Description
Project Site: Tooele Army Depot
TNT Washout Facility/SWMU-10
Pilot, Bench, and Full Scale Soil Corrective Measures
Client: MWH Constructors, Inc. under contract to the US Army Corps of Engineers
Contractor: Plexus Scientific Corporation.
Purpose: Reduction of TNT and RDX Concentrations in Soil
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Summary: The Tooele Army Depot (TEAD) is in
Tooele, Tooele County, Utah, 35 miles
southwest of Salt Lake City. It consists of two separate areas, the North Area and the South
Area. The North Area covers about 25,000 acres in Tooele Valley south and west of Tooele.
Since 1943, TEAD has had a fourfold mission: store ammunition, demilitarize ammunition,
rebuild military equipment, and store military equipment. In fulfilling its mission, TEAD
decommissions munitions by cutting the casings and removing and recycling the explosive
material. The casings are then rinsed with water to remove residual explosives. Between 1948
and 1965, rinse waters were discharged into the "TNT Washout Area," which covers less than 1
acre in the North Area. The Army has detected trinitrotoluene (TNT) and cyclomethylenetriamine
(RDX) in soil near the TNT Washout Area (designated as SWMU-10), threatening ground water.
About 2,500 people depend on wells within 3 miles of the site as a source of drinking water.
The Challenge: Project plans included treatment of approximately 10,000 yards of soil impacted with TNT and
RDX at concentrations as high as 2,500 and 1,000 mg/kg, respectively. In addition, soils were
required to be treated to levels below the remediation goals of 86 mg/kg TNT and 31 mg/kg
RDX.
Initial treatability and feasibility analyses suggested that conventional composting would be the
most cost-effective alternative for soil treatment, utilizing organic amendments at a rate of 70
weight percent (wt %) of the total compost mass, and treating in seven batches over the course
of twelve months' time. However, a combination of factors resulted in an increase in projected
costs. The combination of a considerable rise in fuel and shipping costs, a long haul distance to
the site from agricultural areas, and the need for relatively large quantities of compostable organic materials combined to make the originally-preferred alternative economically
unfavorable.
As a consequence of changes in project economics, Plexus Scientific recommended use of
DARAMENDR as an alternate form of treatment to reduce costs and make it possible for the
project to be completed within budget. MWH and the Army Corps accepted this alternative
following the completion of pilot-scale soil treatment that met the site remediation goals.
Field Work: Pilot-scale soil treatment with Adventus' DARAMEND was conducted at TEAD SWMU-10 to
assess field efficacy of DARAMEND for composting site soils for treatment of TNT and RDX.
Both the pilot and a concurrent bench-scale treatment study effectively demonstrated that the
DARAMEND technology effectively treated site
soils to levels below the remediation goals of 86
mg/kg TNT and 31 mg/kg RDX. Based on these
results, the Army implemented Full-Scale
DARAMEND treatment of the SWMU-10 soils.
For the full-scale treatment, soil was treated in
large batches (about 3,000 cubic yards each) in
a large sprung structure. In an effort to reduce
treatment time and the associated labor and
equipment costs, DARAMEND was added in a
single dose of 3.5 wt% to soil mass upon
initiating treatment of each batch, rather than through smaller incremental additions at the start
of each treatment cycle. Given the very dry arid soils and limited water supply, it took
approximately a week to add sufficient water to the soil to achieve adequate moisture content
for treatment.
The Result: Plexus Scientific effectively treated soils to
remediation goals in a single application cycle.
Results for the first batch of soil are typical of
subsequent batches, and are shown below. Note
that additional reductions continued to occur with
additional tilling and soil resting, but without the
addition of more DARAMEND. Treatment of the
three batches was completed in approximately
five months, considerably less than the original estimate of one year with conventional composting.
The Conclusion: DARAMEND was highly effective in the treatment of TNT and RDX in soil, providing a safe,
effective, reliable and more economical alternative to conventional composting. Moreover, at a
material cost of $62/yd3, the DARAMEND approach provided great economic value to the
clients, saving them both time and money.
Other Companies:
Richard Valdez, MWH Constructors, richard.r.valdez@mwhglobal.com, 505.715.3200
MWH
http://www.mwhglobal.com/
Matt Fedowitz, Plexus Scientific Corporation, mfedowitz@plexsci.com, 410-715-3865 x122
Plexus Scientific http://www.plexsci.com/
To discuss the technology or request a free estimate, please
contact Adventus.
Companies On This Project
ADVENTUS GROUP
