IMPROVEMENTS AT GRAND RAPIDS
Considerable improvements have been made at Grand Rapids, Mich., to the waterworks plant and further extensions of the flood-work under the direction of L. W. Anderson, city engineer. In a paper by P. M. Louwerse the new re inforced concrete standpipe is fully described as follows:
CONCRETE WATER TOWER.
A water tower of rather unusual type has been constructed in Grand Rapids. Its construction was recommended by Hazen and Gray in their report on the improvement cf the waterworks system. It was designed by Geo. J. Davis and myself under the direction of L. YV. Anderson, city engineer. It is located in a part of the city which is rapidly becoming a most desirable residence district, and this, together with the fact that the location is a little more than 4 miles from the pumping station, and the main which was to supply the tower also supplies the large district lying between the tower and the pumping station made a special construction necessary, it being a resident district made it necessary that the structure possess as much architectural beauty as possible. Its distance from the pumping station, and the fact that it was to be supplied by a main which was also a distributing main made it necessary that the tank be protected from the frost on account of the great fluctuation which would necessarily take place in the height of the water during the different times of the day. Reinforced concrete was decided upon as the most desirable material, and the plans were drawn for a reinforced concrete tank 50 ft. in diameter and 50 ft. high supported on a substructure consisting of a reinforced concrete floor on concrete columns ,10 ft. long resting on a foundation of concrete inverted arches. The tank and substructure were inclosed in a casing tower 3 ft. outside of the tank and covered by a dome. The local contractors were afraid of the reinforced concrete tank construction, the specifications for which called for its being completed in one continuous operation, and we were unable to get bids. The plans and specifications were gone over again by myself and a steel tank substituted for the reinforced concrete otic and several minor changes made.
The contract was divided into two parts, one comprising all of the reinforced concrete work; the other, all of the steel work and pipe and pipe fittings. The concrete contract was let to J. P. Rusche, a local contractor, and the steel contract to The Rodgers Boiler and Burner company, of M ttskegon.
The inverted arches of the substructure were designed as cantilever footings and reinforced near the upper side so as to make the footings continuous. The arches have a span of 7 ft., are 24 in. thick at the columns and 12 in. at the crown. They are reinforced under the columns near the lower side with jffs-in. square bars spaced 5 in., centre to centre both ways and 6 ft long. The reinforcing between the columns is near tile upper side of the arches and consists of Vft-in. square bars spaced 6 in. centre to centre both ways. These footings as designed spread the weight of the structure over the entire base, so as to give a loading of 4,300 lb. per square foot on the soil, which is a dry clean sand. This sand was reached by excavating about 7 feet through clay. The foundation, which contains about 175 cubic yards of concrete and 41,000 pounds of reinforcing steel was put in in one continuous operation, about 20 hours being required to do the work.
The columns are 24-in. square, with the corners chamfered. They are reinforced with 8 vertical bars in. square, hound together with a wire fencing of number to gauge-wire having a 4-in. mesh. This fencing was thoroughly wired to each vertical rod and a lap of 9 inches was used. The formula used in designing the columns is that of Considere P=FAc -f Y (As + 2.4 Ah) where
P=resistance of column.
F=unit stress in concrete in lbs per square inch.
Ac=area of concrete in square inches.
Y=eiastic limit of steel.
As=area of vertical reinforcing in square niches.
Ah—area of hooping metal in square inches per vertical inch X 2 II R where R=radius of hooping circle.
Each column was built in one continuous operation and contained about 2 1/2 cu. yds. concrete.
The floor and girders were so designed as to necessitate their being built together in one continuous operation, the total depth of the girder being measured from the top of the floor-slab to the bottom of the girder. The inside gilders arc 12 in. wide and 36 in. deep and are reinforced with 74-in. square bars. The area is 7 ft., centre to centre of columns.
The outer girders, which have a span of 12.8 ft., are 24 in. wide and 36 in. deep. They are reinforced with it $4-in. square bars in the bottom and are made continuous over supports by bending up eight of these rods near the point of contra-flexure, so as to bring them near the upper side of the girder over the supports and adding three straight bars )4square about 8 ft. long near the upper side over the support.
The floor-slabs are reinforced in both directions near the bottom, by )£-in. square bars spaced 9 in., centre to centre and near the upper side over the girders by 5/8-in. square bars 5 ft. long and spaced 5‘4 in., centre to centre. The slabs are 11 in. thick.
As stated above, the floor-slabs and girders were put in in one continuous operation, about twenty-four hours being required to do the work They contain about 135 cu. yds. of concrete and .uoo lb. of steel.
The casing tower is 12-sided, with a column at each corner and joined together by curtain-walls 4 in, thick. The columns from the base up to the lower annular girder, which is located on a level with the floor supporting the tank, are heavy and well braced to the inner columns, and, therefore. are not reinforced. They carry the weight of the casing towc and dome and take the wind-load which is transferred to them by the curtain-walls below the lower annular girder.
The columns from the lower girder to the top are reinforced with 8 14,-in. square bars and are designed to carry the weight of the upper girder and dome and, also, to transfer the wind-load carried to them by the curtain-walls to the upper and lower annular girders. They are stiffened by three intermediate girders placed about 15 ft. apart between the annular girders. The 4-in. curtain-walls are reinforced horizontally with 4-in. square bars spaced 8 in., centre to centre, so that they act as beams and transfer the windload to the columns.
The upper annular girder is designed to carry its share of the w’ind-load as transferred to it by the columns and, also, to take the thrust of the dome which springs from it. It is reinforced near its outer side with 11 J-in. square bars and near its inner side with 14 )4in. square bars.
The dome has a span of 57 ft. and a rise of to ft. It is 6 in. thick at the springing line and 4 in. at the crown. It is reinforced with wire fencing of number 10 gauge-wire of 4-in. mesh and, also, reinforced with a number of )4-m square bars. The top of the dome was plastered with a Jfj-in. coat of facing mortar applied as soon as the concrete was set. The facing mortal used was the same as that described below, under sand-finisn.
Above the upper girder is a parapet wall about 4 ft. high. This acts as a railing to surround an observation platform formed by the upper side of the girder and the base of the dome.
There is a hatchway in the dome which is reached by a reinforced concrete stairway of eight flights having fifteen steps each. The stairway is supported by cantilever brackets built into each column, each flight of stairs being designed as a beam reinforced near the lower side with five ^-in. square bars.
The lower annular girder, the upper annular girder and the dome were each completed in one continuous operation. The casing tower below the lower annular girder was completed in one operation. Above the lower girder the work was carried up about 6 ft. at a time, all twelve sides being brought up at the same time.
All of the ornamental work, as window-casings, the imitation stone blocks at the corners and the brackets under the upper girder, were built up with the rest of the concrete, special care being taken with the finish.
The “sand-finish” surfaces had the surface finished with facing mortar placed against the forms, backed with concrete and the two tamped together. The facing mortar was made up of one part of waterproof cement and two parts of sand. The waterproof cement was made of 4 lb. of Medusa waterproof compound mixed with one barrel of Portland cement—the object of the waterproof compound being to give a white color to those surfaces and make them stand out more prominently.
The “plastered surfaces” were finished by first sprinkling thoroughly with water for about fivehours and then giving the surface two coats of mortar. The first coat was put on with a float and troweled hard to secure a close union with the concrete. After this coat had set, the second coat of small gravel about the size of a pea mixed with mortar was thrown on with a paddle and left rough—making what is called a pebble dash surface.
All of the steel reinforcing used was furnished by the St. Louis Expanded Metal & Corrugated Bar company. It was rolled by the Carnegie Steel company, at Youngstown, Ohio, and inspected by the Robert W. Hunt company. The specifications required ail elastic limit of 50,000 lb. per square inch, with an ultimate strength of at least times its elastic limit; and an elongation in 8 in. of not less than 10 per cent. Test specimens of bending one and lyiu. were bent cold round a diameter equal to eight times their thickness to an angle of 90^ without fracture. 120,000 lb. of reinforcing was used in the construction.
There were three grades of concrete used, as follows;
Grade 1. For foundations, columns and other work over 6 in. thick to the bottom of the girders under the tank—I part Portland cement, 3 parts sand, and 6 parts gravel.
Grade 2. For the remaining portion of the work except the dome—1 part Portland cement, 3 parts sand, and 6 parts gravel.
Grade 3. For the dome—1 part Portland cement, 3 parts sand, and 5 parts gravel.
For grades 2 and 3 the largest particle of gravel was limited to I in. in the largest dimension.
For grade 1 the largest part of gravel was limited to 2 in. in the largest dimension.
There were 400 cu. yds. of grade 1 concrete used.
There were 620 cu. yds. of grade 2 concrete used.
There were 35 cu. yds. of grade 3 concrete used.
That portion up to and including the floor for supporting the steel tank was completed the first season, and during the winter the steel tank was constructed. The concrete up to this time was all put in place with the aid of a derrick.
For placing the concrete above this point, a scaffold made up of poles 80 ft. long and thoroughly braced together was used. Two elevators were built, so that the material could be carried up in wheelbarrows and wheeled off the elevator upon the runway built on the scaffold. This scaffold was entirely independent of the formwork, the forms all being braced from and wired to the steel tank. Steel bands made of turnbuckle and I’/i-in. round iron encircled the tank, and the wire was fastened to these. This made a very rigid construction, no jar whatever being felt from the men w-orking on the scaffold or wheeling material on it.
The form for the dome was supported by two timber trusses resting on the top of the steel tank. A platform of timber was built upon these two trusses and the ribs or stringers, consisting of 2×12 plank, with pieces nailed to the top of them to conform to the shape of the dome, w-ere supported from this platform. One-inch lumber w-as used to cover the joist. A portion of the form may be seen in one of the illustrations.
The steel tank is of the usual construction for such work. Butt-joints w-erc used for all vertical connections and lap-joints for all horizontal ones. There are tight courses of plates in all—the bottom course being made of 11-16-in. plate and the top one of 5-10 in. plate. A j4-in. plate was used to make the bottom of the tank and a 6x4x-in. angle was used to reinforce the top plate. There were about 257,000 lb. of steel used and the cost to the city was about 4 cents per pound.
I regret very much that I have tto accurate cost data on this concrete work. I have been able, however, to get at the total cost of the work through the courtesy of the contractor, Mr. Rusche. In checking up at the end of the first season’s work, he found that what we allowed him on an estimate of work done just covered within a very few dollars the actual cost of the work up to that time. In estimating this work I used a price of $fi per cubic yard for the concrete in the inverted arches, $10 per cubic yard for the concrete in the columns and $15 per cubic yard for the concrete in the floor and thin curtain-walls up to the bottom of the tank. The cost was to include form and the placing the concrete, but did not include the steel reinforcing, which was figured separately.
Taking the remaining cost and the cubic yard of concrete above the bottom of the tank, I find that the cost averages about $22 per yard. The concrete for the dome and upper girders, including the brackets, etc., no doubt cost a little more than this average while the remaining portions cost a little less.
The following is a list of the cost of the different items.
GOOD WATER POWER.
Grand Rapids, Mich., a city of 100,000 inhabitants, stands at the head of navigation on Grand river about 50 miles from Jake Michigan. At this point the river falls 17 ft. in 2 miles, thereby furnishing good waterpower for the factories in the city. The river, which after its long course and receiving the waters of so many tributaries, amongst which Indian creek is not the least, is liable to become flooded, and in former years has been the cause of considerable loss.
FLOOD PROTECTION WORK.
In order to guard against further damage, the extent of which may be judged of by the accompanying illustration flood-protection works on a large scale have been undertaken. These were interrupted for some time during the twelve months from March 31, 1907, to April l, 1908, and the high water interfered, not only with the repair work on the Ann street bridge, but, also, with the establishment of dock-lines. The work, which was practically suspended after the high water of April, 1907, has since been pushed on very rapidly. Its character will be understood by examining that on India Mill creek, which was practically completed by the latter part of September, 1907. The price paid for the protection that has been and is still being secured, including concrete cut-off and other walls, well excavations and the purchase of right of way since 1904, has amounted (with $812,514.01 contingent fund) to $232,655.94, with five contracts (including among other things the construction of a power dam, an embankment and dockline wall). When these contracts have been completed, Grand Rapids will be thoroughly protected against flood. The waterworks system, now
THE PRESENT SYSTEM.
a municipal supply, was originally the property of the Grand Rapids Hydraulic company, which succeeded a very crude system, the water from which was furnished by hillside springs up to 1861, when a brook was drawn upon. In 1864 a reservoir was built near the head of the brook, connections being made with additional springs in 1870. Two years afterwards a 30-ft.x20-ft. well was sunk to the underlying gravel strata, the water standing to a depth of 14 ft. The pumps were connected with this well by 150 ft. of 12-in. suction-pipe. The system was pumping to a standpipe, with a capacity of 235,000 gal.; distribution by 25 miles of iron and wood main. The present system, constructed in 1874, belongs to the city. The most notable improvement has been the construction of an addition to the pumping station and the installation of an additional pump in 1893, under the supervision of Peter Hogan, hydraulic engineer. The source now
SOURCE OK J5UPPLY.
is Grand river, the water being taken from a point distant 1 mile from the city. The system is pumping to a cement-faced granite, puddle masonry reservoir, with earth-filling, distant 1 mile from centre of Grand Rapids, 765.6 ft. above sea-level. The standpipes are two in number, No. 1 being 75 ft. high and 30 feet in diameter; No. 2, 60 ft. high and 50 ft. in diameter. No. 1, which is distant 1 mile from the business centre, has a capacity of 375,400 gal. and is built of steel riveted plate. No. 2, which is 3 miles distant from the business centre, has a capacity of 851,800 gal. and is built of steel riveted plates, inclosed in concrete. The builders of No. 1 standpipe were the Porter Manufacturing company; of No. 2, Rodger Boiler company and Joseph Rusche for the steel and concrete work respec-
QUKSTION OP FILTRATION.
tively. The quality of the water is fair. No system of filtration is employed: but at present a preliminary investigation as to installing a filter plant is being carried on. The pumping machinery comprises four pumps as follows; 1
triple expansion engine: 1 twin-compound: 2 single. Their aggregate daily capacity is 28,000,000 gal. The builders of the machinery were: The Xordberg Mfg. Co; Holly Manufacturing company, and Butterworth and Lowe. Of main (cast iron, 36-in., 4-in.), 172 miles are laid; hydrants (R. D. Wood & Co., Ludlow’ Valve Manufacturing company and Michigan Brass and Iron Works), 1,658; valves (Darling Pump & Valve company, Ludlow Valve Manufacturing company; Roe Stephen company), 1789; meters— owned by the city, 5,468; services (2-in.; ’/2-in. strong lead, 2-in. and upwards cast iron), 16,226. The pressure, domestic and fire, is the same, standpipe 90 lb., reservoir, 65 lb. The total consumption last year was 5.39239,095 gal.; daily, 14,728,615 gal.; per-capita, 147 gal. The cost of construction of the works to March 31, 1908, has been $1,902,662.70; bonded debt, $1,100,000; interest paid on bonds (average) 4.4 per cent, per annum; annual cost of maintenance, $44,731.69. The waterworks officials are as follows: Mayor, George Ennis; city clerk, John L. Boer; city engineer, Louis W. Anderson; superintendent and secretary, Samuel A. Freshney. During the year a 16-in. main was laid to the standpipe. It is recommended that this main should connect with the large main in Union street. A 20-in. main in Ottawa street was extended, so as to connect up several smaller mains and give better fire protection. A large and last section of 8-in. main was removed and replaced with I2in. Some 6-in., 8-in. and 10-in. pipe was also laid. A general remodeling of the plant is contemplated. Specifications are now in the hands of bidders for a 12,000,000-gal., vertical, triple-expansion pumping engine.