Floods strike the city twice a year on average. A 25.4-kilometer embankment across Neva Bay, featuring some of the worlds largest horizontal sector gates, was designed in the 1970s, started in the 1980s but halted in 1987 for environmental and financial reasons as the Communist regime started to crumble.
Some 30 foreign engineers plus more locals are now beginning to review construction done so far and designs for remaining work. Site work could begin next year, and major elements will start in 2005, says David Birch, a water sector director at U.K.-based Halcrow Group, leader of the engineering team. Most of the design remains good, but dated specifications for elecrical and mechanical equipment need to be updated, he adds.
Supported by the local design institute LenHydroprojekt plus Dutch and Norwegian firms, Halcrow will also help the owner prepare a construction bidding strategy, and draft technical documents. The engineers will ensure design com-pliance during construction. But the Committee of the Russian Federation for Construction and Housing Complex (Gosstroy), the project agency, is now seeking a project manager.
When complete, the barrier will include a 25.4-kilometer embankment with six gated discharge sluices and two navigation channels. The bigger, 200-meter-wide channel, designated S2, will be sealed during floods by two 130-m-long curved gates. These "fantastic structures" will normally rest in curved drydocks on either side of the channel. When needed, the docks will be flooded and gates will float to closure, turning by steelwork arms pivoted at their ends. Click here to view map & diagram
A more conventional vertically lifting gate will seal opening S1, which is about half as wide as S2. It will take about 20 minutes to close the gates and sluices will need 30 Mw of electrical power, says Birch. Additionally, the current project must build a tunnel under the main channel and bridge over the smaller one for a six-lane highway planned for a later date.
The European Bank for Reconstruction and Development, London, is providing $225 million in project loans. Previous concerns about the jobs environmental impact have been allayed by St. Petersburgs wastewater treatment improvement program, says EBRD.team of international engineers has resurrected a large but unfinished flood control project from the Soviet era. Plans are under way to complete the last 35% of Russias vast flood barrier at St. Petersburg within five years at an estimated cost of $400 million.