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pH <br />Chloride <br />Sulfate <br />Dissolved <br />Solids <br />Selenium <br />Thallium <br />6.5 -8.5 <br />2500 mg /L <br />2500 <br />mg /L <br />12,500 mg /L <br />501- 10,000mg /1 <br />background = <br />X 1.25 <br />0.10 mg/L <br />0.002 mg /L <br />CEMEX understands that the applicable standards will only apply to the monitoring wells, not <br />C -Pit itself In TR -10, it was accepted that there is little risk to wildlife from the open C -Pit <br />water given the reduction in pH, selenium and a significant decrease in the size of the water <br />body. CEMEX will continue to pump C -Pit water into the cooling tower as part of the cement <br />manufacturing process in order to mitigate the risk to wildlife by significantly reducing the water <br />volume in the pond throughout the year. <br />As a result at this time CEMEX also proposes the elimination of the streamers as <br />stated in the TR -10 around the C -Pit pond given the limited water surface area <br />and the lack of any noticeable wildlife use in the surrounding area. <br />Comment 2. The Operator has proposed reducing the sampling frequency of C -Pit and <br />monitoring location CEM -004 from quarterly to semi- annually. Selenium levels <br />in C -Pit water have continued to exceed the numeric protection level standards. <br />As such, the Division believes the sampling frequency of C -Pit and CEM -004 <br />should continue on a quarterly basis. If in the future, levels of Selenium in C -Pit <br />water are consistently below the numeric protection levels standards, then the <br />Division will consider reducing the sampling frequency through a subsequent <br />Technical Revision. <br />Response: CEMEX will continue to sample on a quarterly basis the analytes listed in our <br />response above. After applicable standards have been established CEMEX <br />proposes sampling for four quarters. If the numeric standards have not been <br />exceeded CEMEX proposes that the sampling frequency be reduced to semi- <br />annually. <br />Comment 3. The Operator has stated "If the monitoring determines that C -Pit water may be <br />impacting the St.Vrain alluvium, DRMS will be consulted to determine the <br />appropriate response." Rule 3.1.7(9) requires an Operator to provide the Division <br />with a written report within five working days when there is evidence of <br />groundwater discharges exceeding applicable groundwater standards. In the event <br />groundwater exceeds the applicable standards, the Division will work with the <br />Page 4 of 6 <br />