The underground tank storage area consists of a concrete trough (1) with a cover (4) made of concrete slab (4), and in the trough are located the storage containers (4), pumps (9) and supervisory and/or regulating valves. The containers may be located in one section of the trough and the other equipment in another, or two troughs may fulfil the same function. The troughs or trough sections have means for pressure relieving.
