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SEA DEFENCES: BAY

the sea change in saving uk coastlines

The world’s only t first glance the beach The agreement was signed in situation worsening, and major at Pevensey Bay looks 2000 as a way of bringing much investment was needed to PPP/PFI sea defence typical of many on the needed investment to Pevensey restore the shingle bank to an contract this year AEnglish Channel coast: Bay, where the only protection effective sea defence structure. a constantly shifting landscape against flooding was a naturally But, with money tight for the celebrates its 10th of shingle interspersed with tim- formed shingle embankment. A necessary capital expenditure, ber groynes in varying states of permanent breach would result the Environment Agency looked anniversary of disrepair. But closer inspection in 50km2 of land being flooded at at alternative funding through protecting East reveals that this 9km stretch of high tide – an area that includes partnership with the private East beach is far from over 17,000 properties as well as sector, and in 2000 awarded a Sussex from coastal typical, not least because it is roads and railway lines. 25-year contract to a consortium flooding. Margo the location of the world’s only The Environment Agency of Westminster Dredging, Dean PFI/PPP sea defence contract. estimated in 1997 that the cost of & Dyball, Mackley Construc- Cole talks to some of The contract runs for a 25-year a permanent breach at Pevensey tion and Mouchel to restore period, and this year the two would be £125M. Also affected and maintain the beach to the the key players in the sides – client the Environment would be the , an required levels. arrangement to find Agency and the four companies important wetland environment With a value of around £30M that make up the PPP consor- designated as both an SSSI and over 25 years (at 1999 prices), the out what has made tium – are celebrating their 10th a Ramsar site. PFI is fairly small in comparison it such a success. anniversary in an atmosphere The bay’s defences have with more typical contracts for of mutual accord. Environment suffered scant maintenance, as roads, schools and hospitals. As Agency team leader Ian Nunn well as being affected by natural a result, the four firms were able describes the arrangement as erosion. By the late 1990s many to finance the PFI themselves, “pretty much perfect”, adding: of the beach’s 150 groynes had rather than borrowing money. “People just didn’t believe you reached the end of their useful At the time of the appointment could run this sort of project on life and a 1 in 20 year storm may they created a special company effectively trust, but in 10 years have seen the embankment fail. Pevensey Coastal Defences the dispute and compensation Routine maintenance alone (PCDL) to deliver the contract. clauses have never been used.” was insufficient to prevent the In simple terms the NEW CIVIL ENGINEER | www.nce.co.uk

SEA DEFENCES: PEVENSEY BAY

“We’ve committed 1 mile to protecting Sussex N PEVENSEY BAY, 2 km from a one in 400 Pevensey SEA DEFENCES event. That’s the Wetlands contract, and it’s up to strategy Urban areas Beach maintenance activities us how we do that” Roads Ian Thomas, PCDL Rail PEVENSEY LEVELS A259 SSSI and Ramsar - BEXHILL-ON-SEA designated freshwater

wetlands n.in fo to es ­consortium has been contracted

Cooden .paulw to provide protection against a 2 A259 breach of the shingle bank for 35km any storm with a joint return period of one in 400 years or graphic: © www A27 Cooden Beach less. As PCDL project manager Ian Thomas – based perma- PEVENSEY Normans Bay LITTORAL DRIFT nently at Pevensey – puts it: pushes shingle west to east “We’ve committed to protecting along the coast eroding the Sussex from a one in 400 event. natural beach defence That’s the contract, and it’s up to Pevensey us how we do that.” Bay Nunn adds: “In a normal sea 9km beach front maintained defence contract we would still own the risk of the concrete wall, Sovereign Harbour or other defence structure. Here we don’t. We’ve said: ‘There’s 300 your beach – you manage it’.’” homes built on the beach PCDL has three strategies: Langney improve the defences to the Point required standard; maintain the improved defences; and respond Bexhill-on-Sea when the shingle is disturbed by storm events. ENGLISH CHANNEL The initial work to raise Pevensey the standard of the defences Eastbourne required importing 200,000m3 of shingle dredged from banks at nearby Hastings and Little- hampton. With the shingle bank restored the plan was then to 1. UNDER THREAT 2. REPLENISHMENT 3. RECYCLING 4. REPROFILING gradually create a more open beach by removing most of the existing groynes as they became unsafe. It is likely only six will eventually remain, located at strategic points along the shore. Pic box Pic box Pic box Pic box But without groynes the shingle can work its way to the north-east end of the bay and be lost. In fact, this is part of the plan as the next section of coast at Bexhill-on-Sea depends on If the shingle bank had not been At the start of the contract After a storm PDCL collects shingle One bulldozer stays on site this littoral drift for its shingle restored a breach could have 200,000m3 of shingle was brought that has been moved by the waves throughout autumn and winter supply. So PCDL’s contract flooded 50km2 of land, 17,000 in to build up the defences. Now and returns it to the section of beach to carry out day-to-day reprofiling. includes a provision for at least properties, caravan parks, roads every year the beach is replenished it came from. If this is done quickly But if the shingle profile changes 16,000m3 of shingle to move onto and railway lines. Also at risk were by a specially commissioned dredger enough the shingle does not after a bad storm the contractor has that frontage every year. Add to the Pevensey Levels, an important taking shingle from nearby banks dissipate over a wide area, and can to mobilise whatever plant this the amount that is lost to SSSI and Ramsar-designated and depositing the material at the be easily collected, returned and necessary to start restoring the sea, and, as Thomas says, “we wetland environment western end of the bay placed by bulldozer original shape within one tidal cycle have to provide a minimum of 20,000m3 of shingle every year just to stand still”. In addition to this annual 3 3 replenishment, however, PCDL 17,000 200,000m 2M.m 12 hours also recycles the shingle while properties at risk of flooding initial shingle replenishment volume of shingle on beach maximum mobilisation time it is on the beach. After a storm, shingle can be lost from particu- www.nce.co.uk | NEW CIVIL ENGINEER

Keeping the neighbours happy 1 mile N PEVENSEY BAY, 2 km “I think this is a partnership not beach at Pevensey Bay is not owned the use of heavy plant. “Reprofiling just between us and the client by a single landowner or authority. has to happen at low tide, so we Wetlands but between us and the local Instead, there are 300 properties often tend to be working at 6am, SEA DEFENCES community,” says PCDL project built directly on top of the shingle meaning residents could be woken Urban areas manager Ian Thomas, who is bank, each with ownership of their up by a bulldozer,” explains Thomas. Beach maintenance activities Roads based permanently at a small beach frontage as far as the mean From the start, the team has Rail office behind the beach. high water line. encouraged local residents to visit PEVENSEY LEVELS A259 Despite being able to undertake Thomas in his beachside office. This “We thought at the outset that, as the work under the Environment “open door” policy has worked, as SSSI and Ramsar - BEXHILL-ON-SEA designated freshwater we were being paid for something Agency’s permissive powers, the PFI residents have told Thomas they wetlands n.in fo to not to happen, we needed to be consortium is aware of the need no longer need specific stakeholder es more proactive in terms of liaising to be as sensitive as possible to meetings that used to be held on a

Cooden .paulw 2 A259 with people and how we were these landowners and other local regular basis, because they already 35km presenting ourselves.” residents, especially as the shingle know what is going on, from their Unlike many coastal zones, the replenishment and recycling involves day to day contact with Thomas. graphic: © www A27 Cooden Beach PEVENSEY Normans Bay LITTORAL DRIFT larly volatile areas, but the Both sides believe the PPP just the coarse elements to the company has discovered that it contract encourages innova- widened crest and leave the sand pushes shingle west to east along the coast eroding the does not initially move very far. tion, with the 25-year timescale lower down on the beach. natural beach defence If this shingle is collected soon allowing PCDL to try new tech- By 2004 PCDL had deter- after it moves, it can be returned niques and refine its methods. mined that minimal amounts of Pevensey Bay quite quickly and easily (and Evidence of this can be seen in sediment were lost offshore, and 9km cheaply) using dumptrucks. the way the company now carries so refined the process allowing beach front maintained Unlike traditional PFI out the annual replenishment in it to dispense with surveys for Sovereign contracts, the Pevensey arrange- which 20,000m3 of new shingle measurement purposes. EASTBOURNE Harbour ment could be seen as “paying is deposited on the beach. Completion of the Sovereign for something not to happen”. In the first year PCDL used Harbour development at the 300 LONDON homes built on the beach Over any 25-year period – the a 5,000t dredger to offload into west end of the bay meant the Langney length of the PFI agreement – it two barges that bottom dumped company had to deposit shingle Point is highly unlikely that defences it at the base of the beach at high in front of a rock revetment, capable of withstanding a one tide. The shingle was recovered and since 2008 has used this Bexhill-on-Sea in 400 year flood will ever be at low tide and placed with an as a chance to experiment with Brighton fully tested, making it difficult to excavator and bulldozer. simply using the dredger and Hastings measure whether PCDL has done A year later the efficiency of one bulldozer to place the mate- ENGLISH CHANNEL Pevensey what it was contracted to do. But the process had been improved, rial. It soon became clear that Eastbourne the two parties have agreed a set because Westminster Dredging the annual beach replenishment of “key physical features” that had commissioned a new could be carried out at this one define the required defences, with dredger, Sospan Dau, so that the location alone, and that wave monthly payment based on the shingle could be “rainbowed” action would naturally disperse beach meeting these criteria. directly from the vessel onto material further east. The two core requirements are the beach on the high water “This is the dominant transfer 1. UNDER THREAT 2. REPLENISHMENT 3. RECYCLING 4. REPROFILING that there should be 2M.m3 of line. This not only meant the direction, and very quickly it shingle distributed over the 9km shingle was closer to where it starts to move along and up the long bay, and that the shingle was required, but also avoided beach, without any cliffing,” bank should have a minimum the need to wait for the tide to go width of 22m at its crest. fully out – and the risk of losing To ensure the beach has a some of the shingle by tidal Pic box Pic box Pic box Pic box roughly even spread of shingle, action. It also eliminated the it has been subdivided into need for dump trucks. 53 sections, and the required This method also had the volume and acceptable recession advantage of almost eliminating rate stipulated for each section. “cliffing” – the tendency for “We compare the volumes on a the shingle bank to form steep If the shingle bank had not been At the start of the contract After a storm PDCL collects shingle One bulldozer stays on site monthly basis to the contract “cliffs” once it is attacked by restored a breach could have 200,000m3 of shingle was brought that has been moved by the waves throughout autumn and winter volumes and tolerances,” waves. The phenomenon occurs flooded 50km2 of land, 17,000 in to build up the defences. Now and returns it to the section of beach to carry out day-to-day reprofiling. explains Thomas, who uses a because sea-dredged aggregate properties, caravan parks, roads every year the beach is replenished it came from. If this is done quickly But if the shingle profile changes GPS system mounted on a quad introduces more sand into the and railway lines. Also at risk were by a specially commissioned dredger enough the shingle does not after a bad storm the contractor has bike to survey the entire beach beach crest than occurs naturally. the Pevensey Levels, an important taking shingle from nearby banks dissipate over a wide area, and can to mobilise whatever plant once a month on the Spring tide. When subject to wave action, the SSSI and Ramsar-designated and depositing the material at the be easily collected, returned and necessary to start restoring the Individual readings are verti- higher sand content allows the “We compare the wetland environment western end of the bay placed by bulldozer original shape within one tidal cycle cally accurate to within ±30mm, material to stand much steeper which means 2M.m3 of shingle than naturally sorted sediment. volumes [of shingle] can be measured to an accuracy The resulting cliffs not only make on a monthly basis to of ±10,000m3. it difficult to walk on the beach, 3 3 This monitoring also gives the but can also collapse. the contract volumes 17,000 200,000m 2M.m 12 hours company vital information about But during the rainbowing and tolerances ” properties at risk of flooding initial shingle replenishment volume of shingle on beach maximum mobilisation time how the beach behaves, and how process the sand tends to migrate Ian Thomas, PCDL the shingle moves tide by tide to the fringes of the mound, and after storm events. making it possible to recover NEW CIVIL ENGINEER | www.nce.co.uk

SEA DEFENCES: PEVENSEY BAY

explains Mouchel technical is a bad storm Mackley – the that’s underneath the active beach savings. At the same time, the manager Zoe Hutchison. consortium member responsible and re-use it elsewhere,” says 25-year contract also gives the What started as an annual for maintenance and emergency Thomas. “And during a storm, entire sea defence industry a real operation involving three sea- response – mobilises enough linked bales would act as a struc- chance to learn how this beach going vessels, a bulldozer, an plant to restore the beach profile ture and not be breached.” works. “You don’t usually get excavator and a surveyor has within one tidal cycle. “If we At the moment the tyre bales the luxury of managing a stretch since 2009 been achieved with failed we would get penalised by are more of a research project of beach for a long period,” says just a dredger. The company PCDL,” says Mackley managing and are being monitored to Camilleri. “But it’s meant we’ve has one bulldozer permanently director Tony Camilleri. see how they perform in this learnt how to deal with all of the on site throughout autumn and Innovation has not been saline environment. “They’re natural processes of the beach.” winter to carry out day-to-day limited to the use of plant on the most effective where you can Both PCDL and the Envi- reprofiling work, but if there job. The team has also trialled bring them close to the site and ronment Agency believe that lesser known hardwoods for fabricate them here, so at the Pevensey has helped evolve new groynes and experimented moment they’re not being used best practice in the provision with groyne components made in earnest,” explains Camilleri. of shingle sea defence manage- “If we failed [to of recycled plastics. “They are But that could change, says ment. The team describes its respond to storm abrading less than the wood,” Thomas: “It has to be cost effec- methodology as “little and damage] we would says Thomas. “I would certainly tive for us to use it, but if shingle often”, where the key elements use them on the part of the goes up in price maybe we will are guaranteed funding, regular get penalised by groyne that’s not seen.” use them more.” monitoring, physical trigger PCDL” PCDL has also replaced a The nature of the PFI gives levels that define when interven- section of the underlying shingle PCDL and its member compa- tion is necessary, and flexibility Tony Camilleri, Mackley with tyre bales. “You can use them nies an incentive to innovate, to adjust working practices as to displace some good shingle because it may result in financial coastal processes change.

Ice age complications The PPP/PFI

While other sectors may be questioning whether PFI has ended up costing more than conventionally procured alternatives, the Environment Agency is convinced it has got a good deal at Pevensey.

“It’s difficult to clearly define what value for money the project offers, but over a 25-year period it will demonstrate its value, says Environment Agency team leader Ian Nunn. “I would challenge anyone to find anywhere in the country where less than £40M has been spent on 9km of managed defences over 25 years. “The big benefit is having guaranteed funding,” he adds. “This is the only project where we know that in 15 years time it will still be operating. It’s genuine asset management.” Nunn believes the decision The shingle that forms the beach beyond a critical point, waves So for much of the last 500 years to identify the “key physical at Pevensey Bay originally came were no longer able to continue the Sussex coast has been fed by features” of the beach as from the seabed. delivering sufficient sediment, and littoral drift alone, and there is no the basis for payment is vital littoral drift became the dominant longer enough sediment in the to the success of the beach As water levels rose since the end force, as wind and waves combined system for them to survive without management strategy. of the last ice age, and the English to move shingle along the coast intervention. “We’re understanding more Channel formed and expanded, faster than it arrived. Pevensey is typical of the area, and more about the way the wave action gradually moved glacial Initially a feed of material was losing 20,000m3 every year. beach reacts to what we do and and other debris towards the land. maintained, with the shingle Without intervention the defences the operations we carry out, This process continued unabated for coming from the large beaches would not have lasted long before “One of the big benefits of thousands of years, depositing formed during times of excess they would be breached, and this contract is that it gives the large amounts of aggregate on supply. But these gradually eroded, the annual provision of new contractor time to evolve best the foreshore. and once they had gone many marine aggregate is critical for practice. It avoids short-termism,” But once water depths went beaches faced destruction. the beach’s survival. he says.

Pevensey Coastal Defence Limited