Geotechnical Contract Design No. PS Memoranda 4350 2000

WESTSIDE SUBWAY EXTENSION PROJECTContract No. PS‐4350‐2000

Westside Subway Extension Project Contract C1045

Geotechnical Design Memoranda Amendment 4 – November 19, 2013 Amendment 3 – October 15, 2013 May 22, 2013

Geotechnical Design Memoranda

Table of Contents

W E S T S I D E S U B W A Y E X T E N S I O N P R O J E C T Page i Amendment 4 – November 19, 2013 Amendment 3 – October 15, 2013 May 22, 2013

List of Design Memoranda

The following Design memoranda are included in this file:

Wilshire/La Brea, Wilshire/Fairfax and Wilshire/La Cienega Stations

Tunnels ‐ Reaches 1 through 3

W E S T S I D E S U B W A Y E X T E N S I O N P R O J E C T

WILSHIRE/LA BREA, WILSHIRE/FAIRFAX, WILSHIRE/LA CIENEGA STATIONS

AMEC Environment & Infrastructure, Inc. 6001 Rickenbacker Road Los Angeles, Calfiornia 90040, USA Ph: +1 (323) 889‐5300 Fax +1 (323) 721‐6700 www.amec.com

MEMO

To Ms. Amanda Elioff, P.E. Parsons Brinckerhoff

Date Amendment 3 Amendment 4

May 22, 2013 October 15, 2013 November 19, 2013

Project No

4953‐11‐1423

Subject Geotechnical Design Memorandum – Section 1 (Amendment 4) Wilshire/La Brea, Wilshire/Fairfax and Wilshire/La Cienega Stations Westside Subway Extension, Los Angeles, California

This geotechnical design technical memorandum (GDMTM) containing geotechnical design data has been prepared for the three stations within Section 1 of the proposed Westside Subway Extension project for the Los Angeles County Metropolitan Transportation Authority (Metro), as part of the Advanced Preliminary Engineering (Adv. PE) phase study. This TM GDM pertains to Wilshire/La Brea, Wilshire/Fairfax and Wilshire/La Cienega Stations.

The results of the Advanced Conceptual Engineering (ACE), Preliminary Engineering (PE) and Adv. PE phase investigations performed for these stations were presented in their respective Geotechnical Data Reports (GDRs), dated May 2013. Additional explorations were performed in early 2013 at station entrance areas at the Wilshire/La Brea and Wilshire/Fairfax stations. The additional data was included in Amendment #2 of the GDRs dated September 16, 2013. The interpretation of the additional data is included in this Amendment #34 of the TMGDM.

This TM GDM presents geotechnical recommendations for foundation design, excavation support, station box design, dewatering and groundwater control, and for earthwork planned for the three stations. If there is any conflict between the data presented in this report and the GBR, data presented in the GBR will prevail.

The geotechnical parameters presented in this report reflect the design team’s judgment of anticipated subsurface conditions and ground behavior based on the construction means and methods anticipated. The design data presented herein were established by considering available geologic and geotechnical data, together with past construction experience and anticipated construction methods in similar ground conditions. Development of the project design recommendations required interpretation of the data obtained from various sources, including: geologic maps; hollow stem auger, rotary, and core borings; geophysical surveys; and in‐situ and laboratory tests, as well as the consideration of information from previous construction projects completed in similar geologic conditions. While actual conditions encountered in the field are expected to be within the range of conditions discussed herein, the locations where specific ground and groundwater conditions are encountered may vary from those described in this report. In addition to the specific conditions described herein, the ground behavior will also depend on the construction sequence and methods employed, as well as the Contractor’s equipment and workmanship. The project design, therefore, assumes that the construction methods

Geotechnical Design Memorandum – Section 1 Westside Subway Extension

Wilshire/La Brea, Wilshire/Fairfax and Wilshire/La Cienega Stations May 22, 2013

Amendment 3 October 15, 2013 Amendment 4 November 19, 2013

and level of workmanship will be consistent with those that can reasonably be expected from an experienced and qualified contractor.

It is our understanding that this TM GDM is being prepared for inclusion in the Request for Proposal Package being prepared for a Design‐Build Contract for Section 1.

It is a pleasure to be of continuing professional service to you. Please call if you have any questions or if we can be of further assistance.

Sincerely,

AMEC Environment & Infrastructure, Inc.

Hari Ponnaboyina, P.E. Senior Engineer‐Geotechnical

Martin B. Hudson, Ph.D., G.E. Project Manager/Principal Engineer

Perry A. Maljian, G.E. Senior Principal Engineer/ Senior Vice President

Geotechnical Design Memorandum – Section 1 Westside Subway Extension

Wilshire/La Brea, Wilshire/Fairfax and Wilshire/La Cienega Stations May 22, 2013

Amendment 3 October 15, 2013 Amendment 4 November 19, 2013

SUMMARY OF REVISIONS TO THE MAY 22, 2013AMENDMENT 3 TMGDM

Section/Figure/Table Revisions Page Nos.

Section 1 Changed “TM” to “GDM” 1

Section 1, Table 1‐1 Change depths to bottom of stations 1

Section 3.1 Added reference to latest Metro Seismic Design Criteria 9

Table 3‐3 Corrected free‐field displacement of Wilshire/Fairfax Station for ODE

13

Table 4‐2 Corrected pH range and design values 25‐27

Table 4‐3 Corrected pH range and design values 28‐29

Section 4.9.3 Deleted coefficient of friction between station walls and supporting soils

34

Section 6.0 Changed “TM” to “GDM” 37

Section 7.0 Added references of Amendment to the 2‐GDRs 39

Technical Memorandum for Stations – Section 1 Westside Subway Extension

May 22, 2013 Amendment 3 October 15, 2013

Amendment 4 November 19, 2013 Page i

Table of Contents

1.0 DESCRIPTION OF STATIONS ..................................................................................................... 1

2.0 ENGINEERING PROPERTIES OF PRINCIPAL GEOLOGIC UNITS .................................................... 1

3.0 DYNAMIC SITE CHARACTERISTICS ............................................................................................ 9

3.1 Response Spectra ................................................................................................................ 9

3.2 Time Histories and Spectral Matching ................................................................................ 9

3.3 Site Response Analysis and Free‐Field Differential Displacement .................................... 12 3.3.1 Lateral Spring Stiffness ........................................................................................ 13 3.3.2 Vertical Spring Stiffness ....................................................................................... 15

4.0 DESIGN AND CONSTRUCTION ................................................................................................ 15

4.1 Geotechnical Considerations ............................................................................................ 15

4.2 Groundwater Levels .......................................................................................................... 16 4.2.1 Wilshire/La Brea Station ...................................................................................... 16 4.2.2 Wilshire/Fairfax Station ....................................................................................... 16 4.2.3 Wilshire/La Cienega Station ................................................................................. 16 4.2.4 Design Groundwater Level for Three Stations ..................................................... 17

4.3 Seismic Design Considerations ......................................................................................... 17

4.4 Excavation Methods ......................................................................................................... 17

4.5 Dewatering and Groundwater Control ............................................................................. 17 4.5.1 Parameters Used for Design Estimates ............................................................... 17 4.5.2 Estimated Groundwater Inflows .......................................................................... 18

4.6 Ground Heave and Basal Stability ..................................................................................... 19

4.7 Excavation Support ........................................................................................................... 19 4.7.1 Geotechnical Design Parameters ......................................................................... 19 4.7.2 Lateral Earth Pressures ........................................................................................ 19 4.7.3 Hydrostatic Pressures .......................................................................................... 20 4.7.4 Surcharge Pressures ............................................................................................. 20 4.7.5 Seismic Earth Pressures ....................................................................................... 21 4.7.6 Design of Soldier Piles .......................................................................................... 21 4.7.7 Lagging ................................................................................................................. 22 4.7.8 Anchor Design ...................................................................................................... 22 4.7.9 Internal Bracing .................................................................................................... 31 4.7.10 Deflection ............................................................................................................. 31 4.7.11 Monitoring ........................................................................................................... 31

4.8 Gassy Condition Design Considerations ........................................................................... 32

4.9 Foundations ...................................................................................................................... 32 4.9.1 Bearing Value ....................................................................................................... 32

Technical Memorandum for Stations – Section 1 Westside Subway Extension May 22, 2013 October 15, 2013 Amendment 3 November 19, 2013 Amendment 4 Page ii

4.9.2 Settlement ........................................................................................................... 33 4.9.3 Lateral Resistance ................................................................................................ 33 4.9.4 Soil Springs ........................................................................................................... 33

4.10 Earthwork.......................................................................................................................... 33

4.11 Corrosion Potential ........................................................................................................... 34

5.0 PRIOR EXPERIENCE WITH SIMILAR PROJECTS ......................................................................... 34

6.0 LIMITATIONS AND BASIS FOR RECOMMENDATIONS .............................................................. 35

7.0 REFERENCES .......................................................................................................................... 36

List of Figures Figure 4‐1: Lateral Pressure Distribution .................................................................................................... 30

List of Tables Table 1‐1: Station Location and Dimensions for Design ............................................................................... 1

Table 2‐1: Engineering Properties of Principal Geologic Units (for Wilshire/La Brea Station) ..................... 3

Table 2‐2: Engineering Properties of Principal Geologic Units (for Wilshire/Fairfax Station) ...................... 5

Table 2‐3: Engineering Properties of Principal Geologic Units (for Wilshire/La Cienega Station) ................ 7

Table 3‐1: Acceleration Response Spectra for Stations and Ancillary Structures ....................................... 11

Table 3‐2: Seed Time Histories ................................................................................................................... 12

Table 3‐3: Free‐Field Displacement (ODE and MDE) .................................................................................. 13

Table 3‐4: Lateral Soil Spring Stiffness for Arch Module (Small Strain, ODE and MDE) ............................. 14

Table 3‐5: Vertical Spring Stiffness (Small Strain, ODE and MDE) .............................................................. 15

Table 4‐1: Geotechnical Design Parameters (Wilshire/La Brea Station) .................................................... 23

Table 4‐2: Geotechnical Design Parameters (Wilshire/Fairfax Station) ..................................................... 25

Table 4‐3: Geotechnical Design Parameters (Wilshire/La Cienega Station) ............................................... 28

Appendix Appendix A: Results of 1D and 2D Site Response Analyses and Dynamic Soil Spring Analyses – Wilshire/Fairfax

Station



Amendment 4 November 19, 2013 Page 1

1.0 DESCRIPTION OF STATIONS

The stations will be constructed in a cut and cover operation. An arch roof module was assumed for the station box. The majority of the station excavation support will be internally braced with struts. However, tieback systems may be selected by the contractor for portions of the station excavation, or station entrances and appendages. The following table presents information pertaining to the location of the stations and approximate dimensions of the stations that were used to develop the geotechnical recommendations presented in this TMGDM.

Table 1-1: Station Location and Dimensions for Design

Station Location Length (feet)

Width (feet)

Depth to Top of Arch Roof, bgs

(feet)

Depth to Top of Station Walls bgs

(feet)

Depth to Bottom of Station Box

bgs (feet)

Wilshire/La Brea1 50 ft E. of S. Orange Dr to 250 ft

W. of La Brea Ave. 985 60 20 30 75 to 80

Wilshire/Fairfax2 50 feet W. of S. Ogden Dr to

about 270 feet W. of S. Fairfax Ave.

840 60 15 to 20 25 to 30 6570 to 75

Wilshire/La Cienega3 S. Tower Dr to La Cienega Blvd. 985 60 25 30 65 to 70

1. Station entrance is planned northwest of the intersection of Wilshire Blvd., and La Brea Avenue 2. One station entrance is planned southeast of the intersection of Wilshire Blvd., and Orange Grove Avenue. A second station

entrance is planned at about 200 feet west of Intersection of Wilshire Blvd., and Fairfax Avenue 3. Station entrance is planned northeast of the intersection of Wilshire Blvd., and La Cienega Blvd

2.0 ENGINEERING PROPERTIES OF PRINCIPAL GEOLOGIC UNITS

The geologic units that will be encountered in the station excavations, from oldest to youngest, are the Pleistocene‐age San Pedro Formation, Pleistocene‐age older alluvium / Lakewood Formation, Holocene‐age alluvium, and modern artificial fill. The Pliocene‐age sedimentary rock of the Fernando Formation is not anticipated in station excavations, but will likely be encountered in soldier pile excavations at Wilshire/La Brea and possibly at Wilshire/Fairfax Stations.

Engineering properties were compiled in these principal geologic units and statistical analyses were performed to estimate the lower bound, upper bound and a design value for each property. The properties were evaluated by sub‐dividing each geologic unit into fine‐grained and coarse‐grained portions before performing the statistical analysis. The engineering and index properties for the earth materials at the stations are listed below:

SPT Blow Counts

Technical Memorandum for Stations – Section 1 Westside Subway Extension May 22, 2013 October 15, 2013 Amendment 3 November 19, 2013 Amendment 4 Page 2

Moisture Content

Bulk Density

Dry Density

Fines Content

Specific Gravity

Liquid Limit and Plasticity Index

Expansion/Collapse

Degree of Saturation

Void Ratio

Effective Cohesion and Friction Angle

Undrained Cohesion and Friction Angle

Elastic Parameters – Young’s Modulus and Poisson’s Ratio

Hydraulic Conductivity

Compression Index (Cc)

Recompression Index (Cr)

At‐rest Lateral Earth Pressure Coefficient (K0)

Unconfined Compression Strength (UCS)

Soil Abrasion

Corrosion (Minimum Resistivity, pH, Chloride Content, Sulfate Content)

The estimated range (lower bound and upper bound) and a design value of the engineering properties listed above for Wilshire/La Brea, Wilshire/Fairfax and Wilshire/La Cienega Stations are presented in Table 2‐1, Table 2‐2 and Table 2‐3, respectively.



Amendment 4 November 19,2 013 Page 3

Table 2-1: Engineering Properties of Principal Geologic Units (for Wilshire/La Brea Station)

Geologic Formation Lakewood (Qlw) San Pedro (Qsp) Fernando (Tf)

Predominant Grain Size Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Fine-Grained USCS Soil Classification SM, SC, SP CL, CH, ML, CL-ML SP, SP-SM, SW, SW-SM, SM, SC CL, CH, ML, CL-ML Siltstone

Engineering Properties Range1 Design Value1 Range1 Design Value1 Range1 Design Value1 Range1 Design Value1 Range1 Design Value1

SPT Blowcounts 2 10 to 80 34 7 to 92 27 12 to 100 87 18 to 100 39 25 to 100 44 Moisture Content (%) 7.9 to 26.2 16.8 14.5 to 37.7 23.6 11.6 to 35.4 19.7 18.1 to 38.0 25.4 25.4 to 57.9 37.3 Dry Density (pcf) 100 to 120 108 84 to 109 100 89 to 112 104 85 to 105 98 61 to 97 84 Total Density (pcf) 121 to 137 128 114 to 133 124 116 to 132 125 117 to 129 122 96 to 122 114 Fines Content (%) 14 to 48 31 49 to 82 57 5 to 47 12 65 to 92 81 83 to 99 98 Specific Gravity 2.72 to 2.81 2.76 2.45 to 2.78 2.73 2.58 to 2.78 2.70 2.76 to 2.80 2.79 2.53 to 2.60 2.57 Liquid Limit (%) 27 to 45 37 29 to 79 47 NP to 45** 23** 32 to 74 52 39 to 59 45 Plasticity Index (%) 8 to 24 13 8 to 60 27 NP to 32** 16** 12 to 56 26 14 to 24 19 Expansion (%) NA NA 0.05 to 1.0** 1.0** NA NA 0.05 to 1.0* 1.0* 0.03 to 0.21** 0.21** Collapse (%) 0 to 0.12** 0.12** NA NA 0.01 to 0.07 0.03 NA NA 0.04 to 0.17** 0.12** Degree of Saturation (%) # 65 to 100 94 81 to 100 97 53 to 100 93 87 to 100 99 88 to 100 100 Void Ratio 0.38 to 0.65 0.54 0.52 to 0.97 0.67 0.51 to 0.87 0.59 0.57 to 0.95 0.72 0.67 to 1.59 0.90 Effective Friction Angle from Direct Shear Test 3 (degrees)

25 to 33 27 11 to 34 25 25 to 34 31 26 to 33** 29** 8 to 31 24

Effective Cohesion from Direct Shear Test 3 (psf)

0 to 800 500 250 to 3,400 725 0 to 1,200 200 0 to 900** 300** 0 to 4,000 1,300

Effective Friction Angle from Triaxial Test 4 (degrees)

Range = 29 to 41 (Design Value = 34) 31** (Design Value = 31**)

Effective Cohesion from Triaxial Test 4 (psf)

Range = 0 to 1,100 (Design Value = 250) 2,000** (Design Value = 2,000**)

Undrained Friction Angle from Triaxial Test 4 (degrees)

Range = 22 to 45 (Design Value = 31) 30 ** (Design Value= 30**)

Undrained Cohesion from Triaxial Test 4 (psf)

Range = 50 to 3,500 (Design Value = 700) 950** (Design Value= 950**)

Unconfined Compressive Strength (psi) NA Range = 30 to 94 (Design Value = 60) Young’s Modulus from SPT Correlation 5 (ksf)

222 to 1,047 417 68 to 460 241 189 to 1641 957 186 to 674 388 253 to 754 418

Young’s Modulus from Triaxial Test 6 (ksf)

2,178** 2,178* 1,220 to 1,638** 1,517** 3,542 to 4,929** 4,233** 1,200 to 1,890** 1,545** 2,540** 2,540**

Poisson’s Ratio Range = 0.31 to 0.4 (Design Value = 0.34) Hydraulic Conductivity (ft/day)7 10-2 to 50* 5* 10-7 to 10-1 * 10-5 * 10-2 to 500* 50* 10-7 to 10-1 * 10-5 * 10-7 to 10-3 * 0.5 x10-4 * Compression Index (Cc) 0.063 to 0.080** 0.071** 0.043 to 0.077** 0.06** 0.013 to 0.064 0.044 0.102 to 0.139** 0.121** 0.060 to 0.148 0.122 Recompression Index (Cr) 0.004 to 0.015** 0.010** 0.01 to 0.034** 0.034** 0.004 to 0.015 0.010 0.011 to 0.014** 0.012** 0.032 to 0.044 0.038 At-Rest Soil Pressure Coeff., Ko Range = 0.38 to 1.01** (Design Value = 0.5**) Unconfined Compression (psi) NA NA 10 to 100* 50* NA NA 10 to 100* 50* 30 to 94 60 Soil Abrasion Test 23 to 54* 34* 1 to 12* 3* 15 to 35 28 1 to 12* 3* 2 to 15** 4** Corrosivity Results: 8 Minimum Resistivity (ohm-cm) 390 to 1640** 390** 720 to 1440 720 1040 to 2160 1,040 1040 to 1520 1,040 244 to 384 244 pH 4.6 to 7.2** 4.6** 7.4 to 8.4 7.4 4.6 to 8.0 4.6 7.8 to 8.3 7.8 5.2 to 7.4 5.2


Table 2-1: Engineering Properties of Principal Geologic Units (for Wilshire/La Brea Station) (continued)

Geologic Formation Lakewood (Qlw) San Pedro (Qsp) Fernando (Tf)

Predominant Grain Size Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Fine-Grained USCS Soil Classification SM, SC, SP CL, CH, ML, CL-ML SP, SP-SM, SW, SW-SM, SM, SC CL, CH, ML, CL-ML Siltstone

Chloride Content (ppm or mg/kg) 15 to 69 ** 69** 8 to 22 22 9 to 251 251 2 to 17 17 285 to 888 888 Sulfate Content (ppm or mg/kg) 63 to 165** 165** 44 to 431 431 13 to 1585 1585 85 to 171 171 2426 to 6509 6,509

* No test data; reported values are based on data from adjacent stations and reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience ** Limited data; reported values are based on data at the station and that from adjacent station and reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience “NP” indicates non-plastic material # Estimated using assumed specific gravity of 2.65 when a specific gravity test was not performed “NA” indicates engineering property not applicable for the material type or no test data pcf = pounds per cubic foot; psf = pounds per square foot; psi = pounds per square inch; cm = centimeter; ppm = parts per million; mg = milligrams; kg = kilograms Notes: 1. Data presented here are based on ACE, PE and Adv. PE phase explorations as well as applicable prior explorations as discussed in Tunnel GDRs 2. Blow counts from environmental hollow-stem-auger borings were not considered 3. Effective cohesion and friction angle are based on yield values from slow direct shear tests. See figure in Appendix E of Wilshire/La Brea GDR on how yield values were picked. 4. Cohesion and friction angle are based on peak shear strength values from Triaxial consolidated-undrained tests. Effective values are based on effective stress and undrained values are based on total stress 5. Based on relationship between elastic modulus and SPT N1,60 from Sabatini et al., (2002, P.148) 6. Based on secant modulus computed at 0.1+0.05% axial strain from Triaxial consolidated-undrained tests 7. Hydraulic conductivity values were based on published data (Department of Water Resources Bulletin 118, California’s Groundwater Update, 2003) and site-specific pumping test data 8. For soil corrosivity, the design values correspond to minimum resistivity, lowest pH and highest values for chloride and sulfate content




Table 2-2: Engineering Properties of Principal Geologic Units (for Wilshire/Fairfax Station)

Geologic Formation Younger Alluvium (Qal)/Older Alluvium (Qalo) /Lakewood

Formation (Qlw)

Tar Impacted- Younger Alluvium (Qal)/Older Alluvium (Qalo) /Lakewood

Formation (Qlw) San Pedro Formation (Qsp)

Tar-Impacted San Pedro Formation (Qsp)

Tar-Impacted Fernando Formation (Tf)

Predominant Grain Size Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Fine-Grained

USCS Soil Classification SM, SC, SP-SM, SP, SW, GW ML, CL,CH, CL-ML SM, SC ML, CL SC CL,ML GM, SC, SM, SP-SM,SP,SW-

SM ML Siltstone

Engineering Properties Range1 Design Value1

Range1 Design Value1








SPT Blowcounts 2 8 to 79 23 7 to 59 14 16 to 50 23 16 to 36 19 49 to 94 72 9 to 31 17 8 to 100 67 15 to 100 46 21 to 68 44 Moisture Content (%) 10 to 22 17 12 to 35 21 3 to 37 16 13 to 21 19 9 to 10** 9** 12 to 22 16 2 to 32 6 4 to 42 15 7 to 32 20 Dry Density (pcf) 105 to 111 109 87 to 121 104 82 to 126 109 89 to 95** 92** 112 to 118** 116** 98 to 117** 106** 95 to 124 113 80 to 117 105 94 to 113 103 Total Density (pcf) 120 to 129 128 112 to 137 125 112 to 127 122 104 to 115** 109** 123 to 129 129** 118 to 131 124 99 to 132 120 113 to 126 125 113 to 130 121 Tar Content (%) NA NA NA NA 4.6 to 16.6 11 4 to 10* 5* NA NA NA NA 1.1 to 19 13 3.1 to 9.9 4.1 13 to 30* 19* Fines Content (%) 10 to 47** 40** 62 to 86 68 8 to 38 16 55 to 68** 60** 10 to 40 * 13* 60 to 75* 70* 2 to 46 11 55 to 67** 60** 36 to 98** 77** Specific Gravity 2.5 to 2.68* 2.67* 2.66 to 2.70* 2.68* 2.44 to 2.71** 2.66** 2.66 to 2.86* 2.68* 2.65 to 2.68* 2.67* 2.66 to 2.70* 2.68* 2.44 to 2.69 2.66 2.44 to 2.86* 2.68* 2.65 to 2.76* 2.7* Liquid Limit (%) NP NP 35 to 71 38 NP NP NP to 49** NP** NP NP NP to 50* 30* NP NP NP to 44** NP** NP** NP** Plasticity Index (%) NP NP 15 to 39 20 NP NP NP to 28** NP** NP NP NP to 30* 15* NP NP NP to 16** NP** NP** NP** Expansion (%) NA NA 0 to 1* 1.0* NA NA 0.06 to 0.30* 0.30* NA NA 0 to 1* 1.0* NA NA 0.06 to 0.3* 0.30* 0.02 to 0.06* 0.06* Collapse (%) 0.01 to 0.04* 0.04* NA NA 0 to 0.13* 0.13* NA NA 0.01 to 0.04* 0.04* NA NA 0.00 to 0.13** 0.13** 0.00 to 0.16** 0.16** 0.00 to 0.02** 0.02** Degree of Saturation (%) # 52 to 100 87 67 to 100 89 71 to 93** 85** 51 to 74 62 91 to 100* 100* 71 to 85 79 10 to 93 30 44 to 100 78 51 to 99 78 Void Ratio 0.49 to 0.57 0.52 0.37 to 0.90 0.61 0.51 to 1.06** 0.57** 0.74 to 0.86** 0.80** 0.40 to 0.48** 0.44** 0.41 to 0.69 0.57 0.33 to 0.76 0.45 0.41 to 0.74 0.52 0.46 to 0.76 0.61 Effective Friction Angle from Direct Shear Test 3 (degrees)

NA NA 14 to 32** 22** 14 to 31** 17** 16** 16** NA NA NA NA 12 to 35 29 30** 30** NA NA


NA NA 400 to 1,000** 800** 550 to 1,700** 550** 1,800** 1,800** NA NA NA NA 0 to 1,700 375 700** 700** NA NA




Range = 0 to 3,000 (Design Value = 550) 1,350** (Design Value = 1,350**)




Range = 100 to 1,050 (Design Value = 250) 100** (Design Value = 100**)

Unconfined Compressive Strength (psi)

NA Range = 28 to 96 (Design Value

= 62)

Young’s Modulus from SPT Correlation 5 (ksf)

158 to 900 246 85 to 752 234 158 to 900 246 85 to 752 234 394 to 1,740 1,112 155 to 756 419 394 to 1,740 1,112 155 to756 419 281 to 906* 349*


1,667** 1,667** 1,209 to 1,650**

1,430** 1,667** 1,667** 1,209 to 1,650** 1,430** 1,257 to 8,833 2,641 1,867** 1,867** 1,257 to 8,833 2,641 1,867** 1,867** 2,463** 2,463**

Poisson’s Ratio Range = 0.33 to 0.38 (Design Value = 0.35) Hydraulic Conductivity (ft/day) 7 10-2 to 103 * 100* 10-7 to 10-1* 10-5* 10-3 to 10-1* 10-2* 10-7 to 10-3* 10-5* 10-1 to 50* 1* 10-7 to 10-1* 10-5* 10-3 to 10-1* 10-2* 10-7 to 10-3* 10-5* 10-8 to 103* 10-5* Compression Index (Cc) 0.03 to 0.06* 0.05* 0.04 to 0.15* 0.10* 0.031 to 0.116** 0.060** 0.1 to 0.12* 0.11* 0.03 to 0.06* 0.05* 0.04 to 0.15* 0.10* 0.031 to 0.116 0.060 0.05 to 0.133** 0.091** 0.052 to 0.195** 0.132**

Recompression Index (Cr) 0.004 to 0.03* 0.02* 0.005 to 0.04* 0.02* 0.002 to 0.021** 0.010** 0.01 to 0.02* 0.015* 0.004 to 0.03* 0.02* 0.005 to 0.04* 0.02* 0.001 to 0.014 0.009 0.004 to 0.086**

0.045** 0.009 to 0.037** 0.028**

At-rest Soil Pressure Coeff., Ko 0.48 to 0.59* 0.53* 0.58 to 0.73** 0.63** 0.580 to 0.72** 0.66** 0.49 to 1.12** 0.81** 0.48 to 0.59* 0.53* 0.58 to 0.73* 0.63* 0.37 to 0.72 0.64 0.50 to 1.12** 0.67** 0.4 to 0.6* 0.5*


Table 2-2: Engineering Properties of Principal Geologic Units (for Wilshire/Fairfax Station) (continued)

Geologic Formation Younger Alluvium (Qal)/Older Alluvium (Qalo) /Lakewood

Formation (Qlw)

Tar Impacted- Younger Alluvium (Qal)/Older Alluvium (Qalo) /Lakewood

Formation (Qlw) San Pedro Formation (Qsp)

Tar-Impacted San Pedro Formation (Qsp)

Tar-Impacted Fernando Formation (Tf)

Predominant Grain Size Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Fine-Grained

USCS Soil Classification SM, SC, SP-SM, SP, SW, GW ML, CL,CH, CL-ML SM, SC ML, CL SC CL,ML GM, SC, SM, SP-SM,SP,SW-

SM ML Siltstone

Unconfined Compressive Strength (psi)

NA NA 10 to 100* 50* NA NA 50 to 100* 75* NA NA 10 to 100* 50* NA NA 50 to 100* 75* 28 to 96 62

Soil Abrasion Test Value 15 to 35* 30* 1 to 12* 3* 20 to 40** 30** 1 to 12* 3* 15 to 35* 30* 1 to 12* 3* 20 to 35 25 1 to 12* 3* 2 to 6.5* 4* Corrosivity Results: 8 Minimum Resistivity (ohm-cm) 390 to 3,600** 390** 480 to 720* 480* 560 to 26,400** 560** 520 to 920** 520** 390 to 3,600* 390* 480 to 720* 480* 800 to 26,400 800 520 to 920** 520** 220 to 2,560** 220** pH 2 to 8.2** 2** 3.7 to 8.4* 3.7* 2.6 to 7.7** 2.6** 6.8 to 8.2** 6.8** 2 to 8.2* 2* 3.7 to 8.4* 3.7* 2.6 to 7.7 2.6 6.8 to 8.2** 6.8** 3.0 to 7.6** 3.0** Chloride Content (ppm or mg/kg) 6 to 142** 142** 4 to 139* 139* 1 to 49** 49** 7 to 46** 46** 6 to 142* 142* 4 to 139* 139* 1 to 141 141 7 to 264** 264** 90 to 2,776** 2,776** Sulfate Content (ppm or mg/kg) 63 to 8,075** 8,075** 3.5 to 3,075* 3,075* 81 to 8,790** 8,790** 362 to 1,600** 1,600** 63 to 8,075* 8,075* 3.5 to 3,075* 3,075* 81 to 833 833 362 to 1,810** 1,810** 530 to 5,897** 5,897**

*No test data; reported values are based on data from adjacent stations and reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience ** Limited data; reported values are based on data at the station and that from adjacent station and reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience “NP” indicates non-plastic material # Estimated using assumed specific gravity of 2.65 when a specific gravity test was not performed “NA” indicates engineering property not applicable for the material type or no test data pcf = pounds per cubic foot; psf = pounds per square foot; psi = pounds per square inch; cm = centimeter; ppm = parts per million; mg = milligrams; kg = kilograms Notes: 1. Data presented here are based on ACE, PE and Adv. PE phase explorations as well as applicable prior explorations as discussed in Tunnel GDRs 2. Blow counts from environmental hollow-stem-auger borings were not considered 3. Effective cohesion and friction angle are based on yield values from slow direct shear tests. See figure in Appendix E of Wilshire/La Brea GDR on how yield values were picked. 4. Cohesion and friction angle are based on peak shear strength values from Triaxial consolidated-undrained tests. Effective values are based on effective stress and undrained values are based on total stress 5. Based on relationship between elastic modulus and SPT N1,60 from Sabatini et al., (2002, P.148) 6. Based on secant modulus computed at 0.1+0.05% axial strain from Triaxial consolidated-undrained tests 7. Hydraulic conductivity values were based on published data (Department of Water Resources Bulletin 118, California’s Groundwater Update, 2003) and packer testing at nearby exploratory shaft site 8. For soil corrosivity, the design values correspond to minimum resistivity, lowest pH and highest values for chloride and sulfate content




Table 2-3: Engineering Properties of Principal Geologic Units (for Wilshire/La Cienega Station)

Geologic Formation Younger Alluvium (Qal) + Older Alluvium (Qalo) San Pedro Formation (Qsp)

Predominant Grain Size Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained

USCS Soil Classification SW, SP, SM, SC CL, CH, ML, CL-ML SW, SW-SM, SP, SP-SM,

SM, SC CL, CL-ML, CH, ML,

MH





SPT Blowcounts 2 16 to 30 20 8 to 19 12 8 to 50+ 26 9 to 50+ 17 Moisture Content (%) 7 to 27 15 9 to 39 26 11 to 43 19 10 to 46 26 Dry Density (pcf) 96 to 122 116 80 to 112 98 78 to 120 106 78 to 114 96 Total Density (pcf) 113-138 133 108-134 123 93 to 135 127 113-132 122 Fines Content (%) 5 to 22** 22** 64 to 95** 75** 11 to 49 34 51 to 98 69

Specific Gravity 2.65 to 2.68* 2.67* 2.6 to 2.77**

2.77** 2.53 to 2.78 2.73 2.61 to 2.79

2.68

Liquid Limit (%) NP to 31** 16** 37 to 59 42 NP to 46 41 NP to 78 48 Plasticity Index (%) NP to 9** 5** 15 to 40 24 NP to 28 21 NP to 45 27 Expansion (%) NA NA 0 to 1* 1.0* NA NA 0 to 1* 1.0*

Collapse (%) 0.01 to 0.04* 0.04* NA NA 0.00 to 0.15 0.15 0.00 to 0.15

0.15

Degree of Saturation (%) # 50 to 81** 81** 85 to 89** 87** 44 to 100 97 77 to 100 94

Void Ratio 0.5 to 0.6** 0.6** 0.615 to 0.662**

0.639** 0.515 to 1.160

0.643 0.472 to 1.152

0.73

Effective Friction Angle from Direct Shear Test 3 (degrees)

NA NA 12 to 19** 16** 8 to 35 28 9 to 29 21


NA NA 500 to 900**

700** 0 to 3,200 925 300 to 2,300

950


Range = 29.5 to 36 (Design Value = 35)


Range = 300 to 650 (Design Value = 350)






398 to 1,013 612 74 to 458 171 135 to 1,165 447 56 to 562 167


NA NA NA NA 2,191** 2,191** 1,013 to 2,200

1,963

Poisson’s Ratio Range = 0.3 to 0.4 (Design Value = 0.36) Hydraulic Conductivity (ft/day) 7

10-2 to 500 50 10-7 to 10-1 10-5 10-2 to 500 50 10-7 to 10-1 10-5

Compression Index (Cc) 0.043 to 0.06**

0.06** 0.03 to 0.15

0.06 0.05 to 0.10 0.07 0.04 to 0.12

0.09

Recompression Index (Cr) 0.006 to 0.01**

0.01** 0.01 to 0.03

0.01 0.01 to 0.02 0.01 0.01 to 0.05

0.02

At-Rest Lateral Soil Pressure Coeff., Ko

0.41 to 0.56* 0.49* 0.62 to 0.8**

0.8** 0.4 to 0.6** 0.6** 0.6 to 0.8 0.70

Unconfined Compression (psi)

NA NA 10 to 100* 50* NA NA 10 to 100* 50*

Soil Abrasion Test Value 6 to 24* 9* 1 to 12* 3* 5.9 to 23.5 9.4 1 to 12* 3*


Table 2-3: Engineering Properties of Principal Geologic Units (for Wilshire/La Cienega Station) (continued)

Geologic Formation Younger Alluvium (Qal) + Older Alluvium (Qalo) San Pedro Formation (Qsp)


USCS Soil Classification SW, SP, SM, SC CL, CH, ML, CL-ML SW, SW-SM, SP, SP-

SM, SM, SC CL, CL-ML, CH,

ML, MH

Corrosivity Results: 8

Range

Design Value

Range Design Value

Range Design Value

Range Design Value

Minimum Resistivity (ohm-cm) 390 to 3,600* 390* 1,760 to 2,000**

1760** 600 to 1,240**

600** 480 to 1,240

480

pH 2 to 8.2* 28.2* 7.4 to 8** 7.4** 7.9 to 8.1**

7.9** 7.6 to 8.2

7.6

Chloride Content (ppm or mg/kg) 6 to 142* 142* 4 to 20** 20** 9 to 33** 33** 11 to 131

131

Sulfate Content (ppm or mg/kg) 50 to 150* 150* 50 to 702** 702** 316 to 1,002**

1,000** 47 to 1,120

1,120

*No test data; reported values are based on data from adjacent reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience ** Limited data; reported values are based on data at the station and that from adjacent reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience “NP” indicates non-plastic material # Estimated using assumed specific gravity of 2.65 when a specific gravity test was not performed “NA” indicates engineering property not applicable for the material type or no test data pcf = pounds per cubic foot; psf = pounds per square foot; psi = pounds per square inch; cm = centimeter; ppm = parts per million; mg = milligrams; kg = kilograms Notes: 1. Data presented here are based on ACE, PE and Adv. PE phase explorations as well as applicable prior explorations as discussed in Tunnel GDRs 2. Blow counts from environmental hollow-stem-auger borings were not considered 3. Effective cohesion and friction angle are based on yield values from slow direct shear tests. See figure in Appendix E of Wilshire/La Brea GDR on how yield values were picked. 4. Cohesion and friction angle are based on peak shear strength values from Triaxial consolidated-undrained tests. Effective values are based on effective stress and undrained values are based on total stress 5. Based on relationship between elastic modulus and SPT N1,60 from Sabatini et al., (2002, P.148) 6. Based on secant modulus computed at 0.1+0.05% axial strain from Triaxial consolidated-undrained tests 7. Hydraulic conductivity values were based on published data (Department of Water Resources Bulletin 118, California’s Groundwater Update, 2003) and site-specific pumping test data for Wilshire/La Cienega Station 8. For soil corrosivity, the design values correspond to minimum resistivity, lowest pH and highest values for chloride and sulfate content




3.0 DYNAMIC SITE CHARACTERISTICS

3.1 Response Spectra Response spectra were developed for the underground station boxes and the at‐grade ancillary structures in accordance with Sections 2.3.1 through 2.3.3 of the Metro Rail Seismic Design Criteria (Metro Seismic Criteria, May 20132012). Two hazard levels were evaluated as listed below, assuming a design life of 100 years for structures per the Metro Seismic Criteria.

Operating Design Earthquake (ODE) – defined as an earthquake event likely to occur only once in the design life, where structures are designed to respond without significant structural damage. The current Metro Code defines ODE as an event with a 50% probability of exceedence in 100 years (corresponding to a return period of 150 years).

Maximum Design Earthquake (MDE) – defined as an earthquake event with a low probability of occurring in the design life, where structures are designed to respond with repairable damage and to maintain life safety. The current Metro Code defines MDE as an event with a 4% probability of exceedence in 100 years (corresponding to a return period of 2,475 years)

The response spectra for the ODE and MDE events were estimated using the 2008 USGS Interactive Probabilistic Seismic Hazard Analysis (PSHA) Deaggregation tool on the USGS website (USGS, 2011). The USGS deaggregation tool uses the Next Generation Attenuation (NGA) relationships of Boore‐Atkinson (2008), Campbell‐Bozorgnia (2008) and Chiou‐Youngs (2008) for the ground motion prediction equations. Based on the available combinations of exceedence probability and exposure time, ground motions for the MDE event were computed for a probability of exceedence of 2% in 50 years (equivalent to the 4% in 100 year criteria, as stated in the Metro Design Criteria).

Site‐specific seismic shear wave data of the subsurface soils was available from several seismic CPTs (SCPT) and p‐and s‐wave suspension logging data obtained in soil borings. The information pertaining to the SCPTs and borings used for evaluation of response spectra ate presented in Table 3‐1.

The spectral ordinates of the 5% damped response spectra for both ODE and MDE events, for station box and ancillary structures, are presented in Table 3‐1. For Vs,30 of less than 1,200 feet per second (for the earth materials beneath foundations of both the ancillary structures and station box), a Site Class D may be used for seismic design.

3.2 Time Histories and Spectral Matching In order to evaluate the free‐field displacement for racking analysis, it was required to perform a site‐specific site response analysis. For this purpose, spectrum‐compatible time histories were developed using the 5% damped ODE and MDE response spectra. The target response spectra for the ODE and MDE events were computed for a stiff soil/soft rock type site condition with an average velocity, (Vs,30) of 1,837 feet per second (560 meters per second) assumed to be at a depth of about 150 feet bgs for all three stations. The target response spectra are presented in Appendix A.

Recorded seed time histories from prior earthquakes are generally selected so that the earthquake magnitudes, source‐to‐site distance, fault mechanism and subsurface site conditions of the recording stations are similar to that of the site conditions and the earthquakes anticipated at the stations.


Three time histories were obtained from the Pacific Earthquake Engineering Research (PEER) Center, Next Generation Attenuation (NGA) ground motion database for shallow crustal earthquakes in active tectonic regimes. The time histories were selected based on the following factors: geologic and soil characteristics, inclusion of strong directivity or near‐source ground motions, and the results of de‐aggregation of probabilistic seismic hazard. Based on the de‐aggregation results, the controlling earthquakes for the ODE event have a Magnitude range of 6.6 to 7.1 at a distance of 3.5 to 11.0 kilometers, and for the MDE event, a Magnitude range of 6.7 to 7.1 at a distance of 15 to 30 kilometers. It is noted that the three faults closest to the station are the Hollywood (Mw = 6.7), Santa Monica (Mw = 6.6 to 6.8) and Raymond (Mw = 6.8) Faults which primarily have strike‐slip fault mechanisms (with some component of reverse mechanism).

The three time histories selected for spectral matching are presented in Table 3‐2. Also listed in the table are the site conditions, fault mechanisms and source‐to‐site distances for each of the recording stations.




Table 3-1: Acceleration Response Spectra for Stations and Ancillary Structures

Earthquake Level

Latitude (degrees)

Longitude (degrees)

Formations Vs,30 1

(feet/second) Period (sec):

5% Spectral Accelerations (Sa, in g)

0.01 0.10 0.20 0.30 0.50 1.00 2.00

Wilshire/La Brea Station Box Structure and Ancillary Structures2 (Site Class D)

ODE

34.0622 -118.3429

Younger/Older Alluvium and San Pedro/

Fernando

1,200

Sa (g): 0.29 0.54 0.67 0.63 0.51 0.30 0.14

MDE Sa (g): 0.85 1.53 1.93 1.92 1.68 1.02 0.48

Wilshire/Fairfax Station Box Structure and Ancillary Structures3 (Site Class D)

ODE

34.0630 -118.3610

Younger/Older Alluvium and San Pedro/

Fernando

1,080 to 1,150

Sa (g): 0.29 0.54 0.67 0.63 0.51 0.30 0.14

MDE Sa (g): 0.85 1.53 1.93 1.92 1.68 1.02 0.48

Wilshire/La Cienega Station Box Structure4 (Site Class D)

ODE 34.0648 -118.3747 San Pedro 1,100

Sa (g): 0.30 0.53 0.68 0.66 0.55 0.33 0.16

MDE Sa (g): 0.86 1.49 1.88 1.91 1.76 1.15 0.58

Wilshire/La Cienega Ancillary Structures4 (Site Class D)

ODE 34.0648

-118.3747

Younger/Older Alluvium and San Pedro

820

Sa (g): 0.30 0.51 0.66 0.66 0.57 0.37 0.19

MDE Sa (g): 0.78 1.28 1.65 1.72 1.62 1.16 0.64

1 Vs,30 = shear wave velocity within the 30 meters of earth material below the station bottom or within the 30 meters of material below ground surface for ancillary structures. 2 For Wilshire/ La Brea, shear-wave data is based on seismic measurements from CPT C-110 and p- and s-wave suspension logging data in Boring G-308 3 For Wilshire/ Fairfax, shear-wave data is based on seismic measurements from p- and s-wave suspension logging in Borings G-312 and G-319. 4 For Wilshire/ La Cienega, shear-wave data is based on seismic measurements from CPTs C-112, C-302 and C-303


Table 3-2: Seed Time Histories

Time History Designation

Name

Earthquake

Magnitude

(Mw)

Fault Mechanism

Recording

Station

Closest Distance to Fault

(km)

Recording Component (degrees)*

Recording Station Vs,30 (feet/second)

Site Conditions

NGA_825-090 1992 Cape Mendocino

7.01 Reverse CDMG 89005

Cape Mendocino 6.96 090 514

About 15 feet of soil overlying rock

NGA_983_292 1994

Northridge 6.69 Reverse

USGS 655 Jensen Filter Plant Generator

5.43 292 1726 Rock

NGA_1111_090 1995 Kobe 6.90 Strike-Slip CUE 99999 Nishi-Akashi

7.08 090 1998 Up to 60 feet of

stiff soil overlying rock

*000 – NS, 090 – EW

Spectral matching of the seed time histories was performed in the time domain by adding or subtracting wavelets of limited duration to the original time history using the algorithms from program RSPMATCH (Abrahamson, 1998) incorporated into EZ‐FRISK. A more detailed description of the time histories selected for the project and the spectral matching is presented in Appendix A.

3.3 Site Response Analysis and Free-Field Differential Displacement Site response analyses were performed using the one‐dimensional equivalent linear program SHAKE91 (Idriss and Sun, 1992) to estimate free‐field displacement of the soil column between the top and bottom of the station box. Site response analyses were performed using ground motions for ODE and MDE events following the Metro Seismic Criteria for design using two hazard levels.

Seismic shear wave velocities of the subsurface soils available from seismic CPTs and suspension logging in drilled boreholes were used in developing the one‐dimensional soil profile and dynamic properties of different soil layers. A 150‐foot thick soil column was considered in the one‐dimensional model. Based on available geologic information, the shear‐wave velocity was determined to be 1,837 feet per second (560 meters per second) for the transmitting base at a depth of 150 feet bgs.

Three appropriate spectrum‐matched acceleration time histories, as discussed in Section 3.2, were used as the input outcropping motions in the model. The time histories of shear strains were obtained in each of the layers within the zone of interest (between the top and bottom of the box) for the station racking and then the displacement time histories were computed in these soil layers. The equivalent displacement time history within the zone of interest was estimated by adding displacement time histories in each of these layers. The peak value in the displacement time history was taken as the estimated peak free‐field displacement between the top and bottom of the station box. The free‐field maximum differential displacements computed for the ODE and MDE events in this manner are presented in Table 3‐3. The values in the table may be linearly extrapolated for other structure heights.




Table 3-3: Free-Field Displacement (ODE and MDE)

Station Name Free-Field Displacement (inches)

ODE MDE

Wilshire/La Brea 0.25 inch in 50 feet 2.25 inch in 50 feet

Wilshire/Fairfax 0.250.4 inch in 50 feet 1.70 inch in 50 feet

Wilshire/La Cienega 0.36 inch in 50 feet 2.40 inch in 50 feet

During the Adv. PE phase, p and s‐wave suspension logging was performed in Borings G‐308 (at the Wilshire/La Brea Station). During the Adv. PE phase, two additional seismic CPTs C‐302 and C‐303 were performed at the Wilshire/La Cienega Station. Due to similar shear wave velocity profiles obtained in the PE Phase and Adv. PE data, a revised site response analysis is not considered to be necessary at the Wilshire/La Brea and Wilshire/La Cienega Stations and the reported values of free‐field displacement in Table 3‐3 are considered valid.

In 2013, additional shear‐wave velocity data was obtained by performing p and s‐wave suspension logging in borings G‐312 and G‐319 at the Wilshire/Fairfax station. Based on the new data, it was considered necessary to revise the one‐dimensional soil column in the site response analysis; the free‐field displacement values presented in the table above for the Wilshire/Fairfax station are based on the revised analysis. Furthermore, a two‐dimensional finite element analysis was performed for the Fairfax station using QUAD4m to account for wave scattering effects around the station opening and to obtain acceleration and displacement time histories. In addition, a dynamic two‐dimensional analysis was performed in FLAC to obtain seismic spring stiffnesses for structural racking analysis of the station. The details of the two‐dimensional analyses performed for the Wilshire/Fairfax Station are presented in Appendix A. Dynamic Spring Stiffness

Lateral and vertical soil spring stiffnesses were estimated for use in two‐dimensional and/or three‐dimensional structural analysis of the station boxes. The lateral springs can be used to model the stiffness of the soils retained by the below grade walls of the stations, both in the longitudinal and transverse directions. The vertical springs can be used to model the soils supporting the station foundations.

3.3.1 Lateral Spring Stiffness

The lateral stiffnesses were estimated using equations published in FEMA 356/ASCE 41 for foundations in translation in the x‐ and y‐directions. The method uses the shear wave velocity, shear modulus, Poisson’s ratio of the surrounding medium and station box dimensions (length, width and height) in estimating the spring stiffness.

For the ODE and MDE events, small‐strain shear wave velocity was degraded by about 15% and 45% (for Wilshire/La Brea and Wilshire/La Cienega Stations), respectively, using the guidelines provided in Table 19.2‐1 of FEMA P‐ 750 (2009). Correspondingly, for the ODE and MDE events, small‐strain shear wave velocity was degraded by about 20% and 68% for Wilshire/Fairfax Station. Based on the small‐strain shear wave velocity of the soils, a Site Class C/D was used in computing the degradation factor. Due to the variation of shear wave velocity with depth and along the length of the station box, a range (lower‐bound and upper‐bound) and a best estimate of the shear wave velocity were used in spring stiffness


computations. The estimated average lateral spring stiffness for small‐strain, ODE and MDE events are presented in Table 3‐4. In addition, for the Wilshire/Fairfax Station, there are dynamic spring stiffness values developed using two dimensional analyses presented in Appendix A. Depending on the direction of the structural analysis performed (longitudinal or transverse), the spring stiffness in kips per cubic foot (kcf) may be multiplied by the station box side area to estimate the spring stiffness in units of kips per foot (kip/ft).

Table 3-4: Lateral Soil Spring Stiffness for Arch Module (Small Strain, ODE and MDE)

Value Small Strain ODE MDE Small Strain ODE MDE

Kx (kcf)a Kx (kcf)a Kx (kcf)a Ky (kcf)b Ky (kcf)b Ky (kcf)a

Wilshire/La Brea Station Average 23z 16z 7z 1.7z 1.3z 0.5z Upper Bound 37z 27z 11z 2.8z 2.1z 0.8z Lower Bound 12z 9z 4z 1z 0.7z 0.3z

Wilshire/Fairfax Station* Average 16z 10z 2z 1.5z 0.9z 0.2z Upper Bound 11z 7z 12z 1z 0.6z 0.1z Lower Bound 27z 17z 3z 2.4z 1.5z 0.2z

Wilshire/La Cienega Station Average 15z 10z 2z 1.2z 0.7z 0.1z Upper Bound 39z 25z 4z 3.0z 1.9z 0.3z Lower Bound 5z 3z 1z 0.4z 0.2z 0.1z a Distribute over area of end wall (width * height), unit stiffness increases with depth (z, depth below ground surface in feet) b Distribute over area of side wall (length * height), unit stiffness increases with depth (z, depth below ground surface in feet) *Dynamic spring stiffness values based on site specific two dimensional analysis are presented in Appendix A

The variable “z” in Table 3‐4 is depth below ground surface. Spring stiffness above the top of the station walls should be ignored. The x‐axis and y‐axis are oriented in the length and width directions of the station box, respectively; Kx and Ky represent springs in the x‐ and y‐directions. For the computations presented herein, the length and width of the station box presented in Table 1‐1 were used. The approximate top of the station box wall for the arch roof module are also presented in Table 1‐1. It is noted that the spring stiffness presented in the above table will need to be revised if the station dimensions change significantly.

As stated earlier, only about 15 to 20% degradation from the small‐strain value is estimated for the ODE event, therefore it is suggested that the spring stiffness values estimated for the ODE event be used for the static condition as well. If the MDE case is analyzed, the respective spring stiffness values presented in Table 3‐4 should be used.

The dynamic spring stiffnesses provided herein are based on shear wave data which are not affected by the presence of groundwater, except possibly by pore pressures generated in soil during earthquakes. Dynamic spring stiffnesses provided herein are applicable for both current and design (historically‐highest) groundwater conditions. Furthermore, liquefaction hazard at the station locations is considered low and therefore, the dynamic lateral spring stiffnesses presented in Table 3‐4 are not anticipated to be reduced any further.




3.3.2 Vertical Spring Stiffness

Vertical stiffness was computed using equations published in FEMA 356/ASCE 41 for translation in the z‐direction. Soil shear wave velocities below the station bottom were used in estimating the vertical stiffness. Due to the variation of shear wave velocity with depth below the station foundation and along the length of the station box, a range (lower‐bound and upper‐bound) and a best estimate of the shear wave velocity were used in spring stiffness computations.

For the ODE and MDE events, small‐strain shear wave velocity was degraded by about 15% and 45% (for Wilshire/La Brea and Wilshire/La Cienega Stations), respectively, using the guidelines provided in Table 19.2‐1 of FEMA P‐ 750 (2009). Correspondingly, for the ODE and MDE events, small‐strain shear wave velocity was degraded by about 20% and 68% for Wilshire/Fairfax Station. Based on the small‐strain shear wave velocity of the soils, a Site Class C/D was used in computing the degradation factor.

Table 3‐5 provides lower bound, upper bound and average vertical stiffnesses for small strain, ODE and MDE events. In addition, for the Wilshire/Fairfax Station, there are vertical spring stiffness values developed using two dimensional analyses presented in Appendix A. The spring stiffness in kips per cubic feet (kcf) may be multiplied by the mat foundation area to estimate the spring stiffness in units of kips per foot (kip/ft). For the computations presented herein, the length and width of the station box foundation were assumed to be about 1000 feet and 60 feet, respectively. It is noted that the spring stiffness presented in the above table will be need to revised, if the station dimensions change significantly.

4.0 DESIGN AND CONSTRUCTION

This section provides a summary of the geotechnical evaluation of the subsurface conditions at the station sites and their impact on the design and construction of the proposed stations and ancillary structures.

4.1 Geotechnical Considerations Based on the plan and profile dated May 2013, the stations will be excavated within Younger alluvium and Quaternary‐age‐Older alluvium and Lakewood Formation, and Pleistocene‐age San Pedro Formations. The soils in these formations predominantly consists of medium stiff to stiff clays and silts

Table 3-5: Vertical Spring Stiffness (Small Strain, ODE and MDE)

Value Small Strain

kz (kcf) ODE

kz (kcf) MDE

kz (kcf)

Wilshire/La Brea station

Average 190 135 55

Lower Bound 135 100 40

Upper Bound 255 185 75

Wilshire/Fairfax station*

Average 145 90 15

Lower Bound 100 65 10

Upper Bound 200 125 20

Wilshire/La Cienega station

Average 140 90 15

Lower Bound 75 45 7

Upper Bound 240 150 25 *Dynamic spring stiffness values based on site-specific two-dimentional analysis are presented in Appendix A


interlayered with medium dense to dense silty sands and sands. Excavation in these soils can be performed using conventional earth‐moving equipment. At Wilshire/Fairfax Station, below a depth of about 30 feet, predominantly tar‐impacted soils (either tar sand or petroliferous silts and clays) will be encountered. Difficulties such as sticking of tar to equipment, reduced shear strength of soil under elevated temperatures should be anticipated in operating excavation equipment in the tar‐impacted soils. Although cobbles or boulders were not encountered in the borings, if encountered, these materials can be excavated by conventional earth moving equipment. Due to artesian pressure conditions (discussed in Section 4.2), caving of sands should be anticipated during installation of soldier piles and tieback anchors in sandy deposits particularly under pressurized groundwater conditions.

Certain challenges will have to be addressed in conjunction with station excavation, such as the presence of major utility lines crossing the station footprint and the presence of existing tieback anchors from former basement constructions that protrude into the planned excavation. Based on the project‐specific utility maps, a number of existing utilities such as storm drains, sewers, electrical conduits, and telecommunication lines are located within the upper 10 to 15 feet of ground surface. An existing underground box culvert almost one‐half the width of the La Cienega Boulevard is located immediately west of the station box. All utilities will have to be carefully protected in place or relocated where possible.

4.2 Groundwater Levels

4.2.1 Wilshire/La Brea Station

Groundwater in prior borings drilled in the 1970s and 1980s at the Wilshire/La Brea station location was measured at depths of about 11 to 15 feet bgs. The depth to groundwater in current monitoring wells varies from about 15½ to 18½ feet bgs. Groundwater levels have fluctuated about 5 feet or less based on the measurements obtained over this 40 year period.

4.2.2 Wilshire/Fairfax Station

Groundwater levels as shallow as 12 to 25 feet bgs were reported in prior borings drilled near the Wilshire/Fairfax Station (LeRoy Crandall and Associates, 1983).

Groundwater measurements in the monitoring wells that were screened between depths of 12½ to 70 feet ranged from 12½ to 52½ feet bgs. In the majority of the deeper screened wells (70 to 100 feet bgs) near the station site, groundwater could not be measured due to presence of tar seeps, except for the wells near the La Brea Tar Pit, where groundwater and/or tar seeps were either measured or observed at or near the ground surface.

4.2.3 Wilshire/La Cienega Station

Groundwater measurements in shallow screened [25 to 70 feet below ground surface (bgs)] Adv. PE phase monitoring wells at the Wilshire/La Cienega station site range from 21½ to 29 feet bgs. Groundwater measurements in nearby deeper screened (55 to 100 feet bgs) ACE and PE phase monitoring wells range from about 24 to 54 feet bgs. In addition, water seepage between depths of about 17 to 50 feet bgs has been reported in prior borings drilled near the Wilshire/La Cienega Station (LeRoy Crandall and Associates, 1968 and 1969 ‐ see GDR).




4.2.4 Design Groundwater Level for Three Stations

Groundwater‐level contour maps of the Beverly Hills and Hollywood Quadrangles show the historically highest groundwater levels are at approximately 10 feet (average) below the ground surface at the station locations (CDMG, 1998). The current ground water levels are about 5 to 10 feet lower than the historically highest groundwater level. Considering the design life of the station (100 years), the design groundwater level should be assumed to be at 10 feet bgs for all three Stations.

4.3 Seismic Design Considerations According to the California Geological Survey Liquefaction Hazard Map (CDMG, 1999), the Wilshire/La Cienega station site is located within an area identified as having a potential for liquefaction. Wilshire/La Brea and Wilshire/Fairfax Stations are not located within an area identified as having a potential for liquefaction.

A site‐specific liquefaction evaluation was performed for Wilshire/La Cienega Station using blow count data from borings and data from cone penetration tests. The liquefaction evaluation was performed for the ODE level using a magnitude of 6.5 and a Peak Ground Acceleration (PGA) of 0.35g. Based on the analysis, the potential for liquefaction at the Wilshire/La Cienega Station site is considered to be low.

The estimated PGA and Peak Ground Velocity (PGV) for ODE and MDE events for three Stations are presented in Table 4‐1 through Table 4‐3. The estimated free‐field displacements over the station box height for use in racking analysis of three stations are presented in Table 3‐5.

4.4 Excavation Methods Excavations as deep as 80 feet will be required for the station construction. Due to proximity of station excavation to existing buildings and limited construction space within the public right‐of‐way, shoring will be required. Shoring systems such as soldier piles with wood or shotcrete lagging, secant piles, and slurry walls supported by tieback anchors/and or internal bracing with struts and walers or rakers may be used. However, based on the current plans, the station excavation support will be internally braced with struts. Rakers are anticipated for the construction of the entrance structure

A soldier piles and lagging shoring system may be used, provided the site is properly dewatered. Alternatively, a relatively water‐tight shoring system such as secant/tangent piles or a slurry wall system could be considered.

4.5 Dewatering and Groundwater Control

4.5.1 Parameters Used for Design Estimates

Wilshire/La Brea Station:

The groundwater levels observed during the current investigation are generally consistent with prior investigations performed near the station. The groundwater levels were measured as shallow as 15 feet bgs. The proposed excavation would extend about 55 to 60 feet below the current water levels. Therefore, groundwater control will be required, considering that a conventional soldier pile and wood lagging shoring system is proposed for the project. The principal source of water is expected from the sandy materials of San Pedro formation located between depths of about 55 and 85 feet. Localized seepage should also be anticipated in the upper 55 feet, particularly in the sandier zones.


Wilshire/Fairfax Station:

The groundwater levels observed during the current investigation are generally consistent with prior investigations performed near the station. The groundwater levels were measured as shallow as 12½ feet bgs. However, the groundwater levels in the monitoring wells indicate that “perched” or “semi‐perched” groundwater conditions exist at the station site, as anticipated due to low permeabilities of the tar‐impacted soils which could act as water barriers. The tar‐impacted soils are not expected to yield much water, although water seepages should be anticipated from the perched zones.

Wilshire/La Cienega Station:

The groundwater levels observed during the current investigation are generally consistent with prior investigations performed near the station. The groundwater levels were measured as shallow as 20 feet below ground surface. The proposed excavation would extend about 55 feet below the current water levels. The subsurface geology in the upper 50 feet is highly heterogeneous and is comprised of variable interbedded clays, silts and sand units. The permeable sand encountered at depths of about 50 to 75 feet is anticipated to be the principal source of water to be dewatered during station construction. The groundwater levels in the monitoring wells indicate pressured groundwater conditions in certain water bearing zones. Localized seepage should also be anticipated in the upper 50 feet.

4.5.2 Estimated Groundwater Inflows

A pumping test was performed at the Wilshire/La Brea and Wilshire/La Cienega stations during the PE and Adv. PE phases. Although a pumping test was not performed at the Wilshire/Fairfax station, based on the recent dewatering experience at the exploratory shaft site, a pumping test is not considered to provide useful information about the permeability of tar‐impacted soils. Therefore, a pumping test is not proposed at the Wilshire/Fairfax station at this time.

Wilshire/La Brea Station:

Based on the results of the pumping test performed at the Wilshire/La Brea Station site, water inflow rates of about 200 to 300 gpm are estimated for a 1,000 foot long station excavation. Therefore, it is anticipated that strategically located deep dewatering wells will be required to dewater the site. A qualified dewatering contractor with experience in similar subsurface conditions should be consulted.

Wilshire/Fairfax Station:

As stated earlier, the water level readings in monitoring wells indicate that perched or semi‐perched zones are present. Therefore, groundwater may be confined in certain granular layers and accordingly majority of the inflows will come from these layers. If desired, the contractor could install a pilot dewatering well to evaluate its effectiveness. Based on the prior experience, a water inflow rate on the order of 50 gpm is suggested for use in the preliminary design. A qualified dewatering contractor with experience in similar subsurface conditions should be consulted.

Wilshire/La Cienega Station:

Based on the results of the pumping test performed at the Wilshire/La Cienega Station site, water inflow rates of about 50 to 140 gpm are estimated for a 1,000 foot long station excavation. Therefore, it is




anticipated that strategically located deep dewatering wells will be required to dewater the site. A qualified dewatering contractor with experience in similar subsurface conditions should be consulted.

4.6 Ground Heave and Basal Stability The station sites should be dewatered to maintain the groundwater level at least 5 feet below the excavation bottom to achieve a factor of safety (defined as the ratio of undrained shear strength of base soil to the mobilized undrained shear stress due to dewatering) of 2.0 against basal stability. The soils at the excavation level are predominantly granular and are not expected to heave significantly upon excavation.

4.7 Excavation Support

4.7.1 Geotechnical Design Parameters

The following sections provide general recommendations for the design and construction of shoring braced with internal struts/walers for the station and cantilever shoring walls for ancillary structures. The following sections also provide recommendations for permanent station walls and minor retaining walls.

4.7.2 Lateral Earth Pressures

Shoring:

Shoring up to 80 feet deep will be required for support of station excavation. For structures such as station entrances, 10 to 20‐foot deep shoring will also be required.

For design of braced shoring system (internally braced with struts or tiebacks or both), the use of a trapezoidal distribution of earth pressure is recommended. If a slurry wall system is used, which will serve as both temporary shoring as well as permanent wall, design should be based on at‐rest earth pressures recommended for permanent wall with a trapezoidal earth pressure distribution.

For excavations up to 15 feet or less anticipated for ancillary structures, the use of cantilever shoring may be an economical option. For design of cantilever shoring, a triangular distribution of lateral earth pressure may be used.

Permanent Station Walls and Minor Retaining Walls:

Section 5.6.4 of the Metro Rail Design Criteria states that buried permanent station walls should be designed for lateral at‐rest earth pressures with a triangular distribution considering the long‐term creep of the retained soils. Minor cantilever retaining walls may be designed for active earth pressures with a triangular distribution.

The geotechnical parameters and earth pressure coefficients required for design of shoring and permanent station walls at three stations are presented in Table 4‐1 through Table 4‐3. Recommended earth pressure distributions for design of shoring and permanent walls at three stations are shown in Figure 4‐1.


The earth pressure distributions are presented in Figure 4‐1. These earth pressures assume a level backfill. If the ground surface retained by shoring is sloped, the increase in earth pressure will need to be evaluated on a case‐by‐case basis.

4.7.3 Hydrostatic Pressures

Shoring:

Permeable shoring systems such as soldier pile and lagging system need not be designed for hydrostatic pressures. If shotcrete is used instead of wood lagging, weep holes should be placed to provide drainage of the retained soils. If weep holes are provided, hydrostatic pressures need not be considered in the design. However, if water‐tight shoring systems, such as secant/tangent piles or a slurry wall shoring system is used, hydrostatic pressures as shown in Figure 4‐1, should be added to the lateral earth pressures described above.


Permanent dewatering systems are not expected to be used for the station. Therefore, portions of station walls below design (historically‐highest) groundwater level and the station mat foundation should be designed for hydrostatic pressures. Furthermore, station walls below grade should be waterproofed to avoid intrusion of water and gas into the station.

If minor retaining walls are located below the design water level, the wall should be designed for hydrostatic pressure or be provided with weep holes or drainage behind the wall.

Groundwater levels will fluctuate over time, and since the design life of the subway and the station is 100 years, groundwater levels are expected to raise above current groundwater levels. Therefore, the historically highest water level of 10 feet bgs should be used in computing hydrostatic pressures for design of secant/tangent pile or slurry wall shoring systems which would act as permanent structures, if used.

4.7.4 Surcharge Pressures

Shoring:

Shoring should be designed to resist a uniform lateral pressure of 100 pounds per square foot due to HS20 traffic loading. Applicable surcharge pressures from adjacent buildings and foundations of minor structures should be estimated and added to the earth pressures. Surcharge pressures from heavily loaded construction cranes and other traffic should be added as well.


Applicable lateral and vertical surcharge pressures from adjacent buildings, foundations of minor structures and vehicular loading (HS20) should be estimated and added to the earth pressures stated above. Surcharge pressures from heavily loaded construction cranes and other traffic should be added to the above pressures. Such pressures will be estimated when loading details of the construction traffic are available.

The station roof also should be designed to resist the weight of the overburden soil. The weight of the compacted soil may be estimated using a total unit weight of 125 pounds per cubic foot.




4.7.5 Seismic Earth Pressures

The Metro Seismic Criteria does not provide specific recommendation for computing seismic earth pressures for temporary shoring and permanent walls, but Metro standard drawing SS‐003 presents a guideline for seismic earth pressure due to retained soil and due to adjoining building. Considering that the shoring will be in‐place for more than 2 to 3 years, it is recommended that seismic earth pressure due to retained soil be used for the full height of the shoring and permanent walls. Seismic earth pressure due to adjoining buildings should be in accordance with Metro standard drawing SS‐003 for both shoring and permanent wall and retaining wall design.

The increment of seismic lateral earth pressures due to retained soil should be computed using the seismic earth pressure coefficient increment (ke) provided in Table 4‐1 through Table 4‐3 which was based on PGA for the ODE event. An effective PGA equivalent to half of the computed PGA was used in the computations. The equivalent uniform earth pressure may be computed by taking the same resultant as the triangular equivalent fluid pressure distribution, as shown in Figure 4‐1. Using these design parameters, a seismic earth pressure increment is estimated to be 6H pounds per square foot (uniform), where ‘H’ is the shoring height or the unbalanced permanent wall height, depending on the type of excavation support.

For shoring, this seismic earth pressure is an incremental value intended to be added to the static value, which in this case should be taken as the active earth pressure, not the design shoring lateral earth pressure (K) or the at‐rest earth pressure (K0).

For permanent walls, walls will be need to be designed for both the static (at‐rest pressure) condition, and static plus seismic load combination (with both the seismic increment of lateral earth pressure and the active lateral earth pressure (with a triangular distribution) considered. All required load combinations of static and seismic, with appropriate load factors, should be utilized in the final design of permanent walls.

4.7.6 Design of Soldier Piles

For the design of soldier piles spaced at least two diameters on centers, the allowable lateral bearing value (passive value) of the soils above groundwater level, may be assumed to be 600 pounds per square foot per foot of depth (pcf) below the excavated surface, up to a maximum of 6,000 pounds per square foot. For soils below groundwater level, the allowable lateral value (passive value) of the soils below the level of excavation may be assumed to be 300 pounds per square foot per foot of depth at the excavated surface, up to a maximum of 3,000 pounds per square foot. The passive values include a multiplication factor of 1.5 as recommended by Metro to account for the three‐dimensional effects of the passive wedge. A one‐third increase in the lateral bearing value may be used when considering seismic and other transient loads for ancillary structures.

To develop the full lateral value, provisions should be taken to assure firm contact between the soldier piles and the undisturbed soils. The concrete placed in the soldier pile excavations may be a lean‐mix concrete. However, the concrete used in that portion of the soldier pile, which is below the planned excavated level, should be of sufficient strength to adequately transfer the imposed loads to the surrounding soils.


4.7.7 Lagging

The soldier piles, rakers, struts, and anchors should be designed for the full anticipated lateral pressure. Continuous lagging will be required between the soldier piles. The lagging should be designed in accordance with the drawing for Cut and Cover Underground Structures, titled “Construction Structures Loads and Design Criteria.” If shotcrete is used, weep holes should be provided to relieve hydrostatic pressures.

4.7.8 Anchor Design

Installing tieback anchors in the project area will likely require permission from local agencies and owners of adjacent buildings and avoidance of underground obstruction such as basements, foundations, and utility lines. Tieback anchor in the public right‐of‐way will require removal in accordance with local jurisdiction requirements.

Tieback friction anchors may be used to resist lateral loads. For design purposes, it may be assumed that the failure plane adjacent to the shoring is defined by a plane drawn at 30 degrees with the vertical through the bottom of the excavation (as shown on Metro Rail Structural Standard Cut & Cover Underground Structures Drawing No. SS‐004).

The capacities of anchors should be determined by testing of the initial anchors as outlined on Metro Rail Structural Standard Cut & Cover Underground Structures Drawing No. SS‐004. Pressure‐grouted anchors in the upper 40 feet will develop an average friction value of 1,500 pounds per square foot and a friction value of 2,000 pounds per square foot for anchors below this depth. For anchors 8 inches in diameter, this value corresponds to a bond strength of about 3,000 pounds per lineal foot for anchors in the upper 40 feet and 4,200 pounds per lineal foot for anchors below this depth. Non‐pressure‐grouted anchors in the upper 40 feet will develop an average friction value of 500 pounds per square foot and a friction value of 650 pounds per square foot for anchors below this depth. For anchors 12 inches in diameter, this value corresponds to a bond strength of about 1,500 pounds per lineal foot for anchors in the upper 40 feet and 2,000 pounds per lineal foot for anchors below this depth.




Table 4-1: Geotechnical Design Parameters (Wilshire/La Brea Station)

Parameter

2009 through 2013 Geotechnical and Environmental Investigations

Design Value

Estimated Range of Engineering Parameters 21

Geologic Unit

Lakewood Formation (Qlw) San Pedro Formation (Qsp) Fernando Formation (Tf)

Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained

Dry Unit Weight of Soil (pcf) 1 102 84 to 109 (100) 100 to 120 (108) 85 to 105 (98) 89 to 112 (104) 61 to 97 (84) N/A

Total Unit Weight of Soil (pcf)1 124 114 to 133 (124) 121 to 137 (128) 117 to 129 (122) 116 to 132 (125) 96 to 122 (114) N/A

Static Elastic Modulus based on SPT Correlation (ksf)2a

Varies 68 to 460 (241) 222 to 1047(417) 186 to 674 (388) 189 to 1641 (957) 253 to 754 (418) N/A

Static Elastic Modulus based on Triaxial Test (ksf)2b Varies

1,220 to 1,638 (1,517)

2,178 1,200 to 1,890

(1,545) 3,542 to 4,929

(4,233) 2,540 N/A

Friction Angle (Degrees)3

Field 30 25 to 35 (30)

Saturated 30 26 to 35 (30)

Cohesion (psf) 3

Field 300 0 to 500 (300)

Saturated 250 250 to 300 (250)

Unit Subgrade Modulus (k) (kcf)4 300 (small strain); 240 (ODE); 100 (MDE)

Allowable Bearing Value (psf) 3,0005, 8,0006 N/A

Coefficient of Friction (µ)7 0.36 0.31 to 0.43 (0.36)

Soil Pressure Coefficient, At-Rest K0

Bored Tunnel Section8 0.54 0.38 to 1.01 (0.54)

Underground Station9 0.50 0.43 to 0.56 (0.50)

Soil Pressure Coefficient, Active Ka10 0.30 0.30

Soil Pressure Coefficient, Shoring K11 0.35 0.27 to 0.39 (0.35)

Soil Pressure Coefficient, Passive Kp10 3.2 2.6 to 3.7 (3.2)

Soil Pressure Coefficient, Seismic Ke12 0.10 0.06 to 0.20 (0.10)

Ground surface elevation (ft)13 Varies 196 to 200

Groundwater Elevation (ft) 14 190 186-190 (depth to historically highest groundwater around 10 ft bgs)

178-185 (depth to current groundwater 15.5 to 18.5 ft bgs)

Corrosivity Results15

Minimum Resistivity (ohm-cm) 244 244 to 2,160

pH 4.6 4.6 to 8.4

Chloride Content (ppm or mg/kg) 888 2 to 888

Sulfate Content (ppm or mg/kg) 6,509 44 to 6,509

Poisson's Ratio16

Unsaturated 0.34 0.31 to 0.40 (0.34)

Saturated 0.33 0.30 to 0.36 (0.33)

Liquefaction Potential (Yes or No)14

Above Station bottom No

Below Station bottom No

Dynamic Elastic Modulus (ksf)17

Small Strain (Initial) 16,485 11,740 to 22,040 (16,485)

ODE 11,900 8,480 to 15,925 (11,900)

MDE 4,990 3,550 to 6,670 (4,990)

Shear Wave Velocity (fps)17


ODE 1,090 918 to 1,258 (1,090)

MDE 705 595 to 815 (705)

Peak Ground Accel. (g)- Horiz.18

ODE 0.29 0.29

MDE 0.85 0.85

Peak Ground Velocity (fps)- Horiz19

ODE 1.32 1.32

MDE 4.53 4.53

Free-Field Displacement for Station20

ODE ¼ inch in 50 feet N/A

MDE 2¼ inches in 50 feet

N/A = Not Applicable 1Lab test data from historic, ACE, PE and Adv. PE phase investigations. Use submerged unit weight below design water level 2aBased on relationship between elastic modulus and SPT N1,60 from Sabatini et al, (2002, P.148) 2bBased on secant modulus computed at 0.1+0.05% axial strain from Triaxial consolidated-undrained tests 3Values based on strength test results 4Unit subgrade modulus for design of foundation for service, ODE, and MDE levels 5Spread footing supported on undisturbed natural and/or compacted fill (for minor structures). Increase the values by 30% for short-term seismic (ODE and MDE) and wind loads 6Mat foundation (or) large spread footings. Bearing value may be increased based on the foundation size, if commensurate settlement is acceptable. Increase the values by 30% for short-term seismic (ODE and MDE) and wind load conditions 7Coefficient of friction between mass concrete and subgrade soils 8Based on pressuremeter test results 9Based on site-specific shear strength data 10Active and passive earth pressure coefficients were based on laboratory shear strength data 11Recommended earth pressure coefficient is based on AMEC’s prior experience with similar soils along the alignment 12Based on Mononobe-Okabe (1926, 1929) procedure and PGA for ODE 13Refer to Plate 2-1 of the GDR 14Estimated based on current groundwater level measurements and historic groundwater level data from Seismic Hazard Zone Report for the Hollywood 7.5-minute Quadrangle (1998, revised 2006) and Seismic Hazard Zone Report for the Beverly Hills 7.5-minute Quadrangle (1998, revised 2005) 15Design values are based on lowest resistivity, lowest pH, highest chloride and sulfate content test values 16Possion's Ratio was computed based on Duncan and Bursey (2007), CGPR#44, Virginia Tech 17Small Strain elastic modulus values were based on site-specific shear wave velocity and design Poission's Ratio of 0.35. ODE and MDE values were based on Table 19.2-1 of FEMA P- 750 (2009) 18PGA estimated in accordance with Chapter 2, Section 3 of LA Metro Design Code (2012)


Parameter

2009 through 2013 Geotechnical and Environmental Investigations

Design Value

Estimated Range of Engineering Parameters 21

Geologic Unit

Lakewood Formation (Qlw) San Pedro Formation (Qsp) Fernando Formation (Tf)

Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained 19Based on PGV-S1 correlation (equations 13-1 and 13-2) of FHWA-NHI-10-034 (2009) 20Based on site-specific SHAKE91 analysis 21Average values are shown in parenthesis




Table 4-2: Geotechnical Design Parameters (Wilshire/Fairfax Station)

Parameter 2009 through 2013 Geotechnical and Environmental Investigations

Design Value

Estimated Range of Engineering parameters22

Geologic Unit

Quaternary Younger & Older Alluvium (Qal & Qalo)/Lakewood Formation (Qlw)

Tar-impacted Quaternary Younger & Older Alluvium (Qal & Qalo)/Lakewood Formation

(Qlw) San Pedro Formation (Qsp) Tar-impacted San Pedro Formation (Qsp)

Tar-impacted Fernando Formation (Tf)

Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained

Dry Unit Weight of Soil (pcf) 1 106 87 to 121 (104) 105 to 111 (109) 89 to 95 (92) 82 to 126 (109) 98 to 117 (106) 112 to 118 (116) 80 to 117 (105) 95 to 124 (113) 94 to 113 (103)

Total Unit Weight of Soil (pcf)1 121 112 to 137 (124) 120 to 129 (128) 104 to 115 (109) 112 to 127 (122) 118 to 131

(124) 123 to 129 (126) 117 to 126 (125) 112 to 132 (120) 113 to 126 (120)

Static Elastic Modulus from SPT Correlation (ksf)2a Varies 85 to 752 (234) 158 to 900 (246) 85 to 752 (234) 158 to 900 (246) 155 to 756

(246) 394 to 1740 (1112) 155 to 756 (419) 394 to 1740 (1112) 281 to 906 (349)NA

Static Elastic Modulus from Triaxial Tests (ksf)2b Varies 1,209 to 1,650 (1,430) 1,667 1,209 to 1,650 (1,430) 1,667 1,867 1,257 to 8,833 (2,641) 1,867 1,257 to 8,833 (2,641) 2,463

Friction Angle (Degrees)3

Field 28 24 to 31 (28)

Saturated 27 22 to 30 (27)

Cohesion (psf) 3

Field 300 0 to 500 (300)

Saturated 300 0 to 500 (300)


Allowable Bearing Value (psf) 3,0005, 8,0006

Coefficient of Friction (µ)7 0.32 0.26 to 0.36 (0.32)

Tar Content (% by weight)21 12.1 0.0 to 19 (12.1)

Soil Pressure Coefficient, At-Rest Ko

Bored Tunnel Section8 0.65 0.37 to 1.12 (0.65)

Underground Station9 0.55 0.50 to 0.63 (0.55)


Soil Pressure Coefficient, Shoring K11 0.38 0.33 to 0.45 (0.38)

Soil Pressure Coefficient, Passive Kp10 3.3 3.0 to 4.1 (3.3)

Soil Pressure Coefficient, Seismic Ke12 0.10 0.10 to 0.12 (0.10)

Ground surface elevation (ft)13 Varies 164 to 166

Groundwater Elevation (ft)14 155 155 (depth to historical high ground water around 10 ft bgs)

114.5 to 154.5 (depth to current groundwater 12.5 to 52.5 ft bgs)


Table 4-2: Geotechnical Design Parameters (Wilshire/Fairfax Station) (continued)


Design Value Estimated Range of Engineering parameters21

Geologic Unit


Tar-impacted Quaternary Younger & Older Alluvium (Qal & Qalo)/Lakewood Formation (Qlw)

San Pedro Formation (Qsp) Tar-impacted San Pedro Formation

(Qsp) Tar-impacted Fernando

Formation (Tf)

Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained Fine-

Grained Coarse-Grained

Fine-Grained Coarse-Grained Fine-Grained


Minimum Resistivity (ohm-cm) 520 520 to 26,400

pH 2.62 22.6 to 8.2

Chloride Content (ppm or mg/kg) 264 1.0 to 264

Sulfate Content (ppm or mg/kg) 8,790 81 to 8,790

Poisson's Ratio16

Unsaturated 0.35 0.33 to 0.37 (0.35)

Saturated 0.35 0.33 to 0.38 (0.35)






ODE 9,000 7,000 to 11,200 (9,000)

MDE 1,400 1,100 to 1,750 (1,400)



ODE 950 840 to 1,060 (950)

MDE 380 330 to 420 (380)


ODE 0.29 0.29

MDE 0.85 0.85

Peak Ground Velocity (fps)- Horiz.19




Table 4-2: Geotechnical Design Parameters (Wilshire/Fairfax Station) (continued)


Design Value Estimated Range of Engineering parameters21

Geologic Unit


Tar-impacted Quaternary Younger & Older Alluvium (Qal & Qalo)/Lakewood Formation (Qlw)

San Pedro Formation (Qsp) Tar-impacted San Pedro Formation

(Qsp) Tar-impacted Fernando

Formation (Tf)

Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained Fine-

Grained Coarse-Grained

Fine-Grained Coarse-Grained Fine-Grained

ODE 1.36 1.36

MDE 4.62 4.62

Free-Field Displacement for Station 20

ODE 0.25 inch in 50 feet

MDE 1.7 inches in 50 feet

N/A = Not Applicable 1Lab test data from historic, ACE, PE and Adv. PE phase investigations. Use submerged unit weight below design water level 2aBased on relationship between elastic modulus and SPT N1,60 from Sabatini et al., (2002, P.148) 2bBased on secant modulus computed at 0.1+0.05% axial strain from Triaxial consolidated-undrained tests 3Values based on site-specific strength test results 4Unit subgrade modulus for design of foundation for service, ODE, and MDE levels 5Spread footing supported on undisturbed natural and/or compacted fill (for minor structures). Increase the values by 30% for short-term seismic (ODE and MDE) and wind loads 6Mat foundation (or) large spread footings. Bearing value may be increased based on the foundation size, if commensurate settlement is acceptable. Increase the values by 30% for short-term seismic (ODE and MDE) and wind load conditions 7Coefficient of friction between mass concrete and subgrade soils 8Based on pressuremeter test results 9Based on site-specific shear strength data 10Active and passive earth pressure coefficients were based on laboratory shear strength data. 11Recommended earth pressure coefficient is based on AMEC’s prior experience with similar soils along the alignment 12Based on Mononobe-Okabe (1926, 1929) procedure and PGA for ODE 13Refer to Plate 2-1 of GDR 14Estimated based on current groundwater level measurements and historic groundwater level data from Seismic Hazard Zone Report for the Hollywood 7.5-minute Quadrangle, Los Angeles, California (1998) 15Design values are based on lowest resistivity, lowest pH, highest chloride and sulfate content test values 16Possion's Ratio was computed based on Duncan and Bursey (2007), CGPR#44, Virginia Tech 17Small Strain elastic modulus values were based on site-specific shear wave velocity and design Poission's Ratio of 0.35. ODE and MDE values were based on Table 19.2-1 of FEMA P- 750 (2009) 18PGA estimated in accordance with Chapter 2, Section 3 of LA Metro Design Code (2010) 19Based on PGV-S1 correlation (equations 13-1 and 13-2) of FHWA-NHI-10-034 (2009) 20Based on site-specific SHAKE91 analysis performed during PE phase. 21For tar-impacted soil only 22Average values are shown in parenthesis


Table 4-3: Geotechnical Design Parameters (Wilshire/La Cienega Station)


Design Value

Estimated Range of Engineering Parameters21

Geologic Unit

Quaternary Younger Alluvium (Qal) + Quaternary Older Alluvium (Qalo) San Pedro Formation (Qsp)

Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained

Dry Unit Weight of Soil (pcf) 1 104 80-112 (98) 96-122 (116) 78-114 (96) 78-120 (106)

Total Unit Weight of Soil (pcf)1 126 108-134 (123) 113-138 (133) 113-132 (122) 93-135 (127)

Static Elastic Modulus from SPT Correlation (ksf)2 Varies 74 to 458 (171) 398 to 1,013 (612) 56 to -562 (167) 135 to 1,165 (447)

Static Elastic Modulus from Triaxial Tests (ksf)2b Varies N/A N/A 1,013 to 2,200 (1,963) 2,191

Friction Angle (Degrees) 3

Field 29 23-34 (29)

Saturated 26 19-35 (26)

Cohesion (psf)3

Field 600 500-1050 (600)

Saturated 600 400-600 (600)


Allowable Bearing Value (psf) 3,0005, 8,0006 N/A

Coefficient of Friction (µ)7 0.31 0.22-0.43 (0.31)

Soil Pressure Coefficient, At-Rest Ko

Bored Tunnel Section8 0.67 0.58-0.79 (0.67)

Underground Station9 0.48 0.43-0.67 (0.56)


Soil Pressure Coefficient, shoring K11 0.38 0.27-0.51 (0.38)

Soil Pressure Coefficient, Passive Kp10 3.2 2.64 – 3.87 (3.2)

Soil Pressure Coefficient, Seismic Ke12 0.10 0.0 - 0.20 (0.10)

Ground surface elevation (ft)13 Varies 137 - 140

Groundwater Elevation (ft)14 130 127-130 (depth to historical high ground water around 10' bgs)

117.5 - 118.5 (depth to current groundwater 21.5 - 39.5' bgs)


Minimum Resistivity (ohm-cm) 480 480 - 1,760

pH 7.42 27.4 - 8.2

Chloride Content (ppm or mg/kg) 131 9 - 131

Sulfate Content (ppm or mg/kg) 1,120 47 - 1,120

Poisson's Ratio16

Unsaturated 0.34 0.31 - 0.38 (0.34)

Saturated 0.36 0.30 - 0.40 (0.36)





Small Strain (Initial) 9,005 5,660 - 12,090 (9,005)

ODE 5,675 3,565 -7,620 (5,675)

MDE 905 570 -1,210 (905)


Small Strain (Initial) 945 750 - 1,095 (945)

ODE 745 595 - 865 (745)

MDE 305 240 - 350 (305)


ODE 0.30 0.30

MDE 0.86 0.86

Peak Ground Velocity (fps)- Horiz.19

ODE 1.47 1.47

MDE 5.37 5.37

Free-Field Displacement for Station 20

ODE 0.36 inch in 50 feet

MDE 2.4 inches in 50 feet

N/A = Not Applicable 1Lab test data from historic, ACE, PE and Adv. PE phase investigations. Use submerged unit weight below design water level 2aBased on relationship between elastic modulus and SPT N1,60 from Sabatini et al., (2002, P.148) 2bBased on secant modulus computed at 0.1+0.05% axial strain from Triaxial consolidated-undrained tests

3Values based on strength test results 4Unit subgrade modulus for design of foundation for service, ODE, and MDE levels 5Spread footing supported on undisturbed natural and/or compacted fill (for minor structures). Increase the values by 30% for short-term seismic (ODE and MDE) and wind loads 6Mat foundation (or) large spread footings. Bearing value may be increased based on the foundation size, if commensurate settlement is acceptable. Increase the values by 30% for short-term seismic (ODE and MDE) and wind load conditions 7Coefficient of friction between mass concrete and subgrade soils 8Based on pressuremeter test results 9Based on site-specific shear strength data 10Active and passive earth pressure coefficients were based on laboratory shear strength data. 11Recommended earth pressure coefficient is based on AMEC’s prior experience with similar soils along the alignment 12Based on Mononobe-Okabe (1926, 1929) procedure and PGA for ODE 13Refer to Plate 2-1 of the GDR 14Estimated based on current groundwater level measurements and historic groundwater level data from Seismic Hazard Zone Report for the Hollywood 7.5-minute Quadrangle (1998, revised 2006) and Seismic Hazard Zone Report for the Beverly Hills 7.5-minute Quadrangle (1998, revised 2005) 15Design values are based on lowest resistivity, lowest pH, highest chloride and sulfate content test values 16Possion's Ratio was computed based on Duncan and Bursey (2007), CGPR#44, Virginia Tech 17Small Strain elastic modulus values were based on site-specific shear wave velocity and design Poission's Ratio of 0.35. ODE and MDE values were based on Table 19.2-1 of FEMA P- 750 (2009) 18PGA estimated in accordance with Chapter 2, Section 3 of LA Metro Design Code (2010) 19Based on PGV-S1 correlation (equations 13-1 and 13-2) of FHWA-NHI-10-034 (2009)





Design Value

Estimated Range of Engineering Parameters21

Geologic Unit

Quaternary Younger Alluvium (Qal) + Quaternary Older Alluvium (Qalo) San Pedro Formation (Qsp)

Fine-Grained Coarse-Grained Fine-Grained Coarse-Grained 20Based on site-specific SHAKE91 analysis 21Average values are shown in parenthesis


Figure 4-1: Lateral Pressure Distribution

Notes

1. Flexible walls are assumed to be dewatered or free draining; rigid walls are assumed to be un‐dewatered and water‐tight.

2. Hydrostatic pressures should be used in the design for water‐tight rigid shoring systems such as slurry wall, secant‐pile, tangent‐pile systems and for permanent walls (if not dewatered).

3. For cantilever walls with not dewatered condition, lateral soil earth pressure will be half of the value shown in the figure (i.e., 18.5H); hydrostatic pressures should be added as shown in the figure.

4. For both cantilever and braced shoring and walls, the seismic increment per diagram (d) is to be added to the pressure distribution per diagram (a) or to the pressure distribution per diagram (c) with appropriate load factors, but no less than pressures per diagram (b) with appropriate load factors.

5. The resisting (passive) value includes a multiplication factor of 1.5 as recommended for circular soldier piles per Metro Standard Drawing S‐003; the passive pressure should be modified for other passive‐resisting elements per S‐003 (e.g., a slurry wall system would use the passive values provided divided by 1.5).

6. Below the bottom of excavation, the driving lateral earth pressure need only be applied to the width of the embedded element.




4.7.9 Internal Bracing

Internal struts and walers may be used to internally brace the soldier piles. The strut loads should be determined based on the lateral earth pressures for braced condition as shown in Figure 4‐1. The vertical spacing between the struts should be designed to reduce ground movements. All struts should be tightly fitted to eliminate any slack and to reduce ground movement. If necessary to reduce shoring deflection, a preload of 25% of the design load may be used.

Procedures to compensate for the effects of temperature changes on the strut loads should be developed and implemented so that proper strut load levels can be monitored and maintained during construction.

If used, rakers could be supported laterally by temporary concrete footing (deadmen) or by the permanent interior footings. For design of such temporary footings, poured with the bearing surface normal to the rakers inclined at 45 to 60 degrees with the vertical, a bearing value of 3,000 pounds per square foot may be used, provided the shallowest point of the footing is at least 1 foot below the lowest adjacent grade. To reduce the movement of the shoring, the rakers should be tightly wedged against the footings and/or shoring system.

4.7.10 Deflection

The amount of deflection of a shored embankment is dependent on the flexibility of the shored wall, excavation methods, and spacing of support members such as soldier piles, struts, etc. It should be realized, however, that some deflection will occur. Braced shoring will typically deflect less than tieback shoring. Deflection of braced shoring is highly dependent on strut spacing, strut stiffness, and whether preloading is performed. After the shoring design in finalized, a deflection analysis should be performed to evaluate the lateral deformations of the shoring and associated lateral and vertical deformations of the adjacent ground. Such analysis can be performed using numerical models with FLAC or other commercially available finite‐difference software. Based on the prior experience, deflection of braced shoring is anticipated to be on the order of 1 inch.

If greater deflection than anticipated occurs during construction, additional bracing may be necessary to minimize settlement of the adjacent buildings and utilities in the adjacent streets. If it is desired to reduce the deflection of the shoring, a greater earth pressure could be used in the shoring design, such as a design based on at‐rest pressure condition.

4.7.11 Monitoring

Some means of monitoring the performance of the shoring system is recommended. The instrumentation could consist of inclinometers, ground settlement monuments as well as load cells and strain gages placed on the struts and soldier piles.

The monitoring should consist of periodic surveying of the lateral and vertical locations of the tops and intermediate points of all the soldier piles as well as installation and regular readings of inclinometers. Depending on the proximity of the adjacent structures and utilities, a specific instrumentation and monitoring program should be planned and implemented prior to the commencement of station excavation.


4.8 Gassy Condition Design Considerations The stations will be constructed below current or design groundwater level. It is anticipated that the stations will not be provided with sub drain system or permanent dewatering wells, therefore the station structure will have to be thoroughly waterproofed. In addition, the stations are located within the City of Los Angeles Department of Building and Safety designated “methane zone”. Therefore, an impermeable membrane should be provided against water and/or gas intrusion into the system.

The waterproofing/gas barrier should be used around the entire station box structure as well as for the minor structures such as ramps, stairways, and other ancillary structures that connect to the station.

4.9 Foundations The station bottom is currently planned at a depth of about 65 to 80 feet below ground surface. The soils at the station depths are sufficiently firm to allow support of the station on mat foundation.

Minor structures, such as ramps, stairways, and other structures ancillary to the stations, can be supported on conventional spread footings bearing in properly compacted fill and/or undisturbed natural soils.

The geotechnical parameters for foundation design of station and at‐grade ancillary structures are presented in Table 4‐1 through Table 4‐3.

4.9.1 Bearing Value

Mat foundation for the station, established in stiff and/or dense soils, may be designed to impose a net dead‐plus‐live load pressure of 8,000 pounds per square foot.

Spread footings for minor structures near the existing ground surface that are at least 2 feet wide and at least 2 feet below the lowest adjacent grade or floor level, and are established in properly compacted fill and/or undisturbed natural soils, may be designed to impose a net dead‐plus‐live load pressure of 3,000 pounds per square foot. The excavations should be deepened as necessary to extend into satisfactory soils.

A one‐third increase may be used in the above bearing values for wind or seismic loads. The recommended bearing value is a net value, and the weight of concrete in the footings can be taken as 50 pounds per cubic foot; the weight of soil backfill can be neglected when determining the downward loads.

Since the station excavation extends below groundwater, the bottom of the excavation may be easily disturbed from construction equipment. Therefore, a layer of crushed rock or a waste slab (slurry slab) should be considered to stabilize the subgrade after excavation. Furthermore, a layer of BX1200 geogrid or equivalent could be used in conjunction with the gravel layers to provide additional protection against unstable subgrade conditions, particularly for heavy construction equipment.




4.9.2 Settlement

The average bearing pressure on the station mat foundation is anticipated to be less than the overburden removed by the excavation. Therefore, settlement of the station supported on mat foundation in the manner recommended above is expected to be negligible. Some differential settlement within the mat foundation should be anticipated due to variable soil conditions. Differential settlements are expected to be less than ½ inch in 50 feet.

Settlements of the minor structures supported at‐grade cannot be estimated as the structural loads and foundation details are not available at this time.

4.9.3 Lateral Resistance

Lateral loads can be resisted by soil friction and by the passive resistance of the soils. A coefficient of friction of 0.3 may be used between the foundations and the supporting soils. The passive resistance of undisturbed natural soils against station walls may be assumed to be equal to a uniform pressure of 3,000 pounds per square foot. The structural elements (station walls and the floor decks) should be designed to transfer this load from one side of the box to the other. A coefficient of friction of 0.3 may also be used between the station walls and the supporting soils in resisting the uplift hydrostatic pressures.

The passive resistance of undisturbed natural soils and/or properly compacted fill soils against footings for minor structures may be assumed to be equal to the pressure developed by a fluid with a density of 400 pounds per cubic foot, if above the groundwater level. For soils below the groundwater level, an equivalent fluid pressure of 200 pounds per cubic foot should be used. A one‐third increase in the passive value may be used for wind or seismic loads.

The frictional resistance and the passive resistance of the soils may be combined without reduction in determining the total lateral resistance.

4.9.4 Soil Springs

For the design of mat foundation and soil‐structure interaction (SSI) analysis, soil springs were developed for static and dynamic conditions. The coefficient of subgrade reaction for mat design is presented in Table 4‐1 through Table 4‐3. The recommended dynamic lateral and vertical soil springs for the SSI analysis of the station box are presented in Table 3‐4 and Table 3‐5, respectively. It is noted that the values presented are for the assumed station box dimensions stated in Sections 3.5 and 3.6. If the dimensions change significantly, the soil springs presented in these tables will need to be revised.

4.10 Earthwork Based on the subsurface conditions encountered in the prior and current investigations, the excavation of the station can be accomplished using conventional earth equipment. Earth and site preparation activities for the station construction are expected to consist of the following:

Excavations for shoring elements

Excavation for station box


Subgrade preparation for station mat foundation and near‐surface footings for ancillary structures

Excavations for utility trenches, backfill over station box, footings and utility trenches

Excavation for station and entrance structures will need temporary shoring. All work should be in compliance with applicable City (Los Angeles), State (California) and federal (Occupational Safety and Health Act) requirements.

The on‐site soils excavated from La Brea and La Cienega station excavations may be re‐used as backfill material over the station box, if not contaminated. Majority of the Fairfax station excavation will be made in tar‐impacted soils, which will not be suitable for reuse as backfill material. The on‐site soils are predominantly clayey and will be difficult to compact in confined spaces such as in utility or wall backfill. Import granular material may be required to backfill the excavation should be anticipated.

Any required soil backfill should be placed in loose lifts not more than 8‐inches‐thick and compacted. The fill should be compacted to at least 95% of the maximum density obtainable by the ASTM Designation D1557 method of compaction. The backfill should be sufficiently impermeable when compacted to restrict the inflow of surface water. Some settlement of deep backfill should be allowed for in planning utility connections and overlying concrete hardscape.

4.11 Corrosion Potential To evaluate the potential for deleterious effects of the on‐site soils on structural concrete and steel and on metal piping, chemical testing was performed on selected soil samples. Based on the corrosion test results, the on‐site soils are severely corrosive to ferrous metals, aggressive to copper, and sulfate attack on concrete is considered to be moderate to severe. A corrosion mitigation report prepared by HDR/Schiff Associates is included in Appendix F of the Station GDRs for reference.

5.0 PRIOR EXPERIENCE WITH SIMILAR PROJECTS

AMEC’s predecessor firms LeRoy Crandall and Associates performed numerous geotechnical investigations along Wilshire Boulevard, including several near the Wilshire/Fairfax Station. The building addresses and the excavation and shoring details are presented below.

6100 Wilshire Boulevard

The building has 15 levels above grade and up to 5 subterranean levels for parking. Excavation for basement extended to depths of about 60 feet. Conventional soldier pile with lagging shoring braced with tieback anchors was used for the excavation support. Tieback anchors were designed for a frictional resistance of 700 pounds per square foot in the upper 30 feet and 400 psf in the tar impacted soils.


The building has 4 levels above grade with one subterranean level extending to a depth of 10 feet bgs. The excavation was made by sloping the excavation side walls. Shoring was not used for excavation support.




AMEC’s predecessor firm LeRoy Crandall and Associates also performed numerous geotechnical investigations along Wilshire Boulevard, including several near Wilshire/La Cienega Station. The excavation and shoring details of some of the deeper excavations are presented below.


The building has 10 levels above grade and 3 subterranean levels for parking. Excavation for the basement extended to depths of about 30 feet bgs. Conventional soldier pile with lagging shoring braced with tieback anchors was used for the excavation support.


The building has 10 levels above grade and 4 subterranean levels for parking. Excavation for the basement extended to depths of about 45 feet. Conventional soldier pile with lagging shoring braced with tieback anchors was used for the excavation support.

Based on the results of the pump tests, an inflow rate of 100 gpm was provided in the geotechnical report. Data from monitoring of dewatering pumps for this building indicate that inflow rates were about 10 to 12 gpm between 1972 and 1980. Since 1980, the inflow rates were on the order of 200 to 2,500 gallons per month. This pumping rate is significantly lower than the inflow rate of up to 150 gpm, estimated for Wilshire/La Cienega station dewatering, considering that the station excavation is 30 feet deeper than the building basement and extends into a confined aquifer located at depths of about 50 to 75 feet bgs.

6.0 LIMITATIONS AND BASIS FOR RECOMMENDATIONS

The professional services have been performed using the degree of care and skill ordinarily exercised, under similar circumstances, by reputable geotechnical consultants practicing in this or similar localities. No other warranty, expressed or implied, is made as to the professional advice included in this Technical Memorandum. This TM GDM has been prepared for the Los Angeles County Metropolitan Transportation Authority (Metro) and its design consultants and contractors to be used solely for the evaluation for the Wilshire/La Brea, Wilshire/Fairfax and Wilshire/La Cienega Stations planned as part of the proposed Westside Subway Extension project. The memorandum has not been prepared for use by other parties, and may not contain sufficient information for purpose of other parties or other uses.

In developing this memorandum, AMEC (PB team member) relied on subsurface information obtained during Adv. PE phase and by its predecessor company MACTEC in the AA, ACE, and PE phase studies and its other predecessor companies, Law/Crandall and LeRoy Crandall and Associates, as well as subsurface information obtained by other firms. Subsurface conditions are, by their nature, uncertain and may vary from those encountered at the locations where visual inspections, borings, surveys, or other explorations were made.


7.0 REFERENCES

Abrahamson, N. (1998), Non‐Stationary Spectral Matching Program RSPMATCH, PG&E.

Abrahamson, N.A., and Silva, W.J., 2008, Summary of the Abrahamson & Silva NGA Ground Motion Relations, Earthquake Spectra, Volume. 24, No. 1, pp. 67‐97.

Boore, D.M., and Atkinson, G.M., 2008, Ground‐Motion Prediction Equations for the Average Horizontal Component of PGA, PGV, and 5%‐Damped PSA at Spectral Periods Between 0.01 s and 10.0 s, Earthquake Spectra, Volume 24, No.1, p. 99‐138.

California Geological Survey, 1998 (revised 2005), “Seismic Hazard Zone Report, Beverly Hills 7.5‐Minute Quadrangle, Los Angeles County, California,” Report No. 023.

California Geological Survey, 1998 (revised 2006), “Seismic Hazard Zone Report, Hollywood 7.5‐Minute Quadrangle, Los Angeles County, California,” Report No. 026.

California Geological Survey, 1999, “Seismic Hazard Zone Map, Beverly Hills Quadrangle, Los Angeles County, California,” Map dated March 25, 1999.

California Geological Survey, 1999, “Seismic Hazard Zone Map, Hollywood Quadrangle, Los Angeles County, California,” Map dated March 25, 1999.

Campbell, K.W., and Bozorgnia, Y., 2008, Ground Motion Model for the Geometric Mean Horizontal Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response Spectra for Periods Ranging from 0.01s to 10.0 s, Earthquake Spectra, Volume 24, No.1, pp. 139‐171.

Chiou, B.S.J., and Youngs, R.R., 2008, An NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra, Earthquake Spectra, Volume 24, No.1, pp. 173‐215.

City of Los Angeles GIS Mapping, 2004, “Methane and Methane Buffer Zones,” http://www.meredithassociates.com/pdf/Methane_Zone_Map.pdf

Duncan, J. M., and Bursey, A., 2007, Soil and Rock Modulus Correlations for Geotechnical Engineering, Center for Geotechnical Practice and Research, Virginia Tech.

Federal Emergency Management Agency, 2009, NEHRP Seismic Provisions for New Buildings and Structures, FEMA P‐750.

Federal Emergency Management Agency, 2000, Prestandard and Commentary For the Seismic Rehabilitation of Buildings, FEMA 356.

Idriss, I. M., and Sun, Joseph I (1992), User's manual for SHAKE91: A Computer Program for Conducting Equivalent Linear Seismic Response Analyses of Horizontally Layered Soil Deposits, University of California‐Davis.

Los Angeles, City of, 1996, “Safety Element of the Los Angeles City General Plan,” Department of City Planning, Los Angeles, California.

Los Angeles, County of, 1990, "Technical Appendix to the Safety Element of the Los Angeles County General Plan," Draft Report by Leighton and Associates with Sedway Cooke Associates.




Metro, 2010, “Final Geotechnical and Environmental Report for Advanced Conceptual Engineering, Proposed Westside Subway Extension, Los Angeles, California,” November 15, 2010, Project Number 4953‐09‐0472.

Metro, 2010, “Seismic Design Criteria, Section 5: Structural/Geotechnical,” report dated January 19, 2010.

Metro, 2011, "Preliminary Geotechnical and Environmental Report, Westside Subway Extension, Los Angeles, California, Volumes 1 through 3,” report dated December 21, 2011.

Metro, 2011, "Century City Area Fault Investigation Report, Westside Subway Extension, Los Angeles, California, Volumes 1 and 2,” report dated October 14, 2011.

Metro, 2012, “Seismic Design Criteria, Section 5: Structural/Geotechnical,” report dated October 16, 2012.

Metro, 2012, “Pump Test Report, Wilshire/La Cienega Station, Westside Subway Extension, Los Angeles, California,” report dated April 5, 2012.

Metro, 2013, “Seismic Design Criteria, Section 5: Structural/Geotechnical,” report dated May, 2013.

Metro, 2013, "Environmental Data Report, Westside Subway Extension, Los Angeles, California,” report dated May, 2013 and Amendments.

Metro, 2013, “Geotechnical Data Report, Wilshire/La Brea Station, Westside Subway Extension, Los Angeles, California,” report dated May, 2013 and Amendments.

Metro, 2013, “Geotechnical Data Report, Wilshire/Fairfax Station, Westside Subway Extension, Los Angeles, California,” report dated May, 2013 and Amendments.

Metro, 2013, “Geotechnical Data Report, Wilshire/La Cienega Station, Westside Subway Extension, Los Angeles, California,” report dated May, 2013 and Amendments.

Mononobe, N and Matsuo, H. (1929), On Determination of Earth Pressures during Earthquakes, Proceedings, World Engineering Congress.

Okabe, S (1926), General Theory of Earth Pressures, Journal of Japan Society of Civil Engineering, Vol. 12 (No. 1).

Pacific Earthquake Engineering Research Center (PEER): NGA Strong Motion Database, Website: http://peer.berkeley.edu/peer_ground_motion_database.

Risk Engineering, 2012, EZ‐Frisk 7.62, Software for Earthquake Ground Motion Estimate.

State of California Department of Conservation, Division of Oil, Gas, and Geothermal Resources, 2006, “Oil and Gas Wildcat Well Maps 116, 117, 118, and W1‐5”, June 29, 2006.

U. S. Geological Survey, 2011, “2009 Interactive Deaggregation,” Website: https://geohazards.usgs.gov/deaggint/2008/index.php


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W E S T S I D E S U B W A Y E X T E N S I O N P R O J E C T

TUNNELS – REACHES 1 THROUGH 3

AMEC Environment & Infrastructure, Inc. 6001 Rickenbacker Road Los Angeles, Calfiornia 90040 USA Ph: +1 (323) 889‐5300 Fax +1 (323) 721‐6700 www.amec.com

MEMO

To

Ms. Amanda Elioff, P.E. Parsons Brinckerhoff

Date Amendment 3: Amendment 4: Project No.

May 22, 2013 October 15, 2013 November 19, 2013 4953‐11‐1422

Subject Geotechnical Design Memorandum – Section 1 (Amendment 4)

Tunnel Reaches 1, 2, and 3 of Section 1 (From Existing Wilshire/Western Station to Proposed Wilshire/La Cienega Station) Westside Subway Extension, Los Angeles, California

This technical geotechnical design memorandum (GDMTM) for the tunnel reaches 1 through 3 has been prepared as part of the Advanced Preliminary Engineering (Adv. PE) phase of the Wilshire/Western to Wilshire/La Cienega portion (Section 1) of the proposed Westside Subway Extension project for the Los Angeles County Metropolitan Transportation Authority (Metro).

The results of the Advanced Conceptual Engineering (ACE), Preliminary Engineering (PE) and Adv. PE phase investigations performed for the tunnel reaches were presented in their respective Geotechnical Data Reports (GDRs), dated May 22, 2013. Additional explorations were performed in early 2013 along the Reach 2 tunnel alignment and in August‐September, 2013 along the Reach 1 alignment. The additional data was included in an Amendment #2 of the GDRs dated September 16, 2013 for Reach 2 and in an Amendment #3 of the GDR dated October 15, 2013 for Reach 1. The interpretation of the additional data is included in this Amendment #3 of the TMsThe interpretation of the additional data for Reach 1 and Reach 2 is included in this Amendment #4 of the GDM.

This technical memorandumGDM presents interpretation of the field and laboratory data obtained in the ACE, PE and 2012/2013 Adv. PE phase investigations. This TM GDM presents geotechnical recommendations for tunnel design.

The geotechnical parameters presented in this report reflect the design team’s judgment of anticipated subsurface conditions and ground behavior based on the construction means and methods anticipated. The design data presented herein were established by considering available geologic and geotechnical data, together with past construction experience and anticipated construction methods in similar ground conditions. Development of the project design recommendations required interpretation of the data obtained from various sources, including: geologic maps; hollow stem auger, rotary, and core borings; geophysical surveys; and in‐situ and laboratory tests, as well as the consideration of information from previous construction projects completed in similar geologic conditions. While actual conditions encountered in the field are expected to be within the range of conditions discussed herein, the locations where specific ground and groundwater conditions are encountered may vary from those described in this report. In addition to the specific conditions described herein, the ground behavior will

Section 1, Tunnel Reaches 1 through 3 – Technical Geotechnical Design Memorandum Westside Subway Extension May 22, 2013 October 15, 2013 Amendment 3 November 19, 2013 Amendment 4

also depend on the construction sequence and methods employed, as well as the Contractor’s equipment and workmanship. The project design, therefore, assumes that the construction methods and level of workmanship will be consistent with those that can reasonably be expected from an experienced and qualified contractor.

It is our understanding that this TM GDM is being prepared for inclusion in the Request for Proposal Package being prepared for a Design‐Build Contract for Section 1.

It is a pleasure to be of continuing professional service to you. Please call if you have any questions or if we can be of further assistance.

Sincerely,

AMEC Environment & Infrastructure, Inc.

Hari Ponnaboyina, P.E. Senior Engineer‐Geotechnical

Martin B. Hudson, Ph.D., G.E. Project Manager/Principal Engineer

Perry A. Maljian, G.E. Senior Principal Engineer/ Senior Vice President

Section 1, Tunnel Reaches 1 through 3 – Technical Geotechnical Design Memorandum Westside Subway Extension



Table of Contents

1.0 TUNNEL REACH DESCRIPTIONS ................................................................................................ 1

2.0 GEOTECHNCIAL INPUT FOR TUNNEL DESIGN ............................................................................ 2

3.0 ENGINEERING PROPERTIES OF PRINCIPAL GEOLOGIC UNITS .................................................... 4

4.0 DYNAMIC PROPERTIES OF SOIL AND BEDROCK ...................................................................... 11

5.0 GROUND MOTION STUDY ...................................................................................................... 11

6.0 GEOTECHNICAL INSTRUMENTATION AND MONITORING ....................................................... 13

7.0 LIMITATIONS AND BASIS FOR RECOMMENDATIONS .............................................................. 13

8.0 REFERENCES .......................................................................................................................... 14

List of Tables Table 2‐1: Anticipated Ground Conditions in Reach 1 .................................................................................. 2

Table 2‐2: Anticipated Ground Conditions in Reach 2 .................................................................................. 3

Table 2‐3: Anticipated Ground Conditions in Reach 3 .................................................................................. 3

Table 3‐1: Engineering Properties of Principal Geologic Units (Tunnel Reach 1) ......................................... 7

Table 3‐2: Engineering Properties of Principal Geologic Units (Tunnel Reach 2) ......................................... 8

Table 3‐3: Engineering Properties of Principal Geologic Units (Tunnel Reach 3) ....................................... 10

Table 5‐1: PGA and PGV for ODE and MDE Events ..................................................................................... 12

List of Plates

Plates 1‐1 through 1‐3: Particle Size Distribution of Soils Anticipated in Tunnel Excavation (Reach 1) Plate 1‐4: TBM Clogging Potential of Soils (Reach 1) Plate 1‐5: Seismic Design Parameters (Reach 1) Plates 2‐1 through 2‐4: Particle Size Distribution of Soils Anticipated in Tunnel Excavation (Reach 2) Plate 2‐5: TBM Clogging Potential of Soils (Reach 2) Plate 2‐6: Seismic Design Parameters (Reach 2) Plates 3‐1 through 3‐3: Particle Size Distribution of Soils Anticipated in Tunnel Excavation (Reach 3) Plate 3‐4: TBM Clogging Potential of Soils (Reach 3) Plate 3‐5: Seismic Design Parameters (Reach 3)

Section 1, Tunnel Reaches 1 through 3 – Technical Geotechnical Design Memorandum Westside Subway Extension



SUMMARY OF REVISIONS TO THE MAY 22, 2013AMENDMENT 3 TMGDM

Section/Figure/Table Revisions Page Nos.

Transmittal Added statement about additional explorations performed in 2013 along Reach 1 and Reach 2 tunnel alignment and a reference to Amendment #2 of the Reach 2 GDR and to

Amendment #4 of the Reach 1 GDR

Section 1.0 Revised date of plans from May to October 2013 for tunnel profile

1

Revised tunnel invert depth for Reaches 2 and 3

Table 2‐1 Revised date of plans from May to October 2013 for tunnel profile

2


3


4

Table 3‐1 Updated table with new data and footnotes for explanation of effective and undrained cohesion/friction angles and static

elastic modulus

7

Section 5 Added latest reference for Metro Seismic Design Criteria dated May, 2013

11

Table 5‐1 Updated table with ground motion parameters computed using seismic data from G‐319 and G‐403

13

Revised date of plans from May to October 2013 for tunnel profile

13

Section 8.0 Listed reference for Amendment #2 of the GDR for Reach 2 and Amendment #4 of the GDR for Reach 1

14 to 15

Revised references for GDRs to include Amendments to the May, 2013 submittals

Added latest reference for Metro Seismic Design Criteria dated May, 2013

Plates 1‐1, 1‐2 and 1‐5 Added additional data from borings drilled in 2013

Plates 2‐1 thru 2‐6 Added additional data from borings drilled in 2013Additional data added

Section 1, Tunnel Reaches 1 through 3 – Technical Memorandum Westside Subway Extension



1.0 TUNNEL REACH DESCRIPTIONS

This technical memorandum has been prepared for tunnels within Section 1 of the Westside Subway Extension project, which is about 3.44 miles long and runs beneath Wilshire Boulevard from the existing Wilshire/Western station to about 817 feet west of proposed Wilshire/La Cienega station. The Section 1 lies within two local jurisdictions – the City of Los Angeles, and the City of Beverly Hills. The tunnels follow an east‐west alignment with stations located at the intersections of: Wilshire Boulevard and La Brea Avenue; Wilshire Boulevard and Fairfax Avenue, and; Wilshire Boulevard and La Cienega Boulevard.

The tunnels will have aan interior diameter of 18 feet‐10 inches. For the purpose of this memorandum, the tunnel bore excavated diameter was considered to be about 22 feet. The tunnel alignment considered for this memorandum is based on the plans dated May October 2013 and included in Geotechnical Data Reports (Metro, May 2013) and Amendments.

A reach is defined as the portion of tunnel between any two stations. Section 1 of the project has three tunnel reaches and a tail track tunnel reach. A description of each of the three reaches and the tail track is presented below:

Reach 1 is the portion of the tunnel alignment between existing Wilshire/Western station located at the western terminus of the existing subway (purple line) and the planned Wilshire/La Brea station. This reach is about 1.82 miles long; with the depth to tunnel invert varying from about 55 to 115 feet below ground surface (bgs). A deeper tunnel profile may also be considered. The tunnel invert for this deeper profile may vary from 55 to 145 feet bgs. However, this deeper profile is not the basis for this report.

Reach 2 is the portion of the tunnel alignment between the planned Wilshire/La Brea and Wilshire/Fairfax stations. This reach is about 0.84 miles long; with the depth to tunnel invert varying from 65 70 to 120 bgs.

Reach 3 is the portion of the tunnel alignment between the planned Wilshire/Fairfax station and Wilshire/La Cienega station. This reach is about 0.62 miles long; with the depth to tunnel invert varying from 60 65 to 90 feet bgs.

Tail Track tunnel extends west of the planned Wilshire/La Cienega Station. A separate technical memorandum for the Tail Track reach of the tunnel (dated May 2013) was submitted

In addition, tunnel cross passages that connect eastbound and westbound tunnels are typically spaced at about 800 feet along the tunnel alignment.

To obtain additional subsurface data for the Contractor’s option to deepen tunnel profile in Reach 1 alignment by 10 to 20 feet, additional borings were recently performed in September through October, 2013. Data from the additional borings along Tunnel Reach 1 will be issued in a future amendment to this TM and GDR.

Section 1, Tunnel Reaches 1 through 3 – Technical Memorandum Westside Subway Extension May 22, 2013 October 15, 2013 Amendment 3 November 19, 2013 Amendment 4 Page 2

2.0 GEOTECHNCIAL INPUT FOR TUNNEL DESIGN

Reach 1

Along Reach 1, the tunnel will be excavated in the San Pedro and Fernando Formations and the anticipated ground conditions in the tunnel excavation along different stretches of Reach 1 are presented in Table 2‐1.

Table 2-1: Anticipated Ground Conditions in Reach 1

Approximate Cross-streets* Geologic

Formation

Tunnel Length (miles)

Percent of Tunnel Excavation in

Reach 1 Comments

South Manhattan Pl. to 150 ft west of South Wilton Pl.

San Pedro 0.26 14 Tunnel entirely in San Pedro Formation

150 ft west of South Wilton Pl. to 80 ft west of South Plymouth

Blvd.

Mixed-Face (San Pedro and

Fernando) 0.48 27

The tunnel invert is less than 10 feet into Fernando Formation and the remaining

upper portion of the tunnel is in San Pedro Formation

80 ft west of South Plymouth Blvd. to 300 ft west of Arden

Blvd.


Fernando) 0.21 12

Less than 10 feet of the upper portion of the tunnel is in San Pedro Formation and the

remaining bottom portion of the tunnel is in Fernando Formation

300 ft west of South Arden Blvd. to 180 ft west of South

Tremaine Ave. Fernando 0.53 29 Tunnel entirely in Fernando Formation

180 ft. west of South Tremaine Ave. to 80 ft. west of South

McCadden St.


Fernando) 0.08 4

The San Pedro/Fernando contact cuts the tunnel diagonally along tunnel length

80 ft. west of McCadden St. to South Orange Dr.

San Pedro 0.25 14 Tunnel entirely in San Pedro Formation

* based on plans dated May October 2013, included in GDR.

Based on current groundwater conditions, planned tunnel diameter and tunnel invert depths; the tunnel invert is expected to be under a hydrostatic head of about 40 to 85 feet.

Reach 2

Along Reach 2, the tunnel will be excavated in the San Pedro and Fernando Formations and the anticipated ground conditions in the tunnel excavation along different stretches of Reach 2 are presented in Table 2‐2. A majority (more than 70%) of the tunnel alignment will be excavated through tar‐impacted soils and bedrock.





Approximate Cross-streets* Geologic Formation Tunnel Length (miles)

Percent of Tunnel

Excavation in Reach 2

Comments

250 ft. west of South La Brea Ave. to 60 ft. west of South

Dunsmuir Ave. San Pedro 0.20 24

Tunnel entirely in San Pedro Formation 60 ft. west of South Dunsmuir

Ave. to 100 ft. east of South Burnside Ave.

Tar-Impacted San Pedro 0.03 3

100 ft. east of South Burnside Ave. to 120 ft. east of South

Ridgeley Dr.

Tar-Impacted Mixed-Face (San Pedro and Fernando)

0.06 7

San Pedro/Fernando contact cuts the tunnel diagonally along tunnel

length

120 ft. east of South Ridgeley Dr. to 100 ft. west of South

Stanley Ave. Tar-Impacted Fernando 0.36 43

Tunnel entirely in Fernando Formation

100 ft. west of Stanley Ave. to 300 ft. west of South Stanley

Ave.

Tar-Impacted Mixed-Face (San Pedro and Fernando)

0.04 5

San Pedro/Fernando contact cuts the tunnel diagonally along tunnel

length

300 ft. west of South Stanley Ave. to 80 ft. west of Ogden Dr.

Tar-Impacted San Pedro 0.15 18 Tunnel entirely in San

Pedro Formation

* based on plans dated May October 2013, included in GDR.


Reach 3

Along Reach 3, the tunnel will be excavated entirely in the San Pedro Formation and the anticipated ground conditions in the tunnel excavation along different stretches of Reach 3 are presented in Table 2‐3. A small portion of the tunnel alignment will be excavated through tar‐impacted soils.


Approximate Cross-streets* Geologic Formation Tunnel Length (miles)

Percent of Tunnel

Excavation in Reach 3

Comments

300 ft. west of South Fairfax Ave. to 140 ft. east of South Crescent

Heights Blvd Tar-Impacted San Pedro 0.14 22 Tunnel entirely in

San Pedro Formation 140 ft. east of South Crescent

Heights Blvd. to South Tower Dr. San Pedro 0.48 78

* based on plans dated MayOctober 2013, included in GDR.



3.0 ENGINEERING PROPERTIES OF PRINCIPAL GEOLOGIC UNITS

Engineering properties were compiled in the principal geologic units anticipated in the tunnel excavations and a statistical analysis was performed to estimate the lower bound, upper bound and design values for the properties. The properties were evaluated by sub‐dividing each geologic unit into fine‐grained and coarse‐grained before performing the statistical analysis. The engineering properties of interest for the three reaches are listed below.

SPT Blow Counts

Moisture Content

Dry Density

Bulk Density

Void Ratio

Degree of Saturation

Fines Content

Tar Content

Specific Gravity

Liquid Limit

Plasticity Index

Compression Index

Recompression Index

Expansion/Collapse

At‐rest Lateral Earth Pressure Coefficient (ko)

Unconfined Compression Strength

Effective Cohesion and Friction Angle

Undrained Cohesion and Friction Angle

Elastic Parameters – Young’s Modulus and Poisson’s Ratio

Hydraulic Conductivity

Soil Abrasion Test Value

Corrosion Potential (Minimum Resistivity, pH, Chloride Content, Sulfate Content)




The estimated range (lower bound, upper bound) and design values of the properties listed above for Reaches 1, 2 and 3, are presented in Table 3‐1, Table 3‐2 and Table 3‐3, respectively.

3.1 Particle Size Distribution and Clogging Potential of Materials in Tunnel zone The particle size distribution curves of the tests performed on materials anticipated within the tunnel excavation for Tunnel Reach 1 are presented on Plates 1‐1 through 1‐3. The corresponding curves for materials anticipated within tunnel excavation for Tunnel Reaches 2 and 3 are presented on Plates 2‐1 through 2‐4 and on Plates 3‐1 through 3‐3, respectively.

Using the Atterberg limit tests, an evaluation was made for clogging potential of soils (Thewes and Burger, 2005) anticipated in tunnel excavation for Tunnel Reaches 1 through 3. The results of the clogging potential analysis for Tunnel Reaches 1 through 3 are presented in Plates 1‐4, 2‐5 and 3‐4, respectively.

Based on the evaluation, the materials expected in tunnel excavation for Tunnel Reach 1 are anticipated to have low to high clogging potential. For Tunnel Reach 2, it is noted that a majority of the samples tested were tar‐impacted soils and were heated in a high temperature oven to burn off the tar prior to performing the Atterberg limit tests. Due to the viscous nature of the tar‐impacted soils within Reach 2, a high potential for clogging should be considered. For Tunnel Reach 3, the materials expected in tunnel excavation are anticipated to have medium to high clogging potential.






Table 3-1: Engineering Properties of Principal Geologic Units (Tunnel Reach 1)

Geologic Formations San Pedro Formation (Qsp) Fernando (Tf)

Predominant Grain Size Coarse-Grained Fine-Grained Fine-Grained

USCS Soil Classification SP,SP-SM,SW, SW-

SM,SC,SM,GM MH,ML,CH,CL,CL-ML Siltstone

Engineering Properties Range1 Design Value1 Range1 Design Value1 Range1 Design Value1

SPT Blowcounts "N"-Value2 17 to 100 6265 15 14 to 56 2928 15 to 100 4948

Moisture Content (%) 8 to 48 20 16 to 40 2526 18 to 85 37

Dry Density (pcf) 82 to 123 104 87 to 110 102 55 to 101 85

Total Density (pcf) 106 to 139 126 113 to 130 126 94 to 124 113

Void Ratio 0.34 to 1.02 0.60 0.50 to 0.92 0.620.65 0.64 to 1.79 0.97

Degree of Saturation (%)# 44 to 100 97 82 to 100106 9998 55 to 100111 95

Fines Content (%) 5 to 49 12 53 to 9896 82 66 to 99 96

Specific Gravity 2.52 to 2.76 2.65 2.60 to 2.81 2.71 2.45 to 2.81 2.64

Liquid Limit (%) NP to 45 NP NP to 74 46 NP to 66 51

Plasticity Index (%) NP to 24 NP NP to 49 22 NP to 25 17

Compression Index (Cc) 0.030 to 0.064 0.064 0.054 to 0.140 0.140 0.035 to 0.225 0.225

Recompression Index (Cr) 0.004 to 0.029 0.029 0.010 to 0.034 0.034 0.012 to 0.051 0.051

Collapse Potential (%) 0.00 to 0.12 0.12 0.06 to 0.21** 0.21** 0.01 to 0.16 0.16

Expansion Potential (%) NA NA 0 to 1* 1* 0.03 to 0.21 0.21

At-Rest Lateral Earth Coefficient (k0) 0.52 to 0.90 0.88 0.58 to 0.64* 0.61* 0.40 to 0.59 0.550.53

Unconfined Compressive Strength (psi) NA NA 10 to 100** 50** 24 to 132 77

Effective Cohesion from Direct Shear Test 3 (psf) 0 to 900 300 110 to 1,300 525 300 to 3,800 1,300


26.5 to 38 30.5 16 to 27 26 9 to 32 24


Range = 33 to 39 (Design Value = 34)** NA NA

Effective Cohesion from Triaxial Test 4 (psf) Range = 250 to 750 (Design Value = 350)** NA NA


Range = 28 to 45 (Design Value = 31)** NA NA

Undrained Cohesion from Triaxial Test 4 (psf) Range = 350 to 700 (Design Value = 700)** NA NA

Young’s Modulus from SPT Correlation 5 (ksf) 160 to 938 500 150 to 640 265 110 to 790 340

Young’s Modulus from Triaxial Test 6 (ksf) 3,542** 3,542** 1,890** 1,890** NA NA

Poisson’s Ratio 0.28 to 0.36 0.33 0.35 to 0.42 0.36 0.32 to 0.46 0.37

Hydraulic Conductivity (ft/day) 7 10-3 to 10-3* 50* 10-7 to 10-1* 10-4* 10-8 to 10-3* 10-5*

Soil Abrasion Test Value 23 to 54 34 1 to 20** 10** 2 to 15 45

Corrosivity Results 8:

Minimum Resistivity (Ohm-cm) 420 to 3,560 420 480 to 1,720 480 196 to 680 196

pH 4.2 to 8.2 4.2 3.7 to 8.4 3.7 3.1 to 7.7 3.1

Chloride Content (ppm) 12 to 142 142 15 to 139 139 43 to 2,207 2,207

Sulfate content (ppm) 63 to 5,333 5,333 35 to 3,075 3,075 1,637 to 7,712 7,712

*No test data; reported values are based on data from adjacent reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience ** Limited data; reported values are based on data within this reach and that from adjacent reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience “NP” indicates non-plastic material #Estimated using a specific gravity of 2.65 when a specific gravity test was not performed “NA” indicates engineering property not applicable for the material type pcf = pounds per cubic foot; psf = pounds per square foot; psi = pounds per square inch; cm = centimeter; ppm = parts per million; mg = milligrams; kg = kilograms Notes: 1. Data presented here are based on ACE, PE and Adv. PE phase explorations as well as applicable prior explorations as discussed in Tunnel GDRs 2. Blow counts from environmental hollow-stem-auger borings were not considered 3. Effective cohesion and friction angle are based on yield values from slow direct shear tests. See figure in Appendix E of Wilshire/La Brea GDR on how yield values were picked. 4. Cohesion and friction angle are based on peak shear strength values from Triaxial consolidated-undrained tests. Effective values are based on effective stress and undrained values are based on total stress 5. Based on relationship between elastic modulus and SPT N1,60 from Sabatini et al., (2002, P.148) 6. Based on secant modulus computed at 0.1+0.05% axial strain from Triaxial consolidated-undrained tests 7. Hydraulic conductivity values were based on published data (Department of Water Resources Bulletin 118, California’s Groundwater Update, 2003) 8. For soil corrosivity, the design values correspond to minimum resistivity, lowest pH and highest values for chloride and sulfate content



Geologic Formations San Pedro Formation (Qsp) Tar-Impacted San Pedro Formation (Qsp) Tar-Impacted Fernando (Tf)

Predominant Grain Size Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Fine-Grained USCS Soil Classification SM, SP-SM, SW, SW-SM, SP, GP CL, CL-ML, ML GM, SM, SP, SP-SM, SW-SM CL-ML, ML Siltstone


Range1 Design Value1 Range1 Design Value1



SPT Blowcounts "N"-Value2 12 to 100 78 10 to 70** 25** 16 to 100 67 45 to 53 50 20 to 62 42 Moisture Content (%) 14 to 35 19 19 to 26 25 1 to 24 5 10 to 34 21 10 to 41 22 Dry Density (pcf) 90 to 107 104 99 to 112 106** 90 to 129 112 91 to 104 98** 74 to 98 88 Total Density (pcf) 116 to 130 127 124 to 134 129 96 to 134 119 111 to 114 112 96 to 116 108 Void Ratio 0.55 to 0.84 0.61 0.50 to 0.67** 0.59** 0.28 to 0.84 0.48 0.59 to 0.90** 0.74** 0.69 to 1.23 0.88 Degree of Saturation (%)# 91 to 100 100 100 100 11 to 60 23 45 to 66 56 51 to 88 68 Fines Content (%) 9 to 41 13 60 to 76 68 2 to 41 10 54 to 94 77 36 to 98 79 Tar Content (%) NA NA NA NA 2.0 to 19.4 16.2 16.5 to 19.7 19.0 12 to 29.5 18.7 Specific Gravity 2.65 to 2.68 2.68 2.66 to 2.70 2.68 2.64 to 2.68 2.66 2.66 to 2.86** 2.68** 2.65 to 2.76 2.70 Liquid Limit (%) NA NA NP to 50** 30** NP NP NP NP NP to 55 NP Plasticity Index (%) NA NA NP to 30** 15** NP NP NP NP NP to 18 NP Compression Index (Cc) 0.03 to 0.06** 0.045** 0.04 to 0.15** 0.10** 0.031 to 0.080 0.061 0.100 to 0.116 0.108 0.072 to 0.195 0.117 Recompression Index (Cr) 0.004 to 0.03** 0.017** 0.005 to 0.035** 0.02** 0.002 to 0.010 0.005 0.0107 to 0.015 0.013 0.019 to 0.037 0.024 Collapse Potential (%) 0.01 to 0.04 0.03** 0 to 0.25** 0.15** 0 to 0.30** 0.15** 0.06 to 0.30** 0.15** 0.00 to 0.06 0.02 Expansion Potential (%) NA NA 0 to 1.0* 0.5* 0 to 1.0* 1.0* 0 to 1.0* 1.0* 0 to 0.5** 0.25** At-Rest Lateral Earth Coefficient (k0) 0.38 to 0.59** 0.53** 0.58 to 0.64* 0.61* 0.36 to 0.69 0.65 0.5 to 0.6* 0.55* 0.4 to 0.6* 0.4* Unconfined Compressive Strength (psi) NA NA 10 to 100* 50* NA* NA* 50 to 100* 75* 25.9 to 71.7 46.5

Effective Cohesion from Direct Shear Test 3 (psf) 100 to 700** 300** 650 to 1,300** 975** 0 to 1,300 375 500 to 1,450** 975** 1,400 to 2,450** 1,900**


24 to 31** 26** 21 to 25** 23** 21 to 36 26 28 to 30** 29** 10 to 25.5** 19**

Effective Friction Angle from Triaxial Test 4 (degrees) Range = 22 to 47 (Design Value = 36) 28** 28**

Effective Cohesion from Triaxial Test 4 (psf) Range = 0 to 3,200 (Design Value = 700) 3200** 3200**


Range = 17 to 49 (Design Value = 39) 34** 34**

Undrained Cohesion from Triaxial Test 4 (psf) Range = 100 to 2,000 (Design Value = 375) 500** 500**

Young’s Modulus from SPT Correlation 5(ksf) 197 to 1,677 784 694** 694** 190 to 1,690 1,058 187 to 544 403 281 to 475 345

Young’s Modulus from Triaxial Test 6 (ksf) 4,929** 4,929** NA NA 2,373 to 4,038 2,664 1,378** 1,378** 2,440** 2,440**

Poisson’s Ratio 0.32 to 0.37 0.36 0.37 to 0.39 0.38 0.35 to 0.39 0.37 0.33 to 0.35 0.34 0.36 to 0.45 0.40 Hydraulic Conductivity (ft/day) 7 10-2 to 10-3* 50* 10-7 to 10-1* 10-5* 10-1 to 10-3* 10-2* 10-3 to 10-7* 10-5* 10-8 to 10-3* 10-5* Soil Abrasion Test Value 15 to 35 29 1 to 12* 3* 23 to 35 27 1 to 12* 3* 2.0 to 6.5 6 Corrosivity Results8: Minimum Resistivity (Ohm-cm) 390 to 3,600* 390* 480 to 1,720** 480** 2000 to 220,000 2,000 520 to 2240 520 220 to 1,760 220 pH 2 to 8.2* 2* 3.7 to 8.4** 3.7** 3.5 to 7.9 3.5 3.9 to 7.4 3.9 5.4 to 7.6 5.4 Chloride Content (ppm) 6 to 142* 142* 4 to 139** 139** 4 to 100 100 942 to 1,274 1,274 1,364 to 2,776 2,776 Sulfate content (ppm) 63 to 8,074* 8,074* 35 to 3,075** 3,075** 7 to 101 101 2,149 to 7,151 7,151 1,960 to 5,897 5,897




Geologic Formations San Pedro Formation (Qsp) Tar-Impacted San Pedro Formation (Qsp) Tar-Impacted Fernando (Tf) Predominant Grain Size Coarse-Grained Fine-Grained Coarse-Grained Fine-Grained Fine-Grained USCS Soil Classification SM, SP-SM, SW, SW-SM, SP, GP CL, CL-ML, ML GM, SM, SP, SP-SM, SW-SM CL-ML, ML Siltstone

*No test data; reported values are based on data from adjacent reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience ** Limited data; reported values are based on data within this reach and that from adjacent reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience “NP” indicates non-plastic material #Estimated using a specific gravity of 2.65 when a specific gravity test was not performed “NA” indicates engineering property not applicable for the material type pcf = pounds per cubic foot; psf = pounds per square foot; psi = pounds per square inch; cm = centimeter; ppm = parts per million; mg = milligrams; kg = kilograms Notes: 1. Data presented here are based on ACE, PE and Adv. PE phase explorations as well as applicable prior explorations as discussed in Tunnel GDRs 2. Blow counts from environmental hollow-stem-auger borings were not considered 3. Effective cohesion and friction angle are based on yield values from slow direct shear tests. See figure in Appendix E of Wilshire/La Brea GDR on how yield values were picked. 4. Cohesion and friction angle are based on peak shear strength values from Triaxial consolidated-undrained tests. Effective values are based on effective stress and undrained values are based on total stress 5. Based on relationship between elastic modulus and SPT N1,60 from Sabatini et al., (2002, P.148) 6. Based on secant modulus computed at 0.1+0.05% axial strain from Triaxial consolidated-undrained tests 7. Hydraulic conductivity values were based on published data (Department of Water Resources Bulletin 118, California’s Groundwater Update, 2003) 8. For soil corrosivity, the design values correspond to minimum resistivity, lowest pH and highest values for chloride and sulfate content



Geologic Formations San Pedro Formation (Qsp) Tar-Impacted San Pedro Formation (Qsp)


USCS Soil Classification SM, SC, SP, SP-SM, SW-SM, SC-

SM ML, MH, CL, CL-ML SM, SC, SP, SP-SM, SW-SM, GM CL, MH, ML, CL-ML


Range1 Design 1Value



SPT Blowcounts "N"-Value2 16 to 100 53 10 to 68 23 42 to 100 87 40 to 50* 50*

Moisture Content (%) 2 to 45 14 13 to 44 23 4 to 32 6 10 to 35* 20*

Dry Density (pcf) 83 to 124 106 78 to 119 104 95 to 117 108 90 to 105* 100*

Total Density (pcf) 101 to 136 120 112 to 135 126 115 to 129 122 NA* NA*

Void Ratio 0.33 to 1.00 0.57 0.39 to 1.18 0.60 0.41 to 0.76 0.59 0.6 to 1* 0.75*

Degree of Saturation (%) # 10 to 100 57 83 to 100 99 35 to 91 58 45 to 65* 55*

Fines Content (%) 5 to 50 15 52 to 99 55 9 to 32 12 50 to 95* 75*

Tar Content (%) NA NA NA NA 7 to 19 13 15 to 20* 20*

Specific Gravity 2.62 to 2.71 2.65 2.59 to 2.79 2.73 2.66 to 2.86 2.68 2.65 to 2.76* 2.70*

Liquid Limit (%) 35 to 49 42 NP to 80 44 NP* NP* NP* NP*

Plasticity Index (%) 20 to 27 23 NP to 34 17 NP* NP* NP* NP*

Compression Index (Cc) 0.0433 to 0.0548 0.0476 0.043 to 0.110 0.096 0.067 to 0.116 0.068 0.10 to 0.20* 0.15*

Recompression Index (Cr) 0.0064 to 0.0120 0.0119 0.007 to 0.033 0.031 0.010 to 0.014 0.013 0.02 to 0.04* 0.03*

Collapse Potential (%) 0.02 to 0.23 0.07 0.02 to 0.24 0.13 0.07 to 0.13 0.10 0 to 0.15* 0.10*

Expansion Potential (%) NA NA 0 to 1.0** 0.5** NA NA 0 to 0.5* 0.25*

At-Rest Lateral Earth Coefficient (k0) 0.41 to 0.56* 0.49* 0.62 to 0.79 0.70 0.36 to 0.72 0.67 0.50 to 0.60* 0.55*

Unconfined Compressive Strength (psi) NA NA 10 to 100* 50* NA NA 50 to 100* 75* Effective Cohesion from Direct Shear Test3 (psf)

0 to 1250 600 450 to 1750 1150 500 to 950 725** 500 to 1,500* 1,000*

Effective Friction Angle from Direct Shear3 Test (degrees)

26 to 36 29 17 to 24 21 17 to 30** 24** 28 to 30* 29*




Range = 0 to 3,000 (Design Value = 600)




Range = 100 to 1,200 (Design Value = 300)

Soil Abrasion Test Value 6 to 24 9 1 to 12* 3* 22 to 35 28 1 to 12* 3*


0 to 1,210 553 0 to 393 198 691 to 13,780 8,686 150 to 900 320


NA NA 1,013 to 3,057** 2,200** 1,257 to 8,833 3,374 1,867** 1,867**

Poisson’s Ratio 0.29 to 0.36 0.34 0.37 to 0.41 0.39 0.33 to 0.41 0.37 0.36 to 0.45 0.4

Hydraulic Conductivity (ft/day) 7 10-2 to 50* 5* 10-7 to 10-1* 10-5* 10-3 to 10-1* 10-2* 10-7 to 10-3* 10-5*

Corrosivity Results8:

Minimum Resistivity (Ohm-cm) 392 to 1,480 392 640 to 1080 640 1,200 to 26,400 1,200 220 to 1,760* 220*

pH 2 to 8 2 8 8 3 to 8 3 5.4 to 7.6* 5.4*

Chloride Content (ppm) 6 to 15 15 4 to 26 26 3 to 7 7 1364 to 2,776* 2,776*

Sulfate content (ppm) 249 to 8074 8074 173 to 702 702 81 to 1183 1183 1,960 to 5,897* 5,897*

*No test data; reported values are based on data from adjacent reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience ** Limited data; reported values are based on data within this reach and that from adjacent reaches/correlation with other soil and bedrock properties/published data in literature, and/or based on our prior experience “NP” indicates non-plastic material #Estimated using a specific gravity of 2.65 when a specific gravity test was not performed “NA” indicates engineering property not applicable for the material type Notes: 1. Data presented here are based on ACE, PE and Adv. PE phase explorations as well as applicable prior explorations as discussed in Tunnel GDRs 2. Blow counts from environmental hollow-stem-auger borings were not considered 3. Effective cohesion and friction angle are based on yield values from slow direct shear tests. See figure in Appendix E of Wilshire/La Brea GDR on how yield values were picked. 4. Cohesion and friction angle are based on peak shear strength values from Triaxial consolidated-undrained tests. Effective values are based on effective stress and undrained values are based on total stress 5. Based on relationship between elastic modulus and SPT N1,60 from Sabatini et al., (2002, P.148) 6. Based on secant modulus computed at 0.1+0.05% axial strain from Triaxial consolidated-undrained tests 7. Hydraulic conductivity values were based on published data (Department of Water Resources Bulletin 118, California’s Groundwater Update, 2003) 8. For soil corrosivity, the design values correspond to minimum resistivity, lowest pH and highest values for chloride and sulfate content




4.0 DYNAMIC PROPERTIES OF SOIL AND BEDROCK

Dynamic properties of soils and bedrock formations anticipated in the tunnel zone were evaluated using the shear‐wave data from seismic cone penetration tests (CPTs) and borings with suspension logging testing. The small strain elastic modulus (Es) and shear modulus (Gs) were estimated from the small strain shear‐wave velocity of these materials (Cs).

For the ODE and MDE events, small‐strain shear wave velocity was degraded using the guidelines provided in Table 19.2‐1 of FEMA P‐ 750 (2009). The computed shear‐wave velocity, elastic modulus (Es) and shear modulus (Gs) for small‐strain for ODE and MDE events are shown on Plates 1‐6, 2‐6 and 3‐5 for Reaches 1, 2 and 3, respectively.

5.0 GROUND MOTION STUDY

Ground motion parameters were estimated for seismic design of the tunnel using the available small‐strain shear wave velocity measurements from the CPTs and borings. Peak ground acceleration (PGA) and peak ground velocity (PGV) were estimated in accordance with Section 2.3.1 of the Metro Rail Seismic Design Criteria [(Metro Seismic Design Criteria), Metro (May, 2013)]. Two hazard levels were evaluated as listed below, assuming a design life of 100 years for the subway per the Metro Design Criteria.

Operating Design Earthquake (ODE) – defined as an earthquake event likely to occur once in the design life, where structures are designed to respond without significant structural damage. The current Metro Seismic Design Criteria defines ODE as an event with 50% probability of exceedence in 100 years (corresponding to a return period of 150 years).

Maximum Design Earthquake (MDE) – defined as an earthquake event with a low probability of occurring in the design life, where structures are designed to respond with repairable damage and to maintain life safety. The current Metro Seismic Design Criteria defines MDE as an event with 4% probability of exceedence in 100 years (corresponding to a return period of 2,475 years)

The PGA for the ODE and MDE events were estimated using the 2009 USGS Interactive Probabilistic Seismic Hazard Analysis (PSHA) Deaggregation tool on the USGS website (USGS, 2011). The USGS deaggregation tool uses the Next Generation Attenuation (NGA) relationships of Boore‐Atkinson (2008), Campbell‐Bozorgnia (2008) and Chiou‐Youngs (2008) for the ground motion prediction equations. Based on the available combinations of exceedence probability and exposure time, ground motions for the MDE event were computed for a probability of exceedence of 2% in 50 years (equivalent to the 4% in 100 year) criteria stated in Metro Seismic Design Criteria.

The PGV was computed using the relationship between PGV‐S1 presented in the FHWA‐NHI‐10‐034 manual (2009). The degradation of shear wave velocity with strain level (for ODE and MDE) was obtained from Table 19.2‐1 of FEMA P‐ 750 (2009). The shear wave velocity adjusted for strain level was then used in the USGS Deaggregation tool to compute the respective PGA and PGV in the manner stated above.


The small strain shear wave velocity, PGA and PGV and those for ODE and MDE levels at tunnel elevation are presented in Plates 1‐6, 2‐6 and 3‐5 for Reaches 1, 2 and 3, respectively. In summary, the PGA and PGV estimated at each discrete CPT and boring location are presented in Table 5‐1.

Table 5-1: PGA and PGV for ODE and MDE Events

Reaches CPT No. Small-strain shear-

wave Velocity (ft/sec)*

Peak Ground Acceleration (PGA), in g Peak Ground Velocity (PGV), ft/sec

ODE MDE ODE MDE

Reach 1 C-101 995 0.30 0.85 1.52 5.06

C-105 1270 0.29 0.86 1.34 4.64

C-106 1330 0.29 0.86 1.28 4.49

C-107 1340 0.28 0.85 1.27 4.52

C-108 1435 0.28 0.85 1.19 4.15

C-109A 980 0.30 0.82 1.51 4.97

C-110(1) 1430 0.29 0.86 1.21 4.21

G-304 1240 0.29 0.86 1.34 4.63

G-305 1190 0.30 0.84 1.48 4.97

G-403 1170 0.29 0.85 1.38 4.73

Reach 2 CB-103 1130 0.29 0.84 1.40 4.80

CB-104(2) 1370 0.28 0.85 1.24 4.36

G-312(2) 1245 0.29 0.84 1.32 4.63

G-319(2) 1125 0.29 0.84 1.40 4.82

Reach 3 C-302(3) 935 0.30 0.82 1.55 5.22

C-112(3) 1000 0.30 0.84 1.49 5.19

Design Values for Section 1 0.30 0.86 1.55 5.22

(1)CPT performed at Wilshire/La Brea station (2) CPT/boring performed at Wilshire/Fairfax station (3) CPT performed at Wilshire/La Cienega station

* based on plans dated October 2013, included in GDR.




6.0 GEOTECHNICAL INSTRUMENTATION AND MONITORING

A geotechnical instrumentation and monitoring program should be planned and implemented to monitor ground movements and any potential distress during tunnel excavation in the adjacent buildings, other structures and critical utilities. The following instrumentation should be considered.

Ground surface settlement points

Building settlement reference points

Inclinometer casings

Extensometers

Observation wells (water and subsurface gas)

Tiltmeters and crackmeters on sensitive buildings or structures

Construction vibration monitoring near sensitive buildings or structures

Photo documentation of the baseline/ preconstruction survey in existing buildings

Depending on the features of the adjacent structures (age of the building, construction type, sensitivity of the structures to noise and vibration), a more detailed and site‐specific instrumentation and monitoring program may need to be developed.

7.0 LIMITATIONS AND BASIS FOR RECOMMENDATIONS

The professional services have been performed using the degree of care and skill ordinarily exercised, under similar circumstances, by reputable geotechnical consultants practicing in this or similar localities. No other warranty, expressed or implied, is made as to the professional advice included in this technical memorandum. This memorandum has been prepared for the Los Angeles County Metropolitan Transportation Authority (Metro) and its design consultants to be used solely for the evaluation for the Reaches in Section 1 planned as part of the proposed Westside Subway Extension project. The memorandum has not been prepared for use by other parties, and may not contain sufficient information for purpose of other parties or other uses.

In developing this memorandum, AMEC (PB team member) relied on subsurface information obtained during 2012/2013 Adv. PE phase and by its predecessor company MACTEC in the AA, ACE, and PE phase studies and its other predecessor companies, Law/Crandall and LeRoy Crandall and Associates, as well as subsurface information obtained by other firms. Subsurface conditions are, by their nature, uncertain and may vary from those encountered at the locations where visual inspections, borings, surveys, or other explorations were made.


8.0 REFERENCES

Abrahamson, N.A., and Silva, W.J., 2008, Summary of the Abrahamson & Silva NGA Ground Motion Relations, Earthquake Spectra, Volume. 24, No. 1, pp. 67‐97.

Boore, D.M., and Atkinson, G.M., 2008, Ground‐Motion Prediction Equations for the Average Horizontal Component of PGA, PGV, and 5%‐Damped PSA at Spectral Periods Between 0.01 s and 10.0 s, Earthquake Spectra, Volume 24, No.1, p. 99‐138.

Campbell, K.W., and Bozorgnia, Y., 2008, Ground Motion Model for the Geometric Mean Horizontal Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response Spectra for Periods Ranging from 0.01s to 10.0 s, Earthquake Spectra, Volume 24, No.1, pp. 139‐171.

Chiou, B.S.J., and Youngs, R.R., 2008, An NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra, Earthquake Spectra, Volume 24, No.1, pp. 173‐215.

Duncan, J. M., and Bursey, A., 2007, Soil and Rock Modulus Correlations for Geotechnical Engineering, Center for Geotechnical Practice and Research, Virginia Tech.

Federal Emergency Management Agency, 2009, NEHRP Seismic Provisions for New Buildings and Structures, FEMA P‐750.

Federal Emergency Management Agency, 2000, Prestandard and Commentary For the Seismic Rehabilitation of Buildings, FEMA 356.

Metro, 2010, “Final Geotechnical and Environmental Report for Advanced Conceptual Engineering, Proposed Westside Subway Extension, Los Angeles, California,” November 15, 2010, Project Number 4953‐09‐0472.

Metro, 2010, Seismic Design Criteria, Section 5: Structural/Geotechnical, report dated January 19, 2010.

Metro, 2011, "Preliminary Geotechnical and Environmental Report, Westside Subway Extension, Los Angeles, California, Volumes 1 through 3,” report dated December 21, 2011.

Metro, 2011, "Century City Area Fault Investigation Report, Westside Subway Extension, Los Angeles, California, Volumes 1 and 2,” report dated October 14, 2011.

Metro, 2012, “Seismic Design Criteria, Section 5: Structural/Geotechnical,” report dated October 16, 2012.

Metro, 2013, “Seismic Design Criteria, Section 5: Structural/Geotechnical,” report dated May, 2013.

Metro 2013, “Geotechnical Data Report, Reach 1, Westside Subway Extension, Los Angeles, California,” report dated May, 2013 and Amendments.






Metro, 2013, “Geotechnical Data Report for Trail Tracks, Westside Subway Extension, Los Angeles, California,” report dated May, 2013 and Amendments.

Metro, 2013, “Technical Memorandum for Trail Tracks, Westside Subway Extension, Los Angeles, California,” report dated January 29, 2013May, 2013 and Amendments.

Metro, 2013, "Environmental Data Report, Westside Subway Extension, Los Angeles, California,” report dated May, 2013 and Amendments.

Thewes, M., and Burger. B., 2004, Clogging of TBM drives in Cay, Tunnels and Tunneling International, June 2004, pp. 28‐31.

U. S. Geological Survey, 2011, “2008 Interactive Deaggregation,” Website: https://geohazards.usgs.gov/deaggint/2008/index.php






PLATES

Plates 1‐1 through 1‐3: Particle Size Distribution of Soils Anticipated in Tunnel Excavation (Reach 1) Plate 1‐4: TBM Clogging Potential of Soils (Reach 1) Plate 1‐5: Seismic Design Parameters (Reach 1) Plates 2‐1 through 2‐4: Particle Size Distribution of Soils Anticipated in Tunnel Excavation (Reach 2) Plate 2‐5: TBM Clogging Potential of Soils (Reach 2) Plate 2‐6: Seismic Design Parameters (Reach 2) Plates 3‐1 through 3‐3: Particle Size Distribution of Soils Anticipated in Tunnel Excavation (Reach 3) Plate 3‐4: TBM Clogging Potential of Soils (Reach 3) Plate 3‐5: Seismic Design Parameters (Reach 3)

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PARTICLE SIZE DISTRIBUTION

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REACH 1

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REACH 1 - San Pedro Formation

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SANDSILT OR CLAY

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REACH 2

Project No.: 4953-11-1423MTA Westside Subway ExtensionLos Angeles, California

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402043/8

REACH 2 - San Pedro Formation


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402043/8

REACH 2 - San Pedro Formation (Tar-Impacted)


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402043/8

REACH 2 - Fernando Formation (Tar-Impacted)


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TBM Clogging Potential of soilsProject No.: 4953-11-1423

Plate 2-5

Prepared/Date: JF 9/17/2013Checked/Date: WL 9/18/2013

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7.00CONSISTENCY INDEX, Ic = (LL-Wc)/PI

20.0 40.0 60.010.0 30.0 50.0

PLASTICITY INDEX, PINote:

1. Atterberg Limits could not be performed on samples with tar. Due to viscous tar in the soil and bedrock samplesconsider these soils to have high potential for clogging.

2. Outside the tar-impacted zone (see plate 1), 1 sample within the tunnel zone was tested and it was non-plastic3. Within the tar-impacted zone (see plate 1), 20 of 23 samples within the tunnel zone were non-plastic

High potential for clogging

Medium potential for clogging

Low potential for clogging

REACH 2

Reference: Clogging of TBM drives in clay, M. Thewes and W. Burger, 2005

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Geotechnical Contract Design No. PS Memoranda 4350 2000

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