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Addendum to Geotechnical Data Report <br />Bowie Resources, Limited <br />July 2002 <br />Executive Summa <br />The purpose of this Addendum Report is to present additional geotechnical information that <br />was collected after the Geotechnical Data Report, Bruce Park Dam, Delta County, Colorado <br />was issued in April 2001 (GEI, 2001). Analyses and interpretations of the information <br />collected will be provided in a separate document. <br />GEI performed the following scope of work for this project: a) developed and observed <br />completion of a subsurface investigation program, which included soil and bedrock borings, <br />field testing, and installation of open-standpipe piezometers and cable. inclinometers; b) <br />performed laboratory tests on selected soil samples collected during the subsurface <br />investigations; and c) prepared this Addendum Geotechnical Data Report. <br />Glacial materials were encountered initially or below topsoil in the borings drilled in the <br />existing landslide area and extend to depths from 6.7 to 24.5 feet. The glacial materials are <br />generally low to medium plastic clays with 15 to 75 percent sand, 5 to 30 percent gravel, and <br />classify as CL according to the Unified Soil Classification System (USCS). A possible <br />• failure zone less than 1 foot thick was identified in Boring BL-102 within the glacial <br />deposits, at a depth of 19.5 feet. This material consists of soft, moist to very moist, low to <br />medium plastic clays that visually classify as CL according to the USCS. <br />Bedrock was encountered below the glacial materials. The bedrock generally consists of <br />interbedded claystone and sandstone of the Mesa Verde Group. <br />Groundwater was not encountered in any of the borings at the time of drilling below the <br />landslide, drilling fluid was lost in BL-102 at about 19.5 feet in depth. <br />In general, the main dam embankment and foundation consist of four material types <br />identified as new embankment, old embankment, foundation soils, and bedrock as described <br />in Geotechnical Data Report (GEI, 2001). <br />In Boring BD-104, new embankment material was identified from ground surface to 8.5 feet, <br />old embankment materials from 8.5 feet to 12 feet, foundation soils (glacial deposits) from <br />12 feet to 18.5 feet, and bedrock from 18.5 feet to 23.5 feet. A few small roots and other <br />organic material were identified in the old embankment material. However, an organic layer <br />was not identified. <br />Groundwater was not encountered in Boring BD-104 during drilling. <br />III 99292 02-07-03 Addendum Geotechni <br />GEI Consultants, Inc.