The Council is reminding the public of the risks of dumping potentially explosive material.
It follows the recent discovery of several rounds of old ammunition at the Garson household recycling centre and number of old flares at the Chinglebraes waste transfer station.
The finds resulted in the recycling centre being closed for use by the public for several hours while the safe removal of the ammunition was arranged.
Follow-up precautionary checks were then carried out at all Council operated waste and recycling facilities.
The Council's Head of Infrastructure and Strategic Projects, Darren Richardson, said: "The usual process when we find items with an explosive charge at any of our waste facilities is to contact the Police for advice.
“In the case at Chinglebraes, the age and fragile condition of the flares were such that an expert team was called to carry out disposal.
“An area at Chingliebraes was cordoned off until the team arrived. The flares were then removed for safe disposal.
“We’re taking this opportunity to remind people that disposing of potentially explosive material in this way is illegal and represents a significant risk to members of the public and our staff, not to mention disruption while their safe disposal is carried out.
“It is also important to point out that that waste is incinerated in Shetland, so this presents a further layer of risk.”
Anyone with potentially explosive material for disposal should contact Police Scotland on the national enquiry line 101 to seek advice on the appropriate action to take.