2650 north 180 east lehi, Utah 84043 Telephone number 801-400-9784

GEOTECHNICAL ENGINEERING STUDY

Geyser Peak Communication Tower

Latitude 38.512061° N., Long. -111.460159° W.

Sevier County, Utah

PREPARED FOR:

Mr. Travis Sylvester Radio Project Manager

Utah Communications Authority 5215 Wiley Post Way #550 Salt Lake City, Utah 84116

April 23, 2026

Project No. 26018

2650 North 180 East Lehi, Utah 84043 P. 801-400-9784

April 23, 2026

Mr. Travis Sylvester Radio Project Manager Utah Communications Authority 5215 Wiley Post Way #550 Salt Lake City, Utah 84116

SUBJECT: GEOTECHNICAL ENGINEERING STUDY

Geyser Peak Communication Tower

Lat. 38.512061° N., Long. -111.460159° W.

TG Project No. 26018

Dear Mr. Sylvester:

Enclosed are the findings of the geotechnical engineering study performed for the above-referenced property. Geotechnical engineering recommendations for foundation analysis are presented herein.

Please feel free to contact us should you or members of the design team have any questions or desire additional information. The opportunity to be of service on this project is appreciated.

Respectfully submitted, Taylor Geotechnical

This report is not valid without a digital signature noted.

Alanson O. Taylor, P.E.

Principal

Geotechnical Engineering Study April 23, 2026 Geyser Peak Communications Tower TG Project No. 26019 Piute County, Utah

TABLE OF CONTENTS

1.0 INTRODUCTION

2.0 SCOPE OF WORK

2.1 Subsurface Exploration

2.2 Laboratory Testing

2.3 Engineering Analyses and Report

3.0 SITE CONDITIONS

3.1 General

3.2 Geology

3.3 Subsurface Materials

3.4 Subsurface Water

3.5 Subsurface Variations

4.0 FOUNDATION ANALYSIS RECOMMENDATIONS

4.1 Tower Foundation Support

4.2 Foundation Support for Auxiliary Equipment

4.3 Estimated Settlement

4.4 Footing Excavations

4.5 Resistance to Lateral Loads

4.6 Seismicity

4.7 Structural Fill

4.8 Surface Drainage

5.0 CLOSURE

APPENDIX

Figure 1 Vicinity Map Figure 2 Site Plan and Site Photo Figure 3 Regional Geologic Map Figure 4 Test Pit No. TP-1 Log Figure 5 Test Pit Photos Figures 6a & 6b Seismic Output Data Sheets Figure 7 Direct Shear Test Results

Piute County, Utah Page 1 of 6

1.0 INTRODUCTION

This report presents the results of the geotechnical engineering study performed for a proposed communication tower to be located 1.3 miles southeast of Geyser Peak and 12.5 miles northeast of Loa, Sevier County, Utah, at Latitude 38.512061 degrees, Longitude -111.460159 degrees. The general location of the tower site is shown on Figure 1, Vicinity Map in the Appendix. The purpose of the study was to evaluate the nature and engineering properties of subsurface materials at the site and provide geotechnical engineering recommendations for the design of the proposed communication tower foundation.

Based on the information provided by Utah Communications Authority, the following aspects of the project were considered in our study:

1. Final grades will be approximately the same as existing grades.

2. The proposed tower will be constructed on a concrete mat foundation with the bottom of the foundation located below the existing grade.

3. Tower will consist of a self-supporting lattice tower about 100 feet in height.

4. A new accessory equipment building will be located adjacent to the tower. The building will be supported on a square monolithic foundation or spread footings with a slab on grade floor.

If aspects of the project vary from those described above, Taylor Geotechnical should be notified immediately so the applicability of the recommendations presented herein can be evaluated.

2.0 SCOPE OF WORK

This study included the following scope of work.

2.1 Subsurface Exploration

One (1) exploratory test pit was excavated at the site to evaluate subsurface conditions. The exploratory test pit extended about 11 feet below the existing ground surface. The test pit location is shown in Figure 2, Site Plan and Site Photo, in the Appendix.

Subsurface conditions observed in the exploratory test pit TP-1 were carefully documented at the time of excavation by Taylor Geotechnical field personnel. The log of test pit TP-1 is provided in Figure 4 in the Appendix. Disturbed samples of representative soils were obtained for laboratory testing and visual classification. Undisturbed samples could not be obtained due to the granular nature of the subsurface materials. Subsurface materials were classified in general accordance with the Unified Soil Classification System (ASTM Method D 2487).

Piute County, Utah Page 2 of 6

The test pit was backfilled without compaction. The test pit backfill should be removed and replaced in compacted lifts if it affects the foundation.

2.2 Laboratory Testing

Soil samples obtained from the test pits were tested in the laboratory to aid in classification and to determine pertinent engineering properties. These tests included:

•Moisture Contents;

•Gradations; and •Direct Shear Test.

Results of the laboratory tests are shown on the Test Pit log, Figure 4 as well as graphical results of the direct shear test in Figure 7, in the Appendix.

2.3 Engineering Analyses and Report

Data obtained from the exploratory test pit was evaluated. Geotechnical engineering analyses were performed which included preparation of this report presenting the findings and recommendations developed during the study.

3.0 SITE CONDITIONS

Existing surface and subsurface conditions associated with the property are presented in this section.

3.1 General

The surface of the proposed communication tower area slopes downward to the east and south at about a 17 percent grade. The gradient of the surface steepens east of the subject site. Vegetation at the tower site is minimal and comprised of native weeds and grass. Access to the site is from a small single lane dirt road located west of the site. The site is situated at about elevation 9,610 feet above mean sea level and is located at geographic coordinates North 38.512061° latitude, West 111.460159° longitude.

3.2 Geology

The Utah Geologic Survey1 has mapped the surface of the site as Qapcv defined as alluvial pediment-mantle and colluvial deposits with volcanic clasts (early Holocene to middle Pleistocene); boulders, gravel, sand, silt, clay, and may locally include talus; similar to Qap

1 Robert F. Biek, 2023, Geologic Map of the West Half of the Loa 30' x 60' Quadrangle, Garfield, Piute, and Wayne Counties, Utah. M-292DM. UGS. 1:62,000 scale.

Piute County, Utah Page 3 of 6 deposits, but contain significant quantities of rounded vesicular volcanic boulders; covers bedrock surfaces between drainages at various levels above local base level; include associated colluvial deposits formed as the pediment flanks erode; colluvial deposits more pronounced on the upper parts of the pediment surface; Qapcv contains significant landslides not mapped separately near Geyser peak; commonly less than 15 meters thick (50 feet). A regional geologic map is shown in Figure 3 in the Appendix.

The materials observed in the test pit are consistent with the surface geology on the regional geologic map.

No active faults cross the subject area and no landslide deposits are within the subject tower site but a landslide is located to the east of the subject site as noted on Figure 3.

3.3 Subsurface Materials

The subsurface soils consisted of 4 inches of topsoil underlain by 4 feet of medium dense poorly graded sand with clay and gravel underlain by 6 feet of poorly graded sand with gravel extending beyond the depth investigated of 11 feet. The side walls of the test pit caved during excavation activities when the side walls were 10 feet in height. A more detailed description of the subsurface conditions can be found in Figure 4, Test Pit Log TP-1 in the Appendix. Photographs of the test pit are shown on Figure 5 in the Appendix.

3.4 Subsurface Water

Groundwater was not observed at the time of our subsurface exploration and is not expected to impact construction. Seasonal fluctuations in groundwater conditions do occur, and groundwater fluctuations of several feet are not unusual. Numerous factors contribute to groundwater fluctuations such as seasonal recharge, regional and local irrigation, and periods of heavy precipitation. The detailed evaluation of these and other factors which may be responsible for groundwater fluctuations is beyond the scope of this study.

3.5 Subsurface Variations

Based on the results of the subsurface exploration and our experience, variations in the continuity and nature of subsurface conditions should be anticipated. Due to the nature and depositional characteristics of soils documented at the site, care should be taken in interpolating or extrapolating subsurface conditions beyond the exploratory test pit.

4.0 FOUNDATION ANALYSIS RECOMMENDATIONS

Proposed foundation recommendations are provided in this section. The proposed communication tower may be supported on a large mat foundation. The proposed auxiliary equipment building may be supported on shallow strip footings or a monolithic foundation. Details for foundation support follow.

Piute County, Utah Page 4 of 6

4.1 Tower Foundation Support

The mat foundation should have minimum dimensions as required to resist downward and overturning loads imposed by the tower. Estimated foundation widths range from 7 to 15 feet.

The foundation may be supported directly on undisturbed granular soils or on compacted structural fill extending to undisturbed granular soils. The foundation may be designed using a maximum allowable bearing capacity of 6,000 pounds per square foot (psf) if a minimum of 7 feet in width.

This allowable bearing value is for total dead load and frequently applied live loads and may be increased 33% for short durations of loading which will include the effect of wind or seismic forces.

Disturbance of the subgrade at the base of the excavation should be expected due to the granular nature of the subgrade materials. Prior to place of the forms for concrete or structural fill, the subgrade at foundation grade should be compacted to a non-yielding surface with a vibratory plate compactor or compaction wheel on the trackhoe.

4.2 Foundation Support for Auxiliary Equipment

A maximum allowable bearing pressure of 3,000 psf is recommended for foundation design of the auxiliary equipment building using strip footings or a monolithic foundation supported on the undisturbed granular soils or on compacted structural fill extending to undisturbed granular soils.

The proposed footings may also be supported on 6 inches of granular road base underlain by 24 inches of 100 percent crushed gravel with a maximum particle size 1.5 inches and contain less than 5 percent passing the No. 40 sieve. The depth of gravel is required in order to provide a non-frost susceptible fill. The crushed gravel should be compacted during placement with at least 4 passes of a vibratory plate compactor. The road base should be compacted to at least 95 percent of the modified Proctor as per ASTM D 1557. Filter fabric should be placed between the native soils and gravel fill.

Individual or spread (column) footings for the auxiliary equipment pads should be at least 18 inches wide and extend at least 40 inches below grade for frost protection if not supported directly on competent bedrock.

The allowable bearing value is for total dead load and frequently applied live loads and may be increased 33% for short durations of loading which will include the effect of wind or seismic forces. This bearing value may be increased 33% for short durations of loading which will include the effect of wind or seismic forces.

4.3 Estimated Settlement

Using the anticipated bearing values indicated above, the estimated maximum post-construction settlement will be less than 1-inch for the tower foundation and conventional shallow spread and/or continuous footings. The maximum differential settlement between foundation elements is

Piute County, Utah Page 5 of 6 estimated to be approximately one-half of the total settlement. Estimated settlements are based on the assumption that foundation subgrades are prepared as specified in Section 4.4 Footing Excavations.

4.4 Footing Excavations

Footing excavations can be accomplished with conventional excavation equipment. Rock excavation techniques, such as ripping, will not be required. The base of the excavation should be cleared of all loose materials and compacted to a non-yielding surface prior to placement of concrete. We recommend that Taylor Geotechnical observe all footing excavations prior to placement of structural fill, steel, and concrete to verify that all deleterious and/or soft materials have been removed; that footing subgrades consist of undisturbed native soil, and that the recommendations presented herein have been appropriately interpreted.

4.5 Resistance to Lateral Loads

Resistance to lateral loads can be provided by friction acting at the base of foundations and by passive earth pressure against the foundations. For footings supported on native granular soils or compacted structural fill, we recommend using a coefficient of friction of 0.43. The coefficient of friction times the normal load may be assumed to act horizontally at the base of the footing.

Passive pressure from properly compacted granular backfill against the sides of footings can be calculated on the basis of an equivalent fluid weighing 340 pounds per cubic foot (pcf). The passive pressure should be reduced using the appropriate factor of safety.

The recommended coefficient of friction and passive pressure values are based on mobilization of the ultimate soil strength. Suitable factors of safety should be included in the design to limit the strain which will occur at the ultimate strength, particularly in the case of passive resistance. The top 30 inches of backfill should be neglected for passive resistance calculations.

4.6 Seismicity

The site is situated in a seismically active region. Ground shaking resulting from earthquakes associated with nearby and distant faults will occur. During the life of the project, seismic activity associated with active faults in the area has the potential to generate moderate to strong ground shaking at the site.

Based on experience with similar sites in Utah and limited subsurface exploration, the site is likely best represented by Site Class D (2021 International Building Code).

The following spectral design response spectrum coefficient should be used for seismic design.

Short Period Spectral Response Design Acceleration, SDS = 0.43g One Second Period Spectral Design Acceleration, SD1 = 0.23g

Modified Peak Ground Acceleration, PGAM = 0.27g.

Piute County, Utah Page 6 of 6

4.7 Structural Fill

If required for construction of the mat foundation or auxiliary equipment foundations, import structural fill should have a maximum particle size of 4 inches and less than 20 percent passing the No. 200 sieve. The fill should be compacted to at least 95 percent of the modified proctor as per ASTM D1557 in 8-inch lifts. Compaction testing using a nuclear gauge should be completed at a minimum of every other lift.

The native soils below the topsoil may be used as structural fill if the rocks larger than 4 inches in diameter are screened out of the fill prior to placement and compaction.

Structural fill used for foundation support should extend horizontally an additional one foot horizontally beyond the perimeter of the foundation for every vertical foot of fill thickness.

4.8 Surface Drainage

Providing positive site drainage during development will be fundamental to the stability and long-term performance of the proposed structures. Adequate positive drainage for water flowing off of the site is critical and should be provided.

Positive drainage should be provided away from the foundation areas to prevent infiltration beneath the structures and to reduce percolation of water into foundation soils. The ground surface surrounding the exterior of the structures should be sloped to drain away from the structure in all directions.

5.0 CLOSURE

The findings and recommendations of this report were prepared in accordance with generally accepted professional geotechnical engineering principles and practice in this area of Utah at this time. There is no other warranty, either express or implied.

The conclusions and recommendations presented herein are based on the results of limited subsurface exploration and laboratory testing, combined with interpolation and extrapolation of subsurface conditions between and beyond exploration locations. Subsurface conditions may differ in some locations from the conditions observed in the exploration and may require additional analyses and possibly modified recommendations.

This report was written for the exclusive use of the Utah Communications Authority and only for the subject project described herein. Taylor Geotechnical is not responsible for technical interpretations by others of exploratory information which has not been described or documented in this report. Specific questions or interpretations concerning the findings and conclusions presented herein may require written clarification to avoid possible misunderstandings. The opportunity to be of service on this project is appreciated.

Geyser Peak Communication Tower TG Project No. 26018

APPENDIX

FIGURES

Project No. 26018 Geyser Peak Communication Tower Lat. 38.512061°, Long. -111.460159°

Sevier County, Utah

VICINITY MAP

Figure No. 1

Subject Site Looking West.

SITE PLAN AND SITE PHOTO

TP-1

Figure No. 2

0 250 ft. 125 ft.

SCALE Reference: Google Earth (2026)

Geyser Peak Communication Tower Lat. 38.512061°, Long. -111.460159° Sevier

County, Utah

REGIONAL GEOLOGIC MAP

0 2,500 ft. 1,250 ft.

SCALE

Qapcv: Alluvial pediment-mantle and colluvial deposits with volcanic clasts (early Holocene to middle Pleistocene); boulders, gravel, sand, silt, clay, and may locally include talus.

Qms: Mass-movement landslides and slumps (Holocene to middle Pleistocene); large coherent blocks to fragmented masses of bedrock and surficial debris of poorly sorted mud, sand, and angular broken rock.

Tr: Shoshonitic volcanic rocks of Riley Spring (late Oligocene); poorly exposed, red-brown to gray, porphyritic flows consisting of about 35 percent phenocrysts of plagioclase, augite, olivine, iron-titanium oxide, and trace amounts of orthopyroxene in a matrix of olivine, iron titanium oxides, plagioclase, and glass or sanidine.

Tv: Interbedded trachyte ash-flow tuff and volcanic-clast conglomerate (late Oligocene); red-brown to gray, highly jointed, weakly porphyritic trachytic flows interbedded with volcanic pebbles and cobbles.

Reference: Doelling, Hellmut H. (2016)

SITE

Figure No. 3

Geyser Peak Communication Tower Lat. 38.512061°, Long. -111.460159°

Sevier County, Utah

Qapcv

Qa

Tv Tbgp

Ql

CLIENT:

SITE LOCATION:

JOB NO.:

m

PROJECT:

GROUNDWATER LEVEL:ELEVATION: 9607

Lehi, Utah 84043

DEPTH

ft.

D ry

D en si ty

(p cf

M oi st ur e

Sa m pl e

G ra ve l (

In de x Pl as tic ity

Li m it Pl as tic

Li m it Li qu id

Sa nd

Fi ne s

Gradation Atterberg Limits

FIELD DATE:

EQUIPMENT:

LOGGED BY:

LATITUDE:-111.460159 LONGITUDE:35.512061

U

SC

S

G ra ph ic

L og

SOIL DESCRIPTION

TEST HOLE NO.:

2650 North 180 East

Bl ow

C ou nt s

0 40

Telephone: 801-400-9784

Grab Sample

TY

PE

SA

M

PL

E

California Sampler

Dames and Moore

SPT sampler

3.25" O.D./2.42" I.D. "U" Sampler

NOTES:

Figure No.:

Shelby

Geyser Peak Communication Tower 26018 Lat. 38.512061, Long. -111.460159 Utah Communications Authority

4-9-26 Kubota KX057-5

A.Taylor No Groundwater

TP-1

4.1

4.0

4.2

OL

SP-SC

SP

TOPSOIL: 4 inches, clayey sand with organics, loose, moist, dark brown.

POORLY GRADED SAND WITH

CLAY AND GRAVEL: Medium dense, moist, brown

POORLY GRADED SAND WITH

GRAVEL: Medium dense, moist, brown.

Friction Angle = 33.9 deg.

Cohesion = 390 psf

Bottom of test pit at 11 feet.

Test Pit TP-1, Looking at North Wall.

Test Pit TP-1, Looking at South Wall.

TEST PIT PHOTOS

Figure No. 5

Geyser Peak Communication Tower Lat. 38.512061°, Long. -111.460159° Sevier

County, Utah

Announcement ASCE 7-22 is now available.

Latitude, Longitude: 38.512061, -111.460159

Date 4/23/2026, 1:35:00 PM

Design Code Reference Document ASCE7-22

Risk Category IV

Site Class D

Type Value Description (Data) SS 0.49 The MCER spectral response acceleration at 0.2 seconds for Site Class BC, in units of g.

S1 0.13 The MCER spectral response acceleration at 1 second for Site Class BC, in units of g.

SMS 0.65

SMS = 1.5 x SDS, the Risk-Targeted Maximum Considered Earthquake (MCER) spectral response acceleration for short periods (of the two-period spectrum) and the user-specified Site Class.

SM1 0.34 SM1 = 1.5 x SD1, the MCER spectral response acceleration for 1 second (of the two-period spectrum) and the user-specified Site Class.

SDS 0.43 The design spectral response acceleration for short periods (of the two-period spectrum) and the user-specified Site Class, in units of g.

SD1 0.23 The design spectral response acceleration for 1 second (of the two-period spectrum) and the user-specified Site Class, in units of g

Type Value Description (Data Contd.)

SDC D Seismic design category

PGAM 0.27 PGAM, the Geometric-Mean Maximum Considered Earthquake (MCEG) peak ground acceleration for the user-specified Site Class, in units of g

TS 0.523 TS = SD1/SDS, in seconds, for construction of the two-period design spectrum

T0 0.105 T0 = 0.2 x TS, in seconds, for construction of the two-period design response spectrum

TL 6 TL, the long-period transition period, in seconds, for construction of the two-period design response spectrum

Figure No. 6a

Type Value Description (Underlying Data and Metadata) PGAuh 0.27 Probabilistic uniform-hazard (2%-in-50-years), geometric-mean peak ground acceleration, in units of g.

PGA84th Deterministic 84th-percentile, geometric-mean peak ground acceleration (without deterministic lower limit), in units of g.

VS30 260 The shear-wave velocity used for the user-specified Site Class, in units of m/s

Spatial Interpolation Method linearloglinear Identifier for spatial interpolation method used to obtain values for location of interest from underlying gridded values:

"linearloglinear" for bilinear of natural logarithm of values.

PGAdFloor 0.53 Deterministic lower limit peak ground acceleration (PGAG) for the user-specified Site Class, in units of g.

riskTargetedSpectrum Probabilistic risk-targeted, maximum direction response spectrum (for 1%-in-50-years collapse risk) eightyFourthSpectrum Deterministic 84th-percentile, maximum-direction response spectrum (without deterministic lower limit)

Figure No. 6b

Shear Strength by Direct Shear

Client Utah Communications Authority Project No. 26018 Project Gruett Residence Sample TP-1 6-7 ft.

Test Details Standard ASTM D3080 Particle Specific Gravity 2.65 – Assumed Sample Type Bulk Disturbed Sample Single or Multi-Stage Single Stage Lab. Temperature 70.0 deg.F Arbitrary Remold Sample Description Poorly Graded Sand with Gravel (SP) Gravel=26%, Sand=70%, Fines=4%

Gravel screened for direct shear sample.

Test Summary Reference A B C Normal Stress 6.95 psi 13.89 psi 27.79 psi Peak Strength 7.00 psi 12.56 psi 21.18 psi Corresponding Horizontal Displacement

0.0781 in 0.3081 in 0.2371 in

Residual Stress N/A N/A N/A Rate of Shear Displacement

Stage 1:

0.001500in/min

Stage 1:

0.001500in/min

Stage 1:

0.001500in/min

Final Height 0.9438 in 0.9641 in 0.9797 in Sample Area 4.90900 in2 4.90900 in2 4.90900 in2 Initial Wet Unit Weight 110.61 lbf/ft3 106.03 lbf/ft3 109.13 lbf/ft3 Initial Dry Unit Weight 104.44 lbf/ft3 100.15 lbf/ft3 103.07 lbf/ft3 Final Wet Unit Weight 131.93 lbf/ft3 123.89 lbf/ft3 123.68 lbf/ft3 Final Dry Unit Weight 110.67 lbf/ft3 103.87 lbf/ft3 105.21 lbf/ft3 Final Moisture Content 19.22 % 19.27 % 17.56 % Particle Specific Gravity 2.65 2.65 2.65 Final Void Ratio 0.4954 0.5932 0.5730 Final Saturation 102.79% 86.08% 81.21%

Figure No. 7