ARCHIVED REPORTS_XR0004398 - Laserfiche WebLink

Home Browse Search

' Royal Oak Savings & Loan SID N. Main Street, Manteca, California May 29, 1993 ' final Report and Request for Site Closure Page 3 1 ' Monitoring well number 8 was installed in May 1991 by request of the San Joaquin County Environmental Health Department Their request was made as a result of a ground water gradient change and the Health Department's belief ' that ground water contamination could have migrated to the Northeast. MW-8 has been none detected since installation and soil samples taken during the installation of the well were also none detected ' In the July, 1991 sampling round all wells (MW-2, MW-4, MW-5, MW-6, MW-7 and MW-8) showed "ND" for BTXE and gasoline In October and November of 1991, MW-2 and MW-7 revealed low levels of BTX or E compounds The January, 1992 sampling showed low levels of Benzene and Xylene in MW-2 In the April and July, 1992 samplings, MW-2, MW-6 and ' MW-7 were tested All three (3) wells showed "ND" levels for BTXE and gasoline ' WHF requested site closure in July 1992 The request was denied by the San Joaquin County Environmental Health Department based upon the sporadic '. findings of contaminants in MW-2 and MW-7 Subsequent discussions with the County revealed their belief that the soils left in place at the corner and the contamination found in the well boring of well 7 was the probable cause of the ' sporadic analytical results As a result of those discussions WHF proposed to install a soil gas vapor extraction system using the existing MW-2 as the extraction well, and did so after approval by the Health Department and the San ' Joaquin Valley Air Management District The system was installed in September of 1992 The system included a vacuum pump that was plumnea to ' a series of carbon drums The progress of the treatment was monitored using a portable Photo Ionization ' Detector per the requirements of the Air District A log of the results is included in this report Zero levels (less than 1 PPM) were measured on December 31, 1992 The system continued to operate for 60 more days before ' it was shut off All of the water sampling events since July 1992 sampling event have been none detected The most recent event was in April of 1993, the results of which, along with the chain of custody documentation, are included in this report. Gradient maps, other pertinent maps, diagrams and a summary of the last 24 months of laboratory data are also included in this report