2017-08-24_REPORT - C2009087 - Laserfiche WebLink

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Page 10 Requirement Regulation Comment 20. Prevention of adverse impacts to ground water systems outside permit area CDRMS regulation 4.05.11(1) A groundwater point of compliance is not established for bedrock aquifers at this site. Compliance with the Basic Standards for ground water, as discussed in Item 10 above, indicates the permittee is likely preventing adverse impacts to ground water quality outside the permit area. All alluvial wells showed seasonal water level fluctuations in response to periods of precipitation or lack thereof. Overburden and coal well water are fluctuating in response to the precipitation recharge, induced ground water flow to the reclaimed mine pits, and in some cases, changes in reservoir water levels. Spoil well water levels indicate that down slope highwall portions of the spoil exhibit significant amounts of saturation. 21. Prevention of impacts to ground water that adversely impact post-mining land use CDRMS regulation 4.05.11(2) Underground development at the PSCM began during the 2011 water year and stopped soon after and no development work or mining was conducted in the 2016 water year. Due to the premature mining process, prevention of impacts to groundwater cannot be determined as of the date of this review. 22. Minimize disturbance to hydrologic balance within and adjacent to the permit area CDRMS regulation 4.05.1(1) Exceedances of applicable water quality standards are discussed in the preceding review items. Please see above for details. For surface water, no exceedances of the effluent limitations were reported for the 2016 water year. For groundwater, it has previously been determined that a bedrock groundwater point of compliance well is not necessary. The alluvial groundwater point of compliance well exceeded the selenium standard noted in Table 7 of the AHR. Other exceedances of the basic standards for ground water are discussed in section #18 of this review. Water levels at most wells are within their historic ranges with the one exception discussed in section #19 of this review. The mine is currently idle. No determination has been made concerning Item no. 7 mentioned above regarding elevated Selenium levels. An investigation by the CDPHE and Peabody Sage Creek Mining as to the cause of the elevated selenium measurements is ongoing. Should it be determined that these exceedances are due to impacts permitted under the current mine plan, revisions to the PHC may need to be required. 23. Prevention of material damage to the hydrologic balance outside the permit area CDRMS regulation 4.05.1(1) Surface water - Note Item No. 22 above Ground water – Note item 20, above.