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Ms. Christine Johnston Mountain Coal Company Page 2 August 23, 1996 All Colorado Discharge Permit System (CDPS) limitations were met for all discharge points for WY 1993. The CDPS limitation for TSS was exceeded in the second quarter of 1994 at discharge point 007A. From the data presented, it appears that all other discharge limitations were met for ~'/Y 1994. One potentially significant water quality effect is noted for the shallow groundwater in the vicinity of the lower refuse pile. From the laboratory analytical results summarized in Appendix E (1993 AHR) it appears that the lower refuse pile is the likely cause of the higher iron readings in alluvial groundwater adjacent to the pile. Iron concentrations detected in groundwater monitoring wells across the site during WY 1993 ranged from not detected to 69.2 mg/1. The highest concentration of 69.2 mg/I was detected in well GP-1 located on the east flank of the refuse pile. In addition pond MB-6 which treated surface water runoff from the refuse pile (during WY 1993) showed an elevated iron concentration of 121 mg/I on 09/07/93. The Sylvester Creek sample, well SG-1, and well SOM-13-H also showed comparatively high concentrations of iron during the spring of 1993. The 1994 sample data also show that iron concentrations are elevated above the range of baseline parameters for iron in wells SG-l and GP-1 both located down gradient of the lower refuse pile. Water quantity and quality data presented in the 1993 and 1994 AHRs will require some clarification as described below. The Division has the following specific comments regarding the 1993 and 1994 AHRs. Water Year 1993 1. For WY 1993 there were a total of eight surface water monitoring locations in the approved water quality monitoring program. Seven of the eight stations required continuous discharge measurements and all eight monitoring stations required water quality measurements three times per year. For clarification, USGS North Fork Gaging Station near Somerset is the same monitoring point as North Fork Upper. The spillway at Beaver Reservoir was not a required monitoring station. On page 2, the first paragraph under Surface Water Monitoring is confusing and should be rephrased to reflect the monitoring locations as presented in Table 1 of the AHR. Please provide a revised report page. 2. On page 3, the first paragraph states that nearly three months of data were not acquired due to sediment below the Flume in Sylvester Gulch. I[ is not clear how this interfered with sample collection. Please clarify how this