Washington: Seattle's Cedar Grove Composting Facility

Maple Valley and Everett, WA

Cedar Grove Composting, Inc., is a family-owned waste management firm that has served the Puget Sound area of Washington and Oregon since 1938. In 1989, Cedar Grove began large-scale composting operations, and started including compostable products in 2003. Before they can be accepted for composting, biobased products must be submitted to Cedar Grove for testing at its site. To qualify for on-site testing, products must already be BPI certified, meet ASTM D6868 or meet ASTM D6400. Testing trials start during the first week of each month.

About 500 groceries, restaurants, hotels, schools, and other food-service establishments and special-event venues segregate their food discards for composting at Cedar Grove. About one-third of these establishments use compostable plastic bags to contain their food discards. Cedar Grove also accepts residential yard trimmings from several cities, towns and counties. Cedar Grove and other commercial haulers pick up and deliver the food scraps to the Cedar Grove facilities where it is composted using the composting GORE™ Cover In-Vessel System. The final end products include soil amendments, soil blends and mulches.

Cedar Grove Testing BioProductsCedar Grove Testing BioProducts

Products and Brands Composted: 
  • Cold Cups: Fabrikal-Greenware, Gen-Pak Harvest, Eco Products, Solo Cup Company, Jaya, Ingeo, Nat-Ur, WNA
  • Hot Cups: EcoTainer, Planet+
  • Deli Containers: GenPak Harvest Collection, EcoTainer, Eco Products, Global Bio Alternatives, Versa Pak, Innoware, Burrows Paper Corp., Bridge-Gate, Cryovac NatureTRAY, Zenith Specialty Bag, Reynolds, Cont
  • Portion Cups: FabriKal-Greenware, Eco Products
  • Utensils: Nat-Ur, WNA. Global Bio Alternatives
  • Bowls and Plates: WNA EarthSense, Global Bio Alternatives, Gen-Pak Harvest Collection
  • Bags: BioBag, BioTuf, Comp-Lete, EcoSage6400, Nat-Ur, Eco film/Eco Works, Roplast Industries, Nature Friendly Products, Republic Bags, Bag-to-Nature, Al-Pack, EcoChoice, EcoGuard, EarthSafe

All of these products are BPI certified, meet ASTM D6400 or ASTM D6868 and have been tested by Cedar Grove Composting, Inc. Cedar Grove's comprehensive testing requires companies to submit their product's ASTM results for biodegradability data, heavy metals, average dry weight yields, and spectral analysis so they may be certified. Since testing trials start during the first week of each month, all required items and documentation, along with the sample profile, need to be received by the first business day of the month. A list of approved products can be found here.

Products approved by Cedar Grove display either a brown band or a transparent brown label that says, "CEDAR GROVE COMPOSTABLE." This system of labeling helps with quickly separating compostable plastics from those that will not biodegrade and therefore decrease the number of contaminants in the compost pile. Examples of labeled products can be seen below.

Collection System: 

The use of compostable food service ware has been on the rise in the Seattle/Portland areas (in part due to bans on polystyrene as well as the availability of composting facilities). Cedar Grove accepts compostable food service ware and organic materials from commercial clients as well as residential clients throughout the region's city, town and county programs. Cedar Grove carries out a site assessment to evaluate commercial client needs to recommend the best suitable program options. The company provides four different container options and delivers the containers to new participating businesses a week before they start the program. The Cedar Grove web site includes a list of approved biodegradable bags, a description of materials accepted for composting, tips on using compost products and a glossary of related terms. Cedar Grove and municipal staff provide 30-minute training sessions to the staffs of participating commercial food discard generators. Outreach materials are available in Arabic, Cambodian, English, French, Chinese, Hindi, Portuguese, Spanish, Tagalog, Thai and Vietnamese. Within 6 months of the initial training, Cedar Grove follows up and randomly audit 25% of clients after the first 6 months. A trainer is available to come to participating businesses to educate employees as often as needed at no additional cost.

Commercial haulers, including Cedar Grove, pick up food discards in toters or roll-carts (often lined with compostable plastic bags) and dumpsters, from generators in cities and counties throughout the Puget Sound region. Portland and Seattle contribute about 70% of the total. Groceries contribute the largest share, commonly 3 to 5 tons per week.

Compost Process: 

The organics are composted in Cedar Grove facilities located in Maple Valley and Everett, Washington. Cedar Grove uses the GORE™ Cover System composting system. Yard trimmings and food discards are processed in an aerated, in-vessel batch method, which is one of the largest such systems in the US. Batches are 450 tons each. Materials are actively composted for 60 days, and then cured for an additional 60 days. The final end products include several compost, topsoil and potting soil products, plus special custom blends. Most of the products sold are certified as organic by Washington State.

For a list of end products created, see: http://cedar-grove.com/products.asp

Size of Operation: 

The two facilities process 50,000 tons per year of food scraps mixed with 275,000 tons per year of yard trimmings.

Dollars and Sense: 
  • The finished compost sells for $18 per cubic yard in bulk.
  • Organics collection and composting fees per ton are commonly half of waste disposal service fees. Cedar Grove generally charge $40-$50 per ton, while transfer stations generally charge $80-$100 per ton.
  • Recycling is a non-taxable service.

One major challenge is when new food discard customers put all recyclables in the bins (other than acceptable list items). Cedar Grove then has to pick these out. Cedar Grove wants "compostable" items, not all "recyclable" items.

Tips for Replication: 
  • Cedar Grove requires that biodegradable bags used by clients be on its approved list and that contamination be below specified levels.
  • Some municipalities require Cedar Grove to provide on-site training to participating businesses.
  • Input quality is very important to output quality.
  • Because composting methods differ and are used in different climates, each compost facility operator must experiment to determine how best to integrate biodegradable plastics (as it would any other new compostable material).
  • Send materials through a grinder before, and screen after, they are composted.
  • Require that 90% of input biodegradable plastics be undetectable within 30 days of composting to provide a 30-day margin for final decomposition during the remainder of a 60-day composting process.
  • Provide education in the participants’ native languages.

Denise Foland
Business Development
Cedar Grove Composting
Hawaiian Earth Products
P.O. Box 2864
Tualatin, OR 97602
Cell: 971-219-2220
Fax: 503-612-1864
Toll Free: 888-832-3008