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On the basis of this data, a dissolved plume of TPHD appears to have moved toward MW-2 and is assumed to possibly be under the Delta Disposal property just north of the former UST locations. The lack of BTEX and MTBE and related fuel volatile and oxygenate compounds is interpreted as an indicator of natural degradation processes occurring on fuels from the former USTs. 6.0 Conclusions and Recommendations Wright has completed the Limited Phase II Site Investigation Groundwater Monitoring Well Installation and Sampling Report at Delta Disposal 99 6t' Street in Tracy. Previous groundwater sampling at former underground tank locations in 6h Street revealed TPHG and TPHD contaminants. Additional soil and groundwater sampling performed for the well constru 2003. ction revealed TPHG and TPHD contaminants although at lower concentrations than those observed in Groundwater wells placed at approved locations into the shallow aquifer. An initial plot of groundwater flow showed a northwesterly groundwater flow direction. TPHG, BTEX and MTBE and related oxygenates were not detected in any groundwater sample. On the basis of the initial monitoring well sampling, a small dissolved plume of TPHD appears to have moved from the former UST locations north toward and possibly under the Delta Disposal property. It is Wright's understanding that a quarterly groundwater monitoring program will commence with the data reported herein as the initial quarterly monitoring event. The next quarterly monitoring will be scheduled by the City of Tracy and assumes that the same chemical analyses will be performed on the groundwater samples as those in this study. A copy of this report will be forwarded to the SJC/EHD and uploaded into the electronic State GeoTracker system. 7.0 Limitations This report has been prepared specifically for the City of Tracy for the public right of way in front of Delta Disposal Site at 99 6 Street in Tracy, CA and was done according to the current State and local agency suggested guidance documents for these investigations. The interpretations, conclusions and recommendations made herein are based on the data and analysis for the soil and water samples collected on-site. Conditions of the property can change over time and the use of this report by third parties is entirely at their own risk. Please note that reports of contamination must be submitted to the agencies in a timely manner. This report has been prepared solely for use by City of Tracy, our Client. This report shall not be relied upon by or transferred to any other party, or used for any other purpose, without the express written authorization of the City of Tracy. Wright Environmental Services, Inc. is not responsible for errors neither in laboratory analysis and reporting, nor for information not available, nor unreported or unknown sources of site contamination during the course of the study, and no warranty or guarantee is expressed or implied. Page 6 of 11