Buried Tank Installation
Tanks must be fully supported on the base by either an appropriate concrete pad
that allows no overhang or a compacted stone free sand bed.
When buried, tanks must be filled with water prior to backfilling. Tank tops
are non-load bearing and should have a trap door or access cover over them supported
by a foundation or by the ground. They cannot be supported by the top of the tank.
The backfill material shall be free of stones and foreign matter and shall be
capable of passing a No. 10 screen. The depth of this backfill should be 6" to 8"
thick around the tank and then normal backfill material may be used. Mechanical tamping
is not recommended. For tanks with extensions, the above procedure should be followed up
to or slightly above water level and from that point on up to ground level it is recommended
that a 4" thick concrete sleeve be poured around the tank in multiple lifts. If this is not
feasible then the normal backfill procedure may be used, up to 36" height above water
level, bearing in mind that backfilling will produce inward pressures on the empty portion
of the tank. Care must be exercised during this operation to prevent inward buckling.
A concrete vault must be used or a 4" thick concrete sleeve poured around the tank in
multiple lifts in areas with high water tables or poor soil conditions. If the tank is to
be used as a pump-out holding tank or similar type of operation or the tank will be left
empty or partially full, then a vault is required.
Orion Fittings recommends that tanks that are going to be direct buried, should be fiberglass wrapped.
Limestone chips are being used in numerous applications to help neutralize chemical
bearing wastes (e.g. acid wastes). After years of successful neutralization, many states
and local environmental plumbing codes call for the addition of limestone chips into acid
neutralization basins, tanks, or sumps. Water is added to the tanks to initiate the dilution
process. Orion recommends the limestone chips be one to three inches in diameter size range and have
a calcium carbonate content in excess of 90%. See chart on prior page for approximate limestone needed.
Orion's neutralization tanks must not be pressure tested. Test tank by filling with water
prior to use and inspect for any leaks.
Maintenance of Tanks
The limestone supplied by Orion are 1-3" in diameter and have a calcium carbonate
content certified to be in excess of 90%. Waste is added to the tank to help facilitate
dilution. A maintenance schedule should be established to observe and maintain proper
limestone levels in the tank. Limestone replacement should be performed at regular intervals.
Typically, once every one to three months is sufficient, however, these intervals can be increased
of decreased based upon application needs and performance. Factors affecting limestone replacement
are waste flow rated and chemical composition as well as operating temperatures. Solids in the waste
stream can plug the tank and should be avoided.
Note: There are many variables that affect neutralization and dilution of chemicals discharged
through a system. Professional assistance should be employed in analyzing the effluent and the
necessary maintenance service.
Orion Trap Door Installation