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Mr Edward C Ralston Unocal Corporation . December 5, 1996 Page 3 Momtorma Well Development_and Ground Water Level Measurements Monitoring wells MW-1 through MW-3 were developed on September 6, 1996, using a surge block and by pumping 10 well casing volumes of water from each well The volume of water removed during development was based on turbidity and fine materials present in the water During September 1996, the tops of the well casings were surveyed relative to mean sea level by Morrow Surveying (a licensed land surveyor) A ground water contour map using the September 9, 1996, water level data and the surveyed elevations is presented in Figure 3 Ground water measurements and physical observations for the site are presented in Table 2 Based on the September 9, 1996, ground water level measurements, the inferred direction of ground water flow was towards the northwest, with a hydraulic gradient of less than <0 01 Ground Water Sampling and Analytical Results Ground water samples were collected from each monitoring well on September 9, 1996, and were submitted to Sequoia Analytical laboratory for analysis of BTEX, MTBE, TRPH as gasoline, and TEPH as diesel using the previously mentioned EPA Methods Analytical results for ground water samples collected from MW-1 through MW-3 did not report detectable concentrations of BTEX or TRPH as gasoline Detectable concentrations of MTBE ranged from 230 micrograms per liter (jcg/L) in MW-1 to 4,100 uglL in MW-3 TEPH as diesel was reported in concentrations ranging from 54 j.g/L in the sample from MW-2 to 130 ug/L in the sample from MW-3 Analytical results for samples collected on September 9, 1996, are summarized in Table 3 A copy of the laboratory analytical report with chain of custody documentation is included in Enclosure H RecommendationslC onclusions Based on the initial concentrations in ground water, Delta recommends the initiation of a quarterly monitoring and sampling program to evaluate water cheinistry, hydraulic gradient, and flow direction. Ground water elevation changes over one hydrogeologic cycle should be monitored in conjunction with petroleum hydrocarbon concentrations to evaluate if possible changes in the ground water elevation affect the reported concentrations in ground water Remarks/Sigpatures The interpretations contained in this report represent our professional opinions, and are based in pan, on information supplied by the client These opinions are based on currently available information and are arrived at in the accordance with currently accepted hydrogeological and engineering practices at this time and location Other than this, no warranty is implied or intended