2023-01-22_REPORT - C1994082 - Laserfiche WebLink

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Yoast Mine AHR 2021 Water Year 2020 October through 2021 September Requirement Requirement citation Comment 11. Basic Standards CWQCC regulations There were no exceedances of the agricultural use for Surface Water 31.1.11 surface water standards. Based on CWQCC reg. 31, the standard of 0.2 mg/l, applies to plants grown in acidic soils (<6.0 pH). In alkaline soils, as found throughout the Yoast and Seneca IIW region, the EPA standard would be 10 mg/l. 12. Instream CWQCC regulation 33.0 Nine monitoring sites exist within the Sage and Numeric Standards Grassy Creek Basins: YSSF3,NPDES 12,NPDES 13, NPDES14, and YSS2 are on Sage Creek. NPDES 10, NPDES 11,YSGF5,and YSG5 are on Grassy Creek. In addition, spoil springs YSSPG3, YSSPG4, and YSSPG5 are found within the Sage Creek Basin and spoil springs YSSPG 1 and YSSPG2 are found within the Grassy Creek/Annand Draw Basin. The receiving stream standard(aquatic life), for both Sage Creek and Grassy Creek are on segments 13c; 131 and 13j respectively of the Yampa River basin. There were two exceedances of the total recoverable iron standard in segment 13c and appear to result from natural erosional processes. The stream standards for Sage Creek and Grassy Creek are based on aquatic life standards. There were no exceedances of the aquatic life or Agricultural Use standards. The total recoverable iron standard (1.0 mg/1) was exceeded once each at the YSG5 and YSS2 sites. There was one exceedance in YSGF5 of the iron standard in the Grassy Creek segment and appears to be due to spring runoff. There was no exceedance in Sage Creek segments. There were no exceedances of the agricultural use standard A single exceedances of the selenium standard at NPDES 10,did not appear to constitute a NPDES permit limit exceedance. 13. Sampling frequency at Tab 15,Table 15-9 of The report indicates that all frequencies were met. surface water CDRMS mining permit Sampling frequency for NPDES sites is monthly for water C1994-082 quality, and Semi annually for surface water sites. 14. Parameters to be Tab 15,Table 15-4 and Parameters to be sampled are conductivity(umhos/cm), sampled at surface water 15-5 of CDRMS pH (units), temperature (C), total recoverable iron sites mining permit C-1994- (mg/I), dissolved manganese (mg/1), total mercury 082 (ug/1), dissolved nitrate (mg/1), dissolved nitrite (mg/I), total ammonia (mg/I), dissolved selenium (ug/1), dissolved sulfate (mg/1),total sulfide (mg/1),total suspended solids (mg/I) and total dissolved solids (mg/1). All required parameters were analyzed. All parameters were met. 3