Stephen J. Graham, PE
Foster Wheeler Environmental Corporation

James J. Mayberry, CHP
Foster Wheeler Environmental Corporation
presently working for Dames & Moore

Robert Berlin, DPH, PE
Berlin Associates

A Fortune 500 company has recently undertaken decontamination and decommissioning (D&D) activities to address cleanup criteria under both the Nuclear Regulatory Commission Site Decommissioning Management Program and the U.S. Environmental Protection Agency Resource Conservation and Recovery Act (RCRA). Decontamination and demolition have been performed on a 18,000 square meter complex of buildings which exhibited elevated levels of mixed or RCRA waste involving uranium, metals, solvents, asbestos, and oils. Additional D&D activities are planned to address adjacent soils and lake sediment also contaminated with mixed wastes or by RCRA wastes only. This paper describes innovative strategies and techniques being applied to achieve overlapping cleanup criteria in a practical, cost effective manner.

A Fortune 500 corporation manufactured nuclear fuel using low-enriched (and depleted) uranium between 1957 and 1962 (Figure 1). At the owner's request, the Atomic Energy Commission (AEC) evaluated the results of a delicensing cleanup program, and provided a license termination in 1962 according to then-existing criteria. The company later converted the released building areas to metal-working manufacturing which generated cadmium, PCE and other organic solvents, PCBs, and petroleum oils in the form of dusts and spills.

Upon plant closure three decades later in the early 1990s, the facility was required to meet the new Nuclear Regulatory Commission (NRC) criteria for uranium under the Site Decommissioning Management Program (SDMP), as well as U.S. Environmental Protection Agency (USEPA) standards under the Resource Conservation and Recovery Act (RCRA) for metals, oils, and solvents and the Toxic Substance Control Act (TSCA) for PCBs. Decontamination and decommissioning (D&D) methods had to address some or all of these cleanup criteria for buildings, soil, and lake sediments due to overlapping waste contamination (Figures 1, 2).

The facility engaged Dr. Robert Berlin and Associates to further characterize the buildings for radiological contamination, and to provide quality assurance (QA) on subsequent remedial activities. Affected Areas were delineated (Figure 1) and a cleanup approach was identified in a Decommissioning Plan submitted to the NRC. The facility submitted a separate RCRA Corrective Action Plan to USEPA for cleanup of the other contaminants. Foster Wheeler Environmental Corporation (Foster Wheeler) was selected to integrate and implement these plans. Foster Wheeler utilized Ion Technology, Saratoga Springs, New York, for radiological engineering assistance and laboratory analysis for the D&D activities.

This paper illustrates how the Berlin Associates/Foster Wheeler team conducted a thorough, integrated investigation that eliminated potential inefficiencies that could have resulted from the diverse contaminants and multiple regulatory drivers. The team implemented real-time analyses in the field, further streamlining the investigation. This integrated approach was carried through to remediation to achieve the most cost effective cleanup of the entire site given its future use. Remediation approaches for specific contaminants and media were decoupled when appropriate and combined when necessary.

The facility consists of approximately 10 hectares bounded by a state highway to the east, private conservation land to the north, and by a large lake on the west and south sides (Figure 1). The entire facility is surrounded by a steel fence and employs 24-hour security personnel.

During the uranium fuel manufacturing period, only Buildings 1 and 2 existed. Building 1 contained 3,300 square meters (m²) of total area and was constructed of masonry and steel walls, concrete floors, and bar joist roof frame with a wood plank deck. Building 2 contained 1,700 m² of total area and was constructed of masonry and steel walls, concrete floor with various pits, trenches, sumps, and equipment foundations, bar joist roof frame with a wood plank deck, and built-up roofing. The office and laboratory areas (approximately 750 m²) of the building had a roof deck constructed of pre-cast concrete slabs and built-up roofing.

All radiologically contaminated solid waste produced during nuclear operations had been collected and temporarily stored in the "courtyard" area west of Building 2 until off-site disposal. A subsurface leach field disposal system handled nuclear process waste water beginning in 1957 (Figure 2). The system handled treated, monitored and decontaminated wastes from natural uranium and enriched uranium processes, and from laundry, shower, and laboratory wastes. This system may have continued to be used for non-nuclear waste water disposal until the 1970s. A dry well, lined with cinder concrete blocks and approximately eight feet deep, also operated during nuclear activities (Figure 2). An AEC-approved incinerator operated on the site starting in 1960 (Figure 2).

In July 1988, a radiation scoping survey of the plant buildings was performed as part of a multiphase environmental site assessment, resulting in an initial classification of Affected and Unaffected areas. A Decommissioning Plan for the radiological contamination of the interior walls and floors was submitted by Berlin Associates to the NRC in April 1993, and received NRC approval in December 1993. The Plan established further radiological surveys to confirm Affected Areas prior to initiating decontamination. This Characterization Survey of Affected Areas was performed in March 1994 by Berlin Associates and summarized in an August 1994 report.

In 1994, a ground penetrating radar (GPR) investigation was conducted to locate the leach field system and assess soil contamination (Figures 1, 2). Subsequently, a Site Radiological Characterization Survey program was conducted during 1994-1995 in accordance with NUREG/CR-5849 (NRC, 1993). Surface and subsurface soil, groundwater, sediment, surface water, and ambient air were analyzed for concentrations of total uranium over a 10m by 10m grid. Over 600 soil and sediment samples were analyzed, with the following results (Figures 1, 2): (1) About 10% of the soil samples exceeded a 27.5 picocurie/gram (pCi/g) "administrative clean up level" established for D&D activities. The 27.5 pCi/g represent a safety factor for not exceeding the 30 pCi/g level established by the NRC. The majority of these samples ranged between 27.5 pCi/g and 50 pCi/g; (2) Uranium concentrations exceed the NRC residual soil contamination limits (30 pCi/g) at several locations: at the leach field at 8 to 12 feet below ground surface (bgs); at the dry well at 4-12 feet bgs; in surficial locations southwest of Building 2; beneath parts of Buildings 3 and 12; and in small sediment "deltas" in the lake; (3) Uranium locations correlate well with available historical data; for example, contamination at the septic system and dry well is from liquid waste discharges, and surface contamination southwest of Building 2 and in the lake is traceable to the location of incinerator and stored waste area; and (4) Extensive groundwater investigations showed no migration of uranium from soil sources; also, radiological concentrations are at background levels for surface water and fish in the lake, and in ambient air.

A key instrument used to screen soil samples was high resolution gamma spectroscopy with high purity intrinsic germanium detectors. The principal advantages for radiological situations involving normal uranium, depleted uranium, enriched uranium, and refined uranium are: (1) the cost per analysis is low compared to alternative methods; and (2) information can be derived for all the principal nuclides of uranium, including U-238 from short lived, immediate progeny (Th-U234); U-235 from the U-235 isotope gamma; and U-234 indirectly from the U-235 and the U235/U238 ratio. Where needed, quantitation of other observed gamma emitting nuclides (e.g., K40, Cs127, Th232) can be performed on the same sample.

Detection sensitivities of less than 1 pCi/g, at the 95% confidence level, were readily achieved, and large sample volumes were directly analyzed, in contrast to methods that involve chemical processing (i.e., 800 grams vs. 10 grams). This provides analytical information that is less dependent on homogenizing the sample and, therefore, is more closely representative of the field. Short (hours) turnaround times could be achieved by field gamma ray spectroscopy compared to fixed laboratory methods that would have required extensive sample preparation and subsequent analysis over several weeks. As a QA check, 10% of field samples were duplicated and analyzed by a fixed laboratory and very close correlation was achieved. This field spectroscopy was very helpful because it enabled decision making in the field to focus the radiological soil investigations.

Also in 1994, as part of a coordinated field program, a multi-phase site assessment was initiated under an EPA Consent Order. In soil and lake sediment, "mixed waste" containing uranium, cadmium, or PCBs, was found to coexist (Figure 2). In Building 2, metals, solvents, oils, and asbestos were also present, although not mixed. In Building 1 and eight other buildings totaling 18,000 m², metals, solvent, and oil contamination was found to occur.

The end result of these combined investigations was to determine that there were approximately 18,000 m² of RCRA contaminated building, including 1,700 m² of building also exhibiting radiological contamination, and 2,600 m³ of radiologically contaminated soil and sediments in the exterior regions of the site, consisting of 2,200 m³ of radioactive (only) materials, and 400 m³ of mixed waste. These quantities include small areas, or pockets, of soil underlying the Building 2 concrete floor slab. Approximately 2,200 m³ of soil and lake sediment contaminated by RCRA waste only also were determined to be present.

Upon our recommendation and after negotiation with the affected regulators, the facility decided to implement an integrated program involving three separate, yet coordinated remediation projects. These projects respond to the different regulatory criteria and schedules, and also to reflect the clients' annual budget allocations. These projects consist of: (1) uranium and RCRA contaminated building D&D; (2) uranium contaminated soils and lake sediment D&D; and (3) RCRA/TSCA waste contaminated soil remediation.

The facility owner plans to bring a new manufacturing mission to the facility. To meet this plan, most of the buildings were to be demolished. Exterior soils and lake sediment would be remediated using risk based criteria given continuing control and security of the facility. The most cost effective approach to this remediation was to identify areas that could be decoupled from other areas on the site and readily remediated to the cleanup criteria, minimizing areas that require long term management.

The overall scope of this project was to eliminate radiological and RCRA contamination. Radiological, RCRA, and TSCA contaminants existed in the buildings. However, Building 2 was the only building with radiological contamination and this contamination was not commingled with either the RCRA contaminants or PCBs. Therefore, the buildings could be decontaminated without generating mixed waste.

Remediation Objectives for the Affected Areas met the NRC cleanup criteria for uranium as follows:

Radiological decontamination was conducted under an NRC approved Decommissioning Plan and Radiological Health and Safety Plan. First, residual equipment was removed from Building 2. Then, floor and wall surfaces were decontaminated using abrasive techniques, primarily scabbling. Decontamination operations were supported by continuous surface scans with a large area gas proportional detector. These Remedial Control Surveys served to direct the progress of the operations. Once decontaminated, floor slabs were cut to remove under-slab piping and any associated contaminated soil. Additionally, contaminated floor joints were cut out and packaged as radioactive waste and associated contaminated soil removed. Any contaminated soil found around drain piping less than or equal to 4 feet below grade was removed as part of this interior program; uranium contamination found beneath 4 feet was addressed in the soils/sediment program. A final status survey for the building surfaces and exposed soils was conducted and documented according to NUREG/CR-5489.

RCRA decontamination was conducted once elevated uranium was removed. Generally, radiological and RCRA materials coexisted but were not intermingled in Building 2, such that contamination could be removed in series without generating mixed waste. The exception was some uranium contaminated asbestos that was discovered, remediated, and handled as uranium contaminated waste.

The other buildings were decontaminated and demolished down to the floor slab. Following a confirmatory survey by the NRC, all formerly contaminated buildings (18,000 m²) were demolished.

For the exterior soils and lake sediments, it is most cost effective to integrate the remediation of RCRA and radiological constituents. The cleanup criteria for RCRA constituents are risk based and factor in the continuing control of the property by the owner. This control, coupled with deed restrictions, enable large volumes of contaminated soil to remain on-site.

Radiological cleanup criteria is based on SECY-81-576. This document establishes five possible remediation options. These options are risk based and were developed based on generic site conditions. Of the five options, Option 3 deals with natural uranium ore and is not applicable to this Site. Option 5 includes continued maintenance of an NRC license. Since the facility does not currently possess a license, this option was disregarded. Table I presents the maximum concentrations associated with the three remaining options. These options can be characterized as follows:

• Option 1 is a No-Action option, i.e., the soil can remain in place and the site released for unrestricted use without remediation. This option is not viable for this site, since uranium concentrations exceed the 30 pCi/g limit.
• Option 2 allows for unrestricted release of the site after adding a 4-foot earthen cover over the contaminated soil. Most areas on the site fall within this option.
• Option 4 allows for restricted release of the site. Like Option 2, it requires a 4-foot earthen cover. However, additional controls, such as deed restrictions, are also required.

Presently, a D&D Plan based on using a combination of Options 2 and 4 has been submitted to the regulators, and is awaiting approval.

Specific rationale for selecting these options is as follows: (1) The decommissioning is consistent with the remediation of soil containing EPA-regulated materials, which also includes providing deed restrictions identifying the hazards constituent present on site and limiting future use, assuming an industrial use at the site, and industrial soil cleanup levels; (2) The maximum soil concentration for total uranium is, with limited exceptions which will be removed, well below the 2,500 pCi/g limit provided in SECY 81-576 (NRC, 1981). Additionally, only a few areas have contamination greater than 100 pCi/g, making implementing these options very protective of human health and the environment; (3) On-site disposal eliminates the need for excavating large volumes of material and transporting the material to a disposal facility. These actions would likely lead to risks greater than those posed by keeping the material in place, such as would be created by potential emission of dusts from excavation and during transport. The small area of the lake with shallow sediment deposits and other small areas at the margin of the lake, as needed, will be consolidated into an existing topographic low area in the courtyard area, and then covered with a 4-foot minimum thickness of clean cover; (4) The topographical, geological, hydrogeological, and meteorological characteristics of the site combine to minimize any long term dispersion potential. These site features, coupled with a four foot deep cap, prevent material from migrating off-site; and (5) The facility plans on long term ownership of the site, including bringing in a new manufacturing mission to the other Unaffected Areas of the site, while maintaining security over the entire facility, and managing a long term groundwater monitoring and maintenance program.

A radiological dose and risk assessment has been performed for the site based on the intention to consolidate that part of the surface and near surface soils and sediments in the south courtyard which exhibit elevated radioactivity . This material would be consolidated, if needed, and capped with a minimum four foot thick cover to provide shielding from potential gamma emissions to eliminate the potential for release of dust.

The exterior program activities at the site are listed in Table II. The radiological risk assessment performed, per U.S. Department of Energy (DOE) guidelines, estimated that after completion of decommissioning/remediation activities, an on-site worker would receive a total effective dose equivalent of less than 0.1 millirem (mrem). There are no viable pathways for off-site exposure after decommissioning/remediation activities have been completed, with a corresponding Excess Cancer Incidence Risk of 1.9E-6. This maximum occurs far in the future (greater than 1000 years) due to the ingrowth of radon over time.

Only one risk scenario for radioactivity dosage exposure is applicable to the site. This scenario is the realistic assumption of workers continuing to be present on the site or the remainder of the facility. Projected impacts have been calculated (DOE, 1993).

Site characteristics, material properties, and nuclide concentrations are assumed to be the same as used in the baseline assessment reported in the Site Characterization Report. The modification for the future scenario is accomplished by adding the cover above the consolidated material.

A complex site involving mixed waste contamination of multiple media -- buildings and associated structures, soil, and lake sediment -- is being remediated through innovative strategies and techniques. A comprehensive remediation program has been undertaken which integrated investigation activities occurring on multiple media and types of wastes under three separate federal regulatory programs. The potential end uses of the property were the basis for selection of remedial methods and extent of cleanup required. This provided greater field efficiency and lower cost to the client, and better matched the regulatory oversight imposed by the government. This also allowed discrete portions of work to proceed to conclusion, instead of waiting for individual government agencies to approve the technical approach for all project work.

Utilization of available but little-used NRC contamination management alternatives, and of relatively new tools, such as risk assessment and risk-based remediation, has allowed contaminated soils to be consolidated and remain on-site instead of being excavated and removed off-site at considerably higher cost. The use of innovative techniques, such as an on-site laboratory providing real-time data, yielded significant cost savings and allowed field investigations to proceed rapidly and conclusively to eliminate the need for further assessment. Radiological surveys conducted throughout the project also allowed real-time measurements to verify the effectiveness of remediation, and provided a final cleanup program readily accepted by NRC field inspectors.

1. NRC, 1993. NUREG/CR-5849. "Manual for Conducting Radiological Surveys in Support of License Termination", December 1993.
2. NRC, 1987. "Guidelines for Decontamination of Facilities and Equipment Prior to Release for Unrestricted Use or Termination of Licenses for Byproduct, Source, or Special Nuclear Material", USNRC, August 1987, Table 1, Acceptable Surface Contamination Levels.
3. NRC, 1981. "Disposal or On-site Storage of Residual Thorium or Uranium (Either as Natural Ore or Without Daughters Present) From Past Operation", a Branch Technical Position (BTP) issued by NRC's Uranium Fuel Licensing Branch, SECY 81-576, October 5, 1981.
4. DOE, 1993. "Manual for Implementing Residual Radioactivity Material Guidelines Using ResRad Version 5.0", a risk assessment program developed by the U.S. Department of Energy, September 1993.

Special appreciation is expressed to Kevin Wood, Foster Wheeler Project Sponsor, and Steve Miller, Ion Technology, for their support and technical advice on this project.

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