This area 51 styled fenced block is actually home of the Airlie road uranium filter. This bore is the backup water supply for Bendemeer during dry times.
It was comissioned in 2018 after it was found that the naturally occuring uranium levels exceeded the NSW safe drinking levels.
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The container you are hunting here is a dutch speculaas Tin, it is big enough for a few swappables and odds and bobs.
Happy hunting