(a) An underground tank for Class I or Class II flammable liquids shall be located not less than the distance indicated in Table 776, measured horizontally from the nearest point of the shell to the nearest line of adjoining property that may be built upon and the nearest outside wall of any basement or pit, of which the floor is lower in elevation than the top of such tank. Where such location causes unnecessary hardship, an underground tank may be placed closer than the distance specified if enclosed, encased or otherwise protected from physical damage.
Table 776
MINIMUM DISTANCE FROM UNDERGROUND TANKS FOR CLASS I OR II FLAMMABLE LIQUIDS TO BASEMENTS OR TO LINE OF ADJOINING PROPERTY THAT MAY BE BUILT UPON
| Individual Tank Capacity Class I and II | Location if top of tank is above the lowest floor, basement, or part of any building which is not less than: | |
|---|---|---|
| 500 Gallons | 5 feet away | |
| 5,000 Gallons | 10 feet away | |
| 10,000 Gallons | 15 feet away | |
| 15,000 Gallons | 20 feet away | |
| Unlimited | 25 feet away |
Depth and cover
(b) Underground tanks shall be set on firm foundation and surrounded with soft earth or sand well-tamped in place. Tanks shall be covered with a minimum of 2 feet of earth, or shall be covered with not less than one foot of earth on top of which shall be placed a slab of reinforced concrete not less than four inches thick. When subjected to traffic or likely to be so subjected in the future, tanks shall be protected against damage from vehicles passing over them by at least 3 feet of earth cover, or 18 inches of well-tamped earth plus either 8 inches of asphaltic concrete or 6 inches of reinforced concrete. When asphaltic or reinforced concrete paving is used as part of the protection it must extend at least 1 foot horizontally beyond the outline of the tank in all directions.