Laserfiche WebLink
Cripple Creek & Victor Gold Mining Company Squaw Gulch Valley Leach Facility Design <br />solution application loss increases to 5 percent during early closure using wobblers or <br />other devices that increase evaporation. <br />In summary, the average amount of precipitation per year is 18.9 inches, and the <br />average amount of lake evaporation per year is 44.3 inches. <br />2.3 Geology <br />A description for the regional geology of the area is presented in reports by CC &V that <br />have been previously submitted to the OMLR in Amendment No. 5 and supporting <br />documentation (see the July 29, 1993, letter from CC &V to the OMLR titled, <br />"Amendment 5 to Permit #M- 1980 -244; Information Responding to Concerns of OMLR <br />Staff') and as recently as Amendment No. 9. This information is not reproduced in this <br />document; however, a summary is presented below. This information was compiled <br />by CC &V and presented to AMEC for use in this report. The information provided to <br />AMEC was confirmed during site reconnaissance. Drawing A40 presents a map of the <br />surficial geology in the project area. <br />Four rock types compose the general bedrock geology of the VLF area. The <br />predominant bedrock unit is the Cripple Creek Lapilli breccia (Tbx1I), which is <br />generally massive, structureless, matrix - supported breccia that is poorly sorted, typical <br />of diatremal crater fill breccia. Clasts are sub - angular to sub - rounded and primarily <br />composed of various phonolite units with occasional pre- Cambrian fragments. The <br />breccia commonly shows varying degrees of hydrothermal alteration. The second and <br />third rock types are the Plagioclase Phonolite (Tphk) and the Phonolite (Tph), <br />respectively. The Phonolite is light- to medium -gray, porphyry with subhedral to <br />euhedral, medium- to coarse - grained phenocrysts of alkali feldspar with minor <br />amounts of feldspathoids, glassy apatite, and pyroxenes. The fourth unit is Biotite <br />bearing plagioclase Phonolite (Tphb). This material is generally a gray, fine - grained <br />porphyry with euhedral biotite and alkali feldspar phenocrysts. <br />2.4 Underground Workings <br />Portions of the area beneath the proposed VLF were previously mined by underground <br />means. Underground mine development was generally undertaken from shafts and <br />occurred at various elevations. The underground working levels generally followed <br />veins that were typically less than 12 feet wide (cross - sectional dimension of drifts and <br />laterals). In some workings, open stope mining methods were used that followed ore <br />veins upward from the working level excavations. <br />Surface disturbances from caving of the underground workings are visually evident in <br />some areas within the VLF. These surface disturbances are primarily evident in the <br />central VLF area. In many areas, the underground excavations remain open. There is <br />no evidence that any of the excavations were ever backfilled with mine development <br />material, although some of the excavations were indicated on the historical mining <br />plans as having collapsed and caved. <br />Project No.: 74201125G0 Page 10 <br />1 September 2011 <br />amec <br />