OWNER:
Kerr McGee Chemical Corporation
Mobile Facility, Theodore, Alabama

ENGINEER:
Thompson Engineering Testing, Inc.
3707 Cottage Hill Road
Mobile, Alabama 36606

In order to increase their on-site storage capacity for the iron oxide by-product produced by the plant, Kerr-McGee built a twenty-seven acre iron oxide containment pond in 1990. The containment dike was constructed to a height of 22.5 feet with a 15-foot wide crest and 3:1 side slopes for a total length of 3,540 feet. The site was underlain by soft to very soft marine clays extending from elevation +20 to elevation -40. Calculations were made to determine the required construction rate for the dike if the target completion date was met. Using this rate of construction, effective stress stability analyses were performed to ascertain the level of reinforcing required to achieve the target minimum factor of safety at the end of dike construction. Four layers of uniaxial geogrids were used to achieve this minimum factor of safety. Instrumentation for the project consisted of settlement plates, slope inclinometers and piezometers that were monitored during construction. The project was successfully completed on schedule in 1990.