ARCHIVED REPORTS XR0002743 - Laserfiche WebLink

Home Browse Search

S E C O R DISCUSSION: Total petroleum hydrocarbons as gasoline (TPHg) were reported in five of the sixteen wells sampled this quarter at concentrations ranging from 760 ppb (MW-2) to 37,000 ppb (EW-1) Benzene was reported in two of the sixteen wells at concentrations of 1,500 ppb (MW-4) and 1,100 ppb (EW-1) Methyl tert-butyl ether (MtBE), analyzed using EPA Method 82606, was reported in eleven of the sixteen wells at concentrations ranging from 0 76 ppb (MW-3) to 32,000 ppb (MW-6) 1,2-Dichloroethane (1,2-DCA) was reported in seven of the wells at concentrations ranging from 1 3 ppb (MW-9) to 170 ppb (MW-4) Di- Isopropyl ether (DIPE) was reported in one well (DMW-1) at a concentration of 5 0 ppb Tert-butyl alcohol (TBA), tert-amyl methyl ether (TAME), ethylene dibromide (EDB), and ethyl tert butyl ether (ETBE) were not detected in any wells this quarter Chemical concentrations were generally consistent with historical data Groundwater flow within the shallow water-bearing zone was to the northeast at an approximate gradient of 0 007 ft/ft Groundwater flow within the deeper water-bearing zone was to the northeast at an approximate gradient of 0 011 ft/ft The groundwater flow direction and hydraulic gradient reported for the shallow and deeper water-bearing zones during the fourth quarter 2003 are also consistent with historical data A remedial performance summary of site remediation activities is included in Attachment A Field and laboratory procedures are included in Attachment B Certified laboratory analytical reports, chain-of-custody documentation, and field data sheets are included as Attachment C Groundwater monitoring and sampling was coordinated with activities performed at former 76 Service Station No 4409, located northeast of the site Attachment D contains a report prepared by TRC, which includes groundwater elevations and analytical data for groundwater monitoring wells at the former 76 Service Station site �I This report presents our understanding of existing conditions at the subject site The conclusions contained herein are based on the analytical results, and professional judgment in accordance with current standards of professional practice, no other warranty is expressed or implied SECOR assumes no responsibility for exploratory borings or data reported by other consultants or contractors ATTACHMENTS: • Table 1 —Groundwater Elevation and Analytical Data • Table 2--Fuel Oxygenates Analytical Data • Table 3—Groundwater Gradient Data • Figure 1 —Groundwater Elevation Contour Map—Shallow Water Bearing Zone • Figure 2—Groundwater Elevation Contour Map—Deep Water Bearing Zone • Figure 3—Groundwater Chemical Concentration Map • Figure 4—MtBE Isoconcentration Contour Map—Shallow Water Bearing Zone • Figure 5—MtBE Isoconcentration Contour Map—Deep Water Bearing Zone • Attachment A--Remedial System Performance Evaluation • Attachment B—Field and Laboratory Procedures • Attachment C—Certified Laboratory Analytical Report, Chain-of-Custody Documentation, and Field Data Sheets (ARCO) • Attachment D—Groundwater Monitoring and Sampling Report for Former 76 Service Station No 4409 (TRC) cc Mr James Barton, Regional Water Quality Control Board - Central Valley Region (RWQCB-CVA) Ms Lori Duncan, SJCPHS Vern Elrath, URS Corporation i I I\ARC0149321QMRs1200314QMR03 doc