Case Studies

Project Sunflower

Remediation & Enabling

The site comprised a redundant research facility which required safe decommissioning and demolition prior to construction of a new office building.  Investigation works confirmed that a former waste solvent UST had leaked, with an impacted source zone up to 19.0mbgl consisting of a variety of volatile organic compounds including BTEX and Chloroform.

Aside from the complex and variable site geology, and the variety of contaminants requiring treatment, the works had to be undertaken on a restricted timetable to enable ongoing construction works to commence over the source area.
The client's stringent standards of quality, health, safety and environmental management were adhered to at all times on one of the most technically challenging projects ever undertaken in the UK.

Tamdown implemented an integrated solution adopting stringent health and safety procedures and best-practice, working closely with the client's overseeing consultants, AECOM:

• Safe decommissioning and removal of all contaminated ductwork, air handling units etc from the building;
• Controlled demolition of the research building, grubbing out slabs/foundations and crushing for re-use;
• Sheet piling, excavation and removal of the waste solvent UST and surrounding VOC contaminated soils to 6.2mbgl;
• Thermal treatment of the source zone in three separate horizons (2x sand aquifers and sandy clay aquitard) to 19.0mbgl, using a combination of steam-air sparging and thermal conductive heating, with subsequent extraction using ATEX multi-phase and dual-phase systems; and,
• Following successful pilot trials, residual treatment of the down-gradient plume through injection of a slow-release organic substrate to stimulate accelerated biodegradation of residual VOC concentrations.

Overall, Tamdown successfully treated 17,862 tonnes of contaminated soil and groundwater with minimal disruption to the surrounding facilities.

Due to the complexity and innovative nature of Project Sunflower, Tamdown were highly commended runners up at the Brownfield Briefing Remediation Awards 2011 in the Best In-situ Treatment category.