OWNER:
Mississippi Power Company
Gulfport, Mississippi

ENGINEER:
Southern Company Services
Birmingham, Alabama

CONTRACTOR:
T. L. James Industrial Constructors, Inc.
P. O. Box 77760
Baton Rouge, LA 70879-7760

Mississippi Power Company proposed to upgrade their approximate 150-acre ash pond by increasing the height of the perimeter dikes by about 8 feet. The existing dikes had been initially constructed in a marsh area and had been raised several times previously. Slope stability of the existing dikes, which were about 20 feet to 30 feet in height, were determined to be marginally stable. A cement-bentonite slurry wall was designed to extend through the existing dike and penetrate the underlying soft organic soils. The slurry wall both increased stability and provided a seepage cutoff. Due to constraints at the existing dike toe, the dike raise was designed for the inboard side. This required that the new dike be constructed partially over the soft slurried ash. Uniaxial geogrids were used to increase slope stability of the new dike, which would be constructed in two phases. The first phase of the new dike construction was completed in 1995 on time and within budget. Phase II construction will be completed when the added capacity is needed.