Project Packet - Laserfiche WebLink

Home Browse Search

to provide the Applicant with substantial enjoyment of his prope1iy by providing pnvacy, security and child safety. Retaining Wall and Grading. As shown in the topographical survey, the elevation of the southern half of the Applicant's prope1iy is below the surface elevation of Bracketts Point Road. As a consequence, street stormwater has traditionally drained onto the site. To provide stormwater rate control and water quality control, the Applicant proposes to construct a retention area (i.e., an infiltration area) in the southerly pmiion of .the prope1iy. On the easterly po1iion of the infiltration area (i.e., "upland" or towards Bracketts Point Road) a stone retaining wall will be constructed to enhance the capacity of the infiltration area in a relatively flat portion of the site. A swale will be constructed to direct stonnwater nmoff from Bracketts Point Road and the prope1iy to the infiltration area. Because the topography in this area is extremely flat and only slightly above the Ordinary High Water Elevation of Lake Mi1meton.ka, drain tile will be placed under the swale and retaining wall to provide minimal gravity flow (at 0.4% slope) into the infiltration area. No outlet directly into the lake is being proposed. The retaining wall will not encroach into the lakeshore setback area, although the grading to create the infiltration area will encroach. The infiltration area and swale will be planted with native floodplain species and it is expected that the vegetation will provide some degree of water quality treatment. In addition, it is necessary to elevate the area of the driveway in the floodplain so that the Applicant may access his property during wet periods or when the elevation of Lake Mi1metonka is higher than nomrnl. The mean high water level of Lake Minnetonka typically rises by at least 7 inches during the spring and summer. The elevated area of the driveway will be held by two retaining walls on either side of the driveway entrance from Bracketts Point Road. A culve1i will pass beneath the driveway entrance and through the retaining walls to allow stonnwater to continue to flow through the swale into the infiltration area. As shown by the attached Site Grading and Drainage Plan, the volume of fill in the floodplain will be compensated by the volume of the cut into the floodplain. The holding capacity of the floodplain, thus, should not be diminished, as demonstrated in the enclosed floodplain volume calculations. The topography at the southerly end of the site together with the configuration of Bracketts Point Road as it travels south necessitates that stormwater handling be addressed in this single family residential development. The proposed variance will not impair public health or safety; but rather is expected to advance environmental concerns by handling stonnwater mnoff from Bracketts Point Road in an environmentally responsible manner. Finally, by constrncting the infiltration area together with the retaining walls and elevation of the driveway entrance, the Applicant's access to and enjoyment of his property will be enabled by treating and handling stormwater from the adjacent street in a controlled and environmentally responsible way. #2956541\2 f) ';•;,:_ ...... ;.,;"i'.•'