Technical Studies

The Pinglin wastewater treatment plant, being part of the sewer system at the upstream of Feitsui Reservoir, is located at the junction of Peishin River and Daiyujyue River. Tremendous lost incurred when Xangsane and Nari typhoon struck in year 2000 and 2001. The purpose of this plan is to investigate the appropriateness of the protection standard set for the flood wall of the wastewater treatment plant. In addition, this study tries to set a standard operation procedure required for emergency evacuation during the period of typhoon and flood.

Through rainfall-runoff analysis and hydrographic routing, it was concluded that changes of rain type, not the water level in Feitsui Reservoir, has a more apparent effect to the backwater phenomenon in Peishin river near the plant. In our research, the structural safety of the flood wall and the Return Periods were re-examined. The present flood control wall is below the design safety coefficient and its height (177.55m) does not match to the return period in year 2000. The warning stage was set at the location of the water meter at cross section 68, opposite of the transverse flood control gate. It has two control elevations, one being the elevation at the bottom of the transverse gate, the other being at the tip of the flood control wall. This research suggests changing the present six degree warning system into a three degree one. After calculation, the tertiary warning water level was set as 175.5 m (with one hour of early warning), the secondary warning stage as 176.5m (with three hours of early warning), and first warning state as 177.0 m (with one and half hours of early warning.)

After going through on-site investigation, holding of symposiums and interviews, this plan has set the corresponding emergency strategies in the reactive and standardized operation procedures (SOP) for evacuation during typhoon and heavy rain fall. In addition, educational manuals were edited and explanation meetings and rehearsal of emergency evacuations were held. The emergency reaction was classified into three degrees. The third warning level being: Issuing of land and sea warning for typhoon or heavy rain fall; or the observation of water level outside the plant being exceeded the tertiary warning water level, or receiving warning and orders from the Taipei Water Management Office (WRA, MOEA), to set up emergency group, shutting down of flood control gate and placement of sand bags, to execute: pumping of water, inspection and examination of electro-mechanical devices, factory area, disaster prevention materials, important equipments that need replacement. The second warning level being: observation of water level outside the plant being exceeded the secondary warning water level, or receiving warning and orders from the Taipei Water Management Office (WRA, MOEA), to set up emergency group meeting, to execute: pumping of water, inspection and examination of electro-mechanical devices, factory area, disaster prevention materials, important equipments that need replacement. The first warning level being: observation of water level outside the plant being exceeded the first warning water level, or receiving orders from the Taipei Water Management Office (WRA, MOEA) to shut down the main power system, remove important equipments accordingly to the second floor, evacuation of personnel to the second floor and if necessary, shutting down of the back up power.