As California struggles with a mandate to reduce waste in state landfills by 50 percent, cities and businesses search for opportunities to comply. One significant contribution to the cause is green waste recycling.

“The biggest problematic waste stream in California is green waste and food waste,” said Mary Keil, an environmental protection specialist with the Solid Waste Programs for Region 9 of the Environmental Protection Agency (EPA). “They make up approximately 40 percent of waste in our landfills.”

While cities and counties deal with waste reduction on a large-scale, some green businesses are quietly working on small projects to help the state reach its goals. Not only does the state benefit, but the businesses do too -- in the form of reduced disposal costs. By avoiding the landfill, businesses also avoid tipping fees.

According to the EPA, average national savings over conventional disposal (in landfills) vary from $9 to $37 per cubic yard. The potential savings make the process worthwhile to businesses.

San Diego has won awards from the U.S. Conference of Mayors, Keep California Beautiful, and the California EPA for its green waste recycling program. The city collects green waste at 146,000 homes and process 90,000 tons of it into compost and mulch.

“San Diego has achieved approximately 48 percent reduction in the waste stream,” said Stephen Grealy, recycling program manager for the City of San Diego. Grealy is also a board member of the California Organic Recycling Council. “If we make a good faith effort, the state EPA will give a three year extension,” Grealy said. “We may get an additional two years if we still haven’t achieved our goal. But by 2005 we must meet the mandate or it’s a $10,000 a day fine.”

San Diego is number two in the state, tied with Oakland at 48 percent waste reduction. San Jose achieved 53 percent. The EPA set 1990 as waste year baseline. “Some cities were abnormally high that year, others abnormally low. That was the single most significant influence on whether cities are now meeting the goal,” Grealy said.

About 55 percent of the green waste collected comes from landscapers, 45 percent comes from city collection. The city started making a compost product in early 2000 to resell for commercial use, Grealy said. They ran out quickly because demand was so high. For businesses who create their own compost, the supply can be steady.

SMALL SCALE EFFORTS

The larger compost particles, a mixture of large pieces of bark and woody materials, can be used as a topper in planter beds, adding an attractive texture around the base of the plants.

“We began composting about four years ago,” said Alan Stockton, key accounts manager of Miramar Wholesale Nurseries. “We started by cooperating with Landtrends, a sister landscape maintenance company." The initiative was developed to support conservation and minimize dump fees. It was a win-win program that enabled both environmentally concerned businesses to save tipping fees and reduce ultimate plant mix costs by recycling green waste. Additionally the byproduct was used as a mulch on various Landtrends maintenance projects.

Together they developed the area’s sole in-house green waste program dedicated to landscape and nursery usage. As a result, in 1999 Landtrends received the Directors Award in Green Waste and Recycling from the City of San Diego’s Environmental Services Department.

TruGreen LandCare subsequently purchased both Landtrends and Miramar Wholesale Nurseries. And while the composting pile remains relatively small, the process continues. “TruGreen is committed to protecting the environment,” said Tom Smith, southwest region manager of TruGreen LandCare. “Composting, even on such a small scale, benefits the entire county, and it helps us as well.”

Not only is composting a good idea ecologically, it is also an excellent soil amendment and can have a major impact on any garden. Like making lemonade from lemons, the nursery and landscape company turn green waste into a beneficial product. About two years ago, Miramar started mixing the compost into soil used at the site to grow plants. A sifter and grinder filter trash and chew the green waste into useable size. Small bits are added to soil while larger chunks become mulch to use on top of plantings. The compost acts as an enhancement to preserve water and nutrients.

“This branch now recycles 95 percent of the green waste generated on landscape maintenance projects,” said Larry Neuhoff, San Diego maintenance branch manager for the Southwest Region of TruGreen LandCare. “We pre-sort to remove non-recyclable waste such as trash, palm fronds, and certain fibrous plant that won’t readily breakdown or may clog the shredder.”

When the crews return to the compound at the end of the day, the green waste is separated into two piles by size. Grass clippings, leaves and other material under one-half inch goes into one pile, everything over one-half inch goes into a separate pile. Larger items are shredded to reduce particle size.

"This is a voluntary, internal operation that provides us an organic soil amendment and reduces waste," said Suzie Wiest, branch manager of the nurseries. "It’s worked well for us and should work for other landscape organizations too. Quality control is a big issue ... we use the compost as a supplement to our soils, [so] we like knowing what is in it." The nursery grows more than 2.5 million plants on approximately 350 acres, so a steady supply of quality soil amendments is a great benefit.

DO YOU NEED A PERMIT?

The final compost product is run through a screen to separates the particles by size. Smaller particles are combined to creating a fine organic compost that will be mixed with soil.

As long as the project remains small, the “backyard” recycling program is effective for businesses. Larger operations, however, can require special permits.

“A compost pile that’s less than 2,500 cubic yards should be exempt from permits,” said Matthew Cotton, a technical consultant who specializes in developing and permitting compost sites. “The regulations can be a little vague, so always check the local zoning laws to be certain.” But 2,500 cubic yards is a pretty big compost pile. According to Cotton, that averages up to 10 feet wide by 100 feet long by 5 feet high.

Additional permits may be required if the business wants to resell the compost or mulch. Cotton said size is again a factor: if a company is producing compost and reselling it on a large scale another permit may be necessary. Projects like the nursery/landscape company partnership are very effective – both benefit, yet neither is burdened with the need for permits.

The EPA does not discourage businesses with large green waste output from pursuing a permit to process and/or resell compost. In fact, it lists the potential saving from reduced disposal cost and revenue generated from the sale of compost, mulch and soil blends as direct benefits to businesses.

“Another way to reduce waste is by grasscycling,” Grealy said. “Many landscapers use this practice. It’s using a mower that chops the clippings so fine that they don’t have to be collected – the clippings remain on site. This process can cut waste, cost and fertilizer use. No one has to stop mowing to dump bags or cart the waste anywhere. We do this in all golf courses (except greens) in San Diego and in all city parks and recreation departments.”

After collection, the city creates and distributes compost at the Miramar Landfill Greenery. “We’re very careful,” Grealy said. Like Wiest at Miramar Wholesale Nurseries, Grealy said quality of green waste is paramount. “The main idea is be consistent with quality. We compost everything to kill weed seeds and pathogens and diseases. And we're very strict about no garbage.”

Vigilance is important to the quality of the product. “Businesses who want to develop their own compost facility should be aware of the work involved in maintaining quality control,” said Joshua Dake, inventory control manager at Miramar Wholesale Nurseries. Dake offered the following tips on maintaining a composting operation.

THE PROCESS

Larger compost chunks become mulch to use on top of plantings, acting as an enhancement to preserve water and nutrients. Compost creates an attractive and effective top coat for soil in beds.

Compost is highly regarded for its ability to improve soils, which greatly enhances plant growth. Because of its lack of nutrients, compost alone cannot grow plants. However it is beneficial to the soil, improving the soil’s structure, water penetration, and moisture holding capacity. It can help prevent erosion and weed germination, while increasing the overall productivity of the soil.

A good composting operation depends on several factors: materials, moisture, carbon/nitrogen balance, air flow, and temperature. Any one of these factors can greatly affect the success of the operation and the quality of the product.

MATERIALS

Compost improves the soil’s structure, water penetration, and moisture holding capacity. It can also help prevent erosion and weed germination, while increasing the soil's overall productivity. Seen here is the Morbark, Inc., 737 Trommel Screen, which offers 660 square feet of screening area.

The single most important element in production of quality compost is the incoming green waste. At Miramar Wholesale Nurseries, the greens used are a combination of grass clippings, leaves, foliage, and wood. A staff member is located at the dumping site to direct the waste into the appropriate window. This is to ensure that the material is free of trash and that the proper ratios of Carbon and Nitrogen can be monitored.

CARBON/NITROGEN BALANCE

The screen sifts the compost and sorts it into piles by size. A good composting operation depends on several factors: materials, moisture, carbon/nitrogen balance, air flow, and temperature. Any one of these factors can greatly affect the success of the operation and the quality of the product.

Carbon provides energy to bacteria, fungi, and other microorganisms, which make the decomposition process happen. The major sources of Carbon to the compost pile are leaves and foliage, with a Carbon to Nitrogen ratio (C:N) of between 40 – 80:1, and woody materials with a C:N ratio of 100 –130:1. Nitrogen expedites population growth of these microorganisms. Therefore, if there is too little Nitrogen, the populations will not grow to their optimum size, slowing down the rate of decomposition.

On the other hand, excessive Nitrogen will cause an accelerated rate of microbial growth and rapid decomposition of the material. This rapid decomposition will generally result in overuse of oxygen in the pile, creating an anaerobic situation, and serious odor problems will occur. Grass clippings are the main source of Nitrogen in the compost pile with a C:N ratio of 19:1. The ideal C:N ratio is around 30:1.

MOISTURE

Not all green waste needs to compost. Large pieces of woody material may be dried and processed through a grinder to create mulch. The grinder pictured here is Bandit's Model 3680 Beast Recycler™.

Moisture needs to be monitored and managed carefully. Moisture content should never be below 40% and never above 70%. If a pile is too dry, decomposition slows because the microorganisms do not have sufficient moisture to thrive. If a pile is too wet, anaerobic conditions occur because the water fills up all available pore space and does not allow sufficient air to flow. To prevent this excessive moisture, the pile should be turned on occasion to let the wetter material on the bottom of the pile dry out, and to get air to the bottom of the pile. In arid climates such as Southern California, it is a good idea to make the top of the pile concave to trap whatever moisture is available.

AIR FLOW

Composting is an aerobic process. That means that oxygen flow is crucial to a properly functioning compost pile. If the percent of Oxygen in the pore space falls below 10, the pile can become anaerobic and methane gas will be produced resulting in an odor. In a large pile, Oxygen naturally circulates through the pile by entering through the bottom and sides, while the hot air rises from the hot core and exits through the top. However, it is a good practice to consistently turn the piles. This will create a more uniform rate of decomposition, increase temporary Oxygen to the pile, and loosen the pile to promote better natural Oxygen flow.

TEMPERATURE

When temperatures exceed 160 degrees Fahrenheit (71 degrees C), beneficial organisms are killed off. Below 90 degrees Fahrenheit (32 degrees C), the decomposition process is slowed down considerably. Ideally, temperatures should be kept between 90 and 140 degrees Fahrenheit.

The temperature in the compost pile is determined by two factors, the heat produced by microorganisms, and the heat lost on the surface area. After a pile heats itself, temperatures will drop because there is less material for the microorganisms to decompose. By turning the pile, temperatures will rise again due to a rejuvenation of decomposable material. Therefore, the pile should be turned as temperatures rise above 140 degrees, or fall below 90 degrees. Eventually all of the decomposable material will be consumed and the pile will stop heating. Once the pile reaches a steady temperature of around 70 degrees, the composting process is done.

The final product is run through a screen, which separates the particles by size. The smaller particles are put in one pile, which is a fine organic compost that may be mixed with soil to create a planting mix. The larger particles, a mixture of large pieces of bark and woody materials, can be used as a topper in planter beds, adding an attractive texture around the base of the plants.

Composting is only one method to recycle green waste. Reducing green waste before it is created is also beneficial. Grasscycling is an option, but landscapers can also help reduce green waste by educating clients before an installation project begins. Some types of work are more wasteful than others, such as planting a hedge or planting a tree under power lines. Both require frequent trimming. Xeriscaping is by nature a resource-saving technique.