5.5. SR 08-06-2007 - Laserfiche WebLink

Home Browse Search

Work Scope (cant.) reduction and developing recommendations for the City based on the differences between the two. This includes an evaluation and recommendation of appropriate BMPs to meet any necessary loading reduction requirements. The fmal step is to document the study approach, findings, and recommendations, and submit the study to the MPCA for their review. The Wenck approach to each of the following tasks identified by the City is described in more detail below: Task 1. Loading Assessment Task I includes the collection and processing of GIS and modeling data for development of the loading assessment for baseline (1988), current (2004), and future (2020) land uses. Steps within Task 1 include obtaining development land use, soil type and land cover and quantification of loading for the three assessment points. Task la. Gather Data This task includes compiling all necessary GIS and water quality data needed for the analysis. Data includes land use and land cover, soil types, topography and any other data needed for the assessment. Wenck staff understands that Sherburne County provides GIS services to the City and therefore assumes that 1988 and 2004 land use data is available electronically from the County. Task lb. Quantify Changes in Landuse and Imperviousness in the City of Elk River Land use and land cover analysis will focus on impervious surfaces in the watershed. Data will be acquired from available land use coverages, LANDSAT images (satellite images of the earth's surface) provided by the MPCA, and available aerial photos (current and historical). Wenck staffwill meet with City staff to confirm the land use assumptions that will be used to defme the year 2020 development conditions. If City land use maps do not provide adequate information, LANDSAT images will be corrected using the current and historical aerial photographs to reduce scatter and error in the imperviousness estimates.' Task Ie. Construct Spreadsheet Model for 1988, Current and 2020 Conditions The spreadsheet model for the City of Elk River will use the change in the land use to develop loading in 1988, current (2004), and 2020 conditions. Runoffvolumes will be calculated using runoff coefficients obtained from literature and applied to specific land use types. The fmal step is to quantify the change in land use and imperviousness in the City paying close attention to land use types under conversion. For example, conversion from agriculture to urban land is very different than converting upland forest to urban land. It is not reasonable to conduct the load assessment by subwatershed since they have not been delineated within the City. Therefore, Wenck suggests meeting with City staff in order to identify critical "areas" ofland use change for each time period. For example, section numbers may be used to divide parts of the city into areas that developed dramatically between 1988 and 2004 or areas that are expected to develop between 2004 T:\OS98\OOINonDegradation ProposallWork Sco~e.doc 12 ..,~Wenck