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'~~~ xenar 6 A4sodaae*, Inc. GeataCtlnral and AAatmials Engrreers and Errriromitantar Scientists t. "'~~-'. November 7, 2006 Thompson Properties Go Norryuki 8 Parker, PC PO Box 949 Granby, Colorado 80446 Attn: Ms. Georgia Noriyuki 2390 South Lipan Street Denver, CO 80223 phone: (303) 742-9700 fez: (303J 742-9666 ACEC email: kadeover(a)~kumanrsa.wm u~ ein.e www.kumarusa com Other Office Locations: Colorado Springs, Fort Collms, Pueblo and Winter Park/Freacr, Colorado Subject: Geotechnical Engineering Study and Slope Stability Evaluation, Proposed Gravel Plt Expansion, Thompson Properties Gravel Pit, Granby, Colorado Project No. 06-i-556 Dear Ms. Noriyuki: This letter presents the results of a geotechnical engineering study pertormed to evaluate the stability of permanent cut slopes for a proposed expansion of the Thompson Gravel Pft, located in Granby, Colorado. The study was performed in accordance with the scope of work presented in our Proposal No. P-O6-610 dated October 10, 2008, and our Proposal No. P-06-628 dated oaober is, 200x. Project Descpgtion: Thompson Properties proposes to expand the Thompson Gravel Pit mining operations by extending the pit to the east within the boundades shown on Fig. 1. The east cut slope of the pit currently being mined is approximately 40 feet deep, and the proposed expansion pit will be mined to a similar depth. Thompson Properties has submitted plans and dowments to Grand County to obtain a spedal use permit for mining, and a Redamation Pian that indudes grading bade the final cut slopes of the expansion bade toe 2:1 (hodzontal:verfical) slope is inducted as part of that submittal. The Colorado Geologic Survey {CGS) has reviewed the submittal for the County, and has requested that a qualified geotechnical engineer evaluate the stabiNty of the proposed permanent cut sbpes and permanent setbacks from the top of the excavated slope to the properly beundaries. t~olooic and Site Conditions: The project site is located in the Southern Rocky Mountains physiographic province in an area characterized by glacial moraines and glacial outwash deposits, which overlie Miocene-age Troublesome Formation siltstones and mudstones, and Cretaceous-age shale, siltstone and sandstone ('Geologic Map of the Granby Quadrangle, Grand County, Colorado, by D.A. Schroeder, 1995). Based on observations from a geologic site reconnaissance performed on October 13, 2006, the existing gravel pit and exposed expansion is located on an alluvial terrace deposit on the north side of the Fraser River. Material observed in the excavated cut slopes of the pit generally mnsisted of subrounded to rounded, poorly graded gravel with sand. The upper Z to 3 feet of the cut slope on the east side of the existing pit generally consisted of wind-blown sik or loess, and the upper 4 to 8 feet of material observed in the cut slope on the south end of the pit generally mnsisted of Slightly cemented, silty to clayey gravel and sand. The indination of the exravated pit slopes ranged from about 1.5:1 (horizontal:vertical) near the base of the slope, to anear-vertical inclination at