Above and Beyond

Water plant upgrades help Rockville, Md., conserve energy, improve production, and win a leadership award from the U.S. EPA
Above and Beyond
Eric Welninski, water plant operator, tests a water sample at the Rockville treatment plant.

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Producing a reliable supply of clean, safe water was not enough for the City of Rockville (Md.) Water Treatment Plant. The city wanted to make its water system operations more energy efficient and more sustainable.

To that end, in fall 2009, the city combined $1.7 million in federal stimulus money from the American Recovery and Reinvestment Act (ARRA) with $2 million of its own investment to complete a 19-month plant upgrade project.

Even before the ARRA was enacted in February 2009, the city was looking into capital investments to update the water treatment plant. Put into service in 1958 with a capacity of 4 mgd, the plant was upgraded in 1967 to increase production to 8 mgd and upgraded again in the mid-1990s to meet federal and state regulations.

Since then it has produced an average of 5 mgd. Water from the Potomac River goes through a six-step treatment process built around dual-media (sand and anthracite) filtration.

 

Many facets

The multi-phased upgrade project involved extensive planning and coordination to ensure that work on the aging plant was completed quickly and without disrupting service to the city’s 46,000 water customers. The project, which ultimately earned national recognition, involved multiple improvements.

Workers rebuilt two Fairbanks Morse raw water intake pumps to improve production efficiency and cut energy usage.

Allen-Bradley (Rockwell Automation) variable-frequency drives (VFDs) were installed on two raw water pumps, enabling incremental speed control so that the pumps work only as hard as needed to match demand, saving energy and related cost. Previously, only one intake pump had a VFD, so it was more difficult to achieve the desired flow.

For cooling in the pump house, an inefficient 16-year-old air conditioning unit that used river water in the heat exchanger was replaced with a new high-efficiency air conditioner (United CoolAir Corp.) that uses refrigerant. New thickened-solids pumps (Moyno) were installed with Allen-Bradley VFDs to feed the solids press more energy-efficiently.

New polymer and press feed pumps (Moyno) and Allen-Bradley VFDs were installed to replace 15-year-old pumps. The new pumps save energy by allowing technicians to coordinate the polymer and sludge feed rates to the press. In addition, 20 plates were added to the solids press to increase production by 40 percent per run cycle. The additional plates are particularly helpful during storm events because mud (silt) removed from the raw water can be treated more quickly without backing up the system.

Thirty-four Hubbell motion sensors were added to save energy on lighting and extend lamp life. Now lights turn off automatically in areas where operators are not working.

To help measure and manage power consumption, Eaton power monitors were installed at the intake station, and Basler Electric power monitors were installed at the treatment plant. Data from the monitors will help the plant staff track power usage and identify areas to improve efficiency in the future.

 

Funding boost

For Rockville, the ARRA funding came at just the right time. Once the federal money was made available, treatment plant superintendent Vernon Simmons and the Public Works Engineering Division sprang into action and submitted the plant’s needs to the Maryland Department of the Environment for grant consideration. Approval took only six months, and Rockville proceeded with upgrades immediately. Construction began in December 2009.

Grant funds helped shorten the project cycle. “Without the ARRA funding, we wouldn’t have been able to complete all the upgrades we needed in such a short timeframe,” says Simmons. “It would have taken more than five years to complete everything.

“Thanks to the grant and cooperation from the city council and citizens of Rockville to provide additional funding, we completed everything in less than two years. And not only did we get done all the projects we wanted to accomplish, but we now have additional energy efficiencies because of the ARRA funding. It has been a win-win situation.”

Ultimately, more work got done for the investment because pairing the city’s money with the ARRA grant allowed Rockville to pay for one larger project instead of several smaller projects, so that the contractor was mobilized just once instead of multiple times.

 

Smooth transition

To keep the upgrade moving smoothly and on schedule, contractors started work on the most time-consuming update first: the rebuild of the raw water pumps. Then smaller projects were added throughout the larger initiative’s duration.

The plant’s equipment redundancy was important to ensuring full production capacity during construction. In the case of the raw water pumps, while one pump was being rebuilt, two pumps remained online and performing at the necessary levels. When a rebuilt pump came back into service, the next pump could be rebuilt.

“Construction is always easier when it’s a brand-new site and you don’t have to continue existing operations to produce and deliver potable water,” says Judy Ding, deputy director of utilities. “But we have an obligation to continue service without disruption to our customers. While these installations were happening, we continued to operate at full capacity.”

 

Communication is key

The city hired CPP Construction of Gaithersburg, Md., as the prime contractor. Environmental engineers at Hazen and Sawyer developed the plan, design and specifications and conducted inspections during construction, as did engineers with the city’s contract management group. With so many parties involved, it was necessary to keep everyone updated regularly.

“For a project this size, it was important for the whole team — the contractor, subcontractors, engineers, construction inspectors, management and plant staff — to coordinate,” Ding says. “To succeed at this kind of coordination, communication was of utmost importance.”

To keep all groups in the loop, Simmons sent everyone regular update emails. Representatives from all parties attended construction progress meetings twice monthly. CPP Construction kept a schedule and provided two-week outlook reports, adjusted weekly. As coordinator of the entire program, Simmons walked the plant frequently to make his own observations, helping him foresee potential problems that would require logistical adjustments or further group coordination.

 

National recognition

In June 2011, the U.S. EPA presented the city with a Sustainable Public Health Protection Award for the water plant upgrade. The award recognizes innovative leadership in financing, planning, implementation, partnering, and promoting sustainable infrastructure.

While Simmons and Ding are pleased that the project has been publicly recognized, their ultimate objective was to protect the public health and be good stewards of public dollars. “We want to ensure that the plant provides sustainable drinking water for generations to come,” Ding says. “The community recognizes that, through this project, we have demonstrated our commitment to providing high-quality drinking water to our customers.”



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