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- 4-11 Five monitoring wells were installed in the alluvium of the East Salt Creek and its tributaries (Munger Creek and an un- named east branch) to monitor changes in groundwater eleva- tions and groundwater quality. The monitoring wells consist of 2z-inch PVC casing, perforated in the zones of interest. The perforated part was enveloped by gravel pack and a bento- nite pellet seal was placed on the top of the gravel pack. Data pertinent to monitoring wells installation are listed in Table 4.3-3S and typical construction of a monitoring well is shown on Figure 4.2-55. In all installed monitoring wells, a falling head type of field permeability test was performed. The results of testing were interpreted by the Hvorslev (1972) method and are listed in Table 4.3-35. Locations of monitor- ing wells are shown on Figure 4.2-25. During the groundwater investigation program, the site and adjacent areas were inspected for springs, seeps and other in- dications of groundwater presence. As was noted in the ori- ginal application, none were found. 4.2.2.1 Characteristics of Water Bearing Strata Potential water bearing strata at the site occur in alluvial sediments of the East Salt Creek and its tributaries, and in the bedrock. The bedrock aquifers are contained in sand- stone strata and locally in some coal seams. Alluvium Alluvial sediments of considerable depth have developed along the East Salt Creek. The boreholes in the East Salt Creek alluvium were drilled up to 85.5 feet. None of the bore- holes reached bedrock. As interpreted on Cross-Section A-A' (Figure 4.2-35) through the East Salt Creek Valley, it is poss- ible that the thickness of alluvial sediments reaches 130 feet. Alluvium is composed primarily of gravel-sand mixtures with a high content of fine-grained materials. As shown on Figure • 4.2-25, water table in the alluvium of East Salt Creek is 32 Revised: 6/8/84