傾斜土壤氣體監測井應用於 大型地面儲油槽洩漏監測效益評估

大型地面儲油槽洩漏導致地下水受污染物侵入之案例國際間時有所聞，且因為其高寬比相當低，導致其日洩漏量對應之儲油槽液面高度變化極小，不易藉由液面計監測察覺滲漏且因槽體面積大，若由儲槽底部滲漏，不易偵測。為有效監測大型地面儲油槽洩漏，本研究主要探討將適用於加油站油品滲漏監測之土壤氣體監測井 (Soil Vapor Monitoring Well)運用於大型地面儲油槽滲漏監測，並以數值模擬軟體 (TMVOC)針對多種不同地質與水文條件之假設場址模型進行模擬，以瞭解常見污染物的傳輸行為，進而驗證土壤氣體監測井應用於大型地面儲油槽洩漏監測之效益，並比較垂直與傾斜土壤氣體監測井之監測情形差異。本研究結果顯示多數情境下土壤氣體監測井可以有效測得大型地面儲油槽之洩漏，且傾斜土壤氣體監測井到達警戒濃度濃度 (500ppmV)所需時間明顯較垂直土壤氣體監測井短。於相同地質條件下，地下水位越深，油品、油氣污染傳輸速率較快。滲透係數較大者其污染團氣相之垂直傳輸速率相對較快速滲透係數較小者其污染團氣相之水平傳輸速率相對較快速。且土壤氣體監測井距離油品洩漏點越近其監測效果較佳。此外，本研究發現汙染物氣體濃度對時間之微分與二次微分能提早反應洩漏，並提供未來研究方向之建議。

關鍵字

NAPL ；地面儲槽；土壤氣體監測井

並列摘要

Literature has revealed that the leakage of aboveground storage tank is one of the major sources that caused groundwater pollution. The of leakages are hard to be detected by the level gauge due to the small height-width ratio of the bulk storages. In addition, it is also difficult to detect the leakage due to defects at the bottom of the tank due to its huge area. Therefore, this research aims on to verify the effectivenss and efficiency of using soil vapor monitoring well for the aboveground storage tank leak detection. Several scenarios with different soil and groundwater conditions have been simulated by using TMVOC in this research, and the comparisons between vertical and incline vapor monitoring well have been carried out. The results suggest the soil vapor monitoring well is effective for aboveground bulk storage tank monitoring, and the incline well responds significantly earlier than the vertical well in most of the scenarios simulated. The spreading speed of oil and gas in the ground increased due to the increment of the ground water table depth. When transporting in a well hydraulic conductive soil, the spreading of gas speed is relatively high in vertical direction, and vice versa. Additionally, the result also suggests the differential and double-differential of concentration react earlier due to the leakage, which suggest a possible application in the future.