Brenwal were awarded the contract to reline & carry out manhole rehabilitation works to a 300mm diameter foul main located air-side at Jersey Airport, running directly under the runway. The works were carried out during night shifts, under strict restrictions on working hours when the airport was closed. The main line was over pumped to enable the relining works to be carried out. The works comprised of 300 linear meters of 300mm diameter 6mm thick UV cured liner which was then cut back and the manhole rehabilitation works carried out.
The manhole rehabilitation works consisted of 10nr manholes at various depths. The cover slabs were removed and the existing benching broken out and channel pipe. A new GRP channel pipe and GRP benching plate was then installed. A new 30mm thick GRP pipe liner was installed inside the existing manhole rings. A Fosroc HF grout was poured between the old manhole ring and new GRP liner to form a seal. New cover slabs were installed with a GRP coating to the underside. When all elements were installed the new construction joints were sealed with a GRP band and all were coated with a flow coat to give a fully structural GRP liner within the existing manhole.