Open Burn/Open Detonation (OB/OD) Area Management Using Lime for Explosives Transformation and Metals Immobilization

Site Name:

Old Bombing Field, Aberdeen Proving Ground

Location:

Maryland

Period of
Operation:

During the first 12 months (December 2008 to December 2009) of the18-month monitoring period, lime was applied to waste disposal detonations via seven amendment methods.

Cleanup
Type:

Field Demonstration

Technology:
Alkaline Hydrolysis

• This demonstration used hydrated lime to manage contaminated soil at the Open Burn/Open Detonation site. The topical and detonation applications of hydrated lime to site soil accelerated the degradation of explosives contamination compounds and stabilized metals. These applications reduced the transport of the residues off site and into groundwater. Details regarding the demonstration are provided below:

  • A treatability study was performed prior to demonstration to determine a suitable lime dosing rate and to assess the longevity of the treatment and reactive pH zones. As part of the treatability study effort, a surface soil sample was collected from the vicinity of a recent munitions disposal detonation for laboratory testing.
  • A baseline site characterization study was performed to assess surface soil, sub-surface soil, pore water, groundwater, surface water, soil invertebrates in the top 6-inches of soil, and air conditions prior to lime application. Hydraulic conductivity testing was also performed using a mini disk infiltrometer.
  • The entire 9–acre demonstration site’s surface soil and subsurface soil were treated with hydrated lime to a depth of 6 inches using a tractor and drop spreader.
  • Between December 2008 and December 2009, seven lime amendment methods were assessed. These amendment methods were conducted with routine munitions waste disposal detonations. Munitions and a donor charge for each amendment scenario were placed into pits that were 3 to 4 feet deep. A 1 foot diameter cardboard tube was used to maintain access to detonate the munitions.
    • Method 1: 0.625 tons of hydrated lime was placed on top of the munitions. After detonation, the depression was backfilled with soil that was mixed with 0.625 tons of hydrated lime.
    • Method 2: Munitions were covered with 2 feet of soil and then leveled to grade. 1.25 tons of hydrated lime was then placed on top of the leveled surface in a 5-foot radius around from the cardboard tube. After detonation, backfilling material was mixed with 0.625 tons of hydrated lime.
    • Method 3: Munitions were covered with 2 feet of soil and then leveled to grade. 2.5 tons of hydrated lime was then placed on top of the leveled surface in a 5-foot radius around the cardboard tube. The hydrated lime was then covered with 2 feet of soil. After detonation, backfilling material was mixed with 0.625 tons of lime.
    • Method 4: Munitions were buried under a soil mound. 1.25 tons of hydrated lime was placed on top of the mound. After detonation, backfilling material was mixed with 1.25 tons of hydrated lime.
    • Method 5: Munitions were buried under a soil mound. 1.25 tons of hydrated lime was placed around the mound and in a 10 foot radius around the toe of the mound. After detonation, backfilling material was mixed with 2.5 tons of hydrated lime.
    • Method 6: Munitions were buried under a soil mound. 1.25 tons of hydrated lime was placed around the mound and also in a 2 foot radius around the toe of the mound. After detonation, backfilling material was mixed with 1.25 tons of hydrated lime.
    • Method 6a: Munitions were buried under a soil mound. 2.5 tons of hydrated lime was placed around the mound and also in a 2 foot radius around the toe of the mound. After detonation, backfilling material was mixed with 1.25 tons of lime.
    • Method 7: No hydrated lime was added. After detonation, backfilling material was mixed with 0.625 tons of hydrated lime.
  • After detonation, surface soil sampling was conducted to evaluate the dispersion of the hydrated lime.
  • Soil and aqueous samples were collected to test for explosive compounds and heavy metals after detonations using the various pre- and post-method lime additions. Results were compared to baseline concentrations (conditions before lime additions).
  • Personnel air monitoring and perimeter air monitoring were conducted during the demonstration.

Cleanup Authority:
Department of Defense (DoD)

Contacts:

W. Andy Martin, Deborah R. Felt, and Steven L. Larson
Environmental Laboratory
U.S. Army Engineer Research and Development Center
3909 Hall Ferry Road
Vicksburg, MS 39180-6199

Gene L. Fabian
U.S. Army Aberdeen Test Center
400 Colleran Road
Aberdeen Proving Ground, MD 21005-5059

Catherine C. Nestler
Applied Research Associates, Inc., Southern Division
119 Monument Place
Vicksburg, MS 39180

Contaminants:
Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 1,3-dinitrobenzene (1,3-DNB), Nitrobenzene (NB), Hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX), Hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX), Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 2,4,6-trinitrotoluene (TNT), 2,4/2,6-amino-dinitrotoluene (ADNT), 2,4-Dinitrotoluene (DNT), Copper, Nickel, and Zinc

Waste Source:
Open Burn/Open Detonation of waste munitions at the site is a common disposal method. These activities create the potential for explosives and heavy metal contamination of surface soils.

Type/Quantity of Media Treated:
Soil (quantity not documented)

Purpose/Significance of Application:
This demonstration evaluated the viability of using hydrated lime to accelerate the degradation of explosive compounds, to reduce the transport of explosives residues offsite and into groundwater, and to stabilize heavy metals.

Regulatory Requirements/Cleanup Goals:
For the demonstration, the performance objectives included:

  • Reduce RDX concentrations below baseline soil concentrations that were measured before the initial lime application
  • Assess the effectiveness of, and possible side effects associated with, hydrated lime application by evaluating the following:
    • The reduction of explosives concentrations in soil, soil pore water, and surface water
    • The stabilization of metals in soil
    • Baseline sampling results in comparison to post-lime application results
    • The ability to maintain a source area pH of 10.5 and a pH of 9 outside the source area
    • How transport occurs in pore water, surface water, and soil
    • Human health risks
    • Ease of use
    • Costs
Quantitative performance goals included the following:
  • Reduce RDX concentrations below the U.S. Environmental Protection Agency (EPA) Lifetime Health Advisory of 2 microgram/liter (µg/L) in the source area pore water.
  • Reduce RDX concentrations by 80% in ponding stormwater after heavy precipitation in the source area.

Results:
Performance of each method was assessed by evaluating the explosives concentrations, metals concentrations, and leaching of metals in surface soil, sub-surface/ejected soil, pore water, surface water, and groundwater. Methods 6 and 6a provided the best performance for hydrated lime dispersion.

Alkaline hydrolysis testing results of soil sampled indicated that the application of hydrated lime by methods 6 and 6a were the most effect means of dispersal. Munitions residues to surface water and groundwater were reduced to concentrations below regulatory requirements and baseline concentrations.

Cost Factors:
Two costs models are provided below. The first model is for the application of hydrated lime over the entire 9-acre demonstration site prior to conducting the demonstration, and the second is for costs associated with hydrated lime method applications.

Cost Model for Lime Application to the 9-acre Demonstration Area:

  • Treatability Study: $400
  • Baseline Characterization: No Cost Tracking
  • Material Cost
    • Lime: $1,125/acre
    • PPE: $50
  • Installation Cost: $1,225/acre
  • Soil, Groundwater, and Surface Water Monitoring (test kits): $100
  • Total Project Cost: $2,400/acre plus $500 from treatability study and monitoring


Cost Model for Lime Detonation Method Application:
  • Treatability Study: $400
  • Baseline Characterization: No Cost Tracking
  • Material Cost: $562/detonation
  • Installation Cost: $750/detonation
  • Soil, Groundwater, and Surface water Monitoring (test kits): 100
  • Total Project Cost: $1,312/detonation plus $500 treatability study and monitoring costs

Description:
The Old Bombing Field at the Aberdeen Proving Ground is an active military munitions Open Burn/Open Detonation (OB/OD) site. Due to routine munitions detonations at the site, the probability of explosives and heavy metals contamination at the site is high.

Site investigation indicated that explosives and heavy metals contamination at the site were present. A treatability study assessing the soil at the demonstration site and a baseline site characterization study for surface soil, sub-surface soil, pore water, groundwater, surface water, were conducted prior to lime application.

The entire 9-acre demonstration site’s surface soil and subsurface soil to a depth of 6-inches were treated with hydrated lime using a tractor and drop spreader. Between December 2008 and December 2009, seven hydrated lime amendment methods for detonation areas were assessed. These applications were conducted for routine munitions waste disposal detonations. Munitions and a donor charge for each amendment scenario were placed into pits that were 3 to 4 feet deep. After applying hydrated lime according to each amendment method described below, the pits were backfilled with soil. A 1 foot diameter cardboard tube was used to maintain access so the detonation charge could be applied to the munitions.

  • Method 1: 0.625 tons of hydrated lime was placed on top of the munitions. After detonation, the depression was backfilled with soil that was mixed with 0.625 tons of hydrated lime.
  • Method 2: Munitions were covered with 2 feet of soil and then leveled to grade. 1.25 tons of hydrated lime was then placed on top of the leveled surface in a 5-foot radius around the detonation area. After detonation, backfilling material was mixed with 0.625 tons of hydrated lime.
  • Method 3: Munitions were covered with 2 feet of soil and then leveled to grade. 2.5 tons of hydrated lime was then placed on top of the leveled surface in a 5-foot radius around the detonation area. The hydrated lime was then covered with 2 feet of soil. After detonation, backfilling material was mixed with 0.625 tons of lime.
  • Method 4: Munitions were buried under a soil mound. 1.25 tons of hydrated lime was placed on top of the mound. After detonation, backfilling material was mixed with 1.25 tons of lime.
  • Method 5: Munitions were buried under a soil mound. 1.25 tons of hydrated lime was placed around the mound and in a 10 foot radius around the toe of the mound. After detonation, backfilling material was mixed with 2.5 tons of hydrated lime.
  • Method 6: Munitions were buried under a soil mound. 1.25 tons of hydrated lime was placed around the mound and also in a 2 foot radius around the toe of the mound. After detonation, backfilling material was mixed with 1.25 tons of hydrated lime.
  • Method 6a: Munitions were buried under a soil mound. 2.5 tons of hydrated lime was placed around the mound and also in a 2 foot radius around the toe of the mound. After detonation, backfilling material was mixed with1.25 tons of hydrated lime.
  • Method 7: No hydrated lime was added. After detonation, backfilling material was mixed with 0.625 tons of hydrated lime.


Soil, groundwater, surface water, and air sampling was conducted after detonation to evaluate the dispersion of the lime and to test for explosive compounds and heavy metals.

The field demonstration indicated that hydrated lime is an effective treatment method to reduce explosive and heavy metal contaminant concentrations at OB/OD sites. No other technologies exist for the in situ treatment of explosives in OB/OD areas.