Undergraduate project

EFFECT OF OIL CONTAMINATION ON SOIL BEARING CAPACITY IN FOUNDATION DESIGN

civic engineering · · PROPOSAL

Abstract

1. INTRODUCTION Soil is a fundamental material in civil engineering as it forms the foundation upon which all structures are constructed. The performance, safety, and durability of any structure largely depend on the ability of the soil to support loads without undergoing excessive deformation or failure. This property is known as the bearing capacity of soil, and it is influenced by several factors such as soil type, density, moisture content, and shear strength characteristics.

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A PROJECT PROPOSAL ON EFFECT OF OIL CONTAMINATION ON SOIL BEARING CAPACITY IN FOUNDATION DESIGN PRESENTED BY SUBMITTED TO THE DEPARTMENT OF CIVIL ENGINEERING TECHNOLOGY, , APRIL 2026 . TABLE OF CONTENT FRONT PAGE CERTIFICATION TABLE OF CONTENT 1.0BACKGROUND OF THE STUDY 2.0PROBLEM STATEMENT 3.0AIM AND OBJECTIVES 4.0SIGNIFICANCE OF THE STUDY 5.0SCOPE OF THE STUDY 6.0LITERATURE REVIEW 7.0METHODOLOGY 8.0 EXPECTED RESULTS 9.0 ANTICIPATED CONCLUSION 10TIMELINE 11. BUDGET INTRODUCTION Soil is a fundamental material in civil engineering as it forms the foundation upon which all structures are constructed. The performance, safety, and durability of any structure largely depend on the ability of the soil to support loads without undergoing excessive deformation or failure. This property is known as the bearing capacity of soil, and it is influenced by several factors such as soil type, density, moisture content, and shear strength characteristics. 1.1 Background of the Study Soil is a fundamental component in civil engineering works, particularly in foundation design, where its ability to safely support structural loads is measured by its bearing capacity. In ideal conditions, soils possess sufficient shear strength, compaction, and stability to carry building loads without excessive settlement or failure. However, in many parts of Nigeria, especially in oil-producing regions such as the Niger Delta, soil conditions have been significantly altered due to crude oil exploration, transportation, and frequent oil spillages. Oil contamination introduces hydrocarbons into the soil matrix, which changes the natural arrangement of soil particles and affects their engineering behaviour. When crude oil infiltrates the soil, it coats the particles, reduces inter-particle friction, and interferes with normal compaction processes. This results in weaker soil structure, reduced density, and lower shear strength, all of which directly contribute to a reduction in soil bearing capacity (Oni&Fagbenle, 2020). Over time, such changes make the soil less reliable for supporting structural foundations. Several studies carried out in Nigeria and other regions have confirmed these effects. For instance, Adetoro and Akinyemi (2022) observed that crude oil contamination significantly reduces the compaction characteristics of lateritic soils, leading to lower dry density and higher void ratios. This means that the soil becomes looser and more compressible, which is not suitable for foundation support. Similarly, Owolabi and Adegoke (2022) reported that contaminated soils show a drastic reduction in California Bearing Ratio (CBR), which is a key parameter used in evaluating soil strength for construction purposes. In the Nigerian context, the problem is even more severe due to continuous oil exploration activities. Uguru et al. (2025) reported that soils in Rivers and Delta States exhibit severe degradation in engineering properties as a result of long-term exposure to crude oil contamination. These changes are not just surface-level; they affect deeper soil layers, making even subsoil conditions unreliable for foundation design. This is particularly concerning because many communities in these regions continue to expand residential and infrastructural development without adequate geotechnical investigation. Furthermore, Ibrahim and Sule (2023) emphasized that oil-contaminated soils often fail under standard allowable bearing pressures used in foundation design. This failure can lead to differential settlement, cracking of structures, and in severe cases, complete structural collapse. This highlights the importance of proper soil testing before construction activities are carried out in contaminated areas. Beyond physical changes, hydrocarbon contamination also affects the chemical and biological properties of soil. According to Onwujekwe et al. (2023), oil contamination disrupts soil microbial activity, which plays an important role in maintaining soil structure and stability. When these natural processes are disturbed, soil becomes even more vulnerable to degradation over time. In addition, Nwachukwu and Bartholomew (2023) developed predictive models showing that as the level of hydrocarbon contamination increases, there is a corresponding and measurable decrease in soil bearing capacity. This relationship clearly demonstrates that contamination level is directly linked to foundation performance risk. In urban areas such as Lagos, Okebalama et al. (2024) also observed that indiscriminate disposal of spent engine oil into the soil significantly reduces soil strength and introduces heavy metal contamination, further worsening soil conditions. This shows that oil-related soil contamination is not limited to oil exploration areas alone but is also present in urban environments. Due to these challenges, several remediation techniques have been explored to improve the engineering properties of contaminated soils. Olumide (2025) found that cement and lime stabilization can significantly improve the bearing capacity of petroleum-contaminated soils, making them more suitable for construction purposes. Similarly, bioremediation techniques have been shown to reduce hydrocarbon concentration and gradually restore soil strength (Onwujekwe et al., 2023). In summary, oil contamination poses a serious threat to soil stability and foundation performance in Nigeria. The continuous degradation of soil properties due to hydrocarbon exposure makes it necessary to properly assess soil conditions before any construction activity is carried out. Without proper treatment or stabilization, building on contaminated soil increases the risk of structural failure, making this study highly relevant in the field of foundation engineering. PROBLEM STATEMENT Soil bearing capacity plays a very important role in foundation design because it determines the ability of the soil to support the load of a structure. For any building to remain stable and safe, the soil must have enough strength to carry the applied loads without excessive settlement or failure. However, in many areas, soil becomes contaminated with oil due to spills, leakage from storage tanks, and improper disposal of petroleum products. This contamination can change the natural properties of the soil, reducing its strength and affecting its ability to support structures properly. Despite this issue, oil contamination is often not properly considered during site investigation and foundation design. This can result in weak foundations, structural damage, and increased maintenance costs. Therefore, there is a need to study the effect of oil contamination on soil bearing capacity in order to provide better understanding and ensure safer and more reliable foundation design. In many oil-producing communities in Nigeria, particularly within the Niger Delta region, crude oil contamination of soil has become a persistent environmental and engineering challenge. Despite the obvious presence of hydrocarbon pollution from pipeline leakages, oil spills, and improper disposal of petroleum products, construction activities are still frequently carried out on affected lands without adequate geotechnical investigation. The major problem is that oil contamination significantly alters the natural engineering properties of soil, especially its shear strength, compaction characteristics, and overall bearing capacity. When these properties are weakened, the soil becomes incapable of safely supporting structural loads, leading to foundation instability, excessive settlement, cracking of buildings, and in severe cases, total structural failure (Ibrahim &Sule, 2023). What makes this issue more critical is that in many developing communities, construction decisions are often made without proper soil testing due to cost, lack of awareness, or poor regulatory enforcement. As a result, buildings are sometimes constructed on soils that have already lost their structural integrity due to hydrocarbon contamination (Uguru et al., 2025). Therefore, the problem this study addresses is the continuous use of oil-contaminated soils for foundation construction without adequate understanding of how such contamination affects soil bearing capacity and overall structural safety. 3.0 AIM AND OBJECTIVES Aim: The aim of this study is to critically examine the effect of oil contamination on soil bearing capacity and to evaluate its implications for safe and sustainable foundation design in Nigeria. The specific

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objectives of this study are to: • Investigate how oil contamination alters the physical and mechanical properties of soil • Assess the implications of reduced soil strength on foundation design and structural stability • Review existing methods used for improving or stabilizing oil-contaminated soils • Provide recommendations for safe construction practices in contaminated soil environments 4.0 SIGNIFICANCE OF THE STUDY This study will help to show how oil contamination affects the strength of soil and its ability to carry building loads. It will be useful to engineers and builders by helping them understand the risks of constructing on contaminated soil. It will also help in making better decisions during site investigation and foundation design, especially in areas where oil spills are common. This can reduce problems like foundation failure, cracks, and settlement in buildings. In addition, the study will be helpful to students and future researchers as it provides useful information and can serve as a reference for similar projects. 5.0 SCOPE OF THE STUDY This study is focused on examining the effect of oil contamination already present in the soil on its bearing capacity. Soil samples will be collected from a contaminated area and also from a clean area for proper comparison. The samples will be tested in the laboratory to determine their strength and how well they can support loads. The results from both samples will be compared to see the effect of the contamination. The study is limited to the samples collected and the tests carried out in the laboratory. It does not cover all soil types or different environmental conditions, so the results are based on the area selected for this study. . The research will evaluate important geotechnical properties such as: •Atterberg limits •Compaction characteristics •Shear strength parameters •Bearing capacity The study will be limited to one or two soil types commonly found in Nigeria, such as sandy or clayey soil. However, the study will not cover field testing, long-term environmental impacts, or advanced soil remediation techniques. 6.0 LITERATURE REVIEW Oil contamination of soil has become one of the most serious environmental and geotechnical problems in Nigeria, particularly in oil-producing areas such as the Niger Delta. Over the years, continuous oil exploration, pipeline leakage, and accidental spills have introduced large quantities of hydrocarbons into the soil system, leading to significant changes in its engineering behaviour. These changes are critical in civil engineering because soil serves as the primary foundation material for all structural works, and any reduction in its strength directly affects building safety and stability. Studies have shown that when crude oil enters the soil, it alters the natural arrangement of soil particles by coating them with a thin layer of hydrocarbon. This reduces inter-particle friction and weakens the bonds that hold the soil structure together. As a result, the soil becomes loose, less compact, and more compressible, which significantly reduces its ability to support structural loads (Oni&Fagbenle, 2020). This phenomenon is particularly dangerous in foundation design because it directly affects the bearing capacity of the soil. In addition, research carried out on lateritic soils in Nigeria has shown that oil contamination affects compaction characteristics. Adetoro and Akinyemi (2022) observed that contaminated soils have lower dry density and higher void ratios compared to uncontaminated soils. This means that the soil becomes weaker and more porous, making it unsuitable for supporting heavy structures. Similarly, Owolabi and Adegoke (2022) reported that oil contamination causes a significant reduction in California Bearing Ratio (CBR), which is a key parameter used in determining soil suitability for pavement and foundation works. The geotechnical implications of these changes are very serious. When soil loses its strength due to contamination, its shear resistance decreases, leading to a reduction in safe bearing capacity. Elsaigh and Oluremi (2021) explained that contaminated soils tend to behave more plastically and are more prone to deformation under load. This makes them unreliable for supporting structures without prior treatment or stabilization. In the Nigerian context, the problem is even more pronounced due to the scale of oil exploration activities and environmental pollution. Uguru et al. (2025) reported that soils in Rivers and Delta States show severe degradation in engineering properties due to long-term exposure to crude oil. These soils often fail to meet basic geotechnical requirements for foundation design, making construction in such areas highly risky without proper investigation and remediation. Furthermore, Ibrahim and Sule (2023) emphasized that many foundation failures in Nigeria are linked to the use of inadequate or contaminated soils without proper site investigation. They noted that when foundations are built on weak soils, the structures are likely to experience settlement, cracking, and in extreme cases, collapse. This highlights the importance of understanding soil conditions before construction begins. Beyond physical and mechanical effects, oil contamination also affects the biological and chemical composition of soil. Onwujekwe et al. (2023) explained that hydrocarbons disrupt microbial activity in the soil, which plays an important role in maintaining soil structure and natural stability. When these biological processes are affected, soil degradation becomes more severe and long-lasting. In urban areas such as Lagos, oil contamination is also observed in mechanic workshops and industrial zones where waste engine oil is indiscriminately disposed of on the ground. Okebalama et al. (2024) found that such practices significantly reduce soil strength and introduce additional environmental hazards such as heavy metal contamination, further worsening soil quality. Recent studies have also shown that there is a direct relationship between the level of oil contamination and reduction in soil bearing capacity. Nwachukwu and Bartholomew (2023) demonstrated through predictive modeling that as hydrocarbon concentration increases, soil strength decreases proportionally. This confirms that contamination level is a key factor in determining foundation safety. Due to these challenges, researchers have explored various methods of improving contaminated soils. Olumide (2025) found that cement and lime stabilization can significantly improve the bearing capacity of oil-contaminated soils, making them suitable for construction purposes. In the same way, bioremediation techniques such as biostimulation have been shown to reduce hydrocarbon concentration and gradually restore soil strength (Onwujekwe et al., 2023). In summary, the literature clearly shows that oil contamination has a severe negative impact on soil bearing capacity and overall geotechnical performance. This makes it unsafe to use such soils for foundation construction without proper testing and treatment. Therefore, understanding the behaviour of oil-contaminated soils is essential for safe, durable, and sustainable foundation design in Nigeria. 7.0 METHODOLOGY 7.1 Materials The materials for this study include soil samples, crude oil, water, and the necessary laboratory equipment. The soil samples will be collected from a selected location and used as the main material for the experiment. They will first be tested in their natural condition before contamination. Crude oil will be added in measured amounts to the soil to simulate contamination and observe its effect on soil properties. Water will be used during sample preparation and in tests that require moisture control. The laboratory equipment to be used includes the oven for moisture content determination, weighing balance for accurate measurement of samples, sieve set for particle size analysis, Atterberg limits apparatus for consistency tests, compaction mould and rammer for compaction tests, and CBR testing machine or shear box apparatus for determining soil strength and bearing capacity.

EFFECT OF OIL CONTAMINATION ON SOIL BEARING CAPACITY IN FOUNDATION DESIGN

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