Laserfiche WebLink
6-21-7999 7:07PM FROI•~GIHON ASSOCIATES 303 d36 93~ p_75 <br />GIHON <br />-EFFERT <br />P.f <br />r1 i~EYS AT L:\n' <br />Mr. Chuck Williams <br />Page 14 <br />June Z1, 1999 <br />Soda itself. See Letter {torn American Soda to Rio Blanco County, Colorado (Mar. 8, 1999) <br />(attached). EPA must investigate the claims made in the letter before it can issue the permit. <br />EPA simply cannot determine from these scant, stale, and possibly erroneous data <br />whether the aquifers in the area ate USDWs or not. Until it can make this determination, EPA <br />cannot fulfill iu statutory obligation to protect USDWs. 1n this case, the administrative record <br />suggests at the least that EPA should proceed with caution. <br />EPA also makes the sweeping conclusion that the "semi-confining" Mahogany Layer <br />is sufficient to prevent upward migration of solutions front the mining area. The record is devoid <br />of data or facts to support this conclusion; indeed, the DEIS contradicts it. In the same <br />paragraph of the DSOB in which EPA concludes [hat the Mahogany Zone will prevent <br />migration, EPA states further: "Even though the rich oil shale composing the Mahogany Zone is <br />itself quite impermeable, the presence of fractures and dissolution features within this zone may <br />permit some vertical exchange of water between the two aquifer systems." DSOB at 7- Thu <br />statement flatly contradicts the conclusions found just before it. In addition, this statement and <br />the rest of the analysis found in the DSOB ignore two key environmental issues raised in the <br />DEIS: (1) injection of water under pressure; and (2) [hc potential for subsidence. <br />f <br />The technical success of the Yankee Gulch project depends upon the injection- <br />under pressures of between 300 to 700 pounds per square inch-of water heated to temperatures <br />between 300 and 420 degrees F. See DSOB at 1. Nowhere d«s EPA. address the possibility that <br />injection of fluids under pressure could force contaminated solutions upwards through the <br />Mahogany Zotve into the Upper.Aquifet. <br />The issue of subsidence is relevant to EPA's permitting decision because the mine <br />plan could cause subsidence and result in additional fracturing of the Mahogany Zone. <br />Additional fracturing, combined with the constant injection of hot water under pressure, could <br />create conditions that may result in contamination of USDWs that overlie the injection Zone. <br />For all its technical and legal weaknesses, even the DEIS documents the possibility <br />chat injected water could force contaminated water up into the Upper Aquifer and further into <br />the alluvial aquifer system and even could cause a discharge to surface water. See DEIS at 4.15. <br />EPA simply ignored these parts of the DEIS in its permitting evaluation. EPA must withdraw the <br />draft permit and evaluate these important issues before moving forward, <br />The SDWA d«s not allow EPA to guess-as it seems to have done hers-about <br />whether injection will affect ground water or whether USDWs occur in the vicinity. The statute <br />requires that EPA operate the program to prevent degradation of USDWs resulting in violation <br />14 <br />