Data Sources and Data Base

4. DATA SOURCES AND DATA BASE This section describes the data base that has been assembled for this study. It outlines the information the data base contains for the common strategies and the ways in which it can be used. Technical details on operating the data base, understanding the relationships between the worksheets, and changing data base assumptions are presented in the data base user guide in Exhibit II. The data base was constructed in Lotus 1-2-3, and an electronic version is available that can be customized to suit local conditions or to incorporate different data or assumptions. Exhibit II also provides a copy of the structure and contents of the data base. The information on the less common strategies that is included in the data base is discussed in Chapter 9.

PURPOSE OF DATA BASE

The data base provides quantitative data on the energy and emissions from the individual solid waste management technologies covered in this report; it also offers the option of determining the total energy and emissions for a strategy that incorporates any number of the individual technologies. (In this report, the term "strategy" is used to refer to the combination of technologies that a community uses to manage its MSW.) Because the characteristics of individual communities and regions (e.g., percentages of waste handled through curbside collection of recyclables, proximity of landfill) are often significantly different, the data base allows modifications of key assumptions. Instructions for customizing the data base are included in Exhibit II.

STRUCTURE OF THE DATA BASE

The data base has two parts. The first presents data on each individual technology. The common technologies covered in the data base are listed in Table 4.1.

The second part of the data base combines technologies into strategies. For example, a strategy could include the collection and transportation of MSW from the curb to a landfill, plus landfilling with gas recovery. Another example would be the collection of reusable materials with processing in a materials recovery facility (MRF), plus the collection, transportation, and landfilling of the remaining MSW.

More complex strategies can also be considered. For example, in a community that prepares refuse-derived fuel (RDF) for direct combustion, the strategy could include collection and transportation of mixed MSW, plus RDF preparation with separation of recyclables, plus landfilling a portion of the MSW that is not used as fuel, plus RDF combustion, plus separate land filling of the ash. The data base combines these technologies in the correct proportions and computes the overall energy requirements and emissions for the strategy as a whole. Table 4.2 lists the terms used in the data base for the strategies for which such calculations have been performed. Figure 4.1 illustrates the common strategies that use only the five major technologies covered in Sections 5 through 8.


                                                    Table 4.1
                                      COMMON TECHNOLOGIES IN THE DATA BASE


          Collection and transportation of MSW in a packer truck
          Collection and transportation of curbside-separated yard waste in a packer truck
          Collection and transportation of curbside-separated recyclables in a multi-compartment truck
          Landfill operations
          Ash monofill operations
          Material recovery facility (MRF) operations and remanufacture of the collected materials(a)
          Mass burning
          RDF preparation and metal recovery
          RDF combustion
          Yard waste composting
          MSW composting

          (a) The data base provides only energy data for remanufacture of collected materials.





                                                    Table 4.2
                                       COMMON STRATEGIES IN THE DATA BASE

       1  Landfill with gas recovery
       2  Mass burn plus ash landfill
       3  Onsite MRF plus mass burn plus ash landfill
       4  RDF for direct firing plus landfill
       5  Yard waste composting plus landfill
       6  Curbside MRF plus landfill
       7  Curbside MRF plus mass burn plus ash landfill
       8  Curbside MRF plus RDF for direct firing plus landfill
       9  Curbside MRF plus RDF for composting plus landfill
      10  Curbside MRF plus landfill plus yard waste composting
      11  Curbside MRF plus mass burn plus yard waste composting plus ash landfill

Click here for table in WK1 format.

Figure 4.1
STRATEGIES BASED ON THE FIVE MAJOR OPTIONS

Click here to expand figure.

Figure 4.1
STRATEGIES BASED ON THE FIVE MAJOR OPTIONS (Concluded)

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Information Provided

The data base contains separate worksheets that characterize either a specific technology or a combination of technologies. The technologies are characterized in terms of "Inputs" and "Outputs."

The common inputs include:

Raw materials (e.g., MSW, feed)
Water
Energy required

The common outputs include:

Energy produced
Net energy
Air emissions (quantity of each chemical compound)
Leachate (quantity of each chemical compound)
Solid waste (weight, volume)
Recyclable products (net energy saved).

Limitations of the Data Base

The data base is primarily designed to provide consistent data on individual technologies and to integrate those technologies into strategies; it should not be extended beyond its original intent. For example, the data base is not designed to:

Predict future growth rates of MSW
Predict amount or composition of MSW
Optimize or integrate collection routing for MSW pickup or curbside collection
Account for energy impacts or raw material impacts when a recycled material is used for applications other than its original use(1)
Correlate MSW generation or composition with demographic variables, socioeconomic class, proportion of single-family homes or apartment houses, or any other factor(2).

Data Source and Assumptions

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