### 1. Introduction

### 2. Materials and Methods

### 2.1. Study Area and Landfill Area Estimation

^{2}and their population number is about 7.36 million.

##### (1)

$${\mathit{\Phi}}_{p}\hspace{0.17em}(B)\hspace{0.17em}{W}_{t}={\theta}_{q}\hspace{0.17em}(B)\hspace{0.17em}{e}_{t}$$*Φ*

*(*

_{p}*B*) is an autoregressive operator of order

*p*,

*θ*

*(*

_{q}*B*) is a moving average operator of order

*q*and

*W*

*= Δ*

_{t}

^{d}*X*

*[39, 40] is a successive difference at*

_{t}*d*

*difference of*

^{th}*X*

*and is expressed as follows:*

_{t}### 2.2. Ranking of Landfill Site Criteria

If the sample size, n, is odd, then the median is selected by ${\left(\frac{n+1}{2}\right)}^{th}$. This observation can be denoted as ${X}_{\left(\frac{n+1}{2}:n\right)}$, and the general formula is

If the sample size, n, is even, then the median is selected by ${\left(\frac{n}{2}\right)}^{th}$. This observation can be denoted as ${X}_{\left(\frac{n}{2}:n\right)}$, and the general formula is

##### (4)

$$\left\{{X}_{\left(\frac{n}{2}:n\right)1},{X}_{\left(\frac{n}{2}:n\right)2},\cdots ,{X}_{\left(\frac{n}{2}:n\right)n}\right\}$$

### 3. Results and Discussion

### 3.1 Landfill Area Estimation

##### (7)

$${y}_{t}=0.219-0.455{y}_{t-1}-0.482{y}_{t-2}-0.41{y}_{t-3}-0.571{y}_{t-4}-0.773{y}_{t-5}-0.412{y}_{t-6}+{\varepsilon}_{t}-{\varepsilon}_{t-1}$$^{3}. According to Vision 2020, the planned solid waste disposal scenarios are recycling (22%), composting (8%), incineration (16.3%), inert landfill (9.1%), and sanitary landfill (44.1%) of the total solid waste generated. Consequently, the total required landfill area was calculated using the following assumptions:

The average waste disposal height equals 22 m

The total area required for administration, utilities, and roads equals 40% of the waste disposal area. Therefore, the total landfill area may be calculated using Eq. (8).

### 3.2. Ranking of Landfill Site Criteria

### 3.3. Landfill Siting

^{2}, respectively. However, there is an urgent need to develop a scientific approach for determining a landfill site location in Selangor, due to increasing amounts of solid waste and land scarcity. Therefore, a restrictions map to exclude unsuitable areas that cannot be used for the disposal site because of limiting factors, was built. These factors were based on Malaysian guidelines for development of solid waste sanitary landfill [49]. Fig. 3 shows the landfill restriction areas in Selangor state. All restriction areas were determined using a Boolean operation [50]. It represents around 82% of the total Selangor area.