If you can make a roll or ball it's not loam. Sounds like clay to me, whether it's lean to fat I don't think it matters but when talking about bentonite and lbs per acre, that's mixed into existing substrate and compacted. Final layer should be high plasticity clay if available.
Plan 3ft deeper than what you want for finished depth is soil allows.
We did some hatchery runs NW of you in some lean sandy clay but we used a completely different method on those. Clay would not work because of frequent draw-down and re-fill.
