Challenging remediation project

A sophisticated soil remediation technique recommended and implemented by May Gurney enabled an important project to improve facilities at Newlyn Harbour to be carried out within the available budget.

Newlyn Pier and Harbour Commissioners had potential funding to add a new pontoon berthing facility at the harbour - but in order to build the new facility, part of the harbour bed had to be dredged to create sufficient depth of water.

However, the silts on the harbour bed were contaminated with organic tin and other heavy metal contaminants - probably as a result of the repeated scraping and re-painting of boat hulls with anti-fouling paints, at low tide.

Under the new Landfill Directive the disposal cost of contaminated soil has increased significantly. Coupled with this, there is only a handful of landfill sites in the UK that can accept contaminated soils - and none of these are anywhere near Cornwall.

The traditional 'dig and dump' approach was prohibitively expensive - it would have added around £2m to the project cost, which would have prevented it from going ahead.

As an alternative, May Gurney suggested Stabilisation/Solidification (S/S) - a remediation process that reduces the hazard potential of waste by converting the contaminants into their least soluble, mobile or toxic form. May Gurney has been at the forefront of developing this technique in the UK since the mid 1990s.

A treatability study indicated that S/S would substantially reduce the leachability potential for the contaminants. And costs fell from £2m to approximately £200,000 for dealing with the contaminated silts - bringing the total project cost below the Harbour Commissioners' capped budget, which enabled funding to be approved.

In addition to the remediation work, May Gurney was also able to undertake the wider civils works required to design and construct the new berthing facility.

The work started in mid February 2006 and approximately 7,300 cubic meters of contaminated silts were stabilised before the end of March. The silts were excavated from the harbour during low tide and stockpiled to await processing.

This element of the work is now complete and the civil engineering will be finished during summer 2006.

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