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f Once the well had been purged, a water sample was collected as described above using a teflon bailer lowered into the well with new, clean monofilament line. Water collected in the bailer was- poured directly from the bailer into laboratory prepared sample bottles. This second sample was submitted for analysis of BTX&E by EPA Method 602 . For the initial groundwater sample collected on April 2, 1990, no TPH concentrations were detected. For the BTX&E compounds, toluene was detected at 0. 87 ug/L and xylene (total) was detected at 0.97 ug/L. In order to confirm the analytical results from the initial. groundwater sample, a i confirmation sample was collected on May 2 , 1990. This sample was analyzed i for both TPH and BTX&E compounds. The compounds analyzed were not -detected in the confirmation groundwater sample. Upon receipt of the initial sample analytical results, the Environmental Health Department (EHD) raised a question regarding the.' detection limit utilized for the TPH analysis of 'the groundwater samples. This detection limit, 0. 5 mg/L, was. not in compliance with the minimum recommended detection limit as established in the "Tri-Regional Recommendations" of 0. 05 i mg/L. As is stipulated in the Tri-Regional Recommendations, when a recommended detection limit is not achievable, sufficient justification F should be provided. This justification from the laboratory is provided below: "The laboratory wishes to address the concerns regarding the reporting limit of 17 .ng/kg for Method 8015 Modified for the Analysis of TPH. Please note that this method is the only method approved by the State of California Department of Health Services for TPH (gas and diesel) analysis. The limitations of Method 8015 Modified are that the lowest concentrations that can be reliably reported are 17 mg/Kg in soil, and 0. 5 mg/L in water. Detection limits may vary depending on the presence of interferences or the moisture content in a solid sample. " Because WESTON Analytics -- Stockton is certified by the State to analyze drinking water, wastewater, and hazardous- ' waste, we are bound by the requirements of our certifications to -follow procedures ' outlined in! State I approved methods. At the time of certification, our laboratory was required h' to submit data demonstrating the lowest level that could be reliably quantified following the procedure verbatim. This data and our reporting limits were approved by the State. I` CONCLUSIONS; Residual contamination is still present in the soil under the removed pipeline and the Tank 2 area. of the two rounds of water samples collected, the first set of samples detected toluene and xylene, while the confirmation sampling showed non- detection. i i 4 I s