Accessing of the Effect of Sand Excavation on the Environment
Chapter One
Objectives of the study
The aim of this study is to assess the effects of sand excavation on the environment of Abraka-Eku along Ethiope River. In order to achieve the above stated aim, the following specific objectives were considered;
- To assess and compare the soil component mined most for construction.
- To measure and analyse the size of pits where pit sand and gravel are collected.
- To assess, measure and evaluate the width and depth of rivers at sampled extraction points.
- To evaluate the positive and negative environmental impacts of mining river sand, pit sand and gravel for urban development.
- To make recommendations on sustainable mining of soil which reduce negative impacts on the environment.
CHAPTER TWO
REVIEW OF RELATED LITERATURE
Introduction
Soil is an important source of raw materials such as clay, sand, gravel and minerals. It is a non-renewable natural resource with potentially rapid degradation rates and extremely slow formation and regeneration processes (Mwangi, 2007). Sand is a cheap and heavy resource consisting of very small pieces of rocks and minerals, a result of weathering that forms beaches and deserts. Gravel is a heavy and cheap commodity made of small weathered stones used to make surface for paths and roads. The resource’s compressibility, plasticity and textural properties have been valued in construction for hundreds of years. The ability of soil to be moulded and its cohesion properties were the basis for using it to build the earliest houses (Goddard, 2007). Saviour (2012) defined soil as a mineral which protect the environment, buffer to strong tidal waves and storms, habitat for crustacean species and marine organisms. The mining of pit sand and gravel can be done on open areas, beaches, inland dunes, mountain sides while river sand is extracted from riverbeds and banks. Unscientific mining has led to degradation accompanied by subsistence and consequential mine fires, severe ecological imbalance around mining areas (Saviour, 2012). The practice is becoming an environmental issue as the demand for sand as an important mineral resource is increasing in the construction industry.
Goddard (2007) realised that decisions on where to mine, how much and how often requires definition of reference state and sand budget. Reference state is the minimal acceptable physical and biological condition of a channel (Goddard, 2007). Though reference state is difficult to determine, a general knowledge of fluvial processes is necessary to minimise detrimental effects of mining. A sand budget for a particular extraction area for example a stream or open area should be done to first determine the amount of sand that can be removed without causing degradation and erosion. Before doing a sand budget, consider mining methods to be used, particle size, characteristics of the sand, riparian vegetation and magnitude as well as frequency of hydrologic events after disturbance.
Therefore minimisation of the negative effects of sand and gravel mining requires a detailed understanding of the response of site to these disturbances (Goddard, 2007).
Hill and Kleynhans (1999) discussed various methods of mining sand and gravel. Dry pit mining is a method used when sand is extracted above water table from a dry stream bed and exposed bars using conventional bulldozers, scrapers and loaders. Wet pit mining involves extraction of sand and gravel from below water table stream channel or a perennial river using hydraulic excavator or dragline. Dewatering can be done in advance to allow easy excavation though this depends on deposit thickness, permeability of the ground as well as after use and restoration requirements. Bar skimming or scalping is a method used when only the top layer of soil is removed by scraping without excavating below summer water table which is the level of underground water in summer season (Hill and Kleynhans, 1999).
Sand excavation and gravel extraction in the world
Sand excavation and gravel extraction are a worldwide activity in both developed and developing countries as was realised by Draggan (2008). Industrial sand and gravel are produced, processed and used in construction and industry all over the world. The leading nations in mining and processing sand and gravel are United States of America, Australia, Austria, Belgium, Brazil, India, Spain, Nigeria, Kenya and Nigeria. As a cheap and readily accessible resource many companies are involved in its mining both legally and illegally without considering the damage they are causing to the environment (Draggan, 2008).
Soil mining and gravel extraction is a common activity in United States of America. A publication by Schaetzl (1990) showed that historically, from 1920s many states in USA relied on mining of gravel and sand for road and cement aggregate. The uses had doubled by 2008 to date. Sand and gravel are mined more than all other minerals in most States in America. According to Draggan (2008), USA is the largest producer and consumer of sand and gravel in the world as well as the leading exporter of silica sand to every region of the world. This is because it has extensive high quality deposits of the resource combined with technology to process it into any product. Construction sand and gravel are produced in all fifty states. The highest producers are California, Texas, Michigan, Minnesota, Ohio, Arizona, Utah, Colorado and Washington. They all produce about 52% of total amount of construction sand and gravel. More than a billion tonnes of sand and gravel are produced and used annually. Due to high demand in these States, some sand and gravel are still imported from Canada, Mexico, Bahamas, and Australia (Draggan, 2008).
CHAPTER THREE
RESEARCH METHODOLOGY
Introduction
This chapter discusses the author’s methodology adopted for the study. It gives a detailed account of the data collection processes employed to obtain data. The main objective was to assess the effect of sand excavation on the environment. This was done through visiting areas of extraction and key informants. The chapter clarifies the research designs and data collection instruments used in the research. Both primary and secondary data was collected and presented graphically. Statistical Package for Social Science was used for quantitative data analysis. Qualitative research designs such as questionnaires and interviews were used to collect primary data. Background information was collected through field visits by observations, taking measurements, informant interviews and questionnaire surveys. Measurement of depth, width of pits and widening of rivers at sampled collection points were taken.
Secondary data was collected through analysis of case studies and related researches in Africa and the whole world.
Research designs
Gwimbi and Dirwai (2003) defined a research design as a structure or plan of the research which provides glue that holds a project together, groups or samples, observations or measures, programmes or treatments and other aspects of methodology. There are two types of research designs, qualitative and quantitative. Qualitative is a descriptive approach when there is documentation of what is exactly said, observing behaviour or even studying written documents. A qualitative researcher gets ideas from people being studied. Data collected is presented in form of maps, photos, graphs or tables. An example of a qualitative research design is a case study. Gwimbi and Dirwai (2003) defined a case study as a strategy for doing research involving an empirical investigation of a particular contemporary phenomenon within its real life context using multiple sources of evidence. This involves a study on its own right on a specific case with a conceptual framework. A case can be a school, village, river or any phenomenon of interest. Case studies are important in decision making and for policy makers.
According to Polit and Beck (2008), a quantitative research design is an explorative non experimental, descriptive structure which involves quantifying relationships between variables. The design deals with figures and quantities. The design involves precise measurements and statistical analysis of data using computer packages. A good design should ensure that there is maximum control over factors that affect adversely the reliability and validity of research results (Gwimbi and Dirwai, 2003).
CHAPTER FOUR
DATA ANALYSIS, PRESENTATION AND DISCUSSION
Introduction
This chapter discusses results and findings of a research on assessment of the effect of sand excavation on the environment in Abraka and Eku. Data was collected through individual interviews, questionnaire survey, field measurements and observations. The researcher considered and sampled some areas where pit sand, river sand and gravel are mined around Abraka-Eku to investigate the extent of the effects caused by miners on the environment. One hundred and seventy five (175) respondents were picked as a sample to take part in the questionnaire survey. One hundred and five (105) were from Urhuoka while seventy (70) were from Ethiope villages. Interviews were conducted on people who are directly and indirectly involved in sand excavation and gravel extraction.
CHAPTER FIVE
CONCLUSION AND RECOMMENDATIONS
Introduction
The research was carried out to investigate and expose positive and negative environmental impacts of sand excavation and gravel extraction in areas surrounding Abraka-Eku where the resources are extracted for development of the city. The major objectives were to assess and find out the soil component mined most, expose positive and negative impacts of sand and gravel mining as well as recommendations to the responsible authorities at community, district and national levels.
Conclusion
The study on assessment of the effect of sand excavation on the environment revealed both positive and negative effects. It highlighted the views of affected people through questionnaires and interviews. Majority of the respondents were not happy with environmental degradation, accidents caused, waste disposed by miners, threats from illegal miners and general damage to the ecosystems.
The research justified that there are both positive and negative environmental impacts to sand and gravel mining. It revealed that river sand is the soil component mined most in construction industry because of its strength as a resource and has many uses which include building strong structures, plastering, making foundations and bricks. The researcher discovered that pits at extraction sites were increasing on every visit while rivers at sampled areas were widening and deepening. Method of mining commonly used is open pit. There are two main methods of loading being used by miners which are the use of front end loaders by licensed miners while illegal miners mostly prefer the cheaper way of hiring manual loaders who use shovels.
Sand excavation and gravel extraction are very important activities for economic development in both developed and developing world. Generally, mining disturb land surface areas, leaving huge open pits which are difficult physically and economically to rehabilitate at the time mining cease. Excessive mining leads to depletion of resources on both riverbeds and open lands. There is need for laws across the globe by high level decision makers to enforce solutions to environmental problems and implement all the stated recommendations.
Recommendations
The author listed and included recommendations to both the decision makers who are directly involved in the review of sand excavation and gravel extraction activities to make informed decisions when issuing licences and to miners considering the rate of illegal mining in the country. More recommendations are on areas which need further research.
Recommendations to decision makers
- The Nigeria government through the Department of Mines should call for a high level decision making forum involving all stake holders to discuss the problem of illegal sand and gravel mining and come up with immediate solutions which curb environmental damage.
- Effective legal framework, strict laws and legislature are important as Department of Mines with help of police force and village leadership must impose heavy fines including long jail terms to miners who extract without mining rights and licences. This is possible if trucks transporting sand and gravel pass through community leaders for inspection and verifying genuine permits to reduce use of fake documents. Confiscation of tipper trucks from illegal miners is necessary as a way of banning illegal mining.
- It is important to have an Environmental Assessment Management and Monitoring Program. Close monitoring ensures that there is proper mining and no gravel recruitment downstream.
- Deployment of 24 hour security to guard mining areas and apprehend illegal miners with help of village watch groups and clusters. Only licensed miners will be allowed into extraction sites and illegal miners will not have access. All residents must be involved in apprehending and reporting illegal miners to authorities instead of befriending them.
- Mining operations must be conducted in a manner that minimises or eliminates adverse impacts on both in stream and riparian components of ecosystems comprising of biota and habitats.
- Authorities are to strengthen laws on not allowing people to enter vulnerable areas through close monitoring of the mining activities in all areas.
- Regular inspection and roadblocks by Nigeria Police Service officers through mounting regular roadblocks next to mining areas and along roads used by trucks, setting speed traps on speeding trucks. Inspections of trucks which are not road worthy must be part of the operations.
- The Department of Mines should evolve a policy compelling miners to reinvest and repair old disused mine sites to reduce occurrence of landslides.
- Surface rights rent should be affordable to all miners to allow them to spend part of the money on repairing environmental damage due to mining operations.
- Department of Mines, District Authorities and Land Boards should ensure that farmers whose land is mined, livestock drowning in open pits and cattle dying from measles after eating dumped waste are compensated directly or indirectly by illegal miners.
- Mining Licences issued must allow harvesting river sand on braided river systems, abandoned stream channels, terraces and inactive channels. Mining activities should never be done on straight, meandering or split rivers.
- There should be construction of buffers or levees to reduce long term flooding on terraces. Soil erosion can be controlled by gabions on flat land.
- Reuse and recycling of old building material must be encouraged by authorities as a way of reducing over extraction and dumping of waste on the environment.
- Restriction of mining time and days to normal working hours that is 07:30-16:30 on week days is important to reduce illegal mining when there is tight security.
- Department of Roads and Transport with help of Nigeria Police Service should restrict tipper trucks transporting sand and gravel from using gravel roads passing through the villages. Constructing temporary roads out of villages to reduce air and noise pollution is necessary.
- Authorities are to restrict heavy front end loader equipment on riverbed which compact the ground and bring water tables near surface.
- Department of Mines should educate the public including miners on the negative impacts of continuous mining through media such as national television, radio and national newspaper, Daily News.
- Regular meetings and consultations with affected communities are important to call for their involvement in mining activities. Part of royalties can be paid to Village Development Committees so that villagers can directly benefit from mining activities in their areas.
Recommendations to miners
- All miners must draft and submit an Environmental Management Plan (EMP) in advance to ensure that potential negative impacts of their mining projects are assessed and incorporated into development plan. This becomes a prerequisite to get a permit.
- Consultations and seeking permission from interested and affected communities before mining is important as sand miners should consult chiefs, sub chiefs and Village Development Committees so as to control the size of area mined and reduce damage to the environment. Regular meetings between Department of Mines, Land board officials and village leadership can be a good platform for consultations. The village leadership will be involved in surveying and recommending the areas to be mined far from crop fields and grazing lands.
- Miners must change mining areas and not extract from same area continuously but alternate sites to reduce over extraction and environmental damage beyond rehabilitation. Mining should not be done near schools, clinics, residential or any sensitive areas like destroyed rivers.
- Limiting amount of sand and gravel mined per day will help to control depth of mining. Miners should leave 0.5 metres sand bed in situ to reduce sand depletion. The security deployed can monitor the number of trucks loaded per day.
- Controlling time of mining: not to be done throughout the year but during dry season, avoiding rainy season. This is necessary to give the land time to rehabilitate and recover. Mining time must be restricted to day time only.
- Mining should be done approaching the floodplain from one side to minimise crossing riverbed with heavy machinery. Access to river can be determined by steepness and vegetation available to avoid damaging flora. If the channel is too deep, construct access ramps.
- Access roads from public roads must be parallel to the river banks to restrict water flowing along the tracks during rainy season from forming gullies.
- Haulage roads must be a minimum of 100 metres from the banks.
- Covering sand and gravel with nets: when transporting the resources to be a prerequisite to reduce damage of other motorists’ windscreens from falling stones.
- Miners must follow the law of mining where no sand is to be extracted within 2.5 metres to 5.0 metres from the banks mostly if the river is meandering, or split.
- All miners must cover and refill pits after mining as reclamation since mitigation and restoration must occur concurrently with extraction activities to conserve biotic integrity of ecosystems.
- Reclamation of contaminated soils around all mining areas must be done by the miners. Stockpiling to be avoided on riverbeds and open areas.
- Miners must plant and establish appropriate vegetation to reduce erosion on reclaimed land.
- Compensation of farmers: whose animals drown in pits and die from measles after eating waste should be done by the miners.
- All miners must use dry pit method of mining in all their extraction activities since depth of mining can be controlled. The method should not be used on one area for too long but alternate areas of mining.
References
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