What they will see, however, is a surface building - containing offices and control rooms - designed to resemble the many Napoleonic forts that are spaced along the English Channel coast, along with the Martello defensive towers, built in the early years of the 19th century to protect the nation in the wars against France, which came to an end with the English victory at Waterloo in 1815.
The WTW history is necessarily shorter. In the 1960s, a modest pumping station was built on the site to deal with wastewater in the manner current at the time - essentially untreated, and pumped along outfall pipes reaching ever further from the beach. This station had been upgraded and improved by piecemeal alterations until 1993, when a major scheme was initiated to introduce significant levels of water treatment to the site.
Recognising the high amenity area of Eastbourne as a tourist town, the 1993 improvements were undertaken underground - or rather what, at high tide, would have been underwater. Two hundred piles were sunk to bedrock, and a concrete box the size of a football pitch was constructed immediately behind the shingle bank which forms the high tide barrier. The function of the piles was to prevent the concrete box floating at high water. When the installation was completed, the concrete box was roofed over, and the area became a car park.
Underground, dirty water came in, was screened to remove debris, grit, and rags, and flowed into one of six Johnson Lamella separation units, designed to remove 50 per cent suspended solids and 20 per cent of the BOD (Biological Oxygen Demand). The six units - used mostly as five plus a 'spare' - were supplied and installed by Vexamus, the Cambridgeshire based UK agent for Nordic Water Products.
When it was constructed, Eastbourne was the largest lamella installation in the UK," claims Roger Clark, process director at Vexamus. "At this works the feed to the lamellas can be dosed with a coagulant and the feed then enters the lamella via a flocculation tank.
"The main advantage of the lamella unit is its space saving. It can reduce the footprint area of an conventional clarifier by as much as 90 per cent. The plates are inclined at 55 degrees to the horizontal, and separated by spacers appropriate for the application. Feed into the lamella plates is via slots in their side walls - not under the plates like many of our competitors. This allows the sludge to fall from the plates to the base of the tank in a quiescent zone."
After treatment, water was pumped 3.2k (2 miles) out to sea.
Whilst effective, and enabling Eastbourne to maintain high standards of sea and beach cleanliness, in 1998 the UK Government and European Union reclassified the Channel and the new standards for water cleanliness meant even more effective treatment was required.
In summary, this has involved replacing three of the lamella units with biological secondary treatment; agreeing new standards for storm flow water; improving the means for dealing with solid waste; and attention to smells and other external impacts from the site. Work was undertaken by Biwater who also took over operation of the site during the main construction - and two years, and £22 million later, Southern Water took over again to the agreed schedule. Now only concluding surface works remain to be concluded.
"What we have now is a process which starts with the preliminary screening," says Andy Taylor, Southern Water's assistant project manager on the site. "This uses new and upgraded screens to remove rags and paper. Then grease and grit tanks take those elements out. We only have three lamella units now, but after them we now have a new Biological Aerated Flooded Filter (BAFF) treatment.
"It's the first time we've used a BAFF plant at a major Southern Water WTW, and it works with millions of tiny beads made from recycled plastic bottles. The beads host millions of microscopic bacteria, and float in a series of compartments in large tanks. They work by removing organic pollutants from the water flowing from the lamellas, before it is pumped out of the same long sea outfall."
The new plant has a design window of 15 years - but has removed half the lamella capacity installed in the mid-1990s. How can this work?
"It shows just how well they've performed," says Taylor. "We can use them in conjunction with the BAFF plant to achieve a certain percentage reduction on BOD. The less the lamellas work, the more the BAFF plant has to do, and vice versa. There was lots of spare capacity before with six tanks, and even now we have just three, we can think of it as two and a spare. And then of course we can always increase their efficiency by varying the chemical dosage - but, significantly, we have not proportionately increased our use of chemicals since we introduced the BAFF plant.
"As well as further improving the quality of our outflows, the BAFF plant shares with the lamellas the advantage of compactness. The space under the car park was limited - it couldn't practically be extended - so something had to go. The results prove that Biwater got their sums right!"
More significant is the arrangement with the Environment Agency over storm flows. Before the new arrangements, virtually every drop of water passed through the lamellas. Now it is accepted that in cases of exceptional storm flow, the volume of solid waste hardly changes, while the overall volumes increase dramatically. Now the full screening-lamella-BAFF process is reserved for predicted maxima under normal conditions. The extra, under storm conditions, is largely rainwater and this is screened, then passed through the grit and grease tank, then pumped from there out to sea via a medium outfall, 1.7km (just over 1 mile) long.
Input levels are also being reduced through sealing the sewerage system in areas close to the sea, to help reduce the amount of saline ground water leaking into the system. This removes water which takes up unnecessary treatment capacity, and the saline levels can adversely affect the effectiveness of the new biological processing.
Solid waste comes from centrifuged sludge, producing 25 per cent dry solids which are pumped to sealed skips and taken off site to be turned into agricultural fertiliser.
Smells are comprehensively dealt with - indeed they need to be; in recent years the plant has become neighbour to a new development of quality housing literally just across the street. The shingle shoreline forms a boundary of the site, and as mentioned above, the roof is a public car park. Below ground, the air in the process chamber is pumped to change four and a half times an hour; the foul air is passed through a two stage scrubber before being returned to the atmosphere, with a pollution level generally lower than 1 part per billion - too low for measurement.
Smells are comprehensively dealt with - indeed they need to be; in recent years the plant has become neighbour to a new development of quality housing literally just across the street. The shingle shoreline forms a boundary of the site, and as mentioned above, the roof is a public car park. Below ground, the air in the process chamber is pumped to change four and a half times an hour; the foul air is passed through a two stage scrubber before being returned to the atmosphere, with a pollution level generally lower than 1 part per billion - too low for measurement.
The visual impact of the development has been addressed through the exterior design - and the impact of the improvement works was minimised by limiting working hours to between 8am and 6pm. And - a final impressive touch - all the demolished and dismantled material, and all new material and equipment went into the concrete box processing chamber through a 4m by 3m roof opening, so as not to compromise the use of the car park by closing off sections and removing the chamber roof.
The end result? A wastewater treatment works that is in every respect a good neighbour - co-existing with premium seaside housing; and helping to keep beaches and overall water quality at least up to stringent European standards.
