|
• As can be seen by the water chemistry data presented in Appendix 7-4, the water quality of
<br />the Hubberson Gulch alluvium is poorer than that of the Watering Trough Gulch alluvium.
<br />This difference in water quality is probably determined by proximity to coal outcrops.
<br />The Hubberson Gulch alluvial system drains an area that is closer to Wadqe and Wolf Creek
<br />coal outcrops (Exhibit 7-1). The relationship between water quality and location is
<br />especially evident at GW-52W-19A which, of all the alluvial wells, has the most eastern
<br />location (i.e., closest to the coal outcrops) and the poorest quality water.
<br />Wadge Overburden Aquifer. Water chemistry monitoring of the Wadge Overburden aquifer has
<br />been conducted at five wells: GW-52W-20V, -140V, -150V, -170V, and -180V. Water quality
<br />monitoring at CW-52W-20V was discontinued after 1985. As discussed in the "Ground Water
<br />Levels" section of Tab 7, ground water levels for Well CW-52W-20V after 1981 are
<br />considered suspect. However, careful examination of water quality data for this site
<br />after 1981 indicates that they are representative when compared with earlier data, so they
<br />are used in the analyses below. Although Well CW-52W-160V is on the water quality
<br />monitoring schedule, it has never produced sufficient water for sampling.
<br />• As can be seen in Table 7-14, the Overburden aquifer contains waters that are either
<br /> strongly bicarbonate or sulfate water types. Like the Hubb erson Gulch alluvium, water
<br /> type in the Overburden appears to be controlled by location; Wells GW-52W-20V and -180V,
<br /> located in the southern part of the permit area (see Exhibit 7-1), have PIgCaNa+K-HC0
<br />and
<br /> 3
<br /> MgNa+KCa-HC0
<br />water types, whi le Wells GW-S2W-140V, -150V, and -170V, located to the
<br /> 3
<br /> north, have CaMg-50
<br />, Na+K-50
<br />, and MgNa+KCa-50 water types, respectively.
<br /> 4
<br />4 4
<br />Overburden water is approximately neutral, with an average pH of 7.09 and a range of pH
<br />values from 6.68 to 7.80 (Table 7-15 ). The Overburden aquifer has an average TDS of
<br />2,582 mg/1, but this parameter varies considerably with a range of 600 to 8,586 mg/1. As
<br />with water type, TDS concentrations appear to be controlled 6y location; Wells GW-52W-20V
<br />and -180V have much lower TDS values than the wells located to the north. Also, as
<br />expected, sulfate concentrations are much higher at the more northern wells,
<br />Detectable concentrations of A1, As, B, Cd, Cr, F, Fe, Pb, Mn, Mo, Ni, and Zn have been
<br />measured in the Overburden aquifer, All concentrations were less than 1.0 mg/1, with the
<br />exception of B, F, Fe, Mn, and Zn.
<br />•
<br />Although some water chemistry variability is evident at some sites (e.g., 504 and TDS
<br />45
<br />
|