Authors : Udechukwu John A.; Udeme Hanson Iron; Ndifreke Edem Udoh

Volume/Issue : Volume 11 - 2026, Issue 5 - May

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DOI : https://doi.org/10.38124/ijisrt/26May2106

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Abstract : This study investigated the effect of sewage effluent on the geotechnical characteristics of adjacent soil, using St. Luke’s Hospital, Anua, Uyo, Akwa Ibom State, Nigeria, as a case study. A comparative experimental approach was adopted in which effluent-affected soil samples collected at 1 m from a functional soakaway pit were analyzed against control samples obtained 50 m away. Laboratory investigations included particle size distribution, Atterberg limits, natural and air-dried moisture content, specific gravity, Standard Proctor compaction test, and California Bearing Ratio (CBR) test. Results revealed a 42.05% relative increase in fine particles in the effluent-affected soil, indicating possible particle migration and biological clogging. The liquid limit and plastic limit decreased by 12.12% and 13.15%, respectively, while the plasticity index reduced by 1.2%, suggesting alteration in soil consistency due to effluent interaction. Compaction characteristics showed a 1.61% increase in maximum dry density and an 8.33% decrease in optimum moisture content in the effluent soil. However, despite improved compaction density, the unsoaked CBR value decreased by 3.4%, indicating reduced loadbearing capacity. Specific gravity also reduced by 0.75%, suggesting the presence of organic infiltration. The findings demonstrated that prolonged sewage effluent exposure modified soil gradation and consistency characteristics and, more critically, reduced subgrade strength. The study concluded that soils surrounding sewage disposal systems may experience structural weakening despite apparent improvements in compaction parameters. It is therefore recommended that engineering construction near effluent discharge zones incorporate soil replacement, stabilization, or improved wastewater management practices to mitigate potential foundation and pavement failures.

Keywords : Sewage Effluent, Soil Contamination, Compaction Characteristics, California Bearing Ratio, Geotechnical Properties, Subgrade Strength.

References :

1. World Health Organization. (2017). Guidelines on sanitation and health. Geneva, Switzerland: WHO.
2. United Nations Environment Programme. (2016). A snapshot of the world’s water quality: Towards a global assessment. Nairobi, Kenya: UNEP
3. United States Environmental Protection Agency. (2002). Onsite wastewater treatment systems manual. Washington, DC: U.S. EPA.
4. Chittaranjan, M., et al. (2021). Influence of alum sludge on the engineering properties of expansive soil. International Journal of Geotechnical Engineering, 15(4), 455–462
5. Kavya, R., & Arya, U. S. (2022). Effect of sewage sludge on compaction and strength characteristics of clayey soil. Journal of Materials in Civil Engineering, 34(2), 04021456.
6. ASTM International. (2017a). ASTM D2216–17: Standard test methods for laboratory determination of water (moisture) content of soil and rock by mass. West Conshohocken, PA: ASTM International
7. British Standards Institution. (1990). BS 1377: Methods of test for soils for civil engineering purposes. London, UK: BSI
8. ASTM International. (2017c). ASTM D6913–17: Standard test methods for particle-size distribution (gradation) of soils using sieve analysis. West Conshohocken, PA: ASTM  International.
9. ASTM International. (2017b). ASTM D4318–17: Standard test methods for liquid limit, plastic limit, and plasticity index of soils. West Conshohocken, PA: ASTM International.
10. ASTM International. (2017d). ASTM D698–12(17): Standard test methods for laboratory compaction characteristics of soil using standard effort. West Conshohocken, PA: ASTM International.
11. ASTM International. (2017f). ASTM D1883–16: Standard test method for California bearing ratio (CBR) of laboratory-compacted soils. West Conshohocken, PA: ASTM International.
12. Das, B. M. (2010). Principles of geotechnical engineering (7th ed.). Stamford, CT: Cengage Learning.
13. Mandlekar, S., et al. (2020). Effect of sewage sludge on compaction characteristics of soil. International Research Journal of Engineering and Technology, 7(6), 2345–2350.
14. Terzaghi, K., Peck, R. B., & Mesri, G. (1996). Soil mechanics in engineering practice (3rd ed.). New York, NY: John Wiley & Sons.