Long-term performance of geosynthetic barrier systems for groundwater protection

土工合成屏障系统用于大多数垃圾填埋场(占加拿大固体废物的68%)、受污染的液体泻湖和许多采矿应用(例如。堆积淋滤垫、尾矿储存设施；使用2.8亿平方米/年的土工膜)，必须最大限度地减少污染液体向地表水或地下水的流失。在历史上，该系统通常使用单一的复合衬垫，在1厘米厚的土工合成粘土衬里上覆盖1.5 mm厚(塑料)土工膜衬里的焊接板(以减少土工膜上孔洞的泄漏)，过去的研究主要集中在这种情况下。现在已经知道，单衬垫只适用于低风险项目，两个复合衬垫之间带有土工合成排水沟的双层系统通常用于大型垃圾填埋场或其他风险较高的应用场合。这些系统通常预计会限制污染物的逃逸(即。对于一些资源回收应用，从几十年到大型垃圾填埋场的几个世纪，到一些矿山废物的几千年的使用寿命。目前，关于化学相互作用或外加载荷对复合衬里泄漏的影响或双层复合衬垫系统的使用寿命几乎一无所知。这项研究代表了一个全新的调查领域，将是第一次研究这些问题。这项研究利用了最近的研究突破，采用了一种新的研究策略来考虑双层复合衬砌屏障系统中所有组件之间的相互作用，包括老化对二次排水层(土工合成排水沟)中流动的影响。就正在开发的新技术和设备而言，它是独特的、新颖的和创新的，以检查这些关键系统的性能随时间的变化，如果它们发生故障，这些系统无法修复或更换。这项工作预计将导致关键底衬的设计和施工模式的转变，这可能会导致通常使用的土工膜和排水层发生彻底变化。它将通过以下方式对人类健康和环境产生深远影响：(I)对控制单层和双层复合衬垫系统长期性能的过程提供新的基本科学见解；(Ii)基于科学的使用寿命估计；(Iii)垃圾填埋场和采矿应用屏障系统设计的新指南；以及(Iv)21世纪法规提供环境保护的科学依据。这项研究将使加拿大设计顾问、监管机构、制造商、土工合成材料安装商、设施所有者/运营商、原住民和公众受益，他们都将能够更多地依赖这些屏障系统，并提高加拿大在环境可持续发展方面的国际竞争力和声誉。这项研究将培养8名博士、2名硕士和5名本科生。**

Geosynthetic barrier systems are used in most landfills (taking 68% of Canadian solid waste), contaminated fluid lagoons, and many mining applications (eg. heap leach pads, tailings storage facilities; using 280,000,000 m2/yr of geomembrane) where loss of contaminated fluid to surface or ground water must be minimized. Historically, this system has often involved a single composite liner with welded panels of a 1.5mm thick (plastic) geomembrane liner over a 1 cm thick geosynthetic clay liner (to reduce leakage through holes in the geomembrane) and past research has focused on this case. It is now known that a single liner is only suitable for low risk projects and a double system with a geocomposite drain between two composite liners is routinely being used for large landfills or other higher risk applications. These systems are typically expected to limit contaminant escape (ie. have a service-life of) from many decades in some resource recovery applications, to centuries for large landfills, to millennia for some mine waste. At present, virtually nothing is known about the effect of chemical interaction or applied loads on leakage through composite liners or the service-life of double composite liner systems. This research represents a completely new area of investigation and will be the first to ever examine these issues. The research capitalizes on recent research breakthroughs and adopts a new research strategy for considering the interactions between all components of a double composite liner barrier system including the effects of aging on flow in a secondary drainage layer (geocomposite drain). It is unique, novel & innovative in terms of the new techniques & equipment being developed to examine the time-dependent change in the performance of these critical systems which cannot be repaired or replaced if they fail. This work is expected to result in a paradigm shift in the design and construction of critical bottom liners that will likely result in complete change in the geomembranes and drainage layers typically used. It will have a profound impact on human health and the environment by providing: (i) new fundamental scientific insights into the processes controlling long-term performance of single and double composite liner systems; (ii) science-based estimates of service-life; (iii) new guidelines for the design of barrier systems for landfills and mining applications, & (iv) a scientific basis for 21st Century regulations to provide environmental protection. The research will benefit Canadian design consultants, regulators, manufacturers, geosynthetics installers, facility owners/operators, First Nations, and the general public who will all be able to place greater reliance on these barrier systems and enhance Canada's international competitiveness and reputation for environmentally sustainable development. The research will educate 8 PhD, 2 MASc & 5 undergraduate students.**