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Pumping Stations

KATIE NAVARRO | Irrigation

When we think of a pump station, we’re usually thinking of water purveyors who are pumping water so your home can have potable water for drinking, showering, etc. Golf enthusiasts might see pumping stations as a way to pump water from one pond to another.

But few of us realize that pump stations are used in a commercial environment as well. If you’re in the commercial arena and are not familiar with pump stations, I would suggest that you take a closer look. You may be leaving money on the table.

What is a pumping station? “A pump (or pumping) station is prefabricated. It shows up with a pump, a motor, the control panel and a valve assembly,” explained Jeff Bowman, project engineer for Irrigation Consulting Inc. in Pepperell, Massachusetts. Using the various components, they are assembled in a factory to exact specifications, and then shipped to the site. Some are even enclosed in a steel container. Sometimes referred to as a pump in a box, a pump station is a complete package. It is used to boost the operating pressure and gallons per minute output on commercial-sized irrigation projects.

Contractors who encounter a pump station specified on a commercial or municipal project should “recognize that this is a custom solution approach that is tailored to each application, location and water source,” Keith Kuehn, manager of corporate marketing for Rain Bird Corporation noted. “Pump stations are complex and require attention to detail to be an effective and efficient solution.” It can provide energy and water savings, but requires a high level of attention to detail. A pump station plays a more significant role than simply providing water at a given point. “It’s not only about where the water is needed, but how much water is needed, in what form (rotors, sprays, etc.) and in what time frame,” Kuehn explained.

There are four different types of pumps that can be used to boost an operating system. They include a water-proof submersible, turbine, vertical turbine and centrifugal pumps. Pump selection is always based on the site and the output needed. “The most common pumps in the irrigation industry are the centrifugal pumps,” said John Heidman, consultant with IrriTech Corporation in Dallas, Texas. “They can be as small as a loaf of bread or as large as the size of a small keg of beer.”

As with the design of any irrigation system, there are several site-specific factors that must be considered before determining how to build the best station for the customer. Water supply is one of the first pieces of information needed. “Is the water supply from surface water or holding tanks? Or is the water supply domestic water, from a street main?” Bowman asks. What is the available pressure for the irrigation system? In most situations where domestic water sources are available, there is enough static or residual pressure on the system to effectively operate an irrigation system.

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Within the last three years, the irrigation industry has experienced significant changes because water conservation has become an important aspect of the irrigation industry. “Certain municipalities are disallowing the use of public water mains for irrigation systems,” Bowman explained. “When a system is designed, the water must come from stored water first, wells second and municipal water as the last option available.” Non-domestic water sources will usually require a pump to boost gpm and psi, especially in situations where water is pulled out of a low spot and pushed up an incline.

Confirming the water source before finalizing an order for the pump station is imperative. On some commercial projects, an irrigation design is completed long before the water source is available. The well may not be dug or the municipal water lines not yet installed. Specifications for the gallons per minute and psi are then based on a projection—that is the ideal situation.

If those specifications do not materialize once the water source is installed, the pump station will never function properly. “My advice for any contractor is to start with the water supply and go out from there,” Bowman cautioned. “Do not install an irrigation system until the water source is secure.” As basic as that sounds, entire systems have been designed and spec’d out according to a water source that never materialized when it came time for installation.

Early identification of the water source is crucial for performance, but also for understanding if and what type of filtration unit is necessary. “When the water source is finally identified, what type of water it is and if it needs filtration have to be determined,” said Adamson.

Does it need treatment for bacteria or algae? What is the pH content and are there any suspended solids? Adamson emphasized, “Knowing what, if any, treatment to the water is critical to the performance of the system.” Rotors, sprays and drip products can become clogged if a filtration unit is not added to the system. Designers will often require a filtration device and in some cases even specify a particular manufacturer.

The available power supply is equally important as the water supply. What type of power is available on site? Is it single phase or three phase? When a pump station is specified, it is designed to operate with singe phase (110/220v) or three phase (240/480v) power and cannot be interchanged. Verification is essential.

Once the operating requirements and site conditions have been confirmed, preparations must be made for the installation. Typically, a concrete pad 2" thick and 2" longer than the unit on each end is poured for the pump station to sit on. Provisions should be made for any piping or electrical conduit that is needed. In some situations, the inlet or outlet pipe and the electrical conduit should be run up through the concrete pad, explained Nick Shebert, irrigation technical services manager of Turf- Pro in Sacramento, California.

Two critical components of a pump station are an intake pipe and a discharge pipe to move water through the system. “I always use and recommend metal pipe,” said Heidman, said. “PVC pipe is rated at 73 degrees and the heat of the water flowing through the pump can cause the pipe to balloon. I prefer copper pipe, but galvanized pipe is okay.” He added that it is essential to oversize the intake and discharge lines. “On the suction side, be generous. If you have 2" on the pump, go up to 2? or 3" on the pipe,” said Heidman. “On the discharge side use 1" up to 2" or 2+".” In many cases, a pump station will be specified into the original architect’s design.

Determining where the pump will stay onsite is another important consideration in the early stages of design. “The pump arrives in an enclosure, but where are you going to put it?” Bowman said. “Some sites have size constraints.” The unit can be left out in the weather or put in a basement or maintenance shed. Site conditions, whether local or regional, weigh heavily in the design stages of a pump station. Incorporating a pump station on any site requires a close partnering between the contractor and manufacturer to ensure that the pump is the right type and size for the task at hand. “Contractors can save themselves a lot of time and problems if they specify the correct physical configuration from the beginning,” commented Shebert.

“Manufacturers don’t just drop a pump station off and leave,” said Bowman. Authorized service technicians visit the job to complete a certified start-up and check the pressure, water flow and shut-down functions. Because small pumping stations are needed on commercial sites such as new retail locations or athletic fields, the project can be complicated, especially if it is a union job. Certified service technicians must be on-site to ensure proper installation and start-up, but union workers must be present to help turn wrenches, explained Bowman.

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“A close partnership provides a greater depth of technical support,” Adamson said. It is critical during design, installation and throughout the life of the station. “The last thing any customer wants is to install the pump and have it become problematic. It will put a drain on profitability and the structure of the business model. In the end, the customer will be unhappy.”

In addition to manufacturer-specific warranties, extended service agreements can include telephone support and preventative maintenance once or twice a year. “A pump station is like a car. You take it in to have the oil and air filter changed,” Kuehn explained. “A pump needs a change of oil and a tune-up. It will save energy costs, and efficiently use water to eliminate overspray.”

“A pump is only going to do a certain amount of work,” Heidman cautioned. “It is better to design for the worst-case scenario.” Inaccurately sizing the pump can create two problems. If undersized, the pump will never be able to create the gallons per minute, or pressure per square inch, needed to successfully operate the system. On the other hand, if the pump is oversized it will cause cavitation. “Cavitation is when the pump pulls the water so hard, it will pull the air out of the water,” Heidman explained. “It can be heard hitting the impeller and sound like bb’s hitting, and will erode the impellers.”

“Working with pump stations opens amazing opportunities for the contractor who can step out and see the real benefits of a pump station to their area and their customers,” Kuehn said. The clientele interested in using pump stations for their projects will understand the overall value and costs savings versus the initial installation and start-up expenses.

 
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