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WATER POLLUTION CONTROL RESEARCH SERIES
11024FKN11/69
  Stream Pollution And Abatement
  From Combined Sewer Overflows
  BUCYRUS, OHIO
U.S. DEPARTMENT OF THE INTERIOR • FEDERAL WATER QUALITY ADMINISTRATION

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              WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Reports describe the results and
progress in the control and abatement of pollution of our Nation's
waters.  T^ey provide a central source of information on +>ie research,
development and demonstration activities of the Federal Water Quality
Administration, Department of the Interior, through in-house research
and grants and contracts with Federal, State, and local agencies,
research institutions, and industrial organizations.

Triplicate tear-out abstract cards are placed inside the back cover to
facilitate information retrieval.  Space is provided on the card for
the user's accession number and for additional keywords.

Inquiries pertaining to Water Pollution Control Research Reports should
be directed to the Head, Project Reports System, Room 1103, Planning
and Resources Office, Office of Research and Development, Department
of the Interior, Federal Water Quality Administration, Washington, D.C.
202U2.

Previously issued reports on the Storm and Combined Sewer Pollution
Control Proaram:

      WP-20-11  Problems of Combined  Sewer Facilities and Overflows -
                1967.
      ¥P-£0-15  Water Pollution Aspects of Urban Runoff.
      ¥P-20-16  Strainer/Filter Treatment of Combined Sever Overflows.
      wP-^O-17  Dissolved Air FloTatron MT*eatment of Commned .^fiwer
                Overflows.
      WP-'>0-l8  Improved Sealants for Infiltration Control.
      WP-20-21  Selected Urban Storm WaLej.- Runoff Abstracts.
      WP-20-22  Polymers for Sewer Flow Control.
      ORD-lf     Combined Sewer Separation Using Pressure Sewers.
      DAST-U    Crazed Resin Filtration of Combined Sewer Overflows.
      DAST-5    Rotary Vibratory Fine Screening of Combined Sewer
                Overflows.
      DAST-6    Storm Water Problems  and Control in Sanitary Sewers,
                Oakland and Berkeley, California.
      DAST-9    Sewer Infiltration Reduction by Zone Pumping.
      DAST-13   Design of a Combined  Sewer Fluidic Regulator.
      DAST-25   Rapid-Flow Filter for Sewer Overflows.
      DAST-29   Control of Pollution  by Underwater Storage.
      DAST-32   Stream Pollution and  Abatement from Combined Sewer
                Overflows - Bucyrus,  Ohio.
      DAST-36   Storm and Combined Sewer Demonstration Projects  -
                January 1970.
      DAST-37   Combined Sewer Overflow Seminar Papers.

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STREAM POLLUTION AND  ABATEMENT  FROM COMBINED  SEWER  OVERFLOWS

                             BUCYRUS, OHIO
                       A  Study of Stream Pollution
                    From  Combined Sewer Overflows and
                    Feasibility of Alternate Plans for
                   Pollution Abatement  in Bucyrus, Ohio
           FEDERAL WATER  QUALITY ADMINISTRATION
                      DEPARTMENT OF THE  INTERIOR
                                   by
                       Burgess and  Niple,  Limited
                          Consulting Engineers
                         2015 West  Fifth Avenue
                          Columbus,  Ohio 43212
                         Contract  No.  14-12-401
                               I 1024 FKN
                             November,  1969
           For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $2.

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           FWPCA Review Notice
This report has been reviewed by the Federal
Water Pollution Control Administration and
approved for publication.  Approval does not
signify that the contents necessarily reflect
the views and policies of the Federal Water
Pollution Control Administration.
                       i i

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                              ABSTRACT
This report contains the results of a detailed engineering investigation
and comprehensive technical study to evaluate the pollutional effects
from combined sewer overflows on the Sandusky River at Bucyrus, Ohio and
to evaluate the benefits, economics and feasibility of alternate plans
for pollution abatement from the combined sewer overflows.  The City of
Bucyrus is located near the upper end of the Sandusky River Basin which
is tributary to Lake Erie.  Bucyrus has an incorporated area of about
2,340 acres, a population of 13,000, and a combined sewer system with an
average dry weather wastewater flow of 2.2 million gallons per day.  A
year long detailed sampling and laboratory analysis program was con-
ducted on the combined sewer overflows in which the overflows were
measured and sampled at 3  locations comprising 64$ of the City's sewered
area and the river flow was measured and sampled above and below
Bucyrus.

The results of the study show that any 20 minute rainfall greater than
0.05 of an Inch will produce an overflow.  The combined sewers will over-
flow about 73 times each year discharging an estimated annual volume of
350 million gallons containing 350,000 pounds of BOD and  1,400,000
pounds of suspended solids.  The combined sewer overflows had an average
BOD of  120 mg/l,  suspended solids of 470 mg/l, total col I forms of
 11,000,000 per  100 ml and  fecal col I forms of  1,600,000 per  100 ml.  The
BOD concentration of the  Sandusky River,  immediately downstream from
Bucyrus, varied from an average of  6 mg/l during dry weather to a high
of 51 mg/l during overflow discharges.  The suspended solids varied from
an average of 49  mg/l during dry weather to a high of 960 mg/l during
overflow discharges.  The  total coliforms varied from an  average of
400,000 per  100 ml during  dry weather to a high of 8,800,000 per  100 ml
during  overflow discharges.

Various methods of controlling the  pollution  from combined sewer over-
flows are presented along  with their degree of protection, advantages,
disadvantages and estimates of cost.  The methods presented  include
(I) complete separation,  (2) interceptor sewer and  lagoon system,
(3) stream flow augmentation, (4) primary treatment, (5)  chlorination,
and (6) offstream treatment.  It was concluded that the most economical
method of providing a high degree of protection to the Sandusky River  is
by collecting the combined sewer overflows with a  large  interceptor and
using an aerated  lagoon system to treat the waste  loads  from the over-
fIows.

This report was submitted  In fulfillment of Contract  14-12-401 between
the Federal Water Pollution Control Administration and Burgess & Niple,
 Limited.
                                  ii

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                             CONTENTS

Section                                                            Page

    I.   Conclusions and Recommendations                              I
   I I.   Introduction                                                 7
  III.   Purpose and Scope                                            9
   IV.   Study Area                                                  I I
    V.   Procedures                                                  13
   VI.   Dry Weather Conditions                                      17
             Collection System                                      17
             Interceptor System                                     17
             Wastewater Treatment Plant                             17
             Sandusky River                                         18
  VII.   Wet Weather Conditions                                      19
             Col lection System                                      19
             Interceptor System                                     I 9
             Wastewater Treatment Plant                             20
             Sandusky River                                         20
 VIII.  Meteorological and Hydro logical History                     21
             Meteorological History                                 21
             Hydrological History                                   21
   IX.   Weather Conditions During Study Period                      25
             Rainfal I  Data                                          25
             Sandusky River Flow                                    25
    X.   Drainage Characteristics of the Sewer Districts             29
             History                                                29
             General Description                                    29
             Detailed Description                                   30

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Section                                                            Pa9e

   XI.  Hydraulic Analysis of the Sewer and Interceptor
        Systems                                                     35
             Sewer Systems                                          35
             Interceptor System                                     36
  XII.  Analysis of Rainfall and Overflow Data                      41
             Tabulation of Hydraulic Data                           41
             Rainfall versus Overflow Graphs                        41
             Analysis of Rainfall Data                              42
 XIII.  Wastewater Characteristics of Combined Sewer
        Overflows and Receiving Stream                              47
             Dry Weather Samp I Ing                                   47
             Overflow Samples                                       48
             Sandusky River  Samples                                 49
  XIV.  Aquatic Biology Survey of the  Sandusky River                69
    XV.  Relationship of Rainfall and Runoff                         75
             Start of Overflow                                      75
             Hydrograph Shape                                      76
             Hydrograph Peak and Volume                             77
                   (I)  Rational Formula                             78
                   (2)  Hydrograph Method                            83
                   (3)  Modified Hydrograph Method                   83
  XVI.  River  Response to  Rainfall                                  89
             Urban Runoff  Hydrograph                                89
             Upstream Drainage  Basin Runoff Hydrograph             89
  XVII.  Evaluation and Correlation of  Waste Load  Data               91
             Waste Loads  versus  Overflows                           91
             Waste Loads  versus  Rainfall                            9'
             Effect  of Overflows on  River  Water Quality            92
                                  VI

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Section                                                            Page

XVIII.  General Design Conditions                                   95
             Design Storms                                          96
             Peak Rate of Overflow                                  97
             Volume of Overflow                                     98
             Design Waste Loads                                     98
  XIX.  Alternate Solutions                                        105
             A.  Complete Separation of Sanitary
                 Wastewater and Storm Sewer                        105
                 (I)  Advantages of Separate Sewer Systems         105
                 (2)  Disadvantages of Separate Sewer
                      Systems                                      105
                 (3)  Cost of Sewer Separation                     106
             B.  Interceptor Sewer and Lagoon System               107
                 (I)  Gravity  Interceptor System                   107
                 (2)   Interceptor Sewer Using Holding
                      Tanks                                        107
                 (3)  Pump Station                                 108
                 (4)  Aerated  Lagoon                               108
             C.  Stream Flow Augmentation                          112
             D.  Primary Treatment of Overflows                     113
             E.  Chlorination of Overflows                         114
             F.  Off-Stream Treatment                               114
    XX.   Procedure  for Evaluating Similar Systems  in
         Other  Communities                                          I'7
             Analyze  Existing  Sewer System                          118
             Select Design Storm and Return  Frequencies             118
             Determine  the Runoff From Design Storms                119
             Determine  Waste Loads From Design  Storms               120
             Method of  Collection and Treatment                     120
   XXI.   Acknowledgments                                            123
  XXII.   References                                                 '25
 XXIII.   Figures                                                     129
                                VI I

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                              TABLES


Table                                                              Page


    I       Average Monthly Rainfall  at Bucyrus, Ohio                23

    2      Percent of Time Indicated Sandusky River Flow at
              Bucyrus is Equaled or Exceeded                        24

    3      Rainfall During Study Period                             26

    4      Sandusky River Flow During Study Period                  27

    5      General Drainage Characteristics of Selected
              Sewer Districts                                       32

    6      Land Use and Land Cover of Selected Sewer Districts      33

    7      Drainage Areas and Classifications                       34

    8      Maximum Sewer System Capacities and Times of
              Concentration                                         38

    9      Maximum Overflow Rates                                   39

    10      Rainfall and Overflow Data - Number 8 Sewer District     43

    II      Rainfall and Overflow Data - Number 17 Sewer District    44

    12      Rainfall and Overflow Data - Number 23 Sewer District    45

    13      Data Summary                                             51

    14      Summary of Dry Weather Waste Loads                       52

    15      Summary of Laboratory Analyses On Overflow Samples       57

    16      Summary of Waste Loads for Each Overflow Event           60

    17      Summary of Wet and Dry Weather River Analyses            63

    18      Summary of Aquatic Biology Survey of the Sandusky
              River                                                 70

    19      Time to Start of Overflow                                75

    20      Rainfall to Cause Overflow                               76

    21      Runoff Coefficients                                      79
                                  IX

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Table                                                              Page


  22      Weighted Runoff Coefficients                              79

  23      Comparison of the Rational Formula to Measured Data       81

  24      Overflow Peaks Using Rational Formula for the
             Two-year Storm                                         82

  25      Overflow Volume Using Standard Infiltration Curve         84

  26      Probability of the Design Storms                          99

  27      Overflow Peaks and Volume for the Two-year,
             One-hour Storm                                        100

  28      Overflow Volumes for the One-year, 24-hour Storm         101

  29      Design Storms and Waste Loads                            103

  30      Summary of Cost Estimates for Alternate Solutions        116

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                               FIGURES


Figure                                                             Page


   I       Sandusky River Drainage Area                             131

   2      General  Plan of Combined Sewer Districts                 132

   3      Number 8 Sewer District                                  133

   4      Number 17 Sewer District                                 134

   5      Number 23 Sewer District                                 135

   6      Upstream Sampler and  Number 23 Rain  Gage                 136

   7      Number 17 Weir During Overflow and Number 8
             Dry Weather Weir                                      137

   8      Numbers 8 and 17 Overflow Weirs                          138

   9      Number 8 Instrument Shelter and Wastewater
             Treatment Plant Overflow Recorder                     139

  10      Upstream and Downstream Gages                            140

  II      Low Flow Conditions                                      141

  12      Sandusky River Flow at Bucyrus, Ohio                     142

  13      Comparison of Monthly Discharge and
             Monthly RainfalI                                      143

  14      Rainfall Depth - Duration - Frequency Curves             144

  15      Intensity - Duration Curves                              145

  16      Rainfall and Overflow - Number 8 Overflow -
             March 24, 1969                                        146

  17      Rainfall and Overflow - Number 17 Overflow -
             March 24, 1969                                        147

  18      Rainfall and Overflow - Number 23 Overflow -
             March 24, 1969                                        148

  19      Rainfall and Overflow - Number 8 Overflow -
             June 13, 1969                                         149
                                  XI

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Figure


  20     Rainfall  and Overflow - Number 17 Overflow -
            June 13,  1969                                          150

  21     Rainfall  and Overflow - Number 23 Overflow -
            June 13,  1969                                          151

  22     Intensity -  Duration Curves - Rainfall
            Corresponding to Measured Overflows                     152

  23     BOD Concentration versus Time - Number  8 Overflow         153

  24     BOD Concentration versus Time - Number  17 Overflow        154

  25     BOD Concentration versus Time - Number  23 Overflow        155

  26     Suspended Solids Concentration versus Time -
            Number 8 Overflow                                      156

  27     Suspended Solids Concentration versus Time -
            Number 17 Overflow                                     157

  28     Suspended Solids Concentration versus Time -
            Number 23 Overflow                                     158

  29     Total  Solids -  Number  8 Overflow                          159

  30     Total  Solids -  Number  17 Overflow                         160

  31     Total  Solids -  Number  23 Overflow                         161

  32     Nitrate Nitrogen - Number 8 Overflow                      162

  33     Nitrate Nitrogen - Number  17 Overflow                     163

  34     Nitrate Nitrogen - Number 23 Overflow                     164

  35     Ammonia and Organic Nitrogen - Number 8 Overflow          165

  36     Ammonia and Organic Nitrogen - Number 17 Overflow         166

  37     Ammonia and Organic Nitrogen - Number 23 Overflow         167

  38     Total  Phosphates - Number 8 Overflow                      168

  39     Total  Phosphates - Number  17 Overflow                     169

  40     Total  Phosphates - Number  23 Overflow                     170
                                  XI I

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Figure                                                             Page


  41       Chlorides - Number 8 Overflow                            171

  42      Chlorides - Number 17 Overflow                           172

  43      Chlorides - Number 23 Overflow                           173

  44      Effect of Settling on BOD and Suspended Solids           174

  45      Diurnal Fluctuation in Dissolved Oxygen -
             Sandusky River                                        175

  46      Diurnal Effect on Dissolved Oxygen -
             Sandusky River                                        176

  47      Dissolved Oxygen Profile of the Sandusky River
             During Dry and Wet Weather                            177

  48      Overflow Peak Time versus Length of Rainfall             178

  49      Unit Hydrograph - Number 8 Overflow                      179

  50      Unit Hydrograph - Number  17 Overflow                     180

  51      Unit Hydrograph - Number  23 Overflow                     181

  52      Peak Rainfall versus  Peak Overflow Rate -
             Number  8 Overflow                                     182

  53      Peak Rainfall versus  Peak Overflow Rate -
             Number  17 Overflow                                   183

  54      Peak Rainfall versus  Peak Overflow Rate -
             Number  23 Overflow                                   184

  55      Overflow Hydrograph - 20-Minute Storm  -
             Number  8 Overflow                                     185

  56      Overflow Hydrograph - 20-Minute Storm  -
             Number  17 Overflow                                   186

  57      Overflow Hydrograph - 20-Minute Storm  -
             Number  23 Overflow                                   187

  58      Rainfal I versus  BOD                                      188

  59      Rainfall versus  Suspended Solids                         189
                                 XIII

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Figure


  60      Rainfall and Overflow - Two-year, One-hour Storm -
             Number 8 Overflow                                     190

  61      Rainfall and Overflow - Two-year, One-hour Storm -
             Number 17 Overflow                                    191

  62      Rainfall and Overflow - Two-year, One-hour Storm -
             Number 23 Overflow                                    192

  63      Distribution Graph for Urban Runoff -
             Downstream Gage                                       193

  64      Separation of Sanitary and Storm Sewer -
             Typical Cross Section                                 194

  65      Interceptor and Lagoon System                            195

  66      Typical Cross Section of Aerated Lagoon                  196

  67      Flow Augmentation Upground Storage  Reservoir             197
                                   XIV

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                              SECTION I

                   CONCLUSIONS AND RECOMMENDATIONS
Conclusions

 I.  Any 20 minute rainfall  greater than 0.05 inches will produce an
     overflow of wastewater into the Sandusky River at Bucyrus.  A rain-
     fall of this intensity and duration or greater will occur on the
     average of once every 5 days.

 2.  A typical summer thundershower occurred on June  13, 1969 and pro-
     duced  I.I Inches of rain, had a duration of 78 minutes and an
     average  Intensity of 0.84 inches per hour.  The  runoff from this
     storm discharged into the Sandusky River, through the combined
     sewer overflows, 5,200,000 gallons of combined sewer wastewater,
     1580 pounds of BOD and 23,000 pounds of suspended solids.

 3.  A  storm  on August 9,  1969 which produced 0.50  Inches of  rain  in
     about  75 minutes,  increased  the BOD concentration of the  Sandusky
     River  downstream from  Bucyrus from  II mg/l  (530  pounds per day) at
     a  river  flow  of 9  cfs  to 51  mg/l  (35,500 pounds  per day)  at a  river
     flow  of  130  cfs.

 4.  The combined  sewers  will overflow about 73  times each year dis-
     charging an  estimated total  annual  volume of  350 million gallons
     or about I  million gallons per day.

  5  The combined sewer overflows have an average  BOD of 120  mg/l,  sus-
      pended solids of  470 mg/l, total  col I forms  of 11,000,000 per  100  ml
      and fecal coliforms of  1,600,000 per 100 ml.

  6.   The combined sewer overflows at Bucyrus discharge  an estimated
      350,000 pounds of  BOD and 1,400,000 pounds of suspended  solids
      annually Into the Sandusky River.

  7.   The BOD concentration of the Sandusky River,   immediately downstream
      from Bucyrus, varied from an average of 6 mg/l during dry weather
      to a high of 51 mg/l during overflow discharges.  The suspended
      solids varied from an average of 49 mg/l during dry weather to a
      high of 960 mg/l  during overflow discharges.   The total  coliforms
      (by membrane filter technique) varied  from an average of 400,000
      per 100 ml during dry weather to a high of 8,800,000 per 100 ml
      during overflow discharges.

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8.  The estimated yearly discharge of  15,700  pounds of nitrate nitrogen
     (12,200  pounds  from overflows and  3,500 pounds from wastewater
     plant)  from  Bucyrus  is  rather  insignificant when compared to the
     136,000  pounds  and  192,000  pounds  found  in the river coming from
     the upper  drainage basin  on April  19,  1969 and May  19,  1969,
     respectively.

9.   The nitrate  nitrogen concentration of  the Sandusky River, upstream
     from  Bucyrus, varied from a low  of 0.4 mg/l as NO^ to  a  high of
     32 mg/1.   The high concentrations  occurred during high  river flows
     in the  spring of  the year.  The  estimated nitrate nitrogen dis-
     charged  from the  upstream drainage area  is 2,300,000 pounds
     annually.

10.   The combined sewer overflows  discharge about  30,000  pounds of  phos-
     phates  (PO.) into the  river annually.  The wastewater  treatment
     plant discharges  about 160,000 pounds  of  P04  each year.   An
     estimated  110,000 pounds  of PO.  per year  came from  the upstream
     drainage area.

II.   Sludge  accumulation  in the  river from combined  sewer overflows at
     Bucyrus is estimated to be  approximately 47,000 cubic  feet  per year.

12.   The flushing effect of the  sewer system during intense rainfalls
     causes the majority of the waste  load to be discharged during  the
     peak overflow period as evidenced by the peak concentration of the
     various water quality characteristics which tend to coincide with
     the peak overflow rate.

13.   The effects of the combined sewer overflows on the  Sandusky River
     in and below the Cfty of Bucyrus are visually apparent.  There are
     Indications of gross pollution,  such as sludge banks,  sections of
     the river are devoid of oxygen,  extensive algae growth, and some
     sections of the river are completely devoid  of life.

14.   The probability of  thundershower type storms occurring Is highest
     during the summer months.  There  is a 74^ probability of the 2 year,
     I  hour thundershower,  which has a total   rainfall of 1.23 inches,
     occurring In June,  July and August.

15.   The median flow In the Sandusky River at Bucyrus in June, July and
     August  Is 13 cfs, 6.9 cfs  and 4.8 cfs, respectively.

16.  The assimilative capacity  of the  Sandusky River (the ability of the
     river for self-purification) is limited  to approximately 25 pounds
     of BOD  per day per cfs at  flows less than 10 cfs.  Forty percent of
     the time  the flow In the Sandusky River  at Bucyrus Is  less than
     10 cfs.

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17.   The  weighted  average  runoff  for  a I I  storms  measured  was  19  percent.
     For  storms with  over  1.0  inches  of  rainfall,  the  weighted average
     runoff  through the  combined  sewers  equals 20  percent,  28  percent
     and  25  percent for  Sewer  Districts  8,  17 and  23,  respectively.

18.   The  volume and character  of  pollutants discharged to surface  water-
     courses from  combined sewer  systems in other  similar communities
     would no doubt be very similar to  that found  to exist at  Bucyrus,
     Ohio.

19.   The  various methods of reducing  or controlling pollution  from com-
     bined sewers  considered in this  study  and the estimated  project
     cost of each  are as follows:

     A.   Complete  separation of the combined sewer system into a sanitary
         sewer system and  storm sewer system.

          I.   Construct new sanitary sewers  using the existing  system
             as storm sewer system — $9,300,000.

         2.   Construct new storm  sewer system using existing  system as
             sanitary sewer system — $8,800,000.

     B.    Interceptor Sewer and Lagoon System

          I.   Gravity  Interceptor                   $3,600,000

          2.   Pump Station                           1,000,000

          3.   Lagoon System                            620.000

                                                   $5,220,000

     C.   Stream Flow Augmentation                  $5,000,000

     D.   Primary Treatment of Overflows            $8,810,000

     E.   ChiorI nation of  Overflows                 $3,000,000

     F.   Offstream Treatment

          I.   Pump Station and
             Low Head Dam                         $1,080,000

          2.   Lagoon  System                           620,000

                                                   $1,700,000

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20.  Sewer separation, at Bucyrus, as a solution to combined sewer over-
     flows will only reduce the waste loads discharged to the river by
     about 50%.

21.  Construction and operation of the "Interceptor and Lagoon System"
     or "Off-Stream Treatment" as a demonstration project would be the
     most economical method of reducing or controlling pollution of the
     Sandusky River at Bucyrus and would provide answers to certain
     design, operation and benefit unknowns.

22.  Stream flow augmentation as a method of controlling pollution from
     combined sewer overflows is not feasible at Bucyrus due to lack of
     suitable reservoir sites.

23.  Primary treatment of overflows will only reduce the waste loads
     discharged into the Sandusky River through the combined sewer over-
     flows by 50 to 70 percent.

24.  Chlorination of overflows will reduce the bacteria count discharged
     into the river by combined sewer overflows  but will not reduce
     significantly, any of the other pollutional characteristics of the
     overflows.  Therefore, adequate treatment cannot be provided by
     chlorination alone.

Recommendat i ons

  I.  The  "Interceptor Sewer and Lagoon  System" for abating  pollution
     from combined  sewer overflows should  be adopted for Bucyrus.

     The  benefits from controlling pollution due to combined sewer over-
     flows by the use of an "Interceptor and Lagoon System" are many.

     (a)  Reduces pollution of the river both within the city of Bucyrus
          and downstream.

     (b)  Stream protection surpasses that to be achieved by combined
          sewer separation in that all  runoff up to the design storm
          will be intercepted and treated.

     (c)  Increases the value of the stream to the public in the City
          and downstream from the City.

     (d)  Reduces a health hazard within and below the City.

     (e)  A clean stream provides the possibility through use of  land-
          scape architecture to beautify the stream, enhance  its
          esthetic value and make  it a  real asset to the community.

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2.  The lagoon type of treatment should be demonstrated as capable of
    providing the degree of treatment required by constructing the
    "Off-Stream Treatment" concept as the first phase of the overall
    abatement program at Bucyrus, Ohio.

    The cost of the interceptor sewer represents a major portion of
    the "Interceptor Sewer and Lagoon System" method of abatement from
    combined sewer overflows.  The "Off-Stream Treatment" method of
    protecting the downstream water quality without regard for the
    inner-city reach of the river provides a method whereby the initial
    project cost can be reduced substantially.  The interceptor could
    be added for complete protection at a later date, as the final
    phase of the project.

    The City of Bucyrus is ideally situated in the Sandusky River
    watershed to demonstrate and evaluate pollution abatement from
    combined sewers on a watershed basis.

    (a)  There are no  large municipalities upstream to contribute
         pollutants.

    (b)  The  upstream  watershed of approximately 90 square miles  is
         used  for  general  farming.

    (c)  The  river downstream  from Bucyrus  is presently used by
         several cities as a source of water supply and the river  is
         destined  to  become  a  major source of water supply  in the
         future.

     (d)  The benefits  of  pollution abatement  from  sanitary waste  and
         urban storm  runoff  (combined  sewer overflow)  to  downstream
         water uses could be adequately  demonstrated.

     (e)  The reclamation  and  protection  provided a principal  river for
         all  downstream water  used would be  impressive and  could  be
         used as an example  for other  watersheds.

     (f)  Watershed protection  rather than pilot or scale  concepts is
         recommended  to  more fully evaluate the design storm,  hydraulic
         variables of  storm  runoff,  large scale operation cost,  etc.

    The  "Off-Stream Treatment" concept which  is proposed  as the  first
     phase  of the Bucyrus  project has many applications where the stream
     or river must  receive treatment  to achieve the desired  water quality
     standards.  A  full scale project  such as  proposed  at  Bucyrus would
     demonstrate the benefits to be  derived and design  criteria  could be
     developed which would be valuable  for other projects.

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"5.   The interceptor system should be constructed as the second and
    final  phase of abatement when it has been adequately demonstrated
    that the lagoon type of treatment is adequate and capable of pro-
    viding the water quality protection required.

4.   Until  such time as effective methods are constructed to control or
    eliminate the pollution problem the channels, waterways, or stream
    beds into which the overflows are discharged should be protected
    from erosion to prohibit the ponding of such overflows in pools
    which become septic and cause odors and are very unsightly.
    Periodic removal of debris from the stream channel especially  in
    the urban area should be accomplished at frequent  intervals.

5.   Municipalities with combined sewer systems should construct
    separated systems when extending service to new areas of growth or
    replacing existing sewers and new storm sewers constructed should
    be discharged to outlets other than existing combined trunk sewers
    where and when feasible.

6.   Automatic rain gauges, monitoring stations and sampling stations
    should be established both upstream and downstream  from Bucyrus on
    the Sandusky River to provide additional base  data  for future
    evaluation studies on abatement  projects undertaken.

7.   Install  continuous  level  recorders at the three overflow weirs that
    were constructed  for this  investigation.  These recorders will pro-
    vide a continuous  record  of  overflow volume.

8.  The officials of  the City  of Bucyrus should  be fully  informed  of
    the results of  this study  and the  recommendations  contained herein
    and that they be  given the opportunity  to participate  in a demon-
    stration project  for abatement of  pollution  from  their combined
    sewer system.

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                              SECTION I I

                             INTRODUCTION
To achieve the water quality standards established in Ohio for streams,
rivers and lakes all  of the communities with combined storm and sanitary
col lection systems have been placed under orders by the Ohio Water
Pollution Control  Board to seek methods of abating pollution from their
combined sewer overflows.   Physical separation of the system is of
course one acceptable method.

In a recent study to develop a total  water management plan for an area
of 9,144 square miles in northwestern Ohio, preliminary cost estimates
were prepared for the physical separation of combined sewer systems in
48 communities with a total population (1965) of some 812,000 persons.
In some instances the combined system may be converted to a separate
sanitary system and in others to a separate storm system.

The magnitude of the total project for making this conversion is demon-
strated by the $200,000,000 estimated cost to the 48 communities.  The
City of Bucyrus, Ohio, which was selected as a site for this study was
one of the 48 communities  included in the northwestern Ohio study.  The
estimated cost of combined sewer separation  in Bucyrus was $5,400,000
or $415 per capita using  1965-66 prices.

The Sandusky River flows through Bucyrus and discharges  into Sandusky
Bay and Lake Erie.  Future water management  plans for the principal
cities  in the watershed are based on  utilizing the natural flow  in the
river and upground storage reservoirs as the major source of water for
the area.  The  reduction  in the pollutants discharged  into the river
thus becomes very  important  if the desired water quality  is to be
achieved  and maintained for the intended use of the  river water.

The need  for pollution abatement due  to combined sewer overflows  is
evident.  There is need to determine  if there are methods of abating
pollution from  combined sewers which  would accomplish the task better
than physical separation  and  at a  lesser cost.

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                              SECTION I I I

                           PURPOSE AND SCOPE


The study is based on the possibility of interception of all or part of
the combined sewer overflow for treatment prior to release to the stream.
The advantages, disadvantages and economics of abating pollution from
combined sewer overflows by this method will be compared to physical
separation of the combined system.

One of the primary objectives of this study is to determine the relation-
ship of rainfall events to overflow events and the volume of flow in the
Sandusky River.  Once this relationship has been established, the design
storm with its resultant overflow rates, volumes and waste characteris-
tics can be selected for the design of the  intercepting devices and
treatment fac5 Ii t ies.

Research of historical  records of rainfall  and flow  in the Sandusky River
provided a pattern of rainfall and river flow which  could be used to
evaluate data  collected  during this  study period.  Available data on
water quality  in  the Sandusky River  was compiled.  Rainfall measuring
stations and Sandusky River  gaging stations were established to record
rainfall and river flows during  the  study period.

Weirs for measuring  overflows during rainfall were  installed at the over-
flow  points of three selected sewer  districts.   Samples were collected
during  selected overflow events  to determine  overflow characteristics
and effects on the stream.

The results of this  data collection  are  presented and discussed  in  the
following sections of this  report.   From  this data  the  facilities for
the collection and treatment of  combined  sewer overflows  have  been  sized
and cost estimates prepared  for  comparison  with  physical  separation
costs.

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                              SECTION IV

                              STUDY AREA
The City of Bucyrus, selected as a typical small midwest community with
a combined sewer system, is located on the Sandusky River near the upper
end of the 1,421 square mile Sandusky River Basin.  The river is tribu-
tary to Lake Erie as shown in Figure I.  The 90 square mile drainage
area upstream from Bucyrus is level agricultural  land.  Bucyrus is the
county seat of Crawford County,  and has an incorporated area of about
2,340 acres.  The City is located on an end moraine and the topography
is generally flat to slightly rolling.  The climate Is humid with warm
summers and mildly cold winters.  The mean annual temperature is 51  F
and the mean annual precipitation  Is 36 inches.  The Study Area is shown
in Figures I, 2, 3, 4, and 5.

Bucyrus has a tax valuation of approximately $40,000,000 and a  1968 tax
rate of 33.90 mills per $1,000.   The median income in Crawford County  is
$9,252 per year per household.

From  1920 through  1950 the population of  Bucyrus  remained practically
constant between 9,700 and  10,400  persons.  The  I960 census showed a
population of  12,276  persons and the current estimated population  is
13,000 persons.

The City  is moderately  industrialized.  Some of  the  larger  industries  are
Timken Roller  Bearing Company, Swan Rubber Company, General Electric
Company, Gal ion  Iron  Works and Manufacturing Company, Ryder Brass
Foundry, Cobey  Corporation, Bucyrus Blades,  Inc., Crawford  Steel Company,
Ohio  Locomotive and Crane Company, and  Bucyrus  Ice Company.

The water  supply  for  the municipal waterworks  system  is obtained from  the
Sandusky  River upstream from the City.  Water  is pumped from the River
and stored  in  upground  storage  reservoirs.  The  water treatment plant  is
a  lime-soda  ash softening plant.

The dry weather wastewater  in the  combined  sewer system  is  intercepted
at 24  points  along  the  river and conveyed downstream  in an  interceptor
sewer  to  the  wastewater treatment  plant.   The  plant  uses  the conven-
tional activated  sludge process  for treatment  of the  wastewater.   The
plant  effluent is  discharged  into  the  Sandusky River.  Most of  the
sewers are at  minimum grade due  to the  flat terrain.

The Sandusky  Rfver  downstream from Bucyrus is  a source of water supply
for the cities  of  Upper Sandusky,  Tiffin, and  Fremont.  At  the  present
time  there are  no  significant water  development facilities  on the  River
other  than  for these  public  water  supplies.  However, six (6) multi-
purpose upground  reservoirs  have been  proposed by the Ohio  Department
of Natural Resources  to provide water development for the area.  One of
the purposes  of this  reservoir  system is  to  provide  for a sustained flow

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of 3.75 MGD (5.7 c.f.s.) In the Sandusky River during a 20-year fre-
quency drought.  This would provide for increased public water supply,
for improved boating and fishing, and in a few places, for swimming in
the Sandusky River.  An area near Bucyrus is designated as a site for
one of these reservoirs.  The total design capacity of the proposed
Bucyrus reservoir is 2,054 million gallons, 476 million gallons for sus-
tained flow, 1,400 million gallons for public water supply and 178
million gallons for a conservation pool.  The total cost of the reser-
voir was estimated to be $2,458,000 in 1966.

The principal  pollution problems In the Sandusky River are sediment,
oxygen consuming materials, bacteria, phosphates and nitrates.  The
stream drains rich agricultural  lands which contribute significant
amounts of sediment and nutrients (phosphates and nitrates).  The area
around Bucyrus is intensely cultivated, the main crops being corn,
wheat, and soy beans.  Significant oxygen demand and high bacterial
concentration occur below Bucyrus due to discharge of treated and un-
treated sewage.  At the present time, all communities discharging
sewage effluents to the Sandusky River provide secondary treatment
facilities.
                                  12

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                               SECTION V

                           STUDY PROCEDURES
The procedures followed in accomplishing this study are discussed in the
order in which they were performed.

The overflows from the 24 sewer districts in Bucyrus could not be studied
in detail.  Therefore, a preliminary analysis of the districts was made
to determine which districts were representative.  The following items
were considered:  area, land use, hydraulics of the trunk sewers and the
interceptor, accessibility of the overflow points, and the availability
of channels to accommodate weirs for measurement of overflow volumes and
rates.  All overflow points and the wastewater treatment plant were
visited both in wet and dry weather.

Three districts were finally selected — Numbers 8 (179 acres),  17  (452
acres), and 23  (378 acres).  (See  Figures 2, 3, 4, and 5)  These are the
three largest districts  in Bucyrus, representing 64% of the total sewered
drainage  area.  They  include different  types of waste discharges in
varying proportions.

A detailed  analysis was made to determine the  drainage characteristics
of Numbers  8,  17,  and  23  sewer  districts.   Except  for the times  of  con-
centration, the characteristics of the  remaining districts were  esti-
mated by  comparing their  land use  to that of Numbers 8,  17, and  23  sewer
districts.  A topographical map and a sewer map  were used for  the analy-
sis.  The maps  were substantiated  by  in-field  observations.

A hydraulic analysis  of  the sewer  system was made  to determine the  flow
capacities of  the trunk  sewers, the connectors,  and the  interceptor.   A
 field survey  was  made of  Numbers 8, 17, and 23 sewer districts and  the
 interceptor.   The sewer  map was used  for the remaining  districts.   On
two occasions,  once  during dry  weather  and  once during  wet  weather, the
depth of flow in  the  interceptor was  measured  at several  points  and a
hydraulic gradient drawn.  The  Manning  equation, with  n = 0.013, was
 used to compute the  flow in  all pipes.

The existing meteorological  and hydro logical  records  for Bucyrus were
 obtained and  summarized  to establish  a  base line to which the data
 measured during the  study period could  be compared.   These  records
 included rainfall, river flow  and  quality,  and water and wastewater
 treatment plant flows and treatment plant efficiencies.  These records
 were obtained from the U. S.  Weather Bureau, the U.  S.  Geological  Survey,
 the Ohio Health Department, the Federal Water Pollution Control  Adminis-
 tration and the City of Bucyrus.

 A literature survey was made and a brief summary was compiled of the
 technical literature available on combined sewers.  Special  attention
                                    13

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was given to the technical  knowledge and operating experience of exist-
ing facilities similar to units suggested as part of the alternate
solutions.

An industrial waste survey was made to determine the type and volume of
waste to expect during dry weather and overflow sampling.  Only the
industries in the three study districts were surveyed.  Each industry
was visited and in-plant inspections made when necessary.

Two aquatic biology surveys of the Sandusky River were made to deter-
mine the type of aquatic life present as an indicator of water quality.
The surveys covered the section of the river from ten miles upstream to
thirteen miles downstream from Bucyrus.  The surveys were performed by
Rendell Rhoades, Chairman of the Biology Department, Ashland College,
Ashland, Ohio.  The first survey was in the fall of 1968 and the second
in the spring of 1969.

A system was established to alert personnel in Columbus, Ohio, of
approaching rain in Bucyrus.  By this system, personnel at the U. S.
Weather Bureau at Port Columbus, Columbus, Ohio, upon request, informed
project personnel of the probability, the type, and the time of arrival
of rainfall  in Bucyrus, six to twelve hours in advance.  This enabled
project personnel to  Install the necessary equipment and collect ini-
tial samples  from the sewers or the river prior to the arrival of the
rain.  Also  personnel of the City of Bucyrus notified project personnel
when the  rain  actually occurred in Bucyrus.

A continuous  record of the  rainfall on the three sewer districts during
the study  period was  obtained.  Three  rain gages were used, one  in each
of the three  sewer districts.  The gages were the weighing type, Bendix
Model 775C Universal  Recording Rain andSnowGage.  The charts had a  1:1
ratio for  rainfall depth and one chart  revolution equaled 24 hours.
The charts were changed weekly.  See Figure 6 for a picture of the rain
gage in Number 23 sewer district.

Samples and flow measurements were taken of the dry weather wastewater
flow discharged from the three sewer districts, the  influent and
effluent of the waste water treatment plant, and the  Sandusky River  at
the upstream and downstream gages.  The purpose of these samples and
flow measurements was to determine the average strength  and volume of
the waste at different times of the day and at different times of the
year.

A weir was installed  in each trunk sewer.  The weirs  were a 90  V-notch
weir, a 24 inch rectangular weir, and an  18 inch rectangular weir for
Numbers 8, 17, and 23 sewer districts, respectively.   (See Figure 7)
A sample was collected and the flow measured every  15 minutes for the
trunk sewers and hourly for the wastewater treatment  plant and river.
The samples were composited proportional to flow on an eight-hour shift
basis.  Both samplings were for 24 hour periods.
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A rectangular weir was built at each of the three overflow points to
measure overflow during rainfall.  (See Figures 7 & 8).  The weirs were
constructed of one-inch plywood, which was bolted onto steel angles
imbedded in concrete.  The weir plates were 8, 16, and 10 feet long for
Numbers 8, 17, and 23 overflows, respectively.

Water  level recorders were mounted in  instrument shelters 42 inches
behind the weirs.  The recorders were Stevens Type F Recorder, Model 68,
with a 9.6 time scale and a 1:2 gage scale.  All recorders were equipped
with automatic starters which would start the clocks at predetermined
water  levels.  The recorders were reset at least once every week.   (See
Figure 8)

The overflows from many storms were sampled during the study period to
determine the quality of the overflow and pollution  loads.  Only the
overflows from Numbers 8, 17, and 23 sewer districts were sampled.  From
July,  1968, through January, 1969, samples were collected manually.
After  February  I,  1969, Serco Automatic Samplers, Model NW-3, were
 installed  in the  instrument shelters at the overflows.  (See Figure 8)
These  samplers collected a 300 m.I. sample every five minutes for two
hours  during overflow.   If the overflow continued  longer than two hours,
samples were collected manually  at  less frequent  intervals.

An automatic starter  was devised  for the  samplers that started the  clocks
when the water  level  reached a  predetermined  height  behind  the weirs.
The samplers could therefore be  left unattended  prior to and during an
overflow.  The  samplers  required  a  vacuum be  maintained in  the sample
 bottles.   Because the samplers  would  lose the vacuum after  one or two
 days,  they had  to be  installed  within  24  hours   prior to the overflow.

 A continuous  record  of the  flow  in  the Sandusky  River  above and  below
 Bucyrus  was obtained  for the study  period.  An  existing recording gage
 operated  by the U.  S. Geological  Survey  located  at  the  first bridge
 below  the  wastewater treatment  plant was  utilized  for  downstream flow
measurements.   (See  Figure  10)   Through the cooperation of  the U. S.
 Geological  Survey,  project  personnel had  access  to the  recorder  and
 received  copies of the charts when  removed.   A new gaging  station was
 installed  on  the River 300  feet  upstream  from the  first overflow point
 on the combined sewer system.   (See  Figure 10)   A  rating  curve  for  the
 gage was  plotted using standard  gaging techniques.   Flow  metering equip-
 ment was  borrowed from the  U.  S.  Geological  Survey.  The  recorders  used
 at both  gaging  stations  were Stevens Type A35,  with  1:6 gage  scales.
 The time  scales for  the  gages  were  4.8 and 2.4 inches  per day,  for  the
 upstream  and  downstream  gages,  respectively.

 The Sandusky  River was sampled  above  and  below Bucyrus  during the study
 period to  determine  the  water  quality.  The  most commonly  used  sampling
 points were the upstream gage,  the  Au  Miller  Park ford,  and the  first
 six bridges  below the city.  All  of  the dry  weather samples and  some of
 the wet  weather samples  were collected manually.   A separate  sample for
                                   15

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dissolved oxygen was collected with a dissolved oxyqen sampler and the
temperature of the water measured.

After February I, 1969, the samples were collected at the upstream and
downstream gages during wet weather by Serco Automatic Samplers.  These
samplers were the same type as used for the overflows except they were
set to collect one sample per hour for 24 hours.  The samplers were
located on platforms overhanging the water.  (See Figure 6)  They were
installed and activated shortly before the rain started.  Additional
samples were collected for dissolved oxygen.

The Wastewater Treatment Plant bypass overflow measurement was deter-
mined by installing a recorder, float chamber, and instrument shelter
at the bypass manhole.  (See Figure 9)  This recorder measured the water
level in the chamber in relation to the invert of the overflow pipe.   A
rating curve based on the flow characteristics of the overflow pipe was
drawn.  The recorder used was a Stevens Type F Recorder, with a 1:1
gage scale and a 1.2 time scale.  The chart was changed weekly.

Laboratory analyses were performed on all overflow and river samples
collected for 18 different physical and chemical tests.  The parameters
analyzed were (I) biochemical oxygen demand (BOD), (2) chemical oxygen
demand (COD), (3) total solids, (4) suspended solids, (5) total volatile
solids, (6) volatile suspended solids, (7) total phosphates, (8) nitrate
nitrogen, (9) ammonia nitrogen, (10) organic nitrogen, (II) pH, (12)
alkalinity, (13) hardness, (14) chlorides,  (15) specific conductance,
(16) total coliforms, (17) fecal coliforms, and (18) fecal streptococci.
All laboratory tests were done  in accordance with the "12th edition of
Standard Methods for the Examination of Water and Wastewater".('^

Laboratory analyses of the samples were started immediately upon re-
ceiving the samples.  Samples that were not completely analyzed the
first day were preserved by acid and/or refrigeration.  When necessary
individual samples collected were composited according to the overflow
pattern.  The membrane filter technique was used for the total coliform,
fecal coliform and fecal streptococci tests.
                                  16

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                             SECTION VI

                       DRY WEATHER CONDITIONS
Collection System

Since the entire Bucyrus sewer system is combined, the system capacity
is adequate for the normal  dry weather wastewater flow.  There were no
complaints of dry weather odors or backups during the study.  In several
locations the system has been extended beyond the natural drainage
boundaries and the sewers are too shallow to permit gravity drains from
basements.

The major trunk sewers In the older sections of the city are of brick
construction; the remaining sewers are concrete or vitrified clay pipe.
All are laid close to or at minimum grade.  Because the  larger pipes do
not maintain scouring velocities at low flows, solids accumulate in the
sewers at many locations In the system.

Interceptor System

The Interceptor sewer system consists of control structures in the trunk
sewers which divert the dry weather flow through connector pipes to the
interceptor sewer.  The interceptor generally parallels the river through
the city to the wastewater treatment plant.  Two types of controls or
diversion structures are used.  One is a weir built across the combined
sewer pipe, the other is a depression  in the bottom of the pipe.  The
size of the connecting pipe regulates the amount of flow diverted.

All of the connector pipes flow by gravity  from the bottom of the trunk
sewer to the  Interceptor.  Most of the connectors are double or triple
the capacity  required for the normal dry weather flow.  There were no
reports of overflows during dry weather due to  insufficient connector
capacity during the study.

The main  interceptor is designed to handle  four to five  times the dry
weather flow.   It collects the flow from all 24 sewer districts and dis-
charges It to the wastewater treatment plant wet well and pump station.

The dry weather flows from Numbers 8 and 23 sewer districts were observed
overflowing directly into the river several times during the study period.
There were reports of other sewer districts also overflowing directly
Into the river at various times.   In each case the connector pipe was
plugged with a  large object or an accumulation of solids.  City personnel
reported some connectors require frequent cleaning.

Wastewater Treatment Plant

The Bucyrus wastewater treatment plant was  designed as a conventional
activated sludge plant.  The raw sewage  is  pumped from the wet well to


                                  17

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a comminutor then flows by gravity through an aerated grit chamber,
three circular primary settling tanks, three aeration tanks, and two
circular final settling tanks and to the Sandusky River.  The sludge is
anaerobically digested and dewatered on sand beds.  Plans are being pre-
pared for post-chlorination of the plant effluent in compliance with
orders from the Ohio Water Pollution Control Board.

The daily operational records of the treatment plant for the October,
 1968, to September,  1969, study period have been averaged and are sum-
marized below.

                   BOD - mg/l	      Suspended Solids - mq/l
               Raw   Settled  Final        Raw  Settled  Final

2.20           119    106      30         128     182      35

Sandusky River

The dry weather water quality condition of the Sandusky River varies
with the season and  flow.  During the winter and  spring months the flow
 in the river  is high and the river's condition is fair to good.  During
the summer and fall  months the flow  in the  river  is  low and the river's
condition  deteriorates.

 One half of a mile below the upstream gage  the water treatment plant
 discharges  lime  sludge  and wash  water  into  the river.  During high flow
 the  sludge  is carried  downstream with  no  noticeable  affects.  During
 low  flow the  sludge settles  out  on  the  bottom of  the river.   (See
 Figure  II)  Neither fish  nor aquatic insects can  survive  under these
 conditions.   The  sludge affects  the river for approximately a  distance
 of one mile,  or  to the  U.  S. 30  bridge.   Plans are  now  being  prepared
 for  lagoon ing the lime  sludge  and wash  water which  will  terminate  their
 discharge  to  the  River.

 The wastewater treatment  plant effluent has the  greatest  affect on the
 water quality of  the river during dry  weather.   During  the  months  of
 August, September,  and  October,  the flow  in the  river  is  too low to
 assimilate all of the  BOD  in the treatment  plant effluent.   Dissolved
 oxygen  levels are consistently below 4.0  mg/l for a  distance of five
 miles downstream  from  the treatment plant effluent outfall  and  fre-
 quently reach 0 mg/l during  the  night.   Sludge banks are formed on the
 river bottom  for  a distance  of three miles  downstream.

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                              SECTION VI I

                        WET WEATHER CONDITIONS
Col lection System

The Bucyrus sewer system has been extended beyond its original  design
capacity.   In at least one area the sewers are extended over the natural
drainage divide.  Many of the sewers have capacities which are  inade-
quate for an average one-year storm.  Therefore, there is street ponding
at several locations during the higher intensity rainfalls.

Except for the temporary inconvenience,  the street ponding does not
cause any problems.   A few corrections and additions to the system would
make it adequate for the present population.  However, the surcharged
sewers do cause backups in many homes through the basement drains.
There were several  reports of basements flooded with a mixture  storm
water and sewage during high intensity storms.

Interceptor System                                             i

The interceptor sewer has the same capacity as the sum of the connector
pipes flowing into  it at every point  in the system.  The total  pipe
capacity at the lower end of the system is  19 c.f.s., or four to five
times the average dry weather wastewater flow.

During a storm, however, the interceptor has a capacity only two times
the average dry weather wastewater flow.  The capacity is restricted by
the limited rates pumped to the wastewater treatment plant and the resul-
tant overflow level at the bypass manhole, all of which reduced the
hydraulic gradient of the sewer.

Two factors control the diversion capacity of the  interceptor during wet
weather.  One is the capacity of the connector pipes, and the other  is
the water  level in the interceptor.   From field measurements made during
an overflow, the hydraulic gradient for the flow  in the interceptor was
found to be high enough to affect the connector pipe capacities of many
of the sewer districts.  The flow in Number 5 connector pipe was
reversed, with the  interceptor overflowing through the .sewer district
overflow.  Very little overflow occurs at the wastewater treatment plant
in comparison to the volumes overflowing at the 24  individual sewer
districts.

The water  level in the interceptor during an overflow has contributed to
one problem.  Following the overflow the  interceptor remains full for
several days because of the  limited rate pumped to the wastewater treat-
ment plant.  The low velocities  in the trunk sewers, connector pipes and
the interceptor sewer allow the solids to settle out.
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The controls and overflows function as designed.  The depression type
of control appears to function better than the weir type of control
during wet weather.  The weir type control blocks part of the trunk
sewer and in some cases reduces its capacity by one-half.  All  of the
overflows are part of the original trunk sewer, and most of them are
equipped with flap gates to prevent back flow from the river during
high water.

Wastewater Treatment Plant

During wet weather the sluice gate to the wet well at the wastewater
treatment plant must be closed to limit the amount of flow into the
plant.  Experience has shown that when the gate is closed three-fourths
of the way,  the flow to the plant will be between 3.0 and 3.5 MGD.
This is the  maximum capacity of the plant.

During wet weather the BOD of the waste coming  into the plant decreases.
The increase in flow rate decreases the settling time and efficiency
and reduces the suspended solids content  in the aeration tanks.  The
quality of the effluent remains approximately the same, but the effi-
ciency of treatment decreases.

Sandusky River

All of the overflows discharge directly into the river.  The sum of the
overflows give a  very distinct hydrograph at the downstream gage.   If
the rainfall is a  localized thunderstorm, the river returns to  its
previous  flow.   If the  rainfall  is more generalized, the overflow hydro-
graph wiI I be followed  16 to  40 hours  later by  the hydrograph of the
runoff from the upstream drainage basin.

The water quality of the river during wet weather varies with the season
and flow.  The more flow in the river, the more dilution water  is avail-
able for the overflows.  Therefore, the condition of the river will be
the poorest following an overflow during  the summer and early fall
months.

The overflow wastes have several effects on the river.  The most obvious
one is the debris and organic solids which settle  in the river  in and
below the city.  These create odors and unsightly conditions long after
the overflow is past.  A second effect is the decrease  in quality of the
water moving downstream.  BOD's, solids, coliform, etc., are increased.
In turn, dissolved oxygen is decreased.  The aquatic  life is affected.
Therefore, the usefulness of the water for recreation and water supply
is impaired.
                                  20

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                             SECTION VIII

                METEOROLOGICAL AND HYDROLOGICAL HISTORY
The past meteorological and hydrological records for the Bucyrus area
and the Sandusky River have been reviewed and summarized to provide base
I ine data.

MeteoroIogj ca I  Hi story

Daily, monthly and annual  rainfall  data for Bucyrus were obtained from
the periodical  "Climatological Data" published by the Weather Bureau of
the U. S. Department of Commerce.  These records date back to 1931.  The
average monthly rainfall records since  1931 have been summarized and are
shown in Table I.  The average annual rainfall for the Bucyrus area is
35.7  inches.

In addition to summarizing the meteorological records since 1931, the
records for the ten-year period from January  1959 to September 1968 were
studied in more detail and used for comparison with the weather condi-
tions occurring during the study period.  The average monthly rainfall
for the study period  is shown  in Table  I and also graphed in Figure 13.
The average annual rainfall for the ten-year period is 32.8 inches.

For the ten-year  period studied  in detail, July had the highest average
monthly rainfall  with  3.88 inches and October the  lowest with 1.96
inches.  The wettest month during this  ten-year period was July, 1966,
when  9.29  inches  of rain fell while the driest month was October,  1963,
when  only a trace fell.

Detailed study of the  ten-year period  indicates that on the average there
are 75 days per year when the rainfall  is  greater than 0.10 inches, 22
days  per year when rainfall is greater  than 0.50 inches and six days per
year  when  rainfall is  greater than  1.00 inches.  Also, July is the
wettest month in  terms of amount and  intensity of  rainfall.

The weather bureau station at Bucyrus  reports only daily rainfall totals.
Due to the  lack of hourly rainfall  data at this station, intensity-
duration  information could not be developed.  Therefore, the "Rainfall
Frequency Atlas of the United States",  Technical Paper No. 40, published
by the U. S. Department of Agriculture, was used to develop rainfall-
duration-frequency relationships for the Bucyrus area.  Figure 14,
entitled "Rainfall Depth - Duration -  Frequency Curves" and Figure  15,
entitled "Intensity -  Duration Curves"  were derived from the above men-
tioned source.

Hydrological History

Data on flow rates in  the Sandusky River were obtained from the U. S.
Department of Interior Geological Survey publication titled "Surface


                                 21

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Water Records of Ohio" and the Ohio Department of Natural  Resources
Printed Bulletin No. 37, 40, and 42.  The Geological  Survey records
cover the periods August, 1925, to November, 1935; July, 1938 to
December, 1951; and December, 1963, to September, 1966.  The Natural
Resources summary is based on gaging records through  1965.

The average flow in the Sandusky River at Bucyrus is  80.2 cfs for the
26 years of records.  On a yearly bais, the minimum average flow of 33.8
cfs occurred in 1937 while a maximum average flow of  145 cfs occurred in
1959.

The average daily flows of the Sandusky River at Bucyrus are graphed in
Figure  12 for each month.  The contrast between the low daily flows in
July to November and the high daily flows in December to June is evident
from this graph.  The months  in order of decreasing average daily flow
are:  (I) March - 202 cfs,  (2) February - 151 cfs, (3) April -  150 cfs,
(4) January -  127 cfs,  (5) May - 86 cfs, (6) June - 82.5 cfs, (7)
December - 78 cfs,  (8)  November - 36.5 cfs,  (9) July 26.5 cfs,  (10)
August  - 18.8 cfs,  (II) October -  12.2 cfs, and  (12)  September - 9.6
cfs.

The maximum daily flow  ever observed was 4,600 cfs on December  14, 1927,
and the minimum of  0.6  cfs on September 29,  1941, and September 25, 1946.
The ten-year,  seven-day duration  low flow average discharge is 0.70 cfs.

Figure  13 compares  average  daily  flows  for  each  month with average rain-
fall for each  month.  Monthly flow  variation  is  shown to be much greater
than monthly  rainfall variation.   Maximum rainfall is  less than twice
the minimum  rainfall, while the  ratio  of maximum to minimum river flow
is over 20 to  I.

Only a  little  over  I  percent  of  the total annual  discharge of the
Sandusky River at Bucyrus occurs  during the month of September.  Five
percent of the total  annual  discharge  occurs  during the three month
period  - August to  October.   About  12  percent of the total annual dis-
charge  occurs  during  the  five month period  -  June to November.  Over 50
percent of the total  annual  discharge  occurs  during the three month
period  - February to  April.   The  minimum average monthly discharge, the
minimum average daily discharge  and the minimum  observed discharge all
occurred in the month of  September.

The flow duration probability values for the  Sandusky  River at  Bucyrus
are presented  in Table  2, entitled  "Percent of Time  Indicated Sandusky
River Flow at  Bucyrus  is  Equaled  or Exceeded".   This table  shows that
the median river  flow or  the  flow that is equaled or exceeded 50 per-
cent of the time  is 16.8  cfs.  The  median flow of 16.8  cfs  is extremely
lower than the average  flow of 80.2 cfs.
                                   22

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                               TABLE  I

              AVERAGE MONTHLY RAINFALL AT BUCYRUS, OHIO
                                               Inches of Rai nfalI
                                         1931 -  1968        1959 -  1968
January
February
March
Apri 1
May
June
July
August
September
October
November
December
2.88
2.34
3.15
3.18
3.35
4.50
3.22
3.23
2.73
2.40
2.45
2.24
2.52
2.12
2.34
3.55
3.37
3.09
3.88
2.28
2.52
1.96
3.10
2.11
Average Annual  Rainfall
35.67
32.84
                                 23

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                   TABLE 2

PERCENT OF TIME INDICATED SANDUSKY RIVER FLOW
     AT BUCYRUS IS EQUALED OR EXCEEDED
     Percent                Flow (cfs)
5
10
15
20
25
30
40
50
60
70
75
80
85
90
95
350
170
108
79.0
59.5
45.0
27.0
16.8
10. 1
6.10
4.75
3.80
3.05
2.43
1.80
                    24

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                              SECTION IX

                WEATHER CONDITIONS DURING STUDY PERIOD
Project personnel  made 16 wet weather trips to Bucyrus during the study
period July, 1968, to September, 1969, to collect samples of predicted
overflows.  There were 10 days out of the 16 that overflows actually
occurred and were sampled.

Grab samples were collected manually during 5 overflow events that
occurred prior to February 8, 1969.  Samples of the remaining 5 overflow
events were collected by automatic samplers and project personnel.

Rainfall Data for Study Period

The total rainfall per month that occurred during the study period is
shown in Table 3.  These monthly rainfall totals have been compared to
the past monthly averages and are presented in Table 3 as percentages of
average rainfalI.

The period November,  1968, through January, 1969, was wet, while February
and March,  1969, were dry.  April,  1969, marked the start of an unusually
wet four-month period.  The  rainfall  during these four months averaged
 162 percent above normal.

Sandusky  River Flow  During Study Period

A  summary of the  Sandusky River flow  during the study period is presented
 in Table  4.  This table shows the  average, minimum, and maximum river
 flow  for  each month  of the study period.  Also included  in the table  is
a  comparison of the  average  flow during  the study period with the his-
torical  average.  December,  1968 and  January,  April, May, and August,
 1969, were  extremely wet  months ranging  from  150 percent to  288 percent
above normal flow.
                                   25

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           TABLE 3




RAINFALL DURING STUDY PERIOD
Date
July 1968
August
September
October
November
December
January, 1969
February
March
Apri 1
May
June
July
Inches of
Rainfal 1
3.54
1.97
3.11
0.90
1.45
3.14
3.20
0.94
1.33
5.49
4.91
5.77
6.36
Percentage
Average Rainfal 1
no
61
114
38
159
140
III
40
42
173
147
128
198
             26

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                TABLE 4




SANDUSKY RIVER FLOW DURING STUDY PERIOD
Date
July, 1968
August
September
October
November
December
January, 1969
February
March
Apri 1
May
June
July
Average
cfs
27
9
9
6
33
146
197
106
62
272
248
50
60
Minimum
cfs
3
3
2
2
2
6
16
24
10
44
19
12
6
Maximum
cfs
330
95
310
36
350
1,800
1,650
700
400
1,850
2,800
275
435
Percent of
Past Average
too
47
90
50
91
187
150
70
66
182
288
62
222
                   27

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                               SECTION X

            DRAINAGE CHARACTERISTICS OF THE SEWER DISTRICTS
History
The Bucyrus sewer system started as a combined system.  Because the city
was built adjacent to the Sandusky River, drainage was not a problem.
The natural drainage system was converted to a combined sewer system
which discharged both storm and sanitary wastes directly into the river.
This led to the development of numerous small sewer districts along each
side of the river, each district with its own separate overflow.

In  1935, the wastewater interceptor sewer was built along the Sandusky
River.  Through control structures and diversion pipes, the sanitary
wastewater flow was collected during dry weather and discharged Into the
river at a point west of the city.  Later this flow was diverted from the
river to a wastewater treatment plant, thus completing the system.  The
system  is the same now as  in  1935, with the exception of improvements to
the wastewater treatment plant, which were constructed in  1961.

General Description

Bucyrus  is  located near the drainage  divide  between the Lake Erie and the
Ohio River Drainage  Basins, as  shown  in  Figure  I.  The change  in eleva-
tion  from  one end of the city to  the  other  is  less than 20  feet, except
 in  the  immediate  vicinity  of  the  river.  The topography resembles a
plateau  with the  river and its  flood  plain  winding through  it.  Most of
the building and  development  is on the  plateau  area.  Most  of  the sewers
are laid at minimum  grade, until  they reach  the edge  of the  flood plain.

The existing sewer system  is  composed of 24  separate  sewer districts as
shown  in Figure  2.   The  size  of the  districts  varies  from  2.5  to 452
acres.   The average  size  is 65  acres,  the median  size is 20  acres.   All
of  the  drainage  districts  border  on  the  river  at  some point, with the
exception  of Number  24.  The  trunk sewer to district  Number 24 was
 installed  after  the  interceptor system was  constructed and serves the
extreme northwest part of  the city.

The sewers in  all  of the existing sewer districts are extended to the
natural  drainage  divide  or adjacent  areas with the exception of Numbers
 I,  4,  17,  and  24.  Additional  wastewater or storm water could  not  be
 placed  into the  systems  without pumping.  Numbers I,  4, and 17 districts
cover the  extreme east  side of  Bucyrus.  Portions of  these districts
contain unsewered areas  which are occupied  by  the fairgrounds  and  farm-
 land.   The development of  this  land  will  require  adequate  means of
 drainage.
                                   29

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Detailed Description

A detailed analysis was made of the drainage characteristics of Numbers
8, 17, and 23 sewer districts.  This was done to relate the three
drainage districts to each other and to the drainage districts in any
other city.  During this analysis the sanitary drainage area, the storm
drainage area, the number and type of waste contributors, the land use,
the land cover, the area slope and the area shape were determined for
each of the three districts.  The storm drainage areas and land use
classifications were also determined for the other 21 sewer districts.
This analysis is summarized in Tables 5, 6, and 7.

The three sources of information for this analysis were topographical
maps of Bucyrus and the surrounding area, a sewer map of Bucyrus, and
field observations.  The topographical maps were prepared from aerial
photographs and were completed in the fall of 1968.  They have a hori-
zontal scale of I" = 200 feet and two-foot contour intervals.  All
streets and buildings were shown, as well as other topographical
features.  The City of Bucyrus sewer map has a horizontal scale of
I" = 300 feet and shows the locations of sewers and manholes, inverts
of manholes, and the size and grade of the sewers.  This map was field
checked where necessary.

The following procedure was used for the detailed analysis.  First, the
sewer systems were redrawn onto the topographical maps.  The topo-
graphical  maps were then taken to the field and a complete survey made
of the three  sewer districts.  Every street in the sewer districts was
inspected.  Each  property was  labeled as  residential, commercial,
industrial,  institutional,  undeveloped, or  railroad.  All non-residen-
tial  property and  residential  property  with unusual  land cover or area
•./ere  further  classified as  to  the  type  of  land cover.  This was done
by sketching  in the boundaries of  these  various areas and  labeling
them.  Many manhole covers  were  lifted  to determine the accuracy of the
sewer map.  Field checks were  made  around the boundaries of the drain-
age basins to determine which  areas actually drained  into their sewer
systems.

Following  are the definitions of terms  used for  land  use  in this study:

      residential   - any family dwelling  unit - one  for each one or two
                     family unit and one  for each  family  in multi-
                     family units.

     commercial    - all places of  business excepting those whose major
                     business  is the manufacture of  a product to be sold
                     elsewhere - one for each business occupying a
                     ground-level  storefront.
                                  30

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     industrial     - any place whose major business is the manufacture
                     of a product to be sold elsewhere - one for each
                     name regardless of number of separate properties
                     occupied.

     institutional  - all schools and churches

     undeveloped   - without permanent improvements

     railroad      - track area not owned by private enterprise

The remainder of the detailed analysis of the sewer districts was com-
pleted in the office.  First the boundaries of the sanitary and storm
drainage districts  were determined.  The boundaries were then plani-
metered to determine their areas.  The number of each type of property
in each district was counted.  The area of each type of land cover and
the total area were then measured.

More than half of the storm drainage area of each sewer district is
normal residential  property.  This property was not measured directly.
The sums of the areas of the other types of property were subtracted
from the total areas to determine the area occupied by normal residen-
tial property.  These residential areas were then divided by the number
of normal residences in each sewer district to determine an average  lot
size.  Spot checks were then made to determine the average  lot land
cover.   (See Table 6)

The three sewer districts were classified according to their land use.
All three districts contain residential areas.  Number 23 sewer district
is classified as suburban residential because of the  low density of
houses per unit of area.  Based on these classifications, the remaining
21 sewer districts were also classified.  The remaining districts were
compared to Numbers 8,  17, and 23 districts by comparing their land use
on the  large scale topographical maps.  These classifications and the
drainage areas of all the districts are given in Table 7.

The average slopes of the three drainage districts were determined by
dividing each district  into smaller drainage areas.  The average slope
of each of these smaller areas was determined by measuring the fall from
the remotest drainage point to the sewer outlet.  These values were then
weighted on the basis of their areas and an average slope computed.
(See Table 5)

The final part of the analysis of the sewer districts was the deter-
mination of the shapes of the three study areas.  This was done by
approximating the drainage areas with regular polygons.  Maximum widths
and lengths were measured.  (See Table 5)
                                  31

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                                TABLE 5
     GENERAL DRAINAGE CHARACTERISTICS OF SELECTED SEWER DISTRICTS

                                                 Sewer Districts
Number of Customers
Residential
Commercial
 Industrial
 Institutional
      Total

 Population*
 Population
 Persons / Acre

 Drainage Basin Slope
 Weighted Average - %                       0-85        0.65       0.25

 Drainage Basin Shape
 Maximum Length - feet                     3,600       8,600      8,000
 Maximum Width - feet                      5,000       4,500      3,600

 Ratio Length to Width                       O-7          '-9.        2'2


 * Based on 3.5 people per  residence
No. 8
577
14
4
3
598
2,020
11.7
No. 17
1,228
173
1
15
1,417
4,300
9.1
No. 23
561
23
5
1
590
1 ,960
5.0
                                  32

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                                TABLE 6

          LAND USE AND LAND COVER OF SELECTED SEWER DISTRICTS
Land Use - % of Total Area

Residential
Commercial
Industrial
Institutional
Undeveloped
Ra iI road
Streets
          Total

Land Cover - % of Total Area

 Impervious
     Bui Idi ngs
     Asphalt & Concrete
     Streets
     Water
           Total

 Pervious
     Weeds
     Lawn
     Packed  Earth
     Gravel
     Cornfield
           Total

 Normal  Residential  Lot

 Lot Area (sq.  ft.)
 Lot Dimensions (ft.)
 House  and Garage Area (sq. ft.)
 Asphalt & Concrete Area (sq.  ft.)
 Lawn Area (sq.  ft.)
 Gravel  Area (sq. ft.)
 Weeds  & Garden Area (sq. ft.)
No. 8
                                                  Sewer Districts
                                                     No.  17     No. 23
59.6
6.3
7.8
4.6
12.9
0.2
8.6
100.0
14.7
10.5
8.5
0
33.7
20.4
39.8
0.8
0.8
4.5
66.3
8,400
60 x 140
1,400
350
5,000
0
1,650
55.1
1 1.5
7.2
2.3
II. 1
3.8
9.0
100.0
14.1
10.6
9.0
0
33.7
18.5
35.3
0.9
10. 1
1.5
66.3
9,000
60 x 150
1,500
975
5,450
225
850
53.4
4.8
17.6
0.7
15.4
0.2
7.9
100.0
1 1.2
6.4
7.9
0.6
26.1
17.8
49.9
0.3
5.9
0
73.9
16,000
90 x 178
1,900
850
12,300
50
900
                                   33

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                                              TABLE 7
                                DRAINAGE AREAS AND CLASSIFICATIONS
District
   No.

    I
    2
    3
    4
    5
    6
    7
    8
    9
   10
   I I
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24

Totals
Sanitary Drainage
  Area - Acres
      188
      475
      395
Storm Drainage Area
Sewered Non-Sewered
73.3
2.5
19.4
113 82
32.1
21.0
3.2
179
3.0
7.1
6.2
41 .9
8.8
70.2
10.8
5.0
452 162
5.7
24.5
12.1
7.8
72.4
378
20.7
- Acres
Total
73.3
2.5
19.4
195
32.1
21 .0
3.2
179
3.0
7.1
6.2
41 .9
8.8
70.2
10.8
5.0
614
5.7
24.5
12.1
7.8
72.4
378
20.7
                            Classification
                           of Sewered Area*
SD
R
R
R
50$ R,
R
50$ R,
R
R
50$ R,
C
R
75$ R,
R
75$ R,
50$ R,
R
SR
R
SR
SR
SR
SR
SD




50$ C

50$ C


50$ C


25$ C

25$ C
50$








                         1,570
244
,814
*Symbols:
SD - Semi-developed
SR - Suburban Residential
 R - Residential
 C - Commercial

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                              SECTION XI

                    HYDRAULIC ANALYSIS OF THE SEWER
                        AND INTERCEPTOR SYSTEMS
Sewer Systems

The hydraulic analysis of the sewer systems consisted of two parts:  (I)
determining the maximum sewer capacities, and (2) determining the times
of concentration.  The Manning equation with n = 0.013 was used to com-
pute the flow and velocity in the pipes.

Because of the steady growth of the city many of the sewers have been
extended beyond the area for which they were originally designed.  In
some cases, the systems have been extended beyond the drainage divide.
The result has been street ponding and basement flooding during wet
weather.  Number 23 sewer district is an example.  In the southern part
of this district, the sewer system has actually been extended beyond the
drainage divide between the Sandusky River and the Little Scioto River.
In this area the combined sewer  is only three feet deep.  Because of the
flatness of the sewer grades and the small size of the pipes, the City
has limited the number of street inlets which results in ponding rather
than surcharging the sewer system.  However, there are frequent reports
of basement flooding in the area.

The maximum capacity of each of  the 24 sewer systems was computed.  (See
Table 8)  The main trunk sewer was the controlling capacity for most of
the sewer systems.  However, in  a few systems the flow is  limited by the
capacity of the sewers discharging into the main trunk sewer.  Number 23
sewer district is an example.

The times of concentration for alI 24 sewer districts were determined.
The time of concentration consists of two  parts:  (I) the time of over-
land flow, and (2) the time of concentration  in the sewer.  The time of
overland flow depends on the length of travel from the most remote area
in the  drainage district to the  nearest storm sewer  inlet, the type of
ground  cover, and the slope of the land.   These values were measured
for Numbers 8, 17, and 23 sewer  districts.  The times of overland flow
for these three districts were computed using the formulas given under
the hydrograph method in the ASCE Sewer Design Manual.2  A maximum of
30 minutes was assumed.  Assuming that these values were typical for
the city, they were then applied to the other 21 sewer districts.  The
time of overland flow was also determined  for the impervious areas.

The time of concentration in the sewer  is  equal to the travel time from
the most remote  inlet in the system to the point where the last  inlet
lateral joins the main trunk sewer.  These times were computed from the
velocities in the pipes, assuming that  the pipes were flowing full.
                                  35

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The summary of the values obtained for time of overland flow,  time of
concentration in sewer, and total  time of concentration Is given in
Table 8.  Also given is the total  travel time for each district.  This
value was determined by adding the time of concentration to the travel
time in the sewer from the last inlet lateral to the overflow.

Interceptor System

The existing interceptor system functions as designed.  There were no
reports of overflows during dry weather except when a connector pipe
became plugged.  An analysis of the hydraulics of the interceptor was
necessary to determine its capacity and function during wet weather.

During the dry weather sampling on October 9 and 10,  1968, a check was
made on the connector capacity of the three districts studied.  The
districts have a connector capacity equal to 0.9 cfs for Number 8 dis-
trict, 4.2 cfs for Number  17 district, and 3.4 cfs for Number 23 district.
These compare with a maximum dry weather flow, measured on March 5,
1969, of 0.5 cfs for Number 8 district,  1.0 cfs for Number 17 district,
and  1.4 cfs for Number 23 district.  Therefore, the connector capacities
for these three districts are more than twice the maximum dry weather
fIows.

The existing  interceptor pipe  is designed to handle a flow of  19 cfs at
the  lower end of the system.  At each point  in the system, the  inter-
ceptor  pipe capacity is equal to the sum of the connector pipe capac-
ities.  The wastewater treatment plant  records show that the  interceptor
has  a maximum daily flow  in the spring  of 4.5 cfs and an average daily
flow of 3.5 cfs.  Therefore, the  interceptor has a capacity equal to
four times the maximum hourly  flow and  five and one-half times the
average daily flow.

An overflow structure  is  located on the  interceptor near the wastewater
treatment plant.  During wet weather, flow to the plant  is controlled
at about 3 MGD.  Flows In the  interceptor which exceed 3 MGD are diverted
to the  river.  The overflow is a 30" corrugated metal pipe with the
invert approximately 5.5 feet above the  invert of the interceptor.  This
overflow is  located near the junction manhole for the northwest trunk
sewer.  There are two 24" overflows on the northwest trunk sewer at an
elevation only 0.8 feet above the wastewater treatment plant overflow.
These also act as overflows for the interceptor during wet weather.

The control structures for diverting the dry weather  flow consist of
two different types.  One type is a simple rectangular weir built across
the  trunk sewer pipe, and is usually made of bricks.  The connector
pipe to the interceptor is cut into the wall of the trunk sewer pipe.
When the connector pipe is surcharged to the height of the weir, over-
flow to the river will occur.
                                  36

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The other type of control structure consists of a depression in the
bottom of the sewer.  The connector pipe is cut into the bottom of the
depression, makes a right angle bend, and continues to the interceptor.
When the connector pipe  is surcharged to the level of the bottom of the
sewer, overflow will occur.  Most of the overflow structures are equipped
with flap gates at the mouth of the overflow to prevent the river from
flowing into the pipe during high river stage.   Numbers 8 and 17 over-
flows have the weir type control; Number 23 overflow has two of the
depression type controls.

Both types of control  structures have proven successful for diverting
the dry weather flow.   However, the weir type control structure is a
restriction in the trunk sewer pipe during high flows during an over-
flow event.  Most of the trunk sewers were designed to carry only the
flow from the upstream drainage system.  The weir, in many cases, covers
one-half the area of the trunk sewer pipe.  The effects of this were
seen during this study.  For example, every time the trunk sewer pipe
at Number 17 overflow  is flowing full, the cover on the manhole behind
the control structure  is blown off.  See Table 9 for a comparison of the
capacities of the trunk  sewers for Numbers 8, 17, and 23 sewer districts
with the control structure, without the control structure, and the maxi-
mum flows observed from  the overflows during the past year.
                                  37

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                                      TABLE 8

                          MAXIMUM SEWER SYSTEM CAPACITIES
                            AND TIMES OF CONCENTRATION


District
No.
1
2
3
4
5
6
7
8
9
10
1 1
12
13
14
15
16
17
18
19
20
21
22
23
24
Maximum
Sewer
Capacity
cfs
23
4
5
42
25
4
1
105
5
5
61
7
3
29
39
3
140
5
6
5
4
12
65
8
Time of
Overland
Flow
Min.
20
20
20
20
20
20
20
30
20
20
10
20
20
20
20
20
30
20
20
20
20
20
21

Time of
Concentration
in Sewer
Min.
14
1
7
15
9
7
1
24
2
4
4
6
3
16
5
4
34
4
18
6
7
12
39


Time of
Concentration
Min.
34
21
27
35
29
27
21
54
22
24
14
26
23
36
25
24
64
24
38
26
27
32
60
30
Total
Travel
Time
Min.
36
21
33
37
29
27
21
54
22
24
14
26
23
37
25
24
67
24
41
27
28
36
63

For Impervious Areas Only:

    8                       6
   17                       4
   23                       4
24
34
39
30
38
43
30
41
46
                                      38

-------
                               TABLE  9


                        MAXIMUM OVERFLOW RATES
                                      Maximum Overflow  Rate  -  cfs

Exi sting
System
50
75
65
Control
Structure
Removed
105
140
65
Measured
by
Weirs
50. 81
71. 02
7. .I3
   Sewer
District No.

     8

    17

    23
  Measured on July II, 1969, for a 25-year storm.

0
  Measured on April  5, 1969, for less than a 1-year storm.


3 Measured on July II, 1969, for a 25-year storm.  Also measured
  69.3 cfs on May 17, 1969, for less than 1-year storm.
                                  39

-------
                              SECTION XI I

                ANALYSIS OF RAINFALL AND OVERFLOW DATA
Tabulation of Hydraulic Data

The rainfall and overflow data recorded on the charts was transposed
into tabular form for study and analysis.  The rain gages recorded the
rainfall as a mass curve with the ordinate as total inches of rainfall
and the abscissa as time.  The smallest chart division of time was 20
minutes.  The charts were further sub-divided into five or ten-minute
increments for  low or moderate intensity  rainfalls.  For high intensity
rainfalls the charts were read from  inflection point to inflection
point.  Estimated accuracy of time readings are + 2 minutes, and
accuracy of setting the clocks to the correct time is + 5 minutes.  The
vertical total  rainfall scale was graduated to the nearest 0.05 of an
inch, and could be read to the nearest  .01 of an  inch.

Every rainfall  that had correspondingly good overflow records was tabu-
lated.  This  included the clock time, the number of minutes  in the time
interval, the accumulated rainfall as recorded on the charts, the rain-
fall  during that  interval, and the average  intensity of the  rainfall
during  that  interval.  When  no overflow  record was obtained, only the
total amount  of rainfall was  recorded.

The charts  from the flow  level recorders  recorded  depth of overflow above
the weir  plates versus time.  The depth  on  the vertical scale was gradu-
ated to the nearest 0.02 of  a foot,  and  could be  read to  the nearest
0.01  of a foot.  The time scale was  graduated to  the  nearest 15 minutes,
and could be  read to the  nearest 2 mintues.  When  there were rapid
fluctuations  in flow,  the charts were further sub-divided  into  five-
minute  intervals.  The accuracy of setting  0.00 on the  recorder chart
to the  top  of the weir plates was +  .01  of  a foot.  The accuracy of
setting the time  on the  charts to correspond with  the  correct time  was
+ 2 minutes.

The flow  records  were  also  recorded  in  a  tabular  form.  This included
clock time, minutes  in time  interval, depth of overflow above weir,
overflow  rate per foot of weir, total overflow  rate,  average rate of
overflow  for time interval,  overflow volume for  time  interval,  and
accumulated overflow volume  for overflow event.   Since  the flow  level
 recorders recorded height above weir rather than  flow,  these had  to be
converted to flow by use of  tables  for  rectangular weirs.

 Rainfall  versus Overflow Graphs

The next  step of  the data analysis  was  plotting  the  rainfall and  overflow
 data for  each overflow event recorded.   Both rainfall  and runoff  were
 plotted on  the  same  graph,  with  rainfall  plotted  above  overflow on  the
                                  41

-------
same time scale.  The rainfalls were plotted in the form of hyetographs,
the overflows in the form of hydrographs.  The time scale remained con-
stant for all graphs and the vertical scale varied according to the peak
rainfall  intensity and the peak overflow rate.  The rainfall and over-
flow graphs for March 24 and June 13, 1969, are given as examples in
Figures 16 through 21.

Each overflow hydrograph was divided into ten-minute segments.  The rate
of flow at the mid-point of each ten-minute interval was read and assumed
to be the average for that interval.  These values were summed to deter-
mine the total volume of overflow for the entire overflow event.  The
volume was then compared to the volume computed previously  in the tabu-
lation of the raw data to check its accuracy.  A summary of the rainfall
and overflow data was prepared for each of the three overflows for each
overflow event.   (See Tables 10, II, and 12)

Analysis of  Rainfall Data

The  rainfall data corresponding to the measured overflows were also
plotted as  intensity-duration  curves (See Figure 22)  These rainfalls
represent  a  variety  of  different types of storms.  May 7 and June  13
were short,  intense  thunderstorms.   April 5 and May  17 were long dura-
tion rainfalls, with short  periods of  intense  rain.  The majority of the
storms,  such as February 8  and March 24, were  of  light to medium  inten-
sity and  lasted between 2 and  12 hours.

None of  the  storms  measured  between  February  8 and  June  13,  1969, sur-
passed a  one-year storm over their  entire  length.   Two of the  storms did
exceed a  one-year storm at some  point.   May 17 exceeded  a one-year storm
during the maximum  12  minutes, and  June  13 exceeded a one-year storm dur-
 ing  the  maximum 38  to  80 minutes.

-------
         TABLE 10

RAINFALL AND OVERFLOW DATA
   NO. 8 SEWER DISTRICT
Date
2/8
3/24


4/5



28

5/7

8

17


6/13


8/9



No.

1
2
3
1
2
3
2,3
1
2
1
2
1
2
1
2
3
1
2
1,2
1
2
1,2
3

Total
Depth
In.

0.25
.14
.17
.10
.47
.30
.77
.03
.14
.16
.04
.09
.12
.27
.40
1.18
.39
.81
1.20
.13
.06
.19
.50
Rainfal 1
Avg.
Intensity
In./hr.

0. 14
.09
. 15
.60
1 .68
.60
.80
.09
.28
.32
.06
.23
.05
.23
.57
.51
1.56
.97
.90
.16
. 10
-
.40
Overf
Dura-
tion
Min.

1 10
90
70
10
17
30
57
20
31
30
40
23
140
70
42
138
15
50
80
55
35
-
75
Total
Vol .
cu.ft.

22,
20,
29,
10,
61,
31,
92,

II,
6,
2,



32,
172,
35,
96,
132,
6,
3,
9,
54,
No
400
300
300
000
300
400
700
No
300
800
300
No
No
No
000
000
200
900
100
400
100
500
000
1 nches
on
Basin
Record
0.034
.031
.045
.015
.094
.048
.141
Record
.017
.Oil
.004
Record
Record
Record
.049
.264
.054
.149
.203
.010
.005
.015
.083
low
Peak
cfs

3
4
7
5
22
1 1
22

4
3
1



19
32
19
27
29
2
1

22

.5
.6
.5
.7
.8
.0
.8

.8
.0
.1



.4
.4
.0
.2
.5
.7
.4

.7

Dura-
tion
Min.

150
180
160
70
105
95
125

1 15
107
65


220
185
325
100
175
200
100
60

140

%
Over-
f low

14
22
26
15
20
16
18

12
7
10



12
22
14
18
17
8
8
8
17
              43

-------
         TABLE I I

RAINFALL AND OVERFLOW DATA
   NO. 17 SEWER DISTRICT
Date
2/8
3/24


4/5



28

5/7

8

17


6/13


8/9



No.

1
2
3
1
2
3
2,3
1
2
1
2
1
2
1
2
3
1
2
1,2
1
2
1,2
3

Total
Depth
In.
0.17
.25
.14
.17
.09
.42
.26
.68
.03
.14
.16
.04
.09
.12
.27
.44
1.16
.37
.83
1.20
-
-
.30
.56
Rainfall
Avg.
Intensity
In./hr.
0.09
.14
.09
.15
.54
.93
.52
.72
.09
.28
.32
.06
.23
.05
.23
.29
.65
2.77
.91
.90
-
-
-
No Record
Overflow
Dura-
tion
Min.
120
1 10
90
70
10
27
30
57
20
31
30
40
23
140
70
92
108
8
55
80
-
-
-

Total
Vol.
cu.ft.
37,000
43,200
48,400
53,800
14,000
142,000
102,000
244,000
0
34,200
18,100
2,900
41,500
12,100
84,000
236,000
655,000

158,000
158,000
0
0
0
148,000
Inches
on
Basin
0.023
.026
.030
.033
.009
.087
.062
.149
0
.021
.Oil
.002
.025
.007
.050
.144
.400
Trace
.096
.096
0
0
0
.090
Peak
cfs
12.1
II. 0
13.5
12.0
14.6
71.0
40.5
71.0

18.9
24.5
2.2
29.2
2.7
28.0
66.5
64.0

63.2
63.2



50.1
Dura-
tion
Min.
105
135
135
145
80
95
100
135

85
60
40
80
102
135
415
265

190
190



110
%
Over-
f low
14
10
21
19
10
20
24
22
0
15
7
5
28
6
19
33
34
0
12
8
0
0
0
16
          44

-------
         TABLE 12

RAINFALL AND OVERFLOW DATA
   NO. 23 SEWER DISTRICT
Date
2/8
3/24


4/5



28

5/7

8

17


6/13


8/9



No.

1
2
3
1
2
3
2,3
1
2
1
2
1
2
1
2
3
1
2
1,2
1
2
1,2
3

Total
Depth
In.
0.24
.26
.16
.15
.10
.27
.17
.44
.04
.12
.20
.05
.11
.1 1
.22
.39
1.06
.18
.72
.90
No
.04
-
.36
Ratnfal 1
Avg.
Intensity
In./hr.
.10
.14
.09
.13
.60
.54
.41
.44
.12
.29
.55
.15
1.32
.05
.22
.59
.62
2.70
.85
.72
Record
.03
-
.31
Overflow
Dura-
tion
MIn.
150
115
110
70
10
30
25
60
20
25
22
20
5
130
60
40
102
4
51
75

80
-
70
Total
Vol.
cu.ft.
35,300
23,100
24,600
30,600
16,800
91,800
62,700
154,500
1,700
24,400
30,000
8,900
34,800
13,300
No
No
534,000
19,000
171,000
190,000
7,700
7,100
14,800
96,200
Inches
on
Basin
0.026
.017
.018
.022
.012
.067
.046
.113
.001
.018
.025
.007
.025
.010
Record
Record
.390
.014
.125
.139
.006
.005
.Oil
.070
Peak
cfs
8.5
5.2
6.0
7.8
8.1
32.3
20.0
32.3
1 .2
10. 1
13.2
4.4
15.1
2.3


69.3
II. 0
59.7
61.2
3.7
1.7

35.3
Dura-
tion
Min.
165
135
140
150
65
140
135
175
45
no
110
75
105
170


265
67
160
177
95
145

170
%
Over-
flow
II
7
M
15
12
25
27
26
3
15
13
14
23
9


37
8
17
15

13

19
           45

-------
                             SECTION XII I

                    WASTEWATER CHARACTERISTICS OF
            COMBINED SEWER OVERFLOWS AND RECEIVING STREAM


The sampling program for the collection of overflow and river samples
began in July, 1968, and continued through August, 1969.  From July,
1968, through January, 1969, flows were estimated and samples were taken
manually to determine the concentration range of water quality charac-
teristics.  The weirs at the three selected sewer districts were com-
pleted in January, 1969, and after that date the overflows were auto-
matically measured and sampled.  Table 13 presents the frequency and
duration of the sampling program and shows when and where samples were
collected and measured.  There were five days - February 8, March 24,
May 7, June  13 and August 9 - when overflow events were both measured
and sampled.

The  results of the laboratory analyses of all samples collected during
the  study period have been summarized  into a  number of tables and graphs,
each  of which will be discussed  in this section of the  report.

Dry  Weather  Sampling

Dry  weather  flow measuring and sampling to provide base  data on waste
 loads and  flow was done on October  9,  1968,  and  March  4,  1969.  The  dry
weather sewage flows  in sewer  districts Numbers  8,  17,  and  23 were
measured  and  sampled  at  15-minute  intervals  for  24 hours.   The  Sandusky
River,  upstream and  downstream,  was measured and sampled  at one-hour
 intervals  for 24  hours.   The  wastewater treatment plant influent  and
effluent  were sampled at  one-hour  intervals  for  24 hours  and  the  flow
measurements taken  from the plant  records.   The  samples were  composited
 into eight-hour shifts which  provided  three  composited samples  for each
samp I ing  point.

The  laboratory results of the dry  weather sampling have been  summarized
and  presented in  Table 14.   The  waste  loads  from the three sewer  dis-
tricts were fairly  consistent for  both sampling  days.   The BOD  waste
 load averaged 110 pounds  per day per 100  acres for the three sewer  dis-
tricts sampled.   This compares very close with the March 4, 1969, total
 dry  weather BOD at  the wastewater treatment  plant of 112 pounds per day
 per   100 acres of  sewered  area.  The suspended solids waste load averaged
 approximately 150 pounds  per day per 100 acres.

 The  October 9, 1968, samples showed an unusually high influent BOD at
 the  treatment plant.  A study of the laboratory results of the total
 sampling indicates  the unusually high BOD may have been caused by a slug
 of industrial waste from a sewer district other than those three sampled.
 Also, during the latter part of 1968, which  includes September and
 October,  the wastewater treatment plant was not operating effectively
                                   47

-------
and an unusually high waste load was being discharged into the river, as
indicated by the effluent BOD on the October 9th sampling.  However, this
problem was corrected and by January, 1969, the treatment plant was
operating normally.

The total coliforms averaged 44 million per 100 ml for sewer districts
Numbers 8 and 17, and 7 million per  100 ml for sewer district Number 23.
The lower count  in sewer district Number 23 is due to a large quantity
of industrial water.

Infiltration of  groundwater into the sewerage system can be estimated by
comparing the total flow received at the wastewater treatment plant on
the two dry weather sampling days.   The October 9, 1968, sampling
occurred during  an extremely dry month and represents conditions of
practically no  infiltration.  The total flow of 2.05 million gallons
received at the  wastewater treatment plant on October 9,  1968, agrees
closely with the water plant output  of 2.0 million gallons on the same
day.  The March  4,  1969, sampling occurred following spring thawing and
represents saturated  ground water conditions.  The flow received at the
wastewater treatment  plant on March  4 totaled 2.47 million gallons.
The water plant  output for this same period was 2.0 million gallons.
Therefore, the  infiltration  is the difference between the October and
March sampling  or  approximately 420,000 gallons.  This amounts to an
 infiltration rate  of  270 gallons  per day  per acre during the times when
the ground water table  is high.   This  infiltration rate is not unreason-
able  for a collection system.

Overflow Samples

The  laboratory  results of the  overflow  samples  from the three selected
sewer districts  have  been summarized and  presented  in Table  15.  This
table presents  the average,  minimum, maximum, and median  values of the
chemical and bacteriological characteristics of all the individual over-
flow  samples collected during  this  study.  Sewer  district Number 8 has
an average BOD  concentration of  170  mg/l  which  is considerably higher
than  the average BOD  concentration of  sewer districts Numbers  17 and 23,
each of which have an average  BOD of 107  and  108  mg/l respectively.
This difference  of  BOD concentration is due to  the fact that periodic
discharges of slaughter house  wastes occur in sewer district Number 8.
 It is interesting  to  note that there is very  little difference between
the average BOD  concentration of  the overflow samples and the average
BOD concentration  of  the dry weather samples.   However, the average
suspended solids concentration of 480  mg/l  for  the overflow samples  is
much higher than the  average of  160  mg/l  for the  dry weather samples.

The average total  coliform count  for Numbers 8  and  17 overflows was 8.8
million per  100  ml  and 16 million per  100 ml,  respectively.  This  is
only 20 percent  to 30 percent of  the dry  weather  sample total coliforms.
                                   48

-------
The more significant water quality character!sites of the overflow
samples, which include BOD, suspended solids, total solids, the nitrogen
series, total phosphates and chlorides, have been graphed in comparison
to time after start of overflow and are shown in Figures 23 through 43.
These graphs very clearly show the first flushing effects of the storm
water on the water quality of the overflows.  The peak concentrations
of the various water quality characteristics tend to coincide with the
peak overflow rate.

To determine the effects of settling on the overflow samples, two over-
flow samples from Number 17 sewer district were settled and the super-
natant withdrawn at 30-minute intervals for two hours.  The supernatant
was analyzed for BOD and suspended solids and the results are shown in
Figure 44.  The results indicate that approximately 60 percent to 70
percent of the BOD and suspended solids could be removed with 30 minutes
of sett I ing time.

A summary of the waste loads discharged into the Sandusky River from each
of the  five complete overflow events sampled and measured have been
calculated and summarized  in Table 16.  This table shows that the
August  9, 1969, overflow event discharged into the Sandusky River, from
just three sewer districts, 2,300 pounds of BOD in approximately two
hours.  This is more BOD than that received at the wastewater treatment
plant  from 24 hours of dry weather flow.  Extrapolating the 2,300 pounds
of BOD  to include all 24 sewer districts gives a total of 3,500 pounds
of BOD  discharged to the river.

Sandusky River Samples

The  laboratory analyses of the Sandusky River samples taken upstream and
at various  locations downstream, during wet and dry weather, have been
summarized and are presented  in Table  17.  Dry weather samples represent
conditions of the  river without overflow effects and wet weather samples
present the  river conditions  during times of overflow.  Because of the
difficulty  in treatment operation at the wastewater treatment plant
during  the  latter  part of  1968, mentioned previously  in this report,
only those  samples collected  after January,  1969 have been used in this
tab Ie.

The major differences  in the  upstream water quality characteristics dur-
ing dry and  wet weather are  in the suspended solids, nitrates and
bacteria counts.  The average dry weather suspended solids of 32 mg/l
increase to  an average 465 mg/l during wet weather.  The average dry
weather concentration of nitrates  is 7.2 mg/l as NO, and is increased to
an average 21.7 mg/l during wet weather.  This  increase  in nitrates seems
to be  due to agriculture runoff.  The total coliform count  is reduced
from a  dry weather average of 59,000 per  100 ml to 3,400 per 100 ml dur-
ing wet weather.  This reduction  in bacteria is due to the added dilution
water  from the upper drainage area.
                                  49

-------
The comparison between the dry and wet weather river samples indicates
that the waste loads from the overflow affect the river quality as far
downstream as the fifth bridge, which is approximately seven miles down-
stream from the wastewater treatment plant.  During periods of overflows
the average BOD  concentration at the first bridge downstream from the
wastewater treatment plant Is  increased from a dry weather average of
6 mg/l to 14 mg/l, the suspended solids increase from 49 mg/l to 192
mg/l, and the total coliforms  increase from a dry weather average of
400,000 per  100 mi Hi liters to 4.5 million per 100 mi Hi liters.  The
average coliform count at the  fifth bridge downstream from the waste-
water treatment plant  is  increased from an average 4,500 per 100
mi I I iliters to 86,000  per  100  mi IN liters.

The  diurnal  fluctuation of dissolved oxygen in the Sandusky River is
presented  in  Figures  45 and 46.  Figure 45 shows the dissolved oxygen at
the  upstream  gage  on  October 9 and  10,  1968, at the time of the first
dry  weather  sampling.  The dissolved oxygen ranged from 8.2 mg/l to
 10.3 mg/l and saturation  ranged  from 80 percent to 109 percent.  The
dissolved oxygen at the first  bridge downstream from the wastewater
treatment  plant  remained  at zero (0.0) mg/l for the entire 24 hour
period.

Figure  46  shows  the diurnal affect on dissolved oxygen in the Sandusky
River from the  upstream gage to  the seventh bridge downstream from the
wastewater treatment  plant, a  total distance of about 12 miles.  The
 river samples were taken  on August 5 and 6, 1969, during dry weather and
 river flow of approximately  10 cfs which  is considered low flow.  This
dissolved oxygen profile  shows the normal dissolved oxygen concentration
of the  river during  low flows.

 In addition  to  the two figures presented above, dissolved oxygen profiles
of the  river downstream from the wastewater treatment plant during both
wet  and dry  weather conditions are shown  in Figure 47.
                                  50

-------
  TABLE 13
DATA SUMMARY
Date
July 10, 16, 26 - 1968
" 18
September 5
" 12
" 16
" 24
October 2, 9
" 10
November 15
January 16, 17 - 1969
February 8
March 4, 5
" 20, 21
11 24
" 25, 29
Apr! 1 2, 28
ii 5
" 8, 15, 18, 19, 21
May 5, 9, 12, 19, 21
" 7
11 17, 18
June 3, 12, 16, 23, 26
" 13
11 14, 15
July 1, 8, 15, 22, 25, 28, 31
" 3, 5, II, 17, 27
August 1 , 6, 10, 20, 27
" 9
" 16
September 2, 6, 16
" 3, 9, 18
17
Overf lows
Measured










X


X
X
X
X


X
X

X
X

X

X
X
X

X
Overf lows
Samp led

X



X

X
X
X
X


X





X


X




X




River Sewer
Sampled Sampled
X
X
X X
X
X
X X
X X
X X


X
X X
X
X

X

X
X
X

X
X

X

X
X


X
X
      51

-------
             TABLE 14




SUMMARY OF DRY WEATHER WASTE LOADS


DATE & LOCATION
1.

2.
3.
4.
5.
6.


7.


Upstream
October 9, 1968
March 4, 1969
Sewer District #8
October 9, 1968
March 4, 1969
Sewer District #17
October 9, 1968
March 4, 1969
Sewer District #23
October 9, 1968
March 4, 1969
WWTP-RAW
October 9, 1968
March 4, 1969
WWTP-FINAL
October 9, 1968
March 4, 1969
Downstream - 1st Bridge
October 9, 1968
March 4, 1969
AVERAGE
FLOW
MOD
1.27
24.56
0.13
0.22
0.27
0.50
0.66
0.69
2.05
2.47

2.15
2.59

10.87
29.63
mg/l
2.2
3
192
121
198
118
60
84
232
109

105
24

42
6.0
BOD
Ibs/day
23
f 1 A
614
208
221
445
491
329
482
3960
1969

1882
518

3807
1482

Ibs/day/
100 ac


116
124
98
108
87
128
252
112






                 52

-------
       TABLE 14 (CONTINUED)




SUMMARY OF DRY WEATHER WASTE LOADS
SUSPENDED
SOLIDS

1.
2.
3.
4.
5.
6.
7.
mg/l
12
10
155
109
84
193
62
246
96
143
70
55
13
5
Ibs/day
127
2048
168
199
189
804
344
1417
1638
2941
1255
1 188
1 178
1235
Ibs/day/
100 ac.

94
1 1 1
42
178
91
375
104
187


TOTAL
SOLIDS
mg/l
593
442
768
753
738
862
287
758
847
755
735
822
673
457
TOTAL
VOLAT 1 LE
SOLIDS
mg/l
213
138
252
223
242
273
145
343
333
203
237
257
213
132
SPECIFIC
CONDUCTIVITY
mohos/cm
757
490
1,003
897
1,010
910
573
665
1,117
897
1,063
872
960
538
                53

-------
       TABLE 14 (CONTINUED)




SUMMARY OF DRY WEATHER WASTE LOADS


1.
2.
3.
4.
5.
6.
7.
_CQD
mg/l
36
63
516
318
781
304
660
537
628
201
327
253
192
46
TOTAL
COL! FORMS
per 100
ml
60,000
23,000
42 x 10^
33 x 10°
61 x IOJ?
42 x 10°
7 x 10*
7 x I06
10 x lo6.
200 x 10
4.2 x I06.
15 x 10°
6.5 x 10?.
1.5 x 10°
FECAL
COL 1 FORMS
per 100
ml
10,000
450
5 x 10*
3.0 x 10°
1.7 x 10*
4.2 x 10°
5.7 x I06
500,000
10 x 10?
8 x 10°
2.0 x I06
6.0 x I06
110,000
FECAL
STREP
00
ml
1,500
1,000
550,000
300,000
I.I x I06
350,000
110,000
18,000
1.5 x I06
360,000
270,000
26,000
320,000
17,000
                   54

-------
       TABLE 14 (CONTINUED)




SUMMARY OF DRY WEATHER WASTE LOADS


1.
2.
3.
4.
5.
6.
7.
NITRATE
NITROGEN
mg/l as N03
0.6
5.1
0.9
1.7
1.0
1.6
0.8
2.6
0.7
0.5
0.6
0.6
0.3
5.1
AMMON 1 A
NITROGEN
mg/l as N
1.2
0.4
55
30
56
35
38
21
48
30
58
24
43
1.8
ORGANIC
NITROGEN
mg/ 1 as N
Trace
2.0
36
33
48
27
14
16
34
21
31
22
17
3.0

mg/l
1.2
3.6
91 .2
62.9
104
62.4
52
37.4
82.5
47
89.1
51
60.4
5.4
TOTAL NITROGEN
AS N
Ibs/day
13
737
98
1 15
234
260
286
215
1410
968
1598
1 102
5475
1334

Ibs/day/
100 ac

55
64
52
57
76
57
90
62


                   55

-------
       TABLE 14 (CONTINUED)




SUMMARY OF DRY WEATHER WASTE LOADS
TOTAL PHOSPHATES
AS P04

1.
2.
3.
4.
5.
6.
7.
mg/l
0.5
0.6
82
13.7
47
19.2
8.7
8.7
31
19
31
19
17
1.6
Ibs/day Ibs/day/
100 ac
5
123
89 50
25 14
106 10
80 4
49 13
50 13
530 34
391 25
556
410
1541
395
CHLORIDES
mg/l as Cl
36
29
122
120
107
113
74
70
169
136
137
133
112
39
TOTAL
ALKALINITY
mg/l as CaCO,
251
159
330
249
300
243
160
155
249
216
227
218
233
170
PH

7.6
7.9
7.3
7.7
7.2
7.9
7.3
8.0
6.8
7.0
7.2
7.3
7.1
7.7
              56

-------
          TABLE 15

SUMMARY OF LABORATORY ANALYSES
      ON OVERFLOW SAMPLES
LOCATION
1 . Overflow No. 8
No. of analyses
Average
Minimum
Maximum
Median
2. Overflow No. 17
No. of analyses
Average
Minimum
Maximum
Median
3. Overflow No. 23
No. of analyses
Average
Minimum
Maximum
Med I an
BOD
mg/l

47
170
II
560
140

54
107
II
265
100

52
108
23
365
78
COD
mq/l

13
372
64
735
394

20
476
120
920
440

21
391
105
795
355
SUSPENDED
SOLIDS
mq/l

42
533
20
2440
360

44
430
90
990
400

32
477
120
1050
385
VOLATILE
SUSPENDED
SOLIDS
mq/l

13
182
70
440
180

24
238
80
570
160

20
228
70
640
200
TOTAL
SOLIDS
mq/l

40
1647
150
3755
1260

33
863
310
I960
780

25
916
370
1965
830
              57

-------
     TABLE 15 (CONTINUED)

SUMMARY OF LABORATORY ANALYSES
      ON OVERFLOW SAMPLES
NITRATE
NITROGEN
mq/l as M03
1. 41
4.54
0.05
13.50
3.30
2. 52
3.79
0.05
21.0

3.10
3. 49
3.89
0.05
21.50
2.40
AMMONIA ORGANIC
NITROGEN NITROGEN
ma/I as N mq/l as N
14
3
0
21
1
21
1
0
2

1
23
2
0
9
1

. 13
. 10
.3
. 10

.08
.10
.2

.1

.7
.10
.0
.8
14
10.3
2. 1
68
5.6
21
8.9
2.8
19.3

6.7
23
7.3
O.I
18.5
5.9
TOTAL
COL 1 FORM
/IOO ml

8.8
0.75
34.0
3.6

16
0.6
49

7.5

6.0
0.2
25
3.6
14
x
x
X
X
12
X
X
X

X
II
X
X
X
X
6
I06
I06
I06
10°

I06
I06
l°«
p\
10°
6
I06
[
10
6
I06
I06
I06
10
              58

-------
                       TABLE  15  (CONTINUED)

                   SUMMARY  OF  LABORATORY ANALYSES
                         ON OVERFLOW SAMPLES
TOTAL
PHOSPHATES
P04
mq/l f
TOTAL
ALKALINITY
mg/l
)H as CaC03
TOTAL
HARDNESS
mg/l as
CaC03
CHLORIDES
mq/l as
"ci
SPECIFIC
CONDUCTANCE
mohoms/cm
         31
         I I
          I
         35
          8.8
  .5
  .0
42
6.9
6.5
7.3
7.0
 31
127
 70
184
I 14
 31
183
I 15
290
168
  34
 203
  24
1400
  99
  42
1721
 200
4600
 810
2.
42
 9.0
 2.0
27.2
 7.7
47
7.1
6.6
7.4
7. I
 35
123
 40
280
I 10
 35
160
 58
290
150
  39
 120
   9
 460
 I 10
  39
 502
 132
 1500
 300
3.
41
10.5
 2.4
30
 7.5
47
7.0
6.6
7.4
7.0
 29
123
 64
250
100
 29
 176
 105
 260
 170
  31
 147
  12
 660
  71
  46
 825
 174
2100
 800
                                 59

-------
                   TABLE 16




SUMMARY OF WASTE LOADS FOR EACH OVERFLOW EVENT
                             FLOW

1.




2.




3.




4.




5.



OVERFLOW EVENT
DATE & OVERFLOW NO.
February 8, 1969
t 8
#17
#23
TOTAL
March 24, 1969
# 8
#17
#23
TOTAL
May 7, 1969
t 8
#17
#23
TOTAL
June 13, 1969
# 8
#17
#23
TOTAL
August 9, 1969
# 8
#17
#23
Overflow
Period
In
Minutes

120
105
165


150
135
135


107
60
no


200
190
177


140
no
170
Maximum
cfs

3.0
12.0
8.4


4.4
II. 0
5.2


3.0
24.5
13.2


27.8
63.2
61.2


22.7
50.1
35.3
Total
Vo 1 ume
1000 cf

13
37
35
85

22
43
23
88

7
18
30
55

132
158
190
480

54
148
96
     TOTAL
398
                     60

-------
             TABLE 16 (CONTINUED)




SUMMARY OF WASTE LOADS FOR EACH OVERFLOW EVENT


1.


2.


3.



4.


5.



Average
mq/l
120
51
86
146
161
104
I 18
172
1 16

41
31
36
177
112
1 12
BOD
Total
Ibs.
98
118
190
406
201
415
149
765
50
194
216
460
331
312
420
1063
600
1040
670
SUSPENDED
SOLIDS
lbs/100/
ac.
55
26
50
112
92
40
28
43
57

185
69
1 1 1
336
230
178
Average
mq/l
570
615
670
675
670
505
430
454
660

375
413
652
_
306
-
Total
Ibs.
464
1416
1480
3360
931
1539
725
3195
184
514
1234
1932
3100
4200
7700
14778
_
2850
-
lbs/100/
ac.
260
313
390
520
340
192
103
114
325

1700
900
2050
_
630
-
     2310
                     61

-------
             TABLE 16 (CONTINUED)




SUMMARY OF WASTE LOADS FOR EACH OVERFLOW EVENT
VOLATILE
SUSPENDED
SOLIDS
Average
mq/ 1
1.
_
-

2. 390
289
280

3. 200
291
368

4. 126
96
160

Total
Ibs.

_
-

540
779
404
1733
85
329
689
1103
1023
967
1873
TOTAL

PHOSPHATES
AS P04
Average
mq/l
8.3
6.7
6.5

12.0
11.3
11.8

7.3
12.2
15.1

2.3
2.0
9.7

Total
Ibs.
7
15
14
36
16
30
17
63
3
14
28
45
19
21
113
NITRATE

NITROGEN
AS N03
Average
mq/l
3.0
3.1
2.5

2.0
2.7
2.5

1.4
0.8
0.5

9.1
9.3
16.9

Total
Ibs.
2
7
5
14
3
7
4
14
1
1
	 |_
3
74
94
198
    3863
153
366
                      62

-------
                  TABLE 17




SUMMARY OF WET AND DRY WEATHER RIVER ANALYSES


1.





2.







3.






4.






5.








Sandusky River - Upstream
No. of analyses
Average
Minimum
Maximum
Med ian
Sandusky River - Downstream
1st Bridge downstream from
wastewater treatment plant
No. of analyses
Average
Mi nimum
Max i mum
Median
Sandusky River - Downstream
2nd Bridge from WWTP
No. of analyses
Average
Min imum
Max i mum
Median
Sandusky River - Downstream
3rd Bridge from WWTP
No. of analyses
Average
Mi n imum
Maximum
Median
Sandusky River - Downstream
5th Bridge from WWTP
No. of analyses
Average
Mi nimum
Maximum
Median
BOD
mq/l
Dry
Weather

33
4
1
14
3



27
6
2
12
5


9
7
3
22
-


12
4
1
8
4


13
5
2
13
4
1
Wet
Weather

22
5
2
13
4



43
14
4
51
10


8
5
3
8
-


17
6
3
10
6


19
6
2
12
6
SUSPENDED
mq/
Dry
Weather

20
32
5
160
20



14
49
8
190
22


8
44
10
195
22


4
36
27
45
-


5
18
15
25
17
SOLIDS
1
Wet
Weather

13
465
20
1 , 960
240



38
192
5
960
90


8
62
20
135
40


17
36
20
50
40


1 1
90
25
300
50
                     63

-------
            TABLE 17  (CONTINUED)

SUMMARY OF WET AND DRY WEATHER RIVER ANALYSES
TOTAL VOLATILE
SOLIDS
mq/l
Dry
Weather
1. 15
183
2
225
_
Wet
Weather
8
94
35
125
_
TOTAL
SOLIDS
mq/l
Dry
Weather
12
510
400
610
_
Wet
Weather
9
576
405
1,080
-
TOTAL PHOSPHATES
ma/I as P04
Dry
Weather
17
0.8
0.2
3.2
0.6
Wet
Weather
14
0.9
O.I
2.7
0.8
9
128
30
195
130
17
158
30
270
165
9
506
410
710
490
19
746
415
1,335
630
13
1.6
0.2
5.9
1.3
40
3.3
0.8
10.0
2.6
       2
     168
  2
480
3
2,0
6
2.2
                                    2
                                    2.0
                   15
                    4.1
                    1.8
                    8.0
                    4.8
                                             14
                                              3.7
                                              2.6
                      64

-------
                       TABLE 17 (CONTINUED)

           SUMMARY OF WET AND DRY WEATHER RIVER ANALYSES
NITRATE NITROGEN
	 mq/l as N03
Dry Wet
Weather Weather
AMMONIA
NITROGEN
mq/l as N
Dry Wet
Weather Weather
ORGANIC
NITROGEN
mq/l as N
Dry Wet
Weather Weather
I.
26
 7.2
 0.4
32.0
 3.3
19
21.7
 0.5
28.8
14.5
5
0.58
0.13
1.20
9
0.32
0.0
2.60
4
1.51
0.0
6.07
9
1.76
0.0
4.80
       20
        6.7
        0.2
       32.0
        3.3
          41
            7.5
            0.3
          24.8
            7.7
            5
            1.51
            I.10
            2.12
            1.51
           2.40
           0.60
           6.60
           1.40
          5
          2.40
          0.80
          3.03
          3.03
          3.79
          0.20
          14.7
          2.80
          .0
            6
            0.9
                                        .0
                                                          2
                                                          0.8
         4
         3.7
         1.3
         5.8
            15
             1.9
             0.5
             3.4
             1.8
         3
         6.9
         1.4
         10.2
            14
             6.2
             0.5
            22.2
             4.4
                       I
                       0.6
                                2
                                1.7
                                   65

-------
                  TABLE 17 (CONTINUED)

       SUMMARY OF WET AND DRY WEATHER RIVER ANALYSES
 TOTAL COLI FORMS
    /IQQ ml
             FECAL COL I FORM
  Dry
Weather
      3
 59,000
 23,000
 95,000
       86
0.4 x 10
   2,000,
1.5 x 10°
   Wet
 Weather
       4
   3,400
    1,200
   6,300
 4.5 x
0.05 x
 8.8 x
10
10
                           FECAL STREP
                              /100 ml
/ 1 UU
Dry
eather
3
8,000
450
14,000
6
36,000
2,000
110,000
fl I
. - •—•
Wet
Weather
— — H . .
3
900
800
1,000
7
161,000
10,000
320,000
_-- - i —
Dry
Jfeather
3
1,600
1,000
2,400
6
11,000
1,000
24,000
Wet
Weather
• — -•• " — •
3
170
130
200
6
55,000
1,000
157,000
        5
   15,000
    5,600
   40,000
         I
   130,000
            4
           390
           180
           500
  4
310
 70
500
1,400
        4
    4,500
    3,000
    5,300
         I
    86,000
             4
           380
           175
           760
  3
230
 180
300
                               66

-------
            TABLE 17 (CONTINUED)

SUMMARY OF WET AND DRY WEATHER RIVER ANALYSES

                                      TOTAL
COD                 pH              ALKALINITY
                                   mq/l as CaC03

1.




2.




3.




4.




5.




Dry
Weather
12
127
17
422

II
244
24
770
130
2
156
32
280
—
1
48
_
_
•~

_
_
-
_
Wet
Weather
4
65
18
164

14
1 14
28
220
120
4
156
24
430
80
4
112
18
210
—
5
86
24
220
-
Dry Wet
Weather Weather
26
7.9
7. 1
8.9
7.8
24
7.8
7.4
8.5
7.7
6
8.0
7.4
8.4
7.9
5
7.7
7.5
8.2
7.7
5
7.6
7.5
7.7
7.6
14
7.8
7.1
8.5
7.8
37
7.3
7.1
7.8
7.3
6
7.9
7.5
8.2
7.9
14
7.7
7.3
8.2
7.8
10
7.6
7.4
7.8
7.7
Dry
Weather
13
192
152
254
182
9
165
150
180
164
3
183
172
200

2
173
160
186

1
164
-
-
-
Wet
Weather
10
155
98
192
170
19
135
99
166
140
6
166
140
186

6
189
174
240

7
142
86
168
-
                      67

-------
                       TABLE 17 (CONTINUED)

            SUMMARY OF WET AND DRY WEATHER RIVER ANALYSES

                                               SPECIFIC
                                             CONDUCTIVITY
                                             	mohoms/cm
                                             Dry       Wet
     TOTAL
    HARDNESS
       as CaCQ5
  Dry       Wet
Weather   Weather
 CHLORIDES
 mq/l as C_l_
Dry       Wet
                        Weather   Weather    Weather	Weather
10
316
250
372
314
8
283
252
320
290
14
30
13
37
13
31
21
35
18
621
420
770
630
II
524
309
610
550
8
286
260
335
282
17
236
145
305
248
12
38
10
57
38
34
53
23
158
40
14
602
380
750
620
32
504
245
825
520
3
297
288
304
6
285
256
302
3
39
38
40
6
43
39
46
5
674
610
770
6
607
560
620
4.
2
270
240
300
6
293
272
304
3
44
37
50
14
56
37
77
5
651
580
725
14
653
600
742
5.
       268
7
271
185
296

5
60
37
69
65
9
47
22
74
43
6
639
563
720
688
9
581
370
740
600
                                   68

-------
                              SECTION XIV

             AQUATIC BIOLOGY SURVEY OF THE SANDUSKY RIVER
A summary of the aquatic biology survey of the Sandusky River is shown
in Table 18.

Sampling stations were established to determine biological productivity
and other pertinent information in the Sandusky River upstream and down-
stream from Bucyrus.  Samples were collected in the fall of 1968 and in
the spring and summer of 1969.  The study section consisted of 26 miles
of the Sandusky River extending ten miles upstream and thirteen miles
downstream and including three miles of river within the city.  The
stream population and stream conditions affecting biological produc-
tivity were observed at ten points.

The results of the aquatic biology survey corroborates the results of
the water quality studies of this report.  The river upstream from
Bucyrus has a relatively undisturbed fauna of the types normally found
in unpolluted waters.  The river  inside the City of Bucyrus shows
indication of gross pollution and has sections completely devoid of  life.
The river downstream from Bucyrus, during periods of low flow,  is bioti-
cally dead for six to eight miles below the wastewater treatment plant.
                                  69

-------
                                            TABLE 18
Date and Location

10 MIles Upstream
from Bucyrus
     March 18, 1969

Upstream Gage
     October 26,  1968
     March  18,  1969


     July 25,  1969
SUMMARY OF AQUATIC BIOLOGY SURVEY
      OF THE SANDUSKY RIVER

     Life Forms Founc[
Crayfish, snails and clams
Pea clams, snails,  leeches
minnows and crayfish

Crayfish, snails, pea clams
and muskrat

Crayfish, snails  and minnows
                                                                             Remarks
No evidence of pollution.


Gravel and rock bottom covered with
algae

Relatively undisturbed stream fauna.


River bottom has been washed clean
by recent  floods.
No.  8 Overflow
     October 26,  1968
      March  18,  1969
 Only  a  few  Immature  Insect
 larvae
 No apparent 11fe
Water plant waste  lime sludge had
filled most of the  niches  between
the  gravel and stone  river bottom.
Blue-green algae scum very apparent,

River very turbid  from  lime sludge.
01 I  siIck on  water.
 No.  17  Overflow
      October 26,  1968
 Pea clams, Phepa, leeches,
 crayfish, minnows and an
 array of immotile aquatic
 insects.
 Filamentacious algae extremely
 abundant.

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Date and Location

AuMIMer Park - 2000' Below
No. 17 Overflow
     October 26, 1968
     November  19,  1968
      March  18,  1969
      July 25,  1969
 Downstream Gage - First
 Bridge downstream from
 WWTP
      October 26, 1968
                                      TABLE 18 (Continued)

                                     Life Forms Found
Pea clams, Phepa, leeches
and crayfish
Pea clams, leeches, snails,
minnows and darters


Pea clams, crayfish and
snal I s
 Crayfish,  pea  clams,  leeches
 minnows, and various  forms
 of  plankton
 SIudge worms
                                             Remarks
This location contains a biotic
abundance including many forms of
algae and other plankton.  The
water is very clear.

A tremendous abundance of  life
forms.  River very clear at this
location.

The biotic abundance  found  In
October now  greatly reduced.  The
algae has been  swept  away  and rocks
are clean.

No evidence  of  pollution.   High
 flood waters have brought  river
 back  to  normaI.
 From a biotic standpoint, the river
 is dead.  The river is black and
 the stench is evident before one
 sees the stream.  Bottom of river
 is covered with black sludge
 deposits.
      November  19,  1968
 Sludge worms
                                                                    A dead river.

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K>
      Date  and  Location

      Downstream Gage  -  First
      Bridge  (Cont'd.)
           March 18,  1969
           July  9,  1969


           July  25,  1969
      Fourth  Bridge  Downstream
      5.5  mlles  below  WWTP
           October 26,  1968
           March  18,  1969

           July 25,  1969
      Fifth  Bridge  Downstream
      7.2  miles  below  WWTP
          November 19,  1968
      TABLE 18 (Continued)

     Life Forms Found



No 11fe forms found




No sample taken


Crayfish and minnows
SIudge worms
No Iife found

Crayfish, leeches, frogs,
minnows and various
plankton
Only immature insect
larvae
          Remarks
The river was rather clear and most
of the sludge deposits have been
washed out from the recent high
water.

High river flow and no evidence of
pollution.

Recent high waters have flushed out
sludge deposits and continued high
water has brought life forms.
Biologically, this location seems
more lifeless than the downstream
gage location.

River black and barren.

Flood water has cleaned river bottom
and brought in new life forms.
River was grayish and contained
sludge deposits.

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Date and Location

Eighth Bridge Downstream
9.6 mlles below WWTP
     November 19, 1968
     March 18, 1969
     July 25, 1969
Tenth Bridge Downstream
12.9 mi les below WWTP
     November 19, 1968
     March 18, 1969
      TABLE 18 (Continued)

     Life Forms Found
Caddis Larvae
Crayfish and all types of
aquatic insects

Crayfish, clams, minnows
and aquatic insects
Minnows, sunfish, crayfish,
caddis and aquatic Insects

Minnows, various types of
fish, crayfish and aquatic
insects
                                                                             Remarks
Caddis larvae indicate the stream
Is returning to normal.  River was
clear and there was no evidence of
sludge deposits.

No evidence of pollution.
River In good condition.
River is fully recovered at this
location.

River is fully recovered at this
location.

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                              SECTION XV

                  RELATIONSHIP OF RAINFALL AND RUNOFF
The design of interception and treatment or holding facilities for com-
bined sanitary and storm runoff water requires a complete sewer
hydrograph.3  This requires knowing the rainfall-runoff relationship.
Sewer hydrographs were developed first for the three sewer districts
studied in detail, then for all of Bucyrus.  Throughout the discussion
the word "overflow" will be used for any water flowing into the river
from the sewer system and "runoff" wi I I  be used for any water flowing
into the sewer system.  Overflow is assumed to equal runoff for rain-
falls greater than 0.25 inch.

There are three relationships between rainfall and runoff which must be
determined before a complete runoff hydrograph can be defined:  one, the
relationship of the start of the runoff hydrograph to the start of the
rainfall; two, the relationship of the shape of the runoff hydrograph to
the duration of the rainfall; and three, the relationship of the peak a
and volume of the runoff hydrograph to intensity and duration of the
rainfall.  Whenever possible these relationships will be derived from
the measured data.

Start of Overflow

A table was prepared for each of the three selected overflow points  list-
ing all of the overflow events measured.   Included  in these tables were
the times between the start of the significant rainfall and the start of
the overflow.  The period of time varies with the rainfall intensity and
pattern.  The following values present in Table  19 are average for rain-
falls of  intensities greater than 0.5 inch per hour.
                               TABLE  19

                       TIME TO START OF OVERFLOW

                                       Time Between Start of
                Sewer             Rainfall and Start of Overflow
             District No.         	Minutes	

                  8                                10

                  17                               20

                 23                               25
                                  75

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The time between the start of the significant rainfall and the start of
the overflow could be called the reaction time of the sewer system.   It
is equal to the period of time for a significant amount of runoff to
reach the overflow point.

Before  runoff starts, the depression storage must be  filled.  The runoff
needed  to cause overflow  is equal to the storage capacity  in the system
and either the volume of  the  interceptor or the capacity of the connector
pipe.   An analysis was made of the rainfalls producing  little or no over-
flow and having no antecedent rainfall.  The following values presented
in Table 20 are the  average amounts of  rainfall required to cause over-
flow:
                                 TABLE  20

                        RAINFALL TO CAUSE  OVERFLOW

                                          20-Minute RainfalI
                    Sewer           Required  to  Produce Overflow
                 District No.        	Inches	

                      8                          .04

                     17                          .06

                     23                          .05
 Hydrograph  Shape

 The unit hydrograph was used to describe the shape of the overflow
 hydrographs from each of the three areas.   Each  unit hydrograph was
 derived from the measured overflow data.  Only the overflows from short
 Intense rainfalls were used.  In many cases the  rainfall events produced
 compound hydrographs.  These hydrographs were separated and drawn as
 individual  hydrographs.

 Each overflow hydrograph was divided into ten-minute  Intervals.  The
 average rate of  flow in each ten-minute interval  was determined and the
 total  volume of  overflow computed.  The hydrograph ordinates were then
 adjusted to give a total  overflow volume equivalent to  1.00  inch of run-
 off from the sewer district.

 Every  overflow hydrograph for each sewer district then had the same
 volume,  but many different shapes.  The shape of  the hydrographs is deter-
 mined  by the length of the rainfall.   According  to the unit hydrograph
 theory,  any rainfall  less than the length  of a unit storm will produce
 the  same shape hydrograph.   If the rainfall  continues past this critical
 period of time,  each  additional  period of  unit storm will produce a unit
                                  76

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hydrograph;  the  sum of  these  unit hydrographs will  produce the hydro-
graph for that  rainfall.   Each  additional  unit hydrograph will  delay
the peak of  the  runoff  hydrograph by the duration of the unit storm.
Therefore, the  period of  time from the start of the overflow to the
peak of the  overflow will  equal  the period of significant rainfall  for
any rainfall  equal  to or  greater than a unit storm.

A graph was  prepared for  each overflow, plotting the length of the
significant  rainfall in minutes versus the time between the start and
the peak of  the  overflow  in minutes.  (See Figure 48 for the summary
of these graphs)  For Number 8 overflow, the length of significant
rainfall was equal  to the peak time.  However, for Number 17 overflow
the peak time is five minutes less than the  length of the significant
rainfall, and for Number  23 overflow the peak time was five minutes
greater than the length of the significant rainfall.  These variations
in peak time for Numbers  17 and 23 overflows were due to the  longer
lengths of time to start  overflow (See Table 19) and variations in the
drainage characteristics.

The smallest periods of time between the starts and the peaks of the
overflows measured were five minutes for Number 8 overflow, two minutes
for Number 17 overflow, and ten minutes for  Number 23 overflow.  (See
Figure 48)  The maximum length of significant rainfall producing these
minimum peak times were five minutes for Numbers 8 and 23 overflows,
and seven minutes for  Number 17 overflow.  Since five minutes was also
the shortest time of significant rainfall measured, the conclusions
are the length of a unit  storm  is equal to or  less than  five minutes
for Numbers  8 and 23 overflows, and  is equal to seven minutes  for
Number  17 overflow.

A unit hydrograph for each overflow  was derived from the overflow hydro-
graphs.  These unit hydrographs were based on the  hydrographs  produced
by rainfalls less than or equal to the unit  storm  for the sewer dis-
trict.  The  values  given  in Figure 48  for the times between the start
of an overflow and  its peak were used.  Twenty minute  lengths  of rain-
fall were later found  to be more convenient  to work with than  the unit
storm  lengths of rainfall.  Therefore, the unit hydrographs for 20
minutes of rainfall were summed to equal one hydrograph  for each over-
flow.   (See Figures 49, 50, and 51)  These hydrographs  have a  volume of
 1.00  inch of runoff and will be referred to  as "20 minute unit hydro-
graphs"  in future discussion.

Hydroqraph Peak and Volume

The two most important elements of a runoff  hydrograph  are  its  peak and
volume.  The two cannot be separated.   Since the  shape  of the  hydrograph
has already been determined, knowing either  the  peak or the volume  of
the hydrograph  will completely  define  it  for any  rainfall.
                                  77

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The two most commonly used methods for determining the peak or the volume
are:  (I) the rational formula and (2) the hydrograph method.  The appli-
cation of both of these methods to the three sewer districts in Bucyrus
was studied and the results compared to the measured data.  Finally a
modification of the hydrograph method was studied and adopted for use in
designing storm water facilities for Bucyrus.

I.   Rational Formula

The rational formula  is the most commonly used method for designing storm
water facilities.  The formula is easy to understand, simple to use, and
coefficients and variables are available from standard references for
either preliminary or detailed design.  The most  frequent objection to
the rational formula  is that only a peak rate of  flow can be computed.5
This objection would  be overcome  if used with the derived unit hydro-
graphs.

 In  its most commonly  used form, the rational  formula  appears as Q = CIA,
"Where Q is the  rate  of  runoff at a specific  point  in time,  A  is the
drainage area  tributary  to the specific  point at  the  specific time,  I is
the average intensity of  rainfall over the  tributary  drainage area for
the specified  time,  and  C is  the  coefficient  of  runoff  or ratio of rate
of  runoff to rate  of  rainfall  applicable to the  particular  situation."4
The specified  time referred to in the definition  of  I equals the time of
concentration.   In other words,  the  rational  formula  states  that the
 rate  of  runoff is  equal  to the rate  of  supply if  the  length  of rainfall
 is  greater than  the time of concentration.

Since  this study involves only the  wastewater discharged to the river,
only  the runoff  at the overflow  point for each  sewer district was deter-
mined.   The values for sewered areas  given  in Table 7 were  used for A.
The values of  I  used  were obtained  from  the intensity duration curves
for Bucyrus, Figure 15,  using the times  of  concentration obtained  from
Table  8.   Values for  C were still  required.

The preferred  method  of  obtaining a C value for  the three sewer districts
 is  to  use measured rainfall and  runoff data.   However,  this method was
found  to be impossible without studying  the sewer systems in great detail.
The times of concentration given  in Table  8 are  54  minutes, 64 minutes,
and 60 minutes for Numbers 8,  17, and 23 sewer  districts, respectively.
These  times of concentration  exceed the  length of any continuous  rain-
fall measured  during  the  past year  for the  three  overflows  with an
 intensity greater  than 0.20  inch  per  hour.   Therefore,  the only way  to
obtain a C value by this  method would be to determine by a  complete
hydraulic analysis how much of the sewer district area  was  contributing
at  the time the  rainfall  stopped.  An analysis of this  type exceeds  the
 realm  of this  study.  Therefore,  values  of  C  for  various types of  land
cover  have been  assumed,  based on published data, and matched  to  the
types  of land  cover for  the three sewer  districts.2  The C values  used
are presented  in Tables  21 and 22.
                                   78

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                               TABLE 21

                          RUNOFF COEFFICIENTS

Impervious                                               C_

     Bui I dings (roofs                                   0.85

     Asphalt and Concrete (drives and walks)            0.80

     Streets (asphalt and brick)                        0.80

     Water                                              1.00

Pervious

     Lawns (heavy soil  - 2%)                            0.15

     Weeds (unimproved areas)                           0.20

     Packed earth (playgrounds)                         0.30

     Gravel (railroad yard areas)                       0.30

     Corn Fields                                        0.20
Using the values for sewered area, given in Table 7, a weighted value
of C for each of the three sewer districts was obtained.  (See Table 22)
                               TABLE 22

                     WEIGHTED RUNOFF COEFFICIENTS

                 Sewer District            Weighted C

                       8                      0.39

                      17                      0.41

                      23                      0.35
These values compare well with other values of C given for residential
type areas.  For example, Linsey gives a C value for flat residential
area, 30 percent impervious, of 0.40.5  This compares to 0.39 and 0.41
for Numbers 8 and 17 sewer districts, each with 33.7 percent impervious
area.  Since Number 23 sewer district is only 26.1 percent impervious,
it has a lower C value.
                                 79

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The  runoff  to  be  expected  from a one year  frequency storm was computed
using the weighted  values  of C.  (See Table 23)  The runoffs from the
total  area  and just the  impervious areas are given.  These values are
compared to the measured runoff from the May 17 and June  13 storms.

From Table  23  two things become evident.   First, it is possible to get
a  higher peak  from  the  impervious areas alone than from the total areas.
The  intensity  duration curves for high  intensity storms drop so rapidly
during the  first  20 to 30  minutes that the peak overflow rate from a
smaller area with a shorter time of concentration can be greater than
the  peak rate  for the entire area.

Second, the  computed peak  flows for both the impervious areas and the
total  areas  are more than  double the flows measured on May 17 and
June 13, and far exceed the maximum capacity of the sewer system.  Since
the  peak overflow rates for Numbers 17 and 23 sewer districts were close
to the maximum sewer capacities on May  17 and June 13, a comparison of
these  values to the computed values cannot be made.  However, the peak
overflow rates for Number 8 overflow on these two dates are 20 cfs less
than the maximum sewer capacity.   Therefore, the conclusions are the C
value  for Number 8 sewer district is less than one-half the standard
value for this type of area.

A check was made on the maximum sewer capacities of all the sewer dis-
tricts using a two-year storm.   (See Table 24)  The classifications
given in Table 7 were used  to estimate a C value for each of the other
sewer districts based on the weighted C values obtained for Numbers 8,
17, and 23 sewer districts.  Nineteen of the twenty-four trunk sewers
have capacities less than the peak  runoff from a two-year storm.

The conclusions from the above  analysis are that the rational  formula is
not an acceptable  method of computing the runoff from the sewer districts
in Bucyrus.   First,  the peak flows  for a two-year storm exceed the maxi-
mum sewer capacities of many of the districts.   Second, the peak flows
computed with the  standard  runoff coefficients that do not exceed the
maximum sewer capacities are much greater than the  measured values.
Finally, with the  rational  formula  there is no simplified way of deter-
mining how much of the area is contributing for rainfall  durations less
than the times of  concentration.
                                  80

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                               TABLE 23
                  COMPARISON OF THE RATIONAL FORMULA
                           TO MEASURED DATA
No.  8 Sewer District
Rational  Formula
     Entire Area
     Impervious Only
May  17, 1969
June 13,  1969
Max. Sewer Capacity*
No.  17 Sewer District
Rational  Formula
     Entire Area
     Impervious Only
May 17, 1969
June 13,  1969
Max. Sewer Capacity*
No.  23 Sewer District
Rational  Formula
     Entire Area
     Impervious Only
May  17, 1969
June 13, 1969
Max. Sewer Capacity
Time of
A Concent.
Acres min.
178.9 54
60.4 30



452.5 64
151.5 38



377.8 60
98.5 43



1 C Q
1 Yr. Storm
in/hr. cfs
1.08 0.39 75
1.57 0.82 78
32
30
50
0.95 0.41 176
1.36 0.82 169
67
63
75
1.00 0.35 132
1.26 0.82 102
69
61
65
 * With Control Structure

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              TABLE 24

OVERFLOW PEAKS USING RATIONAL FORMULA
      2 Year Storm for Bucyrus

Sewer
District No.
1
2
3
4
5
6
7
8
9
10
1 1
12
13
14
15
16
17
18
19
20
21
22
23
24

A
Acres
73.3
2.5
19.4
113
32.1
21.0
3.2
178.9
3.0
7.1
6.2
41 .9
8.8
70.2
10.8
5.0
452.5
5.7
24.5
12.1
7.8
72.4
377.8
20.7
Time of
Concent.
min.
34
21
27
35
29
27
21
54
22
24
14
26
23
36
25
24
64
24
38
26
27
32
60
30

1
in/hr.
1.5
2.4
2.1
1.8
2.0
2.1
2.4
1.3
2.3
2.2
2.9
2.1
2.2
1.7
2.1
2.2
1.2
2.2
1.7
2.1
2.0
1.9
1.2
2.0

C
.25
.40
.40
.40
.60
.40
.60
.39
.40
.60
.80
.40
.50
.40
.50
.60
.41
.35
.40
.35
.35
.35
.35
.25

Q
cfs
27.5
2.4
16.3
81.3
38.5
17.6
4.6
90.6
2.8
9.4
14.4
35.2
9.7
47.8
11.3
6.6
222.5
4.4
16.7
8.9
5.5
4.8
158.7
10.4
                  82

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2.  Hydrograph Method

The most widely used hydrograph methods are the Los Angeles Method^ ancl
the Chicago Method.7  Both of these methods are for the design of an
entire sewer system, catch basin by catch basin.  The hydrographs for
each sewer lateral  are summed and the composit hydrograph peak used for
design.

Since unit hydrographs have been derived for the overflows of the three
districts, a composite hydrograph was not needed.  However, the surface
infiltration curves used to determine the volume of runoff from each
small drainage area can be applied to the entire drainage area provided
the area of each type of land cover is known.

The results by using the standard infiltration-capacity curve from the
ASCE design manual   for a pervious surface in a standard residential
area was compared with observed data.  This curve was plotted in terms
of accumulative mass infiltration capacity and checked against the rain-
fall and runoff data for Number 17 overflow on May 17 and June 13.  Mass
diagrams of the rainfall on these two dates were drawn to the same scale
as the filtration curve.  (See Table 25 for the comparison of the derived
overflow vo-ume versus measured overflow volume)  The three rainfalls of
May  17 were considered as new rainfalls and separate mass curves drawn
for each one.

An analysis of the results in Table 25  indicates that there is a great
?eal of variation  in the overflow volumes for the two storms.  On
May  17, 30 percent to 60 percent of the rainfall on the  impervious areas
ran off.  However, the same  infiltration curve applied to the rainfall
of June 13 yielded a volume of runoff from the pervious area greater
than the total runoff measured.  Both storms were approximately one-year
storms.  Comparisons were made for the other two districts and similar
inconsistencies were noted.  Therefore, on the basis of this analysis,
the standard residential infiltration curve was not applicable.

3.  Modified Hydrograph Method

A relationship between peak overflow rate and rainfall was derived from
the measured data.  Three graphs were plotted for each overflow.  These
were the maximum 10, 20, and 30 minute  rainfall  intensities versus the
peak overflow rates which they produced.  The intensities of rainfalls
with durations  less than the stated times were averaged over the time
period.  Compound  rainfalls and overflow hydrographs were separated.

A straight  line relationship was found  between maximum rainfall  intensity
for a given duration and peak overflow  rate.  The  least amount of devia-
tion was produced  by a rainfall of 20 minute duration.   (See Figures 52,
53, and 54)  All three graphs distinguish between antecedent rainfall and
no antecedent rainfall conditions.  This distinction disappears, however,
at higher  intensity rainfalls for Numbers 8 and  17 sewer districts.  All
                                  83

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                               TABLE 25


                   OVERFLOW VOLUME - NO.  17 OVERFLOW
                  Using  Standard  Infiltration Curve
May 17, 1969

1.
2.
•*

Rainfa
Runoff
Inches
Runn-f -f

II, total
, Pervious
depth on
PA r vinu«;

- Inches
Area* -
pervious area
Area - £
1
0.27
0
0
2
0.44
0.14
32
3
1 .16
0.28
24
June 13
1969
1 .20
0.38
32
4.  Runoff, Pervious Area  -
    Inches depth on drainage district   0        0.09    0.19     0.25


5.  Overflow, Measured by  weir -
    Inches depth on drainage district   0.05     0.14    0.40     0.10


6.  Runoff, Impervious Area  -
    Inches depth on drainage district   0.05     0.05    0.21     0


7.  Runoff, Impervious Area  -
    Inches depth on impervious area     0.15     0.15    U.to     u


8.  Runoff, Impervious Area  - %
56       34      54      0
* Standard  Infiltration - Capacity Curves for Pervious Surface,
  Residential areas (standard curve), Design and Construction of

  Sanitary  and Storm Sewers, ASCE MOEP No. 37.
                                  84

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three graphs start at or near the origin for antecedent rainfall condi-
tions.  For no antecedent rainfall conditions, overflow starts when the
20 minute rainfall exceeds the values given in Table 19.  Following are
the mathematical formulas for the relationships shown on the three
graphs:

Maximum Twenty Minute Rainfall versus Peak Overflow Rate

     Q  =  Peak flow, cfs

     I  =  Maximum average 20 minute rainfall  intensity, In./Hr.

No. 8 Overflow

      I)  No Antecedent Rainfall

         1^ 0.39,  Q  =  18  (I - 0.12)

         I> 0.39,  Same as with Antecedent Rainfall

     2)  Rainfall within 24 hours

         J£ 0.75,  Q  =  \2(l)

         I> 0.75,  Q  =  20  (I - 0.30)

No. 17 Overflow

      I)  No Antecedent Rainfall

         I£ 0.39,  Q  =  I 10  (I - 0.18)

         I> 0.39,  Same as with Antecedent Rainfall

     2)  Rainfall within 24 hours

                    Q  =  60  (I - 0.03)

No. 23 Overflow

      I)  No Antecedent Rainfall

                    Q  =  33  (I - 0.15)

     2)  Rainfall within 24 hours

                    Q  =  40 (l)
                                  85

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The maximum ten minute rainfall  intensity cannot be used to describe a
20 minute duration rainfall hydrograph.   If the unit hydrographs for an
overflow are graphically summed, the resulting hydrograph  is the S
curve.5  Assume each unit  hydrograph is for a five minute duration unit
storm.  Since the rainfall  intensity remains constant, the four hydro-
graphs for the 20 minute duration  rainfall will have the same maximum
ten minute rainfall  intensity  as the ten minute duration rainfall with
only two hydrographs.  The peaks for the two rainfalls are obviously
di fferent.

The maximum 20 minute  intensity  can be used to describe a ten minute
rainfall, however.   Assuming the two hydrographs from the ten minute
rainfall have the same volume  as for the  four hydrographs  from the 20
minute rainfall, the composite peak for the four hydrographs would be
only a  little  less than the composite  peak for the two hydrographs.

A 30 minute  rainfall duration  produces more deviation than a 20 minute
rainfall duration because  of the nature of the rainfalls measured.  Only
one high  intensity  rainfall lasted longer than 20 minutes  and still pro-
duced only one  hydrograph  peak.  The remaining high  intensity rainfalls
 lasting  longer  than  20 minutes produced multiple peaks because of the
 irregularity  of  their  intensities.

The peak overflow  rates  shown  in Figures  Numbers 52,  53, and 54  are
 limited by the  maximum sewer capacities.   With the  control  structures,
these are equal  to  50, 70, and 65  cfs  for Numbers  8,  17, and 23  overflows,
 respectively.   The  data  plotted  for Number 17  overflow  in  Figure  53
clearly shows the  limiting effect of the  sewer capacities.

The volumes  of  overflow  were  related to rainfall  by means  of the  unit
hydrograph.   Since  the peaks  of  the unit  hydrographs  are directly pro-
portional to their  volume, there was also a  straight line relationship
between the  rainfall and overflow volumes.   These  relationships  were
expressed as  the following mathematical  formulas:

Twenty  M_j_nute Rainfall  versus  Overflow Volume

      0  =  Overflow  Volume, Depth on sewer district in  inches

      P  =   RainfalI, inches

No. 8 Overflow

      I)  No  Antecedent Rainfall

         P£: 0.13,   0  =  0.18 (P - 0.04)

         P >  0.13,   same as with Antecedent  Rainfall
                                   86

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     2)  Rainfall  within 24 hours

         P£ 0.25,  0  =  0.12 P

         P > 0.25,  0  =  0.20 (P - 0.10)

No.  17 Ove r fIow

     I)  No Antecedent Rainfall

         P^ 0.13,  0  =  0.51 (P - 0.06)

         P > 0.13,  same as with Antecedent Rainfall

     2)  Rainfall  within 24 hours

                    0  =  0.28 (P - 0.01)

No.  23 Overflow

     I)  No Antecedent Rainfall

                    0  =  0.20 (P - 0.05)

     2)  Rainfall  within 24 hours

                    0  =  0.25 P

These formulas were used to determine the overflow hydrographs for the
one-year, two-year, and five-year frequency twenty-minute storms.   (See
Figures 55, 56, and 57)
                                 87

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                             SECTION XVI

                     RIVER RESPONSE TO RAINFALL
An analysis was made of the discharge records for the Sandusky River
above and below Bucyrus to determine the relationship between rainfall
and runoff for Bucyrus and the upstream drainage basin.  The records
used for this analysis covered the time period from February 4, 1969,
to September 24, 1969.  The rainfalls were segregated into 24 hour time
intervals.  The average rainfall for the entire drainage basin was
obtained by averaging the rainfall from the three rain gages.  All hydro-
graphs were separated from the base river flow.

All of the storms passing over Bucyrus move in an Easterly direction.
Since the upstream drainage basin is east of Bucyrus, the storms will
pass over Bucyrus before any rain falls in the upstream drainage basin.
This phenomena produces two distinct runoff hydrographs at the downstream
gage, first the urban runoff hydrograph, and then the upstream drainage
basin runoff hydrograph.

Urban Runoff Hydrograph

The urban runoff hydrograph includes the runoff from:  the sewered area
in the combined sewer overflows; the non-sewered drainage areas between
the two stream gages which flows directly to the river; and the area
adjacent to the river for one or two miles above the upstream gage.  The
percent of the urban hydrograph from combined sewer overflow varied con-
siderably but was generally about one-half the volume of the urban run-
off hydrograph.  The volume of runoff from the area adjacent to the
river above the upstream gage also varies greatly.  The peak flow rates
measured at the upstream gage varied from four cfs to 267 cfs for rain-
falls greater than 1,00 inch.   This runoff peaks at the upstream gage
1.5 hours after the rainfall has stopped in Bucyrus and becomes part of
the total urban hydrograph.

Figure 63 is the distribution graph for the urban runoff from a unit
storm in Bucyrus.  The significant runoff reaches the downstream gage
approximately one hour after the start of the rain.  The river peaks two
hours later.  In seven hours the river returns to its pre-storm flow.
The maximum hydrograph peak observed during the study period was 332 cfs
on July II.   On this date, approximately one-half of this peak was from
the upstream drainage area.

Upstream Drainage Basin Runoff Hydrograph

Following the urban runoff hydrograph the river returns to its pre-storm
flow until the hydrograph from the upstream drainage basin arrives.  The
time of arrival  depends entirely on the velocity in the river.  The lag
                                  89

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time of the peak flow following the end of the rain varies from 40 hours
to 17 hours for river flows of four to 300 cfs at the upstream gage.
For flows greater than 500 cfs the lag time will  be approximately 16
hours.  The travel time between the upstream and downstream gages also
varies with the velocity.  The peak will take an additional 6.5 hours to
travel to the downstream gage at  10 cfs, 1.5 hours at 500 cfs, and one
hour at 2000 cfs.

The hydrograph for the upstream drainage basin is a much flatter hydro-
graph than the urban runoff hydrograph.  The minimum time between start
of hydrograph and peak is five hours.  The peak of the hydrograph varies
with the season of the year and the  length of time since the preceding
rai nfal I .

The relationship between rainfall and runoff for the study period of
February through May was entirely different from the relationship for
June through September.  For February through May, there was a straight
line relation between rainfall and peak flow for rainfalls greater than
0.75  inch and peak flows greater than 500 cfs.  During this period
normally any rainfall greater than 1.5  inches will produce a peak river
flow greater than  1500 cfs.

Most of  the storms measured from June through September were short,
intense  thunderstorms.  The rainfall intensities for these types of
storms  varied greatly between rain gages.  The peak flows for the up-
stream  drainage basin hydrographs also varied greatly for amounts of
rainfall.  For example, a  1.2 inch rainfall produced no peak flow on
June  13  and 500 cfs peak flow on  July 20.  The minimum peak and maximum
peak flows possible from a  1.5  inch  rainfall are 25 cfs and 700 cfs,
respectively.
                                  90

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                             StiCTION XVI I

             EVALUATION AND CORRELATION OF WASTELOAD DATA
Waste Loads versus Overt lows

The strength and amount of waste load discharged from combined sewer
overflows depends on a number of factors, including duration and inten-
sity of rainfall, volume of runoff, number of days between overflow
events, efficiency of street cleaning operation, and design character-
istics of the sewer system.  This portion of the report will evaluate
the effect of rainfall, runoff and number of days between overflows on
the strength and amount of waste load discharged to the river.

The relationships between BOD, total solids, suspended solids, chlorides,
phosphates, the  nitrogen series, and length of overflow for the three
selected sewer districts have been graphed and are shown  in Figures 23
throuqh 43.  The E»D and suspended solids concentration generally reach
a peak about 20  minutes after start of overflow and then  tend to drop
at a fairly rapid rate  for two to three  hours and then approach a  lower
limit.  Samples  taken approximately  12 hours after start  of overflow
indicate that the BOD and  suspended solids concentration  will decrease
to about  15 mg/l and 50 mg/I, respectively.

Generally, the  longer the  period of time between overflows  the  larger the
waste  load for a particular  overflow volume.  The  influence of  this
parameter  is shown  by comparing  the BOD  waste  load of  the June  13 and
August 9 overflow events.  Table  16 shows that  the June  13  overflow
volume was 480,000  cubic  feet and  the BOD  load  was  1063  pounds, while
the Auaust 9 event  overflow  volume was 398,000  cubic  feet with  a BOD
 load of 2310 pounds.  The  rainfall on June  13 was  1.20 inches with  a
peak  intensity of 2.77  inches per  hour while the  rainfall  on  August 9
was only  0.56  inch  with a  peak  intensity of  2.28  inches  per hour.   There
was a  period of  five  days  of  dry weather preceding the June 13  overflow
event  and  twelve days of  dry  weather preceding  August 9.

Waste  Loads  versus  Rainfall

 Figure 58  and  Figure  59 show the apparent relationship between  the  BOD
 and  suspended  solids  discharged  fron the three  combined  sewer districts
 sampled  and  total  rainfall  per  storm.  These figures  have been  plotted
 using  the  data  from the five complete overflow  events sampled during
 the  study  period.   These  relationships have  been  developed from five
 overflow  occurrences  and  do not consider many  other  factors that may
 influence the  waste loads from  combined  sewer  overflows.   However,  the
 graphs definitely indicate a trend.

 In addition  to the  relationship between  rainfall  and  BOD, the number  of
 days  of dry weather preceding overflow  has  been incorporated  into  the
                                   91

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rainfall-BOD and rainfall-suspended solids relationships and Is shown on
Figures 58 and 59.  The number of days between rainfall  appears to have
a greater influence on the BOD than on the suspended solids.

Effect of Overflows on River Water Quality

One of the major objectives of this study is to determine what effect
the combined sewer overflows have upon the water quality of the Sandusky
River.  Samples were taken at selected locations upstream,  intown, and
downstream during dry and wet weather along with visual  observations of
the condition of the river before, during and after overflows.  Also, an
aquatic biology survey of the river, which is presented elsewhere in the
report, was made to determine the overflow effects on life  forms  in the
river.

Table  17  very clearly shows the pollutional effects of the  combined
sewer  overflows on the quality of the Sandusky River.  The  BOD concen-
tration at the  first bridge downstream (3/4 mile below treatment  plant)
 is more than  doubled by the overflows and the suspended solids have
quadrupled while the total coliform count has increased ten-fold.  The
August 9  overflow event increased the BOD concentration at  the first
bridge downstream, from II mg/l with a river flow of nine cfs to  51 mg/l
with  a flow of  130 cfs.  This  is a BOD rate increase from 530 pounds per
day  before overflow, which is equal to the effluent  load from the treat-
ment  plant, to  35,500 pounds per day during overflow.

 Figure 46 presents a typical dissolved oxygen profile of the  river during
 times of  low  flow  (10 cfs or  less).  Normally, due to the wastewater
treatment plant's effluent, the  dissolved oxygen of  the river below the
wastewater  treatment  plant  is  extremely  low for about five  to seven
 miles before  the  river  starts  to recover.

 Figure 47 compares  dissolved  oxygen  profiles of the  river during  wet and
 dry  weather.   The graph shows  that the combined sewer overflows tend to
 lengthen  time of  recovery  for the river.

The  assimilation  capacity  of  a river is  defined  in  this report as the  BOD
waste load  that the  river is  capable of  treating  by  self-purification
processes and not depress  the dissolved  oxygen  concentration  of the  river
below 4 mg/l.   Laboratory  analyses and  waste  load  calculations of
selected  river samples  have  shown that  the assimilation capacity  of  the
 Sandusky  River at Bucyrus  is  approximately 25 pounds of BOD per  day  per
cfs  at low  flow (less than 10 cfs).   This is a population equivalent of
 150  per cfs.   The calculations and analyses also indicate that the
 assimilation  capacity of  the  river increases with flow and temperature.

The  quantity  of nitrate nitrogen discharged into the river from  combined
 sewer overflows and  the wastewater treatment plant effluent is negligible
 compared  to the amount  of  nitrate nitrogen contributed to the river from
 rural  runoff.   The  annual  nitrate nitrogen load discharged to the river
                                  92

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by overflows is about 12,200 pounds as N03 based on an annual  overflow
volume of approximately 365 million gallons and an average NO, concen-
tration of 4.0 mg/l.  The wastewater treatment plant contributes about
3,500 pounds per year based on a flow of 2.2 MGD and NO^ of 0.5 mg/l.
This gives a total of 15,700 pounds of N03 per year.  In contrast,  on
April 19, 1969, approximately 136,000 pounds of nitrate nitrogen (N03>
passed the upstream gage and on May 19, 1969, approximately 192,000
pounds of NO, passed the upstream gage.  These  large amounts occurred
during times of high river flow in the spring and early summer.

The amount of total phosphates discharged into the river by combined
sewer overflows and the wastewater treatment plant effluent is signific-
ant when compared to the total phosphates contributed by rural runoff.
The wastewater treatment plant effluent discharges into the river about
160,000 pounds of PO. per year while the combined sewer overflows dis-
charge about 30,000 pounds of P04 per year.  The phosphates from the
overflows are based on an annual overflow volume of 365 million gallons
and an average PO. concentration of  10.0 mg/l.

On April  19,  1969, approximately 5,600 pounds of P04 passed the upstream
gage and on May  19,  1969, about 34,600 pounds of P04 came off the up-
stream drainage area.  Assuming an average  PO^  concentration  of 0.7 mg/l
and using the average  river  flow of  80 cfs  there  is about  110,000 pounds
of PO. passing the  upstream  gage per year.

Therefore,  the wastewater treatment  plant effluent  discharges about 50
percent of  the total phosphates  in the  river while  the  combined sewer
overflows contribute about  10  percent of the total  phosphates.
                                  93

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                             SECTION XVI I I

                       GENERAL DESIGN CONDITIONS
Certain basic design conditions must be established before any alternate
solutions can be evaluated for the combined sewer system.  These condi-
tions include the stream water quality which must be protected; the
design storms that result in waste discharges from which the stream must
be protected; the design storms corresponding overflow volume, peak
rates of overflow and the average maximum waste loads.

The stream water quality for the Sandusky River, downstream from Bucyrus
was established by the Ohio Water Pollution Control Board as (I) Minimum
Conditions Applicable to All Waters At All Places and At All Times and
(2) Aquatic Life "A", which have the following criteria:

                 (I) MINIMUM CONDITIONS APPLICABLE TO
               ALL WATERS AT ALL PLACES AND AT ALL TIMES

I.   Free from substances attributable to municipal, industrial or other
     discharge that will settle to form putrescent or otherwise objec-
     tionable sludge deposits;

2.   Free from floating debris, oil, scum and other floating materials
     attributable to municipal, industrial or other discharges in amounts
     sufficient to be unsightly or deleterious;

3.   Free from materials attributable to municipal, industrial, or other
     discharges producing color, odor or other conditions in such degree
     as to create a nuisance;

4.   Free from substances attributable to municipal, industrial or other
     discharges in concentrations or combinations which are toxic or
     harmful to human, animal or aquatic life.

                         (2) AQUATIC LIFE "A"

The following criteria are for evaluation of conditions for the main-
tenance of a well  balanced warm-water fish population at any point in
the stream except for areas immediately adjacent to outfalls.   In such
areas cognizance will be given to opportunities for the admixture of
effluents with stream water:

I.   Dissolved oxygen:  Not less than 5.0 mg/l during at least 16 hours
     of any 24-hour period, nor less than 3.0 mg/l  at any time;

2.   pH:  No values below 5.0 nor above 9.0 and daily average  (or median)
     values preferably between 6.5 and 8.5;
                                  95

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3.   Temperature:  Uot to exceed 93  F. at any time during the months of
     May through November, and not to exceed 73  F. at any time during
     the months of December through April;

4.   Toxic substances:  Not to exceed one-tenth of the 48-hour median
     tolerance  limit, except that other limiting concentrations may be
     used in specific cases when justified on the basis of available
     evidence and approved by the appropriate regulatory agency.

Since the Sandusky River through Bucyrus  is available for body contact
use and fishing, some consideration should be given to recreational uses
which require,  according to the Ohio Water Pollution Control  Board the
follow!ng:

                     WATERS FOR RECREATIONAL USES

The following criterion  is for evaluation of conditions at any point in
waters designed to be used for recreational purposes, including such
water-contact activities as swimming and water skiing:

     Bacteria:   Coliform group not to exceed 1,000 per 100 ml as a
     monthly average value (either MPN or MF count); nor exceed this
     number  in  more than 20 percent of the samples examined during any
     month;  nor exceed 2,400 per  100 ml (MPN or MF count) on any day.

Design Storms

After consideration of the general conditions which prevail during
various rainfall patterns, two design storms were selected — a two-year,
one-hour  storm  for the peak overflow rate, a one-year, 24-hour storm for
the total volume of overflow.  The one-hour storm  is the spring, summer
and fall  type of thunderstorm, with very  high  intensities and short
duration.  The  amount and  intensity of  rainfall during thunderstorms
varies greatly  over the  drainage  basin.   The one-year, 24-hour storm
resembles a  more generalized  rainfall.  The  intensities will not vary
greatly during  the 24 hours and over the  drainage basin.  Both types of
storms are most likely to occur during  the summer months of June, July,
August, and  September.   (See Table 26)

Protecting the  river from the peak overflows of a  two-year, one-hour
frequency rainfall is a  logical choice  since this  rate of flow  is the
maximum capacity of most of the trunk  sewers of the  combined sewer
system.  Also very few thunderstorms will  last longer than one hour and
any additional  rainfall  after one hour  will  not add  significant peak
flow.

The probability of the two-year,  one-hour storm occurring  is the greatest
during the summer months when the flow  in the  river  is  the  lowest.  Dilu-
tion water is usually not available from  the  upstream drainage basin
during an overflow from this type of storm.
                                  96

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The volume of overflow from the one-year, 24-hour frequency rainfall  was
selected, in addition to the peak rate of overflow from the two-year,
one-hour storm, so that the river would be completely protected from
pollution due to combined sewer overflows for a return period of one
year.

Peak Rate of Overflow

The rainfall for a two-year, one-hour storm was read from the intensity
duration curves at twenty minute intervals.  (See Figure 15)  The
estimated total rainfall equals  1.23 inches.  The three 20-minute rain-
falls were arranged to correspond to the storm pattern given  In the ASCE
Sewer Design Manual,2 which the  peak intensity occurs at three-eighths
of the total storm time.  This was approximated by placing the second
highest  intensity rainfall  in the first twenty minutes of the storm,
with the highest  intensity  and  lowest  intensity  intervals following.

The peak flows  for Numbers  8,  17, and  23 sewer districts were computed,
using the relationships  developed  in the modified hydrograph  method
section.  A  hydrograph  for  each  overflow was derived  for each of the
20-minute rainfalls.  No antecedent  rainfall conditions were  assumed.
Each hydrograph was  then lagged  behind the start  of  its corresponding
rain by  the  amount given in Table  19.   The sum of all  three  hydrographs
for each overflow equaled the  hydrograph  for the  total storm.   (See
Figures  60,  61, and  62)

A review of  the composite hydrographs  in  Figure  61  and 62  showed that
the  peak overflow  rates for Numbers  17 and 23 overflows were  limited by
the  maximum capacities  of their sewer  systems.   Therefore  revised  hydro-
graphs were drawn  for these two overflows. These hydrographs have the
same  runoff  volume  as the original hydrographs.   The peak  of  the hydro-
graph was  assumed  delayed until  the  sewer had  sufficient capacity.   The
shape of the hydrograph was defined  by assuming  the hydrograph  had the
same recession curve as the original  hydrograph,  only delayed by the
 volume of  the peak.

 Since Numbers 8,  17, and 23 sewer districts were the only  districts for
 which unit hydrographs had been determined, the  following  assumptions
 were made for the remaining 21 districts:

  I.   All hydrographs have the basic  shape of a triangle.

 2.   The hydrograph begins ten minutes after the start of  the rainfall.

 3.   The peak occurs five minutes following the end of the significant
      rainfall or 45 minutes after start of rainfall.

  4.   The hydrograph will end at a time equal to the time of concentra-
      tion following the end of  the rainfall.
                                   97

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5.   The total  runoff volumes are equal  to the following percentages of
     rainfal I:

                    Semi -developed           2Q%
                    Suburban-Residential     25%
                    Residential               30?
                    Commercial
These assumptions are based on the characteristics of the hydrographs
for Numbers 8, 17, and 23 sewer districts.  The runoff percentages are
based on the classification system given in Table 7.

The peak overflow rates and overflow volumes for a two-year, one-hour
storm were computed for the remaining 21 sewer districts using
the above assumptions.  (See Table 27)  The peak overflow rates of 13
out of the 24 sewer districts were limited by the maximum sewer capac-
ities, and the peak rates of two additional districts were equal to the
maximum sewer capacities.  The hydrographs for these districts were
adjusted by assuming the hydrographs had the same recession curves as
the original hydrographs, only delayed by the volumes of the peaks.

Volume of Overflow

For the one-year, 24-hour storm, it was not necessary to plot a hydro-
graph for each twenty minutes of rainfall for Numbers 8, 17, and 23
sewer districts.   Instead the following runoff percentages were assigned
the three districts:

          Number  8 Sewer District      20%
          Number  17 Sewer District      28%
          Number  23 Sewer District      25$

These runoff  percentages are  based on the  runoff  formulas developed by
the "Modified Hydrograph Method".

The runoff  percentages given  in assumption five under Peak Rate of Over-
flows were  used to compute  the runoff from the one-year, 24-hour storm
for the remaining districts.  The volumes of runoff obtained for these
districts and Numbers 8, 17,  and 23 sewer districts are given  in Table
28.  A one-year,  24-hour storm has a total rainfall depth of 2.3 inches.
Antecedent  rainfall conditions were assumed.

Design Waste  Loads

The waste  loads discharged  from the two design storms,  previously  pre-
sented, have  been calculated  for two different conditions, the  average
and the maximum.
                                  98

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                 TABLE  26

     PROBABILITY  OF  THE DESIGN  STORMS
    2  Year,  I  Hour  Storm
I  Year,  24 Hour  Storm
Month
January
February
March
Apr! 1
May
June
July
August
September
October
November
December
*Reference:
Probability Order
of Occurring of
%* Magnitude
0
0.5
1
1
2
9
15
13
7
1
0.5
0
50
Rainfal 1
1 1
9
8
6
5
3
1
2
4
7
10
12
Frequency Atlas of
Probabi 1 i ty
of Occurring
%*
5
4
1 1
8
8
1 1
15
12
8
7
6
5
100
the United States,
Order
of
Magnitude
1 1
12
4
7
6
3
1
2
5
8
9
10

Technical Paper No.  40, U.  S. Department of
Agriculture, pages 59-61.
                     99

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                                TABLE  27
                       OVERFLOW PEAKS  AND VOLUMES
                                 FOR THE
                          2 YEAR,  I  HOUR STORM

                              Overflow Volume
   Sewer
District No.

     I
     2
     3
     4
     5
     6
     7
     8
     9
    10
    II
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24

    TOTAL
%
Rainfal Is
20
30
30
30
40
30
40
*
30
40
50
30
35
30
35
40
#
25
30
25
25
25
*
20
Depth
Inches
0.25
0.37
0.37
0.37
0.48
0.37
0.48
0.20
0.37
0.48
0.62
0.37
0.43
0.37
0.43
0.48
0.33
0.31
0.37
0.31
0.31
0.31
0.29
0.25
1000
c.f.
65
3
26
151
57
28
6
131
4
13
14
56
14
94
17
9
544
6
33
14
9
81
397
18
                     Overflow
                       Peak
                       cfs

                        23+
                          I
                          5+
                        42+
                        21
                          4+
                          1 +
                        49
                          2
                          5
                          5
                          7+
                          3+
                        29+
                          6
                          3+
                        140+
                          2
                          6+
                          5
                          3
                         12+
                        70+
                          7
       1,790

=  13.4 Ml 11 ion Gal Ions
* Overflow volume computed using formulas found on page 86.
+ Peak adjusted to Maximum Sewer Capacity
                                  100

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   Sewer
District No.

     I
     2
     3
     4
     5
     6
     7
     8
     9
     10
     I I
     12
     13
     14
     15
     16
     17
     18
     19
     20
     21
     22
     23
     24

     TOTAL
                               TABLE 28

                           OVERFLOW VOLUMES
                                FOR THE
                           YEAR, 24 HOUR STORM
 41
 10.8
  5.0
452.5
  5
 24
 12
.7
.5
.1
.8
  7
 72.4
377.8
 20.7
                                            Overflow Volume
i
Rainfal Is
20
30
30
30
40
30
40
20
30
40
50
30
35
30
35
40
28
25
30
25
25
25
25
20
Depth
Inches
0.46
0.69
0.69
0.69
0.92
0.69
0.92
0.46
0.69
0.92
1.15
0.69
0.80
0.69
0.80
0.92
0.64
0.58
0.69
0.58
0.58
0.58
0.58
0.46
1000
c.f .
122
6
49
282
107
53
II
299
8
24
26
105
26
176
31
17
1,050
12
61
25
16
152
794
35
                                       3,487

                         = 26 MI I lion Gal Ions
                                   101

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The average waste loads for the design storms have been calculated using
the average BOD and suspended solids concentrations of all  of the over-
flow samples analyzed and as summarized in Table 15.  The average BOD is
125 mg/l and the average suspended solids is 480 mg/I.  These concentra-
tions apply to the first flush out which occurs in approximately two to
three hours after start of overflow.  BOD and suspended solids concen-
trations of 20 mg/l and 150 mg/l, respectively, are used as averages for
overflow volumes that occur after three hours duration.

The average BOD and suspended solids waste  loads for the two-year, one-
hour design storm, which has an overflow volume of  13.4 million gallons
from all 24 sewer districts, are 14,000 pounds and 53,500 pounds,
respectively.  For the one-year, 24-hour design storm, which has an
overflow volume of 26 million gallons from  all 24 sewer districts, the
BOD load is  14,000 pounds and the suspended solids  load is 62,500 pounds.

The maximum waste  loads that could be expected from the two design storms
have been determined from envelope curves that were developed from the
results of the BOD and suspended solids data.  These envelope curves,
shown on Figures 23 through 28,  indicate the maximum BOD and suspended
solids concentrations versus time after start of overflow that could be
expected.  The amount of BOD and suspended  solids discharged from each
of the three selected sewer districts is determined by superimposing the
developed envelope curves over the design storm hydrographs and matching
flows with concentrations.

The computed maximum waste  loads for the two-year, one-hour design storm
are as  follows:

                                                        Pounds of
     Sewer District           Pounds of  BOD            Suspended Sol ids

         No.   8                   1,500                     10,600

         No.  17                  6,200                    30,000

         No. 23                  3,700                     17,500

The above waste  loads give  an  average BOD of  1,100  pounds per  100 acres
and suspended  solids of 5,800  pounds  per  100 acres.   Expanding this to
include the entire sewered  area  of  Bucyrus  gives a  design BOD waste  load
of  18,000 pounds and a suspended solids load of 90,000 pounds.

The maximum waste  loads for the  one-year, 24-hour design storm were com-
puted by essentially the same  procedure.  The maximum  BOD expected  is
17,100  pounds  and  the maximum  suspended solids expected  is 76,000 pounds.

Table 29 presents  a summary of the  average  and maximum waste  loads  for
the design storms.
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                               TABLE 29

                     DESIGN STORMS AND WASTE LOADS


                           Overflow
                  Total     Volume          BOD          Suspended Solids
                Rainfall   Million    	Ibs.	   	Ibs.
Design Storms    Inches    Gal Ions    Average  Maximum   Average  Maximum

2-yr.,  I  hr.     1.23        13.4     14,000    18,000    53,500   90,000

l-yr., 24 hr.     2.3        26       14,000    17,100    68,000   76,000
                                   103

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                              SECTION XIX

                          ALTERNATE SOLUTIONS
This section of the report will present various methods of abatement
and/or control of the pollution from combined sewer overflows.  The
degree of protection, advantages and disadvantages along with the
estimated costs are presented for each method.

A.  Complete Separation of Sanitary Wastewater and Storm Water

Complete separation of sanitary wastewater and storm water has histor-
ically been prime solution for pollution due to combined sewer systems.
However, there are disadvantages as well as advantages of complete
separation as presented below.

               (I)  Advantages of Separate Sewer Systems

Separation of sanitary wastewater from storm water permits complete
treatment of all sanitary wastewater before being discharged into the
receiving stream.   The wastewater treatment plant facilities are required
to process only the dry weather flow.  Elimination of storm water from
the treatment plant will enable the plant to operate at a higher
efficiency.

Many of the bacteria and other organisms responsible for intestinal and
other diseases are found in sanitary wastewater.  The separate sewer
system delivers the sanitary wastewater to the treatment plant where
these organisms can be controlled.

The separation of the sanitary wastewater from the storm water will elim-
inate basement flooding during times when the combined sewers are inade-
quate to carry the storm runoff.

             (2)  Disadvantages of Separate Sewer Systems

Many cities such as Washington, D.C., New York, Philadelphia, Detroit,
Milwaukee, Minneapolis and Chicago have found, through engineering studies,
that complete separation is usually not economically feasible.  The cost
estimates for separation of the Bucyrus sewer system, presented in this
section of the report, show that the cost is indeed very high.

In addition to the high cost, there are other disadvantages of separation.
Sewer separation only partially reduces the pollutional  effects from
combined sewer overflows.  Recent studies, including this report, have
shown that storm water runoff from urban areas contains a significant
amount of contaminates harmful to stream water quality.   The degree of
pollution of storm water varies from that of very dilute sewage to strong
sewage.
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There is also an extreme inconvenience factor to the populace involved
when converting to a separate system.  Streets are torn up for years,
utility  services are disrupted periodically, traffic rerouted, etc.
The complete separation of the individual house services, roof drainage
lines and basement drain tile is almost  impossible.

                      (3)  Cost of Sewer Separation

Separation of combined sewer systems can be accomplished in two ways.
One, the existing combined sewer system can be used as a storm sewer and
a new sanitary sewer system constructed.  Two, the existing sewer system
can be used as a sanitary sewer and a new storm sewer system constructed.
Both of these systems have been investigated and cost estimates prepared.

Constructing a new sanitary system involves paralleling the existing
sewer system with sewer pipe sized for sanitary wastewater only.  The new
sewer would be a few feet deeper than the existing sewer so that the
house laterals could be connected to the new pipe.  A cross section of
the system  is shown  in Figure 64.  This  system would include about
208,000 feet of eight inch and ten inch  pipe and about  14,000 feet of
trunk sewer.  Also,  about 3,700 house  laterals would have to be dis-
connected from the existing sewer system and re la id to discharge into
the new sanitary sewer.  The existing  interceptor sewer, paralleling the
Sandusky River, would be used to convey  the sanitary wastewater to the
wastewater  treatment plant.  The existing connector pipes between the
 interceptor and the  existing sewer system would be plugged so that the
storm water runoff  would go  directly to  the  river at the various over-
 flows.

The estimated  cost  for  a  new sanitary  system is $9,300,000.00.

 Since the  existing  combined  sewer system is  designed to handle  a one-in-
two year  storm, the construction  of  a  new  storm sewer  system would  con-
sist of  paralleling the existing  system with approximately the  same  size
pipe as the existing pipe.   The new  pipe would  be at a more  shallow
depth since the existing  sewer was constructed  deep enough to catch
sanitary wastewater. All of  the  existing  storm inlets would be discon-
nected  from the existing sewer and connected to the  new storm  sewer.
Also, on some  of the larger  lines  there will  be house  services  that
would be cut and these  would  have  to be re I a id  to the  existing  sewer.
A  cross section of  this  method  is  shown in Figure 64.

The trunk  lines of  the  new storm  water system would  discharge  directly
 into the  river.  The sanitary  wastewater would  be carried  by the exist-
 ing sewer  system and interceptor  to  the treatment plant.

The estimated  cost  for  the new storm water system is  $8,800,000.00.
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B.  Interceptor Sewer and Lagoon System

This method of abating pollution from combined sewer overflows proposes
construction of an interceptor sewer to collect the large overflow
volumes, and an aerated  lagoon system to treat the waste loads from the
overflows.  A pump station is required to pump the overflows to the
lagoon system.  (See Figures 65 and 66)

                    (I)  Gravity Interceptor Sewer

The proposed gravity interceptor sewer would parallel  the existing inter-
ceptor along the Sandusky River and would terminate near the present
junction manhole with the existing northwest trunk sewer.

The primary concern in the design of the interceptor was determining the
peak capacity the pipe must handle at every point in the system.  This
required routing each of the design storms overflow hydrographs down the
interceptor and determining their time base relationship to each other.
A graphical addition of  the hydrographs was used to determine which
combination gave the highest peak value at each section of the  inter-
ceptor.  Each section of pipe was designed for the maximum peak flow.
The following  pipe sizes and peak flows were obtained:

                                Pipe  Sizes               Peak Flow
    Location                       inches                    cfs

Below  #1 Overflow                  36                       23

Below  #8 Overflow                  72                       150

Below #17 Overflow                  108                      348

Below #23 Overflow                  120                      435

From this analysis  it was found that  there were 39 minutes of travel
time between  Numbers  I and 24 overflows.  Due to  the  longer travel times
in  Numbers  17 and 23 trunk sewers, which delays the peaks, all  three
overflow  peaks coincide.  Number 8 overflow takes eleven minutes  to
travel  to Number  17 overflow, and an  additional nine  minutes to travel
to  Number 23  overflow.   The peak rate of flow  in  the  interceptor  below
Number  23 overflow was equal to 435 cfs, of which 60  percent was  from
the three major overflows.

               (2)  Interceptor Sewer Using Holding Tanks

This  is a modification of the proposed gravity  interceptor presented
above  in  item (I)  in which the  size of  the  interceptor is reduced by
using  holding tanks  located at  Numbers 8,  17,  and 23  overflows.   These
tanks  were  designed  to  intercept the  top one-half of  the peak  flows  and
release them  at an even  rate.   The  volumes of  the three  tanks  were com-
                                   107

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puted by determining the volumes in the top one-half of the hydrographs
for the overflows below the preceding tank, and are equal  to I.I, 1.9,
and 1.4 million gallons for Numbers 8, 17, and 23 overflows, respec-
tively.

Completely enclosed, concrete tanks were used for the cost estimate.
The tanks are fifteen feet deep, of which the top ten feet is a surge
tank, operating by gravity, and the bottom five feet is pumped.

The interceptor for this method was designed by the same methods used for
the gravity interceptor system.  The following pipe sizes and flows were
obta i ned:

                                 Pipe Sizes               Peak Flow
     Location                      i nches                    cfs

Below  #1 Overflow                   36                       23

Below  #8 Overflow                   60                       76

Below #17 Overflow                   84                      186

Below #23 Overflow                   96                      235

                            (3) Pump Station

A 215 MGD  (333 cfs) pump station with a  1.0 million gallon wet well is
proposed.  The storage volume of the proposed gravity  interceptor sewer
is also required during the design storm peak flow of 435 cfs.

The capacity of the pump station for the  interceptor sewer using holding
tanks would be 150 MGD with a 0.5 million  gallon wet well.

                           (4) Aerated Lagoon

A system of aerated and non-aerated  lagoons is proposed as a method of
treatment for the combined sewer overflow  wastewaters.  The proposed
facilities could also be utilized as tertiary treatment for the effluent
from the existing city activated sludge treatment plant.  The  lagoon
system would consist of structures of earthen embankments to form a
retention basin with several  sections, as  shown in Figures 65 and 66.
This facility would be similar in construction to existing reservoirs
which are used throughout northwest Ohio to store water for municipal
water supply.  However, using this type of facility for wastewater
retention and treatment would require consideration of need for changing
water levels, installation of mechanical aerators and removal of accumu-
lated solids.  The design requirements to  prevent pollution of the stream
are discussed in preceding sections of the report.
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The design of the system will  provide for biological  oxidation of the
combined sewer overflows and would provide for continued biological
oxidation of the effluent from the sewage treatment plant.  Three main
design parameters are of importance.  These are:  detention time, the
biological oxidation rate (designated as the "k" rate of the wastewaters
being treated) and, the air supply.  However, the "k" rate essentially
establishes the requirements of both the detention time and the air
supply.

The rate of reaction constant of the degradation of organic matter,
commonly called the "k" rate, varies with the type of organic matter and
the state of oxidation which exists  in the wastewater, at the time treat-
ment  is begun.  The "k" rate for the raw wastewater is greatest and will
decrease with advance stages of treatment.  The "k" rate  for normal
domestic wastes, as received in a wastewater treatment plant,  is usually
about O.I.  However,  it may vary from half this value to  several times
this  value.  The "k"  rate found by  Havens & Emerson of combined sewer
overflows was approximately O.I.  The "k" rate  for activated sludge
effluents,  as found by  Havens  and  Emerson, was  0.03l.y   In a study of
the effluents from extended aeration plants bv  the Ohio  Department of
Health, the "k"  rates were  found  to be  O.OI3.10  In the  Ohio Health
Department  study,  the flows were  found  to be  about 25  percent  of design,
so the  detention times  were on the order of  four  days.

The  "k" rate  also  affects the  quantity  of wastewater  that may  be dis-
charged into a  given  stream.   A wastewater with a high "k" rate will  have
a greater effect on  a stream than a wastewater with  a  lower 'k  rate.
Just  as a rapid  stream  will  assimilate  more wastewater than a slow stream
 (with ponding),  a  given stream will assimilate a  higher ultimate BOD load
as the "k" rate becomes less.   Assimilation of wastewater of  BOD load is
 used  here to mean  that  the  dissolved oxygen will  not  be depressed  below
 a desi red level.

 The  determination  of  the possible variations of the  "k" rate of combined
 sewer overflows or treated  overflows is beyond the scope of this study.
 Also the variation of "k" rate in partially treated  overflow wastewaters
 or the possible increase in assimilation capacity of a given stream as
 the "k" rate decreases with increased degrees of treatment is beyond the
 scope of this study.

 From data obtained during this study the range of permissible BOD loading
 has been determined.   The dissolved oxygen in the Sandusky River below
 Bucyrus will be maintained at the  desired level of four mg/l   if the BOD
 wastewater  load does not exceed 25  pounds per day per cfs of stream flow.
 This Is equivalent to the waste load of a population of  150 persons.

 The  rainfall-runoff pattern results in an average of about 1.0 MGD of
 wastewater, with  an average BOD of  125 mg/l and a maximum expected BOD
 of 170 mg/l.  The BOD  load will be  treated or  controlled by two methods.
 One  is by  settling and biological  oxidation.   Part of the BOD wi I I be
                                    109

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removed by settling and, In this design, has been assumed to be 50 per-
cent.  Biological oxidation of the BOD will follow under aerobic condi-
tions  using mechanical aerators.

A "k"  rate of 0.10 has been assumed for the first stage treatment or
first  five days of detention and a "k" rate of 0.05 for the remaining
15 days of detention.  The percent of BOD  remaining after a given number
of days will be according to the equation:  % =  IOO-(l-IO~kt) |QO (when
k = O.I or 0.05 and t = number of days).   The degree of treatment of the
wastewater from combined sewer overflows  in the  lagoon system is esti-
mated  to exceed 95 percent after 20 days.

A second method of controlling BOD will be to discharge partially treated
wastewater to the stream.  During some periods of rainfall when enough
rainfall has occurred to fill the lagoon,  the stream flow will also have
increased.  When prolonged rainfall occurs such as a one-year, 24-hour
storm  of 2.3 inches, the quantity of urban runoff will be sufficient to
fill the proposed lagoon.  However, as a  result of such a rainfall the
stream flow will increase due to upstream  drainage runoff.  Without
tertiary treatment for the wastewater treatment effluent only when the
upstream runoff exceeds 20 cfs can an additional BOD  load be discharged
at the rate of 25 pounds per day per cfs.  The wastewater collected may
be discharged from the  lagoon after partial treatment to increased
stream flow.

If tertiary treatment  is provided for the  wastewater treatment plant
effluent then either this effluent or the  treated combined sewer over-
flow may be discharged to the stream at any flow.

The average runoff from the urban area of  Bucyrus is about 1.0 MGD.  The
lagoon size must allow  for a variation  in  the peak distribution.  A
lagoon designed for an average detention  time of 20 days or 20 million
gallons and in addition a volume equal to  the two-year, one-hour storm
will provide the required variation.  This requires a volume of 33
million gallons.  This will protect the stream from any overflows of any
storm  less than the two-year, one-hour storm.  This protection does not
require any dilution from the upstream drainage area.  This volume is
about  27 percent greater than that required for the runoff from a one-
year,  24-hour storm.

A detailed analysis of the past ten-year precipitation records for the
four critical  months — July, August, September, and October — show
that the average monthly rainfall plus the rainfall from the two-year,
one-hour storm is greater than the one year maximum monthly rainfall.
The records also show that a total  monthly rainfall equal to the average
monthly rainfall  plus the rainfall  from a  one-year, 24-hour storm would
occur only once in eight years.   Therefore, a lagoon with a storage
volume of 33 million gallons will protect the stream from the two design
storms and from the one-year maximum monthly rainfall.
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The proposed lagoon will provide for greater protection of the stream if
the available dilution water from the upstream drainage area is used.
Storms of longer than 24-hour duration, or when rainfall is such that
the runoff from the urban area is greater than the average of one MGD
plus the two-year, one-hour storm, will produce upstream runoff.  One
example of this was a storm on September 16-17, 1969, during which 2.3
inches fell  in 19 hours.  This resulted in a peak upstream flow of 100
cfs and a total stream volume of 65 million gallons over a three-day
period.  In this case about 3,000 pounds of BOD could have been released
to the stream with no detrimental effects.  With a BOD concentration of
approximately 75 mg/l or less (having received minimum one-day treat-
ment) at least five million gallons of partially treated overflow could
have been discharged with the higher stream flows.   In actual operation,
the BOD may be as  low as 50 mg/l which would allow discharging about 7.5
million gallons of partially treated wastes.

A detailed mass diagarm of the past ten years record of stream flow and
rainfall was plotted to determine the required  lagoon size using the
assimilation capacity of the upstream dilution water in conjunction with
the treatment capability of the  lagoon.  The analysis indicated that a
22 million gallon  lagoon will protect the stream  from pollution by com-
bined sewer overflows  if the treatment capacity of the  upstream dilu-
tion water is used.

At the present time, there  is very  little factual  information available
verifying assumed  treatment efficiencies.  Therefore, until  it  is
demonstrated that  the  smaller lagoon plus the upstream  dilution water
will provide the  necessary protection, the  larger 33 million gallon
storage volume is  recommended.

The  lagoon may be  located across the river from the existing wastewater
treatment plant.   Four  cells are proposed, each one  257 feet by 458  feet
from centerline of berm to centerline of berm, and cover an area of  15
acres.  The  total  depth  is 22 feet, of which the  top four  feet  is free-
board and the bottom five feet  is permanent pool.  The  earth embankment
has 2  1/2:1  side  slope  and a ten-feet wide berm.  Ten and one-half feet
of the  lagoon are  below the original ground level.

The  lagoon has a  total  storage capacity of 37.75  million gallons.  The
permanent pool would allow approximately three days  detention time to
provide tertiary  treatment for the existing wastewater  treatment plant
effluent.  The lagoon  dimensions were based on the minimum amount of
earth embankment  per volume.

Accumulation of solids  in the lagoon are estimated to be about two per-
cent per year.  The  removal of the accumulated  solids will be required
every  five to eight years to maintain an overall  efficiency of system
of 90  percent.

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The cost estimates of the interceptor sewer and lagoon system are as
follows:

     Gravity  Interceptor, Pump Station and Aerated Lagoon

     I.  Gravity  Interceptor                         $3,600,000

     2.  Pump Station                                 1,000,000

     3.  Aerated Lagoon                                 620,000

                                      TOTAL COST     $5,220,000

     Holding Tanks on System, Gravity Interceptor, Pump Station, and
     Aerated Lagoon

     I.  Holding Tanks                               $1,500,000

     2.  Gravity  Interceptor                          3,000,000

     3.  Pump Station                                   800,000

     4.  Aerated Lagoon                                 560,000

                                      TOTAL COST     $5,860,000

C.  Stream Flow Augmentation

Flow augmentation, as used  in this report, is a method of controlling
pollution from combined  sewer overflows by providing sufficient dilution
water  from storage impoundments to maintain a desired concentration of
dissolved oxygen downstream during overflows of wastewater from the com-
bined  sewers.  This method of control includes an upground storage reser-
voir,  a low head dam to  capture the flow of water in the river, a pump
station to deliver river water to the reservoir, a discharge channel to
release stored water to  river, and a system of rain gages, river flow
indicators and controls to release the required amount of dilution water
into the river.  When wastewater overflows occur, sufficient dilution
water must be released from the reservoir so that the combined assimila-
tion capacity of the dilution water and the river flow can maintain a
desired level of dissolved oxygen.

The volume of stored dilution water required at Bucyrus is 4,500 million
gallons.  The reservoir would have an average depth of 30 feet, which
includes four feet of freeboard and a two-foot conservation pool.  The
area required for the reservoir is about 480 acres.  See Figure 67 for
schematic and typical section of flow augmentation facilities.  The
volume of stored dilution water was based on an average combined sewer
overflow volume of 380 million gallons per year or approximately 1.0
million gallons per day.  The combined sewer overflow has an average BOD
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concentration of  125 mg/l which amounts to approximately  1,000 pounds of
BOD per day.  The water quality data on the Sandusky River, downstream
from Bucyrus, Indicates that the river's assimilation capacity at low
flows (less than  10 cfs)  Is approximate 25 pounds of BOD  per day per cfs.
Using this value  for the  river's waste load assimilation  capacity, the
amount of dilution water  required, in addition to the probable river
flow, was calculated.  The probable river flows were taken from the flow
duration figures  presented in Table 2.

The pump station  capacity, based on the flow duration curves, is 45 MGD
or 70 cfs.

The preliminary cost estimate for this method of treatment Is
$5,000,000.00.

The effectiveness of this method of treating combined sewer overflows
depends upon the  ability of the system to deliver the dilution water at
the time of the overflows.  The urban area's response to  rainfall is
almost immediate  with an average time of 15 minutes from  start of rain
to start of overflow.  This means that the dilution water must reach the
overflow points immediately after start of rainfall.

The nearest site  for a 4,500 million gallon reservoir (about one mile
square) at Bucyrus Is  located about five miles upstream,  adjacent to the
existing water supply reservoirs.  The dilution water from this  location
would have an average travel time to the overflow points  of approximately
five hours.  To deliver the required amount of dilution water to the
overflow, in time to be effective, the dilution water would have to be
released from the reservoir about five hours before start of rainfall.
Obviously trying  to determine the start of rainfall five  hours before It
occurs Is impractical and, in most cases, impossible.  Therefore, flow
augmentation as a method of treating combined sewer overflows is not
feasible at Bucyrus.

D.  Primary Treatment of Overflows

This method of controlling stream pollution from combined sewer overflows
proposes providing primary treatment for the overflows.   Primary treat-
ment would include a gravity interceptor sewer to collect the overflows,
grit chamber, settling tanks, chlorination facilities, anaerobic digester
and sludge drying beds.

The primary treatment facilities have a design capacity  capable of pro-
viding 1.5 hours of detention time for the two-year, one-hour design
storm which discharges 13.4 million gallons of overflow  In two hours.
Five parallel settling tanks are proposed to provide for the variation
in overflow volumes received.
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Each tank Is 70 feet x 250 feet by 20 feet deep.  A chlorination contact
tank 70 feet x 100 feet by 10 feet deep would follow each settling tank.
An anaerobic digester is proposed to treat about 1,500 pounds per day of
volatile suspended solids.  The proposed sludge drying beds have an area
of approximately 7,500 square feet.

Primary treatment of the overflows could be expected to remove 50 percent
to 70 percent of the BOD and suspended solids waste load from the com-
bined sewer overflows.  Chlorination of the overflows would significantly
reduce the bacteria discharge to the stream.

The cost for primary treatment of the overflows is estimated to be
$8,810,000.00.

E.  Chlorination of Overflows

Chlorination of overflows is proposed as a method for controlling the
large number of bacteria discharged to the stream by combined sewer over-
flows.  The literature survey has  indicated that proper chlorination of
the overflows will reduce the peak after-growth of coliforms in the
stream to 10 percent to 30 percent of the coliforms that would develop
if unchlorinated overflows were discharged to the stream.

The proposed chlorination facilities include three chlorine contact tanks
located at Numbers 8, 17, and 23 overflow outlets adjacent to the
Sandusky River, new  interceptor sewers that would collect the overflows
from the various overflow points and deliver the overflows to the con-
tact tanks and chlorination  facilities capable  of providing a chlorine
dosage of up to 40 mg/l.  The size of the proposed contact tanks at
Numbers 8,  17, and 23 overflows are  1.6 million gallons,  1.9 million
gallons and 0.7 million gallons,  respectively.

The estimated cost for chlorination of the  overflows  is $3,000,000.00.

F.  Off-Stream Treatment

The basic alternate  plan of  pollution abatement from combined sewer over-
flows as presented and described herein proposes to intercept and treat
the flow from 24 overflow points  in Bucyrus thereby eliminating all dis-
charges to the Sandusky River up to the design  storms.  This .provides
maximum protection to the Sandusky River  both "in City" and downstream.
Such protection is the equivalent of collecting and treating the waste
water and the discharge from a storm sewer  system  in a community with
separate sewer systems.

The cost of such complete abatement plans should not be related to the
cost of physical separation  without regard  for  the pollutional  load
created by separate  storm sewer discharges.
                                   14

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Pollution abatement from combined sewers may be separated into two
general categories:  (I)  Inner-City and Downstream Pollution Abatement,
and (2) Downstream Pollution Abatement.  The basic approach in this
study has been Inner-City and Downstream Abatement.  Should only down-
stream protection be considered at this time as the first phase of an
overall pollution abatement plan, a considerable reduction in cost
would result.

The same or a pumping station similar to that proposed to pump the flow
from the interceptor sewer could be used to divert the flow in the
Sandusky River to the lagoons for treatment during periods of combined
sewer overflow.  The same pump capacity as that proposed for the inter-
ceptor sewer without holding tanks (333 cfs) would be capable of
diverting the entire river flow which occurs about 95 percent of the
time.  Pumping would only be accomplished during overflow periods and
release from the  lagoon would be accomplished during these pumping
periods to satisfy the  riparian owners water rights.

This concept of downstream water quality protection would not enhance
the water quality  in the river reach within the City, but  it would
result in a cost  reduction of about $3,500,000 on the basic alternate
plan of pollution  abatement and about  $7,000,000 on the cost of physical
separation of the  sewer systems.  At some future date, the  interceptor
sewer could be constructed to collect  the overflows and convey them to
the pumping station and inner-city protection would be realized.

The reduction  in  initial cost would appear to justify that the downstream
protection aspect  be thoroughly evaluated by a demonstration  project.
The demonstration  project should  include monies for reducing or con-
trolling the channel degradation within the city due to the combined
sewer overflows.   Channel projects could  include regrading, reshaping or
paving to reduce  pools  and  low velocity areas where solids would other-
wise tend to settle and become septic.

The estimated  cost of the pumping station,  lagoons and  low head dam  in
the Sandusky River is $1,700,000.
                                   I 15

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                                TABLE 30

                        SUMMARY OF COST ESTIMATES
                                   FOR
                           ALTERNATE SOLUTIONS
A.  Complete Separation of Sanitary Wastewater and Storm Water

    (I)  New Sanitary System                                  $9,300,000

    (2)  New Storm Water System                               $8,800,000

B.  Interceptor Sewer and Lagoon System

    (I)  Gravity Interceptor, Pump Station and Aerated
         Lagoon

              Gravity  Interceptor          $3,600,000

              Pump Station                   1,000,000

              Aerated  Lagoon                  620,000

                            TOTAL COST                        $5,220,000

    (2)  Holding Tanks, Gravity  Interceptor, Pump
         Station and Aerated  Lagoon

              Holding  Tanks                $1,500,000

              Gravity  Interceptor            3,000,000

              Pump Station                    800,000

              Aerated  Lagoon                  560,000

                            TOTAL COST                        $5,860,000

C.  Stream  Flow Augmentation                                  $5,000,000

D.  Primary Treatment  of  Overflows                            $8,810,000

E.  Chlorination of Overflows                                $3,000,000

F.  Off-Stream Treatment                                      $1,700,000
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                              SECTION XX

     PROCEDURES FOR EVALUATING SIMILAR SYSTEMS IN OTHER COMMUNITIES


The studies and data collection accomplished at Bucyrus and described
herein are typical of the engineering effort necessary to develop
evaluation studies and feasible solutions to pollution abatement from
combined sewers.  Each community's needs and methods of abatement are
dependent on growth patterns, topography, capability of existing sewer
system, receiving stream, availability of land, degree of protection
requi red, etc.

Since complete  separation of storm and sanitary sewers  is presently an
accepted method of correcting overflows  from combined sewers, the total
conversion of  combined sewers to either  storm or sanitary systems  if
present storm  sewer  capacity  is  inadequate  may be the most feasible
solution.  Only a detailed  analysis  of the  present combined system with
current design storm conditions  and  future  growth considered will pro-
vide  the answer as to whether  all or portions of the  system should
remain combined.

After the  present combined  sewer system has been  analyzed  and  decisions
made  as to whether all  or portions  of the combined  sewers  are  to remain
as combined  systems the  points of combined  sewer overflow  will  have  been
determi ned.

The local  conditions must be studied and one or  more of the  following
steps considered  and evaluated:

 I.  Intercept the overflow at each  overflow point by a gravity sewer or
     pumping station and force main  for conveyance to point of  treatment,
     or
 2   Construct holding tanks to level out the peak flow from the combined
     sewer and convey same by gravity sewer or pump station and force
     main to point of treatment, or

 3   Discharge settled effluent from holding tank into receiving stream
     if studies have shown that stream can assimilate such waste loads
     and comply with minimum water quality standards, or

 4.  Build treatment facilities designed to protect the minimum water
     quality  in the stream for all overflow requiring treatment.

 The following discussion outlines the procedures, using the results of
 the Bucyrus  data, that  can be used  to determine  and evaluate the above
 mentioned  items.  The decree to  which the Bucyrus data and solutions can
 be applied to another community  is  directly  related to the similarity of
 that  community to Bucyrus.
                                   I 17

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Five basic questions must be answered:  one, the peak rate of overflow;
two, the total volume of overflow; three, the total  waste load discharged
from the combined sewers; four, what can be discharged into the receiving
water; and five, what is the best method of collecting and treating the
waste that cannot be discharged directly into the receiving water.  The
design storms and return frequencies must be selected with consideration
of the five questions.

Analyze Existing Sewer System

The total sewered area must be divided  into sewer districts and a detailed
analysis made of each district including the trunk sewers.  A detailed
analysts must also be made on the overflow structures and interceptor
sewer.

Often the original design notes or an existing  sewer map can be used to
determine the size, grade, and location of the  existing combined  sewers.
A  field check should  be  made to  insure  that no  additional overflows have
been  installed  or drainage areas  added  to the sewer system.  Spot checks
should be made  in each drainage district to determine the type of land
use.  Field work necessary would  depend on  available  information.  The
time  of concentration must also be determined from the sewer travel time
and time  of over-1 and flow.

Select  Design Storm and  Return Frequencies

The capacity  of the existing system  must be given consideration  in^the
 selection of  the design storm, since it controls or  limits  the maximum
overflow rate possible  from the  sewers.  The stream  water quality desired
 and the tolerance of pollution must also be considered  along with the
minimum stream flows which may exist during periods  of  overflow.   In
many communities like Bucyrus, Ohio, there is essentially no stream flow
 available a large percentage of  the time.

All states have established minimum stream standards for stream  water.
The State of  Ohio has five classifications for streams  which are based
on the  water  usage.   The volume  of waste that can  be discharged  into
the receiving water will depend  on how much the stream or lake can
 assimilate without deleterious effects or violating the stream^standards.
This amount can be determined by using one of the  stream purification
 forumulas.   However, in most cases in areas similar to northwestern Ohio
 a waste load  of about 25 pounds  of BOD per day per cfs of stream flow  at
 low flow conditions  is  the maximum permissible  loading.

 Protecting a stream or  lake against every frequency of rainfall   is
 uneconomical.  There will be a design frequency for which an increase in
 the degree of protection cannot be justified.  A two-year frequency rain-
 fall Is suggested for the design of any overflow collection or inter-
 ception system and a one-year frequency rainfall for design of the volume
 of any treatment facilities.
                                    118

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The peak, volume, and quality of the combined sewer overflows are
directly related to intensity and duration of the rainfalls.  If a
recording rain gage has not been located in the area, the total  rain-
fall for various frequencies and durations can be obtained from the
Rainfall Frequency Atlas of the United States, Technical Paper No. 40,
U. S. Department of Agriculture.  For the design of an overflow col-
lection or interception system, a rainfall duration equal to or greater
than the maximum time of concentration should be used.  A minimum dura-
tion of one hour is suggested.

For treatment facilities with long detention times, such as a lagoon,
the total volume will be directly related to the volume of rainfall
expected during the detention period.  One method of obtaining this
volume of rainfall is to take a number of years of rainfall records for
the area, determine the maximum rainfalls for the given detention time,
(20 day period) rank time according to their order of magnitude, assign
frequencies of occurrence, and then select the rainfall corresponding
to the design frequency.  A simpler but  less accurate method of obtain-
ing this rainfall  is to use the total monthly rainfalls.  The monthly
rainfall for the design frequency can then be reduced to the detention
time of the treatment facility by determining the maximum rainfall that
fell in the design month and within the  detention time.

Determine the Runoff From Design Storms

For any combined sewer system with multiple overflows,  a complete sewer
hydrograph is needed for each trunk sewer.  Many cities may not be able
to measure their major overflows to determine a unit hydrograph.  There-
fore, some assumptions for hydrograph shape must be made.

If a hydrograph method Is already being  used successfully for design  in
the city, it should also be used to determine the hydrographs at the
combined sewer overflows.  If not, either the Chicago Hydrograph Method,
as described in the ASCE Sewer Design Manual, or the Modified Hydrograph
Method, as described in this report,  is  recommended for .design.

The Chicago Hydrograph Method may be  used since the Chicago terrain and
rainfall patterns are representative  of  a typical midwestern city.  A
set of curves is given for the peak rate of runoff per  acre drained for
various depression storages and ground slopes.  To determine the total
hydrograph shape, mass curves for lateral outflow from  uniformly developed
areas must be constructed.  This requires a detailed analysis of the
drainage characteristics of the sewer districts and the hydraulics of the
sewer system.

A more simplified method of obtaining a  complete runoff hydrograph  is the
Modified Hydrograph Method developed  in  this report.  The assumptions and
procedure are found under "General Design Conditions".  The time of the
start of overflow and the hydrograph  shape were assumed based on the
characteristics of the hydrographs for Number 8,  17, and 23 sewer
                                  I 19

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districts.  The total  volume of runoff for each district was then com-
puted using the runoff percentages and land use classifications developed
earlier.  These volumes of runoff were used to determine the peak of the
hydrograph through the assumed hydrograph shape.  For most of the sewer
districts in Bucyrus,  this peak exceeded the maximum sewer capacities.

A variation of the Modified Hydrograph Method  is to use the rational
formula for determining the peak of the runoff and through the assumed
hydrograph shape determine the volume of runoff.  This variation might be
more accurate than that used for Bucyrus if coefficients for the rational
formula are well defined for the area and the  times of concentration do
not exceed the  length of significant rainfall.   It should not be used if
the peak  rate of runoff exceeds the maximum sewer capacities of many of
the sewer districts.

Determine Waste Loads from Design Storms

The characteristics of the waste from the combined sewer overflows^of any
city similar to Bucyrus will no doubt be similar to that found during
this study.  Both the BOD and  suspended solids concentration reached a
peak during the first hour of  overflow and then decreased.  Both reach
a minimum concentration after  several hours.   For design purposes,  an
average BOD concentration of  125 mg/l and an average suspended solids
concentration  of 480 mg/l were assumed for the first three  hours of
overflow.  Overflow after three hours will have  an average  BOD and  sus-
pended  solids  concentration of about 20 mg/l and  150 mg/l,  respectively.

The  waste loads discharged during overflows minus  the waste load which may
be  discharged  to  the  stream,  equal  the  volume  of  flow  and waste load which
must be collected  and  treated.

Method  of Collection  and  Treatment

At  Bucyrus  a  gravity  interceptor  was  found  to  be the most economical
method  of collecting  the  combined  sewer  overflows and  carrying the  waste
to  a common  point  for  treatment.   A major pump station is required  at
Bucyrus.   A  detailed  analysis  should  be  made of the  pipe  sizes,  grades,
and  locations  to  determine  if  there are  any  ways to  minimize the cost.
For  example,  if flow  through  the treatment  facilities  can be accomplished
by  gravity  then the pump  station may  be  eliminated.  Another possibility
 is  splitting  the  flow  into  more  than  one  treatment  facility and  locating
the  facilities closer  to  the  overflow  points.   For  Bucyrus, the  pump
station capacity  was  reduced  by  one-fourth  by  using  storage capacity  of
the  gravity  interceptor and the  wet well  to  store the  peak  flow.

The  capacity  of the  interceptor  must  be  equal  to the peak rate of  runoff
 from a  two-year frequency rainfall  minus  the rate of runoff that the
 river can assimilate.   For  example, the  median flow  in the  river at
 Bucyrus during the summer months  is approximately five cfs. The assimila-
 tion capacity of  the  river  at this low  flow  is negligible and  the
                                   120

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interceptor was designed to handle all  of the peak rate of flow from a
two-year frequency storm.  If some of the overflow wastes can be dis-
charged into the stream, a check must be made of the travel times in
the stream between overflow points.  If the duration of overflow is
greater than the travel times between overflows, the rates of^overflow
discharged into the stream must be reduced so that their sum is equal
to the assimilation capacity of the stream.

Based on the analysis made for Bucyrus, the aerated  lagoon is believed
to be the most economical method of treating combined sewer overflows.
A  lagoon can provide the high degree of treatment necessary for the
highly variable flows with a minimum of operation.

The volume of  the  lagoon must be equal to  the volume of  runoff  from  the
one-year frequency 20-day  rainfall minus the volume  the  river can
assimilate.  One method of operation  is to discharge lagoon effluent^
continuously  into  the  stream at  a  constant rate the  stream can  assimi-
 late  during  low  flow.   The lagoon  volume will then equal  the volume  of
 runoff  from the  one-year frequency,  20-day rainfall  minus the volume
 discharged  into  the stream during  this 20-day period.  The other method
 of operation  is  to discharge into the  stream from the  lagoon at a  rate
 determined  by  the  flow in the  stream.   The total volume  discharged during
 the  20-day  period  will  then be directly proportional to  the  flow in the
 stream.
                                    121

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                              SECTION XXI

                            ACKNOWLEDGMENTS
We wish to acknowledge the assistance and cooperation received from the
City of Bucyrus during the investigation and preparation of this report.
We would especially like to acknowledge the assistance of Bernard C.
Piper, Utilities Director and Gerald E. Staiger, Assistant Utilities
Director.

The aquatic biology survey portion of this report was performed by Mr.
Rendell Rhoades, Chairman of Biology, Ashland College, Ashland, Ohio.

We wish to acknowledge the assistance and cooperation received from Mr.
Harold P. Brooks, Hydrologist, Water Resources Division, Geological
Survey, United States Department of  Interior.

We wish to acknowledge the assistance and cooperation received from Mr.
Howard Kenny, United States Weather  Bureau, Port Columbus, Columbus, Ohio.
                                   123

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                            SECTION XXI I

                             REFERENCES
         - Standard Methods for the Examination of Water and Wastewater,
     12th Edition.  (1965)

2.  ASCE - Design and Construction of Sanitary and Storm Sewers, MOEP
    No. 37 (I960) pg. 31 - 77.

3.  "Basic Information Needs  in Urban Hydrology", A Study by the American
    Society of Civil Engineers (April 1969) pg. 51 and 52.

4.  Fair, G. M., and Geyer, J. C., Elements of Water Supply and Waste -
    Water Disposal, John Wiley & Sons,  Inc., New York (1958) pg. 54.

5.  LInsley, R.  K., Kohler, M. A., and  Paulhus, J. L., Hydrology for
    Engineers, McGraw-Hill Book Company,  Inc., New York  (1958) pg. 212
    and 202.

6.  Hicks, W.  I.,  "A Method of Computing  Urban Runoff",  Proceedings,
    ASCE, Vol.  109  (1944)  pg.  1217.

7.  Tholin, A.  L., and  Keifer, C.  J., "The  Hydrology of  Urban Runoff",
    Journal , Sanitary Division ASCE, Vol. 85, No. SA2,  (March  1959)
     pg. 47 -  106.

8.   Rainfall Frequency  Atlas  of the  United  States, Technical Paper No.
     40, U. S.  Department of Agriculture,  Washington, D.  C.

9.   "Feasibility of a Stabilization  - Retention Basin  in Lake Erie at
     Cleveland,  Ohio", A Report Prepared for the Federal  Water Pollution
     Control Administration under Contract No.  14-12-27  (May  1968)

10.   Haggerty,  L. T., "Two  Methods  for the Evaluation of  Aerobic Digestion
     (Extended  Aeration)  Waste Treatment Plant Effluents", A  Report Pre-
     pared  for  The  Ohio  Department  of Health.
                              REFERENCES
                      FROM THE LITERATURE SURVEY

II.   Anderson,  R.  E.,  "Lake County Adopts Clean Lake  Policy",  Water  and
     Sewage Works  115- 9 - 412 (Sept.,  1968).

12.   Anon., "Characterization, Treatment & Disposal of  Urban Stormwater",
     Intl. Conf. on Water Pollution Research,  Munich, Germany,  (Sept.
     1966)
                                  125

-------
13.   Anon., "Regina Opens Worlds Largest Aerated Municipal  Lagoon",  Water
     and Sewage Works 114- 4 - 80A (Apr.,  1967).

14.   Anon., Water & Sewage Works I 14 - 12 - 5A (Dec.,  1967).

15.   Anon., "Depollutlon Study", Water & Sewage Works  115  - 10 - 480
     (Oct., 1968).

16.   Anon., "Re-using Storm Runoff", Env. Science and  Techn 2  - II  - 1001,
     (Nov., 1968).

17.   AWWA, "Problems of Combined Sewer Facilities and  Overflows",  WPC
     Research  Series WP-20-II, FWPCA (1967).

18.   Benjes, H. H., & others, "Storm - Water Overflows from Combined
     Sewers",  JWPCF 33 - 12 -   (1961)

19.   Benzie, W. J., & Courchaine, R. J., "Discharge from Separate Storm
     Sewers & Combined Sewers", JWPCF 38 - 3 - 410 (Mar.,  1966).

20.   Bernardt, H., "Aeration of Wahnbach Reservoir", JAWWA 59  - 8 - 943
     (1967).

21.   Burm, R. J., and Vaughan, R. D., "Bacteriological Comparison Between
     Combined and Separate Sewer Discharges in Southeastern Michigan",
     JWPCF 38 - 3 - 400  (Mar.,  1966)

22.   Burm, R. J., "The Bacteriological Effect of Combined  Sewer Overflows
     on the Detroit River", JWPCF 39 - 3 - 410 (Mar.,  1967).

23.   Burm, R. J., and others, "Chemical & Physical Comparison  of Combined
     and Separate Sewer Discharges", JWPCF 40 -  I - 112 (Jan., 1968).

24.   Camp, Thomas R., "Chlorination of Mixed Sewage & Storm Water", J.  of
     the San Engr. Piv. , Proc. of the Am. Soc. of Civil Engrs. 87 - I
     (1961 ).

25.   Cliassen, Rolf E., "Coliform Aftergrowths in Chlorinated  Storm Over-
     flows", J. of the San Enqr. Div., Proc. of the ASCE 94 -  371  (1968).

26.   Clift, Mortimore A., "Experience with Pressure Sewerage", J.  of the
     San Enqr. Div., Proc. of the ASCE 9_4 - 849  (1968).

27.   Correspondence With City Engineer, City of Regina (Dec.  3, 1968).

28.   Dunbar, D. D., & Henry, J. G.  F., "Pollution Control  Measures for
     Stormwaters and Combined Sewor Overflows", JWPCF 38 - 9 (1966).

29.   Gifft, H. M., and Symons, George E., "How to Estimate Storm Water
     Quantities", Water & Wastes Enqr. 5 - 46 (Mar.,  1968).
                                 126

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30.  Greeley, Samuel  A.,  & Langdon, Paul  E.,  "Storm Water & Combined
     Sewage Overflows",  J. of the San Enqr.  Div.,  Proc.  of the Am.  Soc.
     of Civil Engins. 87_ - 57 (1961).

31.  Gregory, J. H.,  and others, "Intercepting Sewers and Storm Stand-by
     Tanks at Columbus,  Ohio", ASCE Trans. Paper No. 1887 (Oct., 1933).

32.  Havens & Emerson, "Master Plan for Pollution Abatement, Cleveland,
     Ohio", Vol. I  (1968).

33.  Jensen, L. D., & Renn, C. E., "Use of Tertiary Treated Sewage as
     Industrial Process Water", Water and Sewage Works MJ - 4 ~ I84»
     (Apr.,  1968).

34   Johnson, C. F.,  "Equipment, Methods  and Results from Washington,
     D. C., Combined  Sewer Overflow  Studies", JWPCF 33 - 7 - 721 (July,
     1961).

35.  Kalinske,  A.  A., "Surface  Aerators", Water &  Sewage Works  115- I  -
     33  (Jan.,  1968).

36.  Koelzer, V. A.,  and  Others,  "The Chicago I and  Deep Tunnel  Project",
     41st Annual Conf.  of WPCF  (Sept. 22-7,  1968).

37.  Krenki,  Peter A.,  and others, "Impounding  and Temperature Effect
     on  Wastes  Assimilation", J.  of the  San  Engr.  Div.,  Proc.  ASCE 95_ -
     37  (Feb.,  1969).

38.  Lancashire River Authority,  1st and 2nd Annual  Reports  for the  period
      10/15/64 to 3/31/66  and the  year ending 3/31/67 152 pp.

39.   Laredo, David,  & Bryant, E.  A., "Silt  Removal  from Combined Sewers",
     Water & Sewage  Works 115 - 12 - 561 (Dec.,  1968).

40.   Lothrap, Thomas L.,  & Sproul, Otis  J.,  "High-level  Inactivation of
      Virusis in Wastewater by Chlorination", JWPCF 41  - 4 - 570 (1969).

 41.   Maneval, D. R., "Western European  Waste Water Treatment", Water and
      Sewage Works  114 - 6 - 231 (June  1967).

 42   McDermott, Gerald N., "Management  of Wastewaters from Outside Areas
      of  Industrial Plants", 41st Annual  Conf. of WPCF (Sept. 22-27,  1968).

 43.   McDonald, D.  B., & Schmickle, R.  D., "The Effects of Flood Control
      Reservoir on Water Quality", Water & Sewage Works IJ4 -  II - 411
       (Nov.,  1967).

 44.   Patrick, Ruth,   "Effect of Suspended Solids, Organic Matter and Toxic
      Materials on Aquatic Life in Rivers", Water and Sewage Works 115  -
      2-89  (Feb.,  1968).
                                   127

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45.  Pavia, E. H., & Powell, C. J., "Chlorination & Hypochlorination of
     Polluted Storm Water at New Orleans", 41st Annual  Conf.  of WPCF
     (Sept. 22-27, 1968).

46.  Quase, H., "Report on Underwater Storage in Washington,  D. C.",
     Env. Science and Techn. 2 - 8 - 577 (Aug., 1968).

47.  Rand Development Corp., "Investigation of the Use of Coal  for Treat-
     ment of Sewage and Waste Waters", Office of Coal Research Report
     No. 12, U. S. Dep't. of Interior (1965).

48.  "Results of D. 0. Recorder in River Calder in WhoI ley",  Lancashire
     River Authority, 1st and 2nd Annual for the Period 10/15/64 to
     3/31/66 and the year ending 3/31/67.

49.  Riddick, Thomas M., "Forced Circulation of Large Bodies of Water",
     J. of the San Engr. Dlv., Proc. of the Am. Soc. of Civil Engrs. 84_ -
     1703  (1958).

50.  Simpson, George D., "Treatment of Combined Sewer Overflows & Surface
     Waters at Cleveland, Ohio", 41st Annual Conf. of WPCF,  (Sept. 22-27,
     1968.

51.  Sullivan, Richard  H.,  "Problem of Combined Sewer Facilities and Over-
     flows",  JWPCF 41 -  2-113 (1969).

52.  Sullivan, Richard  H.,  "Problems of Combined Sewer Facilities and
     Overflows",  41st Annual Conference of WPCF  (Sept. 22-27,  1968).

53.  Thtrumurthi,  D., & Nashashlbl, 0.  I., "A New  Approach for Designing
     Waste Stabilization Ponds", Water  &  Sewage Works, Ref.  No. R 208,
      (1967).

54.  USPHS,  "Pollutional  Effects of Stormwater and Overflows from Combined
     Sewer Systems"  USPHS Pub I. No.  1246  (1964).

55.  Waller,  D.  H.,  "One City's Approach  to the Problem of Combined  Sewage
     Overflows",  Water  & Sewage Works  114 -  113  (Mar., 1967).

56.  Weibel,  S.  R.,  and others, "Urban  Land Runoff as a Factor  In Streams
     Pollution",  JWPCF  36 - 7  - 914  (July,  1964).

57.  Weibel,  S.  R.,  & others,  "Pesticides & Other  Contaminants  from Rain-
     fall  &  Runoff as Observed in  Ohio",  JAWWA 58  -  8  -  1075 (Aug.,  1966).

58.  WPCF  -  ASCE,  Design &  Construction of Sanitary  &  Storm  Sewers,  WPCF
     Manual  of Practice No. 9  (1966).

59.  Wright,  Darwin,  "The Causes and  Remedies of Water Pollution  from
     Surface Drainage of Urban Areas",  FWPCA.
                                  128

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SECTION XXIII




   FIGURES

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                                   LAKE     ERIE
                                              •OUTH BASS I.
                                                               /
                                                               I
                                                               V
                                                                   KCLLEY8 I.
                                                                 arblthtod

                                                                  .Cedar Point
                                                                     Sandusky
                                                         STUDY  AREA

                                                      SCALE IN MILES
                                                            10
                                                                          20
1421
 353
980
        LEGEND
    Drainage areas enclosed by shaded

    Drainage areas enclosed by unshaded
    lines ——   ^— (sq. miles)
    Drainage areas above points
90  indicated by arrows - sq. miles
    Approximate  low-water elevation
    in feet above sea  level
                                                     Figure  No.  I
                                                  SANDUSKY RIVER
                                                     Drainage  Area
                                   131

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132

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Average Slope
Population
                                    ^—IOO5

                             Combined Sewer
                                                                                 CONTOUR INTERVAL 5 FEET
                                                                                     SCALE IN FEET
                                                                                          1000
                                                                                                            2000
                                                                                       L
                                                                                              J_
       PHYSICAL  DATA
Sewered  Drainage Area   179 Acres
Non-Sewered Drainage Area 0 Acres
Impervious Area        33.7 Acres
                                                      Overflow ft Weir Location
                         0.85 %
                           2020
       Figure   No. 3

NO.  8   SEWER  DISTRICT

       Bucyrus, Ohio

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Overflow S Weir Location
         PHYSICAL  DATA
 Severed  Drainage Area     452 Acres
 Non-Sewered Drainage  Area  162 Acres
 Impervious  Area         33.7 Acres
 Average  Slope              0.65 %
 Population                    4300
        Figure  No.  4

 NO.  17  SEWER DISTRICT

        Bucyrus , Ohio
CONTOUR INTERVAL 5 FEET
    SCALE  IN FEET
0       1000     2000

I  ....  I  -.  -—I

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          M^—Sondusky
River
            •Overflow  a Weir Location
       PHYSICAL  DATA
Sewered  Drainage  Area   373 Acres
Non-Sewered Drainage Area  0 Acres
Impervious Area        26.1 Acres
Average  Slope             0.25 %
Population                  I960
                          CONTOUR INTERVAL 5 FEET
                              SCALE  IN FEET
                                  1000        2000
       Figure   No. 5

NO.  23   SEWER  DISTRICT

       Bucyrus, Ohio

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 NO. 23 RAIN  GAGE
UPSTREAM  SAMPLER






   Rgure  No. 6




        136

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  NO. 8 DRY WEATHER  WEIR
NO. 17 WEIR DURING OVERFLOW








        Figure  No. 7




            137

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NO. 8 OVERFLOW WEIR
NO. 17 OVERFLOW  WEIR








     Figure  No. 8





         138

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   NO. 8 INSTRUMENT  SHELTER
WASTE WATER  TREATMENT PLANT
     OVERFLOW  RECORDER
        Figure No. 9
             139

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 UPSTREAM GAGE
DOWNSTREAM GAGE
 Figure  No. 10

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RIVER AT NO. 8 , LOW FLOW CONDITIONS
    RIVER  UPSTREAM  FROM  NO. 8
       LOW FLOW  CONDITIONS
            Figure  No. II

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                         Figure  No. 12

             Sandusky  River  Flow at  Bucyrus,0hio

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Comparison  of Monthly Discharge 8  Monthly  Rainfall
         Sandusky  River  at Bucyrus,0hio
                        143

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20
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RAINFALL DURATION - MINUTES
                                            100
                Figure  No. 15
          Intensity - Duration  Curves

              for  Bucyrus , Ohio

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                         Figure   No. 16
                    Rainfall and Overflow
              No. 8  Overflow - March 24,1969

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-------
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                                    195

-------
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-------
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-------
BIBLIOGRAPHIC:

     Sewer Overflows.   FWPCA PubTTcaTfi
                                        i No. OAST-32 r
                                                    eng i neer i ng i nvest i gat i on
                                     i the SandLjsky River at Bucyrus, Ohio and
                                 i the combined sewer ov<
                                                            >ws.  The City of
     2,540 acres, a population of (3,000, and a combined sewer syste
     Pleasured and sampled at 3 locations comprising 64% of the City's sewered
     area and the river flow was measured and sampled above ana below Bucyrus.
     0.05 of an inch will produce an overflow.  The combined sewers will over-
     flow about 73 times each year discharging an estimated annual volume of
     350 million gallons containing 350,000 pounds of BOD and  1,400,000

     BOO of  120 mg/l, suspended solids of 470mg/l, total coliforms of
     11,000,000 per  100 ml and fecal coliforms of  1,600,000 per  100 ml.  The
     BOO concentration of the Sandusky River,  immediately downstream  from
     Bucyrus, varied from an average of 6 mg/l during dry weather to  a high
     of 51 mg/| during overflow discharges.  The suspended solids varied from
     an average of 49 mg/l during dry weather to a high of 960 mg/l during

     400,000 por  100 ml  during dry weather to a high of 8,800,000 per 100 ml
     during overflow discharges.
 BIBLIOGRAPHIC:
      burgess  8  Niple,  Limited.   Stream Pollution  and  Abatement From Combl_ned_
      Sewer Overflows.   FWPCA  Publication No.  DAST-32  November 1969
 ABSTRACT:

      and comprehensivi
      from combined  sei
                   i the results of a detailed engineering investigation

                   overflows on the Sandusky River at Bucyrus, Ohio and
      for pollution abateff-ent from the combined sewer overflows.   The City of

      is tributary to Lake Erie.   Bucyrus has an incorporated area of about
      2,340 acres, a population of 13,000, and a combined sewer system with an
      average dry weather wastewater flow of 2.2 million gallons per day.  A

      ducted on the combined sewer overflows in which the overflows were
      measured and sampled at 3 locations comprising 64* of the City's sewered
      area and the river flow was measured and sampled above and below Bucyrus.

      The results of the study show that any 20 minute rainfall greater than
      0.05 of an Inch will produce an overflow.  The combined sewers will over-
      flow about 75 tiroes each year discharging an estimated annual volume of
      350 million gallons containing 350,000 pounds of OOC and 1,400,000
      pounds of suspended solids.  The combined sewer overflows had an average
      BOO of 120 mg/l, suspended so I ids of 470 mg/l, total coliforms of
      11,000,000 per 100 ml and fecal coliforms of 1,600,000 per 100 ml.  The
      BOO concentration o< the Sandusky River, immediately downstream from
      Liucyrus, varied from an average of 6 mg/l during dry weather to a high
      of 51 mg/l during overflow discharges.  The suspended  solids varied from
      an average of 49 mg/l during dry weather to a high of  960 mg/l during
      overflow discharges.  The total cofiforms varied from  an average of
      400,000 per  100 mi during dry weather to s high of 8,800,000 per  100 ml
      during overflow discharges.
  BIBLIOGRAPHIC:
       Burgess & Niple.  Limited.   Strei
       Sewer Overflows.  FWPCA Pub I lea'
                                i  Pollution  and  Abatement From Combined
                                on No.  DAST-32  November 1969
  ABSTRACT:
       This  report  contains  the  results of  a  detailed  engineering investigation
       and comprehensive  Technical  study to evaluate the pollutionsi  effects
       from  confined  sewer overflows on the Sandusky River at Bucyrus,  Ohio and
       to evaluate  the  benefits,  economics  and feasibility of alterna+e plans
       for pollution  abatement from the combined  sewer overflows.  The  City of
       Bucyrus  is  located near the  upper end  of the Sandusky River Basin which
       is tributary to  Lake  Erie.   Bucyrus  has an incorporated area of  about
       2,340 acres, a population of 13,000, and a combined sewer system with  an
       average  dry  weather wastewater flow  of 2.2 million gallons per day.  A
       year  long detailed sampling  and laboratory analysis program was  con-
       ducted on the  combined sewer overflows In  which the overflows were
       measured and sampled  at 3 locations  comprising  64j of the City's sewered
       area  and the river flow was  measured and sampled above and below Bucyrus.
                                                                         than
                                                                           The
The results of the study show that any 20 minute rainfall 91
0.05 of an inch will  produce an overflow.  The combined sewers will over-
flow about 73 times each year discharging an estimated annual volume of
350 million gallons containing 350,000 pounds of BOD and 1,400,000
pounds of suspended solids.  The combined sewer overflows had an average
BOO of 120 mg/l, suspended solids of 470 mg/l, total coliforms of
11,000,000 per 100 ml and fecal coliforms of 1,600,000 per 100 mt.
BOD concentration of the Sandusky River, immediately downstream from
LJucyrus  varied from an average of 6 mg/l during dry weather to a high
of e>l mg/l during overflow discharges.  The suspended solids varied from
an average of 49 mg/l during dry weather to a high of 960 mg/l during
overflow discharges.  The total coliforms varied from an average of
4CO.OOO per 100 ml during dry weather to a high of 8,800,000 per 100 ml
during overflow discharges.
                                                                                   ACCESSION NO.

                                                                                   KEY WORDS:

                                                                                     Combined Sewers

                                                                                     Ora i nage

                                                                                     Hydrographs

                                                                                     Inf iItration

                                                                                     Interceptor Sewer

                                                                                     Overflows

                                                                                     Runo*f

                                                                                     Stream Flow

                                                                                     Urban Runoff

                                                                                     Vtastewater Analysis
ACCESSION NO.

KEY WORDS:

  Combined Sewers

  Ora i nage

  Hydrographs

  InfIItration

  Interceptor Sewer

  Overflows

  Runoff

  Stream  Flow

  Urban Runoff

  Wastewater Analysis
 ACCESSION NO.

 KEY WORDS:

   Combined Sewers

   Ora i nage

   Hydrographs

   InfiItration

   Interceptor Sewer

   Overflows

   Runoff

   Stream Flow

   Urban Runoff

   Wastewater Analysis

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Various Methods of controlling the pollution from combined i
flows are presented along with their degree of protection, advantages.
disadvantages and estimates of cost.  The awttxxJs presented Include
(l» complete separation. (2) interceptor sewer and lagoon system.
(3) stream flow augmentation. (4) primary treatment,  (5) ehlorlnatlon,
and (6) offstream treatment.  It was concluded that the most economical
Method of providing a high degree of protection to the Sandusky River Is
by collect.ng the combined sewer overflows with a large Interceptor and
using an aerated  lagoon system to treat the waste loads from the over-
flows.

This report was submitted  In fulfil Intent of Contract 14-12-401 between
tne Federal Water Pollution Control Administration and Burgess & NIple.
United.
 Various methods ot controlling the pollution from combined sewer over-
 flows are presented along with their degree of protection, advantages.
 disadvantages and estieates of cost.  The methods presented Include
 (I) complete separation. (2) interceptor sewer and lagoon system,
 (3) stream flow augmentation, (4) primary treatment, (5) chlorlnatlon,
 and <6) offstream treatment.  It was concluded thet the most economical
 method of providing a high degree of protection to the Sandusky River Is
 by collecting the combined sewer overflows with a large Interceptor and
 using an aerated lagoon system to treat the waste toads from the over-
 flows.

 This report was submitted In fulfillment of Contract 14-12-401  between
 the Federal Hater Pollution Control Administration and Burgess i NIple.
 Limited.
 Various methods of controlling the pollution from combined sewer over-
 flows are presented along with their degree of protection, advantages,
 disadvantages and estimates of cost.  The methods presented include
 ft) complete separation,  12) Interceptor sewer and lagoon system,
 (3) stream flow augmentation,  (4) primary treatment,  (5)  chlorlnatlon,
 and (6) offstream treatment.  It was concluded thet the most economical
 method of  providing a  high degree of protection to the Sandusky River is
 by collecting the combined sewer overflows with a  large Interceptor and
 using an aerated lagoon system to treat  the waste  loads from the over-
 flows.

 Thl*  report was submitted  in fulfillment of  Contract  14-12-401  between
 the Federal  Mater follutlon Control  Administration  and  Burgess  & NIple,
 Limited.

-------