Foundation Report Proposed Tieback Retaining Wall Abutment 1 - Sr67 Prospect Avenue Oc Bridge No

FOUNDATION REPORT PROPOSED TIEBACK RETAINING WALL ABUTMENT 1 - SR67 PROSPECT AVENUE OC BRIDGE NO. 57-461, 11-SD-67 SAN DIEGO COUNTY, CALIFORNIA

Prepared for

PARSONS BRINCKERHOFF QUADE & DOUGLAS 707 Broadway, Suite 1700 San Diego, California 92101

Prepared by

GROUP DELTA CONSULTANTS, INC. 92 Argonaut, Suite 120 Aliso Viejo, CA 92656 Tel. (949) 609-1020 Fax (949) 609-1030

GDC Project No. I-391 February 9, 2006

February 9, 2006

PARSONS BRINCKERHOFF QUADE & DOUGLAS 707 Broadway, Suite 1700 San Diego, California 92101

Attention: Mr. Michael Palacios, P.E. Project Manager

Subject: Foundation Report Proposed Tieback Retaining Wall Abutment 1 – SR67 Prospect Avenue OC Bridge No. 57-461, 11-SD-67 San Diego County, California Group Delta Project No. I-391

Dear Michael:

Transmitted with this letter are 3 hard copies and an electronic copy on CD of our geotechnical report for the subject project. The work was performed in general accordance with our proposal dated December 23, 2005 and your authorization. We appreciate the opportunity to provide our services on this project. Should you have any questions, please give us a call at (949) 609-1020.

Sincerely, GROUP DELTA CONSULTANTS, INC.

Kul Bhushan, Ph. D., G.E.. Curt Scheyhing, P.E. President Senior Engineer

Distribution: Addressee (e-mail + 3 hard copies + 1 .pdf file on CD)

TABLE OF CONTENTS Page 1.0 INTRODUCTION 1 1.1 General 1 1.2 Scope of Work 1 1.3 Project Description 2 2.0 GEOTECHNICAL INVESTIGATION 3 2.1 Site Reconnaissance 3 2.2 Review of Existing Information 3 3.0 SITE AND SUBSURFACE CONDITIONS 4 3.1 Site Conditions 4 3.2 Site Geology 4 3.3 Geologic Profiles and Engineering Parameters 4 3.3.1 Lithology 4 3.3.1.1 Layer 1: Dense to Very Dense Silty Gravelly Sand 4 3.3.1.2 Layer 2: Highly Weathered Granitic Bedrock 5 3.3.2 Geologic Structure 5 3.3.3 Natural Slope Stability 5 3.3.4 Surface Water 6 3.3.5 Groundwater 6 3.3.6 Engineering Properties 6 4.0 ANALYSIS AND RECOMMENDATIONS 8 4.1 Seismic Study 8 4.1.1 Regional Seismicity 8 4.1.2 Ground Motion 8 4.1.3 Ground Surface Rupture and Displacement Due to Faulting 9 4.1.4 Seismic Compaction 9 4.2 Liquefaction Evaluation 9 4.3 Corrosion Evaluation 9 4.4 Scour Evaluation 10 4.5 Foundation Recommendations 10 4.5.1 General 10 4.5.2 Grout-Soil Bond Stress in Bonded Zone 10 4.5.3 Earth Pressures 11 4.5.4 Wall Stability Check by Limit Equilibrium Methods 12 4.5.5 Wall Drainage 12 4.5.5.1 Surface Drainage 12 4.5.5.2 Wall Drainage 12 4.5.6 Vertical Component of Tieback Load (Friction and Bearing) 12 4.5.7 Load Testing 13 4.6 Slope Stability 13 4.6.1 General 13

4.6.2 Factor of Safety 13 4.6.3 Global Stability of Tieback Wall and Permanent Slope 13 4.6.3.1 Static Analysis 13 4.6.3.2 Pseudo-Static Analysis 14 4.6.4 Stability of Temporary Excavations 14 4.7 Construction Considerations 15 4.7.1 Construction Advisories 15 4.7.2 Excavation 15 4.7.3 Buried Utilities 16 4.7.4 Remnants of Previous Construction 16 4.7.5 Hazardous Waste Considerations 16 4.7.6 Differing Site Conditions 16 5.0 REFERENCES 17 6.0 LIMITATIONS 19

LIST OF FIGURES

Figure 1a Vicinity Map Figure 1b Location Map Figure 2 (a, b) General Plans (Original and Widen) Figure 3 (a, b) Foundation Plans (Original and Widen) Figure 4 (a, b) Abutment Details (Original and Widen) Figure 5 Tieback Wall Typical Design Section Figure 6 As-Built Log of Test Borings Figure 7 Caltrans Fault and PBA Map Figure 8 (a, b) Earth Pressure Diagrams for Static and Seismic Loading Figure 9 Static Stability Results for Permanent Wall Figure 10 Pseudo-Static Stability Results for Permanent Wall Figure 11 (a, b) Stability Results for Temporary Excavations

LIST OF APPENDICES

Appendix A Site Photographs Appendix B Analyses and Calculations

N:\Projects\_AV\I300\I-391 Tieback Wall - Prospect Ave. OC\Report\I-391 FR SR67 Prospect Ave OC Tieback Wall.doc

FOUNDATION REPORT PROPOSED TIEBACK RETAINING WALL ABUTMENT 1 – SR67 PROSPECT AVENUE OC BRIDGE NO. 57-461, 11-SD-67 SAN DIEGO COUNTY, CALIFORNIA

1.0 INTRODUCTION

1.1 General

The proposed project involves widening of the southbound SR67 below Abutment 1 of the existing Overcrossing structure. The site vicinity and location map are shown in Figures 1a and 1b.

The widening involves making a temporary vertical excavation into the abutment slope and installing a shotcrete retaining wall restrained by tieback ground anchors. This report provides geotechnical recommendations for the design of the retaining structure.

1.2 Scope of Work

Our scope of work for this study included:

• Reviewing existing data including Caltrans Seismic Hazard Map (1996) and as-built plans and Log of Test Borings (LOTBs) for the existing structure; • Performing a site visit, reconnaissance, and photographic documentation of the project site; • Coordinating with structure designers at Parsons Brinckerhoff (PB); • Performing geotechnical analyses based on existing available data to develop geotechnical recommendations for project design; • Summarizing relevant data and presentation of specific recommendations for design of the tieback retaining wall in this Foundation Report.

Our scope of work utilizes existing data, and does not include any subsurface investigation or laboratory testing.

The design and construction of the project will be performed in accordance with current Caltrans design practice, and Standard Plans and Specifications. This report is prepared in general accordance with “Caltrans Guidelines for Foundation Investigation and Reports, Version 1.2 (dated June, 2002).”

1.3 Project Description

The existing Overcrossing (Bridge No. 57-461) is a 2-span bridge where Prospect Avenue crosses over State Route 67 Freeway (Figures 1a and 1b). It was originally designed / constructed in 1962 and was later widened in 1978-1979. State Route 67 is in a cut area below the original grades. Cut slopes are inclined at 2H: 1V with heights of about 25 to 30 feet (7.6 to 9.1 m). An estimated 3 to 5 feet (1 to 1.5 m) of approach fill was placed at the abutments.

The original spans are reinforced concrete box girders with a girder depth of 6.5 feet (2.0 m), and the widening is a Cast-in-Place Pre-Stressed Concrete Box Girder with a girder depth of 4.25 feet (1.3 m). Abutments are diaphragm-type supported on continuous footings embedded in the slope with widths of 2.5 feet or 0.76 m (original) to 4 feet or 1.2 m (widening). Bent 2 has two single columns supported on spread footings. Allowable foundation bearing pressure is 4 tsf (385 kPa) at Abutments 1 & 3, and 6 tsf (575 kPa) at Bent 2.

The as-built General Plans for the original construction and the widening are presented in Figures 2a and 2b, as-built Foundation Plans for the original construction and the widening are presented in Figures 3a and 3b, and as-built Abutment Details for the original construction and the widening are presented in Figures 4a and 4b, respectively.

It is anticipated that the tieback wall will have a height of 10 feet (3 m) or less, and that the construction backcut will be 10 feet (3 m) or more from the edge of the abutment footing. The wall will be excavated and constructed in lifts, and there will be two levels of tiebacks. A typical design section is illustrated in Figure 5.

2.0 GEOTECHNICAL INVESTIGATION

Our scope of work was to develop geotechnical recommendations for the proposed wall based on a site visit, surface reconnaissance, and review of available published data and as-built information provided by PB. Drilling, sampling, and laboratory testing were not within the current scope of work.

2.1 Site Reconnaissance

A surface reconnaissance was performed by our engineer on January 18, 2006. This included walking the site, observing the surface conditions and exposed soils and slopes, performing manual probing of the surficial soils with a steel probe to estimate relative density of the surface materials, and taking detailed photographs of the project site. The photographs are included in Appendix A.

2.2 Review of Existing Information

The relevant dimensions of the structure, foundations, and graded slopes, and the location of the original grades at the site, were determined based on review of the as-built plans (see Figures 2a through 4b). Subsurface conditions were evaluated based on our local knowledge of the area geology, and review of available subsurface data presented on the as-built Log of Test Borings (LOTBs) in Figure 6.

3.0 SITE AND SUBSURFACE CONDITIONS

3.1 Site Conditions

Original grades in the area of the Overcrossing ranged from El. 431 feet (131.4 m) at Abutment 1 to El. 438 feet (133.5 m) at Abutment 3. The SR67 roadway below the bridge was constructed by excavation to between El. 412 and El. 414 feet (125.6 to 126.2m). Thin approach fills (2 to 6 feet or 0.6 to 1.8 m) were placed at the abutments to raise the grades along Prospect Avenue to about El. 433 feet (132.0 m) at Abutment 1 to El. 444 feet (135.3 m) at Abutment 2. Abutment slopes are graded at 2H: 1V inclination. Prospect Avenue drops in elevation at about 5% gradient from east to west. SR67 is nearly level at the Overcrossing location, and rises at a slight gradient to the north. Natural drainage at the bridge site is about 5 to 6% to the southwest. Runoff is generally by sheet flow to storm drains. Granitic rock outcroppings rising to elevations of up to 1000 feet (305 m) are present east of the site, and a small granitic outcropping rising to El. 540 feet (165 m) is present northwest of the site (refer to Figure 1b).

3.2 Site Geology

The site is located in the Peninsular Ranges Geomorphic Province of Southern California. As indicated by the adjacent outcrops, the site is underlain by granitic rock of the Southern California Batholith. The bedrock at the site is highly weathered, and is overlain by a relatively thin mantle of dense soils that may be old fan deposits or decomposed granitic rock.

3.3 Geologic Profiles and Engineering Parameters

3.3.1 Lithology

The as-built LOTB is shown in Figure 6. The original investigation consisted of two 3-inch (76 mm) rotary borings, and 3 penetration borings. The data indicate that the soil/rock profile consists of two generalized layers:

3.3.1.1 Layer 1: Dense to Very Dense Silty Gravelly Sand

The upper 15 feet (+/-) of the profile is composed of soil material described on the LOTB as “dense to very dense silty gravelly sand to sandy gravelly silt.” These materials may be old overconsolidated fan deposits originating in the granitic slopes to the east, and/or decomposed granitic rock that has weathered in place.

All 3 penetration borings, which are dynamic cone penetration tests conducted by driving a steel rod with conical tip into the ground with a drop hammer, reached refusal in very dense materials at depths of 5 feet or less below original ground surface. In the rotary borings Standard Penetration Test (SPT) blowcounts range from 30 to more than 70 blows per foot.

Surface probing with a steel rod during our site reconnaissance also indicated generally dense and difficult to penetrate sandy surficial soils with substantial silt content. Locally within the approach fills and in the cut slope below the abutment, a thin veneer of disturbed and loose sandy soil is present that could be readily penetrated up to about 12 inches (0.3 m) with the probe, and therefore loose materials should be anticipated in some areas in the upper foot (0.3 m).

3.3.1.2 Layer 2: Highly Weathered Granitic Bedrock

This layer as shown on the LOTB begins at approximately 15 feet below the original ground surface, and is inclined at a gradient paralleling the original ground surface. The top of this layer is near El. 415 feet (126.5 m) at Abutment 1 and is near El. 425 feet (129.5 m) at Abutment 3. The layer is described on the LOTB as “very dense mottled brown highly weathered granitic bedrock.” This layer was readily penetrated by a 3-inch rotary boring to depths of 40 feet below the original ground surface, and as such the material is not considered a hard fractured rock. Due to high degree of weathering, this material can be excavated (is rippable) and behaves like a very dense lightly cemented sandy soil. SPT blowcounts exceed 70 blows per foot.

3.3.2 Geologic Structure

Due to high degree of weathering, the granitic rock at the site has been reduced to a soil, and as such is not a fractured rock with structural discontinuities. The material is not sedimentary and as such bedding plane weakness is not an issue. Exposures in the existing cut slopes appear massive and without discernible bedding.

3.3.3 Natural Slope Stability

There are no natural slopes at the site. The existing 2H: 1V cut slopes are stable. The geologic formations at the site are generally not prone to landsliding. The proposed cuts will be stabilized with tiebacks. Therefore, natural slope stability is not an issue for design.

3.3.4 Surface Water

Runoff from the hillsides and roadways is by sheet flow to existing v-ditches and storm drains. No major bodies of surface water or drainage channels are present at the site.

3.3.5 Groundwater

Groundwater was not encountered in the LOTBs to the depths explored (El. 390 feet or 119 meters). Prospect Avenue and the surrounding areas drain to the southwest away from the Abutment 1 slope. No evidence of groundwater or seepage was observed in our site reconnaissance. Excavations for this project will be limited to a few feet below the lowest site grades in SR67. Therefore, the regional groundwater table is unlikely to be encountered in excavations for the tieback wall. However, minor seepage from localized man-made sources is always a possibility.

3.3.6 Engineering Properties

The engineering properties we used for slope stability and foundation analyses were selected conservatively based on our site observations, our experience with similar materials in this area, and back calculation from existing design parameters.

Due to the coarse sandy nature of the site soils, and the high SPT blowcounts, and the geologic origin of the materials, a moderately high friction angle would be expected. Based on the observed silt content and cementation of surface materials, the presence of unsaturated soils due to lack of groundwater, and presence of decomposed granitics, a moderate amount of apparent cohesion would be expected.

To quantify the shear strength parameters that would be consistent with the original foundation design, we back-calculated shear strength parameters using a bearing capacity analysis. We used the method of Brinch-Hansen, which allows computation of ultimate bearing capacity of a cohesive-frictional soil (c-φ soil) including the effect of sloping ground. We assumed a 4-ft (1.2 meter) wide footing embedded 5 feet (1.5 meters) into a 2H:1V slope, and back-calculated reasonable soil parameters that provide for an allowable bearing capacity of 8 ksf (385 kPa) with a factor of safety of 3 on the ultimate value. The resulting parameters are as follows:

• Unit Weight, γ = 130 pcf = 20.4 kN/m3 • Cohesion, c = 260 psf = 12.4 kPa • Friction Angle, φ = 36 degrees

The computation used to back-calculate the parameters is presented in Appendix B. Based on our experience in this type of material, we believe these strengths to be conservative. Further, we conservatively used this strength for both soil and bedrock materials. In computation of earth pressures for design, we neglected the cohesion intercept and used 36-degree friction angle. Our idealized design profile is illustrated in Figure 5.

4.0 ANALYSIS AND RECOMMENDATIONS

4.1 Seismic Study

4.1.1 Regional Seismicity

At the general latitude of San Diego County, the interaction between the North American and Pacific tectonic plates is considered to take place across a wide area extending from the San Andreas fault in the Imperial Valley, to nearly 100 km offshore to the west. The main fault zones west of the San Andreas include the San Jacinto and Elsinore fault zones (east of the project), the Newport-Inglewood / Rose Canyon fault zone (west of the project), and a complex system of northwest trending faults offshore from San Diego. These offshore faults include the Coronado Banks, San Diego Trough, and San Clemente faults. A regional fault map (Caltrans 1996) is shown in Figure 7.

4.1.2 Ground Motion

The site is located in a moderately active seismic area of southern California. Seismic shaking should be anticipated during the life of the project.

We performed a deterministic seismic hazard analysis using the computer program EQFAULT (Blake, 2000). We used the California Geological Survey 2002 (Cao et. al., 2002) fault data file “CGSFLTE.dat” and the Sadigh, et. al. (1997) rock and soil attenuation relationships. The Newport-Inglewood-Rose Canyon/E fault controls the computed acceleration, with a maximum magnitude of 7.2 at a minimum distance of about 22.5-km. Computed site accelerations are 0.20 and 0.21 for soil and rock sites, respectively. EQFAULT outputs are presented in Appendix B. The results are generally consistent with the Caltrans Seismic Hazard Map (Mualchin, 1996), which gives peak bedrock acceleration PBA of about 0.22 g at the site (see Figure 7).

In accordance with Caltrans practice the acceleration is rounded up to 0.3g. For seismic analysis we followed Caltrans Guidelines for Foundation Investigation and Reports Version 1.2 to select the design seismic acceleration for analysis. We used an acceleration coefficient, Kh, of 1/3 of the peak acceleration, or 0.1g for pseudostatic analysis.

4.1.3 Ground Surface Rupture and Displacement Due to Faulting

The site is not located within an Alquist-Priolo Earthquake Fault Zone. Significant segments of active faults are not known to trend toward or through the project site. Therefore, ground rupture is not an issue for design.

4.1.4 Seismic Compaction

Settlement of dry, loose to medium dense, cohesionless sands can occur during seismic shaking. The soils at the site are dense to very dense and as such are not considered susceptible to settlement from seismic shaking. Therefore, potential for seismic compaction is not significant.

4.2 Liquefaction Evaluation

Liquefaction involves a sudden loss in strength of a saturated, cohesionless soil (sand, silty sand, sandy silt) caused by cyclic loading such as an earthquake. This results in temporary transformation of the soil to a fluid mass. Typically, liquefaction occurs in areas where groundwater is less than about 60 feet (18 m) from the surface and where the soils contain layers of loose to medium dense saturated cohesionless soils. No groundwater or liquefiable soils were identified at the site, and therefore liquefaction potential is not significant.

4.3 Corrosion Evaluation

The latest Caltrans corrosion requirements are defined in Caltrans Corrosion Guidelines (Version 1.0, September 2003). This document defines a corrosive area as follows:

“For structural elements, the Department considers a site to be corrosive if one or more of the following conditions exist for the representative soil and/or water samples taken at the site:

Chloride concentration is 500 ppm or greater, sulfate concentration is 2000 ppm or greater, or the pH is 5.5 or less.”

Based on our experience in sandy decomposed granitics and these Caltrans criteria, the on-site soils/rock are not likely to classify as corrosive to concrete. However, no site-specific corrosion data are available. Prior to or during construction it is recommended that corrosion testing including pH, Sulfate, Chloride, and Minimum Resistivity tests be run on representative materials from the wall area to determine the mix design requirements for reinforced concrete. Alternatively, a corrosive soil mix design may be used in lieu of testing. If required,

N:\Projects\_AV\I300\I-391 Tieback Wall - Prospect Ave. OC\Report\I-391 FR SR67 Prospect Ave OC Tieback Wall.doc Foundation Report, Proposed Tieback Retaining Wall February 9, 2006 Abutment 1 – SR67 Prospect Ave. OC, San Diego County, CA Page 10 Parsons Brinckerhoff Quade & Douglas GDC Project No. I-391 corrosion mitigation requirements for reinforced concrete structural elements for chloride, acid, and sulfate environments are listed in Section 10 of Caltrans Corrosion Guidelines (Version 1.0, September 2003) and Bridge Design Specifications Article 8.22.

Tieback anchors for permanent walls should be designed with a double corrosion protection system, which consists of encapsulation in a corrugated plastic sheath, and grouting both inside and outside the sheath. Corrosion protection for tiebacks should follow the latest Caltrans requirements.

4.4 Scour Evaluation

No natural or man-made drainage channels are present in the wall vicinity. Therefore, scour potential is not significant.

4.5 Foundation Recommendations

4.5.1 General

The proposed tieback wall is considered feasible from a geotechnical standpoint. The idealized geotechnical design profile is illustrated in Figure 5. We recommend the following general requirements:

• Anchor inclination should be 15 degrees to the horizontal; • Unbonded length should be a minimum of 20 feet (6.1 meters); • Excavation should be performed in lifts not to exceed 6 feet (1.8 meters) in vertical height; • Anchor loads should be estimated using both earth pressure methods and limit equilibrium slope stability (trial slip surface) methods, and the more critical anchor loads used for design; • To mitigate sloughing potential, temporary excavations should not be left unsupported or exposed for more time than necessary. The time of exposed unsupported cut should be limited to 72 hours unless determined by field observation to be stable for longer periods by the project geotechnical engineer.

4.5.2 Grout-Soil Bond Stress in Bonded Zone

The tieback contractor should select the design bond stress, drill hole diameter, and length of bonded zone in order to provide the design capacity specified by the

N:\Projects\_AV\I300\I-391 Tieback Wall - Prospect Ave. OC\Report\I-391 FR SR67 Prospect Ave OC Tieback Wall.doc Foundation Report, Proposed Tieback Retaining Wall February 9, 2006 Abutment 1 – SR67 Prospect Ave. OC, San Diego County, CA Page 11 Parsons Brinckerhoff Quade & Douglas GDC Project No. I-391 structural engineers. The capacity of each anchor should be load tested during construction to at least 1.5 times the design capacity in accordance with Caltrans requirements.

4.5.3 Earth Pressures

We developed lateral earth pressures for design of the tieback wall in accordance with Bridge Design Specifications (BDS) August 2003 as follows:

• BDS 5.5.5.7 – Lateral Earth Pressures for Anchored Walls • Active earth pressure was determined by Coulomb’s theory including the effect of 2H:1V sloping ground and using zero wall friction. We used a soil friction angle of 36 degrees and neglected any apparent cohesion. The

active pressure resultant on the tieback wall (Pa) was increased to 1.44 Pa to account for anchored wall conditions per BDS. • Lateral pressure on tieback wall from vertical footing surcharge load was determined using BDS 5.5.5.10.2, which is appropriate for a rigid wall. • Lateral pressure on tieback wall from sliding friction on abutment footing was determined using BDS Figure 5.5.5.10.4-2. • Seismic earth pressure was determined using 1.44 times the Mononabe-Okabe adaptation of Coulomb’s method, with zero wall friction, 36 degree friction angle, 2H:1V slope, and pseudo-static acceleration of 0.1g; • Combined earth pressure on the tieback wall was taken as 1.44 times active pressure plus full vertical footing surcharge and sliding friction footing surcharge for static conditions, and for seismic condition 1.44 times Mononabe-Okabe earth pressure in an inverted triangular distribution was added to the static pressures.

The total pressures were distributed for design as trapezoidal in accordance with BDS 5.5.5.7. The recommended total earth pressures are presented graphically in Figure 8a and 8b for static and static plus seismic conditions, respectively. Computations are presented in Appendix B. The total wall load is approximately 12.1 kips per foot for static conditions and 13.5 kips per foot for static plus seismic. Assuming a horizontal spacing of 15 feet between tiebacks and two levels of equally loaded tiebacks, the resulting tieback loads would be 91 kips and 101 kips per tieback, for static and static + seismic loading, respectively.

4.5.4 Wall Stability Check by Limit Equilibrium Methods

Slope stability for the tieback wall / slope / abutment footing system was checked using limit equilibrium methods and anchor loads developed from earth pressure analysis. The results of these analyses indicate that the earth pressure approach results in higher anchor load requirements, and therefore controls the design. The analyses and results are discussed in more detail in Section 4.6.

4.5.5 Wall Drainage

Proper drainage is required to prevent the potential negative effects of surface water and groundwater on the wall and abutment. This includes surface and subsurface drainage, as described below.

4.5.5.1 Surface Drainage

A v-ditch (based on standard Caltrans details) is recommended along the top of the wall to intercept surface runoff from the slope above.

4.5.5.2 Wall Drainage

Vertical drains should be placed at regular horizontal intervals not to exceed 7.5 feet (2.3 m) against the soil backcut behind the wall facing to intercept any groundwater seeps that could occur. This typically consists of 12-inch (300-mm) strips of geocomposite drainboard discharging to weep holes near the base of the wall.

4.5.6 Vertical Component of Tieback Load (Friction and Bearing)

The vertical components of the tieback loads are typically carried by friction on the back of the wall and/or bearing on the base of the wall, depending on anchor inclination and coefficient of friction. Coefficient of sliding friction between on-site 2 o soil / weathered bedrock and shotcrete may be taken as tan δ = /3 tan (36 ) = 0.48. For α = 15-degree anchor inclination the entire vertical component of the anchor tension P may be resisted by friction alone and bearing is not required (P cos α tan δ / P sin α > 1.5). If necessary, allowable bearing capacity at the base of the tieback wall may be taken as 8 ksf. The bottom of the wall should be embedded at least 1 ft below adjacent roadway grade.

4.5.7 Load Testing

All anchors should be load tested for acceptance in accordance with current Caltrans criteria.

4.6 Slope Stability

4.6.1 General

Slope stability was checked using limit equilibrium methods for both the permanent wall / slope and for the temporary excavation condition. The analysis included both the Modified Bishop’s method for circular failure surfaces using the computer program PCSTABL5M, and 2-part wedge analysis using the Caltrans computer program SNAILZ. The calculations used anchor lockoff loads determined from earth pressure analysis, and the geometry and shear strength profile illustrated in Figure 5. Surcharge from the bridge abutment footing was modeled as a uniform vertical surcharge pressure of 8 ksf (385 kPa) on a 4 foot (1.2 meter) wide footing. Traffic surcharge on the roadway above was modeled as a uniform vertical surcharge pressure of 240 psf (11.5 kPa).

4.6.2 Factor of Safety

The following factor of safety criteria were used to check the slope for adequate stability in accordance with Section 5 of BDS (August 2003) and Caltrans Guidelines for Foundation Investigations and Reports Version 1.2:

• Static analysis: Minimum Factor of Safety = 1.50 • Pseudostatic analysis: Minimum Factor of Safety = 1.10 • Temporary excavation: Minimum Factor of Safety = 1.25

Results of the analyses are presented in the following sections.

4.6.3 Global Stability of Tieback Wall and Permanent Slope

4.6.3.1 Static Analysis

Static analysis was performed with PCSTABL5M and SNAILZ utilizing anchor loads from the earth pressure analysis and the design profile of Figure 5. Static factors of safety exceed the minimum required value of 1.50 (static factor of safety of 1.9 and 1.8, respectively). The results of the static PCSTABL5M and SNAILZ analyses are presented graphically in Figure 9, and are attached in Appendix B.

4.6.3.2 Pseudo-Static Analysis

Pseudostatic seismic analysis was performed with PCSTABL5M and SNAILZ computer programs utilizing anchor loads from the earth pressure analysis, a pseudostatic acceleration coefficient of Kh=0.1 (or 1/3 of PGA), and the design profile of Figure 5. Pseudo-static factors of safety exceed the minimum required value of 1.1 (Factor of Safety of 1.8 and 1.5, respectively). The results of the pseudostatic PCSTABL5M and SNAILZ analyses are presented graphically in Figure 10, and are attached in Appendix B.

4.6.4 Stability of Temporary Excavations

Incremental temporary cuts in two stages, performed from the top down, will be performed for construction of the tieback wall. The wall facing will be constructed and the tiebacks will be installed, tested, and locked off for the upper row prior to advancing the excavation to the lower level. The temporary cuts will be stabilized permanently by the tieback system.

We checked the stability of the construction backcut using the design profile of Figure 5 and upper stage excavation of 6 feet (1.8 m), and full excavation of 10 feet (3 meters). The analysis included the vertical load on the abutment footing as an 8-ksf (385 kPa) surcharge over a 4-foot (1.2 meter) footing width. The results of the calculations are shown in Figures 11a and 11b.

The results of the analysis using the adopted design profile indicate:

• For 6-foot (1.8 m) first stage excavation with no tiebacks computed Factor of Safety is 1.50 and exceeds the minimum of 1.25 for temporary excavation; • For a 10-foot (3 meter) excavation with no tiebacks calculated Factor of Safety is 1.07, which is less than the 1.25 required for temporary excavation; • For a 10-foot (3 meter) excavation with the upper tieback locked off at the design load and prior to tensioning the lower tieback, calculated factor of safety is 1.38, which exceeds the minimum 1.25 required.

Based on this we recommend that:

• Excavation should be done in two stages; • The first stage should not exceed 6 feet (1.8 meters) in vertical height;

• The upper row of tiebacks should be locked off at the design force prior to excavating the second lift.

4.7 Construction Considerations

4.7.1 Construction Advisories

Care should be taken during excavation to maintain support of the bridge abutment. Experienced geotechnical personnel should observe the excavation during construction. If excavation conditions are different than those inferred from the LOTB, this office should be notified at once to provide an appropriate recommendation.

4.7.2 Excavation

All earthwork and grading should be performed in accordance with Section 19 of Caltrans Standard Specifications. Excavated soils will consist primarily of dense to very dense silty sands and highly weathered granitic bedrock. Based on the depth drilled on the LOTB (Figure 6) it is expected that the soils and weathered rock should be excavatable with moderate to heavy effort using heavy-duty grading equipment. Local zones of moderate to strong cementation could be encountered.

Temporary excavations will be susceptible to erosion if exposed to surface runoff. If work is done during periods of rain, the contractor will have to make provisions to control the flow of water through the work area and to maintain a dry excavation. Surface drainage should be controlled along the top of slope to avoid water run-off running into the excavation and eroding the excavation face. This is typically accomplished by covering the slope and excavation with Visqueen and sandbags.

The excavation face should be shotcreted as soon as possible after excavation. If excessive sloughing is observed, measures such as a temporary shotcrete facing may be needed to stabilize the face.

No surcharge loads, such as the weight of heavy equipment or materials, should be placed above the top of excavations. Care should be taken during excavation to avoid removing support for any existing improvements, such as foundations, pavements and buried utilities.

4.7.3 Buried Utilities

The contractor should research utility locations and take the necessary precautions to protect-in-place or relocate utilities prior to grading or anchor installation.

4.7.4 Remnants of Previous Construction

Construction of this project may require the removal of existing facilities, including structures, v-ditches, pavements, fencing, walls, asphalt, concrete, buried utilities, and other improvements.

4.7.5 Hazardous Waste Considerations

We did not perform an investigation for hazardous materials at the site. Based on limited surface observation, no visible evidence of contamination was observed. Caltrans procedures for identification, handling, and disposal of potentially contaminated soils should be followed as necessary during construction.

4.7.6 Differing Site Conditions

Our characterization of the site is based on the as-built plans and LOTB, estimation of earth material properties, and geotechnical analyses of a typical cross-section. All cuts, excavations, and foundation areas should be observed during construction to verify they are consistent with the assumptions and recommendations used in the design. If field conditions during construction appear to be different than is indicated in this report, we should be notified immediately so that we may assess the impact of such conditions on our recommendations.

5.0 REFERENCES

Blake, T. F., "EQFAULT - A Computer Program for the Deterministic Prediction of Peak Horizontal Acceleration from Digitized California Faults," 2000.

California Department of Conservation, Division of Mines and Geology, 1994, “Fault-Rupture Hazard Zones in California, Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zone Mays,” Special Publication 42.

Caltrans, 2003, “Corrosion Guidelines, Version 1.0,” California Department of Transportation Division of Engineering Services, Materials Engineering and Testing Services, September 2003.

Caltrans Bridge Design Specifications, August 2003.

Caltrans, 2002, Guidelines for Foundation Investigations and Reports, Version 1.2, June 2002, Caltrans Division of Engineering Services, Geotechnical Services.

Caltrans, 1995, Standard Plans and Specifications, Business, Transportation and Housing Agency, Sacramento, California.

Caltrans, SNAILwin, Caltrans Soil Nail Computer Program, Version 3.10.

Kennedy, M.P., and Peterson, G.L., 1975, Geology of San Diego Metropolitan Area, California: California Division of Mines and Geology Bulletin 200.

Kennedy, M.P., Greene, H.G., Clarke, S.H., and Bailey, K.A., 1980, “Recency and Character of Faulting Offshore, Metropolitan San Diego, California,” California Division of Mines and Geology Map Sheet 41.

Mualchin, L., 1996, “California Seismic Hazard Map 1996, Based on Maximum Credible Earthquakes (MCE)”, Prepared by the California Department of Transportation, Engineering Service Center, Office of Earthquake Engineering, Sacramento, California.

Mualchin, L., 1996, “A Technical Report to Accompany the Caltrans California Seismic Hazard Map 1996,” A report prepared by the California Department of Transportation, Engineering Service Center, Office of Earthquake Engineering, Sacramento, California, dated July 1996.

Purdue University, Computer Program “PCSTABL5M – Slope Stability Analysis, Simplified Janbu, Simplified Bishop, or Spencer’s Method of Slices.”

Seed, H.B. and Silver, M.L., 1972, Settlement of Dry Sands During Earthquakes, J. of Soil Mech. Found. Div., ASCE, Vol. 98, No. 4, pp. 381-397.

Seed, H.B. and Whitman, R.V., "Design of Earth Retaining Structures for Dynamic Loads, " Lateral Stresses in the Ground and Design of Earth Retaining Structures, Proceedings of a Specialty Conference Sponsored by ASCE, Cornell University, Ithaca, N.Y., 1970.

Tokimatsu, K. and Seed, H.B., 1987, Evaluation of Settlements in Sands Due to Earthquake Shaking, J. of Geotech. Eng. Div., ASCE, Vol. 113, No. 8.

Whitman, R.V. and Christian, 1990, “Seismic Response of Retaining Structures,” Proceedings of Port of Los Angeles Seismic Workshop, March 21-23, 1990.

6.0 LIMITATIONS

Our investigation and evaluations were performed in accordance with generally accepted local standards using that 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 report.

The recommendations for this project are made contingent on the opportunity of GDC to observe construction operations including excavation. If parties other than GDC are engaged to provide such services, they must be notified that they will be required to assume complete responsibility for the geotechnical phase of the project by concurring with the recommendations in this report or provide alternate recommendations as deemed appropriate.

N:\Projects\_AV\I300\I-391 Tieback Wall - Prospect Ave. OC\Report\I-391 FR SR67 Prospect Ave OC Tieback Wall.doc

FIGURES GDC Project No. I-391

Prospect Avenue OC San Diego County,California Vicinity Map Figure 1a GDC Project No. I-391

Prospect Avenue OC San Diego County,California Location Map Figure 1b

GDC Project No. I-391

Prospect Avenue OC San Diego County,California Static Earth Pressure Diagram Figure 8a GDC Project No. I-391

Prospect Avenue OC San Diego County,California Seismic Earth Pressure Diagram Figure 8b GDC Project No. I-391

Prospect Avenue OC STATIC ANALYSIS OF FINAL San Diego County,California CONFIGURATION WITH LOAD Static Stability Results OF TWO TIEBACKS (202 k @ 15’). For Permanent Wall Figure 9a GDC Project No. I-391

Prospect Avenue OC SEISMIC ANALYSIS OF FINAL San Diego County,California CONFIGURATION WITH LOAD Seismic Stability Results OF TWO TIEBACKS (202 k @ 15’). For Permanent Wall Figure 10 GDC Project No. I-391

Prospect Avenue OC TEMPORARY EXCAVATION OF San Diego County,California 6 FT NO TIEBACKS– FACTORS Temporary Excavation OF SAFETY IN FRONT OF AND Stability Results BEHIND ABUTMENT FOOTING. Figure 11a GDC Project No. I-391

Prospect Avenue OC TEMPORARY EXCAVATION OF San Diego County,California 10 FT WITH ONLY UPPER Temporary Excavation TIEBACK ANCHOR INSTALLED. Stability Results Figure 11b

APPENDIX A SITE PHOTOGRAPHS

APPENDIX B ANALYSES AND CALCULATIONS

BACK CALCULATION OF STRENGTH PARAMETERS BEARING CAPACITY OF FOOTING ON A SLOPE BRINCH-HANSEN METHOD

BEARING CAPACITY ANALYSIS BRINCH-HANSEN METHOD

<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>> Footing Type C C=continuous, R=rectangular Footing Width 0.76 m 2.50 ft Footing Length 0.00 m ft Footing Depth 1.52 m 5.00 ft Ground Inclination 26.56 deg 26.56 deg Soil Cohesion 12.56 kPa 262.31 psf Soil Friction Angle 36.00 deg 36.00 deg Soil Unit Weight 20.42 kN/m3 130.00 pcf Water Depth 30.48 m 100.00 ft Safety Factor 3.00 3.000

<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>> Ground Inclination Bearing Capacity Shape Factors Depth Factors Factors Factors Sc= 1.000 k= 1.107 Gc= 0.819 Nq= 37.75 Sca= 0.000 Dc= 1.443 Gca= 0.181 Nc= 50.59 Sq= 1.000 Dca= 0.443 Gq= 0.237 Nγ= 40.05 Sγ= 1.000 Dq= 1.273 Gγ= 0.237 Dγ= 1.000 Effective Unit Weight (kN/m3) (pcf) Effective Stress at Depth D γ'= 20.4 130.0 31.13 kPa 650 psf Net Allowable Bearing Capacity (kPa) Net Allowable Bearing Capacity (ksf) q'all= 383 q'all= 8.00 BEARING CAPACITY ANALYSIS BRINCH-HANSEN METHOD

<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>> Footing Type C C=continuous, R=rectangular Footing Width 0.61 m 2.00 ft Footing Length 0.00 m ft Footing Depth 0.30 m 1.00 ft Ground Inclination 0.00 deg 0.00 deg Soil Cohesion 12.45 kPa 260.00 psf Soil Friction Angle 36.00 deg 36.00 deg Soil Unit Weight 20.42 kN/m3 130.00 pcf Water Depth 30.48 m 100.00 ft Safety Factor 3.00 3.000

<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>> Ground Inclination Bearing Capacity Shape Factors Depth Factors Factors Factors Sc= 1.000 k= 0.500 Gc= 1.000 Nq= 37.75 Sca= 0.000 Dc= 1.200 Gca= 0.000 Nc= 50.59 Sq= 1.000 Dca= 0.200 Gq= 1.000 Nγ= 40.05 Sγ= 1.000 Dq= 1.123 Gγ= 1.000 Dγ= 1.000 Effective Unit Weight (kN/m3) (pcf) Effective Stress at Depth D γ'= 20.4 130.0 6.23 kPa 130 psf Net Allowable Bearing Capacity (kPa) Net Allowable Bearing Capacity (ksf) q'all= 421 q'all= 8.79

EARTH PRESSURE CALCULATIONS

COULOMB AND MONONABE-OKABE EARTH PRESSURE CALCULATIONS

<> 3 Unit Weight = γ = 130 pcf = 20.4 kN/m COULOMB STATIC M-O SEISMIC INCREMENT

Friction Angle = φ = 36 degrees = 0.628319 radians EFPiA EFP iAE φ = Wall Friction Angle = w 0.0 degrees = 0 radiansKA pcf kN/m3 degKAE-KA pcf kN/m3 deg Wall Inclination = α = 0 degrees = 0 radians 0.371 48.2 7.6 54.8 0.146 18.9 3.0 44.72

Slope Inclination = β = 26.560 degrees = 0.463559 radians RANKINE STATIC max Kh= 0.166266274506736

Horiz. EQ Coeff. = Kh = 0.100 =1/3*PGA 0.402 52.3 8.2 63.0 max β= 30.28940686250040 deg

Vert. EQ Coeff. = Kv = 0

<< COULOMB CALCULATION>> STATIC ACTIVE EARTH PRESSURE STATIC CRITICAL INCLINATION

ABCDEKA C1 C2 iA degrees 36.0 0.0 36.0 9.4 26.6 54.79 radians 0.628 0.000 0.628 0.165 0.464 0.371 0.506 1.000 0.956221

SEISMIC ACTIVE EARTH PRESSURE SEISMIC CRITICAL INCLINATION

θ A' B' C' D' E' KAE C1E C2E iAE degrees 5.7 30.3 5.7 36.0 3.7 26.56 44.72 radians 0.100 0.529 0.100 0.628 0.065 0.464 0.517 0.368 1.178 0.780592

Print Date GROUP DELTA CONSULTANTS, INC. Coulomb.xls calc 2/8/2006 LATERAL PRESSURE ON RIGID WALL DUE TO VERTICAL STRIP LOAD PARALLEL TO WALL

BDS Eqn. 5.5.5.10.2-1

Total Soil Reaction = 24 kips 106.8 kN Actual Bearing Width= 4 feet 1.22 m a = Equiv. Width, B' = 4.00 feet 1.22 m p = Meyerhoff Pressure= 6.00 ksf 287 kPa b = offset from wall = 10.00 feet 3.05 m BDS Equation

Depth, z ∆ph ∆ph Depth, z Depth, z (ft) ABCDEF(ksf) (kPa) (ft) (m) 0.0 3.82 0.017453 90.000 90.000 7.143E-12 1E-11 0.00 0.0 0.0 0.0 0.5 3.82 0.017453 87.955 87.138 3.567E-02 0.0498753 0.11 5.2 0.5 0.2 1.0 3.82 0.017453 85.914 84.289 7.107E-02 0.0990099 0.22 10.3 1.0 0.3 1.5 3.82 0.017453 83.884 81.469 1.059E-01 0.1466993 0.32 15.2 1.5 0.5 2.0 3.82 0.017453 81.870 78.690 1.400E-01 0.1923077 0.41 19.7 2.0 0.6 2.5 3.82 0.017453 79.875 75.964 1.731E-01 0.2352941 0.50 23.9 2.5 0.8 3.0 3.82 0.017453 77.905 73.301 2.049E-01 0.2752294 0.58 27.6 3.0 0.9 3.5 3.82 0.017453 75.964 70.710 2.353E-01 0.311804 0.64 30.8 3.5 1.1 4.0 3.82 0.017453 74.055 68.199 2.642E-01 0.3448276 0.70 33.4 4.0 1.2 4.5 3.82 0.017453 72.181 65.772 2.913E-01 0.3742204 0.74 35.6 4.5 1.4 5.0 3.82 0.017453 70.346 63.435 3.167E-01 0.4 0.78 37.3 5.0 1.5 5.5 3.82 0.017453 68.552 61.189 3.403E-01 0.4222649 0.80 38.5 5.5 1.7 6.0 3.82 0.017453 66.801 59.036 3.621E-01 0.4411765 0.82 39.3 6.0 1.8 6.5 3.82 0.017453 65.095 56.976 3.820E-01 0.456942 0.83 39.6 6.5 2.0 7.0 3.82 0.017453 63.435 55.008 4.000E-01 0.4697987 0.83 39.7 7.0 2.1 7.5 3.82 0.017453 61.821 53.130 4.163E-01 0.48 0.82 39.4 7.5 2.3 8.0 3.82 0.017453 60.255 51.340 4.308E-01 0.4878049 0.81 38.9 8.0 2.4 8.5 3.82 0.017453 58.736 49.635 4.436E-01 0.4934688 0.80 38.2 8.5 2.6 9.0 3.82 0.017453 57.265 48.013 4.549E-01 0.4972376 0.78 37.3 9.0 2.7 9.5 3.82 0.017453 55.840 46.469 4.646E-01 0.499343 0.76 36.3 9.5 2.9 10.0 3.82 0.017453 54.462 45.000 4.730E-01 0.5 0.73 35.1 10.0 3.0 10.5 3.82 0.017453 53.130 43.603 4.800E-01 0.4994055 0.71 34.0 10.5 3.2 11.0 3.82 0.017453 51.843 42.274 4.858E-01 0.4977376 0.68 32.7 11.0 3.4 11.5 3.82 0.017453 50.599 41.009 4.905E-01 0.4951561 0.66 31.5 11.5 3.5 12.0 3.82 0.017453 49.399 39.806 4.941E-01 0.4918033 0.63 30.2 12.0 3.7 12.5 3.82 0.017453 48.240 38.660 4.968E-01 0.4878049 0.60 28.9 12.5 3.8 13.0 3.82 0.017453 47.121 37.569 4.986E-01 0.4832714 0.58 27.7 13.0 4.0 13.5 3.82 0.017453 46.042 36.529 4.997E-01 0.4782994 0.55 26.5 13.5 4.1 14.0 3.82 0.017453 45.000 35.538 5.000E-01 0.472973 0.53 25.3 14.0 4.3 14.5 3.82 0.017453 43.995 34.592 4.997E-01 0.467365 0.50 24.1 14.5 4.4 15.0 3.82 0.017453 43.025 33.690 4.988E-01 0.4615385 0.48 23.0 15.0 4.6 STATIC EARTH PRESSURES VERSUS DEPTH

Static Footing Footing 1.44x Sliding Total Total Vertical Active Friction Surcharge Earth Surcharge Static Static Depth Depth below top Net below top of wall, z ∆ph ∆ph ∆ph Pressure Resultant of wall, z (ft) (ksf) (ksf) (ksf) (ksf) (k/ft) (ft) 0.0 0.000 0.000 0.290 0.290 0.000 0.0 0.5 0.109 0.035 0.284 0.428 0.179 0.5 1.0 0.215 0.069 0.279 0.564 0.427 1.0 1.5 0.317 0.104 0.274 0.695 0.742 1.5 2.0 0.412 0.139 0.268 0.819 1.120 2.0 2.5 0.499 0.174 0.263 0.935 1.559 2.5 3.0 0.576 0.208 0.258 1.042 2.053 3.0 3.5 0.642 0.243 0.253 1.138 2.598 3.5 4.0 0.699 0.278 0.247 1.224 3.189 4.0 4.5 0.744 0.313 0.242 1.299 3.819 4.5 5.0 0.779 0.347 0.237 1.363 4.485 5.0 5.5 0.804 0.382 0.232 1.417 5.180 5.5 6.0 0.820 0.417 0.226 1.463 5.900 6.0 6.5 0.828 0.451 0.221 1.500 6.641 6.5 7.0 0.828 0.486 0.216 1.530 7.398 7.0 7.5 0.823 0.521 0.211 1.554 8.170 7.5 8.0 0.812 0.556 0.205 1.573 8.951 8.0 8.5 0.797 0.590 0.200 1.588 9.742 8.5 9.0 0.779 0.625 0.195 1.598 10.538 9.0 9.5 0.757 0.660 0.190 1.607 11.339 9.5 10.0 0.734 0.695 0.184 1.613 12.144 10.0 <---For 10 ft high wall 10.5 0.709 0.729 0.179 1.618 12.952 10.5 11.0 0.684 0.764 0.174 1.621 13.762 11.0 11.5 0.657 0.799 0.168 1.624 14.573 11.5 12.0 0.631 0.833 0.163 1.627 15.386 12.0 12.5 0.604 0.868 0.158 1.630 16.200 12.5 13.0 0.578 0.903 0.153 1.634 17.016 13.0 13.5 0.553 0.938 0.147 1.638 17.834 13.5 14.0 0.528 0.972 0.142 1.642 18.654 14.0 14.5 0.503 1.007 0.137 1.647 19.476 14.5 15.0 0.480 1.042 0.132 1.653 20.302 15.0 TRAPEZOIDAL DISTRIBUTION OF STATIC EARTH PRESSURE ON TIEBACK WALL

Tieback Wall with 2 Levels of Anchors

INPUT H= 10 feet Static Earth Pressure Diagram Prospect Ave OC 10 ft H1= 3 feet high Tieback Wall H3= 3 feet H2= 4 feet Pressure (ksf) Ptotal= 12.14431 kip/foot 0 0.5 1 1.5 2 0 CALC pa= 1.518 ksf

PLOT 2

Pressure Depth (ksf) (feet) 4 00 1.518 2 1.518 8

010 Depth (feet) 6

Hor. Tie Spacing= 15 feet 8 Total Tie Force= 182.1647 kips # Ties= 2 Static Tie 10 Load= 91 kips/tie SEISMIC EARTH PRESSURES VERSUS DEPTH

Seismic

Footing 1.44x 1.44 x Sliding Total Total Footing Active Mononabe - Friction Surcharge Earth Okabe Surcharge Seismic Seismic Depth Depth below top Net below top of wall, z ∆ph ∆ph ∆ph ∆ph Pressure Resultant of wall, z (ft) (ksf) (ksf) (ksf) (ksf) (ksf) (k/ft) (ft) 0.0 0.000 0.000 0.273 0.290 0.563 0.000 0.0 0.5 0.109 0.035 0.260 0.284 0.687 0.313 0.5 1.0 0.215 0.069 0.246 0.279 0.810 0.687 1.0 1.5 0.317 0.104 0.232 0.274 0.927 1.121 1.5 2.0 0.412 0.139 0.219 0.268 1.038 1.612 2.0 2.5 0.499 0.174 0.205 0.263 1.140 2.157 2.5 3.0 0.576 0.208 0.191 0.258 1.233 2.750 3.0 3.5 0.642 0.243 0.178 0.253 1.316 3.387 3.5 4.0 0.699 0.278 0.164 0.247 1.388 4.063 4.0 4.5 0.744 0.313 0.150 0.242 1.449 4.773 4.5 5.0 0.779 0.347 0.137 0.237 1.500 5.510 5.0 5.5 0.804 0.382 0.123 0.232 1.540 6.270 5.5 6.0 0.820 0.417 0.109 0.226 1.572 7.048 6.0 6.5 0.828 0.451 0.096 0.221 1.596 7.840 6.5 7.0 0.828 0.486 0.082 0.216 1.612 8.642 7.0 7.5 0.823 0.521 0.068 0.211 1.623 9.451 7.5 8.0 0.812 0.556 0.055 0.205 1.628 10.263 8.0 8.5 0.797 0.590 0.041 0.200 1.629 11.077 8.5 9.0 0.779 0.625 0.027 0.195 1.626 11.891 9.0 9.5 0.757 0.660 0.014 0.190 1.620 12.703 9.5 10.0 0.734 0.695 0.000 0.184 1.613 13.511 10.0 <---For 10 ft high wall TRAPEZOIDAL DISTRIBUTION OF SEISMIC EARTH PRESSURE ON TIEBACK WALL

Tieback Wall with 2 Levels of Anchors

INPUT H= 10 feet Seismic Earth Pressure Diagram Prospect Ave OC 10 H1= 3 feet ft high Tieback Wall H3= 3 feet H2= 4 feet Pressure (ksf) Ptotal= 13.51087 kip/foot 0 0.5 1 1.5 2 0 CALC pa= 1.689 ksf

PLOT 2

Pressure Depth (ksf) (feet) 4 00 1.689 2 1.689 8

010 Depth (feet) 6

Hor. Tie Spacing= 15 feet 8 Total Tie Force= 202.6631 kips # Ties= 2 Seismic 10 Tie Load= 101 kips/tie

EQFAULT OUTPUT

i391.OUT

*********************** * * * E Q F A U L T * * * * Version 3.00 * * * *********************** DETERMINISTIC ESTIMATION OF PEAK ACCELERATION FROM DIGITIZED FAULTS

JOB NUMBER: I-391 DATE: 01-19-2006 JOB NAME: SR67 - Prospect Ave OC

CALCULATION NAME: Sadigh Rock

FAULT-DATA-FILE NAME: C:\Program Files\EQFAULT1\CGSFLTE.DAT

SITE COORDINATES: SITE LATITUDE: 32.8310 SITE LONGITUDE: 116.9619

SEARCH RADIUS: 62 mi

ATTENUATION RELATION: 20) Sadigh et al. (1997) Horiz. - Soil UNCERTAINTY (M=Median, S=Sigma): M Number of Sigmas: 0.0 DISTANCE MEASURE: clodis SCOND: 0 Basement Depth: 5.00 km Campbell SSR: Campbell SHR: COMPUTE PEAK HORIZONTAL ACCELERATION

FAULT-DATA FILE USED: C:\Program Files\EQFAULT1\CGSFLTE.DAT

MINIMUM DEPTH VALUE (km): 0.0

Page 1 i391.OUT

------EQFAULT SUMMARY ------

------DETERMINISTIC SITE PARAMETERS ------Page 1 ------| |ESTIMATED MAX. EARTHQUAKE EVENT | APPROXIMATE |------ABBREVIATED | DISTANCE | MAXIMUM | PEAK |EST. SITE FAULT NAME | mi (km) |EARTHQUAKE| SITE |INTENSITY | | MAG.(Mw) | ACCEL. g |MOD.MERC. ======|======|======|======|======ROSE CANYON | 14.0( 22.5)| 7.2 | 0.205 | VIII CORONADO BANK | 26.9( 43.3)| 7.6 | 0.143 | VIII ELSINORE (JULIAN) | 28.3( 45.6)| 7.1 | 0.100 | VII EARTHQUAKE VALLEY | 32.7( 52.7)| 6.5 | 0.055 | VI NEWPORT-INGLEWOOD (Offshore) | 35.2( 56.7)| 7.1 | 0.078 | VII ELSINORE (COYOTE MOUNTAIN) | 36.0( 58.0)| 6.8 | 0.061 | VI ELSINORE (TEMECULA) | 37.8( 60.9)| 6.8 | 0.057 | VI SAN JACINTO-COYOTE CREEK | 49.4( 79.5)| 6.6 | 0.035 | V SAN JACINTO-ANZA | 51.0( 82.0)| 7.2 | 0.053 | VI SAN JACINTO - BORREGO | 51.4( 82.7)| 6.6 | 0.033 | V ELSINORE (GLEN IVY) | 60.4( 97.2)| 6.8 | 0.031 | V SUPERSTITION MTN. (San Jacinto) | 61.4( 98.8)| 6.6 | 0.025 | V ******************************************************************************* -END OF SEARCH- 12 FAULTS FOUND WITHIN THE SPECIFIED SEARCH RADIUS.

THE ROSE CANYON FAULT IS CLOSEST TO THE SITE. IT IS ABOUT 14.0 MILES (22.5 km) AWAY.

LARGEST MAXIMUM-EARTHQUAKE SITE ACCELERATION: 0.2053 g

*********************** * * * E Q F A U L T * * * * Version 3.00 * * * *********************** DETERMINISTIC ESTIMATION OF PEAK ACCELERATION FROM DIGITIZED FAULTS

JOB NUMBER: I-391 DATE: 01-19-2006

JOB NAME: SR67 - Prospect Ave OC CALCULATION NAME: Sadigh Rock

FAULT-DATA-FILE NAME: C:\Program Files\EQFAULT1\CGSFLTE.DAT Page 2 i391.OUT

SITE COORDINATES: SITE LATITUDE: 32.8310 SITE LONGITUDE: 116.9619 SEARCH RADIUS: 62 mi ATTENUATION RELATION: 21) Sadigh et al. (1997) Horiz. - Rock UNCERTAINTY (M=Median, S=Sigma): M Number of Sigmas: 0.0 DISTANCE MEASURE: clodis SCOND: 0 Basement Depth: 5.00 km Campbell SSR: Campbell SHR: COMPUTE PEAK HORIZONTAL ACCELERATION FAULT-DATA FILE USED: C:\Program Files\EQFAULT1\CGSFLTE.DAT

MINIMUM DEPTH VALUE (km): 0.0

------EQFAULT SUMMARY ------

------DETERMINISTIC SITE PARAMETERS ------Page 1 ------| |ESTIMATED MAX. EARTHQUAKE EVENT | APPROXIMATE |------ABBREVIATED | DISTANCE | MAXIMUM | PEAK |EST. SITE FAULT NAME | mi (km) |EARTHQUAKE| SITE |INTENSITY | | MAG.(Mw) | ACCEL. g |MOD.MERC. ======|======|======|======|======ROSE CANYON | 14.0( 22.5)| 7.2 | 0.214 | VIII CORONADO BANK | 26.9( 43.3)| 7.6 | 0.133 | VIII Page 3 i391.OUT ELSINORE (JULIAN) | 28.3( 45.6)| 7.1 | 0.089 | VII EARTHQUAKE VALLEY | 32.7( 52.7)| 6.5 | 0.046 | VI NEWPORT-INGLEWOOD (Offshore) | 35.2( 56.7)| 7.1 | 0.066 | VI ELSINORE (COYOTE MOUNTAIN) | 36.0( 58.0)| 6.8 | 0.050 | VI ELSINORE (TEMECULA) | 37.8( 60.9)| 6.8 | 0.047 | VI SAN JACINTO-COYOTE CREEK | 49.4( 79.5)| 6.6 | 0.026 | V SAN JACINTO-ANZA | 51.0( 82.0)| 7.2 | 0.041 | V SAN JACINTO - BORREGO | 51.4( 82.7)| 6.6 | 0.024 | V ELSINORE (GLEN IVY) | 60.4( 97.2)| 6.8 | 0.022 | IV SUPERSTITION MTN. (San Jacinto) | 61.4( 98.8)| 6.6 | 0.018 | IV ******************************************************************************* -END OF SEARCH- 12 FAULTS FOUND WITHIN THE SPECIFIED SEARCH RADIUS. THE ROSE CANYON FAULT IS CLOSEST TO THE SITE. IT IS ABOUT 14.0 MILES (22.5 km) AWAY. LARGEST MAXIMUM-EARTHQUAKE SITE ACCELERATION: 0.2145 g

Page 4

SLOPE STABILITY CALCULATIONS

Exisitng Slope - Static Prospect Ave OC N:\PROJECTS\_AV\I300\I-391T~1.OC\ANALYSIS\STED\I391-1.PL2 Run By: Username 1/27/2006 3:29PM 470 # FS Soil Soil Total Saturated Cohesion Friction Piez. Load Value Init Points: 15. to 50. a 1.66 Desc. Type Unit Wt. Unit Wt. Intercept Angle Surface L1 8000 psf Term Limits: 62. to 90. b 1.68 No. (pcf) (pcf) (psf) (deg) No. L2 240 psf c 1.69 Fill 1 120.0 120.0 0.0 34.0 0 d 1.72 Sand 2 130.0 130.0 260.0 36.0 0 e 1.73 Bedrock 3 130.0 130.0 260.0 36.0 0 f 1.73 g 1.74 h 1.74 i 1.74 j 1.76 450

a j ih f e g dc b L2 1 430 1 2 2

2 2 2 L1 2 2 3 3 3 410

390 0 20 40 60 80 100 PCSTABL5M/si FSmin=1.66 Safety Factors Are Calculated By The Modified Bishop Method 10' High Cut Into Slope Below Footing Prospect Ave OC N:\PROJECTS\_AV\I300\I-391T~1.OC\ANALYSIS\STED\I391-2.PL2 Run By: Username 1/27/2006 12:12PM 470 # FS Soil Soil Total Saturated Cohesion Friction Piez. Load Value Init Points: 46. to 46.02 a 1.07 Desc. Type Unit Wt. Unit Wt. Intercept Angle Surface L1 8000 psf Term Limits: 62. to 99. b 1.09 No. (pcf) (pcf) (psf) (deg) No. L2 240 psf c 1.12 Fill 1 120.0 120.0 0.0 34.0 0 d 1.15 Sand 2 130.0 130.0 260.0 36.0 0 e 1.15 Bedrock 3 130.0 130.0 260.0 36.0 0 f 1.20 g 1.21 h 1.21 i 1.22 j 1.25 450

a hi j e g f b c d L2 1 430 1 2 2

2 2 2 L1 2 2

3 3 3 410 3

390 0 20 40 60 80 100 PCSTABL5M/si FSmin=1.07 Safety Factors Are Calculated By The Modified Bishop Method 6' High Cut Into Slope Below Footing Prospect Ave OC N:\PROJECTS\_AV\I300\I-391T~1.OC\ANALYSIS\STED\I391-2A.PL2 Run By: Username 1/27/2006 12:17PM 470 # FS Soil Soil Total Saturated Cohesion Friction Piez. Load Value Init Points: 46.01 to 46.02 a 1.50 Desc. Type Unit Wt. Unit Wt. Intercept Angle Surface L1 8000 psf Term Limits: 62. to 99. b 1.55 No. (pcf) (pcf) (psf) (deg) No. L2 240 psf c 1.55 Fill 1 120.0 120.0 0.0 34.0 0 d 1.56 Sand 2 130.0 130.0 260.0 36.0 0 e 1.56 Bedrock 3 130.0 130.0 260.0 36.0 0 f 1.56 g 1.57 h 1.61 i 1.65 j 1.66 450

a hi j eg f cb d L2 1 430 1 2 2

2 2 2 L1 2 2 3 3 3 3 410

390 0 20 40 60 80 100 PCSTABL5M/si FSmin=1.50 Safety Factors Are Calculated By The Modified Bishop Method 6' High Cut Into Slope Below Footing Prospect Ave OC N:\PROJECTS\_AV\I300\I-391T~1.OC\ANALYSIS\STED\I391-2A2.PL2 Run By: Username 1/27/2006 3:40PM 470 # FS Soil Soil Total Saturated Cohesion Friction Piez. Load Value Init Points: 46.01 to 46.01 a 1.69 Desc. Type Unit Wt. Unit Wt. Intercept Angle Surface L1 8000 psf Term Limits: 47. to 56. b 1.71 No. (pcf) (pcf) (psf) (deg) No. L2 240 psf c 1.72 Fill 1 120.0 120.0 0.0 34.0 0 d 1.75 Sand 2 130.0 130.0 260.0 36.0 0 e 1.75 Bedrock 3 130.0 130.0 260.0 36.0 0 f 1.76 g 1.76 h 1.76 i 1.77 j 1.77 450

L2 1 430 1 2 a 2 j i hgfd e b 2 c 2 2 L1 2 2 3 3 3 3 410

390 0 20 40 60 80 100 PCSTABL5M/si FSmin=1.69 Safety Factors Are Calculated By The Modified Bishop Method 10' High Cut Below Ftg upper tie only Prospect Ave OC N:\PROJECTS\_AV\I300\I-391T~1.OC\ANALYSIS\STED\I391-2T.PL2 Run By: Username 2/8/2006 6:55PM 470 # FS Soil Soil Total Saturated Cohesion Friction Piez. Load Value Init Points: 46. to 46.02 a 1.38 Desc. Type Unit Wt. Unit Wt. Intercept Angle Surface L1 8000 psf Term Limits: 62. to 99. b 1.46 No. (pcf) (pcf) (psf) (deg) No. L2 240 psf c 1.52 Fill 1 120.0 120.0 0.0 34.0 0 d 1.54 Sand 2 130.0 130.0 260.0 36.0 0 e 1.54 Bedrock 3 130.0 130.0 260.0 36.0 0 f 1.57 g 1.58 h 1.59 i 1.63 j 1.65 450

a h j i e f g b d c L2 1 430 1 2 2

2 2 2 L1 2 2

3 3 T1@15ft 3 410 3

390 0 20 40 60 80 100 PCSTABL5M/si FSmin=1.38 Safety Factors Are Calculated By The Modified Bishop Method 10' High wall finished configuration Prospect Ave OC N:\PROJECTS\_AV\I300\I-391T~1.OC\ANALYSIS\STED\I391-2TA.PL2 Run By: Username 2/8/2006 7:00PM 470 # FS Soil Soil Total Saturated Cohesion Friction Piez. Load Value Init Points: 46. to 46. a 1.91 Desc. Type Unit Wt. Unit Wt. Intercept Angle Surface L1 8000 psf Term Limits: 62. to 85. b 1.93 No. (pcf) (pcf) (psf) (deg) No. L2 240 psf c 1.93 Fill 1 120.0 120.0 0.0 34.0 0 d 1.93 Sand 2 130.0 130.0 260.0 36.0 0 e 1.95 Bedrock 3 130.0 130.0 260.0 36.0 0 f 1.96 g 1.98 h 1.99 i 1.99 j 2.00 450

a i j h e f g cb d L2 1 430 1 2 2

2 2 2 L1 2 2

3 3 3 T1@15ft 410 3

390 0 20 40 60 80 100 PCSTABL5M/si FSmin=1.91 Safety Factors Are Calculated By The Modified Bishop Method 10' High wall finished configuration Prospect Ave OC N:\PROJECTS\_AV\I300\I-391T~1.OC\ANALYSIS\STED\I3912TAS.PL2 Run By: Username 2/8/2006 8:37PM 470 # FS Soil Soil Total Saturated Cohesion Friction Piez. Load Value Init Points: 46. to 46. a 1.79 Desc. Type Unit Wt. Unit Wt. Intercept Angle Surface L1 8000 psf Term Limits: 62. to 85. b 1.81 No. (pcf) (pcf) (psf) (deg) No. L2 240 psf c 1.81 Fill 1 120.0 120.0 0.0 34.0 0 Horiz Eqk 0.100 g< d 1.82 Sand 2 130.0 130.0 260.0 36.0 0 e 1.83 Bedrock 3 130.0 130.0 260.0 36.0 0 f 1.84 g 1.84 h 1.86 i 1.86 j 1.86 450

a h ji e f g dc b L2 1 430 1 2 2

2 2 2 L1 2 2

3 3 3 T1@15ft 410 3

390 0 20 40 60 80 100 PCSTABL5M/si FSmin=1.79 Safety Factors Are Calculated By The Modified Bishop Method