CCP 01-21-2003 - Laserfiche WebLink

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I I. I I I I I I I Ie I I I I I I I. I I According to the February 2002 Local Storm Water Management Plan (LSMP) for the City of Arden Hills, the AUAR study area is located within the Valentine Lake district in the Rice Creek Watershed District (RCWD). There are 13 wetlands in or near the study area. Seven of the wetlands are affected by the existing and future drainage from the proposed project. These seven wetlands include Wetlands A, C, D, E, F, G and L and are shown in Figure 10. The City's storm water management plan lists the seven wetlands and Valentine Lake as Tier 3 water bodies, which indicates that the intended uses do not include direct human contact with the water. Tier 3 water bodies include all DNR protected lakes, wetlands, and watercourses not included in Tiers 1 and 2. Tier I consistently supports swimming and Tier 2 lakes are capable of supporting swimming or having significant public use. Based on the site and utility plan and storm water analysis provided by Rehder and Associates, Inc., the AUAR study area can be divided into six unique drainage areas as shown in Figure 10. The areas are defined by topographic boundaries, storm drain alignments and where water discharges from the site. The areas are addressed individually within this section. For most of the existing site, runoff from pavement (parking lots and roadway surfaces) is carried via storm sewer to the receiving wetlands and carries with it the sediment and pollutants associated with these types of areas untreated to the water body. A few areas drain into municipal storm sewer cither via overland flow or via storm sewer connections. Area I, which will not undergo any site plan changes at this time, flows to the existing storm sewer system on Lexington Avenue to the east. Area II drains into Wetland A, which crosses the southern property line in the southeast quadrant. Area III drains to Wetland D within the study area at the northwest comer of the intersection of CR F and Fernwood Avenue. Drainage from Wetland A flows into Wetland C outside of the study area and subsequently flows into Wetland D. Wetland D then discharges to the south through a culvert under CR F. Area IV drains to Wetlands E, F and G. These are linked wetlands, which eventually drain out of the AUAR study area north along Hamline Avenue. Area V flows into Wetland I and then out of the site to the northwest The northeastern portion of Area V (the Building 0 site) is not expected to undergo any site plan changes at this time. Area VI, which will undergo only slight site plan changes at this time, drains onto the adjacent roadways and into cxisting storm sewer at the northeast corner of the study area. According to the Comprehensive Drainage Survey Maintenancc Plan and Ponding Recommendations prepared for the City of Arden Hills (dated May 1999), there are no planncd regional stOlID water ponds in or ncar the AUAR study area. Design criteria for on-site storm water treatment are listed below. . The total phosphorous removal efficiency for each pond or pond network must be at least 65 percent. (LSMP) (3uidant Campus Master Plan Final AUAR and Mitigation Plan - 21 - January 2003