By Paul Brewer

Since the beginning, Navy Whidbey Recycle knew that a composting program would be the next big step in the reduction of the wastestream. Navy Whidbey Recycle opened the first Department of Defense in-vessel composting system. In 2002, its first full year of operation and testing the compost facility successfully produced 1,288 tons of Class AA compost.

Every aspect in planning the composting facility was designed to reduce the impact on the community and environment. The facility was located in an unpopulated area of the naval air station (NAS) on Whidbey Island, WA, and in-vessel containers are in use to control the potential of odor from composting. The facility is designed so rainwater runoff is collected on-site to be used in the compost mixing process, saving tens of thousands of gallons of fresh water annually. The leachate is collected in a 4,000-gal. tank and is reintroduced back into the compost recipe.

The composting program enables Whidbey to collect foodwaste from the galley, restaurants, and commissary store along with yardwaste, waste paper, and shredded paper, removing almost 50 tons a month more from the wastestream during the initial testing and startup period. In 2002—the first full year—compost operation increased to a high of 122 tons a month of biodegradable solid waste from the wastestream. The design of the compost facility allows for expansion by putting in an additional vessel as volume increases.

Environmental Controls

In-vessel containers are monitored by a computer system that controls the airflow to increase or decrease the temperature as needed. The temperature is evaluated and recorded to ensure the Process to Further Reduce Pathogens (PFRP) is met and to alert operators if a batch goes anaerobic. The containers use a drainage system to divert all leachate into a holding tank. When the compost has completed its cycle, it will be dumped using a rolloff truck. Any batch that is not completed and needs a remix is dumped into a covered building with a drainage system that runs to the leachate collection tank. The leachate collection tank is fitted with a high-level warning alarm and is checked on a daily basis. If the leachate tank is full, a suction truck is called to dispose of the liquid in accordance with local, state, and federal regulations. Rainwater is collected in a 10,000-gal. tank and can be used in the composting process. With the average rainfall in the area being so high, a runoff system was installed in the tank that allows excess water to be diverted to a bioswale.

During the first year, testing was conducted on all compost material. The testing allowed fine-tuning of the recipes and also guaranteed use of the finish product around NAS Whidbey Island. Periodic testing is conducted to maintain Class AA compost standards. Compost is also spread in test areas and monitored throughout the season. The closure of the Ault Field wastewater treatment plant lagoon led the way to biosolids composting as a cost-effective alternative to land application or landfilling. During the testing phase, the utmost care was taken in the handling of the biosolids before and after the process. The finished compost from the biosolids has been spread in a test area for observation. Even though the biosolid compost has passed all its health and quality tests, Whidbey will use the compost only in unpopulated areas.

Performance

Since the beginning of the compost program, a total of 1,757 tons of material have been diverted from the wastestream, accounting for 21% of an overall 65% reduction of the air station wastestream through various diversion programs. With more housing units being occupied this year and with the potential of more biosolids composting, that number is expected to grow another 10%, equaling a 75% reduction. The composting of foodwaste and yardwaste has exceeded the original goal threefold. The refuse cost avoidance to the naval air station from composting totaled more than $200,000.

Cick here for larger view

Water conservation and water recycling are implemented at the compost facility. Along with the 10,000-gal. water tank, the compost facility also uses clean water discharged from a base Superfund pump and treatment system. The process was approved and applauded by the United States Environmental Protection Agency for both conserving natural resources and providing beneficial reuse of materials from a Superfund cleanup site. Water use at NAS Whidbey Island has declined by more than 8.3 million gal. since 1999.

Last year 345 yd.³ of compost were issued for use around the naval air station. Local Seabees used 45 yd.³ with topsoil around a building and are expected to use more compost this year.

The busiest time for the compost facility is the grass-growing season. On top of the 199 tons collected by the compost crew, another 274-plus tons are dropped off by a private firm contracted to mow the base. All 199 tons of yard clippings were generated adjacent to base housing units (1,550 units), roughly one-third of which were unoccupied in 2002 for remodeling. The total amount of yardwaste collected for 2002 was 473 tons, and the total foodwaste collected was 172 tons. These wastes then are mixed with bulking agents consisting of wood products, waxed cardboard, shredded paper, and carbon paper. By planning ahead, the program processed a grand total of 1,288 tons of material.

Wastestream reduction coupled with refuse disposal cost avoidance is the prime focus at NAS Whidbey Island. Since the composting program began, more than 1,757 tons of biodegradable material have been diverted from the wastestream at a cost savings of more than $273,000. Composting accounts for 20% of the recycle material diverted from the wastestream.

Composting Equipment

Navy Whidbey Recycle compost facility is a simple plan and process. It was set up this way to help the recycle center manage its time and increase productivity with as few operators as needed. The compost center is a two-person operation for collection, processing, and screening. Both employees at the compost site are trained to run all the equipment and monitoring systems.

Only a handful of equipment is needed to operate the facility. Such equipment as the auger truck has a dual purpose: as a collection truck and a mixing container. A minimal amount of wood chips is loaded into the collection truck prior to going on the assigned route. As part of the collection process, material dumped into the container is mixed. Once everything is collected, the crew finishes off the precompost process with more wood chips, paper, and water until the desired recipe is achieved.

An automated computer system at the facility allows for hands-off operation of all control measures and records all events for future analysis. An audible bell warns operators if a container is out of specification. Trends from previous compost batches are used to improve future compost batches. The system helped during the biosolids composting trial by allowing the operators to experiment with different recipe mixes, minimizing the amount of time to reach the PFRP.

Environmental Philosophy

Navy Whidbey Recycle's philosophy is to make composting and recycling easy for customers. Unlike other recycle drop-off areas, Navy Whidbey Recycle has a full-time employee to greet every customer and is on hand to assist in any way possible. The public drop-off area not only accepts more material than the average recycle center, it has been set up to allow more people into the facility at one time. Larger containers are in place, each with a written description of what can go into that container. Samples of the allowable materials hang above each bin. Shopping carts are available for customers to use to bring the material from their vehicles to the building, and larger carts also are on hand for the bigger loads. Customers with an abundant amount of recyclables are allowed to drive through the building and drop off the recyclables at the processing point. Vehicles that do drive through the facility are guided through to ensure safety to the public and employees.

Whidbey provides 65- and 95-gal. containers to customers for biodegradable materials. Wood products may also be dropped off at the recycling facility for chipping. Cleanliness is a high priority for the whole recycle center and compost facility but especially in the public drop-off area.

These and other reductions of wastes at NAS Whidbey Island continue to meet and exceed federal, state, and local regulations. Many things contribute to the results. But Whidbey's success mostly has come from an employee mindset shift. From day one, composting and recycling become a way of life. Avoiding disposal costs through source reduction becomes as much a part of their jobs as "Keep 'em flying!"

Paul Brewer is environmental protection specialist with Navy Whidbey Recycle, NAS Whidbey Island, WA.

MSW - September/October 2003