2012-06-20_PERMIT FILE - C2010089A (10)

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burden zone transmissivity and hydraulic conductivity values in the NHN area are low to very low, (see Tables 7 -5 and 7 -6 in Appendix 2.04.7 -2 of this application). The overburden and under- burden aquifers have the higher values and the coal aquifer has the lowest transmissive properties. There is approximately one order of magnitude range in the transmissivity and hydraulic conductivity values for the overburden, coal and under- burden aquifers. This suggests that there is a high degree of spatial variability within the aquifers. Storage coefficients for the various stratigraphic zones vary from about 10 to10 for the overburden and the coal /under- burden zones respectively. Transmissivities (T) for overburden vary from a low of about 13 ft /day to a high of about 58 ft /day at GW -N9 (located within the NHN permit area). T values for the coal zone vary from 2.4 to 6.0 ft /day and the T values for under- burden vary from about 3 to 88 ft /day. The backfill monitoring hole (GW -N27) was completed in the fall of 1987. A short term specific capacity and transmissivity test was conducted at the time of water quality sampling at Well GW -N27. A K (hydraulic conductivity) value of 40ft/day and a transmissivity value of 261 ft2 /day was determined (see Table 7 -5 in Appendix 2.04.7 of this application), indicating that the transmissivity in the back fill at this location is 4 to 5 times higher than that of the overburden. The saturated thickness of backfill at this location is about 6.5 ft,(see hydrograph for hole GW -N27 in Appendix 2.04.7 -1 of this application). The aquifer characteristics (production potential) of the three stratigraphic zones indicate that they are marginal at best for domestic use and totally inadequate as a source for irrigation water. Baseline Ground Water Quality Prior to drilling the nine new ground water monitoring holes (see Map 2.04.7 -1 for locations of monitoring holes GW -N47 through GW -N55), the planned hole locations, completion techniques, water quality sampling schedules and the water quality sample parameters were discussed with CDRMS for their input and guidance. Samples for groundwater quality analysis were collected on a quarterly basis from eight of the nine holes; however, monitoring hole GW- N55 has been nearly dry to the point that collecting samples from that hole is not possible. Water quality sample collections began on October 10, 2008 and will continue for the foreseeable future. The results of the groundwater quality data are reported in Appendix 2.04.7- 1 of this application along with the hydrographs from the nine monitoring holes. The water quality data from the 9 new monitoring holes supplements the water quality data reported in the New Horizon 1 permit documents. Ground water monitoring holes GW -N8 and GW -N9, installed by Peabody for the old Nucla Mine, are within the NHN permit area. Several other monitoring holes, GW -N3, GW -N4 and GW -N4R, are in close proximity to the NHN permit area and provide additional water quality information. NHN permit area is isolated from any potential impacts from the adjacent New Horizon Mine as a result of stream incision of the three stratigraphic zones (OB, Coal, and UB) by Tuttle Draw. Additionally, the old Peabody Nucla Mine is down dip and down drainage from NHN which essentially eliminates impacts to the NI-IN permit area from the old mine. From the work that has been done, it appears that another nest of 3 monitoring holes is warranted. This site would monitor the three bed rock zones (OB, Coal, and UB). The test site would be located in the southwestern-most part of the permit area and would be located immediately down gradient from the limit of mining disturbance. WFC will consult with CDRMS on location of additional nest site. This new site would be constructed after permit approval and prior to new disturbance. It is anticipated that this new nested test site would become the points of compliance for the three strata (OB, Coal, and UB). Section 2.04.7 Page 7 November 2011