Thames Water Greenwich Pumping Station serves a 28mile2 catchment area in South East London. To the rear of the pumping station is the Inlet Penstock Chamber (wet well). Within this chamber there are 5no. penstocks which are used to isolate incoming and/or outgoing flows depending on operational requirements. The existing penstocks were installed in the early 1900’s.
The scope of works required the replacement of five penstocks and actuators along with deck steelwork, flooring mesh and handrails. The project had a direct impact on the new Tideway CSO, as it was in close proximity to this wet well, and the new penstocks would provide safe and secure isolation for Tideway works to proceed.
Upon inspection of the wet well, it was observed that the North wall of the chamber was in poor condition and badly deteriorated from constant exposure to H2S. Whilst studying historic drawings of the chamber, Gel Engineering noted the absence of two structural arches within the chamber and the presence of a significant vertical crack in the brickwork. Core samples of the brickwork were taken and analysed to determine the extent of any deterioration which aided the decision to reinforce the wet well in advance of penstock replacement works. This led to the design and installation of a semi-permanent steel bracing structure which effectively emulates the original arches which had been removed previously.
Gel Engineering used diamond wire cutting to remove the existing penstock frames from the chamber walls. This method ensured that each penstock frame could be suspended from a gantry crane and cut clean from the wall without putting operatives at risk.
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