- Client: Developer
- Number of Pumping Stations: 1
- Project Location: Alton, Hampshire
- System Type: Thames Water Sewers for Adoption
Adoptable mains crossing private bridges can be a costly exercise if not executed correctly (especially over the historic and iconic Watercress Steam Railway Line).
Since January 2017, Thames Water and Paradigm have been working closely to complete a design and construction plan for a 1/2 mile rising main that crosses a privately owned listed bridge in Alton with a number of air release valves and washout chambers. The rising main is to serve a new Thames Water Type 3 Sewers for Adoption pumping station for a development of 80 homes.
The bridge, a Victorian construction for the Watercress Line and recently listed, is already showing signs of weakness and disrepair and no recent drawings for existing services were available. In early July, Thames Water carried our trial trenches at either end of the bridge to determine the routes and locations of existing services and the proposed location for the rising main. Carrying out these works gave a clear picture of the space available for the new main.
From these works it was decided that the rising main should be laid under the road in a duct to reduce the risk of having to excavate on the bridge in the future.
Whilst challenging, the design was a success and the new pumping station and rising main are due to go live in January 2018 and be submitted for adoption once the development occupancy level permits.