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The C-17 Hangar project at McGuire Air Force Base (MAFB) was a rapid-turnaround project that began when solvent contaminants were discovered in the excavated footprint of a new aircraft hangar. All work was conducted during 2003, including planning, investigation, and the start of remediation. The project was designed as an Interim Remedial Investigation (IRI) to be immediately followed by an Interim Remedial Action (IRA). It was essential that the project be completed (including planning, the IRI, and the IRA) within 5 months so that construction of the hangar could be restarted. Systematic planning and pre-mobilization for field activities were initiated for a 3-week period, followed by field activities for the next 3 weeks. A report was submitted 2 weeks after the completion of field activities to allow initiation of remedial activities within the required timeframe.
All three aspects of the Triad and a high-resolution site characterization (HRSC) approach were used to achieve project success:
Contaminants of concern included chlorinated solvents and non-chlorinated volatile organic compounds (VOCs) associated with Stoddard solvent, although the site was also screened for other contaminants (semivolatile organic compounds [SVOCs] and metals) not discussed in this Profile. Stoddard solvent is an organic solvent derived from the refining of crude oil. It is a mixture of distilled alkanes, cycloalkanes (naphthenes), and aromatic compounds. Stoddard solvent is used as a paint thinner, as a solvent in some types of photocopier toners, in some types of printing inks, in some adhesives, as a dry cleaning solvent, and as a general cleaner and degreaser (its probable use at the C-17 site).
Over 4,500 analytical results were collected for soil and groundwater using field-based techniques, primarily direct push technology (DPT) with direct-sensing tools like cone penetrometer testing (CPT), membrane interface probe (MIP), fuel fluorescence detector probe (FFD), and direct sampling ion trap mass spectrometry (DSITMS). The field results were corroborated by other data such as geologic logging and off-site laboratory analyses of soil and groundwater samples. The results of the investigation and risk assessment led to the immediate excavation of approximately 500 cubic yards of soil from the unsaturated zone. In accordance with the project DWS, the field activities were adapted in real-time to develop a data set for evaluating natural attenuation when biodegradation mechanisms were found to be active. The results allowed state and federal regulators to give conditional approval for an IRA plan involving natural attenuation; 12 natural attenuation monitoring wells were installed shortly thereafter. The construction of the C-17 Hangar was completed on schedule for the arrival of C-17 aircraft.
| Site Name | McGuire Air Force Base, C-17 Hangar Area and Building 2227 |
| Location | New Hanover Township, NJ |
| Site Types |
|
| Site Regulatory ID |
CERCLIS ID# NJ0570024018/USAF IRP Site SS-24 |
| Project Lead Organization | McGuire Air Force Base Environmental Flight |
| Project Lead Type |
U.S. Air Force Lead |
| Regulatory Lead Program |
Superfund Remedial |
| Triad Project Status | Field Program Completed |
| Reuse Objective Identified |
Yes |
| Proposed Reuse: |
Commercial/Industrial (military aircraft hangar) |
MAFB is an active facility that occupies more than 3,500 acres in a rural area of Burlington County, New Jersey. The base is bordered to the north by the community of Wrightstown, and to the east, south, and west by the U.S. Army's Fort Dix military installation. MAFB is located within the boundaries of the Pinelands National Reserve. The Pinelands are classified as Federal Land Designated for the Protection of Natural Ecosystems. The primary source for both community and private drinking water supplies in the vicinity of the site is groundwater obtained from the various aquifers comprising the Atlantic Coastal Plain. There are two major drainage divides on site, and several streams to which surface runoff is directed. An extensive system of wetlands is found along both major surface water drainage pathways. Past activities at MAFB in support of operational missions created a number of waste sources of potential environmental concern for these potential exposure pathways.
The C-17 Hangar project was part of an overall military construction (MILCON) project essential to the MAFB mission to house the C-17 aircraft. The 2.8-acre hangar was constructed at a location formerly occupied by several buildings, which had been demolished. During construction, groundwater contamination was discovered in January 2003 at concentrations high enough to require a stop-work order. The Air Force set a schedule that required the completion of planning, an interim investigation, and the IRA by the end of June 2003. This schedule would permit construction activities to resume in July 2003 and be completed by July 2004 in time for arrival of the C-17 aircraft.
The high-resolution, real-time data from the Triad-based IRI identified sources areas and verified a complete exposure pathway from soil to groundwater for contaminants associated with chlorinated solvents and Stoddard solvent. Maximum concentrations of chlorinated solvents were generally below 2,000 micrograms per liter (µg/L). Maximum concentrations of other VOCs were generally below 20 µg/L. 1,1-Dichloroethene, a breakdown product of the chlorinated solvents released at the site, was the most widely-distributed contaminant. (This observation supported the finding that natural biodegradation of the solvents was occurring).
Based on the data from the 3-week Triad investigation, the project team concluded that:
The rapid investigation and quality of the data obtained allowed the IRA to begin immediately. Remedial activities included the removal of 500 cubic yards of soil and the installation of 12 monitoring wells to assess ongoing natural attenuation. The results of the IRI/IRA were incorporated into a broader Remedial Investigation (RI) of the SS-24 study area that continued after the C-17 Hangar was constructed.
The MAFB C-17 Aircraft Hangar military construction (MILCON) project was a $28-million, nationally important defense construction project that was prioritized for completion by 2004. The project was also essential to the MAFB mission. When a solvent plume and a potential source area were discovered in the 5-acre footprint of the project in March 2003, the construction schedule was threatened. A Triad-based HRSC approach was used to meet the Air Force's objectives of rapid and complete delineation of the contamination and implementation of an, IRA, so that the construction schedule could be maintained. The Triad framework met these objectives by supporting implementation of the IRA in only a few months instead of the conventional timeframe of several years.
The project highlights what can be accomplished with a motivated landowner and cooperation from regulatory agencies. The Air Force was able to quickly resolve a significant environmental contamination problem that threatened a mission-critical MILCON project at the base. The core technical team (CTT) and stakeholders recognized that the Triad-based HRSC collected far more data about the contaminant plume than conventional field programs of similar duration that had been implemented at other MAFB sites.
The Triad-based HRSC approach allowed a newly discovered site to be taken from the planning stages through investigation and remedial action, to operation and monitoring in less than 5 months. Costs were also reduced, and a two-pronged remedial solution was implemented. Soil contamination was delineated and removed with a high level of confidence based on a diverse, high-density data set collected during the investigation. Natural attenuation monitoring was initiated after data collected during the investigation supported this option, with the rapid concurrence of regulators. Specific cost and schedule benefits are further discussed below.
Cost savings have been estimated as greater than 50% by the Air Force. Costs associated with the investigation and remedial actions have totaled $1.2 million during government fiscal years 2003 through 2007, and the Air Force has estimated that $1.34 million in savings was realized by using the Triad program.
Time savings were estimated as 18 to 24 months (three to five times the total length of the 5-month Triad program).
The CTT established the following specific project objectives:
The regulatory agencies were included in the planning activities from the earliest stages. The CTT and agencies agreed to contaminant action levels and to the decision logic that would guide the investigative and remedial activities.
The initial conceptual site model (CSM) was based on:
The initial CSM identified the most likely source(s) of subsurface chlorinated solvent contamination as one or more of the following:
Near-surface groundwater transport and large diameter storm water lines were identified as the most likely pathways for transport of subsurface contaminants from the site. Surface water associated with the storm water lines and groundwater discharge points was identified as the most likely receptor of any contamination leaving the site. Based on the initial CSM, initial field investigation maps were developed as a starting point to apply the judgment-based sampling and analysis approach outlined in the DWP.
The project work plan included sampling contingencies based on decision logic. Data collection was sequenced to efficiently determine the site hydrogeology and the magnitude, nature, and extent of the contamination. Experienced members of the CTT were present in the field to guide the investigation activities. The CSM was updated frequently using data from a variety of real-time data collection technologies. All site uncertainties were investigated and resolved during the course of the fieldwork to the satisfaction of the CTT and stakeholders.
Decision logic was used to refine each investigative step based on the results of the previous step. Locations for sample collection during focused sampling were based on the results of the site reconnaissance CPT investigation. Data gaps were identified based on the focused sampling results, and were addressed using the appropriate tools. Decision-making was largely "judgment-based" for the project (that is, based on the professional judgment and experience of the CTT), as opposed to based on quantitative or statistical data evaluations.
Decision logic was also used to assess whether (1) natural attenuation was a viable remedial strategy and (2) a targeted removal was necessary. Based on site data, soil was removed, and natural attenuation was found to be a valid strategy. Examples of the decision logic used by the field team are presented here (1, 2).
Real-time measurement technologies included:
Collaborative data from fixed-base laboratories included 60 soil and groundwater samples to assess and manage analytical uncertainty from the field methods. An onsite geologist logged 20 continuous soil cores for comparison to stratigraphic maps generated from CPT soundings.
TQRS not prepared
Collaborative data sets from off-site laboratories, collected in accordance with Air Force Center of Environmental Excellence (AFCEE) quality assurance/quality control (QA/QC) requirements, verified the sufficiency of the Triad data set for decision-making during the IRI/IRA program. These collaborative data have included post-excavation samples after the soil removal program, as well as groundwater monitoring data from wells subsequently installed during the monitored natural attenuation (MNA) remedy. The quality of the IRI/IRA data will be further documented as part of the broader RI report for the SS-24 study area; this study was still in progress at the time this Profile was prepared.
The CTT used a Trimble Pro XRS global positioning system (GPS) to collect and maintain geographical information system (GIS) data. Sample collection locations were surveyed using GPS with sub-meter accuracy.
Site stakeholders also used an on-site Dell workstation to run ArcGIS, Groundwater Modeling System (GMS), and other data management and data visualization tools for real-time data management and decision-making. Data management, communication, and review were coordinated from an on-site project "War Room" which served as a center for collaborative decision-making by the CTT in conjunction with on-site and off-site stakeholders. Examples of plume maps and work products generated from the Triad-based investigation are available here (PDF, 3.7 MB).
609-754-0068
steffanie.metzger@mcguire.af.milTo update this profile, contact Cheryl T. Johnson at Johnson.Cheryl@epa.gov or (703) 603-9045.
