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I I I I I I I I I I I I I I I I I I I suitable material remain available for construction use. Silty sand with gravel from the crest of the dam was sampled for potential concrete aggregate. A cursory sei smi c ri sk eval uati on was performed due to the proximity of a faul t described as potentially active and because of the earthquake that was felt on October 18,1984. It was concluded that the fault should not be considered potentially active and that the epicenter of the 1984 seismic event was over 60 miles allay and should not be considered a threat to the dam. Nevertheless, a conservative value for horizontal ground acceleration of O.lg was used for stability analyses. The stability of the existing embankment was checked using the Modified Bishop method for the downstream slope under steady-state conditions, and the upstream slope during operational conditions. Pore pressures were estimated based on the steady-state phreatic surface derived from piezometric data. Material properties were assigned based on laboratory test results and experience with similar materials. The results of the stability analysis showed the upstream slope to have a factor of safety of 1.43 during rapid drawdown, and the downstream slope 1.53 under steady-state conditions. These safety factors meet minimum accepted standards of 1.2 and 1.5 respectively. Based on the site inspection, geotechnical investigation, stability analysis, and review of the dam's performance record, it was concl uded that .Barnes Me_a.QQILKe.s_ervoir: can _~_s_afelY-...Ql1erated at its present restricted le.ve.l. However, due to the danger posed by erosi on of the auxi 1 i ary spi 11 way, the - -- reservoir should not be raised above that elevation--.!!..~tJl the defi.f.ie_ncI~s ---- have been rep.aired. Therefore, it is recommended that storage be 1 imited to elevation 9083, or gage height 36.0 feet. This would represent a storage volume of 1,928 acre-feet. In addition, if rel1airs are not made to the outlet ~- - -----~ --~------ - --- works conduit in the-"-earf~tu.re, its condition_m~ghtdeteri~l"a.te to the point where-further restrictions would be required. In order to remove the restricti!l~~~estore ~_he.!eservoir storage capacity to its decreed volume, and to operate the reservoir:_~_afE!ly_in the future, a -- --~------ -- ---- --- --- number_oL defici~l1..cie~woul!LhavE!.J:o be l"ep~ir~~ These deficiencies are listed as follows, in order of importance to the safety of the structure. E-6 1151c