An assessment of the ground water quality was carried out in Ese Odo local government area of Ondo State, southwestern Nigeria. The study was aimed at examining the various samples of ground water and the quality of the ground water as it relates to drinking and irrigation purposes. Forty-Five ground water samples were taken from boreholes and open wells and analyzed for physical, chemical and biological properties. The results were compared with World Health Organization standards. The usefulness of these parameters in predicting ground water quality characteristics were studied and water quality index was determined from these parameters. In assessing the water for irrigation uses, indices such as percent (%Na), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI), Kelly’s ratio (KR), magnesium ratio (MR), equivalent salinity concentration (ESC) and Wilcox plot were used.   The result obtained shows that the water studied has a mean value of 2.8 NTU for turbidity, 7.3 for pH, 294 μS/cm for electrical conductivity, 52mg/L for total dissolved solids, temperature 28.3°C, total hardness 41 mg/L, chloride 38.3 mg/L, calcium 15.8 mg/L, 5.64 mg/L for magnesium, nitrate 1.47mg/L, sulphate 51.7 mg/L, bicarbonate 15mg/L. Zinc, iron, manganese have mean values less than 1mg/L. The results indicated all the physicochemical parameters are within the recommended levels set by World Health Organization (WHO). Although traces of heavy metal and mineral oil contaminations are observed some of the samples. All the samples are plotted on the “Excellent irrigation class” of Wilcox plot with good/excellent irrigation indices. Consequently, the groundwater in the study area is good and suitable for drinking and irrigation purposes.

Geochemical, geotechnical, and geophysical investigations were carried out along Migmatite gneiss underlain Iyere -Ipele pavement (under construction) in order to assess the suitability of the imported subgrade soil. Also static water level (SWL) was obtained from five open wells along the highway. The geotechnical tests include specific gravity, grain size analysis, consistency limits, consolidation, compaction, and California Bearing Ratio (CBR), and shear strength; while geochemical tests were analyzed using X-ray fluorescence and Atomic Absorption Spectrophotometer (AAS). The results show that SiO2, Al2O3 and Fe2O3 constitute an average of 46.2%, 23.30% and 26.54% respectively of the soils chemical composition. The silica-sesquioxide ratio of the samples ranges from 0.89 to 0.96 and classified as true laterite. The topsoil along the highway is made of moderately competent/competent soil with resistivity ranging from 298 -924 ohm-m and thickness of 3.1 -8.2 m. The SWL varies from 3.3 -5.5 m with an average of 4.3 m (moderately low). The soils are characterized by high California Bearing Ratio values, moderate shear strength (150 -200kpa), and unconfined compressive strength (300 -420kpa) with predominant kaolinite clay mineralogy group. The AASHTO and USCS classification system rate the soils as good and fair/good respectively.