Discovering the 'giant' underground sewer line under the To Lich River

The 15km underground sewer line of the Yen Xa Wastewater Treatment Plant project has been completed, preparing to rescue the polluted To Lich River. Special technology has also been applied for the first time to a project in Hanoi .

Eight years since the start of construction, the Yen Xa Wastewater Treatment Plant project (Thanh Tri district, Hanoi) is urgently completing many important items for trial operation at the end of this year.

The project is divided into 4 packages, of which package 2 is the construction of a wastewater collection system for To Lich River, constructed by Tekken Company (Japan). This package started on March 16, 2020, and has reached 93% progress to date.

With this package, the contractor will construct and install an underground sewer system running along the To Lich River, starting from Hoang Quoc Viet intersection to the end point at the junction of To Lich River - Lu River in Hoang Mai District (location in photo).

The unit used the open excavation method for a small part of the route, and the rest applied new technology of underground drilling with robots.

With underground jacking technology, the contractor will initially dig wells vertically, reinforce them with sheet piles, then send robots to the bottom of the wells and drill horizontally to connect the wells together.

The underground sewer connecting the two wells at the intersection of To Lich River and Lu River has the longest distance (550m), located at a depth of 13.44m from the road surface. The sewer shell is made of concrete coated with epoxy paint to prevent water and corrosion.

On the route running along To Lich River, the sewer line will change depth at different locations and have many points running under the bottom of To Lich River.

Mr. Chong Jiun Yiat, Project Director of Package 2, said that this is the first time underground drilling technology has been applied to a project in Hanoi. With this package, Tekken has completed 100% of the excavation and underground drilling construction items, with the remaining progress reaching 87% of the manhole construction progress and 85% of the branch sewer installation items.

The contractor is racing to complete the work by the end of this year. The biggest problem at present is that Hanoi has terminated the contract with the contractor for package 3 (installation of the sewer system on the Lu River). Therefore, Tekken said that the installation of manholes at the junction of the Lu River and the To Lich River has not been completed.

At the underground well location, the unit also designed a road up and down the sewer to serve the construction process. Mr. Chong assessed that the well construction is the most difficult item of this package, because during the implementation process, the contractor must relocate many utility works on the ground such as water supply pipes, drainage pipes, telecommunication cables, electric wires...

The unit both constructs and monitors whether the drilling and jacking affects the infrastructure above ground or not.

On April 16, Secretary of the Hanoi Party Committee Dinh Tien Dung and his delegation inspected the construction site of Package 2, directly inspecting the underground sewer system under the To Lich River at the intersection of the Lu River and To Lich River (Photo: Hanoi Moi).

After passing through the sewer system, the wastewater will be led to Yen Xa Wastewater Treatment Plant. The construction of this plant (package 1) has been completed 96%, waiting for synchronous connection with packages 2 and 4 (construction of sewer system for part of Ha Dong area and new urban area) for trial operation this year.

The Management Board of Investment Projects for Construction of Technical Infrastructure and Agriculture of Hanoi City (investor) is also requesting the Hanoi Department of Construction to soon give its opinion on the policy of continuing to invest in 9 primary settling tanks and 6 gravity sludge compression tanks using the city's capital.

This is to ensure the completion of the plant's treatment process, water replenishment solutions and sludge treatment technology according to the city's direction.

Diagram of wastewater drainage system from To Lich River to Yen Xa Wastewater Treatment Plant (Graphic: Ngoc Tan).

Once operational, the project will help treat domestic wastewater in seven districts: Hai Ba Trung, Dong Da, Ba Dinh, Tay Ho, Cau Giay, Ha Dong and Thanh Tri. Hanoi also hopes that the project will "rescue" the capital's polluted rivers, including the To Lich, Lu, Set and part of the Nhue rivers.

Yen Xa wastewater treatment system project includes construction of a wastewater treatment plant with a capacity of 270,000m3/day and night; construction of a sewer collection system, sewer interceptor and connection system (along both sides of To Lich and Lu rivers), and Ha Dong new urban area. Total length is about 52.62km.

In which, the factory is built in Thanh Liet commune, Thanh Tri district with an area of ​​about 13.8 hectares.

The total investment of the project is 16,293 billion VND, with more than 84% being ODA loans from the Japanese Government .

The project was launched in 2016, with the target of completion in 2020, but was delayed to 2022 but has yet to be operational. Hanoi has set a new deadline for the system to be operational by 2025.

According to Dan Tri

Source: https://tienphong.vn/kham-pha-tuyen-cong-ngam-khong-lo-duoi-long-song-to-lich-post1630152.tpo