Commercial fishing played a big role in the development of Petersburg, Alaska. It also has a lot to do with successful operation of the community’s primary wastewater treatment plant.

“If you’re a fisherman, you have to work hard, and you have to work now,” says Justin Haley, wastewater supervisor. “People are depending on you.” The same ethic applies to wastewater treatment.

Haley has worked as a commercial fisherman and so have all the members of his staff.  “We’re all from here and we’ve all commercially fished, so we know what it’s like to have to work with baling wire and duct tape to keep things going,” he says. “We’ve all grown up figuring out how to make things work.”

Petersburg’s remote location, on Mitkof Island along Alaska’s Inside Passage, makes operator ingenuity necessary. It can take weeks to get parts for plant equipment, so staff members are jacks-of-all-trades. Since the new plant was started up in the late 1980s, they’ve fixed and improved nearly all the process equipment, while also servicing the lift stations and the 17-mile collections system.

That self-reliance, along with excellent performance, earned Petersburg the 2014 Plant of the Year award from the Alaska Rural Water Association.

A primary plant

The plant’s treatment process is unsophisticated but effective in compliance with its permit, which requires only preliminary and primary treatment.

At present, the plant has an exemption from secondary treatment. “The original plant built in the 1970s was a secondary plant using a bio-tower,” says Haley. “The engineers who designed it grossly underestimated the flows, mostly because they ignored I&I, which was huge. The plant never worked, and so the decision was made to bypass until they could get a functional facility.”

The U.S. EPA agreed with the decision and granted the exemption. The facility is still regulated by the EPA even though Alaska now has its own permit, because only the federal government can authorize the exemption.

Meanwhile, reducing I&I is a top priority. “Our dry-weather flows are around 0.3 mgd, and our peaks have dropped from 2.5 mgd a decade ago to about 1.7, but we still have a long ways to go,” says Haley. “We have two smaller projects coming up in the next year, and we are starting plans for two more. My hope is that by the end of the decade, an upgrade to secondary treatment will be viable in the eyes of the people who sign the checks.”

Seasonal flows

Wastewater enters through a headworks with two Hycor rotary fine screens (Parkson Corp.) that operate alternately. Screenings are dewatered on a press, placed into a hopper and taken once a week to a landfill 2 miles away. After screening, wastewater passes through a Eutek TeaCup centrifuge grit removal process (Hydro International).

In summer, when tourists and employees of the town’s fish processing plants boost the population from 3,000 to about 5,000, a dose of chlorine is added before the wastewater enters the primary sedimentation basins. While chlorine is not required by the plant’s permit and is removed before the treated water is discharged, the dose helps the plant control fecal coliform.

The rectangular primary basins (12 by 60 feet and 10 feet deep) are equipped with chain and flight mechanisms. After treatment, the effluent is discharged through an outfall pipe that runs 1,000 feet into Frederick Sound, to a depth of about 100 feet.

Solids are stabilized in an aerobic digester equipped with Flexair fine-bubble diffusers (Environmental Dynamics). A belt press (Parkson Corp.) dewaters the material, which is then landfilled.

Petersburg easily meets its discharge permit, producing water with an average BOD of 84.7 mg/L (46.3 percent removal) and TSS of 39.7 mg/L (76.3 percent removal). Fecals are about 550,000 per 100 mL, versus the permit of 1 million. Dissolved oxygen averages 5.6; pH is 7.0.

Portions of the plant are controlled by a small SCADA system supplied by Rockwell Automation/Allen-Bradley. “We’re phasing out an old system,” says Haley. “The new one has been online only a year and right now controls just one of our lift stations.”

Self-service

When equipment needs modification or repairs, Haley and operators Dennis Jones, Blake Buotte, Mike Bell and Aaron Greinier do it themselves. All the plant’s process equipment has required attention at some point.

The staff has made minor modifications to the rotary fine screens. “We made changes to reduce wear and tear on the bearings,” Haley says. “We basically removed the automatic cleaning mechanism. It simplified their operation.”

The staff also replaced the original grit-removal centrifuge. The original was made of carbon steel, which rotted out and leaked from the bottom. The team ordered a new stainless steel model and installed it, even though it was a hassle. “The screenings screw conveyor runs over the top of the centrifuges, and we couldn’t take that out, so we had to squeeze the new TeaCup unit in beneath it,” says Haley. “We cut the old one up into pieces. It took us about a week; it was quite an operation.”

Haley’s team wasn’t satisfied with the sludge removal process in the primary basins, so they reworked that process, as well. “There was just a single pump pulling from the bottom of the sumps in both clarifiers, and it tended to pull one side, but not both,” Haley says. “We re-piped the system so we could control where the sludge was coming from. Before, we had no way of directing the flow.” Now one pump can pull from collection points in each clarifier.

Staff members also added a transparent section of PVC piping on the sludge line so they can observe sludge consistency.

Versatile team

The Petersburg team’s ingenuity extends to operating the water plant and caring for the distribution and collections systems. “Mike is the water operations supervisor, Blake is our water system operator, and Dennis is our wastewater operator,” says Haley. “We share Aaron Greinier. But we all rotate and go where we are needed.”

In other words, everyone is involved in everything: “It’s a very full plate with a very small crew.” The village’s location on the rocky northern tip of Mitkof Island presents unique challenges to collections. “It’s fairly hilly ground, so we operate and service 20 lift stations.” The rocky ground makes it too costly to blast to obtain grade. Some lines are 5 feet deep, and the deepest is only 20 feet.

The geology and remote location also make trenchless boring and lining infeasible. “It takes contractors and equipment too long to get here,” Haley says. As a result, his crew handles it. In one recent project, they relocated about 2,000 feet of ductile iron force main that ran along the harbor and was getting exposed because of the low tides on the island. The pipe was corroding and in danger of rupturing. Crews are relocating it beneath a newly paved road and using HDPE pipe.

Most of the sewers date to the 1970s and consist of ductile iron, PVC, asbestos-cement or straight cement construction. “We actually spend most of our time on collections, cleaning, inspecting and dealing with grease,” says Haley. “We use a Vactor unit for cleaning and jetting. We have the only septic pumping vehicle in town. We’re constantly working on improvement projects.”

To protect the sewers and receiving waters, the town has started a household hazardous waste collection program. “It’s a two-day weekend drop-off,” says Haley. “We do it in conjunction with the sanitation department, and it has gone over well.”

Flushable wipes can be a challenge. “Like everybody else, it’s a problem for us,” Haley says. “We’re at a lift station every week cleaning out flushables. With our small crew, our time would be better spent elsewhere. It could be avoided if people would pay closer attention to what they flush.”

Varied backgrounds

While fishing is in the background of all Petersburg operators, they’ve carried over other skills from previous jobs that prove invaluable. “Dennis was an iron worker before coming here,” says Haley. “He’s a certified welder. Mike worked in the logging industry and is a whiz with construction equipment.

“Wastewater operators in a small town need to know a lot, whether taking apart a pump, or doing some welding or troubleshooting electrical systems, sometimes for other city departments. Most of the time there are only two of us here at the wastewater plant. The work involves a lot of variety. We’re not afraid to get dirty.”