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1. Toe Dam, Drains and Seep Water Ponds. <br /> Subdrains have been installed from the toe of the dam upstream for a <br /> distance of 1,500 feet. These drains, which are both trench and pipe <br /> drains, extend under the toe dam and discharge into seep water collec- <br /> tion ponds. All drains have been placed with a graded filter media <br /> progressing from cobbles to 1-2-inch pebbles to gravel to sand. Cutoff <br /> walls were placed around pipe drains to prevent any piping of sand that <br /> might occur. A drain header with manholes has been placed up the toe <br /> traces. Additional drains will be placed along the tailing-natural <br /> soil interface and tied into this header as the crest is raised each <br /> year. <br /> The toe dam was constructed of native materials and is primarily built <br /> of V-8" cobbles and sandy gravels with very few fines. All organic <br /> materials were removed from the site, and the only compaction used was <br /> that of the construction equipment. The toe dam was 70 feet high and <br /> had a crest length of 1,000 feet. In the area behind the toe dam, <br /> twenty-nine (29) piezometers have been installed in a grid pattern <br /> with 500-feet spacings between piezometers. <br /> All seep water flows into either of the two seep water ponds. These <br /> concrete lined ponds are designed to let any silt or slimes settle out <br /> before reaching the clearwater pond. Either seep water pond will handle <br /> the flow, allowing one pond to be used while the other is being cleaned <br /> out by a front-end loader or similar piece of equipment. <br /> t <br /> d <br /> A 7t r,� <br /> ' <br /> Figure 2. Overview Of Toe Dam Area, Showing Drains. <br />