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<br />Santa Maria ReservOir. any <br />October 28. 1993 <br />Page - 2 <br /> <br />.' <br /> <br />anticipated to enable us to confirm the degree of stlbility of the embankment even when <br />saturated, enable us to develop a drain repair plan, and, if required, design an abutment <br />grouting program. These are the anticipated steps we feel appropriate based on the <br />existing information. We recommend that the work proceeds in phases with reviews of <br />the results of each phase as we progress. <br /> <br />SIte Visit <br /> <br />Harza's site visit on September 30, 1993 prmided the opportunity to examine the <br />condition of Continental Dam and its abutments. 1:be location of the piezometers, <br />upstream blanket, seepage areas and the left bank groin were observed. Discussions <br />regarding dye tests, inflow plugging methods and how the bottom outlet was extended <br />were held. <br /> <br />The surface geology is represented by a bedrock composed of latite, tuff and rhyolite <br />breccia. The rock is severely altered locally and where intact exhibits mutually <br />perpendicular vertical jointing and a prominent subhorlzontal joint set. The rock is <br />typically soft and weathered on the slopes. <br /> <br />Review of Conditions <br /> <br />Continental Dam was constructed in 1925-1926 as a compacted zoned earthfill <br />structure. The core contains a socketed reinforced concrete cutoff wall, clay core and <br />downstream filter section. The downstream slope is 2.5:1 (H:V) and composed of random <br />fill material. In 1991-1992 an impervious geotexti1e blanket was constructed on 2f3 of the <br />upstream face of the dam starting at the spillway c:levation. The blanket extended to but <br />not over the left abutment. <br /> <br />Previous Seepage <br /> <br />The dam has experienced seepage conditions dtning high reservoir levels throughout <br />much of its operational life (since 1942). Specific areas of seepage have been identified. <br />They are: <br /> <br />o Near the left abutment about 33 feet above the bottom of the original <br />outlet, width of this zone is about 30 feet. <br /> <br />o Seepage was noted above the (.utlet conduit to the "north" (the drawing <br />Figure 1-3 does not relate to that direction). <br /> <br />o Seepage was discovered near the left abutment about 213 of the way <br />down the top of the dam. <br /> <br />Page 6 of 15 <br />