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Yorktown
Naval Weapons Station
Yorktown, Virginia, USA
Project
Full-Scale Bioremediation of
Organic Explosives and Chlorinated Solvents in
Soil & Sediment
Summary
Soils and sediments (~5,000 yd3) impacted with
organic explosive compounds and chlorinated
solvents were treated ex-situ in a covered land
treatment unit containing approximately 1,200
yd3. In the first four batches, the initial mean
TNT concentration was generally near 10,000 mg/kg
and was reduced by greater than 99.9% following
treatment. Similarly, the mean RDX and DNT
concentrations for the first four batches were
reduced by over 98.4%.
The Challenge
In total, an estimated 9,000 yd3 of soil is to be
treated at Yorktown Naval Weapons Station.
Remedial goals for TNT, RDX, and DNT are 14mg/kg,
5mg/kg, and 44 mg/kg, respectively. To reach
these goals, removal efficiencies of over 99%
must be achieved.
The Solution
DARAMEND®, a proprietary organic
bioremediation product, was applied ex-situ on
four 1,200 ton batches of soil heavily impacted
with organic explosives. DARAMEND® was
applied to the soil surface and incorporated to a
depth of 2 feet with simple soil mixing
equipment. Mixing also aerated and homogenized
the soil. Water was applied to increase soil
moisture content. These steps are repeated
through each treatment cycle (usually 7 –
10 days).
Subsequently, a decision was made to employ an
innovative treatment application method on
additional, less heavily impacted soils at the
site. This pre-treatment step, applied in place
at the excavation site, would reduce the organic
explosive concentrations prior to moving sediment
to the bioremediation treatment cell. This would
reduce treatment time for each batch.
Pretreatment is expected to substantially reduce
the volume of soil to be moved to the treatment
cell, as concentrations of organic explosives in
these lightly contaminated soils may be reduced
to levels below the remedial standards during
pre-treatment.
The Result
DARAMEND® bioremediation technology supported
efficient removal of all target compounds in soil
and sediment at Yorktown Naval Weapons Station to
levels well below the cleanup criteria for each
of the first four batches.
• TNT concentrations were reduced by 99.9%
(15,359 mg/kg to below 14 mg/kg in fourth
treatment batch)
• RDX concentrations were reduced by 99.9%
(1,090 mg/kg to 1.6 mg/kg in third treatment
batch)
• Total amino-DNT concentration was reduced
by 98.7% (1,002 mg/kg to 13 mg/kg in first
treatment batch)
To our knowledge, this is the only case in which
soil containing organic explosives at more than
10,000 mg/kg has been successfully treated
without dilution.
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