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SOIL EXCAVATION & HAZARDOUS MATERIALS HANDLING

Client Furnace Creek
Location Cottage Grove, Oregon
Scope Of Work Restoration
Schedule September 20, 2018

In 2018 EQM completed the excavation, backfill, and restoration of Furnace Creek
at the Black Butte Mine site. The Black Butte Mine (BBM) is a former mercury
mine located in southern Lane County, Oregon in the Coast Fork Willamette River
basin, approximately ten miles south of Cottage Grove, Oregon. The primary
features of the site included: mine waste piles consisting of waste rock and mill
tailings, a former mill structure containing a rotary kiln, mercury condenser, and
ore storage/crushing equipment (New Furnace Area), an additional mill and
furnace area (Old Ore Furnace Area), several dilapidated buildings, a system of
unimproved roads, and mine adits

The removal action was intended primarily to reduce the off-site migration of
mercury from mill tailings to adjacent creeks (Dennis Creek and Furnace Creek)
and downstream waterways. EQM mobilized a crew and equipment to the site and
began excavation of Furnace Creek on May 28, 2018. During this period,
approximately 750 feet of soil/sediment from Furnace Creek was excavated and
placed into the on-site repository. In addition, a borrow source area was cleared of
vegetation in preparation to remove clean material for the restoration of Furnace
Creek.

At the end of June, EQM completed the excavation of Furnace Creek having
excavated over 12,000 cubic yards of mercury- and arsenic-contaminated tailings.
Restoration of Furnace Creek began on July 9th and involved backfilling the
over-excavated channel to original grade. After backfilling was complete, a new
stream channel was constructed for Furnace Creek along with restoration of the
steep slopes of a ravine. Many engineered rock waterfall features had to be
constructed in the stream channel to prevent erosion that would be caused by the
steep grade of the stream.

After the restoration of the Furnace Creek was completed, restoration of the
borrow area was started which included regrading steep slopes; installing a rock
stream channel for a small seasonal drainage; grading the remaining topsoil over
the disturbed area; placing logs, wood chips, and slash material for erosion
control; and hydroseeding the area with a native seed mix.

After all the material was placed into the on-site repository, it was graded to a 3 to
1 slope and capped with clean material. A ditch was excavated around the
repository to collect stormwater runoff in a settling pond and a small creek was
also diverted around the repository. Contaminated logs and stumps were placed
on top of the repository for erosion control. Finally, the old furnace area (where
mercury ore was processed) was capped with clean fill and hydroseeded to
prevent erosion and potential migration of the mercury and arsenic.

Using a highly experienced field crew, EQM was able to complete the project well
within the dry season and substantially under budget.

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