COLLAPSE OF A STAND PIPE.
The Great Structure at Peoria That Broke Off at the Base and Let Out Over 400,OOO Gallons of Water—Interesting Description of the Tower and the Break.
[Reported Specially for FIRE AND WATER.]
THE ordinance under which the Peoria, Ill., Water Company built its works required that there must be a storage reservoir and two water towers, of a combined capacity of 20,000,000 U. S. gallons. Their flow line is at elevation 320 city datum, or about 220 feet above the general level at the court house. The towers were built on the top of the long bluff, which runs nearly parallel, and about a mile back from the river, and in somewhat open parts of the otherwise thickly built-up districts; (the line of the bluffs is nearly east and west) that at the upper end or on the east bluff being on higher ground, was made thirty (30) feet in diameter by eighty-five (85) feet high, and the other, or the west bluff tower, built near the corner of Hourkiand ave. and College st., was twenty-five (25) feet in diameter by one hundred and twenty (120) feet in height.
The plans and specifications for the entire works were prepared by Chester H. Davis, Mem. Am. Soc., C. E. The work of construction was placed in charge of E. H. Burlingame, C. E., who was made the president of the company, the reservoir and stand pipe construction being in the direct charge of Eugene Carroll, C. K., his assistant. The towers were built by the Porter Manufacturing Company, of Syracuse, N. V., and were completed and put into use about May 1, 1890. They were tight and apparently all right and never gave any trouble or cause for uneasiness until on Friday, March 30, at about 10:20 A. M., the one on the west bluff, from some cause not yet determined, burst with a succession of pistol-like reports, wrecking it completely and doing some, but not serious, damage to the buildings in the vicinity. One boy was killed, being crushed under the bent edge of falling sheets, and fifteen more people were more or less injured by being tossed about by the escaping waters.
The tower contained about 400,000 gallons, the water being somewhat below its natural level on that day, so that the water was not over 105 feet deep in the tower, causing a pressure at its base of from 46 to 47 pounds.
The day of the failure was warm, pleasant and the wind was blowing, but not strong, from the west ; the rate was probably not over six or eight miles per hour. The weather had been mild for two or three weeks and no ice existed in the tower.
There had been a slight leak at the top of the seventh course, thirty-live (35) feetfrom the base, on the northwest side of the tower, and workmen had been sent to examine, to make it tight if necessary, and to paint the discolored portions of the tower. It was found to be rusted up and tight, so no caulking was done. The man painting it had reached the ground but a moment before the break occurred. As this joint and the plates around it are all intact and unbroken, it is evident that the fault was not at that point.
The water was supplied to the tower from the avenue west of it, through a 16-inch cast iron main, entering the tower through its bottom plate.
A manhole was at the east side of the tower in the lowest, or first course, and it remains intact in the sheet, save that the bottom of the sheet is torn away through a few of its rivet holes, thus breaking off a portion of the bottom of the flange. The sheets built five feet courses, six sheets to the course. About one-third of the sheet only remained attached to the casting, and it, with a portion cf the second, third, fourth and fifth courses lie about thirty (30) feet southeast.
A careful study of relative positions of the pieces, as they now lie, of the condition and position of the holding-down bolts, the effects of the water and other facts bearing upon it, show that the rupture began on the north side of the tower, at or near a seam between the first and second courses, and its joint between two second course plates, and from there it tore upward to the right and to the left.
Some pieces, say one-fourth the arc at the immediate left (or easterly) side, were thrown varying distances to the street and yards beyond, in a north, northeasterly course beyond them. At the right, or westerly side, a piece three courses high (15) by forty (40) feet long, or more than half the circumference, was torn off down to the bottom rim of angle irons, was straightened out, lifted up about twelve (12) feet and thrown against the cottage one hundred (100) feet distant, and a little to the west-of south. The remaining quarter, containing manhole, and with some part of the fourth, fifth and sixth courses, was thrown fifty (50) feet east of southeast, with the upper course plates bent down on the top of those of the lower course.
Practically all of the tower above the sixth course was turned quarter way round, and fell almost due east, the joint between the seventh and eighth courses being about sixteen (16) feet from the base of the tower. The joint between the eighth and ninth courses was torn partly through the rivet holes for two-thirds of the circumference, and was stretched out to the northwest, and the end was due north from the base and fourteen (14) feet away from it.
As the tower fell the ladder is at the top near the east side, and pointing directly at its former position. The tower in falling was flattened to about six feet, and was broken most at the top from the fall.
Within the last month observations made on the tower showed that it was truly vertical.
The tower was built in level courses, with the lesser diameter downwards.
A large portion of the fourth, fifth and sixth courses (say 15 by 20 ft.) was blown west across the arc, cutting off cleanly a tree nine inches through, near the butt. A piece weighing several hundred pounds was thrown 250 feet southwest, and small pieces spread from west to northeast; the remainder, a piece, fifteen by fifteen feet, being dropped 75 feet northeast, cutting off near the bottom a tree seven or eight inches in diameter.
The following is an extract from the specifications, including everything which refers to the construction of the tower and the metal to be used in it.
SPECIFICATIONS FOR STAND PIPES.
The metal of the plates must be of a soft, homogeneous steel, unless otherwise specified, possessing a maximum tensile strength ol sixty-six thousand (66,000) pounds and minimum tensile strength of fifty-five (55,000) thousand ‘pounds per square inch, and bcofficially and legally stamped; must be smooth, truly and evenly rolled and uniform in size, and sufficently ductile to admit of rolling while cold around a radius of twenty (20) inches, without developing flaws, cracks, splits, or any other features which would render them unfit for the work in the opinion of the engineer. The plates will be inspected by the engineer, upon notification before being put into the pipe and before painting, and all improper plates will be rejected.
Where iron plates are specified the iron must be best quality tank iron, having a tensile strength of 48,000 pounds per square inch.
Test pieces of the plates will be made and broken by the contractor in the presence of the engineer, when he may desire, and at no extra expense to the purchaser.
They must not be less than the thickness specified.
The plates will be of such width that each course will build practically five (5) feet. Each sheet will be not less than twelve feet in length.
Burden’s “best-best” rivets must be used for the whole work.
All horizontal joints will be single riveted, and the vertical joint will be double riveted, unless otherwise specified. The diameters and pitch of rivets must be satisfactory to the engineer.
The manhole, plate, rings, etc., inlet pipes and flanges, and all other cast iron work, will be of good quality, of fine gray pig iron, and must be sound, strong, smooth and perfect castings, and properly coated.
The bottom plate will be of half-inch wrought iron with half-inch cover plates and butt joints, double riveted with three-fourths inch rivets, and double riveted to angle rings as shown, which in turn will be double riveted to the bottom course, seven-eighths inch rivets being used.
The flanges of the inlet and blow-off pipes will be bolted to the bottom plates, using lead or corrugated copper gaskets at all flange joints. The joints must be left water tight.
The bottom plates must be set in cement or grouting (one part Kosendale, or equivalent cement, and three parts sharp, clean, fine sand), and so that no void will exist beneath it, or in a mixture of asphaltum and bitumen, as desired and directed, by the engineer,
The bottom plate must be truly level and the first course plates truly vertical when set in place.
The stand pipe must be of the dimensions specified, at the least, inside diameter.
The bottom course will be an outside course, and those above will be alternately inside and outside courses, or bevel courses upon approval.
A suitable oval manhole 15 inches by 18 inches, or acceptable equivalent complete, and wrought iron lugs for holding down bolts, will be properly riveted to the stand pipe as above.
Twelve holding down bolts of best refined iron, provided witn washers, plates, alcove-nuts, lugs and steel pins, etc., and reaching to the bottom of the foundation will be furnished as shown on drawing for each stand pipe.
Lay all holes out carefully and accurately and punch with a centre punch, sharp and in perfect order, from the surface to be in contact, and so that the bevel of the hole may be away from the surface in contact.
Plates showing any indications of hardness or brittleness, .may be annealed after punching or rejected at the option of the engineer.
Plates having ragged holes or holes so much out of place as to require the use of the drift-pin will be rejected.
All plates must be planed to a slight bevel in a machine and be carefully calked with a round nosed teal and made perfectly tight. Lay all the work out so that each joint will come half way between those of the next course.
Where three plates join, the over-lap is to be neatly scarfed down while hot. Heat rivets uniformly and carefully and never set one when cooler than red-hot. The riveting must be done in a neat and workmanlike manner.
The following schedule gives thickness and data for riveting stand-pipe for west bluff, diameter 25 feet, height 120 feet :
Provide and construct balcony and crestings as shown by detail drawings o( iron.
A ladder fifteen inches witie of three-fourths inch round iron rungs, shaped as shown, will be riveted by suitable brackets, or braces, not more than ten feet apart, to each standpipe. The steps will be twelve inches apart, and begin nine feet above the water table.
They will project six inches except when drawn differently.
The side bars or ladder will be one-half by three and onetjuartcr inches.
After inspection which will be at the shop, each sheet must tie cleaned and painted, or dipped into a bath of hot asphaltum, and before being placed in the standpipe. There must tie no paint on surface in contact. After testing, the work will be given two coats asphaltum or lead in oil, to suit the engineer.
Paint alt other iron work three coats.
Paint all wood two coats.
The standpipe will be treated before receiving the final coats of asphaltum, by being filled w ith water, and by being allowed to remain full for such time as the engineer may deem necessary to satisfy himself that the work is water tight,
A study of the fractures shows that in nearly every instance ruptures in A vertical direction have been through the sheets rather than along the triple or double riveted vertical joints, and that, in most instances, transverse ruptures were through the rivet holes of the single riveted horizontal joints. A careful and thorough study of the case, with a hope of determining the cause of the wreck, is being made by the Superintent and by the company’s Consulting Engineer.
Those injured in the accident are doing so well it is thought that no serious or permanent injuries will result to any of them.
The foundation of the tower was left entirely uninjured, save that portions of the coping or water table stone which was put in in twelve pieces, were moved or broken. Three pieces, each weighing about too pounds, were carried about 150 feet south and east. The earth around the foundation was washed away for a depth of from three to five feet for a distance of twenty to thirty feet from the tower. It may be interesting to note that the inrer surface of the sheets shows a peculiar corjosion similar to that which has often been observed here in the cast iron and wrought iron water pipes, which it has been necessary to remove or repair on account of electrolysis. This corrosion takes the form of blisters or excrescences, generally elongated and globular in shape, with the longer axis vertical. These blisters are composed of a skin of brown oxide overlying what appears to be a thin coating of black oxide. Under this second coating the surface is pitted, often to a depth of an eighth of an inch. The surface at the pits when the oxide is removed shows a clean metallic appearance. The inside of the 16 inch cast iron inlet pipe, which was not painted, or coated, shows similar but larger blisters and pits. The blisters and pits appear to increase in number and size from the top toward the bottom of the standpipe, the small pits near the top, however, being almost as deep as the larger ones lower down.
The inner surface of the upper course of sheets, which is seldom wet, shows very little oxidation, and none of this character. The two next courses, which are alternately wet and dry, show this corrosion to a limited extent. The 16-inch branch feeding the tower is crossed by a double electric railway, which runs along the main for nearly a mile from the tower. All the principal mains of the system are paralleled or crossed by double-track electric railways. The same corrosion is observed in the tower on the East Bluff.