Fighting salinity: Ctg Wasa plans $400m project to ensure clean water supply

Infograph: TBS

Chattogram Wasa has planned an ambitious $400 million project to address the salinity issue, resulting from climate change, to ensure clean drinking water for the residents of the port city.

Officials said two international lending agencies – the Economic Development Cooperation Fund (EDCF) of Korea and the Japan International Cooperation Agency (Jica) – have shown interest in supporting and implementing the project.

A concept note titled "Chattogram Wasa Improvement Project (CWIP)" has been developed in collaboration with SUEZ, a consulting firm headquartered in France.

The note has proposed the construction of intake stations, pipelines, and new water treatment plants to extract water from the surface of the Karnaphuli River.

According to Ctg Wasa sources, the port city experiences significant fresh water crisis during this summer. The escalating salinity levels in the water of this coastal city poses substantial challenges for the authorities in ensuring the production of clean drinking water.

Insufficient rainfall resulted in an increase in salinity in the Karnaphuli and Halda rivers, which are the major water sources for Chattogram Wasa, they said.

Chattogram Wasa usually faces salinity crisis for 15-20 days every year, especially during the summer. However, this year, due to low rainfall and low discharge of water from the Karnaphuli hydropower plant in Kaptai, salinity lasted for about three months.

AKM Fazlullah, managing director of Chattogram Wasa, emphasised the urgency of addressing the salinity crisis created by climate change.

"We need to take immediate action, as the situation is likely to worsen in the coming years. Discussion is currently going on with the donour agencies. They are reviewing the issue," he said.

What's the plan?

The SUEZ concept note proposes the construction of alternative intake stations and the establishment of new treatment facilities to address salinity-related concerns, said Ctg Wasa officials.

Keeping the future water demand in mind, the concept note recommended to build infrastructures in three parts.

The first part involves the construction of an intake station and a pre-settlement reservoir at Vandaljuri to gather 84 crore litres of untreated water per day.

An intake station is a structure that withdraws water from a source, such as a river or lake, and delivers it to a water treatment plant or distribution system.

Additionally, the concept note suggested the establishment of a pump station with a capacity of 63 crore litres per day.

The concept note also proposed the construction of a river crossing pipeline beneath the Karnaphuli and Halda Rivers, connecting Mohra to Madunaghat, with a daily capacity of 42 crore litres.

Additionally, it suggests the establishment of a new water treatment plant in Mohra, capable of producing 20 crore litres per day.

Besides, the concept note recommends the installation of a pipeline stretching from Mohra to Bayezid Link Road to enhance service coverage.

Furthermore, it suggested the construction of two additional treatment plants in the second and third phases of the plan in the area of the Mohra water treatment plant.

Makshud Alam, chief engineer of Chattogram Wasa, mentioned that a Preliminary Development Project Proposal (PDPP) is currently being prepared based on the concept paper.

"The PDPP is expected to be submitted to the Economic Relations Department (ERD) this month. Following that, the proposal will undergo review by donour agencies, and feasibility studies will commence accordingly," he said.

He highlighted the global practice of using the reverse osmosis method for desalination, which can be expensive.

He said that there is no need for costly water treatment plants solely dedicated to removing salinity, especially considering that salinity is a concern for only 2-3 months in a year.

Deteriorating salinity crisis

Since 1994, Chattogram city dwellers have been facing salinity problem almost every year. In the dry season, when the river doesn't get enough upstream water, it fills the deficit by pulling up saline water from the Bay of Bengal.

However, in March this year, excessive salinity in the Halda River water forced the Ctg Wasa to stop the operation of its Mohra Water Treatment Plant for a certain period every day, which caused a decline in water supply for the city people.

Ctg Wasa officials said sea level rise and decrease of water flow from upstream due to the impact of climate change, salt-mixed tidal water enters the Halda River.

Currently, Ctg Wasa collects untreated water from three intake stations to supply to four treatment plants.

Among these, the Rangunia intake station has a daily capacity of 30 crore litres, while the Mohra and Madunaghat intake stations each have a capacity of 9 crore litres.

Additionally, there is an intake station currently under construction at Boalkhali, as part of the Vandaljuri water supply project, which will have a capacity of 6.6 crore litres per day.

According to engineers from Chattogram Wasa, the Mohra and Madunaghat intake stations are vulnerable to salinity issues, primarily caused by insufficient rainfall during the summer season and reduced discharge flow from the Kaptai hydroelectric plant.

Under normal circumstances, the salinity level ranges from 200 to 300mg per litre. However, during the summer, it significantly rises to 1,500-1,800mg per litre, making the water highly saline and unsuitable for treatment.

Capacity of Ctg Wasa

Currently, Chattogram Wasa has a daily water production capacity of around 46 crore litres.

The Sheikh Russel Water Treatment Plant contributes 9 crore litres, while the Sheikh Hasina Water Treatment Plant and Sheikh Hasina Water Treatment Plant-2 each produce 14.3 crore litres. Additionally, the Mohora Water Treatment Plant provides 9 crore litres of water daily.

Chattogram Wasa currently have 78,542 residential connections and 7,767 commercial connections. The demand for water supply is steadily increasing, with an annual growth of approximately 5 crore litres.

Consequently, the daily water demand is projected to reach 63 crore litres by 2032 and 122 crore litres by 2042.