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PC - Item 3B - Exhibit F - Appendix D Preliminary Geotechnical Investigation1011 N. Armando Street, Anaheim, CA 92806-2606 (714) 630-1626 October 27, 2021 J.N.: 3016.00 Mr. Erik Pfahler Borstein Enterprises 11766 Wilshire Boulevard, Suite 820 Los Angeles, CA 90025 Subject: Preliminary Geotechnical Investigation, Proposed Residential Development, 8601 Mission Drive, Rosemead, California Dear Mr. Pfahler, Pursuant to your request, Albus & Associates, Inc. is pleased to present to you our preliminary geotechnical investigation report, for the proposed development at the subject site. This report presents the results of our aerial photo and literature review, subsurface exploration, laboratory testing, and engineering analyses. Conclusions and recommendations pertaining to the proposed site development are also presented herein based on the findings of our work. We appreciate this opportunity to be of service to you. If you should have any questions regarding the contents of this report, please do not hesitate to call. Sincerely, ALBUS & ASSOCIATES, INC. David E. Albus Principal Engineer Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page i TABLE OF CONTENTS ALBUS & ASSOCIATES, INC. 1.0 INTRODUCTION..................................................................................................................... 1 1.0 PURPOSE AND SCOPE ........................................................................................................ 1 1.1 SITE LOCATION AND DESCRIPTION ............................................................................... 1 1.2 PROPOSED DEVELOPMENT .............................................................................................. 2 2.0 INVESTIGATION .................................................................................................................... 3 2.1 RESEARCH ............................................................................................................................ 3 2.2 SUBSURFACE EXPLORATION .......................................................................................... 3 2.3 LABORATORY TESTING .................................................................................................... 3 3.0 SUBSURFACE CONDITIONS ............................................................................................... 4 3.1 SOIL CONDITIONS ............................................................................................................... 4 3.2 GROUNDWATER .................................................................................................................. 4 3.3 FAULTING ............................................................................................................................. 4 4.0 ANALYSES ............................................................................................................................... 5 4.1 SEISMICITY ........................................................................................................................... 5 4.2 STATIC SETTLEMENT ........................................................................................................ 6 5.0 CONCLUSIONS ....................................................................................................................... 7 5.1 FEASIBILITY OF PROPOSED DEVELOPMENT ............................................................... 7 5.2 GEOLOGIC HAZARDS ......................................................................................................... 7 5.2.1 Ground Rupture ................................................................................................................ 7 5.2.2 Ground Shaking ................................................................................................................ 7 5.2.3 Landsliding ....................................................................................................................... 7 5.2.4 Liquefaction ...................................................................................................................... 7 5.3 STATIC SETTLEMENT ........................................................................................................ 8 5.4 EXCAVATION AND MATERIAL CHARACTERISTICS .................................................. 8 5.5 SHRINKAGE AND SUBSIDENCE ....................................................................................... 8 5.6 SOIL EXPANSION ................................................................................................................. 9 6.0 RECOMMENDATIONS .......................................................................................................... 9 6.1 EARTHWORK ........................................................................................................................ 9 6.1.1 General Earthwork and Grading Specifications ............................................................... 9 6.1.2 Pre-Grade Meeting and Geotechnical Observation .......................................................... 9 6.1.3 Site Clearing...................................................................................................................... 9 6.1.4 Ground Preparation ......................................................................................................... 10 6.1.5 Fill Placement ................................................................................................................. 10 6.1.6 Import Materials .............................................................................................................. 10 6.1.7 Temporary Excavations .................................................................................................. 11 6.2 SEISMIC DESIGN PARAMETERS .................................................................................... 11 6.2.1 Mapped Seismic Design Parameters ............................................................................... 11 6.2.2 Site-Specific Seismic Design Parameters ....................................................................... 12 6.3 CONVENTIONAL FOUNDATION DESIGN ..................................................................... 12 6.3.1 General ............................................................................................................................ 12 6.3.2 Soil Expansion ................................................................................................................ 12 6.3.3 Static and Seismic Settlement ......................................................................................... 13 6.3.4 Allowable Bearing Value ................................................................................................ 13 6.3.5 Lateral Resistance ........................................................................................................... 13 6.3.6 Footing and Slab on Grade ............................................................................................. 13 Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page ii ALBUS & ASSOCIATES, INC. 6.3.7 Foundation Observations ................................................................................................ 14 6.4 RETAINING AND SCREENING WALLS.......................................................................... 14 6.4.1 General ............................................................................................................................ 14 6.4.2 Allowable Bearing Value and Lateral Resistance .......................................................... 14 6.4.3 Active Earth Pressures .................................................................................................... 15 6.4.4 Drainage and Moisture-Proofing .................................................................................... 15 6.4.5 Foundation Observations ................................................................................................ 15 6.5 EXTERIOR FLATWORK .................................................................................................... 16 6.6 CONCRETE MIX DESIGN .................................................................................................. 17 6.7 CORROSION ........................................................................................................................ 17 6.8 PRELIMINARY PAVEMENT DESIGN ............................................................................. 17 6.8.1 Preliminary Pavement Structural Sections ...................................................................... 17 6.8.2 Subgrade Preparation ...................................................................................................... 18 6.8.3 Aggregate Base ............................................................................................................... 18 6.8.4 Asphaltic Concrete .......................................................................................................... 18 6.8.5 Concrete Paver ................................................................................................................ 18 6.8.6 Portland Cement Concrete .............................................................................................. 18 6.9 POST GRADING CONSIDERATIONS .............................................................................. 19 6.9.1 Site Drainage and Irrigation ............................................................................................ 19 6.9.2 Utility Trenches .............................................................................................................. 19 6.10 PLAN REVIEW AND CONSTRUCTION SERVICES ................................................... 20 7.0 LIMITATIONS ....................................................................................................................... 20 8.0 REFERENCES ........................................................................................................................ 22 FIGURES AND PLATES Figure 1 - Site Location Map Plate 1 - Geotechnical Map APPENDICES APPENDIX A - EXPLORATION LOGS Plates A-1 through A-8 APPENDIX B - LABORATORY TESTS RESULTS Table B – Summary of Laboratory Test Results Plate B-1 through B-2 – Grain Size Distribution Plot Plate B-3 – Direct Shear Plot Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 1 ALBUS & ASSOCIATES, INC. 1.0 INTRODUCTION 1.0 PURPOSE AND SCOPE The purposes of our preliminary geotechnical investigation were to evaluate geotechnical conditions within the project area and to provide conclusions and recommendations relevant to the design and construction of the proposed improvements at the subject site. The scope of this investigation included the following:  Review of the historical aerial photographs  Review of published geologic and seismic data for the site and surrounding area  Exploratory drilling and soil sampling  Laboratory testing of selected soil samples  Engineering analyses of data obtained from our review, exploration, and laboratory testing  Evaluation of site seismicity, liquefaction potential, and settlement potential  Preparation of this report 1.1 SITE LOCATION AND DESCRIPTION The site is located at 8601 Mission Drive within the city of Rosemead, California. The APN parcel numbers for the current development are 5389-009-029, -030, and -031. The property is bordered by Mission Drive to the south, Walnut Grove Avenue, an existing easement for power lines, and a nursery to the west, and single-family residences to the north and east. The location of the site and its relationship to the surrounding areas are shown in Figure 1, Site Location Map. The site consists of an irregularly shaped property containing approximately 3.35 acres of land. The site is relatively flat with elevations ranging from 357 to 363 feet above mean sea level (based on Google Earth). The site slopes gently down to the south. The site is currently vacant land with some improvements onsite. The perimeters of the site are bounded by chain-link fencing, masonry block walls, and plastic fencing. A short concrete driveway is located to the south and west. Along the southwest boundary of the property is existing overhead powerlines. Vegetation within the site consists of minor ground cover and some large palm trees within the southwest portion of the site. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 2 ALBUS & ASSOCIATES, INC. © 2021 Google N FIGURE 1-SITE LOCATION MAP Proposed Residential Development 8601 Mission Drive, Rosemead, California NOT TO SCALE 1.2 PROPOSED DEVELOPMENT Based on our understanding, site development is anticipated to consist of multi-story (2 to 3), wood- framed buildings at grade. Associated interior driveways, decorative hardscape, parking areas and underground utilities are also anticipated. No grading or structural plans were available in preparing this proposal. However, we anticipate some minor cut and filling of the site will be required to achieve future surface configuration and we expect future foundation loads will be moderate. SITE Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 3 ALBUS & ASSOCIATES, INC. 2.0 INVESTIGATION 2.1 RESEARCH We have reviewed the referenced geologic publications and maps (see references). Data from these sources were utilized to develop some of the findings and conclusions presented herein. We have also reviewed available historical aerial photographs. The aerial photos indicate that in 1953, the site appears to have been graded but no improvements were constructed. By 1965, a large building had been constructed with a driveway entering from Walnut Grove Avenue to the western side of the building. An additional entrance from Mission drive runs to the south of the building and joins what appears to be an asphaltic parking area occupying the areas east and north of the building. From 1965 to 1988, the site appears relatively unchanged. By 1990, the building and associated improvements were gone and the site appears to have remained relatively unchanged since. 2.2 SUBSURFACE EXPLORATION Subsurface exploration for this investigation was conducted on September 7, 2021, and consisted of drilling six (6) soil borings to depths ranging from approximately 11.5 to 51.5 feet below the existing ground surface (bgs). The borings were drilled using a truck-mounted, continuous flight, hollow- stem-auger drill rig. A representative of Albus & Associates, Inc. logged the exploratory borings. Visual and tactile identifications were made of the materials encountered, and their descriptions are presented in the Exploration Logs in Appendix A. The approximate locations of the exploratory excavations completed by this firm are shown on the enclosed Geotechnical Map, Plate 1. Bulk, relatively undisturbed and Standard Penetration Test (SPT) samples were obtained at selected depths within the exploratory borings for subsequent laboratory testing. Relatively undisturbed samples were obtained using a 3-inch O.D., 2.5-inch I.D., California split-spoon soil sampler lined with brass rings. SPT samples were obtained from the boring using a standard, unlined SPT soil sampler. During each sampling interval, the sampler was driven 18 inches with successive drops of a 140-pound automatic hammer falling 30 inches. The number of blows required to advance the sampler was recorded for each six inches of advancement. The total blow count for the lower 12 inches of advancement per soil sample is recorded on the exploration log. Samples were placed in sealed containers or plastic bags and transported to our laboratory for analyses. The borings were backfilled with auger cuttings upon completion of sampling. Two additional borings (P-1 and P-2) were drilled adjacent to boring B-1 for percolation testing. Details and results of percolation tests are reported under a separate cover. 2.3 LABORATORY TESTING Selected samples obtained from our subsurface exploration were tested in our soil laboratory. Tests consisted of in-situ moisture content and dry density, maximum dry density and optimum moisture content, expansion index, soluble sulfate content, direct shear, consolidation/collapse potential, grain- size distribution analysis, Atterberg limits, passing 200, and corrosivity testing (pH, chloride, and resistivity). A description of laboratory test criteria and test results are presented in Appendix B. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 4 ALBUS & ASSOCIATES, INC. 3.0 SUBSURFACE CONDITIONS 3.1 SOIL CONDITIONS Review of the Diblee Map for the El Monte and Baldwin Park Quadrangles shows the site is designated as Quaternary Alluvium and falls within a flood plain and would have been subjected to seasonally- deposited materials associated with heavy rains from nearby mountain ranges to the north. Our exploration encounted artificial fills overlaying alluvial soils. Descriptions of the earth materials encountered during our investigation are summarized below and are presented in detail on the Exploration Logs presented in Appendix A. Fills up to about 2 feet thick appear to be present on site due to previous site improvements and grading. Fill materials typically consisted of fine to medium-grained silty sands. Alluvium was encountered underlying the artificial fill and generally consisted of interlayered silty sands, sands with silt, gravelly sands, and clayey sands. These materials were typically medium dense to very dense and damp. Alluvial soils were encountered to the maximum depth explored (51.5 feet). Within borings B-2 and B-3, cobbles were encountered at depths of approximately 10 feet. Due to the size of the cobbles, the hollow stem could not extract all the cobbles. As such, the cobbles generally remained within the borings and floated within the cuttings and around the stem. Sizes were either measured or visually observed within the boring shaft and are estimated to be 4 to 6 inches in diameter. 3.2 GROUNDWATER Groundwater was not encountered during this firm’s subsurface exploration to a depth of 51.5 feet. The CDMG Special Report 024 suggests that historic high groundwater for the subject site is approximately 60 feet. However, review of the Los Angeles County groundwater level data for the nearby well 2920G indicates that groundwater for the area is 231 feet below ground surface as of 2018. Well readings have been recorded from 5/1/1949 to 4/26/2018, and during this period, groundwater has fluctuated, but has continued to increase in depth from 126 feet (bgs) to 231 feet (bgs) during this time period. The last recorded reading at the time of this report was April 26, 2018 and indicated a depth of 231 feet. 3.3 FAULTING Based on our review of the referenced publications and seismic data, no active faults are known to project through or immediately adjacent to the subject sites and the sites do not lie within an “Earthquake Fault Zone” as defined by the State of California in Earthquake Fault Zoning Act. Table 3.1 presents a summary of known seismically active faults within 10 miles of the sites based on the 2008 USGS National Seismic Hazard Maps. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 5 ALBUS & ASSOCIATES, INC. TABLE 3.1 Summary of Faults Name Dist. (miles) Slip Rate (mm/yr.) Preferred Dip (degrees) Slip Sense Rupture Top (km) Fault Length (km) Elysian Park (Upper) 1.74 1.3 50 reverse 3 20 Raymond 2.81 1.5 79 strike slip 0 22 Verdugo 5.15 0.5 55 reverse 0 29 Sierra Madre Connected 6.11 2 51 reverse 0 76 Sierra Madre 6.11 2 53 reverse 0 57 Elsinore;W+GI+T+J+CM 6.66 n/a 84 strike slip 0 241 Elsinore;W 6.66 2.5 75 strike slip 0 46 Elsinore;W+GI 6.66 n/a 81 strike slip 0 83 Elsinore;W+GI+T 6.66 n/a 84 strike slip 0 124 Elsinore;W+GI+T+J 6.66 n/a 84 strike slip 0 199 Clamshell-Sawpit 7.75 0.5 50 reverse 0 16 Puente Hills (LA) 8.61 0.7 27 thrust 2.1 22 4.0 ANALYSES 4.1 SEISMICITY 2019 CBC requires seismic parameters in accordance with ASCE 7-16. Unless noted otherwise, all section numbers cited in the following refer to the sections in ASCE 7-16. Per Section 20.3 the project site was designated as Site Class D. We used the OSHPD seismic hazard tool to obtain the basic mapped acceleration parameters, including short periods (SS) and 1-second period (S1) MCER Spectral Response Accelerations. Section 11.4.8 requires site-specific ground hazard analysis for structures on Site Class E with SS greater than or equal to 1.0 or Site Class D or E with S1 greater than or equal to 0.2. Based on the mapped values of SS and S1 the project site falls within this category, requiring site specific hazard analysis in accordance with Section 21.2. However, “A ground motion hazard analysis is not required for structures where: Structures on Site Class D sites with S1 greater than or equal to 0.2, provided the value of the seismic response coefficient Cs is determined by Eq. (12.8-2) for values of T ≤ 1.5Ts and taken as equal to 1.5 times the value computed in accordance with either Eq. (12.8-3) for TL ≥ T > 1.5Ts or Eq. (12.8-4) for T > TL.” Assuming this exception is met for this project, a ground motion hazard analysis is not required and mapped seismic values can be used. Should this exception not be met, a ground motion hazard analysis Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 6 ALBUS & ASSOCIATES, INC. is required to determine the Design response spectra for the proposed structures at this site. Both mapped and site-specific seismic design parameters are provided in this report as presented in Section 6.2. Details of a ground motion hazard analysis are explained below. According to Section 21.2.3 (Supplement 1), the site-specific Risk Targeted Maximum Considered Earthquake (MCER) spectral response acceleration at any period is the lesser of the probabilistic and the deterministic response accelerations, subject to the exception specified in the same section. The probabilistic response spectrum was developed using the computer program OpenSHA (Field et al., 2013), which implements Method 1 as described in Section 21.2.1.1. Fault Models 3.1 and 3.2 from the Third Uniform California Earthquake Rupture Forecast (UCERF3) were used as the earthquake rupture forecast models for the PSHA. In addition to known fault sources, background seismicity was also included in the PSHA. The ground motion Prediction Equations (GMPEs) selected for use in this analysis are those developed for the Pacific Earthquake Engineering Research Center (PEER) Next Generation Attenuation (NGA) West 2 project. Four GMPEs - Abrahamson et al. (2014), Boore et al. (2014), Campbell and Bozorgnia (2014), and Chiou and Youngs (2014) were used to perform the analysis. In accordance with Section 21.2.2 (Supplement 1), the deterministic spectral response acceleration at each period was calculated as the 84th percentile, 5% damped response acceleration, using NGA-West2 GMPE Worksheet. For this, the information from at least three causative faults with the greatest contribution per deaggregation analysis were used and the larger acceleration spectrum among these was selected as the deterministic response spectrum. The deterministic spectrum was adjusted per requirements in Section 21.2.2 (Supplement 1) where applicable. Both probabilistic and deterministic spectra were subjected to the maximum direction scale factors specified in Section 21.2 to produce the maximum acceleration spectra. Design response spectrum was developed by subjecting the site-specific MCER response spectrum to the provisions outlined in Section 21.3. This process included comparison with 80% code-based design spectrum determined in accordance with Section 11.4.6. The short period and long period site coefficient (Fa and Fv, respectively) were determined per Section 21.3 in conjunction with Table 11.4- 1. Site-specific design acceleration parameters (SMS, SM1, SDS, and SD1) were calculated according to Section 21.4. Per Section 11.2 (definitions on Page 79 of ASCE7-16) for evaluation of liquefaction, lateral spreading, seismic settlements, and other soil-related issues, Maximum Considered Earthquake Geometric Mean (MCEG) peak ground acceleration PGAM shall be used. The site-specific PGAM is calculated per Section 21.5.3, as the lesser of the probabilistic PGAM (Section 21.5.1) and deterministic PGAM (Section 21.5.2), but no less than 80% site modified peak ground acceleration, PGAM, obtained from OSHPD seismic hazard tool. From our analyses, we obtain a PGAM of 0.762g. 4.2 STATIC SETTLEMENT Analyses were performed for the potential settlement of the underlying soils encountered during our investigation. The site is predominately granular in nature. As such, analyses of settlement were based on the elastic method using estimated modulli correlated from N60 blow counts. Two analyses were performed to evaluate settlement of the structures. The first model was based on a conventional shallow strip footing 1.2 feet wide and a wall load of 3,000 psf. The second model was based on a Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 7 ALBUS & ASSOCIATES, INC. conventional square footing with 3 feet width and a column load of 3,000 psf. Both models yielded a total settlement of less than 0.5 inches. Both analyses assume the upper 2 feet of existing fill soils would be removed and replaced as compacted fill. 5.0 CONCLUSIONS 5.1 FEASIBILITY OF PROPOSED DEVELOPMENT From a geotechnical point of view, the proposed site development is considered feasible, provided the recommendations presented in this report are incorporated into the design and construction of the project. Furthermore, it is also our opinion that the proposed development will not adversely impact the stability of adjoining properties. Key issues that could have significant fiscal impacts on the geotechnical aspects of the proposed site development are discussed in the following sections of this report. 5.2 GEOLOGIC HAZARDS 5.2.1 Ground Rupture No known active faults are known to project through the subject sites nor do the sites lie within the boundaries of an “Earthquake Fault Zone” as defined by the State of California in the Alquist-Priolo Earthquake Fault Zoning Act. The closest known active fault is the Elysian Park (Upper) fault located approximately 1.74 miles away. Therefore, potential for ground rupture due to an earthquake beneath the sites is considered low. 5.2.2 Ground Shaking The site is situated in a seismically active area that has historically been affected by generally moderate to occasionally high levels of ground motion. The site lies in relatively close proximity to several seismically active faults; therefore, during the life of the proposed improvements, the property will probably experience similar moderate to occasionally high ground shaking from these fault zones, as well as some background shaking from other seismically active areas of the Southern California region. Design and construction in accordance with the current California Building Code (CBC) requirements is anticipated to address the issues related to potential ground shaking. 5.2.3 Landsliding Geologic hazards associated with landsliding are not anticipated at the site since the site is relatively level. 5.2.4 Liquefaction Engineering research of soil liquefaction potential (Youd, et al., 2001) indicates that generally three basic factors must exist concurrently in order for liquefaction to occur. These factors include:  A source of ground shaking, such as an earthquake, capable of generating soil mass distortions.  A relatively loose silty and/or sandy soil. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 8 ALBUS & ASSOCIATES, INC.  A relative shallow groundwater table (within approximately 50 feet below ground surface) or completely saturated soil conditions that will allow positive pore pressure generation. The site is not located within a State-designated zone of potentially liquefiable soils. Additionally, groundwater was not encountered to the maximum depth of 51.5 feet drilled during our site exploration. Furthermore, groundwater well measurements by the Los Angeles County in the vicinity of the project site since 1949 indicate that groundwater has been deeper than 50 feet for more than 70 years (well 1617N). Therefore, historical high groundwater is anticipated to be deeper than 50 feet below the ground surface. As a result, the potential for liquefaction to occur beneath the site is considered very low. 5.3 STATIC SETTLEMENT Analyses were performed to evaluate potential for static settlement of the underlying alluvium. Provided site grading is performed in accordance with the recommendations provided herein and based on the anticipated relatively light foundation loads, total and differential static settlement is not anticipated to exceed 1 inch and ½-inch over 30 feet, respectively, for the proposed residential structure. The estimated magnitudes of static settlements are considered within tolerable limits for the proposed structure. 5.4 EXCAVATION AND MATERIAL CHARACTERISTICS Onsite earth materials are anticipated to be relatively easy to excavate with conventional heavy earthmoving equipment. The site earth materials are generally considered suitable for reuse as fill provided they are cleared on deleterious debris and oversized rocks (greater than 6 inches in greatest dimension). If encountered, portions of concrete debris and asphalt can likely be reduced in size (4” minus) and incorporated within fill soils during earthwork operations. Temporary construction slopes will be required to complete removal of unsuitable soils and for construction of underground utilities. Such excavations will require laybacks where they are surcharged or where they exceed 4 feet in height. Most of the near-surface soils are below optimum moisture content. As such, the addition of water to these materials will be required during placement and compaction as engineered fills. 5.5 SHRINKAGE AND SUBSIDENCE Volumetric changes in earth quantities will occur when excavated onsite soil materials are replaced as properly compacted fill. We estimate that the existing upper 5 feet of soils will shrink approximately 8 to 14 percent when removed and replaced as compacted fill. Subsidence due to reprocessing of removal bottoms is anticipated to be on the order of 0.10 feet. The estimates of shrinkage and subsidence are intended as an aid for project engineers in determining earthwork quantities. However, these estimates should be used with some caution since they are not absolute values. Contingencies should be made for balancing earthwork quantities based on actual shrinkage and subsidence that occurs during the grading process. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 9 ALBUS & ASSOCIATES, INC. 5.6 SOIL EXPANSION Based on our laboratory test results and the USCS visual manual classification, the near-surface soils are generally anticipated to possess a Very Low expansion potential. As such, special requirements as set forth in CBC Chapter 18 regarding expansive soils are not required. Additional testing for soil expansion will be required prior to construction of foundations and other concrete work to confirm these conditions. 6.0 RECOMMENDATIONS 6.1 EARTHWORK 6.1.1 General Earthwork and Grading Specifications All earthwork and grading should be performed in accordance with applicable requirements of Cal/OSHA, applicable specifications of the Grading Codes of the City of Rosemead, California in addition to the recommendations presented herein. 6.1.2 Pre-Grade Meeting and Geotechnical Observation Prior to commencement of grading, we recommend a meeting be held between the developer, City Inspector, grading contractor, civil engineer, and geotechnical consultant to discuss the proposed grading and construction logistics. We also recommend a geotechnical consultant be retained to provide soil engineering and engineering geologic services during site grading and foundation construction. This is to observe compliance with the design specifications and recommendations and to allow for design changes in the event that subsurface conditions differ from those anticipated. If conditions are encountered that appear to be different than those indicated in this report, the project geotechnical consultant should be notified immediately. Design and construction revisions may be required. 6.1.3 Site Clearing Areas to be graded should be cleared of vegetation, existing asphalt, underground improvements to be abandoned and deleterious materials. Existing underground utility lines within the project area that will be protected in place and that fall within a 1 to 1 (H:V) plane projected down from the edges of footings may be subject to surcharge loads. Under such conditions, this office should be made aware of these conditions for evaluation of potential surcharging. Supplemental recommendations may be required to protect such improvements in place. The project geotechnical consultant should be notified at the appropriate times to provide observation services during clearing operations to verify compliance with the above recommendations. Voids created by clearing and excavation should be left open for observation by the geotechnical consultant. Should any unusual soil conditions or subsurface structures be encountered during site clearing or grading that are not described or anticipated herein, these conditions should be brought to the immediate attention of the project geotechnical consultant for corrective recommendations as needed. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 10 ALBUS & ASSOCIATES, INC. Temporary construction equipment (office trailers, power poles, etc.) should be positioned to allow adequate room for clearing and recommended ground preparation to be performed for proposed structures, pavements, and hardscapes. 6.1.4 Ground Preparation In general, the artificial fill is considered unsuitable for support of the proposed development. Artificial fill is estimated to typically be 2 feet thick. These materials should be removed from within the limits of residential structures and retaining walls. The removals should extend a minimum distance of 5 feet beyond the foundations. Artificial fill should also be removed below subgrade for pavement and screen walls. Such removals should extend at least 2 feet beyond the edges of pavement and footings where feasible. In addition to the general removal of existing fills, the alluvial soils should be over-excavated to a minimum depth of 1 foot below the bottoms of footings for the residential buildings. The actual depth of removal should be determined by the geotechnical consultant during grading. All removal excavations should be evaluated by the geotechnical consultant during grading to confirm the exposed conditions are as anticipated and to provide supplemental recommendations if required. The grading contractor should take appropriate measures when excavating adjacent any existing improvements to remain in-place to avoid disturbing or compromising support of existing structures. Following removals and overexcavation, the exposed grade should first be scarified to a depth of 6 inches, brought to at least 110 percent of the optimum moisture content, and then compacted to at least 90 percent of the laboratory standard (ASTM D 1557). 6.1.5 Fill Placement Materials excavated from the site may be reused as fill provided they are free of deleterious materials and particles greater than 6 inches in maximum dimension (oversized materials). Asphaltic and concrete debris generated during site demolition or encountered within the existing fill can be incorporated within new fill soils during earthwork operations provided they are reduced to no more than 4 inches in maximum dimension. Such materials should be mixed thoroughly with fill soils to prevent nesting. All fill should be placed in lifts no greater than 8 inches in loose thickness, moisture conditioned to at least the optimum moisture content, then compacted in place to at least 90 percent of the laboratory standard. Each lift should be treated in a similar manner. Subsequent lifts should not be placed until the project geotechnical consultant has approved the preceding lift. 6.1.6 Import Materials If import materials are required to achieve the proposed finish grades, the proposed import soils should have an Expansion Index (EI, ASTM D 4829) less than 21 and possess negligible soluble sulfate concentrations. Import sources should be indicated to the geotechnical consultant prior to hauling the materials to the site so that appropriate testing and evaluation of the fill materials can be performed in advance. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 11 ALBUS & ASSOCIATES, INC. 6.1.7 Temporary Excavations The upper 2 to 4 feet of site materials generally consist of silt sands that may be temporarily cut vertical up to a maximum height of 4 feet provided they are not surcharged. Temporary excavations greater than 4 feet or exposing friable sandy soils should be laid back at a maximum gradient of 1.5:1 (H:V) or properly shored. Excavations should not be left open for prolonged periods of time. The project geotechnical consultant should observe all temporary cuts to confirm anticipated conditions and to provide alternate recommendations if conditions dictate. All excavations should conform to the requirements of Cal/OSHA. Based on the anticipated removal depths discussed herein and the current minimum setback of 15 feet for buildings from property lines, we anticipate that removals can be accomplished with open cuts. However, if deeper removals are required during grading or final building locations are closer to property lines and thereby result in insufficient room for recommended lay back cuts, shoring may be required. Additional recommendations for such conditions can be provided after reviewing final site plans and during grading. 6.2 SEISMIC DESIGN PARAMETERS 6.2.1 Mapped Seismic Design Parameters For design of the project in accordance with Chapter 16 of the 2019 CBC, the mapped seismic parameters may be taken as presented in the tables below. TABLE 6.1 2019 CBC Mapped Seismic Design Parameters Parameter Value Site Class D Mapped MCER Spectral Response Acceleration, short periods, SS 1.997 Mapped MCER Spectral Response Acceleration, at 1-sec. period, S1 0.722 Site Coefficient, Fa 1.0 Site Coefficient, Fv 1.7* Adjusted MCER Spectral Response Acceleration, short periods, SMS 1.997 Adjusted MCER Spectral Response Acceleration, at 1-sec. period, SM1 1.227 Design Spectral Response Acceleration, short periods, SDS 1.331 Design Spectral Response Acceleration, at 1-sec. period, SD1 0.818 Long-Period Transition Period, TL (sec.) 8 Seismic Design Category for Risk Categories I-IV II MCER = Risk-Targeted Maximum Considered Earthquake *According to Section 11.4.8 in ASCE 7-16, “a ground motion hazard analysis shall be performed in accordance with Section 21.2 for the following structures on Site Class D and E sites with S1 greater than or equal to 0.2.” However, “A ground motion hazard analysis is not required for structures where: Structures on Site Class D sites with S1 greater than or equal to 0.2, provided the value of the seismic Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 12 ALBUS & ASSOCIATES, INC. response coefficient Cs is determined by Eq. (12.8-2) for values of T ≤ 1.5Ts and taken as equal to 1.5 times the value computed in accordance with either Eq. (12.8-3) for TL ≥ T > 1.5Ts or Eq. (12.8-4) for T > TL.” The Fv value of 1.7 above from Table 11.4-2 assumes that this exception is met and that a ground motion hazard analysis is not required. Should this exception not be met, the site-specific seismic design parameters provided in the next section should be used. 6.2.2 Site-Specific Seismic Design Parameters In addition to the Code Spectra parameters presented in Table 6.1, we have performed a site-specific ground motion hazard analysis in accordance with Chapter 21 of ASCE 7-16 to obtain site-specific seismic design acceleration parameters, the risk-targeted maximum considered earthquake response spectrum, and the design earthquake response spectrum. The site-specific seismic design parameters are presented below. TABLE 6.2 2019 CBC Site Specific Seismic Design Parameters Parameter Value Site Class D Site Coefficient, Fa 1.0 Site Coefficient, Fv 2.5 Adjusted MCE Spectral Response Acceleration, short periods, SMS 1.837 Adjusted MCE Spectral Response Acceleration, at 1-sec. period, SM1 1.444 Design Spectral Response Acceleration, short periods, SDS 1.225 Design Spectral Response Acceleration, at 1-sec. period, SD1 1.087 MCE = Maximum Considered Earthquake 6.3 CONVENTIONAL FOUNDATION DESIGN 6.3.1 General The following design parameters are provided to assist the project structural engineer to design foundations for structures at the site. These design parameters are based on typical site materials encountered during subsurface exploration and are provided for preliminary design and estimating purposes. The project geotechnical consultant should provide final design parameters following observation and testing of site materials during grading. Depending on actual materials encountered during site grading, the design parameters presented herein may require modification. 6.3.2 Soil Expansion The recommendations presented herein are based on soils with a Very Low expansion potential. Following site grading, additional testing of site soils should be performed by the project geotechnical consultant to confirm the basis of these recommendations. If site soils with higher expansion potentials are encountered or imported to the site, the recommendations contained herein may require modification. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 13 ALBUS & ASSOCIATES, INC. 6.3.3 Static and Seismic Settlement Based on anticipated foundation loads and provided that the recommendations for ground preparation in this report are followed, total and differential static settlement are anticipated to be less than 1 inch and ½ inch over 30 feet, respectively. These values are considered within tolerable limits of proposed structures and site improvements. Design of the structures should consider these maximum anticipated settlements. 6.3.4 Allowable Bearing Value Foundations may utilize a bearing value of 3,000 pounds per square foot (psf) for continuous and pad footings a minimum width of 12 inches and founded at a minimum depth of 12 inches below the lowest adjacent grade. This value may be increased by 300 psf and 800 psf for each additional foot in width and depth, respectively, up to a maximum value of 4,000 psf. Recommended allowable bearing values include both dead and live loads, and may be increased by one-third for wind and seismic forces. 6.3.5 Lateral Resistance A passive earth pressure of 250 pounds per square foot per foot of depth (psf/ft) up to a maximum value of 1,500 pounds per square foot (psf) may be used to determine lateral bearing for footings. This value may be increased by one-third when designing for wind and seismic forces. A coefficient of friction of 0.48 times the dead load forces may also be used between concrete and the supporting soils to determine lateral sliding resistance. No increase in the coefficient of friction should be used when designing for wind and seismic forces. The above values are based on footings placed directly against compacted fill or competent native soils. In the case where footing sides are formed, all backfill against the footings should be compacted to at least 90 percent of the laboratory standard. 6.3.6 Footing and Slab on Grade Exterior and interior building footings should be founded at a minimum depth of 12 inches and 12 inches, respectively, below the lowest adjacent grade. All continuous footings should be reinforced with a minimum of two No. 4 bars, one top and one bottom. The structural engineer may require different reinforcement and should dictate if greater than the recommendations provided herein. Interior isolated pad footings should be a minimum of 24 inches square and founded at minimum depths of 12 inches below the lowest adjacent final grade. Exterior isolated pad footings intended for support of patio covers or similar construction should be a minimum of 24 inches square and founded at a minimum depth of 12 inches below the lowest adjacent final grade. Interior concrete slabs constructed on grade should be a minimum 4 inches thick and should be reinforced with No. 3 bars spaced 30 inches on center, each way. Care should be taken to ensure the placement of reinforcement at mid-slab height. The structural engineer may recommend a greater slab thickness and reinforcement based on proposed use and loading conditions and such recommendations should govern if greater than the recommendations presented herein. Concrete floor slabs in areas to receive carpet, tile, or other moisture sensitive coverings should be underlain with a minimum of 10-mil moisture vapor retarder conforming to ASTM E 1745-11, Class Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 14 ALBUS & ASSOCIATES, INC. A. The membrane should be properly lapped, sealed, and underlain with at least 2 inches of sand having a SE no less than 30. One inch of this sand may be placed over the membrane to aid in the curing of the concrete. This vapor retarder system is anticipated to be suitable for most flooring finishes that can accommodate some vapor emissions. However, this system may emit more than 4 pounds of water per 1000 sq. ft. and therefore, may not be suitable for all flooring finishes. Additional steps should be taken if such vapor emission levels are too high for anticipated flooring finishes. Special consideration should be given to slabs in areas to receive ceramic tile or other rigid, crack- sensitive floor coverings. Design and construction of such areas should mitigate hairline cracking as recommended by the structural engineer. Garage floor slabs should have a minimum thickness of 4 inches and should be reinforced in a similar manner as living floor slabs. Garage floor slabs should also be poured separately from adjacent wall footings with a positive separation maintained with 3/8-inch minimum felt expansion joint materials, and provided with saw cuts or cold joints at a maximum spacing of 12 feet in each direction. Consideration should be given to providing a vapor retarder below the garage slab to mitigate the potential for effervescence on the slab surface. Block-outs should be provided around interior columns to permit relative movement and mitigate distress to the floor slabs due to differential settlement that will occur between column footings and adjacent floor subgrade soils as loads are applied. 6.3.7 Foundation Observations Foundation excavation should be observed by the project geotechnical consultant to verify that they have been excavated into competent bearing soils and to the minimum embedment recommended above. These observations should be performed prior to placement of forms or reinforcement. The excavations should be trimmed neat, level and square. Loose, sloughed or moisture-softened materials and debris should be removed prior to placing concrete. 6.4 RETAINING AND SCREENING WALLS 6.4.1 General The following preliminary design and construction recommendations are provided for general retaining and screen walls supported by engineered compacted fill or competent native soils. Final wall designs specific to the site development should be provided for review once completed. The structural engineer and architect should provide appropriate recommendations for sealing at all joints and applying moisture-proofing material on the back of the walls. 6.4.2 Allowable Bearing Value and Lateral Resistance Design of retaining and screen walls may utilize the bearing and lateral resistance values provided in Section 6.3.4 and 6.3.5. The passive earth pressure for walls along property lines, where lateral removals are likely restricted, should be reduced by 25%. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 15 ALBUS & ASSOCIATES, INC. 6.4.3 Active Earth Pressures Static and seismic earth pressures for level and 2:1 (H:V) backfill conditions are provided in Table 6.3. Seismic earth pressures provided herein are based on the method provided by Seed & Whitman (1970) using a peak ground acceleration (PGA) of 0.44 g for 10% probability of exceedance in 50 years. As indicated in Section 1803.5.12 of the 2019 CBC, retaining walls supporting 6 feet of backfill or less are not required to be designed for seismic earth pressures. The values provided in the following table do not consider hydrostatic pressure. Retaining walls should also be designed to support adjacent surcharge loads imposed by other nearby footings or traffic loads in addition to the earth pressure. 6.4.4 Drainage and Moisture-Proofing Retaining walls should be constructed with a perforated pipe and gravel subdrain to prevent entrapment of water in the backfill. The perforated pipe should consist of 4-inch-diameter, ABS SDR- 35 or PVC Schedule 40 with the perforations laid down. The pipe should be embedded in ¾- to 1½- inch open-graded gravel wrapped in filter fabric. The gravel should be at least one foot wide and extend at least one foot up the wall above the footing and drainage outlet. Drainage gravel and piping should not be placed below outlets and weepholes. Filter fabric should consist of Mirafi 140N, or equal. Outlet pipes should be directed to positive drainage devices. The use of weepholes may be considered in locations where aesthetic issues from potential nuisance water are not a concern. Weepholes should be 2 inches in diameter and provided at least every 6 feet on center. Where weepholes are used, perforated pipe may be omitted from the gravel subdrain. Retaining walls supporting backfill should also be coated with a moisture-proofing compound or covered with such material to inhibit infiltration of moisture through the walls. Moisture-proofing material should cover any portion of the back of wall that will be in contact with soil and should lap over and onto the top of footing. A drainage panel should be provided between the soil backfill and water proofing. The panel should extend from the top of the backdrain gravel up to within 12 inches of finish grade. The top of footing should be finished smooth with a trowel to inhibit the infiltration of water through the wall. The project structural engineer should provide specific recommendations for moisture-proofing, water stops, and joint details. 6.4.5 Foundation Observations Footing excavations should be observed by the project geotechnical consultant to verify that they have been excavated into competent bearing soils and to the minimum embedment recommended herein. These observations should be performed prior to placement of forms or reinforcement. The excavations should be trimmed neat, level and square. Loose, sloughed or moisture-softened materials and debris should be removed prior to placing concrete. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 16 ALBUS & ASSOCIATES, INC. TABLE 6.3 SEISMIC EARTH PRESSURES Pressure Diagram Static Seismic Total Component Component Force Pressure Values Walls Up To 10 Feet High Value Backfill Condition Level 2H:1V Slope A 28H 41H B 14H 14H C 21H 28H Note: H is in feet and resulting pressure is in psf. Design may utilize either the sum of the static component and the seismic component force diagrams or the total force diagram above. SEAOSC has suggested using a load factor of 1.7 for the static component and 1.0 for the seismic component. The actual load factors should be determined by the structural engineer. 6.5 EXTERIOR FLATWORK Concrete sidewalks, patios, and similar flatwork should be a nominal 4 inches thick and provided with saw cuts or expansion joints at spacing no greater than 10 feet in each direction. Special jointing details should be provided in areas of block-outs, notches, or other irregularities to avoid cracking at points of high stress. Drainage from flatwork areas should be directed to local area drains and/or other appropriate collection devices designed to carry runoff water to the street or other approved drainage structures. The concrete flatwork should also be sloped at a minimum gradient of 0.5 percent away from building foundations and retaining walls. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 17 ALBUS & ASSOCIATES, INC. Subgrade soils below flatwork should be thoroughly moistened to at least 100 percent of the optimum moisture content to a depth of 12 inches. Flooding or ponding of the subgrade is not recommended. Moistening should be accomplished by lightly spraying the area over a period of a few days just prior to pouring concrete. The geotechnical consultant should observe and verify the density and moisture content of subgrade soils prior to pouring concrete to ensure that the required compaction and pre- moistening recommendations have been met. 6.6 CONCRETE MIX DESIGN Laboratory testing of near-surface soils for soluble sulfate content indicates soluble sulfate concentration of 0.001%. We recommend following the procedures provided in ACI 318, Section 4.3, Table 4.3.1 for negligible sulfate exposure. Upon completion of rough grading, an evaluation of as- graded conditions and further laboratory testing should be completed for the site to confirm or modify the recommendations provided in this section. 6.7 CORROSION Results of preliminary testing of soils for pH, chloride, and minimum resistivity indicate the site is potentially Corrosive to metals that are in contact or close proximity to onsite soils. As such, specific recommendations should be obtained from a corrosion specialist if construction will include metals that will be near or in direct contact with site soils. 6.8 PRELIMINARY PAVEMENT DESIGN 6.8.1 Preliminary Pavement Structural Sections Based on the soil conditions present at the site and an estimated traffic index, preliminary pavement sections are provided in the table below. An assumed “R-value” of 30 was used for the near-surface soil in this preliminary pavement design. The sections provided below are for planning purposes only and should be re-evaluated subsequent to site grading. Final pavement sections should be based on actual R-value testing of in-place soils and analysis of anticipated traffic. TABLE 6.4 PRELIMINARY PAVEMENT STRUCTURAL SECTIONS Location Traffic Index AC (inches) Concrete Pavers (mm) PCC (inches) AB (inches) Entry Way and Drives 5.5 3.0 4.0 -- -- 8.0 5.0 -- -- 6.5 -- -- 80.0 -- 8.0 Parking Stalls -- 3.0 -- -- 4.0 Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 18 ALBUS & ASSOCIATES, INC. 6.8.2 Subgrade Preparation Prior to placement of paving elements, subgrade soils should be scarified 6 inches, moisture- conditioned to above the optimum moisture content then compacted to at least 90 percent of the maximum dry density determined in accordance with ASTM D1557. Areas observed to pump or yield under vehicle traffic should be removed and replaced with firm and unyielding engineered compacted soil or aggregate base materials. 6.8.3 Aggregate Base Aggregate base materials should be Crushed Aggregate Base or Crushed Miscellaneous Base conforming to Section 200-2 of the Standard Specification for Public Works Construction (Greenbook) or Class 2 Aggregate Base conforming to the Caltrans’ Standard Specifications. The materials should be moisture conditioned to slightly over the optimum moisture content then compacted to at least 95 percent of ASTM D 1557. 6.8.4 Asphaltic Concrete Paving asphalt should be PG 64-10 conforming to the requirements of Section 203-1 of the Greenbook. Asphalt concrete materials should conform to Section 203-6 and construction should conform to Section 302 of the Greenbook. 6.8.5 Concrete Paver Concrete pavers should conform to the requirements of ASTM C 936. Construction of the pavers, including bedding sand, should follow manufacturer’s specifications. Typical thickness of bedding sand is about 1 inch. The gradation of bedding sand should meet the requirement in Table 6.5. TABLE 6.5 Gradation for Sand Bedding Sieve Size Percent Passing ⅜” 100 No. 4 95 - 100 No. 8 80 - 100 No. 16 50 - 85 No. 30 25 - 60 No. 50 5 - 30 No. 100 0 - 10 No. 200 0 - 1 6.8.6 Portland Cement Concrete Portland cement concrete used to construct concrete paving should conform to Section 201 of the Greenbook and should have a minimum compressive strength of 3,250 pounds per square inch (psi) at 28 days. Reinforcement and jointing of concrete pavement sections should be designed according to the minimum recommendations provided by the Portland Cement Association (PCA). For rigid pavement, transverse and longitudinal contraction joints should be provided at spacing no greater than 15 feet. Score joints may be constructed by saw cutting to a depth of ¼ of the slab thickness. Expansion/cold joints may be used in lieu of score joints. Such joints should be properly sealed. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 19 ALBUS & ASSOCIATES, INC. Where traffic will traverse over cold joints without keyways or dowels or edges of concrete paving, the edges should be thickened by 20% of the design thickness toward the edge over a horizontal distance of 5 feet. 6.9 POST GRADING CONSIDERATIONS 6.9.1 Site Drainage and Irrigation The ground immediately adjacent to foundations should be provided with positive drainage away from the structures in accordance with 2019 CBC, Section 1804.4. However, the slope of the ground surface may be reduced to 2% based on climatic and soil conditions. No rain or excess water should be allowed to pond against structures such as walls, foundations, flatwork, etc. Excessive irrigation water can be detrimental to the performance of the proposed site development. Water applied in excess of the needs of vegetation will tend to percolate into the ground. Such percolation can lead to nuisance seepage and shallow perched groundwater. Seepage can form on slope faces, on the faces of retaining walls, in streets, or other low-lying areas. These conditions could lead to adverse effects such as the formation of stagnant water that breeds insects, distress or damage of trees, surface erosion, slope instability, discoloration and salt buildup on wall faces, and premature failure of pavement. Excessive watering can also lead to elevated vapor emissions within buildings that can damage flooring finishes or lead to mold growth inside the home. Key factors that can help mitigate the potential for adverse effects of overwatering include the judicious use of water for irrigation, use of irrigation systems that are appropriate for the type of vegetation and geometric configuration of the planted area, the use of soil amendments to enhance moisture retention, use of low-water demand vegetation, regular use of appropriate fertilizers, and seasonal adjustments of irrigation systems to match the water requirements of vegetation. Specific recommendations should be provided by a landscape architect or other knowledgeable professional. 6.9.2 Utility Trenches Trench excavations should be constructed in accordance with the recommendations contained in Section 6.1.7 of this report. Trench excavations must also conform to the requirements of Cal/OSHA. Trench backfill materials and compaction criteria should conform to the requirements of the local municipalities. As a minimum, utility trench backfill should be compacted to at least 90 percent of the laboratory standard. Materials placed within the pipe zone (6 inches below and 12 inches above the pipe) should consist of particles no greater than ¾ inches and have a SE of at least 30. The materials within the pipe zone should be moisture-conditioned and compacted by hand-operated compaction equipment. Above the pipe zone (>1 foot above pipe), the backfill may consist of general fill materials. Trench backfill should be moisture-conditioned to slightly over the optimum moisture content, placed in lifts no greater than 12 inches in thickness, and then mechanically compacted with appropriate equipment to at least 90 percent of the laboratory standard. For trenches with sloped walls, backfill material should be placed in lifts no greater than 8 inches in loose thickness, and then compacted by rolling with a sheepsfoot roller or similar equipment. The project geotechnical consultant should perform density testing along with probing to verify that adequate compaction has been achieved. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 20 ALBUS & ASSOCIATES, INC. Within shallow trenches (less than 18 inches deep) where pipes may be damaged by heavy compaction equipment, imported clean sand having a SE of 30 or greater may be utilized. The sand should be placed in the trench, thoroughly watered, and then compacted with a vibratory compactor. For utility trenches located below a 1:1 (H:V) plane projecting downward from the outside edge of the adjacent footing base or crossing footing trenches, concrete or slurry should be used as trench backfill. 6.10 PLAN REVIEW AND CONSTRUCTION SERVICES We recommend Albus & Associates, Inc. be engaged to review any future development plans, including civil plans (grading plans), foundation plans, and proposed structural loads, prior to construction. This is to verify that the assumptions of this report are valid and that the preliminary conclusions and recommendations contained in this report have been properly interpreted and are incorporated into the project plans and specifications. If we are not provided the opportunity to review these documents, we take no responsibility for misinterpretation of our preliminary conclusions and recommendations. We recommend that a geotechnical consultant be retained to provide soil engineering services during construction of the project. These services are to observe compliance with the design, specifications or recommendations, and to allow design changes in the event that subsurface conditions differ from those anticipated prior to the start of construction. If the project plans change significantly from the assumed development described herein, the project geotechnical consultant should review our preliminary design recommendations and their applicability to the revised construction. If conditions are encountered during construction that appear to be different than those indicated in this report or subsequent design reports, the project geotechnical consultant should be notified immediately. Design and construction revisions may be required. 7.0 LIMITATIONS This report is based on the proposed development and geotechnical data as described herein. The materials encountered on the project site and utilized in our laboratory testing for this investigation are believed representative of the total 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. This report has been prepared consistent with that 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 guaranty or warranty. This report should be reviewed and updated after a period of one year or if the site ownership or project concept changes from that described herein. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 21 ALBUS & ASSOCIATES, INC. This report has been prepared for the exclusive use of Borstein Enterprises and their project consultants in the planning and design of the proposed development. This report has not been prepared for use by parties or projects other than those named or described herein. This report may not contain sufficient information for other parties or other purposes. This report is subject to review by the controlling governmental agency. Respectfully submitted, ALBUS & ASSOCIATES, INC. Eung Jin Jeon, Ph.D. David E. Albus Associate Engineer Principal Engineer G.E. 3097 G.E. 2455 Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 22 ALBUS & ASSOCIATES, INC. 8.0 REFERENCES Publications Abrahamson, N.A., Silva, W.J., and Kamai, R. 2014., “Update of the AS08 Ground-Motion Prediction Equations Based on the NGA-West2 Data Set.” Earthquake Spectra 30 (3): 1179-1197. American Society of Civil Engineers, 2017, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, ASCE 7-16. Boore, D.M., Stewart, J.P., Seyhan, E., and Atkinson, G.M., 2014. “NGA-West2 Equations for Predicting PGA, PGV, and 5% damped PSA for Shallow Crustal Earthquakes.” Earthquake Spectra 30 (3): 1057-1085. Dibblee, T.W., Jr. 1999. Geologic map of the El Monte and Baldwin Park quadrangles, Los Angeles, California: Dibblee Geological Foundation, Map DF-69, scale 1:24,000. California Geologic Survey, 2008. Guidelines for Evaluating and Mitigating Seismic Hazards in California, Special Publication 117A. California Department of Conservation, Division of Mines and Geology, 1998. “Seismic Hazard Zone Report for the Whittier 7.5-Minute Quadrangle, Los Angles and Orange Counties, California.” Seismic Hazard Report 037. Campbell, K.W., and Bozorgnia, Y., 2014. “NGA-West2 Ground Motion Model for the Average Horizontal Components of PGA, PGV, and 5%-damped Linear Acceleration Response Spectra.” Earthquake Spectra 30 (3): 1087-1115. Chiou, B.S.-J., and Youngs, R.R., 2014. “Update of the Chiou and Youngs NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra, Earthquake Spectra, 30 (3): 1117-1153. Field, E.H., Biasi, G.P., Bird, P., Dawson, T.E., Felzer, K.R., Jackson, D.D., Johnson, K.M., Jordan, T.H., Madden, C., Michael, A.J., Milner, K.R., Page, M.T., Parsons, T., Powers, P.M., Shaw, B.E., Thatcher, W.R., Weldon, R.J., II, and Zeng, Y., 2013, Uniform California earthquake rupture forecast, version 3 (UCERF3)—The time-independent model: U.S. Geological Survey Open-File Report 2013–1165, 97 p., California Geological Survey Special Report 228, and Southern California Earthquake Center Publication 1792, http://pubs.usgs.gov/of/2013/1165/. Los Angeles County Department of Public Works Well Data (accessed 2020): https://dpw.lacounty.gov/general/wells/ Seed, H.B., and Whitman, R.V., 1970. “Design of Earth Retaining Structures for Dynamic Loads,” ASCE Specialty Conference, Lateral Stresses in the Ground and Design of Earth Retaining Structures, Cornell Univ., Ithaca, New York, 103-147. Borstein Enterprises October 27, 2021 J.N.: 3016.00 Page 23 ALBUS & ASSOCIATES, INC. REFERENCES (cont.) Youd, T.L., Idriss, I.M., Andrus, R.D., Arango, I., Castro, G., Christian, J., Dobry, R., Finn, W.D.L., Harder, L.F., Hynes, M.E., Ishihara, K., Koester, J.P., Liao, S.S.C., Marcuson, W.F., Martin, G.R., Mitchell, J.K., Moriwaki, Y., Power, M.S., Robertson, P.K., Seed, R.B., and Stokoe, K.H. 2001. “Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils.” ASCE Journal of Geotechnical and Geoenvironmental Engineering 127 (10): 817-833. APPROXIMATEPROJECT SITE LIMITSB-1P-2P-1B-2B-3B-4B-5B-6EXPLANATION(Locations Approximate)0 50 100 200APPROX SCALE : 1" = 100'- Exploratory Boring- Percolation Test Boring1Plate:Date: 10/27/20213016.00Job No.:GEOTECHNICAL MAP©Google 2021 ALBUS & ASSOCIATES, INC. APPENDIX A EXPLORATION LOGS Field Identification Sheet Light gray Description Order: Description, Color, Moisture, Density, Grain Size, Additional Description Gray Description % 0-5 trace 5-15 Dark gray with 15-30 30+Gravelly Sand with Silt trace Clay Moisture Silty Clay with Sand trace Gravel Gray Brown Dry Damp Moist Light brown Very Moist Wet Brown Density (Navfac) SPT CA 0-3 0-5 Dark Brown 3-8 5-13 8-14 13-22 14-25 22-40 Olive brown 25> 40> 2< 0-3 Olive 2-4 3-6 4-8 6-13 8-15 13-24 Yellow 15-30 24-48 30> 48> Yellowish brown Grain Size Description Sieve Size Approx. Size >12" Larger than basketball Yellowish red 3-12" Fist to basketball coarse 3/4-3" Thumb to Fist fine #4-3/4" Pea to Thumb Red coarse #10-4 Rock Salt to Pea medium #40-10 Sugar to Rock Salt fine #200-40 Flour to Sugar Reddish Brown Pass #200 Smaller than Flour Additional Description (ie. roots, pinhole pores, debris, etc.) Tan Trace 5% Moderate 15% Abundant 30% Albus & Associates, Inc. Plate A-0 absence of water near optimum below optimum Very Loose Sand Sand trace Silt Sand with Silt Silty Sand Example Very Soft Soft Stiff above optimum free water visible Loose Medium Dense More Examples Fines Sand Gravel Sand with Silt and Clay Sand trace Silt and Clay Sand with Silt trace Clay Very Stiff Hard Fine grained soils Medium Stiff Boulders Cobbles Dense Coarse grained soils Very Dense Project: Address: Job Number: Drill Method: Client: Driving Weight: Location: Elevation: Date: Logged By: Depth (feet) Lith- ology Blows Per Foot Moisture Content (%) Dry Density (pcf) Other Lab Tests Laboratory TestsSamples Material Description E X P L O R A T I O N L O G WaterCoreBulk5 10 15 20 EXPLANATION Solid lines separate geologic units and/or material types. Dashed lines indicate unknown depth of geologic unit change or material type change. Solid black rectangle in Core column represents California Split Spoon sampler (2.5in ID, 3in OD). Double triangle in core column represents SPT sampler. Vertical Lines in core column represents Shelby sampler. Solid black rectangle in Bulk column respresents large bag sample. Other Laboratory Tests: Max = Maximum Dry Density/Optimum Moisture Content EI = Expansion Index SO4 = Soluble Sulfate Content DSR = Direct Shear, Remolded DS = Direct Shear, Undisturbed SA = Sieve Analysis (1" through #200 sieve) Hydro = Particle Size Analysis (SA with Hydrometer) 200 = Percent Passing #200 Sieve Consol = Consolidation SE = Sand Equivalent Rval = R-Value ATT = Atterberg Limits Albus & Associates, Inc.Plate A-1 Project: Address: Job Number: Drill Method: Client: Driving Weight: Location: Elevation: Date: Logged By: Depth (feet) Lith- ology Blows Per Foot Moisture Content (%) Dry Density (pcf) Other Lab Tests Laboratory TestsSamples Material Description E X P L O R A T I O N L O G 8601 Mission Dr, Rosemead, CA 3016.00 9/7/2021 ddalbusHollow-Stem Auger Borstein Enterprises B-1 358 WaterCoreBulk140 lbs / 30 in 5 10 15 20 25 ARTIFICIAL FILL (Af) Silty Sand (SM):Light brown, dry, fine to medium grained sand ALLUVIUM (Qal) Sand with Gravel trace Silt (SP):Brown to yellowish brown, damp, medium dense, fine to coarse grained sand Sand with Gravel (SP):Yellowish brown, damp to moist, medium dense, fine to coarse grained sand Gravelly Sand (SW):Yellowish brown, damp to moist, medium dense, fine to coarse grained sand @ 10 ft, more coarse grained sand @ 15 ft, dry to damp, very dense Silty Sand (SM):Brown to yellowish brown, moist, very dense, fine grained sand @ 20 ft, medium dense Sand with Gravel trace Silt (SP):Brown, moist, dense, more fine grained sand 34 37 17 10 21 20 28 3.6 2.9 3.2 2.6 117.4 112.4 103.9 112.8 Max EI SO4 DS pH Resist Ch SA Hydro 200 Albus & Associates, Inc.Plate A-2 Project: Address: Job Number: Drill Method: Client: Driving Weight: Location: Elevation: Date: Logged By: Depth (feet) Lith- ology Blows Per Foot Moisture Content (%) Dry Density (pcf) Other Lab Tests Laboratory TestsSamples Material Description E X P L O R A T I O N L O G 8601 Mission Dr, Rosemead, CA 3016.00 9/7/2021 ddalbusHollow-Stem Auger Borstein Enterprises B-1 358 WaterCoreBulk140 lbs / 30 in 35 40 45 50 Yellowish brown, very dense, more fine to coarse grained sand Gravelly Sand (SP):Light reddish brown, dry to damp, very dense, fine to coarse grained sand Sand with Silt (SP):Light reddish brown, damp to moist, very dense, fine grained sand Silty Sand (SM):Light reddish brown, damp to moist, very dense, fine grained sand, moderate fines Clayey Sand (SC):Brown to reddish brown, moist, hard, fine grained sand Total Depth 51.5 feet No Groundwater Boring backfilled with soil cuttings 52 49 36 61 30 SA Hydro 200 200 ATT Albus & Associates, Inc.Plate A-3 Project: Address: Job Number: Drill Method: Client: Driving Weight: Location: Elevation: Date: Logged By: Depth (feet) Lith- ology Blows Per Foot Moisture Content (%) Dry Density (pcf) Other Lab Tests Laboratory TestsSamples Material Description E X P L O R A T I O N L O G 8601 Mission Dr, Rosemead, CA 3016.00 9/7/2021 ddalbusHollow-Stem Auger Borstein Enterprises B-2 357.9 WaterCoreBulk140 lbs / 30 in 5 10 ARTIFICIAL FILL (Af) Silty Sand (SM): Brown, dry, fine grained sand ALLUVIUM (Qal) Silty Sand with Gravel (SM): Brown, damp, medium dense, fine to coarse grained sand Gravelly Sand (SP): Yellowish brown, moist, medium dense, fine to coarse grained sand @ 6 ft, dense, gravel up to 1 inch dia @ 10 ft, medium dense, cobbles observed in cuttings up to 6 inch dia Total Depth 11.5 feet No Groundwater Boring backfilled with soil cuttings 15 28 25 30 2.7 3.3 112.4 200 Albus & Associates, Inc.Plate A-4 Project: Address: Job Number: Drill Method: Client: Driving Weight: Location: Elevation: Date: Logged By: Depth (feet) Lith- ology Blows Per Foot Moisture Content (%) Dry Density (pcf) Other Lab Tests Laboratory TestsSamples Material Description E X P L O R A T I O N L O G 8601 Mission Dr, Rosemead, CA 3016.00 9/7/2021 ddalbusHollow-Stem Auger Borstein Enterprises B-3 357.9 WaterCoreBulk140 lbs / 30 in 5 10 ARTIFICIAL FILL (Af) Silty Sand (SM): Brown, dry, fine grained sand ALLUVIUM (Qal) Gravelly Sand trace Silt (SP): Yellowish brown, dry to damp, medium dense, fine to coarse grained sand @ 4 ft, damp, loose, no silt, gravel up to 1 inch dia @ 6 ft, moist, medium dense @ 10 ft, 4 inch dia cobble observed in cuttings Total Depth 11.5 feet No Groundwater Boring backfilled with soil cuttings 19 12 27 2.3 3.1 3.4 104.9 109.8 Consol Albus & Associates, Inc.Plate A-5 Project: Address: Job Number: Drill Method: Client: Driving Weight: Location: Elevation: Date: Logged By: Depth (feet) Lith- ology Blows Per Foot Moisture Content (%) Dry Density (pcf) Other Lab Tests Laboratory TestsSamples Material Description E X P L O R A T I O N L O G 8601 Mission Dr, Rosemead, CA 3016.00 9/7/2021 ddalbusHollow-Stem Auger Borstein Enterprises B-4 358 WaterCoreBulk140 lbs / 30 in 5 10 ARTIFICIAL FILL (Af) Silty Sand (SM): Brown, dry, fine grained sand ALLUVIUM (Qal) Silty Sand with Gravel (SM): Brown, moist, loose, fine to coarse grained sand Sand with Gravel (SP): Yellowish brown, moist, loose, fine to coarse grained sand @ 6 ft, medium dense @ 10 ft, more coarse grained sand Total Depth 11.5 feet No Groundwater Boring backfilled with soil cuttings 31 15 13 17 3.7 3.8 2.8 4.5 112.9 107.2 105.9 Consol Albus & Associates, Inc.Plate A-6 Project: Address: Job Number: Drill Method: Client: Driving Weight: Location: Elevation: Date: Logged By: Depth (feet) Lith- ology Blows Per Foot Moisture Content (%) Dry Density (pcf) Other Lab Tests Laboratory TestsSamples Material Description E X P L O R A T I O N L O G 8601 Mission Dr, Rosemead, CA 3016.00 9/7/2021 ddalbusHollow-Stem Auger Borstein Enterprises B-5 361 WaterCoreBulk140 lbs / 30 in 5 10 ARTIFICIAL FILL (Af) Silty Sand (SM): Brown, dry, fine grained sand ALLUVIUM (Qal) Silty Sand with Gravel (SM): Brown, damp, medium dense, fine to medium grained sand @ 4 ft, Yellowish brown Sand with Gravel (SP): Yellowish brown, moist, medium dense, fine to coarse grained sand Total Depth 11.5 feet No Groundwater Boring backfilled with soil cuttings 17 20 34 3.4 4.6 3.1 108.7 -31.3 111.1 200 Albus & Associates, Inc.Plate A-7 Project: Address: Job Number: Drill Method: Client: Driving Weight: Location: Elevation: Date: Logged By: Depth (feet) Lith- ology Blows Per Foot Moisture Content (%) Dry Density (pcf) Other Lab Tests Laboratory TestsSamples Material Description E X P L O R A T I O N L O G 8601 Mission Dr, Rosemead, CA 3016.00 9/7/2021 ddalbusHollow-Stem Auger Borstein Enterprises B-6 361.2 WaterCoreBulk140 lbs / 30 in 5 10 ARTIFICIAL FILL (Af) Silty Sand (SM): Brown, dry, fine grained sand ALLUVIUM (Qal) Silty Sand with Gravel (SM): Brown, damp, medium dense, fine to coarse grained sand Gravelly Sand (SP): Yellowish brown, damp, loose, fine to coarse grained sand @ 6 ft, medium dense, more coarse grained sand @ 10 ft, dense, more gravel 46 16 15 24 3.4 2.1 2.4 2.4 103.2 108.5 109.8 200 Albus & Associates, Inc.Plate A-8 Total Depth 11.5 feet No Groundwater Boring backfilled with soil cuttings ALBUS & ASSOCIATES, INC. APPENDIX B LABORATORY TEST RESULTS Borstein Enterprises October 27, 2021 J.N.: 3016.00 ALBUS & ASSOCIATES, INC. LABORATORY TESTING PROGRAM Soil Classification Soils encountered within the exploratory borings were initially classified in the field in general accordance with the visual-manual procedures of the Unified Soil Classification System (ASTM D 2488). The samples were re-examined in the laboratory and classifications reviewed and then revised where appropriate. The assigned group symbols are presented on the Exploration Logs provided in Appendix A. In-Situ Moisture Content and Dry Density Moisture content and dry density of in-place soil materials were determined in representative strata. Test data are summarized on the Exploration Logs, Appendix A. Maximum Dry Density and Optimum Moisture Content Maximum dry density and optimum moisture content were performed on a representative sample of the site materials obtained from our field explorations. The test was performed in accordance with ASTM D 1557. Pertinent test values are given in Table B-1. Expansion Potential Expansion index testing was performed on a selected sample. The test was performed in accordance with ASTM D4829. The test result and expansion potential are presented on Table B-1. Soluble Sulfate Content A chemical analysis was performed on a selected sample to determine soluble sulfate content. This test was performed in our soil laboratory in accordance with California Test Method No 417. The test result is included on Table B-1. Atterberg Limits Atterberg Limits (Liquid Limit, Plastic Limit, and Plasticity Index) were performed in accordance with Test Method ASTM D 4318. Pertinent test values are presented within Table B-1. Particle Size Analyses Particle size analyses were performed on representative samples of site materials in accordance with ASTM D 422. The results are presented graphically on the attached Plates B-1 and B-2. Direct Shear The Coulomb shear strength parameters, angle of internal friction and cohesion, were determined for a bulk sample and intact samples obtained from one our borings. The tests were performed in general conformance with Test Method ASTM D 3080. The bulk sample was remolded to 90 percent of maximum dry density and at the optimum moisture content. Three specimens were prepared for each test, artificially saturated, and then sheared under varied loads at an appropriate constant rate of strain. Results are graphically presented on Plate B-3. Borstein Enterprises October 27, 2021 J.N.: 3016.00 ALBUS & ASSOCIATES, INC. Corrosion Select samples were tested for minimum resistivity, chloride, pH in accordance with California Test Method 643. Results of these tests are provided in Table B-1. TABLE B-1 SUMMARY OF LABORATORY TEST RESULTS Boring No. Sample Depth (ft) Soil Description Test Results B-1 0-5 Silty Sand with Gravel Max. Dry Density (pcf): Opt. Moisture Content (%): Expansion Index: Expansion Potential: Soluble Sulfate Content: Sulfate Exposure: PH: Chloride content (ppm): Resistivity (ohms): 132.5 6.5 0 Very Low 0.005% Negligible 6.86 75 3900 B-1 20 Silty Sand Passing No. 200 Sieve: 43.4 B-1 35 Gravelly Sand trace Silt Passing No. 200 Sieve: 11.1 B-1 45 Sand with Silt Passing No. 200 Sieve: 17.7 B-1 50 Sandy Clay with Silt Liquid Limit (%): Plasticity Index (%): 25 7.2 B-2 10 Gravelly Sand trace Silt Passing No. 200 Sieve: 10.7 B-5 10 Gravelly Sand with Silt Passing No. 200 Sieve: 20.3 B-6 4 Sand trace Silt Passing No. 200 Sieve: 6.2 Note: Additional laboratory test results are provided on the boring logs provided in Appendix A. COARSE FINE COARSE MEDIUM FINE Description Sand with Gravel trace Silt Albus & Associates, Inc.Plate B-1 3016.00 GRAIN SIZE DISTRIBUTION Job Number Location B-1 GRAVELCOBBLES SILT AND CLAYSAND 15 Depth 6"3"1.5"3/4"3/8"4 10 20 40 60 100 200 0 10 20 30 40 50 60 70 80 90 1000 10 20 30 40 50 60 70 80 90 100 0.00010.0010.010.1110100 U.S. Standard Sieve Sizes Percent RetainedPercent PassingGrain Size in Millimeters COARSE FINE COARSE MEDIUM FINE Description Sand with Gravel trace Silt Albus & Associates, Inc.Plate B-2 3016.00 GRAIN SIZE DISTRIBUTION Job Number Location B-1 GRAVELCOBBLES SILT AND CLAYSAND 30 Depth 6"3"1.5"3/4"3/8"4 10 20 40 60 100 200 0 10 20 30 40 50 60 70 80 90 1000 10 20 30 40 50 60 70 80 90 100 0.00010.0010.010.1110100 U.S. Standard Sieve Sizes Percent RetainedPercent PassingGrain Size in Millimeters CONSOLIDATION Job Number Location Depth 3016.00 B-3 6 Albus & Associates, Inc.Plate B-3 Description Sand 102.5 4 18.2 Initial Dry Density (pcf)Initial Moisture Content (%)Final Moisture Concent (%) 0 1 2 3 4 5 6 7 8 9 10 11 12 100 1000 10000 100000CONSOLIDATION (%)NORMAL STRESS (psf) Field Saturated CONSOLIDATION Job Number Location Depth 3016.00 B-4 6 Albus & Associates, Inc.Plate B-4 Description Sand 106.5 4.9 18.7 Initial Dry Density (pcf)Initial Moisture Content (%)Final Moisture Concent (%) 0 1 2 3 4 5 6 7 8 9 10 11 12 100 1000 10000 100000CONSOLIDATION (%)NORMAL STRESS (psf) Field Saturated DIRECT SHEAR Sample Type: Normal Stress (ksf)1 2 4 Peak Shear Stress (ksf)0.924 2.256 4.416 Peak Displacement (in)0.02 0.022 0.023 Ultimate Shear Stress (ksf)0.552 1.704 3.408 Ultimate Displacement (in)0.24 0.25 0.25 Initial Dry Density (pcf)124.5 124.5 124.5 Initial Moisture Content (%)2 2 2 Final Moisture Content (%)7.2 7.1 6.7 Strain Rate (in/min) Job Number Location Depth 3016.00 B-1 0-5 Albus & Associates, Inc.Plate B-5 Description Silty Sand with Gravel 0.05 Saturated, Remolded -0.005 0 0.005 0.01 0.015 0.02 0.025 0 2 4 6 8 10 Vertical Displacement (in)Strain (%) 1 2 4 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 2 4 6 8 10 Shear Stress (ksf)Strain (%) 1 2 4 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5SHEAR STRESS (ksf)NORMAL STRESS (ksf) Peak Ultimate Linear (Peak) Linear (Ultimate)