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a <br /> - salumossV 'JQEb <br /> August 8, 1983 <br /> Project 11671.4 <br /> - 2 - <br /> ' Y. <br /> B LINER CONSTRUCTION . <br /> The liners which remain to be constructed i.e. , the gest trench wall and <br /> the compacted berm along the southern margin of the operations area will <br /> involve placing liner material in 6 inch compacted°lifts. This will be <br /> accomplished by placed 8 to 10 inches of soil material and compacting to ~ <br /> 90 percent of maximum density with a segmented steel wheel compactor to <br /> form a 6 inch liner. The liner material will be carried to its full <br /> thickness by repeating this procedure. <br /> The entire 350 feet of the north end of trench #4 is underlain by a 2 <br /> foot compacted clay liner. Core sampling of this floor liner will take <br /> place in accordance with the agreement made with staff of the RWQCB##5. <br /> Core samples will be obtained in an undisturbed condition and tested for <br /> permeable from each 6 inch interval of liner. These undisturbed sample <br /> pairs will then be tested for permeability, one using leachate and the <br /> other water. <br /> C. PERMEABILITY TESTING <br /> Based upon ,on our recent discussions, we assume you agreed with the <br /> testing procedures submitted with our original proposal. All future <br /> testing will be accomplished using the same techniques as outlined in the <br /> original U.S. Army Corps of Engineers Manual., <br /> Newly constructed side wall liners will be core sampled during the <br /> construction process. Random samples will be tested for permeability at <br /> the rate of l pair of samples for each 10,000 feet of liner surface area. <br /> The following information is submitted as the equation for determining <br /> permeability of soil samples using the methods submitted in our original <br /> proposal. <br /> permeability k - 2J Al 1og10 -hm' <br /> 4(tl-t0) ; hl <br /> in which a = cross sectional area of standpipe (cm.) <br /> L = length of soil sample in permeameter (cm.) <br /> A = cross sectional area of permeameter (cm.) <br /> to ---time when water in standpipe is at �ho (sec.) <br /> ti = .time when water"iri standpipe is at hl (sec.) <br /> hohl = the heads between which the permeability is determined <br /> Based upon the information contained in our original proposal and on past <br /> experience on this site, borrow material obtained from' on-site sources is <br /> capable of achieving compacted liners with permeabllities of 10-6 cm/sec <br /> or less. <br />