ARCHIVED REPORTS XR0000428 - Laserfiche WebLink

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DISCUSSION: Total petroleum hydrocarbons as gasoline(TPHg)were reported in 5 of the 19 wells sampled this quarter(E-2 through E-4,E-8,and E-9) at concentrations ranging from 52 ppb (E-2)to 680 ppb(E-4) Benzene was reported in 4 of the 19 wells(E-3,E-4,E-9,and E-10)at concentrations ranging from 2 1 ppb(E-3)to 610 ppb(E-10) Methyl tert-butyl ether(MtBE) was reported in 6 of the 19 wells(E-4,E-6,E-8,E-9,E-10, and BHD-1) at concentrations ranging from 2 9 ppb(E-8)to 44,000 ppb(E-10) Chemical concentrations were generally consistent with historical data Groundwater elevations across the site increased by an average of 1 78 ft Groundwater flow was to the northeast-northwest at an approximate gradient of 0 002—0 004 ft/ft,which is generally consistent with historical data Attachment A contains historical SVE and recent AS system operational data Groundwater monitoring and sampling was coordinated with Chevron service station#94275,located north across Benjamin Holt Dr Attachment D contains Chevron groundwater elevation and analytical data 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 o Table 2-Groundwater Gradient Data C Figure 1 -Groundwater Elevation Contour Map o Figure 2-Groundwater Concentration Map o Attachment A-Remedial System Performance Evaluation o Attachment B -Field and Laboratory Procedures • Attachment C-Certified Laboratory Analytical Reports,Cham-of-Custody Documentation,and Field Data Sheets • Attachment D-Chevron Groundwater Elevation and Analytical Data cc Mr Bob Cochran,Chevron Products Company Ms Lori Duncan, SJCPHS Mr Mary Hartzell,California Regional Water Quality Control Board-Central Valley Region (RWQCB-CVR)