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The construction contractor is required to place at least five feet of Drain Cover Fill ("DCF") <br />over the synthetic liner in any area where the over-the-road DCF haul trucks are running. This <br />is more than we required in 1994 when the same type of trucks were used. It is not mandatory <br />to use five feet for liner protection; three feet would suffice, but in 1996 this requirement will <br />not adversely affect placement because the roadway will be in the area of initial stockpiling of <br />DCF for subsequent pushing, at the base of the slopes. <br />The specifications clearly require low-ground-pressure equipment and the contractor has <br />complied by supplying equipment that meets the low-ground pressure criterion. This equipment <br />can include low-ground-pressure D-8 and standard D-5 CAT dozers. (Standard CAT D-Ss as <br />well as standard D-6s will meet the pressure criterion.) In 1994 and 1995, standard D-8Ns and <br />D-9Ns were employed on the three-foot cover. This is a substantive decrease in pressure that <br />is reflected in the reduction of pressure that the liner will experience. <br />The dozers are prohibited from sharp turns and pushing of an amount of material than allows <br />the tracks to exceed the resistance to shear on the DCF and to effectively "excavate" DCF. <br />These incorrect procedures might create dynamic stresses that could be transmitted to the <br />synthetic liner. At 24 inches above the liner, CC&V is operating at least 6 inches above the <br />thickness at which liner distress (not penetration but rather scratches and indentations) was <br />observed in the single instance of a dozer blade encountering and damaging the liner (in 1995). <br />(This was a standard D-9 dozer in 1995.) As described below, the dozer pushing will be at <br />DCF depths of from 24 to 30 inches, such that the margin of safety will be greater than 6 inches <br />much of the time. <br />The dozers may only push uphill when ever the slope on the liner is greater than 4H:1V. <br />Throughout DCF placement in 1994 and 1995, almost all Drain Cover Fill was pushed in the <br />downhill direction because it expedited the placement by shortening the haul distances in many <br />cases and by distributing the loads by dozers in a downhill direction. In the single case of <br />encountering the liner and damaging it in 1995, it was a downhill push over a break in grade <br />that lead to the operator error. <br />CC&V is requiring a 50-foot grid of tube markers over any areas onto which DCF is being <br />placed and CC&V is requiring these markers at breaks in grade where the 50-foot grid does not <br />adequately mark these areas of synthetic liner located at higher elevations than the surrounding <br />terrain. These markers will be painted a notable color on the lower two-feet, they will be <br />another color in the interval from 2 feet to 2.5 feet above the liner, and will be a contrasting <br />color up to at least five feet. The color pattern will facilitate the dozer operator, the laborer, <br />and the CQA inspector to quickly ascertain and correct a lowering of the blade to less than 2-feet <br />above the synthetic liner. In 1994, the grid was a 100-foot grid with no requirements for <br />additional marking of breaks in grade. In 1995, the contractor relied on surveying for the grid. <br />CC&V is requiring one laborer and one Golder CQA monitor at each dozer that is pushing onto <br />the liner. The laborer (or the Golder CQA representative) is equipped with a portable tube <br />marker that will be set out in front of dozer in a manner that enable the holder to accurately <br />2 <br />