Will the stars from heaven descend?
Can the earth-worm soar and rise?
—A.L. GORDON, Ashtaroth: A Dramatic Lyric, 1867
I CAN’T DECIDE if this is the ultimate insult to an earthworm or its highest calling, but it has been suggested that worms may be perfectly suited to play an even more intimate role in the lives of humans—that is, to help process sewage.
Bruce Eastman, a manager at the Orange County Environmental Protection Division in Florida, began working on a way to use earthworms to treat human sewage. He knew that worms, through their digestion, killed some microbes and encouraged others to flourish. It seemed plausible that worms could work their way through sewage, digesting harmful bacteria and shifting the microorganism population around so that the end product was safe for plants and even food crops. When I first heard about the idea, I had the same reaction that most people probably would have: I was repulsed by the idea of using human waste in my garden, even after earthworms had digested it. But then I thought about the bags of manure that I’ve hauled home from the nursery over the years. What’s the difference? If earthworms could make sewage safe, if they could turn it into vermicompost, why not use it in the garden?
When Eastman began his research in 1997, only a handful of sewage treatment plants in Florida were able to produce what the EPA calls class A biosolids, or sewage sludge that is free of harmful bacteria. Most of the sewage produced in Florida—about two hundred and thirty thousand metric tons at that time—was spread on unused land for want of a better way to get rid of it. Over time, the rules for disposal of this waste have gotten stricter, and sewage treatment plants were facing the possibility of a very expensive retrofit to meet the new requirements. Eastman started to wonder if earthworms could reduce the dangerous pathogens in biosolids—namely salmonella, E. coli, and other gastrointestinal viruses. Experimenting on a test row, he and his colleagues found that the bacteria started to disappear when earthworms were given a chance to eat their way through the sludge. The EPA was interested in the idea and granted Orange County an experimental permit to do a larger study. The goal was to see if earthworms could bring about a three- to fourfold reduction in pathogens, which would be enough to ensure that the sludge was safe for human contact.
The researchers set up long windrows—gently mounded rows —of biosolids at the sewage treatment plant. They measured the levels of pathogens in each row to make sure they were comparable, then added the red wiggler, Eisenia fetida, to half the rows. In just six days, they had their answer: earthworms far exceeded the targets set by the EPA, bringing harmful bacteria down to a level that would earn the biosolids the cleanest rating, class A. Class A biosolids can be safely applied to land for all kinds of agricultural uses (one of the EPA’s booklets includes a photograph of a flowerbed at Walt Disney World’s Epcot Center that has been enriched with biosolids). Since then, similar results have been achieved in sewage treatment plant studies around the world; in fact, one plant in Korea processes eighty tons of sludge every day in a giant earthworm reactor. Although the EPA has not yet approved a method for earthworm composting of biosolids, the use of some kind of biological process to treat sewage has become increasingly popular, and it seems likely that earthworms may have a role to play in the near future.
YOU MAY NEVER tour a sewage treatment plant yourself; I can’t blame you for that. But when I heard that a worm composting project for biosolids was just getting underway at a new treatment plant in Pacifica, a town just south of San Francisco, I had to see it for myself. My uncle, David Sands, was in charge of a native plant restoration project at the facility, and he’d been asked to head up the worm composting project. One afternoon I put on my oldest clothes—a pair of jeans and a flannel shirt that I would not mind throwing away at the end of the day, if I felt so inclined—and I drove down the coast to take a look.
The Calera Creek Water Recycling Plant is situated off Highway 1 just south of San Francisco. The turnoff is unmarked; it could be any one of a dozen roads leading off the highway, through fields of artichokes or Brussels sprouts, to one of those unspoiled beaches known only to the locals. But when I arrived, I realized that this road was too newly paved to be a local surf hangout. There was a recently striped parking lot to the left with the correct number of disabled-accessible spaces—clearly a city lot. I drove through the gate and up a slight hill and there it was: wilderness. An expanse of chaparral bushes and dry grass. A creek, overgrown with willows, winding to the ocean. Here was the city’s state-of-the-art sewer treatment plant, designed just the way the neighbors wanted it: underground, where it could be neither seen nor smelled. I drove down the hill, where only the employee parking lot and the front offices were visible. Everything else was cut into the hillside or buried underground entirely.
That’s not all that distinguishes the Calera Creek Water Recycling plant from its peers, I found out. No chemicals are used in the processing of the waste: naturally occurring bacteria and ultraviolet light do all the work. The plant’s capacity is flexible. Often it can power down during the day and power up at night, using more energy during off-peak hours, a real boon in California’s ongoing energy crisis. Aboveground, recently planted native plants stabilize the hillside. Clean water flows out of the facility into a restored wetland that is home to great blue herons, San Francisco garter snakes, and California red-legged frogs. Bike and pedestrian paths run to the ocean, where water from the plant is discharged after receiving a final polishing in the wetland. The solids (sludge) emerge from the facility as pathogen-free, class A biosolids that will, if the worm composting project proves successful, be digested by thousands of earthworms and turned into fertilizer. It’s a far cry from the old plant, where hazardous spills into the ocean and numerous safety violations led the state to shut it down.
I wasn’t prepared for how clean and modern the plant would be. I can’t say for certain what image the phrase “sewage treatment plant” conjured up in my mind, but I know I expected a filthy place, damp and foul smelling. I had never stopped to wonder how exactly sewage got cleaned. It was just something I took for granted. Imagine: before the middle of the twentieth century, cities deposited their sewage—untreated except for a pass through a metal grate and possibly a gravel filter—into rivers, lakes, and oceans. And that was progress. When Darwin arrived in London after his voyage on the Beagle, the first central sewers, which would carry sewage away from homes and into waterways, were being installed. Before that, Londoners deposited their waste in cesspits under their homes. The stench was often overpowering, and the levels of bacteria were certainly responsible for the kinds of lingering illnesses from which Darwin suffered. It is hard to believe that such conditions prevailed only 150 years ago. And now, after so much progress, it seems a little ironic that the most modern sewage treatment plants are being built underground, as if we are once again burying our sewage in the domain of earthworms.
When I met Dave Gromm, the plant’s superintendent, I asked him about its name. He laughed and shrugged his shoulders. “Calera Creek Water Recycling Plant? I guess somebody thought it would sound better than ‘sewage treatment plant.’ It’s the same thing, though. It’s still sewage. It’s just what we do with it that’s different.” He’d set aside the afternoon to walk me through the plant and explain its design, which is innovative and unusual: although the various components are in use around the country, no one had ever put them together in quite this way.
Sewage, which includes household waste, some industrial waste, and runoff from storm drains all over town, flows to a pump station where large filters screen out inorganic objects—soda bottles, tennis balls, and anything else that made it down a sink or through the grate of a storm drain—and the pumps move the sewage to the plant, where it fills one of five underground chambers called “sequencing batch reactors,” or SBRs. Putting these SBR tanks underground is what made it possible for the plant to be so well hidden from view. Gromm was careful when he mentioned this key element in the design, which was included to please neighbors living on either side of the plant. “From an operator’s standpoint? It makes the tanks hard to get to. Fiberglass hatches would’ve been nice.” I couldn’t argue with him. If I was in charge of five tanks filled with 1.2 million gallons of raw sewage each, I’d want to be able to see them, too.
On the day of my visit, a quiet Friday afternoon, Gromm took me downstairs to watch the process from a computer terminal. I looked over his shoulder. “Look, this one’s filling now,” he said. “The bacteria have been sitting in the bottom of the tank for a while now, and they’re hungry.” The image on the screen was like a sewage treatment plant operator’s version of a flight simulator. Each part of the system was illustrated by animated schematics: green dots indicated that a chamber was open; a grey mass at the bottom of the tank represented the bacteria.
Once the tank filled, we watched air being pumped in (on the screen, it looked like tiny animated champagne bubbles being pushed into the tank). This creates a reaction with the bacteria that converts ammonia to nitrate. After the air is pumped in, a vigorous mixing turns the nitrate into nitrogen gas, which is then released into a massive air filtration system that prevents any odor from leaving the plant.
The mixing stopped so that the solids could settle to the bottom of the tank. “OK, the bacteria are done eating. This is its quiescent period,” Gromm said, with something that sounded almost like affection. The bacteria did their job in only seventy-five minutes and now the tank sat perfectly still so that the solids could separate from the liquids. “After this, it’ll be ready for the decant. There’s this device that sits just a little below the surface and draws water out. That way it avoids any solids that are still floating on the surface.” From here, the water will be pumped to an ultraviolet-light disinfectant system and the solids are pulled into a holding tank. The whole SBR process takes about five hours, with five tanks in different stages at any given time.
Gromm left his computer terminal and led me through the rest of the plant, most of which is also underground but situated in large rooms where the equipment is accessible. The first room, called “the gallery,” is adjacent to the buried tanks; this is where the sewage is pumped in and pumped back out, and this is also where the massive air filters remove any odor from the air leaving the plant. The filters do such a good job that people working in the front office can’t detect any smell at all.
It stank in the gallery, but it wasn’t as bad as I thought it would be. It was not as foul as the dump on a hot day; it did not even stink as much as the house that my college landlady shared with several dozen cats. The smell inside the gallery was an unpleasant, vaguely organic smell, just a few degrees off from that of a dairy farm. It was just powerful enough to make me glad that all the valves, seals, and pumps were in perfect working order. You wouldn’t want to be here on a day like the one that Gromm described, shouting over the roar of fans and motors.
“This whole thing’s computer controlled,” he said, waving his arm at the equipment all around us. “We had all these glitches when we first got started. The blowers would stay on when the computer said they’d been turned off. Or the filters would clog. The thing is, we’ve got continuous flow here. You can’t just take a filter off line to unclog it.
“One day early on, the computer gave the command to open the influent valve and release the sewage. But what the computer didn’t know was that this key that opens and closes the valves had dropped out of place. It told the system to release the sewage but this valve was still closed and we had sewage”—he paused and rolled his eyes—“everywhere. I don’t know how many times we flooded this parking lot.”
“How’d you ever figure out what caused it?” I asked. We were looking at a fifth of the plant’s computerized equipment, and it filled a room larger than a high school gymnasium. I could see dozens of places where a valve could get stuck or a filter clogged.
He beamed. “I watched it being built. They needed inspectors on the job site so I brought some of my guys down from the old plant and we did the inspections. There’s not a pipe anywhere that I didn’t watch being laid.”
He took me to a large room upstairs where the solids get sent after they leave the SBR. “It gets deposited up here,” he said, pointing to a tank of liquid sludge. “Then it gets sent over to the ATADs.”
ATAD stands for “autothermal thermophilic aerobic digestion.” It’s a process that was developed in Germany and has been used in Europe since the 1970s but has only recently gained popularity in the United States. The EPA classifies sludge coming out of ATADs as class A, thanks to the thermophilic, or heat-loving, bacteria that kill the fecal coliform, the salmonella, and the roundworm eggs by heating it up to 160 degrees.
The smell was worse up here. I was getting a strong urge to wash my hands. Now I understood why the women’s bathroom had two shower stalls and four kinds of disinfectant soap. The facility was clean, but just knowing what was getting pumped through here at the rate of a few million gallons per day could make anyone a compulsive hand washer.
The biosolids spend nine days in the ATADs, working their way from one digester into the next, before they are pumped into a centrifuge machine that extracts more water. The solids leave the centrifuge by means of a chute and are deposited into trucks waiting in a truck bay downstairs.
Gromm took me there next. A couple of guys were using large rakes and shovels to smooth out the biosolids in the open beds of their trucks. “What you’re smelling is ammonia,” he said. “That last little bit of water that comes out of the centrifuge? That’s incredibly high in ammonia. We just feed it back into the system at the starting point, so it goes into the SBRs along with the rest of the sewage. I don’t think we’d counted on all that extra ammonia at first. There’s more ammonia throughout the whole process because of that little bit we add back in. We’re thinking about adding a step where we cool the biosolids back down and let the nitrifiers go to work on them to get the ammonia down, then put it through the centrifuge. The bacteria that eat the ammonia just can’t survive at these higher temperatures.”
Clearly, this is a biological process that requires constant adjusting. Gromm manages a colony of bacteria along with a crew of workers. The guys with the shovels didn’t look too unhappy, considering what they were shoveling. “You know what this stuff is?” Gromm asked me, and I nodded. “Well,” he said matter-of-factly, “it looks like what it is.” The chute opened every few minutes and deposited another black, stinking load into the trucks.
This was the end of the line for the biosolids. It was now a good, clean, class A product that would get trucked to a landfill. The city would rather find a use for the solids and eliminate the nearly $100,000 per year it spends in disposal fees. That’s where the worms come in. But before I went to take a look at the worm composting project, Gromm wanted to show me what happens to the water once it separates from the solids. It’s a good example of the kind of “green” solution that’s possible at a treatment plant like this one.
We walked out of the vehicle bay into the parking lot. Across the lot, a fence surrounded long rows of concrete walls, sunk down into the ground so only the tops were visible. Water poured over each wall. The overall effect was not unlike a water feature in a city park. This, Gromm explained, is the sand filter, where larger particles are removed from the water before it flows to the ultraviolet-light treatment belowground.
Over three million gallons of water pass under the closely spaced ultraviolet lights each day. This process allows coliform to be removed without the use of chlorine. Flow regulators monitor the rate at which water is discharged into the network of irrigation pipes leaving the plant. “You know, there’s good coliform, too,” Gromm said with what I was coming to see as a healthy respect for bacteria. “It’s not all harmful. Some of it helps rivers and streams to survive and hosts all kinds of life. But we take it all out anyway. Sometimes I wish we could only take out the bad stuff and leave everything else.”
Gromm and I made one more stop back inside the plant: a sparkling clean, sunny laboratory—one of the few aboveground rooms—where the water and biosolids are tested for compliance with EPA standards. Beakers on the counter contained water from every step of the process. Gromm held up a beaker of absolutely clear water. “This is the final product,” he said. “The EPA requires that we have ten milligrams per liter or less of suspended solids and BOD (biochemical oxygen demand). Last week, we had one milligram per liter. A couple days ago it was zero. Same thing with ammonia. We’re under one milligram per liter steadily.”
Gromm manages a delicate biological system, one that can be upset by somebody dumping oil or gasoline down a sink, or by a sudden storm pushing excess water into the pipes. The process is extraordinarily complex, but in some ways it is as simple and as natural as what an earthworm does when it works through a compost pile. Without the aid of chemicals, a community of microscopic creatures digests, reproduces, and transforms an organic substance—human waste—into something quite different. Nothing but biosolids and clean water leaves the plant.
THE WATER FLOWS into what most people would agree is the crown jewel of the Calera Creek Water Recycling Plant: a man-made designer wetland that is home to endangered species of birds and amphibians, and a hike and bike trail that draws people to the plant. Building this wetland was more than an enormous landscaping project; it was an attempt to enlist bog plants, snakes, frogs, birds, and insects in the final cleaning—“polishing”—of the water before it flowed into the ocean. It seemed like a perfect complement to the biological processes at work inside the plant. And just as I had come to realize that there was more going on in the soil under my feet, I now saw that more was at work in those low-lying, swampy stretches of coast than I had ever realized. Wetlands do something—they breathe, they clean, and they transform.
The idea of releasing treated wastewater into a wetland is not unique to Pacifica. Several dozen natural or constructed wetlands are in use at sewage treatment plants around the country. Wetlands have proven to be the ideal environment for the discharge of treated wastewater: they act as a sponge to absorb excess runoff, and the marsh plants, microorganisms, and silty soil all filter and polish the water. In fact, wetlands can perform, to some extent, all of the functions of a conventional wastewater treatment plant. By the mid-nineties, the EPA had identified wetlands that do just that, such as the Congaree Bottomland Hardwood Swamp in South Carolina, which carries out all the functions of a $5-million tertiary treatment plant. Now a constructed wetland has become a citizen committee’s dream solution to the problem of discharging treated wastewater, or “recycled water.” It is an acceptable place to send the water—preferable, say, to watering a school playground with it or pumping it through a fountain in the town square, practices that would be entirely safe but unpalatable to most people. With wetlands in the United States vanishing at an alarming rate—about sixty thousand acres per year—cities are all too willing to construct a wild and nearly self-maintaining green space that can receive the discharged water, host endangered wildlife, and accommodate a few bicyclists and bird watchers. Constructing a wetland was a natural choice for Pacifica, and the site, an abandoned rock quarry where Calera Creek once flowed, was begging for a restoration of some kind anyway.
PACIFICA HAD NEVER attempted anything on this scale before. “I had my sewer crew growing native plants for the wetland,” Gromm said sheepishly. “What do they know from plants? That’s when one of my guys went out and found your uncle.”
My uncle David makes a living growing plants that are native to a very specific stretch of coastline just south of San Francisco. “You can’t grow these plants in Fresno and ship them here,” he told me as I took leave of Gromm and joined him for a walk through the wetland area. “You have to grow them right here,” and he pointed to the ground. “You see all those plastic pots above where the SBRs are buried? That’s my nursery. That’s where we grew the plants for the wetland.”
I walked the site for the first time with my uncle in 1998, just after he’d started the job. Public works crews had cleared all the vegetation off the site—about one hundred and ten thousand cubic yards—and excavated the area according to a detailed wetland design plan. Calera Creek had been realigned to flow along its original path. David and his crew had planted over fifty thousand native plants.
Frankly, it didn’t look like much back then. At that time, the treatment plant itself was still under construction. Trucks rumbled up and down the hill and dust was everywhere. The native plants still looked pretty scraggly and only a few wildflowers had emerged from the mixture of straw mulch and seed that had been sprayed on the hillsides. The creek bed had been carefully sculpted to look natural, widening into ponds in a few places and narrowing down to a trickle in others. Bare sticks emerged from the water every few feet; my uncle explained that these were willow branches that would take root over the winter. I was skeptical. They looked like dead sticks to me.
“There’s more going on here than you think,” he insisted. A group of wetlands scientists had used a new system for assessing wetlands that was designed to categorize the wetland by its functions, identify other sites that functioned the same way, and create ways to monitor what was happening over time. “People used to stick plants in the ground and call it a wetland,” one of the consultants on the project told me. “Like it was a kind of glorified gardening. But there’s more to it than that.”
David pulled out a muddy blueprint of the thirty-acre area between the new treatment plant and the sea. The wetland was divided into discrete sections called polygons, with a specific plant list for each. The plant lists were developed after the consultants visited dozens of other wetlands along the coast and made detailed lists of the plants growing there. “Each polygon gets planted with a particular plant community,” he said. We were standing in Polygon 41, Palustrine Forest II, Point Bar. “It’s pretty technical, but it’s got to be messy and uneven, too. I had to keep reminding the guys not to plant in straight rows. What we’re trying to grow here is chaos. It’s got to be wild.”
NOW, TWO YEARS LATER, I didn’t recognize the place. I couldn’t get anywhere near Polygon 41. Standing on top of the buried SBR tanks, I looked down on the tops of willow trees, their canopies so dense that I couldn’t see the creek at all. Sprinklers placed high on the opposite hillside sprayed water over the expanse of green. “All that water comes from the treatment plant,” my uncle told me. “Usually when you do a project like this you never have enough water to get the plants established. But that’s not a problem here. They’re talking about sending some of the water over to a golf course, but until they do, we get all the water we want.” As if to prove his point, a set of automatic sprinklers came on next to us and started watering the hundreds of potted plants he had situated near the SBRs. “Those are for our next project,” he said. “This one turned out so well, now we’re restoring the next creek down the road. Flood control project.”
The dense vegetation over the creek has helped shelter endangered species. “I haven’t seen a garter snake there yet, but they’re hard to see anyway,” he told me. “Red-legged frogs are showing up, especially down in the creek where they’re hidden from birds.”
The monitoring plan calls for regular visits to the wetland over a five-year period to measure its success in the form of the water quality, survival of trees and shrubs, and the presence of wildlife. Once the five years have ended and the creek is entirely overgrown, the wetland will be left more or less on its own, with Gromm’s treatment plant crew watching the discharge of water and bird lovers walking the trails with binoculars, counting birds.
WHAT DOES ANY of this have to do with worms? As I toured the plant and walked the hillside with my uncle, looking down at the wetland below us, I realized what had happened here. Nature had been reengineered, harnessed, hired to do a job. If you allow a creek to go back to being a creek—if you let the trees and the bramble get overgrown, and you let the stream overrun its banks whenever it wants to—the wetland will take care of itself. The water that trickles into the ocean will be clean and pristine, if everything is just left alone to work the way it was designed to work. Earthworms have shown that they can take care of the soil in the same way that a wetland takes care of the water. Nature regenerates, it cleans, it hides a multitude of sins.
Does that give people an unlimited license to pollute? No, certainly not. But it offers a new way to look at how we manage our own waste. That’s not to say that the room on the back of my house that might have once served as an outhouse suddenly seems more appealing—I still prefer the gleaming porcelain and chrome of the bathroom upstairs—but I can understand now that the advancement of science, along with a more thorough understanding of the extraordinary powers of such natural processes as a worm moving through the soil, could suggest a more practical and effective way of managing waste.
“WATER RECYCLING PLANT” is a fairly accurate name for the Calera Creek plant considering that ninety-five percent of what the facility processes is water. But it’s no easy feat figuring out what to do with the other five percent, the biosolids. Because the finished product is so clean, its use is almost completely unrestricted. It can be spread on farm or forest land, used to fertilize plants in city parks, or given away in bags to local gardeners. The EPA’s literature is effusive on the subject of biosolids’ possible uses: “Nutrients found in biosolids, such as nitrogen, phosphorus and potassium and trace elements such as calcium, copper, iron, magnesium, manganese, sulfur and zinc, are necessary for crop production and growth. The use of biosolids reduces the farmer’s production costs and replenishes the organic matter that has been depleted over time. The organic matter improves soil structure by increasing the soil’s ability to absorb and store moisture.”
Biosolids may have plenty to recommend them, but the city of Pacifica, like many cities across the country, has not had an easy time giving the stuff away. For one thing, it stinks. “You know when that truck’s headed to the landfill,” my uncle said. “You can smell it coming and you can smell it going.” The other problem is that people just don’t want to spread human excrement in their flower beds or artichoke fields. Cow manure’s one thing. This is something else again.
Pacifica carts its biosolids off to a landfill at a considerable expense. Just giving it away would be an improvement; selling it to gardeners for a few dollars a bag, or selling it by the truckload to farmers, could even be a moneymaker. After all, Pacifica is at the northern end of a stretch of rich agricultural countryside. Most of the roses grown in the United States come from Half Moon Bay, just down the road. Cut flowers, strawberries, lettuce, pumpkins, artichokes, and Brussels sprouts all flourish along the coast and could benefit from a cheap source of good fertilizer, if it could only be made palatable to them.
That’s where the worms come in. If earthworms go to work on the biosolids after they leave the plant, the smell will be reduced, the texture will be more even, and the final product will be even more nutrient-rich. Above all, the concept is more attractive to the public. Language is everything here: earthworm castings from the water recycling plant sounds vastly more appealing than sanitized human waste from the sewage treatment plant. Farmers and gardeners might want it, and parks and schools might take some for their gardens.
David told me about this plan over lunch. “You know I say yes to whatever those guys ask me to do,” he said of the public works staff at the city. “And I’ve never regretted it. They want me to build a wetland, I build a wetland. They want me to find a way to help the fish get downstream, I’ve got guys trucking fish three days a week. Now they want a worm farm, and that’s what I’m going to give them. Is there any special kind of worm I need?”
I explained about composting worms like Eisenia fetida and how they’re different from the nightcrawlers that he was used to seeing in the soil. We talked about how the biosolids should be arranged: most worm farms place their feed in windrows, long rows about four feet wide and two feet tall. The worms start at one end and as fresh feed is added at the other end of the row, they work their way towards it. I toured a farm in Washington once where they process cow manure like this. The rows are laid in a U-shape; once the worms are finished at one end of the U, the castings are put through a harvester that spins it around and shakes out any remaining worms. That last step isn’t even necessary, I told him, if the city didn’t mind a few stragglers in its final product.
“You can buy a reactor and set it up in a warehouse if the city’s got the money,” I told him. “But if this is just a pilot project, there’s nothing wrong with worms in windrows.”
We went back to the treatment plant, where he’d picked an unused area to dump a load of biosolids. Finding a good location over the long term would be the biggest challenge. Each time he added fresh biosolids, the stink from the ammonia could be smelled a few miles away. It only lasts a day or two, but that is long enough to upset the neighbors. If they ever wanted to compost all the biosolids produced by the plant—several tons a week—a more secluded location would have to be found.
I knew from my talk with Bruce Eastman in Florida that the main challenge facing the city of Pacifica would be to make sure that the worms had a good food source. Class A biosolids that leave the plant at 160 degrees are basically sterile. The bacteria in the biosolids, both good and bad, have been killed, and these worms rely on living organisms such as bacteria as a major part of their diet. Nobody’s entirely sure if class A biosolids offer a good enough food source for the worms. Eastman suggested purchasing an inoculant from a laboratory but wondered if reintroducing bacteria would somehow change the status of the biosolids from class A to something lower. I called a waste management consultant who suggested mixing the biosolids with grass clippings or food waste to make sure the worms had something familiar to eat. David decided to try mixing green waste from one of his landscaping projects into the biosolids, which would decompose and offer the worms a food source.
That wasn’t the only issue. Worms are pretty picky about their environment, too. They prefer a temperature between sixty and seventy degrees. David would need to let the biosolids cool down before he introduced the worms to them. He’d also need to bring his pH meter and test the biosolids to make sure they weren’t too acidic. They like it damp; he’d need to water the pile during dry months. Finally, though, I knew that worms were sensitive to salt and ammonia content, and that’s where the real problem was. Last time the biosolids were tested, the ammonia was too high, and they had no idea what the salt content might be.
It can take a few weeks to do a soil test and get the results back, but David was eager to get started. Before I arrived, he’d dumped a load of biosolids on the piece of land he’d set aside, watered it, mixed in grass clippings, and driven a couple hours to Davis to pick up fifty thousand worms. “We can’t ship in this heat,” the worm farmer had told him, but David was all too happy to drive out to pick up the worms himself and inspect the farmer’s operation while he was there. He returned with three wax-lined boxes, each punched with tiny airholes and taped securely shut. Inside, tiny red worms—mostly juveniles, without the fully developed clitellum that marks an adult—squirmed together in a tight ball of worm bodies. They were packed in coir (shredded coconut fiber), but the boxes held far more worms than coir. They were heavy with worms.
The worms sat in the back of the truck while David and I walked over to check out the pile of biosolids. He handed me a pair of rubber gloves and suggested that we test the temperature before we added the worms. I hesitated for a minute, realizing that I had just been asked to put my hand into a pile of Pacifica’s collected excrement. But then I decided that I wouldn’t ask the worms to do anything I wouldn’t do myself. I put the gloves on and plunged my hand in the pile. It was hot to the touch. There was no way the worms would tolerate it. They’d have to spend the weekend in David’s garage.
The next week, the pile had cooled and David buried the worms in it. They were still alive and moving through it a month later. He’d set up a second pile, without worms, for test purposes: the city would run soil tests once a week to see if the ammonia naturally dissipated along with the smell. If so, the ammonia problem might just be solved by letting the pile sit for a few weeks first. The windrow design would be ideal for this: the worms would simply not enter the most recently added biosolids until they had cooled and until the ammonia level had dropped.
THE STAFF AT THE plant continues to work on the ammonia levels, and David is monitoring the worms as they work their way through the rows of biosolids. He tells me that he’s lucky to have enough time, enough land, and all the biosolids he can use. He can keep experimenting with each new load until he figures out what works for the worms. This is unfettered research, a process of trial-and-error and discovery, and in that way it reminds me a little of Darwin’s work, of his tireless experimentation with worms in jars.
People at the plant seem optimistic about the project. The food source is free. After the initial investment in earthworms, they will reproduce quickly to meet the increasing supply, and the finished product will surely be a fine soil amendment. There are still a few challenges ahead—if worms are going to consume all the biosolids the plant produces, they’ll have to find another location, one that isn’t upwind of the town’s residents. And for treatment plants that don’t produce class A biosolids, it remains to be seen whether the EPA will approve a process that uses worm composting to reduce the harmful pathogens.
I should also point out that people still have plenty of concerns about growing food in biosolids—in particular, the possibility that heavy metals can accumulate in it. The solution seems to be to prevent factories (and people in their own homes, for that matter) from pouring toxic substances down the drain in the first place. Every cleaning product, every paintbrush that gets washed out in the sink, every spill of oil or gasoline that runs down the gutter, eventually ends up at a sewage treatment plant like Pacifica’s. The level of heavy metals in sewage has declined over the last few decades, as industries are forced to find other ways to deal with their waste and the public is educated about the safe disposal of paints, solvents, and chemicals. A good biosolids composting project will have to monitor the level of heavy metals in the finished product. Earthworms can even play a role here as a biomonitor, allowing scientists to watch for long-term accumulation of heavy metals where biosolids have been used.
So there is more work to be done on all fronts. Still, it seems fitting that worms could find work turning a town’s waste back into something that local farmers and gardeners can use. In doing so, the worms exercise their transformative power. They are near the bottom of the food chain, a meal for fish and birds, while humans eat from the top of the food chain, consuming an astonishing array of what lives on the planet. But eventually, even we become food for worms. Shakespeare saw this connection, writing in Hamlet, “A man may fish with the worm that hath eat of a king, and eat of the fish that hath fed of that worm.” Should it come as any surprise, then, that earthworms have the power to transform human waste back into soil, where the cycle starts over again?
ALL THE TIME I spent at the sewage treatment plant got me thinking about something my husband, Scott, told me recently. He wants to build a chicken coop and get a couple of hens. He likes the idea of fresh eggs, and now I am attracted to the notion of all that chicken manure.
But soon I realize that the very best soil in the garden will be right under the chickens’ enclosure—the one place where I couldn’t grow anything. Imagine, all that chicken manure landing on the ground, and all those earthworms rising to the surface to eat it. The soil under those chickens will be the best soil I’ve ever seen. Shoveling out the manure isn’t enough. I need to find a way to make use of that hen-scratched, manure-laden earth under the coop.
I do a little research, and pretty soon I find plans for a portable chicken coop called a chicken tractor that can be moved every spring to a new spot in the garden. I walk my vegetable garden, mapping out a new design that will allow the vegetable beds to be grouped together into four ten-by-ten beds. One of those beds will be just the right size for a small chicken coop. Every year, the chickens will move to a new bed, and every year, I will come along behind them and plant vegetables in that manure-and-earthworm-rich mixture. The chickens themselves are interesting to me, but they will be Scott’s pets. I am more excited about what this means for me and the worms.
When it comes right down to it, my worms aren’t heroic or extraordinary in any way. They won’t solve the world’s pollution problems or treat sewage (apart from the chicken manure) or eat anyone’s garbage other than my own. They’ll just stay here in this patch of earth, along with me, and try to make the best of the environment they live in. Generations of worms will live on in the soil, long after I’m gone, long after this old house has fallen down. But they will renew the earth. What could be more extraordinary than that?
I GO BACK TO DARWIN once more, at the end of his life. In his final years, he seemed to look forward to joining the worms underground. Around the time The Formation of Vegetable Mould was published, he wrote to a friend, “I have not the heart or strength at my age to begin any investigation lasting years, which is the only thing which I enjoy; and I have no little jobs which I can do. So I must look forward to Down graveyard as the sweetest place on earth.” He was perhaps better acquainted than anyone else with the fate that awaited him, with the life cycle of which he would, in death, play his part. This did not seem to trouble him. He wrote that he had “no fear of death, after such a life.” One biographer wrote that when his hired gardener turned the compost pile, exposing the burrows of earthworms, Darwin “momentarily glimpsed his grave.”
He died on a spring afternoon in 1882. When it was announced that he would be laid to rest in the family plot near his home, a public cry went out to bury him instead in Westminster Abbey. One newspaper acknowledged that “Darwin died, as he had lived, in the quiet retirement of the country home which he loved; and the sylvan scenes amidst which he found the simple plants and animals that enabled him to solve the great enigma of the Origin of Species may seem, perhaps, to many of his friends the fittest surroundings for his last resting place.” Still, the newspaper argued, his proper place was not at the Down graveyard, in the company of his beloved earthworms, but in the Abbey, “among the illustrious dead.” There was strong popular support for this idea, and about a week after his death, Darwin was buried next to astronomer Sir John Herschel and near Sir Isaac Newton. There was little debate among the church leadership over the appropriateness of this decision. In a sermon following his burial, the Bishop of Carlisle described as foolish the notion that “there is a necessary conflict between a knowledge of Nature and a belief in God.”
In spite of this small reconciliation between Darwin and the church, it was no secret that Darwin’s faith during his lifetime was shaky at best. His work necessarily challenged some of the most deeply held teachings of the church, and he often struggled to keep his ideas private because he knew how inflammatory they would be. Notwithstanding the bishop’s kind words, the fact is that the conflict between a knowledge of nature and belief in God threatened the reputation of his family and even shook the foundation of his marriage to Emma, who hoped to spend eternity with her husband but feared she would not.
If Darwin had any notion of heaven, he surely believed that it was all around him. Adam Phillips in Darwin’s Worms suggested that in his study of earthworms, Darwin found for himself a kind of immortality, a kind of redemption, and a certain sly delight in the notion that worms created the earth. Phillips wrote that earthworms “preserve the past, and create the conditions for future growth. No deity is required for these reassuring continuities. . . . Darwin has replaced a creation myth with a secular maintenance myth. This is how the earth maintains itself, as fertile and ongoing.” Perhaps Darwin realized that the promise of eternal life, of resurrection, had been delivered. It was already happening, right beneath his feet.