Collaborative Research: Air-Flow Mechanisms During Insitu Air-Sparging Operations

美国有超过3亿英亩的土地受到地下水污染的严重威胁。还有更多的土地受到地下水污染，尽管被认为不严重，但威胁着当地的地下水质量和环境健康。目前，使用现有的修复方法清理受污染地下水的成本超过了美国每年的国民生产总值。因此，尽管污染地下水原位修复技术的设计最近取得了进展，但仍需要进行研究，使这些技术更具成本效益和效率。原位空气喷射（IAS）是一种修复技术，在清除受挥发性有机化合物（VOCs）污染的含水层方面取得了成功，如石油碳氢化合物。事实上，在美国，原位空气喷射法被认为是修复碳氢化合物污染场地最广泛使用的技术。尽管如此，IAS设计在实践中仍然主要是经验主义的，并且基于从单个喷雾井周围的中试规模测试中获得的信息。研究界已经开发了IAS绩效的预测模型。然而，这些模型在设计实践中的使用受到其复杂性的限制，更值得注意的是，它们使用的土壤参数在实践中通常不会测量。此外，许多这些模型只考虑单个喷雾点，而IAS系统设计有多个喷雾点，专门用于产生重叠的空气羽流。建议的工作将开发一个可靠和实用的模型来预测多点喷射产生的气流模式，以改进当前IAS系统的设计和优化。最终的模型将基于地质离心机测试和浸入法的结合，从而能够直接可视化模拟现场毛细管和流体压力下的空气羽流发展。先前的工作产生了一个轴对称模型，该模型可以根据实际测量的典型输入参数预测均匀介质中单个喷雾点以上的气流模式。原始模型的扩展将能够预测非均匀介质中多个喷雾点以上的三维空气羽流发展。研究人员将使用来自中试规模测试的现场数据和实际的IAS操作来验证该模型。这项工作将对IAS系统的未来设计产生相当广泛的影响。改善补救技术的有效应用，包括IAS，将对未来的公众健康和环境健康产生直接的好处。释放先前被污染的土地进行再利用也为国家提供了经济和社会效益。研究结果将通过我们在项目第三年举办的专业发展研讨会进行传播。为了鼓励实践人员参加，我们将每次研讨会限制为一天。这些研讨会将按成本费收费。他们将讨论在IAS期间影响气流的因素、IAS设计考虑因素、试点测试和监测要求。他们还将介绍新模式，并为其在实践中的使用提供指导。

There are over 300 million acres of land in the United States for which underlying groundwater contamination is labeled a serious concern. There are many more acres for which underlying groundwater contamination, although not considered serious, threatens local groundwater quality and environmental health. The current cost of cleaning up contaminated groundwater using existing approaches to remediation is greater than the annual US Gross National Product. Thus, despite recent advances in the design of technologies for the insitu remediation of contaminated groundwater, research is still required that enables these technologies to become more cost effective and efficient. Insitu Air Sparging (IAS) is one remediation technology that has documented success for the cleanup of aquifers contaminated with Volatile Organic Compounds (VOCs), such as petroleum hydrocarbons. In fact, insitu air sparging is now thought to be the most widely used technology in the US for the remediation of hydrocarbon contaminated sites. Despite this, IAS design in practice remains largely empirical and based on information obtained from pilot scale tests involving observations surrounding a single sparge well. The research community has developed predictive models for IAS performance. However, the use of these models for design practice has been limited by their complexity and, more notably, their use of soil parameters that are not typically measured in practice. In addition, many of these models only consider a single sparge point, whereas IAS systems are engineered with multiple sparge points specifically to generate overlapping air-plumes. The proposed work will develop a reliable, and practical, model to predict the air-flow patterns generated by multiplepoint sparging to improve the current design and optimization of IAS systems. The resulting model will be based on combined geo-centrifuge testing and the immersion method to enable direct visualization of air-plume development under capillary and fluid pressures that mimicked those in the field. Previous work resulted in an axi-symmetrical model that can predict air-flow patterns above a single sparge point in a homogeneous medium based upon input parameters typically measured in practice. The extension of the original model will enable predictions of three-dimensional air plume development above multiple sparge points in a heterogeneous medium. The researchers will validate the model using field data from pilot scale tests, and actual IAS operations. This work will have considerable broad impact on the future design of IAS systems. Improvements in the effective application of remediation technologies, including IAS, will have direct benefit on future public and environmental health. The release of prior contaminated land for re-use also provides economic and social benefit to the country. The results will be disseminated through professional development seminars that we will run in Year 3 of the project. To encourage attendance by those in practice, we will limit each seminar to one day. The seminars will be run at cost. They will discuss the factors influencing air-flow during IAS, IAS design considerations, pilot testing, and monitoring requirements. They will also introduce the new model and provide guidance on its use in practice.