Agenda Packets - 2021/07/06 - Laserfiche WebLink

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n ,_ i SCOTTLAND GREEN POND NUTRIENT ANALYSIS Part of the requirements of the Rice Creek Watershed District include an analysis of the nutrient assimilative capabilities of the wetland areas that are affected by development projects. The Scottland Green Pond project consists of enlarging an existing wetl.ands.area to provide stormwater storage for a large drainage area in central Moundsview. As such, there will be some modification to existing wet- lands and also the addition of ponding areas. Following is a breakdown of existing and planned vegetation type areas within the wetlands. a. Existing Marsh Based on our field survey, we estimate that approximately 6.5 acres of wetlands are presently on the site. The wetlands are mainly cattail marsh with an area of about 2.5 acres of floating bog. Using the nutrient assimilation values given in the watershed district's Wetlands Preservation Guideline, the present assimilative capacity is 6.5 Acres x 4.0 lbs/acre/yr = 26 lbs/yr b. Developed Pond After grading the pond, several different vegetation types are planned for the pond. The enclosed drawing shows the different pond depth areas. The floating bog area is essentially preserved with shallow water and wet -dry areas are added. The open water areas shown are the result of a compromise between the City of Moundsview and the Minnesota Department of Natural Resources. The marsh areas break down as follows on the attached figure Open Water 8.6 Acres Cattail Marsh 3.7 " Floating Bog 2.5 " Wet --Dry 2.1 The assimilative capacity of the proposed marsh -and pond area will be: 3.7 Acres x 4.0 lbs/acre/yr = 14.8 lbs/yr 2.5 Acres x 4.0 lbs/acne/yr = 10.0 IT 2.1 Acres x 12.0 lbs/acre/yr = 25.2 it Total 50.0 lbs/yr Therefore, it can be seen that the project will improve the nutrient assimilative capcity of the Scottland Green ponding area.