A framework for assessing risk reduction due to DNAPL mass removal from low-permeability soils
A framework for assessing risk reduction due to DNAPL mass removal from low-permeability soils
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DOI：
10.1111/j.1745-6584.1997.tb00066.x
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发表时间：
1997-01-01
期刊：
影响因子：
2.6
通讯作者：
McWhorter, DB
中科院分区：
文献类型：
--
作者：
Freeze, RA;McWhorter, DB
许多新兴的补救技术旨在从DNAPL站点的污染源区域去除污染物质量以响应监管要求，但受监管社区经常担心，大规模清除是否真的降低了风险，或者实现的小风险降低是否值得付出高昂的成本。本文提出了一个建议的框架，用于量化在浅层、饱和、低渗透介质中，随着DNAPL源区的质量被移除，风险降低的程度。风险的定义是在源区下面的含水层的合规井处达到替代浓度限制(ACL)，根据下坡供水井的致癌健康风险特征反算ACL，源区质量清除效率在很大程度上取决于介质(裂缝、基质)和相(含水、吸附、NAPL)之间的质量分配。由于现有技术性能数据的不确定性，本白皮书的范围仅限于开发通用技术的框架，而不是针对个别技术进行具体的风险降低计算。尽管这项工作的性质是定性的，但结果表明，要通过有限持续时间的技术应用实现显著的长期风险降低，需要非常高的总质量清除效率。这篇论文并不是主张在受污染的地点不采取行动，而是为Cherry等人的结论提供了支持。(1992)，当前补救措施的主要目标应该是通过遏制减少短期风险，目的是将非常适合未来应用于具有改进的大规模清除能力的新兴技术的场地条件传给后代。
Many emerging remediation technologies are designed to remove contaminant mass from source zones at DNAPL sites in response to regulatory requirements, There is often concern in the regulated community as to whether mass removal actually reduces risk, or whether the small risk reductions achieved warrant the large costs incurred. This paper sets out a proposed framework for quantifying the degree to which risk is reduced as mass is removed from DNAPL source areas in shallow, saturated, low-permeability media. Risk is defined in terms of meeting an alternate concentration limit (ACL) at a compliance well in an aquifer underlying the source zone, The ACL is back-calculated from a carcinogenic health-risk characterization at a downgradient water-supply well, Source-zone mass-removal efficiencies are heavily dependent on the distribution of mass between media (fractures, matrix) and phase (aqueous, sorbed, NAPL). Due to the uncertainties in currently available technology performance data, the scope of the paper is limited to developing a framework for generic technologies rather than making specific risk-reduction calculations for individual technologies. Despite the qualitative nature of the exercise, results imply that very high total mass-removal efficiencies are required to achieve significant long-term risk reduction with technology applications of finite duration. This paper is not an argument for no action at contaminated sites, Rather, it provides support for the conclusions of Cherry et al. (1992) that the primary goal of current remediation should be short-term risk reduction through containment, with the aim to pass on to future generations site conditions that are well-suited to the future applications of emerging technologies with improved mass-removal capabilities.