SGER: Forensic Analysis of a Final Cover Relying on a Clay Barrier

SGER：依赖粘土屏障的最终覆盖物的法医分析

• 批准号: 0437306
• 负责人: Craig Benson
• 金额: $ 2.8万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-15 至 2005-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0437306&HistoricalAwards=false
• 关键词: SGER; Forensic; Analysis; Final; Cover

Final covers that rely on a compacted clay barrier layer as the primary impediment to percolation are commonly used in the US for waste containment and isolation of contaminated materials. The cover generally consists of a layer of compacted clay 450-900 mm thick overlain by an erosion layer that is 150 mm to 900 mm thick. The saturated hydraulic conductivity of the clay generally is required to be less than 10 -7 cm/s, which corresponds to a maximum percolation rate of 32 mm/yr under conditions of continuous gravity drainage. Thousands of these covers have been constructed in the US. However, there is growing concern that these covers are unlikely to perform as intended over the long-term due to the destructive effects of desiccation and frost action. Field data from several sites suggest that these processes are resulting in percolation rates that are much higher than intended (hundreds of mm per yr), but detailed investigations have not yet been conducted to show that the high percolation rates are definitively tied to morphological changes in the clay barrier layer. In the proposed study, a forensic investigation of the cover will be conducted, the result being a unique and novel data set describing the effects of weathering on the fabric, hydrologic properties, and field performance of a clay barrier in a cover. A series of field and laboratory tests will be conducted. Field hydraulic conductivity tests that permeate different volumes of soil will be conducted directly on the barrier layer and large undisturbed samples of the barrier layer will be retrieved for laboratory hydraulic conductivity testing. The pathways conducting flow will be marked with dye added to the permeant water used for the hydraulic conductivity tests. After permeation, transects will be excavated in the cover to study the aperture, length, and spacing of the dye-stained cracks. A similar examination will be conducted after permeating the laboratory specimens.The study has economic, environmental, and societal impacts. Economic and environmental impacts will be realized by providing a thorough evaluation of the effectiveness of the most common remedy used in Superfund projects. The results of this study may show that other cover technologies are likely to be more cost effective and environmentally protective over the long-term than covers relying on a compacted clay barrier. Societal impacts will be realized through the diversity efforts of the PI in undergraduate and graduate studies.

在美国通常使用依赖压实的粘土屏障层作为渗透的主要障碍的最终覆盖物用于废物遏制和隔离污染材料。盖子通常由压实的粘土层组成450-900毫米厚的覆盖，其侵蚀层的厚度为150毫米至900毫米。粘土的饱和水力电导率通常需要小于10 -7 cm/s，在连续重力排水条件下，对应于32 mm/yr的最大渗透率。这些封面中成千上万是在美国建造的。但是，由于干燥和霜冻作用的破坏性影响，这些覆盖物越来越担心不太可能按照长期的意图执行。来自多个站点的现场数据表明，这些过程导致渗透率比预期的要高得多（每年数百个毫米），但尚未进行详细的研究以表明高渗透率与粘土屏障层的形态变化明确相关。在拟议的研究中，将对盖子进行法医研究，结果是一个独特而新颖的数据集，描述了风化对织物的影响，水文特性以及盖上粘土屏障的现场性能。将进行一系列现场和实验室测试。将直接在屏障层上进行渗透到不同土壤的场液压电导率测试，并将检索大型不受干扰的屏障样品，以进行实验室水力电导率测试。导电流的途径将用染料添加到用于液压电导率测试的恒温水中。渗透后，将在覆盖层中发掘样品，以研究染料染色裂纹的孔径，长度和间距。渗透到实验室标本后将进行类似的检查。该研究具有经济，环境和社会影响。通过对超级基金项目中最常见的补救措施的有效性进行彻底评估，将实现经济和环境的影响。这项研究的结果可能表明，与依靠紧凑型粘土屏障相比，其他覆盖技术在长期内可能更具成本效益和环境保护性。通过PI在本科和研究生研究中的多样性努力，将实现社会影响。