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NIOBRARA <br />FORMATION <br />(Upper Cresace.w) <br />LN GQ 3 I!J�1TED <br />MMA�iiEEll11 <br />TOO HATES <br />LUMASTONE <br />' , .. 1 . <br />, <br />CARLILE <br />(Lipper ) <br />CrHSC.eus <br />COMM SANDSTONE <br />--- ,- , r- +r° ^ -,, -, <br />r,. - -- <br />ftUI HILLS SNALI <br />, . , <br />►ALE SHALE ► HIT CHALKY <br />GREENHORN <br />LIMESTONE <br />(Upper 6..lsc....) <br />eLLMESre <br />. . <br />�� <br />. >_, <br />LINCOLN LIMESTONE <br />GRANEROS <br />SHALE <br />(Upper c..lae.aua) <br />r . <br />. ' <br />DAKOTA <br />SANDSTONE <br />(Lr. .rr Cretaceous) <br />LIMPER SANDSTONE <br />. I , , <br />DWI CREEK CANYON <br />• <br />LOWER SANDSTONE <br />•.�. a - - Y <br />Blasting Impacts Assessment for the Proposed GCC Rio Grande, Inc. Quarry in Pueblo County, Colorado <br />Chemical Contamination of Ground Water <br />Most commercial explosives contain 70 to 94% ammonium nitrate, by weight. If significant <br />amounts of explosives are spilled or incompletely detonated, some amount of ammonia and nitrate <br />can leach out into ground water. The U.S. EPA ambient water quality criterion is 0.02 mg/L free <br />ammonia and the drinking water criterion for nitrate as nitrogen (NO3 — N) is 10 mg /L. At the Red <br />Rock site, if normal industry standards of care concerning clean -up procedures are used to recover <br />any spilled explosives materials like ANFO or emulsion slurry explosives, and charges are <br />adequately primed with cast - booster primers, ambient levels of ammonia and nitrates in the <br />relatively deep Dakota and Cheyenne aquifers, and the St. Charles River located more than 4,000 <br />feet from the closest blasting areas will not be subjected to any significant increases in ambient <br />levels of ammonia and nitrates. It should also be noted that aquifers below the near - surface Hayes <br />Limestone, where blasting will occur, as shown in Figure 4.1, are isolated from the Dakota and <br />Cheyenne aquifers by several impervious shale layers. The author has visited many existing <br />quarries with relatively arid environments, similar to that of the Red Rock site, and knows of no <br />significant water contamination incidents at these operations, many of which have operated for <br />over 20 years. <br />rere.aMen <br />5, • \,,.l tl or. r r 'i, , ,Ju J t,,.1 <br />Maask.r <br />'Meknes' Depth fe ten..,. <br />(N) Hn <br />Figure 4.1 -- Rock Strata at the Red Rock Site <br />Plrykol character <br />RIO GRANDE PORTLAND CEMENT COMPANY <br />RED ROCK PLANT 8 L MESTONE MINE <br />aLcbin Cnuqty, Colorado <br />EXHIBIT C -7 <br />GENERALIZED GEOLOGIC SECTION <br />REVEY Associates, Inc. Page 13 July 2002 <br />