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~. COLOWYO COAL COMPANY L.P. 5731 State Highway 13 Meeker, Colorado 81641 (970)824-1572 (970) 824-1598 FAx James A. Kiger Senior Environmental Engineer August 14, 1997 Mr. Byron Walker Environmental Protection Specialist Colorado Division of Minerals and Geology 1313 Sherman St., Room 215 Denver, Colorado 80203 Re: Colowyo Coal Mine (C-81-019) Streeter Fill Monitor Well Dear Mr. Walker: ~/= III IIIIIIIIIIIIIIII ~ Cofoa-yo Cool Company L,'P. ~;° RECEIVED AUG 1 8 1997 Division of Mineta(s ~ baolo9Y This letter serves as a follow up to my August 13 and August 14, 1997 telephone notifications to the Division regarding the Streeter fill well. As you know four wells have been drilled into Streeter fill, all located on the 6,900 bench. The September 25, 1981 CTUThompson, Inc. report describes the results of the May 1981 monitor well establishment for the first two wells. In 1986 the plastic casing of the initial two wells failed because of normal spoil settling and two new wells were reestablished using steel casing. The initial CTL/Thompson's findings and conditions noted during the original 1981 well establishment were essentially mirrored in the subsequent 1986 well reestablishment. We currently have two functioning monitor wells; 1) the north well and 2) the south well. The north well was completed to the bottom of the fill (formerly Streeter Canyon) and has been monitored quarterly for the occurrence of a water level in the base of the fill. The depth of the well to the bottom of the original Streeter Canyon is approximately 240 feet. This well has always been dry. The south well is shallower and was completed to a perched water zone encountered at approximately the 118' depth. CTLlThompson believed the perched zone corresponded to water being trapped at the 6,800' level spoil dump during fill construction. Water levels were monitored consistently at a depth of 111' later in 1981. Just recently, on August 12, 1997 we lowered a probe into the north monitor well and encountered an unexpected indication of water at the 118' level. Interestingly, we could also hear water cascading into the pipe from an unknown source. We also probed the south well and found the perched water level still in existence at the 111' level. We speculate that a casing pipe joint weld may have failed at the 118' level of the north well allowing the perched water to leak into the north well. We checked for a water level in the north well and found it to be fluctuating between 162' and 195'.