Case Study: Kingston Power Station Encapsulation
Client: United House Ltd
Budget: In excess of £3,000,000
To design an offsite engineered solution to construct a secure, insulated precast concrete structure around the existing substation to encapsulate it and enable surrounding land to be safely developed for the Kingston Heights residential and hotel development.
An area of land primed for development in the heart of Kingston, south west of London, needed to be made suitable for residential and commercial use. In order to make this possible, Charcon Construction Solutions were commissioned with the encapsulation of an existing UK Power Networks (UKPN) substation located on the site.
Construction was carried out in conjunction with UKPN who enabled transformer outage during certain phases of the works, providing a safe environment for crews and an uninterrupted power supply to customers in Kingston and the surrounding area.
The resulting four storey enclosure consisted of steel lined, precast concrete columns, infill panels and bridge beams weighing upwards of 65 tonnes, with an average length of 35 metres and a depth of 1.7 metres.
Project Considerations and Solutions Used:
The original design was for a steel structure but later converted into precast, with steel RSJ’s embedded into precast, prestressed concrete bridge beams in spans of 35 metres. The structure also incorporates precast concrete columns, wall panels and head beams, chimney stacks and also includes two 25m high large box section vent shafts.
For the supply of the major precast components, Charcon partnered with Bannagher Precast Concrete.
The logistics for the safe transportation of such large concrete components had to be meticulously coordinated – beams were shipped from Ireland to Liverpool and accompanied across the M25 by police escort after rush hour traffic periods, with up to three onsite deliveries being made per evening.
In order to install the beams, specialist equipment had to be employed, in this case a 1,200 tonne mobile crane used to lift the fifty 70 tonne ‘U' shape beams that form the podium deck. The beams sit on designed elastomeric bearing pads, the deck slab is formed with fibre and GFRP rod reinforced concrete slabs which form a permanent shutter to the insitu slab as per bridge deck design. Other unique design features are Super Y Edge Beams stitched together using insitu concrete diaphragms tpo give clear spans of 35m in one direction and heavy duty prestressed wideslab giving 8m clear span in the other direction.
The project demonstrated how long span concrete bridge beams can meet the design criteria of a complex structure and be delivered and installed within a busy city centre location. The completed project was on time, on budget and to the satisfaction of the client. The encapsulation structure allows prime real estate land in the heart of Kingston to be developed for housing and leisure use.
Kingston Heights is a £70 million mixed use development in the Royal Borough of Kingston upon Thames in south-west London on behalf of NHP Leisure Developments.
It will comprise 136 residential units, including 80 private apartments and 56 affordable homes which will be managed by national affordable housing provider Affinity Sutton. A150 bedroom hotel with meeting, banqueting and conference facilities is also planned.