Installation Manual:
AdvanTex
®
AX20-RT Treatment Units
NIM-ATX-AXRT-1
Rev. 1.0, 1/10
© 2010 Orenco Systems
®
Inc.
15
Step 12: Complete Final Backfilling
IMPORTANT:
When
backfilling, be careful not to alter the
slope of pipes. Brace the pipes or place the pipes on a compacted
bed and carefully fill around them.
NOTE:
Before backfilling, make sure the AX20-RT unit lid and
all riser lids are bolted down.
Step 12a:
Backfill the septic tank excavation if it has not yet
been done. Follow the tank manufacturer’s guidelines for back-
filling.
Step12b:
Backfill
and compact around the AX20-RT unit in
maximum 12-in. (305-mm) lifts. Native material is acceptable if
there are no large or sharp rocks that may damage the unit walls.
If native material is not usable, backfill with sand or pea gravel.
For installations in non-cohesive soils* with high seasonal
water tables, use ¼-in. crushed rock as the backfill material.
The top of the AX20-RT lid should sit 2 in. (50 mm) above
final grade.
IMPORTANT:
After backfilling, call the system’s Service
Provider to arrange for the official System Start-up.
*
As described in OSHA Standards (29 CFR, Part 1926, Subpart P, Appendix A), noncohesive
soils or granular soils include gravel, sand, or silt with little or no clay content. Granular
soil cannot be molded when moist and crumbles easily when dry. Cohesive soils include
clayey silt, sandy clay, silty clay, clay, and organic clay. Cohesive soil does not crumble,
can be excavated with vertical sideslopes, is hard to break up when dry, and when moist,
can be rolled into threads without crumbling. For example, if at least a 2-in. (51-mm) length
of 1/8-in. (3-mm) thread can be held on one end without tearing, the soil is cohesive.
12b
Backfill the AX20-RT in 12-in. (300 mm) lifts
Maintain minimum
1
/
8
in.
(10 mm or 1%) slope
2 in. (50 mm)
above final grade
