Water for the Allied Armies
To a large extent water for the allied forces on the continent is obtained from wells. The British territory is underlaid with chalk, and it is necessary to sink driven wells from 150 feet to 250 feet to reach the level of saturation. With two shifts the drilling progress on a 6inch hole varies from 20 feet to 00 feet a day, and the yield per well may range from 50 to 150 gallons per minute. In the Somme valley, British troops used river water, which was passed through purification plants mounted on harges. About four-fifths of the French army water supply in the region of Verdun was obtained from wells. Wells dug by hand, in addition to drilled wells, are also employed to some extent—one of them was put down to a depth of 65 feet. If time permits, these dug wells are lined for the upper 10 feet or 12 feet, and a curb two feet high is built around the top to prevent debris or waste falling back into the well. For dug wells a round section about 4 feet in diameter is common.