I appreciate it. Thanks. I’ve been looking for a suitable alternative, and should’ve said so in the posting.
I’ve tracked it to a company in Australia and New Zealand called Geotas. This same product has been produced under the name Advanedge, and Megaflo. Though I have heard some sites referring to it as ‘sewer pipe,’ I found it listed as Subsoil Drainage Pipe.
Finally found a US distributor
It was listed at a 14" and 12" width. It’s a flat hdpe pipe and unfortunately I can only find it in 100’ increments for sale, at the staggering price of about $900