HS2 Bromford Tunnel

HS2 is one of the largest and most complex civil engineering projects to be undertaken in the UK for many years, and it is these large scale complex infrastructure projects which WJ specialise in.

WJ were engaged by BBV JV to install a depressurisation groundwater control system and undertake groundwater monitoring as part of the construction works for the Bromford Tunnel Intermediate Ventilation Shaft to the east of Birmingham.

The ventilation shaft, located centrally between the two tunnel bores, with cross-connections into the tunnels at track level was 43m in depth and almost 19m in diameter, constructed via diaphragm walling, with a secondary inner lining for the lower part of the shaft, and sprayed concrete lining (SCL) connections to the running tunnels either side.

An array of passive relief / dual purpose wells were installed within the shaft footprint itself to provide a flow path to relieve the groundwater pressures within the Mudstone and prevent the risk of basal heave during the excavation and construction works. The dual purpose wells provided capacity should a passive system not be sufficient and it was necessary to undertake groundwater pumping.

In addition to the dewatering wells, a series of fully grouted multilevel vibrating wire piezometers were installed within boreholes within the shaft to provide ‘real time’ groundwater monitoring data to both WJ staff and the client via our bespoke online cloud monitoring portal.

• LOCATION: Birmingham

• CLIENT: BBV JV / HS2