TABLE OF CONTENTS

ACTION MEMORANDUM

I. PURPOSE

II. SITE CONDITIONS AND BACKGROUND

A. SITE DESCRIPTION

1. Physical Location

2. Removal Site History

3. Release or Threatened Release into the Environment of a Hazardous Substance, or Pollutant or Contaminant

B. ACTIONS TO DATE

1. Previous Actions

2. Current Actions

C. NATIONAL PRIORITIES LIST STATUS

D. PUBLIC COMMENT PERIOD

III. THREATS TO PUBLIC HEALTH OR WELFARE AND THE ENVIRONMENT, AND STATUTORY AND REGULATORY AUTHORITIES

A. THREATS TO PUBLIC HEALTH OR WELFARE

B. THREATS TO THE ENVIRONMENT

IV. PROPOSED ACTIONS AND ESTIMATED COSTS

A. PROPOSED ACTION

1. Proposed Action Description

2. Contribution to Remedial Performance

3. Description of Alternative Technologies

4. Administrative Record

5. Applicable or Relevant and Appropriate Requirements

6. Project Schedule

B. ESTIMATED COSTS

V. EXPECTED CHANGE IN THE SITUATION SHOULD ACTION BE DELAYED OR NOT TAKEN

VI. OUTSTANDING POLICY ISSUES

VII. ENFORCEMENT

VIII. RECOMMENDATION

IX. REFERENCES

X. ACRONYMS

APPENDICES

Appendix A: Groundwater Data from wells downstream of the BLIP facility

Appendix B: Unsaturated Flow Simulation for the Brookhaven Linac Isotope Producer (BLIP)
Viscous Liquid Barrier Demonstration at the Brookhaven National Laboratory,
MSE Technology Applications, Inc. September 1999.

FIGURES

Figure 1 - Regional Site Location Map

Figure 2 - Location of BLIP Facility within the BNL Site

Figure 3 - Location of BLIP Facility and Monitoring Wells

Figure 4 - Cross-Section View of the BLIP Building

Figure 5 - Activated Soil Zone Superimposed on Cross-Section View of the BLIP Building

Figure 6 - Plan View of Activated Soil Zone

I. PURPOSE

The purpose of this Action Memorandum is to document the decision by the U.S. Department of Energy (DOE) to conduct a removal action at the Brookhaven Linear Accelerator Isotope Producer (BLIP) which is designated as sub-Area of Concern (AOC) 16K. The action is part of the Comprehensive Environmental Response Compensation and Liability Act (CERCLA) process for environmental restoration.

The selected removal action alternative is Alternative 4 - "Close Proximity Containment Using Colloidal Silica Grout" - to remediate contaminated soils and prevent additional groundwater contamination. The action involves installation and of a colloidal silica grout, maintenance of the existing cap and continued groundwater monitoring.

This action is being undertaken as a non-time-critical removal action in accordance with the Interagency Agreement between DOE, the U.S. Environmental Protection Agency (EPA) and the New York State Department of Environmental Conservation (NYSDEC) and will be consistent with the final remedial action selected for this AOC. Work will be conducted in accordance with the National Oil and Hazardous Substance Pollution Contingency Plan (40 CFR 300).

II. SITE CONDITIONS AND BACKGROUND

A. SITE DESCRIPTION

1. Physical Location

BNL is located in the geographical center of Suffolk County on Long Island, New York in the Town of Brookhaven (Figure 1). The present site contains 5,265 acres, of which 75 percent are wooded. The remainder is developed and contains office buildings, various large research facilities, parking lots, etc. The BLIP is located in the northwestern section of the BNL property, near the Linear Accelerator (LINAC) and the Alternating Gradient Synchrotron (AGS) ring (Figures 2 and 3).

The BNL site is underlain by approximately 1,600 feet of unconsolidated sediments, which rest on bedrock, and by an aquifer system designated by the EPA as a Sole Source Aquifer, pursuant to Section 1424(e) of the Safe Drinking Water Act. This aquifer system contains the primary sources of drinking water for Nassau and Suffolk Counties. The groundwater table is located approximately 55 feet below the ground surface beneath the BLIP building. South of the building, in the direction of the groundwater flow, the water table is approximately 40 feet below the ground surface.

The BNL site, formerly Camp Upton, was occupied by the U.S. Army in World Wars I and II, and was subsequently transferred to the Atomic Energy Commission in 1947 for use as a national laboratory. BNL carries out basic and applied research in the fields of high-energy nuclear and solid state physics; fundamental material and structure properties and the interaction of matter; nuclear medicine; biomedical and environmental sciences; and selected energy technologies. Major operating facilities include the High Flux Beam Reactor, the Brookhaven Medical Research Reactor, the National Synchrotron Light Source and the Alternating Gradient Synchrotron. BNL is a government-owned, contractor-operated facility of the DOE. BNL is operated and managed by Brookhaven Science Associates (BSA) under contract to DOE.

2. Removal Site History

The BLIP, which is considered an accelerator facility, has operated from 1972 to the present. The facility is a national resource for producing the radioisotopes that are crucial in nuclear medicine for both research and clinical use. The BLIP also supports BNL research on diagnostic and therapeutic radiopharmaceuticals.

The radiological equipment and target handling area for the BLIP are contained in Building 931B. The BLIP is built on an artificial hill that rises to just over 100 feet above mean sea level. The hill is asymmetrical, with the surrounding land to the north, east and west at 85 to 90 feet and to the south at 70 feet.

The target area of the BLIP, the drive assembly and the cooling system are contained in a vertical 34 feet long, 16 inch diameter, stainless steel tube. This tube is filled with 300 gallons of deionized water, to cool the target and provide neutron shielding, and is surrounded by an eight feet diameter tank (Figure 4). The target area extends about 28 feet below the concrete floor of the BLIP facility. There are generally eight targets of different materials. The proton beam generated by the LINAC penetrates the stack of targets but does not reach the soil berm, having been stopped by the targets and the water. However, there is no method at present to prevent activation of the soil near the target as a result of contact with the high-energy secondary neutrons generated in the process.

The BLIP facility also includes an underground double-walled storage tank under Building 931C, used for storing waste water generated by the BLIP while cooling the magnets and targets. This tank is designed in accordance with Suffolk County Sanitary Code Article 12. As part of the BLIP upgrades in 1996, the tank was relocated and reinstalled under the oversight of the Suffolk County Department of Health as tank number 423.

The operation of the BLIP facility over the years has resulted in the activation and radiological contamination of soil located in the vicinity of the BLIP target. Some of the radionuclides are very short-lived but others, particularly tritium and sodium-22, are longer lived and represent a potential for contamination of the groundwater. In February 1988, perceptible losses of cooling water (about four gallons per day) were noted during BLIP operations, resulting in a total loss of 100 to 150 gallons of water. In May 1988, the leak was found to have originated at the primary recirculation pump, which is located within a concrete pit in Building 931B. The contaminants subsequently entered the soil through cracks in the concrete. The leak was repaired and the cracks in the pit patched and sealed. In February 1998, elevated levels of tritium and sodium-22 were noted in monitoring well 064-02, approximately 240 feet downgradient of the BLIP (see Figure 3) and are described in Section 3.

3. Release or Threatened Release into the Environment of a Hazardous Substance, or Pollutant or Contaminant

The primary radioisotopes of concern in the soil berm at the BLIP are tritium, with a half-life of 12.3 years, and sodium-22, with a half-life of 2.6 years. Of the remaining suite of isotopes detected in the soil, beryllium-7, the primary activation product of concern in the cooling water, has a half-life of 53 days. Other isotopes were detected, including iron-55 (half-life 2.7 years) and manganese-54 (half-life 312.5 days), but in smaller concentrations.

The major threat to public health or welfare and the environment from the radioactive contamination in the soil berm comes from migration of the isotopes into the surrounding soils and groundwater, and ultimately into the underlying aquifer.

Additional information concerning the concentrations of the radioisotopes at various locations in the soil berm and the results of modeling estimates indicating the rates of migration and concentration levels over time are contained in the Engineering Evaluation/Cost Analysis Report [CDM Federal, 1999].

B. ACTIONS TO DATE

1. Previous Actions

The BLIP has been in operation from 1972 to the present. During this period, the soil in the immediate vicinity of the BLIP has become activated and contaminated.

In February, 1988, perceptible losses of cooling water were noted during BLIP operations, resulting in a total loss of 100 to 150 gallons of water. In May, 1988, the leak was found to have originated at the primary recirculation pump located within a concrete pit in Building 931B. The contaminants subsequently entered the soil through cracks in the concrete. The leak was repaired, the cracks in the concrete were patched and sealed, and the pit was lined with stainless steel. Soil sampling outside the BLIP indicated that concentrations were below the minimum detection limits for the isotopes of concern (principally, beryllium-7 and tritium). There were no monitoring wells downgradient from the BLIP at that time.

Monitoring well 064-02, south of the LINAC and the BLIP and west of the AGS, has been in use since 1993 and has tracked changes in contaminant levels. In February 1998, elevated levels of tritium and sodium-22 were noted and subsequently confirmed through the installation of 13 additional Geoprobe groundwater samples in that area. The February 1998 monitoring well data revealed the groundwater concentration of tritium to be 14,000 pCi/l and that of sodium-22 43.6 pCi/l, both levels below the drinking water standards (20,000 pCi/l for tritium and 400 pCi/l for sodium-22). However, both values represented significant increases from previously measured values (up to 1400 pCi/l for tritium and up to 27 pCi/l for sodium-22). The maximum tritium concentration detected in the Geoprobes was 53,000 pCi/l in June 1998.

Response actions to these findings included re-routing of downspouts on Building 931B to improve stormwater runoff and drainage in the area; the placement of the gunnite cap over the entire target area to prevent infiltration of rainwater; and the installation of six additional monitoring wells. Also, the BLIP has been identified in the Operable Unit II Remedial Investigation Report [IT 1999] as requiring further action.

Data concerning the nature and extent of soil and groundwater contamination resulting from operation of the BLIP are summarized in the BLIP Engineering Evaluation/Cost Analysis [CDM Federal, 1999]. Recent soil sample data indicate that radiological soil contamination is more widely distributed, both vertically and horizontally, than was originally thought. The full extent of the soil activation will be established through additional sampling as part of the removal action design.

2. Current Actions

Additional investigations of the contaminant levels in the soil in the vicinity of BLIP have occurred. Soil sampling was performed in September 1998 and focused on four Geoprobe locations:

• one directly opposite the beam line within the area of activated soil, to determine the degree of activation
• two near this area, to determine the extent of soil contamination beyond the known activated area
• one outside the building in an area where no radiological contamination was expected.

Samples were collected from four locations at various depths. Generally, little contamination was detected at depths down to 20 feet but then concentrations increased significantly at lower depths. The highest concentration of tritium, 4,020 pCi/g, was found at a depth of 28 to 30 feet, as was that of sodium-22 (42,600 pCi/g). The peak concentrations of other radioisotopes, all found at the same depth, included 73,200 pCi/g (beryllium-7), 8,400 pCi/g (iron-55), 7800 pCi/g (manganese-54), 1840 pCi/g (europium-152), and 1,120 pCi/l (cobalt-60). Non-volatile beta was measured at a peak of 39,900 pCi/g and gross alpha at 765 pCi/l.

Using the soil data and adopting conservative modeling assumptions, it has been estimated that a three-meter high vertical cylinder of contaminated soil would need to be treated to insure that drinking water standards in the aquifer would not exceeded in the future by radionuclides leaching from the contaminated soil. . This cylinder would be centered on the axis of the proton beam and have a radius that extends two meters from the eight-feet diameter tank that houses the BLIP target (Figures 5 and 6). The model predicts that such a cylinder would capture 99.9 percent of the soil activation products.

Possible removal action alternatives for remediation of the contaminated soils were developed and are discussed in the Engineering Evaluation/Cost Analysis [CDM Federal, 1999]. These alternatives were evaluated using appropriate criteria concerning public health and safety protection, effectiveness, feasibility, and cost. The recommended alternative is close proximity containment of the activated soil using an injection of colloidal silica grout. Maintenance of the gunnite cap and monitoring of the groundwater will continue.

C. NATIONAL PRIORITIES LIST STATUS

BNL was added to the EPA's National Priorities List (NPL) in 1989. At that time, BNL was also on the NYSDEC list of Inactive Hazardous Waste Sites. An Interagency Agreement under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), Resource Conservation and Recovery Act (RCRA) and applicable New York State regulations was negotiated between DOE, EPA and NYSDEC and become effective in May 1992. The Interagency Agreement governs the environmental restoration program at BNL. The BLIP Soil Removal Action, included as AOC 16K, is considered a non-time-critical removal action as defined in the National Contingency Plan.

D. PUBLIC COMMENT PERIOD

The BLIP Engineering Evaluation/Cost Analysis Report was issued for public review and comment from September 20, 1999 to October 20, 1999. No comments were received.

III. THREATS TO PUBLIC HEALTH OR WELFARE AND THE ENVIRONMENT, AND STATUTORY AND REGULATORY AUTHORITIES

A. THREATS TO PUBLIC HEALTH OR WELFARE

The potential threats posed by contamination from the operation of the BLIP facility are of a non-time-critical nature. That means no imminent or substantial endangerment to public health, welfare or the environment currently exists at this location that would necessitate remediation within six months. The appropriateness of a removal action is based on the following factor listed in the Code of Federal Regulations [40 CFR 300.415(b)(2)]:

Actual or potential contamination of drinking water supplies or sensitive ecosystems.

The groundwater beneath BNL is designated as a sole source aquifer by the EPA under the Safe Drinking Water Act and is classified Class GA by NYSDEC under New York State Codes, Rules and Regulations Part 703 (6 NYCRR Part 703). The best usage of Class GA groundwater is defined as a source of potable drinking water. The groundwater is the primary source of drinking water in the area and most residents immediately down gradient of BNL are now connected to the public water supply. To date, no contaminants presumed to originate from the BLIP location have been found in groundwater offsite.

B. THREATS TO THE ENVIRONMENT

The major threat to the environment is the contamination of groundwater.

IV. PROPOSED ACTIONS AND ESTIMATED COSTS

A. PROPOSED ACTION

1. Proposed Action Description

The removal action alternative selected to address the activated zone of soil adjacent to the target area of the BLIP involves continued maintenance of the existing gunnite cap and the injection of a colloidal silica grout barrier. The gunnite cap is constructed over the target area to prevent seepage of rainwater. Maintenance of the cap is anticipated to consist of application of asphalt sealer to the cap itself every five years and application of joint sealer to the building perimeter every year. Upon completion of the barrier, an operations and monitoring plan will be developed that outlines the specific activities. The colloidal silica barrier will contain the contaminated region and prevent further leaching to the sole source aquifer. The containment barrier will also act as a beam stop for the duration of research at the BLIP, thus reducing the amount of soil that may undergo spallation from continuing operations at the BLIP facility. Due the low-energy injection method employed, no drill spoils or associated potential work hazards are expected. However, because of the developmental nature of the technology, there is a small degree of uncertainty about the permanency of the containment. Thus a second injection of the silica grout may be needed after 25 years if the facility is in operation at that time.

2. Contribution to Remedial Performance

The Operable Unit II Remedial Investigation Report [February 1999] included sampling and analysis of soils, sediment and surface water, and a baseline risk assessment to determine long-term remediation requirements. The BLIP facility is included in this Operable Unit. The Removal Action contained in this Action Memorandum addresses source and migration control at the BLIP facility and groundwater monitoring. This Removal Action is consistent with the overall site cleanup strategy. The final remedial action will be documented in a future Record of Decision.

3. Description of Alternative Technologies

The alternatives evaluated in the Engineering Evaluation/Cost Analysis Report for the remediation of the activated zone of soil adjacent to the target area of the BLIP included the following:

1. No Action with Institutional Controls
2. Upgrade of Existing Cover
3. Close Proximity Containment Using Cement Grout
4. Close Proximity Containment Using Colloidal Silica Grout
5. Excavation of Activated Soil Zone and Install Beam Stop

Alternative 1 (No Action) would provide some protection to the groundwater via the gunnite and asphalt cap that was installed previously. Groundwater model predictions indicate that the activated soil is unlikely to continue to cause groundwater contamination in excess of drinking water standards if the cover is properly maintained over time. However, concerns regarding effectiveness exist because this alternative does not include the installation of a beam stop, without which soil activation will continue throughout the operational life of the BLIP. The activated soils represent a potential risk to the underlying sole source aquifer, particularly if a cooling system leak should occur.

Alternative 2 (Upgrade of Existing Cover) would provide more protection to the groundwater than Alternative 1 but would not eliminate concerns arising from the absence of a beam stop. That is, soil activation will continue during the operational life of the BLIP and present a risk to the underlying sole source aquifer, particularly in the event of a cooling system leak.

Alternative 3 (Close Proximity Containment Using Cement Grout), together with upgrade of the existing cover, would provide a demonstrated and permanent means of containing the activated soil in the subsurface. Cement grout would adequately contain the activated soil so that contaminants would not leach into the groundwater, in effect permanently stabilizing them. It would also function as a beam stop, thereby eliminating continued activation of the soil during BLIP operations. Against these advantages are three implementability concerns:

• the high pressures needed to inject the grout and the associated vibrations and potential soil compaction;
• the corrections necessary to remedy the damage resulting from high pressure, vibration and soil compaction could lead to potentially high worker exposure and costly schedule delays;
• the large size of the grouting equipment prevents its use within the confines of the BLIP building, thus necessitating some building dismantlement and reassembly.

Alternative 4 (Close Proximity Containment Using Colloidal Silica Grout), together with upgrade of the existing cover, would also provide containment of the activated soil. However, the developmental status of the technology means that the permanency of this type of barrier compared with that of cement grout is not known. The colloidal silica grout remains a gel and does not set like cement grout. Also, because the silica grout may desiccate slowly over time, a second injection may be needed after 25 years to ensure continuation of the containment. As with the cement grout, the silica grout would also act as a beam stop. On the other hand, the implementability problems associated with cement grouting virtually disappear with silica grout injection. The relatively low injection pressures (less than 5 percent of those required to inject cement grout) assure much less associated damage and the equipment can be used within the BLIP structure, removing the problem of building dismantlement and reassembly.

Alternative 5 (Excavation of Activated Soil Zone and Install Beam Stop) is a highly effective removal action but has several implementability and cost concerns. Implementation of a full scale tunneling-type excavation would increase the potential for increased worker exposure to radiologically activated soil and, at the same time, be complicated by the need to consider the presence of underground facilities in unspecified or uncertain locations. This Alternative would also take considerably longer to implement than the other Alternatives, and potentially cause significant disruptions to operations in the BLIP and other nearby facilities. Ultimately, radioactive waste will be generated and require offsite disposal. This would significantly increase the cost of the Alternative compared with those of the other Alternatives and simultaneously add to the risk of exposure to the public during the transportation of the waste to the disposal site.

The EE/CA recommended Alternative 4: "Close Proximity Containment Using Colloidal Silica Grout and Upgrade of the Existing Cover". Subsequent laboratory testing [MSE, 1999] performed after the EE/CA was finalized supports the use of Close Proximity Containment Using Colloidal Silica Grout. In addition, recent groundwater monitoring (see Appendix A) shows significant reduction in the contaminant levels found in the groundwater just south of BLIP. Sampling performed from February 1999 to January 2000 shows tritium levels in wells downstream (20 and 100 feet from the source) of the BLIP facility have fallen off to below detectable levels. This strongly indicates that the existing gunnite cap provides adequate coverage.

Based on the current groundwater monitoring data, it is recommended that the gunnite cap be left in its present configuration. The recommended action now involves the installation of the colloidal silica grout, maintenance of the gunnite cap, and groundwater monitoring. If groundwater monitoring indicates increasing contaminant levels, then the required actions will be reevaluated with the EPA and NYSDEC and the gunnite cap may be upgraded. This alternative reduces contaminant migration to the groundwater; is protective of human health and the environment; and is technically feasible cost-effective.

These remedial actions are consistent with the future use of BNL and are steps toward the overall remediation of the site.

4. Administrative Record

A copy of the Brookhaven LINAC Isotope Producer Engineering Evaluation/Cost Analysis Report [CDM Federal, 1999], is included in the Administrative Record. This Action Memorandum will also be included in the Administrative Record.

5. Applicable or Relevant and Appropriate Requirements

Implementation of Alternative 4 will satisfy Applicable or Relevant and Appropriate Requirements (ARARs), criteria and guidance. The principle ARARs pertaining to the BLIP radiologically-contaminated soils are as follows:

Safe Drinking Water Act (43 USC 300) and National Drinking Water Standards (40 CFR 141). This establishes federal drinking water standards that are relevant and appropriate for establishing goals for groundwater and soil remediation.

New York State Water Quality Standards (6 NYCRR Part 703): This requirement establishes standards of purity for groundwater. Standards for class GA waters are set at the drinking water standards.

Alternative 4 will stabilize the contaminated soils and prevent further leaching of contaminants into the groundwater. Groundwater monitoring will occur to ensure that contaminant levels reduce in time to meet the drinking water standards.

Non-promulgated guidance, also known as To-Be- Considered (TBC) was also evaluated. In that regard, the principle TBC identified for Alternative 4 is DOE Order 435.1 "Radioactive Waste Management". This Order describes the DOE requirements for radioactive waste management at DOE facilities. Radioactive wastes generated during installation of the colloidal silica grout will be disposed of in accordance with this Order.

6. Project Schedule

The proposed removal actions will be performed in accordance with the schedules established under the Interagency Agreement. The key tasks for the BLIP soil remediation include preparation of design specifications and work plans and installation of the colloidal silica barrier. Installation of the barrier is planned for the second quarter in calendar year 2000. The remedial action will be followed by the preparation of a close-out report.

B. ESTIMATED COSTS

The cost of Alternative 4 is estimated to be $591,200.

V. EXPECTED CHANGE IN THE SITUATION SHOULD ACTION BE DELAYED OR NOT TAKEN

A delayed action or no action will increase the potential for increased contamination of the soil and groundwater, and for migration of contaminants to the sole source aquifer. Delayed action will potentially increase the scope and cost of the project.

VI. OUTSTANDING POLICY ISSUES

None.

VII. ENFORCEMENT

The site is owned by DOE. Funding for this action will be provided entirely by DOE and the removal action will be conducted in accordance with CERCLA requirements, the Interagency Agreement, Executive Order 12580 and applicable New York State regulations.

VIII. RECOMMENDATION

This decision document represents the selected removal action for the BLIP radiologically contaminated soil area (AOC 16K) at BNL. These actions were developed in accordance with CERCLA as amended, and are consistent with the National Contingency Plan. This decision is based on information contained in the Administrative Record for the site.

IX. REFERENCES

Note: Administrative Record Citations, where available, are given in parenthesis.

1) [CDM Federal, 1999]. CDM Federal Programs Corporation. " Brookhaven LINAC Isotope Producer Engineering Evaluation/Cost Analysis." September 17, 1999.

2) [IT, 1999]. IT Corporation. "Operable Units II/VII Remedial Investigation Report." February, 1999.

3) [MSE, 1999]. MSE Technology Applications, Inc. Unsaturated Flow Simulation for the Brookhaven Linac Isotope Producer (BLIP) Viscous Liquid Barrier Demonstration at the Brookhaven National Laboratory. Dated September 1999.

X. ACRONYMS

AGS Alternating Gradient Synchrotron

ALARA As Low As Reasonably Achievable

ARAR Applicable or Relevant and Appropriate Requirement

BLIP Brookhaven Linear Accelerator Isotope Producer

BNL Brookhaven National Laboratory

BSA Brookhaven Science Associates

CERCLA Comprehensive Environmental Response, Compensation and Liability Act

CDM CDM Federal Programs Corporation

CFR Code of Federal Regulations

DOE U.S. Department of Energy

EPA U.S. Environmental Protection Agency

LINAC Linear Accelerator

NYSDEC New York State Department of Environmental Conservation

NYCRR New York State Codes, Rules, and Regulations

RCRA Resource Conservation and Recovery Act

Figure 1 - Regional Site Location Map

Figure 2 - Location of the BLIP Facility within the BNL Site

Figure 3 - Location of BLIP Facility and Monitoring Wells

Figure 4 - Cross-section View of the BLIP Building

Figure 5 - Activated Soil Zone Superimposed on Cross-Section View of the BLIP Building

Figure 6 - Plan View of Activated Soil Zone

ND = non-detect

NS = not sampled