Laserfiche WebLink
excavation, and 4) dry bentonite applied at an approximate rate of 1.5 percent of the dry weight of the <br /> backfill soil. <br /> QUALITY ASSURANCE TESTING <br /> Resident engineering services were provided by RMC during the slurry wall construction. These <br /> services included continuous on-site construction observation, surveying, sampling, field testing of <br /> ' various slurry trench parameters, and the assimilation of as-built information. A daily log of <br /> construction progress was kept. <br /> A material quality control program was followed throughout the slurry wall construction. Test types, <br /> frequency, and specified values are summarized on Table 1. In order to provide the quickest possible <br /> testing result turn-around time, a testing laboratory was set up on-site. Testing equipment included a <br /> Mud Balance, Marsh Funnel, Portable Electric Bench Oven, Electronic Scale, Portable Sieve Shaker, <br /> various Sieves, Wet Washing Apparatus, Ambient Temperature Filter Press, pH Meter, Sand Content <br /> Kit, and Slump Cone Apparatus. General field results, listed by station, are presented on Table 2. <br /> Specified field and offsite test results are shown in Appendix A. <br /> A rapid turn-around time of the test results allowed for near real time adjustments to the various slurry <br /> trench parameters throughout the project. Testing conformed with industry testing standards, <br /> including the American Petroleum Institute-Specifications 13-A, the American Petroleum Institute <br /> Recommended Practice-Specification 13-B-2, and ASTM C-143. Slurry viscosity, as measured using a <br /> Marsh Funnel Apparatus, and Unit Weight Values, as measured using a Mud Balance, were <br /> maintained in the lower end of the acceptable range (V>_40 seconds-Marsh, S.G. = 1.03 gm/cc to 1.40 <br /> gm/cc.) In a few instances the viscosity dipped below 40 seconds-Marsh due to an excess of water in <br /> the mix. These cases of low viscosity occurred at either the mixing pond or discharge hose. The <br /> viscosities were corrected at these locations so that the slurry viscosity in the trench was maintained <br /> above the minimum acceptable level. <br /> �V Filter cake formation of the slurry and filtrate loss was analyzed using an ambient temperature filter <br /> press assembly. Filter cake thickness and filtrate loss was consistently within the acceptable range. <br /> Texture of the cake formation ranged from clean to very sandy. The hydrostatic forces developed by <br /> the slurry combined with the filter cake formation on the trench walls, provided adequate support to <br /> hold the trench open with vertical walls. A sand content kit was used to measure the percent sand by <br /> volume suspended in the slurry. Sand content was found to range from 3 to 21 percent. <br /> -3- <br />