Grenades will hold Cambridge's new ice rink up for weeks
But operator CLIC says the delay will not have a major impact on opening plans.
Plans to open the new Cambridge ice rink next autumn remain on schedule even though 40 Home Guard grenades were found during the excavation process.
The self-igniting phosphourus grenades could burst into flames when exposed to the air.
Any delay, while the Army bomb disposal team clears the site off Newmarket Road, is likely to be measured in “weeks”rather than months so will not have a major impact on the opening plans.
Cambridge Leisure and Ice Centre (CLIC), the new ice arena owner, said: “We are relieved that no-one was injured and glad that the precautions put in place worked well.
“The delay to the project completion can’t be assessed finally until the extent of any remaining ordnance is known. But it’s likely the delay will be weeks rather than months.
“Cool Venues, the developer, is working closely with contractor Melcon to recover as much time as possible.
“CLIC is very grateful to the rapid and professional response of the emergency services, especially the bomb disposal person.”
Work on the site is expected to resume next month after the clearance procedure has been undertaken.
At least 40 of the devices have been removed from the area but further investigations are required to ensure that work on the new arena can begin once more.