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New water plant triumph of community involvement

Monday, June 10, 2002

By Lillian Thomas, Post-Gazette Staff Writer

It's bleeding-edge technology housed in what looks like an oversized 19th-century cottage, with stamped tin ceilings in the computer room.


 
 
Online Graphic:
Why microfiltration

   

 

The city's new $12 million filtration plant will take water from a 130-year-old reservoir and push it through tiny pores in polymer membranes inside a brick-and-stone building. Tucked behind Reservoir 1 in Highland Park, the computer-controlled facility, which is scheduled to go online later this month, recently won a historic preservation award, quite a trick for a brand-new building.

The mix of historic and high-tech is largely a legacy of a community that refused to accept a fate decreed by officials nearly 20 years ago for the man-made lake that is a centerpiece of the park but also one of the city's main storage facilities for drinking water.

Officials told residents they'd have to put a plastic lid on the 18-acre hilltop reservoir. Or maybe a floating membrane. Or drain it, fill it with concrete and store the water in tanks.

But the community said "no" -- no bunkers, giant waterbeds or 18-acre Tupperware lids.

Debate over the reservoir began when the state mandated in 1984 that all open drinking water supplies be covered by 1995. It went on and on, past the deadline. City water officials have been paying $300-a-day fines since February 2001 for noncompliance.

They didn't comply because the Highland Park community made a lot of noise and wouldn't accept local officials' assertions that there was no other way to meet state standards.

The Highland Park Community Club, city Councilman Jim Ferlo and residents fought the topping of the reservoir. Architect David Hance, a Highland Park resident, headed the quest for an alternative. The group proposed filtering the water being stored in the reservoir before pumping it out to customers. Though that wasn't feasible when it was first suggested nearly a decade ago, the reservoir lovers stalled long enough for technology to catch up and for the Pittsburgh Water & Sewer Authority to figure out a way to make microfiltration work in a large-scale system.

For its part, the authority decided to consider alternatives and worked with the community to come up with a solution that looks good and will produce the purest water in the city. It supplies water to 82,000 accounts, serving about two-thirds of Pittsburgh. Southern sections of the city are supplied by Pennsylvania-American Water Co. About 60 percent of the city authority's water passes through the Highland 1 reservoir.

John Kasper, senior project management engineer for the authority, has been coordinating the project. He's the one who figured out how to make the microfiltration process -- also called membrane filtration -- work on the scale needed for the system in Pittsburgh, which produces about 60 million gallons of treated water a day. He also worked with the community and coordinated the many contractors involved in the project.

The process has been employed in Europe, but not as much in the United States. When the city's system goes online it will be one of the largest in the country.

The concept is simple: Strain water through very small holes to clean off impurities. But it's the latest step in the evolution of water purification.

In 1872, Pittsburgh ended reliance on well water by building the Highland Park and Herron Hill reservoirs. Water went from river to pumping station to reservoir for days or weeks of settling out, then out to homes and businesses. It wasn't a bad system, but it meant more than 100 typhoid fatalities per 100,000 people every year.

Over the years, the process got more complicated, the water safer. Sand filters were added at the beginning of the 20th century, and chlorine treatment shortly afterward. Many supplies of "finished" water were covered or stored in tanks. But others remained in open reservoirs. Though the water in such reservoirs goes in clean, it can become contaminated by exposure to dirt, bird droppings and other contaminants.

With the new system, water will go from river to treatment plant to pumping station and up the hill beneath the reservoir. At times of peak demand some water would go straight to customers, never entering the reservoir. The rest would go into the reservoir, then, when needed, into the microfiltration plant, where it will be re-treated before being sent to the public.

The water is pushed through plastic modules -- long tubes 8 inches in diameter -- stuffed with 1,500 polymer membrane filters -- "think tiny plastic drinking straws," Kasper said. The water is pushed under pressure through the 0.1-micron pores of polymer and comes out purer than when it left the treatment plant. The process is fast, with water flowing through in seconds. There are 10 racks of 53 modules each, and racks go off-line frequently to back rinse themselves. That gets most of the gunk off. More thorough chemical cleanings will take place as needed, he said.

In addition to the cost of the facility itself, the authority will do $6 million to $8 million of work on its system, much of it repairs already planned but made necessary by the reconfiguration of the system.

Though the new facility costs more than the $8 million to $12 million estimated for buying and installing a floating cover, it's substantially less than the other options.

"Hard covers of various sorts looked like $50 million to $100 million," said Kasper. "Replacing the reservoir with tanks, instead of covering it, started at about $30 million and went up to $100 million, depending on size and location."

Jim Morgan, an architect with Urban Design Associates, said his firm had to design a building that would fit in with the park and surrounding neighborhoods.

He took a bit of inspiration from a bathroom.

"It seems somewhat mundane, but there is a small building along the walkway [around the reservoir] that has some architectural detail, a finial, a steep roof" that are echoed in the design of the water plant, he said.

The building was once the watchman's, Kasper said, and later was made into a restroom.

Morgan said he drew on the "architectural vocabulary" of homes in the area to create the water plant, which has elements of French Tudor but is not representative of a single architectural style.

The building had to accommodate a 50-foot tower -- technically the "hydraulic control structure" -- but Morgan knew that "a four- or five-story building would not look appropriate in a park; it would look like an office building in a suburban office park." He needed to design something that looked smaller than it is. So he created a building with two giant floors instead of four normal ones. Large windows, doors and dormers create the illusion of a smaller-scale building. Inside, details like stamped tin ceilings continue the 19th-century feel.

The building was given a historic preservation award by the Historic Review Commission and the city of Pittsburgh. But for Morgan the best compliment is when passersby ask workers if they had to gut the whole structure before completing the renovation -- confirmation that he's succeeded in designing a building that looks like it's always been there.

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