EPA-670/2-74-096
December 1974
Environmental Protection Technology Series
CHARACTERIZATION AND TREATMENT OF
URBAN LAND RUNOFF
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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EPA-670/2-74-096
December 1974
CHARACTERIZATION AND TREATMENT OF URBAN LAND RUNOFF
By
Newton V. Colston, Jr.
Civil Engineering Department
North Carolina State University
Raleigh, North Carolina 27607
Project No. 11030 HJP
Program Element No. 1BB034
PROJECT OFFICER
Anthony N. Tafuri
Storm and Combined Sewer Section (Edison, N.J.)
Advanced Waste Treatment Research Laboratory
National Environmental Research Center
Cincinnati, Ohio 45268
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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REVIEW NOTICE
The National Environmental Research Center, Cincinnati, has reviewed
this report and approved its publication. Approval does not signify
that the contents necessarily reflect the views and policies of the
U. S. Environmental Protection Agency, nor does mention of trade names
or commercial products constitute endorsement or recommendation for use.
11
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FOREWORD
Man and his environment must be protected from the adverse effects of
pesticides, radiation, noise and other forms of pollution, and the
unwise management of solid waste. Efforts to protect the environment
require a focus that recognizes the interplay between the components
of our physical environment—air, water, and land. The National
Environmental Research Centers provide this multidisciplinary focus
through programs engaged in
• studies on the effects of environmental contaminants
on man and the biosphere, and
• a search for ways to prevent contamination and to
recycle valuable resources.
The objective of the study described herein was evaluation of the rela-
tive impact of urban life characteristics on water quality management.
It is only by knowing the magnitude of each individual input that the
optimum allocation of limited funds can be established.
A. W. Breidenbach, Ph.D.
Director
National Environmental
Research Center, Cincinnati
111
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ABSTRACT
Urban land runoff from a 1.67 square-mile urban watershed In Durham,
North Carolina, was characterized with respect to annual pollutant
yield. Regression equations were developed to relate pollutant strength
to hydrograph characteristics. Urban land runoff was found to be a
significant source of pollution when compared to the raw municipal waste
generated within the study area. On an annual basis, the urban runoff
yield of COD was equal to 91 percent of the raw sewage yield, the BOD
yield was equal to 67 percent, and the urban runoff suspended solids
yield was 20 times that contained in raw municipal wastes for the same
area. Downstream water quality was judged to be controlled by urban
land runoff 20 percent of the time (i.e., the pounds of COD from urban
land runoff was approximately 4-1/2 times the pounds of COD from raw
sewage).
It is conceivable that critical water quality conditions are not typi-
fied by the 10-year, 7-day low flow, but by the period immediately fol-
lowing low-flow periods when rainfall removes accumulated urban filth
into the receiving watercourse, greatly increasing the pollutant load
while not substantially increasing water quantity. Specific urban land
use did not appear to influence the quality of urban land runoff.
The applicability and effectiveness of plain sedimentation and chemical
coagulation of urban land runoff was evaluated. Plain sedimentation was
found to remove an average of 60 percent of the COD, 77 percent of the
suspended solids, and 53 percent of the turbidity. Cationic polyelectro-
lytes and inorganic coagulants were found to provide significant resid-
ual removal increases over plain sedimentation. Alum was judged the
best coagulant and produced average removals of COD, suspended solids,
and turbidity of 84, 97, and 94 percent, respectively.
The EPA Storm Water Management Model (SWMM) was evaluated with respect
to actual conditions as measured in the field. The model was judged to
predict peak hydrograph flows and total hydrograph volumes with reason-
able accuracy; however, it was not judged effective for predicting
pollutant concentrations.
In urban drainage basins, investments in upgrading secondary municipal
waste treatment plants without concomitant steps to moderate the
adverse effects of urban land runoff are questionable in view of the
apparent relative impact of urban land runoff on receiving water
quality.
This report was submitted in fulfillment of Project Number 11030 HJP by
the North Carolina Water Resources Research Institute under partial
sponsorship of the Office of Research and Development, Environmental
Protection Agency. Work was completed as of September 1, 1973.
iv
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CONTENTS
Page
Abstract iv
List of Figures vii
List of Tables x
Acknowledgments xii
Sections
I Conclusions 1
II Recommendations 5
III Introduction 7
Project Scope and Objectives 8
IV Basin Description and Land Use 10
V Sampling 27
Hydrologic Data 27
Automatic Sampler 27
VI Characterization of Urban Land Runoff 36
Hydrologic Information 36
Individual Storm Characterization 36
Base Flow Characterization 39
Effect of Land Use on Water Quality 39
BOD Difficulties 48
COD Exertion Rate Studies 52
Representative Sampling 55
Pollutant Regression Equations 55
Annual Pollutant Yield 58
Summary 63
VII Chemical-Physical Treatment Studies 65
Introduction 65
Jar Test Procedure 66
Coagulants Evaluated 67
Coagulant Evaluation 68
Coagulant Aid Evaluation 75
Coagulant Selection 75
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Sections Page
Batch Scale Coagulant Evaluation 78
Sludge Characterization 80
Summary 86
VIII Relative Impact of Urban Land Runoff 88
Introduction 88
Comparison with Domestic Waste 88
Relative Impact on Downstream Oxygen Content 90
Study Area Characteristics 90
Problem Formulation 90
Interpretation of Results 96
Summary 99
IX Factors Influencing Stormwater Treatment Economics 101
Introduction 101
Collection 101
Treatment 102
Sludge Disposal 102
Summary 103
X Evaluation of EPA Storm Water Management Model 104
Introduction 104
The SWMM Model 104
Program Blocks 105
General Data Requirements 105
Application to Third Fork Creek Drainage Basin 106
SWMM Verification 108
Evaluation of Predicted Quantities of Runoff 109
Evaluation of Predicted Quality of Runoff 114
Summary 115
XI References 117
XII Glossary 118
XIII Appendix 119
VI
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FIGURES
No. page
1 Third Fork Creek study area location within Durham
city limits and North Carolina 10
2 Drainage pattern of Third Fork Creek within Durham,
N. C. 11
3-17 Typical land use within basin 14-21
18-27 Typical stream bed of Third Fork Creek 21-26
28 Schematic diagram showing location and relative
elevations of USGS gage house and control weir 28
29 Schematic of automatic sampling system 31
30 USGS gage house adjacent to Third Fork Creek 32
31 USGS control weir and staff gage at gaging station 32
32 Box housing submersible pump at sampling station 33
33 Automatic sampler control box 33
34 Stage recorder and digital precipitation recorder
inside USGS gage house 34
35 Plexiglass sampling flume 34
36 Modified vacuum sampler 35
37 Pollutant variations with Q and time for Storm No. 20,
Date 6/20/72 40
38 Pollutant variations with Q and time for Storm No. 20,
Date 6/20/72 41
39 Pollutant variations with Q and time for Storm No. 13,
Date 3/16/72 42,
40 Pollutant variations with Q and time for Storm No. 13,
Date 3/16/72 43
41-42 Typical variations of BOD with dilution 50-51
43 Oxygen exertion curves as determined by BOD and COD
uptake 54
vii
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FIGURES (continued)
No. Page
44-46 Pollutant concentrations in mg/1 for a typical hydro-
graph as predicted by adjusted regression equations 60-62
47 Determination of optimum pH and dosage for alum 69
48 . Optimum pH and dosage determination for Dow's C-32 70
49 Determination of optimum pH and dosage for Dow's A-21 71
50 Schematic of batch coagulation-sedimentation column 79
51-52 Suspended solids removal as a function of detention 81-82
time
53 Suspended solids removal as areal overflow rate for
cationic polyelectrolytes 83
54 Suspended solids removal versus areal overflow rate for
ferric chloride 84
55 Suspended solids removal versus areal overflow rate for
alum with and without coagulant aids 85
56 Watershed selected for oxygen sag studies 91
57 Typical storm for conditions at Third Fork Creek treat-
- ment plant 93
58 Effect of channel shape and flow variation on reaeration
. coefficient 94
59 Effect of channel storage on storm flow downstream 95
60 Effect of stormwater treatment on oxygen sag under
storm conditions 98
61 SWMM map of Third Fork Creek system 107
62-65 Modeled versus recorded hydrographs for USGS main gaging 110-
station with associated hyetographs 112
66-67 Modeled versus recorded hydrographs for Sub-basin N-2
with associated hyetographs 113
68-69 Modeled versus recorded suspended solids concentration 114-
at USGS station and N-2 sub-basin for storm of 6/20/72 115
viii
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FIGURES (continued)
No. Page
70 Modeled versus recorded suspended solids concentrations
for storm of 10/5/72 at USGS station 116
IX
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TABLES
No. page
1 Third Fork Creek Land Use Characterization by
Sub-basins 13
2 Hydrologic Description of Urban Runoff Events Sampled 37
3 Average and Standard Deviation of Organics in Urban
Runoff Events at the Main Gaging Station 38
4 Average and Standard Deviation of Solids in Urban
Runoff Events at the Main Gaging Station 44
5 Average and Standard Deviation of Total Phosphorus,
Kjeldahl Nitrogen, and Fecal Coliforms in Urban
Runoff Events at Main Gaging Station 45
6 Average and Standard Deviation of Metals Concentrations
in Urban Runoff Events at the Main Gaging Station 46
7 Average, Range, and Standard Deviation of Pollutant
Concentrations for all Storm Samples 47
8 Average Base Flow Pollutant Concentration for Sub-basins
and Main Gaging Station 47
9 Average Pollutant Concentrations from Sub-basins During
Storm Flows 48
10
Oxygen Uptake Rates (K-) for Urban Land Runoff 53
11 Comparison of Pollutant Concentrations Adjacent to Waters
Surface with Those Obtained by Automatic Sampler 56
12 Equations Describing Urban Runoff Pollutant Flux Near
Channel Bottom in Pounds Per Minute for Durham, North
Carolina, as a Function of Discharge Rate (CFS) and
Time from Storm Start (TFSS) in Hours 57
13 Regression Equations Predicting Pollutant Concentration
(mg/1) in Urban Land Runoff in a Natural Channel Corrected
to Flow at Mid-depth 59
14 Estimated 1972 Pollutant Yield for Third Fork Creek
Drainage Basin in Pounds/Acre/Year 63
15 Individual Jar Test Results at Optimum pH and Dosage 72
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TABLES (continued)
No. Page
16 Individual Jar Test Results for Coagulant Aids 76
17 Coagulant Ranking on Average Residual Removal Efficiency
of COD, Suspended Solids, and Turbidity 77
18 Characteristics of Chemical Sludges 86
19 Comparison of Raw Municipal Waste and Urban Runoff on an
Annual Basis in Pounds Per Acre Per Year Pollutant Yield 89
20 Total Annual Yield of Pollutants from Municipal and
Urban Runoff Wastes in Pounds/Acre During 1972 89
21 Total Yield of Pollutants During Storm Periods from Urban
Runoff and Raw Municipal Wastes in Lbs/Acre During 1972 90
22 Results of Oxygen-Sag Computations for Study Watershed 97
23 Storm of 6/20/72 as Predicted by SWMM 108
24 Effect of Varying Integration Period and Hyetograph
Interval of Discharges as Predicted in SWMM on the
Storm of 6/20/72 109
25 Comparison of Predicted Peak Flows, Total Gutter Flows,
and Time of Peaks for the Four Storms Modeled 110
26 Comparison of Predicted Peak Flows, Total Gutter Flows
and Time of Peaks for the Storms Modeled at Sub-basin N-2 112
27-62 Appendix - Time Parameters and Analytical Results of 120-
Urban Runoff Events Number 1 through 36 146
63-68 Appendix - Third Fork Creek Base Flow Observations at 147-
USGS Gage House and Sub-basins 152
69-73 Appendix - Time Parameters and Analytical Results of
Urban Runoff Events Monitored at Sub-basin Discharge 153-
Locations 157
XI
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ACKNOWLEDGMENTS
The support of Professor David H. Howells, Director of the Water
Resources Research Institute for the State of North Carolina, is
acknowledged with sincere thanks.
The valuable contribution of Mr. Ernest Lyle Lewis in providing depend-
able and accurate analyses of urban runoff samples is appreciated. The
field assistance of Mr. John Ward, Mr. Russell Radford, and Mr. Mike
Wallis is gratefully acknowledged. Mr. Parviz Samar, who conducted the
evaluation of chemical treatment, contributed significantly to the suc-
cess of the project. The technical assistance and review of Dr. Rooney
Malcom is appreciated.
The support of the project by the Office of Research and Development,
Environmental Protection Agency, and the assistance provided by
Mr. Anthony Tafuri, the Grant Project Officer, and D. Dean Adrian, Ph.D.
is acknowledged with sincere thanks.
xii
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SECTION I
CONCLUSIONS
This project had as its goals the (1) characterization of urban land
runoff in Durham, North Carolina, (2) evaluation of the applicability
of chemical-physical treatment of urban land runoff, (3) evaluation of
the EPA Storm Water Management Model, and (4) determination of that
point beyond which the cost of an increased degree of municipal waste
treatment exceeded the benefits of partial or total treatment of urban
land runoff. Whereas the conclusions and findings of this report are
based on information obtained in Durham, North Carolina, the results
contained herein are believed to represent urban areas of the Piedmont
province on the East Coast.
1. The organic concentration in urban land runoff is approximately
one-half that for typical raw waste whereas the concentrations
of heavy metals and solids are two to fifty times greater in
urban land runoff.
AVERAGE, RANGE, AND STANDARD DEVIATION OF POLLUTANT
CONCENTRATIONS FOR ALL STORM SAMPLES
Pollutant
COD
TOG
Total Solids
Volatile Solids
Total Suspended Solids
Volatile Suspended Solids
Kjeldahl Nitrogen as "N"
Total Phosphorus as "P"
Fecal Coliform (///ml)
Aluminum
Calcium
Cobalt
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Zinc
Alkalinity
Mean
mg/1
170
42
1440
205
1223
122
.96
.82
230
16
4.8
.16
.23
.15
12
.46
10
.67
.15
.36
56
Standard
deviation
135
35
1270
124
1213
100
1.8
1.0
240
8.15
5.6
.11
.10
.09
9.1
.38
4.0
.42
.05
.37
30
Range (mg/l)
Low
20
5.5
194
33
27
5
.1
.2
1
6
1.1
.04
.06
.04
1.3
0.1
3.6
.12
.09
.09
24
High
1042
384
8620
1170
7340
970
11.6
16
2000
35.7
31
.47
.47
.50
58.7
2.86
24
3.2
.29
4.6
124
2. Urban land use variations within the study area were not found
to influence the quality of urban land runoff.
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3. The standard biochemical oxygen demand test (BOD) was not found
to be an appropriate qualitative test for urban land runoff.
This was believed due to inhibitory effects and/or inherent prob-
lems with the standard test. Chemical oxygen demand test (COD)
is believed to be the most consistent measurement of relative
storm strength for three reasons:
a. COD values were reproducible in the lab and were not
affected by particle size and/or inhibitory compounds.
b. The total organic carbon test (TOC) was not always
reproducible within the same sample. This is believed
due to the syringe injection technique which would not
pass particulate matter and to the small amount of
sample that could be injected.
c. The high heavy metal concentration apparently exceeded
the threshold inhibitory concentrations in the BOD
test causing great variations in values.
4. Approximately 40 to 50 percent of the COD in urban land runoff
is susceptible to biodegradation in twenty days.
5. The oxygen exertion or demand rate (k^) for urban land runoff
varies from 0.06 to 0.27 per day to the base e.
6. A vertical distribution of pollutant concentrations within urban
drainage channels was found to exist with concentrations increas-
ing with depth from the surface.
7. Through regression analysis, it was found that the significant
independent variables affecting stormwater quality were rate
of discharge (CFS) and time from storm start (TFSS) as indicated
by the initiation of runoff. The elapsed time from the last storm
was not found to be a significant parameter. Pollutant concen-
trations tended to increase with> an increase in rate of runoff and
decrease as the time from storm start increased, thus indicating
a first-flush effect. The prediction equations for the pollutants
investigated in mg/1 are presented on the following page.
8. The annual urban runoff pollutant yield during the 1972 calendar
year from each acre drained was found to be 938 pounds COD, 187
pounds TOC, 7700 pounds total solids, 1458 pounds total volatile
solids, 6691 pounds suspended solids, 797 pounds volatile sus-
pended solids, 6.1 pounds kjeldahl nitrogen, 4.7 pounds total
phosphorus, 64 pounds aluminum, 52 pounds calcium, 1.9 pounds
cobalt, 1.6 pounds chromium, 1.6 pounds copper, 102 pounds iron,
71 pounds magnesium, 4.9 pounds manganese, 1.2 pounds nickel,
2.9 pounds lead, and 2 pounds of zinc.
9. During wet periods (approximately 20 percent of the 1972 calendar
year) the yield of organics measured as COD in urban runoff was
approximately 4-1/2 times the organic yield of raw sewage while
the suspended solids yield in urban runoff was approximately 100
times that in the raw sewage.
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REGRESSION EQUATIONS PREDICTING POLLUTANT
CONCENTRATION (MG/L) IN URBAN LAND RUNOFF IN
A NATURAL CHANNEL CORRECTED TO FLOW AT MID-DEPTH*
Pollutant
COD
TOG
TS
TVS
TSS
VSS
Kjel. N.
Total P.
Al**
Ca
Co**
Cr
Cu**
Fe
Pb
Mg
Mn
Ni**
Zn
MG/L
113.
32.
420.
130.
222.
44.
0.85
0.80
10.
12.5
0.07
0.18
0.08
4.6
0.27
10.
0.45
0.12
0.22
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
CFS
0
0
0
0
0
0
0
0
0
-
-
0
0
0
-
0
0
0
.11
.0
.14
.09
.23
.18
.87
.03
.05
.4
.18
.04
.10
.24
.125
.02
.11
.03
.10
TFSS °
TFSS~'
TFSS"'
TFSS"'
TFSS"'
TFSS"'
TFSS"'
TFSS"'
TFSS"'
TFSS"'
TFSS"1"'
TFSS4"'
TFSS+'
TFSS"'
TFSS"'
TFSS"'
TFSS"'
TFSS+'
TFSS"'
.28
28
18
11
16
17
29
29
15
09
13
06
08
18
29
16
27
01
22
10.
*CFS = Cubic Feet Per Second
*TFSS = Time from Storm Start (hours)
** = Mid-depth Correction assumed as 0.9
Approximately 20 percent of the time downstream water quality
was judged to be primarily governed by non-point urban land
runoff.
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11. Fifteen minutes of ideal quiescent settling of urban land runoff
will remove an average of 60 percent of the COD, 77 percent of
the suspended solids, and 50 percent of the turbidity.
12. Alum, with or without coagulant aids, was judged the most effec-
tive coagulant in COD, suspended solids, and turbidity removal.
Average removal efficiencies, based on jar test results with alum,
indicated 84, 97, and 94 percent of the COD, suspended solids,
and turbidity, respectively, could be removed with an average
dose resulting in an initial concentration of 50 to 60 mg/1.
13. Significant improvements in downstream oxygen levels may be
obtained through the use of storage impoundments to exploit the
effects of plain sedimentation.
14. It is conceivable that the use of the 7-day, 10-year low flow
criterion for controlling water quality is misleading. During
this study, it appeared that critical water quality conditions
are not typified by the 10-year, 7-day low flow but by the period
immediately following low flow when rainfall removes accumulated
urban filth into the receiving watercourse, greatly increasing
the pollutant load, while not substantially increasing water
quantity.
15. Certain forms of solid waste such as beer cans, broken glass
bottles, garbage, bed springs, and shopping carts were found in
the Third Fork Basin. These solid wastes, believed to be typi-
cal of urban streams, not only contribute to lower water quality
but are aesthetic pollutants and a hazard to public safety as
well.
16. The EPA Storm Water Management Model predicts fairly accurately
the hydrograph resulting from the specific storms evaluated. It
does not, however, accurately predict pollutant concentrations
for the natural stream beds existing in Durham, North Carolina.
17. Results of a hypothetical evaluation of the impact of urban land
runoff on downstream water quality in Third Fork Creek indicate
that during storm flows, dissolved oxygen content of the receiv-
ing watercourse is independent of the degree of treatment of
municipal wastes beyond secondary treatment. Oxygen sag esti-
mates are unchanged even if the secondary plant is upgraded to
zero discharge. Therefore, if a desired water quality is to be
maintained during storm flow conditions, stormwater treatment is
necessary.
18. Before upgrading secondary municipal waste plants, concomitant
steps should be taken to moderate the adverse effects from urban
land runoff.
19. The relative economics of stormwater treatment are highly sensi-
tive to such local parameters as the nature of quality standards,
the nature of existing facilities, and the degree of stormwater
treatment required.
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SECTION II
RECOMMENDATIONS
More extensive study of urban runoff is obviously necessary. At the
same time efforts should be made to educate the public to the nature
and importance of this non-point waste source. It may be easier to let
the public rest, believing point source treatment is the complete
answer, but in the long run such a course is not in the best interest
of water pollution control. Optimum allocation of public funds for
water quality management cannot be realized until sufficient information
is available on all pollutant sources potentially capable of impairing
water quality.
Urban land runoff is a significant non-point source of pollution;
guidelines indicating specific stormwater control standards may soon
be issued for urban areas where downstream water quality is partially
controlled by urban land runoff. Such regulations typically specify
minimum dissolved oxygen concentrations. At present it is virtually
impossible to predict, with any assurance of accuracy, the variations
of constants associated with oxygen-sag equations during urban runoff
events. These constants (kj_, k£, and k3) have been evaluated for
extreme low-flow situations, but no indepth studies of constant varia-
tions associated with high flows exist. It is, therefore, recommended
that studies be initiated to define the magnitudes of k-^, the oxygen
exertion rate constant; k£, the reaeration rate constant; and kg, the
rate of removal of oxygen demand by sedimentation during high flows.
The relative effect of urban land runoff on water quality management
can be assessed only when the contributions of other non-point sources
are quantified. Consequently, additional information is required on
all non-point pollution sources including but not limited to forested
areas, farmlands, pasture land, and park land. Only by being able to
describe accurately the total input of point and non-point sources dur-
ing wet weather can decisions be made with any certainty.
Urban areas planning to upgrade secondary sewage treatment plants
because of possible contravention of stream standards should carefully
assess the potential contravention by urban land runoff.
The chemical oxygen demand (COD) test should be considered the most
reliable analytical method of assessing the organic content of urban
land runoff. The COD uptake technique should be utilized to assess
the fraction of COD susceptible to biodegradation and to determine
oxygen demand rates.
Watercourses designated as water quality limited should be evaluated
with respect to the relative impact of non-point pollution sources.
The scale effect of varying urban drainage basin size on annual pollu-
tional yield from urban land runoff needs additional evaluation.
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A full-scale evaluation of the efficiency, economics, and applicability
of a holding-sedimentation facility to reduce the impact of urban land
runoff on water quality should be made. Included within this study
should be a careful assessment of the visual effect of the device and
the public's acceptance of the facility.
If partial or total treatment of urban land runoff is desirable, com-
bined sewers offer economic advantages over separate systems. It is,
therefore, recommended that municipalities re-evaluate the advantages
of separate versus combined sewers.
The EPA Storm Water Management Model does not satisfactorily predict
solids and organic concentrations in the Durham watershed. It is,
therefore, recommended that the predictive algorithm be re-examined.
It is also recommended that COD be substituted for BOD as the predictive
organic parameter.
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SECTION III
INTRODUCTION
The most obvious, easily recognizable sources of water pollution are
untreated or undertreated domestic and industrial wastes. In urban
areas, untreated point sources pose the greatest single threat to water
quality. Consequently, point sources have long been studied, and much
has~Been learned which can and is being used to diminish or in some
cases eliminate the influence of point waste sources on water quality.
This fight against point source pollution has been greatly aided by
public willingness to allocate funds to provide more and better treat-
ment plants in attempts to protect water quality. Indeed, improved
plant performance has become virtually synonymous with increased water
quality.
Unfortunately, better treatment plants as they are most often designed
do not always produce proportionate improvement in overall water
quality. A sewage treatment plant, however sophisticated, can only
treat that portion of the total urban pollution load it receives.
While urban point waste sources are treated and are becoming less
threatening, other non-point sources of water impairment become rela-
tively more significant. As non-point sources typically do not enter
treatment facilities and since they have not been sufficiently evalu-
ated, they constitute a double hazard.
First, there is the risk of public disillusionment. A community may
make expensive sewage treatment plant improvements and still fail to
achieve adequate water quality. Resulting public outrage or worse,
apathy, could potentially result in reduced appropriations for much
needed water quality management projects.
The second danger is that point source treatment may satisfy a com-
placent public. A discussion of a recent Council on Environmental
Quality study indicated that in 80 percent of the urban areas studied,
downstream quality was not controlled by point sources (2).
Non-point urban runoff is generated by precipitation which washes and
cleanses an urban environment, and then transports the dirt, filth,
etc. to the nearest natural or man-made watercourse. Considering that
precipitation cleanses homes, cars, streets, industries, shopping cen-
ters, etc. it is not surprising that urban surface waters contain sub-
stantial amounts of organics, solids, nutrients, heavy metals, and
micro-organisms. Urban surface waters are typically collected in storm
sewers, combined sewers, or may appear as diffuse surface water and
flow into the nearest urban stream or artificial channel. In any
event, the impact of this waste source on water quality management
objectives is significant.
More extensive study of urban runoff is obviously necessary. At the
same time efforts should be made to educate the public to the nature and
importance of this non-point waste source. It may be easier to let the
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public rest, believing point source treatment is the complete answer,
but in the long run, such a course is not in the best interest of water
pollution control. Optimum allocation of public funds for water quality
management cannot be realized until sufficient information is available
on all pollutant sources potentially capable of impairing water quality.
Domestic and industrial raw waste loads can be characterized in pollu-
tant generation per capita per day and gallons per capita per day,
whereas waste loads cannot be accurately quantified presently for urban
land runoff. The effect of domestic and industrial sewage on water
quality can be projected with some degree of reliability because its
dominant characteristics are known, whereas such projections cannot be
made for urban land runoff because it has not been adequately described.
Facility designs of municipal waste treatment plants are based on known
pollutant quantities from continuous sources, whereas stormwater facili-
ties have to be based on separate or intermittent surges. Cost informa-
tion is available for providing a desired degree of amelioration of
point sources, whereas similar information does not exist for urban land
runoff.
Stream standards historically have been used to provide a baseline
against which the relative impact of a waste on a receiving watercourse
is measured. The oxygen-sag model is used to predict minimum dissolved
oxygen concentrations for given hydrologic conditions; typically, the
10-year, 7-day low flow. During this extreme low-flow situation, one
assumes no contribution by non-point sources as extreme low flows are
indicative of no rainfall which means no runoff. However, it is con-
ceivable that critical conditions are not typified by the 10-year, 7-day
low flow but by the period immediately following the 10-year, 7-day low
flow when rainfall removes accumulated urban filth into the receiving
watercourse, greatly increasing the pollutant load while not substan-
tially increasing water quantity.
Several questions must be raised. At what time should municipalities
become concerned with urban runoff in relation to overall water quality?
When is it more economical to provide some degree of urban runoff
amelioration to achieve specified decreases in total urban pollutional
loads? Is sufficient information available for regulatory agencies to
adopt urban runoff treatment requirements? If a municipality desires to
reduce the urban runoff pollutional load, what is the least cost alter-
native to achieve a given reduction? Is sufficient information avail-
able to make these decisions?
Project Scope and Objectives
This project was initiated to provide information inputs to the above
questions. The specific objectives and scope of work were:
1. To characterize urban stormwater runoff with respect to
quantity and quality and land use,
2. To investigate and evaluate the applicability and effec-
tiveness of physiochemical treatment of urban runoff,
-------
3. To develop criteria for ascertaining the point at which an
increased degree of municipal waste treatment exceeded the
collection and treatment costs of urban runoff required to
achieve the same overall water quality management objectives,
and
4. To evaluate the applicability of the Environmental Protec-
tion Agency's Storm Water Management Model (SWMM) in predict-
ing the quality and quantity of urban runoff.
The urban drainage basin utilized in the study was the Third Fork Basin
located in Durham, North Carolina, the site of an earlier study by
Bryan (1) .
-------
SECTION IV
BASIN DESCRIPTION AND LAND USE
The Third Fork Creek drainage basin selected for study is located in the
south central portion of Durham, North Carolina, and is part of the New
Hope, Haw, and Cape Fear system. The City of Durham, North Carolina, is
located on a divide with the northern portion of the city draining into
the Neuse River system and the southern edge being a part of the greater
Cape Fear system. The upper Third Fork Creek basin has a 1.67 square-
mile (1093 acres) drainage basin completely within Durham city limits
with its northern boundary being located in the downtown business sec-
tion. The study area is served by a separate sanitary system. Figure 1
shows the location of Durham, North Carolina, within the State of North
Carolina and the location of the Third Fork Creek drainage basin within
Durham.
North Carolina
Figure 1.
Third Fork Creek study area location within
Durham city limits and North Carolina
10
-------
Third Fork Creek drainage basin is primarily composed of two shallow
valleys with relatively narrow flood plains located along the lower
portion of each. Excess surface waters in the basin flow into the head-
waters of Third Fork Creek through natural and man-made channels. The
stormwater runoff system is composed of overland flow, street gutters,
small pipes, and culverts under roads. No storm sewer system, as such,
exists; therefore, excess surface waters generally follow natural drain-
age patterns except for a small part of the northern edge of the drain-
age basin located in the downtown business district, denoted as Sub-
basin N-2 in Figure 2.
Basin
boundary
Figure 2. Drainage pattern of Third Fork Creek within Durham, N. C
11
-------
The basin was selected for study as it is representative of a typical
urbanized area occurring in the Piedmont region of the Southeastern
United States. The basin encompasses the varied land uses as listed
below:
• High and low density housing units of varying quality
• Undeveloped land
• Shopping centers
• Portion of the central business district
• Institutional buildings—churches, schools—among
scattered, small businesses
• An urban redevelopment section
• A tobacco manufacturing plant
* A completed section of expressway
• A cemetery
• Slums
• Railroad yard
• A flood plain utilized mainly as a city park
For the purpose of the study, the basin was divided into six sub-basins
and described with reference to the main gaging site. These sub-basins,
shown in Figure 2, were named for their direction from the main sampling
station [North (N), East (E), and West (W)] with a number (1 or 2)
denoting whether they were adjacent to the main sampling station at the
USGS gaging station or in the upper part of the basin. Table 1 presents
a summary of land use characterization, population, etc. as taken from
the 1970 block census data and topo maps.
A great diversity in land use, apparent personal income, and physical
basin features occurs within the urban Third Fork Creek basin. Sub-
basins W-l, W-2, E-l, and N-l are primarily residential areas. The
more affluent people reside in W-l where homes are in the $40,000 to
$150,000 range, whereas the least affluent live in E-l, E-2, and N-2
sub-basins where slums exist. Portions of N-2 and E-2 are undergoing
urban renewal. Sub-basin N-2 is primarily composed of a portion of the
downtown business district including light to heavy industry and a
cross-town expressway. Sub-basins E-l, E-2, and W-l essentially con-
tain no industry, business, or commercial property. The majority of
the streets in E-l and E-2 are unpaved. A small shopping center, a
large park surrounding the flood plain, and a few middle-income homes
typify N-l. Sub-basin W-2 has business and commercial property along
its upper divide with the remaining portions utilized primarily for
moderate income housing and a large cemetery. Population density within
the basin varies from 1.5 per acre in N-2 to 13.5 in E-l. Figures 3
through 17 portray typical land uses within the urban Third Fork Creek
drainage basin.
Pictures portraying the upper prongs of Third Fork Creek within the
Durham basin are presented in Figures 18 through 27.
12
-------
Table 1. THIRD FORK CREEK LAND USE CHARACTERIZATION BY SUB-BASINS
Sub-
basin
E-l
E-2
N-l
N-2
W-l
W-2
Total
Area
Acres
56
263
183
191
169
207
1069
I of
Total
5.2
24.6
17.1
17.9
15.8
19.4
100Z
Population
Density
Per Acre
13.5
6.9
3.8
1.5
3.5
10.8
6.0
Physical Features
Stream
Length
Feet
1312
3221
3350
3484
3282
2610
_
Stream
Slope
X
3
1.4
1.0
2.1
0.9
1.8
_
Mean
Land
Slope
%
9.2
5.2
7.4
8.1
8.4
9.1
_
% of Residential
Dwellings of
Lou
Quality
100
100
6
62
0
62
24
Med.
Quality
0
0
52
31
30
38
27
High
Quality
0
0
42
7
70
0
49
Percent Land
Resi-
dent.
100
50
63
18
85
73
59
Conun.
&
Indus .
0
36
8
44
0
4
19
Pub.
&
Inst.
0
9
19
13
15
9
12
Unused
0
5
10
25
0
14
10
Sub-basin Surface Characteristics
Z of Sub-basin
Paved
5
27
16
33
16
11
20
Roof-
tops
7
13
5
12
5
9
9
Unpaved
Streets
12
3
1
1
3
6
3
Vegetation
76
57
78
54
77
74
68
-------
Figure 3. Typical land use in Sub-basin E-l.
Figure 4. Typical land use in Sub-basin E-l,
14
-------
Figure 5. Typical land use in Sub-basin E-2.
Figure 6. Low-income housing in Sub-basin E-2,
15
-------
Figure 7. Typical land use in Sub-basin E-2.
Figure 8. Typical land use in Sub-basin N-l.
16
-------
Figure 9. Small shopping center in Sub-basin N-l.
Figure 10. City Park surrounding Third Fork Creek in Sub-basin N-l.
17
-------
Figure 11. Typical land use in Sub-basin N-2.
Figure 12. Typical land use in Sub-basin N-2,
18
-------
Figure 13. Typical land use showing cross-town
expressway in Sub-basin N-2.
-
Figure 14. Typical land use in Sub-basin N-2.
19
-------
Figure 15. Typical land use in Sub-basin W-l.
'
Figure 16. Public school in Sub-basin W-2.
20
-------
Figure 17. Typical land use in Sub-basin W-2.
Figure 18. Third Fork Creek above gaging station.
21
-------
- - • ' - - -i- -J5,
• & ----- - - ' -.
- •• ~ _ , »-> • • • ^ '^-
: .-;:^ -.r v -t,.^
Figure 19. Third Fork Creek channel behind small shopping center.
Figure 20. Prong of Third Fork Creek in Sub-basin N-l.
22
-------
Figure 21. Culvert in Sub-basin W-l.
•*$*
Figure 22. Trash in creek in Sub-basin W-2.
23
-------
Figure 23. Trash in creek in Sub-basin N-l.
Figure 24. Trash in stream in Sub-basin N-l.
24
-------
Figure 25. Stream in Sub-basin W-2
• ig^-jr ***&*£.••'•_*.*£
' ^MC^^f.','~^jd-** IN _' *fi t '•"
*s£m w«X« tJ^-*££jfe*-£
.y 7
LpV.B; . j#-T»
'*:'i"^^' -' *'
iii;'*«*»•-• ,»' - ! ». « '. • I
Figure 26. Trash in stream in Sub-basin W-2.
25
-------
Figure 27. Trash in stream bed in Sub-basin W-2.
26
-------
SECTION V
SAMPLING
Hydrologic Data
The United States Geological Survey operates a continuous stage recorder
(Station No. 02097243) and two digital punch tape recorders within the
1.67 square-mile drainage basin. The stage recorder and one precipita-
tion station are located at the main gaging site at the bottom of the
selected drainage basin. The gage house, shown in Figure 28, is
located on the right bank of the Third Fork Creek, 62 feet downstream
from a bridge on Forest Hills Boulevard and 7 miles upstream from the
mouth of Third Fork Creek. Stream-flow control is provided by a
V-notch weir.
Automatic Sampler
The procurement of samples during periods of runoff presented a problem
as no readily available commercial samplers were judged satisfactory
for the conditions at the sampling location. The special requirements
were:
1. Samples had to be obtained directly out of the stream
located adjacent to the USGS gage weir.
2. The sampler had to be small enough to not interfere with
the flow of water over the weir and not act as an obstruc-
tion to catch debris washed downstream during storms.
3. The sampler had to be able to pass large quantities of
sand, leaves, and other solids without clogging and yet be
immune to damage from larger floating objects such as beer
cans, railroad cross ties, tire carcasses, and shopping
carts.
4. The sampling mechanism had to have the capability of start-
ing by itself during each runoff event when the stage
reached a predetermined level indicating initiation of run-
off. [This was necessitated by the basin being approxi-
mately thirty miles from the University and mainly because
it is impossible to estimate initiation of runoff from
weather forecasts. It appeared that most events started
after midnight and before 8:00 a.m.]
5. The sampling system had to be able to take discrete samples
at predetermined intervals with a known time of the first
sample and last sample. This was needed to correlate water
quality with the exact quantity and time of runoff.
6. The entire system had to be free from potential vandalism.
7- An appearance before the Durham City Council was required
to allay fears of nearby citizens that the sampling station
would be an unsightly addition to the park.
27
-------
— o
15 10
Stationing, in Feet
Figure 28. Schematic diagram showing location and relative elevations
of USGS gage house and control weir.
28
-------
8. The water velocity through the system had to be sufficient to
keep all material in suspension to obtain representative sam-
ples and minimize system clogging.
The system designed and installed to meet the desired objectives con-
sisted of the following main items:
1. A 1/2 H.P. Enpo-Cornell Model 150 submersible pump with
mechanical seal and cast iron impeller capable of pumping
50 GPM against a 12-foot head.
2. An electronic control box capable of sensing increases in
stage with a 1 to 60-minute interval timer.
3. A plexiglass sampling flume 10 inches high, 36 inches long,
and 1 inch wide.
4. A 24-bottle Serco vacuum sampler modified with a Minarik
motor for sample procurement.
The submersible pump, housed in a steel box with approximately 300 one-
inch-diameter holes, was located in the middle of the stream approxi-
mately five feet below the USGS weir. The pump box was securely
fastened to two 7-foot steel pipes driven into the stream bed holding
the pump securely in place. All samples taken, therefore, came from
the lower or bottom portion of the runoff hydrograph. Substantial
wear occurred to the impeller and volute casing necessitating pump
repair and/or replacements. The pump would occasionally become clogged
during a runoff event which stopped the sampling procedure.
The electronic control box located in the USGS building provided sev-
eral control functions. These were:
1. A probe dropped into the wet well at a predetermined eleva-
tion corresponding to a 0.7-foot stage so selected as to
indicate runoff initiation. When the water in the wet well
touched the probe, the sampling system would automatically
turn on.
2. One of two clocks running connected to the control panel
would turn off indicating the time of sampling initiation.
3. The control panel would turn on the submersible pump. If
for some reason the pump did not have at least 7 inches of
water flowing through the flume in two minutes, a sensor
would turn the system off to protect it from damage.
4. A l-to-60-minute interval time on the control box was set to
select the time period between discrete samples. With 24
sample bottles, samples could conceivable be taken each hour
for 24 hours. However, during the period of this study, the
selected interval was 30 minutes or less.
5. A plexiglass sampling flume was designed to guarantee no
sediment deposition at a flow rate of 50 GPM. The water
entered at one end of the flume and was discharged back to the
29
-------
creek through a pipe at the other end. The sampling head was
attached close to the discharge end of the flume.
6. The Serco vacuum sampler had 24, 0.5-liter sample bottles.
Prior to sampling, a vacuum was placed in the bottles by
means of a vacuum pump with a special head designed to fit
over the sampling head when removed from the flume. The
vacuum pump was allowed to run 5 minutes to ensure a maximum
vacuum on each bottle. The vacuum pump was then removed,
and the sampling head securely fastened to the sampling flume.
7. A slow-speed Minarik motor was vertically attached to the out-
side of the sampler body and connected to a vertical shaft by
a chain and two sprockets. The larger sprocket, attached to
the center shaft, had 24 screws placed through the rim. Each
screw indicated 1/24 of a revolution or how much rotation was
needed by the shaft to release the vacuum on each sample bot-
tle when indicated by the interval time. A relay switch,
attached to the body of the sampler and activated by coming
into contact with the screws in the sprocket, turned the motor
off when sufficient movement had occurred to release the vacuum
on the selected bottle. When the vacuum was released, the bot-
tle would draw in approximately 350 milliliters of sample from
the sampling flume. When the 24th sample was taken, the sam-
pling system would automatically turn off, activating a second
clock indicating the time of the last sample.
Although the sampling system was not 100 percent reliable, it was
judged to be fairly reliable considering the type of material being
sampled and the adverse conditions under which sampling occurred.
A schematic of the automatic sampling system is shown in Figure 29.
Illustrations of the gage house and the sampling are given in Figures
30 through 36.
30
-------
Flow
Weir
Control
Box
Probes
Wet
Well
Pump
THIRD FORK CREEK
Sampling
Flume
Relay
Switch
Automatic
Sampler
Figure 29. Schematic of automatic sampling system.
-------
Figure 30. USGS gage house adjacent to Third Fork Creek.
-JftaL
Figure 31. USGS control weir and staff gage at gaging station.
32
-------
Figure 32. Box housing submersible pump at sampling station.
Figure 33. Automatic sampler control box,
33
-------
Figure 34. Stage recorder and digital precipitation
recorder inside USGS gage house.
Figure 35. Plexiglass sampling flume.
34
-------
Figure 36. Modified vacuum sampler,
35
-------
SECTION VI
CHARACTERIZATION OF URBAN LAND RUNOFF
Hydrologic Information
Thirty-six separate runoff events were sampled during the project period
producing a total of 521 separate samples. A summary of information
describing the hydrologic and time parameters associated with each storm
sampled is presented in Table 2. Each storm sampled was assigned a
sequential number used here and elsewhere to denote the specific storm
sampled. The hydrologic information given for each storm includes the
inches of precipitation, storm duration, average intensity, inches of
runoff, runoff coefficient, and antecedent dry period. The hydrologic
characteristics of the storms vary from a short intense summer thunder-
storm (#21) to a 30-hour drizzle (#1). Runoff coefficients vary from
0.006 to 0.90, and the peak discharge associated with each storm varies
from 2.25 to 1740 cfs. The number of dry days preceding each storm
varies from 0.5 to 34.
Storm Nos. 1 and 2 were manually sampled at the surface prior to ade-
quate installation and operation of the automated sampling system which
procured its samples adjacent to the stream bed. The hydrologic infor-
mation for Storm No. 30 is not available due to a malfunction of the
stage and precipitation recording equipment.
The number of samples taken during a storm ranged from 3 to 26. This
great diversity in the number of storm samples was due to clogging of
the submersible pump by material which caused the sampling system to
cut off automatically. This problem seemed excessive during the fall
when dead leaves washed from the basin.
The great variance in storm characteristics is believed to reflect the
diversity in the occurrence of natural events.
Individual Storm Characterization
The average COD, TOC, and BOD with standard deviations for each storm
sampled is presented in Table 3. These three organic indicators were
run on each sample where indicated. COD is believed to be the most con-
sistent measurement of relative storm strength for three reasons:
1. COD values were reproducible in the lab and were not affected
by particle size and inhibitory compounds.
2. TOC was not always reproducible within the same sample. This
is believed due to the syringe injection technique which
would not pass particulate matter and to the small amount of
sample that could be injected.
3. The high heavy metal concentrations apparently exceeded thresh-
old inhibitory concentrations in the BOD test causing great
variations in BOD values.
36
-------
Table 2. HYDROLOGIC DESCRIPTION OF URBAN RUNOFF EVENTS SAMPLED
Date
10/23/71
11/24/71
12/16/71
12/20/71
1/4/72
1/10/72
2/1-2/72
2/12-13/72
2/18/72
2/23/72
2/26/72
3/8/72
3/16/72
3/31/72
4/12/72
5/3/72
5/14/72
5/22/72
5/30-31/72
6/20/72
6/28/72
7/11/72
7/12/72
7/17/72
7/31/72
8/28/72
9/17/72
9/21/72
10/5/72
10/19/72
11/14/72
11/19/72
11/30/72
1/19/73
2/26/73
3/21/73
Storm
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Rainfall
Inches
1.55
-
0.05
0.43
0.2
0.55
1.19
0.96
0.44
0.13
0.19
0.04
0.6
0.46
0.33
1.14
0.71
0.92
0.25
0.24
1.78
0.1
0.33
0.26
0.38
0.06
1.51
0.5
2.36
0.74
0.79
0.5
0.11
0.4
0.25
hiratlon
Hours
32.5
NO FREI
0.5
19.5
2.5
12.0
10
10
8
0.5
0.5
0.083
10.33
11.33
2.17
7.25
8.0
15.5
10.0
6.5
2.13
0.5
3.83
1.0
2.5
2.1
3.3
9.0
26.0
3.63
4.0
14
1.25
1.6
5.0
ntenslty
In/hr
0.047
PITATION
0.1
0.022
0.08
0.046
0.119
0.096
0.049
0.26
0.38
0.48
0.058
0.04
0.15
0.15
0.089
0.059
0.025
0.037
0.83
0.2
0.086
0.26
0.15
0.028
0.45
0.055
0.34
0.2
0.19
0.04
0.09
0.25
0.05
unof f
nches
0.88
RECORD!
0.003
0.15
0.04
0.19
0.84
0.54
0.2
0.04
0.03
0.01
0.36
0.15
0.12
0.47
0.29
0.513
0.03
0.07
1.55
0.005
0.083
0.15
0.34
0.004
0.7
0.083
2.07
ECOHDE
0.25
0.48
0.09
0.03
0.09
0.05
Runoff
oefficient
0.54
AVAILABLE
0.0061
0.34
0.19
0.34
0.7
0.56
0.45
0.29
0.18
0.25
0.59
0.33
0.35
0.41
0.41
0.56
0.12
0.29
0.87
0.054
0.25
0.57
0.9
0.066
0.46
0.16
0.88
S INOPERABLJ
0.34
0.61
0.18
0.30
0.24
0.23
Peak
Is charge
CFS
33.2
->
2.5
31.3
22.6
63.0
138.4
126.6
32.0
22.0
19.0
4.3
51.8
40.6
73.0
135.7
109.0
349.0
29.9
75.4
1740
2.25
36.2
125.0
152.0
2.58
700.0
41.4
872.0
-*•
120.8
106.0
57
27.8
83
38
ays Since
,ast Storm
3.25
34.0
4.0
0.5
4.75
1.0
11.5
9.0
5.5
5.5
2.83
4.88
7.25
9.5
4.25
21.0
5.5
5.0
5.62
20.5
7.17
6.54
7.33
5.25
0.75
6.54
11.3
3.5
5.0
6.0
2.45
4.6
4.2
12.1
4.1
o. Samples
Taken
15
13
10
16
9
19
27
20
27
a
23
15
23
23
17
21
24
9
8
16
5
4
15
7
20
3
10
10
7
11
9
20
12
26
3
16
37
-------
Table 3. AVERAGE AND STANDARD DEVIATION OF
ORGANICS IN URBAN RUNOFF EVENTS
AT THE MAIN GAGING STATION
Storm
Number
1
2
3
it
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
COD
mg/1
Avg
25
259
111
171
146
141
195
143
149
125
171
82
176
123
89
257
150
41
144
220
271
402
96
348
187
184
253
140
142
157
132
110
93
374
289
92
a
14
62
21
45
89
60
103
104
116
96
146
39
144
73
49
190
175
7
106
135
130
430
52
198
79
80
232
60
59
69
83
77
28
103
101
31
TOC
mg/1
Avg '
30
36
35
25
36
33
24
36
36
36
44
46
36
17
15
16
41
39
73
165
26
94
48
50
51
21
38
44
49
34
38
105
99
31
o
7
7
34
11
41
16
17
27
25
10
30
20
12
12
8
5
25
18
30
148
9
41
14
18
41
11
16
13
15
10
14
35
19
14
BOD
mg/1
Avz
18
18
17
6
2
15
20
18
42
5
55
105
73
100
80
16
220
41
138
182
80
49
50
100
a
14
13
12
6
.4
11
12
9
11
3
14
23
10
5
19
2
10
24
15
60
74
20
12
20
38
-------
Individual concentrations for each sample are presented in the Appendix.
The variation in COD, TOG, and BOD concentrations and flow rate within
two typical storms as a function of time are presented in Figures 37
and 39. 6
The average and standard deviation of solids for each storm is presented
in Table 4. Typical variations in solids concentration with rate of
flow and time from initiation of runoff are presented in Figures 37 and
39. The complete solids analysis for each storm is presented in the
Appendix.
The average and standard deviation of total phosphorus (as P), kjeldahl
nitrogen, and fecal coliforms are presented for each of the storms in
Table 5. The comparatively high nitrogen concentration of Storm Nos. 3
and 4 are believed erroneous. The individual nitrogen, phosphorus, and
fecal coliform analysis for each sample is provided in the Appendix.
Typical variations of kjeldahl nitrogen, total phosphorus and fecal
coliform concentration with rate of flow and time since the beginning
of the storm are presented in Figures 38 and 40.
The average and standard deviation of metals concentration for the
storms sampled are presented in Table 6. The actual metal concentra-
tions for each sample are presented in the Appendix.
The average, standard deviations and range of all pollutants for samples
collected are presented in Table 7. It is interesting to note the large
variance of pollutant concentrations of urban runoff. These averages
represent only those samples procured by the automatic sampler.
Base Flow Characterization
Base flow analyses were made 32 times during the project at the USGS
gaging station on Third Fork Creek and less often at individual sub-
basin discharge locations. The average base flow water quality for the
total basin and the sub-basins are presented in Table 8. The individual
observations for each sub-basin are included in the Appendix. The
quality of the N-2 sub-basin is worse than for the other basins and is
believed due to illegal connections.
Effect of Land Use on Water Quality
In order to assess the impact of varying types of land use within the
basin on urban runoff quality, 5 storms were manually sampled at the
sub-basin discharge locations. It was believed that a varying quality
of urban runoff from the sub-basins should reflect impacts of varying
land use.
A control section, usually a pipe or box culvert, was utilized with
Manning's equation to arrive at stage discharge relationships for each
sub-basin sampled. During the 5 selected storms the stage was manually
read when the sample was taken. By knowing the discharge rate for each
sample and the corresponding time, a discharge hydrograph for each storm
was obtained along with pollutant concentrations.
39
-------
1200 —
900 —
- Fecal Cclifonn
Q Total Suspended Solids
- Total Volatile Solids
O - Total Solids
Volatile Suspended Solid
Time
605
400
300
;200
100
80
70
60
50
40
30
20
10
i i i rii n r r
0500 0600 0700 0800 0900 1000 1100 1200 1300
Time (hrs)
Figure 37. Pollutant variations with Q and time for
Storm No. 20, Date 6/20/72.
40
-------
15
12
18
20
D - Iron
A - Manganese
O - Total P
I I
I I
I T
1.5
1.2
0.9
0.6
0.3
K-Nltrogen
Lead
80
70
60
50
u
cr
30
20
10
^ I I 1 I I I I I
0500 0600 0700 0800 0900 1000 1100 1200 1300
Time (hrs)
Figure 38. Pollutant variations with Q and time for
Storm No. 20, Date 6/20/72.
41
-------
2200
2000
1800
1600
1400
1200
1000
800
600
400
200
O Total Solids
Q - Total Suspended Solids
Q - Total Volatile Solids
A - Volatile Suspended Solids
500
400 '
o 300
200
100
I I I II I
1700 1800 1900 2000 2100 2200
Time (hrs)
\ I I
2300 2400 0100
50
40
30 £
o
20
10
Figure 39. Pollutant variations with Q and time for
Storm No. 13, Date 3/16/72.
42
-------
1.6
O ~ Manganese
D - K-Nitrogen
O - Zinc
- 10
I I \ I l^ I I I
1700 1800 1900 2000 2100 2200 2300 2400 0.00
Time (hrs)
Figure 40. Pollutant variations with Q and time for
Storm No. 13, Date 3/16/72.
43
-------
Table 4. AVERAGE AND STANDARD DEVIATIONS OF SOLIDS
IN URBAN RUNOFF EVENTS AT THE
MAIN GAGING STATION
Storm
Number
1
2
3
4
5
6
7
8
9
10
U
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Total Solids
mg/1
Avg
226
538
571
520
676
1675
1423
982
1169
391
913
1124
960
1932
1583
1215
991
871
2460
3940
682
3570
3080
5423
3300
1147
1487
1050
1144
1497
1822
1234
719
0
27
143
186
264
294
492
874
384
453
63
574
435
412
1273
506
1197
426
324
467
2820
319
908
1117
2597
3076
343
664
588
913
542
941
258
152
Volatile Solids
mK/1
Avg
78
215
147
148
182
133
107
110
145
288
500
168
485
224
323
283
147
186
242
138
260
285
284
177
a
18
84
39
29
65
44
17
51
40
88
452
29
102
123
127
182
38
60
56
43
41
135
45
30
Total Suspended
mR/1
AVR
89
274
163
346
474
1459
1233
1754
572
990
146
687
108}
843
2596
1525
849
899
895
2732
2332
554
2889
3913
2522
1024
1326
1340
83
777
1246
1463
1029
643
a
38
164
86
272
249
535
949
1194
421
733
58
472
492
429
2107
655
1117
576
789
725
1090
290
1266
2204
2434
376
624
1100
62
788
550
923
288
202
Volatile Suspended
mg/1
Avg
75
15
119
92
121
152
132
76
82
129
240
380
40
318
136
152
221
71
105
147
14
120
145
188
136
104
0
91
8
68
36
40
102
208
15
74
101
67
395
27
129
93
101
149
25
49
24
7
53
40
97
10
17
44
-------
Table 5. AVERAGE AND STANDARD DEVIATION OF
TOTAL PHOSPHORUS, KJELDAHL NITRO-
GEN, AND FECAL COLIFORMS IN URBAN
RUNOFF EVENTS AT THE MAIN GAGING STATION
Storm
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
16
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Total P
mu/1
Avg
0.28
0.6
1.03
0.47
1.05
0.75
1.07
0.58
0.5
0.57
1.05
0.81
1.98
1.03
0.56
0.56
0.62
1.09
1.17
1.13
0.44
1.42
0.73
0.85
0.36
0.71
.71
0.92
0.6
1.54
0.59
-------
Table 6. AVERAGE AND STANDARD DEVIATION OF METALS CONCENTRATION IN
URBAN RUNOFF EVENTS AT THE MAIN GAGING STATION
Storm
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
16
19
20
21
22
23
24
25
26
27
28
29
30
31
32
3°
34
35
36
Calcium
mg/1
Av£
7.0
2.5
2.7
5.5
4.1
14.3
6.2
24.7
5.3
4.2
5.2
2.3
2.1
0
7.8
0.5
1.6
7.9
1.3
14.2
3.5
4.9
1.3
1.4
3.7
0.8
1.3
Cobalt
mj>/l
Avg
0.36
0.13
0.08
0.14
0.1
0.09
0
0.09
0.03
0.04
0.05
0.0
0.00
Copper
n>R/l
Avg
0.36
.14
0.10
0,13
0.15
0.10
0.10
0.14
0.12
0.12
0.12
0.13
a
0.10
.03
0.03
0.03
0.07
0.00
0.00
0.02
0.01
0.02
0.02
0
Chromium
me /I
Avg
.31
0.33
0.31
0.27
0.29
0.27
0.16
0.11
0.10
0.10
0.15
0.16
0.11
a
.07
0.08
0.06
0.03
0.09
0.07
0.09
0.03
0.00
0.04
0.04
0.03
0
Iron
HlR/1
Avg
4.4
3.5
3.6
10.6
9.1
11.2
11.4
9.9
9.1
7.8
16.3
3.7
13.6
9.3
7.7
12.9
12.1
32.8
19.0
18.8
19.6
a
1.3
.8
1.7
2.9
4.2
4.1
4.9
6.3
it. 7
3.9
14.5
1.0
9.7
3.5
4.4
8.3
8.2
14.6
5.6
9.3
9.4
Lead
OK/1
Avg
,49
0,43
0.53
0.57
0.40
0.42
0.43
0.35
0.47
0.57
0.26
0.38
0.29
0.23
0.45
0.23
0.10
0.47
0.49
0.79
0.26
0.20
0.28
1.19
0.69
0.24
0
.11
0.07
0.09
0.24
0.14
0.22
0.16
0.26
0.30
0.80
0.12
0.29
0.14
0.15
0.46
0.17
0.00
0.54
0.38
0.75
0.09
0.26
0.12
0.32
0.14
0.08
Nickel
mg 1
Avg
.16
0.16
0.18
0.1
0.09
0
.04
0.03
0.04
0.0
0.00
Magnesium
nR/1
Avg
11.7
9.3
9.1
10.6
8.5
11.2
15.2
9.4
3.9
8.6
7.7
13.4
12.4
4.7
11.9
7.2
12.6
15.5
a
4.7
2.1
3.5
5.4
2.2
3.2
4.0
1.6
.3
2.4
1.1
1.4
1.2
0.8
1.6
2.2
4.4
2.5
Manganese
rag/
Av«
.59
0.71
0.60
0.62
0.63
0.69
0.56
0.52
0.64
0.89
0.44
0.51
0.43
0.33
1.07
0.95
2.01
0.71
0.40
1.67
1.32
0.60
0.44
o
.10
0.26
0.11
0.24
0.23
0.37
0.26
0.16
0.14
0.44
0.06
0.29
0.22
0.18
0.76
0.63
0.38
0.17
0.25
0.24
0.91
0.16
0.08
Zinc
n.E/1
Avg
0.27
.19
0.17
0.32
0.31
0.24
0.34
0.27
0.68
0.58
0.96
0.21
0.36
0.25
0.21
0.50
0.25
0.10
0.83
0.42
0,22
0.53
0.34
0.33
0.28
0.28
a
0.27
.04
0.08
0.08
0.15
0.10
0.19
0.15
0.91
0.29
0.88
0.06
0.29
0.10
0.11
0.37
0.16
0,01
0.37
0'.06
0.10
0.19
0.11
0.23
0.14
0.05
-------
Table 7. AVERAGE, RANGE, AND STANDARD DEVIATION OF POLLUTANT
CONCENTRATIONS FOR ALL STORM SAMPLES
Pollutant
COD
TOC
Total Solids
Volatile Solids
Total Suspended Solids
Volatile Suspended Solids
Kjeldahl Nitrogen as "N"
Total Phosphorus as "P"
Fecal Coliform (#/ml)
Aluminum
Calcium
Cobalt
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Zinc
Alkalinity
Mean
mg/1
170
42
1440
205
1223
122
.96
.82
230
16
4.8
.16
.23
.15
12
.46
10
.67
.15
.36
56
Standard
deviation
135
35
1270
124
1213
100
1.8
1.0
240
8.15
5.6
.11
.10
.09
9.1
.38
4.0
.42
.05
.37
30
Range (mg/1)
Low
20
5.5
194
33
27
5
.1
.2
1
6
1.1
.04
.06
.04
1.3
0.1
3.6
.12
.09
.09
24
High
1042
384
8620
1170
7340
970
11.6
16
2000
35.7
31
.47
.47
.50
58.7
2.86
24
3.2
.29
4.6
124
Table 8. AVERAGE BASE FLOW POLLUTANT CONCENTRATION FOR
SUB-BASINS AND MAIN GAGING STATION
Sub-basin
Dissolved oxygen (mg/1)
Organics (mg/1) - COD
TOC
BOD5
Solids (mg/1) - TS
TVS
SS
vss
Nutrients (mg/1)- K-N
Total-P
Fecal Coliform (#/ml)
Metals (mg/1) - Ca
Co
Cr
Cu
Fe
Mg
Mn
Ni
Pb
Zn
E-l
8.8
21
17
10
358
98
82
14
1.0
.1
8
45
.10
.25
.10
2.3
13.4
1.3
.19
.27
.13
E-2
9.7
24
13
10
392
107
20
16
1.0
•2
30
45
.15
.21
.16
1.4
17.7
.50
.15
.24
.15
N-2
7.5
81
29
25
428
101
25
18
1.4
1.8
50
21
.10
.30
.14
1.4
11.2
.47
.17
.21
.51
W-l
8.8
22
15
8
250
81
20
11
1.5
.3
120
29
.13
.23
.11
1.2
11.4
.42
.19
.18
W-2
9.9
28
17
18
289
85
24
16
2.6
.7
70
30
.17
.26
.14
2.8
12.4
.40
.20
.19
.11
Total
basin
8.4
29
14
15
400
90
50
25
2.2
.6
50
26
.26
.23
.27
1.5
11.8
.52
.16
.26
.16
47
-------
The average pollutant concentration for individual storms for each sub-
basin and the main gaging station are presented in Table 9. The raw
data on each sub-basin storm sample is in Appendix C. As evidenced by
Table 9, there is not much quality variation in the discharges from
individual sub-basins. The main gaging station, which represents the
entire basin, does exhibit greater concentrations of COD and solids,
assumed to be caused by the difference in sampling techniques. The sub-
basins were manually sampled, whereas the main gaging station was sam-
pled automatically.
It was concluded that the individual sub-basins within the Third Fork
Creek urban drainage basin do not exhibit significant variations in
urban runoff water quality to indicate any influence of land use on
quality of urban runoff.
Table 9. AVERAGE POLLUTANT CONCENTRATIONS FROM
SUB-BASINS DURING STORM FLOWS
Sub-basin
Organics (mg/1) - COD
TOG
BODs
Nutrients (mg/1)- K-N
Total-P
Fecal Coliforms (///ml)
Solids (mg/1) - Total
TVS
SS
VSS
Metals (mg/1) - Al
Ca
Co
Cr
Cu
Fe
Mg
Mn
Ni
Pb
Sr
Zn
E-l
93
30
60
.36
.50
540
834
202
627
102
27
2.2
<.l
.13
.11
10
16
.84
<.l
.26
<.l
.22
E-2
130
32
69
.44
.53
185
849
156
638
80
23
4.1
.1
.15
.13
6
10
.49
<.l
.13
<.l
.32
N-2
102
30
83
.57
.59
50
977
133
770
99
22
1.6
<.l
.16
.12
5
10
.51
<.l
.32
<.l
.27
W-l
95
35
36
.42
.54
242
819
132
629
87
18
1.8
<.l
.13
.10
10
7.5
1.1
<.l
.27
<.l
.32
W-2
101
32
81
.31
.57
265
938
134
739
142
23
2.0
<.l
.15
.12
13
11
.52
<.l
.25
.11
.23
Total
basin
170
42
.96
.82
230
1440
205
1223
122
16
4.8
.16
.23
.15
12
10
.67
.15
.46
.36
BOD Difficulties
The Biochemical Oxygen Demand (BOD) test is, and has been, the prime
tool of engineers and chemists in estimating the amount of potentially
biodegradable material present in a waste and the rate at which oxygen
will be utilized in a receiving watercourse. Test usage is so wide-
spread and results so universally accepted that it is sacrilegious to
48
-------
question its applicability and usefulness. However, during the proj-
ect's course, it became apparent that BOD was an inappropriate analyti-
cal test for organic characterization of urban land runoff.
All BOD analyses were run in accordance with Standard Methods (8).
Samples were not "seeded." Doubly distilled dilution water was ini-
tially used; and later, singly distilled deionized dilution water was
utilized. All tests were conducted at 20°C with a water seal.
The major difficulty encountered with the BOD test was that results
were affected by the percent stormwater of the sample. Percent storm-
water is defined as 100 times the volume of stormwater divided by the
total volume of liquid. The more dilute the sample, the greater the
BOD exerted as shown in Figures 41 and 42 which present typical varia-
tions of BOD as a function of percent dilution. It is important to
note that generally the dissolved oxygen depletion was approximately
the same in all dilutions. Consequently, BOD values appear inversely
proportional to the percent stormwater (i.e., at concentrations of 1 and
2 percent, the BOD of the 1 percent concentration is approximately
twice that of the 2 percent stormwater concentration). As different
concentrations exhibited more or less the same oxygen depletion, in
mg/1, the problem continuously arose as to which value was the "true"
value and should be reported as representing or indicating the strength
of urban land runoff. If three different concentrations met the
requirements of a minimum residual dissolved oxygen concentration of
1 mg/1 and a depletion of at least 2 mg/1, the results of the median
concentration was reported.
During the first portion of the project, concentrations of 10 and 15
percent were commonly used for 5-day BOD's. These low concentrations
produced low BOD values as compared to COD and TOG. During the remain-
der of the project, 0.5 percent, 1 percent, and 2 percent concentrations
were commonly used for BOD's, and the relative value of BOD's as com-
pared with COD and TOG were higher. This can be seen in Table 3,
giving the mean and standard deviation of organics for the 36 storms
sampled. Storm Nos. 1 through 19 were run at the lower concentrations
while 20 through 36 were run at the higher dilutions.
The exact cause for the difficulties experienced with the BOD test as
applied to urban land runoff is not known. However, the phenomena
could be due to (1) the inhibitory effect of heavy metals, (2) the
presence of other unidentified inhibitory compounds, and/or (3) inher-
ent problems of the standard BOD test.
Therefore, it is recommended that BOD not be considered an appropriate
or representative measure of pollutant strength of urban land runoff.
The BOD values presented within this report are not considered valid
and should only be utilized to assess the magnitude of problems of
associating BOD with urban land runoff. The only reason for presenting
BOD values is that they were specified as part of the work to be per-
formed under the contract and that all information gathered would be
fully reported and disclosed.
49
-------
O- 9/6/72
D - 9/21/72(A)
A - 9/21/72 (B)
O - 10/5/72
200
Ul
o
100
100
oo
a
a
50
- 9/6/72
- 9/21/72
- 10/5/72
I
12
15
12
15
X Dilution
Z Dilution
Figure 41. Typical variations of BOD with dilution.
-------
300
O - 9/6/72
A - 9/21/72 (A)
D - 9/21/72 (B)
O - 10/5/72
200
100
200
>,
S
100
O- 9/6/72
A- 9/21/72
O - 10/5/72
r i
6 9
Z Dilution
12
15
I
10 15
Z Dilution
I
20
Figure 42. Typical variations of BOD with dilution.
-------
COD Exertion Rate Studies
An important aspect of the project was to assess the impact of the urban
land runoff on a receiving stream as measured by its effect on the dis-
solved oxygen concentrations. This is normally accomplished by assess-
ing the ultimate oxygen demand of the waste and by knowing an appro-
priate exertion rate. These two values are then utilized in an oxygen
sag equation which represents the influence of the waste stream on down-
stream dissolved oxygen concentrations. The oxygen sag equation is a
relationship found in most sanitary engineering texts and as such is
known by all engineers practicing the science.
As BOD was judged an inappropriate test for determining the ultimate
oxygen demand of urban runoff, another technique should be recommended.
It is also important to provide an estimate of the exertion rate of the
new test.
To provide needed information on the total amount of biodegradable
material in urban runoff and to evaluate the exertion rate of the oxygen
demand, the following study was initiated:
Four liters of 100 percent urban runoff were placed in an
erlenmeyer flask. A stirring magnet was added and the bot-
tle placed in a dark 20°C incubation room. The four nutrients
normally added to BOD dilution water were added in the same
proportion to the four-liter samples. The stirring kept dis-
solved oxygen concentrations near saturation and the sample
homogeneous. Initial COD's (COD^) were run on each sample
and periodically during following days at time "t" (COD^).
The difference between the initial CODj and the COD of the
sample at a later time (COD^) can be assumed due to biologi-
cal activity or biodegradation of the waste. The total
amount of organic material degraded should represent the
"ultimate BOD" as supposedly given by the standard BOD test.
The COD jar test was continued until that point in time when
the CODj-COD'j' became constant indicating that all biodegrada-
tion was completed. The method of moments commonly employed
for evaluation of K]_, the BOD exertion rate constant, was
used to evaluate COD uptake. The percent of the total COD
susceptible to biodegradation was also computed.
The biodegradation in the flasks is still subject to inhibitation;
however, the COD test can be run at any strength (hopefully, full
strength) whereas the standard BOD test has to be run at several dilu-
tions. Consequently, a standard evaluation of urban runoff degradation
rate could be set at any concentration if the COD test were used,
whereas the same standard could not apply for the BOD test.
The oxygen uptake rate, K^, for urban runoff as determined by the
method of moments, as described in most sanitary engineering texts,
from BOD and COD uptake data is presented in Table 10.
52
-------
Table 10. OXYGEN UPTAKE RATES
FOR URBAN LAND RUNOFF
Sample
Urban Runoff
Secondary Sewage
Urban Runoff
Urban Runoff
Urban Runoff
Test
COD
BOD
BOD
COD
BOD
BOD
COD
BOD
BOD
BOD
COD
BOD
BOD
COD
Stormwater
concentration
CO
100
.5
1.0
100
1
5
100
1
5
5
100
2
5
100
Rate**
Kl
.08
.07
.13
.14
.20
.10
.20
.27
.27
.24
.06
.16
.20
.13
Ultimate
uptake
mg/1
106
540
190
48
125
55
98
137
112
124
20
47
30
57
Percent*
biodegradable
44
53
53
16
61
* Biodegradable COD
** Base e
Total Initial COD
One sample of secondary effluent from a municipal waste plant prior to
chlorination is also included in the table for comparison. All K-^ rates
are based solely on either BOD or COD uptake rates through 20 days,
although biodegradation in the 4-liter COD flasks continued well beyond
20 days. Figure 43 compares oxygen exertion curves as determined by
BOD and COD uptake.
The COD K-L rates for urban runoff vary from .06 to 0.20 per day while
K]_, as determined by the conventional BOD test, varies from 0.08 to
0.27. The K-, rates as determined by both techniques compare favorably
for the same sample indicating either could be used. The ultimate
amount of biodegradable material, however, appears to be dependent upon
the percent dilution. The ultimate oxygen demand in 20 days as deter-
mined from the COD tests for the 100 percent sample is always less than
that predicted by the BOD test. It appears that K-j_ is independent of
sample dilution or analysis technique whereas the 20-day ultimate
oxygen demand is dependent on sample dilution.
The rather large range in the oxygen uptake rate as predicted by either
technique is somewhat of a problem when used with an oxygen sag equa-
tion, as the sag characteristics are significantly influenced by K-^.
Oxygen uptake rates are certainly influenced by sample characteristics
which, as previously shown, vary considerably for urban land runoff.
The precise inhibitory effect of heavy metals on uptake rates is
unknown. During urban runoff events, the relative quantity of urban
runoff in Third Fork Creek was 10 to 1700 times as great as base flow.
Consequently, minimal base flow dilution was available for organics
53
-------
Dtcc: 2/26/73
•400 -
300 _
200 —
100 —
I I I I I I I I I I I I
Date: it/25/73
150 —
100
Figure 43. Oxygen exertion curves as determined by BOD and
COD uptake.
54
-------
and heavy metals. The COD uptake rate technique does allow for %
evaluation at greater concentrations than does the typical BOD test.
The percent of COD capable of biodegradation in 20 days was found to
vary from 16 to 61 percent with an average of 44 percent.
From these studies it was concluded that (1) approximately 40 to 50 per-
cent of the COD load contributed by urban runoff is susceptible to bio-
degradation in 20 days, (2) that the COD K^ exertion rate is equivalent
to that obtained by a conventional BOD test, (3) that the standard BOD
test is not an appropriate test for evaluation of urban land runoff,
and (4) that the COD test gives a reproducible value at 100% of sample
strength.
Representative Sampling
The automatic sampling device located at the USGS gaging station was
powered by a submersible centrifugal pump as previously described in the
sampling section. The pump, positioned in a perforated box, was located
approximately three feet downstream of the weir on the bottom of the
stream channel. Consequently, during runoff events the samples taken
were from the lower portion of flow in the stream. The question arose
as to the representativeness of the samples procured in relation to the
average "true" concentration of pollutants at any given time. The
velocity profile in a natural channel is well known; and consequently,
pollutant concentration variations should be expected. In an attempt
to define the magnitude of the pollutant variations within the cross-
sectional flow, samples were obtained manually at the surface of the
stream during three separate storms at the same time the automatic
sampler was procuring its sample.
The average pollutant concentration at just below the water's surface
is compared with the average pollutant concentration of the correspond-
ing samples obtained by the automatic sampler in Table 11. As can be
seen in the table, the concentrations of pollutants were almost always
greater for samples obtained automatically adjacent to the bottom than
they were at the surface. The COD concentration adjacent to the sur-
face is 67 percent of that obtained at the bottom. It is apparent that
at least two important profiles exist in Third Fork Creek, a velocity
profile and a pollutant profile.
Pollutant Regression Equations
In order to describe pollutant concentration variations within storms
and to assess the annual pollutant yield of urban runoff, analytical
data from the 36 storms sampled were used to determine appropriate
regression equations relating yield to runoff characteristics. The
independent variables used were rate of runoff (CFS), time from storm
start (TFSS) in hours, time from last storm (TFLS) in hours, and time
from last peak (TFLP) in hours.
Initially, all four independent variables were used for regression to
determine which were significant in describing pollutant yield
55
-------
Table 11. COMPARISON OF POLLUTANT CONCENTRATIONS ADJACENT TO WATER'S
SURFACE WITH THOSE OBTAINED BY AUTOMATIC SAMPLER
COD
TOC
BOD5
K-Nitrogen
Total Phosphorus
Fecal Coliform (///ml)
Total Solids
Volatile Solids
Total Sus. Solids
Volatile Sus. Solids
Calcium
Chromium
Iron
Magnesium
Manganese
Lead
Zinc
Surface
concentration
150
40
62
.4
.78
348
1413
269
1156
142
1.76
.15
10.7
8.8
.81
.24
.34
Automatic
sampler
concentration
233
53
62
.4
.90
427
2976
321
2611
211
1.69
.18
14.8
9.8
1.11
.31
.45
Surface concentration
as a % of automatic
sampler concentration
67
75
100
100
87
81
47
84
44
67
104
83
72
90
73
77
76
variations within storm events. As a result, it was found that the
rate of discharge (CFS) and time from storm start (TFSS), as indicated
by runoff initiation, in hours were the two most significant variables.
Only a modest gain in the correlation coefficient, r2, was realized with
the additional two time variables. It was decided to limit the regres-
sion equations to CFS and TFSS for regression simplicity.
Prior opinion would indicate that TFLS should be a significant factor,
the more frequent runoff events are the less the buildup time for
pollutants on an urban watershed. However, for the Third Fork Creek in
Durham, North Carolina, the frequency of runoff events did not appear
to influence significantly the pollutant discharge from the basin.
The final regression equations describing urban runoff pollutant flow
in pounds per minute as a function of CFS and TFSS are presented in
Table 12 with the corresponding correlation coefficients.
The COD values for Storm Nos. 1 and 2 were excluded from the analysis
as the samples were obtained manually instead of by the automatic
sampler. The kjeldahl nitrogen values for Storm Nos. 3 and 4 were
excluded as the results were considered atypical.
The regression equations as presented in Table 12 can be adjusted to
produce equations relating pollutant concentration in mg/1 to rate of
flow and time from storm start. The regression equations may also be
adjusted to reflect concentrations at mid-depth. The equation relating
COD in pounds per minute as a function of CFS and TFSS is:
56
-------
Table 12. EQUATIONS DESCRIBING URBAN RUNOFF POLLUTANT FLUX NEAR
CHANNEL BOTTOM IN POUNDS PER MINUTE FOR DURHAM, NORTH
CAROLINA, AS A FUNCTION OF DISCHARGE RATE (CFS) AND
TIME FROM STORM START (TFSS) IN HOURS
Equation
R
111 — ?S
COD = 0.51 CFS TFSS
TOG = 0.16 CFS1'0 TFSS~'28
Total Solids =3.35 CFS1'14 TFSS~'18
Volatile Solids =0.58 CFS1'09 TFSS"'11
Suspended Solids = 1.89 CFS1'23 TFSS~'16
Volatile Suspended Solids =0.25 CFS1'18 TFSS~'17
87 - 29
Kjeldahl Nitrogen = 0.0032 CFS' TFSS '
1 03 — 29
Total Phosphorus as P = 0.003 CFS TFSS *
Aluminum = 0.0443 CFS1'05 TFSS~<15
Calcium = 0.045 CFS°'6° TFSS~'°9
Cobalt = 0.0003 CFS1'18 TFSS+'13
Chromium = 0.0008 CFS'96 TFSS+°'°
Copper = 0.00035 CFS1'10 TFSS+'°8
Iron = 0.0238 CFS1'24 TFSS~'18
1125 - 29
Lead = 0.0013 CFS TFSS '
Magnesium = 0.0434 CFS' TFSS~'
Manganese = 0.0023 CFS1'11 TFSS~'
Nickel = 0.0005 CFS1'03 TFSS+- 1
Zinc = 0.0011 CFS1'10 TFSS~'22
.90
.84
.85
.92
.76
.83
.73
.92
.89
.82
.92
.89
.94
.87
.83
.94
.94
.94
.89
57
-------
COD = 0.51 CFS1'11 TFSS °'28
where COD is in pounds per minute
CFS is cubic feet per second
and TFSS is time in hours from the initiation
of runoff.
The equation may be adjusted to reflect concentrations at average depth
with the use of a correction factor derived from information contained
in Table 11. The correction factor for COD is 0.835; i.e., (1 + .67)
v 2. This yields the equation:
1 1 ~\ — ?ft
COD = .425 CFS TFSS '
To modify the COD equation to reflect mg/1 COD as a function of CFS and
TFSS, the relationship is:
,., 267 Ibs/min
mg/1 =
The regression equation, therefore, becomes:
Oil — ?fi
COD = 113 CFS TFSS '
where COD is in mg/1 at average depth.
All regression equations in Table 12 may be adjusted accordingly to give
pollutant concentration in mg/1 in a natural channel at mid-depth flow
and are as presented in Table 13 .
Figures 44 through 46 present variations in pollutant concentrations as
a function of CFS and TFSS as predicted by adjusted regression equations
for a typical storm hydrograph.
Annual Pollutant Yield
Data from each runoff event occurring during the 1972 calendar year were
obtained from the discharge records of the Third Fork Creek gaging sta-
tion. For each of the 66 storms occurring during the year discharge
rates were determined at 30-minute intervals. These rates and the time
from storm start were used to find the pollutant yield in pounds per
acre per year as a result of urban runoff.
The annual pollutant yield of urban runoff is composed of pollutants
contributed during base flow periods and storm periods. As illustrated
in Table 11, the average pollutant concentration taken by the automatic
sampler was in most cases higher than the corresponding concentrations
at the water's surface. Consequently, the total pounds predicted by the
regression equations based on data from the automatic sampler are
adjusted to reflect the concentrations at mid-depth, assuming a linear
58
-------
Table 13. REGRESSION EQUATIONS PREDICTING POLLUTANT CONCENTRATION
(MG/L) IN URBAN LAND RUNOFF IN A NATURAL CHANNEL
CORRECTED TO FLOW AT MID-DEPTH*
Pollutant
COD
TOC
TS
TVS
TSS
VSS
Kjel. N.
Total P.
Al**
Ca
Co**
Cr
Cu**
Fe
Pb
Mg
Mn
Ni**
Zn
mg/1
113.
32.
420.
130.
222.
44.
0.85
0.80
10.
12.5
0.07
0.18
0.08
4.6
0.27
10.
0.45
0.12
0.22
CFS0-11 TFSS °
CFS°-° TFSS~-
014
CFS TFSS '
CFS°-°9 TFSS~"
CFS0-23 TFSS'-
0 1 R
CFS TFSS '
0 87
CFS TFSS '
CFS0'03 TFSS~"
CFS°-°5 TFSS —
-.4
CFS TFSS
CFS°-18 TFSS+'
- . 04 + .
CFS TFSS
CFS0'10 TFSS+"
CFS0'24 TFSS—
CFS0-125 TFSS"
-.02
CFS TFSS
CFS0'11 TFSS'
CFS0-03 TFSS'
0.10
m^c T'PCO
L.r o J. ro k>
.28
28
18
11
16
17
29
29
15
09
13
06
08
18
-.29
16
27
01
22
* CFS - Cubic Feet Per Second
* TFSS = Time from Storm Start (Hours)
**Mid-depth Correction Assumed as 0.9.
59
-------
300
250
COD
TOC
200
150
100
50
s
v
E
1.5
\
Totfll Phosphorus
Lead
K- Nitrogen
Chromium ••••••
Figure 44.
100
75
50
Tim«, Hr».
Pollutant concentrations in mg/1 for a typical
storm hydrograph as predicted by adjusted
regression equations.
60
-------
1200
Total Solid!
Total Suiptndtd Solids-
Volatile Solid*
Volotll* Sutptndid ••••
900
5 600
300
Aluminum
I ron
Time, Mrs.
_ 100
Figure 45.
Pollutant concentrations in mg/1 for a typical
storm hydrograph as predicted by adjusted
regression equations.
61
-------
0.20
0.15
x
e»
~ O.I
o
o
0.05
I .2
x
CT
E
o .6
.3
Mangdnese
Zinc
100
75
50
25
Time, Mrs.
Figure 46. Pollutant concentrations in mg/1 for a
typical storm hydrograph as predicted
by adjusted regression equations.
62
-------
vertical distribution. The average COD at the surface was 67 percent of
that at the bottom. Therefore, a more correct estimate of the pollutant
yield assuming a linear variation would be 83.5 percent [(100 + 67) ^2]
of that predicted by the regression equations. The annual yield of
pollutants from urban runoff in pounds/aere/year for the urban Third
Fork study area is presented in Table 14. During the 1972 calendar year,
base flow existed 7080 hours or 81 percent of the time, while runoff
from the 66 storms required 1680 hours or 19 percent of the time.
Table 14. ESTIMATED 1972 POLLUTANT YIELD FOR THIRD FORK
CREEK DRAINAGE BASIN IN POUNDS/ACRE/YEAR
Pollutant
COD
TOG
Total Solids
Volatile Solids
Suspended Solids
Volatile Sus. Solids
Kjeldahl Nitrogen as "N"
Total Phosphorus as "P"
Aluminum
Calcium
Cobalt
Chromium
Copper
Iron
Magnesium
Manganese
Nickel
Lead
Zinc
Urban Runoff
Predicted
1071
190
9660
1440
9190
910
2.8
4.1
76
14
1.7
1.4
1.3
118
57
4.9
1.1
2.8
2.1
Correction
factor
.835
.875
.735
.92
.72
.835
1.0
.935
.90**
1.02
.90**
.915
.90**
.86
.95
.865
.90**
.885
.88
Adjusted
j-ield
895
166
7100
1324
6617
760
2.8
3.8
63
14
1.5
1.3
1.2
100
54
4.2
1.0
2.5
1.8
Base
flow
43
21
600
134
74
37
3.3
.9
1.5
38
0.4
.3
.4
2.2
17
.7
.2
.4
.2
Annual
yield*
938
187
7700
1458
6691
797
6.1
4.7
64
52
1.9
1.6
1.6
102
71
4.9
1.2
2.9
2.0
* Annual Yield = Base Flow + Adjusted Yield
** Correction Factor Estimated
Summary
The objective of this portion of the project was the characterization of
urban land runoff in Durham, North Carolina, with emphasis on correla-
tion of stormwater quality variations with respect to the rate of flow,
storm characteristics, runoff time, and land use.
Thirty-six storms were sampled during the project period through the use
of an automatic sampler. Pollutant concentrations were found to vary
significantly throughout runoff events and from storm to storm. For
most pollutants the standard deviation was approximately 70 to 80 per-
cent of the mean. Pollutant concentrations during the rising limb of
the hydrograph were typically higher than those during the remaining
hydrograph, indicating a first-flush effect.
63
-------
Five times during the study storms were manually sampled at sub-basin
discharge locations to determine the effect of varying land-use quali-
ties with the quality of urban land runoff. The mean pollutant concen-
trations from each of the sub-basins were approximately equal, thus
indicating little relationship between land use and urban land runoff
quality in Durham, North Carolina.
Difficulties with the standard Biochemical Oxygen Demand (BOD) test
during the project period led to the conclusion that it was not an
appropriate test for evaluation of the organic concentration of urban
land runoff.
A technique utilizing the uptake of Chemical Oxygen Demand (COD) to
estimate the ultimate amount of organic material susceptible to bio-
degradation in 20 days indicated that approximately 40 to 50 percent of
the COD was capable of biodegradation.
The K-^ (base e) oxygen demand rate for urban land runoff was found to
vary from .06 to 0.27 per day, indicating the demand rate is approxi-
mately the same as the effluent from a secondary treatment plant.
Substantial pollutant concentration variations were found to exist
vertically in the stream channel during runoff events with higher con-
centrations increasing with depth.
Regression equations were developed for each pollutant relating pollu-
tant flux in pounds/minute as a function of the rate of discharge and
lapse of time as measured from the start of the rising limb of the run-
off hydrograph. The time since the last storm was not found to be a
significant factor affecting the quality of urban land runoff in Durham,
North Carolina. These equations may be adjusted to reflect pollutant
concentrations in mg/1 and to reflect concentrations at mid-depth.
The annual pollutant yield in pounds per acre of drainage basin during
the 1972 year was calculated from the 66 storms occurring during the
year. The regression equations were utilized with an appropriate
factor to correct for vertical variations of pollutant concentrations
with depth of flow.
64
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SECTION VII
CHEMICAL-PHYSICAL TREATMENT STUDIES
Introduction
One aspect of the project was investigation and evaluation of the appli-
cability, effectiveness, and economics of physical-chemical treatment of
urban runoff by coagulation and sedimentation.
The flow rate variations of urban runoff are substantially different
from the flow rate variations encountered at sewage treatment plants.
Urban stormwater is an intermittent source of large flows whereas muni-
cipal waste is typified by continuous discharge at a relatively constant
rate. A widely varying intermittent input is not conducive to effective
biological treatment because micro-organisms require continuous feeding
with minor variations in input quantity. It appears that a physical
and/or chemical removal process for treatment of urban runoff is the
most appropriate.
Once it is established that urban runoff should be treated in a given
area, the next step is evaluation of the unit process pollutant removal
efficiency of various treatment methods. Only by determining the most
efficient and economical treatment method will the public ba assured of
maximum return on its investment.
One physical-chemical treatment method which might be considered is
coagulation. Coagulation is the process by which "like-charged"
colloidal particles in solution are agglomerated by one or a combination
of phenomena into a particle of such weight and size that it will settle
by itself. Colloids found in wastewaters are typically negatively
charged. The electric properties of these particles tend to keep them
in solution in a colloidal state. Two opposing forces affect their
relative behavior. The Van der Waals force tends to draw them together
while the electrostatic repulsive force tends to keep them apart.
Van der Waals attractive force varies inversely as the square of the
distance between the two particles, while the "like-charge" repulsive
force decreases exponentially with distance. Only if the kinetic energy
of the relative particles is strong enough to overcome the repulsive
force to where Van der Waals attractive force predominates, will the
colloidal particles coagulate.
Coagulation of a waste may result from two basic phenomena or mecha-
nisms: perikinetic coagulation in which the zeta potential or surface
charge of the colloids is reduced by ions of opposite charge to levels
below those of Van der Waals attractive force and thus coagulate; or
orthokinetic coagulation in which the colloidal particles become trapped
on, enmeshed in, or adsorbed by precipitate or "sweep floe" formed by
metal hydroxides. Flocculation by organic polyelectrolytes may occur by
particle adsorption creating a large blanket of polymer floe which set-
tles, removing trapped particles as it subsides.
65
-------
O'Melia (5) has described the relationship between the initial colloid
concentration and coagulant dosage. For wastes with low initial colloid
concentration, a low probability of particle contact exists whereas for
high colloid concentrations the reverse is true. Therefore, for coagu-
lation to occur at lower colloid concentration, the presence of addi-
tional metal hydroxide precipitate is required, as removal will occur
primarily by orthokinetic coagulation; i.e., particles are caught by the
large settling mass of precipitates. At higher colloid concentrations,
a smaller dosage of coagulant is required, as colloids may be removed
primarily by the perikinetic coagulation process. Consequently, the
optimum dosage of coagulant will vary depending upon the initial col-
loid concentration of each sample and with time. The concentration of
colloids in stormwater was found to have a high initial concentration
indicating that perikinetic coagulation was the predominate phenomena
that would occur in chemical treatment of urban stormwaters.
The alkalinity of the waste to be treated plays an important role in the
efficiency of the process and the required coagulant dosage, as neutrali-
zation of the negatively charged colloids occurs by increasing the
amount of positively charged cations, metal complexes, etc. that are
prevalent at lower pH's. Alkalinity indirectly provides buffering
capacity, making a waste more resistant to pH changes from the addition
of metal coagulants such as Al+^. The addition of Alum forms compounds
such as
Al+3 + 4H20 -> A1(OH)4~ + 4H+
which tend to produce excess hydrogen ions tending to lower the pH. The
greater the alkalinity, the greater the buffering effect and the greater
the addition of alum required to lower the pH to the isoelectric point
of the colloid in question.
The range of alkalinities in mg/1 as CaCC>3 found in urban runoff in
Durham varied from 40 to 120, with an average of approximately 80 mg/1,
indicative of relatively low alkalinities.
The combination of high colloid concentration and low alkalinity is,
according to O'Melia, the easiest system to treat as only optimum coagu-
lant dosage needs to be determined. Destabilization of the colloids is
best achieved by positively charged hydrometal complexes produced in
acidic ranges.
Jar Test Procedure
The complex chemical reactions involved in coagulation necessitated
extensive laboratory experimentation to evaluate optimum conditions for
effective pollutant removal. The parameters studied included optimum
dosage and pH. Coagulants were evaluated in terms of removal of COD,
suspended solids, and turbidity.
Composite urban runoff samples were procured at the main gaging site in
5-gallon, polyethylene containers and were stored at 3CC prior to usage.
66
-------
A 6-paddle Phipps and Bird jar test apparatus was utilized to determine
optimum pH and coagulant dosage. The jar test procedure followed was:
1. Determination, of initial coagulant dosage. A one-liter sample
was placed on a magnetic stirrer and adjusted to a pH of 6
by the addition of a strong acid or base. Coagulant was added
in small doses and flash mixed for one minute followed by
three minutes of slow mix. This procedure was continued with
successively greater concentrations of coagulant until a visi-
ble floe was formed.
2. One liter of sample was placed in each of six 1500 ml beakers
and the pH in each beaker was so adjusted as to give a pH
range of from 4 to 9 by the addition of a strong acid or base.
3. The coagulant dosage as determined in step (1) was added to
each beaker.
4. Each sample was rapid mixed at 80 RPM for 3 minutes, floccu-
lated at 20 BPM for 12 minutes, and allowed to settle under
quiescent conditions for 15 minutes.
5. Samples of supernatant from each of the six beakers were
analyzed for COD, suspended solids, and turbidity. Sludge
characteristics were observed visually.
6. Optimum pH was selected on the basis of supernatant pollutant
removal.
7- Steps 2, 4, and 5 were repeated utilizing the optimum pH as
determined in step 6 with a varying coagulant concentration
in each beaker.
8. Optimum coagulant dosage for optimum pH was chosen on basis
of pollutant removal as in step 6.
Coagulants Evaluated
The coagulants evaluated included:
1. Inorganic
• Alum
• Ferric chloride
• Ferrous chloride
• Lime
2. Organic
• Anionic
DOW - A-22 and A-23
• Non-ionic
DOW N-ll and N-17
• Cationic
DOW C-31, C-32, C-41 and ET-721
Calgon WT-2660, ST 2870 and WT-3000
67
-------
3. Combinations of the preceding
4. Montmorillonite clay and Calgon Aid 18 as coagulant aids
Coagulant Evaluation
A one-liter sample of raw waste was allowed to settle quiescently for
15 minutes during each jar test, without pH adjustment or coagulant
addition, to assess the pollutant removal efficiency of sedimentation
alone. Supernatant samples were analyzed to determine the percent
reduction of COD, suspended solids, and turbidity as compared to a raw
mixed sample.
Graphs describing percent removal of suspended solids, COD, and tur-
bidity as a function of pH were developed for each test to determine
the pH producing optimum removal efficiency for a fixed coagulant dos-
age. Representative graphs showing the effect of pH on removal effi-
ciencies for alum, Dow's C-32 and Dow's A-21 are presented in Figures
47, 48, and 49. The optimum pH as recorded indicates the initial pH
prior to coagulant addition. The final supernatant pH after coag-
ulation, flocculation, and settling was not necessarily the same. In
the case of alum, supernatant pH after treatment was approximately
4.5 - 6.4 whereas initial pH was 6-8. In the case of lime, initial
pH was 6-8, whereas final supernatant pH was 9 to 11, depending on
the amount of lime added. The final supernatant pH of the organic
polyelectrolytes did not vary significantly from the initial pH. The
removal efficiencies of the anionic and non-ionic polyelectrolytes
appeared to be less dependent on pH than metal salts or cationic
polyelectrolytes.
After selection of optimum pH, varying doses of coagulant addition were
evaluated to determine the optimum dose corresponding to the optimum pH.
One liter of raw waste samples were again allowed to settle without pH
adjustment or coagulant addition to evaluate the pollutant removal
efficiency of plain settling. Supernatant from the six jars of varying
dosage were analyzed to determine the removal of COD, suspended solids,
and turbidity. A graph showing the percent removal of each pollutant
versus dosage at optimum pH was constructed. Figures 47, 48, and 49
give representative removal efficiencies of alum, Dow's C-32, and
Dow's A-21 as a function of dosage at the optimum pH.
Complete information on all runs for each coagulant evaluated is pre-
sented in Table 15. Included in this table is the optimum pH, optimum
coagulant dosage, and the initial sample concentration of COD, sus-
pended solids, and turbidity. The removal efficiency of each pollutant
by plain sedimentation for each jar test is given. The total percent
removed by chemical coagulation and settling is presented. The
residual removal efficiency of each coagulant is also presented and is
defined as that percent of the residual pollutant concentration not
removed by plain sedimentation that was removed only because of coagu-
lant usage. The coagulant residual removal efficiency indicates the
specific gain to be realized in pollutant removal over plain settling
and compares the relative benefits of individual coagulants.
68
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OPTIMUM pH DETERMINATION
100
80
60
40
A - Suspended Solids
O - COD
D - Turbidity
Dosage 50 mg/l
I
10
60 £
•o
a
40 £
20
pH
OPTIMUM DOSAGE DETERMINATION
100
60
60
40
I
55
— Suspended Solids
O - COD
D Turbidity
pH - 8
I
60
I I
65 70
Dosage mg/l
-O-
I
75
I
80
300 .-
200 "2
100
Figure 47. Determination of optimum pH and dosage for alum.
69
-------
OPTIMUM pH DETERMINATION
100
eo
60
40
20
-Cr
£>— Suspended Solids
O - COD
O - Turb idity
Dosage 10 mg/l
80
60
20
T r
OPTIMUM DOSAGE DETERMINATION
100
80
60
40
20
A - Suspended Sol Ids
O - COD
O - Turbidity
pH 7
I
10 12
Dosage mg/l
14
100
80
60
40
20
16
Figure 48. Optimum pH and dosage determination for Dow's C-32.
70
-------
OPTIMUMpH DETERMINATION
E
a.
100
80
60
40
20
100 —
a - coo
& - Turbidity
Doing* = 10 mg/l
i r
PH
OPTIMUM DOSAGE DETERMINATION
50
30
20 I
to
O
O
E
£ 60
ss
40
20
Q - COD
& - Turbidity
pH - 7.1
—
£. ~
^y~ cs " "
— -
-
3
•"
30 |
1
20
O
^
1
10 ^
1 1 1 1 1 1
4 6 8 10 12 14
Dosage mg/l
Figure 49. Determination of optimum pH and dosage for Dow's A-22,
71
-------
Table 15. INDIVIDUAL JAR TEST RESULTS AT OPTIMUM pH AND DOSAGE
Coagulant
Inorganics
Alum
Ferric
Chloride
Ferrous
Chloride
Lime
Run
Number
8
38
39
43
48
64
7
9
35
36
37
45
10
65
66
5
64
67
Op timum
pH
6.0
8.0
7.0
8.0
8.0
7.3
AVERAGE
9.0
11.0
11.0
11.0
12.0
11.0
AVERAGE
11.0
6.8
6.9
AVERAGE
4.0
6.9
6.9
AVERAGE
Dosage mg/1
Range
20-70
55-80
20-45
45-70
20-45
40-70
20-70
5-30
6-16
18-28
16-26
10-35
10-60
30-80
200-300
20-45
80-180
80-180
Optimum
60
75
35
70
45
40
54
20
25
16
26
22
35
24
30
80
300
137
45
160
160
122
Raw Sample Concentration
COD
mg/1
155
187
119
285
227
55
171
309
113
102
99
232
219
179
121
251
390
254
290
322
306
S.S.
mg/1
420
2120
616
1534
310
324
887
250
138
370
552
508
221
340
294
654
1018
655
102
700
1612
805
Turbidity •
JTU
753
325
753
225
342
480
159
495
700
216
392
100
303
680
361
286
680
483
% Removal by
Settling Only
COD
47
41
65
79
46
21
50
47
42
57
55
86
75
60
52
61
91
68
64
88
76
S.S.
89
80
37
65
87
30
65
82
85
80
80
85
82
82
88
71
88
82
83
77
87
82
Turbidity
61
38
22
56
22
40
46
56
24
61
47
79
17
39
45
15
39
27
% Removal by
Coagulation
COD
80
93
88
97
64
75
82
67
60
76
82
9?
86
77
75
84
90
83
87
97
92
S.S.
99
100
89
100
98
87
97
83
94
90
63
87
99
86
100
97
96
98
99
98
98
98
Turbidity
98
83
99
97
97
94
81
67
63
94
76
97
83
78
86
96
92
94
Residual Removal
Efficiency (Z)
COD
62
88
66
85
33
68
67
38
31
44
60
43
44
43
48
59
0
36
64
75
69
S.S.
91
100
82
100
85
81
90
5
60
50
0
.13
94
37
100
90
67
86
94
91
85
90
Turbidity
95
72
99
93
96
91
65
25
51
85
56
86
79
64
76
95
87
91
(Continued)
-------
Table 15 (continued). INDIVIDUAL JAR TEST RESULTS AT OPTIMUM pH AND DOSAGE
Coagulant
Organica
Dow C31
Dow C32
Dov C41
Dow A22
Dow A23
Dow N17
Dow Nil
Calgon 2661
Run
Number
11
13
25
26
27
54
12
14
15
29
31
57
20
16
17
18
19
24
40
41
55
Optimum
pH
7.0
6.0
6.8
6.6
6.8
6.9
AVERAGE
7.2
6.0
7.4
6.8
7.0
6.8
AVERAGE
4.0
7.1
4.0
6.8
6.8
6.9
7.2
7.3
6.8
AVERAGE
Dosa
Range
6-16
14-24
10-20
4-14
6-16
4-14
14-24
20-120
10-20
6-16
20-45
4-14
1-6
6-16
10-20
10-20
10-20
4-14
ge mg/1
Optimum
14
24
10
12
14
20
16
8
20
20
16
16
20
17
20
10
5
6
10
10
10
8
20
12
Raw Sample Concentration
COD
mg/1
104
112
116
510
173
129
191
119
108
349
112
497
244
238
125
374
146
129
145
997
111
25
263
349
S.S.
mg/1
122
386
470
1026
826
156
498
152
160
570
516
1258
464
520
1456
356
1130
88
26
264
377
Turbidity
JTU
104
269
302
395
512
243
304
71
398
260
264
412
495
317
343
361
274
435
414
413
113
85
243
213
% Removal by
Settling Only
COD
45
51
69
84
83
67
66
38
49
68
42
76
36
51
91
83
76
75
80
90
77
1
25
48
S.S.
84
74
79
90
77
52
76
92
51
91
79
87
68
78
95
95
97
33
61
48
60
Turbidity
75
1
41
72
63
51
50
91
32
55
38
63
60
56
52
78
26
48
47
81
15
22
27
36
% Removal by
Coagulation
COD
47
83
93
92
93
73
80
56
89
85
70
90
56
74
99
85
86
77
82
92
88
2
47
57
S.S.
81
98
99
98
99
52
88
91
97
97
94
99
92
95
96
84
100
24
94
90
77
Turbidity
88
93
95
95
95
65
88
80
97
95
85
96
93
91
89
93
43
66
64
98
73
81
91
86
Reslaual Removal
Efficiency (X)
COD
4
65
77
50
59
18
45
29
78
53
48
58
31
49
89
18
38
8
10
20
48
1
29
24
S.S.
0
92
95
80
97
0
61
0
94
67
71
92
75
66
20
0
43
0
85
81
52
Turbidity
52
93
91
82
86
28
72
0
95
89
76
89
82
72
77
68
23
35
32
89
68
76
88
80
(Continued)
-------
Table 15 (continued). INDIVIDUAL JAR TEST RESULTS AT OPTIMUM pH AND DOSAGE
Coagulant
Calgon
2870
Calgoo
3000
Run
Number
21
23
32
56
22
Optimum
pH
6.7
4.0
6.9
6.8
AVERAGE
6.8
Dosage mg/1
Range
8-18
10-20
8-18
10-20
Optimum
18
10
18
20
16
10
Raw Sample Concentration
COD
mg/1
112
543
507
252
353
496
S.S.
mg/1
558
438
1150
276
605
Turbidity
JTU
417
413
413
263
376
447
COD
87
80
74
12
63
82
% Removal by
Settling Only
S.S.
86
96
84
36
75
Turbidity
34
84
65
54
59
85
H Removal by
Coagulation
COD
96
84
87
-50
79
81
s.s.
97
98
100
98
98
Trubidity
94
94
88
94
92
85
Residual Removal
Efficiency (Z)
COD
69
20
50
43
45
0
S.S.
78
50
100
97
81
Turbidity
91
62
66
87
76
0
-------
Initially, all coagulants were evaluated once to determine those coagu-
lants showing promise. After the initial evaluation, additional jar
tests were performed on the coagulants believed to be most efficient.
The organic coagulants were found to be relatively independent of pH in
most cases and had COD values themselves. Consequently, it was impos-
sible to determine what portion of the residual supernatant COD was
directly attributable to the organic coagulant.
The coagulants selected for additional jar testing were alum, lime,
ferric chloride, Dow's C-31 and C-32, and Calgon's WT-2660 and WT-2870.
The results of these additional evaluations of optimum pH and dosage are
also included in Table 15.
Coagulant Aid Evaluation
After evaluating the removal efficiencies of the individual coagulants
and selecting those with promising removal efficiencies, a study of the
use of various coagulant aids was initiated to determine if the addition
of coagulant aid with alum, ferric chloride, Dow's C-31, Dow's C-32,
Calgon's 2660 and 2870 would bring about increased removal efficiencies
by the primary coagulant.
Complete jar tests, including determination of optimum pH and coagulant
aid doses, were made with prior addition of the optimum dose of the
primary coagulant as previously determined. The coagulant aids eval-
uated with alum and ferric chloride were Calgon Aid 18, Dow's C-32, and
Calgon's 2870. The coagulant aids evaluated for use with the cationic
polyelectrolytes included Calgon Aid 18 and montmofillonite clay. One
liter of raw sample was again allowed to settle without any pH adjust-
ment or coagulant addition for 15 minutes to evaluate the removal effi-
ciency of plain settling. Table 16 gives optimum coagulant aid dosage,
optimum pH and associated COD, solids, turbidity removals for coagula-
tion and the residual efficiency of each coagulant aid combination for
each jar test.
Coagulant Selection
The average COD removal efficiency for 15 minutes of ideal quiescent
settling for 53 observations was 61 percent with a range from 1 to 91
percent. Average suspended solids removed by quiescent settling was 77
percent with a range from 33 to 95 percent, while the average turbidity
removal was 53 percent from settling alone with a range from 1 to 91,
percent.
The wide range of removal efficiencies for plain sedimentation was due
to variations in quality of the raw sample as shown by the characteri-
zation of urban runoff with respect to these specific contaminants.
Not all jar tests could be run immediately after sample procurement as
the tests are very time consuming. An average run of optimum pH and
dosage with six jars each, with duplicate COD's, suspended solids, and
turbidity easily took one man a week including preparation and analysis.
Consequently, sample characteristic changes could have occurred as a
75
-------
Table 16. INDIVIDUAL JAR TEST RESULTS FOR COAGULANT AIDS
Coagulant
Plus Coagulant
Aid
45 mg/1 Alum
plus :
Calgon Aid 18
Dow C-32
Calgon 2870
Mont. Clay
35 mg/1 Ferric
Chloride plus:
Calgon Aid 18
Dow C-32
Calgon 2870
20 mg/1 C31
plus:
Montmt. Clay
Calgon Aid 18
20 mg/1 C32
plus:
Calgon Aid 18
Mont. Clay
20 mg/1 Calgon
2660 plus:
Mont. Clay
Mont. Clay
20 mg/1 Calgon
2870 plus:
Mont. Clay
Mont. Clay
Run
Number
51
50
49
65
52
47
46
28
58
30
61
59
63
60
62
Coagulant Aid
Dosage
Range
4-14
2-10
2-12
5-25
4-14
2-10
1-10
10-18
4-20
6-16
4-20
4-20
8-16
4-20
12-20
Optimum
14
4
8
15
8
8
1
14
20
16
20
12
16
16
12
Optimum
pH
8.0
8.0
8.0
7.3
11.0
11.0
11.0
6.8
6.9
6.8
6.8
6.8
7.3
AVERAGE
6.8
7.3
AVERAGE
Raw Sample Concentration
COD
mg/1
136
134
219
55
190
166
160
79
129
74
244
263
55
159
252
55
153
S.S.
Bg/1
508
356
328
324
246
516
366
338
156
438
464
264
324
294
276
324
300
Turbidity
JTU
225
198
248
342
181
207
225
342
243
445
495
243
342
292
263
342
302
% Removal by
Settling^Only
COD
66
56
45
21
50
60
76
56
67
55
36
25
21
23
12
21
16
S.S.
85
73
68
30
80
79
70
80
52
93
68
48
30
39
36
30
33
Turbidity
65
87
59
22
76
62
68
68
51
76
60
27
22
24
54
22
38
% Removal by
Coagulation
COD
91
88
66
75
66
81
85
80
93
79
62
50
75
62
48
61
54
S.S.
99
95
99
87
98
96
92
95
52
99
98
96
96
96
99
92
95
Turbidity
99
97
98
97
93
98
89
96
85
97
98
95
96
95
95
89
92
Residual Removal
Efficiency (Z)
COD
73
72
38
68
32
52
37
54
79
53
41
33
68
50
41
51
46
S.S.
93
81
97
81
90
81
73
75
0
86
94
92
94
93
98
88
98
Turbidity
97
77
95
96
71
95
66
87
69
87
95
93
95
94
89
: 86
87
-------
result of storage, even though samples were stored at 3°C and completely
mixed prior to usage.
The relative advantages of a coagulant should be evaluated on the
characteristic residual removal efficiency as this parameter reflects
the relative ability of a specific coagulant to remove that fraction of
the pollutant load not susceptible to removal by plain sedimentation.
The coagulants evaluated are ranked according to the average residual
removal efficiency of COD, suspended solids, and turbidity in Table 17.
The removal efficiency of plain sedimentation used to construct the
table are those for the particular run in question and not the average
of all the sedimentation tests.
Table 17. COAGULANT RANKING ON AVERAGE RESIDUAL REMOVAL EFFICIENCY
OF,COD, SUSPENDED SOLIDS, AND TURBIDITY
Rank
1
2 (
(
4
5
6 (
(
(
(
10 1
(
12
13
14
15
16 (
(
18 1
(
20
21
22
23
24
25
26
27
Coagulant
Alum + Calgon Aid 18
Alum
Lime
Alum + Montmorillonite Clay
Calgon 2660 + Montmorillonite Clay
Calgon 2870 + Montmorillonite Clay
Alum + Dow C-32
Alum + Calgon 2870
Dow C-32 + Montmorillonite Clay
Ferric Chloride + Dow C-32
Dow C-32 + Calgon Aid 18
Dow C-31 + Montmorillonite Clay
Calgon 2870
Ferrous Chloride
Ferric Chloride -t- Calgon Aid 18
Dow C-32
Dow C-41
Dow C-31
Ferric Chloride + Calgon Aid 18
Calgon 2660
Dow C-31 + Calgon Aid 18
Ferric Chloride
Dow A-22
Dow A- 2 3
Dow N-17
Dow N-ll
Calgon 3000
Average residual
removal efficiency (%)
88
83
83
82
79
77
77
77
77
76
76
72
67
66
64
62
62
59
59
52
49
45
40
32
22
14
0
Alum, with and without Calgon Aid 18 and montmorillonite clay, was
judged the most effective coagulant. At optimum conditions, total
removals of COD, suspended solids, and turbidity of 84, 97, and 94 per-
cent, respectively, were realized with an average residual removal
77
-------
efficiency as previously defined of 82-88 percent over plain sedimenta-
tion. The supernatant had a very clear appearance, and the floe set-
tled easily. The optimum and final pH was approximately neutral, thus
requiring no pH adjustments. Alum also has the advantage of being
readily available, relatively inexpensive, good storage characteristics,
non-toxic, and easily applied.
Iron salts, with and without aids, was less effective than alum. The
optimum pH of 9 to 11 would require the use of a strong base to achieve
the optimum pH and the use of a strong acid to reduce the pH prior to
discharge to the receiving watercourse. Iron salts left a residual
turbidity and characteristic iron color in the supernatant.
Lime produced an average' total removal of COD, suspended solids, and
turbidity of 92, 98, and 94 percent and had an excellent residual
removal efficiency of 83 percent. "Lime, like alum, provided a clear
supernatant with good floe characteristics. The high lime dosage at
the optimum pH, however, left the supernatant with a pH of approximately
10 which would require the use of a strong acid prior to release to a
receiving watercourse. The optimum lime dose in mg/1 was higher than
that for alum.
Cationic polyelectrolytes in general were associated with good removal
efficiencies with and without coagulant aids. Calgon's 2660, 2870, and
Dow's C-32 with montmorillonite clay were judged most effective of all
cationic coagulants evaluated. The Milk River Project (6) reported that
concentrations of Dow's C-31 and C-32 in the range of 3 - 5 mg/1 were
detrimental and/or fatal to fish. Consequently, any overdose of C-31 or
C-32 resulting in supernatant concentrations of cationic polyelectro-
lytes could not be released to a receiving watercourse without further
evaluation. Calgon's 2660 and 2870 and other cationic polyelectrolytes
have not been evaluated in terms of toxicity. It is, therefore, impor-
tant to carefully assess and evaluate environmental impacts of these
cationic polyelectrolytes.
Coagulant aids, Calgon Aid 18 and montmorillonite clay, were judged use-
ful in increasing the removal characteristics of the individual coagu-
lants. Both increase the particle or nucleus concentration in the waste
and perhaps absorb some of the organics. The specific values attached
to the usage of varying coagulant aids should be assessed for individual
applications.
Based on removal efficiency and the above-mentioned important considera-
tions, alum, with or without clay-type coagulant aids, is judged the
most effective coagulant for treatment of urban land runoff in Durham,
North Carolina. Within the choices of treatment alternatives, plain
sedimentation is a reasonable, relatively inexpensive alternate to
chemical treatment of urban land runoff.
Batch Scale Coagulant Evaluation
After final evaluation of the jar tests on each coagulant, batch scale
coagulation, flocculation, and sedimentation tests were run. The
78
-------
purpose was to observe scale up effects, if any, and to determine set-
tling rates and sludge characteristics.
A schematic of the 15-gallon batch process is shown in Figure 50.
Approximately 17 gallons of raw waste was placed in the rapid-mix tank.
The pH was adjusted and the correct amount of coagulant added. The mix-
ture was then agitated at approximately 6000 RPM for three minutes and
then transferred by a centrifugal pump to the flocculation and settling
column. The plexiglass column was 10 feet tall with an inner diameter
of 6-1/4 inches. A one-inch aluminum shaft with two-inch-square paddles
at intervals of one foot were placed in the middle of the column for
flocculation. The shaft was rotated at 20 RPM for 12 minutes by a chain
drive located at the top of the shaft. After flocculation the waste was
allowed to settle. Sampling ports, located at one-foot intervals, were
used during the settling process to develop the settling rate-time rela-
tionship. The results obtained were expressed in terms of percent
removal of suspended solids at each sampling port and time interval,.
These removals were plotted against their respective depths and times.
Smooth curves were drawn connecting points of equal removal. The curves
Sedimentation Column (6.25" x 10'
Mounted on a Steel Frame
Coagulant | |
pH Control
Sample
Lding
ik •'
~
h
0
1 r
O
Pump
< n
r
9 —
)
8 —
7 — .
6 —
A
Sample Ports
(IFt. Apart;-3 —
2 —
1 —
«-
— *
0 —
L
D-
D-
D-
D-
O-
D-
D-
O-
D-
ti
\ *
•
to tor (0-100 ftPM)/"^
-a
-0
-a
-o
-a
-a
-a
-a
-a
-a
T
< Agitator Blad
i
^_ Drain
Figure 50. Schematic of batch coagulation-
sedimentation column.
79
-------
represent the limiting or maximum settling path for the indicated per-
cent. In other words, the specified percent solids will have a settling
path equal to that shown and would, therefore, be removed in an ideal
settling tank of the same depth and detention time. The areal overflow
rate for an ideal settling basin could then be found by dividing the
effective depth by the time required for a given iso-removal line to
settle this depth.
Representative iso-removal lines for selected coagulants are presented
in Figures 51 and 52. These were constructed for each batch test to
assess the areal overflow rate in gallons per day per square foot of
surface area associated with varying suspended solids removal rates.
These overflow rates are for ideal quiescent settling and would have to
be adjusted depending on the relative efficiency of a designed sedimen-
tation basin.
Figure 53 gives the relationship of the percent removal of suspended
solids as a function of areal overflow rate for Dow's C-31, Dow's C-32
and Calgon's 2870. The doses utilized were those found to be optimum in
prior jar tests. On each of the four runs a 90 percent suspended solids
removal was attained at overflow rates of up to approximately 4000
GPD/ft2 and in some cases up to 6000 GPD/ft*.
Figure 54 gives the relationship of suspended solids removal as a func-
tion of areal overflow rate for ferric chloride. Removal efficiencies
as a function of areal overflow rate were sporadic varying from 55 to 96
percent at an overflow rate of 6000 GPD/ft^ of surface area.
Figure 55 describes the relationship between suspended solids removal
and areal overflow rate for alum with and without various coagulant
aids. A 92 to 97 percent suspended solids removal was typically
attained at overflow rates of up to 6000 GPD/ft^ of surface area. Run
Nos. 1 and 5 did not produce as good removal efficiencies as the other
runs. The exact reason for this is unknown.
The areal overflow rate utilized in the jar testing was calculated to be
240 GPD/ft^ of surface area which was substantially less than the magni-
tude of areal overflow rates found to produce equivalent suspended
solids removals in the column tests. It is, therefore, apparent that
the 15-minute settling time utilized in the jar test was extremely con-
servative. The suspended solids removals of the 15-gallon batch tests
are approximately the same as achieved in the jar tests, thus indicating
little, if any, scale-up effects on percent removal..
Sludge Characterization
During the final stages of the project it was deemed important to gain
some insight into the characteristics of the sludges produced as a
result of chemical coagulation of urban land runoff. Consequently, dur-
ing the last 5 column tests the sludge was withdrawn from the bottom of
the sedimentation column. The unit weight, percent solids, and specific
resistance of the sludge was determined. The specific resistance was
determined by the Buchner funnel apparatus as described by Eckenfelder
(3).
80
-------
0
1
2
3
£ 4
A
•g
a5
6
7!
8
45 mg/1 Alum +
8 mg/1 Calgon 7.870
pH • 8
I Removal
10 15
Time, Min.
ZO
82 mg/1 Alum
pH - 8
Time. Mln.
95 J Z Removal
Figure 51. Suspended solids removal as a function
of detention time.
81
-------
10
16 mg/1 Dow C-32
97 ) Z Removal
I
10
I
15
Time Mln.
40 mg/1 FeCl3
pH - 11.
I
20
Removal
Figure 52. Suspended solids removal as a function
of detention time.
82
-------
"8
•o
e
100
90
80
70
00
CO
&
H 60
50 —
Organic Coagulants
1-20 mg/1 C-32
-------
00
100-
90 -
80 —
70 '
60'
50 —
40'
i r i T i i i
78 9 10 11 12 13
Overflow Rate (GPD/ft2 x 10-3)
I
15
1 -
2 -
3 -
4 -
5 -
6 -
Ferric Chloride
20 mg/lit at PH 11.0
20 mg/llt at PH 11.0
50 mg/llt at PH 12.0
40 mg/lit at PH 11.0
35 mg/lit + 1 pig/lit CAL 2870
35 mg/lit -t- 8 mg/lit C-32
16
I
17
18
Figure 54. Suspended solids removal vs. areal overflow rate for ferric chloride.
-------
oo
Ui
100-
90-
80-
70-
60
50 •
40-
Mum
2 -
3 -
5 -
6 -
7 -
75 mg/lit at FH 8.0
82 mg/llt at FH 8.0
60 nig/lit at PH 8.0
70 mg/lit + 2 mg/lit CAL 2870
45 ing/lit + 14 mg/llt CAL 18
45 mg/lit + 8 mg/llt CAL 2870
45 mg/lit + 1 mg/lit 2870
I ! I I I i I I I I I I I I I I I I
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Overflow Rate (GFD/tt2 x 10~3)
Figure 55. Suspended solids removal vs. areal overflow rate for alum with and
without coagulant aids.
-------
The procedure followed was:
1. Whatman No. 2 paper was moistened with water to ensure a
completed seal.
2. 200 ml sludge samples were mixed and transferred to the
Buchner funnel apparatus, and a vacuum was applied.
3. The milliliters of filtrate collected after select time
intervals were recorded. This process was continued until
the vacuum broke.
4. The initial and final solids concentrations were determined
in the raw feed sludge and the cake.
5. The specific resistance of the sludge was then calculated
in accordance with Eckenfelder.
Each of the six determinations of the unit weight, percent solids, and
specific resistance is presented in Table 18. The unit weight of all
sludges was approximately 1.0 as expected with percent solids concentra-
tion varying from 1.3 to 6 percent. The specific resistance varied from
3.0 to 25.6 x 108 sec^/gm at a vacuum of 700 mm. The results of these
six runs should be considered as only indicative of the type of sludge
obtained from chemical treatment of urban land runoff.
Table 18. CHAEACTERISTICS OF CHEMICAL SLUDGES
Coagulant
45 mg/1 Alum + 8 mg/1 2870
45 mg/1 Alum + 4 mg/1 C-32
35 mg/1 FeCl3 + 1 mg/1 2870
35 mg/1 FeCl3 + 8 mg/1 C-32
40 mg/1 FeCl3
60 mg/1 Alum
Sludge Characteristics
Unit wt.
gm/ml
.97
.98
.99
.98
.96
1.02
Percent
solids
1.3
1.2
3.0
3.1
1.8
6.0
Specific
resistance
108 sec2/gm
3.0
7.0
7.4
8.9
25.6
14.0
Summary
The objective of this part of the project was to investigate and evalu-
ate the applicability and effectiveness of chemical coagulation and
plain sedimentation of urban land runoff. Inorganic and organic coagu-
lants were screened initially by jar test evaluation. The selection of
coagulants for additional jar testing were made on the basis of COD,
suspended solids, and turbidity removals as indicated by the residual
removal efficiency over plain sedimentation.
Plain sedimentation for 15 minutes under ideal quiescent conditions was
found to remove an average of 61 percent of the COD, 77 percent of the
86
-------
suspended solids, and 53 percent of the turbidity. Alum, with or with-
out coagulant aids, was judged to be the most effective coagulant for
chemical treatment of urban land runoff based on removal efficiencies
and optimum conditions. An average of 57 mg/1 of alum was found to
effect removals of COD, suspended solids, and turbidity of 84, 97, and
94 percent, respectively.
Batch scale chemical treatment studies indicated little, if any, scale-
up difficulties for chemical treatment. Areal overflow rates of up to
6000 gallons per day per square foot of surface area under ideal condi-
tions produced 92 to 97 percent removal of suspended solids.
Plain sedimentation, being much less costly than chemical coagulation,
removed a significant portion of organics and solids and should be
considered as the first alternative in treatment of urban land runoff.
Chemical coagulation with alum produces significant increases in pollu-
tant removal over plain sedimentation and should be considered an
effective tool for preventing adverse effects of urban land runoff on
water quality management.
87
-------
SECTION VIII
RELATIVE IMPACT OF URBAN LAND RUNOFF
Introduction
The relative impact of urban land runoff on water quality is dependent
on the physical, chemical, and biological characteristics associated
with the particular aqueous system receiving the waste. As each receiv-
ing watercourse tends to differ, the impact—relative or absolute—is
different. Consequently, each municipality must assess the magnitude
of urban runoff for its particular situation. In this project the pol-
lution originating as non-point urban runoff was evaluated in two ways in
an attempt to provide insight into its relative impact on a receiving
watercourse. First, the annual pollutant yield of urban runoff was
evaluated in comparison to municipal waste in terms of pounds and con-
centrations. Second, the influence of urban land runoff on dissolved
oxygen concentrations in a hypothetical situation was evaluated with
respect to point sources.
Comparison with Domestic Waste
The 1.67 square-mile study area is served by the Durham Third Fork acti-
vated sludge sewage treatment plant which receives wastes from a total
area of 9.6 square miles. The average daily waste volume during 1972
was 3.3 MGD with average raw waste concentrations of 205 mg/1 suspended
solids, 285 mg/1 5-day BOD, 7 mg/1 total phosphorus as "P," 4.4 mg/1
nitrate nitrogen, 0.06 mg/1 chromium, 0.12 mg/1 copper, 0.9 mg/1 zinc,
<0.5 mg/1 lead, and <0.1 mg/1 nickel. The plant's average removal effi-
ciency for BOD5 and suspended solids was 91 and 85 percent, respectively.
As a result of the long-term COD uptake rates described previously, it
was determined that approximately 50 percent of the total initial COD of
urban runoff could be biologically degraded in twenty days. Because of
the difficulties experienced with running BOD tests on urban runoff, the
ultimate BOD of urban runoff is assumed to be equal to the percent of
the COD susceptible to biodegradation. As no COD tests were run at the
Durham sewage treatment plant, it is assumed that the 5-day BOD is 68
percent of the ultimate and that the COD of the raw municipal waste is
150 percent of the ultimate BOD. Therefore, the COD of the raw munici-
pal waste is 2.2 (i.e., 1.5 4- 0.68) times the 5-day BOD as measured.
Table 19 compares total quantities of raw municipal wastes and urban
runoff, including base flow, in pounds per acre per year of drainage
basin size. The contribution of urban runoff reflects the adjusted
contribution as described previously in Table 14. Urban runoff contains
the majority of the heavy metals varying from 57 percent of the total
zinc yield to 94 percent of the chromium. It is important to note that
if Durham provided 100 percent removal of organics and suspended solids
from the raw municipal waste on an annual basis, the total reduction of
pollutants discharged to Third Fork Creek would only be 52 percent of
the COD, 59 percent of the ultimate BOD, and only 5 percent of the total
suspended solids.
88
-------
Table 19. COMPARISON OF RAW MUNICIPAL WASTE AND URBAN RUNOFF ON AN
ANNUAL BASIS IN POUNDS PER ACRE PER YEAR POLLUTANT YIELD
Pollutant
COD
BOD Ultimate
Suspended Solids
Kjeldahl Nitrogen as "N"
Nitrate "N"
Total Phosphorus as "P"
Chromium
Copper
Lead
Nickel
Zinc
Raw
municipal
waste
Ibs
1027
685
335
7.2
11
.10
.20
<.8
<.16
1.5
%**
52
59
5
73
6
11
21
12
43
Urban Runoff*
+
base flow
Ibs
938
470
6690
6.1
4.7
1.6
1.6
2.9
1.2
2.0
%**
48
41
95
27
94
89
79
88
57
Total
annual
yield
1965
1155
7025
15.7
1.7
1.8
3.7
1.3
3.5
* See Table 13.
** % of total annual yield.
Table 20 gives the total annual yield of pollutants from municipal and
urban runoff sources in pounds per acre during 1972 based on actual
removal rates for the Durham Third Fork Sewage Treatment Plant. On a
yearly basis the average ultimate BOD reduction is 46 percent, COD—48
percent, and suspended solids—4 percent.
Table 20. TOTAL ANNUAL YIELD OF POLLUTANTS FROM MUNICIPAL AND
URBAN RUNOFF WASTES IN POUNDS/ACRE DURING 1972
Parameter
COD
Ultimate BOD
Suspended Solids
Municipal waste
Raw
1027
685
335
Percent
removal
91*
91
85
Effluent
92
61
50
Urban
runoff
938
470
6690
Total
release
1030
531
6740
Overall
removal
efficiency
48%
46%
4%
*Assumed
Table 21 evaluates the total yield of pollutants from the Third Fork
Creek watershed during those times of urban runoff, which occurred 19
percent of the time or 1680 hours during the year. The urban runoff
contribution used to construct this table does not include pollutant
yield during the 7080 hours of base flow. During the 1680 hours of wet
weather the raw municipal wastes represent only 18 percent of the total
yield of COD, 23 percent of the ultimate BOD, and only 1 percent of the
total suspended solids load. Consequently, if Durham provided 100
89
-------
percent treatment of municipal wastes during these periods, it would
represent an overall reduction of only 18, 23, and 1 percent of COD,
ultimate BOD, and suspended solids to the receiving watercourse.
Table 21. TOTAL YIELD OF POLLUTANTS DURING STORM PERIODS FROM URBAN
RUNOFF AND RAW MUNICIPAL WASTES IN LBS/ACRE DURING 1972
Parameter
COD
Ultimate BOD
Suspended Solids
Raw
municipal
wastes
195
130
64
Urban
runoff
895
447
6617
Total
1090
577
6681
Percent
Municipal^
18
23
1
Runoff
82
77
99
It is important to note that approximately 20 percent of the time down-
stream water quality is not controlled by municipal wastes but by urban
runoff. Even if all raw sewage were completely removed during storm
events, the relative influence on downstream quality would be minimal
compared to the impact of urban land runoff.
Relative Impact on Downstream Oxygen Content
The dissolved oxygen content of water in the drainage system is an
important indicator of the life-sustaining capability of the stream.
In investigating the impact of urban stormwater on downstream oxygen
content, there are many variables which have significant effects. To
apply the results of the present research to this question, it was
necessary to hypothesize an artificial downstream reach in order to
reduce the number of variables to a manageable and meaningful level.
Study Area Characteristics
The watershed selected for study is shown in Figure 56. It is larger
than and includes the watershed from which the source data for this
research were taken. The study watershed has a drainage area of 9.6
square miles. The effluent of the Third Fork Creek Waste Treatment
Plant of the City of Durham is discharged into the stream at the outlet
of the study basin. The study watershed is urbanized to the same
degree as the watershed monitored.
The reach of interest was the segment of Third Fork Creek below the
municipal waste treatment plant.
Problem Formulation
The question was investigated by applying the Streeter-Phelps oxygen-
sag equations to the mixed streams issuing from the study watershed and
from the municipal waste treatment plant. The coordinates of the sag
point were determined as follows:
90
-------
STUDY AREA
N
TREATMENT
PLANT
USGS
GAGING
STATION
BASIN BOUNDARY
"7
Third Fork Creek
Drainage Area at Treatment Plant
= 9.6 sq. mi.
Figure 56. Watershed selected for oxygen sag studies.
The time to the sag point is given by:
where t = flow time to the sag point (days)
k =
f =
k_ =
Da =
deoxygenation rate constant of the waste, base-e form
(per day)
k2/k1
reoxygenation rate constant of the stream, base-e form
(per day)
initial dissolved oxygen deficit, relative to saturation
Cmg/1)
La = initial ultimate BOD (mg/1)
91
-------
The maximum D.O. deficit, DC in mg/1, is given by
-k.t
, 1 c
La e
Dc = _
The reach of interest receives flow from several minor streams before
it empties into the larger New Hope Creek about ten miles below the
municipal treatment plant. The simulation of the real stream system
would involve a complex set of variables describing the influence of the
flow characteristics and oxygen demands of the various tributaries
which join the study reach. The uncertainties inherent in such a simu-
lation obscure the basic issue of the impact of stormwater runoff in
the downstream areas. Accordingly, the stream characteristics just
below the municipal treatment plant were assumed to be continuous for
an indefinite distance downstream. The effect of this assumption was to
consider the reach of interest to be neither improved nor degraded by
other tributaries or pollution sources. Thus, the impact question was
made less specific to the local situation.
A one-inch rainfall occurring over 5 hours was selected for study pur-
poses. A linear hydrograph approximating the flow response of the
stream to this storm at the watershed outlet is shown in Figure 57.
Instantaneous estimates of ultimate BOD loading in the storm wave are
also shown in Figure 57- These were based on the COD regression equa-
tion given in Table 11; i.e.,
1 11 —0 9ft
COD = 0.51 CFS TFSS
where CFS = streamflow (cfs)
TFSS = time from beginning of storm (hr)
COD = chemical oxygen demand (Ib/min)
This equation estimates COD near the stream bottom. Average COD for the
stream appears to be 84 percent of this value. Further, 44 percent of
the COD is estimated to be biodegradable. Using these figures, together
with the appropriate unit conversion factor, the estimating equation for
ultimate BOD is
1 I-] _n OQ
BOD =11.2 CFS TFSS
u
where BOD is expressed in Ib/hr.
The value of the reaeration coefficient, ^2, is strongly influenced by
the shape of the channel cross-section and the magnitude of flow. For
the purpose of estimating the value of the reaeration coefficient, the
formulation of O'Connor and Dobbins (4) was used. Restated in the
base-e form, their equation under conditions of non-isotropic turbu-
lence is
k = 1100 DP-V-25^1-25
92
-------
500,-
Typlcal Storm
Hydrograph
Rain - 1.09 In. over 5 hrs.
14 16 18
Time, (hrs.)
30
Figure 57. Typical storm for conditions at Third Fork Creek
treatment plant .
where k_ = reaeration coefficient, base-e form (per day)
L 2
D = coefficient of molecular diffusion (ft /day)
lj
S = channel slope (ft/ft)
H = hydraulic depth (ft)
2
The value of DL was taken at 0.002 ft /day, based on stream character-
istics, in which case the equation reduces to
k2 - 50 S°'25 H-1'25.
Several channel shapes were investigated as to their effect on the
reaeration coefficient. A rectangular channel was selected because
actual Third Fork Creek stream banks are typically steep. The variation
of k£ with flow is shown in Figure 58 for rectangular and trapezoidal
channels having the same gross cross-sectional area. Flows and
93
-------
10
n - 0.1
8 - 0.00135 /ft
20
30 40 50
60 70 80 90 100
Flow (cfs)
200 300 400 500 700 900
600 800 1000
Figure 58. Effect of channel shape and flow variation on
reaeration coefficient.
corresponding hydraulic depths were computed with the Manning equation
using a slope of 1.35 feet per thousand feet and a roughness coefficient
of 0.1, as estimated for the real stream.
In order to determine the effect of channel storage on the shape of the
hydrograph, the storm wave was routed through approximately 20 miles of
the stream by conventional routing methods assuming constant channel
characteristics and no intervening contributory flow. The results of
the routing are shown in Figure 59. The intermediate hydrograph
(approximately 10 miles downstream) was used to estimate typical flow
values for various components of the illustrative storm.
The illustrative storm was divided into four components for study. Each
component was assumed to be completely mixed with no intermixing between
component parts. The components were the first flush, the peak, .the
falling limb and the tail. The arbitrarily selected component boundar-
ies are shown in Figure 57 - In each case the initial ultimate BOD for
the component was computed from the ratio of total pounds of BOD to
total volume of water.
94
-------
500
400
, 300
1*4
u
•»• 200
o
(H
* 100
0
400
« 300
Peak 460 cfs
Rectangular Channel
luT1
30'
30 32 34 36 38 40 42 44 46 48 50 52 54 56
- 200
100
°l
400
300
200
100
0
Basin Outlet
Elapsed lime from Start of Storm, Hours
Peak 315 cfs
2468
50 52 54 56
50,000 ft (9.5ml) downstream
Elapsed Time from Start of Storm, Hours
100,000 ft (19 ml) downstream
I—T—\—I—I—I—I—I—I—I—FT
2 46 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56
Elapsed Time from Start of Storm, Hours
Figure 59. Effect of channel storage on storm flow downstream.
-------
In addition to the illustrative storm described previously, a larger
storm having a return period of approximately 5 years and two very
small storms were modeled in a similar manner to examine the effect of
storm size.
The municipal treatment plant was assumed to be at average flow, BOD
and DO conditions in each case treated.
For each entry into the sag equations, four parameters from the upstream
reach and the plant effluent were required. These were the flow, tem-
perature, ultimate BOD and dissolved oxygen concent. Table 22 lists the
input data together with the results of the sag computations.
The sag computations were repeated for several levels of BOD removal
from the stormwater stream. These results are given in the same table.
Interpretation of Results
The oxygen-sag studies show that the question of impact of urban storm-
water runoff on the oxygen content of downstream reaches is very com-
plex. Many factors are involved, and there are large variations from
place to place and from storm to storm. It does appear, however, that
some generalizations are appropriate.
The reaeration coefficient in the downstream reach is highly variable,
being a function of the channel characteristics and the rate of flow.
The previously cited O'Connor and Dobbins formulation shows that the
rate of reaeration is inversely related to the flow rate, provided there
is significant flow. At very low flows, water tends to collect in chan-
nel depressions and irregularities such that velocity is essentially
zero over much of the channel length. The commonly accepted reaeration
coefficients for these conditions are very low—of the order of 0.10 to
0.15 per day (base e).
The studies confirm the existence of a first-flush effect, evidencing
higher pollutant concentrations in the early storm stages which
decrease as the storm progresses. The interactions of changing BOD con-
centrations and changing reaeration rates produce the greatest dis-
solved oxygen deficit in the slug of water which includes peak flow.
As storm size increases, the depletory effect on downstream dissolved
oxygen is more pronounced. At comparative time intervals larger storms
have higher BOD concentrations and lower reaeration rates. Small storms
are depicted by the model discussed here as causing no deficit whatever
in dissolved oxygen. The interpretation of these results, however, must
be tempered by the fact that the value of the reaeration rate constant
is difficult to predict at low flows because of the effect of channel
irregularities. Also, examination of COD concentration of small storms
in the source data leads one to suspect that the regression equation
obtained from the full data set may underestimate the pollutant yield
of small storms. Accordingly, it is recommended that special attention
be given to small storms under actual conditions prevailing in any real
basin under consideration.
96
-------
Table 22. RESULTS OF OXYGEN-SAG COMPUTATIONS FOR STUDY WATERSHED
Storm Type
Small Storm
Small Storm
1-2 year Storm
5-year Storm
7-day, 10-year Low
f 1 nu
Rain-
fall
(in)
0.1
0.1
1.0
3.3
-
Dura-
tion
(hr)
1
3
5
5
-
Return
Period
(yr)
.
_
1 to 2
5
-
Storm
Component
Total
Storm
Total
Storm
First
Flush
Peak
Falling
Limb
Tail
First
Flush
Peak
Falling
Limb
Tail
-
Storm
Flow
(cfs)
40
20
200
315
200
75
500
1100
800
300
0.3
Reaeration
Coefficient
(per day)
4.00
5.70
1.25
0.86
1.25
2.75
0.58
0.32
0.40
0.90
0.13
Ultimate
BOD
(mg/1)
40
31
75
62
47
37
85
70
54
42
15
Deoxygena-
tion
Coefficient
(per day)
0.12
0.12
0.12
0.12
0.12
0.12
0.12
0.12
0.12
0.12
0.12
Flow
Time
to Sag
Point
(day)
0
0
2.0
2.6
1.9
0.8
3.4
4.8
4.2
2.4
6.0
D.O.
Deficit
at Sag
Point
(mg/1)
0
0
5.6
6.3
3.5
1.4
11.7
14.7
9.7
4.1
11.9
D.O.
at
Sag
Point
(mg/1)
10.0
10.0
4.5
3.8
6.5
8.7
0*
0*
0.3
5.9
0*
D.O. (mg/1) at Sag
Point With Stated
BOD Removal from
Stormwater
207.
_
_
5.6
5.0
7.2
8.9
0.7
0*
2.3
6.8
0*
407.
_
_
6.7
6.3
7.9
9.1
3.0
1.2
4.2
7.6
0*
60Z
_
_
7.8
7.5
8.6
10.0
5.3
4.1
6.1
8.4
0*
* Anaerobic
Notes:
1. Treatment Plant Parameters for all Cases: Flow - 5.1 cfs
BOD - 27 mg/1
D.O. -3.3 mg/1
2. Water temperature assumed to be 60°F.
3. Initial stormwater D.O. estimated at 9.5 mg/1 based on watershed observations.
-------
One of the principal research objectives was to ascertain the relative
effects of upgrading the municipal treatment plant and of treating
urban stormwater. The results from the hypothetical situation indi-
cate that under storm flow conditions, downstream oxygen content is
relatively independent of the degree of. treatment at the municipal
treatment plant. Oxygen-sag estimates are unchanged if the secondary
treatment level in the municipal plant is upgraded to 100 percent BOD
removal in the plant effluent. On the other hand, at extreme low-flow
levels the downstream water quality remains unaffected by water quality
upstream from the plant. Therefore, if a desired dissolved oxygen con-
tent is to be maintained downstream from the plant under storm condi-
tions, treatment of the stormwater is necessary.
Under these study conditions and subject to the limitations of the
assumptions, simplifications and local applicability, the effects of
various levels of BOD removal from the urban land runoff were investi-
gated with respect to improving the sag-point oxygen content. The
results are summarized in Figure 60. This figure is not intended for
design purposes, but it does indicate the degree to which treatment of
stormwater might affect improvement in downstream water quality.
Total Storm - Small Storm
c
8
g
u
Typical Storm
Five-year Storm
20
40
00
8(5
X Removal of BOD
Figure 60. Effect of stormwater treatment on oxygen
sag under storm conditions.
98
-------
Elsewhere in this report the COD removal efficiency of plain sedimenta-
tion under quiescent settling conditions is shown to average 60 percent.
Thus, significant benefits may be obtained from installation of holding
ponds designed for organic removal by sedimentation. Such a facility
could be usefully designed for other objectives such as reduction of
flooding and entrapment of urban sediment.
The study of downstream effects described above assumed constant channel
characteristics for an indefinite stream length below the discharge
point. Because of the importance of the value of the reaeration rate
constant, critical conditions would be suspected where urban streams
discharge into nearby static bodies of water. Such conditions might be
expected where large urban areas are near estuaries, such as Richmond,
Virginia, or Washington, D. C., or where urban streams discharge into
reservoirs.
If it is accepted that the 7-day, 10-year low flow is an appropriate
design criterion for dry conditions in the stream, contravention of
minimum standards would be expected on an average of once in 10 years.
These hypothetical studies of the impact of urban land runoff on water
quality indicate that the 5-year storm may impose more severe depletions
of dissolved oxygen than the accepted dry-flow criterion. Therefore, to
be consistent in overall water quality management, it appears necessary
to develop concepts and criteria applying to urban stormwater runoff.
While the degree of oxygen depletion may be more severe in a large storm
event than in a protracted dry period, it is also of shorter duration.
Summary
The purpose of this section was impact assessment of urban runoff on
water quality.
Urban runoff in the basin monitored was compared in quality and quantity
to municipal waste. Municipal waste was found to have higher organic
content while urban runoff contains much higher levels of suspended
solids and metals. From the data collected, it may be inferred that if
the City of Durham were to remove 100 percent of organics and suspended
solids, the net reduction in total raw waste components would be 52 per-
cent of the COD, 59 percent of the ultimate BOD and only 5 percent df
the total suspended solids on an average annual basis. The delivery of
urban runoff contaminants, however, is highly specific to wet-weather
flow. During wet periods, approximately 20 percent of the time in this
study, stormwater contributes 82 percent of the COD, 77 percent of the
BOD, and 99 percent of the suspended solids in the potential raw waste
load of the watershed.
The influence of urban stormwater on downstream dissolved oxygen content
was investigated by applying oxygen-sag concepts to a hypothetical chan-
nel draining an urban watershed. At the outlet of the watershed the
effluent of a secondary municipal treatment plant, which serves the same
watershed, is discharged. Selected storms were routed through the chan-
nel using the COD regression equation developed earlier as a basis for
estimating oxygen demand in the stream due to stormwater contaminants.
99
-------
Storms were divided into four parts: the first flush, peak, falling
limb, and tail. Within storms the study shows that the slug of water
which includes the peak sustains the most severe downstream oxygen
depletion. For comparable parts of storms, the depletory effect
increases with increasing storm size. The value of the reaeration con-
stant for the stream reach under consideration varies considerably with
depth of flow, having a profound effect on the degree of oxygen deple-
tion. During storm events, the effect of the treatment plant effluent
is not detectable in oxygen-sag computations. Therefore, if improvement
in minimum downstream dissolved oxygen content during wet weather is
required, treatment of stormwater is necessary.
100
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SECTION IX
FACTORS INFLUENCING STORMWATER TREATMENT ECONOMICS
Introduction
This research was primarily concerned with the characterization of urban
stormwater as to quality and with investigation of alternative means of
treatment. The following discussion of treatment economics necessarily
touches on areas outside the project scope but which have an important
bearing on final treatment cost. Consequently, these economic con-
siderations are mainly subjective and not quantitative, consisting of
suggestions of alternatives to be investigated by others as they may
apply in particular circumstances.
Treatment costs may be divided into cost categories of collection,
treatment, and final sludge disposal.
Collection
The nature of the existing storm-drainage system will dictate to a great
extent what type of facility is best for urban stormwater treatment. In
conventional domestic waste collection/treatment systems, the collection
system comprises 70 to 80 percent of the cost. Where existing storm
drainage is combined with the sanitary system, separation is economi-
cally inefficient by inspection if stormwater is to be treated. The
accommodation of storm surges by flow equalization through storage
appears to be a better choice.
The question of treatment economics is perhaps more unconstrained where
separate systems exist or where none exists as in the case of a new
town. Typically, in separate systems, stormwater is conveyed to the
nearest natural drainage channel. In such a system, alternatives for
stormwater treatment range from interception and centralized treatment
to dispersed treatment along natural watercourses. Throughout this
range, economics of plant size and plant density are evident.
An influence on the plant location decision is the degree to which water
quality is to be assured in small streams. If, for instance, dissolved-
oxygen content is to be supported in small collector streams, a larger
number of small plants may be required. Alternatively, some of these
streams might be enclosed in pipes to reduce the number of plants. If
water quality requirements are to be in force only on those streams
leaving urban areas, fewer and larger plants are indicated.
Some non-structural alternatives to plant treatment in small watersheds
are feasible. In street-cleaning operations, vacuum sweeping might
replace street flushing to reduce the quantity of contaminants delivered
to the stream. Drainage design policies might be changed to exploit the
storage and natural percolation capacities of the watershed. This could
be accomplished by minimizing piped flow in areas such as parks, and by
causing drainage to occur in sheet flow through vegetated strips.
101
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It is evident that the outcome of considerations mentioned above will
constrain plant size and type. Conversely, the plant cost function,
practical size limitations, and land availability will determine to
some degree the needs of the stormwater collection system.
Treatment
Given that the drainage area and stormwater quality characteristics are
set, a range of alternatives exist for treatment, depending on required
effluent quality.
It has been demonstrated earlier that plain sedimentation will remove
approximately 60 percent of the COD under quiescent conditions. This
fact, coupled with the observation that reduction in downstream flow
rate could be expected to increase the reaeration rate, suggests that
simple storage of the entire or early fraction of the storm wave might
significantly improve water quality under certain circumstances. Pre-
liminary estimates indicate that a holding pond of 20 acre feet per
square mile of drainage basin would reduce the peak outflow of a 5-year
storm td one-half the peak inflow. The downstream reaeration rate
would be about 70 percent higher as a result of the flow reduction,
depending on channel characteristics. The settling efficiency of such
a storage pond is estimated to vary from about 30 percent removal of
COD, at peak flow of the 5-year storm, to approach 60 percent removal
at lower flows. Whether such a facility can satisfactorily improve
urban water quality is dependent on stream standards, hydraulic and
pollutional loading of the facility, and characteristics of the down-
stream reach. If a large number of small facilities are contemplated,
temporary storage and simple sedimentation are feasible. Additional
benefits accrue from the reduction of urban flood peaks and from the
entrapment of urban sediment.
The physical-chemical process of coagulation-sedimentation appears to be
an economical treatment method if plain sedimentation is not sufficient.
A typical installation might consist of a detention pond to hold that
fraction of the storm wave having the highest level of. contamination
and a treatment facility for the operations of chemical feed, flash mix,
flocculation, and sedimentation. It may be readily observed that an
economic trade-off exists between the size of the storage pond and the
flow capacity of the treatment facility, given the nature of the design
storm. Thus, land cost would be expected to be a strong influence on
economic plant size. Elsewhere in this report are discussions and
recommendations regarding specific coagulating agents.
Sludge Disposal
The high turbulence of flowing stormwater supports its high suspended
solids content. So anywhere that stormwater is slowed and detained,
sediment will accumulate. This effect would be exploited in a system
of ponds for simple sedimentation. The sediment to be removed from such
a pond would consist primarily of relatively coarse materials. Removal
could be effected by draining the pond, allowing the deposits to dry and
102
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excavating them by ordinary earth-moving procedures. Material thus
taken may be disposed of as low-quality fill. Since it would be highly
erodible, it should be stabilized. It can be beneficially used as
daily cover in a sanitary landfill.
Where stormwater treatment beyond simple sedimentation is undertaken,
the sludge disposal problem is more severe. The sludge which results
from the flocculation operation is light and fluffy. Dewatering
difficulties would be expected, and ultimate disposal would be subject
to the same considerations as in municipal treatment plants.
Summary
The question of treatment economics was investigated and determined to
be highly sensitive to such local parameters as the nature of quality
standards, the nature of existing stormwater collection and disposal,
and the degree of treatment required. The data collected within the
scope of this project does not permit detailed economic analysis of
alternative treatment decisions. The principal contribution of this
research to the question of treatment economics lies in the quantifi-
cation of pollutional and hydraulic loadings which will serve as part
of the data base for analysis by others in relation to project develop-
ment in specific watersheds.
103
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SECTION X
EVALUATION OF EPA STORM WATER MANAGEMENT MODEL
Introduction
One objective of the project was to evaluate the effectiveness of EPA's
Storm Water Management Model (SWMM) (7) in predicting the quality and
quantity of runoff from the Third Fork Creek drainage basin. Four storm
events were modeled for comparison with the main gaging site observa-
tions and two at sub-basin N-2. The model is designed to simulate
urban stormwater runoff phenomena with quality and quantity being the
descriptors. The model's primary objective is to give engineers a tool
with which to assess, evaluate, and control problems associated with
excess urban surface waters.
The SWMM Model
The Storm Water Management Model uses a high-speed digital computer to
simulate real storm events on the basis of rainfall (hyetograph) inputs
and system (catchment, conveyance, storage/treatment, and receiving
water) characterization to predict outcomes in the form of quantity and
quality of runoff. The simulation technique—that is, the representa-
tion of the physical systems identifiable within the model—was selected
since it permits relatively easy interpretation, location of remedial
devices (such as a storage tank or relief lines), and/or denotes local-
ized problems (such as flooding) at a great number of points within the
physical system. The SWMM program objectives are particularly directed
toward complete time and spatial effects, as opposed to simple maxima
(i.e., rational formula approach) or only gross effects (i.e., total
gross pounds of pollutant).
In simplest terms the program is built up as follows:
1. The input sources:
RUNOFF generates surface runoff based on an arbitrary rainfall
hyetograph, antecedent conditions, land use, and topography.
FILTH generates dry weather sanitary flow based on land use,
population density, and other factors.
1NFIL generates infiltration into the sewer system based on
available groundwater and sewer condition.
2. The central core:
TRANS carries and combines the inputs through the sewer system
in accordance with Manning's equations and continuity; it
assumes complete mixing at various inlet points.
3. The correctional devices:
TSTRDT. TSTCST, STORAG, TREAT, and TRCOST modify hydrographs
and pollutographs at selected points in the sewer system,
104
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accounting for retention time, treatment efficiency, and other
parameters; associated costs are computed also.
4. The effect (receiving waters):
RECEIV routes hydrographs and pollutographs through the
receiving waters, which may consist of a stream, stream bed,
lake or estuary.
The quality constituents simulated by the model are the 5-day BOD, total
suspended solids, total coliforms (represented as a conservative pollu-
tant), and dissolved oxygen.
Program Blocks
The adopted programming arrangement consists of a main control and
service block, the Executive Block, and four computational blocks: (1)
Runoff Block, (2) Transport Block, (3) Storage Block, and (4) Receiving
Water Block.
The Executive Block assigns logical units (disk/tape/drum), determines
the block or sequence of blocks to be executed, and, on call, produces
graphs of selected results on a line printer. Thus, this Block does no
computation as such while each of the other four blocks are set up to
carry through a major step in the quantity and quality computations.
All access to the computational blocks and transfers between them must
pass through sub-routine MAIN of the Executive Block. Transfers are
accomplished on off-line devices (disk/tape/drum) which may be saved for
multiple trials or permanent record.
The Runoff Block computes the stormwater runoff and its characteristics
for a given storm for each sub-catchment and stores the results in the
form of hydrographs and pollutographs at inlets to the main sewer system.
The Transport Block sets up pre-storm conditions by computing dry wea-
ther flow and infiltration. The block then performs its primary func-
tion of flow and quality routing by picking up runoff at various input
locations and producing combined flow hydrographs and pollutographs at
intermediate points and for the total drainage basin.
The Storage Block uses the output of the Transport Block and modifies
the flow and characteristics at a given point or points according to
the predefined storage and treatment facilities provided. Costs asso-
ciated with the construction and operation of the storage/treatment
facilities are computed.
The Receiving Water Block accepts the output of the Transport Block
directly or the modified output of the Storage Block and computes the
dispersion and effects of the discharge in the receiving river, lake
or bay.
General Data Requirements
A generalized listing of data requirements prior to the use of the pro-
gram are given on the following page:
105
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ITEM 1. Study Area Definition
Land use, topography, population distribution census
tract data, aerial photos, area boundaries.
ITEM 2. System Definition
Acquire plans of the collection system to define branch-
ing, sizes, and slopes. Types and general locations of
inlet structures.
ITEM 3. Define System Specialties
Flow diversions, regulators, storage basins.
ITEM 4. Define System Maintenance
Street sweeping (description and frequency). Catch-
basin cleaning. Trouble spots (flooding).
ITEM 5. Define the Receiving Waters
General description (estuary, river, or lake). Mea-
sured data (flow, tides, topography, water quality).
Application to Third Fork Creek Drainage Basin
Data for the purpose of modeling the drainage basin was obtained princi-
pally from the Durham Department of Public Works. Topographical, land
use, and storm sewer maps contained the bulk of the data, supplemented
with street cleaning data. Aerial photos were obtained from the North
Carolina State Highway Commission. Also, several days of on-site
investigation were necessary to determine cross-sectional area of man-
made and natural conduits, catchbasin density, and data verification.
With data collection complete and with the intent to make each sub-
catchment representative of a dominate land use, discretization was
accomplished. However, the intention was not fully realized, as many of
the 38 subcatchments had to be defined on the basis of drainage area
instead of land use. Integrated land uses and the natural drainage
channel network made any other division unrealistic. Figure 61 indi-
cates the subcatchment boundary arrangement with respective numbers.
The subcatchments were then subdivided into 119 subareas by totaling
the acreage within the subcatchments for each of the five available land
uses within SWMM. Subcatchment and subarea data were collected as
prescribed by Volume III - The User's Manual (7).
The Third Fork Creek Basin stormwater drainage system is a combination
of gutters and pipes which empty into natural drainage channels. The
modeled drainage system is shown in Figure 61. Gutters and pipes in
the Runoff Block are not numbered due to a lack of space. Fifty gutters
and/or pipes were modeled for the Runoff Block while 146 manholes and
conduits were modeled for the Transport Block. Manholes were placed in
the system whenever conduit cross-sectional area changed, a change in
slope occurred, and/or at conduit junctions. Element No. 19 represents
106
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D - Inlet Manhole
O Manhole
Basin
Outfall
Figure 61. SWMM map of Third Fork Creek system.
the outfall for the North-2 sub-basin with Element No. 100 being the
entire basin's outfall.
Only in those places where piping became necessary (e.g., under streets,
Central Business District, etc.) were conduits well defined hydrauli-
cally. Man-made conduit shapes presented no problems; however, natural
channels with constantly changing cross-sections presented a definite
problem in specifying an equivalent man-made shape. Natural channels
were approximated as semi-circular. Difficulties were experienced in
characterizing roughness coefficients in natural channels. Roughness
coefficients ranged from 0.03 to 0.09 for natural channels.
107
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SWMM Verification
The first storm modeled was that of June 20, 1972, with a total rainfall
of 0.24 inches. The predicted quantity of flow is given in Table 23.
Table 23. STORM OF 6/20/72 AS PREDICTED BY SWMM
Ac tual
Predicted
Peak Q
CFS
75
54
Total volume
ft3
263,000
276,000
Time of peak
military time
0810
0720
The predicted total volume of runoff compares favorably (5 percent
error) whereas the predicted peak is 72 percent of the actual and the
time of the predicted peak is approximately one hour ahead of the
actual. After careful consideration it was thought that the apparent
difference in the time of the peak and the magnitude could be caused by
the following six factors:
1. The hyetograph interval (10 minutes initially) could have the
effect of decreasing "runoff peaks;
2. The integration period, if too large, could have a dampening
effect on the peaks;
3. If the drainage channel slopes were in error and too steep,
runoff peaks would occur too soon;
4. Manning's roughness coefficient for the natural channel, if
too small, could theoretically cause peaks to occur
prematurely;
5. If default values assumed for surface infiltration calcula-
tion did not approximate actual values, volumes of total
gutter flow (computed vs. recorded) would be different; and
6. If default values assumed for surface runoff resistance
(0.25) in previous areas were low, computed peak runoff
would tend to occur before the actual occurrence.
A check of Table 23 reveals little difference in the total volume of
computed gutter flow as compared to the recorded value. Therefore, the
assumed default values for surface infiltration were considered correct.
A recheck of drainage channel slopes indicated no changes had to be
made. Factors 1, 2, 4, and 6 were tested to see what effect an error or
change in data would have.
First, a series of four modeling runs were made to see what effect
changes of hyetograph intervals and integration periods would have on
the June 20, 1972, storm. The following cases were tested:
Integration Period, min.
Hyetograph Interval, min.
Case 1
10
10
Case 2
5
5
Case 3
5
2.5
Case 4
3
2.5
108
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Each case was analyzed by hydrograph comparisons,
analysis are given in Table 24.
Results of the
Table 24. EFFECT OF VARYING INTEGRATION PERIOD AND HYETOGRAPH
INTERVAL ON DISCHARGES AS PREDICTED IN SWMM
ON THE STORM OF 6/20/72
Case 1
Case 2
Case 3
Case 4
Computed vs. recorded percent error
Peak discharge
- 28%
- 11%
- 27%
- 17%
Total discharge
+ 5%
+ 23%
0%
- 5%
Computed vs. recorded
time of peak difference
50 min. lead
45 min. lead
50 min. lead
50 min . lead
None of the above changes produced significantly better comparisons.
Hence, all verification was conducted with a 5.0 minute integration
period and a hyetograph interval of 5.0 minutes.
Secondly, natural channel roughness coefficients were changed. After
reviewing conditions of the natural stream channels, a substantial num-
ber of roughness coefficients were raised to 0.09. The time differen-
tial was not changed at all, and the peak runoff was virtually unchanged
as a result of raising roughness coefficients.
Lastly, the surface resistance factor was modified. Initially, the
default value of 0.25 was used, and the change was to a value of 0.35
for all previous areas. Again, no difference was observed in the com-
puted output.
Verification testing was then resumed using a 5-minute integration
period and hyetograph interval and default values for surface resistance.
A total of four storms were modeled and compared in the verification
tests. Modeled storm dates and characteristics are listed as follows:
Storm date Volume of rainfall, in. Duration, hr.
6-20-72
8-28-72
9-21-72
10- 5-72
0.24
0.06
0.50
2.10
7.50
2.25
9.66
7.50
Two sampling locations were used in verification testing. Storm data
from the main gaging station in the USGS station (inlet No. 100) was
compared for each storm. Sub-basin North-2 data were compared for the
storm events occurring on dates 6-20-72 and 10-5-72. Computed/modeled
outflow hydrographs and pollutographs for the North-2 sub-basin come
from the modeled inlet No. 19 -
Evaluation of Predicted Quantities of Runoff
Figures 62 through 65 give rainfall hyetographs with SWMM predicted
versus recorded hydrographs for the basin outfall. The storm occurring
109
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on 9/21/72 appears to have a good fit timewise. Even then, computed and
recorded peak discharges are significantly different. The comparison of
peak flows, total volume, and time of peak for the main gaging station
are presented in Table 25.
Table 25. COMPARISON OF PREDICTED PEAK FLOWS, TOTAL GUTTER FLOWS,
AND TIME OF PEAKS FOR THE FOUR STORMS MODELED
6-20-72 COMPUTED
RECORDED
8-28-72 COMPUTED
RECORDED
9-21-72 COMPUTED
RECORDED
10-5-72 COMPUTED
RECORDED
Peak runoff
cf s
67
75
6.7
4.3
59
42
425
870
% Error
11
56
40.5
51
Total gutter flow
ft-*
309430
263738
29978
15780
594778
199534
3115659
7572000
% Error
17
89
198
59
Time of peak
24 hr.
clock
0720
0810
1110
1205
0840
0855
1135
1210
Difference
50 min. lead
55 min. lead
15 min. lead
35 min. lead
2
1.0
Computed
Storm No. 26
8/28/72
0.06 In. rain
Recorded
1000 1030 1100
i - \ - 1 - T
1130 1200 1230 1300
Time, hrs.
0.1
0.5
0.10
Figure 62. Modeled vs. recorded hydrograph for USGS main gaging
station with associated hyetograph.
110
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I
Storm No. 20
6/20/72
0.24 in. rain
0.1 .
h
0.2 3
0.3 3
m
s
0.4 o
M
H
0.5 "3
•+4
5
90
75
a
-------
1100
Time, hrs.
Figure 65.
Modeled vs. recorded hydrograph for USGS main
gaging station with associated hyetograph.
Computed and recorded outflow hydrographs for the North-2 sub-basin are
in Figures 66 and 67. A comparison of computed versus recorded hydro-
graphs reveals a rather good fit for both storms. In view of the per-
cent error as listed in Table 26, one might wish to differ with that
statement; however, considering that stage readings were taken manually
20 to 30 minutes apart, there appears to be agreement. Values in
Table 26 pertain only to the time period recorded stage readings that
were taken and not for the duration of the storm.
Table 26. COMPARISON OF PREDICTED PEAK FLOWS, TOTAL GUTTER FLOWS AND
TIME OF PEAKS FOR THE STORMS MODELED AT SUB-BASIN N-2
6-20-72 COMPUTED
RECORDED
10-5-72 COMPUTED
RECORDED
Peak runoff
cfs
24
18.5
107
102
% Error
30
5
Total gutter flow
ft3
40,200
75,780
295,200
416,400
% Error
47
30
Time of peak
24 -hr.
clock
0710
0730
0840
0850
Difference
20 min. lead
10 min. lead
112
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SUB-BASIN N-2
— 0.1
0800
Figure 66,
26
24
22
20
18
16
14
12
10
8
6
4
2
Figure 67,
0900
1000 1100
Time, hrs.
1200
1300
Modeled vs. recorded hydrograph for Sub-basin
North-2 with associated hyetograph.
Storm No. 20
6/20/72
0.24 in. rain
Computed
Recorded
0.1 «
a
0.2 "
0.3 «
0.5
I
0700
0800
1000
0900
Tip*, firs.
Modeled vs. recorded hydrograph for Sub-basin
North-2 with associated hyetograph.
113
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Evaluation of Predicted Quality of Runoff
Although the SWMM is capable of simulating pollutographs for BOD, sus-
pended solids, total coliform, and dissolved oxygen, only suspended
solids was chosen for comparison. Neither total coliform nor dissolved
oxygen were used because the analysis of observed runoff did not include
those two pollutant parameters. BOD was not used for reasons included
in the chapter on characterization.
The storm events of 6/20/72 and 10/5/72 were chosen for comparison of
predicted suspended solids concentration at the USGS station. The storm
of 6/20/72 was also modeled at Sub-basin N-2. The comparison of pre-
dicted versus actual conditions are shown in Figures 68, 69, and 70.
With the possible exception of peak suspended solids time coincidence,
very little agreement was found. Computed and recorded peak suspended
solids for each storm were vastly different. Due to the wide differ-
ences in the computed and recorded values, further comparative analysis
was not attempted.
2620 I—
Third Fork Creek Basin
Storm Date: 6/20/72
0.24 in. rain
1500 —
1000 —
T—I—I—I—I—I
0600 0630 0700 0730 0800 0830 0900 0930 1000 1030 1100
Time, Hours
Figure 68. Modeled vs. recorded suspended solids concentration
for storm of 6/20/72.
114
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1600 r—
N-2 Basin
Storm Date: 6/20/72
0.24 In. rain
200 _
1 I I I I I I I I 1 I
0600 0630 0700 0730 0800 0830 0900 0930 1000 1030 1100
Time, Hours
Figure 69. Modeled vs. recorded suspended solids concentra-
tion for storm of 6/20/72.
Summary
As a result of modeling four actual storm events with the Storm Water
Management Model in Durham, North Carolina, it appears that:
1. The total volume of discharge as predicted by the model
appears to be within an acceptable range of the actual
measurements.
2. The predicted time of peak discharge is approximately 40-50
minutes ahead of that measured for the 1.67 square-mile
drainage basin.
3. The predicted peak discharge is less than that measured in
the field for the total basin.
4. The time and peak discharge is approximated better by the
model for situations involving man-made conduits than it
is for situations involving natural channels.
5. The flux of suspended solids as predicted by the model is
substantially less than that observed in the field.
On the basis of the experience gained with the model in Durham, North
Carolina, it is recommended that:
1. The limit of 160 sewer elements in the transport block be
increased.
115
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3000
2800
2600
2400
2200
2000
1800
•S 1400
S
a.
a
« 1200
1000
800
600
400
200
Storm Date: 10-5-72
2.10 in. rain
Integration Period: 5.0 min.
Hyetograph Interval: 5.0 min.
0800 0830 0900 0930 1000 1030 1100 1130 1200 1230
Time, 24 hr. clock
Figure 70. Modeled vs. recorded suspended solids concen-
tration for storm of 10/5/72 at USGS station.
2. Consideration be given to the inclusion of additional types
of land use classifications such as expressways, construction
sites, and large parking lots.
3. A natural drainage channel shape be included in the list of
man-made conduit shapes.
4. The functions generating suspended solids concentrations
need additional refinement.
116
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SECTION XI
REFERENCES
1. Bryan, E. H., Quality of Stormwater Drainage from Urban-Land Areas
in North Carolina, Report No. 37, Water Resources Research Institute
of The University of North Carolina, Raleigh, N. C., 1970.
2. Bowen, D. H., "Runoff Poses Next Big Control Challenge," Environ-
mental Science & Technology, Vol. 6, No. 9, p. 771, Sept. 1972.
3. Eckenfelder, W. W., Industrial Water Pollution Control, McGraw-Hill
Book Company, New York, 1966.
4. O'Connor, D. J., and W. E. Dobbins, "The Mechanism of Reaeration
in Natural Streams," Jour, of the Sanitary Division, ASCE, Vol. 82,
No. SA6, Dec. 1956.
5. O'Melia, C. R., Chapt. 2, "Coagulation and Flocculation," Physio-
chemical Processes for Water Quality Control, Walter J. Weber,
Editor, Wiley Interscience, New York, 1972.
6. Chemical Treatment of Combined Sewer Overflow, Report #11023 FOB,
Sept. 1970, Environmental Protection Agency, Water Quality Office,
Washington, D. C.
7. Storm Water Management Model, Vol. Ill - User's Manual, Report No.
11Q24-DOC-09/71, Environmental Protection Agency, Water Quality
Office, 1971.
8. Standard Methods for the Examination of Water and Wastewater, 13th
Edition, American Public Health Assn., Inc., 1740 Broadway, New
York, N. Y., 1971.
117
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SECTION XII
GLOSSARY
GENERAL
CFS
EPA
GPD
GPM
HRS
MG/L
NC
Q
SWMM
USGS
°C
#/ml
CHEMICAL
Al
ALK
BOD
Ca
Co
COD
Cr
Cu
Fe
FC
JTU
K-N
Mg
Mn
Ni
Pb
Sr
SS
TOC
Total-?
TS
VS
VSS
Zn
Cubic feet per second
Environmental Protection Agency
Gallons per day
Gallons per minute
Hours
Milligrams per liter
North Carolina
Discharge rate
EPA Storm Water Management Model
United States Geological Survey
Degrees centigrade
Number per milliliter
Aluminum
Alkalinity
Biochemical Oxygen Demand
Calcium
Cobalt
Chemical Oxygen Demand
Chromium
Copper
Iron
Fecal Coliform
Jackson Turbidity Units
Kjeldahl Nitrogen
Magnesium
Manganese
Nickel
Lead
Strontium
Suspended solids
Total Organic Carbon
Total Phosphorus
Total Solids
Total Volatile Solids
Volatile Suspended Solids
Zinc
118
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SECTION XIII
APPENDIX
Page
Time Parameters and Analytical Results of Urban Runoff
Events Number 1 through 36 120-146
Third Fork Creek Base Flow Observations at USGS Gage
House and Sub-basins 147-152
Time Parameters and Analytical Results of Urban Runoff
Events Monitored at Sub-basin Discharge Locations 153-157
119
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Table 27. TIME PARAMETERS AND ANALYTICAL RESULTS
OF URBAN RUNOFF EVENT NUMBER 1
Date: 10/23/71
Time (hrs) From
Storm
Start
13.0
13.2
13.5
13.8
14.0
14.2
14.5
14.8
15.0
15.2
15.5
15.8
16.0
16.2
16.5
Last
Storm
91
91.2
91.5
91.8
92
92.2
92.5
92.8
93
93.2
93.5
93.8
94
94.2
94.5
Last
Peak
1.0
1.2
1.5
1.8
2.0
2.2
2.5
2.8
3.0
3.2
3.5
3.8
4.0
4.2
4.5
Q
CFS
111
88
78
58
58
64
65
67
66
52
44
36
31
25
23
Organics
mg/1
COD
7
14
14
14
4
12
28
32
36
48
36
36
36
40
BOD
8
5
5
20
2
3
42
25
31
30
14
33
Nutrient i
mg/1
K-N
.80
.89
.93
1.00
.99
1.09
.82
.87
.86
.94
.82
.77
1.02
1.01
.94
Total f
.22
.24
.28
.28
.28
.26
.40
.28
.26
.26
.38
.28
.28
.26
.28
Solids
mg/1
Total
234
221
215
281
201
19.4
221
241
SS
160
115
40
95
85
45
90
80
Metals
Co
.37
.35
.45
.43
.42
.44
.41
.33
.47
.17
.44
.37
.21
.23
.41
Cn
.39
.39
.49
.50
.34
.28
.38
.40
.48
.13
.23
.45
.39
.34
.58
Fe
5.6
6.2
5.0
6.0
6.4
3.6
3.5
5.2
3.2
3.2
3.0
3.9
3.2
2.9
4.5
Zn
.14
.10
.15
.11
.13
.60
.90
.11
.10
.60
.11
.70
.11
.15
.14
Table 28. TIME PARAMETERS AND ANALYTICAL RESULTS
OF URBAN RUNOFF EVENT NUMBER 2
Date: 11/24/71
Time (hrs) From
Storm
Start
.1
.2
.5
.6
.7
1.0
1.2
1.5
1.6
1.7
1.8
1.9
1.9
Last
Storm
506
506
507
507
507
507
508
508
508
508
509
509
509
Last
Peak
506
506
507
507
507
507
508
.2
.4
.5
.7
.8
.8
Q
CFS
.5
.8
.9
8.5
9
9.8
18
18
14
13
13
13
13
Organics
mg/1
COD
168
264
244
316
232
276
392
256
284
277
169
191
310
TOC
47
48
55
27
60
58
89
45
46
77
38
40
46
Nut
m
K.-N
8.2
12.0
8.6
9.6
10.2
8.6
7.0
8.4
7.9
8.4
8.4
10.8
11.6
rients
g/1
Total P
.94
1.14
.72
.60
.52
.53
.54
.58
.60
.44
.48
.45
.36
Solids
mg/1
Total
430
505
555
470
560
850
555
765
445
425
345
545
SS
50
105
180
115
280
630
365
475
300
235
225
330
Metals
Co
.15
.20
.07
.05
.11
.10
.06
.08
.10
.06
.15
.04
.14
Cr
.27
.43
.31
.25
.25
.25
.45
.32
.38
.30
.23
.33
.38
Cu
.13
.18
.18
.08
.15
.12
.16
.13
.20
.10
.12
.12
.13
Fe
2.5
5.0
3.2
2.7
3.5
2.4
4.8
3.3
4.1
3.3
3.2
4.0
3.6
Mn
.58
.84
.64
.61
.69
.63
.65
.64
.52
.42
.57
.45
.52
Ni
.25
.15
.13
.15
.22
.20
.12
.12
.16
.15
.21
.16
.09
Pb
.41
.40
.48
.38
.40
.73
.48
.40
.60
.44
.45
.50
.72
Zn
.16
.31
.21
.21
.21
.17
.23
.19
.23
.17
.13
.20
.15
120
-------
Table 29. TIME PARAMETERS AND ANALYTICAL RESULTS
OF URBAN RUNOFF EVENT NUMBER 3
Date: 12/16/71
Time (hrs) From
Storm
Start
.1
.25
.5
.75
1.0
1.25
1.5
1.75
2.0
2.25
Last
Storm
97.2
97.5
97.8
98
98.2
98.5
98.8
99
99.2
99.5
Last
Peak
97.2
97.5
97.8
98
98.2
98.5
.2
.5
.8
1.0
Q
CFS
1
1
2
2
3
3
2
2
2
2
Organlcs
mg/1
COD
157
112
134
112
99
96
80
99
115
109
TOC
47
32
27
28
23
25
27
30
27
30
Nutrients
mg/1
K-N
7.2
10.4
8.0
L0.8
7.6
5.7
6.8
6.S
19.0
L3.0
Total f
.48
.4
.46
.5
.42
.43
.32
.37
.56
Fecal
Coliforms
///ml
505
440
232
151
111
145
145
110
90
100
Solids
rag/1
Total
810
730
480
410
425
SS
305
175
100
95
140
Metals
mg/1
Co
.06
.09
.17
.10
.04
.13
.06
.11
.05
..08
Cr
42
.46
.42
.29
.27
.33
.32
.18
.29
.35
Cu
.12
.15
.13
.13
.09
.06
.07
.13
.12
.10
Fe
7.7
5.0
5.3
3.6
3.4
2.8
2.4
2.4
2.9
2.2
Mn
1.24
,1.13
.80
.69
.44
.52
.60
.57
.60
.58
Ni
.22
.17
.15
.17
.20
.22
.13
.19
.11
.13
Pb
.48
.40
.46
.50
.42
.43
.32
.37
.56
Zn
.33
.33
.23
.18
.15
.13
.12
.11
.11
.09
pH
6.9
7.0
7.0
7.0
7.0
7.0
6.9
6.9
7.0
7.0
Table 30. TIME PARAMETERS AND ANALYTICAL RESULTS
OF URBAN RUNOFF EVENT NUMBER 4
Date: 12/20/71
Time
Storm
Start
8.5
8.7
8.8
9.0
9.3
9.7
10.0
10.3
10.7
11.0
11.3
11.7
12.0
12.3
12.7
13.0
(hrs) F
Last
Storm
81.0
81.2
81.3
81.5
81.8
82.2
82.5
82.8
83.2
83.5
83.8
84.2
84.5
84.8
85.1
85.5
rom
Last
Peak
.5
.7
.8
1.0
1.3
1.7
2.0
2.3
2.7
3.0
3.3
3.6
.3
.7
1.0
1.3
Q
CFS
23
22
19
17
11
9
7
7
7
8
16
15
12
11
11
11
Organics
mg 1
COD
220
234
216
176
230
154
194
154
183
183
216
128
100
115
127
111
TOU
42
33
54
28
42
39
28
28
28
38
38
39
27
37
34
41
Nutrients
mg/1
K-N
7.6
17.8
7.6
14.8
13.2
6.6
9.3
6.2
7.2
7.4
13.2
12.8
7.8
8.8
9.2
5.4
0-otao. r
.55
.20
.65
.70
.33
.45
.50
.45
.34
.50
.60
.40
.48
.46
.63
.35
Fecal
Coliforms
n /_i
If /TILL
235
425
565
465
490
505
480
395
310
375
280
425
540
310
290
285
Co
.11
.20
.05
.22
.17
.17
.10
.14
.19
.17
.21
.11
.14
.16
.14
.04
.44
.28
.29
.37
.18
.39
.28
.22
.31
.31
.38
.30
.27
.38
.28
.30
Cu
.18
-.18
.17
.18
.09
.12
.11
.16
.14
.11
.12
.12
.11
.14
.18
.11
Met£
mg
Fe
11.4
12.9
10.6
14.6
9.3
7.3
6.9
6.9
11.4
6.8
8.0
13.6
10.7
14.7
9.9
14.3
ils
1
Ni
.11
.15
.17
.19
.17
.19
.20
.17
.21
.22
.15
.18
.29
.17
.15
.22
Mn
.79
.71
.85
.78
.49
.53
.55
.53
.44
.60
.65
.48
.59
.63
.53
.60
Pb
.70
,58
.60
.50
.50
.44
.50
.50
.40
.50
.56
.54
.45
.70
.68
.46
Zn
.53
.35
.43
.31
.26
.27
.25
.32
.29
.30
.40
.27
.18
.37
.33
.30
121
-------
Table 31. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 5
Date: 1/4/72
lime (hrs) From
Storm
Start
.5
.8
1.3
2.4
2.7
3.1
3.4
3.7
Last
Storm
115
115.3
115.8
116.9
117.2
117.6
117.9
118.2
Last
Peak
115
.1
.5
1.6
1.9
2.3
2.6
2.9
Q
CFS
6
25
13
14
11
8
6
5
Organics
mg/1
COD
200
320
228
144
120
84
104
92
TOC
66
109
43
25
11
10
14
31
BOD
26
42*
28
14
18
18
4**
7
Nut
m
K-N
1.6
1.3
1.2
1.2
rients
B/l
Total P
1.2
2.5
.65
.37
Fecal
Coliforms
if ml
235
150
895
315
635
495
270
330
Solids
mg/1
Total
920
645
415
355
SS
690
550
280
190
Metals
mg/1
Ca
8.69
5.63
2.89
2.13
3.44
3.34
4.05
Cr
.27
.34
.27
.27
.3
.24
.28
Fe
9.5
15.5
13.4
11.6
8.8
7.1
8.4
7.0
Mg
12.0
21.8
11.1
10.9
7.3
8.2
8.2
Mn
.81
1.15
.81
.52
.52
.42
.46
.44
Pb
.90
.88
.85
.49
.54
.41
.42
.49
Zn
.36
.63
.45
.31
.28
.22
.25
.21
pH
7.04
6.89
6.77
7.00
6.85
6.81
7.33
7.23
* Less than 1.5 mg/1 D.O. remaining
** Less than 1.0 mg/1 D.O. uptake
-------
Table 32. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 6
Date: 1/10/72
ro
to
Time (hrs) From
Storm
Start
2.0
2.3
2.7
3.0
3.3
3.7
4.0
4.3
4.6
5.1
5.6
6.1
6.6
7.1
7.6
8.1
8.6
9.1
Last
Storm
13.0
13.3
13.6
14.0
14.3
14.7
15.0
15.3
15.6
16.1
16.6
17.1
17.6
18.1
18.6
19.1
19.6
20.1
Last
Peak
13.0
13.3
.7
1.0
1.3
1.6
2.0
.3
.7
1.2
1.7
2.2
.5
1.0
1.5
2.0
2.5
3.0
q
CFS
16
20
19
17
15
15
26
38
27
22
30
'83
61
2~6
13
9
7
5
Organics
mg/1
COD
140
132
108
112
92
92
92
116
128
144
144
236
268
288
152
120
84
80
TOC
30
27
28
18
19
13
13
18
20
26
48
44
44
29
17
17
18
BOD
7
5
5
9
11
12
13
14
17
20
23
27
41
51
15
11
13
25
Nutrients
mg/1
K-N
1.6
1.7
1.8
1.8
1.8
2.5
3.0
1.9
1.4
Total P
.76
.72
.54
.62
1.28
.56
1.29
.59
.47
Fecal
Colif onus
t/mi
850
700
650
700
650
650
550
650
600
550
750
750
850
950
650
600
650
550
Solids
mg/1
Total
610
690
555
555
470
445
425
505
660
675
605
1205
1540
1080
720
595
460
385
SS
460
535
375
305
290
230
275
395
475
510
395
920
1135
870
485
430
250
195
Metals
ms/1
Ca
2.77
3.71
2.40
2.60
2.60
2.35
2.21
2.26
2.53
2.37
1.88
1.91
2.16
2.08
2.51
3.13
3.56
Cr
.29
.27
.30
.36
.30
.21
.24
.34
.38
.25
.30
.29
.25
.30
.26
.28
.27
Fe
9.9
8.2
11.0
9.8
' 7.2
7.8
9.7
13.3
12.3
9.3
17.9
21.7
15.3
13.1
9.8
6.8
7.1
Mg
9.1
9.6
9.7
8.0
7.0
6.6
7.6
12.0
10.0
7.4
10.6
13.4
13.2
9.2
10.0
6.3
8.0
Mn
.54
.65
.51
.47
.39
.43
.56
.83
.65
.62
1.18
1.14
-.73
.64
.58
.43
.42
Pb
.53
.37
.28
.34
.31
.37
.35
.35
.41
.33
.74
.67
.56
.41
.38
.21
.23
Zn
.26
.21
.20
.15
.14
.20
.20
.35
.27
.23
.37
.53
.41
.27
.24
.14
.16
-------
Table 33. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 7
Date: 2/1/72
Time (hrs) From
Storm
Start
.5
1.0
1.5
2.5
3.0'
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
Last
Storm
285
285
286
287
287
288
288
289
289
290
290
291
291
292
292
293
293
294
294
295
295
296
Last
Peak
285
285
286
1.0
1.5
2.0
2.5
3.0
3.5
4.0
.5
.3
.8
1.3
.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Q
CFS
3
28
96
102
84
75
81
90
110
113
116
112
111
138
118
95
76
49
32
22
15
11
Organlcs
rcg/1
TOD
322
473
442
186
153
125
184
125
145
161
125
148
182
163
156
272
97
225
144
272
99
91
TOC
115
143
140
46
16
12
38
12
41
28
16
31
28
13
24
10
9
28
16
8
8
7
BOD
20
2
3
7
5
8
5
6
Fecal
Coliforms
If/ml
145
135
325
60
90
60
65
15
70
130
135
75
175
65
140
165
115
105
115
45
5
Nutrients
mg/1
K-N
2.2
1.0
.4
.3
f i
.5
.2
.3
.3
.8
1.1
Total P
4.1
1.55
.67
.53
.57
.63
1.21
.95
.53
.57
.5
Solids
mg/1
Total
985
2725
1375
1285
1500
-1910
1330
1545
2265
1850
1660
SS
660
2640
1295
1180
770
1810
1335
1405
1625
1665
1660
Metals
mg/1
Ca
6. .8
3.8
1.9
1.5
2.1
2.0
1.8
1.8
1.6
1.5
1.9
1.9
1.8
1.8
1.9
1.8
2.4
2.8
3.1
4.7
5.0
6.0
Cr
.47
.36
.45
.41
.13
.23
.33
.32
.34
.21
.35
.21
.36
.26
.34
.21
.08
.25
.31
.29
.28
.23
Fe
20.0
19.6
25.6
15.8
12.4
9.7
9.7
10.0
10.8
10.1
9.1
11.4
11.2
11.4
11.3
11.4
7.3
8.4
8.1
6.4
6.6
5.2
Mg
10.8
16.4
20.8
10.6
6.8
6.9
6.0
6.7
7.5
7.5
6.6
7.2
9.6
9.6
9.7
7.3
6.1
8.0
8.4
8.3
8.1
11.7
Mn
1.68
1.54
1.48
.79
.64
.48
.45
.53
.61
.66
.59
.57
.68
.66
.68
.51
.36
..45
.45
.46
.48
.46
Pb
1.14
.68
1.12
.61
.71
.32
.36
.53
.47
.46
.43
.31
.27
.57
.37
.47
.28
.26
.27
.34
.21
.16
Zn
.70
.84
.88
.42
.30
.24
.24
.30
.26
.31
.26
.34
.32
.35
.30
.32
.19
.29
.24
.17
.20
.22
Ph
7.3
7.0
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.1
7.0
7.0
7.0
7.1
7.0
7.1
7.2
7.1
7.2
7.2
7.2
7.4
-------
Table 34. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 8
Date: 2/12/72
01
Time (hrs) From
Storm
Start
4.5
5.0
5.5
6.0
6.25
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
17.0
17.5
18.0
Last
Storm
220
220.5
221
221.5
221.7
222
222.5
223
223.5
224
224.5
225
225.5
226
232.5
233
233.5
Last
Peak
220
220.5
221
221.5
.0
1.0
1.5
2.0
2.5
3
3.5
.3
.8
1.3
7.5
8.0
8.5
Q
CFS
3
23
34
38
36
33
31
23
18
27
76
76
63
39
17
16
13
Organics
mg/1
COD
283
198
141
98
169
133
118
94
112
221
255
149
423
47
43
43
TOC
39
45
41
32
40
26
25
26
19
55
51
39
67
18
20
20
Fecal
Coliforms
Ill/ml
168
137
75
58
92
80
53
55
70
55
48
109
115
58
87
69
48
Nutrients
mg/1
K-N
.6
.5
.2
.2
.5
1.0
.4
Total P
.48
.59
.37
.44
.93
.98
.33
Solids
mg/1
Total
2160
1420
1500
670
2500
2020
1520
1420
2460
2210
2570
2140
340
290
305
SS
1880
1040
1390
510
2120
1780
1430
1020
2750
2060
2620
2000
115
115
110
Metals
mg/1
Ca
3.6
2.7
2.8
2.6
1.7
2.1
2.2
2.5
2.7
2.1
1.9
1.9
4.0
3.6
5.1
4.6
Cr
.24
.11
.09
.25
.26
.23
.27
.30
.34
.24
.25
.35
.23
.30
.32
.30
Fe
28.8
12.9
11.4
9.8
13.4
9.9
8.8
6.6
7.4
12.6
17.6
12.8
12.3
4.6
2.7
4.0
Mg
16.4
12.4
10.4
9.2
9.8
9.4
6.1
5.6
7.1
6.8
11.4
11.0
14.6
6.1
6.0
6.5
Mn
1.45
.65
.50
.41
.62
.54
.45
.30
.43
.62
.84
.64
.64
.33
.26
.25
Pb
.74
.70
.60
.46
.51
.32
.29
.40
.36
.52
.63
.50
.57
.27
.24.
.24
Zn
.76
.41
.36
.24
.29
.29
.18
.17
.21
.31
.49
.35
.35
.13
.15
.10
pH
7.5
7.0
7.2
7.0
7.3
7.0
7.1
7.2
7.1
7.1
7.1
7.2
7.3
6.9
6.9
6.8
-------
Table 35. TIME PARAMETERS AND ANALYTICAL RESULTS
OF URBAN RUNOFF EVENT NUMBER 9
Date: 2/18/72
Time hrs) From
Storm
.1
.5
1.0
1.5
2.0
2.5
3
3.5
4
4.5
5
6
6.5
7
7.5
8
8.5
9.5
10
11
11.5
Last
135
136
136
137
137
138
138
139
139
140
140
141
142
142
143
143
144
145
145
146
147
Last
135
135
.5
1.0
.5
1.0
1.5
2.0
2.5
3.0
3.5
4.5
5.0
.5
1.0
1.5
2.0
3.0
3.5
4.5
5.0
Q
CFS
3
24
26
29
20
16
12
7
6
6
7
22
24
23
23
21
20
16
14
10
9
Organics
mg/1
CQj) TAT
454
282
165
161
133
94
90
82
79
79
115
226
83
123
87
459
87
79
63
67
123
70
30
24
10
16
22
21
19
20
13
Fecal
Coliforms
tf/ml
164
197
77
61
56
91
71
39
31
24
80
30
35
30
33
36
26
26
10
6
115
Nut
n
K-N
.7
.3
.7
.3
.9
1.7
.2
.4
.6
.6
rients
S/l
Total P
1.70
.60
.44
.36
.32
.47
.29
.33
.25
.30
Sol
mo
SS
3730
1620
1050
1340
3000
850
490
530
970
2090
3620
Ids
11
vss
340
95
50
25
20
80
25
30
35
50
75
Ca
3.8
3.0
2.1
2.0
2.3
2.6
2.2
3.1
3.3
4.6
6.0
4.8
4.7
4.8
5.3
4.9
4.8
4.3
4.8
5.1
6.6
Fe
24.6
13.5
13.1
15.. 1
12.4
8.8
9.0
8.4
7.5
6.7
10.3
6.4
8.6
6.7
7.0
8.9
5.6
5.8
4.2
4.0
5.0
Metal
mR/l
Mg
14.8
11.1
10.7
9.0
9.2
8.7
7.9
7.6
7.2
8.7
8.8
6.5
6.5
6.2
7.1
7.4
6.4
6.7
5.9
5.6
9.3
3
Mn
1.04
.75
.63
.55
.62
.43
.47
.43
.57
.71
.59
.49
.37
.52
.47
.48
.39
.42
.28
.38
.47
Pb
1.09
.86
.74
.47
.55
<.l
.35
.24
.29
.30
.32
.36
.29
<.l
.36
.40
.10
.25
<.l
<.l
.15
Zn
4.58
.97
.96
.66
.55
.44
.44
.37
.39
.39
.47
.43
.53
.52
.44
.53
.41
.33
.27
.30
.31
pH
7.0
6.9
7.2
7.3
7.3
7.4
7.1
7.3
7.3
7.4
7.
Table 36. TIME PARAMETERS AND ANALYTICAL RESULTS
OF URBAN RUNOFF EVENT NUMBER 10
Date: 2/23/72
Time (hrs) From
Storm
Start
.1
1
2
3
4
Last
Storm
111
112
113
114
115
Last
Peak
111
112
113
1
2
Q
CFS
1
1
16
7
4
Organics
mg/1
COD
47
63
286
137
90
TOC
8
22
75
52
24
Fecal
Coliforms
;? /ml
36
53
108
80
57
Nutrients
mg/1
K-N
.4
.7
.7
.6
.6
Total P
.53
.44
1.03
.46
.4
Solids
mg/1
Total
455
765
1435
1035
1220
SS
70
215
725
755
1095
Metals
mg/1
Ca
31.2
28.4
3.5
3.8
4.7
Fe
2.8
5.S
13.1
9.6
7.6
Mg
14
15.2
10
7.8
9.2
Mn
.67
.75
.77
.62
.42
Pb
.29
.22
.96
.59
.32
Zn
.33
.38
1.08
.62
.52
pH
7.7
7.6
7.2
7.3
7.4
126
-------
Table 37. TIME PARAMETERS AND ANALYTICAL RESULTS
OF URBAN RUNOFF EVENT NUMBER 11
Date: 2/26/72
Time (hrs) From
Storm
Start
.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
10.5
11
Last
Storm
68
68.5
69
69.5
70
70.5
71
71.5
72
72.5
73
73.5
74
74.5
75
75.5
76
76.5
77
77.5
78
78.5
Last
Peak
68
68.5
.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
Q
CFS
18
20
13
7
4
3
3
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
Organics
rag/1
COD
714
407
326
241
167
159
140
140
123
77
108
88
115
104
104
115
111
104
127
104
115
71
TOC
104
46
45
35
19
35
29
16
24
28
17
Nutrients
mg/1
K-N
.7
.5
.5
.4
.5
.8
.9
.6
1.1
1.3
1.1
Total P
1.95
1.40
1
.7
.77
.76
.77
1.15
1.1
.95
1.1
Solids
mg/1
Total
2310
1455
1275
1105
585
1245
1115
950
825
1190
. 800
SS
3505
2295
2030
1350
895
1050
725
895
590
360
475
700
710
800
760
750
575
575
785
775
795
390
Metals
n.R/1
Ca
2.5
3.0
3.2
4.1
4.5
5.6
6.9
7.7
7.8
8.0
14.8
Fe
54.7
31.4
19
11.5
10.6
8.4
9.1
9.8
7.9
8.7
8.2
Mg
24
16.4
12
12.9
11.3
11.4
12.4
14.8
14.7
18.1
19.5
Mn
2.11
1.27
.89
.75
.67
.7
.68
.63
.66
.78
.7
Pb
2.86
1.06
.42
.47
.21
<.l
.19
.3
.36
.22
.17
Zn
3.36
1.83
.91
.71
.63
.51
.58
.53
.49
.54
.53
pH
7.2
7.2
7.2
7.2
7.3
7.4
7.5
7.5
7.6
7.6
7.5
127
-------
Table 38. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 12
Date: 3/8/72
00
Time (hrsj From
Storm
Start
.5
.8
1.2
1.5
1.8
2.2
2.5
2.8
3.2
3.5
3.8
4.2
4.8
5.2
Last
Storm
278
278.3
278.7
279
279.3
279.7
280
280.3
280.7
281
281.3
281.7
282.3
282.7
Last
Peak
278
278.3
.3
.7
1
1.3
1.7
2
2.3
2.6
3
3.3
4
4.3
Q
CFS
3
4
4
4
4
3
3
2
2
2
1
1
1
1
Organlcs
ng/1
COD
163
136
120
116
97
93
74
66
47
66
43
43
47
43
TOC
47
44
32
39
36
32
17
BOD
35
23
17
12
11
7
2
Fecal
Conforms
t/ml
253
151
136
128
116
109
147
117
73
70
42
35
31
17
Nutrients
mg/1
K-N
.8
.6
.9
.6
.7
.5
.5
Total P
1.2
1.0
.85
.55
.6
.75
.75
Soltds
IUR/1
TS
480
455
405
330
305
370
390
VS
90
85
105
70
52
82
60
TSS
205
205
200
200
140
145
85
80
55
135
120
95
135
250
vss
30
25
15
25
10
20
10
15
10
5
5
10
Metals
mg/1
Ca
17.6
28.9
23.7
19.4
24.6
30.5
28.3
Fe
5.4
4.4
4.2
3.2"
2.9
2.9
3
Mg
10.4
7
7.2
9.8
11
10.6
10
Mn
.51
.36
.41
.48
.51
.47
.39
Pb
.25
.1
.35
.39
.35
.32
<.l
Zn
.31
.25
.3
.21
.17
.17
.13
pH
7.4
7.3
7.2
7.4
7.2
7.5
7-5
-------
Table 39. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 13
Date: 3/16/72
Time (hrs) From
Storm
Start
1.0
1.3
1.7
2.0
2.3
2.7
3.0
3.3
3.7
4.0
4.3
4.7
5.0
5.3
5.7
6.0
6.3
6.7
7.0
7.3
7.7
8.0
8.3
Last
Storm
200
200
201
201
201
202
iOJ.
202
203
203
203
204
204
204
205
205
205
206
206
206
207
207
207
Last
Peak
200
200
201
201
.3
.7
1.0
1.3
1.7
2.0
2.3
2.7
3.0
3.3
3.7
4.0
4.3
4.7
5.0
5.3
5.7
6.0
6.3
Q
CFS
3
20
38
44
38
29
17
13
8
6
4
3
2
2
2
2
2
2
3
3
4
14
41
Organlcs
mg/1
COD
353
596
404
306
194
145
124
98
82
67
66
59
78
«4
62
59
101
93
105
97
98
380
283
TOC
18
97
42
28
26
26
35
23
37
49
109
BOD
40
32
30
20
7
6
13
5
8
16
23
32
Nut
m
K-N
1.1
.2
.6
.7
.6
.6
.6
.6
.7
.6
.4
rients
R/l
Total P
1.6
1.0
.60
.70
.35
.35
.40
.37
.41
.39
1.30
Fecal
Coliforms
///ml
125
197
174
349
79
159
152
133
112
116
98
107
91
59
54
66
93
131
163
94
95
272
225
Solids
MR/I
Total
1840
1070
700
560
360
410
990
650
710
620
2130
VS
380
300
180
150
140
120
190
180
210
180
330
ss
680
1670
920
990
650
640
530
530
280
310
290
360
350
890
280
490
330
490
370
490
890
2160 .
1220
vss
160
280
250
180
130
120
110
80
90
60
70
60
60
80
80
70
80
70
70
60
140
250
180
Metals
mR/1
Ca
6.1
3.9
4.0
4.2
5.3
5.8
6.5
7.4
6.4
5.3
3.4
Fe
33.9
20.9
15.1
10.5
6.7
6.2
7.4
6.3
7.3
7.4
27.5
Mg -
12.4
8.4
7.4
6.4
6.3
5.2
8.0
9.6
5.0
4.8
18.0
Mn
1.20
.69
.55
.46
.30
.28
.32
.33
.41
.27
.85
Pb
.73
.74
.33
.39
.35
.10
,13
<.l
.25
.17
.94
Zn
1.03
.62
.25
.28
.15
.10
.22
.12
.30
.25
.68
pH
7.0
6.9
6.9
7.0
7.2
7.2
7.3
7.3
7.2
7.1
7.0
-------
Table 40. TIME PARAMETERS AND ANALYTICAL RESULTS
OF URBAN RUNOFF EVENT NUMBER 14
Date: 3/31/72
Time (hrs) From
Storm
Start
.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
li.o
11.5
Last
Storm
240
240
241
241
242
242
243
243
244
244
245
245
246
246
247
247
248
248
249
249
250
250
251
Last
Peak
240
240
241
.3
.8
1.3
1.8
2.3
2.8
3.3
3.8
4.3
4.8
.5
1.0
1.5
2.0
2.5
3.0
3.5
4.5
4.5
5.0
Q
CFS
3
11
21
21
16
9
7
7
7
7
7
9
41
30
17
10
6
5
4
4
4
4
5
Organics
mg/1
COD
334
202
171
124
299
78
66
50
58
58
62
101
182
147
93
109
106
125
106
82
102
78
98
TOC
38
65
82
28
32
24
81
49
42
29
40
35
Solids
rag/1
Total
1010
1145
750
715
475
800
1785
1325
1765
1520
1080
VS
185
165
145
85
65
150
175
190
165
140
150
SS
1100
910
1010
1030
2095
655
610
575
485
325
545
700
1325
1730
1045
895
2020
1705
1450
1260
1435
770
1365
VSS
165
150
125
105
165
65
55
45
55
40
60
65
115
110
85
75
95
130
85
85
95
70
80
Metala
me/1
Ca
7.8
3.6
3.3
3.8
4.4
4.4
2.6
2.8
3.4
4.4
4.6
4.9
• Fe
11.7
11.1
5.4
6.3
5.7
4.3
15.8
12.9
8.9
10.0
8.6
11.5
Mg
13.4
6.8
11.2
5.4
6.0
5.6
9.8
8.2
8.8
8.6
10.4
9.6
Mn
.93
.45
.77
.27
.39
.17
.63
.42
.34
.27
.35
.28
Pb
.38
.44
.46
.16
.20
.13
.48
.30
c'.l
.20
.21
.48
Zn
.37
.27
.42
•31
.14
.13
.40
.26
.27
.18
.23
.23
pH
7.4
7.1
7.2
7.2
7.2
7.1
7.1
7.0
7.3
7.3
7.3
130
-------
Table 41. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 15
Date: 4/12/72
Time (hrs) From
Storm
Start
.8
1.3
1.8
2.3
2.8
3.3
3.8
4.3
4.8
5.3
6.3
6.8
7.3
7.8
Last
Storm
104
105
105
106
106
107
107
108
108
109
110
110
111
111
Last
Peak
104
.5
1.0
.5
1.0
1.5
2.0
2.5
3.0
3.5
4.5
5.0
5.5
6.0
Q
CFS
28
38
73
50
18
9
5
4
3
3
2
2
2
2
Orgaulcs
mg/1
COD
161
141
138
133
114
82
63
63
51
39
55
39
47
71
IOC
56
44
30
28
24
26
BOD
28
24
16
13
10
12
11
34
Solids
mg/1
Total
1195
1620
945
565
510
925
Vs
120
200
150
150
145
120
ss
775
1030
1555
1650
1060
805
505
420
350
345
395
700
1055
1115
vss
140
160
205
180
145
130
110
105
70
95
90
80
85
100
Metals
mg/1
Ca
3.9
2.2
2.4
3.5
4.7
7.0
12.8
Fe
9.5
13.9
7.0
11.8
4.9
1.3
5.3
Mg
8.2
9.4
6.6
6.6
6.6
8.4
8.4
Mn
.49
.65
.40
.21
.21
.20
.20
Pb
.40
.51
.11
.15
.18
.17
<.l
Zn
.28
.41
.27
.17
.14
.10
.11
pH
7.1
7.1
7.1
7.3
7.4
7.4
7.5
ALK
mg/1 as
CaCOj
34
26
47
60
-------
Table 42. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 16
Date: 5/3/72
OJ
NJ
Time (hrs) From
Storm
Start
.1
.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.5
8.0
8.5
9.0
9.5
10.5
11.0
Last
Storm
504
505
505
506
506
507
507
508
508
509
509
510
510
511
512
512
513
513
514
515
515
Last
Peak
504
505
505
506
.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
1.0
1.5
2.0
2.5
3.0
4.0
4.5
Q
CFS
1
19
43
72
63
50
43
27
24
21
18
16
41.
136
119
98
74
43
16
14
13
Organics
mB/1
COD
492
641
157
626
238
227
165
146
141
114
118
91
152
597
262
182
175
103
475
346
825
TOC
37
37
26
54
12
11
11
8
12
13
11
20
15
8
10
10
12
22
11
8
16
Nutrients
mp/1
K-N
1.3
2.1
0.7
0.1
0.4
0.4
0.5
0.4
0.4
0.5
Total P
1.2
2.4
1.2
.6
.4
.4
2.4
1.0
.4
.3
Fecal
Coliforms
i>/ml
63
66
72
240
160
150
160
130
130
120
150
130
110
160
180
200
190
130
170
140
150
Solids
mR/1
Total
4220
840
1290
1290
1510
840
1280
2230
3910
vs
320
140
180
160
120
130
150
250
190
ss
3400
7340
640
4040
1290
2310
1230
1700
1780
890
660
670
1360
7310
2430
2330
3700
5330
vss
170
320
90
300
140
200
130
130
80
40
40
60
50
47.0
220
100
130
110
Metals
mj»/l
Cr
.12
.18
.11
.41
.15
.17
.10
.10
.10
.10
<.l
<.l
<.l
.33
.25
.12
.10
<.l
.12
<.l
<.l
Cu
<.l
.17
<.l
.27
.10
.20
.10
.10
<.l
.10
<.l
<.l
.13
.29
<.l
<.l
.12
<.l
<.l
<.l
<.l
Pb
.40
.97
.13
.91
.55
.85
.13
.31
.27
.20
.19
.16
.24
2.06
.46
.34
.34
.10
.35
<.l
.12
Zn
.78
1.05
.27
1.28
.57
.77
.47
.34
.29
.27
.21
.18
.28
1.47
.65
.40
.33
.17
.32
.10
.33
pH
7.3
7.2
6.8
7.0
7.1
7.2
7.2
6.7
7.0
7.2
7.2
ALK
mg/1 as
CaCo3
138
24
32
28
-------
Table 43. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 17
Date: 5/14/72
OJ
U)
lime (hrs) From
Storm
Start
.1
.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
11.0
Last
Storm
254
255
255
256
256
257
257
258
258
259
259
260
260
261
261
262
262
263
263
264
264
265
265
Last
Peak
254
255
255
256
256
257
257
0.5
1.0
1.5
.5
1.0
1.5
2.0
2.5
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Q
CFS
1
2
2
2
2
33
41
20
36
105
63
23
11
47
63
22
10
7
6
6
6
5
4
Organics
mg/1
COD
939
120
124
128
120
198
124
70
82
136
147
116
109
85
85
182
144
85
81
89
89
66
TOC
31
18
28
34
25
26
12
12
11
9
7
9
8
12
9
6
7
9
12
14
14
14
14
BOD
71
53
39
37
40
34
39
39
36
36
Nutrients
mf>/l
K-N
.7
.9
.6
.4
.4
.3
.4
.3
.3
.3
.3
Total P
1.0
.44
1.0
.35
.50
.60
.45
.60
.55
.35
.35
Fecal
Coliforms
///ml
96
140
86
72
140
150
100
94
93
210
210
190
180
190
180
170
200
220
260
200
180
150
190
Solids
KIR/1
Total
1360
1455
1360
835
1395
1160
2415
2230
2175
1830
1195
vs
135
130
150
90
145
165
140
235
95
90
85
SS
930
915
1260
465
1440
1260
805
775
1325
1245
1070
1915
2730
1385
2275
1825
2255
2470
1795
2665
1220
vss
40
45
15
35
95
40
90
85
185
85
125
120
65
110
190
125
140
95
65
60
60
Metals
OK/1
CT
.20
<.l
.10
<.l
.11
.25
.14
.12
<.l
<.ll
.10
.11
<.l
<.l
<.l
.12
.12
<.l
<.l
<.l
<.l
<.l
<.l
Cu
.11
•e.l
<.l
.11
<.l
.12
<.l
<.l
<.l
.10
.13
<.l
<.l
<.l
<.l
<.l
<.l
•e.l
<.l
.10
<.l
<.l
<.l
Pb
.89
.21
<.l
<.l
.18
.40
.22
.13
.17
.32
.34
.14
<.l
.19
<.l
.40
.29
.25
.10
.38
.11
<.l
.13
Zn
.89
.26
.16
.15
.15
.44
.27
.21
.19
.34
.34
.24
.21
.21
.15
.23
.37
.22
.19
.16
.15
.11
.19
pH
7.4
7.3
7.2
7.1
7.0
6.9
6.8
6.8
6.9
7.0
7.0
6.8
6.9
7.0
7.2
7.1
6.9
7.1
7.1
7.2
7.3
7.6
7.6
ALK
mg/1 as
CaC03
132
76
26
18
14
20
28
46
-------
Table 44. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 18
Date: 5/22/72
Time (hrs) From
Storm
Start
2.3
2.8
3.3
3.8
4.3
4.8
5.3
5.8
6.3
Last
Storm
130
130
131
131
132
132
133
133
134
Last
Peak
2.0
2.5
3.0
0.5
1.0
1.5
2.0
2.5
3.0
Q
CFS
10
124
345
187
117
58
25
17
10
U1R/1
COD
51
35
31
35
39
50
43
47
39
TOC
24
23
12
12
16
13
17
14
10
Nutrients
mg/1
K-N
.3
.3
.3
.3
.3
.4
.3
.3
.3
Total P
.20
1.10
.34
.35
.79
.72
.60
.44
Fecal
Coliforms
///ml
4
4
2
2
5
6
4
4
1
Solids
mg/1
Total
3350
580
820
680
645
vs
135
100
100
110
90
SS
3770
295
245
360
560
755
395
900
365
vss
85
65
80
75
85
85
80
85
40
Metals
mg/1
Cr
<.l
<.l
<.l
<.l
<.l
Cu
<.l
<.l
<.l
<.l
<.l
Pb
<.l
<.l
<.l
<.l
<.l
Zn
.12
.10
.09
.10
.09
pH
7.8
7.8
7.8
7.7
7.7
ALK
mg/1 as
CoC03
122
114
122
Table 45. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 19
Date: 5/31/72
Time (hrs) From
Storm
Start
,5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Last
Storm
141
141
147
142
143
143
144
144
Last
Peak
141
.5
1.0
1.5
2.0
2.5
3.0
3.5
Q
CFS
30
15
12
4
2
2
1
1
Organlcs
mg/1
COD
367
232
142
106
92
96
56
62
TOC
92
65
40
36
32
26
14
27
BOD5
9
4
3
3
Nut
m
K-N
.7
1.0
.8
.8
rlents
?/l
Total P
1.1
.67
.39
.36
Fecal
Coliforms
///ml
1100
1000
400
350
200
170
160
160
Solids
mg/1
Total
1455
1090
995
425
VS
180
110
90
60
SS
2095
1245
820
895
575
910
275
375
VSS
245
130
75
70
35
45
30
25
Me
m
Co
<.l
<.l
<.l
<.l
Fe
23.3
9.8
14.7
3.7
tals
K/l
Mn
1.63
.49
.33
1.83
Ni
<.l
<.l
<.l
<.l
Pb
1.27
.40
.14
<.l
pH
7.2
7.2
7.4
7.5
ALK
rog/1
CaO>3
40
50
56
62
-------
Table 46. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 20
Date: 6/20/72
Ul
Time (hrs) From
Storm
Start
.1
.5
1.0
1.5
2.0
7.5
3.0
3.5
4.0
4.5
5.5
6.0
6.5
7.0
7.5
Last
Storm
494
495
495
496
496
497
497
498
498
499
500
500
501
501
502
Last
Peak
494
495
495
496
496
497
497
0.5
1.0
1.5
2.5
3.0
3.5
4.0
4.5
Q
CFS
1
1
1
1
1
4
75
19
11
5
3
3
4
3
2
Organics
mg/1
COD
359
294
171
127
196
353
605
247
135
147
116
137
149 ,
120
144
TOC
50
51
70
38
63
26
33
37
29
26
72
21
21
27
25
BOD
>74
>77
55
51
59
74
76
50
50
48
40
45
42
39
42
Nuti
m
K-N
1.4
1.4
1.0
.9
1.0
1.1
1.2
.8
.8
.6
.5
.7
.7
.5
.7
dents
5/1
Total P
1.60
.88
.47
.42
.53
3.0
3.5
1.2
.86
1.1
.57
.69
.59
.54
.50
Fecal
Coliforms
1! /ml
2000
810
440
370
120
1100
740
510
20
520
5
320
20
5
30
Solids
mg/1
Total
585
390
1130
1070
735
1310
875
VS
160
105
220
165
110
125
130
ss
530
115
175
2620
705
1060
1135
820
vss
95
65
70
375
125
95
110
100
Metals
mg/1
Co
<.l
<.l
<.l
<.l
<.l
<.l
<.l
•f.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
Fe
12.9
4.2
2.6
1.6
2.4
18.3
27.0
25.0
16.3
20.1
5.9
15.1
6.5
12.4
11.6
Mn
1.76
1.04
.61
.52
.59
2.31
2.25
1.07
.84
.64
.44
.58
.66
.54
.53
Ni
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
Pb
.56
.36
.35
.37
.17
.72
1.51
1.16
.46
.58 -
.18
.51
.26
<.l
.16
PH
7.5
7.1
7.1
7.2
7.3
7.1
ALK
ms/1
CaC03
98
42
45
-------
Co
Table 47. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 21
Date: 6/28/72
Time (hrs) From
Storm
Start
0.1
.5
1.3
1.5
2.0
Last
Storm
172
172
173
173
174
Last
Peak
172
172
173
.3
.8
Q
CFS
9
365
1740
L230
565
Organics
mg/1
COD
443
374
212
174
150
TOC
108
52
60
BOD5
146
102
96
92
90
Nutrients
mg/1
K-N
.9
.6
.4
.3
.3
NH.-N
4
.44
.05
.12
.'10
.12
N02+N0~
<.05
.52
.52
.32
.68
Total P
2.1
1.2
1.0
.86
.69
Fecal
Coliforms
///ml
300
340
320
450
400
Solids
mR/1
Total
2790
2130
VS
350
225
ss
2710
3960
2085
2350
2555
vss
280
305
265 .
215
135
Metals
mg 1
Cd
<.l
<.l
Mg
14.4
12.4
Mn
2.28
1.74
Zn
1.06
.62
Table 48. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 22
Date: 7/11/72
Time (hrs ) From
Storm
Start
.5
1.0
1.5
2.0
Last
Storm
157
158
158
159
Last
Peak
157
158
158
.5
Q
CFS
2
2
2
1
Organics
ms/1
COD
144
161
1043
260
TOC
92
62
384
122
BOD
64
66
84
78
Nutrients
mg/1
K-N
.4
.4
1.1
.7
Total F
.86
1.1
1.7
.86
Fecal
Colifonns
///ml
80
110
270
240
Solids
mg/1
Total
1430
2720
7940
3670
VS
220
240
L170
370
SS
930
2010
3230
3160
VSS
150
160
970
240
Metals
mg 1
Cd
<.l
<.l
<.l
<.l
Mg
12.9
12.3
13.5
10.8
Mn
.74
.64
.94
.53
Zn
.48
.44
.47
.33
pH
8.1
7.9
7.6
7.7
ALK
ng/1
CaCOj
124
124
94
102
-------
Table 49. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 23
Date: 7/12/72
Time (hrs) From
Storm
Start
1.3
1.8
2.3
2.8
3.3
3.8
4.3
4.8
5.3
5.8
6.3
6.8
7.3
7.8
8.3
Last
Storm
176
177
177
178
178
179
179
180
180
181
131
182
182
183
183
Last
Peak
176
.5
1.0
.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Q
CFS
29
25
36
23
15
9
7
8
8
4
3
2
2
1
1
Organics
mR/1
COD
219
175
134
101
74
64
65
105
113
84
111
76
80
20
21
TOC
110
42
43
48
25
40
27
56
25
26
26
32
35
18
14
BOD
110
96
100
100
96
98
100
104
Nutrients
mg/1
K-N
.5
.3
.2
.2
.2
.2
.2
.3
.3
.3 •
.2
.2
.3
.2
.2
Total P
1.0
.66
.66
• .39
.34
.31
.34
.42
.52
.36
.43
.32
.42
.28
.24
Fecal
Coliforms
ff/ml
660
290
320
280
280
310
250
260
120
240
290
350
240
200
110
Solids
rag/1
Total
720
655
360
965
715
1140
220
vs
190
190
135
170
180
190
120
ss
855
625
695
535
405
215
420
875
540
540
860
940
720
45
35
vss
115
65
40
35
30
0
20
35
35
15
45
20
20
0
0
Metals
mg/1
Cd
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
Mg
5.4
4.8
4.2
3.9
5.1
6.0
4.8
3.6
Mn
.95
.56
.31
.28
.41
.36
.29
.12
Zn
.43
.26
.14
.17
.29
.22
.19
<.l
pH
7.7
7.3
7.5
7.4
7.1
7.5
7.6
7.4
ALK
C3CO.J
40
26
36
40
-------
Table 50. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 24
Date: 7/17/72
LO
00
Time (hrs) From
Storm
Start
.3
.5
.8
1.0
1.3
1.5
1.8
Last
Storm
126
126
127
127
127
127
128
Last
Peak.
126
.1
.4
.1
.4
.6
.8
Q
CFS
112
112
88
125
82
25
17
Organics
COD
143
543
686
364
261
239
202
TOC
113
158
134
80
66
62
48
BOD
104
86
72
60
Nutrients
mg/1
K-N
.9
.4
.3
.2
.2
.2
.2
Total P
2.1
1.8
1.3
1.-3
1.1
1.2
1.2
Fecal
Conforms
#/ml
1300
330
680
470
190
420
450
Solids
mg 1
Total
4600
2885
3225
VS
595
395
465
ss
385
4445
3135
2900
3700
3150
2510
vss
65
465
380
300
400
345
270
Metals
mg/1
Cd
<.l
<.l
<.l
<.l
Mg
9.9
13.2
13.2
11.4
Mn
1.70
1.80
1.88
1.32
Zn
.26
.68
.64
.56
pH
7.9
7.2
7.0
7.0
ALK
mg/1
CaCOj
102
23
-------
Table 51. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 25
Date: 7/31/72
Time (hrs) From
Storm
Start
.3
.5
.8
1.0
1.3
1.5
1.8
2.0
2.3
2.5
2.8
3.0
3.3
3.5
3.8
4.0
4.3
4.5
4.8
5.8
Last
Storm
15
15
16
16
16
16
17
17
17
17
18
18
18
18
19
19
19
19
20
21
Last
Peak
15
15
16
.3
.5
.8
1.0
1.3
.3
.5
.8
1.0
1.3
1.5
1.8
2.0
2.3
2.5
2.8
3.8
Q
CFS
55
137
94
47
45
87
139
154
70
59
39
25
20
18
16
16
15
15
15
14
Organlcs
mg/1
COD
412
348
230
202
202
198
242
222
198
176
122
161
157
165
118
137
137
98
118
102
TOC
76
78
56
37
34
40
64
59
52
42
35
37
33
54
44
40
44
31
63
45
BOD
16
18
20
18
14
18
14
18
12
14
18
16
16
14
14
18
18
14
16
12
Nut
m
K-N
.3
.2
.2
.2
.2
.2
.3
.3
.3
.3
.4
.4
.4
.5
.5
.4
.5
.5
.5
.5
rlenta
E/l
Total P
.92
1.50
.86
.83
.66
.89
.72
.96
.78
.86
.54
.65
.66
.58
.56
.56
.61
.41
.61
.51
Solids
mg/1
Total
6040
5454
2830
2570
2820
354.0
3510
3600
3020
2850
1560
2390
2960
4150
2790
2260
2710
1910
2960
1680
VS
400
450
340
260
310
330
270
350
360
270
230
110
110
120
90
100
110
80
110
90
SS
6720
6270
3230
2920
3100
3980
3140
3620
3100
2970
1740
2430
3930
4810
2760
2600
2750
1670
2920
2080
VSS
220.
370
90
110
130
220
160
180
0
220
160
130
130
130
30
50
100
10
40
90
Metals
mg/1
Ca
3.0
2.2
1.8
1.6
1.8
1.6
1.5
1.1
1.4
1.6
2.2
2.0
2.4
2.5
2.8
3.1
3.2
3.5
3.7
4.1
Cr
.22
.19
.21
•C.I
.23
.18
.14
.22
.14
.16
.15
.10
<.l
<.l
C.I
.15
.10
<.l
.13
<.l
Cu
<.l
.18
<.l
.14
<.l
.13
<.l
.12
<.l
<.l
<.l
<.l
<.l
<.l
•c.l
•C.I
•C.I
<.l
<.l
<.l
Mg
11.4
10.8
8.8
6.8
7.6
11. 0
7.0
10.2
7.2
8.2
6.4
6.8
6.9
5.2
5.0
5.4
5.4
3.6
5.4
5.8
Zn
.61
.32
.50
.40
.43
.47
.46
.40
.33
.43
.32
.29
.28
.26
.25
.24
.31
.18
.28
.21
pH
7.5
7.3
7.6
7.4
7.3
7.4
7.6
7.6
7.7
7.7
ALJC
mg/1
CaC03
50
24
26
32
40
-------
Table 52. TIME PARAMETERS AND ANALYTICAL RESULTS
OF URBAN RUNOFF EVENT NUMBER'26
Date: 8/28/72
Time (hrs) From
Storm
Start
.5
.8
1.0
Last
Storm
220
220
221
Last
Peak
220
220
.5
Q
CFS
1
4
9
Organics
rag/1
COD
268
175
109
Soluble
COD
78
78
82
TOC
69
50
32
Solids
mg/1
Total
7300
6510
2460
VS
460
300
210
SS
5460
4890
1390
VSS
260
140
60
Table 53. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 27
Date: 9/17/72
Time
Storm
Start
.2
1.7
2.2
2.7
3.0
3.2
3.4
3.7
«.0
4.2
(hrs) From
Last
Storm
195
196
197
197
198
198
198
198
199
199
Last
Peak
195
196
.5
1.0
1.3
1.5
.2
.5
.8
1.0
Q
CFS
32
154
115
88
365
715
187
154
133
115
Organics
mg/1
COD
768
357
172
545
129
129
110
125
78
114
TOC
143
76
50
88
32
48
30
14
17
12
BOD.
71
37
30
32
29
25
99
30
30
28
Nutrients
mg/1
K-N
1.0
.6
.5
.4
.4
.4
.4
.4
.4
.4
Total P
2.0
1.2
.87
1.1
.68
.64
.55
.52
.46
.45
Fecal
Coliforms
///ml
780
220
160
100
100
80
60
80
20
120
Solids
mg/1
Total
6960
7460
2460
8620
1540
1430
1010
1120
1130
1270
VS
710
350
210
470
130
130
230
230
180
190
SS
6770
6750
2170
1440
1530
940
1000
940
1160
VSS
540
280
120
420
100
100
170
190
140
150
Metals
mg/1
Fe
55.3
58.7
24.2
44.7
31.6
25.3
25.4
19.6
21.1
22.7
Mn
3.24
1.61
1.07
2.57
.44
.92
1.33
.77
.63
.67
Pb
2.05
.88
.56
1.49
.37
.39
.71
.42
.25
.18
Sr
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
pH
7.0
6.6
6.8
6.7
6.7
ALK
mg/1
CaC03
18
16
-------
Table 54. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 28
Date: 9/21/72
Time (hrs) From
Storm
Start
.8
1.0
1.3
1.5
1.8
2.0
2.3
2.5
2.8
3.0
Last
Storm
85
85
86
86
86
86
87
87
87
87
Last
Peak
.1
.4
.6
.8
1.1
1.4
1.6
1.8
2.1
2.4
Q
CFS
39
36
32
24
21
10
9
8
7
5
Organics
mg/1
COD
279
213
144
124
105
112
89
101
97
136
Soluble
COD
92
73
61
61
65
65
65
61
61
100
TOC
20
18
13
18
12
13
12
31
30
47
Nutrients
mn/1
K-N
.3
.3
.7
.3
.3
.3
.3
.3
.2
Total P
.52
.39
.32
.37
.27
.35
.36
.35
Fecal
Coliforms
0/ml
400
250
300
260
230
250
200
180
180
230
Solids
mg/1
Total
1340
890
1050
620
1080
1110
890
1150
1510
1830
VS
170
150
170
120
120
130
240
130
120
120
ss
1180
790
970
470
980
890
680
1080
1400
1800
vss
90
30
80
80
50
40
50
60
120
90
Metale
mg/1
Fe
16.3
16.3
23.8
18.4
17.1
6.2
20.2
21.8
24.7
25.0
Mn
.77
.61
.82
.54
.43
.35
.40
.73
.66
.73
Pb
.44
.20
.20
.19
.26
.33
.15
.23
.34
.33
Sr
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
PH
7.2
7.4
7.3
7.3
7.3
ALK
mg/1
CaCOj
28
26
30
Table 55. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 29
Date: 10/5/72
Tine (hrs) From
Storm
Start
.1
.4
.7
1.1
1.4
1.7
2.2
Last
Storm
120
120
120
121
121
121
122
Last
Peak
120
120
.1
.4
.2
.3
.8
Q
CFS
63
325
169
455
270
169
270
Organics
mg/1
COD
202
229
109
155
147
85
70
TOC
40
68
BOD5
150
150
120
130
120
120
110
Nutrients
mg/1
K-N
.4
.3
.3
.2
.2
.2
.2
Total P
.72
1.20
.64
.61
.69
.58
.58
Solids
mg/1
Total
675
2680
1705
1795
1480
940
1135
VS
145
295
220
210
175
120
140
SS
460
2400
1590
1595
1335
870
1035
VSS
50
200
120
115
100
75
75
Metals
mg/1
Al
10.2
35.8
27.8
26.4
23.0
21.3
19.2
Ca
4.9
2.1
1.7
2.0
1.2
1.6
1.1
Cr
.12
.18
.14
.13
.23
.14
<.l
Cu
.11
.11
.15
<.l
<.l
.13
<.l
Mg
7.7
20.4
15.3
14.7
11.2
9.3
9.9
pH
7.2
6.8
7.0
7.1
ALK
CaCOj
43
14
-------
Table 56. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 30
Date: 10/19/72
Time (hrs) From
Storm Last Last
Start Storm Peak
Stage and
Precipitation
Recorders
Inoperable
Q
CFS
Organics
n.R/1
COD
300
242
188
207
157
119
104
108
111
111
84
TOC
53
54
46
73
38
27
42
32
38
32
44
BOD5
320
230
210
210
350
170
160
150
150
130
130
Nutrients
mg/1
K-N
.5
.6
.5
.7
.4
.4
.3
.4
.3
.4
.3
Total P
1.3
.71
.66
.76
.92
.54
.50
.57
.56
.81
.44
Fecal
Coliforms
///ml
160
80
40
100
100
120
80
100
120
90
40
Solids
mg/1
SS
870
520
610
800
4230
640
640
390
1250
1230
640
VSS
170
150
140
190
180
150
140
120
130
120
130
Metals
mg/1
Al
10.3
8.7
9.6
14.9
18.3
10.2
12.4
10.0
9.8
15.4
8.3
Ca
35.8
5.8
4.1
3.6
3.2
3.4
3.4
3.8
4.4
3.7
4.2
Cr
.14
<.l
.13
.10
.13
.21
<.l
<.l
<.l
.26
.11
Cu
<.l
.16
<.l
.10
.10
.10
<.l
<.l
<.l
<.l
<.l
MS
16.8
11.0
9.0
10.0
9.8
9.4
10.0
10.6
9.3
11.2
6.2
pH
7.4
7.0
7.1
7.1
7.3
7.2
ALK
mg/1
CaCOj
98
30
38
Table 57. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 31
Date: 11/14/72
Time (hrb) From
Storm
Start
.8
1.2
1.5
3.5
3.7
4.0
4.1
4.5
4.7
Last
Storm
141
141
142
144
144
144
144
145
145
Last
Peak
141
.5
.8
2.7
2.9
3.2
3.3
3.7
3.9
Q
CFS
112
80
96
28
25
18
17
14
8
Organics
mg/1
COD
303
223
169
81
104
73
85
61
88
TOC
74
72
58
43
42
33
44
34
40
BOD
210
170
150
34
34
30
30
34
24
Nutrients
mg/1
K-N
.4
.3
.3
.4
.3
.4
.3
.4
Total P
2.4
1.1
.83
.77
.61
.58
.52
.59
Fecal
Coliforms
0/ml
700
170
210
320
250
260
200
160
190
Solids
mg/1
Total
2300
1240
1560
780
920
510
660
440
1040
vs
360
300
240
220
250
200
230
190
190
SS
220
106
136
59
58
30
44
27
66
VSS
28
21
18
12
7
13
9
10
11
Metals
mg/1
Co
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
-------
Table 58. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 32
Date: 11/19/72
Time (hrs) From
Storm
Start
0.1
0.2
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
26
Last
Storm
59
59
60
60
61
61
62
62
63
63
64
64
65
65
66
66
67
67
68
85
Last
Peak
59
59
60
60
61
61
62
Q
CFS
2
4
5
7
7
8
9
8
7
6
6
8
10
12
14
13
10
43
73
3
Organics
mg/1
COD
268
105
109
112
62
66
58
58
74
70
62
194
101
74
109
78
350
136
78
35
TOC
33
37
34
38
33
26
15
30
31
22
21
57
37
38
36
50
49
34
30
22
Solids
rng/1
Total
700
578
906
614
576
479
405
612
703
408
1659
1510
1283
2176
878
1984
2726
600
309
VS
164
67
87
117
103
132
172
130
141
92
160
158
117
149
163
253
164
107
98
SS
347
286
674
344
442
303
118
318
342
127
1225
807
1005
1000
614
1759
2439
321
88
VSS
84
61
83
110
116
89
74
102
108
61
232
117
148
128
81
243
197
124
86
Metals
mg/1
Co
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
•e.10
<.10
<.10
<.10
Cu
<.10
<.10
<.10
<.10
<.10
<.10
<.10
•c.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
•c.10
<.10
<.10
<.10
Fe
17.0
15.6
18.5
16.9
20.8
12.0
12.8
18.2
14.0
18.4
10.7
44.5
35.5
16.0
17.8
19.7
29.5
26.5
20.3
4.3
Pb
.44
.30
.23
.35
.37
.22
.24
.22
.24
.14
.13
.42
.44
<.10
.14
<.10
.51
.36
.11
<.10
Zn
.72
.29
.24
.28
.29
.17
.17
.17
.20
.20
.14
.48
.27
.25
.27
.29
.52
.41
.17
.19
-------
Table 59. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 33
Date: 11/30/72
-p-
-t-
Time (hrs) From
Storm
Start
9.5
10.0
10.5
11.0
11.5
12.0
12.5
13.0
13.5
14.0
14.5
15.0
Last
Storm
111.0
111.5
112.0
112.5
113.0
113.5
114.0
114.5
115.0
115.5
116.0
116.5
Last
Peak
6.5
7.0
7.5
8.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Q
CFS
0.9
0.9
1.0
1.4
1.2
1.1
1.0
1.0
1.0
1.0
.9
.8
Organlcs
mg/1
COD
124
95
84
148
133
76
68
83
68
72
99
65
TOG
38
31
30
60
56
24
36
46
38
34
56
12
BOD
99
54
48
80
46
40
36
36
36
34
32
44
Nut
m
K-N
.3
.3
.2
.1
.2
.2
.2
.2
.2
.2
.2
rients
E/l
Total P
.59
.60
.46
i.io
.73
.53
.51
.67
.48
.53
.48
Fecal
Coliform
0/ml
32
28
29
54
96
51
55
32
22
23
62
45
Solids
mg/1
Total
1910
1868
790
2147
2020
1043
805
852
1450
1215
2219
1641
VS
269
263
257
325
320
257
187
218
222
235
289
277
SS
1416
1514
514
1803
1510
762
635
632
1704
710
1752
2006
vss
184
144
100
187
176
135
155
153
152
135
174
44
Metals
mg/1
Cd
<.10
<.10
<.10
<.10
<.10
<.10
<.10
-------
Table 60. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT-NUMBER 34
Date: 1/19/73
Time (hrs) From
Storm
Start
.05
.10
.15
.20
.25
.30
.35
.40
.45
.50
.55
.60
.65
.70
.75
.80
.85
.90
.95
1.00
1.05
1.10
1.15
1.20
1.25
1.30
Last
Storm
101
101.1
101.2
101.2
101.2
101.3
101.4
o-Oi.;
101.4
101.5
101.6
101.6
101.6
101.7
101.8
101.8
101.8
101.9
102.0
102.0
102.1
102.1
102.2
102.2
102.2
102.3
Last
Peak
101
101.1
101.2
101.2
101.2
101.3
101.4
101. 4
101.4
101.5
101.6
101.6
101.6
101.7
101.8
101.8
101.8
101.9
102.0
102.0
102.1
102.1
102.2
102.2
102.2
102.3
Q
CFS
3.0
3.2
3.2
3.0
2.9
2.9
2.9
2.9
3.0
3.2
3.3
3.3
3.5
3.5
3.6
3.8
4.5
4.7
5.2
5.5
8.5
L0.5
L8.0
L8.0
L8.0
JO.O
Organlcs
mg/1
COD
304
312
324
254
250
241
237
241
250
283
366
354
358
349
379
387
379
428
445
478
457
494
511
560
515
556
TOC
108
57
89
60
63
60
64
72
80
100
81
107
113
100
108
89
106
144
174
147
139
120
177
90
152
132
BOD
62
54
50
46
42
'42
40
40
42
38
42
36
38
38
40
42
42
48
52
58
62
62
68
74
70
66
Nutrients
mg/1
K-l
1.0
.7
.7
.8
.7
.6
.6
.5
.6
.6
.7
.9
.8
Total-P
1.9
2.5
1.0
1.1
1.0
1.2
1.2
1.3
1.2
1.9
1.7
2.4
1.7
Solids
DlR/1
Total
2351
5453
3646
1001
999
1025
1005
962
972
1204
1446
1470
1541
1532
1615
1676
1900
1639
1849
2027
1984
2095
1958
2199
1878
1949
VS
208
201
184
122
118
129
129
121
118
153
232
237
251
239
278
264
404
420
424
455
413
453
445
477
468
457
SS
2492
484<
317!
603
581
581
583
567
645
775
1055
1063
1140
1224
1330
1403
1582
1328
1441
1609
1658
1713
1601
1839
1559
1635
VSS
149
170
131
76
80
86
85
79
83
95
158
132
191
183
185
191
206
212
215
226
235
232
348
415
352
378
Metals
mg/1
Al
17.9
27.6
20.1
14.0
12.6
11.7
12.3
11.5
16.5
17 .6
18.5
18.6
18.2
17.5
19.2
20.4
21.0
22.1
22.2
23.7
25.6
24.1
25.4
26.7
25.0
26.5
Co
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10'
<.10
Cr
.13
.18
.13
.12
.13
<.10
<.10
<.10
.13
.16
.13
.14
.13
.16
.18
.15
.17
.15
.17
.18
.18
.20
.20
.21
.23
.22
Cu
<.10
.10
.10
<.10
<.10
<.10
<.10
<.10
<.10.
<.10
<.10
<.10
.10
<.10
.10
<.10
<.10
<.10
.11
.12
.11
.12
.14
.18
.15
.12
Mg
14.8
21.7
15.2
13.4
.12.6
13.4
12.6
12.6
13.7
13.8
14.1
16.2
13.6
13.8
13.2
15.3
14.8
16.0
17.0
19.2
16.1
20.0
16.4
19.0
16.9
18.6
Nl
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
Pb
1.11
1.08
1.04
.87
.75
.84
.76
.75
.86
.96
1.09
1.05
1.05
1.02
1.17
1.14
1.39
1.36
1.59
1.65
1.49
1.54
1.44
1.67
1.69
1.77
ALK
mg/1 as
CaCOj
74
74
74
66
62
74
62
pH
7.2
7.5
7.3
7.9
7.2
7.1
7.2
7.5
7.2
7.2
7.2
7.1
7.0
-------
Table 61. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 35
Date: 2/26/73
Time (hrs) From
Storm
Start
0.5
0.7
0.9
Last
Storm
290
290.2
290.4
Last
Peak
290
290.2
290.4
Q
CFS
32
58
71
Organics
mg/1
COD
227
234
406
TOC
84
92
120
BOD
100
80
120
Solids
mg/1
Total
1085
1086
1532
VS
255
261
335
SS
867
858
1361
VSS
129
147
133
Metals
mg/1
Al
7.3
7.6
13.4
Co
T.10
<.10
<.10
Cr
<.10
<.10
.11
Cu
<.10
<.10
.13
Ni
<.10
<.10
<.10
Pb
.65
.58
.85
ALK
mg/1 as
CaC03
74
72
76
pH
7.52
7.47
7.37
Table 62. TIME PARAMETERS AND ANALYTICAL RESULTS OF URBAN RUNOFF EVENT NUMBER 36
Date: 3/21/73
Time (hrs From
Storm
Start
.33
.50
.67
.84
1.01
1.18
1.35
1.52
1.69
1.86
1.03
1.20
1.37
1.54
1.71
1.88
Last
Storm
98
98.2
98.3
98.5
.2
.3
.7
.8
1.0
1.2
1.4
1.5
1.7
1.9
2.0
2.4
Last
Peak
98
98.2
98.3
98.5
98.7
98.8
99.2
99.4
99.5
99.7
99.9
100.0
100.2
100.4
100.6
100.9
Q
CFS
28
35
37
38
35
31
23
18
14
12
9
7
7
6
6
4
Organics
mg/1
COD
144
136
116
124
140
101
82
89
74
82
70
74
58
62
62
58
TOC
46
42
66
44
36
27
22
33
20
25
21
38
19
16
19
18
Nut
m
K-N
.4
.8
.6
.6
.3
.5
.4
.4
.4
.4
1.0
.4
.4
.4
.4
.4
rients
K/l
Total P
.92
.69
.73
.78
.70
.61
.58
.59
.48
.47
.48
.55
.46
.47
.52
.52
Fecal
Coliforms
/ml
450
400
350
350
350
300
300
300
250
180
170
160
140
140
140
150
Solids
mg/1
Total
684
603
652
1150
943
888
653
661
651
587
543
709
685
697
682
715
VS
230
198
183
225
209
144
178
169
184
144
144
137
153
193
188
146
ss
599
509
581
1256
894
799
510
611
495
505
431
655
574
685
525
652
VSS
130
114
96
102
148
119
85
105
96
89
91
98
85
98
103
99
Metals
mg/1
Al
7.2
6.6
7.4
9.6
9.6
9.1
7.6
7.9
6 7
7 ?
6 7
7.3
6.3
6 7
6.7
6.0
Co
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
< in
< in
<.10
-------
Table 63. THIRD FORK CREEK BASE FLOW OBSERVATIONS AT U.S.G.S. GAGE HOUSE
Date
11/1/71
11/8/71
11/12/71
11/16/71
11/19/71
11/20/71
12/2/71
12/13/71
12/14/71
12/16/71
12/16/71
12/21/71
1/5/72
1/19/72
1/26/72
2/9/72
3/15/72
3/23/72
3/30/72
4/19/72
4/26/72
6/8/72
7/11/72
7/26/72
8/21/72
9/13/72
10/12/72
11/2/72
11/10/72
1/25/73
3/1/73
3/20/73
MEAN
STD. DEV
Q
CFS
.8
1.7
1.2
1.2
1.3
1.2
.7
.6
.7
1.7
.9
.9
.9
.6
.7
c
C
.4
,7
i
t
t
.8
.8
.9
C
D.O.
mg/1
4.6
6.4
8.4
6.7
10.0
12.8
8.7
9.5
9,2
7.0
10.6
9.0
7.0
7.7
5.5
7.2
10.5
10.2
9.4
8.4
2.0
Temp.
'C
14
15
10.5
7.0
15
14
14
11
6
18.5
16
15
25
29
29
27
28
17
20.5
16
7.8
11
12.5
16.5
Orgariics
mg/1
COD
29
32
72
25
29
7
12
36
61
10
38
56
27
12
12
35
8
23
23
12
22
31
35
22
19
50
50
38
24
19
24
29
16
TOC
15
14
24
5
5
6
5
14
18
1
15
10
18
22
19
10
24
4
17
15
18
26
" 6
13
21
14
7
BOD
11
4
26
19
12
2
3
1
2
3
4
14
3
14
15
10
14
12
42
44
54
13
42
15
15
Nutrients
mg/1
K-N
5.0
5.6
9.0
5.5
2.7
3.6
1.4
1.7
1.6
4.7
4.6
6.2
1.2
2.9
2.9
.9
.5
.4
.4
.3
.3
.3
.5
.5
.4
.3
.5
.2
1.3
1.2
.4
2.2
2.3
Total-P
.6
.34
.63
.65
.97
.95
.45
.35
.64
.7
.7
.24
.8
.4
.02
.35
1.0
.22
.67
.27
.83
.69
1.1
.65
.98
.36
1.3
.35
.26
.25
.23
.57
.31
Fecal
tollform
*/ml
4
5
46
91
114
155
340
30
8
9
4
1
2
5
23
23
12
81
57
97
6
17
55
22
15
49
73
Solids
mg/1
Total
380
400
525
360
480
375
530
330
335
435
650
260
340
380
315
335
345
325
445
455
480
505
375
675
365
335
270
254
347
400
106
VS
55
60
40
95
75
70
70
155
40
75
145
105
105
137
103
116
90
36
SS
41
30
18
20
20
25
100
65
5
55
4
25
60
15
5
50
20
330
15
72
50
73
VSS
4
5
30
80
15
37
25
29
Metals
mg/1
Al
13.6
.7
.3
.3
3.7:
6,6(
Ca
12.5
26.0
34.4
31.1
42.1
28.0
33.2
4.5
26.5
12.3
Co
.44
.54
.44
.38
.4
.14
.24
.17
.03
.17
.21
.18
<.10
c.l
C.I
C.I
c.l
C.I
.26
.15
Cr
.23
.10
.26
.30
.24
.37
.25
.14
.22
.25
<.l
<.l
<.l
<.l
<.l
•c.l
<.l
.23
.07
Cu
.35
.86
.34
.79
.35
.33
.10
.11
.11
<.10
<.10
<.10
<.10
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
<.l
.27
.27
Fe
.7
2.5
1.4
1.1
2.2
1.8
1.2
1.9
1.3
.9
1.2
1.4
3.4
2.1
1.5
1.6
1.9
1.6
1.5
1.1
1.0
.8
.9
.9
1.5
.6
Mg
10.8
14.8
17.2
12.2
14.0
12.0
10.5
6.2
11.8
8.7
11.8
3.1
Mn
.55
.49
.87
;69
.53
.47
.42
.66
.68
.76
.36
.38
.39
.20
.74
.20
c.10
.52
.19
Ni
.16
.24
.21
.24
.13
.12
.12
<.10
<.10
<.10
<.10
.16
.05
Pb
.5
.3
.28
.29
.53
.45
.31
.39
.26
.15
.14
•c.10
<.10
<.10
<.10
<.10
•c.10
•c.10
•c.10
.11
.14
.14
.26
.14
Sr
.37
<.10
.37
0
Zn
•c.10
.18
.12
.14
<.10
.13
<.10
.17
.26
.16
<.10
.13
<.10
.06
.34
.24
.48
.12
.16
.11
ALK
mg/1 as
CaC03
150
124
136
124
149
119
137
86
122
142
104
93
112
122
19
pH
7.9
7.5
7.3
7.6
7.5
7.6
7.9
7.9
8.9
8.0
7.8
8.6
8.1
8.5
7.9
8.2
7.8
8.6
7.6
7.6
7.7
7.6
7.3
7.6
7.9
.4
-------
Table 64. SUB-BASIN E-l BASE FLOW OBSERVATIONS
00
Date
12/14/71
12/21/71
1/5/72
1/19/72
1/26/72
2/9/72
3/15/72
3/23/72
3/30/72
4/19/72
4/26/72
6/8/72
7/11/72
7/26/72
8/21/72
9/13/72
10/12/72
11/2/72
11/10/72
1/25/73
3/1/73
3/20/73
MEAN
STD.DEV.
D.O.
mg/1
10.6
10.2
8.7
8.3
7.8
7.8
7.4
5.7
6.2
8.4
8.2
8.4
11.8
11.3
11.2
8.8
1.9
Temp.
'C
6.0
13.5
12.0
12.0
18.5
19.5
22.0
21.0
18.0
14.5
16.0
12.5
6.5
10.0
10.5
Organics
mg/1
COD
20
60
20
15
12
8
8
23
12
12
6
66
36
19
23
16
23
23
12
19
16
21
15
TOC
12
12
21
15
13
8
10
10
10
31
26
12
50
12
19
15
21
18
20
15
14
10
17
9
BOD
2
10
1
2
<1
2
2
8
2
13
20
9
13
20
20
17
24
7
10
10
a
Nutrients
m /I
K-N
1.3
5.3
1.1
3.2
2.5
.7
.6
.5
.3
.4
.3
1.1
.9
.4
.6
.5
.4
.3
.5
.4
.3
1.02
1.22
Total-P
.05
.06
.10
.08
.02
.10
.07
.06
.06
<.05
.47
.16
<.05
.27
<.05
<.05
.05
.16
.07
.06
.10
.10
Fecal
Coliform
0/nl
10
53
1
4
2
10
1
1
2
10
5
54
3
4
5
1
1
2
.4
.3
1
8
15
Solids
me/1
Total
295
305
300
340
330
• 310
335
325
385
950
435
315
440
345
310
315
235
266
262
358
152
VS
60
65
45
90
85
85
165
185
40
100
140
110
90
92
126
8J
98
40
SS
5
40
4
15
580
20
25
40
8
82
187
vss
(,
5
40
8
14
17
Metals
Al
.78
.70
.65
.49
.66
.12
Ca
22.8
48.1
38.4
56.5
46.4
44.8
53.9
49.2
45.0
10.5
Co
<.10
.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
.10
0
Cr
.23
.27
.21
.27
.28
.29
<.10
•c.10
<.10
<.10
c.10
<.10
<.10
.25
.03
Cu
.10
.10
.11
•c.10
<.10
<.10
<.10
<.10
<.10
<.10
•c.10
<.10
.10
0
Fe
2.2
2.1
4.6
2.0
1.5
1.8
2.6
2.9
2.0
.8
1.7
5.3
1.0
1.6
2.3
1.3
Mg
9.9
16.4
14.4
13.2
14.6
12.2
20.5
9.2
16.2
7.6
13.4
3.9
Mn
.81
.56
.58
.68
.93
.95
1.05
.83
.92
2.69
3.96
.78
2.01
1.3
1.0
Nl
.15
.12
.30
<.10
<.10
c.10
<.10
.19
.09
Pb
.20
.33
.34
.30
.39
.39
.14
.28
<.10
<.10
•c.10
<.10
•c.10
<.10
•c.10
<.10
.23
.20
.27
.08
Sr
.29
.57
.43
.20
Zn
<.l
.11
•c.10
<.10
•c.10
<.10
•e.10
•c.10
•c.10
<.10
•e.10
.16
•c.10
<.10
•c.10
.13
.03
ALK
mg/1 as
CaCOj
190
170
224
244
249
177
262
186
188
154
102
85
128
181
55
pH
7.6
7.8
7.4
7.5
7.9
7-9
7.6
7.7
7.5
7.7
7.8
8.3
7.8
7.9
7.8
7.9
8.0
7.7
7.8
7.8
7.
7.8
7.7
.2
-------
Table 65. SUB-BASIN E-2 BASE FLOW OBSERVATIONS
Date
12/14/71
12/21/71
1/5/72
1/19/72
1/26/72
2/9/72
3/15/72
3/23/72
3/30/72
4/19/72
4/26/72
6/8/72
7/11/72
7/26/72
8/21/72
9/13/72
10/12/7
11/2/72
11/10/7
1/25/73
3/1/73
3/20/73
MEAN
STD.DEV
D.O.
mg/1
6.7
6.8
6.3
6.7
7.5
10.6
11.2
10.8
9.7
3.0
emp.
°C
5
17
13
14
24
24
23.0
25.0
24.5-
14.5
18.0
14.0
5.5
8.0
10.2
Organics
rag/1
COD
14
68
27
15
16
54
8
12
4
12
20
35
69
7
15
23
23
19
20
30
16
24
18
TOC
12
8
11
14
13
<1
18
12
30
28
22
8
18
5
6
12
15
2
11
13
18
13
8
DOD
2
8
2
4
<1
0.3
2
4
9
1
13
12
18
15
19
17
14
19
14
20
10
7
Nutrients
mg/1
K-N
.40
.15
.60
3.6
4.25
2.5
.4
.3
.2
.3
.3
.4
.3
.2
.3
.2
.2
.1
.2
.2
.2
1.05
L.55
Total-P
.26
.12
.13
.23
.25
.28
.33
.08
.19
.11
.06
.74
.27
.06
.16
.12
.18
.1
.1
.09
.18
.19
.14
Fecal
olif orm
#/ml
265
21
78
7
53
3
1
.2
3
6
80
34
2
1
1
9
0.5
1
.3
30
63
Solids
mg/
Total
340
340
415
415
415
380
380
370
435
465
465
340
315
430
325
395
416
397
406
392
44
VS
70
115
60
120
110
85
50
220
50
65
115
115
125
164
140
111
107
45
SS
5
60
10
2
5
40
10
20
20
35
20
21
18
vss
2
10
15
35
20
16
12
Metals
mg/1
Al
.25
1.30
.17
.39
.53
.5?.
Ca
18.1
48.7
41.2
44.2
46.9
48.3
28.8
84.1
45.0
19.1
Co
.18
.13
<.10
<-10
<.l
<.l
<.l
<.l
<.l
.15
.03
Cr
.23
.23
.20
.18
.26
.28
<.10
<.10
<.l
<.l
<.l
<.l
<.l
.21
.05
Cu
.11
.14
<.10
<.10
<.10
<.l
.25
<.l
<.l
<.l
<.l
<.l
.16
.07
Fe
1.2
1.6
3.9
1.3
1.7
2.0
2.2
1.6
.8
.7
.4
.4
1.0
1.0
1.4
.9
Mg
11.0
21.8
20.6
17.8
16.0
23.6
9.0
14.4
24.8
17.7
17.7
5.2
Mn
.79
.35
.28
.62
.83
.78
.45
.51
.63
.66
.36
.17
.12
.50
.23
Ni
.12
.18
<.10
<.10
<.10
<.10
.15
.04
Pb
.30
.33
.36
.33
.09
.16
.26
.29
<.10
<.10
<.10
<.10
<.10
<,10
<.10
<.10
<.10
.14
.19
.24
.09
Sr
.47
.23
.35
.17
Zn
.10
.10
.17
.10
.10
.15
.12
.12
.10
.10
MO
.27
.19
MO
MO
.15
.05
ALK
mg/1 as
CaCOj
172
156
168
98
157
149
153
196
85
170
166
140
182
153
31
pH
7.8
7.7
7.8
7.8
7. '9
9.0
7.8
8.0
8.2
7.8
8.1
7.7
8.0
7.9
7.9
7.8
7.8
7.8
7.9
7.9
7.9
7.9
.3
-------
Table 66. SUB-BASIN N-2 BASE FLOW OBSERVATIONS
Date
12/14/71
12/21/71
1/5/72
1/19/72
1/26/72
2/9/72
3/15/72
3/23/72
3/30/72
4/19/72
4/26/72
6/8/72
7/11/72
7/26/72
a/21/12
9/13/72
10/12/72
11/2/72
11/10/72
1/25/73
3/1/73
3/20/73
MEAN
STD.DEV.
D.O.
mg/1
3.6
5.4
4.6
4.5
5.8
6.7
9.3
5.1
7.5
3.2
Temp
°C
12.0
21.0
18.0
17.0
26.5
27.0
30.0
29.0
29.5
21.0
23.0
20.0
14.2
15.0
15.5
Organics
8/1
COD
68
176
38
88
16
31
50
19
35
19
47
14
84
26
549
50
115
72
44
69
99
81
114
TOC
24
16
14
23
32
23
21
21
13
41
24
20
20
22
10
178
20
30
24
22
26
19
29
34
BOD
21
42
2
26
3
15
4
13
2
18
7
24
85
13
62
27
26
26
73
25
24
Nut
m
K-N
4.8
.7
9.0
2.5
.9
.5
.8
.5
.2
.5
.2
.5
.5
.5
.6
.7
.5
1.6
1.6
.9
1.39
2.07
rients
R/l
Total P
.52
.61
.33
1.48
2.4
1.85
3.20
3.10
3.10
1.50
2.30
.10
1.8
1.2
2.2
1.5
2.6
2.7
1.5
2.6
.92
1.78
.94
Fecal
Colif orrn
(J/ml
220
87
21
2
16
1
3
2
4
3
110
1
3
4
4
3
140
140
12
240
51
78
Solids
Total
375
310
510
375
• 900
395
380
380
430
295
770
375
375
505
350
410
414
365
218
428
159
vs
40
95
55
120
95
85
75
165
25
105
130
135
135
139
131
99
102
39
SS
40
30
25
10
8
50
35
15
25
10
60
15
15
20
24
25
15
vss
10
8
5
15
10
60
15
15
20
24
18
16
Metals
mg/1
Al
.87
1.50
.74
.57
.92
.40
Ca
12.3
13.5
13.0
17.9
36.7
18.0
26.8
29.3
20.9
9.0
Co
.10
<.10
<.10
•c.10
<.10
<.10
<.10
<.10
<.10
.10
0
Cr
.37
.38
.25
.31
.32
.35
<.10
.18
.11
<.10
<.10
<.io
<.10
.30
.07
Cu
.14
<.10
<.10
<.10
<.10
<.10
<.10'
<.10
<.10
<.10
<.10
<.10
.14
0
Fe
1.4
1.9
2.2
1.9
1.2
1.7
1.4
1.6
1.4
.6
.9
.6
2.1
1.5
1.4
.5
Mg
16.5
13.4
12.8
7.0
17.0
10.4
12.3
6.3
9.2
7.2
11.2
3.8
Mn
.56
.52
.37
.69
.48
.52
.25
.27
.32
1.20
.18
.35
<.10
.47
.27
Hi
.14
.17
.22
<.10
<.10
<.10
<.10
.17
.04
Pb
.30
.30
.23
.30
.28
.12
<.10
<.10
.13
<.10
<.10
<.10
<.10
<.10
<.10
<.10
.15
.18
.15
.21
.07
Sr
.10
<.10
.10
0
Zn
.31
.23
.21
.19
.20
.65
.25
.52
.24
.23
.22
<.10
.34
2.70
.76
.51
.68
ALK
mg/1 as
CaCO
136
96
128
134
145
107
117
116
49
124
65
76
78
105
30
pH
7.4
7.5
7.1
7.3
8.1
7.7
9.2
9.0
8.6
9.2
7.2
8.3
8.2
8.0
7.8
8.0
8.2
7.4
7.6
7.4
7.3
7.3
7.9
.6
-------
Table 67. SUB-BASIN W-l BASE FLOW OBSERVATIONS
Date
12/14/71
12/21/71
1/5/72
1/19/72
1/26/72
2/9/72
3/15/72
3/23/72
3/30/72
4/19/72
4/26/72
6/8/72
7/11/72
7/26/72
8/21/72
9/13/72
10/12/72
11/2/72
11/16/72
1/25/73
3/1/73
3/20/73
MEAN
STD DEV.
D.O,
mg/-
6.1
6.8
7.6
6.8
8.3
11.0
11.0
10.4
8.8
1.8
Temp
°C
6.0
17.5
14
14
23
26.0
26.0
25.0
25.0
16.0
18.5
14.5
7.0
10.0
12.7
L7.0
Organlcs
rag/1
COD
28
36
20
8
12
4
4
4
12
19
35
25
27
108
19
19
15
15
16
15
12
22
22
TOC
14
10
16
14
12
1
17
10
8
28
28
9
20
8
21
16
8
12
21
22
12
15
7
BOD
2
2
3
4
<1
1
2
2
8
4
10
11
10
15
20
17
12
16
't
12
8
6
Nutrients
g/1
K-N
6.4
4.5
2.8
3.8
2.5
0.7
0.6
0.5
0.4
0.4
0.3
0.9
2.4
1.4
.8
.9
.5
.2
.4
.1
.2
1.46
1.68
Total-P
.42
.34
.47
1.48
.25
.06
.07
.06
.21
.18
.11
.36
.83
.62
.84
.52
.26
.06
.05
.06
.05
.34
.35
Fecal
Collform
///ml
35
70
102
15
2
2
2
4
34
150
140
480
420
650
120
10
1
2
25
119
188
Solids
mg/1
Total
275
195
260
265
240
245
260
270
280
300
235
240
240
275
220
250
240
223
228
250
25
VS
40
65
40
115
95
65
45
140
25
45
115
105
90
124
104
78
81
35
SS
15
10
4
10
5
105
10
25
10
40
5
2
20
29
VSS
4
5
10
10
40
5
2
11
13
Metals
n*/l
Al
.13
1.10
.18
.13
.38
.48
Ca
is.;
27. i
27.;
35. <
44.2
22.2
26. f
28.7
28.!
8.C
Co
.20
.15
.05
<.10
<.10
<.10
<.10
<.10
<.10
.13
.07
Cr
.30
.16
.22
.29
.27
.17
<.10
<.10
<.10
<.10
<.10
<.10
<.10
.23
.06
Cu
.11
.10
.14
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
.11
.02
Fe
1.2
1.8
1.3
1.9
1.5
1.6
1.7
1.5
1.2
.9
.9
.4
.4
.6
1.2
.5
Mg
9.4
14.4
16.0
8.2
13.6
16.0
9.9
5.6
12.5
9.8
11.4
3.7
Mn
.46
.51
.26
.83
.57
.59
.31
.19
.19
.69
.24
.25
<.10
.42
.21
Ni
.23
.22
.12
<.10
<.10
<.10
<.10
.19
.06
Pb
.50
.30
<.10
.20
.11
.13
<.10
<.10
.12
<.10
<.10
<.10
<.10
<.10
<.10
<.10
.17
.14
.13
.18
.12
Sr
.30
.20
.25
.07
Zn
<.10
<.10
<.10
<.10
«.10
<.10
<.10
<.10
<.10
<.10
^.10
<.10
<.10
<.10
<.10
ALK
mg/1 as
CaC03
124
116
126
132
122
113
128
106
113
106
90
84
102
112
15
Pi
7.',
7.i
7.7
7.(
7.<
1 .<-.
7.f
7.5
7.S
1.1
l.l
8.3
7.S
7.E
7.1
7.S
7.1
7.S
7.1
7.S
7.f
7.f
7.f
.]
-------
Table 68. SUB-BASIN W-2 BASE FLOW OBSERVATIONS
Date
12/14/71
12/21/71
1/5/72
1/19/72
1/26/72
2/9/72
3/15/72
3/23/72
3/30/72
4/19/72
i/76/72
6/8/72
7/11/72
7/26/72
8/21/72
9/13/72
10/12/72
11/2/72
11/10/72
1/25/73
3/1/73
3/20/73
MEAN
STD.DEV.
D.O.
mg/1
8.5
7.8
10.0
9.0
8.6
9.5
11.3
10.4
9.9
1.6
Temp.
°C
5.0
18.0
13.0
13.0
22.5
19.0
24.0
23.0
23.0
15.0
17.0
14.0
9.5
8.0
11.0
Organlcs
mg/1
COD
25
56
24
22
20
8
12
8
8
12
18
23
31
19
12
12
15
19
202
19
16
28
41
TOC
16
16
24
14
16
1
16
11
10
20
22
8
32
4
15
15
13
36
20
40
14
12
17
9
BOD
2
1
5
<1
0.5
2
2
8
1
14
8
8
13
8
17
1Z
138
22
78
18
34
Nutrients
mg/1
K-N
8.4
LO.O
17. 0
3.5
4.0
1.0
.5
1.3
.40
.4
.3
.3
.3
.2
.3
.2
.3
3
.3
.4
2.6
4.4
Total-P
.85
.85
2.40
.59
.42
.06
.20
.08
.10
.08
.06
.09
.07
.'10
.05
.05
.05
8
.14
.05
.71
1.80
Fecal
CoHform
f?/ml
380
805
95
3
4
5
11
1
0.5
2
6
13
4
24
9
3
.6
3
1
72
198
Solids
mg/1
Total
260
285
280
280
365
260
255
285
395
330
290
245
200
310
240
275
376
290
269
289
49
VS
45
65
50
100
90
60
45
150
25
35
100
95
105
190
123
83
85
44
SS
5
90
10
5
4
10
45
20
20
10
25
51
14
24
25
vss
5
4
5
10
25
51
14
16
17
Metals
mg/1
Al
.3
1.8
.19
.24
.63
.78
Ca
12.3
27.6
31.8
35.2
32.2
24.2
36.6
43.7
30.4
9.4
Co
<.10
.17
.18
t.10
c.10
<.10
t.10
c.10
c.10
.18
0
Cr
.34
.37
.23
.26
.30
.21
<.10
<.10
<.10
.14
<.10
<.10
<.10
.26
.07
Cu
.11
.11
<.10
<.10
<.10
<.10
<.10
<.10
.22
<.10
<.10
<.10
.14
.06
Fe
2.2
7.2
3.4
2.3
0.8
1.9
2.6
2.0
1.5
2.7
.4
.8
.5
.7
2.8
2.9
Mg
9.5
13.7
14.4
10.4
12.2
12.6
11.1
7.8
26.0
6.6
12.4
5.4
Mn
.71
.59
.46
.49
.65
.58
.11
.28
.13
.28
.19
<.10
<.10
.40
.21
Hi
.16
.25
.20
<.10
<.10
<.10
<.10
.20
.04
Pb
.30
.28
.10
.31
.20
.10
.23
.31
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
.13
<.10
.16
.19
.08
Sr
.27
.16
.22
.08
Zn
<.10
.12
.13
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
.11
.01
ALK
mg/1 as
CaC03
114
126
156
156
163
140
104
142
130
120
114
124
150
134
19
pH
7.6
7.5
7.1
7.4
7.6
7.8
8.5
7.9
8.5
8.9
7.7
8.0
8.2
8.1
8.0
7.9
7.5
8.1
7.8
7.1
7.5
7.6
7.9
.5
-------
Table 69. ANALYTICAL RESULTS OF URBAN RUNOFF FROM SUB-BASIN E-l
Stom
No.
19
1
4-
20
25
29
33
MZAN
Q
CFS
0.034
0.034
0.027
.26
.03
.46
.7.2
.30
.12
.06
.12
1.0
.85
2.30
1.60
2.80
.85
.26
5.4
2.8
0.89
2.81
2.81
3.39
.38
.26
.72
1.38
1.38
.72
.46
Sample
Time
Military
1555
1620
1646
1417
0405
0520
0650
0720
0805
0835
0935
1035
1434
1454
1512
1528
1543
1628
0815
0845
0905
0922
0945
1000
1030
1445
1500
1515
1530
1545
1600
1630
Organics
rng/l
COD
67
49
33
24
138
86
106
170
102
54
54
88
78
97
144
54
89
50
70
237
112
244
66
66
66
61
57
72
146
134
111
65
93
TOC
19
15
12
40
48
26
29
49
46
22
14
31
31
36
18
17
22
18
27
64
21
95
38
14
16
26
44
38
44
34
30
BOD
15
12
11
58
50
48
48
50
44
130
140
120
120
100
110
120
22
32
30
34
36
38
32
60
Nutrients
mg/1
K-N
.8
.6
.5
.4
.9
.8
.5
.5
.6
.3
.2
.2
.2
.2
.3
.3
.3
.3
.3
.4
.3
.3
.2
.2
.2
.2
.2
.2
.3
.36
Total-P
.44
.29
.18
.14
.69
.14
.56
.85
.22
.52
.44
.61
.40
.50
.45
.27
1.30
.72
1.20
.66
.58
.59
.38
.35
.39
.66
.70
.64
.50
.50
Fecal
Coliform
///ml
800
750
500
470
1200
960
2200
870
330
220
37
40
42
81
110
380
240
540
Solids
mR/1
Total
405
320
265
395
355
615
300
1220
750
1790
600
770
470
330
2970
1200
3095
1020
645
820
389
361
425
908
997
722
394
834
VS
75
65
60
170
145
185
95
210
200
300
180
170
160
235
315
150
315
130
115
120
299
295
306
321
323
290
241
202
SS
275
165
80
115
320
90
285
865
580
235
170
195
1100
600
1700
460
590
260
180
2855
1040
2925
945
550
715
145
120
194
792
825
503
203
627
VSS
55
45
30
20
55
20
45
135
75
25
15
20
180
130
210
120
130
100
20
235
65
230
65
30
50
132
145
151
144
247
221
139
102
Metals
mg/
Al
5.6
38.9
17.8
75.0
14.8
20.7
15.8
26.9
Ca
1.0
3.0
1.1
1.1
2.1
2.3
6.5
1.6
1.2
5.0
1.2
1.6
1.0
2.2
Co
<.10
.10
.10
.10
.10
.10
.10
.10
.10
.10
<.10
<.10
<.10
Cr
<.10
.11
.13
<.10
<.10
<.10
<.10
.15
<.10
.33
<.10
<.10
.15
*.13
Cu
<.10
<.10
<.10
•C.10
<.10
<.10
<.10
.13
<.10
.23
<.10
<.10
<.10
<.10
<.10
<.10
.10
.10
.13
<.10
*.ll
Fe
10.6
4.8
3.1
9.9
17.1
1.8
17.3
25.8
20.0
5.5
3.9
4.5
10.3
Mg
5.0
6.0
7.2
4.2
4.2
3.4
5.1
14.9
6.2
61.5
7.2
10.2
7.6
15.9
Mn
.81
.60
.37
2.71
.79
.33
.65
2.58
.51
.29
.25
.21
.36
.38
.27
.62
.52
.35
.29
.84
Ni
<.10
<.10
<.10
<.10
<,10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
Pb
.53
.29
.10
.11
.34
.10
.25
.68
.30
.17
.13
.19
*.26
Sr
<.10
<.10
<.10
<.10
.10
.10
.10
<.10
Zn
.31
.34
.42
.19
.19
.14
.15
.11
.15
.27
.24
.19
.17
.22
ALK
mg/1 as
CaCOj
58
50
32
13
21
31
16
44
30
28
32
pH
7.1
7.0
7.1
6.9
7.3
6.4
6.5
6.8
7.2
6.8
6.9
6.7
6.9
6.6
6.8
6.9
* Observations less than detectable limit are Included in mean as equal to limit.
-------
Table 70. ANALYTICAL RESULTS OF URBAN RUNOFF FROM SUB-BASIN E-2
S torn
N^.
o .
19
I
j
20
25
29
33
'
MEAN
ppc
\j t O
20
17
8.8
]4
18
30
35
44
28
18
20
45
4.6
45
45
67
14
13
207
109
146
127
127
109
28
25
32
44
44
44
32
Sample
Time
Military
1605
1627
1654
0335
0525
0700
0730
0810
0839
0750
1045
1443
1500
1518
1537
1555
1633
0825
0850
0910
0930
0950
1005
1035
1450
1505
1520
1535
1550
1605
1635
Organ ics
mg/1
COD
50
59
53
238
142
260
464
204
61
40
63
136
51
120
106
85
35
82
198
116
155
89
116
89
100
108
180
242
169
127
115
130
TOC
10
10
13
48
63
40
41
13
14
23
26
37
35
45
62
32
38
28
32
BOD
9
9
8
46
44
52
50
54
52
130
130
130
130
110
140
130
34
42
96
94
38
42
34
69
Nutrients
mg/1
K-N
.8
.7
.7
2.4
1.2
1.0
.8
.6
.1
.2
.2
.2
.2
.3
.3
.2
.2
.2
.2
.2
.2
.2
.3
.2
.2
.2
.2
.3
.44
Total-P
.32
.26
.22
.32
.30
.51
.97
.24
.58
.46
.53
.48
.44
.32
.17
1.40
.77
.85
.70
.48
.66
.39
.36
.54
.79
.85
.64
.49
.53
Fecal
Coliform
II /mi
160
83
80
64
520
460
100
350
710
64
43
130
92
95
71
67
63
185
Solids
mg/1
Total
260
215
195
445
365
575
205
1090
750
1050
1020
710
290
140
3190
1450
1960
1390
790
1510
558
546
662
1153
1009
774
641
849
vs
55
40
45
205
170
195
85
150
90
120
90
80
70
330
180
190
230
110
150
265
160
191
235
241
181
205
156
SS
150
130
75
70
65
145
455
500
200
110
125
1000
630
920
950
630
130
30
3100
1290
1780
1370
7^0
1541
340
300
397
922
778
530
359
638
vss
50
45
35
20
5
50
145
135
30
20
20
80
50
50
40
310
120
110
80
40
70
159
70
92
136
123
83
81
80
Metals
mg/1
Al
1.6
43.7
23.8
29.2
22.8
15.7
21.6
22.6
Ca
1.6
2.2
2.5
1.8
1.9
4.4
27.3
2.5
2.0
2.3
1.3
2.0
1.5
4.1
Co
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
.10
Cr
.12
.12
.14
.17
<.10
<.10
c.10
.34
.11
.27
.15
.17
<.10
.15
Cu
.12
<.10
<.10
<.10
.11
<.10
<.10
.21
.15
.14
<.10
<.10
.11
.16
.16
.17
.15
.16
.15
.13
.13'
Fe
4.4
3.4
2.8
.7
.7
2.4
13.4
21.6
4.8
5.2
3.7
5.7
Mg
6.4
4.4
7.0
6.2
5.4
4.0
8.8
24.0
12.9
23.5
9.5
15.4
10.9
ID. 6
Mn
.42
.19
1.28
.55
.28
.47
1.07
.63
.23
.14
.17
.41
.43
.61
.81
.60
.61
.47
.49
Nl
<.10
.10
.10
.10
.10
.10
.10
.10
.10
.10
.10
«.10
Pb
.10
.10
.26
.36
.15
.68
1.59
.88
.38
.18
.33
.13
Sr
.10
.10
.10
.10
.10
.10
.10
<.10
Zn
.45
.27
.35
.33
.28
.14
.34
.30
.33
.45
.39
.32
.33
.32
ALK
mg/1 as
CaC03
40
46
45
20
24
52
17
44
40
32
36
pH
7.0
7.2
7.0
7.0
6.7
7.0
6.8
6.9
6.7
7.1
7.2
7.2
7.1
6.9
6.6
6.8
6.9
* Observations less than the detectable limit are included in the mean as equal to the limit.
Ul
-P-
-------
Table 71. ANALYTICAL RESULTS OF URBAN RUNOFF FROM SUB-BASIN N-2
-orn
1«
lO .
19
1
i
20
:5
9
3
IAN
Q
rrc
\*t j
8.5
.38
.38
1.8
1.8
10.1
17
7.1
1.8
1.6
3.1
18
18
29
18
23
6.1
4.0
J.05.0
14.0
84.0
52
44
44
4.0
2.9
6.1
15
14
14
4
Sample
Time
Military
1605
1627
1655
0335
0525
0700
0730
0810
0840
0950
in/,s
1443
1500
1518
1537
1555
1633
0825
0850
0910
0930
0950
1005
1040
1450
1505
1520
1535
1550
1605
1635
Organics
mg/1
COD
50
48
42
184
137
180
498
137
72
59
124
82
50
132
97
66
112
123
146
50
104
42
46
38
69
69
54
115
96
58
108
102
TOC
16
15
15
82
61
53
130
20
26
20
28
35
22
66
21
32
12
50
28
20
14
10
14
10
25
18
16
18
30
30
16
30
BOD
3
3
2
56
52
56
52
52
50
220
210
200
180
190
190
180
34
34
36
38
14
28
32
83
Nutrients
mg/1
K-N
2.6
2.4
2.5
1.5
.8
.8
.4
.8
.1
.2
.1
.1
.1
.3
.6
.2
.2
.2
.1
.2
.2
.2
.3
.2
.2
.2
.2
.2
.57
Total-P
.99
.87
.84
.61
.52
.84
.63
.36
.50
.30
1.00
.42
.51
.41
.76
.96
.44
.90
.46
.44
.46
.39
.45
.42
.71
.67
.50
.42
.59
Fecal
Coliform
///ml
14
23
32
17
10
180
200
160
100
21
9
12
14
15
18
28
13
50
Solids
mg/1
Total
210
200
235
375
895
395
160
1590
830
5080
1160
1360
380
790
2350
800
2480
910
910
970
455
485
420
841
1010
605
484
977
VS
60
55
55
145
150
95
60
220
180
490
50
10
90
140
60
160
30
20
10
196
215
212
237
265
97
167
133
SS
45
35
25
25
135
350
1530
315
100
35
145
1370
600
5180
1090
1300
340
470
2610
760
2550
870
89
870
249
282
225
610
848
538
307
770
VSS
20
5
5
25
55
110
250
55
60
30
65
110
70
470
80
120
30
20
170
40
180
50
70
40
132
110
115
152
191
146
114
99
Metals
mg/1
Al
12.1
37.3
15.7
36.7
17.7
16.9
17.4
21.9
Ca
1.1
1.2
1.4
1.3
.9
1.8
5.4
1.6
1.0
1.8
1.1
.9
.7
1.6
Co
.10
.10
.10
.10
.10
.10
.10
.10
.10
.10
.10
<.10
Cr
.14
.19
.31
.16
.13
.14
<.10
.17
<.10
.22
0.18
.18
<.10
*.16
Cu
.12
<.10
.13
<.10
<.10
<.10
.15
.13
<.10
<.10
<.10
<.10
<.10
.12
.11
.13
.17
.13
.15
.15
*.12
Fe
1.2
.8
.7
1.4
2.2
5.7
29.0
5.5
2.6
1.0
3.2
4.8
Mg
8.2
4.4
14.7
6.4
6.6
3.4
10.2
18.6
8.1
17.5
10.2
10,2
9.7
9.9
Mn
.16
.17
.15
.48
.32
.54
.64
2.25
.29
.22
.34
.34
.26
.46
.64
.77
.68
.52
.51
Ni
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
Pb
<.10
<.10
<.10
.10
.14
.26
1.25
.54
.58
<.10
.31
*.32
Sr
.10
.10
.10
.10
.10
.10
.10
<.10
Zn
.30
.19
.47
.26
.19
.12
.26
.28
.25
.38
.34
.28
.22
.27
ALK
mg/1 as
CaC03
30
38
64
21
16
14
41
13
40
46
24
32
pH
7.0
7.0
6.8
6.9
6.6
6.8
6.4
6.4
6.7
7.2
6.9
7.0
6.9
6.9
7.0
6.6
6.8
Observations less tlian detectable limit are Included in the mean as equal to the limit.
t-n
Ul
-------
Table 72. ANALYTICAL RESULTS OF URBAN RUNOFF FROM SUB-BASIN W-l
torn
No .
19
[
20
25
29
33
-AN
In
v
CFS
5.5
3.8
1.8
3.8
1.2
3.8
•29
23
6.0
2.4
3.8
38
138
124
75
32
32
101
167
188
45
35
20
51
341
167
167
209
190
297
9
51
11
16
15
14
Sample
Time
Military
1617
1637
1710
0400
0540
0710
0745
0823
0855
1005
1100
1425
1440
1450
1455
1510
1525
1540
1555
1610
1625
1640
1655
0335
0900
0920
0940
1000
1020
1050
1445
1515
1545
1615
1645
1715
Organ ics
mg/1
COD
55
43
35
230
87
176
133
80
74
49
43
124
82
70
85
91
87
87
139
194
170
127
119
58
74
132
109
116
101
74
42
46
146
54
54
42
95
TOC
24
22
18
60
50
52
48
26
30
16
17
65
32
22
31
35
27
24
42
26
63
56
48
38
34
40
41
23
26
42
58
12
16
34
35
BOD
11
10
10
52
46
48
50
48
52
44
46
52
50
50
52
150
130
140
140
120
120
140
68
20
42
28
18
22
36
Nutrients
mg/1
K-N
.4
.4
.4
1.0
.5
.5
.4
.4
.2
.2
.2
.2
.2
.2
.2
.2
.2
.3
.3
.3
.3
.3
.2
.3
.3
.3
.3
.3
.3
3.6
.3
.3
.3
.42
Total-P
.33
.22
.19
.64
.12
.49
.52
.27
.48
.31
.37
.48
.49
.57
.44
.76
1.10
.80
.78
.62
.32
.42
.83
.79
.82
.76
.58
.26
.32
1.70
.35
.42
.39
.54
Fecal
Coliform
it/ml
300
250
280
590
70
330
290
510
480
550
31
32
27
27
61
58
242
Solids
mg/1
Total
440
320
275
455
520
445
295
800
450
650
850
910
1340
840
1690
2810
1680
1310
1200
430
460
1790
1030
1350
1140
850
234
279
361
295
373
322
819
vs
70
65
45
195
185
120
105
70
50
50
170
140
200
140
190
280
100
90
200
100
70
180
120
70
130
110
119
168
234
130
146
187
132
ss
270
155
85
160
35
330
310
295
350
110
95
740
340
530
760
750
1150
710
1720
2670
1820
1400
940
280
350
1680
920
1330
1050
700
25
64
106
113
169
131
629
vss
55
25
20
70
30
95
85
6(1
75
53
30
140
30
20
160
90
150
40
160
210
190
210
60
40
60
140
50
90
120
30
6
52
74
58
151
152
87
Metals
mg/1
Al
6.8
9.9
27.1
18.6
22.8
24.4
14.2
17.7
Ca
2.5
2.4
2.6
1.2
1.6
1.6
1.1
1.7
1.4
2.1
1.9
2.5
4.8
1.9
1.7
1.2
1.0
1.0
.9
1.8
Co
.10
.10
.10
.10
.10
.10
.10
.10
.10
.10
.10
<.10
Cr
.10
<.10
<.10
<.10
<.10
.13
.11
.14
.14
.12
.38
<.10
.10
<.10
.17
<.10
.17
<.10
.11
*.13
Cu
<.10
<.10
.10
<.10
<.10
<.10
.11
<.10
<.lO
<.10
.12
.11
<.10
<.10
.11
<.10
<.10
..10
<.10
<.10
<.10
<.10
<.10
.11
<.10
*.10
Fe
8.8
4.9
3.3
9.6
1.1
17.1
14.5
17.0
18.2
5.0
3.1
9.5
Mg
5.4
5.0
4.6
6.0
5.8
7.6
4.0
6.4
9.2
7.2
7.0
7.2
8.0
6.4
13.2
9.4
12.2
9.5
7.5
7.5
Mn
.97
3.67
2.02
.9
.16
1.01
1.05
.96
.79
.30
.17
.21
.21
.11
.32
.17
.21
1.09
HI
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
<.10
Pb
<.10
<.10
<.10
.43
.11
.66
.48
.44
.22
<.10
.19
*.27
Sr
<.10
<.10
<.10
<.10
<.10
<.10
<.10
Zn
.15
<.10
.16
.19
.21
.27
.24
.29
.45
.35
.32
.25
.12
.13
.19
.13
.16
.11
*.32
ALK
mg/1 as
CaC03
56
60
116
26
29
21
18
51
15
42
28
32
41
PH
7.4
7.3
7.3
6.7
6.9
7.1
6.7
6.8
6.9
7.0
6.6
6.5
7.4
6.8
6.8
6.8
7.1
6.9
7.0
7.0
* Observations less than detectable limit are Included In the mean as equal to the limit.
-------
Table 73. ANALYTICAL RESULTS OF URBAN RUNOFF FROM SUB-BASIN W-2
ono
,,
o«
L9
•
;
0
5
9
3
IEAN
pvc
\JfJ
.49
.54
.24
.62
.20
1.9
5.0
3.3
1.4
.62
.54
4.2
3.8
3.3
31
22
5.2
6.5
24
15
25
25
19
25
1.5
1.3
2.3
3.3
3.3
3.3
2.3
Sample
Time
Military
1610
1632
1700
0350
0530
0705
0738
0818
0847
1000
1050
1447
1505
1523
1542
1558
1633
0830
0855
0915
0935
0955
1015
1045
1455
1510
1525
1540
1555
1610
1640
Organics
mg/1
COD
73
40
33
74
94
110
139
118
72
59
35
210
116
82
175
178
105
210
279
159
116
180
100
81
35
27
58
42
42
58
46
101
TOG
17
14
15
31
41
40
34
38
30
21
30
54
43
27
57
16
60
22
78
52
38
48
24
22
22
16
19
18
18
34
16
32
BOD
9
9
9
48
48
40
54
52
50
190
200
200
200
190
200
210
16
14
28
26
26
26
26
81
Nutrients
n.R/1
K-N
.4
.4
.4
.5
.6
.4
.4
.4
.2
.2
.2
.2
.2
.3
.4
.3
.3
.2
.3
.3
.3
.3
.3
.3
.3
.2
.3
.3
.31
Total-P
.29
.25
.15
.38
.35
.59
.80
.26
.91
.41
.38
.96
.65
.52
.4
1.7
1.1
.8
1.1
.61
.69
.30
.28
.38
.36
.52
.59
.49
.57
Fecal
Colifonn
It /mi
310
280
270
800
240
910
1000
170
120
20
31
35
41
50
84
95
54
265
Solids
mg/1
Total
285
265
240
320
560
615
225
2160
820
860
3930
1660
760
890
2930
1480
1490
1630
800
940
274
268
385
360
413
413
363
938
VS
50
50
40
110
150
105
55
150
30
160
410
260
160
10
240
120
100
90
70
158
118
149
146
208
181
178
134
SS
135
110
60
35 .
55
345
705
530
265
115
45
2175
800
660
3810
1640
610
790
2870
1760
1380
1670
740
890
35
18
155
96
157
159
106
739
VSS
25
25
15
35
40
95
140
95
95
55
35
250
100
260
500
350
280
40
290
410
140
150
40
40
147
128
139
89
113
150
138
142
Metals
mg/1
Al
13.5
42.2
28.0
23.0
24.1
13.6
16.4
22.9
Ca
2.5
2.9
2.1
1.3
1.5
3.1
3.9
2.5
1.4
1.0
1.3
1.3
1.3
2.0
Co
.10
.10
.10
.10
.10
.io
.10
.10
.10
.10
.10
<.10
Cr
.32
<.10
.10
.19
.11
.12
.13
.34
.28
.19
.12
<.10
.22
<.10
.10
<.10
<.10
<.10
.13
<.10
*.15
Cu
.11
<.10
<.10
.16
.16
<.10
<.10
.15
.16
.11
.15
<.10
.12
*.12
Fe
4.4
4.2
2.9
8.8
11.9
29.6
27.4
23.8
20.2
5.4
2.7
12.8
Mg
14.1
5.8
5.8
11.4
7.0
4.8
10.4
21.8
16.0
11.3
10.9
5.8
1.4 .3
L0.7
Mil
.19
.18
1.21
.77
.95
1.24
1.26
.86
.50
.23
.11
.22
.19
.31
.22
.30
.31
.34
.52
Ni
.10
.10
.10
.10
.10
.10
.10
.10
.10
.10
<.10
<.10
Pb
<.10
<.10
<.10
<.10
.28
.61
.40
.45
.16
.25
.19
*.25
Sr
.12
.14
.10
<.10
<.10
.10
<.10
*.ll
Zn
.57
.22
.18
.41
.43
.20
.15
.12
.13
.16
.17
.18
.14
.23
ALK
mg/1 as
CaC03
54
64
54
40
51
22
51
18
46
40
38
43
pH
7.2
7.4
7.2
7.1
7.0
7.3
7.3
7.1
6.9
7.3
6.8
6.9
6.9
7.1
7.0
7.1
7.1
Ul
* Observations less than detectable limit are Included In mean as equal to the limit.
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-670/2-74-096
3. RECIPIENT'S ACCESSI ON-NO.
4. TITLE AND SUBTITLE
CHARACTERIZATION AND TREATMENT OP URBAN LAND RUNOFF
5. REPORT DATE
December 1974; Issuing Date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Newton V. Colston, Jr.
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORG "\N IZATI ON NAME AND ADDRESS
University of North Carolina Water Resources Research.
Institute
124 Riddick Building, North Carolina State University
Raleigh, North Carolina 27607
10. PROGRAM ELEMENT NO.
1BB034/ROAP:21-ATB/TASK:014
11. CONTRACT/GRAN!
11030 HJP
NO.
12. SPONSORING AGENCY NAME AND ADDRESS
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final - 7/71 to 9/73
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Urban land runoff from a 1.67 square-mile urban watershed in Durham, North
Carolina, was characterized with respect to annual pollutant yield. Regression
equations were developed to relate pollutant strength to hydrograph characteristics.
Urban land runoff was found to be a significant source of pollution when compared to
the raw municipal waste generated within the study area. On an annual basis, the
urban runoff yield of COD was equal to 91 percent of the raw sewage yield, the BOD
yield was equal to 67 percent, and the urban runoff suspended solids yield was 20
times that contained in raw municipal wastes for the same area. Downstream water
quality was judged to be controlled by urban land runoff 20 percent of the time.
In urban drainage basins, investments in upgrading secondary municipal waste
treatment plants without concomitant steps to moderate the adverse effects of urban
land runoff are questionable in view of the apparent relative impact of urban land
runoff on receiving water quality.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COS AT I Field/Group
*Runoff, ^Surface drainage, *Water
pollution, Flocculants, Waste treatment,
*Water quality, Coagulation, Computers
iVUrban runoff, *Storm
runoff, *Urban drainage,
*Stormflow, *Water
pollution sources,
*Stormwater characteri-
zation, Storm water
management model
13B
3. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)'
UNCLASSIFIED
21. NO. OF PAGES
170
EPA Form 2220-1 (9-73)
CURITY CLASS (This pagej
UNCLASSIFIED
22. PRICE
158
U.S. GOVERNMENT PRINTING OFFICE: 1975-657-591/53'.3 Region No. 5-|l
------- |