ASSEMBLY AND PREPARATION FOR USE. - continued
Tank pads and berms may be lined with a heavy gauge plastic sheeting if soil permeability is a
problem at a particular site. Construction grade low-density polyethylene preferably with a fiber net molded in, is
acceptable. Care must be taken to adequately overlap and, if possible, seal the joints. Low-density polyethylene can be
heat sealed at the joints if time and site conditions permit it prior to the arrival of fuel to the area. Another acceptable
method of seal is to tape the joint with two to four-inch self-adhering plastic tape. A light earths or sands fills over the liner,
particularly over the tank pad is recommended. If a drain line penetrating the berm is used, a section of the liner must be
pierced and tied tightly with synthetic cord around the drain pipe or other wise sealed so as to avoid washout or leakage at
this point. Plastic self-adhering tape, overlapping the liner and the drainpipe may also be used. Sealing tape and plastic
sheeting are not supplied with the TPT.
For certain environmentally sensitive situations, a prefabricated polyethylene berm liner may be
procured as authorized by the Government. They are not part of the TPT supply under NSN 3835-01-288-4604. These
liners are described as follows:
Berm Liner, Size 4, 50,000 gal
Berm Liner, Size 5, 5,000 bbl
To prevent tank damage, tank pads must be free of rocks, sticks, and sharp
Berm drain valve must be in the closed position and opened only to drain the basin
when necessary. Failure to do so may result in a fuel spill escaping the berm.
Do not install fabric collapsible tanks on a slope in excess of 3°. They may tend to
creep in the direction of the slope causing tank damage.
5,000 Barrel Tank Berms. The dimensions of a 5,000 bbl. fabric collapsible tank are:
Dry: 68 ft. 6 in. x 68 ft. 6 in.
Filled: 6 ft. 8 in. X 66 ft. X 66 ft
The minimum dimensions of the berm should be:
From toe of berm to tank wall when filled, 4 ft.
Berm height, to contain full tank with 1 ft freeboard, 5 ft. 6 in.