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ISCO Remediation of Dry Cleaner

Premier completed the Remediation Work on budget and on time, which allowed the Client to meet their Planning Objectives.


Premier Environmental Services Inc. was retained by the owner of a multi-tenant commercial plaza in Toronto, Ontario, to assess and remediate environmental impacts caused by dry cleaning. Detailed investigations confirmed that past solvent management practices resulted in soil and groundwater contamination with PCE and its degradation products. Cleanup was required in order to address potential health concerns and to prepare the property for re-financing and/or divestment.


The solution identified by Premier included both the physical removal of soil contamination beneath the former dry cleaning equipment and in-situ chemical oxidation (ISCO) of the groundwater plume. Targeting the source area was important, but soil removal was difficult due to space constraints, underground utilities, geotechnical considerations, and the importance of keeping their tenants operational. It was also necessary to design an oxidant delivery system capable of overcoming injection into dense glacial soils.


Over thirty monitoring wells were required to delineate the groundwater plume. The source zone excavation was completed in April 2012. Prior to backfilling and restoration, the excavation was ‘seeded’ with potassium permanganate oxidant and a horizontal injection gallery was installed. Pilot-scale testing confirmed the pre-design parameters for ISCO after which a series of sodium permanganate injections were completed using both the horizontal gallery and ten vertical injection wells. Monitoring of subsurface conditions during injection events and confirmatory groundwater sampling after every event were conducted to evaluate remedial effectiveness and make necessary system adjustments. By early 2015, Premier was successful in remediating almost 90% of the contamination. This has resulted in the site now meeting the applicable Ministry of the Environment and Climate Change (MOECC) Table 3 commercial standards.

The first of four post-remediation quarterly sampling events has confirmed the groundwater continues to meet the standards. Once the additional sampling is completed, Premier will submit a Record of Site Condition (RSC) for acknowledgement by MOECC.

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