Technical Approach to Groundwater Restoration (TAGR)

Programmatic Environmental Impact Statement For The
Uranium Mill Tailings Remedial Action Ground Water Project

2.0 ALTERNATIVES

This section describes the options (alternatives) for conducting the UMTRA Ground Water Project at the inactive UMTRA Project processing sites and summarizes the comparison of the potential impacts of the alternatives. These impacts are considered in detail in Section 4.0. This section also describes alternatives considered but eliminated from further analysis, site-prioritization methodology, risk assessment methodology, ground water characterization and remediation methods, and waste management methods.

CEQ requires that an environmental impact statement "rigorously explore and objectively evaluate all reasonable alternatives" (40 CFR §1502.14(a)). Reasonable alternatives include those that are practical or feasible from a technical and economic standpoint using common sense, and are not simply desirable from the standpoint of the applicant (51 FR 15618). Reasonable alternatives can be outside the jurisdiction of the lead agency and potentially in conflict with existing federal law. When there are many potential alternatives, a reasonable number of examples covering the full spectrum of alternatives must be analyzed and compared (51 FR 15618).

The simplest strategy is one in which no remediation is required. There are two conditions where this can be used. First, if the tailings have not contaminated the ground water, it already meets the preexisting or background conditions; or if the contamination is limited it may met the numerical EPA standards that are called Maximum Concentration Limits (MCLs); i.e., the contamination is so low that it is below the level allowed by EPA. Second, if the concentrations of certain constituents exceed the numerical EPA levels (the MCLs or background), there are two situations in which the EPA has determined that cleanup is not required. (1) EPA allows the use of Supplemental Standards. One example of Supplemental Standards is where the ground water was of such poor quality prior to the milling operation that removing the tailings-related contamination from the groundwater would not raise the quality of the water such that it would or could be used. (2) EPA allows the use of Alternative Concentration Limits (ACLs). An ACL is a numerical concentration for a contaminant that is higher than the Maximum Concentration Limit in the EPA standards or background, but for which is can be shown that human health and the environment would not be adversely affected in a particular situation. If ACLs are used, the Department must demonstrate that the higher levels of contamination do not pose an excessive health risk.

At the next level is Natural Flushing. Once the surface tailings and other contaminated materials are contained in disposal cells, contamination of the groundwater should greatly diminish. At some of the sites, the natural processes of nature will attenuate the contamination over time. If these natural process can reduce the contamination to an acceptable numerical levels such as MCLs background or ACLs within 100 years, the use of natural flushing is permitted by the EPA standards. Under this strategy the Department must demonstrate through analysis that the constituents will be reduced by natural flushing within 100 years or less. If approved, monitoring will continue and if the natural flushing does not work as predicted, DOE would then have to propose and implement a more active strategy. One element of implementing natural flushing that is permitted by the EPA standards is the use of institutional controls. Institutional controls protect public health by alternative means; for example, government ownership of the contaminated area or State/local restriction on the use of contaminated ground water.

Table 1. Ground water compliance strategies that apply under each alternative

Alternative

Strategy	Proposed action	No action^a	Active remediation to background levels	Passive remediation
Active ground water remediation methods	X		X^b
Natural flushing^c	X			X
No ground water remediation Sites that qualify for supplemental standards^d or alternate concentration limits.^e Sites that meet maximum concentration limits or background levels (no impacts).	X X			X X

^aThe analysis of the no action alternative is required by the CEQ and DOE.

^bActive remediation methods would not be used at sites where contamination does not exceed background and likely would not be used at sites that qualify for supplemental standards based on the existence of limited use ground water.

^cNatural flushing means allowing the natural ground water movement and geochemical processes to decrease contaminant concentrations.

^dSupplemental standards applicable for certain site conditions, as identified in the EPA standards, that are protective of human health and the environment, and may be applied in lieu of prescriptive levels.

^eConcentrations of contaminants that may exceed the maximum concentration limits; or, limits for those constituents without maximum concentration limits. If DOE demonstrates, and NRC concurs, that human health and the environment would not be adversely affected, DOE may meet an alternate concentration limit.

^f"No remediation" at sites that do not exceed maximum concentration limits or background levels is not the same as "no action" because these sites would require activities such as site characterization to show that no remediation is warranted.

Finally, the most complex strategy is Active Remediation. If there is excessive contamination and if natural processes will not attenuate it quickly, active control or removal of the contamination is necessary. The classic approach is to pump the contaminated water and treat it to remove the contamination, but other, newer, more effective technologies may also be possible.

The process of selecting a site-specific strategy includes several steps that are not explicitly required by the current regulations, but will help in selecting the best strategy. One of these is to prepare a Baseline Risk Assessment (BLRA). The BLRA is prepared after initial characterization of a site. It provides a detailed analysis of human and environmental exposures to all of the known contaminants of concern. Risks can then be evaluated to determine the appropriate strategy. Another is the Site Observational Work Plan (SOWP). The SOWP addresses the ground water conditions at a site and documents how DOE will demonstrate compliance with the standards. It includes the various techniques that will be used to further characterize a site and is the basis for making the final recommendation to the regulator. Numerous alternatives were evaluated during the planning stages of the PEIS. Five alternatives, including the proposed action, were included in the published Notice of Intent to prepare the PEIS (57 FR 54374). These alternatives represented a preliminary list; public comment on these and other alternatives was part of prescoping and scoping meetings (DOE, 1994a). As a result of the scoping process and other planning activities, four alternatives, including the proposed action, were selected for analysis in this PEIS. The four alternatives are as follows:

Proposed action-DOE would use a consistent, risk-based decision process to comply with the EPA standards at the processing sites. The DOE would use active, passive, and/or no remediation ground water compliance strategies to meet the EPA ground water standards at the UMTRA Project sites. The site-specific ground water compliance strategies would be based on site conditions, potential risks, and input from the affected tribes, states, and public.
No action-DOE would not conduct the UMTRA Ground Water Project. Contaminated ground water would remain as is, and no further action would be made to protect human health and the environment.
Active remediation to background levels-DOE would use a combination of active remediation strategies at most sites to clean up ground water quality to as close to background levels as possible and meet the EPA ground water standards.
Passive remediation-DOE would use natural flushing or no other remediation strategies, including application of alternate concentration limits and supplemental standards, to meet the EPA ground water standards.

These four alternatives are discussed in detail in Sections 2.1 through 2.4. The EPA ground water standards are described in Section 1.4.1. The potential programmatic impacts of implementing the proposed action and alternatives are provided in Section 4.0.

This PEIS differs substantially from a site-specific environmental impact statement because multiple ground water compliance strategies, each with its own set of potential impacts, could be used to implement all the alternatives except the no action alternative. In a traditional environmental impact statement, the identification of alternatives leads directly to an impacts analysis. On the other hand, an impacts analysis for implementing alternatives in this PEIS involves an intermediate step of evaluating a ground water compliance strategy or strategies, the use of which would result in site-specific impacts. This PEIS impacts analysis assesses the potential impacts of the various ground water compliance strategies, then relates them to the alternatives to compare impacts.

2.1 PROPOSED ACTION (Preferred Alternative)

The proposed action, which is DOE's preferred alternative, would select a ground water compliance strategy tailored for each site to achieve conditions that are protective of human health and the environment. The proposed action would consider the full range of ground water compliance decisions in a step-by-step approach, beginning with consideration of the "no remediation" strategy and proceeding, if necessary, to the passive strategy, such as natural flushing with compliance monitoring and institutional controls, and to a more complex, active ground water cleanup methods, such as pump and treat or other engineered approaches to cleaning up contaminated ground water. For example, under the proposed action, if a site risk assessment and site observational work plan indicate that the strategy of "no remediation" would be in compliance with the EPA standards and be protective of human health and the environment, a more complex strategy involving active cleanup methods would not be necessary.

The proposed action is intended to establish a consistent risk-based framework for implementing the UMTRA Ground Water Project and determining appropriate ground water compliance strategies at the UMTRA Project former processing sites. The determination of site-specific ground water compliance strategies would take into account site-specific ground water conditions; human and environmental risks; participation of the Tribes, States, and local communities; and cost. This approach is sufficiently flexible to allow for interim actions, such as an alternate water supply systems, should these activities be necessary in order to reduce risk and/or support institutional controls. The proposed action would also allow the consideration of new ground water cleanup methods that become available.

The proposed action uses a logic framework to identify the appropriate ground water compliance strategy or strategies for a site (Figure 2.1). Each step in the decision process considers meeting the EPA standards and the protection of public health and the environment in determining the appropriate strategy to meet ground water protection standards.

The first step in the decision process would be to determine if the uranium processing activities at a specific site have resulted in ground water contamination exceeding background levels or maximum concentration limits (Figure 2.1). If ground water contamination has not exceeded these standards and is not expected to, remediation would not be required.

Figure 2.1
Proposed Action

If ground water has been contaminated by uranium processing activities and the contamination exceeds background levels or maximum concentration limits, the next step would be to determine if compliance with the EPA ground water standards could be achieved by applying supplemental standards based on the existence of limited use ground water. (Refer to Section 1.4.1 for a discussion of supplemental standards.) If limited use ground water were shown to exist and if supplemental standards were protective of human health and the environment, no site-specific remediation would be required. If supplemental standards based on limited use were not protective, the next step would be to determine whether alternate concentration limits would apply. (Refer to Section 1.4.1 for a discussion of alternate concentration limits.) If alternate concentration limits were protective of human health and the environment, alternate concentration limits would be applied. If not, it would be necessary to determine whether the contaminated ground water plume would qualify for supplemental standards based on the criterion that remediation would cause more environmental harm than benefit. At some sites where supplemental standards or alternate concentration limits may be applied, ground water monitoring and institutional controls may be required to ensure that the application of alternate concentration limits or supplemental standards would continue to be protective of human health and the environment. In addition, when limited use ground water applies, supplemental standards "shall ensure that current and reasonably projected uses of the affected ground water are preserved" (60 FR 2854). The use of supplemental standards would be determined on a site-by-site basis and the DOE would abide by the EPA ground water standards when proposing the use of supplemental standards. All proposed supplemental standards would require U.S. Nuclear Regulatory Commission concurrence.

If supplemental standards would not be protective, the next step would be to determine whether natural flushing would bring the contaminated ground water into compliance (i.e., within maximum concentration limits, background levels, or alternate concentration limits) within 100 years. Natural flushing is a ground water remediation strategy by which natural ground water processes result in compliance with the EPA ground water standards. (Refer to Section 1.4.1 for a discussion of EPA standards related to natural flushing.) Natural flushing could be used if it were determined that institutional controls could be implemented, maintained, and enforced during the natural flushing period; that this strategy was protective of human health and the environment; and that all other conditions, as described in Section 1.4.1, are met.

If natural flushing would not be protective, it would be necessary to determine whether natural flushing combined with active remediation methods would meet the EPA ground water standards and would be protective of human health and the environment. If so, this two-part strategy would be implemented. When combined with natural flushing, active remediation methods could be used for a short time to remove the most contaminated ground water that may occur in a restricted area; then natural flushing would be applied. Another option would be to use low-operation and low-maintenance active methods, such as gradient manipulation or geochemical barriers, in conjunction with natural flushing.

Site characterization data may show that natural flushing combined with active remediation would not result in ground water quality that is protective of human health and the environment. That being the case, the next step in the framework would be to determine if active ground water remediation techniques would meet the EPA ground water standards and if so, to implement these techniques. Several methods of active ground water remediation could be used, including gradient manipulation, ground water extraction, and in situ ground water treatment. The active remediation methods could be used individually or in combination with other cleanup methods. Section 2.8 provides details on active ground water remediation methods. If active remediation resulted in compliance with the EPA standards, remedial action would be complete. If these methods did not result in compliance, supplemental standards based on technical impracticability of remediation would be applied, along with institutional controls where necessary.

The proposed action is sufficiently flexible to allow for alternate water systems or interim actions should these activities be necessary in order to reduce risk and/or support an institutional control.

2.2 NO ACTION

The regulations for preparing an environmental impact statement require that the no action alternative be assessed (40 CFR §1502.14(d)), even if the agency is under a legislative mandate to act (51 FR 15618). The analysis of the no action alternative "provides a benchmark, enabling decision makers to compare the magnitude of environmental effects of the action alternatives" (51 FR 15618).

Under the no further action alternative, no further activities would be conducted to comply with the EPA ground water standards at the inactive UMTRA Project processing sites. The UMTRA Surface Project would be completed but the Ground Water Project would be terminated and the contaminated ground water would be left as it is. DOE would not collect ground water data to continue characterization of ground water, no monitoring of contaminated ground water would take place, and no institutional controls would be used.

The no action alternative would comply with the EPA ground water standards only at the site where there is no ground water contamination (the Lowman, Idaho, site).

2.3 ACTIVE REMEDIATION TO BACKGROUND LEVELS

Under this alternative, the DOE would attempt to clean up ground water to background levels at the UMTRA Project processing sites, using active ground water remediation methods. This attempt would be limited by the technology available. Therefore, it may not be possible to restore some contaminated ground water to background levels. In these cases, the DOE would attempt to reduce contamination to levels as closely as possible to background levels. The rationale behind this alternative is that ground water at most of the uranium processing sites was of better quality before the processing activities occurred and that the ground water should be restored to its preprocessing quality. At most UMTRA Project processing sites, implementation of this alternative would require the use of active ground water remediation methods such as gradient manipulation, ground water extraction and treatment, or in situ ground water treatment (active ground water remediation methods are summarized in Section 2.8). Active remediation methods would be used at the UMTRA Project processing sites regardless of the health and environmental effects and regardless of cost and time. Because active remediation methods would be required at most UMTRA Project processing sites, this alternative would likely reduce the potential risks associated with the ground water contamination and would be protective of human health and the environment.

If this alternative were implemented, DOE would meet the EPA ground water standards at the UMTRA Project sites. Active ground water remediation methods would not be used at sites where the ground water quality beneath the site is currently at background levels and likely would not be used at sites that qualify for supplemental standards based on the existence of limited use ground water.

Under the active remediation to background levels alternative, alternate water systems or interim actions could be used should they be necessary to reduce risk and/or to support an institutional control.

2.4 PASSIVE REMEDIATION

The implementation of this alternative would result in the use of only passive remediation strategies to meet the EPA ground water standards. The passive remediation strategies are 1) performing no remediation at sites that meet supplemental standards or alternate concentration limits, or are at background levels or below maximum concentration limits; and 2) relying on natural flushing. This alternative uses site characterization and risk assessments to determine the most appropriate passive remediation strategy for each site. However, risk assessment and other data may indicate that passive remediation strategies alone would not be protective of human health and the environment at all processing sites.

This alternative is distinct from the no action alternative because, as indicated in Section 2.2, under the no action alternative, activities would not be conducted to restore contaminated ground water at the UMTRA Project sites. In addition, the Ground Water Project would be terminated and the contaminated ground water would be left as is. Under the passive remediation alternative, site characterization would take place before the determination of the appropriate ground water compliance strategy. Ground water monitoring would take place where needed. In addition, institutional controls would be used, if necessary to protect human health and the environment.

In general, if this alternative were implemented, DOE would follow the same initial steps as for the proposed action (Figure 2.1). However, the final step for this alternative would be to determine whether natural flushing would result in meeting background levels, maximum concentration limits, or alternate concentration limits. Institutional controls and monitoring generally would be required to restrict access to contaminated ground water (refer to Section 1.4.1 for a discussion of natural flushing and institutional controls). For sites where natural flushing would reduce the concentrations of contaminants to below the standards in less than 100 years and be protective of human health and the environment, the EPA ground water standards would be met.

Under the passive remediation alternative, active remediation would not be conducted at a site, even if compliance with the EPA ground water standards would not be met. At sites that would not meet standards within 100 years, institutional controls and monitoring would be required for more than 100 years. This would result in noncompliance with the EPA ground water standards and may not protect human health and the environment. The passive remediation alternative may not be protective of beneficial uses of the ground water, such as irrigation or livestock watering.

Under the passive remediation alternative, alternate water systems or interim actions could be used should they be necessary to reduce risk and/or to support an institutional control.

2.5 COMPARISON OF ALTERNATIVES

In accordance with CEQ regulations (40 CFR §1502.14), this document compares the four alternatives and summarizes their potential impacts. The comparison of alternatives below summarizes the detailed comparison found in Section 4.4.

The qualitative analysis of potential impacts of the ground water compliance strategies (Section 4.2) and of the no action alternative (Section 4.3) were used to compare the potential impacts of the alternatives (Section 4.4). The assumptions used to compare the alternatives also appear in Section 4.4.

The potential impacts of the alternatives can be divided into short-term and long-term impacts. Short-term impacts are associated with site characterization and the construction of ground water facilities. Long-term impacts are those that could occur if the ground water remediation was not remediated or if ground water remediation took many years.

Short-term potential impacts

The proposed action and the active remediation to background alternative would require site characterization, monitoring, and construction of remediation facilities. The passive remediation alternative would require site characterization and monitoring.

Potential impacts to air quality, noise levels, visual resources, transportation systems, utilities, and energy supplies would occur principally during site characterization and during the construction of ground water remediation facilities for the proposed and the active remediation to background levels alternatives. As indicated in Section 4.4, the alternatives would have little or no impact on these resources due to the short duration and small scale of the ground disturbance activities. Site characterization, construction, and monitoring activities have the potential to disturb sensitive habitats, species, cultural resources, and land use. However, these impacts potentially can be avoided by conducting site characterization and remediation activities in areas away from these resources. In addition, if impacts to these resources occurred, their effects could be mitigated. Therefore, the potential for site characterization and construction activities to adversely affect these resources would be considered relatively minor. Impacts to land use could also occur.

Long-term potential impacts

Based on the analysis in Section 4.0, long-term adverse impacts could arise under the following circumstances:

If the contaminated ground water did not meet EPA standards and was not controlled. This would occur under the no action alternative.

If the ground water compliance strategy were not protective of human health and the environment. This could occur under the passive remediation alternative.

If institutional controls were in place for many years. This could occur under all the alternatives except the no action alternative.

Implementing the no action alternative would not comply with the EPA standards at all UMTRA Project processing sites. As a result, significant long-term adverse impacts to human health and the environment could occur under the no action alternative. For example, the public could be exposed to site-related hazardous contaminants by drinking contaminated ground water or surface expression of ground water, ingesting contaminated livestock and/or plants, or ingesting contaminated fish and/or wildlife. Adverse impacts to wildlife could occur if the contaminants entered the food chain and/or affected sensitive resources such as wetlands or threatened and endangered species.

Potentially adverse impacts would be less likely under the proposed action or the active remediation to background alternative because all UMTRA Project sites would comply with the EPA standards. In addition, surface and ground water monitoring would take place before and during implementation of the proposed action and the active remediation to background alternative to ensure that protective measures could be maintained or implemented, if necessary.

Implementation of the passive remediation alternative also could result in the exposure of humans and the environment to site-related hazardous contaminants. The potential occurrence of such impacts is less than from the no action alternative, but such impacts could occur at sites where hydrogeological data and risk assessments have demonstrated that the use of passive ground water remediation strategies would not be protective of human health and the environment. For example, this could occur at sites where institutional controls are not viable or would not effectively restrict access to contaminated ground water or at sites where the potential ecological risk from contaminated surface expression of ground water (now or in the future) cannot be avoided or prevented with passive remediation strategies. These potential long-term impacts would have a low probability of occurring under the proposed action or the active remediation to background alternatives.

Institutional controls can be used in conjunction with natural flushing for up to 100 years. These controls may need to be used even longer with the passive remediation alternative because contaminant plumes may still exist after 100 years of natural flushing. The use of institutional controls could result in long-term land use and socioeconomic impacts, as discussed in Sections 4.4.6 and 4.4.11. The passive remediation alternative could have the greatest impact in this area, followed by the proposed action, then the active remediation to background alternative.

In summary, the proposed action and the active remediation to background alternatives are most effective at protecting human health and the environment because under these alternatives all of the UMTRA Project sites would comply with the EPA standards. Implementing the proposed action would potentially result in fewer impacts than implementing the active remediation alternative. The proposed action would potentially be more cost-effective because it would use passive remediation strategies such as natural flushing or no remediation at sites where these strategies are shown to be protective of human health and the environment and meet the EPA standards. The active remediation alternative would be the most costly because of its widespread use of active ground water compliance methods. Under this alternative, active methods would be used at sites where active remediation is justified under the proposed action based on site-specific risk assessments. In addition, active remediation would also be used at many sites where no additional risk reduction would occur as a result of active remediation.

2.6 ALTERNATIVES ELIMINATED FROM ANALYSIS

CEQ regulations require that an environmental impact statement 1) evaluate all reasonable alternatives, 2) briefly discuss those alternatives eliminated from detailed impact analysis in the environmental impact analysis, and 3) provide the reasons for their elimination (40 CFR §1502.14(a)).

Reasonableness is defined as practical or feasible from a common sense, technical, and economic standpoint (51 FR 15618). Four alternatives were considered early in the PEIS planning stages but were eliminated from further evaluation. A fifth alternative, use of tribal and state standards, was considered as a result of comments received on the draft PEIS, but was eliminated from further consideration. All these alternatives and the reasons for their elimination are provided in the following subsections.

2.6.1 Delay the UMTRA Ground Water Project

Delaying the Ground Water Project until the Surface Project is completed was not considered a viable alternative because surface remediation is complete at 18 sites and resources have become available to address ground water compliance. To further delay ground water remediation at some of the processing sites may not be protective of human health and the environment.

2.6.2 Use existing data to make Ground Water Project decisions

Under this alternative, no new site characterization or risk assessment data would have been collected at any of the sites. The UMTRA Ground Water Project would have proceeded using only existing data. Existing site characterization data include geologic, hydrogeologic, geochemical, geotechnical, and radiological conditions at the processing sites. These data were collected for the purposes of designing and implementing surface remediation. This information may not have fully characterized ground water conditions, leading to the possibility of making incorrect decisions regarding site-specific ground water compliance; therefore, this alternative was not considered further.

2.6.3 Provide clean water at the point of use

This alternative would have required the DOE to provide an alternate water source at the point of any use in situations where ground water used by humans has become or soon would become contaminated. Clean water sources could have been bottled water, connection to a municipal water supply, or new wells tapping uncontaminated ground water resources. Under this alternative, the DOE would not have complied with EPA standards.

This alternative was considered because it meets the immediate purpose and need of protecting human health and agricultural applications. It was eliminated from detailed study for the following reasons:

A basic assumption in regard to this alternative is that the DOE would provide an alternate water source at the point of human use (e.g., domestic water sources, livestock watering, and/or crop irrigation) but would do nothing to protect the biological communities from the contaminated ground water. Therefore, use of this alternative would not be protective of the environment since contaminated ground water could discharge into rivers, streams, wetlands, and other biological systems. Furthermore, these biological systems would not be monitored so the degree of contamination, if any, would not be known. This raises the possibility of contaminants entering the biological foodchain which could include humans.

The use of this alternative would require ground water monitoring to determine the location of the plume over time and changes in the level of contamination to determine if the plume is nearing points of use not previously protected. In some cases, this monitoring would be needed for a very long period of time because plumes at some of the UMTRA Project sites move slowly.

This alternative would not meet the EPA standards at all sites. In one sense, this alternative would have to continue until the threat to human health no longer exists. The EPA standards stipulate that ground water contaminants must meet the standards within 100 years. Under this alternative, meeting the standards within 100 years may not occur at all sites.

Treatment at the point of use is not excluded from the alternatives analyzed in the PEIS (except no action). If the drinking water (or other beneficial uses) is threatened at a given site during the Ground Water Project, DOE may provide an alternate source.

Treatment at the point of use that includes institutional controls is the same as the passive remediation alternative. Sites that require institutional controls for the passive remediation alternative also would require institutional controls under the treatment at the point of use alternative, so as to reduce the likelihood of using contaminated ground water.

2.6.4 Achieve ground water compliance without a programmatic approach

This alternative would have required the UMTRA Ground Water Project to proceed without a programmatic approach. This would have meant that ground water compliance would have been treated as discrete tasks for each site. Compliance with EPA's ground water standards would have been met at all processing sites. All NEPA and technical documents would have been produced independently of one another. Scheduling of site activities would have been based on preliminary risk prioritization data.

This alternative was eliminated from further analysis because it would have had many variables and the determination of potential environmental impacts would not be meaningful. In addition, it is not consistent with CEQ regulations, which consider related activities a single course of action (for example, the UMTRA Ground Water Project) that must be evaluated in a single impact statement (40 CFR §1502.4(a)).

2.6.5 Use tribal and state standards

Even though the UMTRCA requires DOE to meet the EPA standards, this alternative would require the UMTRA Project to use tribal and state standards, where they exist, rather than EPA standards. Because the UMTRA Project sites are in 10 different states and on or near lands of four different tribes, the UMTRA Project could be subject to 14 different sets of standards administered by 14 different agencies. This approach would be unacceptable because:

The standards for specific constituents likely vary from agency to agency, which could lead to unequal treatment of the sites.

Some agencies may have standards for specific constituents while others may not have a standard for that specific constituent. This could also lead to unequal treatment of the sites.

Jurisdictional problems would likely arise under this alternative. For example, an UMTRA site may be on land under the jurisdiction of one agency, but a contaminated ground water plume may cross the border into the jurisdiction of another agency.

This alternative would likely increase remedial action costs due to the DOE's having to address so many sets of standards.

Preparing site-specific ground water compliance documents and implementing the site-specific ground water compliance strategies would be difficult, given the large number of varying standards that would have to be addressed.

2.7 SITE PRIORITIZATION AND RISK ASSESSMENT

2.7.1 Site prioritization

Site prioritization ensures that appropriate, relevant, and objective considerations are given to each site during planning stages. The cumulative scores of each site are ranked to determine which sites have the greatest urgency for early actions.

The prioritization system developed for the UMTRA Ground Water Project is based on the UMTRA modified Environmental Restoration Priority System which used multiattribute utility analysis to prioritize sites. This system is described in detail elsewhere (DOE, 1991a) and is summarized here.

This prioritization approach was shared in draft with all the affected tribes and states. Comments were rigorously encouraged. The DOE conducted meetings on the application of this prioritization methodology with three states and two tribes.

The six criteria below were used to prioritize the sites; for each UMTRA site, each criteria was scored from 1 to 7. A score of 1 indicates conditions defined by the factor are acceptable, while a score of 7 indicates highly unfavorable conditions.

Population health risk

This criterion is based on annual health risks to potentially affected populations (i.e., populations consuming ground water directly or indirectly). It can be extrapolated from individual risks calculated in ground water risk assessments, or can be determined by using EPA Hazard Ranking Scores for the ground water exposure pathway.

On the population health risk scale, a score of 7 is equivalent to the occurrence or likely occurrence of 10 adverse health effects per year. The scale decreases logarithmically to 1, which signifies an annual population risk of 1 in 10,000,000.

Individual health risk

This criterion is based on increased individual risks over a lifetime from direct or indirect consumption of ground water. These values are calculated from worst-case, point-of-exposure wells. If the water quality in the area is unsuitable for drinking, another pathway (such as crop irrigation or livestock watering) may be calculated.

These risks are based on the EPA's Risk Assessment Guidance for Superfund documents and produce results in the form of a hazard index and carcinogenic risk. These scores are converted to a logarithmic scale of 1 to 7, where 1 signifies an individual lifetime risk of 1 in 10,000,000, and 7 signifies a risk of 1 in 10.

Timing

Timing is an important factor in prioritizing ground water restoration sites because it quantitatively incorporates the current or anticipated use of ground water. Sites where affected ground water is in use should have higher priority than sites where alternate water supplies are abundant, accessible, and inexpensive. This criterion makes the risk estimates more meaningful since it ties them to actual site factors (such as probability of ground water use).

Additionally, hydrologic factors such as aquifer flushing time, contaminant migration rate, or increased plume spread can be incorporated into the timing criterion.

Environmental risk

The baseline environmental risk scores are determined from the product of two factors:

The sensitivity of the environmental resource at risk.

The magnitude of the threat associated with the contaminated ground water.

The definition for sensitivity of resources was adapted from the EPA's Final Hazard Ranking System (40 CFR Part 300) and includes scenic or wild rivers, unique riparian habitats, wetlands, threatened or endangered species, spawning areas, or any critical habitat. The threat to these resources is based on largely qualitative criteria (including criteria for exceedance of ambient water quality and observed contaminant uptake or toxicity in biota) and threats to the population abundance.

Socioeconomic impact

Socioeconomic impact scores are derived from three components:

Public concern.

Cultural/traditional impacts.

Community losses/opportunity costs.

The first factor scores public and political interest. This is significant on the UMTRA Project because many stakeholders are very concerned about ground water restoration.

The second factor, cultural impacts, is significant primarily to tribal sites. It recognizes the spiritual values the Hopis and Navajos associate with their ground water.

The last factor is used to score economic impacts to a community that loses the use of an affected aquifer. This factor relates to the size of the contaminant plume as well as the demand for its use.

Regulatory noncompliance

The primary criterion in this factor was compliance with applicable ground water standards, including tribal or state laws addressing ground water.

After each factor was scored, the scores were weighted as follows: 20 percent for population risk; 30 percent for individual risk; 10 percent for timing factors; 15 percent for environmental impacts; 15 percent for socioeconomic considerations; and 10 percent for regulatory noncompliance.

Sites were assigned to one of five groups based on this prioritization, allowing for flexibility in planning compliance activities. Category I sites with the highest priority are New Rifle, Old Rifle, and Gunnison, Colorado; Tuba City, Arizona; and Riverton, Wyoming. The Gunnison Category 1 classification does not take into account the implementation of the alternate water supply. Category II sites with the next highest priority are Monument Valley, Arizona; Lakeview, Oregon; Shiprock, New Mexico; and Durango, Colorado. Category III sites are Naturita, Slick Rock, and Grand Junction, Colorado; and Green River and Salt Lake City, Utah. Category IV sites are Bowman and Belfield, North Dakota; Canonsburg, Pennsylvania; Falls City, Texas; and Maybell, Colorado. Category V sites are Ambrosia Lake, New Mexico; Mexican Hat, Utah; Lowman, Idaho; and Spook, Wyoming. The UMTRA Ground Water Project site prioritization system took into account the likelihood that exact scores, and therefore priority, may change as additional data are gathered.

The site prioritization groups would be considered when site-specific decisions are being made. Ground water remediation at the sites would be further prioritized based on additional health or environmental risk information. The following factors would be taken into account when determining the risk at a site:

Is the contaminated ground water likely to be used soon?

How much contamination is present?

How toxic is the contaminated ground water?

Can access to the ground water be controlled?

Prioritization is one element of the Ground Water Project. It would be applied objectively to the maximum extent possible.

2.7.2 Site-specific risk assessments

The purpose of the UMTRA Ground Water Project baseline risk assessments is to determine whether there is current use of the contaminated ground water and whether ground water contamination at the former processing sites has the potential to adversely affect public health or the environment. The results of the site-specific baseline risk assessments are or would be used to:

Evaluate potential current and future public health and ecological risks at the sites.

Determine the need for an alternate water supply, based on the potential for adverse human health effects.

Identify additional data, if any, needed to characterize risks at UMTRA sites.

Determine current and potential future land uses at and near the sites.

Inform the public of current and/or future potential public health and ecological risks.

Help determine site-specific ground water compliance strategies.

Determine whether access to ground water should be restricted through the use of institutional controls.

As indicated in Section 2.1 and as shown in Figure 2.1, the proposed action is a health and environmental risk-based approach for implementing the Ground Water Project. The risk assessments and the ground water characterization data would be used to help determine the appropriate ground water compliance strategies that would be implemented at each UMTRA Project site.

The baseline risk assessments have been or will be made available to the public and libraries near the sites. If the risk assessment identified a significant health risk associated with short-term use of ground water near the sites, mechanisms for restricting access to the ground water would be discussed.

Because the baseline risk assessments are being conducted in the early stages of the Ground Water Project, they may be prepared before comprehensive characterization of the contaminant plume is complete at some sites. The baseline risk assessments identify data gaps and recommend additional data collection efforts. After site characterization is completed, risk assessments may be updated, if necessary.

Risk assessments would be used in deciding how to meet the UMTRA ground water protection standards. In developing site-specific ground water compliance strategies under the proposed action, the baseline risk assessments would be used to determine if a given strategy would be protective of human health and the environment. As indicated on Figure 2.1, protection of human health and the environment is considered in the application of all ground water compliance strategies. For example, if supplemental standards based on limited use ground water were considered for a site, the risk assessment would analyze any potential health effects of consuming contaminated ground water, and consider potential adverse effects on other beneficial uses (e.g., agricultural or industrial). The assessment also would address the potential impacts of contaminated ground water on area plant and animal communities. If supplemental standards based on limited use are determined to be protective of human health and the environment and all other requirements can be met, this strategy may be proposed for a site.

Risk assessments also could be used on the Ground Water Project to assess the risks of natural flushing. As indicated in Section 1.4.1, the use of natural flushing is permitted if it would result in meeting background levels, maximum concentration limits, or alternate concentration limits within 100 years; if institutional controls would protect public health and the environment from the contaminated ground water; and if ground water is not currently or projected to become a source of public drinking water. The risk assessment would be an important tool in determining the protectiveness of proposed alternate concentration limits; determining if the public would be protected from exposure to contaminated ground water; determining the potential for contaminated ground water to adversely affect biological resources; and determining if the contaminated ground water could be used as drinking water or for other beneficial uses.

Appendix B describes the human health and ecological risk assessment methodologies used on the UMTRA Ground Water Project.

2.8 GROUND WATER CHARACTERIZATION AND REMEDIATION METHODS

The nature and extent of ground water contamination must be evaluated before a ground water compliance strategy can be determined. The former processing sites must be characterized to the extent necessary to 1) define the physical, chemical, and biological conditions at the sites; 2) identify the sources and extent of contamination related to processing activities; and 3) obtain additional data that will be used with historical data in evaluating potential impacts to human health and the environment. A ground water compliance strategy for a particular site would be selected only after adequate hydrogeological and geochemical characterization is completed. Hydrogeological and geochemical characterization activities would reduce uncertainties to the extent practical, to ensure the compliance strategy selected would be protective of human health and the environment.

At UMTRA Project sites, inorganic contaminants are the principal constituents that have been found in underlying aquifers. Hazardous constituents that have exceeded maximum concentration limits in ground water at UMTRA Project sites include arsenic, cadmium, chromium, lead, molybdenum, nitrate, selenium, radium-226 and -228, net gross alpha, and uranium. Additional metals that do not have maximum concentration limits have exceeded background concentrations at some sites. This section summarizes ground water characterization requirements and processes. These characterization methods may be implemented for all alternatives except the no action alternative. More detailed descriptions of ground water characterization methods are presented in Appendix C.

2.8.1 Site hydrogeologic and geochemical characterization

Ground water characterization

Under the proposed action, ground water characterization for the UMTRA Ground Water Project would be consistent with the requirements of Subpart B and Subpart C of the EPA ground water protection standards. In support of the proposed action, three programmatic documents would provide guidance for ground water characterization and compliance and ensure project continuity and consistency: the Technical Approach to Groundwater Restoration (DOE, 1993a), the Guidance Document for Preparing Water Sampling and Analysis Plans for UMTRA Sites (DOE, 1993b), and the UMTRA Project Technical Assistance Contractor Quality Assurance Implementation Plan for Surface and Ground Water (DOE, 1994b). These documents would also provide guidance for the Ground Water Project if either the active remediation to background or passive remediation alternative became the proposed action. If the no action alternative became the proposed action, these documents would not be used because future work on the Ground Water Project would cease.

The Technical Approach to Ground Water Restoration provides technical guidance for implementing the Ground Water Project. This document addresses the regulatory basis and requirements for ground water compliance, ground water characterization and remediation methodologies, and the requirements for meeting NRC concurrence.

The Guidance Document for Preparing Water Sampling and Analysis Plans for UMTRA Sites provides a consistent technical approach for water sampling and monitoring activities to be performed under site-specific water sampling and analysis plans. The plans would identify and justify specific sampling locations, ground water constituents for analysis, detection limits, and sampling frequency for the ground water and surface water sampling locations.

The Quality Assurance Implementation Plan describes the policy, organization, functional activities, and quality assurance and quality control protocols for environmental characterization. It provides specifications for collecting and analyzing environmental samples and assessing data. It also addresses quality issues associated with data and samples related to geology, hydrology, chemistry, biology, and engineering.

Assuming that one of the PEIS alternatives other than the no action alternative is implemented, the technical guidance in these three programmatic documents would be used to prepare site observational work plans. The site observational work plan would present the initial evaluation of existing information related to each site, a conceptual site model of the hydrogeological and geochemical processes, and additional data needed to adequately characterize the ground water conditions. Further data collection would be of sufficient quality and quantity to support future project planning and the necessary activities associated with the ground water compliance strategy selection and implementation.

The impacts of the proposed ground water compliance strategy would be assessed in site-specific environmental documents. Baseline risk assessments have been prepared for most sites. When relevant and applicable, these assessments would be modified and updated as additional monitoring and site characterization data are obtained. Site-specific remedial action plans would be prepared for sites where an active ground water remediation strategy would be most appropriate, or the Surface Project remedial action plan would be modified.

The observational method would be used during the planning for and collection of site characterization data. The observational method is an approach that would establish a ground water characterization plan and remedial action based on most probable site conditions; identify reasonable variations from those conditions; identify parameters for detecting variations from the most probable conditions during characterization and compliance; and provide plans for addressing potential variations (Peck, 1969). The observational method would be an effective and economical means to manage uncertainties associated with remediating ground water resources.

Examples of currently available data for the UMTRA Project sites include information on hydrogeologic properties, background ground water quality, contaminant sources, hazardous constituents in ground water, and ground water use, value, and alternative supplies. The extent of ground water characterization during the Surface Project depended on the preferred disposal alternative. Processing sites with disposal cells within their boundaries were characterized in greater detail to justify their selection, provide data for disposal cell design, define the extent of surface contamination, and generate a defensible ground water protection strategy for surface remediation that was protective of human health and the environment. The processing sites where surface remediation activities were completed or were in progress before the EPA ground water regulations were issued generally were characterized to a lesser extent.

For processing sites where contaminated materials were or will be removed off the site, characterization efforts consist of defining tailings-related ground water contamination and determining if conditions at the processing site would adversely affect human health and the environment.

Site-specific ground water characterization would require short-term activities on or near the site. To carry out characterization activities, a crew of 10 or fewer people would be on the site temporarily to conduct activities such as drilling monitor wells, constructing access roads, and excavating test pits. Support vehicles and heavy equipment (for example, drilling rigs) may use roads around the site for brief periods. Certain ground water characterization activities would require electrical power. For example, the pumps used for long-term aquifer tests would require a continuous electrical power supply, which could be drawn from a nearby utility line.

2.8.1.1 Hydrogeologic characterization

Hydrogeologic characterization is important in defining the ground water flow system and the extent of contamination related to uranium processing activities at the UMTRA Ground Water Project sites. Hydrogeologic characterization efforts would also be essential in developing and evaluating ground water compliance strategies.

Hydrogeologic characterization would include the following:

A description of the hydrogeologic characteristics of the site and surrounding land.

A determination of aquifer hydraulic characteristics.

The quantity of ground water and the direction of ground water flow.

A determination of ground water recharge and discharge areas that may influence human health and the environment. Ground water discharge areas would include surface water bodies and water supply wells.

The proximity and withdrawal rates of ground water users.

The current and future uses of ground water in the region surrounding the site.

Most hydrogeologic information is obtained from boreholes drilled for the installation of monitor wells. Geophysical methods may also be used to evaluate subsurface hydrogeologic conditions in the vicinity of the UMTRA Project sites. Borehole information and geophysical methods (under the appropriate conditions) can be used to characterize hydrogeologic conditions such as depth to bedrock, presence of sand and clay layers, and fracture zones that may control ground water flow and contaminant migration. Examples of some hydrogeological characterization features are shown in Figure 2.2.

Monitor wells are used for static water level measurements, ground water quality sampling, and aquifer testing (for example, aquifer pumping tests or water displacement tests). Monitor wells would be designed and installed to provide representative ground water quality samples and aquifer test results. Ground water flow patterns and velocities in the vicinity of the sites would be characterized on the basis of ground water elevations obtained from monitor wells and aquifer test data. Hydraulic parameters that describe the way ground water moves through the aquifer (including transmissivity, hydraulic conductivity, and storativity) would be calculated from aquifer test data. Figure 2.3 shows examples of a monitor well and an extraction well.

Ground water models could be used to analyze and predict ground water and contaminant plume movement. Models would be useful in determining points of exposure at land surface, estimating arrival times at specific downgradient locations or points of exposure, and estimating contaminant concentrations at points of compliance or points of exposure. These models would support risk assessments and ground water compliance strategy development.

Ground water models could also be used in remediation activities. For example, models could be used to assess ground water compliance strategies, compare long-term effects of ground water remediation designs, and optimize performance of aquifer remediation systems.

Figure 2.2
Hypothetical Cross Section Of Aquifer Matrix, Perched Ground Water,
And Regional Ground Water

Figure 2.3
Schematic Diagram Of A Monitor Well And An Extraction Well

Site-specific environmental impact statements, environmental assessments, and remedial action plans for the Surface Project have previously described existing and potential future water uses in the vicinity of the processing sites. As the UMTRA Ground Water Project progresses, water uses and alternative supplies would be monitored and addressed as needed.

2.8.1.2 Geochemical characterization

Geochemical characterization is important in defining ground water contaminants related to uranium processing activities and in determining contaminant interactions with the aquifer matrix. Geochemical characterization efforts are essential to developing ground water compliance strategies because the geochemical composition of the aquifer matrix affects the quality of ground water and the rate of contaminant migration.

The scope of geochemical characterization would include the following:

A review of the historical record of chemicals used in the milling operation.

A determination of the source of contamination and its cumulative impact on the ground water quality.

A determination of the contaminated and uncontaminated ground water quality.

A determination of the geochemistry of the sediment or rock that contains the ground water (known as the aquifer matrix material).

Ground water quality

Existing ground water characterization data would be used to determine the need, if any, to collect additional data for ground water characterization and risk assessments. In some cases, additional background and downgradient ground water quality characterization data would be collected to reduce uncertainties in the conceptual risk model.

Background ground water quality is the water quality in an aquifer that would be expected at a site if contamination from the uranium processing had not occurred. Background ground water quality is determined from hydrologically upgradient locations or adjacent areas that have not been affected by uranium processing activities. Some UMTRA Project sites have naturally poor background ground water due to their proximity to uranium ore bodies. An assessment of background ground water quality would provide a comparison for determining the magnitude and extent of ground water contamination caused by processing. At processing sites with surface water in the area, background surface water quality would also be defined upstream. See Appendix B for an expanded discussion regarding the determination of background water quality.

The distribution of hazardous constituents in the unsaturated zone, ground water, and surface water would be defined on the site and downgradient from the processing sites. Figure 2.4 shows an example of a ground water contaminant plume moving downgradient from a processing site. This information would be used to predict contaminant migration for each site, assess risk, and select ground water compliance strategies.

Geochemistry of aquifer matrix material

Through the geochemical processes of dissolution, precipitation, adsorption, desorption, and ion exchange, geochemical interactions between the ground water contamination and the aquifer matrix influence the rate at which chemical elements and compounds migrate through the aquifer (Table 2.1). Therefore, geochemical characterization of the aquifer matrix would allow for more accurate predictions of contaminant migration velocities. Contaminant migration velocity estimates would be critical for selecting natural flushing versus active ground water remediation and for assessing active remediation designs. Therefore, a detailed knowledge of the aquifer matrix chemistry would play an important role in ground water compliance.

Geochemical characterization methods

Water quality would be assessed by collecting and analyzing water samples from ground water monitor wells, springs, seeps, and surface water bodies. Some basic ground water quality characteristics could be determined in the field. Concentrations of major and minor chemical components in the ground water would be determined in the laboratory. Ground water quality would be evaluated using statistical procedures such as those recommended by EPA (EPA, 1989).

The geochemistry of the aquifer matrix material is characterized to determine mechanisms and the nature of ground water constituent interactions with aquifer matrix material. These data could be used in geochemical models to predict interactions and changes in contaminated ground water as it moves downgradient. Where the ground water compliance strategy depended on the aquifer matrix geochemistry, geochemical modeling could be used in conjunction with ground water flow and contaminant transport models to assess contaminant mobility in the ground water and to predict reactions with minerals in the unsaturated and saturated zones.

2.8.2 Ground water remediation methods

Two ground water compliance strategies are described in this section: natural flushing and active ground water remediation. Natural flushing is passive because it does not involve manipulation of ground water flow, quantity, or quality. Natural flushing means letting the natural ground water processes reduce the contamination in ground water. This process is commonly referred to as natural attenuation and often involves some or all of the geochemical processes identified in Table 2.1. To effectively meet EPA standards, natural flushing must reduce contamination to background levels, to maximum concentration limits, or to alternate concentration limits within 100 years. Active remediation methods involve the engineered manipulation of ground water flow, quantity, or quality to achieve ground water quality standards in a specified period of time. Active remediation methods could be used in combination with natural flushing to minimize remediation costs and to expedite remediation.

Figure 2.4
Hypothetical Cross Section Of Ground Water Contamination Plume

Table 2.1 Geochemical processes that control contaminant migration through an aquifer

Process
Definition

Dissolution

The process of dissolving minerals from the aquifer matrix.

Precipitation

The seperation of chemical constituents from ground water to form new minerals on the aquifer matrix.

Adsorption

The adhesion of chemical constituents on minerals within the aquifer matrix.

Desorption

The removal of a chemical constituent from the aquifer matrix by the reverse of adsorption.

Ion exchange

The replacement of adsorbed chemical constituents by constituents in the ground water.

Biological

The process of transforming chemical compounds into different chemical compounds.

Natural flushing

Natural flushing allows the natural ground water movement and geochemical processes (Table 2.1) to decrease contaminant concentrations. EPA ground water standards require that natural flushing must reduce contamination to levels within regulatory limits within 100 years. To select natural flushing at a specified UMTRA Project ground water site, investigations described in Section 2.8.1 would take place to demonstrate its potential effectiveness at achieving EPA ground water standards in 100 years (Figure 2.5). Under Subpart B of the EPA ground water standards, natural flushing may be used if compliance with the standards would occur within a period of 100 years or less; if adequate monitoring and institutional controls were established and maintained throughout the flushing period; if institutional controls resulted in conditions that were protective of human health and the environment; and if the ground water were not currently nor projected to be a drinking water source.

Figure 2.5
Hypothetical Cross Section View Of Natural Fulshing

Active ground water remediation methods

Active ground water remediation includes several methods that could be used in the Ground Water Project. These methods are described in detail in Appendix C and are summarized below.

Gradient manipulation-Gradient manipulation uses either wells or trenches to add water to an aquifer to increase ground water velocity in a specific direction. Gradient manipulation could be used to accelerate the process of natural flushing. Conversely, gradient manipulation could be used to temporarily prevent discharge of a contaminant plume into surface water bodies by creating a hydraulic diversion to contaminated ground water flow. Gradient manipulation could be used in conjunction with natural flushing to decrease concentrations over a unit area at a faster rate and to temporarily prevent the migration of contaminants into areas where ground water was not previously contaminated or where institutional controls cannot be effectively applied.

Contaminant isolation-Ground water contamination sources are the tailings and associated highly contaminated water or adsorbed hazardous constituents in the unsaturated zone above the water table. Zones of highly contaminated ground water below a processing site are the result of the contamination source. Ground water contamination sources could be mitigated or eliminated through engineered measures to control or contain their hazardous constituents.

Hydrologic, geochemical, and reactive barriers could be used to keep a contaminant source from entering the ground water. These technologies could prevent hazardous constituents from migrating into the ground water. In areas of highly contaminated ground water under a former tailings pile, a barrier could be used for more efficient ground water extraction (Figure 2.6). Because of the expense involved, these techniques would be limited to small areas of highly contaminated material or ground water.

Ground water extraction-Ground water extraction controls movement of contaminated ground water and removes it from the aquifer. In many cases, it would be necessary to extract ground water only from the most highly contaminated zones (Figure 2.7). Ground water flow information and ground water hydraulic parameters would be used in conjunction with optimization codes to design the extraction network including well numbers, depths, spacing, and pumping or injection rates. With the aid of ground water models, the time required for the remedial actions could be estimated.

Well systems could be used to extract contaminated ground water for treatment or to create hydraulic barriers to ground water flow and increase the efficiency of extraction. These wells would then be pumped at specified rates to control the movement of contaminated ground water. In some cases, it could be necessary to combine periods of well pumping with periods of no pumping. When pumping has stopped, contaminants can diffuse out of less permeable (fine grain) zones or desorb from the aquifer matrix until equilibrium concentrations are reestablished in the ground water. Subsequent pumping would remove the minimum volume of contaminated ground water at the maximum possible concentration.

Figure 2.6
Low-Permeability To Enhance Ground Water Extraction

Figure 2.7
Hypothetical View Of Ground Water Extraction

In shallow ground water systems, a well point network consisting of closely spaced, shallow wells connected to a pipe with a centrally located suction lift pump could be used. These systems can create an effective hydraulic barrier by capturing contaminated ground water. Well point networks would be used mainly for shallow water table aquifers because the maximum drawdown obtainable by suction lift is limited to approximately 25 feet (ft) (8 meters [m]) at sea level. Because well points are smaller in diameter and shallower than monitor wells, they are simpler and cheaper to install. This method is temporary (i.e., when the pumping is stopped the barrier ceases to function).

The land application option of ground water disposal would use extracted ground water for agricultural irrigation. Extracted ground water would undergo treatment before use as irrigation water when necessary. This option would be used at processing sites located close to agricultural lands. Processing sites with ground water contaminant plumes containing nitrates would be the most likely candidates for this type of water disposal design.

Contaminated ground water treatment-Once contaminated ground water is extracted from an aquifer, it may be necessary to treat it to protect human health and the environment. The need for treating extracted contaminated ground water before it is discharged depends on the concentrations of contaminants in the extracted ground water and the regulations regarding discharge of effluent to the surface and ground water. Once treated, ground water could be discharged to surface water bodies, recharged back into a shallow aquifer, or used as irrigation water for agricultural purposes.

Contaminants in water and wastewater could be removed by physical, chemical, and biological methods. These methods are discussed in detail in Appendix C.

In situ ground water treatment-In situ (in place) treatment uses chemical agents in the affected soil or ground water to degrade, remove, or immobilize the contaminants. It also includes methods for delivering solutions to the subsurface and for controlling the spread of contaminants and chemical agents beyond the treatment zone.

In situ treatment processes are generally divided into three categories: biological, chemical, and physical. In situ bioremediation accelerates or enhances the rate of microbial reactions to transform the contaminants into benign or insoluble compounds. At UMTRA Project sites, in situ treatment could be used to reduce nitrates through denitrification or to remove metals using sulfate. With chemical in situ treatment, specific chemicals are injected into the soil or ground water to degrade, immobilize, or release contaminants that are in the ground water or attached to the soil particles. Physical in situ methods physically change the soil or ground water using heat, electric energy, or other means to immobilize or to expedite the release or movement of contaminants from the soil or water. In most instances, in situ treatment would be combined with aboveground treatment to achieve the most cost-effective treatment at the UMTRA Project sites.

In some cases, geochemical barriers may be effective in eliminating or reducing ground water contamination. A subsurface permeable barrier would be placed to intercept the flow of contaminated ground water for shallow ground water systems. As the ground water passes through the barrier, the contaminants interact with the barrier material and are removed from the ground water by precipitation or adsorption.

2.9 WASTE MANAGEMENT METHODS

Various types of wastes may be generated during ground water characterization, monitoring, and remediation. The UMTRA Project would follow the Technical Approach for the Management of UMTRA Ground Water Investigation-Derived Wastes to manage field-generated wastes from well drilling, well development, sampling, testing, ground water monitoring, and remediation (DOE, 1994c). This report also provides details on the regulatory requirements for managing and disposing of ground water investigation-derived wastes. The information below summarizes this report (DOE, 1994c). When a ground water compliance strategy is determined and has the potential to form waste material, the management and regulation of this waste would be analyzed in the site-specific environmental document.

The proposed action, the active remediation to background alternative, and the passive remediation alternative have the potential of generating the following materials that may be contaminated:

Well development water-Well development water is generated when new wells are drilled for site characterization, installation of a monitoring system, and active remediation field operations. If necessary, well development water would be treated, and either reinjected into the ground water, applied to the land, or transported to an open UMTRA Project cell or other licensed facility for disposal in a manner consistent with UMTRA Project standards and/or DOE orders.

Drill cuttings and drilling muds-Drill cuttings and drilling muds are the soil and rock brought to surface by the drill when drilling a well. These materials are generated during site characterization, installation of a monitoring system, and drilling during active remediation. Drill cuttings and drilling muds would be analyzed and either applied to the land or transported to an open UMTRA Project cell or other licensed facility for disposal in a manner consistent with UMTRA Project standards and/or DOE orders.

Purge water-Purge water is generated prior to ground water sampling. Ground water sampling from wells would occur during site characterization and monitoring. Purge water would be analyzed and either be evaporated, applied to the land, or discharged in a manner consistent with UMTRA Project standards and/or DOE orders.

Sludge and brine-Sludge and brine result from the treatment of contaminated ground water. Sludge and brine could be generated during site characterization or active remediation field operations. Sludge and brine would be analyzed and disposed of at an open UMTRA Project cell or at an alternate disposal site in a manner consistent with UMTRA Project standards and/or DOE orders.

Ground water and soils-Contaminated ground water and soils may be generated during active remediation field operations. If necessary, contaminated ground water would be analyzed and treated. Ground water would then either be reinjected into the ground water, applied to the land, or discharged to a surface water body in a manner consistent with UMTRA Project standards and/or DOE orders. Soils would either be applied to the land or transported to an open UMTRA Project cell for disposal in a manner consistent with UMTRA Project standards and/or DOE orders.

Prior to disposal in an UMTRA Project disposal cell, wastes would be evaluated to ensure they would not compromise the cell design. If the quantity of liquid wastes exceeds the design parameters of a disposal cell, the liquid waste quantity would be reduced. Waste that could not be accommodated in an UMTRA Project disposal cell would be disposed of at a licensed disposal facility.

All these materials would have the potential of being contaminated with constituents typical of uranium mill processing and being considered residual radioactive materials. These materials would be managed in accordance with the requirements of the UMTRCA, the DOE, EPA, and the appropriate Indian tribes and states. Current data from most sites do not suggest contaminated materials from sources other than uranium processing activities would be encountered, although at some sites naturally occurring ore bodies may be encountered. However, all contaminants from non-UMTRA sources, if encountered, would be managed in accordance with the appropriate requirements.

2.10 COST ESTIMATE METHODS

Since a budget must be developed to obtain yearly federal appropriations, assumptions concerning site-specific compliance strategies must be made in advance to derive a cost estimate that will support budget submittals. These assumptions are for budgetary reasons only and in no way indicate that site-specific ground water compliance strategy decisions have been made prior to completion of the PEIS or a site-specific environmental document.

In estimating costs for each of the three strategies (no remediation, natural flushing, and active remediation), certain generic activities are assumed to support all three proposed strategies. However, the duration, complexity, and cost range of these generic activities vary with the type of compliance strategy selected. These activities include 1) preparing baseline risk assessments, site observational work plans (considered part of detailed site characterization), environmental assessments, and remedial action plans or modifications; 2) conducting a limited monitoring program until implementation of a compliance strategy or closeout activity; 3) performing some type of closeout activity, such as a certification report, a modification to the long-term surveillance plan, and/or licensing; and 4) performing program support activities. The cost estimates include escalation and contingency.

Activities for the no remediation compliance strategy would include those listed above plus, in certain cases, additional site characterization, wells, and revisions to the site observational work plans. Activities for the natural flushing compliance strategy would include longer durations of the same activities plus various phases of monitoring (calibration monitoring and verification monitoring) and a longer period to close out the site following verification monitoring and prior to turning the site over to another DOE project for compliance monitoring. Natural flushing also would include institutional controls. In addition to the above, active compliance strategy sites require detailed construction estimates. In developing these estimates, the Project used a software package called the "G-2 Estimator" in conjunction with environmental construction databases based on UMTRA Surface Project experience. All major cost elements were priced separately using historical data and supplier quotes. Cost elements included utility installation, numbers of wells required, collection systems, installation of water treatment plants, plant operations, testing, land application of treated or untreated water, closure, demobilization, and site restoration. The plant size and length of operations were generated on a site-specific basis using current assumptions on technical parameters of the plume, soil, and contaminants.

Each activity was individually reviewed. Cost estimates were developed based on related historical actuals (approximately 10 years on the UMTRA Surface Project), similar experience on other projects, and/or best professional estimates. The activities were then tailored to each site based on such site-specific attributes as the estimated volume of the plume and contaminants present. A critical path method analysis was then used to develop sequential logic for each compliance strategy, since some activities occur concurrently while others are sequential, and then summarized to develop an overall schedule. The overall Project schedule supported development of non-site-specific Project support activities, processes, or deliverables. The non-site-specific cost estimates were allocated against activities each year and combined to develop a total Project cost.

The last step in developing the cost estimates was to apply contingency to the base estimates to cover uncertainties. Acceptance of the proposed strategies used for the federal budgeting exercise accounts for the largest share of the Project's identified contingency. Other uncertainties to the UMTRA Project's estimates include 1) delays in state-share funding; 2) perturbations and delays in federal funding; 3) lack of access to existing site wells or the inability to drill new wells due to lack of access; 4) changes in currently understood plume size and contaminant concentrations; and 5) unknowns. The basis of estimates has attempted to cover a portion of the above risks; however, each time a project estimate is made, the DOE reexamines contingency application.

The basis of estimates for costs is reviewed several times during the fiscal year beginning in January. The estimates are continually reviewed for reasonableness, adaptability to the technical and political environment, and sound estimating practices.