Inflow and infiltration, aging equipment and more stringent laboratory standards are just a few of the challenges met by the staff at the Gorham Wastewater Treatment Facility.

This small plant with just two operators has achieved big things, including a 2012 U.S. EPA Regional Plant Excellence Award for achievements in reducing infiltration, replacing and maintaining aging equipment and consistently meeting permit limits.

The 0.75 mgd (design) secondary extended aeration plant is owned by the Gorham (N.H.) Water and Sewer Department, overseen by three commissioners. Their unwavering support has made a world of difference for the treatment plant and the 3,000 residents it serves. “Our commissioners, Lee Carroll, Roger Goulet and Ted Miller, have worked in the water and wastewater fields and understand the business,” says plant superintendent Dave Patry. “They make sure we get what we need.”

The EPA award announcement noted that support and cited Patry and chief operator Kurt Johnson for exceptional work. “We worked hard to reduce much of the infiltration, and we also replaced the main control panel when it could no longer meet EPA and state Department of Environmental Services regulations,” he says.

Vinnie Melendez, wastewater specialist with the Granite State Rural Water Association, who assisted the plant staff on the infiltration issue, observes, “This is one of the best facilities I work with in the state. They are proactive instead of reactive, and are doers instead of talkers. These guys work really hard.”

Plant effluent averages 8.2 mg/L BOD and 3.4 mg/L TSS. Says Johnson, “The plant operates very well. It’s all about the dissolved oxygen process control. We monitor DO levels daily using a Hach LDO meter to ensure proper aeration.”

Dealing with I&I

Gorham, in New Hampshire’s White Mountains, caters to summer tourists visiting the area’s campgrounds and motels. Built in 1980, the treatment plant is near the Androscoggin River and is susceptible to I&I during heavy rains.

The water and sewer department began an aggressive I&I study in 2005 after the DES declared that the treatment plant had reached design capacity. Granite State Rural Water conducted a townwide smoke test survey to help locate infiltration sources. “The survey showed several areas that needed repair, and we began immediate work,” recalls Patry. In December 2006, the DES placed a moratorium on new sewer connections.

Says Patry, “At this point, the department was working on I&I problem areas by replacing sewer mains and manhole structures as needed. In 2008, the DES recognized the work we had completed and saw that we had reduced influent flows at the wastewater plant, so they lifted the moratorium.”

In one neighborhood, department staff discovered an old sewer main contributing 50,000 to 100,000 gpd of infiltration even under dry conditions. “Fixing that was a huge help,” says Patry. To date, department staff have replaced 12,345 feet of sewer mains, 17,709 feet of water main and 87 manholes. “That’s quite an accomplishment for a department of three water and sewer collection system and distribution employees,” says Patry.

Wearing many hats

Infrastructure replacement is just one of the staff’s accomplishments. Besides the wastewater treatment plant, they operate and maintain a slow sand filtration water treatment plant, the wastewater collection system, the water distribution system, two reservoirs and the separate Gorham Hill Spring water system.

During sewer main replacement, the department did its own blasting. “There was a significant amount of ledge that needed blasting,” says Patry. “I received my blasting license in 1992, and I purchase the explosives and detonators for the department. By doing the blasting in-house, we were able to save thousands of dollars.”

The plant’s two operators do all the sampling and laboratory testing. Its certified lab began testing potable water samples in 1995 and accepts samples from all over northern New Hampshire. In 2005, the lab was upgraded to meet new National Environmental Laboratory Accreditation Program standards, which included biannual proficiency testing, annual onsite assessments and personnel qualifications.

“We perform about 650 water samples a year, and the operators spend an hour or two each day just for sampling,” says Patry. “It involves a lot of paperwork, and every year we have to apply to be recertified.” In 2013, the department generated $17,000 in revenue from water sample testing. That includes DES-required water testing for campgrounds, motels and hotels. The plant also accepts septage from surrounding communities for an additional $23,000 in yearly revenue.

Extended aeration

Before the plant was built, raw sewage from Gorham flowed directly into the Androscoggin, Moose and Peabody rivers and Moose Brook through 31 outfalls. Planning for the new plant started in 1974, and construction began in 1978. The plant started up in late 1980; Metcalf & Eddy provided construction supervision, startup and operator training.

The plant has been upgraded several times. In 1994, a JWI plate and frame filter press (Evoqua) for biosolids dewatering replaced a problematic belt press and allowed the plant to meet new regulations for higher percent solids at the local landfill. In 2002, 100 hp centrifugal blowers (Hoffman & Lamson) with energy efficient motors were added, and a new channel grinder (JWC Environmental) was added in 2010.

Raw water enters the operations building basement and passes through a coarse rack bar screen. It is pumped with two Passavant spiral lift pumps (Bilfinger Water Technologies) to the first floor preliminary treatment room. The wastewater flows through a channel grinder (JWC), then passes through a grit collector (Weir Specialty). Solids are pumped with a sludge pump (Moyno) to a grit separator and classifier, and the grit is disposed of at the town’s landfill.

Storage (8,750-gallon tank) and pumping (10 gpm diaphragm pump) facilities handle incoming septage deliveries, which are metered into the influent wastewater flow upstream of the comminutor. Degritted wastewater flows to the two aeration tanks (Sanitaire – a Xylem Brand), then to two settling tanks (Ovivo). Clarified effluent is disinfected with sodium hypochlorite before entering the 30-inch diameter, 1,250-foot outfall line that provides adequate chlorine detention time before discharge.

Staying on top of it

Maintaining the 35-year-old plant can be a challenge. “We do three to four hours of maintenance every day just to stay on top of it, and we learned on our own how to maintain and replace equipment,” Patry says. That has included rebuilding pumps, installing new variable-frequency drives on return activated sludge pumps and painting clarifier domes. In 2005, operators applied a new protective Zebron coating to the six concrete aeration tanks when the aggregate deteriorated.

Operators use their ingenuity to solve problems. In one case, the clarifiers were not dispersing water accurately into the outfall during high-flow conditions. “The clarifiers would flood, and that caused unauthorized discharges,” says Patry. “The staff suggested that the venturi tube on the 16-inch effluent line in the effluent chamber, which measured effluent flow from the plant, was undersized.”

Although the department’s engineering consultants confirmed that the venturi tube was properly sized for the plant’s maximum flows, the problem continued. Since there was no way to shut down the effluent flow, plant staff sent a sewer camera into the venturi tube to investigate the interior condition of the throat valve, and found it in excellent condition.

“The staff came up with the idea of removing the venturi tube and inserting a 16-inch spool piece in its place, then changing our flow measuring capabilities to an ultrasonic transducer near the effluent weir plant,” says Patry. “That solved the problem.”

The plant team also replaced the old console control panel in 2012. Outdated and unreliable alarms no longer complied with EPA and DES regulations. The wiring had become brittle and could have caused fire and permanent failure. Says Patry, “We upgraded to a simple panel with a computer screen connected to the SCADA system so we can remotely monitor the plant and control alarms.”

Thankful community

Department staff members conduct annual tours of the water and wastewater plants for anyone, including middle school students. “We’ve done this for the past 12 years,” says Johnson. “The kids are excited to learn about water and wastewater treatment, and we even get thank you letters.”

Johnson also appreciates the support of the community: “Everyone knows we perform these projects in-house, which saves them money.” Granite State Rural Water has also been supportive. Says Patry, “They provide operators with networking opportunities, technical assistance and training at the local fire station.”

Melendez adds, “If we see the operators struggling with an issue, or if regulators are going to visit the plant, we try to help. Sometimes staff members feel they are the only ones dealing with an issue, but they’re not alone.”

Loving the job

Patry has been with the department for 30 years, Johnson for 17 and Brian Rivard, assistant operator, for 16. “Turnover is not a problem here,” says Patry. “They love the area, they love working here and they all get along well.”

Patry feels the plant is in good shape: “We’re caught up now and taking a breath of fresh air. We have more than enough capacity, and with a new wastewater permit, we don’t expect any regulatory changes soon. Our future is the staff. They’re everything. I can’t say enough about the work they do and how they do it.”

More Information

Bilfinger Water Technologies, Inc. - 800/833-9473 - www.water.bilfinger.com

Evoqua Water Technologies, LLC - www.evoqua.com

Hach Company - 800/227-4224 - www.hach.com

Hoffman & Lamson, Gardner Denver Products - 866/238-6393 - www.hoffmanandlamson.com

JWC Environmental - 800/331-2277 - www.jwce.com

Moyno - 877/486-6966 - www.moyno.com

Ovivo USA, LLC - 512/834-6000 - www.ovivowater.com

Weir Specialty Pumps (WEMCO) - 801/359-8731 - www.weirpowerindustrial.com

Xylem - 704/409-9700 - www.xyleminc.com

Zebron - 800/824-4214 - www.zebron.com