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No design or street grades are currently available for County Road 40. The preliminary grading plans show assumed grades that work well for the development plan. It is anticipated that the grading for the road would be done under a Sherburne County project. X. STORMWATER MANAGEMENT Stormwater management for the proposed development will be provided by conveyance of runoff into 14 stormwater basins. The houses and street will drain to backyard swales and catch basins and then to a series of proposed ponds. The ponds have been designed to not exceed the existing 2-year, 10-year and 100-year outflow rates for the site. The ponds have been designed to NURP standards requiring retention for the 2.5" design storm with a 10:1 bench at the normal water level. The lowest floor elevations of the house pads are designed to be at least one foot above the 100-year design storm peak elevation. Emergency overflow for the ponds is noted on the grading plans. The pond design includes outlet control structures with submerged outlet pipes for skimming. Most of the soils have a low water holding capacity and relatively high rate of water transmission. The soils in the area are very deep — most are greater than 60 inches in depth — and the average depth to the water table is over 29 feet. The existing drainage to the northeast discharges into a wetland which outlets to Trott Brook. Existing drainage to the southeast is to a wetland. Existing drainage to the west is to wetlands and then to Trott Brook. The proposed drainage areas will follow the existing drainage patterns. The normal water level and the 100-year high water levels are noted on the grading plans. Best Management Practices will be utilized to control erosion during construction and to restore vegetative cover on all disturbed areas. XI. TRAFFIC ACCESS AND TRAILS The major access to the development would be from County Road 40. The proposed alignment cuts across the northeast corner of the project and continues south along the east project boundary. County Road 40, or Davis Street NW, is currently a gravel street. Discussion with Dave Schwarting, Sherburne County Engineer, indicated that some federal funds should be available in about a year for upgrading the road. The road would not be upgraded until development generates the traffic to demand the upgrade. They are expecting city participation in the form of right of way, storm sewer, and curb and gutter. The initial phases of the development would get access from the existing County 12 F:\ENG163300\264\REPORTS\River Park Narrative.426.doc