Chapter 16 of The Water Works of the City of Philadelphia: The Story of their Development and Engineering Specifications
Compiled in 1931 by Walter A. Graf (Staff Engineer, The Budd Company, Philadelphia), with the assistance of Sidney H. Vought and Clarence E. Robson. This online version was created from an original volume at the Historical Society of Pennsylvania, Catalog No. WZ 23591 (4th Fl. Folio).
Walter Graf History Home Page
(With Notes on the Text, Preface, and Acknowledgements)
Reading the Preface will give a quick overview of the beginnings and expansion of the Philadelphia water system.
NOTE: The Torresdale Works is now known as the Samuel S. Baxter Water Treatment Plant.
The Torresdale Station is the largest and the chief of the filtering plants and pumping stations forming the Philadelphia Water Works System. It is also the largest pumping and filtration plant of its kind in the world. It occupies an area of over 200 acres with sufficient ground available to provide for future extensions.
This station and the Lardner’s Point pumping station were placed in service at approximately the same time and were the results of a long period of study and planning by the Water Bureau for the improvement of Philadelphia’s water supply, particularly as it applied to filtration. In order to obtain the best possible results on a work of that magnitude and importance, a special bureau known as the Bureau of Filtration was organized on August 1, 1902, under the leadership of Mr. John W. Hill, as chief engineer. The great Torresdale filter plant was the fourth filter plant of the city to be finished. Daniel J. McNichol of Philadelphia was the contractor who built this plant and on January 23, 1902, work was started on the land appropriated to the Water Bureau by the City. The plant began operating in 1907.
The station is admirably located on the Delaware River approximately 11 miles upstream from the center of the city, in the section known as the 41st Ward, very close to the northeastern boundary defining the city limits. The station consists of a coagulant basin and coagulant dispensing house, intakes, low lift pumping station, preliminary and slow sand filters and a filtered water basin. The unfiltered, but settled or sedimentated Delaware River water, is pumped through an 11‑foot riveted steel conduit encased in a six-inch layer of concrete into the preliminary filtration system. The water is then directed to the slow sand filters, where the filtering process is completed, and thence to the filtered water basin. From this basin it is drawn as required through a conduit leading to the Lardner’s Point pumping station where the necessary pressure is applied to direct the pure water into the various distribution systems. Before the filtered water passes into the conduit leading from the storage basin to the pumps, it is treated with a chlorine solution in order to decrease the bacterial content which may have passed through the filters.
The original station consisted of 55 covered sand filters rectangular in shape, 23 filters being 140 feet 8 inches by 235 feet 8 inches, and 22 filters being 133 feet 2 inches by 253 feet 2 inches. Each of the 23 filters has an area of approximately 32,500 square feet or 0.747 acres net filtering area at the normal sand line, while each of the 22 filters has an area of approximately 33,000 square feet or 0.758 acres at the normal sand line. At a nominal filtration rate of 3 million gallons per acre per hour these filters with an average area of three-quarters of an acre were originally figured to yield a total of approximately 100 million gallons per day with all filters operating to capacity. Sufficient land was originally acquired by the City to extend this plant, ultimately to a capacity of 300 million gallons per day figured on the same basis. Provision was made in the original layout of the whole plant for the installation of preliminary filters to treat the water during periods of excessive turbidity.
The general construction of the filters is similar to those at Upper and Lower Roxborough and the Belmont filtration plants. Where the floors were built over fills, expanded metal of 3‑inch mesh No. 10 reinforcing steel was embedded in the concrete inverts. The arrangement of the regulating valve houses is similar to those at Upper Roxborough and Belmont. As in those plants a single building located at the end of the dividing wall between two filters contains a combined dry chamber for the inlet regulating apparatus for both filters and a separate wet outlet chamber for each filter. The raw water to supply the filters is taken from sedimentation basins built along the Delaware River by means of low lift pumps and is delivered to the several courts through a number of lines of 48‑inch cast iron water mains. The main drainage of the plant is carried generally from the northeast to southwest by means of a sewage system discharging into Pennypack Creek.
The filtered water basin is rectangular in plan, measuring 601 feet 10 inches by 762 feet 2 inches, and has an available depth of 15 feet and a capacity of 50 million gallons at the normal line. In general construction, this basin is similar to the filters, except that the piers supporting the vaulting are squared their full length and not battered at the base. The filtered water passes into the filtered water basin at one corner through an inlet gate house and out through a concrete conduit eight feet in diameter. The main contexts leading to and from the basin are built of concrete with expanded metal reinforcements, and are 10 feet in diameter. The water, upon leaving the basin, passes to shaft No. 1 of the filtered water conduit, and thence by gravity to the Lardner’s Point pumping station.
To learn fully the characteristics of the Delaware River water a testing station was established in 1901 in the old Harrison Mansion. This testing contributed in a large measure to the ultimate success achieved by the main station. The test filter was located in the tower of the mansion house and was supplied from a small pumping plant consisting of a gasoline engine and two triplex pumps located in a frame building especially built for them.
One of the principal features of the Torresdale filtration plant and the Lardner’s Point pumping station is the connecting link between the two which is known as the Torresdale conduit. This conduit carries the filtered water from the Torresdale filter plant to the Lardner’s Point pumping station. It is built for its entire length in a tunnel through solid rock and connects by vertical shafts at its opposite ends respectively with the filtered water basin and the pump wells in the pumping station. The conduit is circular in section, of 10 feet 6 inches inside diameter, and is 13,815 feet in length from center to center of the end shafts. Its rated capacity is 300 million gallons per day. At the Torresdale end the bottom of the conduit is 98.68 feet below mean high water, or 115 feet below the surface of the ground; while at the Lardner’s Point end it is 88.14 feet below mean high water or about 93 feet below the surface of the ground, thereby providing an upgrade to the pumping station of nine inches per 1000 feet. The work of building the tunnel was carried on simultaneously from 11 shafts, two end shafts which were permanent, and nine temporary working shafts. Headings were driven in both directions in all the working shafts, and in one direction only from each of the permanent end shafts. Active work on this conduit was begun September 23, 1901, and it was reported finished by the contractor in 1904.
The orderly progress of the construction of the Torresdale works was seriously delayed due to the resignation of John W. Hill, the chief engineer, and the working out of various recommendations made by a group of engineers who were investigating the construction of the filtration plant at this time. Not until 1907 was the pumping station for supplying water to the filter beds completed.
In 1907 contracts were awarded for preliminary filters designed to increase the capacity of the slow filter beds from 3 to 6 million gallons per acre per day.
In 1901 or shortly after decision was made to install additional filter beds at the Torresdale plant in order to supply the Queen Lane district with filtered water from Torresdale. For this reason the number of filter beds at Torresdale was increased from 55 to 65.
The Torresdale pumping station was equipped with steam-engine-driven centrifugal pumps, then the most advanced units of modern and efficient pumping equipment. The original installation of 1907 consisted of three 40 million gallon pumping units, two driven by compound vertical engines built by the R. D. Wood Company, and one driven by a compound vertical Bates engine built by the Allis-Chalmers Company. The installation of these three units was quickly followed by four additional R. D. Wood units of the same capacity. The interior of the Torresdale pumping station 1907-8 is the subject of the photograph of FIGURE 58 and the unit in the foreground is one of the R. D. Wood units. In the year 1907 the Torresdale plant filtered an average of 60 million gallons a day.
In 1908 additional equipment was found necessary as follows: three DeLaval 75 K. W. turbo-generators; two DeLaval turbo-centrifugal pumps each of 2.5 million gallons capacity, for supplying wash water for filter cleaning purposes; and two DeLaval turbo-centrifugal pumps each of 5 million gallons capacity (for pre-filter sand washing), and one Deane motor-driven triplex pump. A slight change in this small auxiliary pumping equipment was made during the years 1909 and 1910, by eliminating one of the 2.5 million gallon DeLavals and the Deane triplex. No substitution was made for the DeLaval, but a 3 million gallon Worthington compound duplex pump was installed in place of the Deane pump for emergency use in sand washing. In 1909 additional primary pumping capacity was found necessary and a DeLaval 50 million gallon turbo-centrifugal pump was installed.
During 1912 the Torresdale filters were put to a severe test by an unusually turbid condition of the Delaware River, and the state of the filters during 1913 demonstrated the necessity for a sedimentation basin which was subsequently built. It was finished in 1916. An index to the work done by a filter plant may be obtained from the records which show that during 1920 approximately 7,000 tons of mud were removed from the raw river water by the Torresdale filters alone.
When in 1901 the Committee of Experts recommended that the Queen Lane districts be supplied with filtered water from the Torresdale filter plant and the Lardner’s Point pumping station, the Committee also recommended the provision of a reservoir at Oak Lane.*
This recommendation was adopted, the reservoir was designed, and a contract for its construction was let on December 23, 1901 to the R. A. Malone Company of Lancaster, Pa. Its construction was started April 14, 1902, and it was completed in 1904, but was not placed in actual service until 1909. This reservoir has a capacity of 70 million gallons and consists of two basins of equal capacity, with a normal water depth of 20 feet 6 inches at a height of 210 feet above city datum. It is situated on the east side of 5th Street, between Chelten Avenue and 65th Avenue.
In 1926, a new pumping station known as the Oak Lane Booster or High Service Station was erected on the 5th Street and Chelten Avenue corner of the reservoir site to boost the pressure of the water above that of the reservoir, in order to adequately supply the higher areas of the Oak Lane and adjacent districts. Part of these districts had previously been taken care of by the Suburban Water Company, an independent company whose distribution system in this section was taken over by the city in 1926, at a cost of $358,525.60. The original equipment of the new station consisted of two Fairbanks-Morse, 7.5 million gallon per day, single-stage, double-suction centrifugal pumps and two 150 H.P. 1,200 R.P.M. A.C. motors; and one Fairbanks-Morse 10 million gallon single-stage, double-suction, centrifugal pump and a 350 H.P., 1,200 R.P.M. 2,200 volt motor. Two units of this equipment are in nearly constant service today (1931), and in order to provide a reserve unit for cases of emergency, a new 15 million gallon unit is now in process of installation.
A contract was let in 1920 for six 500 horsepower pumping engines of the Ames single cylinder vertical uniflow type for addition to the Torresdale Pumping station. The first one of these engines was installed and placed in service the same year. The installation of the last one of the six was completed during 1922. They were connected directly to the original centrifugal pumps used in this station. The installation of these engines instead of the more modern electric motor-driven units which had already proven their superiority and greater efficiency was apparently an error of judgment; for the engines gave trouble constantly, and so serious did the difficulties become that approximately five years later they were discarded in favor of the electro-centrifugal equipment.
An additional emergency pumping main six feet in diameter was laid from the pumping station to the filter plant in 1922, as an insurance against an absolute shut down in case of an accident to the original main.
The passing of the steam-driven pumping engines in this plant came in 1926 when there was made an initial installation of four 50 million gallon Fairbanks-Morse single-stage centrifugal pumps each driven by a 600 H.P., 650 R.P.M. electric motor. Two more were installed during 1927.
During 1929, all steam equipment no longer required, such as boilers, water softeners, feed water heaters, overhead coal bunkers, ash handling apparatus, etc., was removed, and the space formerly occupied by it made available for the installation of high capacity electrically-driven pumps. The Torresdale pumping station as fully electrified in 1930 is pictured in FIGURE 59. By reference to the map of Water Works Stations at the front of the volume one can gain an idea of the large portion of Philadelphia served by the great Torresdale filtration plant and the Lardner’s Point pumping station. It would appear to be fully half of the city.
* The earliest known reference to the building of a reservoir in the Oak Lane district was in 1884 when the Water Bureau cited its necessity and recommended that it be built at Twelfth Street and Olney Road, now Olney Avenue. Nearly twenty years elapsed before this suggestion was seriously considered as probably having value as a compensating reservoir to be used in conjunction with the new filtration and pumping systems, then in process of designing and building, particularly for the Torresdale and Lardner’s Point stations.