## 2. Scope  
The Khurmala oil and gas field is spread from 30 km southwest of Erbil City, and is 22 km long and 3 km wide. The crude oil produced in the field wells that are spread across the Khurmala dome was collected at stations (1--North: collection from a network of 29 oil wells; 2--South: collection from a network of 26 oil wells; and 3--Middle: collection from a network of 20 oil wells) through various 150 mm flow lines and then sent to the Central Process Station (CPS-1 and CPS-2) through 500 mm trunk pipelines. After processing, the crude oil was pumped for export.  
The historical activities of the Khurmala dome began in 1935 with the drilling of the first well. In 1935-1977, 12 wells were drilled. Development then began in 1988 and the first oil production occurred in 2009.  
Crude oil is among the leading causes of terrestrial pollution due to its superior ability to spread, interact, and penetrate the soil in many forms and various means through its dependence on biological, physical, and air variables. There are several different sources of hazards in crude oil contaminated soil in the Khurmala oil field, including exploration and application processes. Therefore, a goal was set to minimize the amount of pollution in the field and remediate the contaminated soil by constructing specific concrete containers for collecting waste crude oil and mixing the contaminated soil with an appropriate cement type, respectively.  
The above activities create significant soil pollution due to inappropriate disposal, oil spills, tank leakage, and pipeline breakage [29]. In the Khurmala oil field, the main sources of soil pollution are as follows:  
1. Burning pit: This is a pit that is prepared to collect the crude oil that is tested and drained during oil well testing through a special pipe called the burning pipe. A check is necessary to determine the quantity and quality of crude oil, utilizing a test point and a flow meter attached to the burning pipe, as shown in Figure 1a.
2. Random pit: If the pipeline is not accessible for a particular location, the alternative is unloading. The oil in the tankers must be tested. The tested oil then has to be randomly handled. The tested oil is dealt with by disposal in a designated pit called the random pit, as shown in Figure 1b, from which oil can leak into the soil from the older pits. Therefore, these old pits must be remedied. Fortunately, in the Khurmala oil field, a particular separator system is currently used. An oil-water separator system is designed to isolate total quantities of oil and suspended solids from the oil refinery wastewater effluents. This system is based on preventing any leakage into the surrounding and underground soil under Health Safety and Environmental regulations (HSE), as shown in Figure 1c.
3. The absence of a closed drain system in the facilities (including pumps, equipment, pipes, and valves) frequently causes various oil leakage accidents, which can cause severe pollution to the surrounding soil, as shown in Figure 1d. These problems can be controlled through the use of close drain systems linked to a piping system connected to a particular basin for this leakage. Unfortunately, this system is not currently in use at the Khurmala oil station.  
4. Flow lines under or above the ground that transport crude oil from the well to stations are subjected to corrosion due to H2S if a corrosion inhibitor is not used, leading to holes in these pipes, causing oil leakage and then soil contamination.