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<br />c <br /> <br />. <br /> <br />. <br /> <br />- <br />. <br /> <br />chen and associates <br /> <br />CONSULTING GEOTECHNICAL ENGINEERS <br /> <br />96 SOUTH ZUNt STREET. OENVER. COlOAAOO 80223 . 3031144.1105 <br /> <br />. <br /> <br />" <br /> <br />May 18, 1984 <br /> <br />Subject: <br /> <br />Proposal for Geotechnical Evaluation, <br />Reservoir No. 15 Dam Rehabilitation, <br />Larimer County, Colorado. <br /> <br />Ms, Jackie L. Malcolm, P.E, <br />Bruns, Inc. <br />16 Mountain View Avenue <br />Lorqrront, Colorado 80501 <br /> <br />Deat: r1s, rlalcolm: <br /> <br />Chen & Associates, Inc. is pleased to present a proposal to conduct a <br />geotechnical evaluation for rehabilitation of the earthfill embankment for <br />Reservoir No. 15, Sec. 4, T. 9 N., R. 69 W., Larimer County, Colorado. <br /> <br />The embankment is an earthfill structure constructed in 1909 and raised <br />in 1948 to a height of 49 feet. The embankment is 2,650 feet long. A <br />preliminary repot:t for rehabilitation of the dam was prepared by Bruns, Inc. <br />under their Job No. 1,499 dated December 9, 1975. A soils and foundation <br />investigation was conducted by Empire Laboratories, Inc. under their Project <br />No. 2060-75 in 1975, <br /> <br />The embankment is apparently a homogeneous sandy, silty clay founded on <br />natural sandy, silty clay soils underlain by clay shale of the pierre Shale. <br />The pierre Shale dips a few degrees to the east. The Niobrara Shale <br />consistirg of interbedded limestone and silt and clay shale occurs i.'l1I1\ediately <br />'...est of the 'nest side of the reseC".Joic. The extrane western erd of tt'i€ <br />embankment extends onto the Niobrara formation. However, the majority of the <br />reservoir is underlain by the pierre Shale. <br /> <br />Based on our site visit and review of the pt:evious reports for the <br />project, we su;Jgest the followirq: <br /> <br />Scope of Wbrk for Additional Geotechnical Evaluation of the facility: <br /> <br />(1) Drill 3 exploratory roles in the existirq embankment, through the founda- <br />tion soils and into the pierre Shale. The roles will be drilled with 4- <br />inch continuous flight power augers and sampled by Shelby tube, <br />California and standard split spoon and bulk samples dependirq on the <br />soil types encountered. <br /> <br />( 2) Drill 2 exploratory roles to bedrock at the toe of the dam. Sample the <br />holes as discussed above. <br /> <br />OFFICES: CASPER. COLORAOO SPRINGS. GLENWOOO SPRINGS. SALT I.AKE CITY <br />