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Ms. Katie Larsen <br />06/06/2024 <br />Page 2 <br />Madinah Lakes – Concept Plan - Engineering Review <br />This would include coordinating with Anoka County with regards to the proposed <br />roundabout at Sunset Avenue (CSAH 53) and Main Street (CSAH 14) at the northwest <br />corner of the site and integrating the associated stormwater management features (ponds, <br />ditches, etc.) into the design of the development. <br />Most of the site is within the City’s General Floodplain District (FEMA Zone A) and, <br />according to a previous Geotechnical Report, groundwater levels range from 4-feet to 9- <br />feet in depth. The applicant will be required to meet all City of Lino Lakes ordinances and <br />RCWD rules for surface water management. <br />The proposed Madinah Lakes development is in the Marshan Resource Management Unit <br />(RMU) according to the City of Lino Lakes 2018 Local Water Management Plan (WMP). <br />The WMP noted several issues within the Marshan RMU, including the following issue <br />pertinent to the then Robinson Property: “ACD 10-22-32 is ineffective for future urban runoff <br />volumes.” (Appendix B). A strategy for mitigating this issue specific to the Robinson <br />Property noted in the WMP was: “Proposed master community plan for sod fields” <br />(Appendix B). In addition, the WMP identified existing and future flooding and pollutant <br />loading concerns within the RMU, including Marshan Lake and adjacent wetlands and ACD <br />10-22-32 (Table 2-21). <br />WMP Goal 4.1 is to “Provide adequate storage and conveyance of runoff to protect public <br />safety and minimize property damage.” To address the City’s flooding concerns in <br />accordance with this goal, implementing stormwater rate and volume control practices <br />where feasible throughout the Robinson Property will be critical. Sufficient freeboard must <br />be provided for proposed structures above the seasonal high groundwater levels and <br />floodplain elevations in compliance with City Ordinance Chapter 1102 (Stormwater, Erosion <br />and Sediment Control) and RCWD Rule C (Stormwater Management). Ditch conveyance <br />capacity along Sunset Avenue (CSAH 53) and Main Street (CSAH 14) should be <br />maintained and street entrance ditch crossings should utilize large and/or multiple pipe or <br />box culverts. City and RCWD regulatory floodplain management requirements will also <br />need to be met (See Floodplain below). <br />WMP Goal 7.2 is to “Ensure that well-planned, quality residential...development <br />accommodates the City’s projected growth needs and occurs in a manner that also <br />conserves and enhances the City’s natural resources and amenities.” To assist the City in <br />meeting this goal, the applicant should provide the following for the proposed stormwater <br />ponds and lakes: 1) shoreline geometry that more closely resembles natural bodies of <br />water, 2) buffers for natural vegetation and high-water level bounce, 3) areas for future <br />maintenance activities (e.g., pond/lake dredge material removal and dewatering) and 4) <br />differentiation of the water quality and quantity function, goal, and design of both. <br />Comments: <br />1. Based on groundwater levels, infiltration basins are not likely on site, filtration or <br />sedimentation basins appear to be more appropriate. Care should be taken to <br />design systems that avoid floatation concerns within the high groundwater levels. <br />2.All stormwater features must be easily accessible for future maintenance, the <br />current concept plan shows an isolated basin on the far east side of the site that <br />would require either access through a private road or via a long overland <br />distance to a public road.