The capital city plans to construct 39 waste treatment plants for urban areas with an expected capacity of 1.8 million cubic metres per day by 2030, stretching to nearly 2.5 million cubic metres per day by 2050.

The target falls under the city's drainage plan until 2030, with a vision towards 2050, which was recently approved by the Prime Minister.

The plan is estimated to be worth approximately 53.35 trillion VND (over 2.56 billion USD) by 2020 and 116.5 trillion VND (over 5.6 billion USD) by 2030.

According to the blueprint, the city will have three main drainage areas with the first being the Ta Day area encompassing drainage basins in the rivers of To Lich, Dong My, Ta Nhue, Huu Nhue, Phu Xuyen with an area of about 47,350 hectares.

The second is the Huu Day area including drainage basins of Son Tay, Xuan Mai, Hoa Lac, Quoc Oai, Phuc Tho and Chuc Son with an area of over 31,300 hectares; and, for the third, northern Hanoi with drainage basins in the districts of Long Bien, Gia Lam, Dong Anh, Me Linh and Soc Son in an area of over 46,700 hectares.

Although a number of sewage projects have been conducted, Hanoi still faces high risks of flooding during the rainy season.

Despite a sewage project in Tay Ho district's An Duong Street being completed last year, the local residents are still worried by the threat.

Nguyen Van Hoi, a resident who supervised the project, said sewage pipes were placed too deep, whereas some parts of An Duong Street are too low, meaning rain water will still converge on the street causing flooding.

Le Vu Quang Suong, an official of the Hanoi Sewerage and Drainage One-member Co Ltd said the sewage system had improved and was becoming better year by year.

However, the abnormal short heavy rains experienced since 2008 have meant the system's capacity was exceeded, preventing it from draining.

At present, the city's sewage system can drain rains of between 172-310mm per two days.

Phan Hoai Minh, Director of the Company, said, "Flooding in the city during heavy rains cannot be avoided as the rate of sewage pipes in the city is only 0.4-0.5 metres per person, 1.5-2m lower than other cities in the world."

The systems in new urban residential areas are not built based on their requirements and are subsequently substandard.

Moreover, the sewage system was often damaged when people discharged waste, stole drain covers and encroached on the system with their own construction work, he said.

Le Vu Quang Suong added that the company is conducting new sewage projects this year to partially reduce the flooding.

The sewage systems on Huynh Thuc Khang-Lang Ha, Tran Huy Lieu-Giang Vo and Dao Duy Anh-Hoang Tich Tri streets have all been improved in recent months.

Meanwhile, the second stage of the Yen So pumping station was completed and opened for use at the end of last year.

From the middle of May, the company will regularly supervise water levels in the sewage system to ensure they are ready for abnormal rains. The company will also join hands with relevant agencies to regulate the water levels in inner and suburban areas of the city.

Nguyen Hong Tien, Director of the Ministry of Construction's Technical Infrastructure Department, proposed designing a rain water collection system.

Flooding prevention should go hand-in-hand with recycling rain water, he said.

Tien added that construction management should be strengthened and investors should be supervised when building the sewage and drainage system.-VNA