landfill site suitability analysis for non-toxic solid...

Agustin B. Graterole 8/19/2008

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


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


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.


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.


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.


Feet

-47.5065

4,361


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


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 Public Areas

Lineament zones Leisure/Recreational Areas

Main Aquifers Cultivated Agricultural Land

Rivers and Streams Mining Areas

Medium Density Forests Principal Roads


Map: 2008 Exclusion Areas Map


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


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.


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.


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:


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:


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.


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.


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.


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.

Figure 1: Overlay Example Using “Plus” tool

Layers:

Resulting Layer


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 non-

toxic 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.


Map: Results of Site Suitability Model for the entire island w/o areas of exclusion.

Site Suitability Model for Landfills


Map: Combination of Site Suitability Model and Exclusion Areas 2008 map as mask.


Map: Combination of Site Suitability Model’s places of highest value and Exclusion Areas 2008 map as mask.


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.

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