Effective Tunnel Ventilation Supplied at the King George V Reservoir

Project Overview

The Thames Water AMP6 Framework was a design and construct programme that had been in place since 2015 and was made up of world class contractors, including the Skanska, MWH and Balfour Beatty (SMB) Joint Venture. The programme comprised of multidisciplinary activities, including the maintenance of water & wastewater treatment works, pipelines, pumping stations, and reservoirs. Under this programme, maintenance at the King George V reservoir was necessary, and ventilation was required whilst site operatives cleaned out two of the reservoir’s underground tunnels. Barhale (working for the SMB joint venture) approached RVT for a solution.

Challenge

Dangerous levels of Ammonia were present within the tunnels that required cleaning. Exposure to this dangerous gas can cause severe burns if it comes into contact with your eyes and skin, even causing burns to your respiratory tract and lungs if inhaled. Therefore, it was vital that the gas was effectively controlled and a level of clean airflow through the tunnels was provided whilst the cleaning took place.

Solution

To achieve effective ventilation of the tunnels, a 450S Ventex® centrifugal fan was placed at the shafts of both the King George V Reservoir and Maidensbrook. Flexible duct runs were then fed through the manholes of the shafts, allowing these fans to vent in fresh air at each end of the tunnels. The contaminated air then exited through the manhole at the top of the Albany central shaft. As all the shafts are covered (to stop people falling in) and these small manholes are the only entrance and exit points, an additional 450S was sited at Albany to aid extraction through this restricted space.