Presby Environmental systems have most all changed to the “Advanced Presby Enviro” pipe because it can be installed at 24” above the seasonal high water table, or 30” above ledge.  This is lowest distance of any passive system available. Therefore, Hogg Hill Design and other NH designers use this product in a great number of in-ground designs.  We will discuss the pro and cons of different dispersal system types based upon your soils before design begins. 

Sloping 4 pipe Presby dispersal area with bird bath vent

Plan view - Gravity fed mound system