An innovative cover system to close an ash/sludge impoundment FIGURE 2 Traditional final cover system (cross-section) (Based on RCRA Subtitle D) An example of a cross section of a traditional final cover system is shown in Figure 2. This traditional approach presented various challenges for the site conditions for these closures, resulting in investigating alternative methods that could reduce or eliminate some of the challenges. The most compelling challenge was the abundance of water in the waste pile. To dewater the sites to the point where consolidation could be achieved, and subsequent fill and grade activities could commence, would likely take one to two years. This process would also risk being protracted through exposure of the waste sites to continued precipitation. The projects are in a region that receives almost 50 inches (127 cm) of average annual precipitation. During this time, the ongoing conflict with the local community over the odor emissions continued. In addition, the process of adding the necessary soil fill to achieve desired grade could require thousands of truck trips, equipment activity and associated construction disturbance for a few years. These activities would likely further strain relations with the local community. In an effort to qualify solutions, the project team identified and prioritized the following objectives for the closures: 1. Eliminate odor as quickly as possible 2. Decrease overall construction schedule 3. Minimize life-cycle cost (construction and maintenance) With the primary objectives identified and prioritized, the project team chose an alternative solution that satisfied all criteria: a tufted geosynthetic final cover system (TG-FCS). Overview of the TG-FCS FIGURE 3 Tufted geosynthetic final cover system (cross section) 34 Geosynthetics | August September 2019 The TG-FCS is comprised of three primary components: a structured geomembrane, an engineered synthetic turf