Laserfiche WebLink
Page 6 December 19, 2013 <br />Member of the Green River Formation in his study of wells and springs in the vicinity of Logan Wash <br />(see Table 3 presented in the TR No. 8 application). Weeks and others (1974) reported boron <br />concentrations ranging from 260 to 120,000 µg/L in wells completed in the Lower Aquifer (lower <br />Parachute Creek Member) in the basin. The same report showed boron concentrations at Well No. 10 at <br />the C -B Oil Shale Tract to be over 300,000 µg/L and fluoride to range from 3.3 to 47 mg/L with an <br />average of 22.6 mg/L. Well No. 29 at the C -B Oil Shale Tract had boron concentrations of 5,500 pg/L <br />and fluoride concentrations of approximately 31 mg/L. <br />The groundwater of Well LWCW -IA is considered representative of groundwater underlying Dry <br />Gulch as the well is constructed within a few feet of the axis of the gulch. To assess whether <br />groundwater at Well LWCW -IA has been impacted by mine influences including discharge of LW- <br />001 mine water, WWL compared water chemistry for LW -001, LWCW -IA, and LW -22. <br />Table 6 shows the summary statistics for chemical constituents in Wells LW -001 and LWCW -IA, and <br />the analytical results for the only sample collected at Well LW -22. The data indicate the chemistry of <br />LW -001 mine water is of a distinguishably different composition than groundwater at LWCW -IA. For <br />example, alkalinity, boron, chromium, copper, iron, sodium, sulfate, total organic carbon (TOC) and <br />dissolved organic carbon (DOC) are among some of the constituents that have higher concentrations in <br />the LWCW -IA groundwater compared to the LW -001 mine water. <br />Examination of Table 2 shows that molybdenum concentrations in the leachate were virtually identical <br />to the mine water; molybdenum concentrations did not increase or decrease as a result of leaching of <br />the waste rock. The mine water to leachate ratios shown in Table 3 for boron, fluoride, and <br />molybdenum are near a value of 1, indicating small differences between mine water and leachate <br />concentrations. In many cases, the results for these constituents for the 001 mine water and the leachate <br />are within a common laboratory error of 20 percent. <br />Based on the above discussed data, the infiltrating mine water is not expected to negatively impact <br />concentrations of boron, fluoride or molybdenum in the ambient groundwater downgradient of the <br />lower dump. <br />7 Please commit to continue to conduct monthly chemical analysis ofLW -001 and LW -002 (discharge <br />occurs) and collecting semi - annual water samples from LWCW -IA for analysis of the extended <br />analytical suite. <br />Response: <br />OOSI is required to conduct monthly chemical analysis of LW-001 and LW -002 under the existing <br />CDPS permit with exception of the period from November through March of each calendar year <br />because of impracticable and unsafe access due to heavy snowpack conditions. <br />Upon approval of Technical Revision No. 8, and if required, OOSI will conduct sampling of the LW- <br />001 and LW -002 (if discharge occurs) mine water at a frequency agreed upon with DRMS. <br />OOSI has voluntarily collected water samples at Well LWCW -IA on a semi - annual basis for the last <br />three years and will continue to conduct this sampling and analysis program into the future. <br />Warsha11121713.doc <br />