Seattle's Broken Sewers Were Shoveled to Pieces, Engineer Says

City Engineer Thomson has concluded from his investigation of the broken sewer pipe that the breakage is due not to explosion from within, as was first supposed, but to percussion from without—lack of care in backfilling and the use of some lengths of soft-burned pipe in wet ground. Thomson took a Post-Intelligencer reporter to the sewer opened on Kenny Street, south of Remington Avenue, and showed the nature of the breaks. At that point there are two groups of broken pipes separated by a stretch of sound pipe run through a tunnel instead of laid in an open trench. In one group were twenty-eight lengths, of which three were broken into small pieces; twenty of the remaining twenty-five were apparently soft-burned and generally broken lengthwise in three or four places. The ground in both places is wet and clayey. Thomson said he had found nothing to support the explosion theory. He explained that a clod of wet clay dropped twelve feet onto a pipe would strike with many times its weight, and cited experiments by Sir Joseph Bazalgette showing that a falling iron ball could break pipe that had withstood heavy pressure. He will continue his examination through the week, extending it to pipe sewers in Ballard and Olympia, and will report to the board of public works next Monday.