Chromium contamination, near Falkirk

Challenge

The local authority wished to regenerate this former multi-use industrial site in order to create a landscaped public amenity space. 

However, high levels of hexavalent chromium were present beneath parts of the site and were leaching into groundwater and thence entering the river system at concentrations greatly exceeding Environmental Quality Standards.

The challenge faced by ERS was to design a remotely operated system that would remove chromium from the groundwater over the long term. This solution would need to be safe, reliable and cost-effective and could only occupy a small footprint at the site. 

Solution

Following pilot trials, ERS scientists and engineers developed a pioneering chemical treatment method for chromium removal.  The ex situ system utilised automated dosing and control of pH and redox conditions to facilitate the removal of contaminants.  A secondary, passive remediation system using zero-valent iron was installed to treat groundwater under high flow conditions, where discharge rates risk exceeding ex situ plant specifications.

Outcome

• Design and operation of innovative and highly effective treatment plant.
• The system - with a 25 year lifespan - is capable of treating 200 m3/day, reducing chromium concentrations from  >10 mg/l  to <0.01 mg/l.
• Awarded "Most Innovative Chemical Treatment", Brownfield Briefing Awards 2007.