PREVENTING LANDSLIDES

Evening Star, Issue 20137, 30 March 1929, Page 23

PREVENTING LANDSLIDES

Profiting bv the experience of the hydraulic'mining industry, engineers of the California Department of Public Works are so controlling loose-sided hills that landsides are no longer a menace to highways (says Mr id. H. Dunn, in the ‘international Highways Magazine’). Up to the summer of i 927 each year's rainy season in Northern and Central California sent thousands of tons of earth and boulders on to the mountain highways, and all this material had to be removed by men with teams, motor trucks, shovels, and grading machinery. Now. however,, by thclimplc method of carrying water from mountain springs .I.oooft or more above the place where there is a possibility of a slide the danger is cliniim nated at less than one-fourth the cost of removing the slipped material from the high way. Danger to _ human . life and to automobiles also is removed. The water is conveyed from the spring in a Gin pip-., which is carried on a universal joint, so that the can be attacked from any angle. Where water from a higher elevation is not obtainable it is brought from river or creek by a pump caried on a motor truck and operated by the track engine. Two deep trenches, wide apart at the ton of the hill, and meeting in a large sluice box. passing under the highway, are washed ith the hydraulic jet. Then the boulders, gravel, and earth are wa.-uied down under the pave ment to the canyon below, permanently removing the menace of the slide. Such a method, with three men, can move approximately. 300 cubic yards a day. In one insta ice 25,000 .cubic yards of materia i war- handled through one sluice way beneath the highway by one man hand ling the nozzle. I '