WORKMEN at the Uxbridge Lido site were stunned when they unearthed a box of World War Two bombs last week.
The startling discovery was made at 9.49 on Friday morning at the site in Gatting Way.
A controlled explosion was carried out by a specialist police unit at about 2pm.
Cordons were put up on Gatting Way and Park Road as all three emergency services attended the scene.
When builders dug up the box of explosives, a strong smell of chemicals overpowered the area, and it was this that led to the emergency services being first alerted.
Police Explosives Officers attended the scene and soon had the situation under control, so that army bomb disposal experts did not have to be called in.
Nobody actually lives in the roads, but staff at The Young Ones Nursery, on Gatting Way, had to be evacuated, and members of the public were stopped from entering the site.
The council's environmental health officer also attended the scene.
A police spokesperson said: "Our specialist officers executed a controlled explosion at about 2pm which resulted in a lot of smoke, while other officers made the area safe."
Laraine Smith, Principal of Uxbridge College, based in Park Road, said: "Following advice from police on Friday morning, the Gatting Way exit from Uxbridge College was closed temporarily, and everyone on campus was advised of this and requested to use the front entrance instead.
"As a neighbour, we were impressed and very pleased by how well the situation was handled to ensure everyone was kept safe.
"We did not know at the time that World War Two explosives were involved - the college may have 42 years of history to its name, but that is no competition for something like this!"