2016-08-25_REPORT - C2009087 - Laserfiche WebLink

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Peabody Sage Creek Mining, LLC Page 6 8/25/2016 • The Total Rec. Iron standard was exceeded in June of 2015. • The total Mercury standard was exceeded in April and September of 2015. • The Selenium standard was exceeded in March of 2015. It is unclear if the Mercury standard was actually exceeded. The Method Detection Limit (MDL) for Mercury is .2 ug/l and the stream standard is .01 ug/1. Given this, the MDL is higher than the standard. According to the AHR, there is a temporary modification (expired December 31, 2018) of the Selenium standard as "current conditions". Therefore, the excursion of the Selenium standard is not considered an exceedance. PSCM also claims that part of the high Selenium levels is due to water received from Scotchman's Gulch, which is in contact with the Lewis Shale which contribute to high Selenium values in many of the streams in the area. PSCM claims that the Iron excursion was a result of high suspended solids and noted that no excursions occurs at NPDES sites. However there was an exceedance of Iron observed in NPDES 003 in October of 2014, but there was not an exceedance in June of 2015 which is when there was an exceedance observed at site YSG5. According to the AHR, the detection limit for Ammonia is .05 mg/l and that all values above the detection limit are compared to the table standard on page 87 of the EPA website: http://nepis.epa.gov/Adobe/PDF/20003O3L.pdf Based on this table it does not appear the ammonia limit was exceeded given the temperature of the water and the pH at the time of sampling. Mercury exceedances: According to page 22 of the 2015 AHR, the Colorado Department of Public Health and Environment performed a reasonable potential analysis on PSCM's outfalls and determined that there was no reasonable potential for PSCM's outfalls to exceed the Mercury limit; therefore,