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Home My WebLink AboutPA2023-0137_20230726_Geotech Report dated 07-24-23 LIMITED GEOTECHNICAL INVESTIGATION PROPOSED NEW ROOM ADDITION AND A GARAGE EXTENSION 1812 GALAXY DRIVE, NEWPORT BEACH, CALIFORNIA MR. CRAIG MACOMBER July 24, 2023 J.N. 23-234 ENGINEERS + GEOLOGISTS + ENVIRONMENTAL SCIENTISTS Offices Strategically Positioned Throughout Southern California ORANGE COUNTY OFFICE 3186 Airway Avenue, Suite K, Costa Mesa, California 92626 T: 714.549.8921 F: 714.668-3770 For more information visit us online at www.petra-inc.com July 24, 2023 J.N. 23-234 MR. CRAIG MACOMBER 1812 Galaxy Drive Newport Beach, California 92672 Subject: Limited Geotechnical Investigation, Room Addition and a Garage Extension, 1812 Galaxy Drive, Newport Beach, California Dear Mr. Macomber: Petra Geosciences, Inc. (Petra) is submitting herein is our limited geotechnical investigation report for the property located at 1812 Galaxy Drive in the city of Newport Beach, California. This work was performed in accordance with the scope of work outlined in our Proposal No. 23-234P, dated June 6, 2023. This report presents the results of our field investigation, laboratory testing, and our engineering judgment, opinions, conclusions, and recommendations pertaining to the geotechnical design aspects of the proposed development. We appreciate the opportunity to be of service to you on this project. If you have any questions regarding the contents of this report, or should you require additional information, please contact the undersigned at (949) 633-7765. Respectfully submitted, PETRA GEOSCIENCES, INC. Evan Price Associate Geologist MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 TABLE OF CONTENTS Page INTRODUCTION ......................................................................................................................................................... 1 SITE LOCATION AND DESCRIPTION ..................................................................................................................... 1 PROPOSED CONSTRUCTION AND GRADING ...................................................................................................... 1 Proposed Construction ....................................................................................................................................... 1 Proposed Grading ............................................................................................................................................... 1 SITE RECONNAISSANCE AND SUBSURFACE EXPLORATION ......................................................................... 2 LABORATORY TESTING .......................................................................................................................................... 2 FINDINGS .................................................................................................................................................................... 3 Background Information .................................................................................................................................... 3 Regional Geology............................................................................................................................................... 3 Local Geology and Subsurface Conditions ........................................................................................................ 3 Groundwater ....................................................................................................................................................... 4 Faulting .............................................................................................................................................................. 4 Seismic Hazard Zones ........................................................................................................................................ 5 Seismically Induced Flooding ............................................................................................................................ 5 CONCLUSIONS AND RECOMMENDATIONS ........................................................................................................ 5 General ..................................................................................................................................................................... 5 Grading Plan Review ............................................................................................................................................... 6 Site/Slope Stability .................................................................................................................................................. 6 Effect of Proposed Grading on Adjacent Properties ................................................................................................ 6 Primary Geotechnical ConcernS .................................................................................................................................... 6 Existing Undocumented Fill and Unsuitable Soils ............................................................................................. 6 Earthwork ................................................................................................................................................................ 7 General Earthwork and Grading Specifications ................................................................................................. 7 Site Clearing ....................................................................................................................................................... 7 Contaminant-Affected Soils ............................................................................................................................... 7 Ground Preparation ............................................................................................................................................ 7 Fill Placement and Testing ................................................................................................................................. 8 Excavation Characteristics ................................................................................................................................. 8 Stability of Temporary Excavation Sidewalls .................................................................................................... 9 Monitoring of Adjacent Properties ..................................................................................................................... 9 Geotechnical Observations ............................................................................................................................... 10 Post-Grading Considerations ................................................................................................................................. 10 Site Drainage .................................................................................................................................................... 10 Bottomless Trench Drains ................................................................................................................................ 11 Utility Trench Backfill ..................................................................................................................................... 11 Slope Landscaping and Maintenance ............................................................................................................... 12 Foundation Design Guidelines ............................................................................................................................... 12 Near-Fault Site Determination ......................................................................................................................... 12 Seismic Design Parameters .............................................................................................................................. 12 Discussion - General ........................................................................................................................................ 15 Allowable Bearing Capacity, Estimated Settlement and Lateral Resistance ......................................................... 16 Existing Footings ............................................................................................................................................. 16 Allowable Soil Bearing Capacities................................................................................................................... 16 Estimated Footing Settlement .......................................................................................................................... 17 Lateral Resistance ............................................................................................................................................ 17 Guidelines for Footings and Slabs on-Grade Design and Construction ................................................................. 17 Conventional Slabs on-Grade System .............................................................................................................. 18 Foundation Observations ....................................................................................................................................... 20 General Corrosivity Screening ............................................................................................................................... 21 Masonry Block Walls ............................................................................................................................................ 22 MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 TABLE OF CONTENTS Page Construction on Level Ground (Front Yard) .................................................................................................... 22 Planter Walls .......................................................................................................................................................... 22 Exterior Concrete Flatwork .................................................................................................................................... 23 General ............................................................................................................................................................. 23 Thickness and Joint Spacing ............................................................................................................................ 23 Reinforcement .................................................................................................................................................. 23 Edge Beams (Optional) .................................................................................................................................... 23 Subgrade Preparation ....................................................................................................................................... 24 Drainage ........................................................................................................................................................... 24 Tree Wells ........................................................................................................................................................ 24 Construction Along Top of Adjacent Descending Slope ................................................................................. 25 FUTURE IMPROVEMENTS ..................................................................................................................................... 25 REPORT LIMITATIONS ........................................................................................................................................... 25 REFERENCES ............................................................................................................................................................ 27 ATTACHMENTS FIGURE 1 SITE LOCATION MAP FIGURE 2 GEOTECHNICAL MAP APPENDIX A EXPLORATION LOGS APPENDIX B LABORATORY TEST PROCEDURES / LABORATORY DATA SUMMARY APPENDIX C SEISMIC DESIGN ANALYSIS LIMITED GEOTECHNICAL INVESTIGATION PROPOSED ROOM ADDITION AND GARAGE EXTENSION 1812 GALAXY DRIVE, NEWPORT BEACH, CALIFORNIA INTRODUCTION Petra Geosciences, Inc. (Petra) is presenting herein the results of our limited geotechnical investigation of the subject property. The purposes of this investigation were to determine the nature of the surface and subsurface soils, to evaluate their in-place characteristics, and to provide geotechnical recommendations with respect to site clearing and grading, and for the design and construction of new building foundations and other site improvements. The subsurface investigation, laboratory testing, conclusions, and recommendations presented herein are limited the improvements described below to be located in the front yard portion of the site. Our scope of services did not include geotechnical investigation within the rear yard of the property and did not include evaluation or stability analysis of the bluff slope descending from the rear yard of the property. Therefore, this report does not contain adequate information for use in the design and construction of any improvements in the back yard of the site and provides no opinions, recommendations, or conclusions regarding the stability of the back yard descending slope. SITE LOCATION AND DESCRIPTION The subject property is located at 1812 Galaxy Drive in the city of Newport Beach, California (see Figure 1). The roughly rectangular-shaped property is currently the site of a one-story, single-family residence with an attached 2-car garage. Other improvements include a rear yard pool, spa, and associated flatwork. The property is bounded on the northeast and southwest by existing single-family residences, on the northwest by Galaxy Drive, and on the southeast by an approximately 85 foot high, roughly 1.25:1 (horizontal to vertical), northeast-southwest trending bluff that descends to the Upper Newport Bay. PROPOSED CONSTRUCTION AND GRADING Proposed Construction Based on our review of the architectural plans prepared by Graphic Impact, dated January 26, 2023, for the subject project, it is our understanding that the proposed construction will consist of a one-story bedroom addition to the northwestern portion of the single family-residence and an extension to the existing two-car garage. It is expected that the proposed additions will be of wood-frame construction and will be supported on conventional foundations (i.e., concrete spread or pad footings). No subterranean levels are currently anticipated. Proposed Grading Based on the information presented on the architectural plans, the proposed building will be constructed at essentially the same grades as the existing structure. Based on this condition, cuts and fills of generally a foot or less are anticipated to achieve final design grades. It should be noted, however, that the ultimate fill MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 2 thicknesses throughout the site will be greater due to the required remedial grading (i.e., removal and recompaction of existing unsuitable surficial soils) as recommended in subsequent sections of this report. Recommendations for site grading, and for the design and construction of building foundations, are presented in the “Conclusions and Recommendations” section of this report. SITE RECONNAISSANCE AND SUBSURFACE EXPLORATION A site reconnaissance and subsurface exploration were performed on June 13, 2023. The site reconnaissance consisted of a visual evaluation of the existing surface conditions of the site as described in the “Site Location and Description” section of this report. Our subsurface exploration consisted of the advancement of two hand-augured exploratory borings (HA-1 and HA-2) to depths ranging from approximately 12 to 5.5 feet below the ground surface, respectively. The purpose of the subsurface exploration was to assess the quality of the near-surface earth materials and to determine the depth of existing fill. The soil materials encountered were visually classified and logged in general accordance with the visual-manual guidelines associated with the Unified Soil Classification System. The approximate locations of the borings are shown on the enclosed Geotechnical Map (Figure 2), and descriptive exploration logs are presented in Appendix A. Associated with our subsurface exploration was the collection of bulk and relatively undisturbed samples of soil materials for laboratory testing. The relatively undisturbed samples were obtained at various depths using a 3-inch outside diameter, modified California split-spoon sampler lined with 1-inch brass ring liners that was driven into the ground by repetitive drops of a hand operated drop hammer. The central portions of the driven core samples were placed in sealed containers and transported to our laboratory for testing. LABORATORY TESTING To evaluate the engineering properties of the soils underlying the subject site, several laboratory tests were performed on selected samples considered representative of the materials encountered. Laboratory tests included the determination of in-situ dry unit weight and moisture content, laboratory maximum dry density and optimum moisture content, expansion potential, Atterberg Limits, soluble sulfate and chloride content, pH, minimum resistivity, and shear strength analyses. A description of laboratory test procedures and a summary of the laboratory test results are provided in Appendix B and in our “Exploration Logs”, Appendix A. An evaluation of the test data is reflected throughout the “Conclusions and Recommendations” section of this report. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 3 FINDINGS Background Information A search of the website of the City of Newport Beach Building Department’s archived permit history revealed the construction of the original residence was performed in 1965 under Lot 32 of Tract No. 4224. As-Built Grading plans prepared by Boyle Engineering for Tract 4224, dated January 26, 1965 indicate that the site had a 2-foot think fill blanket and indicated no other changes to the original topography in the vicinity of the subject property. Permits for additions and remodels were pulled for the subject property in 1981, 1982, 1993, 1994, 1995 and 1998. Regional Geology Based on our review of published geologic references, the area of the subject site is located on an elevated coastal marine terrace deposits at the southern end of the Los Angeles Basin within the Peninsular Ranges Geomorphic Province. This elevated terrace is characterized by an upper surface that slopes very gently from the inland hills southwest to the sea cliffs along the Pacific Coast. The local geology is characterized by old marine deposits (terrace deposits), which were deposited on the now emergent wave cut abrasion platforms preserved by regional uplift. Regional geologic maps indicate that the subject site and surrounding properties are underlain by very old paralic deposits. The soil materials are reported to consist of silt, sand, and cobbles on emergent wave-cut abrasion platforms. Although not encountered in our investigation, the regional geologic map (Morton, 2004) indicate that the bedrock in the vicinity of the site is derived from the Capistrano Formation and dips generally in a northeasterly direction at an angle of 15 degrees. Local Geology and Subsurface Conditions Undocumented fill materials (map symbol afu) were encountered within our hand-augured exploratory borings to approximate depths of 3 to 4 feet below the existing ground surface. The undocumented fills consisted of a mantle of fine grained sandy clay over medium- to coarse-grained sand with abundant shell fragments that were likely derived from the Newport bay dredging operations. Very old paralic deposits (map symbol Qvop) were encountered in both borings HA-1 and HA-2 to the maximum depth explored (approximately 12 feet). These materials were observed to consist of fine-grained sandy clay that was olive gray to gray, moist, and stiff. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 4 Although not encountered during our subsurface exploration, regional geologic maps indicate that the site is underlain at depth by bedrock materials of the Capistrano Formation. Bedrock materials are reported to consist of very stiff to hard, massive to crudely bedded, siltstones and mudstone. Regional geologic maps (Morton and Miller, 1981) indicate that the bedrock materials in the vicinity of the site dip 15 degrees generally in a north-easterly direction. Groundwater No groundwater was encountered within our exploratory borings to the maximum depth explored (approximately 12 feet). Furthermore, published literature indicates that the depth to historically high groundwater in the area of the subject site is generally considered to be greater than 30 feet below the surface (CDMG, 2001). Faulting Based on our review of the referenced geologic maps and literature, no active faults are known to project through the property. Furthermore, the site does not lie within the boundaries of an “Earthquake Fault Zone” as defined by the State of California in the Alquist-Priolo Earthquake Fault Zoning Act (CGS, 2018). The Alquist-Priolo Earthquake Fault Zoning Act (AP Act) defines an active fault as one that “has had surface displacement within Holocene time (about the last 11,000 years).” The main objective of the AP Act is to prevent the construction of dwellings on top of active faults that could displace the ground surface resulting in loss of life and property. According to the 2014 USGS PSHA (probabilistic seismic hazard assessment) Interactive Deaggregation web site tool and/or the 2010 CGS ‘Fault Activity Map of California’, the subject site is located approximately 4.8 kilometers (2.9 miles) northeast of the Newport-Inglewood fault zone. The Newport- Inglewood fault consists of a series of parallel and en-echelon, northwest-trending faults and folds extending from the southern edge of the Santa Monica Mountains southeast to the offshore area of south Orange County. This zone has a history of moderate to high seismic activity and has generated several historic earthquakes greater than magnitude 4.0, including the March 11, 1933 Long Beach earthquake (magnitude 6.3), the October 21, 1941 earthquake (magnitude 4.9), and the June 18, 1944 earthquake (magnitude 4.5). In addition, the San Joaquin Hills Blind Thrust Fault (SJHBTF) is believed to underlie the San Joaquin Hills (Grant, et al, 1999) and was incorporated into the State of California probabilistic seismic hazard database by the California Geological Survey (Cao, et al. 2003). Although the San Joaquin Hills thrust has MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 5 not been observed directly at the surface, structural modeling indicates that this fault has a slip rate of approximately 0.5 millimeter per year and a recurrence interval of approximately 1,650 to 3,100 years for moderate-sized earthquakes. Recent blind thrust earthquakes, including the 1987 magnitude 5.9 Whittier Narrows and the 1994 magnitude 6.7 Northridge events, have demonstrated the significance of these features with respect to the tectonic setting of southern California. Seismic Hazard Zones Through the Seismic Hazards Mapping Act, the California Geological Survey (formerly the California Division of Mines and Geology) has established Seismic Hazard Zones for the more densely populated areas of southern and northern California. According to the Seismic Hazard Zone map for the Newport 7.5- minute quadrangle (CDMG, 1998), the location of the subject improvements are not located within an area that has been mapped as being potentially susceptible to either earthquake-induced liquefaction or landsliding. Based on our subsurface exploration and geologic study, we concur that the site is not susceptible to either earthquake-induced liquefaction or landsliding. Seismically Induced Flooding The types of seismically induced flooding that are generally considered as potential hazards to a particular site normally include flooding due to a tsunami (seismic sea wave), a seiche, or failure of a major reservoir or other water retention structure upstream of the site. Since the site lies at an estimated elevation of approximately 85 to 88 feet MSL (based on a review of Google Earth and the topographic map of the Newport Beach Quadrangle produced by the United States Geological Survey, USGS), and lies roughly 85 feet above the adjacent Upper Newport bay, and does not lie downstream of a major reservoir retention structure, the probability of flooding from a tsunami, seiche, or dam-break inundation is considered non- existent. Additionally, the site is not located within a Tsunami Inundation Area on the Tsunami Inundation Map for Emergency Planning, produced by the State of California (2019). CONCLUSIONS AND RECOMMENDATIONS General From a soils engineering and engineering geologic point of view, the subject property is considered suitable for the proposed construction provided the following conclusions and recommendations are incorporated into the design criteria and project specifications. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 6 Grading Plan Review Although a grading plan is not yet available for review, it is expected that the proposed addition will be constructed at essentially the same elevations as existing ground surface elevations; therefore, only minor cuts and fills would be anticipated to be achieve proposed finish grades. However, additional fill will be created as a result of the remedial overexcavation and recompaction of near-surface soils recommended herein. Recommendations for site grading and for the design and construction of building foundations are presented later in this report. Site/Slope Stability The proposed improvements are located in the front portion of the existing residence, near where the property borders Galaxy Drive. An approximately 85 feet high, roughly 1.25:1 (horizontal to vertical), northeast-southwest facing slope descends from the rear yard of the subject property. This slope exhibits a moderate cover of natural vegetation. No previous evidence or documentation of gross or surficial instability at the site was found during our background review. No additions or improvements are proposed within the rear yard area adjacent to this slope. Given the location of the proposed improvements, the gross and surficial instability of the rear yard slope are not considered to impact the proposed improvements. Effect of Proposed Grading on Adjacent Properties It is our opinion that the proposed grading and construction will not adversely affect the stability of adjoining properties provided that grading and construction are performed in accordance with the recommendations presented herein. PRIMARY GEOTECHNICAL CONCERNS Existing Undocumented Fill and Unsuitable Soils The existing undocumented fill an approximate depth of 3 to 4 feet are not suitable as a bearing media for new fill or structure foundations. In addition, it is expected that existing surficial soils will be disturbed during the demolition of the existing improvements. Therefore, the existing undocumented fill and any unsuitable native soils will require complete removal to competent very old parlic deposits prior to re- placement as engineered fill to design grade. Recommendations for remedial grading and for design and construction of foundations are provided in the “Earthwork” and “Foundation Design Guidelines” sections of this report. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 7 Earthwork General Earthwork and Grading Specifications All earthwork and grading should be performed in accordance with Chapter 15 of the Municipal Code of the City of Newport Beach, the 2022 California Building Code (CBC), and in accordance with the following recommendations prepared by this firm. Site Clearing Clearing operations should include the removal of all landscape vegetation and existing structural features to be demolished, such as footings, retaining walls, concrete sidewalks and driveways. Trees and large shrubs, when removed, should be grubbed out to include their stumps and major root systems. Existing underground utilities lines located in areas of proposed grading should also be removed and the resultant excavations backfilled with engineered fill. Should any unusual soil conditions or subsurface structures be encountered during grading, they should be brought to the immediate attention of the project geotechnical consultant for corrective recommendations. Contaminant-Affected Soils If hydrocarbon-affected soils or soils affected by potentially hazardous materials are encountered during grading, it is recommended that the earthwork within the affected area be terminated pending further evaluation by the project environmental consultant. Ground Preparation Existing fill materials to depths of approximately 3 to 4 feet are subject to compression under the anticipated footing loads. Therefore, in order to provide suitable and relatively uniform support for the proposed structural foundations and exterior site improvements and reduce the potential for differential settlement, it is recommended that the fill be over-excavated to expose competent very old paralic deposits, or to a depth of 1 foot below the bottoms of proposed structural footings, whichever is deeper, and the excavated material replaced as engineered fill. It is possible that localized areas may be encountered where low-density soils extend to depths in excess of 3 to 4 feet below the surface. Where such materials are encountered during grading, deeper remedial excavation will be required to remove all low-density soils and expose competent very old paralic deposits that are suitable for support of new engineered fills and building loads. The actual depth of required MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 8 remedial removals should be determined during grading based on field observations by a representative of this firm Following removal of the unsuitable surficial soils and prior to replacing these soils as engineered fill, the exposed bottom surfaces in each removal area should first be scarified to a depth of 6 inches, watered as necessary to achieve a slightly-above optimum moisture content, and then recompacted to a minimum relative compaction of 90 percent of the applicable laboratory maximum density standard as determined in accordance with the current version of ASTM Test Method No. D 1557. In order to provide adequate support for sidewalks, driveways, and similar perimeter improvements, overexcavation and recompaction of the existing ground should essentially extend to a horizontal distance of approximately 3 feet beyond the proposed construction; however, consideration should be given to the protection of adjacent structures as described in the following section of this report. Further, the bottom of the overexcavation should not encroach within an area behind a projected descending 45-degree angle with the property line, otherwise shoring will be required per City of Newport Beach Policy No. NBMC 15.10.140. In addition, any undocumented fill exposed in the temporary overexcavation backcuts within the footprint of the proposed improvements should also be benched out during fill placement operations. Fill Placement and Testing All fill should be placed in lifts not exceeding 6 inches in thickness, watered or air dried as necessary to achieve at or above optimum moisture conditions, and then compacted in place to a minimum relative compaction of 90 percent of the applicable laboratory maximum dry density in accordance with ASTM Test Method D 1557. Each fill lift should be treated in a similar manner. Imported soils, if any, should consist of clean granular materials exhibiting a Very Low expansion potential (Expansion Index between 0 and 20) and be free of deleterious materials, oversize rock and any organic materials. Soils to be imported should be approved by the project geotechnical consultant prior to importation. Excavation Characteristics Based on the results of our subsurface investigation, all soils within the site are expected to be readily excavatable with conventional earthmoving equipment. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 9 Stability of Temporary Excavation Sidewalls During site remedial grading, temporary excavations with sidewalls of up to approximately 3 to 4 feet in height will be required to overexcavate the existing unsuitable soils. The sidewalls of these temporary excavations are expected to expose approximately 3 to 4 feet of fill materials that overlie very old paralic deposits. Based on the physical characteristics of the on-site soil materials, temporary slopes of this height, and at least 5 feet away from the property line, may be tentatively planned at a slope gradient no steeper than 1:1 (horizontal to vertical). However, to protect property line structures along the property lines, a 1:1 (horizontal to vertical) cut may be excavated beginning at approximately the existing property line/structures. This 1:1 temporary backcut should be performed in two sections. A representative of the project geotechnical consultant should observe the first section of the temporary backcut to evaluate the necessity for alternate recommendations for removal of the remaining wedge of soil along the property line. Temporary slopes excavated at the above slope configurations are expected to remain stable during construction; however, the temporary excavations should be observed by a representative of the project geotechnical consultant for any evidence of potential instability. Depending on the results of these observations, revised slope configurations may be necessary. Other factors that should be considered with respect to the stability of temporary slopes include construction traffic and storage of materials on or near the tops of the slopes, construction scheduling, presence of nearby walls or structures, and weather conditions at the time of construction. All applicable requirements of the California Construction and General Industry Safety Orders, the Occupational Safety and Health Act of 1970, and the Construction Safety Act should also be followed. No temporary excavations along the property lines should be left open without proper protections to mitigate safety hazards. The grading contractor is solely responsible for ensuring the safety of construction personnel and the general public, and for appointing a designated “Competent Person” to observe and classify temporary excavation sidewalls pursuant to 29 CFR Part 1926 (OSHA Safety and Health Regulations for Construction). Monitoring of Adjacent Properties Existing adjoining residential structures in the immediate vicinity of temporary excavations may have pre- existing damage, which go unnoticed (hairline cracks, etc.) until some construction activity draws attention to such conditions. Then, it becomes difficult to identify whether damage was pre-existing or has been caused by the construction. To help reduce the risk of such conflicts, it is advisable, though not required, to MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 10 perform a pre-construction condition survey of existing structures, especially those located directly along the property lines. This would involve visual inspection and photo and video documentation. The proposed construction is likely to create vibrations in the vicinity of adjoining structures, due to activities such as excavations into hard or dense earth materials. At your discretion, vibrations be monitored on or near existing buildings and structures in order to reduce the risk of damage to existing buildings and defend against potential future claims. Geotechnical Observations Exposed bottom surfaces in each removal/excavation area should be observed and approved by the project geotechnical consultant prior to placing fill. No fills should be placed without prior approval from the geotechnical consultant. The project geotechnical consultant should also be present on site during grading operations to verify proper placement and adequate compaction of fill, as well as to evaluate compliance with the other recommendations presented herein. Post-Grading Considerations Site Drainage Positive drainage devices such as sloped concrete flatwork, graded swales and area drains should be provided around the new construction to collect and direct all water to a suitable discharge area. Neither rain nor excess irrigation water should be allowed to collect or pond against building foundations. The owner is advised that the drainage system should be properly maintained throughout the life of the proposed development. The purpose of this drainage system will be to reduce water infiltration into the subgrade soils and to direct surface water away from building foundations, and walls. The following recommendations should be implemented during construction. 1. Area drains should be extended into all planters and landscape areas that are located within 10 feet of building foundations to reduce excessive infiltration of water into the foundation soils. Per the 2022 CBC, the ground surfaces within all landscape areas located within 10 feet of building foundations should be sloped at a minimum gradient of 5 percent away from the walls and foundations and to the area drains. The ground surfaces of planter and landscape areas that are located more than 10 feet away from building foundations may be sloped at a minimum gradient of 2 percent away from the foundations and towards the nearest area drains. 2. Per the 2022 CBC, concrete flatwork surfaces that are located within 10 feet of building foundations should be inclined at a minimum gradient of 2 percent away from the building foundations and towards the nearest area drains. Concrete flatwork surfaces that are located more than 10 feet away from building foundations may be sloped at a minimum gradient of 1 percent away from the foundations and towards the nearest area drains. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 11 3. A watering program should be implemented for the landscape areas that maintain a uniform, near optimum moisture condition in the soils. Overwatering and subsequent saturation of the soils will cause excessive soil expansion and heave and, therefore, should be avoided. On the other hand, allowing the soils to dry out will cause excessive soil shrinkage. As an alternative to a conventional irrigation system, drip irrigation is strongly recommended for all planter areas. The owner is advised that all drainage devices should be properly maintained throughout the lifetime of the development. Bottomless Trench Drains Infiltration is not recommended for this site. Utility Trench Backfill All utility trench backfill should be compacted to a minimum relative compaction of 90 percent. Onsite soils cannot be densified adequately by flooding and jetting techniques; therefore, trench backfill materials should be placed in lifts no greater than approximately 6 inches in thickness, watered or air dried as necessary to achieve a uniform moisture content that is equal to or slightly above optimum moisture, and then mechanically compacted in-place to a minimum relative compaction of 90 percent. A representative of the project geotechnical consultant should probe and test the backfills to document that adequate compaction has been achieved. For shallow trenches where pipe may be damaged by mechanical compaction equipment, such as under the building floor slab, imported clean sand exhibiting a sand equivalent value (SE) of 30 or greater may be utilized. The sand backfill materials should be watered to achieve near optimum moisture conditions and then tamped in place. No specific relative compaction will be required; however, observation, probing, and, if deemed necessary, testing should be performed by a representative of the project geotechnical consultant to document that the sand backfill is adequately compacted and will not be subject to excessive settlement. Where utility trenches enter the footprint of the building, they should be backfilled through their entire depths with on-site fill materials, sand-cement slurry or concrete rather than with any sand or gravel shading. This “plug” of less- or non-permeable materials will mitigate the potential for water to migrate through the backfilled trenches from outside of the building to the areas beneath the foundations and floor slabs. If clean, imported sand is to be used for backfill of exterior utility trenches, it is recommended that the upper 12 inches of trench backfill materials consist of property compacted on-site soil materials. This is to reduce infiltration of irrigation and rainwater into granular trench backfill materials. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 12 Where an interior or exterior utility trench is proposed parallel to a building footing, the bottom of the trench should not be located below a 1:1 plane projected downward from the outside bottom edge of the adjacent footing. Where this condition exists, the adjacent footing should be deepened such that the bottom of the utility trench is located above the 1:1 projection. Slope Landscaping and Maintenance A permanent slope maintenance program should be initiated that should include the care of deep rooted landscape vegetation, drainage and erosion control provisions, rodent control, and repair of leaking irrigation systems. The owner should be advised that potential problems can develop when drainage on the building pad is allowed to run onto the descending slope. Foundation Design Guidelines Near-Fault Site Determination Based on our review of the referenced geologic maps and literature, no active faults are known to project through the property. Furthermore, the site does not lie within the boundaries of an “Earthquake Fault Zone” as defined by the State of California in the Alquist-Priolo Earthquake Fault Zoning Act (CGS, 2018). The Alquist-Priolo Earthquake Fault Zoning Act (AP Act) defines an active fault as one that “has had surface displacement within Holocene time (about the last 11,000 years).” The main objective of the AP Act is to prevent the construction of dwellings on top of active faults that could displace the ground surface resulting in loss of life and property. However, it should be noted that according to the USGS Unified Hazard Tool website and/or 2010 CGS Fault Activity Map of California, the Newport Inglewood Fault zone, located approximately 2.9 miles southwest of the site, would probably generate the most severe site ground motions and, therefore, is the majority contributor to the deterministic minimum component of the ground motion models. The subject site is located at a distance of less than 8.5 miles (13.6 km) from the surface projection this fault system, which is capable of producing a magnitude 7 or larger events with a slip rate along the fault greater than 0.04 inch per year. As such, the site should be considered as a Near-Fault Site in accordance with ASCE 7-16, Section 11.4.1. Seismic Design Parameters Earthquake loads on earthen structures and buildings are a function of ground acceleration which may be determined from the site-specific ground motion analysis. Alternatively, a design response spectrum can be developed for certain sites based on the code guidelines. To provide the design team with the parameters MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 13 necessary to construct the design acceleration response spectrum for this project, we used two computer applications. Specifically, the first computer application, which was jointly developed by Structural Engineering Association of California (SEAOC) and California’s Office of Statewide Health Planning and Development (OSHPD), the SEA/OSHPD Seismic Design Maps Tool website, https://seismicmaps.org, is used to calculate the ground motion parameters. The second computer application, the United Stated Geological Survey (USGS) Unified Hazard Tool website, https://earthquake.usgs.gov/hazards/interactive/, is used to estimate the earthquake magnitude and the distance to surface projection of the fault. To run the above computer applications, site latitude and longitude, seismic risk category and knowledge of site class are required. The site class definition depends on an evaluation of the average small-strain shear wave velocity, Vs30, within the upper 30 meters (approximately 100 feet) of site soils. A seismic risk category of II was assigned to the proposed building in accordance with 2022 CBC, Table 1604.5. No shear wave velocity measurement was performed at the site, however, the subsurface materials at the site appears to exhibit the characteristics of stiff soils condition for Site Class D designation. Therefore, an average shear wave velocity of 600 to 1,200 feet per second for the upper 100 feet was assigned to the site based on engineering judgment and geophysical experience. As such, in accordance with ASCE 7-16, Table 20.3-1, Site Class D (D- Default as per SEA/OSHPD software) has been assigned to the subject site. The following table, Table 1, provides parameters required to construct the seismic response coefficient, Cs, curve based on ASCE 7-16, Article 12.8 guidelines. A printout of the computer output is attached in Appendix C. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 14 TABLE 1 Seismic Design Parameters Ground Motion Parameters Specific Reference Parameter Value Unit Site Latitude (North) - 33.6367 ° Site Longitude (West) - -117. 8918 ° Site Class Definition Section 1613.2.2 (1), Chapter 20 (2) D-Default (4) - Assumed Seismic Risk Category Table 1604.5 (1) II - Mw - Earthquake Magnitude USGS Unified Hazard Tool (3) 7.5 (3) - R – Distance to Surface Projection of Fault USGS Unified Hazard Tool (3) 4.8 (3) km Ss - Mapped Spectral Response Acceleration Short Period (0.2 second) Figure 1613.2.1(1) (1) 1.342 (4) g S1 - Mapped Spectral Response Acceleration Long Period (1.0 second) Figure 1613.2.1(2) (1) 0.478 (4) g Fa – Short Period (0.2 second) Site Coefficient Table 1613.2.3(1) (1) 1.2 (4) - Fv – Long Period (1.0 second) Site Coefficient Table 1613.2.3(2) (1) Null (4) - SMS – MCER Spectral Response Acceleration Parameter Adjusted for Site Class Effect (0.2 second) Equation 16-36 (1) 1.611 (4) g SM1 - MCER Spectral Response Acceleration Parameter Adjusted for Site Class Effect (1.0 second) Equation 16-37 (1) Null (4) g SDS - Design Spectral Response Acceleration at 0.2-s Equation 16-38 (1) 1.074 (4) g SD1 - Design Spectral Response Acceleration at 1-s Equation 16-39 (1) Null (4) g To = 0.2 SD1/ SDS Section 11.4.6 (2) Null s Ts = SD1/ SDS Section 11.4.6 (2) Null s TL - Long Period Transition Period Figure 22-14 (2) 8 (4) s PGA - Peak Ground Acceleration at MCEG (*) Figure 22-9 (2) 0.582 g FPGA - Site Coefficient Adjusted for Site Class Effect (2) Table 11.8-1 (2) 1.2 (4) - PGAM –Peak Ground Acceleration (2) Adjusted for Site Class Effect Equation 11.8-1 (2) 0.698 (4) g Design PGA ≈ (⅔ PGAM) - Slope Stability (†) Similar to Eqs. 16-38 & 16-39 (2) 0.465 g Design PGA ≈ (0.4 SDS) – Short Retaining Walls (‡) Equation 11.4-5 (2) 0.430 g CRS - Short Period Risk Coefficient Figure 22-18A (2) 0.915 (4) - CR1 - Long Period Risk Coefficient Figure 22-19A (2) 0.924 (4) - SDC - Seismic Design Category (§) Section 1613.2.5 (1) Null (4) - References: (1) California Building Code (CBC), 2022, California Code of Regulations, Title 24, Part 2, Volume I and II. (2) American Society of Civil Engineers/Structural Engineering Institute (ASCE/SEI), 2016, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, Standards 7-16. (3) USGS Unified Hazard Tool - https://earthquake.usgs.gov/hazards/interactive/ (4) SEI/OSHPD Seismic Design Map Application – https://seismicmaps.org Related References: Federal Emergency Management Agency (FEMA), 2015, NEHERP (National Earthquake Hazards Reduction Program) Recommended Seismic Provision for New Building and Other Structures (FEMA P-1050). Notes: * PGA Calculated at the MCE return period of 2475 years (2 percent chance of exceedance in 50 years). † PGA Calculated at the Design Level of ⅔ of MCE; approximately equivalent to a return period of 475 years (10 percent chance of exceedance in 50 years). ‡ PGA Calculated for short, stubby retaining walls with an infinitesimal (zero) fundamental period. § The designation provided herein may be superseded by the structural engineer in accordance with Section 1613.2.5.1, if applicable. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 15 Discussion - General Owing to the characteristics of the subsurface soils, as defined by Site Class D-Default designation, and proximity of the site to the sources of major ground shaking, the site is expected to experience strong ground shaking during its anticipated life span. Under these circumstances, where the code-specified design response spectrum may not adequately characterize site response, the 2022 CBC typically requires a site- specific seismic response analysis to be performed. This requirement is signified/identified by the “null” values that are output using SEA/OSHPD software in determination of short period, but mostly, in determination of long period seismic parameters, see Table 1. For conditions where a “null” value is reported for the site, a variety of design approaches are permitted by 2022 CBC and ASCE 7-16 in lieu of a site-specific seismic hazard analysis. For any specific site, these alternative design approaches, which include Equivalent Lateral Force (ELF) procedure, Modal Response Spectrum Analysis (MRSA) procedure, Linear Response History Analysis (LRHA) procedure and Simplified Design procedure, among other methods, are expected to provide results that may or may not be more economical than those that are obtained if a site-specific seismic hazards analysis is performed. These design approaches and their limitations should be evaluated by the project structural engineer. Discussion – Seismic Design Category Please note that the Seismic Design Category, SDC, is also designated as “null” in Table 1. For conditions where the mapped spectral response acceleration parameter at 1 – second period, S1, is less than 0.75, the 2022 CBC, Section 1613.2.5.1 allows that seismic design category to be determined from Table 1613.2.5(1) alone provided that all 4 requirements concerning fundamental period of structure, story drift, seismic response coefficient, and relative rigidity of the diaphragms are met. Our interpretation of ASCE 7-16 is that for conditions where one or more of these 4 conditions are not met, seismic design category should be assigned based on: 1) 2022 CBC, Table 1613.2.5(1), 2) structure’s risk category and 3) the value of SDS, at the discretion of the project structural engineer. Discussion – Equivalent Lateral Force Method Should the Equivalent Lateral Force (ELF) method be used for seismic design of structural elements, the value of Constant Velocity Domain Transition Period, Ts, is estimated to 0.541 seconds and the value of Long Period Transition Period, TL, is provided in Table 1 for construction of Seismic Response Coefficient – Period (Cs -T) curve that is used in the ELF procedure. As stated herein, the subject site is considered to be within a Site Class D-Default. A site-specific ground motion hazard analysis is not required for structures on Site Class D-Default with S1 > 0.2 provided that MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 16 the Seismic Response Coefficient, Cs, is determined in accordance with ASCE 7-16, Article 12.8 and structural design is performed in accordance with Equivalent Lateral Force (ELF) procedure. Allowable Bearing Capacity, Estimated Settlement and Lateral Resistance Existing Footings Existing footings that are at least 12 inches deep may be used to support the new additions provided that total loads from the existing and new construction do not exceed 1,500 pounds per square foot. If this load limit is exceeded, or if the existing footings do not meet the recommended embedment of at least 12 inches below adjacent finish grade, the existing footings will need to be underpinned or the new loads will need to be transferred to new footings. After the foundation plans have been prepared, the existing footings in all areas to receive additional loads should be randomly exposed and observed by the project structural engineer to verify that they will adequately support any new loads. Allowable Soil Bearing Capacities Pad Footings An allowable soil bearing capacity of 1,500 pounds per square foot may be utilized for design of isolated 24-inch-square footings founded at a minimum depth of 12 inches below the lowest adjacent final grade for pad footings that are not a part of the slab system and are used for support of such features as roof overhang, second-story decks, patio covers, etc. This value may be increased by 20 percent for each additional foot of depth and by 10 percent for each additional foot of width, to a maximum value of 2,500 pounds per square foot. The recommended allowable bearing value includes both dead and live loads, and may be increased by one-third for short duration wind and seismic forces. Continuous Footings An allowable soil bearing capacity of 1,500 pounds per square foot may be utilized for design of continuous footings founded at a minimum depth of 12 inches below the lowest adjacent final grade. This value may be increased by 20 percent for each additional foot of depth and by 10 percent for each additional foot of width, to a maximum value of 2,500 pounds per square foot. The recommended allowable bearing value includes both dead and live loads, and may be increased by one-third for short duration wind and seismic forces. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 17 Estimated Footing Settlement Based on the allowable bearing values provided above, total static settlement of the footings under the anticipated loads is expected to be on the order of ½ inch. Differential settlement is estimated to be on the order of 1/4 inch over a horizontal span of 40 feet. The majority of settlement is likely to take place as footing loads are applied or shortly thereafter. Lateral Resistance A passive earth pressure of 230 pounds per square foot per foot of depth, to a maximum value of 2,300 pounds per square foot, may be used to determine lateral bearing resistance for footings. In addition, a coefficient of friction of 0.35 times the dead load forces may be used between concrete and the supporting soils to determine lateral sliding resistance. The above values may be increased by one-third when designing for transient wind or seismic forces. It should be noted that the above values are based on the condition where footings are cast in direct contact with compacted fill or competent native soils. In cases where the footing sides are formed, all backfill placed against the footings upon removal of forms should be compacted to at least 90 percent of the applicable maximum dry density. Guidelines for Footings and Slabs on-Grade Design and Construction The results of our laboratory tests performed on representative samples of near-surface existing fill soils within the site during our investigation indicate that these materials predominantly exhibit expansion indices that are less than 20. As indicated in Section 1803.5.3 of 2022 California Building Code (2022 CBC), these soils are considered non-expansive. As such, the design of slabs on-grade is considered to be exempt from the procedures outlined in Sections 1808.6.2 of the 2022 CBC and may be performed using any method deemed rational and appropriate by the project structural engineer. However, the following minimum recommendations are presented herein for conditions where the project design team may require geotechnical engineering guidelines for design and construction of footings and slabs on-grade at the project site. The design and construction guidelines that follow are based on the above soil conditions and may be considered for reducing the effects of variability in fabric, composition and, therefore, the detrimental behavior of the site soils such as excessive short- and long-term total and differential heave or settlement. These guidelines have been developed on the basis of the previous experience of this firm on projects with similar soil conditions. Although construction performed in accordance with these guidelines has been found to reduce post-construction movement and/or distress, they generally do not positively eliminate all potential effects of variability in soils characteristics and future heave or settlement. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 18 It should also be noted that the suggestions for dimension and reinforcement provided herein are performance-based and intended only as preliminary guidelines to achieve adequate performance under the anticipated soil conditions. However, they should not be construed as replacement for structural engineering analyses, experience and judgment. The project structural engineer, architect and/or civil engineer should make appropriate adjustments to slab and footing dimensions, and reinforcement type, size and spacing to account for internal concrete forces (e.g., thermal, shrinkage and expansion) as well as external forces (e.g., applied loads) as deemed necessary. Consideration should also be given to minimum design criteria as dictated by local building code requirements. Conventional Slabs on-Grade System Given the expansion index of less than 20, and the characteristics as generally exhibited by onsite soils, we recommend that footings and floor slabs be designed and constructed in accordance with the following minimum criteria. Footings 1. Exterior continuous footings supporting one- and two-story structures should be founded at a minimum depth of 15 inches below the lowest adjacent final grade. Interior continuous footings may be founded at a minimum depth of 12 inches below the top of the adjacent finish floor slabs. Interior continuous footings width and spacing should be designed by the project structural engineer. 2. In accordance with Table 1809.7 of 2022 CBC for light-frame construction, all continuous footings should have minimum widths of 12 inches for one- and two-story construction. We recommend all continuous footings should be reinforced with a minimum of two No. 4 bars, one top and one bottom. 3. A minimum 12-inch-wide grade beam founded at the same depth as adjacent footings should be provided across the garage entrances or similar openings (such as large doors or bay windows). The grade beam should be reinforced in a similar manner as provided above. 4. Interior isolated pad footings, if required, should be a minimum of 24 inches square and founded at a minimum depth of 12 inches below the bottoms of the adjacent floor slabs. Pad footings should be reinforced with No. 4 bars spaced a maximum of 18 inches on centers, both ways, placed near the bottoms of the footings. 5. Exterior isolated pad footings intended for support of colonnades, roof overhangs, upper-story decks, patio covers, and similar construction should be a minimum of 24 inches square and founded at a minimum depth of 18 inches below the lowest adjacent final grade. The pad footings should be reinforced with No. 4 bars spaced a maximum of 18 inches on centers, both ways, placed near the bottoms of the footings. 6. Exterior isolated pad footings may need to be connected to adjacent pad and/or continuous footings via tie beams at the discretion of the project structural engineer. Further, where excessive soils settlement issues have been identified for this site elsewhere in the report, it is strongly recommended to tie all MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 19 footings both interior and exterior with a network of grade beams to reduce the potential differential settlement or isolated bearing distress issues below any independent footings. 7. The spacing and layout of the interior concrete grade beam system required below floor slabs should be determined by the project architect or structural engineer in accordance with the WRI publication using the effective plasticity index value provided previously. 8. To reduce the potential for distress due to differential settlement between the existing building footings and the new dwelling addition footings, the new footings should be doweled into the existing footings. This connection between the new and existing footings should be designed by the project structural engineer. 9. The minimum footing dimensions and reinforcement recommended herein may be modified (increased or decreased subject to the constraints of Chapter 18 of the 2022 CBC) by the structural engineer responsible for foundation design based on his/her calculations, engineering experience, and judgment. Building Floor Slabs 1. Concrete floor slabs should be a minimum 4 inches thick and reinforced with a minimum No. 3 bars spaced a maximum of 18 inches on centers, both ways. All slab reinforcement should be supported on concrete chairs or brick to ensure the desired placement near mid-depth. Slab dimension, reinforcement type, size and spacing need to account for internal concrete forces (e.g., thermal, shrinkage and expansion) as well as external forces (e.g., applied loads), as deemed necessary. It should be noted that some of the non-climatic site parameters, which may impact slabs on- grade performance, are not known at this time, as it is the case for many projects at the design stage. Some of these site parameters include unsaturated soils diffusion conditions pre- and post-construction (e.g., casting the slabs at the end of long, dry or wet periods, maintenance during long, dry and wet periods, etc.), landscaping, alterations in site surface gradient, irrigation, trees, etc. While the effects of any or a combination of these parameters on slab performance cannot be accurately predicted, maintaining moisture content equilibrium within the soils mass and planting trees at a distance greater than half of their mature height away from the edge of foundation may reduce the potential for the adverse impact of these site parameters on slabs on-grade performance. 2. To reduce the potential for distress due to differential settlement between the existing building slab and the new slabs of the dwelling additions, the new slabs should be doweled into the existing slab. This connection between the new and existing slabs should be designed by the project structural engineer. 3. Living area concrete floor slabs and areas to receive moisture sensitive floor covering should be underlain with a moisture vapor retarder consisting of a minimum 10-mil-thick polyethylene or polyolefin membrane that meets the minimum requirements of ASTM E96 and ASTM E1745 for vapor retarders (such as Husky Yellow Guard®, Stego® Wrap, or equivalent). All laps within the membrane should be sealed, and at least 2 inches of clean sand should be placed over the membrane to promote uniform curing of the concrete. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 20 In general, to reduce the potential for punctures, the membrane should be placed on a pad surface that has been graded smooth without any sharp protrusions. If a smooth surface cannot be achieved by grading, consideration should be given to lowering the pad finished grade an additional inch and then placing a 1-inch-thick leveling course of sand across the pad surface prior to the placement of the membrane. Foot traffic on the membrane should be reduced to a minimum. Additional steps would also need to be taken to prevent puncturing of the vapor retarder during concrete placement. To comply with Section 1907.1.1 of the 2022 CBC, the living area concrete floor slab should also be underlain with capillary break consisting of a minimum of 4 inches of gravel or crushed stone containing not more than 10 percent of material that passes through a No. 4 sieve. The capillary break should be placed below the 10-mil moisture vapor retarder. At the present time, some slab designers, geotechnical professionals and concrete experts view the sand layer below the slab (blotting sand) as a place for entrapment of excess moisture that could adversely impact moisture-sensitive floor coverings. As a preventive measure, the potential for moisture intrusion into the concrete slab could be reduced if the concrete is placed directly on the vapor retarder. However, if this sand layer is omitted, appropriate curing methods must be implemented to ensure that the concrete slab cures uniformly. A qualified contractor with experience in slab construction and curing should provide recommendations for alternative methods of curing and supervise the construction process to ensure uniform slab curing. 4. Garage floor slabs should be a minimum 4 inches thick and reinforced in a similar manner as living area floor slabs. Garage slabs should also be poured separately from adjacent wall footings with a positive separation maintained using ¾-inch-minimum felt expansion joint material. To control the propagation of shrinkage cracks, garage floor slabs should be quartered with weakened plane joints. Consideration should be given to placement of a moisture vapor retarder below the garage slab, similar to that provided in Item 2 above, should the garage slab be overlain with moisture sensitive floor covering. 5. To reduce the potential for excessive settlement and/or heave, slabs on-grade should be structurally connected to interior and exterior footings, and to grade beams if any, utilizing an appropriate reinforcement configuration at the discretion of the project structural engineer, for a monolithic performance. 6. Prior to placing concrete, the subgrade soils below living area floor slabs should be prewatered to achieve a moisture content that is at least 1.2 times the optimum moisture content. This moisture should penetrate to a depth of approximately 12 inches into the subgrade. 7. The minimum dimensions and reinforcement recommended herein for building floor slabs may be modified (increased or decreased subject to the constraints of Chapter 18 of the 2022 CBC) by the structural engineer responsible for foundation design based on his/her calculations and engineering experience and judgment. Foundation Observations All foundation excavations should be observed by a representative of the project geotechnical consultant to verify that they have been excavated into competent fill materials. These observations should be performed prior to the placement of forms or reinforcement. The excavations should be trimmed neat, level and square. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 21 All loose, sloughed or moisture-softened materials and/or any construction debris should be removed prior to the placement of concrete. Excavated soils derived from footing and utility trenches should not be placed in slab-on-grade areas unless they are compacted to at least 90 percent of maximum dry density. General Corrosivity Screening As a screening level study, limited chemical and electrical tests were performed on samples considered representative of the onsite soils to identify potential corrosive characteristics of these soils. The common indicators that are generally associated with soil corrosivity, among other indicators, include water-soluble sulfate (a measure of soil corrosivity on concrete), water-soluble chloride (a measure of soil corrosivity on metals embedded in concrete), pH (a measure of soil acidity), and minimum electrical resistivity (a measure of corrosivity on metals embedded in soils). Test methodology and results are presented in Appendix B. It should be noted that Petra does not practice corrosion engineering; therefore, the test results, opinion and engineering judgment provided herein should be considered as general guidelines only. Additional analyses, and/or determination of other indicators, would be warranted, especially, for cases where buried metallic building materials (such as copper and cast or ductile iron pipes) in contact with site soils are planned for the project. In many cases, the project geotechnical engineer may not be informed of these choices. Therefore, for conditions where such elements are considered, we recommend that other, relevant project design professionals (e.g., the architect, landscape architect, civil and/or structural engineer, etc.) to be involved. We also recommend considering a qualified corrosion engineer to conduct additional sampling and testing of near-surface soils during the final stages of site grading to provide a complete assessment of soil corrosivity. Recommendations to mitigate the detrimental effects of corrosive soils on buried metallic and other building materials that may be exposed to corrosive soils should be provided by the corrosion engineer as deemed appropriate. In general, a soil’s water-soluble sulfate levels and pH relate to the potential for concrete degradation; water-soluble chlorides in soils impact ferrous metals embedded or encased in concrete, e.g., reinforcing steel; and electrical resistivity is a measure of a soil’s corrosion potential to a variety of buried metals used in the building industry, such as copper tubing and cast or ductile iron pipes. Table 2, below, presents test results with an interpretation of current code approach and guidelines that are commonly used in building construction industry. The table includes the code-related classifications of the soils as they relate to the various tests, as well as a general recommendation for possible mitigation measures in view of the potential adverse impact of corrosive soils on various components of the proposed structures in direct contact with site soils. The guidelines provided herein should be evaluated and confirmed, or modified, in their entirety MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 22 by the project structural engineer, corrosion engineer and/or the contractor responsible for concrete placement for structural concrete used in exterior and interior footings, interior slabs on-ground, garage slabs, wall foundations and concrete exposed to weather such as driveways, patios, porches, walkways, ramps, steps, curbs, etc. TABLE 2 Soil Corrosivity Screening Results Test Test Results Classification General Recommendations Soluble Sulfates (Cal 417) 0.0015% S01 - Not Applicable Type II cement; minimum fc’ = 2,500 psi; no water/cement ratio restrictions. pH (Cal 643) 7.9 Moderately Alkaline2 Type I-P (MS) Modified or Type II Modified cement Soluble Chloride (Cal 422) 240 ppm C13 C24 Residence: No max water/cement ratio, f’c = 2,500 psi Spas/Decking: water/cement ratio 0.40, f’c = 5,000 psi Resistivity (Cal 643) 1,500 ohm-cm Highly Corrosive(5) Consult a corrosion engineer Notes: 1. ACI 318-14, Section 19.3 2. The United States Department of Agriculture Natural Resources Conservation Service, formerly Soil Conservation Service 3. ACI 318-14, Section 19.3 4. Exposure classification C2 applies specifically to swimming pools and appurtenant concrete elements 5. Pierre R. Roberge, “Handbook of Corrosion Engineering”” Masonry Block Walls Construction on Level Ground (Front Yard) Footings for free-standing (non-retaining) masonry block walls may be designed in accordance with the bearing and lateral resistance values provided previously for building footings. However, as a minimum, the wall footings should be embedded at a minimum depth of 12 inches below the lowest adjacent final grade. The footings should also be reinforced with a minimum of two No. 4 bars, one top and one bottom. In order to reduce the potential for unsightly cracking related to the possible effects of differential settlement and/or expansion, positive separations (construction joints) should also be provided in the block walls at each corner and at horizontal intervals of approximately 20 to 25 feet. The separations should be provided in the blocks and not extend through the footings. The footings should be poured monolithically with continuous rebars to serve as effective “grade beams” below the walls. Planter Walls Low-height planter walls should be supported by continuous concrete footings constructed in accordance with the recommendations presented previously for masonry block wall footings. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 23 Exterior Concrete Flatwork General Near-surface compacted fill soils within the site are variable in expansion behavior and are expected to exhibit very low to low expansion potential. For this reason, we recommend that all exterior concrete flatwork such as sidewalks, patio slabs, large decorative slabs, concrete subslabs that will be covered with decorative pavers, and private vehicular driveways within the site be designed by the project architect and/or structural engineer with consideration given to reducing the potential cracking and uplift that can develop in soils exhibiting expansion index values that fall in the low category. The guidelines that follow should be considered as minimums and are subject to review and revision by the project architect, structural engineer and/or landscape consultant as deemed appropriate. Thickness and Joint Spacing To reduce the potential of unsightly cracking, concrete walkways, patio-type slabs, large decorative slabs and concrete subslabs to be covered with decorative pavers should be at least 4 inches thick and provided with construction joints or expansion joints every 6 feet or less. Private driveways that will be designed for the use of passenger cars for access to private garages should also be at least 5 inches thick and provided with construction joints or expansion joints every 10 feet or less. Reinforcement All concrete flatwork having their largest plan-view panel dimension exceeding 5 feet should be reinforced with a minimum of No. 3 bars spaced 24 inches on centers, both ways. The reinforcement should be properly positioned near the middle of the slabs. The reinforcement recommendations provided herein are intended as guidelines to achieve adequate performance for anticipated soil conditions. The project architect, civil and/or structural engineer should make appropriate adjustments in reinforcement type, size and spacing to account for concrete internal (e.g., shrinkage and thermal) and external (e.g., applied loads) forces as deemed necessary. Edge Beams (Optional) Where the outer edges of concrete flatwork are to be bordered by landscaping, it is recommended that consideration be given to the use of edge beams (thickened edges) to prevent excessive infiltration and accumulation of water under the slabs. Edge beams, if used, should be 6 to 8 inches wide, extend 8 inches MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 24 below the tops of the finish slab surfaces. Edge beams are not mandatory; however, their inclusion in flatwork construction adjacent to landscaped areas is intended to reduce the potential for vertical and horizontal movement and subsequent cracking of the flatwork related to uplift forces that can develop in expansive soils. Subgrade Preparation Compaction To reduce the potential for distress to concrete flatwork, the subgrade soils below concrete flatwork areas to a minimum depth of 12 inches (or deeper, as either prescribed elsewhere in this report or determined in the field) should be moisture conditioned to at least equal to, or slightly greater than, the optimum moisture content and then compacted to a minimum relative compaction of 90 percent. Pre-Moistening As a further measure to reduce the potential for concrete flatwork cracking, subgrade soils should be thoroughly moistened prior to placing concrete. The moisture content of the soils should be at least 1.2 times the optimum moisture content and penetrate to a minimum depth of 12 inches into the subgrade. Pre- watering of the soils is intended to promote uniform curing of the concrete, reduce the development of shrinkage cracks and reduce the potential for differential expansion pressure on freshly poured flatwork. A representative of the project geotechnical consultant should observe and verify the density and moisture content of the soils, and the depth of moisture penetration prior to pouring concrete. Drainage Drainage from patios and other flatwork areas should be directed to local area drains and/or graded earth swales designed to carry runoff water to the adjacent streets or other approved drainage structures. The concrete flatwork should be sloped at a minimum gradient as discussed earlier in the Site Drainage section of this report, or as prescribed by project civil engineer or local codes, away from building foundations, retaining walls, masonry garden walls and slope areas. Tree Wells Tree wells are not recommended in concrete flatwork areas since they introduce excessive water into the subgrade soils and allow root invasion, both of which can cause heaving and cracking of the flatwork. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 25 Construction Along Top of Adjacent Descending Slope Improvements are not proposed within the rear yard area along the top of slope. Recommendations presented in this report are not applicable for other site locations other than those described in the “Proposed Construction” section of this report. An extensive supplemental field investigation would be required to prepare recommendations for any top of slope structures, should these improvements be proposed in the future. FUTURE IMPROVEMENTS Should any new structures or improvements be proposed at any time in the future other than those shown on the enclosed site plan and discussed herein, our firm should be notified so that we may provide design recommendations. Design recommendations are particularly critical for any new improvements that may be proposed on or near descending slopes, and in areas where they may interfere with the proposed permanent drainage facilities. As discussed above, an extensive supplemental field investigation would be required to prepare recommendations for any top of slope structures, should these improvements be proposed in the future. Potential problems can develop when drainage on the pad is altered in any way (i.e., excavations or placement of fills associated with construction of new walkways, patios, block walls and planters). Therefore, it is recommended that we be engaged to review the final design drawings, specifications and grading plan prior to any new construction. If we are not given the opportunity to review these documents with respect to the geotechnical aspects of new construction and grading, we can take no responsibility for misinterpretation of our recommendations presented herein. REPORT LIMITATIONS This report is based on the proposed project and geotechnical data as described herein. The materials encountered on the project site, described in other literature, and utilized in our laboratory investigation are believed representative of the project area, and the conclusions and recommendations contained in this report are presented on that basis. However, soil and bedrock materials can vary in characteristics between points of exploration, both laterally and vertically, and those variations could affect the conclusions and recommendations contained herein. As such, observation and testing by a geotechnical consultant during the grading and construction phases of the project are essential to confirming the basis of this report. To provide the greatest degree of continuity between the design and construction phases, consideration should be given to retaining Petra for construction services. MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 26 Our scope of services did not include geotechnical investigation within the rear yard of the property and did not include evaluation or stability analysis of the bluff slope descending from the rear yard of the property. Therefore, this report does not contain adequate information for use in the design and construction of any improvements in the back yard of the site and provides no opinions, recommendations, or conclusions regarding the stability of the back yard descending slope. Future development within the rear yard of the site should be based on additional testing and evaluation of site conditions in consideration of proposed development. A geotechnical consultant should be retained to provide additional investigation as deemed necessary to develop design and construction recommendations and to provide a bluff slope stability analysis. This report has been prepared consistent with the level of care being provided by other professionals providing similar services at the same locale and time period. The contents of this report are professional opinions and as such, are not to be considered a guarantee or warranty. This report should be reviewed and updated after a period of one year or if the project concept changes from that described herein. This report has not been prepared for use by parties or projects other than those named or described herein as it may not contain sufficient information for other parties or other purposes. This opportunity to be of service is sincerely appreciated. Please call if you have any questions pertaining to this report. Respectfully submitted, PETRA GEOSCIENCES, INC. ______________________________ Don Obert Associate Engineer RGE 2872 ______________________________ ______________________________ Evan Price Kurtis Morenz Associate Geologist Senior Staff Geologist CEG 2589 DO/EP/KM/lv W:\2020-2025\2023\200\23-234\Reports\23-234 110 Geotechnical Investigation.docx MR. CRAIG MACOMBER July 24, 2023 1812 Galaxy Drive / Newport Beach J.N. 23-234 Page 27 REFERENCES American Concrete Institute, 2014, Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary, Committee 318. American Society of Civil Engineers (ASCE), 2016, Minimum Design Loads for Buildings and Other Structures (Standard 7-16). California Building Standards Commission, 2022, California Building Code, California Code of Regulations, Title 24, Part 2, Volume 1 of 2, dated July. California Division of Mines and Geology, 1997, Seismic Hazard Zone Report for the Newport Beach 7.5-Minute Quadrangle, Orange County, California: California Department of Conservation Division of Mines and Geology, Seismic Hazard Zone Report 012. California Emergency Management Agency, 2019, Tsunami Inundation Map for Emergency Planning, State of California, County of Orange, Newport Beach Quadrangle: map prepared in cooperation with the California Geologic Survey and the University of Southern California, dated March 21. California Geological Survey, 2010, ‘Fault Activity Map of California, Geologic Data Map No. 6, http://maps.conservation.ca.gov/cgs/fam/. California Geological Survey, 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. Cao, T., Bryant, W.A., Rowshandel, B., Branum, D., and Willis, C.J., 2003, “The Revised 2002 California Probabilistic Seismic Hazard Maps”: California Division of Mines and Geology, Open-File Report 96-08. Federal Emergency Management Agency (FEMA), 2015, NEHERP (National Earthquake Hazards Reduction Program) Recommended Seismic Provision for New Building and Other Structures (FEMA P-1050). Grant, L. B. et al., 1999, Late Quaternary Uplift and Earthquake Potential of the San Joaquin Hills, Southern Los Angeles Basin, California. Geology, Vol. 27 No. 11, p. 1031-1034. Miller, R.V., and Tan, S.S., 1976, Geology and Engineering Geologic Aspects of the South Half Tustin Quadrangle, Orange County, California: California Division of Mines and Geology, Special Report 126 Morton, D.M., 2004, Preliminary Digital Geologic Map of the Santa Ana 30’ x 60’ Quadrangle, Southern California, United States Geological Survey, Open File Report 99-172, 2 Sheets, Scale 1:100,000. Morton, P.K., and Miller, R.V., 1981, Geologic Map of Orange County, California Showing Mines and Mineral Deposits: California Division of Mines and Geology, Scale 1" = 4000'. Morton, P.K., Miller, R.V., and Evans, J.R., 1976, Environmental Geology of Orange County, California: California Division of Mines and Geology, Open File Report 79-8 LA. SEAOC & OSHPD Seismic Design Maps Web Application – https://seismicmaps.org/ United States Geological Survey (USGS), 2014, Unified Hazard Tool, https://earthquake.usgs.gov/hazards/interactive/ FIGURES Scale: 1” = 2,000’ Base Map: Portions of USGS Newport Beach, Newport Beach South, Tustin, and Laguna Beach Quadrangles 7.5-Minute Topographic Series, 2015 N 3186 Airway Avenue, Suite K Costa Mesa, California 92626 PHONE: (714) 549-8921 SITE LOCATION MAP 1812 Galaxy Drive Newport Beach, California DATE: July 2023 J.N.: 23-234 Figure 1 COSTA MESA TEMECULA LOS ANGELES PALM DESERT CORONA ESCONDIDO PETRA GEOSCIENCES, INC. SITE N COSTA MESA TEMECULA LOS ANGELES PALM DESERT CORONA ESCONDIDO 3186 Airway Avenue, Suite K Costa Mesa, California 92626 PHONE: (714) 549-8921 BORING LOCATION MAP 1812 Galaxy Drive Newport Beach, California DATE: July, 2023 J.N.: 23-234 Figure 2 PETRA GEOSCIENCES, INC. HA-2 TD=5.5’ HA-2 TD=8’ af Qes B-1 TD=51.5’ B-2 TD=26.5’ B-3 TD=26.5’ B-4 TD=26.5’ 365365TP-1 TD=5’ TP-2 TD=5’ Qyf af B-1 TD=5’ B-2 TD=21.5’ B-3 TD=61.5’ EXPLANATION Artificial Fill, undocumented Very Old Paralic Deposits; circled where buried Approximate Location of Exploratory Boring TD= Total Depth afu HA-2 TD=5.5’ Proposed Remodel HA-1 TD=12’ PR Limits of Report Base Map: Graphic Impact “Site Plan & Details for 1812 Galaxy Dr., NB” Sheet A1, dated 1/26/23. Qvop afu Qvop afu Qvop Scale: 1” = 20’ 0 10 20 GEOTECHNICAL MAP APPENDIX A EXPLORATION LOGS Key to Soil and Bedrock Symbols and Terms Co a r s e - g r a i n e d So i l s >1 / 2 o f m a t e r i a l s i s la r g e r t h a n # 2 0 0 si e v e Fi n e - g r a i n e d S o i l s > 1 / 2 o f m a t e r i a l s i s sm a l l e r t h a n # 2 0 0 si e v e Th e N o . 2 0 0 U . S . S t a n d a r d S i e v e i s a b o u t t h e sm a l l e s t p a r t i c l e v i s i b l e t o t h e n a k e d e y e GRAVELS more than half of coarse fraction is larger than #4 sieve SANDS more than half of coarse fraction is larger than #4 sieve SILTS & CLAYS Liquid Limit Less Than 50 SILTS & CLAYS Liquid Limit Greater Than 50 Clean Gravels (less than 5% fines) Gravels with fines Clean Sands (less than 5% fines) Sands with fines Highly Organic Soils Well-graded gravels, gravel-sand mixtures, little or no finesGW GP GM GC SW SP SM SC ML CL OL MH CH OH PT Poorly-graded gravels, gravel-sand mixtures, little or no fines Silty Gravels, poorly-graded gravel-sand-silt mixtures Clayey Gravels, poorly-graded gravel-sand-clay mixtures Well-graded sands, gravelly sands, little or no fines Poorly-graded sands, gravelly sands, little or no fines Silty Sands, poorly-graded sand-gravel-silt mixtures Clayey Sands, poorly-graded sand-gravel-clay mixtures Inorganic silts & very fine sands, silty or clayey fine sands, clayey silts with slight plasticity Organic silts & clays of low plasticity Inorganic silts, micaceous or diatomaceous fine sand or silt Inorganic clays of high plasticity, fat clays Organic silts and clays of medium-to-high plasticity Peat, humus swamp soils with high organic content Description Sieve Size Grain Size Approximate Size Boulders >12">12"Larger than basketball-sized Cobbles 3 - 12"3 - 12"Fist-sized to basketball-sized Gravel Sand Fines Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays coarse fine coarse medium fine 3/4 - 3"3/4 - 3" #4 - 3/4 0.19 - 0.75" Thumb-sized to fist-sized #10 - #4 0.079 - 0.19" Pea-sized to thumb-sized #40 - #10 0.017 - 0.079" #200 - #40 0.0029 - 0.017" Passing #200 <0.0029" Rock salt-sized to pea-sized Sugar-sized to rock salt-sized Flour-sized to sugar-sized to Flour-sized and smaller Trace Few Some Numerous < 1% 1 - 5% 5 - 12% 12 - 20% Laboratory Test Abbreviations MAX Maximum Dry Density EXP Expansion Potential SO4 Soluble Sulfate Content RES Resistivity pH Acidity CON Consolidation SW Swell CL Chloride Content RV R-Value MA Mechanical (Particle Size) Analysis AT Atterberg Limits #200 #200 Screen Wash DSU Direct Shear (Undisturbed Sample) DSR Direct Shear (Remolded Sample) HYD Hydrometer Analysis SE Hydrometer Analysis OC Organic Content COMP Mortar Cylinder Compression Approximate Depth of Seepage Approximate Depth of Standing Groundwater Modified California Split Spoon Sample Standard Penetration Test Bulk Sample No Recovery in Sampler Shelby Tube Soft Moderately Hard Hard Very Hard Can be crushed and granulated by hand; "soil like" and structureless Can be grooved with fingernails; gouged easily with butter knife; crumbles under light hammer blow Cannot break by hand; can be grooved with a sharp knife; breaks with a moderate hammer blow Sharp knife leaves scratch; chips with repeated hammer blows Notes: Blows Per Foot: Number of blows required to advance sampler 1 foot (unless a lesser distance is specified). Samplers in general were driven into the soil or bedrock at the bottom of the hole with a standard (140 lb.) hammer dropping a standard 30 inches unless noted otherwise in Log Notes. Drive samples collected in bucket auger borings may be obtained by dropping non-standard weight from variable heights. When a SPT sampler is used the blow count conforms to ASTM D-1586. Unified Soil Classification System Grain Size Modifiers Sampler and Symbol Descriptions Bedrock Hardness Dry Slightly Moist Moist VeryMoist Wet (Saturated) Moisture Content 0 5 10 15 20 25 30 ARTIFICIAL FILL, undocumented (afu) Sandy Clay (CL): Brown, moist, soft to firm, fine-grained sand. Sand (SP): Off-white to yellow, moist, medium-dense, medium- to coarse-grained sand, poorly sorted, abundant shells (Bay dredge fill). VERY OLD PARALIC DEPOSITS (Qvop) Sandy Clay (CL): Gray with trace orange staining, moist, stiff, trace roots, moderately plastic. Total Depth= 12' No groundwater encountered Boring backfilled with cuttings. 84.6 32.5 Project:New Addition Boring No.:HA-1 Location:1812 Galaxy Drive, Newport Beach Elevation:±88' Job No.:23-234 Client:Craig Macomber Date:6/13/2023 Drill Method:Hand Auger Driving Weight:Hand Driven Logged By:KTM Depth (Feet) Lith- ology Material Description W A T E R Blows per 6 in. Samples C o r e B u l k Moisture Content (%) Laboratory Tests Dry Density (pcf) Other Lab Tests E X P L O R A T I O N L O G Petra Geosciences, Inc. PLATE A-1 Sample disturbed. 0 5 10 15 20 25 30 ARTIFICIAL FILL, undocumented (afu) Sandy Clay (CL): Dark brown, moist, soft, fine-grained sand. Sand (SP): Brown to gray, moist, medium-dense, medium- to coarse-grained sand, poorly sorted, abundant shells (Bay dredge fill). VERY OLD PARALIC DEPOSITS (Qvop) Sandy Clay (CL): Olive gray, moist, stiff, medium-grained sand, moderately plastic. Total Depth= 5.5' No groundwater encountered Boring backfilled with cuttings. MAX, EI, SO4, AT, RES, CL, pH, DSR Project:New Addition Boring No.:HA-2 Location:1812 Galaxy Drive, Newport Beach Elevation:±88' Job No.:23-234 Client:Craig Macomber Date:6/13/2023 Drill Method:Hand Auger Driving Weight:Hand Driven Logged By:KTM Depth (Feet) Lith- ology Material Description W A T E R Blows per 6 in. Samples C o r e B u l k Moisture Content (%) Laboratory Tests Dry Density (pcf) Other Lab Tests E X P L O R A T I O N L O G Petra Geosciences, Inc. PLATE A-2 Sample disturbed. APPENDIX B LABORATORY TEST PROCEDURES LABORATORY DATA SUMMARY _____________________________________________________ ______________________________________ PETRA GEOSCIENCES, INC. Laboratory Address: 1251 W. Pomona Road, Unit 103, Corona, CA, 92882 J.N. 23-234 LABORATORY TEST PROCEDURES Soil Classification Soil materials encountered within the property were classified and described in accordance with the Unified Soil Classification System and in general accordance with the current version of Test Method ASTM D 2488. The assigned group symbols are presented in the exploration logs, Appendix A. In Situ Moisture Content and Dry Unit Weight In-place moisture content and dry unit weight of selected, relatively undisturbed soil samples were determined in accordance with the current version of the Test Method ASTM D 2435 and Test Method ASTM D 2216, respectively. Test data are presented on the exploration logs, Appendix A. Laboratory Maximum Dry Unit Weight and Optimum Moisture Content The maximum dry unit weight and optimum moisture content of the on-site soils were determined for a selected bulk sample in accordance with current version of ASTM D 1557. The results of this test are presented on Plate B-1. Expansion Index An expansion index test was performed on a selected bulk sample of the on-site soils in accordance with the current version of Test Method ASTM D 4829. The test results are presented on Plate B-1. Corrosivity Screening Chemical and electrical analyses were performed on a selected bulk sample of onsite soils to determine their soluble sulfate content, chloride content, pH (acidity), and minimum electrical resistivity. These tests were performed in accordance with the current versions of California Test Method Nos. CTM 417, CTM 422 and CTM 643, respectively. The results of these tests are included on Plate B-1. Atterberg Limits The Atterberg limits (liquid limit and plastic limit) were determined for a selected bulk sample of representative materials in accordance with the current version of Test Method ASTM D 4318. The soil was found to be non-plastic. Direct Shear The Coulomb shear strength parameters, i.e., angle of internal friction and cohesion, were determined for a selected, reconstituted-bulk sample of onsite soil. The test was performed in general accordance with the current version of Test Method ASTM D 3080. Three specimens were prepared for each test. The test specimens were inundated and then sheared under various normal loads at a constant strain rate of 0.005 inch per minute. The results of the direct shear test are graphically presented on Plate B-2. __________________________________________________________________________________________________________________________________________ PETRA GEOSCIENCES, INC. Laboratory Address: 1251 W. Pomona Road, Unit 103, Corona, CA, 92882 J.N. 23-234 PLATE B-1 LABORATORY DATA SUMMARY* Boring Number Sample Depth (ft) Soil Description Max. Dry Density 1 (pcf) Optimum Moisture1 (%) Expansion Index2 Expansion Potential Classification3 Atterberg Limits4 Sulfate Content5 (%) Chloride Content6 (ppm) pH7 Minimum Resistivity7 (Ohm-cm) LL PL PI HA-1 0-5 Clayey Sand (SC) 122.0 10.0 3 Very Low NP NP NP 0.0015 240 7.9 1,500 HA-1 & HA-2 Mix of 3 & 4 Sandy Clay (CL) - - 16 Very Low - - - - - - - *Note: Laboratory data pertaining to in-place soil moisture content and dry density are provided on the exploration logs included in Appendix A of this report. NP = Non Plastic Test Procedures: 1 Per ASTM Test Method D 1557 5 Per Caltrans Test Method 417 2 Per ASTM Test Method D 4829 6 Per Caltrans Test Method 422 3 Per ASTM Test Method D 4829 Table 1 7 Per Caltrans Test Method 643 4 Per ASTM Test Method D 4318 Tested By: DI Client: Galaxy Project: Addition Galaxy, Newport Beach Source of Sample: 23L158 Depth: 0-3 Sample Number: HA-2 Proj. No.: 23-234 Date Sampled: Sample Type: Remold Description: Brown, silty fine to coarse grained sand Specific Gravity= 2.65 Remarks: Figure Sample No. Water Content, % Dry Density, pcf Saturation, % Void Ratio Diameter, in. Height, in. Water Content, % Dry Density, pcf Saturation, % Void Ratio Diameter, in. Height, in. Normal Stress, ksf Fail. Stress, ksf Strain, % Ult. Stress, ksf Strain, % Strain rate, in./min. In i t i a l At T e s t Sh e a r S t r e s s , k s f 0 0.5 1 1.5 2 2.5 3 Strain, % 0 5 10 15 20 1 2 3 Ve r t i c a l D e f o r m a t i o n , i n . 0.03 0.02 0.01 0 -0.01 -0.02 -0.03 Strain, % 0 3 6 9 12 Dilation Consol. 1 2 3 Ul t . S t r e s s , k s f Fa i l . S t r e s s , k s f 0 2 4 6 Normal Stress, ksf 0 2 4 6 C, ksf f, deg Tan(f) Fail.Ult. 0.41 30.4 0.59 0.26 28.9 0.55 1 4.0 115.3 24.4 0.4350 2.42 1.01 15.5 116.3 97.3 0.4229 2.42 1.00 1.00 1.00 2.3 0.84 10.3 0.040 2 4.0 116.0 24.9 0.4259 2.42 1.00 14.6 117.4 94.5 0.4090 2.42 0.99 2.00 1.60 2.5 1.33 9.3 0.040 3 4.0 115.3 24.4 0.4345 2.42 1.01 14.7 118.7 98.6 0.3936 2.42 0.98 4.00 2.76 2.9 2.48 10.3 0.040 Plate B-2 APPENDIX C SEISMIC DESIGN ANALYSES 7/21/23, 5:49 PM U.S. Seismic Design Maps https://www.seismicmaps.org 1/2 Latitude, Longitude: 33.6367, -117.8918 Date 7/21/2023, 5:49:54 PM Design Code Reference Document ASCE7-16 Risk Category II Site Class D - Default (See Section 11.4.3) Type Value Description SS 1.342 MCER ground motion. (for 0.2 second period) S1 0.478 MCER ground motion. (for 1.0s period) SMS 1.611 Site-modified spectral acceleration value SM1 null -See Section 11.4.8 Site-modified spectral acceleration value SDS 1.074 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 0.582 MCEG peak ground acceleration FPGA 1.2 Site amplification factor at PGA PGAM 0.698 Site modified peak ground acceleration TL 8 Long-period transition period in seconds SsRT 1.342 Probabilistic risk-targeted ground motion. (0.2 second) SsUH 1.467 Factored uniform-hazard (2% probability of exceedance in 50 years) spectral acceleration SsD 2.566 Factored deterministic acceleration value. (0.2 second) S1RT 0.478 Probabilistic risk-targeted ground motion. (1.0 second) S1UH 0.518 Factored uniform-hazard (2% probability of exceedance in 50 years) spectral acceleration. S1D 0.827 Factored deterministic acceleration value. (1.0 second) PGAd 1.042 Factored deterministic acceleration value. (Peak Ground Acceleration) PGAUH 0.582 Uniform-hazard (2% probability of exceedance in 50 years) Peak Ground Acceleration CRS 0.915 Mapped value of the risk coefficient at short periods CR1 0.924 Mapped value of the risk coefficient at a period of 1 s CV 1.368 Vertical coefficient 7/21/23, 5:49 PM U.S. Seismic Design Maps https://www.seismicmaps.org 2/2 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. 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