FINAL_AZ_FLAP_237(1)_Mormon_Lake_Road_Geotech_Rpt.pdf

MORMON LAKE ROAD

COCONINO COUNTY ROAD 90

COCONINO NATIONAL FOREST, AZ

AZ FLAP 237(1)

FINAL Geotechnical Report

Report No. AZ-CX-237-18-01

Prepared by Federal Highway Administration

Central Federal Lands Highway Division

Geotechnical Services Branch June 2018

SIGNATURE SHEET

Report prepared by: ___________________________________________________________

James M. Arthurs, P.E., Ph.D., Geotechnical Engineer

Report reviewed by: ____________________________________________________________ Marilyn D. Dodson, P.E., Geotechnical Engineer

Approved for distribution by: ____________________________________________________

Khamis Y. Haramy, Lead Geotechnical Engineer

Date: _____________________________________

Distribution

N:\AZ\az237(1)\Geotech\7_FINALDocs K:\TechServices\Geotech\1. Geotech Project Reports Project Management Project Development, Lead Designer

7/12/2018

TABLE OF CONTENTS

SECTION 1-- INTRODUCTION

1.1 SITE CONDITIONS

1.2 PROPOSED CONSTRUCTION

1.3 OBJECTIVE AND SCOPE

SECTION 2-- GEOLOGY AND SEISMICITY

2.1 GEOLOGY

2.2 GEOLOGIC HAZARDS

2.3 SEISMICITY

2.4 SEISMIC DESIGN PARAMETERS

SECTION 3-- FIELD INVESTIGATION

SECTION 4-- RECOMMENDATIONS

4.1 GENERALIZE SUBSURFACE PROFILE

4.2 CUT SLOPE RECOMMENDATIONS

4.3 EMBANKMENT SLOPES

4.4 CORROSION

4.5 SHRINK/SWELL RECOMENDATIONS

4.6 ROCK SLOPE ASSESSMENT

4.7 POTENTIAL BORROW SOURCES

4.8 LIMITATIONS

SECTION 5-- REFERENCES

TABLES

TABLE 1: NEARBY SEISMIC HAZARD FAULTS

TABLE 2: NEARBY INACTIVE FAULTS

TABLE 3: RECOMMENDED CUT SLOPE RATIOS BY STATION

TABLE 4: RESULTS OF KINEMATIC ANALYSIS

TABLE 6: POTENTIAL BORROW AREAS

FIGURES

FIGURE 1: ROCKFALL CATCHMENT DITCH

FIGURE 2: BASALT OUTCROP NEAR STA. 242+00

FIGURE 3: BASALT OUTCROP NEAR STA. 263+50

FIGURE 4: BASALT OUTCROP AND SOIL NEAR STA. 294+00

FIGURE 5: SOIL CUT SLOPE NEAR STA. 370+00

FIGURE 6: SOIL CUT SLOPE NEAR STA. 386+00

FIGURE 7: DACITE OUTCROP NEAR STA. 389+50

FIGURE 8: SOIL SLOPE NEAR STA. 392+50

APPENDICES

APPENDIX A: PROJECT LOCATION AND GEOLOGIC MAPS

APPENDIX B: CUT SLOPE LOG AND PHOTOGRAPHS

APPENDIX C: ROCK SLOPE KINEMATIC ANALYSIS

SECTION 1--INTRODUCTION

This report presents the results of the geotechnical engineering investigation conducted for the Mormon Lake Road, AZ FLAP 237 (1). The project is located southeast of Flagstaff, AZ along the low volume Mormon Lake Road and provides access to residential homes from the Lake Mary Road (Appendix A, Figure A-1). The route also provides access to Mormon Lake and the recreational lands of the Coconino National Forest. Due to the roadway’s high elevation setting and rolling terrain, the site is a popular recreation area for bicyclists and runners, with several organized bicycling events held each year.

The project begins at the southern intersection of Mormon Lake Road and Lake Mary Road and proceeds northward in a semi-circular route around Mormon Lake before terminating at the northern intersection with Lake Mary Road.

1.1 SITE CONDITIONS

Mormon Lake Road is currently a paved, two-lane road with 12-foot lanes and 0- to 2-foot wide paved shoulders. The current average daily traffic (ADT) on the route is 758 with posted speed limits between 15 and 45 miles per hour. Cut slopes along the route are composed of volcanic rock and associated colluvial and residual soils and generally less than 10-feet high. The road is bordered by single-family residential and commercial development, agricultural land, and undeveloped areas of the Coconino National Forest. Vegetation includes grasses and herbs, scrub and bushes, and coniferous trees.

1.2 PROPOSED CONSTRUCTION

The proposed project consists of pulverizing the existing asphalt section for the entire project length. Outside of the unincorporated residential areas of Mormon Lake, the road will be widened to include 5-foot wide paved shoulders. In these locations, additional aggregate base will be added to the road section to provide for the wider section and minor correction to super-elevation of the roadway. The proposed roadway section includes a 4-foot wide roadside ditch with a 1 (vertical) to 4 (horizontal) side slope along the inboard shoulder. As part of this widening, cuts and fills extending up to 20 feet are planned. The project also includes paving, drainage structure improvements, and shoulder and ditch reconditioning.

Cut and fill slopes are anticipated between Stations 100+00 and 170+00 and between Stations 210+00 and 613+09. The remainder of the project is anticipated to follow the existing roadway footprint. Project stationing in this report is based on interim plans dated May 24, 2018 and may differ from the final project stationing.

1.3 OBJECTIVE AND SCOPE

The objectives of this study are specifically to conduct engineering analysis and develop recommendations concerning cut slopes and excavations. In accomplishing these objectives, the scope of work included visual site reconnaissance, correlation of available data, stability analysis, and recommendations. This report present recommendations predominantly based on a limited site reconnaissance conducted during the preliminary plan review site visit and a later surface mapping site visit.

SECTION 2--GEOLOGY AND SEISMICITY

2.1 GEOLOGY

2.1.1 Regional Geology

Mormon Lake Road is southeast of Flagstaff, Arizona, and is located within the Mogollon Slope of the Colorado Plateau Province. The roadway is underlain by Quaternary alluvial deposits and Tertiary volcanic bedrock.

Quaternary alluvium is described as unconsolidated clay, silt, sand, and gravel, chiefly of local derivation, on modern flood plains and terraces as much as 80-feet above flood plains (Weir et al., 1986; Weir and Nealey, 1993; Weir et al., 1994). This material can locally include small colluvial, eolian, and fan deposits. Volcanic rocks in the project area are typically medium gray to dark gray basalt with dacite and andesite mapped near Dairy Springs campground. The Kaibab Formation underlies the volcanic units and consists of silty to sandy dolomite, limestone, and fine-grained sandstone.

The project site is located near the Mormon Mountain Anticline, a broad regional structure whose east flank is characterized by low northeasterly dips. Other details of structure within the area are generally obscured by relief on unconformities, by solution of carbonate beds, and by the mantle of volcanic rocks.

2.1.2 Site Geology

The site topography is characterized by gently rolling or undulating surface underlain by bedrock. The bedrock exposed in the area includes basalt and dacite and is strong to very strong with considerable variations in weathering. The bedrock is typically overlain by thin deposits of alluvial, colluvial, and residual soils. The overburden soils include both granular deposits of silty sand and gravel, and finer grained deposits of silty to sandy clay. The clay is a common weathering product of the basalt and is typically moderate to high in plasticity. A geologic map of the project area is presented in Figure A-2 in Appendix A.

2.2 GEOLOGIC HAZARDS

Geologic hazards exist from both the natural environment of the project sites and from existing and proposed construction of the roadway. Existing steep slopes composed of highly fractured dacite pose a rockfall hazard. High plasticity clay, formed from weathering of basalt, commonly exist on top of the basalt bedrock combined with identified zones of poor-drainage may reduce the subgrade load bearing capacity and should be carefully considered during project planning and construction.

2.3 SEISMICITY

The potential of earthquake damage from ground movement is relatively low to moderate at the project site. The nearest seismic source fault to the project area is the is the Big Chino – Little Chino fault, located approximately 53 miles from the center of the project. Other seismic source faults are more distant and summarize in Table 1. Numerous non-seismic fault zones are also located near the project and are summarized in Table 2.

2.4 SEISMIC DESIGN PARAMETERS

No structures requiring seismic design parameters are currently proposed for inclusion in the Mormon Lake Road project.

Table 1: Nearby Seismic Hazard Faults

FAULT OR FAULT ZONE

DISTANCE

FROM CENTER

OF PROJECT

FAULT

PARALLEL

SLIP RATE

FAULT

LENGTH AGE

(miles) (inch/year) (miles) (years)

Big Chino Little Chino Fault Zone 53.6 0.0043 40.4 <15,000

Aubrey Fault Zone 88.1 0.0008 40.4 <130,000

Table 2: Nearby Inactive Faults

FAULT OR FAULT ZONE

DISTANCE

FROM

CENTER

OF

PROJECT

FAULT

PARALLEL

SLIP RATE

FAULT

LENGTH AGE

(miles) (inch/year) (miles) (years)

Mormon Lake Fault Zone 2.48 <0.01 9 <1,600,000

Lake Mary Fault Zone 4.48 <0.01 16 <15,000

Casner Cabin Fault Zone 17.78 <0.01 6 <130,000

Oak Creek North Fault Zone 20.3 <0.01 4 <1,600,000

Phone Booth Faults 20.36 <0.01 4 <750,000

Rock House Fault 23.8 <0.01 4 <1,600,000

Metz Tank Fault 24.21 <0.01 4 <130,000

Bellemont Fault 26.52 <0.01 7 <1,600,000

FAULT OR FAULT ZONE

DISTANCE

FROM

CENTER

OF

PROJECT

FAULT

PARALLEL

SLIP RATE

FAULT

LENGTH AGE

(miles) (inch/year) (miles) (years)

Garland Prairie Faults 30.7 <0.01 3 <130,000

Sinagua Faults 31.55 <0.01 3 <1,600,000 Black Point/Doney Mountain

Fault Zone 36.15 <0.01 15 <15,000

Deadman Wash Faults 37.01 <0.01 1 <15,000

Bill Williams Fault 38.21 <0.01 13 <130,000

Maverick Butte Faults 38.76 <0.01 2 <130,000

Arrowhead Fault Zone 38.99 <0.01 3 <130,000

SECTION 3--FIELD INVESTIGATION

A preliminary visual reconnaissance program within the proposed project limits was conducted by Central Federal Lands Highway Division (CFL) Geotechnical personnel on November 6 through 8, 2017. The reconnaissance program primarily focused on the following:

• Characterizing geologic materials in existing and proposed cut slopes,

• Identifying locations where excavation may be complicated due to hard rock, and

• Identifying geological and geotechnical hazards.

The scope of the reconnaissance was limited to general identification and characterization of various materials that will be encountered during the project planning and construction.

Supplemental information was collected on May 31 – June 1, 2018, which included the following:

• Existing native and cut slope angles, and ditch widths,

• Further characterization of geologic materials,

• Excavation conditions and ripability of materials,

• Discontinuity orientations in bedrock located between Sta. 388+00 and Sta. 390+50, and

• Identification of potential borrow areas.

Logs and photographs of the existing cut slopes are included in Appendix B.

A subsurface exploration program was not performed as there are no proposed structures nor significant cuts or fills planned as part of the project. However, subsurface data was obtained as part of CFL pavements investigations and are summarized in the project Pavement and Materials Report dated December, 2017.

The pavement investigation determined that the pavement section consists of hot mix asphalt pavement placed on approximately 2-inches of asphalt treated base and 8- to 20-inches of red sandy gravel subgrade interpreted as cinder materials of scoriaceous basalt sourced from nearby borrow areas. The pavements investigation included six Dynamic Cone Penetration (DCP) tests.

Five of the DCP tests encountered soft, clayey materials below the pavement section, while one encountered refusal (potential rock) at approximately 22 inches below grade.

SECTION 4--RECOMMENDATIONS

This section presents analyses and recommendations pertaining to cut and fill slope ratios and underdrains. It also provides generalized subsurface profiles based on the field reconnaissance and pavement boring data.

4.1 GENERALIZE SUBSURFACE PROFILE

Soil deposits encountered in the existing cut slopes along the proposed roadway alignment were mostly of colluvial or residual origin, and are characterized for design purposes as silty sand and sandy clay. These slope materials are generally formed by in situ weathering and erosion of basaltic and dacitic volcanic rocks. These materials typically have low to moderate friction angles and moderate to high cohesion, indicating low to moderate quality for roadway construction. Isolated areas of bedrock outcrop were observed throughout the alignment, with large outcrops located between Station 375+00 and Station 410+00. Bedrock at this location is classified as dacite and is generally strong to very strong, with closely spaced, steeply dipping to near vertical fractures. The fractures generally have narrow apertures. Bedrock throughout the rest of the project is composed of basalt with moderately to widely spaced fractures. Bedrock outcrops are typically lightly to moderately weathered.

4.2 CUT SLOPE RECOMMENDATIONS

In general, the maximum recommended slope ratios for proposed cut slopes is 1V:1.5H for the cut slopes constructed in residual and colluvial soils. The recommended slope ratio is dependent on the nature of the observed material and the existing stability of the slope. During the excavation of cut slopes on the project boulders up to 5 feet (or larger) should be expected within the proposed excavation limits. Care should be taken to avoid over excavation by removing (or destabilizing) boulders found to be crossing the proposed finished slope “neat line”. Based on the proposed limits of cut slopes, conventional excavation methods will generally be suitable.

Limited blasting of isolated boulders may be cost effective, but is restricted to specific times and locations due to sensitive species in the project area. Blasting is assumed to be required for cuts in intact dacite materials. Use of blasting must conform to the requirements of the environmental permitting documents.

A station-by-station recommended cut slope ratio is presented in Table 3. These recommendations are based off of the preliminary design alignment. Seepage was not noted during field exploration as described previously. If seepage is encountered during construction, the cut slope angle should be reduced to maintain a stable slope. For all soil slopes less than 5 feet high, a cut slope ratio of 1:2 (V:H) should be used.

Table 3: Recommended Cut Slope Ratios by Station

STA. TO STA. SIDE

EXISTING

CUT

SLOPE

HEIGHT

(FT)

SLOPE TYPE

MAXIMUM

RECM. CUT

SLOPE

RATIO (V:H)

MAXIMUM

RECM. CUT

SLOPE

HEIGHT

(FT)

100+00 - 210+00 No cut slopes proposed.

210+00 - 375+00 LT &

RT 10 - 15

Silty SAND to sandy CLAY with minor basaltic bedrock

1:1.5 20

375+00 - 410+00 LT 5 – 45

Silty SAND to sandy CLAY with minor dacite bedrock

1:1.5 30

375+00 - 410+00 LT 5 -20 Dacite bedrock 1:0.5 50

410+00 - 613+34 LT &

RT 5 - 15

Silty SAND to sandy CLAY with minor basaltic bedrock

1:1.5 20

4.3 EMBANKMENT SLOPES

Embankments up to 15 feet high are proposed for the project. A slope ratio of 1V:2H is recommended as the maximum slope ratio for proposed fill slopes. Construct embankments in accordance with Section 204 of the FP-14 and the project Special Contract Requirements.

Specifically, handle boulders and cobbles in accordance with Subsection 204.10. Boulders up to 4-foot diameter (average 1-foot to 3-foot) were observed on the surface and can be anticipated during construction.

4.4 CORROSION

Corrosion tests were conducted as part of the Pavements and Materials investigation for the design of buried metal culverts. Refer to the Pavements and Materials Report dated December 2017 detailing the recommendations for corrosion mitigation and supporting laboratory testing.

4.5 SHRINK/SWELL RECOMENDATIONS

The proposed Mormon Lake Road will require cuts in slopes comprised of sand and clay with local bedrock outcrops. Existing fill slopes appear to be composed of loose sandy clay materials.

For the purpose of estimating shrink/swell values, silty sand and sandy clay are assumed to be the predominate material located in permanent cuts. The recommended shrink/swell factors are based on a combination of standard tabled values for common materials in the FLH Technical Guidance Manual (2006) and experience with other CFLHD projects in similar materials.

The estimated shrink/swell values for the silty sand and sandy clay of the cut slopes are assumed to Shrink 10 percent (Shrink Factor 0.90) if reused as embankment. The estimated shrink/swell values for the basalt and dacite bedrock of the cut slopes are assumed to Bulk 15 percent (Bulk Factor 1.15) if reused as embankment or subbase materials.

4.6 ROCK SLOPE ASSESSMENT

The rock slopes along the alignment are generally performing satisfactorily. These rock slopes are primarily located between Stations 375+00 and 410+00 and are primarily composed of dacite. Locally, the rock is highly fractured with some adversely oriented fractures, resulting in a moderate potential for rockfall to occur. Potential for rockfall is assumed to exist for new cut slopes constructed in dacite materials between Stations 375+00 and 410+00. Based on observations of the existing slopes and roadside ditches, both block and total volume of rockfalls are likely to be small. Therefore, an appropriately sized rockfall catchment ditch is likely to retain the majority of debris from rockfall from existing or proposed rock slopes.

4.6.1 Rock Slope Kinematic Analysis

Fracture orientation data was collected at the existing rock cut slope located between Station 388+00 and Station 390+50 (Figure B-10). The Dips 7.0 software published by RocScience was used to collect, display, and analyze the fracture orientation data. Dips 7.0 is a software package that produces stereonet plots of fracture orientations and can be used to conduct kinematic analysis of rock slopes based on a proposed cut slope orientation and rock friction angle.

Kinematic analysis included three potential failure modes: sliding, wedge, and toppling. Sliding failure occurs where a fracture plane dips out of the cut slope, while a wedge failure occurs when the intersection of two fractures planes dips out of the cut slope. For these failures to occur, the dip angle must be steep enough to overcome frictional resistance along the fracture(s). Toppling failure occurs when fractures dip steeply into the cut slope, creating a potential for tensile failure of the rock mass. All three failure modes are dependent on the relative geometries of the rock fractures and cut slope, as well as rock mass properties such as unit weight and friction angle.

Analysis was performed using the collected fracture data, a proposed cut slope orientation of N25°E, and a friction angle of 45° assumed based on published values for similar rock types with similar fracture conditions. Fractures in the dacite bedrock are typically closely spaced, relatively smooth, and wavy.

Due to the limited rock exposure and fracture data collected, strong statistical fracture sets were not identified. Fracture orientation throughout the rock mass may differ from the data collected in the field. Based on this analysis and our observations of the existing cut slope, a maximum slope angle of 1V:0.5H (approximately 64 degrees) is recommended for cut slopes constructed in the dacite bedrock. The kinematic analysis indicates low to moderate potential for planar and wedge sliding, and very low probability of toppling failure (Table 4). In addition, the existing slopes cut at a similar angle are performing well, with scattered, small (< 6-inch diameter blocks) evident in the roadside ditch. At this angle, minor rockfall may occur on the cut slope. Therefore, an engineered rock catchment ditch should be included in the cut area. Recommendations for this catchment ditch are presented in Section 4.6.2, below. Results of the rock slope kinematic analysis are included in Appendix C.

Table 4: Results of Kinematic Analysis

FRACTURE

SET FAILURE MODE

CRITICAL

FRACTURES

All Planar Sliding 18.2

Set 1 Planar Sliding 50.0 All Wedge Sliding 41.7 All Flexural Toppling 0 All Direct Toppling 0 All Oblique Toppling 0 All Base Plane 9.1

Set 2 Base Plane 25.0

4.6.2 Rockfall Catchment Analysis

The rockfall catchment area is defined as the area between the roadway edge and the base of the cut slope used to restrict a high percentage of rockfall from reaching the roadway (Figure 1). The use of catchment areas to contain and restrict rockfall from reaching the roadway is one of the best and most cost effective rockfall protective measures. Numerous factors affect the proportion of rockfall retained in a catchment ditch, including slope height, slope angle, relative smoothness of slope and launching features, ditch width, ditch slope, slope material properties, and rockfall block shape and size.

The existing ditches with widths of approximately 10 to 11 feet and approximate 1(V):6(H) to flat foreslopes, appear to retain most of the rockfall that occurs in this section of roadway. No rock was visible on the roadway during the site visits and Coconino County did not note that rockfall debris cleanup was a significant maintenance issue.

Figure 1: Rockfall Catchment Ditch

Due to the relatively low height and low risk of the proposed rock cuts (less than 40 feet), a simple, empirical analysis was used to size the rockfall catchment ditches. The Oregon Department of Transportation (ODOT) Rockfall Catchment Area Design (RCAD) design charts were used to evaluate 1(V):0.5(H) slopes with various slope heights to determine the minimum ditch width for 80 percent rockfall containment (Pierson et al., 2001). This level of catchment is typically acceptable for low volume roads such as the Mormon Lake Road. In addition, based on fracture spacing observed in the rock mass, rockfall consisting of large blocks or large volume events is unlikely. Therefore, 80 percent catchment was selected as the target catchment based on the rock mass conditions and anticipated road use.

As previously stated, the ODOT RCAD design charts are limited to slopes between 40- to 80-feet high. Based on the in progress cross sections prepared for this project, rock slopes are not expected to exceed 30 feet in height. Therefore, the ODOT RCAD charts were extrapolated to provide recommendations for shorter slopes. As previously discussed, numerous factors influence the actual rockfall retention of a catchment ditch. For the analysis and recommendations presented in this section, the rock slope angle and catchment ditch angle were kept constant at 1(V):0.5(H) and 1(V):4(H), respectively. Therefore, we recommend that a minimum 8-foot wide ditch with a 1(V):4(H) foreslope be provided for rock slopes up to 30-feet high cut at a slope ratio of 1(V):0.5(H). If the Contractor elects to expand cut areas to produce borrow material, the slope heights may be increased beyond the analysis and recommendations provided in this report. In this case, the catchment ditches will need to be widened to provide a similar level of safety, and the Geotechnical Engineer should be consulted to provide revised recommendations based on the proposed cut slopes.

4.7 POTENTIAL BORROW SOURCES

Potential exists to expand some cut slopes in the project to produce granular fill materials. With on-site processing and crushing, these materials may be used as sub-base. Materials generated on site should conform to meet the requirements shown in Section 703.05 of FP-14 and the Special Contract Requirements (SCR). If the Contractor elects to expand cut areas to produce fill materials, the maximum slope angles recommended in this report should be followed. Areas identified during the field reconnaissance as potential borrow areas are summarized in Table 5.

Photos from the potential borrow areas are presented in Figure 2 through Figure 8.

Table 5: Potential Borrow Areas

STATION RANGE NOTES

239+00 – 246+00 BASALT outcrop with discontinuities spaced at 1 to 4 feet, with wide aperture and soil infilling.

260+50 – 268+50 BASALT outcrop with discontinuities spaced between

6 inches and 5 feet. Discontinuities generally have wide apertures with soil infilling.

292+50 – 296+00 BASALT outcrop with discontinuities spaced at 1 to 4 feet, with wide aperture and soil infilling.

369+00 – 376+50 Soil (silty SAND) with DACITE blocks up to about 5-foot diameter.

379+50 – 388+00 Soil (silty SAND) with DACITE blocks up to about 3-to 4-foot diameter.

388+00 – 390+50 DACITE, very closely spaced fractures with generally narrow aperture.

390+50 – 397+00 Soil (silty SAND) with DACITE blocks up to about 2-to 3-foot diameter.

Ripability analysis was not performed as part of this scope of work. Based on limited field reconnaissance of the existing cut slopes, the following general recommendations are provided:

1. The basalt bedrock is generally fractured into 1-foot to 4-foot blocks. The fractures frequently have relatively large apertures (openings). Therefore, relatively shallow excavations into the basalt materials are likely possible using conventional, heavy-duty construction equipment in good working order.

2. The dacite bedrock is generally fractured into 6-inch to 12-inch blocks. Fractures typically have very small apertures (openings). Therefore, excavations into the dacite materials are likely to require blasting.

Figure 2: Basalt outcrop near Sta. 242+00.

Figure 3: Basalt outcrop near Sta. 263+50. Existing cut is 10- to 12-feet high.

Figure 4: Basalt outcrop and soil near Sta. 294+00. Existing cut is less than 10-feet high.

Figure 5: Soil cut slope near Sta. 370+00. Soil is silty sand with blocks of dacite up to 4-feet in diameter. Existing cut is approximately 15-feet high.

Figure 6: Soil cut slope near Sta. 386+00. Soil is similar to Figure 5, above. Existing cut slope is approximately 20-feet high.

Figure 7: Dacite outcrop near Sta. 389+50. Existing cut slope is approximately 45 feet high at 1(V):0.5(H).

Figure 8: Soil slope near Sta. 392+50. Existing cut slope is approximately 10-feet high.

4.8 LIMITATIONS

The recommendations in this report are based on the data obtained from visual investigations, field review, and laboratory test results. The results of these explorations and tests represent conditions at the specific locations indicated. Subsurface variations across the site are likely and may not become evident until excavation is performed. The Analysis and Recommendations sections in this report include interpretations and recommendations developed by the Government in the process of preparing the design. These interpretations are not intended as a substitute for the personal investigation, independent interpretation, and judgment of the Contractor.

SECTION 5--REFERENCES

American Association of State Highway and Transportation Officials (AASHTO), 2015, LRFD Bridge Design Specifications, 7th Edition with 2015 interim revisions.

California Department of Transportation (CalTrans), 2017, Caltrans ARS Online (v2.3.09).

http://dap3.dot.ca.gov/ARS_Online/

Federal Lands Highway (FLH), Project Development and Design Manual (PDDM), FHWA, 2008, dated March.

Federal Lands Highways (FLH), 2006, Technical Guidance Manual (TGM), A geotechnical supplement to the FLH Project Development and Design Manual.

Pierson, L.A., Gullixson, C.F., and Chassie, R.G. 2001. “Rockfall Catchment Area Design Guide, Final Report.” Oregon Department of Transportation, Report No. SPR-3(032).

Salem, OR.

United States Geological Survey (USGS) 2008 National Seismic Hazard Maps http://geohazards.usgs.gov/cfusion/hazfaults_search/hf_search_main.cfm

Weir, G.W., Ulrich, G.E., and Nealey, L.D., 1986, “Geologic Map of the Sedona 30’ X 60’ Quadrangle, Yavapai and Coconino Counties, Arizona” U.S. Geological Survey, Miscellaneous Investigations Series Map I-1896, scale 1:100,000.

Weir, G.W. and Nealey, L.D., 1993, “Geologic Map of the Turkey Mountain Quadrangle, Coconino County, Arizona” U.S. Geologic Survey Miscellaneous Field Studies Map MF- 2230, scale 1:24,000.

Weir, G.W., Ulrich, G.E., and Nealey, L.D., 1994, “Geologic Map of the Long Valley Quadrangle, Coconino County, Arizona” U.S. Geological Survey, Geologic Quadrangle Map GQ-1735, scale 1:24,000.

APPENDIX A

PROJECT LOCATION

AND GEOLOGIC MAPS

APPENDIX B

CUT SLOPE LOG

AND PHOTOGRAPHS

Cut Slope Field Log

Begin Sta.

End Sta.

Offset

(LT/RT)

Existing Conditions

Description (Lithology) {1- Basalt, 2- Basalt Residual, 3- Dacite, 4- Dacite Residual}

Native Slope Angle

Exist.

Cut

Slope Angle

Exist.

Cut

Slope Height

Exist.

Ditch Width

Soil / Rock Type No.

(deg) (deg) (ft) (ft)

239+00 246+00 LT 0 - 16 22.5 -

NV < 10 10 -

12 1/2

BASALT, redish brown and gray, scoriaceous, very fine grained to medium grained (porphyritic), fresh to slightly weathered, strong to very strong.

Discontinuities are moderately to widely spaced (1' - 4'), poor to very poor condition (rough, wide appeture, soil filled). Two sets of fractures, one subhorizontal and one sub-vertical. Fracture fill is composed of residual/colluvial soil.

clayey SAND with gravel, cobble, and boulder, Dry, Low-Medium plastic, brown, moderately vegetated.

260+50 268+50 LT 0 26 - NV 10 - 12 10-12 1/2

Basalt- see above, Blocks upt to 25' Dia. Locally joint space <6", Porphyritic sample collected.

Clayey sand - see above

273+00 276+50 LT 0 - 10 23 - 80 < 10 16 1/2 Mainly soil (>70%), clayey sand, as above. Isolated basalt rock outcrops, concentrated in middle of cut

292+50 296+00 RT 0 26 - NV < 10 14 1/2 Mostly basalt rock. Soil (clayey sand) from 292+35 - 293+00

306+00 309+00 RT 0 18 < 5 14 1/2 Mostly soil (clayey sand), little intact rock, isolated blocks up to 3' DIA

366+50 378+00 LT 10 - 23 26 15 10 4

Silty SAND with gravel, cobble, and boulder, orange, gray,and pink, dry. Non-plastic. Boulders up to 4' dia. Boulders are composed of DACITE, stained to moderately weathered, medium strong to very strong rock. Existing ditch effective against rockfall.

Sta.

End Sta.

Offset

(LT/RT)

Existing Conditions

Description (Lithology) {1- Basalt, 2- Basalt Residual, 3- Dacite, 4- Dacite Residual}

Native Slope Angle

Exist.

Cut

Slope Angle

Exist.

Cut

Slope Height

Exist.

Ditch Width

Soil / Rock Type No.

(deg) (deg) (ft) (ft)

378+00 380+00 LT 23 33 20 10 3/4

Silty SAND as above, non-vegetated, likely at max safe angle. Intact rock outcrop above cut slope.

DACITE-orange, gray, and pink, very fine to medium grained (porphyritic), fresh to slightly weathered, strong to very strong. Discontinuities are sub-horizontal, extremely to very closely spaced, good to excellent condition (close appeture, rough and wavy) or sub-vertical, widely spaced, very poor to poor condition (wide appeture, no infiller).

380+00 383+00 LT 70 - 80

(rock) 33 5 - 10 10 3/4 Sitly SAND and DACITE as above. Minimal existing cut slope, DACITE outcrop behind the cut slope

383+00 386+00 LT 15 26 5 - 10 10 3/4 Silty SAND and DACITE, as above

386+00 388+00 LT 15 35 20 10 3/4 Silty SAND and DACITE, as above

388+00 390+50 LT 45 60 45 11 3

DACITE, similar to above, pink, orange and dark gray mottled. Discontinuities, very closely spaced to moderately widely spaced, Rough undulating to smooth planar. Discontinuity orientation data collected. Hand sample collected @ STA

389+00 RT

390+50 392+00 LT 45 35 15 11 3/4 Sitly SAND and DACITE as above. Up to 4' boulders. Rock outcrop behind cut slopes.

392+00 396+50 LT 15 - 20 35 < 10 11 3/4 Silty SAND and DACITE, as above. Very little rock. Mainly soil (approximately 80%). Some 3' - 4' boulders from STA 395+00 - 396+00

396+50 401+00 LT 26 45 16 12 4

Silty SAND and DACITE, as above. Soil slope ravelling. Includes bedrock outcrop at STA 398+00 - 400+00. Wide bench between cut slope and rock outcrop. Ditch nearly full of soil.

402+50 403+00 LT 52 90 < 10 0 3 Silty SAND and DACITE, as above. Tall rock cliffs located close behind existing cut slope

Sta.

End Sta.

Offset

(LT/RT)

Existing Conditions

Description (Lithology) {1- Basalt, 2- Basalt Residual, 3- Dacite, 4- Dacite Residual}

Native Slope Angle

Exist.

Cut

Slope Angle

Exist.

Cut

Slope Height

Exist.

Ditch Width

Soil / Rock Type No.

(deg) (deg) (ft) (ft)

404+00 405+50 LT 66 45 < 10 12 3/4 Silty SAND and DACITE, as above. Tall rock cliffs located close behind existing cut slope

405+50 410+00 LT 20 30 15' 11 4 Silty SAND and DACITE, as above. Plentiful 1 - 3' boulders at surface. Thick tree coverage.

456+00 463+00 RT 0 18 < 5 12 1/2 Clayey SAND with gravel, cobble and boulders, similar to other Type 2 deposits.

Boulders up to 24", Intact rock near 460+00, potential source, limited length of cut

580+00 586+00 LT 6 - - 7 2 Clayey SAND with gravel, as above. Minor cut area. Up to 3' boulders on surface

580+00 586+00 RT 6 - - 9 2 Clayey SAND with gravel, as above. Minor cut area. Up to 3' boulders on surface

586+00 588+00 RT 6 16 < 5 8 2 Clayey SAND, as above. Few 12" boulders

NV = Near Vertical

Figure B-1: Proposed cut slopes between Sta. 239+00 and Sta. 246+00.

Figure B-2: Proposed cut slopes between Sta. 260+50 and Sta. 265+00.

Figure B-3: Proposed cut slopes between Sta. 265+00 and Sta. 268+50.

Figure B-4: Proposed cut slopes between Sta. 273+00 and Sta. 276+50.

Figure B- 5: Proposed cut slopes between Sta. 292+50 and 296+00.

Figure B-6: Proposed cut slopes between Sta. 292+50 and Sta. 296+00.

Figure B-7: Proposed cut slopes between Sta. 366+00 and Sta. 376+00.

Figure B-8: Proposed cut slopes between Sta. 376+00 and 382+00.

Figure B-9: Proposed cut slopes between Sta. 382+00 and Sta. 388+00.

Figure B-10: Proposed cut slopes between Sta. 388+00 and Sta. 390+50.

Figure B-11: Proposed cut slopes between Sta. 390+50 and Sta. 410+00.

Figure B-12: Proposed cut slopes between Sta. 456+00 and Sta. 463+00.

Figure B-13: Proposed cut slopes between Sta. 580+00 and 586+00 (left) and 586+00 and 588+00 (right).

APPENDIX C

ROCK SLOPE

KINEMATIC ANALYSIS

N

S

EW

1m

1m

2m

2m

3m

3m

Symbol Feature

Pole Vectors

Color Density Concentrations

0.00 - 1.90

1.90 - 3.80

3.80 - 5.70

5.70 - 7.60

7.60 - 9.50

9.50 - 11.40

11.40 - 13.30

13.30 - 15.20

15.20 - 17.10

17.10 - 19.00

Contour Data Pole Vectors

Maximum Density 18.18%

Contour Distribution Schmidt

Counting Circle Size 1.0%

Kinematic Analysis Planar Sliding

Slope Dip 64

Slope Dip Direction 115

Friction Angle 45°

Critical Total %

Planar Sliding (All) 2 11 18.18%

Planar Sliding (Set 2) 2 4 50.00%

Color Strike (Right) Dip Label

Mean Set Planes

1m 77 67

2m 21 71

3m 153 86

Plot Mode Pole Vectors

Vector Count 11 (11 Entries)

Hemisphere Lower

Projection Equal Area

Joint Set 1

Joint Set 2

Joint Set 3

Cut Slope

Friction Angle

Analysis Description Sta. 386+00 - Sta. 393+00 / Planar Sliding Analysis Company CFLHDDrawn By JMA File Name Mormon Lake.dips7Date 6/4/2018, 9:44:28 AM

Project

AZ FLAP 237(1) - Mormon Lake Road

DIPS 7.006

EW

1m

1m

2m

2m

3m

3m

Symbol Feature

Critical Intersection

Color Density Concentrations

0.00 - 1.90

1.90 - 3.80

3.80 - 5.70

5.70 - 7.60

7.60 - 9.50

9.50 - 11.40

11.40 - 13.30

13.30 - 15.20

15.20 - 17.10

17.10 - 19.00

Contour Data Pole Vectors

Maximum Density 18.18%

Contour Distribution Schmidt

Counting Circle Size 1.0%

Kinematic Analysis Wedge Sliding

Slope Dip 64

Slope Dip Direction 115

Friction Angle 45°

Critical Total %

Wedge Sliding 16 55 29.09%

Plot Mode Pole Vectors

Vector Count 11 (11 Entries)

Intersection Mode Grid Data Planes

Intersections Count 55

Hemisphere Lower

Projection Equal Area

Joint Set 1

Joint Set 2

Joint Set 3

Cut Slope

Friction Angle

Analysis Description Sta. 386+00 - Sta. 393+00 / Wedge Sliding Analysis Company CFLHDDrawn By JMA File Name Mormon Lake.dips7Date 6/4/2018, 9:44:28 AM

Project

EW

1m

1m

2m

2m

3m

3m

Color Density Concentrations

0.00 - 1.90

1.90 - 3.80

3.80 - 5.70

5.70 - 7.60

7.60 - 9.50

9.50 - 11.40

11.40 - 13.30

13.30 - 15.20

15.20 - 17.10

17.10 - 19.00

Contour Data Pole Vectors

Maximum Density 18.18%

Contour Distribution Schmidt

Counting Circle Size 1.0%

Plot Mode Pole Vectors

Vector Count 11 (11 Entries)

Hemisphere Lower

Projection Equal Area

Joint Set 1

Joint Set 2

Joint Set 3

Cut Slope

Analysis Description Sta. 386+00 - Sta. 393+00 / Flexuaral Toppling Analysis Company CFLHDDrawn By JMA File Name Mormon Lake.dips7Date 6/4/2018, 9:44:28 AM

Project

EW

1m

1m

2m

2m

3m

3m

Symbol Feature

Critical Intersection

Color Density Concentrations

0.00 - 1.90

1.90 - 3.80

3.80 - 5.70

5.70 - 7.60

7.60 - 9.50

9.50 - 11.40

11.40 - 13.30

13.30 - 15.20

15.20 - 17.10

17.10 - 19.00

Contour Data Pole Vectors

Maximum Density 18.18%

Contour Distribution Schmidt

Counting Circle Size 1.0%

Kinematic Analysis Direct Toppling

Slope Dip 64

Slope Dip Direction 115

Friction Angle 45°

Lateral Limits 10°

Critical Total %

Direct Toppling (Intersection) 1 55 1.82%

Oblique Toppling (Intersection) 2 55 3.64%

Base Plane (All) 1 11 9.09%

Base Plane (Set 2) 1 4 25.00%

Plot Mode Pole Vectors

Vector Count 11 (11 Entries)

Intersection Mode Grid Data Planes

Intersections Count 55

Hemisphere Lower

Projection Equal Area

Joint Set 1

Joint Set 2

Joint Set 3

Cut Slope

Friction Angle

Analysis Description Sta. 386+00 - Sta. 393+00 / Direct Toppling Analysis Company CFLHDDrawn By JMA File Name Mormon Lake.dips7Date 6/4/2018, 9:44:28 AM

Project