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<br /> <br />Memo to Garv Curtiss -2- January 29 1997 <br />installation of a filter and riprap, the excavated width will <br />exceed 21'. My recollection of the access road is that there will <br />be insufficient space to install the proposed ditch at a number of <br />locations. The operator should report on the construction <br />feasibility of the ditch, and a site inspection by the Division to <br />assess the routing of the ditch may be needed. <br />The operator has presented a design for a "scale/asphalt road <br />intercept channel". Details need to be provided as to the location <br />and purpose of this structure, including the routing at the outlet <br />of the proposed intercept channel. <br />Another corrective action required of the operator in the <br />Division's 11/12/97 inspection report was to evaluate sediment <br />generation potential in the disturbed area and to design a sediment <br />control plan to minimize discharge of sediment to Deer Creek that <br />may occur during the 10 year-24 hour storm event. The operator has <br />illustrated the location of the shallow sediment basin on the third <br />quarry bench on a map, and has indicated that this structure has a <br />volume of .1 acre feet. The operator has also provided a design <br />for a spillway for this sediment basin. The operator has <br />illustrated the location of the small entrance gate sediment pond <br />on a map, and has indicated that the pond has a volume of .03 acre <br />feet. The operator has also provided a spillway design for the <br />entrance gate sediment pond. The operator has provided a volume <br />figure for an "upper sediment pond" of .2 acre feet, and has <br />provided a spillway design for this "upper pond". An "upper pond" <br />has not been observed during Division site inspections, so I don't <br />know if we have missed it, or if it is a structure proposed for <br />construction. The operator also refers to a "scale sediment pond" <br />with a volume of .34 acre feet. This "scale sediment pond" has <br />likewise not been observed during Division inspections. The total <br />capacity of the ponds referenced by the operator is .6"7 acre feet, <br />which is clearly insufficient to remove sediment from upwards of 20 <br />acre feet of runoff that would be generated in the quarry drainage <br />basin during a 10 year-24 hour storm. It is the Division's <br />opinion, as stated in the 11/12/96 inspection report, that a <br />comprehensive storm water management plan needs to be developed <br />that will route stormwater from the undisturbed area above the <br />quarry around or through the disturbed area, and that a series of <br />ditches, cross drains, detention and filtering structures need to <br />be installed in the disturbed area to minimize erosion and remove <br />suspended solids. The operator still needs to provide such a plan. <br />Necessary components of the plan include identification of the <br />location of the outlet of the existing culvert under the topsoil <br />pile, and routing of storm water flows to minimize the generation <br />of suspended solids, such as would occur in the erosion gully in <br />the fines pile located on bench #3. <br />