Carl L Jacobson, Charles A. Jones, Mark P. Plessinger
IT Corporation*
Grand Junction, CO 81503

Russel Edge
U.S. Department of Energy-Grand Junction Office
Grand Junction, CO 81503

Joseph E. Virgona
U.S. Department of Energy-Retired
Grand Junction, CO 81503

The U.S. Department of Energy (DOE) has a stewardship obligation following cleanup for 100 sites associated with the nuclear weapons program. Many additional, mostly privately owned, sites such as the Uranium Mill Tailings Radiation Control Act (UMTRCA) Title II disposal cells and possibly the Nuclear Waste Policy Act (NWPA) section 151(b) facilities also will become DOE's responsibility.

Most disposal cells are surface impoundments with engineered covers. Levels of radioactivity isolated in the impoundments (disposal cells) ranges from 4 to 12,330 curies. The purpose of the engineered cover are (1) to limit radon emissions to less than the 20 picocuries per square meter per second standard established at 40 Code of Federal Regulations (CFR) 192 and (2) to limit infiltration of meteoric water so that radioactive and other contaminants are not leached into surrounding ground and surface waters. Disposal cells are situated in a wide variety of climatic regimes from humid temperate in the Eastern United States to semiarid and montane in the Western United States. Most sites are remote, but some are notably urban.

The primary concern of the Long-Term Surveillance and Maintenance (LTSM) Program has been to inspect and maintain the rock or rock-and-vegetation erosion-protection layer on top of the disposal cell to ensure integrity of the disposal cell. Challenges encountered so far include (1) erosion around the base of the disposal cell that threatens side slope stability, (2) biointrusion by deep-rooted plants that penetrate the radon barrier and threaten to increase the saturated conductivity of the barrier, and (3) reduction in the D₅₀ of the crushed rock because of weathering so that the rock is less effective at protecting the cell from a Probable Maximum Precipitation event. Although UMTRCA sites are designed to be essentially maintenance free, it is clear that the LTSM Program will continue to intervene at some of the sites to ensure the long-term integrity of the disposal cell cover.

Transfer of sites to DOE for permanent stewardship involves resolving ownership, rights-of-way, regulatory, and funding issues. Institutional control issues are resolved and a permanent record of key documents is prepared. Stakeholder relationships and reporting requirements are established. When all these tasks have been completed, then a site is fit for transfer.

Remediation and long-term surveillance and maintenance of uranium mill tailings disposal sites are mandated by the Uranium Mill Tailings Radiation Control Act (UMTRCA) of 1978. The act established two types of sites, depending on the status of the sites in 1978 when the act was passed. Title I sites are those that were inactive in 1978. These sites were remediated by the U.S. Department of Energy (DOE) and are legislatively mandated to be completed in 1998. Title II sites are those that were under U.S. Nuclear Regulatory Commission (NRC) licenses in 1978. These sites are to be remediated by private owners to whom the NRC license were issued. Remediation of Title II sites is under way and will continue for several more years. Upon completion of remediation, all Title I sites and most Title II sites will be transferred to the Long-Term Surveillance and Maintenance (LTSM) Program at the DOE's Grand Junction Office (GJO). Implementing regulations at 10 Code of Federal Regulations (CFR) 40 require that the sites be maintained for "1000 years or in no case less than 200 years" to protect human health, safety, and the environment.

The LTSM Program was established in 1989 and assigned to DOE-GJO to provide stewardship for completed low-level radioactive waste disposal sites. As the DOE Headquarters-assigned Center of Excellence for LTSM, DOE-GJO performs the task in accordance with applicable laws, regulatory requirements, agreements, site licenses, and best management practices.

Various materials have been and will be disposed of at sites in DOE-GJO's care. The initial sites in the program, the UMTRCA disposal cells, contain uranium mill tailings and contaminants associated with uranium production, such as heavy metals. Buried equipment, building debris, and asbestos also are co-disposed with the tailings. About one half of the closed disposal cells were constructed to house tailings relocated from floodplains and populated areas. Others were constructed near former mills or tailings ponds that were stabilized in place. Active remediation of ground water contaminated by mill operations is conducted at some sites.

When placed in the UMTRCA disposal cells, materials are isolated from the environment through the use of physical barriers or covers that minimize the emission of radon and the leaching of contaminants. Cell cover designs vary, depending on climatic conditions, and have evolved through lessons learned. Most arid western site covers are multilayered with a radon barrier, frost barrier, bedding layer, and a riprap erosion barrier on top. Some comprise a soil/rock matrix and shallow-rooted plant assemblage for erosion and water intrusion protection. Still others rely solely on thick soil layers (up to 60 feet at Spook, Wyoming) to perform the isolation function.

Entombed research reactors and associated waste materials managed under the Decontamination and Decommissioning (D&D) program were recently accepted into the LTSM Program. Among these are the bioshield and waste from CP-1, the Enrico Fermi-constructed reactor at the University of Chicago.

Ownership of the LTSM sites varies. DOE takes title to most of the UMTRCA sites not already on federal land when they are licensed, although those disposal cells on tribal lands were not transferred to DOE. Title to the D&D sites resides with the Cooke County Forest Preserve in Illinois, a public utility in Nebraska, and a DOE office in Ohio. Permanent access to all sites has been obtained for LTSM use.

DOE's legal responsibility to conduct LTSM is designated in 10 CFR 40 and the NRC-approved site-specific long-term surveillance plans (LTSPs) for the UMTRCA sites. DOE Order 5400.1, General Environmental Protection Program, governs the management practices at some sites, whereas the Comprehensive Environmental Response, Compensation, and Liabilities Act (CERCLA) and consent decrees specify the level of custodial care at others. Ground-water monitoring requirements are specified in LTSPs and are sometimes required by State regulation.

The work scope at individual sites ranges from performing an annual inspection and preparing an inspection report to operating a disposal cell. Environmental monitoring activities may include tracking revegetation efforts, performing radon measurements, and operating leachate collection and treatment systems. Maintenance at most sites has required only replacement of vandalized signs or repair of security fences. However, the natural processes of erosion and aging eventually will necessitate major repairs because, under UMTRCA, isolation of the wastes from the environment must be maintained for "... a thousand years or in no case less than 200 years." Isolation of the wastes from human contact can be as simple as ensuring that the cover riprap is not stolen at remote sites or as difficult as maintaining monitoring systems at urban parks, replacing a damaged cover, or performing large-scale erosion control projects. The LTSM Program also provides disaster response, record keeping, and public information office services.

Many government agencies and private parties help determine DOE's LTSM duties on a site-by-site basis. NRC's requirements are spelled out when LTSPs are approved and the site operations are placed under DOE's general license. Federal, State, and local requirements are stated in environmental permits. Adjacent land owners, rights-of-way holders, former licensees, and tribal representatives also provide frequent input, comments, and demands.

Maintaining the integrity of the disposal cells and the isolation of remnant contamination will be a challenge forever. Degradation of cell covers may be caused by weathering, deep-rooted plant invasion, or erosion. These natural processes are occurring at all sites, but the degradation rates differ because of differences in cover design, construction materials, climate, and native vegetation.

Degradation of the riprap forming the erosion barrier at the Lakeview, Oregon, UMTRCA Title I site has become a concern. The side slopes are protected from wind and water erosion with 3 to 5-inch-diameter riprap. When placed in 1988, rock from the two supply quarries was rated as good and no oversizing was required. However, during construction of the side slopes, crumbling riprap was noted in the quarry stockpile. The stockpile was sampled at several representative locations, and the quality of individual rocks was judged as "good" or "bad." Approximately 5 percent of the rock was judged to be bad, which was consistent with results from the original petrographic analysis of samples obtained from the quarry. Use of this small percentage of bad rock was justified on the basis that the materials had passed the NRC durability criteria for use in frequently saturated areas. To compensate for the small percentage of bad rock, the thickness of the riprap layer was increased to 12 inches-twice the thickness required by design calculations-an acceptable practice at the time. NRC's guidance was changed in 1989; the addition of extra thickness is no longer a valid approach.

Weathering of the rock that had an as-placed D₅₀ size (50 percent passing sieve) of 2.7 to 3.9 inches has been noted during the annual inspections since 1994, and a continuing dialog has been maintained with the NRC regarding the rock's durability. Extrapolation of an abbreviated set of freeze-thaw tests performed by an NRC subcontractor in 1996 indicated that the rock could disintegrate in 300 years. DOE-GJO devised a statistically based screening program and determined an in situ rock size in 1997. The screening showed that the current D₅₀ of the rock is 2.8 inches, which is close to the minimum size of 2.7 inches needed to withstand the Probable Maximum Precipitation (PMP) event. The majority of the riprap is a fine-grained olivine basalt that can be broken with a geologist's hammer while being hand held. Breaking of the rock usually occurs along fractures. To simulate the effects of accelerated aging, representative pieces of riprap were struck once with a geologist's hammer, then screened. A D₅₀ of 2.2 inches resulted.

Deterioration of the Lakeview rock does not now present a threat to human health or to the environment. However, the ease with which the rock can be broken and the rock's low freeze-thaw resistance provide reason to monitor the riprap's condition closely.

As part of the monitoring of the Lakeview site, a test of the effects of root intrusion on the saturated hydraulic conductivity of the radon-infiltration barrier was begun in 1997. The barrier, a compacted soil layer (CSL), was designed to limit the escape of radon and to limit infiltration of water into underlying tailings. Unfortunately, because of the low water-storage capacity of the topsoil, this CSL design favors the growth of deep-rooted plants rather than relatively shallow-rooted plants. Many mature rabbitbrush plants and a few mature sagebrush plants now grow on the top of the disposal cell, and shrub density is expected to increase until it approaches or exceeds population levels (density) observed in native plant communities adjacent to the site.

Preliminary results from tests at two paired (with plants and without) locations suggest that the rabbitbrush and sagebrush plants may have had a subtle effect on the saturated hydraulic conductivity (K_sat) of the radon/infiltration barrier. In both paired tests, K_sat was slightly greater where plant roots penetrated the radon/infiltration barrier. The as-built K_sat for the radon barrier in 1988, according to the completion report, was between 1.0 x 10^-8 and 1.0 x 10^-9 centimeter per second (cm/s), whereas the mean K_sat of the radon barrier in July 1997, as indicated by these preliminary results, was 9.01 x 10^-5 cm/s, or between 4 and 5 orders of magnitude greater. Additional saturated hydraulic conductivity testing of the cell cover is planned for spring 1998 to gain greater spatial coverage.

Saturated hydraulic conductivity tests performed at the Burrell, Pennsylvania, UMTRCA Title I disposal cell in 1996 showed different effects of plant invasion into the radon barrier at this temperate site. Japanese knotwood, a deep-rooted exotic perennial, has proven difficult to control with herbicides and has colonized the Burrell site. Tests performed similar to those at Lakeview showed that, where Japanese knotweed was present, the K_sat of the radon barrier (2.9 x 10^-7 to 3.0 x 10^-5 cm/s) was 2 orders of magnitude greater than in areas without Japanese Knotwood plants. Tests on a nearby analog site with mature vegetation and where the soils have not been disturbed for more than 100 years showed that the barrier's conductivity may eventually increase by 3 orders of magnitude to that of the analog site (1.3 x 10^-4 cm/s).

As a follow-up to the Burrell conductivity tests, a screening-level risk assessment is being performed to determine if the increased influx of water into the tailings presents an unacceptable risk (the Burrell disposal cell contains only 4 curies of ²²⁶Ra). If the calculated risk is as low as expected, the current aggressive application of herbicides will be discontinued, resulting in a cost savings to DOE.

The steps necessary to transfer a site to the LTSM Program for long-term custody depend on the legal or administrative authority under which it is being transferred, current site ownership, and the regulatory authorities for the site. Other considerations include site complexity, monitoring requirements, and the level of risk the site presents to public health, safety, and the environment. Transition plans are negotiated for each site that designate what tasks are necessary and who is responsible to effect transfer.

A generic list of steps to effect site transfer includes

The transferring entity should notify DOE-GJO of its intent to transfer a site 2 years before the expected date of transfer.

The site must be sufficiently remediated to be "fit for transfer" to the LTSM Program. The declaration of fitness for transfer is generally made by the regulatory agency(ies) that have authority over the remediation process. In some cases, DOE will be self-regulating, but a set of remediation goals or standards is required that must be met for a site to be fit for transfer.

A transfer of ownership of the site's real property to the Federal Government may be necessary. Ideally, subsurface mineral rights also will be transferred to the Government. Mineral rights not so transferred must be subordinated to the Government's use of the property.

An LTSP or equivalent operational plan is prepared. This plan describes the actions to be performed by the long-term custodian to meet requirements. The LTSP defines inspection, monitoring, and reporting requirements and identifies the compliance drivers for the required actions.

A funding source for site transfer and/or long-term surveillance and monitoring is established. For sites transferred under the authority of Title II of UMTRCA, a long-term care fee is paid to the U.S. Treasury by the entity transferring the site to DOE. For sites transferred under the authority of Nuclear Waste Policy Act (NWPA), both site transfer costs and a long-term care fee are paid by the transferring entity. For sites already owned by DOE, funding for the site transfer activities is identified by the transferring office; long-term care funds are obtained through the normal appropriations process.

A permanent file for site records is developed. It contains the kinds of information the long-term custodian may need if corrective actions are necessary, or in the event of Freedom of Information Act (FOIA) requests or litigation. Such information includes site characterization data, reclamation plans, design documents, National Environmental Policy Act (NEPA) documentation (e.g., environmental assessments), alternative concentration limit (ACL) applications, site legal descriptions, well completion logs, title documentation, as-built drawings, and photographs.

Outstanding regulatory issues must be identified and, where possible, resolved. The LTSM Program does not want to find itself in the position of having to close out permits, resolve disputes between Federal and State ground-water standards, or resolve outstanding commitments to local stakeholders.

Provision is made for permanent site access. Unless site access is directly from a State or county road, a right-of-way or easement is necessary.

Before site transfer, the LTSM Program will ask that the site be free of unwanted or abandoned buildings, derelict equipment, and trash.

Determination of the long-term care fee is based on the surveillance, monitoring, and maintenance actions required by the legal and regulatory drivers for a site and the best management practices adopted for a particular site-information presented in the site-specific LTSP. DOE-GJO's development of a credible estimate of future long-term care expenses is predicated on historical costs to perform the custodial functions at similar sites.

Key to effecting a satisfactory site transfer is good communication among the involved parties during the 1- to 2-year pre-transfer transition period. At a minimum, involved parties would include DOE-GJO and the transferring entity; additional players might include the NRC, U.S. Environmental Protection Agency (EPA), State and local regulatory authorities, Indian tribes, and other local stakeholders. Once DOE-GJO is notified of the intent to transfer the site, DOE-GJO will want to visit the site and discuss issues with the owner/operator regarding proposed ground-water ACL boundaries, property boundaries, monitor well abandonment, etc.

Experience has shown that the critical path to site transfer typically includes the title clearance/title transfer process. A proactive approach to title clearance is imperative to expediting the transfer process. Even when a site is privately owned in its entirety by the transferring entity, there may be "surprises" that require legal staff time to resolve. A recent transfer was delayed because corporate resources needed to remove internal title issues were tied up by a reorganization.

Institutional controls as defined in 40 CFR 191 can be grouped under two categories: active controls (e.g., site access controls, maintenance operations, control or cleanup of releases from the site, and performance monitoring) and passive controls (e.g., permanent markers, public records and archives, government land ownership, deed restriction, and other methods of preserving knowledge about the location, design, and contents of a disposal site). The LTSM Program employs a combination of both active and passive methods to achieve institutional control.

At Title I UMTRCA sites, ownership of the site by the Federal Government is a legal requirement. Other passive controls include Federal Government acquisition of mineral rights, a permanent granite marker, and public records and archives.

Active institutional controls at UMTRCA sites include annual site inspections, site maintenance as necessary, maintenance of signs that indicate the Government's use or ownership of the property, fencing to control access (at certain sites), and the control or cleanup of releases from the sites, should any occur.

Experience to date with institutional controls has revealed that maintenance is necessary to preserve the viability of some of the controls. Signs are frequently stolen or obliterated by bullet holes and require replacement. Approximately 60 feet of chain-link fence stolen from one of the fenced sites had to be replaced. The most serious maintenance actions to date have been in response to weed control and on-site erosion that could damage disposal site engineered features if left unabated.

DOE-GJO posts a 24-hour telephone number near the official entrance to each site to enable a passersby observing anything to notify a public official ( e.g., police, sheriff) in the event of site damage from vandalism or natural events.

DOE-GJO also establishes a notification agreement with the National Earthquake Information Center in Denver, Colorado. If a local or regional seismic event that exceeds established thresholds occurs, DOE-GJO is notified. Weather events are monitored through the various weather coverage and weather-warning information sites available on the Internet.

When remedial action is complete and a site is ready for transfer to the LTSM Program for long-term inspection, maintenance, and monitoring, DOE-GJO requests copies of certain remedial action project records, which may vary from site to site. Records, or copies of records, to be transferred to DOE-GJO must be identified during the transition period in discussions with the remedial action project staff.

For a typical site, records in the following general categories are likely to be requested:

• Site history (prior to remedial action).
• Regulatory drivers, including Records of Decision and agreements, that define DOE's long-term responsibilities at the site.
• Stakeholder identification (names and addresses of points of contact).
• Legal description of the site, including utility and other easements.
• Preconstruction site characterization reports and baseline data, including data collections and reports on the hydrology and the geology of the disposal site area.
• Description of the ground water model.
• NEPA documents and Finding of No Significant Impact (FONSI).
• Chemical and radiologic characterization of waste material(s) disposed of on site or removed during remedial action [name(s) of contaminants, chemical state(s), volume(s), concentration(s), and level(s)].
• Remedial action plan (RAP) or reclamation plan.
• Construction completion reports, including RAP modifications, quality assurance and quality control field measurements, and as-built drawings.
• Aerial photographs before and after remedial action and final topographic maps, if available.
• Monitoring data and reports prepared during construction and after, but before the date of site transfer (e.g., annual reports to Federal or State agencies and other stakeholders, CERCLA 5-year reviews).
• Completion logs for monitor wells transferred to DOE.
• Access or rights-of-way agreements and leases.
• Applicable permits, such as U.S. Army Corps of Engineers 404 wetlands permit.
• Ground-water ACL applications and supporting documentation.

If records have been maintained by the remedial action project in accordance with DOE and National Archives and Records Administration (NARA) guidelines, the project will likely disposition records according to the project's records management plan or policy. In this case, records transferred to the LTSM Program may be copies of project records if they meet the readability and reproducibility criteria.

Records (or copies of records) selected for turnover to the LTSM Program should be selected with the possibility of FOIA requests, litigation, or additional remedial action clearly in mind. DOE-GJO must have sufficient current and historical records to respond accurately and appropriately.

As the first task in the transfer process, DOE-GJO will request a list that identifies stakeholders such as regulators, other governmental agencies (Federal, State, or local), public interest organizations, and people who have participated previously in the remedial action. DOE-GJO will ask for names and addresses of key people or points-of-contact among these stakeholders.

When a site is transferred to the LTSM Program, DOE-GJO contacts the stakeholders to inform them of the transfer of responsibilities to DOE-GJO and the effective date of the transfer and to provide them with a point-of-contact at DOE-GJO and a brief outline of ongoing activities at the site. The transfer of most sites will be noted by the NRC in the Federal Register. Meetings with stakeholders are arranged when requested by stakeholders or when stakeholder interest warrants a meeting.

To keep stakeholders informed, the LTSM Program often sends annual inspection reports, including monitoring results, to local libraries and public reading rooms. During the preparation of LTSPs, DOE-GJO solicits input from stakeholders. Stakeholders may accompany inspection teams during annual inspections; representatives of States and Indian tribes do this regularly.

DOE is continuing to learn better and less expensive ways to provide the long-term care of its closed sites. Monitoring results have proven useful in the design and maintenance of disposal cells. Working closely with stakeholders has allowed the scientists and engineers performing inspections to reduce costs by two thirds during the last 3 years without compromising the integrity of the sites. Through sponsorship and participation in Government and industry conferences, DOE-GJO shows the need for long-term stewardship and obtains new information resources. Minimizing costs while ensuring that disposed materials remain isolated from the environment will remain the primary challenges to the LTSM Program.

*Work performed under DOE Contract No. DE-AC13-96GJ87335 for the U.S. Department of Energy.