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GEDMATRIX <br /> 2.0 FIELD PROCEDURES <br /> The following sections describe the field methods used by Geomatnx to collect groundwater <br /> samples at UST Site No 3 <br />' Groundwater samples were collected from the three previously existing (MW3-1, MW3-2, and <br />' MW3-3) and three new (MW3-4, MW3-5, and MW3-6) groundwater monitoring wells by <br /> Geomatnx personnel on February 20, 2003 Depth to groundwater was measured in all the wells <br /> before purging any of the wells Prior to sampling each well, the presence of separate-phase <br />' petroleum hydrocarbons (PHC) was assessed using an interface probe At least three casing <br /> volumes of water were purged from each well using a clean submersible pump The purge pump <br />' was decontaminated before purging each well To prevent crass-contamination, the well <br /> sampling was sequenced so that the wells with the least amount of anticipated impact were <br />' sampled first The wells were sampled in the following order MW34, MW3-5, MW3-6, <br /> MW3-1, MW3-3, and MW3-2 <br />' Field parameters (i e , electric conductivity, pH, oxygen reduction potential, dissolved oxygen, <br /> and temperature) were measured during well purging and recorded on field data sheets <br /> (Appendix A) Groundwater samples were collected after three casing volumes of groundwater <br /> were purged from each well and field parameters had stabilized Disposable bailers were used to <br /> collect the groundwater samples for laboratory analysis of volatile organic compounds, and the <br /> submersible pump was used to collect the groundwater samples for inorganic compounds <br /> 1 Groundwater samples were preserved and transported under chain-of-custody (Appendix B) <br /> procedures to Agriculture and Priority Pollutants Laboratories, Inc (APPL), of Fresno, a <br />' California-certified laboratory, for analyses The groundwater samples from MW3-1, MW3-2, <br /> and MW3-3 were analyzed for total petroleum hydrocarbons quantified as gasoline (TPHg) using <br />' U S Environmental Protection Agency (EPA) Method 8015, and benzene, toluene, <br /> ethylbenzene, and xylenes (BTT-7X) using U S EPA Method 8260B The groundwater samples <br />' from MW3-4, MW3-5, and MW3-6 were analyzed for TPHg using U S EPA Method 8015, <br /> BTEX and oxygenates using U S EPA Method 8260B, and dissolved lead using U S EPA <br /> Method 6010, as requested by the SJCDEH The tested oxygenates were diisopropyl ether <br />' (DIPE), ethyl tert butyl ether(EtBE), methyl tert butyl ether(MtBE), and tert amyl methyl ether <br /> MME) Additional samples were collected from some of the groundwater monitoring wells and <br />' analyzed for parameters to evaluate intrinsic bioremediation on the site Intrinsic bioremediation <br /> is discussed in the Results of Additional Assessment and Remediation Evaluation of Petroleum <br />' Hydrocarbons in Groundwater (Geomatnx, 2003) <br /> I 1PROjEcr( Ws16437 00016437-06 doe 2 <br /> 1 <br />