This study determined: (a) waste constituents remaining at long-term hazardous waste land treatment (HWLT) sites, and (b) the potential for subsequent degradation and migration of these constituents. Soils from six depths from random test pits at two oil refinery sites and a wood preserving site were evaluated for specific metals and organics. In surface soils, concentrations of organics and metals were greater than in background soils. At depths below 24-30” (60-76 cm) at the HWLT sites, PAH concentrations were below detection limits and the freon-extractable concentrations were at background. Chromium and nickel at depths below 24” (60 cm) appeared greater than background soil concentrations, but not copper, lead, and zinc concentrations.
Organics in TCLP extracts of site soils indicated no PAH compounds were extracted from either weathered or non-weathered soils. In most of the site soil samples, metals in the TCLP extracts were close to or below detection limits of 0.1 mg/L.
Aerobic and anaerobic microcosm studies indicated no statistically significant degradation of the PAH and freon extractables in the surface soil samples over eight months, suggesting very slow degradation of the accumulated organics following closure of an HWLT site.