Designs for the Future Increasingly strict regulation of underground tanks has prompted many businesses to switch to above-ground storage tanks. Old-style AST's were once banned by local ordinances for reasons of fire safety. Protected AST's typically are made of an inner and outer steel wall with a thick concrete insulating layer in between. These tanks are now accepted by fire authorities for storage of gasoline, diesel fuel, and waste oil, though the tanks must be fenced off and cannot be used at retail gas stations. Despite these limitations, protected AST's are an attractive and economical option for industrial commercial equipment and fleet fueling.
Some manufacturers provide only a thin plastic liner to intercept any leaks from the primary tank.
Insist on two layers of steel. Ease of use. Top-mounted fuel pumps are often too high for easy access. The small additional cost of a side-mounted pump may be money well spent. Insist on spill boxes to catch drips and leaks from tank filling operations.