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y Site Assessment Report <br /> Former Texaco Service Station <br /> Chevron Site ID 309075 <br /> March 18, 2010 <br /> .r <br /> 3.2.3.1 Field Procedures <br /> Groundwater purging and sampling was performed using the following procedures: <br /> • During the purge cycle, groundwater field parameter measurements consisting of <br /> specific conductance, pH, turbidity, color, odor, dissolved oxygen, oxygen reduction <br /> potential and temperature were measured using a groundwater quality meter <br /> • Approximately 10 times the volume of standing water was purged from the newly <br /> installed monitoring well, MW-6, and approximately six times the volume of standing <br /> water was purged from the newly installed monitoring well, MW-6D, due to the slow <br /> `r recharge rate. The monitoring well dewatered twice during the development. Field <br /> parameters were recorded on a well-volume basis <br /> • After the purge cycle was complete, a groundwater sample was collected for analysis <br /> with a disposable bailer and transferred to the appropriate laboratory-supplied sample <br /> containers prefilled with preservative. <br /> 3.2.4 Quality Assurance/Quality Control Plan <br /> Quality assurance/quality control (QA/QC) samples inclusive of trip blanks were submitted for <br /> laboratory analysis. A laboratory supplied trip blank accompanied each sample delivery group. <br /> QA/QC samples were analyzed for TPH-GRO, BTEX and MTBE for all laboratory submissions. <br /> 3.2.4.1 Groundwater Analysis <br /> Following well development, groundwater samples were collected from monitoring wells MW-6 <br /> and MW-6D. Subsequent to collection, samples were packed on ice, cooled to approximately 4 <br /> °C, and shipped, under appropriate chain-of-custody protocols, to Lancaster for analysis. <br /> Analyses for all groundwater samples included the following parameters: <br /> • TPH-GRO (C6-C12), TPH-DRO (C10-C28), TPH-MO (C16-C36), methanol, and ethanol by <br /> USEPA Method 8015 <br /> • TPH-DRO (C10-C28), TPH-MO (C16-C36)with Silica Gel Clean-up <br /> 0 BTEX by USEPA Method 82608 <br /> • TBA, MTBE, ETBE, TAME, DIPE, 1,2-DCA, and EDB by USEPA Method 82608. <br /> e <br /> Purge water and equipment decontamination water generated during the sampling event was <br /> containerized for offsite disposal. Groundwater analytical results are included in Table 4. <br /> Analytical results for the groundwater samples collected by ARCADIS are included in <br /> Attachment G. <br /> \\CA5FP\Data\Aprojecl\EN\ACHEVRON1309075\6 Deliverables\Reports\DG Wells Assessment\Assessmenl Reporl_4741010950.doc 5 <br /> V <br />