revised district preliminary geotechnical report i-605 ... studies...i-605/katella avenue...

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17800 Newhope Street, Suite B, Fountain Valley, CA 92708 Tel: (714) 751-3826 Fax: (714) 751-3928 July 28, 2017 EMI Project No. 17-120 Michael Baker International 5 Hutton Centre Drive, Suite 500 Santa Ana, CA 92707 Attention: Mr. Bo Burick, PE Subject: Revised District Preliminary Geotechnical Report I-605/Katella Avenue Interchange Improvements Project Orange County, California 12-Ora-605, PM 1.1/1.6 EA No. 12-0K8700, Caltrans Project No. 1200020230 Dear Mr. Burick: Attached is our District Preliminary Geotechnical Report (DPGR) for the Interstate 605 (I-605)/Katella Avenue Interchange Improvements Project in the County of Orange, California. This report is prepared to support the Project Approval and Environmental Document (PA-ED) phase of the project. A previous version of this DPGR, dated June 7, 2017, was submitted to Caltrans for review. Caltrans provided their comments on July 19, 2017. Caltrans review comments and EMI responses are included in Appendix C. The responses to these review comments have been incorporated into this revised report. The recommendations and conclusions provided in this report are based on available subsurface soil information. These conclusions and recommendations are considered preliminary and should be verified in future by conducting additional site-specific geotechnical field investigations, laboratory testing, and engineering analyses. We appreciate the opportunity to provide geotechnical services for this project. If you have any questions please do not hesitate to contact us. Sincerely, EARTH MECHANICS, INC. (Alahesh) A. Thurairajah, PE 81439 Michael Hoshiyama, CEG 2599 Project Engineer Lino Cheang, GE 2345 Project Manager Project Geologist NO. C81439 EXP. 9-30-2017

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17800 Newhope Street, Suite B, Fountain Valley, CA 92708 Tel: (714) 751-3826 Fax: (714) 751-3928

July 28, 2017

EMI Project No. 17-120 Michael Baker International 5 Hutton Centre Drive, Suite 500 Santa Ana, CA 92707

Attention: Mr. Bo Burick, PE

Subject: Revised District Preliminary Geotechnical Report I-605/Katella Avenue Interchange Improvements Project Orange County, California 12-Ora-605, PM 1.1/1.6 EA No. 12-0K8700, Caltrans Project No. 1200020230

Dear Mr. Burick:

Attached is our District Preliminary Geotechnical Report (DPGR) for the Interstate 605 (I-605)/Katella Avenue Interchange Improvements Project in the County of Orange, California. This report is prepared to support the Project Approval and Environmental Document (PA-ED) phase of the project.

A previous version of this DPGR, dated June 7, 2017, was submitted to Caltrans for review. Caltrans provided their comments on July 19, 2017. Caltrans review comments and EMI responses are included in Appendix C. The responses to these review comments have been incorporated into this revised report.

The recommendations and conclusions provided in this report are based on available subsurface soil information. These conclusions and recommendations are considered preliminary and should be verified in future by conducting additional site-specific geotechnical field investigations, laboratory testing, and engineering analyses.

We appreciate the opportunity to provide geotechnical services for this project. If you have any questions please do not hesitate to contact us.

Sincerely, EARTH MECHANICS, INC. (Alahesh) A. Thurairajah, PE 81439

Michael Hoshiyama, CEG 2599

Project Engineer Lino Cheang, GE 2345 Project Manager

Project Geologist

NO. C81439EXP. 9-30-2017

DISTRICT PRELIMINARY GEOTECHNICAL REPORT I-605/KATELLA AVENUE INTERCHANGE IMPROVEMENTS PROJECT

ORANGE COUNTY, CALIFORNIA 12-Ora-605, PM 1.1/1.6

EA No. 12-0K8700 CALTRANS PROJECT No. 1200020230

Prepared for:

Michael Baker International 5 Hutton Centre Drive, Suite 500

Santa Ana, CA 92707

Prepared by:

Earth Mechanics, Inc. 17800 Newhope Street, Suite B

Fountain Valley, California 92708

EMI Project No. 17-120

July 28, 2017

TABLE OF CONTENTS Section Page

1.0 INTRODUCTION.............................................................................................................. 1

2.0 EXISTING FACILITIES .................................................................................................. 1

2.1 Interstate 605 .................................................................................................................... 1 2.2 Katella Avenue ................................................................................................................. 3

3.0 PROPOSED PROJECT ALTERNATIVES ................................................................... 3

4.0 SITE GEOLOGY ............................................................................................................... 4

4.1 Physiography, Topography and Drainage ........................................................................ 4 4.2 Stratigraphy ...................................................................................................................... 4 4.3 Geologic Structure............................................................................................................ 5 4.4 Geologic Hazards ............................................................................................................. 5

5.0 SUBSURFACE SOIL AND GROUNDWATER CONDITIONS .................................. 6

5.1 Subsurface Soil Conditions .............................................................................................. 6 5.2 Groundwater Conditions .................................................................................................. 7

6.0 FAULTING AND SEISMICITY ...................................................................................... 8

7.0 MATERIAL SOURCES .................................................................................................. 10

8.0 MATERIAL DISPOSAL ................................................................................................ 10

9.0 CONCLUSIONS AND RECOMMENDATIONS ......................................................... 10

9.1 Earthwork ....................................................................................................................... 10 9.2 Soil Expansion Potential ................................................................................................ 10 9.3 Soil Erosion Potential ..................................................................................................... 11 9.4 Liquefaction Potential and Seismically-Induced Settlement ......................................... 11 9.5 Embankment Settlement ................................................................................................ 11 9.6 Stability of Embankment Slopes .................................................................................... 12 9.7 Cut Slopes ...................................................................................................................... 12 9.8 Hazardous Waste Considerations ................................................................................... 13 9.9 Future Geotechnical Investigations ................................................................................ 13

10.0 LIMITATIONS ................................................................................................................ 13

11.0 REFERENCES ................................................................................................................. 14

TABLES

Page

Table 1. Idealized Soil Profile ........................................................................................................ 6 Table 2. Fault Data .......................................................................................................................... 8 Table 3. Key Parameters for Determining Preliminary PGA ......................................................... 8 Table 4. Major Embankments and Estimated Settlement ............................................................. 12

FIGURES Page

Figure 1. Site Location Map ........................................................................................................... 2 Figure 2. Caltrans Fault Map .......................................................................................................... 9

APPENDICES

Appendix A. Available LOTB Sheets Appendix B. Available Laboratory Test Results Appendix C. Responses to Review Comments

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1.0 INTRODUCTION

This District Preliminary Geotechnical Report (DPGR) has been prepared to provide the preliminary geotechnical information for the purpose of preparing engineering plans and cost estimates for the Interstate 605 (I-605)/Katella Avenue Interchange Improvements Project. The preliminary geotechnical information provided in this report are based on subsurface information contained on the Log-of-Test-Borings (LOTB) sheets included in Appendix A. Additional site-specific geotechnical investigation will be performed during the final design phase; therefore, the following preliminary geotechnical information require verification when additional site-specific information becomes available. Pavement recommendations and soils corrosion are addressed in the Preliminary Materials Report (EMI, 2017a).

The Orange County Transportation Authority (OCTA), in cooperation with the California Department of Transportation (Caltrans) District 12 and the City of Los Alamitos, proposes to improve the I-605/Katella Avenue interchange and Katella Avenue between Coyote Creek Channel and Civic Center Drive. The I-605/Katella Avenue interchange is located on I-605 between Interstate 405 (I-405) and Spring Street, within the City of Los Alamitos in Orange County. The project location is shown in Figure 1.

2.0 EXISTING FACILITIES

2.1 Interstate 605

I-605 is a major north-south transportation route within Orange and Los Angeles Counties. It is an integral part of the freeway network for the Southern California metropolitan area, connecting I-405 at its southerly terminus to Interstate 210 (I-210) at its northerly terminus. In the project area, I-605 has four general purpose lanes and one high occupancy vehicle (HOV) lane in each direction. A concrete barrier in the median separates the two directions of travel. From the I-405 interchange to Katella Avenue, there is an auxiliary lane in each direction and a sound barrier along the NB right shoulder.

I-605/Katella Avenue interchange was constructed in the 1960’s in conjunction with the I-605 freeway improvements. The existing interchange configuration is a mix of loop and direct ramp configurations that reflect the constraints of the Coyote Creek Channel. It is a modified full cloverleaf configuration with loop ramps in all quadrants except the southeast quadrant which contains a direct exit ramp from NB I-605. The existing bridges over Katella Avenue are four-span reinforced concrete box girder bridges supported on concrete pile foundations. A direct exit ramp from SB I-605 is located to the west of the Coyote Creek Channel, outside the project limits. All ramp termini within the project limits incorporate free-right movements.

Earth Mechanics, Inc.Geotechnical and Earthquake Engineering

Project No. 17-120 Date: June 2017SITE LOCATION MAP

Figure 1

I-605/KATELLA AVENUE INTERCHANGE

Project Site

N

L.Cheang
Typewritten Text
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2.2 Katella Avenue

Katella Avenue is a key regional arterial in the east-west direction across Orange County. It provides regional access from Los Alamitos to I-605 to the west, where it continues as Willow Street in the City of Long Beach. To the east, it connects Los Alamitos to the Cities of Cypress, Stanton, Anaheim, and Garden Grove. It is identified as an 8-Lane Smart Street on the Orange County Master Plan of Arterial Highways and as a Smart Street in the City of Los Alamitos General Plan Circulation Element. Additionally, it is identified as a Truck Route in the City of Los Alamitos General Plan.

At the easterly limits of the project area, Katella Avenue has four travel lanes in each direction. Approaching the interchange in the westbound (WB) direction, the No. 4 lane is dropped as a right turn lane onto the NB I-605 on-ramp. Continuing west, the No. 1 lane is dropped through a left-hand merge, leaving two through lanes continuing on Willow Street. An auxiliary lane is provided in the WB direction between the NB I-605 loop exit ramp and the SB loop entrance ramp. From the west, two travel lanes approach the interchange in the eastbound (EB) direction. Through the interchange, the single-lane SB loop exit ramp joins Katella Avenue as the No. 3 lane and immediately merges with the No. 2 lane. Continuing east, two lanes are added to Katella Avenue at the NB I-605 exit ramp, providing four travel lanes to the east. Sidewalk is provided on both sides of Katella Avenue through the interchange; however both facilities terminate on the west side of the interchange before reaching the sidewalks on the Coyote Creek Channel bridge structure. Dedicated bike lanes are not provided through the interchange.

3.0 PROPOSED PROJECT ALTERNATIVES

Three alternatives, including the No Build Alternative, are being analyzed as a part of this project. These alternatives are described below.

Alternative 1: Under this alternative, there would be no reconstruction or improvements to the existing I-605/Katella Avenue interchange other than routine roadway maintenance.

Alternative 2: This alternative proposes to modify interchange ramps and lane configurations, without altering the existing bridge structures. The existing I‐605 mainline will not be modified, with the exception of the northbound No. 4 lane at the northbound exit ramp. The lane will be restriped to provide a through lane/ramp exit option to accommodate a proposed 2nd lane on the exit ramp. Portions of the existing interchange ramps will be widened or reconstructed. A new retaining wall will be constructed to accommodate modifications to the northbound direct entrance ramp. The retaining wall pertinent data and preliminary foundation recommendations are provided in the Structure Preliminary Geotechnical Report (EMI, 2017b). Katella Avenue will be widened and lane geometries will be modified to provide standard lanes and shoulders through the interchange and to tie in with proposed ramp improvements.

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Alternative 3: This alternative proposes to modify interchange ramps and lane configurations, without altering the existing bridge structures. The existing I‐605 mainline will not be modified, with the exception of the northbound No. 4 lane at the northbound exit ramp. The lane will be restriped to provide a through lane/ramp exit option to accommodate a proposed 2nd lane on the exit ramp. Portions of the existing interchange ramps will be widened or reconstructed. The existing southbound loop entrance ramp will be removed. Three new retaining walls will be constructed to accommodate modifications to the northbound and southbound direct entrance ramps. The retaining wall pertinent data and preliminary foundation recommendations are provided in the Structure Preliminary Geotechnical Report (EMI, 2017b). Katella Avenue will be widened and lane geometries will be modified to provide standard lanes and shoulders through the interchange and to tie in with proposed ramp improvements.

4.0 SITE GEOLOGY

4.1 Physiography, Topography and Drainage

Physiography and Topography. The site is in the Long Beach/Seal Beach/Los Alamitos area of the Los Angeles Basin between the western Transverse Ranges on the north and the Peninsular Ranges physiographic provinces. The Los Angeles Basin is a low-elevation coastal plain surrounded by mountains. The mountains include the Santa Monica Mountains on the north, the Repetto Hills, Puente Hills, and the Santa Ana Mountains on the east, and the San Joaquin Hills on the south. The floor of the Los Angeles Basin slopes gently southerly and westerly from surrounding hills and mountains, except where it is interrupted by a northwest-southeast trending alignment of hills and mesas extending from the Beverly Hills area in the north to Newport Bay on the south. This alignment of hills is referred to as the Newport-Inglewood Structural Zone (NISZ) and effectively divides the Los Angeles Basin into the Downey-Tustin plain on the northeast and the Torrance Plain-Long Beach Plain on the southwest. The site area is flat with elevations in the 20 feet range. I-605 at this location is on a fill embankment with elevations in the 40 feet range.

Drainage. The San Gabriel River, less than one-half mile to the west, carries surface flow from the San Gabriel Mountains to the north. Locally the concrete lined Coyote Creek flows proximal to the project site.

4.2 Stratigraphy

Regional geological studies indicate that the surficial materials in the region surrounding the site consist of non-indurated, Quaternary-age, alluvial sediments. The Quaternary sediments are Holocene-age alluvium, late Pleistocene-age alluvial deposits of the Lakewood Formation, and early Pleistocene marine deposits of the San Pedro Formation. These deposits overlie Pliocene-age deposits of the Pico Formation and deeper Miocene-age sedimentary rock formations. Crystalline basement rock is at about 22,000 feet depth (Yerkes et al., 1965).

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The upper Holocene-age deposits are primarily fine grained materials of clay/silt/fine sand. These deposits have organic material (primarily plant material) indicative of poorly drained marshy conditions. The deeper Holocene deposits commonly have beds of coarse sand with scattered gravel. These are indicative of active stream deposition and document a time when streams meandered back and forth across the area. The Holocene deposits are on the order of 50 to 60 feet thick in the site region (Zielbauer et al., 1961; Department of Water Resources, 1968).

The Lakewood Formation consists of shallow marine, coastal, and non-marine deposits ranging in thickness from an erosional edge to a maximum thickness of about 400 feet. The beds are folded upward and the upper part of the formation is exposed within the hills and mesas of the Newport-Inglewood Structural Zone. Inland, the Lakewood dips below the Holocene deposits and is not exposed.

The underlying San Pedro Formation is a marine deposit at depths ranging from about 70 feet below sea level in the gaps to about 420 feet below sea level farther inland. The formation is more than a thousand feet thick.

The Lakewood and San Pedro formations are quite similar and can be differentiated with certainty only by fossils. The San Pedro is generally gray in color and the Lakewood is commonly oxidized to brownish and yellowish-brown colors.

4.3 Geologic Structure

The Los Angeles Basin is a large northwesterly trending structural downwarp bounded by faults. The principal downwarp structure is the Paramount Syncline which trends northwest-southeast between the Newport-Inglewood Structural zone on the southwest and the Puente Hills fault system (Los Angeles, Santa Fe Springs, and Coyote Hills faults) on the northeast. Other significant faults in the region are the Palos Verdes fault in the offshore area, the Santa Monica-Hollywood fault system on the north, the Whittier fault to the east, and several subsurface blind faults (e.g. Upper Elysian Park fault and Puente Hills fault system).

4.4 Geologic Hazards

Geological hazards relevant to the project area include earthquake shaking and localized soil liquefaction.

There are no known active surface faults within the project limits so the potential for ground rupture is considered low. The nearest active or potentially active fault is located approximately 3.2 miles from the project site, as a result moderate to intense ground shaking should be anticipated within the project area in the event of an earthquake.

Some alluvial sediments within the project area are susceptible to liquefaction. The potential for liquefaction is discussed in more detail in Section 9.4.

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5.0 SUBSURFACE SOIL AND GROUNDWATER CONDITIONS

5.1 Subsurface Soil Conditions

The As-built LOTB sheet of the Katella Avenue UC provided in Appendix A was reviewed. According to this as-built LOTB sheet, two rotary-wash borings (B-2 and B-4) and four penetration borings (B-1, B-3, B-5, and B-6) were performed in September 1962, and two penetration borings (B-7 and B-8) were performed in December 1962. Top-of-hole elevation at the time of the investigation was about +19 feet. The depth of the boreholes varied between 60 and 80 feet, and the deepest boring (B-6) advanced to about elevation -61 feet.

In August 2009, EMI prepared a Final Foundation Report for Overhead Sign Structures as part of the Interstate 405 (I-405)/I-605 HOV Connector Segment of the West County Connector Project (EMI, 2009). Relevant subsurface data was extracted from this report and consisted of two hollow-stem auger borings (A 09 071 and A 09 072) and two Cone Penetration Test (CPT) soundings (CPT 09 071 and CPT 09 072) performed in January 2009; these borings and CPTs were located in the vicinity of the I-605/Katella Avenue Interchange. Pertinent LOTB sheets and laboratory tests results are provided in Appendix A and Appendix B, respectively. Top-of-hole elevation at the time of the investigation varied between +28 and +49 feet. The depth of the boreholes varied between 46 and 61 feet, and the depth of the CPT soundings varied between 12 and 82 feet. The deepest boring (A 09 071) and CPT sounding (CPT 09 072) were advanced to about elevation -33 feet.

The available subsurface information indicates that site soils are fill underlain by alluvial deposits, and composed of alternating layers of clay, silt and sand. Consistency of the soils is increasing with depth, typically from very soft to very stiff for clayey and silty soils and from medium dense to very dense for sandy soils. The idealized soil profile is presented in Table 1.

Table 1. Idealized Soil Profile

Approximate Elevation (feet) Predominant Soil Type

+43 to +20 Medium Stiff to Stiff Clay and Silt +20 to -4 Very soft to Soft Silt -4 to -19 Medium Dense to Dense Sand and Silty Sand

-19 to -34 Stiff to Very Stiff Clay and Silt -34 to -56 Very Dense Silty Sand, Sand, Sandy Gravel

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5.2 Groundwater Conditions

According to the Katella Avenue UC as-built LOTB sheet, groundwater was encountered near El. -17 feet (about 57 feet below the I-605 freeway grade) during drilling in September and December 1962. Groundwater was encountered between elevations +2 and +7 feet (about 26 and 36 feet below the I-605 freeway surface) during EMI’s field investigations for the nearby sign structures in January 2009. The project site is immediately adjacent to Coyote Creek Channel and about 1/2 mile away from the San Gabriel River. Therefore, groundwater at the project site is sensitive to the conditions of these two nearby large drainage facilities.

Based on California Geological Survey (CGS, 1998), the highest historical groundwater depth is about 20 feet. The groundwater depth published by CGS is slightly higher than the groundwater depth presented in the 2009 LOTB sheets. This is reasonable because the CGS data are historical highs. The California Department of Water Resources Water Data Library was reviewed for groundwater measurements in wells located near the project site. Based on the three wells in a 1-mile radius from the center of the I-605/Katella Avenue Interchange, the highest groundwater level varies between elevations -20 and -24 feet (about 23 to 42 feet below ground surface) between years 1969 and 1993. Ground surface elevations at these wells were between 0 and 18 feet.

Based on the above data, preliminary design groundwater table was placed at 25 feet below the I-605 freeway grade for preliminary liquefaction analysis. Groundwater elevation used for final design will be determined when site-specific field investigation is completed during the PS&E phase.

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6.0 FAULTING AND SEISMICITY

The project site is located in seismically active southern California and is subjected to shaking from both local and distant earthquakes. The nearest substantial local sources of earthquakes are provided in Table 2 along with their fault ID, fault type and their maximum earthquake magnitude, slip rate, and age according to the Caltrans Fault Database (Merriam, 2012). The site to fault distances were determined using Caltrans ARS Online V2.3.09 (2017). The substantial local sources of earthquake faults provided in Table 2 are also shown in Figure 2.

Table 2. Fault Data

Fault Fault ID

Fault Type

Maximum Earthquake Magnitude

Slip Rate (mm/yr) Age

Approx. Distance

from Site to Fault (miles)

Newport Inglewood Fault Zone (S. Los Angeles Basin Section – Southern)

366 SS 7.2 1.0 Holocene 3.2

Anaheim 363 R 6.4 0.1 Holocene 4.8 Compton 367 R 6.9 0.9 Holocene 5.1 Puente Hills (Coyote Hills) 361 R 6.8 0.7 Holocene 6.8 Newport Inglewood Fault Zone (N. Los Angeles Basin Section)

342 SS 7.2 1.0 Holocene 10.0

Note: SS = Strike Slip, R = Reverse.

The preliminary design PGA for the project site was determined using the Caltrans ARS Online website and the shear wave velocity (Vs30) estimated from the available LOTB sheets. The key parameters for determining the preliminary PGA are listed in Table 3.

Table 3. Key Parameters for Determining Preliminary PGA

Site Coordinates Latitude = 33.8031 degrees Longitude = -118.0818 degrees

Shear Wave Velocity, Vs30 869 feet/sec (265 m/sec)

The deterministic response spectrum of Compton Fault controls the preliminary design PGA, and the PGA is 0.569g. The preliminary design PGA estimate will be updated during PS&E, following the field investigation based on a Vs30 estimated from site specific borings.

Ground Rupture: No major faults traverse through the project site. The California Division of Mines and Geology has not identified Alquist-Priolo Fault Zones through the site. Therefore, the risk of ground surface rupture and related hazards at the project site are expected to be low. According to Caltrans Memo To Designers 20-10 (Caltrans, 2013), since the project site does not fall within an Alquist-Priolo Earthquakes Fault Zone or within 1,000 feet of an unzoned fault that is Holocene or younger in age, further fault studies will not be needed.

Project Site

Earth Mechanics, Inc.Geotechnical and Earthquake Engineering

I-605/Katella Avenue Interchange

Project No. 17-120 Date: June 2017

Caltrans Fault Map

Figure 2

Note: Substantial local sources of earthquake faults are identified.

L.Cheang
Typewritten Text
9

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7.0 MATERIAL SOURCES

Numerous commercial suppliers for sand, gravel, aggregate base, and concrete are located in Los Angeles and Orange counties, which will be identified during the PS&E phase of the project. Pulverizing existing pavement might be performed during construction. Pulverized AC and Portland cement concrete can be used as aggregate base assuming the pulverized material is processed and meets the quality requirements of Aggregate Base (AB) specified in the Caltrans Standard Specifications (2015a). Caltrans must approve the use of pulverized material for AB.

8.0 MATERIAL DISPOSAL

Based on the preliminary plans, import material will be required to achieve proposed grades. Therefore, off-site disposal of existing on-site soils is not anticipated.

9.0 CONCLUSIONS AND RECOMMENDATIONS

9.1 Earthwork

Earthwork should be performed in accordance with Caltrans Standard Specifications, Section 19 (Caltrans, 2015a). In areas where compacted fill will be placed, complete removal of compressible surficial materials including topsoil, loose or soft alluvium or fill soil, dry or saturated soil, or otherwise unsuitable material is required prior to fill placement. A minimum overexcavation and recompaction of 24 inches is recommended within all areas to receive compacted fill, and the overexcavation depth is measured from the existing grade. The overexcavation should extend horizontally a minimum distance of 24 inches from edges of new fills. In cut areas where the difference between the finished and existing grade is 2 feet or less, the minimum overexcavation and recompaction depth is 12 inches below the finish grade. In cut areas where the difference between the finished grade and existing grade is greater than 2 feet, overexcavation is not required. Unless specified on the contract plans or specifications, the excavated soils (in both fill and cut areas) may be reused as compacted fill in general fill areas. Fill placed behind retaining walls, beneath spread footings, should be Caltrans Structure Backfill. In addition, select fill material may be required directly beneath proposed pavement sections. Actual depths and extent of remedial removals should be determined in the field by qualified geotechnical personnel during earthwork activities.

All overexcavations should be observed by qualified geotechnical personnel to verify that firm and unyielding bottoms are exposed. Overexcavated areas should be cleaned of loose soils and debris and should be observed to be firm and unyielding before receiving fill.

Fills placed against sloping ground shall be keyed and benched into the sloping ground and placed as specified in Section 19-6 of the Caltrans Standard Specifications (2015a).

9.2 Soil Expansion Potential

Based on the available LOTB sheets, shallow on-site soils within the project limits are predominately clay and silt. The expansion potential of these clayey and silty soils is considered to be moderate to high. Soil expansion potential should be evaluated during PS&E using the site-specific borings and soil laboratory tests.

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9.3 Soil Erosion Potential

Based on the available LOTB sheets, surficial soils within the project limits are mostly clayey and silty soils. These clayey and silty surficial soils are expected to expand when wet, and crack upon drying. Cracking allows infiltration of water from storms and irrigation, ultimately causing loosening of the surficial soils. This results in increase of the soil erodibility. The embankment side slopes within the project limits were graded mostly at an inclination of 2H:1V and are covered with moderate vegetation. Erosion of the existing slope faces was observed to be minimal.

For the proposed project, prompt revegetation of graded slopes should be performed to minimize erosion, and runoff should be diverted from the slope face using earthen berms and/or concrete swales at the top of slope.

9.4 Liquefaction Potential and Seismically-Induced Settlement

Liquefaction Potential: Based on the Seismic Hazard Maps of the Los Alamitos Quadrangle (CGS, 1986 and 1999), site soils are susceptible to liquefaction. Based on our experience, there is uncertainty in these published CGS Seismic Hazard Maps because these maps were developed based on limited subsurface data and analysis.

Preliminary liquefaction analyses were performed using the procedures outlined by Seed et al. (1983) and updated by NCEER (1997) and Youd et al. (2001), and the Standard Penetration Test (SPT) blowcounts and soil descriptions shown on the attached LOTB sheets. Results of the analysis show the presence of potentially liquefiable soil pockets; however, these liquefiable soil pockets are localized and not continuous across the project site. Soil liquefaction potential will be confirmed using additional site-specific exploratory boreholes to be performed during the PS&E phase of the project.

Seismically-Induced Settlement: Based on our preliminary calculations, the maximum liquefaction-induced settlement is expected to be less than 2 inches. However, these findings will need to be confirmed using site-specific subsurface exploration to be performed during the PS&E phase of the project.

9.5 Embankment Settlement

Based on the available subsurface soil and groundwater conditions, the project site is anticipated to experience majority of the settlement from consolidation (long-term) settlement. Based on the preliminary cross sections provided by the civil designers, the majority of fill placement for embankment construction is expected to be minor. The major fill embankments are presented in Table 4. For major embankment fills, ground settlements were estimated based on the available subsurface information and proposed maximum height of fill. The estimated ground settlements are shown in Table 4. These settlement magnitudes will need to be confirmed using site-specific boreholes and laboratory test results during PS&E.

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Table 4. Major Embankments and Estimated Settlement

Location Alternative Approx. Maximum Height of Fill

Estimated Settlement (inches)

SB Loop On-Ramp 2 11 2.4 SB Loop Off-Ramp 2 and 3 8 1.8 NB Loop Off-Ramp 2 and 3 7 1.7 NB Direct On-Ramp 2 and 3 7 1.7 SB Direct On-Ramp 2 7 1.7 SB Direct On-Ramp 3 4 1.1

Katella Avenue (North Side) 2 and 3 10 2.2 Katella Avenue (South Side) 3 7 1.7

9.6 Stability of Embankment Slopes

Per Caltrans HDM Topic 304 (2015b), side slopes should be constructed (where possible) no steeper than 4H:1V. A design exception will be required for side slopes with gradients steeper than 4H:1V. Slopes steeper than 2H:1V should be avoided. Otherwise, geogrids are recommended for slopes steeper than 2H:1V.

The proposed fill embankments are expected to be globally stable for a slope gradient of 2H:1V or flatter. Fill slopes with a gradient of 2H:1V or flatter are also expected to be surficially stable. For fill slopes steeper than 2H:1V, slope paving will be required and therefore surficial stability is not a design concern. In all cases, drainage control, proper maintenance, and erosion protection in accordance with Section 21 of Caltrans Standard Specifications (2015a) are recommended.

Stability of fill embankments should be evaluated during PS&E using subsurface information obtained from site-specific boreholes.

9.7 Cut Slopes

Based on the preliminary cross sections provided by the civil designers, few relatively minor cuts (about 5 feet or less) are required to accommodate the proposed roadway improvements.

Cut slopes with a 2H:1V or flatter gradient are expected to be globally stable. For cut slopes with a gradient of 2H:1V or flatter, surficial stability is also not expected to be a design concern. If slope paving is proposed for cut slopes with a gradient of 1.5H:1V, then surficial stability is also not a design concern. In all cases, drainage control, proper maintenance, and erosion protection in accordance with Section 21 of Caltrans Standard Specifications (2015a) are recommended.

Cut slope stability should be evaluated during the final design phase using subsurface information obtained from site-specific boreholes.

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9.8 Hazardous Waste Considerations

If for any reason hazardous or toxic materials are believed to exist within the project area, an environmental specialist should be consulted. The presence of aerially-deposited lead, as well as other hazardous and toxic materials, should be investigated during the PS&E phase.

9.9 Future Geotechnical Investigations

EMI recommends a site-specific geotechnical field investigation for the proposed project improvements, during the final design phase of the project. The field investigation will be conducted in an effort to determine the feasibility and potential construction issues that could be encountered for the proposed project improvements. Based on the preliminary plans, EMI recommends the following geotechnical field investigation program;

Ramp Improvements. EMI recommends drilling two borings at each ramp in addition to the retaining wall borings; the termination depth of these borings varies from 5 to 30 feet. The retaining wall field exploration program is provided in the Structure Preliminary Geotechnical Report for Retaining Walls (EMI, 2017b).

Katella Avenue Improvements. EMI recommends drilling no more than five shallow borings (5-foot depth) to collect subsurface information for Katella Avenue widening.

Samples recovered during the field investigation will be transported to the laboratory for testing. All of the soil samples will be visually classified. Additional samples will be selected for in-situ moisture content/density tests, sieve analysis, #200 wash, Atterberg limits, expansion potential, sand equivalents, corrosivity, direct shear, consolidation, UU triaxial test, R-value and maximum density and optimum moisture content. Other laboratory tests may be required depending upon the nature of the soils encountered during the investigation.

10.0 LIMITATIONS

This District Preliminary Geotechnical Report is intended for use by Michael Baker International, OCTA, and Caltrans for the I-605/Katella Avenue Interchange Improvements Project. This report is based on the project as described herein and the available as-built subsurface information. The earth materials and subsurface conditions described in the as-built exploratory borings are presumed to be representative of the project site; however, subsurface conditions and characteristics of earth materials between borings can vary. This report should be used for planning and preliminary cost estimating purpose only. This report is not intended for final design.

The data, opinions, and recommendations contained herein are applicable to the specific design elements and locations which are the subject of this report. Data, opinions, and recommendations herein have no applicability to any other design elements or to any other locations, and any and all subsequent users accept any and all liability resulting from any use or reuse of the data, opinions, and recommendations without the prior written consent of EMI.

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Services performed by EMI were conducted in a manner consistent with that level of care and skill ordinarily exercised by members of the profession currently practicing in the same locality under similar conditions. No other representation, expressed or implied, and no warranty or guarantee is included or intended.

11.0 REFERENCES

California Department of Transportation (Caltrans), 2017, ARS Online Web Tool V2.3.09, http://dap3.dot.ca.gov/ARS_Online/

____, 2015a, Standard Specifications.

____, 2015b, Highway Design Manual, December.

____, 2013, Memo To Designers 20-10, January.

California Geological Survey (CGS), 1998, Department of Conservation, Seismic Hazard Zone Report for the Los Alamitos 7.5-Minute Quadrangle, Los Angeles and Orange Counties, California.

California Geological Survey (CGS), 1999 and 1986, Department of Conservation, Earthquake Zones of Required Investigation for the Los Alamitos 7.5-Minute Quadrangle, Los Angeles and Orange Counties, California, Official Map Released: March 25, 1999 for Seismic Hazard Zones and July 1, 1986 for Earthquake Fault Zones.

Department of Water Resources, 1968, Sea-water intrusion: Bolsa-Sunset area, Orange county: Bulletin 63-2, January.

Earth Mechanics, Inc. (EMI), 2017a, Preliminary Materials Report, I-605/Katella Avenue Interchange Improvements Project, Orange County, California, 12-Ora-605, PM 1.1/1.6, May 15.

____, 2017b, Structure Preliminary Geotechnical Report for Retaining Walls, I-605/Katella Avenue Interchange Improvements Project, Orange County, California, 12-Ora-605, PM 1.1/1.6, May 12.

____, 2009, Final Foundation Report for Sign Structures, I-405/I-605 HOV Connector Segment, Orange County, California, 12-Ora-22, 405, 605, PM R0.3/R0.9, 22.3/24.0, 3.0/R1.6, August 10.

Merriam, M., 2012, Caltrans Fault Database (V2b) for ARS Online, California Department of Transportation, Sacramento, CA.

NCEER, 1997, "Proceeding of the NCEER Workshop on Evaluation of Liquefaction Resistance of Soils", T. L. Youd and I. M. Idriss Editors, Technical Report NCEER-97-0022, NCEER, Buffalo, NY.

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Seed, H. B., Idriss, I. M., and Arango, I., 1983,“Evaluation of Liquefaction Potential Using Field Performance Data”, Journal of Geotechnical Engineering, ASCE, Vol. 109, No. 3, pp. 458-482.

Youd, T.L. et al., 2001, Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 127, No. 10, October.

Yerkes, R.F., McColloch, T.H., Schoellhamer, J.E., and Vedder, J.G., 1965, Geology of the Los Angeles Basin, California - an introduction: U.S. Geological Survey, Professional Paper 420.

Zielbauer, E.J., Burnham, W.L., and Keene, A.G., 1961, Alamitos barrier project geologic investigation: Los Angeles County Flood Control District, Coastal Basins Barrier and Replenishment Investigation., May.

APPENDIX A

AVAILABLE LOG-OF-TEST-BORINGS SHEETS

APPENDIX B

AVAILABLE LABORATORY TEST RESULTS

APPENDIX C

RESPONSES TO REVIEW COMMENTS

X:\Projects\2017\17-120 - MBI, I-605 Katella PA-ED\Reports\DPGR\Appendix C. Review Comments and Responses\0K8700_605-Katella_DPGR_Draft1_Response.xlsx Page 1 of 1

Dist-Co-Rte-KP: 12-Ora-605-PM 1.1/1.6Project: I-605/Katella Ave Interchange Improvements Project (0K8700) Code: A = Accept comment

District Preliminary Geotechnical Report - 1st Draft (submitted 6/2017) B = Will not incorporateDate: July 2017 C = Resolution of comment in next submittal

No. Plan/SSP/Page No. Comment Code Response

1 5.1 and Table 1

Subsurface Soil Conditions presented under 5.1 and Table 1 have omitted the potential existence of very soft to soft silt at varying depths in the vicinity of Katella Avenue undercrossing per the provided as-built LOTBs (Borings B-2 and B-4 on Katella Avenue UC). Please incorporate.

A

We will incorporate

2 GeneralPer as-built LOTBs, the existence of very soft to soft silt near Katella Avenue, the settlement/differential settlement might have impacts on the proposed retaining walls and the new embankments.

AWe will update settlement estimates.

District 12 Quality Review Comments - Summary

District Preliminary Geotechnical Report - 1st DraftGeotechnical Design South - C. Jan Wu - rcvd 7/19/17