The wastewater stabilisation pond in Babesa, Thimphu, would be replaced with a sequencing batch reactor (SBR) treatment plant, an improved plant with larger capacity by May next year.
The current pond has a capacity of 1.75 million litres a day (MLD) while the new plant, which is being constructed nearby would have a capacity of 12MLD.
The existing pond catered to about 16,000 people while the SBR system is planned to cater to about 100,000 people especially from the south Thimphu area and core city area.
Thimphu thromde’s project manager for Asian Development Bank (ADB), Kinley Penjore, said the old plant has exceeded its capacity as well as received complaints of foul smell. The new pond, he said, is expected to address these issues.
He said that the new mechanised SBR system was chosen as there was no space to build another pond system which requires more space.
The SBR treatment plant would occupy about three acres, while the existing pond is on 14 acres land.
Kinley Penjore said that the new treatment plant would also have an odour control system.
ADB would fund 85 percent of the USD 14 million project cost while the finance ministry would fund the remaining 15 percent.
The project manager said that currently, designs of all components have been approved and about 10 percent of the project is completed. “The other major structures like head works, chlorination building and centrifuge building will start in a few months time.”
Works on the main structure of the plant, the SBR, is 15 percent completed.
He said that the construction site being next to the river poses a risk of the river breaching the banks and flooding the deep excavation works. “Thus, such activities have to be taken up during winter when the river discharge is low but expatriate workers’ reluctance to work during winter has hindered the work progress.”
The project manager said the contractor has managed to retain a number of workers during winter.
The existing pond, which has been in use since the early 1990s would be decommissioned once the SBR treatment plant is completed.