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~.r.: <br />A, . <br />STATE OF .t. <br /> <br />COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1311 Sherman 51., Room 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866-3567 <br />FAX: 13031832-8106 <br /> DEPAR7'MEN'r OF <br /> NATURAL <br /> RESOURCES <br />DATE: September 12, 1997 Roy Romer <br /> Goverrar <br /> <br />TO: Dan Mathews <br />~ i <br />_ lames S. LOChhead <br />Faecutive Director <br />Michael B. LOng <br />FROM• Jim Pendleton Division DirectUr <br />RE: Roadside rte - Re a Disposal Pile - Piezometer #307 <br />(Permit No: C-81-041) <br />I have reviewed the information which you sent via facsimile to my attention. I understand your <br />concern regards the status of piezometer #307, installed on the second bench of the refuse <br />disposal pile at the Roadside mine. It is my understanding Larry Reschke informed you, during <br />your recent inspection of the pile, that this piezometer has been unusable (incapable of entry with <br />the m-scope water table depth probe) for the majority of its life. You have requested my opinion <br />whether this piezometer needs to be replaced by the operator. <br />In 1994, a series of thirty piezometers were required to be installed within the refuse pile after <br />seeps had developed above the second facial bench. The Division wanted the operator to <br />determine whether this seep was the expression of a perched seep along the surface of the bench= <br />or rather an indication [hat the entire pile was saturated to [hat elevation. The assemblage of <br />piezometers have satisfactorily demonstrated to [he Division [ha[ the seep was an expression of <br />a perched water bearing lens within the pile, probably resulting from [fie--high compaction of a <br />surface exposed to truck tire traffic for an extended period of time. Further, as the pile's <br />thickness increased and the upslope diversion of surface drainage was improved, the flow from- - <br />these seeps diminished. Finally, there has been no evidence of renewed instability of the refilse <br />saturated by the seepage. <br />No other of the thirty piezometers has indicated any potential problematic ground water <br />elevations. Nor has the refuse pile demonstrated any slope stability problems. I do not believe <br />it would be warranted at this time to require the operator [o replace piezometer #307. I <br />recommend that we require the operator to continue to attempt to monitor piezometer #307. A <br />changed condition in the future might warrant a more in depth reconsideration of [he situation. <br />cc: Lany Routten <br />doc: M:\COALUAP\piez307.wp5 <br />JP1JP <br />