The University of Akron Department of Geography and Planning Landfill Site Suitability Analysis for Non-toxic Solid Waste in Puerto Rico - A GIS Approach- Agustín B. Graterole Applications in GIS and Cartography Agustin B. Graterole Page 1 8/19/2008
INDEX 1. Introduction 3 2. Objective 4 3. Study Area 5 4. Methods and Analysis 7 a) Exclusion Areas Map 7 b) Site Suitability Model 10 i. Surface to Ground Water, Rivers and Streams, and Lakes 11 ii. Lineament Zones 16 iii. Land Use/Cover 17 iv. Slope 18 v. Urban Areas 19 5. Results/Conclusion 21 6. References 25 Agustin B. Graterole Page 2 8/19/2008
Introduction One of the most challenging environmental issues for the island of Puerto Rico is the management of non-toxic solid waste. With an increasingly dense population and a current shortage of places to dispose non-toxic solid waste properly, the island faces a huge environmental problem. During the early industrial development of Puerto Rico (1950 s), sub-standard and clandestine landfills were created. These landfills failed to meet the Environmental Protection Agency s (EPA) standards in terms of structural quality and appropriate location. One negative effect was the pollution of superficial and ground water resources on surrounding areas. Since 1994, the EPA ordered the closure of 34 out of the 62 landfills that were in operation. Most of the 28 landfills that were left are expected to close by 2018 and it is estimated that the disposal capacity of current landfills will be less than the amount of waste that will be generated (Vicenty 2004). Although policies such as recycling, reduction and reusing are expected to be implemented at a larger scale, disposal of the remaining non-toxic solid waste in landfills is still going to be necessary to meet future demands. Agustin B. Graterole Page 3 8/19/2008
Objective The objective of this research is to determine and analyze suitable areas for the location of landfills in Puerto Rico with the use of Geographic Information Systems software. Criteria for their localization will be: Low environmental impact. Low human health impact. The final objective is to identify areas large enough for disposing the quantity of non-toxic solid waste that will be generated in the future. Agustin B. Graterole Page 4 8/19/2008
Study Area The study area for this research is the island of Puerto Rico. Puerto Rico is located in the Caribbean at 18 15 N and 66 30 W. It is composed of the main island and other smaller islands, some of them are part of the 78 municipios like Vieques and Culebra. However, for the nature of this research, the study area will be the main island which is composed by 76 municipios. Puerto Rico as a whole has a total area of 3,515 square miles (9,104 sq/km). The maximum length from east to west is 111 miles (178 km) and the maximum width from north to south is 40 miles (64 km). The main island is mostly mountainous with large coastal areas on the north and south. It has an extensive inner mountain range called "La Cordillera Central" (The Central Range). Up to 75% of the mainland is mountainous with it highest peak reaching 4, 390 feet (1,338 m), called Cerro de Punta. Steep slopes and streams dominate large amounts of the mainland territory which causes difficulty for the appropriate location of non-toxic solid waste landfills. The large valley type coastal areas to the north and south of the island make up only 25% of the mainland. A significantly large portion of this area on the north is made of karsts limestone rocks which are permeable to water and pollutants. The karstic region of Puerto Rico which is one of the biggest in the earth is on top of numerous aquifers used by the population to extract water. Agustin B. Graterole Page 5 8/19/2008
Feet 4,361-47.5065 Agustin B. Graterole Page 6 8/19/2008
Methods and Analysis This research is divided into two sections: I. Development of Exclusion Areas map II. Creation of a Site Suitability Model based map Exclusion Areas In 1990, the Autoridad de Desperdicios Solidos of Puerto Rico (ADS) (Puerto Rico Authority of Solid Waste) mapped areas of exclusion for non- toxic solid waste landfills. This was an effort to identify unsuitable areas in which some landfills were constructed in the past in Puerto Rico. For this map, the criterion used was established in Subtitle D of the Resource Conservation and Recovery Act (RCRA). For determining the areas for exclusion in 1990, the following factors were included: Exclusion Areas 1990 Environmental Related Factors Human Related Factors Flood Areas (100 year recurrence) Urban areas High Density Forests Buffer Zones around Airports Reserves Historic Places Wetlands Cultural Places Lakes Karstic Regions Habitat of Endangered Species Agustin B. Graterole Page 7 8/19/2008
A map which would determine unsuitable places for the location of non-toxic solid waste landfills in Puerto Rico was reconstructed for the purpose of this research. This map is named Exclusion Areas 2008. It was developed using a wide range of data sets and previously used criteria from the RCRA. However, other new and updated criteria were added, making it more comprehensive and updated than the 1990 version. This new maps development was facilitated by using Geographic Information Systems (GIS) procedures such as digitizing, uniting layers, creation of new feature data layers, geo-processing techniques such as buffers and overlay, and Spatial Analyst tools like Slope. Both raster and vector data layer formats were utilized. The following factors were added to the Exclusion Areas map: Exclusion Areas 2008 (Current Research) Environmental Related Factors Human Related Factors Steep slopes ( >20 degrees) Urban Areas (2000) Mineral Formation Areas Lineament zones Main Aquifers Rivers and Streams Medium Density Forests Public Areas Leisure/Recreational Areas Cultivated Agricultural Land Mining Areas Principal Roads Agustin B. Graterole Page 8 8/19/2008
Map: 2008 Exclusion Areas Map Agustin B. Graterole Page 9 8/19/2008
Site Suitability Model Places that are outside the Exclusions Areas map will be considered for identifying suitable locations for non-toxic solid waste landfills. Since these residual areas vary in degree of suitability for locating landfills, a Site Suitability Model was created to identify the most ideal places. An example of degree of suitability is proximity to water resources and/or type of land cover in different areas. The following six factors and their criteria were applied for the model: Site Suitability Model Factor Criteria 1. Surface to Ground Water Depth from Surface and Ground Water 2. Rivers and Streams Proximity to Rivers and Streams 3. Lakes Proximity to Lakes 4. Lineament Zones Proximity to Lineament Zones 5. Slope Steepness of Slope 6. Land Use/Cover Type of Land Use and Land Cover 7. Urban Areas Proximity to Urban Areas of 2000 Agustin B. Graterole Page 10 8/19/2008
Surface to Ground Water, Rivers and Streams, and Lakes A negative impact that non-toxic solid waste landfills pose to the environment is the contamination of surrounding water resources. A leachate is a liquid that drains or 'leaches' from a landfill. Leachates vary widely in composition regarding the age of the landfill and the type of waste that it contains. It can usually contain both dissolved and suspended material. This pollutant can travel downward through the ground toward aquifers and/or to bodies of water like lakes and rivers. Past landfills that were constructed in Puerto Rico caused this significant environmental impact on the island s water resources. The Surface to Ground Water layer takes into consideration underground water bodies like aquifers. To create a Surface to Ground Water map of the island, data from the island s existing wells was used. A point shapefile data layer that contained the location of wells and their depth to water was used to create a Surface to Ground Water Depth map. This was possible using the Inverted Weighted Distance Technique (IDW). More than 2,500 wells were used to develop this IDW. The wells range from 0 to 2,100 feet in terms of depth. Since terrain elevation in the island often reaches higher than 2,100 feet on the mountainous region, terrain elevation higher than 2,250 was taken out of the IDW calculation to depict a more realistic Surface to Ground Water value through out the map. This depth to water IDW raster layer was reclassified into four classes. It is important to know that 93.4% of the wells had less than 100 feet from surface to ground water. Agustin B. Graterole Page 11 8/19/2008
Modern non-toxic solid waste landfills contain liners on the ground for mitigating the effect of the leachates. Their purpose is to prevent the pollutant s downward movement into the ground from the landfill. However, these liners often fail to contain the pollutant. In regard to surface to ground water depth, the deeper the water is, the lower the probability of ground water contamination. In the table below, increase in depth is also an increase in suitability value. Agustin B. Graterole Page 12 8/19/2008
Puerto Rico is covered with vast amounts of rivers and streams. These originate on the center of the island because of the topography on the Central Range region. The quantity and complexity of elevated areas plus the considerable amount of rainfall in the Central Range region, produces a great variety of streams that are evenly spread around the island s territory. This topography also permitted the creation of artificial lakes. Suitable locations for landfills are scarce because of these vast amounts of water bodies, especially rivers and streams. All rivers, streams and lakes from the original shapefile layers were buffered with a distance of 100 feet. This newly created shapefile was the one to be used for constructing the Exclusion Areas 2008 map. By doing this, any geographic errors from the original shapefiles were minimized in terms of the location of the water bodies. In the Site Suitability Model, the farther away from these water bodies the higher the suitability for that area. The highest suitability values are for areas farther than 1,000 feet. The idea is that liquid pollutants that originate from landfills will have a lower probability of contaminating a water body the farther it is from it. This Site Suitability Model includes distance from rivers, streams and lakes combined with null slopes to help minimize the probability of pollutants from reaching the island s water resources. However, it is important to note that a distance of 1,000 feet from water bodies, urban areas, etc., is not the most ideal distance to locate landfills. The table below illustrates the suitability values assigned for the other proximity classes of both River and Streams, and Lakes: Agustin B. Graterole Page 13 8/19/2008
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Lineament Zones Lineament Zones is a geologic formation taken into consideration for the Site Suitability Model because of the threat of contamination of ground water systems. Lineament Zones were identified by P. Briere (1999) with the help of a Side-Looking Airborne Radar image from Puerto Rico. Lineament Zones are natural geologic formations in which water easily percolates through the ground, therefore threatening ground water sources. These zones were included in the Exclusion Areas map and for the purpose of the Site Suitability Model. Proximity from lineament zones will carry a suitability value. The same proximity classification from the water bodies suitability criteria was also assigned for Lineament Zones. Again, the combination of null slopes and shorter proximity to these features is expected to lower the probability of polluting water resources. The table below illustrates the rest of suitability values assigned for the other proximity classes: Agustin B. Graterole Page 16 8/19/2008
Slope The steepness of mountain slopes in Puerto Rico is a very important variable for identifying suitable areas for locating non-toxic solid waste landfills. As mentioned before, the island is characteristic of having a wide range of mountainous topography through out its territory. Slopes that are higher than 20 degrees were included in the Exclusion Areas 2008 map. However, the lesser angle of slope degrees, the less probability for flowage of pollutants and wastes. In the Site Suitability Model of this research, slopes that range from 0 to 5 are awarded the highest suitability value. The table below illustrates the rest of the values assigned to the other classes. Agustin B. Graterole Page 17 8/19/2008
Land Use/Cover Raster layers were reclassified to assign a value for the suitability of these types of land use and land cover. I assign the highest suitability value for Bushes and Shrubs land cover that doesn t even have agricultural value. The least suitability value was assigned for past agricultural lands that now are inactive. It is important to note that all forested areas, national parks, etc, were included on the Exclusion Areas Map 2008. Agustin B. Graterole Page 18 8/19/2008
Urban Areas Landfills are often known for emitting undesirable odors, specially affecting humans. Due to the nature of landfills, the creation of these odors is difficult to mitigate. This happens even more if the management of the landfill is not properly addressed for things such as the covering of wastes with dirt on a daily basis. People often protest for the construction of landfills in close proximity of populated areas. The urban areas layer used in this research gives a good idea of the location of populated areas in Puerto Rico for the year 2000. The higher the distance the landfill is from these areas, the higher the suitability. In the table below, values for suitability are assigned to urban areas proximity. Agustin B. Graterole Page 19 8/19/2008
The Site Suitability Model was finalized with the application of an overlay analysis (Figure 1). It consisted in using the Plus tool from raster Math tool applications for all the six previously mentioned raster layers (Water Table, Rivers and Streams, Lakes, Lineament Zones, Slope, Land Use/Cover and Urban Areas). Each individual raster layer contained values of 1, 3, 5, and 7. These values where summed between each individual raster layers. As a result, the areas that are represented with a higher total value will be the most suitable for the location of landfills. Layers: Resulting Layer Figure 1: Overlay Example Using Plus tool Agustin B. Graterole Page 20 8/19/2008
Results/Conclusions The values that resulted from the overlay analysis ranged from 11 to 49. These values were classified into the following four equal interval classes: 11 20.5, 20.5 30, 30 39.5, and 39.5 49. The class with the highest value defined the areas with the highest suitability. The class with the lowest value defined the areas with least suitability. (All resulting maps are shown on the following pages) The island of Puerto Rico is known for its scarce amount of terrain for properly locating nontoxic solid waste landfills. The Exclusion Areas 2008 and Site Suitability Model based maps of this project illustrates this fact. The created Exclusion Areas 2008 map covers about 75% of the total area of the island. Unsuitable places for the location of landfills because of high impact on environmental, human health and activities are pretty evenly spread through out the island. However, the highest valued suitable areas based from the Suitability Model analysis did discover some large enough terrains which could be explored. Most of these are located on the southern portion of the island. Further analysis for the viability of these places in terms of transportation and economics will be needed. *Due to the nature of the GIS compiled data utilized in this research, field studies are going to be necessary to corroborate results and address errors of geographic precision. Agustin B. Graterole Page 21 8/19/2008
Site Suitability Model for Landfills Map: Results of Site Suitability Model for the entire island w/o areas of exclusion. Agustin B. Graterole Page 22 8/19/2008
Map: Combination of Site Suitability Model and Exclusion Areas 2008 map as mask. Agustin B. Graterole Page 23 8/19/2008
Map: Combination of Site Suitability Model s places of highest value and Exclusion Areas 2008 map as mask. Agustin B. Graterole Page 24 8/19/2008
References Vive la Geografia de Puerto Rico (2003), Angel David Cruz Baez, Carlos Guilbe and Adolfo R. Lopez. Editorial Cordillera. Population Geography (2002), Gary L. Peters and Robert P. Larkin. Kendall/Hunt Publishing Company. Atlas de Puerto Rico (1997), Angel David Cruz Baez and Thomas D. Boswell. Published by the Cuban American National Council, Inc. Soils (2007), Randall J. Shaetzl and Sharon Anderson. Cambridge University Press. GIS Based Solutions for Waste Disposals, SM Ramasamy, C J Kumanan, K Palanivel of Centre for Remote Sensing, Bharathidasan University, Khajamalai Campus, Tiruchirappalli. GISdevelopment.net. Autoridad de Desperdicios Solidos, http://www.ads.gobierno.pr/portada.html. A New Approach to Landfill Site Selection in Ireland Using GIS Technology, Valerie Cummins, Vicki O Donnell, Alistair Allen, Joe Donnelly, Sotirios. Koukoulas, Coastal Resources Centre, Environment Research Institute, University College Cork, Ireland. Cork County Council, County Hall, Cork, Ireland. Agustin B. Graterole Page 25 8/19/2008