1. GIS APPLICATIONS IN SELECTION OF SOLID WASTE DISPOSAL SITES

2. ADVANTAGES OF GIS:
Geographic Information System ( GIS ) is a very helpful tool that integrates a variety of information by graphics
It can let us integrate many kinds of information through graphical interfaces.
GIS can also answer more complicated questions, as, for example, using models to evaluate health risk and the trend in environmental quality assessment, and determine the priority area for development based on the degree of environmental sensibility.

3. GIS DATA STORAGE
In order to apply GIS to process a variety of different types of analyses, we have to ensure that GIS data are properly stored, easy to retrieve and modify.
Traditionally, when utilizing GIS, one classifies data into Graphic Data and Attribute Data. Graphic Data are large in quantity and contain few changes; and usually Attribute Data are large in quantity and highly changeable. Therefore, these two types of data are stored in different databases.

4. GIS DATA STORAGE
the Graphic Database is divided into three categories:
1. Vector Data: Most data related to the environment have the characteristics of spatial distribution and geographic location
2. Satellite Data: Satellite image data obtained by the remote sensoring process possess the characteristics of broad coverage and multi-temporal photography.
3. GPS ( Global Positioning System ) Data: It can be applied to different spatial positioning of important landmarks, such as factories, industrial zones, disaster areas and water supply districts, etc

5. Decision Making
(Reference: James C. Ascough II, USDA-ARS, Great Plains Systems Research Unit)
Decision makers historically have indicated that inaccessibility of required geographic data and difficulties in synthesizing various recommendations are primary obstacles to spatial problem solving
Studies have shown that the quality of decisions (i.e., the ability to produce meaningful solutions) can be improved if these obstacles are lessened or removed through an integrated systems approach, such as a spatial decision support system (SDSS).
In addition, multicriteria decision making (MCDM) and a wide range of related methodologies offer a variety of techniques and practices to uncover and integrate decision makers’ preferences in order to solve “real-world” GIS-based planning and management problems.

6. Landfills
(Reference: Herzog and Labadie (2000))
GIS helps in the development of a suitable DSS for siting the new landfill.
First phase: Screening
uses exclusionary criteria to eliminate sites with legal
restrictions, physical impracticalities, potential threats to public water
supply and environmentally sensitive areas, proximity to residential areas, and overlying geological fault zones.
Second phase: MCDA
Potential sites were ranked using multi-criteria decision analysis (MCDA) algorithms and non-exclusionary data such as soil suitability, habitat effect, flood resistance, property costs, distance from population center, and hauling distance. Sensitivity analyses can be performed rapidly to assess how assigned weights affect the outcome. The results of the MCDA and the decision-making process can be demonstrated and displayed with GIS to diminish environmental.

7. Using GIS for Determining Potential Low Level Hazardous Waste Disposal Sites in North Carolina
The process of siting a hazardous waste landfill (or for that matter any landfill) is a long political process that is subject to many changes in variables. By employing GIS in this selection process it may become easier to develop a preliminary coverage of potential sites.
This coverage would be based on regulated restrictions and may help lessen the bias towards siting in areas of lower economical and political prominence
GIS would allow the analysis of site selection to include an optimization of viable sites subject to the variables of interest

8. Method for Conducting Project
Research the North Carolina criteria for selecting potential sites
Obtain coverage data that corresponds to the NC criteria (such as soil types)
Use ArcInfo/ArcView to create a series of layouts that select potential sites by a process of elimination

9. The process of creating exemption coverages
The process of creating exemption coverages was repeated for the following:
Road Coverage with 300 meter buffer
Stream Coverage with 90 meter buffer
Wetland Coverage (Landfill can not sit in wetland)
Urban Coverage (Landfill can not sit in urban areas)
Flood Prone Coverage (Landfill can not sit in flood prone areas)
Cost coverages

10. Cost coverages
The cost coverages created consisted of two sets of more restrictive coverages, including land areas with very low clay contents (<10 %) and areas with moderately low clay contents (<30%). The theory behind this selection criteria was that clay materials are very impermeable and thus tend to restrict pollutant migration. In addition, clays are used in landfill construction and the presence of on-site clays reduce the cost of landfill construction.

19. Conclusions:
The results from the preceding project illustrate the impact that GIS can have on siting problems. By providing an unbiased methodology and the ability to optimize and change relevant variables, GIS is a useful tool in solving such problems. As more data becomes available, the usefulness and accuracy of this tool will only increase.