Building boom chokes Thimphu drains

With a population of around 700,000 living in a mountainous landscape cut through by rivers, Bhutan never had a problem with pollution. But in the last few decades, as economic growth has led to increasing urbanisation, this is changing. Nothing illustrates this better than Bhutan’s capital city, Thimphu, and the challenges it faces with wastewater management.

An ever expanding city

From a tiny beautiful town of around 10,000 people a few decades ago, Thimphu has transformed into a concrete modern city. According to the National Statistics Bureau (NSB) Thimphu had a population of 104,214 in 2010, and is growing at a rate of 1.3% per year. The NSB has predicted that the capital will continue to expand, as migration from villages becomes ever more popular.

Manka Bajaj’s thesis, “Growing Pains of Bhutan” on the building boom that lasted from 2008 to 2012 notes, “Less than a third of residents are born in Thimphu. While 32% of residents are from Thimphu, 58% come from [other parts of] Bhutan.” Bajaj’s research shows that as the city has expanded so have its problems. In 2008, the city had already finalised detailed urban plans. Unfortunately these ran up against the incentives of local actors, who were able to influence governing authorities to grant some leeway. Added to small contradictions in the plans, the problems have ballooned into large challenges as Thimphu has expanded to more than ten times its original size. It now covers 26 sq. km, or around the size of 16 villages, according to the official city profile.

Galey Norbu, chief urban planner of Thimphu city corporation (Thromde), told thethirdpole.net that the city approves the construction of about 150 buildings a year. He said most of the new buildings were required to build their own septic tanks and soak pits to manage wastewater. This is because the existing sewage treatment plant (STP) in Babesa does not have the capacity to take any more load. The STP will be decommissioned once a new treatment plant is built, funded by the Asian Development Bank.

Failure to adhere to regulations

Norbu said the treated sewage that goes into the river is clean and within acceptable limits according to World Health Organisation standards. “But we are increasingly observing that most landowners have not built their soak pits properly.” This has caused leakages, which affect the immediate neighbours of those that do not follow regulations. There are numerous complaints regarding this issue.

Samten Lhendup, deputy executive engineer in Thimphu’s sewerage and wastewater management department, told thethirdpole.net that the increasing number of residents and the construction boom has affected water usage, sewerage and management of wastewater. He said the general complaint from the public is with regards to the overflow of raw sewage from manholes. This is because people dispose of solid wastes like rags and plastics into the sewage channels, he explained. This blocks the sewage channels.

From manhole cover thieves to toxic landfill

The increasing population has resulted in more problems. Thieves have taken to stealing cast-iron manhole covers to sell to scrap dealers. Many residents illegally connect the drain from their roofs to the sewer system, adding a huge amount of flow as well as leaves and mulch into the system. Unused to sewer systems and considering it dirty, Bhutanese sweepers refuse to work in the sewers, leaving the city dependent on Indian nationals to do the job.  Lhendup added that the lack of funds to resolve wastewater management problems is another major challenge.

City officials said solid waste management was another major problem. Thimphu produces over 30 metric tons of waste a day, which is dumped at Memelakha landfill. Officials told the media they found Thimphu City’s only waste dumping site was generating toxins that were leaking into the ground. Since the landfill is located uphill of a tributary to the Thimphu River, the toxins flow directly into Thimphu River. This adds to a river already polluted by those washing vehicles on the banks, wastewater from automobile workshops flowing into the waters and open dumping of wastes into the river.

Yeshi Wangdi, the head of solid waste management, said that the city would extend the landfill and connect it to a new network of underground pipes to collect the leachate. “The issue of leachate generation during rainy season would be controlled with the new network of pipes underneath.” Collected in tanks, the leachate will be treated in the plant located at Babesa sewage tank. Japan International Cooperation Agency (JICA) is funding the project.

As wealth, generated through hydropower and tourism, continues to flow into Bhutan, the country will continue to grow and urbanise. Thimphu’s ability to handle and treat its waste will be key to making sure that the rivers of Bhutan run clean.