i would recomend to never bleach wood. boiliing and salt baths are much better alternatives. boiling it would also help it sink. how big is it?
i doubt that any heavy metals that would be present on/in the wood that wouldn't get washed off by a power washer would get removed by a dechlorinator without lots of the dechlor and a long soak in it.
i doubt that any heavy metals that would be present on/in the wood that wouldn't get washed off by a power washer would get removed by a dechlorinator without lots of the dechlor and a long soak in it.