SITE INFORMATION AND CORRESPONDENCE

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y i Rond Property, Lode - 2 " August 13, 1943 San Joaquin County 111 r 5. Whether "Middle q 10'" indicates that the sample was collected in the middle of the excavation, near the middle of the tanks at a depth of 10 feet as assumed and whether "Fill end ® 10'" indicates the sample was collected at a depth of 14 feet; 6. The depth of the bottom of the tanks; 7. The total depth of the excavation; 8. The presence and locations of domestic or agricultural wells on-site and nearby; 9. The presence of ground water in the pit during excavation: 10. The results of any analyses of ground water samples collected from the pit and/or on-site wells; I ] . Depth to-ground water; and 12. Direction of ground water flow. WHAT WE NEED 13ceause we lack information about the conditions remaining at the site and the tank itself, we have nothing on which to base a closure request. Although, in this case not all data may be necessary, we do need a minimum on which to base our decision. The following information must be provided to the Board in a single report in order to consider site closure: 1. The information listed above; 2. Distance to production wells for municipal, domestic, agriculture, industry and other uses within 2,000 feet of the site; 3. Tabulated results of all sampling and analytical results (soil sample locations are to be marked on a site map); 4. Site maps, to scale, showing contours, ground water flow directions, buildings, streets, subsurface utilities, nearby surface waters, locations of former tanks, excavations, monitoring wells, borings, cone penetrometers; 5. High and low ground water levels (below ground surface) and historical high; 6. Extent of soil contamination (and ground water contamination if present); 7- Methods of cleanup used; ,g. Zone of influence, area of capture, and area affected by the cleanup methods; `�. Concentrations remaining on site; and 10. Rationale why contamination remaining on site will not adversely impact water quality, health, industry, agriculture, or other beneficial uses. Board staff concurs with the County request to install three wells as the most sure way to detect ground water contamination and determine the direction of ground water flow. (To determine the direction of ground water flow, it is necessary to have at least three measuring points.) Other methods may be used to detect ground water contamination, however, they are not as comprehensive and not as reliable. Alternative methods include installation of one monitoring well through the tank pit and/or area of highest soil contamination or use of cone penetrometer-type instruments such as The "llydropunch". ti r