Objective:

The objective of this project is to demonstrate the in situ microcosm array (ISMA) technology for remedial design of chloroethene remediation and to develop a guidance document and workshop, both based on real-world experience gained and data collected. The ISMA technology answers key questions frequently posed by remediation regulators and decision makers: (1) Are contaminants being attenuated naturally, and if so, at what rate? (2) Can this rate of contaminant removal be accelerated? (3) Among the available active remediation approaches, which one will perform most favorably at the site and what is the ideal dosage regime for any given chemical or biological supplement? (4) Is active remediation economically attractive when compared to natural attenuation? And, finally (5) will the manipulation of environmental conditions at the site lead to unwanted effects, such as sediment clogging or solubilization of toxic metals?

Technology Description:

The ISMA apparatus is a self-contained, field deployable device suitable for conducting up to 96 column experiments simultaneously in the subsurface (i.e., in situ). Groundwater is drawn by a submersible multichannel pump from the screened interval of a deployment well and fed to in-situ sediment columns at the natural rate of groundwater flow. Replicate sediment columns are configured to assess natural attenuation plus various distinct treatment approaches (e.g., biostimulation, bioaugmentation, chemical oxidation). For a fair comparison of mutually exclusive treatment approaches, in-situ column studies on transformation of various chlorinated ethenes are conducted simultaneously in situ in the same well with the same feed water. Upon incubation in flow-through mode in a well for a sufficient time period (e.g., 4 weeks), the device is retrieved and sent to the laboratory for chemical and biological analysis of the sediment columns and their individual effluents that are captured during field deployment. All tests are fully contained, yet conducted in situ. Upon retrieval of the device, no trace is left behind. Deployment wells can continue to serve as sample locations for compliance monitoring.

Expected Benefits:

This project will produce guidance and convene a workshop on how to use in-situ column studies for obtaining site-specific remedial design information for mutually exclusive treatment approaches to clean up chloroethenes in contaminated aquifers. The ISMA technology is projected to cost less than laboratory studies and eliminates the risk of well contamination with chemicals or clogging of the well and subsurface formation from biomass build-up during in-situ feasibility tests. Key remedial design information can be obtained, such as the rate and extent of chloroethene transformation in situ. ISMA deployment also protects expensive monitoring wells, which may lose their value for compliance monitoring if conventional in-situ treatability tests are conducted that require the injection of test substances whose effects are uncertain. (Anticipated Project Completion - 2011) 

Principal Investigator:

Dr. Rolf Halden
Arizona State University
Center for Environmental Biotechnology
Tempe, AZ 85287-5101
Telephone: (480) 727-0893
Fax: (480) 727-0889
E-mail: rhalden@asu.edu

DoD Liaison:

Dr. Nancy Ruiz
Naval Facilities Engineering Command Engineering Service Center
EV411
1100 23rd Avenue
Port Hueneme, CA 93043
Telephone: (805) 982-1155
Fax: (805) 982-4304
E-mail: nancy.ruiz@navy.mil