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E. The Contractor shall be responsible for demonstrating to the satisfaction of the Engineer that the trench <br /> is continuous and keyed the minimum specified depth into the designated stratum. The Engineer will be <br /> available onsite to verify these measurements. Trench continuity shall be assured by the action of <br /> movement of the trench excavation equipment such that the digging tools can be passed vertically from <br /> top to bottom of the trench as well as moved horizontally along the axis of the trench without <br /> encountering unexcavated material. Penetration of the bottom of the trench into the designated stratum <br /> shall be demonstrated at 10 ft centers by observation of the excavation spoils from the trench and by <br /> direct measurement of the top of the designated stratum and the final excavated trench depth to the <br /> satisfaction of the Engineer. <br /> F. Materials <br /> 1. Bentonite: Manufacture's Certificate of Compliance with the API specification shall be obtained <br /> from the manufacturer for each shipment of bentonite delivered to the site. <br /> 2. Water: Water for slurry mixing shall be tested once for each change in water source as shown in <br /> Table 1. <br /> 3. Prepared Backfill: Soil-bentonite backfill shall be tested prior to placement in the trench by <br /> conducting tests to determine slump and density. Laboratory testing of the permeability shall be <br /> conducted once for every 1500 cu.yards of backfill mixed. Permeability testing shall be performed <br /> to verify the prepared material meets specification. Permeability determination may follow <br /> placement. <br /> 4. Fresh Slurry: A complete series of tests shall be conducted from the mixer or tank containing fresh <br /> slurry ready for introduction in the trench twice per shift and at least once per batch of slurry. <br /> 5. Trench Slurry: Slurry in the trench shall be tested at least twice per shift. Samples shall be obtained <br /> from the lower depths of the trench near the excavator. <br /> 6. Slurry Wall Performance: The completed slurry wall will be tested according to the"State Engineer <br /> Guidelines for Lining Criteria for Gravel Pits,"August 1999, Section 3.1. Water Budget Accounting <br /> frequency will be determined from the results of the test. <br /> G. Quality Control Testing Equipment <br /> 1. The field laboratory shall be provided and equipped by the Contractor for use by the Owner's <br /> Testing Agency with the following equipment, at a minimum: <br /> 2. Marsh funnel and cup—2 sets <br /> 3. Mud balance—2 sets <br /> 4. Sounding cable—2 sets <br /> 5. Slump cone and rod— 1 set <br /> 6. Sand content kit— 1 set <br /> 7. Standard 3", 3/8", 420 and 4200 sieve with hot plate(or microwave oven) and balance— 1 set <br /> 8. Filter Press <br /> H. Soundings shall be taken by the Contractor every 10 ft along the trench centerline using a weighted tape, <br /> cable or other device. Soundings shall be recorded to the nearest 0.25 ft. Soundings shall be performed <br /> by the Contractor and observed by the Engineer. Soundings shall record the following: <br /> 1. Top of Key, Less-weathered Bedrock Stratum: The top elevation of the key stratum shall be <br /> determined based on an examination of cuttings taken during excavation. <br /> 2. Bottom of Excavation: The elevation of the trench shall be determined subject to approval by the <br /> Engineer. <br /> 3. Bottom of Excavation Prior to Backfrlling; Soundings shall be used to monitor for sidewall collapse <br /> and accumulation of sediments. <br /> 31 66 17-10 <br /> Prowers Aggregate Operators, LLC <br /> West Farm Pit Phase 2 Slurry Wall Soil-Bentonite Slurry Walls <br />