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Mmmn <br /> wo <br /> Chevron <br /> Chevron Pipe Line Company <br /> February 19, 1999 4000 Executive Parkway,Suite 400 <br /> San Ramon,CA 94583 <br /> P.O.Box 6059 <br /> San Ramon,CA 94583-0759 <br /> Mr. Michael Infurna, Jr. <br /> San Joaquin County Public Health Services—Environmental Health Division <br /> 304 E. Weber Avenue, Third Floor <br /> Stockton, California 95202 <br /> Laboratory Methods <br /> Surland Homes Property <br /> Tracy, California <br /> Dear Mr. Infurna: <br /> Per your request, Chevron Pipe Line Company (CPL) has prepared the following summary <br /> comparing the laboratory methods used for groundwater samples collected at the Surland Homes <br /> property versus those collected at the Dividend Property (specifically, monitoring wells, MW-13, <br /> MW-14, MW-15, MW-20, and MW-25; see attached Figure). <br /> The laboratory analyses performed on groundwater samples collected from monitoring wells <br /> MW-13, MW-14, MW-15, MW-20, and MW-25 at the Dividend Property were for Total <br /> Purgeable Petroleum Hydrocarbons (TPPH, C5 to C12carbon range)by EPA Method 8015M <br /> (extracted by EPA Method 5030), Total Extractable Petroleum Hydrocarbons (TEPH, Cato C36 <br /> carbon range)by EPA Method 8015M (extracted by EPA Method 3520), benzene,toluene, <br /> ethylbenzene, and xylenes (BTEX)by EPA Method 8020, and polynuclear aromatic <br /> hydrocarbons (PAHs) by EPA Method 8310. <br /> The laboratory analyses performed on groundwater samples collected at the Surland Homes <br /> Property (specifically from temporary monitoring wells TW-1 and TW-2)were for Total <br /> Petroleum Hydrocarbons as gasoline (TPHg, C,to C12 carbon range) by EPA Method 8015M <br /> (extracted by EPA Method 503013), Total Petroleum Hydrocarbons as diesel (TPHd, C1O to C24 <br /> carbon range) by EPA Method 8015M (extracted by EPA Method 3510C), BTEX by EPA <br /> Method 802113, and PAI-Is by EPA Method 8270 SIM. <br /> The analyses of water samples at the Dividend Property were performed prior to Geomatrix's <br /> March 19, 1997 "Technical Approach to Site Evaluation and Decision Making" (Consistent <br /> Approach). The analyses performed on water samples collected at the Surland Homes property <br /> were performed in accordance with the Consistent Approach. The analyses for gasoline and <br /> diesel range petroleum hydrocarbons at both sites are comparable; both used the same laboratory <br /> analytical methods over similar carbon ranges. While the TEPH analyses extended to the C36 <br /> carbon range and the TPHd analyses extended to the C24 carbon range, analytical results would <br />