Michael Redmon and Melissa Kucera
Bechtel National, Inc.

This report focuses on remedial action during 1997 conducted by the Formerly Utilized Sites Remedial Action Program (FUSRAP) at the Ventron site in Massachusetts and the New Brunswick site in New Jersey. FUSRAP completed remedial action at these two sites, including building decontamination and excavation of contaminated soil and sediments at Ventron. This progress report highlights cost savings achieved through innovative characterization approaches and improved remediation and material-handling methods at properties largely surrounded by water. Topics discussed include (1) remediation and material-handling methods used at Ventron, which is surrounded by water on three sides; (2) lessons learned at Ventron regarding improved protocols for interaction with the independent verification contractor; (3) lessons learned at Ventron regarding low-level uranium waste shipment using intermodal containers; (4) significant cost savings achieved through soil sorting using the segmented gate system for volume reduction during remediation of the New Brunswick site; and (5) planned start of characterization at the Combustion Engineering site in Connecticut.

The mission of the Formerly Utilized Sites Remedial Action Program (FUSRAP) is to clean up sites with low levels of radioactive contamination and release them for use without radiological restrictions. The program was previously administered by the U.S. Department of Energy but was recently transferred to the U.S. Army Corps of Engineers (USACE). Most FUSRAP sites were contaminated with low-level radioactive waste (LLW) and 11e(2) by-product material from the extraction of uranium or thorium from ores. Innovative remediation techniques are being applied to reduce costs and minimize waste production.

In accordance with U.S. Environmental Protection Agency guidance, FUSRAP has taken an integrated approach to waste minimization by first focusing on preventing the generation of waste and then minimizing waste volumes through recycling, reuse, and applying innovative technologies.

Key elements of the remediation strategies include the following:

• participation of a multidisciplinary management team to conduct a comprehensive analysis of site-specific circumstances and identify opportunities for innovative remediation strategies, cost reduction, and waste minimization;
• proactive communication with site owners, regulators, and other stakeholders to develop effective partnerships, identify site-specific opportunities and constraints, and hold early and continuing discussions regarding potential remediation strategies;
• development of risk-based cleanup criteria based on site-specific conditions and realistic future use scenarios to achieve protective yet cost-effective remedies. Evaluating plausible future use conditions together with the site owner and regulators facilitates endorsement of site-specific, risk-based criteria by the appropriate regulatory organizations; and
• innovative application of new and existing technologies to streamline the remediation process, reduce costs, and minimize waste generation.

At each site discussed, remediation was achieved through non-time-critical removal actions conducted under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) process. State and local regulators have been highly cooperative and receptive to innovative remediation strategies. For sites not yet completed, the conceptual approach to remediation is discussed, including lessons learned from the completed sites. This paper focuses on sites in the USACE Baltimore, New England, and Philadelphia districts.

The Ventron Site is located in Beverly, Massachusetts, on the Massachusetts Bay. The western and southern portions of the site are encompassed by a stacked granite seawall approximately 192 meters long and 3.6 meters high. At low tide, the seawall and adjacent tidal flats are exposed. Tidal cycles fluctuate an average of 2.7 meters.

From 1942 until 1947, Manhattan Engineer District/Atomic Energy Commission (MED/AEC) contract activities involved converting uranium oxide to uranium metal powder. Other operations involved recovering uranium from scrap material and turnings. Buildings A and A-1, which housed numerous retort furnaces, leaching facilities, and mixing equipment, were the original buildings used for these activities. Later, the site was a fully operational chemical manufacturing facility. Independent work with radionuclides, primarily thorium, was performed in the Alfa Building. In November 1994, process operations ceased, and the facility was shut down.

During remedial action planning, several factors affected the cleanup strategy. The tidal estuary setting constrained conduct of operations; space for site operations was limited; MED residual contamination was near the seawall, beneath buildings, and in the tidal flats; and a state-directed cleanup of some non-MED contaminants was being conducted by the site owners.

The tidal estuary setting required a floodplain/wetlands assessment. Floodplains, wetlands, and coastal tidal areas were present, but proposed activities were determined to have minimal short-term and positive long-term environmental effects. Because of the sensitivity of the tidal flats, the remedial action used a clam shell excavator from the land side of the site to avoid unnecessary damage to the area from heavy equipment operation.

The site owner indicated that after cleanup, buildings would be demolished and the site would be restored. The owner would then sell the property, probably for residential development. Given these plans, application of surface criteria for release of the building structures without radiological restrictions was not appropriate. Therefore, the final remediation strategy included a dose-based decontamination/demolition approach for Buildings A and A-1. Additional characterization data were collected to support calculation of the potential dose estimate for building demolition and recycling of structural steel and pipes. The calculation demonstrated that no remedial action was needed (except for decontamination or removal of some nonstructural equipment and disposal of radioactively contaminated asbestos-containing waste), so the building was relinquished to the owner for demolition. The demolition did not include the floor slabs because of contaminated soils beneath some slabs. The resulting debris met the site-specific volumetric criteria before release from the site, so the site owner could dispose of most of it in an industrial landfill.

Remediation of the rest of the site was not subject to the same space limitations as before demolition. Also, remediation of areas adjacent to the seawall could be approached in a more practical, safe, and cost-effective manner. The seawall has a vertical face, is constructed of piled rocks/boulders, and contains very little batter. Therefore, it was necessary to conduct nearby excavations methodically to prevent structural failure. The design approach limited the seawall surface area that could be exposed by an excavation and required the placement of buttress backfill before excavation. If a failure did occur, the seawall area subject to failure would be minimized, and plans were in place for responses to any localized failure. To minimize the water requiring management and to prevent contaminant transport, excavations were coordinated with low tides.

The tidal influence also presented waste management issues such as soil moisture treatment considerations before offsite shipment for disposal. A design basis was established based on pre-remedial action soil test results, which dictated acceptable moisture content of the various site soils expected during cleanup. As soils were excavated, they were stockpiled on one of the floor slabs. Any soils requiring conditioning were placed in a bermed drying/staging area and mixed with drier soils or absorbents, and additional control was accomplished by adding absorbents during loading. More than 7,600 cubic meters of low-level uranium waste was shipped offsite.

The remedial action plan also met the Massachusetts Radiation Control Program requirement that the total post-remediation dose equivalent from a site shall not exceed 10 mrem. Compliance was demonstrated through computer dose modeling of post-remedial action data. State regulatory officials were kept informed of the site activities and progress, and monthly status briefings were conducted for local citizens and public officials. State regulators also periodically visited the site to get updates and view the cleanup.

Support from the site owner and the state was essential to successful implementation of the remedial action. Cost avoidances for the approach implemented at Ventron instead of a more traditional approach exceeded $2 million.

The New Brunswick Site (NBS) in New Jersey was used for 29 years as a nuclear chemistry laboratory to support AEC reactor and weapons programs. In 1960, soils originally consisting of Belgian-Congo pitchblende were excavated from the Middlesex Municipal Landfill and mixed with site soils before placement as backfill in an abandoned rail spur area. In 1977, the facility was closed, and laboratory operations and personnel were relocated. Responsibility for remedial action was assigned to FUSRAP in 1990.

The original FUSRAP project baseline called for remedial action consisting of complete excavation of all above-criteria soils with transport for offsite disposal. However, to avoid the overexcavation typical of this approach, the Segmented Gate System (SGS), a Thermo Nuclean soil sorting system, was investigated as a potential alternative. The SGS consists of a soil conveyance system, two detector arrays, a segmented gate system, and a comprehensive software program. Before being processed through the SGS, soil is loaded into a screen plant for size reduction. As soil is conveyed beneath the detectors, decision logic routines determine whether it is routed for above-criteria or below-criteria disposition. The logic routines consist of hot particle analyses and a distributed activity analysis. Preliminary testing was conducted to ensure that segregation via the SGS would be practicable.

The NBS soils were contaminated primarily with natural uranium and radium-226. The segregation process was required to meet criteria of 100 pCi/g for total uranium and 5 pCi/g for radium-226 and for thorium-232. With such low cleanup criteria, radium-226 was the contaminant that ultimately drove the excavation process and the segregation process.

SGS operation began in mid-June 1996 and lasted 6 weeks. Of the total 6,024 cubic meters excavated, 3,640 cubic meters of soil was processed through the system; the remaining 2,384 cubic meters consisted of oversize material, asbestos-containing soil, soil removed from the processing area after the system was demobilized, and site cleanup waste. This waste was shipped directly to the disposal facility as low-level waste. A total of 2,042 cubic meters was sorted as clean material with an average uranium-238 activity approximately equal to background and an average of 1.17 pCi/g of radium-226. This soil was used as backfill in the areas of excavation. A 56-percent volume reduction was achieved for the material processed.

During processing, most of the problems encountered were from equipment failures in soil handling. Before the operations at NBS, most soils processed by the SGS consisted primarily of sand and corals. The heavy clay content of the NBS soils created problems in the screen plant and the pneumatic gate system operations. Non-soil constituents such as roots and debris that were small enough to pass through the screen plant would render the gates inoperable. Grass roots created so many problems that the decision was made to remove the topsoil before resuming processing. Valuable experience with the high clay content soils at NBS has resulted in modifications by Thermo NuTech to improve the material handling capabilities of the system.

Another important soil characteristic that can influence system efficiency is the distribution of the radioactivity. In areas with high concentrations of radioactivity, some excavation and loading techniques mixed the soil so the entire volume was diverted as contaminated. To avoid this, operations were altered to load soil more directly and decrease mixing. In soils with low levels of radioactivity, no differences were noted in efficiencies and loading techniques.

Based on the total waste volume of 6,024 cubic meters and transportation to the disposal site via rail gondolas, the remediation estimate for complete excavation with no processing was $5.5 million. After volume reduction, the cost of transportation and disposal of the final site volume was $4.2 million, a cost avoidance of $1.3 million.

FUSRAP authority for remedial action at this site in Connecticut is limited to areas that were affected by AEC activities: Buildings 3/3A, 5, and 6; the associated drainpipes and sewer lines; a waste pad storage area; a drum burial site; and a brook. Cleanup will be restricted to uranium contamination enriched to 20 percent and greater. The primary complexity of this cleanup is the need to distinguish between FUSRAP waste and waste for which the site owner will be responsible. The conceptual approach to site characterization will require delineation of the areas with uranium enrichment of greater than 20 percent, followed by determination of the nature and extent of contamination exceeding final cleanup criteria. Identifying applicable technologies for field screening for percent enrichment, such as in-situ gamma spectroscopy, will be critical to ensuring a cost-effective and thorough site characterization. For historical burial areas, technologies such as electromagnetic surveys and ground-penetrating radar will be used to focus sampling and analysis on contaminant boundary delineation. For the onsite drainpipes and sewer lines, technologies such as the pipe explorer will be used because of their success at other FUSRAP sites. For remedial action alternative development, several regulatory authorities will be involved because of the other radioactive waste that will not be remediated by FUSRAP. If areas of co-located waste are found, cost sharing options with the site owner will be considered.

A more traditional approach to characterization will be probably be used at this site. The known areas of FUSRAP responsibility are limited to an onsite building and a waste burial area (and the immediate vicinity) included in a larger onsite landfill. Approximately 27,360 cubic meters of FUSRAP waste is present, and sampling and analysis will be conducted to better define the nature and extent of contamination. Remedial alternatives will probably include a detailed evaluation of an onsite remedy because most of the waste is part of a larger landfill. If the contaminant levels are typical of other FUSRAP sites, a risk/dose assessment will probably show that a permanent cap over the landfill, including the radioactive waste burial area, will be a cost-effective and protective remedy. However, if major excavation is required, lessons learned from the tidal influences at the Ventron site will be beneficial because this site is also on a bay.

Several areas of this facility have been identified as containing radioactive waste for which FUSRAP has responsibility. These areas include an onsite building, a central drainage ditch (for plant waste discharge), a burial area underneath a parking lot, and an area near an onsite waste lagoon. Two important interim actions have been completed at the site. First, a dose/risk assessment of the building concluded with a gross decontamination effort, to be followed by demolition and sanitary landfill debris disposal; under a cost-sharing agreement with the property owner, demolition and non-metal debris disposal will be completed by DuPont, while FUSRAP will dispose of the metal debris. Second, the site owner was required by a Resource Conservation and Recovery Act (RCRA) corrective measure to remediate the central drainage ditch because of lead contamination. The lead was not a FUSRAP waste, but uranium was mixed with the lead in some areas. After demonstrating that disposing of the uranium in the onsite RCRA cell was a protective alternative, FUSRAP and DuPont worked with regulatory agencies to obtain approval for including uranium with the lead waste stream that was to be placed in the onsite cell. FUSRAP waste from other site areas will also be considered for onsite disposal in the RCRA cell because of the cost-effective and protective nature of this remedy.

Although this National Priorities List site has been included in FUSRAP, the federal government has not been named as a potentially responsible party (PRP). Therefore, maintaining the site in the program is being evaluated. Typically, if other PRPs are identified, sites are not included in FUSRAP. FUSRAP involvement began during the early 1980s when an emergency response action was completed to remove highly enriched uranium. A site characterization was then completed to determine the full nature and extent of radioactive contamination. Since then, FUSRAP has maintained a level of involvement at the site. However, the PRPs are now conducting a remedial investigation/feasibility study without FUSRAP involvement. The selected remedial action by the PRPs is expected to sufficiently address the radioactive contaminants. Otherwise, a FUSRAP remedy will probably consist of an onsite scenario because this site adjoins a major sanitary landfill that is undergoing final closure.