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' Multi-Level Monitoring Well Installation Report - Fourth Quarter 2003 • PACIFIC CAR WASH ' 4405 Pacific Avenue, Stockton, California ' 1.0. INTRODUCTION AND SCOPE OF WORK Advanced GeoEnvironmental, Inc (AGE) has prepared this ground water monitoring well Installation report for 4405 Pacific Avenue (site), Stockton, California The report documents procedures and results for installation of multi-level ground water monitoring wells at the site during ' July and October 2003 and is in accordance with guidelines issued by the California Regional Water Quality Control Board(RWQCB)-Central Valley Region for investigations of underground storage tank (UST) sites The location of the site is illustrated in Figure 1, general features at the site are illustrated in Figure 2 A summary of previous investigations at the site was Included in the AGE- prepared Preliminary Site Investigation and Evaluation Report - January 1997, dated 15 January 1997 The scope of work of this investigation included installation of seven multi-level ground water monitoring wells(MW-13 through MW-19)with the objective of assessing the Impact of petroleum hydrocarbons to soil and ground water Based on soil data collected from previous cone penetrometer testing(CPT)results and comparison with descriptions from borings previously advanced on the site, AGE has developed a subsurface model of the site soil stratigraphy comprised of five informal ' hydrogeologic zones (Figures 3 and 4) Three hydrogeologic zones were identified as having significant intervals of apparently porous, coarser grained soil, and were identified as First Water Zone, between 15 and 40 feet below surface grade(bsg),Second Water Zone, between 70 and 95 feet bsg, and Third Water Zone between 115 and greater than 125 feet bsg These porous zones were separated by significant Intervals of finer-grained, less permeable soil,identified as First Confining Unit and Second Confining Unit Based on AGE's subsurface model, multi-level wells MW-13 through MW-19 were generally screened at depths of 35 to 40 feet(First Water Zone), 62 to 67 feet bsg (First Confining Unit), 79 to 84 feet bsg (Second Water Zone), 95 to 100 feet bsg (Second ' Confining Unit), and 120 to 125 feet bsg (Third Water Zone) The following is a brief summary of events for the July and October 2003 well installation activities performed at the site • 30 July 2003 - Soil boring for MW-13 advanced to 125 feet bsg, soil samples collected at five-foot intervals between 70 and 125 feet bsg,boring completed as multi-level monitoring well MW-13 (A-D) • 31 July 2003 - Soil boring for MW-14 advanced to 125 feet bsg, soil samples collected at five-foot intervals between 70 and 125 feet bsg,bonng completed as multi-level monitoring well MW-14 (A-D) • 04 August 2003 - Well development activities performed at wells MW-13 and MW-14 Advanced GeoFnveronmental,Inc I