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III. Field Observations, In-Situ Measurements, and Sampling Wells MW-1, MW-2, MW-3 and MW-4 were sampled on June 23, 2003. Each monitoring well was purged using calculated weii volumes based upon the depth to water in each individual well casing. Depth to groundwater measurements were made to the nearest one-one hundredth of one foot, and also checked for the presence of separate phase product. As each purge volume is removed, measurements of pH, electrical conductivity, dissolved oxygen and temperature were taken until these parameters stabilize, which is interpreted to be aquifer water entering the casing. Each well was allowed to recover to about 80% of the initially measured water level, and then samples were collected. The sample was carefully collected with a clean bailer and poured into the appropriate laboratory prepared container with minimum cavitation. The well field sampling note sheets are summarized in table 1 as set forth below. 111.1. Field Quality Assurance/Quality Control (QA/QC) Measures TRE and PET employed strict field QA/QC measures to ensure the integrity of the samples and the field operations. Each water sample was properly labeled, logged onto a chain-of-custody form, and placed in a chilled ice chest to preserve the samples by maintaining an approximate temperature of 4C° for storage and transport to the laboratory as recommended by EPA. New disposable bailers were used for sampling each well. PET decontaminated the monitoring wells purging equipment (tubes, pump, etc) between wells by purging it with Alconox detergent and DI water solution and rinsed with DI water. Care was taken by PET to ensure that samples are not crossed contaminated. Upon completion of well sampling, the well was closed and locked and the sampler moved to the next well. All in- situ field measurement equipment (pH meter, EC meter, etc) was properly calibrated by PET in the morning prior to the commencement of field operations. Table 1. Groundwater Monitoring Well Data WELL DEPTH TO WATER (FT) WELL DEPTH (FT) CASING ELEVATION (MSL FT) GROUNDWATER ELEV. (FT) COMMENTS MW-1 8.95 22.20 6.95 -2.0 None MW-2 4.20 22.50 6.00 1.8 None MW-3 7.70 20.80 3.50 -4.2 None MW-4 7.20 22.75 6.20 -1 None All metal samples were properly filtered when they arrived at the laboratory (PET) shortly after all samples were taken. Laboratory filtration was preferred over field filtration due to the fact that foreign artifacts/particles may potentially be introduced to the samples while being field filtered on site. This is particularly true in any industrial setting such as the port of Stockton, where field conditions 5