Copyright © 2025 by ENGEO Incorporated. This document
may not be reproduced in whole or in part by any means
whatsoever, nor may it be quoted or excerpted without the express written consent of ENGEO Incorporated.
10857 LINDA VISTA DRIVE
CUPERTINO, CALIFORNIA
DESIGN-LEVEL GEOTECHNICAL EXPLORATION
SUBMITTED TO
Mr. Austin Lin
SummerHill Homes
3000 Executive Parkway, Suite 450
San Ramon, CA 94583
PREPARED BY
ENGEO Incorporated
May 2, 2025
PROJECT NO.
25712.000.001
GEOTECHNICAL
ENVIRONMENTAL
WATER RESOURCES
CONSTRUCTION SERVICES
COASTAL/MARINE GEOTECHNICS
2350 Mission College Boulevard, Suite 800 Santa Clara, CA 95054 (408) 574-4900 [email protected] www.engeo.com
Project No.
25712.000.001
May 2, 2025
Mr. Austin Lin
SummerHill Homes
3000 Executive Parkway, Suite 450
San Ramon, CA 94583
Subject: 10857 Linda Vista Drive
Cupertino, California
DESIGN-LEVEL GEOTECHNICAL EXPLORATION
Dear Mr. Lin:
ENGEO prepared this design-level geotechnical report for the 10857 Linda Vista Drive project, as outlined in our agreement dated April 2, 2025. We characterized the subsurface conditions at the site to provide the enclosed geotechnical recommendations for design.
Our experience and that of our profession clearly indicate that the risk of costly design, construction, and maintenance problems can be significantly lowered by retaining the design geotechnical engineering firm to review the project plans and specificati ons and provide geotechnical testing and observation services during construction. Please let us know when working drawings are nearing completion and we will be glad to discuss these additional services with you.
If you have any questions or comments regarding this report, please call and we will be glad to discuss them with you.
Sincerely,
ENGEO Incorporated
Lauren Loey, PE Robert H. Boeche, CEG
lebl/jtr/rhb/cb
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TABLE OF CONTENTS
LETTER OF TRANSMITTAL
1.0 INTRODUCTION .................................................................................................. 1
1.1 PURPOSE AND SCOPE ................................ ................................ ................................ 1
1.2 PROJECT LOCATION ................................ ................................ ................................ .... 1
1.3 PROPOSED DEVELOPMENT ................................ ................................ ........................ 1
2.0 FINDINGS ............................................................................................................ 2
2.1 SITE HISTORY ................................ ................................ ................................ .............. 2
2.2 GEOLOGY AND SEISMICITY ................................ ................................ ........................ 3
2.2.1 Regional Geology ................................ ................................ .............................. 3
2.2.2 Seismicity ................................ ................................ ................................ .......... 3
2.3 PREVIOUS FIELD EXPLORATIONS ................................ ................................ .............. 4
2.3.1 ENGEO. 2024a. Preliminary Geotechnical Exploration. ................................ ...... 4
2.3.2 ENGEO. 2024b. Fault Exploration. ................................ ................................ ..... 5
2.4 CURRENT FIELD EXPLORATION ................................ ................................ ................. 5
2.5 SURFACE CONDITIONS ................................ ................................ ............................... 6
2.6 SUBSURFACE CONDITIONS ................................ ................................ ........................ 6
2.7 GROUNDWATER CONDITIONS ................................ ................................ .................... 6
2.8 LABORATORY TESTING ................................ ................................ ............................... 6
2.9 SLOPE STABILITY ANALYSES ................................ ................................ ..................... 7
2.9.1 Method of Analysis ................................ ................................ ............................. 7
2.9.2 Acceptable Factors of Safety ................................ ................................ .............. 7
2.9.3 Geometry and Idealized Soil Profiles ................................ ................................ .. 7
2.9.4 Results of Analyses................................ ................................ ............................ 8
2.10 LIQUEFACTION ANALYSIS ................................ ................................ ........................... 8
2.11 DYNAMIC DENSIFICATION SETTLEMENT ................................ ................................ ... 9
3.0 CONCLUSIONS ................................................................................................... 9
3.1 EXISTING FILL ................................ ................................ ................................ .............. 9
3.2 SEISMIC HAZARDS ................................ ................................ ................................ ....... 9
3.2.1 Ground Rupture ................................ ................................ ............................... 10
3.2.2 Ground Shaking ................................ ................................ ............................... 10
3.2.3 Liquefaction ................................ ................................ ................................ ..... 10
3.2.4 Dynamic Densification ................................ ................................ ...................... 10
3.2.5 Lateral Spreading ................................ ................................ ............................. 10
3.3 2022 CBC SEISMIC DESIGN ................................ ................................ ....................... 11
3.4 SOIL CORROSION POTENTIAL ................................ ................................ .................. 11
3.5 STATIC SETTLEMENT ................................ ................................ ................................ 12
4.0 CONSTRUCTION MONITORING ...................................................................... 13
5.0 EARTHWORK RECOMMENDATIONS.............................................................. 13
5.1 DEMOLITION AND SITE PREPARATION ................................ ................................ .... 13
5.2 EXISTING FILL REMOVAL ................................ ................................ .......................... 14
5.3 SOIL MOISTURE CONDITIONS ................................ ................................ ................... 14
5.4 ACCEPTABLE FILL ................................ ................................ ................................ ...... 14
5.5 FILL PLACEMENT ................................ ................................ ................................ ....... 14 SummerHill Homes 10857 Linda Vista Drive
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5.5.1 Structural Areas ................................ ................................ ............................... 14
5.5.2 Landscape Areas ................................ ................................ ............................. 15
5.6 SITE DRAINAGE ................................ ................................ ................................ .......... 15
5.6.1 Surface Drainage ................................ ................................ ............................. 15
5.6.2 Stormwater Bioretention Areas ................................ ................................ ......... 15
6.0 FOUNDATION RECOMMENDATIONS – RESIDENTIAL STRUCTURES ........ 16
6.1 POST-TENSIONED MAT FOUNDATIONS ................................ ................................ ... 16
6.1.1 Slab Moisture Vapor Reduction ................................ ................................ ........ 17
7.0 FOUNDATION RECOMMENDATIONS – ANCILLARY STRUCTURES ........... 17
7.1 CONVENTIONAL FOOTINGS ................................ ................................ ...................... 18
7.1.1 Footing Dimensions and Allowable Bearing Capacity ................................ ....... 18
7.1.2 Foundation Lateral Resistance ................................ ................................ ......... 18
7.2 HELICAL PILES ................................ ................................ ................................ ........... 18
7.2.1 Construction Considerations ................................ ................................ ............ 19
8.0 SLABS-ON-GRADE ........................................................................................... 19
8.1 EXTERIOR FLATWORK................................ ................................ ............................... 19
8.2 TRENCH BACKFILL ................................ ................................ ................................ ..... 19
9.0 RETAINING WALLS .......................................................................................... 20
9.1 LATERAL SOIL PRESSURES ................................ ................................ ...................... 20
9.2 RETAINING WALL DRAINAGE ................................ ................................ .................... 20
9.3 BACKFILL ................................ ................................ ................................ .................... 20
9.4 FOUNDATIONS ................................ ................................ ................................ ........... 21
10.0 PAVEMENT DESIGN ......................................................................................... 21
10.1 PRELIMINARY FLEXIBLE PAVEMENTS ................................ ................................ ..... 21
10.2 RIGID PAVEMENTS................................ ................................ ................................ ..... 21
10.3 SUBGRADE AND AGGREGATE BASE COMPACTION ................................ ............... 22
10.4 CUTOFF CURBS ................................ ................................ ................................ ......... 22
11.0 LIMITATIONS AND UNIFORMITY OF CONDITIONS ....................................... 22
SELECTED REFERENCES
FIGURES
APPENDIX A – Boring Logs
APPENDIX B – Laboratory Test Data
APPENDIX C – Previous Explorations (ENGEO)
APPENDIX D – Slope Stability Analysis
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1.0 INTRODUCTION
1.1 PURPOSE AND SCOPE
ENGEO prepared this geotechnical report for the design of the 10857 Linda Vista Drive project in Cupertino, California. As outlined in our agreement dated April 4, 2025, you authorized ENGEO to conduct the following scope of services.
• Subsurface field exploration
• Soil laboratory testing
• Data analysis and conclusions
• Report preparation
For our use, we received a preliminary grading plan (Sheet C4.0) and preliminary grading sections (Sheet C4.1) prepared by CBG for SummerHill Homes, dated February 3, 2025.
In 2024, we prepared a Preliminary Geotechnical Exploration Report (ENGEO, 2024a) and a Fault Exploration (ENGEO, 2024b) for the subject site.
This report was prepared for the exclusive use of SummerHill Homes, and its consultants, for design of this project. In the event that any changes are made in the character, design, or layout of the development, we must be contacted to review the conclusions and recommendations contained in this report to evaluate whether modifications are recommended. This document may not be reproduced in whole or in part by any means whatsoever, nor may it be quoted or excerpted without our express written consent.
1.2 PROJECT LOCATION
The approximately 2½ -acre site is identified by the Assessor’s Parcel Numbers (APNs) 356-06-001, 356 -06-002, 356 -06-003, and 356 -06-004. The site is located at 10857 -10887 Linda Vista Drive in Cupertino, California, as shown in the Vicinity Map (Figure 1). The site is bounded by the Cupertino Hills Swim and Racquet Club to the north, residential development to the south, Linda Vista Drive to the east, and the Deep Cliff Golf Course to the west. The western boundary of the site sits atop an approximately 2½:1 (horizontal:vertical) slope that is approximately 50 feet in height sloping down towards the Deep Cliff Golf Course.
The site currently consists of four single-family residential homes with five auxil iary structures.
The Site Plan (Figure 2) shows the boundary of the project site and the approximate locations of our explorations.
1.3 PROPOSED DEVELOPMENT
Based on our conversation with you and our review of the project documents, we understand site improvements will include the following.
• Ten townhome structures with a total of 51 dwelling units up to three stories in height • Underground utilities
• Sidewalks
• Landscaped areas, including bioretention areas
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• Paved Streets
• Site walls and retaining walls
Preliminary grading plans show grading will be limited to minor cut and fill (up to 4 feet), with a retaining wall along the western boundary with a maximum retained heigh t of 4 feet. We understand the proposed single-family structures will be at-grade and of conventional wood-frame construction. Structural loading information is not available at the time of this report writing . We assume building loads will be typical for this construction type.
2.0 FINDINGS
2.1 SITE HISTORY
To understand site development history and geomorphology, we reviewed historical aerial photographs and topographic maps. We viewed numerous historical aerial photographs from 1948 through 202 5 available on Google Earth, www.historicaerials.com, Environmental Data Resources (EDR), Frame Finder – UCSB Library, and NGMDB (USGS/AASG). We also viewed historical topographic maps dat ing back to 1897 to understand the site history before aerial photographic coverage was available. Topographic maps show the site’s ground surface between approximately Elevation 400 feet and 375 feet (datum unknown), with no evidence of major topographic changes since early mapping. Our observations are summarized below in chronological order.
At least late 1890s to early 1980s: The topographic map s from 1897 and 190 2 show no structures or roads mapped within the site (Exhibit 2.1 -1, A - 1897). By the 19 48 aerial photograph, structures were still not present within the site, and no roads were visible. The site and surrounding area appear to have been used for agricultural cultivation, specifically orchards (Exhibit 2.1 -1, B - 1948). By 1953, two residential structures were buil t along the northern boundary of the site (10857 and 10867 Linda Vista Drive) (Exhibit 2.1-1, C - 1965). The southern portions of the site are still being utilized for orchards at this time, and other residential houses were developed to the south of the site.
1980s through mid-1990s: The structure at 10887 Linda Vista Drive was built by 1968 and 10877 Linda Vista Drive by 1982 and the orchard within the southern portions of the site w as removed (Exhibit 2.1-1, D - 1991). The area surrounding the site continued to be developed with more residential structures (generally to the south, east, and north). Some trees are present within the site in landscaped areas.
Early 1990s to Present: The current site conditions generally remain unchanged from 1991 to present day.
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EXHIBIT 2.1-1: Topographic Maps and Aerial Photographs
A - 1897 B - 1948 C - 1965
D -1991 E - 2002 F - 2020
2.2 GEOLOGY AND SEISMICITY
2.2.1 Regional Geology
The site is located within the Coast Ranges geomorphic province of California. The Coast Ranges province is typified by a system of northwest -trending, fault -bounded mountain ranges and intervening alluvial valleys. Bedrock in the Coast Ranges consists of igneous, metamorphic, and sedimentary rocks that range in age from Jurassic to Pleistocene. The present physiography and geology of the Coast Ranges are the result of deformation and deposition along the tectonic boundary between the North American plate a nd the Pacific plate. Plate boundary fault movements are largely concentrated along the well-known fault zones, which in the area include the San Andreas, Hayward, and Calaveras faults, as well as other lesser-known faults.
According to regional mapping by Brabb et al. (2000, Figure 3), the site is underlain primarily by Pleistocene alluvial fan and fluvial deposits and lies just northeast of the Monte Vista -Shannon Fault zone. Dibblee (2007) mapped the site as being primarily underlain by Quaternary aged older surficial sediments deri ved from hills to the west comprised of Santa Clara Formation and Franciscan Formation bedrock.
2.2.2 Seismicity
The San Francisco Bay Area contains numerous active faults. An active fault is defined by the California Geologic Survey as one that has had surface displacement within Holocene time (about the last 11,700 years) (CGS, 2018). Numerous small earthquakes occur every year in the San Francisco Bay Region, and larger earthquakes have been recorded and can be expected
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to occur in the future. Figure 4 shows the approximate locations of these faults and significant historic earthquakes recorded within the San Francisco Bay Region. The site is not located within a currently designated Alquist -Priolo Earthquake Fault Zone. However, the site is located in a Santa Clara County Fault Rupture Hazard Zone (2012, Figure 6) associated with the Monte Vista-Shannon fault.
The site is within a seismically active region. To identify nearby active faults that can generate strong seismic ground shaking at the site, we utilized the USGS Earthquake Hazard Toolbox and the 2018 National Seismic Hazard Model (NSHM) to perform a disaggregation of the hazard at the peak ground acceleration (PGA) for a 2,475-year return period, with the resulting faults listed below in Table 2.2.2-1.
TABLE 2.2.2-1: Active Faults Capable of Producing Significant Ground Shaking at the Site (Latitude: 37.31014 Longitude: -122.06033)
FAULT NAME
RUPTURE DISTANCE, RRUP MOMENT MAGNITUDE
(MW) KILOMETERS MILES
Monte Vista-Shannon (3) 1.8 1.1 7.2
Monte Vista-Shannon (4) 1.9 1.2 6.7
San Andreas (Peninsula) (2) 6.0 3.7 7.8
San Andreas (Peninsula) (1) 6.4 4.0 7.4
Monte Vista-Shannon (3) 6.7 4.2 6.6
San Andreas (Santa Cruz Mountains) (0) 15.9 9.9 7.2
Hayward (South) (1) 23.0 14.3 7.3
* Based on USGS Earthquake Hazard Toolbox: NSHM Conterminous U.S. 2018
These results represent known fault sources contributing at least 1 percent to the seismic hazard in our disaggregation. The rupture distances (RRUP) and mean moment magnitudes (MW) listed are based on values assigned according to the 2018 NSHM, and the numbers in parentheses after the fault names correspond to fault subsections assigned by the NSHM. Note that the above fault table is not an exhaustive list and other faults in the region may generate seismic shaking at the project site.
The Uniform California Earthquake Rupture Forecast (UCERF3) (Field et al, 2015) estimates the 30-year probability for a magnitude 6.7 or greater earthquake in Northern California at approximately 95 percent, considering the known active seismic sources in the region.
2.3 PREVIOUS FIELD EXPLORATIONS
2.3.1 ENGEO. 2024a. Preliminary Geotechnical Exploration.
As mentioned in Section 1.1, we previously prepared a preliminary geotechnical exploration at the subject site for the current project. We retained the services of a licensed C -57 contractor operating a truck-mounted cone penetration test (CPT) rig to advance CPTs at the four locations shown in Figure 2. The CPTs were performed in general accordance with ASTM D5778.
Measurements include the tip resistance to penetration of the cone (Qc), the resistance of the friction sleeve (Fs), and pore pressure (U) (Robertson and Campanella, 1988). The CPTs were advanced to practical refusal ranging between approximate depths of 9 feet to 58 ½ feet below ground surface ( bgs). Pore pressure dissipation tests were performed at three CPT locations; none encountered groundwater.
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The contractor performed shear -wave velocity (VS) measurements in 1 -CPT1 using procedures in general accordance with ASTM D5778 and ASTM D7400. We present the CPT logs and the VS profile in Appendix B.
We incorporated the data from this previous exploration into our analysis and findings of this report.
2.3.2 ENGEO. 2024b. Fault Exploration.
We previously prepared a fault exploration report for the subject property which involved excavating three fault trenches in the southeastern portion of the site to evaluate the potential for surface fault rupture at the site and within the proposed development areas. The trenches were excavated along a roughly east -northeast trend to be perpendicular to the mapped trace of the Monte Vista-Shannon Fault, as shown in Figure 2 . The trenches extended to a maximum depth of 10 feet bgs and constituted roughly 280 linear feet of excavation. We encountered older alluvial deposits consistent with the geologic maps and previous studies.
We found no evidence of a surface fault rupture within our trenches across the project site and our study found no evidence to suggest that the Monte Vista-Shannon Fault is present at the site.
We present the trench logs in Appendix B. We incorporated the data from this previous exploration into our analysis and findings of this report.
2.4 CURRENT FIELD EXPLORATION
Our current field exploration included drilling three borings at various locations on the site. We performed our field exploration on April 3, 2025. The approximate locations of our borings are shown in Figure 2.
We estimated the locations of our explorations using consumer -grade global positioning system (GPS) and their proximity to existing site features; therefore, the locations shown should be considered accurate only to the degree implied by the method used. W e permitted our explorations with Valley Water (formerly Santa Clara Valley Water District).
We retained the services of a drilling subcontractor who provided a crew operating a truck-mounted drill rig to advance the borings using 4 -inch-diameter solid-flight-auger and mud rotary drilling methods. We advanced the borings to depths ranging from approximately 30 to 48 feet bgs. A representative of our firm observed the drilling and logged the subsurface conditions at each location.
We obtained soil samples at various depth intervals using either standard penetration test (SPT) samplers with a 2 -inch outside diameter (O.D.) split -spoon sampler or California Modified samplers with 2½-inch inside diameter (I.D.) fitted with sampling liners. We advanced the driven samplers with an automatic trip, 140 -pound hammer with a 30 -inch free fall and recorded the penetration of the sampler in the field as the number of blows needed to drive the sampler 18 inches in 6-inch increments. The boring lo g shows the number of blows required for the last 1 foot of penetration, or the number of blows per depth of penetration for samples that met driving refusal. We did not adjust the blow counts shown in the boring logs using any energy correction or sample size factors.
The boring logs are presented in Appendix A. The logs depict interpreted subsurface conditions within the borings at the time the exploration was conducted. The stratification lines in our logs SummerHill Homes 10857 Linda Vista Drive
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represent the approximate boundaries between soil types and the actual material transitions may be more gradual. Subsurface conditions at other locations may differ from the conditions noted at these boring locations.
2.5 SURFACE CONDITIONS
There was no appreciable difference at the project site between our current exploration in April 2025 and our previous exploration in August 2024. The surface conditions at the site generally consisted of residential structures and vegetated areas. Site grades r ange from Elevation 391 in the northeast to Elevation 397 in the southwest (NAVD88). The site is generally flat with a gentle slope from west to east. The western boundary of the site sits atop an approximately 2½:1 (horizontal:vertical) slope that is approximately 50 feet in height.
Approximately 8 feet below the top of the slope is a bench that makes up the existing Stevens Creek Trail. The bench is approximately 8½ feet wide and ranges in elevation from Elevation 388 feet in the south and Elevation 389½ feet in the north as the trail parallels the project site boundary.
Please refer to the Site Plan, Figure 2, for more information on site features.
2.6 SUBSURFACE CONDITIONS
Based on our interpretation of the CPT data , fault trenches, and borings , the subsurface conditions at the site generally consist of loose to medium dense clayey sand and stiff to very stiff lean clay in the upper 3 to 7 feet of the site, underlain by medium dense to very dense poorly graded sand with clay, clayey gravel, and clayey sand with interbedded lenses of very stiff to hard fine-grained material and dense to very dense silty sand to the maximum depth explored of 58½ feet bgs. As noted in the fault evaluation, deposits encountered were consistent with Pleistocene age deposits.
The results of our plasticity index (PI) testing for materials near the ground surface between 1 and 2½ feet yielded PI results ranging from 10 to 11, which indicates low expansion potential.
2.7 GROUNDWATER CONDITIONS
Based on equilibrium pore pressure not being achieved in our CPT pore pressure dissipation tests, we conclude that we did not observe static groundwater in our explorations, which extended to a maximum depth of approximately 58 feet. The Seismic Hazard Zone Report for the Cupertino quadrangle reports a historical high groundwater depth of greater than approximately 50 feet below the ground surface for the site (CGS, 2002).
Fluctuations in groundwater levels should be expected during seasonal changes or over a period of years because of precipitation changes, perched zones, and changes in irrigation and drainage patterns.
2.8 LABORATORY TESTING
We performed laboratory tests on selected soil samples to evaluate their engineering properties.
For this project, we performed moisture content, plasticity index, gradation, hydrometer, and soil corrosion potential testing. Moisture content , fines content, and plasticity index results are recorded in the boring logs in Appendix A; other laboratory data is included in Appendix B.
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2.9 SLOPE STABILITY ANALYSES
2.9.1 Method of Analysis
Geotechnical evaluation of slope stability involves assessment of the input parameters along with the selected method of analysis. While there are many different methods of stability analysis and numerous available computer programs, we selected the program SLIDE2, by Rocscience.
SLIDE2 is a two -dimensional limit equilibrium program that is widely used in slope stability evaluations. We used Spencer’s Method, which is an iterative solution that satisfies b oth force and moment equilibrium and assumes all slice side forces have the same inclination. This method is appropriate for both circular and non-circular failure surfaces; for this evaluation, we considered only circular failure surfaces.
In evaluating the stability of slopes under seismic conditions, we used a “pseudostatic” method of analysis. This has been a common method of evaluating the stability of engineered slopes during earthquakes. The pseudostatic method models the effects of transient or pulsating earthquake loading on a potential slide mass by using an equivalen t sustained horizontal force that is the product of a seismic coefficient and the weight of the potential slide mass. The slope is first analyzed to establish the minimum factor of safety under static conditions. Once this critical failure surface is locat ed, an additional horizontal force acting in the direction of potential failure is imposed on the sliding mass. This additional force is equal to the soil mass multiplied by a seismic coefficient of horizontal acceleration.
For most pseudostatic stability analyses in the United States, a design seismic coefficient on the order of 0.05 g to 0.15 g has typically been used, where “g” is the ground acceleration expressed in terms of the equivalent acceleration due to Earth’s grav ity. Using the procedure outlined in Special Publication 117A (California Geological Survey, Guidelines for Evaluating and Mitigation Seismic Hazards in California, 2008) and based on the maximum considered earthquake geometric mean peak ground acceleration (PGAm) from the 2022 California Building Code (CBC), a moment magnitude of 7.9 based on an earthquake on the San Andreas Fault, we obtained and used a seismic coefficient (Kh) of 0.34 g for our analysis using the 15-centimeter threshold.
2.9.2 Acceptable Factors of Safety
Based on local geotechnical practice, in our opinion, we recommend that a static factor of safety of 1.5 and a pseudostatic factor of safety of 1.0 be considered adequate for the proposed slopes.
We considered the various levels of conservatism involved in determining the engineering properties of the soil (density, shear strength, unit weight, etc.), the assumptions made in the method of analysis, and potential variations in field conditions.
2.9.3 Geometry and Idealized Soil Profiles
We reviewed the proposed preliminary grading plans to identify critical cross-sections to analyze for slope stability. We selected one cross section (A -A’) at the steepest grade of the adjacent slope. The location of the analyzed Cross Section A-A’ is shown in the Site Plan, Figure 2.
We developed an idealized profile representative of the anticipated subsurface conditions and proposed slope configurations at the cross-section location . For modeling the planned improvements, we referenced the proposed development plan for retaining wall location and building footprints. We applied surcharge loads at the proposed building footing print and roadways based on the development plan. Cross Section A-A’ is shown in Appendix D.
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To develop our shear strength parameters, we used the subsurface information obtained from our field exploration, laboratory test results, and engineering judgement . We also referred to shear strength parameters for geologic units presented in the Seismic Hazard Zone report for the Cupertino quadrangle (CGS, 2002). Based on our review of the data and our experience , we selected the following parameters to represent lower -bound shear strengths for the native geologic units used in our slope stability models.
TABLE 2.9.3-1: Strength Parameters for Slope Stability Analysis
MATERIAL UNIT WEIGHT
(pcf)
COHESION
(psf)
PHI
(degrees)
Surficial deposits – Lean Clay and Clayey Sand 120 150 28 Pleistocene Deposits – Poorly Graded Sand with Low
Fines Content 120 100 35
Pleistocene Deposits – Clayey Gravel and Clayey Sand 120 200 38 Pleistocene Deposits – Silt and Lean Clay 120 200 28
2.9.4 Results of Analyses
We performed slope stability analyses for both static and pseudostatic conditions. The results of our analyses are summarized in the table below and are included in Appendix D.
TABLE 2.9.4-1: Summary of Slope Stability Analyses
FACTOR OF SAFETY
LOCATION STATIC PSEUDOSTATIC
(0.31g)
Cross-Section A-A’ 1.5 1.0
2.10 LIQUEFACTION ANALYSIS
According to the Seismic Hazard Zones Map for the Cupertino Quadrangle (CGS, 2002) the site is not located within a liquefaction hazard zone. However, the CGS (2002) and Santa Clara County (SCC, 2012) Santa Clara County Hazard Zones (SCC, 2012) (Figure 6), identify the property immediately west of the project site as an area that lies within a liquefaction hazard zone, as shown in Figure 5. Note that the Seismic Hazard Zone Maps provide potential liquefaction risks based on general geologic conditions.
Soil liquefaction results from loss of strength during cyclic loading, such as imposed by earthquakes. The soil considered most susceptible to liquefaction is clean, loose, saturated, and uniformly graded fine sand below the groundwater table. Empirical evidence indicates that loose silty sand is also potentially liquefiable. When seismic ground shaking occurs, the soil is subjected to cyclic shear stresses that can cause excess hydrostatic pressures to develop. If excess hydrostatic pressures exceed the ef fective confining stress from the overlying soil, it is said to have liquefied. If the sand consolidates or vents to the surface during and following liquefaction, ground settlement, and surface deformation may occur. In addition to liquefaction of sandy materials, clayey soil can also undergo “cyclic softening” or strength loss as a result of cyclic loading.
We encountered medium dense to very dense sand in our CPTs and borings. Laboratory testing on samples collected from the borings revealed appreciable fines content in the sand. We did not encounter groundwater in our subsurface explorations, and the historic depth to groundwater at SummerHill Homes 10857 Linda Vista Drive
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the site is over 50 feet below ground surface (CGS 2002) . Therefore, we conclude the risk of liquefaction at the site is low.
2.11 DYNAMIC DENSIFICATION SETTLEMENT
Dynamic densification settlement of loose granular soil above the groundwater table, also called dry-sand settlement, can cause settlement of the ground surface due to earthquake -induced vibrations. Dynamic densification is generally a higher risk for sand or gravel with fines contents less than 15 percent. Our previous C PT-based analysis of potential dynamic densification settlement for sand layers above the groundwater table indicated up to 1 inch of settlement at the site, with most densification settlement occurring within a fine-grained to silty sand lens at depths of approximately 24 to 28 feet below ground surface. However, our boring explorations and laboratory testing revealed the subsurface conditions at these depths at the site have higher fines contents than previously shown in the CPTs. We evaluated the dynamic-densification potential of sandy layers with fines content less than 15 percent using the procedures outlined in Tokimatsu and Seed (1987) and Robertson and Shao (2010). B ased on our analy sis, we estimate up to ½ inch of dry-sand densification is possible under the maximum considered earthquake (MCE G) seismic event.
3.0 CONCLUSIONS
From a geotechnical engineering viewpoint, in our opinion, the site is suitable for the proposed development, provided the geotechnical recommendations in this report are properly incorporated into the design plans and specifications, and finalized with additional explorations.
The primary geotechnical concerns that could affect development on the site are existing fill, expansive soil, and seismically induced settlement (i.e., dry sand settlement). We summarize our conclusions below.
3.1 EXISTING FILL
Our borings encountered approximately 1½ feet of fill across the site. This depth of fill is consistent with typical depth of disturbance associated with orchards , which were present at the site.
Non-engineered fill is also possible to exist around existing structures and in-place improvements, such as abandoned septic systems.
Existing, non -engineered fill may undergo excessive settlement, especially under new fill or building loads. Without proper documentation of the existing fill placed on the site, we recommend complete removal and recompaction of the existing fill. We anticipate manmade debris within the existing fill can be selectively removed from the material before reuse as en gineered fill. We present fill removal recommendations in Section 5.2.
3.2 SEISMIC HAZARDS
Potential seismic hazards resulting from a nearby moderate to major earthquake can generally be classified as primary and secondary. The primary effect is ground rupture, also called surface faulting. The common secondary seismic hazards include ground shaking and liquefaction. Based on site observations, topographic and lithologic data, subsurface data, and regional geology, the risk of regional subsidence or uplift, landslides, tsunamis, or seiches are considered low to negligible at the site.
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The following sections present a discussion of select seismic hazards as they apply to the site.
3.2.1 Ground Rupture
The site is located within a Santa Clara County Fault Rupture Hazard Zone, as shown in Figure 6.
According to USGS (2022), the Monte Vista-Shannon fault zone is located less than ¼ mile east and west of the project site. We performed a fault trench study ( ENGEO, 2024b) to evaluate possible ground rupture. Based on our findings, the risk of ground rupture within the site is low.
3.2.2 Ground Shaking
An earthquake of moderate to high magnitude generated within the region could cause considerable ground shaking at the site, similar to that which has occurred in past major events.
To mitigate the effects of ground shaking, all structures should be designe d using sound engineering judgment and in accordance with the latest edition of the California Building Code (CBC), as a minimum.
Seismic design provisions of current building codes generally prescribe minimum lateral forces, applied statically to the structure, combined with the gravity forces of dead and live loads. The code-prescribed lateral forces are generally considered to be substantially smaller than the actual forces that would be associated with a major earthquake. Therefore, structures should be able to:
(1) resist minor earthquakes without damage, (2) resist moderate earthquakes without structural damage, but with some non-structural damage, and (3) resist major earthquakes without collapse, but with some structural, as well as non-structural damage. Conformance to the current building code recommendations does not constitute any kind of guarantee that significant structural damage would not occur in the event of a maximum magnitude earthquake; however, it is reasonable to e xpect that a well -designed and well -constructed structure will not collapse or cause loss of life in a major earthquake. Section 3.4 presents the 2022 California Building Code design parameters.
3.2.3 Liquefaction
As summarized in Section 2.10, the site does not lie within a liquefaction hazard zone, though the area immediate to the west of our site does.
Considering the granular deposits encountered in our explorations were medium dense to very dense sand and we did not encounter groundwater in our subsurface explorations , the potential for liquefaction at the site is low.
3.2.4 Dynamic Densification
As summarized in Section 2.11, medium dense to very dense granular material was encountered above the design groundwater level. Based on our analyses described in Section 2.1 1, we estimate potential dynamic densification settlements of up to ½ inch. This densification settlement should be considered in the foundation design provided in Section 6.0.
3.2.5 Lateral Spreading
Lateral spreading is a failure within a nearly horizontal soil zone (possibly due to liquefaction) that causes the overlying soil mass to move towards a free face or down a gentle slope. Generally, SummerHill Homes 10857 Linda Vista Drive
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the effects of lateral spreading are most significant at the free face or the crest of a slope and diminish with distance from the slope.
The western boundary of the site sits atop an approximately 2½:1 (horizontal:vertical) slope that is approximately 50 feet in height. However, the risk of liquefaction occurring and acting as the mechanism for lateral spread is low. Additionally, our pseudostatic slope stability analysis presented in Section 2.9 meets recommended factors of safety considering approximately 15 cm of deflection. Based on these factors, we conclude the risk of lateral spreading at the project site is low.
3.3 2022 CBC SEISMIC DESIGN
The 2022 CBC utilizes seismic design criteria established in the ASCE/SEI Standard “Minimum Design Loads and Associated Criteria for Buildings and Other Structures,” (ASCE 7-16). Based on the subsurface conditions encountered and shear -wave velocity measurements at 1 -CPT1, we characterized the site as Site Class C. In Table 3. 3-1 below, w e provide the CBC seismic parameters based on the United States Geological Survey’s (USGS’) Seismic Design Maps for your use.
TABLE 3.3-1: 2022 CBC Seismic Design Parameters, Latitude: 37.31014 Longitude: -122.06033
PARAMETER VALUE
Site Class C
Mapped MCER Spectral Response Acceleration at Short Periods, SS (g) 2.31 Mapped MCER Spectral Response Acceleration at 1-second Period, S1 (g) 0.83 Site Coefficient, Fa 1.2
Site Coefficient, Fv 1.4
MCER Spectral Response Acceleration at Short Periods, SMS (g) 2.77 MCER Spectral Response Acceleration at 1-second Period, SM1 (g) 1.16 Design Spectral Response Acceleration at Short Periods, SDS (g) 1.85 Design Spectral Response Acceleration at 1-second Period, SD1 (g) 0.78 Mapped MCE Geometric Mean (MCEG) Peak Ground Acceleration, PGA (g) 0.96 Site Coefficient, FPGA 1.2
MCEG Peak Ground Acceleration adjusted for Site Class effects, PGAM (g) 1.15 Long-period transition-period, TL 12 sec
3.4 SOIL CORROSION POTENTIAL
As part of this study, we obtained representative soil samples and submitted to Cerco Analytical, a qualified analytical lab for determination of pH, resistivity, sulfate, and chloride. The results are included in Appendix B and summarized in the table below.
TABLE 3.4-1: Corrosivity Test Results
SAMPLE
LOCATION
DEPTH
(feet) PH RESISTIVITY
(OHMS-CM)
CHLORIDE
(MG/KG)
SULFATE
(MG/KG)
REDOX
(mV)
2-B1 1 7.28 4,800 < 15 < 15 240
2-B2 1.5 7.97 5,900 < 15 <15 240
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The 2022 CBC references the 2019 American Concrete Institute Manual, ACI 318 -19, Section 19.3.1 for concrete durability requirements. ACI Table 19.3.1.1 provides exposure categories and classes, and Table 19.3.2.1 provides requirements for concrete in cont act with soil based upon the exposure class.
In accordance with the criteria presented in ACI Table 19.3.1.1, this soil is categorized as within the F0 freeze-thaw class, S0 sulfate exposure class, W0 moisture/water exposure class, and C0 corrosion class.
Considering a ‘Not Applicable’ sulfate exposure, there is no requirement for cement type or water-cement ratio; however, a minimum concrete compressive strength of 2,500 pounds per square inch (psi) is specified by the building code. For this sulfate range, we recommend Type II cement and a concrete mix design for foundations and building slabs-on-grade that incorporates a maximum water -cement ratio of 0.50. It should be noted, however, that the structural engineering design requirements for concrete may re sult in more stringent concrete specifications.
As part of their analyses, Cerco Analytical provided brief commentary based on the test results.
The full results are presented in Appendix B. We provide a summary of the commentary below.
• Based on the resistivity measurements, the soil from both samples is considered “moderately corrosive” to buried metal piping. All buried iron, steel, cast iron, ductile iron, galvanized steel and dielectric coated steel or iron should be properly protected against corrosion depending upon the critical nature of the structure. All buried metallic pressure piping, such as ductile iron firewater, should be protected against corrosion.
• The reported values of chloride, sulfate, and pH concentrations do not pose a significant impact to metal or concrete.
• The reported value for redox potential is indicative of “slightly corrosive” soil resulting from anaerobic soil conditions.
The recommendations provided are for general reference. If it is desired to investigate this further, we recommend a corrosion consultant be retained to evaluate whether specific corrosion recommendations are advised for the project.
3.5 STATIC SETTLEMENT
Soil may settle in response to new loads induced by new fill, structures, or equipment. This settlement, if it occurs, may occur as immediate (elastic) or long -term consolidation settlement.
The site is primarily underlain by medium dense to very dense sandy soil. We anticipate building loads will apply to an average bearing pressure of up to 1,000 pounds per square foot (psf).
Considering the subsurface conditions and that site grading is performed in accordance with the recommendations in Section 5, we es timate less than ½ inch of elastic settlement due to static loading, with settlement occurring almost immediately upon construction of the building foundations.
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4.0 CONSTRUCTION MONITORING
Our experience and that of o ur profession clearly indicate that the risk of costly design, construction, and maintenance problems can be significantly lowered by retaining the design geotechnical engineering firm to:
1. Review the final grading and foundation plans and specifications prior to construction to evaluate whether our recommendations have been implemented, and to provide additional or modified recommendations, as needed. This also allows us to check if any changes have occurred in the nature, design , or location of the proposed improvements and provides the opportunity to prepare a written response with updated recommendations.
2. Perform construction monitoring to check the validity of the assumptions we made to prepare this report. Earthwork operations should be performed under the observation of our representative to check that the site is properly prepared, the selected fill materials are satisfactory, and that placement and compaction of the fill have been performed in accordance with our recommendations and the project specifications. Sufficient notification to us prior to earthwork is important.
If we are not retained to perform the services described above, then we are not responsible for any party’s interpretation of our report (and subsequent addenda, letters, and verbal discussions).
5.0 EARTHWORK RECOMMENDATIONS
As used in this report, relative compaction refers to the in-place dry unit weight of soil expressed as a percentage of the maximum dry unit weight of the same soil, as determined by the ASTM D1557 laboratory compaction test procedure, latest edition. Compacted soil is not acceptable if it is unstable; it should exhibit only minimal flexing or pumping, as observed by an ENGEO representative. The term “moisture condition” refers to adjusting the moisture content of the soil by either drying if too wet or adding water if too dry. We define “structural areas” as any area sensitive to settlement of compacted soil. These areas include, but are not limited to, building pads, sidewalks, pavement areas, and retaining walls.
5.1 DEMOLITION AND SITE PREPARATION
Site development should commence with the demolition and removal of surface and subsurface improvements that are planned for removal. Areas to be developed should be cleared of surface and subsurface deleterious materials, including existing buildings and their associated foundations, slabs, buried utility and irrigation lines, pavements, debris, shrubs, and associated roots. Any existing features extending below the planned finished site grades should be demolished and backfilled with suitable material compacted to the recommendations presented in Section 5.5.
Existing vegetation and their roots should be removed from areas to receive fill or improvements.
Tree roots should be removed down to a depth of at least 3 feet below existing grade. Large vegetation and debris should be separately stockpiled from soil fi ll. Subject to approval by the landscape architect, stripping’s and organically contaminated soil can also be used in landscape areas. Organically contaminated soil that will be retained for future use in landscape areas should be stockpiled in areas where they will not interfere with grading operations.
All excavations from demolition and stripping below design grades should be cleaned to a firm undisturbed soil surface, as determined by our representative.
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5.2 EXISTING FILL REMOVAL
As discussed in previous sections, existing disturbed soil is present at the site from previous site development. At this time, we consider this fill to be undocumented, non-engineered fill.
We recommend existing fill material and any other loose/soft material beneath the proposed improvements be removed to expose native soil conditions and replaced as engineered fill under the observation of our representative. Removal of potential existing fill surrounding below -grade elements, such as existing footings and underground utilities , can likely be achieved during excavation for demolition and removal of the below -grade structures. Our representative should confirm that excavation bottoms within e xisting fill expose material that is stiff and free of deleterious matter. The base of the subexcavation should be processed, moisture conditioned, and compacted as engineered fill.
5.3 SOIL MOISTURE CONDITIONS
The contractor may encounter excessively over -optimum (wet) soil moisture conditions during winter or spring grading, during or following periods of rain. Wet soil can make proper compaction difficult or impossible.
Wet soil conditions can be mitigated by:
1. Frequent spreading and mixing during warm dry weather,
2. Mixing with drier materials,
3. Mixing with a cement product, or
4. Stabilizing with aggregate or geotextile stabilization fabric, or both.
We should be allowed to evaluate options 3 and 4 and approve the approach prior to implementation.
5.4 ACCEPTABLE FILL
On-site soil is suitable as fill material provided it is processed to remove concentrations of organic material, debris, and rock particles greater than 6 inches in maximum dimension. Oversized particles should be either removed from the fill or broken down to meet the requirement. Imported fill material should meet the above requirements and have a PI less than 12 with approximately 20 percent passing the No. 200 sieve. We should be contacted to sample and test the proposed imported fill material at least 10 days prior to delivery to the site. Environmental sampling and testing of potential import soil sources should also be submitted to us for review.
5.5 FILL PLACEMENT
5.5.1 Structural Areas
After removal and recompaction of non-engineered fill, the exposed non-yielding surface of areas to receive fill or to be left at grade should be scarified to a depth of 12 inches, moisture conditioned, and recompacted to provide adequate bonding with the initial lift of fill. The loos e lift thickness should not exceed 8 inches or the depth of penetration of the compaction equipment used, whichever is less. The following compaction control requirements should be applied to all fill, including backfill, except for landscape areas.
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TABLE 5.5.1-1: Compaction Control Requirements
FILL LOCATION
REQUIRED RELATIVE
COMPACTION*
(%)
MINIMUM
MOISTURE CONTENT
(percentage points above optimum)
General Fill 90 2
Pavement and Flatwork Aggregate Base 95 0
5.5.2 Landscape Areas
The contractor should compact the finished subgrade in landscape areas in accordance with Section 5.5.1, with a minimum relative compaction of 85 percent and at a moisture content of at least 2 percentage points above optimum.
5.6 SITE DRAINAGE
5.6.1 Surface Drainage
The project civil engineer is responsible for designing surface drainage improvements. With regard to geotechnical engineering issues, we recommend that finish grades be sloped away from buildings and pavements to the maximum extent practical. The latest C alifornia Building Code Section 1804. 4 specifies minimum slopes of 5 percent away from foundations. Where development conditions restrict meeting this slope requirement, we recommend that specific drainage requirements be developed. As a minimum, we recommend the following.
1. Discharge roof down spouts into closed conduits and direct away from foundations to appropriate drainage devices.
2. Do not allow water to pond near foundations, pavements, exterior flatwork, or site walls.
5.6.2 Stormwater Bioretention Areas
If bioretention areas are implemented, we recommend that, when practical, they be planned a minimum of 5 feet away from structural site improvements, such as buildings, streets, retaining walls, and sidewalks/driveways. When this is not practical, bioretention areas located within 5 feet of structural site improvements can either:
1. Be constructed with structural side walls capable of withstanding the loads from the adjacent improvements, or
2. Incorporate filter material compacted to between 85 and 90 percent relative compaction (ASTM D1557, latest edition) and a waterproofing system designed to reduce the potential for moisture transmission into the subgrade soil beneath the adjacent improvement.
In addition, one of the following options should be followed.
1. We recommend that bioretention design incorporate a waterproofing system lining the bioswale excavation and a subdrain, or other storm drain system, to collect and convey water to an approved outlet. The waterproofing system should cover the bioretention a rea excavation in such a manner as to reduce the potential for moisture transmission beneath the adjacent improvements.
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2. Alternatively, and with some risk of movement of adjacent improvements, if infiltration is desired, we recommend the perimeter of the bioretention areas be lined with an HDPE tree root barrier that extends at least 1 foot below the bottom of the bioretention areas/infiltration trenches.
Site improvements located adjacent to bioretention areas that are underlain by baserock, sand, or other imported granular materials, should be designed with a deepened edge that extends to the bottom of the imported material underlying the improvement.
Where adjacent site improvements include buildings greater than three stories, streets steeper than 3 percent, or design elements subject to lateral loads (such as from impact or traffic patterns), additional design considerations may be recommended. If the surface of the bioretention area is depressed, the slope gradient should follow the slope guidelines described in earlier section(s) of this document. In addition, although not recommended, if trees are to be planted within bioretention areas, HDPE Tree Boxes that extend below the bottom of the bioretention system should be installed to reduce potential impact to subdrain systems that may be part of the bioretention area design. For this condition, the waterproofing system should be connected to the HPDE Tree Box with a waterproof seal.
Given the nature of bioretention systems and possible proximity to improvements, we recommend ENGEO be retained to review design plans and provide testing and observation services during the installation of linings, compaction of the filter material, and connection of designed drains.
It should be noted that the contractor is responsible for conducting all excavation and shoring in a manner that does not cause damage to adjacent improvements during construction and future maintenance of the bioretention areas. As with any excavation adj acent to improvements, the contractor should reduce the exposure time such that the improvements are not detrimentally impacted.
6.0 FOUNDATION RECOMMENDATIONS – RESIDENTIAL
STRUCTURES
We developed structural improvement recommendations using data obtained from our field exploration, laboratory test results, and engineering analysis.
Based on our slope stability analysis in Section 2. 9, we recommend a 25 -foot setback from the top of slope for any residential dwelling units. This setback is visually presented at its approximate location in Figure 2.
6.1 POST-TENSIONED MAT FOUNDATIONS
We recommend that the proposed residential structures be supported on post-tensioned (PT) mat foundations bearing on prepared native soil or engineered fill.
The structural engineer should determine the actual PT mat thickness using the geotechnical recommendations in this report; we defer to the professional judgment of the structural engineer on the necessary mat thickness. We recommend that PT mats have a thickened edge at least 2 inches greater than the mat thickness and that the thickened edge be at least 12 inches wide.
ENGEO should be retained to review the PT mat foundation design.
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PT mats may be designed for an average allowable bearing pressure of up to 1,000 psf for dead-plus-live loads with maximum localized bearing pressures of 1,500 psf at column or wall loads. Allowable bearing pressures can be increased by one -third for wind or seismic loads.
Design PT mats using the criteria presented in Table 6.1-1 below.
TABLE 6.1-1: Post-Tensioned Mat Design Recommendations
CONDITION CENTER LIFT EDGE LIFT
Edge Moisture Variation Distance, em (feet) 9.0 5.0
Differential Soil Movement, ym (inches) 0.5 0.7
The above values are based on the procedure presented by the Post -Tensioning Institute “Standard Requirements for Design and Analysis of Shallow Post -Tensioned Concrete Foundations on Expansive and Stable Soils” (PTI DC10.5-19).
Underlay PT mats with a moisture reduction system as recommended below.
6.1.1 Slab Moisture Vapor Reduction
When buildings are constructed with concrete slab-on-grade, such as post-tensioned mats, water vapor from beneath the slab will migrate through the slab and into the building. This water vapor can be reduced but not stopped. Vapor transmission can negatively affect floor coverings and lead to increased moisture within a building. When water vapor migrating through the slab would be undesirable, we recommend the followi ng to reduce, but not stop, water vapor transmission upward through the slab-on-grade.
1. Install a vapor retarder membrane directly beneath the slab. Seal the vapor retarder at all seams and pipe penetrations. Vapor retarders shall conform to Class A vapor retarder in accordance with ASTM E1745, latest edition, “Standard Specification for Plastic Water Vapor Retarders used in Contact with Soil or Granular Fill under Concrete Slabs.”
2. Concrete shall have a concrete water-cement ratio of no more than 0.50.
3. Provide inspection and testing during concrete placement to check that the proper concrete and water-cement ratio are used.
4. Moist cure slabs for a minimum of 3 days or use other equivalent curing specific by the structural engineer.
The structural engineer should be consulted as to the use of a layer of clean sand or pea gravel (less than 5 percent passing the U.S. Standard No. 200 Sieve) placed on top of the vapor retarder membrane to assist in concrete curing.
7.0 FOUNDATION RECOMMENDATIONS – ANCILLARY
STRUCTURES
We developed structural improvement recommendations using data obtained from our field exploration, laboratory test results, and engineering analysis.
In general, ancillary structures can be supported on conventional footings or helical piles. The following recommendations should be incorporated into the foundation design.
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7.1 CONVENTIONAL FOOTINGS
7.1.1 Footing Dimensions and Allowable Bearing Capacity
Provide minimum footing dimensions as follows in Table 7.1.1-1 below.
TABLE 7.1.1-1: Minimum Footing Dimensions
FOOTING TYPE *MINIMUM DEPTH
(inches)
MINIMUM WIDTH
(inches)
Continuous 18 18
Isolated 18 24
* Below lowest adjacent pad grade
Minimum footing depths shown above are taken from lowest adjacent pad grade. Any cold joints between the exterior footing and slab-on-grade should be located at least 4 inches above adjacent exterior grade.
Design foundations recommended above for a maximum allowable bearing pressure of 1,500 psf for dead-plus-live loads. Increase this bearing capacity by one-third for the short-term effects of wind or seismic loading.
The maximum allowable bearing pressure is a net value; the weight of the footing may be neglected for design purposes. Footings located adjacent to utility trenches should have their bearing surfaces below an imaginary 1:1 (horizontal:vertical) plane projected upward from the bottom edge of the trench to the footing.
7.1.2 Foundation Lateral Resistance
Lateral loads may be resisted by friction along the base and by passive pressure along the sides of foundations. The passive pressure is based on an equivalent fluid pressure in pounds per cubic foot (pcf). We recommend the following allowable values for design.
• Passive Lateral Pressure: 300 pcf
• Coefficient of Friction: 0.35
The values above are unfactored and an appropriate factor of safety should be included, as necessary, based on the method of analysis and design combination. We recommend half of the passive resistance to be used if both passive pressure and friction are used in combination. The upper 1 foot of soil should be excluded from passive pressure computations unless it is confined by pavement or a concrete slab. Additionally, passive pressure should be ignored where lateral confinement is less than 10 feet to daylight. Based on the proposed wall layout and existing grades of the slope, passive resistance should be ignored at elevations above 389 feet (NAVD88).
Foundations may require deepening to meet these conditions.
7.2 HELICAL PILES
It is our understanding from you that the retaining walls may be supported utilizing helical piles.
However, vertical helical piles will not provide significant lateral load resistance so grade beams or battered piles may be necessary.
Helical piles should be designed according to the soil parameters listed below.
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Table 7.2-1: Helical Pier Design Soil Parameters
SOIL MATERIALS UNIT WEIGHT (pcf) FRICTION ANGLE
(degrees)
COHESION
(psf)
Foundation Soils 125 26 0
A minimum length should be determined to ensure helical piles achieve adequate lateral confinement with the adjacent slope to the west. Lateral and axial capacity of the piles should not be considered until 10 feet of lateral confinement from the adjacent slope is achieved. Based on the proposed wall layout and existing grades of the slope, pile capacity should be ignored at elevations above 389 feet (NAVD88).
To achieve lateral resistance within a helical pile system, we recommend that the helical piles are connected to a pile cap. The pile cap may provide a n unfactored passive resistance of 300 pcf (as discussed in Section 7.1.2). If additional lateral resistance is necessary, the helical piles may be battered. Lateral resistance from battered piles should be ignored within the active soil pressure zone of the retained soil, which can be considered as an imaginary line starting 5 feet inward from the base of the back of the wall and extending upward into the retained soil at an angle of (45 + φ/2).
7.2.1 Construction Considerations
A contractor experienced in the construction of helical piles should perform the construction. The successful performance of helical wall systems is dependent on proper installation methods. The geotechnical engineer should perform full-time monitoring of helical pile installation and testing.
Localized areas of dense soil should be anticipated during installation, which may make installation difficult or infeasible. Therefore, it may be necessary to predrill helical piles prior to installation. Helical piles must achieve the design embedment le ngth and torque requirements regardless of drilling conditions.
An appropriate testing program should be developed for our approval. The load-testing program should consider alternative soil conditions and methods, such as predrilling, employed during construction.
8.0 SLABS-ON-GRADE
8.1 EXTERIOR FLATWORK
Exterior flatwork includes items such as concrete sidewalks, steps, and outdoor courtyards exposed to foot traffic only. Provide a minimum section of 4 inches of concrete over 4 inches of aggregate base . Compact the aggregate base to at least 90 percent relative compaction (ASTM D1557). Thicken flatwork edges to at least 8 inches to help control moisture variations in the subgrade and place wire mesh or rebar within the middle third of the slab to help control the width and offset of cracks . Construct control and construction joints in accordance with current Portland Cement Association Guidelines.
8.2 TRENCH BACKFILL
Backfill and compact all trenches below building slabs-on-grade and to 5 feet laterally beyond any edge in accordance with Section 5.5.
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9.0 RETAINING WALLS
9.1 LATERAL SOIL PRESSURES
Design proposed retaining walls to resist lateral earth pressures from adjoining natural materials and/or backfill and from any surcharge loads. Provided that adequate drainage is included as recommended below, design walls restrained from movement at the top to resist an equivalent fluid pressure of 60 pcf. In addition, design restrained walls to resist an additional uniform pressure equivalent to one-half of any surcharge loads applied at the surface.
Design unrestrained retaining walls with adequate drainage to resist an equivalent fluid pressure of 40 pcf plus one-third of any surcharge loads.
The above lateral earth pressures assume level backfill conditions and sufficient drainage behind the walls to prevent any build-up of hydrostatic pressures from surface water infiltration and/or a rise in the groundwater level. If adequate drainage is not provided, we recommend that an additional equivalent fluid pressure of 40 pcf be added to the values recommended above for both restrained and unrestrained walls. Damp-proofing of the walls should be included in areas where wall moisture would be problematic.
Construct a drainage system, as recommended below, to reduce hydrostatic forces behind the retaining wall.
9.2 RETAINING WALL DRAINAGE
Construct either graded rock drains or geosynthetic drainage composites behind the retaining walls to reduce hydrostatic lateral forces. For rock drain construction, we recommend two t ypes of rock drain alternatives.
1. A minimum 12 -inch-thick layer of Class 2 Permeable Filter Mater ial (Caltrans Specification 68-2.02F) placed directly behind the wall, or
2. A minimum 12-inch-thick layer of washed, crushed rock with 100 percent passing the ¾-inch sieve and less than 5 percent passing the No. 4 sieve. Envelop rock in a minimum 6-ounce, non-woven geotextile filter fabric.
For both types of rock drains:
1. Place the rock drain directly behind the walls of the structure.
2. Extend rock drains from the wall base to within 12 inches of the top of the wall.
3. Place a minimum of 4-inch-diameter perforated pipe (glued joints and end caps) at the base of the wall, inside the rock drain and fabric, with perforations placed down.
4. Place pipe at a gradient at least 1 percent to direct water away from the wall by gravity to a drainage facility.
ENGEO should review and approve geosynthetic composite drainage systems prior to use.
9.3 BACKFILL
Backfill behind retaining walls should be placed and compacted in accordance with Section 5.5.
Use light compaction equipment within 5 feet of the wall face. If heavy compaction equipment is used, the walls should be temporarily braced to avoid excessive wall movement.
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9.4 FOUNDATIONS
Site walls may be supported on continuous footings designed in accordance with recommendations presented in Section 7.1, except the minimum embedment depth should be increased to 24 inches below lowest adjacent soil grade , or helical piers design in accordance with recommendations presented in Section 7.2. Walls along the western site boundary at the top of the slope may be supported on helical piers only.
10.0 PAVEMENT DESIGN
10.1 PRELIMINARY FLEXIBLE PAVEMENTS
Because of the variable near-surface soil, it is our opinion that a resistance value (R-value) of 5 is applicable for preliminary design. The R-value of the subgrade should be confirmed during site grading. Using estimated traffic indexes (TI) for various pavement loading requirements, we developed the following recommended pavement sections using Topic 633 of the Caltrans Highway Design Manual (including the asphalt factor of safety), presented in the table below.
TABLE 10.1-1: Recommended Hot Mix Asphalt Concrete Pavement Sections
TRAFFIC INDEX
SECTION
HOT MIX ASPHALT
(inches)
CLASS 2 AGGREGATE BASE
(inches)
5 3 10
6 3½ 13
7 4 16
8 5 18
The civil engineer should determine the appropriate traffic indexes based on the estimated traffic loads and frequencies. The minimum pavement section(s) should be confirmed by the civil engineer and local jurisdiction (such as City or County).
Pavement materials and construction should comply with the specifications and requirements of the Standard Specifications by Caltrans, the local jurisdiction, and our compaction recommendations in Section 9.3.
10.2 RIGID PAVEMENTS
Use concrete pavement sections to resist heavy loads and turning forces in areas such as fire lanes or trash enclosures. We recommend the following minimum design sections for rigid pavements.
• Use a minimum section of 6 inches of Portland Cement concrete over 4 inches of Caltrans Class 2 Aggregate Base
• Concrete pavement should have a minimum 28-day compressive strength of 3,500 psi • Provide minimum control joint spacing in accordance with Portland Cement Association Guidelines
Final design of rigid pavement sections and accompanying reinforcement should be performed based on estimated traffic loads and frequencies.
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10.3 SUBGRADE AND AGGREGATE BASE COMPACTION
Compact finish subgrade and aggregate base in accordance with Section 5.5. Aggregate base should meet the requirements for ¾-inch maximum Class 2 Aggregate Base in accordance with Section 26-1.02B of the latest Caltrans Standard Specifications.
10.4 CUTOFF CURBS
Saturated pavement subgrade or aggregate base can cause premature failure or increased maintenance of asphalt concrete pavements. This condition often occurs where landscape areas directly abut and drain toward pavements. If desired to install pavement cutoff barriers, they should be considered where pavement areas lie downslope of any landscape areas that are to be sprinklered or irrigated, and should extend to a depth of at least 4 inches below the base rock layer. Cutoff barriers may consist of deepened concrete curbs or deep-root moisture barriers.
If reduced pavement life and greater than normal pavement maintenance are acceptable to the owner, then the cutoff barrier may be eliminated.
11.0 LIMITATIONS AND UNIFORMITY OF CONDITIONS
This report presents geotechnical recommendations for design of the improvements discussed in Section 1.3 for the 10857 Linda Vista Drive Project . If changes occur in the nature or design of the project, we should be allowed to review this report and provide additional recommendations, if any. It is the responsibility of the owner to transmit the information and recommendations of this report to the appropriate organizations or people involved in design of the project, including but not limited to developers, owners, buyers, architects, engineers, and designers. The conclusions and recommendations contained in this report are solely professional opinions and are valid for a period of no more than 2 years from the date of report issuance.
We strive to perform our professional services in accordance with generally accepted principles and practices currently employed in the area; there is no warranty, express or implied. There are risks of earth movement and property damages inherent in building on or with earth materials.
We are unable to eliminate all risks; therefore, we are unable to guarantee or warrant the results of our services.
This report is based upon field and other conditions discovered at the time of report preparation.
We developed this report with limited subsurface exploration data. We assumed that ou r subsurface exploration data are representative of the actual subsurface conditions across the site. Considering possible underground variability of soil and groundwater, additional costs may be required to complete the project. We recommend that the owner establish a contingency fund to cover such costs. If unexpected conditions are encountered, ENGEO must be notified immediately to review these conditions and provide additional and/or modified recommendations, as necessary.
Our services did not include excavation sloping or shoring, soil volume change factors, flood potential, or a geohazard exploration. In addition, our geotechnical exploration did not include work to determine the existence of possible hazardous materials. If any hazardous materials are encountered during construction, the proper regulatory officials must be notified immediately.
SummerHill Homes 10857 Linda Vista Drive
25712.000.001 Design-Level Geotechnical Exploration
Page | 23 May 2, 2025
This document must not be subject to unauthorized reuse , that is, reusing without written authorization of ENGEO. Such authorization is essential because it requires ENGEO to evaluate the document’s applicability given new circumstances, not the least of which is passage of time.
Actual field or other conditions will necessitate clarifications, adjustments, modifications, or other changes to ENGEO’s documents. Therefore, ENGEO must be engaged to prepare the necessary clarifications, adjustments, modifications , or other changes before construction activities commence or further activity proceeds. If ENGEO’s scope of services does not include on -site construction observation, or if other persons or entities are retained to provide such services, ENGEO cannot be held responsible for an y or all claims arising from or resulting from the performance of such services by other persons or entities, and from any or all claims arising from or resulting from clarifications, adjustments, modifications, discrepancies , or other changes necessary to reflect changed field or other conditions.
We determined the lines designating the interface between layers on the exploration logs using visual observations. The transition between the materials may be abrupt or gradual. The exploration logs contain information concerning samples recovered, indications of the presence of various materials such as clay, sand, silt, rock, existing fill, etc., and observations of groundwater encountered. The field logs also contain our interpretation of the subsurface conditions between sample locations. Therefore, the logs contain both factual and interpretative information. Our recommendations are based on the contents of the final logs , which represent our interpretation of the field logs.
SummerHill Homes 10857 Linda Vista Drive
25712.000.001 Design-Level Geotechnical Exploration
May 2, 2025
SELECTED REFERENCES
American Society of Testing and Materials (ASTM). Annual Book of Standards.
American Concrete Institute (ACI). 2019. Building Code Requirements for Structural Concrete (ACI 318-19). ACI Committee 318 Structural Building Code.
American Society of Civil Engineers (ASCE). 2016. Minimum Design Loads for Buildings and Other Structures, ASCE Standard, ASCE/SEI 7-16.
Brabb, E. E., Graymer, R.W., and Jones, D.L., 2000, Geologic Map and Map Database of the Palo Alto 30’ x 60’ Quadrangle, California, U.S. Geological Survey
California Building Code. 2022.
California Department of Transportation (Caltrans). 2020. Highway Design Manual.
California Geological Survey (CGS). 2002. Seismic Hazard Zone Report for the Cupertino
7.5-Minute Quadrangle, Santa Clara County, California. Seismic Hazard Zone Report 068.
California Geological Survey (CGS). 2018. Earthquake Fault Zones – A Guide for Government Agencies, Property Owners / Developers, and Geoscience Practitioners for Assessing Fault Rupture Hazards in California: Special Publication 42 (SP42). Available at https://www.conservation.ca.gov/cgs/Documents/Publications/Special- Publications/SP_042.pdf.
CBG Engineers. 2025. Preliminary Grading Plan (C4.0) and Preliminary Grading Sections (C4.1). 10857 Linda Vista Drive, Cupertino, CA. February 3, 2025.
CLiq. 2023. Geologismiki Geotechnical Software. Version 3.5.2.22.
Dibblee, Thomas W. 2007 . Geologic map of the Cupertino San Jose West Quadrangle, Santa Clara County, California, 1:24,000.
ENGEO. 2024a. DRAFT Preliminary Geotechnical Exploration Report, 10857 Linda Vista Drive, Cupertino, California. July 3, 2024. Project No. 25712.000.001.
ENGEO. 2024b. Fault Exploration, 10857 Linda Vista Drive, Cupertino, California. September 20, 2024, Revised October 24, 2024. Project No. 25712.000.001.
Field, E.H., and 2014 Working Group on California Earthquake Probabilities. 2015. UCERF3: A new earthquake forecast for California’s complex fault system: U.S. Geological Survey 2015–3009, 6 p., https://dx.doi.org/10.3133/fs20153009.
Historical Aerials. Accessed in March 2025 from www.historicaerials.com.
Robertson, P.K. and Shao, L. 2010. Estimation of Seismic Compression in Dry Soils Using the CPT. International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics. 18.
SummerHill Homes 10857 Linda Vista Drive
25712.000.001 Design-Level Geotechnical Exploration
SELECTED REFERENCES (Continued)
May 2, 2025
Robertson, P. K. and Campanella, R. G. 1988. Guidelines for Geotechnical Design Using CPT and CPTU Data. Civil Engineering Department, University of British Columbia.
Robertson, P. K. 2009. Performance based earthquake design using the CPT, Gregg Drilling and Testing, Inc.
Santa Clara County (SCC). 2012. Geologic Hazard Zones.
Seed, R.B., et al. 2003 . Recent Advances in Soil Liquefaction Engineering: A Unified and Consistent Framework, Earthquake Engineering Research Center, Report No. EERC 2003-06, University of California, Berkeley.
Structural Engineers Association of California (SEAOC). 1999. Recommended Lateral Force Requirements and Commentary (Blue Book).
Tokimatsu, K., & Seed, H. B. 1987. Evaluation of settlements in sands due to earthquake shaking. Journal of geotechnical engineering, 113(8), 861-878.
United States Geological Survey (USGS). 2022. Interactive U.S. Fault Map. September 27. https://www.usgs.gov/tools/interactive-us-fault-map.
Willis et al. 2015. A next-generation Vs30 map for California based on geology and topography.
Bulletin of the Seismology Society of America.
Youd, T. L. and I. M. Idriss. 2001. Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshop on Evaluation of Liquefaction Resistance of Soil.
Zhang, G. Robertson. P.K, Brachman, R. 2002. Estimating Liquefaction Induced Ground Settlements from the CPT, Canadian Geotechnical Journal, 39: pp 1168-1180.
FIGURES
FIGURE 1: Vicinity Map
FIGURE 2: Site Plan
FIGURE 3: Regional Geologic Map
FIGURE 4: Regional Faulting and Seismicity Map
FIGURE 5: Seismic Hazards Zone Report
FIGURE 6: Santa Clara County Geologic Hazards Zone
FIGURE 7: City of Cupertino Geologic Hazards Zone
FIGURE NO.
CHECKED BY:DRAWN BY:
PROJECT NO. :
COPYRIGHT @ 2025 BY ENGEO INCORPORATED. THIS DOCUMENT MAY NOT BE REPRODUCED IN WHOLE OR IN PART BY ANY MEANS WHATSOEVER, NOR MAY IT BE QUOTED WITHOUT THE EXPRESS WRITTEN CONSENT OF ENGEO INCORPORATED.
ORIGINAL FIGURE PRINTED IN COLORPATH: G:\DRAFTING\PROJECTS\_24000 TO 25999\25712\25712000001\GEOTECH\GEX\10857 LINDA VISTA DRIVE.APRX LAYOUT: 01. VICINITY 8.5 X 11 PORTRAIT USER: NCLOUGH
AS SHOWNSCALE:
1 JTRNWC
25712.000.001
CUPERTINO, CALIFORNIA
10857 LINDA VISTA DRIVE
VICINITY MAP
SITE
SITE
NO SCALE
BASEMAP SOURCE: ENGEO INC, ESRI WORLD TOPO MAP
2,0001,0000
FEET
280
101
880
85 DRAFT
I
I
I
I
I
I
&
&
&
1-T1
1-T2
1-T3
1-CPT1
1-CPT3
1-CPT4
1-CPT2
2-B2
2-B1
2-B3
COPYRIGHT @ 2025 BY ENGEO INCORPORATED. THIS DOCUMENT MAY NOT BE REPRODUCED IN WHOLE OR IN PART BY ANY MEANS WHATSOEVER, NOR MAY IT BE QUOTED WITHOUT THE EXPRESS WRITTEN CONSENT OF ENGEO INCORPORATED.
ORIGINAL FIGURE PRINTED IN COLORPATH: G:\DRAFTING\PROJECTS\_24000 TO 25999\25712\25712000001\GEOTECH\GEX\10857 LINDA VISTA DRIVE.APRX LAYOUT: 02. SITE PLAN 8.5 X11 LANDSCAPE USER: NCLOUGH
AS SHOWNSCALE:
2 FIGURE NO.
JTRCHECKED BY:NWCDRAWN BY:
25712.000.001PROJECT NO. :
CUPERTINO, CALIFORNIA
10857 LINDA VISTA DRIVE
SITE PLAN
BASEMAP SOURCE: GOOGLE EARTH MAPPING SERVICE, 2025
100500
FEET
EXPLANATION────────────────────────────────────────ALL LOCATIONS ARE APPROXIMATE Project Site
25 Foot Residential Structural Setback From Top of Slope Slope Stability Cross Section
II Fault Trench (ENGEO, 2024)
& Boring (ENGEO, 2025)
Cone Penetration Test (ENGEO, 2024)
Linda Vista Drive
A A'
DRAFT
COPYRIGHT @ 2025 BY ENGEO INCORPORATED. THIS DOCUMENT MAY NOT BE REPRODUCED IN WHOLE OR IN PART BY ANY MEANS WHATSOEVER, NOR MAY IT BE QUOTED WITHOUT THE EXPRESS WRITTEN CONSENT OF ENGEO INCORPORATED.
ORIGINAL FIGURE PRINTED IN COLOR
PATH: G:\DRAFTING\PROJECTS\_24000 TO 25999\25712\25712000001\GEOTECH\LINDA VISTA FAULT EVALUATION\25712000001_LINDAVISTAFAULTEVALUATION.APRX LAYOUT: 03. GEOLOGIC 8.5 X 11 PORTRAIT USER: NCLOUGH
3 FIGURE NO.
GEOLOGIC MAP
SITE
BASEMAP SOURCE: BRABB,
GRAYMER, AND JONES, 2000
4,0002,0000
FEET
EXPLANATION
Contact - Depositional or intrusive
contact, dashed where approximately
located, dotted where concealed
Fault - Dashed where approximately
located, small dashes where inferred,
dotted where concealed, queried where
location is uncertain
Strike and dip of bedding
Qhaf
db
Qpaf
fl
Qhl
Tvq
Tblc
fs
Tmb
Artificial fill (Historic)af
Natural levee deposits (Holocene)Qhl
Landslide deposits
(Holocene and/or Pleistocene)
Qls
Alluvial fan and fluvial deposits (Holocene)Qhaf
Alluvial fan and fluvial deposits
(Pleistocene)
Qpaf
Santa Clara Formation
(lower Pleistocene and upper Pliocene)
QTsc
Monterey Formation (middle Miocene)Tm
Vaqueros Sandstone
(lower Miocene and Oligocene)
Tvq
Mindego Basalt and related volcanic rocks
(Miocene and/or Oligocene)
Tmb
ConglomerateTblc
Unnamed sedimentary rocks (Eocene?)Tu
Sandstonefs
Greenstonefg
Limestonefl
Chertfc
Sheared rock (Melange)fsr
Diabase and gabbro (Jurassic?)db
?
35 CHECKED BY:DRAWN BY:
PROJECT NO. :
AS SHOWNSCALE:
JTRNWC
25712.000.001
CUPERTINO, CALIFORNIA
10857 LINDA VISTA DRIVE
DRAFT
ALAMEDA
COUNTY
AMADOR COUNTY
CALAVERAS
COUNTY
CONTRA
COSTA
COUNTY
FRESNO COUNTY
MADERA
COUNTY
MARIN COUNTY
MARIPOSA
COUNTY
MERCED COUNTY
MONTEREY
COUNTY
NAPA
COUNTY
SACRAMENTO
COUNTY
SAN BENITO
COUNTY
SAN
FRANCISCO
COUNTY
SAN JOAQUIN
COUNTY
SAN MATEO
COUNTY
SANTA CLARA
COUNTY
SANTA CRUZ
COUNTY
SOLANO COUNTY
SONOMA COUNTY
STANISLAUS
COUNTY
TUOLUMNE
COUNTY
YOLO COUNTY
SITE
EXPLANATION
COPYRIGHT @ 2024 BY ENGEO INCORPORATED. THIS DOCUMENT MAY NOT BE REPRODUCED IN WHOLE OR IN PART BY ANY MEANS WHATSOEVER, NOR MAY IT BE QUOTED WITHOUT THE EXPRESS WRITTEN CONSENT OF ENGEO INCORPORATED.
PATH: G:\DRAFTING\PROJECTS\_24000 TO 25999\25712\25712000001\GEOTECH\GEX\10857 LINDA VISTA DRIVE.APRX LAYOUT: 04. FAULT&SEISMICITY 11 X 17 LANDSCAPE USER: MHAWKINS
ORIGINAL FIGURE PRINTED IN COLOR
4 FIGURE NO.
CHECKED BY:DRAWN BY:
AS SHOWNSCALE:
25712.000.001PROJECT NO. :
CUPERTINO, CALIFORNIA
10857 LINDA VISTA DRIVE
REGIONAL FAULTING AND SEISMICITY MAP
Project Site
HISTORIC EARTHQUAKE EPICENTERS
Magnitude 5-6
Magnitude 6-7
Magnitude 7+
Historic Blind Thrust Fault Zone
QUATERNARY FAULTS 2020
Based on time of most recent surface
deformation
Historical (<150 Years), Well
Constrained Location
Historical (<150 Years), Moderately
Constrained Location
Historical (<150 Years), Inferred
Location
Latest Quaternary (<15,000 Years),
Well Constrained Location
Latest Quaternary (<15,000 Years),
Moderately Constrained Location
Latest Quaternary (<15,000 Years),
Inferred Location
Latest Quaternary (<15,000 Years),
Inferred Location
Late Quaternary (<130,000 Years),
Moderately Constrained Location
Late Quaternary (<130,000 Years),
Inferred Location
Middle And Late Quaternary
(<750,000 Years), Well Constrained
Location
Middle And Late Quaternary
(<750,000 Years), Moderately
Constrained Location
Middle And Late Quaternary
(<750,000 Years), Inferred Location
Undifferentiated Quaternary(<1.6
Million Years), Well Constrained
Location
Undifferentiated Quaternary(<1.6
Million Years), Moderately
Constrained Location
Undifferentiated Quaternary(<1.6
Million Years), Inferred Location
Class B (Various Age), Well
Constrained Location
Class B (Various Age), Moderately
Constrained Location
Class B (Various Age), Inferred
Location
157.50
MILES
BASE MAP SOURCE:
CITY OF CUPERTINO, COUNTY OF SANTA CLARA, CALIFORNIA STATE PARKS, ESRI, TOMTOM, GARMIN, SAFEGRAPH, GEOTECHNOLOGIES, INC, METI/NASA, USGS, BUREAU OF LAND MANAGEMENT, EPA, NPS,
USDA, USFWS, CSUMB, ESRI, GARMIN, NATURALVUE, ESRI, GEBCO, GARMIN, NATURALVUE, COUNTY OF SANTA CLARA, CALIFORNIA STATE PARKS, ESRI, TOMTOM, GARMIN, SAFEGRAPH, FAO, METI/NASA,
USGS, BUREAU OF LAND MANAGEMENT, EPA, NPS, USFWS
COLOR HILLSHADE IMAGE BASED ON THE NATIONAL ELEVATION DATA SET (NED) AT 30 METER RESOLUTION U.S.G.S. QUATERNARY FAULT DATABASE, 2020
C.G.S. HISTORIC EARTHQUAKE DATABASE
JTRNWC
DRAFT
SITE
COPYRIGHT @ 2025 BY ENGEO INCORPORATED. THIS DOCUMENT MAY NOT BE REPRODUCED IN WHOLE OR IN PART BY ANY MEANS WHATSOEVER, NOR MAY IT BE QUOTED WITHOUT THE EXPRESS WRITTEN CONSENT OF ENGEO INCORPORATED.
ORIGINAL FIGURE PRINTED IN COLORPATH: G:\DRAFTING\PROJECTS\_24000 TO 25999\25712\25712000001\GEOTECH\GEX\10857 LINDA VISTA DRIVE.APRX LAYOUT: 05. SEISMIC HAZARD ZONE MAP 8.5 X 11 PORTRAIT USER: NCLOUGH 5 FIGURE NO.
SEISMIC HAZARD ZONES MAP
BASEMAP SOURCE: ESRI MAPPING SERVICE CALIFORNIA DEPARTMENT OF CONSERVATION, CALIFORNIA GEOLOGICAL SURVEY, CUPERTINO QUADRANGLE, 2002 Earthquake-Induced Landslide Zones
Areas Where The Previous Occurrence Of Landslide
Movement, Or Local Topographic, Geological, Geotechnical And Subsurface Water Conditions Indicate A Potential For Permanent Ground Displacements Such That Mitigation As
Defined In Public Resources Code Section 2693(C) Would
Be Required.
Liquefaction Zones
Areas Where The Historical Occurrence Of Liquefaction, Or Local Geological, Geotechnical And Groundwater Conditions Indicate A Potential For Permanent Ground Displacements Such That Mitigation As Defined In Public Resources Code Section 2693(C) Would Be Required
EXPLANATION
─────────────────────────────────────
2,0001,0000
FEET
CHECKED BY:DRAWN BY:
PROJECT NO. :
AS SHOWNSCALE:
JTRNWC
25712.000.001
CUPERTINO, CALIFORNIA
10857 LINDA VISTA DRIVE
DRAFT
SITE
EXPLANATION────────────────────────────────────────
Project Site
County Fault Rupture Hazard Zones
County Landslide Hazard Zones
County Liquefaction Hazard Zones
6 JTRCHECKED BY:NWCDRAWN BY:
25712.000.001PROJECT NO. :
CUPERTINO, CALIFORNIA
10857 LINDA VISTA DRIVE
SANTA CLARA COUNTY GEOLOGIC HAZARD ZONES
BASEMAP SOURCE: ESRI WORLD TOPO MAP; AND SANTA CLARA BOARD OF SUPERVISORS, 2002 2,0001,0000
FEET
AS SHOWNSCALE:
PATH: G:\DRAFTING\PROJECTS\_24000 TO 25999\25712\25712000001\GEOTECH\LINDA VISTA FAULT EVALUATION\25712000001_LINDAVISTAFAULTEVALUATION.APRX LAYOUT: 05. SANTA CLARA COUNTY GEOLOGIC HAZARD ZONES 8.5 X 11 PORTRAIT USER: NCLOUGHCOPYRIGHT @ 2025 BY ENGEO INCORPORATED. THIS DOCUMENT MAY NOT BE REPRODUCED IN WHOLE OR IN PART BY ANY MEANS WHATSOEVER, NOR MAY IT BE QUOTED WITHOUT THE EXPRESS WRITTEN CONSENT OF ENGEO INCORPORATED.
ORIGINAL FIGURE PRINTED IN COLOR
FIGURE NO.
DRAFT
7 JTRCHECKED BY:NWCDRAWN BY:
25712.000.001PROJECT NO. :
CUPERTINO, CALIFORNIA
10857 LINDA VISTA DRIVE
CITY OF CUPERTINO GEOLOGIC AND SEISMIC HAZARDS MAP
BASEMAP SOURCE: GOOGLE EARTH MAPPING
SERVICE 2025; AND, COTTON SHIRES & ASSOCIATES, INC., 2003 1,0005000
FEET
EXPLANATION────────────────────────────────────────
Project Site
F Fault Rupture (Cotton, Shires & Associates, 2003)
H Hillside (Cotton, Shires & Associates, 2003)
L Liquefaction/Inundation (Cotton, Shires & Associates, 2003) S Slope Instability (Cotton, Shires & Associates, 2003) V Valley Floor (Cotton, Shires & Associates, 2003)
Fault Trace (Hitchcock, 1994)
AS SHOWNSCALE:
PATH: G:\DRAFTING\PROJECTS\_24000 TO 25999\25712\25712000001\GEOTECH\GEX\10857 LINDA VISTA DRIVE.APRX LAYOUT: 07. CITY OF CUPERTINO GEOLOGIC AND SEISMIC HAZARDS MAP 8.5 X 11 PORTRAIT USER: NCLOUGHCOPYRIGHT @ 2025 BY ENGEO INCORPORATED. THIS DOCUMENT MAY NOT BE REPRODUCED IN WHOLE OR IN PART BY ANY MEANS WHATSOEVER, NOR MAY IT BE QUOTED WITHOUT THE EXPRESS WRITTEN CONSENT OF ENGEO INCORPORATED.
ORIGINAL FIGURE PRINTED IN COLOR
FIGURE NO.
Known Fault (Cotton, Shires & Associates, 2003)
Inferred Fault (Cotton, Shires & Associates, 2003)
Concealed Fault (Cotton, Shires & Associates, 2003)
DRAFT
APPENDIX A
KEY TO BORING LOGS
BORING LOGS
SILTS AND CLAYS LIQUID LIMIT GREATER THAN 50%SILTS AND CLAYS LIQUID LIMITS 50% OR LESS
DESCRIPTION
HIGHLY ORGANIC SOILSSILTS AND CLAYS20040104
MAJOR TYPESGW - Well graded gravels or gravel-sand mixturesSC - Clayey sand, sand-clay mixturesOL - Low plasticity organic silts and claysMH - Inorganic silt with high plasticityCH - Inorganic clay with high plasticityOH - Highly plastic organic silts and claysFINERELATIVE DENSITYBLOWS/FOOTGRAIN SIZES
KEY TO BORING LOGS
COARSEMEDIUM3"12"BOULDERSCOBBLESCOARSEFINEPT - Peat and other highly organic soilsML - Inorganic silt with low to medium plasticitySANDGRAVELLINE TYPES_ _ _ _ _ _GROUND-WATER SYMBOLSMOISTURE CONDITION GP - Poorly graded gravels or gravel-sand mixtures
SANDS AND GRAVELS
GM - Silty gravels, gravel-sand and silt mixturesGC - Clayey gravels, gravel-sand and clay mixturesSW - Well graded sands, or gravelly sand mixturesSP - Poorly graded sands or gravelly sand mixturesCL - Inorganic clay with low to medium plasticitySILTSANDCLAYSSAMPLER SYMBOLSCONSISTENCYU.S. STANDARD SERIES SIEVE SIZECLEAR SQUARE SIEVE OPENINGSSM - Silty sand, sand-silt mixtures3/4 " GRAVELSMORE THAN HALFCOARSE FRACTIONIS LARGER THANNO. 4 SIEVE SIZESANDSMORE THAN HALFCOARSE FRACTIONIS SMALLER THANNO. 4 SIEVE SIZECLEAN GRAVELS WITHLITTLE OR NO FINESGRAVELS WITH OVER12 % FINESCLEAN SANDS WITHLITTLE OR NO FINESSANDS WITH OVER12 % FINESCOARSE-GRAINED SOILS MORE THANHALF OF MAT'L LARGER THAN #200 SIEVETHAN #200 SIEVEFINE-GRAINED SOILS MORETHAN HALF OF MAT'L SMALLERVERY LOOSELOOSEMEDIUM DENSEDENSEVERY DENSE0-44-1010-3030-50OVER 50VERY SOFTSOFTMEDIUM STIFFSTIFFVERY STIFFHARD0-250250-500500-1,0001,000-2,0002,000-4,000> 4,000DRYMOISTWETAbsence of moisture, dusty, dry to touchDamp but no visible waterVisible freewaterSolid - Layer BreakDashed - Gradational or approximate layer breakGroundwater level during drillingStabilized groundwater levelModified California (3-inch O.D.) SamplerCalifornia (2.5-inch O.D.) SamplerS.P.T. Split Spoon (2-inch O.D.) SamplerShelby TubeContinuous CoreBag SamplesGrab SamplesNo Recovery Expect Excellence NOTES1.Standard Penetration Tests (S.P.T.) number of blows for a 140-poundhammer falling 30 inches to drive a 2-inch O.D. (1-3/8-inch I.D.) sampler,assuming 60% hammer efficiency2.Approximate shear strength measured in field at time of drilling in units ofpounds per square foot (S.P.T.)1 APPROXIMATE SHEARSTRENGTH (PSF)2
APPENDIX B
LABORATORY TEST DATA
= = =
= = =
= = =
2633 Camino Ramon, Suite 150 | San Ramon, CA 94583 | T: (925) 355-9047 | F: (925) 355-9052 | www.engeo.com REPORT DATE: 4/25/2025
TESTED BY: Y. Cabrales
REVIEWED BY: G. Criste
CLIENT: SummerHill Homes
PROJECT NAME: 10857 Linda Vista Drive
PROJECT NO: 25712.000.001 PH003
PROJECT LOCATION:
* (no specification provided)
Cupertino, CA
REMARKS
CLASSIFICATION
USCS =
D10 Cu Cc
Soak time = 180 min
Dry sample weight = 725.82 g
LL = PI =
COEFFICIENTS
D90 D85 D60
D50 D30 D15
ASTM D1140, Method B
PARTICLE SIZE DISTRIBUTION REPORT
SIEVE
SIZE
PERCENT
FINER
SPEC.*
PERCENT
PASS?
(X=NO)
SOIL DESCRIPTION
See exploration logs
#200 14
ATTERBERG LIMITS
PL =
SAMPLE ID:
10 2-B1@10'
% FINES
SILT CLAY
% +75mm
% GRAVEL % SAND
COARSE FINE COARSE
DEPTH (ft):
MEDIUM FINE
14 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.0010.010.1110100
PERCENT FINER
GRAIN SIZE - mm.
6 in.
3 in.
2 in.
1 ½
in.1 in.
¾ in.
½ in.
⅜ in.
#4
#10
#20
#40
#60
#100
#140
#200
= = =
= = =
= = =
2633 Camino Ramon, Suite 150 | San Ramon, CA 94583 | T: (925) 355-9047 | F: (925) 355-9052 | www.engeo.com REPORT DATE: 4/25/2025
TESTED BY: Y. Cabrales
REVIEWED BY: G. Criste
CLIENT: SummerHill Homes
PROJECT NAME: 10857 Linda Vista Drive
PROJECT NO: 25712.000.001 PH003
PROJECT LOCATION:
* (no specification provided)
Cupertino, CA
REMARKS
CLASSIFICATION
USCS =
D10 Cu Cc
LL = PI =
0.0750 mm
COEFFICIENTS
D90 15.5543 mm D85 12.7000 mm D60 4.5000 mm
D50 2.6207 mm D30 0.5224 mm D15
ASTM D6913, Method A
PARTICLE SIZE DISTRIBUTION REPORT
SIEVE
SIZE
PERCENT
FINER
SPEC.*
PERCENT
PASS?
(X=NO)
SOIL DESCRIPTION
See exploration logs
1 in.
¾ in.
½ in.
⅜ in.
#4
#10
#20
#40
#60
#100
#140
#200
100
95 85
79 61
45 35
28 23
19 17
15 ATTERBERG LIMITS
PL =
SAMPLE ID:
26 2-B1@26'
34 16 17 13
% FINES
SILT CLAY
% +75mm
% GRAVEL % SAND
COARSE FINE COARSE
5 DEPTH (ft):
MEDIUM FINE
15 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.0010.010.1110100
PERCENT FINER
GRAIN SIZE - mm.
6 in.
3 in.
2 in.
1 ½
in.1 in.
¾ in.
½ in.
⅜ in.
#4
#10
#20
#40
#60
#100
#140
#200
= = =
= = =
= = =
2633 Camino Ramon, Suite 150 | San Ramon, CA 94583 | T: (925) 355-9047 | F: (925) 355-9052 | www.engeo.com REPORT DATE: 4/25/2025
TESTED BY: Y. Cabrales
REVIEWED BY: G. Criste
CLIENT: SummerHill Homes
PROJECT NAME: 10857 Linda Vista Drive
PROJECT NO: 25712.000.001 PH003
PROJECT LOCATION:
* (no specification provided)
Cupertino, CA
REMARKS
CLASSIFICATION
USCS = CL
D10 Cu Cc
Silt/clay division of 0.002mm used
PI: ASTM D4318, Wet Method
USCS: ASTM D2487
LL = 25 PI = 11
COEFFICIENTS
D90 3.5158 mm D85 1.3038 mm D60 0.0864 mm
D50 0.0486 mm D30 0.0120 mm D15
ASTM D422
PARTICLE SIZE DISTRIBUTION REPORT
SIEVE
SIZE
PERCENT
FINER
SPEC.*
PERCENT
PASS?
(X=NO)
SOIL DESCRIPTION
See exploration logs
1 in.
¾ in.
½ in.
⅜ in.
#4
#10
#20
#40
#60
#100
#140
#200
0.0310 mm.
0.0201 mm.
0.0119 mm.
0.0085 mm.
0.0060 mm.
0.0030 mm.
0.0013 mm.
100.0
98.2 97.3
95.1 91.6
87.0 83.0
79.6 75.4
68.8 63.3
57.6 42.1
35.2 29.9
28.2 25.6
21.2 17.5
ATTERBERG LIMITS
PL = 14
SAMPLE ID:
2 2-B2@2
6.6 4.6 7.4 22.0
% FINES
SILT CLAY
% +75mm
% GRAVEL % SAND
COARSE FINE COARSE
1.8 DEPTH (ft):
MEDIUM FINE
38.1 19.5
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.0010.010.1110100
PERCENT FINER
GRAIN SIZE - mm.
6 in.
3 in.
2 in.
1 ½
in.1 in.
¾ in.
½ in.
⅜ in.
#4
#10
#20
#40
#60
#100
#140
#200
= = =
= = =
= = =
2633 Camino Ramon, Suite 150 | San Ramon, CA 94583 | T: (925) 355-9047 | F: (925) 355-9052 | www.engeo.com REPORT DATE: 4/25/2025
TESTED BY: Y. Cabrales
REVIEWED BY: G. Criste
CLIENT: SummerHill Homes
PROJECT NAME: 10857 Linda Vista Drive
PROJECT NO: 25712.000.001 PH003
PROJECT LOCATION:
* (no specification provided)
Cupertino, CA
REMARKS
CLASSIFICATION
USCS =
D10 Cu Cc
Soak time = 180 min
Dry sample weight = 98.61 g
LL = PI =
COEFFICIENTS
D90 D85 D60
D50 D30 D15
ASTM D1140, Method B
PARTICLE SIZE DISTRIBUTION REPORT
SIEVE
SIZE
PERCENT
FINER
SPEC.*
PERCENT
PASS?
(X=NO)
SOIL DESCRIPTION
See exploration logs
#200 27.5
ATTERBERG LIMITS
PL =
SAMPLE ID:
15.5-16
[email protected]'
% FINES
SILT CLAY
% +75mm
% GRAVEL % SAND
COARSE FINE COARSE
DEPTH (ft):
MEDIUM FINE
27.5 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.0010.010.1110100
PERCENT FINER
GRAIN SIZE - mm.
6 in.
3 in.
2 in.
1 ½
in.1 in.
¾ in.
½ in.
⅜ in.
#4
#10
#20
#40
#60
#100
#140
#200
= = =
= = =
= = =
DEPTH (ft):
MEDIUM FINE
33.9 17.9
SAMPLE ID:
1.5-2
[email protected]'
9.3 9.0 11.5 18.4
% FINES
SILT CLAY
% +75mm
% GRAVEL % SAND
COARSE FINE COARSE
ASTM D422
PARTICLE SIZE DISTRIBUTION REPORT
SIEVE
SIZE
PERCENT
FINER
SPEC.*
PERCENT
PASS?
(X=NO)
SOIL DESCRIPTION
See exploration logs
¾ in.
½ in.
⅜ in.
#4
#10
#20
#40
#60
#100
#140
#200
0.0319 mm.
0.0207 mm.
0.0121 mm.
0.0087 mm.
0.0061 mm.
0.0031 mm.
0.0013 mm.
100.0
98.2 96.5
90.7 81.7
74.7 70.2
65.9 60.6
56.9 51.8
37.4 31.5
27.3 24.8
24.0 19.7
16.1 ATTERBERG LIMITS
PL = 13 LL = 23 PI = 10
COEFFICIENTS
D90 4.4409 mm D85 2.7465 mm D60 0.1416 mm
D50 0.0674 mm D30 0.0171 mm D15
* (no specification provided)
Cupertino, CA
REMARKS
CLASSIFICATION
USCS = CL
D10 Cu Cc
Silt/clay division of 0.002mm used
PI: ASTM D4318, Wet Method
USCS: ASTM D2487
2633 Camino Ramon, Suite 150 | San Ramon, CA 94583 | T: (925) 355-9047 | F: (925) 355-9052 | www.engeo.com REPORT DATE: 4/25/2025
TESTED BY: Y. Cabrales
REVIEWED BY: G. Criste
CLIENT: SummerHill Homes
PROJECT NAME: 10857 Linda Vista Drive
PROJECT NO: 25712.000.001 PH003
PROJECT LOCATION:
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.0010.010.1110100
PERCENT FINER
GRAIN SIZE - mm.
6 in.
3 in.
2 in.
1 ½
in.1 in.
¾ in.
½ in.
⅜ in.
#4
#10
#20
#40
#60
#100
#140
#200
B
MOISTURE-DENSITY DETERMINATION REPORT
ASTM D7263
SAMPLE ID
2-B3
@30'
DEPTH (ft.) 30
MOISTURE CONTENT (%) 19.5
METHOD A OR B
DRY DENSITY (pcf) 109.9
REPORT DATE: 4/25/2025
TESTED BY: Y. Cabrales
CLIENT: SummerHill Homes
PROJECT NAME: 10857 Linda Vista Drive
REVIEWED BY: G. Criste
PROJECT NO: 25712.000.001 PH003
PROJECT LOCATION: Cupertino, CA
2633 Camino Ramon, Suite 150 | San Ramon, CA 94583 | T: (925) 355-9047 | F: (888) 279-2698 | www.engeo.com
LIQUID AND PLASTIC LIMITS TEST REPORT
ASTM D4318
2-B2@2'
SAMPLE ID TEST METHOD REMARKS
2633 Camino Ramon, Suite 150 | San Ramon, CA 94583 | T: (925) 355-9047 | F: (925) 355-9052 | www.engeo.com PROJECT LOCATION:
PROJECT NO:
PROJECT NAME:
CLIENT:
REPORT DATE:
Y. Cabrales
G. Criste
TESTED BY:
REVIEWED BY:
10857 Linda Vista Drive
2-B2@2' See exploration logs 25 142
[email protected]' See exploration logs 23 131.5-2
SAMPLE ID MATERIAL DESCRIPTION LL PL PIDEPTH (ft)
11 10
SummerHill Homes
25712.000.001 PH003
Cupertino, CA
4/25/2025
PI: ASTM D4318, Wet Method
PI: ASTM D4318, Wet Method
0 10
20 30
40 50
60 70
80 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
PLASTICITY INDEX
LIQUID LIMIT
MH or OH
CH or OH
CL-ML
ML or OL
CL or OL
Dashed Line indicates the approximate
upper limit boundary for natural soils
APPENDIX C
PREVIOUS EXPLORATIONS (ENGEO)
Cone Penetration Test Report
Trench Logs
35(6(17$7,212)6,7(
,19(67,*$7,215(68/76
Prepared for:
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ENGEO, Inc.
24-56-27871
2024-06-20
2024-06-20
2024-06-25
ConeTec, Inc.
506 De Carlo Ave, Richmond, CA 94801
Tel: (510) 357-3677
[email protected]
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ENGEO, Inc.
10857 Linda Vista Drive
24-56-27871
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Client:
Project:
Date:
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10857 Linda Vista Drive
2024-06-25
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3rd Party Disclaimer
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10857 Linda Vista Drive
ENGEO, Inc.
ENGEO, Inc.
10857 Linda Vista Drive
Alan Sweeney
Anthony Rasmussen
PROJECT INFORMATION
Rig
Description Deployment System Test Type
C02-015 CPT Truck Rig Twin mo unted cylinders CPTu/SCPTu
Coordinates
Test Type Collection Method EPSG Number
CPTu/SCPTu Consumer Grade GPS 32610 (WGS84 / UTM Zone 10 North)
Piezocones Used for this Project
Cone Description Cone
Number
Cross
Sectional Area
(cm2)
Sleeve
Area
(cm2)
Tip
Capacity
(bar)
Sleeve
Capacity
(bar)
Pore Pressure
Capacity
(bar)
EC1061:T1500F15U35 1061 15 225 1500 15 35
The CPTu summary indicates which cone was used for each sounding.
Cone Penetration Test (CPTu)
Depth reference Depths are referenced to the existing ground surface at the time of each test.
Tip and sleeve data offset 0.1 Meters. This has been accounted for in the CPT data files.
Additional Comments None
Calculated Geotechnical Parameters
Additional information
The Normalized Soil Behaviour Type Chart based on Qtn (SBT Qtn) (Robertson, 2009) was used to classify the soil for this project. A detailed set of calculated CPTu parameters have been generated and are provided in Excel format files in the release folder. The CPTu parameter calculations are based on values of corrected tip resistance (qt) sleeve friction (fs) and pore pressure (u2).
Effective stresses are calculated based on unit weights that have been assigned to the individual soil behaviour type zones and the assumed equilibrium pore pressure profile.
Soils were classified as either drained or undrained based on the Qtn Normalized Soil Behaviour Type Chart (Robertson, 2009). Calculations for both drained and undrained parameters were included for materi als that classified as silt mixtures (zone 4).
REPORT APPENDICES
The appendices listed below are included in the report:
Cone Penetration Test (CPTu) Summary and Standard CPTu Plots Advanced Cone Penetration Test Plots with Ic, Su(Nkt), Phi, and N1(60)Ic Soil Behavior Type (SBT) Scatter Plots
Pore Pressure Dissipation Test (PPDT) Summary and PPDT Plots Seismic Cone Penetration Test (SCPTu) Tabular Results SCPTu Test Plots
SCPTu Velocity Wave Traces
Supplementary Documents and Materials
Cone Penetration Test (CPTu) Summary and Standard
CPTu Plots
Job No: 24-56-27871
Client: ENGEO, Inc.
Project: 10857 Linda Vista Drive
Start Date: 20-Jun-2024
End Date: 20-Jun-2024
CONE PENETRATION TEST SUMMARY
Sounding ID File Name Date Cone Cone Area
(cm2)
Assumed Phreatic
Surface1
(ft)
Final
Depth
(ft)
Seismic
Intervals
Northing2
(m)
Easting2
(m)
Surface
Elevation³
(ft)
Refer to
Notation
Number
1-CPT1 24-56-27871_SP01 2024-06-20 1061:T1500F15U35 15 >58 58.40 18 4129708 583221 397 1-CPT2 24-56-27871_CP02 2024-06-20 1061:T1500F15U35 15 >9 9.27 4129728 583270 394 1-CPT2B 24-56-27871_CP02B 2024-06-20 1061:T1500F15U35 15 >36 36.50 4129727 583269 394 1-CPT3 24-56-27871_CP03 2024-06-20 1061:T1500F15U35 15 >41 41.34 4129668 583245 397 1-CPT4 24-56-27871_CP04 2024-06-20 1061:T1500F15U35 15 >44 44.46 4129677 583314 394 Totals 5 Soundings 189.96 ft
1. The phreatic surface is assumed to be beyond the depth of the sounding for the calculated parameters.
2. The coordinates were collected using a consumer grade GPS receiver. EPSG number: 32610 (WGS84 / UTM Zone 10 North).
3. Elevations taken from Google Earth.
Sheet 1 of 1
The reported coordinates were acquired from consumer grade GPS equipment and are only approximate locations. The coordinates should not be used for design purposes. 0 50010000
5 10
15 20
25 30
35 40
45 50
55 60
qt (tsf)
Depth (feet)
0.05.010.0fs (tsf)
0.02.55.07.5Rf (%)
0 501000u (ft)
0369SBT Qtn
ENGEOJob No: 24-56-27871Date: 2024-06-20 08:13Site: 10857 Linda Vista DriveSounding: 1-CPT1Cone: 1061:T1500F15U35 Max Depth: 17.800 m / 58.40 ftDepth Inc: 0.025 m / 0.082 ftAvg Int: Every PointFile: 24-56-27871_SP01.CORUnit Wt: SBTQtn (PKR2009)SBT: Robertson, 2009 and 2010Coords: (UTM Zone 10 North) N: 4129708m E: 583221m Organic Soils
Sands
Sand Mixtures
Silt Mixtures
Stiff Sand to Clayey Sand
Sands
Stiff Sand to Clayey Sand
Sand Mixtures
Sand Mixtures
Sands
Gravelly Sand to Sand
Sands
Gravelly Sand to Sand
Sands
Gravelly Sand to Sand
Gravelly Sand to Sand
Sands
Sand Mixtures
Silt Mixtures
Silt Mixtures
Sands
Sand Mixtures
Sands
Sand Mixtures
Clays
Sand Mixtures
Sand Mixtures
Sand Mixtures
Sand Mixtures
Clays
Silt Mixtures
Sands
Gravelly Sand to Sand
Sands
Gravelly Sand to Sand
Undefined
Ueq(ft)
Refusal
Refusal
Refusal
Refusal
Overplot Item:
Assumed Ueq
Ueq
Dissipation, Ueq not achieved
Dissipation, Ueq achieved
Dissipation, Ueq assumed
Hydrostatic Line
The reported coordinates were acquired from consumer grade GPS equipment and are only approximate locations. The coordinates should not be used for design purposes. 0 50010000
5 10
15 20
25 30
35 40
45 50
55 60
qt (tsf)
Depth (feet)
0.05.010.0fs (tsf)
0.02.55.07.5Rf (%)
0 501000u (ft)
0369SBT Qtn
ENGEOJob No: 24-56-27871Date: 2024-06-20 11:05Site: 10857 Linda Vista DriveSounding: 1-CPT2Cone: 1061:T1500F15U35 Max Depth: 2.825 m / 9.27 ftDepth Inc: 0.025 m / 0.082 ftAvg Int: Every PointFile: 24-56-27871_CP02.CORUnit Wt: SBTQtn (PKR2009)SBT: Robertson, 2009 and 2010Coords: (UTM Zone 10 North) N: 4129728m E: 583270m Organic Soils
Sands
Sand Mixtures
Sands
Sands
Sand Mixtures
Ueq(ft)
Refusal
Refusal
Refusal
Refusal
Overplot Item:
Assumed Ueq
Ueq
Dissipation, Ueq not achieved
Dissipation, Ueq achieved
Dissipation, Ueq assumed
Hydrostatic Line
The reported coordinates were acquired from consumer grade GPS equipment and are only approximate locations. The coordinates should not be used for design purposes. 0 50010000
5 10
15 20
25 30
35 40
45 50
55 60
qt (tsf)
Depth (feet)
0.05.010.0fs (tsf)
0.02.55.07.5Rf (%)
0 501000u (ft)
0369SBT Qtn
ENGEOJob No: 24-56-27871Date: 2024-06-20 11:24Site: 10857 Linda Vista DriveSounding: 1-CPT2BCone: 1061:T1500F15U35 Max Depth: 11.125 m / 36.50 ftDepth Inc: 0.025 m / 0.082 ftAvg Int: Every PointFile: 24-56-27871_CP02B.CORUnit Wt: SBTQtn (PKR2009)SBT: Robertson, 2009 and 2010Coords: (UTM Zone 10 North) N: 4129727m E: 583269m Undefined
Sands
Sand Mixtures
Sands
Stiff Sand to Clayey Sand
Sands
Sand Mixtures
Gravelly Sand to Sand
Sands
Gravelly Sand to Sand
Sands
Gravelly Sand to Sand
Sands
Stiff Sand to Clayey Sand
Sands
Sands
Gravelly Sand to Sand
Sands
Gravelly Sand to Sand
Sands
Undefined
Ueq(ft)
Refusal
Refusal
Refusal
Refusal
Overplot Item:
Assumed Ueq
Ueq
Dissipation, Ueq not achieved
Dissipation, Ueq achieved
Dissipation, Ueq assumed
Hydrostatic Line
The reported coordinates were acquired from consumer grade GPS equipment and are only approximate locations. The coordinates should not be used for design purposes. 0 50010000
5 10
15 20
25 30
35 40
45 50
55 60
qt (tsf)
Depth (feet)
0.05.010.0fs (tsf)
0.02.55.07.5Rf (%)
0 501000u (ft)
0369SBT Qtn
ENGEOJob No: 24-56-27871Date: 2024-06-20 13:10Site: 10857 Linda Vista DriveSounding: 1-CPT3Cone: 1061:T1500F15U35 Max Depth: 12.600 m / 41.34 ftDepth Inc: 0.025 m / 0.082 ftAvg Int: Every PointFile: 24-56-27871_CP03.CORUnit Wt: SBTQtn (PKR2009)SBT: Robertson, 2009 and 2010Coords: (UTM Zone 10 North) N: 4129668m E: 583245m Sand Mixtures
Sands
Sand Mixtures
Sands
Sands
Stiff Sand to Clayey Sand
Sands
Sands
Stiff Sand to Clayey Sand
Sands
Silt Mixtures
Sands
Sand Mixtures
Sand Mixtures
Sands
Stiff Sand to Clayey Sand
Sand Mixtures
Silt Mixtures
Sand Mixtures
Sand Mixtures
Sands
Stiff Sand to Clayey Sand
Ueq(ft)
Refusal
Refusal
Refusal
Refusal
Overplot Item:
Assumed Ueq
Ueq
Dissipation, Ueq not achieved
Dissipation, Ueq achieved
Dissipation, Ueq assumed
Hydrostatic Line
The reported coordinates were acquired from consumer grade GPS equipment and are only approximate locations. The coordinates should not be used for design purposes. 0 50010000
5 10
15 20
25 30
35 40
45 50
55 60
qt (tsf)
Depth (feet)
0.05.010.0fs (tsf)
0.02.55.07.5Rf (%)
0 501000u (ft)
0369SBT Qtn
ENGEOJob No: 24-56-27871Date: 2024-06-20 12:23Site: 10857 Linda Vista DriveSounding: 1-CPT4Cone: 1061:T1500F15U35 Max Depth: 13.550 m / 44.45 ftDepth Inc: 0.025 m / 0.082 ftAvg Int: Every PointFile: 24-56-27871_CP04.CORUnit Wt: SBTQtn (PKR2009)SBT: Robertson, 2009 and 2010Coords: (UTM Zone 10 North) N: 4129677m E: 583314m Undefined
Sands
Sand Mixtures
Stiff Sand to Clayey Sand
Stiff Sand to Clayey Sand
Sands
Sands
Sands
Sands
Sand Mixtures
Silt Mixtures
Sand Mixtures
Stiff Sand to Clayey Sand
Silt Mixtures
Clays
Stiff Sand to Clayey Sand
Silt Mixtures
Sand Mixtures
Silt Mixtures
Silt Mixtures
Clays
Silt Mixtures
Clays
Sands
Sand Mixtures
Silt Mixtures
Sands
Silt Mixtures
Sands
Undefined
Ueq(ft)
Target Depth
Target Depth
Target Depth
Target Depth
Overplot Item:
Assumed Ueq
Ueq
Dissipation, Ueq not achieved
Dissipation, Ueq achieved
Dissipation, Ueq assumed
Hydrostatic Line
Advanced Cone Penetration Test Plots with Ic, Su(Nkt),
Phi, and N1(60)Ic
The reported coordinates were acquired from consumer grade GPS equipment and are only approximate locations. The coordinates should not be used for design purposes. 0 50010000
5 10
15 20
25 30
35 40
45 50
55 60
qt (tsf)
Depth (feet)
0 501000u (ft)
0.02.04.0Ic (PKR 2009)
204060Phi (deg)
01234Su (Nkt) (tsf)
050100150N160 (Ic RW1998) (bpf)
ENGEOJob No: 24-56-27871Date: 2024-06-20 08:13Site: 10857 Linda Vista DriveSounding: 1-CPT1Cone: 1061:T1500F15U35 Max Depth: 17.800 m / 58.40 ftDepth Inc: 0.025 m / 0.082 ftAvg Int: Every PointFile: 24-56-27871_SP01.CORUnit Wt: SBTQtn (PKR2009)Su Nkt/Ndu: 15.0 / 6.0SBT: Robertson, 2009 and 2010Coords: (UTM Zone 10 North) N: 4129708m E: 583221m Refusal
Refusal
Refusal
Refusal
Refusal
Refusal
Overplot Item:
Assumed Ueq
Ueq
Dissipation, Ueq not achieved
Dissipation, Ueq achieved
Dissipation, Ueq assumed
Hydrostatic Line
N(60)Ic
Su(Ndu)
The reported coordinates were acquired from consumer grade GPS equipment and are only approximate locations. The coordinates should not be used for design purposes. 0 50010000
5 10
15 20
25 30
35 40
45 50
55 60
qt (tsf)
Depth (feet)
0 501000u (ft)
0.02.04.0Ic (PKR 2009)
204060Phi (deg)
01234Su (Nkt) (tsf)
050100150N160 (Ic RW1998) (bpf)
ENGEOJob No: 24-56-27871Date: 2024-06-20 11:05Site: 10857 Linda Vista DriveSounding: 1-CPT2Cone: 1061:T1500F15U35 Max Depth: 2.825 m / 9.27 ftDepth Inc: 0.025 m / 0.082 ftAvg Int: Every PointFile: 24-56-27871_CP02.CORUnit Wt: SBTQtn (PKR2009)Su Nkt/Ndu: 15.0 / 6.0SBT: Robertson, 2009 and 2010Coords: (UTM Zone 10 North) N: 4129728m E: 583270m Refusal
Refusal
Refusal
Refusal
Refusal
Refusal
Overplot Item:
Assumed Ueq
Ueq
Dissipation, Ueq not achieved
Dissipation, Ueq achieved
Dissipation, Ueq assumed
Hydrostatic Line
N(60)Ic
Su(Ndu)
The reported coordinates were acquired from consumer grade GPS equipment and are only approximate locations. The coordinates should not be used for design purposes. 0 50010000
5 10
15 20
25 30
35 40
45 50
55 60
qt (tsf)
Depth (feet)
0 501000u (ft)
0.02.04.0Ic (PKR 2009)
204060Phi (deg)
01234Su (Nkt) (tsf)
050100150N160 (Ic RW1998) (bpf)
ENGEOJob No: 24-56-27871Date: 2024-06-20 11:24Site: 10857 Linda Vista DriveSounding: 1-CPT2BCone: 1061:T1500F15U35 Max Depth: 11.125 m / 36.50 ftDepth Inc: 0.025 m / 0.082 ftAvg Int: Every PointFile: 24-56-27871_CP02B.CORUnit Wt: SBTQtn (PKR2009)Su Nkt/Ndu: 15.0 / 6.0SBT: Robertson, 2009 and 2010Coords: (UTM Zone 10 North) N: 4129727m E: 583269m Refusal
Refusal
Refusal
Refusal
Refusal
Refusal
Overplot Item:
Assumed Ueq
Ueq
Dissipation, Ueq not achieved
Dissipation, Ueq achieved
Dissipation, Ueq assumed
Hydrostatic Line
N(60)Ic
Su(Ndu)
The reported coordinates were acquired from consumer grade GPS equipment and are only approximate locations. The coordinates should not be used for design purposes. 0 50010000
5 10
15 20
25 30
35 40
45 50
55 60
qt (tsf)
Depth (feet)
0 501000u (ft)
0.02.04.0Ic (PKR 2009)
204060Phi (deg)
01234Su (Nkt) (tsf)
050100150N160 (Ic RW1998) (bpf)
ENGEOJob No: 24-56-27871Date: 2024-06-20 13:10Site: 10857 Linda Vista DriveSounding: 1-CPT3Cone: 1061:T1500F15U35 Max Depth: 12.600 m / 41.34 ftDepth Inc: 0.025 m / 0.082 ftAvg Int: Every PointFile: 24-56-27871_CP03.CORUnit Wt: SBTQtn (PKR2009)Su Nkt/Ndu: 15.0 / 6.0SBT: Robertson, 2009 and 2010Coords: (UTM Zone 10 North) N: 4129668m E: 583245m Refusal
Refusal
Refusal
Refusal
Refusal
Refusal
Overplot Item:
Assumed Ueq
Ueq
Dissipation, Ueq not achieved
Dissipation, Ueq achieved
Dissipation, Ueq assumed
Hydrostatic Line
N(60)Ic
Su(Ndu)
The reported coordinates were acquired from consumer grade GPS equipment and are only approximate locations. The coordinates should not be used for design purposes. 0 50010000
5 10
15 20
25 30
35 40
45 50
55 60
qt (tsf)
Depth (feet)
0 501000u (ft)
0.02.04.0Ic (PKR 2009)
204060Phi (deg)
01234Su (Nkt) (tsf)
050100150N160 (Ic RW1998) (bpf)
ENGEOJob No: 24-56-27871Date: 2024-06-20 12:23Site: 10857 Linda Vista DriveSounding: 1-CPT4Cone: 1061:T1500F15U35 Max Depth: 13.550 m / 44.45 ftDepth Inc: 0.025 m / 0.082 ftAvg Int: Every PointFile: 24-56-27871_CP04.CORUnit Wt: SBTQtn (PKR2009)Su Nkt/Ndu: 15.0 / 6.0SBT: Robertson, 2009 and 2010Coords: (UTM Zone 10 North) N: 4129677m E: 583314m Target Depth
Target Depth
Target Depth
Target Depth
Target Depth
Target Depth
Overplot Item:
Assumed Ueq
Ueq
Dissipation, Ueq not achieved
Dissipation, Ueq achieved
Dissipation, Ueq assumed
Hydrostatic Line
N(60)Ic
Su(Ndu)
Soil Behavior Type (SBT) Scatter Plots
ENGEOJob No: 24-56-27871Date: 2024-06-20 08:13Site: 10857 Linda Vista DriveSounding: 1-CPT1Cone: 1061:T1500F15U35 Legend
Sensitive, Fine Grained
Organic Soils
Clays
Silt Mixtures
Sand Mixtures
Sands
Gravelly Sand to Sand
Stiff Sand to Clayey Sand
Very Stiff Fine Grained
Depth Ranges
>0.0 to 5.0 ft
>5.0 to 10.0 ft
>10.0 to 15.0 ft
>15.0 to 20.0 ft
>20.0 to 25.0 ft
>25.0 to 30.0 ft
>30.0 to 35.0 ft
>35.0 to 40.0 ft
>40.0 to 45.0 ft
>45.0 to 50.0 ft
>50.0 ft
1 2345
6 7 8 9
Qtn,cs = 70
Ic = 2.6
0.10 1.0 10.01.0
10.0 100
1000
Fr (%)
Qtn
Qtn Chart (PKR 2009)
Legend
CCS (Cont. sensitive clay like)
CC (Cont. clay like)
TC (Cont. transitional)
SC (Cont. sand like)
CD (Dil. clay like)
TD (Dil. transitional)
SD (Dil. sand like)
CCS CC
TCSC CDTDSD
0.10 1.0 10.01.0
10.0 100
1000
Fr (%)
Qtn
Modified SBTn (PKR 2016)
Legend
Sensitive Fines
Organic Soil
Clay
Silty Clay
Clayey Silt
Silt
Sandy Silt
Silty Sand/Sand
Sand
Gravelly Sand
Stiff Fine Grained
Cemented Sand
1 2
345678910 1112
0.02.04.06.08.01.0 10.0
100
1000
Rf(%)
qt (bar)
Standard SBT Chart (UBC 1986)
ENGEOJob No: 24-56-27871Date: 2024-06-20 11:05Site: 10857 Linda Vista DriveSounding: 1-CPT2Cone: 1061:T1500F15U35 Legend
Sensitive, Fine Grained
Organic Soils
Clays
Silt Mixtures
Sand Mixtures
Sands
Gravelly Sand to Sand
Stiff Sand to Clayey Sand
Very Stiff Fine Grained
Depth Ranges
>0.0 to 5.0 ft
>5.0 to 10.0 ft
>10.0 to 15.0 ft
>15.0 to 20.0 ft
>20.0 to 25.0 ft
>25.0 to 30.0 ft
>30.0 to 35.0 ft
>35.0 to 40.0 ft
>40.0 to 45.0 ft
>45.0 to 50.0 ft
>50.0 ft
1 2345
6 7 8 9
Qtn,cs = 70
Ic = 2.6
0.10 1.0 10.01.0
10.0 100
1000
Fr (%)
Qtn
Qtn Chart (PKR 2009)
Legend
CCS (Cont. sensitive clay like)
CC (Cont. clay like)
TC (Cont. transitional)
SC (Cont. sand like)
CD (Dil. clay like)
TD (Dil. transitional)
SD (Dil. sand like)
CCS CC
TCSC CDTDSD
0.10 1.0 10.01.0
10.0 100
1000
Fr (%)
Qtn
Modified SBTn (PKR 2016)
Legend
Sensitive Fines
Organic Soil
Clay
Silty Clay
Clayey Silt
Silt
Sandy Silt
Silty Sand/Sand
Sand
Gravelly Sand
Stiff Fine Grained
Cemented Sand
1 2
345678910 1112
0.02.04.06.08.01.0 10.0
100
1000
Rf(%)
qt (bar)
Standard SBT Chart (UBC 1986)
ENGEOJob No: 24-56-27871Date: 2024-06-20 11:24Site: 10857 Linda Vista DriveSounding: 1-CPT2BCone: 1061:T1500F15U35 Legend
Sensitive, Fine Grained
Organic Soils
Clays
Silt Mixtures
Sand Mixtures
Sands
Gravelly Sand to Sand
Stiff Sand to Clayey Sand
Very Stiff Fine Grained
Depth Ranges
>0.0 to 5.0 ft
>5.0 to 10.0 ft
>10.0 to 15.0 ft
>15.0 to 20.0 ft
>20.0 to 25.0 ft
>25.0 to 30.0 ft
>30.0 to 35.0 ft
>35.0 to 40.0 ft
>40.0 to 45.0 ft
>45.0 to 50.0 ft
>50.0 ft
1 2345
6 7 8 9
Qtn,cs = 70
Ic = 2.6
0.10 1.0 10.01.0
10.0 100
1000
Fr (%)
Qtn
Qtn Chart (PKR 2009)
Legend
CCS (Cont. sensitive clay like)
CC (Cont. clay like)
TC (Cont. transitional)
SC (Cont. sand like)
CD (Dil. clay like)
TD (Dil. transitional)
SD (Dil. sand like)
CCS CC
TCSC CDTDSD
0.10 1.0 10.01.0
10.0 100
1000
Fr (%)
Qtn
Modified SBTn (PKR 2016)
Legend
Sensitive Fines
Organic Soil
Clay
Silty Clay
Clayey Silt
Silt
Sandy Silt
Silty Sand/Sand
Sand
Gravelly Sand
Stiff Fine Grained
Cemented Sand
1 2
345678910 1112
0.02.04.06.08.01.0 10.0
100
1000
Rf(%)
qt (bar)
Standard SBT Chart (UBC 1986)
ENGEOJob No: 24-56-27871Date: 2024-06-20 13:10Site: 10857 Linda Vista DriveSounding: 1-CPT3Cone: 1061:T1500F15U35 Legend
Sensitive, Fine Grained
Organic Soils
Clays
Silt Mixtures
Sand Mixtures
Sands
Gravelly Sand to Sand
Stiff Sand to Clayey Sand
Very Stiff Fine Grained
Depth Ranges
>0.0 to 5.0 ft
>5.0 to 10.0 ft
>10.0 to 15.0 ft
>15.0 to 20.0 ft
>20.0 to 25.0 ft
>25.0 to 30.0 ft
>30.0 to 35.0 ft
>35.0 to 40.0 ft
>40.0 to 45.0 ft
>45.0 to 50.0 ft
>50.0 ft
1 2345
6 7 8 9
Qtn,cs = 70
Ic = 2.6
0.10 1.0 10.01.0
10.0 100
1000
Fr (%)
Qtn
Qtn Chart (PKR 2009)
Legend
CCS (Cont. sensitive clay like)
CC (Cont. clay like)
TC (Cont. transitional)
SC (Cont. sand like)
CD (Dil. clay like)
TD (Dil. transitional)
SD (Dil. sand like)
CCS CC
TCSC CDTDSD
0.10 1.0 10.01.0
10.0 100
1000
Fr (%)
Qtn
Modified SBTn (PKR 2016)
Legend
Sensitive Fines
Organic Soil
Clay
Silty Clay
Clayey Silt
Silt
Sandy Silt
Silty Sand/Sand
Sand
Gravelly Sand
Stiff Fine Grained
Cemented Sand
1 2
345678910 1112
0.02.04.06.08.01.0 10.0
100
1000
Rf(%)
qt (bar)
Standard SBT Chart (UBC 1986)
ENGEOJob No: 24-56-27871Date: 2024-06-20 12:23Site: 10857 Linda Vista DriveSounding: 1-CPT4Cone: 1061:T1500F15U35 Legend
Sensitive, Fine Grained
Organic Soils
Clays
Silt Mixtures
Sand Mixtures
Sands
Gravelly Sand to Sand
Stiff Sand to Clayey Sand
Very Stiff Fine Grained
Depth Ranges
>0.0 to 5.0 ft
>5.0 to 10.0 ft
>10.0 to 15.0 ft
>15.0 to 20.0 ft
>20.0 to 25.0 ft
>25.0 to 30.0 ft
>30.0 to 35.0 ft
>35.0 to 40.0 ft
>40.0 to 45.0 ft
>45.0 to 50.0 ft
>50.0 ft
1 2345
6 7 8 9
Qtn,cs = 70
Ic = 2.6
0.10 1.0 10.01.0
10.0 100
1000
Fr (%)
Qtn
Qtn Chart (PKR 2009)
Legend
CCS (Cont. sensitive clay like)
CC (Cont. clay like)
TC (Cont. transitional)
SC (Cont. sand like)
CD (Dil. clay like)
TD (Dil. transitional)
SD (Dil. sand like)
CCS CC
TCSC CDTDSD
0.10 1.0 10.01.0
10.0 100
1000
Fr (%)
Qtn
Modified SBTn (PKR 2016)
Legend
Sensitive Fines
Organic Soil
Clay
Silty Clay
Clayey Silt
Silt
Sandy Silt
Silty Sand/Sand
Sand
Gravelly Sand
Stiff Fine Grained
Cemented Sand
1 2
345678910 1112
0.02.04.06.08.01.0 10.0
100
1000
Rf(%)
qt (bar)
Standard SBT Chart (UBC 1986)
Pore Pressure Dissipation Test (PPDT) Summary and
PPDT Plots
Job No: 24-56-27871
Client: ENGEO, Inc.
Project: 10857 Linda Vista Drive
Start Date: 2024-06-20
End Date: 2024-06-20
CPTu PORE PRESSURE DISSIPATION SUMMARY
Sounding ID File Name Cone Area
(cm2)
Duration
(s)
Test
Depth
(ft)
Estimated
Equilibrium Pore
Pressure Ueq
(ft)
Calculated
Phreatic Surface
(ft)
Refer to
Notation
Number
1-CPT1 24-57-27871_SP01 15 600 53.97 1
1-CPT2B 24-57-27871_CP02B 15 485 36.50 1
1-CPT3 24-57-27871_CP03 15 390 20.51 1
Totals 25 min
1. Equilibrium pore pressure not achieved.
Sheet 1 of 1
0 150 300 450 6000
10 20
30 40
Time (s)
Pore Pressure (ft)
ENGEOJob No:24-57-27871Date:06/20/2024 08:13Site:10857 Linda Vista DriveSounding:1-CPT1Cone:1061:T1500F15U35 Area=15 cm² Trace Summary: Filename:24-57-27871_SP01.ppd2Depth:16.450 m / 53.969 ftDuration:600.0 s u Min:3.7 ftu Max:26.9 ftu Final:3.7 ft 0 150 300 450 600
0 10
20 30
0 -10 Time (s)
Pore Pressure (ft)
ENGEOJob No:24-57-27871Date:06/20/2024 11:24Site:10857 Linda Vista DriveSounding:1-CPT2BCone:1061:T1500F15U35 Area=15 cm² Trace Summary: Filename:24-57-27871_CP02B.ppd2Depth:11.125 m / 36.499 ftDuration:485.0 s u Min:-6.7 ftu Max:19.0 ftu Final:-0.1 ft 0 100 200 300 400
0 10
20 30
0 -10 Time (s)
Pore Pressure (ft)
ENGEOJob No:24-57-27871Date:06/20/2024 12:23Site:10857 Linda Vista DriveSounding:1-CPT4Cone:1061:T1500F15U35 Area=15 cm² Trace Summary: Filename:24-57-27871_CP04.ppd2Depth:6.250 m / 20.505 ftDuration:390.0 s u Min:-2.1 ftu Max:25.8 ftu Final:-2.1 ft Seismic Cone Penetration Test (SCPTu) Tabular Results
Job No: 24-56-27871
Client: ENGEO
Project: 10857 Linda Vista Drive
Sounding ID: 1-CPT1
Date: 6/20/2024
Seismic Source: Beam
Seismic Offset (ft): 1.97
Source Depth (ft): 0.00
Geophone Offset (ft): 0.66
SCPTu SHEAR WAVE VELOCITY TEST RESULTS - Vs
Tip
Depth
(ft)
Geophone
Depth
(ft)
Ray
Path
(ft)
Ray Path
Difference
(ft)
Travel Time
Interval
(ms)
Interval
Velocity
(ft/s)
2.79 2.13 3.91
6.07 5.41 6.33 2.42 3.01 804
9.35 8.69 9.29 2.96 3.21 923
12.63 11.97 12.42 3.12 2.73 1143
15.91 15.26 15.60 3.19 2.48 1287
19.19 18.54 18.82 3.22 2.39 1347
22.47 21.82 22.06 3.24 2.10 1543
25.75 25.10 25.31 3.25 1.78 1829
29.04 28.38 28.57 3.26 1.78 1834
32.25 31.59 31.76 3.20 1.64 1949
35.60 34.94 35.09 3.33 1.91 1741
38.88 38.22 38.36 3.27 1.90 1721
42.16 41.50 41.63 3.27 1.72 1900
45.44 44.78 44.90 3.27 1.71 1916
48.72 48.06 48.18 3.27 1.71 1916
52.00 51.35 51.45 3.27 1.76 1863
55.28 54.63 54.72 3.27 2.06 1590
58.40 57.74 57.84 3.11 1.65 1886
Sheet 1 of 1
SCPTu Test Plots
The reported coordinates were acquired from consumer grade GPS equipment and are only approximate locations. The coordinates should not be used for design purposes. 0 50010000
5 10
15 20
25 30
35 40
45 50
55 60
qt (tsf)
Depth (feet)
0.0 5.0 10.0fs (tsf)
0 50 1000 u (ft)
0 12502500Vs (ft/s)
ENGEOJob No: 24-56-27871Date: 2024-06-20 08:13Site: 10857 Linda Vista DriveSounding: 1-CPT1Cone: 1061:T1500F15U35 Max Depth: 17.800 m / 58.40 ftDepth Inc: 0.025 m / 0.082 ftAvg Int: Every PointFile: 24-56-27871_SP01.CORUnit Wt: SBTQtn (PKR2009)SBT: Robertson, 2009 and 2010Coords: (UTM Zone 10 North) N: 4129708m E: 583221m Ueq(ft)
Refusal
Refusal
Refusal
Refusal
Overplot Item:
Assumed Ueq
Ueq
Dissipation, Ueq not achieved
Dissipation, Ueq achieved
Dissipation, Ueq assumed
Hydrostatic Line
SCPTu Velocity Wave Traces
Job No: 24-56-27871 Client: ENGEO Project: 10857 Linda Vista DriveAnalysis: Shear Wave Sounding: 1-CPT1 Filter: 10857 Linda Vist Date: 2024-06-20 Cone: 1061:T1500F15U35
0 20 40 60 80 100
0 20
40 60
TIME (ms)
DEPTH (ft)
SUPPORTING DOCUMENTS AND MATERIALS
The documents and materials listed below are included in the report:
Methodology Statements
Cone Penetration Digital File Formats
Description of Methods for Calculated CPTu Geotechnical Parameters Calibration Records
Methodology Statements
Cone penetration tests (CPTu) are conducted using an integrated electronic piezocone penetrometer and data acquisition system manufactured by Adara Systems Ltd., a subsidiary of ConeTec.
ConeTec’s piezocone penetrometers are compression type designs in which the tip and friction sleeve load cells are independent and have separate load capacities. The piezocones use strain gauged load cells for tip and sleeve friction and a strain gauged diaphragm type transducer for recording pore pressure. The piezocones also have a platinum resistive temperature device (RTD) for monitoring the temperature of the sensors, an accelerometer type dual axis inclinometer and two geophone sensors for recording seismic signals. All signals are amplified and measured with minimum sixteen-bit resolution down hole within the cone body, and the signals are sent to the surface using a high bandwidth, error corrected digital interface through a shielded cable.
ConeTec penetrometers are manufactured with various tip, friction and pore pressure capacities in both 10 cm 2 and 15 cm2
tip base area configurations in order to maximize signal resolution for various soil conditions. The specific piezocone used for each test is described in the CPT summary table. The 15 cm 2 penetrometers do not require friction reducers as they have a diameter larger than the deployment rods. The 10 cm2 piezocones use a friction reducer consisting of a rod adapter extension behind the main cone body with an enlarged cross sectional area (typically 44 millimeters diameter over a length of 32 millimeters with tapered leading and trailing edges) located at a distance of 585 millimeters above the cone tip.
The penetrometers are designed with equal end area friction sleeves, a net end area ratio of 0.8 and cone tips with a 60 degree apex angle.
All ConeT
ec piezocones can record pore pressure at various locations. Unless otherwise noted, the pore pressure filter is located directly behind the cone tip in the “u 2” position (ASTM Type 2). The filter is six millimeters thick, made of porous plastic (polyethylene) having an average pore size of 125 microns (90-160 microns). The function of the filter is to allow rapid movements of extremely small volumes of water needed to activate the pressure transducer while preventing soil ingress or blockage.
The piezocone penetrometers are manufactured with dimensions, tolerances and sensor characteristics that are in general accordance with the current ASTM D5778 standard. ConeTec’s calibration criteria also meets or exceeds those of the current ASTM D5778 standard. An illustration of the piezocone penetrometer is presented in Figure CPTu.
METHODOLOGY STATEMENTS
CONE PENETRATION TEST (CPTu) - eSeries
The ConeTec data acquisition system consists of a Windows based computer, signal interface box, and power supply. The signal interface combines depth increment signals, seismic trigger signals and the downhole digital data. This combined data is then sent to the Windows based computer for collection and presentation. The data is recorded at fixed depth increments using a depth encoder that is either portable or integrated into the rig. The typical recording interval is 2.5 centimeters; custom recording intervals are possible.
The system displays the CPTu data in real time and records the following parameters to a storage media during penetration:
• Depth
• Uncorrected tip resistance (qc)
• Sleeve friction (fs)
• Dynamic pore pressure (u)
• Additional sensors such as resistivity
, passive gamma, ultra violet induced fluorescence, if applicable All testing is performed in accordance to ConeTec’s CPTu operating procedures which are in general accordance with the current ASTM D5778 standard.
Figure CPTu. Piezocone Penetrometer (15 cm2)
Prior to the start of a CPTu sounding a suitable cone is selected, the cone and data acquisition system are powered on, the pore pressure system is saturated with silicone oil and the baseline readings are recorded with the cone hanging freely in a vertical position.
The CPTu is conducted at a steady rate of two centimeters per second, within acceptable tolerances. Typically one meter length rods with an outer diameter of 1.5 inches are added to advance the cone to the sounding termination depth. After cone retraction final baselines are recorded.
Additional information pertaining to ConeTec’s cone penetration testing procedures:
• Each filter is saturated in silicone oil under vacuum pressure prior to use • Baseline readings are compared to previous readings
• Soundings are terminated at the client’
s target depth or at a depth where an obstruction is encountered, excessive rod flex occurs, excessive inclination occurs, equipment damage is likely to take place, or a dangerous working environment arises
• Differ
ences between initial and final baselines are calculated to ensure zero load offsets have not occurred and to ensure compliance with ASTM standards
The interpretation of
piezocone data for this report is based on the corrected tip resistance (qt), sleeve friction (fs) and pore water pressure (u). The interpretation of soil type is based on the correlations developed by Robertson, P.K., 2010. The Soil Behavior Type (SBT) classification chart developed by Robertson, P.K., 2010 is presented in Figure SBT. It should be noted that it is not always possible to accurately identify a soil behavior type based on these parameters. In these situations, experience, judgment and an assessment of other parameters may be used to infer soil behavior type.
Figure SBT. Non-Normalized Soil Behavior Type Classification Chart (SBT)
The recorded tip resistance (qc) is the total force acting on the piezocone tip divided by its base area. The tip resistance is corrected for pore pressure effects and termed corrected tip resistance (qt) according to the following expression presented in Robertson et al. (1986):
qt = qc + (1-a) • u2
where: qt is the corrected tip resistance
qc is the recorded tip resistance
u2 is the recorded dynamic pore pressure behind the tip (u2 position) a is the Net Area Ratio for the piezocone (0.8 for ConeTec probes) The
sleeve friction (fs) is the frictional force on the sleeve divided by its surface area. As all ConeTec piezocones have equal end area friction sleeves, pore pressure corrections to the sleeve data are not required.
The dynamic pore pressure (u) is a measure of the pore pressures generated during cone penetration. To record equilibrium pore pressure, the penetration must be stopped to allow the dynamic pore pressures to stabilize. The rate at which this occurs is predominantly a function of the permeability of the soil and the diameter of the cone.
The friction ratio (Rf) is a calculated parameter. It is defined as the ratio of sleeve friction to the tip resistance expressed as a percentage. Generally, saturated cohesive soils have low tip resistance, high friction ratios and generate large excess pore water pressures. Cohesionless soils have higher tip resistances, lower friction ratios and do not generate significant excess pore water pressure.
For additional information on CPTu interpretations and calculated geotechnical parameters, refer to Robertson et al. (1986), Lunne et al. (1997), Robertson (2009), Mayne (2013, 2014) and Mayne and Peuchen (2012).
REFERENCES
ASTM D5778-20, 2020, “Standard Test Method for Performing Electronic Friction Cone and Piezocone Penetration Testing of Soils”, ASTM International, West Conshohocken, PA. DOI: 10.1520/D5778-20.
Lunne, T., Robertson, P.K. and Powell, J. J. M., 1997, “Cone Penetration Testing in Geotechnical Practice”, Blackie Academic and Professional.
Mayne, P.W., 2013, “Evaluating yield stress of soils from laboratory consolidation and in-situ cone penetration tests”, Sound Geotechnical Research to Practice (Holtz Volume) GSP 230, ASCE, Reston/VA: 406-420. DOI: 10.1061/9780784412770.027.
Mayne, P.W. and Peuchen, J., 2012, “Unit weight trends with cone resistance in soft to firm clays”, Geotechnical and Geophysical Site Characterization 4, Vol. 1 (Proc. ISC-4, Pernambuco), CRC Press, London: 903-910.
Mayne, P.W., 2014, “Interpretation of geotechnical parameters from seismic piezocone tests”, CPT’14 Keynote Address, Las Vegas, NV, May 2014.
Robertson, P.K., Campanella, R.G., Gillespie, D. and Greig, J., 1986, “Use of Piezometer Cone Data”, Proceedings of InSitu 86, ASCE Specialty Conference, Blacksburg, Virginia.
Robertson, P.K., 2009, “Interpretation of cone penetration tests – a unified approach”, Canadian Geotechnical Journal, Volume 46: 1337- 1355. DOI: 10.1139/T09-065.
Robertson, P.K., 2010. Soil behavior type from the CPT: an update. 2nd International Symposium on Cone Penetration Testing, CPT’10, Huntington Beach, CA, USA
The cone penetration test is halted at specific depths to carry out pore pressure dissipation (PPD) tests, shown in Figure PPD-1. For each dissipation test the cone and rods are decoupled from the rig and the data acquisition system measures and records the variation of the pore pressure (u) with time (t).
Figure PPD-1. Pore pressure dissipation test setup
Pore pressure dissipation data can be interpreted to provide estimates of ground water conditions, permeability, consolidation characteristics and soil behavior.
The typical shapes of
dissipation curves shown in Figure PPD-2 are very useful in assessing soil type, drainage, in situ pore pressure and soil properties. A flat curve that stabilizes quickly is typical of a freely draining sand. Undrained soils such as clays will typically show positive excess pore pressure and have long dissipation times. Dilative soils will often exhibit dynamic pore pressures below equilibrium that then rise over time. Overconsolidated fine-grained soils will often exhibit an initial dilatory response where there is an initial rise in pore pressure before reaching a peak and dissipating.
Figure PPD-2. Pore pressure dissipation curve examples
PORE PRESSURE DISSIPATION TEST
In order to interpret the equilibrium pore pressure (u eq) and the apparent phreatic surface, the pore pressure should be monitored until such time as there is no variation in pore pressure with time as shown for each curve in Figure PPD-2.
Shear wave velocity (Vs) testing is performed in conjunction with the piezocone penetration test (SCPTu) in order to collect interval velocities. For some projects seismic compression wave velocity (Vp) testing is also performed.
ConeTec’s piezocone penetrometers are manufactured with one horizontally active geophone (28 hertz) and one vertically active geophone (28 hertz). Both geophones are rigidly mounted in the body of the cone penetrometer, 0.2 meters behind the cone tip. The vertically mounted geophone is more sensitive to compression waves.
Shear waves are typically generated by using an impact hammer horizontally striking a beam that is held in place by a normal load. In some instances, an auger source or an imbedded impulsive source may be used for both shear waves and compression waves.
The hammer and beam act as a contact trigger that initiates the recording of the seismic wave traces.
For impulsive devices
an accelerometer trigger may be used. The traces are recorded in the memory of the cone using a fast analog to
digital converter. The seismic trace is then transmitted digitally uphole to a Windows based computer through a signa
l interface box for recording and analysis. An illustration of the shear wave testing configuration is presented in Figure SCPT
u-1.
Figure SCPTu-1. Illustration of the SCPTu system
All testing is performed in accordance to ConeTec’s SCPTu operating procedures which are in general accordance with the current ASTM D5778 and ASTM D7400 standards.
Prior to the start of a SCPTu sounding, the procedures described in the Cone Penetration Test section are followed. In addition, the active axis of the geophone is aligned parallel to the beam (or source) and the horizontal offset between the cone and the source is measured and recorded.
Prior to recording seismic waves at each test depth, cone penetration is stopped and the rods are decoupled from the rig to avoid transmission of rig energy down the rods. Typically, five wave traces for each orientation are recorded for quality control and uncertainty analysis purposes. After reviewing wave traces for consistency the cone is pushed to the next test depth (typically one meter intervals or as requested by the client). Figure SCPTu-2 presents an illustration of a SCPTu test.
For additional information on seismic cone penetration testing refer to Robertson et al. (1986).
SEISMIC CONE PENETRATION TEST (SCPTu) - eSeries
Figure SCPTu-2. Illustration of a seismic cone penetration test For the determination of interval travel times the wave traces from all depths are displayed in analysis software.
The results of the interval picks are supplied in the relevant appendix of this report. Standard practice for ConeTec is to record five wave traces for each source direction at each test depth. Outlier impacts are identified in the field and the impacts are repeated. For the final wave trace profile, the traces are stacked in the time domain to display a single average trace.
Calculation of the interval velocities are performed by visually picking a common feature (e.g. the first characteristic peak, trough, or crossover) on all of the recorded wave sets and taking the difference in ray path divided by the time difference between subsequent features. Ray path is defined as the straight line distance from the seismic source to the geophone, accounting for beam offset, source depth and geophone offset from the cone tip.
In some cases, usually for shear wave velocity testing, more than one characteristic marker may be used. If there is an overlap between different sets of characteristic markers, then the average time value for those sets of interval times is applied to the determination of velocity.
Ideally, all depths are used for the determination of the velocity profile. However, an interval may be skipped if there is some ambiguity or quality concern with a particular depth, resulting in a larger interval.
Tabular velocity results and SCPTu plots are presented in the relevant appendix.
For all SCPTu soundings that have achieved a depth of at least 100 feet (30 meters), the average shear wave velocity to a depth of 100 feet (̅vs)
has been calculated and provided for all applicable soundings using the following equation presented in ASCE (2010).
̅vs=
∑ dii=1
∑ di
vsi
n
i=1
where: ̅vs = average shear wave velocity ft/s (m/s) di = the thickness of any layer between 0 and 100 ft (30 m) vsi = the shear wave velocity in ft/s (m/s)
n
i=1∑ di = the total thickness of all layers between 0 and 100 ft (30 m) Average shear wave velocity, ̅vs is also referenced to Vs100 or Vs30.
The layer travel times refers to the travel times propagating in the vertical direction, not the measured travel times from an offset source.
REFERENCES
American Society of Civil Engineers (ASCE), 2010, “Minimum Design Loads for Buildings and Other Structures”, Standard ASCE/ SEI 7-10, American Society of Civil Engineers, ISBN 978-0-7844-1085-1, Reston, Virginia. DOI: 10.1061/9780784412916.
ASTM D5778-20, 2020, “Standard Test Method for Performing Electronic Friction Cone and Piezocone Penetration Testing of Soils”, ASTM International, West Conshohocken, PA. DOI: 10.1520/D5778-20.
ASTM D7400/D7400M-19, 2019, “Standard Test Methods for Downhole Seismic Testing”, ASTM International, West Conshohocken, PA. DOI: 10.1520/D7400_D7400M-19.
Robertson, P.K., Campanella, R.G., Gillespie D and Rice, A., 1986, “Seismic CPT to Measure In-Situ Shear Wave Velocity”, Journal of Geotechnical Engineering ASCE, Vol. 112, No. 8: 791-803. DOI: 10.1061/(ASCE)0733-9410(1986)112:8(791).
Cone Penetration Digital File Formats
CPT Data Files (COR Extension)
ConeTec CPT data files are stored in ASCII text files that are readable by almost any text editor. ConeTec file names start with the job number (which includes the two digit year number) an underscore as a separating character, followed by two letters based on the type of test and the sounding ID. The last character position is reserved for an identifier letter (such as b, c, d etc) used to uniquely distinguish multiple soundings at the same location. The CPT sounding file has the extension COR. As an example, for job number 21-02-00001 the first CPT sounding will have file name 21-02-00001_CP01.COR The sounding (COR) file consists of the following components:
1. Two lines of header information
2. Data records
3. End of data marker
4. Units information
Header Lines
Line 1: Columns 1-6 may be blank or may indicate the version number of the recording software Columns 7-21 contain the sounding Date and Time (Date is MM:DD:YY) Columns 23-38 contain the sounding Operator
Columns 51-100 contain extended Job Location information Line 2: Columns 1-16 contain the Job Location
Columns 17-32 contain the Cone ID
Columns 33-47 contain the sounding number
Columns 51-100 may contain extended sounding ID information Data Records
The data records contain 4 or more columns of data in floating point format. A comma and spaces separate each data item:
Column 1: Sounding Depth (meters)
Column 2: Tip (qc), recorded in units selected by the operator Column 3: Sleeve (fs), recorded in units selected by the operator Column 4: Dynamic pore pressure (u), recorded in units selected by the operator Column 5: Empty or may contain other requested data such as Gamma, Resistivity or UVIF data End of Data Marker
After the last line of data there is a line containing an ASCII 26 (CTL-Z) character (small rectangular shaped character) followed by a newline (carriage return / line feed). This is used to mark the end of data.
CONE PENETRATION DIGITAL
FILE FORMATS - eSeries
Units Information
The last section of the file contains information about the units that were selected for the sounding. A separator bar makes up the first line. The second line contains the type of units used for depth, qc, fs and u. The third line contains the conversion values required for ConeTec’s software to convert the recorded data to an internal set of base units (bar for qc, bar for fs and meters for u). Additional lines intended for internal ConeTec use may appear following the conversion values.
CPT Data Files (XLS Extension)
Excel format files of ConeTec CPT data are also generated from corresponding COR files. The XLS files have the same base file name as the COR file with a -BSC suffix. The information in the file is presented in table format and contains additional information about the sounding such as coordinate information, and tip net area ratio.
The BSCI suffix is given to XLS files which are enhanced versions of the BSC files and include the same data records in addition to inclination data collected for each sounding.
CPT Dissipation Files (XLS Extension)
Pore pressure dissipation files are provided in Excel format and contain each dissipation trace that exceeds a minimum duration (selected during post-processing) formatted column wise within the spreadsheet. The first column (Column A) contains the time in seconds and the second column (Column B) contains the time in minutes. Subsequent columns contain the dissipation trace data. The columns extend to the longest trace of the data set.
Detailed header information is provided at the top of the worksheet. The test depth in meters and feet, the number of points in the trace and the particular units are all presented at the top of each trace column.
CPT Dissipation files have the same naming convention as the CPT sounding files with a “–PPD” suffix.
Data Records
Each file will contain dissipation traces that exceed a minimum duration (selected during post-processing) in a particular column. The dissipation pore pressure values are typically recorded at varying time intervals throughout the trace; rapidly to start and increasing as the duration of the test lengthens. The test depth in meters and feet, the number of points in the trace and the trace number are identified at the top of each trace column.
Cone Type Designations
Cone ID Cone Description Tip Cross
Sect. Area (cm2)
Tip Capacity
(bar)
Sleeve Area
(cm2)**
Sleeve
Capacity (bar)
Pore Pressure
Capacity (bar)
EC### A15T1500F15U35 15 1500 225 15 35
EC### A15T375F10U35 15 375 225 10 35
EC### A10T1000F10U35 10 1000 150 10 35
### refers to the Cone ID number
**Outer Cylindrical Area
Description of Methods for Calculated CPT Geotechnical
Parameters
CALCULATED CPT GEOTECHNICAL PARAMETERS
A Detailed Description of the Methods Used in
ConeTec’s CPT Geotechnical Parameter
Calculation and Plotting Software
Revision SZW-Rev 18
Revised February 10, 2023
Prepared by Jim Greig, M.A.Sc, P.Eng (BC, AB, ON)
Limitations
The geotechnical parameter output was prepared specifically for the site and project named in the accompanying report subject to objectives , site conditions and criteria provided to ConeTec by the client. The output may not be relied upon by any other party or for any other site without the express written permission of ConeTec Group (ConeTec) or any of its affiliates . For this project, ConeTec has provide d site investigation services, prepared factual data reporting and produced geotechnical parameter calculations consistent with current best practices.
No other warranty, expressed or implied, is made.
To understand the calculations that have been performed and to be able to reproduce the calculated parameters the user is directed to the basic descriptions for the methods in this document and the detailed descriptions and their associated limitations and appropriateness in the technical references cited for each parameter.
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 1 | 19
ConeTec’s Calculated CPT Geotechnical Parameters as of February 10, 2023.
ConeTec’s CPT parameter calculation and plotting routine provides a tabular output of geotechnical parameters based on current published CPT correlations and is subject to change to reflect the current state of practice.
Due to drainage conditions and the basic assumptions and limitations of the corre lations, not all geotechnical parameters provided are considered applicable for all soil types . The results are presented only as a guide for geotechnical use and should be carefully examined for consideration in any geotechnical design. Reference to current literature is strongly recommended. ConeTec does not warranty the correctness or the applicability of any of the geotechnical parameters calculated by the program and does not assume liability for any use of the results in any design or review. For verification purposes we recommend that r epresentative hand calculations be done for any parameter that is critical for design purposes. The end user of the parameter output should also be fully aware of the techniques and the limitations of any method used by the program. The purpose of this document is to inform the user as to which methods were used and to direct the end user to the appropriate technical papers and/or publications for further reference.
The geotechnical parameter output was prepared sp ecifically for the site and project named in the accompanying report subject to objectives, site conditions and criteria provided to ConeTec by the client. The output may not be relied upon by any other party or for any other site without the express writ ten permission of ConeTec Group (ConeTec) or any of its affiliates.
The CPT calculations are based on values of tip resistance, sleeve friction and pore pressures considered at each data point or averaged over a user specified layer thickness (e.g., 0.20 m). Note that qt is the tip resistance corrected for pore pressure effects and qc is the recorded tip resistance. The corrected tip resistance (corrected using u 2 pore pressure values) is used for all calculations. Since all ConeTec cones have equal end area friction sleeves pore pressure corrections to sleeve friction, fs, are not performed.
Corrected tip resistance: qt = qc + (1-a) ٠ u2 (consistent units are required) where: qt is the corrected tip resistance
qc is the recorded tip resistance
u2 is the recorded dynamic pore pressure from behind the tip (u2 position) a is the Net Area Ratio for the cone (typically 0.80 for ConeTec cones)
The total stress calculations are based on soil unit weight values that have been assigned to the Soil Behavior Type (SBT) zones, from a user defined unit weight profile, by using a single uniform value throughout the profile, through unit weight estimation techniques described in various technical papers or from a combination of these methods .
The parameter output files indicate the method(s) used.
Effective vertical overburden stresses are calculated using the total stress and equilibrium pore pressure (ueq or uo) values derived from an assumed hydrostatic distribution of pore pressures below the water table or from a user defined equilibrium pore pressure profile (typically obtained from CPT dissipation tests) or a combination of the two.
For over water projects the stress effects of the column of water above the mudline are taken into account as is the appropriate unit weight of water. How this is done depends on where the instruments are zeroed (i.e. on deck or at the mudline). The parameter output files indicate the method(s) used.
A majority of parameter calculations are derived from or driven by results based on material types as determined by the various soil behavior type charts depicted in Figures 1 through 6. The parameter output files indicate the method(s) used.
The Soil Behavior Type classification chart shown in Figure 1 is the classic non -normalized SBT Chart developed at the University of British Columbia and reported in Robertson, Campanella, Gillespie and Greig (1986). Figure 2 shows the original normalized (linear method) SBTn chart developed by Robertson (1990). The Bq classification charts Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 2 | 19
shown in Figures 3a and 3b incorporate pore pressures into the SBT classification and are based on th e methods described in Robertson (1990). Many of these charts have been summarized in Lunne, Robertson and Powell (1997).
The Jefferies and Davies SBT chart shown in Figure 3c is based on th e techniques discussed in Jefferies and Davies (1993) which introduced the concept of the Soil Behavior Type Index parameter, Ic. Take note that the Ic parameter developed by Robertson and Fear (1995) and Robertson and Wride (19 98) is similar in concept but uses a slightly different calculation method than that defined by Jefferies and Davies (1993) as the latter incorporates pore pressure in their technique through the use of the Bq parameter. The normalized Qtn SBT chart shown in Figure 4 is based on the work by Robertson (2009) utilizing a variable stress ratio exponent, n, for normalization based on a slightly modified redefinition and iterative approach for I c. The boundary curves drawn on the chart are based on the work described in Robertson (2010).
Figure 5 shows a revised 1986 SBT Chart presented to CPT’10 by Robertson (2010b). It is known as the Updated non- normalized Soil Behavior Chart (also referred to as the Rev SBT Chart (PKR2010) in our output files). This chart was produced to be more in line with all post -1986 Robertson charts having the same 9 soil type zones, a log10 axis for friction ratio, Rf in this case, and a unitless tip resistance axis.
Figure 6 shows a revised behavior based chart by Robertson (2016) depicting contractive-dilative zones. As the zones represent material behavior rather than soil gradation ConeTec has chosen a set of zone colors that are less likely to be confused with material type colors from previous SBT charts. These colors differ from those used by Dr.
Robertson. A green palette was selected for the dilative (desirable) side of the chart and a red palette for the contractive side of the chart.
𝑅𝑓 = (𝑓𝑠
𝑞𝑡) ∙ 100%
Figure 1. Non-normalized Soil Behavior Type Classification Chart (SBT) Friction Ratio (%), Rf
Cone Bearing (bar), qt
1000
10 1
0 1 2 3 4 5 6 7 8
100
3 1
4 5
6 7
8 9
10 12
11 2
Zone qt / N Soil Behavior Type
1 2
3 4
5 6
7 8
9 10
11 12
sensitive fine grained
organic material
clay
silty clay to clay
clayey silt to silty clay
sandy silt to clayey silt
silty sand to sandy silt
sand to silty sand
sand
gravelly sand to sand
very stiff fine grained *
sand to clayey sand *
* overconsolidated or cemented
2 1
1 1.5
2 2.5
3 4
5 6
1 2
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 3 | 19
Figure 2. Normalized Soil Behavior Type Classification Chart (SBTn)
Figure 3a. Alternate Soil Behavior Type Chart (SBT Bq): qt - Bq
Normalized Cone Resistance q-t vo
'vo
0.1 1
100
10 1000
1 10
Normalized Friction Ratio
1 2
3 4
5 6
7 8
9 fs x 100%q-t vo
Zone Normalized Soil Behavior Type
1 2
3 4
5 6
7 8
9 sensitive fine grained
organic material
clay to silty clay
clayey silt to silty clay
silty sand to sandy silt
clean sands to silty sands
gravelly sand to sand
very stiff sand to clayey sand
very stiff fine grained
Fr =
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 4 | 19
Figure 3b. Alternate Soil Behavior Type Charts (SBT Bqn): Qt-Bq
Figure 3c. Alternate Soil Behavior Type Charts: Q(1-Bq) - Fr
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 5 | 19
Figure 4. Normalized Soil Behavior Type Chart using Q tn (SBT Qtn)
Figure 5. Non-normalized Soil Behavior Type Chart (2010)
Zone Normalized Soil Behavior Type
1 2
3 4
5 6
7 8
9 sensitive fine grained
organic material
clay to silty clay
clayey silt to silty clay
silty sand to sandy silt
clean sands to silty sands
gravelly sand to sand
very stiff sand to clayey sand
very stiff fine grained
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 6 | 19
Figure 6. Modified SBTn Behavior Based Chart
Details regarding the geotechnical parameter calculations are provided in Table s 1a and 1b . The appropriate references cited are listed in Table 2. Non-liquefaction specific parameters are detailed in Table 1a and liquefaction specific parameters are detailed in Table 1b.
Where methods are based on charts or techniques that are too complex to describe in this summary, we recommend that the user refer to the cited material. Specific limitations for each method are described in the cited material.
Where the results of a calculation/correlation are deemed ‘invalid’ the value will be represented by the text strings “-9999”, “-9999.0”, the value 0.0 (Zero) or an empty cell . Invalid results will occur b ecause of (and not limited to) one or a combination of:
1. Invalid or undefined CPT data (e.g., drilled out section or data gap).
2. Where the calculation method is inappropriate, for example, drained parameters in a material behaving in an undrained manner (and vice versa).
3. Where input values are beyond the range of the referenced charts or specified limitations of the correlation method.
4. Where pre-requisite or intermediate parameter calculations are invalid.
The parameters selected for output from the program are often specific to a particular project. As such, not all of the calculated parameters listed in Tables 1and 1a may be included in the output files delivered with this report.
The output files are typically provided in Microsoft Excel XLS, XLSX or CSV format. The ConeTec software has several options for output depending on the number or types of calculated parameters desired or those speci fically contracted for by the client. Each output file is named using the original file base name (from the .COR file) followed
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 7 | 19
by a three or four character indicator of the output set selected (e.g. BSC, TBL, NLI , NL2, IFI, IFI2, IFI3) and possibly followed by an operator selected suffix identifying the characteristics of the particular calculation run.
Table 1a. CPT Parameter Calculation Methods – Non liquefaction Parameters Reference Notes: CK* - Common Knowledge, U* - Unpublished
Calculated
Parameter Description Equation Ref
Depth
Mid Layer Depth
(where calculations are done at each point then Mid Layer Depth = Recorded Depth)
[Depth (Layer Top) + Depth (Layer Bottom)]/ 2.0 CK*
Elevation
Elevation of Mid Layer is based on the sounding collar elevation supplied by the client or through a site survey
In Sweden a variation of elevation is used where the elevation increases with depth. We refer to this as inverse elevation.
Elevation = Collar Elevation – Depth
InverseElevation = Collar Elevation + Depth
CK*
N/A
Avg qc Averaged recorded tip value (qc)
=
=
n
i
cqnAvgqc
1 1
n=1 when calculations are done at each point
CK*
Avg qt
Averaged corrected tip (qt) where:
𝑞𝑡 = 𝑞𝑐 + (1 − 𝑎) ∙ 𝑢2
Averaged qt is not calculated using the average qc and averaged u values. Averaged qt is based on the average of the qt values calculated at each data point.
=
=
n
i
tqnAvgqt
1 1
n=1 when calculations are done at each point
1 Avg fs
Averaged sleeve friction (fs)
No pore pressure corrections are applied to fs.
=
=
n
i
fsnAvgfs
1 1
n=1 when calculations are done at each point
CK*
Avg Rf
Averaged friction ratio (Rf) where friction ratio is defined as:
𝑅𝑓 = 100% ∙
𝑓𝑠
𝑞𝑡
Avgqt
AvgfsAvgRf = %100
not an average of individual Rf values
CK*
Avg u Averaged dynamic pore pressure (u)
=
=
n
i
iunAvgu
1 1
n=1 when calculations are done at each point
CK*
Avg Res Averaged Resistivity (this data is not always available since it is a specialized test requiring an additional module)
=
=
n
i iyResistivitnsAvgR
1 1e
n=1 when calculations are done at each point
CK*
Avg UVIF
Averaged UVIF ultra-violet induced fluorescence (this data is not always available since it is a specialized test requiring an additional module)
=
=
n
i
iUVIFnAvgUVIF
1 1
n=1 when calculations are done at each point
CK*
Avg Temp Averaged Temperature (this data is not always available)
=
=
n
i ieTemperaturnAvgTemp
1 1
n=1 when calculations are done at each point
CK*
Avg Gamma Averaged Gamma Counts (this data is not always available since it is a specialized test requiring an additional module)
=
=
n
i
iGammanAvgGamma
1 1
n=1 when calculations are done at each point
CK*
SBT Soil Behavior Type as defined by Robertson et al 1986 (often referred to as Robertson and Campanella, 1986) See Figure 1 1, 5 SBTn Normalized Soil Behavior Type as defined by Robertson 1990 (linear normalization using Qt, now referred to as Qt1) See Figure 2 2, 5 Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 8 | 19
Calculated
Parameter Description Equation Ref
SBT-Bq Non-normalized Soil Behavior type based on non-normalized tip resistance and the Bq parameter See Figure 3a 1, 2, 5
SBT-Bqn Normalized Soil Behavior type based on normalized tip resistance (Qt, now called Qt1) and the Bq parameter See Figure 3b 2, 5 SBT-JandD Soil Behavior Type as defined by Jeffries and Davies See Figure 3c 7 SBT Qtn
Soil Behavior Type as defined by Robertson (2009) using a variable stress ratio exponent for normalization based on Ic (PKR 2009)
See Figure 4 15
Modified Non-
normalized SBT
Chart
SBT (PKR2010)
This is a revised version of the simple 1986 non-normalized SBT chart (presented at CPT ’10). The revised version has been reduced from 12 zones to 9 zones to be similar to the
normalized Robertson charts. Other updates include a
dimensionless tip resistance normalized to atmospheric
pressure, qt/Pa, on the vertical axis and a log scale for non- normalized friction ratio, Rf, along the horizontal axis.
See Figure 5 33
Modified SBTn
(contractive
/dilative)
Modified SBTn chart as defined by Robertson (2016) indicating zones of contractive/dilative behavior. Note that ConeTec displays the chart with colors different from Robertson.
ConeTec’s colors were chosen to avoid confusion with soil type descriptions.
See Figure 6 30
Unit Wt.
Unit Weight of soil determined from one of the following user selectable options:
1) uniform value
2) value assigned to each SBT zone
3) value assigned to each SBTn zone
4) value assigned to SBTn zone as determined from Robertson and Wride (1998) based on qc1n
5) values assigned to SBT Qtn zones
6) values based on Robertson updated non-normalized Soil Behavior Type Chart (2010b)
6) Mayne fs (sleeve friction) method
7) Robertson and Cabal 2010 method
8) user supplied unit weight profile
The last option may co-exist with any of the other options.
See references
3, 5, 15,
21, 24,
29, 33
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 9 | 19
Calculated
Parameter Description Equation Ref
TStress
v
Total vertical overburden stress at Mid Layer Depth
A layer is defined as the averaging interval specified by the user where depths are reported at their respective mid-layer depth.
For data calculated at each point layers are defined using the recorded depth as the mid-point of the layer. Thus, a layer starts half-way between the previous depth and the current depth unless this is the first point in which case the layer start is at zero depth. The layer bottom is half-way from the current depth to the next depth unless it is the last data point.
Defining layers affects how stresses are calculated since the unit weight attributed to a data point is used throughout the entire layer. This means that to calculate the stresses the total stress at the top and bottom of a layer are required. The stress at mid layer is determined by adding the incremental stress from the layer top to the mid-layer depth. The stress at the layer bottom becomes the stress at the top of the subsequent layer. Stresses are NOT calculated from mid-point to mid-point.
For over-water work the total stress due to the column of water above the mud line is taken into account where appropriate.
hi
n
i i
TStress
=
=
1
where I is layer unit weight
hi is layer thickness
CK*
EStress
v’
Effective vertical overburden stress at mid-layer depth. v’ = v - ueq CK* Equil u
ueq or u0
Equilibrium pore pressures are determined from one of the following user selectable options:
1) hydrostatic below the water table
2) user supplied profile
3) combination of those above
When a user supplied profile is used/provided a linear
interpolation is performed between equilibrium pore pressures defined at specific depths. If the profile values start below the water table then a linear transition from zero pressure at the water table to the first defined pointed is used.
Equilibrium pore pressures may come from dissipation tests, adjacent piezometers or other sources. Occasionally, an extra equilibrium point (“assumed value”) will be provided in the profile that does not come from a recorded value to smooth out any abrupt changes or to deal with material interfaces. These “assumed” values will be indicated on our plots and in tabular summaries.
For the hydrostatic option:
( )wtweq DDu −=
where ueq is equilibrium pore pressure
w is the unit weight of water
D is the current depth
Dwt is the depth to the water table
CK*
K0 Coefficient of earth pressure at rest, K0. Ko = (1 – sinΦ’) OCR sinΦ’ 17 Cn Overburden stress correction factor
used for (N1)60 and older CPT parameters.
Cn = (Pa/v’)0.5
where 0.0 < Cn < 2.0 (user adjustable, typically
ranging from 1.7 to 2.0)
Pa is atmospheric pressure (100 kPa)
4, 12
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 10 | 19
Calculated
Parameter Description Equation Ref
Cq Overburden stress normalizing factor.
Cq = 1.8 / [0.8 + (v’/Pa)]
where 0.0 < Cq < 2.0 (user adjustable)
Pa is atmospheric pressure (100 kPa)
Robertson and Wride define Cq to be the same as
Cn. The Olson definition above is used in the
program.
3, 12
N60
SPT N value at 60% energy calculated from qt/N ratios assigned to each SBT zone. This method has abrupt N value changes at zone boundaries.
See Figure 1 5
(N1)60 SPT N60 value corrected for overburden pressure. (N1)60 = Cn • N60 4 N60Ic
SPT N60 values based on the Ic parameter, as defined by Robertson and Wride 1998 (3), or by Robertson 2009 (15).
(qt/Pa)/ N60 = 8.5 (1 – Ic/4.6)
(qt/Pa)/ N60 = 10 (1.1268 – 0.2817Ic)
Pa being atmospheric pressure
3, 5
15, 31
(N1)60Ic SPT N60 value corrected for overburden pressure (using N60 Ic).
User has 3 options.
1) (N1)60Ic= Cn • (N60 Ic)
2) qc1n/ (N1)60Ic = 8.5 (1 – Ic/4.6)
3) (Qtn)/ (N1)60Ic = 10 (1.1268 – 0.2817Ic)
4 5
15, 31
Su
or Su (Nkt)
Undrained shear strength based on qt
Su factor Nkt is user selectable.
N
qtSu
kt
v−=
1, 5
Su
or Su (Ndu)
or Su (NΔu)
Undrained shear strength based on pore pressure
Su factor NΔu is user selectable.
N
uuSu
u
eq
−=
2 1, 5
Dr
Relative Density determined from one of the following user selectable options:
1) Ticino Sand
2) Hokksund Sand
3) Schmertmann (1978)
4) Jamiolkowski (1985) - All Sands
5) Jamiolkowski et al (2003) (various compressibilities, Ko)
See reference (methods 1 through 4)
Jamiolkowski et al (2003) reference
5 14
PHI
Friction Angle determined from one of the following user selectable options (methods 1 through 4 are for sands and method 5 is for silts and clays):
1) Campanella and Robertson
2) Durgunoglu and Mitchel
3) Janbu
4) Kulhawy and Mayne
5) NTH method (clays and silts)
See appropriate reference
5 5
5 11
23 Delta U/qt
Δu/qt
du/qt
Differential pore pressure ratio
(older parameter used before Bq was established)
qt
u=
where:
equuu −=
and u = dynamic pore pressure
ueq = equilibrium pore pressure
39 Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 11 | 19
Calculated
Parameter Description Equation Ref
Bq Pore pressure parameter
vqt
uBq −
=
equuu −= :where
and u = dynamic pore pressure
ueq = equilibrium pore pressure
1, 2, 5
Net qt
or qtNet
Net tip resistance
(used in many subsequent correlations)
vqt−
36 qe or qE or qE
Effective tip resistance
(using the dynamic pore pressure u2 and not equilibrium pore pressure)
𝑞𝑡 − 𝑢2 36
qeNorm Normalized effective tip resistance
'
2 v
uqt−
36 Qt
or Norm: Qt
or Qt1
Normalized qt for Soil Behavior Type classification as defined by Robertson (1990) using a linear stress normalization. Note this is different from Qtn. This parameter was renamed to Qt1 in Robertson, 2009. Without normalization limits this parameter calculates to very high unrealistic values at low stresses.
'
v
vqtQt −=
2, 5,
15 Fr
or Norm: Fr
Normalized Friction Ratio for Soil Behavior Type classification as defined by Robertson (1990)
vqt
fsFr −= %100
2, 5
Q(1-Bq)
Q(1-Bq) + 1
Q(1-Bq) grouping as suggested by Jefferies and Davies for their classification chart and the establishment of their Ic parameter.
Later papers added the +1 term to the equation.
𝑄 ⋅ (1 − 𝐵𝑞)
𝑄 ⋅ (1 − 𝐵𝑞) + 1
where Bq is defined as above and Q is the same as
the normalized tip resistance, Qt1, defined above
6, 7,
34 qc1 Normalized tip resistance, qc1, using a fixed stress ratio exponent, n (this method has stress units)
qc1 = qt • (Pa/v’)0.5
where: Pa = atmospheric pressure
21 qc1 (0.5) Normalized tip resistance, qc1, using a fixed stress ratio exponent, n (this method is unit-less)
qc1 (0.5)= (qt/Pa) • (Pa/v’)0.5
where: Pa = atmospheric pressure
5 qc1 (Cn) Normalized tip resistance, qc1, based on Cn
(this method has stress units) qc1(Cn) = Cn * qt 5, 12 qc1 (Cq) Normalized tip resistance, qc1, based on Cq
(this method has stress units) qc1 (Cq)= Cq * qt (some papers use qc) 5, 12 qc1n
normalized tip resistance, qc1n, using a variable stress ratio exponent, n (where n=0.0, 0.70, or 1.0)
(this method is unit-less)
qc1n = (qt / Pa)(Pa/v’)n
where: Pa = atm. Pressure and n varies as
described below
3 Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 12 | 19
Calculated
Parameter Description Equation Ref
Ic
or
Ic (RW1998)
Soil Behavior Type Index as defined by Robertson and Wride (1997, 1998) for estimating grain size characteristics and providing smooth gradational changes across the SBTn chart.
Ic(RW1998) is different from that of Jefferies and Davies (7) and is different from Ic(PKR2009).
Ic = [(3.47 – log10Q)2 + (log10 Fr + 1.22)2 ]0.5
Where:
n
v
a
a
v P
P
qtQ
−= '
Or
n
v
a
a
nc
P
P
qtqQ
== '1
depending on the iteration in determining Ic
And Fr is in percent
Pa = atmospheric pressure
n has the following distinct values:
0.5, 0.75 and 1.0
and is determined in an iterative manner based on
the resulting Ic in each iteration
Note that NCEER replaced 0.75 with 0.70
3, 4, 5
10 Ic (PKR 2009)
Soil Behavior Type Index, Ic (PKR 2009) is based on a variable stress ratio exponent n, which itself is based on Ic (PKR 2009).
An iterative calculation is required to determine Ic (PKR 2009) and its corresponding n (PKR 2009).
Ic (PKR 2009) =
[(3.47 – log10Qtn)2 + (1.22 + log10Fr)2]0.5 15
n (PKR 2009)
Stress ratio exponent n, based on Ic (PKR 2009).
An iterative calculation is required to determine n (PKR 2009) and its corresponding Ic (PKR 2009).
n (PKR 2009) = 0.381 (Ic) + 0.05 (v’/Pa) – 0.15 15
Qtn (PKR 2009)
Normalized tip resistance using a variable stress ratio exponent based on Ic (PKR 2009) and n (PKR 2009). An iterative
calculation is required to determine Qtn (PKR 2009).
Qtn = [(qt - v)/Pa](Pa/v’)n
where Pa = atmospheric pressure (100 kPa)
n = stress ratio exponent described above
15 FC Apparent fines content (%)
FC=1.75(Ic3.25) - 3.7
FC=100 for Ic > 3.5
FC=0 for Ic < 1.26
FC = 5% if 1.64 < Ic < 2.6 AND Fr<0.5
3 Ic Zone
This parameter is the Soil Behavior Type zone based on the Ic parameter (valid for zones 2 through 7 on SBTn or SBT Qtn charts)
Ic < 1.31 Zone = 7
1.31 < Ic < 2.05 Zone = 6
2.05 < Ic < 2.60 Zone = 5
2.60 < Ic < 2.95 Zone = 4
2.95 < Ic < 3.60 Zone = 3
Ic > 3.60 Zone = 2
3 CD
The contractive / dilative boundary on Robertson’s Modified SBTn (contractive/dilative) Chart shown in Figure 6 above. The boundary is marked as CD = 70 on the chart in the relevant paper. Similar to the Qtn,cs = 70 line in Figure 4.
CD = 70 = (Qtn – 11) ( 1 + 0.06Fr)17
lower bound of CD = 60:
CD = 60 = (Qtn – 9.5) ( 1 + 0.06Fr)17
30 Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 13 | 19
Calculated
Parameter Description Equation Ref
IB
Hyberbolic fit defining the boundary between SBT soil types proposed by Schneider as a better fit than the Ic circles. IB = 32 represents the boundary for most sand like soils. IB = 22 represents the upper boundary for most clay like soils. The region between IB=22 and IB=32 is the “transitional soil” zone.
IB = 100 (Qtn + 10) / (70 + Qtn Fr) 30
State Param
or State
Parameter
or ψ
The state parameter index, ψ, is defined as the difference between the current void ratio, e, and the critical void ratio, ec.
Positive ψ - contractive soil
Negative ψ - dilative soil
This is based on the work by Been and Jefferies (1985) and Plewes, Davies and Jefferies (1992)
This method uses mean normal stresses based on a uniform value of K0 or a calculated K0 using methods described
elsewhere in this document
See reference 6, 8
Yield Stress
σp’
Yield stress is calculated using the following methods
1) General method
2) 1st order approximation using qtNet (clays)
3) 1st order approximation using Δu2 (clays)
4) 1st order approximation using qe (clays)
5) Based on Vs
All stresses in kPa
1) σp’= 0.33·(qt – σv)m’ (σatm/100)1-m’
where
25)65.2/(1
28.01'
cIm +−=
2) σp’ = 0.33·(qt – σv)
3) σp’ = 0.54· (Δu2) Δu2 = u2 – u0
4) σp’ = 0.60 · (qt – u2)
5) σp’ = (Vs/4.59)1.47
19 20
20 20
18 OCR
OCR(JS1978)
YSR(Mayne2014)
YSR (qtNet)
YSR (deltaU)
YSR (qe)
YSR (Vs)
OCR (PKR2015)
Over Consolidation Ratio based on
1) Schmertmann (1978) method involving a plot
plot of Su/v’ /( Su/v’)NC and OCR
2) based on Yield stresses described above
3) approximate version based on qtNet
4) approximate version based on Δu
5) approximate version based on effective tip, qe
6) approximate version based on shear wave velocity, Vs and v’ 7) based on Qt
1) requires a user defined value for NC Su/Pc’ ratio
2 through 5) based on yield stresses
6) YSR (Vs) = σp’(Vs) / v’
7) OCR = 0.25·(Qt)1.25
9 19
20 20
20 18
32 Es/qt
Intermediate parameter for calculating Young’s Modulus, E, in sands. It is the Y axis of the reference chart.
Note that Figured 5.59 from reference 5, Lunne, Robertson and Powell, (LRP) has an error. The X axis values are too high by a factor of 10. The plot is based on Baldi's (not Bellotti as cited in Based on Figure 5.59 in the reference 5, 37
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 14 | 19
Calculated
Parameter Description Equation Ref
LRP) original Figure 3 where the X axis is:
𝑞𝑐
√𝜎𝑣′
(both in kPa) with a range of 200 to 3000.
Figure 5.59 from LRP shows a dimensionless form of the
equation, qc1, displaying the same range of values.
Figure 5.59’s X axis uses 𝑞𝑐1 = (
𝑞𝑐
𝑃𝑎
) (
𝑃𝑎
𝜎𝑣′)
0.5 The two expressions are not the same: they differ by a factor of
√𝑃𝑎
𝑃𝑎
. With Pa taken to be 100 kPa the factor is 1/10.
Substituting typical values of 200 bar (20000 kPa) for qc and 225 kPa for σv’ one gets: 20000 / 15 = 1333.33 for Bellotti’s axis and (200/1)(100/225)0.5 = 200 * (10/15) = 133.3 for LRP’s axis (noting that Pa = 1 bar) showing a factor of 10 difference.
Es or Es
Young’s
Modulus E
Young’s Modulus based on the work done in Italy. There are three types of sands considered in this technique. The user selects the appropriate type for the site from:
a) OC Sands
b) Aged NC Sands
c) Recent NC Sands
Each sand type has a family of curves that depend on mean normal stress. The program calculates mean normal stress and linearly interpolates between the two extremes provided in the Es/qt chart. Es is evaluated for an axial strain of 0.1%.
Mean normal stress is evaluated from:
𝜎𝑚
′ = 1
3 (𝜎𝑣
′ + 𝜎ℎ
′ + 𝜎ℎ
′ )
where v’= vertical effective stress
h’= horizontal effective stress
and h = Ko ٠ v’ with Ko assumed to be 0.5
5 Delta U/TStress
Δu / σv
Differential pore pressure ratio with respect to total stress v
u
= where:
equuu −= 39
Delta U/EStress,
P Value,
Excess Pore
Pressure Ratio
Δu/σv’
Differential pore pressure ratio with respect to effective stress.
Key parameter (P, Normalized Pore Pressure Parameter, Excess Pore Pressure Ratio) in the Winckler et. al. static liquefaction method.
'
v
u
=
where:
equuu −=
25, 25a
Su/EStress
Su/σv’
Undrained shear strength ratio with respect to vertical effective overburden stress using the Su (Nkt) method
= Su (Nkt) / v’
9, 23
Vs or Vs
Recorded shear wave velocities (not estimated).
The shear wave velocities are typically collected over 1 m depth intervals. Each data point over the relevant depth range is assigned the same Vs value.
recorded data 27
Vp or Vp
Recorded compression wave (or P wave) velocities (not
estimated). The P wave velocities are typically collected over 1 m depth intervals. Each data point over the relevant depth range is assigned the same Vp value.
recorded data 27
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 15 | 19
Calculated
Parameter Description Equation Ref
Vs30
Vs100
The average shear wave velocity of the near surface materials to a depth of 30 m (100 ft). It is based on the sum of all travel times through all layers in the top 30m (100 ft).
Vs100 is the same calculation as Vs30 except down to a depth of 100 feet.
𝑉𝑠30 = 𝑡𝑜𝑡𝑎𝑙 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 𝑜𝑓 𝑎𝑙𝑙 𝑙𝑎𝑦𝑒𝑟𝑠 𝑡𝑜 30 𝑚
Σ ( 𝑙𝑎𝑦𝑒𝑟 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠
𝑙𝑎𝑦𝑒𝑟 𝑠ℎ𝑒𝑎𝑟 𝑤𝑎𝑣𝑒 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦)
𝑉𝑠30 = 𝑡𝑜𝑡𝑎𝑙 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 𝑜𝑓 𝑎𝑙𝑙 𝑙𝑎𝑦𝑒𝑟𝑠 𝑡𝑜 30 𝑚
Σ (𝑙𝑎𝑦𝑒𝑟 𝑡𝑟𝑎𝑣𝑒𝑙 𝑡𝑖𝑚𝑒𝑠)
38 Gmax
Gmax determined from SCPT shear wave velocities (not
estimated values). Note that seismic data (Vs) is collected over set depth intervals (typically 1 meter). Each data point over the test segment is assigned the same Vs value. Since soil density changes with depth, slightly different Gmax values may be calculated over the test depth interval.
Gmax = ρVs2
where ρ is the mass density of the soil determined
from the estimated unit weights at each test depth
27 qtNet/Gmax
Net tip resistance ratio with respect to the small strain modulus Gmax determined from SCPT shear wave velocities (not
estimated values)
= (qt - v) / Gmax
where Gmax = ρVs2
and ρ is the mass density of the soil determined
from the estimated unit weights at each test depth
15, 28,
30 qUlt
A site specific and client specific parameter for estimating the limiting stress for “crane walk” accessibility
𝑞𝑢𝑙𝑡 = 𝐶𝑟𝑎𝑛𝑒𝑊𝑎𝑙𝑘𝐹𝑎𝑐𝑡𝑜𝑟 ∙ 𝑆𝑢
Where: CraneWalkFactor is client provided
U*
Estimated Go
Estimated value for small strain shear modulus
Go = 0.0188[10(0.55Ic + 1,68)](qt - σv) 15
Estimated E25
Estimated value for Young’s Modulus, E, at a 25% working load
E25 = αE (qtNet)
where αE = 0.015[10(0.55Ic + 1,68)]
15 kSBT
Estimated soil permeability derived from Soil Behavior Type (SBT) Chart Ic values.
For 1.0 < Ic ≤ 3.27:
k = 10(0.952 – 3.04Ic) in m/s
For 3.27 < Ic < 4.0:
k = 10(-4.52 – 1.37Ic) in m/s
35 M or D’
Constrained
Modulus
Constrained Modulus based on
1) Robertson, M
2) Mayne, D’
1) Robertson
M = αM (qt - σv)
Ic > 2.2 (fine grained)
αM = Qt when Qt < 14
αM = 14 when Qt > 14
Ic < 2.2 (coarse grained)
αM = 0.0188 [10(0.55Ic + 1.68))
D’ = αD (qt - σv)
where αD = 5
32 23
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 16 | 19
Table 1b. CPT Parameter Calculation Methods – Liquefaction Parameters
Calculated
Parameter Description Equation Ref
KSPT or Ks Equivalent clean sand factor for (N1)60 KSPT = 1 + ((0.75/30) • (FC – 5)) 10 KCPT
or
Kc (RW1998)
Equivalent clean sand correction for qc1N
Kcpt = 1.0 for Ic 1.64
Kcpt = f(Ic) for Ic > 1.64 (see reference)
Kc = – 0.403 Ic4 + 5.581 Ic3 – 21.63Ic2 + 33.75 Ic – 17.88
3, 10
Kc (PKR 2010) Clean sand equivalent factor to be applied to Qtn Kc = 1.0 for Ic ≤ 1.64
Kc = – 0.403 Ic4 + 5.581 Ic3 – 21.63Ic2 + 33.75 Ic – 17.88 for Ic > 1.64
16 (N1)60csIc Clean sand equivalent SPT (N1)60Ic. User has 3 options.
1) (N1)60csIc = α + β((N1)60Ic)
2) (N1)60csIc = KSPT * ((N1)60Ic)
3) (qc1ncs)/ (N1)60csIc = 8.5 (1 – Ic/4.6)
FC ≤ 5%: α = 0, β=1.0
FC ≥ 35% α = 5.0, β=1.2
5% < FC < 35% α = exp[1.76 – (190/FC2)]
β = [0.99 + (FC1.5/1000)]
10 10
5 qc1ncs Clean sand equivalent qc1n qc1ncs = qc1n • Kcpt 3 Qtn,cs (PKR
2010)
Clean sand equivalent for Qtn described above
- Qtn being the normalized tip resistance based on a variable stress exponent as defined by Robertson (2009)
Qtn,cs = Qtn · Kc (PKR 2016) 16
Su(Liq)/ESv
or
Su(Liq)/σv’
Liquefied shear strength ratio as defined by Olson and Stark
Su(Liq) = 0.03 + 0.0143(qc1)
v’
Note: v’ and sv’ are synonymous
13 Su(Liq)/ESv
or
Su(Liq)/σv’
(PKR 2010)
Liquefied shear strength ratio as defined by Robertson (2010)
Su(Liq)
v’
Based on a function involving Qtn,cs
16 Su (Liq)
(PKR 2010)
Liquefied shear strength derived from the liquefied shear strength ratio and effective overburden stress 𝑆𝑢(𝐿𝑖𝑞) = 𝜎𝑣 ′ ∙ (𝑆𝑢(𝐿𝑖𝑞)
𝜎𝑣′ ) 16
Cont/Dilat Tip Contractive / Dilative qc1 Boundary based on (N1)60 (v’)boundary = 9.58 x 10-4 [(N1)60]4.79 qc1 is calculated from specified qt(MPa)/N ratio
13 CRR Cyclic Resistance Ratio (for Magnitude 7.5)
qc1ncs < 50:
CRR7.5 = 0.833 [qc1ncs/1000] + 0.05
50 qc1ncs < 160:
CRR7.5 = 93 [qc1ncs/1000]3 + 0.08
10 Kg or Kg Small strain Stiffness Ratio Factor, Kg [Gmax/qt]/[qc1n-m] m = empirical exponent, typically 0.75 26
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 17 | 19
Calculated
Parameter Description Equation Ref
Kg* Revised Kg factor extended to fine grained soils (Robertson). Kg* = (Go / qn)(Qtn)0.75 where qn is the net tip resistance = qt -σv 30
SP Distance State Parameter Distance, Winckler static liquefaction method Perpendicular distance on Qtn chart from plotted point to state parameter Ψ = -0.05 curve 25
URS NP Fr Normalized friction ratio point on Ψ = -0.05 curve used in SP distance calculation 25
URS NP Qtn Normalized tip resistance (Qtn) point on Ψ = -0.05 curve used in SP Distance calculation 25
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 18 | 19
Table 2. References
No. Reference
1 Robertson, P.K., Campanella, R.G., Gillespie, D. and Greig, J., 1986, “Use of Piezometer Cone Data”, Proceedings of InSitu 86, ASCE Specialty Conference, Blacksburg, Virginia. 2 Robertson, P.K., 1990, “Soil Classification Using the Cone Penetration Test”, Canadian Geotechnical Journal, Volume 27. This includes the discussions and replies.
3 Robertson, P.K. and Wride (Fear), C.E., 1998, “Evaluating cyclic liquefaction potential using the cone penetration test”, Canadian Geotechnical Journal, 35: 442-459. 4 Robertson, P.K. and Wride, C.E., 1997, “Cyclic Liquefaction and its Evaluation Based on SPT and CPT”, NCEER Workshop Paper, January 22, 1997.
5 Lunne, T., Robertson, P.K. and Powell, J. J. M., 1997, “ Cone Penetration Testing in Geotechnical Practice,” Blackie Academic and Professional.
6 Plewes, H.D., Davies, M.P. and Jefferies, M.G., 1992, “CPT Based Screening Procedure for Evaluating Liquefaction Susceptibility”, 45th Canadian Geotechnical Conference, Toronto, Ontario, October 1992.
7 Jefferies, M.G. and Davies, M.P., 1993, “Use of CPTu to Estimate equivalent N60”, Geotechnical Testing Journal, 16(4): 458-467.
8 Been, K. and Jefferies, M.P., 1985, “A state parameter for sands”, Geotechnique, 35(2), 99-112. 9 Schmertmann, 1978, “Guidelines for Cone Penetration Test Performance and Design”, Federal Highway Administration Report FHWA-TS-78-209, U.S. Department of Transportation. 10 Proceedings of the NCEER Workshop on Evaluation of Liquefaction Resistance of Soils, Salt Lake City, 1996, chaired by Leslie Youd.
11 Kulhawy, F.H. and Mayne, P.W., 1990, “Manual on Estimating Soil Properties for Foundation Design, Report No. EL-6800”, Electric Power Research Institute, Palo Alto, CA, August 1990, 306 p. 12 Olson, S.M. and Stark, T.D., 2002, “Liquefied strength ratio from liquefied flow failure case histories”, Canadian Geotechnical Journal, 39: 951-966.
13 Olson, Scott M. and Stark, Timothy D., 2003, “Yield Strength Ratio and Liquefaction Analysis of Slopes and Embankments”, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, August 2003. 14 Jamiolkowski, M.B., Lo Presti, D.C.F. and Manassero, M., 2003, “Evaluation of Relative Density and Shear Strength of Sands from CPT and DMT”, Soil Behaviour and Soft Ground Construction, ASCE, GSP N0. 119, 201-238.
15 Robertson, P.K., 2009, “Interpretation of cone penetration tests – a unified approach”, Canadian Geotechnical Journal, 46: 1337-1355.
16 Robertson, P.K., 2010a, “Evaluation of Flow Liquefaction and Liquefied Strength Using the Cone Penetration Test”, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, June 2010. 17 Mayne, P.W. and Kulhawy, F.H., 1982, "Ko-OCR Relationships in Soil", Journal of the Geotechnical Engineering Division, ASCE, Vol. 108, GT6, pp. 851-872.
18 Mayne, P.W., Robertson P.K. and Lunne T., 1998, “Clay stress history evaluated from seismic piezocone tests”, Proceedings of the First International Conference on Site Characterization – ISC ’98, Atlanta Georgia, Volume 2, 1113-1118.
Calculated CPT Geotechnical Parameters – Revision SZW-Rev 18 Page 19 | 19
No. Reference
19 Mayne, P.W., 2014, “Generalized CPT Method for Evaluating Yield Stress in Soils”, Geocharacterization for Modeling and Sustainability (GSP 235: Proc. GeoCongress 2014, Atlanta, GA), ASCE, Reston, Virginia:
1336-1346.
20 Mayne, P.W., 2015, “Geocharacterization by In-Situ Testing”, Continuing Education Course, Vancouver, BC, January 6-8, 2015.
21 Robertson, P.K. and Fear, C.E., 1995, “Liquefaction of sands and its evaluation”, Proceedings of the First International Conference on Earthquake Engineering, Keynote Lecture IS Tokyo ‘95, Tokyo Japan, 1995.
22 Mayne, P.W., Peuchen, J. and Boumeester, D., 2010, “Soil unit weight estimation from CPTs”, Proceeding of the 2nd International Symposium on Cone Penetration Testing (CPT ’10), Vol 2, Huntington Beach, California; Omnipress: 169-176.
23 Mayne, P.W., 2007, “NCHRP Synthesis 368 on Cone Penetration Test”, Transportation Research Board, National Academies Press, Washington, D.C., 118 pages.
24 Mayne, P.W., 2014, “Interpretation of geotechnical parameters from seismic piezocone tests.”, Key note address #2, proceedings, 3rd International Symposium on Cone Penetration Testing (CPT’14, Las Vegas), ISSMGE Technical Committee TC102.
25 Winckler, Christina, Davidson, Richard, Yenne, Lisa, Pilz, Jorgen, 2014, “CPTu-Based State Characterization of Tailings Liquefaction Susceptibility”, Tailings and Mine Waste, 2014. 25a Winckler, Christina, Davidson, Richard, Yenne, Lisa, Pilz, Jorgen, 2014, “CPTu-Based State Characterization of Tailings Liquefaction Susceptibility”, Powerpoint presentation, Tailings and Mine Waste, 2014. 26 Schneider, J.A. and Moss, R.E.S., 2011, “Linking cyclic stress and cyclic strain based methods for assessment of cyclic liquefaction triggering in sands”, Geotechnique Letters 1, 31-36. 27 Rice, A., 1984, “The Seismic Cone Penetrometer”, M.A.Sc. thesis submitted to the University of British Columbia, Dept. of Civil Engineering, Vancouver, BC, Canada. 28 Gillespie, D.G., 1990, “Evaluating Shear Wave Velocity and Pore Pressure Data from the Seismic Cone Penetration Test”, Ph.D. thesis submitted to the University of British Columbia, Dept. of Civil Engineering, Vancouver, BC, Canada.
29 Robertson, P.K and Cabal, K.L., 2010, “Estimating soil unit weight from CPT”, Proceedings of the 2nd International Symposium on Cone Penetration Testing (CPT ’10), Huntington Beach, California. 30 Robertson, P.K., 2016, “Cone penetration test (CPT)-based soil behaviour type (SBT) classification system – an update”, Canadian Geotechnical Journal, July 2016.
31 Robertson, P.K., 2012, “Interpretation of in-situ tests – some insights”, Mitchell Lecture, ISC’4, Recife, Brazil. 32 Robertson, P.K., Cabal, K.L. 2015, “Guide to Cone Penetration Testing for Geotechnical Engineering”, 6th Edition.
33 Robertson, P.K., 2010b, “Soil behaviour type from CPT: an update”, Proceedings of the 2nd International Symposium on Cone Penetration Testing (CPT ’10), Huntington Beach, California. 34 Been, K., Romero, S., Obermeyer, J. and Hebeler, G., 2012, “Determining in situ state of sand and silt tailings from the CPT”, Tailings and Mine Waster 2012, 325-333.
35 Robertson, P.K., 2010, “Estimating in-situ soil permeability from CPT & CPTu”, Proceedings of the 2nd International Symposium on Cone Penetration Testing (CPT ’10), Huntington Beach, California. 36 Mayne, P.W., Cargill, E. and Greig, J., 2023, “The Cone Penetration Test: A CPT Design Parameter Manual”, ConeTec Group
37 Baldi, G., Bellotti, R., Ghionna,V., Jamiolkowski, M. and Lo Presti, D. 1989. Modulus of sands from CPTs and DMTs. Proc. Intl. Conf. on Soil Mechanics & Foundation Engineering, Vol. 1 (ICSMFE, Rio de Janeiro), Balkema, Rotterdam: 165–170. www.issmge.org
38 Crow, H.L, Hunter, J.A. and Bobrowsky, P.T., 2012, “National shear wave measurement guidelines for Canadian seismic site assessment”, Proceedings of GeoManitoba 2012, the 65th Canadian Geotechnical Conference.
39 Campanella, R.G., Robertson, P.K., Gillespie, D., 1982, “Cone penetration testing in deltaic soils”, Canadian Geotechnical Journal, 20: 23-35.
Calibration Records
Adara Systems Ltd.
201-8327 Eastlake Drive, Burnaby, BC, Canada V5A4W2
Tel: 1-604-273-6013
Calibration Information
Cone Serial Number Model A15 T1500 F15 U35
Date
Technician Performing Signature
Calibration
Calibration Approved By Signature
Lab Condition As Found As Left
Lab Temperature N/A 23˚C
Lab Humidity N/A 27% Reason for Calibration Repair
Cone Information
Tip Stress Limit 1500 bar Tip End Area 15 cm²
Friction Stress Limit 15 bar Friction Surface Area 225 cm² Pressure Limit 35 bar RTD Location Pressure Carrier
X-Inclinometer Limit 30 degrees Geophone X and Z
Y-Inclinometer Limit 30 degrees Temperature Range -20°C to 60°C Baseline Summary: (For Reference Only)
Channel Units As Found As Left Tip -1.064
Sleeve -0.023
Pressure 1.026
X-Inclinometer -0.013
Y-Inclinometer 0.006
Temperature 23.734
Classified in accordance with ISO 22476-1:2012 Class 1
Classified in accordance with ISO 22476-1:2012 Class 2
Calibrated in general accordance with the ASTM D5778-20 and D7400-08 standards Calibrated with Adara calibration procedure EC_CPTCAL-2.2 Collective uncertainty of the measurement standards conforms to a test uncertainty ratio (TUR) of 3:1 for tip and sleeve measurement and 4:1 for pressure measurement with a confidence level k=2
CERTIFICATE OF CALIBRATION
Vishrut Khunt
Richard Chen
2024-05-08
EC1061
bar
bar
bar
degrees
degrees
˚C
-3.622
1.235
-0.350
-0.100
23.630
0.059
Adara Systems Ltd.
201-8327 Eastlake Drive, Burnaby, BC, Canada V5A4W2
Tel: 1-604-273-6013
Cone Output vs Reference Stress/Pressure Plots
y = 0.999x - 0.072
0 300
600
900
1200
1500
1800
0 300 600 900 1200 1500 1800
Tip Output (bar)
Reference Stress (bar)
Tip Output vs Reference Stress
y = 1.000x + 0.001
0 3
6 9
12 15
18 0 3 6 9 12 15 18
Sleeve Output (bar)
Reference Stress (bar)
Sleeve Output vs Reference Stress
y = 1.000x + 0.002
0 7
14 21
28 35
42 0 7 14 21 28 35 42
Pressure Output (bar)
Reference Pressure (bar)
Pressure Output vs Reference Pressure
Adara Systems Ltd.
201-8327 Eastlake Drive, Burnaby, BC, Canada V5A4W2
Tel: 1-604-273-6013
Calibration Results
Tip Calibration
As Found As Left
Max. Non Linearity 0.08% PASS Max. Non Linearity 0.10% PASS Calibration Error 0.07% PASS Calibration Error 0.19% PASS Sleeve Calibration
As Found As Left
Max. Non Linearity 0.34% PASS Max. Non Linearity 0.01% PASS Calibration Error 0.35% PASS Calibration Error 0.05% PASS Pressure Calibration
As Found As Left
Max. Non Linearity 0.03% PASS Max. Non Linearity 0.04% PASS Calibration Error 0.09% PASS Calibration Error 0.06% PASS X-Inclinometer Calibration
As Found As Left
Max. Non Linearity N/A N/A Max. Non Linearity 0.04% PASS Calibration Error N/A N/A Calibration Error -0.08% PASS Y-Inclinometer Calibration
As Found As Left
Max. Non Linearity N/A N/A Max. Non Linearity -0.33% PASS Calibration Error N/A N/A Calibration Error 0.67% PASS
Seismic Calibration
As Found As Left
Trigger Delay Error N/A N/A Trigger Delay Error 0.02% PASS Temperature Calibration
Full Scale Error 0.23% PASS
Channel Cold Room Hot Units Ref_Temp ˚C
Tip bar
Sleeve bar
Pressure bar
Temperature ˚C
Tip Temperature Coefficient 0.178 bar/˚C PASS
Sleeve Temperature Coefficient 0.002 bar/˚C PASS
Pressure Temperature Coefficient 0.000 bar/˚C PASS
1.048
43.4 2.823
0.021
1.064
43.378
22.2 -0.915
-0.022
1.063
22.037
3.3 -4.317
-0.061
3.281
Adara Systems Ltd.
201-8327 Eastlake Drive, Burnaby, BC, Canada V5A4W2
Tel: 1-604-273-6013
Testing Equipment Details
Testing Machines Model Number Serial Calibration Due
Number Number Date
Tip Load Cell Precision P-10289 100490 2025-09-18
Sleeve Load Cell Precision P-10868 100579 2025-10-01
Digital Loadcell Indicator 4215 62140 100490 2024-07-18 Fluke Reference Pressure Monitor RPM4 A10Ms 3910 100835 2024-12-12 Tektronix Function Generator AFG3021B C030955 100751 2024-10-20 Thermometer THS-222-555 D23255834 100410 2024-07-11
Thermometer THS-222-555 D23255829 100410 2024-07-11
Thermometer THS-222-555 D20345575 100565 2024-07-14
Adara Systems Ltd.
201-8327 Eastlake Drive, Burnaby, BC, Canada V5A4W2
Tel: 1-604-273-6013
Adara Error Definitions
Actual Sensitivity The slope of the best fit line through all data points starting at zero load.
Slope Error The error in the best fit line compared to the ideal linear calibration in % .
Slope Error = (Best Fit Slope - Ideal Slope) / Ideal Slope Maximum Non Linearity This value represents the maximum error (absolute value) relative to the best fit line considering each calibration point starting at loads greater than approximately 10% of FSO.
The reported errors are a percent error of FSO.
Adara's Pass/Fail criteria is 0.5% of FSO (ASTM is 0.5% of FSO at loads > 20% FSO).
Calibration Error This value represents the maximum error (absolute value) in the recorded load value as compared to the actual load value for each calibration point for loads greater than approximately 10% of FSO.
Adara's Pass/Fail criteria for the tip and sleeve is 0.5% of MO and
1.0% of MO for the pore pressure (ASTM for the tip and sleeve is
1.5% and 1.0% of MO respectively at loads greater than 20% of FSO)
Temperature Check Passing Criteria
Tip Temperature Coefficient <0.200 bar/˚C
Sleeve Temperature Coefficient <0.005 bar/˚C
Pressure Temperature Coefficient <0.0196 bar/˚C
Figure 1: Definition of Calibration Terms for Load Cell and Transducers (Adapted from [1])
Adara Systems Ltd.
201-8327 Eastlake Drive, Burnaby, BC, Canada V5A4W2
Tel: 1-604-273-6013
A1.4 Force Transducer Calibration Requirements
A1.4.1 states the following limits:
Non Linearity Tip ≤ +0.5% of FSO
Sleeve ≤ +1.0% of FSO
Calibration Error Tip ≤ +1.5% of MO at loads > 20% FSO
Sleeve ≤ +1.0% of MO at loads > 20% FSO
A1.5 Pressure Transducer Calibrations
A1.5.1 limits:
Non Linearity Pore Pressure ≤ +1.0% of FSO
Calibration Error Pore Pressure not specified
Section 5.2 states the following allowable minimum accuracy Class 1 Cone Resistance 35 kPa or 5%
Sleeve Friction 5 kPa or 10%
Pore Pressure 10 kPa or 2%
Class 2 Cone Resistance 100 kPa or 5%
Sleeve Friction 15 kPa or 15%
Pore Pressure 25 kPa or 3%
Note: ISO Compliance is based on low end calibration only.
References
[1] ASTM D5778-20. "Standard Test Method for Electronic Friction Cone and Piezocone Penetration Testing of Soils". ASTM, West Conshohocken, PA, USA.
[2] ISO 22476-1:2012. "Geotechnical investigation and testing - Field Testing - Part 1: Electrical cone and piezocone penetration test". ISO, Geneva, Switzerland.
ASTM D7400-08. "Standard Test Methods for Downhole Seismic Testing". ASTM, West Conshohocken, PA, USA.
ASTM D5778-20 Annex A Summary [1]
ISO 22476 -1:2012 Summary [2]
0+000+060+120+180+240+300+360+420+480+540+600+660+72E W0+78TREND N66°E1-T1 123 45 5a 5a6 6
35 2
WTREND N66°E1-T20+540+600+660+720+780+000+060+120+180+240+300+360+420+48E 1 23 34 56
TREND N66°E1-T30+540+600+660+720+780+840+900+961+021+081+141+200+000+060+120+180+240+300+360+420+48E 123 4 4a5 6 543 2
Expect Excellence FAULT TRENCH LOGSLINDA VISTA FAULT EVALUATIONCUPERTINO, CALIFORNIA25712.000.001AS SHO WN
7 Soil Bedding ContactTrench ProfileHigh Fines Concentration ZoneGravels and CobblesShoringZones of Higher Fines Concentration and Clay Films.Secondary Feature Related to Soil Development 1Quaternary Surface DepositsA - CLAYEY SAND with GRAVEL (SC), light yellowish brown (10YR6/4), dense, moist, fine- to medium-grained, clay is lean (~15%), gravel is subangular to subrounded and fine to coarse (~10%)ABt - CLAYEY SAND with GRAVEL (SC), light yellowish brown (10YR6/4) to reddish brown (2.5YR4/4), dense, moist, fine- to medium-grained, clay is lean (~15%), gravel is subangular tosubrounded and fine to coarse (~15%)Bt - CLAYEY SAND with GRAVEL (SC), light yellowish brown (10YR6/4) to reddish brown (2.5YR4/4), dense, moist, fine- to medium-grained, clay is lean (~20%), gravel is subangular to subroundedand medium to coarse with some cobbles (~20%)Ct- POORLY GRADED SAND with GRAVEL and CLAY (SP-SC), dark grayish brown (2.5Y3/2), dense, moist, medium- to coarse-grained sand, clay is lean (~10%), gravel is subrounded and fine tocobble size (~20 - 30%), somewhat well developed clay lenses on the gravels, zones of silty sand deposits, some zones of massive deposition, gravels are mostly Franciscan or Santa ClaraFormation rock Ct2- POORLY GRADED SAND with GRAVEL and CLAY (SP-SC), dark brown (7.5YR7/2), dense, moist, medium- to coarse-grained sand, clay is lean (~10%), gravel is subrounded and fine to cobblesize (~20 - 30%), well developed clay lenses on the gravels, zones of silty sand deposits, gravels are mostly Franciscan or Santa Clara Formation rockCt3 - POORLY GRADED SAND with GRAVEL and CLAY (SP-SC), dark brown (7.5YR7/2), dense, moist, medium- to coarse-grained sand, clay is lean (~10%), gravel is subrounded and fine to cobblesize (~15-20%), well developed clay lenses on the gravels, deposits are thin and more regular, gravels are mostly Franciscan or Santa Clara Formation rock
EXPLANATION
2344a55a6 Clay films on gravel clasts very well developedFewer gravels (~15%) and increased medium-grained sand 00SCALE IN FEET
4 4
00SCALE IN FEET
4 4
00SCALE IN FEET
6 6
APPENDIX D
SLOPE STABILITY ANALYSIS
1.0 1.0
1000.00 lbs/ft2
250.00 lbs/ft2
1.0 1.0
Phi (°)Cohesion
(psf)Strength TypeUnit Weight (lbs/
ft3)ColorMaterial
Name
28150Mohr-
Coulomb120
SC/CL
35100Mohr-
Coulomb120
SC/SP-SM
38200Mohr-
Coulomb120
GC/SC
28200Mohr-
Coulomb120
CL/ML
0.34 500 450 400 350 300
50 100 150 200 250 300 350 400
Project No.
25712.000.001 LEBL
Drawn By
Scale 1:500
Condition Seismic - Circular
Date 4/30/2025
10857 Linda Vista Drive, Cupertino, CA
Project
SLIDEINTERPRET 9.035
1.5 1.5
1000.00 lbs/ft2
250.00 lbs/ft2
1.5 1.5
Phi (°)Cohesion
(psf)Strength TypeUnit Weight (lbs/
ft3)ColorMaterial
Name
28150Mohr-
Coulomb120
SC/CL
35100Mohr-
Coulomb120
SC/SP-SM
38200Mohr-
Coulomb120
GC/SC
28200Mohr-
Coulomb120
CL/ML
500 450 400 350 300
50 100 150 200 250 300 350 400
Project No.
25712.000.001 LEBL
Drawn By
Scale 1:500
Condition Static - Circular
Date 4/30/2025
10857 Linda Vista Drive, Cupertino, CA
Project
SLIDEINTERPRET 9.035
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