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PART 2 - MATERIALS AND EQUIPMENT <br />2.01 MATERIALS <br />A. Bentonite <br />1. The bentonite for use in the slurry trench shall be unadulterated powdered premium-grade <br />Wyoming sodium montmorillonite, or equal, as approved by the Owner/Engineer. <br />2. The bentonite, to be delivered, shall be tested by the Manufacturer and shall meet the <br />following requirements as determined from a mixture of bentonite and distilled water <br />prepared in accordance with API Standard Specifications, 13A, latest revision, and tested <br />in accordance with API Code RP 13B, latest revision: <br />A. Apparent viscosity: 15 centipoise minimum @ 68 degrees Fahrenheit <br />B. Filtrate loss: 20 cc max in 30 minutes @ 100 psi <br />C. Yield: 90 Barrels minimum <br />3. The use of chemically treated bentonite will not be permitted. <br />B. Water <br />1. Water shall be free of excessive amounts of deleterious substances, as determined by the <br />Owner/Engineer that could adversely affect the properties of the slurry or backfill. <br />2. The water shall comply with the following: <br />A. pH 6 to 8 <br />B. Hardness <50 ppm <br />C. Low dissolved salts, oil and total organic residue to allow proper hydration of <br />bentonite <br />C. Initial Slurry Mixture <br />1. At the time of introducing slurry into the excavations, the slurry mixture shall consist of: <br />A. A minimum of 5.5 % bentonite per unit weight of water (range 5.5 to 7%) with a <br />minimum unit weight of 64 pounds per cubic foot; <br />B. An apparent viscosity not be less than 12.5 centipoise (36 Marsh seconds) at 68 <br />degrees Fahrenheit as measured by the direct indicating viscometer; and <br />C. A filtrate loss not be greater than 20 cubic centimeters in 30 minutes at 100 psi <br />as measured by the filter press. <br />2. The Contractor shall add additional bentonite to make the slurry denser or more viscous <br />than the limits specified above, if deemed necessary by the Owner/Engineer. <br />3. Admixtures to alter the characteristics of the slurry in the trenches, including but not <br />limited to softening agents, dispersants, retarders or plugging or bridging agents, shall not <br />be permitted unless approved by the Owner/Engineer. <br />D. Slurry Mixture in Trench. The slurry mixture in the trench shall meet all of the following <br />requirements: <br />1. A unit weight greater than 64 pounds per cubic foot; <br />2. A unit weight at least 15 pounds per cubic foot less than the backfill unit weight; <br />3. A unit weight less than 85 pounds per cubic foot, or as approved by the Owner/Engineer; <br />4. A filtrate loss not greater than 30 cubic centimeters in 30 minutes at 100 psi as measured <br />by the filter press; <br />5. An apparent viscosity not less than 15 centipoise (40 Marsh seconds) at 68 degrees <br />Fahrenheit as measured by the direct-indicating viscometer; and <br />6. A sand content less than 15-20 percent as measured by API RP-13B, Sand Content Kit. <br />E. Off Site Materials for Slurry Wall Backfill <br />1. Materials shall be from a source approved by the Owner/Engineer. <br />2. Materials shall be free of roots, organic soil, lumps, trash and debris.