System Configurations - Infiltrator Presby Advanced Enviro-Septic Design And Installation Manual

2.0 SYSTEM DESIGN

2.5 System Configurations

Elevated Bed Systems
Elevated beds are designed for sites with soil, depth to groundwater or restrictive feature constraints that do not
allow for in-ground bed systems. An elevated bed system is a soil absorption field with any part of the AES system
(6 in basal system sand layer and 12 in tall AES pipe rows) is located above original grade. Side-slope tapering is
used to blend the raised portion of the system with the existing grade. Elevated bed systems require 6 in fill
extensions on each side (measured from the pipe), after which side-slope tapering is to be a maximum of 3
horizontal feet for each 1 ft of vertical drop until it meets existing grade. In systems sloping greater than 5%, there
must be a minimum of 2.5 ft of system sand extension (3 ft measured from the pipe) beyond the last down-slope
row of pipe. There must be a minimum of 12 in of cover material over the ends of all system sand extensions (if
present).
Illustration of an elevated level bed: Illustration of an elevated sloping bed:
In-Ground Bed Systems
Systems are installed at or below existing grade for sites with no soil restrictive features within 30 in of grade. In-
ground systems that slope over 5% require a 2.5 ft system sand extension on the downhill side of the field. In-
ground on level site:
Trench Systems
AES pipe may be installed in trench configurations on level or sloping terrain. Trench systems incorporate one or
more rows of AES pipe per trench. A minimum of 3 in of system sand is required above and 6 in below, between,
and around the perimeter of the AES pipe. Consult the Rules for acceptable trench width and/or required trench
separation.
© Presby Environmental, Inc., Design & Installation Manual, September 2020 Edition 11