Ipswich Icons: Project Orwell brought much-needed sewerage to the town

Toller Road large diameter shift

Toller Road large diameter shift - Credit: Archant

This week’s article is written under a false premise. I very much doubt if you have ever seen this ‘icon’ and you almost certainly never will, but it is an essential bit of kit contributing quietly to the well-being of Ipswich, writes John Norman, of The Ipswich Society.

The Round Pond in Christchurch Park

The Round Pond in Christchurch Park - Credit: Archant

Ipswich was late introducing public sewers and although Peter Bruff (of Eastern Union Railway fame) was commissioned to design a drainage system in 1857 it wasn’t until 1882 that the low level trunk sewer was constructed. The reference to ‘low level’ implies across the lower part of the town centre, Bramford Road to the Wet Dock and on to Pipers Vale (the site of the present day water treatment works).

In 1927 civil engineer Edward McLaunchan designed a modern sewage system and treatment works (completed in 1932). A key component was the high level sewer which ran from Norwich Road through the town centre and then across the Suffolk College site to the new sewage works.

McLaunchan promoted a scheme with a final outlet into the Orwell that would not leave solids on the river bed or cause offensive odour. It proved to be a very efficient system, but it wasn’t designed for, and couldn’t cope with, sudden surges caused by heavy downpours. In such conditions the system simply overflowed, into the Orwell, into the Gipping, and occasionally into the street.

By the end of the 20th Century the town’s sewers couldn’t cope in times of heavy rain. They were perfectly adequate for the everyday sewage but because Ipswich has a combined system (both rain water and foul discharge into the same drain) when a major storm deposited substantial quantities of water in a short time the sewers overflowed, and the mix of rain water and sewage spilled into gardens and low lying areas.

Alexander Park - south end

Alexander Park - south end - Credit: Archant

In the 1990s a European Urban Wastewater Treatment Directive instructed all water authorities to make changes to stop this happening. In Ipswich the solution was Project Orwell, a deep level large diameter sewer from Bramford Lane allotments along the line of Norwich Road, Anglesea Road, under Christchurch Park and then sweeping a slow curve to Alexandra Park and Duke Street to Toller Road.

All of the major sewers the new tunnel passed under were allowed to overflow into it thus in times of great storm the new tunnel simply held a vast quantity of water until the storm had passed, water that was then pumped (usually overnight) to the treatment works.

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Project Orwell started in January 1998 with a large round hole, a vertical shaft on a site adjacent to Toller Road. A tunnel boring machine or TBM, affectionately named Athena by the guys on site, was lowered into the hole and slowly but surely dug her way the 5km to the west side of town. She drilled a 2.5m diameter hole through soft chalk some 20 metres down, pulverised the chalk with the lubricating water and pumped the resulting slurry back along the tunnel. This was then carted away for use as an acid neutraliser on local farmland.

Athena was followed along the bore by a railway line, an ever- increasing length of single track which was used to deliver tunnel linings, additional track and men to the workface. The narrow gauge railway didn’t last long; as soon as the TBM reached its destination the track laying process reversed and all signs of the railway were removed leaving a smooth bore, clean-lined tunnel with nothing to hinder the flow of water.

In addition to the tunnel six vertical shafts were constructed to act as additional storage capacity, each has a vent about the size of a lamp post which is the only visible sign of the vast construction project below the surface.

Civil engineers Amec completed Project Orwell in March 2000, in total it had cost Anglian Water £33 million but had provided relief from the unpleasant flooding that some residents had increasingly suffered.

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