Camp Lejeune, Jacksonville, North Carolina

State Coalition for Remediation of Drycleaners Site Profiles

Description
Historical activity that resulted in contamination.

The area targeted for remediation lies beneath a former dry cleaning facility (Building 25). Historical activities at the site led to subsurface releases of Dense Non-Aqueous Phase Liquids (DNAPLs) comprising primarily perchloroethylene (PCE). The dry cleaning facility had operated since the 1940s. In the 1970s, the facility began using PCE. From the 1970s through the mid-1990s, PCE was stored in a 150 gallon above ground storage tank (AST) adjacent to Building 25. In 1995, underground storage tanks (UST) were removed from the site. Although the USTs were not used for PCE storage, soils impacted with chlorinated solvents were identified. Since this discovery, multiple remediation efforts have been attempted at the site. In 1998, a DNAPL recovery system was installed north of Building 25 to remove as much DNAPL as possible from an area that was to be the subject of a Surfactant Enhanced Aquifer Remediation (SEAR) demonstration project. Approximately 30 to 60 gallons of DNAPL were removed. In 1999, the SEAR demonstration project was undertaken on the north side of Building 25. Approximately 76 gallons of DNAPL were removed. Residual surfactant remained present in treated soils.

Remediation Status: In groundwater monitoring

Contaminants
Contaminants present and the highest amount detected in both soil and groundwater.

Contaminant	Media	Concentration (ppb)
Benzene	groundwater	860 ppb
cis-1,2-Dichloroethene	groundwater	84,000 ppb
cis-1,2-Dichloroethene	soil	81,500 ppb
1,1-Dichloroethene	groundwater	1,300 ppb
Tetrachloroethene (PCE)	groundwater	64,000 ppb
Tetrachloroethene (PCE)	soil	44,352,000 ppb
Trichloroethene (TCE)	groundwater	37,000 ppb
Trichloroethene (TCE)	soil	258,000 ppb
toluene	groundwater	1,000 ppb
Vinyl Chloride	groundwater	45,000 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:		20ft bgs
Plume Size:
Average Depth to Groundwater:		7ft

Lithology and Subsurface Geology

		alternating beds of sand and silt, which turn into a silty fine sand near the aquitard Depth: 0-20ft bgs 20ft thick Conductivity: 4.1ft/day Gradient: 0.0155ft/ft
		aquitard Depth: 20ft bgs

Pathways and DNAPL Presence

Groundwater

Sediments

Soil

DNAPL Present

Remediation Scenario

Cleanup Goals:

1. Reduce risk of exposure to human and ecological receptors.
2. Removal or depletion of DNAPL.
3. Reduction of contaminant flux from the source area to surrounding groundwater.

Technologies

In Situ Zero Valent Iron

Why the technology was selected:
ZVI-Clay was compared to excavation, electrical resistive heating and dual phase extraction. ZVI-Clay was found to be less expensive to implement and potentially more effective than competing technologies.

Date implemented:
Soil mixing was conducted from February 11 to February 28, 2005. Prior to treatment, a treatability study was conducted using site soils in September 2004. After ZVI-Clay implementation, a parking lot was constructed in September 2005.

Final remediation design:
The entire volume of soil targeted for remediation was mixed in situ. To implement ZVI-Clay, a crane-mounted mixing system was used to drive a 10-foot diameter soil mixing tool. ZVI and bentonite were delivered into the subsurface via a grout, which was prepared in a batch plant. The grout was pumped through the Kelly bar and delivered into the subsurface via ports in the soil mixing tool. Mixing of the 7,000 cubic yards of soil involved mixing of 146 columns, each 10 feet in diameter and to a depth of 20 feet. Columns were overlapped to minimize pockets of untreated soil. Total materials used included approximately 200 tons of iron and 100 tons of bentonite.

Other technologies used:
ZVI-Clay. An emerging technology that combines contaminant stabilization with zero valent iron (ZVI) mediated reductive dechlorination. Conventional soil mixing techniques are used to deliver granular ZVI and clay into impacted soils. Through soil mixing, the heterogeneous subsurface is transformed into a uniform soil body. Within this body, hydraulic conductivity is reduced and contaminants are brought into intimate contact with granular ZVI. The envisioned benefit is a permanent reduction in contaminant discharge from treated soils into surrounding groundwater.

Results to date:
Soil results appear promising with an average of >90% reduction of PCE over the entire treatment area. Sampling locations for which pre- and post-treatment data are available show between 99.93% and 99.99% reduction in PCE and between 96% and 99.8% reduction in TCE at 15 feet bgs. Groundwater sampling shows reductions in PCE in the source area of between 98% and 99.6% and between 89% and 98% downgradient.

Next Steps:
The site has been redeveloped as a parking lot. No further action, other than monitoring, is anticipated.

Cost to Design and Implement:
Remedial design and treatability study: ~$130,000

Site preparation: ~$177,000

Contractor's cost for soil mixing (including mob, demob, materials and labor): ~$500,000

Oversight and monitoring through 8/07: ~$473,000

Site restoration (parking lot): ~$504,000

Costs

Cost for Assessment:
Cost for Operation and Maintenance:		None
Total Costs for Cleanup:		~$1,962,000

Lessons Learned

Once the mixing rig was mobilized, the marginal cost for treating each additional cubic yard of material was ~$46. Expanding treated area in order to minimize risk of missing a portion of the source zone is, therefore, relatively inexpensive.

Design the monitoring program to collect samples immediately after mixing to obtain more accurate initial concentrations.

Consistently collect more samples, bot soil and water, over time at the same locations.

Plan on managing stormwater through covering the treatment area or installing a sump with a small treatment system.

Over design/estimate the mixing depth, where possible, but cannot compromise any confining layers.

In mixing in areas with observed product, perform additional mixing and add additional ZVA as a safety factor.

Contacts

Chris Bozzini, CH2M Hill (chris.bozzini@ch2m.com)

Randy McElveen
NC Department of Environment & Natural Resources, Superfund Section
(randy.mcelveen@ncmail.net; 919.508.8553)

Tom Sale, Colorado State University (tsale@engr.colostate.edu, 970.491.8413)

Gary Amato, Colorado State University (gamato@engr.colostate.edu, 970.491.2765)

Site Specific References

Site 88 Building 25 Source Removal, Non-Time Critical Removal Action Report, Operable Unit No. 15, Marine Corps Base, Camp Lejeune, North Carolina, dated August 2006.

DNAPL Remediation at Camp Lejeune Using ZVI-Clay Soil Mixing, Bozzini, et al., presented at Sixth Battelle Remediation of Chlorinated and Recalcitrant Compounds conference, May 2006.

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