP program implementation
B: Swirl Concentrator Facilities at:
Design Capacity
Weiss Street Pump Station 300 cfs
Weiss Street Gravity Line 100 cfs
Emerson Street Pump Station 300 cfs
Fourteenth Street Pump Station* 50 cfs
Webber Street Pump Station 50 cfs
Fraser Street 50 cfs
* Also Gravity Discharge Line
14
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LEGEND
EXISTING INTCMCCPTON
LIMITS OF SEKVICC
OUTSIDE CITY LIMITS
PROPOSED REGULATOR
MODIFICATIONS:
PROPOSED INUNC FLOW
CONTROL/STORAGE DEVICE
I Imi r nrW
noncocK
Storage/Treatment Facility
^
• TYPE A
A TYPES
Proposed
Webber SI
Swirl Facility
St. pumping station
r-> weir increase
*|*-Prooosed Weiw
twirl facility (swirl dtgrittv)
EXISTING
WASTE WATEM
TREATMENT
PLANT
Proposed Fourteenth St
swirl focilily
TYPICAL EXISTING
SEWER LINE
Figure 7 Proposed EDP CSO ptan.
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TABLE 1
COMPARISON OF RECOMMENDED PLAN
AND ALTERNATIVE PLAN
Basic
Technologies
Description
Swirl Concentrator
Swirl Degritter
Chlorine/Chlorine doioxide
Sequential Disinfection
In-line Flow Control
for In-system Storage
BMP Plan (1980)
Management practices
System modifications
In-line storage
Swirl/Disinfection Facilities
at 6 overflow locations
Storage/Sedimentation
Basin
Chlorine
In-line Flow Control for
In-system Storage
In-line storage (1974)
Storage Basins/Disinfection
facilities at 7 overflow
locations
Effectiveness
Capitol Costs
(Million $)
(ENR=4500)
TOTAL
Swirl Degritter at Weiss Complex
(contingency)
56% TSS removal
50% BCD removal
Significant floatables removal
Greater than 90% settleable
solids removal
23.7
52% TSS removal
55% BCD removal
Significant floatables removal
Greater than 90% settleable
solids removal
80.6 (w/Hancock)
70.2 (w/out Hancock)
Operation and
Maintenance
(Annual, 1985
Million)
.49
.76
16
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A. Description of Complete BMP Program
The BMP program concept is to maximize in-line storage
already available in the system conduits and conveyance of storm
flows to the WWTP. To actualize this plan, the existing
regulators were to be modified and new "second tier" in-line
control structures were to be installed to increase in-system
storage.
It was envisioned to alter 24 regulators with vortex
valves to yield a constant discharge during initial storage
filling, with excess flows beyond available storage (for small to
moderate storms) diverted to the interceptor rather than the
river. In addition, the five modified Hancock area regulators
(modified as part of the Hancock Street Detention Facility
Implementation in 1977) were to be replaced with constant
underflow discharge devices (vortex flow valve regulators) to
increase the "first flush" diversion to the interceptor and
maximize the use of the interceptor throughout the storm event.
Furthermore, five other regulators of smaller size were to be
altered with weirs to divert all flows to the interceptor.
Existing weirs at all 34 regulators were to be modified to
enhance in-system storage and to maximize flow to interceptor.
Fourteen upstream structures with vortex valve flow regulators
were to be constructed to yield additional in-line flow control
for storage upstream of the regulator chambers. The resulting
changes to the regulator operations would achieve the maximum
useable in-line storage potential of the system.
An increased weir elevation of five feet was to be
imposed at the Weiss Street Pumping Station to reduce pumped
overflows at that point and increase the flow across the river
crossing and into the East Side Interceptor. This improvement
would maximize West Side "first flush" passage to the WWTP.
B. Description of Swirl Concentrator Complexes
Swirl concentrator facilities were proposed at each of
the six major overflow points. The facilities were to be
tailored to the particular needs of each site. Pumping stations
to drive the swirls were considered necesssary at each site. New
lift stations were to be included for the Weiss Street gravity
overflow and for the Fraser Street overflow. A battery of
various size fixed speed pumps were considered for these
stations. The existing 100-cfs fixed speed pumps were to be used
(after revamping/turning) for all other stations as required.
New low capacity (25-40 cfs) fixed speed pumps were to be
included in all revamped stations to provide variable pumping
range using the revamped fixed speed 100-cfs pumps. The
17
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Fourteenth Street swirl facility was to handle combined gravity
line and pump station discharge ( subject to further hydraulic
and locational studies).
A swirl degritter at the Weiss Street complex may be
necessary if the proposed City-wide system of swirl concentrators
were implemented and pending a careful review of WWTP grit
removal capacity under sustained wet weather high flow
conditions. This degritter contingency was proposed to ensure
that the WWTP's solids handling capacity would not be overtaxed.
Section 3.4 Description of Three Efforts to Develop
the Demonstration Project ^ Phase 1
Three alternative CSO treatment configurations were
investigated in detail so as to provide a suitable demonstration
project. It was anticipated that the 201 program might lend
partial financial support for the project given that a Facility
Plan had been developed and that program elements had been placed
on a priority list for funding. Unfortunately, 201 funding never
materialized and final selection of a demonstration program
occurred in Phase 2.
Alternative 1: Weiss Street Swirl Concentration
Demonstration Project
Although the magnitude of the overflow at Weiss Street
greatly exceeded those at other locations, City-owned land space
to construct the proposed facility (see Figure 8) was extremely
limited. Design of the proposed swirl concentrator facility at
Weiss Street was curtailed due to the envisioned long and
protracted period required to acquire the necessary land.
Estimated construction costs and evaluation equalled $3.1 million
(ENR=4500).
Alternative 2: Proposed Weiss Street Demonstration Project;
Dunker's Floating Tank System
In December, 1980, U.S. EPA introduced Karl Dunkers to
EDP as he was touring the United States marketing a new innova-
tive, extremely cost-effective, flow-storage technology. Karl
Dunkers is an independent Swedish research engineer and inventor
and was commissioned by the National Swedish Board for Technical
Development. In the mid-70's Dunkers experimented with and
obtained an international patent for a pontoon tank system to
equalize inflow in a two fluid media system using plug flow
principles.
18
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CITY PROPERTY LINE
120" Combined
iverslon
Chambe
Regulator
42" INTERCEPTOR
umping
Station
RIVER CROSSING
Swirl
DegHtters
Proposed
Future
: DISIN--:-:
- FECTION----
I- CONTACT.---
-CHAMBERS-.-.
.(FUTURE)-:-!
Figures
>^ PRIVATE ^ *< ^Disinfection chemical
PROPERTY storage building
Layout of Weiss Street combined sewer overflow treatment complex.
-------
During the course of discussions with Dunkers, EDP was
initiating contract work for plans and specifications for the
section 108 swirl technology demonstration project designated for
the Weiss Street area. At that time EDP was informed by the
City of the adverse unresolvable land problem at Weiss Street,
effectively precluding this site from consideration as a swirl
demonstration site. The Dunker's approach minimizes dry land
requirements and its application for the Weiss Street area was
obvious as a means of storing CSO with later bleedback to WWTP.
EDP was immediately directed to investigate this technology as a
potential demonstration project.
In principal, Dunkers1 device creates in a fluid,
through a pontooned celled system, a means of inputting
extraneous fluid (stormwater/CSO) while displacing currently
stored fluid (lakewater) in a plug flow manner. After the storm
event the reverse pattern is created. For a small runoff event,
only one or more of the cells are used and since the device is
finite, it can be overflowed during a large event. The relative
efficiency in transferring flows through plug flow operation is
determined by the number of cells and relative placement.
A conceptual plan view layout of the Dunkers1 pontoon
tank system in the (900 foot long, 100-200 foot wide, 6-10 feet
deep) man-made channel connecting the Weiss Street CSO to the
Saginaw River is depicted in Figure 9. The present channel was
formed in the mid 50's when the interceptor river crossing was
constructed. Low, average high river elevations are 79.0, 81.0
and 84.0 feet, respectively. The channel volume up to elevation
79.0 is estimated to be 0.8 million cubic feet under present
alignment conditions (6).
The project concept would be as follows. CSO
discharging from both the Weiss Street pumping station and the
gravity trunk are to be captured in Dunkers' system subject to
the volumetric limitations of the channel (as improved) during a
given storm event. Discharge (volume) from both the Weiss
gravity/pumped discharge would be automatically monitored and
total volume discharged into the pontoon system noted. Following
the event, the stored overflows would be pumped back into the
interceptor river crossing during suitable dry weather flow
conditions.
Total estimated construction cost including extensive
channel improvements (excluding evaluation) is about $1.6 million
(ENR=4500). It was estimated that the Dunker's storage system
would capture on the average, about 62% of all CSO from Weiss
Street with subsequent bleedback to high-performance WWTP. Over-
all, this approach was more cost effective than the earlier land
based storage /treatment facility programmed for this location
and the swirl concentrator complex proposed in the new facility
20
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SAG IN AW
RIVER
3CHWINK PROPERTY
I 34 ACRES
SCHWINK PROWflTY
904 ACHES
LEGEND
|^^^| PROPOSED ACCESS ROAD
^"^ FENCE (TYP)
|7 — 7~7| ROCK FILL UITH
V / /I RIP RAP FACE
tj Y M AREA T0 BE CUT
IA A Al AND TRIMMED
— POLYETHYLENE FORCE WIN
^ ^V DIRECTION OF FLOW
82.2 EXISTING GRADE (TYP)
® MOTORIZED BALL VALVE
IN METER COX ENCLOSURE
WEISS ST COMBINED
SEWER OVERFLOW FACILITY
DUNKERS TANK SYSTEM
PRELIMINARY
CONTRACT NO SCALE i"= 40'
DRAWN BY PL
CHECKED BY W C P
DATE
4/1/81
DRAWING NO
1 OF 1
EOP Environmental Design & Planning, Inc.
~z=^^^r^Z Engineering. Planning A Field Services
21
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plan. This concept was proposed as a demonstration project but
did not proceed due to the level of available funding.
Alternative 3: Webber Street fiwitl Concentrator
Facility
In raid 1981 it appeared that 201 funding support seemed
probable and EDP was instructed to re-direct efforts for place-
ment of the proposed swirl concentrator facility at an alterna-
tive location within the City. The alternative facility was
nevertheless to be constructed as a logical and congruent
element of the overall adopted CSO Facility Plan. The Webber
Street Pumping Station area was chosen as the new location to
place the proposed demonstration facility. An analysis of this
catchment was conducted supported by detailed field measurement
programs so as to increase the technology scale of the swirl
concentrator (80 cfs) from the scale (50 cfs) proposed in the CSO
Facility Plan (7).
In 1981-1982 EDP prepared construction plans, specifi-
cations and bid documents for a new treatment complex consisting
of an in-line diversion structure controlled by vortex flow
regulation devices to direct flow to the existing pump station,
with lift by a new 80-cfs pumping plant, on to a 38 foot diameter
swirl concentrator. See Figure 10. The cost of the facility was
estimated to be approximately $2.0 million (ENR=4500).
Approximately $.75 million was remaining from the 108
grant and additional 201 funding became unavailable. It was
forcasted that this low status would remain for the next several
years and it was finally decided by U.S. EPA to indefinitely
postpone the proposed demonstration swirl concentrator project.
Section 3.5 Phase 2. 108 Demonstration Project
In early 1983, U.S. EPA and the International Joint
Commission (IJC) ( U.S. and Canada) became interested in
developing phosphorous limitations for the Great Lakes revolving
around a number of promising BMP practices controlling
agricultural and urban runoff phosphorous loadings. Sewerage
system management employing system controls to inexpensively
maximize transient in-line storage with bleedback to WWTP's with
high performance treatment was identified and viewed by U.S. EPA
as a promising management prospect in view of the continuing low
federal funding profile for the next several years. Since a
number of the major sewerage systems impacting the Great Lakes
are combined, relatively flat and discharge to high performance
WWTPs, the notion of evaluating inexpensive system storage and
hydraulic optimization in Saginaw was attractive, feasible and
22
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1_
f-
0>
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logically extendable to other areas within the Great Lakes
region, if proven to work.
On instruction in April, 1983, EDP embarked on Phase 2.
The objective of the Phase 2 evaluation was to determine the
optimum implementation plan for the reduction of CSO impacts to
the Saginaw River based on available money and the elements of
the overall CSO Facility Plan. Optimization included cost
estimation of each plan element followed by a series of model
simulations using various combinations of elements within the
total allotted project budget.
As a first step, additional field evaluations of flow
patterns at various regulator chambers were performed allowing
further calibration of the simulation model. A limited field
investigation was performed including continuous water elevation
recording at several regulators on each side of the Saginaw
River. This data was combined with information routinely
collected by City personnel at the Weiss Street and Hancock
Street Pump Stations and at the WWTP to estimate area wide
hydraulic conditions. Simulations then indicated the optimum
configuration for the "Reduced BMP" implementation plan. This
plan consisted of modifications to the Saginaw sewerage system
only on the West Side of the Saginaw River. See Figure 11 for
locations controlled as part of the "Reduced BMP" plan.
Since the entire BMP plan was not to be implemented at
this time, it was important that all elements of the "Reduced
BMP" plan be designed and implemented such that no modifications
will be required in the future. Furthermore, the concept of the
total BMP plan was to control the system such that overflows
(except for extreme events) would occur only at major pumped
discharge points. Since it was not envisioned to modify the
Emerson Street Pumping Station at this time (for automatic "turn-
on"), the "Reduced BMP" plan was designed such that no additional
capital expenditure for pumpage and/or adverse operational
problems would occur as a result of the implementation. It was
for these reasons that improvements were only programmed for the
West Side.
As part of the "Reduced BMP" plan, 13 of 34, of the
City of Saginaw1s combined sewer regulators were to be modified
in accordance with the CSO Facility Plan Concept. One of the 14
upstream in-system type structures was also to be constructed.
See Figure 12. The Weiss Street Pumping Station weir/wet well
operation was to be modified to increase river crossing discharge
so that more of the West Side "first flush" is transmitted to the
WWTP.
24
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NJ
Ul
r
A
/
r
~i
.V
-Emling Hoococh SI.
Storogt/Trtotnwnt Fodlily
LEGEND
— -— eirr
— .— . UMI
oursioe CITY LIMITS
r
J
• TYPCB
• MODIFIED TYPE B
2p*OSC0MUNEnj0W
OONTMOL/STOMAee OCVCC
4
_J —J
O ELEMENTS COMPLETED
IN 1984
twirl fooKty (i«M d^rtttar)
Wtiti SI (wnping tMiOM
Figure 11 Details of Reduced BMP Plan
-------
CONCRETE FILLETS
TO 108 PIPE
CONFORM
1/4
THEN SLOPE
F0« /4 PIPE DIAMETER
I* PER FOOT
New Vortex Valve Flow
Regulator with Vent
to
CAST-IN-PLACE ANCHM ASSEMLV
SECURE FLOW REGULATOR TO SLA1
CONCRETE FILLETS CONFORM TO 103" PIPE
Figure 12
Salt and Vermont Streets Chamber - Plan View
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Section 3.6 Phase 3. J.Qg pemonstration gr o jecfc
In April, 1983, EDP was instructed to proceed with an
implementation program for the "Reduced BMP" Plan and to prepare
construction plans and specifications. In March 1984, the
construction contract was awarded to Gary D. Steadman, of Bay
City, Michigan. Advanced Fluidics, Inc. supplied the vortex
valves for the project. The construction began in April, 1984
and was completed in September, 1984.
The Phase 1 EDP sewerage system simulation model was
used to estimate City-wide emissions pre/post "Reduced BMP" plan
implementation. Flow measurements using automatic equipment were
made at a number of representative regulators as part of the
Phase 3 preproject conditions. After the "Reduced BMP" plan
project was implemented, flow measurements were conducted to
document the effectiveness of the implemented controls on a
representative basis. A limited post-implementation water quality
sampling program was conducted using automatic sampler
techniques.
Detailed observations were also noted by City
maintenance personnel during routine post storm inspection of
regulator chambers to determine physical conditions. One aspect
of the "reduced BMP" plan was to include low maintenance flow
regulating devices to replace the existing float-operated type.
These existing devices required frequent maintenance and were
subject to failure. The new vortex valve flow regulating devices
performed satisfactorily and have reduced maintenance problems.
Structural changes to regulator chambers were intended
to improve system storage capacities and flow hydraulics without
causing excessive surcharge or in-system sedimentation. Degree
of backwatering was noted at numerous locations upstream in the
sewerage system. Debris accumulations in all regulator areas and
sedimentation in dry weather flow channels were particularly
noted. These observations served to document the reduction in
maintenance labor provided by "Reduced BMP" plan implementation.
The post implementation documentary effectiveness of
the "Reduced BMP" plan improvements in terms of increased wet
weather pollutant loadings to the WWTP was close to pre
implementation predictions. Expenditures of $.504 million (1984
ENR=4500) under the "Reduced BMP" plan for low level sewerage
system modifications (entailing a significant portion of proposed
controls for one-half of the City) resulted in decreasing the
average annual system-wide total phosphorous wet weather loadings
to the river by about 10%. Annual reductions for solids and
organic loadings to the river averaged about 20%. No adverse
conditions resulted from the plan.
27
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Detailed conclusions and specific recommendations
deriving from the Phase 3 program are presented in Appendices A
and Bf respectively.
In sum, the concept of inexpensive system controls to
maximize transient in-line storage of combined sewage with
bleedback to a high performance WWTP worked well and is
recommended as a management practice.
28
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APPENDIX A
108 DEMONSTRATION PROGRAM CONCLUSIONS
EDP has completed a five year 3 Phased study of CSO
pollution from the City of Saginaw, Michigan and concludes that
CSO pollution in Saginaw is controllable at reasonable costs.
Pertinent conclusions associated with the BMP program are
detailed in the following order:
PLANNING £ DESIGN
A. Combined Sewer System Data Reduction Analysis
IMPLEMENTATION £ EVALUATION
B. Implementation of Reduced BMP Plan
C. Evaluation of Implemented Reduced BMP Plan
A. Combined Sewer System Data Reduction Analysis
Wastewater Treatment Plant
(1) The secondary WWTP had the capacity to handle combined
sewage volumes greater than generally flowing to the plant. An
analysis of operating records indicated that both hydraulic and
treatment capacity for additional loadings were available without
impairment of overall WWTP treatment efficiency. Increasing the
flow of combined sewage to the WWTP was a primary goal of this
study. Pollutant loads to the river are expected to be
significantly reduced by increasing flow to the WWTP and storing
excesses within the system until throughput capacity becomes
available.
(2) Review of daily operating records for 1978-1979 indicated
that the BOD removal for the WWTP averages approximately 89% for
both wet days and dry days.
(3) Review of WWTP data indicate wet weather total phosphorous
removal of 50% without AWT. Non-soluble phosphorous removals
are 95% but no soluble phosphorous removal is achieved. The non
soluble fraction averages 54% of the total phosphorous.
(4) Advanced Wastewater Treatment (AWT) (pickling liquor or
PeS04 addition) is used, as required at the WWTP to meet effluent
standards. Phosphorous removals average 75% with AWT and the
29
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entire additional level removed beyond secondary treatment rates
is attributable to a 50% reduction of soluble phosphorous.
Interceptor Sewer Data
(5) The junction of the West Side Interceptor river crossing
and the East Side Interceptor was identified as a hydraulic
bottleneck. The Weiss Street Pumping Station relieves backwater-
/surcharge at the crossing and together with the Weiss Street
gravity overflow constitute the dominant CSO in the system.
(6) The intercepting system's major hydraulic bottleneck is
the river crossing. Application of additional head to the
crossing by raising the weir level at the Weiss Street Pump
station would increase flows across the river. A five foot
weir height increase was estimated to be optimum.
Regulator Data
(7) Regulators (earlier modifed as part of the Hancock Street
Detention Facility improvements (mid 1970's)) had been altered to
cause the underflow orifices to close rapidly, limiting flows to
the interceptor and thus committing the "first flush" of a rain
event to in-line storage created at the chamber. EDP considered
it more advisable to maintain higher underflow discharges to the
interceptor, limited only to what the interceptor can maximally
handle. Operation in this manner will commit the "first flush" of
a rain event, generally carrying the highest concentration of
pollutants, to the interceptor, and eventually to the WWTP.
(8) It appeared during the EDP inspection program that the
mechanical float-operated mechanisms used to regulate flow at
the regulation chambers were slow in responding to rising water
levels. The City reported that the devices required constant
surveillance to maintain operation.
(9) New vortex flow throttling devices having no-moving
parts, large aperture openings (in comparison to conventional
orifices) constructed of durable material (stainless steel) and
reported to be nearly clog-free were envisioned to replace the
existing mechanical float operated mechanisms in the regulators.
In System Storage JJaia
(10) Potential in-line storage capacity in the Saginaw sewer
network is extensive. A total storage volume (including
interceptors and WWTP aeration tanks) of 3.93 million cubic feet
30
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(29.4 million gallons) has been estimated as available without
threatening basement flooding.
B. Implementation of Reduced PMP Plan
(11) Implementation of the "Reduced BMP" plan including
modifications of 12 of 34 combined sewer regulators, construction
of one upstream in-system storage structure and increasing the
effective head at the Weiss Street crossover was completed for
the construction price of $315,000.
(12) Modification of regulator chambers was accomplished
under controlled conditions such that no dry weather sewage or
wet weather combined sewage impacted the river during
construction.
(13) Vortex valve flow regulators were constructed and
installed in variable arrangements to conform to existing
conditions within the regulator chambers. The devices were
segmented for ease of installation particularly where access
space is limited.
C. Evaluation Q£. Implemented BMP Plan
(14) With the exception of limited pollutant removal at the
Hancock Street Facility, all reduction of CSO impact to the
Saginaw River is attributable to increased in-system transient
storage coupled with increased flow to the WWTP. Prior to this
program, it is estimated that on an annual basis, 37.7% of all
wet weather related flow would be handled by the WWTP. For "Low
Rainfall" events (total rain less than 0.5 inches), 53% of the
system wide wet weather flow would be handled by the WWTP.
(15) Implementation of the "Reduced BMP" plan is estimated to
have increased the percentage of total annual wet weather flow
directed to the WWTP by 14.6% (from a previous "as is" level of
37.7%). For "Low Rainfall" events, this incremental increase in
flow directed to the WWTP would be 19%. Implementation of the
remaining elements of the complete BMP plan could produce an
overall incremental increase of 30% (increasing the total wet
weather flow treated at the WWTP to 67.7%). For "Low Rainfall"
events, this incremental increase in flow directed to WWTP would
be 34.6%.
(16) Implementation of the "Reduced BMP" plan is estimated
to have incrementally reduced (beyond "as is" levels) suspended
solids loadings to the Saginaw River by 16%, BOD by 20% and total
phosphorous by 8.5%. During periods of AWT (pickling liquor
addition) at the WWTP, total phosphorous removals will increase
31
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12.6% above pre-implementation levels.
(17) On a weight basis, the "Reduced BMP" plan implementation
is estimated to have reduced wet weather suspended solid
pollutant loads to the river by 1.4 million pounds per year, BOD
by 0.47 million pounds per year and total phosphorous by 3000
pounds per year. Wet weather related total phosphorous loadings
are estimated to be reduced by 3000 to 4000 Ibs. per year
depending on application of AWT.
(18) Incremental TSS and BOD removals of total wet weather
loadings to river attributable to implementation of the complete
BMP program (when completed) are estimated to equal about 29% and
30%, respectively. Total phosphorous reduction with secondary
treatment is estimated to equal 16.7% and with AWT would equal
25% above pre BMP conditions. Mass removals due to implementation
of the complete BMP plan (when completed) are estimated as 2.5
million pounds of SS, 0.68 million pounds of BOD and 7000 to
10,000 pounds of total phosphorous (latter estimate when AWT
used).
(19) WWTP TSS and BOD removal levels noted during the post
construction evaluation period (late 1984) have not diminished,
confirming earlier Phase 1 and Phase 2 projections.
(20) It has been determined that the modification of the
Weiss Street Station spillover weir level has increased the
crossover rate by about 20 cfs under all conditions.
(20) With the exception of a few minor reported incidences of
large stick debris cloggage and grease blockage of device
handling small flows (0.2 cfs), the flow and solids handling
performance of the new vortex valve flow throttling devices
replacing the mechanical float-operated controllers within the
regulation chambers was satisfactory. No adverse flow backup or
sedimentation problems were reported. On one occasion the
devices were visually observed to pass "first flush" and scoured
solids on draindown. Limited flow calibration measurements
indicated that the devices generally operated as per
manufacturer's specifications.
(21) The performance of the new in-line control chamber at
Salt & Vermont Streets which generated at maximum capacity a
transient storage volume of 175,000 cubic feet ($0.57/cubic foot
storage) was satisfactory. The new vortex valve flow throttling
device which controlled the wet weather discharge from this
facility as well as permitting passage of normal dry weather
sewage worked extremely well. No blockages, sediment buildup nor
adverse backups were reported.
32
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APPENDIX B
108 DEMONSTRATION RECOMMENDATIONS
The conclusions stated in Appendix A clearly indicate
the effective use of elements of the BMP plan in reducing CSO to
the Saginaw River. To date, the entire BMP plan has not been
scheduled for completion as the the funding for implementation of
complete facility plan elements is not available. In addition,
the 1984 investigation of the system hydraulics during the
construction and post evaluation phases indicated areas of system
operation where additional review and "fine-tuning" may be
necessary in the future due to hydraulic changes induced by
implemented elements of the BMP plan.
The following recommendations are presented in order of
importance:
1) The "Reduced BMP" plan included modification of only
12 of 34 regulator chambers. All other regulation chambers
should be updated to include new vortex flow regulating devices
as necessary, and appurtenances designed to maximize storage and
minimize bypass to the river.
2) One of 14 proposed upstream in-line storage chambers
was completed. Facilities for the remaining locations should be
designed and constructed. The recommended order of priority for
implementation of these locations is as follows:
In-line Storage Priority List
1. River & Cambrey Streets
2. Birch & Harris Streets
3. Gratiot & Michigan Avenue
4. Cass & Woodbridge Streets
5. Hamilton & Williams Streets
6. Union Avenue & Delaware Street
7. Jackson & Mason Streets
8. MacKinaw Street & Michigan Avenue
9. Troy & Boxwood Streets
10. 17th & Perkins Streets
11. 14th & Norman Streets
12. Hayes Street & Michigan Avenue
13. Weiss & Delaware Streets
The in-line storage facility at Weiss Street and
Delaware Street should be completed as part of the CSO abatement
program work at the Weiss Street Pump Station complex.
33
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3) Existing gate opening and pump "turn-on" sequencing at
the Hancock Street Pump Station should be reviewed to ascertain
whether the operation is optimal. The existing monitoring
equipment at the Hancock Street Pump Station should be
upgraded, if necessary, for the purpose of monitoring station
operation in compliance with optimization recommendations.
4) The pump initialization equipment at the Weiss Street
Pump Station should be reviewed to optimize turn-on/shut-off
elevations and to ascertain whether supplemental operating
controls are necessary due to the weir modification performed as
part of "Reduced BMP" plan.
5) The operations of the Hancock Street Facility and the
Weiss Street Pump Station should be reviewed to ensure that the
Hancock Street Station operates prior to the Weiss Street Station
during a storm event. During areawide storms, detention
storage/treatment currently available at Hancock Street will thus
be utilized prior to untreated bypass at Weiss Street.
6) The CSO control facility for the Weiss Street area
should be implemented as overflows at this location are still the
dominant source of wet weather pollutant load to the Saginaw
River.
7) Under extremely high rate conditions, wet weather flow
pumped to the WWTP grit chamber is split with partial overflow to
the WWTP bypass. Overflow commences at a total rate less than
the existing WWPT flow-through capacity. Possible replacement of
the WWTP overflow bypass weirs with other equipment may allow
initial storm flow containing "first flush" materials to pass to
the aeration basins for storage. Later cleaner flows would be
bypassed, if necessary due to full basin conditions.
8) Currently potential pump cavitation conditions prevent
maintaining WWTP wet well levels at the initial design elevation.
Although the City WWTP personnel maintain maximum wet weather
throughput whenever possible to the WWTP, the elevations
currently maintained, reduce the hydraulic capacity of the
interceptor system during major events causing overflow at
upstream pump stations. Hydraulic conditions of influent pump
intakes at the WWTP wet well should be investigated to determine
if baffles, spoilers or intake vanes could reduce cavitation and
allow lower operating levels, and result in lesser upstream
overflow magnitudes.
34
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REFERENCES
Metcalf & Eddy, Inc., "Report to City of Saginaw, Michigan
on Preliminary Design of the Hancock Street Combined Sewage
Overflow Storage and Treatment Facility," March 16, 1973.
Lager J. et al, Urban Stormwa^ter Management and Technology;
Update and User's Gjiidfir EPA-600/8-77-14. September, 1977.
Pisano, W., Connick, D. and Aronson, G., "Swirl and Helical
Bend Regulator/Concentrator for Storm and Combined Sewer
Overflow Control," October 1984, EDP EPA-600/S2-84-151.
Pisano, Rhodes and Aronson, "Preliminary Engineering Study
for the Control and Treatment of Combined Sewer Overflows to
the Saginaw River", June, 1980, EDP.
Pisano, Rhodes and Aronson, "Facility Plan for the Control
and Treatment of Combined Sewer Overflows to the Saginaw
River", November, 1980, EDP.
Environmental Design & Planning, "Design Development
Document: Weiss Street Combined Sewer Overflow Storage
Facility", March, 1981.
Environmental Design & Planning, Inc., Design and
Development Document Webber Street Combined Sewer Overflow
Treatment Facilities, June, 1981.
35
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
In-System Storage Controls For Reduction
of Combined Sewer Overflow
Saginaw, Michigan
6. REPORT DATE
September 1985
6. PERFORMING ORGANIZATION CODE
5GL
7. AUTHOR(S)
William C. Pisano, P.E., Daniel J.
Connick and Gerald L. Aronson
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
0. PERFORMING ORGANIZATION NAME AND ADDRESS
Department of Public Utilities
City of Saginaw
Saginaw, Michigan
11. CONTRACY/GRANT NO.
ROD5359
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Great Lakes National Program Office
536 South Clark Street, Room 958
Chicago, Illinois 60605
13. TYPE OF REPORT AND PERIOD COVERED
Combined Sewer-1979-1985
14. SPONSORING AGENCY CODE
Great Lakes National Program
Office-USEPA, Region V
IB, SUPPLEMENTARY NOTES
Ralph 6. Christensen
Project Officer
16. ABSTRACT
This report overviews the results of a recently completed five-year combined sewer
overflow (CSO) control program in Saginaw, Michigan (10,000 acres, Pop. 85,000)
funded by City of Saginaw/U.S. EPA 108 Great Lakes National Program. The
implemented control program entailed modification of 13 combined sewer regulation
chamber to maximize transient system storage of wet weather combined sewerage for
later bleedback to a well-operated Wastewater Treatment Plant (WWTP) having
phosphorous removal and ample treatment capacity. These improvements, "the reduced
Best Management Practices (BMP) plan", represent a partial completion of the
first of two phases of the City's CSO Facility Plan. The objective of Phase I
was to maximize WWTP processsing of wet weather combined sewage generated using
inexpensive transient system storage (less than $l/cu.ft.) so as to minimize the
extent, scale and cost of satellite CSO treatment facilities (Phase II). The
swirl concentrator technology was recommended to treat residual overflows remaining
after Phase I improvements. Six major facilities were recommended and adopted as
part of the CSO Facility Plan. In-system storage is controlled with vortex
valve regulators.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
CSO Pollution Suspended solids
Stormwater
Phosphorus loadings
Swirl concentrator
Combined sewer
Total phosphorus
18. DISTRIBUTION STATEMENT
i 5
19. SECURITY CLASS (ThisReport)
21. HO. Of PAGES
to public through the National Information
Service, (NTIS), Springfield, VA 22161
20. SECURITY CLASS (Thispage)
22. PRICE
EPA Form 2220-1 (9-73)
* U.S. GOVERNMKNT PRINTING OFFICE: 1985-557-295/631
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