VietNamNet Bridge – As many underground works, including subways and parking lots, are now under construction in HCM City, the public is questioning the quality and safety of the works, particularly after heavy rains that cause flooding.

Recent rains, for example, inundated the basement of a building, causing one death and damaging many cars.

However, city officials have assured the public.

“People should not be too worried about the safety of underground works,” said Hoang Minh Tri, deputy head of the HCM City Development Research Institute.

“With modern civil engineering technology, underground works will be safe from heavy rains,” he said, adding that no problems had occurred with the Thu Thiem Tunnel across the Saigon River, which is dozens of meters below the river bed, or to the high-rises near it.

Ho Long Phi, deputy director of the HCM City Anti-flooding Steering Committee, also said that modern technology used in construction projects includes walls that lead the water flow to certain points.

Phi assured the public that the subway system in HCM City would be safe for people, though it is deep underground.

The pump system at the Nguyen Huu Canh Tunnel in Binh Thanh district, for example, has been working well since the day it was installed. No flooding has been reported since its opening.

Tri said the flooding of the basement of the building in HCM City after the recent heavy rains was caused by technical errors made during construction of the building.

However, while saying that construction works were protected by modern technologies, Tri said the works should be dealt with in a more effective way in the context of climate change and rising sea water levels.

The panels installed to protect subways and the high staircases at the metro’s entrances, though solid, can prevent water from entering only at certain levels.

The city’s sewer systems installed in the Nhieu Loc – Thi Nghe, Tau Hu – Ben Nghe canal area, for example, are designed to ensure water drainage for rainfall of 80-85 mm over a maximum three-hour period.

However, the recent heavy rains overloaded the drainage systems in a very short period of time.

Over the years, many solutions have been suggested to settle flooding, including building underground water reservoirs and installing pump systems.

Twenty years ago, the building of a water reservoir system was mentioned in a drainage system development program drawn up by JICA (Japan International Cooperation Agency). The reservoirs have also been mentioned in the HCM City Development Plan which extends until 2020.

However, no considerable progress has been made over the last four years, since the day the plan was approved by the Prime Minister.

No water reservoir has been built, except several small ones upgraded from existing lakes in parks.

Thien Nhien