Agenda - Council - 04/13/2021 - Laserfiche WebLink

Home

Record of Decision — Riverstone South Environmental Assessment Worksheet Response The culvert, ditch, and drainage permit comments are noted. Riverstone South will not drain to MnDOT right of way. The drainage from Riverdale Drive and Bowers Drive to the MnDOT right of way is outside the EAW project area the scope of the EAW. However, II'� OT drainage permit(s) will be obtained prior to construction of Riverdale Drive and the Bowers rive cul-de-sac. The outlet of the "lake" was shown on the Grading Plan included in Appendix A of the EAW. If the water level gets high enough, the "lake" will outlet overland to the southeast, toward the infiltration basin in the southeast corner of site. Permits Any use of or work within or affecting MnDOT right of way requires a permit. rmit will be required for the new Riverdale Drive street connection to Highway 10 and the for the removal of Bowers Drive connection. Response Comment noted. Minnesota Pollution Control Agency Water Resources Since the Project will disturb 50 acres or more and discharges to the Mississippi River, which has construction -related impairments and is also classified as a Scenic and Recreational and Restricted water, the Stormwater Pollution Prevention Plan (SWPPP) for the Project will require submittal to the MPCA prior to obtaining National Pollutant Discharge Elimination System/State Disposal System General Construction Stormwater permit (CSW Permit) coverage. The EAW does not discuss additional erosion and sediment control best management practices (BMPs) required during construction for special waters identified as restricted. The Project will need to implement parts 23.9, 23.10 and 23.11 of the CSW Permit and include the applicable requirements in the SWPPP. The primary stormwater treatment for the Project appears to be the proposed ponds, including one pond referred to as a 26 foot deep "lake" to be constructed on the site. The "lake" will not meet MPCA stormwater treatment system requirements. A pond constructed to treat stormwater can be no more than 10 feet deep per CSW Permit requirements. The CSW Permit requires that 1 inch of the water quality volume is treated via a volume reduction method, such as infiltration, unless site conditions prohibit per one of the reasons listed in the CSW Permit. A wet sediment pond is not a volume reduction practice. The MPCA recommends the Project designer contact MPCA construction stormwater engineering staff prior to submitting their permanent treatment plans to the MPCA. The Project Proposer is strongly encouraged to utilize infiltration along with green infrastructure practices to mimic the natural hydrology of the site and reduce runoff. Stormwater can also be harvested and reused for irrigation. 3