Remediation of non-aqueous phase liquid wastes in groundwater systems containing trapped gas

清洁的水是国家的优先事项。数百万加拿大人依赖干净的地下水作为饮用水的来源。此外，由于土壤和地下水受到工业化学品的污染，加拿大数以万计的废弃房产中有许多仍然没有使用。通常，最难清理的场地是那些被石油燃料、溶剂、干洗液和煤焦油等化学品污染的地方，这些已知对人类健康构成重大风险。由于地下的复杂性以及污染物的物理和化学行为，清理这些地点是一项挑战。因此，可以花费数百万美元来修复一个单独的地点。详细了解污染物是如何从其源头进入周围地下水的，对于设计成功的、具有成本效益的解决方案至关重要。 有必要更好地了解现实条件下的污染情况。一种常见的情况是在污染源附近的地下存在气泡。气泡可能会随着全年地下水位的上升和下降而产生，也可能是由许多就地处理污染的清理技术造成的。气泡通常不会被考虑，但可能会对污染源的寿命、地下水使用者的风险以及污染物向地面的移动产生重大影响。例如，过去的研究表明，在有气体存在的情况下，污染物从源头转移到地下水的速度可能是前者的两倍。由四名硕士和两名博士生进行的研究将包括实验，调查净化技术应用过程中气体的形成，气体如何将污染物转移到地下水，以及污染物混合物对气体的影响。这项研究还将开发新的方法，利用计算机模型来模拟气泡和污染物之间的相互作用。 这项研究的结果将导致更准确地预测场地污染造成的风险，并改进应用清理技术的战略。这将为环境工程界提供新的见解和工具，这将使网站所有者、房地产开发商和从业者受益。

Clean water is a national priority. Millions of Canadians depend on clean groundwater as a source of drinking water. In addition, many of the tens of thousands of abandoned properties in Canada remain unused due to the contamination of soil and groundwater by industrial chemicals. Often, the most difficult sites to clean-up are those contaminated by chemicals such as petroleum fuels, solvents, dry cleaning fluids, and coal tar, which are known to present a significant risk to human health. Cleaning up these sites is a challenge due to the complexity of the subsurface, and the physical and chemical behaviour of contaminants. As a result, millions of dollars can be spent to remediate a single site. A detailed understanding of how contaminants move from their source into the surrounding groundwater is critical to engineering successful, cost-effective solutions. There is a need to better understand contamination under realistic conditions. One common condition is the presence of gas bubbles in the subsurface near contaminant sources. Gas bubbles can be created as the water table rises and falls throughout the year, or by many clean-up technologies that treat contamination in place. Gas bubbles are not typically considered, but may significantly affect the lifetime of contaminant sources, the risk to groundwater users, and the movement of contaminants toward the ground surface. For example, past work showed that contaminants may be transferred from a source to groundwater twice as fast in the presence of gas. Research conducted by four Master's and two Doctoral students will include experiments to investigate the formation of gases during the application of clean-up technologies, how gases transfer contaminants to the groundwater, and the effect of contaminant mixtures on gases. The research will also develop new approaches to simulate the interaction between the gas bubbles and contaminants using computer models. Results of this research will lead to more accurate predictions of risk due to site contamination and improved strategies for the application of clean-up technologies. This will provide new insight and tools to the environmental engineering community, which will benefit site owners, property developers, and practitioners.