Agenda - Council - 06/14/2005 - Laserfiche WebLink

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tributary o f the Mississippi River. Although the volume of storm water entering the Rum River may increase, the rate at which it is discharged will not exceed current pre-developed rates. Proposed development storm water management system(s) will meet and/or exceed MPCA requirements. Erosion control and sedimentation measures will follow the MPCA Best Management Practices (BMP), including the use ot'silt fences, sediment basins, gravel construction entrances, and timely turf restoration of graded areas. Topsoil placement will be required as the site develops. Boulevards will be restored after small utility placement. During construction approximately 60 acres will be graded or excavated and approximately 250,000 cubic yards of soil will be moved. This calculation is based on 60 acres and an average depth of 2.5 feet. Additional overexcavation may need to be done to remove any lead or polynuclear aromatic hydrocarbons (PAlls) deposited on the site when it was in use as a shooting range, as discussed in Wenck and Associates' Response Action Plan for the St. Anthony Gun Club. Grading will be limited to roadway construction, storm water ponds and house pads. Soils from the cut areas will be used in the fill areas to create a balanced overall site. BMPs will be used for erosion control including ponds, topsoil re-spread, turf establishment, silt fences, rock construction entrance and erosion control mats or wood fiber blankets. BMPs will be implemented as soon as possible to mitigate erosion and sediment, which is required for all land disturbances. Land disturbing activities shall occur in increments so that adequate BMP control can be provided throughout all phases of construction. In all areas outside of the construction area, the existing vegetation shall be preserved to provide, a permanent vegetative cover. Silt fences will be installed down gradient from construction areas and wherever runoff from the construction area discharges from the site. Grading will be nfinimized in wooded areas and slopes will be flattened in graded areas as much as possible to prevent erosio~n and sediment deposits. The design of thc site will reserve some open space adjacent to sensitive wetland areas. Wooded areas along the wetland will be preserved, where possible, to provide wildlife habitat area and to protect the wetland. Street widths, setbacks, and building types are designed to minimize their impact on the environmentally sensitive areas of the si re. As part of the platting process, an Erosion and Sediment Control Plan and a Storm Water Pollution Prevention Plan (SWPPP) will be submitted for review and approval. The developer must also obtain and comply with National Pollutant Discharge Elimination System (NPDES) permit requirements, including the SWPPP. There are no steep slopes (greater than 12%) on the site. According to the Soil Survey of Anoka County, soils on the site are Mc (Histosols), Rf(Rifle mucky peat), NyA (Ny-more loamy sand, 0 to 2 percent slopes), NyB (Nymore loamy sand, 2 to 6 percent slopes), NyC (Nymore loamy sand, 6 to 12 percent slopes), Me (Meehan sand), Is (Isan sandy loam), and Ma (Markey muck). The distribution of these soil types is shown in Figure 4. There are no highly erodib[e soils on site. The only potentially highly erodible soil on the site is NyC (Nymore loamy sand, 6 to 12 percent slopes), which is considered not highly erodible based on typical slope percentages and length for dete~qninations made in the NRCS office. Soil inspection and compaction testing by a licensed engineer will be conducted on all lots where filling is required, in accordance with the approved grading plan. Soil stabilization will be employed throughout the plat on an as needed basis as determined by the City of Ramsey to ensure the integrity of the soils. a. Compare the quantity and quali~ of site runoff before and after the project. Describe permanent controls to manage or treat runoff. Describe any stormwater pollution prevention plans. The proposed discharge will be collected into a sto~ water management system prior to being discharged at or below existing flow rates into the wetlands and ditches'on site.. The wetlands and ditches emp~ into Trott Brook, and then into the Rum River, a tributary of the ~ississippi ~ver. A Store Water Pollution Prevention Plan will be created and implemented ~ part or' the improvements process. Temp~ sediment and erosion control me~ures will utiltize vafio~ BMPs.d~ng.the construction of the improvements,· and pe~anent fea~res Such ~ detention ponds and gr~scd swales will be ~ed for 'flg:w rate control and water quali~'pu~oses. Excavation ofpon~ng areas on Lhe site will provide sedimentation and rate control for sto~ water generated by this development. The rum)Jif will be managed by directing the street runoff to combination sedimenff retention b~ins excavated in upland are~ o ~the site. From the ponding are~, the run0'f~ will be directed to the existing and created wetlands located throughout the site. These wetlands will allow the water to drain to the existing ditches within the site.