Petaluma to turn sewage into truck fuel

Using the latest technology costing millions of dollars, Petaluma will soon be turning to a new source of fuel for powering its fleet of garbage trucks - your toilet.

The California Energy Commission announced this month it was awarding Petaluma $3 million to build a natural gas collection and automotive fueling station at the Ellis Creek Water Recycling Facility, part of an overall $15 million expansion expected for completion in 2018.

The broader work will increase capacity while allowing the plant to take high-strength waste from local industry, creating a scale that Petaluma Environmental Services Manager Leah Walker said was sufficient to process solid waste from city residents and businesses into the foreseeable future.

The project will allow Ellis Creek to keep pace with the massive growth in local breweries, dairy processors and others - companies that generally truck their high-strength waste elsewhere for treatment. Shortening those trips will lower greenhouse gas emissions, as will the eventual switch from most of Petaluma’s diesel-powered garbage trucks to those running on biologically derived natural gas.

“We are very excited to be given the opportunity to beneficially use a previously discarded energy resource to the advantage of our citizens and our environment,” said Dan St. John, Petaluma’s director of public works.

Named as the first runner-up following an initial grant application to the Energy Commission in 2014, Petaluma scooted up a notch to a winning position after the exit of another bidder, Walker said. The Energy Commission announced Petaluma’s award on March 9.

Adding the ability to treat high-strength waste will allow the plant to produce enough methane gas to replace an anticipated 117,000 gallons of diesel fuel annually, Walker said. With fewer truck miles traveled and more fossil fuel remaining underground, the work will allow an annual reduction of around 3,030 tons of greenhouse gases emitted.

“We thought we had this really compelling project, to take our locally produced methane gas from the wastewater of our local industry and turn it into fuel for our garbage trucks,” she said.

The ability to handle that high-strength waste comes as welcome news for the city’s food and beverage manufacturers, companies that are estimated to pump around $1.3 billion into the broader Sonoma County economy while directly employing as many as 1,500 people, according to 2014 study commissioned by the city of Petaluma.

Costs for trucking between seven and 10 loads of waste every day have amounted to between $1.5 million and $2 million annually for Lagunitas Brewing Company alone, said Leon Sharyon, chief financial officer.

Facing massive demand for its hoppy craft brews, Lagunitas included an advanced on-site wastewater treatment facility as a way to move forward with expanded capacity in Petaluma. While the technology is expected to process the majority of the brewery’s organic waste by this summer, Sharyon welcomed the backstop of a local municipal disposal option, something he argued was likely to attract new business to the city.

“That’s going to be the win for all of those businesses,” he said.

With plans for its own expansion, Petaluma Poultry is likely to consider the option over disposal outside of the city, said General Manager Mike Leventini.

“It will likely be a viable option for us that is closer to home. It’s always nice to have the opportunity to take trucks off the road,” he said.

The 2014 study projected that the ability to process high-strength waste in Petaluma could prompt the addition of 307 direct jobs from existing companies. Other jobs anticipated to come from demand created outside the companies themselves amount to more than 1,200 new positions, contributing to a combined windfall of $310 million in direct economic activity.

The full expansion will be funded through a combination of the state grant, mitigation fees from sources like the Lagunitas project and sewer fees, Walker said.

“This will allow us to better support our local industry, saving them money and time. It will also allow us to attract other businesses that require ways to discharge high-strength waste,” said Ingrid Alverde, the city’s economic development manager.

While improving the plant’s solid waste capacity, future work may eventually be needed to accommodate increases in liquid waste, Walker said.

Completed in 2009, the Ellis Creek facility treats around 5 million gallons of wastewater every day, according to information from the city. It replaced a 70-year-old treatment plant on Hopper Street, and serves both Petaluma and Penngrove.

The high-tech facility was considered a major improvement over its aging predecessor, but was designed and built before an unexpected explosion of growth for food and beverage manufacturing in Petaluma and across Sonoma County, Walker said. With similar concerns cropping up at Santa Rosa’s Laguna Treatment Plant, it wasn’t long before Petaluma officials began to discuss ways to improve functionality at Ellis Creek.

“It was designed at a time before our industries were going as big as they are,” Walker said. “It was like a bottleneck.”

When the expansion is complete, companies will be able to drop off various types of “slurry” directly at the Ellis Creek plant. Plant operators will gradually add that sludge to regular municipal waste in a tank known as an anaerobic digester, where microbes will break down the organic material.

Today, plant operators use a flare to burn off much of the methane produced as a byproduct of that process. The expanded plant will instead capture that gas, compress it and make it available to run vehicles.

A number of other wastewater plants, including the Laguna plant, use biologically derived methane to run huge generators that help power their own operations. Yet the automotive fueling approach in Petaluma was considered more cost-effective due to technological improvements, and was made logistically easier by the city’s ownership of both the plant and the fleet itself.

Walker said the details of the fueling component are still under development, with options that include an on-site or mobile fueling station. The city had originally expected to add natural gas-powered buses to its transit fleet, but dropped those plans in favor of hybrid vehicles due to the timing of the project.

Buses might be added one day in the future, she said. It is not yet known whether the fueling station will serve the public.

When operational, the compressed natural gas will be the second product derived from the operations of the Ellis Creek wastewater plant. The plant has a hugely successful and expanding program to sell highly treated, non-drinking water for irrigation around Petaluma, a byproduct whose sale helps to offset sewer rates as a whole, Walker said.

The so-called purple pipe infrastructure received heightened attention at a time of mandatory water use restrictions, allowing full-scale irrigation at locations like the Rooster Run Golf Course at a time of major drought. The system is being expanded to increase both reach and capacity, and will soon incorporate the Petaluma campus for Kaiser Permanente, she said.

Walker noted that Santa Rosa has also been working to add a high-strength waste component at the Laguna plant, but that there was plenty of material in food-friendly Sonoma County to go around.

“We believe there’s enough high-strength waste produced in this county to be enough for all of us,” she said.

(Contact Eric Gneckow at eric.gneckow@arguscourier.com. On Twitter @Eric_Reports.)