March 18, 2021
A new multi-million pound project is underway to make sand and gravel extraction at Wight Building Materials among the most efficient and environmentally-friendly in the UK.
The company has begun the installation of technology called a filter press which dramatically reduces the amount of water used in the processing of aggregate materials.
The press – the only such machine on the Island and one of only a few in the UK used in aggregate production – also means that material produced by way of a by-product of sand and gravel extraction is of higher quality and more quickly available for quarry restoration.
In addition, far less land and fewer lorry movements are required in the treatment process.
It all means water used in the process of sand and gravel extraction will be reduced by 70 percent and what water is required will be recycled for other uses in the business.
Installation of the press is underway and it is expected to become operational in July – ending the traditional practice of using large lagoons to naturally filter water away from extracted materials before this by-product is dry enough to be used in landscaping. These lagoons, which have been used for over 50 years, can now be decommissioned and restored to nature.
The investment in the new technology complements Wight Building Materials’ commitment to managing its land in a sustainable way and will assist its ongoing work with the Hampshire and IW Wildlife Trust to restore quarried sites at St George’s and Prospect Quarry near Shalcombe into prime natural habitat.
Steve Burton, Wight Building Materials general manager, said: “Currently, the existing sand and gravel processing produces a wet silt slurry waste-product that is around 75 percent water.
“This has to be stored in large settlement lagoons. It has to settle over time until it is dry enough to be used for restoration at which point it is removed and taken to the required location by lorry.
“The filter press will treat the processed silt prior to discharge to lagoons by mechanically squeezing out most of the moisture to produce a semi dry material that can immediately be used for constructing landscapes in restoration.”
The British-made filter press comprises 220 polypropylene plates which are shrouded in a filter cloth. Plates are pressed together using a hydraulic ram and silt is pumped under high pressure into the chambers between each plate. Water is ‘squeezed’ out of the silt passing through the filter cloth and sent for recycling.
The process is repeated up to eight times per day creating a steady supply of suitable material that can quickly be used for WBM’s ongoing restoration work.
Steve added: “It is a major investment and also a major logistical project for us to undertake.
“But we are a company that is committed to doing the right thing. We pride ourselves in operating to the highest standards in all we do and, as custodian of such important sites, we want to ensure that we look after the environment around us in the most responsible way.
“We are also proud of our Island roots and another welcome aspect of this project is that we are using, wherever we can, Island businesses to help install the filter press which means partnering up many local companies working in civil engineering, electrics, pipeworks, craneage, transport and constructions.”
Pictures shows (l-r) Steve Burton and project manager Ian Butterworth of Quarry Project Management during construction of the filter press at WBM’s St George’s Down HQ.