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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />creek far downstrea~ of the da~ indicates it may be caused by a change in <br />foundation material at or near the level of the creek. The sand boils, <br />therefore, may represent the sporadic transport of near surface material <br />driven by seepage flo\'/ and not necessarily the transport of material over a <br />long distance fro~ within the foundation of the da~. <br /> <br />Seepage appears to be primarily through the sandy gravel foundation material <br />and is most intense where the dam is highest in the vicinity of the Main <br />outlet works. The seepage fl ow e~erges from the foundation above the ri ght <br />bank of the creek for a distance of several hundred yards downstrea~. At the <br />point of emergence the ground is boggy and the foundation has sloughed toward <br />the creek, forming bluffs ranging in height from three to 20 feet. The <br />instability has caused trees and bushes to topple into the bogs. Evidence of <br />seepage can also be observed along the entire left groin area as well, with <br />accumulated volu~e increasing toward the outlet structure. Seepage is also <br />prevalent along the left bank of the creek for an undetermined distance <br />downstream. Evidence of boils and deltas of fine gray sand can be detected at <br />various locations along the water line in the creek. This seepage, however, <br />does not appear to be related to the da~ but is apparently seasonal and is fed <br />from the steep hillside along the left side of the valley. When the reservoir <br />is at the current restricted level and in the past when water was stored above <br />that elevation, seepage al so e~erges along the toe of the dam at various <br />locations extending toward the right abutment. Much of this seepage is <br />concentrated at a low poi nt near stati on 8+00 and at the Hourgl ass outl et <br />works. On occasion seepage has been observed to emerge on top of the berm in <br />this section of the dam. <br /> <br />2.3 Outlet Works <br /> <br />2.3.1 Main Outlet Works <br /> <br />The Main outlet works invert on Beaver Creek is at elevation 9355 (G.H. 0). <br />It ori gi nally consi sted of a 36x48-i nch arch-shaped concrete conduit wi th a <br />wet well near the center of the dam ri si ng to the crest. The condui twas <br /> <br />2084H <br /> <br />-5- <br />