Laserfiche WebLink
RULE 2 PERMITS <br />Exploration Test Borings <br />Exploration test borings have been conducted within the Collom mining area and have been used for the <br />following purposes: <br />Identifying Location of Subsurface Water - Several drill holes throughout the area encountered minor <br />amounts of groundwater; however, all of the data obtained to date by Colowyo and the United States <br />Geological Survey (USGS) have indicated that groundwater occurrences in the Williams Fork Formation <br />in the area are not continuous but rather are a series of perched systems of limited lateral and vertical <br />extent. Information on groundwater occurrence is provided in section 2.04.7. <br />Characterizing Physical Properties of the Overburden - The overburden material, which is removed as <br />a part of the mining operation, consists mainly of mudstones, siltstones, and sandstones. Generally, the <br />mudstones will have a relatively high erodibility and compaction factor, while sandstones and siltstones <br />will have low erodibility factors and low to moderate compaction. Because of the variable lithology and <br />lenticular nature of the strata in the Collom permit expansion area and the variations in the mining <br />techniques, it is difficult to determine an actual value for the swell of the overburden; therefore, the <br />overall swell of the overburden material was estimated to be approximately 20 percent. Calculations for <br />verification of swell factors have been presented in the Colowyo Annual Reports. <br />Evaluating Geochemical Properties of Overburden - Chemical analyses of overburden and interburden <br />strata in the areas to be mined are provided in Exhibit 6, Item 9 (Geology Exhibit 3 Overburden <br />Chemistry). The ongoing overburden sampling program at Colowyo described in Exhibit 6, Item 4 of the <br />existing permit document (Volume 1) has confirmed earlier estimates of the geochemical properties of the <br />overburden identified by exploratory drilling. In addition, test results are compared with appropriate <br />overburden guidelines (Table 2.04.6 -5) to assess the acid - forming, toxic - forming, or alkalinity- producing <br />potential of overburden material within the Collom permit expansion area. A summary of overburden <br />geochemistry is presented in Table 2.04.6 -6 and the relevant borehole locations are shown on Map 11 B. <br />Logs of drill holes and test borings within the Collom project area can be found in Exhibit 6, Item 10 <br />(Geologic Data for Collom Cross Sections — Drill Hole Information). <br />This section presents the results and interpretations of geochemical tests performed on overburden <br />material samples from the Collom Lite pit area. The purpose of these tests is to determine the chemical <br />composition and assess the acid - forming, toxic - forming, or alkalinity- producing potential of overburden <br />material within the Collom permit expansion area. This section describes the methods used in collecting <br />overburden samples for testing, the types of tests performed and the tests results. <br />Overburden material will be excavated and stockpiled in a temporary out -of -pit disposal facility identified <br />on Map 23B as Out of Pit Spoil and Overburden Stockpile or used for backfilling and re- contouring the <br />pit. In addition, overburden materials around the perimeter of the mine blocks will be exposed but not <br />removed. Table 2.05.6 -5 presents a mine -wide volumetric calculation in support of the post mining <br />topography and illustrates that permanent out of pit spoil is not needed. <br />Colowyo drilled boreholes to obtain overburden and interburden samples for physiochemical analysis. <br />The locations of the boreholes relevant to this application are shown on Map 11 B. These boreholes are <br />C- 04 -04, C- 04 -14, C- 04 -25, C- 04 -36, C- 05 -26, and C- 05 -32. These drill holes are near or within the <br />footprint of the proposed Collom Lite pit. <br />The CDRMS Guidelines for the Collection of Baseline Dater Quality and Overburden Gwehemistry <br />recommends sampling one hole per square mile, with a minimum of three per permit area. The drill holes <br />Collom — Rule 2, Page 30 Revision Date: 9/28/11 <br />Revision No.: PR -03 <br />