Environmental Engineering FOURTH EDITION

244 ENVIRONMENTAL ENGINEERING

deflected away from the site or channeled through the site in such a way that sedi-
ment erosion is minimized. Even with erosion control devices in place, runoff from
construction sites usually contains higher concentrations of suspended sediments than
runoff from established sites, so it is important to protect existing storm drains by
placing filter bags, straw bales, silt fences, or other filtering devices around nearby
storm drain inlets.
The final step in controlling nonpoint pollution from construction sites is to reveg-
etate the site. This should be done as quickly as possible, and may involve several
steps if the site is to be landscaped. Professional landscaping often requires bringing
in additional topsoil, grading the landscaped area, as well as seeding and planting,
fertilizing, and mulching. If the landscaping process is delayed, a temporary soil
cover should be used to protect the valuable topsoil and prevent erosion and sediment
pollution.

Urban Nonpoint Source Pollution

In 1983, the Environmental Protection Agency published the results from the Nation-
wide Urban Runoff Program (NURP), a comprehensive study of the water quality in
storm water runoff at 81 sites in the United States (USEPA 1983). The NURP study
revealed that storm water runoff from urban areas contained higher concentrations of
many different kinds of pollutants, especially metals, nutrients (nitrogen and phospho-
rus), oxygen-demanding substances, and suspended solids. Subsequent studies have
added pathogenic microorganisms, oil and petroleum hydrocarbons, pesticides, and a
variety of synthetic organics to the list of urban storm water pollutants. Table 11 -5 lists
the major categories of urban pollutants and typical watershed sources for each type

Although urban runoff has long been recognized as a major source of pollution,

regulatory control of urban nonpoint sources of pollution has lagged behind point

source regulations. During the past decade, however, many countries have begun major

efforts to reduce or eliminate pollution in storm water runoff from urban areas. In 1990

the USEPA introduced new rules that direct cities with populations of at least 100,000

to begin managing storm water runoff as point source discharges that require NPDES

discharge permits. In December 1999, this requirement was extended to include cities

with populations of at least 10,OOO.

The current storm water NPDES permits have six required control measures:

public education and outreach, and public participatiodinvolvement to inform citi-

zens about the sources of storm water pollution and encourage citizen participation

in developing and implementing pollution control measures; illicit discharge detec-

tion and elimination to identify and Correct illegal discharges; construction site runoff

control and post-construction runoff control to reduce soil erosion and other types

of pollution associated with construction activities; and pollution preventiodgood

housekeeping to reduce pollution in runoff from municipal operations.

Although we often think of pollution abatement as requiring a technological

approach, pollutants in storm runoff can also be reduced through planning and

of pollutant.