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. ~-- 6Ir. Steven G. Renner Colorado (lined Land Reclamation Division 6larch 12, 1986 Page Two Response: The groundwater evaluation contained in the approved permit application did not predict dewatering of over- burden located stratigraphically above the pit. Thin prediction xas based upon actual pump teat data obtained from xella com- pleted is the Karr North area several thousand Peat north of 79- 2. Pump testa also indicated very low permiabilities and storage coefficients for the overburden strata. Although no inflows of significant amounts of groundwater have been observed in the "720" pit adjacent to 79-2, several small fractures and slips are evident in the pit walls. These features, combined with lox storage coefficients sad low permiabilities could result is the slow drawdowa observed at 79-2 without any significant pit in- flows. Another possible cause for the drawdown observed at 79-2 could be reduced recharge. The "720" pit cute off moat of the drainage area which contributes to recharge o! the overburden strata east of the pit. Additionally, the overburden stockpile is situated over a portion of the recharge area, thus reducing inflow. Finally, disturbance associated with mining the "720" pit, by its nature, reduces infiltration and increases runoff. These three factors, which all contribute to recharge reduction, could account for the drawdowa observed at 'Nell 79-2. 2. Comment: Well DH-4, xhich was destroyed, map be re- placed by an existing well is the vicinity of DH-4, as proposed by Kerr Coal, provided that the replacement well is completed in the same stratigraphic unit as DH-4. The Division requests that the completion data be submitted is order to verify the place- ment. Response: During the first scheduled groundwater moni- toring period is the spring of this year, an attempt will be made to recover DH-4. In tha event it can be recovered, monitoring will continue ae outlined in the approved monitoring plan. Otherwise, DH-4 will be deleted from the monitoring plan sad replaced with another well in the same vicinity, if possible. Any change in the monitoring plan with respect to DH-4 will be requested through a technical revision proposal. 3. Comment: Kerr Coal Company should submit to the Divi- sion data which confirm the broken casing of Well 79-26. Specif- ically, at what depth is the casing broken, the nature of the damage, and how this damage prohibits sampling. RegFonse: Well 79-26 has a broken or damaged casing approximately 70 feet, slightly above the static water level. The nature of the damage is unlmown, but it does obstruct the well sufficiently to prevent the passage of a well sampling tool,