Bamboo Leave Ash Soil Stabilization and Hydrogeochemical Assessment of a Proposed Dam Site at Okeigbo-Ifetedo South-West, Nigeria

Abstract

Soil stabilization using bamboo leave ash (BLA) and hydrogeochemical assessment of surface water of Okeigbo damsite were carried out.  Three samples each of water and soil were collected for analyses. Soil samples collected at 1.0 m depth were mixed with BLA in proportion of 2%, 4%, 6% and 8% respectively and tests such as NMC, grain size, specific gravity, CBR, compaction and UCS were performed on them. Results showed that NMC ranged from 14.3% to 20.1%, the PI from 19.28% to 28.26%, LS from 10.7 to 15.0%.  Soaked CBR of sample 1 ranged from 12% to 14%, sample 2 from 3% to 7% and sample 3 from 3% to 9%, shear strength of sample 1 from 25.11 to 31.64 kpa, sample 2 from 12.70 to17.80 kpa and sample 3 from 31.49 to 38.73 kpa, MDD of sample 1 ranged from 1923kg/m³ to 1968kg/m³ and OMC from 13.2% to 12.0%, sample 2 MDD from 1545kg/m³ to 1623kg/m³ and OMC from 22.5% to 20.5% for sample 3. The addition BLA improves the geotechnical properties at optimum of 4% by weight of the soil. Hydrogeochemical involves determination of temperature, pH, EC, hardness, Ca²⁺, Al³⁺, Mg²⁺, Mn²⁺, K⁺, Cr⁶⁺, Fe⁺, Cu²⁺, Na⁺, Cl^-, HCO₃^- , NO₃^- _, SO₄^2- and PO₄^3-  in water samples. The pH value ranged from 6.77 to 7.44, EC ranged from 5.20 to 49.90 µs/cm, hardness, 52.97 to 57.12, i dominant ions are Ca²⁺ and HCO₃^-. The result of physico-chemical analyses revealed surface water samples are not potable