The most significant technological change that Al Petrasek has seen in the pump technology industry in the last few years has been concrete volute pumps for stormwater pumping. The casing and suction draft tube of concrete volute pumps is cast in concrete, with metallic rotating parts.
“These pumps are incredibly rugged,” notes Petrasek. “They’re designed to handle high flows and have low to moderate heads. The heads will get excess of 500,000 gallons per minute per pump and can handle heads of up to around 150 feet or more.”
Petrasek serves as the vice president and national technical pump station lead for HDR Engineering, an engineering consulting firm. As such, he has two functions: one is to be a national resource for pump station questions, and the other is to help make additional infiltration in the Texas water conveyance market.
He has been assisting in getting the pumps up-and-running in Dallas, TX. “These are very common in Europe, and we have none in service in the United States, and only a few places in North America where they’re installed,” notes Petrasek. “These pumps are so reliable, that they’ve pretty much become the standard for nuclear power plants. When the power plants put them in, they typically don’t put in redundant units. If they need two pumps, they put in two–they’re that reliable.”
Looking down the hatch
Thus, the pumps are cost-effective, he adds. “Since they do have large flows, that means you can reduce the number of pumping units you can have, so, generally speaking, the fewer the number of pumps, the less expensive the pump station is going to be. Because of the way the pumps are built, maintenance–at least in stormwater applications–is simplified significantly, because these pumps have fewer shoulder shafts than the conventional vertical pump would.”
Petrasek says there is not one engineering and design solution that fits every situation in the United States. “When I think in terms of water resources management, it really becomes a project- and local-specific issue in terms of how you’re going to address it,” he says. “There are some areas here in north central and northeast Texas, where some of the municipal clients have what I call scalping reservoirs, so when a river comes up to flood stage, water spills over into some reservoirs they have, and then they use those reservoirs for drinking water supply.”
While smart and efficient pump systems aid in water resource management and improve water efficiency, newer pump technology is incorporating energy efficiency, as well as water efficiency, an inextricable link that is taking on more importance in these times. ITT Goulds Pumps points out that a single 75-horsepower (hp) pump uses about $20,000 in electricity annually. Worldwide, more than 2 trillion kWh of energy are consumed to pump and treat water and wastewater.
The company has manufactured pump technologies that are aimed at helping clients realize a 20 to 60% energy savings. One such technology is the company’s Flygt N-pumps. Its adaptive impeller was designed to enhance the ability to resist clogs that are commonly a factor in wastewater treatment with materials such as baby wipes, plastic, and rags. An extra blade can be added to the impeller to boost energy savings up to 50%.
Additionally, in contrast to traditional 12-pole mixer motors, the Flygt N-Pump uses line-started permanent magnet technology. In industrial plants, the average pumping efficiency is below 40%. Pump oversizing and throttled valves are two issues ITT considered in designing PumpSmart, a microprocessor-based variable speed drive made for pumps up to 700 hp that aids in adjusting to process and system changes. As part of a smart pumping system with embedded sensors and single or multi-pump controls, PumpSmart is estimated to produce up to 70% savings in life cycle costs.
PumpSmart continuously monitors and responds to pump conditions by providing automated control of the wastewater pumping process, fault monitoring read-outs, and reports on hours used, average power draw, and temperature, as well as other indicators.
ITT’s Energy Performance Services also helps optimize pump efficiency. In one such case in Wisconsin, ITT analyzed energy performance at Appleton Coated–a large paper manufacturer with more than 1,000 centrifugal pumps–and produced recommendations for 23 pumps that resulted in an estimated projected annual savings of $1.1 million.
In another case, PumpSmart technology played a pivotal role in addressing water and wastewater challenges in South Glens Falls, NY. The village prides itself on its picturesque beauty and historic qualities, exemplified in part by the 18th-century homes that line the Hudson River and in Cooper’s Cave, the inspiration for James Fennimore Cooper’s Last of the Mohicans.
It was also the site of a wastewater treatment system challenge. The system–which consists of six wastewater pumping stations–collects wastewater in South Glens Falls, and pumps it across the Hudson River to the town of Glens Falls, for treatment. Residents are supplied drinking water from a small plant that treats water from area wells and pumps it into a 1-million-gallon tower.
The wastewater facilities consisted of cantilever pumps placed in belowground shelters at the base of the holding ponds. Simple visual inspections required a village employee to climb down into the narrow 23-foot shaft with a spotter up above. Routine maintenance would entail a five-man crew and often take a full day to lift the pump out, perform the necessary operation, and place it back online. Repairs could take longer.
Maintaining the pumps had been a drain on resources, as the village has only eight public works employees who must tend to the entire village’s municipal needs. After village officials commissioned an engineering study, consultants recommended placing self-priming pumps above ground for easier access to reduce the manpower needed for maintenance and repair. However, the solution required larger, more expensive pumps that would utilize more power. Also adding to the expense would be the construction of new aboveground pumping stations.
A second opinion was solicited by Emerick Associates’ Brian Marshall, who determined that the first consultant’s finding (that submersible pumps would not fit through current shaft openings) was incorrect after he recalculated the measurements. He then recommended the village purchase 10 ITT Goulds submersible heavy-duty cast iron sewage pumps and 15 PumpSmart Automated Controls. The pumps are ITT Goulds 4NS 4-inch non-clog pumps, which are used in conjunction with the PumpSmart controller. A self-cleaning option enables the pumps to operate in reverse to remove obstructions without removing the pump unit. One backup pump was installed to cover all stations.
Village officials use the PumpSmart technology to regulate the pump speed through standardizing on one pump size, although each lift station has different requirements. It also reduces the need to inventory spare parts for different-sized pumps. The technology also enabled the village to better monitor wastewater levels in each pool by converting from a system of multiple floats–that were frequently hampered by clinging debris–to single electronic level transducers that accurately measure levels at each station.
Village Operations Manager Jack Dixon says the new installation–most of which he did himself (which saved money)–has dramatically streamlined maintenance. Previously, village crews had to physically check each pump and monitor the line for problems.
Now “If you need to get a pump out of there, you simply press a button, hook up a chain, and lift it out,” he says. “If your read-out shows no alarm, you can close the door and continue with other duties.”
Pleased with the results for the wastewater system, the village continued its efforts with the freshwater system. Upon Marshall’s recommendations, village officials upgraded the vertical turbine pumps with two new motors and outfitted each with PumpSmart technology, which allows the pump to “soft start” and gradually slow down to improve power efficiency and reduce wear and tear. The variable frequency drives also allow South Glens Falls officials to make adjustments for seasonal water demands.
Department of Public Works Superintendent Brian Abare has indicated he is pleased with the solution and recommends it for other municipalities facing similar challenges. The upgrades have enabled the village’s 3,400 to retain its scenic qualities while saving thousands of dollars in replacement and construction costs, as well as lower energy and maintenance costs.
The village saved approximately $24,000 less per pump station by using ITT Goulds submersible pumps and PumpSmart technology, rather than the originally proposed self-priming pumps. Monthly electricity costs have dropped by 30%, with an estimated energy savings per quarter per station of $800 to $1,600. Savings also were realized through an 80% reduction in manpower for needed maintenance.
Petrasek says HDR Engineering has researched pump technology to identify companies that manufacture concrete volute pumps. Out of a list of eight manufacturers worldwide, three were identified as companies with which HDR Engineering could partner in bidding for projects, including CLYDEUNION, which brings its technology from Scotland; Flowserve, which brings its technology from Holland, and the power division at Alstom, which derives its technology from France. “All three are multinational companies and, as near as we can tell, make a fine product,” he says.
CLYDEUNION’s concrete volute pump is used for water transfer and lift stations in such applications as water and industrial, conventional power, and nuclear power. It handles flows of up to 530,000 gallons per minute and heads of up to 230 feet. Flowserve’s BSV and BCV concrete volute pumps are a vertical, wet pit design used for large flow, continuous operation applications, and their designs reduce noise and vibration. Applications include circulating water, condenser cooling, dewatering, drainage, dry dock, flood protection, water supply, irrigation, stormwater, and water for such industries as water treatment, water supply and distribution, nuclear power, ground water development, and irrigation and flood control.
Flowserve’s BSV pump, with an open mixed-flow impeller, handles flows of 500,000 gallons per minute and has a head of up to 72 feet. The BCV pump, with a closed mixed impeller, has a capacity of 500,000 gallons per minute with a head of 105 feet. Other factors not relating to pumps, but acting as a driver is a trend toward the switch to high-voltage motors, notes Petrasek.
“People who used to be operating on 480 or 2,300 volts now are tending to switch to 4160,” he points out. “When you’re operating at a higher voltage, typically you end up with a lower rate from the power company, and since you’re operating on a higher voltage, typically your switchgear and motors are going to be used less, and you’re going to get a cost reduction.”
With respect to larger horsepower motors, Petrasek has noted a shift away from induction motors to a preference for synchronous motors.
“Additionally, we’re finding that there is a pretty significant increase in the use of variable frequency drives,” he says. “The price on those has come down, and a lot of our clients like the fact they have more control in their pump stations. ”
HDR Engineering also has an increasing number of clients considering putting some type of lining inside the pump casing to get an increase in pump efficiency of 1 to 1.5%, says Petrasek.
“That’s not huge, but over the life of the pump–if it’s a large horsepower pump–it could certainly pay for itself,” he says.
HDR Engineering also is seeing a “pretty significant increase” in the desire to be able to operate pump stations remotely, Petrasek says.
“That’s a good thing, but it’s also a bad thing,” he says. “If you go with remote operation, that generally means you’re going to have a more complex pump station because of the increase and the complexity of the instrumentation control required for remote operations. You’ve got to have a more capable staff to troubleshoot and maintain the instrumentation of the control system.”
A discussion that HDR Engineering has had internally quite a bit is how municipalities should be positioning themselves to address the challenges of keeping capable, high-tech staff members to operate higher levels of technology against the background of budgetary challenges, notes Petrasek, calling the situation a “double-edged sword.”
Another factor that is causing municipalities to sit up and take notice is whether its officials are prepared for the consequences of an unanticipated flooding event. And there’s a kind of Catch-22 involved in not having the budget funds to upgrade the pumping equipment if a system can’t handle unanticipated rain events, yet being forced to foot the bill for dealing with the aftermath of such a disaster.
“In Dallas, we need about a billion dollars in for interior drainage improvements,” says Petrasek. “We’ve got one bond program that’s taking care of some of that. We’ll do another bond program sometime in 2011.”
Using Dallas as a representative municipality of what many do or will face with respect to water issues, Petrasek speaks of how the Trinity River nearly dissects the city, with levees on both sides to keep the river from flooding the city.
“Where the pumps get involved is before they built the levees, rainfall used to run down and get into the river,” says Petrasek. “Now when a levee is constructed, rainwater can’t get to the river. What gets influenced is the interior drainage system within a city. All of that water that used to flow through the river and can’t get there because of the levees now has to be pumped out. The concern first off in a lot of places is the interior drainage systems were designed decades ago, and they probably need to be upgraded, and, in fact, that’s what the city of Dallas is currently doing.”
The interior drainage system is a separate problem–and a separate engineering and design issue–from the levee system and the levees being breached, says Petrasek.
“If you have enough water to breach a levee, you probably have enough water to overwhelm your interior drainage system,” he points out. “Generally speaking, levees would be designed–at least in our part of the country–for what’s referred to as a standard project flood, and, in Dallas, that’s roughly equivalent to an 800-year flood.”
If levees in Dallas get overtopped by the standard project flood, the city could see damages upward of $8 billion, as estimated by the US Army Corps of Engineers, says Petrasek. There’s not only the financial implications, but other major human impacts as well in the city, which is the eighth largest in the United States with a population of 1.3 million. “You want a very high degree of safety built into levee systems because of the consequences if the levees fail,” he notes.
Other projects include installing diversion pump stations on a river when it is at high flow to divert deep flood waters to an off-channel reservoir and store it there, and bring it into the system as needed for public supply, Petrasek adds. All of these approaches involve the use of “pretty-good-sized pumping units,” he says.
While Petrasek concedes that a system cannot be fixed “all at one time,” as long as a municipality has a program, the solutions will eventually be rolled out, and severe problems are, in most cases, “pretty rare events.”
“If you have a flood that has a probability of 0.01 occurring in a given year–which is what a 100-year is–it’s a low-risk thing,” he says. “That doesn’t mean you couldn’t get three 100-year events in a row, because that certainly has happened before. The whole issue is putting in good fiscal resource management on behalf of the public entities that are charged with providing that protection.”
In the meantime, the overall aging of the nation’s infrastructure is a “huge problem,” Petrasek points out.
“Water lines, sewer lines, and city streets–those three items out there are really big ticket items,” he says. “Failing to keep up with that issue is tantamount to an engineering company letting its computers get all outdated at the same time. All of a sudden you get a huge capital investment, and you say, “˜how much longer am I going to pay for this?’ Generally speaking, if you look at national budgets, you’ll see, in the US, transportation budgets seems to be four times the size of water and wastewater budgets, in terms of construction put-in-place.
“Transportation tops the list of where the big dollar problems are,” he adds. “If it takes a little longer to get to work, that’s inconvenient. But on the water side, if someone turns the tap on and they don’t get water–that’s a real problem.”
Communication with local officials and the public is key in addressing water efficiency issues, Petrasek says.
He explains that, years ago the Dallas city staff told the city council that Dallas had a problem with the water and piping system that needed to be fixed. The council directed the staff to put together a program to fix it.
“We know it’s not going to get done overnight,” says Petrasek. “Here we go through two or three design contracts and several construction contracts every year that are just water and wastewater line replacement jobs. We spend several million dollars a year doing it, and we’re making headway. We’ve got a bond program coming, and we’ll let one of the programs be the interior drainage system and let the voters vote on it. The last vote passed overwhelmingly, no problem.”
Petrasek tells the story of how one of Dallas’ former mayors was speaking at a luncheon some time ago and commented about how to handle public relations with residents. Now serving as President Barack Obama’s US Trade Representative, Ron Kirk reportedly turned to a political advisor who told him, “You know, the truth is always an option.”
“When it comes to working with the public, just laying out the hard facts and what’s needed to be done to fix the problem usually gets you where you want to go,” says Petrasek. “But you may have to deliver the message pretty carefully.”