© Presby Environmental, Inc., Maine Design & Installation Manual, June 2019 Edition -23-
34.8 Install System Sand and/or Sand Fill Immediately After Excavation
a)
To protect the tilled area (System Sand Bed Area and System Sand Extension Area) from damage by
precipitation, System Sand should be installed immediately after tilling.
b)
Work off either end or the uphill side of the system to avoid compacting soil.
c)
Keep at least 6 in. of sand between the vehicle tracks and the tilled soil of the site if equipment must
work on receiving soil.
d)
Track construction equipment should not travel over the installed system area until at least 12 in. of cover
material is placed over the pipes.
e)
Heavy equipment with tires must never enter the receiving area due to likely wheel compaction of
underlying soil structures.
34.9 Distribution Box Installation
To prevent movement, be sure D-boxes are placed level on compacted soil, sand, pea gravel base, or concrete pad.
34.10 Level Row Tolerances
Use a laser level or transit to install rows level. Variations beyond 1 in. (±1/2") may affect system performance and
are not acceptable.
34.11 Correct Alignment of Advanced Enviro-Septic Bio-Accelerator Fabric
The Bio-Accelerator (white geo-textile fabric) is to be positioned centered along the bottom of the pipe rows (sewn
seam up).
34.12 Row Spacers
System Sand may be used to keep pipe in place
while covering, but simple tools may also be
constructed for this purpose. Two examples
are shown. One is made from rebar, the other
from wood. Center-to-center row spacing may
be larger than specified by this manual.
Caution: Remove all tools used as row spacers
before final covering.
34.13 Connect Rows Using Raised Connections
Raised connections consist of offset adapters, 4 in. PVC sewer and drainpipe, and 90° elbows. They enable greater
liquid storage capacity and increase the bacterial surfaces being developed. Use raised connections to connect the
rows of the field (see para. 3.5, pg. 4 ). Glue or mechanically fasten all pipe connections.
34.14 Backfilling Rows
a) Spread System Sand between the rows.
b) If using AES, confirm pipe rows are positioned with Bio-Accelerator along the bottom (sewn seam up).
c) Straddle each row of pipe and walk heel-to-toe its entire length, ensuring that System Sand fills all void
spaces beneath the pipe.
d) Finish spreading System Sand to the top of the rows and leave them exposed for inspection purposes.
34.15 Backfilling and Final Grading
Spread System Sand to a minimum of 3 in. over the pipe and a minimum of 6 in. on all four sides beyond the pipes.
Spread soil material free of organics, stones over 4 in. and building debris, having a texture similar to the soil at the
site, without causing compaction. Construction equipment should not travel over the installed system area until at
least 12 in. of cover material is placed over the pipes (H-10 Loading). 18 in. of cover material over the field is
required for H-20 loading (see para. 29.0, pg. 17).
34.16 Fill Extensions Requirements
All fields with any portion of the System Sand bed above original grade require 3 ft. fill extensions on each side
beyond the outside edge of all AES or ES pipes (5 ft. on downhill side of systems sloping greater than 10%) and then
tapering to meet existing grade at a maximum slope of 4:1 (see illustration in para. 39.0, pg. 29).
34.17 System Soil Cover Material
A minimum of 4 in. of suitable earth cover (topsoil or loam), with a texture similar to the soil at the site and capable of
sustaining plant growth, must be placed above the installed system.
34.18 Erosion Control
To prevent erosion, soil cover above the system shall be planted with native, shallow-rooted vegetation such as
grass, wildflowers and certain perennials or ground covers.
WELDED REBAR
HANDLE
BERM SAND AT BASE OF
PIPES TO HOLD IN PLACE
WOODEN FRAME
