Finding a suitable site for sanitary landfilling has become a challenge amidst the shortage of sanitary landfills (SLF) for solid waste disposal. The different site selection parameters specified under the law must be considered in determining the suitability of an SLF site. For this study, a total of 10 parameters were used which were based on the existing guidelines for SLF siting. In this study, the identification and mapping of suitable SLF areas in Batangas Province were done through the integration of the Geographic Information System (GIS) and the Analytic Hierarchy Process (AHP). This study mapped an area of 884.42 ha. as highly suitable for sanitary landfilling, 62,486.15 ha. as moderately suitable, and 248.89 ha. as marginally suitable, with the remaining areas of the province considered unsuitable. The municipality of San Juan has the most suitable areas while the municipalities of Balete, Mataasnakahoy, and San Nicolas have no suitable areas. Ultimately, the results of this study can be used to support future solid waste management policies and decisions of the different stakeholders in a manner that considers the negative impacts of SLFs on humans and the environment and reflects compliance with the provisions of the law.
Keywords: Sanitary Landfill; GIS; AHP; Suitability Analysis; Philippines
1. Introduction
Solid waste, over the past years, has persisted to be one of the most evident and silently dangerous environmental problems in the country. These solid wastes are deposited in the oldest forms of waste management: open and controlled dumpsites located in various parts of the country (Ghobadi et al., 2013). The aggressive pursuit for economic growth along with an increase in population and improvement of living standards has resulted in the manufacture, distribution, and use of products; leading to the generation of wastes that contribute heavily to environmental degradation and global climate change. The issue of solid waste management is a key concern for the environment and public health alike.
The increasing complications to the environment and public health brought by existing dumpsites pushed the movement for the construction and use of sanitary landfills (SLF) as primary waste management facilities in the country. An SLF is a land disposal site that employs the principle of spreading solid wastes in thin layers, compacting the material to the smallest possible volume, and applying cover material after each operating day (Terlecky, 1980). An “engineered” method of waste disposal means that garbage is handled at a disposal facility that is designed, constructed, and operated in a manner protective of public health and the environment. However, of the estimated 1,700 SLF needed to address the issue of ecological solid waste management, roughly 108 SLFs have been operating (Mayuga, 2020).
The Republic Act No. 9003 (RA 9003) otherwise known as the “Ecological Solid Waste Management Act of 2000” was passed into law in 2001 in response to the challenge of addressing the worsening issue of solid waste management in the Philippines (Official Gazette of the Republic of the Philippines, 2001). RA 9003 laid down solid waste management as a discipline associated with the control of generation, storage, collection, transfer and transport, processing, and disposal of solid wastes (Aquino et al., 2021). The law also established the National Solid Waste Management Commission (NSWMC) and the Solid Waste Management Board (SWMB) in each Local Government Unit (LGU) which is represented by multiple stakeholders including public officials and the private sector. The law called for the development and operation of SLFs as a final disposal site for solid wastes and, eventually, residual wastes of a municipality or city, or a cluster of municipalities and/or cities.
The Province of Batangas in the Southern Tagalog region is an emerging province located south of Metro Manila for industrial activities and population growth. Comprised of 34 cities and municipalities, the vast land area of the province which approximately stands at 3,165.81 km2, is ranked as the 44th biggest province in the Philippines (Miguel, 2016). In 2015, it recorded a population of 2,694,335 people and is considered the 7th largest in the country out of 81 provinces (Philippine Statistics Authority, 2016). With a population growth rate of 2.41% recorded for the years 2010 to 2015, the province is not only expected to be more populous in the coming years, but waste generation and management will also be a key aspect of this growth.
Batangas province produces an estimated 860.81 tons/day of waste of which 46.64% are biodegradable, 25.28% are recyclable, 24.75% are residual, and 3.33% are special wastes (Environmental Management Bureau CALABARZON, 2019). A waste generation increase of up to 969.66 tons/day is projected for the year 2023. The province has the 2nd smallest waste generation per capita in the CALABARZON region with 0.291 kg/capita. A total of seven (7) SLFs operate within the province in 2020, of which three (3) are privately owned while the rest are government owned. These SLFs cater to the waste disposal needs of the various cities and municipalities within the province (Environmental Management Bureau CALABARZON, 2019). However, the number of operating SLFs only accounts for around 20.59% of the present LGUs within the province which stands at thirty-four (34) and could decrease in the coming years as the lifespan of the operating SLFs come to an end.
Several studies have been published internationally that combine Geographic Information System (GIS) with multiple criteria decision-making analysis like Analytic Hierarchy Process (AHP) to aid in the screening and selection of sites for development as SLFs (Akbari et al., 2008; Şener et al., 2010; Vasiljević et al., 2012; Ghobadi et al., 2013; Torabi-Kaveh et al., 2016). The success in the use of GIS-based methods combined with multi-criteria decision-making analysis methods such as AHP provides an opportunity for its application in the Philippine setup. Relevant laws and policies relating to site selection and the establishment of sanitary landfills in the Philippines are already in place and are supported by various government agencies (Environmental Management Bureau, 2015; National Solid Waste Management Commission, 2016).
This study builds on the applicability of GIS and AHP based on the previous studies by aiming to identify and map the suitability of areas within the Batangas Province for sanitary landfilling using an integration of GIS and AHP. It also includes 1) identifying the weight of the selected site selection parameters listed in the National Solid Waste Management Commission Resolution No. 64, Series of 2013 (NSWMC 64-2013) for sanitary landfill site suitability analysis; 2) quantifying the land areas that are suitable for sanitary landfilling; and 3) evaluating the possibility of having an SLF in each city or municipality of Batangas Province based on the availability of suitable SLF sites.
The area of the study is limited only to the cities and municipalities within the mainland area of Batangas Province. All islands of the province except Taal Volcano Island are not included in this study.