Development of a technical concept of spatial and temporal coordinated mine water recycling exempli ed by a mining area with urban in uence
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Development of a technical concept of spatial
and temporal coordinated mine water recycling
exemplified by a mining area with urban influence
Antje Ulbricht1, Felix Bilek1, Katrin Brömme2
1
Groundwater Research Centre Dresden, Meraner Str. 10, 01217 Dresden, Germany, aulbricht@dgfz.de
2
Ruhr University Bochum, EE+E Environmental Engineering and Ecology, Universitätsstraße 150,
44780 Bochum, Germany, katrin.broemme@rub.de
Abstract
A technical concept for an integrated mine water management regarding the spatial and
temporal change and the strong seasonal weather variations was developed. The aim of
the concept is the modification of the water infrastructure within the project area Hon
Gai peninsula, Ha Long, Vietnam, to balance temporal water deficits. The adaption of the
water treatment to the individual requirements of various users is also included in the
concept. The methods and tools to identify the need for action and assess possible solu-
tions are described.
Keywords: integrated water management, technical concept, mine water use, post-min-
ing land use planning, Vietnam
Introduction manganese concentrations. Currently, this
One of the hardcoal mining areas in Quang water is treated partly and reused for purpos-
Ninh, Vietnam, is located on the Hon Gai es like coal screening, truck wash, domestic
peninsula next to Ha Long City. The mine wa- use and watering plants. Due to the closing
ter affects the surface water on the peninsula of open pit mines the process water volume
and the coastal water of Ha Long Bay, which will decrease in the future. Consequently
was recognized as World Natural Heritage the amount of water which can be reused
Site by UNESCO in 1994. For this region a for these purposes will decrease. The surface
concept for an integrated mine water man- runoff contains high loads of sediment and
agement will be developed by the WaterMin- coal dust. After heavy rain events the water
er project, which is sponsored by the German and the sediments are transported by rivers to
Federal Ministry of Education and Research the urban area where the sediment and coal
(BMBF). Due to spatial changes and the pre- dust deposit. The amount of this water and
dictable change of the water demand caused the containing substances are currently not
by closure of mining and the socio-economic treated or reused.
development, the concept includes the cur- Due to socio-economic changes of the
rent stage as well as future stages of devel- region the water demand for domestic pur-
opment of the region. The project combines poses will increase. Thus one of the major fu-
the analysis from a material flow perspective ture challenges of this region is to cover the
(Brömme et al. 2018) and from an economic increasing water demand. The temporal fluc-
perspective (Do et al. 2018) with the technical tuating water quantity with water scarcity in
perspective which is presented here. The final dry season and flooding events in the rainy
product is a spatial and temporal coordinated season is a major difficulty for the water man-
mine water management. agement.
On the Hon Gai peninsula the mine wa- A technical concept is established which
ter origins from the draining of the mines includes solutions to support the water infra-
(pit water) and the surface runoff within the structure and balance water deficits and ex-
mining area. The pit water is characterised cess supply to guarantee a constant and long-
by moderate concentrations of iron and high term water supply for the whole region. The
210 Wolkersdorfer, Ch.; Sartz, L.; Weber, A.; Burgess, J.; Tremblay, G. (Editors)
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11th ICARD | IMWA | MWD Conference – “Risk to Opportunity”
aim is to store, treat and supply surplus water water gauges, will be used. The water levels at
to various users in the area according to their various cross sections are required to calcu-
individual quality and quantity requirements. late the water discharges. The knowledge of
the discharge amount is the basis of the de-
Data acquisition termination of the surface runoff within the
From 2005 to 2015 morphologic data, cli- mining area and the calibration of the precip-
matic data and data about the water qual- itation-runoff model.
ity of the project area were collected with-
in RAME project (EE+E Environmental Methods
Engineering+Ecology 2016). These data Due to the declining mining activities, the
were expanded and revised by the integra- corresponding landscape transformation
tion of new data which was collected during and the change of the water demand and
fieldtrips. Interviews with staff and managers water sources, the technical concept in-
of the mining companies and VINACOMIN cludes three stages of the project area. Stage
(Vietnam National Coal – Mineral Industries 1 is the current stage with both open pit and
Holding Corporation Limited) resulted in underground mining. Stage 2 represents the
new information regarding the future territo- near future when the opencast operations
ry planning. On the basis of this information and partly underground operations will be
the existing digital elevation models were up- stopped. Stage 3 describes the final situation
dated (fig. 1) to get information about future of the area when the recultivation and land-
morphology, catchment area borders and scaping is finished. For these stages the data
possible water storage volumes. was collected to identify the main difficulties
The geometry of the rivers (cross sections, of the water and sediment management and
slopes) was surveyed and water qualities find solution approaches (tab. 1). Possible
were determined by taking water samples. measures to improve the water quality and
The sediment samples were taken within the water management will be examined with the
mining area and along the riverbanks to ob- help of modeling tools (fig. 2).
tain knowledge of the sediment composition The major uncertainty of the currently
(grain sizes, share of coal dust). available data is the quantity of surface runoff
Data about hydrological conditions of and the sediment which is transported from
the rivers are currently not available. Due the mining area into the rivers. The discharge
to this fact a monitoring concept was cre- data is necessary for planning technical mea-
ated to observe the river water levels and to sures to improve the water treatment and the
measure the quality parameters pH, electrical water distribution system. It is also needed to
conductivity, temperature and turbidity. For estimate the effectiveness of future water stor-
the monitoring multiparameter probes and ages. Information about the eroded sediment
cameras, which observe the water levels at and coal dust will be used to plan the recov-
Figure 1 spatial change of the Ha Tu mining area (left: current stage, right: final stage)
Wolkersdorfer, Ch.; Sartz, L.; Weber, A.; Burgess, J.; Tremblay, G. (Editors) 211
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ery and separation of this material. To obtain tween water and the geological structures
these information the surface water runoff is indispensable. The model ModelMuse
and the sediment transport will be calculated (MODFLOW) will be used to simulate
with the precipitation-runoff model HEC- groundwater and lake water levels depend-
RAS. The developed monitoring system will ing on the climatic conditions and different
provide data to calibrate the model. mining stages to identify the quantity of these
To determine the quantity of usable water storages. The influence of withdrawal rates
in storages like lakes or aquifers the knowl- will be analysed. Possible positions of wells
edge of water levels and the interactions be- and treatment plants will be planned.
objective
• modeling of the arising water and • modeling of lake water and groundwater
sediment loads levels to determine storage volumes
• planning of measures for sediment • change of the groundwater level depending
retention on different water withdrawal rates
input and calibration data monitoring system
• elevation models of the terrain surface • Hydrological data
for different mining states • geological data
• climatic conditions • hydraulic parameters of the dump material
• river geometry/water management • soil parameters, sediment composition
infrastructure (dams/basins) • water sources/water withdrawals
precipitation-runoff and sediment groundwater model
transport model
(ModelMuse/MODFLOW)
(HEC-RAS)
output output
• water level and discharge of rivers • groundwater level, lake water level
• sediment transfer, sediment • storage volumes
deposition, areas of deposition • possible withdrawal rates
• sediment composition (grain size) • possible land use
• required capacity of storage basins • locations of wells and water
treatment plants
Figure 2 modeling tools and data requirements for system analysis and the assessment of technical measures
212 Wolkersdorfer, Ch.; Sartz, L.; Weber, A.; Burgess, J.; Tremblay, G. (Editors)
02_Water treatment process BOOK.indb 212 9/3/18 12:13 PM11th ICARD | IMWA | MWD Conference – “Risk to Opportunity”
Results and Discussion In the future the greatest difficulty will be
Several difficulties for the water management the water deficit in dry season (tab. 1). On
occur due to the high climatic seasonality, the the annual average there is enough water to
socio-economic development of the region cover the increasing water demand. Conse-
and the change of landscapes caused by the quently, storage possibilities are identified to
closing and restructuring of the mining areas guarantee the water supply in dry season.
(tab. 1). Currently, the greatest difficulty is the When the coal dust and sediment loads
poor water quality in rainy season caused by will decrease due to the restructuring or the
the high sediment loads. To prevent the sedi- closing of open pit mines the settling basins
ment deposition in the urban area and to re- will not be necessary anymore. Then the ba-
tain the sediment within the mining area the sins can be used as storage basins for water.
technical concept includes the restructuring Furthermore, a concept for the final stage was
of the rivers and the installation of settling developed which includes the re-utilisation
basins. Within the WaterMiner project those of the already existing pits and dumps as wa-
measures will be planned exemplary for a ter storages (fig. 3). The water of the pit lakes
section of the Lo Phong River in the Ha Tu and the groundwater which is accumulated
mining area. Depending on the needs of the in the porous material of the dumps can be
Vietnamese partners the coal sludge and the used for several purposes. Depending on the
clastic sediment can be either recovered and quality requirements of the future water us-
separated for later reuse or simply dumped ers the treatment process and the distribution
together. system have to be adapted.
Table 1. Difficulties and solution approaches depending on different mining stages
stage 1 – stage 2 – stage 3 –
current stage near future final situation
difficulties high water discharges with increasing water deficit in the large water deficit in the urban
high sediment loads, sediment urban area (dry season) area (dry season)
deposition along the river (rainy retention of floods is necessary retention of floods is necessary
season) (rainy season) (rainy season)
solutions installation of settling basins former settling basins can be use of the water of pit lakes,
to retain sediment load, used as retention basins, use of use of dumps as groundwater
restructuring of the river closed open pits as reservoir storage, adaptation of the water
infrastructure and the water
treatment
water sources water from open pit and water from underground precipitation
underground mining, mining, precipitation
precipitation
treated water base flow, water from open pit base flow, water from lake water, ground water
and underground mining underground mining, water
which is stored in open pits and
basins
water use truck wash, coal screening, agriculture, industry, domestic domestic use (city), agriculture,
watering plants, domestic use use (mining companies) industry
(mine internal)
possibilities to store settling basins, open pits Lake, settling basins, aquifer
water
sediment retention Settling basins, separation of (vegetation of dump sites)
coal sludge
Wolkersdorfer, Ch.; Sartz, L.; Weber, A.; Burgess, J.; Tremblay, G. (Editors) 213
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forest (drinking
catchment bank filtrate water protection
zone)
well gallery
dump dump
future lake
groundwater - storage
N S
cross section
MWTP
catchment water works
lake water body of groundwater treatment distribution
storage, storage, filtration, aeration, deironing,
sedimentation of suspended degradation of demanganisation,
solids, organic matter adjustment of lime-carbonic
iron oxidation acid equilibrium, desinfection
agricultural use
Figure 3 concept for the use of pit lakes and adjoining aquifers as water sources and storages and necessary
treatment steps for several purposes
The developed technical concept is suit- Acknowledgements
able for the water management of regions The project is sponsored by the German
with open pit mining in areas characterised Federal Ministry of Education and Research
by strong seasonality of precipitation. In min- (Fkz. 02WAV1410A). The authors thank all
ing areas with underground mining problems contributors of the project partners Ruhr
like the salinization of groundwater occur, University of Bochum - EE+E Environmen-
thus the water can not be used or has to be tal Engineering and Ecology, VINACOMIN
treated by cost-intensive technologies. In Vietnam National Coal – Mineral Industries
such cases a well-connected regional water Holding Corporation Limited, ribeka GmbH,
distribution system and appropriate artificial disy Informationssysteme GmbH, LUG En-
water reservoirs are the basis for the preven- gineering GmbH and University of Koblenz-
tion of local water deficits. Landau - Environmental Economy.
Conclusions References
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ment and groundwater models will be used Vietnam. Proceedings of the International Mine
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resources which can be recovered. The con- 2018. Pretoria, S_Africa (in publication).
cept will support the adaption of the water
Brömme, K., Trinh, V.Q., Greassidis, S., Stolpe, H.
infrastructure to the future development and
(2018) Material flow analysis for spatiotemporal
the increasing demands of residents, tourists
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Association Congress IMWA, 10-14 Sept. 2018.
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214 Wolkersdorfer, Ch.; Sartz, L.; Weber, A.; Burgess, J.; Tremblay, G. (Editors)
02_Water treatment process BOOK.indb 214 9/3/18 12:13 PMYou can also read
