08-01-2022 Council Work Session Packet

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aALLIANT ENVIRONMENTAL ASSESSMENT WORKSHEET II Robinson Sod Farm PAGE 13 stormwater runoff. Identify specific erosion control, sedimentation control or stabilization measures to address soil limitations during and after project construction. Pre -Construction Site Runoff The existing runoff from the project site likely contains sediments, pesticides, fertilizers, and other nutrients from the existing agriculture land. The site drains to the system of public and private ditches that exist across the property. Post -Construction Site Runoff The land use on the project site will change from agricultural to residential use. The estimated impervious surface for the PUD concept plan is 50 acres and the estimated impervious surface for the yield plan is 62 acres. All impervious surfaces will be mitigated through required stormwater treatment. During construction, there will likely be an increase in runoff from suspended solids, heavy metals, and oil/grease. After construction, the runoff from the residential site will be typical of suburban development with the increase in impervious surfaces and maintained lawn/landscape areas. It is anticipated that the proposed constructed stormwater management system will aide in limiting the increase in runoff volume and associated pollutant transport. The stormwater basins proposed on site will be constructed at logical discharge points of the site to provide temporary treatment, prior to construction stormwater leaving the site. Infiltration is not feasible on the site due to the site's high water table; therefore, other stormwater ponding methods will be used to meet the stormwater requirements of the site. Large stormwater basin features will be provided for floodplain mitigation. Stormwater runoff quality and quantity will be designed to meet the requirements of the City of Lino Lakes, Rice Creek Watershed District, and MPCA National Pollutant Discharge and State Disposal System (NPDES/SDS). Stormwater and Erosion Control BMPs Prior to construction, the project proponent will be required to submit an application to the MPCA for coverage under the NPDES/SDS General Permit since the project will involve the disturbance of more than one acre of land. In addition, the City of Lino Lakes and Rice Creek Watershed District will review and accept these plans prior to the start of construction. Best management practices (BMPs) will be installed prior to and maintained throughout construction to reduce erosion and sediment loading into stormwater runoff. This will ensure that potential adverse effects from construction -related sediment and erosion will be reduced in the surrounding area. To confirm that the BMPs are effectively reducing erosion and sediment loading, the BMPs will be inspected once a week or within 24 hours after each rainfall event that exceeds 0.5 inches. Some of the main BMPs that will be implemented on the construction site include: Installation of silt fence and other perimeter controls prior to initiation of earthwork and maintenance of these controls until ground cover has been established on exposed areas. Construction of temporary sediment basins in areas proposed for stormwater ponds. The development of these basins for permanent use will follow construction. Periodic street cleaning and installation of a rock construction entrance to reduce tracking of dirt onto public streets.