In 2003, research on appropriate composting technologies and design of the compost facility was initiated. There was no compost site in the County; source-separated green waste and wood waste were ground and marketed as mulch and/or biofuel. A small site on a closed section of the County's Buena Vista landfill, which could temporarily be used for composting, was identified. It was determined that an in-vessel system would be most appropriate, since odors, birds and leachate could easily be controlled.
Following an RFP process, the Versa Bagging System was selected. The facility was permitted in 2005 according to state composting regulations as a “research composting operation.” This permit allows for a small-scale (less than 5,000 cubic yards) project to operate for a fixed period of time - normally two years but it can be extended. Documentation of research objectives and findings is required, in this case to identify and resolve operation issues, including the use of biodegradable kitchen liners, and to identify component operational costs.
The County negotiated with its franchise hauler, Waste Management of Santa Cruz County, to allow for three day/week collection from about 30 businesses located in the most populous area of the unincorporated county. One and 1.5 cubic yard bins and 64-gallon carts were offered. Larger bins could not be offered due to weight restrictions on the loading mechanism of the rear loader truck. Waste Management agreed the drivers would keep logs detailing the approximate volume of material collected from each participant and information on any contaminants (glass, plastic, etc.) present in food scrap containers. Green Waste Recovery took over the hauling contract for refuse, recycling and compostables in May 2007, and assumed the duties previously performed by Waste Management.
Prior to start-up in November 2005, County staff and consultant met with prospective participants to determine what service would best fit each business (number of carts or bins, pick ups per week), to what extent refuse service could be reduced, and availability of space in the refuse enclosure for additional carts/bins. Food scrap collection was offered at half the cost of regular refuse. Bilingual staff training and posters with pictures of accepted materials, as well as 'Slim Jim' type kitchen collection containers and a year's supply of biodegradable bags, were provided to participants through the County.
Vision Recycling, the company that processes the County's green waste and wood waste, agreed to provide labor as well as yard trimmings to be used as bulking agent for the composting process and use of their bucket loader and screen. Vision staff is in charge of daily temperature record keeping and day-to-day operation of the compost site.
Dan deGrassi, of County of Santa Cruz, Public Works Recycling and Solid Waste Services, is present for major operations, including shredding, bagging and bag removal and he works with Vision Recycling to determine when
debagging, testing and screening should take place. He also maintains the program database, which includes temperature logs and laboratory analyses. County landfill staff manage repairs for the County-owned shredder (Bannerweld B-10) and bagger (Versa ID910). Both Green Waste Recovery and Vision Recycling document costs incurred for providing their services in order for the County to evaluate the overall cost-effectiveness of the program.
SAVINGS AT LARGER GENERATORS
Restaurants, markets, residential facilities and schools have been happy with the project. Based on reduced cost for food scrap collection, larger generators realize the greatest savings, with some restaurants able to achieve a cost reduction of thousands of dollars a year. For example, a business that generated 18 yards of refuse per week paid $1,200 a month for that collection. With half of that volume now going to food scrap collection, the refuse collection bill dropped to $540, plus $385 for food scrap collection. Linda Hopper, of Silver Spur Restaurant, managed to reduce her waste from three cubic yards per week to a 96-gallon cart. “It's been a great consciousness-raiser for me and my employees,” she says. “We all need to be more responsible about our garbage.”
Over time, more participants have signed up for the program, increasing the number of pick ups along the route by about 25 percent. Tonnage collected has also increased, from about 40 tons per month at start-up to about 90 tons per month as of May 2007. Self-haulers have joined the program; they are trained by County staff and consultant to keep nonbiodegradable items out of the food scrap collection and given a card to show to landfill gate staff to qualify for the program. Zero Waste event organizers are also allowed to bring clean loads of food scraps and biodegradable food service ware to the compost site by special arrangement. Gate fees for food scraps are half of the gate fees for refuse.
Keeping nonbiodegradable contaminants out of the food scrap collection has proven a challenge. “We want to generate a product that will be acceptable for a variety of uses, including organic farming,” says deGrassi.
During the first year, County staff and consultant delivered biodegradable bags to participants every two weeks. “It was a good chance to check their inside and outside containers for contamination and to discuss problems with them,” says Ana Maria Rebelo, County Commercial Waste Reduction Coordinator. “Most of the participants do a great job of keeping the food scraps clean, but a few need regular reminders, and we've had to cut a handful of participants out of the program because they just couldn't seem to get it right.” One problem has been that vendors and night-time janitorial staff often don't know about the program and don't notice the bin/cart labels or distinctive coloring (yellow bins and green carts). Unless they are locked and/or kept out of the areas accessible by the public, the bins may also be used by illegal dumpers or a passerby just looking for a place to put an empty soda can. Larger facilities and those with high levels of employee turnover seem to have a more difficult time meeting the standards. “Businesses where the manager has a high level of commitment to the program and is on-site most of the time generally have the cleanest food scraps,” says Rebelo.
RECEPTACLES AT SCHOOLS
Schools have been another trouble-spot for contaminants. Waste Free Schools staff Orli Loewenberg makes presentations to students and staff when a school signs on to the program, and again at the start of each year. Receptacles for recyclables, compostables and trash are provided. Lunch period yard duty staff and student monitors oversee the sorting of lunch residuals on a day-to-day basis. There numerous plastic items on the students' lunch trays - plastic wrap for carrots, saran wrap for napkin and spork, plastic straw and utensils, plastic fruit cup - make it very difficult and time-consuming for the students to separate their lunch waste into the proper receptacles. “When the kids finish lunch, they just want to dump their stuff and run out onto the playground,” says Loewenberg. “They do pretty well once they understand the sorting program, but we've found they need refreshers as the year progresses.” The County is also working with school district food service personnel to eliminate packaging and substitute biodegradables for some of the plastic.
Waste Management and Green Waste Recovery drivers have been helpful in spotting contamination and either notifying County staff or talking directly with the participants. Rebelo periodically follows the collection truck to check for contamination as the bins and carts are emptied into it and notes contamination for later meetings with participants.
When the food scrap truck unloads at the compost facility, any obvious contaminants are removed and the material is covered with an equal volume of tub-ground unscreened yard waste. When enough compostables have accumulated to fill a 100-foot long, 10-foot diameter bag, the food scrap/yard waste mixture is run through a Jenz (Bannerweld) shredder and packed into bags using a Versa bagging machine. While the shredding is a time consuming process, it is valuable in achieving size reduction (especially for the waxed cardboard) and thorough mixing of the feedstock. The material is composted in bags for three months, and aerated by rigid pipes that run the length of the bags. The pipes are attached to blowers with adjustable on/off timers. After removal from the bags, the compost is cured while being turned weekly with a loader for 8-10 weeks, then screened to 3/8 inch minus with a trommel screen. After screening, it is tested to the Composting Council's Seal of Testing Assurance standards.
The County receives 30 percent of the compost product for use in its Demonstration Program. The objective of the project is to demonstrate the practical application of compost in landscaping, erosion control and agriculture. Project participants are provided with compost at no cost in exchange for providing information on compost application and performance. Information is shared with the landscape, agriculture and erosion control professionals, as well as the community via articles, newspaper and television advertisements, and photos. Projects include use of compost for vegetable and fruit production on a local farm, soil improvement prior to planting turf and ornamentals at a County park, and erosion control on steep landfill slopes. The balance of the material is marketed by Vision Recycling.
Tom Broz, of Live Earth Farm in Watsonville, uses the compost to amend soil on his organic farm. “Compost is a pillar of our fertility management program,” he says. “We apply 5-8 tons every year or every other year to each field.” There are more than 70 organic growers in Santa Cruz County, with over 2,700 acres in production. Major crops include strawberries, bush berries and vegetables.
The compost program is part of the County's strategy to reach a goal of Zero Waste, with a milestone of reducing waste by 75 percent by the year 2010. The County is currently working with its four cities to find a larger compost site so that the collection program can be expanded throughout the County and include residential as well as commercial food scraps. According to a 1998 waste sort, 30 percent of the material in residential waste carts is food scraps/soiled paper. “We'd like to expand the program to that level,” says Patrick Mathews, Recycling and Solid Waste Services Manager. “More area for composting will be an important step to attaining the 75 percent diversion goal.”
BIODEGRADABLE BAG USE
FOR THE FIRST YEAR of the project, biodegradable bags were supplied by the County and distributed to participants by County staff and contractor. Restaurant managers are accustomed to using bags to line waste containers and most wanted to continue to keep the containers clean. Three brands - Nat-ur, EcoFilm and BioBag - all of which met ASTM6400, were distributed. In most restaurants, bags were used to line 23-gallon in-kitchen food scrap containers. Markets, schools and coffee shops generally found the bags unnecessary. At the end of the year, most restaurants wanted to continue using the bags and were able to purchase their own from local restaurant supply companies.
The number of bags used by individual participants varies greatly. In kitchens with lots of fresh-prep items, bags tend to get very heavy with moist food scraps and kitchen containers needed to be emptied by up-ending them into the carts and bins provided by the hauler; in restaurants with lots of bulky soiled paper and cups, bags tend to be lighter. In the first year of the program, the County spent $30,000 to purchase 51,000 bags for participants. Over 1,000 tons of food scraps were composted, for an average of 50 bags per ton of food scraps.
All of the bags proved successful. Participants initially thought the bags were too thin, and they are generally thinner than polyethylene bags that are used for regular refuse, but they proved tough enough to contain the food scraps during the collection period. The County eventually settled on BioBags, mainly because the green color provided a clear signal to restaurant employees, haulers and compost site staff that the bags were biodegradable.