One of a kind

A major upgrade that included a rapid clarification process new to Ohio allowed Steubenville plant operators to prove their mettle.
One of a kind

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When the City of Steubenville's new water treatment plant started up in August 2007, the operators were challenged with learning new technologies and transitioning from manual to SCADA operation.

"Learning the new SCADA system was the biggest challenge," recalls water department assistant superintendent Bill Skinner. "Before, they would manually open valves to increase flow or obtain the right chemical settings."

A series of power outages within days of plant startup didn't help. "They were put into a situation where they had to learn under duress," says Skinner.

Designed to meet future turbidity and disinfection byproduct rules (DBPR), the plant includes high-rate single-basin flocculation/clarification technology, low-lift reservoir and backwash pump stations, an administration/laboratory/chemical building, and an electrical building.

The plant team chose the new clarifier system after a pilot study in 2001-02 that allowed designers to set optimum chemistry parameters, coagulation, and filter media performance at various flow rates and source water turbidities for fall and winter.

A combination of classroom and hands-on training, operator experience and initiative spelled success. The plant hosted the 2008 AWWA Northeast Ohio District summer meeting and tour. The facility earned the 2008 Design-Build Institute of America Ohio Valley Region Design-Build Award for engineering firm MWH Global.

Outdated plant

Founded in 1810, the Steubenville Water Department serves the city and parts of northern Jefferson County. Water is pumped from the Ohio River at the Alikanna Pump Station to a 6-million-gallon reservoir at the filtration plant.

The city's first plant, built in 1915, consisted of a baffle-type gravity mixing chamber, two underground coagulation basins, six mechanical gravity filters, a clearwell, a wash water tank, three chemical orifice tanks, flowmeters, rate controllers, hydraulic valves, two wash water pumps, an air compressor and two chlorinators.

The facility was upgraded in 1955 and 1963-65, and a new finished water pump station was built in 1970, providing one active pump and two spares. In 2001, the city built a new raw water pump station, with three pumps, a potassium permanganate feed system, and SCADA system.

Although the 92-year-old-plant was still meeting quality requirements, it would not have been able to meet upcoming turbidity and DBP regulations. "The river water has turbidities from 4 NTU to over 80 NTU," says Skinner. "Yesterday, the turbidity was 7; today it's 21. If there is a rainstorm anywhere from western New York to Morgantown, W.Va., it affects the quality of our source water. Our plant is a national weather recording station, so we pay close attention to the weather."

The old system also posed operating challenges. "The old lime softening plant had no computer operation," says Skinner. "The two elevated distribution systems' tank levels operated off the pressure gauges at the plant, and operators would manually start and stop the pumps based on those gauges."

Superpulsator technology

In 2000 the city hired MWH Global to design and build a new 6.0 mgd water filtration plant on existing city land next to the old site. Lacking storage capacity to shut down and drain the clearwell, MWH constructed a temporary 26-foot steel wall to isolate the two sides of the tank. Workers drained one side of the clearwell and built the permanent wall while the other side stayed online.

Since space was limited, MWH recommended Superpulsator technology (Infilco Degremont), which combines flocculation and coagulation in a single tank. There is no need for additional sludge collection and removal facilities, and there are few moving parts. The existing settling tanks were converted to a residual holding tank, and the existing backwash wastewater holding tank was converted to the backwash water tank.

The Superpulsator unit is an upflow system that combines sludge-blanket flocculation with inclined plate settling. Chemically dosed raw water enters a high-rate flocculation tank, then flows by gravity to a sealed vacuum chamber that discharges the water to laterals at the bottom of the reactor. A pump creates a vacuum in the chamber, causing the water level to rise to a predetermined height.

A timer actuates an inlet valve on the chamber to open quickly so that the water stored in the chamber drains rapidly into the bottom of the distribution system. This discharge creates a pulsating action, while the sludge blanket expands in the reactor.

As the water moves upward in the reactor, it starts to flocculate. A system of parallel plates inclined at 60 degrees enhances clarification. The upper level of the sludge blanket is controlled by overflow into a sludge concentrator, where the excess sludge is thickened before discharge. Above the inclined plates, the clarified water is collected through a set of submerged laterals.

To the test

The operators and laboratory technician were involved with the Superpulsator system pilot study and performed tests on incoming and finished water samples with laboratory analysts from Infilco Degremont. Says Skinner, "Because the operators learned quickly, this was the first location for an Infilco pilot study that successfully used and educated plant personnel in operating a pilot plant without the need for constant on-site Infilco staff." Besides the Superpulsator system, plant equipment includes:

Ferric chloride, caustic soda, fluoride and orthophosphate chemical feed pumps (Watson-Marlow)PolyBlend chemical feed pumps (Siemens Water Technologies)Liquid chemical transfer pumps (Iwaki - Walchem)Chlorine feed system (Siemens Water Technologies)Powdered activated carbon dry chemical feed (MERRICK Industries)In-line InstoMixers (Walker Process Equipment)Lightnin Rapid Mixers (SPX Flow Technology)Dual-media filters and filter underdrain system (Leopold – a Xylem Brand)Electric operating valves and rate-of-flow control valves (Rotork)PLC SCADA system (Allen-Bradley/Rockwell Automation)Computer-controlled plant operating system (Rockwell Automation)Flowmeters (Yokogawa)Continuous pH, chlorine, fluoride and turbidity meters (Hach)

Transition challenges

At the startup of the new plant, some operators were excited, while others were intimidated by the computer-controlled technology, Skinner recalls. The old lime softening plant used computer entries only for state reports and records; every operation was a hands-on control system. Operators walked from room to room and building to building to operate the plant and maintain levels in four water distribution systems.

With the new system, operators were worried that a wrong click of the computer mouse would hurt water quality or create an overflow somewhere. One plant operator never owned a computer and had to learn all the basics before operating the new plant.

"It was very difficult for this operator to download all this new information at once," recalls Skinner. "The staff pitched in a little extra every day to work with him. He got up to speed with reassurance that the rest of the staff would help out when needed."

Four to six weeks before startup, equipment vendors conducted classroom and hands-on training for the chemical pumps, powdered activated carbon, flow valves and controllers. They covered flow rate adjustment and chemical mixture preparation.

"Two weeks of vendor training on the SCADA system helped transition the operators over to computer command and live continuous data feedback," says Skinner. "Training also included identifying and applying the individual PLC module components." Operators relied heavily on the O&M manual.

"It was easier to read the instructions step -by-step and mouse-click-by-mouse-click simultaneously for some tasks, just as someone would do for installing computer software on a home computer, until the task became routine," says Skinner.

The transition would have been easier if not for the power outages that started three days after the plant went online. The outages resulted from wind damage, power substation failures, a residential house fire and a downed telephone pole. There were seven outages in the first five weeks of operation, the longest lasting 13 hours.

Fortunately, the plant had an emergency generator as mandated by the Ohio EPA. "The plant influent pumps, electric filter control valves and chemical metering pumps can run on generator power, but in manual mode," says Skinner. "So, the operators have to go out and tie them into the SCADA flow pace mode again and check to make sure they are running properly."

Showing initiative

Skinner is fortunate to have self-motivated employees. Assistant operator George Kovach modified the clarified water collection laterals so that they are self cleaning. Previously, the laterals were cleaned with a pool brush on an extension pole. The brush was flat and the surface of the collection lateral is round.

Kovach took a small link chain and mounted it between the tips of an old Y-shaped pool skimming net brace after removing the tattered net. Now, the chain molds to the rounded shape of the collection lateral as it glides across the surface and gently pushes away any floc.

Operators designed a device to clean the Superpulsator vacuum chamber's vertical water level indicator sight tube. The clarifier water rises in the 1.5-inch-diameter clear tube equal to the water level in the vacuum chamber.

"It's important to view the water rising and falling in the tube from the pulsing action," says Skinner. "The tube is glued into position, since it must remain airtight to operate properly, so it's very difficult to clean."

Skinner and chief operator Rocky Zinno soldered a torpedo tip on one end of a U-shaped 0.5-inch copper pipe and a garden hose adaptor on the other end. Operator John Gentile soldered a two-inch-diameter laboratory bottle brush onto the tip of the torpedo end and drilled eight staggered small holes below the tip of the torpedo to provide water scouring as the brush slides up and down inside the tube.

Better quality

With diligent maintenance and the improved technology, the new plant has enhanced finished water quality:

45 percent total organic carbon (TOC) removal in 2011, versus 20.7 percent in 2006.Clarified water turbidity to the filters at 0.091 to 0.235 NTU in 2011, versus 0.800 to 1.670 NTU in 2006.Combined filter turbidity at 0.023 to 0.067 NTU in 2011, versus 0.160 to 0.270 NTU in 2006.

Trihalomethane (THM) levels in 2011 were less than half the 2006 levels, as the Superpulsator system coagulant (ferric chloride) significantly reduced TOC. Lowering the pH in the distribution systems by using orthophosphate instead of lime coating for corrosion control also helped reduce THM.

The new plant's peristaltic chemical pumps are more accurate and reliable than the old high-maintenance volumetric and gravimetric dry chemical feeders. And, the Superpulsator clarifiers "operate themselves," says Skinner. "The Allen-Bradley controller adjusts the vent valve timing to control the volume and timing of the pulsing, and it also controls excess sludge removal. There are reliable vacuum pumps that run 24 hours a day to supply the lift in the vacuum chamber."

Easier on operators

New technology has made operators' lives easier. "With the old plant, they had to manually adjust the chemical volume on every chemical feeder every time the water flow through the plant changed," says Skinner. "With the SCADA, the flow pace automatically adjusts every chemical feed throughout the plant."

"The coagulant we use is 41 percent ferric chloride, but because we receive it in liquid form, a certain delivery might be 41.7 or 40.7. We can enter the exact figure in the SCADA, and this helps control the chemical application."

Operators have become accustomed to the sights, smells and sounds of the new equipment. "They use their ears as much as the eyes or nose, since we have noises we didn't have before," says Skinner. "We have an air-operated valve with a compressor and vacuum pumps that run all the time, so you get used to hearing the vacuum chamber release and the swish of air. You still have to use your senses and not just look at a computer screen all day."

This came in handy recently when operators heard air leaking from an air-operated solenoid valve that needed to be replaced. Occasionally, the polymer diaphragm pumps experience reduced audible stroke knocking. Operators must take the pump apart, extract the hardened compressed polymer from the chamber, and check the balls, springs and effluent line before re-assembling the pump and placing it back into service.

Operator Michael Boone found a very small chlorine leak caused by a nearly invisible crack in the combined filter effluent chlorine line in an outdoor vault. "The efficient operation of any water plant requires the operators to have good sensory perception," says Skinner.

Always improving

The operators better themselves by advancing to the next license grade. "They're constantly learning and looking at new ways of doing things and finding better methods for running the plant," says Skinner.

They have completed the basic water and advanced water courses offered by the Operator Training Committee of Ohio (OTCO). They also take the Sacramento State University operator training correspondence courses on different water treatment topics. "This is much more effective than seminars, since they are exposed to so much more information," says Skinner.

In April 2008, eight months after startup, the plant team conducted a full-scale study with the Superpulsator clarifier and a filter to see if they could high-rate the system. "This was successful, and we were upgraded to a 7.5 mgd plant with a 6.0 mgd operating capacity, without having to build another Superpulsator or filter," says Skinner.

In 2010, the plant upgraded to a second communication system, along with a new river pump station and transmission lines and four new distribution tanks. "Right now, we're considering another full-scale Superpulsator study to see if we can push our current plant production even higher to accommodate more water customers," says Skinner. "If not, we have room to add an additional Superpulsator unit to meet future demand."

With the current economy and limited infrastructure funding, that remains to be seen. "We're experiencing the funding squeeze every water system currently feels to operate and maintain their systems," says Skinner.

Nevertheless, the plant is solidly on course for a long life producing high-quality water for Steubenville and its surroundings.



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