Underground tanks of glass-reinforced plastics (GRP). Horizontal cylindrical tanks for the non-pressure storage of liquid petroleum based fuels. Transport, handling, storage and installation of single wall tanks|Reinforced materials, Sleepers, Lifting, Cloth, Installation, Storage, Construction operations, Laminates, Transportation, Size, Plastics, Glass fibres, Depth, Pressure testing, Glass, Test pressure, Textile glass, Certification (approval), Excavating, Fuel storage, Bulk storage containers, Underground, Anchorages, Horizontal, Containers, Tanks (containers), Leak tests, Cylindrical shape, Thermosetting polymers, Materials handling, Visual inspection (testing), Petroleum products