Although source reduction, recycling and composting will continue to lessen the overall amount of municipal solid waste (MSW), certain wastes always will require disposal.
Based on their environmental safety, known technologies and daily management practices, landfilling and waste to energy (WTE) are the nation's favorite disposal methods. Rural communities' disposal options include Subtitle D or inert landfills; WTE technologies such as refractory mass-burn, waterwall mass-burn and modular mass-burn; or refuse-derived fuel (RDF) facilities. Advantages and disadvantages will vary for each (see charts below and on page 71).
For WTE to be economically feasible for rural areas, a nearby reliable energy market must exist and sufficient solid waste quantities must be available at a reasonable de-livery cost. For this reason, landfilling is chosen more often by rural communities. To select the appropriate facility for rural, re-gional MSW disposal, use the following steps as a guide.
Of course, selecting constructing and finally operating any disposal facility is no simple task. It can take several years of careful research and diligent politicking to complete the project.
1 Conduct A Waste Stream Study A waste composition study will determine the region's present and projected MSW composition and quantity. Regional waste stream characteristics will determine feasible waste reduction strategies such as source reduction, recycling and composting. Next, estimate the amount of waste requiring disposal over a 10-year planning period.
2 Evaluate Remaining Disposal Capacity Identify remaining disposal capacity as well as facilities that will close during the upcoming 10-year period.
Determine capacity by comparing state landfill design volume to weight estimates for solid waste requiring disposal. Many states require lifetime estimates based on the facility's original design - not on daily use.
However, design capacity is not a good gauge of a facility's life; in fact, some daily use policies can fill in five years of a landfill that was initially de-signed for 20.
Other factors to consider when evaluating remaining capacity include:
* use rate (accepting more waste than planned will shorten a facility's life);
* hours of operation (shortened daily or weekly operation hours may extend facility life);
* state and federal requirements for permits, operations and environmental controls;
* proper management practices (unacceptable practices can cause facility closure);
* changes in the material types accepted (banning high-weight and high-volume materials such as yard waste and construction and demolition (C&D) wastes provides additional space for other MSW);
* local decisions regarding continued public ownership and operation of existing facilities; and
* operating costs (some localities may decide to save money by closing a facility before it reaches capacity).
If local governments are using private landfills, determine how long these facilities will be used. Remember that private facilities may accept out-of-state MSW; states often only require reports of in-state tonnages.
Lack of import data can significantly affect calculations of remaining landfill capacity. Acquiring information for private landfills can be difficult because reporting capacity may not be required and is confidential.
3 Develop Evaluation Criteria Organize an advisory group to assist in identifying key factors for disposal alternatives. The advisory group should represent a range of interests and varied backgrounds. The following may be considered when developing your evaluation criteria: cost effectiveness; time frame; reliability; environmental impact; adaptability; financing requirements; regional application and transportation; ability to meet regulatory requirements; local conditions; public acceptance; and basic siting requirements.
Applying these criteria will help to evaluate the strengths and weaknesses of the disposal technology under consideration. Summarize each alternative's ability to meet the criteria.
4 Identify Alternatives Use the criteria to analyze each alternative to determine how well it will meet the region's disposal needs. This preliminary selection will narrow the list of alternatives that can be studied in greater detail, including engineering and cost analyses.
Rural disposal alternatives include:
* Subtitle D landfill. Often this option is too expensive for a rural community unless its costs are shared with others in the region. Factors local governments should consider before choosing this option include transportation costs to centralized facilities, legal ability, environmental equity, participation costs and community preferences.
* Inert solid waste landfill. Inert landfills only accepts materials such as rocks, concrete, asphalt, bricks, and tree, shrub, yard and C&D wastes, all of which are not likely to produce leachate harmful to groundwater. These materials can compose 20 percent by weight of the solid waste stream (higher percentages for areas with heavy construction). Siting, design, construction and daily operation are based on individual state requirements. In states where regs are easily implemented, an inert landfill network can be a useful part of a region's disposal system.
* WTE Technologies. These options can be used in conjunction with source reduction, recycling and composting programs. To be successful, WTE facilities need a continuous solid waste supply and long-term (usually 20 years) contracts with reliable customers for the steam and/or the electricity produced. For political and economical reasons, these methods must be thoroughly considered. WTE systems include:
* Refractory mass-burn. This method combusts unprocessed MSW. Two separate systems remove fly ash and bottom ash from the combustion process. Bottom ash is disposed in a lined landfill.
* Waterwall mass-burn. This technology differs from refractory in its heat collection method. It uses water to cool the furnace during the combustion process which decreases the need for a protective refractory furnace lining. This process heats water in boiler tubes, producing steam which can be used to generate electricity - both of which can be sold.
* Modular mass-burn. This option uses combustion units that are smaller than mass-burn plants. These facilities often serve small- to medium sized communities, industries or institutions such as hospitals.
* Refuse Derived Fuel. RDF pellets are developed through mechanized grinding and screening. These facilities are not economically feasible if long term fuel contracts are not secured or where other fuel sources are readily available.
5 Analyze The Sites Choosing an appropriate site for a disposal facility is complicated and often time consuming. The location must meet the siting criteria, satisfy state and federal requirements, have minimal environmental, cultural and historical impacts and be publicly acceptable. (See "10 Steps To Successful Facility Siting," World Wastes, May 1996, pages 78-86.)
Selection involves evaluating potential sites and eliminating areas on or near airports, floodplains, wetlands, seismic impact zones, etc.
A siting committee can develop additional criteria such as land use compatibility; hauling distance to the facility; existence of natural buffers between the public and the facility; present and future population density; perceived impact on property values; presence of threatened or endangered species; ground and surface water protection; and perceived risk. For successful siting, be sure to involve the public fully and early in the process.
6 Analyze Finances Total cost and the ability to finance a disposal option are often the deciding factors. The final cost analysis should be completed by a consultant specializing in environmental engineering and financial analyses.
The consultant can recommend fi-nancing methods and assess the affordability of each alternative for the region. The consultant will recommend the best alternative(s) for the region based on environmental suitability, cost, financing and engineering analyses.
7 Select A Disposal Method Local elected officials should select and implement the appropriate disposal method. Citizen approval will often dictate the final choice. Therefore, it is imperative that citizens be actively involved throughout the facility planning process. (See "Don't Wait To Educate Residents About MSW Plans," in the August 1995 issue of World Wastes for several effective public involvement methods.)
The answers to the following questions can assist rural communities as they consider disposal alternatives:
* What population size is expected to use the facility?
* How much municipal solid waste (MSW) will be disposed at the facility?
* What is the estimated tipping fee?
* Who will own and operate the facility?
* What are the financing options?
For a regional Subtitle D landfill: * Is environmentally suitable land available for siting a landfill?
* Can a centralized facility economically serve all areas in the region?
For an inert landfill: * How do state regulations define an inert landfill?
* How much material can be disposed in an inert landfill?
* Do state regulations require complex design and environmental control standards?
For a waste-to-energy facility: * What is the regional energy demand?
* Is there a long-term, steady market for the energy?
* What state regulations are waste-to-energy (WTE) plants required to meet for ash disposal? Can the ash be disposed with MSW or must it be placed in an ash monofill?
* How will the cost of meeting air quality standards affect tipping fees at the facility?
* Will a WTE facility cost significantly more than a Subtitle D landfill?