2011-08-09_REVISION - C1981019 (9)

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• • • NH oxalate • Crush and Pulverize • AB -DTPA extraction • Hot water extraction • Saturated Paste Extraction • Water extraction Exploration Test Boring Results Summary ASA No. 9, Part 2 1965 M 74.2 USDA No. 1, 1972 ASA No. 9, Part 2, 1982 M3 -5.2 ASA No. 9, Part 2 1965 M 80 -3 USDA Handbook 66, M@ ASA No.9 M10 -2.3.2 RULE 2 PERMITS The physicochemical data from overburden sampling by Colowyo are provided for each interval sampled in Exhibit 6, Item 9. The overburden suitability criteria used in this analysis are shown in Table 2.04.6 -5. These criteria were generated by Wyoming Department of Environmental Quality, Land Quality Division (WDEQ -LQD) and are used for comparison purposes in this permit revision based on previous negotiations with the CDRMS. The WDEQ -LQD guidelines were used since Colorado has no published standards as of the date this permit was revised. The criteria can be found on the WDEQ -LQD web site under Guideline No. 1, Topsoil and Overburden, Table I -4 (August, 1994). A summary of borehole overburden and interburden results compared to the WDEQ criteria is provided in Table 2.04.6 -6, and a summary of the percentage of each borehole that is less than "suitable" for each selected WDEQ criterion is shown on Table 2.04.6 -7. These comparisons are for informational purposes only, since the criteria in Section 2.05.3(6) will determine regraded overburden success in the Collom mining areas. In general, shallow overburden and interburden (less than 200 feet below ground surface (bgs)) was found to not contain unsuitable constituents. Isolated occurrences of marginal quality constituent levels were detected at less than 200 feet in depth. Boreholes that contained constituents in the marginal to unsuitable range at shallow depths included: pH was detected at marginal levels in boreholes C -04 -25 (10 to 21 feet bgs), C -05 -26 (125 to 131 feet bgs); sodium adsorption ratio was detected at marginal levels in C -04 -14 (148 to 180 feet bgs); selenium was detected at a concentration at or slightly exceeding the suitability criteria in five of the borings; however, the occurrences were relatively isolated, ten feet in thickness or less and the criteria exceedances were at or slightly over the criteria concentration of 0.3 parts per million. The acid base potential was suitable in all borings above the 400 feet bgs depth. Arsenic was found at unsuitable concentrations for root zone placement in boring C -04 -25 below 379 feet bgs. The anticipated root and aquifer zones within the regraded overburden of the Collom permit expansion area should be of suitable quality due to the following: • There is a limited amount of unsuitable overburden material when compared to the amount of suitable overburden material within the Collom Lite pit area. • In general, the limited amount of overburden material that is unsuitable will be mixed with suitable material to create suitable root zone and aquifer restoration material during mining and the backfilling of pits and out -of -pit disposal facilities. • Unsuitable overburden materials that represent a considerable portion of the overburden to be mined will be identified, selectively handled, and isolated from aquifer and root zone areas within the backfilled pits and out -of -pit disposal facilities using the methods. Collom — Rule 2, Page 32 Revision Date: 8/5/11 Revision No.: PR -03