5.3 AIR QUALITY
Air pollutant emissions estimates were developed and air dispersion modeling was performed to analyze air quality impacts from the various TWRS alternatives. A detailed description of the sources of emissions, modeling, and results is contained in Volume Five, Appendix G. The analyses were conducted to compare the calculated impacts of potential criteria pollutant releases against National Ambient Air Quality Standards and Washington State Air Quality Standards, the calculated impacts of emissions of toxic and hazardous air pollutants against applicable Washington State regulations, and the calculated impacts of emissions of radionuclides against applicable Federal and Washington State standards.
The various TWRS alternatives would have the potential to emit air pollutants from several locations and from a variety of sources. These sources were depicted in the air dispersion models as either area or point sources. Where the exact source locations were unknown or were expected to move from time to time, area sources were used to stimulate emissions. Air emissions from the vitrification processes would occur from a vertical stack and were modeled as point sources. Emissions from WESF also were modeled as a point source.
5.3.1 Emission Sources
For each alternative described in Section 3.0, emission sources were identified and analyzed. The emissions sources included tank farms, waste retrieval annexes, concrete batch plants, waste processing facilities construction, and waste processing. Figure 5.3.1 shows the source locations used in the modeling scenarios. Figure 5.3.1 contains a legend that identifies the acronyms used to designate the various point and area sources described in the following text.
Tank Farms
Area sources identified as TF1E through TF11E and TF1W through TF6W were assigned to the tanks.
Waste Retrieval Annex Areas
Waste retrieval annexes identified as TA1E, TA2E, TA1W, TA2W, and TA3W were depicted as area sources in the dispersion models.
Figure 5.3.1 Emission Source Locations
Concrete Batch Plant
A concrete batch plant between the 200 East and 200 West Areas supporting construction activities was modeled as an area source.
In Situ Vitrification Process Stacks
During in situ vitrification operations, off-gases would be treated and released through a stack adjacent to each tank farm. A point source (IS6W) was used to model the highest impact emissions from the process stack.
Borrow Site Excavation
Particulate emissions would result from using heavy equipment to excavate and transport borrow materials from Pit 30 at the same location as the concrete batch plant.
Excavating borrow materials from the Vernita Quarry and McGee Ranch would result in similar particulate matter emissions. Specific emissions estimates and modeling were not performed because particulate matter emissions would be controlled by using wetting procedures and surfactants, resulting in compliance with Federal and State air quality standards.
Processing Facilities Construction
Emissions from constructing the processing facilities for the ex situ alternatives were assigned to an area source (vitrification facility).
Processing Facilities Operations
The majority of the emissions during the processing operation for the ex situ alternatives and the Ex Situ/In Situ Combination 1 and 2 alternatives would occur through processing facility stacks. All stacks were modeled as point sources and are located in the vitrification facility area.
Evaporator
Evaporator emissions during routine operations and waste processing operations were modeled as a point source.
W-314 Project
The anticipated emissions from the W-314 Project were not analyzed because the data available for the project indicated that construction activities would be spread out over various areas and of relatively low intensity compared to construction activities associated with the TWRS alternatives.
Drywell Disposal Facility
The emissions from constructing a drywell disposal facility (DWSF) were represented as an area source.
Capsule Packaging Facility
The emissions from the Overpack and Ship alternative were represented by an area source.
Waste Encapsulation and Storage Facility
Emissions from WESF would occur through a stack and were modeled as a point source.
5.3.2 Emissions Scenarios
The various alternatives would involve emissions from one or more of the emission sources described in Section 5.3.1. Implementing the alternatives would involve an initial period of facility construction, followed by an operating period during which the treatment, transfer, or repackaging processes would occur. Consequently, alternatives would have different phases in which the emissions and calculated impacts were distinctly different. For each alternative, the emissions and calculated impacts from each phase were reported separately. The following sections describe the potential sources of air emissions for each remediation alternative.
5.3.2.1 Tank Waste Alternatives
No Action Alternative (Tank Waste)
The No Action alternative would involve routine radiological and nonradiological emissions from continued operations of the storage tanks and routine operations of the evaporator. Because no remediation or closure activities would occur under this alternative, no change in emissions would occur.
Long-Term Management Alternative
The Long-Term Management alternative would involve routine emissions from the tanks plus emissions from transferring the waste to newly constructed DSTs 50 and 100 years in the future. Because no remediation activities and no closure activities would occur under this alternative, no short-term changes in emissions would occur. Fifty years from the present, new tanks would be constructed in the same location as the area reserved for the process facility for the ex situ alternatives. Construction emissions for new DSTs were modeled by assigning them to the source PROC. Increased emissions from tanks undergoing retrieval were analyzed by assigning the highest emission rate for each pollutant to the TF6W Tank Farm.
In Situ Fill and Cap Alternative
Implementing the In Situ Fill and Cap alternative would involve construction and gravel-filling operations at the tank farm locations and removing gravel from Pit 30. Construction activities were assumed to simultaneously occur with filling operations and routine emissions from the continued operations of the tank farms. The following summarizes the pollutant emitting activities and sources for this alternative.
- Particulate matter emissions were assigned for Pit 30 (BTCH) (an assumed potential borrow site) .
- Construction equipment emissions were assigned to the most conservative location (TF6W).
- Gravel handling operations were assigned to TF5W.
- Increased tank emissions during filling operations were assigned to TF6W for retrieval operations.
No substantial additional emissions would occur under this alternative as a result of closure activities. As explained previously, heavy equipment operating at the borrow sites would have particulate emissions; however, wetting procedures and surfactants used at the borrow sites would result in compliance with Federal and State air quality standards.
In Situ Vitrification Alternative
Implementing this alternative would involve constructing a tank farm confinement facility and an off-gas treatment facility at each tank farm. Constructing one confinement facility would occur while vitrification processes were occurring at another tank farm. For potential air quality impacts, the highest emission location for construction would be TF6W, and impacts were calculated using this location.
Operating this alternative would release a treated gas stream from a vertical stack. The location for this operation producing the highest impacts was shown to be adjacent to TF6W. Although construction and operation activities would not occur at the same time and at the same location, operational emissions were assigned to this location (IS6W) to provide a conservative analysis.
No substantial additional emissions would occur under the In Situ Vitrification alternative as a result of closure activities. As explained previously, emission control measures would result in compliance with Federal and State air quality standards.
Ex Situ Intermediate Separations Alternative
The construction phase would involve emissions from constructing five waste transfer annexes and two waste processing facilities, and constructing and operating a concrete batch plant to support these operations. Additionally, emissions associated with constructing tank waste retrieval equipment at the tank farms would occur simultaneously.
An analysis was conducted that identified the TF5W and TF6W areas as having the highest combined impacts when construction activities occurred simultaneously. This analysis identified the TF5W and TF6W areas as having the highest combined impacts. Accordingly, construction impacts were assessed by assuming simultaneous construction operations at the process facilities, concrete batch plant, five transfer annexes (TA1W, TA2W, TA3W, TA1E, TA2E); and two tank farm locations (TF5W and TF6W).
Operating the Ex Situ Intermediate Separations alternative would include separating the waste into HLW and LAW streams and processing the streams at separate facilities. Additionally, retrieval equipment would operate at various tank farm locations during the course of processing. Therefore, the impacts of the operation phase of the alternative were analyzed by evaluating the simultaneous operations of both processing facilities (ST-L and ST-H) and the two tank farm locations producing the highest impacts (TF5W and TF6W).
For all of the ex situ alternatives (Intermediate Separations, No Separations, and Extensive Separations), no substantial additional emissions would occur as a result of future closure activities. As explained previously, emission control measures used with heavy equipment and at the borrow sites would result in compliance with Federal and State air quality standards.
Ex Situ No Separations Alternative
The emissions for the Ex Situ No Separations alternative would differ from the Ex Situ Intermediate Separations alternative because the tank waste would not be separated into LAW and HLW components, and only one processing plant with one process stack would be operated. Two options, vitrification and calcination, were analyzed for this alternative. With the exception of the emission rates of nitrogen oxides and carbon-14, the sources and emission rates associated with the calcination option would be nearly identical to those of the vitrification alternative.
The construction phase would involve emissions from constructing five waste transfer annexes and process facilities, and constructing and operating a concrete batch plant. Emissions from erecting the retrieval equipment at the tank farms would occur simultaneously. These emissions were assessed in the same manner as those for the construction phase of the Ex Situ Intermediate Separations alternative.
Operating emissions would occur at the main process stack at the vitrification facility. Installing and operating retrieval equipment would occur at two tank farm locations at a time during processing. Therefore, the impacts of the operation phase of this alternative were analyzed by evaluating the simultaneous operations of the process facility and the two tank farm locations producing the highest combined impacts (TF5W and TF6W).
No substantial additional emissions would occur as a result of future closure activities under this ex situ alternative.
Ex Situ Extensive Separations Alternative
The construction phase would involve emissions from constructing five waste transfer annexes, the process facilities, and from constructing and operating a concrete batch plant. Emissions from erecting the retrieval equipment at the tank farms would occur simultaneously. These emissions were assessed in the same manner as those for the construction phase of the Ex Situ Intermediate Separations alternative.
Operating this alternative would include separating the tank waste into HLW and LAW streams and processing the streams at separate facilities. Off-gas emissions from these two processes would be combined in a common stack. Retrieval equipment would be operated at various tank farm locations during processing. Therefore, the impacts of the operation phase of this alternative were analyzed by evaluating the simultaneous operations of the process facilities and the two tank farm locations producing the highest combined impacts (TF5W and TF6W).
No substantial additional emissions would occur as a result of future closure activities under this ex situ alternative.
Ex Situ/In Situ Combination 1 and 2 Alternatives
The in situ portion of these alternatives would involve the same source locations and emissions as described for the In Situ Fill and Cap alternative. These emissions would occur simultaneously with those from the operation phase of the ex situ portion of these alternatives.
The construction phases would involve emissions from constructing waste transfer annexes and process facilities, and from constructing and operating a concrete batch plant. Emissions from erecting the retrieval equipment at the tank farms would occur simultaneously. These emissions were analyzed in the same manner as described for the Ex Situ Intermediate Separations alternative.
Operating the ex situ vitrification portion of these alternatives would include separating the HLW and LAW streams and processing the waste at separate facilities. Retrieval equipment would be expected to operate at various tank farm locations during processing. Therefore, the impacts of the operation phase of these alternatives were analyzed by evaluating the simultaneous operations of both process facilities (ST-L and ST-H) and the two tank farm locations producing the highest impacts (TF5W and TF6W).
These alternatives are a combination of two remediation methods, neither of which would produce substantial additional emissions as a result of future closure activities.
Phased Implementation Alternative
Phase 1
The first phase of the Phased Implementation alternative would involve a period during which two vitrification facilities would be built. Construction on both facilities would occur simultaneously, so construction emissions were assigned to a single source (FCPI).
After the first phase of construction was completed, the two facilities would begin operating. Emissions from the vitrification processes would be released through two stacks. The impacts from operations were analyzed by using peak hourly emission rates from all processes simultaneously.
Phase 2
In the second phase of this alternative, a facility would be constructed to treat the remainder of the tank waste. Emissions would come from constructing the five waste transfer annexes, process facilities, and a concrete batch plant. Emissions from erecting retrieval equipment at the tank farms would occur simultaneously. These emissions were assessed in the same manner as described for the Ex Situ Intermediate Separations alternative.
Impacts from operating the second phase of this alternative were assessed in the same manner as for the Ex Situ Intermediate Separations alternative. This involved the simultaneous operation of two facilities and the two tank farm locations producing the highest impacts.
Total Alternative
For the Phased Implementation alternatives, the total impacts would be the result of operating the first phase simultaneously with the second phase. The emissions would occur from operating the combined LAW and HLW plant and the LAW plant from the first phase; plus the emissions from operating the second phase process facilities, the concrete batch plant, the five transfer annexes, and the two tank farm locations producing the highest impacts.
No substantial additional emissions would occur as a result of future closure activities under this alternative.
5.3.2.2 Capsule Alternatives
No Action Alternative (Capsules)
Routine radiological emissions from maintaining the capsules at WESF were analyzed for this alternative and included in the analysis of all other alternatives. These emissions were modeled as a point source.
Onsite Disposal Alternative
Constructing the drywell disposal facility would cause pollutant emissions from construction equipment; therefore, these emissions were modeled as an area source.
Overpack and Ship Alternative
Construction and operation emissions from a repacking facility were modeled as an area source (CPF).
Vitrify with Tank Waste Alternative
No appreciable emissions above those calculated for the Ex Situ Intermediate Separations alternative would occur, so no additional air quality impacts were included in this alternative.
5.3.3 Air Dispersion Models
Version two of the U.S. Environmental Protection Agency (EPA) Industrial Source Complex Model (ISC2) (EPA 1992a) was used for the air dispersion modeling. ISC2 is capable of simulating emissions from diverse source types. ISC2 is a guideline air quality model (accepted by EPA for regulatory applications) and routinely is recommended for performing screening and refined analyses for remedial actions at Resource Conservation and Recovery Act (RCRA) and Superfund sites. The model requires input of source data, meteorological data, and receptor data.
The short-term version of ISC2 (ISCST2) was used to calculate concentrations with averaging periods ranging from 1 to 24 hours. Annual average concentrations and dose values were calculated with the long-term version of the model (ISCLT2).
Source Data
The primary sources of data used for the emission rates were the Engineering Data Packages for the various TWRS EIS alternatives, which were prepared by the Site Management and Operations contractor (WHC 1995a, b, c, d, e, f, g, h, i, n) and the TWRS EIS contractor (Jacobs 1996). The emission rates for each alternative are provided in tables presented in Volume Five, Appendix G.
Long-Term Meteorological Data
The meteorological data used for the ISCLT2 model consists of wind speed, wind direction, and stability class for individual years 1989 to 1993. The data, provided by the Pacific Northwest National Laboratory, were based on measurements collected at the Hanford Meteorological Station (PNL 1994g).
Short-Term Meteorological Data
For short-term averaging periods, the ISCST2 model was run in a screening mode because it adequately calculates the overall impacts and the differences in air quality among the alternatives. A range of meteorological conditions was applied to the model in a manner consistent with EPA guidance (EPA 1992a).
Receptor Data
A receptor is a location where the model calculates specific air quality impacts. The locations of receptors used in the ISC2 model corresponded to areas where workers and the general public could be exposed.
Compliance with Federal and State ambient air quality standards and levels was analyzed using a total of 614 receptors located along the Columbia River, State Route 240, and the Hanford Site boundaries. Receptors were placed at 500-m (1,650-ft) intervals along sections of State Route 240. Other offsite receptors were placed 2 km (1.2 mi) apart.
Compliance with the Federal standard for radionuclide releases (40 CFR 60) was determined by analyzing the effective dose equivalent at the nearest residence (DOE 1994d). No residences are located within 24 km (15 mi) of the 200 West Area or within 16 km (10 mi) of the 200 East Area. Consequently, a circular set of 72 receptors, centered on the 200 West Area and with a 24-km (15-mi) radius, was established. A rectangular grid of 834 receptors that encompasses the Hanford Site was used to generate isopleths of radionuclide impacts.
5.3.4 Results of Air Emission Modeling
The model output consists of calculated ground-level average concentrations. The ISCST2 model was run to determine the maximum 1-hour average concentrations that could result from a range of meteorological conditions. The 1-hour averages were multiplied by correction factors to calculate longer (3-, 8-, and 24-hour) averaging times. Annual average concentrations were produced with the ISCLT2 model.
The results of the modeling were compared with Washington State air quality standards or emission levels. Washington State standards are listed in the Washington Administrative Code (WAC) and include the following:
- Acceptable Source Impact Levels for toxic air pollutants (WAC 173-460);
- Ambient Air Quality Standards for particulate matter (WAC 173-470);
- Ambient Air Quality Standards for sulfur oxides (WAC 173-474);
- Ambient Air Quality Standards for carbon monoxide, ozone, and nitrogen dioxide (WAC 173-475);
- Ambient Air Quality Standards for radionuclides (WAC 173-480); and
- Ambient Air Quality Standards for fluorides (WAC 173-481).
The results also were compared with national primary and secondary Ambient Air Quality Standards listed in 40 CFR 50. The Washington Ambient Air Quality Standards are equal to or more stringent than the National Ambient Air Quality Standards, and thus compliance with the Washington Ambient Air Quality Standards results in compliance with the National Ambient Air Quality Standards.
The modeling results for select pollutants including sulfur oxides, carbon monoxide, nitrogen dioxide, particulates, and total radionuclides are presented in Table 5.3.1. Complete modeling results and comparison to the National Ambient Air Quality Standards and the Washington Ambient Air Quality Standards are presented in Volume Five, Appendix G. The modeling results for all alternatives show no exceedances of Federal or State air quality standards for criteria pollutants, hazardous air pollutants, or radionuclides. The following pollutants would result in the highest levels of emission compared to Federal or State standards.
Carbon Monoxide -- Impacts, as a percentage of the Federal and State 8-hour standard, would occur during the construction phases of the Ex Situ Extensive Separations, Ex Situ Intermediate Separations, and Ex Situ No Separations alternatives (25 percent, 21 percent, and 17 percent, respectively).
Sulfur Oxides -- Impacts, as a percentage of the State 1-hour standard, would occur during the In Situ Vitrification alternative (10 percent of the standard).
Radionuclides -- Impacts, as a percentage of the State annual standard, would occur during the In Situ Vitrification alternative (75 percent of standard, with primary contributors being carbon-14 and iodine-129).
Impacts, as a percentage of the Federal annual standard, would occur during the In Situ Vitrification alternative (24 percent of standard, with primary contributors being carbon-14 and iodine-129).
Table 5.3.1 Major Pollutant Impacts
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