The pipework is constructed in a saw tooth profile from High Density Polyethylene (HDPE) jointed using electro-fusion welded couplings and is of a diameter of between 90mm to 315mm.
The sewage in the pipework initially travels at velocities of up to 6 metres per second as a foaming mixture of liquid and air. The velocity gradually reduces as the mixture moves along the sewer and the air eventually overtakes the liquid and continues onwards towards the vacuum station causing the sewerage to come to rest at low points within the saw tooth profile of the pipework, called invert lifts.
The sewage remains stationary until an interface valve opens again on the upstream side of the invert lift allowing air to enter the sewer network. This sewage is then lifted from the low points and again transported onward towards the vacuum station.
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Interface Valve Chamber Vacuum Station