08-04-25 - City Council Work Session Agenda

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• Divert upland drainage areas to prevent runoff from entering the excavated basins or into the work areas. • Installation with dry soil conditions is critical to prevent smearing and compaction. Schedule work for periods of dry weather. • In the event that the sediment is introduced into the BMP during or immediately following excavation, remove sediment prior to initiating the next step in the water quality basin construction process. • Temporary erosion protection or permanent cover over exposed soil shall be initiated immediately and completed no later than seven days after an area is no longer being worked. • Realignment of the Anoka County Ditch (ACD) system 10-22-32 and private ditches may be required as development occurs to meet future drainage requirements and allow for efficient development of the study area. After Construction The proposed future development within the AUAR study area will require compliance with the stormwater rules and standards of the City of Lino Lakes, the Rice Creek Watershed District, and the National Pollutant Discharge Elimination System (NPDES) Stormwater Permit for water quality, volume control, rate control, floodplain management, erosion control, and maintenance/monitoring. As required by Chapter 1011 of the City of Lino Lakes code of ordinances, development projects within the AUAR study area will be required to provide stormwater BMPs to manage the rate, quantity, and quality of the stormwater runoff. The National Pollutant Discharge Elimination System (NPDES) Stormwater Permit requires treatment of 1-inch of runoff for the new impervious area since more than one acre of disturbance will occur. Additionally, the post -development discharge rates shall be less than or equal to the existing runoff rates for the 2-, 10-, and 100- year, 24-hour rainfall events, as required by the Rice Creek Watershed District. RCWD Rule C: Stormwater Management requires that proposed developments will provide 1.1 inch of volume reduction over the proposed impervious surface coverage for the development through a combination of infiltration/filtration/reuse BMPs. The treatment volume is reduced by a total phosphorus removal factor based on BMP type as stated in Table C1 of the Rice Creek Watershed Rules (effective 1/1/2025). Additionally, RCWD requires public linear projects to provide treatment for the greater of 1.0 inches over the new impervious or 0.5 inches over the new and reconstructed impervious surface. There is no total phosphorus removal factor for public linear projects. Treatment is currently planned to be provided through a distributed approach across the project area. Local water quality basins will be installed along with each proposed development followed by larger detention areas, as needed, to provide rate control for multiple proposed developments as well as provide compensatory storage for floodplain mitigation. The detention areas then outlet to the greenway corridors to convey stormwater discharge downstream through naturalized areas to the main discharge points in the south -southeastern portions of the study area. Floodplains The study area includes large areas of FEMA Zone A floodplain and Rice Creek Watershed 100-year floodplain. The areas of floodplain generally align with the FEMA floodplain being more expansive across the project site. The FEMA Zone A floodplain does not have a base flood elevation associated with the mapping Lino Lakes Main Street - AUAR 46 July 2025 Page 54 of 617