@CalamityJane,
Well, actually it isn't a just a ban for a burquini but for anything besides "traditional swimwear" (swimming trunks, swimming costume, bikini).
And not only since recently but since years (from 1971, current version is from 2006
pdf here)
According to the regional paper, men weren't allowed who entered the pool in underwear as well.
The "only women day" in that said indoor pool isn't observed by most local Muslim women, because a male guard still is in the building and it's possible to look inside through a glassed wall.