Xylem Goulds S10020 Manuel D'instructions page 13

avoid undermining foundations of existing structures
and contact with underground utilities. In the absence
of building codes or regulations, maintain a minimum
distance of five feet plus a slope of 45º from the bottom
of the compacted sub-base to the bottom of the
adjacent structures, foundations, footings and property
lines (as shown in the illustration on page 14).
Additional distances may be required to assure that
any loading carried or created by the foundations and
support cannot be transferred to the basins.
MAXIMUM BURIAL DEPTH. If burial depth is greater
than the basin height, contact Topp Industries, Inc. to
determine if additional wall reinforcement is required
and secure written authorization.
HANDLING OF EXCAVATED MATERIALS. Excavated
materials, which cannot be removed from the jobsite,
should be carefully stored as far from the edge of the
basin excavation as possible. Unless approved for use as
backfill, excavation materials should be securely stored
separate from approved backfill materials.
WORK AREA SAFETY. Safe installation procedures shall
be the sole responsibility of the basin installer. Work
safety requirements are defined in U.S. Department of
Labor 29 CFR part 1926, subpart P, Excavations.
BACKFILLING
GENERAL. Careful selection, placement and
compaction of approved backfill material are critical to a
successful basin installation. Among common problems
associated with basin leaks and premature failures are:
• Use of an 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.
PLACEMENT OF BASIN. The bottom of the basin
excavation should be covered with suitably graded,
leveled and compacted backfill material to a depth of
at least 12 inches (compacted sub-base). If a concrete
hold-down/anti-floatation pad is required, this bedding
can be reduced to a depth of at least 6 inches. The basin
should then be carefully lowered into the excavation and
centered on the compacted backfill or concrete pad
(see illustration on page 14).
WARNING! 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 structure failure and is never permitted.
BACKFILL MATERIAL. Backfill material should be
clean, well granulated, free flowing, non corrosive
and inert. It should be free of ice, snow, debris, rock,
or organic material, all of which could damage the
tank and interfere with the compaction of the backfill
material. The largest particles should not be larger than
¾ inch. Not more than 3 percent (by weight) should
pass through a #8 sieve, and the backfill material should
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 inch and a maximum
diameter of ¾ inch.
• Crushed Rock, washed and free-flowing angular
particles between 1/8 inch and ½ inch in size.
PLACEMENT AND COMPACTION OF BACKFILL.
Compaction of backfill materials should be adequate
to ensure the support of the tank and to prevent
movement or settlement. Backfill materials should be
placed in 12 inch lifts and compacted to a minimum soil
modulus of 700 pounds per square foot (psf).
SUPPORTING PIPING, EQUIPMENT AND
ACCESSORIES. Support for piping, equipment and
other accessories must be provided during backfilling.
Using the basin to support piping, equipment, cribbing,
bracing or blocking is never permitted. During
backfilling, temporary supporting materials must be
carefully installed and removed to prevent damage to
the basin, piping or equipment.
WARNING! Using the basin to support any loading
carried or created by piping, equipment, cribbing,
bracing or blocking is never permitted.
ANCHORAGE
GENERAL. When basin installations are located in
areas subject to high water tables or flooding, provision
should be made to prevent the basins, 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 tank, backfill materials and the
surrounding soil.
METHODS OF ANCHORING. All methods of anchoring
basins use the weight of the backfill materials to
offset the buoyancy forces. The use of supplemental
mechanical anchoring methods (a concrete hold-down
pad) increases the amount of backfill ballast which is
mechanically attached to the basin. The recommended
method of attachment is to pour concrete grout over the
basin's anti-floatation flange and concrete hold-down
pad (see illustration on page 14).
ANCHORAGE REQUIREMENTS. Requirements for
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 that specific installation.
WARNING! Use "submerged" material weights
when calculating anchorage requirements. 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.
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