Environmental impact assessment for the proposed development of sewerage system: Naifaru, Lhaviyani Atoll, Maldives

Abstract

This report discusses the findings of a social and environmental impact assessment (EIA) study undertaken for the development of a comprehensive sewerage system in Naifaru in Lhaviyani Atoll. This EIA is the culmination of a three-step environmental management process that involves mitigation and monitoring as an integral part. Mitigation measures and monitoring programme has been outlined and a summary Environmental Management Plan has been given in this EIA report. This project is initiated by the government of Maldives with funding from Asian Development Bank (ADB) as part of the technical assistance loan under the Second Phase of the Regional Development Project. At this stage, there is no funding for the project implementation but the design and EIA only. Naifaru, being the fifth most populated island and the third most densely populated island in the country before the reclamation is in need of an upgrade of its sewerage system. Overall, there are other environmental problems such as solid waste management and water supply and the overall environmental management of the island is poor owing to congestion and other reasons. Community consultations revealed that the most urgently required environmental improvement is a comprehensive sewerage system that cuts down the number of outfalls and does not pollute the island environment. Naifaru has a gravity flow sewerage system with small catchpits and with 24 outfalls disposing into the beach or lagoon. The system is old and has been continuously contaminating the beach and lagoon environment with sewage and wastewater. Environmental impacts were assessed for both the construction and operation phase of the project. Most of the environmental impacts of the project have been identified as positive resulting mainly from improvements to groundwater and lagoon water quality and resulting reduction in water-borne and water-related diseases and general ill-health. The main negative impact of the project would be that of excessive drawdown on the aquifer resulting from the flushing needs of the improved sewerage system. There are other minor negative impacts such as small amount of excavation to lay the sewer network in some areas including dewatering for the construction of manholes, lift stations and sumpwell at the pumping station. These impacts are considered to be moderate but short-term. The socio-economic benefits of the project may be considered to outweigh the negative impacts of the project. Mitigation measures for anticipated negative impacts have been identified and outlined in detail, including minimizing dewatering, laying the sewers properly including the outfall, locating the outfall at adequate depth, removal of existing sewers and outfalls and improvements to lagoon and coastal conditions in order to attain the benefits of the project. The main mitigation measure would be water conservation and measures to minimize drawdown on the aquifer. Skimming wells that draw water from close to the water table has been suggested as an important mitigation measure. These measures require community awareness, involvement and participation from the planning stages and even during the operational phase. Social benefits of the project will be enhanced if community consultation and participation mechanisms are strengthened including the development and implementation of Grievance Redress Mechanisms, which simply involve letting people the access to express their grievance with assured confidentiality. This will help to improve project performance. It is inevitable that there would be some negative environmental impacts. However, these are minor compared to the positive effects of the proposed system. Yet, monitoring to ensure the effectiveness of the proposed system would be necessary in order to evaluate the actual performance of the proposed system and to ensure future systems are remedied of design faults in the present and proposed systems. Therefore, a monitoring component has been suggested. Monitoring is specifically focussed on ground and marine water quality changes. Groundwater monitoring is essential for ensuring that the effects of dewatering to lay the pipes is minimized during the construction phase and to measure the level and speed at which salinisation of the groundwater occurs as a result of groundwater use for toilet flushing during the operational phase. Reef monitoring is considered inappropriate given the scale of anthropogenic damage to the reefs of Naifaru including the impacts of the dredging and reclamation that was recently undertaken, the effects of which have not been monitored. Therefore, an island-wide environmental monitoring programme is suggested. However, proposed marine water quality monitoring will help establish the long term environmental performance of the proposed sewerage system. In conclusion, it appears justified from a technical, social, economic and environmental point of view, to carry out the proposed project to improve sanitation in Naifaru.