SITE INFORMATION AND CORRESPONDENCE FILE 1

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� � r Memorandum of Understanding Cox and Cox Site Summary of Field Work to date and May 18, 2000 meeting with PHS EHD. 1. Wright Environmental has an approved scope of work for additional assessment at the Site. This work was requested by the PHS EHD for additional assessment in and around MW-3 and MW-9 for possible contaminant source location based upon historic groundwater dissolved contaminant distributions. 2. The field work was performed on April 25, 2000 which involved direct push exploratory borings at the designated locations. Difficult drilling conditions of heaving and flowing sands caused numerous field delays. Also subsurface utility locations of the large pipeline (West Side Irrigation District) and City of Tracy (two sanitary sewer lines- one a large industrial line) caused problems. The irrigation line was full and the irrigation representative stated additional setback for line safety. The City of Tracy specificially requested that borings not be advanced to the east of the irrigation line due to inconclusive line location map accuracy. Consequently, three of the originally approved borings were not advanced. 3. The PHS EHD representative observed some of the field work, and discussed the boring data with the Wright geologist in the field on April 25, 2000. After a review of data and boring locations, as well as reviewing the proximity of the known source, it was decided to meet to discuss the site and additional approach for finishing the site vertical assessment and ability to drill holes in the sensitive utility area. 4. Wright met with the PHS EHD representative on May 18, 2000 to review the historic data and outline the approach to further assessment. It was decided to revise the approach and modify the approved scope of work to best address the following; Reporting of recent field work and regular quarterly monitoring will proceed. • Conduct geophysical survey of former tank area and driveway where irrigation and city sewer lines pass through the area requiring further definition of horizontal and vertical extent of contamination. • Pothole to locate irrigation as sewer lines as required to place additional soil borings near MW-9. • Define vertical extent under known former tank source by drilling and sampling to the underlying confining layer. • Define horizontal and vertical soil and groundwater east and south of MW-9. • Inspect the welding building and former service station building for potential contaminant sources (such as oil/water separators and sand traps).