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v fcs- t -_ " Ell S Harken Marketing Company of California Location#100966 Page 3 November 22,1991 designated a beneficial water use unit, locally the ground water is used for tike domestic water supply. Reportedly,ground wafter in the site vicini'y flows in a northwesterly direction towards the Stockton Diverting Channel(HMCC Workp'an. 1991), The depth to first ground water Is approximately 80 feet bgs as reported by SJCEH. 4.0 INVESTIGATIVE MEMODS 4.1 Borings On August 5,1991,a NEI geologist supervised the drilling and sampling of three soil borings at k the approximate locations shown in Figure 2. Drilling was conducted using subcontracted hollow-stem drilling equipment supplied by Wayne Drilling Company. The CME-55 drill rig was equipped with B-Inch diameter augers of five-foot lengths. Boring depths ranged from 40 to 50 feet bgs and were advanced In the approximate locations proposed In the HMCC Workplan. SJCEH was notified of the proposed activities 48 hours prior to commencement and provided a representative to observe the field activities. Boring B-1 was advancad 10 feet beyond the proposed depth of 40 feet to establish that ground water did not occur within a few feet of tl-.:infflul proposed depth. Borings B-2 and B- 3 3 terminated 41.5 feet bgs per the HM workplan. Soil sampling was conducted at five-foot intervals in the borings for logging and chemical analysis purposes. In addition,Boring 9-1 i was logged continuously with a five-foot long split spoon sampler to aid in the classification l $ of soil types and Identify changes In lithology. The use of continuous logging assisted in the identification of discontinuous strata relative to the other two borings. I � i � 4.2 Soil Sampling Protocol Relatively undisturbed soil samples were collected ahead of the drill stem at 5-foot intervals -inch long,2.5-inch diameter Split-Spoon Sampler(SPS) or an 18-Inch long, using either a 24 i 2-inch diam3ter SPS. The five-foot long continuous sampler was used only for logging purposes in Boring B-1. Sampling was performed through the center of the hollow drill stem. i., Blow counts were recorded on the boring logs for those samples collected with the 2.5 —.4 diameter sampler(Appendix A). The SPS was driven 18 Inches or until refusal with a 140- _ _ _ -- Refusal isctefined as penetration of less than six-inches pound hammer dropped 30 inches. -•--- 1"9 NA