oil tank removed without written permit?

[awin w]

last week, friend and I viewed an oldtimer during its open house in Burnaby.
there was a square of patched lawn in its backyard, thus we asked the agent about oil tank removal.
he said the oil tank was removed but there is no certificate.
How is that possible in Burnaby?
New building permit must be subject to written certificate of oil tank removal, isn't it?