10-05-2020 Council Work Session Packet

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WS – Item 2 WORK SESSION STAFF REPORT Work Session Item No. 2 Date: October 5, 2020 To: City Council From: Diane Hankee PE, City Engineer Re: NE Lino Lakes Drainage Area Improvements Background The surface water in the Northeast Area of Lino Lakes has a restricted ability to drain and is considered landlocked. This condition leads to minor flooding and inhibits the ability to complete site improvements within this area. The Northeast Drainage Area includes nearly 1,300 acres, attached is a project location map. The area has existing field drains from the early 20th Century that have limited ability to drain. These agricultural drains are now at capacity and are incompatible with future development within the watershed. In addition, the agricultural drains do not provide any water quality benefits to the receiving waterbody, Peltier Lake. The Northeast Area of Lino Lakes is bound by Main Street to the south, the City of Hugo to the east, and Peltier Lake to the west, and Rehbein Street to the north. A majority of this watershed currently drains to the southeast to Clearwater Creek via field drains. Clearwater Creek is impaired for aquatic life and has had a history of significant bank erosion problems. Multiple alternatives were vetted to address the drainage needs for the area. The project alternatives were refined with input from land owners, potential developers, neighboring communities, the Rice Creek Watershed District (RCWD), the Minnesota Pollution Control Agency, US Army Corps of Engineers, and the Minnesota Department of Natural Resources. A Comprehensive Surface Water Management Plan (CSMP) was required by RCWD for watershed approval. The CSMP and the associated surface water modeling includes regional water quality best management practices (BMPs), stormwater volume and rate control improvements, and a new outlet to Peltier Lake. The CSMP also includes design standards for future developments in the Northeast Area. Peltier Lake is impaired for nutrients and the new system will improve the quality of water entering the lake. The proposed project includes a new stormwater conveyance system, and multi-purpose regional stormwater management facilities. The project will be implemented in phases in coordination with development in the area. Phase 1 includes the construction of the outlet to Peltier Lake and phase 2 includes a crossing of the system under I-35E to extend the conveyance system to the east side of the freeway. As part of the approved Watermark Master Development Agreement, the City is obligated to complete phase 1