Exxon' s plan, in essence, is a tiered system of responses to impacts as
they appear. The first tier
consists of measures installed during the construction phase because of the
sensitivity of these
waterbodies to groundwater drawdown and the probable occurrence of impacts.
The second tier or
operations phase mitigation measures would be installed as needed. Thus,
operations phase facilities
only would be added if and where impacts developed. The glacial aquifer intercept
system represents
the third tier and could supply groundwater to the majority of sites.

This plan strives for maximum flexibility especially in terms of instituting
the measures proposed for
either the operations phase or the glacial aquifer interceptor system. For
example, a portion of the
interceptor well system might be placed in the glacial aquifer above the
mine. This water could then
be used for mitigating impacts to Swamp Creek thus reducing the need for
installing mitigation wells
C-3 and C-4. Other configurations of these two systems also would be possible
if agreeable to Exxon
and the DNR.

                                   NOISE MANAGEMENT PLAN

Two types of mitigative controls would be used to manage construction, operation,
and reclamation
sounds (noises) at the project site. The first type, administrative controls,
would modify operating
procedures or work practices to reduce, eliminate, or shorten the duration
of the noise source. This
type of control is most effective for transient sources such as operating
procedures. The second type
would be engineering controls which physically change specific noise sources.
This type of control
may take the form of source relocation, source replacement and source modification
(e.g., addition of
a muffler to a diesel engine). A brief description of these control measures
is presented below:

Administrative

    1)   Posting of speed limits;

    2)   Limiting tree removal to maintain sound barriers;

    3)   Limiting engine idling of mobile equipment during periods of inactivity;

    4)   Limiting certain activities to daytime hours, where feasible. Such
activities will include:
          surface facility contruction (including MWDF), site grading and
waste haulage. It must be
          recognized, however, that certain circumstances may result in periodic
nighttime
          activities; and

    5)   Movement of trains by the Soo Line on the spur will normally occur
during the daytime.
          However, concentrate loading occurs continuously, so there will
be some movement and
          placing of rail cars within the plant area at night.

Engineering

    1)   Proper equipment maintenance and the use of mufflers on all internal
combustion engines;

    2)   Ore processing equipment, air compressors and emergency electrical
generators would be
          contained within buildings or other enclosures;

    3)   A criterion used in mine ventilation and heating fans selection
would be overall sound
          power level. Discharging structures would be directed vertically
to reduce noise levels
          off-site.

    4)   Noise associated with shaft blasting would be reduced by closing
the shaft doors and
          because of the depth (70-170 feet).



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