Arsenic Aquifer Sealing Technology in Wells: A Sustainable Mitigation Option
The act of constructing unprotected/unsealed wells to extract water from deep aquifers is a worrisome ongoing practice in most parts of developing countries of the globe. The paper is first of its kind in exploring sealing technology as a potential mitigation measure to prevent arsenic contamination of deep aquifers. The technology has been assessed not only as a safeguard to potential microbiological or mineralogical contamination of aquifers but also as an adaptive option in case of climate-induced disasters like drought or flood where it can serve as emergency safe drinking water source. This paper puts forward comparative findings of mini-arsenic blanket testing of 358 wells (unsealed) performed at an interval of 8 years in Nawalparasi, district of Nepal, along with the performance monitoring of eight different sealed wells ranging from 20 to 80 m deep for over a period of 7 years. The paper focuses on the construction methodology and performance evaluation of four sealed shallow wells constructed in the same district. Mini-arsenic blanket test results show 38, 37, and 25 % of bore wells with respective increasing, decreasing, and constant level of arsenic concentrations whereas the sealed wells exhibit steadiness in arsenic concentration range of particular tapped aquifers within Nepal drinking water quality standard for arsenic of 50 μg/l over a long period, even though the tapped aquifers lie intercepted in between adjacent arsenic elevated aquifers. Sealed shallow wells exhibit good aquifer seal characteristics beyond potential resultant existing positive difference to cause downward aquifer cross-contamination. The presented technology can be used and replicated in deep/multi-aquifer hydrogeology of Nepal and South Asia for extraction of water from deep and safer aquifers in rural and urban water supply systems by escaping overlying arsenic-contaminated aquifers.
KeywordsArsenic Aquifer contamination Sealing technology
- ASTM. (2010). D 5092- 04(2010)e1.Standard practice for design and installation of groundwater monitoring well. West Conshohocken, PA, 19428–2959 USA, American Society for Testing and Materials (ASTM).Google Scholar
- CBS. (2011). Nepal—National Population & Housing Census 2011. Kathmandu, Nepal Central Bureau of Statistics (CBS), National Planning Commission Secretariat, Government of Nepal.Google Scholar
- Danert, K., Luutu, A., et al. (2010). Costing and pricing—a guide for water well drilling enterprises : RWSN Field Note 2010–6 (Cost Effective Boreholes Series). St Gallen, Switzerland, RWSN.Google Scholar
- DENR. (2003). Standard operating procedure-three: monitoring well design and installation. South Dhaka, Department of Environment and Natural Resources (DENR), Government of Bangladesh: 14.Google Scholar
- Jolliffe, I. (2005). Principal component analysis. Wiley Online Library.Google Scholar
- Lawoti, S. S. (2006). Diluting the pain of arsenic poisoning in Nepal. From http://www.unicef.org/wash/nepal_35975.html.
- Maharjan, M. (2012). Community involvement of sustainable arsenic safe drinking water in lowland. Kathmandu: Environment and Public Health Organization (ENPHO).Google Scholar
- Maharjan, M., Shrestha, R. R., et al. (2011). Prevalence of arsenicosis in Terai, Nepal. Journal of Health, Population and Nutrition (JHPN), 24(2), 246–252.Google Scholar
- NAISU. (2003). Arsenic 2002—an overview of arsenic mitigation initiatives in Bangladesh NGOs Arsenic Information & Support Unit (NAISU) and NGO forum for drinking water supply & sanitation: 125.Google Scholar
- NASC. (2007). Report on blanket tube well testing in Sunsari, Bara, Dhanusha, Rupandehi, Kailali & Kanchanpur district, Nepal, National Arsenic Steering Committee (NASC), Nepal.Google Scholar
- NASC. (2011). The State of Arsenic in Nepal, National Arsenic Steering Committee (NASC), Department of Water Supply and Sewerage, Ministry of Physical Planning and Works, Government of Nepal.Google Scholar
- Ravenscroft, P. (2007). Predicting the global distribution of arsenic pollution in groundwater. Royal Geographical Society Annual International Conference, Department of Geography, Cambridge University.Google Scholar
- Thakur, J. K., Singh, P., et al. (2013). Geochemical modelling of fluoride concentration in hard rock terrain of Madhya Pradesh, India. Acta Geologica Sinica - English Edition, 87(5), 1421–1433.Google Scholar
- WECS. (2011). Water resources of Nepal in the context of climate change 2011. Singha Durbar, Kathmandu, Nepal, Water and Energy Commission Secretariat (WECS), Government of Nepal: 89.Google Scholar
- WHO. (2000). Global water supply and sanitation assessment (p. 87). Geneva: World Health Organization (WHO).Google Scholar
- World Bank, T. (2005). Arsenic contamination of groundwater in South and East Asian Countries. Volume II Technical Report, The World Bank, Environmental and Social Unit - South Asia Region and Water and Sanitation Progam (WSP), South and East Asia. II.Google Scholar
- World Bank, T. (2014). World development indicators. Retrieved 13 Jan 2014, from http://databank.worldbank.org/data/views/reports/tableview.aspx.
- WSSD. (2011). Water supply, sanitation and hygiene: sector status report Water Supply & Sanitation Division (WSSD), Ministry of Physical Planning and Works, Government of Nepal.Google Scholar