MWDF - The operating noise was assumed to be produced by two trucks at
the boundary nearest
    each noise-sensitive location. Six different locations were used for
the contour calculations.

    Access Road - The noise levels were calculated by estimating the number
and types of vehicles
    that would be traveling along the road during the morning, afternoon
and nighttime periods. The
    noise source location for the access road was chosen at the point along
the road that is nearest
    to each noise-sensitive location. Four different locations were used
in the contour calculations.

    Railroad spur - The railroad spur operation noise level was obtained
from the mine/mill noise
    contours. The noise source was located at the northeastern end of the
spur.

    Haul Road - The haul road was assumed to have three heavy trucks traveling
at the midpoint of
    the road.

    Pipelines (Tailings Transport and Water Discharge) and Discharge Structure
- The tailings
    transport pipeline, water discharge pipeline, and water discharge structure
were assumed to have
    no operating noise because they are located underground or in an enclosure.

Total noise during winter operations would be less than summer operations
(Table 3-29). This is due
to lower baseline noise levels during the winter. There would be an increase
of 1 dB or less in
day-night noise levels at Locations 1, 4, 7 and 10. Increases between 1 dB
and 4 dB at Locations 2, 3,
8 and 9 are predominantly due to the MWDF. At Location 6, the haul road and
the MWDF would
contribute to sound levels. Day-night noise levels increase 10 dB and 8 dB
due to the MWDF and haul
road at Location 5 and 6, respectively.

Residents near Locations 3, 5 and 6 would experience 9 dB, 10 dB and 20 dB
increases, respectively,
in winter nighttime sound levels. All other locations would experience noise
levels increases up to 6
dB or less. Nighttime sound levels change substantially during a worst case
analysis at Location 6 due
to the existing low background sound levels. Actual sound levels during operations
are expected to be
lower.

There would be little or no change (less than one dB) in background day-night
sound levels in the
summer at Locations 1 through 4 and 7 through 10 due to project operation.
At Location 5, a change
of about 3 dB is anticipated, predominantly due to MWDF activities. At Location
6, there is a change
of about 4 dB, principally due to the haul road. The estimated noise levels
would probably be lower
during most of the actual operations. Summer nighttime noise levels increase
20 dB at Location 5.
AUl other locations increase 5 dB or less.

The overall increase in sound levels at Locations 5 and 6 is, under a worst
case analysis, above 10 dB



omplaints or community action. Construction noise would occur over a 30 month
test period of noise generation during the first two years. Operation noise
illy greatest during the winter months at night. The overall human response
to
I be very similar to those discussed in the section on construction impacts.
Noise
Ltion would last for longer periods of time and would continue over the 29-year


Plan Impacts - The noise management plan as proposed by Exxon should reduce
e. The plan' s effectiveness, however, depends upon the enforcement and active
)us provisions. For instance, speed limits need to be posted and enforced,
be maintained, and work scheduling to avoid week and nighttime activity would
iing. Since the DNR does not have enforcement authority on noise issues,
local
e to pursue noise management issues with Exxon and the appropriate


Impacts - The project would produce some noises that are instantaneous in
oration of these noise sources is similar to that of intermittent auto, snowmobile,



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