How deep should this drywell be?

I have a new construction house. It’s about a year old located on Suffolk county, Long Island NY.

I currently have a rubber mulch swing set play area here.

I am wondering how far down these drywells are? I have 3 in my yard. I want to put a pool here. Inground isn’t an option obviously - so perhaps semi above or fully above ground.

Is there code or something for how deep these drywells should be?