Hills of black gold: Walla Walla compost



With the Blues as backdrop, a front-loader aerates and redistributes a steaming pile of black compost at the city of Walla Walla Landfill at Sudbury Road. The composting process takes 120 days.


Clean, green waste, such as tree limbs, branches, leaves, grass and other waste is put through a grinder in the first step of compost production.

One doesn't often think of the landfill as a place for inspiration.

But talk to Donna Tisher and Brandon Leno about their work at the Walla Walla Regional Composting Facility at the Sudbury Landfill and they practically wax poetic about the clean green business of growing happy microbes and creating compost.

"The process is ancient," says Tisher. "We're essentially recreating what happens on the forest floor in 90 days."

The composting process allows green plant matter to decompose under carefully controlled temperatures not to exceed 160 degrees Fahrenheit.

At 131 degrees, pathogens, residual pesticides and herbicides are burned off and weed spores are killed, leaving a rich, pH-neutral, nutrient-dense material that can be recycled right back into people's yards and gardens.

"Our plants are ground up and go right back into our ground. The nutrients go full circle locally," says Tisher. She emphasizes that our local vegetation doesn't need the same nutrients that vegetation in another part of the country would, so it's better to buy compost generated locally.

The raw ingredients for local compost include clean green yard waste from residential containers, tree branches and limbs, leaves collected by the City of Walla Walla, wheat chaff, grass clippings and a small amount of grass-eating herbivore waste.

Each stage of the 120 day composting process requires acute observation. Tisher inspects a newly-arrived pile of green waste and spots a 5-foot metal planting stake in the middle, which she quickly removes.

Items such as these and any garbage must be removed prior to grinding to prevent injury to workers and equipment and to assure that the compost isn't compromised.

"Items like cans, bottles, shingles, concrete and glass may come from your yard as waste, but it is not considered green waste," says Tisher.

"People need to look at what they are throwing in their green bin and ask, 'Would I grind that up and put it in my garden?'"

After being inspected for foreign objects and trash, the compost is ground into small pieces and sits in long rows called windrows.

On a rainy morning, the windrows emit wisps of steamy vapor as the microbes do their work, looking very much like a black version of the soils around geysers.

Surprisingly, the smell is earthy and clean, not unlike the scents of harvest season. That's due to the diligent turning of the compost, accomplished with a front loader five times during an initial 15-day period, then on a regular but less frequent schedule until the piles are 90 days old.

The piles are watered as needed to keep them moist, depending on rain, along with regular aeration, to keep the environment as ideal as possible for the microbes. "We are growing bugs," says Leno proudly. "If we keep them alive and well, they do all the work." That work consists of breaking down the plant material, excreting nitrates and nutrients as byproducts.

After a final 30-day curing period, when temperatures indicate the compost has stabilized and matured, a sample is sent to a soil control lab for analysis and pathogen testing.

What is returned is a detailed nutrient, metal, stability and pathogen analysis for each batch of compost that must pass strict guidelines in Washington state.

Next, the compost is screened, which removes any remaining large pieces. The end result: 1/2 inch compost, sold directly to customers at the landfill.

The staff is equipped to fill anything from pickup trucks to buckets or trash cans, depending on the customer's need.

Last year, the facility also supplied compost to coarser specifications for the final phases of the U.S. Highway 12 project.

To use compost in your yard, Tisher recommends tilling your soil, then adding 2 inches of compost over an area, then tilling again. The compost will hold moisture in the ground, aerate the soil and provide vital nutrients. The result? Bigger, more beautiful plants -- grown naturally and without the use of chemicals and the satisfaction of helping to complete the cycling of local nutrients back into the soil.

What to put in your green bin

Clean organic waste items accepted: Tree trimmings, limbs (less than 16 inches in diameter), grass, leaves, garden waste, non-carnivorous animal manure, hay/straw/bedding (no twine), sod (no rocks), thatching

Items not accepted: painted or treated wood products, limbs or stumps over 16 inches in diameter, metals (nails, screws, pop cans), rocks, concrete, or brick, piles of dirt, carnivorous animal waste (cats, dogs, pigs, etc.), garbage (newspaper, styrofoam), cardboard, clothing, paper cups, construction waste, landscaping cloth, weedeater twine, shingles, tennis balls

Hours of operation: Monday-Saturday, 8:30-6:00. For more information, call 527-3746.


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