Soil Contamination Assessment and Remediation Planning for Former Crude Oil Spill Sites in Akwa Ibom State

This study conducts a professional soil contamination assessment and develops remediation plans for selected former crude oil spill sites in Akwa Ibom State, located in Nigeria's South South geopolitical zone. Akwa Ibom State has experienced extensive oil spill impacts on agricultural and mangrove soils, and formal regulatory compliance with the Hydrocarbon Pollution Remediation Project (HYPREP) and Department of Petroleum Resources standards requires systematic site characterisation followed by technically appropriate remediation planning. Using a tiered professional assessment approach, three former spill sites in Ibeno, Ikot Abasi, and Mbo local government areas were characterised by soil sampling at four Soil Sciencehs (0 to 15, 15 to 30, 30 to 60, and 60 to 100 cm) on a 20 by 20 metre grid. Analytical parameters included total petroleum hydrocarbons, polycyclic aromatic hydrocarbons by GC-MS, heavy metals, pH, organic carbon, and microbial hydrocarbon degrader counts. Risk assessment was conducted using the Environment Agency Contaminated Land Exposure Assessment model. Findings revealed that all three sites exceeded remediation trigger values for TPH and PAH at all sampled Soil Sciencehs, with the deepest contamination plume reaching 80 cm at the Ibeno site. Human health risk was significant through soil ingestion and vegetable crop pathways. Site-specific remediation plans were developed combining biostimulation, bioventing, and landfarming as the recommended technology sequence. Cost estimates and monitoring frameworks are provided for each site. The study contributes a replicable professional contamination assessment and remediation planning methodology for Niger Delta spill legacy sites. Keywords: crude oil contamination, remediation planning, Akwa Ibom State, TPH, bioremediation.