GEOTECHNICAL REPORT DE LA GARRIGUE AND RICE BRIDGE ...

OAKRIDGE GEOSCIENCE, INC.

GEOTECHNICAL REPORT

DE LA GARRIGUE AND RICE BRIDGE REPLACEMENT PROJECT OAK VIEW, CALIFORNIA

Prepared for: Cannon

January 2019 Job No. 014.002

PO Box 2540, Camarillo, California 93011 www.Oakridgegeo.com

805-603-4900

A DBE/SWBE/SBE Certified Firm

January 11, 2019 Project No. 014.002

Cannon 11900 West Olympic Blvd., Suite 530 Los Angeles, California 90064

Attention: Mr. Michael Kielborn, PE

Subject: Geotechnical Report, De La Garrigue and Rice Bridge Replacement Project, Oak View, California

Dear Mr. Kielborn:

Oakridge Geoscience, Inc. (OGI) is pleased to provide this geotechnical report to Cannon for the De La Garrigue and Rice Bridge Replacement project in the Oak View area of Ventura County, California. The purpose of this report is to summarize the anticipated geotechnical conditions at the two bridge locations and provide geotechnical recommendations in support of the bridge replacement design by Cannon for the Casitas Municipal Water District.

The work was performed in general accordance with our proposal dated August 7, 2018 and was authorized by a Cannon Standard Subcontract for Consulting Services, dated November 26, 2018.

We appreciate the opportunity to provide geotechnical services for Cannon. Please contact us if you have any questions regarding information presented herein.

SINCERELY, OAKRIDGE GEOSCIENCE, INC.

Lori E. Prentice, CEG President

Rory “Tony” Robinson, PE, GE Principal Geotechnical Engineer

Copies Submitted: (one pdf via email)

Cannon Project No. 014.002

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CONTENTS

Page

1.0 INTRODUCTION ...................................................................................................... 11.1 General Statement ........................................................................................... 11.2 Purpose and Understanding ............................................................................ 11.3 Project Description ........................................................................................... 1

1.3.1 De La Garrigue Bridge (Spec. 18-398) ................................................. 11.3.2 Rice Bridge (Spec. 18-401) .................................................................. 1

1.4 Work Performed ............................................................................................... 21.4.1 Data Review and Project Coordination ................................................ 21.4.2 Field Exploration ................................................................................... 21.4.3 Laboratory Testing ............................................................................... 21.4.4 Geotechnical Analyses and Report ...................................................... 3

2.0 FINDINGS ................................................................................................................. 32.1 Site Descriptions .............................................................................................. 3

2.1.1 De La Garrigue Bridge ......................................................................... 32.1.2 Rice Bridge ........................................................................................... 4

2.2 Geologic Setting ............................................................................................... 42.2.1 Regional Geology ................................................................................. 42.2.2 Local Geology ...................................................................................... 4

2.3 Subsurface Conditions and Engineering Properties ........................................ 52.3.1 De La Garrigue Bridge (DH-1) .............................................................. 52.3.2 Rice Bridge (DH-2) ............................................................................... 52.3.3 Engineering Properties ......................................................................... 6

2.4 Groundwater .................................................................................................... 62.5 Potential Variation of Subsurface Materials ..................................................... 72.6 Seismic Considerations and Geohazards ........................................................ 7

2.6.1 Faults .................................................................................................... 72.6.2 Ground Rupture Potential ..................................................................... 72.6.3 Seismic Considerations for 2016 CBC ................................................. 72.6.4 2016 CBC Seismic Design Parameters ............................................... 82.6.5 Liquefaction and Seismically Induced Dry Settlement Potential .......... 92.6.6 Lateral Movement ................................................................................. 92.6.7 Landsliding ........................................................................................... 92.6.8 Expansive and Collapsible Soils ........................................................ 102.6.9 Flooding .............................................................................................. 10


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CONTENTS - CONTINUED

Page

3.0 OPINIONS AND RECOMMENDATIONS ............................................................... 103.1 Summary of Subsurface Site Conditions ....................................................... 103.2 Soil Chemistry and Corrosion ........................................................................ 11

3.2.1 Test Results ....................................................................................... 113.2.2 Corrosion and Cement Considerations .............................................. 11

3.3 Site Grading ................................................................................................... 113.3.1 General Site Clearing and Grubbing .................................................. 113.3.2 Subgrade Preparation ........................................................................ 123.3.3 Fill Material Selection ......................................................................... 123.3.4 Dewatering ......................................................................................... 123.3.5 Fill Placement ..................................................................................... 133.3.6 Compaction ........................................................................................ 13

3.4 Foundation Design ......................................................................................... 143.4.1 Shallow Foundation Design ................................................................ 143.4.2 Allowable Bearing Pressure ............................................................... 143.4.4 Lateral Bearing Pressures .................................................................. 143.4.5 Lateral Loads for Buried Structures .................................................... 153.4.6 Static and Seismic Related Settlements ............................................ 16

3.5 Construction Considerations .......................................................................... 163.5.1 Excavation Conditions ........................................................................ 163.5.2 Temporary Slopes and Excavations ................................................... 173.5.3 Permanent Slopes .............................................................................. 173.5.4 Site Drainage ...................................................................................... 17

4.0 LIMITATIONS ......................................................................................................... 174.1 Report Use ..................................................................................................... 174.2 Hazardous Materials ...................................................................................... 184.3 Local Practice ................................................................................................. 184.4 Plan Review ................................................................................................... 184.5 Construction Monitoring ................................................................................. 18

REFERENCES ................................................................................................................ 19

PLATES

PLATE 1 SITE LOCATIONS PLATE 2 REGIONAL GEOLOGIC MAP

APPENDICES

APPENDIX A FIELD EXPLORATION APPENDIX B LABORATORY TESTING


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1.0 INTRODUCTION

1.1 GENERAL STATEMENT

This geotechnical report summarizes the findings and recommendations of the geotechnical study performed by Oakridge Geoscience, Inc. (OGI) for the De La Garrigue (DLG) and Rice bridge replacement project over the Robles-Casitas Canal (RCC) in the Oak View area of Ventura County, California. The general locations of the project sites are shown on Plate 1.

1.2 PURPOSE AND UNDERSTANDING

The purpose of this report is to summarize the anticipated geotechnical conditions at the two bridge locations and provide geotechnical recommendations in support of the bridge replacement design by Cannon for the Casitas Municipal Water District (CMWD). Our understanding of the project and requirements is based on review of the Requests for Proposal (RFP) by CMWD (Specifications No. 18-398 [DLG bridge] and 18-401 [Rice bridge]) and on discussions with Cannon.

1.3 PROJECT DESCRIPTION

The replacement bridges will span the RCC, an about 33.5-foot-wide, 9.5-foot-deep, concrete-lined diversion canal constructed in the late 1950’s by the US Bureau of Reclamation (USBR) to convey water from the Robles Diversion Dam on the Ventura River to Lake Casitas during the rainy season. Both replacement bridges will be pre-engineered, steel truss structures with concrete decks designed by Contech.

1.3.1 De La Garrigue Bridge (Spec. 18-398)

The DLG bridge project replaces the existing timber bridge that crosses the RCC at about Sta. 235+37 with a single span, pre-engineered steel truss vehicular bridge with a concrete deck that will be approximately 40 feet in length and 20 feet in width.

Initial information from Cannon and Contech indicates the replacement bridge will be a Horizontal Roller Girder Bridge rated as an AASHTO LRFD with HL-93 vehicle loading Rice Bridge (Spec. 18-401)

The Rice bridge project replaces the timber bridge that crossed the RCC at about Station (Sta.) 54+90 that was destroyed by the Thomas Fire in December 2017. The new bridge will be a single span, pre-engineered steel pedestrian bridge, approximately 33 feet in length and eight feet in width.

The Express Bridge plan provided by Contech, indicates the Rice pedestrian/equestrian bridge will have the following bridge reactions:

• Final bridge weight with concrete deck – 27,700 pounds, • Dead load – 6,9251 pounds, • Uniform Live Load – 7,2001 pounds, and • Vehicle Load – 5,0001 pounds.

1 – The vertical reaction loads are distributed onto four base plates for each bridge.


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1.4 WORK PERFORMED

Our proposed work scope was presented in our proposal dated August 7, 2018 and was authorized by a Cannon Standard Subcontract for Consulting Services, dated November 26, 2018. The work performed for this study consists of data review, project-specific field exploration, laboratory testing, geotechnical engineering evaluation, and preparation of this report.

1.4.1 Data Review and Project Coordination

We reviewed readily available published geologic data for the bridge crossing sites and the record drawings provided in the RFP’s. Prior to subsurface exploration, we contacted Underground Service Alert (USA) for utility coordination.

1.4.2 Field Exploration

Field exploration for the project consisted of advancing one hollow-stem-auger drill hole on the southern levee of the RCC at each bridge site to evaluate the subsurface conditions for the replacement bridges. The approximate drill hole locations are indicated on Plate 2. The drill holes were advanced by S/G Drilling of Lompoc, California with a CME 75 drill rig equipped with a 140-pound automatic trip hammer. The drill holes were advanced to depths of 24 feet at the Rice site and 30 feet at the DLG site. The drilling and samples were logged by our field geologist to document excavation conditions and material types. The drill holes were sampled using driven standard penetration test (SPT) or modified California split spoon samplers at about 2-1/2-foot intervals to about 10 feet and at about 5-foot intervals to total depth as indicated on the logs. Additionally, bulk samples were collected from cuttings returned to the ground surface by the auger flights. The drill holes were backfilled to the surface with the excavated materials and the pavement patched with quickset cement upon completion at each location.

The drill hole logs are provided in Appendix A.

1.4.3 Laboratory Testing

Geotechnical laboratory tests were performed on selected earth materials sampled in the drill holes to characterize the earth materials and estimate relevant engineering design parameters. The testing consists of moisture/density measurements, grainsize, compaction, expansion index, and limited chemical testing (sulfates, sulfides, chlorides, pH, and resistivity). The laboratory test results are presented on the drill hole logs (Appendix A) and in Appendix B.


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1.4.4 Geotechnical Analyses and Report

We evaluated the field and laboratory geotechnical data, developed geotechnical engineering recommendations for design of the bridge foundations based on the design concepts provided to us, and prepared this report to summarize our findings, opinions and recommendations. Our report includes the following:

• Summary of work performed and results of our data review; • Drill hole logs and an exploration location map; • Summary of the subsurface soil and groundwater conditions encountered; • Laboratory test results; • Assessment of seismically-related geohazards such as strong ground motion, fault

rupture potential, liquefaction potential, liquefaction-related settlement, and seismically induced settlement;

• Assessment of geologic hazards such as flooding, erosion, slope instability, expansive or collapsible soils;

• Earthwork and grading recommendations, including clearing and grubbing, subgrade soil preparation, compaction requirements, and earthen roadways;

• Suitability of excavated materials for use as fill and select fill; suggested specifications for on-site and imported materials used as fill;

• Foundation parameters including allowable active and passive pressure, allowable bearing pressure, coefficient of friction, lateral earth pressures; and

• Corrosion potential.

2.0 FINDINGS

2.1 SITE DESCRIPTIONS

2.1.1 De La Garrigue Bridge

The DLG bridge project replaces the existing timber bridge that crosses the RCC at about Sta. 235+37 with a single span, pre-engineered steel truss vehicular bridge, approximately 38.5 feet in length and 20 feet in width.

Based on review of the project plans by the USBR (1957), the RCC is a concrete lined trapezoidal channel that is about 9.6 feet deep, about 33.5 feet wide at the ground surface, about seven feet wide at the channel bottom (El. +676.33 feet), with slopes inclined at 1.5 horizontal to 1 vertical (1.5h:1v). The project plans indicate the existing abutments are founded a minimum of five feet below the top of the concrete lined slopes and the center bent is founded about 15 inches below the channel bottom. The plans also indicate the bridge deck is about two feet above the top of the concrete lined channel (El. +685.90 feet).


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2.1.2 Rice Bridge

The Rice bridge project replaces the timber bridge that crossed the RCC at about Station (Sta.) 54+90 that was destroyed by the Thomas Fire in December 2017. The new bridge will be a single span, pre-engineered steel bridge, approximately 33 feet in length and eight feet wide to accommodate pedestrian and equestrian traffic.

Based on review of the project plans (CMWD, undated), the RCC is a concrete lined trapezoidal channel that is about 9.6 feet deep, about 33.5 feet wide at the ground surface, about seven feet wide at the channel bottom, with slopes inclined at 1.5h:1v (similar to the DLG site). The project plans indicate the existing abutments are founded a minimum of five feet below the top of the concrete lined slopes and the center bent is founded about 15 inches below the channel bottom. The plans also indicate the bridge deck is about two feet above the top of the concrete lined channel. We note the elevations on the Rice bridge plans appear to be based on a local datum and were not referenced to the same datum as the DLG plans (USBR, 1957). Survey data by Cannon indicate the ground surface elevation of the abutment areas is about El. +763 feet and the bottom of the channel is at about El. +756 feet.

2.2 GEOLOGIC SETTING

2.2.1 Regional Geology

The project site is located within the Transverse Ranges geologic/geomorphic province of California. That province is characterized by generally east-west-trending mountain ranges composed of sedimentary and volcanic rocks ranging in age from Cretaceous to Recent. Major east-trending folds, reverse faults, and left-lateral strike-slip faults reflect regional north-south compression and are characteristic of the Transverse Ranges. Several authors including the US Geological Survey (USGS, 2006), Dibblee (1987), and Weber (1973) have mapped the Ventura County and Oak View area.

2.2.2 Local Geology

The project sites are located on the western side of the Ventura River Valley. The DLG bridge site is located west of Rancho Matilija and the Rice bridge site is located west of Meiners Oaks. Geologic mapping by the USGS (2006) indicates the surficial sediments at the DLG bridge site consist of Pleistocene-age semi-consolidated silt, sand, clay, and gravel alluvial deposits (Qpa) and the surficial sediments at the Rice bridge site consist of younger Holocene-age unconsolidated alluvial (Qha) deposits of sandy clay with gravel. The USGS maps the bedrock materials exposed in the hillsides in the project vicinity as the Sespe Formation (Ts) consisting of sandstone, siltstone, and claystone that can be pebbly locally. As indicated on the regional geologic mapping by the USGS provided on Plate 2, the Sespe Formation bedrock is folded by a series of east-west trending anticlinal and synclinal folds; the bedrock structure dips to the southeast at about 30 to 35 degrees near the DLG bridge site and dips variably from about 75 degrees to the southeast to about 83 degrees to the northwest near the Rice bridge site.


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2.3 SUBSURFACE CONDITIONS AND ENGINEERING PROPERTIES

Earth materials encountered in the drill holes advanced for this study consist of artificial fill, alluvium, and bedrock of the Sespe Formation as indicated on the logs provided in Appendix A. Descriptions of the earth materials are presented in the following sections.

2.3.1 De La Garrigue Bridge (DH-1)

Artificial Fill (af). Artificial fill materials associated with the access roadway and levee construction were encountered to depth a of about 7-1/2 feet in DH-1 advanced at the DLG bridge site. The pavement profile consisted of about 1-1/2 inches of asphalt concrete pavement over about 2-1/2 inches of oiled sandy base materials. The underlying fill materials consisted of medium stiff to stiff sandy clay with SPT N-value blowcounts ranging from six to 10 blows per foot (bpf).

Alluvium (Qpa). Alluvial sediments were encountered below the fill materials from about 7-1/2 feet to about 20 feet. The alluvial materials sampled in the drill hole consisted of very stiff clay with fine sand and with fine sandstone and siltstone fragments. The SPT N-value blowcounts range from 16 to 19 bpf.

Sespe Formation (Ts). Bedrock of the Sespe Formation was encountered below the alluvial sediments between about 20 to 30 feet (maximum depth explored). The bedrock materials sampled in the drill hole consisted of claystone interbedded with siltstone and sandstone described as highly weathered and soft. The sampled bedrock has soil-like properties and can be described as very stiff to hard clay interbedded with silt and very dense sand. The SPT N-value blowcounts range from 29 to greater than 50 bpf.

Groundwater was not encountered at the DLG bridge site.

2.3.2 Rice Bridge (DH-2)

Artificial Fill (af). Artificial fill materials associated with the access roadway and levee construction were encountered to depth of about 7-1/2 feet in DH-2 advanced at the Rice bridge site. The pavement profile consisted of about 3 inches of asphalt concrete pavement over about 3-1/2 inches of oiled sandy base materials. The underlying fill materials consisted of loose to medium dense clayey sand with SPT N-value blowcounts ranging from seven to 22 bpf.

Alluvium (Qha). Alluvial sediments were encountered below the fill materials from about 7-1/2 feet to about 18-1/2 feet. The alluvial materials sampled in the drill hole consisted of loose to medium dense clayey sand with some fine voids and with coarse sand to fine gravel-size angular rock fragments. The SPT N-value blowcounts ranged from six to 15 bpf. The samples were described as moist to wet, however, groundwater was not recorded in the drill hole.

Sespe Formation (Ts). Bedrock of the Sespe Formation was encountered at a depth of about 18-1/2 feet based on the harder drilling conditions encountered at that depth. The bedrock materials sampled in the drill hole consisted of silty sandstone described as highly weathered and soft. The sampled bedrock has soil-like properties and can be described as very dense silty sand. Refusal to SPT sampling was encountered in the silty sandstone bedrock materials; the drill hole was terminated at a depth of about 24 feet due to difficult drilling conditions and refusal to sampling.


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Groundwater was not encountered at the Rice bridge site.

2.3.3 Engineering Properties

On the basis of the laboratory testing performed for this study, the general engineering parameters for the earth materials sampled in the drill holes advanced for this study consists of the following parameters.

• The dry density of the fill and alluvial materials ranged from 102 to 115 pounds per cubic foot (pcf) in DH-1 and from 109 to 117 pcf in DH-2.

• The moisture contents of the fill and alluvial materials ranged from 15 to 19 percent in DH-1 and from 10 to 17 percent in DH-2.

• Laboratory maximum density tests (ASTM D1557) were performed on selected bulk samples of near surface sandy clay fill materials collected from each drill hole. The test results from both locations indicate maximum dry densities of about 128 pcf and optimum moisture contents of 10 percent for the tested samples. Comparison of the in-place soil moisture contents and densities of samples from DH-1 to the laboratory maximum density curve indicates the moisture contents of the tested soils are five to nine percent above the optimum moisture content and the relative density of the soils is in the range of about 80 to 90 percent. Comparison of the in-place soil moisture contents and densities of samples from DH-2 to the laboratory maximum density curve indicates the moisture contents of the tested soils are near optimum to about three percent above the optimum moisture content and the relative density of the soils is in the range of about 85 to 91 percent.

• The results of grainsize analyses indicate fines contents (percent passing No. 200 sieve) ranging from about 54 to 72 percent for the tested clay and sandy clay samples from DH-1 and 34 to 42 percent for the tested clayey sand samples from DH-2.

• The results of an Expansion Index test (EI) performed on a near surface sample from the DLG bridge site (DH-1), indicates an EI of 78 (medium expansion potential).

• The results of the soil chemistry tests are summarized in Section 0 below.

2.4 GROUNDWATER

Groundwater was not encountered in either of the drill holes advanced for this study. We note samples of the alluvial soils from the Rice bridge site were described as moist to wet, however, groundwater was not encountered during drilling at that location. The CGS (2003) indicates historical high groundwater may be within about 40 feet of the ground surface at both locations. However, the bridge sites are located within easterly trending tributary drainage areas and on the levees of the RCC which conveys diverted water to Lake Casitas following precipitation events. Therefore, the potential exists for groundwater to be encountered at the project sites, most likely as transit flow along the alluvium/bedrock contact during periods of heavy precipitation.


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2.5 POTENTIAL VARIATION OF SUBSURFACE MATERIALS

There is a potential for variation in the consistency, density, and strength/hardness of the materials from what was encountered in our explorations. The potential exists to encounter perched water, zones of poorly consolidated soils, well indurated, very hard bedrock materials, or other conditions not indicated on the exploration logs. If significant variation in the geologic conditions is observed during construction, we recommend the geotechnical engineer, in conjunction with the project designer, evaluate the impact of those variations on the project design.

2.6 SEISMIC CONSIDERATIONS AND GEOHAZARDS

2.6.1 Faults

The project sites are located in the seismically active southern California area and the project most likely will be subjected to strong earthquake ground motion during its lifetime. As summarized in Table 1, numerous active or potentially active faults are known or postulated to exist within about 20 miles of the site.

Table 1. Nearby Faults

Fault Approximate Distance (km)

Maximum Moment Magnitude (Mmax)

Mission Ridge/Arroyo Parida/Santa Ana 1.1 7.4

Sisar 8.0 7.6

Santa Ynez 8.1 7.5

Red Mountain 8.4 7.0

North Channel 10.5 6.4

Ventura-Pitas Point 14.4 7.5

Earthquake magnitudes obtained from the USGS website, http://geohazards.usgs.gov/cfusion/hazfaults_search/hf_search_main.cfm

2.6.2 Ground Rupture Potential

The sites are not located within a State of California Earthquake Fault Zone (formerly Alquist-Priolo Special Studies Zone) and no known active or potentially active faults cross or trend toward the site. The potential for fault rupture to affect the sites is considered low.

2.6.3 Seismic Considerations for 2016 CBC

We estimated the probabilistic seismic hazards for the site using the USGS Interactive Deaggregations web application. On the basis of the web-based analyses, the peak horizontal ground acceleration (pga) at the project sites is estimated to be about 0.89g for an earthquake event with a 2,475-year return period (2 percent probability of exceedance in 50 years) assuming Site Class D soil conditions. Table 2 summarizes the probabilistically estimated strong ground motion parameters for the project site.


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Table 2. Summary of USGS Probabilistic Seismic Hazard Deaggregation Results

Return Period (years)

Mean Magnitude (Mw)

Mean Source Distance (km)

Peak Horizontal Ground Acceleration

2,475 7.1 6.9 0.84 g

2.6.4 2016 CBC Seismic Design Parameters

In accordance with Chapter 16, Section 1613 of the 2016 CBC, the following parameters have been obtained from the USGS Seismic Design Maps web application and shall be incorporated into the seismic design at the subject site. The subsurface conditions at the site are considered to satisfy the parameters for Site Class D and the associated seismic design parameters for use in generating the risk-targeted maximum considered earthquake and design level spectra are summarized in Table 3. The sites are located nearly three miles apart; for this study we have reported the DLG site values, which are slightly higher than values estimated for the Rice Bridge site.

Table 3. 2013 CBC Seismic Design Parameters, Site Class D

2013 California Building Code Section 1613

Seismic Parameter Value

--- Latitude 34.4287

--- Longitude -119.3269

Figure 1613.3.1(1) Mapped Acceleration Response Parameter (Ss) 2.245g

Figure 1613.3.1(2) Mapped Acceleration Response Parameter (S1) 0.823g

Section 1613.3.2 Site Class D

Section 1613.3.3 and Table 1613.3.3(1) Site Coefficient (Fa) 1.0

Section 1613.3.3 and Table 1613.3.3(2) Site Coefficient (Fv) 1.5

Section 1613.3.3 Adjusted Acceleration Response Parameter for Site Class D (SMS) 2.245g

Section 1613.3.3 Adjusted Acceleration Response Parameter for Site Class D (SM1) 1.235g

Section 1613.3.3 Adjusted Acceleration Response Parameter for Site Class D (SDS) 1.497

Section 1613.3.3 Adjusted Acceleration Response Parameter for Site Class D (SD1) 0.823g

Figure 22-7 Peak Ground Acceleration 0.839

Section 1613.3.3 Equation 11.8-1 PGAM = FPGAPGA 0.839g


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2.6.5 Liquefaction and Seismically Induced Dry Settlement Potential

Liquefaction is described as the sudden loss of soil strength because of a rapid increase in soil pore water pressures due to cyclic loading during a seismic event. In order for liquefaction to occur, three general geotechnical characteristics must be present: 1) groundwater must be present within the potentially liquefiable zone; 2) the potentially liquefiable soil must meet certain grain size and classification characteristics; and 3) the potentially liquefiable granular soil must be of low to moderate relative density. If those criteria are met and strong ground motion occurs, then those soils may liquefy, depending upon the intensity and cyclic nature of the strong ground motion. Liquefaction that produces surface effects generally occurs in the upper 40 to 50 feet of the soil column, although the phenomenon is not restricted to depths of less than 50 feet.

The sites are underlain by medium stiff to stiff sandy clay underlain by Sespe Formation bedrock below about 20 feet (DLG) and loose to medium dense clayey sand underlain by Sespe Formation bedrock below about 18-1/2 feet (Rice). Groundwater was not encountered in the fill and alluvial materials or at the bedrock contact at the time of exploration, however, as noted above, the potential exists for transit groundwater to be present during periods of heavy precipitation. The potential for liquefaction to occur within the sandy clay to clayey sand soils as a result of a seismic event is considered to be low.

Based on our evaluation, there is a potential for the medium dense, clayey sand soils in the upper 18 to 20 feet of the Rice site to experience seismically-induced dry settlement in response to the design level earthquake. The estimated seismically-induced dry settlement is in the range of 2 to 2-1/2 inches, however, based on the high percentage of clay fines, the estimated seismically-induced settlement is probably conservative.

2.6.6 Lateral Movement

The occurrence of lateral spreading is generally associated with sites where liquefaction is possible and: 1) the ground surface is sloping, or 2) there is a free face condition such as a road cut or riverbank. This project sites have relatively low slopes (about one percent) but, the bridges span the RCC, which has about 9.6-foot high, 1.5h:1v slopes. Existing analytical methods of assessing potential deformations caused by lateral spreading are based on a small number of case histories and generally involve layers of liquefiable soils of greater than three feet. The procedures are generally considered reasonable in assessing risks where significant lateral deformations are possible (deformations of a meter or greater). The ability to reasonably predict small lateral spreading deformations is, however, considered significantly limited.

Based on the subsurface data, the potential for liquefaction to impact the sites is low thus the potential for lateral movement of the soil is anticipated to be minimal.

2.6.7 Landsliding

The sites are located on a gently sloping alluvial plains and no large-scale landslides are mapped in the immediate site vicinities based on regional geologic maps or were observed during our field reconnaissance. The potential for slope instability to affect the sites is low.


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2.6.8 Expansive and Collapsible Soils

The onsite near-surface granular soils encountered in during site exploration have medium expansion potential based on the results of laboratory testing (EI of 78). The foundation design includes overexcavation of the moderately expansive soil and replacement with aggregate base.

2.6.9 Flooding

The project consists of replacement bridges over the RCC concrete-lined channel constructed to convey water from the Ventura River to Lake Casitas. Because the sites are located downstream of the Los Robles diversion structure which regulates flow from the Ventura River into the channel, the potential for damaging flows to impact the bridges is considered low. We note the potential does exist for flow within the channel to locally damage the concrete lining potentially resulting in damage to the bridge foundations.

3.0 OPINIONS AND RECOMMENDATIONS

3.1 SUMMARY OF SUBSURFACE SITE CONDITIONS

The geotechnical conditions for the project were evaluated based on the explorations and laboratory testing performed for this study supplemented by regional geologic data from the project area.

• The sites are underlain by medium stiff to stiff sandy clay underlain by Sespe Formation bedrock below about 20 feet (DLG) and loose to medium dense clayey sand underlain by Sespe Formation bedrock below about 18-1/2 feet (Rice) as indicated on the logs in Appendix A.

• Groundwater was not encountered in the fill and alluvial materials or at the bedrock contact at the time of exploration, however, the potential exists for groundwater to be present at other times.

• The sites are located in seismically active area and has a relatively high peak ground acceleration of 0.839g.

• Based on the site conditions, the proposed bridge foundations can be supported on shallow spread footings with a minimum burial depth of three feet below grade. If desired the bridges could also be supported on drilled piers bearing in Sespe Formation bedrock at a depth of about 20 feet.


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3.2 SOIL CHEMISTRY AND CORROSION

3.2.1 Test Results

Two selected soil samples obtained from our explorations were provided to Cooper Testing Laboratories for resistivity, pH, chloride, and sulfate testing. The test results are summarized below and the laboratory test reports are included in Appendix B.

Table 4. Summary of Chemical Test Results

Drill Hole

USCS Classification

Depth (feet)

Sulfate (mg/kg)

Sulfate) (%)

Chloride (mg/kg)

Resistivity (ohm-cm)

pH

DH-1 DLG

Sandy CLAY (CL) 0 – 5 103 0.0103 3 1,267 7.5

DH-2 Rice

Sandy CLAY (CL) 0 – 5 128 0.0128 <2 2,135 7.7

3.2.2 Corrosion and Cement Considerations

Many factors can affect the corrosion potential of soil including soil moisture content, resistivity, permeability, and pH, as well as chloride and sulfate concentration. Caltrans (2018) considers soils to be corrosive or to represent a corrosive environment if one of the following criteria is met:

• Resistivity value of less than 1,000 ohm-cm; • Chloride content of 500 ppm or greater; • Sulfate concentration of 2,000 ppm or greater; or • pH is 5.5 or less.

As summarized in the table above, the measured properties indicate the soil materials from DH-1 and DH-2 are considered non-corrosive to concrete or steel based on the test data and Caltrans limits.

The test results should be evaluated by a corrosion specialist to confirm the opinions regarding the potential corrosion impacts from the onsite soils to the construction materials proposed for the project.

3.3 SITE GRADING

3.3.1 General Site Clearing and Grubbing

Soil containing debris, organics, trees and root systems, and other unsuitable materials should be excavated and removed from improvement areas prior to commencing grading operations. Areas should be cleared of old foundations, slabs, pavement, abandoned utilities, and soils disturbed during the demolition process. Depressions or disturbed areas left from the removal of such material should be replaced with compacted fill.


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3.3.2 Subgrade Preparation

Following site clearing, we recommend the sandy clay/clayey sand soils be removed to depth of one-foot below the proposed footing plus one foot on each side of the footing. The resulting surface should be scarified to a depth of at least nine inches, moisture conditioned and compacted to 90 percent relative compaction. The overexcavation should be brought back up to grade with aggregate base meeting the project specifications listed below. The aggregate base should be compacted to 95 percent relative compaction. The intent of the overexcavation and recompaction is to provide a uniform bearing surface for the bridge foundations and reduce potential for the moderately expansive clayey soil to impact the foundations.

3.3.3 Fill Material Selection

Recommended fill material selection requirements for subgrade fill, aggregate base, and use of onsite materials are presented below. Areas or zones where the various fill materials may be used are described below.

Compacted Fill. As described above, the near-surface materials encountered in the drill holes consist of clay, sandy clay, and clayey sand with varying amounts of gravel/rock fragments. Granular soil materials generated from the overexcavation (clayey sand; less than 50 percent fines) can be utilized as compacted fill as long as those materials satisfy criteria for general fill listed below and oversize materials removed from the fill. Fine grained, moderately expansive sandy clay and clay soil should not be used as fill beneath or against bridge foundations but maybe be used outside of structural zones. Material derived from the overexcavation may also generate oversize material that may need to be processed and removed so that the soil can be use as onsite fill.

General Fill. General fill should consist of granular soil materials (SP, SW, SM, and SC) free of organics, oversize rock (greater than six inches in diameter), trash, debris, and other deleterious or unsuitable materials, and should have an expansion index less than 50. The fill materials should have less than 15 percent larger than three inches in diameter and cobbles larger than six inches should be removed from the fill.

Aggregate and Miscellaneous Base. Base materials should consist of material conforming to Caltrans Standard Specifications for Class 2 Aggregate Base, Section 26-1.02 (Caltrans, latest version) or Section 200-2.5 of the Greenbook (2018) for Processed Miscellaneous Base.

Imported Fill. Although importing fill is not anticipated, if material is imported, the imported subgrade fill materials should comply with recommendations for general fill or as appropriate for its intended use. Imported fill should be reviewed by the geotechnical engineer prior to being transported to the site.

3.3.4 Dewatering

On the basis of our subsurface exploration, we do not anticipate groundwater will be encountered during site grading activities. Although we do not anticipate the need for dewatering, groundwater levels may vary seasonally and it is possible some seepage may be encountered in the excavations following rain, localized irrigation, or canal diversion operations.


13


3.3.5 Fill Placement

Fill should be placed, moisture conditioned, and compacted to a minimum of 95 percent relative compaction beneath the foundations plus one foot outside the footings and 90 percent relative compaction for general fill and backfill against the foundations. In general, we recommend the moisture content of the fill should be 0 to 2 percent above the optimum. We note the tested soils at the DLG site have moisture contents in the range of 15 to 19 percent and the tested soils at the Rice site have moisture contents in the range of 10 to 17 percent. On the basis of the test results, the onsite soil may need to be dried back during grading to bring the moisture content to near the optimum moisture content of about 10 percent. Each layer should be spread evenly and should be thoroughly blade-mixed during the spreading to provide relative uniformity of material within each layer. Soft or yielding materials should be removed and be replaced with properly compacted fill material prior to placing the next layer.

Rock, cobbles, and other oversized material greater than six inches in dimension in any direction should be removed from the fill material being placed. The contractor should be prepared to screen all materials prior to placement as compacted fill. Rocks should not be nested and voids should be filled with compacted material. Organics, foreign matter, and other deleterious materials also should be removed from any material used in constructed fills.

Fill and backfill materials should be placed in layers that can be compacted with the equipment being used. Fill should be spread in lifts no thicker than approximately eight inches prior to being compacted. Fill and backfill materials may need to be placed in thinner lifts to achieve the recommended compaction depending on the equipment being used.

3.3.6 Compaction

Fill placement and grading operations should be performed according to Greenbook Specification 300-4, and the grading recommendations of this report. Relative compaction should be assessed based on the latest approved edition of ASTM D1557. The foundation over-excavation and upper one-foot of any road section modifications (subgrade plus base materials) should be compacted to 95 percent relative compaction. We recommend general fill be compacted to a minimum of 90 percent relative compaction. The recommended specified relative compaction should extend to a minimum of three feet horizontally beyond the limits of the improvements. Density testing should be performed a minimum of every two vertical feet and one test per every 100 cubic yards of fill placed.


14


3.4 FOUNDATION DESIGN

3.4.1 Shallow Foundation Design

The proposed bridge foundations can be supported on a shallow foundation system consisting of spread footings using California Building Code and Greenbook requirements.

3.4.2 Allowable Bearing Pressure

Spread footings for the bridge foundations can be supported on compacted aggregate base materials. For these conditions, we recommend shallow footings be designed using a maximum allowable bearing pressure of 2,000 pounds per square foot (psf). The allowable value incorporates a factor of safety of at least 3. The toe-pressure below retaining walls or eccentrically loaded footings can exceed the recommended bearing pressure, provided the resultant pressure is within the middle-third of the footing. In accordance with 2016 CBC Section 1806.1, the bearing values indicated above are for static loads (including the total of dead and frequently applied live loads), and may be increased for short duration loading (including the effects of wind or seismic forces) as allowed in 2016 CBC Section 1605.3.2. The allowable bearing capacity can be increased by seven percent for each foot of embedment (i.e. depth) or width to a maximum value of twice the allowable bearing pressure.

3.4.3 Minimum Embedment Depth and Width

In general, footings embedded in fill materials should extend to at least three feet below the lowest adjacent grade and have a minimum width of 24 inches. Isolated pad footings should be at least three feet in least dimension.

3.4.4 Lateral Bearing Pressures

In accordance with 2016 CBC Section 1806.3.1, resistance to lateral loading may be provided by both friction acting at the base of foundations and by lateral bearing pressure. The presumptive values for lateral bearing pressure given within 2016 CBC, Table 1806.2 as well as the allowable increase for depth noted in 2016 CBC Section 1806.3.3 shall be superseded by the site-specific values in the following table. The lateral bearing pressure in the upper one-foot of the site should be neglected unless the ground surface is covered with asphalt or concrete, and the lateral bearing pressure may be increased by 300 psf for each additional foot of embedment to a maximum value of 2,500 psf for level ground adjacent to the structure. If the horizontal distance between the base of the footing and canal slope face is less than five feet, the lateral bearing pressure and associated depth increase should be decreased to 150 psf/ft.


15


Table 5. Summary of Lateral Bearing Pressures

Allowable Bearing Material1

Allowable Lateral Bearing

Pressure2

Maximum Lateral Bearing

Pressure3

Allowable Coefficient of

Friction4

Level Pad Surfaces

Old Marine Deposits/compacted fill

300 psf/ft 2,500 psf 0.35

1 These allowable bearing materials supersede the presumptive materials given within 2016 CBC Section 1809.2. These materials must be undisturbed and verified in the field at the time of construction by the Project Engineering Geologist/Geotechnical Engineer in accordance with 2016 CBC Section 1705.6 and Table 1705.6.

2 These allowable lateral bearing pressures supersede the presumptive values given within 2016 CBC Table 1806.2. Requires a minimum of five of soil horizontally between the edge of footing and canal slope face. If the horizontal distance is less than 5 feet the allowable lateral bearing pressure should be reduced to 150 psf/ft.

2 In accordance with 2016 CBC Section 1806.1, the allowable passive earth pressure indicated above is for static loads (including the total of dead and frequently applied live loads), and may be increased by one-third for short duration loading (including the effects of wind or seismic forces) as allowed in 2016 CBC Section 1805.3.2.

3 These maximum lateral bearing pressures supersede the presumptive maximum value given within 2016 CBC Section 1806.3.3

4 These allowable coefficients of friction supersede the presumptive values given within 2016 CBC Table 1806.2. In accordance with 2016 CBC Section 1806.3.2, lateral sliding resistance shall not exceed one-half of the dead load.

3.4.5 Lateral Loads for Buried Structures

Retaining structures free to rotate or translate laterally (e.g., cantilevered retaining walls) through a horizontal distance to wall height ratio of greater than about 0.004 can be assumed as unrestrained or yielding retaining structures. Such walls can generally move enough to develop active conditions. Retaining structures unable to rotate or deflect laterally (e.g., restrained below-grade or basement walls) are referred to as restrained or rigid walls.

The presumptive values for lateral soil load given within 2016 CBC, Table 1610.1 shall be superseded by the following site-specific values. These load values are expressed as equivalent fluid densities (consistent with CBC) and are intended for structural design of buried walls and retaining walls of up to a maximum of 20 feet in retained height.


16


Table 6. Lateral Earth Loads

Average Slope Gradient Above Wall

Active Lateral Soil Load (pcf)1

At-Rest Lateral Soil Load (pcf)2

Seismically Induced Soil Load (pcf)3

Level 45 65 20 1, 2 These load values supersede the presumptive values for lateral soil loads given within 2016 CBC, Table 1610.1.

Additional surcharge from other structures shall be included in the design of the wall. This listed soil pressure is for supporting soils with a prevailing Expansive Index (EI) of no greater than 20. Soils with an EI greater than 20 shall not be used as backfill material.

1 This listed soil pressure assumes the wall will be allowed to deflect between 0.01H to 0.02H, in accordance with 2016 CBC Section 1610.1.

2 Applicable to restrained wall conditions, in accordance with Section 1610.1 of the 2016 CBC. 3 In accordance with 2016 CBC Section 1803.5.12, if it is anticipated that the earthquake induced acceleration for

the site will exceed 0.4g, then seismic loading may be applied to walls of at least six feet or taller in accordance with Section 1610.1 of the 2016 CBC at the option of the Project Structural Engineer. When utilized, this loading may be applied as an inverted -oriented triangular-load.

3.4.6 Static and Seismic Related Settlements

Static settlements generally will occur in response to foundation loads on the foundation support material. The estimated static settlement due to loading ranges from 1/2- to 3/4-inch. The structure should be designed to accommodate static differential settlements of at least 1/2-inch over a distance of 30 feet (i.e., a distortion ratio of approximately 1/720) for similarly sized and loaded footings. As described in Section 2.6 of the report, the estimated seismically-induced dry settlement is in the range of 2 to 2-1/2 inches. The seismic settlement should be considered in addition to static settlements.

If the total static plus dynamic settlement exceeds bridge foundation specifications, the bridge could be founded on drilled piers founded in Sespe Formation bedrock at a depth of about 20 feet or a portion of the alluvial soils could be overexcavated and recompacted as structural fill to reduce the potential for seismically-induced dry settlement. Based on our review of information on the Contech website, it appears the estimated settlements should be reasonable for the anticipated bridge type.

3.5 CONSTRUCTION CONSIDERATIONS

3.5.1 Excavation Conditions

Subsurface materials encountered in explorations for this study within the anticipated construction profiles consisted of medium stiff to stiff sandy clay (DLG) and loose to medium dense clayey sand (Rice) with varying amounts of gravel/rock fragments. The excavations may generate oversized material (greater than six-inches in diameter) that will need to be processed on-site to place as compacted fill. In addition, the soil will need to be moisture conditioned, either drying back or adding water, to achieve moisture content near the optimum moisture content.


17


3.5.2 Temporary Slopes and Excavations

The contractor should be responsible for the design of temporary slopes. Within the anticipated depths of excavation, the soil profile is anticipated to consist of medium stiff sandy clay and loose to medium dense clayey sand soil materials with varying amounts of gravel/rock fragments. Temporary slopes should be braced or sloped according to the requirements of OSHA.

As input to design, excavations in granular soil without shoring can be classified as Type C and should be sloped no steeper than 1.5h:1v as deemed appropriate based upon classification Type determined in the field per OSHA guidelines. We recommend all temporary excavations be monitored for signs of instability and appropriate actions (such as flattening the slope, providing shoring, and controlling groundwater, if encountered) should be undertaken if evidence of potential instability is observed. Table 7 summarizes parameters for consideration in the design of temporary slopes or shoring systems.

Table 7. Engineering Parameters for Design of Temporary Slopes and Shoring1

Soil Unit Total Unit Weight

(pcf) Friction Angle

(degrees) Cohesion

(psf)

Clayey Sand (SC) 130 32 0

1 Parameters provided here are valid only for the design of temporary slopes and shoring.

3.5.3 Permanent Slopes

Permanent cut-slopes should be inclined at 2h:1v or flatter.

3.5.4 Site Drainage

Site grading should be provided such that positive drainage away from improvements is provided. Water should not be allowed to pond near the improvements. We recommend the construction of finished slopes of 1 to 2 percent away from the improvements. Erosion control and maintenance of the slopes should be provided to reduce the potential for erosion.

4.0 LIMITATIONS

4.1 REPORT USE

This report has been prepared for the exclusive use of Cannon and the Casitas Municipal Water District for the design and construction of the proposed De La Garrigue and Rice Bridge Replacement Project. The findings, conclusions, and recommendations presented herein were prepared in accordance with generally accepted geotechnical engineering practices of the project region. No other warranty, express or implied, is made.

Although information contained in this report may be of some use for other purposes, it may not contain sufficient information for other parties or uses. If any changes are made to the project as described in this report, the conclusions and recommendations in this report shall not


18


be considered valid unless the changes are reviewed and the conclusions and recommendations of this report are modified or validated in writing by OGI.

4.2 HAZARDOUS MATERIALS

This report does not provide information regarding the presence of hazardous/toxic materials in the soil, surface water, groundwater, or atmosphere.

4.3 LOCAL PRACTICE

In performing our professional services, we have used generally accepted geologic and geotechnical engineering principles and have applied the degree of care and skill ordinarily exercised under similar circumstances by reputable geotechnical engineers currently practicing in this or similar localities. No other warranty, express or implied, is made as to the professional advice included in this report.

4.4 PLAN REVIEW

We recommend OGI be provided the opportunity to review and comment on the geotechnical aspects of any project plans and specifications prepared for this project before they are finalized. The purpose of that review will be to evaluate if the recommendations in this report have been properly interpreted and implemented in the design and specifications.

4.5 CONSTRUCTION MONITORING

Users of this report should recognize the construction process is an integral design component with respect to the geotechnical aspects of a project, and geotechnical engineering is inexact due to the variability of natural and man-induced processes, which can produce unanticipated or changed conditions. Proper geotechnical observation and testing during construction is imperative in allowing the geotechnical engineer the opportunity to verify assumptions made during the design process. Therefore, we recommend OGI be retained during project construction to observe compliance with project plans and specifications and to recommend design changes, if needed, in the event that subsurface conditions differ from those anticipated.


19


REFERENCES

American Concrete Institute (2014), ACI 318-14, Building Code Requirements for Structural Concrete

American Society of Civil Engineers (2010), ASCE Standard 7-10, Minimum Design Loads for Buildings and Other Structures.

California Building Code (2016), 2016 California Building Code, published by the International Conference of Building Officials, Whittier, California.

California Geological Survey (CGS, 2003), Seismic Hazard Zone Report for the Matilija 7.5-Minute Quadrangle, Ventura County, California, SHZR 064.

Casitas Municipal Water District (CMWD, undated), Restoration of Rice Canyon Timber Bridge, Robles-Casitas Canal (Sta 54+90) Plan, Sections & Details.

Dibblee, T.W., Jr. (1987), Geologic Map of the Matilija Quadrangle, Ventura County, California: Dibblee Geological Foundation, Map DF-12, Scale 1:24,000.

Seed, H. B. and I. M. Idriss (1971), Simplified Procedure for Evaluating Soil Liquefaction Potential, J. Geotech. Engrg. Div, ASCE, 97(9), 1249-1274.

United States Geological Survey (USGS, 2006), Geologic Map of the Matilija 7.5-Minute Quadrangle, Ventura County, California

USGS , https://geohazards.usgs.gov/deaggint/2017

US Bureau of Reclamation, (USBR, 1957), Ventura River Project-Calif Robles-Casitas Diversion Canal Sta. 235+36.90, Timber Farm Bridge, As-Built Plans dated 5-14-59.

Weber, H.F., Jr., et al. (1973), in Geology and Mineral Resources Study of Southern Ventura County, California, California Division of Mines and Geology (CDMG) Preliminary Report No. 14, 102 pp.

Youd, T. L. and I. M. Idriss (2001), Liquefaction Resistance of Soils: Summary Report form the 1996 NCEER and 1998 NCEER/NSF Workshop on Evaluation of Liquefaction Resistance of Soils, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 127(4), 297-312.

PLATES

OAKRIDGE GEOSCIENCE, INC.Cannon Project No. 014.002

SITE LOCATIONS De La Garrigue and Rice Bridge Replacement Project

Oak View, CaliforniaPLATE 1

De La Garrigue Bridge Site

(DH-1)

Rice Bridge Site

(DH-2)

Source: USGS Topographic Map

OAKRIDGE GEOSCIENCE, INC.Cannon Project No. 014.002

REGIONAL GEOLOGIC MAP De La Garrigue and Rice Bridge Replacement Project

Oak View, CaliforniaPLATE 2

De La Garrigue Bridge Site

(DH-1)

Rice Bridge Site

(DH-2)

Sou

rce:

US

GS

(200

6)

N Approx. Scale (feet)0 1,200 2,400

Qw - Alluvial Deposits Active Wash

Ts - Sespe FormationQpa - Alluvial Deposits (late Pleistocene)Qha - Alluvial Deposits (Holocene)Approximate overturned bedding orientation

Approximate bedding orientation23

Approximate location of mapped fault traceApproximate location anticlinal/synclinal axis

65

APPENDIX A

1 -- 17 54

p2.0

2 (10) 102 19 t0.8

3 10 15 66 p2.5

p3.5

4 (27) 115 15 p>4.5

t>1.0

5 16 16 72

6 (29) 111 18 p4.5

PLA

ST

ICIT

Y

(LL/

PI)

%

PA

SS

ING

N

o. 2

00

LOG OF DRILL HOLE DH-1

NU

MB

ER

LOCATION: De La Garrigue Bridge

MA

TE

RIA

L

SY

MB

OL

SA

MP

LE

BLO

W C

OU

NT

DR

Y D

EN

. (pc

f)

MO

IST

UR

E

CO

NT

EN

T %

MATERIAL DESCRIPTION

30'

DE LA GARRIGUE AND RICE BRIDGE REPLACEMENT PROJECT

669

18

667

BACKFILL:

Not Encountered

L Prentice

C Prentice

LOGGED BY:

CHECKED BY:

S/G Drilling

Cuttings

NOTE: The log and data presented herein are a simplification of actual

subsurface conditions encountered at the time of exploration at the specific

location explored. Subsurface conditions may differ at other locations and

at this location with the passage of time.

ALLUVIUM (Qpa)

CLAY (CL): very stiff, moderate brown, damp, with fine sand

2

DATE:

METHOD:

673

677

10

TOTAL DEPTH (ft):

8" Hollowstem auger

December 17, 2018

- medium stiff, with yellowish silty inclusions, some fine sand, and trace woody debris, at 2-1/2'

14

16

WATER DEPTH (ft):

CONTRACTOR:

12

4

675

Sandy CLAY (CL): stiff, moderate yellowish brown, damp

Cannon

Oak View, California

PLATE A-1a

6

679

8

671

- with fine sandstone and siltstone fragments and fine caliche veinlets, at 15'


681

683

ARTIFICIAL FILL (af)

1-1/2" ac over about 2-1/2" of oiled sandy base materialsSandy CLAY (CL): moderate yellowish brown, damp to moist

685

SURFACE EL. (ft): Approx. 686'

Project No. 014.002

TV

or

PP

(t

sf)

ELE

V. (

ft)D

EP

TH

(ft)

7 29

8 (50:3) 5 18

9 50:2

LOG OF DRILL HOLE DH-1 (Continued)

MATERIAL DESCRIPTION

CannonProject No. 014.002


ELE

V. (

ft)D

EP

TH

(ft)

MA

TE

RIA

L

SY

MB

OL

SA

MP

LE

NU

MB

ER

BLO

W C

OU

NT LOCATION: De La Garrigue Bridge

DR

Y D

EN

. (pc

f)

MO

IST

UR

E

CO

NT

EN

T %

PLA

ST

ICIT

Y

(LL/

PI)

%

PA

SS

ING

N

o. 2

00

TV

or

PP

(t

sf)

SESPE FORMATION (Tsp)

665CLAYSTONE (Rx): highly weathered, soft, reddish brown, interbedded with yellowish brown siltstone, blocky texture,

22 apparent dip approx. 20 deg. [CLAY (CL) interbedded with SILT (ML): very stiff to hard]

663 - harder drilling below about 20'

24

661SANDSTONE (Rx): highly weathered, soft, pale yellowish brown, damp

26 fine grained [Silty SAND (SM): very dense]

659

28

657

30

655

32

653

34

651

36

649

38

L Prentice

8" Hollowstem auger

647

CONTRACTOR: S/G DrillingNOTE: The log and data presented herein are a simplification of actual




TOTAL DEPTH (ft):



PLATE A-1b

DATE: December 17, 2018 CHECKED BY: C Prentice


30'

METHOD: WATER DEPTH (ft): Not Encountered

BACKFILL: Cuttings LOGGED BY:

1 -- 10 34

2 (11) 117 11 44

3 22

4 (9) 109 12

5 12 13 42

6 (24) 113 17

LOG OF DRILL HOLE DH-2

CannonOAKRIDGE GEOSCIENCE, INC.Project No. 014.002


MATERIAL DESCRIPTIONELE

V. (

ft)D

EP

TH

(ft)

MA

TE

RIA

L

SY

MB

OL

SA

MP

LE

NU

MB

ER

BLO

W C

OU

NT LOCATION: Rice Bridge

DR

Y D

EN

. (pc

f)

MO

IST

UR

E

CO

NT

EN

T %

PLA

ST

ICIT

Y

(LL/

PI)

%

PA

SS

ING

N

o. 2

00

TV

or

PP

(t

sf)

ARTIFICIAL FILL (af)

1023" ac over about 3-1/2" of oiled sandy base materialsClayey SAND (SC): reddish brown, moist, with yellowish sand

2

100 - loose, with yellowish sandstone fragments, at 2-1/2'

4

98Clayey SAND (SC): medium dense, reddish brown, damp to moist,

6 with angular reddish and yellowish sandstone fragments; blowcounts may be affected by rock fragment content

96

8ALLUVIUM (Qha)

Clayey SAND (SC): loose, reddish brown mottled with light brown,

94 moist, with trace organics and fine voids

10 - medium dense, at 10'

92

12

90

14

88 - with coarse sand to fine gravel-size angular rock fragments, moist

16 to wet, with iron oxide stain, at 15'

86

18 - harder drilling below about 18-1/2'

84SESPE FORMATION (Tsp)





TOTAL DEPTH (ft):

DATE: December 17, 2018

PLATE A-2a

24'

METHOD: 8" Hollowstem auger WATER DEPTH (ft): Not Encountered

BACKFILL: Cuttings LOGGED BY: L Prentice

CHECKED BY: C Prentice



7 ref

8 ref

LOG OF DRILL HOLE DH-2 (Continued)

CannonOAKRIDGE GEOSCIENCE, INC.Project No. 014.002


MATERIAL DESCRIPTIONELE

V. (

ft)D

EP

TH

(ft)

MA

TE

RIA

L

SY

MB

OL

SA

MP

LE

NU

MB

ER

BLO

W C

OU

NT LOCATION: Rice Bridge

DR

Y D

EN

. (pc

f)

MO

IST

UR

E

CO

NT

EN

T %

PLA

ST

ICIT

Y

(LL/

PI)

%

PA

SS

ING

N

o. 2

00

TV

or

PP

(t

sf)

SESPE FORMATION (Tsp)

82Silty SANDSTONE (Rx): highly weathered, soft, reddish brown, near vertical apparent dip [Silty SAND (SM): very dense, dry]

22 - refusal to sampling, at 20'; very hard drilling below 20'

80

24 - refusal to sampling, at 24'

78

26

76

28

74

30

72

32

70

34

68

36

66

38

64





TOTAL DEPTH (ft):

DATE: December 17, 2018

PLATE A-2b

24'

METHOD: 8" Hollowstem auger WATER DEPTH (ft): Not Encountered

BACKFILL: Cuttings LOGGED BY: L Prentice

CHECKED BY: C Prentice




Blowcount

Push,

or Grab

1 Bulk Bulk SampleBlowcount Description

2 23 Standard Penetration Test (SPT) 63 63 blows for 1' penetration after initial 6" seatingSampler (1-3/8" ID/2" OD) driven 89/11 89 blows for 11" penetration after initial 6" seating

33/6 33 blows for 6" drive after initial 6" seating3 (23) Modified California Liner Sampler Ref >50 blows for initial 6" seating

driven ( 2-3/8" ID/3" OD) (23) Blowcounts for modified California sampler

4 Push Thin-walled samplerpushed ( 2-7/8" ID/3" OD)

5 (23) Modified California Liner Sampler (disturbed)driven ( 2-3/8" ID/3" OD)

Lean CLAY (CL) Sandy SILT (ML) CLAYSTONE PAVING AND BASE MATERIALS

Fat CLAY (CH) Silty SAND (SM) SILTSTONE CONCRETE

Sandy CLAY (CL) SAND with Silt SANDSTONE GRAVEL (GP and GW)(SP-SM and SW-SM)

SILT (ML) SAND (SP and SW) VOLCANIC GRAVEL with Sand (GP and GW)

Elastic SILT (MH) Clayey SAND (SC) DOLOMITIC SAND with Gravel (SP and SW)

Clayey SILT (ML) SAND with Clay SILICEOUS SAND with Silt and Gravel (SP-SC and SW-SC) (SP-SM and SW-SM)

Clayey GRAVEL (GP and GW) Silty SAND with Gravel (SM)

Clayey SAND with Gravel (SC)

Other Symbols

GroundwaterStrata break

PLATE A-3

MATERIAL SYMBOLS AND CLASSIFICATIONS

SUMMARY OF TERMS AND SYMBOLS

USED ON LOGS

SUMMARY OF SAMPLING DETAILS

SymbolSample

NumberSampler Type Blowcount Information


PLATE A-4

Summary of Rock Logging Descriptions

Weathering for Intact Rock (after USBR 2001)

Rock Hardness (after USBR 2001)

SUMMARY OF ROCK TERMS

USED ON LOGS

APPENDIX B

Project No. 014.002

Cu

Cc

LOCATION DH-1DEPTH 25'

PLATE B-1a

GRAINSIZE DISTRIBUTION



CLASSIFICATION


18

Cannon

Silty SAND (SM)PASSING NO. 200 (%)

0

10

20

30

40

50

60

70

80

90

100

0.0010.0100.1001.00010.000100.000GRAINSIZE (mm)

PERC

ENT

FINE

R BY

WEI

GHT

US STD SIEVE SIZE INCHES US STD SIEVE SIZE NUMBERS

SILT or CLAYSANDGRAVEL

Coarse Fine Coarse FineMedium

3 1.5 3/4 3/8 4 10 20 40 100 200

Project No. 014.002

Cu

Cc

LOCATION DH-2DEPTH 2.5'

PLATE B-1b

OAKRIDGE GEOSCIENCE, INC.Cannon

GRAINSIZE DISTRIBUTIONDE LA GARRIGUE AND RICE BRIDGE REPLACEMENT PROJECT


CLASSIFICATION PASSING NO. 200 (%)Clayey SAND (SC) 44

0

10

20

30

40

50

60

70

80

90

100

0.0010.0100.1001.00010.000100.000GRAINSIZE (mm)

PERC

ENT

FINE

R BY

WEI

GHT




3 1.5 3/4 3/8 4 10 20 40 100 200

Project No. 014.002

Cu

Cc

LOCATION DH-2DEPTH 10'

PLATE B-1c

OAKRIDGE GEOSCIENCE, INC.Cannon

GRAINSIZE DISTRIBUTIONDE LA GARRIGUE AND RICE BRIDGE REPLACEMENT PROJECT


CLASSIFICATION PASSING NO. 200 (%)Clayey SAND (SC) 42

0

10

20

30

40

50

60

70

80

90

100

0.0010.0100.1001.00010.000100.000GRAINSIZE (mm)

PERC

ENT

FINE

R BY

WEI

GHT




3 1.5 3/4 3/8 4 10 20 40 100 200

CannonProject No. 014.002 OAKRIDGE GEOSCIENCE, INC.

MAXIMUM UNIT OPTIMUM WATERLOCATION: DH-1 CLASSIFICATION DRY WEIGHT (pcf) CONTENT (%)DEPTH: 0 - 5' Sandy CLAY (CL) 128 10

PLATE B-2a

COMPACTION TEST RESULTSDE LA GARRIGUE AND RICE BRIDGE REPLACEMENT PROJECT


110

120

130

140

2% 6% 10% 14% 18% 22% 26% 30%

Dry

Uni

t Wei

ght

(lbs/

ft3 )

Water Content (%)

Compaction Curve

ZAV Curve (Gs=2.7)

CannonProject No. 014.002 OAKRIDGE GEOSCIENCE, INC.

MAXIMUM UNIT OPTIMUM WATERLOCATION: DH-2 CLASSIFICATION DRY WEIGHT (pcf) CONTENT (%)DEPTH: 0 - 5' Sandy CLAY (CL) 128 10

PLATE B-2b

COMPACTION TEST RESULTSDE LA GARRIGUE AND RICE BRIDGE REPLACEMENT PROJECT


110

120

130

140

2% 6% 10% 14% 18% 22% 26% 30%

Dry

Uni

t Wei

ght

(lbs/

ft3 )

Water Content (%)

Compaction Curve

ZAV Curve (Gs=2.7)

Project Name Project No.Tested By Testing Date

Boring No. DH-1 Sample No. -- Depth (ft) 0-5 Soil Description

Moisture Tin ID: Tin Mass (g) Moist Soil + Tin (g) Dry Soil + Tin (g) Ring Height (in.) Ring Diameter (in.) Ring Mass (g) Ring + Soil Mass (g)

Date Remarks12/27/18 No Water12/31/18 Water

WaterWaterWaterWater

12/31/18 Final

Moisture Content Dry Unit Weight (pcf) Saturation Expansion Index

PLATE B-3

51.0% 98.9%78

10.4% 24.7%108.5 100.7

Molding After Soaking

2:37PM 0.0781

RESULTS

1.000 --

1:15PM 0.0781

4.000 --200.76 --596.1

DIAL READINGSTime Reading

1:08PM 0.0001

102.78 704.35248.56 833.83234.79 808.2

Sandy fat CLAY (CH): brown, moist

Molding After SoakingST-51 T-18

TEST DATA

ND 12/27/18

SPECIMEN ID AND CLASSIFICATION

DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERINGExpansion IndexTest Method: ASTM D4829

Rice and DLG Bridges 014.002

CTL # Date: PJClient: Project:

Remarks:

Chloride pH Sulfide Moisture

As Rec. Min Sat. mg/kg mg/kg % Qualitative At Test

Dry Wt. Dry Wt. Dry Wt. EH (mv) At Test by Lead %

Boring Sample, No. Depth, ft. ASTM G57 Cal 643 ASTM G57 ASTM D4327 ASTM D4327 ASTM D4327 ASTM G51 ASTM G200 Temp °C Acetate Paper ASTM D2216

DH-1 1 0-5 - - 1,267 3 103 0.0103 7.5 - - - 17.5 Dark Yellowish Brown Sandy CLAY

DH-2 1 0-5 - - 2,135 <2 128 0.0128 7.7 - - - 10.3 Reddish Brown Sandy CLAY

PLATE B-4

Corrosivity Tests Summary

(Redox)

PJ014-002

Resistivity @ 15.5 °C (Ohm-cm)

Proj. No:

Checked:1/3/19Oakrdige Geoscience

Soil Visual Description

903-053Rice DLG Bridges

Sample Location or ID Sulfate ORP

Tested By:

GEOTECHNICAL REPORT DE LA GARRIGUE AND RICE BRIDGE ...

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