CABBAGES AND HEMP were the subjects of a contaminated land presentation at a recent ICE Gloucestershire and Wiltshire Branch meeting.
Chris Wallace of May Gurney explained that if the Government's target for housebuilding on brownfield sites is to be achieved, clients must start looking beyond the conventional approach of 'dig and dump' when dealing with contaminated land.
Wallace discussed various land treatment methods such as removal or encapsulation, and process based methods, such as soil washing. Innovative techniques described included the use of biological organisms to compost hydrocarbons and growing hemp to remove heavy metals.
According to Wallace, Hungary is leading the field in sustainable monitoring techniques including growing cabbages on brownfield sites to demonstrate the contamination concentrations.
The main focus of the talk was an in situ remediation technique, whereby Modified Organophillic Bentonites, Ordinary Portland Cement and Pozzolans are mixed into the soil in situ by auger. Secant columns of treated soil can be used to contain contamination passively by providing an impermeable barrier.
Wallace believes that under current legislation, in situ remediation remains difficult to justify unless removal presents significant technical challenges and, consequently, higher costs.
He said: 'The requirement to operate in situ systems under the existing waste management regulations is putting further obstacles in the way of what is a stated Government initiative. While innovative systems do exist, their development must be encouraged by a sensible framework of legislation and regulation.'