New Tuas desalination plant to have 'slight negative impact' on marine life

Leong Wee Keat Today Online 7 Feb 11;

SINGAPORE - The construction of the second desalination plant at Tuas - which, when complete, would provide another viable source of water supply for Singapore - may have "a slight negative impact" on marine life, in particular, fish.

This, according to an environmental impact assessment study that was commissioned by national water agency PUB. The study was conducted by DHI Water and Environment over six months and its128-page report has been accepted by the PUB.

Among its findings: Habitat loss is also expected for plants and animals living at the bottom of the sea measuring more than 0.5mm in length - known as microbenthics - but they are predicted to recover in the short term.

Regarding water quality, the study noted that iron oxides, total suspended solids and boron at the plant's offshore diffuser as well as within a 10m mixing zone will exceed the National Environment Agency (NEA) Trade Effluent Discharge Standards.

A waiver has been agreed in principle with the NEA to permit the exceeding of these standards within the 10m mixing zone.

Desalination, the process of removing salt and other minerals from water to make it drinkable, is set to grow by 10 times and meet 30 per-cent of the water demand by 2060.

The PUB expects the Tuas Desalination Plant to add another 70 million gallons (318,500 cubic metres) of desalinated water a day to the nation's water supply when it is completed by 2013.

The tender to design, build, own and operate the plant will be awarded by March.

The Tuas desalination plant will be constructed within a 14-hectare plot of land at Tuas View, adjacent to the western straits of Johor and lies 850m offshore from the Singapore-Malaysia International Boundary.

The surrounding Singapore coastline comprises various industrial facilities, Tuas jetty and Raffles Marina.

However, there are no nature reserves within 5km of the proposed plant.

Construction is expected to last for a year and the presence of construction vessels may temporarily affect recreational boats from Raffles Marine plying the Tuas shoreline, said the report, which also expects the plant operator to complete a formal safety assessment to manage any risk of collisions during works.

However, the DHI study predicts no navigation and cross-border impact.

Asked if it had concerns over the plant's discharge, which could be swept by tides to other coastal areas, the PUB told MediaCorp that the plant has to meet the environmental requirement of diluting the outfall discharge stream within 10m of its diffuser.

Said a PUB spokesperson: "As such, after the 10m mixing zone, seawater quality will be back to ambient levels and no environmental impact is expected."

For now, DHI felt that no further mitigation measures are required but recommended some measures the plant should take under its environment management plan. These include regular monitoring of ambient seawater quality, sediment and discharge during the construction and operations.

Related link
Pollution Control Study for Tuas Desalination and Power Plant Project (pdf)
70 MGD Desalination Design Build Own Operate (DBOO) Project Tuas Singapore, Natural Gas Power Plant and R & D Facility
Prepared for TuasSpring Pte Ltd FINAL REPORT:31 AUGUST 2011