Stormwater Pollution Control: Structural Measures

Combinations of storage and wet-weather treatment, integrated with dry-weather treatment facilities and nonstructural control measures on an area-wide basis, are found to provide the greatest and most cost-effective control of storm-water pollution. Case studies of three very promising, constructed and operating structural measures for controlling combined sewer overflow pollution demonstrate these concepts. Information on the design, operation, performance and costs of these facilities is provided and compared to guide future planners and designers. In Seattle, Washington, computerized control of in-line storage offers operational flexibility and inexpensive storage. At Saginaw, Michigan, off-line storage/treatment integrated with in-line storage and dry-weather treatment has achieved high performance at moderate costs. At Mount Clemens, Michigan, physical and biological wet-weather treatment processes promise very high treatment levels for combined sewage, if needed.