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(VII) "Daub & Ass~ates feel that the annular ceme~ requi rements as <br />well as the cement inside the 8 5/8" casing are not necessary." <br />(VIII) "The drill hole abandonment plugging gel located bet•,veen the top <br />of the cement plug at approximately 1775' and the base of the <br />cement surface plug at 65' (Figure 2) will effectively stabilize <br />the hole. In addition, the plugging gel will prevent ve rtical <br />movement of groundwater as well as seal the drill hole." <br />RESPQNSE #2 <br />These continents and their supporting reasons were discussed extensively <br />during the negotiations to grant an additional 1-year extension of rule <br />authorization for the Pilot Phase of the nahcolite mine project. This <br />extension was granted witFi the stipulation that Wolf Ridge Corporation (!d RC) <br />submit detailed monito ring plans for assessing the allegations concerning <br />mud-gel performance and plugging & abandonment proposal adequacy. <br />Further reiteration of these assertions, without supporting field data <br />from Pilot Project operations, is pointless. Decisions regarding the <br />Underground Injection Control (UIC) Class III permit requirements will take <br />these assertions into account. However, if additional data are needed, draft <br />permit conditions will be written so as to incorporate these needs. Please <br />refer to the EPA letter ckited July 22, 1986, for an indepth discussion of <br />current expectations concerning results obtained from the Pilot Project. <br />COMMENT #3 <br />This comment made it very clear that WRC believes that the available <br />evidence indicates the hydraulic gradient to be downward. <br />RESPONSE #3 <br />We feel that this cormnent was adequately addressed under RESPONSE #1 of <br />the EPA letter dated December 17, 1986. <br />CQht4ENT #4 <br />The commenter requested that any reports, which demonstrate the hydraulic <br />gradient to be upward, be presented as evidence. Also, the potential for <br />casing failures was discussed. <br />RESPa~SE #4 <br />The Water-Resources Investigation.Open-File Report 82-637, by O.J. Taylor <br />(1982), entitled "Three-Dimensional Mathematical Model For Simulating the <br />Hydrologic System in the Piceance Basin, Colorado ,provides conceptual <br />hydrogeologic information that suggests that the gradient could be upward. <br />However, we recognize that specific data is much more reliable than general <br />concepts. <br />As far as the commenter's discussion of well failure, our position was <br />made clear under RESPONSE #4 of the EPA letter dated December 17, 1986. <br />-3- <br />