10/29/2003 Env Bd Packet - Laserfiche WebLink

Home Search

ANALYSIS Rice Creek Watershed District (RCWD) The RCWD reviewed the proposal on October 8, 2003 and issued a CAPROC (Conditional Approval Pending Receipt of Changes). Findings of the Rice Creek Watershed include the proposal to relocate the mainline of Anoka County Ditch #72, and reconstruction of Branch 1, within the project's parcel boundary. Findings show no increase in the runoff rates from the site onto adjacent properties. The ditch relocation will remain in a piped condition. RCWD will maintain a 50 -foot easement on either side of the pipe. There are no proposed wetland impacts associated with this project. There is no proposed flood plane fill for the site. An acceptable erosion control plan has been submitted. Grading, Drainage and Erosion Control Many bioretention /raingarden areas are incorporated into a stormwater treatment train. The treatment train is designed to capture at least a % inch rainfall event. Stormwater from proposed parking /impervious areas is channeled through curb cuts into these depressional areas. A P8 phosphorous load model was run for the site. The model demonstrates a 19% reduction of phosphorous outflow for phase 1, and a 16% outflow reduction for phase 2. The P8 model shows an increase in site phosphorous inflows. This is because of atmospheric dust particles attached to phosphorous particles settling on impervious surfaces. The rain garden design directly captures these additional phosphorous accumulations from the impervious surfaces (for a 3/ inch rain event). Minnesota Land Cover Classification System (MLCCS) MLCCS data shows nothing significant on the site. The site however, is immediately adjacent to a natural resources lake. The lake boundary next to the church site is indicated as cattail marsh, with sedge meadow inclusions, lake sedge and tussock sedge. In addition, water willow (unique plant) is found along the shoreline of the island and in cattail inclusion areas along the shorelines in this area. Proposed best management surface water practices should help to attenuate effects of nutrient loading into the lake, and the effects on vegetation present immediately off site. The church is proposing to use native plants in vegetative swale, bio- retention, infiltration, and ponding areas. This is another recommended BMP.