February 2005 Meeting Abstract
Successful Remediation Project at Typical Brownfield Site with Tight Soil Matrix
An innovative three step remediation approach was applied to successfully treat groundwater at a site with a very tight soil matrix. The first two steps involve chemical oxidation. The third step is a bioremediation polishing step applied to the remaining desorbed contaminant mass. This break through approach avoids Traditional Fenton’s free radical chemical oxidation fate and transport limitations. Fenton’s free radicals are typically not applied in very tight soils since they are limited to a fate (shelf life) of seconds and minutes.
A case history will be presented describing the successful field application of sodium persulfate solution (first remediation step), which was subsequently activated by an in-situ application of a Traditional Fenton’s Free Radical Process (second remediation step). This break through approach allowed the sodium persulfate sufficient time, which has a fate (shelf life) of about a month, to transport to the source of the groundwater contamination within the tight soil matrix.
Bench scale studies had previously indicated that sodium persulfate could be activated with a transition metal catalyst (ferrous iron) and by raising the groundwater temperature to 140-1700F. At the typical Brownfield Site, the sodium persulfate was activated by ferrous iron, which is also the catalyst for generation of the Traditional Fenton’s Reagent. The sodium persulfate was simultaneously activated to form sulfate free radicals by raising the groundwater temperature through the exothermic process of generating Fenton’s Free Radicals.
Bench scale studies had indicated that use of high temperature (greater than 180oF) chemical oxidant applications in the saturated zone negatively impacts the subsequent bioremediation polishing step (third remediation stage). Use of low temperature (less than 100oF) chemical oxidant applications in the saturated zone resulted in dissolved phase rebound problems. When the saturated zone temperature is maintained consistently between 140oF and 170oF, contaminants are still effectively desorbed from the tight soil matrix through a mass transfer partitioning process without overly stressing the indigenous biological species needed for subsequent bioremediation while avoiding subsequent dissolved phase rebound problems.
Biographical Sketch
Richard T. Cartwright P.E., CHMM, Senior Vice President, MECX, LLC
8096 Clarherst Drive
East Amherst, NY 14051
Phone: (713) 412-9697
Fax: (713) 585-7049
E-mail: richard.cartwright@mecx.net
Mr. Cartwright has an MBA in Operations Management from Indiana University, BES in Chemical Engineering from Brigham Young University, and Professional Certificate in Project Management from University of Buffalo. Has over 30 years of experience at hazardous & solid waste landfills, brownfields, manufacturing facilities, chemical plants, oil refineries, terminals, pipelines and retail petroleum outlets. He is a Past President of National Academy of Certified Hazardous Materials Managers.
Please plan on joining the BAPG for this interesting discussion.
Michael C. Alfieri
BAPG Executive Vice-President