18 Oct 2005
A series of lateral sewer connections, achieved by Perco as part of the Environment Agency’s flood alleviation project for Lewes, have set a UK precedent in augerbore trenchless technology.
The augerbore team operated subcontract to Costain B&V JV and worked with Oxford Hydrotechnics to overcome unstable ground conditions, made worse by the high water table in the area. The contract required four drives, totalling 150m in length, at three locations. At Court Road, the launch points were from a new 1200mm concrete pipe, 13m below ground level and approximately 1.5m below the water table.
Perco used a BM150 DT rig to produce a near vertical bore, through the chalk ground, for the lateral drain. The augerboring rig was lowered via a shaft to the new sewer pipe and moved 40m on rollers to the first launch point. Here, the pipe wall was drilled for resin injection into the surrounding soil and diamond-cut for the augerbore. Even without optical guidance, the accuracy of the drive was perfect.
Perco inserted MDPE pipe in threaded, short lengths, before removing the auger casings and fitting a 45 degree bend onto the pipe. The process was repeated to install a second lateral connection.
The existing 25” cast iron rising main carries sew...
Perco - Specialists In Trenchless Technology
