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Memo 1/1 Bonestroo <br />Rosene <br />VH AnderiOc& <br />|\j| Associates <br />4. Excavation of temporary sedimentation ponds and the use of BMPs should be In place during each lot <br />construction to reduce the erosion to the adjacent wetland. * <br />. t . <br />Water Quantity <br />The topography of this site prevents the entire site to drain to a single ponding area. We offer the following <br />recommendations: <br />1. It is recommended that the impervious surfaces, (house, driveway, and yard) and any land disturbed <br />during construction be routed to drain Into the street and into the proposed ponding area. This will <br />reduce the amount of untreated runoff draining directly to the adjacent wetland. <br />2. The 100-year HWL for the proposed pond does not seem to provide sufficient freeboard for Willow <br />Road. The elevation of the low point on Willow Road should be established and submitted to city staff. <br />3. The cover for the outlet structure under Willow Road should be evaluated. <br />4. It Is difficult to determine from the grading plan whether a maintenance bench above the pond NWL Is <br />being provided. At a minimum there should be one provided around inlets, outlets, and at any point <br />where dredging operations might occur. <br />5. The ponding area should also have a 10:1 aquatic bench at the ponds NWL. The ponding area <br />Illustrated on the plans does not appear to have this feature. <br />6. The Installation of an Emergency Over Flow (E.O.F.) Is recommended for this pond. The E.O.F. <br />should provide overland drainage for the pond during storms that exceed the 100-year event, and or <br />when the outlet structure becomes obstructed. The EOF should protect adjacent homes and roadways. <br />Bonestroo, Rosene, Anderllk and Associates <br />2335 West Highway 36 # St. Paul, MN 55113# Phone:651-636-4600# Fax:651-636-1311