Remedial Action Report Construction Phase

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5.5 Former Lui Property (Area 2) During pre-construction activities, a 1,500-gallon heating-oil UST was encountered beneath the northwest corner of the Liu building's basement (Figure 3). On October 16, 1997, Marion County decommissioned the UST by removal (Century West 1998a). Approximately 1,085 tons of petroleum impacted soil were removed in the vicinity of the Liu UST during decommissioning activities. Concentrations of petroleum hydrocarbons detected in confirmation soil samples collected from the excavation were less than the soil matrix cleanup levels except for one location adjacent to a sewer pipe along the western excavation boundary. During the construction phase, the sewer line was removed and approximately eight tons of diesel- impacted soil was excavated for off-site disposal. Groundwater was not observed in the Area 2 excavation. Confirmation soil sample 2-10-15.0 was collected from the bottom of the excavation and analyzed for NWTPH-Dx. Figure 7 shows the location of soil sample 2-10-15.0 and the extent of contaminated soil removed from Area 2 during the construction phase. No diesel range petroleum hydrocarbons were detected in confirmation soil sample 2-10-15.0 (Table 2). Although groundwater was not obser~~ed in the Area 2 excavation, dewatering was performed for construction purposes from Sump 5, located near Area 2. After pumping from the sump for at least 24 hours and allowing groundwater to recharge, a water sample labeled SW-Influent was collected from Sump 5 on May 27, 1999 for NWTPH-Dx and BTEX analysis. Figure 4 shows the location of Sump 5. Diesel was not detected in water sample SW-Influent collected from Sump 5 on May 27, 1999 (Table 15). BTEX concentrations in this sample were significantly below the applicable RBCA Tier I RBSLs (Table 15). 5.6 Former Chevron Property (Areas 6, 7, and 20) Area 6 During pre-construction remedial actions, approximately 3,800 tons of gasoline impacted soil were removed from Area 6, located in the southeast corner of the Courthouse Square property (Century West 1998c). The depth of the remedial eYCavation ranged between 15 and 20 feet below street grade. Analytical results for soil samples collected from Area 6 indicated that approximately 300 cubic yards of gasoline impacted soil was left in place in the southeast corner of the Chevron property. Construction Phase - Remedial Actions - 16 - 4080600127 Courthouse Squaze November 9, 1999