Surfactant-enhanced subsurface remediation of DNAPLs at the former naval air station alameda, california

摘要

A surfactant enhanced subsurface remediation (SESR) field demonstration was conducted at Alameda Point (formerly Naval Air Station Alameda) to demonstrate enhanced dense non-aqueous phase liquid (DNAPL) removal at Site 5. The overall project goal was to remove 95 percent of the trapped DNAPL from fill sand within a 20' x 20' x 5' volume. The DNAPL at the site consists primarily of 1,1,1 Trichloroethane (TCA), Trichloroethylene (TCE) 1,1 Dichloroethylene (DEC), and 1, 1 Dichloroethane (DCA). The surfactant solution selected for field application consisted for hexadecyl diphenyloxide disulfonate, (C16-DPDS or Dowfax 8390), sodium dihexyl sulfosuccinate (AMA-80), calcium chloride, and sodium chloride. Six pore volumes of surfactant solution were flushed through the test area over a 15-day period using four injection wells and four recovery wells and was followed by 9 days of water flooding. A macro porous polymer (MPP; Akzo Nobel) liquid-liquid extraction system was utilized to remove chlorinated solvents from the recovered surfactant solution. Surfactants were then concentrated using micellar enhanced ultrafiltration (MEUF) and re-injected into the test cell. Post-test soil coring results (8 soil borings and 18 samples) showed the chlorinated solvent concentrations to be non-detectable within he fill sand after surfactant flushing. Pre-and post-partitioning interwell tracer tests (PITT) were also conducted to evaluate NAPL removal. These results showed over 97 percent of DNAPL mass removal from the test cell area. Over 320 kg of Trichloroethane and Trichloroethene were removed from the cell during the 24-day period.