跳到主要內容 :::

年度	112	專案性質	實驗性質
專案類別	模場試驗	研究主題	整治
申請機構	淡江大學學校財團法人淡江大學	申請系所	水資源及環境工程學系
專案主持人	王聖瑋	職等/職稱	助理教授
專案中文名稱	建立地下水LNAPL傳導係數分析方法與優化抽除效率
中文關鍵字	地下水, LNAPL, 整治, 傳導係數, 提取試驗
專案英文名稱	Developing the analysis method of groundwater LNAPL Transmissivity for optimizing remediation efficiency
英文關鍵字	Groundwater, LNAPL, Remediation, Transmissivity, Bail-down test
執行金額	2,498,060元
執行期間	2024/1/1 至 2025/12/31
計畫中文摘要	油品污染初期常伴隨純相物質的存在，為了在整治初期快速移除輕質非水相液體(Light non-aqueous phase liquid, LNAPL)，通常採用抽出處理方式，以降低污染物擴散的風險。然而，由於LNAPL與水的化學性質迥異，若未能妥善評估LNAPL在地層中的傳導能力，可能導致抽出過程中的油水比例過低，進而延緩整治效果。為了評估LNAPL於含水層中的傳導能力，本計畫應用提取試驗(Bail-down test)進行現地測試，並規劃以不同解析方程式計算LNAPL的傳導係數(Transmissivity, T)。提取試驗主要適用於非固結、多孔沉積物中的LNAPL，T值代表單位寬度含水層中，每單位時間、單位洩降所通過的LNAPL體積。因此，T值可視為LNAPL回收潛力的評估指標，這與以往認為LNAPL厚度越厚回收效率越高的傳統觀念有所不同，因為不同的土壤類型、LNAPL類型及水文地質條件，皆可能對回收效果造成影響。目前台灣尚無相關研究針對提取試驗的實施，因此本計畫於第一年度進行國外文獻資料蒐集，並完成現地提取試驗的準備工作、前導試驗及正式提取試驗等工作。透過試驗獲得的LNAPL與地下水液位隨時間變化的數據顯示，井徑大小對設備操作有顯著影響，由於試驗場地的監測井井徑僅為2吋，導致原計劃中的整治泵與自計式液位測量設備無法同時安裝，因此改以油水介面尺進行液位測量。然而，這可能造成數據記錄時出現幾秒的時間間隔差異，進而影響液位數據收集的精度。此外，當井中的LNAPL油層厚度過薄時，容易受到人工測量及環境因素的影響，導致數據不穩定，回收操作也可能低估油層厚度，進而影響LNAPL體積的準確估算。特別是當油層較薄時，計算出的T值誤差可能過大，無法反映LNAPL的真實狀況，進而影響整治方案的評估與設計。最後，本計畫第一年度利用煎餅模型(Pancake Model)及垂直平衡模型(Vertical Equilibrium Model)估算地下水中油品的體積，分別為720.37 m3及2,829 m3。煎餅模型基於實際浮油厚度進行推算，而實際浮油厚度通常小於觀測厚度，導致其估算的LNAPL體積較低；垂直平衡模型則考慮毛細管作用與飽和度梯度，提供了更為合理的體積估算。
計畫英文摘要	In the early stages of oil pollution, pure-phase substances are often present. To rapidly remove light non-aqueous phase liquid (LNAPL) during initial remediation, extraction methods are typically employed to reduce the risk of pollutant migration. However, since the chemical properties of LNAPL differ significantly from water, failure to properly evaluate the transmissivity of LNAPL in the subsurface could result in a low oil-to-water extraction ratio, delaying remediation effectiveness. To assess LNAPL transmissivity in aquifers, this project applies the bail-down test for field testing and plans to use various analytical equations to calculate LNAPL transmissivity (T). The bail-down test is primarily suitable for unconsolidated, porous sediments containing LNAPL, and the T value represents the volume of LNAPL passing through a unit-width aquifer per unit of drawdown and per unit of time. Therefore, the T value is considered an indicator of LNAPL recovery potential, which contrasts with the traditional belief that thicker LNAPL layers result in higher recovery efficiency. In reality, different soil types, LNAPL characteristics, and hydrogeological conditions can all affect recovery outcomes. Currently, there is no related research on bail-down testing in Taiwan. Therefore, during the first year of this project, literature review and preparation for field tests were conducted, including preliminary testing and formal bail-down testing. The data obtained from these tests show the change in LNAPL and groundwater levels over time, highlighting the significant impact of well diameter on equipment operation. Since the monitoring well at the test site has a diameter of only 2 inches, the initially planned remediation pump and automatic water level measurement device could not be installed simultaneously. Therefore, a manual oil-water interface meter was used for liquid level measurements. However, this may have resulted in a few seconds of data recording lag, affecting the accuracy of liquid level data collection. Additionally, when the LNAPL layer in the well is too thin, manual measurements and environmental factors may cause data instability. Recovery operations may also underestimate the thickness of the oil layer, leading to inaccurate estimates of LNAPL volume. Particularly in the case of thin oil layers, the calculated T value may exhibit significant errors, failing to accurately reflect the true LNAPL conditions and potentially affecting the evaluation and design of remediation strategies. Finally, the project used two conceptual models, the Pancake Model and the Vertical Equilibrium Model, to estimate the volume of oil in groundwater, which was calculated to be 720.37 m3 and 2,829 m3, respectively. The Pancake Model is based on the actual floating oil thickness, which is usually less than the observed thickness, leading to a lower estimate of LNAPL volume. The Vertical Equilibrium Model, on the other hand, takes into account capillary forces and saturation gradients, providing a more reasonable volume estimate.