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Mr. Joe Carpio - 3 - May 11, 1987 analysis of the complete highwall backfill scenario results in a static factor of safety less than 1.3, then the highwall need not be completely backfilled, An alternative backfilling plan then needs to be proposed for the portal bench area and access road cut to arrive at an optimal backfill configuration that allows for backfilling of the exposed coal seam with a minimum of 4 feet of non-toxic, non-combustible fill and which provides for the maximum achievable stability for both the fill and the remainder of the exposed highwall, The stability analysis for the proposed backfilling scenario should be submitted. The backfilling plan should also incorporate a basic cut and fill balance. ii. Once a backfilling and grading plan for the portal bench area has been mutually agreed upon, the permit application text and appropriate maps will need to be revised accordingly. Any extraneous information or discussions regarding backfilling plans other than the approved plan should be removed from the text to eliminate confusion. Application Section 2.06 (Rule 2.06.8- Alluvial Valley Floor) 8. Mining related effects to the Hay Gulch alluvial valley floor (AVF) and mitigation steps need to be addressed (see Point 3 under this section of the PAR). Information was submitted in the revised permit application regarding ground water monitoring but not sufficient to completely address the Division's concerns. Maps 7, 8 and 11 indicate that a "Surface water monitor point" will be located in the AVF west (down gradient) of the sediment pond. La Plata Coal needs to address the following issues. a. A diagram depicting the proposed well completion methods and materials; b, the proposed location of this well on the appropriate maps; c. the proposed method of determining aquifer transmissivity in the vicinity of the well; and d. discussion of the anticipated impacts, if any, to the AYF from water detained in the pond, B. Additional concerns remaining from the PAR and new concerns Application Form 1. This concern relates to Point 8b on Page 2 pertaining to surface ownership. The revised page specifies surface ownership in the permit area is 100 percent private. A review of revised Map 1, however, depicts a portion of the proposed permit area is owned by the Ute Mountain Tribe. La Plata Coal needs to modify this response to clearly show the surface ownership for private and for Indian.