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<br />Work Scope (cant.) <br /> <br />and 2020. This will provide for an easy comparison of where nondegradation standards <br />may not be satisfied. <br /> <br />Once complete, the loading assessment spreadsheet model will be validated using water <br />quality monitoring data where available. It is important to note that the absolute values are <br />not as critical in the loading assessment as are the relative differences between the years. <br />The loads should be relatively close to the actual values, however, to provide a reasonable <br />estimate of BMP effectiveness. <br /> <br />Task 2. Analysis <br /> <br />Task 2a. Estimate the Change in Pollutant Loading and Volume from Baseline to <br />Current Conditions <br /> <br />Once the model has been constructed and validated, load changes will be assessed for TP, <br />TSS, and volume. Load reductions will be applied to each development in which treatment <br />devices (ponds, swales, infiltration basins) have been incorporated. Those areas that do not <br />provide sufficient treatment will be identified. This task identifies all of the rules, codes and <br />ordinances under which development took place during the 1988 to current period as well <br />as the projected rules under which new development will take place. Wenck anticipates <br />. that City staff will identify which developments occurred without stormwater management <br />practices. <br /> <br />Given the number of treatment devices in the City, modeling each of the devices would be <br />time consuming and ultimately result in greater detail than needed for this study. Instead, <br />approximately ten devices will be modeled to determine representative treatment reductions <br />from various land uses. City and Wenck. staff will identify two or three examples of single- <br />family residential, multi-family residential, commercial, and industrial development. <br />PondNet or P8 computer models will then quantify the device treatment reduction for each <br />of the ten. <br /> <br />The load reduction from the treatment devices will then be applied external to the model. <br />Additionally, areas of the City that are current high priorities can be incorporated into the <br />model allowing the City to expend resources where they are most critical. <br /> <br />Finally, pollutant removal due to street sweeping will be applied external to the model. Our <br />experience with nondegradation plans indicates that removal records due to these practices <br />can have a significant positive impact on meeting nondegradation. This step helps to <br />clarify the features that need to be addressed in the nondegradation plan so that the proper <br />credit is given for City activities that have been implemented to protect water quality. In <br />concert with quantifying street sweeping loads, Wenck recommends that the city conduct a <br />grain size analysis of sediment removed from sweeping to determine what portion of the <br />swept load comprises TSS and TP. <br /> <br />Task 2b. Project Change in Pollutant Loading and Volume from Current to Future <br />Conditions <br /> <br />This task is very similar to Task 2a except the analysis compares 2020 to 2004 conditions. <br />The same load reduction from treatment devices determined from Task 2a will be used for <br /> <br />T:\0598\OOINonDegradation ProposaJ\Work Scope. doc <br /> <br />13 <br /> <br />e{~Wenck <br />