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1, <br />fault system underlying the dump, specifically how faults act as capillary barriers in the <br />unsaturated zone. <br />Since the report of the modeling was submitted, Cotter has investigated the abandoned <br />mine, the Black Diamond, located beneath the northern edge of the JD-8 Mine waste rock <br />pile. This mine is in the same stratigraphic horizon as the JD-8 but in the down-dropped <br />fault block relative to the JD-8 Mine. The workings of that mine aze nearly 200 feet <br />below the base of the JD-8 waste rock dump and terminate at, or very neaz the fault. The <br />mine is completely dry. Cross-section A-A' shows the relationship of the waste rock <br />dump to the fault and the lower mine workings. A few minor faults with displacement of <br />a few inches to two feet exist in the hanging wall of the main fault. All are dry. <br />The results of the modeling suggest that it could take up to 1,000 yeazs for water to travel <br />from the waste dump to the water table, if it is 400 feet below. Therefore, rather than a <br />monitor well in the aquifer, Cotter proposes a soil water sampler (lysimeter) be installed. <br />It will be neaz, and on the down-gradient side of the waste rock dump, while still <br />allowing for dump expansion. The approximate location of the proposed lysimeter was <br />discussed with DMG during the field meeting, and is shown on the attached map. This <br />will serve as a timely sampling system showing the amount and quality of water <br />percolating through the dump material. <br />The installation plans for the lysimeter aze as shown on the attached "OPERATING <br />INSTRUCTIONS FOR SOILMOISTURE EQUIPMENT CORPORATION MODEL <br />1920 F1 PRESSURE-VACUUM SOIL WATER SAMPLERS. <br />The monitoring schedule for the lysimeter installation will be to sample on a monthly <br />basis as long as adequate sample quantities can be collected, to establish a baseline set of <br />data. Following the initial collection efforts sampling may be reduced to a quarterly basis <br />depending on the concentrations of the potential contaminants in the samples. <br />Also included with this information is a report from GeoScience Services titled "The role <br />of fractures in unsaturated transport". This report discusses how the faults and fractures <br />in the azea of the JD-8 mine waste dump should limit the transportation of potential <br />contaminants from the mine waste material. <br />If you have further questions regarding these issues, please call Glen Williams, Manager, <br />at Cotter's Nucla office, 970-864-7347. <br />Respectfully, <br />Dick White, Project Geologist <br />Cotter Corporation <br />~~ ~~GQ~,1 <br />JD-8 geo_lsup - 2 - <br />