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<br />WS – Item 3 <br />WORK SESSION STAFF REPORT <br />Work Session Item No. 3 <br /> <br /> <br />Date: June 5, 2017 <br /> <br />To: City Council <br /> <br />From: Diane Hankee, City Engineer <br /> <br />Re: Culvert Maintenance ACD 10-22-32 Branch 2 <br /> <br /> <br />Background <br /> <br />At the May 22, 2017 City Council meeting staff was directed to prepare information <br />regarding the Anoka County Ditch (ACD) 10-22-32 Branch 2 culvert and associated <br />wetland located north of the Lino Lakes Elementary school on the Kociscak parcel. <br />Several property owners residing on Diane Street, adjacent to the wetland, attended the <br />meeting and voiced their concerns over the high-water levels of the wetland and the <br />condition of the existing culvert. A location map is attached. <br /> <br />ACD 10-22-32 is managed by Rice Creek Watershed District (RCWD). The RCWD <br />prepared a Repair Report in 2010. The culvert, one of several along the ditch, was <br />replaced in 2013 with a 24 inch diameter HDPE (plastic pipe) at the existing ditch <br />elevation. The base flood elevation of the wetland (Pin Oak Lake) is 904.54 based on <br />RCWD modeling. A map from the RCWD Repair Report is attached showing the ditch <br />system. <br /> <br />The residents, City staff, and the RCWD ditch inspector found that the culvert was being <br />blocked by beaver activity. Prior to the City Council Meeting on May 22, 2017, City <br />staff received permission from Kociscak (the property owner) to clear the ditch and <br />culvert. Since that time, City staff has continued to monitor the culvert. Additionally the <br />RCWD obtained a special DNR permit for trapping the beavers. On May 26, 2017 two <br />beavers were removed from the area of blockage along the ditch. Since that time, the <br />water level of the wetland has receded approximately 1 foot (within 5 days). <br /> <br />Questions were also raised regarding a wetland mitigation project constructed with the <br />Bluebill Ponds development, in 2004. The Bluebill Ponds development created wetland <br />mitigation of 0.96 acres north of the ditch. This work was permitted by RCWD and the <br />Army Corps of Engineers. The wetland mitigation provided for additional storage and <br />improved flow of water from the basin. It did not add runoff to the basin. <br /> <br />Residents also noted that stormwater ponds within Wollan Estates required cleaning. <br />Within the next 3 years, the City will perform maintenance on the Wollan Estates <br />ponding systems as part of the City’s annual surface water management project. This <br />project would be completed during the winter months when the ice is thick enough to <br />allow construction equipment access and activity.