The Birch Bay Water and Sewer District team finds ways to save or extract energy from almost every aspect of facilities and operations.
The Birch Bay Water and Sewer District wastewater treatment plant is small, and so are its staff and community.
In six years as operations manager for the district, based in Blaine, Wash., Mike Sowers has been given a green light to seek out improvements, even if it means spending some of his limited operations and maintenance budget.
“My philosophy is that it’s better to improve than it is to just fix things,” says Sowers. “I get a lot of support from our commissioners, our management, our engineer and the crew. The savings have built our credibility and enabled us to keep doing the things we want to do, like installing more variable-frequency drives [VFDs].”
Since 2007, the plant has reduced its energy consumption by 28,000 kWh per month. “Our bill has dropped from around $9,000 a month to $7,500 despite an increase in electrical rates and wastewater flows, and that includes adding a new lift station and installing heating and air conditioning in two buildings,” Sowers says.
Sowers says it’s hard to tell how much of the savings come from which specific projects. Newly installed power monitors will help him with that, while also helping the plant limit demand charges from the local utility. The $1,500 in monthly savings comes in handy at the district’s activated sludge plant (1.3 mgd design, 0.84 mgd average).
The plant serves the resort area of Whatcom County on the Puget Sound, where the population ranges from 4,000 in winter to 12,000 in the summer tourist season. “We’re a small community so we don’t have a lot of play in our budget,” says Sowers. “So it has a big impact. My budget is 8 percent less than it was in 2009.
“Coming from a maintenance background, I’ve seen places that don’t replace equipment unless it can come out of the capital budget. I’ll go ahead and replace it using O&M money if I have to, if it will pay for itself quickly.”
Sowers had been interested in effluent heat recovery for some time and had a chance to use it in 2009. “We were looking at replacing some old heating and air conditioning units,” he says. “We use propane, so that was costing us several thousand dollars a year. I brought up the topic to our system engineer, and he completely ran with it.”
The heat recovery system (Carrier) uses four heat pumps that recover heat from effluent at 50 to 70 degrees F. The total cost of the system was $85,000. “That’s comparable to what we would have paid for new heating and air conditioning units,” notes Sowers. “And we added air conditioning to two buildings. It’s a 1/3 horsepower pump, and only uses 5 to 10 gallons of effluent flow per minute.” The effluent is returned to the plant headworks after going through the system.
While he can’t isolate the electrical savings from other projects done about the same time, effluent heat recovery is saving about $4,000 a year in propane costs alone. “We now use so little propane that our tank was filled only once last year compared to almost monthly before,” Sowers says.
On the process side, Sowers and his team have added nine VFDs (Allen-Bradley by Rockwell Automation and ABB) to improve efficiency across the plant. VFDs are also being added to lift stations and new drum screens to optimize control and minimize energy consumption while maximizing capacity. Other improvements include:
- Automating the return activated sludge process to improve treatment and energy demand while minimizing operator attention.
- Adding SCADA dissolved oxygen control to the aeration process to enhance efficiency and save energy.
- Installing mixers at several lift stations to eliminate weekly pumping, saving labor and waste hauling costs.
- Switching from potable to reclaimed water for in-plant uses, saving 4 million gallons of potable water per year.
Other simple energy-saving measures have also made a difference. Turning down thermostats may not save a lot of energy, but it helps. So will new on-demand water heaters. “We went from a 50-gallon propane water heater in our shop to a 3-gallon tankless electric unit that was half the cost,” Sowers says. “We now have hot water within a few seconds, which also saves water.
“It’s good to start with green products such as LED lighting. But there are many ways to conserve and ‘create’ energy if one looks at every facet of the operation.” On his wish list is replacement of 1970s backup generators with high-efficiency, clean-burning engines. There are plans to switch to fine-bubble diffusers for aeration, potentially cutting energy use by 40 percent. A few small solar panels are in the works, as well.
All those changes have certainly not hurt performance. The plant has received the state Department of Ecology’s Outstanding Treatment Plant Award 12 times in the past 15 years, including the last five years in a row.