Mira Mesa residents Bing-Lin Zhou and Mao-fejule Lue

The Miramar Greenery in the Miramar Landfill offers free mulch and compost to San Diego residents, materials that could provide some relief during drought-tightened water restrictions.

José Ysea

"Compost when incorporated into soil before planting helps reduce water/irrigation needs by providing healthy soil tilth, which maximizes the amount of time water stays in the plant root zone," said José Ysea in an April 9 email on behalf of the City of San Diego Environmental Services Department. "Mulch when used as a top dressing reduces [irrigation] evaporation and also helps provide soil stability and nutrients."

Ysea gave me a tour of the greenery, where more than 100,000 tons of compost, mulch, and wood chips material is processed annually. About 12,000 cubic yards of compost and mulch is given away.

A cubic yard equals six 32-gallon trashcans, and residents can self-load up to two cubic yards of free material. Prices per cubic yard include $5 for mulch, $12 for compost, $24 for natural wood chips, and $34 for chips dyed red or brown. Sales aren't limited to city residents.

Yard waste

Mulch is made by processing shredded yard waste for two to three weeks. Compost consists of yard and food waste that is ground and processed for four to six weeks. Greenery may come from residences or businesses; Ysea said food scraps were diverted through the commercial food-waste recycling program. (Some participants also donate edible food to charitable organizations.)

Natural-wood chips were once logs and branches. Plain wood chips made from pallets and lumber are sold as is or dyed. "Usually the most popular color is brown," said Ysea.

Air cannon

He said the landfill is a tenant on Marine Corps Air Station Miramar land, an arrangement that includes a bird-control program. Methods include an air cannon that blasts to scare away birds such as seagulls and ravens so they aren't sucked into jet engines.

In the compost area, Mira Mesa residents Mao-fejule Lue and Bing-Lin Zhou filled white trash bags. Bing-Lin Zhou held a bag and said, "This is our first time; our neighbor told us about [the free material]." As Mao-fejule Lue shoveled, she said, "Before, we'd buy compost at Home Depot."

Ysea showed me machinery and spoke about contaminants that could damage grinding machines. Greenery staffers check hauls for inappropriate items, usually bottles or bags. "I was at the landfill a few years back when an engine block was discovered" in the yard clippings, he said.

Food waste

In the food-waste area, Ysea spotted yogurt cups and a soda can. Since the city knows where the waste came from, the institution will be notified. After a certain number of violations, the organization can't participate in the program.

The food-waste program started in 2001, with the Marine Corps Recruit Depot as the first participant. While the number of recruits varies, about 12,000 meals are served each day, and approximately 17 tons of food is compacted each week.

Petco's program started in 2005. By 2007, the park diverted an average of 1.7 tons of pre-and post-consumer food waste per game during baseball season, according to the environmental-services website. After games and major events, food waste from concession stands and restaurants is compacted and hauled to the greenery, according to the Padres website. ”The [resulting] compost is periodically returned on site for use in the ballpark landscaping." The park also sends grass clippings from the playing field to the greenery. Ysea said, "Their green-waste program is a perfect example of sustainable green-waste recycling. They provide the raw material…we provide them with finished products such as compost and mulch."

The food-recycling program isn't open to residents. However, the city offers discount vouchers for compost bins purchased at Dixieline ProBuild. There were "just under 1000 applications" for vouchers in fiscal year 2014, with an approximately 60 percent redemption rate, Ysea said. During the current fiscal year (which ends June 30), there were 870 applications as of April 9.