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DIVISION 2 - SITE WORK <br />SECTION 02168 - SLURRY WALL CONSTRUCTION <br />PART 1- GENERAL <br />1.01 SLURRY TRENCH CUTOFF <br />A low permeability slurry trench cutoff wall shall be constructed to the lines, grades, and cross-sections as <br />indicated on the drawings. The trench shall have essentially vertical walls, a minimum width of 30", and shall <br />extend through the foundation materials and into the bedrock. A generalized description of the overburden <br />through which the slurry trench cutoff is to be excavated is indicated by summary logs of exploratory borings <br />included in the Drawings. <br />PART 2 - MATERIALS <br />2.01 SLURRY <br />Slurry shall consist of a stable colloidal suspension of bentonite in water and shall be controlled in accordance <br />with the most current API Standard 1313, "Standard Procedure for Testing Drilling Fluids," and the following <br />requirements: <br />A. At the time of introduction of the slurry into the trench, the slurry shall be a mixture of not less than <br />12.5 pounds per barrel (42 gallons) of bentonite and water. Additional bentonite may be required <br />depending on the hardness and temperature of the water and the quality of the bentonite. The slurry <br />shall have a minimum apparent viscosity of 40-seconds reading through a Marsh Funnel <br />Viscosimeter, a maximum filtrate loss of 30 cubic centimeters in 30 minutes at 100 psi, and a pH of <br />greater than or equal to 7 and less than 10. <br />B. The slurry mixture in the trench will have a unit weight not less than 1.03 gm/cc (64 pcf), not greater <br />than 1.40 gm/cc (87 pcf), or as approved by the Engineer. <br />C. The slurry mixed with backfill material shall be either slurry taken from the trench or slurry meeting <br />the requirements of slurry introduced into the trench. <br />2.02 BENTONITE <br />Bentonite used in preparing slurry shall be pulverized (powder) premium grade sodium cation <br />montomorillonite and shall meet the most current API Standard 13A, "API Specification for Oil-Well Drilling <br />- Fluid Materials." <br />2.03 WATER <br />Fresh water, free of excessive amounts of deleterious substances that adversely affect the properties of the <br />slurry shall be used to manufacture bentonite slurry. It is the responsibility of the Contractor that the slurry <br />resulting from the water shall always meet the standards of this Specification. <br />2.04 ADDITIVES <br />Admixtures of the type used in the control of oil-field drilling muds such as softening agents, dispersants, <br />retarders or plugging or bridging agents may be added to the water or the slurry to permit efficient use of <br />bentonite and proper workability of the slurry. However, no additives shall be used except as approved by the <br />Engineer. <br />4/08 Section 02168 - Page 1 of 5