Mustard gasbill could topÂ£100,000
A specialist team from the Ministry of Defence finally completed the clean up in Roughton Moor Woods last week.
It brought an end to a dramatic saga which started last October with the discovery of the canisters by individuals who were reportedly searching for vintage bottles.
Two people suffered minor burns and were treated in hospital.
Three people, arrested on suspicion of possessing a noxious substance, remain under investigation.
The woods - a popular site for walkers - were immediately closed after it was discovered some of the mustard gas had leaked into the soil.
M0D staff from Porton Down were brought in and were involved in the final clean up.
It is understood the canisters were ‘dumped’ by soldiers based in the area, either during or just after the Second World War.
The MoD will cover the cost of the operation.
Cordons around the woods have been removed.