MIXED WASTE PROCESSING OPTIONS

4.3.1 Existing Conditions

Mixed waste processing systems range in complexity from simple “dump-and-pick” operations to highly mechanized facilities.

With dump-and-pick operations, recovery is typically limited to larger items that are easily removed (such as cardboard boxes and scrap metal). In this case, the primary requirement is simply that the disposal facility must have a tipping floor to allow loads of waste to be dumped out of collection vehicles onto a flat surface, ideally with space to spread out each load to allow access to all sides of it. A forklift or other equipment is also necessary for moving and emptying the containers used for temporary storage. Other requirements include additional labor to pull out materials plus containers for both temporary and long-term storage of the recovered materials. Dump-and-pick operations may create a situation where workers have extensive contact with raw garbage, with the subsequent risks to their health.

The County, SWAC and recycling contractor have all expressed interest in implementing a dump- and-pick operation at the Transfer Station. This operation would target recyclable materials that could be diverted from the waste stream prior to the loading of the trailers. Previous discussions have also included the possibility of recovering reusable items, such as furniture, appliances, bicycles and toys, tools, and lumber scraps. Transfer Station personnel or others could recover these items for giveaway or resale. No salvaging by the public would be allowed. Currently, the only materials that are recovered in this manner are ferrous metals.

4.3.2 Needs and Opportunities

A mixed processing system could recover additional amounts of recyclable and reusable materials. Data from waste composition studies in other areas indicates that between one-third and one-half of the waste stream is made up of recyclable materials. Data from a recent waste composition study conducted for Snohomish County (GS 1998) shows that the waste stream for that county contains 3.7% (by weight) of reusable materials (materials that could be directly used for their original purpose). The major components of the reusable materials found in Snohomish County included wood building materials (20.6% of the total), large pieces of carpet (16.2%), new asphalt shingles (11.7%), and various metal objects (11.0%), with the remainder made up of furniture, special wastes, plastic products, soil, clothing, and miscellaneous other materials.

A mixed waste system that processes solid waste would require significant capital investment, but a dump-and-pick operation would not require as large of an investment in equipment.

4.3.3 Alternative Methods

Dump-and-Pick Operation

Pursing the idea of a dump-and-pick operation would require a careful examination of the

operational issues for the various options, as well as examining the overall feasibility (particularly on a cost-benefit basis).

Operational issues for a dump-and-pick operation include:

➤ Staffing: More workers would be required on-site at the Transfer Station, but these could be County staff or private employees.

➤ Location: A central location for picking operations would be required. If a “resale area” were to be considered a part of the operation, it would need to be well separated from the tipping floor of the Transfer Station for safety reasons.

➤ Proceeds: Materials removed from the waste stream could be given away or sold. Monies collected through this program could be used to offset recycling program costs and to promote the resale program. Another option would be to contract the reuse operation to a private entity, and allow that entity to keep any net profits.

➤ Markets: The success of the area’s many thrift stores and the ongoing interest in the County sponsored SWAC/SWAP event demonstrate the interest in reuse by the citizens of Jefferson County. A similar program, in fact, existed in the late 1980s, but was closed for economic reasons when the recycling picking line conveyor was installed inside the Recycle Center. ➤ Liability: Issues of liability and associated costs may make it difficult to establish a dump-and-

pick operation at the Transfer Station. The County and City’s legal counsels should consider this issue.

Mixed Waste Processing

Mixed waste processing requires a facility or system that is designed to accept garbage and process it to remove the recyclable materials. Processing typically includes a combination of mechanical systems, which are effective at removing only certain materials, and manual sorting. Mixed waste processing could be used in place of source separation, although often it is used in addition to traditional recycling programs to remove materials remaining in the waste stream. Mixed waste processing is also used with a co-collection program, where recyclables are placed in special bags that are then recovered at a central facility (see Section 6.2.3 for more information on co-collection methods).

In the case of highly mechanized facilities, a great deal of capital equipment (trommel screens, conveyors, air classifiers) and manual labor is used to remove a wider range and greater amount of recyclable materials. A typical facility might include a tipping floor for removing bulky and other non-processible materials, trommel screens (a rotating drum with one or more sizes of holes in the side) and/or air classifiers for the initial separation of waste components, a picking line for

manually removing materials, and conveyors to link these elements together. The materials recovered from this type of facility may be lower in quality (dirtier) than source-separated

recyclables, and the economics of this approach may hinge on the availability of a waste-to-energy plant to purchase the light residuals (non-recycled paper and plastic) as a fuel.

A study conducted for Port Angeles (Parametrix 1993) concluded that mixed waste processing was close to being economically competitive (at $93 to $95 per ton) with other solid waste handling options and could divert approximately 30% of the waste stream. This analysis assumed the remaining waste would be exported and that other recycling programs in Clallam County would be cancelled (existing recycling would be replaced by a central recovery facility, and the cost savings

however, this type of facility has been proven to be a riskier venture than once thought (several similar facilities have failed) and waste export costs have proven to be significantly lower than projected. Furthermore, there would be lower economies of scale in Jefferson County than in Clallam County due to lower quantities of waste and recyclables, and so the cost per ton for capital-intensive approaches such as mixed waste processing would be higher. A regional approach (combining the waste streams of both Jefferson and Clallam Counties) would lead to lower processing costs, but transportation costs to ship both counties’ wastes to a central location may equal or exceed any processing cost savings.

In any case, waste processing can be a relatively expensive and risky approach for recovering recyclable materials, and so it is usually not pursued unless there is a strong mandate for increased recycling or very high disposal fees (i.e., a high potential for avoided costs). If part of the facility or equipment is already available, however, then mixed waste processing may be more feasible.

4.3.4 Recommendations

The following recommendation is made for mixed waste processing activities in Jefferson County: R6) The County should continue to evaluate the possibility of using staff or contracted

employees to pull recyclable and/or reusable materials from the solid waste after it is dumped on the floor of the Transfer Station.

4.3.5 Implementation Schedules and Costs

This is a low-priority recommendation that would need to be refined at a later date if implemented. If implemented, costs could include staff time for contracting and monitoring, additional staff, capital improvements (modifications to the transfer station, construction of a storage facility, conveyor systems, and/or other alterations), equipment (small loader, forklift, and/or trucks for transporting materials), insurance, and other costs.

CHAPTER 5: COMPOSTING

5.1 INTRODUCTION

The solid waste management activities discussed in this chapter are organized into three sections based on the type of material to be composted: