Geotechnical Characterization of some Clayey Soils for Use as Landfill Liner

Waste management is one of the major challenges faced by municipality officials, public health engineers and environmentalists in their quest to protect and preserve our environment. Construction and operation of an engineered sanitary landfill ensures proper waste management with the protection of human and ecosystem health. This paper presents the results of geotechnical investigation carried out on clayey soils from three selected pottery areas in Oke Ogun, Oyo State; to assess their suitability for use as landfill liner. Samples were collected at three locations namely: Ajetunmobi village, sample A; Adegbite area, sample B; and Arigangan area, sample C. Basic index characterization tests conducted on the samples revealed percentage fines for samples A,B and C were 32.7%, 28.3% and 37.0% respectively. Specific gravity ranged between and 2 \ub7 71 and 2 \ub7 74. Sample A had Cation Exchange Capacity (CEC) value of 10.58 milli-equivalents/100g (Meq./100g), sample B had CEC value of 11.76 (Meq./100g) and sample C had CEC value of 12.18 (Meq./100g) Geotechnical tests conducted on samples resulted in hydraulic conductivity (k) of 1.86 7 10-10m/sec for sample A ; 4.12 7 10-8m/sec for sample B and, 2.60 7 10-10m/sec for sample C. The results obtained from the study show that sample A is the best material for a landfill liner based on the hydraulic conductivity criterion, however all the other samples are also useful and can be improved by addition of little percentage of bentonite. The compaction and compressibility characteristics needed in the specifications for the construction and operation of an engineered landfill using these clayey soils are presented

The Stabilization of Weathered Dolerite Aggregates with Cement, Lime, and Lime Fly Ash for Pavement Construction

An experimental program was performed on weathered dolerite specimens stabilized by adding varying percentages of cement (4, 8, 12, and 16) % and lime (6 and 12) % and a combination of lime and fly ash (6% lime + 12% Fly ash and 12% lime + 12% Fly ash) % by dry weight of soil. The strength was examined under three different curing methods, namely, membrane curing (MBC), alternate moist-air curing (MAC), and water curing (WAC), by conducting unconfined compressive strength (UCS) tests. Simple polynomial and linear functions (regression models) were used to define the relationships between the variables investigated. Membrane curing (MBC) gave results close enough to the water curing (WAC) to indicate that it can be confidently used on the field during pavement construction. From the results obtained, for class B (interurban collector and major rural roads) pavement construction, addition of 8% cement was recommended for road base construction with stabilized WDA. Also the addition of 12 + 12% Lime and Fly Ash was recommended for road subbase construction with stabilized WDA. Stabilized WDA against the prejudiced myths would perform satisfactorily for base and subbase construction in both heavily trafficked and low volume roads with economic quantities of cement, lime, and fly ash in South Africa

Cement stabilization treatment of lead and naphthalene contaminated lateritic soils

This article presents an investigation on the influence of Ordinary Portland Cement (OPC) as a binder in the stabilization treatment of lateritic soil contaminated with lead or naphthalene. To evaluate the performance of the binder, the contaminated soils were tested for mechanical strength and environmental performance before and after the stabiliza­tion treatment. Results showed that the strength as inferred from the unconfined compressive strength (UCS) and cohesion values increased with the addition of the binder. Cement stabilization of the lead contaminated samples also prompted a reduction in the release of lead below the admissible limit during the leaching test. Cement stabilization of the naphthalene contaminated samples, on the other hand, could not contain the release of naphthalene below the regulatory level during the leaching test. The batch equilibrium adsorption test (BEAT) showed that cement stabilization increased the adsorption capacity of the soil for the contaminants

SPECTROSCOPIC CHARACTERIZATION OF A NIGERIAN STANDARD SAND: IGBOKODA SAND

-1 reveal the presence of quartz and that it is in the crystalline form. Bands at around 800cm -1 -822.79cm -1 and 786.23cm -1, reveal that the silica is in the form of α-Quartz. The Raman spectrum of the sample has two peaks at around 203cm -1 and 463.07cm -1 for A1 vibrational mode characteristic of quartz. These peaks reflect that the sample studied belongs to the low temperature quartz. The occurrence of the Raman shift at 463.07cm -1 supports the observation from XRD studies which establishes that the quartz observed in this work is α-Quartz. The 29 Si NMR spectrum shows a prominent signal at -107.95 ppm correlating to quartz

Contamination potential of tar sand exploitation in the western Niger-Delta of Nigeria: baseline studies

Exploitation of the tar sands in Ondo State in the Niger Delta is likely to result in some environmental contamination and adversely affect the living conditions of the farmers and fishermen in the area. Three wells were established where samples were taken at 1, 2 and 3 m depth. Although no hydrocarbon contamination was detected in the water from the surface and boreholes, saline intrusion was recorded. This study produces a baseline against which future contamination can be monitored so that preventative measures can be taken to mitigate the effects

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

Engineering properties of tropical clay and bentonite modified with sawdust

Construction engineers typically avoid the use of expansive soils as construction materials because they are usually difficult to work on and can cause structural failure. This research work investigates how the application of sawdust to tropical clay and bentonite influences their geotechnical properties in order to determine their suitability for use as landfill-liner materials for the effective containment of toxic substances from landfills. X-ray diffractometry, X-ray fluorescence spectroscopy and scanning electron microscopy were used to determine the mineralogical composition, oxide composition and microstructure, respectively, of the clay and the bentonite. A series of laboratory tests were conducted to determine the specific gravity, Atterberg limits, compaction, unconfined compressive strength and permeability characteristics of the clay and the bentonite for varying proportions of sawdust application. Generally, increasing the percentage of sawdust caused a reduction in its specific gravity, maximum dry unit weight and unconfined compressive strength, while it caused an increase in the optimum moisture content and permeability of the modified clay and bentonite. The clay and bentonite both have a sufficiently low permeability that satisfies the hydraulic conductivity requirement for use as clay liners. Eight percent sawdust application to a clay having similar properties as that in this study is recommended as an economic way of modifying it – with the potential of improving its adsorbent property – for use in landfill-liner systems in order to prevent the toxic substances leaching from the landfills, thereby protecting the environment and public health

Pollution vulnerability and health risk assessment of groundwater around an engineering landfill in Lagos, Nigeria

Solid wastes disposal, through the use of non-sanitary landfill facility has tremendous health impacts on man and environment, yet without regard to environmental consequences, the use of controlled dumpsite is at best a common practice in underdeveloped countries. The paucity of data on modelling of potential vulnerability of neighboring aquifer to the pollution from Soluos dumpsite (a non-engineering landfill) necessitate the study of the use of a model DRALTC (modified DRASTIC) on the estimation of vulnerability of groundwater to dumpsite pollution and associated health risks. Six hydrogeological factors: Depth to water, net recharge, aquifer media, distance of wells to dumpsite, topography, and clay content, were involved in the modification of the model (DRALTC) which helps in characterizing the hydrogeological setting of the study area and estimation aquifer vulnerability. Sodium adsorption ratio (SAR) and permeability index (PI) were used to analyse the data generated in this study. The health risk indices (HRI) were also estimated for trace metals in the groundwater samples. The pollution vulnerability ranged between (161 and 175) moderate and high groundwater pollution potential. SAR results observed in this study reveal 25% excellent, 20 % good, 10% doubtful and 45% unsuitable. The order HRI observed was Cd > Zn > Cu > Ni > Pb for adult, while Cd > Cu > Ni > Zn >Pb trend was found for children, though the HRI value for all the metals investigated were within the safe limit (HRI < 1.0) suggesting no health risk