Environmental Engineering Reference
In-Depth Information
had issued a report on site investigation, the ICI Botany Groundwater Stage 2
Survey (Woodward-Clyde, 1996), which was a thorough investigation of con-
temporaneous and historical operations, hydrogeology, impacted soil, ground-
water, surface water, sediment, marine biota, soil vapor emissions, and related
human health risks in and around ICI Australia's Botany site. The Stage 2
Survey also included a section on remediation technology options, including
zero-valent iron (ZVI) permeable reactive barriers (PRBs). ZVI PRB technology
was identified as the preferred technology for remediating shallow groundwa-
ter discharging into a surface drain known as Springvale Drain. To evaluate
this and a number of other cleanup options, ICI Australia (and subsequently
Orica) embarked on a program of remediation technology review, research,
and development, which continues today.
As one of the first steps in this remediation technology research program,
ICI Australia convened a workshop in April 1997, inviting a number of lead-
ing Australian and international experts on contaminated sites. One of the
workshop participants was John Vogan, president of ETI, who discussed
potential application of the reactive iron barrier. ETI presented ICI Australia
a proposal for a staged process to evaluate reactive iron barrier technology
in the context of the Botany groundwater.
The purpose of the barrier was to evaluate the efficacy of the technol-
ogy for destroying a number of specific aqueous-phase CHCs. Therefore, a
pilot-scale barrier was designed conservatively—based on results of exten-
sive laboratory column trials—and was constructed as precisely as possible,
incorporating a large array of monitoring locations. An initial monitoring
period of 9 months was extended to 19 months, although subsequent infre-
quent monitoring has revealed some significant developments in the bar-
rier's cleanup capabilities.
Being the first of many kinds, this technology evaluation project presented
a number of significant design, procurement, and construction challenges.
12.2 Background
Orica (and its predecessor ICI Australia) has manufactured a wide range of
organic and inorganic chemicals at its Botany site—now known as the Botany
Industrial Park (BIP)—since the early 1940s. The first stage of a ChlorAlkali
Plant was commissioned in 1944, producing chlorine, caustic soda (sodium
hydroxide), and hydrogen. To facilitate expansion of caustic soda production,
downstream CHC plants were progressively added, including
• Carbon tetrachloride (CTC), 1945-1952
• Trichloroethylene (TCE), 1948-1977
• CTC and tetrachloroethene (perchloroethylene, PCE), 1963-1991
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