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16 Prior to collecting samples, groundwater surface elevations in the monitoring wells were measured to define the groundwater hydraulic gradient Measurements were made using an ' electrical water level meter graduated in tenths of inches The measured elevations were reduced to the survey control benchmark Table 3 lists the groundwater surface elevations measured in the wells for this quarterly monitoring event, and past monitoring events ' Prior to sample collection, each well was purged of stagnant groundwater utilizing a 2-inch submersible pump Purging continued until either the well pumped dry, or stable field measurements of temperature, pH and conductivity were obtained in the groundwater being purged Table 4 presents well purge data Following purging and before sampling each well was allowed to recover to at least 80 percent of the initial water level in the well All wells were sampled with the submersible pump Groundwater samples were collected into laboratory supplied 32 ounce amber glass containers and 40 ml clear glass VOA vials, all with Teflon lined lids Each container was completely filled allowing no headspace following placement of the Teflon-lined lid Following transference, each sample container was labeled, logged on a Cham-Of-Custody form, and placed in an ice chest to be kept at 40°C during transport to a State of California certified analytical laboratory Table 4 lists sample identifiers and analytical results for each constituent analyzed Analytical reports and completed Cham-Of-Custody are presented in Appendix A Prior to initial use and between subsequent purging events the submersible pump used for well purging was field decontaminated by submerging the pump in a mixture of Alconox and clear ' water and pumping approximately 10 gallons of the mixture through the pump and the discharge line Discharge was contained in a 55-gallon steel drum and securely stored on the Site The pump was then removed and rinsed in clear water, rinsed in distilled water, rinsed in deionized water, and allowed to air dry The outer surface of the discharge line was washed in clear water, washed in a mixture of Alconox and clear water, rinsed in clear water, rinsed in distilled water, rinsed in deionized water, and allowed to air dry ' 6.0 CONCLUSIONS ' 6.1 GROUNDWATER SURFACE AND GRADIENT Groundwater surface elevations measured during this quarterly monitoring event decreased in ' every well, relative to groundwater surface elevations measured in the same wells during the conduct of the initial contamination assessment in February 1994 ' Average water table elevation on 2 March 1994 was 46 26 feet BGS for the three wells By 24 October 1994, the average water table elevation had dropped to 47 44 feet BGS, a average drop of 1 17 feet over approximately 5 months 366-001 -7-