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Geologcea'Technics lnc Page 5 GW Monitoring Report Ted Peters -AST Project No 701 2 July 31,2002 highest concentrations Additional monitoring is necessary to determine if the detection in MW-7 represents a detached plume from the former UST area or if it is sourced from ' a different release • Figure 5 illustrates TPH-D concentrations in groundwater in the vicinity of the foriner ASTs Wells MW-5 contained 130,000-µg11 diesel GTI's previous GeoProbe ' investigation revealed that the diesel contamination is limited to the area of former ASTs and associated dispensers ' 4 0 CONCLUSIONS & RECOMMENDATIONS Conclusions ' 1 Groundwater flow is predominantly to the northwest for both the AST and UST sites on this property GTI believes that previous southwesterly directions noted in the AST area are anomalous based on the presence of free product in MW-5 and/or the spatial orientation of the wells 2 TPH-G, TPH-D or volatile organic compounds are present in four of the five groundwater monitoring wells 3 The TPH-G concentration increased in MW-5 and decreased in the downgradient well, MW-7, which corroborates with the soil gas survey results (the soil gas survey report was submitted to the RWQCB on July 31, 2002) Recommendations 1 GTI has performed the soil gas survey, the report has been submitted to the RWQCB- CVR and it includes recommendations for additional monitoring wells 2 Maintain the current quarterly groundwater monitoring event schedule as required in the MRP 3 Discontinue analyses for VOCs on a quarterly basis and reduce the testing to annual in wells MW-4 through MW-7 This is a formal request for the Board to modify the MRP to reflect this request The reason for this change is that no chlorinated solvents are detected and the only VOCs found in these wells are related to the petroleum containination, not solvents 4 No further recommendations will be made for the diesel contamination issue until the ' results of the SGS have been commented on by the RWQCB-CVR ' 50 LIMITATIONS This report was prepared in accordance with the accepted standards and practices of the field of environmental geology, groundwater hydrology and good business practices It should be recognized that definition and evaluation of environmental conditions is a difficult and inexact science Judgments leading to conclusions and recommendations are generally made with an incomplete knowledge of the site-specific conditions present The tasks proposed and completed during this project were reviewed and approved by the local regulatory agency for compliance with the law No warranty, expressed or implied, is made I