08/13/2003 P&Z Packet - Laserfiche WebLink

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16. Erosion and sedimentation. Give the acreage to be graded or excavated and the cubic yards of soil to be moved: acres 29.7 ; cubic yards 100,000. Describe any steep slopes or highly erodible soils and identify them on the site map. Describe any erosion and sedimentation control measures to be used during and after project construction. The proposed development site is characterized by fairly level topography. Anoka County Ditch No. 10 has side slopes approaching 12 %. Erosion will present a hazard in slope areas if soils are exposed and left bare during construction activities. The streambank area along the ditch will not be disturbed by construction. Construction of the project will disturb more than 1 acre of land and therefore will require a National Pollutant Discharge Elimination System (NPDES) permit. A likely requirement of the NPDES permit is that a storm water runoff and erosion control plan must be prepared. The plan will include the collection and treatment of runoff through grass swales, temporary sediment basins, storm water detention ponds, silt fencing, and vegetative filter/buffer strips. Furthermore, City policies and standards for controlling erosion and sedimentation will be required. These standards are consistent with the MPCA Best Management Practices for Protecting Water Quality in Urban Areas, the BWSR Minnesota Construction Site Erosion and Sediment Control Planning Handbook, and the EPA Nationwide Urban Runoff Program (NURP). Vegetative filter strips will be used around portions of the site to help control erosion. According to the Lino Lakes Handbook for Environmental Planning and Conservation Development, filter/buffer strips provide an important function in minimizing erosion, reducing direct runoff of stormwater into vulnerable ecological resources, and help sustain wildlife populations through suitable habitat. The City of Lino Lakes and the developer will continue to coordinate efforts with the Rice Creek Watershed District, MPCA, and the Lino Lakes Environmental Board to ensure potential runoff concerns are addressed. 17. Water quality: surface water runoff a. Compare the quantity and quality of site runoff before and after the project. Describe permanent controls to manage or treat runoff. Describe any stormwater pollution prevention plans. A storm water drainage system is proposed to be constructed within all the street improvements to convey runoff to proposed ponding areas and drainage swales. Favorable controls for road runoff, as well as those in adjoining property development, have been identified. The storm sewer and pond water quality and quantity controls will be coordinated in size with the needs of the proposed. development to provide required treatment and discharge rate control. The City of Lino Lakes has storm water policies and design standards that will need to be satisfied by the proposed development to reduce the introduction of pollutants to wetlands and the area waterbodies (i.e. Anoka County Ditch No. 10 and Marshan Lake). Furthermore, the storm water treatment system will need to incorporate standards and rules of the Rice Creek Watershed District that also governs surface water planning within the project area. The proposed treatment and retention system includes the creation of water quality ponds, vegetative filter strips, drainage swales, and infiltration basins. Before construction can proceed, both the City of Lino Lakes and Rice Creek Watershed District (RCWD) must issue permits to satisfy surface water runoff regulations. The rate and volume of surface water runoff will increase during storm events as additional impervious surface area is created by the construction of buildings and pavement areas. To address the anticipated increase in rate and volume of stormwater runoff, the development will incorporate storm water controls and green space areas to ensure post - development runoff rates will be maintained at regulated rates. To maximize pollutant removal efficiencies, the controls will be designed and constructed ,according to NURP, City of Lino Lakes, and Rice Creek Watershed District standards. Lakes Business Park EAW — July 21, 2003 14 Lino Lakes, MN • • •