LONDON'S OLYMPIC bosses revealed this week that the 2012 Olympic Park site will not be free from overhead power lines until 2009, one year later than originally planned.
Pylons will be temporarily relocated and work on the park construction rescheduled to remove burial of the power lines from the critical path.
Two pylons are now scheduled to be moved by the end of 2007.
Olympic Delivery Authority chief executive David Higgins told NCE that aiming to switch power transmission from above to below ground in 2008 was too risky, with electricity companies providing only two months in which to complete the work.
'If we get it early great, ' said Higgins, 'but you can only do it in such a small window of time that we planned for it to be in 2009.
'Temporarily relocating some of the national grid pylons allows us to get access to more of the village site and takes the tunnelling off the critical path, ' said Higgins.
Fifty-two electricity pylons are to be removed from a 6km route that spans the Lower Lea Valley and runs through the heart of London's Olympic Park.
Power supplies will be switched to run through two 20m deep tunnels of 2.5m and 4m internal diameter. Contractor Murphy is due to start the tunnel bore next month.
When Sebastian Coe and his team presented London's bid to host the 2012 Games in Singapore last year, the tunnelling and switchover of power supplies was due to be completed by summer 2008 (NCE 14 July 2005).
Switchover can only take place in July or August when demand for electricity is low.
If that deadline is missed there could potentially be a year's delay to work above ground.
Construction of the Athlete's Village is due to start next year, with work on the main Olympic Park kicking off in summer 2008.