Final_Geotech_Report_Feb-2015.pdf

PERALTA WASH BRIDGE

Cochiti Pueblo Route 85, Sandoval County

NM IRR 85(1)

FINAL GEOTECHNICAL REPORT

Report No. NM-BX-0085-15-01

Geotechnical Services Branch February 2015

Peralta Wash Bridge NM IRR 85 (1) February 2015

Table of Contents

SECTION ONE--INTRODUCTION

1.1 OBJECTIVE AND SCOPE

1.2 PROPOSED CONSTRUCTION

1.3 SITE CONDITIONS

SECTION TWO--GEOLOGY AND SEISMICITY

2.1 GEOLOGY

2.2 GEOLOGIC HAZARDS

2.3 SEISMICITY

2.4 SEISMIC DESIGN PARAMETERS

SECTION THREE--SUBSURFACE INVESTIGATION

3.1 FIELD EXPLORATION AND LABORATORY TESTING PROGRAM

SECTION FOUR--ANALYSIS AND RECOMMENDATIONS

4.1 GEOTECHNICAL PROFILE

4.2 GROUNDWATER AND SOIL MOISTURE CONDITIONS

4.3 BRIDGE FOUNDATION DESIGN

4.3.1 Drilled Shaft Foundation Design

4.3.2 Abutment Design

4.4 EMBANKMENTS

4.5 TEMPORARY CUT SLOPES

4.6 CORROSION POTENTIAL

4.7 CONSTRUCTION CONSIDERATIONS

4.8 LIMITATIONS

SECTION FIVE -- REFERENCES

TABLES

TABLE 1:- Fault and Seismicity Data TABLE 2:- Summary of Seismic Parameters Corrected for Site Class D TABLE 3:- Summary of Design Response Spectrum Data for Site Class D TABLE 4:- Summary of Borings TABLE 5:- N1(60) Calculation for Overburden Material TABLE 6:- Estimated Subsurface Material Parameters for design of Bridge Abutments TABLE 7:- Estimated Subsurface Material Parameters for design of Bridge Piers TABLE 8:- Groundwater Levels TABLE 9:- Resistance Factors for Drilled Shaft Design TABLE 10:- Normalized Load Transfer Values for Drilled Shaft Design TABLE 11:- Recommended Number of Access Tubes vs. Shaft Diameter TABLE 12:- Lateral Earth Pressures for Bridge Abutments

Peralta Wash Bridge NM IRR 85 (1) February 2015

ILLUSTRATIONS

ILLUSTRATION 1:- Design Response Spectrum Corrected for Site Class D

FIGURES

FIGURE 1:- Regional Location Map, Cochiti, Pueblo, Albuquerque FIGURE 2:- Local Area Map, Peralta Wash Bridge FIGURE 3:- Engineering Geology / Boring Logs FIGURE 4:- Geologic Map of the Cochiti Pueblo Area, New Mexico (FIGURE 4 / DETAIL A)

APPENDICES

APPENDIX A - Field Exploration Program APPENDIX B - Laboratory Test Results APPENDIX C - Analysis APPENDIX D - Photos

Peralta Wash Bridge NM IRR 85 (1) 3 February 2015

SECTION ONE--INTRODUCTION

This report presents the results of the geotechnical study conducted for the Peralta Wash Bridge, NM IRR 85(1) project. The project is for the design and construction of a new bridge over Peralta Creek located on Pueblo Route 85 just south of the community of Pueblo de Cochiti and north of the community of Sile. This route serves as the primary access road for the residents of Sile. The new bridge is proposed to accommodate large flood events anticipated from the watershed damage sustained during the 2011 Las Conchas Fire. The fire consumed 28 of the 45 square miles in the upper watershed of Peralta Creek [1]. The watershed damage includes a reduction in the infiltration rates of precipitation and has resulted in flood events even during moderate storm events.

Following the fire, the Pueblo de Cochiti closed the road and removed the two, 10-foot diameter barrel culverts and associated embankments to improve conveyance capacity to safely pass large post-fire flows. Emergency vehicles and local residents cross Peralta Wash by means of a temporary road of loosely-compacted ground at grade within the channel bottom. The temporary crossing is located approximately 100-feet upstream of the closed road.

The Peralta Wash Bridge site location is shown on Figure 1, Regional Location Map. The general location of the project with respect to existing facilities is shown on Figure 2, Local Area Map.

1.1 OBJECTIVE AND SCOPE

The objectives of this study are specifically to provide recommendations concerning bridge foundations, abutment wall earth pressures, embankment stabilization, corrosion potential, and construction considerations. In accomplishing these objectives, the scope of work included field subsurface exploration, laboratory testing, correlation of available data, and geotechnical analysis.

The field exploration included borings at foundation locations and site reconnaissance.

Recommendations are based on the 30% Design Plans [2].

1.2 PROPOSED CONSTRUCTION

Central Federal Lands Highway Division (CFL) of the Federal Highway Administration in coordination with Pueblo de Cochiti and Bureau of Indian Affairs decided that the proposed structure at the Peralta Wash crossing should consists of a three-span pre-stressed girder bridge approximately 250-feet long and 31-feet wide with a cast in-place reinforced concrete deck [3]. The new construction follows existing alignment, grade, and width from Station 5+85 to Station 19+13.

Proposed Abutments 1and 2 are located at Station 9+99.25 and Station 12+42.75 respectively with centerline elevations of 5277.02 at Abutment 1 and 5278.28 at Abutment 2. Piers 1 and 2 are located at Station 10+78.50 and Station 11+63.50, respectively. The channel invert elevation for the Peralta Creek at the centerline of the proposed bridge is approximately 5259.0 feet. The proposed bridge is to accommodate the anticipated scour elevations of 5243.5 feet at the abutments and 5235.8 feet at the piers.

Peralta Wash Bridge NM IRR 85 (1) 4 February 2015

Bridge length was determined based on a 180-foot wide channel bottom with spill through abutments and 2:1 side embankment slopes. The channel bottom width was estimated to accommodate all potential channel instabilities, i.e. potential lateral migration and vertical degradation including failure of the existing gabion grade control structure. A detailed layout of the proposed bridge with respect to site topography based on the 30% design plans, along with boring profile completed for this study, are presented on Figure 3, Boring Logs Map.

1.3 SITE CONDITIONS

The proposed bridge site is located on a large, sparsely vegetated, alluvial fan that slopes to the southeast from the Jemez Mountains to the Rio Grande River. The region consists mainly of alluvial sands and gravels with varying percentages of silt, cobbles and boulders. The cut banks of Peralta Wash vary from gently sloping to vertical with a braded channel bottom at low flows. The wash is generally dry except during and shortly after storm events.

Site accessibility is adequate. Approximately 15 miles from I-25 to project site consists of relatively flat terrain with occasional mild curves, and is close proximity to precast concrete plants in Santa Fe and Albuquerque. The roadway (PR 85) generally consists of two 11-foot paved lanes with one-foot shoulders for a total roadway width of about 24 feet. Locations with existing guardrail have an additional two foot shy distance beyond the shoulder to the face of rail. Width from face of guardrail to face of guardrail was measured at 29 feet adjacent to the failure area.

Although there was no evidence of utilities within the immediate bridge vicinity, a sewer line reportedly is buried downstream of the bridge.

Since the fire, the flow rates within the Peralta Creek have increased dramatically even for normal rainfall events. The Bureau of Land Management (BLM) constructed temporary berms to prevent flood water from reaching Pueblo de Cochiti; although the berms have been effective, severe erosion and undermining by the flows requires continuous maintenance. Due to local residence concerns regarding potential flooding, the two existing 10 foot metal culverts at the proposed bridge crossing were removed in July 2012. Additionally, the roadway embankment serving as an integral part of the existing grade control structure was armored with riprap. When the culverts were removed, the riprap enclosed wire gabion baskets were left as the only grade control. Few months after the culverts were removed, flows from precipitation events unraveled portions of the gabion baskets.

During the summer of 2014, the BIA and local tribe completed additional work in the proposed bridge location. The work included widening channel on the downstream end from 45 feet to approximately 90 feet; installing revet mattresses; applying shotcrete extending 7 feet vertically along the banks; installing cutoff walls (2 feet by 6 feet by 120 feet) upstream of the crossing; and installing gabion baskets (18 feet by 92 feet) [3].

Currently, local residents, including emergency vehicles, cross Peralta Creek using a temporary one-lane road of loosely compacted gravel at grade within the channel bottom located approximately 100 feet north of the closed road.

Peralta Wash Bridge NM IRR 85 (1) 5 February 2015

SECTION TWO--GEOLOGY AND SEISMICITY

2.1 GEOLOGY

Peralta Wash is located within the northern Santo Domingo basin along the Rio Grande and is part of the southern Rocky Mountains geologic province. This province extends from the southern Rocky Mountains in Colorado to the Sierra Madre Occidental in Mexico. The northern Santo Domingo basin extends south from southern White Rock Canyon, where it is bounded by Jemez Mountains to the west and the La Bajada escarpment to the east. The geologic, geophysical, and hydrogeologic properties of the La Bajada constriction and Santo Domingo Basin, northern New Mexico, result from tectonic and volcanic processes of the late Tertiary and Quaternary Rio Grande rift. Several episodes of volcanic eruption, faulting, and erosion have altered the surrounding landscape over a period of millions of years. Illustrated geology at the project site is displayed on Figure 4. [4]

The Santo Domingo basin represents a complex transitional zone between the Albuquerque basin to the southwest and the Espanola basin to the northeast. Erosion of the basin has exposed mainly late Cenozoic sedimentary rocks and sediment deposited by the ancestral Rio Grande and by channels draining sediments to the east and west. Interlayered with the sediments are the Pliocene and early Pleistocene basalts and other volcanic rocks derived from Cerros del Rio volcanic field and the Valles Caldera in the Jemez Mountains. During Quaternary time, the Rio Grande cut the modern White Rock Canyon, transporting large quantities of sediment into the Santo Domingo basin. These sediments are the upper part of the Santa Fe group.

The geology at the bridge site consisted mainly of alluvial sands and gravels with varying percentages of silt, cobbles and boulders. The gravels, cobbles and boulders are primarily of volcanic origin derived mainly from Jemez Mountains to the west. Boulders up to 2.5-foot are present in the stream channel in the vicinity of the bridge site. In addition, there are imported boulders (riprap) of volcanic origin up to 4-foot present within the area of the proposed wash from previous emergency repairs to the existing embankment due to flood damage. A description of the soil encountered from the borings is discussed in more detail in Appendix A.

2.2 GEOLOGIC HAZARDS

Geologic hazards that exist in the vicinity of the project area are flash floods, highly erodible, loose granular soils, slope instability, and seismic events. The severity of the fire in the upper watershed significantly reduced the ability of the soil to allow the rainfall to infiltrate, resulting in increased runoff and reduced lag time between the peak precipitation and the peak runoff. Average precipitation events now initiate large flood events with magnitudes formerly seen only after large rainfall events. The risk is particularly high during the summer monsoon season.

Although primarily outside the area of construction, the over-steepened to vertical cut banks of Peralta Wash may fail or produce rock fall at any time, with an increased likelihood of failure with construction equipment vibrations.

Peralta Wash Bridge NM IRR 85 (1) 6 February 2015

2.3 SEISMICITY

Earthquake damage can be direct or indirect damage. Direct damage is due to strong shaking and fault rupture that occur mainly along faults in close proximity to the site during an earthquake. The closest active faults to the project are listed in Table 1, Fault and Seismicity Data [5].

TABLE 1: – Fault and Seismicity Data

The Pajarito fault zone [6] offsets early Quaternary volcanic rocks and younger alluvium on the west flank of the Pajarito plateau. Surface and subsurface data are lacking for this fault.

La Bajada fault forms the margin between the Santo Domingo basin and the eastern edge of the Rio Grande rift, and truncates the western edge of the Cerros del Rio volcanic field. The fault has been active in the Quaternary because it cuts upper Pliocene and lower Pleistocene volcanic rocks northeast of Cochiti Dam. However, the fault trace is commonly covered by extensive toreva block landslides, and no fault scarps in surficial deposits have been found. These relations indicate an active period of faulting in the latest Pliocene and early Pleistocene, perhaps associated in part with volcanic activity in the Jemez and Cerros del Rio volcanic fields. The fault appears to have been quiescent for the last several hundred thousand years.

The San Francisco fault extends from Cochiti Pueblo south to Placitas. The fault exhibits down-to-the-west normal separation of Miocene rift-fill sediments. The San Francisco fault has west-down normal displacement and traverses the Santo Domingo basin of the Rio Grande rift; sub parallel to the La Bajada fault. The northern end of the San Francisco fault has a complex intersection with the Pajarito fault near Cochiti Lake. The southern end intersects or merges with the Rincon fault and other faults in a complex transition zone near the town of Placitas. No paleo-seismic studies have been completed along the San Francisco fault yet.

2.4 SEISMIC DESIGN PARAMETERS

The American Association of State Highway and Transportation Officials (AASHTO) criteria for seismic design of ordinary bridges, allows for damage to occur when the structure is subjected to 1000-year strong ground motion, but does not allow for collapse of one or more spans and loss of life. Bridges may suffer damage that requires repair or partial replacement. AASHTO; however, requires bridges to withstand small, more frequent earthquakes without damage. For Extreme Event I Limit State Design an earthquake load and resistance factor of 1.00 should be used during the LRFD design of the bridge structure.

Fault Name Maximum Moment Magnitude (Mmax)

Style of Faulting

Fault Dip Fault

Direction Distance in Miles

Pajarito 7.05 Normal 50/65/35 E 4.63

La Bajada 6.96 Normal 50/65/35 W 5.42

San Francisco 6.76 Normal 50/65/35 W 8.15

Peralta Wash Bridge NM IRR 85 (1) 7 February 2015

Recommended seismic response parameters for the Peralta Wash bridge project design are based on the (AASHTO) LRFD Bridge Design Specifications [7], and represents horizontal peak ground acceleration (PGA) with 7 percent probability of exceedance in 75 years (approximately 1000-year return period). The 1000-year return period uniform hazard spectrum for the Peralta Wash bridge site, located at 35.601500º N latitude and -106.355800º W longitudinal, was obtained in accordance with the AASHTO ground motion maps for the probabilistic horizontal acceleration values corresponding to specific peak ground acceleration (PGA) and the spectral coefficients, namely the short- and long- period ground acceleration (Ss and S1 respectively) and corrected for the soil profile at the bridge site.

Ground motions caused by earthquakes are influenced not only by the distance from the fault planes, but also by the geology and soils found at the site. Subsurface profiles with soil layers overlaying bedrock that significantly differ in stiffness and density, will have amplified ground motions and a resonant period governed by the layer thickness and shear wave velocity of the materials. The damage potential of strong ground motions with respect to a structure is typically affected by the period of the strong earthquake motion and the resonant period of both the soil and the structure. Based on the subsurface profile at the bridge site, the average time-weighted shear wave velocity for the top 100 feet (VS100) of subsurface materials was estimated between 600 and 1,200 feet per second. Therefore, the site is classified as Class D according to the site class definitions specified in Table 3.10.3.1-1 of AASHTO.

A seismic hazard analysis to establish ground motions for seismic design was conducted. The recommended spectral acceleration coefficient values for probabilistic design with a return period of 1000 years were calculated using the program provided with the AASHTO LRFD Bridge Design Manual developed by the USGS (2008) entitled “Seismic Design Parameters”, version 2.10 [8] and are summarized in Table 2, Summary of Seismic Parameters Corrected for Site Class D.

TABLE 2: - Summary of Seismic Parameters Corrected for Site Class D

Horizontal Peak Ground Acceleration, (As) 0.195g

Horizontal Response Spectral Acceleration at Period of 0.2 sec, (SDs) 0.465g

Horizontal Response Spectral Acceleration at Period of 1.0 sec, (SD1) 0.217g

Site Factor at Zero-Period of Acceleration Spectrum, (Fpga) 1.55

Site Factor at Short-Period Range of Acceleration Spectrum, (Fa) 1.56

Site Factor at Long-Period Range of Acceleration Spectrum, (Fv) 2.40

The 5 percent damped design response spectrum for Site Class D is shown in Illustration 1, Design Response Spectrum Corrected for Site Class D, and the supporting data is presented in Table 3, Summary of Design Response Spectrum Data for Site Class D.

Peralta Wash Bridge NM IRR 85 (1) 8 February 2015

Illustration 1 - Design Response Spectrum Corrected for Site Class D

TABLE 3: - Summary of Design Response Spectrum Data for Site Class D

Period, T(sec)

Spectral Acceleration, Sa (g)

Displacement, Sd (in.)

0.00 0.193 0.000 (PGA)(Fpga) = As

0.09 0.465 0.042

0.20 0.465 0.182 (Ss)(Fa) = SDs

0.47 0.465 0.992 (Ss)(Fa) = SDs

0.50 0.435 0.500

0.60 0.362 0.600

0.80 0.272 0.800

1.00 0.217 2.123 (S1)(Fv) = SD1

1.20 0.181 1.200

1.40 0.155 1.400

1.60 0.136 1.600

1.80 0.121 1.800

2.00 0.109 2.000

2.20 0.099 2.200

2.40 0.091 2.400

2.60 0.084 2.600

2.80 0.078 2.800

3.00 0.072 3.000

Based on the long acceleration coefficient SD1 value of 0.217g calculated as Fv. S1, the bridge site is assigned to seismic hazard Zone 2 according to Table 3.10.6-1 in AASHTO. Seismic hazard zones reflect the variation in seismic risk in different regions needing different requirements for design as depicted in Table 4.7.4.3.1-1 in AASHTO.

0.05

0.1 0.15

0.2 0.25

0.3 0.35

0.4 0.45

0.5

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00

Sp ec tr al

A cc el er at io n, S a (g

Period, T (sec)

Peralta Wash Bridge NM IRR 85 (1) 9 February 2015

SECTION THREE--SUBSURFACE INVESTIGATION

3.1 FIELD EXPLORATION AND LABORATORY TESTING PROGRAM

CFL geotechnical personnel conducted a subsurface investigation during September 8 through 15, 2014, to characterize the soils at each foundation location. The subsurface exploration program consisted of drilling a total of 4 borings labeled B-1 through B-4. Approximate boring locations are shown on Figure 3, Boring Logs. Subsurface conditions were logged and representative samples were transported to the CFLHD Materials Laboratory in Lakewood, CO, for testing. More detailed descriptions of the work performed for the subsurface investigation and laboratory test data are contained in Appendices A and B, respectively. Subsurface exploration and site photos are contained in Appendix D.

Select soil samples were tested for design of the structure foundation. Most of the soil samples were combined from samples showing similar material parameters for more adequate testing size.

The laboratory testing program included physical parameters and electrochemical tests in accordance with following procedures:

• Grain Size Analysis of Granular Soils, AASHTO T 311 and ASTM D 1140,

• Atterberg Limits, AASHTO T 89 and 90,

• Soil Classification, ASTM D 2487 and AASHTO M 145, and

• Soil Resistivity and pH, AASHTO T 288 and 289, respectively.

Laboratory test results are summarized in Appendix B, Table B-1.

Peralta Wash Bridge NM IRR 85 (1) 10 February 2015

SECTION FOUR--ANALYSIS AND RECOMMENDATIONS

For the analysis and foundation design of the proposed bridge, geotechnical profiles were developed from subsurface conditions encountered during the geotechnical investigation. The recommendations and construction considerations are discussed in the following sections. All foundations are in accordance with the American Association of State Highway and Transportation Officials (AASHTO) probabilistic Load and Resistance Factor Design (LRFD), 5th edition, 2010 [7].

4.1 GEOTECHNICAL PROFILE

A total of four borings labeled B-1 through B-4 were completed near the proposed bridge abutment and pier locations, as shown in Table 4, Summary of Borings. All borings at the proposed bridge site were advanced to appropriate depths for deep foundations using PQ size casing. Encountered materials were tested with a split spoon sampler in conjunction with the Standard Penetration Test (SPT) [9], logged, and sampled in the field, and were sent to the laboratory for further testing to estimate materials physical parameters for design.

TABLE 4:- Summary of Borings Boring

No.

Foundation

Type Boring

Depth, ft Station, ft Offset from

Centerline, ft Ground

Elevation, ft B-1 Abutment 1 101 09+92.12 6.00 Rt 5275.75

B-2 Pier 1 80.5 10+84.28 0.71 Lt 5259.8 B-3 Pier 2 77.0 11+56.68 4.28 Lt 5259.6 B-4 Abutment 2 80.0 12+42.12 6.00 Rt 5276.49

The SPT N-values within the overburden materials range from N=6 near the surface to refusal (>50 blows/6 inch) and generally increased with depth. Bedrock was not encountered in any of the borings. The refusal values were not considered in estimating the material parameters for design due to the existence of gravel and large rock fragments. The SPT-N values were corrected for hammer efficiency and overburden pressure to obtain the N1(60) values for LRFD foundation design. Pore-water pressure was included in calculating the effective overburden stress below the groundwater table depth as observed in each boring. A summary of the steps used for determining a representative N1(60) value for foundation design purposes are shown in Table 5, N1(60) Calculation for Overburden Material.

Peralta Wash Bridge NM IRR 85 (1) 11 February 2015

TABLE 5:- N1(60) Calculation for Overburden Material

Boring SPT Depth1, ft σv' 2, lbf/ft2 N3 N60

CN

5 N1(60)

B-1

1 6 720 15 20.0 1.343 26 2 11 1320 19 25.3 1.141 28 3 16 1915 8 10.7 1.016 10 4 21 2495 6 8.0 0.928 7 5 26 3095 19 25.3 0.856 21 6 31 3695 16 21.3 0.797 16 7 36 4295 8 10.7 0.746 7 8 41 4895 15 20.0 0.702 14 9 46 5495 12 16.0 0.664 10

10 51 6095 9 12.0 0.629 7 11 56 6700 22 29.3 0.598 17 12 61 7325 24 32.0 0.568 18 13 66 7763 40 53.3 0.548 29 14 71 8076 60 80.0 0.535 42 15 76 8411 90 120.0 0.521 62 16 81 8749 81 108.0 0.508 54 18 91 9425 84 112.0 0.483 54 19 96 9763 39 52.0 0.472 24 20 101 10101 77 102.7 0.460 47

B-2

1 6.5 780 15 20.0 1.317 26 2 11.5 1380 24 32.0 1.126 36 3 16.5 1955 10 13.3 1.009 13 4 21.5 2530 12 16.0 0.923 14 5 26.5 3130 17 22.7 0.852 19 6 31.5 3730 17 22.7 0.793 18 7 36.5 4330 10 13.3 0.743 9 8 41.5 4774 19 25.3 0.711 18 9 46.5 5112 43 57.3 0.688 39

10 51.5 5450 51 68.0 0.667 45 11 56.5 5788 - - - - 12 61.5 6126 74 98.7 0.627 61 13 66 6300 86 114.7 0.618 70 14 71.5 6672 - - - - 15 75.3 6929 - - - - 16 80.5 7280 - - - -

B-3

1 26 3120 11 14.7 0.853 12 2 45 5400 14 18.7 0.670 12 3 55 6038 24 32.0 0.632 20 5 66 6782 98 130.7 0.593 77 6 77 7526 69 92.0 0.559 51

B-4

1 6.5 780 15 20.0 1.317 26 2 11.5 1380 19 25.3 1.126 28 3 16.5 1980 8 10.7 1.005 10 4 21.5 2555 6 8.0 0.920 7 5 26.5 3155 19 25.3 0.849 21 6 31.5 3755 16 21.3 0.791 16 7 36.5 4355 8 10.7 0.742 7 8 41.5 4955 15 20.0 0.698 14 9 46.5 5555 12 16.0 0.660 10

10 51.5 6155 9 12.0 0.626 7 11 56.5 6780 22 29.3 0.594 17 12 61.5 7405 24 32.0 0.564 18 13 66.5 8030 40 53.3 0.537 28 14 71.5 8430.4 60 80.0 0.521 41 15 76.5 8768.4 90 120.0 0.508 60 16 80 9005 77 102.7 0.499 51 17 6.5 780 15 20.0 1.317 26

1Begining depth of SPT-N reading 2Effective overburden pressure 3Field SPT-N value 4Calculated using AASHTO equation 10.4.6.2.4-2

5Calculated using AASHTO equation 10.4.6.2.4-1 6Calculated using AASHTO equation 10.4.6.2.4-3 7Refusal values neglected due to rock fragments

Peralta Wash Bridge NM IRR 85 (1) 12 February 2015

For use in design, subsurface materials were divided into 3 to 4 layers and assigned conservative material parameters at the top and bottom of each layer for each foundation location. Detailed descriptions of the bridge borings and boring logs are included in Appendix A. Material parameters were estimated for foundation design based on the field investigation results, laboratory test results, and presumptive empirical strength characteristics of similar materials. Selected design values are presented in Tables 6 and 7, Estimated Subsurface Material Parameters for Bridge Abutments and Piers, respectively.

TABLE 6:- Estimated Subsurface Material Parameters for Design of Bridge Abutments

Design Material

Bottom Depth, ft Layer Unit Weight γ (pcf) Cohesion c (psf)

Friction Angle θ (deg)

Rate of Increase of

Soil Modulus with Depth1 nh (ksi/ft) ABUTMENT 1 (0 depth = Top of Shaft Elevation 5269.0, WT Depth=56.2 ft)

Sand 8.25 1 Top

120 0 34 1.11 Bottom

Sand 43.2 2 Top 115 0 28 0.556 Bottom 120 30

Sand 64.8 3 Top 120 0 30 0.556 Bottom

Gravel 94.2 4 Top 125

0 40 1.39 Bottom 130

ABUTMENT 2 (0 depth = Top of Shaft Elevation 5270.0, WT Depth=61.0 ft)

Sand 10.0 1 Top

120 0 34 1.11 Bottom

Sand 33.5 2 Top 115 0 28 0.556 Bottom 120 30

Sand 60.0 3 Top 120 0 30 0.556 Bottom

Gravel 73.5 4 Top 130 0 40 1.39 Bottom 1 Table C10.4.6.3-2—Rate of Increase of Soil Modulus with Depth nh (ksi/ft) for Sand [7]

Peralta Wash Bridge NM IRR 85 (1) 13 February 2015

TABLE 7:- Estimated Subsurface Material Parameters for Design of Bridge Piers

Design Material

Bottom Depth, ft Layer Unit Weight γ (pcf) Cohesion c (psf)

Friction Angle θ (deg)

Rate of Increase of

Soil Modulus with Depth1 nh (ksi/ft) PIER 1 (0 depth = Top of Shaft Elevation 5259.0, WT Depth=38.2 ft)

Sand 10.7 1 Top

120 0 34 1.11 Bottom

Sand 34.2 2 Top 115 0 28 0.556 Bottom 120 30

Sand 60.5 3 Top 120 0 30 0.556 Bottom

Gravel 79.2 4 Top

130 0 40 1.39 Bottom

PIER 2 (0 depth = Top of Shaft Elevation 5259.0, WT Depth=45.4 ft)

Sand 24.4 1 Top

120 0 30 1.11 Bottom

Sand 54.4 2 Top 120 0 30 0.556

Bottom

Gravel 76.4 3 Top 130 0 40 1.39 Bottom 1 Table C10.4.6.3-2—Rate of Increase of Soil Modulus with Depth nh (ksi/ft) for Sand [7]

Boulders up to 2.5 feet in diameter were observed on the surface near the bridge location and adjacent slopes. Although boulders of this size were not observed in the borings, they are likely to be present throughout the overburden material. Bridge foundations are anticipated to be founded in the dense sandy, gravelly soils.

4.2 GROUNDWATER AND SOIL MOISTURE CONDITIONS

Groundwater elevations are generally required for evaluating side and tip resistance under axial loads, for computing lateral loads under lateral loading, for assessment of soil liquefaction under seismic loading, and for determining sound drilled shaft construction procedures in cohesionless soils.

Groundwater was detected in all borings at the time of the investigation as shown in Table 8, Groundwater Levels. Groundwater elevations may fluctuate between seasons and after precipitation events, due to the granular nature of the on-site soils. Groundwater and groundwater seepage should be anticipated during foundation construction.

Peralta Wash Bridge NM IRR 85 (1) 14 February 2015

TABLE 8: - Groundwater Levels Exploration Designation

Approximate Station

Top of Boring Elevation

(ft)

Date Read

Groundwater Depth

(ft)

Groundwater Elevation

(ft) B-1 09+92 5275.8 9/7/2014 63.0 5212.8 B-2 10+84 5259.8 9/9/2014 39.0 5220.8 B-3 11+57 5259.6 9/11/2014 46.0 5213.6 B-4 12+42 5276.5 9/15/2014 67.5 5209.0

*Groundwater depth and elevation as encountered during drilling phase of investigation.

4.3 BRIDGE FOUNDATION DESIGN

The factored bridge foundation loads at the strength limit state, provided by the CFL bridge engineer, are 1100-kips and 2100-kips for each abutment and pier, respectively. Spread footings were not considered for design because the scour depth to accommodate anticipated flood flows would require significant excavations and temporary shoring. Driven piles were projected to not be cost effective because the sour depth would control the pile design and require a pile cap. Due to the competent bearing materials, environmental, and aesthetic consideration, drilled shafts are recommended for the foundation of the proposed Peralta Wash Bridge. This type of foundation can best accommodate this large loss of support material while still providing structural rigidity.

4.3.1 Drilled Shaft Foundation Design

Drilled shafts are the recommended foundation system for the proposed bridge. Since bedrock was not encountered in the borings, the drilled shafts will gain their axial resistance from side and tip resistance in soil material below the scour depth. Scour elevations, provided by the CFL hydraulics engineer, are 5243.5 ft. for the abutments and 5235.8 ft. for the piers.

Axial loading conditions at the abutments were analyzed using the computer program SHAFT to determine the nominal skin friction (RS) versus depth and nominal end-bearing resistance (RB). Analyzed shaft diameters were 3.0-foot for the abutments and 3.5-foot for the piers. For the analysis, the zero depth was assumed to be the top of the shaft. Top of shaft elevations used are 5269.0 ft. at Abutment 1, 5259.0 ft. at the piers, and 5270.0 ft. at Abutment 2. The computation of the geotechnical resistances is based on the estimated soil parameters in Table 6 and 7. Conservative soil parameters were used in the analysis to allow for some material loosening during shaft construction which could result in reduction of shaft resistance and increase in shaft displacement. Groundwater was assumed to be at the elevations encountered at the time of drilling for each respective foundation, as shown in Table 8.

The program SHAFT assumes a minimum shaft penetration of 10 diameters below scour depth for the full tip resistance to develop. For penetrations less than 10 diameters, the end-bearing resistance is varied linearly from zero at the scour depth to a value computed at the 10-diameter depth. Additionally, tip resistance (end bearing) was neglected for materials with an estimated friction angle less than, or equal to 30 degrees. The limiting value of load transfer to end bearing is 80 kips/ft2 at a settlement of 5% of the base diameter.

Peralta Wash Bridge NM IRR 85 (1) 15 February 2015

The nominal (unfactored) end-bearing and side-friction resistances versus depth for the strength and extreme state limits at each abutment and pier are presented in Figures C1 through C4 in Appendix C. The output data from the SHAFT analysis is also contained in Appendix C.

The tip and side nominal resistance values can be used to calculate the total axial shaft resistance (RR) in accordance with Equation 10.8.3.5-1 (RR = φqp Rp + φqs Rs), as specified by AASHTO. Geotechnical resistance factors for all limit states specified by AASHTO, Table 10.5.5.2.4-1 are provided in Table 9, Resistance Factors for Drilled Shaft Design.

TABLE 9: - Resistance Factors for Drilled Shaft Design

Limit State Resistance Factor, φ

Side Resistance φqs Tip Resistance φqp

Strength 0.55 0.50

Service 1.00 1.00

Extreme Event 1.00 1.00

4.3.1.1. SETTLEMENT

Drilled shaft foundations should be designed at the service limit state not to exceed the 1.00-inch tolerable movement criteria provided by the structural engineer for the proposed bridge. Resistance factor of 1.0 for the service limit state is recommended to assess the ability of the foundation to meet the specified deflection criteria.

The normalized load-settlement curved provided in Figures 10.8.2.2.2-3 and 10.8.2.2.2- 4 of the AASHTO Bridge Design Specifications [7] were used to limit the nominal shaft base and side resistance computed as specified for the strength limit state for service limit state tolerable movement. The nominal (unfactored) bearing resistance at 1.00-inch of settlement at the service limit state (assumed mobilized end bearing and mobilized side friction) is provided as a function of depth (below scour) and shaft diameter on the same plots (Appendix C) as the strength and extreme event limit states. These values are based on short-term settlement for cohesionless soils. The trend-line in Figures 10.8.2.2.2-3 and 10.8.2.2.2-4 was used to determine the load transfer as shown in Table 10, for the drilled shaft design.

Peralta Wash Bridge NM IRR 85 (1) 16 February 2015

TABLE 10: - Normalized Load Transfer Values for Drilled Shaft Design

Drilled Shaft Diameter

(ft)

Ratio of Side Load Transfer to Ultimate Side Load Transfer

(Figure 10.8.2.2.2-3)

Ratio of End Bearing to Ultimate End Bearing

(Figure 10.8.2.2.2-4)

3.0 @ Abutments 0.80 0.70

3.5 @ Piers 0.80 0.60

Although elastic settlements vary with shaft length, it is assumed that relatively short-shaft lengths will be required and, therefore, shaft elastic shortening is negligible.

Differential settlements and long-term shaft group settlement are not anticipated in cohesionless soils but should be evaluated using the equivalent footing method after the drilled shaft groups are designed.

4.3.1.2. GROUP EFFECTS ON AXIAL RESISTANCE

The efficiency of groups of drilled shafts in cohesionless soils are not of concern as long as the center-to-center spacing between drilled shafts is greater than four times the shaft diameter. That is, the capacity of a shaft group is the sum of the resistance of all individual shafts in the group. If the center-to-center spacing of the drilled shafts is less than four times the diameter, the interaction effect between adjacent shafts shall be evaluated in accordance with section 10.8.3.6.3 of the AASHTO LRFD Bridge Design Specifications. This provision states that regardless of cap contact with the ground, the individual nominal resistance of each shaft should be reduced by a factor η as described below:

• η = 0.65 for a center-to-center spacing of 2.5 diameters,

• η = 1.0 for a center-to-center spacing of 4.0 diameters or more, and

• For intermediate spacing, the value of η may be determined by linear interpolation.

Besides the effect of overlapping zones of influence, effects of construction on ground conditions in and around the group can be significant. Excavated deep foundation elements in cohesionless soils tend to decrease the effective stress of the surrounding soils. Poorly controlled shaft construction methods can result in soil loosening during drilling and adversely reduce the lateral stress around other shafts within the group.

4.3.1.3. LATERAL LOADS

Lateral soil-structure interaction analysis and bending of the drilled shafts is performed by CFL bridge engineers on single and group shafts. For lateral loading analyses, use the subsurface soil parameters provided in Tables 6 and 7, Estimated Subsurface Material Parameters for Design of Bridge Abutments and Piers, respectively, to estimate the lateral load displacement behavior.

Peralta Wash Bridge NM IRR 85 (1) 17 February 2015

4.3.1.4. LIQUEFACTION AND LATERAL SPREAD

Soil liquefaction is a phenomenon in which a cohesionless soil deposit below the groundwater table loses a substantial amount of strength due to pore pressure generation resulting from earthquake strong ground shaking. The reason for the generation of pore pressure is that cohesionless soils tend to compact during earthquake cyclical shaking and this tendency causes the pore water pressures in the solid to increase until the pore water dissipates from the soil skeleton. This pore pressure increase, in turn, causes a reduction in effective stress and associated reductions in soil strength and stiffness.

Recently deposited and relatively loose natural soils and un-compacted or poorly compacted fill soils are susceptible to liquefaction. Submerged loose sand and silty sands are particularly susceptible to liquefaction. Loose silts and gravels may also have a potential for liquefaction. Dense natural, well-compacted fills, and cohesive soils are known to have a relatively low susceptibility to liquefaction. In addition, liquefaction studies have shown a reduced possibility of liquefaction in layers exist at greater than 50 feet in depth primarily due to increased density and layer confinement at depth.

Initial screening of site conditions for the potential for liquefaction was conducted in accordance with AASHTO Article 10.5.4.2. to determine if a more detailed evaluation of liquefaction would be necessary. The site is considered Seismic Zone 2 and subsurface materials are of sufficient density that the liquefaction potential at this site is considered low and no further analysis for liquefaction was performed.

4.3.1.5. FIELD TESTING

Steel crosshole sonic logging tubes (1.5-inch diameter steel tubes) should be installed in all drilled shafts prior to concrete placement for integrity testing. Crosshole sonic logging tubes cannot be installed in shafts less than 2 feet in diameter; therefore, a minimum shaft diameter of 2.5 feet is recommended. The recommended number of access tubes and tube spacing are dependent on the selected shaft diameter; refer to Table 11, Recommended Number of Access Tubes vs. Shaft Diameter. The crosshole sonic logging tests should be conducted in accordance with ASTM D-6760 for quality assurance/quality control of the drilled shafts.

TABLE 11:- Recommended Number of Access Tubes vs. Shaft Diameter Shaft Diameter (D), ft Number of Tubes Tube Spacing, degrees

2.5 ft < D < 3.0 ft 3 120

3.5 ft < D < 5.0 ft 4 90

4.3.2 Abutment Design

Abutments and wing walls should be designed to resist lateral earth pressures and other applicable lateral loads in accordance with AASHTO. Lateral earth pressure is influenced by the strength of the abutment backfill, the presence or absence of water, and the ability of the abutment or wall to move in response to lateral loads. Other loads, such as live loads, construction loads, and soil compaction loads should also be considered in the design.

Peralta Wash Bridge NM IRR 85 (1) 18 February 2015

Unbalanced water behind an abutment or wall adds significant lateral pressure and should be avoided by using free draining gravity outlets for water. Abutment and wing wall backfill should consist of select granular backfill.

The coefficient of at-rest earth pressure should be used for design if the abutment is so restrained that it cannot be expected to rotate (deflect at the top) 0.002 times the wall height.

Where deflection of the abutment can be expected, a coefficient of active earth pressure should be used for wall design. Active and at-rest lateral earth pressures of native materials, properly placed and compacted select granular backfill, and unclassified borrow above the water table are presented in Table 12, Lateral Earth Pressures for Bridge Abutments. The values are unfactored loads and assume that the surface of the soil slope behind the wall is horizontal.

Table 12:- Lateral Earth Pressures for Bridge Abutments

Backfill Type Assumed Backfill

Parameters Case

Unfactored Equivalent

Fluid Density (pcf)

Select Granular Backfill c = 0 psf Փ = 34 deg.

γ = 125 pcf

Active 35

At-Rest 55

Unclassified Borrow c = 0 psf Փ = 30 deg.

γ = 125 pcf

Active 42

At-Rest 63

Native Silty Sand (SM) c = 0 psf Փ = 30 deg γ = 125 pcf

Active 42

At-Rest 63

4.4 EMBANKMENTS

Proposed bridge design requires minimal embankment work. It is recommended that permanent embankments be constructed at 1V:2H slopes or flatter to maintain slope stability and facilitate vegetation growth. Settlements of embankments are considered negligible due to the low height, granular nature of on-site materials, and relatively deep groundwater table. Standard erosion control protection measures should be implemented.

4.5 TEMPORARY CUT SLOPES

Temporary cut slopes are anticipated for construction of the bridge foundations, drainage improvements, and to maintain traffic during construction. Design and safety of this work is the responsibility of the contractor. The work shall be performed in a manner to minimize hazards and exposure to the public, construction personnel, and equipment.

Peralta Wash Bridge NM IRR 85 (1) 19 February 2015

4.6 CORROSION POTENTIAL

An analytical test was conducted on selected samples collected from the site to determine if soils may have detrimental effects on concrete and buried metals. A combined soil sample from all four borings at various depths was tested for resistivity and pH chemical characteristics. The resistivity result (AASHTO T 288) is 5240 ohm x cm and the pH result is 6.4. The resistivity and pH results do not indicate an aggressive soil environment; therefore, sulfates and chlorides were not tested.

Standard corrosion protection measures should be implemented; however, sulfate resistant cement is not required.

4.7 CONSTRUCTION CONSIDERATIONS

Due the granular, and sometime loose, nature of materials encountered, temporary casing for drilled shaft construction is recommended. Where drilled shaft excavations extend below the groundwater, the use of a combination of temporary casing and slurry is anticipated to maintain the integrity of the shaft excavation. Heave and flowing sand conditions may develop if improper construction techniques are used. Only contractors with experience in similar ground conditions and work scope should be selected for drilled shaft construction.

Excavations are anticipated to encounter large boulders up to 2.5-foot size in diameter or larger, and plans for removal of theses obstructions should be included in the contractors shaft drilling procedures.

4.8 LIMITATIONS

The recommendations in this report are based on the data obtained from exploratory borings, field review, and laboratory test results. The results of these explorations and tests represent conditions at the specific locations indicated. Subsurface variations across the site are likely and may not become evident until excavation is performed. The Analysis and Recommendations sections in this report include interpretations and recommendations developed by the Government in the process of preparing the design. These interpretations are not intended as a substitute for the personal investigation, independent interpretation, and judgment of the Contractor.

Peralta Wash Bridge NM IRR 85 (1) 20 February 2015

SECTION FIVE--REFERENCES

[1] “Las Conchas Fire Response, Peralta Creek Flood Mitigation Measures”, Technical

Assistance Report for Pueblo de Cochiti, US Army Corps of Engineers, South Pacific Division, Albuquerque District, September 2012.

[2] U.S. Department of Transportation Federal Highway Administration, Plans for Proposed NM 85(1) Peralta Wash. Preliminary 30% Plans Dated 10/3/2014.

[3] U.S. Department of Transportation Federal Highway Administration, 30% Design

Technical Memorandum, NM IRR 85(1) Peralta Wash. Dated 10/9/2014.

[4] “The Cerrillos Uplift, the La Bajada Constriction, and Hydrogeologic Framework of the

Sant Doming Basin, Rio Grande Rift, New Mexico”, United States Geological Survey (USGS), Virginia, 2006, website: http://pubs.usgs.gov/pp/1720

[5] http://geohazards.usgs.gov/cfusion/qfault/query_main_AB.cfm

[6] http://geohazards.usgs.gov/cfusion/hazfaults_2014_search/query_main.cfm

[7] American Association of State Highway and Transportation Officials (AASHTO), 2010, LFRD BRIDGE DESIGN SPECIFICATIONS, 5th Edition.

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

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

[9] Rogers, J. David. Environmental & Engineering Geoscience, Vol. XII, No. 2, May 2006, pp.161-179. “Subsurface Exploration Using the Standard Penetration Test and the Cone Penetrometer Test.”

[10] SHAFT V.7.4 , ENSOFT, 2012.

[11] FHWA, 2010, Drilled Shafts: Construction Procedures and LRFD Design Methods, Publication FHWA-NHI-10-016, dated April.

http://pubs.usgs.gov/pp/1720 http://geohazards.usgs.gov/cfusion/qfault/query_main_AB.cfm http://geohazards.usgs.gov/cfusion/hazfaults_2014_search/query_main.cfm http://earthquake.usgs.gov/research/hazmap

FIGURES

NM 85(1)

Figure 1 – Regional Location Map, Cochiti, Pueblo, Albuquerque

Source: http://ngmdb.usgs.gov/maps/mapview

Figure 2 – Local Area Map, Peralta Wash Bridge

Sources: http://maps.google.com and ngmdb.usgs.gov/maps/mapview

Figure 3 – Engineering Geology / Boring Logs

Figure 4 – Geologic Map of the Cochiti Pueblo Area, New Mexico

Source: http://pubs.usgs.gov/pp/1720/downloads/pdf/p1720‐pl2.pdf

DETAIL A

Figure 4 / DETAIL A

List of Map Units ‐ Source: http://ngmdb.usgs.gov/maps/mapview

Qal – Alluvium deposited by Rio Grande tributaries (upper Pleistocene? And Holocene). Poorly sorted gravelly sand and sandy gravel deposited in channels and minor floodplain areas of tributary streams and as a broad alluvial apron along the west side of the Rio Grande valley (east edge of the Santo Domingo Pueblo SW quadrangle).

Diagonal hatchures – Areas of deep excavation and removal of sufficient volume of material so as to prohibit accurate mapping on this topographic base.

Qe – Eolian sand and silt (upper Pleistocene and Holocene). Massive fine sand and coarse silt forming 1‐5 m thick deposits in the western part of Santo Domingo Pueblo SW quadrangle.

Qtp4 – Terrace gravel (upper Pleistocene). Fill‐terrace gravel, 3‐8 m thick, with an upper surface approximately 18‐20 m above grade.

It is less than 3 m thick in lower Peralta Canyon, but reaches typical thickness near the mouth of the Santa Fe River.

Qf – Deposits of modern channel and floodplain of the Rio Grande (Holocene). Sand, mud and minor gravel, mostly within 3 m elevation of the present channel.

QTc – Cochiti Formation (lower Pleistocene and upper Miocene). Volcaniclastic sand and gravel in poorly sorted, tabular beds.

Qoa – Older alluvial deposits of the Rio Grande (Holocene and upper Pleistocene). Alluvial sand, gravel and silt, 10‐30 m thick, underlying a low‐relief surface about 3 m above the active channel of the Rio Grande.

QTsl and QTslg – Sand deposited by axial river (ancestral Rio Grande). Mapped as QTsl in the Santo Domingo Pueblo SW quadrangle, but differentiated from QTslp as QTslg where unit thickness and map scale permitted in the quadrangle. Contains about 35‐40% quartzite, 20% granitic and metamorphic rocks and the remainder mostly volcanic rocks. Interbedded with Cochiti Formation (QTc) and the Peralta Tuff Member of the Bearhead Rhyolite (Tbp, not shown on above map).

APPENDIX A

FIELD EXPLORATION PROGRAM

APPENDIX A

FIELD EXPLORATION PROGRAM

A.1 INTRODUCTION

The Central Federal Lands Highway Division (CFLHD) Geotechnical Section completed a field exploration program for Peralta Wash Bridge, PR 85 (1) Project, during September 2014. The scope of work for the field exploration program included drilling a total of four borings. The field exploration program was coordinated and observed by an Engineering Geologist from CFLHD. Field exploration location plans, as well as individual borings are attached. These logs represent a compilation of field and laboratory data and description of the soil samples by CFLHD Geotechnical personnel. The methods used to conduct the field exploration program are described below. Photos of the boring locations are included in the attachments. Representative soil and rock samples collected during the field exploration program were transported to the CFLHD Materials Laboratory in Lakewood, Colorado for testing. A summary of the laboratory testing program is provided in Appendix B.

A.2 EXPLORATION

Borings Geomechanics Southwest Inc., of Tucson, Arizona provided the drilling services for the soil borings. Borings were completed using a CME 75 truck-mounted drill rig.

Borings were drilled between September 8 and 15, 2014. A total of four geotechnical borings, B-1 through -4, were completed to depths ranging from approximately 77 to 101 feet below ground surface in close proximity to abutment and pier locations for the structure foundation design. Borings were drilled using pneumatic percussion hammer system (ODEX) and mud rotary system. SPTs were taken with an automatic hammer system.

Water was encountered at the time of drilling, and field personnel measured water levels in the borings. Fluctuations in the ground water level due to seasonal and climatic effects are expected.

The location and elevation of individual borings were surveyed. Boring locations are listed on individual boring logs and are shown below in Table A1. Following drilling activities, field personnel backfilled the borings with bentonite chips and grout in accordance with applicable local, state, and federal regulations.

TABLE A1 - FIELD EXPLORATION LOCATIONS

Approx.

Station

Offset

(ft) Northing Easting Exploration

Type Exploration Designation

Approx.

Depth (ft)

Exploration Purpose

09+92.12 6.00 Rt 1608936.90 1674108.62 Bridge Foundation

B-1 101.0 Bridge Foundation 10+84.28 0.71 Lt 1608969.33 1674195.14 B-2 80.5

11+56.68 4.28 Lt 1608996.35 1674262.41 B-3 77.0 12+42.12 6.00 Rt 1609041.40 1674335.73 B-4 80.0

A.3 SOIL SAMPLING

Borings

Disturbed samples were obtained from the borings in accordance with the Standard Penetration Test (SPT), the procedures of which are detailed in AASHTO T-206. The SPT involves driving a 2-inch outside diameter, 1.375-inch inside diameter split spoon sampler a depth of 18 inches with a 140-pound hammer falling a distance of 30 inches. The number of blows required to advance the split-spoon sampler through each of the 6-inch increments was recorded. The SPT resistance, or N-value, is defined as the number of blows required to drive the sampler over the second and third 6-inch increments. The N-value provides a means for evaluating the relative density or compactness of cohesionless (granular) soils and consistency or stiffness of cohesive (fine-grained) soils. An energy corrected N-value, N60, is used to standardize the energy levels of the hammer system in the SPT to 60% efficiency. Recent energy measurements of the automatic hammer system employed for the SPT’s on this project indicate an efficiency of 80%.

Because high penetration resistance prevented driving the total length of the sampler at times, the…