Assessment of Geotechnical Properties of Soil in Capitol Gully Erosion Site, University of Benin, Benin City, Edo state

Abstract

A geotechnical assessment of soils in Capitol gully erosion site in University of Benin was carried out in order to evaluate the susceptibility of the soil to erosion. Soil samples were collected with a hand auger from nine(9) sampling points in the study area at a depth of 1m. The geotechnical properties of the soil samples analyzed in the laboratory were Sieve analysis, Atterberg Limits, Compaction, Moisture content and Shear strength. This work was carried out to evaluate the effect of dumping of metal scraps, used batteries, packaging materials, spent lubricants and worn-out parts, which contain contaminates, such as heavy metals which is highly toxic and hazardous to soil, fauna, and man. Uwelu auto-shops and mechanic workshops lies within the Drift/Top soil in the Benin Formation. Nine (9) samples points including control were profiled at 0-5 cm, 5-10 cm, 10-15cm and 15-30cm. Using auger from nine different point at the automobile mechanic workshop in order to get a representative sample (composite sample). The physiochemical analysis of the soil was carried out using standard method (pH, EC, TDS) and heavy metals(Ni, Cr, V, Pb, Cd, Zn). At profile depth 5-10 cm and 10-15 cm, there was significant difference between control and Cr, V, Pb, Cd, Zn and EC. Cd, V, Pb, Zn and Cr and the Contamination Factor value was greater than 1.5 in all the profile samples which translates to Contamination from anthropogenic sources. Plastic Limit Index (PLI) of the profiles revealed that the sub soil at 10-15 cm and 15-30 cm where the most contaminated with the highest PLI values. Futhermore, it was observed that the soil sample comprised mainly of sands and more fines with low and high plasticity. Monitoring and further studies on the level of these heavy metals should be carried out in the near future and at intervals to ascertain long-term effects of this anthropogenic impact.