Laserfiche WebLink
The proposed site is currently occupied by an orchard. Other than fruit trees, the site is vegetated <br />with native grasses and shrubs. The existing ground surface slopes approximately 10% down to <br />the southeast. Small watercourses traverse the footprint. It is assumed that these watercourses <br />will be diverted around the gob pile prior to construction. The Fire Mountain Canal was not <br />flowing at the time of our investigation. The canal appears to have been lined with concrete. <br />However, much of the concrete has cracked and appears moderately to completely deteriorated <br />in places. <br />According to Dunrud (1989), geology of the proposed Gob Pile No. 3 site consists of <br />undifferentiated Quaternary alluvium and colluvium (Qac) on the north side of the site, grading <br />to Quatternary alluvium (Qa) on the southern portion of the site. Thickness of these surficial <br />deposits is uncertain, but likely varies from 50 to 100 feet thick, or more. Bedrock in the area <br />consists of nearly flat Cretaceous sedimentary bedrock units. Mancos Shale is mapped near the <br />bottom of the valley slope with the Mesaverde Formation overlying the Mancos Shale. Outcrops <br />of the Rollins Sandstone member of the Mesaverde Formation can be observed above the <br />existing Gob Pile No. 2. Subsurface conditions encountered during our geotechnical <br />investigation are discussed in Section 3.1. <br />3.0 SUBSURFACE CONDITIONS <br />A geotechnical site investigation was conducted by BGI in December 2006. A total of seven <br />• boreholes were drilled at the proposed Gob Pile No. 3 footprint to characterize the foundation <br />conditions. The boreholes, designated BG06-Ol through BG06-07, were surveyed after drilling. <br />Locations of these boreholes are presented on Drawing No. 2. Three additional boreholes, <br />designated BG06-10 through BG06-12, were drilled in December 2006 at the existing Gob Pile <br />No. 2. These boreholes were drilled within placed gob in order to obtain samples for strength <br />testing. Subsurface conditions encountered during drilling at Gob Pile No. 3 and Gob Pile No. 2, <br />are discussed below. Borehole logs are presented in Appendix A. <br />3.1 Gob Pile No. 3 <br />Locations of the majority of the boreholes were surveyed. Locations for boreholes drilled at the <br />Gob Pile No. 3 footprint are summarized in Table 1. <br />Table 1. Summary of Borehole Locations <br /> Elevation <br />Borehole ID Northing Easting (ft) <br />BG06-01 17675.345 35900. 930 5890.7 <br />BG06-02 18200.211 35900. 292 5927.0 <br />BG06-03 17944.483 35708. 487 5915.0 <br />BG06-04 18125.920 36542. 655 5902.9 <br />BG06-05 17848.679 36345. 276 5866.8 <br />BG06-06 17799.447 36081. 238 5895.1 <br />BG06-07 17547.199 35697. 084 5901.1 <br />• <br />Bowie Gob Pile No. 3 stability report <br />Project ri06-48I-002 <br />Page 5 of 17 <br />