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GeclogcealTech csInc Page 4 ' GW Monitormg Report Ted Peters -AST Project No 701 2 April 24,2002 ' A chain of custody document, listing all samples collected, accompanied the samples from field to laboratory, thereby providing a means to track their movement and insure their integrity All water purged from each monitoring well was placed in a 55 gallon DOT approved ' container, properly labeled and stored on site 2.3 Groundwater Sample Analyses ' Groundwater samples from each well were submitted to K1FF Analytical (State Certified Laboratory #2236) and analyzed for • BTEX by EPA method 8260B ' • TPH-G by EPA method 8260B • TEPH-D by EPA method 8015M ' • Volatile Organic Compounds by EPA method 8260B • MTBE, TBA, TAME, DIPE & ETBE by EPA method 8260B • Methanol and Ethanol by EPA method 8260B ' A groundwater sample from each well was submitted to California Laboratory Services (State Certified Laboratory#1233) and analyzed for M • Dissolved Lead by EPA method 200 8 A Chain of Custody was completed for all samples collected and tracked to ensure sample integrity The results and the detection limits for these analyses are listed in Table 2 of ' Appendix A, while the lab analytical results are presented in Appendix B ' 3.0 FINDINGS AND DISCUSSION The results of the groundwater sample analyses show the following 1 • Groundwater samples from four of the five AST monitoring wells (MW-4, MW-5, MW- 6 and MW-7) reveal the presence of TPH-G or gasoline constituents • Wells MW-5 and MW-6 contain TPH-D at 62,000 and 190 µg/l, respectively ' • Free diesel product (approximately 0 2 inch) was detected in MW-5 for the event and has been detected in MW-5 during previous events • Well MW-8 did not contain contaminant concentrations above the laboratory reporting limits for the third consecutive event This well is cross gradient to the former AST location and down gradient from the former UST location • Oxidation-Reduction Potential (ORP) measurements (Table 3) suggest that several of ' the wells are in the core of the contamination plume or are immediately down gradient of the plume Negative ORP values indicate that the wells are within the halo of reaction depleted water caused by biodegradation of the contaminants For the March ' 18, 2002, event, MW-4, MW-5 and MW-7 had negative ORP values MW-6 is upgradient of the primary contamination sources (diesel ASTs) and MW-8 is perpendicular to gradient