DERR-2024-011962

VCP/Brownfields Section - Site Visit Report

SITE NAME: Mayflower Mine

SITE LOCATION: Wasatch County

DATE OF SITE VISIT: 1 November 2024

PURPOSE OF SITE VISIT: DERR (David Bird) oversight of Phase 1 remedial action.

FIELD OBSERVATIONS: The DERR visited the Mayflower VCP site at ~9:50 am on 1 November to meet
with Extell (Kent Fawcett) personnel and observe conditions at the site. Current progress of the work to
address subsidence on the western portion of the Repository and the moving of the stormwater
detention pond further upstream in the Big Dutch Pete Hollow (BDPH) drainage were discussed, as was
a strategy to share files between the parties to finalize the Remedial Action Report.
The DERR and Extell discussed areas of the Repository that still need work in order to finalize the cover.
The Transit station has an area that will be covered with concrete within a week. There is a portion of
the southern end of the Repository that will be asphalted within a week. The DERR noted small areas of
the Repository set aside for vegetation, which Extell noted haven’t been planted yet, but have much
more thickness to the cover than the original design. These will have the decorative plantings at a later
date.
We then traveled to the western end of the Repository to examine work done for the subsidence there.
Roadbase material was placed there to bring this area up to grade in preparation for the replacement
asphalt cap/parking lot surface. The asphalt was placed recently and looks good. Extell indicated that
the asphalt cap extends at least five feet laterally beyond the waste rock boundary of the Repository and
survey nails will be placed at corner points and at regular intervals of straight or curved portions of the
waste rock boundary.
Extell has done the grading for the stormwater detention pond moved ~100 yards up the BDPH drainage
and away from the repository. Installation of the concrete structures for the spillway is next. This is
expected to be complete in about 3 weeks.
Additional silt removal is scheduled to be completed this fall in both the BDPH and McHenry drainage
areas.
The DERR left the site at ~11:55 am.
SPLIT SAMPLES COLLECTED: N/A
IS THE WORK BEING PERFORMED IN A MANNER CONSISTENT WITH THE ACCEPTED WORKPLAN?
Yes

Looking east at the southwestern end of the Repository where the grade of the parking lot/cover was
raised due to subsidence and new asphalt placed.

Looking south at the water bars built to direct drainage into the BDPH above the detention pond and the
Repository.

Looking west up the Glencoe Canyon drainage as it joins the McHenry Canyon drainage. This is the
siltation pond and outlet grate structure allowing drainage of the pond.

Looking southeast at the Glencoe Canyon siltation pond with the base of a ski lift and the MIDA Hotel in
the background.