10.

11.

12.

13.

14.

15.

16.

17.

18.

DDD - an organochlorine insecticide [1,1-dichloro-2, 2-bis-{p-

chlorophenyl) ethane].

DDT - an organochlorine insecticide closely related to DDD [1,1,1,-
trichloro-2, 2-bis-(p-chlorophenyl) ethane].

Dieldrin - an organochlorine insecticide of fairly complex molecu-

lar structure,

Dissolved Oxygen (DO) - the amount of oxygen dissolved in a liquid.
If at equilibrium with the overlaying atmosphere, it is then con-
sidered saturated, Must be present to support aerobic aquatic life,

Is consumed naturally in the "self-purifyingTM” process of waterways.

Endrin - an organochlorine insecticide which has the same struc~

tural formula as dieldrin and is its isomer.

Equivalent Days of Accumulation (EDA) - a measure of the relative

days of accumulation of pollutants on a street surface as a function

of rainfall and sweeping history and respective removal efficiencies.

Fecal Coliforms (FColi) - indicators of recent fecal pollution in
water supplies by pathogenic bacteria, expressed as number of

organisms per gram of solids of street surface material.

Iron (Fe) - an element that imparts a bitter taste to water and a

brownish color to clothing laundered in such water,

Lead (Pb) - a highly toxic heavy metal when ingested for either
brief or prolonged periods (cumulative poison).

‘Lindane - an organochlorine insecticide which is the gamma isomer

of benzene hexachloride.


1143 Ft, >

ILLLLL ALLL

ANAANRAAANRARN

LLLLLLL MA

CLLLLLLL LALLA

\)
N
N
N
N
N
N

WAAAAANRRAARQAAARAAARRARAARARANRANRRANAN

AANANAANRAAS

LLLLLLLLLLA

NA SS ARAARRNRANNS

LLLLLLLLLLAAALLLLLLLLLLA

1143 Ft.

N

Y Street Area = 10 Acres
V4

Figure 12c, Street Surface Network

1-43


e distribution of handbills

e posting of notices and political posters
® street vending

@ garden refuse

@ scavengers

e weed control

e dead animals

@ produce markets

e direct discharges into storm sewers

Typical and model antilitter ordinances published by Keep Americai'
Beautiful, Inc, and by AWPA in its book "Street Cleaning Practices” may
be used as check lists to determine the adequacy of existing local or-

dinances and to establish new litter control ordinances.

The effectiveness of local ordinances will depend on the enforcement.
Enforcement can often best be accomplished through municipal interde-
partmental cooperation, For example, the police department could en-
force ordinances pertaining to littering from moving vehicles, illegal
dumping of refuse, the storage of construction materials on sidewalks
and streets, etc. The fire department could enforce regulations per-
taining to storage of refuse which might create a fire hazard. The
health department could be concerned with the handling and storage of
refuse by food-handling establishments, Other city departments could
enforce regulations related to their functions, Enforcement by these

agencies should include both inspections and summonses.

An important aspect of litter ordinances and regulations is to establish
the responsibility for each source of litter, In many circumstances it
is impossible or impracticable to catch persons who actually do the

littering, but more responsibility could be placed on the owner of the

Iv-4


This relationship assumes that material began to accumulate on
a surface thoroughly cleaned by the last rain and that a single
sweeping operation was performed between rainfalls, Rainfalls
and more than one sweeping operation occurring since the last
substantial rain are not considered, but can be introduced by
multiple iterative process using appropriate rainfall removal
efficiencies and sweeping efficiencies, As previously indica-
ted, a total rainfall of 0,5 inches will remove 90 percent of
road surface particulates. Correspondingly, total rainfalls

of .27, .15, .08, and .02 inches will remove 70, 50, 30, and

10 percent, respectively. The efficiency of sweeping prac-
tices can vary substantially by sweeper type, operational param-
eters and street surface particulate parameters (such as wetness
and size distribution). In prior studies, URS has measured
street sweeper/flusher efficiencies in a range from 11 to 62 per-

cent removal, An average value of 40 percent is representative.

In evaluating the impacts of an assumed or hypothetical condi-
tion, it is best to ignore the rainfall effects and only use

the average street sweeping frequency. This procedure can also
be helpful in evaluating the effects of modifying the sweeping
programs of an area (see Section IV, part C.1.), if sufficient

operation parameter-effectiveness data is available.

Convert the solids load in 1b/curb mi to 1b/acre of street surface

as follows:

1b _ ( lb ) x curb mi )
acre of street surface — curb mi acre of street surface

Equivalent curb miles per acre of street surface are shown in
Table 2, arranged by land use types, However, if actual values

are known, it is best to use known values,


and public works practices. The overall weighted average loading intensity
for all samples was computed to be approximately 1400 1b/curb mile, In
general, industrial areas contained substantially heavier than average
loadings, while commercial areas were considerably below the average.
Industrial areas averaged 2800 1b/curb mile; commercial areas averaged

290 lb/curb mile, Average loading intensities for residential areas were
1200 1b/curb mile, but loadings varied widely from site to site, There

was a general tendency for newer, more affluent neighborhoods to be cleaner,
Asphalt streets were found to have loadings 80 percent heavier than con-
crete streets. Streets considered in poor to fair condition had loadings

about 2-1/2 times greater than streets in good to excellent condition.

A pattern in loading intensities across a typical street was also revealed.
Typically, 78 percent of the material was found within 6 inches of the curb

and over 95 percent occurred within the first 40 inches.

It was also determined that the rate at which rainfall washes loose partic-
ulate matter from street surfaces depends on three primary factors: rainfall

intensity, street surface characteristics, and particle size.

As a result of the findings in the above EPA study, an additional EPA study!”
was performed by URS Research Company to further define the character and

distribution of heavy metals contained in city street debris.

This project defined the breakdown of the particulates' compositions by
having mass spectrographic analyses performed on various samples. Using
these results, the heavy metals which were determined to have the greatest
water pollution potential (As, Cd, Cr, Cu, Fe, Pb, Mn, Hg, Ni, Sr, Ti, Zn
and Zr) were analyzed in each of about 75 samples collected nationwide in

10 cities in the previous study.

Other analyses conducted included: size affinities of the metals, solubili-

ties and toxicities of the road surface runoff mixture, and certain organic

y-10


A detailed and comprehensive study by AVCO Corporation? was conducted during
the fall of 1968 to determine the magnitude of stormwater pollution from
urban land areas in Tulsa, Oklahoma. Stormwater samples from selected test
areas were collected and analyzed for the usual pollution parameters, As a
result of these tests, statistical analytical procedures were developed to

relate runoff pollution to land-use variables,

The major sources of pollutants were considered to be material deposited on
impervious surfaces (street litter) and material eroded or picked up from
drainage channels. The largest amounts of pollutants were generated during

the season of greatest runoff.

The land surface characteristics which showed the highest correlation with
stormwater pollutant concentrations were (1) environmental conditions,
(2) geomorphic characteristics that affect drainage, and (3) the degree
of land development. A good prediction variable for bacterial pollution
parameters was found to be the general sanitary conditions of the site.
BOD, concentrations decreased with increasing runoff flow, but the total
amount of BOD, increased with the increasing flow.

In residential areas, the runoff pollution per unit area increased with
population density and/or the number of developed parcels, In commercial
and industrial areas, runoff pollution per unit area actually decreased
with the number of persons visiting the area, This was explained by sug-
gesting that, as the number of daily visitors increased, the degree and

frequency of maintenance operations increased.

2, Characteristics of Street Surface Contaminants

A study by the American Public Works Association!? was conducted in Chicago
during the summer of 1967 to determine the factors in the urban environment
which contribute to the pollution of stormwater runoff, Although several

sources of runoff pollution were recognized in the study, including street


EPA 440/9-75-004
December 1974

WATER QUALITY MANAGEMENT PLANNING
FOR URBAN RUNOFF

By

Gary Amy
Robert Pitt

Rameshawar - Singh
Westly L. Bradford
Michael B. LaGraff

Project Officer

James Meek
Chief, Planning and Standards Branch
Water Planning Division
Office of Planning and Standards
U.S. Environmental Protection Agency
Washington, D.C. 20460


Section IV

TREATMENT, ABATEMENT, AND DISPOSAL OF URBAN RUNOFF


(3) Determine the average street surface runoff rate, Yavg,
by dividing the volume of street surface runoff in each
time interval by the product of [At (expressed as minutes)
times the amount of street surface within the study area
(expressed as acres) times the constant 60].

(4) The value of P, for the first time interval can be de-
termined by multiplying the contaminant load (expressed
as pounds per acre of street surface) by the amount of
street surface area (expressed as acres). Values of Po
for subsequent time intervals can be determined by sub-
tracting the P value of the previous time interval from
the P, value of the previous time interval.

(5) Values of AP for each time interval can be determined
from the previously described pollutant removal equa-
tion,

(6) Add each calculated value of AP to the summation of
AP values.

(7) The concentration of total solids for each time in-
terval can be determined by dividing the value of Ap
by the volume of impervious area runoff and multiply-
ing the result by 16,000, It should be explained
that runoff from total impervious area is used in
step 7 in contrast to steps 3 through 6 when only
the street surface runoff is utilized. The reason
for doing so is obvious because essentially all
urban contaminants are assumed to derive from
street surfaces and they are removed by street sur-
face runoff. These contaminants mix with the total
impervious runoff flowing through gutters and sewers
finally, neglecting the runoff contribution from per-
vious areas..

Using the above procedure, a series of valués presenting the total solids
concentration and the accumulative solids load at corresponding time in-
tervals can be calculated and plotted against time. The graphical plot

of concentration versus time represents the resultant pollutograph while
the graphical plot of load versus time represents the resultant loado-

eraph, The combination of an impervious area hydrograph, a pollutograph,
and a loadograph superimposed upon the same coordinate system shall sub-

sequently be referred to as a quantity/quality hydrograph as shown in
Figure 16b.

I-52


5.

10.

11.

12.

13.

14,

15.

16.

17.

18.

INSTRUCTIONS

REPORT NUMBER
Insert the EPA report number as it appears on the cover of the publication.

LEAVE BLANK

RECIPIENTS ACCESSION NUMBER
Reserved for use by each report recipient.

TITLE AND SUBTITLE . ni +

Title should indicate clearly and briefly the subject coverage of the report, and be displayed prominently. Set subtitle, if used, in smaller
type or otherwise subordinate it to main title, When a report is prepared in more than one volume, repeat the primary title, add volume
number and include subtitle for the specific title.

REPORT DATE . a
Each report shall carry a date indicating at least month and year. Indicate the basis on which it was selected (e.g., date of issue, date of

approval, date of preparation, etc.).

PERFORMING ORGANIZATION CODE
Leave blank.

AUTHOR(S)
Give name(s) in conventional order (John R. Doe, J. Robert Doe, etc.), List author’s affiliation if it differs from the performing organi-
zation.

PERFORMING ORGANIZATION REPORT NUMBER
Insert if performing organization wishes to assign this number.

PERFORMING ORGANIZATION NAME AND ADDRESS
Give name, street, city, state, and ZIP code, List no more than two levels of an organizational hirearchy.

PROGRAM ELEMENT NUMBER
Use the program element number under which the report was prepared. Subordinate numbers may be included in parentheses.

CONTRACT/GRANT NUMBER
Insert contract or grant number under which report was prepared.

SPONSORING AGENCY NAME AND ADDRESS
Include ZIP code.

TYPE OF REPORT AND PERIOD COVERED
Indicate interim final, etc., and if applicable, dates covered.

SPONSORING AGENCY CODE
Leave blank.

SUPPLEMENTARY NOTES
Enter information not included elsewhere but useful, such as: Prepared in cooperation with, Translation of, Presented at conference of,
To be published in, Supersedes, Supplements, etc.

ABSTRACT
Include a brief (200 words or less) factual summary of the most significant information contained in the report. If the report contains a
significant bibliography or literature survey, mention it here.

KEY WORDS AND DOCUMENT ANALYSIS
(a) DESCRIPTORS - Select from the Thesaurus of Engineering and Scientific Terms the proper authorized terms that identify the major
concept of the research and are sufficiently specific and precise to be used as index entries for cataloging.

(>) IDENTIFIERS AND OPEN-ENDED TERMS - Use identifiers for project names, code names, equipment designators, ete. Use open-
ended terms written in descriptor form for those subjects for which no descriptor exists.

(c) COSATI FIELD GROUP - Field and group assignments are to be taken from the 1965 COSATI Subject Category List. Since the ma-
jority of documents are multidisciplinary in nature, the Primary Field/Group assignment(s) will be specific discipline, area of human
endeavor, or type of physical object. The application(s) will be cross-referenced with secondary Field/Group assignments that will follow
the primary posting(s).

DISTRIBUTION STATEMENT
Denote releaablity to the public or limitation for reasons other than security for example “Release Unlimited.” Cite any availability to
the public, with address and price. °

19. & 20. SECURITY CLASSIFICATION

21.

22.

DO NOT submit classified reports to the National Technical Information service.

NUMBER OF PAGES
Insert the total number of pages, including this one and unnumbered pages, but exclude distribution list, if any.

PRICE
Insert the price set by the National Technical Information Service or the Government Printing Office, if known.

EPA Form 2220-1 (9-73) (Reverse) ‘4#U.S, GOVERNMENT .'RINTING OFFICE:1975 631-578/905 1-3


Calculations based on a hypothetical but typical U.S. city* indicated that
the pollution load of street surface runoff during the first hour of a

moderate-to-heavy storm (brief peaks to at least 0.5 in./hr) would be many
orders of magnitude greater than the same city's untreated sanitary sewage
during the same time period. A comparison of the pollution load of runoff

with raw sewage and secondary treatment effluent is shown as follows:

CALCULATED QUANTITIES OF POLLUTANTS WHICH
WOULD ENTER RECEIVING WATERS IN A HYPOTHETICAL CITY

Street surface

runoff
(following Raw sanitary Secondary
1-hr storm) sewage plant effluent
(1b/hr) (1b/hr) (lb/hr)
Settleable plus
suspended solids 560,000 1,300 130
BOD, 5,600 1,100 110
coD 13,000 1,200 120
Kjeldahl nitrogen 880 210 20
Phosphates 440 50 2.5
Total coliform 10 10 10
bacteria (org/hr) 4,000 x 10 460,000 x 10 4.6 x 10

Note: Since the above calculations were based only on a 5-day accumulation
of street litter, the above discharge of contaminated runoff could
conceivably occur many times in a year,

*The hypothetical city has the following characteristics:
@ Population - 100,000
e@ Total land area - 14,000 acres
e@ Land-use distribution:
residential - 75%
commercial - 5%
industrial - 20%
e Streets (tributary to receiving waters) - 400 curb miles
e@ Sanitary sewage - 12 mgd


€9-1

Cubic Feet Per Second

Pollutant

Concentration

Hydrograph

Accumulative.
Pollutant

{bons

Figure 20,

Total

Solids BOD

Conc, Cone,

(mg/f) — (mg/f)
H1200 +24
Fi000 +20
800 «+16
F600 H9
t400 +8
F200 =F 4

coD
Conc.

(mo/e)

24

P18.

P12

A Sample Quantity/Quality Hydrograph Reflecting Several Quality Parameters

Pounds
of
Total
Solids

F150,000

[100,000

[50,000

Pounds
of
BOD

f- 1000

Pounds
of
coD

f- 4500

f- 1500



INTRODUCTION


19,

20.

21.

22,

23.

24,

25.

26,

27.

28,

Loading ~ the average amount of total solids found on street surfaces

per unit distance per day (i.e., pounds/curb mile/day).

Manganese (Mn) - an element which produces a brownish color in
laundered goods and impairs the taste of beverages, including

coffee and tea,

Mercury (Hg) - a heavy metal which can cause severe neurological dis-
orders when it is ingested in large quantities. (Particularly dan-
gerous because small quantities can be concentrated by aquatic or-

ganisms which are frequently eaten by man).

Methoxychlor ~ an organochlorine insecticide [1,1,1-trichloro-2,

2-bis (p-methoxyphenyl) ethane].

Methyl Parathion - an organophosphate insecticide [0,0-dimethyl
O-p-nitrophenyl phosphorothioate 1.

Micron (wv) - a unit of length equal to 1 x 10° meters,

Micrograms Per Gram (ug/g) - the micrograms of a specific pollutant

found per gram of total solids.

Micrograms Per Kilogram (ug/kg) - the micrograms of a specific

pollutant found per kilogram of total solids.

Milligrams Per Liter (mg/f) - the milligrams of a substance per liter

of water on a dry weight basis.

Most Probable Number (MPN) - a statistical indication of the number

of bacteria present in a given volume (usually 100 mf),


First, compute the standard error of the difference between any two means,

x, and x,, as

1 2’

OO, = *2
o Oo, + OB
Then the Student t is defined as
x, - x,
Student t = i 2
%

The probability that the Null Hypothesis (that x - % = 0) is correct
is given in tables of the Student t distribution listed in any good
statistics text or in Standard Mathematical Tables (Chemical Rubber

Publishing Company, Cleveland, Ohio).

To assist the planner in learning and using this technique, two sample

problems are presented:

Problem 1:

Question: Is the mean COD concentration in solids found
in heavy industrial areas significantly different

from that found in residential areas?

Given: (1) Heavy Industry COD = 88,000,
(2) Residential COD = 82,000,

40-50%, average 45%

ul

Subscript e
Subscript b = 10-20%, average 15%

tl

36,000

x
©, = 80,000 x 0.45

a

12,300

we *

= 82,000 x 0,15

q, = /36,000° + 12,300

Student t =

38,000

A-35


Table 13. PARAMETERS WHICH AFFECT STREET SWEEPING PERFORMANCE

Fixed Loading: Mass level
Particle size
Uniformity

Surface: Type
Condition

Sweeper: Type

Controllable Sweeper
operation: PUB® type

PUB rpm

PUB diameter
PUB strike
Forward speed
Number of passes
Gutter broom
Debris deflector

Untested Operator skill

a, PUB - Main Pickup Broom

From Figure 35, one can see that a flusher removes more materials per
"unit effort" than a sweeper, It must be remembered that a flusher does
not remove the contaminants from the receiving water system, but actu~

ally discharges the pollutants during periods of no rainfall.

Iv-9


D, TREATMENT

The treatment of urban stormwater runoff has been approached in two
major ways over the past several years, One approach has seen the
development of varied means of storing the peak flows and discharging
them to conventional treatment plants during low flow periods. These
peak flows would normally be discharged untreated. The second approach,
which can be used in conjunction with storage, has seen the development
of specialized treatment processes to deal specifically with quantities

and types of pollutants found in stormwater runoff.

This section briefly outlines some of the common treatment and storage
techniques that have been used or show promise, This section is not
meant to supply sufficient information to design a complete treatment
scheme, but to give the planner a general idea of the methods available

and some costs,

1. Storage and Treatment

Although urban stormwater runoff is similar in many respects to raw
sanitary sewage and is amenable to many of the same treatment processes
certain aspects of runoff create unique treatment problems. The main
problems encountered in treating urban runoff include (1) the intermit-
tent and random occurrence of the runoff event with correspondingly

high flow rates, and (2) heavy loadings of solids.

Perhaps the most serious problem involved in treating urban runoff is
created by high flow. rates. The hydraulic capacity of most treatment
plants is not sufficient to treat the total flow during high flow rate
periods of runoff, To overcome this obstacle, either the flow rate of
the runoff water entering the treatment process must be reduced, or the
hydraulic capacity of the treatment process must be increased, or the
detention time must be decreased, Usually a combination of those

approaches is the most desirable solution.

Iv-15


Lo-W

rrr c si om AA Sc A mS R oS M LOM Sms CoD ooh POL HOD CRE a a
Tuscan 4 3 20 2 200000 520 2730

nN aL 29 2 312000 450 ‘380
cHICAGS 13 20 15 22 22 3100 53100 70, 523
CHICAGS 1 3 20 20 22 32 8 e770 61300 63 377
CHICAGS 1 3 20 20 22 32 00 «3260030 405
CHICAGS 1 3 20 20 12 7 2 49 3289 24800 ak 525
cHICAGS 1 3 20 40 a2 72 9830 72800 109 523
CHICAGO 13 20 io 22 32 96 (1980 32100 a8 4e2
TULSA 2 0 20 89 50 e222 22 67390 10000 3300 2700
TULSA 2 9 20 1143 20 142 35 39300 298000 3000 1800
TULSA 2 0 39 443 20 24 2 +51 41 28300 247000 1600 1900
TULSA 2.0 20 95 50 32 a2 33 28000 207000 1500 4200
TULSA 2 0 20 1162 20 14 2 22 28 43900 188000 3000 1400

Table A-20, LANDSCAPING BEYOND THE SIDEWALK 2 - TREES

cry c sw PD AA IF ADT S C A mS R S M LOAD Bons cD POH TPO N03 NBA ORG RR a a
CHICAS 13 20 50 198033 302 188 © B10 29500 at 773
CHICAGS 13 25 15 1828002 3 392 121 2030 3800024 345
CHICAGE 13 20 20 24000 BO 3.2 135 ©6320 4560073 670
CHICAGE 13 20 50 190704 3 2 188 2280 2860020 364
CHICAGE 13 20 20 1620 2 3 7 2 153 3220 38600 30. 356
TULSA 2.0 3¢ 40 5 455 10600 2 1 3 +20 46 29300 163000 3200
TULSA 2 9 20 1366 20 +31 3800 3637 2% 24000 277000 2400
BALTIMORE = «22 Be 6700 1 1 3 26 1 4 100 210 120 19000 1700 290 95 24
BALTIMORE = 2-2 38 27000 1 0 3 we 8 18 264 210 23000 2100 500 7 33
SEATTLE 5 3 22 6900 1 1 3 12 148 239 100 37000 3000 490 40 8
SEATTLE 83 25 12300 1 2 3 12 142 254 48 59000 2600 480 39

Table A-21, LANDSCAPING BEYOND THE SIDEWALK 3 - LANDSCAPED BUILDINGS


Table A-2, These submatrices are shown in Tables A-6 through A-22,
Data from URS Research Company's earlier studies that had collected
data on the condition and type of street surface was grouped by hand

into two street surface types. These groups are not shown,

Each column of data was first scanned by eye and extreme values were dis-
carded in pairs -- a high and a low. The total number of points dis-
carded did not exceed 10 percent of the number available. A single

point was discarded only when it was one to two orders of magnitude
different from the bulk of the remaining data in the column, The mean,
standard deviation, range, and number of data points were calculated

and recorded, Standard deviations for means of less than 5 data were
considered unreliable and not recorded. The same calculations were
performed on the set of all data, These basic statistics are listed in

Table A-23.

These basic statistics are useful for testing whether the analysis of a
single sample is significantly different from the mean of the published
analyses, But in its present form, Table A-23 is much too complex and
cumbersome to enable a planner to use it to predict loading rates and
composition or to make decisions about whether a mean value in a par-
ticular subset is significantly different from the mean of the set of
all data, To simplify the presentation of these data, the standard
error of the mean () was calculated as

&= ir y>10 or & = if N<10

Va

me
Viq-1
where o is the standard deviation and 7 is the number of available data,

*
Then o was calculated as a percent of the mean as
* *
ho = (a/x) x 100

- *
where x is the mean of the column of data, The %o, expressing the per-
cent standard error of the mean, is presented as a letter subscript that

A-16


sS-I

DIAMETER OF CIRCULAR PIPE FLOWING FULL*

Vv
1.0
s
i + 0.00001.
£ L1.5.
a
3
+ 0.00
g 005 ele.o
FS +0.0001 8
z a
3 oc
3 2
$s + 0.0005 G
a w fred
? & [0.001 =
& s z
E ° z
F
a o
3 °o
5 a
>
3 }0.01
&
3
3 + 8.0
3 +0.05 9.0
i L0.10 L10.0
=
0.20 12.0
+ 14.0

Figure 18, Determination of Lag Time

* If the depth of the water flowing in the pipe is at
least 30% of the pipe diameter, the resulting esti-
mate of lagtime will at least be within + 20%.

LAG TIME IN SECONDS

T

50,000

+ 10,000

+ 5,000

+ 1,000
500

f- 100

L-5o

10

100,000

Ss

DISTANCE OF TRAVEL IN FEET

}- 100,000

- 50,000

10,000

~ 5,000

t- 1,000

fF 500

f- 100

+ 50

-10


9TWI

Table 7. EIGHTY PERCENT CONFIDENCE LEVEL*

Lbs/curb
ni/day Concentrations in icrograns per gran of dry nolid tele _
Category Loading” B00, COD "GPO, PO, NO, WH, -OreN Cd Cr SCS Poa NE Sra TooLI” = Feo’
Land Use 10 Open space
20 Residential 14,000, 82,000, 850, $50, 1,800, 93, 1,430, 28,
‘30 Commercial 58,700, 269,000, 2,250, 1,580, 6,430, 133, 3,440, 48, 520,
40 Light industry
7
‘50 Heavy industry 2 8, 28,600, 1,160, $70, 8.265,
‘Climate 1 Northeast 292, 139, 17, 700, 870, 363, 2, 27, 260, 4,485,
2 Southeast 103, 29,100, 2,240, 1 1970, 137, 1,370, 21, 28, 7.084,
4 Southwest 50, 470, 241, (78, 2,520, 57%, 15, 5. 7E6,.
5 Northwest 30, 246, 34,500, 2,600, 10, 480, 6.8E5, 1.184,
Average Daily < 500 1,210, 252, 6.9E4
traffic 9. 83,000, 74 49, 18,900, 1,060, 17, 34 sass,
No. /day 500 ~ 5,000 +500, 83,000, 7Al4. 18, +900, 1,060, a Me AES
5,000 - 15,000 18,
> 15,000 82, 357, 3. ‘SES,
1 «Grass. 32,400, 1,370, 21, 8.355, 1 AEA,
2 Trees 43, lL 1E7,
3 Landscaped
buildings 93, ‘3.5E5, ag
4 Hard surfaces 13, 700, 78,000. 780, 461, 2,370, 16, a 15S.
Street Surface 1 Asphalt 2,470, 1,770, 18,
Material “
2 Concrete 38, 72,000, 3,520, 2,600, 6,680, 1,280, 45, 292,
All data 156, 19,900, 140,000, 1,280, 2,930, 804, 2,640, 2,950, 3. a1, 104, 23,000, 1, 10, als, 35. 21 370, 2, 5E6 1.785,

“only those subset means

aumber of peruitted substitutions = 103.

*colitora counts are expressed in conputer notation, 1

re shown which differ from the moan of the

Percent Standard Error of the lean Subscripting Code:
ES = 10°

t of all date at the 80-percent confidence level (Student t > 1.39, Degrees of Freedom 2 10). Total

220-9, b= 10~ 19, c= 20 = 29, d = 30 - 39, e = 40 - 49, f = 50 - 62.


13.

14,

15.

16,

17,

18.

19.

20.

21,

22,

23.

24,

25.

26.

27,

EFFECT OF URBAN GROWTH ON SEDIMENT DISCHARGE, NORTHWEST BRANCH ANACOSTIA
RIVER BASIN, MARYLAND, F.J. Keller, U.S.G.S, Prof. Paper 450-C, C129-131,

"Effect of urbanization on storm water peak flows," Pedro C.C. Da Costa,
JOURNAL SANITARY ENGINEERING DIVISION, ASCE, SA2:187, 4/70.

EFFECTS OF DEICING SALTS ON WATER QUALITY AND BIOTA; Literature review and
recommended research, R.E, Hanes, L.W, Zelazny, and R.E, Blaser, National
Cooperative Highway Research Program Report 91, 1970,

"Effects of urbanization on storm water runoff quality: A limited
experiment, Naismith Ditch, Lawrence, Kansas," E.E. Angino, L.M. Magnuson,
and G,F, Stewart, WATER RESOURCES RESEARCH, 8(1):135, 2/72.

"The effects of urbanization on water quality,” E.C. McGriff, Jr., J.
ENVIRON, QUALITY, 1(1):86-88, 1972.

"Elemental composition of suspended particulate matter in metropolitan
New York," Norman L. Morrow and Richard S, Brief, ENVIRONMENTAL SCIENCE
AND TECHNOLOGY, 5(9):786-789, 9/71.

ENVIRONMENTAL IMPACT OF HIGHWAY DEICING, Edison Water Quality Lab for
Water Quality Research, EPA, 11040 GKK, 6/71.

EVALUATION OF STORM STANDBY TANKS, COLUMBUS, OHIO, Dodson, Kinney and
Lindblom for Water Quality Office, EPA, 11020 FAL, 3/71.

"Five cities try to stop storm pollution," ENGINEERING NEWS-RECORD, 67,
12/66,

"Freeway runoff to be treated," PUBLIC WORKS, 102(5):104, 5/71,

HIGH RATE FILTRATION OF COMBINED ‘SEWER OVERFLOWS, Hydrotechnic Corp, for
Office of Research and Monitoring, EPA, 11023 EYI, 4/72.

HYDROGRAPH SYNTHESIS FOR WATERSHED SUBZONES FROM MEASURED URBAN PARAMETERS,
J.B. Evelyn, V.V.D. Narayana, J.P. Riley, and E.K. Israelsen, Utah State
University, 8/70.

INVESTIGATIONS OF POROUS PAVEMENTS FOR URBAN RUNOFF CONTROL, Franklin
Institute Research Labs, for Office of Research and Monitoring, EPA,
11034 DUY, 3/72,

"Lead in a suburban environment," P.R, Atkins, JOURNAL OF THE AIR POLLUTION
CONTROL ASSOCIATION, 19(8):591-594, 8/69,

"Mercury and other metals in urban soils," David H. Klein, ENVIRONMENTAL
SCIENCE AND TECHNOLOGY, 6(6):560-562, 6/72,

c-14


400 +

Cubic Feet per Second
Nn w
o o
o o
n l

100

Hydrograph

Time

Figure 26. Composite Quantity/Quality Hydrograph of Example 8

II-18

Total Solids Concentration (Milligrams per Liter)

1000

a
s

T
a
8
Total Solids Load(Pounds)

250



runoff) within the higher percentage ranges of contaminant removal, Con-
sequently, as the total inches of runoff increase, the total pollutant
load removed will increase while the average pollutant concentration will
decrease due to dilution from the additional increments of runoff re-

quired to remove contaminants within the higher percentage ranges,

Figure 3 describes average pollutant concentration as a function of
street surface runoff and contaminant removal. This curve confirms
that average pollutant concentration decreases as the total inches of

runoff increase.

Therefore, a storm event which produces a large volume of runoff will
contribute a greater pollutant load to a receiving water than a storm
event which produces a smaller volume of runoff, However, runoff from
the latter will contain a greater average pollutant concentration, It
is strongly recommended that the user keep the above phenomenon in mind

while selecting a storm event for assessment.

° Basic Procedure, It is recommended that the user select a "typical"
storm event which has a duration of 30 minutes and would likely occur
several times a year in the geographical vicinity of the study area, A
storm with an occurrence frequency of six months or less would be appro-
priate (often a local weather bureau can provide this kind of informa-

tion).

If local sources of information cannot provide statistical storm frequency
data, it is recommended that the user select a one-year storm with a dura-

tion of 30 minutes, using the frequency curve given in Figure 4,
The general procedure for selecting a storm event is as follows:

(1) Select a "typical" storm event which has a duration of
30 minutes and would likely occur several times a year
in the geographical vicinity of the study area, If
such a storm event is indeterminable, select a l-year

1-23


Table A-1, DATA ACQUIRED FOR THE ANALYSIS

Item Parameter Abbreviation
1 City
2 Climate c
3 Season”
4 Land use* LU
5 Population density PD
6 Average age of the structures
in the area, in years AA
a 7 Fraction of the area covered
38 by impervious material IF
2 8 Average daily traffic
# (number/day) ADT
“ 9 Type of street surface” s
8 10 Condition of the street
3 11 Type of landscaping in the
8 area beyond the sidewalk A
a 12 Fraction of the area as
road surface FRS
13 Days since last rain
14 Days since last swept
15 Method of cleaning”
16 Loading rate in pounds per
curb mile per day LOAD
2 17-32 Organic and inorganic constituents in pe/Ee
2 of dry solids. Self~-explanatory as follows:
g BOD;, COD, Ortho P04, total PM, NO3, NHg,
£ organic N, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Sr,
é and Zn.
of 33-34 Coliforms, total coliforms and fecal coli-
3 forms in numbers per gram of dry solids
Fy based on the most probable number methods (MPN).
& 35-42 Pesticides and toxic organics: endrin,

dieldrin, PCB, methoxychlor, DDT, lindane,
methyl parathion, and DDD in wg/kg of dry -
solids,

"For numerical codes see Table C-2.


5.0 QUALITY OF RUNOFF

In addition to representing the flow of runoff as a function of time,
there is a definite need to express the quality of runoff as a function
of time, Appropriate graphical representations were felt to be a "pol-
lutograph" (shown in Figure 15a) and a "loadograph" (shown in Figure 15b).
A pollutograph portrays pollutant concentration as a function of time

while a loadograph portrays pollutant load as a function of time.

The procedure to be utilized in developing pollutographs and loadographs
is based upon studies conducted by Metcalf & Eddy? and URS Research Com=
pany.* Both of these studies assumed that the amount of pollutants washed
off a street surface, dP, in any time interval, dt, is proportional to the

amount of pollutants remaining on the street surface, P:

-dP
dt — xP
which integrates to
_ “kt
Po Po= Po Q -e )
where Py = initial loading in pounds
P = pounds remaining after time, t
k = constant
t = time
Po - P= pounds washed away in time, t

The constant, k, is a function of runoff. To determine k, it was assumed
that a uniform runoff of 0.5 inch per hour will wash off 90 percent of
the initial pollutant load in one hour (this assumption was verified in
the URS study). This leads to the equation:

Pp - = -
P Po (1


r. Total Coliform Counts are Lowest in:

1.

2.

Heavy industry areas
The northwest
Areas with heavy vehicular traffic (15,000 ADT)

Areas with grass or no landscaping (and highest in tree

covered areas)

s. Fecal Coliform Counts Are Lowest in:

*1,

No significant differences between land use categories;
unexpected because generally it is thought that pet feces

cause higher fecal coliform counts in residential areas
The northwest
Areas with heavy traffic (>15,000 ADT)

No significant differences with landscaping

Generally the trends observed were expected,or, at least, not unexpected.

In eight cases the data indicated that preconceived notions were not sup-

ported by observations,

A-41


Urban runoff loads as

Raw
Domestic sewage percentage of sewage loads

Constituents (1b/day/acre)  (1b/yr/acre) During runoff Annually
Suspended

solids 1.5 540 2400 160
coD 2.6 960 520 33
BOD, 1.5 540 110 7
Total PO, 0.19 68 70
Total N 0.23 82 200 14

A stormwater sampling program was performed by Bryan® in Durham, North
Carolina, between May 1969 and February 1970, to determine the quality of
storm runoff and the effect of land use on the quality. The 1067-acre
(433 ha) drainage basin studied comprised a mixture of land uses typical
of urban areas in North Carolina, The population density averaged about

9 persons per acre (22,5/ha).

The water quality characteristics of the sampled runoff were in general
agreement with the findings of other studies. The total solids contribu-
tion of the urban runoff was substantially larger than the expected average
raw sewage wastewater from the same basin. The BOD, of the runoff was esti~
mated to equal sanitary effluent from a secondary treatment plant, while
COD was greater than raw sanitary effluent from a strictly residential,
average, urban area. The contribution of phosphates was nominal in com-

parison with domestic wastewater.

Obvious relationships between land use, population density, and other
numerical characteristics of the subbasins and the measured pollution

parameters could not be established because of the amount and type of
data generated,


The method of runoff coefficient assumes that the rate of runoff is a

percentage of the rate of precipitation. If this is true, then:

where R = runoff rate in inches per hour
P
k

precipitation in inches per hour

a

runoff coefficient (a dimensionless constant varying
from 0 to 1,0)

Values of the runoff coefficient, k, for impervious surfaces are given
in Table 8, These values of k can be used directly in conjunction with
the above equation when predicting the runoff rate from an impervious

surface. An example of the runoff coefficient method is given in Example
3 of Section II.

Table 8, VALUES OF RUNOFF COEFFICIENT, k

Impervious Surfaces Approx, k
Flat (<2% slope) 0,80
Moderate (2 to 7% slope) 0.85
Steep (>7% slope)’ 0.90

3.3.2 Selection of Storm Event

Theoretically, any storm event (and its resultant runoff) can be selected
for an assessment of urban runoff, A particular storm event can be char-
acterized by its duration, its average intensity, and its frequency of

occurrence,

The implications of selecting a specific storm event are two-fold; the
selected storm event will (1) generate a certain volume of runoff and

(2) remove a certain percentage of available street surface contaminants,

I-19


Ts-1

FIGURE 16a.

POLLUTOGRAPH AND LOADOGRAPH WORKSHEET

1 2 3 4 5 6 7 6
ISTREET SURFACE RUNOFF > TOTAL TOTAL SOLIDS
At VOLUME Tavg ° AP ZAP VOLUME CONCENTRATION|
(min) (cu ft) (in. /hr) (1b) (1b) (1b) (cu £t) (mg/2%)



8c-V

ary

ANN ARBOR
ANN ARBOR

TUSceN

‘SHOP SCENTER
7

1
1
1
1

1
1
1
1

ONDE ee PNUN TSS ERNE Ee EE EE Ee POOR O OMNES eee

COLIN RANA NRNON NNN OMNMMEEHH se FE FOOOCOOCOUWUWWOHWOOO FUR @

Table

peewee

Pee ee eee eee OE EEE HEE SEED HEED EES ESET E EE DE TET EEE Rees y

Pee neem cane seer ence pmenenec te on ee pate (Danae mene bees tans eben ee
PANEER ROH HH NINO VAN NOVOHENEN EN

A-22,

a
E

+15
+23

ODS COD-«oPO4 TOA MO} | NG ORGN cD RR

38800 650 2620 650 595, 535
30700 960 2770 800 730 365
21300 220 2130 440
201000 240
2B ane BE so ae
12 26700 «3B
12 24800 7
12 23000 0
3700 «17000 1400 72
13 2 at
Had 8
Hig
BER
RHE
o 72 30
o 8 2 St
2 EE ad
fig
£3
39 3 0
59 2 3
39 2 204
218
2 ie 1 ays
9 rs Ld
3
fob
:
ei
rf a
Bod

LANDSCAPING BEYOND THE SIDEWALK 4 - NO LANDSCAPING

7
15

650 348
370 2070
220

85

ort

Saanae

gee

ve avers sumereey


planner to find quickly the best data available in predicting loading
rates and chemical composition, The use of these tables is described

in detail in the text.

An urban planner may be concerned whether or not one mean value is signi-
ficantly different from another, Table A-24 is constructed so that he
may perform a Student t test of significance, some example results of

which were mentioned in the last section,

The table is constructed so that (1) the standard error of the mean falls
into a group which has numerical limits as narrow as feasible while still
permitting efficient presentation, and (2) standard errors of the mean
are presented only for those values where the number of samples was

five or greater, so that the degree of freedom used when consulting
tables or graphs of the Student t distribution is always greater than

ten, All discussion is based on 10 degrees of freedom,
The Student t is performed as follows:

Definitions
o= standard deviation
*
o = standard error of the mean

*
o= -<£ for n>10 and —& for n<10

Vn n=1

%o = percent standard error of the mean; this is the
value indicated by superscript in the tables

* x=
ho = (0/x) 100
x = sample mean

q,= standard error of the difference

A-34


EXAMPLE 9

An urban watershed consists of 1,500 acres of impervious surface and
1,000 acres of pervious surface with lawns and sandy soils, The water-
shed is characterized by a steep slope and has an average contaminant
loading of 300 1b/curb mile, A rainfall with an intensity of 0.32 in./hr
occurs for 60 minutes. What is the average total solids concentration of
the resulting runoff? What is the total load of solids removed by the

specified storm event?

Again using the impervious surfaces only,

imp = 0.90

= &kP
0,90 (0.32 in./hr) = 0.288 in./hr

Wl

From Table 9, it can be seen that a runoff rate of 0.288 in./hr which
lasts for 60 minutes will remove about 73 percent of the residing urban
land contaminants.

Volume of Runoff Runoff Rate X Runoff Duration X Area X 3,630

Volume of Runoff (0.288 in. /hr): (1.0 hr) (1,500 acres) (3,630)

Volume of Runoff 1,568,160 cu ft

mt, of Contaminant Removal = Contaminant Load X Area X (% Removal/100)

II-19


o-Vv

Figure A-1, Climate Zone Codes for the Data Matrix
and Cities for Which Data Are Available


Street surface contaminant accumulation is a function of street sweeping
frequency, street sweeping removal effectiveness, and antecedent rain-
fall events, The accumulation of street surface contaminants can be
minimized by increasing the frequency of street sweeping operations.
Commercial areas are generally swept more often than other land use
areas, which explains the lower contaminant loadings found in commercial

areas,

The removal effectiveness of street sweeping operations can be improved
by sweeping an area more than once, Repeated passes over the same area
can effectively reduce the amount of contaminant material remaining on
a street surface. Figure 31 shows typical removal effectiveness vs the
number of passes of a street sweeper, based on a surface loading of

10 e/tt?.

The practice of repeated sweeping passes over the same area and the
practice of increased street sweeping frequency are essentially mu-
tually exclusive. Since there is only a finite number of available
street sweeping vehicles, an increased utilization of one practice will
result in a decreased utilization of the other, This phenomenon can

be partially circumvented by the acquisition of additional street

sweeping vehicles.

Besides increasing the sweeper frequency, street pollutant removal may
be improved by more efficient use of existing equipment and practices,
Table 13 shows some common parameters that affect street sweeping per-
formance. Figures 32 through 35 show how some of these parameters af-

fect removal effectiveness,

Vacuum-type sweepers have shown promise in achieving a fairly high re-
moval effectiveness, including the small particle size range of contam-
inant material, but their effectiveness falls off dramatically if the
streets are wet. On the contrary, broom-type street sweepers are es-

pecially prone to difficulty in removing small particle sizes,

Iv-7


4.3 Definition of a Hydrograph and a Unit Hydrograph

A thorough assessment of urban runoff pollution requires more than just
an estimate of the impervious runoff volume from a study area, Since

the removal of street surface contaminants varies according to the rate
of street surface runoff, a method which describes impervious runoff as

a function of time is required for a thorough analysis.

The concept of a hydrograph can be used to describe runoff resulting

from a rain event. A hydrograph portrays the rate of runoff as a func-
tion of time. The runoff rate corresponds to a flow rate measured at a
designated inlet located within a particular study area, A sample study

area and its corresponding hydrograph are shown in Figure 5.

A hydrograph describes the rate of runoff from a study area during a
specific storm event. Unfortunately, an individual hydrograph is not
directly applicable to storm events with different intensities and/or

durations,

To portray the runoff characteristics of a given urban watershed for
storms of varying intensities with a single hydrograph requires a nor-
malization method to describe the general runoff characteristics of
the given watershed. The normalization method employed is that of

the unit hydrograph.

A unit hydrograph is defined as "the hydrograph of direct runoff re-
sulting from one inch of effective rainfall (rainfall which causes run-
off) generated uniformly over the basin area at a uniform rate during

a specified period of time or duration."*

The concept of a unit hydrograph as umes that (1) the effective rain-

fall occurs at a uniform rate, and (2) the effective rainfall is uni-

formly distributed over the watershed with respect to time and area,

1-29


Elevation = 10 feet

Bx Pervious

Main Drainage Channel
LO impervious

Figure 21, Sample Study Area for Example 1

Scale: 1°=200°
II-2


TABLES:
(Continued)

Number

A-10
A-11
A-12
A-13
A-14
A-15
A-16
A-17
A-18
A-19
A-20
A-21

A-22
A-23

A-24

Land Use 50 - Industrial. . . 1. 2 ese eee eae

Climate 1 - Northeast . 2... 2 2 6 ee 2 ee ewe
Climate 2 - Southeast . 2. . 0 se ee eee eevee
Climate 4 - Southwest... 6. 6 1 eee ee woe

Climate 5 - Northwest . . 1... 6 eee eee eee
Average Daily Traffic - Less Than 500,......
Average Daily Traffic - 500 to 5000 ........
Average Daily Traffic - 5000 to 15,000,......
Average Daily Traffic - Greater than 15,000 ....
Landscaping Beyond the Sidewalk 1 - Grass . . .. «
Landscaping Beyond the Sidewalk 2 - Trees .....

Landscaping Beyond the Sidewalk 3 - Landscaped
Buildings . . 2 6 6 6 es es ee ee ee ee eo ee

Landscaping Beyond the Sidewalk 4 ~ No Landscaping,

The Basic Statistics of the Available Data,
Including the Mean, Standard Deviation, Range,

and Number of Samples in the Set of All Data

and in 19 Subsets of the Data... .... se ee

Means and Percent Standard Errors of the Means
of the Set of All Data and of 19 Subsets of the
Data, . 6 2 eee ee ee ee ee ee he ee

XII

Page

A-20:
A-20
A-21
A-22
A-22
A-23
A-23
A-24
A-25,
A-26
A-27

A-27
A-28

A-29

A-33


CONTENTS

Section

INTRODUCTION. . 2 2 1 ee ee ee ee ee

Manual Format. ......+ +++.

AN ASSESSMENT OF URBAN RUNOFF QUANTITY
AND QUALITY. .

1.0 General Considerations

2.0
3.0

Definition of a Study Area .

Data Requirements. . .... 1... eee

3.1
3.2

Study Area Characteristics,

Determination of Contaminant
Loading Rates and Materials

Composition ,

3.2.1 Use of the Tables.
3.2.2 Levels of Sophistication
in Using the Tables.

Storm Event Characteristics and
Impervious Runoff Rate.

3.3.1 Method of Computing Runoff
Runoff Rate From Impervious
Surface. see ee ee

3.3.2 Selection of Storm Event .

Determination of Quantity and Flow
of Runoff. . 6 6 1 ee ee ee ee

4.1
4.2
4,3

4.4

General Assumptions and Background,
Determination of Volume of Runoff .

Definition of a Hydrograph and
Unit Hydrograph .

Development of Unit Hydrograph
for Entire Study Area... .

Development of Unit Hydrographs
for Impervious Area and Street
Surfaces. .

Modification of Unit Hydrographs to
Reflect Specific Runoff Rate,

Vv

Page

1-3
I-5
I-5

1-27
1-27
1-28

1-29

I-31

I-39

1-45


litter, catch basins, roof discharges, and various chemicals, only street
litter was extensively sampled and analyzed for its water pollution poten-

tial.

A significant aspect of the study was the calculation of street litter
accumulation rates for various land uses, This rate was found to range
from 0.5 to 8 1b/day/100 ft of curb, Average loadings varied from 2.4 1b/
day/100 ft of curb in single-family residential areas to 4,7 1b/day/100 ft

of curb in commercial areas,

Although the amount and composition of street litter was found to vary
with the day of the week, the season, land use, population density, and
pedestrian and vehicular traffic, the main component, by weight, was nearly
always the dust and dirt fraction (less than 1/8 in. in size), The total
dust and dirt fraction varied from 45 to 83 percent of the total litter,
The accumulation rate varied from 0.4 to 5.2 1b/day/100 ft of curb. The
accumulation rate by land use was as follows: single-family residential,
0.7 1lb/day/100 ft of curb; multiple-family residential, 2.3 1b/day/100 ft
of curb; and commercial areas, 3,3 1b/day/100 ft of curb,

The water pollution potential of the street litter was based on an analysis
of the soluble portion of the dust and dirt fraction. Approximately 3 per-
cent of the total dust and dirt was soluble. The weighted average amounts
of the constituent pollution parameters were as follows: 5 mg/g BOD, ,

40 mg/g COD, 0,48 mg/g total nitrogen, less than 0.05 mg/g phosphates,
more than 10 million/g total bacteria counts, more than 1 million/g coli-
forms, and 5400 mg/g fecal enterococci.

The most determinable measure-of pollution potential was deemed to be the
BOD, of the dust and dirt. Thus, based on a BOD, of 5 mg/g or 0,8 1b/day/
street mile, the average pollution potential of street litter was estimated

at 1 percent of raw sewage and 5 percent of secondary treatment effluent BOD;.


storm with a duration of 30 minutes from the fre-
quency curve given in Figure 4.

(2) Using the method of runoff coefficient, determine
the runoff rate resulting from the selected storm
event,

Example 5 demonstrates the selection of a storm event.

1-26


13,

14,

Edison Water Quality Laboratory, Environmental Impact of Highway Deicing,

Environmental Protection Agency, Water Quality Research, 11040 GKK (June
1971).

Burm, R. J,, D. F. Krawczyk, and G, L. Harlow, "Chemical and Physical
Comparison of Combined and Separate Sewer Discharges," Journal Water
Pollution Control Federation, Vol, 40, No. 1 (January 1968),



F = F.
inlets, t r,t + Pot
F F,
9 | FuytSe * Fate
5 = Se
nlets, t Pit + 2,¢
inlets, t = Ae t Mee
where F = flow in cubic feet per second
Q = pollutant concentration in milligrams per liters
L = pollutant load in pounds

However, the instantaneous flow entering inlets 1 and 2 at time t will
not arrive at point D at the same identical time. The flow entering
inlet 1 at time t will arrive at point D at a later time than the flow
entering inlet 2 at time t. This phenomenon is obvious since flow must
travel a greater distance from inlet 1 to D than from inlet 2 to D,
Therefore, a time correction factor is required to compensate for this

lag.

"Lag time" will be defined as the time of travel for stormwater to flow
from an inlet to the point of discharge. Lag time, At, is primarily a
function of the distance of travel and the diameter and slope of the

storm drainage pipe or channel, The. nomograph in Figure 18 can be used

to estimate lag time.

The nomograph in Figure 18 is based upon a typical storm drainage pipe

or channel fabricated from ordinary concrete, If the pipe or channel

is fabricated from another material, the estimated lag time derived from
the nomograph must be multiplied by an appropriate adjustment factor

from Table 10.

I-57


(6) Develop a corresponding pollutograph and loadograph
by using the appropriate procedure in conjunction with
the impervious area hydrograph and the street surface
hydrograph,

(7) Plot the impervious area hydrograph, pollutograph, and
loadograph upon the same coordinate system to produce
a quantity/quality hydrograph for the study area,

(8) Modify the total solids ordinates of the quantity/
quality hydrograph to reflect other quality parameters
of concern,
The procedure for a Level II assessment is demonstrated by Example 10,

Section II,

7.3 Level I11

A thorough level of assessment can be used to investigate a study area
consisting of two or more urban watersheds, portions of two or more
urban watersheds, or two or more homogeneous portions of an urban water-
shed, The study area is divided into two or more subareas, A quantity/
quality hydrograph is developed for each subarea, and subsequently, the
routing technique is used to develop a single composite quantity/quality
hydrograph representing the entire study area, The procedure is as fol-

lows:

(1) Divide the study area into subareas,

(2) Describe each subarea according to the following charac-
teristics: subarea size (acres), amount of interconnected
impervious area within subarea (acres), amount of street
surface area within subarea (acres), length of main drain~
age channel (feet), and slope of main drainage channel
(feet/feet).

(3) Determine an appropriate contaminant loading for street
surfaces within each subarea,

(4) Select a storm event according to the criteria presented

and compute the impervious runoff rate for each subarea.
The impervious runoff’ rate for each subarea will be

I-66


EPA-440/9-75-004

WATER QUALITY
MANAGEMENT PLANNING

FOR URBAN RUNOFF

D ST,
yet Arey

3

noua NZ
W agenct

P S
AL prote

U.S. ENVIRONMENTAL PROTECTION AGENCY
Washington, D.C. 20460


1200

1100:

1000

ly
SF pervious

drograph

to
off

Total

900

\
id

800

g

8

Hydrograph Que to |Stree

Q, Discharge in crs
a
°
So

400:

iN

300

\
7 surtade Rundff
NI

\
N

200

100

r—C>e_|

20

40 60 80 100

120

a

140 160 180 8 200

T, Time in Minutes

Figure 27, Unit Hydrographs Developed in Example 10,

I1I-23

220

240


Oe-v

cop oP «TROL NOD MARC CER

rrr csw tm M Ww ws ¢ R oS M LoD
cHtcace 13 5¢ so 12 286 2300030 fen
CHICAGE 13 50 98003 536 31800 18 a0
Tusa 200 5c +30 10100 1 1 ae 43000 1600 390
TULSA 20 50 151 19200 1 1 33 1 1800 1600
TULSA 20 sc tee “6600 1 2 25 267000 2500 4800 .
MED. IND» = @ 0 51 9100 1 268 60000 1400 ve 1600 32 248 87 23000 1400 420 35 28
HEAVY IND) = 6 G52 9800 $ 17000 1400 2 1600 4:7 3cy 150 S000 470 870 331
SAN JOSE T 8 4 53 7200 t 18 2 et 2:2 285 67 26000 3800 600 93 8
PHOENIX T= 8 1 St 17200 1 0 fe 8 2 130 4:7 256 38 24000 1200 3: 1 12
PILKAUKEF «= 12) 81 12000 1 2 0 8 8 5 6:3 175 120 22000 660 270 21 20
MILWAUKEE = «12 52. ‘goo 1 2 29 8 2 1500 3:6 128 170 15000 360 310 308
BUCYRUS 42 51 + "300 1 9 2 2 8 417 335 120 43000 780 620 35) BH at
BUCYRE: 12 82 S000 1 3 2 2 800 Sic 159 7 29000 260 470 6 «17 1c .
BALTINORE = «22 5. sio00 1 2 a 8 i 87 B18 290 210 25000 1800 680 12 33 M10 Bese
BALTineReE = 2 2S 21000 2 0 8 i t6 6:8 365 159 $3000 310 3600 14 38 300 este
SAN JOSE IT 8 2 81 7200 4 4 39 2 19 810 194 92 22000 1500 450 93 18 280 SeBES Gel
ATLANTA 2 2 52 3000 $ 2 10 1 150 G8 585 15¢ 72000 940 1100 84 3 880 1s4E5 503EE
ATUANTA 22 51 5000 i 3 2074 ik 275 38 18000 1800 280 12 1310
TutsA 22 51 3000 2 2 3 1 3 + 7h be 8100 65 180 26-77 :160 743E5 96 ES
PHOENIX 11 8 2 81 17200 1 i 6 2 18 +3 310 32 22000 1700 600 23 10 180 2e3ES 74262
Table A-10, LAND USE 50 - INDUSTRIAL
corre c sw mD AA 1 ar Ss ¢ A mS R 5S M LOAD BOS cOD POH TPOS Hos MHOC] CRUSE PBMC SRM CTOOLT. POULT
CINCINNATI = $330 3 20 «37 5600 2 4 2 467000 611000 $670 2720 $390 6670 2e8E6 SH2ES
CINCINNATI i 4 30° 9 80 437 5600 2 4 1 175009 $25000 5050 1810 4940 11880
1130 2 20 «37 S600 2 3 1 ‘56200 423000 1810, $920 1880 6920
12 30 9 20 137 S600 2 1 76000 400000 2640 1960 3280 8000
13 30 3 2 «37 S600 2 2 78900 526000 5790 3119 2630 10500
12 20 5600 4 48500 650 2620 650 595535,
13 20 4 980. 2770 800 730 «365,
1 4 20 5 * 21300, 20 21300 440
1 9 40 5600 . 087 16 310047 a 37
1 9 20 5600 * Oe 83 8 220017, + at
10 10 5600 ‘ O68 3 2600 15 6 2
10 30 9 20 037 S600 2 4 78000 488000 9850 a400 9250 L6E6 20685
10 10 9 20 137 300 2 ot 28: 5480 16000 12800 20568 86063
10 30 9 20 137 S600 2 4 1 32 109000 497000 4390 2300 3620 8800
19 20 » 170 23800 649 2810 “630 660450
1 3°30 20 7950 4 8 4 2 138 5080 2670038 480
1 3 39 20 zoo dS 42 326 4030 2880027 323
13 30 20 13500 2 4 127 66700 182 457
1 3 50 20 1114002 12 2 23000 30 431
1 3 20 10 goo |G ak a2 19 3 1300 20, 325
1 3 20 a5 1900 2 2 22 32 $190 S3ioo 70 523
13 20 £0 700 8 8 22 1a 50700 182 523
13 20 50 198003 3 32 188 280 29500 a 773
1 3 20 20 22 a2 8 6130063 377
13 20 5aso0 2 2 3 2 62 2900 32600 30 40s,
1 3 20 15 1a28 2 3 a2 tat 3e000 28 re
13 20 20 23 22 #320 4560073 670
13 20 50 19070033 32 188 2280 28600 20 361
13 20 20 3600} 2 7 2 49 3200 2480028 525
1 3 20 to 42004 2 72 20 72800 109 523
13 20 10 7: 22 a2 19803219028 ez
13 50 15 930003 536 i » “10
13 20 20 162000 2 3 7 2 (153 3220 34600 30 356
1 2 20 soro0 at 9 7 2 2700 4400 18000 100 20 530
1 2 20 4200 4 4 z 2 690 100 21000 180 a3 830
MILWAUKEE = «122 1so00 1 3 1 Oo 7 2 193
MILWAUKEE «1B ‘000 1 3 4 0 62 (93
mitnayKee = 3229 300 2 4 4 o 72 40
Huan $2 19000 1 2 4 9 9 2 770
MILWAUKEE 231 000 1 0 § 0 1 2 B60
MILWAUKEE «= 232 2oao9 2 2 4 o 72 30
MILWAUKEE «= 3251 12000 4 2 & 9 82 5
MILWAUKEE «= «252 go00 ig. 4 9 8 2 S500
BUCYRUS, 42 at 300 1 39 4 2 2 980
BUCYRUS. 12 23 300 2 0 2 2 208
sucyauS. 12 2 300 3 0 1 2 2 980
BUCYRUS, 12 st 300 2 9 i 2 2 890
12 82 sooo 1 9 & 2 2 800

Table A-11. CLIMATE 1 - NORTHEAST


2, Air Pollution Controls

Atmospheric dustfall can be a noticeable source of particulate contam—
inants that are washed off surfaces during rainfall events. Dustfall

results from the deposition of particulate matter from the atmosphere,

Some of this particulate material occurs naturally (fugitive dust from
soils and pollens) and is difficult if not impossible to control.

Other particulate material is caused by man-made processes. These in-
clude fugitive dust from disturbed soils (during and after construction)
and stockpiles; emissions from combusting materials, and emissions

from chemical reactions and grinding and pulverizing operations. Smoke,
made up of fine particles, is the most obvious particulate pollutant

associated with human activity.

Recent advances in stationary source controls for particulate matter

have resulted in removal efficiencies commonly greater than 99 percent.
Emissions from stationary sources are controlled by a large variety of
local, state, and federal agencies. These regulations are designed to
prohibit the accumulation of harmful concentrations and to prohibit

nuisance conditions, These particulate emissions can be controlled by
a variety of devices, including settling chambers, centrifugal separa-
tors, inertial separators, liquid scrubbers, filters, and electrostatic
precipitators, The applications of specific devices for specific emis-

sions are best determined by a case-by-case study
Particulate emissions from mobile sources are small per emission device;

but due to the large number of devices, their contribution can be severe.

Table 14 shows the breakdown of nationwide particulate emissions for 1970.

Iv-12


A comprehensive report evaluating the various approaches to control and
treatment of stormwater runoff is currently being prepared by Metcalf

and Eddy under an EPA contract,

v-15


Abstract

This manual provides technical assistance to state and local
water quality management planners to enable them to quantify
within reasonable limits the urban non-point water pollution
problem in a local planning area without extensive data gen-
eration, and to make a preliminary evaluation of cost effec-
tive abatement and control practices. The manual prescribes
procedures for several levels of input, each requiring more

self-generated data, with increasingly sophisticated results.

A state-of-the-art and an extensive bibliography on urban
storm water runoff is presented in the appendix. A glossary
is also included.

The manual is not intended to be used as a basis for abate-

ment design but does provide a guide to data generation for

this purpose,

iii


62-V

Table A-23.

THE BASIC STATISTICS OF THE AVAILABLE DATA,

RANGE (R), AND NUMBER OF SAMPLES (N) IN THE

INCLUDING THE MEAN (X), STANDARD DEVIATION (¢),
SET OF ALL DATA AND IN 19 SUBSETS OF THE DATA®

Me/euch wi/dey

Concenttations in Wicroprans per Gram of Dry Solide

cen? Toedton ee ee
10 i ot 20,300 171,000 1,700 16,000 - 7,230 0.6 3 7 2,600 as - 6 - 2
x - 18,200- 91,000 == = 700 - oe ee -
221300 252!000 aime .
® 1 2 2 »ooa a Pe er roa 1 1
» ry 14,000 62,000 850.«2,000 550 oto 1,t00 3.080.600 2A arma 50 LIES
° uss 11,900 61,800 © 90s 14080 a2 =k + 7,020 10D Sth aS
x e 2,100 28,2002 610 AK OTT
mm 431900 730%000 3,000 2,770 «3,600 7303100 8.032560 aloo 3,900 70010) 8eo. Scere Le
® 6 yo mw sm} so 8 & & 3S & © & oH
bt oF m 269,000 2,250 4,850 1,580 3,620 6,400 4.222533 23,309 KO? 20S
s . ” m20,000 2.70 = 1,280 1,MO 0,129,620 0200 ast
a x » 26,8002 ae 3236 1yBMO- 16008 B.S 695,000 190 Meg eke za
2 oe sito00 6,670 400 51390 alles 5330500 aztowo Peon” 170M? aoo LSE ES
= " as 6 1 m6 ny oy 7  e 7 » Ww we 9 2
oF ne 27,300 190,00 1473 -t=TD aon
. ow - - - = - + - 0 oon os
x f-15,000- 73,0002 toe = Abo ore ae ee or
1.050 Bleoo 1201000 2,300 iso nce ee moa
x ’ 2 ‘ oo - 2 ’ » 8
0 z 203 88,000 4,250, - 246 - 1,470 m8 107) -28,600 1,160 ‘70 vn a7
« m Poet a ey uo 57 16,700 855k kat
® re we tae Perene ae Ccm oe oo ST
2,300 a 1,000 SS 210. 72,000 3,500. 1,600 9377 a8
* p pe oe 3 woos Ss
1k a 29,100 159,000 993,390, 2,6k0 5D woes
° 383 46,300 195,000 1,900 1,390 1,000 1,820 Ae me uz Sayan ates
4 ase himp- 18,0002 ake Pe oer ony a ees ee a ae eee
1,300 175/000" 611000" 6,670 4400 5390 2,800 83s am 08S Soaks Tae
, 2 er er) wo pw oo» ow Boy os eon
af 10> 2,100 172,00 2,0 2370395 YL.aRs 7.088
. m 37,500 119,00 9 = een Amo MD 1S 6K.
. a tis0o- 20,000- ot oe ee nt eee
wo ay e530 si0000° —3!300 3 Seon 3.0 sth a0 3.700 1,100. 393,000 Scare Sans
oo x ne » ya 2 ve 8m 3 om wn
=
Se so rrr rrr irre ae) asm Me SST SESS
3 . 8 Pr ee, es ee) dao oe sk Saya ae
x + ee = os pee ee ee ee
ne ne 2.0 aie 88a nan Teo eho ey alate
, a oe , on Ron non RoR DR on
5k 0 10,000 38,000 : ” - 2,000 246 96 «4,500 2,600 ass S10 00 6.825 1.1EA
° 1” - - - - - 100 1om ast.
a ae - - 2 oe - - BI, 110 GS
% ioe 210 33.000 Slo aso awa” Olen
* 7 1 a 1 » oe 1 o 8 8 8 8? so 7 6



Appendix C
BIBLIOGRAPHY

ANALOG COMPUTER SIMULATION OF THE RUNOFF CHARACTERISTICS OF AN URBAN WATERSHED,

V.V.D. Narayana, J.P, Riley, and E.K, Israelsen, Utah Water Research Lab.,
1/69.

"Application of an electronic analog computer to the evaluation of the effects
of urbanization on the runoff characteristics of small watersheds," V.V. Dhruva
Narayana and J, Paul Riley, THE USE OF ANALOG AND DIGITAL COMPUTERS IN
HYDROLOGY, Proceedings of the Tucson Symposium, 1:38-48,

"an approach toward a physical interpretation of infiltration-capacity,”
Robert E. Horton, SOIL SCIENCE SOCIETY PROCEEDINGS, 5:399-417, 1940.

“Assessing the quality of urban drainage," Warren Viessman, Jr., PUBLIC WORKS,
10/69,

"How to determine average intensity of rainfall for use in the rational
formula," H.M. Gifft and George E, Symons, WATER AND WASTES ENGINEERING,
44-45, 12/68,

"The bacteriological aspects of stormwater pollution,” E.E. Geldreich, L.C.
Best, B.A, Kenner, and D.J. Van Donsel, JOURNAL WPCF, 40(11,1): 1861-1872,
11/68,

"Bacteriological comparison between combined and separate sewer discharges in
southeastern Michigan," R.J. Burm and R.D. Vaughan, JOURNAL WPCF, 38(3):
400-409, 3/66.

BANK AND SHORE PROTECTION IN CALIFORNIA HIGHWAY PRACTICE, California Div. of
Highways, 11/70.

THE BENEFICIAL USE OF STORM WATER, C.W, Mallory, Office of Research and
Monitoring, EPA, R2-73-139, 1/73.

BIBLIOGRAPHY OF R & M RESEARCH REPORTS, Office of Research and Monitoring,
EPA, R5-73-012, 1/73.

Biospherics Incorporated proposal.

"Calculation of water pollution by surface runoff," N.A. Pravoshinsky and
P.D, Gatillo, WATER RESEARCH, 2(1):24-26, 1/68.

CHARACTER AND SIGNIFICANCE OF HIGHWAY RUNOFF WATERS, A PRELIMINARY APPRAISAL,
Robert 0, Sylvester and Foppe B, DeWalle, Washington State Highway Commission,
12/29/72,


1000

900
800 i _—pamerious durtncel indropsect

700 ig
& 600-4 |
\
§ 500
&
‘ 400 | | ww Street rface |Hydrograph
IN

“LT ‘SS
| NSN

100-

———o
20 40 ‘60 80 100 120 140 160 180 200 220
T, Time in Minutes

240

Figure 28, Hydrographs Developed in Example 10

11-24


INL

Table 5, NINETY-FIVE PERCENT CONFIDENCE LEVEL

1bs/curd xo. ‘gran
mi/day Concentrations in micrograns per gram of dry solid ms
Category Loading a a a a Cr OPO, TPO, NO, NH, OrgN Cdr SE ea on reon
Land Use 20 Open space
20 Residential 82,000, 1,800,
30 Commercial 74, 88,700, 6,430, 3,400,
40 Light industry
50 Heavy industry 8.255,
Climate 1 Northeast 139, 870, a, 260, 4.488,
2 Southeast 2,240, a1, 7,084,
4. Southwest 50, 470, 78, 57, 15,
5 Northwest 30, 34,500, 10, 480, 6.855, 1.184,
Average Daily =< 500 252,
Traffic
wo. day 500 - 5,000 9,500, 1,080, ly 3.485,
5,000 - 15,000
> 18,000 2.855,

‘Type of Land- 1 Graze 8.3E5, 7. 4E4,
scoping 2 Trees 43, rien ‘
Beyond the » ARTy
Sidewalk, ‘3 Landscaped

buildings
4 Hard surfaces 401, 16, 7.1ES
Street Surface 1 Asphalt 2,470, 1,770,
Material a * 2,600, 680"
ron 3 Concrete 38, 72,000, 3,520, 600, +680,
ALL date 156, 19,900, 140,000, 1,280, 2,930, 804, 2,640, 2,950, 3.4, 212, 104, 22,000, 1,810, 418, 25, 21, 370, 1. 7ES,,

“only those subset means are shown which differ from the aeans of the set of all data et the 95-percent confidence level (Student t > 2,25, Degrees of Freedom > 10). Total

umber of permitted substitutions = 47,

.
‘Coliform counts are expressed in computer notation, 1.0., ES = 10°.

Percent Standard Error of the Mean Subscripting Code:

220-9, b= 10-19, c= 20 - 2, d= 30 -

39, © = 40 ~ 49, f = 50 - 62,


"Chapt. VIIIC. Control of sediment in the urban environment," Harold P.
Guy, TREATISE ON URBAN WATER SYSTEMS, Colorado State U., 7/71.

“Deep tunnel storage may solve city storm water problem," ENVIRONMENTAL
SCIENCE AND TECHNOLOGY, 3(3):209-211, 3/69,

"Development of a simulation model for stormwater management," J,A. Lager,
R.P. Shubinski, and L.W. Russell, JOURNAL WPCF, 43(12):2424-2435, 12/71.

"Discharge from separate storm sewers and combined sewers," W.J. Benzie and
R,J. Courchaine, JOURNAL WPCF, 38(3):410-421, 3/66.

“Drainage of airport surfaces - some basic design considerations," Stifel W.
Jens, ASCE TRANSACTIONS, Paper No. 2348,

"Drainage of roads and paved surfaces," M.J, Hamlin and F,D, Hobbs, INSTITUTE
OF PUBLIC HEALTH ENGINEERS, 69(2):122-141,

"Dustfall as a source of water quality impairment," R.E. Johnson, A.T.
Rossano, Jr., and R.O. Sylvester, JOURNAL SANITARY ENGINEERING DIVISION,
ASCE, SA1:245, 2/66,

EFFECT OF URBAN GROWTH ON SEDIMENT DISCHARGE, NORTHWEST BRANCH ANACOSTIA
RIVER BASIN, MARYLAND, F.J. Keller, U.S.G.S. Prof. Paper, 450-C, C129-131,

"Effect of urbanization on storm water peak flows," Pedro C.C. Da Costa,
JOURNAL SANITARY ENGINEERING DIVISION, ASCE, SA2:187, 4/70.

EFFECTS OF DEICING SALTS ON WATER QUALITY AND BIOTA; Literature review and
recommended research, R.E. Hanes, L,W., Zelazny, and R,E, Blaser, National
Cooperative Highway Research Program Report 91, 1970.

"Effects of urbanization on storm water runoff quality: A limited experiment,
Naismith Ditch, Lawrence, Kansas," E.E, Angino, L.M, Magnuson, and G.F,
Stewart, WATER RESOURCES RESEARCH, 8(1):135, 2/72.

THE EFFECTS OF URBANIZATION ON UNIT HYDROGRAPHS FOR SMALL WATERSHEDS, HOUSTON,
TEXAS, 1964-67, W.H. Espey, Jr., and D,E, Winslow, Office of Water Resources
Research. (Also APPENDICES - DATA COMPILATION)

"The effects of urbanization on water quality," E.C. McGriff, Jr., J. ENVIRON.
QUALITY, 1(1):86-88, 1972,

"Elemental composition of suspended particulate matter in metropolitan New
York," Norman L. Morrow and Richard S, Brief, ENVIRONMENTAL SCIENCE AND
TECHNOLOGY, 5(9):786-789, °9/71.

ENGINEERING INVESTIGATION OF SEWER OVERFLOW PROBLEM; A Detailed investigation
into the cause and effect of sanitary sewer overflows and recommended
remedial measures for Roanoke, Virginia, Hayes, Seay, Mattern & Mattern for
FWQA, 5/70.

C-3


EXAMPLE 2

Predict the load per acre five days after a rain and the composition
of solids present on an asphalt street in a new residential area in

Portland, Oregon, where the average daily traffic is less than 500,

Solution: Following the procedure given, the solution is obtained in

these steps:

1. Use only substitutions at the 95 percent confidence
level shown in Table 5.

2. Present a range of possible data based on the loading
rate only:
a. The area selected is residential. Move upward to

the residential land use category. No loading
substitution is permissible, One could substitute
other compositional parameters but we are looking
for a row that has a permissible loading substitu-
tion,

b. Portland is in the northwest, Move upward to
the northwest climate category. A loading sub-
stitution is permitted. After making all per-.
missible substitutions into the row labeled
"All Data," the new row is shown in Table 11.

3. Since there are no other permissible substitutions of
the loading rate available under any other category
by which the site may be classified, present two
tables: the means of the set of all data with no
substitutions and Table 11.

4, The loading rate in Table 11 is lower than the mean of
all data and probably better represents the real situa-
tion in Portland, Oregon. For all later calculations,
use Table 11.

5. Convert the loading rate to load per curb mile as
follows:
30 1b/curb mi/day x 5 days = 150 1b/curb mi

II-4


4. Conclusions Obtained in the Data Processing

Table A-24 provides the mechanism for detecting significant functional
relationships between independent and dependent parameters. Some of
these relationships observed by the authors are put forward here, It
should be realized that these conclusions are derived from data which
represent the combined effects of natural physical processes and man's
activities, Sweeping the streets, for example, logically reduces the
apparent loading rate recorded here but does not change the rate of the
natural accumulating process, a parameter which cannot be measured by
the methods used in this study. These conclusions represent the state
of the nation resulting from normal mean living conditions. Unexpected

findings are noted with an asterisk (*),

a, Loading Rates Are Lowest in:

1. Commercial areas, probably because they are swept frequently
2, Northwest

3. Areas with highest traffic, probably because the removal pro-

cesses (primarily traffic generated winds) are more active

*4, Tree covered areas; unexpected because it was thought that

leaves contributed substantially to loading rates
5. Concrete surfaces

b. BOD, Concentrations Are Lowest in:

1, Residential and heavy industrial areas

2. The southwest, probably reflecting the lack of lush vegetation

relative to the East Coast
3. Areas with moderate ADT

4, Areas with landscaped buildings, probably reflecting better

maintenance

5, On asphalt road surfaces

A-37


Section I
REFERENCES

Chow, Ven Te, Handbook ‘of Applied Hydraulics, 1964.

Espey, W.H. and D.E, Winslow, The Effects of Urbanization on Unit
Hydrographs for Small Watersheds, 1968.

Metcalf and Eddy, Inc,, Storm Water Management Model, Vols. I-IV,
EPA, July 1971 ~ October 1971,

Sartor, J.D. and G,B, Boyd, Water Pollution Aspects of Street
Surface Contaminants, EPA, Research and Monitoring, Envir,
Protection Tech. Series, EPA - R2-72-081, Nov. 1972.

1-68


the plasticity of data on the characteristics of runoff from pervious
areas required that at this time the manual be limited to the character-
ization of runoff from street surfaces only. The basic model was modi-
fied for this purpose rather than adapting a more limited street runoff
model, It is planned that as information becomes available, the manual
could be expanded to include a characterization and quantification of

runoff from the entire urban area.

Preliminary data have demonstrated that impervious surface contaminants
are, by far, the predominant pollutants associated with urban storm wa~
ter runoff. It should be noted that street surfaces serve as a vehicle
for transporting other sources of runoff to a storm drain, Contaminants
which originate from other sources often come to reside and accumulate
upon street surfaces by (1) wind actions which blow contaminants onto
street, (2) the evaporation of lawn irrigation runoff upon street sur-
faces, and (3) the evaporation of residual non-street storm water runoff
upon street surfaces, (This last factor is perhaps the most important
since a certain time of travel is required for non-street contaminants
to reach street surfaces, Often, a storm event will cease after non-
street contaminants have reached a street surface but before reaching a
storm drain and consequently non-street contaminants may eventually come
to reside upon a street surface either by deposition or evaporation.)
Therefore, contaminant loadings found upon street surfaces include non-

street contaminants.


Appendix B

SAMPLING PROCEDURE


se-I

100

Wy75 (mtn. )

e 7 esh

VA
Figure 11. Determination of Ws

10.0


climate, season, and type of landscaping in the area beyond the side-
walk, Average daily traffic (ADT) was determined from traffice maps
obtained from the traffic engineer's office of the city of interest.
Occasionally, if these parameters were not explicitly stated in the
publication, they were obtained from a picture of the area or from a

verbal description given over the telephone by the city engineer.

In those areas where the study was conducted on a whole watershed, the
ADT was calculated by a circuitous method described as follows, A unit
area was selected for the given city. It was then assumed that people
enter and leave the area ultimately by majar arteries and that one ar-
rival or one departure constituted one ADT unit, The total traffic

into and out of the area was determined and expressed as ADT per acre
of area. Finally, ADT was expressed as number per day per curb mile

of road by dividing the ADT per acre by the highway density in curb
miles per acre, This unit is different from the regular ADT; but the
unit length, the curb mile, is a standard unit used in the daily loading
values and was believed to be acceptable for categorizing a given water-
shed area as lightly or heavily traveled. These values are recorded

without distinguishing marks in the data matrix.

To facilitate the operation of reading the data into the computer, the
total coliform (TCOLI) and fecal coliform (FCOLI) numbers were repre->
sented with the exponential notation, e.g., 2.0 E6 is equivalent to 2,0
x 108,

Chlorinated hydrocarbon and mercury analyses were available only in the
URS I study. Since they were so few in number, these data were separated
out of the data matrix and treated individually. All of the data avail-
able except the chlorinated hydrocarbon and mercury analyses are shown

in Table A-4, The chlorinated hydrocarbon and mercury concentration
data are given in Table A-5 along with the basic statistics of these data

sets.


EXAMPLE 7

Using the hydrograph developed in Example 6 (Figure 22), develop a
corresponding pollutograph and loadograph based on a contaminant load-
ing of 500 1b/curb mile, if the length of all streets in the study area
is 30 miles.

The general pollutograph equation is:

AP = (4.6 "ave Py) At
where AP = Amount of pollutants removed during the time interval, At
Po = Amount of pollutants remaining at the beginning of the
time interval, At
Tave = Average runoff rate within the time interval, At
Curb mile = 30 X2 = 60, PS (initial pollutant load) = 500 X 60
= 30,000 lbs.

Values of total solids concentration and accumulative solids load are
plotted against time, and the resultant pollutograph and loadograph are

shown in Figure 23.

II-11


€e-V

om

chm mw we me cm vs
gigas 4g aes go ay dg ea ae #2088 *2gQ99 TL Bese eae oom em ms

20 240 2 re
SAN JOSE T 4 4 23 300 i 1 a 12 2 @ 32 21000 2100 380 100
ATLANTA 22 21 goo toda 214 1 295 150 24000 280 210 9 3
ATLANTA 2 2 22 300 2 Fa 244 31 .
ATLANTA 22 23 300 do dod 2 21 1 165 7o 13000 480 280 7
ATLANTA, 22 2 300 1 3 1 2 28 1

Table A-15, AVERAGE DAILY TRAFFIC - LESS THAN 500

cm cos w mow mw mts cA mR Sm Wao mos cao one OL mm mmm TO ont
‘OURHAM 2 0 20 %7 10 429 2900 1 4 4 +20 400 © 5300 65500 212 417 sates
DURHAM 2 0 20 1065 10 «34 4200 2 4 2 +24 600 137
CHICAGS 1 2 20 15 1900 22 302 32 S400 5310070 523
CHICAGS 1 3 20 18 1828 23 32 122 2030 © 34000 24 B45
CHICAGE 1 30 20 20 3600 te 72 yo 3240 24500 ee S25
TULSA 2 0 20 95 50 +41 3200 32 33° 25000 207000 1500 1200
BALTIMORE 22 23 yoo 2 i fb 26 13 1 67 641 290 120 24000 1000 430 55 23 760 1408S
BALTIMERE 2 2 24 700 4 Of 2 5 4 33 545 120 120 18000 730 150 2 5 730
TULSA 22 23 700 2 2 1 3 . 6 143° 150 71 17000 970 520 1 110 180 &

Table A-16, AVERAGE DAILY TRAFFIC ~ 500 to 5000


2, Data Transformation and Augmentation

There were 14 independent and 27 dependent parameters recorded in the
data matrix, These parameters are described in Table A=l. The depen-
dent parameters were expressed by a variety of units in the literature
examined, These were transformed into units of parts per million (ppm)
of total solids for inclusion in the matrix. Therefore, the concentra~
tions are directly related to loading rates, that is, ppm of solids on
the street as expressed in any units desired (e.g., micropounds per
pound or micrograms per gram of dry solid). Loading rates were re~
corded in the literature by several units also, These were transformed
to pounds per curb mile per day. For most of the data, this transfor-
mation involved no guesswork,or indefensible assumptions, However,
whenever loading rates were recorded in the literature as pounds per
acre of watershed per time unit, it was necessary to assume that only
street runoff contributed to this solids load because there was no way
to estimate the contribution from soil erosion. This latter contri-
bution is expected to be small except where active construction work
is in progress. Daily loadings on a per curb mile basis were obtained
by dividing the loading per acre by the curb miles per acre in the water-
shed, The latter figure, fortunately, was usually available in the
publication, This type of transformation was necessary for data from

the Tulsa Study and a few other ‘smaller studies.

Very few of the literature sources provided an adequate cataloging of

the independent parameters. Population density, fraction of the area
covered by impervious material, average age of the structures in the
area, and the fraction of the area as road surface were not available
from enough sources to make them generally useful parameters, Data on
the condition of the street, the street surface material, cléaning
method, and days since the street was last swept or rain had fallen were
generally available only from the URS Research studies. These parameters
were used for separate analyses described later, Those parameters that

were consistently available in the literature sources were land use,

A-8


Table 10. LAG TIME ADJUSTMENT FACTORS

CHANNEL MATERIAL ADJUSTMENT FACTOR
Plastic, glass, drawn tubing 0.69
Neat cement, smooth metal 0.77
Planed timber, asbestos pipe 0.85
Wrought iron, welded steel, canvas 0.92
Ordinary concrete, asphalted cast iron 1.0
Unplaned timber, vitrified clay 1,07
Cast-iron pipe 1.15
Riveted steel, brick 1,23
Rubble masonry 1.30
Smooth earth 1.38
Firm gravel 1.54
Corrugated metal pipe 1.69
Natural channels in good condition 1,92
Natural channels with stones and weeds 2.69
Very poor natural channels 4,62

Applying the concept of lag time to the hypothetical study area:

At

1 lag time from inlet 1 to D

Wl

At lag time from inlet 2 to D

tl

2

Accordingly, the accumulative flow and quality of runoff at time t at the
point of discharge D can be expressed by:

FL, = F + F
D,t Lt - bt, 2,t = dt,
(F. 7 Qe 2+ Foy, la? ¢ _ Mt
ee: at At? “Saye ~ de, 2,t - dt, %t ty
t (F. ,+ Fo, ome?
, 1,t Mt, 2,t tt.
= L + 1,
Int 1,t = bt, 2,t - bt,

1-59


SELECTED URBAN STORM WATER RUNOFF ABSTRACTS, Franklin Institute Research Labs
for FWPCA, 6/69.

SELECTED URBAN STORM WATER RUNOFF ABSTRACTS, Franklin Institute Research Labs
for Water Quality Office, EPA, 11024 EJC, 7/70.

SELECTED URBAN STORM WATER RUNOFF ABSTRACTS, July 1970 - June 1971, Franklin
Institute Research Labs for Water Quality Research, EPA, 11024 FJE, 7/71.

SELECTED URBAN STORM WATER RUNOFF ABSTRACTS, July 1971 - June 1972, Mrs,
Dorothy A, Sandoski for Office of Research and Monitoring, EPA, R2-72-127,
12/72,

SIMPLIFICATION OF INTEGRATED STORMWATER PLANNING FOR MODERN MULTIPLE LAND
USE IN URBAN AND SUBURBAN DEVELOPMENTS, Brian M. Reich, Unpub, Research
Project Tech, Completion Rept., Pennsylvania State U., Institute for Research
on Land and Water Resources, 3/31/70.

"Simulation of runoff from urban watersheds," V.V. Dhruva Narayana, J. Paul
Riley, and Eugene K, Israelson, WATER RESOURCES BULLETIN, 7(1):54, 2/71.

SIMULATION OF WATER QUALITY IN STREAMS AND CANALS; Program documentation and
users manual, Texas Water Development Board, 9/70,

"Some effects of urbanization on runoff as evaluated by Thornthwaite Water
Balance Models," Robert A, Muller, PROCEEDINGS 3RD ANNUAL AMERICAN WATER
RESOURCES CONFERENCE, Urbana, Illinois, 11/67.

"Source control of urban water pollution," James P, Heaney and Richard H,
Sullivan, JOURNAL WPCF, 43(4):571-579, 4/71.

“Spatially variable discharge over a sloping plane," G.H, Keulegan,
TRANSACTIONS, AMERICAN GEOPHYSICAL UNION, 956-968.

"Stilling pond storm overflow studies," Y.R, Reddy and John Pickford,
JOURNAL SANITARY ENGINEERING DIVISION, ASCE, SA4:609, 8/72,

STORAGE AND TREATMENT OF COMBINED SEWER OVERFLOWS, Office of Research and
Monitoring, EPA, R2-72-070, 10/72,

STORM AND COMBINED SEWER DEMONSTRATION PROJECTS, January 1970, William A,
Rosenkranz, Div. of Applied Science and Technology, FWPCA, 1/70.

STORM AND COMBINED SEWER POLLUTION SOURCES AND ABATEMENT, ATLANTA, GEORGIA,
Black, Crow and Eidsness, Inc, for Water Quality Office, EPA, 11024 ELB,
1/71,

"Storm sewer design by the inlet method," Albert B, Kaltenbach, PUBLIC WORKS,”
86, 1/63,


The characteristics of the selected storm event (i.e,, its duration,
average intensity, and frequency of occurrence) will greatly influence
the results of one’s assessment, ‘Therefore, the following material is

presented as general guidance for selecting a storm event,

e Basic Considerations, The pollution potential of urban runoff is
influenced by both its quantity and quality. In certain situations, a
large volume of moderately polluted runoff may contribute a greater pol-
lutant load to a receiving water than a smaller volume of highly pollu-
ted runoff even though the pollutant concentration is considerably
greater within the smaller volume. Consequently, this raises the ques-~
tion as to which is more significant with regard to receiving waters;

pollutant concentration or pollutant load?

Generally, the assimilative characteristics of a receiving water will
determine which is more significant, Certain receiving waters are
more capable of assimilating a large volume of moderately polluted run-
off while others are more capable of assimilating a small volume of

highly polluted water.

The percentages of contaminants removed from street surfaces by var-
ious combinations of runoff rate and runoff duration are given in Table
9, Examination of the values within the table reveals that contaminant
removal is a direct function of the total inches of runoff. Consequent-
ly, a runoff rate of 0.5 inches per hour which lasts for 1 hour will re-
move the same percentage of contaminants as a runoff rate of 1.0 inches
per hour which lasts for 0,5 hours since, in both cases, 0.5 inches of

total runoff occurs.

Figure 2 describes street surface contaminant removal as a function of
total inches of runoff. The shape of the curve indicates that, as con
taminant removal increases, the total inches of runoff increases expo-
nentially. Therefore, Figure 2 reveals that ‘contaminants become in-

creasingly more difficult to remove (i.e., require increasingly more

I-20


6I-V

on

cop rok mes mS mA omc Rm

csw mm Ss cA ms 2 5 x wD mS
einctnvatt 1 3 30-3 20 «37 214 167000 611000 $670 2720 5390 6670

1% 30 8 20 437 231 178900 328000 5050 1810 S580 13880

if 3g 3 i eid ‘$4200 423000 isto 1920 isso $920

$230 9 20 137 2a4 76000 So0000 2680 1960 3280 8000,

43300 9 20 137 244 74300 S26000 5790 3110 2630 10500,

12 30 69 20 t37 204 ‘75000 889000 48804800 3250,

232 4 ef a7 020

3 30 + 487000 230 350

49 30 9 20 «37 aad 32 103000 497000 4330 2300 3620 8800

13 30 20 +4 334 S050 2670038 ‘80

13 30 20 is 4 2 ¥6 4090 2880027 323

1330 20 zs 1 2 7h 14800 66700 142 457

20 30 s0 “5 oss 21 3 +20 86 25300 163000 3200

200 30 3 20 178 23 2 +81 ¥1 25300 287000 1600

60 3 +4 23 x $00

6 0 32 to 322 8600 21000 1000 600

rarer 124 13 2 2

S43 tia ie 2 3

pares 124 012 26

rarer pis i132 83

123 fos 0 4 2 260

12 32 224 0 72 30

22 3 tos e 11 5

22 32 103 aoe if

S23 rey 3 2 20

: bis 89 3

22% pid 211 668

22 32 fos 28 tats

22 3 124 3 1 20 S6ES

22 32 224 3 1 oan

ox 1,24 60 2 4 FD Iay

42 38 tig oo 2 3 25 400 sezee
SEATILE 3331 124 1e 1 46 15 S00 14668
SEATIE 53 38 ted 12 i 16 © 390 teaes

\
Table A-8, LAND USE 30 - COMMERCIAL

am © Sw om sk fo mT S$ CoA MS RS MH WAD RODS OD. OFOK TROL HOS MELO] REESE. FeO.
GRAND RAPIDS 1 0 40 5600 5 m7 9 16 310047 a 7
Tuscon 4 3 40 12000 ‘ 201000 240 430 1+087 14086
quscsn ed 40 12000 . 224000 760 750 30367 4685
TULSA 20 40 000 10 «46 24 1 oe 57 39600 222000 2700 1300 2686 5.082
LIGHT iyo, & 8 40 g300 ts 986 18000 73000 1400 ve 1690 444 288 130 22000 2800 490 44 24 400 34768 61SES
SAN"Jese 18 40 7250 1 2 4 1302 13h 4 300 47 24000 2000 $00 119 9 350
PHOENIX T= & 40 12300 1 4 fe 10 20M 44 208 toe 20000 2500 430 15 230
BALTINgRE = 2-240 $900 1 2 4 26 1 8 +b 760 280 31000 5999 830 37 34 780
SAN JOSE IT 2 40 750 i 2 4 5 2208 347 306 71 17000 2700 430 120 13 340 sees Ge7EL
ATLANTA 22 40 so00 i 2 i 2 30 1 1850 1:5 462 140 16000 “780 300 1396 «320 a 3E8
yucsa 2 2 40 700 2 3 i 5 i “tee 28 138 110 35000 1100 440 24 93 360 te
PHOENIX 11 4 2 40 12300 1 i 8 so 2 8 31 188 120 28000 2100 460 18 15 360 16368 BeREL
SEATTLE $3 80 tooo 2 2 ¢ 1 1 39 iss 239 110 27000 1100 490 20 16 480 3+1E6 9e1E3

Table A-9, LAND USE 40 - LIGHT INDUSTRY


"A systems study of storm runoff problems in a new town,” Charles W. Mallory
and John J, Boland, WATER RESOURCES BULLETIN, 6(6):980, 11-12/70.

THESAURUS OF WATER RESOURCES TERMS; A collection of water resources and
related terms for use in indexing technical information, U.S. Bureau of
Reclamation, 1971,

TOXIC MATERIALS ANALYSIS OF STREET SURFACE CONTAMINANTS, Robert E. Pitt and
“Gary Amy, URS Research Company for Municipal Pollution Control Branch,
EPA, 1/73.

"Treatment of urban runoff," F, Condon, APWA REPORTER, 40(3):8-11, 3/73.

"Treatment of urban stormwater runoff," F,L, Evans, III, E.E, Geldreich,
S.R. Weibel, and G,G. Robeck, JOURNAL WPCF, 40(5,2):R162-R170, 5/68,

UNDERWATER STORAGE OF COMBINED SEWER OVERFLOWS, Karl R. Rohrer Associates,
Inc. for EPA, 11022 ECV, 9/71.

“Urban effects on quality of streamflow," E. Gus Fruh, EFFECTS OF WATERSHED
CHANGES ON STREAMFLOW, WATER RESOURCES SYMPOSIUM NO, 2, Texas, 10/68,

URBAN GROWTH AND THE WATER REGIMEN, John Savini and J.C. Kammerer, Geological
Survey Water-Supply Paper 1591~-A, 1961.

“Urban hydrology,” W.J. Bauer, THE PROGRESS OF HYDROLOGY, Vol. 2, Illinois
University, 7/69,

"Urbanization and the water balance," Andrew M. Spieker, PROCEEDINGS OF THE
SYMPOSIUM ON WATER BALANCE IN NORTH AMERICA, Banff, Alberta, Canada,
American Water Resources Association, 6/69.

URBAN DRAINAGE PRACTICES, PROCEDURES, AND NEEDS, Herbert G, Poertner, Robert
L. Anderson, and Dr. Karl W. Wolf, American Public Works Association, 12/66,

"Urban land runoff as a factor in stream pollution," S.R. Weibel, R.J.
Anderson, and R.L. Woodward, JOURNAL WPCF, 36(7):914-924, 7/64,

URBAN RUNOFF, M.B. McPherson, ASCE Urban Water Resources Research Program
Tech, Mem, No, 18, 8/72,

"Urban runoff adds to water pollution," ENVIRONMENTAL SCIENCE AND TECHNOLOGY,
3(6):527, 6/69,

"Urban runoff by road research laboratory method," Michael L, ‘Terstriep and
John B, Stall, JOURNAL HYDRAULICS DIVISION, HY6:1809, 11/69,

c-10


A summary of these parameters is shown on a typical hydrograph in Figure 6,
The statistical work by Espey produced the following equations which repre-
sent the 30-minute unit hydrograph for an urban watershed:

- -0,490
0.315 -0,0488,-0.49

tT = W.1at
Q = 3,84 x 10% 7,727 cayeao)

T, = 3.67 x 10° (4/640) 2+ 14Q72-15
Weg = 4-14 x 10* (a/640)2-03q72- 04
Wy, = 134 x 10° (4/640)°* 92q70- 4

where A is the size of the study area or subarea in acres,
Lis the length of the main drainage channel in feet, *
S is the slope of the main drainage channel in feet/feet,

I is the percent of impervious cover for the study area or subarea.

Espey's equations can be solved directly or with the assistance of
Figure 7, which is used in conjunction with Figures 8 through ll.
Figure 7 is first used to estimate a value of Q/A. In turn, the esti-
mated value of Q/A is used in Figures 8 through 11 to predict values

of Ty Ty Weg? and Ws) respectively.

* If actual value of main drainage channel is available, it should be
used in place of approximation shown in Figure 5. If drainage mainly
takes place along street gutters in the absence of a well-defined
channel, then L should be taken to be equal to the sum of two sides
of the rectangular urban area shown in Figure 5.

1-32


results, the continued intensive use of deicing salts will continue to cause

severe plant injuries and additive water pollution effects.

Many techniques and measures can be adapted to each specific locale which can
alleviate some of these problems, especially in the area of salt storage

depots, Because this problem is beyond the scope of this study, we recommend
that the reader consult the EPA study on the "Environmental Impact of Highway

Deicing"> to obtain the necessary information,

III-3


LE-1

1,000

Ws0 (min.)

Tae st

10
01

Figure 10,

VA

Determination of W

10.0


5, Summary

The URS staff has assembled all presently available data on the rates of
accumulation of solids and the concentrations of various constituents in
those solids that collect on street surfaces, These data have been
grouped and processed into a form which should be useful to an urban
planner in predicting the pollutional load from areas projected for ur-

ban development.

The range and scatter in the available data are extreme. Both the
sampling variability and the complexity of natural systems contribute
to this extreme variance, Attempts to test conceptual models with the
available data have met with absolutely no success because the models
are much too simple to adequately describe the conditions in the real
world, The available data records are not sufficiently complete to per~

mit sophisticated analyses of covariance.

The data and calculations presented here represent the state-of-the-art,
as viewed by the participants in this study, on the subject of loading
rates and chemical composition of solids on streets. The results pre-
sented here are probably adequate for most urban planning operations,

As the nation becomes more concerned in the future over nonpoint sources
of pollutants, more sophisticated models of accumulation rates should be
developed and tested. The methods of sample collection and analysis
should be standardized. Controlled experiments should be carried out in
an effort to identify sources of solids loading. These adjustments in
the state-of-the-art will permit refinements in the methods of handling

data as presented here,

A-42


The flow rate and runoff influent into treatment facilities can be in-
directly controlled by controlling the flow rate entering the city's
storm drainage system, An example of this approach to runoff control

is given below.

h. Rooftop Ponding - In an 80-acre urban renewal project in downtown
Denver, rooftops were constructed to hold up to 3 inches of rainwater.
This water was retained then released as surface runoff at a controlled
rate. Other rooftop storage schemes use the intercepted rainwater to

supplement the water requirements of an industrial complex,

2, Physical Treatment

Various methods of physical treatment are presently available that can
effectively be used for the removal of suspended solids from stormwater
runoff, but at the present time, physical treatment is generally less
effective in the removal of organics and nutrients than biological or

physical-chemical treatment,

The major advantage of physical treatment processes is their adapability
to automated controls and the rapid startup and shutdown that is often
required in runoff treatment, Recent improvements in physical treatment
processes have resulted in more rapid removal of suspended solids and

more effective removal of organics.

In addition to the conventional physical treatment processes used in
wastewater treatment (i.e,, sedimentation; flotation; screening, and
filtration), more recent physical treatment processes have been de-
veloped that promise to be well suited for stormwater runoff treatment,
These techniques include dissolved air flotation, ultrahigh rate fil-

tration, swirl concentration, and a variety of screening techniques,

Iv-19


Cubic Feet per Second

Figure 6,

ur)

TIME

Definition of Unit Hydrograph Properties

1-33



HYDROGRAPH SYNTHESIS FOR WATERSHED SUBZONES FROM MEASURED URBAN PARAMETERS,
J.B. Evelyn, V.V.D. Narayana, J.P, Riley, and E.K, Israelsen, Utah State
U., 8/70,

HYDROLOGIC DESIGN, Chapt. G200 - 1969 edition, Storm Drain Design Manual,
City of Los Angeles Bureau of Engineering, 1970,

HYDROLOGIC EFFECTS FROM URBANIZATION OF FORESTED WATERSHEDS IN THE NORTHEAST,
Howard W. Lull and William E. Sopper, U.S.D.A. Forest Service Res. Paper
NE-146, 1969,

HYDROLOGIC EFFECTS OF SUBURBAN DEVELOPMENT NEAR PALO ALTO, CALIFORNIA,
J.R. Crippen and A.O, Waananen, U.S.G.S. Water Resources Div., 1/69,

HYDROLOGY FOR URBAN LAND PLANNING - A GUIDEBOOK ON THE HYDROLOGIC EFFECTS
OF URBAN LAND USE, Luna B. Leopold, U.S.G.S, Circular 554, 1968,

"The hydrology of urban runoff," A.L, Tholin and Clint J. Keifer, JOURNAL
SANITARY ENGINEERING DIVISION, ASCE, SA2:47, 3/59,

A HYDROMETEOROLOGICAL STUDY RELATED TO THE DISTRIBUTION OF PRECIPITATION
AND RUNOFF OVER SMALL DRAINAGE BASINS - URBAN VERSUS RURAL AREAS, R.G.
Feddes, R.A, Clark, and R.C, Runnels, Texas A and M U., Tech, Rept. No. 28,
6/70.

HYPOCHLORITE GENERATOR FOR TREATMENT OF COMBINED SEWER OVERFLOWS, Ionics,
Inc. for Office of Research and Monitoring, EPA, 11023 DAA, 3/72,

"The influence on flood peak discharges of some meteorological, topographical,
and hydraulic factors," Peter 0. Wolf, International Assoc. of Scientific
Hydrology, General Assembly of Toronto, Tome III:26-39, 1958,

INVESTIGATIONS OF POROUS PAVEMENTS FOR URBAN RUNOFF CONTROL, Franklin Institute
Research Labs for Office of Research and Monitoring, EPA, 11034 DUY, 3/72.

“Lead in a suburban environment," P.R. Atkins, JOURNAL OF THE AIR POLLUTION
CONTROL ASSOCIATION, 19(8):591-594, 8/69,

"The measurement of the effects of building construction on drainage basin
dynamics," D,E. Walling and K.J. Gregory, JOURNAL OF HYDROLOGY, 11:129-144,
1970,

"Mercury and other metals in urban soils," David H. Klein, ENVIRONMENTAL
SCIENCE AND TECHNOLOGY, 6(6):560-562, 6/72.

"A method of computing urban runoff," W.I, Hicks, Esq., ASCE TRANSACTIONS,
Paper No. 2230.

c-5


Special sample preparation should be used for the heavy metal analysis
of the liquid samples, All liquid samples can be cotton filtered prior

to analysis to remove large settleable solids,
SOLID SAMPLE PREPARATION
Prior to chemical analysis aliquots of each solid composite sample can

be taken and placed in a blender with a known amount of distilled water
(varied according to strength of pollutant) and homogenized.

B-4


MICROSTRAINING AND DISINFECTION OF COMBINED SEWER OVERFLOWS, Cochrane Div.,
Crane Co, for FWQA, 11023 EVO, 6/70.

"Modeling the runoff characteristics of an urban watershed by means of an
analog computer," J, Paul Riley and V.V. Dhruva Narayana, EFFECTS OF
WATERSHED CHANGES ON STREAMFLOW, WATER RESOURCES SYMPOSIUM NO. 2, Austin,
Texas, 10/68,

A MULTI-PHASIC COMPONENT STUDY TO PREDICT STORM WATER POLLUTION FROM URBAN
AREAS, AVCO Economic Systems Corp. for Office of Water Resources Research,
EPA, 12/70,

NON-POINT SOURCE POLLUTION FROM AGRICULTURAL, RURAL, AND DEVELOPING AREAS,
Hearings before the Subcommittee on Conservation and Watershed Development
of the Committee on Public Works, H.R., 92nd Cong., 8/72.

“Pesticides and other contaminants in rainfall and runoff," S.R. Weibel,
R.B, Weidner, J.M, Cohen, and A,G, Christianson, JOURNAL AWWA, 58(8):
1075-1084, 8/66,

"Physicochemical and microbiological properties of urban storm-water run-
off," G, Soderlund, H. Lehtinen, and S, Friberg, FIFTH INTERNATIONAL WATER
POLLUTION RESEARCH CONFERENCE, San Francisco, 1970,

"Pollution abatement through sewer system control," W.T. Eiffert and Paul J,
Fleming, JOURNAL WPCF, 41(2):285-291, 2/69.

"Pollution control measures for stormwaters and combined sewer overflows,"
D.D. Dunbar and J.G.F, Henry, JOURNAL WPCF, 38(1):9-26, 1/66.

A PRELIMINARY ANALYSIS OF THE EFFECTS OF URBANIZATION ON WATER QUALITY,
T. Kawashima, T.R. Harmer, and R,E. Coughlin, Regional Science Research
Institute, Philadelphia, Pa., 1970,

PROBLEMS OF THE SOIL MANTLE AND VEGETATIVE COVER OF THE STATE OF CALIFORNIA,
State Div. of Soil Conservation, 1/71.

PROCEEDINGS OF A SEMINAR ON URBAN HYDROLOGY, The Hydrologic Engineering
Center, 9/70.

PROCEEDINGS OF THE NATIONAL CONFERENCE ON SEDIMENT CONTROL, Washington, D.C.,
U.S. Dept. of Housing and Urban Development, Environmental Planning Div.,
9/69. ;

A PROGRAM IN URBAN HYDROLOGY. PART II: AN EVALUATION OF RAINFALL-RUNOFF
MODELS FOR SMALL WATERSHEDS AND THE EFFECTS OF URBANIZATION ON RUNOFF,
P.B.S. Sarma, J.W, Delleur, and A,R, Rao, Purdue U. Water Resources
Research Center Tech. Rept. No, 9, 10/69,


However, total solids is not a useful quality parameter for evaluating
the water pollution potential of urban runoff since the actual compo-

sition of the solids determines its pollutional characteristics.

Previous material provided means to estimate both a contaminant load

and its corresponding composition for a study area or a subarea. Data
regarding the composition of the contaminant load was generally expressed
in terms of micrograms per gram (parts per million) or micrograms per ki-

logram. (parts per billion).

In order to realistically evaluate the water pollution potential of ur-
ban runoff, the total solids ordinates of each quantity/quality hydro-
graph must be modified to reflect other quality parameters such as BOD,
cop, PO,, NO,, etc. The required modification consists of adjusting
the total solids ordinates by applying the composition data of a spe-
cific quality parameter as a proportionality factor, A sample quantity/
quality hydrograph modified to reflect several quality parameters is

shown in Figure 20.

The choice of which quality parameters to select for evaluation is de-
pendent upon receiving water characteristics and standards. It is the
responsibility of the user to designate which quality parameters to se-
lect for evaluation purposes. For example, one may select BOD as the
quality parameter for evaluating a receiving water with low levels of
dissolved oxygen while one may select PO, and No, as the quality param-
eters for evaluating a receiving water which has a significant poten-
tial for eutrophication, The concept of modifying a quantity/quality
hydrograph to reflect other quality parameters is demonstrated in the
latter part of Example 10.

I-62


Average Imperviousness

The hypothetical study area shown in Figure 21 consists of both imper-
vious and pervious surfaces. For the purpose of this example, imper-
vious surfaces will only include rooftops, driveways, and street sur-
faces, Furthermore, it is assumed that runoff from rooftops will

drain onto driveways which, in turn, drain onto street surfaces.

Only impervious area is considered in the computations, hence imper-

viousness is taken to be 100 percent. From Figure 21, it is estimated
that the study area includes about 13 acres of impervious surface area
out of a total area of 27 acres. Impervious area is comprised of two

parts, i.e., street surface consisting of 10 acres and others, 3 acres.

Length of Main Drainage Channel

Using the scale indicated in Figure 21, the length of the main drainage
channel is estimated to be about 1,200 feet.

Average Slope of Main Drainage Channel

The elevation varies from 50 feet to 10 feet over the length of the main
drainage channel. Accordingly, the average slope of the channel can be

estimated by:

50 ft - 10 ft — _40 ft
1200 ft ~ 1200 ft

= 033

II-3


4.0 DETERMINATION OF QUANTITY AND FLOW OF RUNOFF

4,1 General Assumptions and Background

As stated previously, the procedures presented in Section I are intended
to yield a general, first glance assessment of the water quality aspects
of urban runoff, In light of this manual's intended degree of accuracy,

the authors have chosen to ignore runoff contributed by pervious surfaces,

Therefore, it is assumed that no significant amount of runoff will ori-
ginate from pervious surfaces during a storm event of short duration
(i.e., a storm of 30 minutes duration). Moreover, it is assumed that
the amount of rainfall during a storm event of short duration will not
exceed the infiltration capacity and surface retention capacity of per-
vious surfaces and, consequently, the pervious runoff that will occur

is minimal in comparison to impervious runoff.

A short duration, high intensity storm will result in greater quantities
of runoff from pervious areas; however, the quantity of runoff will cause
the pollutant concentrations to be diluted so that it would effectively

be less of a problem than using the above assumptions.

Since street surfaces have been shown to be the primary source of pollu-
tants associated with urban stormwater runoff, pervious runoff will es-
sentially dilute street surface runoff, whereby slightly polluted per-
vious runoff mixes with highly polluted street surface runoff. Since
pervious runoff will be ignored, the manual's assessment of urban runoff

becomes somewhat of a "worst case’ assessment.

By dealing with a storm event of short duration, it has been demonstrated
that pervious runoff can be ignored without serious consequences. How-
ever, interconnected impervious areas other than street surfaces (i.e.,

driveways, parking lots, etc,, which are ultimately connected to a street

1-27


Brush Speed - RPM Percent Residual Debris

Percent Residual Debris

50
40
30
20
10

400
300
200
100

60
50
4o
30

0 Lo =
023 4 5 6 7 8 9 10

0
0 10 20 30 40 50 60 70 80

Wire Broom

irregular Surface 5 alee
L N /
N

Wire Broom
- Flat Surface

ee ee ee

Pattern - inch

Figure 32, The Effect of Pattern
on Residual Debris

Wire Broom

Jot tf |

Percent Debris Rematning

Figure 33, Debris Pickup vs
Brush Sweeper

Wire Broom

n ! [ee es a |
o 1 2 3 4&4 5 6 7
Forward Speed - MPH

Figure 34. The Effect of Sweeper
Speed on Residual Debris

Iv-10


(spunog) pol dog
i-
$3233 3
L 1 1 i 1 rw f-

(40371 ted swer3TTITW) UoTZBIZUeDUCD God

id iJ a
nr r a °
i alk. 1 —_—4.

(spunog) OT X PBOT SPTTOS TBIOL

8

a iJ
ri
T

200

(20977 ted suvz3T TTIW) “OU0D SpTTOS TeI0L

3 8

F 1000,

- 201

120 140 160 180 200

100

80

60

1000

puooeg tog ye0g OFGND '

I-28

Time (Minutes)

Quantity/Quality Hydrograph Developed in Example 10

Figure 30,


is offered by the city, has been very popular, Guidance for the conduct
of community cleanup programs can be obtained from Keep America Beautiful,
Inc,, 99 Park Avenue, New York, NY 10016,

The legal approach to the problem of street surface litter will usually
take the form of establishing definitive ordinances describing improper
littering practices and prescribing penalties for violation. Those
public officials responsible for maintaining clean streets should es-
tablish the antilitter ordinances and should be given adequate legal
authority to enforce these ordinances. In addition to the general anti-
litter ordinances, specific regulations should be directed to the fol-

lowing typical sources of litter in the urban environment:

e garbage and refuse collection

e@ open trucks

@ public litter receptacles

@ refuse dumping

e building construction and demolition
e street construction

@ sidewalk sweeping

@ vacant lots

e "parking lots and garages

e drive-in restaurants

e trailer courts and campgrounds
e sports stadiums

e auditoriums and exhibition halls
e@ theaters

e@ food handling establishments

@ pet control


Appendix C

BIBLIOGRAPHY


Removal Effectiveness (Percent)

8

~~
uw

w
°o

25

°o

t

N
2 3 ry 5
Number of Passes (P)

Figure 31, Removal Effectiveness With
Number of Passes

IV-8


TECHNICAL REPORT DATA

(Please read Instructions on the reverse before completing)

T. REPORT NO.

EPA 440/9-75-004

2.

3, RECIPIENT'S ACCESSIONNO.

4. TITLE AND SUBTITLE
Water Quality Management for Urban Runoff

5. REPORT DATE
December 1974; Issuing Date

|6. PERFORMING ORGANIZATION CODE

7, AUTHOR(S)

Gary Amy, Robert Pitt, Rameshawar-Singh,
Westly L. Bradford, Michael B. LaGraff

la. PERFORMING ORGANIZATION REPORT NO.

9, PERFORMING O}
URS Researc

155 Bovet Road

GANIZATION NAME AND ADDRESS

ompany

10. PROGRAM ELEMENT NO.

1BB034/ROAP 21 ATB/Task 76B

San Mato, California 94402

TT, CONTRACT/GRANT NO.

68-01-1846

12, SPONSORING AGENCY NAME AND ADDRESS
Environmental Protection Agency

13. TYPE OF REPORT AND PERIOD COVERED
Final

Office of Planning and Standards
Washington, D.C. 20460

14, SPONSORING AGENCY CODE

15. SUPPLEMENTARY NOTES.

76, ABSTRACT

This manual provides technical assistance to state and local water quality
management planners to enable them to quantify within reasonable limits the

urban non-point water pollution problem in a local planning area without extensive
data generation, and to make a preliminary evaluation of cost effective abatement
and control practices. The manual prescribes procedures for several levels of
inputs each requiring more self-generated data, with increasingly sophisticated
results.

A state-of-the-art and an extensive bibliography on urban storm water runoff
is presented in the appendix. A glossary is also included.

The manual is not intended to be used as a basis for abatement design but does
provide a guide to data generation for this purpose.

KEY WORDS AND DOCUMENT ANALYSIS
b.IDENTIFIERS/OPEN ENDED TERMS

Drainage Systems, Water
Pollution Controls, *
*Urban Hydrology, Runoff
Pollution Loads

DESCRIPTORS

Drainage, *Water Pollution, *Surface

Water Runoff, *Runoff, *Water Quality,
*Storm Sewers, Hydrology, Hydraulics,
*Mathematical Models

ic, COSATI Field/Group

0808

18. DISTRIBUTION STATEMENT

19. SECURITY CLASS (This Report) 21. NO, OF PAGES

RELEASE TO PUBLIC nciassified 247
20, SECURITY CLASS (This page) 22. PRICE
Unclassified’

EPA Form 2220-5 (9-73)



LENFORMATION MATRIX

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7 . x computer tecbniques for ranoft anoint
2 x rox xox
2 x x x persistence of bacteria
‘ x x slso intornation for seperate sewer aysters
5 X summary of treatmact ecensary to achiowe apecttic
coality
5.5.2, x xx x
7 Washington ¥ ca ¥ ¥—Wiahay wanat?
® X —eumary of trostnoat necessery to echiove apecitic
‘ality
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2 X deep tunnel storage
a Wo, cetitornia x rox x
a2 us. x xx x
ro warviand x Wrbentzation etfecte
u x vabentzntion aftecte
as vs. x s00d tatorastion on detetng compounds and applicetton
procedures
a anes xox x orpantention effect
x» urbentestion oftecte
6 tow York x x
cc 7 ¥ soounte of deicing material used in Valted States
2 X storm standby tanks tor storage
a X —oxtating practices tn 6 cities
2 X —trvorny minott treatment
2 X igh rate ts1sratton
au x comuter techaique for hydrograph developeent
3 ¥—~poroie paveneate wid hydrology effe<te
a No. Caléforaia x x ‘ond noar rondvaye
a Lcntgoe x x wercery sn goite
28 50, California x
» onto x xox x x xox x
20 Arizona x xox x x x
= To, Garon ¥ a x
2 ow Jersey effects of urbanization on flow quantity
2 x ett1ting ponds
TM x xox ik rox
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26 x xox x xox x
37 Wanbiogtos, 9.6. Tigheey araionge minott
2 vs, x xox x
2 x
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“ review of effects of urbanisation on hydrology
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“s ws. x xoxox x x rox x X —anjor otudy throughout United Staton, oeny Analysen
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« X__revlew paper of general charscteristica of runoff
C-12


The maximum peak pollution flush of stormwater runoff was also calculated
and compared to raw and treated sewage. It was assumed that the shock
loading effect of runoff would occur when all soluble contaminants in a
two-week accumulation are washed off the street within a single two-hour
runoff period. The BOD, of the runoff generated under these conditions
was calculated at 11.2 1b/mile of street, This level is approximately
equivalent to 160 percent of raw sewage BOD, and 800 percent of secondary
treatment effluent during the two-hour runoff period,

Catch basins were also determined to be a significant source of shock pol-
lution. The solids that accumulate in catch basins take on the character-
istics of anaerobic sludge and the standing water becomes septic. This
water and some of “the solids can be released into the storm sewer during
even minor rainfall or thaw. Water sample taken from a catch basin in a

residential area revealed a BOD, of 60 ppm,

An extensive study on the water pollution aspects of street surface con-~
taminants was recently conducted by URS Research Company for the Environ-
mental Protection Agency, 21 In this study, samples of street litter were
collected from eight representative cities across the United States. Sample
collection methods included the use of a rain simulator to ensure the col-
lection of very fine, soluble materials that are often not picked up by dry
sweeping techniques, The samples were analyzed for the following pollutants:
BOD, COD, total and volatile solids, Kjeldahl nitrogen, nitrates, phosphates,

and a range of pesticides and heavy metals.

The results of this study were even more alarming with respect to the water

pollution potential of street runoff than the previous mentioned studies,


analyses on selected samples. Additional sampling was conducted on rural
road, highway, and airport surfaces; and particulates were analyzed for
the following common water pollution parameters: BOD, , COD and nutrients,
plus selected heavy metals, for comparison with values representative of

normal city streets.

The loading (1b/curb mile, kg/km) and strength (mg/kg) of the above heavy
metals were determined for various land-use categories, The three general
land-use categories used for comparison were residential, commercial, and
industrial; however, further breakdowns of each of these categories were

also defined and compared.

Industrial areas were shown to contain the greatest loadings of heavy
metals, while both industrial and commercial areas had the greatest
strengths, depending on the particular metal, Cities with high particu-

late levels of air pollution recorded high loadings of heavy metals.

The concentration of heavy metals in storm runoff was found to be 10 to
100 times greater than in sanitary sewage. On a slug load basis (lb/hr,
kg/hr), the metal content of runoff was found to be 100 to 1000 times
greater than sanitary sewage. However, the metal content of storm runoff
is usually not sufficient to cause noticeable reductions in biological

treatment efficiency in plants handling combined sewage/storm drain systems.

The solubilities of heavy metals in a simulated receiving water environment
were shown to be low, most being less than 10 percent of the available
metal. However, copper, cadmium, lead and zinc were found sufficiently
soluble to cause toxic effects to certain aquatic organisms under selected
conditions. In most samples, more than half of all the heavy metals occur-
red as particles smaller than 495 ». The larger particles (> 246 y) were

found to be the most soluble.


EPA/WPD Review Notice

This report has been reviewed by the Water Planning Division and
approved for publication. Approval does not signify that the contents
necessarily reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.

During final review two portions of the method presented herein
appeared to warrant additional comment. The first concerns the selection
of a design storm. The method presented allows the selection of the
design storm without consulting local precipitation or hydrologic data.
The local applicability of calculated results could be improved if the
procedure included at least a brief survey of available precipitation
data. This review of available data could result in a more accurate
estimate of the volume of runoff as well as a better estimate of the

frequency of occurence and the reliability of the proposed stormwater
management system.

The second matter of concern involves the use of impervious area
runoff for the calculation of pollutant concentration. As is stated in
the manual, this assumption results in a "worst case" calculation since
pervious area runoff may provide additional water for dilution. This
additional volume from pervious areas should be considered particularly
in study areas with steep slopes, frequent rainfall events, and
relatively impervious soils,

The method presented here is intended to be used as a first
approximation of the magnitude of the stormwater management problem on
a local basis. Since the manual is applied to specific situations,
weak as well as strong assumptions will undoubtedly become apparent
and refinements of the method will be necessary.


Section V

STATE OF THE ART

An extensive literature review has revealed that the significance of storm-
water runoff pollution was not fully appreciated until about the last ten
years, Although occasional studies revealing some of the water quality
aspects of stormwater runoff were conducted in the 1940s and 1950s, most of
the runoff studies during this period dealt with the quantitative aspects

of runoff.

The earlier runoff quality studies were usually concerned only with water
quality characteristics. This was usually accomplished by collecting and
analyzing water samples within the storm sewers or at the outfall. As the
significance of the problem became more apparent, studies were directed
toward defining and analyzing the sources of runoff pollution; establishing
relationships between water pollution parameters and land use, population
density, traffic volume, etc.; using these relationships to develop methods
or models for predicting the pollution potential of a given area; and sug-

gesting and evaluating pollution control measures,

The following discussion lists some of the more significant and frequently
cited studies on urban runoff, This is not a complete list of urban runoff
studies; it is only a representative sample to indicate the type of work
that has been done in this area. A more inclusive annotated bibliography
and a cross-indexed information matrix has been provided in AppendixC for
further information or background on particular aspects of urban runoff.

1, Characteristics of Urban Runoff

One of the first published studies on the pollution potential of urban
stormwater runoff was conducted in Moscow, U.S,.S.R., in 1936.1 BOD,
samples taken in this study ranged from 186 to 285 mg/z, while suspended


and S = .025. The techniques of Level II are used in the following

assessment,

Determination of Runoff Rate

The selected storm event will be a l-year storm of 30 minutes duration.

Accordingly, the resultant runoff can be determined as follows:

Kinp = 0,85

R = kP

il]

1.0 in./0.5 hr from Figure 4
(0,85) (1,0 4n./0.5 hr) = 1.70 in./hr

t

Therefore, the selected storm will result in a runoff rate of 1.70 in./hr
and a runoff duration of 30 minutes, neglecting the runoff from pervious

areas as usual,

Development of Hydrograph

Unit hydrographs for the study area can be developed by utilizing Espey's
equations, which may be solved graphically with the assistance of Figures
7 thru 11,

From Figures 7 thru 11:

L = 15,000 ft
= 100%
S = .025

II-21


The major limitation of the above relationship is that it can be applied
only to situations where the runoff rate is constant, Unfortunately,
this does not entirely hold true for street surface runoff during a par-
ticular storm event, The actual phenomenon is graphically portrayed in
a street surface hydrograph where there is a rising and receding limb at
the start and finish, respectively, of a rain event, After observing a
typical street surface hydrograph, it becomes obvious that runoff is not
constant at the start or finish of a rain event. Therefore, the previous
equation must be simplified according to the fundamental definition of

numerical differentiation:
P -P = AP = (4.6 Tave PY At

The above relationship is valid for a particular time interval, At, The
tern, Taye’ is the average street surface runoff within the time interval,
Bo is the amount of pollutants at the start of the time interval, P is

the amount of pollutants at the end of the time interval, and Po - Por
AP is the increment of pollutants removed during the time interval.

The above equation can be used in conjunction with the street surface
hydrograph and the impervious area hydrograph of a study area to devel-
op a pollutograph and a loadograph, Utilizing the accompanying work-

sheet (Figure 16a), the procedure is as follows:

(1) Utilizing the respective area hydrographs, select an ap-
propriate time interval at by dividing the time base of
both the impervious area hydrograph and the street sur-
face hydrograph into approximately 20 equal time in-
tervals which are convenient to use, such as 10 minutes,
20 minutes, 30 minutes, etc, A time interval of 10
minutes would be appropriate for a hydrograph with a
time base of about 200 minutes.

(2) Determine the volume of impervious area runoff and
the volume of street surface runoff within each time
interval (obtained from each respective hydrograph and
expressed as cubic feet per second) by the time inter#
val (expressed as seconds), The calculated volumes of
runoff will be expressed in cubic feet.

1-50


Tg (min.)

9e-1

Figure 9, Determination


TI-v

PHOENIX T
PHOENIX 1
PHOENIX T
MILWAUKEE
MILWAUKEE
MILWAUKEE
SILWAUKEE

MILWAUKEE
eucyRuS.
BUCYRUS
‘BUCYRUS
BUCYRUS
BucvaUS
BALTIMORE
BALTIMARE
BALTIMORE
BALTINORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE
BALTIMORE

a2 a8

SEATTLE
SEATTLE
SEATTLE
SEATTLE
SEATTLE

.
.
4
4
4
.
.
4
4
1
4
4
4
1
1
1
1
4
4
t
2
2
2
2
2
2
2
2
2
rn
4
4
.
.
4
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
‘
rn
4
4
.
3
rs
.
5
8
5
5
8
5S
5

WWW OU VERA NNN ANUAVANUAAV NNN AVANANVATUYNIYYNNVYTYVIVOUVIVON Ne ERE ee

ee EDR ARR EEE EERO EE EEE EEE NU UA NUN NAN RIAU YIN x

ops oD. oPOs TROL Ho

Table a-4 (continued)

nm
27000
23000
1000
16000,
44000
24000
26c00
P30n0
17000,
21900
3000
18000
45000
20009
2acod
‘S000
14009
1000
15900,
25000
34000
22000
18000
13000
15000
22n60,
43009
299000
venoe
24000
1009
41000
40000
23000
31000

969e8

Bees
3e1e4

2e7es

1408S

Sene5
16965,
Pitas
184
66765
B0E8
Su8ee
ES
19366
1685
26085
175
Be3e4
18S

s8e6
6eSES
pais
S+6ES

1e2es
7635,
20088
1985
265E8

305E8
sees
16365
2635
1e6e5
Cosas

Bets
5

1sBes
39166

266E:


Cubic Feet per Second

Cubic Feet per Second

200-Acre Industrial Subarea

300 tu. Loadograph nnn ------- 43000
Hydrograph
200-4 +2000
100+ +1000
»
_- — a a oe
T T T T T T
10 20 30 4o 50 60
Time
300 + 100-Acre Residential Subarea p-3000
2004 +2000
a Hydrograph
100 4 1000
Loadogreph—_
10 20 30 40 50 60
Time
Figure 25, Quantity/Quality Hydrographs for Subareas of Example 8

II-16

Total Solids Conc. (Milligrams per Liter)

Total Solids Conc. (Milligrams per Liter)

T
g

Total Solids Load (pounds)

/—750

f

a

8 .
Boral Solids Load ( pounds)

T
8
3



Table 2. EQUIVALENT CURB MILES PER ACRE OF
STREET SURFACE, ARRANGED BY LAND

USE TYPES
Equivalent Curb Miles
Per Acre
Land Use Type Of Street Surface

Open land 53
General residential 54
General commercial Al
Light industrial 43
Heavy industrial 40
All land use types 46

The solids composition is expressed either as micrograms per gram (equi-
valent to micropounds per pound) or micrograms per kilogram, conveniently
referred to as parts per million (ppm) and parts per billion (ppb), respec-
tively.

Therefore, it will not be necessary to convert the solids concentrations
in the runoff water to metric units to obtain the concentrations of con-
taminants associated with the solids. The coliform concentrations are
expressed as numbers per gram of solids (#/g). Therefore, do not express
the coliform concentrations in the receiving waters as ppm or ppb, but as
number/100 m1.

3.2.2 Levels of Sophistication in Using the Tables

e Level I. This level makes use of the tables in the simplest possible
manner to compute the solids concentrations and the associated contaminant
concentrations in the runoff water. Table 3 presents the nationwide means
of solids loading rate and composition, The percent standard error of the
mean indicates the degree of confidence that may be placed on the mean.

This parameter is explained more fully in Appendix A.

I-10


Appendix D
GLOSSARY

Ammonia Nitrogen (NH,} - a form of nitrogen which is an essential
nutrient to plants (can cause algal blooms if all nutrients are
present in sufficient quantities), A product of natural decompo-

sition of fecal matter, urea and other animal protein,

Average Daily Traffic (ADT) - an average value for the daily

vehicular traffic on a specific roadway.

Biochemical Oxygen Demand (BoD, ) - the amount of oxygen required

by bacteria in a five day period while decomposing organic matter

under aerobic conditions,
Cadmium (Cd) - an element of high toxic potential when taken by
mouth and possible association with renal arterial hypertension

at sublethal levels.

Chemical Oxygen Demand (COD) - a determination of organic material.

The sample is “completely” oxidized by chemical methods, instead of
the incomplete oxidation by bacteria in the BOD, test,

Chromium (Cr) - a toxic element when present in the hexavalent

chromium ion form.
Copper (Cu) - an essential and beneficial element in human metab-
olism, but quantities above 1 mg/f tend to impart an undesirable

taste to drinking water.

Cubic Feet Per Second (cfs) - one cubic foot volume of water passing

a point per unit second,


ultimately connected to a street surface via other impervious surfaces.
The estimate of street surface area should include primary and secondary

streets but should not include driveways, alleys, and parking lots.

The main drainage channel of a study area can be a stream, a drainage
canal, or a large storm drainage pipe which traverses the study area and
receives drainage from tributarial sources. Within a given watershed,
smaller tributaries drain into larger tributaries which, in turn, drain
into even larger tributaries, This phenomenon implies a hierarchy of
tributaries which eventually drain into the main drainage channel which
is the ultimate vehicle for collecting and transporting drainage from a
watershed. In certain watersheds, the main drainage channel is easily
identifiable as either a stream or a drainage canal flowing along the
surface. However, in urban watersheds which are entirely serviced by an
underground storm drainage system, the identification of the main drain-
age channel requires further investigation. In such a situation, the
user may use a map of the storm sewer system of a study area in order

to determine the specific storm drainage pipe or pipes which serve as the
main drainage channel. Normally, if the main drainage channel is not
readily identifiable, it can be approximated by estimating the longest
distance of travel for runoff flowing thru the network of interconnected
impervious areas, from the most distant point within the network to the

point where collected runoff ultimately leaves the study area,

The average slope of the main drainage channel can be estimated from a

topographical map of the study area as follows:

Elevation Change of Main Drainage Channel

Average Slope =
Length of Main Drainage Channel

The general approach for describing study area characteristics is demon-
strated in Example 1,

I-6


Assume 600 curb miles in the watershed --

Amt, of Contaminant Removal = (300 1b/curb mile) (600) (0,73)

Amt, of Contaminant Removal = 131,400 1b

Amt. of Contaminant Removal
Volume of Runoff

Concentration xX 16,019

131,400 1b

231,400 1b__ 019
T,508,160 cu ft X (16,021

Concentration =
Concentration = 1,342.3 mg/L

Therefore, the average total solids concentration of runoff is 1,342.9
mg/& while the total load of solids washed from streets is about 131,400

pounds,
EXAMPLE 10

It is proposed that a small artificial lake be created to store storm-
water runoff for subsequent treatment in an existing sewage treatment
plant. A 1-year storm of 30 minutes duration shall be the criteria for
design purposes. Stormwater runoff with a concentration of greater than
30 mg/% of BOD will be stored, while runoff containing less than this
concentration will be directly discharged into receiving waters, What
volume of water should the artificial lake be capable of accommodating?

The study area is located in Dallas, Texas and consists of 2.5 sq mi of
a generally flat urban watershed with an average imperviousness of 60
percent. The impervious portions of the study area consist of street
surfaces, parking lots, roofs, and others, The average contaminant
loading is 400 1b/curb mile with a BOD composition of 30,000 milligrams
per kilogram, Forty percent of the total area is occupied by street
surfaces, consisting of some 150 miles of streets. Assume L = 15,000 ft

II-20


Appendix A

DATA ACQUISITION AND PROCESSING FOR
CONTAMINANT LOADING RATES AND MATERIAL COMPOSITION


listed in Table A-2, The original intention in assigning these codes was
to represent the real variable (conceptually only) by a substitute (surro-
gate) variable which is proportional to the real variable, Unfortunately,
these particular independent parameters cannot be assigned surrogate vari-
ables that meet this criteria. For example, the increasing numerical codes
for climate and season do not necessarily go in any direction relative to
the losding rate or composition, Thus, these codes cannot be thought of
either as true continuous variables or as surrogate variables. The distinc-
tions between categories as represented by the codes.are often gross; the
climatic distinction as shown in Figure A-1 and Table A-3 is particularly
so, but the number of available data records would permit no further re-
finement. It is important to distinguish between areas which receive sub-
stantial amounts of snow from those which receive none, and between areas
where rain occurs frequently and uniformly throughout the year from those

where rains are seasonal, Basically, this is all that the climatic cod-

ing performs,

Approximately 150 publications were initially selected for review. Of
these, about half were deleted from the list because they were too
general in their approach to pollution from stormwater runoff, The re-
maining 70 publications were carefully analyzed and, finally, only 13
provided enough data to be included in the initial data matrix. These
sources provided 153 valid data records, None of the records provided
all of the parameters listed in Table A-l. The available data ranged
in quality and usefulness from a low, wherein the workers merely de-
clared that there were indeed materials on the streets which contained
a high pollutional potential, to a high, wherein the workers accurately
catalogued their test areas and carefully described their methods of
sample collection and analysis, Several publications that contained
data in a form otherwise consistent with that desired were rejected
from consideration because the collection and analysis methods either
were described incompletely or did not appear to be consistent with

those used in the bulk of the available data records,

A-3


Generally, analyses for nutrients and trace metals involved some form
of preliminary chemical extraction of either the dry street dirt or of
the whole runoff sample. The terminal analyses on the extract were
performed by accepted colorimetric or atomic absorption methods. The
BOD;, COD, and pesticides analyses were performed either directly on
solids or on suspensions of the solids according to Standard Methods.
Methods of bacteriological analyses varied slightly between workers,
but the precision of the bacteriological analysis is notoriously poor,
The solids consist of the suspended load in those samples collected at
outfalls and of fine solids which pass a 1/8-inch screen in those

samples of dry dust collected directly from the street.

Four individual studies carried out for EPA provided the bulk of the
data, They are the Tulsa Study (Storm Water Pollution From Urban Land
Activity, AVCO Economic Systems Corp, 11034 FKL, 7/70); the Chicago
Study (Water Pollution Aspects of Urban Runoff, APWA for FWPCA, 1/69);
the URS I Study (Water Pollution Aspects of Street Surface Contaminants,
URS Research Company for EPA, 11034 FUJ, 11/72); and the URS II Study
(Toxic Materials Analysis of Street Surface Contaminants, URS Research
Company for EPA, 1/73). In the Tulsa Study samples were collected at
the main outfall from 16 watersheds within the city. The samples pre-
sumably contained only fine suspended solids and no karge pieces. In
the Chicago Study, samples were collected by sweeping and vacuuming
only, This method is known to leave behind small particles in surface
interstices which can float out when wet. In both studies by URS
Research, street dirt samples were collected by both sweeping and

flushing.

Since no standardized techniques for collection and analysis of street
surface contaminants have been established, the variance in the data
collected from the open literature is expected to contain a large com-
ponent due to variations in methods, This variance component can be

neither eliminated nor evaluated at this time.


Alternative A

The user has available site specific loading rate and solids
composition data. In this case, he may either proceed directly
to subsequent material or compare his data with the data pre-
sented in this manual to verify the analysis and field sampling
procedures, The data for comparison may be obtained by proce-

dures described in Level II of this section,

Alternative B

In this alternative, it is assumed that the user lacks site
specific data and wishes to examine the available published

data for source and reliability.

It is recommended that the planner turn to Appendix A which contains a
narrative description of the sources of data, the procedures for pro-
cessing the data, the procedures for grouping the available data by
categories for detailed analysis, the calculation of the statistical
parameters which describe the data and using those parameters to select

the data most applicable to the specific site.

3.3 Storm Event Characteristics and Impervious Runoff Rate

3.3.1 Method of Computing Runoff Rate From Impervious Surfaces

The determination of a specific runoff rate for an assessment of urban
runoff requires a knowledge of rainfall/runoff relationships, including
the rate of runoff which results from a storm of a specified intensity.
The method of runoff coefficient can be used to approximate the rate of

runoff resulting from a storm event. This technique provides the aver-
age rate of runoff from a storm, although it does not depict the varia-
bility of runoff rate during the storm,

I-18


3. Data Processing

a. Preliminary Evaluation of Data Obtained by URS Research Company

In an earlier study of trace metal concentrations in street surface
materials, the URS Research Company had collected raw data in the form
of solid load in pounds per curb mile and corresponding days since last
the street had been swept or since a substantial rain had last occurred.
The usual method for expressing these two data is as a ratio of pounds
per curb mile per day since last cleaned by either sweeping or rain,
whichever is less. However, theoretically, there is no justification
for this type of transformation. Conceptually, it is probably valid
to assume that solids accumulate on streets by some process at a con-
stant rate (C), and are removed from the streets by a different set of
processes at a rate proportional to the existing load (L). These con-

cepts may be expressed mathematically by the differential equation

where k is a removal constant. The theoretical load of solids on the

street at any time (t), starting with a clean street, is expressed as

From the last equation, it is clear that when t is small, the load in-
creases at a constant rate C; and as t approaches infinity, the load
approaches assymptotically to the value C/k, Thus, the ratio of L/t
(pounds per curb mile per day) appears nowhere in the theoretical treat-
ment, Since the raw data of L and t were available from the URS study,
it was decided to attempt to find out whether the data would approximate

the conceptual model.

A-13


29.

30,

31.

32.

33.

34,

35.

Nickel (Ni) - an element which is very toxic to most plants (espex

cially agricultural crops) but less so to animals,

Nitrate (NO,) - a form of nitrogen which is an essential nutrient to
plants (can cause algal blooms if all other nutrients are present
in sufficient quantities), Product of bacteria oxidation of other
forms of nitrogen, from the atmosphere during electrical storms and

from fertilizer manufacturing.

Organic Nitrogens (OrgN) - “original” form of nitrogenous nutrients,
Gradually converted to ammonia nitrogen and to nitrites and nitrates,
if aerobic conditions prevail, An indication of algal activity po-

tential of a water.

Orthophosphate (OPO Jr a measure of the total inorganic phosphate
content, Other inorganic phosphate forms (polyphosphate) convert
to this form after several hours to several days. Inorganic phos
phate. is an important nutrient to plants, and excessive amounts

can cause algal blooms if the right conditions prevail.

Polychlorinated Biphenyls (PCB) - organochlorine compounds of a

pesticidal nature which are usually used for industrial purposes

(such as plastic manufacture).

Pounds Per Curb Mile (1b/curb mile) - a measure of loading intensity

of a pollutant per unit distance.

Strontium (Sr) - the radioactive form of this element (Strontium-90)
has a tendency to accumulate in bone structures and is a

well-recognized health hazard,


Section III
MISCELLANEOUS SOURCES OF URBAN RUNOFF POLLUTION

Beyond the major source of urban runoff (i.e., stormwater drainage), there
exist several additional sources of pollution which have not been discussed.
These sources include: urban irrigation, cleaning, and snow removal, How-
ever, of these three sources, only snow removal through the use of deicing
compounds has been found to have a significant impact on urban water quality.
Irrigation (i.e., lawn watering, etc.) and cleaning (i.e., washing of cars
and driveways) have negligible effects because of the very small size of
their inputs when compared with other sources of runoff. Snow removal,
particularly in the northern snow-belt states, presents a somewhat larger
source of both runoff and additional pollutants in the form of deicing salts

and their additives.

The current amount of deicing compounds used in the United States has been
placed at 9 to 10 million tons of sodium chloride, 0.3 million tons of cal-
cium chloride, and 11 million tons of abrasives. This use is predominately

in the eastern and north central sectors of the country with 90 percent of

all chloride deicers being used in these areas, The leading states in total
use are Pennsylvania, Ohio, New York, Michigan, and Minnesota, 2 With average
salting rates usually in the range of 400 to 1200 1b/mi/application,” it is
not hard to see why they might add to the sodium chloride levels in adjacent
receiving waters. In addition to the amounts applied to roadway surfaces,
salt storage depots, which are necessary to sustain highway deicing operations,
often become a major contributing source of groundwater and surface water salt

contamination.

The pollutant loading on local treatment plants and/or nearby receiving
Streams due to these operations is of such a magnitude as to become signifi-
cant in locales where deicing occurs on a large scale. In Milwaukee, the

daily chloride loads (in municipal sewage) were shown to be 40 to 50 percent

IlI-1


indicates a range of ten percentage units. These transformations are
carried over into Table A-24, which shows the means and the subscripts
described. It is intended here that the percent standard error of the
mean represents the confidence that may be placed in the value of the
mean for predictive purposes, Subscripts are not given for mean values

of less than five data points.

Table A-24 is constructed so that the total degrees of freedom available
in making a statistical test of significance exceeds ten. The Student

t probability distribution is relatively constant for degrees of free~
dom of 10 or greater, so all discussion which follows is based on 10

degrees of freedom.

Table A-24 may be used directly for detecting functional relationships
between dependent and independent ‘parameters by the simple mechanism of
the Student t test for significance, described in the next section,

For example, referring strictly to the Loading column in Table A=-24,

the following statements can be made: (1) commercial and residential
area means are different at the 97 percent confidence level, (2) com-
mercial and light industrial area means are different at only the 73
percent confidence level, (3) commercial and. heavy industrial area means
are different at the 95 percent confidence level, and (4) the commercial
mean differs from the mean of the set of all data at the 98 percent
confidence level, These four statements were proved within two minutes
by the author, using a hand electronic calculator and a plot of the
Student t distribution, Obviously Table A-24 is an extremely useful
and versatile tool in predicting functional relationships between the

dependent and independent parameters in this study,

The information in Table A~24 is presented in a more useful fashion in
the text as Tables 5, 6, and 7. These tables show only those subset
means which differ from the means of the set of all data at the 95, 90,

and 80 percent confidence levels, respectively. These tables enable the

A-32


28.

29.

30.

31.

32.

33.

34,

35.

36.

37.

38.

39.

40.

41,

"A method of computing urban runoff," W.I. Hicks, Esq,, ASCE TRANSACTIONS,
Paper No, 2230,

"Pesticides and other contaminants in rainfall and runoff," S.R, Weibel,
R.B. Weidner, J.M, Cohen, and A,G, Christianson, JOURNAL AWWA, 58(8):
1075-1084, 8/66.

QUALITY OF RUNOFF FROM DIVERSIFIED URBAN WATERSHEDS, Vishu V, Dharmadhikari,

M.A. Thesis for U. of Arizona, Dept. of Civil Engineering and Engineering
Mechanics, 1970,

QUALITY OF STORMWATER DRAINAGE FROM URBAN LAND AREAS IN NORTH CAROLINA,
Edward H. Bryan, Duke University, Durham, North Carolina, for Water
Resources Research Institute, University of North Carolina, Raleigh
Report No. 37, 6/70.

"Some effects of urbanization on runoff as evaluated by Thornthwaite
Water Balance Models," Robert A. Muller, PROCEEDINGS 3RD ANNUAL AMERICAN
WATER RESOURCES CONFERENCE, Urbana, Illinois, 11/67,

"Stilling pond storm overflow studies," Y.R. Reddy and John Pickford,
JOURNAL SANITARY ENGINEERING DIVISION, ASCE, SA4:609, 8/72.

STORM AND COMBINED SEWER POLLUTION SOURCES AND ABATEMENT, ATLANTA,
GEORGIA, Black Crow and Eidsness, Inc, for Water Quality Office, EPA,
11024 ELB, 1/71.

"Stormwater disinfection at New Orleans," Edgar H. Pavia and Crawford
J. Powell, JOURNAL WPCF, 41(4):591-606, 4/69.

STORM WATER POLLUTION FROM URBAN LAND ACTIVITY, AVCO Economic Systems
Corp. for FWQA, 11034 FKL, 7/70.

STORM WATER RUNOFF FROM AN URBAN HIGHWAY DRAINAGE SYSTEM, K. Morrison
et al,, District of Columbia Department of Highways and Traffic, Washington,
D.C., 8/71.

TOXIC MATERIALS ANALYSIS OF STREET SURFACE CONTAMINANTS, Robert E, Pitt
and Gary Amy, URS Research Company for Municipal Pollution Control Branch,
EPA, 1/73.

"Treatment of urban runoff," F, Condon, APWA REPORTER, 3/73,

"Treatment of urban stormwater runoff," F.L. Evans, III, E.E. Geldreich,
S.R, Weibel, and G,G, Robeck, JOURNAL WPCF, 40(5,2):R162-R170, 5/68,

“urban land runoff as a factor in stream pollution," S.R. Weibel, R.J.
Anderson, and R,L. Woodward, JOURNAL WPCF, 36(7):914-924, 7/64,

Cc-15


Disadvantages of storage facilities include: (1) their large size; (2)
their rather high construction costs; (3) the problem of removing solids
that have settled out; and (4) their dependence on other treatment fa-
eilities for final treatment of the retained water,

c. Open Ponds - The surface storage pond is by far the most frequently
proposed method of runoff storage, Varieties range from simple earthen

dams to concrete or asphalt lined basins,

An asphalt lined detention basin with a storage volume of 8,66 acre
feet was built as an EPA demonstration model in Chippewa Falls in

1969, Although the basin was built to receive overflow from a com-
bined sewer system, the same principles of operation apply to the de-
tention of flows from separate storm sewers, Captial costs for the
project, including the required additions to the capacity of the munic-
ipal treatment plant which finally treated the detained water, were
$6780 per acre of drainage area. Operation and maintenance costs for
the pond and associated facilities during the two-year test period
(1969 and 1970) were $7300 per year.

An example of a multiple use detention basin is contained in an apart-
ment development in Arlington Heights, Illinois, where stormwater run-
off from the site is temporarily stored in a depressed area that is

used as a tennis court during dry weather, The retained runoff is re-
leased into the area's drainage system only after the peak flow of the

uncontrolled stormwater runoff has occurred.

Such local storm retention ponds should be considered in the planning
of storm drainage systems for new communities and in the modification
of existing drainage systems. Such ponds will reduce the peak flows

of runoff resulting from urbanization. They also can reduce the needed
capacity (and thus the costs) of drainage pipes and treatment systems,
If storm retention ponds are constructed prior to the development of

of an area, they can also provide erosion and sediment control for the

area during the construction phase of the development.

IV-17


The variance in the loading rate data exceeds the variance of our repre-
sentation of any single independent parameter as far as can be determined,
Therefore, the probability that any combination of independent parameters
can describe or predict the loading rate (i.e., will co-vary with the
loading rate) is small. The only recourse to extracting information

from the data by covariant analyses is by a factor analysis technique.
Unfortunately, there are not enough complete data records to permit this
kind of study. Furthermore, most of the independent parameters as con-
ceived in this work are not continuous and cannot be mixed with contin-

uous variables in a covariant analysis,

b. Grouping the Data

Since no continuous surrogate variables could be defined to represent the
independent parameters, generally one cannot expect to find continuous
relationships between the independent and dependent parameters. Since
the chances of discovering useful relationships by multiple regression
or curve fitting techniques appeared to be poor, an alternative method
was adopted for detecting systematic changes in the dependent with
changes in independent parameters. The procedure was to (1) group the
data records according to the independent parameters, (2) calculate the
mean and other basic statistics of the dependent variables so grouped,
and (3) test the differences between these means for statistical signif-
icance by the student t and test, This procedure for grouping the data
records provides the mechanism for both detecting significant variations
in the grouped data and presenting the available information which is

readily usable by the urban planner.

The data grouping operation was performed by computer. The entire matrix
in Table A-4 was broken up into 19 primary categories by Land Use, Climate.
ADT, and Type of Landscaping Beyond the Sidewalk. There were enough data
to allow a breakdown by season also, but it was thought to be redundant
with climate and so was not considered. The computer sorted the matrix

into groups to these four parameters, according to the codes shown in

A-15


r 1143 Ft.

Gln Z.4

1143 Ft.

CLLLILELL LLL 2

Impervious Area = 15 Acres

Figure 12b, Impervious Network

1-42


£g-I1

Total Solids Concentration (Milligrams per Liter)

3000-4

20004

1000-4

Figure 29.

nae Aner ne

Pollutograph

40 60 80

Loadograph

[200,000

+ 100,000

100 120 140 220

Time (minutes)

160 180 200 240

Pollutograph and Loadograph Developed in Example 10

Total Solids Load (Pounds)


The above equations allow the user to combine individual quantity/quality
hydrographs of two or more subareas into a composite quantity/quality hy-
drograph representing the entire study area, A value of Poot? De and
ly it can be calculated for each time value, t, by substituting values of
F, Q, and L obtained from the subarea hydrographs into the above equa-
tions. The composite quantity/quality hydrograph can be developed by

plotting values of F %® t’ and Ly t versus time as shown in Figure 19,
A A

D,t’
It may be required to plot many data points to obtain a high degree of ac-
curacy, However, if a rough approximation will suffice, a few data points
may adequately approximate the shape of a composite quantity/quality hy-

drograph.
An example of the above routing technique is given in Example 8, Section II.

The above application of the routing technique was concerned with com-
bining subarea quantity/quality hydrographs into a composite quantity/
quality hydrograph portraying the characteristics of runoff from an en-
tire study area at a point of discharge. However, if the assessment
conducted by the user does not require dividing a study area into sub-
areas, part of the routing technique can be used to simply modify the
time base of a study area quantity/quality hydrograph in order to por-
tray the characteristics of runoff at a point of discharge. The proce-
dure consists of using the nomograph shown in Figure 18 to estimate the
lag time from the inlet of the study area to the point of discharge.
Subsequently, the entire quantity/quality hydrograph is shifted along
the time axis in a positive direction for a distance equal to the lag
time.

6.2 Quality Composition of Runoff

The development of a quantity/quality hydrograph is based upon the re-
moval of solids from urban land surfaces by runoff, Consequently, the

quality ordinates portray the concentration and load of total solids.

I-60


The set of data available for estimating the solids composition in mercury
and several pesticides is very small and unreliable. The means and stan-
dard deviations of that data are presented in Table 4. It is recommended
that the planner place very little confidence in these values; they are

presented primarily for informational purposes and use where it is neces-

sary to estimate loading for these pollutants.

Proceed as follows:

1. Determine the loading rate and composition directly from

Table 3, Attach the data from Table 4, if desired.

2. Convert the loading rate to load per acre of street

\
surface as described.

3. Proceed directly to the next section wherein the load
will be used, Carry the composition data along for

subsequent use.

e Level II. In this level, the user can take advantage of a more de-
tailed analysis of the available data on loading rate and solids compo-
sition. The set of all data was divided into a total of 19 subsets ac-
cording to methods outlined in Appendix A. Whenever the mean of any param-
eter, loading rate of composition, in any subset differs "significantly"
from the mean of that parameter in the set of all data, that number may be
substituted for the mean of the set of all data, The method for making
the determination of "significant" is described in Appendix A. Tables 5,
6, and 7 present those subset means which are different from the whole set
means at the 95, 90, and 80 percent confidence levels respectively. For

convenience of use, the line "All Data” is repeated in each table.
Proceed as follows:

a, Choose the level of statistical confidence permissible in

substituting different values for the means of the set of

I-12


(b) Develop a unit hydrograph for the street surface portion of the
study area assuming that street surfaces represent 35 percent of the

study area,

Slope (S)
Ss = 0,02

Area (A)
A = 320 X 0.35 = 112 acres
street surface

Imperviousness (1)

I 100%

u

Length (L)
L = 7,000 ft

Using Nomograph of Figure 7 in Conjunction with
Figure 8 thru 11

= ‘7 mi
Tp 27 minutes
Q = 165 cfs
TR = 155 minutes
We0 = 37 minutes
Ws = 25 minutes

The resultant hydrograph is shown in Figure 22b.

II-9


INTRODUCTION

The 1972 Amendments to the Federal Water Pollution Control Act specifi-
cally require that non-point sources of water pollution be considered in
the development of water quality management plans for both local and area-
wide planning. In the past, efforts to control water pollution were pri-
marily focused on point sources of water pollution such as effluent dis-
charges from sewage treatment plants and wastewater discharges from in-

dustries,

Significant gains have been made toward the control of point sources of
water pollution primarily because point sources are more obvious in nature
than non-point sources and are correspondingly easier to identify and char-
acterize, The water pollution potential of non-point sources was not fully
appreciated until several major studies revealed that, in many areas, urban
runoff can be a more serious source of water pollution than municipal sew-
age discharges. During the occurrence of some storm events, runoff from
street surfaces alone has been shown to contribute significantly more BOD
to receiving waters than the effluent from a city's sewage treatment plant.
The general quality characteristics of urban storm water runoff are de-

scribed in Table 1.

Although all surface waters have a natural self-purifying capacity for as-
similating water-borne wastes, an urban environment may overwhelm this nat-
ural assimilation process due to the vast amounts of pollutants entering
watercourses from a centralized urban area. Consequently, a systems ap-
proach must be adopted toward water quality management planning in order
to counteract the water quality impacts of urban areas, Such an approach
would focus upon a specified urban area and then proceed to identify and
characterize all sources of water pollution, point and non-point, within

the specified area.


Cubic Feet per Second

Cubic Feet per Second

Cubic Feet per Second

A z Quantity/Quality
Pol lutograph 8 = 2 Hydrograph of Subarea |
€ a& @ Inlet 1
Loadograph— 5 5 IS
= eo 8 a 3
¢ a!
Hydrograph $5 8
B= 18
gs (8
b= Ie
Time ———>
s 3 3 Quantity/Quality
g 5 |2 Hydrograph of Subarea 2
5 . |& @ Inlet 2
&
ae:
an
85 |g
82 13
B= |p
°
Fez 3
cn -_
25 3 Composite
gS Z Quantity/Quality
8 I= Hydrograph of Entire
8 a 3 Study Area at
oa £ [7 Puint of Discharge
B82 3
f= is
ez is

Figure 19. Development of a Composite Quantity/Quality
Hydrograph by the Routing Techniques

I-61


identical if the slope of each subarea is the same,
If the slopes differ, the computed runoff rate will
be highest for the subarea with the greatest slope,

(5) For each subarea, develop a 30-minute unit hydrograph
for both impervious area and street surfaces by util-
izing the equations derived by Espey,

(6) For each subarea, modify the impervious area unit hydro-
graph and the street surface unit hydrograph to reflect
the computed impervious runoff rate pertaining to each
subarea,

(7) Develop a corresponding pollutograph and loadograph
for each subarea by using the appropriate procedure
in conjunction with the impervious area hydrograph
and street surface hydrograph of each subarea,

(8) For each subarea, plot the corresponding impervious
area hydrograph, pollutograph, and loadograph upon a
coordinate system to produce a quantity/quality hydro-
graph representing each subarea.

(9) Modify the total solids ordinates of each subarea
quantity/quality hydrograph to reflect other quality
parameters of concern, If the contaminant load for
for each subarea is identical, this modification can
be made to the composite quantity/quality hydrograph
after it is developed in the next step.

(10) Transform the characteristics of all subarea quantity/
quality hydrographs into a single composite quantity/
quality hydrograph representing the entire study area
by utilizing the routing technique.

The procedure for a Level III assessment essentially consists of con-
ducting a Level II assessment for each subarea and, subsequently,
utilizing the routing technique to combine the subarea quantity/quality
hydrographs into a single composite one, Therefore, the demonstration
of a Level II assessment by Example 10 and the routing technique by
Example 8 should provide adequate insight into the procedure for a

Level III assessment.

I-67


Appendix D

GLOSSARY


FIGURES

Number

onrt our wn

ror
- Oo

12a
12b
12¢
13
14

15a
15b
16a
16b

17

18
19

20

Definition of a Study Area... 1.2. ee ee ee
Contaminant Removal as a Function of Runoff. .
Runoff Concentration as a Function of Runoff. .
1-Year 30-Minute Rainfall... 1... ee ee
Sample Study Area and Corresponding Hydrograph.
Definition of Unit Hydrograph Properties. ...
Nomograph . . 1 1 we ee ee ee ee ee
Determination of TT,  )
Determination of T, Cr
Determination of We0° Ce
Determination of Wa5° Ce
Typical Urban Area, . . 2. + ee ee eee eee
Impervious Network, . . 1... ee ee ee eee
Street Surface Network. . . 6. 6 eee eee
Hypothetical Hydrographs for Urban Watersheds .

Modification of Unit Hydrograph to Reflect
a Specific Runoff Rate... .. 1. ee ee eee

A Sample Pollutograph ........-s ese eee
A Sample Loadograph . .°. . 2-6 ee ee eee
Pollutograph and Loadograph Worksheet .....

A Sample Quantity/Quality Hydrograph Comprising
a Hydrograph, a Pollutograph, and a Loadograph.

A Hypothetical Study Area Consisting of Two
Subareas. 6. 6 6 6 ee ee ee ee te eh ee

Determination of Lag Time ........046-.6

Development of a Composite Quantity/Quality
Hydrograph by the Routing Techniques. .....

A Sample Quantity/Quality Hydrograph Reflecting’

Several Quality Pardmeters, ........

IX

Page

I-4

I-22
I-24
1-25
1-30
I-33
I-34
1-35
I-36
1-37
I-38
I-40
1-42
I-43

1-46
1-49
1-49
I-51

1-56
1-58

I-61

1-63


9e-I1

EXAMPLE 10

POLLUTOGRAPH AND LOADOGRAPH COMPUTATION

TOTAL
STREET SURFACE NOE > IMPERVIOUS TOTAL SOLIDS BOD
At: VOLUME avg 0 AP ZAP VOLUME | CONCENTRATION CONCENTRATION
(min) (cu ft) (in. /hr) (1b) (1b) (1b) (cu ft) (mg/2) (mg/2)
— —
0-10 30,000 0,077 120,000 7,084 7,084 45,000 2,522 75.7

10-20 140,000 0.362 112,916 31,338 38,422 210,000 2,390 71.7

20-30 320,000 0.826 81,578 51,661 90,083 480,000 1,724 51.7

30-40 375,000 0,968 29,917 22,203 112,286 560,000 635 19.1

40-50 315,000 0.814 7,714 4,814 117,100 470,000 164 4.9

50-60 254,000 0.660 2,900 1,467 118,567 380,000 62 1.9

60-70 174,000 0.449 1,433 493 119,060 260, 000 30 0.9

70-80 140,000 0.362 940 261 119,321 210,000 20 0.6

80-90 114,000 0.294 679 153 119,474 170,000 14.4 0.4

90-100 94,000 0,243 526 98 119,572 140,000 11.2 0.3
100-110 84,000 0.217 428 71 119,643 125,000 9.1 0.3
110-120 70,000 0.181 357 50 119,693 105,000 7.6 0.2
120-130 58, 000 0.150 307 35 119,728 87,000 6.4 0.2
130-140 45,000 0.116 272 24 119,752 70,000 5.5 0.2
140-150 35, 000 0.090 248 17 119,769 54, 000 5.0 0.15
150-160 32,000 0.083 231 15 119,784 48,000 5.0 0.15
160-170 24,000 0,062 216 10 119,794 36,000 4.4 OL
170-180 18,000 0.046 206 7 119,801 27,000 4.2 0.1
180-190 13,000 0.034 199 5 119,806 20,000 4.0 0.1
190-200 8, 000 0.021 194 3 119,809 12,000 4.0 0.1
200-210 3, 000 0.008 191 1 119,810 5,000 3.2 0.1


(6) The average total solids concentration of runoff can be
described by the following expression:

Amount of Contaminant Removal (ib)
Impervious Volume of Runoff (cf)

Total Solids Concentration =
(mg/P)

X 16,019

(7) The average concentration of other pollutants can be
determined by multiplying the average total solids
concentration by the composition data of specific
quality parameters,

A Level I assessment is demonstrated by Example 9, Section II.

7.2 Level II

An intermediate level of assessment can be used to investigate an entire
urban watershed or a portion of an urban watershed. The characteristics
of the study area are considered homogeneous and a single quantity/quality
hydrograph is developed for the entire study area. The procedure is as

follows:

(1) Describe the specified study area according to the fol-
lowing characteristics: study area size (acres), amount
of interconnected impervious area within study area
(acres), amount of street surface area within study area
(acres), length of main drainage channel (feet), and
average slope of main drainage channel (feet/feet).

(2) Determine an appropriate contaminant loading for street
surfaces within the study area.

(3) Select a storm event according to the criteria presented
and compute the impervious runoff rate,

(4) Develop a 30-minute unit hydrograph for both the inter-
connected impervious area and the street surface area
within the study area by using the equations derived by
Espey.

(5) Modify the impervious area unit hydrograph and the street
surface unit hydrograph to reflect the computed impervious
runoff rate.


98-V

GINCINNATT
Tuscon

TUSCON
CINCINNATI

TULSA
SAN JOSE T
PHOENIX 1
MILWAUKEE
ByCYRUS

BALTIMORE
¢ ian
ATLANTA

TULSA
PHENI 11

Uew/0Lo/siNng
LowsOLo/HULT

HH

SEATTLE
SEATTLE

BOSE FRU UNUUNINUNNS TEUONNE EEE EEE EEOC ARAN ENNE NEES ENUNNUEEE FEE EEE UNIT oO

CUNTUNUUNANNUVINAINNUUU NANA NON Hens £ FOO CCOUNNNA MMH FOCCOOUUIMWOOUNHSUOOOS w

907
1065
82

Tet
1105

23
3

3

RepUNNEe o
eee o

i
cr

y
2
q
2

26

59
2
9

60

12

LUNE NNNUOY HEHE OCOHOCO UNE HmONNH Me
Heme meeme meee meet smsasans sate sebenees benepe bebe neteeaeuenestene coeeeeteeene mtn enteteReeese tone eteeene Rete

Pop eanene ea COTO TUR Ra Ee este ea ane Rent nans Se ne Dene cata ea Eee Ea enecte beheeeecscenen ne Unemene saseenee eRU ES

Home

Table A-19.

1890
167000 611000 6670 2720 5390
175000 525000 5080 1810 4940
‘84800 423000 1810 1920 1880
76900 800000 2680 1960 3280
78800 526000 5790 3110 2630
75000 883000 48804400

22300 282000 580 16900

2300 3620
3

meee wee

ee perara ru ate ap enee ee enna ee en RU POE ee HAND RUA FOEU EO EOHUTY 9

LANDSCAPING BEYOND THE SIDEWALK 1 - GRASS

mmm TOOL: Fou



Hydrograph Characteristics from Total Impervious Area

TR = 34 min,
Q@ = 1,100 cu ft/sec
Ty = 210 min,
Ws0 = 48 min.
Ws = 31 min,

Hydrograph from street surface runoff will have the same above charac-

teristics except

Q = 736 cfs

The resultant unit hydrographs are shown in Figure 27.

The unit hydrograph must be modified to reflect the selected runoff
rate and duration. The unit hydrograph reflects a runoff rate of
2 in./hr and a runoff duration of 30 min, while the selected runoff

rate and duration are 1.70 in./hr and 30 minutes, respectively.

The duration of the unit hydrograph and the selected runoff duration
are identical; therefore, no modification of runoff duration is re-
quired. However, the unit hydrograph is modified to reflect the se-
lected runoff rate by multiplying the ordinates of the unit hydrograph
by:

Selected Runoff Rate | 1.70 in./hr
2 in./hr ~ 2 in. /hr

0.85

The resultant hydrograph, modified to reflect the selected runoff rate,
is shown in Figure 28,

II-22


EXAMPLE 5

Select a l-year storm of 30 minutes duration for a study area in Portland,
Oregon and determine the runoff rate and duration resulting from the se-~
lected storm event, The runoff coefficient for the study area is 0,9

considering only the impervious areas,

Solution

Figure 4 reveals that a l-year storm of 30 minutes duration in the vicine=
ity of Portland, Oregon will contribute a total of 0.4 inches of rainfall.
Since this 0.4 inches of rainfall occurs over a 30-minute interval, the

average rainfall intensity of the storm will be 0.8 inches per hour.

The runoff rate of the selected storm event can be determined as follows:

= kP

0.9 (0.8 inches/hour)

0.72 inches per hour

Therefore, the resultant runoff rate is 0.72 inches per hour while the
resultant runoff duration is 30 minutes. It should be noted that time-

base of the hydrograph will extend over a longer period than 30 minutes.
EXAMPLE 6

An urban study area consists of a rectangular parcel of land with a length
of 1,0 mile and a width of 0.5 mile. The length of the main drainage chan-

nel is 7,000 feet, the average slope of the main drainage channel is

2 ft/100 ft and the average imperviousness is 55 percent.

II-7


an csw mm Sc A ms R 5 M Loi  BoDS cop GPO TPO Ho). mRG SUC] HME SRM CTOMLE POULT
DURHAM 20 20 %7 10 22 4 s20 4005300 68s 2 7 10485
Bumiar £8 go use 13 fad ie foe S808 S880 m i?

DURHAM 2 0 20 ‘Bz 10 Paid is 330 6

tawaence «30.20 paid 210 ig900 61600 11600

GWWARBAR = «TB O : 18800, 2620 "650 595535

INN ARooR = 13 Bo : 307 2770 8Co 730388

ANN ARBOR 14 20 : 23300 2130 M9

GRAND RAPIDS 1 9 20 8 os 3B ee00 a7 4

Tuscen 43 25 2 2730 10787
Teme SO 2 980 TASES
ANWAR 19 20 ‘ 179 23800 2510 630 660450
CHICAS 1 3 2 19 ai ie ‘DB “Teo 328
cHECAGD 4 3 20 15 22 32 fe 3 523
cHicAGe i 3 20 50 24 32 121 else 23
CHICAGE 1 3 20 50 33 32 18 2810 773
CHICASE i 3 20 20 22 32 ‘a 4770 a7
cutcace 13 2 20 22 32 68 405
chicace 1 3 20 15 23 32 wt 0: as
cHicAse 13 20 20 23 32 138 6320 670
CHICAGE. 13 20 13 32 168 2R80 961

CAGE 1 3 20 12 72 13 deno ses
cHicASe 1 3 20 18 72 2 pan sea
cHICASe 23 20 22 32 36 i980 vee
cHicaGe 43 20 23 72 153 356

ULSA 20 20 aid $0 11600 2200
quLsa 20 20 222 22 67300 2700
musa 20 20 eid 32 13000 1300
TULsA 20 50 iia 39300 tooo
Tusa 20 20 3 24 28000 i600
TULSA 20 20 32 33 28000 4200
TULSA 2 0 20 raid 1 32100 3100
prey 2 0 20 i 28 43800 £400
SAN JOSE I 4% 20 . t te 2 70 47000 3600 2300 71 24000 2700 460 96 8

ENT X a 1 20 1 a 1206 2 32 10001 450, 2300 120 21000 1500 840 15 44
MILWAUKEE 1 2 20 t 1 0 7 2 2700 ‘4400 20 $30 160 18000 830 22 28

RU 1 2 20 i ot 2 7 3 “Bo 33 33 ‘90 21000 89047017
BALTINGRE 2 2 20 1 1 26 4 1 260 61000 38 1900 160 24000 2200, 480 31 at
SAN JOSE IT 4 2 20 ya 5 2 86 as Lago 35 28000 300° 60 87 16
Atay 2 20 rf 2 1% 1 2208800 35 4100 120 24900 60 350 12

hay 23 3 st Ene : 3 2088 32 15808 3 38 3
PHOENIX 114 2 0 tou 2 i 130 5200 87 18000 620 490 1136

ATTLE 5 3 20 tot eo 10000 35 200% 89 23000 2100 460 42 it
Lewsorsing 6 0 at tot 372 19000 se 2200 110 24000 1600 420 38 26
Couvatormunr § 0 22 pt 853 22000 bs 2200 ‘30 20000 1300 330 28 19 3
HED/NER/SING 6 0 23 tot Sia 12000 rn 2200, Bi 18000 1200 20 36 52 290 41268
NeDseLo/sing ¢ 0 20 too4 ee 2200 34 20000 i600 370 13 18 530
HED/OLO/MULT § 0 25 14 7100 8s 2200 59 24000 1900 330 te 12 350 14185
SAN JOSE 8 8 Bt tad wz 2 0 a& 27000 2600 4808513320
SAN JOSE 4 4 22 ted is 2 a8 36 23000 2000 480 89 47 370
SAN USE T 8 4 28 tid 2 ek 33 2000 2100 350 100 5 240
PugeNIx't = 1 aL tat i 8 2 77 159 23000 1200 320 7
PHOENIX IT = § 1 22 221 a1 2 238 39 47000 3700 280 13° 210
PHOENIX f 8 23 fou i732 fs 140 21000 “370 680 2s 133:
PHEENTX Tg 4 5 TE 132 3, $3 23000 3600 $40 42 430
MILWAUKEE, 12 a pad o 7 2 193 83 15000 790 280 33 21 300 969E% 2068)
Micuauxee = «12 22 ta 4 & 6 2 33 170 tho09 580 230 “0 Bh 0
MILWAUREE =f 2 23 244 0 72 40 125 \g000 570 280 26 78280
Fitwaukee = $B Bs tet 09 8 770 ye 15000 $70 230 18 «20 210 Beare
BUCYRUS 12 2 234 2 2 350 31 13000 350 420 13 33 190
BUCYRUS 1 2 23 bot 2 2 205 66 15000 430 370 36 33 110

CYRUS 32 2 toi 2 2 380 5% 22000 1600 430, rr
pacrinsee «BO Be 113 2% 4 1 109 120 19000 1700 290 45 28 630
Bacrimare = 2223 244 oi 87 420 24000 1000 430 35 23760 14088
BALTIMORE 2 2 a 104 2 5 1 3 120 15000 730 150 2 5 730
BALTIMORE = «2225 tot a Fi 33 $50 18000 1500 270 18 6 890
SAN vOsEIT 4 2 21 pad s 2 it 130 48000 5700 560 120 28 810 Se3ES
SAN JOSE II 4 2 22 aed 59 2 8 34 11000 600 230 30 «21 240 1e9ES
Ban yase P42 23 pa 52 33 26000 3900 870 78 "9 420 QetEA
STLanta 22 a paid 2 1 i 150 24000 260 210 «8 «| «3270 BOE.
ATCANTA 2 2 2 244 212 $9368
ATLANTA, 2 2 23 paid 2 ai 7 13000 480 28 «7 + tao 1e8es
ATEANTA 22 25 tai 2 28 1
Tusa 22 2 23 crear 160 20000 1100 430 32 78
Tulsa 22 23 224 3 4 Ts 17000 “370 $20 dO 10
TULSA 22 3 221 54 1400 230 1000 220
PHOENIX IT 8 2 a1 i354 6 2 35 21000 380 700 1128380
PHOENIX TI 2 BB toa 6 2 7% 20000 2000 37 93 83250

ENIX IT 8 2 23 rad 62 52 i100 220 850 9 (12 430
PHOENIX 1182 88 i2t sb 8 SE 25800 2500 32g 7 iB a
SEATTLE 5 3 2 pad ew of 8 27000 1700 #30 39 13 460
SEATTLE 8 3 be a3 ze ot 400 37000 3000 430 40 660 beaes
SEATTLE 5 3 24 2g. 12 1 ee 67 23000 2500 460 29 3 460
SEATTLE 53 2 123 12 1 42 48 59000 2600 449 39 410 30168

Table A-7 LAND USE 20 ~ RESIDENTIAL



Té-V

cur

DURKAP
DURHAM

TULSA
BALTINORE
BALTIMORE
BALTIMORE

BACTIMBRE
ATLANTA
ATLANTA
DICANTA
ATLANTA
ATCANTA
ATLANTA
ATLANTA
ATLANTA

Table A-12,

BoDS5 oD TPOS HOS MAR,

5300 65500 ae
5800 49000 1600 490
29300 163000 3200 3600
11600 91700 2800 2200
24200 168000 1800 1600
67300 519000 3300 2700
35000 267000 2500 1800
19000 114600 1600 1900,
39300 298000 3000 1800
24000 277000 2400 41600
25300 247000 1600 1900
25000 207000 1500 1200
39600 222000 2700 1900
32190 192000 2600 3100
48290 90900 1700 4700
$3900 158000 3000 i400
63000 20000 1090 38 1300
8500 30000 620, 55 1100
43000 31000 1700 37 2000

CLIMATE 2 - SOUTHEAST

417
137
66

SPOR BTS oo

woke w

110
6



@, Discharge in CFS

50
4s
0 Za
\ Total Area
° t ¥
30
\ Impervious| Surfaces
25
[ Saree Surfaces
15
cee
/ L ) SO
5 NO aN
V YY Pervious Surfaces i
P——_|
o! 23 50 7S 100 150
Tr Time in Minutes
Figure 13. Hypothetical Hydrographs for Urban Watersheds

1-44


1143 Ft, —_
SSAA SN ANNANSAAARAN N my
ae GN

T
4
Y]
Y

TS
A Soy,
TES

LL,
y
y
y
y
4

ZL

Nay

Se
SOL
PHY

1143 Ft.

Y
Z
Z
a
y
%
4
Y

GEES

TIL
SS
_—~

Ro
S
LLLLAL1

Soy AAANANANNERNN SY SSMS Y
Residential Approximately
Block 30 Feet Wide
Streets
Total Area = 30 Acres Street Area = 10 Acres

Z Off-street Impervious Area
(Roofs, Driveways, Etc.)
= 15 Acres

Total Impervious Area = 15 Acres

Figure 12a, Typical, Urban Area

I-40


Therefore, summarizing the chronology of the urban runoff phenomenon:

(1) Contaminants accumulate upon urban land surfaces.

(2) A rain event dislodges and removes some contaminants from
urban land surfaces,

(3) Runoff transports contaminants across urban land surfaces,
into gutters, and thru storm sewers.

(4) Runoff eventually discharges into a receiving water.

The analytical methods in this section will attempt to simulate the phe-
nomenon of urban runoff as described above, The ultimate product of this
simulation will be a graphical representation of the quantity and quality
characteristics of urban runoff originating from a defined study area un=-
der specified conditions, The simulation will generally consist of the
following:

(1) Define an urban study area.
(2) Describe the characteristics of the study area,

(3) Estimate the amount and composition of various contami-
nants found upon street surfaces within the study area.

(4) Select a certain storm event which will generate runoff
and remove street surface contaminants from the study
area,

(5) Develop a graphical representation of the quantity and
quality characteristics of runoff originating from the
study area,

The step-by-step analytical procedures for accomplishing the above simula-
tion are presented at the end of this section beginning with paragraph 7.0.
The procedures are identified according to three levels of assessment, each

yielding a correspondingly higher degree of accuracy.

Paragraphs 2,0 thru 6.0 of this section contain theory and support material
to be utilized by the analytical procedures of paragraph 7.0. It is recom-
mended that users of this manual make a concentrated effort to gain a basic
appreciation of paragraphs 2,0 thru 6,0 (and corresponding example problems)
before attempting the analytical procedures of paragraph 7.0,

I-2


4.4 Development of Unit Hydrograph for Entire Study Area

The following procedure provides a means of developing a unit hydro-
graph which portrays all runoff, impervious and pervious, from a study
area, This procedure will subsequently be modified in such a manner as

to ignore pervious runoff,

A method of synthesizing unit hydrographs for an entire study area is
given in a study by Espey” who collected data from 11 urban watersheds

in Houston and 22 urban watersheds in different geographical locations
within the United States, Multiple linear regression analysis was used
to develop general equations which describe the 30-minute unit hydrograph

for urban conditions,

The problem of using statistics to synthesize a unit hydrograph is by
definition one of approximating the hydrograph shape, The approach
used by Espey was to describe the hydrograph in terms of typical hydro-
graph dimensions instead of attempting to derive an actual mathematical

function for the hydrograph.
To describe the hydrograph, the following parameters were chosen:

q@) Ty

from the beginning of surface runoff/to the peak runoff,

the time of rise, defined as the time, in minutes,

(2) Q, the peak discharge, defined as the peak value of dis-

charge, in cfs,

(3) Ty the base time, defined as the time, in minutes, from

the beginning to the end of surface runoff

(4) Wo? the time, in minutes, between the points on the
hydrograph when the discharge represented by %o is
half the peak discharge.

(5) Was the time, in minutes, between the points on the

hydrograph when the discharge represented by G5 is

three-fourths of the peak discharge.

I-31


Figure

VA

Determination of T.

R


7.0 ANALYTICAL PROCEDURES FOR THE ASSESSMENT
OF URBAN RUNOFF QUANTITY AND QUALITY

7.1 Level I

A simple, first-glance assessment of the water pollution aspects of
urban runoff is to consider only (1) the volume of impervious runoff
and (2) the amount of street surface contaminants removed by street
surface runoff, In turn, the rate of runoff with respect to time is

ignored, The procedure is as follows:

(1) Describe the specified study area according to the
following characteristics: study area size (acres),
amount of interconnected impervious area within study
area (acres), amount of street surface area within
study area (acres), average slope of main drainage
channel (feet/feet).

(2) Determine an appropriate contaminant loading for
street surfaces within the study area,

(3) Select a storm event according to the criteria pre-
sented and compute the impervious runoff rate,

(4) The volume of runoff from the interconnected imper-
vious area can be estimated by the following:

Impervious Volume of Runoff (cf) = Runoff Rate (in./hr) X
Interconnected Imper-
vious Area (acres) X
1,815

(5) The percentages of street surface contaminants which will
be removed by various combinations of runoff rate and run-
off duration are given in Table 9, The amount of contam-
inants removed from the study area by the selected runoff
rate/duration can be estimated by the following:

Amount of Contaminant Removal (1b) Contaminant Load Per
Acre of Street
Surface (lb/acre) X

Amount of Street

Surface Area

(acres) x
Percent Contaminant

Removal/100

1-64


a, High Rate Trickling Filters

A high rate trickling filter process has treated flows up to 10 times
average dry weather flows. Removal efficiencies for both organic and
solids were approximately 65 percent. The cost of required plant ad-
ditions was $1,550/f/sec ($68,000/mgd) of capacity.

4, Physical-Chemical Treatment

Although at the present time construction costs are high, physical-
chemical treatment is becoming competitive in cost with biological
treatment, Physical-chemical processes are of particular impor-
tance to stormwater runoff treatment because of their adaptability to
automated operation, rapid startup and shutdown, and very good resis-

tance to shock loads.

Disadvantages of physical-chemical treatment, in addition to the high
construction costs, are high chemical requirements and problems of

sludge disposal,

In a recently completed pilot study for the EPA, a complete physical-
chemical process (comparable to secondary treatment) was developed and
tested, This technique, which incorporated chemical clarification fol-
lowed by adsorption on activated carbon, resulted in removal efficiencies
of 94 percent of BOD and 99 percent of suspended solids. It was deter-
mined that a 10-mgd facility of this type could be developed at a cap-
ital cost of $1.8 million and an operating cost of 19¢/1,000 gal),

Iv-23


The following discussion on storage and treatment of stormwater runoff
is abstracted primarily from a recently completed EPA state-of-the..art

document entitled, Urban Stormwater Management_and Technology: An

Assessment, 1973.
a. Flow Rate Control

Several methods have been proposed for controlling the flow rate of
runoff waters into treatment facilities, The following is a brief
description of these various methods, including the advantages and dis-
advantages of each and construction and maintenance cost estimates

where available.

b, Storage Facilities

One of the most effective methods of controlling the flow rate entering
the treatment plant is to store the runoff during peak flows and dis-
charge it to the treatment facilities at a controlled rate during sub-
sequent low flow periods. Storage is perhaps the most cost-effective
method available for managing urban runoff, and it is the best docu-

mented stormwater pollution control measure in present practice.

Examples of runoff storage facilities include open ponds, steel and
concrete tanks, underground tunnels and caverns, existing sewers, and

underwater collapsible tanks,

Advantages of such storage facilities are: (1) they are generally simple
to design and operate; (2) they are relatively unaffected by rapid
changes in runoff flow rates and quality; (3) they frequently can be
operated in concert with existing waste water treatment Plants; and

(4) they can serve as preliminary sedimentation basins, there reducing

the sediment handling requirements of subsequent treatment processes, *

Iv-16


MANUAL FORMAT
In order for the manual to be used effectively, users should familiarize
themselves with its structure and content. The manual contains five prin-

cipal sections and several supplemental appendices.

Section I An Assessment of Urban Runoff Quantity and Quality

This section provides analytical procedures to pre-
dict the quality, quantity, and rate of runoff re-
sulting from street surface contaminant removal by

specified storm events.
Section II Example Problems
Example problems to demonstrate the concepts and

analytical procedures of Section I,

Section III Miscellaneous Sources of Urban Runoff Pollution

The preceding sections are concerned with urban run-
off resulting from rainfall. This section considers
other sources of urban runoff such as urban irriga-

tion and snowmelt,

Section IV Treatment, Abatement and Disposal of Urban Runoff

Methods for treatment, abatement and ultimate dis-
posal of urban runoff are discussed. Preceding

this discussion, general criteria is provided for
an evaluation of the water pollution potential of

urban runoff,

Section V State-of-the-Art
Provides background information regarding major rele-
vant studies conducted in numerous geographical loca-
tions since 1936, Emphasis is placed upon recent
studies which were used in the development of this

manual,


d. Storage Tanks — Steel or concrete storage tanks can be used to detain
runoff in areas where surface ponds are physically or economically in-
feasible because of the large land requirements, Although construction
costs of tanks are high compared to the costs of surface ponds, tanks

do not require the algae and mosquito control measures that are often
necessary in open storage facilities; and they can be designed for

easier removal and disposal of settled solids,

e. Underground Tunnels - Due to the lack of usable surface area for de-
tention ponds or even storage tanks, underground tunnels or storage
caverns are being mined 200 to 300 feet beneath Chicago to provide
storage for combined sewer overflows. The underflow-storage tunnels
will have a total capacity of 18,000 acre feet, A 2,5-mile-long test
tunnel was mined at a cost of $1.5 million,

f£. Use of Existing Sewers ~- With the use of a computerized sewer moni-
toring and control system, the city of Detroit can utilize existing
sewers in the downtown area for runoff storage. A complex array of
rainfall and overflow monitors coupled to a central computer can better
utilize the existing capacity of the sewers by moving high flows to
areas of the system experiencing low flows. The cost of the project

has been estimated at $2.2 million.

g. Underwater Storage - A rather unique solution to the problem created by
the lack of usable surface area is the use of underwater collapsible
tanks. In a pilot program, 100,000-gallon collapsible tanks were an-
chored offshore from Sandusky, Ohio, in Lake Erie, Stormwater over-

flows were diverted into the tanks and later pumped ashore for treatment,
The project cost was $2 per gallon, but projected future costs were

Placed at 40 cents per gallon.

Iv-18


The characteristics of the urban watersheds upon which Espey based his

equations were within the following range of data;

Area of Watershed: 8,2 to 59,000 acres
Length of Main Drainage Channel: 560 to 123,000 feet
Slope of Main Drainage Channel: 00047 to .146 feet/feet

Using the equations derived by Espey, one may synthesize a unit hydro-
graph to describe an entire study area, Although the required cal-

culations are reasonably simple, a certain degree of subjectivity will
be involved in actually drawing the shape of a unit hydrograph in terms

of the graphical variables Tp Q, T, Wo5)+ An example of unit

B’ W50°
hydrograph synthesis using Espey's equations is given in Example 6 of

Section II,

4,5 Development of Unit Hydrographs for Impervious Area and Street
Surfaces

As presented in the previous section, Espey's equations enable one
to develop a unit hydrograph for an entire study area, comprised of run-
off originating from both impervious and pervious surfaces, However,
subsequent procedures require the development of two other unit hydro-
graphs; one which describes runoff from interconnected impervious sur-
faces and another which describes runoff originating from street sur-
faces within the study area, Consequently, the authors of this manual
have taken the liberty of adapting Espey's equations to satisfy the

needs of the manual as follows,

Figure 12a shows a typical urban study area comprised of about 15
acres of pervious surface and 15 acres of impervious surface, of which
about 10 acres are streets. Using Espey's equations, one can normally
develop a unit hydrograph for the entire study area and subsequently

modify it to reflect a specific runoff rate.


CONTENTS

(Continued)

Section Page
I 5.0 Quality of Runoff... .... 1. ee ee + 148
6.0 Quantity/Quality Hydrographs ....... + I-55

6.1 Method of Routing Quantity/Quality
Hydrographs .... . oe 2. 1-55
6.2 Quality Composition of. Runoff wee ee) 1-60

7.0 Analytical Procedures for the Assessment
of Urban Runoff. Quantity and Quality... . I-64
Tl LeveL De. ee ee ee eee ee 1H 64
7.2 Level 11, 6. 1 1 eee ee ee ew ee 185
7.3 Level IIT... ... re <1.)
REFERENCES. . . .. 1. . eee . «e+ I-68
It EXAMPLE PROBLEMS. . . . 6 ee ee ee ew ee ew ee) 6TTHD
Example lw. we ee ee ee ee ee ee ee ee) 6IHD
Example 2.0. 6 6 ee ee ee ee ee ee ee we TEM
Example 3... 6 6 ee ee ee ee et ee ee we «LING
Example 4.0. 6 6 pe ee ee te ee ee ee we TTC
Example 5... eee ee ee ee ee ee ee ee TNT
Example 6 © Sa
Example 7... 1 ee ee ee ee ee ee ee ee TED
Example 8. 6 6 ec eee ee ee ee ee ee ee 6TH
Example 9... 06 6 eee ee ee ee ee ew ew ee) «TEH1O
Example 10... 6 6 ee ee ee ee ee ee ew ee) 6 «TH20

III MISCELLANEOUS SOURCES OF URBAN
RUNOFF POLLUTION. . . . 6 ee ee ee ee ee es TIL

References. . 2 6 6 eee te ee ee ee we ow ee TTT

Iv TREATMENT, ABATEMENT, AND DISPOSAL

OF URBAN RUNOFF... 1 ee ee ee ee ee eee TWH
A. Evaluation of Urban Runoff Quality... .. IV-1
B. Source Abatement . . 6. eee ee ee oe ee TVD
c. Technical Abatement. . . 1... ee ee ee) IVS
Improved Street Cleaning Practices ..... IV-6
Air Pollution Controls... ... 44.4.4. +. IV-12

VI


Table A-5,. MEAN CHLORINATED HYDROCARBON AND MERCURY CONCENTRATIONS IN
URBAN STREET DIRT FROM SEVERAL U,S, CITIES (THE URS I STUDY)

Concentration in Micrograms/kilograms of Dry Solid

Methyl
DDT Lindane Parathion DDD

Methoxy-

City Hg Endrin Dieldrin PCB chior.
San JoseI 330 2.2 12 1300 0 120 19
Milwaukee ie) 3.8 1300 3100 0.4 1.2
Bucyrus . 0 12 470 1200 43 i)
Baltimore . ie) 3.0 1000 170 30 0
San Jose II 14 0 4.4 100 oO 28 1)
Atlanta 53 0 55 150 i) 30 oO
Tulsa 59 i) 74 200 0 39 0
Phoenix II 24 0 26 71 i) 14 .
Seattle 15 ) 59 2300 ) 380 .
Mean 83 0.2 28 770 500 76 2.9
Standard 111 28 770 1050 118 71

Deviation
Range 14-330 0-2.2 3,0-74 71-2300 0=3100 0,4-380 0+19
N 6 9 9 9 9 9 7

22

0

73
0.2
61
100
20
79

100

270

82

78

2-270

A-12


Consulting tables of Student t with 10 degrees of freedom, the probabil-
ity that the Null Hypothesis is true is >0,.90, Therefore, there is no
significant difference between these mean values, Using the original
data, Student t is calculated as 0.048 and the same conclusion is ar-

rived at: that the difference in the means is not significant.

Problem 2:

Question: Is the mean Pb concentration in solids from areas
with ADT>15,000 larger than from areas with ADT

500-5000?
Given: Pb @ ADT = 500-5000 = 1060,
Pb @ ADT>15 ,000 = 2230,

Subscript c 20-29% average = 25%

Subscript b = 10-19% average = 15%

3, = 1060 x 0.25 = 265

So = 2230 x 0.15 = 334

«, Re eraeee

Student t = 2230 - 1060 _ 1170 _ 2.74

Consulting tables of the Student t distribution with 10 degrees of
freedom, the probability of the Null Hypothesis’ being correct is
0,020. Therefore, the difference is significant at the 98 percent con-
fidence level. Using the original data, Student t is calculated as
2.53 and the confidence level of the difference is actually 97 percent
rather than 98 percent. The decision remains the same, however, The

difference in the means is highly significant.

A-36


"Urban runoff by road research laboratory method," discussions by Leaonard
H. Watkins, Franklin F, Snyder, Harvey W. Duff, and George C.C, Hsieh,
JOURNAL HYDRAULICS DIVISION, ASCE, HY7:1625, 7/70.

"Urban runoff by road research laboratory method," discussion by D, Earl
Jones, Jr., JOURNAL HYDRAULICS DIVISION, ASCE, HY9:1879, 9/70,

URBAN RUNOFF AND BASIN DRAINAGE STUDY, LAKE WASHINGTON (CEDAR RIVER) AND
GREEN RIVER BASINS, SEATTLE, WASHINGTON, Seattle District, Corps of
Engineers, 7/72,

URBAN RUNOFF CHARACTERISTICS, Division of Water Resources, Dept. of Civil
Engineering, U. of Cincinnati, Interim Rept. of the EPA Water Quality
Office, 11024 DQU, 10/70,

URBAN RUNOFF IN LAKE COUNTY, ILLINOIS; A REASSESSMENT OF THE ROLE OF URBAN
RUNOFF IN THE POLLUTION OF LAKE MICHIGAN, State of Illinois, Lake Michigan,
and Adjoining Land Study Commission Rept. to the Governor and the 77th
General Assembly, Vol. II, 10/71.

URBAN SOIL EROSION AND SEDIMENT CONTROL, National Association of Counties
Research Foundation, FWQA, 15030 DTL, 5/70,

URBAN SPRAWL AND FLOODING IN SOUTHERN CALIFORNIA, S.E. Rantz, U.S.G.S.
Circular 601-B, 1970,

“Urban storm drainage criteria manual from Denver," Elmer L, Claycomb,
CIVIL ENGINEERING - ASCE, 40(7):39-41, 7/70.

URBAN STORM RUNOFF AND COMBINED SEWER OVERFLOW POLLUTION, SACRAMENTO,
CALIFORNIA, Environgenics Company for EPA, 11024 FKM, 12/71.

“Urban storm runoff relations," W. Viessman, Jr., W.R. Keating, and K.N.
Srinivasa, WATER RESOURCES RESEARCH, 6(1):275, 2/70.

"Urban stormwater quality and its impact on the receiving system,” Edward
H, Bryan, PROCEEDINGS OF THE SOUTHERN WATER RESOURCES AND POLLUTION
CONTROL CONFERENCE, 20:4/71.

VARIATION OF URBAN RUNOFF WITH DURATION AND INTENSITY OF STORMS, .D.M. Wells,
T.A., Austin, and B.C. Cook for Office of Water Resources Research, 8/71,

WATER POLLUTION ASPECTS OF STREET SURFACE CONTAMINANTS, James D, Sartor and
Gail B. Boyd for Office of Research and Monitoring, EPA, 11034 FUJ, 11/72.

WATER POLLUTION ASPECTS OF URBAN RUNOFF, APWA for FWPCA, 1/69.
WATER QUALITY CHARACTERISTICS OF STORM SEWER DISCHARGES AND COMBINED SEWER

OVERFLOWS, V. Kothandaraman, Ill, State Water Survey, Urbana, Circular 109,
1972.

c-11


Appendix A

DATA ACQUISITION AND PROCESSING FOR
CONTAMINANT LOADING RATES AND MATERIAL COMPOSITION

1, Literature Sources

The objective of this stage of the manual is to determine the rates at
which solids accumulate on street surfaces and the chemical and bio-
logical composition of those solids as they relate to land use, cli-
mate, average daily traffic, and other common parameters, The method
for achieving this objective was not to design new experiments but to
extract the necessary data from available published literature, Ac-
cordingly, the URS staff conducted a search and analysis of this lit-
erature to obtain data which would fit into an idealized data matrix

or a priori model.

Conceptually, rates of solids accumulation (loading rates) and the
compesition of the accumulated solids should vary from place to place
as a function of certain independent variables such as land use, average
daily traffic, climate, season, population density, the fraction of the
land covered by solid surfaces, the median income of the population in
the watershed, and the type of landscaping in the watershed. It is con-
ceivable that, given enough data, an equation could be written relating

the loading rate and chemical composition to each of these independent

parameters.

It became apparent quite early in the analysis of the available litera-
ture that in no single publication were all of the desired independent
parameters presented along with the loading rate and composition. Of
the several parameters which could have been included in an idealized
data matrix, relatively few were sought on a regular basis, These para-
meters are listed in Table A-1 as independent and dependent parameters.

Some of the independent parameters are represented by numerical codes.

A-1


Suberea 1

Subarea 2

IF

F

t a
‘8

1 i
%
ALi $
£

on *
3. OCS
qa 620 @

I-56

« A Hypothetical Study Area Consisting of Two Subereas

Figure 17


TI-I

Table 3. THE NATIONWIDE MEAN SOLIDS LOADING RATE AND COMPOSITION

Lbs/Curb Mi/Day Concentrations in Micrograms per Gram of.Dry Solid
Loading BOD, 5 coD OPO 4 TPO Pr NO. 3 NH, y ORGN ca Cr
156, 19,900, 140, 000,, 1,280, 2,930, 804, 2,640, 2,950, 3.4, 2i1,
——
Concentrations in Micrograms per Gram of Dry.Solid #/Gram
a
Total Fecal
cu Fe Pb Mp Ni Sr Zn Coliform Coliform

104, 22 2000, 1 »810, 418, 35, 21, 370, 2. SEG, 1. TES,

percent Standard Error of the Mean Code: 0-9, 10-19, °20-29,
439-39, 40-49, £50-62.


A quantity/quality hydrograph describes runoff flow, pollutant concen-
tration, and pollutant load as a function of time. Since it is not

feasible to treat or store extremely large amounts of runoff resulting
from exceptionally severe storms, a quantity/quality hydrograph enables

one to focus attention on the most polluted portions of the runoff.

The development of a quantity/quality hydrograph is based on the assump-
tion that runoff will remove all size particles at approximately the same
rate (i.e., the rate of contaminant removal is independent of particle
size) even though each pollutant may not be equally distributed over all
particle size ranges, This assumption permits the development of the
quantity/quality hydrograph based on total solids concentration, which
can then be multiplied by a proportionality factor to determine single
pollutant concentrations, The alternative would be to develop quantity/
quality hydrographs for each pollutant under consideration which would
not significantly increase validity but would greatly add. to the work
load, The assumption was supported by the results of the URS Research
Company study of the "Water Pollution Aspects of Street Surface Contami-

nants,"

An example of developing a pollutograph and a loadograph is given in
Example 7, Section II,


solids ranged from 1000 to 3500 mg/f., Runoff samples taken from Leningrad's
cobblestone streets in 1948-1950 contained BOD,,'s of 36 mg/f and suspended

solids of 14,541 ng/?.?

From 1945 to 1948 in Stockholm, Sweden, runoff samples were taken during sum-
mer storms,” Most of the samples were taken from streets and parks. Test
results on these water samples revealed median values of 17 mg/f BOD,,

188 mg/f COD, 300 mg/f total solids, and 4000/100 mf coliforms, Evidence

of the potential for shock pollution was revealed by individual samples
which ranged as high as 80 mg/f BOD, 3100 mg/f COD, 3000 mg/f total solids,
and 200,000/100 mf for coliforms.

One of the earliest and most often cited studies in this country was conducted
by Palmer in downtown Detroit, Michigan, in 1949.7 Water samples taken at
catch basins indicated BOD, levels on the order of 96 to 234 mg/f, 310 to 914
mg/f total solids, and coliform counts of 25,000 to 930,000 MPN/100 mf.

In 1954, runoff samples taken from a 6l1l~acre (248 ha) estate in Oxney,
England, contained BOD, "s up to 100 mg/f and suspended solids up to 2045 ne/p.4
This study also revealed that the BOD, tended to increase with the length of
the antecedent dry weather period. The pollution potential of the first flushes
of runoff was found to be not much greater than subsequent flow unless there had
been a long antecedent dry period. On comparison with a hypothetical combined
sewer system for the same area, it was concluded that the separate system re-
duced the BOD, entering the receiving stream but increased the suspended solids

load six- or sevenfold.

In 1959 and 1960, in order to determine the effect stormwater runoff was having
on the aquatic vegetation of Green Lake in Seattle, Washington, runoff samples
were taken from surrounding street gutters.°> After analyses, the runoff was
shown to contain BOD, 's of about 10 mg/f, coliforms up to 16,000 MPN/100 mf,
nitrate nitrogen to 2.80 mg/f, and soluble phosphorous to 0.78 mg/f . The

study recommended discontinuing most urban drainage to the lake.


Both an impervious area unit hydrograph and a street surface unit hydro-
graph can be modified to reflect the impervious runoff rate. This mod-
ification leads to the development of an actual hydrograph portraying
impervious runoff and another portraying street surface runoff during

a specific storm event. The actual hydrographs will be used in subse-

quent procedures.

1-47


(b) A portion of an urban watershed
‘Pac® Mee, o'

(a) An entire urban watershed

=< © watershed boundaries

(e) Two or more homogeneous portions of an urban watershed
- nF

Figure 1. Definition of a Study
I-4


Te-I

Table 9, PERCENT OF CONTAMINANTS REMOVED FROM STREET SURFACES BY RUNOFF RATE/DURATION
Ruifoff Rate Runoff Duration (hr)

(in. /hr) 0.25 0.5 1.0 2,0 3.0 4.0 5.0 6.0

O.1 10,9 20.5 36.9 60.1 74.8 84.1 90.0 >90.0

0.2 20.5 36.9 60,1 84.1 >90.0 >90.0 >90.0

0.3 29.1 49.8 74.8  >90.0

0.4 36.9 60.1 84,1

0.5 43.7 68.3 90.0

0.6 49.8 74.8  >90.0

0.7 55.3 80,0

0.8 60.1 84.1

0.9 64.5 87.4

1.0 68.3 90.0



Bioassay tests conducted in aerated, moderately hard water indicated no toxic
effects on stickleback during a 96-hour period. It was determined that the
immediate toxic effects of road surface runoff are most likely due to extreme
oxygen demand rather than to effects from heavy metals, The most dramatic
toxic effects of metals will most likely occur when runoff is discharged into

quiescent water where it is allowed to accumulate to toxic concentrations.

About two-thirds of tHe five-day BOD values was exerted during the first day
of discharge of road surface particulates into a simulated receiving water
environment, Thus, very high BOD, values can cause serious oxygen depletion

problems in the receiving water immediately following discharge.

The effect of discharge from a separate storm sewer system in Ann Arbor,
Michigan, was measured following a storm in 1964.14 The DO level in the
Huron River was depressed from about 10 mg/f to 2 mg/f. The depressed DO
level lasted about 24 hours after the end of the storm and affected the

river 2 miles below the storm sewer outfall.
4, Control Measures

A thorough discussion of control measures needed to reduce the pollution
potential of urban runoff is contained in the American Public Works Associ-
ation report 1° Tie following list is an outline of their major recommenda-

tions for effective control and reduction of runoff pollution.

1. Public cooperation -- in reducing the amounts of street litter

2. Street sweeping improvements -- for reducing accumulations of
urban street litter

3, Catch basin design and operation improvements -~ for reducing
discharges of supernatant liquids and entrained sludge

4, Roof drainage controls -- to reduce overloading of combined
sewers

5. Improved regulation and enforcement procedures -- for reducing
urban littering

y-13


It is assumed that the network of interconnected impervious surfaces can
be isolated from the study area and treated as a separate, although ir-
regular, watershed as shown in Figure 12b, Furthermore, it. is assumed
that, likewise, the street surface network can be isolated from the

study area and treated as a separate watershed as shown in Figure 12c.

Using Espey's equations, one can develop a unit hydrograph for the
watershed shown in Figure 12b by assuming that the area of the water-
shed is equal to the area of impervious surfaces (i.e., 15 acres) and
that the watershed has an imperviousness of 100 percent. The length
and slope of the main drainage channel are considered to be identical
to those of Figure 12a. This same approach can be applied toward the
development of a unit hydrograph for the watershed shown in Figure 12c,
whereby it is assumed that the area of the watershed is equal to the
area of street surfaces (i.e., 10 acres) and that the watershed has an

imperviousness of 100 percent.

At first glance, the above adaptation of Espey's equations may appear
to be a rather severe extrapolation of Espey's work, However, favorable
results can be obtained by using this approach. Figure 13 shows unit
hydrographs for the study area, impervious surface, street surface

and pervious surface runoffs. All of these, with the exception of

the pervious surface unit hydrograph, were developed by using Espey's
equations in the manner previously described, The pervious surface
unit hydrograph was developed by graphically subtracting the ordinates
of the impervious surface unit hydrograph from the ordinates of the

study area hydrograph.

A visual comparison of the unit hydrographs of Figure 13 indicates that
the unit hydrographs behave as expected. Both the impervious surface
unit hydrograph and the street surface unit hydrograph reach their
peak flow quicker and have shorter time bases than the study area unit

hydrograph. Furthermore, pervious runoff does not commence until about


3.2 Determination of Contaminant Loading Rates and Materials Composition

The following material presents procedures and data by which a user may
predict the rates of solid accumulation on urban streets and the composi-
tion of those solids, These data are based on an analysis of existing
published data. The procedures used in the acquisition and processing of
available data are described in detail in Appendix A. However, this sec-
tion as presented is complete and can be used directly by the user to ob-
tain the desired predictions, Appendix B describes recommended sampling
procedures if the user desires to substitute actual source data for the

data given in this chapter.

3.2,1 Use of the Tables

The basic tables consist of mean loading rates and solids composition in
the set of all data and in 19 subsets of the whole set. The original
basic statistics are shown in Appendix A/Table A-23. These statistics
are condensed into Appendix A/Table A-24 from which the loading and com-

position tables of this section are derived.

The loading rates are expressed as pounds per curb mile per day (lb/curb
mi/day), whereas later procedures make use of loads in terms of total
pounds per acre of street surface. Therefore, it will be necessary for
the user to initially convert the loading rate to load/curb mi, and then

to convert load/curb mi to load/acre of street surface before proceeding to

the following sections,

Compute the load/curb mi by the following steps:
1. Calculate the load in 1b/curb mi as

Solids Load = Rate of Accumulation X
Equivalent Days of Accumulation


Section V

STATE OF THE ART


g-II

Table 11. SAMPLE ROW OF LOADING AND COMPOSITION DATA

Lbs/Curb Mi/Day

Concentrations in Micrograms per

Gram of Dry Solid

Loading BOD, coD OPO 4 TPO 4 NO, NH mn ORGN cD CR
30" 19,900 140,000 1,280 2,930 804 2,640 2,950 3.4 211
—_
Concentrations in Micrograms per Gram of Dry Solid #/Gram
——
cu FE PB MN NI SR ZN TCOLI FCOLI
* * * * *
104 34,500 1,810 418 35 10 480 6,8E5 1.184

Note: Substitutions are indicated by an asterisk,


or-v

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DURHAM
DURHAM
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CINCINNATI
CINCINNATI
CINCINNATI
CINCINNATI
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ANN ARBOR
ANN ARBBR
APN ARBOR

CINCINNATI
ANN. ARBBR
CHICAGS
cHICAGS
cHIcace
curcacs
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CHICAGO
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CHICAS.
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PHOENIX I

SEATTLE.
LOW/OLD/SING
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ENTIRE MATRIX OF AVAILABLE DATA

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surface via other impervious surfaces) cannot be ignored. These non-
street interconnected impervious areas will contribute a significant
amount of runoff, even during storms of short duration. However, since
contaminant loadings are provided only for street surfaces and, more-
over, since street surfaces have peen shown to be the primary pollutant
contributor, the assessment of urban runoff developed in this manual
will consider runoff from non-street impervious area as being unpolluted

and merely acting as dilution water.

For a more accurate assessment of pollutant concentrations, samples of
runoff from non-street impervious areas can be obtained and analyzed.
Samples should be taken from a point where runoff flows into the street,
as early in the storm event as possible after runoff begins to flow.

The impervious area could then be considered as a street surface and the
pollutant load determined from the samples converted from an aerial ba-
sis to curb mile basis (Table 2).

4.2 Determination of Volume of Runoff

An approximate assessment of urban runoff pollution requires a knowledge

of (1) the volume of runoff from impervious surfaces within a selected
study area during a given storm event, and (2) the amount of street sur-
face contaminants removed by runoff. Accordingly, the total volume of
impervious runoff from a study area may be estimated by the following

equation:

Volume of Runoff (cf)* = [Runoff Rate (in, /hr)] x [interconnected
Impervious Area (acres)] x i, 815]

* Equation is applicable for a 30-minute runoff duration.

I-28


Section II

EXAMPLE PROBLEMS


First, the days since rain had fallen or the street had been swept were

transformed into equivalent days of accumulation (EDA) by the formula

EDA = (days since last rain - days since last swept)

X (1 - sweeping efficiency) + days since last swept

The assumption inherent in this formula is that the last rain cleaned the
street thoroughly. This is a poor assumption, but no data were available
from which to estimate the fraction of material washed off by each rain.
Generally, it is assumed that a rain intensity of 0.5 inch/hour gets 90
percent of the solids, The days since last rain figure is the days

since a rain of this intensity. Obviously, whenever rain had fallen
fewer days previous than the street had heen swept, the days since last

rain was EDA.

Attempts were made to fit EDA and load data by linear regression, poly-
nomial regression, and a theortical curve. To remove the effects of
different land use and climate, the data were separated wherever there
were enough data records to allow it. No statistically significant
relationships could be found between EDA and load in any land use or
climatic category. To include potential effects of ADT on the load, these
data were included as log ADT and log (ADT x EDA) in a second attempt

to find relationships, Attempts were.made to fit load with log ADT and
log (ADT x EDA) by linear and polynomial regression and with a theoret-
ical curve. No significant relationships were observed. The best cor-~
relation coefficient obtained was 0.29. This was obtained with a linear
regression between load and log (ADT x EDA) in residential areas in the
east, and suggested that load decreased with increasing log (ADT x EDA).

After this abortive attempt to verify the theoretical relationship with
data from the real world, the loading data was transformed as usual into
the ratio Load/EDA and expressed as pounds per curb mile per day. The
results of this preliminary attempt to extract information from data

taken from the real world is indicative of the complexity of real systems,

A-14


“Characterization, treatment, and disposal of urban stormwater," S.R. Weibel,
R.B. Weidner, A.G, Christianson, and R.J, Anderson, PROCEEDINGS, 3RD
INTERNATIONAL CONFERENCE ON WATER POLLUTION RESEARCH, Munich, 1:1966.

"Chemical and physical comparison of combined and separate sewer discharges,"
R.J, Burm, D.F. Krawczyk, and G.L, Harlow, JOURNAL WPCF, 40(1):112-126,
1/68.

CHEMICAL TREATMENT OF COMBINED SEWER OVERFLOWS; Study of flocculent treatment
and disinfection of Milk River Pumping Station combined sewer overflows at
Grosse Pointe Woods, Michigan, Dow Chemical Co. for Water Quality Office,
EPA, 9/70.

CHOICE OF ADJUSTMENT TO FLOODS, Gilbert F. White and John Eric Edinger, U. of
Chicago, Dept. of Geography, Res. Pap. No. 93, 1964,

COMBINED SEWER OVERFLOW ABATEMENT ALTERNATIVES, WASHINGTON, D.C., Roy F.
Weston, Inc. for Water Quality Office, EPA, 8/70.

COMBINED SEWER OVERFLOW ABATEMENT TECHNOLOGY; A compilation of papers
presented at the FWQA "Symposium on Storm and Combined Sewer Overflows,"
Chicago, 1970,

COMBINED SEWER OVERFLOW SEMINAR PAPERS, FWPCA, Storm and Combined Sewer
Pollution Control Branch, 11/69,

COMBINED SEWER OVERFLOW STUDY FOR THE HUDSON RIVER CONFERENCE, Alen I.
Mytelka, L.P. Cagliostro, D.J. Deutsch, and C.A. Haupt, EPA-R2-73~-152,
1/73.

"The combined sewer problem and standards of water quality," Gordon McCallum
and Leo Weaver, SUMMARY OF PROCEEDINGS, INTERSTATE CONFERENCE ON WATER
PROBLEMS, Dayton, Ohio, 12/65,

COMBINED SEWER TEMPORARY UNDERWATER STORAGE FACILITY, Melpar for FWQA, 10/70.

"Combined wastewater overflows," C.K, Chen and W.W. Saxton, JOURNAL WPCF,
45:434, 1973.

COMMUNITY ACTION GUIDEBOOK FOR SOIL EROSION AND SEDIMENT CONTROL, M.D, Powell,
W.C, Winter, and W.P, Bodwitch, National Assoc. of Counties Research
Foundation, 3/70.

“Computer simulation of urban storm water runoff," Carl W. Chen and Robert P.
Shubinski, JOURNAL HYDRAULICS DIVISION, ASCE, HY2:7924, 2/71.

"Conservation programs in the urban fringe," John W. Neuberger, JOURNAL OF
SOIL AND WATER CONSERVATION, 216, 11-12/69,


m,

Oe

Pe

qa.

Not significantly different with landscaping type

Not significantly different between street surface types

Heavy industry areas, low also in residential areas; this

The northeast (highest in the northwest); this may reflect

4.
5.
Lead Concentrations Are Lowest in:
1.
probably reflects low vehicular traffic
¥2,
the inhomogeneity of sampling sites
3. Areas with light and moderate traffic
4, Areas with grass landscaping
5. Concrete road surfaces

Manganese Concentrations Do Not Vary Greatly Between Categories

Nickel Concentrations Are Lowest in:

Residential areas

The northeast and southeast

Areas with moderate traffic (500-5000 ADT)
Areas with grass landscaping

Concrete road surfaces

Strontium Concentrations Vary Only Slightly Between Categories

Zinc Concentrations Are Lowest in:

*1.

Heavy industry areas

The northeast

Areas with light daily traffic {500 ADT)

Not significantly different between landscaping types

Concrete surfaces

A-40"


Cubic Feet per Second

25-4

20-4

2 Inches per Hour

# Inch per Hour

Time ——___»

Figure 14, Modification of Unit Hydrograph
to Reflect a Specific Runoff Rate

1-46


Section II
EXAMPLE PROBLEMS

The example problems presented in this section will assist the user in

determining the water pollution aspects of urban runoff,

The following lists the example problems presented in this section:

Example 1: Characterization of a study area
Example 2: Determination of contaminant loading

Example 3: Determination of runoff rate by runoff
coefficient

Example 4: Determination of runoff rate by composite
runoff coefficient

Example 5: Selection of storm event

Example 6: Development of a unit hydrograph

Example 7: Development of a pollutograph and loadograph
Example 8: Utilization of routing technique

Example 9: A Level I assessment of urban runoff

Example 10: A Level II assessment of urban runoff

EXAMPLE 1

A 27-acre urban watershed is defined as a study area as shown in

Figure 21, Determine the following study area characteristics:

e Average Imperviousness
e Length of Main Drainage Channel

° Average Slope of Main Drainage Channel


B, SOURCE ABATEMENT

Although the accumulation of a certain amount of street surface contam-
inants in an urban environment is inevitable (e.g., pavement wear, dirt,
grease and oil from the undersides of motor vehicles), much of the
litter that reaches the street surface can be eliminated, or at least
effectively controlled at its source, This direct approach to reducing
the runoff pollution potential can best be accomplished through active
public education and through effective and enforceable regulations and :

ordinances relating to street cleanliness.

In order to gain public support and cooperation in reducing street
litter, an effective education program is necessary to inform the public
of all the ramifications of street litter, including its effect on water
pollution. This information can be presented in well-organized school
programs; press, radio, and television messages; and lectures to local
civic organizations, A list of regulations and ordinances, possibly in
leaflet form, that pertain to litter control should be available so
that all citizens may understand what is expected of them, This list
or digest should be printed in all appropriate languages of the commu-
nity.

The local government can do its part by providing an adequate number and
variety of litter containers and by setting a good example. Litter con-
tainers should be kept in a presentable condition and should be emptied
frequently, Strict cleanliness practices should be followed by city
waste collection forces and other city departments which generate litter.
Street sweeping and sanitation equipment should be kept in attractive

condition to encourage community pride and respect.
Well-publicized cleanup campaigns can also provide motivation for the

public to clean up the premises and dispose of accumulated trash. In
many cities, spring cleanup days, in which free pickup of bulky refuse

Iv-2


Table A-24, MEANS AND PERCENT STANDARD ERRORS OF THE MEANS (Subseripts*)
OF THE SET OF ALL DATA AND OF 19 SUBSETS OF THE DATA

‘1be/curd
ni/de Concentrations in micrograms per gram of dry solid —e,/eren
Category Loading” 300, coo a as «CMe con eo Poissons? rout
Land Use 10 Open space 12 20,300 171,000 1,700 5,440 16,000 7,250 0.6 $ 9 2,600 15 6 22° 1.685 7.253
20 Residential 149, 14,000, 82,000, 850, 2,000, 550, 660 1,800, 3.0, 192, 93, 20,600, 1,490, 302, 28, 21, 350 1.76, 1.665,
30 Commercial 74, 8,700, 269,000, 2,250, 4,850 1,580, 9,620, 6,430, 4.2, 225, 193, 23,200, 3,440, 397, 48, 18, 520, 1.956, 1.985,
40 Light industry 389, 27,300 180,000 1,275 430 1,750 4.0, 2884 128, 21,800, 2,780, 490, 414 27 968, 2,185, 1.585,
80 Heavy industry 203, «12,100, 88,000, 1,250, 246, 1,420, 9.9, 278, 107, 28,600, 1,160, 570, 37, 23, 317, 8.265, 1.855,
Clinate 1 Northes 291, 29,100, 159,000, 9904 3,390, 1,010, 2,640, 5,970, 2.6, 139, 99, 17,700, 870, 363, 21, 27, 260, 1.856, 4,485,
2 Southeast 103, 29,100, 172,000, 2,240, 212 43 1,970, 4.0, 234, 137, 20,300, 1,370, 395, 21, 28, 499, 1.956. 7.054,
4 Southwest 50, 12,700, 139,000, 470, 21,1604 2,400, 3.8, 241, 78, 22,600, 2,520, 446, 57, 15, 957, 5.7E54* 5.285,
3 Northwest 30, 10,000 38,000 1,100 59 2,000 1.8, 246, 96, 34,500, 2,600, 455, 95, 10, 480, 6.8E5, 1, 1E4y
> Average Dotty < 500 280, 21,600 153,000 1,500 5,440 8,330 5,470 2.8, 198, 89, 21,700, 1,210, 384, 26, 19, 252, 1.956, 6.984,
Novaey 500 - 5,000 140, 9,500, 89,000, 7934, 212419, 1,518, 18,900, 1,060, 415, 17, 37, 418, 2.286, 3.4554
5,000 - 15,000 146, 27,400, 163,000, 1,340, 2,980, 896, 2,640, 2,900, j, 22,500, 2,010, 442, 38, 18. 375, 3.186, 1,785,
> 15,000 82, 5,720 26,980 S14 501 2,600 22,900, 2,290, 357, 28, 18, 389, 3.855, 1.485,
‘Type of Land- 1 Gra 196, $2,400, 154,000, 1,720, 3,500 1,010, 3,620, 3,900, 9.9, 197, 96, 21,000, 1,370, 408, 27, 24, 348, 8.955, 7.484,
scaping
Beyond’the 2 TFS 43, 23,000, 142,000, 1,140, 540, 1,800, Lie, 9.585,
Sidewalk 3 Landscaped
buildings 93, 9,990, 88,900, 24, 721, 2,600 4.4 242 120 34,500 2,350 430, 33 22 «552 S.SE6, - 3.585,
4 Hard surfaces 121, 13,700, 78,000, 787, 2,510 461, 662-:1,200, 3.6, 228, 116, 22,000, 2,370, 446, 41, 16, 385, 7.165, 1.6854
Street Surface 1 Asphalt 150, 23,000, 150,000, 2,470, 212, 11,600 1,770, 3.7, 217, 107, 22,400, 2,000, 414, 43, 18, 380
Material 2 Concrete 38, 72,000, 383,000 3,520, 5,180 2,600, 3,620, 6,680, 3.5, 173, 97, 22,800, 1,280, 342, 24, 45, 292,
All data 19,900, 140,000, 1,280, 2,930, 804, 2,640, 2,950, 3.4, 211, 104, 22,000, 1,810, 418, 25, 21, 370, 2.586. 1.785,

“percent Standard Error of the Mean Subscripting Code: a = 0-9, b= 10-19, ¢ = 20 ~ 29, d = 30 - 39, © = 40 ~ 49, f = 50 ~ 62,
Xcolttorn counts are expressed in conputer notation, 1.0., E5 = 10°,


property where the litter occurs, This approach is common in many
European towns, where each storeowner or homeowner is responsible for

maintaining the sidewalk and curb fronting his property.

A major problem of litter control in most of the larger cities is parked
or abandoned cars. Parked cars make it impossible for street cleaning
equipment to clean all of the street, Part of this problem can be
solved by parking regulations which prohibit parking in certain areas
during specific hours. In residential areas, these parking restrictions
may apply only once or twice a week, while im commercial areas they

may apply every day.

The problem of abandoned cars is much more difficult to control, par-
ticularly in the very large cities. Abandoned autos not only interfere
with street cleaning operations but are a source of street litter.
Abandoned autos should be removed from the streets as soon as possible,
either by city forces or by a private contractor hired by the city.

The sale or auction of operative vehicles, and possibly the sale of
parts from a city-owned and operated junk yard, could help defer the

cost of removal.

Regulations should also be established that limit the use of chemicals
commonly used in the urban environment for weed and pest control.
Since the city is usually responsible for the use of large amounts of

these chemicals, regulations should be relatively easy to enforce,

Iv-5


Table 6. NINETY PERCENT CONFIDENCE LEVEL®

Lba/curd
mi/day Concentratiois in micrograms per gran of dry solid z :
Category Loading BOD, COD OPO, “TPO, XOy My Oren Ca Cr cu Fe ‘Pb tin NT Sr an TOOLI FOOLT
Land Use 10 Open space
20 Residential 82,000, 850, 1,800,
30 Comercial 74, $8,700, 269,000, 1,580, 6,430, 3,440, 520,
40 Light industry
50 Heavy industry 1,160, 8.265,
Clinate 1 Northeast 5,970, 2.6, 70, 363, 21 260, 448s,
by 2 38, > e
2 Southeast 103, 2,240, 1,970, 1,370, 21, 7.084,
4 Southwest 50, 470, 241, 78, 2,520, 57, 15,
5. Northwest 30, 246, 34,500, 2,600, 10, 480, 6.865, 1. 1EMy
Average Detly << 500 252,
wrereie 500 ~ 3,000 9,500, 83,000, a9, 18,900, 1,060 17, . 3.4854
No. /4ay . 2 7800, $3,000, b +900, 1,060, ‘a -
5,000 - 15,000 18,
> 15,000 82, 357, 3. BES,
A a
‘Type of Land- 1 Grass 1,370, 8.955, 7.454,
wcaping
Beyond the 2 Trees 8, V1E7,
Sidewalk 3 Landscaped
buildings 93,
4 Hard surfaces 78,000, 790, “1, 16, 7.1FS,
Street Surface 1 Asphalt 2,470, 1,770, 18
Material 72,000, 3 520, 2,600, 6,680, 1,280 4s
Concrete 1000, 15204, 7600 7080 12800 c
All data 156, 19,900, 140,000, 1,280, 2,990, 804, 2,640, 2,950, 3.4, 211, 104, 22,000, 1,810, 418, 35, 21, 370, 2.556, 1.785,

"only those subset meana are show which differ from the means of the set of all data at the 90-percent confidence level (Student t > 1,80, Degreea of Freedom z 10). Total
number of permitted substitutions = 74, Percent Standard Error of the Mean Subscripting Code: © = 0-9, t = 10-19, c= 20 - 29, d= 30- 39, e = 40 ~ 49, f = 50 - 62.

cont tora counts are expressed in computer notation, i.e., ES = 105,

Note: Prelimiaary decisions to include of exclude values made on the basis of Table C-6, “All values included were reaffirmed by checking the original data, In this check,
values were excluded 1£ n < 10 and the diversity of the sample by the other independent paraneters was small, e.g., if ell loadings for < 500 ADT cane from Baltinore.
Climate 6 was rejected because it is redundant to the Grand Mean.



An analysis of street surface contaminants found on rural roads and highways
indicated that the city street particulates have a greater pollution poten-
tial on a strength (mg/kg) basis. The BOD, strength of city samples was
found to be an order of magnitude greater than the rural samples. The heavy
metal contents of airport surfaces were found to be quite similar to road

surface particulates,

Grease and oil were found to be the major organic constituents of the street
particulates, but no definite correlation was established between organic

strengths (mg/kg) and land use,

Highway deicing compounds were discussed as a source of urban runoff pol-
lution in an EPA report prepared by Edison Water Quality Laboratory in 1971.23
High concentrations of highway deicing salts were shown to be common in urban
runoff waters during periods of snow melt, Concentrations of chlorides as
high as 25,000 mg/f have been found in street surface drainage, and up to

2720 mg/f in storm sewers. Surface streams in urban areas also have been
found to contain up to 2730 mg/f chlorides. The adverse impacts that deicing
salts have on small lakes and streams have been documented, but their influence
on major U.S. rivers appears,-at this time, to be relatively minor, Neverthe-
less, it is recognized that there are inadequate surveillance data available

to clearly define this area, and more information is necessary.

Deicing compounds often contain special additives with severe latent toxic
properties. Complex cyanides and chromate compounds used as additives have
been found in storm sewers, However, little is known of their fate and dis-

position or of their effects on the environment,

3. Impact of Urban Runoff on Receiving Waters

In a recently completed EPA stuay, 2” copper, cadmium, lead and zinc contained
in street surface runoff were found to be sufficiently soluble to cause toxic
effects to certain aquatic organisms under selected conditions (such as soft

water).

v-12


LI-V

cry

GRAND RAPIDS
CINCINNATI
‘TULSA

10
40

37
at

5600

ms RS MK LOAD pops

Table A~6.

12

con oPOs«TPOA OSG

22300 25200

2000 8940 $6000 128
18200 90900 471

LAND USE 10 - OPEN SPACE

100
00

on6

5

9

cna RB

2600

a
15

TM
6

mom
ee

SES 86989
SoNES Ge9E3


TABLES

Number

© eA

10
11
12
13

14

A-6
A-7
A-8
A-9

Characteristics of Stormwater Runoff... .

Typical Curb Mile Densities Arranged by
Land Use Types. . 2. 1 1 1 ee ew ee ee

The Nationwide Mean Solids Loading Rate
and Composition... .. 1... 2.2 ee ee

Mean Concentrations of Mercury and
Chlorinated Hydrocarbons in Street Dirt
from Nine U.S, Cities... 1... ee eee

Ninety-Five Percent Confidence Level. ...
Ninety Percent Confidence Level ......
Eighty Percent Confidence Level ......
Values of the Runoff Coefficient k.....

Percent of Contaminants Removed from Urban
Land Surfaces by Runoff Rate/Duration . ..

Lag Time Adjustment Factors ......e6
Sample Row of Loading and Composition Data.
Average Street Sweeper Removal Efficiency .

Parameters Which Affect Street Sweeping
Performance . . 1. 6 6 es se ee ee eee

Nationwide Estimates of Particulate

Emissions, 1970... 2 6 1 ee ee eee
Data Acquired for the Analysis. .....
Codes for Independent Variables ......
Climatological Categories .....

Entire Matrix of Available Data.....

Mean Chlorinated Hydrocarbon and Mercury
Concentrations in Urban Street Dirt from
Several U.S, Cities (The URS I Study) ...

Land Use 10 - Open Space, ... 2... ees
Land Use 20 - Residential. .......
Land Use 30 - Commercial, . .... 2 eee

Land Use 40 - Light Industry. .......

XI

Page

I-10

I-11
I-11

I-13
I-14
I-15
I-16
I-19

I-21

1-59
TI-5
IV-6

Iv-9

IV-13
A-2
A-4

A-10

A-12
A-17
A-18
A-19
A-19


Appendix B
SAMPLING PROCEDURE

In many instances, local agencies may want to conduct sampling and ana-
lytical programs of their own. These data, if handled properly, may be
used in analyzing the areas’ runoff problems instead of using values

presented in the manual, This would be desirable in most instances, but
especially in areas or under specific conditions that were not analyzed

in great detail under any studies used in preparing this manual,

Additional information is presented in the following discussion to help
these local agencies design and carry out sampling programs of their own.
The first question to be answered concerns the type of sampling to be
conducted. Two general types have been used in the studies referenced
in this manual, These are the street surface collection method and the
runoff collection method. Both methods require a substantial amount of
additional information concerning the area, The street surface method
has an advantage of being able to conduct sampling without having to
wait for rain and the elaborate rainfall data required for the runoff

sampling method,

The following list briefly describes the procedures which may be used in

a street surface sampling program,

LOCALITY DATA COLLECTION

After setting up traffic control in the chosen test area, information
should be gathered as to: location, date, land use, parking and traffic
characteristics; street, gutter, and curb composition, condition and
texture; test area and description of the adjoining area, At this time
photographs of the area should be taken, Street cleaning and rainfall
history of the test site is highly desirable.


Dissolved air flotation has been shown to be a rapid and rather effective
technique for removing solids. In addition, organic removal has been
rather high for a physical treatment process. In tests, this process
has effectively removed approximately 40 percent of the organics and 60
percent of the solids from a combined sewer overflow under a surface
loading rate of 900 cu m/min/ha (3200 gpd/sq ft). The addition of

about 25 mg/f of chemical flocculate increased these removal efficiencies
by 30 percent, Probably the main drawback of the dissolved air flotation
process at the present time is the high cost. Construction costs of
$800/f/sec ($35,000/mgd) have been reported. However, a treatment

system for combined overflow and separate stormwater runoff in
Sacramento, California, which included dissolved air flotation was
determined to be the least-cost design. Capital costs for this proj-

ect were $530,000/P/sec ($12,000/mgd), and operating costs were esti-
mated at $6.87 per 1,000 f ($26/1,000 gal).

a. Screening

A variety of screening techniques have been effective as primary treat-
ment processes, Ultrafine screens, rotary fine screens, and hydraulic
sieves are usually used as pretreatment units. The rotary fine screen
requires only one-tenth to one-twentieth the land use normally required
for primary treatment (sedimentation or flotation). Costs for rotary
screening have been reported at 5.8¢ per 1,000 f (22¢/1,000 gal) for a
1,100 f/sec (25 mgd) facility (including debt service).

Ultrafine screens and microstrainers are generally used as main treat-
ment and/or polishing devices in stormwater treatment. These techniques
can remove from 10 to 70 percent of the organic material and 25 to 90
percent of the suspended solids in wastewater, depending on the size of
the screen, the loading rates, and the character of the wastewater,
Although ultrafine screens and microstrainers are rather effective in

the removal of suspended solids in stormwater runoff, additional studies

Iv-20


In 1961, surface runoff from residential and recreational areas in Pretoria,
South Atrica,® was sampled revealing the following results: 30 mg/f BOD,,
29 mg/f COD, 228 mg/f dissolved solids, 5.4 mg/f total organic nitrogen,
and coliform counts of 240,000/100 mf, Analyses of runoff samples from
nearby commercial areas revealed slightly lower figures for all of the

above parameters except BOD,, which was found to be slightly greater.

A more comprehensive study on the quality of stormwater runoff was conducted
by Weibel et al. between 1962 and 1964,7 Water samples taken from a separate
storm sewer system draining 27 acres (11 ha) of residential and light-commer-
cial urban land in Cincinnati, Ohio, revealed the following constituent aver-
ages: 227 mg/f suspended solids, 57 mg/f volatile suspended solids, 111 mg/f
COD, 17 mg/f BOD, , 1.0 mg/f inorganic nitrogen, 1.1 mg/f total hydrolyzable
phosphate, and 1.7 mg/f organic chlorine, The average coliform density in
90 percent of the samples was 2900/100 mf, but individual samples varied
widely.

The BOD, and COD figures were, on the average, comparable to typical secondary
sewage treatment effluent, while suspended solids concentrations were gener-
ally comparable to raw sewage. The above-mentioned nutrient concentrations
exceeded the 0.3 mg/f inorganic nitrogen and 0.03 mg/f inorganic phosphate
indicated as threshold levels for algal blooms, The coliform density con-
siderably exceeded the criterion of 1000/100 mf commonly used as a maximum

for swimming waters in the United States. A further comparison of surface

runoff to domestic sewage is shown on the following page.


The loading intensities (1b/curb mile) of street surface contaminants,
expressed as weighted average values for all samples, were found to be as
follows: total solids, 1400 1b/curb mile; volatile solids, 100 1b/curb
mile; BOD; 13.5 1b/curb mile; COD, 95 1b/curb mile; phosphates, 1,1 1b/
curb mile; nitrates, 0.094 1b/curb mile; Kjeldahl nitrogen, 2.2 1b/curb
mile; total coliforms, 99 x 10°/curb mile; and fecal coliforms, 5,6 x
10°/curb mile. Substantial quantities of organic pesticides were found
in most samples, The total amount for the cities tested was 0.001 1b/
curb mile, However, the amounts varied considerably from site to site.
Both chlorinated hydrocarbons and polychlorinated biphenyl compounds (PCB)
were found rather consistently. Significant amounts of heavy metals were
also detected. Zinc and lead were the most prevalent, measuring 0.65 and

0.20 1lb/curb mile respectively,

Because of the consistent presence of heavy metals in amounts large enough
to interfere with BOD, measurements, COD tests were considered to provide
a better basis for estimating the oxygen demand potential of street sur-

face contaminants.

A sizable percentage of the pollution potential of street debris was found
to be contained in the very fine silt-like fraction (< 43 y). Although

this material accounted for only 5.9 percent, by weight, of the total solids
in street surface, it contained approximately one-fourth of the total oxygen
demand and perhaps one-third to one-half of the algal nutrients. This
material also accounted: for more than half of the heavy metals and nearly
three-fourths of the total pesticides, These concentrations of pollutants
in the very fine material are of particular importance because conventional

street sweeping operations are rather ineffective in removing this material.

The quantity or loading intensity of material at a given test site was
found to be dependent on a number of factors, including surrounding land
use, elapsed time since the last sweeping or rainfall, volume and character

of local traffic, condition and type of street surface, season of the year,


Cubic Feet per Second ———

Sample Study Area With
Hypothetical Drainage Pattern

Assumed Main Drainage
Channel if There Is A
Defined Channel

\
\

Assumed Main Drainage
Channel If Flow Is
Along Streets And
Gutters

=

~ Monitoring Location

(Location through which all flow
from the study area passes.)

Tine ——____y»

Figure 5. Sample Study Area and Corresponding Hydrograph

I-30


located. Accurate distribution of rainfall intensity is also required,

Street cleaning and rainfall history of the area is highly desirable,
SAMPLE COLLECTION

Sample collection should begin at the onset of a rain event and continue
for as long as practicable (at least several hours), Accuracy would be
enhanced by collecting discrete samples based on volume of flow and not
by time. Besides collecting samples, flow data should be compiled. If
pesticide analyses are to be conducted, the sample containers should be

glass.
SAMPLE HANDLING AND PREPARATION PROCEDURES

All solids and liquid samples should be immediately shipped from the test
sites to the laboratory. Upon receiving the shipment, the samples must
be placed in a cold room maintained at 5°C, The solids can be stored in
new unlined metal paint cans, while the liquids can be stored it plastic
containers, All samples designated for pesticide analysis must be col-

lected and stored in glass containers,

All individual solid samples should be dried under heat lamps (less than
100°F) and weighed.

Size classification of solid samples is performed by standard sieve anal-
ysis. The dried solid sample to be analyzed is placed on top of the
2000-micron screen in the nest of 5 screens (sizes 2000 microns, 840 mi-
crons, 246 microns, 104 microns, 43 microns and the pan), The screens
are then placed in a roto tap unit and agitated for a half hour, The

screens are then removed and the material on each screen weighed,

B-3


42,

43,

44,

45,

46.

47,

URBAN RUNOFF, M.B. McPherson, ASCE Urban Water Resources Research Program
Tech, Mem, No. 18, 8/72,

URBAN RUNOFF IN LAKE COUNTY, ILLINOIS: A REASSESSMENT OF THE ROLE OF
URBAN RUNOFF IN THE POLLUTION OF LAKE MICHIGAN, State of Illinois, Lake
Michigan, and Adjoining Land Study Commission Rept. of the Governor and
the 77th General Assembly, Vol, II, 10/71.

"Urban storm runoff relations," W. Viessman, Jr., W.R. Keating, and K.N.
Srinivasa, WATER RESOURCES RESEARCH, 6(1):275, 2/70.

WATER POLLUTION ASPECTS OF STREET SURFACE CONTAMINANTS, James D, Sartor
and Gail B, Boyd, URS Research Company for Office of Research and
Monitoring, EPA, 11034 FUJ, 11/72,

WATER POLLUTION ASPECTS OF URBAN RUNOFF, APWA for FWPCA, 1/69.

WATER QUALITY CHARACTERISTICS OF STORM SEWER DISCHARGES AND COMBINED

SEWER OVERFLOWS, V. Kothandaraman, I11. State Water Survey, Urbana,
Circular 109, 1972,

C-16


FIGURES
(Continued)

Number

21
22
23

25

26

27
28
29

30

31
32
33
34
35

A-1

Sample Study Area for Example 1

Unit Hydrographs Developed in Example 6. .

Pollutograph and Teadograph Developed in
Example 7. . 6... 2 we .

Study Area of Example 8. . .

Quantity/Quality Hydrographs for Subareas of

Example 8... ... 4. Be ee ee ee
Composite Quantity/Quality Hydrograph
of Example 8... 1. 6. 1 se ee eee one

Unit Hydrographs Developed in Example 10. .
Hydrographs Developed in Example 10. .....
Pollutograph and toadograph Developed in

Example 10... . . ey
Quantity/Quality Hydrograph Developed in
Example 10... . Ps

Removal Effectiveness with Number of Passes. .
The Effect of Pattern on Residual Debris...
Debris Pickup vs Brush Sweeper ........

The Effect of Sweeper Speed on Residual Debris .

Comparison of Cleaning Performance of Motorized

Street Sweeping and Motorized Street Flushing.

Climate Zone Codes for the Data Matrix and
Cities for Which Data Are Available. .....

Page
11-2
II-10

II-13
II-15

II-16

11-18
II-23
I-24

11-27

11-28
Iv-8

Iv-10
Iv-10
Iv-10

Iv-11


1000:

Average Total Solids Concentration of Runoff

A 2 3 4 5

Total Inches of Runoff
or tT T TF T T T ~~
10 20 30 40 50 60 70 80 90

. Percent of Contaminant Removal
Figure 3, Runoff Concentration as a Function of Runoff (based upon an ini~
tial contaminant loading of 100 lbs/acre of street surface)
I-24


Section IV

TREATMENT, ABATEMENT, AND DISPOSAL OF URBAN RUNOFF

A, EVALUATION OF URBAN RUNOFF QUALITY

In order to determine the significance of non-point water pollution
originating from an urban study area, the user must evaluate the results
of his assessment of urban runoff conducted in Section I, Theoretically,
this evaluation should consist of comparing predicted pollutant concentra-
tions and loads against local, state, and federal water quality standards.
Unfortunately, standards which are directly applicable to the discharge
of urban storm water runoff into receiving waters are still in the develop-

mental stage and therefore, have not been established.

Consequently, the user may substitute standards which are applicable
to effluent discharges from point sources (i.e., sewage treatment plants,
industrial sources, etc.). Alternatively, the user may supply his own
criteria for evaluation until applicable standards are enacted. Such
criteria could be based upon the ambient water quality and pollutant assim-

ilation characteristics of a particular receiving water.

Based upon the evaluation, the user can determine if treatment, abate-
ment, or an alternative method of disposal is required. The following
material is intended to provide a basic insight into the alternatives
regarding treatment, abatement, and disposal of urban runoff. It is not
intended to serve as design criteria nor as an absolute source of informa-

tion on the subject.

Iv-1


“Environmental effects of highways," Melvin E, Scheidt, JOURNAL SANITARY
ENGINEERING DIVISION, ASCE, SA5:17, 10/67.

ENVIRONMENTAL IMPACT OF HIGHWAY DEICING, Edison Water Quality Lab for Water
Quality Research, EPA, 11040 GKK, 6/71.

ENVIRONMENTAL IMPACT OF URBANIZATION ON THE FOOTHILL & MOUNTAINOUS LANDS
OF CALIFORNIA, California Div. of Soil Conservation, 11/71.

EROSION AND SEDIMENT CONTROL ON URBAN AND CONSTRUCTION SITES; An annotated
bibliography, ASAE Pollution by Sediment Committee (SW-224) of the Soil
and Water Div., 1972,

"Erosion rates and control methods on highway cuts," E.G. Diseker and E.C.
Richardson, TRANSACTIONS OF THE ASAE, 153, 1962,

"Erosion, runoff and revegetation of denuded construction sites," L.D. Meyer,
W.H, Wischmeier, and W.H. Daniel, TRANSACTIONS OF THE ASAE, 14(1):138~141,
1971,

EVALUATION OF STORM STANDBY TANKS, COLUMBUS, OHIO, Dodson, Kinney and
Lindblom for Water Quality Office, EPA, 11020 FAL, 3/71.

"Experience with the evaluation of urban effects for drainage design,”

Donald Vansickle, EFFECTS OF WATERSHED CHANGES ON STREAMFLOW, ed. by

Walter L, Moore and Carl W. Morgan, Center for Research in Water

Resources,

"Firestone installs pollution control," OIL AND GAS JOURNAL, 68(35):79,
8/31/70,

"Five cities try to stop storm pollution," ENGINEERING NEWS-RECORD, 67,
1966,

“Freeway runoff to be treated," PUBLIC WORKS, 102(5):104, 5/71.

"Graphic analysis of roadway runoff," J.B, Wolfson, CIVIL ENGINEERING - ASCE,
64-65, 6/71.

GUIDELINES FOR EROSION AND SEDIMENT CONTROL PLANNING AND IMPLEMENTATION,
Maryland Dept. Water Resources and Hittman Associates for Office of Research
and Monitoring, EPA, R2-72-015, 8/72,

HIGH RATE FILTRATION OF COMBINED. SEWER OVERFLOWS, Hydrotechnic Corp. for
Office of Research and Monitoring, EPA, 11023 EYI, 4/72.

"Hydraulics of runoff from developed surfaces," Carl F, Izzard, PROCEEDINGS
OF THE 26TH ANNUAL MEETING, HIGHWAY RESEARCH BOARD, 12/46,


2.0 DEFINITION OF A STUDY AREA

The basis for defining a study area will vary according to the require-

ments of the user. One may assess the water quality of urban runoff ori-

ginating from an urban development, an urban watershed, or an entire ur-

ban community.

A study area may be defined as follows:

q@)
(2)
(3)

(4)

(5)

An entire urban watershed (Figure la).
A portion of an urban watershed (Figure 1b).

Two or more entire urban watersheds (Figure 1c).
Each individual watershed would be defined as a
subarea,

Portions of two or more urban watersheds (Figure 1d).
Each individual portion of a watershed would be de-
fined as a subarea.

Two or more homogenous portions of an urban watershed
(Figure le). The study area would be divided into
individual homogeneous sections with unique charac-
teristics and each individual section would be de-
fined as a subarea, This approach should be used
when the characteristics of one portion of study
area dramatically differ from the characteristics

of another portion,


Appendix A These appendices supply background information and
through

other materials essential for the use of the manual.
Appendix D


CONTENTS
(Continued)

Section

Iv

D. Treatment. . 6... 2 ew ee ee

Storage and Treatment. ....
Physical Treatment .....
Biological Treatment .......
Physical-Chemical Treatment.

E. Alternate Methods of Disposal. . .

Spray Irrigation. ........
Infiltration Ponds ........

v STATE OF THE ART. . . 1. 1 7 ee eee
Characteristics of Urban Runoff...
Characteristics of Street Surface
Contaminants. .... 1. eee eee
Impact of Urban Runoff on Receiving
Waters, 2. 2 1 ee ee ee et ee
Control Measures. .......-+2-,
References. . . 1... ee ae

Appendix
A DATA ACQUISITION AND PROCESSING FOR

CONTAMINANT LOADING RATES AND MATERIAL
COMPOSITION. 2. 2 1 1 ee ee ee ee

Literature Sources, . . . oe
Data Transformation and Aigmentation,

Data Processing... ee
Conclusions Obtained in the Data
Processing. . 6 6 6 ee ee ee ee
Summary... ......6.

Page

IV-15

IV-15
IV-19
IV-22
IV-23

IV-24

IV-24

Iv-24
V-1
V-1

V-12
V-13
V-16

A-1
A-1

A-13

A-37
A-42,


Table 14. NATIONWIDE ESTIMATES OF PARTICULATE EMISSIONS, 1970

Emissions, Percent of
Source category 106tons/year total
Transportation 0.7 2.7
Motor vehicles 0.4 1.5
Gasoline 0.3 11
Diesel 0.1 0.4
Aircraft 0.1 0.4
Railroads Neg” -
Vessels 0.1 0.4
Nonhighway use of motor fuels OL 0.4
Fuel combustion in stationary sources 6.8 26.1
Coal 5.6 21.5
Fuel oil 0.4 1.5
Natural gas 0.2 0.8
Wood 0.6 2.3
Industrial process losses 13.3 51.0
Solid waste disposal 1.4 5.3
Agricultural burning 2.4 9,2
Miscellaneous 1.5 5.7
Forest fires? 1.4 5.3
Structural fires Neg -
Coal refuse burning 0.1 0.4
Total 26.1

aNagligible (less than 0,05 x 10°tons/year),

Includes prescribed burning.

Source: EPA: Nationwide Air Pollutant Emission

Trends, 1940-1970.

IV-13


Development of Pollutograph

Using the previously developed hydrograph (Figure 28), the corresponding
pollutograph and loadograph will be developed, based on a contaminant
loading of 400 1b/curb mile. The pollutograph and loadograph will be de-

veloped in a manner similar to that portrayed in Example 7.
Po = 400 x 150 x 2 = 120,000 1b.

Values of concentration and load are plotted against time, and the re-

sultant pollutograph and loadograph are shown in Figure 29.

Quantity/Quality Hydrograph

The developed hydrographs (Figure 28), pollutograph and loadograph
(Figure 29) are superimposed as shown in Figure 30 to yield the quan-
tity/quality hydrograph which represents the study area under the

specified conditions.

Ordinates which portray the concentration and load of BOD are also
included in Figure 30. These ordinates were developed by applying
the BOD composition data as a proportionality factor to the total
solids and ordinates. Since the composition of BOD within the solids
is 30,000 mg/kg or .03 kg/kg, values of BOD will be equal to .03 times

corresponding values of total solids.

From Figure 30, it can be seen that the resultant runoff will contain
less than 30 mg/f of BOD at a time approximately 30 minutes after run-
off originates. The total load of BOD removed during this time period
is about 2,700 pounds. The runoff volume which occurs from the start
of runoff to a time 30 minutes after runoff originates is equal to the
area under the hydrograph curve from time = 0 to time = 30 minutes,
The runoff volume is graphically estimated to be about 500,000 cu ft,
or 11,48 acre-feet, which represents the volume of water that the ar-
tificial lake should be capable of accommodating.

I-25


_ Cubic Feet per Second

Hydrograph

Total Solids Concentration (Milligrams per Liter)

Time

Figure 16b. A Sample Quantity/Quality Hydrograph Comprising
a Hydrograph, a Pollutograph, and a Loadograph

1-53

Total Solids Load (Pounds)



HAND SWEEPING

Hand sweeping, or dry solids collection, should utilize a standard stiff
pristled broom, sweeping toward the curb while moving laterally along
the street, After concentration in the gutter, samples should be col-

lected by whisk broom and dustpan and placed in clean paint cans,

HOSE FLUSHING

Flushing should be conducted after sweeping to remove adherent soluble
films and otherwise nonsweepable material, The downslope gutter should
be dammed with sandbags to create a collection area for flushing water,
A small vacuum collector can be constructed using 5-gal paint cans and
connected to an industrial wet/dry vacuum cleaner, The test area is
first slightly wetted to facilitate removal of soluble materials,
Flushing should be commenced at the road crown, using a garden hose and
spray nozzle connected to fire hydrants, All water is collected by the
vacuum box and measured, The samples then are mixed by vigorous stirring
and split to a 1-gal volume, If pesticide analysis is to be conducted,
an additional sample should be taken in quart size glass containers,

Plastic gallon bottles may be used for all other samples.

Collecting rainfall runoff samples will give a definite indication of
the concentration of contaminants in the runoff, but collecting repre-
sentative samples can be difficult. Relating these runoff concentrations
to other instances (differing rainfall intensity patterns, etc.} can be
nearly impossible. In some cases, this procedure may be preferred, and

the following general instructions may be helpful.

DATA COLLECTION

Land use patterns within the watershed must be clearly defined. Per-

centages of vacant land and special sources must be identified and


The equivalent days of accumulation (EDA) factor is neces-
sary to account for residual amounts of pollutants left on
the street after the last sweeping. This residual is con-
sidered to accumulate since the last rain, heavy enough to

have removed a substantial fraction (90%) of the pollutants.

The following duration and intensities are considered heavy

enough to remove 90% of road surface particulates:

e 0.1 inch/hour for 300 minutes (5 hours)

e 0.33 inch/hour for 90 minutes (1-1/2 hours)
e 0,5 inch/hour for 60 minutes (1 hour)

e 1,0 inch/hour for 30 minutes (1/2 hour)

Each of these storms results in a total rainfall of 0.5 inch.
Therefore, the last substantial rainfall may be considered as
one resulting in 0.5 inch of rain falling within a period of one
to 5 hours. This relationship ignores the function of kinetic
energy loosening street surface particulates. Therefore, de-
viations from the modej are more substantial at lower rainfall
intensities. At higher rainfall intensities, agreement with
the model is much better,

The EDA is determined using the following relationship:

@y - Dg) (1 - Ey) + Dy

where

EDA = equivalent days of accumulation
= days since last substantial rainfall
= days since last swept (mechanically cleaned)

= effectiveness of sweeping procedure.

I-8


E, ALTERNATE METHODS OF DISPOSAL

1. Spray Irrigation

The beneficial use of stormwater runoff as irrigation water deserves

consideration. Nutrients and organic material contained in stormwater
runoff are capable of stimulating plant growth. However, the signifi-
cant concentrations of heavy metals found in stormwater runoff may im-

pair its use as irrigation water.

In certain areas, legal restrictions are placed on the use of sewage
treatment effluent as irrigation water for crops intended for direct
human consumption, Although these restrictions may also apply to a

similar use of stormwater runoff, they do not apply to crops intended

for animal consumption,

2, Infiltration Ponds

Stormwater runoff may be discharged into infiltration ponds for the pur-
pose of groundwater recharge. A degree of treatment can be imparted

to stormwater runoff which is allowed to percolate through soil. Soil
particles are capable of filtering out residue and partially treating

stormwater runoff before it reaches the groundwater table,

Iy-24


Table 1. CHARACTERISTICS OF STORMWATER RUNOFF

Suspended
BOD Total solids Solids Coliform Chlorides cOoD
city (g/t) (mg/t) (mg/t) _ (auimber/t) _(mg/t)__(me/4)
1. East Bay Sanitary
District; Oakland, California
Minimum 3 726 16 4 300
Maximum 7,700 4,400 70,000 10,260
Average 87 1,401 613 11,800 5,100
2. Cincinnati, Ohio
Maximum Seasonal Means 12 260 110
Average 17 227 111
3. Los Angeles County
Average 1962-63 161 2,909 199
4, Washington, D.C.
Catch-basin samples during storm
Minimum 6 26 11
Maximum 625 36 ,250 160
Average 126 2,100 42
5. Seattle, Washington 10 16 ,100
6. Oxney, England 1007 2,045
7. Moscow, U.S.S.R. 186-285 1,000-3,500°
8. Leningrad, U.S.S.R. 36 14,541
9. Stockholm, Sweden 17-80 30-8 ,000 40-200 ,000 18-3 ,100
10. Pretoria, South Africa
Residential 30 240 ,000 29
Business 34 230 ,000 28
b
1l. Detroit, Michigan 96~234 310-914 102-213 930 ,000°
Maximum
b,
Mean

Source: Water Pollution Aspects of Urban Runoff, APWA



ec. Swirl Concentrator

Other recent developments in physical treatment processes include a
swirl flow regulator/solids separator with no moving parts. This low
cost method of solids removal has been thoroughly tested, and proto-

type demonstration units are being constructed,

3. Biological Treatment

Although biological treatment has been a popular and successful method
of treating domestic and industrial waste water, its application to
the treatment of stormwater runoff has the following serious drawbacks:
(1) the biomass used in the treatment process must be kept alive
during nonflow periods or developed for each runoff event; and (2)
once developed, the biomass is highly susceptible to washout by hy~
draulic surges or overload unless flow equalization is maintained,

However, recent developments in biological treatment may have applica-
tions to stormwater runoff treatment. Such biological treatment pro-
cesses include: (1) the contact stabilization of activated sludge; (2)
high rate trickling filtration; (3) bioadsorption using rotating bio-
logical contactors; and (4) oxidated lagoons of various types. The
first three methods must be operated conjunctionally with dry weather
flow plants to supply the biomass, Also with the exception of lagoons,
some form of pre~unit flow equalization is necessary to prevent the

washout of the biomass,

Nearly 92 percent of the suspended solids and 83 percent of the organic
matter have been removed from combined sewer flows using the contact
stabilization method. Construction costs, excluding land, of the tested
project were $1,785/f/sec ($78,300/mgd) of capacity.

Iv~22


rrr c sm > ak ty ar s Cc A mS RS M OAD BOS COD POL TOS NOS. MERCH @DORCPECPHOC
quscen 4 3 20 10000 2 200000 520 2730

Tusces 4 2 20 19000 2 312000 450 340

TUSCEN 4 3 30 14000 1 301000 170 1020,

TUSCEN 4 1 30 14000 i 147000230 350

TUSCON 33 49 42000 ‘ 201000 240 430

TUSCON 4 3 40 42000 ‘ 228000 760 730

SAN JOSE T 8 4 20 fowoo tg ra 2 79 17000 38000 770 3600, 2300 365 30% 71 24000 2700

PHOENIX 1 & 1 20 it4oo ti te 6 2 92 10000 6000 340 450 2300 742 211 120 21000 1500

San ose tt 4 2 20 10900 4 1 $9 2 860 8900 68000 750 a5 3800 a3 45 3 5000 3400

PHOENIX. * 2 20 iik00 1 11000 58000 3 130 00 O67 41 67 15000

Savage TS 4 seep ta t 2 2 000 335 des 88 27000 e400

SAN JOSE T 8 4 22 12050 1 2 1 3 2 88 365 385 96 23000 2000,

SAN JOSE T 8 4 23 300 1 3 1 ie 2 2 415 298 33. 21000 2100

SAN JOSE T 8 4 31 3600 1 2 4 3 2 2 216 320 110 16000 3500,

SAN JOSE I 4 4 32 13000 1 1 4 18 2 2% 5:0 325 89 44000 7600,

SAN JOSE T 4 4 40 7250 1 2 § 3 2 131 368 309 87 24000 2

AN JOSE I & 4 51 7200 1 4 4 1B 2 6 22 288 67 26000 3500

PHOENIX T 9 § 1 aL 2700 1 2 t #082 077 459 203 150 23000 1200

PHOENIX T= 4 1 32 11100 t 2 1 $2 1 2 238 $15 159 39 17000 3700

PHOENIX 1 = 4 3 23 40300 1 9 1 wo7 2 18 8:8 218 tho 21000 970

HOENTX Tk Bg 41000 $2 1 ie 32 38 S10 238 83 23000 3600

PHOENIX T = 4 435 11900 1 2 4 we 12 2 66 190 69 15000 3200

PHOENIX Tg $38 45000 1% 4 113 2 53 2.0 468 25 15000 1600

PHOENIX T = & 3 40 12300 1 4 4 i028 $i» 208 100 20000 2500

PHOENIX T = 8 1 St 17200 1 0 4 i2 8 2 130 1.7 286 38 24000 1200

AN JOSE TE 2 at gyoo 1 tt 59 201 60 295 130 48000 5700

SAN JOSE IT 4 2 22 42050 1°92 1 53 2 8 2:0 36 11000 600

SAN JOSE IT 4 2 23, 300 1 3 i 59 2 S64 245 53 26000 3900

SAN Jose IT 8 231 23600 1 2 4 33 3 2 49 310 8% 30000 5400

SAN JOSE 11 4 2 32 43000 3 4 4 59 2 03 3:1 430 96 23000 9:

SAN JOSE IT § 2 40 7250 1 2 4 53 2 204 317 306 71 17000 2700

aN JOSE IE 4 2 St y200 1 4 8 59 28 ‘lo 194 92 22000 1500

PHOENIX 11 § 2 21 2700 1 3 4 60 2 8 4:1 185 99 21000 340

PHOENIX Ii § 2 2B 34300 30 a 60 2 18 063 168 7% 20000 2000

PHEENIX It 2 23 40300 1 2 4 60 2 6 » $11 52 i4000

PHOENIX It 4 2 28 {1000 4 2 1 60 2 8 ova 193 46 25000 2900

PHOENIX 11 8 2 33 31900 1 2 8 60 2 4

PHOENIX IT 4 2 32 4soo0 i 1 4 60 2 3 Ss 71 99 $000 0

ENIX 1] 4 2 12300 1 3 4 40 2 3 et 188 120 24000 2400

pase HE 3 2 a? tee 1 ft 2 ara Ho °32 2609 750

Table A-13, CLIMATE 4 - SOUTHWEST

corr © Sim AA IF at S Cc A MS RS M LOAD BODS cod POS “TPOA WO). MOR cS]. gk OL. Pom
SEATTLE 5 3 20 44700 4 12 1 000 38000 1100 59 2000 +1 243 89 29000 2100 460 32 11 490 7o7ES Qe4ED
SEATTLE 53 21 e700 1 3G 42 1 Os 233 89 27000 1700 430 13 460
SEATTLE 53 2 6900 i 4 3 12 i 34 239 100 37000 3000 430 40 66
SEATTLE 5 3 2 3200 2 4 i 12 1 2 453° 250 67 23000 2500 460 9 46
SEATTLE 5 3 25 32300 1 2 3 ie 1 4 1+6 25¢ 48 59000 2600 $40 39 10
SEATICE § 3 31 46000 $ 2 & ae 1 16 263 266 210 32000 3300 439 39 18 $00
SEATTLE 8 3 32 26500 1 2 4 42 1 48 165 247 63 42000 4700 440 40 0390
SEATTLE 5 3 40 40000 2 2 8 42 159 Ish 238 140 27000 1100 490 20 18 480

Table A-14, CLIMATE 5 - NORTHWEST


et-I

Table 4. MEAN CONCENTRATIONS OF MERCURY AND CHLORINATED
HYDROCARBONS IN STREET DIRT FROM NINE U.S, CITIES

Concentrations in micrograms per kilogram of dry solid

Methoxy- Methyl
Hg Endrin Dieldrin PCB chlor DDT Lindane Parathion DDD
Mean 83 0.2 28 770 500 76 2.9 2 82
Standard
deviation 111 - 28 770 1,050 118 7.1 - 78



Table A-2,

CODES FOR INDEPENDENT VARIABLES

Item Parameter Subcategory Numerical Code
2 Climate Northeastern 1
(see Figure A-1 Southeastern 2
and Table A-3) Midwestern 3
Southwestern 4
Northwestern 5
3 Season Annual )
Winter 1
Spring 2
Summer 3
Autumn 4
4 Land use Open land 10
General residential 20
Low income/old/single 21
Low income/old/multi 22
Median income/new/
single 23
Median income/old/
single 24
Median income/old/
multi 25
General commercial 30
Central Business 31
Shopping center 32
Light industry 40
Medium industry 51
Heavy industry 52
9 Types of street Asphalt 1
surface Concrete 2
10 Condition of the Excellent 0
street Good 1
Fair 2
Poor 3
11 Area beyond side- Lawns or grass 1
walk Trees 2
Landscaped buildings 3
Pavement or bare 4
15 Method of cleaning Swept and flushed 1
Swept only 2
No cleaning 3

A-4


be-V

on
CINCINNATI

GRAND RAPIDS
GRAND RAPIDS:

SEATILE

9
3
8
3
3

7

a

2018

Table A-17,

ave
655

ons
268

75000

2620
2139

050

2510

5390
$980
aso
3280
2630

595

730

3620
63

9250

8800
$50

on?

cr

120
80
100
48
110

AVERAGE DAILY TRAFFIC - 5000 to 15,000

3100

a7

rom
2ete6

root
6268



€T-II

Total Solids (Milligrams per Liter)

4000 4

3000 +

2000 +

1000+

40,000
Loadograph
——_—— — —— —_— H30 000
20,000
Pollutograph

P-10,000

ri) T y tT T T

40 60 80 100 120

Time (minutes)

Figure 23, Pollutograph and Loadograph Developed in Example 7

Total Solids Load (Pounds)


are required to better evaluate the efficiency of organic removal.
The average capital cost of these screening processes, based on a de~

sign flow rate of 17 f/sec/sq m (25 gpm/sq ft) is approximately $297/
Q/sec ($13, 000/mgd).

A study has been begun recently to compare the effectiveness of three
screening devices (ultrafine screen, rotary fine screen, and stable

screen) operating on combined sewage overflows.

b. High and Ultrahigh Rate Filtration

Effective treatment of combined sewer overflow containing an average

of 250 mg/f suspended solids and 67 mg/f BOD was obtained in a treat-
ment plant in Cleveland, Ohio, by adding a polyelectrolyte and then
filtering the influent through a deep bed, dual media filter at a

rate of 24 gpm/sq ft. This method resulted in a 93 percent reduction
of suspended solids and a 61 percent reduction in the BOD, Total

annual treatment costs (capital and operating) were estimated at $90,000

for a 25-mgd plant and $390,000 for a 200-mgd plant.

Successful results on a bench scale, have also been obtained from ultra-
high rate filtration of stormwater runoff. Filtration rates up to 30
f/sec/sq m (45 gpm/sq ft) through a dual media filter, following pre-
treatment through an ultrafine screen, have resulted in suspended

solids removal of 38 to 73 percent and organic removals of 8 to 36 per-

cent.

The advantages of these treatment processes are (1) high removal effi-
ciencies, (2) automated operation, and (3) limited space requirements

(as opposed to flotation and sedimentation).

Iv-21


6. Convert the load to load/acre as follows, using the
curb ‘mile density factor in Table 2:

150 1b/curb mi x 0.54 curb mi/acre = 81.0 1b/acre
EXAMPLE 3

An urban watershed consists of 200 acres of land with essentially all
impervious surface and a relatively flat slope.

a. What is the rate of runoff resulting from a storm with
an intensity of 0.5 in./hr which lasts for 1 hour?

= kP

0.80 from Table 8

(0.80) (0.5 in./hr) = 0.4 in./hr

Dw
il)

b. What rainfall intensity will produce a runoff rate of
0.5 in./hr from the same watershed?

R = kP
R
Prk
— (0.5 in./hr) _
P= — 73807 —CO 0.63 in./hr

EXAMPLE 4

An urban watershed consists of 400 acres of land with a moderate slope.
The watershed comprises 200 acres of impervious surface and 200 acres
of pervious surface with lawns and heavy soils. What rate of runoff

will result from a storm with an intensity of 0.33 in./hr which lasts
for 45 minutes? (Only impervious area is considered as explained

earlier.)

k = 0.85 from Table 8,
‘imp
R = kP
R = (0,85) (0.33 in./hr) = 0,28 in./hr

TI-6


"Stormwater disinfection at New Orleans," Edgar H, Pavia and Crawford J.
Powell, JOURNAL WPCF, 41(4):591-606, 4/69,

"Storm water for fun and profit," John R, Sheaffer, WATER SPECTRUM, 2(3):
29-34, Fall 1970,

STORM WATER MANAGEMENT MODEL, Vols, I-IV, Metcalf and Eddy, Inc, for EPA,
7/71-10/71.

STORM WATER POLLUTION FROM URBAN LAND ACTIVITY, AVCO Economic Systems Corp.
for FWQA, 11034 FKL, 7/70,

STORM WATER POLLUTION, NEW ORLEANS, LOUISIANA; Final report on the sources
of storm water pollution by sewage from sanitary sewers, Sewerage and
Water Board of New Orleans, 7/70,

STORM WATER POLLUTION, NEW ORLEANS, LOUISIANA; Supplementary report covering
repair work,

STORM WATER PROBLEMS AND CONTROL IN SANITARY SEWERS, OAKLAND AND BERKELEY,
CALIFORNIA, Metcalf and Eddy, Inc. for Water Quality Office, EPA, 11024
EQ, 3/71.

STORM WATER RUNOFF FROM AN URBAN HIGHWAY DRAINAGE SYSTEM, K. Morrison,
J.B. Kim, F.W. Ellerman, J.I. Chang, and H.H. Liu, D.C. Dept. of Highways
and Traffic, Final Research Rept., 8/25/71.

“Storm Water to cool?" WATER AND WASTES ENGINEERING, 8(9):12, 9/71.

STREAM POLLUTION AND ABATEMENT FROM COMBINED SEWER OVERFLOWS; A study of
stream pollution from combined sewer overflows and feasibility of
alternate plans for pollution abatement in Bucyrus, Ohio, Burgess &
Niple, Ltd. for FWPCA, 11/69.

STUDIES OF STORM AND COMBINED SEWER POLLUTION OF THE SOUTH RIVER DRAINAGE
BASIN, CITY OF ATLANTA, GEORGIA, Black, Crow and Eidsness, Inc, for FWPCA,
draft rept.

A STUDY OF METHODS USED IN MEASUREMENT AND ANALYSIS OF SEDIMENT LOADS IN
STREAMS, Federal Inter-Agency Sedimentation Project, rev. 4/69,

A SUMMARY OF METHODS FOR THE COLLECTION AND ANALYSIS OF BASIC HYDROLOGIC
DATA FOR ARID REGIONS, U.S.G.S. Water Resources Div. Open File Rept.

"Surface runoff determination from rainfall without using coefficients,”
W.W. Horner and S,W, Jens, ASCE TRANSACTIONS, Paper No, 2153,

SURFACE STORM WATER RUNOFF AND DRAINAGE STUDY FOR ESSEX COUNTY, NEW JERSEY,
Essex Co, Dept. of Planning, Economic Development, and Conservation,
12/69.


Te-V

Table A-23 (continued)

Ibs/curd ni/day Concentrations in Micrograms per Gram of Dry Solids wo. /ereme
category Loading cop 0P0, TPO, Wo. mi, Oren cd co oe ve Pb Mo Mo OSE zn reolt” Fools”
w 1 150 23,000 150,000 2,470 «212,11, 600 - M70 nr 107 22,400 2,000 414 491880 - -
° ° ns 14,900 91,000 362 - ne) ee -
= ® - $,300- 49,000- 1, 600— - - - Me 25+ M1000- > 210- oe > 110- = -

bat 950 43,900 298,000 3,000 430300 48,000 7,600 830 78 880
> wy ® 65 ° 9 a ,ooe ’ 3 00 38 o © S38 se -
o
a
Hr. Ff 38 72,000 383,000 3,520 5,150 7,600 3,620 «6,680 3.57797 22,800 1,280 M2 HAS 282 - -
o « v 31,200 163,900 1,730 = 920 1,00 4940200300 aha -
= ® 16- 19,000 114,000- 1,600- 4,850- 1,810 1,880- —1,900- 0.6 2h GBD 290-100 -
fe ° 175}000 611,000 6,670 $,440 4,400. $1390 12,800 9.3 «305.150 $3,000 2,500 «520, 500
° Ls 16 as aa 3 2 7 6 12010 n ue 10 10 10 10 aw 10 - -
x 156 19,900 140,000 1,280 2,930 «802,640 «2,950 34 «211.10 22,020 18051835 2k 702,386 ALPES
a= ° 220 19,800 153,000 2,480 1,750 977 «1,820 2,850 26390 589,980 1,290 © 130337705. 2.9ES
a5 ® a 18,000- Meme 4s-595- 40-0 = 92,2006 47-160 S7- 1.06 6.78I~
z= 950 611,000 6,670 5,460 3,600 5,390 10,500 9.2585 300 39,000 3,700 ©3040 788A]. NLAEY «1.286,
x us 8 6 7 sy “wom oo ” Cn
4+ Blanks indicate thet no
‘= Colitorm counts are expressed in computer notation, 4. 6 = 108,



The purpose of this manual is to provide state and local water quality
Management planners with a means of identifying and characterizing urban
runoff as a non-point source of water pollution without extensive data
generation, It is not intended to serve as a design manual nor as an ab-
solute source of information on the subject. Rather, it is intended to
give a general, first-glance assessment of the water quality aspects of

urban runoff within a specified urban area.

The analytical procedures described in this manual are identified accord-
ing to three levels of assessment: Levels I, II, and III. The level of
assessment selected by the user will vary according to the required accu-
racy and the effort to be expended. As one progresses from Level I to
Level III, the analytical procedures will require increasingly more effort

but will yield correspondingly higher degrees of accuracy.

Consistent with the idea of a "manual," numerous example problems have
been provided to illustrate analytical methods and procedures, In addi-
tion, an extensive annotated bibliography and an information matrix have
been included to provide additional information on specific aspects of

urban runoff,

A very sophisticated assessment of storm water runoff can be accomplished
by utilizing the U.S. Environmental Protection Agency's Storm Water Manage-
ment Model. This model is a computer system capable of simulating the
quantity and quality of urban storm water runoff. Ideally, the combina-
tion of this manual and the Storm Water Management Model can provide wa-
ter quality management planners with an entire spectrum of analytical
tools, ranging from simple desk calculations to sophisticated computer

techniques.

The initial construction of the manual was intended to provide an assess-—
ment of total runoff flowing from an urbanized area. The model selected

for runoff quantity determination was developed for this purpose. However,


@I-Il

POLLUTOGRAPH AND LOADOGRAPH WORKSHEET

STREET SURFACE RUNOFF

— = P TOTAL TOTAL SOLIDS
At VOLUME ave ° AP SAP VOLUME CONCENTRATION
(min) (cu ft) (in. /hr) (1b) (1b) (1b) (cu ft) (mg/ 2)
O- 12.5 16,900 0,200 30, 000 5,750 5,750 26,500 3,476
12.5- 25 72,000 0.850 24,250 19,750 25,500 112,500 2,812
25 - 37.5 122,500 1.446 4,500 4,500 30,000 192,000 375
37.5- 50 102,000 1.204 ti) Co) 30,000 160,000 0
50 - 62.5 62,000 0.732 Co) 0 30,000 97,000 0
62.5- 75 42,000 0.500 Co) to) 30, 000 66,000 to)
75 - 87.5 30,000 0.354 0 to) 30,000 47,500 0
87,5-100 21,700 0,256 to) to) 30,000 34,000 (i)
100 -112.5 14,600 0.172 te) 0 30, 000 23,000 0
112,.5-125 10, 200 0.120 0 to) 30,000 16, 000 0
125 -137.5 6,100 0.072 to) ) 30,000 9,500 ti)
137.5-150 2,900 0,034 te) to) 30,000 4,500 0

Following equations have been used in preparing the above table.

Volume

"ave (in. /hr)

AP

Conc, (mg/g) =

a,

ve x Onin x 60

Volume (cu'ft)

Oty in * Aaeres * (60-5)
(At)

(4.6 Tove P)) 5 oe)

min

AP X 16,019

Runoff Volume from Total Imp. Area


S@-v

ary

cHICAGS
cHICAGS
CENT +ByS+
‘SHOP «CENTER
PHOENIX 1
PHOENIX 1
MILWAUKEE
MILWAUKEE
BAL TIMBRE

LUO NNNUNWANEHOOWW ao

3
naw emnonoonnor

Table

a
»

pepe ereuseerrene p

A-18,

SM von
12 326 28800
22 (96 32100

296 30000
tee 21000

13 33
8 130
ey 770
7 30
4 i
4 16

renee eee oO

27

RODS COD GPO TOM HOS

cack >

1600 645
1600 367
20

17

203

302

37

ray

ry

os

ee

166

rr

O03

263

15

AVERAGE DAILY TRAFFIC - GREATER THAN

aia w 7B

15,000

‘TeoLT

eRe
30965
ete
20086

Be0E8



subarea 1 at time t - ats and the flow and quality of subarea 2 at
time t - ty into the equations.

@ time t

Fp, t=15

%, t=15

% ta15
Lp ta15

For example:

15
Fitce.s + Fa,te1o = 160+ 130 = 290 cfs
F.
1 toes) “Gi te6.5? * “es te10? &, e210?
i te6.5? + 2, 210?

(160) (2800) + (130) (1300)

(60) + (130) 2230 me/t
Ly tc6.5 + Ya taro 7 250+ 88 = 338 1b

In a similar manner, other values for the composite flow, pollutant concen-

tration, and pollutant load can be ascertained:

t

5
15
25,
35
45
55
65
15

Fit-s.s ,t-8.5 Tajt-s.5 "e,t-5 %,t-5 "2,t-5 "vt t+ Tot

to) () ° 0 1,500 0 0 0 0

160 2,800 250 130 1,300 88 290 2,130 338
300 1,700 535 140 750 155 440 1,400 690
200 750 665 90 280 185 290 600 825
120 440 700 65 200 = 187 185 360 887

70 400 720 30 200 ~=189 100 340 909

25 400 730 10 200 = 190 35 340 920

10 400 735 0 200 «191 10 400 926

t ti t ield t -
The values of Pot % and Ly it are plotted agains ime to yie he com:

posite quantity/quality hydrograph representing the entire study area as

shown in Figure 26,

II-17


10.

ll.

12,

INFORMATION MATRIX REPORT CODE REFERENCES

"Application of an electronic analog computer to the evaluation of the
effects of urbanization on the runoff characteristics of small watersheds, "
V.V. Dhruva Narayana and J. Paul Riley, THE USE OF ANALOG AND DIGITAL
COMPUTERS IN HYDROLOGY, Proceedings of the Tucson Symposium, 1:38-48,

“Assessing the quality of urban drainage," Warren Viessman, Jr., PUBLIC
WORKS, 10/69.

"The bacteriological aspects of stormwater pollution," E.E. Geldreich,
L.C. Best, B.A. Kenner, and D.J. Van Donsel, JOURNAL WPCF, 40(11,1):
1861-1872, 11/68,

"Bacteriological comparison between combined and separate sewer discharges
in southeastern Michigan,” R.J, Burm and R.D. Vaughan, JOURNAL WPCF, 38(3):
400-409, 3/66.

THE BENEFICIAL USE OF STORM WATER, C.W. Mallory, Office of Research and
Monitoring, EPA, R2-73-139, 1/73,

"Calculation of water pollution by surface runoff," N.A. Pravoshinsky and
P.D, Gatillo, WATER RESEARCH, 2(1):24-26, 1/68,

CHARACTER AND SIGNIFICANCE OF HIGHWAY RUNOFF WATERS, A PRELIMINARY
APPRAISAL, Robert O. Sylvester and Foppe B. DeWalle, Washington State
Highway Commission, 12/29/72.

"Characterization, treatment, and disposal of urban stormwater," S.R.
Weibel, R.B. Weidner, A.G. Christianson, and R.J, Anderson, PROCEEDINGS,
3RD INTERNATIONAL CONFERENCE ON WATER POLLUTION RESEARCH, Munich, 1:1966,

“Chemical and physical comparison of combined and separate sewer discharges,"
R.J. Burm, D.F, Krawezyk, and G,L, Harlow, JOURNAL WPCF, 40(1):112-126, 1/68.

"Deep tunnel storage may solve city storm water problem,” ENVIRONMENTAL
SCIENCE AND TECHNOLOGY, 3(3):209-211, 3/69.

"Development of a simulation model for stormwater management," J,A. Lager,
R.P, Shubinski, and L.W, Russell, JOURNAL WPCF, 43(12):2424-2435, 12/71.

"Dustfall as a source of water quality impairment," R.E. Johnson, A.T,

Rossano, Jr., and R,O. Sylvester, JOURNAL SANITARY ENGINEERING DIVISION,
ASCE, SA1:245, 2/66,

C-13


i

i.

k,

1.

Organic Nitrogen Concentrations Are Lowest in:

1.

*2,

Heavy industry areas

The southeast; and unexpected finding since the southeast con-

tains the most lush vegetation
Areas with moderate traffic (500-5000 ADT)
Areas without landscaping

Asphalt surfaces

Cadmium Concentrations Are Relatively Uniform in All Categories

Chromium Concentrations Are Lowest in:

1.

*2,

Residential areas

The northeast; unexpected since the major source of chromium
on streets was thought to be, chromate salts added to deicing

salt as a metal preservative
No significant differences with traffic density
No significant difference with landscaping

On concrete surfaces

Copper Concentrations Are Lowest in:

Not significantly different between street surface types

1. Residential areas

2. The southwest

3. Areas with light traffic «500 ADT)

4, Areas with grass landscaping

5.

Iron Concentrations Are Lowest in:

1, Not significantly different with land use types
*2, Lowest in the northeast (highest in northwest)
3.

Not significantly different with traffic density

A-39


Table A-23 (continued)

oe-V

Ue/eurd mt /dey Concentrations in Microgrens par Gram of Dry Solids Ko.ferem
’ Loading ‘cop oro, TRO, or ee wo ML oe tutes” cot s®
0 280 21,600 133,000 1,500 5,440 8,335 = 5,470 208k 3 26282 1,386 69
° ery - - - - - - 200% Oo” 100-23 1S 100 2.086 1.685
a ae 6,220- 45,600- 3 =e = me ae 20" 7-8 9.082
950 39,600 252, 2,700 16,000 $4288 6200-7533 420s 4.3ES
x 2 ‘ ‘ 3 1 20 = 8 , 9 os 68 8 so8 a
soo-sk X Mo 9,300 m1 2A = ASS 29196107 18,900 1,060 ws ah Nasa
« ass 8,520 950 - wm 616 E S00 92S KBB 198 SKE
R 20- 1,720- 18,300- 202 = Ca 890 Late 136714000 6S NLL SED
600 25,300 277,000 2,800, as 2,200 61 320-—170-—«23,000 «3,500 70035, 760.« «9.686 1386
» % 6 16 1s 1 nos 72 non moo om om oo oD 6
sxeask ¥ 16 27,400 163,000 1,340 8362640 2,900 3.8 S107 Cc a ee}
° an 26,000 165,000 1,250 791,820 2430588 35106?
R 2,900- 18,000- 30+ ee eh 160-2
16 aolion 52 5,050 1600 5,390 9,250 9:3 430300 1,100 14063780 3.487 9.88
" oN 8 “a yoo ws 6 6 a |
vise X a 5,720 26,980 S14 = Sk = 16003, 20302 22,900 2,230 387 1,485
° 208 - - - - - os = 21 93 68 13,600 1,330 305 2.483
R + wee Ce er oer ee eee 1,262-
326 1,000 00 6.0 94550 53,000 5,00 500, Saas
x v ‘ - se 2 6 we we sas u
1k 196 32,400 154,000 1,720 3,S00 1,010 3,620 «3,900 9796 1,080 1,370 606-27 th KBE.
° 25 37,900 172,000 14490 2,860 © 2,320 1,803,240 398500, 9801572520681.
R So 2,200- 8,300- 100-212-3718 BD 63-3 8100-25-80 38
950 36,700 526,000 5,790 5,440 3,600 5,390 11,900 365190 $3,000 9,900 1,100 9693 BBO 8.468.388
® 35 2 a 2 a as 6 % a2 9 Pe a
2% ” 23,000 142,300 1,240 a - - - - - - oe oe = 1187 ses
2 ° x 21,300 108,000 - - rr rr are)
€ 2 19. 2,900- 26,500 - - : - - - - - ee = 3.985 7.083
> 36 6713003125000 : Seer 1.386
w - -
w x n 10 2 - - - - - - - - no
= 2 ¥ 2 9,990 86,900 a24 - nm = 2,600 sh 26220 34,500 2,950 4909322 SH2 SEE 3 SES.
= ° 56 11,600 96,900 2,370 - mm - - + - - - - - se = 3.086 148s
< 2 - 2,030- 24,6002 2 =SB= 210-48 19,000 1,700- 290+ T= BAND. DES~ 7.083
13 243300. 277/000 3,200 6 264 210 $9,000 3,000» $00. AS33660 1.086
" a0 ? ? 7 - soe ‘ ‘ ‘ ‘ oo aos ‘
oo am 33,700 70,000 78724510 6k 62 3.6 228 622,000 2,370 Bak
. as 10,200 72,100 390 - me 21 879,320,720 Sh waa
. R - 2,180- 21,000- 30-2,130- 726 595+ oe ae Coes ee a Oo
800 38J000 226,000 1,800 24770790730 88 430300 42,000 5,700 007720

” rr) a a3 y ‘ 16 3 “ 3s 3 36 ” 3 OS Par)



REFERENCES

Field, R., et al., "Water Pollution and Associated Effects of Street
Salting," National Environmental Research Center, EPA (May 1973).

"Environmental Impact of Highway Deicing,” 11040 GKK 06/71 Storm and
Combined Sewer Technology Branch, Edison Water Quality Research
Laboratory, EPA (June 1971).

Hanes, R. E., et al., "Effects of Deicing Salts on Water Quality and
Biota -~ Literature Review and Recommended Research," National
Cooperative Highway Research Program Report 91, Virginia Polytechnic
Institute and Highway Research Board (1970).

IIiI-4


Total Solids Concentration {Milligrams per Liter)

Total Solids Load(Pounds)

Time
Figure 15a. A Sample Pollutograph

Time

Figure 15b,. A Sample Loadograph

I-49


6.0 QUANTITY/QUALITY HYDROGRAPHS

The procedures thus far presented enable the user to develop a quantity/
quality hydrograph for an entire study area or for individual subareas.
The ordinates of a quantity/quality hydrograph represent values of run-
off flow, total solids concentration, and accumulative solids load at
the inlet of the study area (i.e., the downstream location where the

main drainage channel intersects the perimeter,of the study area).
At this point, several more analytical tools are required for one to
complete an assessment of urban runoff. These analytical tools will

be provided within the following sections.

6.1 Method of Routing Quantity/Quality Hydrographs

No analytical techniques have thus far been presented to enable the user
(1) to combine the quantity/quality hydrographs of two or more subareas
into a single composite quantity/quality hydrograph representing an en-
tire study area and (2) to modify the time base of the study area quan-
tity/quality hydrograph such that it represents the quantity and quali-
ty characteristics of runoff at an outfall or point of discharge into a
receiving water (as opposed to the inlet of the study area). The fol-
lowing discussion describes a “routing’ technique which enables the user

to accomplish both of these tasks.

Consider a hypothetical study area (Figure 17) consisting of two identi-
cal subareas. The respective inlets are identified as inlets 1 and 2
while D represents the point of discharge. The flow and quality charac-
teristics of runoff entering inlets 1 and 2 at time t can be expressed

as:


ce. COD Concentrations Are Lowest in:

1.

Residential and heavy industry, whereas it is highest in
commercial areas; the latter may be due to oil from many

parked cars on the street

Not significantly different climatologically
Areas with moderate traffic (500-5000 ADT)
Areas with landscaped buildings

Not significantly different between street surface types

d. Ortho Phosphate Concentrations Are Lowest in:

*1.

5.

Residential areas; an unexpected finding considering the wide-

spread use of fertilizer on lawns

The southwest (highest in southeast), probably reflecting the

difference in vegetation or fertilizing practices
Areas with moderate traffic (500-5000 ADT)

Areas with no landscaping, probably because no fertilizer is

used

On asphalt surfaces

e, No Conclusions Can Be Obtained From the Total Phosphate Data

f, Nitrate Concentrations Are Lowest in:

1.

Heavy industry areas

No significant differences climatologically

No significant differences between traffic densities
Areas without landscaping

No significant difference between street surface types

g. No Conclusions Can Be Obtained from the Ammonia Data

A-38


Section I

AN ASSESSMENT OF

URBAN RUNOFF QUANTITY AND QUALITY


10,

ll.

12,

REFERENCES

Shigorin, G. G., "The Problem of City Surface Run-Off Water,"
Vodosnabzhenie i Sanitarnaya Tekhnika (1956).

Akerlinch, G., "The Quality of Storm Water Flow," Nordisk Hygienish
Tidskrift, Stockholm (1950).

Palmer, C. L., "The Pollutional Effects of Storm-Water Overflows
from Combined Sewers," Sewage and Industrial Wastes, Vol. 22, No. 2
(February 1950).

Wilkinson, R., "The Quality of Rainfall Run-Off Water from a Housing
Estate," Jour. Inst. Pub, Health Eng., London.

Sylvester, R. O., An Engineering and Ecological Study for the Rehabili-
tation of Green Lake, University of Washington, Seattle, Washington
(1960).

Stander, G. J., "Topographical Pollution ~~ The Problems of the Water
and Sanitary Engineer," 40th Annual Conf. Inst. of Municipal Engineers,
Natl, Inst. for Water Research, South Africa (1961).

Weibel, S. R., R. J. Anderson, and R. L. Woodward, "Urban Land Runoff
as a Factor in Stream Pollution," Journal Water Pollution Control
Federation, Vol, 36, No, 7 (July 1964),

Bryan, E, H., Quality of Stormwater Drainage from Urban Land Areas in
North Carolina, Water Resources Research Institute of the University
of North Carolina, Report No. 37 (June 1970).

AVCO Economic Systems Corporation, Storm Water Pollution from Urban
Land Activity for the Federal Water Quality Administration, Publication
11034 FKL (July 1970),

American Public Works Association, Water Pollution Aspects of Urban
Runoff, Federal Water Pollution Control Administration, Water Pollution
Control Research Series WP-20-15 (January 1969).

Sartor, J. D., and G, B, Boyd, Water Pollution Aspects of Street Surface
Contaminants, Environmental Protection Agency, Research and Monitoring
Environmental Protection Technology Series, EPA-R2-72-081 (November 1972).

Pitt, R. E,, and G, Amy, Toxic Material Analysis of Street Surface

Contaminants, Environmental Protection Agency, Municipal Pollution Control

Branch (1973).

v-16


36, Total Coliforms (TColi) - bacterial indicators of less recent
pollution and/or the existence of defects in water treatment or
distribution (these bacteria are of nonfecal origin usually orig-

inating in soil).

37, Total Phosphorus (TPO) - shows all types of phosphorus occurring
aa Eee gt
in a water system (ortho-, poly- and organic) and is a good indi-

cator of the potential biological productivity of the water.

38, Zinc (Zn) - an essential element in human health which, when pres-
ent in excess, can impart a milky appearance and metallic taste

to water supplies, Is toxic to many organisms in large quantities.


EXAMPLE 8

A 300-acre parcel of urban land consists of 200 acres of industrial land
use and 100 acres of residential land use as shown in Figure 24. Quan-
tity/quality hydrographs which describe the two subareas are given in
Figure 25.

Using the routing technique described in Section I, combine the quan-
tity/quality characteristics of the two subareas into a composite quan-

tity/quality hydrograph representing the entire study area,

At.

1 lag time from inlet 1 to D

At. lag time from inlet 2 to D

2

From Figure 18 Nomograph:

At

L 510 sec = 8,5 min

at, 300 sec = 5.0 min

u

2

The accumulative flow and quality of runoff at time t at the point of

discharge D can be expressed by:

F = F F
D,t 1, t= at, * 2, t-At,
@, pop) © > + (F. > ¢ )
. z,teat,’ “Wh t-at, 2, t-Aty %2, tat,
t (F > + & )
4 1,t-at, 2, t-At,
= .L +L
It 1, tat, 2, tat,

The composite quantity/quality hydrograph can be plotted by substituting
values of flow and quality read from the subarea quantity/quality hydro-
graphs into the above equations, A value for the composite flow and qual-

ity at time t can be ascertained by substituting the flow and quality of
11-14


3.0 DATA REQUIREMENTS

The analytical techniques presented in this section are such that minimal
data are required. It was felt that inadequate or unavailable data should
not prevent a community from using the techniques of this section. There-
fore, most of the selected data parameters are readily available in most
communities and can be easily approximated in others when not available.
The data requirements for the analytical techniques within this section

are:

e Study area characteristics
e Contaminant loading and materials composition
e Storm event characteristics and impervious runoff rate

3.1 Study Area Characteristics

Several physical characteristics of the study area are required as data by
the analytical techniques presented in this section. They include:

e Size of study area (acres)

e Amount of interconnected impervious area within
study area (acres)

e Amount of street surface area within study area
(acres)

o Length of main drainage channel (feet)
e Average slope of main drainage channel (feet/feet)

If a study area is subdivided into two or more subareas, the physical char-
acteristics of each subarea (i.e., subarea size, amount of interconnected

impervious area within subarea, etc,) are required as data,

The amount of interconnected impervious area and street surface area can
be estimated from aerial photographs or engineering maps. The estimate
of interconnected impervious surfaces should not include rooftops which

drain directly onto lawns, or other impervious surfaces which are not

I-5


.001 4

Example: .

1,000

300 4

Figure 7,
Slope = 0,005

Reference
Line

Qa
4.04

0.5-

Nomograph

Length of Main Drainage Path = 3,000 ft

Imperviousness = 50%
Therefore 2 = 1.2
1-34


Q, Discharge in CFS

300

275
250 {>
/ (22a)
225 |—“Impervious Surface Rynoff

200 ] \
175

et Lr |

LL

| \ \ (22b)
KX Strpet Surface Runoff

LL

\
N

LU

SAK

Af

25 50

7

5 100

T, Time in Minutes

Figure 22, Unit Hydrographs Developed in Example 6

II-1

to)

125 150


all data and enter the appropriate table at the line labeled
"All Data."

b, Select a category of land use, climate, average daily traf-
fic, landscaping, or street surface material which best
applies to the area of study and move upward to the line of

data to the right of that category heading,

c. Substitute those values available in the row selected
for the corresponding values in the row entitled "All
Data." The resulting row of data may be used in all
later steps. Caution: It is not permissible to use
more than one row of substitutions at a time, i.e., to
use a BOD value for land use and COD for climate to
form a new row of loading rate and composition data,
Analysis of the data indicates that there is a relation-
ship between loadings by category but that this rela-
tionship is not valid when categories are mixed, It is
both proper and useful, however, to repeat the above
process to obtain several new rows of data to present

a range of composition and loading rates,

d. Attach the data from Table 4, if desired.

e. Convert the loading rate to load per acre of street sur-
face as described in the discussion for Level I, Carry

the composition data along for subsequent use.

e Level III. This level makes maximum use of the available loading

rate and solid composition data, Alternatively, the published available
data may be replaced by site specific data available to the user. Recom-
mended procedures for conducting site specific tests are given in Appen-

dix B,

I-17


Table A-3, CLIMATOLOGICAL CATEGORIES

Code Description

1 Precipitation is not seasonal but relatively even year
round, Winters are cold with snow; summers are moder-
ate to hot and humid, Extremes in climate summer to
winter. Precipitation is about 40 inches/year,

2 Precipitation is about 40 inches/year divided about
evenly throughout the year. Summers are hot and humid;
winters are mild and wet with little snow.

3 Precipitation is less than 30 inches/year but about
evenly divided, Summers are hot; winters are arctic
and long. Suffers from great plains or tundra type
weather with wind and violent storms.

4 Precipitation is light and seasonal with about 10-20
inches/year, falling mostly in winter. Summers are
hot and dry; winters are moderate with rain. Snow
only in higher elevations.

5 Precipitation is about 40-60 inches/year and seasonal,
falling mostly in winter. Winters are cold but not
arctic, Frequent snowfalls but precipitation largely
as rain. Summers are moderate and dry.

6 National average climate, This is a meaningless cate-
gory and was employed only to give the computer a code
to reject average climate values into,

A-6


The emissions from mobile sources are controlled by state and federal
agencies, The EPA has not proposed any particulate emission controls
for automobiles, but has for other types of vehicles (heavy duty, air-

craft, vessels, etc,).

Iv-14


Section I
AN ASSESSMENT OF URBAN RUNOFF QUANTITY AND QUALITY

1.0 GENERAL CONSIDERATIONS

This section provides a hierarchy of analytical methods to assess the
water pollution characteristics of urban runoff at several levels of
sophistication, The most accurate and definitive methods are the most
difficult to utilize while more simplistic methods are presented to al-

low the user to obtain approximate estimates.

The water pollution characteristics of urban runoff are related to both
the quantity and quality of runoff. The analytical methods presented in
this section will enable the user to assess the quality and quantity of
runoff as a function of time. Variations with respect to time are espe-
cially important if treatment, storage, or alternate methods of disposal
are under consideration, since it enables one to identify the most pol-

luted portion of the runoff.

Theoretically, the phenomenon of urban runoff can be described in a qual-
itative manner, Initially, contaminants accumulate upon urban land sur-
faces as a function of dustfall, street sweeping frequency, antecedent
rainfall characteristics, etc, When a rain event occurs, the energy of
dissipating raindrops dislodges contaminants from street surfaces, roof
tops, and other urban sources, causing some contaminant particles to be-
come suspended in solution, The soluble fraction of material goes into
solution. Subsequently, runoff transports contaminants across urban
land and into gutters and storm sewers, and eventually, runoff is dis-
charged into receiving waters from storm sewers, The pollutant con-
centration is greatest at the beginning of a rainfall event and as the

rainfall continues, subsequent runoff becomes less contaminated,


20 minutes after impervious runoff begins. Generally, it is believed that
the adaptation of Espey's equations for the development of impervious sur-
face and street surface unit hydrographs yields adequate results, in light

of the manual's intended degree of accuracy.

4.6 Modification of Unit Hydrographs to Reflect Specific Runoff Rate

As previously indicated, a unit hydrograph represents the direct run-
off resulting from 1 inch of effective rainfall (rainfall which causes
runoff), generated uniformly over an area at a uniform rate during a
period of 30 minutes. Once a unit hydrograph has been derived for an
area, the unit hydrograph can be modified to reflect a specific runoff
rate for the area under consideration, whether it be an entire study
area, the impervious area within a study area, or the street surface

area within a study area, This modification of the unit hydrograph
reduces its value as an indicator of the watershed hydrologic character-
istics but is is justified within the limits of accuracy of the procedure

as a whole.

The modification of a unit hydrograph to reflect a specific runoff rate
is a simple graphical procedure. Since a unit hydrograph represents 1
inch of runoff during an interval of 30 minutes, the implied rate of
runoff is 2 inches per hour, Accordingly, modification of the runoff
rate is accomplished by multiplying the ordinates of a unit hydrograph
by the ratio of: Specific Runoff Rate/2 inches per hour.

For example, in order to modify a unit hydrograph to reflect a runoff
rate of 1 inch per hour, multiply the ordinates of the unit hydrograph
by the ratio of 1 inch per hour/2 inches per hour = 1/2, This is shown
graphically in Figure 14.

1-45


PROPOSED COMBINED SEWER CONTROL BY ELECTRODE POTENTIAL, Merrimack College
for FWQA, 11024 DOK, 2/70.

"Protecting steep construction slopes against water erosion," N.P. Swanson,
A.R, Dedrick, and A.E. Dudeck, HIGHWAY RESEARCH RECORD, 206:46-52, 1967.

QUALITY OF RUNOFF FROM DIVERSIFIED URBAN WATERSHEDS, Vishu V, Dharmadhikari,
M.A, Thesis for U, of Arizona, Dept, of Civil Engineering and Engineering
Mechanics, 1970.

"Quality of stormwater drainage from urban land," E,H. Bryan, Water Res.
Bull. 8(3):578-588, 1972.

QUALITY OF STORMWATER DRAINAGE FROM URBAN LAND AREAS IN NORTH CAROLINA,
Edward H. Bryan, Duke University, Durham, North Carolina, for Water
Resources Research Institute, University of North Carolina, Raleigh
Report No, 37, 6/70,

"Quantity of water from rainfall,” W.A, Hardenbergh, WATER SUPPLY AND
WASTE DISPOSAL, Chapt. 2, 8-39,

"The rational method," Capt. Charles C, McCloskey, III, THE MILITARY
ENGINEER, 1-2/72,

"Real-time computer control of urban runoff," James J, Anderson, JOURNAL
HYDRAULICS DIVISION, ASCE, HY1:153, 1/70.

REPORT ON PROBLEMS OF COMBINED SEWER FACILITIES AND OVERFLOWS, 1967, FWPCA,
12/1/67,

"Roadside sediment production and control," E.G. Discker and E.C, Richardson,
TRANSACTIONS OF THE ASAE, 4:63-68, 1961.

ROTARY VIBRATORY FINE SCREENING OF COMBINED SEWER OVERFLOWS, Cornell, Howland,
Hayes and Merryfield for FWQA, 11023 FDD, 3/70.

"Runoff - a potential resource,” Eric F, Mische and Vishnu V. Dharmadhikari,
WATER AND WASTES ENGINEERING, 8(2):28-31, 2/71.

"Runoff forecasting by variable transformation," Mikio Hino, JOURNAL
HYDRAULICS DIVISION, ASCE, HY4:871, 4/70.

"Runoff from combined rural and urban areas," L.H, Watkins, RIVER ENGINEERING
AND WATER CONSERVATION WORKS, Chapt. 7:111-121, 1966,

"Runoff volumes from small urban watersheds," Clayton R, Miller and Warren
Viessman, Jr., WATER RESOURCES RESEARCH, 8(2):429, 4/72.

SCREENING/FLOTATION TREATMENT OF COMBINED SEWER OVERFLOWS, Ecology Div.,
Rex Chainbelt Inc, for Office of Research and Monitoring, EPA, 11020 FDC,

1/72.

Cc-7


Surface: Asphalt
Initial Mass: 20 gm/sq. ft.

102 E -_
» 10
re
4
t
2 1.0 =
< - Sweeper
§ a (Wayne 450)
é S
3 107!
=
Flusher
yor? bee

C1) 2 4 6 8 10 «12 14
Relative Effort

Figure 35, Comparison of Cleaning Performances
of Motorized Street Sweeping and
Motorized Street Flushing

Iv-11


Section III

MISCELLANEOUS SOURCES OF URBAN RUNOFF POLLUTION


higher for winter months as compared with summer months. During times of
heavy snow melt, these loads were threefold the normal summertime loads.”
Indeed, recent studies have shown that 600 lb of salt, when applied to a
one-mile section of roadway 20-ft wide containing 0.2 in. of ice, will
produce an initial salt solution of 69,000 to 200,000 mg/f in a temperature
range of 10°F to 25°R, Analyses of accumulated snow and ice deposits have
likewise shown them to contain up to 10,000 mg/g sodium chloride, 100 mg/f
oils, and 100 mg/p lead.”

In addition to salt contamination, numerous special additives found in present
day deicers may create pollution problems more severe than those caused by
chloride salts. Sodium ferrocyanide, used to minimize salt caking, is quite
soluble in water and will generate cyanide in sunlight. Tests have shown
that a 15,5-mg/P solution of this additive produced 3,8 mg/g of cyanide in

30 min (the USPHS standard for cyanide in drinking water is 0,01 me/f).?
Chromate and phosphate additives, used as corrosion inhibitors, have also
been found in high quantities, A study of snow-melt collections conducted

in the Minneapolis-St. Paul area showed values of up to 1.7 mg/f hexavalent
chromium (the USPHS standard is 0,05 mg/p).?

The effects of these loadings, while not completely known, is becoming rela-
tively well recognized. The most noticeable effect of deicing salts is the
frequent damage to roadside soils, vegetation, and trees, Such drainage can
take the form of leaf scorch, defoliation, stunting, and ultimately, plant
die-off. However, in regards to man's use of water, the main effect of deicing
salts is an objectionable taste. While excessive salts can be harmful, health
hazards seem relatively rare, Serious groundwater pollution has, however,
occurred in many locations. In New Hampshire, more than 200 roadside wells
have been replaced at a cost of $200,000 due to salt contamination resulting
from highway deicing and leaching from salt storage piles. Some of these wells
had chloride concentrations exceeding 3500 mg/p .? The USPHS standard for
chloride is 250 mg/?. A survey of northern states showed a total of 13 report-
ing injury to plants, while 12 reported water contamination as side effects
from the use of salts,? Without some adoption of measures to mitigate these

III-2


CONTENTS

Section

Appendix
B

Appendix
c

Appendix
D

(Continued)
SAMPLING PROCEDURE. ......
Locality Data Collection... .
Hand Sweeping. . .... + +. s+
Hose Flushing. .......e+-.
Data Collection. ........

Sample Collection. ..... .
Sample Handling and Preparation
Procedures... 1. + ee eee
Solid Sample Preparation... .

BIBLIOGRAPHY... 1... es eee
Information Matrix. ......

GLOSSARY... 2 6 ee ee eee

VIIT

B-1

B-1
B-2
B-2
B-2
B-3

B-3
B-4


(a) Develop a unit hydrograph for the impervious portion of the study

area by using Espey's equations.

Slope (S)
Ss = 2 f£t/100 ft = 0,02
Area (A)
(5280 ft) (2640 ft) _
Atotal ~ ~ 43560 ft2 acre = $20 acres
A, = 0.55 x 320 = 176 acres
‘imp

Imperviousness (I)
I

100%

Length (L)
L = 7,000 ft

Using Nomograph of Figure 7 in Conjunction with
Figures 8 thru 11

TTM! = 27 minutes
Q = 259 cfs

T = 155 minutes
W, = i

50 37 minutes
Was = 25 minutes

The resultant hydrograph is shown in Figure 22a.

II-8


Percent of Contaminant Removal

70

10

Figure 2.

0.1 0.2 0.3 04 0.5
‘Total Inches of Runoff

Street Surface Contaminant Removal as a Function of Runoff
1-22


6. Land drainage modifications -- for reducing or eliminating the
runoff of polluted waste waters and to minimize the import of
waters containing snow and ice control chemicals

7. Reduction in indiscriminate use of chemicals -- for control of
unwanted pest infestations and the improvement of soil and
plant nytrient conditions, and

8. Management-labor relations practices -- to minimize waste col-
lection and other municipal sanitation work stoppages.

In the AVCO Corporation study,” land-use practices such as improved urban
planning and land-use regulations were stressed as important control mea-

sures for urban runoff pollution,

As a result of tests performed on the effectiveness of public works prac-
tices during the EPA-sponsored study on street surface contaminants, 1+ the
following selected recommendations were made to improve the control of urban
runoff pollution: better training of cleaning equipment operators, proper
maintenance of cleaning equipment, improved street maintenance, auto parking
controls, and improved curb design. It was also recommended that public works

departments seriously consider eliminating catch basins from particular systems.

During this study, it was revealed that the efficiency of street sweeping pro-
grams in the removal of the dust and dirt fraction of street debris is low.
The overall removal effectiveness of dust and dirt was determined to be only
50 percent. The removal efficiency of conventional street sweepers was found
to be dependent on particle size, Sweeper efficiency ranged from 79 percent
for particles 2000 microns in size to only 15 percent for particles less than
43 microns, The removal effectiveness for larger litter (i.e., paper, wood,

leaves, etc.) ranged from 95 to 100 percent,

Increased removal effectiveness of present state-of-the-art street sweepers
was shown to be possible by decreasing the operating speed or conducting
multiple passes, However, to increase the overall effectiveness from the

normal (50 percent) to 70 percent would require twice the normal effort.

v-14


C, TECHNICAL ABATEMENT

1, Improved Street Cleaning Practices

Street surface ‘contaminants, which represent a major portion of urban
land contaminants, can be partially removed by street sweeping oper-
ations prior to being exposed to runoff. A primary method of abating

urban runoff pollution is to improve existing street cleaning practices.

Municipal street cleaning practices may be improved by (1) increasing
the frequency of street sweeping and/or (2) increasing the removal

effectiveness of street cleaning methods.

Motorized street sweepers are designed to loosen dirt and debris from
street surfaces, transport it onto a moving conveyor, and deposit it
temporarily in a storage hopper, The three major types of street
sweepers include the broom-type sweeper, the vacuum=-type sweeper, and
a third type of sweeper which uses a regenerative air system to "blast"

dirt and debris from the road surface into a hopper.

Municipal street sweepers typically remove about half of the contami-
nants residing on street surfaces, The efficiency of contaminant re-
moval is related to the particle size distribution of the contaminant
material, Sweepers are most efficient in removing large size particles
while most pollutants are predominantly found in the small particle
size range of contaminant material, Street sweeper efficiency as a
function of particle size is described in Table 12.

Table 12, AVERAGE STREET SWEEPER REMOVAL EFFICIENCY

Particle Size Percent Removal
(2)
<104 17
104 ~ 246 48
246 - 495 55
>495 67

Iv-6


ST-II

‘Main Drainage Channel

SUBAREA 1

SUBAREA 2

2107

Inlet 1 Inlet 2

1. Slope of Main Drainage Channel = .01

2, Hydraulic Radius of Main Drainage Channel = 0.75 feet

{equivalent to a pipe diameter of 36 inches)

Figure 24.

Study Area of Example 8

Point of Discharge, D


S@-I

i
1 -YEAR 30- MINUTE RAINFALL (INCHES)

Cry

Figure 4,

1l<Year 30-Minute Rainfall (Inches)