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0 i <br />Chapter 4-Site-Speci5c industrial Storm Water BMPs <br />• <br />What Is It <br />Land surfaces can be graded or graded and paved so that storm water runoff is directed away from <br />industrial activity areas. The slope of the grade allows the runoff to flow, but limits the runoff from <br />washing over areas that may be contaminated with pollutants. like conveyances and dikes, graded <br />areas can prevent runoff from contacting industrial areas and becoming contaminated with <br />pollutants from these areas. Grading can be a permanent or temporarycontrol measure. <br />• <br />I When and Where to Use It <br />Grading land surfaces is appropriate for any industrial site that has outdoor activities that may <br />contaminate storm water runoff, such as parking lots or outdoor storage areas. Figure 4.3 <br />illustrates the use of graded pavement in preventing runoff from washing over a service station <br />site. Grading is often used with other practices, such as coverings, buffer zones, and other <br />practices to reduce the runoff velocity and provide infiltration of the uncontaminated runoff, or to <br />direct pollutant runoff to storm water treatment facilities. <br />What to Consider <br />• When designing graded areas and pavement, both control and containment of runoff flows should <br />be considered. The grading should control the uncontaminated flow by diverting it around areas <br />4-9