Going back in history, back to the 1850s, Brighton was a little fishing village, no different to any of the other small fishing villages along the South Coast,” explains Ben Green, senior project manager on Southern Water’s Wastewater Treatment Scheme to bring cleaner seas to Sussex. “There was a doctor who lived in Brighton, Richard Russell, who wrote a dissertation on the beneficial effects of seawater. It quickly became a best seller and popularised Brighton as a seaside resort.”

Green continues, “The problem was, at that time, most of the city wasn’t served by a formal drainage network. There was some sort of surface water and sewerage management system, but that just took the wastewater out and discharged it on the beach, which wasn’t ideal when people were bathing in the sea.”

More than a century and a half later wastewater management is once again a major issue in the city of Brighton and Hove and surrounding villages and towns, hence Southern Water’s GBP 300M (USD 467.2M) environmental improvement scheme, whose slogan proudly boasts, “We’re bringing cleaner seas to Sussex.” The main part of the scheme is the construction of a new wastewater treatment works and sludge recycling centre in the East Sussex seaside town of Peacehaven, about 10km east of Brighton, which will treat the 95 million litres of wastewater generated each day by the residents of Peacehaven, Telscombe, Saltdean, Rottingdean, Woodingdean, and the city of Brighton and Hove. In addition to the works, some 11km of tunnels are being constructed to transfer wastewater to the new treatment works, and then cleaned wastewater from the works to a new 2.5km long sea outfall pipe.

The new scheme has been a long time coming, as the city currently still relies on a system developed by one of the great Victorian engineers Sir John Hawkshaw, who was commissioned to the job in the 1860s after a long political debate between the sanitationists, who wanted taxes to be raised and a new system developed, and the anti-sanitationists, who just wanted to extend the various outfalls further out to sea.

“The current system is a sewer pipe that runs along the coast down to the Portobello pumping station at Telscombe Cliffs [between Brighton and Peacehaven]. The flows receive only the basic treatment before being pumped out to sea through a 1.8km outfall pipe. The sewer pipe was dug by hand in chalk in the 1860s.” explains Green.

The surge in investment in the water industry over the last two decades has been driven mainly by the establishment in the early 1990s of the Urban Wastewater Treatment Directive (UWWTD), which requires various standards of treatment in relation to population size. As part of the UWWTD, Brighton and Hove requires treatment of the wastewater to secondary standard. Another reason the city needs a new scheme is that the Victorian system was only designed for foul flows and not surface water or storm flows, meaning that right up until the 1990s all the storm overflows used to just go into the sea. This led Southern Water to construct Europe’s largest wastewater storm tunnel, 6m in diameter and about 3 miles in length (4.8km), underneath Brighton beach, which serves as a storm water holding tank.

New sewerage works
Brighton and Hove’s new sewerage system is being delivered by 4Delivery, a joint venture consisting of Costain, United Utilities and MWH. The 11km tunnel will start at Brighton Marina and follow the A259 coast road eastwards, first to the pumping station at Marine Drive, and then along to Portobello, where it will be pumped up once again. From Portobello the waste will be sent further eastwards down the remaining section of tunnel to the new treatment centre. A gradient of 0.2 per cent will convey the waste through the tunnels. Green explains the reason for using pumping stations is to ensure that the tunnel depth isn’t excessively deep and remain for the most part above the water table and sea level.

Two 2.44m diameter TBMs will create 9km of tunnels, with pipejacks driving a further 2km. Both TBMs have rippers with carbide facings to decrease the wear. “Costain expects these rippers to last through most of the drive lengths, without replacement, 1,600m. Flints are expected along most of the drive lengths but the rippers are expected to dislodge the flints out of the chalk matrix rather than break them up,” says Southern Water spokeswoman Madeline Stoneman.

Each TBM, Alice and Hollyblue, are handling two drives. On the west side of the project the TBM is boring from the Ovingdean shaft westwards to the Marine Dive shaft. The machine will be taken out of the Marine Drive shaft, dismantled and returned to Ovingdean. Here it will bore eastwards to the Portobello Pumping Station shaft.

A huge barge, the Nordic Giant, has already dug the seabed trench into which the new outfall will be placed. Costain’s project manager (infrastructure) on the job, Craig Reade, explains, “we’re looking to achieve between 10m and 40m a day in full production. The geology is essentially chalk, with some flint inclusions and possibly some seams, but nothing too challenging.”

Advance rates at Ovingdean are approaching 40m per day (two 12 hour shifts) though it is hoped that this can increase to 60m per day. Excavation time for a 1m advance is around 10 minutes.

On the east side of the project the second TBM is boring from the Peacehaven Wastewater TreatmentWorks site to Portobello Pumping Station. It will then be taken back to Peacehaven and launched towards the Friars Bay Head shaft.

“The Peacehaven machine, Hollyblue, has a screw conveyor and harder chalk, has slower excavation times. Rates of progress are expected to increase as Hollyblue is not yet dully launched,” explains Stoneman.

At each end of the project there is a section of pipe jacked tunnel. At the western end the works have been complicated by the proximity of the surrounding buildings and the stability of the cliff.

The Marine Drive Shaft is the meeting point for the TBM driven stretch from Ovingdean and the pipe jacked section from the Marine Gate Shaft.

“The site’s almost 50m deep, 20m diameter shaft. It’s also got a reception shaft to accept the 2.4m diameter TBM, which is currently on its way from the Ovingdean site and is about 300m in, due to come out in mid-October,” says Green. At the Marina site much of the cliff is chalk but some is wave deposited sands and gravel. Green says, “It’s actually a raised beach. Apparently, in glacial times this was all just wave deposited sands and gravel up against the cliff, you can see the profile of the chalk, so we’ve had to take particular care here to make sure that the workforce is safe underneath that cliff.We had to monitor it every day as we worked to enlarge the chamber round the existing structure.

“We’ve actually amended the access route here.We’ve built an additional access route round the back of Asda because we didn’t want to bring in all the construction machinery and the TBM through a busy car park with lots of pedestrians,” says Green.

“It’s taken us ten years to get the planning permission, and to get the permission we’ve made a lot of commitments to a lot of people. Being a considerate constructor was a fundamental part of that. So when Asda said, ‘we would prefer that the access is not through the site, can’t you put an access route to the rear?’ that’s what we did.”

The tunnels will be lined with a 2.44m i.d tapered trapezoidal ring consisting of six segments. These segments are cast using steel fibre concrete. Each ring is erected behind the TBM and grouted in place using a PFA/cement mix.

At each end of the works there are sections of pipejacked tunnel of 1.8mi.d. These pipes are formed of reinforced concrete.

Pumping stations
The first pumping station, situated at Marine Drive and with a 16m vertical lift, finds itself in a strange position. Green explains, “the only place we could get planning permission and all the land in order to build the pumping station was effectively through the middle of a traffic island in the middle of the road. But it’s actually quite a strategic location.”

He continues, “It’s a place where the road opens up to two lanes going in to Brighton. So the council was keen to have a landmark gateway structure; they didn’t want a standard pumping station. You’ve also got your million pound houses just above, and the residents didn’t want their view spoiled, so the pumping station is actually set down into the road. There was an architects’ competition to design the building over the top—the winning design has a zinc roof, Portland clad stone walls, and a stainless steel handrail. It’s quite a weird shape, it’s shaped like a fish or an eye, and it will hopefully be a landmark gateway feature to the city of Brighton that people will like and recognise.”

The second pumping station at Portobello sits down underneath the cliffs of Telscombe, and has a 13m vertical lift. The existing flows from Peacehaven currently come down into the original chamber and then out to sea through the 1.8km outfall. When work is finished they will be re-routed around to the new pumping station being built next to the old one and then further eastwards to Peacehaven. On site, Green explains, “This is the existing operational site; it’s where we take the screenings out. This was the site originally selected to extend. The works here would have been built on a platform out to sea, cutting back into the chalk a bit more, but due to the planning constraints it was not possible.”

At the same time, Southern Water tried to get permission to build a wastewater treatment works at Portobello, but planning constraints meant that was turned down both at the planning commission stage and also on appeal. A public inquiry ruled out the works on the grounds that it was a Site of Special Scientific Interest, although historically the flow has always come through to that point.

Southern Water then still had this problem of where to build the treatment works, and that problem was actively worked on over the next decade.

A shortlist of 66 sites was narrowed down to eight, and those sites underwent a strict assessment against construction, environmental need and planning. The site at Peacehaven, where the works is currently being constructed, was selected as the preferred option.

A planning application was submitted in 2005 to both Brighton and Hove City Council and East Sussex County Council because the scheme spans two administrative areas. Brighton and Hove City Council approved the plans, while East Sussex County Council didn’t determine the application resulting in a public inquiry.

The secretary of state agreed that the revised site at Peacehaven was the most appropriate location but didn’t like the look or the overall architectural design of the treatment works itself, so the scheme was re-landscaped and it also had a living green roof put on top of it to blend it in to the downland landscape. That went back to planning application and was passed. It then went back to the secretary of state to check that he was happy with it, and he was.

The objectors—and there have been many vocal and active campaigners against the scheme, due to the location being in Peacehaven—took it to judicial review in early 2009, but the judge said all the planning legislation was fine and that it should go ahead. So Southern Water eventually started construction of the current scheme in summer 2009.


One of the 2.44m diameter TBMs being lowered for launch A schematic showing the rises and falls along the tunnel length The shafts will later house pumping stations The precast segments at the Brighton worksite A plan showing type and direction of tunnelling The sewerage processing facility at Peacehaven A distant view of the treatment work A computer generated view of Peacehaven once work is completed