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ARCADIS Ms. Lori Duncan <br /> March 20, 2009 <br /> detected in one to two soil samples at concentrations below their respective ESLs. <br /> 1, 2-DCA was detected in three soil samples SB-2-S-60 (0.005 mg/kg), SB-2-S-70 <br /> (0.060 mg/kg)and SB-2-S-80(0.18 mg/kg), all at concentrations above the ESL. <br /> Soil analytical data are presented in Table 1. The analytical report and chain-of-. <br /> custody documentation are presented in Attachment 4. <br /> Temporary Monitoring Well and Groundwater Sampling, <br /> The temporary monitoring well was constructed of 2 inch Schedule 40 PVC casing <br /> with 5 feet(115 feet bgs to 120jeet bgs)of 0.010 slotted PVC well screen. A 2/12 <br /> sand filter pack was placed around the well screen from the bottom of the borehole to <br /> approximately 2 feet above the top of the screen interval. The water table was <br /> encountered at approximately 115 feet bgs. Prior to groundwater sampling, three <br /> casing volumes of water was purged from the temporary well with a peristaltic pump <br /> to remove sediments accumulated during drilling activities. During the purge cycle, <br /> groundwater field parameter measurements consisting of specific conductance, pH, <br /> turbidity, color, odor, salinity, dissolved oxygen, oxygen reduction potential, and <br /> temperature were measured using a water quality meter. Groundwater samples were <br /> collected from the temporary well using a Teflon bailer, then transferred to the <br /> appropriate laboratory-supplied sample containers. <br /> Groundwater Analytical Data <br /> Following collection, the groundwater sample was packed on ice, cooled to <br /> approximately 4 degrees centigrade, and shipped, under appropriate chain-of=custody <br /> protocols, to Lancaster for analysis. The analytical reports and chains-of-custody <br /> documentation are presented in Attachment 5. Groundwater samples were analyzed. <br /> for the presence of the following constituents: <br /> • TPH-GRO (C6-C12), TPH-DRO (C10-C28), TPH-MO (Cls-C36), and methanol <br /> by USEPA Method 8015 <br /> • BTEX by USEPA Method 8260 <br /> • TBA, MTBE, ETRE, TAME, DIPE, 1,2-DCA, EDB, and ethanol by USEPA <br /> Method 8260 <br /> C <br /> Page: <br /> lla=cri"slo8icedalalSacremento-CA1EMACHEVRONW907516 DeliverableslReponsukesessment AddendumlTezt1309075 Site Assessment Addendum Report282910950.doc 5/7 <br />