Installation Site Selection
1.
Avoid installation of the tank in vehicular traffic areas. The tank is
designed for non-traffic applications.
2.
The maximum vehicle load is a 4,500-pound (20 kN) axle load at a
soil cover depth of 6 to 48* inches (150 to 1,200 mm).
*18-inch (450 mm) max. in Florida for Cat. 3 TW and IM-1060 tanks; 48-inch
(1,200 mm) max. in Florida for Cat. 4 IM-1060; 36-inch (900 mm) max. in
Massachusetts, New Hampshire, North Carolina, and Oregon.
3.
The tank shall not be installed where the subsurface water level
outside the tank exceeds the height of the outlet pipe saddle. Follow
Table 4 guidelines.
Excavating and Preparing the Site
1.
Unless buoyancy control measures are required, the excavation
width and length should be 12 to 36 inches (300 to 900 mm) larger
than the tank on each side. See Infiltrator IM- and TW-Series Septic
Tank Buoyancy Control Guidance document, available online at www.
infiltratorsystems.com, for specific excavation requirements.
2.
Excavate to account for the height of tank. 55 inches (1,375 mm) for
the IM-1060, 51 inches (1,275 mm) for the TW-900 through TW-1500,
and 50 inches (1,250 mm) for the TW-300 and TW-500. Also account
for 4 inches (100 mm) of bedding (if required), and backfill thickness
(permissible cover depth is 0.5 to 4 feet (150 to 1,200 mm) of soil).
Note: If the water level outside the tank exceeds the height of the outlet pipe
saddle, tank structural integrity may be compromised. Follow Table 4 guidelines.
3.
Inspect bottom of excavation to verify suitability of native soil for tank
installation. Soils with large, protruding, or sharp stones or other similar
objects that may damage the tank are not suitable.
4.
The tank may be bed either in suitable native soil (see Backfilling the
Tank section) or a minimum 4-inch (100 mm) layer of pea stone, sand,
gravel, or other similar material having particles less than 3 inches (75
mm) in diameter.
5.
Create a uniform, level bedding surface to ensure that the bottom of
the tank is evenly supported at the base of the excavation. Verify that
the base of excavation is flat.
the drill points provided at each of the inlet and outlet ports according
to the Inlet and Outlet Hole Locations section of this document. The
inlet and outlet may be drilled on either the sides or ends of the tank,
as required based on applicable codes and site conditions.
Florida, Indiana, Kentucky, Oregon, West Virginia and certain Texas tank inlet/
outlet holes are factory drilled.
3.
The gaskets supplied with the tank are compatible with Schedule
40 and SDR 35 pipe using a 5-inch-diameter (125 mm) hole saw with
IM tanks, and a 5¼-inch-diameter (133 mm) hole saw with TW-Series
tanks.
4.
Install the rubber gaskets at the inlet and outlet.
5.
Using the tank’s integral lifting lugs, lower tank into excavation.
6.
Slide the inlet and outlet pipes* through the gaskets.
*For North Carolina, the inlet pipe shall be a straight pipe with no tee.
7.
Horizontally position the tee 1½ inches (40 mm) from the access
port rim as shown in the detail below. This allows the tee to fit into the
access port lid.
8.
Install lids and risers (see Installing Risers section) as necessary.
Backfilling the Tank
Note: Infiltrator tanks do not require filling with water prior to backfill placement.
Water filling is advisable if tank is left in an open excavation that may fill with water.
1.
Backfill with suitable native soil. If native soil is unsuitable, replace
unsuitable fraction with suitable soil.
2.
Suitable soil shall include soil textural classes defined in the United
States Department of Agriculture soil triangle. Suitable soil textural
classes are based on the tank installation depth, as measured from
finished grade to the top of tank.
a).
For a tank installation depth of 0.5 to 2.0 feet (150 to 600 mm),
suitable soil textures include:
Installing the Tank
1.
Inspect the tank for damage before installation.
2.
If the tank inlet and outlet penetrations are not drilled, drill holes using
vii.
The following, assuming that the sand particle fraction by weight
(i.e. % that would be retained on No. 200 sieve, as per ASTM D2487)
is greater than 30%: silt loam, clay loam, and clay
viii.
The following, assuming that the sand particle fraction by weight
(i.e. % that would be retained on No. 200 sieve, as per ASTM D2487)
is less than 30% and the soil is shown to be dilatant (refer to Step 5
below for simple dilatancy test to be conducted in the field): silt loam,
silt, clay loam, silt clay loam, silty clay, and clay
b).
For a tank installation depth that is greater than 2.0 feet and up to 4.0
feet (600 to 1,200 mm), suitable soil textures include:
vii.
Silt loam, clay loam, and clay having at least a 30% sand particle
fraction by weight (i.e. % that would be retained on No. 200 sieve, as
per ASTM D2487).
i.
Sand
ii.
Loamy sand
iii.
Sandy loam
iv.
Loam
v.
Sandy clay loam
vi.
Sandy clay
i.
Sand
ii.
Loamy sand
iii.
Sandy loam
iv.
Loam
v.
Sandy clay loam
vi.
Sandy clay
GASKET
INLET/ OUTLET
TEE (TYPICAL)
TANK
INTERIOR
TANK WALL
(IM-1060 SHOWN)
ACCESS
OPENING
LID
ACCESS PORT RIM
POSITION TEE 1.5 in (40 mm)
FROM PORT RIM
MOUND BACKFILL FOR
POSITIVE DRAINAGE
3 in (75 mm)
MAXIMUM
PARTICLE SIZE
PLACE SOIL IN
12 in (300 mm)
LIFTS AND
COMPACT
PLACE SOIL
BETWEEN RIBS
SUITABLE NATIVE
SOIL BACKFILL
SUITABLE SOIL COVER
12 - 36 in (300 - 900 mm)
6 in (150 mm) MIN. SOIL COVER
IM-1060 TANK END VIEW SHOWN FOR REFERENCE
TANK BURIAL DEPTH
6 in (150 mm) MINIMUM
48 in (1,200 mm) MAXIMUM
TW-300 and TW-500: 50 in (1,250 mm)
IM-1060: 55 in (1,375 mm)
TW-900 through TW-1500: 51 in (1,275 mm)
PLUS DESIGN BACKFILL DEPTH
SUITABLE NATIVE SOIL OR
GRANULAR MATERIAL
TW-300 and TW-500: 50 in (1,250 mm) IM-1060: 55 in (1,375 mm)
TW-900 through TW-1500: 51 in (1,275 mm)
IM-1060 TANK
SECTION VIEW
SHOWN FOR
REFERENCE
CREATE
BERM AT
HOLE EDGE
TO DIVERT
SURFACE
RUNOFF
septic tanks
o
Infiltrator IM or TW tank
o
Access port lids (included)
o
10 screws per lid (included)
o
Inlet/outlet gaskets (included)
o
Inlet/outlet tees*
o
Tape measure
o
Pipe, risers, etc.
o
Socket wrench
o
Excavator
o
Shovel
o
Level
o
5-inch-diameter (125 mm) hole
saw (IM tanks)
o
5¼-inch-diameter (133 mm)
hole saw (TW-Series only)
o
Utility knife
o
PVC pipe glue with primer
*tee inclusion varies by state/province
Materials and Equipment Needed
Infiltrator IM
™
- and TW
™
- Series
Septic Tank General Installation Instructions
IM-1060 TANK
SECTION VIEW
SHOWN FOR
REFERENCE
TW-300 AND TW-500: 50 in (1,250 mm)
IM-1060: 55 in (1,375 mm)
TW-900 THROUGH TW-1500: 51 in (1,275 mm)
POSITION TEE 1.5 in (40 mm)
FROM PORT RIM
ACCESS
OPENING
LID
ACCESS PORT RIM
INLET/OUTLET
TEE (TYPICAL)
GASKET
TANK
INTERIOR
TANK WALL
(IM-1060 SHOWN)
Note: Illinois
requires a 6-inch-
diameter (150 mm)
drop for inlet tee.
Before You Begin
Infiltrator Systems’ septic tanks must be installed according to
state and/or local regulations, which supersede the manufacturer’s
installation instructions. If unsure of the installation requirements for
a specific site, contact the health department or permitting authority.
WARNING: IMPLOSIONS MAY CAUSE SERIOUS INJURY
Follow Infiltrator Systems Inc. vacuum test instructions
OCTOBER 2011
