28-14 Amend Chp. 1339 Storm Water Mgmt

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(2) Unstable soils prone to slipping or land sliding shall not be graded, ex- cavated, filled or have loads imposed upon them unless the work is per- formed in accordance with a qualified professional engineer's recom- mendations to correct, eliminate, or adequately address the problems. (q) Cut And Fill Slopes: Cut and fill slopes shall be designed and constructed in a manner that will minimize erosion and slippage. Consideration shall be given to the length and steepness of the slope, soil type, up slope drainage area, groundwater conditions and slope stabilization. The minimum final unreinforced soil slopes will have a horizontal to vertical ratio of 2:1 (the horizontal will be two times the vertical). (r) Stabilization of Outfalls and Channels: Outfalls and constructed or modified channels shall be designed and constructed to withstand the expected veloc- ity of flow from the planned post - development frequency storm without eroding. The planned post - construction velocity and flow shall include the entire contributing watershed. Velocity dissipation devices shall be placed at discharge locations and along the length of any outfall channel to provide non- erosive velocity from the structure to a water course so that the natural physical and biological characteristics and functions are maintained and protected. (s) Establishment of Permanent Vegetation: A permanent vegetative cover shall be established on denuded areas not otherwise permanently stabilized. Permanent vegetation shall not be considered established until ground cover is achieved which, in the opinion of the city engineer, has 80 percent vege- tative density over the entire disturbed area and provides adequate cover, and is mature enough to satisfactorily control soil erosion and survive ad- verse weather conditions. (t) Disposition of Temporary Practices: All temporary soil erosion and sedi- ment control practices shall be disposed of immediately after final site stabi- lization is achieved or after the temporary practices are no longer needed, unless otherwise required by the city engineer. Trapped sediment shall be permanently stabilized to prevent further erosion. The construction mainte- nance guarantee shall not be released by the City until all temporary soil erosion and sediment control practices that are no longer needed have been removed, properly disposed of and any trapped sediment has been stabi- lized. (u) Underground Utility Construction: The construction of underground utility lines or pipes shall be subject to the following criteria: (1) Trenches shall remain open for no more than five days, unless ap- proved by the city engineer. (2) There shall be no turbid discharges to surface waters resulting from dewatering activities. If trench or ground water contains sediment, it must pass through a sediment settling pond or other equally effective sediment control device, prior to being discharged from the construc- tion site or to waters of the state. (3) When discharging clean ground water care must be taken to ensure that it does not become pollutant laden by crossing over disturbed soils or other pollutant sources. 11R