2004-08-02_REVISION - M2000158 (3)

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07/26/2004 15:04 7208891383 PAGE 01 FIELD INVESTIGATTpN Lyman Henn has reviewed the CTL Thompson investigation dated 17 August 2001. Borings TH-15 and TH-l6 appear to fall within or adjacent to proposed Longhorn Lake. Bolings TH- 13and TH-l4 aze located several hundred feet to the south. CTL encountered the bottom of the gravel deposit in these four borings at depths of 22, 25, 25 and 27 feet. The stratum below the gravel is indicated by CTL to be "clay and/or claystone bedrock". Approximately 28 test borings vvi11 be performed to determine the depth sad quality of the bedrock along the stutry wall alignment. Borings will be spaced approximately 400 feet along the alignment. Tire scope of work for test borings includes laboratory testing, and report quality data presentation and dais interpretation. Detailed typewritten boring logs will be provided. Lyman Henn proposes to perform the following tasks necessary for test borings. • Meet with Envirocon and Platte Sand and Gravel to determine approach and extent of test borings. • Stake test boring locations and strange to have utility clearance prior to commencing a drilling program. • Perform test borings through alluvial material and into bedrock at designated locations. Test borings will be drilled by an experienced drilling company subcontracted to Lyman Henn. Test borings will be logged by a Lyman Henn .field representative. Alluvium will be drilled 10 feet into bedrock using hollow stem auger methods. Alluviur will be sampled and standard penetration tests will be performed in increments of 5 feet. Bedrock will be sampled and standard penetration tests will be performed in increments of 2.5 feet. If necessary and to determine their limits, more frequent sampling will be performed in the clayey soils. Samples of coazse alluvium, consisting of sand and gravel, and fine alluvium, consisting of overburden and play (mud) lenses will be collected for laboratory analysis for each boring. One out of every three borings will include coring 10 £eet of bedrock and packer testing. Packer testing will he performed to evaluate the competency of the bedrock for the slurry wall key. s Survey test boring locations. • Perform laboratory testing on collected samples. o Clayey Soils -Percentage of material passing the No. 200 sieve of clayey material, plasticity index of clayey material o Sand and Gravel -Percentage of material passing the No. 200 sieve of clayey material o Index properties will be determined on a total of ] 0 samples of clayey soils and on a total of 10 samples of sand and gravel Strength properties of the bedrock will be determined from UCS test results from each boring cored. l... WQRK PLAN NARRA'I:~VE Longhorn Lake Slurry Wall