ARCHIVED REPORTS_XR0005733 - Laserfiche WebLink

Home Browse Search

a S E C O R DISCUSSION: Total petroleum hydrocarbons as gasoline (TPHg) were reported in three of the eleven monitoring wells sampled this quarter at concentrations of 130 ppb (MW-3), 590 ppb (DMW-2) and 1,900 ppb (MW-1) Benzene was reported in one of the eleven monitoring wells at a concentration of 150 ppb (MW-1) Methyl tert-butyl ether (MtBE), analyzed using EPA Method 8260B, was detected in eight of the eleven monitoring wells at concentrations ranging from 0 fit ppb (MW-9) to 99 ppb (DMW-3) DI-Isopropyl ether (DIPE) was reported in one well (MW-3) at 1 3 ppb 1,2-dichloroethane (1,2-DCA) was reported in five of the eleven monitoring wells at concentrations ranging from 1 0 ppb (MW-5)to 74 ppb (MW-3) MW-2 was not sampled because the well was dry Chemical concentrations were generally consistent with historical data Additionally, domestic well WSW and well DW-2 were sampled for TPHg, BTEX, MtBE, and other fuel oxygenates/additives, all of which were reported as non-detectable above the method reporting limits The direction of groundwater flow within shallow wells (MW-1 through MW-10) was Northwest, at a gradient of 0 003 fUft The direction of groundwater flow within d DMW-1 through DMW-3) was to the north, at a gradient o 01 n wes southest at a radient of 0 04 ft/ft Groundwater elevations in shallow monitoring wells MWA through MW-10 decreased by an average of 1 63 ft, with the exception of MW-1, for which the elevation increased by 3 24 ft SECOR is performing granulated activated carbon treatment on well DW-1 Influent and effluent water samples are taken monthly and reported under separate cover in monthly performance summaries DW- 2 and the onsite water supply welt (WSW) are Incorporated Into the quarterly monitoring and reporting Analytical data from DW-2 is included in Tables 4 and 5 Certified laboratory analytical data are Included in Attachment B 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 • Table 4—Domestic Well Analytical Data • Table 5—Domestic Well Fuel Oxygenates and Nitrate/Nitrite Analytical Data • Figure 1 —Shallow Groundwater Elevation Contour Map • Figure 2—Deep Groundwater Elevation Contour Map • Figure 3 - Groundwater Chemical Concentration Map • Attachment A- Field and Laboratory Procedures • Attachment B-Certified Laboratory Analytical Reports, Chain-of-Custody Documentation, and Field Data Sheets cc Mr James Barton, Regional Water Quality Control Board - Central Valley Region (RWQCB-CVR) Ms Lori Duncan, SJCPHS Ms Madeline Scannavino, 5463 Cherokee Rd , Stockton, CA 95205 11ARC01059SQMRsM0M3QMR03 doc