GR01-15_Dene_Tene_Pedrestrain_Bridge_Foundation_Report__31March2015_.pdf

Dene’ Tene’ Pedestrian Bridge

AK TTP CHIC 2013(1)

Geotechnical Report No. 01-15

Dene’ Tene’ Pedestrian Path

Eska Creek Pedestrian Bridge

FINAL FOUNDATION REPORT

Chickaloon Village Traditional Council

Matanuska-Susitna Borough, Alaska

March 2015

Dene’ Tene’ Pedestrian Bridge

Geotechnical Report GR01-15 Page i

Contents

1. INTRODUCTION

1.1 Project Location

1.2 Scope of Project

2. SITE CHARACTERIZATION

2.1 Topography and Site Description

2.2 Average Temperatures and Precipitation

3. SUBSURFACE CONDITIONS

3.1 Site Geology

3.2 Regional Seismicity

3.3 Subsurface Investigation

3.4 Groundwater

4. NATURAL HAZARDS

4.1 Stream Scour

4.2 Seismic Hazard

4.2.1 Seismic Site Class

4.2.2 AASHTO Seismic Design Parameters

4.2.3 Deaggregation

4.2.4 Next Generation Attenuation Models Analysis

4.3 Liquefaction

4.3.1 Liquefaction Potential

4.3.2 Liquefaction Analysis Considerations

5. FOUNDATION RECOMMENDATIONS

5.1 Foundation Considerations

5.2 Bridge Layout and Loads

5.3 GRS-IBS Abutment

5.3.1 Design Parameters

5.3.2 Design

5.4 Construction Considerations

5.4.1 Dewatering

5.4.2 Additional Resources

6. EMBANKMENT and PATHWAY SUBSTRUCTURE

7. REFERENCES

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Appendices

APPENDIX A

Site Pictures

APPENDIX B

1996 Boring and Penetrometer Test Sounding Locations Map relative to Dene’ Tene’ Pedestrian Bridge

APPENDIX C

AKDOT& PF Foundation Report for Eska Creek Bridge

APPENDIX D

Liquefaction Analyses

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Figure 1: Project Vicinity Map

Project Vicinity

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Figure 2: Project Location Map

Project Location

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1. INTRODUCTION

This report provides general geologic site conditions, analysis, and final foundation recommendations for the proposed Dene’ Tene’ Pedestrian Bridge across Eska Creek.

1.1 Project Location

The project site is in Sutton, Matanuska-Susitna Borough, Alaska. The proposed pedestrian bridge is located 25 feet north of the existing Glenn Highway Bridge across Eska Creek. The project location is shown in Figures 1 and 2. The location of the proposed pedestrian bridge relative to the existing highway bridge is shown in Appendix A, Figure A-3.

1.2 Scope of Project

This bridge will connect a pedestrian path from the Chickaloon Village Traditional Building in Sutton to an existing trail system located on the opposite side of Eska Creek.

The proposed Eska Creek Pedestrian Bridge has a total length of 125 feet and a width of 16 feet. The proposed use of this bridge includes pedestrians, bicyclists, ATVs and snowmobiles. Currently the only means to cross the creek are to either ford the creek or use the highway bridge, which does not have a sidewalk or pedestrian path.

2. SITE CHARACTERIZATION

2.1 Topography and Site Description

The project lies within the Matanuska River Valley. Eska Creek is a tributary to the Matanuska River whose confluence is approximately three-fourth of a mile southwesterly from the project site. The terrain at the proposed bridge location is generally level. The creek banks are vegetated with willows and deciduous trees. The material in the creek bed consisted of sand to boulder-sized material. During a site visit in September 2013 the maximum depth of water at the proposed pedestrian bridge location was about 3 feet.

2.2 Average Temperatures and Precipitation

Table 1 shows the average maximum and minimum temperatures, average monthly precipitation, and average monthly snowfall data for the period of 1978 to 2011 (Western Region Climate Center, 2015).

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Table 1: Average Temperature, Precipitation, and Snowfall for Sutton, AK.

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3. SUBSURFACE CONDITIONS

3.1 Site Geology

Based on Geologic Map of the Cook Inlet Region, Alaska (2012), the area surrounding the project is described as Holocene-age alluvium deposits that consist primarily of gravel and sand within well-bedded and sorted beds. The thickness of this deposit ranges from a few meters in very low terraces to 10 meters within low to higher terraces. Other geologic units mapped near the project include poorly-sorted to well-sorted silt to boulders in alluvial fans that may grade into colluvial deposits, glaciolacustuarine deposits, or talus.

3.2 Regional Seismicity

The USGS Earthquake Hazards Program website (http://earthquake.usgs.gov/) was used to locate nearby faults. The Castle Mountain Fault, approximately 7 miles from the bridge site, is the closest active fault. The Maximum Credible Earthquake (MCE) for the Castle Mountain Fault is magnitude 7.18. Table 2 provides a list of regional faults, including the approximate distance and direction, orientation relative to the project, slip rate, slip sense, dip direction, and age of each fault.

Table 2: Regional Faults

Name Approx. Distance &

Direction (from project)

Slip Rate Slip Sense

Dip Direction

Age (Years)

Castle Mountain Fault (Talkeetna West Section)

7 miles North & West <0.2 mm/yr. SS Vertical, north <1,600,000

Castle Mountain Fault (Susitna Section) 12 miles West 1 - 5 mm/yr. SS Vertical, north <15,000

Denali Fault (West Muldrow-Alsek Section)

125 miles North >5 mm/yr. SS Vertical <15,000

Denali Fault (Central Muldrow-Alsek Section)

300 miles East 1 - 5 mm/yr. SS Vertical <15,000

Susitna Glacier Fault 125 miles Northwest 1 - 5 mm/yr. T Northwest <150

Totschunda Fault 225 miles East >5 mm/yr. SS Vertical <150

NOTE: SS – Strike Slip, T – Thrust

3.3 Subsurface Investigation

http://earthquake.usgs.gov/

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The Alaska DOT&PF drilled two borings and conducted two penetrometer test soundings for the construction of a new bridge (AKDOT Bridge No. 542) across Eska Creek site in July-August 1996. The report Foundation Report, Glenn Highway: MP 55-61, Moose Creek to Sutton, Eska Creek, Bridge No. 542, (Barber, 1997) contains information related to the 1996 subsurface investigation for the highway bridge. This report is contained in Appendix C. The approximate locations of the borings and penetrometer test soundings relative to the proposed pedestrian bridge are shown in Figure B-1 located Appendix B.

The boring logs indicate the collar elevation of boring 96-1 is 140.3 meters (460.3 feet) and boring 92-2 is 141.2 meters (463.25 feet). The collar elevations of the penetrometer test soundings were between the two boring collar elevations. These elevations plot 5 to 10 feet below the ground surface using the current project datum. It is suspected that different survey geoids were applied at the AKDOT control point at the time the Dene Tene project was surveyed. The report mentions the flowing stream was generally less than 2 meters (6.5 feet) below the collar elevations (Barber, 1997). Therefore, for design analysis the 1996 collar elevations are changed in respect to the current stream elevation of 467 feet. The collar elevations of boring 96-1 is assumed at 470.5 feet and boring 96-2 is assumed at 473.5 feet.

The borings were drilled using NW (3.5-inch O.D) casing and BW (2.1-inch) rotary drilling tools. In situ tests included standard penetration test (SPT) and penetrometer test soundings that consisted of driving a 2.5-inch diameter flush coupled blunt-tipped steel rod with a 342-pound automatic hammer. The boring logs are provided in the 1997 report (Barber, 1997) contained in Appendix C.

The general subsurface profile consists of alternating layers of silty sandy gravel, gravelly sand, and cobbles and boulders in a matrix of sandy gravel. SPT N-values ranged from 6 to greater than 100 blows per foot (bpf). Coarse gravel, cobble, and boulders can misleadingly increase SPT N-values. The SPT N-values reported in the borings were evaluated by comparing them to the NW casing blow count for that boring.

Throughout the test holes the higher N-values correlated to higher casing blow counts and lower N-values correlated to lower casing blow counts at the same depth. We also compared the SPT N-values to the adjacent penetrometers and noted similar trends in penetration resistance (blow counts) between Pent 96-1 and Boring 96-1 and between Pent 96-2 and Boring 96-2. From this comparison, we concluded that the SPT N-values shown were generally representative of the layers and could be used as input into a liquefaction analysis.

Table 3 shows a summary of borings 96-1 and 96-2 standard penetration test (SPT) N-values and laboratory test results. Based on the subsurface profile at the bridge site, the weighted average SPT N-values for the top 100 feet of subsurface materials was determined to be 48 blows per foot in Boring 96-1 and 20 blows per foot in Boring 96-2.

Plasticity Index (PI) values range between 6 and 21.

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Table 3: Summary of Borings 96-1 and 96-2 N-Values and Laboratory Test Results (project corrected depths)

3.4 Groundwater

Groundwater was not encountered in the two borings. After the casing was removed, Boring 96-1 remained dry and open to an elevation of 437 feet and Boring 96-2 to an elevation of 444.5 feet (project datum 447 feet and 454.5 feet, respectively), even though the creek is less than 25 feet from the boring locations and the water level in the creek was at an elevation of 457 feet (project datum 467 feet).

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Stream flow and ground water will vary with seasonal precipitation and snowmelt. The cohesionless soils, indicated by the boring logs, will have a tendency to cave in unsupported excavations below the groundwater table.

The WFLHD Hydraulics Report (Frye, 2014) provides the anticipated flow rate, existing water surface elevation, and proposed water surface elevation. Table 4 is the table from the report.

Table 4: Eska Creek existing and proposed surface water elevations (Frye, 2014).

Recurrence Interval

2-year 10-year 25-year 50-year 100-year 500-year Existing Water Surface Elevation

(feet)

467.49

468.08

468.35

468.54

468.72

469.14

Proposed Water Surface Elevation

467.40

468.04

468.33

468.54

468.74

469.20

Difference in Water Surface Elevation (feet)

0.09

0.04

0.02

0.00

0.02

0.06

Clearance

5.60

4.96

4.67

4.46

4.26

3.80

Existing Flow Velocity (ft/sec)

3.89

4.88

5.40

5.76

6.10

6.97

Proposed Flow Velocity (ft/sec)

4.27

5.03

5.43

5.74

6.03

6.82

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4. NATURAL HAZARDS

4.1 Stream Scour

Based on an email dated March 24, 2014, Megan Frye, WFLHD Hydraulic Engineer, indicated scour elevation at the project is 3 feet below the thalweg or at an elevation of 461 feet (project datum).

4.2 Seismic Hazard

The American Association of State Highway and Transportation Officials (AASHTO) criteria for seismic design of ordinary bridges, allows for damage to occur when the structure is subjected to 1000-year strong ground motion, but does not allow for collapse of one or more spans and loss of life. Bridges may suffer damage that requires repair or partial replacement. AASHTO, however, requires bridges to withstand small, more frequent earthquakes without damage.

The procedures outlined in Section 3.10 of the AASHTO LRFD Bridge Design Manual 7th Edition (2014) were followed to characterize the seismic hazard. These procedures use a design earthquake with a return period of 1000 years, or a 7 percent probability of exceedance (PE) in 75 years. The locations of nearby faults are discussed in Section 3.2, Regional Seismicity.

4.2.1 Seismic Site Class

According to the site class definitions specified in Table 3.10.3.1-1 of ASSHTO-LRFD Bridge Design Specifications 7th Edition, 2014 (AASHTO-LRFD). This site falls into Site Class D, defined as stiff soil with average Standard Penetration Test (SPT) blow count for the upper 100 feet of the soil profile between 15 and 50 blows per foot, moisture content less than 40%, and a PI value less than 20.

Table 2 shows a summary of borings 96-1 and 96-2 standard penetration test (SPT) N-values and laboratory test results. Based on the subsurface profile at the bridge site, the weighted average SPT N-values for the top 100 feet of subsurface materials was determined to be 48 blows per foot in Boring 96-1 and 20 blows per foot in Boring 96-2.

Plasticity Index (PI) values range between 6 and 21.

4.2.2 AASHTO Seismic Design Parameters

The Dene’ Tene’ Bridge site is located at 61.710594 degrees latitude and -148.899231 degrees longitude (NAD83). The AASHTO Seismic Design Parameters Software (version 2.10) was used to determine the following ground motion parameters for the site.

Horizontal peak ground acceleration (PGA), short-period spectral acceleration (Ss), and long-period spectral acceleration (S1), for the referenced AASHTO weak rock site class (Site Class B) and a 1000-year return period (7 percent probability of exceedance in 75 years).

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The spectral accelerations were scaled to the referenced AASHTO Site Class D using the site factors recommended in Tables 3.10.3.2-1, 2, and 3 in AASHTO manual (2014). The values in Table 5 were used to develop the 5-percent-damped-design response spectrum shown in Figure 3 below.

Table 5. Summary of Seismic Parameters (7% PE in 75 years).

Site Class (by Soil Type and Penetration Resistance in Top 100 Feet of Profile) D

Horizontal Peak Ground Acceleration on Site Class B Rock (PGA) 0.571

Horizontal Response Spectral Acceleration at Period of 0.2 sec on Site Class B Rock (Ss) 1.294

Horizontal Response Spectral Acceleration at Period of 1.0 sec on Site Class B Rock (S1) 0.503

Site Factor at Zero-Period Acceleration Spectrum (Fpga) 1.0

Site Factor at Short Period Acceleration Spectrum (Fa) 1.0

Site Factor at Long-Term Period Acceleration Spectrum (Fv) 1.5

Scaled Peak Ground Acceleration for Site Class Listed (As) 0.571

Scaled Horizontal Response Spectral Acceleration at Period of 0.2 sec for Site Class Listed (SDS) 1.294

Scaled Horizontal Response Spectral Acceleration at Period of 1.0 sec for Site Class Listed (SD1) 0.755

AASHTO Seismic Zone 4

Figure 3: 5% Damped Design Response Spectrum

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

El as tic S ei sm ic C oe ffi ci en t, C sm

Period, T (sec)

5% DAMPED DESIGN RESPONSE SPECTRUM

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4.2.3 Deaggregation

A seismic hazard deaggregation was performed for this project to determine the nearest sources contributing significantly to the seismic hazard at the bridge. The USGS 1996 Interactive Deaggregation website (https://geohazards.usgs.gov/deaggint/1996/) was used to determine the seismic hazard for a 5% in 50 year exceedance probability (975-year return period). The Deaggregation Hazard Data shows the principal sources of seismic hazard relative to the project site. Table 6 shows a summary of principle sources contributing to the seismic hazard.

Table 6. Summary of Deaggregation Hazard Data for 975-Year Return Period.

Principal Sources % Contribution

Distance, R

(miles)

Moment Magnitude, M PGA Shallow Random Sources M5-M7.3 44.23 5.5 6.18

AK 37.2-mile deep seismicity 23.71 50 5.82

Castle Mountain Fault 10.21 7.7 7.18

1.0 Second S1 M9.2 Megathrust 11.8 51 9.2

1964-Zone M9.2 Megathrust 16.56 40 9.2

Shallow Random Sources M5-M7.3 35.27 7.76 6.64

Castle Mountain Fault 13.32 7.95 7.2

0.2 Second Ss Shallow Random Sources M5-M7.3 46.65 6.3 6.25

AK 37.2-mile deep seismicity 15.41 48 5.98

Castle Mountain Fault 11.27 7.3 7.15

4.2.4 Next Generation Attenuation Models Analysis

Next Generation Attenuation (NGA) models were used to estimate average peak ground acceleration for the specific faults that contribute significantly to the seismic hazard to be used as input into a liquefaction analysis. The mean PGA of five NGA relationships was determined and adjusted for the Site Class D soil conditions to determine the PGA at the ground surface. The Castle Mountain Fault was chosen for this attenuation analysis due to the close proximity to the project and the elevated moment magnitude value. Based on the five attenuation models, the PGA is 0.306g.

Due to the proximity and large moment magnitude value of the Alaska- Aleutian Megathrust Fault, a second attenuation analysis conducted for the Alaska-Aleutian Megathrust Fault determined the site specific PGA is 0.321g. The Youngs et al (1997) attenuation model, developed for subduction zone earthquakes, was used to determine the PGA for this fault.

https://geohazards.usgs.gov/deaggint/1996/

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4.3 Liquefaction

Recently deposited and relatively loose natural soils and un-compacted or poorly compacted fill soils are susceptible to liquefaction. Submerged loose sand and silty sands are particularly susceptible to liquefaction. Loose silts and gravels may also have a potential for liquefaction. Dense natural, well-compacted fills and cohesive soils are known to have a relatively low susceptibility to liquefaction.

4.3.1 Liquefaction Potential

Initial screening of site conditions for the potential for liquefaction was conducted to determine if a more detailed evaluation of liquefaction would be necessary. An evaluation for the potential for, and consequences of, liquefaction in soils near the surface was made in accordance with the following criteria (FHWA, 2011):

• Ground water level is within 50 feet of the ground surface, and soils that are susceptible to liquefaction are below the groundwater table.

• Seismic Hazard Level of the bridge, which depend on the value of Site Class-adjusted peak ground acceleration.

• Geologic age and depositional environment are indicators of liquefiable materials.

Relatively young deposits (Holocene <11,000 years) deposited in potentially loose, uncompacted environments are susceptible to liquefaction.

• Clayey soils with low sensitivity have a potential for liquefaction if one or more of the following criteria are met:

• Clay content (grain size < 0.005 mm) less than 15 percent;

• Liquid limit less than 35 percent; or,

• Natural water content greater than 90 percent of the liquid limit.

• Clayey soils with high sensitivity should not be screened out. Sensitive clays possess all of the following properties:

• Liquid limit less than 40 percent.

• Water content greater than 0.9 times the liquid limit

• Liquidity index greater than 0.6

• (N1)60 less than five or normalized cone penetration resistance qc1, less than 20 ksf.

• Low plasticity silts and sands have a potential for liquefaction if:

• Minimum corrected Standard Penetration Test resistance, (N1)60 values are less than 25 blows per foot,

• Corrected cone penetration test tip resistance qc1, is less than 150 ksf with a sufficient number of tests,

• The normalized shear wave velocity, Vs1, is less than 660 ft./sec., or

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• Or a geologic unit is present at the site that has been observed to liquefy in past earthquakes

4.3.2 Liquefaction Analysis Considerations

The boring logs suggest the subsurface is can be generally characterized for design purposes as three horizontal strata. Table 7 shows the idealized stratigraphy of the project site and initial screening criteria used to assess susceptibility to liquefaction. The soils in Layer 1 are predominantly low plasticity sandy silt located above the groundwater table. Layer 2 exhibits several discontinuous strata of variable-thickness consisting of loose to dense silt, sandy silt, gravelly sand, slightly clayey sandy gravel, and sandy gravel. The gravel layers are relatively pervious and can often rapidly dissipate cyclically generated pore pressures and prevent liquefaction (Seed et al, 1997).

Layer 3 is characterized as dense to very dense silty sandy gravel with cobbles and boulders. This layer is referred to as Pleistocene-aged glaciofluvial deposits (Barber, 1997).

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Table 7: Soil Characterization for Liquefaction Potential

Liquefaction analyses are contained in Appendix D. Plates D-1 and D-3 shows existing conditions at Borings 96-1 and 96-2, and Plates D-2 and D-4 shows after construction conditions. The liquefaction analysis uses Tokimatsu and Seed settlement model.

Based on the considerations listed above our interpretation is that the liquefaction hazard at this site is low because only discrete pockets of soil across the site are interpreted to be susceptible to liquefaction. Therefore, we believe that flow liquefaction or lateral spreading would not occur if a seismic event does trigger liquefaction in discrete pockets of soil at this site. We interpret that liquefaction in these discrete pockets would result in settlement. We estimate that the amount of total and differential settlement at the site would be less than 5 inches. WFLHD Structural Engineer has accounted for this possible magnitude of differential settlement in the bridge design.

When considering seismic hazard it is important to consider the tolerable level of risk relative to the perceived hazard. The proposed pedestrian bridge is not critical infrastructure that is necessary to remain in service after the design seismic event. The risk associated with the seismic hazard is that during a large earthquake the bridge suffers

Geotechnical Report GR01-15 Page 13 March 2015 damage due to settlement and partial or complete replacement may be required. Another project risk that must be considered is the additional costs that would be associated with deep foundation alternatives and/or ground improvement. Those additional costs may delay delivery of this project or even result in this project being cancelled if the costs are outside currently programmed values. In that instance pedestrians would have to continue fording the creek or use the highway bridge to cross the creek.

5. FOUNDATION RECOMMENDATIONS

5.1 Foundation Considerations

Spread footings, GRS-IBS and driven piles are the foundation types that were considered for this site.

A conventional concrete spread footing foundation was considered but not chosen because a GRS-IBS foundation system would be more a more flexible system have faster construction, and would be more cost effective. GRS-IBS technology consists of closely spaced layers of geosynthetic reinforcement and compacted granular fill material to create a reinforced soil foundation, abutment, and integrated approach for the bridge.

The application of GRS-IBS has several advantages. The system is easy to design and cost effective to construct. It can be quickly built in variable weather conditions with readily available labor, materials, and equipment and can easily be modified in the field.

GRS-IBS is relatively more flexible compared to other foundation alternatives during seismic events. The GRS-IBS system integrates the superstructure into the abutment and approach embankment and thereby eliminates the bump at the end of the bridge that typically occurs with deep foundations.

According to the 2004 As-Built plans for the Glenn Highway Bridge crossing Eska Creek the bridge foundations consists of 12, HP 14x117, piles driven 138 feet. The cost of driven piles would be high compared to the GRS-IBS option. The cobbles and boulders encountered in the borings could create difficult driving conditions, possible leading to pile damage. In addition, piles are more likely to run in granular deposits. These site conditions increase the risk of costly contract modifications for driven pile foundations on this project.

Based on these considerations GRS-IBS foundations are the recommended foundation type for this project.

5.2 Bridge Layout and Loads

The single span, pre-fabricated steel bridge is 127 feet long and 14 feet wide. The bridge is supported with a concrete abutment seat 19 feet long and 6.3 feet wide.

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WFLHD Structural Engineer, Benn Oltmann, provided the following bridge foundation loads per abutment in April 2014:

• Design vehicle - H10

• Unfactored dead loads:

o Steel Truss – 30.0 kip o Concrete deck – 75 kip o Concrete abutment slab – 45 kip

• Unfactored pedestrian live load = 85.0 kip

5.3 GRS-IBS Abutment

5.3.1 Design Parameters

The height of from the top of Reinforced Soil Foundation (RSF) to the bottom of the abutment slab is 10.9 feet for Abutment 1 and 9.7 feet for Abutment 2. The abutment width at the face is 26 feet and each wing wall is 15 feet long and constructed 90 degrees from the abutment face. The minimum distance from the back of the guardrail post to the back of the CMU block facing is 4 feet. Table 8 shows the resistance and load factors used in design.

Table 8: GRS-IBS Design Load and Resistance Factors Load Factors

Horizontal Earth Pressure γEH MAX 1.50 γEH MIN 0.90

Earth Surcharge γES MAX 1.50 γES MIN 0.75

Vertical Earth Pressure γEV MAX 1.35 γEV MIN 1.00

Components γDC MAX 1.25 γDC MIN 0.90

Live Surcharge γLS 1.75 Live Load γLL 1.75 Earthquake γEQ 1.00

Resistance Factors Sliding Φτ 1.00 Bearing Resistance Φbc 0.65 Vertical Capacity Φcap 0.45 Reinforcement Strength Φref 0.90

Table 9 shows the soil parameters used in GRS-IBS design.

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Table 9: Soil parameter used in GRS-IBS design

Foundation Soil Parameters

Properties Symbol Units Foundation

Soil Retained

Soil Reinforced

Soil1

RSF

Soil1

Unit Weight γf , γb , γr , γrsf pcf 120 125 125 125

Friction Angle φf , φb , φr , φrsf deg 32 32 38 38

Cohesion cf , cb , cr , crsf pcf 0 0 0 0

Active Coefficient Kaf , Kab , Kar - 0.307 0.307 0.147 -

Passive Coefficient Paf , Pab, Kar - 3.255 3.255 6.786 -

Coefficient of Sliding μf , μb , μr , μrsf = 2/3* tan(φf , φb , φr , φrsf)

- 0.417 0.417 0.740 0.600

Maximum Particle Size dmax in. - - 0.5 0.5

Note: 1 Open-graded

Based on the reported superstructure unfactored loads, the applied pressure on each GRS abutment is approximately 1950 psf and the factored applied pressure on each GRS abutment is approximately 2790 psf.

5.3.2 Design

A 2.5-foot thick reinforced soil foundation (RSF) under the GRS is recommended. The RSF extends 15 feet behind from the abutment facing and 2.5 feet in front of the abutment and wing wall facing. Grade, level and compact the backfill prior to encapsulating the RSF. Overlap all geosynthetic seams 3 feet and oriented to prevent running water from penetrating the layers of reinforcement. Encapsulate the RSF with geotextile reinforcement placed perpendicular to the abutment face to protect from possible erosion. Size the geotextile to fully enclose the RSF on the face and wing wall’s sides. Ensure the corners of the RSF are tightly wrapped and soil is not exposed.

Compact the RSF backfill in 6-inch lifts.

Typical CMUs for the project will measure 7-5/8” x 7-5/8” x 15-5/8.” (Nominally, 8” high x 8” wide x 16” long.). The CMU must conform to ASTM C90, a minimum net area compressive strength of 4,000 psi based on ASTM C140, and maximum absorption of 5 percent, also based on ASTM C140. The three types of CMUs required for this project include 1) solid, colored CMU, 2) solid, non-colored CMU, and 3) hollow, non-colored CMU.

Colored solid CMU blocks extend from the top of the RSF to 2 feet below top of riprap (elevation 468 feet). Only uncolored solid CMU blocks are acceptable above elevation

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468 feet. The top three rows consist of hollow CMU blocks, which are pinned in with rebar and concrete. Clearance space between the top of the CMU block face and the bottom of the superstructure should be a minimum of 3 inches. Setback the bottom front of the abutment slab 16 inches from the CMU block face.

The minimum base length of the reinforcement (not including the reinforcement width between the CMU block) is 15 feet within the GRS. Vertical spacing of the reinforcement in the GRS zone should not exceed 8 inches. Bearing bed zone reinforcement consists of five layers with minimum length of 15 feet as measured from the CMU face and vertical spacing of 8 inches. Within the bearing bed zone a secondary reinforcement is place equal distance between the primary reinforcements with minimum length of 9 feet measured from the back of the facing blocks.

The integrated approach zone consists of six reinforcement layers with a vertical spacing of 10 inches and 4-foot wrap. Note that the last wrapped tail reinforcement in the integrated approach extends 12.5 feet from the end of the bridge.

The recommended backfill for the RSF, GRS, bearing bed, and bearing seat zones is open-graded crushed gravel. Recommended open-graded backfill material consists of clean, crushed angular (not rounded) stone. The minimum maximum grain size to efficiently achieve compaction behind the abutment wall face is 0.5 inches. An example of a typical open-graded abutment backfill is shown in Table 10. The amount of fines passing the No. 200 sieve should be as close to 0 percent as possible and no more than 5 percent.

Figure 10:GRS abutment open-graded backfill (AASHTO No. 89)

5.4 Construction Considerations

5.4.1 Dewatering

The elevation of the bottom of the RSF is 458.5 feet (project datum). This elevation is well below the creek surface elevation. Table 4 shows the existing and proposed flow volumes and the elevation changes. Even though water was not encountered in Borings

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96-1 and 96-2 above an elevation of 445 feet; there is a risk the RSF excavations will require some method of dewatering. If the excavation is inundated with water, dewatering is required so the backfill can be placed and compacted in the dry. Extensive dewatering systems including sump and well points may be required to control groundwater infiltration.

The soils within the excavations are anticipated to consist of gravel with sand and silty clay (GM-GC), silty clay with sand (CL-ML), and silty sand (SM). The maximum allowable temporary slope ratio for excavations less than 20 feet without groundwater infiltration is 1V:1.5 H. The cohesionless soils encountered in the borings will cave-in if left unsupported when excavations extend below the groundwater table. Temporary shoring is anticipated between the pedestrian bridge and the highway bridge for abutment construction.

Careful attention should be given to the installation of the first row of blocks. Since all other courses of block are built off the first row, it is essential to ensure that the bottom row is level and even for construction.

5.4.2 Additional Resources

FHWA provides a GRS-IBS construction video located at the following website:

http://www.fhwa.dot.gov/everydaycounts/technology/grs_ibs/multimedia.cfm

This construction video also can be viewed on the FHWA's YouTube channel at:

http://www.youtube.com/user/USDOTFHWA#p/a/u/0/w_5WFoAdoUw

The construction video follows the guidance outlined in the GRS-IBS Implementation Guide, FHWA-HRT-11-026, dated January 2011, which is available at the following website:

http://www.fhwa.dot.gov/publications/research/infrastructure/structures/11026/index.cfm

6. EMBANKMENT and PATHWAY SUBSTRUCTURE

The material from the GRS-IBS excavation will likely have over-optimum moisture content for the pathway embankment construction. The maximum fill slope ratio for onsite material from excavation and imported material meeting the specifications for unclassified borrow is 1V:2H.

Pavement design recommendations are provided by the Western Federal Lands Highway Division (WFLHD) Materials Section memorandum Preliminary Structural Pavement Recommendations for Dene’ Tene’ Pedestrian Path dated November 25, 2013. The memorandum recommends 12 inches of Select Borrow placed directly under the pavement structure.

http://www.fhwa.dot.gov/everydaycounts/technology/grs_ibs/multimedia.cfm http://wwwcf.fhwa.dot.gov/exit.cfm?link=http://www.youtube.com/user/USDOTFHWA#p/a/u/0/w_5WFoAdoUw http://www.fhwa.dot.gov/publications/research/infrastructure/structures/11026/index.cfm

Geotechnical Report GR01-15 Page 19

7. REFERENCES

AASHTO, 2014, AASHTO LRFD Bridge Design Specifications, Seventh Edition, American Association of State Highway and Transportation Officials, Washington, D.C.

Adams, M., et al, (2012) Geosynthetic Reinforced Soil Integrated Bridge System, Interim Implementation Guide, Report No. FHWA-HRT-11-026, Federal Highway Administration, 169p.

Alaska Division of Geological & Geophysical Surveys, Quaternary Faults and Folds, Interactive Map, Alaska Department of Natural Resources, http://maps.dggs.alaska.gov/qff/#17900000:9100000:3, Accessed 28Jan2014..

Barber, T. (1997) Foundation Report, Glenn Highway: MP 55-61, Moose Creek to Sutton, Eska Creek, Bridge No. 542, Project No. IM-OA1-5(9), State Project No. 52495, Central Region, Alaska Department of Transportation.

Federal Highway Administration Lands Highway, 2006, Technical Guidance Manual (TGM), A Geotechnical Supplement to the FLH Project Development and Design Manual.

Frye, M. (2014) Eska Creek Bridge TS&L Hydraulics Report, Federal Highway Administration, Western Federal Lands Highway Division.

Morehouse, D. (2014a) Geotechnical Memorandum GM05-14, Preliminary Foundation Recommendations, Dene Tene Path, Eska Creek Bridge, AK TTP CHIC 2013(1), Federal Highway Administration, Western Federal Lands Highway Division.

Morehouse, D. (2014b) Geotechnical Memorandum GM15-14, Liquefaction Analysis, Dene Tene Path, Eska Creek Bridge, AK TTP CHIC 2013(1), Federal Highway Administration, Western Federal Lands Highway Division.

Seed, R. et al (2003) Recent Advances in Soil Liquefaction Engineering: a Unified and Consistent Framework, Earthquake Engineering Research Center, College of Engineering, University of California, Berkeley.

Western Regional Climate Center, Cooperative Climatological Data Summaries, Sutton 2 E, Alaska (508915), http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ak8915, accessed 6Jan2015.

Wilson, F.H., (2012) Geologic Map of the Cook Inlet Region, Alaska, USGS Scientific Investigations Map 3153, 1:250,000-scale quadrangles.

http://maps.dggs.alaska.gov/qff/#17900000:9100000:3 http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ak8915

Geotechnical Report GR01-15

APPENDIX A

Site Pictures

Geotechnical Report GR01-15 Page A1 February 2015

Picture A1: Looking north, upstream, from under the highway bridge

Picture A2: Approximate bridge location across Eska Creek

Boring Locations Map

Boring 96-1

Pent 96-1 Boring 96-2

Pent 96-2

Glenn Highway Bridge over Eska Creek

FIGURE B-1

1996 Boring and Penetrometer Test Sounding Locations

(Approximate)

AKDOT& PF Foundation Report for Eska Creek Bridge

FOUNDATION REPORT

GLENN HIGHWAY: MP 55-61, MOOSE CREEK TO SUTTON

ESKA CREEK

BRIDGE NO. 542

PROJECT NO. IM-OA 1-5(9)

STATE PROJECT NO. 52495

CENTRAL REGION

SEPTEMBER 1997

APPROVED BY

AND

SUBMITTED BY

Prepared by

Barter, P.E.

aterials Engineer

Dan R. Pavey Chief Geologist

TeffYBber Foundation Geologist

Alaska Department of Transportation and Public Facilities Engineering and Operations

Headquarters Materials Section Anchorage, Alaska

TABLE OF CONTENTS

LOCATION MAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

INTRODUCTION

Purpose and Scope of Work

Climatological Data

METHOD OF EXPLORATION

LABORATORY TESTING

GENERAL SITE CONDITIONS

Surface

Subsurface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 thru 5

REFERENCES

APPENDIX A: PHOTOGRAPHS . . . . . . . . . . . . . . . . . . . . . . . . A-1 thru A-3

APPENDIX B: ALASKA DOT&PF TEXTURAL SOIL DESCRIPTIONS . . . . . . B-1

APPENDIX C: SUMMARY OF TEST DATA . . . . . . . . . . . . . . . . . C-1 thru C-3

APPENDIX D: TEST HOLE LOG AND LOCATION SHEETS . . . . . . . 1 thru 3

,.,j,,. }.l ... .. '

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a ii

STATE

DEPARTMENT OF ALASKA

A OF' TRAN

GLENN HI NO PUBLIC FAC:.':rORTATtON

GHWAY IES

MOOSE CREEK ~p 55 TO 61

IM-OAI -5~9TUTTON

ESKA c

BRIDGE NREEK 0 . 542

I

INTRODUCTION

Purpose and Scope of Work

The Department of Transportation and Public Facilities (DOT &PF) plans the construction of a new bridge at Eska Creek to replace the existing bridge at

Milepost 60.9 of the Glenn Highway near Sutton, Alaska. According to the preliminary plan, the structure will consist of a single span, 37.4 meter long bridge constructed of prestressed concrete bulb-tee girders. At the request of the Design

Project Manager, the DOT&PF Engineering Geology Branch conducted a foundation investigation at the proposed site in July, 1996, under the field supervision of K. T.

Hemenway, Engineering Geologist using DOT&PF personnel and equipment.

The purpose of the exploration was to:

1. Develop a soil profile for use in design.

2. Assess the suitability of the site for the proposed structure.

3. Support selection of an adequate and economic foundation design.

4. Anticipate and mitigate problems that could arise during construction.

This report describes the methods of exploration, sampling and field testing procedures, and general site conditions at the time of exploration.

CLIMATOLOGICAL DATA

Climatological data for the project area is taken from the Environmental Atlas .Q.{

Alaska. University of Alaska, May 1984, by P. R. Johnson and C. W. Hartman. It indicates that the project site is located within the Transitional Climatic Zone of

Alaska. This zone is characterized by moderate day to night and annual temperature variations, precipitation, cloudiness and humidity. The following figures, taken from the above referenced publication and other sources, are approximate.

Mean annual precipitation, mm

Mean annual snowfall, mm

Mean annual temperature, degrees C

1.1

For current, site specific weather information, contact the National Oceanic and

Atmospheric (NOAA) at 6930 Sand Lake Road, Anchorage, Alaska 99502-2956 or phone (907) 266-5105.

METHOD OF EXPLORATION

The geotechnical field exploration consisted of a limited surface geologic examination of the site together with a subsurface study which included a total of_ two (2) test holes and two (2) penetrometer test soundings at the bridge site. Test holes were drilled with a CME model 75 drill using NW (76 mm J.D. x 89 mm O.D.) casing and

BW (54 mm diameter) rotary drilling tools with water as the circulating medium. The casing was advanced with a 155 kg automatic hammer having a free fall of 750 mm.

Standard penetration tests were taken approximately every 0.75 to 1.5 meters in the test holes. The standard penetration test used a cathead-rope system with a standard split barrel sampler (35 mm J.D. x 50 mm O.D.) driven by a 63.5 kg hammer having a fr~e fall of 750 mm. The friction penetrometer test sounding consisted of driving a 64 mm diameter flush coupled blunt-tipped steel rod with a 155 kg CME automatic hammer having a free fall of 750 mm. Casing and penetrometer pullout tests were conducted to measure uplift resistance between the soil and the casing-rod. These tests were performed either immediately or up to 15 hours after driving using the drill's hydraulic feed/retract cylinder mechanism or a calibrated hydraulic jack. Graphic logs and test results are shown on the "Test Hole Logs and Locations" sheets included in this report as Appendix D. Selected photographs of the site taken during the exploration are included in the report (Appendix A).

LABORATORY TESTING

The samples were examined and visually classified by the field geologist. They were then sealed and transported to the Engineering Geology office at Headquarters

Materials in Anchorage. Soil samples received at the Headquarters Materials office were further examined by the Foundation Geologist and Soils Engineer. Selected samples were tested in the Central Region Materials Laboratory in Anchorage in accordance with Alaska DOT&PF, AASHTO and/or ASTM methods for a determination of the following properties:

1 . Particle size distribution

2. Moisture content

3. Classification

The results of the testing are listed in the Summary of Test Data sheets C-1 through

C-3 in Appendix C and the samples not tested are available for inspection at the

DOT&PF's Headquarters Materials Section office in Anchorage.

GENERAL SITE CONDITIONS

Surface

The proposed bridge site is located at Milepost 60.9 of the Glenn Highway which is within the lower Matanuska Valley near Sutton, Alaska (see location map ii).

Geomorphically the stream is classed as "flood plain" exhibiting surficial features of a mature valley drained by the Matanuska River.

The topography at the proposed site is gently sloping to level, well drained with open grass covered areas, trails, dirt roads, parking areas and scattered to dense stands of mature cottonwood trees and brush.

The head of Eska Creek is approximately 10.4 kilometers north of the proposed bridge site at the 1 525 meter level near Granite Peak in the Talkeetna Mountains. At the time of exploration the relatively small stream flowed clear, shallow and at a moderate flow rate over a streambed composed of gravel, cobbles and boulders. The channel is well defined with low, gentle to moderately sloped stream banks. Vegetation consisted of brush and grasses. Eska Creek is a small crooked tributary to the Matanuska River whose confluence is approximately 1.25 kilometers southwesterly from the project site.

Geologically, the general surface area consists of alluvial and glacial depositional landforms featuring active flood plains, outwash aprons, moraines, eskers and kames.

Underground telephone utilities are present within the limits of the proposed project area. At the northeast corner of the existing bridge there is a rusted road sander hopper placed for highway embankment protection. Also, an estimated 3 to 4 foot diameter· boulder is visible in the embankment fill at the northwest corner of the existing bridge. See photos in Appendix A.

Subsurface

Results of the subsurface exploration at the proposed bridge location indicate 11.2 to

12 meters of recent alluvium consisting of loose to very very dense, · moist stratified mixtures of sand, silt and gravel with cobbles and boulders overlie at least 19.2 meters of very very dense, glaciofluvial (Pleistocene aged) slightly silty to silty sandy gravel containing cobbles and boulders (See Test Hole Logs in Appendix D). Bedrock was not encountered to the depths drilled and sounded. In Test Hole 96-1 a 2.6 meter layer of coarse gravel with concentrated cobbles ~nd boulders exists between Elevation 132.5 and 129.9 meters.

Although the flowing stream water was generally less than 2 meters below the collar elevation of the test holes and the borings were located close to the creek itself, no groundwater was found in either test hole above Elevation 135.6 meters. After drilling, all casing was pulled from the ground and open dry holes were measured from 5.6 to

7.2 meters deep at Test Holes 96-2 and 96-1 respectively.

' ._,a, Stream flow and groundwater is anticipated to vary with seasonal precipitation and meltwater.

This project site is located in a shaded area with long cold winter months; so deep seasonal frost should be expected. Neither seasonal frost nor perennially frozen soil were found at the time of exploration.

The reader should consult the Test Hole Log and Location sheets in Appendix D of this report for a complete detailed description of each test hole and sounding at the proposed bridge site.

Special Conditions:

According to local DOT&PF maintenance personnel, Eska Creek "ices" or "glaciates" each winter resulting in ice building and aggrading up to the steel bridge girders.

Annual scheduled deicing or steam thawing for drainage is required at the existing bridge.

Prepared by:

-8;:~~ Engineering Geologist

REFERENCES

Hunt, R.E., Geotechnical Engineering Investigation Manual, McGraw-Hill Book Company, 983 p.

Johnson & Hartman, 1984, Environmental Atlas of Alaska, 2nd Ed. Revised: lnst. of Water Resources, Univ. of AK, Fairbanks.

Barnes, F.F., Geologic Map of Lower Matanuska Valley, Alaska, MAP 1-359, USGS, 1962. .

State of Alaska DOT&PF, Engineering Geology & Geotechnical Exploration Procedures Manual, May 1993.

Looking easterly across deck of existing bridge toward Sutton.

The drill is located at Test Hole 96-1.

Looking westerly toward the existing bridge.

Drill is located at Penetrometer 96-1.

Eska Creek Bridge No. 542

July, 1996

A-1

Looking southerly (downstream) toward existing bridge.

l ooking northerly (upstream) toward existing bridge site.

Eska Creek Bridge·No. 542

A-2

Looking easterly across upstream side of existing bridge toward drill at Test Hole 96-1.

Note large surplus sander hopper used as rip rap outlined in photo.

Enlarged photo of steel sander box placed at NE corner of existing bridge .

A one meter diameter boulder exists at the NW corner of existing bridge.

Eska Creek Bridge No. 542

A-3

ALASKA DOT&PF TEXTURAL SOIL DESCRIPTION

' ALASKA DEPARTMENT OF TRANSPORTATION TEXTURAL SOIL DESCRIPTION

REVISED: AUGUST 97

tmE.S; ) • I M.l SillS Willi A PIASIIC IIIOCX > 4

Sl W.l OE I[RI.I£0 • SLICIIll Y CIA 'lEY."

2) 5mOS AIIO CRAWlS Willi 7% IIIRU 121. SILT

NID/OR WY(0.075 mm) SIL'll BE 1£RI.I£0 "SUCIIILY Slltf OR 1r PIASIIC, (PI > 4) "SUCIIIlY CtA'lf( SAND OR GRAVEl.

f.-- LESS TIIAN 207. SAND 1,.

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SANOY GRAVELLY GRAVELLY SANOY

SILT SILT Sill Sill

COARSE -GRAINED SOILS

35% OR LESS Sll T / CLAY

I GRAVEL > SAND SAND 2 GRAVEL I

SILT/ClAY < 0.075 mm DIAMETER) R) . SAND 0.075 mm TO 2.0 mm OIAM[J[

GRAVEL 2.0 mm 10 75 mm OIAt.IElER ) ER) COBBLES 75 mm TO 305 nvn OIAMEJ

BOULDERS + 305 mm 01/lM[l[R)

20% OR MORE SANI> ... ~ 20% OR MORE GRAVEL I LESS ll~ 20% CRAVIl ~ I N ~ ~ N N ~ ('I ('I

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FINE -GRAINED SOILS

MORE THAN 35% SIL T/_CLAY

I

I PI s.. 1 0 I PI ~ 11 I

LESS TIWI 207. GRAVEL ___ .., f-oooll·-- LESS II~ 201. GRAVEL I 20X OR I.IOR£ GRAVEl --~ I-a:: ~

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SANOY GRAVELLY GRAVELLY GRAVELLY SANOY SANOY

SILT CLAY SillY SIINDY SILlY GRAVELLY SILlY SANOY SANOY GRAVELLY CRAVELLY

CLAY ClAY CLAY SillY SILlY ClAY ClAY CLAY ClAY CLAY ClAY

I ~.

SUMMARY OF TEST DATA

PRECONSTRUCTION SAMPLE SUMMARY

Project Name Glenn Hwy 57-67

Project No 50861 Sampled By . Hemenwa~ Structure Eska Creek Bridge - Station Offset (feet) Depth (feet) 6.1 - 6.9 m 7.6 - 8.2 m 10.7 - 11.4 m 12.2 - 12 . 6 m 15.2 - 15 . 8 Test Hole No. TH 96-1 TH 96-1 TH 96-1 TH 96-1 TH 96 - 1 Field No . 1-020 1-025 1-035 1-040 1-050 Date Sampled 01123196 07123196 01123196 01123196 07124196 Lab No. 96A-2413 96A-2414 96A-2415 96A-2416 96A-2417

3" 2" 100 100 1" 96 100 83

Percent 314" 91 86 72 112" 82 74 66

Passing 3/8 11 70 70 59 100 #4 55 58 48 95

Sieve #10 42 41 100 35 90 #40 20 17 99 18 80

Size #80 #200 8 . 2 6.8 75.0 10.0 58.5 .02mm

. 002mm

DOTTSD Sa Si Cl AASHTO Class A-6(13) FSV Class Liquid Limit 31 Plasti c Index 21 Moisture Content % 27 . 1 40 . 4 Organic Content % % Gravel 58 59 65 10 % Sand 34 34 25 25 31 % Silt & Clay 8 7 75 10 59 Max. Dry Density Opt. Moisture % Sp.G. Fine Degradation Value :

L.A. Abrasion Loss Sulfate Soundness I I I I I

Note: Gradation tests based on minus 75 mm material. AASHTO class may be inappropriate if organic content >5%.

The sampler used to take the above samples has an inside diameter of 35 mm, therefore soil particles with a diameter larger than 35 mm were not recovered in the sample. See test hole logs for a field description of the tested material.

c~ 1 m 18.3 - 18 . 7 m

TH 96-1

1-060 07124196 96A-2418

70 . 4

Project Name Glenn Hwy 57-67

Project No. 50861 Sampled By

Station Offset (feet) Depth (feet) 24.4 - 25 m Test Hole No. TH 96-1 Field No. 1-080 Date Sampled 07124196 Lab No. 96A-2419

3" 2" 100 1" 95

Percent 314" 83 112" 66

Passing 318" 60 #4 46

Sieve #10 34 #40 19

Size #80 #200 9.7 . 02mm

.002mm

DOTTSD

AASHTO Class FSV Class Liqui d Limit Plastic Index Moisture Content % Organic Content % % Gravel 66 % Sand 24 % Silt & Clay 1:0 Max. Dry Density Opt . Moisture % Sp.G . Fine Degradation Value L.A . Abrasion Loss Sulfate Soundness I

PRECONSTRUCTION SAMPLE SUMMARY

Hemenway Structure Eska Creek Bri dge

30.5 - 30.8 m 3.0 - 3.8 m 4.6 - 5.2 m 6.1 - 6.9 m

TH 96-1 TH 96-2 TH 96-2 TH 96-2

1-100 2-010 2-015 2-020 07125196 07126196 07126196 07129196 96A-2420 96A-2421 96A-2422 96A-2423

100 100 100 87

96 83 79 72 71 100 65 100 57 96 49 99 43 94 33 94 24 86 13 70

12.4 61.7 5.7 18.4

Sl Cl Sa Si S1 Cl Si Sa A-4(2) A-2-4(0)

28 27 7 6

16.4 18.5

57 6 67 6 31 32 27 76 12 62 6 18

I I /. I

Note: Gradation tests based on minus 75 mm material. AASHTO class may be inappropriate if organic content >5%.

The sampler used to take the above samples has an inside diameter of 35 mm, therefore soil particles with a diameter 1::troP.r th::m 1<:; mm were not recovered in the samnle. See test hole logs for a field description of the tested material.

C-2

9.1 - 9.4 m

TH 96-2

2-030A 07129196 96A-2424 so

9.1

Sl C1 Sa Gr1 A-2-4(0)

12.3 c so

"TEST HOLE LOCATIONS" AND "TEST HOLE LOGS"

Q t D o

PROPOSED

ESKA CREEK BRIDGE

ESKA CREEK BRIDGE

SCALE 1:100

I I

J.

'r .

L. \ I I I I I I I I I I I I I I I I I I I I I I

TOTAL STATE PROJ ECT DESIGNAnON YEAR

SHEETS

IM-OA1-5(91 1997 1 3

I I

~,;J \

TOWN OF

SUTTON

l

I n(

-~ ~~~ ....... ~(.q •• , .:ei'···~···.s+''• : ... ··.? ,, .::*:'49!!! · .• ~ ~···M~~-· ...... :: ..... ~ ~-··~···. ~ ~ ~··. Kellh . K~·;:

~~~·· CE 5126 /fS5

111 ~l~· D" ft."::f:l'ff ,,,, tJ i,;;;: .. ·:.:. ..... ~ --~

.,,· OTuttSS\~

TEST HOLE LOGS

AND LOCATIONS

GLENN HIGHWAY

MP 55 TO MP 61

MOOSE CREEK TO SUTrON

ESKA CREEK BRIDGE

State of Alaska DEPARTMENT of TRANSPORTATION and

PUBLIC FACILITIES

Juneau, Alaska

Bridge No: s42

Drawing. No: 1 j

ELEVATIONS

IN METERS,

10:1

PENETROMETER 96-1

STA. STA. IO•OB9, :1.:1 m RT. OF PROPOSED t 7123/96-7126196

1.5

3.0

4.5

6.0

7.5

9.0

10.5

12.0

13.5

15.0

16.5

18.0

19.5

"' :E 21.0 ii!:

:r::

:;: 22.:1

"' Cl

24.0

25.5

27.0

28.5

30.0

31.5

33.0

36.0

37.5

39.0

40.5

TOTAL

DEPTH 42.7 on-J"'-"L:lf-.Ll,._--r---..c;;;:'"'f"-----, 0 100 200 300

P 96-1 NOTES

AI DISCONTINUOUS DRMNG RECORD

I. 0-U.89 m 7123/96: I HOUR DRIVING TIME

2. 0.89-17.99…