Siltbuster Joins the UK’s Largest Concrete Repair Project
The largest concrete repair project ever in the UK is underway on the M5, with Siltbuster assisting the Bam, Morgan Sindall, Volkerfitzpatrick joint venture to comply with their environmental obligations, preventing highly alkaline hydrodemolition blast waters from entering the canal network which runs underneath the motorway deck.
As one of the busiest routes in the country, the M5 Oldbury Viaduct carries 120,000 vehicles each day over around 3 km of elevated motorway. This section passes over industrial estates and residential areas of Oldbury in the West Midlands and connects the North with the Southwest. The essential works will cost in excess of £100 million, repairing concrete along the expansion joints and waterproofing the motorway deck.
Bam, Morgan Sindall, Volkerfitzpatrick (BMV JV) is the principal contractor, with Volkerlaser and Concrete Repairs heading up the project. On site there are three hydrodemolition contractors – Sabre Jetting, Buxton Water, and Rentajet – who are using the technique to remove the old concrete and expose and retain the expensive existing reinforcement bars. This process creates concrete blast water, which if released without treatment would pollute the Birmingham Canal Navigations, which run underneath the M5. Such blast water typically has a pH of 12-13, which is the same as domestic bleach, so its potential impact on vegetation, ecosystems and aquatic life, if untreated, is huge. With the works estimated to take around 18 months, offsite removal of the blast waters via tanker would be cost prohibitive, hence BMV JV called in Siltbuster.
From its extensive hire fleet, Siltbuster is currently supplying 4 HD units and 2 DS4 FB50 systems which are designed to neutralise the high pH waters and remove suspended solids. Both innovations utilise carbon dioxide to neutralise the alkaline waters instead of mineral acids such as Hydrochloric, Sulphuric or Nitric acid. The use of carbon dioxide not only brings numerous environmental advantages, but it also removes the practical safety issues surrounding the storage and handling acids. In addition the use of carbon dioxide allows for significant cost savings to be made over the duration of the works, with neutralisation of blast waters via mineral acids costing in the region of £2.55 per m3 whilst neutralisation of blast waters via carbon dioxide costing in the region of £0.33 per m3.
The compact and easily transportable HD units have been deployed at locations along the works where access is restricted. The Siltbuster HD unit operates continuously with flow rates of 1-5m3/hr and can be powered from an external 110V power source or using its own internal battery, making it ideal for remote locations.
In areas where space is less restricting, Siltbuster DS4 FB50 systems are being utilised. These units are capable of treating much higher flow rates than the HD units, reaching up to 20m3/hr. In certain areas of the works, these units are not only being used to treat the hydrodemolition blast waters but, also the surface water runoff after heavy rainfall from the motorway deck which has also taken on an alkaline nature due to the repairs.
Dr Richard Coulton, CEO at Siltbuster, comments: “It’s great to once again see Siltbuster equipment and expertise being utilised on such a prestigious construction project. No two projects are the same, which is why our ability to create bespoke solutions in even the most challenging environments is so in demand.”