MEASUREMENT AND ESTIMATION OF SOIL WATER CHARACTERISTIC CURVE FOR FOUR UNSATURATED TROPICAL SOILS

Infrastructures are mostly built on unsaturated soil in the tropical region such as Nigeria, yet soil investigations and designs are based on saturated soil mechanics owing to difficulties associated with soil suction measurements using direct methods such as pressure plate extractor, triaxial testing equipment for testing unsaturated soil, etc. Soil water characteristic curve is an important parameter for estimating unsaturated soil property function. This research considered an indirect method (filter paper) of laboratory soil suction measurement (which is relatively simple, fast and inexpensive) and predictive correlation equations for estimating soil water characteristic curve from index properties of soil for four unsaturated tropical soils of Nigeria, three predictive correlation equations were used in this research namely; Navid et al model (2012), Zapata et al model (2000) and Witczak model (2006), the soil water characteristic curve constant parameters computed from these models were fitted through either Van Genuchten model (1980) or Fredlund & Xing model (1994). Results of air entry values of soils from experimental work and predictive correlation equations were in close range which indicated that in spite of the difficulties experienced in performing laboratory suction test, the predictive correlation equations such as the ones used in this research were found to be proper for estimating soil water characteristic curve

SITE REMEDIATION IN NIGERIA: PROVEN AND INNOVATIVE TECHNOLOGIES (RECOVERY OF FREE HYDROCARBON FROM SOIL/GROUNDWATER)

This research is concerned with geo-environmental impact assessment and remediation of contaminated soil/groundwater. The specific study site is Baruwa community (Latitude 06˚ 35' 12'' N, Longitude 03˚ 16' 21'' E), in Alimosho Local government area of Lagos state, Nigeria. The estimated 65,000 people of Baruwa own about 350 hand dug wells for domestic water supply; more than 200 of these wells are at present, under lock and key because of the oil seepage from leaking underground NNPC (Nigerian National Petroleum Corporation) pipeline. The Geoenvironmental Engineering research group in F.U.T.Akure, started Geoenvironmental site assessment, geotechnical, background and natural attenuation studies for the site in 2006. This has enabled delineation of the contaminated zone. Eight (8) hydrocarbon recovery/monitoring wells (W16, W17, W18, W19, W20, W42, W43, and W44) and two bore holes (W401 and W402) were used for the pilot recovery test. Existing contaminated water supply wells were used as hydrocarbon recovery/monitoring wells to minimize cost. Two boreholes were installed for soil vapour extracting and gas surveys in addition to the eight existing wells within the 100m x 100m designated pilot test area. We have already established that water supply wells are covered by pure phase leaking hydrocarbon products from the underground pipes. Tested well waters had been found to be as much as 95 percent petrol and up to 600 mm thickness of free hydrocarbon product on top of the ground water. Volumetric characterization of the pure phase hydrocarbon using Oil/Water Interface meter/ areal measurements and monitoring together with assessment of various technologies (Natural Attenuation, In Situ Chemical Oxidation and Bioremediation) for remediation was implemented for this site

Assessment of the Engineering Properties of Modified Asphalt Using Aluminium Dross as a Filler.

Aluminum dross waste creates environmental burden for manufacturers and hence the need for its re-use. This experimental research assessed the engineering properties of modified asphalt using aluminium dross as a filer material. The aluminium dross used was obtained from a steel manufacturing industry. Elemental composition of the oxides was done using XRF equipment. Sieve analysis of the aluminium dross and the coarse aggregate was also assessed. Additionally, ductility, penetration, ball and ring and Marshall stability test were used in achieving the aim of this research. The outcome of the research revealed that 10-20% addition of the aluminium dross improved the stability of the modified asphalt. Physical observation revealed that the utilization of the waste stiffened the modified asphalt. The result showed that the addition of aluminium dross reduced the VMA. This will also increase the asphalt mix flushing. Additionally, at higher percentage addition of the waste the stiffness of the asphalt mix increases especially at a higher temperature. The use of this material will help in the reduction of solid waste and reduce the cost of management while reducing the cost of pavement construction in track with the trash to treasure drive