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File No 2070-2 17 February 1993 Page 1 • Status of Site Activities A Problem Assessment Report (PAR) for the site was issued on 19 December 1991 by Anderson Consulting Group (ACG) The PAR summarized activities conducted at the site since the discovery in December 1986 of the release of petroleum hydrocarbons from two underground storage tanks Included in the PAR was a summary of investigations,conducted by both Environmental Sciences and Engineering (ESE) and ACG, to determine the extent of soil and groundwater contamination Additionally, a summary of soil remediation activities conducted by Tilford and Hall in 1987 was also included in the PAR Remediation of petroleum-impacted groundwater at the site has not been conducted,but is proposed Until a groundwater treatment system is on-line, the San Joaquin County Health Department has requested that quarterly groundwater monitoring be conducted m accordance with the State of California Regional Water Quality Control Board's Underground Storage Tank Regulations Groundwater Elevation The elevation of groundwater in each of the eight monitoring wells located on the subject site was measured and recorded on 23 December 1992 Only monitoring wells MW-1 and MW-8 contained sufficient water to allow specific groundwater elevations to be measured Since the groundwater elevation of only two monitoring wells could be determined, a site specific groundwater gradient for the final quarter sampling of 1992 could not be determined Based on historic data, this was the first monitoring episode in which the groundwater gradient could not be determined due to lack of sufficient water in the on-site wells. However, based on the two groundwater elevations obtained, it appears that the groundwater gradient slopes toward the east, consistent with past groundwater gradient calculations. Table I presents the groundwater elevation measurements Groundwater Sampling Sampling of the groundwater monitoring wells was conducted on 23 December 1992 Due to recent drought conditions, only wells MW-1 and MW-8 contained sufficient water to allow samples to be collected Prior to sampling, the monitoring wells were first purged of well casing water For monitoring well MW-1, the temperature, conductivity and pH of the groundwater was measured and recorded in five gallon intervals during purging This data was used as an aid in determining when an adequate volume of water had been removed from the well so that the true formational groundwater could be sampled A total of 27 0 gallons of groundwater were purged from monitoring well MW-1 Due to the limited quantity of groundwater in monitoring well MW-8, temperature, conductivity and PH readings were not obtained for this well Monitoring well MW-8 was purged of 10 gallon of groundwater until depleted, allowing the well to recharge with formational water The purged groundwater extracted from monitoring well MW-8 as well as monitoring well MW-1 was containerized in a 55-gallon drum and stored on the site AND \7 CONS CONSULLTINTfN G GROUP