GASHCO Interceptor Installation, Gatwick

Client: GASHCO

Value: £0.6m

Contract: ICE Conditions of Contract 7th Edition

Excavation and installation of temporary works to enable the placing of three no. full retention interceptors.

 

The scope of the work covers the installation of three no. new Class 1 full retention interceptors, (Condor Environmental Solutions CNS200s-7.53X4M diameter) together with modifications to the existing surface water and foul water drainage pipe work along with the upgrade of the bund sump pump discharge system. The work comprised the following:

• Earthworks excavation 10x14x6m deep and of installation of sheets and frames
• Installation of three no. Interceptor tanks and surround with concrete whilst removal of false work
• Over pumping throughout the operation to maintain the existing drainage system
• Excavation and installation of 41m of 600mm pipe, 56m of 225mm pipe, 27m of 450mm pipe, 146m of 150mm pipe, of which 75m was foul
• Eight new chambers and alterations to seven existing chambers
• The construction of inlet and outlet chambers
• Various ducting and draw pits

 

Eighty percent of the pipe lines were installed in the yard area of the fuel farm. This is a busy area with the constant movement of refuelling vehicles. The pipes were installed so as to cause as little disruption as possible. A key challenge was the excavation for the interceptors. A 30-tonne excavator was used for the added reach. As there was no access along the northern edge of the excavation the sheets were over driven on the south edge to enable the excavator to track into the dig area. One other challenge was the interface between the inlet and outlet chamber construction and the concrete surround whilst removing of the main excavation temporary works.