Plasticity and Compressibility Characteristics of Lateritic Soil From Southwestern Nigeria

Plasticity index and coefficient of compressibility amongst other characteristics were determined for some lateritic soil samples of Southwestern Nigeria with a view to establishing the relationship between their plasticity and compressibility as well as predicting their in-situ compressibility and also determine the effect of the parent rocks on the plasticity and compressibility.  Two study areas were chosen in Ibadan, Southwestern Nigeria where ten disturbed and ten undisturbed samples each were collected.  The disturbed samples were subjected to a number of geotechnical tests: grain size, distribution analysis, specific grant and consistency test.  The undisturbed samples were subjected to consolidation test.   The study revealed the rock type in study area A to be quartzschist and area B to be granitic.  The specific gravity of the soil grains ranged between 2.48 and 2.72; while the plasticity index value was between 9.7 and 21.4%.   Coefficient of consolidation ranged between 29.39mm2/min and 32.56mm2/mm with coefficient of volume compressibility between 1.08 x10-3 m2/KN and 1.94 x10-3m2/KN.  The soil samples were generally well-graded reddish brown, sandy-silt-clay of medium plasticity and compressibility with dominant kaoline clay mineral in the quartzschist derived soil while the dominant clay mineral in the granite derived soil is illite.  The most influenced parameter of the parent rocks was the coefficient of compressibility, which revealed the samples of the two study areas to be suitable for construction work as well as landfill site with little compaction. &nbsp

Integrated Geophysical Mapping to Determine Depth to Basement at Awa Ijebu, Southwestern Nigeria

Integrated surface electrical resistivity, magnetic survey and horizontal profiling were conducted at Awa Ijebu, South-western Nigeria, to delineate the probable depth of basement and determine geological anomalies therein.  Wenner resistivity profiling and magnetic data were acquired at intervals of 5.0m along four traverses of 100.0m long and five traverses of 250.0m long respectively.  The resistivity data obtained revealed three subsurface geologic layers: top soil, weathered bedrock and intrusive pegmatite rock. The distinct high resistivity zone is interpreted as the intrusive pegmatite rock while the low resistivity zone is interpreted as fault zone.  The magnetic survey result revealed that there was a high magnetic anomaly trending Southeast – Northwest direction and dipping westward. &nbsp

EXPERIMENTAL INVESTIGATION OF LEACHATE CONTAMINATION ON GROUNDWATER EXPLORATION IN BASEMENT COMPLEX AREA

A total of ten groundwater samples were collected from wells around the site of Orita Aperin refuse        dump, Ibadan, Southwest, Nigeria, to determine the extent of groundwater contamination. The results        of   the  hydro-chemical   analysis   show  that   groundwater   samples   collected  from wells   away from the        leachate revealed comparable W.H.O. standard values for groundwater consumption. Most obvious        parameters   are:  increase   in   total  hardness   (between   184.8   and   239.6mg/l   for   samples   near   the        leachate;   74   and   102mg/l   for   samples   far   from   the   leachate),   low   calcium   (ranged   from   46.2   to        78.7mg/l for samples near the leachate; 3.7 to 32.8mg/l for samples far from the leachate), magne-        sium (ranged from 5.1 to 30.3mg/l for samples near the leachate; 3.4 to 21.5mg/l for samples far from        the leachate), chloride (between 20 and 224mg/l for samples near the leachate, 32 and 174mg/l), and        sulphate content (ranged from 9 to 76mg/l for samples near the leachate; 25 to 38mg/l for samples far        from the leachate); while high values of TDS (in samples A and C and I), nitrate (in samples A and C)        and chloride (in samples A and I) which were due to the effect of leachate on the water quality result-        ing to contamination of these wells. Thus, adequate treatment should be carried out on wells located        close to the leachate before consumption.&nbsp

Delineation of Leachate Plume Migration Using Electrical Resistivity Imaging on Lapite Dumpsite in Ibadan, Southwestern Nigeria

A geophysical investigation involving 2D resistivity survey was carried out on Lapite dump site that has been in operation since 1998 in ancient city of Ibadan, Southwestern Nigeria. The aim was to map the conductive leachate plume and extent of migration of leachate plumes in the subsurface for possible groundwater contamination. The 2D resistivity survey was carried out using Campus Tigre model resistivity meter with Wenner array configuration of electrode spacing distance ranging from 5 - 25m. A total of nine (9) 2D resistivity profiles with length ranging between 80 and 120 m were conducted within the dump site. A control profile of 2D resistivity survey was also carried out at about 300 m away from the dump site. The obtained resistivity data was interpreted using both RES2DINV and RES3DINV respectively. The 2D and 3D inverse resistivity models of the subsurface revealed the extent of leachate plumes with resistivity values less than 10 Ωm and allowed the location of leachate, clay soil, bedrock and seepage path from the dumpsite to be clearly delineated. There may be possible contamination of shallow groundwater system in the nearest future if proper mitigation measures are not taken into consideration at the dumpsit

Assessment of groundwater contamination around active dumpsite in Ibadan southwestern Nigeria using integrated electrical resistivity and hydrochemical methods

Investigation of groundwater contamination due to leachate migration in a solid waste disposal site was done using both geophysical and hydrochemical methods. The main goals were to delineate groundwater contamination due to leachate percolation and thus assessment of quality of groundwater from nearby hand-dug wells bordering the dumpsite for drinking purpose. A total of ten resistivity traverses were acquired within and outside the dumpsite using Wenner configuration with constant electrode separation ranging from 5 to 25 m. The 2D resistivity data were processed and inverted using RES2DINV and RES3DINV softwares, respectively. Geochemical assessment of groundwater samples were carried out according to APHA standards while hydrochemical facies of the sampled groundwater was evaluated using Piper Trilinear software. The inverse resistivity models of the subsurface from 2D and 3D imaging revealed low resistivity value less than 10 X m suspected to be leachate while 3D inverse sections allowed delineation of leachate, weathered layer, bedrock and seepage path from the dumpsite. The extent of migration was more pronounced in the southern part of the dumpsite, hence possible contamination of shallow groundwater system as dumpsite ages. The results of physico-chemical analyses showed the groundwater samples to be within the limits of WHO/NSDWQ for drinking purpose. However, higher values of concentrations of most analyzed parameters were noticed in well 1 due to its nearness to dumpsite and well 10 due to agricultural activities, respectively. Interpretation of Piper diagram showed CaHCO3 to be dominant facie in the area while alkaline earth metals (Ca2þ; Mg2þ) and weak acids (HCO3 -, CO3-) are dominant cations and anions during both climatic seasons. Groundwater in the study area is of hard, fresh and alkaline in natur

Investigation of incessant road failure in parts of Abeokuta, Southwestern Nigeria using integrated geoelectric methods and soil analysis

A flexible pavement devoid of discontinuities allows for smooth movement of a vehicle load on the roadway. This study involved the use of integrated geoelectric methods comprised of 1D and 2D Electrical Resistivity Tomography (ERT) as well as soil analysis to investigate causes of unceasing road failures along busy Camp—Alabata Road, Abeokuta, Southwestern Nigeria. Four road sections (two failed portions and one fair section and one good section) were identified along which four resistivity traverses were established along the investigated roadway. Four 1D Vertical Electrical Sounding (VES) points were also carried out on the 2D ERT lines. Apparent resistivity data were measured along the four traverses using Schlumberger and Wenner arrays with the aid of a Campus Ohmega resistivity meter. The VES and 2D resistivity data were processed and inverted using WinResist an

Corrosion Inhibition Behaviour for Mild Steel by Extracts of Musa sapientum Peels in HCl Solution: Kinetics and Thermodynamics Study

Staff PublicationThe inhibition of the corrosion of mild steel by acid extract of Musa sapientum peels in 1M HCl was investigated using weight loss method. The results showed that the corrosion rate of mild steel in 1M HCl decreases with increase in concentration of the extracts and the values were in the range 0.013021 - 0.002127 ghr-1 cm-2 . The inhibition efficiency increases progressively as the concentration of the extracts increases up to about 4% (v/v), above which, further increase in extract concentration did not cause any significant change in the inhibition efficiency. Effects of temperature on the inhibition efficiency of the extracts showed that inhibition efficiency decreases with increase in temperature. Activation energy (Ea) was found to be 61.60 Kjmol-1 for 1M HCl and increases to 66.72Kjmol-1 in the presence of Musa sapientum extract. The values for enthalpy of activation and entropy were all positive indicating the endothermic nature of the mild steel dissolution process. Calculated Gibbs free energy was in the range -9.43 to -8.99KJ. Kinetics of the reaction in the presence of the extracts revealed that it follows a first order reaction and the half-life increases as the concentration of the extracts increases suggesting that inhibition efficiency increases with increase in the concentration of the extracts. Preliminary investigation of the phytochemical constituents showed that Musa sapientumcontains tannin, flavonoid, terpenoid and some other compounds in trace constituents

Investigation of Sub Soil Corrosion Using Electrical Resistivity Method: Federal University Oye Ekiti Phase II Campus as a case study

Electrical Resistivity survey was carried out with the aim of identifying the degree of soil corrosion associated with the sub soil of the Federal University Oye Ekiti phase II. The sub soil resistivity of the area was surveyed and evaluated using Ohmega resistivity meter. The sub soil resistivity parameters were used to delineate the degree of the sub soil corrosion. Four electrodes were inserted into the soil/rock using the Wenner profiling, vertical electrical sounding and Dipole- Dipole array along the traverses with a spacing of 5m and n =1 to 5.In this method, artificially generated electric current(I) was injected into the ground via two current electrodes while the resulting potential difference (V) is measured by another pair of electrodes. The survey revealed that the Southwest and Northwest regions of the study area were associated with high resistivity (200-500 Ω-m).This implies that the soil structure of the region is not corrosive, while the southeast region was associated with low resistivity (20-80 Ω-m) value which implies that the sub soil structure is corrosive. The degree of corrosion increases from the western to eastern part of the study area which may be due to bedrock topography. Of all the layers investigated, the topsoil layer is highly corrosive compare to other layers