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Long-Term Ti 7.1.D. - Page 13 <br /> assessments are available, Permittees may choose to reprioritize trash management areas and <br /> associated control measures designed to improve trash reduction within their jurisdictions. <br /> 1.2.2 BASMAA Generation Rates Project <br /> Through approval of a BASMAA regional project in 2010, Permittees agreed to work collaboratively <br /> to develop a regionally consistent method to establish trash generation rates within their <br /> jurisdictions. The project,also known as the BASMAA Trash Generation Rates Project(Generation <br /> Rates Project) assisted Permittees in establishing the rates of trash generation and identifying very <br /> high,high,moderate and low trash generating areas. <br /> The term"trash generation" refers to the rate at which trash is produced or generated onto the <br /> surface of the watershed and is potentially available for transport via MS4s to receiving waters. <br /> Generation rates do not explicitly take into account existing control measures that intercept trash <br /> prior to transport. Generation rates are expressed as trash volume/acre/year and were established <br /> via the Generation Rates Project. <br /> In contrast to trash generation,the term"trash loading" refers to the rate at which trash from MS4s <br /> enters receiving waters.Trash loading rates are also expressed as trash volume/acre/year and are <br /> equal to or less than trash generation rates because they account for the effects of control measures <br /> that intercept trash generated in an area before it is discharged to a receiving water.Trash loading <br /> rates are specific to particular areas because they are dependent upon the effectiveness of control <br /> measures implemented within an area. Figure 2 illustrates the difference between trash generation <br /> and loading. <br /> Trash Generated — Trash Intercepted Trash Load <br /> l <br /> Figure 2. Conceptual model of trash generation,interception and load. <br /> Trash generation rates were estimated based on factors that significantly affect trash generation <br /> (i.e.,land use and income).The method used to the establish trash generation rates for each <br /> Permittee builds off"lessons learned"from previous trash loading studies conducted in urban areas <br /> (Allison and Chiew 1995;Allison et al. 1998;Armitage et al. 1998;Armitage and Rooseboom 2000; <br /> Lippner et al. 2001;Armitage 2003; Kim et al. 2004; County of Los Angeles 2002, 2004a, 2004b; <br /> Armitage 2007).The method is based on a conceptual model developed as an outgrowth of these <br /> studies (BASMAA 2011b). <br /> Trash generation rates were developed through the quantification and characterization of trash <br /> captured in Water Board-recognized full-capture treatment devices installed in the San Francisco <br /> Bay area.Trash generation rates estimated from this study are listed for each land use type in Table <br /> 1. Methods used to develop trash generation rates are more fully described in BASMAA (2011b, <br /> 2011c,and 2012). <br /> 5 <br />