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Naval Construction Battalion Center, Gulfport,
Mississippi
S/S Treatment of Dioxin-Contaminated Sediment
 Solidification/Stabilization
(S/S) is being used to treat dioxin-contaminated sediment at the
Naval Construction Battalion Center (NCBC) in Gulfport, MS. The
treated material will form the foundation for a heavy equipment
parking lot.
NCBC is an active base that covers 1,100 acres in Gulfport. Between
1968 and 1977, an herbicide called “Agent Orange” was
stored on the base. This dioxin-containing herbicide was used as
a defoliant during the Vietnam War. Approximately 850,000 gallons
of the herbicide were stored on a 30-acre area of the base in 55
gallon drums. Spills and leaks of the herbicide migrated from the
storage area contaminating a network of drainage ditches and wetlands
on and off the base.
S/S treatment involves mixing binding reagents like portland cement,
into contaminated material. The treatment protects human health
and the environment by immobilizing hazardous constituents within
the treated material. The remedial action at NCBC includes (a) removing
and transporting approximately 75,000 tons of contaminated sediment
from wetland and ditches to a treatment/disposal area, (b) treating
sediment using cement-based S/S to a 50 psi geotechnical performance
standard, (c) treating an upper layer to a 500 psi standard for
use as a base for pavement (d) capping the treated material with
roller compacted concrete pavement (RCCP) for use as a parking lot
for heavy equipment.
 A
road reclaimer is being used to mix binding reagents into the contaminated
sediment. First the sediment is transported to an 11-acre treatment/disposal
area. The sediment is placed down in lifts (layers). The road reclaimer
mixes S/S binding reagent into each lift of material to be treated.
For the 50 psi specified material, a 5%-7% cement addition rate
is being used. Incinerator ash is also being used as a binding reagent
in this layer. The ash is from incineration processes performed
in the early 1980’s and stored at the NCBC. Successive lifts
placed on top of each other are treated by road reclaimer. The final
thickness of material treated to 50 psi varies between 6 inches
to 5 feet based on the dome-shaped contour of the treatment/disposal/parking
area. Bench-scale studies are currently underway to determine the
mix design for the 500 psi specified material. This layer is planned
to be 6 inches thick.
A 12-inch thick roller-compacted concrete pavement (RCCP) will
be constructed on top of the entire 11-acre area. RCCP is a less
expensive than conventional cast concrete pavement since the paving
method does not use formwork. Instead, paving rollers are used to
shape and consolidate the dense ‘no-slump” concrete
mixture. RCCP creates an industrial-strength concrete pavement that
as been used at a wide range of facilities including composting
facilities, automobile manufacturing new car parking, port facilities,
and heavy battle tank stands.
This remedial action was underway before Hurricane Katrina hit
the region and will resume as soon as possible.
PDF
of the complete case study.
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