Covered Reservoir and Filtration Plant of Auburn
Centers of Reservoir and Filter Arches Made to Correspond— Roof Covered with Two Feet of Earth —Piers Eighteen Inches Square—Four Filter Beds
J. WALTER ACKERMAN
Water Department Watertown, N. Y., Formerly Superintendent of Water Board, Auburn, N. Y.
IN 1908, after the Commissioners of the Auburn, N. Y., Water Board had come to a definite conclusion that it was no longer safe for the city of Auburn to use an open water supply without filtration, they took such steps as were necessary to provide a filtration plant to purify the waters o f Owasco Lake, which is the supply that furnishes the City of Auburn. Plans were made in 1910 for a slow sand filter plant by the firm of Hazen, Whipple & Fuller, New York City. Then the voting population was asked to support a measure authorizing the water board to construct this filter plant. An antagonistic press and other adverse criticism prevented carrying out the plan at that time. However, the Commissioners decided that filtration was not defeated, but only delayed. So after some delay and some education of the public, the commissioners again sought to have an act carried which was done, the vote being about two to one in favor of filtration, but such a length of time had elapsed since the first design that the same firm was asked to go over their former plans and make such changes as the progress in the art would seem to dictate. The result was the redesigning practically of an entire filtration plant.
Arches of Filter and Reservoir Correspond
This plant consists of four filter beds of like area, the total filtration area being a little more than an acre and a half. As a part of this plant, in order that the filter might work at a continuous uniform rate, is a square well or reservoir, the subject of this sketch. This was so designed that the centers of the arches were actually the same as the centers of the arches for the filters, thereby, reducing the number of forms necessary. The dimensions are 182 ft. long by 156 ft. wide from center to center of outside walls, with a total depth of 18.75 ft. from the bottom to the Spring line of the arch.
PLAN OF ROOF STEEL REINFORCING
Construction of Reservoir
The excavation for this was in very hard material with glacial boulders embedded in hardpan, which required dynamiting to loosen it so that a shovel could excavate the same. Three side walls of the reservoir also were identically of the same section as those of the filter plant proper while the fourth one was a heavy reinforced wall, the reinforcing to take the earth thrust from the outside whenever the reservoir happened to be empty. On the three sides which have the same wall section as the filter the bottom of the reservoir slopes through four bents to the maximum depth. This is to save excavation and saves a great deal of concrete in the side walls as well as using the same forms as used for the filter.
The roof is groined arches and all parts are in compression with the exception of the deep wall heretofore mentioned. The roof is covered with two feet of earth and the interior has a baffle or maize for the water to circulate inside so that when chloride is used it is well mixed before it leaves the reservoir for the pumping station and into the distribution system.
The method of construction was to have a concrete mixer on the side of the reservoir at the head, somewhat above the maximum roof height and a row of piers were poured by means of a scaffold which was moved along for each row of piers.
Floors of Filters in Alternate Squares
The floors of the filters were laid in alternate squares and the forms holding these in place being screeded to these forms and when they were removed the alternate forms were filled in and screeds used to bring the filling squares to the same dimensions of the first ones placed.
(Continued on page 1111)
(Continued from page 1108)
The minimum thickness of the concrete on the floor midway between the piers was 6-inch and the maximum thickness under the piers was 13-inch. The piers thus were 18-inch square. The minimum thickness at the crown of the arches was 6-inch with a spring of 2-feet 3-inch. The piers were all very accurately located with transit and lines so that when the roof forms were inserted there was no tendency to rock a pier on its foundation.
Roof Formation in Four Parts Around Each Pier
The roof forms were made in four parts around each pier, breaking the joint at the crown on the arch each way from the pier.
The illustration on the cover of this week’s issue of FIRE AND WATER ENGINEERING shows the interior of the reservoir in its completed state. The illustrations accompanying this article are reproductions of the working drawings of the engineers for the erection of the reservoir and filtration plant.
The municipal water works of Akron, Ohio, of which H. H. Frost is superintendent, shows an increase in its revenue for 1920over that of 1918of $200,000, according to statistics in the budget report made recently. From the first of the year until November 1 the water works received $739,338.80 as compared with $664,079.79 in 1918. During 1919 revenues totaled $785,945.19.