ARCHIVED REPORTS_SECOND SEMIANNUAL 2018 GROUNDWATER MONITORING REPORT

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JACOBS® Second Semiannual and 2018 Annual Groundwater Monitoring Report . 1.2.1 Site Investigation Activities SFPP completed significant investigation activities to characterize the subsurface physical characteristics, the nature and extent of hydrocarbon-affected media, and the fate-and-transport mechanisms at the site. These investigations showed that dissolved-phase hydrocarbons and separate nonaqueous-phase hydrocarbons (NAPH)were present in the vicinity of the former SFPP pipeline and migrated southeast beneath Whiskey Slough Road. Beginning in 1987 after the spill and emergency response activities, numerous investigations were performed that have defined the horizontal and vertical extents of these hydrocarbons. 41 These investigations included the following activities: . • Drilling and logging numerous soil borings . • Performing cone penetrometer testing and ultraviolet-induced fluorescence testing, both tests in situ • Installing 20 monitoring wells (13 by SFPP and 7 by Arcady Oil Company) . • Collecting and analyzing numerous soil gas, soil, and groundwater samples from temporary borings and permanent wells • Monitoring the groundwater monitoring well network since 1992 on a quarterly or semiannual basis 1.2.2 Interim Site Remediation Activities . SFPP has completed significant interim remedial activities to contain and remove hydrocarbons from the subsurface, including the following: . • NAPH Removal. Removal (bailing) of NAPH from wells was initiated in the 1990s. . • Groundwater Extraction and Treatment System (GWETS). A GWETS was constructed beginning . in 1995 and was operational between 1997 and 2004, at which time it was shut down for a 3-year bioremediation pilot study. During operation, groundwater was extracted from three extraction wells . (RW-1, RW-3, and N-17); treated with an oil-water separator, air stripper, liquid-phase and vapor- phase granular activated carbon, aeration, and temporary retention; and discharged under a National Pollutant Discharge Elimination System (NPDES) permit to Trapper Slough. The aboveground . portions of the groundwater treatment system were removed from the site in October 2005 in response to positive results after the initial year of the 3-year bioremediation pilot study. • Soil Vapor Extraction and Treatment System (SVETS). A SVETS was constructed beginning M in 1999 and was operated from 2000 to 2001. A pilot test was performed at one soil vapor extraction (SVE) well (VEW-1) in 1998. During operations, soil vapor was extracted from nine extraction wells (VEW-2 through VEW-10), treated with three internal combustion (IC) engines, and discharged under a permit with the San Joaquin Valley Unified Air Pollution Control District. • Multiphase Extraction (MPX). Pilot testing of the SVETS to conduct MPX of soil vapor and shallow • groundwater was performed from 2002 through 2004, at which time the system was shut down for the 3-year bioremediation pilot study. MPX was conducted to enhance removal of hydrocarbons within . the smear zone at the water table. During MPX pilot testing, soil vapor, groundwater, and NAPH were extracted using a single IC engine from four extraction wells (SVE-2 through SVE-5). Soil vapor was treated with the IC engine and discharged under a permit issued by the San Joaquin Valley Unified Air Pollution Control District. Water and NAPH were treated by the GWETS. 1.2.3 Current Site Remediation Activities The following remediation activities are currently being implemented to contain and remove hydrocarbons from the subsurface. . i r AX1015181035SCO