Soil specialists look for loam improvement

Garn Wallace has the dirt on Los Angeles’ underside.

“The best soil is in the center of the San Fernando Valley. Closer to the hills you have a high clay and rock content,” he says. Downtown Los Angeles is sandy. Soils next to freeways are laden with lead and other toxins.

Wallace should know. Along with three of his children, he operates one of the city’s busiest soil-testing laboratories.

Their clients range from backyard gardeners curious why their vegetable patches aren’t producing fat tomatoes to commercial landscapers who oversee planting programs worth thousands of dollars.

Thanks to their El Segundo lab, a 14-mile slash of lush vegetation grows along the Metro Orange Line between North Hollywood and Canoga Park, and decorative landscaping thrives at Disney’s California Adventure theme park.

“The Orange Line was built on what had been an old rail line and the railroad had used arsenic, boric acid and organic herbicides to keep weeds from growing along it,” Wallace said.

Wallace’s tests prompted Metro officials to scrape away the tainted earth before 800,000 shrubs and 8,000 trees were planted along the busway. If they hadn’t — arsenic doesn’t decompose — it would have eventually killed the $35 million worth of greenery in what was supposed to be a greenbelt, he said.

In Anaheim, Wallace discovered that the 55-acre California Adventure site contained soil too sandy to support the landscaping planned for it. He suggested that a foot and a half of dirt be replaced in planting areas.

His skills are in demand overseas too. So far this year, he’s made six trips to test soil conditions at a new Disney park site in Shanghai.

Such commercial jobs, coupled with governmental contracts, make up about 87% of the lab’s work. Residential clients and agriculture assignments constitute the rest.

Those who rely on Wallace’s expertise say Los Angeles is a place where they must know their dirt. “We live in an urban environment where soils get damaged over the years. Most of the good soil is covered with roadways and buildings,” said Cal Walsten, a veteran Altadena landscape architect.

Venice landscape architect Polly Furr said Wallace can spot soil compaction, clay composition and air pockets that can affect drainage, as well as heavy metals from fertilizer that affect plant growth. “That’s critical, because you can make a nice landscape for today, but it’s also our responsibility to make it grow in the future,” she said.

Wallace, 67, and his now-deceased father, Arthur, started Wallace Labs in 1991.

The elder Wallace had been working with UCLA’s College of Agriculture, which once had 14 acres of orchards between Le Conte Avenue and Sunset Boulevard, Garn Wallace said.

Wallace, himself a UCLA graduate with a doctorate in biochemistry, was working at the time as a research biochemist at the Westwood campus. He had gotten his first taste of chemistry work in high school when his father got him summer jobs as a laboratory helper at the university.

“That’s where I found out that science is interesting,” he said.

But UCLA’s stake in soil began to wither on the vine, and grants were drying up. So his father mortgaged his West Los Angeles home to buy instruments and equipment, and the pair opened their own lab.

It didn’t take Garn Wallace long to embrace his new line of scientific research. “In high school I hadn’t liked to get dirty,” he said with a laugh. “I got over that when I started making money collecting soil samples.”

During last week’s rainstorm, Wallace got dirty — and wet — on an emergency soils test call in Beverly Hills. A landscape architect needed dirt analyzed at a large residential project site by Friday. Wallace and his son and two daughters easily met the deadline.

Wallace’s son John, 33, said some 5,000 soil samples a year arrive by mail or are hand-carried in plastic zip-lock bags for analysis. Averaging about two cups each, the scoops of dirt are poured onto screens to filter out any non-dirt debris.

Gravel, ants, nails, glass and coffee grounds are sometimes discovered in the sealed bags, he said. Such items can cause misreadings on the $100,000 inductively coupled plasma spectrometer that analyzes 30 elements per minute.

Liquid is added to the dirt to turn it into mud that is the consistency of a milkshake. The liquid is extracted by a vacuum device before the testing can begin.

John Wallace, who has a chemistry degree from Cal State Dominguez Hills, said he admires the lab that his father and grandfather created. “I’m here by choice, not the crack of a whip,” he said.

His sister, Elizabeth Wallace, 29, said she initially planned a career in nursing: “I wanted to do my own thing. But I switched to chemistry [at Cal State Long Beach] when I noticed that people are surprised that there’s pollution in soil.”

The other sister, Rebecca, 23, graduated from Brigham Young University and says she digs psychology more than dirt. But Garn Wallace figures he’s still positioned to keep it a family-run business for generations to come.

“I have nine kids and 14 grandchildren,” he said.

bob.pool@latimes.com