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HomeMy WebLinkAboutCDP 2022-0067; LABOUNTY RESIDENCE - 3950; REVISED REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION; 2024-07-01 REVISED REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION LaBounty Residences 3940 and 3950 Garfield Street Carlsbad, California JOB NO. 23-14188 01 July 2024 Prepared for: Judith and Paul LaBounty 01 July 2024 Judith and Paul LaBounty Job No. 23-14188 3950 Garfield Street Carlsbad, CA 92011 Subject: Revised Report of Preliminary Geotechnical Investigation LaBounty Residences 3940 and 3950 Garfield Street Carlsbad, California Dear Mr. and Mrs. LaBounty: In accordance with our proposal and work agreement dated January 17, 2023, Geotechnical Exploration, Inc. has performed a preliminary geotechnical investigation for the subject projects in San Marcos, California. The field work was performed on March 13, 2023. If the conclusions and recommendations presented in this report are incorporated into the design and construction, it is our opinion that the sites are suitable for the proposed new residences and associated improvements from a geotechnical perspective. This opportunity to be of service is sincerely appreciated. Should you have any questions concerning the following report, please do not hesitate to contact us. Reference to our Job No. 23-14188 will expedite a response to your inquiries. Respectfully submitted, GEOTECHNICAL EXPLORATION, INC. _______________________________ ______________________________ Wm. D. Hespeler, G.E. 396 Jay K. Heiser Senior Geotechnical Engineer Senior Project Geologist TABLE OF CONTENTS I. PROJECT SUMMARY 1 II. SCOPE OF WORK 2 III. SITE DESCRIPTION 2 IV. FIELD INVESTIGATION 3 V. LABORATORY TESTS AND SOIL INFORMATION 3 VI. SITE-SPECIFIC SOIL & GEOLOGIC DESCRIPTION 5 A. Stratigraphy 5 B. Structure 6 VII. GEOLOGIC HAZARDS 6 VIII. GROUNDWATER 7 IX. CONCLUSIONS AND RECOMMENDATIONS 8 A. Site Preparation and Earthwork 9 B. Foundation Recommendations 13 C. Concrete Slab On-grade Criteria 16 D. General Recommendations 20 X. GRADING NOTES 22 XI. LIMITATIONS 22 FIGURES I. Vicinity Map II. Plot Plan and Site-Specific Geologic Map IIIa-d. Exploratory Test Pit Logs IV. Geologic Map Excerpt and Legend APPENDICES A. Unified Soil Classification System B. Soluble Sulfate and Chloride Test Results REVISED REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION LaBounty Residences 3940 and 3950 Garfield Street Carlsbad, California JOB NO. 23-14188 The following report presents the findings and recommendations of Geotechnical Exploration, Inc. for the subject project. I. PROJECT SUMMARY It is our understanding that the residences on the two adjacent lots (APN Nos. 206- 012-05-00 and 206-012-06-00) will be removed and each lot will be developed to receive a new three-story, single-family residence with attached two-car garage and associated improvements. The new structures are to be constructed of standard- type building materials and foundation loads are expected to be typical for this type of relatively light construction. Flooring is to be concrete slab on-grade. When final architectural and engineering plans have been prepared, they should be made available for our review. Additional or modified recommendations would be provided at that time if warranted. Please be aware that the importance of thorough observation and testing during construction should be recognized by the client and the contractor(s) to provide appropriate documentation for any necessary as-graded reports. Recommendations for observation and testing are provided under Conclusions and Recommendations No. 7, “Observations and Testing.” Based on our current understanding of the proposed construction, it is our opinion that construction of the proposed new residences would not destabilize neighboring properties or induce the settlement of adjacent structures if designed and constructed in accordance with our recommendations. LaBounty Residences Job No. 23-14188 Carlsbad, California Page 2 II. SCOPE OF WORK The scope of work performed for this investigation included a site reconnaissance and subsurface exploration program under the direction of our geologist with the placement, logging and sampling of three exploratory test pits across the lots utilizing hand tools, review of available published literature pertaining to the site geology, laboratory testing of sampled soils, geotechnical engineering analysis of the field and laboratory data, and the preparation of this report. The data obtained and the analyses performed were for the purpose of providing design and construction criteria for the project earthwork, seismic design, building foundations, slab on-grade floors, and associated improvements. III. SITE DESCRIPTION The subject lots are known as Assessor’s Parcel Nos. 206-012-05-00 and 206-012- 06-00. Refer to Figure No. I, the Vicinity Map, for the site location. The rectangular- shaped lots are each 6,000 square feet in size. Each lot is currently occupied by an existing residential structure that will be demolished. The lots are bordered on the west by Garfield Street at about the same elevation, and on the north, east and south by existing residences at about the same elevation. Vegetation across the site consists of ornamental landscaping with some shrubs and a few mature trees. The elevation of the lots is approximately 69 feet above Mean Sea Level (MSL) on the west property line adjacent to Garfield Street, and both lots slope gently down to about 64 feet above MSL at the rear of each lot. LaBounty Residences Job No. 23-14188 Carlsbad, California Page 3 IV. FIELD INVESTIGATION The field investigation consisted of a surface reconnaissance and a subsurface exploration program utilizing hand tools to investigate and sample the subsurface soils. Four exploratory test pits (two on each lot) were advanced on the lots on March 13, 2023. The exploratory test pits were advanced to depths of 5 to 7 feet to obtain representative soil samples and to define the soil profile in the project area. The materials encountered in the exploratory test pits were continuously logged in the field by our geologist and described in accordance with the Unified Soil Classification System (refer to Appendix A). The approximate locations of the exploratory test pits are shown on the attached Plot Plan and Site-Specific Geologic Map, Figure No. II. A relatively undisturbed sample obtained by driving a lined sample barrel and a bulk sample were collected from the exploratory test pits to aid in classification and for appropriate laboratory testing. The samples were returned to our laboratory for evaluation and testing. Exploratory test pit logs were prepared on the basis of our observations and laboratory test results and are attached as Figure Nos. IIIa-d. The exploratory test pit logs and related information depict subsurface conditions only at the specific locations shown on the plot plan and on the particular date designated on the logs. Subsurface conditions at other locations may differ from conditions occurring at these locations. Also, the passage of time may result in changes in the subsurface conditions due to environmental changes. V. LABORATORY TESTS AND SOIL INFORMATION Laboratory tests were performed on retrieved soil samples in order to evaluate their physical and mechanical properties. The test results are presented on the test pit LaBounty Residences Job No. 23-14188 Carlsbad, California Page 4 logs, Figure No. IIIa-d, at the appropriate sample depths. The following tests were conducted on representative soil samples: 1. Moisture Content (ASTM D2216-19) 2. Laboratory Compaction Characteristics (ASTM D1557-12[2021]) 3. Determination of Percentage of Particles Smaller than No. 200 Sieve (ASTM D1140-17) 4. Density Measurements (ASTM D2937-17e2) 5. Water Soluble Sulfate (California Test 417) 6. Water Soluble Chloride (California Test 422) Moisture content and density measurements were performed by ASTM methods D2216-19 and D2937-17e2, respectively, to establish the in-situ moisture and density of samples retrieved from the exploratory test pits. Laboratory compaction values (ASTM D1557-12r21) establish the optimum moisture content and the laboratory maximum dry density of the tested soils. The relationship between the moisture and density of remolded soil samples helps to establish the relative compaction of the existing fill and soil compaction conditions to be anticipated during any future grading operation. The test results are presented on the logs at the appropriate sample depths. The particle size smaller than a No. 200 sieve analysis (ASTM D1140-17) aids in classifying the tested soils in accordance with the Unified Soil Classification System (attached as Appendix A) and provides qualitative information related to engineering characteristics such as expansion potential, permeability, and shear strength. Water soluble sulfate and chloride tests were performed on samples recovered from the test pits by Clarkson Laboratory and Supply. The test results are attached as Appendix B and indicate an exposure class of S0 for sulfates. LaBounty Residences Job No. 23-14188 Carlsbad, California Page 5 VI. SITE-SPECIFIC SOIL & GEOLOGIC DESCRIPTION Our review of the “Geologic Map of the Oceanside 30’x60’ Quadrangle, California” by Kennedy and Tan, 2007, indicates that the site is mapped as Old Paralic Deposits (Qop6-7). An excerpt of the geologic map is included as Figure No. IV, Geologic Map and Legend. The formational materials are overlain with approximately 3 feet of artificial fill. For more information, see Figure No. II, the Plot Plan with Site-Specific Geology and Figure Nos. IIIa-d, the exploratory test pit logs. A. Stratigraphy Artificial Fill Soils (Qaf): Fill soils consisting of fine to medium grained, loose to medium dense, damp, dark brown silty sand (SM per USCS) were encountered in exploratory test pits HP1 through HP3 to a depth of 3 feet, and to a depth of 2 feet in exploratory test pit HP4. In our opinion, the fill soils are not well compacted and are not suitable in their current condition for support of loads from the proposed residences and associated improvements. The fill soils are considered to have a low expansion potential and are suitable for use as new fill material on the site provided any encountered organics, trash and oversize materials are removed during grading operations and the soils are adequately moisture conditioned. Refer to Figure Nos. IIIa-d for details. Old Paralic Deposits (Qop6-7): Old Paralic Deposit Formational materials were encountered below the fill soils in all the exploratory test pits to the depths explored of 5 to 7 feet. The observed formational materials consisted of 1 foot of loose to medium dense, fine to medium grained, damp, red-brown silty sands (SM per USCS), which were underlain by medium dense, fine to medium grained, damp, light gray- brown silty to poorly graded sand (SM-SP per USCS). In our opinion, the formational LaBounty Residences Job No. 23-14188 Carlsbad, California Page 6 materials are suitable in their current condition for support of loads from the proposed structures and associated improvements. Refer to Figure Nos. IIIa-d for details. B. Structure No geologic structure was observed during our field investigation. VII. GEOLOGIC HAZARDS No significant geologic hazards are known to exist on the subject site that would prohibit the proposed construction. The site, like most of southern California, is located in a seismically active area and regional faulting is present in San Diego County. The following local and regional fault zones are mapped in southern California in general proximity to the site:  Newport-Inglewood Fault: Mapped approximately 5 miles northwest of the site, estimated to be capable of producing a M6.0 to M7.4 earthquake (Grant Ludwig and Shearer, 2004).  Rose Canyon Fault Zone: Mapped approximately 5 miles southwest of the site, considered capable of a M6.9 earthquake (Singleton, et al., 2019).  Coronado Bank Fault: Mapped approximately 21 miles southwest of the site, estimated to be to be capable of a M7.6 earthquake.  Elsinore Fault: Mapped approximately 25 miles northeast of the site, estimated to be capable of a M6.0 to M7.0 earthquake (Rockwell, et al. 1985) and M7.5 (Greensfelder, 1974).  San Jacinto Fault: Mapped approximately 47 miles northeast of the site, estimated to have a 31 percent probability of a M6.7 or greater earthquake within the next 30 years (Working Group on California Earthquake Probabilities, 2008). LaBounty Residences Job No. 23-14188 Carlsbad, California Page 7 Reference to the Geologic Map and Legend, Figure No. IV (Kennedy and Tan, 2007) indicates that no faults are shown to cross the site. Furthermore, the California Geological Survey has not produced an “Earthquake Zones of Required Investigation” regulatory map for this area, indicating that there is no known active faulting in this area. In our explicit opinion, neither an active fault nor a potentially active fault underlies the site. Ground shaking from earthquakes on active southern California faults and active faults in northwestern Mexico is considered the greatest geologic hazard at the site. Further geologic hazards considered in our analysis were ground rupture, landslides, soil liquefaction, tsunamis, seiches, storm surges and flooding. Based on the results of our study, the potential for these hazards to occur are very low and the site is considered low risk. The potential for strong ground shaking from earthquakes on active southern California faults and active faults in northwestern Mexico should be anticipated at the site. Design of building structures in accordance with the current building codes would reduce the potential for injury or loss of human life. Buildings constructed in accordance with current building codes may suffer significant damage but should not undergo total collapse. VIII. GROUNDWATER Groundwater was not encountered during the field investigation and we do not anticipate significant groundwater problems to develop in the future if the property is developed as proposed and proper drainage is implemented and maintained. It should be kept in mind that grading operations can change surface drainage patterns and/or reduce permeabilities due to the densification of compacted soils. Such changes of surface and subsurface hydrologic conditions, plus irrigation of landscaping or significant increases in rainfall, may result in the appearance of LaBounty Residences Job No. 23-14188 Carlsbad, California Page 8 surface or near-surface water at locations where none existed previously. The appearance of such water is expected to be localized and cosmetic in nature, if good positive drainage is implemented, as recommended in this report, during and at the completion of construction. It must be understood that unless discovered during initial site exploration or encountered during site grading operations, it is extremely difficult to predict if or where perched or true groundwater conditions may appear in the future. When site formational soils are fine-grained and of low permeability, water problems may not become apparent for extended periods of time. Water conditions, where suspected or encountered during grading operations, should be evaluated and remedied by the project civil and geotechnical consultants. The project developer and property owner, however, must realize that post-construction appearances of groundwater may have to be dealt with on a site-specific basis. IX. CONCLUSIONS AND RECOMMENDATIONS From a geotechnical engineering standpoint, it is our opinion that the lots are suitable for the proposed residences and associated improvements provided the conclusions and recommendations presented in this report are incorporated into their design and construction. The primary feature of concern at the site is the presence of poorly compacted existing fill soils. In order to preclude the possibility of the new residences and associated improvements being subject to excessive total and differential settlements, we recommend that all existing fill soils be removed and recompacted. LaBounty Residences Job No. 23-14188 Carlsbad, California Page 9 Earthwork and foundation recommendations are presented in the following paragraphs. It should be noted that the recommendations for allowable footing bearing pressures, passive soil resistance and coefficient of friction presented below are based on presumptive values for Class 4 soils in the 2022 CBC. The opinions, conclusions, and recommendations presented in this report are contingent upon Geotechnical Exploration, Inc. being retained to review the final plans and specifications as they are developed and to observe the site earthwork and installation of foundations. Accordingly, we recommend that the following paragraph be included on the grading and foundation plans for the projects: If the geotechnical consultant of record is changed for the project, the work shall be stopped until the replacement has agreed in writing to accept the responsibility within their area of technical competence for approval upon completion of the work. It shall be the responsibility of the permittee to notify the governing agency in writing of such change prior to the commencement or recommencement of grading and/or foundation installation work A. Site Preparation and Earthwork 1. Clearing and Stripping: The subject lots should be cleared of all obstructions, including the existing structures and associated improvements to be demolished, any utility lines to be abandoned and any miscellaneous debris that may be present at the time of construction. After clearing, the ground surface should be stripped of surface vegetation as well as associated root systems. Holes resulting from the removal of buried obstructions that extend below the proposed finished site grades should be cleared and backfilled with suitable material compacted to the requirements given under Recommendation No. 4, "Compaction.” The cleared and stripped materials should be properly disposed of off-site. LaBounty Residences Job No. 23-14188 Carlsbad, California Page 10 2. Treatment of Existing Fill: In order to provide suitable foundation support for the proposed new residences and associated improvements, we recommend that all existing fill soils on the lots that remain after the necessary site excavations have been made be removed and recompacted. The areal extent and depth required to remove the existing fill soils should be determined by our representatives during the excavation work based on their examination of the soils being exposed. The anticipated depth of removal is on the order of 3 feet below existing grade. Any unsuitable materials (such as oversize rubble and/or organic matter) should be selectively removed as directed by our representative and disposed of off-site. After removal of existing fill, the exposed natural subgrade materials should be scarified to a depth of 6 inches, moisture conditioned to at least 2 percent above the laboratory optimum and compacted to a minimum degree of compaction of 90 percent. 3. Materials for Fill: All on-site soils with an organic content of less than 3 percent by volume are suitable for reuse as fill material. Fill material should not, however, contain rocks or lumps over 3 inches in greatest dimension and not more than 15 percent larger than ¼-inch. In addition to the preceding size requirements, any required imported fill soil should be a granular soil with an Expansion Index of 50 or less per ASTM D4829-19 and be approved by our representative prior to importation to the site. 4. Compaction: All structural fill and backfill should be compacted to a minimum degree of compaction of 90 percent at a moisture content at least 2 percent above the optimum moisture content based upon ASTM D1557-12r21. All fill material should be spread and compacted in uniform horizontal lifts not exceeding 8 inches in uncompacted thickness. Before compaction begins, the fill should be brought to a moisture content that will permit proper compaction by either: (1) aerating and drying the fill if it is too wet; or (2) watering the fill LaBounty Residences Job No. 23-14188 Carlsbad, California Page 11 if it is too dry. Each lift should be thoroughly mixed before compaction to ensure a uniform distribution of moisture. 5. Trench Backfill: All pipeline trenches should be backfilled with compacted fill. Backfill material should be placed in lift thicknesses appropriate to the type of compaction equipment utilized and compacted to a minimum degree of compaction of 90 percent by mechanical means. Our experience has shown that even shallow, narrow trenches, such as for irrigation and electrical lines, which are not properly compacted, can result in problems, particularly with respect to shallow groundwater accumulation and migration. 6. Drainage: Positive surface gradients should be provided adjacent to the structures, and roof gutters and downspouts should be installed to direct water away from foundations and slabs toward suitable discharge facilities. Ponding of surface water should not be allowed, especially adjacent to the structures, driveways and flatwork. 7. Observations and Testing: As stated in CBC 2022, Section 1705.6 Soils: “Special inspections and tests of existing site soil conditions, fill placement and load-bearing requirements shall be performed in accordance with this section and Table 1705.6 (see below). The approved geotechnical report and the construction documents prepared by the registered design professionals shall be used to determine compliance. During fill placement, the special inspector shall verify that proper materials and procedures are used in accordance with the provisions of the approved geotechnical report.” A summary of Table 1705.6 “REQUIRED SPECIAL INSPECTIONS AND TESTS OF SOILS” is presented below: LaBounty Residences Job No. 23-14188 Carlsbad, California Page 12 a) Verify materials below shallow foundations are adequate to achieve the design bearing capacity; b) Verify excavations are extended to proper depth and have reached proper material; c) Perform classification and testing of compacted fill materials; d) Verify use of proper materials, densities and fill thicknesses during placement and compaction of compacted fill prior to placement of compacted fill, inspect subgrade and verify that site has been prepared properly. Section 1705.6 “Soils” statement and Table 1705.6 indicates that it is mandatory that a representative of this firm (responsible engineering firm) perform observations and fill compaction testing during grading and backfilling operations to verify that the operations are consistent with the recommendations presented in this report. All grading excavations resulting from the removal of soils should be observed and evaluated by a representative of our firm before they are backfilled. Quality control grading observation and field density testing for the purpose of documenting that adequate compaction has been achieved and acceptable soils have been utilized to properly support a project applies not only to fill soils supporting primary structures (unless supported by deep foundations or caissons) but all site improvements such as stairways, patios, pools and pool decking, retaining walls, etc. Observation and testing of utility line trench backfill also reduces the potential for localized settlement of all of the above including all improvements outside of the footprint of primary structures. LaBounty Residences Job No. 23-14188 Carlsbad, California Page 13 Often after primary building pad grading and swimming pool excavation, it is not uncommon for the geotechnical engineer of record to not be notified of grading performed outside the footprint of the project primary structures. As a result, settlement damage of site improvements such as patios, pool and pool decks, exterior landscape walls and walks, and structure access stairways can occur. It is therefore strongly recommended that the project general contractor, grading contractor, and others tasked with completing the project, be advised and acknowledge the importance of adequate and comprehensive observation and testing of soils intended to support the project they are working on. The project geotechnical engineer of record must be contacted and requested to provide these services. The geotechnical engineer of record, in this case Geotechnical Exploration, Inc., cannot be held responsible for the costs and time delays associated with the lack of contact and requests for testing services by the client, general contractor, grading contractor or any of the project design team responsible for requesting the required geotechnical services. Requests for services are to be made through our office telephone number (858) 549-7222 and the telephone number of the GEI personnel assigned to the project. B. Foundation Recommendations 8. Footings: We recommend that the proposed residences be supported on conventional, individual-spread and/or continuous footing foundations bearing on undisturbed formational materials and/or properly compacted structural fill soils prepared as recommended above in Recommendations Nos. 2, 3 and 4. All footings should be founded at least 18 inches below the lowest adjacent finished grade. LaBounty Residences Job No. 23-14188 Carlsbad, California Page 14 At the recommended depths, footings may be designed for allowable bearing pressures of 2,000 pounds per square foot (psf) for combined dead and live loads and 2,600 psf for all loads, including wind or seismic. The footings should, however, have a minimum width of 12 inches. 9. General Criteria for All Footings: Footings located adjacent to the tops of slopes should be extended sufficiently deep so as to provide at least 10 feet of horizontal cover between the slope face and outside edge of the footing at the footing bearing level. Footings located adjacent to utility trenches should have their bearing surfaces situated below an imaginary 1.5 to 1.0 plane projected upward from the bottom edge of the adjacent utility trench. All continuous footings should contain top and bottom reinforcement to provide structural continuity and to permit spanning of local irregularities. We recommend that a minimum of two No. 5 top and two No. 5 bottom reinforcing bars be provided in the footings. A minimum clearance of 3 inches should be maintained between steel reinforcement and the bottom or sides of the footing. In order for us to offer an opinion as to whether the footings are founded on soils of sufficient load bearing capacity, it is essential that our representative inspect the footing excavations prior to the placement of reinforcing steel or concrete. NOTE: The project Civil/Structural Engineer should review all reinforcing schedules. The reinforcing minimums recommended herein are not to be construed as structural designs, but merely as minimum reinforcement to reduce the potential for cracking and separations LaBounty Residences Job No. 23-14188 Carlsbad, California Page 15 10. Seismic Design Criteria: Site-specific seismic design criteria for the proposed residences are presented in the following table in accordance with Section 1613 of the 2022 CBC, which incorporates by reference ASCE 7-16 for seismic design. We have determined the mapped spectral acceleration values for the site, based on a latitude of 33.14786 degrees and longitude of -117.34325 degrees, utilizing a tool provided by the USGS, which provides a solution for ASCE 7-16 (Section 1613 of the 2022 CBC) utilizing digitized files for the Spectral Acceleration maps. Based on our past experience with similar conditions, we have assigned a Site Soil Classification of C. TABLE I Mapped Spectral Acceleration Values and Design Parameters Ss S1 Fa Fv Sms Sm1 Sds Sd1 1.097g 0.396g 1.2 1.5 1.317g 0.593g 0.878g 0.396g 11. Lateral Loads: Lateral load resistance for the structures supported on footing foundations may be developed in friction between the foundation bottoms and the supporting subgrade. An allowable friction coefficient of 0.25 is considered applicable. An additional allowable passive resistance equal to an equivalent fluid weight of 150 pcf acting against the foundations may be used in design provided the footings are poured neat against the adjacent properly compacted fill materials and/or undisturbed formational materials. These lateral resistance values assume a level surface in front of the footing for a minimum distance of three times the embedment depth of the footing and any shear keys. 12. Settlement: Settlement under building loads is expected to be within tolerable limits for the proposed structures. For footings designed in accordance with the recommendations presented in the preceding paragraphs, we anticipate LaBounty Residences Job No. 23-14188 Carlsbad, California Page 16 that total settlements should not exceed 1 inch and that post-construction differential settlements should be less than 1/240. C. Concrete Slab On-grade Criteria 13. Minimum Floor Slab and Garage Slab Thickness and Reinforcement: Based on our experience, we have found that, for various reasons, floor slabs occasionally crack, causing brittle surfaces such as ceramic tiles to become damaged. Therefore, we recommend that all slabs on-grade contain at least a minimum amount of reinforcing steel to reduce the separation of cracks, should they occur. Actual floor slab thickness and reinforcement recommendations should be provided by the project Structural Engineer. 13.1 Interior floor slabs (and garage slabs and driveways subject only to automobile traffic) should be a minimum of 5 inches in thickness and be reinforced with No. 4 bars on 18-inch centers, both ways, placed at mid- height in the slab. Concrete for any garage slabs and driveways should conform to Section 201 of The Standard Specifications for Public Works Construction, 2024 Edition, for Class 560-C-3250. Slab subgrade soil should be verified by a Geotechnical Exploration, Inc. representative to have the proper moisture content within 48 hours prior to placement of the vapor barrier and pouring of concrete. 13.2 Following placement of any concrete floor slabs, sufficient drying time must be allowed prior to placement of floor coverings. Premature placement of floor coverings may result in degradation of adhesive materials and loosening of the finish floor materials. LaBounty Residences Job No. 23-14188 Carlsbad, California Page 17 We note that shrinkage cracking can result in reflective cracking in brittle flooring surfaces such as stone and tiles. It is imperative that if movement intolerant flooring materials are to be utilized, the flooring contractor and/or architect should provide specifications for the use of high-quality isolation membrane products installed between slab and floor materials. 14. Slab Moisture Protection and Vapor Barrier Membrane: Although it is not the responsibility of geotechnical engineering firms to provide moisture protection recommendations, as a service to our clients we provide the following discussion and suggested minimum protection criteria. Actual recommenda- tions should be provided by the architect and waterproofing consultants. Soil moisture vapor can result in damage to moisture-sensitive floors, some floor sealers, or sensitive equipment in direct contact with the floor, in addition to mold and staining on slabs, walls and carpets. The common practice in Southern California is to place vapor retarders made of PVC, or of polyethylene. PVC retarders are made in thickness ranging from 10- to 60-mil. Polyethylene retarders, called visqueen, range from 5- to 10-mil in thickness. These products are no longer considered adequate for moisture protection and can actually deteriorate over time. Specialty vapor retarding products possess higher tensile strength and are more specifically designed for and intended to retard moisture transmission into and through concrete slabs. The use of such products is highly recommended for reduction of floor slab moisture emission. The following American Society for Testing and Materials (ASTM) and American Concrete Institute (ACI) sections address the issue of moisture transmission into and through concrete slabs: ASTM E154/E154M-08a(2019) Standard Test LaBounty Residences Job No. 23-14188 Carlsbad, California Page 18 Methods for Water Vapor Retarders Used in Contact with Earth Under Concrete Slabs, on Walls, or as Ground Cover; ASTM E96-00e1 Standard Test Methods for Water Vapor Transmission of Materials; ASTM E1643-18a Standard Practice for Selection, Design, Installation and Inspection of Water Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs; and ACI 302.2R-06 Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials. 14.1 Based on the above, we recommend that the vapor barrier consist of a minimum 15-mil extruded polyolefin plastic (no recycled content or woven materials permitted). Permeance as tested before and after mandatory conditioning (ASTM E1745 Section 7.1 and sub-paragraphs 7.1.1-7.1.5) should be less than 0.01 US perms (grains/square foot/hour/inch of mercury Hg) and comply with the ASTM E1745 Class A requirements. Installation of vapor barriers should be in accordance with ASTM E1643. The basis of design is StegoWrap vapor barrier 15- mil. Reef Industries Vapor Guard membrane has also been shown to achieve a permeance of less than 0.01 perm. We recommend that the recommended vapor barrier be placed directly on properly prepared subgrade soils and the floor slabs be poured directly on the vapor barrier; no sand or gravel layers are used. 14.2 Common to all acceptable products, vapor retarder/barrier joints must be lapped at least 6 inches. Seam joints and permanent utility penetrations should be sealed with the manufacturer’s recommended tape or mastic. Edges of the vapor retarder should be extended to terminate at a location in accordance with ASTM E1643-18a or to an alternate location that is acceptable to the project’s structural engineer. All terminated edges of the vapor retarder should be sealed to the LaBounty Residences Job No. 23-14188 Carlsbad, California Page 19 building foundation (grade beam, wall, or slab) using the manufacturer’s recommended accessory for sealing the vapor retarder to pre-existing or freshly placed concrete. In actual practice, stakes are often driven through the retarder material, equipment is dragged or rolled across the retarder, overlapping or jointing is not properly implemented, etc. All these construction deficiencies reduce the retarder’s effectiveness. In no case should retarder/barrier products be punctured or gaps be allowed to form prior to or during concrete placement. Vapor barrier- safe screeding and forming systems should be used that will not leave puncture holes in the vapor barrier, such as Beast Foot (by Stego Industries) or equivalent. 14.3 Vapor retarders/barriers do not provide full waterproofing for structures constructed below free water surfaces. They are intended to help reduce or prevent vapor transmission and/or capillary migration through the soil and through the concrete slabs. Waterproofing systems must be designed and properly constructed if full waterproofing is desired. The owner and project designers should be consulted to determine the specific level of protection required. 14.4 Following placement of concrete floor slabs, sufficient drying time must be allowed prior to placement of any floor coverings. Premature placement of floor coverings may result in degradation of adhesive materials and loosening of the finish floor materials. 15. Exterior Slab Thickness and Reinforcement: Exterior slab reinforcement and control joints should be designed by the project Structural Engineer. As a minimum for protection of on-site improvements, we recommend that all exterior pedestrian concrete slabs be at least 4 inches thick and founded on LaBounty Residences Job No. 23-14188 Carlsbad, California Page 20 properly compacted and tested fill, with No. 3 bars at 18-inch centers, both ways, at the center of the slab, and contain adequate isolation and control joints. The performance of on-site improvements can be greatly affected by soil base preparation and the quality of construction. It is therefore important that all improvements are properly designed and constructed for the existing soil conditions. The improvements should not be built on loose soils or fills placed without our observation and testing. For exterior slabs with the minimum shrinkage reinforcement, control joints should be placed at spaces no farther than 15 feet apart or the width of the slab, whichever is less, and also at re-entrant corners. Control joints in exterior slabs should be sealed with elastomeric joint sealant. The sealant should be inspected every 6 months and be properly maintained. D. General Recommendations 16. Infiltration Feasibility: The subject lots are underlain by 3 to 4 feet of fill soils over dense formational sandstone. We anticipate that the adjacent existing residential lots as well as Garfield Street are underlain by similar materials. In our opinion, the formational sandstone materials would have poor infiltration characteristics and any attempted infiltration would quite likely lead to a spreading perched groundwater condition and hydroconsolidation of fill soils under the proposed construction and adjacent residences. In addition, the perched groundwater condition would lead to flooding of utility trenches. Accordingly, it is our opinion that the lots are not suitable for infiltration and we recommend that all biofiltration basins be lined with an impermeable liner. LaBounty Residences Job No. 23-14188 Carlsbad, California Page 21 17. Project Start Up Notification: In order to minimize any work delays during site development, this firm should be contacted 24 hours prior to any need for observation of footing excavations or field density testing of compacted fill soils. If possible, placement of formwork and steel reinforcement in footing excavations should not occur prior to observing the excavations; in the event that our observations reveal the need for deepening or re-designing foundation structures at any locations, any formwork or steel reinforcement in the affected footing excavation areas would have to be removed prior to correction of the observed problem (i.e., deepening the footing excavation, recompacting soil in the bottom of the excavation, etc.). 18. Construction Best Management Practices (BMPs): Sufficient BMPs must be installed to prevent silt, mud, or other construction debris from being tracked into the adjacent street(s) or stormwater conveyance systems due to construction vehicles or any other construction activity. The contractor is responsible for cleaning any such debris that may be in the street at the end of each work day or after a storm event that causes a breach in the installed construction BMPs. All stockpiles of uncompacted soil and/or building materials that are left unprotected for a period greater than 7 days are to be provided with erosion and sediment controls. Such soil must be protected each day when the probability of rain is 40% or higher. A concrete washout should be provided on all projects that propose the construction of any concrete improvements that are to be poured in place. All erosion/sediment control devices should be maintained and in working order at all times. All slopes that are created or disturbed by construction activity must be protected against erosion and sediment transport at all times. The storage of all construction materials and LaBounty Residences Job No. 23-14188 Carlsbad, California Page 22 equipment must be protected against any potential release of pollutants into the environment. X. GRADING NOTES Geotechnical Exploration, Inc. recommends that we be retained to verify the actual soil conditions revealed during site grading work and footing excavations to be as anticipated in this "Report of Preliminary Geotechnical Investigation" for the project. In addition, the compaction of any fill soils placed during site grading work must be observed and tested by the soil engineer. It is the responsibility of the grading contractor to comply with the requirements on the grading plans and the local grading ordinance. All trench backfill should be properly compacted. Geotechnical Exploration, Inc. will assume no liability for damage occurring due to improperly or uncompacted backfill placed without our observation and testing. XI. LIMITATIONS Our conclusions and recommendations have been based on available data obtained from our field investigation and laboratory analysis, as well as our experience with similar soils and formational materials located in this area of San Diego County. Of necessity, we must assume a certain degree of continuity between exploratory excavations. It is, therefore, necessary that all observations, conclusions, and recommendations be verified at the time grading operations begin or when footing excavations are placed. In the event discrepancies are noted, additional recommendations may be issued, if required. LaBounty Residences Job No. 23-14188 Carlsbad, California Page 23 The firm of Geotechnical Exploration, Inc. shall not be held responsible for changes to the physical condition of the property, such as addition of fill soils or changing drainage patterns, which occur subsequent to issuance of this report and the changes are made without our observations, testing, and approval. The work performed and recommendations presented herein are the result of an investigation and analysis that meet the contemporary standard of care in our profession within the County of San Diego. No warranty is provided. This report should be considered valid for a period of two (2) years, and is subject to review by our firm following that time. If significant modifications are made to the building plans, especially with respect to the height and location of any proposed structures, this report must be presented to us for immediate review and possible revision. It must be understood that it is not within the scope of our services to provide quality control oversight for surface or subsurface drainage construction or retaining wall sealing and base of wall drain construction. It is the responsibility of the contractor to verify and provide proper surface drainage at the site, wall sealing, geofabric installation, protection board (if needed), drain depth below interior floor or yard surface, pipe percent slope to the outlet, etc. This firm does not practice or consult in the field of safety engineering. We do not direct the contractor's operations, and we cannot be responsible for the safety of personnel other than our own on the site; the safety of others is the responsibility of the contractor. The contractor should notify the owner if any of the recommended actions presented herein are considered to be unsafe. LaBounty Residences Job No. 23-14188 Carlsbad, California Page 24 It is the responsibility of the owner and/or developer to ensure that the recommendations summarized in this report are carried out in the field operations and that our recommendations for design of this project are incorporated in the structural plans. We should be retained to review the project plans once they are available, to verify that our recommendations are adequately incorporated in them. Once again, should any questions arise concerning this report, please feel free to contact the undersigned. Reference to our Job No. 23-14188 will expedite a reply to your inquiries. Respectfully submitted, GEOTECHNICAL EXPLORATION, INC. _______________________________ ______________________________ Wm. D. Hespeler, G.E. 396 Jay K. Heiser Senior Geotechnical Engineer Senior Project Geologist REFERENCES JOB NO. 23-14188 June 2024 2007 Working Group on California Earthquake Probabilities, 2008, The Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2), U.S Geological Survey Open-file Report 2007-1437 and California Geological Survey Special Report 203. Berger, V. and Schug, D.L., 1991, Probabilistic Evaluation of Seismic Hazard in the San Diego-Tijuana Metropolitan Region, Environmental Perils, San Diego Region, Geological Society of America by the San Diego Association of Geologists, October 20, 1991, p. 89-99. Demere, T.A. 1997, Geology of San Diego County, California, San Diego Natural History Museum, http://archive.sdnhm.org/research/paleontology/sdgeol.html, accessed July 30, 2020. Grant Ludwig, L.B. and Shearer, P.M., 2004, Activity of the Offshore Newport-Inglewood Rose Canyon Fault Zone, Coastal Southern California, from Relocated Microseismicity, Bulletin of the Seismological Society of America, 94(2), 747-752. Greene, H.G., Bailey, K.A., Clarke, S.H., Ziony, J.I. and Kennedy, M.P., 1979, Implications of fault patterns of the inner California continental borderland between San Pedro and San Diego, in Abbott, P.L., and Elliot, W.J., eds., Earthquakes and other perils, San Diego region: San Diego Association of Geologists, Geological Society of America field trip, November, 1979, p. 21–28. Hart, E.W. and Bryant, W.A., 1997, Fault-Rupture Hazard Zones in California, California Division of Mines and Geology, Special Publication 42. Hart, E.W., Smith, D.P. and Saul, R.B., 1979, Summary Report: Fault Evaluation Program, 1978 Area (Peninsular Ranges-Salton Trough Region), California Division of Mines and Geology, Open-file Report 79-10 SF, 10. Jennings, C.W., and Bryant, W.A., 2010, Fault Activity Map of California, California Geological Survey Geologic Data Map No. 6 Kennedy, M.P. and Tan, S.S., 2007, Geologic Map 30’x60’ Oceanside Quadrangle, California, California Geological Survey, Department of Conservation. Legg, M., and Agnew, D., 1979, The 1862 Earthquake in San Diego, in Earthquakes and Other Perils: San Diego Region (Abbott, P.L., Elliott, W.J., eds.), San Diego Association of Geologists, San Diego, CA 139-141. Rockwell, T.K., 2010, The Rose Canyon Fault Zone in San Diego, Proceedings of the Fifth International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics. Paper No. 7.06C. Rockwell, T.K., Dawson, T.E., Young Ben-Horin, J. and Seitz, G., 2014, A 21-Event, 4,000-Year History of Surface Ruptures in the Anza Seismic Gap, San Jacinto Fault, and Implications for Long-term Earthquake Production on a Major Plate Boundary Fault, Pure and Applied Geophysics, v. 172, 1143– 1165 (2015). Rockwell, T.K., Millman, D.E., McElwain, R.S. and Lamar, D.L., 1985, Study of Seismic Activity by Trenching Along the Glen Ivy North Fault, Elsinore Fault Zone, Southern California: Lamar-Merifield Technical Report 85-1, U.S.G.S. Contract 14-08-0001-21376, 19 p. REFERENCES/Page 2 Ross, Z.E., Hauksson E. and Ben-Zion Y., 2017, Abundant Off-fault Seismicity and Orthogonal Structures in the San Jacinto Fault Zone, Science Advances, 2017; 3(3): e1601946. Singleton, D.M., Rockwell, T.K., Murbach, D., Murbach, M., Maloney, J., Freeman, T., Levy, Y., 2019, Late-Holocene Rupture History of the Rose Canyon Fault in Old Town, San Diego: Implications of Cascading Earthquakes on the Newport-Inglewood-Rose Canyon Fault System, Bulletin of the Seismological Society of America 109, p. 855-874. Southern California Earthquake Data Center (SCEDC), 2022, Earthquake Information, Fault Name Index, Division of Geological and Planetary Sciences, California Institute of Technology. Toppozada, T.R. and Parke, D.L., 1982, Areas Damaged by California Earthquakes, 1900-1949, California Division of Mines and Geology, Open-file Report. 82-17. VICINITY MAP LaBounty Residences 3940 and 3950 Garfield Carlsbad, CA. Figure No. I Job No. 23-14188 SITESITE Thomas Bros Guide San Diego County pg 1106-D5 Ex i s t i n g S t r u c t u r e HP - 4 Ap p r o x i m a t e L o c a t i o n of E x p l o r a t o r y H a n d p i t HP - 1 HP - 3 HP - 2 HP - 4 Qa f Qo p 6- 7 Qa f Qo p 6- 7 Ar t i f i c i a l F i l l G E O L O G I C U N I T S Ol d P a r a l i c D e p o s i t s , U n i t s 6 & 7 Qa f Qo p 6- 7 Qa f Qo p 6- 7 Qa f Qo p 6- 7 PL O T P L A N A N D SI T E S P E C I F I C GE O L O G I C M A P La B o u n t y R e s i d e n c e s 39 4 0 & 3 9 5 0 G a r f i e l d S t r e e t Ca r l s b a d , C A . Fi g u r e N o . I I Jo b N o . 2 3 - 1 4 1 8 8 L E G E N D 23 - 1 4 1 8 8 - P . a i RE F E R E N C E : T h i s P l o t P l a n w a s p r e p a r e d f r o m a n e x i s t i n g TO P O G R A P H I C S U R V E Y b y C O F F E Y E N G I N E E R I N G , I N C . da t e d 9 / 1 4 / 2 1 a n d f r o m o n - s i t e f i e l d r e c o n n a i s s a n c e pe r f o r m e d b y G E I . NO T E : T h i s P l o t P l a n i s n o t t o b e u s e d f o r l e g a l pu r p o s e s . L o c a t i o n s a n d d i m e n s i o n s a r e a p p r o x i m a t e . Ac t u a l p r o p e r t y d i m e n s i o n s a n d l o c a t i o n s o f u t i l i t i e s ma y b e o b t a i n e d f r o m t h e A p p r o v e d B u i l d i n g P l a n s or t h e “ A s - B u i l t ” G r a d i n g P l a n s . Ju ly 20 2 4 GARFIELD STREET N GR A P H I C S C A L E 1” = 2 0 ’ ( a p p r o x i m a t e ) 10 0 10 20 40 30 SE Q U O I A AV E N U E SILTY SAND , fine- to medium-grained, withsome roots. Loose to medium dense. Damp. Dark brown. FILL (Qaf) SILTY SAND , fine- to medium-grained. Loose to medium dense. Damp. Red-brown. OLD PARALIC DEPOSITS (Qop 6-7) SILTY-POORLY GRADED SAND , fine- tomedium-grained; poorly cemented. Medium dense. Damp. Light gray-brown. OLD PARALIC DEPOSITS (Qop 6-7) Bottom @ 5' SM SM SM-SP DE P T H ( f e e t ) FIGURE NUMBER 23-14188 GROUNDWATER/ SEEPAGE DEPTH FIELD DESCRIPTION AND CLASSIFICATION 3-13-23 1 2 3 4 5 6 JOB NUMBER SA M P L E HP-1 DATE LOGGED Not Encountered DIMENSION & TYPE OF EXCAVATION SA M P L E O . D . (I N C H E S ) La Bounty Residences SY M B O L BL O W CO U N T S / F T . REVIEWED BY JKH± 70' Mean Sea Level IIIa 1 SITE LOCATION JOB NAME 3940 and 3950 Garfield Street, Carlsbad, CA PERCHED WATER TABLE BULK BAG SAMPLE IN-PLACE SAMPLE MODIFIED CALIFORNIA SAMPLE NUCLEAR FIELD DENSITY TEST STANDARD PENETRATION TEST WDH LOGGED BYSURFACE ELEVATION 3' X 3' X 5' Test Pit DESCRIPTION AND REMARKS (Grain size, Density, Moisture, Color) Hand Tools EQUIPMENT LOG No. EX P L O R A T I O N L O G 1 4 1 8 8 L A B O U N T Y . G P J G E O _ E X P L . G D T 4 / 1 0 / 2 3 (% ) IN - P L A C E MO I S T U R E ( % ) MA X I M U M D R Y DE N S I T Y ( p c f ) EX P A N . + CO N S O L . - DE N S I T Y (% o f M . D . D . ) OP T I M U M MO I S T U R E ( % ) IN - P L A C E D R Y DE N S I T Y ( p c f ) U. S . C . S . SILTY SAND , fine- to medium-grained, withsome roots. Loose to medium dense. Damp. Dark brown. FILL (Qaf) SILTY SAND , fine- to medium-grained. Loose to medium dense. Damp. Red-brown. OLD PARALIC DEPOSITS (Qop 6-7)-- 15% passing #200 sieve. SILTY-POORLY GRADED SAND , fine- tomedium-grained; poorly cemented. Medium dense. Damp. Light gray-brown. OLD PARALIC DEPOSITS (Qop 6-7) Bottom @ 7' 103.2 120.97.5 SM SM SM- SP 7.7 DE P T H ( f e e t ) FIGURE NUMBER 23-14188 GROUNDWATER/ SEEPAGE DEPTH FIELD DESCRIPTION AND CLASSIFICATION 3-13-23 1 2 3 4 5 6 7 8 JOB NUMBER SA M P L E HP-2 DATE LOGGED Not Encountered DIMENSION & TYPE OF EXCAVATION SA M P L E O . D . (I N C H E S ) La Bounty Residences SY M B O L BL O W CO U N T S / F T . REVIEWED BY JKH± 65' Mean Sea Level IIIb 1 SITE LOCATION JOB NAME 3940 and 3950 Garfield Street, Carlsbad, CA PERCHED WATER TABLE BULK BAG SAMPLE IN-PLACE SAMPLE MODIFIED CALIFORNIA SAMPLE NUCLEAR FIELD DENSITY TEST STANDARD PENETRATION TEST WDH LOGGED BYSURFACE ELEVATION 3' X 3' X 7' Test Pit DESCRIPTION AND REMARKS (Grain size, Density, Moisture, Color) Hand Tools EQUIPMENT LOG No. EX P L O R A T I O N L O G 1 4 1 8 8 L A B O U N T Y . G P J G E O _ E X P L . G D T 4 / 1 0 / 2 3 (% ) IN - P L A C E MO I S T U R E ( % ) MA X I M U M D R Y DE N S I T Y ( p c f ) EX P A N . + CO N S O L . - DE N S I T Y (% o f M . D . D . ) OP T I M U M MO I S T U R E ( % ) IN - P L A C E D R Y DE N S I T Y ( p c f ) U. S . C . S . SILTY SAND , fine- to medium-grained, withsome roots. Loose to medium dense. Damp. Dark brown. FILL (Qaf) Hand auger from 3'- 7'. SILTY SAND , fine- to medium-grained. Looseto medium dense. Damp. Red-brown. OLD PARALIC DEPOSITS (Qop 6-7) SILTY-POORLY GRADED SAND , fine- to medium-grained; poorly cemented. Medium dense. Damp. Light gray-brown. OLD PARALIC DEPOSITS (Qop 6-7) Bottom @ 7' SM SM SM- SP DE P T H ( f e e t ) FIGURE NUMBER 23-14188 GROUNDWATER/ SEEPAGE DEPTH FIELD DESCRIPTION AND CLASSIFICATION 3-13-23 1 2 3 4 5 6 7 8 JOB NUMBER SA M P L E HP-3 DATE LOGGED Not Encountered DIMENSION & TYPE OF EXCAVATION SA M P L E O . D . (I N C H E S ) La Bounty Residences SY M B O L BL O W CO U N T S / F T . REVIEWED BY JKH± 65' Mean Sea Level IIIc 1 SITE LOCATION JOB NAME 3940 and 3950 Garfield Street, Carlsbad, CA PERCHED WATER TABLE BULK BAG SAMPLE IN-PLACE SAMPLE MODIFIED CALIFORNIA SAMPLE NUCLEAR FIELD DENSITY TEST STANDARD PENETRATION TEST WDH LOGGED BYSURFACE ELEVATION 3' X 3' X 7' Test Pit DESCRIPTION AND REMARKS (Grain size, Density, Moisture, Color) Hand Tools, Hand Auger EQUIPMENT LOG No. EX P L O R A T I O N L O G 1 4 1 8 8 L A B O U N T Y . G P J G E O _ E X P L . G D T 4 / 1 0 / 2 3 (% ) IN - P L A C E MO I S T U R E ( % ) MA X I M U M D R Y DE N S I T Y ( p c f ) EX P A N . + CO N S O L . - DE N S I T Y (% o f M . D . D . ) OP T I M U M MO I S T U R E ( % ) IN - P L A C E D R Y DE N S I T Y ( p c f ) U. S . C . S . SILTY SAND , fine- to medium-grained, withsome roots. Loose to medium dense. Damp. Dark brown. FILL (Qaf) SILTY SAND , fine- to medium-grained. Loose to medium dense. Damp. Red-brown. OLD PARALIC DEPOSITS (Qop 6-7) Hand auger from 3'- 7'. SILTY-POORLY GRADED SAND , fine- to medium-grained; poorly cemented. Medium dense. Damp. Light gray-brown. OLD PARALIC DEPOSITS (Qop 6-7) Bottom @ 7' SM SM SM- SP DE P T H ( f e e t ) FIGURE NUMBER 23-14188 GROUNDWATER/ SEEPAGE DEPTH FIELD DESCRIPTION AND CLASSIFICATION 3-13-23 1 2 3 4 5 6 7 8 JOB NUMBER SA M P L E HP-4 DATE LOGGED Not Encountered DIMENSION & TYPE OF EXCAVATION SA M P L E O . D . (I N C H E S ) La Bounty Residences SY M B O L BL O W CO U N T S / F T . REVIEWED BY JKH± 65' Mean Sea Level IIId 1 SITE LOCATION JOB NAME 3940 and 3950 Garfield Street, Carlsbad, CA PERCHED WATER TABLE BULK BAG SAMPLE IN-PLACE SAMPLE MODIFIED CALIFORNIA SAMPLE NUCLEAR FIELD DENSITY TEST STANDARD PENETRATION TEST WDH LOGGED BYSURFACE ELEVATION 3' X 3' X 7' Test Pit DESCRIPTION AND REMARKS (Grain size, Density, Moisture, Color) Hand Tools, Hand Auger EQUIPMENT LOG No. EX P L O R A T I O N L O G 1 4 1 8 8 L A B O U N T Y . G P J G E O _ E X P L . G D T 4 / 1 0 / 2 3 (% ) IN - P L A C E MO I S T U R E ( % ) MA X I M U M D R Y DE N S I T Y ( p c f ) EX P A N . + CO N S O L . - DE N S I T Y (% o f M . D . D . ) OP T I M U M MO I S T U R E ( % ) IN - P L A C E D R Y DE N S I T Y ( p c f ) U. S . C . S . La B o u n t y R e s i d e n c e s 39 4 0 & 3 9 5 0 G a r f i e l d S t r e e t Ca r l s b a d , C A . SI T E Fi g u r e N o . I V Jo b N o . 2 3 - 1 4 1 8 8 Ap r i l 2 0 2 3 LA B O U N T Y - O C - g e o . a i PA C I F I C OC E A N EX C E R P T F R O M Qo p Qu a r t e n a r y O l d P a r a l i c D e p o s i t s ( u n i t 6 - 7 ) 6- 7 APPENDIX A UNIFIED SOIL CLASSIFICATION SYSTEM (U.S.C.S.) SOIL DESCRIPTION Coarse-grained (More than half of material is larger than a No. 200 sieve) GRAVELS, CLEAN GRAVELS GW Well-graded gravels, gravel and sand mixtures, little (More than half of coarse fraction or no fines. is larger than No. 4 sieve size, but smaller than 3”) GP Poorly graded gravels, gravel and sand mixtures, little or no fines. GRAVELS WITH FINES GC Clay gravels, poorly graded gravel-sand-silt mixtures SANDS, CLEAN SANDS SW Well-graded sand, gravelly sands, little or no fines (More than half of coarse fraction is smaller than a No. 4 sieve) SP Poorly graded sands, gravelly sands, little or no fines. SANDS WITH FINES SM Silty sands, poorly graded sand and silty mixtures. SC Clayey sands, poorly graded sand and clay mixtures. Fine-grained (More than half of material is smaller than a No. 200 sieve) SILTS AND CLAYS Liquid Limit Less than 50 ML Inorganic silts and very fine sands, rock flour, sandy silt and clayey-silt sand mixtures with a slight plasticity CL Inorganic clays of low to medium plasticity, gravelly clays, silty clays, lean clays. OL Organic silts and organic silty clays of low plasticity. Liquid Limit Greater than 50 MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts. CH Inorganic clays of high plasticity, fat clays. OH Organic clays of medium to high plasticity. HIGHLY ORGANIC SOILS PT Peat and other highly organic soils APPENDIX B Soluble Sulfate and Chloride Test Results L A B O R A T O R Y R E P O R T Telephone (619) 425-1993 Fax 425-7917 Established 1928 C L A R K S O N L A B O R A T O R Y A N D S U P P L Y I N C. 350 Trousdale Dr. Chula Vista, Ca. 91910 www.clarksonlab.com A N A L Y T I C A L A N D C O N S U L T I N G C H E M I S T S Date: March 24, 2023 Purchase Order Number: 23-14188 Sales Order Number: 59070 Account Number: GEOE To: *-------------------------------------------------* Geotechnical Exploration Inc. 7420 Trade Street San Diego, CA 92121 Attention: Jay Heiser Laboratory Number: SO9499 Customers Phone: 858-560-0428 Fax: 858-549-1604 Sample Designation: *-------------------------------------------------* One soil sample received on 03/17/23 at 1:15pm, taken from La Bounty 23-14-188 marked as follows: ANALYSIS: Water Soluble Sulfate (SO4) California Test 417 (Turbidity Method) Water Soluble Chloride (Cl) California Test 422 (Titration Method) Sample SO4% Cl% ------------------------- #1 HP-2@3'0.003 0.004 _________________ Rosa Bernal RMB/arr