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Title: | Environmental impact assessment for the proposed additional desalination facilities at Malé City, Kaafu Atoll, Maldives |
Authors: | Sandcays |
Keywords: | Desalination plants Legislative and regulatory considerations Existing environment Constructional impacts Operational impacts Mitigation measures Environmental monitoring Environmental impact assessments |
Issue Date: | Apr-2016 |
Citation: | Sandcays. (2016). Environmental impact assessment for the proposed additional desalination facilities at Malé City, Kaafu Atoll, Maldives. Male': Maldives |
Abstract: | This report discusses the findings of a social and environmental impact study under the
proposed project for setting up 2 new desalination plants with 5 additional boreholes in Malé
City. The project is proposed by Malé Water and Sewerage Company Ltd.
The proposed project involves establishing two new reverse osmosis desalination plants to
add to the existing capacity in Malé to cater for the ever increasing demand. 5000 tons per day
plant will be installed at the MWSC warehouse facility in Ameenee Magu and 2000 tons per
day plant will be installed in the Haveeree Hingun site which is also a designated site for
MWSC. Each plant will have sufficient number of boreholes to cater for the demand with 3
boreholes in the MWSC warehouse plot and 2 boreholes in the Haveeree Hingun site. The use
of boreholes will overcome the need for sedimentation tanks. Given the restriction in space
difficulties in laying intake pipes from sea, borehole is proposed for feed water. Desalination
based on reverse osmosis technology is the same technology used in Malé currently and has
been considered as the most suitable. RO desalination plant has recovery rate of no less than
40%.
The proposed drilling method for boreholes is Rotary Mud Drilling; the drill bit is attached to
the drill rod while being rotated and advanced into the borehole while pumping a drill mud
consisting of bentonite or polymer slurry into the borehole.
The project activities include clearing out the existing structures from the sites, mobilization
of equipment and materials to the site, plant set up, borehole drilling and setting up of storage
tanks.
The project duration proposed is 6 months from the start of construction. The general
construction materials and specific components that would be required for the project have
been identified in the project. Major project output is brine discharge and small amounts of
construction waste. Brine from the Ameenee Magu site will be discharged to the lagoon on
the southern side which is also used as a harbour. The Haveeree Hingun site brine outfall is
located on the north western end of Malé out from the harbor walls.
Alternatives have been identified in the project document. Of these alternatives, the
recommended alternative would be using sewage outfall pipe to dispose the brine as the
proposed lagoon do not have much of a current hence, poses low dilution potential.
Nonetheless, the brine outfall locations are devoid of marine life and is on the vicinity of
harbours the impacts would be negligible.
Alternatives for feed water have been discussed as obtaining from sea compared to the
proposed method of boreholes. Given the need for sedimentation tanks and the quality of
water obtained the use of boreholes has been proposed. Sedimentation tanks require a large
space and space constraints in Malé renders the option unfeasible. Borehole drilling methods
including manual drilling, jetting, precussion drilling and rotary drilling have been discussed
out of which rotary drilling, which is the proposed option, has been considered as the
preferred option.
The proposed project is to meet the water demands of Malé City and is an improvement to the
quality of services provided by MWSC to the public.
It is inevitable that there would be some negative environmental impacts. However, most of
the impacts of the proposed project are minor to negligible 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 project. Monitoring is specifically focussed on water quality, to
include feedwater from the borehole (or other source and seawater at brine discharge location
(upstream and downstream). Reef or marine ecological monitoring may be considered if the
proposed location of the brine discharge or intake is found to be of ecological significance.
In conclusion, it is justified from a technical and environmental point of view, to carry out the
proposed project to install and operate 2 desalination plants of a total capacity of 7000tonnes
per day. |
URI: | http://saruna.mnu.edu.mv/jspui/handle/123456789/4490 |
Appears in Collections: | ތިމާވެށި Environment A
|
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