Welcome... Can't assist you much from Singapore... But I am sure the guys in FL (there should be some in this forum) can help you out...
Where I am from, there is heaps of trash buried in the sand. Locals here are just too bored at times and will bury their empty beer cans, toss the bottle caps, ring tabs, empty wrappers into the sand. On occasion, I'm able to pick up current coins and I also found a few Thai and Indian coins too.
HH