Impact of Sewage Water Contamination on the Unconfined Compressive Strength of Soil Samples from Wilberforce Island, Nigeria

Abstract

This study investigates the impact of sewage water contamination on the unconfined compressive strength of soil samples collected from Wilberforce Island, Bayelsa State, Nigeria. Soil samples were subjected to varying concentrations of sewage water (0% to 8%) and cured for periods ranging from 7 to 28 days. The sewage water, characterized by a slightly acidic pH of 6.7, significant organic matter, nitrogen, and heavy metals, was sourced from a soak-away pit at the Faculty of Engineering block, Niger Delta University. The results indicate a general increase in optimum moisture content and liquid limits with higher contamination levels, while plastic limits and maximum dry densities showed variable trends. The strength of contaminated soils exhibited fluctuations during the curing period, with the control samples maintaining the highest unconfined compressive strength after 28 days. These findings provide insights into the degradation of soil strength due to sewage water contamination and underscore the necessity for effective waste management practices to mitigate soil pollution and its impact on the design and construction of civil engineering structures.

Keywords — Sewage water contamination, Unconfined compressive strength, Soil properties, Curing

period, Waste management practices