Environmental impact assessment for the proposed project to upgrade the sewerage system Chaaya Island Dhonveli, Kaafu Atoll, Maldives

Abstract

This report discusses the findings of an environmental impact study under the proposed sewerage system upgrading project at Chaaya Island Dhonveli. The project is proposed by Tranquility Pvt. Ltd. The project entails upgrading the sewerage system to incorporate sewage treatment. The proposed system is similar to sewerage systems in other resorts. As such a comprehensive sewerage system with gravity flow pipes that convey the wastewater from buildings to several lift stations that pump the wastewater to the sewage treatment works for tertiary treatment of the influent. The treated effluent is proposed to be used for gardening/landscaping and toilet flushing. Upon recommendation from the EIA Consultants and the EPA (during the EIA Scoping Meeting), an emergency bypass has been included in the design with a pumping station that pumps the wastewater to a location beyond the reef at about 10-15m depth. Alternatives have been identified in the project document. Of these the recommended alternative involves minimizing the number of lift stations/pump stations and to maximize the use of gravity flow pipes to the greatest possible extent. Other alternative proposed include the no project option, which is the most practicable option in terms of economic as well as environmental impacts, however, this option is not feasible due to legal requirements that a sewage treatment plant has to be incorporated in the sewerage system of any tourist resort in the Maldives, as per Tourism Regulations. The main environmental concern in the project is the number of lift stations/pump stations in the revised design, which is too many for a small island. According to the project Engineers, it is difficult to get appropriate gradients without altering the existing sewer network. However, the EIA Consultants are of the opinion that the number of lift stations can be minimized and it has been recommended to minimize the number of lift stations/pump stations to the greatest possible extent. Environmental impacts were assessed for both the construction and operation phase of the project. Most of the environmental impacts identified for the proposed development were positive; these include reduced use of RO plant, reduced pollution of the groundwater and recycling of minerals such as nitrates, phosphates and sulphates. The main negative environmental impacts of the project would be temporary loss of groundwater quality during the construction phase due to dewatering and small amount of sedimentation induced from installing the emergency outfall. The latter could be regarded as insignificant due to its small magnitude and spatial constriction. The proponent is willing to undertake monitoring during and after the construction phase in addition to undertaking the mitigation measures proposed by the consultants. The main mitigation measures for this project during the construction phase is similar to other construction projects such as dust control plans, working during low- tide as much as possible and avoiding operation of loud machineries during late hours. As for the operation phase, implementation of backup systems and trained maintenance staff to service the STP and reducing the production of fatty and oily waste from the resort has been proposed. In conclusion, it appears justified from a technical, administrative and to some extent environmental point of view, to carry out the proposed project to upgrade the existing sewerage system to incorporate a treatment plant into the existing sewerage network. However, there are alternative that may be more suitable and shall be considered with caution and after understanding the costs and discussions with relevant government authorities.