2007-11-14 CC Packet - Laserfiche WebLink

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Describe any erosion and sedimentation control measures to be used during and after project construction. The majority of soil types within the project area do not represent steep slopes or highly erodible soils. There is one area in the north part of the project site where an eroded soil type is identified: HdC2 - Hayden fine sandy loam, 6-12% slopes, eroded. Soils on steep slopes are designated with a "D" or an "E" in their mapping symbol and generally have slopes greater than 12%. Soils on slopes greater than 12% are not identified at the project site. The locations of the soil types are shown on Figure 8. Because construction of the project will disturb more than one acre ofland, an application for a National Pollutant Discharge Elimination System (NPDES) General Permit for Construction Activities will be submitted to the MPCA. This permit requires the applicant to develop a Stonnwater Pollution Prevention Plan (SWPPP) which includes both temporary and permanent erosion and sediment control plans; the NPDES permit also requires the applicant to perform inspections and maintain inspection records. Erosion control measures to be used during construction are expected to include rock construction entrances, silt fence, rock ditch checks, temporary sediment traps, biorolls, riprap, inlet protection, temporary seeding and mulch. Initially, these erosion control devices will be placed at the downstream end of the construction limits; the devices will be installed prior to the start of any land disturbing activity. Additional devices as noted on the construction drawings may be added as construction progresses. The devices will be maintained as directed under permit requirements to maintain their effectiveness. Maintenance will be the responsibility of the Contractor. Within the timeframes stipulated in approved plans, graded areas will be paved, seeded and mulched, or covered with fiber blankets, stabilization mats, or sod. Erosion control devices will remain in place until site stabilization has been achieved and vegetation has been reestablished. Permanent strategies to control erosion and manage stonnwater are discussed in Item 17 and will include the use of constructed ponds and stormwater infiltration areas (such as raingardens) where the water can infiltrate. 17. Water quality: surface water runoff a. Compare the quantity and quality of site runoff before and after the project. Describe permanent controls to manage or treat runoff. Describe any stormwater pollution prevention plans. l\S this is a redevelopment project, the existing site is primarily dev~loped "vvith a mix of residential and commercial land uses. Construction of the medium and high density residential and mixed use commercial sites will increase the impervious surfaces and therefore stormwater runoff will increase. Proposed stormwater management measures will be designed to meet the City of Centerville, Rice Creek Watershed District (RCWD) 12