Ordinance - #14-09 - 09/23/2014 - Laserfiche WebLink

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Section 117 -390 (10) is hereby amended as follows (additions indicated as underline, deletions indicated as strike - tough): Section 117 -391 (6) a. is hereby amended as follows (additions indicated as underline, deletions indicated as ctriko through): (b) Stabilization, and an NOT has been submitted to the MPCA. Once the identity of the responsible party is known, the SWPPP must be amended to include this information. (11)Training documentation: The knowledgeable person(s) named in the SWPPP shall be trained in accordance with the current General Construction Stormwater Permit requirements. (10) Precautions to be taken to contain sediment when working in or crossing water bodies. a. Unless precluded by moderate or heavy snow cover (Mulching can take place if a light snow cover is present.), stabilize all exposed inactive disturbed soil areas within 100 feet of any water of the state, or within 100 feet any conveyance (curb, gutter, storm sewer inlet, drainage ditch, etc.) to a water of the state with sod, seed or weed free mulch. This must be done, if the developer will rk has not worked the area for seven days on slopes greater than three feet horizontal to one foot vertical (3:1), 14 days on slopes ranging from 3:1 to 10:1 and 21 days for flatter slopes. Section 117 -392 is hereby amended as follows (additions indicated as underline, deletions indicated as strikes): (a) The applicant shall install, construct, or pay the city fees for all stormwater management facilities necessary to manage increased runoff from development. !! _ increased_ Hydrologic and hydraulic design calculations must be submitted for the pre- development and post - development conditions for the 2, 10, and 100 year events as well as the 10 day snow melt event. Such calculations shall include: (i) description of the design storm frequency, intensity and duration, (ii) time of concentration, (iii) Soil Curve Numbers or runoff coefficients, (iv) peak runoff rates and total runoff volumes for each watershed area, (v) infiltration rates, where applicable, (vi) culvert capacities, (vii) flow velocities, (viii) data on the increase in rate and volume of runoff for the design storms used, and (ix) documentation of sources for all computation methods and field test results. These predevelopment rates shall be based on the last ten years of how that land was used. Accelerated channel erosion must not occur as a result of the proposed land disturbing or development activity. An applicant may also make an in -kind or a monetary contribution to the development and maintenance of community stormwater management facilities designed to serve multiple land disturbing and development activities undertaken by one or more persons, including the applicant. Sizing of stormwater basins shall be based upon: (1) For basins that are not land locked — Available storage volume shall be based on 100 -year return period (7.1 inch Atlas 14, Anoka County), 24hr duration, SCS Type II storm with average soil moisture conditions (AMC 2) (2) For land locked areas — Available storage volume shall be established by estimating the surface elevation resulting from a 100 year/ 10 -day runoff or 100 year /10 -day snowmelt, whichever is more restrictive. In the snowmelt scenario, frozen soils shall be assumed (CN =100). The methodology