Preliminary Determination of Subsurface Soil Profiles in Akenfa Community, Bayelsa State, Nigeria

This study aims at establishing the sub-soil types and profile to ascertain the geotechnical characteristics of the underlying soils in Akenfa in Yenagoa, Yenagoa Local Government Area of Bayelsa State, Nigeria and recommend appropriate foundation design and construction of projects in the area. Three (3) geotechnical boreholes were drilled at the site to obtain baseline data on geotechnical properties of the soil and water level monitoring, the boreholes were advanced with the use of a cable percussion boring rig and were terminated to a maximum depth of 30m. The particle size distributions of a number of representative samples of the cohesionless soils were determined by sieve analysis. The results show that the samples are low to medium plasticity silty clay. The lithology revealed intercalations of clay and sand in thin layers to a depth of 2.0m below the existing ground level. Underlying this clay is a stratum of loose to medium dense sand and dense sand. The sand is well sorted grading from fine to medium as the borehole advances. The laboratory analysis showed that the silty clay has undrained shear strength of 48 kPa. The loose sand has a maximum SPT (N) value of 12 while the medium dense sand has maximum SPT (N) value of 28. Considering the nature of the civil structures to be sited in the area, it is anticipated the load and the moderate compressibility of this near surface silty clay and the underlying loose silty sand be supported by means of raft foundation founded within the clay layer. It is recommended that studies on the geotechnical characteristics of the area be carried out as it provides valuable data that can be used for foundation design and other forms of construction for civil engineering structures in order to minimize adverse effects and prevention of post construction problems. Keywords: Subsoils, geotechnical, foundation, engineering structures, Akenf

www.ijcrar.com Geotechnical Evaluation of Subsoil for Foundation Design Considerations in

geo-technical, lithology, foundation, Okochiri The study establishes the sub-soil types and profile to ascertain the geotechnical characteristics of the underlying soils in Okochiri, Okrika, Rivers State, Nigeria for appropriate foundation design considerations in the area. Borings were accomplished using a percussion rig with the aid of augers. Representative samples were analyzed in the laboratory in accordance with relevant geotechnical engineering standards. The study revealed that the topsoil is underlain by firm clay of moderate compressibility with Cu: 56-64KN/m 2 (about 10m thick). Underneath this layer, is loose sandy layer with phi =28-29 o (thickness 8m) overlying a poorly sorted medium dense sand layer with Phi between 30 0 to 35 0. The drainage characteristics of the sub-soils are low. The allowable bearing capacity profile of the sub-surface shows moderate bearing Capacity characteristics (1.5m:120KN/m 2). Settlement predictions based on a loading of 300KN/m 2 indicated a settlement of < 100mm. Pile foundation is therefore recommended for consideration. This study therefore, has provided valuable data that can be used for foundation design and construction of future civil engineering structures in the study area

Concentrations of heavy metals in soil and water receiving used engine oil in Port Harcourt, Nigeria

The concentrations of heavy metals (Cu, Ni, Pb, Zn) in soils and water receiving used engine oil were investigated. Soil and water samples were collected at discharge and control points at each study site. The heavy metals were analyzed using atomic absorption spectrophotometer. The results show that about 80% of used engine oil was disposed of directly into the environment and 20% was recycled via use in civil works. The concentrations of metals in test soil and water samples exceeded permissible limits. The concentrations of heavy metals ranged from 20 µg/g (Ni) to 493 µg/g (Pb) in soil and 0.019 mg/l (Ni) to 0.147 mg/l (Pb) in water. It was suggested that curbside collection and re-refining of used engine oil should be encouraged and appropriate legislation should also be put in place to prevent widespread pollution of the environment by these metal ions