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Only 0.4 ppm TPHD was detected in the underlying confining strata soil sample in B-1, `..• and contaminants were not observed in the B-2 underlying confining strata soil sample. The TPHD in these soil samples did not match the laboratory diesel standard. TPHD was detected in the Water Well sample at 69 ppb,just over the detection limit. The TPHG and TPHD data for B-1 water samples did not match their laboratory standards, suggestive of a highly degrade fuel contaminant depleted in volatile content. In our opinion based upon this information, the previous tank removal and soil excavation appear to have removed the bulk of contaminants. Very low concentrations of residual TPHG and TPHD contaminants remain in the capillary fringe region at B-1, and dissolved degraded TPHD occurs in the shallow groundwater. The Water Well showed very low concentrations of TPHD, but the compound did not match the laboratory standard. In our opinion, the site assessment data do not indicate the former on-site tanks as a source since; the well location is just off-site and side-gradient (westerly) to the former tank pits, and the well seal exists through two underlying confining strata and taps water from an aquifer which occurs below 101-feet. Wright recommends discontinuing use of the Water Well for drinking water (if so used) at this time, and resampling the Water Well to ascertain whether the TPHD is present. The data will be used to verify contaminant presence and to ascertain whether the hydrocarbon could be an oil associated with use in the water well pump. Upon review of this report and direction from PHS EHD, Wright will prepare the workplan for monitoring well placement, if required, as discussed in our previously approved workplan. Limitations This report has been prepared specifically for M&M Builders site at 8111 West Eleventh Street in Tracy, CA and was done according to the State and local agency suggested guidance documents for these investigations. The interpretations, conclusions and recommendations made herein are based on professional judgment of the data and analysis for the soil and water samples collected on-site and should be reviewed in the context of this report and other site reports. Wright Environmental Services, Inc. is not responsible for errors in laboratory analysis and reporting, nor for information not available during the course of the study, and no warranty or guarantee is expressed or implied therein. If you have any questions, please call. Smcerely, Wright Environmental Services, Inc. 1 P;° 1262 CERTIFF: D '� John Lynch Christopher M. Palmer E':2 '2=Fr(IiNG G2vLCGST President HG 246, CEG 1262 Attachments: Table 1. Soil Chemical Data ---- Table 2. Groundwater Chemical Data Figure 1. Boring Location Map and Reconnaissance Groundwater Map Figure 2. Dissolved Contaminants Groundwater Map Figure 3. Geologic Cross Section Page 5