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2016-01-07_PERMIT FILE - C2010089A (3)
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2016-01-07_PERMIT FILE - C2010089A (3)
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Last modified
1/30/2017 8:41:47 AM
Creation date
2/11/2016 9:52:31 AM
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DRMS Permit Index
Permit No
C2010089A
IBM Index Class Name
PERMIT FILE
Doc Date
1/7/2016
Doc Name
Hydrology Description
Section_Exhibit Name
Section 2.04.7
Media Type
D
Archive
Yes
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Aquifer Characteristics of the New Horizon North Mining Area Previous aquifer testing of <br />the Dakota Formation coal strata in the NHN area indicates that the overburden, coal and <br />underburden zone transmissivity and hydraulic conductivity values in the NHN area are low to <br />very low (see Tables 7-5 and 7-6 in Appendix 2.04.7-2 of this application). The overburden and <br />underburden aquifers have the higher values and the coal aquifer has the lowest transmissive <br />properties. There is approximately one order of magnitude range in the transmissivity and <br />hydraulic conductivity values for the overburden, coal and underburden aquifers. This suggests <br />that there is a high degree of spatial variability within the aquifers. Storage coefficients for the <br />various stratigraphic zones vary from about 10-4 to10-5 for the overburden and the <br />coal/underburden zones, respectively. Transmissivities (T) for overburden vary from a low of <br />about 13 ft2/day to a high of about 58 ft2/day at GW -N9 (located within the NHN permit area). T <br />values for the coal zone vary from 2.4 to 6.0 ft2/day and the T values for underburden vary from <br />about 3 to 88 ft2/day. The backfill monitoring well (GW -N27) was completed in the fall of 1987. <br />A short term specific capacity and transmissivity test was conducted at the time of water quality <br />sampling at Well GW -N27. A K -value (hydraulic conductivity) of 40 ft/day and a transmissivity <br />value of 261 ft2/day was determined (see Table 7-5 in Appendix 2.04.7 of this application) <br />indicating that the transmissivity in the back fill at this location is 4 to 5 times higher than that of <br />the overburden. The saturated thickness of backfill at this location is about 6.5 feet (see hydrograph <br />for well GW -N27 in Appendix 2.04.7-1 of this application). The aquifer characteristics (production <br />potential) of the three stratigraphic zones indicate that they are marginal at best for domestic use <br />and totally inadequate as a source for irrigation water. <br />Baseline Ground Water Ouality <br />Prior to drilling the nine ground water monitoring wells (see Map 2.04.7-1 for locations of <br />monitoring wells GW -N47 through GW -N55) the planned well locations, completion techniques, <br />water quality sampling schedules and the water quality sample parameters were discussed with <br />CDRMS for their input and guidance. Samples for groundwater quality analysis were collected <br />on a quarterly basis from eight of the nine wells; however, monitoring well GW -N55 has been <br />nearly dry to the point that collecting samples from that well is not possible. Water quality <br />sample collections began on October 10, 2008 and will continue for the foreseeable future. The <br />results of the groundwater quality data are reported in Appendix 2.04.7-1 of this application <br />along with the hydrographs from the nine monitoring wells. The water quality data from the 9 <br />new monitoring wells supplements the water quality data reported in the New Horizon 1 permit <br />documents. Ground water monitoring wells GW -N8 and GW -N9, installed by Peabody for the <br />old Nucla Mine, are within the NHN permit area. Several other monitoring wells, GW -N3, GW - <br />N4 and GW-N4R are in close proximity to the NHN permit area and provide additional water <br />quality information. NHN permit area is isolated from any potential impacts from the adjacent <br />New Horizon Mine as a result of stream incision of the three stratigraphic zones (OB, Coal and <br />UB) by Tuttle Draw. Additionally, the old Peabody Nucla Mine is down dip and down drainage <br />from NHN which essentially eliminates impacts to the NHN permit area from the old mine. <br />Section 2.04.7 Page 8 Sept. 2015 (TR -11) <br />
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