DERR-2025-006054

6952 South High Tech Drive, Suite B
Midvale, Utah 84047
P [phone]
Terracon.com
Facilities | Environmental | Geotechnical | Materials 1

May 15, 2025

Salt Lake City Corporation
451 S. State Street Rm 425
P.O. Box 145460
Salt Lake City, Utah 84111

Attn: Mr. Logan Hunt
Real Estate Services Director
P: [phone]
E: [e-mail]

RE: Observation of Environmental Conditions
Building Demolition Site Inspections
Fleet Yard Block - 300 West 900 South Block
Salt Lake City, Utah 84101

Dear Mr. Hunt:

This correspondence is provided to document observations of environmental conditions relating to
the recent building demolition and debris removal at the above-referenced site.

Terracon Consultants, Inc. (Terracon) was retained to perform site inspections at the Fleet Yard
Block facility to document areas of potential environmental concern including oil/water
separators, sumps, and floor drains. Prior to the seven buildings being razed, Terracon reviewed
historical reports that documented the on-site features which were determined to have potential
for releases of hazardous substances to the environment during and after the demolition and
removal of building materials. Exhibit 1 depicts the locations of these features relative to the
former building locations. An aerial overview of conditions with localized temporary ponding after
a significant rainfall event is included as Exhibit 2. A photo log of observations is also attached.

Initial Observations
Demolition activities were initiated during the week of March 17, 2025 with a current anticipated
completion of approximately May 23, 2025. Throughout the demolition debris removal process,
Terracon conducted multiple site visits to observe the site activities and condition of the sumps,
floor drains, oil/water separators, wash-bay drains, exterior storm drains, and low lying areas.
During this time, Terracon noted generally good housekeeping, active dust control measures,
proper placement of sediment control features and/or wattles on storm drains, and caution to
avoid damage to the drains and sumps. Due to limited rainfall events in March and April, minimal
changes or effects to the site features were observed.

Observation of Environmental Conditions
Fleet Yard Block | Salt Lake City, Utah
May 15, 2025 | Terracon Project No. 61257048

Facilities | Environmental | Geotechnical | Materials 2

Significant Rainfall Event Observations
A significant rainfall event occurred from May 5 to May 6, 2025, with approximately one inch of
rainfall in a short period of time. Terracon mobilized to the site the morning of May 6, 2025 to
observe and document the effects of this rain event. Terracon observed that the functioning and
water depth of the sumps, oil/water separators, and storm drains generally remained in the same
condition and appeared unaffected. Surface water outside the building footprints flowed to and
collected in the south-central area of the site (see Exhibit 2), away from drains and features with
the potential for environmental release. Terracon observed that the trench floor drain in the
footprint of the northeast building (second from the north) was significantly backed up and the
trench floor drain in the north building footprint was silt-filled with only a small area of ponded
rainwater. Excess water along the approximately 65-foot long trench drain near the northeast
corner of the site had overflowed the drain resulting in a large area of ponded standing rainwater
on the pavement. The ponded rainwater did not extend beyond the concrete slab-on-grade floor;
however the lack of drainage indicates that the potential remains for the release of the backed up
contents onto the ground surface and potentially into the storm drains in the parking area.
Terracon contacted the Salt Lake City Corporation (client) and XCEL General Contractors who
were conducting the debris removal to notify them of the situation. Terracon returned to the site
on May 7, 2025, approximately 24 hours after the conclusion of the rain event, to observe the
site condition. At that time, the previously backed-up rainwater around the trench drains in the
north and northeast buildings had completely drained and was no longer present. The standing
water in the central area of the former parking area had decreased but was still present.

Above-ground Storage Tanks
In addition to the potential of an environmental release from the sub -grade drainage features,
Terracon has also been monitoring the status of three above-ground storage tanks (ASTs) which
were removed from the northeastern building prior to demolition. Tw o of the three ASTs contain
up to half of the volume of liquid remaining. These two ASTs appear to be in good condition;
however they are stored on the gravel surfaced lot without secondary containment. Their stored
location is shown on Exhibit 2.

Recommendations
Based on observations of the site throughout the demolition and debris removal process, Terracon
provides the following recommendations:
◼ Remove and properly dispose of the sediment and debris from the trench drains, specifically
the north and northeast drains observed to have a low drainage rate, to allow for better flow.
Terracon recommends also cleaning out the other floor drains as a preventative measure as
they were observed to have significant sediment.
◼ The oil/water separators appear to be functional with consistent depth of fluids through the
dry periods and rain event. The oil/water separators are not required to be cleaned out at this
time but should be inspected regularly to confirm the functionality of the system.
◼ During and after significant rainfall events, continue to monitor the sumps, floor drains,
oil/water separators, wash-bay drains, and exterior surface drains for backups, overflowing, or
changes in condition.
Observation of Environmental Conditions
Fleet Yard Block | Salt Lake City, Utah
May 15, 2025 | Terracon Project No. 61257048

Facilities | Environmental | Geotechnical | Materials 3

◼ Continue to maintain the wattles and other sediment controls on the exterior surface storm
drains and floor drains.
◼ Continue to monitor the standing surface water on the south -central parking area to ensure
that the extent of standing water does not encroach on the oil/water separators and sumps .
◼ Remove and properly dispose of the contents of the ASTs to mitigate the potential of a future
release onto the gravel-surfaced area and potentially into storm drains. Maintain
documentation of the final disposition of these fluids once removed from the site.
We are prepared, upon request, to conduct additional inspections on an as needed basis to
document site conditions. Upon request, Terracon is also available to meet with the client and
onsite personnel to review the current conditions and discuss what features need continued
monitoring. Should you have any questions or comments please contact us at your convenience.

Sincerely,
Terracon Consultants, Inc.

Stephen Maliszeski Andy King
Project Manager Senior Project Manager
Authorized Project Reviewer

Attachments:
Site Exhibits
Exhibit 1 –Features of Environmental Concern
Exhibit 2 – Aerial Overview May 7, 2025
Photo Log

Features of Environmental Concern
Fleet Yard Block Cleanup Monitoring
325 W 900 S
Salt Lake City, UT 6952 S High Tech Dr, Ste B Midvale, UT 84047-3772
61257048
(not defined)
May 8, 2025
Project No.
Scale:
Client:
Date: 1
Exhibit
Salt Lake City Corporation
LEGEND
Trench floor drain

Oil/water separator

Sumps / wash-down

Locations are approximate and should
not be used for construction purposes.

Aerial Overview May 7, 2025
Fleet Yard Block Cleanup Monitoring
325 W 900 S
Salt Lake City, UT 6952 S High Tech Dr, Ste B Midvale, UT 84047-3772
61257048
(not defined)
May 8, 2025
Project No.
Scale:
Client:
Date: 2
Exhibit
Salt Lake City Corporation
LEGEND
Approximate area of rainwater
ponding near floor drains.

Approximate maximum extent of
surface water ponding from rain
event.

Aerial imagery from Terracon
Drone: May 7, 2024
Temporarily
relocated ASTs
Site Photographs
Fleet Yard Block | Salt Lake City, Utah
Date Photos were taken: March 21 to May 7, 2025 | Terracon Project No. 61257048

Facilities | Environmental | Geotechnical | Materials

Photo #1 View of demolition activities. View
looking north. March 21, 2025.
Photo #2 View of demolition activities. View
looking northeast. March 21, 2025.

Photo #3 View of demolition activities. View
looking southeast. March 21, 2025.
Photo #4 View of wash down area drains with
waddles. View looking southeast toward the
center of the site. May 2, 2025.

Photo #5 View of an oil/water separator near
the wash-down area. May 2, 2025.
Photo #6 View of the trench floor drain in the
northeast corner of the site. View looking east.
May 2, 2025.
Site Photographs
Fleet Yard Block | Salt Lake City, Utah
Date Photos were taken: March 21 to May 7, 2025 | Terracon Project No. 61257048

Facilities | Environmental | Geotechnical | Materials

Photo #7 View of a sump located in the
southern portion of the site. View looking to the
south. May 2, 2025.
Photo #8 View of a sump located in the
southeastern portion of the site. View looking
north along the eastern boundary. May 2, 2025.

Photo #9 View of sub-grade mechanic pit in the
north building. View looking east. May 2, 2025.
Photo #10 View of the trench floor drains in the
north building. View looking due north. May 2,
2025.

Photo #11 Representative view of surface storm
drain sediment control covers. View looking east.
May 2, 2025.
Photo #12 View of the above ground storage
tanks relocated from the northeast building. View
looking east. May 2, 2025.
Site Photographs
Fleet Yard Block | Salt Lake City, Utah
Date Photos were taken: March 21 to May 7, 2025 | Terracon Project No. 61257048

Facilities | Environmental | Geotechnical | Materials

Photo #13 View of the central parking area with
ponded surface drainage following major rain
event. View looking northeast. May 6, 2025.
Photo #14 View of the northeast ponded
rainwater in the trench floor drain following major
rain event. View looking east. May 6, 2025.

Photo #15 View of the northeast sediment filled
floor drain with ponded rainwater after major rain
event. View looking north. May 6, 2025.
Photo #16 View of the north building floor drain
with minor rainwater ponding after major rain
event. View looking north. May 6, 2025.

Photo #17 Representative view of a surface
stormwater drain after the major rain event. View
looking southeast. May 6, 2025.
Photo #18 View of the northeastern most trench
floor drain after the major rain event. View looking
northeast. May 6, 2025.

Site Photographs
Fleet Yard Block | Salt Lake City, Utah
Date Photos were taken: March 21 to May 7, 2025 | Terracon Project No. 61257048

Facilities | Environmental | Geotechnical | Materials

Photo #19 View of northeast trench floor drain
which had ponded rainwater 24-hours after major
rain event. View looking east. May 7, 2025.
Photo #20 View of north building trench floor
drain which had ponded rainwater 24-hours after
major rain event. View looking east. May 7, 2025.

Photo #21 View of central surface drainage 24-
hours after major rain event. View looking east.
May 7, 2025.
Photo #22 View of site conditions. View looking
north. May 7, 21024.