有害廢棄物新處理場址之系統效益評估

Abstract

評估新建有害廢棄物處理場場址一般只考量該場址對周圍環境與居民影響及相關因子或條件。然而新設一個處理場亦會影響整體的清運及有害廢棄物的流布，因而影響整個系統的風險。唯目前尚無評估新設處理場對整個系統效益的研究，故本研究依據各項因子研擬一套方法評估場址的系統效益，以改善有害廢棄物新設場址評估。 本研究首先進行場址評估，分為環境面、社會面、經濟面等三方面評分。之後針對區域性因子、危害性性因子及運輸風險因子進行分析。區域性因子主要考量各類廢棄物產生量、區內或跨區處理量;危害性因子主要依據各類有害廢棄物的主要成分的NFPA值及危害分級建立數個指標評估其危害度；運輸風險因子則主要依據運輸距離、沿線人口及道路事故發生機率評估運輸風險。接著，依據前述三類因子進行新設場址的系統效益評估。最後依據場址和系統效益評估結果綜合比較各場址的適宜性。 本研究應用所建立的方法，針對一些案例進行場址及系統效益評估，且作綜合評估與評選，並採用最短距離及引力法模擬有害廢棄物在新場址設置後之重新分配，以示範及探討所建立的方法是否能改善新場址評估。根據結果發現傳統場址評估易忽略新場址對整個系統的影響，以本研究所建立的方法評估新場址適合度及整個運送系統的風險可有效改善選址決策品質，而針對單一類及混合類廢棄物進行分析，能依對整個系統的效益選擇較佳的場址。

Assessing a prospective hazardous waste treatment facility (HWTF) site generally considers only the impact on its surrounding environment, residents, and related factors or conditions. However, a new facility can significantly affect also the collection and distribution of hazardous wastes, and thus the potential risk posed on the entire system may be significantly altered too. No method is currently available for assessing the effect of a new facility on the entire system. This study is thus initiated to establish a method for estimating the system benefit of a new site by analyzing three essential factors. The proposed method is expected to improve the assessment of a candidate HWTF site. First, this study implements the conventional assessment based on several environmental, sociocultural, and economic factors for candidate sites. The proposed method is then applied to analyze spatial, hazard, and transportation risk factors. The spatial factor is evaluated according to the quantities of hazardous wastes transported and treated inside or outside a collection zone. The hazard factor is evaluated based on the NFPA hazard rank values of major representative chemicals of hazardous wastes, and several indexes are established to determine potential hazard levels. The transportation risk is estimated based on the transportation distance, population along passed roads, and the accidental rates of the roads. Then, the system benefit of a new site is estimated according to the three factors. Finally, the suitability of a candidate site is evaluated according to the results of the conventional site assessment and its system benefit. The established method is applied to assess several prospective sites and their system benefits. For each prospective site, hazardous wastes are redistributed based on the Shortest Distance approach and Gravitation approach. The applicability of the method for improving the site assessment of a HWTF site is demonstrated. According to the results, the traditional site assessment is easy to overlook how a new site affects the entire system. Other than assessing the suitability of a HWTF site, the method can be used to improve the quality of decision for selecting a new site. According to the cases implemented for both single and multiple category hazardous waste, the proposed method can facilitate the siting analysis to effectively identify the appropriate candidate site.