3.0. SR 04-24-1993 - Laserfiche WebLink

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774-6021 MAIER STEWART ASSOC. 124 P07 APR 21'93 15:13 e; Honorable Mayor and City Council February 23, 1993 Page Four 8. Temporary sediment basins shall be constructed in areas of new development to prevent sediment from leaving the construction site. Detention basins may be used for temporary sediment retention during the construction phase. The design criteria should provide permanent storage volume for sediment or the removal of sediment to restore the required detention volume. Detention areas intended to pennanently trap sediments and remove nutrients from the water shall provide excess storage beyond the lOO-year flood volumes to allQw for sediment accumulation and a normal pool elevation to exist. Sedimentation basins shall be capable of removing sediment particles of 0.02 mm diameter and larger for the average flow of the lo.year, 6-hour storm. The required surface area should be l,250 times the flow in cubic feet per second. Four feet of average depth should be available. Sediment basins shall maintain a general length to width ratio, less than 15 and greater than 10, to be constructed without baffles. Basins with a length to width ratio as low as 5 are acceptable with an inlet baffle. . 9. Grading areas shall be protected from runoff to reduce erosion. 10. Site access roads shall be graded or otherwise protected with silt fence, diversion channels or ditches, and pipes to prevent sediment from exiting the site via the access road. PrimaI)' site access roads shall be surfaced with crushed rock and extend for a distance of 100 feet beginning at existing paved surface. 11. The City shall maintain a street sweeping program to minimize sediment entering the drainage system. 12. Establishment of temporary and permanent vegetation shall be required to minimize the time that a graded area remains in an exposed condition. For example, temporary vegetation should be established within 14 days of final grading. Permanent vegetation should be established on sites that will have no construction activity for one year. 13. Erosion control plans shall be required for all land disturbance activity. The plans shall be consistent with the MPCA's Preteeti", Water Duality in Urban Areas. 14. Existing stonn drain inlets and conveyance systems shall be adequately protected frem sedimentation. . 15. Natural vegetation shall be preserved to the greatest practical extent. 16. The use of grassed waterways shall be encouraged wherever practical to maximize infiltration and trap pollutants. Grass-lined swales shall be designed to non-erosive velocities (maximum 2 feet/second) and non-turbulent hydraulic conditions.