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    ISCO Treatment Achieves Closure on Arizona Superfund Site

    Benzene Contamination Treated to Non-Detect with Single PersulfOx® Application

    Project Highlights

    • Previous remediation attempts included soil vapor extraction coupled with groundwater pump and treat/air sparging.
    • PersulfOx was applied via gravity-feed through existing remediation wells.
    • Single application of PersulfOx resulted in benzene reductions of 1,000 ug/L to non-detect.
    • Site closure achieved
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    Project Summary

    Persistent benzene contamination at an Arizona Superfund Site kept the state regulatory agency from closing the site. The City of Tucson maintenance yard contained low residual concentrations of benzene around 1,000 ug/L in a single well. An initial remediation approach used soil vapor extraction coupled with groundwater P&T and air sparging, however results did not meet site closure criteria.

    When considering alternatives, the State of Arizona wanted to be efficient by using the existing remediation wells. As a result, Regenesis worked with the state to design a PersulfOx application using the existing infrastructure. Regenesis worked with the state to design and assist with the application of PersulfOx® using the existing remediation wells. After one application, benzene contamination levels were non-detect in the offending well and site closure was achieved.

    Remediation Approach

    The treatment approach was a trial by the State of Arizona to apply PersulfOx via gravity-feed directly into the existing remediation wells to target residual benzene concentrations. By using the existing in situ infrastructure, the cost of the one-time PersulfOx application was less than $15/cubic yard.

    Technology Description

    PersulfOx is a sodium persulfate-based chemical oxidation technology which destroys both hydrocarbon and chlorinated solvent-type contaminants in the subsurface. PersulfOx contains a built-in catalyst which activates the persulfate component and generates contaminant-destroying free radicals without the need for the addition of a separate activator.