66. Every underground tank installed shall be situated at least 1 m, measured horizontally, from any building, from any tank and from the storage area boundary and at least 75 cm, measured horizontally, from the inside wall of the excavation. Its installation shall prevent the loads carried by the foundations or supports of a building from being transmitted to the tank. In addition, from the footing down to the bed of the excavation, no earth shall be removed beyond a line delimited by a 45 º slope.