Seattle's Sewers Were Cracking All Over Town — and the City Engineer Blamed the Dirt

To the Editor: In today's POST-INTELLIGENCER the city engineer gives it as his professional and official opinion that the breakage of the sewers all over the city is due to percussion. Since the first discovery of the breakage the engineer has persistently refused to take natural and reasonable influences into consideration as the causes of the damage, but rather persists in seeking for visionary and unnatural causes to help him out of the dilemma.

At first a theory of dynamite explosion was advanced. The public mind was then agitated over the great strike. It was believed that under those conditions the public would believe in any hoax. Thus it was thrown out as a 'feeler' that perhaps some public enemy, presumably and preferably the union bricklayers, had floated dynamite into the sewers, and hence the breakage.

But the people of Seattle are accustomed to do their own thinking. They were not aware of having so pernicious a public enemy in their midst. Least of all would they for one moment suspect the trade unions of this city to be public enemies. The absurdness of that theory was so manifest that it was quickly abandoned, and a new one, though less malicious, but equally as ridiculous, is advanced.

Percussion Mr. Thomson concludes to be the cause. He is somewhat timorous about the advancement of the percussion theory. He tells us that 'some persons have been inclined to ridicule this percussion theory, as they cannot see how a shovelful of earth thrown on a pipe can break a pipe which will stand a strain of from 6,000 to 10,000 pounds.' To guard himself against that ridicule he cites a foreign authority, a Sir Joseph Bazalgette, who dropped an iron ball weighing fourteen pounds on an ironstone pipe and succeeded in breaking the pipe.

Now, what consolation does Mr. Thomson expect to derive from Sir Joseph Bazalgette's experiment? The ironstone pipe being the softer of the two substances, it naturally yielded to the percussion of the iron ball and broke. If the filling in of the sewers of this city were done with broken stone, gravel or lumps of hardpan, then, if thrown in carelessly, there might be something in the percussion theory. As shovelful after shovelful of dry, hard lumps is thrown on the center of the pipe, the dry lumps will jar the pipe and roll off to both sides. Continuous jarring is apt to cause a break, but as soon as the earth has reached a level with the top of the pipe, so soon is all danger of percussion passed.

But with wet, soft clay, there never is and never can be any possible damage done by percussion, for the very simple reason that the very first shovelful of wet clay thrown on top of a pipe sticks to the pipe and forms a natural protection against any damage from percussion. After the first half a dozen shovelfuls have been thrown in there is absolutely no jar on the pipe. As to the possibility of the first few shovelfuls having done the damage, that is nonsensical. The clay being soft, it is pliable and yields to the hardness of the stone pipe.

The city engineer attempts to aid his percussion theory by a tack-hammer illustration. He says: 'if you rest a tack hammer on the head of a tack it is pressing on the tack in the same way that the direct pressure is brought to bear on the pipes in testing them, and will never drive it into the wood, but if a child lifts the hammer and strikes the tack with it he will soon drive it in.'

It is hard to conceive how the tack-hammer illustration has any bearing on the point at issue. As a matter of fact you can force a tack into any substance by either driving or pressing, providing the substance is softer than the tack.

Leaving visionary and unreasonable causes out of consideration, there are but two causes to which the breakage of the sewer pipes can be attributed. One is poor pipe, the other the poor laying of the pipe. The first cause is out of the question, since it has been repeatedly demonstrated that the Denny Clay Company pipe is, if not superior, equal to any other made in the United States. The second cause, the poor laying of the pipe, is the sole reasonable cause to be taken into consideration, and for that cause the only person that can possibly be held responsible is the city engineer. Moreover, the very fact that he is so ardently engaged in finding visionary causes, and that he is extremely minimizing the damage done, proves that he knows that he was guilty and now tries to shift the blame.

Were this a paper written for a technical board of investigation, evidence could be adduced to put beyond a doubt that to the poor manner alone in which the work has been, and is being, done, can the damage be attributed. Since such evidence would necessarily involve technical descriptions and tedious details with which the general reader would have but very little sympathy, it is best to confine ourselves here to general statements only. No effort has been made to properly dig the trenches; in many instances no trenches at all were dug; the filling in has been done in the very poorest manner. And unless the construction of the two sewer tunnels is immediately placed under control of a man who is a trained constructionist, we will in a very few months hear the same reports from the tunnels that we hear today from the street sewers.