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Yoast Mine AHR 2019 <br /> Requirement Requirement citation Comment <br /> 8. Basic Standards for CWQCC regulations The manganese standard was exceeded at five sites. <br /> Surface Water 31.1.11 Based on CWQCC reg. 31,the standard of 0.2 mg/l, <br /> applies to plants grown in acidic soils (<6.0 pH). In <br /> alkaline soils, as found throughout the Yoast and <br /> Seneca IIW region, the EPA standard would be 10 <br /> mg/l. The maximum manganese value observed at any <br /> surface site was 0.98 mg/I. <br /> 9. Instream Numeric CWQCC regulation 33.0 Nine monitoring sites exist within the Sage and <br /> Standards Grassy Creek Basins: YSSF3,NPDES 12,NPDES 13, <br /> NPDES 14,and YSS2 are on Sage Creek. NPDES <br /> 10,NPDES 11,YSGF5, and YSG5 are on Grassy <br /> Creek. In addition, Spoil Springs YSSPG3, YSSPG4, <br /> and YSSPG5 are found within the Sage Creek Basin <br /> and Spoil Springs YSSPG 1 and YSSPG2 are found <br /> within the Grassy Creek/Annand Draw Basin. The <br /> receiving stream standard for both Sage Creek and <br /> Grassy Creek is on Segment 13e of the Yampa River <br /> basin. <br /> The stream standards for Sage Creek and Grassy <br /> Creek are based on aquatic life standards. Table 13 of <br /> the 2019 AHR provides a comparison of the standards <br /> to water quality collected from NPDES points and <br /> stream sites in the Sage and Grassy Creek Basins. <br /> The total recoverable iron standard (1.0 mg/1) was <br /> exceeded at the YSG5 site. <br /> A high level mercury test with a method detection <br /> limit of 0.2 ug/1 for streams and a low level mercury <br /> test with a method detection limit of 0.0002 ug/1 for <br /> NPDES sites was run. All high level test values this <br /> year were less than the detection limit. <br /> NPDES 013,NPDES 12,and NPDES 10 exceeded the <br /> selenium standard. The exceedances of the selenium <br /> stream standard were not NPDES permit limit <br /> exceedances. <br />