4.3 SR 03-20-2023 - Laserfiche WebLink

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The Facility is designed to ti^eat an average dry weather design flow of 3.98 million gallons per day (MGD), an average wet weather (AWW) design flow of 4.54 MGD, and a peak hourly wet weather fZow of 7.27 MGD. Based on the AWW design_flow, the Facility is designed for a five-day carbonaceous biochemical oxygen demand of 203.8 milligrams per liter (mg/L), a total suspended solid of 263. 7 mg/L, a total phosphorus of 7.2 mg/L, and a total Kjeldahl nitrogen of 36.0 mg/L. The Facility consists of inechanically cleaned bar screens, an influent Parshall flume, vortex grit removers, two anaerobic selector tanks for phosphorous removal, six extended aeration activated sludge cells in three pairs, three final clarifiers, six effluent sand filters, and UV disinfection. The Facility also adds chlorine for filter maintenance, sulfur dioxide for removal of residual chlorine, and ferric chloride for phosphorous removal. Biosolids treatment consists offour aerated storage tanks (aerobic digesters), which is then processed in a screw press to produce a biosolids cake which is landfill disposed. " Construction of new sanitary sewer lines will be required to service the project but no expansions to the City's YVWTP are anticipated to be required. The location of the Elk River WWTP is illustrated on Appendix A— Figure 9. 2) If the wastewater discharge is to a subsurface sewage treatment systeins (SSTS), describe the system used, the design flow, and suitability of site conditions for such a system. N/A 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. �/I 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 runoff from 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 and potential BMP site locations to manage or treat stormwater runof£ Identify specific erosion control, sedimentation control or stabilization measures to address soil limitations during and after project construction. The quality of existing stormwater runoff fi^om the project is typical of forested land. Stormwater runoff flows fi^om upland areas to lower elevations on site as sheet flow where it generally gets conveyed into the large wetland complex located near the center of the site. This wetland ultimately outlets into Ti^ott Brook. Page 10