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<br />~~ ~ ~~ December 1986 5 863-2052 <br />that angering was possible to a depth of 31.6 feet. In contrast, <br />cemented sandstone present in the vicinity of B-2 necessitated NX <br />coring from the ground surface in this boring. <br />Angering was not attempted when drilling B-4 because of the often <br />coarse, well-cemented nature of the spoil materials present. In- <br />stead, 4.5-inch OD temporary steel casing was advanced through <br />the mine spoil using a wireline-retrievable inner tricone bit in <br />connection with rotary wash techniques. As noted on Figure 8, <br />California or split-spoon samples were collected at various <br />depths when drilling through the spoil materials. Intact <br />Williams Fork units present beneath the mine spoil were YX cored <br />with water. Unfortunately, drill rod wobble when coring B-4 <br />resulted in relatively poor core recovery, as indicated on the <br />boring log. The corresponding RQD (rock quality designation) <br />values are unrealistically low due to the poor core recovery and <br />drilling-induced fracturing of the core. <br />2.2 Piezometer Installation/Monitori <br />Upon completion of each boring, nominal 1-inch diameter Schedule <br />80 PVC pipe was placed in each borehole to facilitate subsequent <br />piezometric monitoring. Machine-slotted PVC casing (0.010-inch <br />wide slots) and similar flush-joint riser pipe was placed as <br />shown on Figure 10 and the boring logs. Colorado Silica sand <br />(8-12 size) was then placed in the annular space to above the <br />slotted PVC. A minimum 2-foot thick bentonite pellet plug was <br />used to seal the annular space above each sand pack, and the <br />remaining annular space was backfilled with dri21 cuttings. <br />Piezometeric measurements (Table 1) through October 10, 1986 were <br />made by Golder using an electronic water-level probe. Subsequent <br />piezometric measurements were made by site personnel. In <br />Golder Associates <br />