Septic tank, lined gravel garden with flow below the surface, subsoil irrigation. Sized by process models (P-k-C*, Darcy, loading limits, the months), beside Mark Nelson's rules. Every figure names its source.
The site
Loading the design software
Runs the Wastewater-Gardens-Toolkit's own code in this browser. A design here is a study, not a stamped design: a licensed engineer and the permitting office review any garden before it is built.