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a f J beneath the site flowed in a northwest direction. The average hydraulic gradient on December 16, i 1996 was calculated to be 0.003 ft/ft or about 16 feet/mile. The data indicates a groundwater gradient that is consistent with the gradient last quarter. A summary of groundwater monitoring data is presented in Table 1. Groundwater elevations are referenced to feet above mean sea level. y Groundwater[samples were collected from monitoring wells MW-1, MW-2, and MW-3. Prior to collection of groundwater samples a minimum of three well casing volumes were purged. The depth-to-water, pH, electrical conductivity, and temperature were measured and allowed to stabilize before groundwater samples were collected. Additionally, Eh was measured in the groundwater purged from the wells. Samples were then collected from each well using disposable bailers. Purge water was contained in 55-gallon DOT approved drums. Purge water from monitoring well; MW-1 from the previous sampling event did not contain detectable concentrations of petroleum hydrocarbons and was discharged to the ground surface. Groundwater lwell purge and sample logs are provided in Appendix A. The groundwater''samples collected from each well were submitted with Chain of Custody Record to GeoAnalyticallLaboratories, Inc. in Modesto, California, a State Certified laboratory (DOHS 91157). The samples were analyzed for TPHg and BTEX by EPA methods 8015/8020, respectively; MTBE by EPA method 8020; and dissolved oxygen, carbon dioxide, alkalinity, nitrate, sulfate, and ferrous iron. Groundwater analytical results are summarized in Table 2. The Chain of Custody Record, laboratory analytical reports, and chromatograms are included in Appendix B. k ADDITIONAL SITE ACTIVITIES On October 30, ?1996, Smith Technology personnel supervised the removal of the monitoring well development and quarterly purge water stored on-site in 55-gallon drums by a licensed waste water hauler. The water was taken to a licensed facility for disposal. on December 13, 1996, Smith Technology conducted the disposal at a licensed disposal facility of the waste soil stored on-site inf 55-gallon drums from the previous investigation in July 1995. Copies of manifests are:included in Appendix C. On Decembei 24, 1996, Smith Technology replaced the damaged wellboxes for monitoring wells MW 1 and MW3!ion-site. The wells were apparently damaged by heavy truck and forklift traffic on-site. Heavier,!duty wellboxes were installed with a larger and deeper concrete apron. Copies of field notes!are included in Appendix A. j RESULTS OF LABORATORY ANALYSES Results of this quarter's laboratory analysis of groundwater samples from monitoring wells MW- 1, MW-2 and MW-3 indicate the presence of petroleum hydrocarbons in groundwater in monitoring wells BMW-2 and MW-3. TPHg and BTEX concentrations in wells MW-2 and MW-3 were detected at concentrations slightly higher than last quarter. In MW-2, benzene, ethylbenzene`and xylenes were detected at the highest concentrations since monitoring was wA951221Repoml 40MR]996.doc 4 • � sNrrH