GROUNDWATER MONITORING IN THE CONTEXT OF ARSENIC MITIGATION IN BANGLADESH: SITE SELECTION AND IMPLEMENTATION STRATEGIES

Groundwater arsenic contamination is a major challenge in increasing safe water coverage in Bangladesh. More than 17 million people in Bangladesh are still exposed to arsenic concentration in drinking water exceeding the Bangladesh drinking water standard of 50 µg/l. Groundwater arsenic contamination is not uniform and has various scale of spatial heterogeneity. Besides, it is not yet well understood whether an arsenic safe section of an aquifer will remain arsenic safe in the long run or not. Therefore, a comprehensive groundwater monitoring network with a central protocol for quality-ensured data capturing would ensure and lay the foundation for efficient data management and groundwater analysis to develop the systematic capacity building of the groundwater resources in Bangladesh. The Department of Public Health Engineering (DPHE), the government agency tasked with ensuring the provision of safe drinking water, is currently constructing monitoring wells to understand variations in groundwater level and water quality. This study provides a structure for prioritization, siting and planning for installation of monitoring wells. It is identified that the land ownership, preferably a union headquarter (the lowest administrative entity), participation of the local government institutions, modification of the current institutional framework of the Department of Public Health Engineering, capacity building of the local drillers for selection of the appropriate depth (preferably shallow, intermediate and deep aquifers) and layer for monitoring, as well as a centralized system for storing and analysis of monitoring data are the key requirements for a sustainable monitoring system. We also provide general instruction for the drilling, sampling, construction, instrumentation, and data collection strategy and protocols for the monitoring well installation. A digital platform - ASMITAS has been developed for digital data acquisition from the piezometers as well for supporting decision making by different actors working in the water supply sector. Monitoring well installation following this strategy may help to target arsenic-safe aquifers and provide information on local geological settings, groundwater level fluctuation and groundwater chemistry at strategic locations that can be used for successful installation of arsenic safe wells.