Neutralisation of malodours from contaminated land

A mobile air misting system was installed for part of the land reclamation area, to remove the smell from excavated material such as strongly odorous containers of phenolic residues and mercaptans

Walters Group are the largest independent civil engineering firm in Wales, undertaking civil engineering, building, mining, quarrying and land remediation projects.

Walters own and operate over 250 items of plant.

Walters UK are currently involved in a land remediation project at Castle Gate, Caerphilly.

The site has been acquired for redevelopment to provide housing and leisure facilities.

The 60-acre site was historically used as a landfill in the late 60's and early 70's.

The project started in January 2004, with the industrial waste excavation starting in April 2004.

The excavated material included strongly odorous containers of phenolic residues and mercaptans, in addition to more general waste odours.

Walters UK were conscious of the odours affecting their operating team and the local residents.

Likewise, the Environment Agency and local Council wanted to know that the odour issues were being addressed.

In April 2004, following consultation with Eco Technology, a mobile air misting system was installed for part of the working area, with a perimeter of 250 metres.

The system operates at a pressure of 6 bars, and can be configured to spray between 1 and 2 litres per metre per hour.

Walters UK were supplied with the liquid Super F product 888NF.

Super F 888NF is particularly suited for general waste applications including waste removal vehicles and waste transfer stations.

The product may be diluted up to 1:500,000 and still remain effective.

According to the dilution used the Super F 888NF can either be used to neutralise the offensive smell or used at higher concentration to leave a residual pleasant "perfume".

For this project the 888NF has typically been sprayed at dilutions of 1:15,000, with the result that odours have been significantly reduced, if not eliminated, and making working conditions on site much more pleasant.

In addition the site has stock of a second Super F product SFA Plus Mercaptans "S" in preparation, should another pocket of mercaptans waste be unearthed.

With the success of the first air misting system, two further systems had been installed by June 2004 to cover a much wider area, with perimeters of 150 and 225 metres respectively.

Furthermore, Walters UK have used Super F 888NF with a bowser to dilute and spray directly on the contaminated ground to neutralise the odours at source.

Walters UK are hoping to complete the waste excavation aspect of the project by mid July 2004, with all further remediation and infrastructure completed by January 2005.

Mr Robert Thompson (Project Manager) has been very impressed by the service and the misting systems, on which he commented "the service has been excellent.

Every time we have asked Eco Technology for assistance they have pulled out all the stops: given the design of the systems we have been able to move and reset them around the site ourselves, all relatively simply".

With regards to the 888NF he has commented that "without the Super F we would have been hard pressed to carry on working on the project on certain days, it has provided great odour neutralisation by application at source and an overall significant reduction in odour over the site".

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