Local community groups and residents have stressed that visually unobtrusive spillways along the 13 outdated reservoirs on London’s Hampstead Heath would be vital to proposed flood alleviation plans.
Formal consultation began Monday
Following three months of discussions with users of the heath, its steward City of London Corporation began a formal consultation on the upgrade plan on Monday.
It has proposed a series of new upgrades. Earlier this year NCE revealed that the heath is vulnerable to a major flooding event because its water storage structures are outdated and liable to overtopping (NCE 20 January).
Local residents accept that work is needed, but representatives at this week’s meeting of the Hampstead Heath Consultative Committee said that preserving the heath is vital.
“We broadly accept the upgrades are necessary but with certain caveats,” said Marylebone Bird Watching Society member Alix Mullineaux.
“The 1871 Act [which preserves the Heath in its current state] should be made more integral to the plans.”
At the meeting residents sought assurances that they would be continually consulted about its plans during the detailed design of the upgrades.
“We broadly accept the upgrades are necessary but with certain caveats”
Alix Mullineaux, Marylebone Bird Watching Society
The most contentious point for locals is the proposal to build large and imposing structures on the Heath.
The City of London Corporation’s consultant Aecom has outlined a £15M proposal that treats the reservoirs as a single chain rather than individual entities.
Under the current Reservoirs Act 1975, only three ponds − the Highgate Men’s Bathing and Model Boating ponds on the east chain and Hampstead No 1 on the west − are statutorily required to be upgraded.
However, the new Flood & Water Management Act 2010 regulations, which are due to come into force in 2012, means that all 13 reservoirs must be upgraded.
This means that engineers can spread the impact along the ponds working with residents to find optimum solutions. Under statutory designs, which are a cheaper option, the new spillways for the three largest ponds would be much bigger.
Hard and soft engineering
“We can mix hard and soft engineering,” said dam expert and ICE panel engineer responsible for the scheme Andy Hughes.
Engineers have flexibility over the size of spillway and could incorporate embankments strengthened with geotextiles, which are more sympathetic to the surroundings than using a traditional concrete structure.
Key dates for Hampstead Heath pond upgrade
|Consultant appointed||March 2012|
|Contractor appointed||August 2012|
Detailed design including:
|March 2012 - March 2013|
|Detailed design and final budget report approval||April 2013|
|Planning approval||May - September 2013|
|Construction on site||December 2013 - March 2015|