According to the Management Board of the agricultural and technical infrastructure construction investment project (the investor), this pipeline was added by the city to the Yen Xa wastewater treatment system project. The project includes two parallel HDPE pipes with a diameter of D1200, taking water from West Lake's Gate A (Trich Sai street), running along the existing canal through lane 24 Vo Chi Cong, and emptying into the head of the To Lich river.

The pipeline is designed for regular replenishment, preventing mixing with wastewater in the canal. In the event of lowered water levels in West Lake, wastewater will still be separated and sent to the Yen Xa plant for treatment. The dam at Quang bridge (Thanh Liet ward) has been completed, and the sluice gate system can be lowered to maintain the river's water level. All wastewater drains along both riverbanks have also been collected and directed to the Yen Xa plant for treatment.

In addition to the water from West Lake, before 20/9, the To Lich river will receive treated water from the Yen Xa plant at a flow rate of approximately 200,000 m3/day. The river's water level will then be maintained at 3.5 m.

In February, the city assigned the Department of Construction to study the plan of drawing water from West Lake to supplement the To Lich river through the West Lake A regulating gate - Do culvert - Thuy Khue canal if necessary. To maintain stable water levels in West Lake, Tay Ho district was tasked with proposing supplementing water from the Red river and treated water from the West Lake plant. In the long term, the city has requested the Department of Construction to research a plan to channel water from the Red river along the Vo Chi Cong axis, both supplementing the To Lich river and regulating West Lake's water level.

The 13.4 km To Lich river begins at Nghia Do canal (Hoang Quoc Viet) and ends with two outlets: one into the Nhue river through Thanh Liet dam and the other into the Red river through the lower section of Kim Nguu river, leading to the Yen So pumping station with a capacity of 90 m3/s.

For years, Hanoi has implemented numerous solutions to treat pollution in the To Lich river, but without much success. Currently, the city is carrying out the Yen Xa (Thanh Tri) wastewater collection and treatment plant project to separate all wastewater and rainwater from the common drainage system to improve the quality of rivers, including the To Lich river.

Vo Hai