The construction work of Doulio City sewerage system is a turnkey project. Based on the wastewater catch basin of the city, two trunk sewers, A and B, are planned. The length of trunk sewer A is about 4,052m, while trunk sewer B is about 2,071m(deduct the bid part), both with diameters from ∮300mm to ∮1,000mm. Burying of trunk sewer in downtown area uses mainly pipe jacking. The section of trunk sewer buried across Yunlin River is constructed using open cut method with the help of a temporary cofferdam to divert flow.   Before backfilling, it is covered with reinforced concrete for protection.