2017-07-11_REVISION - C1981010 - Laserfiche WebLink

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5 5 Trapper Mine PR8 Preliminary Adequacy Review Prepared by: R. Reilley July 2017 some ground water is exposed. Larger flows in Deacon Gulch are limited to springtime melts and precipitation events in the lower reaches outside of the permit boundary. Jeffway Gulch is dry for the majority of the length within the PR-7 permit boundary (as also shown in the added Table 2.7-12c, page 2-414m and added Figure 2.7-15f, page 2-414n). As described in replacement page 2-1411, at the southern edge of the expansion area a large unnamed tributary to Jeffway Gulch joins the main channel. A series of seeps are present within the PR-7 expansion area, as is intermittent flows from a large seep complex within the tributary from the east. The area becomes very wet at this junction and a defined channel leaves the expansion area at County Road 33. This riparian area is not expected to be disturbed as it is beyond the extent of the coal reserves in this area. The seeps appear to originate from the base of the Twenty Mile Sandstone and shale layers below the sandstone. TMI has sampled Jeffway Gulch at the location of the seeps at the southern edge of the permit area at a site labeled as Jeffway Spring@ County Road 33. Replacement page 2-451s has been updated to reflect the addition of water quality sampling. Figure 2.7-15f, page 2-414n, shows the visual flow observations for Deacon Gulch and Jeffway Gulch and the water quality sampling for Jeffway Gulch. Water quality results are shown on Table 2.7-18b, pages 2-451 v through 2-451 x. The water quality shows the dominant cations as magnesium and calcium, and the dominant anions as sulfate and bicarbonate. The samples can generally be characterized as magnesium- calcium-sulfate- bicarbonate type waters. Little variance is seen in the water quality over the time period of sampling. The pH is slightly alkaline at 8.0 to 8.2. All water quality values are below the primary drinking water standards and the surface water quality standards for the lower Yampa River (Colorado Water Quality Control Commission Regulation #37, Stream Classifications and Water Quality Standards for the Lower Yampa/Green River. July 2017 DRMS This section of the stipulation is adequately addressed. DRMS notes that the riparian area is not expected to be disturbed and that the Jeffway Spring system at County Road 33 will continue to be monitored. May 2017 Trapper e) Soil resource information required by Rule 2.04.9 for those portions of the permit area to be disturbed by surface operations and facilities. An Order I soil survey was performed on the expanded 795.71 acres in the PR-7 permit expansion area in 2014 to satisfy the permit baseline soils sampling requirements of the DRMS regulations. The 2014 survey identified soil mapping units based on the 2004 Soil Survey of Moffat County Area, Colorado published by the Natural Resources Conservation Service (NRCS). Previous surveys of the Trapper permit area were performed in 1972, 1979, and 1980. In 1986 the soil surveys were updated to conform to the U.S. Department of Agriculture (USDA) Moffat County soil survey in effect at that time. The earlier soil surveys used older mapping soil series numbers and nomenclature as recognized in the 1986 letter from Darrell Schroeder in Section 2.6.1.1 of the Trapper Mine permit document. Many of these older soil series could not be matched to the newer USDA soil series groups and mapping units or to the later 2004 NRCS Soil Survey of Moffat County. The original soil series descriptions from the 1972 and 1980 surveys are included in Section 2.6.1.1 to retain all relevant data from the original permit. The PR-7 area soils descriptions, based on the 2004 NRCS Soil Survey of Moffat County, have been placed in a new Section 2.6.3 of the permit document. All soils mapped and nomenclature in the 2014 survey and future surveys will align with updated soil series descriptions provided by NRCS and the Soil