During Sid Fredrickson’s first year as Coeur d’Alene wastewater superintendent, part of the answer to a challenging phosphorus limit was a process chemical mixing tank stirred by an electric fishing motor.

Twenty-three years later, the plant’s phosphorus control technology is, to say the least, a bit more sophisticated. What hasn’t changed is the dedication Fredrickson and his team bring to quality performance in the city’s treatment plant and collections system.

They’re keeping a 75-year tradition of excellence: Coeur d’Alene’s plant, commissioned in 1939, was among the first in the nation to provide secondary treatment. Today the team in Coeur d’Alene, a city of 46,000 in Idaho’s panhandle, is gearing up to meet a new and extremely stringent effluent phosphorus limit.

Fredrickson, nearing retirement, plans to stay on board at least long enough to get the plant’s full-scale pilot membrane microfiltration tertiary treatment system commissioned and optimized. Whenever he chooses to step down, it won’t be without recognition: The Pacific Northwest Clean Water Association presented him with its 2013 William D. Hatfield Award.

Teacher by training

Fredrickson tells people he comes “from the Mountain West.” If that’s not highly specific, it’s because his father was an air traffic controller stationed in places from Wyoming to Alaska. “I was born in the little town of Richmond in northern Utah, but we made 13 major moves in my first 12 years,” says Fredrickson.

He graduated from high school in Dillon, Mont., and also earned his bachelor’s degree in secondary education there (1970) at what is now the University of Montana — Western. He taught chemistry, physics and math in Montana public schools for three years, then spent 10 years with a Montana consulting engineering firm, in the process serving as a resident inspector on a complete rebuild of the treatment plant in Kalispell.

After 2 1/2 years as public works director and city engineer for Whitefish, Mont., he moved to Coeur d’Alene as streets superintendent, also in charge of the stormwater system. He became wastewater superintendent in May 1991.

“I had done a lot of plant startups and operator training while with the engineering firm,” Fredrickson says. “I’d been involved in water quality with Coeur d’Alene because we had a lot of issues with stormwater. So it wasn’t as if I was moving very far away from the tree.

“At the time someone asked me, ‘Why would you want to make that move?’ I said, ‘Why would I want to get away from the general fund and having to fight for tax dollars, and move to an enterprise fund where I’ve got the money to do what needs to be done? Gee, I can’t imagine why I would do that.’”

Process innovation

Coeur d’Alene’s treatment plant has a nominal 6 mgd design flow but is derated to 4.2 mgd with nitrification for ammonia removal. The dry-weather flows average 3.8 mgd. Secondary treatment consists of trickling filters followed by a solids contact process.

“The detention time in trickling filters, particularly those like ours that use plastic media, is very short, only about 10 minutes,” says Fredrickson. “So to augment that we have sludge reaeration basins that end up feeding a solids contact tank. We blend reaerated secondary sludge with the trickling filter effluent. That becomes the solids contact process.

“We’re giving the rejuvenated microorganisms enough time to be in contact with the trickling filter effluent to further reduce the BOD, particularly the dissolved BOD. We pull activated sludge off the bottoms of the secondary clarifiers and can send it in two directions. We can waste it to our digesters, or we can recirculate it through the sludge reaeration basins.

“If the total plant flow is Q, we have about 0.3Q going through solids reaeration. The process was developed by Brown and Caldwell. It has its advantages. There aren’t many operational difficulties with it. It handles shock loads very well.” Final effluent is disinfected with chlorine, dechlorinated with sulfur dioxide and discharged to the Spokane River.

Wasted solids are anaerobically digested, dewatered to 25 to 26 percent solids in a high-speed centrifuge (Alfa Laval Ashbrook Simon-Hartley) and transported to an aerobic static pile composting facility about 2 1/2 miles away. The compost is sold wholesale to nurseries and landscapers. “It’s an environmentally friendly way of handling biosolids without taking up valuable landfill space,” Fredrickson says.

Immediate challenges

The treatment process took hold of Fredrickson’s attention from his first days as superintendent. “My first year was also the first year we had to initiate phosphorus removal,” he says. “Starting in June 1991 we had to achieve 85 percent reduction, and we didn’t have anything in place to do that. So it was a scramble.

“We rented a 2,000-gallon tank, purchased some small peristaltic feed pumps and started buying alum and adding that to our secondary clarifier splitter box. We added liquid polymer to help the flocculation process, and that also helped with phosphorus removal. We mixed the tank contents with a Minn Kota electric outboard motor. We were having alum deliveries almost every other day.

“We still do alum addition, but now we split our flow of alum. Roughly half of it goes to the head of our preaeration grit removal basin. The other half goes to our secondary clarifier influent splitter box. The reason we split the flow is that by going ahead of the primaries we decrease the loading on our trickling filters and increase nitrification.

“We also have added integrated fixed film activated sludge units. It’s a cloth media system installed in our solids contact basins and it provides a home for the nitrifying bacteria. So we’re increasing our nitrification with those units. We do have an ammonia limit in our permit at 10 mg/L based on our current flows.

“Our phosphorus limit had been 1.0 mg/L or 85 percent removal, whichever is less. That changed with the issuance of our new permit last November. We now have a nine-year compliance schedule to achieve a seasonal average of less than 50 µg/L phosphorus. That’s why we’re building our tertiary unit.”

Targeting phosphorus

The Coeur d’Alene team pilot-tested three 50,000 gpd advanced tertiary filtration units over about 18 months: an upflow sand filter, a membrane bioreactor and a ZeeWeed membrane microfiltration system (GE Water & Process Technologies), which they ultimately chose for a full-scale test.

“We found that with the tertiary membrane filter, if we put a return activated sludge line between the membrane tank and the chemical mix tank, we actually make a mixed liquor and achieve nitrification as well as phosphorus removal,” says Fredrickson.

“The membranes get scour air 100 percent of the time, so by looping the sludge, basically drawing off the mixed liquor from the membrane tank and returning it to the large chemical mix tank, we create an activated sludge ahead of the membranes that provides nitrification. Then, by adding alum to the chemical mix tank, we also precipitate the phosphorus, and of course we’re removing that in the membranes as well.

“With our engineers [HDR], we are cautiously optimistic that this system will scale up. It’s one reason we’re sizing the membrane filter basins so they will be easily expandable to 5 mgd. We’re installing only 1 mgd of membranes at this stage just to make sure that we prove our ability both to remove phosphorus and to nitrify.”

Out with odors

The team faced a couple of more immediate challenges with odor control and compost facility efficiency. In the late 1990s after odor complaints started, team members interviewed residents of a nearby neighborhood and learned that, “We were about two weeks out from getting sued,” Fredrickson recalls.

After a study identified the biggest odor sources, the team took action. Measures included collecting foul air from the sludge thickeners, belt filter presses and centrifuge and routing it through the two trickling filters (half through each) followed by compost-bed biofilters.

The 14-acre biosolids compost facility, built in the late 1980s, was among the first in the Northwest. “Back then the experts didn’t know much more than we did about building a compost facility in the type of climate we have,” Fredrickson says.

“We did a major revamp of the process for mixing the wood chips and biosolids. We put in a gyratory screen to make three fractions of compost: 3/4 inch and larger to go to the recycle pile, less than a 1/4 inch to become finished compost, and material in between to be run through a hammermill and ground up. That would produce an additional 1,000 cubic yards of compost per year.

“It seemed like a good idea, but Mr. Fredrickson didn’t check how much power the hammermill would consume. Long story short, we generated an extra $10,000 a year in revenue but it cost us $11,000 in power. We don’t do that anymore. Now we have a single trommel screen with a 1/4-inch opening so that material either goes to finished compost or goes to the reclaimed chip pile. That works much better.”

The static compost piles are enclosed and foul air is fed through a compost biofilter. The site is staffed by Paul Mitchell, lead worker, and Clark Thomas, operator.

Management styles

To keep processes and the team working smoothly, Fredrickson combines two approaches to management. Managing by exception means spotting “out-of-spec” processes or behaviors and taking quick corrective action. Management by walking around means being visible, available and approachable: “If you see something that looks good, compliment the people on it. If you see something that looks bad, deal with that in private.”

The team’s longevity attests that those approaches work: The wastewater department staff represents a collective 326 years with the city and 520 years in the trade, an average of nearly 21 years per employee.

Plant team members include Don Keil, assistant superintendent; Jim Remitz, capital program manager; Mike Becker, utility project manager; Torri Green, administrative support; Casey Fisher, chief wastewater operator; Mark Moore, Ben Martin, Marc Branscome, Andy Williams and Mike Taylor, operators; Mike Zwiebel and Aaron Camp, maintenance mechanics; John Dearth, lab/pretreatment supervisor; and Dave Hauser and Susan Whittier, lab analysts.

Adding to the team is one of Fredrickson’s current challenges. “We’re looking to hire additional people in the plant because as we put these complex processes online, it will take more effort to make sure everything is running right,” he says.

“I can’t go out on the market and say, ‘I want an experienced Class III or Class IV operator who knows all about membranes and meeting 50 parts per billion phosphorus.’ They don’t exist.” Instead, he looks for sharp people with some wastewater background who want to learn, don’t have outsized egos, get along well with others, are hard-working and dependable, and ideally have a special skill, like pipefitting or instrumentation. “That’s where we’re going to get our people. That’s how we’re going to increase our ability to do those complex tasks.”

Advice to peers

Some three decades in municipal and utility service have taught Fredrickson good lessons that he’s glad to share with colleagues. “When dealing with local politics — and municipal treatment plants always do — it helps to forge good relationships with the elected governing body.

“You have to build trust. They need to trust that you are doing the right things, otherwise you won’t get what you need to do the job. You also have to understand that there are more than two colors when you’re dealing with a governing body. Everything is not black or white. You have to learn to compromise, without compromising your own integrity and honesty.”

And finally: “You need to have a good sense of humor. I don’t know how you get along in this world without it.”