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St Petersburg flood barrier: Russia’s priceless defence

After 30 years, a giant construction effort to protect the beautiful city of St Petersburg from catastrophic flooding is drawing close to completion. Jackie Whitelaw reports on an historic civils project.

Perched on a rocky promontory out in the Neva Bay on a balmy autumn day it is hard to imagine how threatening this environment can become. And not least to the brightly painted stonework and golden spires of the Russian city of St Petersburg which glows pink in the afternoon sun at the head of the bay.

But the city is under threat, and from the same serene expanse of water that is lapping around the promontory on the island of Kotlin just a few kilometres out into the bay. Storms in the west create huge surge waves that funnel down the Gulf of Finland straight at the city.

At the worst projection the city would be flooded to a depth of 5.15m. Up to 3M of St Petersburg’s 5M inhabitants would be directly affected and some of the world’s most precious monuments would be swamped at unimaginable cost.

The gloriously, decadently grand Winter Palace completed by Catherine the Great − which was the focus for the start of the Russian revolution and which houses the Hermitage, one of the world’s greatest museums and art galleries − would be flooded up to its first floor windows.

Other city landmarks like St Isaac’s Cathedral and the Church of the Saviour on Spilled Blood with its ceramic and enamel decoration and priceless wall paintings would be semi-submerged in freezing, abrasive sea water.

“Effectively they are like two large submarines which are driven out into the channel, water is pumped in and they land on the sea bed.”

Oleg Panchuk, Ministry of Regional Development

Water and sewage treatment plants, schools, hospitals and the city’s metro would also be inundated and the people left safe after the waters had receded would be facing a humanitarian crisis to rival or eclipse that of New Orleans in 2005.

But after an extraordinary effort by the Russian government, some help from European funding and an all out assault by Russian and international civil engineering experts, none of this will happen − if the weather holds good for one more winter.

In St Petersburg it is the custom to wrap al fresco diners in soft, pastel fleecy blankets as they brave the chill autumn evenings. Currently the city is wrapping itself in its own protective blanket, in the form of a curving flood barrier that embraces the shallow waters of Neva Bay.

The project is something of an epic in scale and timeframe. The 25.4km barrier consists of 11 embankment dams, six sluices and two navigation channels each with floodgates. The dimensions are massive. Each of the pair of floating steel gates that closes like a door to shut the main navigation channel measures 122m long by 23.5m high by 4.7m wide. “Effectively they are like two large submarines which are driven out into the channel, water is pumped in and they land on the sea bed,” explains Oleg Panchuk, deputy general director for security and public relations for client the Ministry of Regional Development.

The second channel is closed by a steel barrier that rises from a concrete slot at cill level and is 118m long, 12m deep and 9m thick. It can punch through 600mm of ice − the most that would be expected in a St Petersburg winter.

The barrier also doubles as a motorway − the latest link in the St Petersburg ring road. It will carry a six lane highway that crosses one navigation channel via a bridge that lifts 9m to allow shipping underneath. It passes beneath the main navigation channel in a 2km long, 26m deep tunnel.

Something of an epic

The barrier has effectively been under construction for a heroic 30 years.

It started in 1979 under the Soviet regime, then juddered to a halt 65% complete under Glasnost and Perestroika and the break up of the Soviet state.

What was built was close to being demolished in the early 1990s when the local population took against it, seeing it as a threat to the environment of the Neva Bay.

But the project was then revived as environmental fears were allayed and concerns about climate change and rising sea levels grew.

MAIN NAVIGATION GATE NOW

The connecting arm moves each floating gate into position

With the barrier’s construction, the island of Kotlin in the Neva Bay will for the first time be properly linked to the mainland. The barrier runs from Bronka in the south to Kotlin and its main city of Kronstadt and then to Gorskaya on the northern shore of the bay.

Total cost of the project is 87bn roubles (£1.8bn). “The project is expensive,” says Panchuk “But the losses that will be avoided in the city from regular flooding will compensate for the expense. And the barrier gives an impetus for the development of new ports and industry − on Kotlin and on the mainland.

“The cost takes into account construction inflation and the cost of the motorway as well as dredging for a new, deeper sea channel to allow larger ships into St Petersburg, a new navigation system and power supplies to the barrier and the town of Kronstadt. So we are solving a huge, complex task here.”

The barrier is now something of an important project for Russian prime minister Vladimir Putin who studied at St Petersburg University and who was a senior member of the city’s administration.

Funding

Funding for the £1.8bn scheme has come from three sources.

International financing includes a £150M European Bank for Reconstruction & Development (EBRD) loan matched as a condition of the loan by the same funding from the Russian federal budget. The rest is additional funding from the federal budget.

The EBRD says the international financing “gives the Russian authorities an opportunity to demonstrate that large public sector projects can be completed in time and within budget on the basis of open and transparent procurement practices”.


On his visit last year Putin told the construction team that the original completion date of 2012 should be brought forward to the end of 2010.

You can understand the sense of urgency − as well as admire the ability to accelerate a major project.

In its 306 year history the city has been flooded more than 300 times. The most catastrophic was in 1824 when the water level rose by 4.21m; the second, 100 years later, was in 1924 when levels reached 3.6m. It has been 85 years since the last major flood.

“The frequency of flooding is increasing. So the project is not a whim, it is vital.”

Oleg Panchuk, Ministry of Regional Development

“The scheme is designed for a 1000 year flood of 4.55m but is checked against failure for a 1:10,000 year flood of 5.15m. And during construction of the barrier 20% of all the flooding in the last 300 years − 59 incidents of water level rise over 1.6m − has happened.

“The frequency of flooding is increasing. So the project is not a whim, it is vital,” Panchuk says.

Attracting the attention of the government hierarchy has its benefits − there are never any problems with the financing. But progress is watched critically and success raises expectations.

“When Mr Putin visited last year the speed of construction progress was clear,” says Panchuk. “And it was clear that the project could be finished earlier so we were told to go for it. It was not about a voluntary decision.”

Signed up to that deadline is UK consultant Halcrow which is lead designer for the flood barrier scheme.

Reassessed and updated

When the European Bank for Reconstruction & Development agreed to lend money to the scheme (see box above) there was general agreement that after a 15 year halt in construction the designs should be reassessed and updated where possible.

Halcrow won the international design competition in 2003 in association with DHV of the Netherlands and Norplan of Norway.

“Our job was to review the existing designs and then produce technical documentation for tenderers that allowed the work to proceed. The actual design changes were done under our direction by the Russians through their design institutes,” says Halcrow project manager David Edwards.

This was not an easy job. The project had been underway for almost a decade before it was halted. Much had been done, much had still to be done.

SLUICES

Sluices control flows of water in and out of Neva Bay

The embankment and sluices to the north of Kotlin Island were all substantially built and in place and the box girder bridge at the secondary navigation channel was fabricated but sitting on the ground rusting away. There were gaps in the viaduct leading to the bridge and the sea channel was a 17m deep hole covered in scrub and home to a pack of wild dogs.

“The gate itself was in 230 fabricated sections in a yard in Gorskaya and had been sitting there since the 1990s,” says Edwards.

“South of Kotlin the embankment was part built to a low level, about 3m above water level, with the final embankment height being 6.5m, and the two sea sluices were half complete.

“The gate itself was in 230 fabricated sections in a yard in Gorskaya and had been sitting there since the 1990s.”

David Edwards, Halcrow

“The embankment built out from Bronka on the southern mainland petered out in the water separated by almost 1km of deep water from a 25m deep cofferdam containing partially completed docking chambers for the main gates and a section of cut and cover tunnel.

“The gates were in sections in a steel yard,” he says. “Most of the tunnel was concreted bottom, sides and top but cast in 60m section with no joints completed so there were 2m gaps between the sections.

The docking chambers − which are 13m deep when complete − were concreted up to between 6m and 7m and the training wall for the navigation channel was also at half height only. It was quite hard to make sense of all the pieces.

“We had to update the designs according to revised design codes, incorporate new materials for example for tunnel and bridge joints, react with redesigns to extra wind and wave data that had become available, all without reliable as-built documentation for the existing structures, and with many of the original designers having retired. Plus, we were working with Russian codes which are not particularly compatible with the Fidic contract to which we are operating.”

Edwards says it is a testament to the ability and goodwill of all the nationalities, companies and individuals on the scheme that work restarted swiftly in 2005 and so much has been achieved in a short space of time.

The biggest challenges, not surprisingly, have been the gates to close off the navigation channels.

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