7353000J
Copyright © Liberty Pumps, Inc. 2021 All rights reserved.
5 | EN
Work Area Safety
Safe installation procedures are the sole responsibility of the basin
installer. Work safety requirements are defined in US Department
of Labor 29 CFR 1926, Subpart P: Excavations.
Backfill
Careful selection, placement, and compaction of approved backfill
material is critical to a successful basin installation. Among the
common problems associated with basin leaks and premature
failures are:
•
Use of incorrect backfill material
•
Inadequate or improper placement or compaction
•
Rocks, clods, or debris left in the excavation or basin
•
Voids under or around the perimeter of the basin
•
Failure to prevent the migration of backfill materials
Basin Placement
Placement of a basin on a concrete pad or compacted
sub-base smaller than the total basin bottom area or on
intermediate supports (saddles) will cause uneven distribution
of loads. This may contribute to structural failure and is never
permitted.
Cover the bottom of the basin excavation with suitably graded,
leveled, and compacted backfill material to a depth of at least 12”
(compacted sub-base). If a concrete hold-down/anti-flotation pad
is required, this bedding can be reduced to a depth of at least 6”.
Carefully lower the basin into the excavated area and center on
the compacted backfill or concrete pad.
Backfill Material
Ensure backfill material is clean, well granulated, free-flowing,
non-corrosive, and inert; free of ice, snow, debris, rock, or organic
material, all of which could damage the basin and interfere with
the compaction of the backfill material. The largest particles shall
not be larger than 3/4”. Not more than 3% (by weight) should
pass through a #8 sieve, and the backfill material must conform to
ASTM C-33, Paragraph 9.1 requirements. Approved backfill
materials include:
•
Pea gravel, naturally rounded particles, with a minimum
diameter of 1/8” and a maximum diameter of 3/4”
•
Crushed rock, washed and free-flowing angular particles
between 1/8” and 1/2” in size
Backfill Placement and Compaction
Do not exert heavy pressure or run heavy equipment on the
backfill material as this could cause the tank to collapse.
Compaction of backfill materials must be adequate to ensure the
support of the basin and to prevent movement or settlement.
Place backfill materials in 12” lifts and compacted to a minimum
soil modulus of 700
pounds per square foot.
Support Piping, Equipment and Accessories
Using the basin to support any loading carried or created by
piping, equipment, cribbing, bracing, or blocking is never
permitted.
Provide support for piping, equipment, and other accessories
during backfilling. During backfilling, temporary support must be
carefully installed and removed to prevent damage to the basin,
piping, and/or equipment.
Anchorage
When basin installations are located in areas subject to high water
tables or flooding, make provisions to prevent the basin, either
empty or filled, from floating. The buoyancy force to be offset is
determined primarily by the volume of the basin. The principle
offsetting factors include:
•
Backfill materials
•
Concrete hold-down pad
•
Friction between the basin, backfill materials, and
surrounding soil
Anchorage Methods
All methods of anchoring the basin use the weight of the backfill
materials to offset the buoyancy forces. The use of supplemental
mechanical anchoring methods (i.e., a concrete hold-down pad)
increases the amount of backfill ballast that is mechanically
attached to the basin. The recommended method of attachment is
to pour concrete grout over the basin’s anti-flotation flange and
concrete hold-down pad.
Anchorage Requirements
Use “submerged” material weights when calculating
anchorage requirements.
Requirements of anchorage, thickness of concrete hold-down
pads, as well as the size of anchors and reinforcement must be
calculated for each installation based on the environmental
conditions of the specific installation.
Example:
weight of concrete (150
pounds per cubic foot) minus
the weight of the water (62.4
pounds per cubic foot) equals a
“submerged” weight of 87.6
pounds per cubic foot.
RISK OF SERIOUS INJURY OR DEATH
RISK OF SERIOUS INJURY OR DEATH
RISK OF SERIOUS INJURY OR DEATH
