B.08.03_EIE431_Geotech_Data_Report_AM04.pdf

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Consolidated Geotechnical Data Report F-35 Conventional Munitions Maintenance Facility (EIE431)

Eielson Air Force Base, Alaska Alaska District, Pacific Ocean Division

30 January 2019

PN: 471356

Status: Final

Department of the Army Alaska District, U.S. Army Corps of Engineers

P.O. Box 6898

JBER, AK 99506-0898

CEPOA-EN-G-GM 30 January 2019

MEMORANDUM FOR Military Project Management (CEPOA-PM-M), Rebecca Rosenquist

SUBJECT: Consolidated Geotechnical Design Report for the F-35 Conventional Munitions Maintenance Facility PN: 471356 (EIE431), Eielson Air Force Base, Alaska.

1. The U.S. Army Corps of Engineers, Alaska District (USACE) retained R&M Consultants, Inc. (R&M) to perform a geotechnical and environmental investigation for the proposed F-35 Conventional Munitions Facility (EIE431) project on Eielson Air Force Base, Alaska. This work was performed during two efforts in accordance with Contract No. W911KB- 17-D-0001, Delivery Order No. W911KB18F0088 and the same contract with Modification number 02 requiring the additional deep test boring.

2. The original field investigation occurred 31 July through 13 August 2018 and the Geotechnical Data Report was issued 5 October 2018. During this investigation, bedrock was encountered in Test Boring AP-6098 at 100.5 feet below the ground surface. The test Boring is located adjacent to Building 6385 near the southwest corner of the vehicle bays. The designer of record expressed interest further delineating the bedrock surface to enhance their pile design. For this purpose, a modification to the Delivery Order was issued on 27 November 2018 to drill an additional 130-foot test boring. The additional test boring (AP-6124) was drilled to 150.4 feet on 18 and 19 December 2018. It was located north of building 6385 and encountered bedrock was interpreted from about 118.0 feet (elevation 596.5 feet) to the extent of the test boring at 150.4 feet.

3. The Exploration Log AP-6124 was complete 4 January 2019 and was not incorporated into the previously issued Geotechnical Data Report. This memorandum consolidates both documents under one cover. Included in the memorandum is as follows:

a. R&M’s 05 October 2018, EIE431, F-35 Conventional Munitions Maintenance Facility Geotechnical Data Report

b. R&M’s 04 January 2019, EIE431, F-35 Conventional Munitions Maintenance Facility

Independent Exploration Log Memorandum

CEPOA-EN-G-GM

SUBJECT: Consolidated Geotechnical Design Report for the F-35 Conventional Munitions Maintenance Facility (EIE431), Eielson Air Force Base, Alaska.

4. Questions should be addressed to Robert Weakland at 907-753-2633 or John Rajek at 907-753-5695.

ROBERT T. WEAKLAND, P.E.

Civil Engineer

CEPOA-EC-G-GM

JOHN J. RAJEK, P.E.

Chief, Geotechnical and Materials Section

CEPOA-EC-G-GM

DOUGLAS A. BLISS, P.E., P.G.

Chief, Geotechnical and Engineering Services Branch

CEPOA-EC-G

FINAL SUBMITTAL

REVISION 0

GEOTECHNICAL DATA REPORT

EIE431, F-35 CONVENTIONAL MUNITIONS

MAINTENANCE FACILITY

EIELSON AIR FORCE BASE, ALASKA

CONTRACT NO. W911KB-17-D-0001

DELIVERY ORDER NO. W911KB18F0088

PREPARED BY:

R&M CONSULTANTS, INC.

9101 VANGUARD DRIVE

ANCHORAGE, AK 99507

PREPARED FOR:

U.S. ARMY ENGINEER

DISTRICT, ALASKA

CEPOA-EC-G-GM, ROBERT WEAKLAND

2204 TALLEY AVE

JBER, AK 99506

05 OCTOBER 2018

October 05, 2018 R&M No. 2440.09

Mr. Robert T. Weakland Contracting Officers Representative U.S. Army Corps of Engineers, Alaska District VIA EMAIL: robert.t.weakland@usace.army.mil JBER, Alaska 99506

RE: Final Geotechnical Data Report EIE431, F-35 Conventional Munitions Maintenance Facility, Eielson AFB, Alaska IDIQ Contract for Geotechnical Design and Related Services

Contract No. W911KB-17-D-0001, Delivery Order No. W911KB18F0088

Dear Mr. Weakland:

Enclosed, please find our final geotechnical data report prepared for the above referenced project. This work has been completed in accordance with Contract No.

W911KB-17-D-0001, Delivery Order No. W911KB18F0088. This final submittal includes review comments of the draft geotechnical data report made within ProjNet and distributed September 26, 2018.

We trust that this final report is found to be responsive to your requirements.

Should you have any questions or desire for additional information, please do not hesitate to contact us. It has been a pleasure to be of service to the USACE Alaska District on this effort.

Sincerely, R&M CONSULTANTS, INC.

Charles H Riddle, C.P.G.

Senior Vice President

GEOTECHNICAL DATA REPORT - FINAL USACE

EIE431, F-35 CONVENTIONAL MUNITIONS MAINTENANCE FACILITY EIELSON AFB, ALASKA

October 2018 Page i R&M No. 2440.09

GEOTECHNICAL DATA REPORT

F-35 CONVENTION MUNITIONS MAINTENANCE FACILITY (EIE431)

EIELSON AIR FORCE BASE, ALASKA

The following report presents the results of R&M’s geotechnical investigation completed to support design and construction of the programed F-35 Conventional Munitions Maintenance Facility (EIE431) project at Eielson Air Force Base, Alaska. The report includes discussion and results associated with R&M’s review of available existing site data, geotechnical subsurface exploration, and laboratory testing. The geotechnical engineering services performed by R&M Consultants, Inc.

were authorized by the USACE under Contract No. W911KB-17-D-0001, Delivery Order No.

W911KB18F0088.

This report includes both factual and interpretative information and is intended to provide the project designers, construction inspectors, and construction contractors with a summary of the geotechnical conditions expected at the site, and to establish a baseline for assessing changes in geotechnical conditions if or when they are suspected during construction. This report is intended solely for use by USACE and its contractors directly involved with EIE431 project design and construction; contingent upon the reader possessing basic understanding of geotechnical terminology and principles, as well as the referenced documents.

R&M consultants, Inc. has performed this work in a manner consistent with the level of skill ordinarily exercised by members of the profession currently practicing under similar conditions.

No warranty, express or implied, beyond exercise of reasonable care and professional diligence, is made. R&M’s services for the project were performed by, or under the responsible charge of the individuals listed below.

ROBERT M. PINTNER, P.E.

Senior Geotechnical Engineer

Aaron T. Banks, C.P.G.

Senior Geologist

REVIEWED BY:

CHARLES H. RIDDLE, C.P.G.

Senior Vice President

October 2018 Page ii R&M No. 2440.09

TABLE OF CONTENTS

Page Preface and Signatures ................................................................................................................................... i Table of Contents ............................................................................................................................................ ii List of Tables .................................................................................................................................................... iii List of Figures ................................................................................................................................................... iii List of Appendices .......................................................................................................................................... iv Acronyms and Abbreviations ....................................................................................................................... v Executive Summary ....................................................................................................................................... vi

Introduction

1.1 Background

1.2 Contract Authorization

1.3 Concept Plan

1.4 Purpose and Scope-of-Work

1.5 Previous Investigations

1.6 Work Plan Deviations

Regional Setting and General Site Conditions

2.1 Regional Setting

2.1.1 Location

2.1.2 General Geology

2.1.3 General Seismicity

2.1.4 Climate

2.2 General Site Conditions

2.2.1 Topography

2.2.2 Surface Drainage

2.2.3 Vegetative Cover

2.2.4 Soils

2.2.5 Bedrock

2.2.6 Groundwater

2.2.7 Thermal Conditions

2.2.8 Geologic Hazards

Investigation Methods

3.1 Test Boring Positioning

3.2 Test Borings

3.3 Environmental Sampling

3.4 Concrete Coring and Backfilling

Laboratory Testing Program Data Processing and Interpretation

5.1 Test Boring Logs

5.2 Determination of Groundwater

5.3 Determination of Thermal State of Soils

TABLE OF CONTENTS (CONTINUED)

Page

October 2018 Page iii R&M No. 2440.03

Geotechnical Conditions

6.1 Surface

6.2 Soil and Bedrock Conditions

6.2.1 Fill

6.2.2 Silt

6.2.3 Bedrock

6.3 Groundwater

6.4 Thermal Conditions

6.5 Environmental Considerations

6.6 Air Temperature Model

6.7 Geologic and Seismic Hazards

6.7.1 Permafrost

6.7.2 Seismic Parameters

6.7.3 Earthquake-Induced Ground Failure Potential

Conclusions References

LIST OF TABLES

Table 2-1: Eielson AFB Climatological Data Table 3-1: Summary of R&M Test Borings, EIE431 Table 4-1: Laboratory Analysis Methods Table 6-1: Extents of Subsurface Units, EIE431 Table 6-2: Air Temperature Model Parameters Table 6-3: Seismic Design Ground Motion Parameters

LIST OF FIGURES

Figure 1-1: Eielson AFB Regional Area Map Figure 2-1: Instrumented Seismicity Around Fairbanks, 1904-2004 Figure 6-1: Moisture Content, Current Investigation Samples

October 2018 Page iv R&M No. 2440.03

LIST OF APPENDICES

Appendix A – Site Maps Location and Vicinity Map ....................................................................................................................... A-01 Project Area Map ........................................................................................................................................ A-02 Surficial Geologic Map ............................................................................................................................. A-03 Test Boring Locations ............................................................................................................................... A-04 Generalized Geologic Cross Sections ............................................................................... A-05 and A-06

Appendix B – Test Boring Logs General Notes .............................................................................................................................................. B-01 Explanation of Selected Symbols ......................................................................................................... B-02 Explanation of Ice Symbols .................................................................................................................... B-03 Test Boring Logs AP-6091 thru AP-6106 ............................................................................... B-04 to B-37

Appendix C – Laboratory Testing Results Classification of Soils for Engineering Purposes ASTM D 2487 ................................................... C-01 Frost Design Soils Classification ........................................................................................................... C-02 Summary of Laboratory Soils Data ........................................................................................ C-03 to C-18 Gradation Curves ......................................................................................................................... C-19 to C-39 Atterberg Plots ............................................................................................................................................ C-40

Appendix D – Photograph Log EIE431 Surface Conditions Photograph 1 .............................................................................................D-01 EIE431 Surface Conditions Photograph 2.............................................................................................D-01 Fill Materials Sample Photograph ........................................................................................................ D-02 Silt Sample Photograph ........................................................................................................................... D-02 Bedrock Sample Photograph ................................................................................................................. D-03 Massive Ice Sample Photograph ........................................................................................................... D-03

October 2018 Page v R&M No. 2440.03

ACRONYMS AND ABBREVIATIONS

˚F Degrees Fahrenheit ADAL addition or alteration AFB Air Force Base AP auger point ASCE American Society of Civil Engineers ASTM American Society for Testing and Materials International Avg average bgs below ground surface CDR chemical data report CME Central Mining Equipment Company EERI Earthquake Engineering Research Institute EIE431 F-35 Conventional Munitions Maintenance Facility Project Designation g standard acceleration due to gravity GDR geotechnical data report I.D. inside diameter IDW investigation derived waste

in. inch km kilometer LPT large penetration test M local magnitude, unless noted otherwise mm millimeter N, n number NAD83 North American Datum of 1983 NAVD88 North American Vertical Datum of 1988 No. number O.D. outside diameter PCC Portland cement concrete pcf pounds per cubic foot PFOA perfluorooctanoic acid PID photoionization detector ppm parts per million psi pounds per square inch R&M R&M Consultants, Inc.

SEP subsurface exploration plan SOW statement of work SPT Standard Penetration Test USACE United States Army Corp of Engineers, Alaska District USCS Unified Soil Classification System USGS United States Geologic Survey WGS84 World Geodetic Survey 1984 WRCC Western Region Climate Center

October 2018 Page vi R&M No. 2440.09

EXECUTIVE SUMMARY

The U.S. Army Corps of Engineers, Alaska District (USACE) has conducted a geotechnical investigation to provide design information for constructing a new F-35 Conventional Munitions Maintenance Facility, located approximately three miles east of the Eielson Air Force Base main cantonment area and about 25 miles southeast of Fairbanks, Alaska. R&M Consultants, Inc. (R&M), under contract with the USACE, performed a field geotechnical investigation at the site during the period of July 31 through August 13, 2018. The geotechnical investigation was performed concurrently with an environmental investigation, to be reported on under separate cover. The geotechnical investigation including drilling of test borings, sampling and laboratory testing.

Especially significant in the field was determination of depth and classification of fill materials, characteristics and engineering properties of the underlying soils (loess deposits), the classification and interpretation of permafrost, interpretation of groundwater conditions, and identification of any bedrock within depths explored. This report presents a summary of results from R&M’s field subsurface exploration program, a review of existing site geotechnical information, our interpretation of geotechnical site conditions including geologic and seismic hazards.

The site is accessed from Munitions Road and is located on the upper, moderately sloping flank of a ridge at about Elevation 714 feet. Topography across the full facility is generally flat, but bordered with a steep cut slope located immediately south of the site. It is understood that development at the project site will include demolition of the existing Conventional Munitions Facility and construction of a new F-35 Conventional Munitions Maintenance Facility.

A total of sixteen test borings were drilled and sampled by R&M, ranging in depth from 21.5 to

101.5 feet. The total footage drilled during this investigation was 834.5 feet. Laboratory testing of soil samples obtained during the field program was also undertaken for the purposes of material classification and obtaining various index properties of the materials encountered.

Within the project area, the surface is covered with relatively level concrete pavement generally overlying poorly graded gravel with silt and sand (GP-GM) fill material containing cobbles. Soils encountered beneath the fill materials are interpreted to consist of the Fairbanks Loess deposit which is composed of massive, homogenous, unconsolidated eolian silt. The silt (ML) encountered in each of the test borings appears to be essentially uniform with respect to particle size distribution and varies only slightly in color. Moisture contents of the silt ranged from 11 to 84 percent. Permafrost was encountered in six of the sixteen test borings below depths greater than about 20 feet from ground surface, and was generally absent in the test borings nearest Building 6385. The permafrost soils are interpreted to be ice-poor, and presumed to be very warm (e.g.

slightly below 32°F, although there is no ground temperature data at the site). However, massive ground ice was encountered in a single test boring at depths of 24 to 35 feet bgs. A perched groundwater condition was suspected in four test borings overlying permafrost, however, no free water was observed in any borings after drilling. Bedrock was encountered at the project site in one test boring during this investigation at a depth of 100.5 feet.

October 2018 Page vii R&M No. 2440.09

Field screening during site investigation indicated the presence of volatile contamination in Test Boring AP-6098, however, chemical results from Test Boring AP-6098 did not detect analytes exceeding cleanup levels in samples collected from this test boring. Chemical testing results detected PFOA at a level exceeding cleanup levels in Test Boring AP-6095. Arsenic was detected above established background levels for loess in Test Borings AP-6102 and AP-6104. For detailed information regarding field screening and chemical testing results, the reader is referred to the EIE431 Chemical Data Report, published under separate cover.

Based on the results of this geotechnical investigation, the potential geologic hazards considered most likely to affect design and construction of the EIE431 project include permafrost and earthquakes (i.e. strong ground shaking and liquefaction). The project designers will need to consider the potential of long-term differential settlements under the proposed new building due to permafrost degradation induced by the new heated structure. Further, the permafrost soils once thawed are expected to be susceptible to earthquake induced liquefaction. Designers will also have to evaluate the need for deep ground improvement, as a function of the total and differential settlement the structure can tolerate.

October 2018 Page 1 R&M No. 2440.09

INTRODUCTION

1.1 BACKGROUND

The U.S. Army Corps of Engineers, Alaska District (USACE) is presently conducting a geotechnical investigation to provide subsurface information for constructing a new F-35 Conventional Munitions Maintenance Facility (EIE431) to support the addition of an F-35A squadron at Eielson Air Force Base, Alaska. Work consisted of geotechnical drilling, sampling, and laboratory testing. Of special significance were the classification and interpretation of permafrost, and the classification and engineering properties of the soils. It is understood that the geotechnical data will be used in developing the design criteria and specifications for the project. This report presents the results of the field investigation and interpretation of site conditions. Figure 1 provides a map of the project area.

The USACE contracted R&M Consultants, Inc. (R&M) to complete a subsurface exploration program and provide geotechnical and chemical data reports for the EIE431 project. This document is the EIE431 Geotechnical Data Report (GDR). The EIE431 Chemical Data Report (CDR) is provided under separate cover.

The site description and subsurface conditions presented herein are based on our current understanding of the project and location as outlined within and illustrated on the drawings included in the appendices to this report. Any deviation from the proposed location would necessitate further evaluation of subsurface conditions.

1.2 CONTRACT AUTHORIZATION

This study has been conducted under the terms of Contract No. W911KB-17-D-0001 between the USACE and R&M. This report is in specific fulfillment of Delivery Order No. W911KB18F0088 of the contract. Measurements and weights presented in this report are generally shown as U.S.

Customary Units.

1.3 CONCEPT PLAN

Development at the EIE431 project site is understood to include construction of a new conventional munitions maintenance facility building. Design information for the new structure is very limited, as important design decisions have not yet been made.

The existing munitions facility building location, and site conditions are presented on Drawing A- 04 in Appendix A. The proposed new structure layout is currently unavailable at the time of this report. Drawing A-04 also displays the location of a former munitions maintenance shop building, which was demolished prior to earthwork and construction of the existing facility (USACE, 2000).

October 2018 Page 2 R&M No. 2440.09

FIGURE 1-1: EIELSON AFB REGIONAL AREA MAP

1.4 PURPOSE AND SCOPE-OF-WORK

The intent of this geotechnical investigation was to gather data on the geologic and geotechnical conditions which could affect site planning, design and construction of the proposed new building and to provide specific geotechnical design information for earthwork and utility design and construction for the specified facilities. Geotechnical investigations were performed in accordance

October 2018 Page 3 R&M No. 2440.09 with procedures, as outlined in “Geotechnical Investigations” (USACE, 2001). Geotechnical investigation services consisted of office research, geotechnical drilling, sampling and laboratory testing. Of special significance was the determination of groundwater depth, interpretation of permafrost conditions, and the classification of the engineering properties of the site soils.

Geotechnical investigation activities in support of the EIE431 project were performed in accordance with the USACE’s Statement of Work (SOW) and the Subsurface Exploration Plan (SEP) prepared by R&M (R&M, 2018).

A SOW prepared by the USACE, dated June 7, 2018, summarized the Scope-of-Work for this project.

The work performed by R&M in support of the geotechnical effort consisted of the following:

• Provide all supervision, labor, materials, tools, equipment and transportation necessary to perform the field work.

• Provide coordination of scheduling with USACE and Eielson AFB personnel.

• Procure all required permits, utility locates and dig permit clearances.

• Establish boring locations based on mapping-grade global positioning system equipment.

• Prepare daily logs of all operations, observations and measurements, and compiling these logs into the specified field report.

• Provide subcontract drilling contractor.

• Provide subcontract asphalt coring and patching services.

• Provide supervision of drilling and soil sampling, backfilling and plugging of borings, moves between borings and clean-up of work areas.

• Provide preservation and transportation of soil samples (including permafrost samples), measurement of groundwater levels and soil temperatures and preparation of soil boring logs.

• Provide all supervision, labor, materials, tools, equipment and transportation necessary to perform laboratory testing of soils.

• Prepare draft and final geotechnical data reports presenting the results of drilling and sampling, laboratory testing, field methodology and operations, and data interpretations.

Test boring depths and locations were specified by USACE in the SOW.

1.5 PREVIOUS INVESTIGATIONS

Other geotechnical investigations have been performed within the vicinity of the existing Munitions Facility Building (No. 6385). The USACE performed a geotechnical investigation in 1995 for construction of the existing Building 6385 (USACE, 1995). Shannon & Wilson, Associates completed geotechnical explorations in 2016 as part of a study into Building 6385 settlements (Design Alaska, 2016). More recently, R&M performed a geotechnical investigation in March 2017 at the site that included a discussion of foundation performance of the existing building (R&M, 2017).

October 2018 Page 4 R&M No. 2440.09

1.6 WORK PLAN DEVIATIONS

Several deviations from the approved work plan occurred and are described below.

• Test Boring TB-19 was deleted from the program, prior to drilling, per direction from the

USACE.

• Test Borings AP-6091, AP-6095, AP-6096, AP-6097, AP-6098, AP-6101, AP-6103, AP-6104, AP-6105 and AP-6106 were shifted from their original planned locations to avoid both underground utility and overhead utility conflicts.

• LPT samples were generally obtained at intervals where both a geotechnical and environmental sample were prescribed in order to collect enough volume to satisfy both geotechnical and environmental sample volume requirements.

October 2018 Page 5 R&M No. 2440.09

REGIONAL SETTING AND GENERAL SITE CONDITIONS

2.1 REGIONAL SETTING

2.1.1 LOCATION

The project site is situated within Eielson AFB and is located on USGS Big Delta (C-6) Quadrangle, Township 3 South, Range 4 East, Section 8, Fairbanks Meridian, Alaska. The site is located at

64.6618 degrees North, and 146.9894 degrees West, in WGS84 decimal degree coordinates, based on Google Earth Pro.

The site is approximately three miles east of the Eielson AFB runway and approximately 25 statute miles southeast of Fairbanks, Alaska (Figure 1-1). The Trans-Alaska Pipeline is located approximately one-half mile west of the project site. The Richardson Highway, also known as the Alaska Highway in this area (Alaska Route 2), is located about three miles west of the site. The main entrance to Eielson AFB is at about Milepost 341 of the Richardson Highway. The site is situated along an unimproved military roadway known as Munitions Road.

2.1.2 GENERAL GEOLOGY

Eielson AFB lies on the margin of the Yukon-Tanana Upland physiographic province adjacent the Tanana-Kuskokwim Lowlands (Wahrhaftig, 1965). The Yukon-Tanana Upland is characterized by rounded summits generally between 1,500 and 3,000 feet in elevation, dissected by mature stream valleys. Tributaries to the stream systems originate in narrow steep valleys and gullies, which tend to widen to broad, poorly drained, gently sloping alluvial fans at confluences of major streams. Stream erosion has been the dominant influence in shaping the topography. The adjacent Tanana-Kuskokwim Lowlands is a broad depression bordering the Alaska Range to the south and the Yukon-Tanana Uplands to the north, characterized by glacial moraines, outwash plains, terraces and floodplains formed by glaciers and streams flowing northward from the Alaska Range. The majority of the Yukon-Tanana Uplands, including the project area, has not been glaciated (Coulter et al., 1965).

Bedrock within this portion of the Yukon-Tanana Upland generally consists of Precambrian or Paleozoic-age schist and greenstone which may have been intruded by Mesozoic and Tertiary plutons (Péwé et al., 1966). The bedrock is mostly covered by surficial soil deposits, which may be absent in select areas and on ridge tops and tend to thicken downslope. The project area is mantled with surface sediments mapped as Quaternary loess (windblown silt) deposits (Weber et al., 1978). A surficial geologic map of the area is provided in Appendix A as Drawing A-03. The silt deposits are described as being massive, homogenous, unconsolidated and well-sorted (Péwé et al., 1966). The silt deposits on hillsides with northern exposure tend to be perennially frozen where undisturbed and may contain high ice content. The silt on lower slopes generally also contain organics and rock fragments due to reworking of the deposits.

This area is considered to generally be underlain by discontinuous permafrost (Jorgenson et al., 2008). Both temperature of permafrost at depth just below the zone of seasonal variation, and air temperature are extremely variable in regions of discontinuous permafrost.

October 2018 Page 6 R&M No. 2440.09

Regional geology of the Yukon-Tanana Upland is further discussed in Foster et al. (1994 and 1973).

Geologic mapping has been published at a scale of 1:250,000 (1 inch = 4 miles) by the USGS for the Big Delta (Weber et al., 1978) and Fairbanks (Péwé et al., 1966) quadrangles. Additionally, preliminary engineering geology maps for the area have been prepared by Carter and Galloway (1978) and Weber (1971) at a scale of 1:125,000 for the proposed natural gas pipeline and the Trans- Alaska Pipeline, respectively. Although quite dated, geologic mapping at a scale of 1:63,650 (1 inch = 1 mile) is available for adjacent areas (Williams, 1959).

2.1.3 GENERAL SEISMICITY

Seismicity across interior Alaska is characterized by frequent, moderate to strong (M5 to +M7), shallow crustal earthquakes, associated with convergence and subduction of the Pacific plate underneath the North American plate along southcoastal Alaska (Davies, 1983). The Fairbanks region is bounded by two large-scale, strike-slip fault systems (Ruppert et al., 2008), including the recently active Denali fault about 90 miles south of Fairbanks, and the Kaltag-Tintina fault about 65 miles north of Fairbanks. There are no Quaternary age faults known within about 60-70 miles of the project (Koehler, 2013); however, the majority of historic earthquakes within this area (at least 11 instrumented earthquakes with local magnitude (ML) greater than 5 have been cataloged1 since 1900) have been clustered in three linear, north-northeast trending “seismic zones” (Minto Flats, Fairbanks, and Salcha)(Ruppert et al., 2008) – the Eielson AFB is situated within the Salcha Seismic Zone. Figure 2-1 illustrates the earthquakes recorded in the Fairbanks area between 1904 and 2004.

1 Alaska Earthquake Center: http://www.giseis.alaska.edu/Seis/ http://www.giseis.alaska.edu/Seis/

October 2018 Page 7 R&M No. 2440.09

FIGURE 2-1: INSTRUMENTED SEISMICITY AROUND FAIRBANKS, 1904-2004

(Base map from Alaska Earthquake Center. Gold Star = Conventional Munitions Facility, Eielson AFB; red lines = faults; black lines = roads; yellow line = pipeline. FSZ = Fairbanks Seismic Zone;

MFSZ = Minto Flats Seismic Zone; SSZ = Salcha Seismic Zone. Notable earthquakes (red & yellow dots) include: a – MS7.2 in 1947, b – ML7.3 in 1904, c - ML7.3 in 1937, d – ML6.1 in 1967, e – ML6.1 in 1967, f – MS6.2 in 1929, g – MS6.5 in 1929, and h – ML6.2 in 1995)

2.1.4 CLIMATE

Eielson AFB is subject to an interior continental climate regime, characterized by light precipitation, cold dry winters, and warm summers. Based on climate data recorded at the Eielson Field weather station from 1949 to 2011: the mean annual air temperature is approximately 26.4 °F, with mean monthly averages ranging between approximately -9.8 °F (January) and 61.0 °F (July); and the area received an average of approximately 12.9 inches of precipitation per year, with about 70 inches of snow and a maximum monthly mean of approximately 7.5 inches of precipitation in August (WRCC, 2018).

A summary of climatological data obtained from the Eielson AFB recording station is presented in Table 2-1.

a b c d e h f g

SSZ

FSZ

MFSZ

October 2018 Page 8 R&M No. 2440.09

TABLE 2-1: EIELSON AFB CLIMATOLOGICAL DATA

Weather Station Parameter Eielson Field (Station No. 502707)

Period of Record 1949 to 2011 Mean Annual Temperature (°F) 26.4

Mean Max. Daily Temperature (°F) 36.0 Mean Min. Daily Temperature (°F) 16.8

Record High Temperature (°F) 93 (15 June 1969) Record Low Temperature (°F) -64 (23 January 1971)

Mean Annual Precipitation (in.) 12.86 Mean Maximum Monthly Precipitation (in.) 2.51 (July)

Maximum Daily Precipitation (in.) 3.61 (12 August 1967) Mean Annual Snowfall (in.) 70.9

Mean Maximum Monthly Snowfall (in.) 13.7 (November) Maximum Monthly Snowfall (in.) 58.7 (November 1990)

NOTES:

After Western Regional Climate Center (www.wrcc.dri.edu)

2.2 GENERAL SITE CONDITIONS

2.2.1 TOPOGRAPHY

The site is located on the lower, moderately sloping northwestern flank of a ridge that rises from an elevation of approximately 715 feet at the project site to 1,125 feet approximately one mile to the southeast. The Tanana “Flats” upon which Eielson AFB lies is at about elevation 525 to 550.

Based on surveys performed by others, elevations at the site range from about 700 feet along Munitions Road to about 730 feet at the edge of the forest behind the site. Contour mapping with a contour interval of 1 foot is provided on the Test Boring Locations Map presented as Drawing A- 04 of Appendix A.

2.2.2 SURFACE DRAINAGE

Surface drainage appears to occur by sheet flow or by percolation into any surrounding unfrozen soils. An existing French drain system is installed along the south side of the facility.

No seeps were observed in the project area.

2.2.3 VEGETATIVE COVER

Generally, the upland areas east of Eielson AFB are considered to be with the upland spruce-hardwood forest biotic community (AEIDC, 1976). In this biotic community, white spruce with scattered birch or aspen is commonly found on moderate south-facing slopes while black spruce is found on north-facing exposures and poorly drained flat areas. The understory typically includes high and low shrubs and a carpet of ferns, mosses, and lichens.

Outside of the cleared project site, natural areas are sparsely to heavily wooded by spruce and birch.

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2.2.4 SOILS

The following paragraphs present very general comments regarding area-wide soil types. Detailed discussion of soils encountered at the project site during R&M’s subsurface investigation are provided in Section 6.

Soils at the proposed EIE431 site are interpreted as the Fairbanks Loess deposit which is composed of massive, homogenous, unconsolidated eolian silt. Fairbanks loess is the most widespread deposit of Quaternary-age in central Alaska and blankets the hills in the area, especially below the elevation of about 2,000 feet (Péwé, 1975). The material is described as buff to tan-gray when dry and brown when wet. In many areas thin, dark carbonaceous layers and iron oxide stains may be present. On steeper side slopes, this material may also contain deposits of retransported silt.

Carter & Galloway (1978) present the following general properties of eolian silts in the Fairbanks area:

Drainage Generally good.

Permafrost Absent on tops of hills and upper slopes and generally absent throughout well-drained south facing slopes. Ground ice masses present locally under north facing slopes and poorly drained areas.

Susceptibility to Frost Action Moderate to low; locally high if drainage poor.

Susceptibility to Erosion Highly susceptible to gullying; subject to piping and hydroconsolidation. Barren slopes susceptible to deflation (a form of wind erosion [Neuendorf et al., 2005]). Subject to subsidence upon melting of ice-rich permafrost that is locally present under north-facing slopes and in poorly drained areas.

Excavation and Compaction Easy to excavate with power equipment except where frozen. Ripping or blasting required where frozen. Difficult to compact.

Suitability for Construction Good foundation material if protected against wetting. Unsurfaced roads built on eolian silt are muddy when wet and dusty when dry. Possible source of fines for blending.

General Remarks Vertical to near vertical artificial cuts will be stable if adequate drainage is provided.

October 2018 Page 10 R&M No. 2440.09

Typical soil index properties for this material have been reported in several publications (Kreig & Reger, 1982 and Morrison, 1968) as follows:

• Gradation: 83 to 97% silt, 3 to 17% clay

• Moisture Content: 5 to 45%, Avg. 24%

• Dry Density: 66 pcf to 108 pcf, Avg. 85 pcf

• Liquid Limit: 31.8 to 21.8, Avg. 25.3

• Plastic Index : 7.3 to 1.1, Avg. 3.4 (60% were non-plastic)

2.2.5 BEDROCK

Based on published data, the scattered bedrock outcrops which occur within the general area expose rock types typical of the Yukon-Tanana Upland: Precambrian or Paleozoic-age schist, quartzite, mylonite, green schist, phyllite, marble, slate and greenstone, and Tertiary-age granitic rocks of the Eielson Pluton. The name “Birch Creek Schist” has been applied to all of the older Precambrian metamorphic rocks of the area that are of sedimentary origin.

Further discussion of bedrock conditions is presented in Section 6

2.2.6 GROUNDWATER

What appeared to be a perched groundwater condition was encountered in only four of R&M’s test borings. Groundwater was not encountered within any of the other R&M test borings to the total depths explored.

Further discussion of on-site groundwater conditions is presented in Section 6.

2.2.7 THERMAL CONDITIONS

As previously mentioned, the area is considered to generally be underlain by discontinuous permafrost. Geologic mapping indicates that permafrost is absent on tops of hills and upper slopes and generally absent throughout well-drained south-facing slopes. However, permafrost and ground ice masses are present locally under north-facing slopes and poorly drained areas.

Further discussion of site thermal conditions is contained in Section 6.

2.2.8 GEOLOGIC HAZARDS

Péwé (1982) cites frozen ground, groundwater, earthquakes, landslides, hillside erosion in loess and flooding to be the primary geologic hazards encountered in in this area. At the project site, the hazards of greatest concern are earthquakes and frozen ground. Further discussion of geologic and seismic hazards is provided in Section 6.

October 2018 Page 11 R&M No. 2440.09

INVESTIGATION METHODS

Methods of investigation for the EIE431 geotechnical field investigation are described in the following sections.

3.1 TEST BORING POSITIONING

Test boring depths and locations for EIE431 were specified by USACE in the SOW and preliminary coordinates were provided by the USACE prior to field mobilization. R&M established final test boring locations as part of the Base Civil Engineer Work Clearance Request process. As detailed in Section 1.6, ten boreholes required a slight offset from their preliminary coordinates to their final coordinates in order to avoid conflicts with either underground utilities or overhead utilities.

Horizontal borehole locations were established using a mapping grade global positioning system, with a reported accuracy of three feet. Vertical coordinates were interpolated by R&M after drilling from a current USACE survey drawing titled “EIE387-vf01.dwg”.

The final location of test borings drilled during the current investigation is presented in Appendix A on Drawing A-04. Coordinates and surface elevation information for the test borings are provided in tabular form on Table 3-1, below, and on the test boring logs in Appendix B.

TABLE 3-1: SUMMARY OF R&M TEST BORINGS, EIE431

Test Boring

Number (Final)

Test Boring

Number (Field)

Coordinatesa

Collar

Elevationa, Interpolated

Total Depth (Feet)

Approximate Depth to Perched

Groundwater (Feet)

Approximate Depth to

Permafrost Top/Bottom

(Feet) Northing Easting

AP-6091 TB-20 3,897,516 1,485,173 713.1 21.5 NEc 20.7/TD

AP-6092 TB-21 3,897,479 1,485,188 713.1 21.5 NEc NEc

AP-6093 TB-22 3,897,581 1,485,201 713.1 21.5 NEc NEc

AP-6094 TB-23 3,897,534 1,485,220 714.0 21.5 NEc NEc

AP-6095 TB-24 3,897,503 1,485,236 714.1 51.5 NEc NEc

AP-6096 TB-25 3,897,594 1,485,250 713.9 101.5 NEc 49.0/78.0

AP-6097 TB-26 3,897,553 1,485,261 714.7 101.5 NEc NEc

AP-6098 TB-27 3,897,507 1,485,273 714.8 101.2 NEc NEc

AP-6099 TB-28 3,897,672 1,485,252 700.1 21.5 NEc NEc

AP-6100 TB-29 3,897,616 1,485,307 714.3 101.5 34.0b 48.0/82.5

AP-6101 TB-30 3,897,643 1,485,351 712.3 21.5 NEc NEc

AP-6102 TB-31 3,897,592 1,485,370 713.5 21.5 NEc NEc

AP-6103 TB-32 3,897,559 1,485,449 713.5 22.0 NEc NEc

AP-6104 TB-33 3,897,582 1,485,583 711.0 51.5 10.0b 24.5/TD

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NOTES:

a Alaska State Plane Zone 3 NAD83 (horizontal) and NAVD88 (vertical), U.S. Survey Feet.

b Perched groundwater observed by R&M Geologist.

c Interpreted by R&M Geologist to have not been encountered while drilling.

TD=Total Depth

3.2 TEST BORINGS

R&M completed a total of sixteen (16) test borings, numbered AP-6091 through AP-6106, at the EIE431 project site during the period of July 31 through August 13, 2018. The depth of the test borings ranged from 21.5 to 101.5 feet bgs. The total footage drilled was approximately 834.2 lineal feet. The drilling program was conducted under the direct guidance of an experienced R&M engineering geologist who maintained detailed logs of the materials encountered and the samples collected. Each test boring was logged in accordance with standard engineering practices.

Data obtained from the test boring were utilized for geologic interpretations. A key to the test boring log general notes, an example of a typical log, and an explanation of the ice symbols used on the logs are illustrated in Appendix B on Drawings B-01, B-02, and B-03, respectively. The test borings logs are illustrated on Drawings B-04 through B-37. Table 3-1, above, provides a summary of the R&M test borings performed for the project.

Drilling and sampling operations were performed by Discovery Drilling, Inc. under contract with R&M, utilizing a truck-mounted CME-75 drill rig. Test borings were accomplished using continuous-flight, 3 1/4-inch inside diameter (I.D.) hollow-stem augers. Drive samples were collected at intervals of approximately 2.5 feet within the top 10 feet of the boreholes and at 5-foot intervals thereafter.

Samples were obtained using split-barrel sampling equipment in general accordance with ASTM D 1586, “Standard Penetration Test (SPT) and Split Barrel Sampling of Soils”. However, a Large Penetration Test (LPT) split-barrel sampling method was utilized between select depths of about 5 feet and 15 feet at environmental sampling intervals for the purpose of collecting enough sample volume for both environmental and geotechnical samples. This sampling method is a modification of the SPT and was accomplished by driving a 2.5-inch I.D. by 3.0-inch O.D. heavy-wall split-barrel drive sampler by the impact of a 340-pound automatic hammer falling 30 inches.

When environmental sampling intervals were not prescribed, the SPT method was used. The SPT’s were accomplished by driving a 1.4-inch I.D. by 2.0-inch O.D. heavy-wall split-barrel drive sampler by the impact of a 140-pound automatic hammer falling 30 inches.

The penetration resistance, defined as the number of blows to drive the sampler the last 12 inches of an 18-inch interval, gives an indication of the in-place relative density for unfrozen cohesionless soils. Blow counts reported per six-inch interval are shown on the boring logs in Appendix B. The SPT “N” value is the number of blows required to drive the 1.4-inch I.D. sampler, with a 140-pound hammer the last 12 inches of an 18-inch interval. Penetration resistance obtained with the 2.5-inch I.D. sampler can be factored to approximate the equivalent SPT “N” value by a hammer potential energy to sampler end-area ratio adjustment. Please note; however, that the blow counts that

TABLE 3-1: SUMMARY OF R&M TEST BORINGS, EIE431 (CONTINUED)

AP-6105 TB-34 3,897,588 1,485,624 711.0 51.5 9.8b 20.6/51.0

AP-6106 TB-35 3,897,593 1,485,643 711.0 101.5 10.0b 22.0/79.0

October 2018 Page 13 R&M No. 2440.09 appear on the log of test borings for the 2.5-inch I.D. samplers are actual values, not the converted SPT values.

Frozen soils were described using ASTM Designation D 4083 (Standard Practice for Description of Frozen Soils, Visual-Manual Procedure). After visual and tactile classification in the field, soil samples were returned to the R&M laboratory. Representative soil samples were then selected for further examination and analysis.

3.3 ENVIRONMENTAL SAMPLING

Test boring soil samples were field screened during the geotechnical investigation using visual, olfactory, and photoionization detector (PID) methods for detecting signs of hydrocarbon contamination. Soil field screening was conducted using the heated headspace method. The results of PID screening are presented on the test boring logs, in parts per million (ppm).

Additionally, select samples were retained for chemical testing. These samples are identified on the logs using ‘Chem Sample:’ followed by the sample designation and test depth. Often these samples required the complete recovery of soil in that interval, leaving no material for geotechnical testing. For more information regarding PID screening or chemical testing refer to the EIE431 Chemical Data Report, to be released under separate cover following release of this report.

3.4 CONCRETE CORING AND BACKFILLING

Concrete coring operations were required in order to advance some of the test borings through the existing pad pavement. This was achieved using an electric concrete coring tool that connected to a portable generator and cut a 10-inch diameter core through the concrete slab.

Once the cut was complete, a hand operated roto-hammer was utilized to remove the core from the hole allowing for drilling and sampling operations to be accomplished.

Following drilling and sampling operations, fifteen boreholes were backfilled in accordance with the Subsurface Exploration Plan method for backfill of non-contaminated boreholes. Boreholes were backfilled and compacted with non-contaminated drill cuttings and sealed with a bentonite hole plug at a depth between 2 and 5 feet bgs. The remaining portion of the borehole was backfilled with local soil and compacted. Boreholes located within the existing pad pavement were backfilled to allow a minimum of eight inches for a concrete patch.

One borehole, AP-6098, was backfilled in accordance with the Subsurface Exploration Plan method for backfill of contaminated boreholes. This borehole was backfilled with bentonite hole plug from total depth to 2 feet bgs. The remaining portion of the borehole was backfilled with pea gravel and compacted to allow a minimum of eight inches for a concrete patch. Soil cuttings from this borehole were containerized, in accordance with the approved Sampling and Analysis Plan (R&M, 2018), within sealed open-top 55-gallon steel drums and transferred to the Eielson Land Fill 3 (LF003) IDW facility. Once environmental laboratory results from these drums are received, they will be disposed of in a manner consistent with Federal, State, and local regulations.

Concrete core holes were then patched with Dayton Superior HD-50, an approved patching compound, a minimum of eight inches thick.

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LABORATORY TESTING PROGRAM

The laboratory testing program was developed to provide data on the important soil characteristics necessary for subsurface characterization of the site. These tests verified and modified the field descriptions, improving the data base for engineering application and geotechnical interpretation of site conditions. Laboratory testing was performed in accordance with the following ASTM procedures (ASTM, 2018).

TABLE 4-1: LABORATORY ANALYSIS METHODS

Test Procedure

ASTM

Designation

Classification of Soils for Engineering Purposes D 2487

Description and Identification of Soils (Visual-Manual Procedure) D 2488

Particle-Size Analysis of Soils (Standard sieve analysis which includes percent passing No.

200 sieve and two-hour hydrometer for percent passing 0.02)

D 422

Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass D 2216

Liquid Limit, Plastic Limit and Plasticity Index of Soils D 4318

In addition to the Unified Soil Classification System (USCS), the samples were given a frost classification based on the U.S. Army Corps of Engineers Frost Design Soil Classification method (USDD, 2004). Each classification method (USCS and USACE) is presented on the log of test boring and laboratory data summary for those respective samples tested. When either the USC or the Frost Design Soil Classification was estimated, the estimated classification symbol is followed by an asterisk (*) on the log of test boring and laboratory data summary.

The Unified Soil Classification System and Frost Design Soil Classification are presented in Appendix C on Drawings C-01 and C-02, respectively. A summary of laboratory test results is provided on Drawing C-03 through C-18. Gradation curves are plotted on Drawings C-19 through C-39. A plot of plasticity (Atterberg limits) testing results is presented on Drawing C-40.

It should be noted that the size of the gravel particles in the samples obtained in a 1.5 or 2.5-inch I.D. spilt-spoon sampler is limited by the size of the opening of the sampler, therefore the sample is thus not necessarily representative of the coarse gravel fraction.

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DATA PROCESSING AND INTERPRETATION

Interpretation of geotechnical data included the integration of the field boring logs, laboratory test data, and data obtained from the prior investigations. U.S. Geological Survey maps and reports in addition to on-site survey data were also helpful in interpreting site conditions.

5.1 TEST BORING LOGS

R&M engineering geologists maintained field logs documenting the drilling method, progress, and samples attempted and recovered; a description of the recovered soil (following ASTM D 2488); and our interpretation of the geotechnical conditions between the recovered samples. The formal logs provided in Appendix B include additional modifications based on further visual inspection of the recovered samples, and the results of the laboratory testing (Appendix C). It is imperative for users to recognize that the formal logs: (i) include factual data (e.g. SPT/LPT blow counts and laboratory test results) as well as interpretative information (e.g. conditions between sample depths, etc.); (ii) use soil group names assigned following the Unified Soil Classification System (USCS, ASTM D 2487); and (iii) use USCS soil group names with an asterisk (e.g. SM*) where the grain-size distribution was measured but the plasticity was estimated using visual-manual procedures (ASTM D 2488).