ARCHIVED REPORTS_XR0010585 - Laserfiche WebLink

Home Browse Search

23 July 2002 AGE-NC Project No 97-0249 Page 2 of 8 within the Guard-Devnes-Riblancho (GDR) association The GDR soils are located within basin rims along the eastern edge of the Sacramento-San Joaquin Delta area, and generally consist of poorly drained, fine to coarse textured soils The GDR soils generally formed in alluvium from mixed rock sources 2 2 UNDERGROUND STORAGE TANK REMOVAL In October 1998, three gasoline USTs, one diesel UST and associated fuel dispensers and product piping were removed from the site Laboratory analysis of soil samples collected beneath the former UST areas detected total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d, respectively) at concentrations up to 12,000 mg/kg (milligrams per kilogram) TPH-d, benzene, toluene, ethylbenzene and xylene compounds (BTEX) at concentrations as high as 330 mg/kg xylenes, and methyl tertiary butyl ether (MTBE) at concentrations up to 6 2 mg/kg Analytical results of soil samples collected during tank removal activities are summarized in Table 1 • 23 PREVIOUS SUBSURFACE INVESTIGATION The following is a brief summary of site assessment activities September 1997 and August 1998 -Nine soil borings (P1 through P9)were advanced at the site to characterize and assess the lateral and vertical extent of Impacted soil TPH-g was detected in analyzed samples at concentrations up to 3,200 mg/kg, TPH-d was detected at concentrations as high as 7,100 mg/kg, and BTEX compounds were detected at concentrations up to 180 mg/kg TPH-g was detected In grab water samples collected from P-1 through P-4 at concentrations as high as 120,000 µg/1 (P-3), TPH-d at concentrations as high as 530,000 µg/l (P-4) and BTEX compounds at concentrations as high as 19,000 gg/l toluene(P-3) Analytical results of soil and grab water samples are summarized in Tables 2 and 3, respectively Results of the September 1997 investigation were reported in the Preliminary Investigation and Evaluation Report(PIER) dated 05 November 1997, results of the August 1998 investigation were reported in Site Assessment Report,dated 27 October 1998 • March 1999 - Six ground water monitoring wells (MW-1 through MW-6) were installed at the site as part of site assessment activities TPH-g and TPH-d were detected in analyzed soil samples at concentrations as high as 920 mg/kg, BTEX compounds were detected at concentrations as high as 40 mg/kg xylenes, and MTBE was detected at a concentration of 0 0063 mg/kg(in one soil sample from MW-4) TPH-g was detected in initial ground water . samples collected from MW-1 through MW-6 at concentrations as high as 24,000 gg/l, TPH-d at concentrations as high as 6,400 gg/l, BTEX compounds at concentrations as high Advanced GeoEnvironmental,Inc