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i <br />' TPE conducted the drilling and borehole soil sampling in <br /> accordance with the California Regional Water Quality Control <br /> Board' s (CRWQCB) "Tri-Regional Board Staff Recommendations for <br />' Preliminary Evaluation and Investigation of Underground Tank <br /> Sites" , dated August 10 , 1990 and Leaking Underground Fuel Tank <br /> Reference Manual (LUFT) , dated October, 1989 . <br />' Details of the scope of work are presented below. <br />' 3 . 1 Monitoring Well Soil Boring Investigation <br /> The following sections discuss soil boring and soil sampling and <br /> handling procedures, and results of chemical analyses. <br />' 3 . 1. 1 Predrilling Activities <br /> Prior to drilling TPE obtained well installation permits from the <br /> SJHCHSD (see Appendix A) and visited the site to mark the <br /> proposed soil boring locations . In addition, Underground Service <br /> Alert (USA Digs) was notified so that participating underground <br />' utilities in the vicinity of the borings could be located and <br /> marked. <br />' 3 . 1. 2 Drilling and Soil Sampling Procedures <br /> Five (5) groundwater monitoring wells were drilled and installed <br /> between June 13 and July 14 , 1992 using a Mobile B-61 truck- <br /> mounted drill rig owned and operated by Jcon Exploration, a State <br /> of California licensed water well driller (C-57 license #563305) . <br /> To prevent possible cross contamination between borings all bits, <br /> drill rod, and augers were steam cleaned prior to drilling each <br /> borehole. The monitoring well borings were advanced with 8--inch <br /> O.D. hollow stem augers and subsequently enlarged with 10-inch <br /> O.D. hollow stem augers. <br /> Representative soil samples were collected for stratigraphic and <br /> chemical characterization at approximately 5-foot or less depth <br />' intervals, or at changes in lithology. The samples were obtained <br /> by advancing a California split-spoon sampler, equipped with <br /> three 2-inch diameter X 6-inch long brass tube liners, into the <br />' undisturbed soil beyond the tip of the auger. A 140 pound safety <br /> hammer with a 30-inch drop was used to advance the sampler. The <br /> sampling equipment was cleaned before each sampling episode by <br />' washing in a trisodi.um phosphate solution and rinsing in tap <br /> water, and then distilled water. A TPE California Registered <br /> geologist logged each borehole and visually classified all soil <br /> samples according to the Unified Soil Classification System. <br />' Boring logs depicting the subsurface lithologies at each boring <br /> location are provided in Appendix E. <br /> All soil samples were inspected for any visual and physical <br /> indication of potential contamination ( 1. e , discoloration, odor, <br /> 3 <br /> 1 <br />