Encyclopedia of Environmental Science and Engineering, Volume I and II

MODELING OF ESTUARINE WATER QUALITY 723

TABLE 4

Combined sewer overflow and urban storm runoff characteristics

Constituent

Flow wtd. conc.

(mg/l)b

Mass discharge

(lb/acre/in. runoff)c

Coefficients

(lb/acre/ year)d

BOD 150 30 125

SS 325 70 600

VSS 200 45 180

HEM 50 10 38

TKN 12 3 13

NH 3 N5——

NO^3 ̃N 0.2 — —

Total
 P 5.0 1 3

Total colia 5 105 ——

Fecal colia 0.5 105 ——

Urban Runoff

Mass discharge

Coefficients

(lb/acre/in.

Constituent runoff)b

Flow wtd.

conc. (mg/l) (lb/acre/year)b

(lb/acre/in.

runoff)b

BOD 18 33 2.0 4.1

SS 77 730 45.6 17.4

VSS 25 160 10.0 5.7

HEM 2.8 — — —

TKN 1.2 9 0.56 0.26

TP 0.3 2.5 0.05 0.07

TCa 9 103

FCa 3 103

a Units are MPN/ml.

b Data from Weibel et al., 1964.

c Data from Spring Creek Project, 1970.

d Data from San Francisco, 1967.

Because of economics the pipe could be built just so big,

and at the size it could carry all the domestic wastes during

dry weather but only a portion of the wastes during wet

weather. During a large storm, the pipe would fill to capac-

ity and the flow would have to be diverted to a waterway to

insure that backups did not occur in the sewage system. For

such drainage systems, each large rainfall results in a certain

amount of material being washed into the nearest waterway.

The amount of material produced is highly dependent on the

drainage system itself, on the use of land in the drainage

TABLE 5

Quality of rural runoff

Source

Total nitrogen

(lb/acre/year)

Total phosphorus

(lb/acre/year)

Forest Runoff 1.3–3.0 0.3–0.8

Surface Irrigation

Return flow 2.45–24.0 0.92–3.88

Subsurface

Irrigation

Return flow 38.0–66.0 2.5–8.1

Urban Runoff 8.5 0.8

Source: Fruh, 1968.

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