Water Supply: the Present Practice of Sinking and Boring Wells / With Geological Considerations and Examples of Wells Executed

by Ernest Spon

[Figs. 87 to 91] show good methods of forming tube or pipe joints both in cast and wrought-iron, when not screwed.

Figs. 87-91.

P. S. Reed, an English mining engineer, gives the following instance of replacing defective tubing in a boring which had been pursued to the depth of 582¹⁄₂ feet, but which, owing to circumstances which were difficult to determine, had become very expensive, and made slow progress.

The 582¹⁄₂ feet had been bored entirely by manual labour; but Reid recommended the erection of a horse-gin, in which the power was applied to a 40-inch drum placed upon a vertical axle, the arms of which admitted of applying two horses, and men at pleasure, the power gained being in the proportion of one to ten at the starting-point for the horses.

Upon the upright drum a double-ended chain was attached, which worked over sheer-legs erected immediately over the hole, so as to attain an off-take for the rods of 60 feet, and so as that, in the act of raising or lowering, there might always be one end of the chain in the bottom, ready to be attached, and expedite the work as much as possible.

These arrangements being made, it was soon found that there was a defect in the tubing which was inserted to the depth of 109 feet, and the defect was so serious, in permitting the sand to descend and be again brought up with the boring tools, as to render it very difficult to tell in what strata they really were; this increased to such a degree as to cause the silting up of the hole in a single night to the extent of 180 feet, and it occupied nearly a fortnight in clearing the hole out again.

On carefully examining into this defect, it appeared that the water rose in the hole to the depth of 74 feet from the surface; and that at this point it was about level with the high-water mark on the Tees, about two miles distant, with which it was no doubt connected by means of permeable beds, extending from the arenaceous strata at a depth of 100 feet.

On commencing to bore, the motion of the rods in the hole caused the vibration of the water between a range of 40 feet at the bottom of the tubing, and so disturbed the quiescent sand as to cause it to run down through the faults in the lower end of the tubing.