In the Spring of 2004, the U.S. Air Force (USAF) instituted the Florida Triad Initiative at three active installations representing different Major Commands. The Avon Park Air Force Range, under the direction of the Air Combat Command (ACC), selected Site Investigations (SI) at four sites to implement the Triad Approach.
Systematic project planning (SPP) for the investigations began in May 2004 and culminated with the acceptance of Work Plans for all four sites in September 2004. Fieldwork was initially scheduled to begin in September, but was postponed until December because of an unusually severe hurricane season. Once mobilized, field teams from two different contractors completed the sample collection programs at all four sites in approximately 4 weeks. Soil and groundwater contamination was completely delineated at three sites and a supplemental investigation was conducted at one of the sites to complete the investigation. Closure has been achieved at two of these sites. The remaining sites are in Remedial Action (RA) with excavation for soil followed by BioSparging for groundwater.
Highlights of the project from the Triad perspective include:
|Site Name||Avon Park Air Force Range|
|Location||Avon Park, FL|
|Site Type||Federal Facility|
|Project Lead Organization||U.S. Air Force|
|Project Lead Type||U.S. Air Force Lead|
|Regulatory Lead Program||Voluntary Cleanup Program|
|Triad Project Status||Field Program Completed|
|Reuse Objective Identified||Yes|
|Proposed Reuse:||Recreational and/or Military Training|
Avon Park Air Force Range (AFR) covers about 106,000 acres in central Florida. The vast majority of this acreage is unimproved land used for a combination military training, cattle ranching, and recreation. The four sites selected to be investigated under the Florida Triad Initiative are located in the cantonment area of the base and represent different historic uses by the USAF that may have resulted in the release of hazardous materials. The Triad sites included the following four Areas of Concern (AOCs):
Coal Pile (CD-110) - The Coal Pile area was formerly used for coal loading, unloading, and storage from 1943 to 1958. Use of the site during this period consisted of surface storage of bulk coal unloaded from a rail spur on the eastern side of the site. Aerial photos show a large coal pile that at times measured approximately 450 feet long and 100 feet wide. The amount of coal stored in the area appears to have varied resulting in changes to the dimensions of the coal pile from year to year. Since the coal was stored on the ground, it was assumed that residual coal particles remained on the site. In addition, wind and precipitation would have likely dispersed finer coal particles to areas around the coal storage area. Coal is not classified as a hazardous material; however, constituents of stored coal (PAHs) could potentially leach into soil and groundwater.
Former Petroleum AST Site (SS-112) – The former Petroleum Aboveground Storage Tank (AST) Site was apparently used for bulk petroleum storage from about 1943 to the early 1970s. Aerial photographs from this period show between two and six storage tanks present at the site along with associated concrete pads and an access road. The site is currently vacant and covered in mature vegetation. Remnants of the former ASTs, associated pads and the access road are not currently visible. Contaminants of concern (COCs) include metals, PAHs, and fuel hydrocarbons.
Former Salvage Yard (MY-114) – The Former Salvage Yard appears to have been used to store various salvage items beginning in the 1940s. Aerial photographs indicate the presence of two buildings along with apparent debris piles in 1943. By 1945, much of the debris is no longer visible. Photographs taken in 1953 indicate no visible surface debris, minimal surface soil disturbance, and the return of vegetation across the site. A site visit conducted in June 2004 revealed the presence of a remnant building foundation, widely dispersed metallic debris (small metal fragments and rusted buckets), and a single large debris pile (old aircraft parts, a rubber aircraft fuel bladder and several badly rusted 55-gallon drums). The lack of specific historical information on the types of material stored at the Salvage Yard resulted in a fairly broad analyte list including volatile organic compounds (VOCs), PAHs, pesticides, polychlorinated biphenyls (PCBs), and metals.
Old Civil Engineering (CE) Yard (SS-100) – A variety of activities have been performed within the CE Yard over the last 60 years including vehicle maintenance, range target maintenance, painting, and welding. In addition, the CE Yard was a storage site for potentially hazardous materials such as petroleum, lubricants, and pesticides. Since the 1940s, a number of structures have been constructed and removed within CE Yard. Several environmental investigations have occurred at discrete locations in the CE Yard where past practices indicated that releases might have occurred. These investigations identified low levels of fuel hydrocarbons and PAHs in soil.
Each of the AOC sites (Coal Pile, Former Salvage Yard, and Former AST Site) contained discrete areas of contamination indicative of historic releases. Despite the presence of visible coal particles, only one sample location from the Coal Pile AOC exceeded the Florida cleanup level for PAHs, with no groundwater impacts. At the Former AST Site, soil results were non-detect for PAHs, TPH and lead. However, low concentrations of xylene (33 micrograms per liter (µg/l)) and isopropyl benzene (4.0 µg/l) were measured in groundwater collected from one monitoring well. Further evaluation of groundwater at the site revealed that the contamination was limited to within site boundaries. In both AOCs, soil contamination will not require further action. The proposed remedy for the minor VOC contamination within the Former AST Site is Monitored Natural Attenuation (MNA).
Metal contamination was detected at three locations within the Former Salvage Yard. Mercury and arsenic were detected above residential and ecological screening levels. A limited soil removal was proposed to remove surface soils that exceed Florida cleanup levels. Groundwater samples from two locations in the Former Salvage Yard contained aluminum and iron concentrations above applicable cleanup levels. Elevated concentrations of these metals had been detected at other sites at Avon Park possibly representing site-wide geological conditions at the base. Continued area wide-sampling was conducted to evaluate whether or not these elevated concentrations represented contamination. Where elevated concentrations were detected above industrial Florida Soil Cleanup Target Level (SCTLs), the soil was excavated. The ecological risk assessment found that no ecological risk existed at the Site.
Contamination within the Old CE Yard varied considerably in terms of spatial distribution and type. Low PAH concentrations were detected across the site, but exceed the residential target levels at only 11 of 92 boring locations. Benzo(a)pyrene was detected most frequently at concentrations ranging between 0.11-1.6 mg/kg. Most of the exceedances were clustered in the northwestern and southern portions of the compound.
Metals contamination, particularly arsenic, was also detected in the CE Yard. Arsenic detections above the industrial cleanup level (3.7 mg/kg) tended to be scattered along the eastern side of the yard and in the drainage swale at its western boundary. The drainage swale drains into a marshy area outside the boundary of the CE Yard, which also contained elevated metals concentrations. Due to communications difficulties, the field team did not fully delineate the metals contamination beyond the predetermined boundaries of the investigation. A second supplementary mobilization was conducted to complete the delineation. The final approved remedy for the Old CE Yard was excavation of soils with contaminant of concern (COC) concentrations above the residential SCTLs, groundwater monitoring for iron, institutional controls for soil, and groundwater use restrictions.
The primary objective of the Triad Approach program was to plan and execute an iterative Site Inspection (SI) and Remedial Investigation (RI) at four sites in an accelerated manner with a minimum number of field mobilizations. The goal was to conduct complete investigations and develop closure strategies for the sites in a matter of months rather than years.
This project was part the USAF’s Florida Triad Initiative. The purpose of this initiative was to promote implementation of the Triad Approach at three USAF facilities in the state of Florida, and also to position the USAF for a broader future application of the Triad Approach in order to comply with USAF’s new performance-based management (PBM) initiatives. In the past, site characterization practices depended on a multistage investigation process intended to provide sufficient site information to construct a CSM. These practices led to delays in restoration of sites at substantial costs. The Triad Approach attempts to characterize sites in a single field staging event.
This single staging program requires more intensive up-front planning and funding than conventional practices; however, subsequent field efforts and staging are eliminated generating some cost avoidance, but more importantly, saving time.
The initial characterization was conducted as a SI after completion of Pas for each site. The goal of the site characterization effort was to continue fieldwork within the same mobilization to the level of a RI and provide adequate data to support a Feasibility Study (FS) if contamination was found to be present. In practical terms, the investigative approach combined the SI, RI and FS phases of the project into a continuous effort resulting in a significantly reduced schedule.
The entire project team believed that progress at all four sites was accelerated due to the Triad Approach. Regulators and technical team members both agreed that complete delineation of soil and groundwater contamination at the base’s four Triad project sites accelerated remediation efforts 3 years ahead of where they would be using more conventional approaches to project planning, site characterization, data reporting, and data interpretation.
Utilization of high-resolution site characterization (HRSC) concepts under the Triad Approach also resulted in increased data density. Stakeholders positively commented that they had greater confidence in making decisions about the sites as a result of the greater number and relevance of sample locations.
Based on past experience at Avon Park and other similar USAF installations, the approximate cost of conducting a SI would have been $250,000 per site. Since all four sites included in the initial Triad implementation at Avon Park would have required an RI, the cost per site would have increased by $500,000. The programmatic budget to completely delineate all four sites would have been between $3.1-3.3 million (estimated).
Contractor expenses for the work actually completed at the time this profile was written was approximately $1.42 million. When government oversight and participation is added in at an estimated rate of 10%, the total cost of the project using the Triad approach is estimated at $1.6 million. Based on above programmatic budget estimate of $3.1 to $3.3 million, the cost of implementing the Triad Approach at Avon Park is therefore estimated to have resulted in a 50% reduction in the cost of a SI and RI using more conventional investigative procedures.
In addition to a significant cost savings, the consensus of the project team is that implementation of the Triad approach at Avon Park advanced progress at the four sites by approximately 3 years. Compressing the SI and RI investigations into one mobilization eliminated a whole phase of data interpretation, document production, and review resulting in lower project costs in a shorter timeframe.
SPP efforts for the Triad-based investigation at Avon Park began in July 2004 with an initial meeting including technical, managerial, and regulatory team members. Contractor personnel prepared the initial draft of the CSM for each AOC based on the results of the planning meeting and the available data for each site. The CSM for each site provided a description of potential release mechanisms, potential contaminants, and potential exposure pathways. The team then developed sampling strategies to address specific questions regarding possible contamination at the Site, while fulfilling State of Florida sampling requirements.
Planning continued during development of the Work Plans for each AOC and focused on establishing technically defensible decision criteria to allow the field team to identify and close data gaps as they arose. The pre-mobilization sampling strategy used a combination of biased and randomly selected sample locations with specific criteria for additional sampling based on the results from the pre-selected locations. Decision uncertainty was also managed by the use of low cost microextraction analytical techniques that allowed increased sample data density and rapid turnaround at a lower cost than conventional analytical procedures.
Generally, collaboration within the team has been effective. Technical and regulatory challenges have been discussed and resolved without impacting the progress of the project. One portion of the planning effort that did not receive enough attention was the data management and communication strategy. The team has experienced some difficulty in exchanging data in a timely manner. Consequently, the ability to implement a truly dynamic work strategy (DWS) was reduced.
The project team was composed of environmental engineers, risk assessors, biologists, geologists and chemists.
All fieldwork was planned and executed in a consolidated and accelerated manner with a minimum number of field mobilizations. It was the goal of the Triad team to aggressively plan and execute the investigations and avoid the more conventional approaches to site characterization that often resulted in protracted phases of work with extended idle periods between phases.
The data collection approach at each of the four sites investigated using the Triad Approach differed slightly depending on historic uses and potential release mechanisms. In general, statistical tools were used to determine the optimum sample density for soil samples to locate a potential hotspot or release site with 50 foot spacing on a triangular grid with a 95% confidence level. Sample density was increased at locations within each area where past uses or features indicated a higher probability of being a source or release point. Soil sampling decision criteria were developed to allow the field team to respond to near-real time analytical results. When contamination was detected, additional soil sampling was conducted around the detection to provide higher-resolution detail on the horizontal and vertical extent of contamination. In addition, soil sample results were used by the field team to locate groundwater sample locations in an effort to evaluate the potential impact to groundwater.
Field and laboratory results were posted to a file transfer protocol (ftp) web site for use by the entire team during the field effort. Unfortunately, delays in posting data to the ftp site and difficulty of some team members in accessing the ftp site resulted in an incomplete picture of results during the mobilization. Consequently, only personnel in the field had an up-to-date picture of progress and results of the investigation. This breakdown in communication and data management compromised the team’s ability to fully recognize emerging data gaps and respond to changes in the CSM early in the project. The team is now using an alternate web-site to share data resulting in clearer lines of communication and an enhanced capacity to work dynamically while the field team is mobilized. The existing performance based contract (PBC) expires in fiscal year 2012 and a new data management strategy will be addressed during the new contract award.
Decision criteria were included in the Work Plan for each of the areas under investigation. The criteria were also diagramed so that the field team could easily evaluate the analytical results and make appropriate decisions on when and where to conduct additional sampling. The criteria were fairly simple: once a sample result indicated contamination above Florida’s SCTL, additional sampling would be conducted around the detection at half the distance of the next grid point to completely delineate the exceedance. In addition, contaminant levels above the SCTL triggered groundwater sampling downgradient from the soil contamination to evaluate potential groundwater impacts.
A fixed-base laboratory using standard and modified SW-846 methods conducted the majority of chemical analysis for this project. Significant cost savings were achieved by using a microextraction procedure for PAH analysis that enabled the fixed-base laboratory to provide quick turnaround data at a cost lower than a mobile on-site laboratory could have. When microextraction results indicated the presence of PAHs, the sample was then analyzed by conventional extraction methods to provide data that met State of Florida requirements. This analytical approach allowed the team to obtain a collaborative data set tailored to the project decisions.
In addition to fixed-base laboratory analysis, the field team also utilized field-based methods for analysis of groundwater and soil samples for petroleum hydrocarbon, VOCs, and PAHs. The SiteLAB® Analyzer technology distributed by Strategic Diagnostics Inc. provided a rapid evaluation of groundwater and soil samples. These data were then used to select additional sampling locations and guide decisions on which samples should be shipped to the fixed-base laboratory for analysis. An informal demonstration of methods applicability (DMA) study was conducted prior to the start of the investigation to evaluate the performance of the SiteLAB® Analyzer. In addition, performance of the SiteLAB® Analyzer was monitored during the field effort by comparing split results between field and fixed-base laboratory results.
TQRS not prepared
Data quality indicators of precision, accuracy, representativeness, comparability, and completeness (PARCC) were assessed by the following data quality control (QC) parameters: daily calibration checks; method blanks; trip and purge planks; surrogate spikes; matrix spikes and matrix spike duplicates (MS/MSDs) (groundwater samples only); and laboratory and field duplicates.
Performance of the SiteLAB® Analyzer and PAH analysis using microextraction was constantly assessed by comparing the results of these analyzes with fixed-base laboratory results across a range of concentrations. The frequency of collection and analysis of field and laboratory QC samples met the quality assurance project plan (QAPP) requirements. Quality review of data submitted by the off-site laboratories found all data to be fully usable for its intended purpose with only minor qualification.
The initial data management approach used by the team was based on data summary spreadsheets and maps uploaded to a ftp site. This proved to be inadequate and cumbersome for some team members. During the course of the field investigation, an alternate web site was established with more graphical representations of analytical results posted daily. This approach streamlined data assimilation and interpretation for the entire team and helped quicken the pace of decisions during mobilization of the field crew.
To update this profile, contact Cheryl T. Johnson at Johnson.Cheryl@epa.gov or (703) 603-9045.