Laserfiche WebLink
Lined Pit Guide 3 September 2000 <br />bentonite, 20-40 percent fines, and has a moisture content of 25-40 percent. The density of the slurry in <br />the trench must be at least 15 pounds per cubic foot less than the density of the S-B backfill to displace <br />the slurry in the trench during backfilling. <br />Working Platform and Layout Drawing <br />An S-B slurry wall generally cannot be constructed in areas with a slope greater than 2 percent along <br />the alignment. Site preparation may require the construction of a clear and stable working platform 40 <br />to 60 feet wide and at least 5 feet above the ground water level. The layout of the slurry wall should be <br />illustrated on a 1"=100' or other appropriately scaled drawing showing property lines, coordinates, <br />contours, existing facilities, and drill hole locations. The erosion control plan should also be illustrated <br />and described. It is important to route runoff away from the trench to protect the purity of the slurry. <br />Bentonite <br />The design documents or other preconstruction submittals should include the bentonite manufacturer's <br />certificate. of compliance. If these are unavailable during permitting they may be provided.with the <br />final construction report and certification, but the standards to be met must be in the technical <br />specifications. Bentonite standards are described in American Petroleum Institute (API) Standard 13A. <br />The following example specification is typical for bentonite. <br />YP/PV ratio API Std. 13A less than 3 <br />Viscometer greater than 30 <br />Filtrate Loss less than 15 cm3 <br />Moisture Content ASTM D 2216 less than 10 percent <br />Test results for each lot of bentonite must be provided. The specification should describe how the <br />bentonite will be stored at the site. <br />Water <br />Suitable water must be used in the preparation of the bentonite slurry. Water that does not meet <br />specifications must be treated or conditioned or another source of water located. An example of a <br />typical water specification follows: <br />pH <br />Hardness <br />Total Dissolved Solids <br />Oil, organics, acids, alkali <br />Chloride <br />6-8 <br />less than 200 ppm <br />less than 500 ppm <br />less than 50 ppm each <br />report