When a contract operator took control OF the City of Biddeford’s clean-water plant, both sides knew the arrangement was temporary.

OMI, the operations arm of CH2M HILL, signed a contract to operate the city’s treatment plants, collections system and lift stations in the early 1990s. In the years that followed, the city resumed operations, step by step.

The Biddeford Waste Water Treatment Facility came back under the city’s charge in November 2009, and since then the plant team, led by Jeff Demers, assistant director of Public Works, Waste Water Division, has made numerous improvements that boost efficiency and performance.

The city didn’t leap back in blindly. Demers, with Guy Casavant, director of Public Works, and Tom Milligan, P.E., city engineer and director of wastewater, first mapped out a strategy that began with building a team of professionals, each with essential skills, from plant and lab operation to trades like electrical, carpentry, plumbing and instrumentation.

The payoff is that the team has made substantial modifications and upgrades largely in-house. “The city knew and OMI knew that they weren’t here forever,” Demers says. “They were here to get the city back in compliance, and they did that well. Once they got things situated, the city realized that with good staff we could run the plant again. The team we put together has saved the city a bunch of money. The work they’ve performed is just amazing.”

Getting past trouble

Biddeford, a Maine beach community of about 20,000 half an hour south of Portland, has a 3.5 mgd (design) activated sludge treatment plant for the city proper and a 30,000 gpd rotating biological contactor plant that serves oceanfront properties in a tidal area known as Biddeford Pool, about six miles south of downtown. Demers and his team also operate and maintain nearly 40 miles of collections system and 24 pumping stations.

The city once was home to a large mill district with shoe, blanket and other clothing and textile manufacturing. Most of those industries have moved out and some mills have been converted to housing units, shops, restaurants and breweries. The sewer network has about 4,020 residential, 460 commercial and 12 significant industrial users.

The main treatment plant was built in 1962. By the early 1990s it had fallen out of repair and out of date and its effluent out of compliance. From 1996 to 1998, under OMI’s direction, Biddeford completed a major treatment plant upgrade, ordered by the U.S. EPA. The new plant included an activated biotower upstream of two aeration basins, followed by a pair of secondary clarifiers. “All the buildings were replaced except one,” says Demers. “The one that stayed was the dewatering building, which ended up with two belt filter presses.”

Tuning the process

Engineers chose the biotower for its ability to treat industrial flows and resist toxic shock loadings. “BOD and TSS were in the low teens after the tower,” says Dan Laflamme, chief operator. “At that point the aeration basins were almost a polishing treatment before the clarifiers.”

In 2012, seeing greatly reduced industrial flows, the plant team took the biotower offline. “We get good treatment straight from the basins and we save a lot of energy,” says Laflamme. “We used to run two or three pumps under normal flow. We used a 75 hp pump just to lift influent to the top of the tower. Now we typically modulate one pump [to feed the aeration basins].”

Treatment starts with a pair of traveling bar screens with rakes (Lakeside Equipment), each designed for 10 mgd, the plant’s peak design flow. Next comes a two-channel PISTA Grit system (Smith & Loveless), also sized for 10 mgd. Water from that system enters a single channel leading to an influent pumping station with four 75 hp pumps (Flygt – a Xylem Brand).

A 125 hp centrifugal blower (Hoffman) and a 100 hp turbo blower (APG-Neuros) feed air to the aeration basins. The city has ordered two EE-pac high-efficiency screw blowers (Universal Blower Pac) with an operating range of 400 to 2,000 scfm at 8.3 psig to replace the Neuros blower; the Hoffman unit will remain as a backup unit.

The blowers feed air to the basins by way of fine-bubble diffusers (Sanitaire). The flow then proceeds to two 80-foot-diameter secondary clarifiers (Ovivo and FMC). Secondary effluent is disinfected with chlorine and dechlorinated with sodium bisulfite. Final effluent discharges to a tidal zone of the Saco River.

Two rotary lobe pumps (Boerger) alternately draw waste activated sludge from the clarifiers and deliver it to a pair of 20,000-gallon holding tanks, “small for a facility our size,” says Demers. That material is dewatered on a pair of inclined screw presses (Huber Technology). The resulting cake at 24 percent solids (350 dry tons per year) is hauled to a landfill by Public Works staff. The plant team is exploring composting at a nearby contract facility.

Resuming control

Demers came to Biddeford in 1995 as an OMI employee; the city hired him a year later as it took over responsibility for the collections system. “We worked on the system for a couple of years and made some nice improvements,” Demers recalls. “A few years later the city decided to take the pump stations back. During that process, we implemented a new SCADA system and did some pretty intensive vacuuming of the sewers. Our crew received a 2006 achievement award from the state Department of Environmental Protection [DEP].”

In 2002, the city resumed operations of the Biddeford Pool treatment plant. “In 2009, we decided to take on the big bear here at the main treatment facility,” says Demers. “The challenge was showing that we could do it, and do it cost-effectively. I can tell you we have done both. The DEP is very happy with what we have done here, and the city fathers are happy as well. In our five years running it, we have saved about $850,000 in operating costs.”

A strong team made it happen. “Guy, Tom and I sat down and figured out what we needed to run the plant,” says Demers. “We looked at our staff and the skills they had, looked at the budget, and came up with the positions and the skills we thought were necessary.”

Then came the hiring: “We knew, No. 1, that we needed a good person who could wrap arms around operations and compliance. That’s where Dan Laflamme came in.” At the time Laflamme was an electrician for the South Portland treatment plant. He had worked on a number of treatment plants and pump stations while with a construction company and while self-employed for several years as an electrical contractor.

Demers observes, “Dan is a great operator and his knowledge from working at several plants and seeing how they’re run has really helped us a lot. And if we have an electrical issue we need to iron out quickly, he will put his electrician’s belt on and help us.”

The city also brought on two OMI employees: Tony Ellsworth, lead operator who also keeps the plant’s safety program on track, and Alex Buechner, lab technician who has helped keep the facility in compliance through various upgrades while helping reorganize the maintenance program and the operations daily manual.

“We were also fortunate to hire Steve Collomy as a maintenance technician,” says Demers. “He had worked 17 years with the DPW and had spent two years in North Carolina working on a NASCAR team. He’s an excellent fabricator and welder, the kind of all-around guy you need in this environment.”

Jon Koestner came on board in a utility maintenance and press operator role. A plumber by training, he previously worked for a plumbing contractor. “We were doing a lot of plumbing work in this plant,” says Demers. “Jon has surprised Dan and me with some of the projects he has completed for us.”

Jim Lewis, plant operator and pump station technician, spends two hours a day at the Biddeford Pool plant and the balance at the main plant and in the field. He also helps with electrical issues, carpentry and handyman projects. Brian Phinney is the environmental code officer and industrial pretreatment coordinator. Steve Demers (no relation to Jeff) is an assistant press operator and groundskeeper.

Getting to work

The team has made multiple and far-reaching improvements. The biggest was a dewatering upgrade that replaced two aging belt filter presses with the screw presses. “People had to watch the filter presses constantly and there were a lot of breakdowns. They were producing cake at about 15 to 16 percent. We wanted to improve that and save money in hauling.”

The new presses run largely unattended and dewater around the clock, spreading out the power consumption as opposed to operating during the day shift and driving up on-peak electric power demand. The two presses provide redundancy to protect the plant’s 40,000-gallon total sludge storage capacity.

“We waste about 15,000 gallons per day, so we can’t be down for very long,” Laflamme says.

“In addition to the screw presses, we bought a rotary drum thickener (BDP Industries). If we ever get in trouble for sludge storage, we’ll be able to thicken 1 percent solids waste activated sludge to 5 percent and get five times the room.”

The team completed the installations in-house with some outside engineering support and with contractors’ help on the concrete and electrical work. “Our team did the rest — laying the electrical conduit, all the steel work, the piping, the setting of the presses, the conveyors,” Demers says.

More improvements

That’s just one example of the team’s ingenuity. They also made changes that helped reduce combined sewer overflows (CSOs) to the river. “There was a float arm and a modulating gate valve that limited our flow so that the plant wouldn’t get washed out,” says Laflamme. “It limited the flow to between 9 and 10 mgd, above which there were times we would bypass.

“We were comfortable that the plant could handle more flow. So we installed a gate valve with an actuator. Now, with remote access from our SCADA system, any of our operators can go online and modulate that valve. So we’re inclined to take flows of up to 14 mgd, while keeping an eye on our blankets. That has cut down drastically on our CSO events.” A 2-million-gallon CSO capture tank provides further assurance against bypassing. “We’ve had maybe two or three events in the past three years,” Demers says.

The team’s other plant improvements include:

• Adding automated valves in the two influent channels so that each channel can be closed for maintenance when required. Another valve just before the influent screen allows the entire flow to be diverted to the CSO holding tank in case the plant receives a toxic shock load.
• Replacing a process water skid (for in-plant effluent reuse) that was an “energy hog” with three 30 hp pumps that ran regardless of water demand. The new skid has three 15 hp pumps with variable-frequency drives that provide pressure and flow only when needed.
• Building a new SCADA system with FactoryTalk software (Rockwell Automation) with help from a local contractor. “We walked him through what we wanted to see on the screens and how we wanted the ladder logic to work,” says Demers. “He made it happen for us.”
• Changing the waste activated sludge piping so that material for dewatering can be drawn from the holding tanks or directly from the clarifiers.
• Adding a Monashell system (Anua) that processes foul air from the sludge storage tanks and dump container area, reducing odor issues in the plant’s residential neighborhood.

Keeping it together

With the plant on a sound footing, Demers concentrates on keeping his team in place. Friday meetings provide a place to review the next week’s tasks and to air out issues as a group.

“When we put this team together, we decided to offer competitive rates of pay,” says Demers. “Our people are paid well, they get a great benefit package and we treat them well. Everybody is a team player. We aim to keep these people around for the long term.”

Laflamme observes, “I wish I could put into words how happy I am with the team. As a Biddeford taxpayer, I’m pleased to know the people working here have the best interests of the city and the plant at heart. I’ve seen a lot of plants, and I really like the attitude and the motivation I see here.”