Step 2 – Determine Buoyancy Control Method
Step 2 is used if the Step 1 analysis shows that buoyancy control is required for the tank model and installation conditions. The site-specific maximum
height of water outside of the tank and above the tank bottom and the depth of soil cover above the tank top must be known to complete Step 2.
Table 2 Instructions
For the appropriate tank model, select the desired buoyancy control method under each method description column. Refer to the Compatible Devices and
Products and Step 3 – Implementation sections of this document for additional information on the buoyancy control methods shown in Table 2.
Supplemental Force
The minimum supplemental downward force required is included in Table 2 to allow custom buoyancy control methods. These values include a factor
of safety of 1.5 applied to the calculated force required to restrain the tank. Custom-designed buoyancy control methods shall conservatively consider
saturated conditions from the bottom-of-tank elevation to ground surface. As long as buoyancy control is provided that supplies the minimum weight listed
in the table (for poured-concrete blocks or other methods designed by third parties), the tanks are calculated to be stable for the water height outside
the tank and above the tank bottom and corresponding soil cover conditions. All Infiltrator strapping and fastening recommendations apply for custom-
designed buoyancy control methods. Contact Infiltrator’s Technical Services Department with any questions regarding supplemental force requirements.
Table 2: Buoyancy Control Method Selection
Tank
Model
Parameter I:
Water height above tank bottom
Parameter II:
Soil cover depth above
tank top
Minimum
supplemental
downward
force required
1
(total, both tank
sides)
Buoyancy Control Methods
Concrete-filled
half pipe
(min. length/
side)
Concrete
parking
bumpers
(min. length/
side)
Concrete
traffic
barriers
(min. length/
side)
Helical
anchors
(min.
no./side)
Concrete collar
(min. width x min.
height)
IM-540
36 in (900 mm) to outlet pipe saddle
2
6 in (150 mm) to 12 in (300 mm) 2,200 lbs (1,000 kg)
3.8 ft (1.2 m)
3.8 ft (1.2 m)
3.8 ft (1.2 m)
2
6 in (150 mm)
x 9 in (225 mm)
IM-1060 36 in (900 mm) to outlet pipe saddle
2
6 in (150 mm) to 12 in (300 mm) 2,700 lbs (1,225 kg)
4.2 ft (1.3 m)
4.5 ft (1.4 m)
4.2 ft (1.3 m)
2
12 in (300 mm)
x 9 in (225 mm)
IM-1530 30 in (750 mm) to outlet pipe saddle
2
6 in (150 mm) to 12 in (300 mm) 4,300 lbs (1,955 kg)
6.3 ft (2.0 m)
6.5 ft (2.0 m)
6.3 ft (2.0 m)
2
12 in (300 mm)
x 9 in (225 mm)
NOTES:
1. See Supplemental Force discussion below.
2. IM-Series outlet pipe saddle height is 43 inches (1,075 mm) above tank bottom (see Figure 1).
Contact Infiltrator Water Technologies’ Technical Services Department for assistance at 1-800-221-4436.
