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if both pea gravel and sand are used as backfill in the same
excavation what material should be used to prevent migration
of sand fines into voids in the pea gravel - ANSWER-Filter
Fabric
if a bottom hold down pad is used as a means of anchoring the
tank what is the
minimum distance the pad should extend beyond the sides
and ends of the
tank? - ANSWER-18 inches Beyond each side and 12 inches
Beyond each end
when installing a bottom hold down pad what should be the
proximity of the tank
to the hold down pad? - ANSWER-an adequate bedding of
backfill material
must separate the tank and
the pad.
for purposes of making tank Anchorage calculations what is
the approximate
,weight of 1 cubic foot of sand or pea gravel? -
ANSWER-60 pounds
what is an acceptable minimum burial depth of cover for steel
underground tanks in traffic areas as specified in NFPA 30? -
ANSWER-3 feet of Earth
what is an acceptable minimum burial depth of cover required
for non-metallic
underground tanks in traffic areas as specified in NFPA 30? -
ANSWER-3 feet
of
Earth
what are dead men anchors? - ANSWER-beams of reinforced
concrete placed
in the excavation with cables and or
straps attached
in dry areas where tank floatation is not a problem and which
are not subject to
traffic what is the minimum depth of cover recommended? -
ANSWER-1 foot of
backfill material plus four inches of
reinforced concrete
,and/or
1 foot of backfill covered by Filter Fabric and 1 foot of Earth
mid anchoring is a method of? - ANSWER-of preventing tank
flotation by pouring reinforced concrete over the top 1/3 of the
tank with a membrane of non conductive material separating
the concrete from the tank
for steel and FRP and FRP clad tanks the bottom of the
excavation should be covered with a bedding of backfill
material to a depth of at least? - ANSWER-1 foot
if they hold down pad is used in the bottom of the excavation the
betting may be
reduced to a depth of? - ANSWER-
6 inches
native soil may be used as a backfill for tanks when? - ANSWER-
never. Naitive
soil is unacceptable as a backfill
material
, the preferred backfill material for fiberglass reinforced plastic
tanks is what? - ANSWER-pea gravel with a minimum diameter
of 1/8 inch and a maximum diameter of 3/4 inch
the recommended backfill material for steel or fiberglass clad
steel tanks may
be all but one of the following materials which is NOT
accepted as backfill
sand?
compacted
clay?
pea
gravel?
crushed rock? - ANSWER-compacted clay is not
acceptable as backfill
use of sand slurry as a controlled mixture of sand and water
may be permitted for backfilling a tank excavation provided
what? - ANSWER-the operation is performed only by personnel
trained by the tank manufacturer and with the tank
manufacturers prior approval.