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Construction Report -West Taylor Pond <br />This change was made because none of the available sources of borrow would meet <br />the original specification and this modification would have minimal impact on the overall <br />performance of the structure. However, given the slightly higher silt content in the <br />available borrow materials, it was determined that a drainage filter should be installed <br />underneath the lower one-third of the embankment footprint. Considering the hydraulic <br />gradients available, the risk of piping failure is marginally higher without this drainage <br />blanket. As completed, the drainage blanket intercepts any phreatic surface which <br />could exit at the downstream toe by providing a preferential drainage path through the <br />drain that is several orders of magnitude higher than the surrounding embankment. The <br />as-built drawing provides the specifications for the drainage blanket. <br />As shown on Attachment 2, the silt plus clay fraction of the borrow sources ranged from <br />56 to 67 percent, well within the specification to have at lease 25 percent fines. Any <br />rocks larger than 6 inches in maximum dimension were rejected from the embankment <br />fill. <br />Tom Peterson of Environmental Solutions, Inc. inspected the West Taylor Pond <br />construction on the following days, with these inspections previously scheduled to <br />identify critical construction events: <br />July 12, 2007 <br />July 20, 2007 <br />July 24, 2007 <br />July 27, 2007 <br />August 8, 2007 <br />August 13, 2007 <br />August 20, 2007 <br />August 28, 2007 <br />October 8, 2007 <br />July 18, 2007 <br />July 23, 2007 <br />July 26, 2007 <br />July 31, 2007 <br />August 9, 2007 <br />August 17, 2007 <br />August 22, 2007 <br />September 18, 2007 <br />October 18, 2007 <br />Alan Jorgensen and Kurtis Blunt also provided additional inspections. Generally, this <br />was done almost every day that work was underway. <br />Compaction testing was also conducted as directed by the field engineer. NWCC <br />Laboratories provided this service. Attachment A-3 provides the compaction test <br />results. Testing was done more frequently on the keyway and the lower lifts to establish <br />a method of uniformly achieving compaction. Actual compaction generally exceeded 95 <br />percent of maximum dry density. When a compaction test failed, a successful retest <br />was achieved before an additional material was added. Eighteen different tests were <br />done over four different days. <br />Page 3 <br />