Remedial Action Report Construction Phase

Home Browse Search

applicable RBCA Tier I RBSLs. No EDB or EDC was detected in soil sample 22-10-15.5 (Table 7). Lead was detected at a concentration of 6.63 mg/kg in soil sample 22-10-15.5, significantly below the RBCA Tier I RBSL of 2,000 mg/kg (Table 7). Two dewatering sumps (Sumps 2 and 6) were installed during Area 22 excavation. After pumping from the sumps for at least 24 hours and allowing groundwater recharge, water samples were collected from the sumps to assess groundwater quality. On May 4, 1999 and May 11, 1999, water samples both labeled SW-Influent were collected from Sump 2 and analyzed for NWTPH-Dx and BTEX. On June 14, 1999, a water sample labeled SW-Influent was collected from Sump 6 and analyzed for NWTPH-Dx and BTEX. Figure 4 shows the location of the Sumps. Diesel was detected at a concentration of 0.59 milligrams per liter (mg/L) in the water sample (SW- Influent) collected from Sump 2 on May 4, 1999 (Table 15). BTEX concentrations in this sample were significantly below the applicable RBCA Tier I RBSLs. Diesel and BTEX were not detected in the Influent water sample collected from Sump 2 on May 11, 1999 (Table 15). Diesel was detected at a concentration of 0.396 mg/L in the water sample (SW-Influent) collected from Sump 6 on June 14, 1999 (Table 15). BTEX concentrations in this sample were significantly below the applicable RBCA Tier I RBSLs (Table 15). 5.3 Former Goodman Property (Area 19) During construction activities on April 4, 1999, excavation was performed in the location of a former heating-oil UST in the northeast corner of the former Goodman property (Area 19). Based on information included in the ESA, the UST was decommissioned by removal between 1991 and 1993 (Century West 1996c). Soil sample 19-1-10.5 was collected from contaminated soil observed in the excavation and analyzed for NWTPH-HCID to evaluate disposal options. Based on the analytical results, which indicated diesel at a concentration of 6,800 mg/kg, approximately 155 tons of diesel- impacted soil were excavated from Area 19 for off-site disposal. Groundwater was not observed in the excavation. Confirmation soil samples 19-2 through 19-5 were collected from the bottom of the excavation and analyzed for NWTPH-Dx. Figure 7 shows the location of the samples and the extent of contaminated soil removed from Area 19. Diesel was detected at a concentration of 120 mg/kg in confirnlation soil sample 19-2-9.5, below the 500 mg/kg soil matrix cleanup level (Table 8). Petroleum hydrocarbons were not detected in the three other confirmation soil samples. Construction Phase - Remedial Ac[ions - I4 - 4080600127 Courthouse Square November 9, 1999