Suitable Area for Landfill Development: Identification And

SUITABLE AREA FOR LANDFILL DEVELOPMENT: IDENTIFICATION AND CALIBRATION USING A GIS APPROACH

Dr. Sharifah Norkhadijah Syed Ismail
Umi Raihana Abdul Rahman

Universiti Putra Malaysia (UPM)

ABSTRACT

Selangor is one of the developed states in Malaysia, with a diversified economy including agriculture, industry, commerce, and tourism. The volume of waste in Selangor is projected to increase from 2.9 million tonnes in 2010 to 3.6 million tonnes in 2020. The existing eight landfills in Selangor could only receive half of this waste per year (1.6 million tonnes per year), highlighting the need for new landfills to be built.

Searching for a new location to be developed as a waste landfill is a complicated process. It involves many factors such as environmental, socio-cultural, technical, and economic considerations. Planners usually face great difficulties in establishing the most suitable locations for landfilling due to shortages of space and increasing quantities of solid waste, driven by rapid urbanization. Additionally, studies have proven that the proximity of housing areas to waste landfills can lead to a reduction in house prices. This is due to the uncertainty relating to health effects, which has become an inescapable problem affecting decisions on purchasing houses near waste landfills.

The assessment performed in Ismail (2011) identified 7% of the state area as the most suitable for landfill development. In that study, twelve candidate sites with a size of more than 150 hectares, mainly located on agricultural land, were deemed the most suitable. The assessment suggested several suitable areas for future waste landfills in the site suitability index maps, but the accuracy of this map was not measured. Due to limited data, validation of the map could not be performed, and the relationship between house prices and the distance to waste landfills was not studied. Therefore, the aim of this study was to validate the suitability index map and determine the relationship between house prices and waste landfill characteristics.

Secondary data on river water quality from 2008 to 2011 was obtained from the Department of Environment, while single and double-storey terraced house data were obtained from the Valuation and Property Services Department (NAPIC), Ministry of Finance Malaysia. All data were screened and evaluated for outliers before being further analyzed. SPSS was used for descriptive statistics, followed by comparison and regression analysis. GIS was applied to interpolate the river water quality data and to validate the site suitability index map.

The results of this study highlight that all the water quality parameters tested were within the national drinking water quality standard. However, E-coli and total coliform showed high concentrations, with mean ± SD values of 66,513 ± 101,286 count/100 ml and 3,954,458 ± 2,356,370 count/100 ml, respectively. The GIS overlay output showed that the majority of candidate sites were located in areas with high concentrations of water quality parameters such as BOD, COD, NHNL, PO, and E-coli. The analysis results indicated that BOD (r = -0.571), COD (r = -0.589), NHNL (r = -0.632), and PO (r = -0.592) had a moderate correlation with the site suitability index map.

The overall findings of this study indicate that six candidate sites from the validated map were suitable for landfill development. The sites were C4, C7, C8, C10, C11, and C12. Based on the water quality data, these areas have minimal risk of further contaminating the land and polluting river water. Seven variables significantly influenced the terraced house prices in the regression analysis. These variables were built-up area, district, lot size, years, ownership, number of bedrooms, and distance to the landfill. However, the status of the landfill (i.e., closed or open) and landfill type did not influence terraced house prices.

The findings of this study can serve as a guideline for map calibration and assist respective government agencies in township planning. The outcome of this study also predicts the possible effects of waste landfilling on real estate prices in the country. However, the results of site characteristics on house prices were generalized for terraced houses only. Therefore, further assessment is needed in future research.