FINAL GEOTECHNICAL INVESTIGATION BURNS BRIDGE REPLACEMENT COLORADO RIVER ROAD BURNS, COLORADO. December 12, 2012

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1 FINAL GEOTECHNICAL INVESTIGATION BURNS BRIDGE REPLACEMENT COLORADO RIVER ROAD BURNS, COLORADO December 12, 2012 Prepared For: AMEC Environment & Infrastructure 2000 South Colorado Boulevard, Suite Denver, Colorado Prepared By: Yeh and Associates, Inc Blake Avenue Glenwood Springs, CO Phone (970) Fax (970) Project No

2 Burns Bridge Replacement Project No Geotechnical Investigation TABLE OF CONTENTS 1.0 PROJECT INFORMATION Purpose and Scope Proposed Construction Site Conditions Site Geology SITE INVESTIGATION Subsurface Investigation Subsurface Conditions Groundwater Site Grading FOUNDATION RECOMMENDATIONS Bridge Foundation Considerations Driven Steel HPile Drilled Shafts Lateral Earth Pressure BRIDGE APPROACH SETTLEMENT SEISMIC CONSIDERATIONS FOUNDATION CONCRETE AND CORROSIVITY LIMITATIONS LIST OF TABLES Table 1 Bedrock and Estimated Pile Tip Elevations... 6 Table 2 LPILE Program Lateral Loading Parameters... 7 Table 3 Seismic Design Parameters...10 Table 4 Seismic Design Parameters for Site Class D...10 LIST OF FIGURES Figure 1 Approximate Site Location Map Figure 2 Approximate Test Hole Location Map LIST OF APPENDICES Drill Logs, Legend and Core Pictures... A Laboratory Test Results and Summary Table... B i

3 Burns Bridge Replacement Project No Geotechnical Investigation 1.0 PROJECT INFORMATION 1.1 Purpose and Scope This report presents the results of our geotechnical investigation for the design and construction of the bridge replacement across the Colorado River near Burns, Colorado. The project site is located at mile marker 23.5 on Colorado River Road, also known as County Road 301, in Eagle County, Colorado (Figure 1). The purpose of this study was to evaluate general geotechnical characteristics of the onsite soils and rock and provide geotechnical recommendations for the proposed new replacement bridge. The geotechnical investigation consisted of geologic reconnaissance and exploratory test hole drilling to investigate general subsurface conditions. Test hole drilling was observed by a representative of Yeh and Associates. Samples obtained during the field exploration were examined by the project personnel and representative samples were subjected to laboratory testing to determine the engineering characteristics of materials encountered. This report summarizes our field investigation, the results of our analysis and our conclusions and recommendations based on the proposed construction, site reconnaissance, subsurface investigation, and results of the laboratory testing. 1.2 Proposed Construction A new bridge is proposed over the Colorado River to replace the existing Colorado River Road (CR 301) Burns Bridge that was originally constructed in The exact location and size of the proposed bridge were undecided at the time of the drilling investigation. Plans dated November 16, 2012 provided by the client show the structure situated approximately 42 to 53 feet to the south of the existing bridge (centerline to centerline). The proposed structure will be approximately 35 feet wide by 283 feet long and consist of 3 spans. The proposed bridge deck elevation will be approximately 6,486 to 6,491 feet and will be approximately 2 to 7 feet higher than the existing bridge. Based on the plans provided, we estimate fills of up to 15 feet would be necessary for new abutments and approaches. Approximately 576 feet of roadway will be reconstructed for the new approaches and transitions with 260 feet of reconstruction west of the bridge and 316 feet of reconstruction east of the bridge. We understand that pavement design for the approaches will be provided by others. The proposed bridge abutments and piers will 1

4 Burns Bridge Replacement Project No Geotechnical Investigation likely be founded on a deep foundation system, such as driven piles or drilled shafts due to potential river scour. 1.3 Site Conditions The project site was located at the existing Burns Bridge near Burns in Eagle County, Colorado and approximately 20 miles northnorthwest of the Town of Eagle near Mile Post 23.5 on Colorado River Road. Existing grades on Colorado River Road sloped down westerly to the bridge at approximately 6 to 7 percent and sloped up westerly from the bridge at approximately 2 percent. The existing bridge deck grade varied between nearly level to 1 percent. Railroad tracks were approximately 150 feet upslope from the west end of the bridge. Vacant property and residential buildings were located adjacent to the project site. The Colorado River was approximately 200 feet wide in the area of the proposed bridge. The existing Burns Bridge over the Colorado River was approximately 211 feet long by 16 feet wide. River water level was approximately 18.5 feet below the existing bridge deck at the time of our investigation. The existing bridge was a six span steel structure with concrete and steel wall abutments and piers. The existing bridge deck construction consisted of asphalt over wood planking. 1.4 Site Geology The site is located west of, and adjacent to, unincorporated Burns, Colorado where the Burns Bridge crosses the Colorado River on Colorado River Road (C.R. 301), approximately 20 miles northnorthwest of Interstate 70 at Eagle, Colorado. The bridge area lies along the axis and near the northwest end of the Burns Syncline, a structural trough of rock layers, that terminates near Vail, Colorado, to the southeast. Exposed in slope outcrops in the project area were the variegated sandstone, siltstone, mudstone, shale and limestone of the Jurassic age Morrison Formation. Cliff outcrops overlying the Morrison Formation are the gray to yellowtan sandstone of the Jurassic age Dakota Sandstone. Surficial deposits at the site included alluvium, consisting of silt, sand, gravels, cobbles and boulders with interbedded streamchannel and flood plain deposits at and near the river, and colluvium consisting of clay, silt, sand, gravels, cobbles and boulders of locally derived material. Clays and surficial deposits derived from the Morrison Formation may be expansive. 2

5 Burns Bridge Replacement Project No Geotechnical Investigation 2.0 SITE INVESTIGATION 2.1 Subsurface Investigation Four test holes were drilled between November 8 and November 23, Test holes TH1 and TH2 were drilled through the existing bridge deck near anticipated (projected) pier locations. Test holes TH3 and TH4 were drilled near anticipated abutment locations. Test hole depths were drilled between 21 and 49 feet below the existing ground surface level. The exact location and size of the proposed bridge were undecided at the time of the drilling investigation. The locations of the test holes are presented in Figure 2. All test holes were advanced using a CME 55 truck drill rig and alternated odex, rotary, core and 4inch continuous flight auger drilling methods to predetermined depths where a modified California or split spoon sampler was used to record blow counts and obtain samples. Core samples were boxed and transported to the laboratories at Yeh and Associates in Glenwood Springs, Colorado. To perform the modified California penetration resistance tests, a 2.0inch inside diameter sampler was seated at the bottom of the test hole, then driven up to 12 inches with blows of a standard hammer weighing 140 pounds and falling a distance of 30 inches utilizing a cat head hammer (ASTM D1586). The number of blows (Blow Count) required to drive the sampler 12 inches or a fraction thereof, constitutes the Nvalue. The Nvalue, when properly evaluated, is an index of the consistency or relative density of the material tested. Split spoon samples are obtained in the same manner, but with a 1.5inch inside diameter sampler. Test hole logs and legend are presented in Appendix A. An engineering geology sheet with test hole locations will be provided. 2.2 Subsurface Conditions In general, the subsurface conditions in the bridge area consist of 16 to 29 feet of medium dense to very dense sand, gravel and occasional cobbles and boulders over sandstone and shale bedrock. Difficult coring in TH1 destroyed the ream shell at 33 feet where coring operations were stopped. Drilling in TH2 ceased at 21 feet due to core equipment issues. In TH3, odex drilling was attempted to 29 feet when bedrock material was too soft for the hammer to penetrate. Test boring was switched to coring method. Coring began at 29 feet in TH3 and 3

6 Burns Bridge Replacement Project No Geotechnical Investigation was stopped at 33.5 feet when the drill became too plugged to continue. Drilling again resumed in TH3 using 4inch continuous flight auger to refusal at 47 feet. Odex drilling in TH4 was stopped at 30 feet and drilling resumed using rotary drilling to the final depth of 49 feet. Bedrock was encountered at elevations of 6,445 to 6,459 feet, or depths of 16 to 29 feet. The elevation of the bridge deck was considered to be 6,484 feet. Sandstone and claystone bedrock samples were subjected to unconfined compression testing. Test results indicated compressive strengths of 11 and 197 psi for claystone bedrock and 8,220 psi for sandstone bedrock. Two abutment samples were subjected to resistivity, ph, sulfate and chloride testing. See Section 6.0 for chemical test results. In general, the sandstone bedrock was hard to very hard and slightly weathered with some iron staining in fractures. Samplers and SPT tests were not able to advance through this hard bedrock and bounced at many depths where SPT tests were conducted. The claystone bedrock was also hard and slightly weathered with some clay infilling in partings between layers. One sample was taken at the edge of the river bank as a representative scour sample. Testing of the scour sample consisted of 85 percent gravel and was nonliquid and nonplastic. This gravel sample classified as GP (USCS) and as A1a (AASHTO). Results of the laboratory testing are summarized in the Summary of Laboratory Test Results, and are presented in Appendix B Groundwater Groundwater was encountered at estimated elevations of 6,464 and 6,463 feet, or depths of 20 feet and 22 feet in TH3 and TH4, respectively, at the time of drilling. TH1 and TH2 were both drilled from the existing bridge deck at an elevation of approximately 6,484 feet, above the Colorado River into the river bed which was at an elevation of 6,462 feet at test hole TH1 and 6,463 feet at test hole TH2. Variations in groundwater conditions may occur seasonally. The magnitude of the variation will be largely dependent upon the adjacent Colorado River water level, the amount of spring snowmelt, duration and intensity of precipitation, site grading changes, and the surface and subsurface drainage characteristics of the surrounding area. 4

7 Burns Bridge Replacement Project No Geotechnical Investigation 2.3 Site Grading At the time of our investigation, a proposed southeast to northwest alignment was suggested by the client for preliminary design purposes. Based on the plans dated November 16, 2012 provided by the client, we anticipate up to 15 feet of fill would be required for new abutments and approaches. The embankment should be sloped at an angle of 2 horizontal to 1 vertical, or flatter. We believe the materials encountered at this site may be excavated with conventional heavy equipment. All areas requiring fill should be stripped of vegetation, organic soils and debris. Topsoil is not recommended for fill material. Fill should be placed in thin, loose lifts of 8 inches thick or less. The onsite soils free of organic matter, debris and rocks larger than 6 inches can be used in fills. We recommend fill materials be placed in accordance with the Colorado Department of Transportation Standard Specifications for Road and Bridge Construction. Placement and compaction of fill should be observed and tested by a representative of the geotechnical engineer. 3.0 FOUNDATION RECOMMENDATIONS The foundation recommendations contained herein, generally comply with AASHTO for either ASD 1 (Allowable Stress Design) or LRFD 2 (Load Resistance Factor Design). 3.1 Bridge Foundation Considerations Based on the results of our subsurface investigation, we recommend the proposed bridge abutments and piers be supported on either driven Hpile or drilled shaft foundations. The piles or drilled shafts should be founded in bedrock. In addition, boulders may be encountered in overburden materials and would likely require predrilling and/or blasting at pile locations. Our investigation boulders were predominately encountered at depths of 0 to 8 feet. Based on test hole drilling, we estimate the bedrock surface at approximately 16 to 18 feet below grade or 1 AASHTO, (2002). Standard Specifications for Highway Bridges, 17 th Edition, American Association of State Highway and Transportation Officials, Washington, D.C. 2 AASHTO, (2010). AASHTO LRFD Bridge Design Specifications, 5 th Edition, American Association of State Highway and Transportation Officials, Washington, D.C. 5

8 Burns Bridge Replacement Project No Geotechnical Investigation elevations of 6,445 to 6,446 feet for bridge piers and at approximately 26 to 29 feet below grade or elevations of 6,455 to 6,459 feet for abutments. We anticipate driven piles would penetrate 3 to 5 feet into bedrock. If additional penetration is required, we recommend the driven pile locations be predrilled to facilitate bedrock penetration. Groundwater will likely be encountered between elevations of 6,463 and 6,466 feet. Temporary casing would likely be required to facilitate drilled shaft installation. The effects of scour (estimated by others) such as, water loading and reduction of soil support, should be accounted for in the horizontal and axial design of the deep foundations. Generally, the top of the deep foundations is installed below the scour depth. Recommendations for driven piles and drilled shafts are presented below Driven Steel HPile 1. For Allowable Stress Design (ASD) criteria, steel Hpile driven into bedrock may be designed for an axial allowable compressive stress of 9 ksi times the crosssectional area of the pile for Grade 36 steel or 12 ksi for Grade 50 steel. For design of an HP12x53 pile section in axial tension, we recommend using 15 percent of the axial allowable compressive stress plus the weight of the pile for center pier locations and 25 percent for abutments. Other pile sizes should be evaluated. Estimated bedrock elevations and pile tip elevations are shown below: Table 1 Bedrock and Estimated Pile Tip Elevations Location Bedrock Elevation* Estimated Pile Tip Elevation* West Abutment West Pier East Pier East Abutment *Existing bridge deck center assumed at elevation 6484 feet. 2. Using Load Resistance Factor Design (LRFD) criteria, steel Hpile driven into bedrock may be designed for a maximum combined end bearing and skin friction nominal bearing axial compression resistance of 27 ksi for Grade 36 steel or 33 ksi for Grade 50 steel, times the cross sectional area of the pile. The factored bearing resistance is the product of the nominal bearing resistance and the resistance factor. A resistance factor of 0.65 may be used provided that a minimum number of piles are dynamically monitored according to AASHTO Table Resistance Factors for Driven Piles and the driving criteria is established by signal matching at the beginningofrestrike (BOR); otherwise, the resistance factor is The maximum factored resistance should be checked against the structural strength limit state for piling. 6

9 Burns Bridge Replacement Project No Geotechnical Investigation 3. Driven piles should be installed per CDOT Standard Specifications for Road and Bridge Construction, Section 502 (Piling) dated The piles should be driven without damage to a refusal criteria defined as 10 blows per inch into bedrock. A range of acceptable manufacturer rated hammer energies should be specified in the Contract per CDOT Section (a) (3.) that are based on Wave Equation Analyses. Yeh and Associates, Inc. can provide these analyses once a pile size and type has been determined. 4. Based on the results of our field exploration, laboratory testing and our experience with similar properly constructed driven pile foundations, we estimate individual pile settlement will be less than ½ inch when designed according to the criteria presented in this report. 5. The upper 3 feet of pile penetration should be neglected for lateral load resistance calculation. For lateral loading analysis using LPILE program, the following parameters may be used: Material Table 2 LPILE Program Lateral Loading Parameters Soil Model Friction Angle, φ (deg) Cohesion, c (psf) Horizontal Modulus of Subgrade Reaction, k h (pci) ε 50 Effective Unit Weight, γ (pcf) Saturated Unit Weight, γ (pcf) Structural Reese Fill Sand Sand above Reese groundwater Sand Sand and gravel Reese below Sand groundwater Bedrock Stiff Clay Groups of piles will also require appropriate reductions of the lateral capacities based on shadowing and other group effects. The minimum spacing requirements between piles should be three diameters from center to center. For lateral loading, recommended P multipliers should comply with AASHTO LRFD Table to account for lateral group effects. Reductions for axial capacities are not necessary for piles driven to bedrock through granular soil at three diameter spacing or greater. 7. Steel reinforcement pile tips are required on the ends of the steel HP sections for protection. 7

10 Burns Bridge Replacement Project No Geotechnical Investigation Drilled Shafts 1. For Allowable Stress Design (ASD) criteria, drilled shafts embedded in the hard bedrock may be designed for an allowable end bearing pressure of 60 ksf and a skin friction of 6 ksf for the portion of drilled shaft in bedrock. 2. Using Load Resistance Factor Design (LRFD) criteria, an end bearing nominal bearing capacity of 180 ksf and a nominal side shear capacity of 18 ksf for that portion of the drilled shaft embedded into bedrock may also be used. We recommend resistance factors of 0.60 and 0.55 for side shear and end bearing, respectively. Settlement of the structure using the LRFD method should be checked against loadings obtained based on service limit state. 3. Drilled shafts should penetrate a minimum of 5 feet into bedrock or 2 times the shaft diameter, whichever is greater. 4. Bedrock may be very hard at various elevations and vary in consistency from claystone to shale to sandstone. The contractor should mobilize equipment of sufficient size and operating condition to achieve the required design bedrock penetration. 5. The upper 3 feet of drilled shaft penetration should be neglected for lateral load resistance calculation. For lateral loading analysis using LPILE program, the parameters from Table 2 of the Driven Steel HPile Section may be used. 6. The minimum spacing requirements between drilled shafts should be three diameters from center to center. For consideration of group effects the recommendations in item 6 of the driven Steel Hpile Section may be used. Additional capacity reduction factors can be provided if required for conditions other than those anticipated. 7. The presence of water in the exploratory test holes indicates casing and/or dewatering equipment will be required. In no case should concrete be placed in more than 3 inches of water unless the tremie method is used. If water cannot be removed or prevented with the use of casing and/or dewatering equipment prior to placement of concrete, the tremie method, as described in the CDOT s 2011 Standard Specifications for Road and Bridge Construction, should be used. 8. A representative of the soils engineer should observe drilled shaft drilling operations on a fulltime basis. 3.2 Lateral Earth Pressure Bridge retaining/wing walls should be designed to resist lateral earth pressure. We recommend all retaining/wing walls are backfilled with CDOT Class 1 Structure Backfill. Walls can be designed using an equivalent fluid density of 35 pcf for active or 55 pcf for at rest conditions for 8

11 Burns Bridge Replacement Project No Geotechnical Investigation Class 1 Structure Backfill. This equivalent fluid density assumes a horizontal slope above the wall. This value also assumes that the backfill materials are not saturated. Wall designs should consider the influence of surcharge loading such as traffic, construction equipment and/or sloping backfill. Retaining/wing walls should be constructed with a drainage system to drain away any excess water immediately behind the wall. The drainage system may consist of freedraining gravel, pipes, drain board and/or weep holes are commonly used for the wall drainage. 4.0 BRIDGE APPROACH SETTLEMENT Based on subsurface conditions, anticipated abutment elevation and our experience, we believe that potential settlement of bridge approaches would be minor. Subsoils below the bridge approaches consisted of medium to very dense sands with gravels, cobbles and boulders. We believe these materials would exhibit low consolidation after placement of new fill at the approaches. We estimate fill depths of up to 15 feet for bridge approaches. Total settlement of less than 1inch should be anticipated. 5.0 SEISMIC CONSIDERATIONS The project is located at approximate latitude and longitude The site is classified as Site Class D in accordance with Table of the AASHTO LRFD Bridge Design Specifications. The Peak Ground Acceleration (PGA), and the short and longperiod spectral acceleration coefficients (Ss and S1 respectively) for the Burns bridge site were obtained using the USGS 2007 Seismic Parameters for an event with a 7% Probability of Exceedance (PE) in 75 years and a Site Class B (reference site). An event with the above probability of exceedance has a return period of about 1,000 years. The values were adjusted using Site Factors for Site Class D in accordance with Section of the AASHTO LRFD Bridge Design Specifications. The seismic parameters for this site are shown on the tables below. 9

12 Burns Bridge Replacement Project No Geotechnical Investigation Table 3 Seismic Design Parameters PGA (0.0 sec) Ss (0.2 sec) S1 (1.0 sec) Table 4 Seismic Design Parameters for Site Class D As (0.0 sec) SDs (0.2 sec) SD1 (1.0 sec) Seismic Zone g g g FOUNDATION CONCRETE AND CORROSIVITY The concentrations of watersoluble sulfates measured in the laboratory on the near surface samples varied from and percent in test holes TH4 and TH3, respectively. These concentrations of watersoluble sulfates represent a negligible/low (Class 0 exposure) degree of sulfate attack on concrete exposed to these materials. The degree of attack is based on a range of 0.00 to less than 0.10 percent as presented in the American Concrete Institute Guide to Durable Concrete. Due to the negligible/low degree indicated by the test results, no special requirements for concrete are necessary for Class 0 exposure. The ph and electrical resistivity was determined for selected samples. Test results measured ph values at 6.8 and 7.4 in test holes TH4 and TH3, respectively. Resistivity measurements were 513 and 1083 ohmcentimeters and watersoluble chlorides were and percent in test holes TH4 and TH3, respectively. A qualified corrosion engineer should review this data to determine the appropriate level of corrosion protection. 7.0 LIMITATIONS This study was conducted in accordance with generally accepted geotechnical engineering practices in this area for use by the client for design purposes. The conclusions and recommendations submitted in this report are based upon the data obtained from exploratory test holes, field reconnaissance and anticipated construction. The nature and extent of subsurface variations across the site may not become evident until excavation is performed. If during construction, conditions appear to be different from those described herein; this office should be advised at once so reevaluation of the recommendations may be made. We 10

13 Burns Bridge Replacement Project No Geotechnical Investigation recommend onsite observation of excavations by a representative of the geotechnical engineer. The scope of services for this project did not include, specifically or by implication, any environmental or biological (e.g., mold, fungi, and bacteria) assessment of the site or identification or prevention of pollutants, or conditions or biological conditions. If the owner is concerned about the potential for such contamination, conditions or pollution, other studies should be undertaken. A hazardous material evaluation is to be provided in a separate report. The report was prepared in substantial accordance with the generally accepted standards of practice for geotechnical engineering as exist in the site area at the time of our investigation. No warranties, express or implied, are intended or made. Respectfully Submitted: YEH AND ASSOCIATES, INC. Reviewed by: Keith E. Asay Staff Engineer Richard D. Johnson, P.E. Project Manager Paul Macklin, P.E. Principal Engineer 11

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16 Burns Bridge Replacement Project No Geotechnical Investigation APPENDIX A Drill Logs, Legend and Core Pictures

17 TH4 West abutment boring Elevation: 6485 ft TH3 East abutment boring Elevation: 6484 ft 6,480 ph= 6.8 S= % Re= 513ohmscm ph= 7.4 S= 0.014% Re= 1083ohmscm 6,480 6,470 23/12 TH1 West pier boring Elevation: 6462 ft TH2 East pier boring Elevation: 6463 ft 19/12 6,470 50/0 6,460 6,460 6,450 50/0 83%/0 36/12 80%/47% 100%/0 6,450 Elevation (ft) 6,440 6,430 6,420 50/0 50/0 76%/11% 100%/63% 72%/45% 60%/0 DD= 165.0pcf UCCS= psf MC= 12% DD= 117.0pcf LL= 33 PL= 21 UCCS= 1535psf MC= 11% DD= 115.0pcf LL= 29 PL= 20 MC= 3% DD= 146.0pcf UCCS= 28319psf 50/0 50/0 6,440 6,430 6,420 FENCES BY ELEVATION A SIZE BORING LOGS.GPJ RDJ.GDT 12/6/12 6,410 6,400 6,390 YEH AND ASSOCIATES, INC. GEOTECHNICAL ENGINEERING CONSULTANTS Project Number: Burns Bridge Replacement 6,410 6,400 6,390 Figure No. A1

18 YEH AND ASSOCIATES, INC. GEOTECHNICAL ENGINEERING CONSULTANTS Project: Burns Bridge Replacement Project Number: Legend for Symbols Used on Borehole Logs Sample Types Bulk sample was obtained from auger cuttings at the depths indicated. Rock Core. The symbol 76%/11% indicates 76% recovery in core barrel and a Rock Quality Designation (RQD) of 11% for the length of core shown. Modified California Sampler. The symbol 16/12 indicates that 16 blows from a 140 pound hammer falling 30 inches was used to drive 2inch I.D. sampler 12 inches. Other Symbols Indicates practical drill rig refusal. Indicates approximate groundwater or river depth and elevation at time of drilling. Indicates approximate groundwater or river depth and elevation on December 4, Soil Lithology GRAVEL, sandy, interlayered with cobbles and boulders. See detailed, graphical drill logs. SAND, gravelly with cobbles and boulders. See detailed, graphical drill logs SAND, silty. See detailed, graphical drill logs. SILT, sandy. See detailed, graphical drill logs. Bedrock Lithology CLAYSTONE, sandy, slightly moist, hard to very hard, brown, red, olive. SANDSTONE, slightly moist, hard to very hard, brown, tan, redbrown. Lab Test Abbreviations MCMoisture Content DDDry Density LLLiquid Limit PLPlastic Limit UCCSUnconfined Compressive Strength SWater Soluble Sulfates ReResistivity NOTES: 1. Test holes were odexed, cored and/or drilled with 3 and 4inch continuous flight auger on November 9, 10, 15 and 16, Test hole descriptions are subject to explanations contained in this report. 3. Existing bridge deck at center point elevation estimated 6,484 feet based on topographic map by others. Figure No. A2

19 YEH AND ASSOCIATES, INC. GEOTECHNICAL ENGINEERING CONSULTANTS Project: Burns Bridge Replacement Project Number: Boring: TH1 Sheet 1 of 1 Boring Began: 11/9/2011 Drilling Method: Odex and Core Drill: CME 55 Driller: Ager Drilling Logged By: K. Asay Final By: K. Asay Inclination: Vertical Ground Water Notes: Drill river bed Depth Date Time Completed: 11/9/2011 Drill Bit: NX Casing: Steel Casing Weather: Clear, cold 3.5 ft 11/9/ ft 12/4/12 Total Depth: 33.0 ft Ground Elevation: ft Location: West pier boring Coordinates: N: 1.0 E: 2.0 Elevation (feet) Depth (feet) Run / Sample Type Recovery (%) Rock RQD Soil Samples SPT Blows per 6 in N Lithology Material Description Field Notes and Lab Tests ft. silty SAND, brown, wet, (alluvium). Began odex drilling in river bed ft. sandy GRAVEL with cobbles, brown, wet, (alluvium) ft. silty SAND, brown, wet, (alluvium) ft. sandy SILT, brown, wet, (alluvium) ft. SANDSTONE BEDROCK, gray, very hard, joint, joint spacing close, open fractures, iron stains, smooth surfaces, (MORRISON FORMATION). Odex in bedrock at 16 feet. BORING LOG BORING LOGS.GPJ RDJ.GDT 12/6/ ft. CLAYSTONE BEDROCK, gray, hard, parting clay infilling, (MORRISON FORMATION) ft. Plugged off. Ream shell destroyed at 33 feet. Drilling ceased.. Bottom of Hole at 33.0 ft. Switch to coring in bedrock at 21 feet. DD= 165.0pcf UCCS= psf 18 minutes to drill 1.5 feet. MC= 12% DD= 117.0pcf LL= 33 PL= 21 UCCS= 1535psf 8 minutes to drill 2.5 feet. MC= 11% DD= 115.0pcf LL= 29 PL= minutes to drill 4 feet. Plugged 28 feet. MC= 3% DD= 146.0pcf UCCS= 28319psf 35 minutes to drill 4 feet.

20 YEH AND ASSOCIATES, INC. GEOTECHNICAL ENGINEERING CONSULTANTS Project: Burns Bridge Replacement Project Number: Boring: TH2 Sheet 1 of 1 Boring Began: 11/10/2011 Drilling Method: Odex Drill: CME 55 Driller: Ager Drilling Logged By: K. Asay Final By: K. Asay Inclination: Vertical Ground Water Notes: Drill river bed Depth Date Time Completed: 11/10/2011 Drill Bit: Casing: Steel Casing Weather: Clear, cold 2.5 ft 11/10/ ft 12/4/12 Total Depth: 21.0 ft Ground Elevation: ft Location: East pier boring Coordinates: N: 1.0 E: 3.0 Elevation (feet) Depth (feet) Run / Sample Type Recovery (%) Rock RQD Soil Samples SPT Blows per 6 in N Lithology Material Description Field Notes and Lab Tests ft. silty SAND, brown, wet, (alluvium). Started odex drilling in river bed ft. gravelly SAND with silt, brown, wet, (alluvium) ft. sandy GRAVEL with cobbles and boulders, brown, wet, (alluvium). Cobbles and boulders up to 18 inch diameter ft. gravelly SAND with silt, cobbles and boulders, brown, wet, (alluvium) ft. sandy GRAVEL boulders, brown, wet, (alluvium). Boulders up to 18 inch diameter ft. silty SAND, brown, wet, (alluvium) ft. SANDSTONE BEDROCK, gray, very hard, (MORRISON FORMATION). BORING LOG BORING LOGS.GPJ RDJ.GDT 12/6/ Bottom of Hole at 21.0 ft. Stopped odex to switch to coring at 21 feet. Drill required new parts before coring. Coring abandoned for this test hole.

21 YEH AND ASSOCIATES, INC. GEOTECHNICAL ENGINEERING CONSULTANTS Project: Burns Bridge Replacement Project Number: Boring: TH3 Sheet 1 of 2 Boring Began: 11/15/2011 Drilling Method: Odex, Core and Auger Drill: CME 55 Driller: Ager Drilling Logged By: S. White Ground Water Notes: Final By: S. White Depth Date Inclination: Vertical Time Elevation (feet) Depth (feet) Run / Sample Type Recovery (%) Rock RQD Soil Samples SPT Blows per 6 in Completed: 11/17/2011 Drill Bit: NX Casing: Steel Casing Weather: Clear, cold N 20.0 ft 11/15/11 Lithology Material Description Total Depth: 47.0 ft Ground Elevation: ft Location: East abutment boring Coordinates: N: 1.0 E: 4.0 Field Notes and Lab Tests ft. sandy GRAVEL with cobbles and boulders, brown, slightly moist, dense to very dense, (alluvium/colluvium). Odex drilling started at surface. ph= 7.4 S= 0.014% Re= 1083ohmscm ft. gravelly SAND with silt, cobbles and boulders, brown, slightly moist, medium dense, (alluvium/colluvium). Boulders and cobbles up to 24 inches diameter encountered in first 5 feet /12 Drilling stopped for repair of shoe for odex at 10 feet ft. silty SAND with gravels, brown, slightly moist to wet, medium dense, (alluvium/colluvium). Drilling fast in soft materials to 20 feet Driller couldn't get bit to release from casing at 20 feet. Drilling continued in soft material BORING LOG BORING LOGS.GPJ RDJ.GDT 12/6/ / ft. SANDSTONE BEDROCK, gray, very hard, open fractures, iron stains, smooth surfaces, (MORRISON FORMATION) ft. CLAYSTONE BEDROCK, gray, hard, (MORRISON FORMATION). At 29 feet, material too soft for odex hammer. Changed to coring. Core bit plugging at 34 feet. Changed to auger drilling. Auger refusal.

22 YEH AND ASSOCIATES, INC. GEOTECHNICAL ENGINEERING CONSULTANTS Project: Burns Bridge Replacement Project Number: Boring: TH3 Sheet 2 of 2 Elevation (feet) Depth (feet) Run / Sample Type Recovery (%) Rock RQD Soil Samples SPT Blows per 6 in N Lithology Material Description Field Notes and Lab Tests ft. (CLAYSTONE BEDROCK continued, MORRISON FORMATION). Driller retried auger and drilled to 47 feet / /0 Bottom of Hole at 47.0 ft. Auger refusal BORING LOG BORING LOGS.GPJ RDJ.GDT 12/6/

23 YEH AND ASSOCIATES, INC. GEOTECHNICAL ENGINEERING CONSULTANTS Project: Burns Bridge Replacement Project Number: Boring: TH4 Sheet 1 of 2 Boring Began: 11/16/2011 Drilling Method: Odex and Rotary Drill: CME 55 Driller: Ager Drilling Logged By: S. White Final By: S. White Inclination: Vertical Elevation (feet) Depth (feet) Run / Sample Type Recovery (%) Rock RQD Ground Water Notes: Depth Date Time Soil Samples SPT Blows per 6 in Completed: 11/16/2011 Drill Bit: Casing: Steel Casing Weather: Clear, cold N 22.0 ft 11/16/11 Lithology Material Description Total Depth: 49.0 ft Ground Elevation: ft Location: West abutment boring Coordinates: N: 1.0 E: 1.0 Field Notes and Lab Tests ft. gravelly SAND with silt, cobbles and boulders, brown and rust, slightly moist, medium dense, (alluvium/colluvium). ph= 6.8 S= % Re= 513ohmscm / ft. sandy GRAVEL and BOULDERS, brown, slightly moist, very dense, (alluvium/colluvium) ft. gravelly SAND with silt, cobbles and boulders, brown and rust, slightly moist to wet, medium dense, (alluvium/colluvium). Approximate 4 foot diameter boulder encountered at depth of 3.5 feet. Up to 24 inch diameter cobbles and boulders encountered. Drill head jammed at 10 feet. Stopped for repair. No cuttings return available for sampling from odex drilling from 10 to 20 feet / ft. silty SAND with clay, few gravels, brown, wet, (alluvium/colluvium). BORING LOG BORING LOGS.GPJ RDJ.GDT 12/6/ / ft. SANDSTONE BEDROCK, gray, very hard, (MORRISON FORMATION) ft. CLAYSTONE BEDROCK, gray, medium hard to hard, (MORRISON FORMATION). Changed to rotary drilling at 30 feet.

24 YEH AND ASSOCIATES, INC. GEOTECHNICAL ENGINEERING CONSULTANTS Project: Burns Bridge Replacement Project Number: Boring: TH4 Sheet 2 of 2 Elevation (feet) Depth (feet) Run / Sample Type Recovery (%) Rock RQD Soil Samples SPT Blows per 6 in N Lithology Material Description Field Notes and Lab Tests ft. (CLAYSTONE BEDROCK continued, MORRISON FORMATION) / /0 Bottom of Hole at 49.0 ft BORING LOG BORING LOGS.GPJ RDJ.GDT 12/6/

25 Drill Core from test hole TH1 at 21 feet to 31 feet Drill Core from test hole TH1 at 31 feet to 33 feet

26 Drill Core from test hole TH3 at 29 feet to 33.5 feet

27 Burns Bridge Replacement Project No Geotechnical Investigation APPENDIX B Laboratory Test Results and Summary Table

28 Sieve Analysis Hydrometer Analysis Sieve Opening in Inches U.S. Standard Sieves Size of Particles in mm " 6" 3" 2" 1" 3/4" 1/2" 3/8" Sieve Size 3" % Passing ½" " ½" 55 Percent Passing " ¾ " ½" ⅜" # # # Particle Size (mm) #200 3 Gravel (%) Sand (%) Fines (%) 3 PI NP Sample Description: LL PL NL NP Gravel with sand (GP) Project Name: Sample ID: Sample Depth (ft.): Burns Bridge Replacement Streambed 0 Drawn By: Checked By: Yeh & Associates, Inc. Geotechnical Engineering Consultants SIEVE ANALYSIS SW RDJ Project No.: Figure No.: B1 Revised 04/22/2004

29 YEH & ASSOCIATES, INC Summary of Laboratory Test Results Project No: Project Name: Burns Bridge Replacement Sample Location Grain Size Analysis Atterberg Limits Water Water Unconfined Moisture Dry Gravel Fines Soluble Soluble Resistivity Compressive Test Sample Content Density Sand ph Soil Description Depth (ft) > #4 < #200 LL PL PI Sulfate Chloride (ohmcm) Strength Hole Type (%) (pcf) (%) (%) (%) (%) (%) (psf) (psi) Stream 0 Bulk NL NP NP Gravel with sand (GP) bed TH Core 165 1,183, Sandstone Bedrock Core , Claystone Bedrock Core Claystone Bedrock Core , Claystone Bedrock TH3 010 Bulk Sand, gravelly with silt TH4 010 Bulk Sand, gravelly with silt NL Indicates nonliquid NP Indicates nonplastic Page 1 of 1