Opal Group Inc.

Ash Pond Closure

Confidential Client

Seaford, DE

Opal was retained by a nylon manufacturing facility to perform a complex $1.1 million excavation of 80,000 cubic yards (yd3) of wet fly ash from a 15-ft deep, 575-ft long x 285-ft wide storage impoundment, dry the ash, and place the ash in thin, compacted lifts in a six-acre on-site ash disposal landfill. The ash was a minus 300-mesh material, discharged to the impoundment as slurry and further saturated by groundwater flowing into the pond. Following installation of dewatering sumps to maintain a downward gradient within the ash, the material was removed using long-stick excavators. The excavators cast the saturated materials on the ash surface to the rear and stacked the material in windrows to enable the material to drain. After a 24- to 48-hour period, the ash was sufficiently dry to transport to the landfill, spread, rework to further dry and compact. Although this procedure required double-handling of the material, it avoided the use of solidification agents or other admixtures which would have increased the volume of waste material and increased the transportation and overall costs of ash disposal. Surface water control within both the impoundment and landfill was particularly critical, aggravated by abnormal precipitation events during the course of the work. Extensive geotechnical repairs were also performed on the surrounding 20-foot high storage pond containment dikes.


Services/Descriptions/Materials: Demolition, RCRA, Sludge, Solidification, Fly Ash