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Chapter 3: Natural Resources and Drainage | 10Otter Lake Road Master Plan <br />A regional system as proposed has numerous advantages over smaller, individual stormwater management <br />BMPs as sites develop. It takes the burden off site developers to meet the restrictive rate limits set by <br />RCWD and allows them to develop with the standard requirements seen in other regions of Lino Lakes. <br />This system also allows for high-level flood management. As development occurs, more runoff will be <br />generated, potentially raising flood elevations at lower-elevation locations of the region. With this regional <br />system, these flood elevation increases can be anticipated and incorporated into site designs at an <br />early stage. It allows developers to understand what outlots and freeboard requirements will be needed <br />based on area flood conditions. The regional system will also enhance and protect the wetlands used <br />as stormwater storage. The main drawback of a regional system is the cost to the City to construct and <br />maintain it. Parts of the system will need to be built before development can occur and therefore will <br />require an initial investment from the City. In addition, potentially developable land will be needed for the <br />system, somewhat reducing buildable area in the region. The city has established a trunk surface water <br />management charge to recover these costs. <br />Approval of this drainage system will be regulated by RCWD. The watershed is setting the rate control <br />and flood condition requirements and regional plan approval will be needed in order for specific sites to <br />develop without the highly restrictive rate limits. In addition, improvements proposed for Wetlands 4, 7 <br />and 8 within the system will require approval from the Wetland Conservation Act Local Government Unit <br />and the US Army Corps of Engineers. The pipe alignment under I-35E has been approved by MnDOT and <br />is under construction as of Fall 2022. <br />Drainage <br />The City has worked with its consultant, WSB, to create a regional drainage system to serve the study <br />area. This regional system will provide rate control as well as flood storage for stormwater within the area. <br />Under existing conditions, the study area is functionally landlocked, only outletting via the draintile of the <br />Main Trunk and Branch 8 of Anoka County Ditch 55. Stormwater from the site ultimately reaches Peltier <br />Lake, which has a TMDL for nutrient loading. Due to a combination of this TMDL and the very limited flow <br />capacity of the draintiles, Rice Creek Watershed District (RCWD) has set restrictive flow limits on proposed <br />development that routes to the draintile system. WSB is proposing an outlet pipe under Interstate 35E, <br />routed to the Watermark development to the west, ultimately reaching Peltier Lake. This pipe will allow the <br />area to avoid the restrictive limits of the draintile system and no longer function as a land locked basin. <br />While this regional system will provide ultimate control of flows coming out of the area, it is not proposed <br />as water quality treatment for the sites in the area. All sites will be required to meet RCWD’s standard <br />stormwater management requirements, including water quality, volume, and peak rate control; infiltration <br />and filtration BMPs will be suggested for site water quality treatment. These site-specific stormwater <br />systems will then outlet to the proposed regional system. <br />The system primarily consists of three water storage areas, two existing wetlands and a constructed wet <br />pond. See the Drainage and Natural Resources map on the previous page for proposed system layout. <br />Outflows from site-specific stormwater systems will be routed to one of these storage areas and then <br />through the rest of regional system from there. Storage areas are proposed to be interconnected with a <br />combination of culverts and open ditches. The final and lowest stage of this regional system will be a 0.6- <br />acre wet pond. This pond will have an outlet control structure with a sluice gate to limit flow rates under <br />I-35E and close when needed if Peltier reaches flood stages as required by RCWD.