Tackling Turbidity

An experienced and highly qualified team and a newly upgraded treatment plant keep quality water flowing in Clifton Forge, Va.
Tackling Turbidity
John W. Riley Jr. backwashes a filter at the Clifton Forge Plant. Riley was the 2010 Virginia Operator of the Year.

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The Clifton Forge Water Treatment Plant is one of very few surface water facilities with no population, industry or agriculture upstream from its intakes on spring-fed Smith Creek. Originating in the heart of George Washington National Forest in Virginia, the cold, pristine water is the plant’s biggest challenge.

When the plant opened in 1960, operators thought they were doing something wrong because the water wouldn’t flocculate properly until they replaced the standard ground alum with activated alum. “Cold raw water and low turbidity combined to make floc formation extremely difficult in winter,” says Bobby Irvine, plant manager. “Even in summer, water temperatures hover between 54 and 57 degrees F.”

The plant was not designed with turbidity as a top priority, and water conditions deteriorate in direct proportion to rainfall and snowmelt. “Our greatest accomplishment was producing quality water with outdated equipment in an aging facility,” says Irvine. “We kept things going when there was little money to buy what we needed.” The plant has never lost a day of service since Irvine became plant manager in 1986.

The long overdue upgrade arrived in 2008, but not before the Virginia Rural Water Association named Clifton Forge the 1999 State Water System of the Year. The association named Irvine the 1998 State Operator of the Year. John Riley, assistant plant manager, earned the 2010 State Operator of the Year award, and Tony Kimberlin won 2011 State Technician of the Year, also from the VRWA.

Clifton Forge also received the 2011 Excellence in Water Treatment award from the Virginia Department of Health Office of Drinking Water Waterworks Recognition Committee. The Southeast Rural Community Assistance Project presented the plant with the 2011 and 2012 Turbidity Removal Award.

First line of defense

Turbidity has been a battlefront for the plant as regulations have become steadily stricter. Raw water turbidity averages 0.9 to 1.1 NTU in dry weather, 2.0 to 4.0 NTU in wet weather, and more than 200 NTU on rare occasions, such as after hurricanes.

The $2 million renovation in 2008 included installation of a streaming current monitor (HF scientific) in the raw water line and a flash mix basin between the coagulant injection point and the rapid mix basins to optimize floc formation. Tube settlers (Meurer Research) were added in the settling basins to enhance turbidity removal, and the four rapid sand filters were upgraded to dual-media filters using anthracite (Roberts Filters).

“The original filters had hydraulic valves,” says Irvine. “After 50-some years, they were mean. Operators had to tap them with hammers to open and shut them. One of the happiest days of my life was when we installed the electronic valve actuators [AUMA Actuators].”

Today, the plant draws water via screened intakes on one of two inline dammed reservoirs, delivering 1.3 mgd through 35 miles of mains to more than 8,000 customers in Alleghany, Botetourt and Bath Counties.

A daily average of 15 gallons of DelPAC 2020 polyaluminum chloride (PACl) solution (USALCO) and 10 pounds of sodium bicarbonate are added to the raw water. When turbidity is high, operators use a Praestol N 3100 polymer feed system (Ashland). The mixed water then flows to two 45,900-gallon flocculation basins, each with rapid mixers.

Leaving the flocculators, the water enters two 269,000-gallon settling basins before flowing to the media filters. From the filters, water passes to a 126,500-gallon clearwell, where it is finished with 6 pounds per day of chlorine gas and 25 pounds per day of fluoride. Finished water is stored in four above-ground tanks and one elevated tank totaling 1.5 million gallons capacity.

“Recently, we retrofitted the flocculators with automatic frequency controllers and began using a coagulant charge analyzer [CHEMTRAC] as an aide to jar testing,” says Irvine. “These steps made life much easier for operators during major storms.”

By any other name

The plant operates 16 hours per day — the time it takes to fill the clearwell — then shuts down for lack of sufficient storage. “Adequate storage is near the top of my wish list,” says Irvine. “With it, we could shut the intakes when the creek is a muddy torrent, let it flow past, and lick most turbidity problems. We’re strapped by so many bothersome regulations, yet we don’t have one that mandates storage capacity based on population.”

In the 1950s at the height of the railroad influence in Clifton Forge, the city’s population averaged 6,800. Residents used all the water they wanted for a flat rate of less than $20 per month, which also covered sewer service and trash collection. January and February were the plant’s busiest months, as people opened their spigots at night instead of insulating their pipes to prevent freeze-ups.

Then the railroad left and half the residents went with it, leaving high unemployment and an aging population. By 2000, officials wanted to change the city’s status to that of a town to receive beneficial tax rates and perks unavailable to cities. When the referendum passed a year later, voters were promised that their water would never be metered.

As the plant upgrade loomed, officials discovered that becoming a town did not guarantee substantial grant money. The only way to get it was to meter the water — an unpopular prospect. After the town installed automatic-read brass water meters (Hersey Water Meter), monthly utility rates increased in July 2011.

“Two things happened,” says Irvine. “First, water usage dropped substantially. Second, the grant money went away and hasn’t come back entirely.”

Little gold mine

What has remained steadfast and propelled the plant to repeated award status is employee continuity. Irvine is only the second superintendent in the facility’s 53-year history. The team has a combined 83 years of experience. Irvine has been with the town for 41 years, and assistant Riley for 24 years. The newest operators are Kimberlin (seven years), E.R. Gilbert (five years), and Wayne Walton and Jeff Johnson (three years). Walton and Johnson are Class 3 operators; the others are Class 1 (most advanced).

“Any of them could do my job,” says Irvine. “The fact that a town of less than 4,000 people can boast four Class I operators in a small Class II plant epitomizes our long-term investment in quality drinking water.”

That commitment began when the community realized it had a unique asset and built the water plant, scheduled to open New Year’s Day 1960. “The excitement was palpable as everyone watched their spigots for those first drops of water — and nothing happened,” says Irvine. “The system was air locked. Operators went up and down the raw water line installing air blowoffs, and that’s why the plant opened a day late.”

From that day forward, the town council encouraged plant team members to involve and improve themselves. The town pays all expenses for training and licensing, including gasoline, lodging, meals and the operators’ salaries while they are in class.

“Today, our biggest challenges are the economy and increasing regulations,” says Irvine. “My prayer is that the community continues to recognize that quality potable water is its greatest asset.

This little water plant produces a product that will always be in demand, but we need their continued support to make it happen.”

Distant thunder

Next in line for financial support are the reservoirs. The primary (upper) reservoir has the best water, but small capacity — it is about 100 yards across at the widest point. Dredging it takes two or three days, during which time the plant draws water from an intake upstream in a coffer dam.

The secondary intake is in the larger (lower) reservoir, about 250 yards across at the widest. “No one knows what the capacities are,” says Irvine. “Because of that, the engineers don’t know how much capacity we’ve lost. Back in the 1970s, we pulled from the lower reservoir year-round. Now, its capacity is an issue.”

As sediment built up, algae proliferated in the shallower water. “Customers objected to the musty taste algae imparted to the water, and our phone rang off the hook,” says Irvine. The solution was switching to the upper reservoir by mid- to late-June before the algae bloomed, but that subjected the plant to higher turbidity, arriving more rapidly because the lower reservoir wasn’t there to act as a clarifier.

“We have a four-and-a-half-hour detention time between when muddy water roars into the intake and when it reaches the filters,” says Irvine. “That’s sufficient treatment time with the polymers and PAC, which have been a godsend.”

Dredging of the lower reservoir, last cleaned in the late 1960s, is in the planning stages and will be a major undertaking. Besides the expense of dredging, it will be a challenge to obtain permits from the state departments of Forestry, Game and Inland Fisheries, and Environmental Quality, and the U.S. Army Corps of Engineers.

Perfect storm

Floodwaters from three hurricanes were the largest contributors to the silt buildup in the lower reservoir, but a storm in early November 1984 was the water plant’s severest test. The storm delivered 6 inches of rain in eight hours before swinging around and repeating the performance. Irvine, then an operator, left home for work on Tuesday afternoon and didn’t return until Saturday.

“It was nip and tuck the whole time,” he says. “A small chunk of wood had wedged itself in the raw water valve and we couldn’t shut it completely. The mud eventually overwhelmed us and we had to shut down for three days. The state health department was here nonstop, and workers from the Westvaco paper mill in neighboring Covington provided help and equipment. It was a bad situation that could have been avoided if we’d had sufficient storage capacity.”

The dynamics of a community-owned water plant generate far-reaching ripples. School kids remember Irvine from their plant tours and greet him on the streets. Riley and Kimberlin get recognition through their work with the town fire and rescue department. “Everybody feels as if they know everyone else, just like in Andy Griffith’s Mayberry,” says Irvine. “While the rest of the state faces a shortage of water plant operators, once ours arrive, they usually stay for a long time. Clifton Forge is that special.”



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