By Lynda Myer
In order to minimizing the impact of HS2 tunneling on a sewer has a contract with £4.5m value has been granted to Barhale by Thames Water.
During the operation of HS2’s TBMs underneath, a 75m length of the non-structural liner installation process in north London’s Middle Level Two (ML2) sewer will be done by Barhale.
Including a series of steel hoops installed at 600mm intervals internally to the existing sewer, the intended relining is going to apply additional supports and bracing between them.
While the required access in order to install this liner is due to be provided by two shafts (one existing and a new one), the latter is slated to be built at a point where the HS2 route will be in closest proximity to the sewer to optimize monitoring. Although the form of the shaft’s construction will be as a caisson, to avoid pressure on the Victorian brick sewer, it will be installed using underpinning from the collar rather than by jacking.
Considering that ML2 carries third-party cables, hence extra arrangements have been made to ensure they are not disturbed.
According to Barhale contracts manager Steve Hills: “The work was an important measure. The ML2 has been an important part of the capital’s infrastructure for more than 100 years,” he said. “While it has more than stood the test of time, it is prudent to make sure that it is fully protected as HS2’s TBMs pass below.”
He also added: “Every element of these works has been carefully planned and designed so there is the least impact on the sewer through construction and the maximum protection afforded for the future.”
Additionally, due to the existence of minimal disruption above ground, the objective of minimizing impact had also been applied as Barhale negotiates the area around Regents Park.
