Project

Treatment of Chlorobenzene and BTEX impacted soil and groundwater. Treatment area 730 m² to depth of 9 mbgl.

Remediation techniques used include Steam Enhanced Remediation (SER), Groundwater pumping, Vertical and Horizontal Soil Vacuum Extraction (SVE) and Air Sparge (AS).

Challenges

Chlorobenzene has an exposure limit of 1 ppb. A high-rise building situated next to the site was identified as an immediate receptor. An enclosure was erected around the excavation and ventilated through Activated Carbon tanks. Following excavation of contaminated soils, in-situ equipment was installed to treat groundwater to a depth of 9 mbgl. The enclosure was removed.

Churngold Solution

The SER system injected steam via a buried ring main into shallow and deep steam wells. Steam injected was pulsed in different areas of the target treatment area.

Volatile contaminants were removed utilising large diameter horizontal wells (situated above the groundwater capillary zone) and vertical DPVE wells.

Results

A maximum groundwater temperature of 103^oC was achieved during the steam injection. On commencing polishing, subsurface soil temperatures between 50 to 65^oC were recorded. Temperatures reduced only 15^oC over a six-week period providing optimal conditions for biodegradation.

An estimated total VOC mass removal, of 2,675 kg was delivered by the SER treatment. Mass recovery peaked at 475 kg per week during steam injection.

Current Status

SER successfully delivered a 75% reduction in groundwater contaminant mass (VOC and TPH). A further 15% reduction was achieved through a targeted excavation. This identified a number of subsurface structures, which likely limited steam treatment efficiency. Overall the multi-treatment approach provided for the future protection of the adjacent river course (to the Environment Agency satisfaction), whilst the highest standards of health and safety were maintained.