DEIS Thirty Meter Telescope Project UH @ Hilo Vol 1 (TPD0905015)

3.14.1           Environmental Setting

This section discusses the air quality, climatic, and sky lighting conditions in the region and specific Project areas.

Maunakea Summit Region

Air Quality

Air quality and climate are very important siting considerations for observatories, as unique visibility conditions are required for astronomical observations. Although many studies have been performed to evaluate astronomical seeing conditions, traditional air quality monitoring has not been actively undertaken at the summit of Maunakea. Traditional air quality monitoring consists of monitoring for ozone, carbon monoxide, particulate matter – including respirable particular matter, and particular matter less than 2.5 microns in diameter, nitrogen dioxide, sulfur dioxide, lead, and visibility-reducing particles.

Air quality monitoring has been performed at the Mauna Loa Observatory at an elevation of approximately 11, 140 feet since its construction in 1956. This monitoring station provides data most representative of the conditions at Maunakea. The data gathered at this station indicate that the air quality at the Mauna Loa Observatory is excellent and in attainment status with State and National Ambient Air Quality Standards (NAAQS). Given the similarities between the two locations (Maunakea and Maunaloa), it has been inferred that the overall air quality at Maunakea is excellent as well.

The Maunakea summit area rises well above the atmospheric temperature inversions that occur around 7,000 feet. Particulates and aerosols like vog (volcanic gas), smog, dust, smoke, salt particles, and water vapors generated below the inversion level are “capped” by the temperature inversion, so they do not rise above the inversion level and do not cause any interference at the summit. Locally generated contributors to air pollution above the inversion level include vehicle exhaust, chemical fumes from construction and maintenance activities, and fugitive dust from road grading and construction or other activities conducted on unpaved surfaces. Rapid dispersion of pollutants is aided by strong winds.

Climate

There are two seasons in Hawai‘i, winter (October–April) and summer (May-September), with the trade winds blowing approximately 80 percent of the time in the summer and 50 percent of the time in the winter. Winter temperatures on Maunakea range from 25 to 40 degrees Fahrenheit, but wind chill can bring the temperature to below zero; summertime temperatures recorded at the summit area range from 40 to 60 degrees.

In the summit region, annual precipitation ranges from approximately 20 inches at the Very Long Baseline Array (VLBA) at an altitude of 12,600 feet to approximately 15.5 inches (including snowfall) at the Subaru Observatory at an altitude of 13,575 feet. Storms, including wintertime cold-fronts, upper-level and surface low-pressure systems, tropical depressions, and hurricanes provide the majority of annual precipitation over a very short period of time.

Although no data on average snowfall is available, it is known that from November through March varying amounts of snow and ice regularly fall near the summit.

Wind velocities usually range from 10 to 30 miles per hour in the summit region. During severe winter storms though, winds can exceed 100 miles per hour on exposed summit areas, such as the tops of cinder cones.

Some of the Maunakea summit’s other unique characteristics include its minimal cloud cover, with about 325 days per year being cloud free, and the low water vapor level, which means the atmosphere is more transparent for infrared observations. The dry and breezy conditions facilitate high rates of evaporation at the summit and maintain the cool, dry atmosphere.

Sky Lighting

Another characteristic that makes Maunakea one of the best sites in the world for astronomical observations is the very dark sky. This results from the summit’s remoteness from urban development, as well as the County of Hawai‘i’s island-wide lighting ordinance requirements. Three main types of high-intensity outdoor lighting are used in cities: low pressure sodium (LPS), high pressure sodium (HPS), and mercury vapor lamps. Of these, LPS is the choice of astronomers because light from LPS bulbs is concentrated in a very narrow part of the spectrum, leaving all other wavelengths uncontaminated. Therefore, light and radiation in other parts of the spectrum from stars, galaxies, and planets can be viewed and be valuable for astronomers. HPS or mercury vapor lamps contaminate much of or the entire spectrum that astronomers study, and areas that are brightly illuminated by these kinds of lights are unusable for astronomical measurements. The absence of air pollution and the absence of large, brightly-lit cities on the Island of Hawai‘i give astronomers some of the deepest views into the universe that can be achieved at ground based observatories.

Hale Pōhaku

Air Quality

Air quality at the Hale Pōhaku facilities is similar to that at the summit because it is also located above the temperature inversion level.

Climate

Average temperatures at Hale Pōhaku, at 9,200 feet, range between 30 and 70 degrees Fahrenheit throughout the year. Average wind speeds at 8,530 feet at Pu‘u La‘au, near Hale Pōhaku, range between 2.7 to 3.6 miles per hour. Annual precipitation ranges from 12 to 20 inches, with most rain occurring between November and March. Fog is common, while snow is rare.

Headquarters

Currently, no routine ambient air monitoring is conducted by HDOH in the Hilo area. Historical monitoring during the 1970s and 1980s indicated very low pollutant levels in Hilo. Recent increase in volcanic activity has led to higher than average levels of vog, although the western side of the island is affected more than Hilo.

Hilo is located on the eastern, or windward, side of the island and is usually subjected to northeasterly trade winds during the day. These wind speeds predominantly range from 4 to 12 miles per hour.  Daytime temperatures range from the upper 70s to low 80s in degrees Fahrenheit, while temperatures at night range from the low 60s to the upper 70s. The annual rainfall in Hilo averages about 141 inches. Although the wet season usually occurs from October through April, rain falls approximately 280 days of the year.

Hilo, and the rest of the island, uses only LPS bulbs for outdoor lighting.

Satellite Office

The mean annual rainfall in the Waimea area is 31 inches per year, and the rainfall distribution is highly variable; the drier, more leeward, portions of Waimea receive 20 inches per year, while the wetter, more windward, portions receive approximately 75 inches per year. The average wind speed is 20 miles per hour from the east-northeast trade wind direction, though the wind speed exceeds 20 miles per hour more than 50 percent of the time. The average monthly temperature in Waimea varies from 61 to 67 degrees Fahrenheit.

Waimea, and the rest of the island, uses only LPS bulbs for outdoor lighting.

3.14.2           Thresholds Used to Determine Level of Impact

In accordance with the Chapter 343 significance criteria, the Project would result in a significant impact if it would result in a detrimental effect on air quality leading to a substantial degradation in environmental quality. Thus, the Project impact would be considered to be significant if it would result in emissions of air pollutants that could substantially impair the existing air quality through generation of substantial pollutant concentrations and/or lead to the area becoming a non-attainment area for State and NAAQS.

3.14.3           Potential Environmental Impact

Air pollutants emissions associated with the Project would include dust (or particulate matter) and exhaust fumes from vehicular travel, plus emissions related to maintenance activities. Dust would be the primary air quality concern along the unpaved portion of the Maunakea Access Road and the Access Way. The Observatory staff of approximately 44 day-time personnel and six night-time personnel would travel to the TMT Observatory daily. Deliveries and pickups, including trips made for equipment, supplies, water, and waste, would generate additional trips to and from the TMT Observatory.

Potential air quality and climate impacts resulting from fugitive dust include decreased surface albedo⁵¹, and associated increased rate of snow melt at higher elevations; disruptions to photosynthesis by vascular plants due to dust fall out; potential impacts on Wēkiu bug habitat; reduced clarity of view for both the human eye and for astronomical technologies; and safety concerns. Potential air quality and climate impacts resulting from vehicle exhaust emissions include reduced health within the lichen and moss communities, and reduced clarity of view for both the human eye and for astronomical technologies.

The potential dust-related impacts to biological resources, such as plants, lichen, moss, and Wēkiu bugs are discussed in Section 3.4.3. The potential for increased snow melt due to dust would only be an issue along the unpaved portion of the Access Way; and this potential for slightly quicker melting of snow along the Access Way due to dust is not considered significant because the longevity of the snow or rate of melting does not change the fate of the melt water (groundwater recharge) and no species rely on the presence of the snow. Also, the potential increased melt rate may be offset by the snow along the Access Way being thicker once the road is plowed clear.

The small number of daily vehicular trips beyond Hale Pōhaku has no potential to generate air pollutant emissions that could substantially impair the existing air quality or affect the health of lichen and moss communities. The vehicles would be in compliance with industry emission standards and regularly maintained. In addition, the potential impacts to air quality from pollutants other than dust are likely to be temporary because the nearly constant winds at the summit would quickly disperse them.

The Headquarters in Hilo is anticipated to have a staff of approximately 60 employees; the Satellite Office in Waimea is anticipated to have a staff of approximately 30 employees. The vehicular traffic associated with employee travel and typical deliveries and pickups at these facilities would represent slight increases over the current traffic conditions in the areas. Those trips would generate minor amounts of exhaust emissions with no potential to impair the existing air quality because those vehicles would be in compliance with applicable emissions standards.

The ongoing standard maintenance of the Project’s facilities would not involve any activities that could generate substantial air pollutant emissions. In the rare instances that the emergency generator may be required, minor diesel exhaust emissions would occur. The Project would comply with existing requirements to limit the emissions from the generator, and the generator would meet Federal emissions standards, while the diesel fuel used would meet Federal requirements regarding sulfur content and cetane index. Therefore, occasional use of the emergency generator has no potential to result in air pollutant concentrations at the summit that could impair the existing air quality.

Overall, the impact of the Project on air quality and the climate would be less than significant. The excellent air quality due to the island’s climatic conditions, including winds that rapidly disperse pollutants and prevent their concentration, would not be degraded. The Project does not include any features or activities that could substantially change either precipitation, temperature, wind velocities, inversion levels, cloud cover, water vapor or any other climate factors at Maunakea or the Island of Hawai‘i.

The Project would comply with lighting standards for outdoor lighting. This would include minimizing the use of exterior lighting, and using LPS lighting with suitable shielding for all necessary outdoor lighting. At the TMT Observatory, there would be no outdoor lighting because it would interfere with observatory operations. The TMT Observatory’s AO system would utilize laser guide stars. The multiple overlapping laser beams could be faintly visible to the naked eye as a single beam on moonless nights for a distance of up to 9 miles from the observatory. The area where the laser may be visible consists primarily of ranchlands and forest reserve which are not populated. The Federal Aviation Administration requires that the lasers be shuttered when aircraft are present in the area of the sky where the laser beams are pointed.

Aircraft would be detected automatically using multiple camera systems, supplemented initially by human spotters if necessary. Therefore, the Project would not illuminate the sky or significantly impact nighttime conditions on the island.

3.14.4           Mitigation Measures

TMT would prepare and implement a Ride-Sharing Program, as outlined in Section 3.11.4. The program would require all personnel working at the TMT Observatory to ride-share in observatory vehicles beyond Hale Pōhaku, or a lower elevation location, to the summit area. The observatory vehicles would be selected based on balancing the needs for fuel efficiency, low emissions, and safety for transportation to the summit.  Approximately 10 vehicles would be used for day-time trips and two for night-time trips. This required ride sharing would reduce the total number of Project trips beyond Hale Pōhaku to the summit area to approximately 14 trips per day (12 staff trips and 2 other trips, such as deliveries), and would further reduce the potential impact of the Project on air quality.

There is a possibility the Project would employ a soil-binding stabilizer, such as DuraSoil, to control dust on the unpaved section of the Access Way between the SMA and the TMT Observatory. This would reduce dust generated along the short 3,000 foot (0.6 mile) section of unpaved Access Way.  This is primarily being considered to mitigate possible impacts to biologic resources due to dust in the summit area, but would also benefit air quality. Soil- binding stabilizers would be used sparingly, and would never be applied to habitat adjacent to the road or parking areas. Prior to the use of a soil-binding stabilizer the Project would coordinate with OMKM and Kahu Kū Mauna and only proceed with their concurrence.

In addition, the Project’s Ride-Sharing Program would encourage and support the establishment of ride sharing by its Headquarters and Satellite Office staff. This would further reduce the potential impacts associated with the Project. TMT may also consider flexible hours for staff at these facilities, as necessary, to further reduce the potential impact.

The TMT Observatory would also coordinate the use of its AO laser guide stars with the other observatories on Maunakea using the existing Laser Traffic Control software system to minimize the interference between the various guide star systems in use, as well as their impact on other astronomical observations.

3.14.5           Level of Impact after Mitigation

The Project would not have a significant impact on air quality or climate, even without mitigation. Compliance with existing requirements would ensure that the air quality would remain in compliance with the State and NAAQS and therefore no significant impacts are expected. The outlined mitigation measures would further reduce the Project’s minor impact on air quality in the summit area.

3.14.6           References

Arvidson, R. E. 2002. Draft environmental assessment for the Outrigger Telescopes Project published by NASA in December 2000; Response to comments concerning the hydrology of Mauna Kea. Outrigger. St. Louis, MO, McDonnell Center for the Space Sciences, Dept. of Earth and Planetary Sciences, Washington University.

da Silva, S.C. 2006. Climatological analysis of meteorological observations at the summit of Mauna Kea. Physics Department, University of Lisbon; 77p.

Giambelluca, T. W. and M. Sanderson. 1993. The Water Balance and Climate Classification. Prevailing Trade Winds, Weather and Climate in Hawai’i. M. Sanderson. Honolulu, University of Hawai‘i Press.

Jurvik, S. P. and J.O. Jurvik, Eds. 1998. Atlas of Hawai‘i. Honolulu, University of Hawai‘i Press

Laws, E. A. and A. H. Woodcock. 1981. Hypereutrophication of an Hawaiian alpine lake. Pacific Science 35(3): 257-261.

Miyashita, A., N. Takato, et al. 2004. Statistics of weather data, environmental data and the seeing of the Subaru Telescope. Ground-based Telescopes. J. M. Oschmann, Proc. of SPIE. 5489: 207-217.

NASA. 2005. Final environmental impact statement for the Outrigger Telescopes Project: Mauna Kea Science Reserve, Island of Hawai‘i. National Aeronautics and Space Administration, Universie Division, Science Mission Directorate Washington, D.C.

Nullet, D., J. O. Juvik, et al. 1995. A Hawaiian mountain climate cross-section. Climate Research 5: 131-137.