Volume Twelve - Pre-Victorian to the Present Day - further aspects - Petroleum-Storage Installations at Avonmouth and at Cardiff [1890] . . . .

As will be seen by the cross sections, Figs. 2, [Plate not available!] the banks generally were formed with a two to one batter on the river side, and a one and a half to one batter on the back, with a 4-foot top. The seat of the bank had the turf first pared off, and was then dug up one spade deep, after which the earthwork was barrowed up and put together by chopping and ramming in the usual way.

After waiting for several months any settlement was made up, the batters trimmed off, and the bank sodded over. A cess-ditch was formed at the back of the outer bank for the purpose of drainage, and provided with a small outfall clough at A, Fig. 1, details of which are shown on Figs. 3, 4 and 5. [Plates not available!]

The site was then thoroughly drained into the cess-ditch, by laying lines of 3-inch agricultural drain-pipes, 2 to 3 feet deep, every 30 feet, the trenches being filled with broken stone ; and the whole of the surface was subsequently covered with ballast and ashes.

At point B on the plan, a deep-water jetty was erected on the foreshore of the Avon, constructed of pitch-pine piles, ranging from 30 to 60 feet long, with timber walings, struttings, and deck, as shown in Figs. 6 and 7, where barges or vessels lie for either discharging or taking in cargo.

Tank Foundations

The petroleum is stored in bulk in large circular iron tanks, two of which contain 2,000 tons each, and the others 1,000 tons each, and it was important that a firm foundation should be secured for them. Trial borings showed the ground to consist of about 6 feet of brown clay on the top, with 30 feet of very soft black warp below (Fig. 8). It was found that piling would be too expensive, and ultimately the Author designed the following plan, which was adopted.

After taking off the soil, a timber and concrete raft, about 5 feet larger in diameter than the tanks, was constructed ; a layer of concrete, 18 inches thick, was first spread over the whole area, and upon this 12-inch by 6-inch timbers were laid across as shown, and another 18 inches of concrete put over the whole, thus forming a circular raft 3 feet thick and 68 feet in diameter for the large tanks, and 52 feet in diameter for the smaller ones (Fig. 14, Plate 7). [Plates not available!]