Environmental impact assessment : for the proposed development of sewerage system Funadhoo, Shaviyani Atoll, Maldives : tsunami reconstruction project

Abstract

This report discusses the findings of a social and environmental impact study undertaken by Oriental Consultants and Yachiyo Engineering of Japan at the request of the Ministry of Environment, Energy and Water. Although this is a rehabilitation project, the sewage disposal system in Funadhoo needs more than rehabilitation but a completely new system. Therefore, in accordance with the requirements of the EIA Regulation, an EIA is necessary for the proposed project. The project involves the decommissioning of the existing system and development of a new sewerage system in Funadhoo. This project is initiated by the government of Maldives with funding from Japan Bank for International Cooperation (JBIC) as part of the tsunami rehabilitation programme. The existing sewerage system of Funadhoo was built by the people on a need basis by individuals constructing septic tank and pit disposal system within their house plots. There are also a few connecting their septic tank systems to gravity flow sewer pipes disposing to the lagoon. The system is not so functionable and has some environmental problems, which need to be addressed. The environment of Funadhoo may be described as well managed, with few environmental problems with appropriate solid waste management, few sewer lines with nearshore outfalls, clear lagoon which is in near pristine state in most areas except for the threat of pollution due to increasing signs of pollution from nearshore disposal of sewage using multiple outfalls, good housing with apropriate ventilation, sound level of urban planning, presence of beach and recreational areas. However, faecal contamination and subsequent smell in groundwater is one of the main environmental problems the island has to deal with immediately. Stakeholder consultations were held with various groups, including the community and the client in order to incorporate the socio‐economic components in the project. People are keen to establish a proper sewerage network disposing sewage appropriately with minimal environmental impact. There are social concerns regarding septic tanks including lack of space for such facilities, which the community would like to abandon, if possible. 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 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 improved sewerage system. There are other minor negative impacts such as small amount of excavation to lay the outfall pipe and dewatering to lay the sewer network in some areas including dewatering for the construction of manholes, lift stations and sumpwell at the STP and outfall. 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, including secondary treatment before discharging final effluent to sea, removal of existing sewers and outfalls and improvements to lagoon and coastal conditions in order to attain the benefits of the project. It was observed from current measurements and wind data based modelling that the location chosen for sewage treatment plan and outfall is appropriate and would not require treatment considering the small size of the population. However, treatment has been incorporated. The main mitigation measure would be water conservation and measures to minimize drawdown on the aquifer, especially introducing the skimming well technology through awareness creation. This is considered necessary whatever the sewerage system, if it uses groundwater for flushing. The proposed design for Funadhoo sewerage system has been prepared after considering all impacts, discussions with community and consideration of mitigation measures. 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. Therefore, a monitoring component has been suggested which takes in to consideration, the most important elements that require regular checks. This monitoring component will be adhered to and will allow the assessment of changes due to construction and implementation of the proposed sewerage system. Monitoring is specifically focussed on ground and surface water quality changes. Reef monitoring is considered inappropriate given that there will be sewage treatment and the housereef at the given location would not be affected due to currents in the area. In conclusion, it appears justified from a technical and environmental point of view, to carry out the proposed project to improve sanitation in Funadhoo.