NOISE
STANDARD OF REVIEW
According to the CBJ Mining Ordinance (49.65.135(a)(4)), the CBJ shall require that:
The CBJ Land Use Code 49.15.330(g)(11) states that, in granting a conditional use permit, the CBJ may include:
Policy 3.15 of the CBJ Comprehensive Plan (1996) states:
BACKGROUND
The State of Alaska has no regulations limiting environmental noise impacts. The U.S. Mine Safety and Health Administration (MSHA) regulates the noise to which mine workers may be exposed. The U.S. Forest Service has guidelines for noise increases for recreational areas based on the recreational classification of the affected area, and specified certain noise limits to be placed on the ore grinding facilities at the Kensington mine.
The Final SEIS (1997) does not provide a discussion of the issue of project-related noise beyond that originally described in the Final EIS (1992). The noise associated with the project can be divided into two categories: continuous and intermittent. Continuous noises would result from functions such as ore milling and electrical power generation. Intermittent noises would come from activities such as supply barge unloading; vessel, air, and surface traffic; blasting in borrow pits; and rock and tailings transport, dumping, and spreading during construction of the dry tailings facility (DTF). Additionally, some blasting at the shore-side fuel storage facility and other "short term" noise would occur during the construction and reclamation phases. See Pages 4-117 through 4-124 of the Final EIS (1992) for additional information and discussion
Predictions about the level and duration of sounds emanating from various sources at the site were obtained through computerized noise propagation modeling by the firm of Hart Crowser, for Coeur Alaska, Inc., in February 1997(1). The modeling used several receptor sites in and around the project area, and accounted for effects of terrain, vegetation, background noise, weather, and noise source and location. For the modeling, source sound levels were derived from manufacturers' noise data or from literature values. Table 3-1 from the Hart Crowser report, which summarizes the noise sources, contributing activities, mitigation measures, and modeled noise emissions, is attached.
The loudest noise sources would occur intermittently. Some would only occur during certain phases of development, such as blasting during construction of the fuel storage area. Other intermittent noises, such as DTF construction and transportation access will occur throughout the life of the project. Intermittent noises, such as blasting, because of characteristics of the source as well as the noise, are not as conducive to abatement.
The applicant's Amended Plan of Operations (August 1997) does not address noise in great detail. The original project proposal stated that natural noise barriers such as trees and vegetation will be left standing as much as possible in order to take advantage of the sound absorption features that already exist on-site. Vegetative barriers would serve both as a sound barrier and as a partial visual screen of facilities and activities in the project area from offshore views.
The coming and going of vessels and aircraft to the site will generate noises beyond what is directly attributable to site sources. A substantial part of the transport noise would come from the daily 2-4 helicopter flights carrying employees to and from the mine site at shift changes during operations, and with more frequent flights during mine construction. Following the applicant's proposed travel route, a helicopter would leave the Juneau Airport and proceed northwest following the Montana Creek and Windfall Creek drainages. From there the proposed flight path is toward the mouth of Cowee Creek, across Berners Bay, and along the coastline that parallels Lynn Canal to the mine site (see figure) According to the applicant's Amended Plan of Operations, the flight path is positioned over land as much as possible for safety considerations. During times of poor weather and low visibility, the applicant states that variations with the normal flight path could occur. The Final EIS (1992) indicates that during cloudy weather with low ceilings, the helicopters would travel along the coast at an altitude determined by safety. The applicant's Amended Plan of Operations states that the minimum flight elevation for the helicopter would be maintained at 300 feet. When weather allows, the helicopter would travel at altitudes of up to 2,000 feet, and the highest practicable elevation would be maintained over residential areas.
Noise level measurements are expressed in units called "decibels", and are related to human perception of loudness on a scale called dBA. Another measurement, Ldn (day-night sound level), is the average sound level for a 24-hour period. Ldn is usually expressed in dBA.
The U.S. Environmental Protection Agency recommends the use of an "A-weighted" scale for noise measurement when analyzing community noise impact levels. For example, an average home produces a noise level of about 45 dBA. A quiet whisper produces about 30 dBA, while a chain saw can produce over 110 dBA. An office with two typewriters going produces about 63 dBA. A printing plant produces a 90-dBA sound level.
ANALYSIS
Compared with the action recommended in the 1992 Record of Decision (ROD) and the Final EIS (1992), the applicant's current proposal and the preferred alternative in the Final SEIS (1997) include some changes that would affect expected noise from the project. These include:
According to the 1997 Hart Crowser study which incorporates these changes, the expected noise from the applicant's project would not exceed the CBJ standard of 55 dB(A) at the project site boundary, except at the west boundary at Comet Beach. At the west boundary the 55 dB(A) noise level is reached about 900 feet off shore for continuous activities, and extends to about 1,400 feet offshore for intermittent activities. According to the study, the noise level would be about 48 dB(A) at a distance of approximately one mile offshore, where cruise ship or ferry traffic would be expected.
The use of a pipeline to transport tailings slurry would generate less noise than trucks hauling tailings. Reduced noise in transporting tailings, however, may be a tradeoff to other impacts of a tailings pipeline (i.e.,the potential for a sizable tailings spill from pipeline rupture).
The following are potential impacts of noise from the Kensington Gold Project.
Impacts to Residential Areas. The proposed flight path takes the helicopters over very little residentially developed land. It bypasses the main residential areas of the Mendenhall Valley and along Glacier Highway north of Auke Bay. Given the flight path, elevation, and the small number of helicopter flights each day, noise impacts on residential areas are expected to be minimal.
Impacts to Wildlife. Noise and activity associated with the project may disturb wildlife in the project area and cause changes in wildlife occurrence and distribution. Noise disturbances may include helicopter use, milling, blasting, hauling, construction, and other activity associated with the mine and camp.
The possible disturbance of mountain goats due to helicopter noise received considerable attention during project evaluation. Helicopter flights to the site will generate noise that could disturb and displace goats. Hart Crowser (1997) states that mountain goats in areas of occupied habitat could be exposed to noise levels of 60 dB(A) or less for a very short duration. Furthermore, the Hart Crowser study also states that "...[i]t is not expected that the small amount of additional noise created by the Kensington flights would have any measurable effects on mountain goat populations in proximity to the flight corridor."
To address the concern regarding helicopter noise, the Amended Plan of Operations (August 1997) states that employees will be trucked from the heliport to the housing camp. The Final EIS (1992) indicates that noise from mine construction, operation, and helicopter use would be expected to displace mountain goats from portions of their range near the project area. Currently, approximately 100 goats inhabit the west side of Lions Head Mountain (Robus, 1997). The rough draft of the Effects of Kensington Mine Development on Black Bears and Mountain Goats (ADFG, 1996), a wildlife baseline studies and monitoring plan prepared by Alaska Department of Fish and Game, indicates that the level of monitoring is not likely to produce enough information to determine cause and effect relationships between mountain goat movement patterns and mineral development. Coeur and ADFG, in consultation with the U.S. Forest Service and CBJ, has developed a revised monitoring approach to annually survey the mountain goats in the area to examine the long-term potential for population displacement. See the staff report on Wildlife for more information.
Black bear response to noise and disturbance from mining activities has not been monitored in Southeast Alaska. The potential for displacement and possible displacement distances are not known. Monitoring at the Kensington site, conducted since 1990, indicates that bears have continued to use the area around the camp and mine portal during exploration activities. Results from the telemetry work on collared bears (see Effects of Kensington Mine Development on Black Bears and Mountain Goats) indicates that there is a high density of black bears and that denning occurs within the project area. As discussed in the staff report on Wildlife, Coeur is focusing attention on food handling, garbage disposal, and employee training to minimize bear attraction and bear-human interactions.
Bald eagle nest trees occur along the coast line near the project area. While no nest trees will be lost due to project construction and operation, eagles may be disturbed by helicopter and other project noise. Coeur will follow the requirements of the interagency agreement between the U.S. Forest Service and U.S. Fish and Wildlife Service to prohibit construction near active eagle nest trees and to minimize noise disturbance to the eagles.
A small population of Stellar sea lions, listed as endangered, haul out and feed in the area of Point Sherman. Low-level helicopter flights or barges in the vicinity could cause abandonment of these sites by sea lions if no effort is made to avoid disturbance. The maintenance of a buffer between project activity (particularly barge traffic) and haulouts is necessary to avoid harassment, which is prohibited under the federal Marine Mammal Protection Act. The staff report on Transportation also addresses this issue.
Humpback whales, listed as endangered, are seasonally present in marine waters adjacent to the project site. Although the exact number of whales in Lynn Canal is unavailable, they are known to occur in the summer to fall feeding season. Humpback whales have been observed feeding off Point Sherman from April through June (Nanney, 1990). Important feeding areas include Glacier Bay, adjacent portions of Icy Strait, Frederick Sound and Stephens Passage. Each year concentrations of feeding whales are found in different areas, and their distribution in Alaskan waters is variable. Adverse impacts could come from displacement due to traffic or noise from vessel traffic. Displacement conflicts are at a minimum due to the consistent and relatively slow speeds of barge traffic, and to the large geographical area involved with a small whale population to absorb.
Largely to protect wildlife, the U.S. Forest Service considered, then abandoned, the idea of moving the applicant's preferred location of the ore grinding facilities and power generating plants. The U.S. Forest Service Record of Decision issued with the Final EIS (1992) stated that approval of the original location of these facilities is ". . . contingent upon design and monitoring verification by the proponent that structures housing these facilities can be designed to reduce noise produced in the structures to a level no higher than 79 dBA at a distance of 50 feet from the structures."
Impacts to Recreation. Sounds from actual mine site-based activities would be apparent to people who are recreating in the immediate area of the mine site. However, the area receives relatively little recreational use. In contrast, Berners Bay, to the south, hosts a variety of recreational users, primarily in the summer months. The noise modeling conducted by Hart Crowser (1997) and earlier for the Final EIS indicates that site-generated noises would not be audible in Berners Bay because of noise attenuating features such as topography and vegetation. Noise from some sources, such as vehicle backup alarms, have pure-tone characteristics that, even when below the background sound levels, make such noise objectionable.
The primary impact to recreation in the Berners Bay area will be noise from the proposed employee helicopter transport. However, this noise will be intermittent and located near the mouth of the bay along the proposed helicopter flight path, and will avoid most of the inner shoreline popular for kayaking and camping. As such, it is not believed to present a significant overall impact to recreational pursuits in the bay.
The proposed flight path also avoids much of the coastline where the public recreates at popular areas such as Auke Rec, Eagle Beach, the Breadline, Shrine of St. Terese, Eagle Beach, Sunshine Cove, and the Blue Mussel cabin at Point Bridget State Park. Echo Cove Ranch Camp and the recreation area at Echo Cove will experience helicopter overflights, but the noise impacts are considered minor because of the infrequent nature of the flights.
The general Lynn Canal flight route is already heavily used by other small aircraft, with perhaps as many as 200 flights per day possible during the summer months. This traffic is not regulated in terms of numbers by any agency. The level of air traffic has increased in recent years, and could continue to increase, unchecked, except for safety concerns. The Final EIS (1992) estimates that the flights proposed by the Kensington mine represent only about a 4 percent increase in the number of flights per month. Using the applicant's proposal of up to four flights per day, 30 days per month in 1997 and up to 200 flights per day, this represents something on the order of a 2 percent increase in small aircraft traffic during the summer months in the Berners Bay/lower Lynn Canal area. The Final EIS (1992) states that the additional air traffic generated by the mine is not expected to significantly increase noise levels in the vicinity because the existing amount of aircraft overflights is "...much greater than the incremental increases that would be contributed..." by mine transportation.
Helicopter traffic and its impact on other recreationists was addressed by the U.S. Forest Service in its helicopter tour landing study in 1987. That study recognized that helicopter traffic has an impact on other types of recreation. The Decision Notice, approving the management guidelines for the helicopter tours, stated that "...[t]he Forest Service will mitigate impacts to ground-based recreation uses in the Mendenhall Zone by enhancing trails in the northern portion of the Front Country (a geographic area extending from Auke Bay up the coast to the land at the northeast tip of Berners Bay), and the Herbert and Eagle Glacier zones."
The flight path proposed for the Kensington travels directly over each of these areas. Helicopter noise could potentially impact the recreational experience at Spaulding Meadows and Auke Nu hiking trails, the John Muir USFS recreational cabin, Montana Creek trail, Windfall Lake trail, Herbert River trail, Eagle River trail and Eagle Glacier USFS cabin, Bessie Creek trail, and Point Bridget State Park. However, the Kensington FEIS (1992) and Hart Crowser study (1997) reported a noise level of 72 dBA (i.e., the noise level of a vacuum cleaner) directly under the flight path of a helicopter flying 2,000 above the ground. The intermittent nature of the helicopter flights and the projected noise level of a mine employee helicopter support the view that impacts are anticipated to be modest.
The Forest Service further addressed this issue in a Final EIS for Helicopter Glacier Tours (1995). That FEIS specifically notes that the noise caused by the additional aircraft flights associated with the Kensington Gold Project "would not have a significant effect on wildlife, recreationists, or residents because any incremental increase would be small compared to the existing traffic volumes." Helicopter traffic under the revised project proposal, although including an additional 4 to 8 trips per week (with weekend flights) compared to the traffic expected in the previous proposal, would still be a small increase compared to existing traffic volumes.
Federal Aviation Administration Control of Air Traffic
Municipal regulation of aircraft noise, at least in the vicinity (i.e., within three nautical miles) of an airport, is generally limited because the Federal Aviation Administration has primary control over air traffic (Kolvig, 1997). As a general rule, the FAA directs helicopters where to fly only when there are other aircraft in the area or inclement weather. At other times, pilots may report their location and fly their helicopters over in less populated areas or at higher elevations to reduce noise impacts. In the interest of safety, helicopter traffic may be directed by the FAA to follow a path that results in higher noise levels on the ground. However, as cited by the U.S. Forest Service (Helicopter Glacier Tours Final EIS, 1995), the FAA recommends that aircraft fly at an altitude of 2000 feet over noise-sensitive areas.(2)
Recently, a Final Air Route Agreement for Airspace Users, Juneau, Alaska and Vicinity (May 29, 1997) was released by the FAA, which coordinated this effort undertaken by local air carriers and operators. The voluntary agreement identifies safe operating practices (i.e., preferred routes, specific altitudes for specified directions of flight in traffic conflict areas, radio frequencies, and reporting locations) in the area surrounding Juneau. The agreement, designed to be valid for a calendar year (and presumedly reviewed and renewed annually), specifies general procedures and specific procedures for four geographic areas (Juneau Airport, Juneau Icefield/Glaciers, Gastineau Channel/Taku Inlet, and Lynn Canal/Glacier Bay). The agreement does not restrict an aircraft operator from using other routes in uncontrolled airspace, but signatories agree to adhere to the procedures unless safety, weather, or traffic conflicts dictate otherwise.
The agreement specifies the following procedures that would be applicable to helicopters transporting Kensington mine employees.
B. Helicopters crossing a ridgeline may cross at 300 feet AGL.
C. Enter drainages (upstream direction), flying at 1000 foot levels (1000', 2000' ... MSL).
D. Exit drainages (downstream direction), flying at 500 foot levels (500', 1500'... MSL).
E. Normal traffic will fly on the right side of rivers, valleys, mountain passes, shorelines, or waterways, except as noted in specific area or when confronted with weather, traffic or other conflicts.
3. Specific Procedures for Lynn Canal & Glacier Bay:
B. Southbound traffic will use 1000 foot levels (1000', 2000' MSL).
The flight elevations and routes specified in the air operators' agreement do not appear to conflict with those proposed by the applicant for helicopters servicing the Kensington mine project. This agreement provides a more formal framework to informal efforts among the air operators over the past three years (Gordon, 1997). It is hoped that these procedures, developed locally, would be incorporated into potential FAA specific aviation regulations for tourism-related air traffic in the Juneau area which could be promulgated in the next couple years.
STAFF FINDINGS
(CBJ 49.15.330(e)(1)(B))
Yes.
2. Will noise from the proposed development endanger the public health or safety? (CBJ 49.15.330 (f)(1))
No. Evidence suggests that neither public health nor safety would be endangered by noise impacts of the project. Because of its remote location, noise from operations at the mine site would not affect human health or safety. Helicopter noise will be infrequent and generally located away from shoreline recreation users and residences.
3. What will be the effect of noise from the proposed project on the value of property in the neighboring area? Will project noise be out of harmony with property in the neighboring area? (CBJ 49.15.330 (f)(2))
No evidence suggests that noise impacts of the project will decrease the value of the property in the neighboring area. In the short term, the noise would be out of harmony with the surrounding area, as the mine is an industrial use in a semi-primitive area. However, following mine closure and reclamation, the original noise character of the area would be restored.
4. Will the proposed mine project be in general conformity with the comprehensive plan, thoroughfare plan, and other officially adopted plans as they may apply to noise? (CBJ 49.15.330(f)(3))
Yes. The project, as proposed and with the conditions recommended below, conforms with Policy 3.15 of the CBJ Comprehensive Plan, which addresses potential effects of noise. Mitigation includes a helicopter flight path which avoids most residential areas, flying at an elevation of at least 2,000 feet unless safety, weather, emergencies, or the FAA requires otherwise, and flights between 6 AM and 10 PM except during emergencies. Mine equipment will also use ambient-sensitive backup alarms to minimize unnecessary noise at the mine site.
5. Will the mining operations be conducted in such a way so as to mitigate adverse impacts on the public and neighboring properties from noise? (CBJ 49.65.135(4))
Yes. The proposed project, with the conditions recommended below, will minimize adverse noise impacts at the project site and along the helicopter flight path. See mitigating measures identified in Finding No. 4.
STAFF RECOMMENDATION
Staff recommends that the following conditions be included in the large mine permit to mitigate adverse impacts from noise:
2. Unless weather, safety procedures, emergencies, or FAA requirements dictate otherwise, the mine operator shall operate helicopters at elevations and along the flight path, as follows, in order to minimize noise levels on residential areas, recreation users, and wildlife:
b. The flight path shall be: from the Juneau Airport, head west while immediately climbing to the FAA-directed or highest practical altitude, cross the Mendenhall River, turn north to Montana Creek and then proceed northwest following the creek drainage, on past Windfall Lake toward the mouth of Cowee Creek, north across Berners Bay, and then along the coastline of Lynn Canal to the mine site.
1. Hart Crowser conducted a similar noise analysis for the CBJ in 1990-91 for the previous Kensington project proposal.
2. U..S. Forest Service, Final Environmental Impact Statement for Helicopter Glacier Tours (1995), page 1-7, citing FAA Circular AC91.36C dated March 19, 1982.
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