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Gatwick Stream Attenuation Scheme

Client: Gatwick Airport Ltd

Value: £0.4m

Contract: NEC3

Enabling works package for Gatwick Stream Flood Attenuation project.


Dyer & Butler delivered an enabling works package for the Gatwick Stream Flood Attenuation project, which consisted of supervising over 30 archaeologists for over six weeks while they cleared the area for the subsequent project. Further works were instructed during the course of the project which included 240m of ducting for a UKPN HV cable diversion and construction of a haul road and compound, which required importing 5,000 tonnes of materials. Permanent works were also carried out which included a passing lay-by and improved bellmouth improvement on to the West Sussex County Council owned road, earthing rod installations works and finally a topographical survey of the existing lagoon.


The most challenging element of the project was to construct an economical haul road for the main contractor within a short 10-day window once the archaeological team had completed the required investigation. The haul road required topsoil strip and importing of 5000 tonnes of material to withstand over 200 movements a day of 20T haulage lorries. There is a total of 20,000 lorry movements expected lorries during the course of the New Lagoon works (by others). As an alternative to a full thickness DOT type 1 material for the haul road, we suggested making the base with recycled roofing tiles which were given 6F5 classification. This was then capped with Type 1 to help binding of the material below. This saved the client considerable cost on the temporary haul road.


During the course of the project we managed to recycle 95% of materials used or removed as part of the works. During the haul road construction we reused the muck removed and built bunds alongside it to provide stability and also to minimise visibility of the works to incoming pedestrians and vehicles. We used 100% recycled roofing tiles to form the base of the haul road which reduced the amount of DfT Type 1 required which in turn is a more economical and environmentally friendly product. Finally works were alongside the Gatwick Stream which from start to finish had no incidents, spillages or affected the wildlife present. Temporary set up for the work activities were communicated to airfield operations at the earliest opportunity and the necessary approval sought


The biggest challenge we faced was getting the approval and required paperwork in place from West Sussex County Council (WSCC) for the S278 agreement. Due to the application process of the 278, this cannot be applied for until GAL had obtained planning approval for the main project. There was a risk that the main works could be delayed until the Bellmouth improvement was completed to WSCC satisfaction, however by using a designer that was familiar with WSCC requirements and working in close contact with WSCC, we successfully improved on the standard leading times with the local authorities. Another key challenge was to catch up the lost time caused by the archaeological find to complete the haul road on time which we successfully delivered.



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"As someone who has spent his working life in the construction industry, I was very impressed with the professionalism and standard of workmanship carried out by your employees."

Cllr. Mike Curtis,
Romsey Town Mayor