title: Impact of in situ chemical oxidation on contaminant mass discharge: linking source-zone and plume-scale characterizations of remediation performance.
abstract: A large-scale permanganate-based in situ chemical oxidation (ISCO) effort has been conducted over the past ten years at a federal Superfund site in Tucson, AZ, for which trichloroethene (TCE) is the primary contaminant of concern. Remediation performance was assessed by examining the impact of treatment on contaminant mass discharge, an approach that has been used for only a very few prior ISCO projects. Contaminant mass discharge tests were conducted before and after permanganate injection to measure the impact at the source-zone scale. The results indicate that ISCO caused a significant reduction in mass discharge (approximately 75%). The standard approach of characterizing discharge at the source-zone scale was supplemented with additional characterization at the plume scale, which was evaluated by examining the change in contaminant mass discharge associated with the pump-and-treat system. The integrated contaminant mass discharge decreased by approximately 70%, consistent with the source-zone-scale measurements. The integrated mass discharge rebounded from 0.1 to 0.2 kg/d within one year after cessation of permanganate injections, after which it has been stable for several years. Collection of the integrated contaminant mass discharge data throughout the ISCO treatment period provided a high-resolution, real-time analysis of the site-wide impact of ISCO, thereby linking source-zone remediation to impacts on overall risk. The results indicate that ISCO was successful in reducing contaminant mass discharge at this site, which comprises a highly heterogeneous subsurface environment. Analysis of TCE sediment concentration data for core material collected before and after ISCO supports the hypothesis that the remaining mass discharge is associated in part with poorly accessible contaminant mass residing within lower-permeability zones.
authors: School of Earth and Environmental Sciences, University of Arizona, Tucson, Arizona, USA. brusseau@email.arizona.edu
authors: M L
authors: ML
authors: Brusseau
authors: K C
authors: KC
authors: Carroll
authors: T
authors: T
authors: Allen
authors: J
authors: J
authors: Baker
authors: W
authors: W
authors: Diguiseppi
authors: J
authors: J
authors: Hatton
authors: C
authors: C
authors: Morrison
authors: A
authors: A
authors: Russo
authors: J
authors: J
authors: Berkompas
references: J Hazard Mater. 2004 Jul 5;110(1-3):13-27
references: 15177723
references: J Contam Hydrol. 2008 Nov 14;102(1-2):3-16
references: 18774622
references: J Contam Hydrol. 2010 Sep 20;117(1-4):82-93
references: 20685008
references: Environ Sci Technol. 2003 Jun 1;37(11):224A-230A
references: 12831011
references: J Contam Hydrol. 2007 Mar 20;90(3-4):146-58
references: 17157956
references: J Contam Hydrol. 2008 May 26;98(1-2):22-35
references: 18407371
references: J Contam Hydrol. 2002 May;56(1-2):49-74
references: 12076023
references: J Contam Hydrol. 2007 Feb 20;90(1-2):21-40
references: 17049404
references: J Contam Hydrol. 2008 Nov 14;102(1-2):154-71
references: 18757111