Originally Posted by Scuba_Dave
You use a post hole digger to dig thru the clay
Once you hit material that will drain then you fill the hole w/gravel to allow draining
But if you have 12' deep of clay I think you would need a back hoe
Sorry for not quite understanding but your saying dig a hole? Or dig the whole patio area? Keep digging untill the clay runs out then fill with gravel for draining. But do this the whole 450sq ft patio? My one section of my yard is very wet. Last time we saw rain was sat (heavy rain) and my one section is still puddly soaked.