01-06-2014 Council Packet Special Meeting

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Item #01- Special Council Meeting - 01106114 File #13-3638 & 13-3639 [Total Pages 99] loadings, including any effects on, or required expansion of, municipal wastewater infrastructure. 2) If the wastewater discharge is to a subsurface sewage treatment systems (SSTS), describe the system used, the design flow, and suitability of site conditions for such a system. 3) If the wastewater discharge is to surface water, identify the wastewater treatment methods and identify discharge points and proposed effluent limitations to mitigate impacts. Discuss any effects to surface or groundwater from wastewater discharges. The type of wastewater that will be generated will be primarily of domestic uses. No specialized commercial or industrial waste will be generated. An MPCA hazardous waste generator permit will not be required. Based on preliminary analysis from the septic design team, the lots will be served by individual mound -style SSTS systems. The design flow is based on 600 gallons per day per dwelling. The mound systems will not discharge directly to any aquifer or surficial groundwater area. The use of the mound system provides the maximum amount of surficial soil treatment and minimizes risk of contamination by groundwater sources. The sites will be placed at a sufficient uphill distance from any wetland or muck type soil. Figure XXXX shows anticipated drainf eld locations and typical mound system cross section. ii. Stormwater - Describe the quantity and quality of stormwater runoff at the site prior to and post construction, Include the routes and receiving water bodies for runofffrom the site (major downstream water bodies as well as the immediate receiving waters). Discuss any environmental effects from stormwater discharges. Describe stormwater pollution prevention plans including temporary and permanent runoff controls andpotential BMP site locations to manage or treat stormwater runoff. Identify specific erosion control, sedimentation control or stabilization measures to address soil limitations during and after project construction. The proposed stormwater management system will be designed to limit peak runoff to existing flow rates based on the 1, 10, and 100 -year 24-hour events. Approximately 2.0 acres of filtration stormwater management devices will filter or infiltrate the first 1 inch of runoff as to provide acceptable water quality management. The proposed stormwater drainage routes will closely follow existing drainage patterns both in rate and volume on an average annual basis. Figure XXXX displays the current stormwater management plan concept. The filtration devices will be sized to meet required MCWD volume management standards based on infiltration or filtration. it is the goal of the project to work with Minnehaha Creek Watershed staff to restore the onsite wetlands and remaining open areas , through the creation of conservation easement areas throughout the site. A nearby water body, Forest Lake, requires a TMDL based on nutrients. The proposed stormwater management plan will reduce the overall TP to this lake by providing filtration and infiltration BMPs compared to existing conditions of allowing uncontrolled runoff from golf course turf areas, where excess fertilizer and high nutrient -laden runoff is common for runoff leaving the golf course site. All newly constructed impervious surfaces will be treated by stormwater BMPs before routing downstream to existing wetland or water features. At a minimum, there will be a SWPPP that will address both construction BMPs and permanent BMPs that will be in place before, during and after major site grading operations. The SWPPP will contain an Erosion Control Plan, which details specific BMPs and shows the locations, both temporary and permanent, that will address page 7