Demonstrating Leaching Reductions of NAPL-Impacted Soils Treated with Stabilization/Solidification Using Modified EPA Method 1315

Abstract

A phased stabilization/solidification (S/S) treatability study was performed on nonaqueous phase liquid (NAPL)–impacted soils at the Quanta Resources Superfund site, where naphthalene was the key constituent of concern (COC) from a mass perspective. Conventional synthetic precipitation leaching procedure (SPLP) testing was used to characterize the baseline leaching of the untreated soil. SPLP and two semi-dynamic leaching (SDL) methods [American Nuclear Society (ANS)/American National Standards Institute (ANSI) 16.1 and EPA Method 1315 modified for organics] were used to assess leaching reduction of the S/S treatments to demonstrate a 90% reduction in total COC leaching, as required by the Record of Decision. As expected, SPLP testing of treated samples produced virtually no change in leaching behavior, whereas a 5-day ANS/ANSI 16.1 was effective in a screening mode to identify successful mix designs for long-term (67-day) testing via EPA Method 1315M. Total pozzolan doses of 8% by weight or greater satisfied the UCS and hydraulic conductivity criteria, and leaching reductions of 90% or more were realized for the majority of the COCs per EPA Method 1315M.