SAN DIEGO — In these tawny hills high above city traffic, the road comes to a dusty end, marked by hexagonal caution signs that say, "Worm Crossing."
The worms don't really cross the road. Why would they want to?
Probably no worms on the planet have such an easy life as the 75 million earthworms that reside here at Canyon Recycling, which produces a material to improve the soil of gardens and lawns, like fertilizer.
Actually, the worms do the producing.
The worms are fed the leftovers of horticulture, the leaves and grass and chewed-up branches and other green waste that would otherwise clog landfills and create odors.
With help from the microbes that inhabit their digestive tract, the worms defecate what are called worm castings. This worm manure makes excellent soil or soil additives, holding moisture better, making nutrients readily available for plants.
The science is not new. Vermiconversion, or using earthworms to convert waste into soil additives, has been done on a relatively small scale for some time.
"But nobody's done it on a large commercial scale," said John Beerman, the general manager of the operation.
The soil additive is marketed in the form of mulch or compost or vermicompost, either in bulk or in bags. A 55-pound package sells for $7.
Canyon Recycling, which was started in January 1994, now handles 100 to 125 tons of green waste a day.
"The worm that we use is Eisenia foetida, which is the Midwestern redworm or the red wiggler," Beerman said. "They're a very active worm, very prolific, have a great appetite and live up to 10 years, which is quite amazing."
The more you feed them, the faster they grow.
Canyon's 75 million worms are out in the 20 windrows, each 20 feet wide and 250 feet long, that constitute the farm. There is a pound of worms for each cubic foot of windrow.
Since wriggly worms are tough to count, worm growers deal in worm weight, measured by the pound. When pressed, Beerman said, "You'll get about 1,000 worms per pound."
Each worm is hermaphroditic, which means it carries both male and female sex organs. This makes reproduction convenient.
"This is perfect because every worm they meet is a potential mate," Beerman said. "They can't miss. They really just sit around and have sex and eat."
An adult earthworm will lay one or two cocoons a week and out of those cocoons can come one to 10 earthworms. It may take 10 days for that cocoon to hatch and another 30 days for those worms to become mature enough to start laying cocoons.
"So if things are really going right, between the time an earthworm is born to the time it can hatch more earthworms is about 60 days."
The laboratory experts say if everything is perfect you can double your earthworm weight every 60 days. But for the men who have their hands in the windrows like Beerman, there is a certain conservatism.
He figures that the doubling occurs every 120 days.
Canyon Recycling has a vermiculture operation here for replacement worms and a reproductive facility in Yelm, Wash., where the sole aim is worm production to supply future operations.
"Up there," Beerman said, "we'll have from 25,000 to 100,000 pounds of worms depending on the time of year and how many we've harvested. We just delivered 5,000 pounds from Yelm to Temecula, Calif, where we're starting another vermiculture operation.
"We can't make enough earthworm castings to meet our demand here," he said.
"We put a price of $10 a pound on these earthworms. Most of the time sellers would want more than that. They would want $15 to $25 a pound."
In his conservative way, Beerman figures he feeds his 75,000 pounds of earthworms about 15 to 20 tons of green waste every day. "And we harvest that much out every day. Now, when we expand the herd [yes, herd], we want up to 100,000 tons."
Canyon Recycling was the beneficiary of the failure of another earthworm operation. North of nearby Escondido, the Fallbrook Sanitary District had an efficient operation that predated Canyon's by five years. They blended green waste with sewer sludge, that evil-smelling leftover after sewage has been treated.
They fed the mixture to the worms and "they did a phenomenal job of taking care of that waste," Beerman said. But the project was doomed by its own success.
"The communities began growing up around the sewage facility, and some developers put up houses adjacent to the sewage treatment plant."
This created odor problems. The resulting public outcry forced the operation to shut down.
So Canyon Recycling bought the Fallbrook herd.
"We don't do sludge here," Beerman said. "We are not permitted to and we will probably never do any. But there are other sites in the city that we are looking into and also other areas in California."
Besides the worm operation, Beerman's company uses huge, noisy grinders to chew up and compost cruder mixes, which are then sold back to the city and landscapers as mulch and cogeneration fuels.
Behind all this was a state law requiring municipalities to divert 25% of their solid waste away from landfills by the end of 1995. They did this, but that was the easy part--cans, newspapers, glass--or it was material that had to be recycled anyway, such as concrete, asphalt, wallboard.
"By the end of the year 2000, cities have to come up with another 25% of landfill diversion," said Beerman. "The next 25% is going to be much harder to achieve. That's where outfits like Canyon Recycling come in. We're a zero-discharge entity. We are 100% recycled. We don't bury anything.
"Nothing is wasted."