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February 1998 H~G Coal 1997Annrral Reclamation Report ~ PaRe 7 <br />. 4.2 GROUNDWATER <br />HGCC performed semi-annual groundwater monitoring at three ground water monitoring <br />wells, HG-1, HG-2 and UC-2 as specified in the existing, valid Permit. <br />Well HGl monitors ground water quality and water level down dip of the reclaimed shop <br />area. Results of water-quality samples colletted during 1997 indicate all water quality <br />pazameters are within previously observed ranges, except for total suspended solids (TSS), and <br />total aluminum, total iron and total manganese. TSS concentrations were 940 milligrams per <br />liter (mg/1) and 904 mg/1 in the June and October samples, respectively. Total aluminum <br />values were 19.3 mg/1 and 9.34 mg/1, total iron concentrations were 34.2 mg/1 and 19.0 mg/l <br />and total manganese values were 0.63 mg/1 and 0.47 mg/l. Well HG-2 is used to monitor <br />ground water quality and water level down dip of the reclaimed mine area. Results of water- <br />qualiry samples collected during 1997 indicate all water quality pazamecers aze within <br />previously observed ranges, except for TSS and [oral manganese. TSS concentrations were 204 <br />mg/1 and 610 mg/1 in the June and October samples, respectively and the total manganese value <br />in October was 2.44 mg/1. The cause of the increased TSS and total metals in both wells is <br />probably related to a change in the sampling method during the fall of 1996. Prior to fall 1996, <br />a submersible pump was used to evacuate the wells and collect the ground water samples. <br />During fall 1996, HGCC ins[alled a positive~isplacement type pump system in the wells. The <br />repetitive up-and-down motion of the pump tubing could be agitating any sediments in the <br />bottom of the well, increasing the mass of sediment suspended in the water column. In <br />addition, the pump tubing knocks against the side of the well casing and the knocking motion <br />• could introduce additional suspended solids into the well water column. The increase in total <br />metal concentrattons is probably related to the increase in TSS concentrattons. Sediments often <br />are associated with oxyhydroxides of these metals. It is important to note that there was no <br />observed increase in any ground water dissolved concentrations or surface water TSS or metals <br />concentrations. <br />Monitoring well UC-2 is only monitored for water levels. The data indicates no significant <br />changes in water elevations occurred during 1997. <br />Groundwater monitoring data is also included in Exhibit 4. <br />4.3 RESPONSES TO DMG COMMENTS ON THE 1996 ANNUAL HYDROLOGY <br />REPORT <br />In a letter dated Ottober 15, 1997, DMG presented HGCC with comments on the 1996 <br />Annual Hydrology Report. In the letter, DMG indicated that the 1996 report fulfilled the 1996 <br />reporting requirements of Rule 4.05.13(4)(c) with two exceptions. Presented below are those <br />two exceptions and HGCC responses. <br />1. Water levels in well UC•2 were not reported as required in Section 2.05.6(3J(bJ(iiiJ, Volume <br />18 of the permit application (this is the only measurement required in this wellJ. Please <br />explain the reason for not reporting the water level in UC2. <br />• <br />Montgomery Watson Americas, lnc. (dba TerraMatrizJ <br />p.0. Box 774018 Steamboat Springs, CO 80477 "(970J 879-6260 <br />..~e~nn,..eepv~n~xq <br />/r]Nar <br />