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<br />Hydrogeological Sector III <br />In Sector III, a similar relationship exists between the major strata and <br />the Gordon Arroyo alluvium. Piezometric levels at Sites W82-2, W82-3 and W82-15 <br />are largely hydrostatic. Ground water flow proceeds up dip from the west, moving <br />through the strata and ultimately discharging to the alluvium of the Gordon. The <br />point at which these strata subcrop beneath the alluvium is where discharge takes <br />place. <br />Geochemical data confirms this flow system. The electrical <br />conductivity (EC) of the Alluvial Well in Gordon Arroyo, located up gradient of the <br />Cameron and Lennox seam subcrop is 900 u mho/em. In contrast, alluvial <br />piezometers down gradient from the subcrop limit have higher EC values. This <br />increase in EC is indicative of mine waters discharging to the alluvium. The <br />Gordon Mine workings intersect the Gordon Arroyo alluvium just upstream from <br />• W82-21A. The intersection controls the interaction of the alluvial ground water <br />discharge with the workings and bedrock ground water discharge. <br />Ground Water Quality <br />Limited chemistry sampling of "natural" ground waters in the region has <br />been conducted as most ground waters in the area have been affected by historic <br />mining activities. The major chemistry of "natural" ground water in the mine plan <br />region is dominated by sodium and bicarbonate species. Concentrations generally <br />range from 70 to 200 mg/1 for sodium, and from 150 to 350 mg/1 for bicarbonate. <br />Calcium and sulfate are also present in significant quantities. Calcium values <br />range between approximately 50 and 100 mg/1 while sulfate ranges between 200 <br />and 350 mg/l, rivaling bicarbonate as the dominant ion. Total dissolved solids <br />(TDS) values vary between 800 and 1300 mg/l, and average approximately <br />1000 mg/1. pH values are neutral to alkaline, varying from 6.5 to 8.2. <br /> <br />-10- <br />