Environmental Engineering Reference
In-Depth Information
The Stage 2 Botany Groundwater Survey (Woodward-Clyde, 1996) included
an assessment of soil and groundwater remediation technologies available at
the time. A number of technologies were identified that could be applied to
the range of CHCs associated with ICI Australia's historical operations. In
an effort to develop a better understanding of some of the most promising
remediation options, in August 1996, ICI Australia attended a Remediation
Technologies Development Forum (RTDF) conference in the United States
on PRB technologies, which introduced ICI Australia to some of the world's
leading proponents and practitioners of those technologies.
Following the conference, ICI Australia invited a number of Australian
and international experts in site investigation and cleanup technologies—
including both biological and abiotic PRBs—to participate in a project-
specific workshop in Sydney in April 1997. One of the participants of the
workshop was John Vogan, president of ETI. ETI was the commercial arm of
the University of Waterloo established to commercialize the ZVI technology
developed by Professor Bob Gillham and the late Stephanie O'Hannesin at
the University of Waterloo. At that stage, ZVI technology was in its infancy—
the first commercial reactive iron barrier had been installed in Sunnyvale,
California in 1995 (USEPA, 1998). Yet, it appeared that ZVI could be used
in the Southern Plumes where CTC, PCE, and TCE were the dominant con-
taminants, and EDC was a relatively minor component. This was an impor-
tant consideration because it was known that ZVI could not degrade EDC or
dichloromethane (DCM, methylene chloride). At that time, discharge of the
Southern Plumes in shallow groundwater to Springvale Drain represented
the largest mass flux of contaminants from the site to the environment.
However, the Botany site presented some significant hydrogeochemical chal-
lenges that had not been previously encountered with reactive iron barriers:
• Dissolved-phase CHC concentrations up to 220 mg/L
• Low pH (pH < 5)
• Elevated sulfide concentrations (>30 mg/L)
• High dissolved organic carbon (DOC) (>500 mg/L)
• A range of volatile fatty acids
To address these challenges and to enable a thorough evaluation of this
emerging technology, it was agreed that a conservative and rigorous approach
must be adopted. During the workshop, a conceptual design for a pilot-scale
reactive iron barrier was developed. ICI Australia's environmental consul-
tants Woodward-Clyde Pty Ltd, in consultation with ETI, subsequently pre-
pared a proposal for ICI Australia setting out a staged process comprising
• Site selection
• Site, hydraulic, and geochemical characterization (to validate the
selected site and to provide baseline data)
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