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~(~ ~,t,5~~v Adequacy Items <br />1 " ,~ n ~,~/ ' SHB AGRA Project E92-7075 <br />~~~ ~V ` Pege 4 <br />i' Bi <br />The maps ta-b are contained in Attachment 5. This work indicates that in yeaz 10 <br />approxi tel 158 res in major and moderate disturbance (see plan, Attachment 5). The <br />maps a end to show areas of cover crop which aze not considered to be in final <br />4. Exhibit D - MininP Plan in Permit Application <br />Page 2 -How many trucks will be hauling material per day across Highway 66? (How many <br />85 ton and how many 25 ton?) <br />Projections of hauling activity are detailed in the Traffic Impact Analysis technical appendix <br />completed by Felsburg Holt & Ullevig in May 1993. Table 3 of that report outlines wck trips <br />projected for each month of the year and assumes hauling will occur four days per week. <br />According to Table 3, the projected number of truck trips (both empty and loaded) will range <br />from a minimum of 234 per day during a typical month of March to 380 per day during <br />December, using 25-ton haul trucks. Using 85-ton haul trucks, the number of truck trips are <br />projected to vary from 68 per day during a typical March to a maximum of 112 per day during <br />December. <br />Page 3 - It is stated that "The 4th Ridge formation contains relatively high quantities of <br />• pyrite where it is fresh and unaltered.": Please provide analyses of Fe, SO, content in these <br />rocks as well as the range in %a pyrite contained in this rock. <br />Chemical anal ses which have been co .plated to date aze presented in Attachment .The <br />analysis has not included 9b ovrite. ~~~~ ~~ _ ~`~ in / c~~c <br />• Will the pyrite material be excavated and exposed to air or water and therefore to C~uK <br />oxidation? The Division is concerned about any acid generation or potential acid mine /tiu,y.k. <br />drainage on site and possibly off site. Will the base of auy water body sit on pyritic rock? ,.j,,,,,,~'_, p <br />Only weathered 4th Ridge materials will be mined and taken to the plant. It is possible <br />excavation will expose unweathered 4th Ridge material, but unweathered material will be left <br />in place and not taken to waste rock piles. Due to the acid-base neutralization potential of the <br />4th Ridge limestone material as evidenced by the calcium carbonate (CaCO,) content, the <br />potential for net acid generation is considered minimal. Attachment 7 summarizes nine yeazs <br />of pH measurements from the existing Lyons Quarry "A" pit which includes essentially the same <br />strata as will be mined at Dowe Flats. The pit water varies from neutral to slightly basic which <br />is to be expected due to the high calcium carbonate content of the surrounding rock. Further, <br />the exposed 4th Ridge materials will be covered with topsoil and revegetated upon completion <br />of mining. <br />The plan is to mine the 4th Ridge to a minimum elevation of about 5300 feet. As encountered <br />in exploratory coreholes, groundwater is 20 to 25 feet below that depth. Accordingly, the 4th <br />Ridge materials are expected to be above groundwater. <br />AG RA <br />Earth & Environments/ Gmup <br />