This is proprietary effluent dispersal piping approved for installation in VT as Innovative/Alternative equipment. It features  additional treatment of effluent in the distribution pipe.  See Presby's website at www.presbyeco.com for complete details from the manufacturer.  The footprint of the area required for a Presby system is usually smaller than for a traditional pipe and stone dispersal area. 

Sloping 4 pipe Presby dispersal area - bird bath vent

Plan view - Gravity fed mound system