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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removal efficiency for COD at 48 percent, BOD at 46 percent, and

suspended solids at 4 percent. These efficiency estimations are

based on the fact that the total pollutant load from a munici-

pality will include the stormwater runoff pollutant load as well

as the pollutant load introduced by the sewage treatment plant.

It is implied then that even though pollutant removal efficiencies

for secondary sewage treatment plants are high, the overall

pollutant removal efficiencies are low when stormwater runoff is

also considered as a pollutant source.

A study in Tulsa, Oklahoma (EPA, 1974) has estimated the

annual load of pollutants entering the area receiving streams.

This is seen in Table 20, where the annual storm sewer discharges

are compared with the annual load from treatment plant effluents.

Although the storm sewer discharges contributed only 20 percent

of the annual BODS to the area receiving streams, this source

contributed 85 percent to the annual SS. One should note that

the COD contribution was higher; 31 percent compared to only 20

percent for BODS' This gives an indication that the material

in the storm sewer discharges would therefore be more slowly

oxidized than that in the treatment plant effluent.

Several investigators have reported waste loadings. However,

they seem to differ somewhat in ways of reporting their results.

DeFi11ipi and Shih (1971) have calculated waste loading, both

for combined wastewater and storm runoff, in terms of pounds per

minute. Assuming that combined wastewater and storm runoff makes

up the total amount discharged to the nearest stream, the per-

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