First artificial surf reef in northern hemisphere built in Bournemouth

The only artificial reef in the northern hemisphere has been constructed in Bournemouth to encourage surf-seeking tourists to the south-coast town. Steve Menary donned his wetsuit to discover how contractors orchestrated the swell.

For project managers and site agents throughout the UK, another wet summer was a major obstacle to keeping work on schedule.

Many sites would have resorted to pumping out flooded footings but that is not an option for the team building Europe's first man-made reef off the south coast, as it would have meant trying to siphon off the Solent.

The project is only the fourth artificial reef in the world and the first in the northern hemisphere. There are two reefs in New Zealand - at Opunaki and Mount Maunganui - and another at Narrowneck in Queensland, Australia.

All three have been designed by specialist ASR, which, on the world's fourth artificial reef at Bournemouth, is also in charge of construction. That is a big commitment for a business based in Raglan, a two-hour drive south of New Zealand's biggest city, Auckland.

"We've brought the equipment we can, including the pumping machine, which we designed ourselves, but had to source a lot here," says David Nielson, ASR construction manager and one of nine people from New Zealand working on the scheme.

The reef project is part of a wider regeneration project in Bournemouth aimed at revitalising the suburb of Boscombe. Built for Victorian holiday-makers, who would promenade along the pier, Boscombe Spa - as the area became known - had fallen into disrepair. Many hotels had been converted into bedsits and the area has problems with drug takers.

The council put together a Neighbourhood Management Pathfinder Regeneration project, valued at £10m, and is providing luxury beach huts designed by designer Wayne Hemingway and his wife Geraldine, a lifeboat station, hot showers, and a 169-home residential scheme from Barratt called Honeycombe Chine with views of the sea.

Raising funds

Selling a local authority car park over-looking Boscombe to Barratt helped raise funding for the project, including the reef, which Bournemouth Borough Council hopes will produce an extra £3m a year in income for the town.

Public speculation about the project has been rife and ASR director Shaw Mead says: "Expectations need to be managed with this project. We are not building a wave pool that generates so many certain sized waves per hour. We are modifying the sea-bed to make the waves break better for surfing where there is swell."

Nielson has got used to outrageous claims about the project, including one that suggested the reef would generate waves of 75m high. "That's a tsunami," he laughs.

"The reef is being built for winter surfing and the Atlantic swells that break on to the beach. At the moment, there isn't a consistent wave and there's no barrel. The reef won't make much bigger waves, maybe 15% or 20% bigger at most, but it will make the waves more consistent and break where we want them to."

The reef, which will be 1ha (2.5 acres) in size when completed - about the size of a football pitch - and is sited 225m from the shore, is made up of two layers. One layer will raise the sea floor and the other will shape the waves.

There are five pieces of the reef and each section is being built on geo-textile sandbags that are, in some cases, up to 70m long and 6m wide. Manufactured by Australian company ELCO, the sandbags are attached to a webbing base produced by New Zealand supplier Unique.

Assembling sections

The sections are being assembled along the Dorset coast at the home of subcontractor Jenkins Marine and folded down to 50m x 7m rectangle and loaded onto a barge, which motors along to the site.

The reef sections are pinned to the floor of the Solent using anchors but ASR was not able to use piling to attract them. Nielson adds: "We're using 5t and 10t concrete blocks to secure the anchors. It would have been ideal to put in piles but that would have been expensive and not flexible if you need to make adjustments."

Earlier this year, thousands of tonnes of sand was dredged from the floor of the Solent near the Isle of Wight to fill the bags. The sand had to be screened for flint from the sea-bed and was then dumped on three groynes at Boscombe for ASR's team to use.

Once each section had been secured to the sea floor by divers, a 300m pipeline was pulled out and attached to another smaller more flexible pipeline and then into each geo-textile bag. Pumping then began.

This method is different to the previous reefs designed by ASR, which involved simply dropping sandbags onto the sea floor. "That's like dropping bricks into the ocean and not very accurate," says Nielson.

With ASR in charge of construction, the company opted for this new, more accurate - but more expensive - method and anticipated good progress during the English summer.

The reef was due to be completed this autumn but the weather is a persistent problem for the diving teams, which are comprised of five people with one diver going down for up to two hours at a time to secure the anchors, bags and pipelines.

In the currents

Nielson adds: "There are strong currents of up to 2.5 knots. We can pump in the rain and if the wind is coming from the north, that's fine as the sea is as flat as a pancake. But if the winds come from inland and the south or south west they are too strong. If the wind speed is much above 10 or 12 knots, we can't work as there's too much chop."

When the weather allows work to start, ASR's team works 16-hour days but those days are too infrequent. ASR had hoped to be working on the last couple of the five sections by mid-September but due to the weather, only one section had been installed by this time.

Sea life, including squid, were teeming over this section within a few days. Only the weather forecasters know when the first surfers will be able to use the reef, but Nielson hopes to be done by Christmas.

Divers go down for up to two hours at a time to secure anchors, bags and pipelines.

Project factfile

• Project: Artificial Reef
• Location: Bournemouth
• Value: £2.68m
• Client: Bournemouth Borough Council
• Marine plant hire: Jenkins Marine
• Screening subcontractor: Ram Plant
• Design and build contractor: ASR