Abstract: | This report discusses the findings of an environmental impact study undertaken by Water
Solutions Pvt. Ltd in order to fulfil obligatory requirements of the National Environment
Protection and Preservation Act, Law No. 4/93 for the proposed setup of the sewerage system
(hereafter referred to as the project) in Omadhoo island, Alifu Dhaalu Atoll, Maldives.
The purpose of this EIA is to identify and minimize potential adverse environmental
impacts related to this project and enhance the overall quality of the project. By examining the
project location, the legal framework and the existing environmental components such as
marine ecology and the socio-economic aspects, this EIA provides useful information regarding
the extent, nature and the magnitude of impacts that are likely to occur. The EIA will also help
to identify the long term socio-economic benefits to the community after implementing this
project. It also provides a framework for future monitoring of the environment, so that changes
can be monitored and corrective measures can be undertaken.
The proposed project aims to establish a sewerage collection and disposal system in the
island of Omadhoo in Alifu Dhaalu Atoll. The concept designed for Omadhoo is a gravity type
wastewater collection and disposal system. The existing systems are mainly based on septic
tanks and small bore sewers. Without proper maintenance these systems are prone to damage
and contamination of groundwater can occur. The contamination of the groundwater has
occurred to the extent that it cannot be utilized for any potable use. Therefore, the current setup
is not environmentally acceptable nor suitable.
The sewerage system for ADh. Omadhoo will be a gravity sewerage system where
sloping pipelines will allow waste water from the entire island to flow to two zonal pumping
stations. The sewage will be pumped from the pumping station to the treatment plant where it
will be treated and discharged via a sea outfall pipeline into the sea. The sewerage system will
comprise of elements of a given specification for sewer mains, cleanouts, manholes, vents,
pump stations, outfall pipeline and diffuser that will ensure a 30 year design flow.
The sewerage system therefore comprises of the following components:
a) Household inspection chambers.
b) A gravity sewerage reticulation network.
c) Reticulation pumping stations and pressure main system.
d) Construction of a sea outfall to discharge the sewage into deep sea.
The proposed project will ensure that the groundwater of the island does not get
contaminated through improper sanitation systems. It will also ensure that the surrounding
marine environment will improve in terms of environmental quality and will ensure pollution
from sewage does not occur on the near shore environments.
The project is expected to bring several positive impacts on the environmental quality of
the island and the surrounding reef. Particularly, the most significant benefit would be achieved
through improvement in the bacteriological quality of the groundwater. The health benefits of
the project are worthy of noting as the improvement in water quality are going to bring
significant health benefits to the community. Environmental & social impacts and the mitigation measures
Several environmental impacts of this proposed project have been examined through a
number of processes. These include consultations with the project development team, field
surveys, observations and assessment, and field experience gained from similar development
projects implemented throughout the country. Potential positive and negative impacts on the
environment have been considered. The assessment indicates environmental impacts, both
during the construction and operation stage. During the construction period, impacts are likely
to occur on the marine and terrestrial environment (groundwater).
Most of the impacts during the construction period are impacts related to construction
waste, dewatering, disruptions to the local traffic, dust emission, damage to the reef during sea
outfall construction and noise. During the operational stage of this project, there will be both
positive and negative impacts. Positive impacts include the improvement of the ground water
quality of the island. Negative impacts include the increased in extraction of groundwater for
toilet flushing that may increase the chances of groundwater salinization at a much accelerated
rate. This project does foresee some negative impacts even during the construction stage but is
geared towards improving the overall environmental quality of the island, most notably the
environmental health.
The project is presently planned to lay the sewer pipeline along the centre of the exiting
road. During this process, dewatering and construction pose some challenges. Previous
experience of sewer construction in the Maldives has indicated that excavation depths more
than 3.5m are not recommended for conventional dewatering methods to avoid the risk of
undermining and trench collapses as well as loss of structural integrity of the surrounding earth.
For the purpose of the Omadhoo design, the maximum depth of excavation will not exceed
3.5m as per the Design criteria and technical specifications for conventional gravity sewerage
systems guideline released by the Water and Sanitation Unit of the Environmental Protection
Agency (Environmental Protection Agency, 2015). Strict reference to these criteria will be
followed and necessary as the streets are very narrow and congested, leaving limited space for
mechanical excavation between buildings for the installation of pipelines.
Despite these shortcomings, the project does not pose serious threats to the natural
environment (marine and terrestrial) and will directly benefit the environment and the
community, both in the short and long term. Minor negative impacts with varying significance
will occur as the project is implemented. They include dewatering and localized salinization,
disruption to public transport, dust emissions during pipe laying work and reef damage during
the process of outfall construction. The pump stations have not been placed around the
periphery of the island, instead are located within the population zone. This could pose the issue
of foul odour in the event of a system failure whereby the foul odour abatement mechanism is
affected. Incorporating the pump stations in the populated areas is a necessity and this design
factor will enhance the functioning of the overall system.
The project will benefit the community and the island in the long term. It is important to
ensure that the project implementation is carried in a sustainable manner and in such the
sewerage system can be maintained in a cost effective manner as and when required. It is
therefore in the opinion of the consultant that the project does not foresee significant negative
environmental impacts and should be allowed.
Although the project will benefit the community, the proposed design has a number of
disadvantages. Construction of the sea outfall in the proposed location is seen as a social issue that could have hinder the local boat mooring activities as the pipe intersects a channel. Instead,
the sea outfall could be placed in between the channel and the jetty located on the southern side
of the island. Such social issues should be considered for better alternatives that justifies the
social, economic, technical and environmental values.
Sanitation systems must be both environmentally and socially friendly and acceptable.
As important as the design is the operation and maintenance. Operation and maintenance should
be viewed as a key sustainable aspect of similar projects. No matter how good a design is, the
sustainability and acceptability will depend on how good the system functions in the operational
period. With the pump stations being located on the road itself, there are a number of such
difficulties which are equally as important as the engineering design aspects. |