New Approach to Old Landfills Blooms at Cal Poly Test Site

First came the landfill. Now comes the landscape.

And if researchers have their way, fragile oaks and native black walnut trees will soon sprout from a gaseous, 18-million-ton pile of garbage in Pomona.

Horticulturists at Cal Poly Pomona are mapping plans for the tricky planting project at the 197-acre Spadra landfill when it closes in late 1999.

They say they are borrowing ideas from nature in hopes they can nurture finicky walnut and oak seedlings in the most inhospitable terrain imaginable: sun-scorched ground that oozes methane gas and noxious fluids created by four decades of decaying trash.

Before trying to plant the trees, workers plan to seed the landfill’s steep sides and sprawling top with chaparral--native shrubs that grow wild on mountainsides around Los Angeles.

Experts predict that the thick brush will take root in time to shield and protect the oaks and black walnuts long enough for them to mature. Then the shrubs will die away, leaving sturdy groves of trees like those that welcomed valley settlers in the late 1800s.

The landscape plan is a bold departure for the Los Angeles County Sanitation Districts, which operates landfills across the county.

Until now, sanitation officials have taken the easy way out and done what most landfill operators do when it comes time to shut down a dump that is filled to capacity.

That has meant bulldozing a thick cap of soil over the last truckloads of trash and then turning the whole thing into a greenbelt or golf course by planting fast-growing eucalyptus and pepper trees and a variety of lush grasses.

What has been lacking in imagination has been made up for with irrigation.

The result can be pleasing to look at. But horticulturists say it also is artificial-looking for arid Southern California.

The Spadra planting plan took root 10 years ago when landfill operators signed an agreement with Cal Poly to expand the dump onto 115 acres of unused university land. In exchange, they agreed to give the school the entire landfill after it closes.

University administrators were quick to begin working the dump into their students’ curriculum.

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Since then there has been research on the landfill’s effect on animal life, the effect of animals’ burrowing on soil stability and landscaping’s effect on erosion control. Engineering students have also used probes to plot the settling of the landfill from garbage decomposition.

The centerpiece of what the university now calls its LandLab is the 2-year-old Center for Regenerative Studies--living space for 20 students who study conservation by growing their own food, doing their own recycling and experimenting with solar energy collectors.

A two-acre knoll next to the $5.5-million center’s dormitory and classroom area is where LandLab director and professor Ed Barnes has planted thousands of chaparral shrubs to test the brush cover theory. The hill is about a quarter of a mile from the dump.

“This is a prototype of what we can do,” Barnes said as he stood the other day among shoulder-high groupings of Mexican sage and mountain marigold plants. Because of this winter’s mild weather the 2-year-old plants were covered with blazing purple and yellow blossoms.

Barnes said the brush is considered “transitional planting” that will provide erosion control and attract wildlife back to the dump at the same time it is protecting the struggling oak and walnut seedlings.

Some of the brush will begin dying out after about two years; other shrubs will last as long as 15 years. By then, though, oaks and walnut trees should be thriving. With luck, they will grow for hundreds of years.

“Over the landfill, there will probably be pockets of intense landscaping, interspaced with grassy open space,” Barnes said. The idea is to camouflage monitoring pipes and erosion-control drains built into the landfill: “A faculty planning committee is helping develop a plan.”

Much of the knoll landscape work has been handled by 80 students at Casa Colina Career Development Center. It is a Pomona facility for people with physical or emotional disabilities that signed on as a LandLab partner in 1987.

“We take cuttings and grow them in a nursery,” said Paul Alderson, Casa Colina’s horticulture therapy manager.

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“It shows that people with disabilities can do tough work in the environment--on a mountaintop,” Alderson said as students Esther Sawyer and Rebecca Matthews harvested cuttings from an orange-blossomed lion’s tail bush.

California Conservation Corps workers have also chipped in--spreading the 30 tons of new mulch that was delivered by truck to the knoll one day last month.

Landfill operators say they are watching the chaparral and oaks experiment with interest.

“Admittedly, the approach being taken there is dramatically different than those at other sites, where we go with more ornamental green landscape, the more lush look,” said John Gulledge, head of solid waste operations for the Sanitation Districts.

Gulledge promised that his agency will stay involved after the landfill is closed. It is committed to spending about $250,000 a year after that on landscaping and vegetation maintenance.

Technicians will also continue to monitor and maintain environmental safety systems that have been installed as each layer of trash has been deposited. They control gas and fluid emissions and prevent erosion.

But the lessons being learned on the Pomona knoll could be put to use at the districts’ landfills elsewhere, Gulledge said. The county now has four active landfill sites and two closed facilities.

The former Mission Canyon landfill in the Sepulveda Pass between Brentwood and Sherman Oaks and Encino has partially been converted into a golf course; the Palos Verdes landfill currently has open space and horse facilities--although there have been discussions about development of a golf course there, too, Gulledge said.

“Whether we’d consider the native look at other sites depends on the local communities,” he said.

“Every site is its own unique animal.”