The Thames Water Ring Main (TWRM) in London is an 80km long, 2.5m diameter tunnel built between 1988 and 1994 to take water from five treatment works and transfer flows via pumping stations housed in shafts along the route. It is a major part of London’s water supply infrastructure and carries an average daily flow of 0.3 x109 gigalitres – a little under one-sixth of the capital’s daily demand.
Barhale was appointed by Thames Water to carry out refurbishment works at Barrow Hill Shaft, one of a total of 22 on the ring main. Located at St. Edmunds Terrace on the edge of Primrose Hill in North London, Barrow Hill is the deepest of the shafts at 80m deep and also the biggest with a four way tunnel connection at its base.
Barhale were employed to upgrade the existing 225mm storm water
pipeline to a 375mm concrete pipeline in order to relieve the flooding
to property number 14, Brindwood Road and increase storage
capacity of the storm water network.
The scope of work consisted of installing 360m of new pipeline along with 8 new manholes, 2 new inspection chambers and the abandonment of the old sewer. The project was always going to be challenging due to its location on a busy residential street.
Careful planning and constant liaisons with the local council allowed it to be successfully completed. Through continuous communication with the residents of Brindwood Road, the project was made easier and in turn positive relationships were formed.
Barhale were contracted By Thames Water and Crossrail to re-lay
several 200 year old Victorian Cast Iron trunk water mains in Sussex
Gardens, which is situated in close proximity to the Paddington tube
and main line stations.
Works were required to provide mitigation to any settlement, which
may have been caused as a result of the Crossrail Tunnel Boring
Machine (TBM), which passed through the area a year earlier. Barhale
were awarded this work due to their experience of working on large
diameter water mains in heavily congested trenches within central
Barhale were contracted to excavate 30 trial holes across Euston area
and within the grounds of Regents Park. Additionally there were 9
window samples and 3 boreholes in the area.
Barhale successfully completed excavating trial holes in highly
sensitive locations whilst considering the impacts on local traffic,
residents and the environment. We utilised acoustic barriers across the works area to reduce our general impact and reprogrammed the works to target the most intrusive trial holes concerning traffic, to be done during the school holidays and weekends.
We also worked tirelessly as we moved through the locations to ensure the communications were carried out ahead of our works.
Rostholme Square is a small estate in Doncaster, South Yorkshire, with a history of internal and external sewer flooding. On behalf of Yorkshire Water, Barhale investigated the cause and developed a solution to resolve the problem. Intensive survey works were carried out, including flooding questionnaires sent to all the residents, giving a holistic view of the problem. The study found that the existing sewer, located in residential gardens of Holly Drive and Rostholme Square, lacked the gradient to achieve self-cleansing velocities so would therefore get blocked, causing the flooding problems. The team also found that the sewer which connected to the downstream network was unable to cope with the flows, causing some localised area flooding in the highway. The results of Barhale’s investigation works altered Yorkshire Water’s proposed solution of a pumping station to a gravity system, resulting in reduced cost and potential disruption. Our proposed solution was to relay the sewer to achieve the required gradient and divert the network connection point from its existing setting to another suitable point. This meant that the team also had to go through some allotment land.
Customers in the village of Haddenham, Cambridgeshire were not
receiving water pressure that met the criteria of new Ofwat (Water
Services Regulation Authority) regulations. As part of the IOS alliance
with Anglian Water, Barhale were contracted to install a new booster
station adjacent to the existing water tower in order to increase the
The extent of the work included installing:
• 30m of new pipework at about 225mm diameter
• A two-pump water booster kiosk
Despite the close proximity of the site to residential properties, the team took care to ensure consideration of the nearby occupants, and the fact that no complaints were received is evidence of this.
As part of Yorkshire Water’s AMP 6 programme, our team in Yorkshire
undertook a scheme to replace 930m of an existing rising main along
Wigton Lane in Leeds.
The scheme was required to replace a section of the existing cast iron
rising main which pumped waste water from Alwoodley pumping
station to the local waste water treatment works along Wigton
Lane. The existing cast iron rising main had deteriorated over the
last few years resulting in several bursts. Consequently, numerous
emergency repairs were required, causing widespread disruption to
the local residents, including road closures and diversions to the busy
surrounding road network. The installation of the new main was to
prevent bursting and resultant disruption to the area.
Remedial measures were required in Mexborough, Yorkshire, where
a number of properties were experiencing 1 in 10 year flood events
due to hydraulically overloaded sewers. Flooding had not only
caused damage to properties, but also nearby infrastructure such as
manholes. The sewers in Market Street are a combined system receiving foul and surface water flows from an extensive upstream catchment. Historic construction works in the area associated with the canal had affected the sewers and led to issues with the network performance during periods of adverse weather. During significant storm events overloading of the sewer network could lead to overland flows affecting local properties, due to the topography. The outline solution was to construct a 700m3 storage tank to capture the excess flows and pump the flows back into the sewer network when the storm event subsided.
Throughout the latter part of 2016, Thames Water experienced a number of high profile incidents on several key Trunk Mains across London. Bursts occurred on mains in the Leigham Vale, Upper Street, Camberwell New Road, Stoke Newington, Lee High Road and Crayford Areas. Once the initial emergency works had been undertaken to restore service, Thames Water developed a planned programme of rehabilitation work, designed to prevent such incidents from happening again in the future.
As part of this project, Thames Water’s eight2O alliance engaged Barhale to rehabilitate the existing 18 inch diameter Palace Road trunk main. This main presented significantly raised risks as it had experienced 5 bursts/leaks in the months prior to the works, and it was anticipated that another major burst would result in the repeat flooding of a number of properties. Overall, the team successfully replaced over 1.2km of main along Palace Road.
Woodman Drive is a small cul-de-sac situated in Rotherham, South Yorkshire. A history of localised internal and external flooding from the sewer during storm events led Yorkshire Water to promote an investigation scheme to try and resolve the flooding. The subsequent investigation carried out by Barhale and GHD found that during storm conditions the main sewer backed up and became overloaded, resulting in the flows backing up the connections to properties flooding them with sewage and escaping out of the gullies flooding driveways. The proposed solution was to lay 47m of new 225mm diameter sewer parallel to the existing sewer in the adjacent A633 Warren Vale Road and abandon the connecting sewer from Woodman Drive to alleviate the flooding. The project was then promoted to delivery stage to install the above solution