A stretch of Park Street right outside The Park hotel has been barricaded following the collapse of an underground brick sewer line. The civic body has begun repairs and expects the barricades to remain for about a fortnight before reopening the road to traffic.

The issue surfaced on Friday when a leak was noticed, prompting repair work to start on Saturday.

“A portion of the century-old brick sewer line has collapsed. We have repaired the damaged section and built a manhole on the road above it. The concrete casting of the manhole and strengthening will take about two weeks,” a Kolkata Municipal Corporation (KMC) official said.

For the repair, the KMC dug a 4-meter-wide and 12-meter-long trench, resulting in the barricading of a wider stretch of the road.

The collapse of such brick sewer lines is not uncommon, explained a KMC official.

“This happens due to underground soil disturbance or leaks in water or sewer lines. Leaking water erodes the soil’s compactness, which leads to the collapse of the brick sewer section,” the official said.

The affected sewer line beneath Park Street is 100mm in diameter. “This network carries sewage and rainwater from a stretch of JL Nehru Road (Chowringhee) and Park Street to the drainage pumping station in Park Circus, called Ballygunge Drainage Pumping Station, and Palmer Bazar,” said a KMC official.

Calcutta has a combined sewer system, carrying both sewage and rainwater.

Kolkata Police’s South Traffic Guard said they apprehended congestion due to the barricades on Park Streets but traffic has been flowing normally.

“But rush hour congestion is expected on Friday and Saturday evenings. There will be enough personnel deployed on Park Street to manage the traffic,” said a police officer.

The city’s brick sewer system, built by the British between 1878 and 1888, spans an 88km network of “man-entry” sewers — large enough for maintenance workers to enter. The Park Street sewer falls under this category. There is also a separate network of narrower brick sewers beneath other roads.

In April, a similar collapse occurred under Camac Street.