Final_Geotechnical_Design_Report4rev.pdf

Terracon Consultants, Inc. 1392 13 t h Ave SW Great Fal ls, MT 59404 P [406] 453 5400 F [406] 761 6655 terracon.com

Geotechnical Design Report Rockfall Mitigation Project

Timpanogos Cave National Monument American Fork, Utah

June 17, 2016 Terracon Project No. C4155339

Prepare for:

A&E Architects, PC

Missoula, Montana

Prepared by:

Terracon Consultants, Inc.

Great Falls, Montana

6-17-16

Terracon Consultants, Inc. 1392 13 t h Ave SW Great Fal ls, MT 59404 P [406] 453 5400 F [406] 761 6655 terracon.com

TABLE OF CONTENTS

Page

INTRODUCTION ............................................................................................................. 01.0 FIELD EXPLORATION ................................................................................................... 12.0

2.1 Soil Profile

2.2 Groundwater

LABORATORY TESTING ............................................................................................... 33.0

3.1 Test Results

GEOTECHNICAL DESIGN CONSIDERATIONS AND RECOMMENDATIONS .............. 54.0

4.1 Rockfall Mitigation

4.2 Retaining Wall

SUBSURFACE CONDITION REVIEW – BUILDING SITES .......................................... 105.0

5.1 Visitor Center

5.2 Inter-Agency Center

PAVEMENT SECTION UT-92 ...................................................................................... 116.0 GENERAL COMMENTS ............................................................................................... 117.0

APPENDIX A – FIELD EXPLORATION

Exhibit 1 Site Location Maps Exhibit 2 Exploration Plans Exhibits 3 to 11 Boring Logs

General Notes Unified Soil Classification System

APPENDIX B – LABORATORY TESTING

Exhibit 12 Atterberg Limits Test Results Exhibit 13 to 14 Direct Shear Test Results

Soil Chemistry Test Results

APPENDIX C – SUPPORTING DOCUMENTS

Soil Nail Stability Analyses (12)

Geotechnical Design Report Rockfall Mitigation Project

Timpanogos Cave National Monument American Fork, Utah

IDIQ Contract No. P14PC00007 Terracon Project No. C4155339

June 17, 2016

INTRODUCTION1.0

The Visitor Center site is located in the narrow American Fork Creek Canyon along UT-92 (Alpine Loop Road) approximately 10 miles east of the interchange with I-15. Approximate coordinates of the site are N40º26’38”, W111º42’,19”, with a general elevation of 5635 feet. The primary geotechnical project elements include approximately 215 lineal feet of rockfall barrier and about 250 lineal feet of retaining structure across the toe area of the talus slope that rises above the site to the south.

This report presents the results of the Terracon geotechnical investigation and design conducted for the rockfall mitigation proposed in conjunction with the construction of a new Visitor Center at the Timpanogos Cave National Monument. The rockfall mitigation elements have been designed in substantial accordance with recommendations in the July 2013 Geotechnical Design Report prepared by the Central Federal Lands Highway Division (CFLHD), Geotechnical Services Branch. A geotechnical investigation was also previously conducted by Kleinfelder West, Inc. in 2011 for the original design of the Visitor Center building, pavements, and site development. In this report, some concern and initial input were provided relative to rockfall.

The CFLHD report provided recommendations for location, size, and energy rating of a rockfall barrier to be located near the toe of the talus slope. In association with the barrier, the project includes a new retaining structure that is required to gain additional parking for the facility; the proposed wall location will necessitate substantial cutting into the talus slope and will require slope stabilization measures for both construction and long-term service of the wall-barrier system. This report provides recommendations for design of soil nail support for the wall and a micropile foundation system for the rockfall barrier. The successful construction of these closely inter-related structures will require careful planning and execution by specialty contractors. The project also involves the relocation and reconstruction of UT-92 through the Visitor Center area to facilitate the planned improvements.

Rockfall Mitigation Project – Timpanogos Cave National Monument American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 1

The following report describes the Terracon field exploration, laboratory testing, and geotechnical analysis conducted for the project elements outlined above. This report also includes subsurface information for two borings conducted at the USFS-NFS Inter-Agency Center site located west of the canyon mouth. These discussions along with the supporting data in Appendices A and B plus the summary calculations included in Appendix C provide the basis for the geotechnical design recommendations presented herein.

FIELD EXPLORATION2.0

Seven soil borings, designated B-1 to B-7, were completed at the Visitor Center site as part of our field exploration program; boring depths ranged from 11½ feet to 26½ feet below existing site grade. Borings B-8 and B-9 were completed to depths of 20 ½ feet at the NPS-USFS Inter-Agency complex west of the canyon entrance. Locations of the borings are indicated on the attached Exploration Plans for each site in Appendix A. Boring locations were determined in the field during a meeting with the client, National Park Service and Terracon personnel. Final boring locations were adjusted to avoid utility conflicts following Blue Stakes of Utah and private utility locate services. The locations of the borings should be considered accurate only to the degree implied by the means and methods used to define them.

The drilling was conducted with a truck-mounted rotary rig using an air rotary/ODEX method to advance the borings. Samples of the soil encountered in the borings were obtained using the split barrel sampling procedures.

In the split-barrel sampling procedure, the number of blows required to advance a standard 2-inch O.D. split-barrel sampler the last 12 inches of the typical total 18-inch penetration by means of a 140-pound hammer with a free fall of 30 inches, is the standard penetration resistance value (SPT-N). This value is used to estimate the in-situ relative density of cohesionless soils and consistency of cohesive soils.

An automatic hammer was used to advance the split-barrel sampler in the borings performed on this site. A significantly greater efficiency is achieved with the automatic hammer compared to the conventional safety hammer operated with a cathead and rope. This higher efficiency has an appreciable effect on the SPT-N value. The effect of the hammer's efficiency has been considered in the interpretation and analysis of the subsurface information for this report.

The soil samples were tagged for identification, sealed to reduce moisture loss, and taken to our Bluffdale, Utah laboratory for further examination, testing, and classification. Information provided on the boring logs attached to this report includes soil descriptions, consistency evaluations, boring depths, sampling intervals, and groundwater conditions. The borings were backfilled with cuttings prior to the drill crew leaving the site.

American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 2

A field log of each boring was prepared by a Terracon field engineer. These logs included visual classifications of the materials encountered during drilling as well as the driller’s interpretation of the subsurface conditions between samples. Final boring logs included with this report represent the engineer's interpretation of the field logs and include modifications based on laboratory observation and tests of the samples.

2.1 Soil Profile

Based on the results of the seven soil borings, subsurface conditions at the Visitor Center site can be generalized as follows:

Timpanogos Cave Visitor Center

Stratum Approximate Depth to

Bottom of Stratum (feet)

Material Description Consistency/ Density

1 4 ½ - 14 ½ (1) Fill – Silty Gravel with Sand (GM) Loose to Medium

Dense

2 26 ½ (2)

Silty Gravel with Sand (GM) with cobbles and possibly boulders, and interbedded layers of Silty Sand with Gravel, and Silty Sand.

Medium Dense to Dense

1. Encountered in borings B-2, B-3, and B-7

2. Maximum depth explored

NPS-USFS/Inter-Agency Complex

Stratum Approximate Depth to

Bottom of Stratum (feet)

Material Description Consistency/ Density

1 1 Silty Clay (CL-ML) with gravel, some cobbles and boulders

2 20 ½ (3) Silty Gravel (GM) with cobbles and possibly boulders, and interbedded layers of Silty Sand with Gravel

Very Dense

3. Maximum depth explored

Conditions encountered at each boring location are indicated on the attached individual boring logs, Exhibits 3 to 11 in Appendix A of this letter. Stratification boundaries on the boring logs represent the approximate location of changes in soil types; in situ, the transition between materials may be gradual.

American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 3

2.2 Groundwater

Groundwater was not encountered within the depths explored at the time of field exploration.

These observations represent groundwater conditions at the time of the field exploration and may not be indicative of other times, or at other locations. Conditions can change with varying seasonal and weather conditions resulting in increased surface infiltration and slope seepage as well as rising groundwater levels in the valley floor alluvium. Site drainage and development changes can also affect groundwater conditions.

LABORATORY TESTING3.0

Samples retrieved during the field exploration were taken to our laboratory for testing and further observation. At that time, the field descriptions were confirmed or modified as necessary and an applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials.

Laboratory tests were performed in general accordance with the applicable ASTM, local or other accepted standards. Selected soil samples were tested for the following engineering properties:

n Direct shear n pH n Atterberg Limits n Minus 200 n In-situ Water Content n Resistivity n Soluble Sulfates n Soluble Chlorides

Results of the laboratory tests are summarized herein and on the attached boring logs and exhibits.

3.1 Test Results

Results from analytical testing are summarized below:

TEST RESULTS

Sample Location

TEST RESULTS

pH Resistivity (ohm-cm)

Sulfate (ppm)

Chloride (ppm)

B-1 @ 5 ft. 9.22 4,060 <5.16 13.0

B-2 @ 10 ft. 9.18 4,440 10.3 10.3

B-3 @ 2.5 ft. 9.89 484 6.73 439

B-3 @ 7.5 & 15 ft. 9.14 405 16.7 71.5

American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 4

Sample Location

TEST RESULTS

pH Resistivity (ohm-cm)

Sulfate (ppm)

Chloride (ppm)

B-4 @ 7.5 ft. 9.79 448 <5.07 563

B-4 @ 12.5 ft. 9.78 577 <5.13 424

B-6 @ 7.5 ft. 9.62 484 21.0 444

B-7 @ 7.5 ft. 8.74 803 13.0 305

B-8 @ 12.5 ft. 8.86 8,450 <5.15 <5.15

B-9 @ 7.5 8.66 7,700 <5.18 <5.18

Based on the test results, sulfate exposure for concrete appears to be low. However, the high chloride contents found for samples from Borings B-3 through B-7 could be corrosive to reinforcing steel.

An aggressive subsurface environment where corrosion can deteriorate buried steel over its design life can generally be identified by soil resistivity, pH, and chloride tests. Resistivity and values vary across the site and range widely between 405 to 4,440 ohm-cm; chloride contents vary similarly between less than 5 and more than 500 ppm. Resistivity values less than 2,000 ohm-cm indicate strongly corrosive conditions for buried metal, while resistivity values over 5,000 ohm-cm indicate little corrosion potential. Chloride concentrations exceeding about 200 ppm are considered deleterious.

Terracon Borings B-1 and B-2 are located in the southerly portion of the site below the slope near the existing Visitors Center and have high resistivity/low chloride values associated with generally low corrosivity. A higher resistivity of over 5,000 ohm-cm was reported by Kleinfelder for a sample also taken from a boring in the south portion of the site in 2013. However, the recent low resistivity – high chloride samples were taken from the 2015 Terracon borings along the edge of UT-92. Based on these results, it appears that such widely divergent results in similar sand-gravel alluvial soils across the site must be due to an external influence, such as roadway salting and the possible effects of snow storage in existing parking areas along the roadway.

These test results are provided to assist in determining the type and degree of corrosion protection that may be required. Although the widely divergent resistivity pattern at the site can be reasonably explained as discussed above, the study has not been comprehensive. The geotechnical recommendations for the rockfall barrier and retaining structure on the southern edge of the site have included moderate corrosion protection precautions for steel elements to be in contact with the ground. This appears to be a prudent approach, but some further consideration/research accompanied by possible testing prior to (and/or during) construction is recommended for the barrier-wall area to solidify the resolution of this matter. It is recommended

American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 5 that in-ground steel elements along the highway be designed for a high-corrosivity environment, and it may be necessary to retain a corrosion engineer to provide additional corrosion protection recommendations.

GEOTECHNICAL DESIGN CONSIDERATIONS AND4.0

RECOMMENDATIONS

4.1 Rockfall Mitigation

The basis for the rockfall mitigation design has been provided in the July 2013 Geotechnical Design Report prepared by the Central Federal Lands Highway Division (CFLHD), Geotechnical Services Branch. In this report, mitigation of the Visitor Center building and parking areas was recommended to consist of a rockfall fence with a height of 10 feet and a minimum energy rating of 500 kJ. The location of the fence was provided in a preliminary plan set accompanying that report.

These design recommendations have been incorporated into the current project planning and design as directed by the NPS. The geotechnical design conducted for the Task Order has involved selection of a rockfall fence/barrier system consistent with the CFLHD report and developing recommendations for system foundations.

In consideration of the marginally stable talus slope above the site and the proposed location of the rockfall barrier, it has been considered expedient and generally less difficult to specify a rigid-post system that does not require upslope anchoring. Based on the current plan configuration of retaining structure and rockfall fence, difficult upslope access is a certainty, and drilling of upslope anchors would potentially necessitate the crane-setting of portable drills for anchor work.

Therefore, the Geobrugg GBE-500A-R (or equal) system with 9.8-foot height rigid posts and 500kJ energy rating has been recommended. With the absence of upslope ropes, rockfall impact on the system does, however, produce significant force and moment reactions that must be resisted by the posts and transferred to the foundation system. Geobrugg provides these reactions for the post base plate per field measurement of prototype systems and recommends that a factor safety of FS = 1.3 be applied for design. Based on this information, the foundation loading applied for design was determined to be approximately as follows:

Vertical Compressive Force: 100,000 pounds Overturning Moment: 120,000 foot-pounds Lateral Force: 38,000 pounds.

Since the foundations are to be located in a talus material that is presumed marginally stable based on its geologic origins, and since the foundation loads are relatively large, a micropile foundation system has been recommended for the rockfall barrier. The possible use of a concrete, American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 6 moment-resisting block foundation was reviewed, and it was determined that insufficient bearing capacity at the edge of the talus slope coupled with the substantial spatial requirements for construction of such a block precluded this option.

A multiple-micropile configuration was selected primarily in consideration of moment resistance requirements and the stabilizing benefits that could be realized using coupled micropiles. The micropile configuration ultimately consisted of one upslope and two downslope piles for each foundation with a separation distance of 4 feet in the direction into the slope. To provide necessary bending and combined stress resistance in the zone immediately below the foundation blocks, a composite micropile section was selected with the upper 10± feet cased (including 1 foot of footing embedment) around a centralized reinforcing bar extending to a depth of 30 feet below the foundation. Due to the potentially open gradation of the talus material, it has been assumed that little grout-ground bond will be available around the casing, and the casing will function primarily to stiffen the micropile section versus bending and shear near the base of the foundation. A presumptive allowable bond stress for the grout-ground bond of 15 psi was assigned for the lower reaches of the talus and the sand-gravel colluvium beneath the talus; this presumptive value is currently believed to provide a bond factor of safety on the expected order of FS=1.5 to

2.0. The bond or geotechnical capacity is to be evaluated by verification/proof testing during the micropile installation. Calculations based on the foregoing design assumptions resulted in a micropile section recommended as follows with calculation documentation provided in Appendix B:

· API N-80 casing, 5.5-inch diameter extending to a minimum permanent depth of 9 feet below foundation base; greater casing depth (either permanent or temporary) may be required for drill hole stability and contract provisions should be made for such payment as warranted.

· No. 11, Grade 75 reinforcing bar centralized within the casing and extending to minimum depth of 30 feet below foundation base. Additional bar length could be required if field observations and testing indicate that a reliable bond length of at least 20 feet below the casing has not been achieved. Contract provisions should be in place for warranted additional payment if geotechnical conditions are responsible.

It is possible to consider alternate micropile sections that may be more compatible with driller equipment and experience with similar site conditions. The contract should allow latitude for alternate design proposals with design engineer review and concurrence required.

Corrosion was considered in the analysis of the foregoing micropile section components by reducing diameter of the casing and bar by nominal amounts of approximately 0.15-inch consistent with FHWA recommendations for moderately aggressive environments. This treatment was considered valid based on the foregoing discussion of resistivity test data. With the corrosion reduced sections, load capacity and moment resistance were checked. Moment resistance was reviewed under combined load-moment conditions using the program AllPile7

American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 7 and found acceptable for the corrosion-reduced section; fixity was determined to occur at approximately 6 feet below the base of the footing.

It is expected that the rockfall barriers will be constructed after construction of the new parking lot retaining wall have been completed. This will facilitate access, presumably from below/adjacent the wall, for drilling via an excavator-mounted drill mast, or to allow setting of drill equipment on-slope. Some difficulty should be anticipated during the installation of the micropiles due to the talus conditions and the uncertain presence of larger size rockfall or colluvial/alluvial inclusions. Due to random openness in the talus slope, the design has assumed that perimeter grouting of the casing will be incomplete, and this axial resistance has been ignored in favor of development with an increased length of grouted reinforcing bar below the casing tip. Advancement of the casing to the full micropile depth, or some depth below the recommended final casing tip elevation, will likely be required for hole stabilization and bar grouting; a grout sock may be also be required for the bar installation.

4.2 Retaining Wall

The new parking lot addition along the south (slope) side of the site is currently expected to require advancement of approximately 20 feet laterally into the hillside behind the existing Visitor Center buildings. This excavation will be made into the talus slope and will result in cut (wall) heights in a general range of 10 to 20 feet. Excavating at the toe of the slope presents stability concerns as the talus is typically considered as a marginally stable slope material. In order to provide both adequate construction safety as toe support is removed and long-term stability for the finished slope/wall above the parking lot, an appropriate retention plan will be required. After consideration of various options such as sheet piling, drilled shafts, and soldier pile-lagging systems, it is believed that a soil nail wall is well-suited for the project needs and environment. A soil nail wall could be installed in a top-down, benched, staged manner to maintain slope stability as the construction occurs progressively. Slope opening will most likely need to be limited along the wall line as the nailing advances in order to manage stability issues; specifications should address such potential sensitivity and require appropriate contractor planning and contingency. The wall will have a shotcrete facing that could be adapted to provide necessary retention for the slope and accommodate decorative facing panels as desired.

The soil nail wall (as would any wall at this location) requires retention of the talus slope at an adequate factor of safety. There is no substantive information available regarding slope composition other than from surficial observation. These observations indicate the slope to have a relatively uniform cover of angular quartzite talus with an estimated 6 to 12-inch average size and an inclination in a maximum range of 30º to 34º. It is assumed that the underlying material consists of variable, poorly-graded colluvium ranging from relatively fine granular materials to varying gradations of talus, plus some larger rockfall inclusions, that have been deposited in a layered fan below the weathering rock wall above the site. It is also assumed that the colluvium ultimately transitions to alluvial sands and gravels near the valley floor elevation as encountered in Boring

American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 8

B-1. Based on this limited information, it has been assumed for stability analysis that the slope material is a layered granular mixture with an overall friction angle of approximately Ø = 32º.

Stability analysis for the nail geotechnical design has been conducted using the soil nail routine in the 2-D, limiting equilibrium computer program (GSTABL7); static and seismic conditions have been analyzed for global/compound stability. For these analyses, factors of safety at FS=1.3 and

1.0 have been considered acceptable for static and seismic cases respectively. For seismic analysis, a pseudo-static approach has been used based on a horizontal seismic coefficient taken as 50% of the peak horizontal ground acceleration (PGA) for a 975-year return event per the USGS Earthquake Hazards Program probabilistic estimate, which indicates a PGA = 0.247g for the site exclusive of any site specific geologic adjustment. Program output has been used to check nail lengths to ascertain adequate development length in resisting zones and acceptable factors of safety per the above criteria at three sections along the wall with retained height varying from 10 to 18 feet. The analysis was based on the following parameters:

· An allowable bond (grout-ground) stress of 15 psi for the slope materials. The character of the talus and other colluvial materials is uncertain and could range to the talus observed at the slope face to possible mixtures ranging from fine-grained to boulder size. It has been assumed that angular, granular materials will dominate for analysis purposes.

· Nails consisting of No. 8, Grade 60 bars with lengths ranging from 10 to 30 feet per the calculations attached. Moderate corrosion allowance has been made per the previous report.

· Nominal nail inclination of 15º below horizontal.

· Nail spacing of 4 feet vertical x 4 feet horizontal in a staggered pattern.

· An allowable nail head load conservatively set at a nominal 15,000 pounds for the shotcrete and concrete panel facing.

The analysis for each of the three slope sections varying from 10 to 18 feet in height considered failure surfaces generated from the toe of the wall upward for a horizontal distance of approximately 100 feet, which is near the trail along the rock cliff face. The failure surfaces were directed to develop on the wall face and through all nails above the toe; the stability of potential failure surfaces passing behind the nail array was also checked. The medium dense to dense sand-gravel encountered during drilling at the Visitor Center site main level was considered as a “firm base” into which failure surfaces would not generate.

The analyses were further subdivided into failure surfaces in the lower and upper halves of the slope to represent internal/compound failures (Case 1) and external/compound failures (Case 2). The allowable nail stresses for the static (AASHTO Service Load Design Group I) and seismic (AASHTO Service Load Design Group VII) were set at 33,333 psi and 43,800 psi respectively for the Fy = 60,000 psi, No. 8 bars recommended. In addition, the bars were reduced for moderate corrosion to a diameter of 0.85 inch. The analysis results are summarized in the following table, and representative stability analysis output is attached for reference.

American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 9

Wall Height (ft)

Station Nail Rows Static FS Case 1

Static FS Case 2

Seismic FS Case 1

Seismic FS Case 2

10 10+72 3 1.68 1.19 1.45 1.00

14 12+75 4 1.82 1.21 1.59 1.03

18 12+90 5 1.75 1.22 1.55 1.03

Case 1: Failure surfaces initiating low on the slope to assess internal and compound stability.

Case 2: Failure surfaces initiating high on the slope to assess compound and external stability.

The controlling failure surfaces extended to the upper reaches of the analysis zone where the static factors of safety dropped to about FS = 1.2 for compound surfaces intersecting only one nail. This safety factor is below the target criterion, but is considered acceptable based on the mitigating analysis conditions of factored allowable stress, corrosion-reduced nail section, and conservative soil strength parameters, i.e. if the friction angle were to be increased by one degree, the factor of safety for the Case 2 static cases would increase to FS = 1.25 despite the nail section reduced for corrosion and allowable nail stresses well below yield. In addition, the controlling surfaces for the upslope failures were relatively shallow with limited nail impact; i.e.

slightly improved from the existing unreinforced, infinite slope condition. The Case 1 factors of safety against failure surfaces generating in the lower half of the slope through the nail array are markedly higher where demand in terms of excavation stability and retention are greatest.

Based on the stability analysis results, the nail design lengths are recommended to range from 10 to 30 feet in bottom to top progression as provided in the following table:

Wall Height (ft)

Station Nail Length (ft)

*Row 1 Row 2 Row 3 Row 4 Row 5 10 10+72 25 20 10 --- --

14 12+75 25 25 20 10 ---

18 12+90 30 25 25 20 10 *Row numbers in descending order top to bottom

Stabilization against shallow upslope failures higher on the slope would require additional nailing in conjunction with a flexible facing such as high-strength steel mesh; it is assumed that such additional improvement is not desired as part of this project.

American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 10

It should be kept in mind that subsurface conditions on the slope are uncertain, and assumptions for the analysis have been made conservatively. This same uncertainty has been incorporated into specifications for nail drilling in the form of conservative requirements/precautions. However, it is possible that unforeseen challenges could still develop in this work. Therefore, it is recommended that geotechnical investigation of the slope by such means as horizontal drilling from the toe area or platform drilling on-slope be undertaken as a means to assess the validity of design assumptions and provide contractor information.

Geotechnical observation of construction is, also, recommended as a further means to confirm design assumptions, or to recommend appropriate adjustments to the design or construction methodology.

SUBSURFACE CONDITION REVIEW – BUILDING SITES5.0

5.1 Visitor Center

Soils at the Visitor Center/Canyon Site were found to consist typically of medium dense to dense silty to poorly-graded sands and gravels as described above in Section 1.1. In the recent subsurface investigation, Boring B-6 is located adjacent the north side of the building footprint per Exhibit 2. This boring logged medium dense to dense sand-gravel soils consistent with the Kleinfelder findings. It should be noted that the recommended foundation preparation called for a 1-foot layer of structural fill over stable native subgrade material. When foundation excavations are made, it is recommended that Kleinfelder review conditions to ascertain that subgrade materials and preparation are in accordance with their design assumptions and recommendations.

5.2 Inter-Agency Center

Borings B-8 and B-9 were performed at the staked locations at the Inter-Agency Site shown on Exhibits 1A and 2A in Appendix A; coordinates of these locations are noted on the Boring Logs attached in Appendix A as Exhibits 10 and 11. Subsurface conditions encountered consisted predominantly of very dense silty gravel with sand, cobbles, and some boulders. These conditions are in substantial accord with those reported by Kleinfelder in their 2011 report. It should be noted that the recommended foundation preparation called for a 10-inch layer of structural fill over stable native subgrade material. When foundation excavations are made, it is recommended that Kleinfelder review conditions to ascertain that subgrade materials and preparation are in accordance with their design assumptions and recommendations.

American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 11

PAVEMENT SECTION UT-926.0

Existing pavement thickness along UT-92 consists of five inches of Hot Mix Asphalt (HMA) over an unspecified thickness of aggregate base. Pavement sections in the parking lot areas consisted of approximately ¼ inch of asphaltic surfacing over native soil or fill in the north lot (Borings B-5 to B-7) to 2 inches of HMA over aggregate base in the south lot (Borings B-1 and B-2). Pavement condition in the north parking lot was very poor to failing with significant deformation, cracking and settlement.

The project is integral with state route UT-92, and project criteria required design per UDOT convention. During initial design, UDOT indicated that a preliminary flexible pavement section would consist of:

4” HMA (Hot Mix Asphalt) 8” UTBC (Untreated Base Course).

However, subsequent UDOT review resulted in a section increase as follows:

6” HMA

6” UTBC

12” GB (Granular Borrow).

This section is therefore recommended for consistency with project design criteria despite the relatively low and seasonal nature of the traffic currently using the highway.

Pavement sections in parking lots should consist of a minimum of 3 inches of HMA over 6 inches of UTBC based on a controlling subgrade profile of silty clay grading to silty sand as encountered below the existing paved areas.

GENERAL COMMENTS7.0

The data presented in this report is based upon the information obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings across the site, or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and appropriate supplemental data can be provided.

American Fork, Utah ■ IDIQ Contract No. P14PC00007 June 17, 2016 ■ Terracon Project No. C4155339

Responsive ■ Resourceful ■ Reliable 12

The scope of services for this project does not include, either specifically or by implication, any environmental or biological assessment of the site or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either expressed or implied, are intended or made. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the information and conclusions contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing.

APPENDIX A

FIELD EXPLORATION

TOPOGRAPHIC MAP IMAGE COURTESY OF

THE U.S. GEOLOGICAL SURVEY

QUADRANGLES INCLUDE: TIMPANOGOS

CAVE, UT (1/1/1998).

SITE LOCATION

Timpanogos Cave National Monument Rockfall Mitigation

SR-92

American Fork, UT

14850 Pony Express Rd, Ste 150N

Bluffdale, UT 84065

61159192

DIAGRAM IS FOR GENERAL LOCATION ONLY,

AND IS NOT INTENDED FOR CONSTRUCTION

PURPOSES

Project Manager:

Drawn by:

Checked by:

Approved by:

CMA

RLC

RLC

RLC

NA

12/16/2015

Project No.

File Name:

Date:

Exhibit

1”=24,000 SF

Scale:

EXPLORATION PLAN

14850 Pony Express Rd, Ste 150N

Bluffdale, UT 84065

61159192

AERIAL PHOTOGRAPHY PROVIDED BY

MICROSOFT BING MAPS

Timpanogos Cave National Monument Rockfall Mitigation

SR-92

American Fork, UT

DIAGRAM IS FOR GENERAL LOCATION ONLY,

AND IS NOT INTENDED FOR CONSTRUCTION

PURPOSES

Project Manager:

Drawn by:

Checked by:

Approved by:

CMA

RLC

RLC

RLC

NA

12/16/2015

Scale:

Project No.

File Name:

Date:

AS SHOWN

Exhibit

TOPOGRAPHIC MAP IMAGE COURTESY OF

THE U.S. GEOLOGICAL SURVEY

QUADRANGLES INCLUDE: LEHI, UT

(1/1/1998) and TIMPANOGOS CAVE, UT

(1/1/1998).

SITE LOCATION

Timpanogos Cave National Monument Rockfall

Mitigation – NPS-USFS Complex SR-92 Highland Hwy

Highland, UT

6949 South High Tech Dr. Ste. 100 Midvale, UT 84047

61159192

DIAGRAM IS FOR GENERAL LOCATION ONLY,

AND IS NOT INTENDED FOR CONSTRUCTION

PURPOSES

Project Manager:

Drawn by:

Checked by:

Approved by:

CMA

RLC

RLC

RLC

NA

2/19/2016

Project No.

File Name:

Date:

1A

Exhibit

1”=2,000’ Scale:

EXPLORATION PLAN

6949 South High Tech Dr. Ste. 100 Midvale, UT 84047

61159192AERIAL PHOTOGRAPHY PROVIDED BY

MICROSOFT BING MAPS

Timpanogos Cave National Monument Rockfall Mitigation – NPS-USFS Complex

SR-92 Highland Hwy Highland, UT

DIAGRAM IS FOR GENERAL LOCATION ONLY,

AND IS NOT INTENDED FOR CONSTRUCTION

PURPOSES

Project Manager:

Drawn by:

Checked by:

Approved by:

CMA

RLC

RLC

RLC

NA

2/19/2016

Scale:

Project No.

File Name:

Date:

AS SHOWN

Exhibit

2A pH, resistivity, sulfate, and chloride analysis completed on soil sample collected at 5' Soil Direct Shear performed on sample collected at 20'

Asphalt, 2 inches thick SILTY SAND WITH GRAVEL (SM), with cobbles, gray, dense to very dense light brown gray

SILTY GRAVEL WITH SAND (GM), with cobbles, brown to gray, medium dense to very dense

Boring Terminated at 21.5 Feet

NP

10 46

10-18-30 N=48

50/5"

20-18-26 N=44

50/5"

7-17-23 N=40

17-24-50/3"

3-5-5 N=10

0.2

14.5

21.5

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

G R

A P

H

IC

L O

G

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

T

G E

O S

M A

R T

L O

G -N

O W

E

LL

C

T

IM

P A

N O

G O

S C

A V

E N

A T

IO

N

A L

M O

N U

M E

N T

R O

C K

F A

LL

M

IT

IG

A T

IO

N

.G P

J T

E R

R A

C O

N

.G

D T

/2

/1

SITE:

Advancement Method:

Odex

Abandonment Method:

Backfilled with soil cuttings upon completion.

6949 S. High Tech Drive Midvale, Utah

Notes:

Project No.: 61159192

Drill Rig: Mobile B-80

Boring Started: 10/16/2015

BORING LOG NO. B-1

A&E Architects PCCLIENT:

Missoula, MT

Driller: Earthcore

Boring Completed: 10/16/2015

Exhibit: No.-3

SR-92

American Fork, Utah

PROJECT: Timpanogos Cave National Monument Rockfall Mitigation

C oh es io n (p sf

P E

R C

E N

T F

IN

E

S

W A

T E

R C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T pc f)

ATTERBERG

LIMITS

LL-PL-PI

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R E

C O

V E

R Y

In

F ric tio n

A ng le

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

Latitude: 40.44367° Longitude: -111.70591°

LOCATION See Exhibit A-2

Groundwater not encountered

WATER LEVEL OBSERVATIONS

sample collected at 10' Soil Direct Shear performed on sample collected at 10'

Asphalt, 2 inches thick FILL - SILTY GRAVEL WITH SAND (GM), brown

SILTY GRAVEL WITH SAND (GM), with cobbles, brown, medium dense brown to gray

SILTY GRAVEL (GM), with cobbles, brown, medium dense to very dense

Boring Terminated at 21.5 Feet

NP

3-2-3 N=5

9-9-9 N=18

10-9-11 N=20

10-10-10 N=20

7-7-6 N=13

11-10-7 N=17

8-19-36 N=55

0.2

4.5

14.5

21.5

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

G R

A P

H

IC

L O

G

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

T

G E

O S

M A

R T

L O

G -N

O W

E

LL

C

T

IM

P A

N O

G O

S C

A V

E N

A T

IO

N

A L

M O

N U

M E

N T

R O

C K

F A

LL

M

IT

IG

A T

IO

N

.G P

J T

E R

R A

C O

N

.G

D T

/2

/1

SITE:

Advancement Method:

Odex

Abandonment Method:

Backfilled with soil cuttings upon completion.

6949 S. High Tech Drive Midvale, Utah

Notes:

Project No.: 61159192

Drill Rig: Mobile B-80

Boring Started: 10/16/2015

BORING LOG NO. B-2

A&E Architects PCCLIENT:

Missoula, MT

Driller: Earthcore

Boring Completed: 10/16/2015

Exhibit: No.-4

SR-92

American Fork, Utah

PROJECT: Timpanogos Cave National Monument Rockfall Mitigation

C oh es io n (p sf

P E

R C

E N

T F

IN

E

S

W A

T E

R C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T pc f)

ATTERBERG

LIMITS

LL-PL-PI

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R E

C O

V E

R Y

In

F ric tio n

A ng le

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

Latitude: 40.44372° Longitude: -111.70519°

LOCATION See Exhibit A-2 sample collected at 7.5' and 15'

Asphalt, 5 inches thick FILL - SILTY GRAVEL WITH SAND (GM), brown grayish-brown, rock in shoe

SILTY GRAVEL WITH SAND (GM), with cobbles, brown to grayish-brown, dense to very dense broken spoon head

Sampler Refusal at 26.25 Feet

1 NP

5-7-8 N=15

2-3-4 N=7

3-3-4 N=7

3-4-7 N=11

5-9-13 N=22

24-20-21 N=41

16-32-19 N=51

5-15-50/3"

0.4

14.5

26.3

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

G R

A P

H

IC

L O

G

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

T

G E

O S

M A

R T

L O

G -N

O W

E

LL

C

T

IM

P A

N O

G O

S C

A V

E N

A T

IO

N

A L

M O

N U

M E

N T

R O

C K

F A

LL

M

IT

IG

A T

IO

N

.G P

J T

E R

R A

C O

N

.G

D T

/2

/1

SITE:

Advancement Method:

Odex

Abandonment Method:

Backfilled with soil cuttings upon completion.

6949 S. High Tech Drive Midvale, Utah

Notes:

Project No.: 61159192

Drill Rig: Mobile B-80

Boring Started: 10/17/2015

BORING LOG NO. B-3

A&E Architects PCCLIENT:

Missoula, MT

Driller: Earthcore

Boring Completed: 10/17/2015

Exhibit: No.-5

SR-92

American Fork, Utah

PROJECT: Timpanogos Cave National Monument Rockfall Mitigation

C oh es io n (p sf

P E

R C

E N

T F

IN

E

S

W A

T E

R C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T pc f)

ATTERBERG

LIMITS

LL-PL-PI

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R E

C O

V E

R Y

In

F ric tio n

A ng le

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

Latitude: 40.44391° Longitude: -111.70615°

LOCATION See Exhibit A-2 sample collected at 12.5'

Asphalt, 5 inches thick SILTY GRAVEL WITH SAND (GM), with cobbles, brown, loose to medium dense gray to brown, dense brown, medium dense light brown, dense brown, medium dense very dense, gravel up to 3" in diameter

Boring Terminated at 26.5 Feet

5-4-3 N=7

3-4-4

15-24-24 N=48

12-11-9

7-16-28 N=44

24-19-39

12-15-2 N=17

0.4

26.5

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

G R

A P

H

IC

L O

G

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

T

G E

O S

M A

R T

L O

G -N

O W

E

LL

C

T

IM

P A

N O

G O

S C

A V

E N

A T

IO

N

A L

M O

N U

M E

N T

R O

C K

F A

LL

M

IT

IG

A T

IO

N

.G P

J T

E R

R A

C O

N

.G

D T

/2

/1

SITE:

Advancement Method:

Odex

Abandonment Method:

Backfilled with soil cuttings upon completion.

6949 S. High Tech Drive Midvale, Utah

Notes:

Project No.: 61159192

Drill Rig: Mobile B-80

Boring Started: 10/17/2015

BORING LOG NO. B-4

A&E Architects PCCLIENT:

Missoula, MT

Driller: Earthcore

Boring Completed: 10/17/2015

Exhibit: No.-6

SR-92

American Fork, Utah

PROJECT: Timpanogos Cave National Monument Rockfall Mitigation

C oh es io n (p sf

P E

R C

E N

T F

IN

E

S

W A

T E

R C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T pc f)

ATTERBERG

LIMITS

LL-PL-PI

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R E

C O

V E

R Y

In

F ric tio n

A ng le

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

Latitude: 40.44393° Longitude: -111.70578°

LOCATION See Exhibit A-2

Asphalt, 1/4 inch thick SILTY GRAVEL WITH SAND (GM), with cobbles, brown

SILTY SAND (SM), dark brown, loose

SILTY GRAVEL WITH SAND (GM), with cobbles, brown to gray, medium dense to very dense

Boring Terminated at 11.5 Feet

5 NP

4-4-3 N=7

50/1"

11-13-8 N=21

11-17-14 N=31

0.0

1.5

4.5

11.5

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

G R

A P

H

IC

L O

G

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

T

G E

O S

M A

R T

L O

G -N

O W

E

LL

C

T

IM

P A

N O

G O

S C

A V

E N

A T

IO

N

A L

M O

N U

M E

N T

R O

C K

F A

LL

M

IT

IG

A T

IO

N

.G P

J T

E R

R A

C O

N

.G

D T

/2

/1

SITE:

Advancement Method:

Odex

Abandonment Method:

Backfilled with soil cuttings upon completion.

6949 S. High Tech Drive Midvale, Utah

Notes:

Project No.: 61159192

Drill Rig: Mobile B-80

Boring Started: 10/17/2015

BORING LOG NO. B-5

A&E Architects PCCLIENT:

Missoula, MT

Driller: Earthcore

Boring Completed: 10/17/2015

Exhibit: No.-7

SR-92

American Fork, Utah

PROJECT: Timpanogos Cave National Monument Rockfall Mitigation

C oh es io n (p sf

P E

R C

E N

T F

IN

E

S

W A

T E

R C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T pc f)

ATTERBERG

LIMITS

LL-PL-PI

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R

E C

O V

E R

Y

In

F ric tio n

A ng le

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

Latitude: 40.44402° Longitude: -111.70521°

LOCATION See Exhibit A-2

Asphalt, 1/4 inch thick SILTY SAND WITH GRAVEL (SM), brown, medium dense to dense

SILTY GRAVEL WITH SAND (GM), with cobbles, brown, very dense

Boring Terminated at 11.5 Feet

NP

8-14-16 N=30

12-15-17 N=32

11-11-14 N=25

21-33-36 N=69

0.0

9.0

11.5

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

G R

A P

H

IC

L O

G

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

T

G E

O S

M A

R T

L O

G -N

O W

E

LL

C

T

IM

P A

N O

G O

S C

A V

E N

A T

IO

N

A L

M O

N U

M E

N T

R O

C K

F A

LL

M

IT

IG

A T

IO

N

.G P

J T

E R

R A

C O

N

.G

D T

/2

/1

SITE:

Advancement Method:

Odex

Abandonment Method:

Backfilled with soil cuttings upon completion.

6949 S. High Tech Drive Midvale, Utah

Notes:

Project No.: 61159192

Drill Rig: Mobile B-80

Boring Started: 10/16/2015

BORING LOG NO. B-6

A&E Architects PCCLIENT:

Missoula, MT

Driller: Earthcore

Boring Completed: 10/16/2015

Exhibit: No.-8

SR-92

American Fork, Utah

PROJECT: Timpanogos Cave National Monument Rockfall Mitigation

C oh es io n (p sf

P E

R C

E N

T F

IN

E

S

W A

T E

R C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T pc f)

ATTERBERG

LIMITS

LL-PL-PI

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R

E C

O V

E R

Y

In

F ric tio n

A ng le

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

Latitude: 40.444° Longitude: -111.70498°

LOCATION See Exhibit A-2 sample collected at 7.5'

Asphalt, 1/4 inch thick FILL - SILTY GRAVEL WITH SAND (GM), brown to dark brown

SILTY SAND (SM), dark brown, loose to medium dense

SILTY GRAVEL (GM), with cobbles, brown, medium dense

Boring Terminated at 11.5 Feet

5-4-3 N=7

5-6-9 N=15

8-5-4 N=9

4-6-7 N=13

0.0

8.5

10.0

11.5

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

G R

A P

H

IC

L O

G

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

T

G E

O S

M A

R T

L O

G -N

O W

E

LL

C

T

IM

P A

N O

G O

S C

A V

E N

A T

IO

N

A L

M O

N U

M E

N T

R O

C K

F A

LL

M

IT

IG

A T

IO

N

.G P

J T

E R

R A

C O

N

.G

D T

/2

/1

SITE:

Advancement Method:

Odex

Abandonment Method:

Backfilled with soil cuttings upon completion.

6949 S. High Tech Drive Midvale, Utah

Notes:

Project No.: 61159192

Drill Rig: Mobile B-80

Boring Started: 10/16/2015

BORING LOG NO. B-7

A&E Architects PCCLIENT:

Missoula, MT

Driller: Earthcore

Boring Completed: 10/16/2015

Exhibit: No.-9

SR-92

American Fork, Utah

PROJECT: Timpanogos Cave National Monument Rockfall Mitigation

C oh es io n (p sf

P E

R C

E N

T F

IN

E

S

W A

T E

R C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T pc f)

ATTERBERG

LIMITS

LL-PL-PI

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R

E C

O V

E R

Y

In

F ric tio n

A ng le

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

Latitude: 40.44402° Longitude: -111.70444°

LOCATION See Exhibit A-2

Direct shear test completed on soil sample collected at 5' sample collected at 12.5'

SILTY CLAY (CL-ML), dark brown, some gravel, cobbles, and boulders SILTY GRAVEL (GM), light brown, very dense, cobbles, possibly boulders oxidation stains fractured rocks trace clay, increasing fines content, oxidation stains brown to gray

Sampler Refusal at 20.6 Feet

NP

16-50/4"

50/5"

49-50/5"

50/5"

13-50/1"

36-42-50/5"

48-50/1"

1.0

20.6

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

G R

A P

H

IC

L O

G

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

T

G E

O S

M A

R T

L O

G -N

O W

E

LL

C

T

IM

P A

N O

G O

S C

A V

E N

A T

IO

N

A L

M O

N U

M E

N T

R O

C K

F A

LL

M

IT

IG

A T

IO

N

.G P

J T

E R

R A

C O

N

.G

D T

/2

/1

SITE:

Advancement Method:

Odex

Abandonment Method:

Backfilled with soil cuttings upon completion.

6949 S. High Tech Drive Midvale, Utah

Notes:

Project No.: 61159192

Drill Rig: Mobile B-80

Boring Started: 12/4/2015

BORING LOG NO. B-8

A&E Architects PCCLIENT:

Missoula, MT

Driller: Earthcore

Boring Completed: 12/4/2015

Exhibit: No.-10

SR-92

American Fork, Utah

PROJECT: Timpanogos Cave National Monument Rockfall Mitigation

C oh es io n (p sf

P E

R C

E N

T F

IN

E

S

W A

T E

R C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T pc f)

ATTERBERG

LIMITS

LL-PL-PI

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R E

C O

V E

R Y

In

F ric tio n

A ng le

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

Latitude: 40.43156° Longitude: -111.7685°

LOCATION See Exhibit A-2

Direct shear test completed on soil sample collected at 5' sample collected at 7.5'

SILTY CLAY (CL-ML), dark brown, some gravel, cobbles and boulders SILTY GRAVEL (GM), brown, very dense

SILTY SAND WITH GRAVEL (SM), light brown, very dense

SILTY GRAVEL (GM), light brown, very dense, fractured rocks, cobbles, possibly boulders

Difficult drilling 17 to 20' fractured rocks, cobbles, possibly boulders

Sampler Refusal at 20.7 Feet

50/5"

50/5"

48-50/2"

50/5"

50/5"

50/3"

34-50/2"

1.0

5.0

6.5

20.7

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

G R

A P

H

IC

L O

G

T H

IS

B

O R

IN

G

L O

G

IS

N O

T V

A

LI

D

IF

S E

P A

R A

T E

D F

R O

M O

R

IG

IN

A

L R

E P

O R

T

G E

O S

M A

R T

L O

G -N

O W

E

LL

C

T

IM

P A

N O

G O

S C

A V

E N

A T

IO

N

A L

M O

N U

M E

N T

R O

C K

F A

LL

M

IT

IG

A T

IO

N

.G P

J T

E R

R A

C O

N

.G

D T

/2

/1

SITE:

Advancement Method:

Odex

Abandonment Method:

Backfilled with soil cuttings upon completion.

6949 S. High Tech Drive Midvale, Utah

Notes:

Project No.: 61159192

Drill Rig: Mobile B-80

Boring Started: 12/4/2015

BORING LOG NO. B-9

A&E Architects PCCLIENT:

Missoula, MT

Driller: Earthcore

Boring Completed: 12/4/2015

Exhibit: No.-11

SR-92

American Fork, Utah

PROJECT: Timpanogos Cave National Monument Rockfall Mitigation

C oh es io n (p sf

P E

R C

E N

T F

IN

E

S

W A

T E

R C

O N

T E

N T

D R

Y U

N

IT

W E

IG

H

T pc f)

ATTERBERG

LIMITS

LL-PL-PI

S A

M P

LE

T

Y P

E

W A

T E

R L

E V

E L

O B

S E

R V

A T

IO

N

S

D E

P T

H

F t.)

R E

C O

V E

R Y

In

F ric tio n

A ng le

F

IE

LD

T

E S

T R

E S

U

LT

S

DEPTH

Latitude: 40.43114° Longitude: -111.76658°

LOCATION See Exhibit A-2

GENERAL NOTES

DRILLING & SAMPLING SYMBOLS:

SSS: Split Spoon - 1-3/8" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger LSS: Split Spoon - 2.42" I.D., 3" O.D., unless otherwise noted PA: Power Auger ST: Thin-Walled Tube – 2.875" O.D., unless otherwise noted HA: Hand Auger RS: Ring Sampler - 2.42" I.D., 3" O.D., unless otherwise noted RB: Rock Bit SK: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary

The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SSS) the last 12 inches of the total 18-inch penetration with a 140-pound hammer falling 30 inches is considered the “Standard Penetration” or “N-value”.

Water levels indicated on the boring logs are the levels measured in the borings at the times indicated.

Groundwater levels at other times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater. In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations.

DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System.

Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size.