The Fairmount Waterworks: An Engineering MarvelAshlee Anderson21st January 2014

MEAM 536 Viscous Fluid FlowUniversity of Pennsylvania

ABSTRACTConstructed prior to the industrial revolution, The Fairmount Waterworks in Philadelphia is a striking example of phenomenal industrial and mechanical design. Designed and built between 1812 and 1872, it served the city for over a century until it was decommissioned in the 1900’s. In addition to winning praises for its design and becoming a popular tourist attraction, the waterworks has been renovated and is now home to a restaurant and an interpretive center that explains the waterworks' purpose and local watershed history.

INTRODUCTION

In response to outbreaks of yellow fever in the 1700’s and the lack of a reliable source for putting out fires, the Center Square Waterworks, a steam-powered pumping plant, was built to distribute water from the Schuylkill River on the western edge of the city. Developed by Benjamin Latrobe, this system utilized two steam engines (in series) to pump water from the river into two wooden tanks with a capacity of a mere 57,000 gallons. From there, the water was gravity fed into a series of wooden water mains to serve the city. Inefficient and riddled with problems, the system was replaced after a decade with a larger, more efficient plant, namely the Fairmount Waterworks.

THE STEAM ENGINE

The initial Fairmount Waterworks employed steam engines to power the pumps. With the hopes of overcoming the problem of breakdowns, the Fairmount facility housed two engines, a low-pressure Bolton & Watts style engine built by Samuel Richards, and a high-pressure Columbian noncondensing steam engine built by Oliver Evans, so that even if one were inoperable, the city would never be without water.The low-pressure Watt engine derived its power from the pressure of the atmosphere acting against a vacuum produced by the condensation of the steam. It was initially operated at 2.5 psi, which was increased to 4.0 psi after the flue of the chimney was enlarged. The high-pressure engine used steam above atmospheric pressure to push against the atmosphere

in a similar way that the low-pressure engine used the atmosphere to push against a vacuum. The steam from the high-pressure engine was exhausted into the air at the end of the stroke and thus the engine did not require a condenser. This 100-horse power engine withstood pressures up to 220 psi, which made it efficient, dangerous. Each engine was connected to vertical double-acting force pumps that were connected to a single discharge pipe in the basement level of the engine house. The engine house was also equipped with adjustable valves to control the water flow based on the engine being used. Both engines together drew water from the Schuylkill River and pumped it up 96 feet to the reservoir, which was able to store 3 million gallons of water. Five wooden distribution mains, each with a six-inch diameter, led to the cast-iron distribution chest at the Centre Square works. The water then flowed as before through the already established distribution pipes to hydrants, pumps, business establishments, and dwellings in Philadelphia.Though the steam engines were efficient and considerably reliable, they were expensive and created a dangerous environment for those who worked in the immediate area. After two explosions, three deaths and many thousands of dollars spent, and alternative system was considered.

WATERPOWER

As a solution to the problems created by the steam engines, the Schuylkill was dammed in the early 1800’s in order to utilize the river itself as a source of power. Ariel Cooley was employed to build the dam, which consisted of a 1204 foot long crib dam from the west bank and an earthen mound dam built to extend 270 feet out into the river from the east bank. The millrace and space for the mill house on the east bank were blasted out of solid rock. The cribs were built from large logs that were floated to the appropriate spot in the river and filled with stone until they sunk. They were then fastened to each other and to the rock bed at the bottom of the river. The mound dam was constructed from earth and quarry spalls, and was built on the part of the river bed that had 11 feet of mud above the rock bottom, so chosen because it was calculated that it would be too difficult to anchor cribs in that location.The dam was created at an angle to allow ice to break up in the winter, and a canal and lock system was constructed on the west shore so the dam would not hamper river traffic.

WATERWHEELS

The dam, which is actually a spillway since it allows water to flow over it, was constructed to direct water around the back of the pump house and through the building, turning giant water wheels and driving the pumps.

Frederick Graff designed the mill house in such a way that the revolutions of the eight15-foot breast waterwheels were visible to the public, which made the mill house an irresistible tourist attraction. The lower section of the building was divided into twelve apartments for eight individual forebays and four pump chambers containing two pumps each. The first three wheels were of wood and the remaining five were of cast iron with wooden buckets. The speed of the wheels varied from 11 to 14 rpm, and capacity of the pumps varied from 91.08 to 121.4 gallons per revolution, supplying more than 5 million gallons per day. Though a vast improvement from the steam engine, the waterwheel was not without fault. The high tide of the Schuylkill posed a threat to the efficiency of the waterwheel as twice a day the backwater would cause the wheels to slow down significantly or even stop spinning altogether.

TURBINES

By mid 1800’s a Jonval turbine was installed as an experimental solution to the limitations presented by the waterwheels. The Jonval turbine is designed such that water descends through fixed curved guide vanes that direct the flow sideways onto curved vanes on the runner. The runner was 7 feet in diameter with 30 buckets and operated at 44 rpm. Added gears reduced the speed to 12 rpm in order to power a reciprocating force pump. The turbine, unaffected by the tide of the river, was three times as efficient as its predecessor, raising 1,685,016 gallons in 24 hours. A new mill house was built alongside the mound dam to facilitate the addition of three larger Jonval turbines to the facility and provide a greater supply of water for the growing city. Additional reservoirs were added on Morris Hill above the water works and by 1836 there were four reservoirs with a capacity of 22,031,976 gallons.

CLOSURE, RE-OPENING AND RENOVATION

As the population of the city increased, the waterworks expanded to meet the need. With the expansion of the city came the pollution of the river, which persisted despite efforts to acquire land upstream to prevent the construction of manufacturing plants along its bank. Although the waterworks had been able to keep up with increasing demand by implementing new turbines and improving their distribution system, it was almost impossible to increase the landmass on Fairmount in order to add a filtration system to the reservoirs, which would’ve been needed to compete with the emerging sand filtration systems of the newer and more technologically updated facilities that were emerging around the city.Consequently, the Fairmount Water Works was out of service by the early 1900s. The mill and engine houses, which birthed one of Philadelphia’s greatest engineering marvels, were handed over to the mayor of the city and became home to a public aquarium, which was later replaced by an indoor swimming pool. The land that housed the reservoirs atop "Fair Mount" was given to the Fairmount Park Commission for the construction of the Philadelphia Museum of Art.Though decommissioned, the waterworks remained embedded in many Philadelphians' image of the city and has been recognized as a national treasure by the federal government and by two professional engineering societies. In 1975 the American Society of Civil Engineers declared Fairmount Waterworks a National Historic Civil Engineering Landmark and on May 11, 1976, it was designated a National Historic Landmark by the U.S. Secretary of the Interior. In 1977 the American Society of Mechanical Engineers made the waterworks a National Historic Mechanical Engineering Landmark.

Attempts have since have been made to return the waterworks to its previous position as an engaging tourist attraction. The buildings, now restored, have been renovated as a hands-on science and environmental educational and interpretive center created by the Philadelphia Water Department. The Fairmount Waterworks has now become the region’s premier urban environmental education destination and is recognized as The Delaware River Basin’s Official Watershed Education Center and Gateway Center for the Schuylkill River National and State Heritage Area. For the general public, as well as for those with engineering or technical interests, The Philadelphia Waterworks, once considered "the Mecca of the hydraulic engineer”, has remained a unique technological and civic wonder.

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