This report contains information about on-site soil contamination and soil cleanup options at Brookhaven National Laboratory (BNL). BNL is conducting an environmental cleanup under the requirements of the federal Comprehensive Environmental Response, Compensation and Liability Act of 1980.
The BNL site has been subdivided into six Operable Units (OUs) for the purposes of the environmental cleanup (OU I, OU II/VII, OU III, OU IV, OU V, and OU VI). An "Operable Unit" is an administrative name for a specific geographic area or a site-wide environmental system, such as contaminated soils or groundwater. Within these six Operable Units, areas of suspected contamination were divided into Areas of Concern (AOCs) for the cleanup process. These Areas of Concern have been investigated to determine the nature and extent of contamination.
Purpose of this Report
This Feasibility Study report addresses contaminated soil and sediments from OU I and OU VI, and radiologically-contaminated soils from OU II/VII and OU IV. The majority of contaminated soils evaluated for remediation in this feasibility study are in OU I, with the other Operable Units contributing significantly lesser volume. The purpose of this feasibility study is to identify, develop, screen, and evaluate a range of cleanup alternatives for this contamination. The main objective of this report is to provide BNL stakeholders with enough information to choose a feasible and cost-effective remedial alternative that protects public health and the environment.
BNL contains contamination other than the radiologically-contaminated soils/sediments from OU I, OU IV, and OU VI. This other contamination is being or has been addressed in other feasibility studies or engineering evaluation/cost analysis reports and is not within the scope of this feasibility study.
Brookhaven National Laboratory is located on Long Island, New York. BNL is a Department of Energy (DOE) facility, currently operated by Brookhaven Science Associates. In December 1989, BNL was placed on the U.S. Environmental Protection Agency National Priorities List.
OU I occupies 960 acres in the southeastern part of BNL and is largely undeveloped. Small sections of OU I were historically used as waste handling areas for BNL. Waste was disposed at several closed landfills and disposal areas in OU I. In addition, surface and subsurface soil contamination from spills and waste processing has occurred in BNL's Former Hazardous Waste Management Facility (HWMF), which was a permitted facility with limited access. The Former HWMF was closed in 1997. Areas of Concern in OU I addressed in this report include AOC 1, the Former HWMF; AOC 2F, the Ash Pit; AOCs 24E and 24F, two recharge basins; and a wooded wetland near the closed Current Landfill.
OU VI is located on the eastern edge of BNL, directly north of OU I. It is a largely wooded area which contains various experimental biology and agricultural fields. The Meadow Marsh Area sediments, part of AOC 8, are considered in this report.
OU II/VII is located in the central, developed portion of BNL. Four Areas of Concern and their associated sub-areas have been evaluated in this feasibility study. The areas evaluated include AOC 10A, the soils at the Waste Concentration Facility, AOC 10B, the Underground Pipeline at the Waste Concentration Facility, AOC 10C, the underground storage tanks, AOC 16, various isolated areas of low-level radioactive surface soils identified by the Aerial Radioactive Monitoring System Results, AOC 16K, the Brookhaven Linac Isotope Producer, AOC 17, the Area Adjacent to the Former Low-Mass Criticality Facility, and AOC 18, the Alternating Gradient Synchrotron Storage Yards.
OU IV, located on the east-central edge of the developed portion of BNL, contains AOC 6, the Reclamation Facility Building 650 Sump and Sump Outfall area, where radiological soil contamination has been identified.
Extent of Soil Contamination
Remedial Investigations and Risk Assessments were conducted for each of the Operable Units evaluated in this feasibility study. The Remedial Investigations evaluated the nature and extent of contamination in soils and/or sediments. The Risk Assessments determined the risk to receptors in both the present and future from the identified contamination. The most significant areas of contamination are discussed below.
In OU I, radiological soil contamination at the Former HWMF is above risk-based remediation goals for any future use. Because of the volume of contaminated soil, this area is the principal focus of this feasibility study. The predominant radionuclide identified is cesium-137 (Cs-137), which, through decay, results in a gamma-ray emission. This emission is a major source of direct exposure risks from soils. Levels of strontium-90 (Sr-90), a beta emitter, are also of concern, because they pose a potential future ingestion risk if strontium-90 migrates to the groundwater. Both of these radionuclides are relatively short-lived with half lives of approximately 30 and 28 years, respectively. Small, isolated areas of very low levels of alpha contamination from plutonium and americium in surface soils were also identified in the Former HWMF.
At AOC 2F, the Ash Pit, elevated levels of lead in ash exposed at the surface represent a potential human health risk. Several remedial alternatives for the Ash Pit are evaluated in Appendix O of this report.
Areas exhibiting potential ecological risk, but no human health risk, are also addressed in this feasibility study. A potential for ecological exposure to potentially significant levels of contaminants was identified for several areas in OU I and OU VI that are breeding grounds for a New York State endangered species, the tiger salamander. An additional ecological risk assessment was conducted for these areas and is included in Appendix L of this report. Based on elevated levels of potential risk to the tiger salamander, remedial alternatives for OU VI/AOC 8, the Meadow Marsh ponds, are evaluated in Appendix O of this report.
In OU II/VII, radiologically-contaminated soils were identified in AOC 10A, at the Waste Concentration Facility. Surface soils are contaminated with Cs-137 and Sr-90. Two subsurface sample locations also contained elevated levels of both these radionuclides. AOC 16 includes isolated radioactive landscaping soils which were identified in an aerial survey. Surface soils contain Cs-137 and other radionuclides that exceed risk-based remediation goals for future residential use. AOC 16K, the Brookhaven Linac Isotope Producer, contains subsurface soils contaminated with sodium-22, tritium and other short-lived radionuclides.
In OU IV, AOC 6 includes several areas adjacent to Building 650 where radiological soil contamination has been identified. Contaminated areas include limited soils to the north of the building where run-off from an outdoor decontamination pad flowed. Also included are soils along an 800-foot pipeline, and at the pipeline terminus, known as the Sump Outfall area. A number of longer-lived radionuclides were identified in AOC 6, including plutonium, uranium, and americium. In addition, cesium-137, europium, cobalt-60, radium-226, and strontium-90 were identified in the Sump Outfall area. Because the mix of radionuclides in OU IV is different from other radiologically-contaminated soils at BNL, soil contaminated with long-lived (up to 24,390 years) isotopes will be kept segregated from soils with short half-life radionuclides.
Radiological sampling of deer meat has been conducted by BNL and the New York State Department of Environmental Conservation (NYSDEC) from 1992 to 1998 to evaluate the potential risk to hunters who consume deer meat (NYSDEC, 1999; BNL 1998; BNL 1999). On-site deer and deer from the vicinity of BNL were determined to have maximum Cs-137 levels of 11.74 picoCuries per gram (pCi/g) and 6.56 pCi/g, respectively. This is greater than the maximum level measured in off-site deer of 0.90 pCi/g. The projected average and maximum dose associated with consumption of contaminated deer meat was estimated to be 5 millirems per year (mrem/yr) and 9 mrem/yr, respectively. Both dose estimates are below the NYSDEC dose limit of 10 mrem/yr, which is a cleanup goal rather than a food consumption goal. The lifetime cancer risk from one year of consumption for average conditions was estimated to be four in one million (incidence rate) and two in one million (mortality rate). Both risk estimates are within the Environmental Protection Agency acceptable risk range of one in 10,000 to one in a million. As a result, NYSDEC has recommended that hunters be advised of elevated Cs-137 concentrations in deer close to the BNL site. However, no additional formal restrictions need to be placed on hunting in areas adjacent to BNL. Hunting on BNL continues to be prohibited.
Chemical risks for potential future land uses were identified in OU I within the Former HWMF due to mercury, in areas that coexist with radiological contaminants. Chemical contaminants coexist with radiological contaminants in certain areas. The levels of chemical contaminants do not exceed risk-based remediation goals, but may render these soils mixed waste. Special testing and handling may be required for these soils. Note that any chemically-contaminated soils in other Operable Units are being addressed in other feasibility study reports and are not within the scope of this feasibility study.
Risk-Based Soil Remediation Goals
Risk-based soil remediation goals were developed for radiologically-contaminated soils in OU I and the other Operable Units using Residual Radioactive Material Guidelines (RESRAD), a DOE-approved computer model. The remediation goals for most radionuclides were calculated to achieve an allowable exposure dose of 15 mrem/year. The New York State Technical and Administrative Guidance Memorandum 4003 guideline of an allowable exposure dose of 10 mrem/year is considered a further goal to be achieved, if possible, through As Low As Reasonably Achievable (ALARA) measures.
Since BNL is currently owned by the Federal government and will continue to be under Federal ownership for the foreseeable future, remediation goals were developed for potential future uses in the event that the property is released for other uses. The future use assumption for the OU I Former HWMF is industrial/commercial, after 50 years of Federal ownership and Federal institutional control for Alternative 4 and after 100 years of Federal ownership and Federal institutional control for all other alternatives. The future use assumption for the other Operable Units is residential, after 50 years of Federal ownership and Federal institutional control. The more conservative residential future use for the other Operable Units, which are located in the central developed part of the BNL facility, was selected as an ALARA consideration since the volumes of contaminated soil are smaller than at the Former HWMF, and will allow more flexibility for decision makers if and when BNL is eventually released for other uses in the future.
The remediation goal for the Former HWMF in OU I was developed based on a future industrial/ commercial use scenario and 15 mrem/yr dose following 50 years of Federal institutional controls. This equates to 67 pCi/g Cs-137. Note that this is approximately the same Cs-137 level (71 pCi/g) calculated in the OU I/VI Remedial Investigation/Risk Assessment Report based on a future residential use scenario and 15 mrem/yr dose following 100 years of Federal institutional control.
Because institutional controls cannot necessarily be guaranteed after the Federal ownership and Federal institutional control period, an Inadvertent Future Intrusion scenario was also developed to determine a secondary action level for certain remedial alternatives (Appendix C). Under this scenario, it was assumed that following the Federal ownership and Federal institutional control period, additional institutional controls to prevent residential use, such as deed restrictions, are not maintained and houses are built in the Former HWMF area. Residual concentrations of Cs-137 were calculated that would be in compliance with an allowable dose of 75 mrem/year, taking into account the mixing that occurs during soil remediation. The Cs-137 secondary action level calculated under the Inadvertent Future Intrusion scenario is 600 pCi/g, which represents the maximum Cs-137 concentrations that could remain under a cap within the Former HWMF and still meet the criterion of 75 mrem/year and residential use. The 75 mrem/year criterion was selected because it is a fraction of the 100 mrem/year criterion (10 CFR 834 and DOE Order 5400.5) and was also in a draft Environmental Protection Agency rulemaking for loss of institutional control.
For the other Operable Units, the remediation goal was based on an allowable dose of 15 mrem/year and residential future use, after 50 years of Federal ownership and Federal institutional control. This equates to 23 pCi/g Cs-137 and 15 pCi/g Sr-90. Table ES-1 presents a summary of the categories of radiologically-contaminated materials encountered in each of the Operable Units under consideration in this feasibility study. The categories of contaminated soils presented in Table ES-1 are based on the soil remediation goals of 23 pCi/g Cs-137 for areas in the center of the BNL site, 67 pCi/g Cs-137 for the Former HWMF, and other waste characterization, treatment, and disposal criteria that are important in this analysis. Figure ES-1 demonstrates the effect of the Former HWMF remediation goal on the volume of soil that requires remediation. Since Cs-137 was the dominant radioisotope, its concentration was used to determine the volume of soil required to be remediated.
The remediation goal for Sr-90 was determined based on its potential for groundwater contamination, using the RESRAD model. This equates to 15 pCi/g for both industrial/commercial and residential future use scenarios.
The remediation goal for radium-226 is 5 pCi/g, per DOE Order 5400.5 entitled Radiation Protection of the Public and Environment.
Remedial Action Objectives
The following remedial action objectives were established to protect human health and the environment by reducing exposure to radiologically-contaminated soils:
Preliminary Area and Volume Estimates
The estimated area and volume of soil and debris contaminated above remediation goals for OU I, OU II/VII, and OU IV is provided below. The estimated surface area (5.83 acres) comprises only a small percentage of the 5,300 acre BNL site.
Remedial Technology Evaluations
A wide range of conventional and innovative technologies and cleanup processes were evaluated. Following DOE Guidance, representative cleanup processes were selected for development of remedial alternatives. Figure ES-2 presents the technologies and processes selected for development of remedial alternatives. This approach allows DOE the ability to retain the most appropriate processes throughout the entire remedy implementation process, yet provides the flexibility to select specific processes during remedial design, when a technical engineering evaluation may determine the best cleanup processes.
Alternatives Development and Screening
BNL's radiological soil cleanup strategy involves removing radiologically-contaminated soils from the other OUs and consolidating them with the Former HWMF soils for treatment or containment. In this way, all radiological soil contamination at BNL can be addressed collectively. With this in mind, nine alternatives were assembled for initial screening using the representative processes presented in Figure ES-2. The components of the alternatives are presented in Table ES-2. Three broad screening criteria prescribed by Environmental Protection Agency Remedial Investigation/Feasibility Study guidance (Effectiveness, Implementability, and Cost) were applied to the nine alternatives to reduce the number of alternatives to six.
Two of the three alternatives (Large-Scale Excavation, Soil Washing, and Off-site Disposal and Large-Scale Vitrification) were deleted during the initial screening primarily because the degree of added treatment effectiveness and protection afforded was not justified by the substantial increase in cost. A third alternative was deleted (Soil Cap) because it did not reduce the risk for Sr-90 migration to groundwater.
A comparison of typical unit costs for the various technologies considered in alternatives development is presented in Table ES-3. This table demonstrates that for each Cs-137 concentration interval evaluated, a range of technologies is applicable at a range of costs.
Comparative Analysis of Alternatives
Six alternatives were retained for detailed evaluation, including:
|Alternative Number||Alternative Description|
|No Action with Monitoring|
|Moderate Excavation, Offsite Disposal, and RCRA Cap|
|Large-Scale Excavation and Off-site Disposal|
|Moderate Excavation, Soil Washing, Off-site Disposal, and RCRA Cap|
|Moderate Vitrification and RCRA Cap|
Table ES-4 presents a detailed comparative analysis of the six alternatives using the seven threshold and balancing criteria prescribed in Environmental Protection Agency guidance for a Remedial Investigation/Feasibility Study.
For each alternative, radiological risk to future users of the HWMF area, and alternative implementation risks to cleanup workers (both radiological and non-radiological) and to the community are quantified in Table ES-5. This facilitates a comparison of the risk reduction benefits (risk to future users) versus the implementation risks for each alternative.
The summary of estimated costs for each alternative is presented in Table ES-6. This analysis includes three elements: capital costs, total operation and maintenance (O&M) present worth costs, and net present worth total costs. All costs have been rounded to four significant figures.
Two factors are included in the Sensitivity Analysis performed on the baseline net present worth costs for the six alternatives subjected to detailed analysis. Brief descriptions follow and the impacts of these sensitivity factors on alternative costs are presented in Table ES-7.
The impact of an increase in the secondary action level from 600 pCi/g to 1200 pCi/g was evaluated. This analysis is presented as Factor 1 in the Sensitivity Analysis in Section 5.8 for Alternatives 3 and 6. The cost for Alternative 3 was reduced by 10%, while the cost for Alternative 6 was reduced by 14%. These cost reductions are attributable to 22% increases in the volumes of soil being capped in each alternative and comparable decreases in the volumes of soil designated for offsite disposal and vitrification, in Alternatives 3 and 6, respectively. Despite the reduced cost associated with doubling the secondary action level, the more conservative secondary action level of 600 pCi/g Cs-137 was used in this feasibility study because of its increased protectiveness of human health and the environment.
A sensitivity analysis of the cost of Alternative 4 (Large-Scale Excavation and Offsite Disposal) was prepared to evaluate the effect of the Former HWMF soil remediation goal on the cost of this alternative. Cost estimates were evaluated for five remediation goals in addition to the goal of 67 pCi/g Cs-137 for soils within the Former HWMF, upon which this feasibility study is based. Figure ES-3 demonstrates the effect of the Former HWMF remediation goal on the cost of soil remediation. The alternate goals ranged from 15 pCi/g Cs-137 to 600 pCi/g Cs-137, and resulted in soil remediation volume increases as high as 46% for 15 pCi/g Cs-137 and volume decreases of approximately 52% for 600 pCi/g Cs-137. The corresponding changes in alternative costs ranged from a cost increase of 38% for 15 pCi/g Cs-137 to a cost decrease of 43% for 600 pCi/g Cs-137.
Alternative 4, Large-Scale Excavation and Off-site Disposal, is selected as the alternative which best addresses the Environmental Protection Agency's evaluation criteria, particularly the threshold criteria: protectiveness of human health and the environment and compliance with Applicable or Relevant and Appropriate Requirements (ARARs).
Under Alternative 4, all soils in the Former HWMF greater than the remediation goal of 67 pCi/g Cs-137, and all soils from other Operable Units greater than their remediation goal of 23 pCi/g Cs-137, would be excavated, stabilized as necessary, and disposed off site in a licensed low-level waste disposal facility. Soils with long-lived alpha contamination from AOC 6 would also be disposed off site at an appropriately licensed facility. The Former HWMF wetland would be reconstructed and revegetated. Also, the Ash Pit would receive a soil cover and the Meadow Marsh Area would be addressed by excavation, off-site disposal, and reconstruction of wetlands.
Institutional controls would include deed restrictions that prevent installation of drinking water wells where groundwater exceeds drinking water standards, and that prohibit excavation of building foundations in contaminated areas exceeding remediation goals. In addition, utilization of the Former HWMF site for residential or agricultural purposes after the 50-year period of Federal institutional control would be prohibited. However, this area would be acceptable for residential use after 100 years. The Former HWMF area will be released in accordance with Federal and State requirements instituted at the time of the release.
Alternative 4 has been selected as the recommended alternative for the following reasons:
1) Protection of Human Health and the Environment (Public Protection): The alternative meets the remedial action objectives for protection of human health and the environment, including protection from direct exposure to the public in the future. No radiologically-contaminated soils will remain on site above the remediation goals. Should a failure of institutional controls occur, risks to a residential family would be greatly reduced to below the acceptable criteria.
2) Protection of Human Health and the Environment (Groundwater Protection): The alternative provides protection of the sole-source groundwater aquifer by eliminating contaminated soils and debris above the remediation goals. This will eliminate the infiltration of precipitation through contaminated soils, most important where Sr-90 is present.
3) Compliance with Applicable or Relevant and Appropriate Requirements: The elements of the alternative can comply with state and federal ARARs during both remediation and post-remediation activities. Any future transfer or leasing of BNL properties will also meet the requirements of section 120 H of the Comprehensive Environmental Response, Compensation and Liability Act to ensure that future users are not exposed to unacceptable levels of contamination.
4) Long-Term Effectiveness: The alternative removes all contaminated soils and debris above remediation goals and is the most effective and permanent solution in the long term. In addition, the period of institutional control needed for the Former HWMF is shorter than for the other alternatives (i.e., 50 versus 100 years).
5) Reduction in Toxicity, Mobility or Volume Through Treatment: Alternative 4 provides a substantial reduction in toxicity, mobility and volume through off-site disposal; however, no treatment is provided.
6) Short-Term Effectiveness: The alternative is effective in the short term because of existing DOE/BNL institutional controls. Exposure to workers during remediation will be adequately addressed through compliance with Occupational Safety and Health Administration and Department of Transportation requirements, DOE Orders, and BNL procedures. The public risks of this alternative will be below the Environmental Protection Agency's target risk range. The short-term impacts and risks of this alternative are outweighed by the long-term benefits of off-site disposal.
7) Implementability: The technologies employed in this alternative are both readily available and implementable.
8) Cost: The present worth cost of this alternative is approximately $24,620,000.
Other alternatives evaluated in this feasibility study do not offer protection of human health and the environment, particularly the sole-source Long Island aquifer, and compliance with ARARs to the extent provided by Alternative 4. In addition, Alternative 4 best addresses other Comprehensive Environmental Response, Compensation and Liability Act balancing criteria, such as long-term effectiveness and implementability, compared to the other alternatives. For these reasons, Alternative 4, Large-Scale Excavation and Off-site Disposal, is the recommended alternative for BNL OU I and Radiologically-Contaminated Soils.
Should new technologies such as soil washing become more practical or cost effective during remedial design or remedial action, such that they could potentially affect how the selected remedy is implemented, the remedy may be modified accordingly.
Table ES-8 summarizes the proposed remedial actions for AOCs evaluated in this feasibility study.