City’s murky waters need clearing

By Chan Shun-kuei 詹順貴  / 

Sat, Oct 24, 2015 - Page 8

Two months after the devastation brought by Typhoon Soudelor, the turbidity level of the Nanshih River (南勢溪) — Taipei’s main source of tap water — remains stubbornly high. The enduring problem led Taipei Mayor Ko Wen-je (柯文哲) to change direction on the issue. He has announced plans to spend NT$2 billion (US$61.5 million) to connect a pipeline directly to the Feitsui Reservoir (翡翠水庫) to bypass the muddy Nanshih River.

However, the plan would not provide a comprehensive solution to the problem.

In the past, after a typhoon has directly struck northern Taiwan, the turbidity level of the Nanshih River usually falls back to 10 to 50 nephelometric turbidity units (NTU) within a day, so that only a moderate amount of chemical treatment is required to restore water clarity.

However, following Typhoon Soudelor, NTU levels of the river remained several hundred times above normal levels.

When Ko said at the end of last month that the city government, in that month alone, had spent NT$60 million on water purification chemicals, many people were concerned: What effect would the dramatic increase in the use of chemicals have on the health of Taipei residents? For how long would this situation continue? Is it really feasible to convert the Feitsui Reservoir into the main water source for Taipei? If not, how should the city government deal with the problem of worsening water quality in the Nanshih River? And are the landslides upstream the only cause for the murky water?

The questions concern the safety and quality of Taipei’s water sources and require further analysis.

First, the water purification chemicals that Ko talked about came in three main types.

Polyaluminium chloride is a chemical used to coagulate, absorb and precipitate sand, stones and other suspended matter to quickly purify water. Chlorine is then added to kill bacteria and disinfect the water, and finally a precipitant is administered to clear the sediment from the bottom of the reservoir. Because of the continuing high water turbidity, the amount of money spent on purification chemicals in one month has almost reached the amount that was spent for the whole of last year. Therefore, one can estimate that the amount of chemicals used during the purification process has increased by between 10 and 100 times the previously used quantity. However, despite the extra chemicals, the water is still not as clear as it should be.

The city government says that the amount of chemicals contained within Taipei’s drinking water falls within permissible levels.

However, polyaluminum chloride is a corrosive that is harmful to the environment. Also, its aluminum content has been identified as causing dementia. Would long-term consumption of water that contains chemical residues have an impact on health — especially on pregnant women and children?

Second, Ko’s plan to divert water from the Feitsui Reservoir — which lies downstream from Beishih River (北勢溪) — would take seven years to complete.

However, in 2006, the Taipei City Government completed the plans for the fifth phase of the Taipei area water supply strategy, which included a project to construct a second extension to draw water downstream from the reservoir.

Unfortunately, because former Taipei mayor Hau Lung-bin (郝龍斌) used the plan as an opportunity to request NT$3.2 billion from the central government, the project was aborted. Now Ko is seeking to resurrect the plan.

However, by adjusting part of the project’s route, the length of the pipeline has been shortened from 4.1km to 2.5km. It is therefore difficult to understand why it would take four years to complete the planning and environmental impact assessment (EIA) phase, and a further three years to build the pipeline.

Why not abandon the most difficult part of the project — constructing a tunnel, which would have the greatest impact on the environment — and instead run an underground pipeline along the edge of the river bank — or even a surface pipeline — and extend the water intake to the reservoir’s dam. This would reduce costs and vastly reduce the time required to conduct the EIA. The project would take no more than four years and the quality of the water would be better preserved.

Third, everyone is aware that these are difficult times for the nation’s economy. Taipei receives the largest proportion of central government budget allocations, while the Taipei Water Department turns a profit of between NT$500 million and NT$700 million annually. Since the department is able to cover its costs, why should the central government pick up the tab? If the central government were unwilling to pay, what would Ko do?

Fourth, in the past, the Beishih River has been found to be insufficient as a permanent water supply for Taipei. Even if water was drawn directly from the Feitsui Reservoir, it would only be able to function as a secondary water supply. The problem with the water quality of Nanshih River still needs to be addressed.

As for the landslides upstream, the government should not try to force the repairs through, or it would risk further disturbance to the slopes.

Officials can consider airborne seeding as a way to speed up natural recovery in the affected areas. Also, either Taipei City Government or the Forestry Bureau should crack down on illegal farming and construction that has encroached upon protected areas.

Finally, there is the uncontrolled discharge of wastewater in the Wulai (烏來) hot springs area, which has affected the water quality in the Nanshih River. Wulai Township (烏來) has only a single, rudimentary wastewater processing facility, which handles only part of the wastewater created by households and law-abiding hot spring businesses.

However, two-thirds of local businesses have long been violating the law and have been illegally discharging their wastewater — which includes dirty bath water, sewage and used cooking water — directly into the Nanshih River. This has led to an increase in the amount of chemicals used at water purification plants, which, in turn, has had an indirect impact on the health of Taipei residents.

Local government officials have failed to crack down on the chaotic and illegal situation in Wulai. The law should be applied without fear so that the problem can be resolved once and for all.

New Taipei City Mayor Eric Chu (朱立倫) has been in his post for five years. Before embarking upon a career change, he should first resolve the chaotic situation in Wulai, which has caused the residents of both Taipei and New Taipei City to be concerned over the safety of their drinking water. Instead of trying to pull the wool over people’s eyes, Ko should consider the health of Taipei residents and monitor the amount of chemicals used in the water supply. He should also implement the plan to draw water directly from the Feitsui Reservoir dam, allocate a budget, carry out the EIA and start construction. It would benefit Taipei residents considerably.

Chan Shun-kuei is a former member of the Environmental Protection Administration’s environmental evaluation committee and a legislator-at-large candidate for the Green Party-Social Democratic Party Alliance.

Translated by Edward Jones