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Memo to'PCPC <br />Re: SUP No. 1999-002 <br />September 13, 1999 <br />Page 13 <br />With removal of the limestone, sandstone; and a 25% to 30% swell factor for the <br />overburden, upon reclamation, the surface elevation in the quarry area will be <br />: <br />lowered an average of 40: feet. <br />Blasting Methods <br />It is anticipated that blasting events will occur Mo to three times p,er month. A <br />detailed geological investigation precedes each blasting event and a'.ows.for <br />much tighter control over the blast pattern and charge, which mitigates ground <br />vibration and atmospheric shock.waves. Monitoring of ground movement and <br />shock waves will ensure they are within guide!ines issued by the US Bureau of <br />Mines. <br />Blasting will be conducted by `a federally and State licensed professional blaster. <br />The expected blasting agent will be a mixture of ammonium nitrate and fuel oil <br />(ANFO) and a high explosive booster agent. This material will be transported to <br />the site as blasting is required. No explosives will be stored on site. <br />The Blasting Plan must be approved by the Mined Land Reclamation Board's <br />Division of Minerals and Geology prior to initiating such activity on site. <br />Erosion Protection and Sedimentation Control. <br />Storm water will be diverted from the active quarry areas via diversion channels <br />maintained at the perimeter of the production panels. Silt fences, constructed of <br />small hay bales or an equivalent material, will be applied in those areas where <br />storm water may run off roadways or other bare soil locations. Runoff will be <br />diverted to an impoundment to allow for settlement and then discharged to the <br />St. Charles River drainage. <br />The high walls at the northern edge and the sides of the earthen incline will be <br />permanently stabilized with slopes,not exceeding 7.0% for rock and. 30% or less <br />for soils. Final high walls will be_sloped . 3:1 and stabilized to prevent erosion <br />using a gec-textile material containing the prescribed seed mixture. It is <br />proposed that the impoundment of surface water be-contained in the <br />northwestern. most corner of the initial box cut. The impoundment will be <br />designed to contain. all the runoff, anticipated from a 100-year rainfall event. The <br />impoundment will migrate with the mining as it moves to the south. Water within <br />the:ir-hpoundment could be used for dust control when available'.