A short stroll from the marshy sanctuaries of the Palo Alto Baylands, inside a concrete tower off Embarcadero Road, lies an inferno that would make Dante gag.
For 42 years and counting, this fiery tower has been incinerating the sewage sludge flowing in from Palo Alto, Stanford University and surrounding cities. It is the final pit stop for the sludge after a long and circuitous treatment process that begins with the flush of a toilet and ends with a truck full of ash making its weekly trip from Palo Alto to a landfill in Kettleman City, more than 100 miles away.
The incinerators -- there are two at the Regional Water Quality Control Plant -- are by far the most unpopular component of the sprawling campus. When they were built in 1969, the sludge-burning towers were widely viewed as a vital upgrade to the former practice of burying waste in landfills. But while their function hasn't changed, their reputation has been steadily plummeting. Today, as the City of Palo Alto boasts about myriad clean-energy initiatives -- from an electricity portfolio that's carbon neutral to environmentally beneficial building codes to cutting-edge laws preparing the city for the electric-vehicle revolution -- the furnaces quietly burn in the background, releasing more than 20,000 metric tons of carbon dioxide annually, according to a 2009 analysis by a specially appointed citizens task force. For local environmentalists, including members of the City Council, it is the antithesis of everything for which the city otherwise stands.
"It's the biggest single source of greenhouse gases in the city," former Palo Alto Mayor Peter Drekmeier told the Weekly.
Drekmeier has long advocated for a new sewage facility that would create energy, rather than just smoke and ash, from the so-called biosolids. The incinerators are near the end of their useful life and replacing them would be far more expensive than changing to a cleaner technology, he has said.
The dislike of the incinerators is nothing new, either.
"For us to be burning our biosolids is terrible," Jonathan Foster, then-vice chair of the city's Utilities Advisory Commission, said in 2011 as the group was discussing a proposed plant that would convert waste into energy. "It's expensive, and the contributions to the environment couldn't possibly be worse. We should send a message to the City Council that we should absolutely move forward in the direction that would lead to the closure of the incinerator."
Even Emily Renzel, a former councilwoman and a leading conservationist who opposes building a waste-to-energy facility in the Baylands, has no reservations when it comes to retiring the incinerators.
"It's the biggest dollars, the biggest energy spent, the biggest polluter," Renzel said. Getting rid of them, she told the Weekly, is "the biggest and most important decision" in the city's future handling of its waste.
Unity against the sludge burners provides a singular point of agreement in an otherwise raging civic debate over the city's grand vision for organic waste.
A strong contingent of the environmentalist community, those who agree with Drekmeier, thinks a new plant should be built in the Baylands to turn sludge, food scraps and possibly yard trimmings into energy. In 2011, the group successfully spearheaded Measure E, which "undedicated" a 10-acre portion of the Baylands' Byxbee Park for this purpose.
Others, from Renzel's conservationist camp, strongly oppose this plan, saying that parkland should not be used for a new industrial waste operation.
But on the issue of biosolids, there is little debate, despite the fact that the effort of upgrading the treatment plant will take years, cost tens of millions of dollars and lead to years of rising wastewater bills for residents of Palo Alto and partner cities.
The City Council, which is as divided as the community on the issue of organic-waste composting and yet united on the issue of incinerators, took a big step last month toward finally putting the burners to bed. On May 12, the council voted to adopt an ambitious multi-year plan that will cost about $85 million dollars to implement and that establishes as a top priority the retirement of the incinerators. Once done, Palo Alto will no longer be one of only two cities in the state that still relies on the sludge burners (Central Contra Costa Sanitary District is the other).
In approving what is now called the Organics Facilities Plan, the council authorized Public Works staff to begin design work for a facility where the sludge would be dehydrated (also known as "dewatered") and prepared for hauling away. The new, $12 million facility would allow the city to decommission the incinerators and begin shipping its sludge to another waste center, most likely the East Bay Municipal Utility District.
Roughly $200 million in other renovations are eyed for the wastewater treatment plant over the next decade. To fund improvements, the city plans to seek grants and bonds. But ratepayers in Palo Alto and its partner agencies will also have to help foot the bill. The latest city forecasts show sewage rates (which in Palo Alto currently add up to about $29 on an average monthly residential bill) rising by 7 percent in 2016 after years of remaining flat. Further 7 percent increases are projected for 2017, 2018 and 2019.
The pending retirement of the incinerators and questions over what will replace them are but recurring refrains in a conversation that began at the city's inception. For Palo Alto's earliest residents, sewage was neither out of sight nor out of mind.
Just after its incorporation in 1894, the city began planning its first sewer network, which was funded by a $28,000 bond in 1898 and constructed the following year. The system included 60 miles of sewers, served about 3,000 people and discharged raw sewage from a 12-inch pipe at the edge of south San Francisco Bay, according to the city's Long Range Facilities Plan for the treatment plant.
By the 1920s, with the city growing and new park improvements planned for the Baylands, officials began to rethink their strategy of dumping solid waste into the Bay. Health officials feared the consequences of the raw sewage on park visitors and boaters at the new yacht club. Furthermore, high tides pushed sewage out of the manholes and onto the city streets, complicating the city's and Stanford's expansion plans.
By the end of the decade, the city began planning for a treatment plant, one of the first in the San Francisco Bay Area. It began operations in 1934 and had the capacity of 3 million gallons a day. It discharged the effluent 700 feet offshore, according to the long-range plan, and treated raw sewage through anaerobic digestion (a forefather to the technology that the city is now considering, which uses bacteria in an oxygen-deprived atmosphere to process organic waste and release methane, which is then converted to biogas).
As the city's population grew, the plant underwent a series of expansions, its capacity doubling by 1956. Yet even with these improvements, "It became apparent by the late '60s that the plant would soon be overloaded again," wrote Ward Winslow in "Palo Alto: A Centennial History." Industry was on the rise, and the city's area roughly doubled, overwhelming parts of the sewer system.
With the state adding new water-quality regulations, Palo Alto, Los Altos and Mountain View agreed to build a new wastewater-treatment plant, a facility that would also process wastewater from Stanford, Los Altos Hills, the East Palo Alto Sanitary District and (before its annexation by Palo Alto) Barron Park.
Winslow calls the 1968 facility a "state-of-the-art plant" and notes that the city had even made money from gold, silver and other precious metals that were recovered from the sludge.
The incinerators that came online appeared to solve a number of problems at the time, according to Jaime Allen, the current plant manager.
The burgeoning electronics industry was sending many heavy metals to the plant, which were disrupting the anaerobic digesters. One alternative, trucking out the sludge, "smelled really bad," he said.
But incineration could handle the metals, didn't smell so much and would lessen the impact of the resulting wastewater on the Bay.
"It didn't need much land and energy prices were quite low at the time," he said.
The sewer system, meanwhile, continued to gradually expand and today encompasses about 217 miles, according to a recent financial forecast from the city.
Now, form follows function at the Regional Water Quality Control Plant, a 25-acre industrial campus that somehow remains hidden in a city that is often referred to as "built out." The structures housing the incinerators and the wastewater pools are set far enough off from Embarcadero that a passing driver may not even realize that just yards away stands an industrial plant that treats 100,000 gallons of sludge daily.
It's really easy not to think about the plant.
"When you flush, it's out of sight and out of mind," Allen said during a recent tour of the facility.
Despite their notoriety, the two incinerators take up only a small portion of a campus filled with tanks, pumps and testing laboratories. The first line of defense is the "grit room," a malodorous enclosure in the middle of the campus where rags, plastic bags and other forms of debris are removed by bar screens from the stream of waste entering the plant. From there, the wastewater is pumped into four "primary sedimentation tanks," each of which is 220 feet long, 40 feet wide and 11 feet deep. This is where grit is removed from the wastewater and where solid sludge is separated out and sent to three "sludge thickeners."
The wastewater then flows through different stations where nature and engineering combine to remove unwanted organics from the stream before it flows into the Bay. In the first tower, water cascades over a plastic, herringbone-patterned filter that's covered with oxygen-eating bacteria. The filter consists of about 8.5 million square feet of plastic, Allen said.
"If you stretch it out, it would cover about 1 percent of Palo Alto," he said.
Next to this filter stand four green and bubbly lagoons where Mother Nature does most of the work. The microbes in this giant "aeration basin" convert ammonia and other organics in the water into heavy biomass that falls to the bottom.
In the next pool over, a boisterous flock of seagulls happens to congregate in another sprawling wastewater pool to feast on the microscopic worms that in turn feast on the effluent bacteria.
From there, the wastewater proceeds through filters of sand and charcoal and undergoes ultraviolet disinfection before it splashes into the Bay. The lattermost process is relatively new at the plant, having been installed in 2010 as a response to increasingly stringent water-quality regulations.
The extensive wastewater-treatment process looks and feels relatively modern. The odor is tolerable around the pools, despite the never-ending stream of wastewater flowing through the pipes and pools. It is manned by 72 employees and monitored 24/7 on 23 flat screens displaying information about water flows, oxygen levels, pollution emissions and energy use, along with other data. On a recent afternoon, one screen showed the amount of wastewater flowing into the plant from each of the partner agencies. Mountain View was slightly ahead of Palo Alto, with other partners lagging far behind.
"Peak flow is halftime on Super Bowl Sunday," Public Works Director Mike Sartor said during a tour of the operations building. "That's kind of the legend. You have to be able to handle the halftime of the Super Bowl."
Allen said the wastewater plant processes about 23 million gallons of wastewater a day. The peak flow is around noon, when the rate is closer to 30 million. In the early morning hours, before the showers start running, the amount drops to about 10 million gallons. The constant monitoring and testing give the plant the feel of a high-tech facility that cannot fail.
The same cannot be said of the final step for treating solid waste -- incineration -- which is plagued by rust, corrosion, a foul odor and a dismal reputation. The two incinerators are housed in cylindrical towers, each of which consists of stacked hearths. After the dewatered sludge comes in through the top of the furnace, it passes down through three zones: the drying zone at the top, the combustion zone in the middle and the cooling zone at the bottom. When sludge reaches the middle zone, air and natural gas are added to the hearths, raising operating temperatures to up to 930 degrees Celsius (1,706 Fahrenheit), according to the plant's Long Range Facilities Plan.
The process reduces the volume of sludge by a ratio of 20 to 1. It takes only about one truck per week to haul the ash. Without the burning, it would take four trucks a day, Allen said.
When asked about the council's recent decision to revamp the sludge operation, Sartor and Allen noted that the existing incinerators are old, that replacing them would be extremely costly and that they are having a hard time meeting the federal government's increasingly stringent air-quality requirements. The process also isn't very energy efficient.
"Our treatment plant is the highest, single-most intense fuel-use of any city facility by orders of magnitude," Sartor said.
In addition to the pollution and energy consumption, the incinerators also face questions over seismic safety. In 2012, the city completed an assessment of the entire wastewater plant to see which components need to be replaced and when. The Long Range Facilities Plan, which was put together by the firm Corolla Engineers, concluded that while the furnaces are unlikely to collapse in the event of an earthquake, they would suffer interior damage.
If things go as outlined in the new Organics Facilities Plan, the incinerators would flicker for the final time in 2018, capping a half century of critical but often thankless service.
Then the sludge would be trucked to either the Synagro facility in Merced County or the EBMUD anaerobic-digestion plant in Oakland as an interim solution while the city's long-range, big-ticket item -- a wet anaerobic digester -- is being designed and constructed. The new dewatering and truck off-hauling facility would be completed prior to the incinerators' retirement. Staff estimates that demolishing the incinerators will reduce 2,343 annual tons of greenhouse-gas emissions and open up about half an acre on the campus for construction of the new anaerobic digester.
Even so, it's not exactly a cause for celebration.
"The dewatering facility is essentially an insurance policy," Drekmeier told the Weekly, referring to it as a long-term backup to the digester. "No one really gets excited about insurance policies until they're needed."
The anaerobic digester, according to staff's most recent timeline, would be in place by 2021.
Before the new anaerobic digester is built, the city still has to work out numerous crucial details, not the least of which are financing and the ownership model. Public Works initially recommended having a private company operate the new plant. Now, staff is leaning toward having it be a city-owned facility.
Palo Alto will also have to convince its partners to support and help pay for the wet anaerobic digester. Assistant Public Works Director Phil Bobel told the council on May 12 that the other cities will be on board when it comes to replacing incinerators and treating sludge in a new energy-generating plant. Composting food scraps, however, might be another, more technologically complicated, matter.
"We know on the sewage part of it we'll have the five other partners in the treatment plant, but on the food side we don't know if we have any," Bobel said. "We'll have to work that out."
The partnering cities have been receiving updates, Bobel said, but are not expected to take any action on the organics plan until after Palo Alto moves ahead with the new plant.
So far, not everyone is convinced that anaerobic digestion is the way to go. Dennis Scherzer, a board member at the East Palo Alto Sanitation District, is among the skeptics. At the April 29 meeting of the City Council, he urged Palo Alto officials not to pursue an anaerobic digester and to instead consider other "tried and true" technologies such as gasification, which uses heat and oxygen and/or steam, and pyrolysis, which uses heat.
"I will not be voting to support an anaerobic digester," Scherzer said.
Under the city's timeline, staff will hold meetings with its partner cities this year and next and develop financing plans for the new sewage facilities by March 2015. Once the dewatering and haul-out facility are completed, the incinerators would be demolished. This means that in the next five years, the way in which Palo Alto treats its sewage will undergo its most significant transformation in nearly half a century.
Until then, the wastewater dilemma promises to be the most benign component of a conversation that remains deeply contentious. On May 12, proponents of a local waste-to-energy facility scored a victory of sorts when the council directed staff to move faster on the composting piece of the organic-waste puzzle. The council asked Public Works to immediately issue a request for proposals for composting and to give preference to the Measure E site (of which, officials now believe, only 3.8 acres would actually be needed). Councilwoman Karen Holman was one of two members who dissented, along with Greg Schmid, and sided with the conservationist camp that advocated holding off on composting decisions. But when it comes to sewage, she was as bullish as anyone.
"Let's get going with the wastewater, the incinerator -- that's a huge polluter. Let's get going now," Holman said. "We can address the composting issue as new technologies emerge and we adopt composting on-site at-home solutions."
Mayor Nancy Shepherd, who unlike Holman supports a composting facility in the Baylands, likened it to the city's prior game-changing decisions such as the installation of a dark fiber ring, a move that she said "paid off spectacularly in ways we can't see." Shepherd said she will cast her vote "enthusiastically," even as she acknowledged that the topic isn't as sexy as Palo Alto's other technological breakthroughs.
"I get to talk about sewage sludge with my friends and how not to incinerate it and how to be responsible and continue to push the envelope of responsibility, even if it's not pretty to do," Shepherd said.