FLOOD03246

• County: Statewide
• Community: Nationwide
• Basin: Statewide
• Title: Pollution Characteristics of Stormwater Runoff Completion Report
• Date: 9/1/1978
• Prepared By: CSU Environmental Resources Center
• Floodplain - Doc Type: Educational/Technical/Reference Information

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centages of COD, BOD, TS and SS from the storm runoff are 10.8,

5.7, 44.2, and 47.6 respectively. Thus, compared to the combined

wastewater, the storm runoffs were most significant in terms of

solids loading.

Studies in Stockholm, Sweden (Soderlund and Lehtinen, 1972)

have compared discharges from biological and chemically treated

sewage water with that from stormwater runoff. The loadings

were in kg/ha/yr and were reported for 35 persons/hectare (P/ha)

(14 P/acre) and 100 p/ha (40 P/acre). The SS loading of storm-

water was about twice as high as that of treated wastewater for

35 P/ha, and over twice that of the treated wastewater for 100

P/ha. BOD and the nutrients, however, were only a small percentage

of that reported for treated wastewater and bacteria in stormwater

were a magnitude or so less.

In Atlanta, Georgia a study (EPA, 1971) compared the

pollutant load from storm sewers with that of combined sewers.

It was estimated that the average annual BOD from storm sewer

areas amounted to 55 percent of that from combined sewers. A

one-year storm of two-hour duration yielded 7.744 and 3.940

pounds BOD/acre/hour of rainfall, respectively, for combined and

storm sewer areas. By contrast, a two-week storm of 5-hour

duration yielded only 0.694 and 0.334 pounds BOD/acre/hr of

rainfall (1 pound/acre/hr = 1.22 kg/ha/hr).

In the Detroit-Ann Arbor study (Burn, Kranczyle and Harlow,

1968) an estimate was made of total tonnage and pounds/acre dis-

charged from combined and separate systems. Table 21 shows the

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