APPENDIX A METHODOLOGY
Introduction
The environmental impact assessment methodologies discussed in this section address the full range of natural and human resources and issue areas pertinent to the continued operations at Pantex Plant. These methodologies are also applicable to the analysis of candidate sites considered for the potential interim storage of pits, as described in chapter 5 of this EIS.
Plant Facilities and Infrastructure
Changes to plant facilities and infrastructure are assessed by comparing the support requirements resulting from the changes in the activity levels at Pantex Plant to projected site infrastructure capacities. These assessments focus on transportation and infrastructure and utilities (including water, wastewater treatment, electricity, and natural gas). Projections of site development plans are used to project site infrastructure conditions. Tables are presented that depict the changes in infrastructure. Where needed, requirements generated by the Proposed Action and Alternatives and mitigation considerations are identified that could reduce impacts due to changes in infrastructure on a site-by-site basis.
Land Resources
Land use changes associated with the changes in the activity levels at Pantex Plant could occur on both the plant site and the surrounding region, and could affect both developed and undeveloped land. The analysis of land use also considers impacts that could result from the activities related to the environmental restoration program and modification of existing facilities or the construction of new facilities on Pantex Plant Site.
The degree to which the alternatives affect future use or development of land at Pantex Plant Site are considered. Land use impacts are assessed based on the extent and type of land that would be affected. The land use analysis also considers potential direct impacts resulting from the incompatibility of land use changes with special-status lands, such as prime and unique farmlands.
Geology and Soils
Geology. Impacts to the geological environment could occur from destruction of or damage to unique geological features and subsidence caused by groundwater withdrawal. The local geology that could affect Pantex Plant operations, including geomorphology, stratigraphy, structural attitude of rocks, and faults and seismicity, are described. The locations of capable faults are identified and an overview of the seismicity of Pantex Plant Site, including the history and significance of earthquakes, along with their intensity and ground acceleration, is presented.
Soils. Soil types at Pantex Plant Site are described. Analysis is provided qualitatively to summarize the potential contaminants of concern in soils at Pantex Plant Site. The analysis describes the potential for contaminating soils and sediments from changing activity levels at Pantex Plant and activities related to the environmental restoration.
Water Resources
The quality and quantity of surface water and groundwater resources are described using available data. Potential effects on surface water and groundwater availability and quality are assessed.
Surface Water. Local surface water resources in the Pantex Plant region and their flow characteristics and relationships are used to describe current conditions. Data used for surface water impact assessments include rates of wastewater discharge from Pantex Plant operations.
The water quality of potentially affected surface water and groundwater is determined by reviewing current monitoring data. Focus is given to parameters that exceed applicable water quality criteria. Surface water quality data and effluent discharge data are compared to U.S. Environmental Protection Agency (EPA) National Pollutant Discharge Elimination System (NPDES) permit and TNRCC Wastewater Discharge Permit limits and requirements for Pantex Plant. The performance of Pantex Plant in complying with the permit requirements is presented. The assessment of water quality impacts from wastewater (sanitary and process) and stormwater runoff qualitatively addresses potential impacts to the receiving waters' minimum or average flow, as available and appropriate.
Floodplains are identified to determine whether any of the continuing or proposed operations or facilities are located within a floodplain.
Groundwater. Groundwater resources are analyzed for effects on aquifers, groundwater usage, and groundwater quality within the Pantex Plant Region of Influence (ROI). The affected environment discussion includes a description of the potentially affected hydrogeologic units. The local aquifers are described in terms of the extent, thicknesses, geologic formations, hydraulic properties, and quality of the groundwater. Groundwater recharge areas are also noted. Total baseline groundwater use at the facility is compiled using the best available data.
Available data on existing groundwater quality conditions are compared to Federal and State groundwater quality standards and DOE-derived concentration guidelines for radionuclides and risk reduction standards. Impacts of groundwater withdrawals from activity levels at Pantex Plant are assessed. Impacts are assessed by the degree to which groundwater quality, drawdown of groundwater levels, and groundwater availability to other users would be affected. Impacts on groundwater quality are based on current and anticipated wastewater discharge rates and applicable permit requirements.
Air Quality
Potential effects on the environment associated with air pollutant emissions from normal operations are evaluated for the current activity levels at Pantex Plant. This is assumed to be equivalent to handling 2,000 weapons per year and includes Burning Ground Upgrade operations. The assessment of air quality impacts includes identification of applicable criteria for assessing impacts, the development of emission inventories, and the estimation of air pollutant concentrations.
The assessment of potential impacts to air quality is based on comparison of effects of the Proposed Action and Alternatives with applicable local, State, or National Ambient Air Quality Standards or the potential exceedance of Prevention of Significant Deterioration increments for PM10 (particulate matter of aerodynamic diameter less than 10 micrometers), sulfur dioxide, or nitrogen dioxide.
Assessment criteria for pollutants include the EPA primary and secondary ambient air quality standards for criteria pollutants and those established by the State of Texas. The more stringent of either the EPA or State standards serve as the assessment criteria. The assessment criteria for toxic pollutants include guidelines or standards adopted or proposed by the State of Texas.
Ambient air monitoring data are used to determine maximum background concentrations of pollutants for Pantex Plant Site. Baseline concentrations of pollutants are calculated by modeling site emissions during the baseline year. The baseline concentrations are a conservative estimate of pollutant concentrations at Pantex Plant Site during a period considered representative of recent site activity.
Changes in concentrations of pollutants from the changing activity levels at Pantex Plant are calculated by modeling projected site emissions on an annual basis. Those concentrations are then compared to applicable Federal and State standards for air pollutants to provide an estimate of the potential effects on air quality.
Modeling of site-specific emissions (using the EPA-recommended Industrial Source Complex Short-Term [ISCST2] Model and Long-Term [ISCLT2] Model) was performed in accordance with EPA's Guideline on Air Quality Models (EPA-450/2-78-027R).
Major source criteria and hazardous air pollutant emissions were modeled using actual source locations and stack parameters to determine environmental baseline and criteria pollutant concentrations. Onsite and/or representative National Weather Service meteorological data are used to define the dispersion characteristics of the site.
Acoustics
Acoustic impacts are assessed on the basis of potential degree of change in noise levels at sensitive receptors near the Pantex Plant Site boundary with respect to ambient conditions. The analysis uses available information on the potential types of noise sources and the location of Pantex Plant facilities relative to the site boundary and noise-sensitive locations. The potential for exposure of workers to noise and the measures taken to protect worker hearing are included. Quantitative analysis of blast noise from high explosives detonations is provided using an airblast prediction model called BLASTO.
Biotic Resources
Potential impacts to biotic resources are addressed for the following categories: terrestrial resources, wetlands, aquatic resources, and threatened and endangered species. Changing activity levels at Pantex Plant may affect biotic resources as a result of changes in land use and human disturbance and noise. In general, the potential impacts are assessed based on the degree to which various habitats or species could be affected by the changing activity levels at Pantex Plant. Where appropriate, impacts are evaluated with respect to Federal and State protection regulations and standards.
Terrestrial Resources. Potential impacts to terrestrial resources include loss and disturbance of plant and wildlife habitats. The loss of important or sensitive habitats is considered more important than the loss of a regionally abundant type. Impacts to wildlife are based to a large extent on plant community loss, which is closely associated with animal habitat. The disturbance, displacement, or loss of wildlife was also evaluated in accordance with wildlife protection laws such as the Migratory Bird Treaty Act and Bald and Golden Eagle Protection Act.
Very small concentrations of radionuclides are released to the atmosphere during operations at Pantex Plant. Results of biouptake of radionuclide levels have been identified from monitoring data.
Wetlands. Most impacts from continued operations at Pantex Plant are related to discharge of contaminants to the playas. Other impacts could potentially occur from construction activities conducted outside of wetland areas. No direct loss of wetlands resulting from construction and operation is expected at Pantex Plant Site. Impacts resulting from changing levels of flows are evaluated based on a comparison of expected discharge rates with present stream flow rates.
Aquatic Resources. Aquatic resources could be impacted as a result of sedimentation, increased flows, effluent discharge, and the introduction of thermal or chemical effluents and radionuclides.
Threatened and Endangered Species. Impacts to threatened and endangered species of wildlife and plants, including critical habitat, State-listed species, and species proposed for listing, are determined. A list of species potentially present on Pantex Plant Site is developed using information obtained from the U.S. Fish and Wildlife Service and appropriate State agencies. Impacts are determined in a manner similar to that described for terrestrial and aquatic resources because the sources of potential impacts are similar.
Cultural and Paleontological Resources
Cultural and paleontological resources include prehistoric, historic, World War II, Cold War, Native American, and paleontological resources.
Prehistoric Resources. The affected environment section for prehistoric resources includes a brief overview of the number and types of prehistoric sites at Pantex Plant Site and their status on both the National Register of Historic Places (NRHP) and appropriate State registers. The overview consists of a summary of existing information about prehistoric resources within the site boundary and a discussion of types of sites that are likely to occur.
Impact assessments for prehistoric resources focus mainly on those properties likely to be eligible for the NRHP. Impacts are assessed by considering whether the Proposed Action and Alternatives could substantially add to existing disturbance of resources in the project areas, adversely affect NRHP-eligible resources, or cause loss of or destruction to important prehistoric resources.
Historic, World War II, and Cold War Resources. The affected environment section for historic resources includes a brief overview, the number and types of historic sites at Pantex Plant Site and their status on both the NRHP and appropriate State registers. Impact assessments for historic resources focus mainly on those properties likely to be eligible for the NRHP.
Native American Resources. Native American concerns have been identified through direct consultation with tribal representatives. Impacts to Native American resources are assessed by considering whether the continued operations at Pantex Plant have the potential to affect sites important for their position in the Native American physical universe or belief system.
Paleontological Resources. The affected environment section for paleontological resources includes a description of known paleontological localities and geological formations at Pantex Plant Site that may be fossil bearing. Impact assessments for paleontological resources are based on the numbers and kinds of resources that could be affected as well as the quality of fossil preservation in a given deposit, particularly in deposits with high research potential.
Socioeconomics
This section describes and assesses impacts on local and regional socioeconomic conditions and factors, including population, employment, and income. This EIS assesses the socioeconomic impacts of both changing levels of activity and potential loss of mission at Pantex Plant. Geographically, the potential for socioeconomic effects is greatest in those local jurisdictions that are the residential locations of the majority of Pantex Plant employees. An ROI, comprised of those local jurisdictions likely to experience the greatest socioeconomic impacts, is defined for Pantex Plant. The evaluation of impacts is based on the degree to which changes in employment and population affect the local economy on an annual basis. The following sections discuss each of the socioeconomic conditions and factors considered.
Employment. The changing level of activities at Pantex Plant would affect employment at the plant. Changes in plant employment would, in turn, directly affect local and regional populations and income. Current employment at Pantex Plant is described as well as projected employment associated with changing levels of activity at the plant. Emphasis is placed on evaluating total direct and indirect employment changes and impacts associated with potential mission relocations.
Income. The regional economy surrounding Pantex Plant is characterized. Emphasis is placed on the measurement of the relative contribution and importance of Pantex Plant's employment payroll and purchases to the economy. Changes to local economic conditions are evaluated based on the changing activity levels at Pantex Plant.
Population. The demographic changes in the region surrounding Pantex Plant are described and assessed. Demographic characteristics are presented for the ROI to support the assessment of socioeconomic impacts. Cumulative population impacts include the population impacts of other DOE actions under consideration.
Intrasite Transportation
The focus of this analysis is on the intrasite transfer and handling of hazardous materials at Pantex Plant. The impact analysis emphasizes the radiological effects from the transportation of radioactive materials. This focus is consistent with National Environmental Policy Act guidance and requirements as follows:
- The performance of Pantex Plant-type operations does not require or produce risk-significant quantities in regards to transportation of nonradioactive hazardous materials; therefore, transportation activities involving hazardous materials are small-scale operations that do not have the potential of causing significant damage to the human environment.
- The radiological hazard, not chemical toxicity, is the dominant risk from Pantex Plant-related transportation activities.
The affected environment includes the discussion of frequency and type of movement of materials within the plant boundaries and handling and packaging of materials onsite.
Accidents involving the transportation and handling of radioactive and hazardous material have the potential to lead to human fatalities, excess cancer fatalities, and serious environmental contamination. Normal transport may expose personnel to ionizing radiation. Impact analysis is conducted using Pantex Plant historical records and Safety Analysis Reports. Radiological exposures and excess cancer fatalities are calculated for the workers handling the materials. Impacts to the public outside the Pantex Plant boundaries are not expected from intrasite transfer and handling of radioactive materials.
Waste Management
Wastes generated during the operation of Pantex Plant facilities consist of four primary types: low-level radioactive waste (LLW), low-level mixed waste (LLMW), hazardous waste (HW), and nonhazardous waste.
Pantex Plant provides for the short-term management and onsite storage of wastes, including the means to minimize waste generation, until DOE either disposes of the wastes or places them in long-term storage. To provide a framework for addressing the impacts of waste management for continued operations at Pantex Plant, descriptive information is presented on waste management activities. The volumes of each waste type generated are estimated. These estimates, obtained from the plant, include consideration of concepts for waste minimization. The impact assessment addresses the waste types and waste volumes projected to be generated from the changing activity levels at Pantex Plant. Impacts are assessed in the context of site practices for treatment, storage, and disposal plus the applicable regulatory requirements.
Human Health
Pantex Plant uses a broad variety of processes involving both radioactive and chemical materials that can be hazardous to people who are exposed to them. The degree of hazard is directly related to the types and quantity of the particular radioactive or chemical material to which the person may be exposed. The health effects are determined for the operations at Pantex Plant by identifying the types and quantities of material to which one is exposed, estimating exposures, and calculating the resultant health effects.
The impacts on human health for workers and the public during normal operations and postulated accidents for the various alternatives are assessed. Computer codes are used to simulate the impacts on the health of workers and the public due to normal operations and postulated accidents. These computer codes include: the Melcor Accident Consequence Code System (MACCS) for airborne and liquid radioactive releases where no explosives were involved; and the Explosive Release Atmospheric Dispersion (ERAD) computer code where explosives were involved. Atmospheric dispersion modeling using the ISCST2 Model performed for the air quality analysis is also used in the evaluation of impacts to workers from radiological and hazardous chemicals.
Health Impacts on Plant Workers During Normal Operation. Because radiation workers are individually monitored, experience from past and current operations that are similar to future operations are used to estimate the radiological health impacts to workers. Health impacts from chemicals are discussed qualitatively. Chemical concentrations onsite are compared to published threshold limit values for chemical substances to determine potential human health impacts.
General Health Impacts on the Public During Normal Operation. Public health impacts could result from exposure to radioactive or hazardous chemical materials released during plant operations. The effect is the sum of internal exposure resulting from breathing air, eating food, drinking water, and of external exposure from standing on contaminated ground and being exposed to the air.
Modeling is used to estimate the type and amount of material released and the associated radiological and chemical doses. These doses are converted to health effects using appropriate health risk estimators.
Accident Analysis for Postulated Accident Scenarios. The relative consequences of postulated accidents in the evaluation of each alternative are considered. For the purpose of this assessment, risk is defined as the mathematical product of the probability and consequences of an accident. The specific accidents consider the types and location of facilities. Examples of accidents include those resulting from operator errors, spills, criticality, fire, explosions, common-cause failures, collocated facilities, severe weather, and earthquakes. Transportation and aircraft crash risks are described separately in this EIS.
A risk screening methodology was used to determine the accident scenarios that resulted in the highest combination of frequency and consequence. In all cases, public risk is dominated by the release and dispersion of radionuclides. In those scenarios that involved an explosion, the ERAD computer code was used to model the dispersion and resulting exposure to workers and the public. For nonexplosive scenarios, the MACCS code was used. Results from the computer modeling are radiological doses to the worker and the public. Worker risk is dominated by explosions without an accompanying release of radionuclides (i.e., the greatest risk to the worker is due to high explosive development, manufacture, and testing activities).
In summary, the radiological and hazardous chemical impact estimates presented in this document were obtained by:
- Using the best available data.
- Using state-of-the-art computational tools.
- Considering the processes, events, and accidents that are reasonably foreseeable for Pantex Plant operations.
- Making conservative assumptions when there is doubt about the exact nature of the processes and events taking place.
Aircraft Accidents
A unique and controversial scenario in the accident risk impact assessment is the potential for an aircraft-induced hazardous material dispersal accident. The likelihood and consequence of this accident scenario have been studied extensively since the start of nuclear explosive operations at Pantex Plant, and these studies continue to this day.
At Pantex Plant, data from a Radar Airspace Monitoring System (RAMS) have been utilized to determine the amount, type, and frequency of aircraft movement in proximity to Pantex Plant. The latest DOE Standard methodology (DOE 1996g) is utilized to estimate the likelihood of an aircraft impacting a Pantex Plant facility containing nuclear materials and causing a release (see appendix E). The estimated change in risk, both from the increased storage of components in Zone 4 and from any predicted changes in aircraft operations in proximity to Pantex Plant identified by the Overflight Working Group and committed to by DOE and the Federal Aviation Administration, is discussed.
Human health risks from aircraft-induced radiological releases are assessed using MACCS. The consequence assessment uses such site-dependent factors as meteorology, population distributions, and onsite facility location. The resulting doses are converted to a predicted number of excess cancer fatalities. Air dispersion of radionuclides following an accidental release not explosively initiated is modeled using MACCS, and air dispersion of radionuclides following an accidental release explosively initiated is modeled using the ERAD computer code package.
Intersite Transportation
The intersite transportation assessment focuses primarily on the transport of radioactive material. A transportation baseline, using historical and projected shipment information, is established for evaluating potential environmental impacts. The packaging required for the shipment of pits is described. Risks are calculated for transporting pits and other nuclear weapon components.
The potential environmental impacts of transporting pits and other nuclear weapon components are determined using existing health and accident risk data. For evaluating risk, the following elements are considered: transport mode, weight of material, curies, proximity dose rates (transport index), type of package, number of shipments, and distance.
The Analysis of Dispersal Risk Occurring in Transportation (ADROIT) code is used to evaluate the accident risk posed by the expected transfers of weapons, plutonium, weapons components, and tritium reservoirs. Developed by Sandia National Laboratories for the Defense Programs Transportation Risk Analysis study, the ADROIT code has unique abilities to evaluate the transportation risk from defense program material. This includes the ability to place ERAD data sets within the code for modeling explosively driven events.
Environmental Justice
The potential for disproportionately high and adverse human health or environmental effects on minority and low income populations are evaluated in accordance with Executive Order 12898, Federal Action to Address Environmental Justice in Minority Populations and Low Income Populations. The environmental justice analysis addresses selected demographic characteristics of the Pantex Plant ROI, defined as an 80-kilometer (50-mile) circle centered on Pantex Plant. Similar analyses have also been performed within the ROI for each of the alternate sites considered for interim storage of pits.
The analysis of environmental justice presented in this EIS is based on the definitions of minority and low income populations as contained in the notice for the EPA Office of Environmental Justice (59 FR 192). These definitions call for identification of Census Tracts where 25 percent or more of the persons in 1990 were either minority group members or below poverty level based on their income in 1989. For comparison purposes, definitions of minority and low income populations as provided by the Council on Environmental Quality (CEQ) in August 1995, and also reported in Guidance for Incorporating Environmental Justice Concerns in EPA's NEPA Compliance Analysis (EPA 1996a), are also applied to the 1990 Census data and results of both analysis are reported in the EIS.
Cumulative Impacts
Cumulative impacts include the impacts of continued operations at Pantex Plant combined with impacts associated with other reasonably foreseeable projects that could impact the environment at the plant or in the resource-specific ROIs. Although several DOE programs described in section 1.7 of this EIS have the potential to impact the Pantex Plant ROI, sufficient information for incorporation in this document is currently available for only three programs, the Waste Management (WM), Stockpile Stewardship and Management (SSM), and Storage and Disposition of Weapons-Usable Fissile Materials (S&D) programs. Programmatic EISs (PEISs) have been or are being prepared by DOE for each of these programs.
The WM PEIS examines the environmental impacts of managing radioactive and hazardous wastes at DOE Sites throughout the U.S. Pantex Plant was considered one of 17 "major" sites managing DOE wastes. For Pantex Plant, three types of waste were analyzed: LLMW, LLW, and HW. The WM PEIS analyzes the impacts associated with four management alternatives: No Action, Decentralized, Regionalized, and Centralized. The cumulative impacts of the WM program and the alternatives being considered for Pantex Plant operations in this EIS are discussed in each resource section to the extent information is available from the WM PEIS.
The SSM PEIS considered an alternative in which current Pantex Plant operations could be transferred to another site. This Pantex Plant EIS incorporates by reference and summarizes impacts of relocating operations as identified in the SSM PEIS. It is recognized that relocation of operations would involve a transition period during which relocation would occur in a systematic manner, and activities, such as decontamination and decommissioning and environmental restoration, would be accomplished to prepare the Pantex Plant property for disposal. Because a definite schedule for these transition activities is not yet available, it can only be assumed that employment and consumption of utilities at the plant would decline over several years and no sudden impacts would occur.
The S&D PEIS considers activities that would result in storage of inventories of nonsurplus weapons-usable plutonium and highly enriched uranium (HEU); storage of inventories of surplus weapons-usable plutonium and HEU pending disposition; and disposition of surplus weapons-usable plutonium. For storage, the strategy for long-term storage of weapons-usable plutonium and HEU, as well as the storage site(s), would be decided. For disposition, the strategy and technologies for disposition of surplus weapons-usable plutonium would be decided.
The S&D PEIS is considering Pantex Plant for both storage and disposition alternatives. With the S&D PEIS collocation alternative, construction of new storage facilities would be required to store plutonium and HEU at Pantex Plant. For the disposition alternatives, the emphasis at this stage in the NEPA decision process is on choosing the strategy and technology mix rather than the actual site. The evolutionary Light Water Reactor was chosen for the purpose of analysis as the bounding alternative for disposition. Implementation of this disposition alternative may require the construction and operation of one or more light water reactors, a pit disassembly and conversion facility, a plutonium conversion facility, and a mixed oxide fuel fabrication facility. The bounding alternative also assumes that all of the facilities previously mentioned would be collocated at the same site (potentially Pantex Plant).
The collocation storage alternative and the evolutionary Light Water Reactor disposition alternative from the S&D PEIS are discussed in this Pantex Plant EIS, because those alternatives if they occurred at Pantex Plant, could potentially have the greatest impacts to the Pantex Plant Site. It is important to note that these are conservative bounding impacts. The final S&D PEIS will include an alternative that is a refinement of these storage alternatives. As discussed in sections 1.4 and 1.7.3 of volume I of this EIS, the final S&D PEIS will include an alternative under which pits from Rocky Flats Environmental Technology Site (RFETS) could be transferred to Pantex Plant for storage in Zone 4 as early as 1997. The impacts of this alternative are fully accounted for in this EIS because the pits from RFETS could not cause the total number of pits stored in Zone 4 to exceed the storage limit of 20,000 pits analyzed under the Proposed Action. Furthermore, RFETS pits that could come to Pantex Plant would have the same characteristics, as analyzed in the S&D PEIS, as pits currently or previously stored at Pantex Plant. For disposition, further site-specific tiered NEPA documentation may be required, as appropriate, before any specific site is selected. If different alternatives or a site other than Pantex Plant were selected in the Record of Decision (ROD) (and tiered RODs) for the S&D PEIS, then impacts to Pantex Plant from storage and disposition would be reduced and might not occur.
In addition to the DOE programs, information on other Federal, State, or local projects, including private developments, was sought through contacts with Federal and State regulatory agencies, the Amarillo Economic Development Corporation, the Panhandle Municipal Water Authority, and the City of Amarillo.
This effort yielded only one project (future closure of the Helium Plant) that would contribute to the cumulative impacts in the Pantex Plant ROI. The U.S. Bureau of Mines has been operating the Helium Plant in the Amarillo area since the early 1940s. The Helium Privatization Act of 1996 directs Helium Operations to discontinue production and sale of refined helium by April 1998. The impacts of this action are analyzed in volume I, section 4.11.5, because cumulative impacts of closing or downsizing this facility would be limited to socioeconomic impacts.
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