In Nigeria, the reliance on sanitary landfills is a common phenomenon in the disposal of waste materials. Lack of capital and appropriate technology for environmentally friendly waste management practices has left most places like Lagos ‘megapolitan’ in Nigeria to rely of landfills for solid waste disposal. And in most cases the landfills are not properly engineered and operated to accepted world standards. The study presents the measurement and analysis of the water samples were collected from two major dumpsites in Lagos, the Olusosun and Solous dumpsites and adjoining areas. Landfill Diversion
Findings revealed samples from Solous dumpsite did not confirm pollution from leachates thereby suggesting that the water from the nearby wells is portable and can be used consumed. On the other hand, analysis of water samples from Olusosun dumpsite and surrounding areas confirmed the presence of feacal coliforms during microbiological analyses, suggesting that the water sample collected from Olusosun is not suitable for consumption. Invariable samples collected from Olusosun dumpsite and adjoining areas should undergo further treatment before consumption due to the presence of other micro organisms.
Keywords: Leachates, groundwater, landfill, municipal solid waste, Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) European Scientific Journal May edition vol. 8, No.11 ISSN: 1857 – 7881 (Print) e – ISSN 1857- 7431 2 Introduction: The problems associated with solid waste and its management has been the focus of considerable environmental attention during the last quarter of the twentieth century as communities the world over have begun to recognize the hazards that its management entails. Landfill Diversion
Over many decades, landfilling has been favoured as a method of waste disposal for a number of reasons, often because it is probably the cheapest available method and also as a result of the availability of holes in the ground. Landfiling with municipal solid waste (MSW) is a common practice in many countries of the world. It is used to reclaim ‘void spaces’ created as a result extractive operations, particularly the reclamation of quarry sites which generate more derelict land than any other form of industrial activity. Properly managed, derelict voids can be reclaimed by a process of sanitary, landfilling, ultimately bringing the land back into productive use and providing much of the needed waste disposal sites (Adesina, 2000). Sanitary landfilling as a technique has replaced the pen tipping which characterized landfill disposal before 1950s. Landfill sites are now commonly ‘engineered’ and operated so that wastes are placed in layers 1- 2m deep and compacted by metal-wheeled vehicles. An uncontaminated cover material, usually soil, is spread over the wastes daily and blowing litter and pests control (Douglas, 1992). Groundwater forms that part of the natural water cycle present within underground strata or aquifers. Landfill Diversion
Unfortunately, groundwater is all too often considered out of sight and out of mind. Of the global quantity of available freshwater, more than 98% is groundwater stored in pores and fractures of rock strata. Groundwater is also an important source for industry and agriculture uses as well as sustaining rivers experiencing low flows. Groundwater is not only abstracted for supply or river regulated purposes, it also naturally feeds surface-waters through springs and passages into rivers and it is often important in supporting wetlands and their ecosystems. Removal or diversion of groundwater can affect total flow. A reduction in either quality of quantity of the discharging groundwater can significantly influence surface water quality and the attainment of water quality standards. Surface water and groundwater are therefore intimately linked in the water cycle, with many common issues. The protection of groundwater quality is of paramount importance. Landfill Diversion
If groundwater becomes polluted, it is difficult, if not impossible, to rehabilitate. The slow rate of groundwater flow and low microbiological activity limit any selfpurification. European Scientific Journal May edition vol. 8, No.11 ISSN: 1857 – 7881 (Print) e – ISSN 1857- 7431 3 The risk of groundwater pollution is increasing both from disposal of waste materials and from widespread use by industry and agriculture of potentially polluting chemicals in the environment. Pollution can occur whether discrete, point sources, such as from the landfilling of wastes. One of the dreaded consequences of rapid urbanization has been the problem of solid waste management, particularly in terms of environmental nuisance combined with the health hazard and its implications. Waste management has therefore become an endemic problem that characterizes Nigerian cities. Landfill Diversion
Coupled with the lack of capital and appropriate technology for environmentally friendly waste management practices has left most state governments like Lagos relying on the use of landfills for solid waste disposal. And in most cases the landfills are not properly engineered and operated to accepted world standards. Landfill practices because of its cost effectiveness have become the most favourable choice particularly in Lagos, after previous attempt at incineration failed. The untreated rubbish being placed in the landfill voids comprises biodegradable solids such as vegetable, paper and metal, inert solids such as glass and plastics and other unclassified materials constitute a great threat to underground water quality. Such contamination occur through leakage; which is formed when rain water infiltrates the landfill and dissolves the solute fraction of the waste and the soluble product formed as a result of the chemical and biochemical processes occurring within the decaying wastes. Landfill Diversion
The resultant effluent will however impose their Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) on the ground water. Recent studies have shown that the COD and BOD of such wastes may be in the region at 12,000mg/L and 700mg/L respectively with the concentration of inorganic chemical substances like ammonia, iron and manganese varying according to the hydrology of the site and chemical and physical conditions within the site. The concentration according to in recently emplaced wastes has been put as: Sulphate 460mg/L, Magnesium 390mg/L, Chloride 2100mg/L, Iron 160mg/L, Sodium 2500mg/L and Calcium 1150mg/L. Also a tip of 1000m3 of rubbish has been calculated to yield 1.25 tonnes of potassium and sodium, 0.8 tonnes of calcium and magnesium, 0.7 tonnes of chloride, 0.19 tonnes of sulphate and 3.2 tonnes of bicarbonate (Brown et al, 1992). Thus, it can be appreciated that disposal of waste in landfill sites can produce large volumes of effluents with a high pollution potential. Landfill Diversion
For this reason, the location and management of these sites must be carefully controlled. Such measure is becoming increasingly necessary in Lagos, where landfill method is European Scientific Journal May edition vol. 8, No.11 ISSN: 1857 – 7881 (Print) e – ISSN 1857- 7431 4 widely used (Groundwater Resource in Lagos State., undated), with living residences fast developing in the vicinity of the landfills and in some situation share fences with landfill sites and water supplied from shallow and deep wells/boreholes) to find immediate present and future solutions to the landfilling resultant problems.
It is against the foregoing that study sought a review of groundwater pollution from waste disposal site in Lagos, with a particular focus on the two major landfill sites, which are Olusosun and Solous sites. The study therefore intends to measure and analyze the impact of landfilling leachates on underground water, with a view to ascertaining whether the leachates from the landfill site have polluted underground water or not and consequently proposed new provisions for future site selection. Landfill Diversion