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SWMP Guidance • • Page 5 3) Sediment and erosion prevention: The plan shaII identify areas which, due to topography, activities, or other factors, have a high potential for significant sail erasion, and identify measures taken to limit erosiars. 4) Other pollution prevention measures: The plan shall identify any other structural and non- structural measures for stormwater quality control on-site. In each case where stormwater pollution potential exists, appropriate preventive measures must be taken and documented. Best biana~ment Practices: There aze several defuritions of BMPs. Two examples aze as follows: B~IPs aze defined as physical, structural, and/or rnanagerial practices that, when used singly or in combination, prevent or reduce pollution of water. (State of Washin,on, 199?) Bps can describe a wide range of tnanagement procedures, schedules of activities, prohibitions or practices and other tnanagemeni practices ... ByfPs also include operating procedures, treatment requirements and practices to con¢ol plant site runoff, drainage from raw materials storage, spills or leaks. (EPA, 1991) "Nonstructural" BIvIPs aze mainly defuritions of operational or trtanaeerial tec'nniques. In addition, there aze a multitude of "structural" BMPs which should be considered, depending upon the industrial activity. Structural ;include physical processes ranging from diversion structures [o oillwater sepazators to retention ponds. Some BIvIPs may be listed under more than one section of the SWIvIP (for eeample, secondary containment may come under both BMPs and spill plans); these can be cross-referenced, instead of repeating the entire description. When selecting BbIPs, the most important ones to evaluate first aze those which limit the source of the pollutant. It is much more efficient, from both a cost and environmental standpoint, to preven[ the pollution in the first place than to clean up contaminated stormwater. For eQample, a BMP requiring that any vehicle maintenance Plat involves fluid exchange must take place indoors, results in the removal of a pollutant source (i.e., oil/hydraulic fluids) from possible contact with stormwater. Once source reduction BMPs have been evaluated, then more costly options, such as mitigation of impacts or stormwa[er treatment, should be considered, if necessary. The BbIPs selected aze up to the judgment of the individual permittee. However, it is important to keep in mind [hat a fully implemented SWIvIP will constitute compliance with Best Available Technology (BAT) and Best Conventional Technology (BCT), as mandated under the Federal Clean Water Act. Basically, this means that, in order to comply with your permit, the appropriate measures must be taken in keeping with the pollutant(s) involved and the risk potential at the facility. A list of common BbiPs is provided in Appendix C, ranked in order from non-structural to structural, which is also, in most cases, least expensive to most expensive. These aze many other BNfPs available as well. For more specific information, see the List of Available Documenu, as provided by the Division. This includes ordering information for local and national BiVfP manuals.