Whenever there is heavy rain in the capital city, the sewer starts spilling onto Norzin Lam and in other roads of Thimphu.  According to the Thimphu Thromde, the Norzin Lam redevelopment plan and extension of sewer lines are expected to address the issue.

Even before the start of the monsoon season, roads are flooded with human excreta. The recent sewer overflow was near the Centenary Farmers’ Market (CFM).

A Thimphu resident, Sonam Dorji, said that poor planning of the sewage lines and the increasing number of houses in the city overburdened the sewage tanks. “It is disgusting to see the roads flooded with faeces,” he said.

Untreated sewage contains water; nutrients (nitrogen and phosphorus); solids (including organic matter); pathogens (including bacteria, viruses and protozoa); helminths (intestinal worms and worm-like parasites); oils and greases; runoff from streets, parking lots and roofs; heavy metals (including mercury, cadmium, lead, chromium, copper) and many toxic chemicals, including pesticides, phenols and chlorinated organics. All these pose threats to human life, residents said. 

Thimphu Thromde’s chief engineer, Yeshi Wangdi, said that with the Norzin Lam redevelopment plan the issue of the overflowing sewer would be addressed. “The redevelopment project will replace the old sewage pipes that were laid in the 1990s,” he said.

The redevelopment project will also draw cable ducts underground.

While the redevelopment plan is yet to be implemented, Thromde has identified a team to clear the clogged drains and sewer lines.

Yeshi Wangdi said that the thromde would divert the sewage line near the Tarayana office building in Chubachu, directly to the Lungtenzampa treatment plan to avoid pressure on the sewage line in the CFM area.

Connecting the roof gutter line to the main sewage line and poor maintenance of the inspection chamber were some factors that cause the overflowing, according to Yeshi Wangdi.

“The inspection chambers, connecting a house to a sewerage line, is poorly constructed and managed by keeping it open.”

Yeshi Wangdi said that the waste littered gets washed into the inspection chamber increasing the water volume inside the sewage lines.

The thromde will strictly monitor the gutter line and the inspection chambers, he said, and fine penalty to the defaulters.

Yeshi Wangdi said: “If there were technical error in the design of the sewer lines then even when it does not rain there would be issues but, we have hardly faced any during those times.”

In the case of overflowing sewage tanks in the CFM area, Yeshi Wangdi said it could be because of the oil residues collecting inside the pipes decreasing its capacity.


By Chhimi Dema