Outdoor Furnishings - Recycled Plastic Lumber

Environmental and Health Issues and Recommendations

Plastic lumber is generally manufactured from 25 percent to 100 percent by weight preconsumer and postconsumer plastics, or a blend of recycled plastic with other materials such as wood fiber, glass fiber, rice hulls, peanut shells, and rubber.

• Purchase plastic lumber with at least 10 percent by weight postconsumer plastic. Higher postconsumer plastic content is recommended.

By using materials that have been diverted from the waste stream (e.g. plastic, wood, rubber, etc.), recycled plastic lumber (RPL) conserves landfill space. As a substitute for other materials, such as wood, concrete, and metals, RPL helps to reduce the consumption of our natural resources, thereby reducing the impacts that resource extraction can have on human health and the environment.

Although RPL contains chemical additives, they are not released into the soil or water. For this reason, RPL is offered as an alternative to treated wood, which has been blamed for leaching hazardous materials, such as arsenic.

Currently, there is no collection infrastructure for RPL in California since this is a relatively new durable material. Manufacturers offering take back programs should be preferred.

Plastics represent 9.5 percent by weight, or 3,809,699 tons, of the total solid waste disposed in California. [1] Almost half of them are film plastic, which is one of the main feedstocks used in the manufacture of RPL. As we strive to be a zero waste state, we must manage this waste by first preventing waste whenever possible and managing all "waste" materials to their highest and best use.

Effective plastics management keeps them out of landfills and prevents the impacts associated with the extraction of oil.

See the Introduction for complete descriptions of these environmental and health issues.

• Background and Environmental and Health Issues
  • Recycled Content
  • Less Hazardous
• Laws and Guidelines
• Performance
• Availability
• Cost
• Tips on Buying RPL
• Specifications
• Vendors and Manufacturers
• Success Stories
• Resources and Web Sites

BACKGROUND AND ENVIRONMENTAL AND HEALTH ISSUES

Recycled plastic lumber (RPL) comes in different varieties depending on the types of materials used. RPL, for instance, could be made of pre or postconsumer high density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), and mixed plastics. However, most RPL is made entirely of HDPE, the material used in milk jugs and liquid laundry product bottles. Postconsumer plastic film is another good source of RPL. The plastic component can also be blended with additional materials to form a stronger product called composite plastic lumber. Some of the materials used in the composite product include natural and synthetic fibers (e.g. rice hulls, sugar cane, wood, and glass), rubber, minerals, and metals.

RPL was used initially in applications that do not require critical load-bearing such as picnic tables, park benches, partitions, trash receptacle covers, dimensional lumber, and landscape timbers. RPL picnic tables and park benches are considered worthwhile, but the demand is just not great enough to divert any significant amount of plastics from landfills. [2]

RPL used in outdoor structural applications such as decks, boardwalks, railroad ties, and docks, instead, promises to capture a greater portion of the market, and will use huge portions of plastic waste. The United States (U.S.) railroad industry, for example, replaces approximately 14 million wooden ties a year out of the nearly 700 million ties used annually. It is estimated that the replacement and installation of new wooden ties costs the railroad industry over a billion dollars a year. RPL ties could be used as an alternative to wooden ties. Each RPL railroad tie requires 200 pounds of plastic - equaling 1,200 bottles. [3]

The use of RPL as a substitute for pressure treated lumber is another attractive market, considering that in the U.S. alone, the market for pressure treated lumber is estimated at about $10 billion ($4 billion for decks in houses). [4] However, the leader in sales volumes for RPL (35 - 55 percent of the market) is commercial and residential decking. The agreement between the United States Environmental Protection Agency (USEPA) and the U.S. lumber industry to phase out arsenic compounds from pressure treated wood is helping to support the growing market of RPL in decking applications. The park and recreation market, with 20 percent to 30 percent of the market, is no longer the largest market for RPL. Railroad ties represent only 7 percent to 15 percent of the RPL market. [5]

Environmental and Health Issues

Recycled-Content

Environmental and health benefits also make RPL a good choice. The manufacture of RPL from postconsumer and postindustrial resins is promising as it consumes large amounts of material that would otherwise be sent to landfills or become litter. Even small quantities of RPL can remove large amounts of plastic from the waste stream. More than 750 recycled milk jugs and detergent bottles, for example, are used to make a single four-foot long plastic bench. [6]

Less Hazardous

RPL is an alternative to treated wood, which has been blamed for leaching hazardous materials, such as arsenic. Although RPL uses several chemical additives such as antioxidants, biocides, heat and light stabilizers, lubricants, and flame retardants, they do not leach into the water or the soil because they are encapsulated in the plastic matrix.

LAWS AND GUIDELINES

California

Statute

State Agency Buy Recycled Campaign (SABRC)

• Recycled-Content Product Procurement Requirements
  • Public Contract Code (PCC) section 12203 requires State agencies (including California State Universities) to ensure that at least 50 percent of the dollars spent on plastic products be spent on plastic products with at least 10 percent postconsumer recycled content [exception: see content requirements for printer and duplication cartridges in PCC 12209(f)(2)].
  • The SABRC plastic products (PL) category includes, but is not limited to, printer or duplication cartridges, diskettes, carpet, office products, plastic lumber, buckets, wastebaskets, containers, benches, tables, fencing, clothing, mats, packaging, signs, posts, binders, sheet, building products, garden hose, and trays (see PCC section 12207).
• Recycled-Content Certification Requirements
  • PCC section 12205 requires all State agencies to obtain from all suppliers written certification of the postconsumer recycled content of each product offered or sold to the State. Recycled-content certification forms are available in the SABRC training manual.
• Recycled-Content Product Procurement Report
  • PCC 12211 requires PL purchases to be reported in each agency's annual SABRC Procurement Report.
• Recycled-Content Product Procurement Contract Language
  • PCC section 12217(f) directs State agencies to remove contract provisions that impede the consideration of recycled products and to replace them with performance standards.

Regulation

The California State Fire Marshall's (SMF) Office has developed building codes for areas within the Wildland-Urban Interface Fire Area as defined in Title 24, California Code of Regulations (CCR), section 702A. 24 CCR 704A.4 states that "decking, surfaces, stair treads, risers, and landings of decks, porches, and balconies" or any portion of located within 10 feet of the primary structure will need to meet the testing requirements established. Decking material not heavy timber or treated with fire retardant would need to pass the performance requirements of SMF 12-7A-4 parts A and B. These requirements test the decking material to ensure that flames will not spread as a result of specific contact. The aforementioned regulations were approved on September 21, 2005 and are available on the SMF's Web site.

Federal

The Resource Conservation and Recovery Act requires procuring agencies to buy recycled-content products designated by the USEPA in the Comprehensive Procurement Guidelines (CPG). A number of RPL products are USEPA-designated items. Procuring agencies include all federal agencies, and any state or local government agencies or government contractors that use appropriated federal funds to purchase the designated items. If your agency spends more than $10,000 per year on a product designated in the CPG, you are required to purchase it with the highest recycled-content level practicable. [7] This means that the recycled-content ranges recommended in the USEPA's Recovered Materials Advisory Notice (RMAN) for the item in question are met. [8],[9] The USEPA's recommended recovered materials content levels for RPL products are available on-line.

Executive Order 13101 and the Federal Acquisition Regulation also call for an increase in the federal government's use of recycled-content and environmentally preferable products. [10]

PERFORMANCE

The performance of plastic lumber depends on the type and amount of materials used and the process applied to them. The addition of wood fiber to single virgin polymers such as polypropylene (PP) and polystyrene (PS) produces a plastic composite lumber with aesthetic and mechanical properties (strength and stiffness) equal and even superior to wood lumber. [11] However, the cost of such products is higher than RPL and they consume nonrenewable resources. Increasing the amount of fiber in the composite plastic lumber improves the resistance to deformation of the product. When commingled plastics containing impurities are used, the resulting RPL does not have a homogeneous density. This may also happen to virgin materials.

Although RPL can be used in place of wood in many applications, it has different physical and mechanical properties. Time and temperature determine the properties of RPL. In general, RPL has a much lower stiffness than wood and is more prompt to deformation under sustained loads. Also the dimensional changes due to temperature are greater in RPL than in wood. Wood also experiences dimensional instability, but it is due to releasing or uptaking of water. Despite all these differences, RPL offers certain advantages over wood products. Some of these positive characteristics of RPL include:

• Rarely cracks or splinters.
• Resists rot, mildew and termites.
• Is weather and graffiti-resistant.
• Is unaffected by bacteria, worms, insects, fungi or rodents.
• Can be painted or stained when wood or other natural fiber is incorporated.
• Provides good shock-absorbing surface for pedestrian traffic.
• No waterproofing, staining or regular maintenance required.
• Is long lasting, sometimes lasting more than 50 years, depending on the application.
• Is sold in a variety of standard dimensional sizes, colors and textures.
• Is aesthetically pleasing. Can be manufactured to meet different designs and appearance specifications.

Knowledge of the mechanical properties of RPL is particularly important in construction applications. However, the lack of performance standards represented a barrier to increase the commercialization and applications of RPL. Fortunately, in 1993 the American Society for Testing and Materials (ASTM), Subcommittee D20.20.01 on Manufactured Recycled Plastic Lumber, was formed to develop test methods and specifications for plastic lumber materials. [12] Below is the list of current and proposed ASTM standards for plastic lumber:

ASTM Plastic Lumber Test Methods:

• D6108-97 Compressive Properties
• D6109-97 Flexural Properties
• D6111-97 Bulk Density and Specific Gravity
• D6112-97 Compressive and Flexural Creep
• D6117-97 Mechanical Fasteners
• D6341-98 Coefficient of Thermal Expansion
• D6435-99 Shear of Boards and Shapes
• E108 Residential Decking Flammability

ASTM Standards in Development:

• X-20-18 Polyolefin Plastic Lumber Deck Boards
• X20-28 Guide for Testing Plastic Lumber
• X20-39 Guide: Plastic Lumber Deck Construction
• X20-43 Specifications for Plastic Lumber Joists
• X20-44 Specifications for PVC Decking
• X20-41a Flexural Properties of Polymeric Piles
• X20-48 Radial Compression of Polymeric Piles
• X20-49 Specifications for Plastic Lumber in Bulk Head systems
• X20-51a Specifications Polymeric Piles for Marine Fendering
• X-XX-XX-99 Standard Specification for Marine Load-Bearing Polymeric Piles

Note: When plastic lumber is used in decking applications, the floor joists must be closer together to compensate for deformation.

AVAILABILITY

There are about 32 manufacturers of plastic wood or lumber made from recycled plastic in North America. Unfortunately very few are located in California, but many of the manufacturers have sales representatives in California. See also the Vendors and Manufacturers section below.

COST

Although the initial cost to purchase recycled plastic lumber products averages 20 percent to 50 percent more than the price of wood, payback is typically in two to four years when factoring in reduced maintenance and replacement costs. Some manufacturers assert that reducing those costs makes plastic lumber ultimately less costly than even the least expensive natural wood on the market. Many manufacturers offer free replacement for planks that crack or splinter, and guarantee their product to last up to 50 years. [13] While purchase prices of RPL are expected to decrease as technology improves and demand increases, wood prices are expected to continue to increase.

TIPS ON BUYING RPL

• Vendors typically provide installation instructions that address differences in working with plastic lumber. Purchasers are encouraged to research their options to select the product that best meets their needs. [14]
• 100 percent recycled content plastic lumber may not perform well in lengths greater than 6 feet or where deflection and creep are critical (e.g. fencing, decking, and bollards). For such uses, consider plastic lumber with fiber such as cellulose or glass. The fiber improves stability and resistance to screw pullout. [15]
• ASTM Committee D20 recommends testing the material in its original, as-manufactured state (at least, relative to the original cross-section).
• It is important to select metal-based pigments for long-term color stability. The organic pigments appear to be less stable during long-term exposure to the sun. [16]
• Request RPL that uses sodium bicarbonate and citric acid as foaming agents. The most commonly used foaming agent is azodicarbomide; however, its toxicity data has not been evaluated.
• Evaluate the toxicity of chemical additives such as flame retardants, coupling agents, metallic pigments, ultraviolet stabilizers, extrusion aids, and foaming agents.

SPECIFICATIONS

Product specifications for RPL are preferred over method or material specifications because product specifications are based on performance characteristics. Method and material specifications sometimes limit the use of recycled-content products by disqualifying recycled feedstocks or recycling-based technologies and processes.

California

The Procurement Engineering Team of the Procurement Division of the Department of General Services (DGS) develops and reviews specifications for statewide commodity standards and information technology. If you have questions regarding developing specifications, or would like a copy of one of their specifications, please contact the team. Following is a sample of DGS specifications (received October 2005) for RPL:

ASTM Specifications

Besides developing standards for plastic lumber, ASTM Committee D20 also developed purchasing and distribution specifications for RPL based on end use application and performance. The Committee developed the first specification on polyolefin-based plastic lumber decking (ASTM D6662) because this was one of the most promising markets. Manufacturers can now use an "ASTM stamp" on plastic lumber decking boards that meet the specifications. [17] During the development of ASTM D6662, several important issues concerning the performance of RPL in decking boards were resolved. The most important issues addressed in ASTM D6662 include dimensional tolerances, deflection, flammability, material properties for structural design, outdoor exposure, and slip resistance.

Commonwealth of Massachusetts

The Commonwealth of Massachusetts developed one of the most comprehensive specifications for plastic lumber. These specifications include definitions, selection criteria, bidder requirements, and products specifications by plastic lumber category, among others. All this information is part of Appendix G.1 of the Environmentally Preferable Purchasing Guide published by the Solid Waste Management Coordinating Board of Minnesota.

United States Environmental Protection Agency (USEPA)

USEPA Comprehensive Procurement Guidelines (CPG) 2002 recommend 25-100 percent postconsumer content for HDPE plastic lumber, 50 percent for mixed plastics/cellulose, 75 percent for HDPE/fiberglass, and 50-100 percent for other resins. In addition, the USEPA's Database of Environmental Information for Products and Services contains contract language, specifications, and policies created and used by federal, state, and local governments and others to buy environmentally preferable products and services.

Tips for Writing Specifications

• Use a consistent style, meaning and standard conventions for terms, abbreviations, and units.
• Avoid acronyms.
• Survey the market place to become familiar with available products and features.
• Define features quantitatively in terms of tolerances, ranges, thresholds, and limits.
• Use enforcement words "shall, must, minimum, maximum, less than, no more than, and shall not exceed" to describe required limits.
• Never over specify.
• Take into account life cycle costs of products, such as savings on maintenance, replacement, and disposal costs, which are not factored into the initial unit price.
  Example: Your evaluation criteria for bids offering plastic benches and tables could include price, durability, manufacturer warranty, required maintenance, recycled content, testing of product samples, and references.
• Write very tight specifications to control the number of voids in the lumber so that a homogenous product is obtained. RPL manufacturers can prevent the formation of voids by sorting and cleaning raw materials before extruding and forming. The California Department of Transportation (Caltrans), Office of Structure Specifications, developed specifications for plastic lumber in certain structural applications. Additional information is available on Caltrans' Web site.

VENDORS AND MANUFACTURERS

State Contracts

RPL products are available through California Multiple Award Schedules (CMAS) contracts.

Other Sources

Comprehensive Procurement Guidelines
The USEPA's list of designated products and the accompanying recycled-content recommendations provides recycled-content product information and two sources of vendors. One source is the Database of Manufacturers and Suppliers that identifies manufacturers and suppliers of plastic lumber containing recycled plastic. The second source is the GSA (General Services Administration) Advantage that lists products available through the Federal Supply Service. The GSA Advantage includes RPL.

The Environmentally Preferable Purchasing Guide
The Solid Waste Management Coordinating Board of Minnesota developed this Guide as a reference tool for government and school purchasers who want to buy more wisely. Section 8.1 lists known North American manufacturers and distributors of recycled-content plastic lumber that meet the federal procurement guidelines.

Open Directory Project
Visit the Open Directory Project Web site for a complete list of plastic lumber manufacturers in North America.

Recycled-Content Product Directory
The California Integrated Waste Management Board's Recycled-Content Product Directory contains thousands of listings of recycled-content products from thousands of suppliers.

SUCCESS STORIES

Kern County, California

In 1995, the Kern County Waste Management Department and Kern County Fair Board worked out a five-year agreement that allowed for the construction of a 2,000 square-foot fountain pavilion. Inside the pavilion, benches and picnic tables made from polystyrene lumber and recycled aluminum seat up to 100 people. Brass plates mounted on each bench and picnic table explain just how many milk jugs, plastic cups and aluminum cans went into the making of each product. [18]

King County (Washington) Environmental Purchasing Program

In 1994, the Parks Division of the King County Environmental Purchasing Program acquired 41 boards made of 100 percent postconsumer HDPE. The plastic lumber was used to replace treated wood bench slats to combat weather and vandalism. Initially it was considered an expensive project, but cost savings came from lower maintenance. It took more time to cut the plastic lumber into six-foot lengths than wood, but the installation time was the same as for wood. The Parks Division representative said he would purchase this product again because it is visually pleasing and is very versatile. Additional information about this project can be found on the King County Environmental Purchasing Web site.

Demonstration Projects

To demonstrate successful uses of RPL in structural applications and to obtain data to be used in the development of standards, five demonstrations projects were undertaken:

• Decking boards in a boardwalk at Kelleys Island on Lake Erie, Ohio;
• Bridge at Fort Leonard Wood, Missouri;
• Floating docks for the Op Sail 2000 event in New York, New York;
• Elevated platforms at the bobsled and luge track, Lake Placid, New York; and
• An arched truss bridge near Albany, New York.

Information about these projects is available on the ASTM's Web site.

City of Seattle, Washington [19]

In 1996, the City of Seattle built a recycled plastic pedestrian bridge across a stormwater retention pond. They decided to use RPL because Thorton Creek was being rehabilitated as a salmon stream.

At the time, plastic lumber was very new to the marketplace, not widely available, and did not have a long usage history. The design team had to make adjustments to their original wood design because plastic is a very different material than wood. Three different types of plastic lumber were sourced for this project:

• Recycled plastic 8"x8"s, reinforced with four steel bars (re-bar), were used for pilings and support members. The cost was approximately 1.5 times the cost of treated lumber.
• Fiberglass reinforced recycled plastic 2"x8"s were used for the joists, at a cost of about 2.7 times that of treated lumber.
• Recycled plastic/wood composite 2"x6"s were used for decking at a cost of about twice that of treated lumber.

This is probably the largest project that the City has done using RPL, but they have done several plastic lumber decking projects, park rainbow signs, truck sideboards and more.

RESOURCES AND WEBSITES

American Society for Testing Materials (ASTM)
West Conshohocken, PA
(610) 832-9585

ASTM International is a non-profit organization for the development and publication of voluntary consensus standards for materials, products, systems, and services. A December 2001 article from the ASTM Standardization News examines how standards have contributed to the growth of the recycled plastic lumber products industry.

California Integrated Waste Management Board (CIWMB)
Sacramento, CA
(916) 341-6000

The CIWMB's mission is to reduce waste, promote the management of all materials to their highest and best use, and protect public health and safety and the environment, in partnership with all Californians. The CIWMB is actively working toward developing more comprehensive solutions for managing plastic materials, and to mitigate for the adverse environmental impacts associated with plastic discards. For more information, visit the CIWMB's Plastics Information and Resources Home Page.

King County Environmental Purchasing Program
Seattle, WA
(206) 296-0100
(800) 325-6165

A pioneer and contemporary model in environmental procurement, King County offers on its Web site procurement case studies for a variety of products including recycled plastic lumber, along with resources for environmental purchasing and waste reduction. The December 2003 report, "Plastic 'Lumber' and Other Recycled Plastic Products", discusses the county's experiences with procurement, bid and contract specifications. The county maintains an extensive vendor list.

Minnesota Pollution Control Agency (MPCA)

St Paul, MN
(651) 296-6300
(800) 657-3864

The MPCA is a state agency that provides information, assistance, grants, and loans in the areas of waste, pollution prevention, recycling, reuse, and environmental education. The MPCA's Web site houses many resources on recycled plastic lumber, including a vendor list, success stories, detailed product characteristics, and information about the ASTM standards.

National Recycling Coalition's Buy Recycled Business Alliance (BRBA)
Washington, DC
(202) 789-1430

The BRBA is a broad-based group of companies and nonprofit organizations committed to increasing the purchase of recycled-content products.

Plastic Lumber Trade Association
Akron, OH
(330) 762-1963

The Plastic Lumber Trade Association promotes the engineering, art and science, marketing and procurement of recycled plastic lumber and related products. The association's Web site contains downloadable annual reports on the "State of Recycled Plastic Lumber".

Recycled Plastic Products Directory
Arlington, VA
(800) 2-HELP-90

The American Plastics Council, a trade association for plastics manufacturers, maintains a Web site containing information on recycled-content plastic products such as lumber and decking, as well as information on recycling plastics. The council's national vendor database lists over 30 manufacturers of plastic lumber and specifies the level of postconsumer content in their products.

Residential Environmental Design

Residential Environmental Design, a Web site supporting the advancement of green architecture, offers reviews of vendors of recycled-content decking.

United States Environmental Protection Agency (USEPA)
Washington, DC
(202) 272-0167

In order to assist federal agencies in purchasing environmentally preferable products and services, the USEPA offers a range of public information about products such as recycled plastic landscaping timbers and posts. Visit the USEPA's Comprehensive Procurement Guidelines (CPG) Web site for its Recycled Material Advisory Notices (RMAN), which recommend recycled-content levels. Since 2004, the USEPA has offered downloadable fact sheets for that summarize CPG information, USEPA's recovered materials content recommendations, case studies from around the country, and key resources, associations, and Web sites.

[1] State of California. California Integrated Waste Management Board. 2003 California Waste Characterization Study. Available at www.ciwmb.ca.gov/plastic/.

[2] Prabhat Krishnaswamy and Richard Lampo. "Recycled-Plastic Lumber Standards: from Waste Plastics to Markets for Plastic-Lumber Bridges." ASTM Standardization News. December 2001. pp. 26-31.

[3] The American Plastics Council. Recycled Plastic Lumber. Available at www.plasticsresource.com/s_plasticsresource/sec.asp?TRACKID=&SID=4&VID=46&CID=128&DID=230.

[4] Ibid.

[5] The Plastic Lumber Industry in Competitive Markets. 2001-2002 State of the Recycled Plastic Lumber Industry. Presented by Alan E. Robbins. Annual Meeting of the Plastic Lumber Trade Association. March 11, 2002, Pittsburg, Pennsylvania.

[6] Solid Waste Management Coordinating Board of Minnesota. Environmentally Preferable Purchasing Guide. Section 8.1 Plastic Lumber. Available at www.greenguardian.com/EPPG/8_1.asp.

[7] United States Environmental Protection Agency. 2004 Comprehensive Procurement Guidelines Buy-Recycled Series Park & Recreation Products Fact Sheet. Available at www.epa.gov/cpg/factshts.htm.

[8] From California Integrated Waste Management Board staff communication with Office of the Federal Environmental Executive staff on December 12, 2005.

[9] United States Environmental Protection Agency. 2004 Comprehensive Procurement Guidelines Buy-Recycled Series Park & Recreation Products Fact Sheet. Available at: www.epa.gov/cpg/factshts.htm.

[10] Ibid.

[11] Environment and Plastics Industry Council (EPIC). Recycled Plastic Lumber. A Strategic Assessment of its Production, Use and Future Prospects. Report prepared by David Climenhage, under contract, for the Environment and Plastics Industry Council. January 2003, p.2.

[12] Prabhat Krishnaswamy and Richard Lampo. "Recycled-Plastic Lumber Standards: from Waste Plastics to Markets for Plastic-Lumber Bridges." ASTM Standardization News. December 2001. Available at www.astm.org/SNEWS/DECEMBER_2001/wsd_dec01.html.

[13] Solid Waste Management Coordinating Board of Minnesota. Environmentally Preferable Purchasing Guide. Section 8.1. Available at www.greenguardian.com/eppg/8_1.asp.

[14] Minnesota Office of Environmental Assistance. Plastic Lumber. Available at http://www.pca.state.mn.us/oea/epp/plasticlumber.cfm.

[15] National Institute of Building Sciences. Draft Federal Guide for Green Construction Specs. Sponsored by the United States Environmental Protection Agency. Available at www.wbdg.org/design/greenspec_msl.php?s=06600.

[16] Environment and Plastics Industry Council (EPIC). Recycled Plastic Lumber. A Strategic Assessment of its Production, Use and Future Prospects. Report prepared by David Climenhage, under contract, for the Environment and Plastics Industry Council. January 2003, p. 17.

[17] Prabhat Krishnaswamy and Richard Lampo. "Recycled-Plastic Lumber Standards: From Waste Plastics to Markets for Plastic-Lumber Bridges." ASTM Standardization News. December 2001. Available at www.astm.org/SNEWS/DECEMBER_2001/wsd_dec01.html.

[18] California State Association of Counties. Kern County. Fair Pavilion Project. Available at www.csac.counties.org/default.asp?id=582.

[19] King County (WA) Environmental Purchasing Program. Plastic "Lumber" and other Recycled Plastic Products. Recycled Plastic Pedestrian Bridge, City of Seattle. Available at www.metrokc.gov/procure/green/plastic.htm#3.

Special Note: Portions of the Environmentally Preferable Purchasing Best Practices Manual were borrowed or adapted from the Environmentally Preferable Purchasing Guide published by the Solid Waste Management Coordinating Board of Minnesota.