Influence of Water Table Fluctuation on Gasoline Distribution

• Main Authors: Li, Ming-Fu, 黎明福
• Other Authors: Chia-Shyun Chen
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/48166123562093187337

碩士 === 國立中央大學 === 應用地質研究所 === 86 === This paper discusses the influence of water table fluctuation on redistribution and movement of gasoline in the subsurface and in the monitoring well, and the development of analytical relations for the gasoline volume contained in soil with or without free product. Relevant dynamic problems were studied with sand-box simulations, while equilibrium problems by mathematical analysis. Fluids inside the monitoring well move faster than do they in the surrounding soil as the water table fluctuates. Therefore, gasoline thickness in the monitoring well decreases as gasoline flows into the surrounding soil when the water table rises due to regional groundwater flow, and vice versa. If the rising of the water table is caused by infiltration from rain fall or surface recharge, gasoline thickness inside the monitoring well does not increase significantly. When regional groundwater flow causes the water table to rise, residual saturation of gasoline is formed below the rising water table. As the water table falls, this residual saturation of gasoline is remobilized to accumulate on top of the falling water table. Analytical relations for the estimation of gasoline volume contained in soil with and without free product are obtained, and they all show gasoline volume in soil is related to soil characteristics, and invasion depth that is influenced by the leakage amount and the distance between the water table and the leakage source. Thus, effective application of remedial measures needs to know the water table fluctuates. Detailed field investigation of gasoline contamination requires monitoring wells as well as soil sampling data.