It depends on how fine the clay is you might want to add a thicker aggregate or loom to make it easier to doze. Should get a mix of 40% clay and at least a partial till on pond bottom, with min.12" top coat packed in two layers. The sides of the pond should have clay mixture tilled in and then packed and if you have extra run clay up sides..Make sure top has drainage away from pond to prevent errosion while pond is filling. If not tarp sides with plastic untill pond fills.
Depending on how big your pond is you will need a dozer and an Track hoe to do the job right the first time a Tractor will not compact properly.
When filling the pond diffuse water coming in to prevent errossion. I would suggest you tackle this in drier times I think your getting same rains we are.
Good luck


Scott Trava
Catskill Pond
http://catskillpond.com
scott@catskillpond.com
Returning Catskill Waters To A Simpler Time
EST. 1923