News and Features

home | metro silicon valley index | features | silicon valley | feature story


The Ultimate Download

San Jose's sewage plant is a wonder of old-school science and technology. And it's falling apart.

By Alastair Bland
Photographs by Felipe Buitrago

THE COLLECTIVE habits and trends of South Bay society are easily apparent at the San Jose–Santa Clara Water Pollution Control Plant. For example, employees there have noticed that baby wipes have become popular in recent years. Locals, too, have evidently eased up on dietary corn in the past decade—at least the whole-kernel variety. From May through September, carbon coalesces as oily black grit on the surface of the slow-moving settling ponds. It's the undigested residue of overcooked meat and summertime barbecues.

Longtime plant workers have witnessed changes related to the area's economy. Before the fruit-canning industry left town in 2000, the sewage plant's water intake periodically grew syrupy, as tons of peaches, plums, cherries and pears underwent processing just up-current. And trace heavy metals became a substantial problem in the early 1990s as the tech industry grew.

Workers at the plant tell an interesting sports story: As the Super Bowl draws toward the end of the second quarter, plant operators know it's coming. An hour into the game, the water flow begins to increase. And as the victors take to the press room—and as Santa Clara County unseats itself from couches countywide—the phenomenon arrives in full force. The dark brown current swells perceptibly until the volume has increased by a full 10 million gallons—but it only lasts an hour. And just as suddenly and just as predictably, the waters subside again. It happens every year. They call it "the halftime flush."

But most of what comes down the pipe at the plant is, frankly, shit. The 53-year-old facility, which occupies 2,600 acres of former marshland on the southern shore of San Francisco Bay, serves eight cities and receives the toilet flushings of some 1.4 million people.

An average rate of more than 100 million gallons of water enters every day, guided through a conceptually simple yet technologically advanced system of screens, filters, microbial cleansers and digesters. The water is black as a swamp when it enters, but not 24 hours after each flush arrives, it rushes out again, clear as tap water and just about as clean.

The water flows into a large wildlife sanctuary—the Don Edwards San Francisco Bay National Wildlife Refuge—and here birds thrive and fish sometimes swarm. Meanwhile, a 600-acre grid of levee-lined ponds is reserved for the fecal matter itself, which spends several years drying in the sun. By the time it's 90 percent dehydrated, it is Class A stuff—the good shit. This means that trace toxins are so scant that it could legally be used as farm fertilizer. But with few growers nearby and Newby Island Landfill just across Los Esteros Road, the crumbly detritus is gifted to the dump managers, who use it to cover their trash heaps.

The entire treatment process, from start to finish, illustrates the leaps and bounds by which society has improved its own hygiene in the past half-century, to say nothing of the past 500 years. But there's still room to improve, and today the sewage facility is looking at a massive makeover.

Billed as the "Plant Master Plan," the project aims to correct five decades of infrastructural decay as well as advance the system into an ambitious program of 100 percent energy self-sufficiency and zero-waste operations.

The project could also prevent an ecological disaster. As inflow volume increases with the South Bay's growing population, the chances that the facility will someday experience a devastating overflow are growing more likely.

The last near-disaster was in February 1998. After several weeks of torrential rains, a surge of rainwater leaked into the sewage lines and flooded down the pipes faster than it could flow through the four entrance screens at the head works, where the county's wastewater first enters the plant.

To imagine the excitement of what followed, picture yourself flushing a toilet—a toilet in a public space, like a restaurant. Now, imagine that the toilet water does not drop, and that it appears to be clogged. The dirty water rises, slowly, yet fast enough to incite rapid panic. You whirl about, looking for a plunger. There isn't one, and you next wonder if you'd dare dunk your hand through the mire to free the clogged sludge, but before you can work up the nerve, the evil water has risen to the rim, where it seems to hang for a terrible moment.

Multiply this minor disaster by a million times, and you've got the picture of the 1998 event.

Fortunately, the levee that surrounds the treatment plant kept the waste from escaping outward into the marshland. But the incident served as a wakeup call and sparked the decision to build a second headworks adjacent to the old. This addition is now fully built and in experimental use, but still other changes must be made as the population grows and as the plant begins to show its age.

The electrical system is wearing out, and the concrete walls are wearing thin. A consulting firm hired in 2007 to diagnose the sewage plant's ailments came up with a grim figure; no less than $1 billion is needed to put the facility in top-notch working order, and that leaves plant managers face to face with one of the greatest logistical challenges faced by engineers today: to seamlessly swap pipelines and tanks in a massive sewage system that cannot be halted, ever—24 hours a day, seven days a week, every day of the year.


GETTING INTO HIS WORK: Engineman Joel Ochoa works on the interior of a motor that blows air into wastewater—one of the primary steps in treatment.

A Sullied Past

Prior to 1956, all the vile bodily wastes of roughly a half-million locals flowed directly into the south end of San Francisco Bay. Not so much as a screening system separated the bay's waters from the community's garbage and sewage—not to mention occasional doses of typhoid, cholera and hepatitis that surely passed through.

The 20-odd fruit canneries that operated locally in the 1940s screened their own outflow to keep organic waste from reaching the bay and sparking the sort of microbial activity that expends all available oxygen in an ecosystem, but during World War II these operations removed the barriers to facilitate outflow and allow for a faster rate of production.

The accumulation of organic refuse in the South Bay destroyed what had been until the early 1900s a favored marshland for clammers, fishermen, duck hunters and naturalists in general. The horrific odors steered visitors away, while the scum and slime that washed in and out with the tides made life a misery and a hazard for residents of Alviso, who lived in constant risk of contracting mosquito-borne diseases.

In San Jose, many residents were blissfully ignorant of the problems downstream, and for several years the populace resisted a proposal to increase utility rates to fund construction of a sewage-treatment program.

But in 1956, the wheels of progress began to roll. The city installed a screen at the sewage outflow. It didn't change much, though; the problems of microbial pollution and oxygen depletion persisted, and only the big solids, like dead cats, condoms, hair clods, scrap metal, lumber and other refuse, were kept from the bay. The system was essentially still as archaic as anything to be found then or now in the Third World.

In 1964, city planners installed the secondary treatment stage, in which the swamp-black water moved slowly through a series of settling ponds as heavier solids dropped out and floating matter was skimmed from the top. The remainder—things both mushy and microscopic—still drained into the bay.

Finally, in 1979, the biological treatment stage was implemented. This is where the real magic happens in a process that mimics exactly what happens naturally in any stream or aerated body of water, only in a highly accelerated and intensified way.

A steady stream of screened sewage enters a series of cement basins, each 20 feet deep, about as wide, 100 yards long and churned from below by air jets. Here, microorganisms cultivated precisely for the job latch onto the swirling debris and particulates from humans and from soaps, detergents and various pollutants—and they feast, breaking down the corruptions of our digestive tracts.

These bugs and the waste they produce meanwhile clump together into a coagulated gunk of microbes and grit called floc. The water is ushered into circular swimming-pool-like basins, flanked by olive trees, where the heavy floc precipitates out. The material is later dredged from the bottom, most of it sent to the three-story-high anaerobic digesters, and the rest is streamed back into the aerated basins, roiling nonstop with the endless flow of sewage created by 1.5 million residents of a 300-square mile area encompassing San Jose, Santa Clara, Milpitas, Campbell, Cupertino, Los Gatos, Saratoga, and Monte Sereno.

The sludge is pumped out of the digesters, which cook methane out of the waste, and the brown mush moves onward to the drying ponds on the property's east side, just a friendly wave from the residents of Milpitas. Each pond contains sludge in its own respective stage of dehydration; some ponds are still layered with 2 feet of water, fresh from the digesters, while others, three years into the process, are caked with detritus as crumbly as pie crust.

Meanwhile, the hazy water enters its last stage of treatment: filtration. It is drizzled through 2 feet of coal and a foot of sand, finishing its 20-hour circuit through the facility as clear as tap water and almost clean enough to drink.

The treated water flows northward and by gravity for the last quarter-mile of its journey. Once polluted with industrial toxins and human filth, it now meets the open water of San Francisco Bay as pure as many natural streams that flow to the sea.

A footbridge crosses the 30-foot-wide current of water at the property boundary. Just upstream of the bridge, steep banks of earth and vegetation meet the water in a scene resembling that of an Irish trout stream. Just downstream, in a pool of whitewater below a 3-foot drop, sea lions sometimes appear. Gulls stand on the shore. Striped bass occasionally swirl under the surface.

A handful of employees once spent their lunch breaks casting plugs for the stripers. The fishing was excellent, remembers Dale Ihrke, the plant's manager of 19 years, but he had to impose a no-fishing-during-lunch policy about a decade ago when enthusiasm for bass fishing began to distract workers from their duties.

But among this vibrancy of life at the outflow, of human waste in the water there is, miraculously, none.


GARBAGE IN, NO GARBAGE OUT: After the final steps of purification, the water that flows into San Francisco Bay is relatively clean.

The Dirty Work

Mike Ortega has worked at the plant since 1980. He recalls his shifts at the headworks almost in a reverie. One day, he says, the ditched spoils of a bank robbery came piling up against the five-eighths-inch screens.

"It was like, 'There's a hundred, and there's another!' It wasn't enough money that we could have run off with sacks of it, but it was still obvious that something had happened."

They reported the incident to the police.

Ortega also remembers when Del Monte still fed its fruit trimmings into the sewage stream. The apple cores and such turned up around the property. Sometimes the fruit fermented.

"Seagulls ate it," recounts Ortega. "We'd watch them get drunk off the stuff."

And several decades ago, according to Ortega, patches of feral marijuana appeared on the premises. It was before his time, and no one employed at the plant today knows for certain the details, but it is believed that the phenomenon came as a result of the once-commonplace trend of smoking seeded marijuana. Presumably, the ash from butts and pipes went down the toilet with the occasional unburned seed. At the plant, these were screened out of the water—meaning the weed must have grown post-1964—and eventually shuttled with the sludge to the drying ponds, where they could only have thrived in the highly fertile conditions.

But that's all water under the bridge. Today, Ortega enjoys the rather plush comforts of employment in the computer control chamber, a quiet room just down the hall from the front desk. Among Ortega's duties is the task of eyeing 32 screens presenting real-time figures on water inflow and outflow, current stability, digester temperature and other critical parameters.

Elsewhere in the sewage plant, sophisticated technology is pitted against the things that could go wrong. In a mazelike series of laboratory chambers, men and women in white coats and protective eyewear analyze samples drawn from varying stages of the treatment process. Some look for trace heavy metals. Others, like Kingsley Okeke, a microbiologist of 20 years at the plant, spend a good deal of each day watching microbial activity on a flat-screen magnified thousands of times.

Clumps of tiny creatures occupy most of the screen, while scattered debris lies strewn elsewhere. "Free-swimmers"—microbes that have not yet clumped into the mass of critters and feces—twitter about the screen, bouncing soundlessly off of obstacles like a ping-pong ball. Filament arms flail about from the seething mass, like octopi seeking playthings.

A graphic chart of illustrations on the wall behind them depicts all the common suspects to be found in such a biological soup, and Okeke and his lab partner, chemist Jon Dixon, regularly try and match onscreen living microbes to their illustrated counterparts on the wall.

They must, in fact, identify every microbe that shows up in the samples drawn from the roiling biotreatment tanks, for part of their job is to attain optimal population levels of each microorganism, a fine-tuning task that never ends as they adjust aeration, filtration and anaerobic conditions in the tanks to keep the ecosystem in balance.

But there will always be unwanted microbes. Samples collected from the plant's outflow stream sit on the desk in sealed Petri dishes.

"There's Enterococci in that one," says Okeke, pointing. "That one will ruin your day."

He points to another containing Enterobacteriaceae, the microbe that causes such gastrointestinal nuisances as Montezuma's revenge. E. coli, too, appears occasionally in the outflow. The fact is, even after filtration, chlorination and removal of the chlorine with sulfur dioxide, there is no way to remove from the treated water every trace of organic evils, which the plant can detect at a boggling parts-per-quadrillion level.

Less dangerous than those microbes and more of a simple hassle is Nocardia—the plant is still recovering from a wintertime infestation. This genus of annoying microbes does everything that a sewage treatment plant could want in a microscopic creature, except one: sink. While the desired bugs gobble up particulates, then coagulate and precipitate to the bottom of the clarifying pools, Nocardia floats. During the height of the infestation in February, a lattelike foam 3 feet thick covered several of the pools.

Lab manager Dave Tucker, on the job since 1988, says that Nocardia invades the biological tanks regularly during rainy weather. Nocardia is a soil-based bug, and when storm waters leak into the sewage pipes upstream, there's only one place it can go: the plant. Today, small patches of the gray-brown foam still collect on top of the roiling biological treatment pools, remnants of the dying Nocardia population, but the plant is in full functioning order again.

Another of the everlasting concerns at the plant—and a primary reason for the 24/7 eyeballing of the operation—is that a chemical spill upstream, intentional or otherwise, might inundate the system and, in the worst-case scenario, kill the microbes that the facility cultivates by the trillions in the clarifying tanks for the job of removing particulates and pathogens from the water. In such a situation, the untreated sewage simply flows into the bay. A scare came in 2002 when a surge of red water entered the headworks.

"We thought it might have been a diesel spill," says Ihrke.

It turns out that a small box manufacturer in Santa Clara had a messy chemical spill in the basement. The manager of the business panicked and washed the volatile stuff straight down the drain, skipping a routine treatment step—but at the San Jose sewage plant the heroic microorganisms were waiting with their mouths open for the waste, and they dealt with it.

But the real deal—what Tucker calls a plant manager's "worst nightmare"—occurred in September 1979. Operations failed, and between 2 billion and 4 billion gallons of untreated water ran into the bay over a three-week period.

"The valley was different then," he says. "There were a lot of canneries, and during part of the year they canned a lot of fruits and vegetables. One time, they overloaded the system with their discharge."

The microcritters in their surging, aerated basins were thrilled for a while. They feasted on sugars and protein and other good stuff that the plant had never seen before. But bacteria know no limits on indulgence. Almost limitless organic matter came down the pipe, and the bugs overate.

"You feed them too much, and they'll eat themselves to death," says Tucker.

To be exact, the microorganisms ate so fast that the air jets couldn't supply enough oxygen to keep pace. The bugs used up all the oxygen, then suffocated. The facility essentially died, and between Sept. 6 and Sept. 28 at least 100 million gallons of waste daily streamed into the bay, as nasty as the hour it was flushed.

But worse than simply filling a public waterway with raw sewage, such spills lead to oxygen depletion in the ecosystem, in much the same way that the phenomenon occurred in the sewage plant's treatment tanks that September.

By the 13th of the month, just a week after the spill began, commercial fishermen (yep; they still had jobs back then) were reporting an absence of fish and shellfish in the south end of the bay. Full treatment was resumed on Sept. 28, and by Oct. 18 fish began to reappear in the area.

Such events are rare. They are nasty. They are highly frowned upon by everyone from the most qualified chemist to EPA agents to the most ignorant layperson who has just the faintest idea of what goes on at a sewage plant; for raw sewage entering the water is a fairly simple concept to understand.

Such events are illegal, too, and it may seem a bit unfair that the plant receives not only the community's shit but also the responsibility of dealing with it. Then again, the community funds the plant and pays its workers through utility fees—so they'd darn well better do their job. And the plant has incentives to do so; fines for violating federal and state water pollution regulations can max out at $37,000 per day, and state inspectors regularly visit to see what's coming into the plant, and what, exactly, is going out. The good news is that the plant's outflow is some of the very cleanest treated sewage water in the nation and the cleanest entering the bay.


CLEAN ROOM:Plant manager Dale Ihrke works in the main control office, which resembles a submarine control room.

Something Stinks

To prevent—or at least keep track of—toxic or otherwise problematic discharges, a team of 45 city inspectors in the pre-treatment sector communicates daily with businesses upstream, of which there are about 350 that contribute to the wastewater stream.

The pre-treatment team keeps informed on what each establishment is up to, what they're releasing into the water and how much. Part of acquiring a business license, in fact, includes having a chat with the pre-treatment team and promising to conduct dilution measures before sending volatiles down the drain and to keep some things out entirely. But even the most well-intentioned commercial operations goof up sometimes.

Several years ago, staff observed the abrupt appearance of thousands of confetti-size plastic shreds entering with the inflow at the headworks. Much of the waste was fine enough that it escaped through the screens. Unpalatable to the microorganisms in the biological stage, unsuitable as fodder for the digesters and illegal for the treatment plant to discharge into the bay, the plastic posed a logistical headache as the pre-treatment department hurried around town to check on the most likely suspects. It turned out to be a nonmalicious case of a local plastics recycler accidentally allowing some of its product into the sewer lines.

But two cases of illicit dumping by metal-plating companies are currently in the courts. One is a civil case in which the factory managers decided to bypass the required routine treatment and dilution processes and pour their cyanide and copper waste directly into the sink.

The manager did so in the middle of the night, but little did he know that pre-treatment agents had, as part of their surveillance program, recently slipped an automatic sampler into the pipe just down the block. In this process, inspectors dangle a heavy plastic drum into a manhole, often under the cover of night or on weekends.

From this apparatus runs a hose that leads into the sewer pipe. Fixed to the drum is an automated pump, which pulls samples from the sewer at intervals—often once per hour. Each sample is deposited into its own receptacle in the belly of the drum, and subsequent analysis in the sewage plant's lab reveals to technicians just when certain contaminant levels peaked.

"We saw the metal levels shooting up at between 1 and 5 in the morning," recounts John Mukhar, a senior engineer with the city's Environmental Services department, which conducts pre-treatment work for the sewage plant. The late-night anomaly was a clear sign that someone was up to no good. So the pre-treatment team considered the arrangement of the pipes and the various businesses upstream of the contaminated samples, and inspectors quickly zeroed in on the suspected offender. Now the little company is looking at a $1.4 million settlement with the city and county of San Jose.

The other case is in the criminal courts. Copper, nickel and zinc were knowingly being let into the sewage system. Again, the dumping took place at odd hours of the night.

"They just thought that it would be a safe time of day," says Mukhar. "They just thought, 'It's late, no one's around, no one will notice.'"

Wrong. Pre-treatment had recently placed an automatic sampler just down the block. Rapid lab analysis of the samples left little doubt of the culprit's identity, and inspectors even managed to photograph employees dumping chemicals straight down the drain.

Winds of Change

When the afternoon breeze blows, residents of Milpitas occasionally are reminded that they live less than a mile from the Bay Area's largest sewage treatment plant. Odor complaints arrive at the front desk from time to time, though as often as not the nearby landfills are to blame. But as the Plant Master Plan gains momentum, plant manager Ihrke and a team of technicians and engineers are looking at ways to be a better neighbor.

Buffer acreage already separates the plant from nearby residents—from sight, if not from smell. This open land was once farmed, but today it sits fallow. A mower used to come in routinely to cut the grass, but the cost for a mere trim ran to 25 grand. Even before that, a disker did the work, chopping up the soil periodically, until the city of San Jose mandated a stop to all activity that threatened burrowing owls, which thrive on the property and cull the rodents.

And so the job of grass trimming is now the responsibility of 2,000 sheep and goats. They live on the premises, a herd lent to the plant by Living Systems Land Management, a San Francisco grazing service. For the animals, there could be no better use of a 1,000-acre field, but the city of San Jose sees the buffer land as one of neglected potential.

Officials now hope to boot the grazers and open up the fields to other uses. Ideas are being discussed at City Hall. One proposition would turn the area into public parkland or soccer fields. Another (and one which would generate revenue to help offset the Master Plan's $1 billion price tag) is to lease the land to renewable technology companies while staying mindful to the needs of the resident owls. Otherwise, increased user rates will cover costs.

Meanwhile, the city hopes to reduce the 600-acre sludge-drying ponds to just 100 acres. A greenhouse sun-baking system could do the trick while also shortening the time required for drying. The system would enclose the vicious aromatics and grant a breath of fresh air to the patient residents of Milpitas.

On-site solar generators, too, could fill the plant's need for energy, which is tremendous. The plant uses more energy, in fact, than the rest of San Jose, and while gravity provides much of the force needed to move the water and sludge through the system, the elevation discrepancy between your toilet and the treatment plant is so slight that this natural force alone cannot complete the job.

So engines and pumps are employed. Methane is burned to run them, and in a place like this there is no shortage of the odorless gas. The methane is drawn off the top of the digesters and piped directly into use. The plant also captures the methane produced by the landfill next door, and at the end of the equation, just one-third of the plant's energy needs are drawn off the grid. But the plant hopes to go off-grid within five years, remaining attached only via a backup power line for emergencies.

Zero-waste ambitions also inspire the dreams of the plant's operators. Dried sludge could be incinerated as a fuel source. Fat, oil and grease could also be skimmed off the settling ponds for use as biofuel. And as much as half of the sewage plant's outflow could easily be diverted to fulfill the community's irrigation needs. With so much room for streamlining the efficiency of the plant, the notion becomes clear: Sewage is not waste but a resource.

The general public even seems to be gaining an interest in the stuff. Not only do aspiring chemists, microbiologists, engineers and others actually follow career paths that lead directly into sewage treatment plants, but tourists also flock here. Last summer, staff at the San Jose–Santa Clara Water Pollution Control Plant proudly led 4,000 visitors through the facility to have a close look at its inner bowels, to marvel at their very own toilet water coming in at the headworks and to watch it exit at the outflow, as clear as air and cleaner than any other treated sewage water in the Bay Area.

Ducks paddle about the stream. Marsh rodents work the banks. Burrowing owls pop up to say hello. And they all drink the water.

Send a letter to the editor about this story.