We are working closely with the Environment Agency and other key stakeholders to help ensure the effective protection and management of water resources during the design, consenting and construction of Crossrail.
During construction we concentrate on protecting water from pollution and work closely with the Environment Agency to obtain the appropriate consents. A number of our worksites are near water courses such as the River Thames, the River Lea, North Dock in Canary Wharf and the Royal Docks near Excel.
We also monitor our water usage during construction. At many of our sites, it is difficult to harvest and store rainwater but, where possible, we and our contractors do so.
Over 200,000 cubic metres of water was used for construction during 2015-16. This is a reduction of 75,000 cubic metres compared to the year prior which is commensurate with the cessation of tunnelling and other heavy civil engineering. The most water intensive works involved tunnel boring machines and sprayed concrete lining.
Crossrail’s railway systems contractor, Alstom, TSO and Costain (ATC), responsible for the fitting out the railway, requires a variety of plant, materials and fuels to deliver this complex component of works. Amongst these, a 465 metre-long train, operating as a mobile concrete batching plant, pours the wet concrete required to build the new tracks. The train needs to be cleaned daily and a bespoke concrete washout pit is required to facilitate the safe and environmentally acceptable removal of wash water and residual sediment (containing cement, sand, aggregates and petroleum products) whilst reducing waste transfer costs. This wash water is treated to a standard that allows it to be used in fresh concrete batching, saving a significant volume of potable water.
Crossrail is undertaking groundwater remediation at Pudding Mill Lane, Stratford, using ozone sparging and vapour extraction. Due to the various historic industrial uses at the site a source of contamination is in the groundwater. Crossrail together with its contractors and the Environment Agency are remediating over the next year to ensure the area is left suitable for future intended use.
Water saving features have also been factored into the future operational railway. These include low volume flush and leak detection systems for stations and portal washroom facilities as well as rainwater harvesting at the Old Oak Common depot which will be used to wash the new trains.