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.~• Mr. Jim Mattern July 6, 2006 Page 2 900 ft downstream from the proposed dam, which is just beyond the Trapper Mine property limit. These existing impoundment dams are similar in construction to the proposed dam and appeaz to be in good working condition (Photo 4). The ground surface and vegetation downstream of the existing dams indicate no appreciable leakage despite the presence of minor vermin burrows beyond the downstream toe. The aerial photo in Photo 5 shows both the existing and proposed dam locations. There is a power line that runs up the gulch, and the neazest power pole is approximately 75 ft downstream. The pole is not expected to pose a problem for embankment construction. Qne of the two power lines is about 25 ft off the ground and will likely need to be moved for construction equipment clearance. The ground along the left abutmem (looking upstream) contains medium-density forestation with primazily deciduous trees and brush. As part of this site visit, no on site exploration holes, trenches, or samplin~ were preformed. The expected soil profile is based on the terrain and previous sampling. It is expected to consist of a thin layer of organics (-1-2 ft) followed by sihy alluvial sediments (-4- 5 ft) and underlain by weathered bedrock at depth. The local soils appeaz to have been used to construct the existing upstream and downstream drainage impoundments. EXPECTED SOll. CHARACTERIZATION Previous soil investigation performed for West Horse embankment dam included soil samples being collected at Deal Gulch impoundment site. The work was performed and reported by Montgomery Watson.' During their site investigation, at least one Shelby tube sample was retrieved from the Deat Gulch dam site. A summary of the laboratory analysis of the sample is given in Table 1. The exact sample location is not known and was not documented in the report. It is assumed that the tested sample is represemative of the expected foundation material given that the proposed dam site location has not changed since the samples were taken. Table 1. Summary of Soil Testing Results (from Montgomery Watson 2000)• Atterberg Grain Size Standard Proctor Limits IRstribidion 3Iw'eitic Com paction Sample USCS Soil LL PL Pl '/.° #4 #200 Gra~ty Dry Unit Moisture Depth Classificaflon Weight Content (DCf) (%) Fast Plume 13azrow SC 29 18 11 100 ] 00 50 2.64 114.1 13.8 I>eal Foundation SM NP NP NP 100 98 39 2.59 Tests were performed on borrow material that were to be used to construct the embankment for West Horse Dam. Grain size analysis resuhs aze shown in Figures 1 and 2 for ~ Montgomery Watsm (2000), "Proposed West Hesse Embanlmient Dam---Preliminary Slope Smbility Analysis," October. Agapito Associates, Iris.