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. Purpose and Scope of Study This report presents the results of a Geotechnical Investigation and Rehabilitation/Repair Recommendations and Specifications for the Martin Cull Dam, which is located in Section 9, Township 10 North, Range 90 West of the 6th P,M. in MotTat County, Colorado, The approximate location of the project site is shown on Figure #1. A field exploration program was conducted to obtain information on subsurface conditions. Material samples obtained during the field investigations were tested in the laboratory to provide data on the classification and engineering characteristics of the on-site soils and bedrock materials, The results of the field and laboratory investigations are presented herein, . This report has been prepared to summarize the data obtained and to present our conclusions and recommendations regarding the slope failure, which occurred on the upstream face of the embankment, as well as to provide recommendations and specifications for rehabilitating/repairing the existing dam embankment Design parameters, specifications and a discussion of geotechnical engineering considerations related to the reconstruction and repair of the existing embankment are included, Existing Dam and Site Conditions It is our understanding that the existing embankment and reservoir were constructed in the 1950's, The existing embankment is approximately 53 feet high at the highest point and approximately 452 feet in length, The crest width for the existing embankment ranges from 12 to 15 feet and the surface is irregular, The slope configuration of the downstream face of the embankment ranges from 1.8 (horizontal) : I (vertical) to 2.25 (horizontal) : 1 (vertical) and appears to be in satisfactory condition, The upstream face of the embankment is very irregular due to the slope failure, which occurred in the summer of 2000, and the construction of access roads/drilling platforms required to complete this investigation, The undisturbed portions of the upstream face of the dam appear to have been constructed with slope configurations ranging from 2,5 (horizontal) : I (vertical) in the central portion of the embankment to 3,5 (horizontal) : I (vertical) at the ends of the embankment near the natural abutments. The existing topographic features at the site, as well as the location of the existing structures at the site are shown in Sheet 2 of the Construction Drawings, which have been submitted along with this report for approval. . The slope failure, which occurred along the upstream face of the embankment, appeared to range from 225 to 250 feet in length with a maximum vertical displacement of 6 feet The upper portion of the slide appears to be situated approximately 8 to 12 feet below the crest of the embankment and the toe of the failure appears to be situated near the toe of the embankment, The failed materials at the toe of the embankment appear to have pushed/rotated the intake structure for the outlet, which in turn left the gate valve inoperable, It should be noted that the reservoir was empty at the time of our first site visit in the fall of2000 and continues to remain empty, As requested by the State Engineer's Office, the outlet pipe was flushed out and video inspected, The outlet pipe was flushed out by Action Drain Services on August 29, 200 I and video inspected by Freedom Sewer and Drain on September 5, 2001. A copy of the tape produced during the video inspection was delivered to Sally Lewis, Assistant Division Engineer, Division of Water Resources in Steamboat Springs, Colorado on September 6, 2001. Based on the video inspection, it appeared that the outlet pipe consists of 12-inch diameter, smooth steel pipe welded in 18 to 22 foot sections, The pipe appeared to be in satisfactoty condition, however considerable amounts of corrosion/deposits were observed along the interior of the pipe, Two areas of excessive corrosion were also noted in . Job Number: 00-1660 NWCC. Ine, Page 2