Hi Abb, This. The original blueprint design had the collector drains located at the top of the sidewall footer. If constructed this way, the underslab drains would have had to connect to this topside footer drain through an "upwards" coupling. This is where there would be a problem with a "self-cleaning" full gravity flow design.
You got it right in your drawings on the actual construction architecture (with a tweak of angling the underdrains to be "herringbone" patterned). :-)
Flawed Drain design of original blueprints: Built differently from blueprints in actual construction. (Abb was correct).
