Laserfiche WebLink
<br /> <br />Mr. Darry Ferguson -2- February 18, 1993 <br />MAPS• <br />The sediment control map, 5-1, needs to be reaccomplished <br />utilizing the topographical map created by Air Photo Surveys. <br />The new map needs to include the: <br />1. New Coal Permit Boundary <br />2. Drainage areas delineated for each pond <br />3. Locations and sizes of all culverts <br />4. Location of all existing and proposed sediment control <br />structures. <br />5. boundary of the proposed gravel pit operations. <br />6. Locations of all Small Area Exemptions (if any). <br />The Maximum Disturbance map, 5-6, needs to be reaccomplished on <br />the Air Photo Surveys Topographic Map showing the maximum pit <br />disturbance as well as the maximum disturbance associated with <br />the gravel pit operations. Include all permit boundaries and <br />label all 10 foot contour intervals. <br />Map 5-4, Final Reclaimed Topography should also be reaccomplished <br />on the Air Photo Survey map and indicate the expected Final <br />Reclaimed topography to include the proposed final gravel pit <br />final topography. Permit boundaries for both operations and 10 <br />foot contour intervals should be indicated on the map. The <br />permanent stream channel reconstruction should be indicated on <br />this map, to include riffles, pools, and the meandering course <br />the channel will be designed for. <br />Sediment Control: <br />As noted in the cover letter, the Type II storm precipitation <br />amounts for the 10, 25, and 10 year events are 3.75, 2.80 and <br />2.25 respectively. This combined with the 33 acres of new <br />disturbance by the proposed gravel pit operations will <br />necessarily require the reverification and/or redesigning of the <br />sediment control structures listed below. <br />For all ditch designs that require modification, please provide <br />the following information: <br />a. Slope and hydraulic length of ditch. <br />b. Typical cross section to include sideslopes, width of <br />channel, designed depth of flow, and height of <br />freeboard. <br />c. Storm event associated with the ditch design. <br />d. Weighted soils cover complex number. <br />e. Time of concentration. <br />f. Calculation flow in CFS and velocity in Fps. <br />g. D50 of riprap if required. <br />h. Drainage acreage associated with each ditch. <br />