The primary goal of this study was to prepare an inventory of Pit lakes in Raniganj Coal Field (RCF), West Bengal, India along with status of water quality in these pit lakes for promoting sustainable utilisation of the Pitlake resources for socioeconomic development of the local stake holders in due course of time. A comprehensive water quality and biological monitoring programme is strongly recommended for these pit lakes in order to be able to predict and manage risks and best utilise the opportunities provided by the pit lakes for the RCF region economy.
CONTENTS
Preface
Acknowledgement
ABOUT THE AUTHORS
CONTENTS
LIST OF TABLES
LIST OF FIGURES
LIST OF PLATES
Chapter 1:
Introduction
Chapter 2: review of
LITERATURE
Chapter 3:
METHODOLOGY
Chapter 4: results and discussion
SUMMARY
REFERENCES
PREFACE
Coal mining started in the Raniganj Coalfield (RCF) area in 1774 during the British East India period. The RCF covers an area of 1530 sq km, containing about 1306 sq. km of coal-bearing land. All surface mining process creates drastic changes in the landscape. They result in the formation of large overburden dumps, huge voids and pit lake ecosystems in the mining sites. Pit lakes can form in open cut mining pits, which extend below the groundwater table. Once dewatering ceases, then groundwater, surface water and direct rainfall contribute to the formation of a pit lake.
The primary goals of this study was to prepare an inventory of Pit lakes in Raniganj Coal Field (RCF), West Bengal, India along with status of water quality in these pit lakes for promoting sustainable utilisation of the Pitlake resources for socioeconomic development of the local stake holders in due course of time. A comprehensive water quality and biological monitoring programme is strongly recommended for these pit lakes in order to be able to predict and manage risks and best utilise the opportunities provided by the pit lakes for the RCF region economy.
ACKNOWLEDGEMENT
We are grateful to Professor Ambarish Muherjee, Department of Botany, The University of Burdwan for his inspirations Dr Debnath Palit is the Assistant Professor and Head, Post Graduate Department of Conservation Biology, Durgapur Government College. His area of research includes Botany, Wetland Ecology and Conservation Biology.
Smt Debalina Kar is Research Scholar in Post Graduate Department of Conservation Biology, Durgapur Government College. She is engaged in her doctoral research work under the supervision of Dr Debnath Palit, Head, PG Department of Conservation Biology since 2010. Her area of research includes ‘Phytoremidiation of coal mined wastelands’. She has published some significant publications in peer reviewed journals.
Miss Aparajita Mukherjee is Research Scholar in Post Graduate Department of Conservation Biology, Durgapur Government College. She is engaged in her doctoral research work under the supervision of Dr Debnath Palit, Head, PG Department of Conservation Biology since 2010. Her area of research includes ‘wetland-livlihood assessment ’. She has published some significant publications in peer reviewed journals.
Sri Santanu Gupta is Conservation Biologist at Department of Conservation Biology, The University of Burdwan. He is a Senior Research Fellow under DST, GoI funded project since 2010. He has contributed the concerned scientific arena through some effective research publications and books. His area of research includes Conservation Biology, Wetlands, Biostatistics, Ecological Modelling and GIS.
[All the illustrations, tables & FIGURES used in this book are subjected
to the sole pROpERty of the authors]
LIST OF TABLES
Table 1: Distribution of study sites in Raniganj Coal Field (RCF), West Bengal, India for collecting water samples.
Table 2: Inventory list of Pit Lakes distributed over Raniganj Coal Field Area, West Bengal, India
Table 3 : Variation in RCF Pit Lake water parameters measured during the study period (2009-2012)
Table 4 : Variation in Water parameters of Pit lakes in RCF during the study period (2009-2012)
Table 5: Correlation matrix of water parameters measured in RCF Pitlakes during the study period (2009-2012)
Table 6: PC A derived results of variables corresponding to water parameters
measured in RCF pit-lakes during the study period (2009-2012)
LISTOFFIGURES
Figure 1(a,b): Map of Raniganj Coal Field, West Bengal India Figure 2: Box plot of RCF, Pit lakes Elevation (m)
Figure 3: Scattergram of Length (a) and Width (b) observed in RCF, Pit Lakes
Figure 4: Pit Lakes category observed in RCF, West Bengal India (Surface Area based)
Figure 5: Scatter plot showing the demographic properties of RCF Pit West Bengal India
Figure 6: Dendrogram plot derived from AHC analysis of RCF pit lakes based on Length, Width and Area
Figure 7: Dendrogram derived from Agglomerative Hierarchical Cluster(AHC) analysis showing the Piltlakes associations depending on water parameters measured during the study period.
LIST OF PLATES
PLATE 1: A view of Topline pond 1 (Pit Lake) in RCF, West Bengal, India
PLATE 2: A view of Topline pond 2 (Pit Lake) in RCF, West Bengal, India
PLATE 3 : A view of Topline pond 3 (Pit Lake) in RCF, West Bengal, India
PLATE 4: A view of Dhandadihi Lake 1 (Pit Lake) in RCF, West Bengal, India
PLATE 5: A view of Dhandadihi Lake 2 (Pit Lake) in RCF, West Bengal, India
PLATE 6: A view of Dhandadihi Lake 3 (Pit Lake) in RCF, West Bengal, India
PLATE 7: A view of Sital Dhemua 1 (Pit Lake) in RCF, West Bengal, India
PLATE 8: A view of Sital Dhemua 1 (Pit Lake) in RCF, West Bengal, India
PLATE 9: A view of Sankarpur Lake (Pit Lake) in RCF, West Bengal, India
PLATE 10: A view of Mahabir OCP Lake 1 (Pit Lake) in RCF, West Bengal, India
PLATE 11: A view of Mahabir OCP Lake 2 (Pit Lake) in RCF, West Bengal, India
PLATE 12: A view of : Ramnagar OCP Lake 1 (Pit Lake) in RCF, West Bengal, India
PLATE 13: A view of Ramnagar OCP Lake 2 (Pit Lake) in RCF, West Bengal, India
PLATE 14: A view of : Ramnagar OCP Lake 3 (Pit Lake) in RCF, West Bengal, India
PLATE 15: A view of Ramnagar OCP Lake 4 (Pit Lake) in RCF, West Bengal, India
Chapter l: Introduction
Pit lakes differ physically from natural lakes in having markedly higher relative depths (Castro and Moore, 2000). During active mining, surface water is diverted around open pits, and perimeter and/or in- pit dewatering pumps are used to control groundwater inflow and direct rainfall. Pit lakes form when the pumps are shut off and post mining drainage of surface/groundwater and precipitation begin to accumulate inside the inactive pit. Depending on the size and availability of suitable fill, backfilling open pits can be impractical and prohibitively expensive. In such cases, a pit lake forms and the mine operators are saddled with ensuring that it does not pose environmental and safety risks.
Coal mining started in the Raniganj Coalfield (RCF) area in 1774 during the British East India period. The RCF covers an area of 1530 sq km, containing about 1306 sq. km of coal- bearing land. All surface mining process creates drastic changes in the landscape. They result in the formation of large overburden dumps, huge voids and pit lake ecosystems in the mining sites. Pit lakes can form in open cut mining pits, which extend below the groundwater table. Once dewatering ceases, the groundwater, surface water and direct rainfall contribute to the formation of a pit lake. Coal mining in RCF has produced pit lakes that range in area from <1 to 70 ha surface area, <10 to 70 m depth, 5-80 years in age, water quality and the extent of remediation from none to extensive. RCF is the main coal mining region of ECL. Historical and ongoing open cast mining operations have created a number of pit lakes, the oldest nearly 100 years old.
Consequently, pit lakes can be seen to represent either a significant liability or a water resource to mining companies and regional communities. However, the lack of knowledge on pit lakes continues to hinder their proper management. Information on pit lake occurrence, distribution and water quantity and quality is not nationally collated and requires immediate and perpetual attention from both mining companies and regulating authorities. Lack of a readily available data-base pertaining to pit-lake occurrence, distribution and water quality fails to promote both mining companies and communities in RCF region in assessing the potential of these water resources.
Open pit mining creates a new type of aquatic habitat, which is formed by force flooding or natural filling of the pit when it is mined out. Pit lakes are generally narrow and deep, enclosed by steep rock walls and usually without a littoral zone. Their morphological features, with a marked meromitic (only partial circulations) character, restrict the hydro biological growth and the biodiversity in these habitats. Most of the technical papers related to the ecology of pit lakes deal with the formation of acidic environments [Klapper and Schultze (1995), Miller et al 1996, Levvy et al 1997, Geller et al 1998, Lessmann 2000, Packroff 2000, Kalin et al 2001, Boland and Padovan (2002)].
Water quality monitoring has one of the highest priorities in environmental protection policy. The main objective is to control and minimize the incidence of pollutant oriented problems, and to provide water of appropriate quality to serve various purposes such as drinking water supply, irrigation water. The quality of water is identified in terms of its physical chemical and biological parameters Boyacioglu(2006). Physicochemical characteristics of aquatic environment, viz. pH, specific conductance, total hardness, DO, BOD, nitrate nitrogen, phosphates etc. are the products of complex interactions among biotic, abiotic components of its water and soil and ambient climatic factors like temperature, humidity, wind, radiations intercepted with concomitant light, heat etc. The physico-chemical attributes of aquatic environment depend to a great extent on the activities of primary producers (micro- and macrophytes), consumers (micro- and macro fauna), decomposers (bacteria, fungi and actinomycetes) and their physical environment, which are likely to vary in the rhythm of seasonal variation of climate of the concerned place (Castro and Moore 1997).
In this context, for the first time the present study on status of pit lakes in Raniganj Coal Field was undertaken for conducting preliminary surveys. Specifically our objective was to make a database of pit lakes found in the RCF region through field interviews during the survey period. In this context, we also study some morphometric features of the pit lakes. Secondly, we carried out study on status of selected pit lakes water quality in Raniganj Coal Field.
CHAPTER 2: REVIEW OF LITERATURE
Lakes that develop in open cast mine voids are called mine pit lakes. The purpose of this review is to give a sound foundation of information regarding the pit lakes and existing limnological conditions in pit lakes at national and global level . Pit lakes differ physically from natural lakes in having markedly higher relative depths. (Castro and Moore, 2000). During active mining, surface water is diverted around open pits, and perimeter and/or in-pit dewatering pumps are used to control groundwater inflow and direct rainfall. Pit lakes form when the pumps are shut off and post mining drainage of surface/groundwater and precipitation begin to accumulate inside the inactive pit. Depending on the size and availability of suitable fill, backfilling open pits can be impractical and prohibitively expensive. In such cases, a pit lake forms and the mine operators are saddled with ensuring that it does not pose environmental and safety risks. (PinCock, 2006)
Based on climate, hydrologic conditions, and pit morphology, there are two basic types of pit lakes - terminal and flow-through. Terminal pit lakes are usually found in more arid climates where evapo-transpiration is greater than precipitation, and consequently water is not generally discharged from the pit lake. Due to evaporative processes, terminal pit lakes become cones of depressions in the water table with the groundwater gradient towards the pit (i.e., a groundwater discharge
zone). Since evaporation is the only discharge pathway, soluble metals accumulate and increase in concentration over time. (PinCock, 2006)
Flow-through pit lakes are usually found in climates where direct precipitation and water inflow exceed evapo transpiration. Consequently, the pits fill with water and discharge occurs - either via groundwater or surface water outflow. In this instance, and depending on the individual site conditions, the pit lake can serve as a ground water recharge area.
Open pit mining creates a new type of aquatic habitat, which is formed by force flooding or natural filling of the pit when it is mined out. Pit lakes are generally narrow and deep, enclosed by steep rock walls and usually without a littoral zone. Their morphological features, with a marked meromitic (only partial circulations) character, restrict the hydrobiological growth and the biodiversity in these habitats. Most of the technical papers related to the ecology of pit lakes deal with the formation of acidic environments (Klapper & Schultze, 1995; Miller et. al, 1996; Levy et. al., 1997; Geller et. al., 1998; Stevens & Lawrence, 1998; Packroff, 2000; Lessmann et. al., 2000; Kalin et. al., 2001; Boland & Padovan, 2002).
Freshwater is a finite resource, essential for agriculture, industry and even human existence. Without freshwater of adequate quantity and quality of sustainable development will not be possible. It is estimated that freshwater wetlands alone support 20 per cent of the known range of biodiversity in India. Hydrologic conditions can directly modify or change chemical and physical properties such as nutrient availability, degree of substrate anoxia, soil salinity, sediment properties and pH. These modifications of the physiochemical environment, in turn, have a direct impact on the biotic response in the wetland. A lake that has formed in a coal mining pit tends to be different from natural lakes. Natural lakes are usually shallower with a surface area to depth ratio less than 2%. In comparison, strip-pit lakes often have ratios approaching 40% (Miller et al 1996; Doyle and Runnells, 1997; Castro and Moore, 2000). This is important because the relation between depth and surface area is often the most important factor determining water circulation (Anderson et al 1985; Doyle and Runnells, 1997; Wetzel, 2001). Lakes that have smaller surface area to depth ratios are more likely to experience seasonal turnovers which keep the entire water column oxygenated. In contrast, a lake that is very deep relative to its diameter may become permanently stratified. This may result in a condition called meromixis in which an anoxic bottom layer of water called the monimolimnion becomes dense to the point that there is not enough energy in the system to mix this layer (Hutchinson, 1957; Doyle and Runnels, 1997; Wetzel, 2001).
Water quality of lakes generated at a former open pit mine present a wide variability, ranging from acidic, heavy metal-rich lakes (Berkeley pit, Montana), to near-neutral, low TDS ones (Cortez lake) (Miller et al., 1996). In general, chemical composition of a pit lake will depend on several factors that may change with time as it fills. Among these factors we highlight: 1) the chemical composition of the wall rocks, which is mainly related to the presence of iron sulfides at the pit walls and the environmentally hazardous consequences of their oxidation (heavy metal release and water acidification) and the possible existence of rock types with buffering capacity like carbonates or silicates; 2) the magnitude and geochemistry of the water sources flowing into the pit; 3) the precipitation/evaporation ratio; 4) the limnology of the future lake and its role in determining the transportation of chemical species through the water column; 5) the effect of biological activity (Miller et al., 1996; Castro et al., 2000; Davis, 2003).
Chapter 3: methodology
Study sites
The study was conducted from 2009 to2012 on pitlakes of the coal mining areas in Raniganj (Eastern Coalfield Limited) of Burdwan district of West Bengal. Area of entire Raniganj Coalfield Field (RCF) is about 1530 Sq Kms spreading over Burdwan, Birbhum, Bankura and Purulia Districts in West Bengal and Dhanbad District in Jharkhand. We selected the RCF pitlakes that covers the part of West Bengal on the basis of its size and utilization potential with a homogeneous geographical distribution under Eastern Coalfield Limited.
Inventory of Pitlakes
The survey of pit lakes was carried out in Raniganj Coal Field Area (Fig 1 a, b) from 2009 to 2012. We used structured questionary ( Zalidis 1996, MoEF 2008) aimed to collect various informations on RCF pitlakes. These include some basic informations on pitlakes viz common name, mine authority, mine area, nearest coal mine etc. For morphometric study we included the GPS location (latitude/longitude), elevation, length, width and surface area of the pitlakes. We used targeted people to collect these informations like Manager of the Coal Mine, ECL officials, local guards, local stake holders, self governments, common people etc. We also discuss some standard literature on RCF pit lakes.
Sampling of pit lake water
During the course of field study water samples were collected for analysis of selected physico-chemical parameters and nutrient conditions of 10 pit lakes[Table 1] of Raniganj Coal Field during March-April, July-August and November- December each year during 2009- 2012.
Analysis of water sample
The sensitive water parameter pH was analysed on the spot with the help of a portable pocket pH meter (pHep pH meter, Hanna instrument, Mauritius) respectively, at each site and each sampling day. Whereas samples for estimation of total hardness, calcium hardness, magnesium hardness, alkalinity, dissolved solid, sulphate, chloride and iron which allow time period of about 24-72 hours after collection, were brought to the laboratory for analysis following [APHA 2005]. Water was filled in 500 ml plastic bottle from each pitlake. From each sampling point three sets of collections were made and mixed to form a composite sample. The plastic bottles were washed with source water before filling them up.
Statistical analysis
XLSTAT version 2010 [Adinosoft, 2010] statistical package was used to analyze data obtained during this work. We applied multivariate statistics to get a glimpse on the present limnological condition of RCF Pit Lakes. We used Correlation Analysis (CoA), Principle Component Analysis (PCA) and Agglomerative Hierarchal Cluster (AHC) Analysis to predict the water quality prevailing in these Pit Lakes.
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Figure 1(a,b): Map of Raniganj Coal Field, West Bengal India
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Table 1: Distribution of study sites in Raniganj Coal Field (RCF), West Bengal, India for collecting water samples.
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- Quote paper
- Debnath Palit (Author), Debalina Kar (Author), Aparajita Mukherjee (Author), Santanu Gupta (Author), 2014, Pitlakes of Raniganj Coal Field, W.B, India. Inventory and Water Quality Status, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/270503
