ARCHIVED REPORTS_CLEANUP PLAN - Laserfiche WebLink

Home Browse Search

S E C ® f - - -- - - ' Cleanup Plan October 27, 2003 Page 5 20, and MW-21). Wells MW-14 through MW-16 were used for separate phase hydrocarbon ' (SPH) recovery and wells MW-18 and MW-19 were used for hydraulic containment (PEG, 1995). ■ In August of 1993, Geraghty & Miller, Inc. (G&M) performed a site assessment. Twenty soil ' borings were drilled in the farm field adjacent to the site. The results of groundwater samples collected from all 20 borings indicated total petroleum hydrocarbons as diesel (TPHd), total petroleum hydrocarbons as gasoline (TPHg), benzene and toluene concentrations were all non-detect(PEG, 1995). ■ In January of 1994, a groundwater remediation system was installed at the site for SPH recovery and hydraulic containment. The remedial system was initiated in February of 1994 and continued until February of 1996. During this time period, groundwater was extracted from wells, MW-18 and MW-19 (for hydraulic containment of groundwater), and SPH was recovered from wells, MW-14, MW-15, and MW-16 (PEG, 1995). ■ In June 1994, Touchtone Development observed the removal of one 10,000-gallon double ' walled fiberglass UST, pump island, and associated piping from the former Keylock Terminal Area. Two soil samples were collected from the former pump island area. Groundwater was observed in the tank excavation at approximately 8 feet bgs. (PEG, 1995). • In May 1995, Pacific Environmental Group submitted a Problem Assessment Report (PEG, 1995). The principal findings of the PAR are listed below: ' 1. The lateral and vertical extent of dissolved hydrocarbons in the lower water bearing zones was adequately defined. 2. Continued operation of the containment system, including the pumping of ' groundwater from the extraction wells maintained the shallow groundwater plume on site. 3. Continued SPH recovery and extraction of dissolved-phase hydrocarbons from three I ' wells within the SPH plume on site reduced hydrocarbon mass in groundwater. • On March 25, 1996, a dual extraction system (DE) system began continuous operation. The ' DE system was comprised of 14 DE wells (MW-1, MW-2, MW-7, MW-8, MW-14, MW-15, MW-16, and DE-1 through DE-7), a water knockout tank, an oil/water separator, four granular activated carbon vessels arranged in series, and a thermal oxidizer. In May of 1997, site data suggested the onsite SPH plume had been substantially diminished by the ' DE system. In addition, groundwater influent concentrations of TPHd had declined from 69,000 micrograms per liter (Ng/L) to 5,300 and influent vapor concentrations had declined from 300 parts per million by volume (ppmv) to 21 ppmv (SECOR, 1997). The DE system was shut down in June of 1997. Temporary shutdown of the DE system was approved by Ms. Gail Wiggett of the RWQCB during a meeting on June 2, 1997. ' From September of 2001 through April of 2002, SECOR conducted a six-month ISO-GEN TM pilot test/feasibility study for groundwater treatment. The pilot test included the installation of . six four-inch test wells (TW-1 through TW-6) and nine two-inch ISO-GEN TM monitoring wells ' (MW-24A through MW-32A). The groundwater monitoring wells and ISO-GENTm remediation I:\Chevron\1001621\REPORTS\2003\2003-Cleanup Plan\Cleanup Plan.doc