CA.FLAP.PLU.CR411(1)._Bucks_Lake_Rd.Geotech_Final.2016.pdf

Bucks Lake Road

CA FLAP PLU CR411 (1)

Final Geotechnical Report

Report No. CA-FX-CR411-16-01

Prepared by:

Federal Highway Administration

Central Federal Lands Highway Division

Geotechnical Services Branch October 2016 i

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page i

Table of Contents

SECTION ONE --INTRODUCTION

1.1. PROPOSED CONSTRUCTION

SECTION TWO --GEOLOGY AND SEISMICITY

2.1. GEOLOGY

2.2. GEOLOGIC HAZARDS

2.3. SEISMIC DESIGN PARAMETERS

SECTION THREE --FIELD EXPLORATION

3.1. SUBSURFACE EXPLORATION PROGRAM

3.2. LABORATORY TESTING PROGRAM

3.3. ROCK SLOPE MAPPING PROGRAM

SECTION FOUR --ANALYSIS AND RECOMMENDATIONS

4.1. ROCK CUT STRUCTURAL STABILITY

4.2. ROCKFALL CATCHMENT DITCH

4.3. REINFORCED SOIL SLOPES (RSS)

4.4. EMBANKMENT CONSTRUCTION

4.5. SHRINK/SWELL RECOMMENDATIONS

4.6. CONSTRUCTION CONSIDERATIONS

SECTION FIVE --LIMITATIONS

SECTION SIX --REFERENCES

TABLES

Table 1: Summary of Kinematic Analysis

Table 2: Summary of CRSP Analysis

Table 3: RSS Design Parameters

Table 4: Summary of RSS Stability Analyses

FIGURES

Figure 1: Location Map

Figure 2: Geology Map

Figure 3: Geotechnical Boring Locations

Figure 4: Isometric Site View ii

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page ii

APPENDICES

Appendix A: Field Exploration Program

Appendix B: Laboratory Test Results

Appendix C: Photos

Appendix D: Rock Slope Mapping and Kinematic Analysis

Appendix E: Colorado Rockfall Simulation Program (CRSP)

Appendix F: Reinforced Soil Slope Analysis

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 1

SECTION ONE--INTRODUCTION

This report presents the results of the geotechnical investigation conducted for the Plumas County, Bucks Lake Road, CA FLAP PLU CR411(1) project. The project involves reconstruction of approximately 1,750 feet of the existing Bucks Lake Road for rockfall hazard mitigation. The project stationing and proposed alignment begins approximately 500 feet east of the intersection of Snake Lake Road (Station 356+14) and extends east to Station 373+50 as shown on Figure 1, Location Map.

Periodic rockfall has occurred at this location since the adjacent rock cut was excavated as part of a roadway widening project in 2013-2014. Rocks vary in size, and on two occasions, exceptionally large (>10 foot) boulders blocked the travel lanes of the road. Poor rock quality, adverse discontinuity orientation, steep cut slopes, adverse slope orientation (north facing) and water seepage all contribute to the rockfall events.

Bucks Lake Road provides access the unincorporated communities of Meadow Valley, Bucks Lake, and to numerous Forest Service roads that access approximately 160,000 acres of federal lands located between the Middle Fork of the Feather River and California State Highway 70.

During summer, alternative access to these areas is available via forest service roads. However, these roads are not maintained during the winter, leaving Bucks Lake Road as the only access route. The proposed reconstruction is anticipated to significantly reduce the risk presented by rockfall hazards.

This report summarized the relevant findings from the geotechnical investigation and provides recommendations pertaining to the June 2016 Design Plans. The geotechnical investigation consisted of rock cut mapping, field subsurface exploration at potential rock cut and embankment fill locations, laboratory testing, correlation of available data, and geotechnical analysis.

1.1. PROPOSED CONSTRUCTION

To reduce the risk associated with the rockfall hazards, various rockfall mitigation methods were evaluated including a rockfall fence, draped mesh, anchored mesh, laying back the cut slope and ditch widening. Based on a technical evaluation of alternatives and costs, the final project proposes to shift the roadway away from the steep cut slope to accommodate a new 20-foot wide rockfall ditch. As a result of this roadway shift further away from the existing cut slope, two reinforced soil slopes (RSS) will be used to reduce the impact of proposed fill slopes related to the roadway realignment. Due to a topographically lower bench from the old roadway alignment, reinforced slopes with maximum face angles of 1V:1H catch existing slopes at maximum heights of 50 feet and 30 feet. Compared to constructing mechanically stabilized earth (MSE) walls at these locations, which would consist of approximately 25-foot high vertical walls with wire-faced rock baskets and imported granular fill material, the RSS alternative has a considerably lower cost due to the re-use of on-site materials as backfill. Additional minor construction elements include safety improvements with new guardrail extending most of the project length including along the top of each RSS location, drainage improvements with super elevation corrections and ditches, and a pavement slump area (near Station 370+00) will be removed and reconditioned as part of the RSS construction.

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 2

SECTION TWO--GEOLOGY AND SEISMICITY

2.1. GEOLOGY

Bucks Lake Road is located within the Sierra Nevada Range of the Cascade-Sierra Mountains.

Geology of the site has been mapped by Hietanen (1973). The alignment is underlain by Quaternary gravel deposits and the orthoquartzite and muscovite phyllite members of the Silurian Shoo Fly Formation. The orthoquartzite is described as round transparent bluish-gray grains of quartz embedded in a fine-grained mixture of quartz and sericite, including beds of white granular quartzite. The muscovite-phyllite is described as fine grained, light beige to medium gray. A geologic map is shown in Figure 2 and a description of the soil and rock encountered from the borings is discussed in more detail in Appendix A.

2.2. GEOLOGIC HAZARDS

Geologic hazards exist from the natural environment, existing roadway condition, and proposed construction. Primary geologic hazards that exist in the vicinity of the project area are slope instability at cut and fill slope locations, rockfall, and to a lesser extent, seismic events.

Slope instability and rockfall hazards exist throughout the roadway alignment and are likely to continue. Slope instability is generally a result of boulders/rock fragments dislodging from over steepened colluvial soil slopes and elevated alluvial terraces, or closely jointed rock mass outcrops.

Rockfall is primarily anticipated to originate from existing and proposed cut slopes and could potentially occur during construction. Rockfall risk is particularly high in the wet winter and early spring months during freeze-thaw cycles, but year-round seepage should be expected in the existing rock cut slope. The adverse slope orientation (north facing) increases the rockfall risk during winter and early spring due to shadows and prolonged icy conditions at this roadway curve location. The proposed catchment ditch will significantly reduce the risk of rock falls impacting traffic since over 95-percent of falling rocks will most likely be retained in the ditch.

2.3. SEISMIC DESIGN PARAMETERS

Two active faults were identified within approximately 10 miles of the project from a USGS Earthquake Hazard Program database search. These are the Bottle Springs Fault and the Haskins Valley Fault. Earthquake damage can be direct or indirect. Direct damage is due to strong shaking and fault rupture that occur mainly along faults in close proximity to the site during an earthquake.

Indirect damage occurs either subsequent to the direct damage or resulting from secondary adjustments to the primary fault rupture.

The American Association of State Highway and Transportation Officials (AASHTO) criteria for Recommended seismic response parameters are based on the AASHTO LRFD Bridge Design Specifications, 7th Edition, 2014, and represents horizontal peak ground acceleration (PGA) with 7 percent probability of exceedance in 75 years (approximate 1000-year return period). The 1000-year return period uniform hazard spectrum for the site (39.9494 latitude and -121.0293 longitude) was obtained in accordance with the AASHTO ground motion maps. Bedrock is exposed

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 3 throughout the project site; therefore the site is classified as Class B according to site class definitions specified in Table 3.10.3.1-1 of AASHTO. Based on these criteria, a peak ground acceleration (PGA) of 0.285 g was assigned to the site.

Based on the long acceleration coefficient SD1 value of 0.211, the site is assigned to seismic hazard Zone 2 in accordance with Table 3.10.6-1 of AASHTO.

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 4

SECTION THREE--FIELD EXPLORATION

3.1. SUBSURFACE EXPLORATION PROGRAM

Central Federal Lands Highway Division (CFLHD) of the Federal Highway Administration (FHWA) geotechnical personnel conducted a subsurface investigation during October 6 to 8, 2015, to characterize the subsurface materials at the existing rock cuts and at potential embankment fill sites that could be RSS or MSE walls. The subsurface exploration program consisted of drilling a total of 4 borings: two borings at the proposed cut slope, one near the proposed RSS, and one to evaluate the existing pavement of Bucks Lake Road. The shallow pavement boring is discussed under separate cover in the Pavement Report. Boring locations are shown on Figure 3, Geotechnical Boring Locations. Subsurface conditions were logged and representative samples were collected and transported to the CFLHD Materials Laboratory in Lakewood, CO, for physical property testing. More detailed descriptions of the work performed, borings logs, and laboratory test data are contained in Appendices A and B, respectively. Subsurface exploration site photos are contained in Appendix C.

Two borings, B-1 and B-2 for the rock cut slope were completed to depths ranging from 50 to 50.4 feet below the existing ground surface (elevation 3652.6 and 3657.0 feet). Both borings encountered interbedded gray brown phyllite and lighter gray quartzite. B-1 located furthest west on the rock outcrop, contained more quartzite while B-2, located closer to the rockfall chute area, contained mostly phyllite. RQD in the phyllite ranged from 0 to 35, which is notably lower than the RQD of the quartzite units, which was highly variable ranging from 0 to 100 and averaging approximately 48 and 67 in B-1 and B-2, respectively. The phyllite was observed to generally be highly weathered and very weak, while the quartzite was observed to generally be moderately weathered and medium strong.

Boring B-3 was drilled along the roadway shoulder near the guardrail for the reinforced soil slope (RSS) 52 feet below the ground surface (elevation 3592.0 feet). Drilling started with auger and advanced to a depth of approximately 12 feet (elevation 3632.0 feet), with two Standard Penetration Tests (SPT) performed at 5 and 10 feet (elevation 3625.0 and 3630.0 feet). Coarse gravel and probable cobbles and boulders were encountered at 12 feet depth (elevation 3632.0 feet), and drilling method was switched from auger to coring due to hard drilling. The coarse gravel and cobble sized rock fragments were encounter to a depth of approximately 42 feet below the ground surface (elevation 3602.0 feet), where a clayey sand unit was encountered to the borehole termination at 52 feet below the ground surface (elevation 3592.0 feet).

3.2. LABORATORY TESTING PROGRAM

Laboratory tests were completed on select soil and rock samples recovered for the field exploration program in general accordance with the American Association of State Highway and Transportation Officials (AASHTO) and ASTM testing methods. The laboratory testing program was completed to provide data for engineering studies and to classify the materials into similar geologic groups. The testing program included gradation, Atterberg Limits, organic content, Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 5 corrosivity, and R-values on soil samples from B-3 and B-4 and uniaxial compression and direct shear strength tests on rock samples from B-1 and B-2. More detailed descriptions of the laboratory test data are contained in Appendices B.

Soil test results indicated clayey and silty sand material, classifying by AASHTO as A-2-6(1) to A- 1-b(0) and SC to SC-SM by USCS. The gravels classified as clayey to silty gravel by AASHTO as A-1-a(0) and GC-GM by USCS. R-values were 65 and 55 in B-3 and B-4, respectively. Organic contents were low, ranging from 2.2 to 4.0 percent. Corrosion tests were run in samples from B-3 and resulted in pH of 7.0 and resistivity of 7,290 ohm-cm.

Rock test results for compressive strengths of intact rock were only performed on quartzite samples because the phyllite RQD was too low to produce via samples for the testing method. Nine samples were tested from B-1 and B-2 quartzite materials and the results ranged from 2,280 psi to 13,040 psi compressive strength. The results can be grouped into three sets; (1) failures along existing joints (4 samples) ranging from 2,280 to 3,860 psi; (2) failures along weak rock (3 samples) ranging from 5,110 to 6,090 psi; and (3) intact rock strength (2 samples) ranging from 11,140 to 13,040 psi.

The sliding friction shear test was conducted on two rock samples obtained from borings B-1 at 7.8 feet and B-2 at 11.0 feet in general accordance with ASTM D 5607. The results of these tests indicate residual cohesion of 6.7 psi to 9.7 psi and residual friction angles of 36.6 degrees and 46.4 degrees in B-2 and B-1 samples, respectively.

3.3. ROCK SLOPE MAPPING PROGRAM

CFLHD geotechnical personnel also conducted geologic field mapping and kinematic analysis on October 27, 2015, of proposed rock cuts to evaluate rockfall mechanisms and rock cut stability.

Window mapping was conducted at three locations along the existing rock cuts to characterize discontinuities and estimate the shear strength (dip angle and direction, estimation of surface roughness, observation of infilling materials, estimation of persistence and spacing). Program results of the rock slope mapping and kinematic analysis are presented in Appendix D.

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 6

SECTION FOUR--ANALYSIS AND RECOMMENDATIONS

This section provides analysis and recommendations for the rock cut structural stability, the rockfall catchment ditch, reinforced soil slopes (RSS), embankment construction, and construction considerations.

4.1. ROCK CUT STRUCTURAL STABILITY

The existing rock cut averages approximately 50-feet in height and extends approximately 1,000 feet in length, crossing three different geologic units. The first approximately 300-feet of the rock cut in meta-sedimentary red shale will not be impacted as part of this project because it has not experienced rockfall issues, only minor raveling that is generally captured in the existing ditch.

Figure 4 presents a 3-dimensional isometric site view of the rock cuts from a detailed survey of the existing site conditions which shows the surface slope angle variations and orientation of the rock cuts with respect to the existing roadway.

As the roadway turns the corner, the rock type changes to a lighter colored slate, phyllite and schist that impose the highest rockfall risk on the project due to the formation of a rockfall chute adversely oriented to carry or transport rocks directly into the roadway travel lanes. This unit extends approximately 300 feet in length and increases in rock cut height to approximately 70-feet in maximum height with a face angle varying from 1V:1H to 1V:1/2H. This rockfall section was used in the analysis of the rockfall protection methods and catchment ditch design because it represents the most critical section on the project. This middle section of the rock cut is adjacent to the existing pullout, which was formed from a combination of the existing rock cut excavation material and rockfall debris that has been broken down and removed from the roadway by county maintenance equipment.

The final third section of the rock cut transitions into a light gray quartzite section that extends approximately 400 feet in length and decreases in height from approximately 60-feet maximum height to the roadway elevation to the west and contains harder intact rock strength, but still has adversely oriented discontinuity sets. The bench access was excavated in this section of the rock cut to facilitate the rock cut excavation.

The majority of the bedrock observed consisted of quartzite and phyllite with variable discontinuity orientations and variable weathering grades. Rock slope stability is structurally controlled by the orientation, spacing, and persistence of discontinuities within the rock mass (joints, foliation planes, faults, and shear zones); and the shear strength of the discontinuities (in-filling material, roughness, and pore-water pressure). Structural geologic mapping data and kinematic analysis results are presented in Table 1 and Appendix D.

Primary failure modes are wedge failures that potentially daylight into the existing rock cut slope and secondary failure modes are planar features that also potentially daylight into the existing rock cut slope.

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 7

Table 1: Summary of Kinematic Analysis

R O

C K

C U

T

ID

STATION

C U

T S

LO

P

E

LE

N

G T

H

FT

W

IN

D O

W

EXISTING CUT POTENTIAL FAILURE MODES

START END

MAX

HEIGHT

(FT)

MAX

SLOPE

Angle

PRIMARY SECONDARY

Discontinuity Discontinuity

Angle (Variation)

Discontinuity Discontinuity

Angle (Variation)

367+00 365+45 155 W1 75 45˚ Wedge

J1/J2 20˚/11˚ NA NA

365+45 364+30 115 W2 100 75˚

Wedge J1/J2 J1/J4 J1/J6 J4/J6

30˚/8˚ 30˚/9˚ 30˚/25˚ 9˚/25˚

Planar J1 J2

30˚ 8˚

364+30 363+00 130 W3 120 80˚ Wedge J1/J2 J1/J3

40˚/5˚ 40˚/32˚

Planar J1 J2

40˚ 5˚

4.2. ROCKFALL CATCHMENT DITCH

Various rockfall mitigation methods were evaluated including a rockfall fence, draped mesh, anchored mesh, laying back the cut slope to a lower slope face angle, and ditch widening to reduce the risk associated with the rockfall hazards identified in the kinematic analysis in Section 4.1 above. Laying back the cut slope is not a viable option due to environmental constraints on the slope above the existing cut slope that cannot be disturbed. The rockfall protection methods, including rockfall fence, draped mesh, and anchored mesh, all cost more for installation and maintenance than the 20-foot wide rockfall catchment ditch and roadway realignment alternative.

Therefore, the catchment ditch construction was determined to be the optimum mitigation method for this project site.

A rockfall catchment area is defined as the area between the roadway edge of shoulder and the base of a cut slope used to restrict a high percentage of rockfalls from reaching the roadway. The use of catchment areas to contain and restrict rockfall from reaching the roadway is one of the best and most effective rockfall protective measures. Colorado Rockfall Simulation Program Version 5.0 (CRSP-3D) was used to analyze the ditch catchment effectiveness of the existing slope conditions compared to the proposed combinations of ditch widths and cut slope geometries. CRSP-3D accounts for irregularities in the existing slope profile utilizing the actual slope’s cross section in the analysis. This feature allows for greater accuracy in the results as it captures potential launching features attributing to decreased percent rockfall containment.

Slope station 362+50 was chosen to be representative of the typical critical slope with respect to cut height, slope face angle, minimal ditch width and potential launching features. From field observations it was assumed that spherical rocks ranging from 3 to 12 feet could randomly fall from the top of slope and from the mid-slope bench. Greater detail on the CRSP methodologies

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 8 and material parameters used in the analysis are given in Appendix E.

From the analysis, a 20-foot wide standard catchment ditch sloped back into the slope at 14 degrees (1V:4H) is recommended below proposed rock slopes. This ditch greatly increases the estimated percent of rockfall contained from the existing to proposed condition, as shown in Table 2. Routine ditch cleaning should be included in the county’s maintenance plan to avoid decreased rockfall retention.

Table 2: Summary of CRSP Analysis

Existing Conditions 2-Ft Ditch, 0-Ft shoulder. Dropping 1000 Spherical Rocks From Each Rock Source Area

Rock Source Area

Rock Size

Analysis Partitions

Percent Passing

Percent Retained In Ditch

Height on Lower

Bound of Slope to

Height on Upper

Bound of Slope

Source Area Description

0 - 65 Cut Face Below Bench 3-12

Bottom of Ditch 91%

15% Inboard Shoulder 85%

65 - 107 Above Bench 3-12

Bottom of Ditch 21%

79% Inboard Shoulder 21%

Proposed Conditions 20-Ft Gravel Ditch, Dropping 1000 Spherical Rocks From Each Rock Source Area

Rock Source Area

Rock Size

Analysis Partitions

Percent Passing

Percent Retained In Ditch

Height on Lower

Bound of Slope to

Height on Upper

Bound of Slope

Source Area Description

0 - 65 Cut Face Below Bench 3-12

Bottom of Ditch 95%

99% Inboard Shoulder 1%

65 - 107 Above Bench 3-12

Bottom of Ditch 20%

99% Inboard Shoulder 1%

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 9

4.3. REINFORCED SOIL SLOPES (RSS)

Roadway realignment to add the 20-foot wide rockfall ditch described in the Section 4.2 above will require embankment fill slopes on the outboard lane. Based on the observed site materials and laboratory testing, these embankment fills could be constructed at 1V:2H slopes or flatter to maintain slope stability and facilitate vegetation growth. To avoid large embankments exceeding 70-feet in height that would require imported material and potentially impact the Spanish Creek streambed below the roadway, the fill embankments can be steepened with mitigation treatments such as reinforced soil slopes (RSS) or with an mechanically stabilized earth (MSE) wall. An MSE wall at these locations would be approximately 25-feet high with wire-faced rock baskets and imported granular fill material. While both an MSE wall and an RSS are technically feasible options, the RSS alternative will cost considerably less due to the re-use of the existing on site materials as backfill and no need for a special subcontractor to design and construct walls.

RSS will consist of compacted on-site fill and geosynthetic reinforcement vertically spaced at 3-foot intervals for maximum total heights of 50 feet and 30 feet at Station 360+00 and 365+00, respectively. The analyses and recommendations for the RSS are in general accordance with the design methodologies and guidelines in FHWA Publication NHI-10-024 and NHI-10-025, Volumes 1 and 2, respectively, entitled “Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes”, dated November 2009.

Soil and rock strength properties used in RSS analysis were selected based on the results of the subsurface investigation and laboratory testing program and are summarized in Table 3.

Table 3: RSS Design Parameters

Material Unit Weight γ, (pcf)

Friction Angle ϕ, (deg)

Cohesion Intercept c, (psf)

RSS Fill 130 36 0

Gravels and Cobbles 130 38 0

Clayey Sand 125 36 500

Rock 135 38 2000

RESSA, a two dimensional limit equilibrium computer program from ADAMA Engineering was used in the analysis of the RSS. The Bishop method of slices was used with isotropic soil and rock parameters. Analyses were performed to determine minimum embedment lengths, spacing, and tensile strength required for a minimum static factor of safety of 1.3 and seismic factor of safety of

1.1. A 250 pounds per square foot surcharge load was included in the long-term static analyses for traffic loading on the roadway. The RSS design calculation are included in Appendix F and summarized in Table 4.

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 10

Table 4: Summary of RSS Stability Analyses

Stationing Proposed

Maximum Slope Ratio (V:H)

Proposed Maximum Slope

Height (feet)

Length of Reinforcement

(feet)

Static Factor of

Safety

Seismic Factor of

Safety

360+00 to 363+00 1:1 50 35 1.49 1.11

365+00 to 370+50 1:1 30 21 1.44 1.20

The embankment side slopes should be constructed as an RSS and keyed into the general embankment fill. Construct the slopes with maximum heights and slope ratios, and minimum reinforcement lengths as summarized on Table 4. The geogrid reinforcement should have minimum nominal long term design strength (LTDS) of 1,000 pounds per foot and maximum vertical spacing of no more than 3 feet. Extend the top three layers of geogrid from the face of slope to the far edge of the traveled way of the roadway. Place a rolled erosion control mat over the face of the RSS to aid in revegetation. Incorporate a back-drain system to alleviate subsurface water and control surface water drainage to prevent water running directly over the RSS.

4.4. EMBANKMENT CONSTRUCTION

The remainder of the embankment areas should be construction with traditional embankment construction methods. Construct traditional embankments with a maximum slope ratio of 1V:2H to maintain slope stability and promote revegetation of the slope. An erosion control mat or other erosion mitigation devices should be placed on the completed slopes to assist with revegetation requirements. Construct embankments in accordance with Section 204 of FP-14 and the project

SCR.

4.5. SHRINK/SWELL RECOMMENDATIONS

On-site soils encountered within the anticipated excavation and construction limits generally consist of alluvial sands with varying amounts of gravels and silt and clay/silt soils. It is estimated that these soils will have a 5% shrink percentage, corresponding to a shrink/swell factor of 0.95.

The recommended shrink/swell factor is 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.

4.6. CONSTRUCTION CONSIDERATIONS

Specifications: All geotechnical recommendations stated above are incorporated into the special contract requirements (SCR) to amend or are already incorporated within the FHWA Standard Specification for Construction of Roads and Bridges on Federal Highway Projects; known as FP- 14.

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 11

Roadway Excavation: Excavate using equipment capable of removing the material while preventing material from escaping outside the construction limits.

If bedrock is encountered laterally within the proposed reinforcement lengths for the RSS during construction, a member of the CFLHD geotechnical team should be contacted for evaluation.

Based on the subsurface investigation and surface geologic mapping, the bedrock is expected to be rippable near the surface; however, final determination of bedrock rippability is the responsibility of the contractor. The quantity of rock excavation may be limited, as the CO’s discretion. If groundwater is encountered, dewater and stabilization may be required to construct the RSS.

Dewatering and stabilization methods for RSS construction will depend on conditions encountered.

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 12

SECTION FIVE--LIMITATIONS

The recommendations in this report are based on the data obtained from exploratory borings, 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.

Bucks Lake Road, CA FLAP PLU CR411(1) October 2016 Page 13

SECTION SIX--REFERENCES

American Association of State Highway and Transportation Officials (AASHTO), 2014, LFRD BRIDGE DESIGN SPECIFICATIONS, 7th Edition.

Andrew, R.D., 1994. “The Colorado Rockfall Hazard Rating System,” Colorado Dept. of Transportation, report # CTI-CDOT-2-94.

U.S. Department of Transportation, Federal Highway Administration, 2016, “Plans for Proposed CA FLAP PLU CR411(1), Bucks Lake Road Stabilization, Plumas National Forest, Plumas County”, dated June 2016.

Federal Highway Administration (FHWA), 2009, “Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes – Volume 1”, Publication FHWA-NHI- 10-024, dated November 2009.

Federal Highway Administration (FHWA), 2009, “Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes – Volume 2”, Publication FHWA-NHI- 10-025, dated November 2009.

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

ADAMA Engineering Inc, Computer Program, ReSSA, Version 3.0, Copyright 2013.

Hietanen, Anna, 1973, “Geology of the Pulga and Bucks Lake Quadrangles, Butte and Plumas Counties, California” U.S. Geological Survey, Professional Paper 731, scale 1:48,000.

http://geohazards.usgs.gov/cfusion/qfault/query_main_AB.cfm http://geohazards.usgs.gov/cfusion/hazfaults_2014_search/query_main.cfm

“National Seismic Hazard Map”, United States Geological Survey (USGS), 2008, website:

http://earthquake.usgs.gov/research/hazmap

Oregon Department of Transportation Highway Division. 1987. “Soil and Rock Classification Manual.”

Pierson, L.A., C.F. Gullixson, and R.G. Chassie, 2001, Rockfall Catchment Area Design Guide – Final Report, Oregon Dept. of Transportation Research Group pub. No. SPR-3(032), November 2001.

Rogers, J. David. Environmental & Engineering Geoscience, Vol. XII, No. 2, May 2006, pp.161-

179. “Subsurface Exploration Using the Standard Penetration Test and the Cone Penetrometer Test.”

Summit Peak Technologies, Computer Program, Colorado Rockfall Simulation Program, CRSP- 3D, Version 5.0, Copyright 2012.

http://geohazards.usgs.gov/cfusion/qfault/query_main_AB.cfm http://geohazards.usgs.gov/cfusion/hazfaults_2014_search/query_main.cfm http://earthquake.usgs.gov/research/hazmap

Dominic.Monarco Text Box

APPENDIX A

FIELD EXPLORATION PROGRAM

CA FLAP PLU CR 411(1) A-1

APPENDIX A

FIELD EXPLORATION PROGRAM

A.1 INTRODUCTION

The Central Federal Lands Highway Division (CFLHD) Geotechnical Section completed a field exploration program for CA FLAP 209, Bucks Lake Road, between October 6 and 27, 2015. The scope of work included drilling a total of four borings and geologic surface mapping of the existing rock cuts. The subsurface drilling exploration consisted of two borings in the existing cut slope, one RSS boring, and one pavement boring. The drilling component of the field exploration program was coordinated and observed by CFLHD Geotechnical personnel. Field exploration locations are illustrated on the Geotechnical Boring Locations in Figure 3. Individual boring logs are attached. These logs represent a compilation of field and laboratory data and description of the soil and rock by CFLHD Geotechnical personnel. The methods used to conduct the field exploration program are described below. Photos of drilling equipment and field exploration activities are included in Appendix C. All rock and soil samples collected during the field exploration program were transported to the CFLHD Materials Laboratory in Lakewood, Colorado for testing. A summary of the laboratory testing program is provided in Appendix B.

A.2 EXPLORATIONS

Borings

Taber Drilling of Sacramento, California provided the drilling services for all four borings.

Borings were completed using a CME 55 truck mounted drill rig.

Two borings, B-1 and B-2 for the rock cut/slide slope were completed to depths ranging from 50 to 50.4 feet below the rock slope. Both of the borings were drilled using 2.4-inch I.D. HQ3 size coring and were terminated at the depth of interest.

Boring B-3 was drilled along the roadway shoulder near the guardrail for the reinforced soil slope (RSS) 52 feet below the ground surface. Drilling started with auger and advanced to a depth of approximately 12 feet, with two Standard Penetration Tests (SPT) performed at 5 and 10 feet. Coarse gravel and probable cobbles and boulders were encountered at 12 feet depth, and drilling method was switched from auger to coring due to hard drilling with limited drilling equipment capabilities.

The shallow (less than 5 feet depth) boring B-4 was drilled through the existing pavement. The discussion of that boring is available under separate cover in the Pavements Report.

The location and elevation of individual borings were estimated relative to features shown on the plan set. Boring locations are listed on individual boring logs and are shown below in Table A-1.

CA FLAP PLU CR 411(1) A-2

Following drilling activities, field personnel backfilled the borings in accordance with applicable local, state, and federal regulations.

TABLE A1 – Field Exploration Locations

Approximate Station

Offset (ft)

Exploration Designation

Approx. Depth (ft)

Below Ground Surface

Approx.

Depth to

Bedrock (ft)

Exploration Purpose

364+40 120 RT B-1 50.4 0.0 Rock cut slope 362+80 115 RT B-2 50.0 0.0 Rock cut slope

369+40 12 LT B-3 52.0 N/A RSS

357+50 7 LT B-4 4.0 N/A Pavement

Geologic Mapping

Geologic mapping of surface rock outcrops or existing cut slopes was completed on October 27, 2015 by CFLHD Geotechnical personnel. Geologic mapping of surface rock outcrops or existing cuts, in similar geological formations to that which the proposed alignment will be constructed, provides fundamental information on site conditions, and is often the primary basis for rock cut and rock reinforcement design. A summary of the geologic mapping methods used, as well as the analysis of collected structural geology data, is presented in Appendix D.

A.3 SOIL AND ROCK SAMPLING

Borings

Rock samples were collected from borings B-1 and B-2 using HQ wireline coring method.

During coring, cuttings were removed from the borehole by circulating water down the drill rods and back up the annulus of the boring. Core runs ranged between approximately 1 to 4 feet in length. Shorter runs were used in an attempt to improve recovery in low quality rock. Percent recovery and rock quality designation (RQD) values are shown on the boring logs. Percent recovery is the ratio of the length of recovered core to the total length of the core run. RQD is the ratio of the sum of the length of intact core pieces greater than 4 inches long in a run to the total length of the core run. During drilling, the core was logged by CFLHD Geotechnical personnel, then stored in cardboard core boxes and transported to the CFLHD Materials Laboratory for compression and shear testing.

Disturbed samples were obtained from the boring B-3 at 5 and 10 feet depths in accordance with the SPT, the procedures of which are detailed in AASHTO T-206. The SPT involves driving a 2-inch outside diameter, 1.375-inch inside diameter split spoon sampler a depth of 18 inches with a

CA FLAP PLU CR 411(1) A-3

140-pound hammer falling a distance of 30 inches. The number of blows required to advance the split-spoon sampler through each of the 6-inch increments was recorded. The SPT resistance, or N-value, is defined as the number of blows required to drive the sampler over the second and third 6-inch increments. The N-value provides a means for evaluating the relative density of cohesionless (granular) soils and consistency or stiffness of cohesive (fine-grained) soils. An energy corrected N-value, N60, is used to standardize the energy levels of the hammer system in the SPT to 60% efficiency. An efficiency of 80% was assumed for this drilling effort for the automatic hammer system. Representative portions of the split-spoon sample obtained in conjunction with the SPT were placed in plastic baggies and transported to the CFLHD Materials Laboratory for possible testing.

A.4 SOIL AND ROCK CLASSIFICATION SYSTEMS

During the completion of borings, CFLHD Geotechnical personnel collected bulk soil and rock core samples and prepared field logs of the borings. Soil identification and descriptions, as shown on the field logs, are based on ASTM D2488, a systematic process for identifying and describing individual soil samples by visual and manual means. When sufficient laboratory testing was completed, select samples from borings were classified using the Unified Soil Classification System (USCS) and American Association of State Highway and Transportation Officials (AASHTO) soil classification system. Both the visual soil identification system and the referenced soil classification systems are summarized in the attached Soil Classification Field Reference. Rock samples were classified based on the stratigraphic structure, rock strength, degree of weathering, and other properties. The rock classification system is summarized in the attached Rock Classification Field Reference.

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C

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GP

GM

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SP

SM

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Unified Soil Classification System

SOIL CLASSIFICATION CHART & LEGEND

SILTY GRAVELS WITH OR WITHOUT SAND

HIGHLY ORGANIC SOILS

POORLY-GRADED SANDS WITH OR WITHOUT

GRAVEL

CLEAN SANDS

WITH LESS THAN

15% FINES

GRAVELS WITH

15% OR MORE

FINES

GRAVELS

MORE THAN HALF

COARSE

FRACTION IS

LARGER THAN NO.

4 SIEVE

MAJOR DIVISIONS TYPICAL NAMES

WELL-GRADED GRAVELS WITH OR WITHOUT

SAND

POORLY-GRADED GRAVELS WITH OR

WITHOUT SAND

ORGANIC SILTS OR CLAYS OF HIGH

PLASTICITY WITH OR WITHOUT SAND OR

GRAVEL

PEAT AND OTHER HIGHLY ORGANIC SOILS

CLAYEY SANDS WITH OR WITHOUT GRAVEL

C O

A R

S E

-G R

A

IN

E D

S O

IL

S

M O

R E

T H

A N

H A

LF

IS

C O

A R

S E

R T

H A

N N

O . 2

S

IE

V

E

NOTE: Coarse-grained soils with between 5% and 12% passing the No.200 sieve and fine-grained soils with limits plotting in the gray zone on the plasticity chart have dual classifications.

SILTS AND CLAYS

LIQUID LIMIT 50% OR LESS

Unconfined Compression No Recovery

SILTS AND CLAYS

LIQUID LIMIT GREATER THAN 50%

UC

NR

FI

N

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R A

IN

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S M

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H A

N H

A

LF

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F

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R T

H A

N N

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S

IE

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SANDS WITH 15%

OR MORE FINES

SANDS

MORE THAN HALF

COARSE

FRACTION IS

FINER THAN NO. 4

SIEVE SIZE

INORGANIC CLAYS OF HIGH PLASTICITY

WITH OR WITHOUT SAND OR GRAVEL

Liquid Limit Plastic Index Moisture Content Dry Density Non Plastic No Valve

Water Level at Time of Drilling

Stabilized Water Level

CLEAN GRAVELS

WITH LESS THAN

15% FINES

Abbreviations

WELL-GRADED SANDS WITH OR WITHOUT

GRAVEL

CLAYEY GRAVELS WITH OR WITHOUT SAND

INORGANIC SILTS OF LOW TO MEDIUM

PLASTICITY WITH OR WITHOUT SAND OR

GRAVEL

INORGANIC CLAYS OF LOW TO MEDIUM

PLASTICITY WITH OR WITHOUT SAND OR

GRAVEL

LL

PI

W

DD

NP

NV

SILTY SANDS WITH OR WITHOUT GRAVEL

ORGANIC SILTS OR CLAYS OF LOW TO

MEDIUM PLASTICITY WITH OR WITHOUT

SAND OR GRAVEL

INORGANIC SILTS OF HIGH PLASTICITY WITH

OR WITHOUT SAND OR GRAVEL

Use primary colors or hyphenated compound primary colors. Use "mottled" or "streaked" if necessary.

4. Color Dry Dry to touch, dusty Moist Damp but no visible water Wet Visible free water

5. Moisture Content

Flat Width/Thickness >3 Elongated Length/Width >3

Flat & Elongated Meets both of the above

Applies to sand, gravel, cobbles and boulders.

Length, width and thickness refer to the greatest, intermediate and least dimensions, respectively.

6c. Particle Shape

N Density N Consistency

Unconfined Compressive Strength qu

(tsf)

Undrained Compressive Strength su

(tsf)

Behavior

0-4 Very Loose 0-1 Very Soft <0.25 <0.125 Extrudes between fingers when squeezed

5-10 Loose 2-4 Soft 0.25-0.50 0.125-0.25 Remolded by light finger pressure

11-30 Medium Dense 5-8 Firm 0.50-1.00 0.25-0.50

Imprinted easily with fingers, remolded by strong finger pressure

31-50 Dense 9-15 Stiff 1.00-2.00 0.50-1.00 Imprinted with considerable finger pressure, indented by finger nail

>50 Very Dense 16-30 Very Stiff 2.00-4.00 1.00-2.00 Barely imprinted by fingers or indented by finger nail

>30 Hard >4.00 >2.00 Not imprinted by fingers or difficult to indent with finger nail

SAND & GRAVEL SILT AND CLAY

3. Consistency and Density:

Angular Sharp edges and relatively plane sides.

Subangular Same as angular with rounded edges.

Subrounded Nearly plane sides but well-rounded corners and edges.

Rounded Smooth curved sides and no edges.

Well-

Rounded Very Smooth surfaces, spherical or ovular, no edges.

6b. Particle Angularity Applies to coarse sand, gravel, cobbles and boulders.

Sieve < #200 Flour or smaller

Fine > #200 to #40 Flour to sugar Medium #40 to #10 Sugar to rock salt Course #10 to #4 Rock salt to pea-sized

Fine #4 to 3/4 in. Pea-sized to thumb Coarse 3/4 in. to 3 in. Tumb to fist Cobble 3 in. to 12 in. Fist to basketball

Boulders > 12 in. Larger than Basketball

Material

Gravel

6a. Particle Size

Silt or Clay

Sand

Particle Size Approximate Scale

Example, fine-grained soil: Lean CLAY with Sand (CL)- stiff, brown, moist, medium plasticity, laminated Example, coarse-grained soil: Silty SAND with Gravel (SM)-medium dense, gray, wet, fine to coarse grained, angular to subangular gravel, weakly cemented Example, fine-grained soil (Long Form):

Clayey GRAVEL with SAND (CL-ML)- loose to soft, dark brownish green to pale brownish gray, wet; fine to medium grained, angular, flat sand; coarse grained, rounded elongated gravel, some chert, trace coarse gravel, and cobbles, medium plasticity, dessicated, weak cementation, low dry strength, rapid dilatancy, moderate HCL reaction, hydrocarbon odor, iron oxide staining, alluvium fill, (Quaternary Alluvium), Additional Description.

1. Group Name (Pg. 3) 9.

2. Group Symbol (Pg. 3) 10.

3. Consistency / Relative Density (Pg. 1) 11.

4. Color (Pg. 1) 12.

5. Moisture (Pg. 1) 13.

6. Particle Size / Shape / Angularity (Pg. 1) 14.

7. Plasticity (Pg. 2) 15.

8. Structure (Pg. 2)

Odor (Pg. 2)

Staining (Pg. 2)

Cementation (Pg. 2) Organics Dry Strength (Pg. 2) Dilatancy (Pg. 2) HCL Rxn (Pg. 2)

Weak Crumbles with little finger pressure Moderate Crumbles with considerable finger pressure Strong Will not crumble with finger pressure

Intact coarse-grained soil

9. Cementation

Nonplastic Thread cannot be rolled at any water content.

Low The thread can barely be rolled and the lump cannot be formed when drier than the plastic limit.

Medium The thread is easy to roll and not much time is required to reach the plastic limit. The thread cannot be rerolled after reaching the plastic limit. The lump crumbles when drier than the plastic limit.

High It takes considerable time kneading and rolling to reach the plastic limit. The thread can be rerolled several times after reaching the plastic limit. The lump can be formed without crumbling when drier than the plastic limit.

Toughness test: Shape the specimen into an elongated pat and rolled on a smooth surface or between the palms into a thread ~1/8”. If the sample is too wet to roll, it should be allowed to dry. Fold the thread and reroll repeatedly until the thread crumbles at a diameter of ~1/8”. This will be near the plastic limit. Note the pressure required to roll the thread near the plastic limit and the strength of the thread. After the thread crumbles, the pieces should be lumped together and kneaded until the lump crumbles. Note the toughness during kneading.

On the basis of observations made during the toughness test, describe plasticity.

7. Plasticity

None No visible reaction Weak Some reaction, bubbles forming slowly Strong Violent reaction, with bubbles forming immediately

13. HCL Reaction 14. Odor 15. Staining None None

Chemical Hyrodcarbon Hyrodcarbon Iron Oxide

Organic

None No visible change Slow Water appears slowly during shaking and does not disappear or disappears slowly during squeezing.

Rapid Water appears quickly during shaking and disappears quickly during squeezing.

12. Dilatancy

1. Mold soil, adding water if necessary, into ~1/2” diameter ball with soft but not sticky consistency.

2. Smooth in palm of one hand with knife blade. Shake horizontally, striking the side of the hand vigorously against the other hand several times. Note the reaction of water appearing on the surface.

4. After Dilatancy has been determined perform the Toughness test (see explanation in #7).

3. Squeeze by closing the hand or pinching the soil between fingers. The reaction is the speed with which water appears while shaking and disappears while squeezing.

None Crumbles into powder with mere pressure of handling.

Low Crumbles into powder with some finger pressure.

Medium Breaks into pieces with considerable finger pressure.

High Cannot be broken with finger pressure, will break between hard surface and thumb.

Very High Cannot be broken between hard surface and thumb.

1. Mold a ball ~1” diameter until it has the consistency of putty, adding water if necessary.

2. From the ball, make at least 3 ½” diameter balls. Allow to air dry.

3. If the specimen contains natural dry lumps, those that are ~1/2” diameter may be used in place of molded balls.

4. Test the strength of the dry balls or lumps by crushing between the fingers.

11. Dry Strength

Stratified Alternating layers > 1/4 inch, note thickness.

Laminated Alternating layers < 1/4 inch, note thickness.

Fissured Contains shears or separations along planes of weakness.

Slickensided Shear planes appear polished or glossy, sometimes striated.

Blocky Cohesive soil can be broken down into harder, angular lumps.

Lensed Inclusion of small pockets of different soils, note thickenss.

Homogeneous Same color and appearance throughout.

Mottled Spots or patches possessing no apparent pattern Varved Distinct laminations of lacustrine sediments predominantly clayey

Desiccated Shrinkage cracks due to dehydration of fine-clayey soil

8. Structure Terms

0.0 - 9.4 ft QUARTZITE, Dark gray with white streaks AR 1 Quartzite, dark gray with white streaks. Drove casing to 5'.

RCH 1 Rec. 2.3 ft of slough (0.7') and 1.7' of quartzite, dark gray with white streaks, moderately to slightly weathered, medium strong (R3), joints are moderate angle, close with iron staining, rough. Lost water return at 6'.

RCH 2 Rec. 2.1 ft of quartzite, dark gray with white streaks, moderately to slightly weathered, medium strong (R3), joints are at a low to moderate angle, close with iron staining, rough.

No water return. 12 minute run.

9.4 - 17.5 ft PHYLLITE, Gray to brown, decomposed RCH 3 No recovery.

RCH 4 No recovery.

RCH 5 No recovery.

RCH 6 Rec. 1.9 ft of quartzite, dark gray with white streaks, moderately to slightly weathered, medium strong (R3), joints are at a low angle, close with iron staining, rough. No water return. 10 minute run.

17.5 - 25.4 ft QUARTZITE, Dark gray with white streaks

RCH 7 Rec. 1 ft of quartzite, dark gray with white streaks, moderately to slightly weathered, medium strong (R3), joints are moderate angle, close with iron staining, rough. No water return. 4 minute run.

RCH 8 Rec. 1 ft of quartzite, dark gray with white streaks, highly to moderately weathered, medium strong (R3), joints are at a low to moderate angle, close with iron staining, rough.

No water return. 7 minute run.

25.4 - 33.5 ft PHYLLITE, Gray to brown RCH 9 Rec. 1.7 ft of gray brown

AR

RCH

RCH

RCH

RCH

RCH

RCH

RCH

RCH

RCH

3693.6

3685.5

3677.6

2.30 100%

2.10 100%

0.00 0%

0.00 0%

0.00 0%

1.90 63%

1.00 100%

1.00 20%

1.70 34%

Description: (Density, Color, Type, Moisture, Other)

R un

/S am p N

o. Length Recov.

feet

% Rec.

Sheet 1 of 2Date: October 2015Project Name: Bucks Lake Road, CA FLAP PLU CR411(1)

Boring Location: STA 364+40, 120 ft RT

Coordinates:

Drill: CME 55 Track

Field Logged By: C. Martinez

Revisions/Final By: C. Martinez

Depth Elevation

(feet)

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

CENTRAL FEDERAL LANDS HIGHWAY DIVISION

BORING LOG

Driller: Taber Drilling G ra ph ic L og

RQD

SPT

Blows per 6 in

Boring No. B-1

Type of Boring: Auger/Core

Casing Used: HQ3

Boring Began: 10/6/15

Ground Elev: 3703.0 ft

Water Depth:

Date:

Time:

Size: 2.4"

Completed: 10/6/15

Weather: Sunny

U .S

.C .S

B O

R

IN

G L

O G

B U

C K

S L

A K

E .G

P J

S W

IF

T

TR

A

IL

.G

P J

/7

/1

RCH 10 Rec. 2.5 ft of phyllite (1.2'), gray brown, highly weathered, very weak (R1), folliated, high to moderate angle, very close, smooth and 1.3' of quartzite, gray, moderately weathered, weak (R2), joints are moderate angle, close. No water return. 6½ minute run.

33.5 - 50.4 ft QUARTZITE, Gray to light gray

RCH 11 Rec. 2.5 ft of quartzite, gray, moderately weathered, weak (R2), joints are moderate to high angle, close. No water return. 6 minute run.

RCH 12 Rec. 2.3 ft of quartzite, gray, moderately weathered, weak (R2), joints are moderate to high angle, close. No water return. 5 minute run.

RCH 13 Rec. 3.1 ft of quartzite, gray to light gray, moderately weathered, weak (R2), joints are moderate to high angle, close. No water return. 5 minute run.

RCH 14 Rec. 1.5 ft of quartzite, light gray, moderately weathered, weak (R2), joints are moderate to high angle, close. No water return. 8 minute run.

RCH 15 Rec. 3.9 ft of quartzite, light gray, moderately weathered, weak (R2), joints are moderate to high angle, close. No water return. 6 minute run.

RCH 16 Rec. 0.9 ft of quartzite, light gray, moderately weathered, weak (R2), joints are moderate to high angle, close. No water return. 2 minute run.

BHT at 50.4 ft

RCH

RCH

RCH

RCH

RCH

RCH

RCH

3669.5

3652.6

2.50 54%

2.50 86%

2.30 92%

3.10 89%

1.50 100%

3.90 98%

0.90 90%

Description: (Density, Color, Type, Moisture, Other)

R un

/S am p N

o. Length Recov.

feet

% Rec.

Sheet 2 of 2Date: October 2015Project Name: Bucks Lake Road, CA FLAP PLU CR411(1)

Boring Location: STA 364+40, 120 ft RT

Coordinates:

Drill: CME 55 Track

Field Logged By: C. Martinez

Revisions/Final By: C. Martinez

Depth Elevation

(feet)

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

CENTRAL FEDERAL LANDS HIGHWAY DIVISION

BORING LOG

Driller: Taber Drilling G ra ph ic L og

RQD

SPT

Blows per 6 in

Boring No. B-1

Type of Boring: Auger/Core

Casing Used: HQ3

Boring Began: 10/6/15

Ground Elev: 3703.0 ft

Water Depth:

Date:

Time:

Size: 2.4"

Completed: 10/6/15

Weather: Sunny

U .S

.C .S

B O

R

IN

G L

O G

B U

C K

S L

A K

E .G

P J

S W

IF

T

TR

A

IL

.G

P J

/7

0.0 - 11.6 ft PHYLLITE, Gray to brown AR 1 Phyllite, gray brown. Drove casing to 5'.

RCH 1 Rec. 0.7 ft of phyllite, gray brown, highly weathered, very weak (R1), folliated, moderate angle, very close to close, smooth to rough. No water return.

RCH 2 Rec. 2.9 ft of phyllite, gray brown, highly weathered, very weak (R1), folliated, very close and quartzite, dark gray, moderately to…