GEOTECHNICAL REPORT US 93 WILDLIFE UNDERCROSSINGS North of Wells, Nevada E.A July 2009

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1 GEOTECHNICAL REPORT US 93 WILDLIFE UNDERCROSSINGS North of Wells, Nevada E.A July 2009 MATERIALS DIVISION

2 STATE OF NEVADA DEPARTMENT OF TRANSPORTATION MATERIALS DIVISION GEOTECHNICAL SECTION GEOTECHNICAL REPORT US 93 WILDLIFE UNDERCROSSINGS North of Wells, Nevada July 2009 E.A ELKO COUNTY, NEVADA Prepared by: Dana Boomhower Senior Materials Engineer - Geotechnical Reviewed by: Jeff Palmer, Ph.D., P.E. Principal Geotechnical Engineer Approved by: Reid Kaiser, P.E. Chief Materials Engineer ii

3 TABLE OF CONTENTS INTRODUCTION...1 General...1 Purpose and Scope...1 PROJECT DESCRIPTION...2 GEOLOGIC CONDITIONS and SEISMICITY...2 FIELD INVESTIGATION...3 LABORATORY ANALYSIS...4 DISCUSSION...5 RECOMMENDATIONS...5 Excavation...5 Foundations...6 Settlement...6 Lateral Load Analysis...6 REFERENCES...7 APPENDICES APPENDIX A... Project Location Area Map...Borehole Location Sheets APPENDIX B...Boring Log Key...Boring Logs APPENDIX C...Soil Particle Size Distribution Sheets (Gradation Curves)...Test Result Summary Sheets iii

4 INTRODUCTION General This report has been prepared for the three planned wildlife undercrossing structures on US 93 in Elko County, Nevada. A Preliminary Design Field Study (PDFS) held on June 10 th, 2009 identified the area under consideration as being between mileposts 82 and 95, north of Wells, Nevada (See Photo 1). This area has been identified as one of the higher areas of vehicle/animal conflicts in the state. The area is shown on the Project Location Area Map in Appendix A. Photo 1. Looking north-northeast along US 93. Purpose and Scope The purpose of this report is to provide information regarding the subsurface soil conditions at the proposed project site. This report also provides geotechnical design recommendations for the construction of the structures proposed for this project. The scope of this report consists primarily of geotechnical exploration, analysis, and recommendations for both design and construction. The investigation included gathering 1

PROJECT DESCRIPTION The project site is located north of the city of Wells in Elko County. US 93 runs roughly north/south in the area of the proposed structures.

5 information obtained from previous subsurface explorations, soil sampling, and analysis of field and laboratory testing data. This report includes boring logs and summaries of test results from both the field investigations and laboratory testing. These may be found in appendices B and C, respectively. PROJECT DESCRIPTION The project site is located north of the city of Wells in Elko County. US 93 runs roughly north/south in the area of the proposed structures. Preliminary plans indicate the proposed structures will be constructed using prefabricated elliptical sections placed beneath the roadway. Other types of prefabricated structures may also be considered. Undercrossings are planned to be located at approximately milepost 82.2, 84.6, and GEOLOGIC CONDITIONS and SEISMICITY The four sites that were drilled are founded primarily in quaternary alluvium (Qa) 1. These deposits are generally light to medium to dark brown clayey sands and clayey gravels (See Photos 2 and 3). This area lies at an elevation of between approximately 5900 feet and 6200 feet and slopes downward to the west northwest. The site is located between the HD range to the east and the Snake Mountains to the west. 2 Groundwater was found in Boreholes WC-4 and WC-5 at depths of approximately 30.0 and 25.1 respectively. Photos 2 and 3. Soil Samples 2

6 FIELD INVESTIGATION The Geotechnical Section performed site exploration in four areas being considered for wildlife undercrossings from milepost 82.2 to milepost 95.2 on US 93, north of Wells in Elko County. The purpose of this exploration was to determine the feasibility of placing prefabricated structures beneath US 93 to serve as wildlife undercrossings for local animal populations. Five boreholes were drilled on June 23 and 24, The five borehole locations were all located in areas of embankment fill, which were from approximately 10 feet to 23 feet in height above native ground. All boreholes were drilled through the pavement and fill, into the native ground, to characterize its relative excavatability. Subsurface soil conditions were explored by drilling five boreholes placed near the proposed locations for the wildlife undercrossings. The approximate location of each borehole is shown on the Borehole Location sheet in Appendix A. Boreholes WC-1 through WC-5 were drilled to depths between 25.3 feet and 56.0 feet. The surface elevations were obtained for the borehole locations by surveying from a known elevation point, except for borehole WC-1, which was approximated from roadway design mapping information. Drilling was accomplished with a Diedrich D-120 drill rig equipped for soil sampling, using 6-inch hollow stem auger on all boreholes (See Photo 4). Soil samples and standard penetration resistance values (N-Values) were obtained utilizing the Standard Penetration Test (SPT) procedure as set forth in AASHTO test number T206. Larger samples were obtained with a California Modified Sampler (CMS), using the procedure as set forth in ASTM test number D The uncorrected blow counts are shown on the boring logs in Appendix B. All soil samples were classified, both visually and using laboratory data, using the Unified Soil Classification System (USCS) described in ASTM test number D

7 Photo 4. Drill Rig Setting Up on Borehole WC-4. LABORATORY ANALYSIS Laboratory tests were performed on the samples collected from the boreholes. The testing program consisted of sieve analyses, moisture contents and unit weights, Atterberg limits, and specific gravities. The results of this testing program show that the soils consist primarily of clayey sands and gravels (>80%), with the remainder being lean and fat clays (<20%). Dry unit weights from 43 samples ranged from 86.4 pounds per cubic foot (pcf) for sample WC-4 E (lean clay with sand); to pcf for sample WC-4 H (clayey sand with gravel) (See Photos 5 and 6). Further information is presented in the summaries of test results in Appendix C. 4

fat clays, and loose silty sands (23%). Liquefaction is unlikely to occur due to soil type and density, as well as the depth of the water table in the region.

8 Photos 5 and 6. Samples WC-4 E and H. DISCUSSION Following the field investigation and laboratory testing, the soils were identified as primarily medium dense to dense clayey sands and gravels (69%), and medium stiff to stiff lean and fat clays, and loose silty sands (23%). Liquefaction is unlikely to occur due to soil type and density, as well as the depth of the water table in the region. RECOMMENDATIONS Excavation All excavation shall be performed in accordance with the NDOT 2001 Standard Specifications for Road and Bridge Construction 4. All permanent slopes should be constructed to lie at a maximum of 2:1 (Horiz:Vert) slope. The contractor shall be responsible for all necessary shoring for any excavation and/or construction. Variable site conditions always include the possibility of encountering very soft soils, boulders, or other adverse soil conditions in native ground, that were not identified in this investigation. 5

9 Foundations Spread footings for retaining walls placed in embankments have an allowable bearing capacity of 4000 psf (4 ksf). Those in native soil have an allowable bearing capacity of 5000 psf (5 ksf). Settlement The estimated settlement of the structure abutments is negligible under the anticipated loading due to the type of construction to be performed. The removal of embankment soil necessary for the construction of the undercrossing structures will reduce the surcharge loading on the native ground. Lateral Load Analysis The following parameters are provided for seismic evaluation 3. Peak Ground Acceleration coefficient = 0.15g Seismic Performance Category = B Soil Profile = Type III Site Coefficient (S) = 1.5 6

10 REFERENCES 1. Geologic Map of Elko County, Nevada, Bulletin 101, Plate 1; Nevada Bureau of Mines and Geology, Bulletin 101, Geology of Elko County, Nevada; Nevada Bureau of Mines and Geology, AASHTO Standard Specifications for Highway Bridges, 17th edition, Standard Specifications for Road and Bridge Construction, State of Nevada Department of Transportation,

11 APPENDIX A Project Location Area Map Borehole Location Sheets

12 PROJECT LOCATION AREA MAP

13 BOREHOLE LOCATIONS

14 APPENDIX B Boring Log Key Boring Logs

15 KEY TO BORING LOGS PARTICLE SIZE LIMITS CLAY SILT SAND GRAVEL COBBLES BOULDERS FINE MEDIUM COARSE FINE COARSE.002 mm #200 #40 #10 #4 3/4 inch 3 inch 12 inch USCS GROUP GW GP GM GC SW SP SM SC ML CL OL MH CH OH CS PT TYPICAL SOIL DESCRIPTION Well graded gravels, gravel-sand mixtures, little or no fines Poorly graded gravels, gravel-sand mixtures, little or no fines Silty gravels, poorly graded gravel-sand-silt mixtures Clayey gravels, poorly graded gravel-sand-clay mixtures Well graded sands, gravelly sands, little or no fines Poorly graded sands, gravelly sands, little or no fines Silty sands, poorly graded sand-silt mixtures Clayey sands, poorly graded sand-clay mixtures Inorganic silts and very fine sands, rock flour, silty or clayey fine sands with slight plasticity Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays Organic silts and organic silt-clays of low plasticity Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts Inorganic clays of high plasticity, fat clays Organic clays of medium to high plasticity Claystone/Siltstone Peat and other highly organic soils MOISTURE CONDITION CRITERIA SOIL CEMENTATION CRITERIA Description Criteria Description Criteria Dry Absence of moisture, dusty, Weak Crumbles or breaks with handling or little dry to touch. finger pressure. Moist Damp, no visible free water. Moderate Crumbles or breaks with considerable Wet Visible free water, usually below finger pressure. groundwater table. Strong Won t break or crumble w/finger pressure. Groundwater Elevation Symbols STANDARD PENETRATION CLASSIFICATION * Blow counts on Calif. Modified GRANULAR SOIL CLAYEY SOIL Sampler (N CMS ) can be converted BLOWS/FT DENSITY BLOWS/FT CONSISTENCY to N SPT by: 0-4 VERY LOOSE 0 1 VERY SOFT (N CMS )(0.62) = N SPT 5-10 LOOSE 2-4 SOFT MEDIUM DENSE 5-8 MEDIUM STIFF Blow counts from Automatic or DENSE 9-15 STIFF Safety Hammer can be converted OVER 50 VERY DENSE VERY STIFF to Standard SPT N 60 by: *Standard Penetration Test (N) 140 lb hammer HARD (N AUTOMATIC )(1.30) =N inch free-fall on 2 inch O.D. x 1.4 inch I.D. sampler OVER 60 VERY HARD (N SAFETY )(1.17) =N 60 TEST ABBREVIATIONS SAMPLER NOTATION CD CONSOLIDATED DRAINED O ORGANIC CONTENT CMS CALIF. MODIFIED SAMPLER CH CHEMICAL (CORROSIVENESS) OC CONSOLIDATION CPT CONE PENETRATION CM COMPACTION PI PLASTICITY INDEX CS CONTINUOUS SAMPLER CU CONSOLIDATED UNDRAINED RQD ROCK QUALITY DESIGNATION CSS CALIFORNIA SPLIT SPOON D DISPERSIVE SOILS RV R-VALUE P PUSHED (NOT DRIVEN) DS DIRECT SHEAR S SIEVE ANALYSIS PB PITCHER BARREL E EXPANSIVE SOIL SL SHRINKAGE LIMIT RC ROCK CORE G SPECIFIC GRAVITY U UNCONFINED COMPRESSION SH SHELBY TUBE H HYDROMETER UU UNCONSOLIDATED UNDRAINED SPT STANDARD PENETRATION TEST HC HYDRO-COLLAPSE UW UNIT WEIGHT TP TEST PIT K PERMEABILITY W MOISTURE CONTENT - I.D.= inch - I.D.=3.228 inch with tube; 3.50 inch w/o tube SOIL COLOR DESIGNATIONS ARE FROM THE MUNSELL SOIL COLOR CHART. EXAMPLE: (7.5 YR 5/3) BROWN - NXB I.D.= inch LAST MODIFIED: October 11, I.D.= inch

16 ELEV. (ft) DEPTH (ft) SAMPLE BLOW COUNT 6 inch Last NO. TYPE Increments 1 foot A B SPT SPT EXPLORATION LOG START DATE 6/23/09 END DATE 6/23/09 JOB DESCRIPTION US 93 Wildlife Crossings LOCATION US 93 North of Wells, NV. BORING WC-1 E.A. # GROUNDWATER LEVEL GROUND ELEV (ft) DATE DEPTH ft ELEV. ft HAMMER DROP SYSTEM Automatic Percent Recov'd LAB TESTS USCS Group GC ASPHALTIC CONCRETE (11") BASE (13") STATION OFFSET ENGINEER EQUIPMENT OPERATOR DRILLING METHOD BACKFILLED MATERIAL DESCRIPTION CLAYEY GRAVEL with SAND Dark gray to dark brown, damp, dense. CLAYEY GRAVEL with SAND Medium brown, damp, medium dense. "B" ' Right Boomhower Diedrich D-120 Altamirano 6" H.S.A. Yes DATE SHEET 1 OF 1 Bulk 2.0'-3.5'. 6/23/2009 REMARKS (A) Rock in sampler shoe C SPT SC CLAYEY SAND with GRAVEL Medium brown, damp to wet, medium stiff to stiff D SPT GC CLAYEY GRAVEL with SAND Light to medium brown, damp to wet, loose to medium dense NV_DOT US 93 WILDLIFE CROSSINGS.GPJ NV_DOT.GDT 8/21/ E SPT F CMS G SPT 15/3" 15/3" 0 CL CH SANDY LEAN CLAY Medium brown, damp to wet, stiff to very stiff. FAT CLAY with SAND Medium to dark brown, mottled with light brown silty clay, damp, very stiff. B.O.H. Native 19'. (G) 10 blows - no progress. Bouncing on rock. No sample recovered. 350 psi down pressure for 10 minutes - 6" progress.

17 EXPLORATION LOG START DATE 6/23/09 END DATE 6/23/09 JOB DESCRIPTION US 93 Wildlife Crossings LOCATION US 93 North of Wells, NV. BORING WC-2 E.A. # GROUNDWATER LEVEL GROUND ELEV (ft) DATE DEPTH ft ELEV. ft HAMMER DROP SYSTEM Automatic STATION OFFSET ENGINEER EQUIPMENT OPERATOR DRILLING METHOD BACKFILLED "B" ' Right Boomhower Diedrich D-120 Altamirano 6" H.S.A. Yes DATE SHEET 1 OF 1 6/23/2009 ELEV. (ft) DEPTH (ft) SAMPLE NO. TYPE BLOW COUNT 6 inch Last Increments 1 foot Percent Recov'd LAB TESTS USCS Group MATERIAL DESCRIPTION ASPHALTIC CONCRETE (11") BASE (13") REMARKS WC-2 10' north of WC No samples were taken from this borehole; it was drilled to verify the hard bottom found in borehole WC-1. NV_DOT US 93 WILDLIFE CROSSINGS.GPJ NV_DOT.GDT 8/21/ A SPT 18 25/2" 25/2" SM SILTY SAND Light to medium yellowish brown, dry, cemented, very dense B.O.H. (A) Last 10 blows - 1/4" progress. 350 psi down pressure for 5 minutes - 4.5" progress.

18 ELEV. (ft) DEPTH (ft) SAMPLE BLOW COUNT 6 inch Last NO. TYPE Increments 1 foot A B SPT CMS START DATE 6/23/09 END DATE 6/23/09 JOB DESCRIPTION US 93 Wildlife Crossings LOCATION US 93 North of Wells, NV. BORING WC-3 E.A. # GROUNDWATER LEVEL GROUND ELEV (ft) DATE DEPTH ft ELEV. ft HAMMER DROP SYSTEM Automatic Percent Recov'd LAB TESTS USCS Group EXPLORATION LOG ASPHALTIC CONCRETE (12") BASE (9") STATION OFFSET ENGINEER EQUIPMENT OPERATOR DRILLING METHOD BACKFILLED MATERIAL DESCRIPTION CLAYEY SAND Medium to dark brown, damp, medium stiff. CLAYEY SAND with GRAVEL Medium to dark brown, damp, medium stiff. "X" ' Left Boomhower Diedrich D-120 Altamirano 6" H.S.A. Yes DATE SHEET 1 OF 2 Bulk 2.5'-4.0'. 6/23/2009 REMARKS SC C SPT CLAYEY SAND Medium brown, damp, loose D SPT CL SANDY LEAN CLAY with GRAVEL Medium to dark brown, moist, medium stiff NV_DOT US 93 WILDLIFE CROSSINGS.GPJ NV_DOT.GDT 8/21/ E F G SPT SPT SPT SM CL SILTY SAND with GRAVEL Light to medium yellowish brown, moist, medium stiff. SILTY SAND with GRAVEL Medium brown, moist, stiff. LEAN CLAY with SAND Dark brown, moist to wet, soft. Native 24'.

19 ELEV. (ft) DEPTH (ft) SAMPLE NO. TYPE EXPLORATION LOG START DATE 6/23/09 SHEET 2 OF 2 END DATE 6/23/09 STATION "X" JOB DESCRIPTION US 93 Wildlife Crossings OFFSET 13' Left LOCATION US 93 North of Wells, NV. ENGINEER Boomhower WC-3 Diedrich D-120 BORING EQUIPMENT Altamirano E.A. # GROUNDWATER LEVEL OPERATOR DATE DRILLING GROUND ELEV (ft) DEPTH ft ELEV. ft METHOD 6" H.S.A. HAMMER DROP SYSTEM Automatic BACKFILLED Yes DATE 6/23/ H SPT BLOW COUNT 6 inch Last Increments 1 foot 76 Percent Recov'd 100 LAB TESTS USCS Group MATERIAL DESCRIPTION CLAYEY SAND Olive green, dry, cemented, very stiff. REMARKS I SPT 28 50/4.5" 50/4.5" 100 SC J SPT 20/1.5" 20/1.5" B.O.H. (J) No sample recovered NV_DOT US 93 WILDLIFE CROSSINGS.GPJ NV_DOT.GDT 8/21/

20 EXPLORATION LOG START DATE 6/24/09 END DATE 6/24/09 JOB DESCRIPTION US 93 Wildlife Crossings LOCATION US 93 North of Wells, NV. BORING WC-4 E.A. # GROUNDWATER LEVEL DEPTH ft ELEV. ft GROUND ELEV (ft) DATE 6/24/ HAMMER DROP SYSTEM Automatic STATION OFFSET ENGINEER EQUIPMENT OPERATOR DRILLING METHOD BACKFILLED "X" ' Left Boomhower Diedrich D-120 Altamirano 6" H.S.A. Yes DATE SHEET 1 OF 2 6/24/2009 ELEV. (ft) DEPTH (ft) SAMPLE BLOW COUNT 6 inch Last NO. TYPE Increments 1 foot Percent Recov'd LAB TESTS USCS Group MATERIAL DESCRIPTION ASPHALTIC CONCRETE (10") BASE (8") REMARKS A B SPT SPT SC 4.50 CLAYEY SAND with GRAVEL Medium brown, damp, loose. CLAYEY GRAVEL with SAND Medium brown, damp, medium dense. Bulk 2.5'-5.0' C SPT GC CLAYEY GRAVEL with SAND Medium to dark grayish brown, damp, medium dense D E SPT CMS CLAYEY GRAVEL with SAND Light to medium grayish brown, mottled with rusty reddish orange, dry, medium dense. LEAN CLAY with SAND Dark grayish brown, wet, medium stiff. Native 17'. NV_DOT US 93 WILDLIFE CROSSINGS.GPJ NV_DOT.GDT 8/21/ F SPT CL CH SC SANDY FAT CLAY Reddish orange, wet, stiff. CLAYEY SAND with GRAVEL Medium reddish brown, wet, medium dense.

21 ELEV. (ft) EXPLORATION LOG START DATE 6/24/09 SHEET 2 OF 2 END DATE 6/24/09 STATION "X" JOB DESCRIPTION US 93 Wildlife Crossings OFFSET 13' Left LOCATION US 93 North of Wells, NV. ENGINEER Boomhower WC-4 Diedrich D-120 BORING EQUIPMENT Altamirano E.A. # GROUNDWATER LEVEL OPERATOR DATE DEPTH ft DRILLING GROUND ELEV (ft) ELEV. ft METHOD 6" H.S.A. 6/24/ HAMMER DROP SYSTEM Automatic BACKFILLED Yes DATE 6/24/2009 SAMPLE BLOW COUNT DEPTH 6 inch Last (ft) NO. TYPE Increments 1 foot 7 G SPT Percent Recov'd 115 LAB TESTS USCS Group MATERIAL DESCRIPTION CLAYEY SAND with GRAVEL Medium reddish brown, wet, medium dense. REMARKS Free SC H CMS CLAYEY SAND with GRAVEL Medium reddish brown, wet, very dense I SPT CLAYEY SAND with GRAVEL Medium brown, wet, dense. B.O.H. NV_DOT US 93 WILDLIFE CROSSINGS.GPJ NV_DOT.GDT 8/21/

22 APPENDIX C Soil Particle Size Distribution Sheets Test Result Summary Sheets

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