Margate & Broadstairs wastewater treatment scheme

The final pipelines will be used to transport sewage from Margate to a treatment plant in Wethelees and then return the treated effluent to Margate where it will be discharged into the sea via a 600 meters tunneled sea outfall.

Costain is using a 3.3 meter-diameter Lovat ME131SE TBM to build tunnels comprised of ID2.9 meter rings of 6-piece trapezoidal precast reinforced concrete segments.

The first section, the 640 metre Sloe Lane tunnel, began in late October, 2005 was completed January 17th, 2006. The TBM was removed and lowered into another one of Costain's 9 meter-diameter shafts at Broadley Road. On July 7th, 2006 the TBM completed another 1,400 meters for the Princess Margret Avenue tunnel. The tunnels feature 250 meter-radius curves. Both tunnels were completed ahead of schedule.

Costain is operating the TBM with a twelve-hour day shift (no night shift) with a reported best day of 28 No. 1 meter-long rings.

The tunnel alignments are all above the water table. The geology consists of chalk with flints.