HomeMy WebLinkAboutTract Map 3552 Lot 92 Soils ReportFebruary 16, 2024 Project No. 23009-10A
Mr. Dan Locke 30130 Cabrillo Avenue Temecula, CA
Subject: Preliminary Geotechnical Interpretive Report, Proposed Additions and Additional
Dwelling Unit, Assessor’s Parcel Number 922-140-015, Located at 30130 Cabrillo
Avenue, City of Temecula, Riverside County, California
First Ascent Geotechnical Engineering is pleased to present our preliminary geotechnical interpretive report for the proposed development, Assessor’s Parcel Number 922-140-015, located at 30130 Cabrillo Avenue in the City of Temecula, Riverside County, California. This work was performed in accordance with the scope of work described in our proposal, dated November 20, 2023. The purpose of this study is to evaluate the nature, distribution, engineering properties, and geologic strata underlying the site with respect to the proposed development, and then provide preliminary grading and foundation design recommendations based on the plans or information you provided First Ascent Geotechnical Engineering appreciates the opportunity to offer our consultation and advice on this project. In the event that you have any questions, please do not hesitate to contact the undersigned at your earliest convenience.
Respectfully submitted,
FIRST ASCENT GEOTECHNICAL ENGINEERING
Christopher Hogan Rangel, PG Professional Geologist Hooshang Nezafati, PhD, PE Professional Engineer President
APPROVED BY
CITY OF TEMECULA
PUBLIC WORKS
david.pina 05/06/2024
05/06/2024 05/06/2024
05/06/20
FIRST ASCENT GEOTECHNICAL ENGINEERING Page i February 16, 2024 Project No. 23009-10A
TABLE OF CONTENTS
Section Page
INTRODUCTION ....................................................................................................................................................1
SITE DESCRIPTION ...............................................................................................................................................1
PROPOSED DEVELOPMENT ............................................................................................................................1
FIELD EXPLORATION AND LABORATORY TESTING ......................................................................................3
Field Exploration ..............................................................................................................................................3
Laboratory Testing ..........................................................................................................................................3
FINDINGS ................................................................................................................................................................3
Regional Geology ..............................................................................................................................................3
Local Geology ....................................................................................................................................................4
Landslides ..........................................................................................................................................................6
CONCLUSIONS AND RECOMMENDATIONS .......................................................................................................9
General ...............................................................................................................................................................9
Earthwork ..........................................................................................................................................................9
Earthwork and Grading ..............................................................................................................................9
Clearing and Grubbing ................................................................................................................................9
Excavation Characteristics .........................................................................................................................9
Groundwater .................................................................................................................................................9
Ground Preparation ..................................................................................................................................10
Import Earth Materials .............................................................................................................................10
Cut/Fill Transitions ...................................................................................................................................11
Cut Areas ......................................................................................................................................................11
Post Grading Considerations .......................................................................................................................11
Site Drainage ...............................................................................................................................................11
Utility Trenches ..........................................................................................................................................12
SEISMIC DESIGN CONSIDERATIONS ................................................................................................................12
Ground Motions ..............................................................................................................................................12
General .............................................................................................................................................................13
Allowable Bearing Values .............................................................................................................................13
Lateral Resistance ..........................................................................................................................................13
Foundation Observations .............................................................................................................................14
Expansive Soil Considerations ....................................................................................................................14
Building Floor Slabs ...................................................................................................................................14
Corrosivity .......................................................................................................................................................15
CONCRETE FLATWORK .....................................................................................................................................16
Thickness and Joint Spacing ........................................................................................................................16
Subgrade Preparation ...................................................................................................................................16
GRADING PLAN REVIEW AND CONSTRUCTION SERVICES .........................................................................16
REPORT LIMITATIONS ......................................................................................................................................17
FIRST ASCENT GEOTECHNICAL ENGINEERING Page ii February 16, 2024 Project No. 23009-10A
Attachments: Figure 1 – Vicinity Map (Page 2) Figure 2 – Regional Geologic Map (Page 5) Figure 3 – County Fault Map (Page 7) Figure 4 – AP Fault Map (Page 8) APPENDIX A – References (Rear of Text) APPENDIX B – Exploratory Logs (Rear of Text) APPENDIX C – Laboratory Procedures and Test Results (Rear of Text) APPENDIX D – Seismicity (Rear of Text) APPENDIX F – General Earthwork and Grading Specifications (Rear of Text) Plate 1 – Geotechnical Map (Rear of Text)
FIRST ASCENT GEOTECHNICAL ENGINEERING 1 February 16, 2024 Project Number 23009-10A
INTRODUCTION First Ascent Geotechnical Engineering is pleased to present our preliminary geotechnical interpretive report for the proposed development. The purpose of this study was to evaluate the nature, distribution, engineering properties, and geologic strata underlying the site with respect to the proposed development, and then provide preliminary grading and foundation design recommendations based on the plans or information you provided. The general location of the subject property is indicated on the Vicinity Map, Figure 1. The plans you provided were used as the base map to show geologic conditions within the subject site, see Geotechnical Map, Plate 1.
SITE DESCRIPTION
The subject property is located at 30130 Cabrillo Avenue in the City of Temecula, Riverside County, California. The approximate location of the site is shown on the Vicinity Map, Figure 1. The subject property is comprised of developed parcel of land with an existing single family residence and barn. Based on our review of historic aerial images, the existing barn was constructed in 2003. Topographic relief at the subject property is relatively low with the terrain being generally gently sloping. Elevations at the site range from approximately 1040 to 1053 feet above mean sea level (msl), for a difference of about 13± feet across the entire site. Drainage within the subject property generally flows to the west. The site is currently bordered by residential development to the east and south, as well as Cajon Drive to the north and Cabrillo Avenue to the west. Most of the vegetation on the site consists of landscaping along with small to large trees throughout the subject site.
PROPOSED DEVELOPMENT The proposed development is expected to consist of additions to the existing residence and converting the existing barn into an additional dwelling unit. Conventional slab on grade and continuous footings will be used for the structural design. The plans prepared by Wine Country Consulting were utilized in our exploration and form the base for our Geotechnical Map, Plate 1 attached at the rear of the report.
Mr. Dan Locke Proposed Additions and Additional Dwelling Unit Project No. 23009-10A Date: January 2024
First Ascent Geotechnical Engineering
VICINITY MAP FIGURE 1
Site Location
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FIELD EXPLORATION AND LABORATORY TESTING
Field Exploration Subsurface exploration within the subject site was performed on December 9, 2023 for the exploratory excavations. A hand auger was utilized to excavate two (2) borings to a maximum depth of 8 feet. An underground utilities clearance was obtained from Underground Service Alert of Southern California, prior to the subsurface exploration. Earth materials encountered during exploration were classified and logged in general accordance with the Standard Practice for Description and Identification of Soils (Visual-Manual Procedure) of ASTM D 2488. Upon completion of laboratory testing, exploratory logs and sample descriptions may have been reconciled to reflect laboratory test results with regard to ASTM D 2487. Associated with the subsurface exploration was the collection of bulk (disturbed) samples and relatively undisturbed samples of earth materials for laboratory testing and analysis. The relatively undisturbed samples were obtained with a 3 inch outside diameter modified California split-spoon sampler lined with 1-inch-high brass rings. The central portions of the driven samples were placed in sealed containers and transported to our laboratory for testing and analysis. The approximate exploratory locations are shown on Plate 1 and descriptive logs are presented in Appendix B.
Laboratory Testing Maximum dry density/optimum moisture content, expansion potential, pH, resistivity, sulfate content, chloride content, direct shear, and in-situ density/moisture content were determined for selected undisturbed and bulk samples of earth materials, considered representative of those encountered. An evaluation of the test data is reflected throughout the Conclusions and Recommendations section of this report. A brief description of laboratory test criteria and summaries of test data are presented in Appendix C.
FINDINGS
Regional Geology The site is located in the Peninsular Ranges Geomorphic Province of California. The Peninsular Ranges are characterized by northwest trending steep mountain ranges bounded by sediment filled elongated valleys. The dominant geomorphic features reflect the northwest trend of the province. Associated with and subparallel to the San Andreas Fault are the San Jacinto Fault, Newport-Inglewood, and the Whittier-Elsinore Fault. The Santa Ana Mountains abut the west side of the Elsinore Fault while the Perris Block forms the other side of the fault zone to the east. The Perris Block is bounded to the east by the San Jacinto Fault. The northern perimeter of the Los Angeles basin forms part of a northerly dipping blind thrust fault at the boundary between the Peninsular Ranges and the Transverse Range. The mountainous regions within the Peninsular Ranges Province are comprised of Pre-Cretaceous, metasedimentary, and metavolcanic rocks along with Cretaceous plutonic rocks of the Southern California Batholith. The low lying areas are primarily comprised of Tertiary and Quaternary non-marine alluvial sediments consisting of alluvial deposits, sandstones, claystones, siltstones, conglomerates, and
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occasional volcanic units. A map illustrating the regional geology is presented on the Regional Geologic Map, Figure 2.
Local Geology The earth materials on the site are primarily comprised of Quaternary alluvial materials. A general description of the dominant earth materials observed on the site is provided below:
• Quaternary Young Alluvial Valley Deposits (map symbol Qyv): Quaternary alluvial materials were encountered to the maximum depth explored. The alluvial deposits were noted to consist of dark grayish brown, fine to coarse grained silty sand. These deposits were generally noted to be in slightly moist and loose to medium dense state.
Mr. Dan Locke Proposed Additions and Additional Dwelling Unit Project No. 23009-10A Date: January 2024
First Ascent Geotechnical Engineering
REGIONAL GEOLOGIC MAP FIGURE 2
Qyv – Quaternary
Young Alluvial Valley
Deposits
Quaternary Pauba
Formation
Approximate Site Location
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Faulting The project is located in a seismically active region and as a result, significant ground shaking will likely impact the site within the design life of the proposed project. The geologic structure of the entire southern California area is dominated by northwest-trending faults associated with the San Andreas Fault system, which accommodates for most of the right lateral movement associated with the relative motion between the Pacific and North American tectonic plates. Major known active faults within the region include the Elsinore, San Jacinto and San Andreas Faults. While no active faults are known to project through the site, the site is located within the Alquist-Priolo Earthquake Fault Zone, established for the Elsinore (Wildomar) Fault, by the State of California to restrict the construction of new habitable structures across identifiable traces of known active faults. An active fault is defined by the State of California as having surface displacement within the past 11,000 years or during the Holocene geologic time period. The Elsinore Fault is considered active with offsets younger than 2,000 years (Rockwell & Lamar, 1986). The Elsinore Fault is a right lateral strike-slip fault that generally trends in a northwest to southeast direction. Locally, the Temecula segment of the fault is estimated to produce a maximum earthquake magnitude of 7.07. The Wildomar Fault and the Elsinore Fault zone is delineated on local geologic maps (Figure 2), Riverside County GIS maps (Figure 3), and State of California Alquist-Priolo Special Studies Maps (Figure 4). The northeastern portion of the site is located within the Elsinore Fault Zone. The location of the Elsinore Fault is generally well studied and well-established. According to the Riverside County GIS and California Geologic Survey maps the Elsinore Fault is located approximately 385 feet northeast of the subject site. Evaluation of on-site fault hazard potential associated with the Elsinore Fault remains unevaluated and is outside the scope of this investigation. Based on our review of regional geologic maps and applicable computer programs (USGS Seismic Design Maps and USGS Earthquake Hazard Programs), the Elsinore Fault with an approximate source to site distance of 0.12 kilometers is the closest known active fault anticipated to produce the highest ground accelerations, with an anticipated maximum modal magnitude of 7.07. A list of faults within a 100km radius of the subject site are included in Appendix D.
Landslides
Landslide debris was not observed during our subsurface exploration and no ancient landslides are known to exist on the site. No landslides are known to exist, or have been mapped, in the vicinity of the site. Geologic mapping of the site conducted during our investigation, and review of aerial imagery of the site, reveal no geomorphic expressions indicative of land sliding.
Mr. Dan Locke Proposed Additions and Additional Dwelling Unit Project No. 23009-10A Date: January 2024
First Ascent Geotechnical Engineering
COUNTY FAULT MAP FIGURE 3
Site Location
Mr. Dan Locke Proposed Additions and Additional Dwelling Unit Project No. 23009-10A Date: January 2024
First Ascent Geotechnical Engineering
STATE AP FAULT MAP FIGURE 4
Approximate Site Location
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CONCLUSIONS AND RECOMMENDATIONS
General From a construction feasibility point of view, the subject property is considered suitable for the proposed development. However, the fault hazard potential posed by the Elsinore (Wildomar) Fault remains unevaluated and is outside the scope of this investigation. The main geotechnical issue affecting the proposed development is the presence of loose near surface soils. The following conclusions and recommendations should be incorporated into the plans and implemented during construction.
Earthwork
Earthwork and Grading The provisions of the 2022 California Building Code (CBC), including the General Earthwork and Grading Specifications in the last Appendix of this report, should be applied to all earthwork and grading operations, as well as in accordance with all applicable grading codes and requirements of the appropriate reviewing agency. Unless specifically revised or amended herein, grading operations should also be performed in accordance with applicable provisions of our General Earthwork and Grading Specifications within the last appendix of this report.
Clearing and Grubbing Vegetation including trees, grasses, weeds, brush, shrubs, or any other debris should be stripped from the areas to be graded and properly disposed of offsite. In addition, laborers should be utilized to remove any roots, branches, or other deleterious materials during grading operations. First Ascent Geotechnical Engineering should be notified at the appropriate times to provide observation and testing services during Clearing and Grubbing operations. Any buried structures or unanticipated conditions should be brought to our immediate attention.
Excavation Characteristics Based on the results of our exploration and experience with similar projects in similar settings, the near surface earth materials, will be readily excavated with conventional earth moving equipment.
Groundwater Groundwater was not observed during our subsurface exploration. Local well data from the California Department of Water Resources Water Data Library indicates observation wells in the vicinity of the subject site. Well number 334996N1171201W001, located approximately 1 mile to the northeast, indicates monitoring from January 2012 to present. During that time the high groundwater mark was measured to be 280 feet below ground surface. According to the Seismic Hazard Zone Report for the Temecula 7.5’ Quadrangle, prepared by the California Geologic Survey (CGS 2018) the historic high groundwater mark in the vicinity of the subject site is between 10 and 20 feet below ground surface.
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Ground Preparation For each area to receive compacted fill, the removal of low density, compressible earth materials, such as topsoil and upper alluvial materials, and undocumented artificial fill, should continue until firm competent alluvium is encountered. Removal excavations are subject to verification by the project engineer, geologist or their representative. Prior to placing compacted fills, the exposed bottom in each removal area should be scarified to a depth of 6 inches or more, watered or air dried as necessary to achieve near optimum moisture conditions and then compacted to a minimum of 90 percent of the maximum dry density determined by ASTM D 1557. The intent of remedial grading is to diminish the potential for hydro-consolidation, slope instability, and/or settlement. Remedial grading should extend beyond the perimeter of the proposed structures a horizontal distance equal to the depth of excavation or a minimum of 5 feet, whichever is greater. In general, the anticipated over excavation depths should extend to a depth of 3 feet below footing depths or existing grade, whichever is greater. No grading is proposed for the existing barn conversion. Prior to placement of the new concrete slab, the exposed soil within the building footprint should be compacted to a minimum of 90 percent of the maximum dry density to a depth of 12 inches below the slab. Compacted Fill Testing Compacted fill materials should be placed in 6 to 8 inch maximum (uncompacted) lifts, watered or air dried as necessary to achieve uniform near optimum moisture content and then compacted to a minimum of 90 percent of the maximum dry density determined by ASTM D 1557.
Fill Slopes When properly constructed, fill slopes up to 10 feet high with inclinations of 2:1 (h:v) or flatter are considered to be grossly stable. Keyways are required at the toe of all fill slopes higher than 5 feet and steeper than 5:1 (h:v). Keyways should be a minimum of 10 feet wide and 2 feet into competent earth materials, as measured on the downhill side. In order to establish keyway removals, backcuts should be cut no steeper than 1:1 or as recommended by the project geologist or engineer.
Import Earth Materials Should import earth materials be needed to achieve final design grades, all potential import materials should be free of deleterious/oversize materials, non-expansive, non-corrosive and approved by the project geotechnical consultant prior to delivery onsite. Per the California department of toxic control (DTSC) guidelines, import materials may be subjected to environmental testing. To avoid this, the source of the import materials should not be from undesirable commercial sites that have been subjected to environmental contaminants.
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Cut/Fill Transitions Cut/fill transitions should be eliminated from all building areas where the depth of fill placed within the “fill” portion exceeds proposed footing depths. This is to diminish distress to structures resulting from excessive differential settlement. The entire foundation of each structure should be founded on a uniform bearing material. This should be accomplished by overexcavating the “cut” portion and replacing the excavated materials as properly compacted fill. Refer to the following table for recommended depths of overexcavation.
DEPTH OF FILL (“fill” portion) DEPTH OF OVEREXCAVATION (“cut” portion) Up to 5 feet Equal Depth 5 to 10 feet 5 feet Greater than 10 feet One-half the thickness of fill placed on the “fill” portion (10 feet maximum) Overexcavation of the “cut” portion should extend beyond the building perimeter a horizontal distance equal to the depth of overexcavation or a minimum of 5 feet, whichever is greater.
Cut Areas In cut areas, an area a minimum of 5 feet beyond the footprint of the proposed structures should overexcavated until; competent bottoms are achieved; to a minimum 3 feet below the proposed foundations; or per the Overexcavation Table above; (whichever is greater) and replaced with compacted fill. Final determination of areas that require overexcavation should be determined in the field by a representative of First Ascent Geotechnical Engineering.
Post Grading Considerations
Site Drainage Control of site drainage is important for the performance of the proposed project. Roof gutters are recommended for the proposed structures. Pad and roof drainage should be directed away from building foundations and collected and transferred to driveways, adjacent streets, storm-drain facilities, or other locations approved by the building official in non-erosive drainage devices. Drainage should not be allowed to pond on the pad or against any foundation or retaining wall. Drainage should not be allowed to flow uncontrolled over any descending slope. Planters located within retaining wall backfill should be sealed to prevent moisture intrusion into the backfill. Planters located next to structures should be sealed to the depth of the footings. Drainage control devices require periodic cleaning, testing and maintenance to remain effective. At a minimum, pad drainage should be designed at the minimum gradients required by the CBC. To divert water away from foundations, the ground surface adjacent to foundations should also be graded at the minimum gradients required per the CBC.
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Utility Trenches All utility trench backfill should be compacted at near optimum moisture to a minimum of 90 percent of the maximum dry density determined by ASTM D 1557. For utility trench backfill within pavement areas the upper 6 inches of subgrade materials should be compacted to 95 percent of the maximum dry density determined by ASTM D 1557. This includes within the street right-of-ways, utility easements, under footings, sidewalks, driveways and building floor slabs, as well as within or adjacent to any slopes. Backfill should be placed in approximately 6 to 8 inch maximum loose lifts and then mechanically compacted with a hydro-hammer, rolling with a sheepsfoot, pneumatic tampers, or similar equipment. The utility trenches should be tested by the project geotechnical engineer or their representative to verify minimum compaction requirements are obtained. In order to minimize the penetration of moisture below building slabs, all utility trenches should be backfilled with compacted fill, lean concrete or concrete slurry where they undercut the perimeter foundation. Utility trenches that are proposed parallel to any building footings (interior and/or exterior trenches), should not be located within a 1:1 (h:v) plane projected downward from the outside bottom edge of the footing.
SEISMIC DESIGN CONSIDERATIONS
Ground Motions Structures are required to be designed and constructed to resist the effects of seismic ground motions as provided in the 2022 California Building Code Section 1613. The design is dependent on the site class, occupancy category I, II, III, or IV, mapped spectral accelerations for short periods (Ss), and mapped spectral acceleration for a 1-second period (S1). In order for structural design to comply with the 2022 CBC, the USGS “US Seismic Design Maps” online tool was used to compile spectral accelerations for the subject property based on data and maps jointly compiled by the United States Geological Survey (USGS) and the California Geological Survey (CGS). The seismic design coefficients were determined by a combination of the site class, mapped spectral accelerations, and occupancy category. The following seismic design coefficients should be implemented during design of the proposed structures. Summaries of the Seismic data are presented in Appendix D.
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2022 CBC Value Site Location Latitude: 33.486678˚ (North) Longitude: -117.131289˚(West) Site Class D-Default Mapped Spectral Accelerations for short periods, Ss 1.595g Mapped Spectral Accelerations for 1-Second Period, S1 0.593g Maximum Considered Earthquake Spectral Response Acceleration for Short Periods, Sms 1.914g Design Spectral Response Acceleration for Short Periods, SDS 1.276g Site amplification factor, Fa 1.2g Site Modified Peak Ground Acceleration, PGAm 0.861 Seismic Design Category D Importance Factor Based on Occupancy Category II Actual ground shaking intensities at the site may be substantially higher or lower based on complex variables such as the near source directivity effects, depth and consistency of earth materials, topography, geologic structure, direction of fault rupture, and seismic wave reflection, refraction, and attenuation rates.
TENTATIVE FOUNDATION DESIGN RECOMMENDATIONS
General Based on the site soil properties and the bearing capacity calculations shallow foundations and concrete slabs on grade are considered feasible for support of the proposed structures, provided the foundations are designed and constructed in accordance with the recommendations of this report.
Allowable Bearing Values The Terzaghi equation was utilized to estimate the bearing capacity of the native soil beneath the existing barn structure. An allowable bearing value of 1,500 pounds per square foot (psf) is recommended for design of shallow continuous footings for the proposed additional dwelling unit. For structural additions to be founded in compacted fill at an assumed minimum depth of 12 inches below the lowest adjacent final grade, an allowable bearing value of 2,000 pounds per square foot (psf) can be utilized.
Lateral Resistance The resistance between the soil and the structure, also known as the soil-structure interaction, plays a crucial role in the stability and performance of a foundation system. It is commonly expressed as a percentage of the dead load, which refers to the weight of the structure and any permanent loads it carries. The resistance between the soil and the structure can be attributed to several factors: Friction: The frictional resistance between the soil and the structure occurs along the contact surface. It depends on the roughness of the interface and the normal force acting between them. Frictional resistance helps to transfer the load from the structure to the soil.
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Adhesion: Adhesion refers to the bonding or sticking of the soil particles to the structure. It occurs due to the cohesive properties of the soil and can enhance the resistance between the soil and the structure, especially in cohesive soils. Passive Earth Pressure: In some cases, the soil can exert a passive earth pressure against the structure, particularly when the structure displaces the soil laterally. This resistance can contribute to the overall stability of the structure. The resistance between the soil and the structure is influenced by various factors, including the type and properties of the soil, the geometry and characteristics of the structure, and the applied loads. It is essential to consider these factors during the design and analysis of the foundation system to ensure its stability and prevent excessive settlement or failure. When expressing the resistance as a percentage of the dead load, it provides an indication of the level of support provided by the soil relative to the weight of the structure. Given the site soil properties, passive earth pressure of 180 psf per foot of depth may be used to establish lateral bearing resistance for footings. A coefficient of friction of 0.45 times the dead load forces may be used between concrete and the supporting earth materials to determine lateral sliding resistance.
Foundation Observations In accordance with the 2022 CBC and prior to the placement of forms, concrete, or steel, all foundation excavations should be observed by the geologist, engineer, or his representative to verify that they have been excavated into competent bearing materials. The excavations should be per the approved plans, moistened, cleaned of all loose materials, trimmed neat, level, and square. Any moisture softened earth materials should be removed prior to steel or concrete placement. Earth materials from foundation excavations should not be placed in slab on grade areas unless the materials are tested for expansion potential and compacted to a minimum of 90 percent of the maximum dry density.
Expansive Soil Considerations Preliminary laboratory test results indicate onsite earth materials exhibit an expansion potential of VERY
LOW as classified in accordance with 2022 CBC Section 1803.5.3 and ASTM D 4829. Additional, testing for expansive soil conditions should be conducted upon completion of rough grading. The following recommendations should be considered the very minimum requirements, for the earth materials tested. It is common practice for the project architect or structural engineer to require additional slab thickness, footing sizes, and/or reinforcement.
Building Floor Slabs
• Building floor slabs should be a minimum of 5 inches thick and reinforced with a minimum of No. 4 bars spaced a maximum of 12 inches on center, each way. All floor slab reinforcement should be supported on concrete chairs or bricks to ensure the desired placement at mid-depth.
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• Interior floor slabs, within moisture sensitive areas, should be underlain by a minimum 10-mil thick moisture/vapor barrier to help reduce the upward migration of moisture from the underlying earth materials. The moisture/vapor barrier used should meet the performance standards of an ASTM E 1745 Class A material, and be properly designed and constructed according to the American Concrete Institute 302.1 R, Concrete Floor and Slab Construction. It is the responsibility of the contractor to ensure that the moisture/vapor barriers are free of openings, rips, or punctures prior to placing concrete. Ultimately, the design of the moisture/vapor barrier system and recommendations for concrete placement and curing are the purview of the foundation engineer, taking into consideration the project requirements provided by the architect and owner.
• Garage floor slabs should be a minimum of 4 inches thick and should be reinforced in a similar manner as living area floor slabs.
Corrosivity Corrosion is defined by the National Association of Corrosion Engineers (NACE) as “a deterioration of a substance or its properties because of a reaction with its environment.” From a geotechnical viewpoint, the “substances” are the reinforced concrete foundations or buried metallic elements (not surrounded by concrete) and the “environment” is the prevailing earth materials in contact with them. Many factors can contribute to corrosivity, including the presence of chlorides, sulfates, salts, organic materials, different oxygen levels, poor drainage, different soil types, and moisture content. It is not considered practical or realistic to test for all of the factors which may contribute to corrosivity. The potential for concrete exposure to chlorides is based upon the recognized Caltrans reference standard “Bridge Design Specifications”, under Subsection 8.22.1 of that document, Caltrans has determined that “Corrosive water or soil contains more than 500 parts per million (ppm) of chlorides”. Based on limited preliminary laboratory testing, the onsite earth materials have chloride contents less than 500 ppm. Specific guidelines for concrete mix design are provided in 2022 CBC Section 1904.1 and ACI 318-19, Section 4.3 Tables 19.3.1.1 and 19.3.2.1 when the soluble sulfate content of earth materials exceeds 0.1 percent by weight. Based on limited preliminary laboratory testing, the onsite earth materials are classified in accordance with Tables 19.3.1.1 and 19.3.2.1 as having a negligible sulfate exposure condition. Based on our laboratory testing of resistivity, the onsite earth materials in contact with buried steel should be considered moderately corrosive. Additionally, pH values below 5.6 and above 9.1 are recognized as being corrosive to many common metallic components. The pH values for the earth materials tested were lower than 9.1 and higher than 5.6. The preliminary test results for corrosivity are based on limited samples, and the initiation of grading may blend various earth materials together. This blending or imported material could alter and increase the detrimental properties of the onsite earth materials. Accordingly, additional testing for chlorides and sulfates along with testing for pH and resistivity should be performed upon completion of grading. Laboratory test results are presented in Appendix C.
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CONCRETE FLATWORK
Thickness and Joint Spacing Concrete sidewalks and patio type slabs should be at least 3½ inches thick and provided with construction or expansion joints every 6 feet or less, to reduce the potential for excessive cracking.
Subgrade Preparation In order to reduce the potential for unsightly cracking, subgrade earth materials underlying concrete flatwork should be compacted at near optimum moisture to a minimum of 90 percent of the maximum dry density determined by ASTM D 1557 and then moistened to optimum or slightly above optimum moisture content. This moisture should extend to a depth of 12 inches below subgrade and be maintained prior to placement of concrete. Pre-watering of the earth materials prior to placing concrete will promote uniform curing of the concrete and minimize the development of shrinkage cracks. The project geotechnical engineer or his representative should verify the density and moisture content of the earth materials and the depth of moisture penetration prior to placing concrete. Cracking within concrete flatwork is often a result of factors such as the use of too high a water to cement ratio and/or inadequate steps taken to prevent moisture loss during the curing of the concrete. Concrete distress can be reduced by proper concrete mix design and proper placement and curing of the concrete. Minor cracking within concrete flatwork is normal and should be expected.
GRADING PLAN REVIEW AND CONSTRUCTION SERVICES This report has been prepared for the exclusive use of Dan Locke and their authorized representative. It likely does not contain sufficient information for other parties or other uses. First Ascent Geotechnical Engineering should be engaged to review the final design plans and specifications prior to construction. This is to verify that the recommendations contained in this report have been properly incorporated into the project plans and specifications. Should First Ascent Geotechnical Engineering not be accorded the opportunity to review the project plans and specifications, we are not responsibility for misinterpretation of our recommendations. We recommend that First Ascent Geotechnical Engineering be retained to provide geologic and geotechnical engineering services during grading and foundation excavation phases of the work. In order to allow for design changes in the event that the subsurface conditions differ from those anticipated prior to construction. First Ascent Geotechnical Engineering should review any changes in the project and modify and approve in writing the conclusions and recommendations of this report. This report and the drawings contained
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within are intended for design input purposes only and are not intended to act as construction drawings or specifications. In the event that conditions encountered during grading or construction operations appear to be different than those indicated in this report, this office should be notified immediately, as revisions may be required.
REPORT LIMITATIONS Our services were performed using the degree of care and skill ordinarily exercised, under similar circumstances, by reputable soils engineers and geologists, practicing at the time and location this report was prepared. No other warranty, expressed or implied, is made as to the conclusions and professional advice included in this report. Earth materials vary in type, strength, and other geotechnical properties between points of observation and exploration. Groundwater and moisture conditions can also vary due to natural processes or the works of man on this or adjacent properties. As a result, we do not and cannot have complete knowledge of the subsurface conditions beneath the subject property. No practical study can completely eliminate uncertainty with regard to the anticipated geotechnical conditions in connection with a subject property. The conclusions and recommendations within this report are based upon the findings at the points of observation and are subject to confirmation by First Ascent Geotechnical Engineering based on the conditions revealed during grading and construction. This report was prepared with the understanding that it is the responsibility of the owner or their representative, to ensure that the conclusions and recommendations contained herein are brought to the attention of the other project consultants and are incorporated into the plans and specifications. The owners’ contractor should properly implement the conclusions and recommendations during grading and construction, and notify the owner if they consider any of the recommendations presented herein to be unsafe or unsuitable.
APPENDIX A REFERENCES
APPENDIX A
References California Building Standards Commission, 2022, 2022 California Building Code, California Code of
Regulations Title 24, Part 2, Volume 2 of 2, Based on 2018 International Building Code. California Geological Survey, Geologic Map of the Oceanside 30 X 60 Quadrangles (Kennedy and Tan 2007) California Geologic Survey, 2018, seismic Hazard Zone Report for the Temecula 7.5-Minute Quadrangle, Riverside County California California Geological Survey, 2023, EQ Zapp: California Earthquake Hazards Zone Application National Bureau of Standards, 1989, Underground corrosion Circular 579. OSHPD, 2023, U.S. Seismic Design Maps, https://seismicmaps.org/ Per A.B. Chance® Recommendations, 2003
APPENDIX B EXPLORATORY LOGS
Project Name: Cabrillo Avenue
Logged By: HR
Type of Rig: Hand Auger
Hole Location: See Geotechnical Map
Quaternary Young Alluvial Valley Deposits (Qyv)
No Groundwater
Total Depth 8 feet
coarse sand
medium dense below 5 feet
UNIT DESCRIPTION
Silty SAND, dark grayish brown, slightly moist, loose, fine to coarse sand
30
25
20
15
10
7 107.8 7.2
6.755.5 101.7
4 101.2
104.1 6.0
6.5
SM
2.5
Page: 1 of 1
Project Number: 23009-10A
Drilling Company: First Ascent
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Hole Diameter (in): 8
First Ascent Geotechnical Engineering, LLC
Geologic Boring Log B-1
Date: 12/9/2023
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Project Name: Cabrillo Avenue
Logged By: HR
Type of Rig: Hand Auger
Geologic Boring Log B-2
Date: 12/9/2023 Page: 1 of 1
Project Number: 23009-10A
Drilling Company: First Ascent
Hole Diameter (in): 8
Hole Location: See Geotechnical Map
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UNIT DESCRIPTION
0 0 110.4 4.9 Quaternary Young Alluvial Valley Deposits (Qyv)
SM Silty SAND, dark grayish brown, slightly moist, loose, fine to coarse sand
2.5 104.8 5.6
4 100.0 12.45 Total Depth 5 feet
No Groundwater
10
15
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First Ascent Geotechnical Engineering, LLC
30
APPENDIX C LABORATORY PROCEDURES AND TEST RESULTS
APPENDIX C
Laboratory Procedures and Test Results Laboratory testing provided quantitative and qualitative data involving the relevant engineering properties of the representative earth materials selected for testing. The representative samples were tested in general accordance with American Society for Testing and Materials (ASTM) procedures and/or California Test Methods (CTM).
Soil Classification: Earth materials encountered during exploration were classified and logged in general accordance with the Standard Practice for Description and Identification of Soils (Visual-Manual Procedure) of ASTM D 2488. Upon completion of laboratory testing, exploratory logs and sample descriptions were reconciled to reflect laboratory test results with regard to ASTM D 2487.
Moisture and Density Tests: For select samples moisture content was determined using the guidelines of ASTM D 2216 and dry density determinations were made using the guidelines of ASTM D 2937. These tests were performed on relatively undisturbed samples and the test results are presented on the exploratory logs.
Maximum Density Tests: The maximum dry density and optimum moisture content of representative samples were determined using the guidelines of ASTM D 1557. The test results are presented in the table below.
SAMPLE
LOCATION
MATERIAL
DESCRIPTION
MAXIMUM DRY
DENSITY (pcf)
OPTIMUM MOISTURE
CONTENT (%) B-2 @ 0-5 feet Silty SAND 124.0 9.4
Expansion Index: The expansion potential of representative samples was evaluated using the guidelines of ASTM D 4829. The test results are presented in the table below.
SAMPLE
LOCATION
MATERIAL
DESCRIPTION EXPANSION INDEX EXPANSION POTENTIAL B-2 @ 0-5 feet Silty SAND 0 Very Low
Minimum Resistivity and pH Tests: Minimum resistivity and pH Tests of select samples were performed using the guidelines of CTM 643. The test results are presented in the table below.
SAMPLE
LOCATION
MATERIAL
DESCRIPTION pH MINIMUM RESISTIVITY
(ohm-cm) B-2 @ 0-5 feet Silty SAND 7.5 8100
Soluble Sulfate: The soluble sulfate content of select samples was determined using the guidelines of CTM 417. The test results are presented in the table below.
SAMPLE
LOCATION
MATERIAL
DESCRIPTION
SULFATE CONTENT
(% by weight) SULFATE EXPOSURE B-2 @ 0-5 feet Silty SAND 0.003 Negligible
Chloride Content: Chloride content of select samples was determined using the guidelines of CTM 422. The test results are presented in the table below.
SAMPLE LOCATION MATERIAL DESCRIPTION CHLORIDE CONTENT (ppm) B-2 @ 0-5 feet Silty SAND 11
Direct Shear: Direct shear tests were performed on representative undisturbed samples using the guidelines of ASTM D 3080. The test results are presented in the table below
SAMPLE LOCATION MATERIAL
DESCRIPTION
FRICTION ANGLE
(degrees)
APPARENT COHESION
(psf) B-1 @ 2.5 feet Silty SAND 33 41 B-2 @ 4 feet Silty SAND 34 54
APPENDIX D SEISMICITY
1/16/24, 6:02 PM 2008 National Seismic Hazard Maps - Source Parameters
https://earthquake.usgs.gov/cfusion/hazfaults_2008_search/query_results.cfm 1/6
2008 National Seismic Hazard Maps - Source Parameters
New Search
Distance in
Kilometers Name State
Pref
Slip
Rate
(mm/yr)
Dip
(degrees)
Dip
Dir
Slip
Sense
Rupture
Top
(km)
Rupture
Bottom
(km)
Length
(km)
0.12 Elsinore;GI+T+J+CM CA n/a 86 NE strike
slip 0 16 195
0.12 Elsinore;T CA 5 90 V strike
slip 0 14 52
0.12 Elsinore;GI+T CA 5 90 V strike
slip 0 14 78
0.12 Elsinore;W+GI+T+J+CM CA n/a 84 NE strike
slip 0 16 241
0.12 Elsinore;W+GI+T+J CA n/a 84 NE strike
slip 0 16 199
0.12 Elsinore;W+GI+T CA n/a 84 NE strike
slip 0 14 124
0.12 Elsinore;T+J+CM CA n/a 85 NE strike
slip 0 16 169
0.12 Elsinore;T+J CA n/a 86 NE strike
slip 0 17 127
0.12 Elsinore;GI+T+J CA n/a 86 NE strike
slip 0 17 153
19.77 Elsinore;J+CM CA 3 84 NE strike
slip 0 17 118
19.77 Elsinore;J CA 3 84 NE strike
slip 0 19 75
20.48 Elsinore;GI CA 5 90 V strike
slip 0 13 37
20.48 Elsinore;W+GI CA n/a 81 NE strike
slip 0 14 83
34.14 San Jacinto;A+CC+B CA n/a 90 V strike
slip 0.1 15 152
34.14 San Jacinto;A+CC+B+SM CA n/a 90 V strike
slip 0.1 15 178
34.14 San Jacinto;A+C CA n/a 90 V strike
slip 0 17 118
U.S. Geological Survey - Earthquake Hazards Program
1/16/24, 6:02 PM 2008 National Seismic Hazard Maps - Source Parameters
https://earthquake.usgs.gov/cfusion/hazfaults_2008_search/query_results.cfm 2/6
34.14 San Jacinto;A+CC CA n/a 90 V strike
slip 0 16 118
34.14 San Jacinto;A CA 9 90 V strike
slip 0 17 71
34.21 San Jacinto;SBV+SJV+A+CC CA n/a 90 V strike
slip 0 16 181
34.21 San Jacinto;SBV+SJV+A CA n/a 90 V strike
slip 0 16 134
34.21 San Jacinto;SJV+A+CC+B+SM CA n/a 90 V strike
slip 0.1 15 196
34.21 San Jacinto;SJV+A+CC+B CA n/a 90 V strike
slip 0.1 15 170
34.21 San Jacinto;SJV+A+CC CA n/a 90 V strike
slip 0 16 136
34.21 San Jacinto;SJV+A+C CA n/a 90 V strike
slip 0 17 136
34.21 San Jacinto;SJV+A CA n/a 90 V strike
slip 0 17 89
34.21 San Jacinto;SBV+SJV+A+CC+B CA n/a 90 V strike
slip 0.1 15 215
34.21 San Jacinto;SBV+SJV+A+C CA n/a 90 V strike
slip 0 17 181
34.21 San Jacinto;SBV+SJV+A+CC+B+SM CA n/a 90 V strike
slip 0.1 15 241
36.55 San Jacinto;SJV CA 18 90 V strike
slip 0 16 43
36.55 San Jacinto;SBV+SJV CA n/a 90 V strike
slip 0 16 88
44.73 Newport Inglewood Connected alt 2 CA 1.3 90 V strike
slip 0 11 208
44.73 Newport Inglewood Connected alt 1 CA 1.3 89 strike
slip 0 11 208
44.73 Newport-Inglewood (O shore)CA 1.5 90 V strike
slip 0 10 66
48.72 Rose Canyon CA 1.5 90 V strike
slip 0 8 70
51.95 San Joaquin Hills CA 0.5 23 SW thrust 2 13 27
54.63 San Jacinto;CC+B CA n/a 90 V strike
slip 0.2 14 77
54.63 San Jacinto;CC+B+SM CA n/a 90 V strike
slip 0.2 14 103
1/16/24, 6:02 PM 2008 National Seismic Hazard Maps - Source Parameters
https://earthquake.usgs.gov/cfusion/hazfaults_2008_search/query_results.cfm 3/6
54.63 San Jacinto;CC CA 4 90 V strike
slip 0 16 43
55.06 Chino, alt 2 CA 1 65 SW strike
slip 0 14 29
57.08 Elsinore;W CA 2.5 75 NE strike
slip 0 14 46
57.35 San Jacinto;C CA 14 90 V strike
slip 0 17 47
59.28 Chino, alt 1 CA 1 50 SW strike
slip 0 9 24
59.66 San Jacinto;SBV CA 6 90 V strike
slip 0 16 45
59.71 S. San Andreas;CH+CC+BB+NM+SM+NSB+SSB+BG CA n/a 86 strike
slip 0 14 442
59.71 S. San Andreas;SSB+BG+CO CA n/a 77 strike
slip 0.2 12 170
59.71 S. San Andreas;CC+BB+NM+SM+NSB+SSB+BG+CO CA n/a 86 strike
slip 0.1 13 449
59.71 S. San Andreas;BG CA n/a 58 strike
slip 0 13 56
59.71 S. San Andreas;CC+BB+NM+SM+NSB+SSB+BG CA n/a 85 strike
slip 0 14 380
59.71 S. San Andreas;SM+NSB+SSB+BG+CO CA n/a 83 strike
slip 0.1 13 303
59.71 S. San Andreas;SM+NSB+SSB+BG CA n/a 81 strike
slip 0 13 234
59.71 S. San Andreas;BG+CO CA n/a 72 strike
slip 0.3 12 125
59.71 S. San
Andreas;CH+CC+BB+NM+SM+NSB+SSB+BG+CO CA n/a 86 strike
slip 0.1 13 512
59.71 S. San Andreas;NSB+SSB+BG CA n/a 75 strike
slip 0 14 136
59.71 S. San
Andreas;PK+CH+CC+BB+NM+SM+NSB+SSB+BG CA n/a 86 strike
slip 0.1 13 479
59.71 S. San
Andreas;PK+CH+CC+BB+NM+SM+NSB+SSB+BG+CO CA n/a 86 strike
slip 0.1 13 548
59.71 S. San Andreas;BB+NM+SM+NSB+SSB+BG+CO CA n/a 85 strike
slip 0.1 13 390
59.71 S. San Andreas;SSB+BG CA n/a 71 strike
slip 0 13 101
1/16/24, 6:02 PM 2008 National Seismic Hazard Maps - Source Parameters
https://earthquake.usgs.gov/cfusion/hazfaults_2008_search/query_results.cfm 4/6
59.71 S. San Andreas;NSB+SSB+BG+CO CA n/a 79 strike
slip 0.2 12 206
59.71 S. San Andreas;BB+NM+SM+NSB+SSB+BG CA n/a 84 strike
slip 0 14 321
59.71 S. San Andreas;NM+SM+NSB+SSB+BG CA n/a 83 strike
slip 0 14 271
59.71 S. San Andreas;NM+SM+NSB+SSB+BG+CO CA n/a 84 strike
slip 0.1 13 340
59.79 S. San Andreas;NM+SM+NSB+SSB CA n/a 90 V strike
slip 0 13 213
59.79 S. San Andreas;BB+NM+SM+NSB+SSB CA n/a 90 V strike
slip 0 14 263
59.79 S. San Andreas;SSB CA 16 90 V strike
slip 0 13 43
59.79 S. San Andreas;SM+NSB+SSB CA n/a 90 V strike
slip 0 13 176
59.79 S. San Andreas;PK+CH+CC+BB+NM+SM+NSB+SSB CA n/a 90 V strike
slip 0.1 13 421
59.79 S. San Andreas;NSB+SSB CA n/a 90 V strike
slip 0 13 79
59.79 S. San Andreas;CC+BB+NM+SM+NSB+SSB CA n/a 90 V strike
slip 0 14 322
59.79 S. San Andreas;CH+CC+BB+NM+SM+NSB+SSB CA n/a 90 V strike
slip 0 14 384
61.02 Earthquake Valley CA 2 90 V strike
slip 0 19 20
72.45 Palos Verdes Connected CA 3 90 V strike
slip 0 10 285
72.45 Coronado Bank CA 3 90 V strike
slip 0 9 186
73.58 Pinto Mtn CA 2.5 90 V strike
slip 0 16 74
74.07 S. San Andreas;SM+NSB CA n/a 90 V strike
slip 0 13 133
74.07 S. San Andreas;CC+BB+NM+SM+NSB CA n/a 90 V strike
slip 0 14 279
74.07 S. San Andreas;PK+CH+CC+BB+NM+SM+NSB CA n/a 90 V strike
slip 0.1 13 377
74.07 S. San Andreas;NM+SM+NSB CA n/a 90 V strike
slip 0 13 170
1/16/24, 6:02 PM 2008 National Seismic Hazard Maps - Source Parameters
https://earthquake.usgs.gov/cfusion/hazfaults_2008_search/query_results.cfm 5/6
74.07 S. San Andreas;CH+CC+BB+NM+SM+NSB CA n/a 90 V strike
slip 0 14 341
74.07 S. San Andreas;NSB CA 22 90 V strike
slip 0 13 35
74.07 S. San Andreas;BB+NM+SM+NSB CA n/a 90 V strike
slip 0 14 220
75.92 Newport-Inglewood, alt 1 CA 1 88 strike
slip 0 15 65
76.70 Palos Verdes CA 3 90 V strike
slip 0 14 99
81.86 Cucamonga CA 5 45 N thrust 0 8 28
82.14 Puente Hills (Coyote Hills)CA 0.7 26 N thrust 2.8 15 17
84.71 Burnt Mtn CA 0.6 67 W strike
slip 0 16 21
86.54 San Jose CA 0.5 74 NW strike
slip 0 15 20
88.17 Cleghorn CA 3 90 V strike
slip 0 16 25
88.59 S. San Andreas;CO CA 20 90 V strike
slip 0.6 11 69
90.03 Eureka Peak CA 0.6 90 V strike
slip 0 15 19
90.38 Sierra Madre CA 2 53 N reverse 0 14 57
90.38 Sierra Madre Connected CA 2 51 reverse 0 14 76
91.57 San Jacinto;B CA 4 90 V strike
slip 0.7 13 34
91.57 San Jacinto;B+SM CA n/a 90 V strike
slip 0.4 12 61
93.00 North Frontal (West)CA 1 49 S reverse 0 16 50
93.25 Elsinore;CM CA 3 82 NE strike
slip 0 13 39
95.90 Puente Hills (Santa Fe Springs)CA 0.7 29 N thrust 2.8 15 11
97.44 Helendale-So Lockhart CA 0.6 90 V strike
slip 0 13 114
99.14 North Frontal (East)CA 0.5 41 S thrust 0 16 27
99.83 S. San Andreas;CH+CC+BB+NM+SM CA n/a 90 V strike
slip 0 14 306
99.83 S. San Andreas;CC+BB+NM+SM CA n/a 90 V strike
slip 0 14 243
1/16/24, 6:02 PM 2008 National Seismic Hazard Maps - Source Parameters
https://earthquake.usgs.gov/cfusion/hazfaults_2008_search/query_results.cfm 6/6
99.83 S. San Andreas;BB+NM+SM CA n/a 90 V strike
slip 0 14 184
99.83 S. San Andreas;PK+CH+CC+BB+NM+SM CA n/a 90 V strike
slip 0.1 13 342
99.83 S. San Andreas;SM CA 29 90 V strike
slip 0 13 98
99.83 S. San Andreas;NM+SM CA n/a 90 V strike
slip 0 14 134
1/16/24, 6:02 PM U.S. Seismic Design Maps
https://www.seismicmaps.org 1/3
USGS web services were down for some period of time and as a result this tool wasn't operational, resulting in timeout error.
USGS web services are now operational so this tool should work as expected.
Latitude, Longitude: 33.486678, -117.131289
Date 1/16/2024, 6:02:01 PM
Design Code Reference Document ASCE7-16
Risk Category II
Site Class D - Default (See Section 11.4.3)
Type Value Description
SS 1.595 MCER ground motion. (for 0.2 second period)
S1 0.593 MCER ground motion. (for 1.0s period)
SMS 1.914 Site-modified spectral acceleration value
SM1 null -See Section 11.4.8 Site-modified spectral acceleration value
SDS 1.276 Numeric seismic design value at 0.2 second SA
SD1 null -See Section 11.4.8 Numeric seismic design value at 1.0 second SA
Type Value Description
SDC null -See Section 11.4.8 Seismic design category
Fa 1.2 Site amplification factor at 0.2 second
Fv null -See Section 11.4.8 Site amplification factor at 1.0 second
PGA 0.717 MCEG peak ground acceleration
FPGA 1.2 Site amplification factor at PGA
PGAM 0.861 Site modified peak ground acceleration
TL 8 Long-period transition period in seconds
SsRT 1.595 Probabilistic risk-targeted ground motion. (0.2 second)
SsUH 1.79 Factored uniform-hazard (2% probability of exceedance in 50 years) spectral acceleration
SsD 2.45 Factored deterministic acceleration value. (0.2 second)
S1RT 0.593 Probabilistic risk-targeted ground motion. (1.0 second)
S1UH 0.662 Factored uniform-hazard (2% probability of exceedance in 50 years) spectral acceleration.
S1D 0.977 Factored deterministic acceleration value. (1.0 second)
PGAd 1.032 Factored deterministic acceleration value. (Peak Ground Acceleration)
PGAUH 0.717 Uniform-hazard (2% probability of exceedance in 50 years) Peak Ground Acceleration
CRS 0.891 Mapped value of the risk coefficient at short periods
1/16/24, 6:02 PM U.S. Seismic Design Maps
https://www.seismicmaps.org 2/3
Type Value Description
CR1 0.896 Mapped value of the risk coefficient at a period of 1 s
CV 1.419 Vertical coefficient
1/16/24, 6:02 PM U.S. Seismic Design Maps
https://www.seismicmaps.org 3/3
DISCLAIMER
While the information presented on this website is believed to be correct, SEAOC /OSHPD and its sponsors and contributors assume no responsibility or
liability for its accuracy. The material presented in this web application should not be used or relied upon for any specific application without competent examination
and verification of its accuracy, suitability and applicability by engineers or other licensed professionals. SEAOC / OSHPD do not intend that the use of this
information replace the sound judgment of such competent professionals, having experience and knowledge in the field of practice, nor to substitute for the
standard of care required of such professionals in interpreting and applying the results of the seismic data provided by this website. Users of the information from
this website assume all liability arising from such use. Use of the output of this website does not imply approval by the governing building code bodies responsible
for building code approval and interpretation for the building site described by latitude/longitude location in the search results of this website.
APPENDIX E GENERAL EARTHWORK AND GRADING SPECIFICATIONS
First Ascent Geotechnical Engineering
General Earthwork and Grading Specifications
General
Intent: These General Earthwork and Grading Specifications are intended to
be the minimum requirements for the grading and earthwork shown on the
approved grading plan(s) and/or indicated in the geotechnical report(s).
These General Earthwork and Grading Specifications should be co nsidered a
part of the recommendations contained in the geotechnical repor t(s) and if
they are in conflict with the geotechnical report(s), the specific
recommendations in the geotechnical report shall supersede these more
general specifications. Observations made during earthwork ope rations by
the project Geotechnical Consultant may result in new or revise d
recommendations that may supersede these specifications and/or the
recommendations in the geotechnical report(s).
The Geotechnical Consultant of Record: The Owner shall contract the
Geotechnical Consultant of Record (Geotechnical Consultant) for observation and testing services, prior to commencement of grading or
construction. The Geotechnical Consultant shall be responsible for
reviewing the approved geotechnical report(s) and accepting the
adequacy of the preliminary geotechnical findings, conclusions, and
recommendations prior to the commencement of the grading or
construction.
Prior to commencement of grading or construction, the Owner shall
coordinate with the Geotechnical Consultant, and Earthwork Contractor
(Contractor) to schedule qualified personnel for the appropriate level of
observation, mapping, and compaction testing.
During earthwork and grading operations, the Geotechnical Consultant shall
observe, map, and document the subsurface conditions to
confirm assumptions made during the geotechnical design phase of the project.
Should the observed conditions differ significantly from the interpretive
assumptions made during the design phase, the Geotechnical Consultant shall
recommend appropriate changes to accommodate the observed conditions,
and notify the reviewing agency where required.
The Geotechnical Consultant shall observe the moisture conditioning and
processing of the excavations and fill materials. The Geotechnical Consultant
should perform periodic relative density testing of fill materials to verify that
the attained level of compaction is being accomplished as specified.
The Earthwork Contractor: The Grading Contractor (Contractor) shall be
qualified, experienced, and knowledgeable in earthwork logistics, preparation
and processing of earth materials to receive compacted fill, moisture‐
conditioning and processing of fill, and compacting fill. The Contractor shall be
provided with the approved grading plans and geotechnical report(s) for his
review and acceptance of responsibilities, prior to commencement of grading.
The Contractor shall be solely responsible for performing the grading in
accordance with the approved grading plans and geotechnical report(s) recommendations. The Contractor shall inform the Owner and the
Geotechnical Consultant of work schedule changes and revisions to the work
plan at least 24 hours in advance of such changes so that appropriate
personnel will be available for observation and testing. No assumptions shall
be made by the Contractor with regard to whether the Geotechnical
Consultant is aware of all grading operations.
It is the sole responsibility of the Contractor to provide adequate equipment
and methods to accomplish the earthwork operations in accordance with the
applicable grading codes and agency ordinances, these specifications, and the
recommendations in the approved geotechnical report(s) and grading plan(s).
At the sole discretion of the Geotechnical Consultant, any unsatisfactory
conditions, such as unsuitable earth materials, improper moisture
conditioning, inadequate compaction, insufficient buttress keyway
size, adverse weather conditions, etc., resulting in a quality of work less
than required in the approved grading plans and geotechnical
report(s), the Geotechnical Consultant shall reject the work and may
recommend to the Owner that grading be stopped until conditions are
corrected.
Preparation of Areas for Compacted Fill
Clearing and Grubbing: Vegetation, such as brush, grass, roots, and other
deleterious material shall be sufficiently removed and properly disposed in a
method acceptable to the Owner, Geotechnical Consultant, and governing
agencies.
The Geotechnical Consultant shall evaluate the extent of these removals on a
site by site basis. Earth materials to be placed as compacted fill shall not
contain more than 1 percent organic materials (by volume). No compacted fill
lift shall contain more than 10 percent organic matter.
Should potentially hazardous materials be encountered, the Contractor shall
stop work in the affected area, and a hazardous materials specialist shall
immediately be consulted to evaluate the potentially hazardous materials,
prior to continuing to work in that area.
It is our understanding that the State of California defines most refined
petroleum products (gasoline, diesel fuel, motor oil, grease, c oolant, etc.) as
hazardous waste. As such, indiscriminate dumping or spillage o f these fluids
may constitute a misdemeanor, punishable by fines and/or impris onment, and
shall be prohibited. The contractor is responsible for all haz ardous waste
related to his operations. The Geotechnical Consultant does not have expertise
in this area. If hazardous waste is a concern, then the Owner should contract
the services of a qualified environmental assessor.
Processing: Exposed earth materials that have been observed to be
satisfactory for support of compacted fill by the Geotechnical Consultant shall
be scarified to a minimum depth of 6 inches. Exposed earth materials that are
not observed to be satisfactory shall be removed or alternative
recommendations may be provided by the Geotechnical Consultant.
Scarification shall continue until the exposed earth materials are broken down
and free of oversize material and the working surface is reasonably uniform,
flat, and free of uneven features that would inhibit uniform co mpaction. The
earth materials should be moistened or air dried to near optimu m moisture
content, prior to compaction.
Overexcavation: The Cut Lot Typical Detail and Cut/Fill Transition Lot
Typical Detail, included herein p rovides a graphic illustration that depicts
typical overexcavation recommendations made in the approved geotechnical
report(s) and/or grading plan(s).
Keyways and Benching: Where fills are to be placed on slopes steeper than
5:1 (horizontal to vertical units), the ground shall be thoroughly benched as
compacted fill is placed. Please see the three Keyway and Benc hing Typical
Details with subtitles Cut Over Fill Slope, Fill Over Cut Slope , and Fill Slope for
a graphic illustration. The lowest bench or smallest keyway shall be
a minimum of 10 feet wide (or ½ the proposed slope height) and at least 2
feet into competent earth materials as advised by the Geotechnical
Consultant. Typical benches shall be excavated a minimum height of 4 feet into
competent earth materials or as recommended by the Geotechnical
Consultant. Fill placed on slopes steeper than 5:1 should be thoroughly
benched or otherwise excavated to provide a flat subgrade for the compacted
fill.
Evaluation/Acceptance of Bottom Excavations: All areas to receive
compacted fill (bottom excavations), including removal excavations, processed
areas, keyways, and benching, shall be observed, mapped, general elevations
recorded, and/or tested prior to being accepted by the Geotechnical
Consultant as suitable to receive compacted fill. The Contractor shall obtain
a written acceptance from the Geotechnical Consultant prior to
placing compacted fill. A licensed surveyor shall provide the survey
control for determining elevations of bottom excavations, processed areas,
keyways, and
Fill Materials
benching. The Geotechnical Consultant is not responsible for erroneously
located, fills, subdrain systems, or excavations.
General: Earth material to be used as compacted fill should to a large extent
be free of organic matter and other deleterious substances as e valuated and
accepted by the Geotechnical Consultant.
Oversize: Oversize material is rock that does not break down into smaller
pieces and has a maximum diameter greater than 12 inches. Oversize rock shall
not be included within compacted fill unless specific methods and guidelines
acceptable to the Geotechnical Consultant are followed. For ex amples of
methods and guidelines of oversize rock placement see the enclosed Oversize
Rock Disposal Detail. The inclusion of oversize materials in the compacted fill
shall only be acceptable if the oversize material is completely surrounded by
compacted fill or thoroughly jetted granular materials. No oversize material
shall be placed within 10 vertical feet of finish grade or within 2 feet of
proposed utilities or underground improvements.
Import: Should imported earth materials be required, the proposed imp ort
materials shall meet the requirements of the Geotechnical Consultant. Well
graded, very low expansion potential earth materials free of organic matter
and other deleterious substances are usually sought after as im port materials.
However, it is generally in the Owners best interest that potential import earth
materials are provided to the Geotechnical Consultant to determine their
suitability for the intended purpose. At least 48 hours should be allotted for
the appropriate laboratory testing to be performed, prior to starting the
import operations.
Fill Placement and Compaction Procedures
Fill Layers: Fill materials shall be placed in areas prepared to receive fill in
nearly horizontal layers not exceeding 8 inches in thickness. Thicker layers
may be accepted by the Geotechnical Consultant, provided appropriate machinery is utilized and field density testing indicates that the grading
procedures can adequately compact the thicker layers. Each layer of fill shall
be spread evenly and thoroughly mixed to obtain uniformity within the
earth materials and consistent moisture throughout the fill.
Moisture Conditioning of Fill: Earth materials to be placed as compacted fill
shall be watered, dried, blended, and/or mixed, as needed to obtain relatively
uniform moisture contents that are at or slightly above optimum . The
maximum density and optimum moisture content tests should be pe rformed
in accordance with the American Society of Testing and Material s (ASTM test
method D1557‐00).
Compaction of Fill: After each layer has been moisture‐conditioned, mixed,
and evenly spread, it should be uniformly compacted to a minimum of
90 percent of maximum dry density as determined by ASTM test method
D1557. Compaction equipment shall be adequately sized and be either
specifically designed for compaction of earth materials or be p roven to
consistently achieve the required level of compaction.
Compaction of Fill Slopes: In addition to normal compaction procedures
specified above, additional effort to obtain compaction on slopes is needed.
This may be accomplished by backrolling of slopes with sheepsfoot rollers as
the fill is being placed, by overbuilding the fill slopes, or by other methods
producing results that are satisfactory to the Geotechnical Con sultant. Upon
completion of grading, relative compaction of the fill and the slope face shall be
a minimum of 90 percent of maximum density per ASTM test method D1557‐
00.
Compaction Testing of Fill: Field tests for moisture content and relative
density of the compacted fill earth materials shall be periodically performed by
the Geotechnical Consultant. The location and frequency of tests shall be at the
Geotechnical Consultant's discretion based on field observations. Compaction
test locations will not necessarily be random. The test locations may or may
not be selected to verify minimu m compaction requirements in areas that are
typically prone to inadequate compaction, such as close to slope faces and near
benching.
Frequency of Compaction Testing: Compaction tests shall be taken at
minimum intervals of every 2 vertical feet and/or per 1,000 cubic yards of
compacted materials placed. Additionally, as a guideline, at least one (1) test
shall be taken on slope faces for each 5,000 square feet of slo pe face and/or for
each 10 vertical feet of slope. The Contractor shall assure that fill placement is
such that the testing schedule described herein can be accomplished by the
Geotechnical Consultant. The Contractor shall stop or slow dow n the
earthwork operations to a safe level so that these minimum standards can be
obtained.
Compaction Test Locations: The approximate elevation and horizontal
coordinates of each test location shall be documented by the Geotechnical
Consultant. The Contractor shall coordinate with the Surveyor to assure that
sufficient grade stakes are established. This will provide the Geotechnical
Consultant with sufficient accuracy to determine the approximate test
locations and elevations. The Geotechnical Consultant can not be responsible
for staking erroneously located by the Surveyor or Contractor. A minimum of
two grade stakes should be provided at a maximum horizontal dis tance of 100
feet and vertical difference of less than 5 feet.
Subdrain System Installation
Subdrain systems shall be installed in accordance with the approved geotechnical
report(s), the approved grading plan, and the typical details provided herein. The
Geotechnical Consultant may recommend additional subdrain systems and/or
changes to the subdrain systems described herein, with regard t o the extent, location,
grade, or material depending on conditions encountered during grading or other
factors. All subdrain systems shall be surveyed by a licensed land surveyor (except
for retaining wall subdrain systems) to verify line and grade a fter installation and
prior to burial. Adequate time should be allowed by the Contractor to complete these
surveys.
Excavation
All excavations and over‐excavations for remedial purposes sha ll be evaluated by the
Geotechnical Consultant during grading operations. Remedial removal depths
indicated on the geotechnical plans are estimates only. The actual removal depths
and extent shall be determined by the Geotechnical Consultant based on the field
evaluation of exposed conditions during grading operations. Where fill over cut
slopes are planned, the cut portion of the slope shall be excavated, evaluated, and
accepted by the Geotechnical Consultant prior to placement of t he fill portion of the
proposed slope, unless specifically addressed by the Geotechnic al Consultant. Typical
details for cut over fill slopes and fill over cut slopes are provided herein.
Trench Backfill
1)The Contractor shall follow all OHSA and Cal/OSHA requirements for trench
excavation safety.
2)Bedding and backfill of utility trenches shall be done in accordance with the
applicable provisions in the Standard Specifications of Public Works
Construction. Bedding materials shall have a Sand Equivalency more than 30
(SE>30). The bedding shall be placed to 1 foot over the conduit and
thoroughly jetting to provide densification. Backfill should be compacted to a
minimum of 90 percent of maximum dry density, from 1 foot above the top of
the conduit to the surface.
3)Jetting of the bedding materials around the conduits shall be observed by the
Geotechnical Consultant.
4)The Geotechnical Consultant shall test trench backfill for the minimum
compaction requirements recommen ded herein. At least one test should be
conducted for every 300 linear feet of trench and for each 2 ve rtical feet of
backfill.
5)For trench backfill the lift thicknesses shall not exceed thos e allowed in the
Standard Specifications of Public Works Construction, unless th e Contractor
can demonstrate to the Geotechnical Consultant that the fill lift can be
compacted to the minimum relative compaction by his alternative equipment
or method.
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Geotechnical Map - Plate 1
Mr. Dan Locke Proposed Additions and Additional Dwelling Unit 30130 Cabrillo Avenue Riverside County, California APN 922-140-015 Project No. 23009-10A Not to Scale Date: January 2024 Base Map: Prepared by Wine Country Consulting
B-1
T.D. 8’
First Ascent
Geotechnical Engineering
Geotechnical Map – Plate 1
LEGEND Approximate location of Exploratory Borings – Removal Depths –
GEOLOGIC UNITS Qyv – Quaternary Young Alluvium Valley Deposits Elsinore Fault Zone Limits -
B-2
T.D. 5’
Qyv
-3’
Elsinore Fault Zone Limits
-3’
Qyv
-3’