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FIELD REPORT GROUNDWATER MONITORING PROGRAM 7759 S. AIRPORT WAY STOCKTON, CALIFORNIA On 16 June 1995, Ro F Weston Inc TON sampled the monitor wells located at 7759 7 y (wEs ®} p South Airport Way in Stockton, California The purpose of this work was to monitor for the presence of petroleum hydrocarbons in groundwater in the vicinity of two former USTs at the facility and to develop long-term data on groundwater gradient variations Prior to sampling, water level measurements were taken from all three wells at the site. The standing water volume within each well casing was calculated using the data obtained from the water level measurements All wells were purged a minimum of three well casing volumes. The purged water was contained in four labeled drums and left at the site ' Measurements were taken for temperature, pH and electrical conductivity of the purge water after each well volume was purged This information was recorded on field water sampling data sheets Purging of the well continued until a minimum of three well volumes had been removed from the well Samples were collected using a Teflon bailer and were carefully poured into laboratory prepared glass bottles The sample bottles were labeled with stick-on labels filled out in indelible ink with the following information site name, date collected, time collected, sample ID, sampler's initials and analysis required The samples were designated with ID numbers that corresponded to the well from which they were collected Samples were then individually sealed in resealable ziplock bags and placed with ice in an insulated chest for delivery with a chain-of- custody document to Sequoia Analytical Laboratory in Sacramento, California This laboratory is certified by the State of California to perform the required analyses Samples were submitted for analysis of benzene, toluene, ethylbenzene and xylene by EPA Method 8020 and total petroleum hydrocarbons as diesel by EPA Method 8015m Quality control/quality assurance procedures consisted of the collection on a blind duplicate, which was collected concurrently with MW-3 and was given the fictitious well/sample name MW-4 The down-hole equipment used to purge and sample the wells (including bailers, pumps, purge lines, etc ) was decontaminated prior to each use The pump that was used to purge the wells was decontaminated by pumping an alconox-water mixture through the pump and purge lines. The exterior of the pump, associated lines, and the Teflon bailer were also washed with the alconox-water solution using a brush All equipment was rinsed with potable water and a final spray rinse of distilled water The nylon line used to lower the bailer into the well was disposed of after each use I All water sampling was performed in accordance with WESTON's site specific health and safety plan, which was available on-site during field activities A safety meeting was held before work began in order to review anticipated safety hazards and emergency procedures The field work for this project was performed under Level D personal safety protection L TROIECl3LSANJOQSTMAD•2ND QTR 1 26 July 1995