Abstract: Soil corrosion is a serious threat to the integrity of buried structures such as underground storage tank and many other structures. So evaluation of subsurface soil corrosivity using electrical resistivity methods was carried out, with focuses on the assessment of corrosivity probability of the subsurface layers. A shallow geophysical investigation for the corrosivity of subsurface soil at a proposed filling station site in Akure using 2D electrical resistivity imaging profiling was conducted to produce an approximate model of the subsurface resistivity. A total of three horizontal profilings involving the Wenner array 2D imaging was established in the East-West directions of the site investigated and was used to generate 2D pseudosections for the study area. The pseudosection results revealed the corrosivity status of the subsurface soil in the area based on their resistivity values. To further study the corrosive nature of the subsurface soil in the area, a total of thirteen vertical electrical soundings (VES) using modified Wenner array method called specialized engineering spread was used. This method also revealed a three to four earth layer model which the resistivity of the first layers ranging between 23 and263Ωm, second layers between 52 and 376Ωm, the third layers between 37 and 1874Ωm, while the fourth layers ranges between 470 and 2170Ωm. The depth ranges for the layers showed that the first layers has a depth range between 0.6 and 1.73m, the second layers with range between 1.7 and 8.9m, while the third layers was between 3.9 and 5m. Columnar sections were also generated to further look into the variations in the resistivity within the depth penetrated. Results obtained from various techniques adopted revealed the suitability of the second and third layers for the burial of the storage metallic tank. But with layer three most suitable.
Keywords: Electrical resistivity,Corrosivity Isopach map, Geoelectric layer, Steel pipe, Rust
| DOI: 10.17148/IARJSET.2018.51112