Big Time Hater
Choose plants that like it wet, and poor drainage.I also will be removing an above ground pool and hopefully planting a garden in its spot. Issue I have is the area is very wet as it is a low spot with poor draining clay soil.
Sounds like you have plenty to do already, consider planting what will do well in the conditions you have, as opposed to fighting it.
More plants die from being waterlogged all winter, being planted in poor conditions for the plant in western Washington than anything else.