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- 5 - <br />of 68° to 90'. The joint surfaces examined are mostly tight and <br />• smooth, with isolated joints showing soae limonite, carbonate and iron <br />staining. The joints oomronly occurred in localized sets and appeared <br />discontinuous across the site. <br />Engineering Geology Aspects: The faulting observed at the site is <br />believed to be contemporaneous with the Ffiite River uplift of late <br />Eocene and middle -~iocene age (last 20,000,000 years). No evidence of <br />more recent movement was observed. The faults observed are considered <br />low activity faults and, in our apinio~n, do rot present an unusually <br />high earthquake risk for the type of construction proposed. While a <br />seismic coefficient of 0.0259 is considered appropriate for Seismic <br />Zone 1, seismic risk of 0.059 has been incorporated in our stability <br />analysis. Other faults have been mapped in the general area. Seismic <br />activity in the area is generally associated with faulting, but the <br />• faults are considered miror and not capable of generating large <br />earthquakes. <br />in our opinion, the geologic conditions at the site do rot <br />present a major hazard to the proposed construction. We do not <br />anticipate any unusual problems associated with the site geology <br />provided that rormal sound engineering practices are observed. <br />FIELD INVFSi'IGATIO.I. The subsurface conditions of the present <br />refuse pile were determined by drilling five test borings at <br />approximate locations shown on Figure. 2. The existing refuse material <br />• <br />lOpen file report "Earthquake Potential in Oolorado", Oolorado <br />Geological Survey, 1978. <br />