In 1791, Thomas Jefferson wrote, "Lake George is without comparison the most beautiful water I ever saw. Its water is limpid as crystal and the mountainsides are covered with rich groves of fir, pine, aspen, and birch down to the waters edge". Jefferson is not alone in his account of Lake George - it has been recognized the world over for its crystal clear waters and pristine beauty. It is this beautiful setting that has made the lake in the Adirondack Mountains of New York State a popular vacation destination.
But with the hordes of summer vacation tourists comes increased water use and a requirement for a wastewater treatment infrastructure that can handle the ebb and flow of the area's seasonal population. With effluent coming from hotels, shopping malls and residential sources, the Town of Lake George has two municipal sewage lift stations – one serving upper Lake George and the other serving lower Lake George, which pump effluent to a central treatment facility.
Approximately 15 years ago, the upper sewage lift station had incorporated into its design two 150 hp and one 60 hp long shaft pumps. The shafts were almost two stories in length. The lower pump station was designed with a total of three long shaft 75 hp pump units. At the time, the primary concern was the ability to handle the high seasonal sewage flows from the many summer guests who crowded events including music and theater festivals and even a large motorcycle rally. Unfortunately, the pumps were not properly sized. Keeping the pump stations operating cost effectively proved to be difficult. Everything from the extra supports on the shaft to help eliminate vibration, to replacing pump components such as impellers and mechanical seals, created an unending maintenance nightmare for the Town of Lake George.
New Pumps
A routine sales call by Brian Marshall, a sales engineer for the ITT distributor Emerick Associates in Cohoes, NY, provided a path for the town to fix its lift station problems.
"I stopped in at the Lake George town garage to meet with Dan Merino, the Town supervisor for the pump stations," Marshall recalled. "As we began our meeting, Merino said, "OK, if you know so much about pumps, then take a ride with me and tell me what is wrong with our pump stations."
"We drove to the upper pump station and we went about three stories underground to view the pump installation. By examining the upper pump station with Merino, it was evident the existing pump units were oversized. The long shaft arrangement had excessive vibration which would shake the parking lot and surrounding homes," Marshall said.
Reviewing the pump arrangement, Marshall also learned that the discharge valves had to be closed approximately 90% so that the pumps could operate adequately.
Reviewing the application with Merino, it was evident that the existing maintenance problems and high energy costs could be eliminated with the incorporation of ITT Flygt brand dry pit pump units controlled with the ITT PumpSmart® controller.
In an effort to drive down the extremely high maintenance and energy costs of the existing lift stations, it was agreed to test one 70 hp Flygt Model 3202 pump in the upper station. At the heart of the pump is the proven N-impeller, a unique, self-cleaning semi-open impeller design that reduces the risk of clogging and maintains high pumping efficiency. The new pumps also include an improved cooling jacket, which extends component life.
Although specified for use in a dry-pit application, the Flygt pump is also submersible. If the sewage lift station was flooded, the pumps would continue to operate.
Pump Control
In an attempt to address the seasonal changes in pumping demand, it was also agreed to install the Flygt pump with the PumpSmart v5.0 control system as a way to handle the different volumes of flow and provide pump protection. PumpSmart is ITT's award winning intelligent flow system that works with any pump. It uses a "smart" VFD controller and proprietary control software to provide advanced process control that can increase reliability, reduce life cycle costs and significantly lower energy costs - up to 65%.
Unlike standard drives that must be designed for a wide array of equipment, PumpSmart was designed for pumps and as a result the set up is very simple and intuitive. With Smart Flow™ - or sensorless flow measurement – the control system is able to programmatically derive the specific speed design of a pump and can accurately define the pump flow rate by leveraging torque and speed.
PumpSmart knows exactly where a pump is operating on the performance curve and will protect it from dry running, low flow recirculation and run out cavitation conditions - all of which are detrimental to pump performance.
With each pump application having unique challenges, the PumpSmart controller has artificial intelligence pump and process logic including 40 different pump process features that were designed and embedded into the control logic to address a wide array of pump specific problems.
Successful Test Leads to Retrofit and Cost Savings
After a successful testing period with one Flygt pump, the two sewage lift stations were each specified for three Flygt 3202 70 hp pumps, each controlled by a PumpSmart PS 200. If one pump cannot keep up with the flow, a second pump kicks in. And if one pump went into a failure mode, the third pump would begin operation. However, Marshall notes that since the ITT pumps and controllers were installed, there has never been a situation where more than one pump has needed to run.
From an improved maintenance perspective, "these pumps have been in service for over two years and we have not touched them," Marshall said.
The energy savings for the town have also been dramatic. The PumpSmart controller readout indicated that the ITT pump is actually only using 43% of the total motor load. This in itself is saving approximately 100 horsepower when compared to the 150 horsepower pumps they replaced in the upper pump station. These two factors result in a saving of approximately $30,000 a year in energy alone.
