Might the amount of residual fuel that the foam absoprbed when it was used to fill the tank be a determining factor on whether the materail is non-haz or haz waste?
How much formaldehyde is present?
Can the foam be cut out of the tank safely - this link suggests some problems with vapours and non-foaming liquid residues.
http://ezinearticles.com/?Managing-the-Risks-of-RG22-Foam&id=4607466
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