332 ABSTRACTS

the feasibility of the technology and to optimize the operation parameters if the technology is consid- ered the best remediation alternative for the given conditions.

Electro-kinetic cells have been designed, fabri- cated and assembled. Special devices to consoli- date the sample to the required void ratio have been designed and fabricated. Flow volume measure- ment panels have been designed, fabricated and as- sembled. The electrical circuit has been designed and is being connected. Automation of the experi- ment by means of a computerized data acquisition system is underway. The first trial sample is being saturated by sodium chloride solution and consoli- dated to the required void ratio.

The continuation of the project will expand this work by developing a numerical model for the im- proved coupled flow theory, and performing prop- erly designed experiments to evaluate the viability of the technology for extracting different contami- nants under different subsurface environmental con- ditions and the validity of the developed theoretical model.

F I E L D D E M O N S T R A T I O N OF A C O U S T I C A L L Y E N H A N C E D S O I L W A S H I N G S Y S T E M F O R IN-SITU T R E A T M E N T OF L O W P E R M E A B I L I T Y

S O I L S

Theodore Cleveland Department of Civil & Environmental Engineering, University of Houston, 4800 Calhoun, Houston, Texas 77204-4791, U.S.A.

In-situ treatment of contaminated soil is economi- cally and operationally attractive for soils where ex- cavation is infeasible. Destruction of contaminants attached to soil particles is difficult because these contaminants are strongly sorbed to the soil parti- cles and become relatively immobile. A method to mobilize such strongly sorbed contaminants is re- quired for in-situ treatment of low permeability soils.

The objective of the continuation of this research is the development, explanation, and demonstration of an in-situ treatment/recovery enhancement tech- nique that mobilizes contaminants in low perme- ability soils. The technique uses acoustic excitation to stimulate contaminant migration by suspending fines for subsequent recovery under the influence of induced hydraulic gradients. The literature indi- cates that the excitation also generates a localized

electric potential that alters the ability of contami- nants to adsorb onto mineral surfaces. The first mechanism is probably the dominant mechanism for practical application and has been demonstrated in laboratory experiments conducted during the re- search covered by the initiation grant (101UHH0215), the second mechanism is postu- lated to be more subtle but is potentially more use- ful in very tight formations.

The continuation research will cover the field demonstration of the technique in an injection/with- drawal test similar in concept to a standard radial dispersion test using fluorescent dyes as surrogates for organic compounds. The demonstration will show that acoustic excitation can enhance recovery of strongly sorbed contaminants at the field scale, generate data to help explain the mechanisms of en- hancement, and develop design guidelines for prac- tical application of the technique in low permeability soils.

S O N O C H E M I C A L T R E A T M E N T OF H A Z A R D O U S C H L O R I N A T E D H Y D R O C A R B O N S IN W A T E R AND S E D I M E N T S

James W. Catallo, Thomas Junk and Robert P. Gambrell Wetland Biogeochemistry Institute, Louisiana State University, Baton Rouge, Louisiana 70803, U.S.A.

The presence of hazardous waste (HW) mixtures in sediments and aquifers of the US constitutes a ma- jor challenge in terms of developing effective and economically feasible remediation technologies. In cases where significant environmental volumes are contaminated with refractory chemicals, it is desir- able to deploy treatment systems that deliver energy to the sediment-water system in amounts great enough to: 1. strip chemicals from sediment surfaces

2. chemically modify or degrade many of the compounds in the mixture and/or

3. increase the net mobility of remaining compounds so that secondary treatment procedures will be enhanced There currently is a lack of treatment approaches

that meet these criteria and are feasible for in situ

remediation of contaminated systems. Although not generally appreciated, it is well es-

tablished that physical events associated with ultra- sonication of aqueous solutions and suspensions produce extremely energetic conditions that can af-