Laserfiche WebLink
concentrations were at, or slightly below the agriculture use numeric <br />standard, manganese concentrations exceeded the agriculture use numeric <br />standard, and TDS concentrations were characteristic of a groundwater of <br />"limited use and quality." Data collected at HGDAL3 since 1998 do not show <br />any increasing trends. Concentrations fluctuate seasonally, but the values <br />have been within the historic ranges (see Annual Hydrology Reports for select <br />concentration Homographs). <br />Surface water data collected by PHCI in 1997 and 1998 support the alluvial <br />groundwater TDS loading demonstrated above. The TDS concentrations at <br />HGDALI, which is adjacent to monitor wells DCAL-3A/B were 1,150 and 3,830 <br />mg/1. A surface water site on lower Stokes Gulch (LOSTOK), adjacent to <br />monitor well SGAL-3, had TDS concentrations of 10,300 and 6,860 mg/1, while <br />an un-named tributary that collects runoff from the area to the southeast of <br />the Loadout (EDRYCK) and flows into Dry Creek just upstream of the Rail Loop <br />Culvert RRC-19A/B/C (see Exhibit 12-2) had TDS concentrations of 11,200 and <br />8,710 mg/1. Table 2 also includes select constituent data from these three <br />surface water locations. <br />• A particular concern identified by the CDMG in their January 18, 2005 letter, <br />is that coal leachate could potentially add dissolved chemical loads to the <br />Dry Creek alluvial aquifer. HGTI addressed a similar CDMG concern in a <br />memorandum addressed to Ms. Janet Binns dated February 2, 1994. The <br />memorandum presented a water quality evaluation prepared by HGTI in response <br />to Stipulation 3 and a CDMG letter dated June 25, 1993. Data included in the <br />memorandum were results of a column leach tests performed in December 1993 on <br />coal stockpile samples using Method 1312. Test results are presented in <br />Attachment 15-2 of the permit. Four leachate testa were performed, one with <br />"new" coal, two with "old" coal and one without coal to establish control <br />levels. Twenty-five constituents were analyzed, including those with water <br />quality standards. Tests o£ the "new" and "old" coal samples produced <br />similar results. Boron, in the "new" coal sample (0.85 mg/1), was the only <br />constituent that exceeded its respective agriculture use standard (0.75 <br />mg/1). HGTI noted in the 1994 memorandum that both stream and alluvial <br />background levels were similar to the leachate boron level. For sulfate and <br />total dissolved solids, both the stream and alluvial concentrations were <br />significantly higher (6 to 53 times higher) then the leachate results. The <br />1994 memorandum included a calculation that demonstrated the coal leachate <br />will have no impact on Dry Creek alluvial aquifer chemistry. <br />TR-06 7-2.9 Revised OS/OS <br />