2013 PGS Workshop & 11th G.A. Leonards Lecture

4:30 p.m., Friday, April 19, 2013, Krannert Auditorium, Purdue University, West Lafayette, IN

Organoclays: Novel Barrier Media for Managing Groundwater Flow and Transport at NAPL-Sites

Dr. Craig H. Benson
Wisconsin Distinguished Professor, Geological Engineering, University of Wisconsin-Madison

Abstract of Presentation:

Controlling flow and transport of NAPL and aqueous-phase contaminants simultaneously can be challenging, particularly at locations where hydrological isolation is not practical or will adversely affect the surrounding hydrological environment. One strategy is the variably permeable reactive barrier (VPRB), which blocks the flow of NAPL, allows the flow of water, and sorbs dissolved organic constituents in water passing through the barrier.

This presentation describes a case history where organoclay was evaluated as a VPRB medium to manage creosote NAPL and dissolved polycyclic aromatic hydrocarbons (PAHs) in groundwater at a former railroad tie-treating facility. Both NAPL and dissolved-phase PAHs from the facility were seeping into a bay on Lake Michigan, severely affecting water quality and public use of the lake. The VPRB was required to block flow of both NAPL and dissolved-phase PAHs into the lake without appreciable impact on local groundwater flow patterns. Three commercially available organoclays were evaluated. Each was found to be nearly impermeable to NAPL (NAPL conductivities less than 10-8 cm/s) and very permeable to groundwater (hydraulic conductivities on the order of 0.1-1 cm/s), permitting a barrier that blocks NAPL flow while permitting free flow of ground water and removing dissolved PAHs. Water migration in NAPL-solvated organoclay was minimal, but PAHs were released into water contacting NAPL-solvated organoclay. Column tests using dissolved PAHs showed that breakthrough of PAHs did not occur for at least 240 pore volumes of flow (PVF) for two of the organoclays and that all three organoclays maintained high hydraulic conductivity even though they were sorbing PAHs. Numerical simulations showed that an organoclay barrier at the tie-treating site should have a service life of approximately 10 yr.

Craig H. Benson is a Wisconsin Distinguished Professor at the University of Wisconsin-Madison, where he serves as Director of Sustainability Research and Education for campus and is Chair of the Departments of Civil and Environmental Engineering and Geological Engineering. Dr. Benson has a BS from Lehigh University and MSE and PhD degrees from the University of Texas at Austin.

Dr. Benson has been conducting experimental and analytical research in geoenvironmental engineering for nearly three decades, with the primary focus in sustainable infrastructure, beneficial use of industrial byproducts, and environmental containment. His research includes laboratory studies, large-scale field experiments, and computer modeling.

Dr. Benson has received several awards for his work, including the Ralph Peck Award, the Huber Research Prize, the Alfred Noble Prize, and the Croes (twice), Middlebrooks, Collingwood, and Casagrande Awards from the American Society of Civil Engineers and the Award of Merit and Outstanding Practical Paper Award from ASTM. Dr. Benson is former Editor-in-Chief of the ASCE/Geo Institute Journal of Geotechnical and Geoenvironmental Engineering and currently serves as President Elect of the Geo-Institute and Vice Chair of the Executive Committee of ASTM Committee D18 on Soil and Rock. Dr. Benson is a member of the National Academy of Engineering and the University of Texas Academy of Distinguished Alumni.

Geotechnical Workshop: Soilmakers - Engineering Soil for Geoenvironmental Applications
(8:00a.m.-4:00p.m. (includes lunch) East Faculty Lounge, Purdue Memorial Union, Purdue University, West Lafayette, IN)

2013 Workshop Program

Reception and Banquet: 7:00p.m., Friday, April 19, 2013, Purdue Memorial Union West Faculty Lounge, Purdue University, West Lafayette, IN.

Support for the PGS workshop and Leonards lecture is provided by the following sponsors: Earth Exploration, ECS Ltd, Fugro Consultants, Golder Associates, Hayward Baker, Nicholson Construction, Patriot Engineering & Environmental.