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 JWARP  Vol.10 No.1 , January 2018
Recycling Tailings Seepage Water for Diogo Heavy Minerals Mine Sustainability (Northern Senegal)
Abstract:
The sandy Quaternary and the deep Maastrichtian aquifers located in the northern coastal zone of Senegal, from the locality of Kayar in the south to Saint-Louis in the north, constitute the main sources of water supply for urban and local needs as well as mining activities. The Quaternary aquifer that provides the water required for the irrigation of local farmlands, hosts a significant heavy mineral sands deposit currently being mined by the Grande Cote Operations (GCO). As a result of variable rainfall and increased water abstraction, this shallow aquifer has recorded a continuous water level decline since 1970, with potential negative effects on both the social and economic development of the region. The mining of heavy minerals (zircon, ilmenite, leucoxene and rutile) at GCO is realised through conventional dredging techniques that require large volumes of water (up to 60,000 m3/d). The water pumped by the dredge to enable the extraction of the heavy minerals, infiltrates into the shallow aquifer, runs-off into the dredge pond or evaporates. The objective of this study is to evaluate a water balance that enables the provision of a permanent water supply to the dredge pond, whilst minimising the risk of flooding of the cropping depressions adjacent to the mine site or drying out of the farming wells. The hydrodynamic model implemented for this purpose was calibrated and tested during the first year of operation. The Root Mean Squared Error (RMSE) obtained for the calibration is approximately 0.52 m. The predictions indicate a requirement for the system to recover part of the tailings infiltration through dewatering boreholes. The quantity of recycled water is estimated at 16,000 m3/d on average. The model simulations show an additional water requirement, extracted from the deep Maastrichtian aquifer, varying between 23,000 and 28,000 m3/d to achieve the optimum pond water level.
Cite this paper: Seck, M. , Faye, S. , Robertson, M. and Rose, M. (2018) Recycling Tailings Seepage Water for Diogo Heavy Minerals Mine Sustainability (Northern Senegal). Journal of Water Resource and Protection, 10, 121-144. doi: 10.4236/jwarp.2018.101008.
References

[1]   Sane, M. (2015) Notes sur les Ressources en euax du Senegal: Zones potentielles pour le transfert d’eau. Ministere de l’Hydraulique du Senegal, Dakar.

[2]   ISRA (1996) Rapport Annuel. DAKAR.

[3]   Dryade (1990) Inventaire Biophysique de la région des Niayes Synthèse, document de recherche dans le cadre du Project Conservation des Terroirs du Littoral, Ministère du Développement Rural et de l’Hydraulique, DFCCS. Republique du Senegal, Dakar, 262 p.

[4]   TROPICA (2005) Etude d’impact environnemental et social (EIES) du Projet Zircon de la Grande Cote. 92-93.

[5]   Faye, S., Diaw, M., Ndoye, S., Malou, R. and Faye, A. (2009) Impact of Climate Change on Groundwater Recharge and Salinisation of Groundwater Resources in Senegal. Groundwater and Climate in Africa, Kampala, June 2008, 163-173.

[6]   Kane, A. (1985) Le bassin du Sénégal à l’embouchure Flux continentaux dissous et particuliaires. Invasion marine dans les vallées du Fleuve. Thèse doct, 3ème cycle, Trav. Lab. geogr. Phy. Univ. de Nancy II, Dakar, 186 p.

[7]   Michel, P. (1973) Les bassins des fleuves Sénégal et Gambie. Etude géomorphologique. Mém. ORSTOM. N63, 3 tomes, Paris, 752 p.

[8]   Michel, P. (1956) Rapport préliminaire sur la géologie de la région des Niayes, de Kayar à l’embouchure du Sénégal. Rapport inédit MAS.

[9]   Puttalaz, J. (1962) Hydrogéologie de la région des Niayes. Rapport DAK 62-A12, 37 p.

[10]   Noel, Y. (1978) Etude hydrogéologie des calcaires lutétiens entre Bambey et Louga (2ème phase). BRGM, Orleans, 100 p.

[11]   Kaba, M., et al. (2016) Spatial and Seasonal Variability of Groundwater Hydrochemistry in the Senegal North Littoral Aquifer using Multivariate Approach. Environment Earth Sciences, 75, 274.
https://doi.org/10.1007/s12665-016-5520-x

[12]   MDL (2010) Grande Cote Operations—Definitive Feasability Study: Engineering and Technical. GCO, Senegal.

[13]   Herchenchorn, W., et al. (2006) From Heavy Minerals Mining to a Wet Dredge Mining Operations. In: Proceedings of the World Dredging Congress, Papers and Presentations, TIB Leibniz Information Centre for Science and Technology, 1, 129-140.

[14]   Consolidated Rutile Limited (CRL) (2010) How Are Mineral Sands Mined on North Stradbroke Island?

[15]   Associates, G. (2007) Snapper Mineral Sands Project Environmental Assessment-Hydrogeological Assessment. Bemax Resources Limited, Mildura.

[16]   De Marsily, G. (1986) Quantitative Hydrogeology. Academic Press, Paris.

[17]   Mondal, N.C., Singh, V.P. and Sankaran, S. (2011) Goundwater Flow Model for a Tannery Belt in Southern India. Journal of Water Resource and Protection, 3, 85-97.

[18]   Diersch, H.-J.G. (2005) FEFLOW Software—Finite Element Subsurface Flow and Transport Simulation System—Reference Manual. WASY GmbH, Berlin.

[19]   Grzina, A., et al. (2002) Slurry Pumping Manual. A Technical Application Guide for Users of Centrifugal Slurry Pumping Systems. Warman International Ltd.

[20]   Robertson, M. (2013) Groundwater Assessment. Path 1-4 Tailings and Water Management. Grande. Grande Cote Operations (GCO).

[21]   Faye, S. (1995) Modélisation hydrodynamique des nappes du littoral nord entre Cayar et St-Louis. Impact des futurs prelevements envisages dnas le cadre de l’approvisionnement en eau de Dakar et de ses environs. These de 3e cycle, UCAD, Dakar, 167 p.

[22]   Berehanu, B., Ayenew, T. and Azagegn, T. (2017) Challenges of Grundwater Flow Model Calibration using Modflow in Ethiopia: With Particular Emphasis to the Upper Awash River Basin. Journal of Geoscience and Environmenent Protection, 5, 50-66.
https://doi.org/10.4236/gep.2017.53005

[23]   Lalot, E. (2014) Analyse des signaux piezometriques et modelisation pour l’evaluation quantitative et la caracterisation des echanges hydrauliques entre les aquiferes alluviaux et rivieres—Cas du Rhone. Ecole Nat. Superieure des Mines de Saint Etienne.

[24]   Shahid, S., Alamgir, M., Wang, X.-J. and Eslamian, S. (2017) Climate Change Impacts on and Adaptation to Groundwater. Researchgate, 107-123.
https://doi.org/10.1201/9781315226781-7

[25]   GKW Consult (2009) Modélisation numérique—Littoral Nord, Rapport Phase IV. Lot 1B. Projet Eau à Long Terme, Republique du Senegal, Senegal.

 
 
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