Agenda - Council - 12/14/2010 - Laserfiche WebLink

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PROPOSED DEVELOPMENT The proposed development consists of a new multistory assisted living building and associated parking, landscaping, plaza areas and site utilities. The site lies between Sunwood Drive and Civic Center Drive and is adjacent to the existing Ramsey Municipal Parking Ramp located in the "COR" development (F.K.A. Ramsey Town Center) in Ramsey Minnesota. EXISTING SITE CONDTIONS The project consists of vacant land and is comprised of approximately 1.85 acres. The site has been mass graded and prepped for development as part of the Ramsey Town Center development. Site drainage eventually is routed through the City's storm water system to a series of regional ponds. JURISDICTIONAL BODIES AND REQUIREMENTS The City of Ramsey and Lower Rum River Watershed Management Organization (LRRWMO) have jurisdiction over stormwater runoff from proposed development at this site. The LRRWMO is the review agency for both the City and the Watershed Management Organization. The City requires the removal of at least 80% of total suspended solids. To meet this requirement, BMP's must be designed to treat the 1" rain event per the City of Ramsey as a method of pretreatment prior to entering the City's stormwater conveyance system. Onsite stormwater conveyance is to be deigned to handle the 10 -year rainfall event by utilizing the rational method. EXISTING SITE DRAINAGE PATTERNS The site is currently undeveloped and the site is generally flat with minimal elevation differential. The site is gently sloping from west to east. Storm sewer catch basins in the surrounding roadways serve as potential connections for stormwater conveyance. PROPOSED ON -SITE STORMWATER MANAGEMENT The design goal of the proposed drainage plan is to follow existing drainage patterns, provide water quality treatment to at least mandated levels. Since rate control is currently handled by regional ponding provided by the City, no onsite rate control is necessary. The proposed stormwater management plan will provide the required water quality pretreatment through the utilization of hydrodynamic separators designed to handle the peak runoff rates from the 1" event. Onsite storm sewer has been designed to convey the 10 -year rainfall event. Details pertaining to these systems have been included both with this report and as shown on the submitted drawings. This project will share the treatment facilities with the easterly adjacent site due to the shared access location and points of connection for storm water. Since the storm drainage systems are utilizing a shared system for the majority of each project, the rates summary and pretreatment summary are inclusive of both projects. A separate narrative and plans for the Senior Living project adjacent to this site can be referred to for additional information. Project No. UWA10002 Suite Living at the COR Stormwater Narrative L AN D F OR M December 3, 2010 1