民間參與方式執行污水下水道建設之財務評估比較研究 -以淡水污水下水道系統為例

Progressive Finance Study on Sewer System PPP Project based on Case Study of Tamsui Sewer System

張修銘(Shiu-Ming Chang)

指導教授 ： 曾惠斌

國立臺灣大學/工學院/土木工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.01117

摘要

污水下水道是城市文明生活的象徵，但臺灣地區係1980年代才開始推動污水下水道建設。在臺灣經濟蓬勃發展之當時，河川已同時遭受嚴重污染，而污水下水道普及率亦為瑞士洛桑管理學院評估世界各國之國家競爭力的指標之一，故臺灣始開始大力推動污水下水道建設，以改善民眾居住環境及河川水質。

在國內各項重大建設紛紛推動的同時，污水下水道所需經費相當龐大，初步統計臺灣地區每提高1％的污水下水道普及率即需投入新台幣近百億元，故從高鐵建設採用促進民間參與（BOT）方式執行以後，污水下水道建設可否比照導入BOT方式執行，即以公私協力(PPP)的概念共同完成公共建設及提供公共服務，即成研究課題。一般認為以BOT方式執行就是由特許廠商貸款興建營運並利用收費機制來滿足其資金投入成本及得到一定之報酬，且政府僅是提供特許權及特許年限，卻不必支付廠商費用及可取得該項公共服務。但實際上污水下水道以BOT方式執行，卻因廠商並無向使用民眾訂價收費之機制導致其自償性不足，反而執行方式是由政府出資給付特許廠商，以購買特定之公共服務。這種方式類似英國實施有年的PFI制度，由政府向廠商購買公共服務，但在臺灣因高鐵BOT案例，外界常將兩者搞混。

而BOT案件於投資前均經可行性評估，本文除資料文獻蒐集整理以外，並參考淡水污水下水道系統之特許公司執行至今的現況與投標前的財務規劃做比較，經蒐集迄今之財務報表並予以合理假設未來之相關參數後以折現現金流法可得知，污水下水道系統以BOT方式執行時，對於可計費之處理水量估算過於樂觀，很可能導致特許公司必須再融資以滿足特許期間之資金需求，並報酬率仍較原估算低很多。其原因在於估算水量的基準未符合社會現況，故如再有類似案件欲以BOT方式執行時，因自償率偏低，仍應正名為PFI案件，以減少和BOT案件的混淆，並對計畫收入基準即每戶人數予以修正下調，同時嚴謹調查及推估服務人口數，方能貼近未來實際可能發生之財務結果，降低投資風險。

關鍵字

污水下水道 ； BOT ； PPP ； PFI ； 報酬率

並列摘要

Sewer is a symbol of urban civilized life; however, Taiwan promoted construction of sewer since 1980s. With prosperous development of economy, Taiwan’s rivers have suffered from serious pollution. Popularity rate of sewer is also one of the indicators for Switzerland Lausanne International Institute for Management Development business school to evaluate the national competitiveness of the worldwide countries, thus Taiwan starts to promote construction of sewer greatly, so as to improve living environment and water quality of rivers.

When domestic major constructions are promoted, the sewer requires a large amount of expenditure. According to the preliminary statistics, it needs to invest NTD 10 billion to promote 1% of sewer popularity rate. After high-speed rail construction adopts BOT, it has become a research topic about whether sewer construction can be executed by referring to BOT, namely, jointly completing public construction and providing public service in the concept of PPP. It is generally thought that execution through BOT is that the authorized manufacturers build, operate and utilize charge mechanism to meet investment and gain certain return, and the government only provides authorization and sets limits on period to gain the public service without paying cost to manufacturers. In fact, if sewer is executed through BOT, self-liquidating capacity of manufacturers is insufficient because they have no charge mechanism for the public. As a result, the government pays to the authorized manufacturers to purchase the specific public service. This method is similar to PFI system carried out in England for years, in which the government purchases public service from manufacturers. However, people usually confuse these two due to the case of high-speed rail BOT.

BOT case is conducted with feasibility assessment before investment. In addition to collecting and sorting materials and literatures, this paper compares the current situation of authorized companies under Tamsui Sewer System with the financial planning before bidding. After collection of financial statement up to now and reasonable assumption of future related parameters, it can be known through discounted cash flow that the estimate on disposal amount of chargeable water is too optimistic when the sewer system is executed through BOT. It may possibly cause the authorized companies to conduct refinancing to meet fund demand during the authorized period, but rate of return is still much lower than the original estimate. That is because the standard of estimating water quantity does not conform to social current situation. Therefore, if a similar case is executed through BOT, it shall be named as PFI case due to lower self-liquidating rate, so as to prevent confusion with BOT cases. Moreover, the standard of planned income and number of people per household shall be reduced. At the same time, it can keep close to the possible financial result in the future and reduce investment risk only through rigorously investigating and estimating number of service population.

並列關鍵字

Sewer ； BOT ； PPT ； PFI ； Rate of Return

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