Mantis & Other Leaching Units
"Proprietary" leaching systems involve leaching structures that are patented in design. They include plastic leaching chambers, "corrugated" leaching systems, "form cell Living Filter" units, and pressure-dosed dispersal systems. Each are available in a variety of widths and heights, though they're generally shallow in profile. They must be installed according to the specific instructions of the manufacturer, and are usually backfilled with select fill or sand.
Plastic leaching chambers, such as made by Infiltrator or Cultec, are interlocking mini-gallie-like structures. The tops are rounded to gain strength from that venerable form, the arch. The perforations on the sides have various fins facing outward to increase surface area. The taller units can be used side-by-side in level trenches up to six feet wide as an alternative to galleries. The shorter units can be used as an alternative to leaching trenches in an excavation up to four feet wide.
Elgin Corporation's "Mantis 536-8" system has gained popularity in recent years, in part because the State of Ct. has granted it a high 11.0 Square feet per Linear foot calculation for the 18" high units and 6.5 for the 12" high units. These units consist of multiple vertical plastic panels about 4" wide that are covered with filter fabric. The panels are connected by a 4" perforated pvc pipe, near the top, that runs through all the panels. The spaces between the panels, as well as the rest of the 4' wide excavation, are filled with compacted sand that meets ASTM C 33 specifications, basically concrete sand.
There are also 6' wide units available, requiring a 7' wide excavation.
With the Mantis system it is a good idea to size the leaching system 33% larger than required, if possible.
Their installation manual: http://eljen.com/Downloads/Mantis/DesignManuals
Below is a Mantis 536-8: 3' wide, 5' long, and 18" high.