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S E C 0 R <br /> Third Quarter 2004, Groundwater Monitoring Report <br /> November 10, 2004 <br /> • Page 2 , <br /> Groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg), <br /> benzene, toluene, ethylbenzene, and xylenes (BTEX), and the fuel oxygenates methyl tertiary butyl <br /> ether (MtBE), ethyl-tertiary-butyl-ether (EtBE), di-isopropyl ether (DIPE), tertiary-amyl-methyl-ether <br /> (TAME), tertiary-butyl-alcohol (TBA), 1,2 dichloroethane (1,2 DCA), and 1,2 dibromoethane (EDB). <br /> A summary of laboratory data is listed below. <br /> CHEVRON <br /> Number of Detections <br /> above the MDL of the 8 Minimum Maximum <br /> Constituents Total Samples Concentration in pg/L(Well ID) Concentration In pg1L(Well ID) <br /> TPHg 4 80(MW-6) 4,200(MW-5) <br /> Benzene 2 2(MW-2) 16(MW-5) <br /> MtBE 7 3(MW-4) 630(MW-3) <br /> Ethylbenzene 2 20(MW-2) 170(MW-5) <br /> Total xylenes 2 28(MW-2) 98(MW-5) <br /> Definitions: <br /> MDL=Method Detection Limit <br /> pg/L=Micrograms per Liter <br /> ND =Not Detected <br /> ARCO <br /> Number of Detections Minimum Maximum <br /> Constituents above the MDL of the 13 Concentration in Vg/L(Well ID) Concentration in pg/L(Well ID) <br /> Total Samples <br /> TPHg 6 50(E-9) 14,000(E-10) <br /> Benzene 5 3(BDH-1) 470(E-10) <br /> MtBE 8 .60(E-2) 3,000(E-10) <br /> Ethylbenzene 3 .83(E-4) 330(E-10) <br /> Total xylenes 3 1 (BHD-1) 1,300(E-10) <br /> Definitions: <br /> MDL=Method Detection Limit <br /> pg/L=Micrograms per Liter <br /> QUARTERLY RESULTS SUMMARY (CHEVRON &ARCO) <br /> Groundwater flow across both sites was to the north-northeast at an approximate hydraulic gradient <br /> ranging from 0.001 to 0.004 foot per foot (ft/ft). Groundwater gradient has typically been to the north <br /> across both sites. A groundwater elevation contour map of the two sites is presented as Figure 2. <br /> Groundwater concentrations for both sites are summarized for TPHg, benzene, and MtBE in Figure <br /> 3. CHEVRON's and ARCO's groundwater elevation and analytical data are summarized in Tables 1 <br /> and 2, respectively. CHEVRON's and ARCO's groundwater analytical data for oxygenated <br /> compounds is presented in Tables 3 and 4, respectively. Historical groundwater gradient data is <br /> presented in Table 5. Field and laboratory procedures are presented in Attachment A. CHEVRON's <br /> laboratory analytical results, chain-of-custody documents, and field data sheets are provided as <br /> I:1Chevron1942751Periodic Monitoring\Q M R1200413Q04.doc <br />