United States
 Environmental Protection
 Agency
 Municipal Environmental Resean
 Laboratory
 Cincinnati OH 45268
Research and Development
EPA-600/S2-81 -113 July 1981
 Project  Summary
Combined Sewer  Overflow
Abatement  Program,
Rochester,  N.Y.—Volume  I.
Abatement  Analysis
Frank J. Drehwing, Cornelius B. Murphy, Jr., David J. Carleo,  and
Thomas A. Jordan
CSO locations within the Rochester,
New York, Pure Waters District served
as the basis for network  modeling
studies.  The  USEPA  Stormwater
Management Model—Version  II,
Simplified Stormwater  Model, and
receiving water models were used to
evaluate various CSO pollution abate-
ment alternatives.
  Nonstructural,  minimal structural,
and structurally intensive alternatives
were defined and evaluated by these
models. The nonstructural  approach
applied Best Management  Practices
(BMP).  Structural  alternatives in-
volved evaluation  of  conventional
storage and treatment options. Cost
benefit analyses of all structurally
intensive alternatives were conducted
using optimum  treatment process
train configurations developed from
pilot plant evaluations, as reported in
Volume II.*
  Preliminary analysis  of  BMP and
minimal structural alternatives indica-
ted that  by addressing the  major
sources of pollution and by elimina-
ting throttling constraints within the
existing sewerage system, a substan-

"Combmed Sewer Overflow Abatement Program,
 Rochester, N Y Volume II Pilot Plant Evaluations
 F J. Drehwing, C B.'Murphy, Jr., S R. Carver, D F
 Geisser, and D Bhargava EPA-600/2-79-031b
 NTIS Order No PB 80-159 262 (also available from
 the Storm and Combined Sewer Branch, MERL
 USEPA, Edison, NJ 08837)
tial decrease in the total annual load of
contaminants to the receiving waters
from rainfall-induced CSO can be
achieved for relatively small capital
expenditures. These measures can be
initiated within a short period of time,
thereby immediately reducing pollu-
tion to the receiving waters, while
long term design and construction of
more structurally intensive alterna-
tives are undertaken.
  This Project Summary was develop-
ed by EPA's Municipal Environmental
Research Laboratory, Cincinnati, OH,
to announce key  findings  of the
research project that is fully docu-
mented in  a separate report of the
same title (see Project Report ordering
information at back).

Introduction
  In response to the transient water
quality problems induced by periodic
overflows from the Rochester Pure
Waters   District's   combined  sewer
system,  a project was undertaken to
develop  an  abatement and manage-
ment program necessary to achieve a
cost effective solution to  the CSO
induced impairment of the Genesee
River,  Irondequoit  Bay,  and Lake
Ontario.
  Other aims of the project were to
demonstrate the usefulness of mathe-
matical models (the  Simplified Storm-

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water  Model  (SSM)  developed  by
Metcalf & Eddy, Inc., and the USEPA
Stormwater   Management   Model—
Version II (SWMM)) simulating both the
urban  rainfall/runoff process and the
subsequent stormwater flows within a
large combined sewer system; present
the  merits of implementing the BMP
program  to abate  CSO; and evaluate
source and collection system manage-
ment options.
  The developed management program
(including the methodology of approach,
urban stormwater mathematical model-
ing, and abatement alternative analysis
that  involved  both  structural and BMP
measures) lead to the formulation of a
master plan  for CSO pollution  abate-
ment within the Rochester Pure Waters
District.
Problem Definition
  All  programs adopted  by Monroe
County for the  Rochester Pure Waters
District  are directed at meeting state
and  federal  water quality  standards
established for the Rochester, NY, area.
These programs specifically address the
problem  of  receiving  water  quality
degradation due to urban storm runoff
and subsequent CSO.  The study area
including  the  major  receiving water
bodies, intercepting sewer network, and
significant overflow  relief points are
shown in Figure 1.
  Present  CSO directly  contravenes
established water quality standards for
the  Genesee  River,  imposes  heavy
nutrient  and  chemical  loadings  on
Irondequoit  Bay, and causes bacterial
contamination  of  the  public bathing
beaches along  the Rochester Embay-
rrient  of Lake Ontario. The  latter has
resulted in periodic beach closing days
during the summer months.
  Aside from such direct impacts as ob-
jectionable floating material and high
bacteria loadings, the settling of oxygen
demanding materials discharged during
overflow events contribute to  contra-
vening stream standards in  the lower
reaches of the Genesee River under dry-
weather conditions.
  Previous  studies of  the District's
combined  sewer system  cited  major
deficiencies  in  the  existing   sewer
system and identified the effects of CSO
on the area receiving waters.

Project Elements
  The project was divided into three
basic  elements: a CSO  monitoring and
assessment program,  a  CSO mathe-
matical modeling program, and a pilot
plant  demonstration  program.  The
monitoring and modeling programs are
described in detail in Volume I (summar-
ized here) and the pilot plant studies, in
Volume II.
  As  part of the overflow monitoring
program, an intensive CSO flow record-
ing and  sampling  system was  imple-
mented  to  define   the  frequency,
volume,  and pollutant characteristics
associated with the District's CSO dis-
charges.  A  drainage  basin  field
investigation was conducted to define
those basin parameters that affect the
urban stormwater runoff process.
  These  two  programs  provided the
necessary data  sets,  including repre-
sentative CSO hydrographsandpolluto-
graphs, drainage basin characteristics,
and  sewer  system inventory, to facili-
tate  model  calibration and verification.
Included in the modeling effort was the
refinement  and  verification  of the
previously  developed  Genesee  River
Water Quality Model.
  The pilot  plant  program  involved
designing and constructing a pump sta-
tion  and pilot treatment facilities  to
evaluate the effectiveness of eight unit
processes:  high-rate flocculation/sedi-
mentation, swirl  degrittmg,  swirl
primary  separation,  high-rate  dual-
media  filtration,  granular  activated
carbon adsorption,  high-rate disinfec-
tion  using chlorine, high-rate disinfec-
tion  using chlorine dioxide, and micro-
screening. These results  were used to
develop process models and associated
cost effectiveness relationships.
Conclusions

  1.  A rigorous defining of the existing
     system  of CSO  and stormwater
     facilities is fundamental for devel-
     oping an abatement program. This
     definition   includes  identifying
     major  drainage  basins,  major
     trunk and  intercepting sewers,
     and  CSO  and stormwater relief
     points.

  2.  Installing and properly maintain-
     ing overflow monitoring instru-
     mentation are essential for both
     receiving  water problem  defini-
     tion  and any subsequent sewer
     network and  water quality model
     calibration and verification.
 3.  Collecting accurate rainfall data
     and   subsequent  statistical
     analyses,  including defining the
     design storm, are  essential in
     evaluating  the  response of the
     existing system as well as the ef-
     fectiveness of various abatement
     alternatives.

 4.  Developing  a  methodology  of
     approach and defining applicable
     abatement alternatives early in
     the program will ensure that the
     purpose of the study is not lost and
     all data collection activities are
     conducted   according  to  the
     required analyses.

 5.  SSM  is capable  of  providing a
     preliminary screening of potential
     abatement alternatives involving
     a balance between storage and
     treatment.

 6.  SWMM can  project  the  urban
     storm runoff andquantitieswithin
     acceptable confidence limits but is
     presently limited  in its ability to
     simulate overflow quality.

 7.  Overflow quality  can be  better t
     simulated  by applying statistical *
     techniques using  actual  moni-
     tored overflow data.

 8.  The ability to abate CSO pollution
     may   require  implementing
     structurally-intensive facilities. In
     Rochester, one structural alterna-
     tive involves grit removal, in con-
     junction   with   the  optimized
     operation  of the F.  E. Van Lare
     Treatment Facility.

 9.  In  many situations, significantly
     reducing the total annual load of
     contaminants  discharged  to
     receiving waters because of CSO
     can be reduced through minimal
     structural  improvements to the
     existing   sewer  system.  In
     Rochester,  minimal  structural
     abatement  alternatives include
     removing  three  throttling  con-
     straints, modifying  or  adjusting
     overflow  weirs  and regulators,
     and  using inflatable dams  for
     increased  in-system storage.

10.  Implementing   nonstructural
     abatement alternatives (BMP)can
     reduce the annual load of  pollu-
     tants  discharged by CSO and  A
     stormwater. Implementing inflow fl

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     restriction regulations(e.g., use of
     porous pavement) in select areas
     and more intensive street clean-
     ing and sewer  maintenance can
     alleviate a portion of CSO induced
     water quality degradation.

11.  Based  on  projections  using a
     simplified  mathematical storm-
     water  model, the  nonstructural
     and minimal structural abatement
     alternatives  are  expected   to
     reduce significantly  the existing
     volume of  CSO and  the average
     annual BODsand TSS loadings to
     the Genesee  River.


Recommendations
  It is recommended that:

  1.  Network models, such asSWMM,
     be relied on, mostly, for determin-
     ing runoff and overflow volumes
     for selected storm events and less
     for estimating the  quality of the
     runoff. Use statistical analyses of
     actual  field  monitored data  to
     estimate surface runoff quality.

  2.  Initial  screening, planning,  and
     designing  of  storage  and
     treatment abatement alternatives
     be  made  with  a  simplified
     continuous simulation  model  to
     avoid  the  prohibitive  computer
     costs  associated with many de-
     tailed hydraulic models. Use only
     a model that  will satisfy the ob-
     jectives of a  study at the  least
     possible cost.

  3.  Hydraulic analysis and design of
     sewer systems be conducted with
     a detailed network model such as
     SWMM.

  4.  Rainfall   characterization   be
     based,  primarily, on the use  of
     historical  precipitation  data,
     although the design storm  ap-
     proach may have to be applied in
     certain situations. More research
     should be conducted on the con-
     cept of design storms to establish
     design  rainfall hyetographs that
     could  be  applied  with mathe-
     matical network runoff models.

  5.  Models not be  used to predict
     runoff/overflow  quantities   or
     qualities without proper field cali-
     bration and verification. A  rela-
     tively  detailed  field monitoring
     program  is essential in providing
     the background data for proper
     model calibration and verification.

  6.  More statistical analyses be con-
     ducted to  better  establish the
     correlation between runoff quality
     and  parameters such as rainfall
     and land use characteristics.
 7.  Detailed  hydraulic  analyses  be
     conducted to better define inter-
     ceptor throttling constraints,
     regulator/weir modifications, and
     control  structure  locations.
     SWMM is capable of providing the
     required analyses.

 8.  BMP be considered when conduc-
     ting any CSO abatement program.
     In  many instances implementing
     BMP, possibly in conjunction with
     minimal-structural  alternatives,
     can  alleviate  many  problems
     associated  with  frequent  CSO
     discharges. Failure to investigate
     their effects could severely limit
     establishing cost effective abate-
     ment solutions.

 9.  A program be initiated to  investi-
     gate the  effectiveness  of  in-
     creased  street  sweeping  on
     reducing the pollutant loadings to
     the  sewer  system.  Include
     provisions  for  correlating  the
     effects of increased street  sweep-
     ing operations, types of equip-
     ment used, street parking use and
     restrictions, and program costs for
     reducing surface pollutants avail-
     able  for  washoff during  storm
     events.

10.  A master plan for CSO pollution
     abatement   be  developed  and
     implemented  that   follows   a
     sequence of phasing of required
     system  improvements according
     to  their projected cost  effective-
     ness.

11.  Scheduled reviews be included in
     any CSO  abatement  program to
     periodically  evaluate the  effec-
     tiveness and cost/benefits asso-
     ciated  with  alternative  imple-
     mentation. This periodic  review
     will  ensure  that   previously
     defined objectives are being met
     and,  if  not,  changes  to  the
     program can be made  to better
     solve the initial  problems.
  The full report was submitted in ful-
fillment  of  Grant  No.  Y-005141  by
O'Brien & Gere Engineers, Inc., under
the partial  sponsorship of the U.S.
Environmental Protection Agency.
                                                                                       6 U&QCNEftNMEHtmKnNaOFFICE W1 .T57-OU/7239

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       Frank J. Drehwing, Cornelius B. Murphy, Jr., David J. Carleo, and Thomas A.
         Jordan are with O'Brien & Gere Engineers, Inc., Syracuse, NY 13201.
       Richard Field, Anthony Tafuri, and Lawrence Moriarty (retired) are the EPA
         Project Officers (see below).
       The EPA  Grant Officer is Ralph G. Christensen (see below).
       The complete report, entitled "Combined Sewer Overflow Abatement Program,
         Rochester. N.Y.: Volume I. Abatement Analysis," (Order No. PB 81'-219 602;
         Cost: $15.50, subject to change) will be available only from:
               National Technical Information Service
               5285 Port Royal Road
               Springfield. VA 22161
               Telephone: 703-487-4650
       The EPA  Project Officers can be contacted at:
               Storm and Combined Sewer Section
               Municipal Environmental Research Laboratory-Cincinnati
               U.S. Environmental Protection Agency
               Edison, NJ 08827
       The EPA  Grant Officer can be contacted at:
               Great Lakes National Program Office
               USEPA. Region V
               Chicago, IL 60604
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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