Paper_Successful Installation of a Vertical Hydraulic Barrier at a CCR Impoundment During In Place Closure.pdf

Jim Edwards, Forgen
Sylvain Payne-Gagnon, Forgen

Description

Successful Installation of a Vertical Hydraulic Barrier at a CCR Impoundment During In-Place Closure Authors Mr. Jim Edwards - United States - Forgen Mr. Sylvain Payne-Gagnon - United States - Forgen Abstract Forgen was contracted to install a cut-off wall as part of a Vertical Hydraulic Barrier System that will encircle the ash consolidation area for a CCR impoundment undergoing closure in-place. Forgen’s scope of work included mix design, installation of a test section, sampling of the hardened test section, and installation of the cutoff wall. The hardened backfill was required to achieves: • Hydraulic Conductivity ≤ 1 x 10-7 cm/sec at 28 days • Unconfined compressive strength @ 28 days ≥ 30 psi and ≤ 200 psi To achieve these specifications, Forgen developed a slag-cement-bentonite (SCB) grout backfill during mix design testing. We mobilized to the site and installed a small test section using full-scale equipment. Once sufficiently cured, Forgen performed continuous vertical and angular coring through the hardened SCB backfill to verify the homogeneity of the mix, the 3-foot bedrock (chalk) key, and the overlap of panels. When sampling results demonstrated that the test section met the specifications, Forgen remobilized and proceeded with the installation of the main SCB cutoff wall, using a powerful CAT 374 hydraulic excavator equipped with a GPS monitoring system. The installed cutoff wall hydraulically isolated the consolidated ash within the CCR closure from the underlying groundwater.

 
May 15th, 9:00 AM May 15th, 9:30 AM

Paper_Successful Installation of a Vertical Hydraulic Barrier at a CCR Impoundment During In Place Closure.pdf

Grand Rapids, Michigan

Successful Installation of a Vertical Hydraulic Barrier at a CCR Impoundment During In-Place Closure Authors Mr. Jim Edwards - United States - Forgen Mr. Sylvain Payne-Gagnon - United States - Forgen Abstract Forgen was contracted to install a cut-off wall as part of a Vertical Hydraulic Barrier System that will encircle the ash consolidation area for a CCR impoundment undergoing closure in-place. Forgen’s scope of work included mix design, installation of a test section, sampling of the hardened test section, and installation of the cutoff wall. The hardened backfill was required to achieves: • Hydraulic Conductivity ≤ 1 x 10-7 cm/sec at 28 days • Unconfined compressive strength @ 28 days ≥ 30 psi and ≤ 200 psi To achieve these specifications, Forgen developed a slag-cement-bentonite (SCB) grout backfill during mix design testing. We mobilized to the site and installed a small test section using full-scale equipment. Once sufficiently cured, Forgen performed continuous vertical and angular coring through the hardened SCB backfill to verify the homogeneity of the mix, the 3-foot bedrock (chalk) key, and the overlap of panels. When sampling results demonstrated that the test section met the specifications, Forgen remobilized and proceeded with the installation of the main SCB cutoff wall, using a powerful CAT 374 hydraulic excavator equipped with a GPS monitoring system. The installed cutoff wall hydraulically isolated the consolidated ash within the CCR closure from the underlying groundwater.