ARCHIVED REPORTS XR0001554 - Laserfiche WebLink

Home Browse Search

Gt Mr Michael Infurna Page 2 of 5 • APPro3umately 250 cubic yards of contaminated soil was excavated on June 16 and June 30, 1994 Confirmation soil samples and groundwater samples were collected from within the excavation Other than low levels of MTBE, no petroleum hydrocarbon analytes were detected in the confirmation soil samples, however, elevated levels were detected in the groundwater On July 7, 1999, approximately 7,000 gallons of contaminated groundwater was pumped from the excavation pit and transported to the Stockton Wastewater Disposal Facility for disposal Between April 15 and July 7, 1999 a total of 414 cubic yards of contaminated soil generated during the UST removal and excavation activities were trucked to Forward Landfill for disposal Monitoring wells MW1, MW2, and MW3 were installed at the site on November 15 and 19, 1999 Soil samples collected from boring MWl and MW2 did not contain any detectable amounts of petroleum hydrocarbons or gasoline oxygenate additives In boring MW3, elevated levels of TPHd, TPHg, ethylbenzene, and xylenes were detected, however, no MTBE or gasoline oxygenate additives were found above laboratory method detection hmrts No petroleum hydrocarbons or gasoline oxygenate additives were detected in the initial groundwater collected from wells MW 1 and MW2, however, elevated levels of TPHd, TPHg, MTBE, tert-butanol (TBA) and some BTEX constituents were found in well MW3 Groundwater monitoring and sampling has occurred at the site on a quarterly basis since well installation Cumulative analytical data indicate that no contaminants of concern have been detected in wells MWl or MW2 since sampling began in those wells In well MW3, a general trend of decreasing contaminant concentrations has been apparent Groundwater contamination in the vicinity of well MW3 appears to be very localized However, until the two most recent quarterly monitoring events, groundwater flow direction was variable, and often to the northwest or southeast where no monitoring wells exist EHD directed that this data gap be remedied by the installation of additional wells Cumulative soil analytical data are summarized in Table 1 Historical groundwater analytical data are summarized in Table 2 i On May 1, 2002 Ground Zero's Workplan for Additional Subsurface Investigation was submitted to EHD for approval The Workplan proposed the installation of two groundwater monitoring wells, one to the northwest and one to the southeast of the former tankpit The Workplan was approved by EHD in a letter dated May 30, 2002 The work described herein was conducted in accordance with the Workplan and the modifications thereof requested in the EHD letter PROCEDURES Permitting and Protocols Prior to initiating fieldwork, well installation permits were obtained from San Joaquin County EI-ID All fieldwork was performed in accordance with the Ground Zero's Site Safety Plan and Quality Assurance/Quality Control Plan on file with EHD All work conducted at the site was performed . under the supervision of field geologist Sean Garvey and project manager Greg Stahl, a California Registered Geologist G WataNGROUNDZEMOOLSEY c1HMepotts\WELLRPT_MW4 MW5 doc