www.nce.co.uk | NEW CIVIL ENGINEER SEA DEFENCES: PEVENSEY 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 Sussex 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 Pevensey Levels, 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 fo n.in wetlands 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 EASTBOURNE Harbour or other defence structure. Here we don’t. We’ve said: ‘There’s 300 LONDON 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 Brighton storm events. Hastings 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 fo we were being paid for something Agency’s permissive powers, the PFI residents have told Thomas they n.in wetlands 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.