ARCHIVED REPORTS_FIRST SEMIANNUAL AND 2014 ANNUAL GROUNDWATER MONITORING REPORT

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1.INTRODUCTION Hydrocarbon residuals from the February 1986 pipeline release are present in subsurface soils and groundwater at the Site. A comprehensive summary and analysis of historical site investigation and interim remediation activities addressing these hydrocarbons is presented in the Final Site Characterization Report (CH2M HILL, 2002). A summary of these historical and current site remediation activities is provided below. 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 (NAPHs) 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. These investigations included the following activities: • Drilling and logging numerous soil borings • Performing cone penetrometer testing (CPT) and ultraviolet-induced fluorescence (UVIF) testing,both tests in situ • Installing 20 monitoring wells (7 by Arcady and 13 by SFPP) • 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 completed significant interim remedial activities to contain and remove hydrocarbons from the subsurface. The interim remediation activities have included the following: • NAPH Removal. Removing (bailing) NAPH from wells in the 1990s. • Groundwater Extraction and Treatment System. A groundwater extraction and treatment system (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 operations, groundwater was extracted from three extraction wells (RW-1, RW-3, and N-17); treated with an oil/water separator, air stripper, liquid and vapor-phase granular-activated carbon(GAC), aeration, and temporary retention; and discharged under a National Pollution 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 the positive results after the initial year of the 3-year bioremediation pilot study. • Soil Vapor Extraction and Treatment System. A soil vapor extraction and treatment system (SVETS), which was constructed beginning in 1999 and was operated from 2000 to 2001. A pilot test was performed for one soil vapor extraction (SVE) well (VEW-1) in 1-2 ESO41514081714SCO/HOLT_1SA14_TEXT_FINAL