2016-12-01_PERMIT FILE - C1980007 (6)

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2016 Recommended Modifications to the West Elk Mine Hydrologic Monitoring Network 10 2.1.1.3 Spring G -28a (Decreed Spring #20) Spring G -28a is located in a north tributary to Gribble Gulch (Map 1). It is situated above Panel 7 in the Northwest B -Seam mine area. This spring issues from alluvium and is seasonal. Flow usually occurs during the peak flow period and accumulates in a stock pond. Spring G -28a has been monitored since 1978 and was undermined in July 1994. The spring flow measurements were highly variable from 1977 to 1998, but have been steady since October 1999. A time -series flow graph for this spring is shown on Figure 5. Figure 5. Flow in Spring G -28a Time -series water quality data from Spring G -28a do not indicate any adverse trends in water quality. The laboratory ECs for this spring for the period of record are steady, and range from 749 to 1,110 µmhos/cm and average about 990 µmhos/cm. In comparison, the single baseline laboratory EC value was 1,600 µmhos/cm. TDS values for this spring for the period of record also are also steady, ranging from 510 mg/L to 676 mg/L, and averaging about 617 mg/L, compared to a single baseline value of 1,100 mg/L. There are no baseline values for field pH for this site (WWE, 2001) for comparison; however, one laboratory pH value is available for comparison. The field pH values for this spring over the period of record are relatively steady, ranging from 7.10 to 8.39 s.u., and averaging about 7.40 s.u. In comparison, the baseline laboratory pH value was 7.9 s.u. TSS values for this spring for the period of record are variable, ranging from ND to 88 mg/L. Dissolved iron values are also variable, ranging from ND to 0.66 mg/L. Total iron values are variable, ranging from 0.09 to 0.63 mg/L, and averaging 0.50 mg/L, compared to the single baseline value of 1.12 mg/L. The time -series water quality graphs for Spring G -28a are shown in Figure 6. August 2016 HydroGeo, Inc.