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 Page 4 Upper and Lower Emerald Valley Dam Failure Report <br /> January 23, 2015 <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />4.0 Description of Estimated Dam Geometries/Elements “Pre-breach” <br />As mentioned, these were considered “non-roster” dams, therefore this office has no <br />historical documentation of design, construction, or performance of these structures. The <br />following summarizes pertinent engineering characteristics of the dams based on post-breach <br />dam surveying collected by this office. Additional surveying information was obtained from <br />the work done in Reference #2 as part of the design and re-construction of the two dams. The <br />intent of the design/re-construction effort was to re-build the reservoirs to the same physical <br />dimensions as before, specifically as related to normal high water line and dam crest <br />elevations. This allowed the more accurate survey data to be utilized in estimation of pre- <br />breach stage area capacity information. <br /> <br />4.1 Upper Emerald Valley Dam <br />This structure was observed to be a unique one. At least 8 pipes ranging in size from 8 <br />inch diameter to 30-inch diameter penetrated the embankment from upstream to <br />downstream. Additionally, a septic tank was constructed in the left abutment/edge of <br />the old dam, with various pipelines that extended parallel to the dam crest to a leach <br />field on the right abutment of the dam. <br /> <br />4.1.1 Outlet / “Spillway” Configuration <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />Figure 3: 2011 Aerial Image Near Dams <br />Figure 4: Schematic Profile of U/S slope of UEV, facing downstream