PRE-FOUNDATION COMPETENCY AND CORROSSIVITY STUDY: A CASE STUDY OF CANAL VIEW ESTATE, ISOLO, LAGOS

Constant separation traversing and Vertical Electrical Sounding (VES) techniques have been used in Canal View Estate, Isolo, Lagos, Southwest Nigeria to determine subsurface competency and corrosivity evaluation for structural development and other civil engineering applications such as underground pipeline for sewage and petroleum product transportation in the area. Twelve vertical electrical soundings (VES) and five 2D Wenner data were acquired from five different traverses established in the study area. Models obtained from 1D inversion of each traverse were used for construction of geo-electric sections which exhibit the main geo-electric characteristics of the geological units present in the area. Data obtained for each of the traverses in the 2D Wenner array were used to present Inverse Model Resistivity Sections. The interpreted results showed that the geoelectric sections consist of four to five geoelectric layers namely: the topsoil, clayey sand, clay, sandy clay and sand. The investigation revealed the fourth and fifth layers, interpreted as Sand, to be most competent and essentially non corrosive unit for shallow foundation for small to medium engineering structures and buried pipelines. These layers have thickness values that range between 9.8m to 44.0m and resistivity values of about 234.8Ωm to 6844.5Ωm.