4.8 ACOUSTICS (NOISE)
4.8.1 Affected Environment
This section addresses noise issues at Pantex Plant. The characteristics of sound include parameters such as amplitude, frequency, and duration. The decibel (dB), a logarithmic unit that accounts for large variations in amplitude, is the accepted standard unit measurement of sound. Different sounds have different frequency content.
When measuring sound to determine its effects on the human population, A-weighted sound levels (dBA) are typically used to account for the response of the human ear. A-weighted sound levels represent adjusted sound levels. The adjustments are made according to the frequency content of the sound. Examples of typical A-weighted sound levels are shown in Figure 4.8.1-1.
Figure 4.8.1-1--Comparative A-Weighted Sound Levels.
Another sound scale is the C-weighted scale (dBC). In contrast to the A-weighted scale, the C-weighted scale provides no adjustment to the noise signal over most of the audible frequency range. The C-weighted scale is generally used to measure impulsive noise such as airblasts from explosions, sonic booms, and gunfire.
Noise is usually defined as sound that is undesirable because it interferes with speech, communication, or hearing; is intense enough to damage hearing; or is otherwise annoying. Noise levels often change with time. To compare levels over different time periods, several descriptors were developed that take into account this time-varying nature. These descriptors are used to assess and correlate the various effects of noise on man, including land use compatibility, sleep and speech interference, annoyance, hearing loss, and startle effects.
The day-night average sound level (DNL) (also written as Ldn in equations) was developed to evaluate the total community noise environment. The DNL is the average A-weighted sound level during a 24-hour period with 10 dB added to nighttime levels (between 10:00 p.m. and 7:00 a.m.). This adjustment is added to account for the increased human sensitivity to nighttime noise events. The DNL was endorsed by the Environmental Protection Agency and is mandated by the U.S. Department of Housing and Urban Development, the Federal Aviation Administration, and the Department of Defense for land use assessments.
The DNL is sometimes supplemented with other metrics, primarily the equivalent sound level (Leq). The Leq is the equivalent, steady state level that would contain the same acoustical energy as the time-varying level during the same time interval.
Frequently, statistical values of noise levels are used to describe a time-varying noise measured in dBA. The noise variation is described in terms of the percentage of time a given noise level is exceeded. The Leq values usually used are L10, L50, and L90, the noise levels that are exceeded 10, 50, and 90 percent of the time, respectively. L10 gives an indication of the top end of the level range though it can still be substantially less than the occasional peak (Lmax). L90 corresponds to the background noise level in the absence of nearby noise sources. L50 is the median noise level.
Table 4.8.11 shows how differences in sound magnitudes are perceived. Differences over long timespans, such as before and after a project requiring several years to complete, are more difficult to judge. Consequently, for changes that take place over a long period of time, sound level shifts of 5 dBA or more may be "barely perceptible."
Table 4.8.1-1.--Subjective Response to Changes in Sound Level (.pdf)
Table 4.8.1-2.--Land Use Compatibility with Yearly Day-Night Average Sound Levels (in dB) (.pdf)
Except for the prohibition of nuisance noise, neither the State of Texas nor its local governments have established specific numerical environmental noise standards applicable to Pantex Plant. However, community annoyance surveys have provided a basis for establishing guidelines for sound levels compatible with various land uses. Table 4.8.12 shows land uses that are defined by the Federal Aviation Administration and the Federal Interagency Committee on Urban Noise as normally compatible with various noise exposures. This table is used to ensure compatible planning around airports and is appropriate for evaluating exposures from other noise sources. The guidelines define compatibility with noise exposure as a function of land use in terms of DNL. For all residential uses, compatibility is considered to exist with sound levels up to 65 dB without qualification and up to 75 dB for certain specific uses with suitable building features. For livestock farming and breeding, compatibility is considered to exist up to 75 dBA. These guidelines are advisory in nature and are not mandatory (14 CFR 150).
Also, the Environmental Protection Agency has determined that no significant effects on public health and welfare occur for the most sensitive portion of the population (within an adequate margin of safety) if the prevailing DNL is less that 55 dB (NAS 1977).
Major noise emission sources within Pantex Plant include various industrial facilities, equipment, and machines. Traffic is the primary source of noise at the site boundary and at residences near roads. Other sources of noise include aircraft, wind, insect activity, and agricultural activity.
4.8.1.1 Ambient Noise Levels
A survey of outdoor ambient sound levels at Pantex Plant, both onsite and offsite, was conducted September 816, 1994. During this time a total of 11 locations were selected as representative of onsite sound levels and the noise environment of offsite receptors. Figure 4.8.1.11 shows the measurement locations that are representative of those adjoining Pantex Plant and the location of points for which acoustic modeling was used to predict noise from blasts at firing sites. The figure also shows those onsite noise sources that have been identified as audible at offsite locations. These sources are the high explosive(s) (HE) firing sites and the target range used by Pantex Plants Security and Courier sections. The summer-autumn sound survey was augmented with an autumn-winter survey conducted December 13, 1994. At this time, four locations (J, K, L, and M) were added, and measurements were made at these and one of the previously monitored locations, location F.
Traffic is the primary source of noise at the site boundary and at residence near roads. As shown in Table 4.8.1.11, Leq levels ranged from 38 to 58 dBA. Onsite noise Leq levels generally ranged from 40 to 60 dBA. However, measurements which were C-weighted indicated noise levels at a distance of 366 meters (1,200 feet) from the target ranges of 70 to 103 dBC (Pantex 1996:11.2.1, 11.2.3). A summary of the noise measurements is presented in Table 4.8.1.11.
4.8.1.2 Occupational Noise
Representative occupational noise levels are summarized in Table 4.8.1.21. The noise levels are representative of exposure-monitoring data obtained in the hearing conservation program. In addition to industrial noise exposure, the data include noise exposure of Security and DOE Courier section personnel while maintaining weapons proficiency.
4.8.1.3 Noise from High Explosive Detonation
Pantex Plant detonates explosive charges in open air. These charges generally vary in weight from 2 to 21 kilograms (5 to 47 pounds). During 1994, Pantex Plant detonated 60 charges of HE (Pantex 1996:11.2.2). The maximum HE charge exploded was 24.9 kilograms (55 pounds). In October 1995, during an emergency preparedness training exercise, a charge greater than 24.9 kilograms (55 pounds) of HE was detonated. Since the plant does not typically detonate charges larger than 25 kilograms (55 pounds) of HE equivalent, that size charge was modeled for various wind speeds. Should a larger charge be exploded in the future, the plant would perform appropriate NEPA review for that charge.
Airblast noise resulting from the detonation of HE is impulsive in nature and generally lasts less than a second in duration. Although the duration of individual blasts is short, the rapid onset of such sounds could be a source of discomfort to many persons. In addition, the vibration of buildings and other structures induced by the noise impulse could be a source of increased annoyance. This vibration and the rapid onset produce "startle" effects.
The noise produced by airblast results from the generation of shock waves. Figure 4.8.1.31 depicts a typical blast impulse, which consists of an abrupt compression (characterized by an extremely short rise time) followed by a gradual pressure reduction to below ambient pressure, and finally a recovery to ambient. The overpressure (and therefore the noise level) is a function of the source strength (charge weight), meteorological conditions, and distance to observer. For explosions aboveground, propagation of the airblast is influenced by wind and temperature gradients, which can create focusing effects.
Table 4.8.1.1-1.--Summary of Noise Measurements at and in the Vicinity of Pantex Plant (.pdf)
Figure 4.8.1.3-1.--Typical Blast Impulses.
Table 4.8.1.2-1.--Representative Employee Noise Exposure at Pantex Plant (.pdf)
There is no record of measurements of noise levels or overpressures made in connection with Pantex Plant detonations. Therefore, an airblast prediction model called BLASTOBLASTO was used to estimate the overpressures resulting from Pantex Plant HE detonations (Reed 1995:1-17). A neutral lapse rate was assumed. Overpressures (dB) and their downwind distances from the source are presented for three wind speeds in Table 4.8.1.31. As shown in the table, the maximum size of Pantex Plant HE detonations could be audible out to distances of 5 to 10 kilometers (3 to 6 miles), depending on atmospheric conditions.
4.8.2 Impacts of Proposed Action
4.8.2.1 Impacts of Continued Operations
Operations are assumed to continue at any of the three potential annual activity levels for the approximately 10-year period examined in this EIS. The three activity levels are for operations on 2,000, 1,000, and 500 weapons per year.
Noise levels onsite and near the Pantex Plant boundary for operations on 2,000 weapons per year would be about the same as those which currently exist (see section 4.8.1.1). Noise sources would consist of vehicular traffic, industrial facilities, aircraft overflights, and railroad trains. Traffic is the primary source of noise at the site boundary and at residences near the Farm-to-Market (FM) roads adjacent to Pantex Plant boundary. Noise levels (Leq) range from 40 to 60 dBA. Target range noise at 366 meters (1,200 feet) ranged from 70 to 103 dBC. Aircraft overflights can produce maximum noise levels of 90 dBA (Pantex 1996:11.2.1 and 11.2.6).
A reduction to operations on 1,000 and 500 weapons per year would produce some decrease in noise levels because of reduced traffic, resulting from fewer employees commuting to and from work. Noise from HE detonations would continue for all three levels of weapon operations. On the other hand, the frequency of explosive tests would decrease as the level of weapons decreased.
Except for airblast noise, noise levels at the Pantex Plant boundary for all three levels of weapon operations would be below the 65 dBA guideline level (see section 4.8.1). Thus noise impacts from the usual noise sources at Pantex Plant would be negligible. Airblast noise resulting from detonation of HE would continue for the 2,000 weapons level at about the same frequency that is currently used at Pantex Plant. The reduction of weapons levels to the 1,000 and 500 unit levels would likely result in fewer HE detonations. Since current levels of HE detonations have not generated significant noise impacts at any of the residences near the Pantex Plant boundary, continued operations would, therefore, not produce significant noise impacts at these sensitive receptors.
Pit Storage ActivitiesThe principal noise source from pit storage activities would be the tractor-trailers used to haul the weapons or pits to Pantex Plant. The number of tractor-trailers would be a very small fraction of the total traffic generated by Pantex Plant (less then 0.2 percent). Overall noise level increases resulting from pit storage activities would not be detectable by the human ear (see Table 4.8.11). Therefore, noise impacts from pit storage activities would be negligible.
Environmental Restoration ActivitiesEnvironmental restoration activities will require various types of construction equipment to cleanup hazardous waste sites on Pantex Plant. Types of equipment would include bulldozers, backhoes, front-end loaders, drill rigs, and dump trucks. Noise levels in the immediate vicinity (15 meters [50 feet]) of the remediation site would range from 80 to 90 dBA.
These noise levels would be reduced to 45 to 55 dBA at 914 meters (3,000 feet) from the remediation area. This is the approximate distance from a remediation site to the nearest residence. These noise levels are about the same as the ambient noise levels existing at the residences near the Pantex Plant boundary. Thus, noise levels generated by restoration activities on Pantex Plant would not be noticeable at the sensitive receptors outside the plant boundary. Noise impacts from environmental restoration activities, therefore, would be negligible.
Waste Management ActivitiesSources of noise from waste management activities are trucks which haul waste offsite, a garbage truck, a document incinerator, and two compactors. About one truck per week is used to haul waste offsite. Onsite sources are at sufficient distance from the Pantex Plant boundary that noise originating from these sources would not be detectable at the boundary or at any of the sensitive receptors outside the boundary. Therefore, noise impacts from waste management activities would be negligible.
4.8.2.2 Impacts of New Facility Construction and Upgrades
Noise sources during the new facility construction and upgrade would include heavy-construction and increased traffic. Small increases in traffic would occur onsite and along offsite transportation routes used to bring construction material and workers to the site. Small increases in noise levels would occur at the residences located along FM Roads 2373 and 683. Noise levels would be below the 65 dBA level specified as acceptable in the Federal Interagency Committee or Urban Noise guidelines (see section 4.8.1). Due to the size of the site, noise emissions from construction and operation activities of the facilities would not be expected to cause annoyance to the public. Therefore, noise impacts associated with construction and operation of the new facilities would be negligible.
4.8.2.3 Summary of Impacts
Noise levels associated with the Proposed Action may be increased slightly during construction activities. Operational noise levels from operations on 2,000 weapons per year would be approximately the same as the noise levels which currently exist onsite and offsite. Airblast noise levels from HE detonations would also continue at current levels. The reduction to the 1,000 and 500 weapons per year levels would reduce noise levels a few decibels. Therefore, noise impacts associated with the Proposed Action would be negligible.
4.8.3 Impacts of No Action Alternative
Noise sources for the No Action Alternative would be similar to those of the Proposed Action. Three levels of activity, operations on 2,000, 1,000, and 500 weapons per year, are assumed for the No Action Alternative. The major difference between this alternative and the Proposed Action is that weapons disassembly operations would cease when 12,000 pits have been placed in storage at Pantex Plant. Construction of new facilities would not take place under the No Action Alternative. Therefore, construction noise levels would be less than those described for the Proposed Action (see section 4.8.2). bk0high explosive(s) (HE) HE detonations would continue at about the same level as would occur under the Proposed Action.
Noise impacts for this alternative would therefore be approximately the same as the Proposed Action; i.e., they would be negligible.
Pit Storage ActivityImpacts of pit storage activities under this alternative would be the same as the Proposed Action until the 12,000 pits are stored. After this storage level is achieved, transportation of pits to other facilities would occur. Overall, the noise levels resulting from these activities would be about the same as the Proposed Action. Noise impacts for pit storage activities under this alternative would, therefore, be negligible.
Environmental Restoration ActivitiesNoise sources and resulting noise levels associated with environmental restoration under this alternative would be the same as those described under the Proposed Action. Noise impacts, therefore, would be negligible.
Waste Management ActivitiesNoise sources and resulting noise levels related to waste management activities would be the same as those under the Proposed Action. Noise impacts would be negligible.
4.8.4 Impacts of Pit Storage Relocation Alternative
4.8.4.1 Impacts of Relocating 20,000 Pits
The principal source of noise would be from the tractor-trailer units used to haul the pitpits to another facility. Over a 10-year period, this would involve no more than one or two shipments per week. The increase in noise levels over general plant activity noise levels would not be detectable. Thus, noise impacts under this alternative would be negligible.
4.8.4.2 Impacts of Relocating 8,000 Pits
Noise levels related to this activity would be less than those related to relocating 20,000 pits. Noise impacts, therefore, would be negligible.
4.8.5 Cumulative Impacts
The cumulative impacts presented here include impacts of the continued operations at Pantex Plant combined with impacts associated with activities described in the WM PEIS, SSM PEIS, and S&D PEIS. Since the Pantex Plant EIS Proposed Action and the SSM PEIS No Action Alternative represent a continuum of operations, the impacts associated with any new mission or facility that could be implemented at Pantex Plant are discussed in the context of that continuum. The impacts from the WM PEIS program are combined with those of the Pantex Plant EIS Proposed Action. The impacts from the S&D PEIS are combined with those of the SSM PEIS No Action Alternative. A detailed discussion of this methodology is presented in section 4.2.
4.8.5.1 Impacts of Alternatives in the Waste Management Programmatic Environmental Impact Statement
Should the WM PEIS result in a decision to site waste management facilities at Pantex Plant, future NEPA documentation would be prepared for the specific project and specific location proposed in order to assess noise impacts on workers, offsite populations, and other sensitive receptors.
Noise sources during construction of the waste management facilities would include heavy construction equipment and increased traffic. Increased traffic would occur onsite and along major offsite transportation routes used to bring construction material and workers to the site. Most nontraffic noise sources associated with operation of any waste management facilities would be located at sufficient distance from offsite areas that the contribution to offsite noise levels would continue to be small. Due to the size of Pantex Plant Site, noise levels from construction and operation activities would not be expected to cause annoyance to the public (DOE 1995k). Therefore, the cumulative noise impacts of the Proposed Action and the construction and operation of the waste management facilities would be minor and not significant.
4.8.5.2 Impacts of Alternatives in the Stockpile Stewardship and Management Programmatic Environmental Impact Statement
The SSM PEIS includes three alternatives that apply to Pantex Plant: No Action, Downsize Existing Capability, and Relocate Capability. Under the No Action Alternative, no downsizing or modification of facilities would occur. Due to the reduced workload expected in the future, noise impacts from operations are expected to be less than current impacts. Under the downsizing alternative, facilities would be consolidated. The noise impacts would be equivalent to the No Action Alternative. Under the relocation alternative, noise from assembly and disassembly operations and HE fabrication would cease.
4.8.5.3 Impacts of Alternatives in the Storage and Disposition of Weapons-Usable Fissile Materials Programmatic Environmental Impact Statement
The S&D PEIS is considering Pantex Plant for long-term 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. The storage alternatives include upgrading the existing plutonium storage facilities, consolidation of plutonium from other sites, and collocation of plutonium and HEU storage. The collocation alternative is used for analysis purposes in this EIS as the bounding storage alternative.
Under the S&D PEIS Collocation Alternative, construction of new storage facilities would be required in order to store plutonium and HEU at Pantex Plant. Nontraffic operational noise sources associated with the consolidation of plutonium and collocation of plutonium and highly enriched uranium alternatives include additional equipment and machines. These noise sources would be located at sufficient distance from offsite areas that the contribution to offsite noise levels would be small. Due to the size of the site, noise emissions from construction equipment and operations activities would not be expected to cause annoyance to the public.
For the disposition alternatives in the S&D PEIS, the emphasis at this stage in the NEPA decision process is on the strategy and technology mix rather than the actual site. The evolutionary Light Water Reactor is used for analysis purposes in this EIS as the bounding disposition alternative. Implementation of this disposition alternative would require the construction and operation of a pit disassembly and conversion facility, plutonium conversion facility, mixed oxide fuel fabrication facility, and a light water reactor. The bounding alternative also assumes that all of the facilities previously mentioned would be collocated at the same site (potentially Pantex Plant).
Nontraffic operational noise sources associated with the Disposition Alternative includes additional equipment and machines. These noise sources would be located at sufficient distance from offsite areas that the contribution to offsite noise levels would be small. Due to the size of the site, noise emissions from construction equipment and operations activities would not be expected to cause annoyance to the public (DOE 1996a:chapter 4). However, should Pantex Plant be selected as the site for such a facility, further NEPA review would be performed to assess the noise impacts on workers, offsite populations, and other sensitive receptors.
4.8.6 Potential Mitigation Measures
DOE currently uses standard silencing packages on construction equipment and provides workers in noisy environments with appropriate hearing protection devices meeting Occupational Safety and Health Administration (OSHA)Occupational Health and Safety Administration standards. As required, noise levels are measured in worker areas, and a hearing protection program has been implemented. This program would continue in the future.
While the amount of offsite noise from explosives testing at the plant is not significant and no mitigation measures are required, DOE could chose to implement such measures as limiting the hours of such testing or setting prohibitions on testing during unfavorable atmospheric conditions to further reduce the noise levels.
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