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HomeMy WebLinkAboutCT 16-07; MARJA ACRES COMMERCIAL; GEOTECHNICAL DESIGN REPORT; 2024-10-28 17991 Fitch • Irvine, California 92614 • PHONE (949) 442-2442 • FAX (949) 476-8322 • www.nmggeotechnical.com October 28, 2024 Project No. 21014-07 To: Arete VP, LLC. 5973 Avenida Encinas, Suite 305, Carlsbad, California 92008 Attention: Mr. Jeff Edinger Subject: Geotechnical Design Report for Commercial Site within the Marja Acres Mixed-Use Development, 4901 El Camino Real, City of Carlsbad, California In accordance with your request, NMG Geotechnical, Inc. (NMG) has performed a geotechnical review of the consistency determination plan package for Marja Acres commercial site. We reviewed Sheets 1 through 23 of 23 sheets on the plan package titled "Marja Acres, 4901 El Camino Real, Carlsbad, CA, 92008." The plan was prepared by Edinger Architects, dated September 6, 2024, and received by NMG on September 29, 2024. NMG is the consultant of record for the Marja Acres mixed-use development and previously performed a subsurface exploration and reviewed the rough grading plan (NMG, 2021b). NMG also provided geotechnical observation and testing during rough grading of the site, which included remedial removals of unsuitable materials, placement of compacted fills and backfill of Mechanically Stabilized Earth (MSE) walls as well as evaluation of settlement monitoring (NMG, 2023a and 2023b). The purpose of our review was to evaluate the proposed improvements with respect to the current and anticipated geotechnical conditions at the site and to provide geotechnical recommendations for design, precise grading, and construction of the proposed commercial development. The recommendations in this report are based on our understanding of existing site conditions, review of the referenced geotechnical reports, review of prior laboratory test data from the site and adjacent areas, geotechnical analysis and review of the subject preliminary grading and utility plan. Based on our review, the proposed minor grading and improvements are considered feasible from a geotechnical standpoint, provided the recommendations in this report are implemented during future design, grading and construction. The primary geotechnical constraint at the site is the potential for highly expansive soils. Design and construction recommendations to mitigate this condition are provided in this report. 21014-07 October 28, 2024 241028 Design Report ii NMG If you have any questions regarding this report, please contact the office. We appreciate the opportunity to provide our services. Respectfully submitted, NMG GEOTECHNICAL, INC. Ted Miyake, RCE 44864 Lynne Yost, CEG 2317 Principal Engineer Principal Engineer FEO/LY/TM/je Distribution: Addressee (E-Mail) CEG No. 2317 21014-07 October 28, 2024 241028 Design Report iii NMG TABLE OF CONTENTS 1.0 INTRODUCTION ...........................................................................................................1 1.1 Purpose and Scope of Services ........................................................................................1 1.2 Site Location, Prior Grading and Existing Conditions ....................................................1 1.3 Proposed Commercial Project ..........................................................................................2 2.0 GEOLOGIC FINDINGS .................................................................................................3 2.1 Summary of Geologic Conditions and Earth Units .........................................................3 2.2 Groundwater ....................................................................................................................3 2.3 Seismic Hazards ...............................................................................................................3 2.4 Geotechnical Soil Characteristics ....................................................................................4 2.5 Settlement and Foundation Considerations .....................................................................4 2.6 Slope Stability ..................................................................................................................5 3.0 CONCLUSIONS AND RECOMMENDATIONS ..........................................................6 3.1. General Conclusion ..........................................................................................................6 3.2 General Earthwork and Grading Standards .....................................................................6 3.3 Pad Preparation ................................................................................................................6 3.4 Groundwater ....................................................................................................................6 3.5 Settlement ........................................................................................................................7 3.6 Foundation and Structural Slab-on-Grade Parameters ....................................................7 3.7 Moisture Mitigation for Concrete Slabs ..........................................................................8 3.8 Seismic Design Parameters ..............................................................................................9 3.9 Lateral Earth Pressures for Retaining Structures .............................................................9 3.10 Foundation Setbacks ......................................................................................................10 3.11 Exterior Concrete (Non-Structural) ...............................................................................11 3.12 Cement Type and Soil Corrosivity ................................................................................13 3.13 Concrete Pavement for Trash Enclosure Area ...............................................................13 3.14 Asphalt Concrete Pavements .........................................................................................13 3.15 Interlocking Concrete Paver Sections ............................................................................14 3.16 Trench Excavation and Backfill .....................................................................................15 3.17 Slope Maintenance, Lot Drainage, and Erosion Control ...............................................16 3.18 Geotechnical Design Review .........................................................................................16 3.19 Geotechnical Observation and Testing ..........................................................................16 4.0 LIMITATIONS ..............................................................................................................18 21014-07 October 28, 2024 241028 Design Report iv NMG ATTACHMENTS Figures Figure 1 – Site Location Map – Rear of Text Figure 2 – Retaining Wall Drainage Detail – Rear of Text Appendices Appendix A – References Appendix B – Laboratory Test Results Appendix C – Seismic Data Appendix D – General Earthwork and Grading Specifications Appendix E -- Geotechnical Grading Plan Review Letter 4/7/25 Appendix F -- Geotechnical Grading Plan Review Letter 9/30/25 21014-07 October 28, 2024 241028 Design Report 1 NMG 1.0 INTRODUCTION 1.1 Purpose and Scope of Services This study was conducted to provide geotechnical recommendations for design and construction of the proposed commercial development in light of the existing geotechnical conditions of the site. The commercial development will consist of two structural areas: Restaurant Retail Pad A on the west side and Retail Pad B on the east side. Our services included the following: • Review of geotechnical reports by NMG including the original Marja Acres design and exploration report (NMG, 2021b) and the report of rough grading issued by NMG following the completion of rough grading (NMG, 2023a). • Review of Marja Acres Consistency Determination Package dated August 2024, prepared by Edinger Architects, received by NMG on September 29, 2024. • Site reconnaissance and collection of soil samples from the two building pads on the site. • Laboratory testing of soil samples for classification, grain size, plasticity (Atterberg limits), expansion index, soluble sulfate content, and corrosivity to metal. • Geotechnical analyses of the collected data. • Preparation of this report. 1.2 Site Location, Prior Grading and Existing Conditions The approximately 1.5-acre site is a portion of the overall Marja Acres development in the City of Carlsbad, which was entitled and rough graded by KB Home and includes attached single family housing and a senior living facility. The subject commercial site is located within the northern portion of the Marja Acres development, adjacent to El Camino Real (Figure 1). The Marja Acres development was explored and evaluated from a geotechnical standpoint for design and construction by NMG in 2021 (NMG, 2021b). The subject commercial site was graded along with the entire Marja Acres development by KB Home under the geotechnical observation and testing of NMG between May and October of 2022. The as-graded geotechnical conditions are summarized in our referenced report (NMG, 2023a). The subject commercial site consists of a vacant graded lot which is currently covered with sparse weed growth, miscellaneous soil stockpiles and construction materials. It is bounded on the north by an approximately 10- to 15-foot high compacted fill slope with a mechanically stabilized earth (MSE) retaining wall that descends to El Camino Real; on the west by Garden Hill Loop street; on the east by recently constructed residential units and along the south by a 2H:1V slope that ascends to additional residential lots. The MSE wall (Anchor Block®) along the toe of the slope adjacent to El Camino Real retains a maximum of 5-feet. A storm water treatment basin with biofiltration materials and a subsurface collection system was constructed during rough grading at the 21014-07 October 28, 2024 241028 Design Report 2 NMG southwest corner of the site, adjacent to Building Pad A. The basin is approximately 5.5 feet deep and was constructed with side slopes with ratios of 2H:1V to 3H:1V. 1.3 Proposed Commercial Project Based on our review of the preliminary site plan, the proposed project consists of two structural pads with a parking lot between them. The elevations across the subject site will range from approximately 69 to 72 feet above mean sea level (msl). Building Pad A is for a future restaurant and Building Pad B is for retail spaces. After the rough grading, we anticipate the proposed precise grading within the subject site will consist of relatively minor cuts and fills, generally less than 1 foot. The consistency determination plan reviewed for this report consists of Sheets 1 through 23 of 23 sheets. Sheets A0-1 through A0-3 are the architectural plans. Sheet C-1 is the civil plan and includes impervious area consistency comparison. Sheets L1 through L4 are the landscape plans. The remaining sheets include preliminary floor and roof plan and elevations for building pads A and B. The reviewed plan provides the following information: • Building footprint locations; • Pad grades for the building pads; • Location of parking lots; • Location of trash enclosure area; and • Sewer and water lines. 21014-07 October 28, 2024 241028 Design Report 3 NMG 2.0 GEOLOGIC FINDINGS 2.1 Summary of Geologic Conditions and Earth Units The subject site is in the Peninsular Range geomorphic province, within the rolling hills of coastal northern San Diego County near Agua Hedionda Lagoon. The proposed commercial development is underlain by compacted fill on the order of 25 to 32 feet thick. The compacted fill was placed during rough grading under the geotechnical observation and testing of NMG (2023a). The majority of the compacted fill is underlain by native alluvium. Locally, sedimentary bedrock of the Santiago Formation underlies the compacted fill at the southeast corner of the site, under a portion of the proposed entry drive and beneath a small section of the southerly boundary of Building Pad B. An existing Kinder Morgan fuel pipeline running parallel to and directly south of El Camino Real was left-in-place during rough grading per the fuel- line owner’s agreement with KB Home. Remedial removals over the pipeline easement were performed in an 8-foot-wide span to within 2 feet of the top of the fuel line. The remaining approximately 2-feet of existing backfill over the pipeline was left-in-place. A small segment of this pipeline is present under a portion of the existing slope and future landscape/hardscape area northwest of Building Pad A. In this landscape/hardscape area, approximately 25 feet of compacted fill overlies the pipeline. The compacted fill generally consists of a mixture of silty/clayey sand, sandy clay, and silty clay. The alluvium was found to be moist to saturated, medium dense/stiff and composed of silty/clayey sand, sandy clay, and silty clay. The Santiago Formation bedrock mapped at the site consisted of silty fine massive sandstone, with occasional, relatively thin clay beds. 2.2 Groundwater Groundwater was encountered during our geotechnical site exploration at an approximate elevation of 37 feet above msl. With the placement of compacted fill to the approximate rough grade elevation of 72 feet above msl, groundwater is on the order of 35 feet deep below the commercial site ground surface. 2.3 Seismic Hazards No major or active faults are mapped at the site (CGS, 2010), the site located within a fault- rupture hazard zone as defined by the Alquist-Priolo Special Studies Zones Act (CGS, 2018) and no evidence of active faulting was observed during rough grading of the subject site (NMG, 2023a). Thus, the potential for fault rupture hazard at the site is considered very low. The closest major active fault to the site is the Rose Canyon/Newport Inglewood Fault zone located approximately 6.2 (9.95 kilometers) miles to the west (offshore). The anticipated primary seismic hazard at the subject site is ground shaking due to regional active faults. Using the USGS deaggregation computer program (2021) and the site coordinates of 33.1511 degrees north latitude and 117.3073 degrees west longitude, the controlling fault for design purposes is the Rose Canyon Fault. This fault is located 9.95 km west of the site with a Maximum Moment Magnitude of 7.0. 21014-07 October 28, 2024 241028 Design Report 4 NMG Seismic design parameters were calculated based on a computer program by the Structural Engineers Association/Office of Statewide Health Planning and Development (2024). The results are presented in Section 3.10 and the data is included in Appendix C. The subject site has low potential for liquefaction, due to the presence of 25 to 32 feet of compacted fill overlying fine-grained native alluvium. Seismic settlement due to liquefaction is generally anticipated to be less than ½-inch. Tsunami and seiche are not considered hazards at this site due to the elevation and the distance of the site from the ocean. No confined bodies of water are located immediately adjacent to the site. 2.4 Geotechnical Soil Characteristics NMG recently collected two bulk samples from the rough graded surface for laboratory testing. The following includes a summary of the soil engineering properties based on the laboratory test results, which are included in Appendix B. Soil Properties: Passing No. 200 sieve tests were conducted and indicate the compacted fill soils have fines contents (passing No. 200 sieve) in the range of 45 to 52 percent. Atterberg limits testing was performed on the two samples. The samples had liquid limits in the range of 34 to 37 percent and plasticity indices in the range of 22 to 23. In general, the soils in the upper 12 inches at commercial site were classified as clay and clayey sand (USCS Classification of CL and SC). The fine-grained materials consisted of low and medium plasticity clays (USCS Classification of CL). Expansion Index: Expansion index testing was performed on two bulk samples during this investigation. Test results indicate that the onsite soils range from low (44) to medium (69) expansion potential. Observations during rough grading and laboratory testing after the completion of rough grading indicated that significant portions of the near surface fill materials within the Marja Acres development have high expansion potential (NMG, 2023a). Corrosivity: Soil corrosivity testing with respect to metals and concrete in contact with earth was determined from a bulk sample in the upper 12 inches feet during the investigation. The soil was tested for chloride, pH, electrical resistivity, and soluble sulfate content. The electrical resistivity test indicates that onsite soils are moderately corrosive to ferrous metals. The soluble sulfate content test results in negligible ("S0") exposure level. Chloride levels were also low. 2.5 Settlement and Foundation Considerations Settlement monitoring of the deeper fills overlying alluvial soils within the Marja Acres development was conducted following rough grading. Three settlement monitoring devices were installed at finished grade and monitored for up to 6 months to verify that settlements of the compacted fill placed over alluvium were within acceptable limits. Survey data collected from the settlement monitoring devices indicated that the remaining settlement of the left-in-place alluvium was either substantially complete or less than anticipated. The subject site was released for 21014-07 October 28, 2024 241028 Design Report 5 NMG development from a settlement standpoint in February 2023 (NMG, 2023c). With the remedial grading of rough grading and the generally fine-grained left-in-place alluvium, seismic settlements are expected to be less than ½-inch. 2.6 Slope Stability Manufactured fill slopes constructed adjacent to the site were observed and tested by NMG to confirm were constructed in accordance with our recommendations and the grading code of the City of Carlsbad. Graded slope conditions were reported in detail in the report of rough grading (NMG, 2023a). The slopes adjacent to the subject site are considered grossly and surficially stable. 21014-07 October 28, 2024 241028 Design Report 6 NMG 3.0 CONCLUSIONS AND RECOMMENDATIONS 3.1. General Conclusion Based on our review, the subject commercial site is considered geotechnically feasible. The following preliminary recommendations should be implemented during structural design, grading, and construction. Our recommendations are considered minimum and may be superseded by more stringent requirements of others (i.e., governing agency, architect, and/or the project structural engineer). Additional or revised recommendations may be provided once plans or additional design information are available for review. 3.2 General Earthwork and Grading Standards Future precise grading and construction excavations should be performed in accordance with the requirements of the City of Carlsbad and the General Earthwork and Grading Specifications, which are included in Appendix D. Miscellaneous trash, debris, vegetation, and stockpiled fill (if any) should be removed. If construction begins within the next 3 to 4 months, only re-processing of the near surface soils is anticipated. If construction is delayed beyond that time, removal and recompaction of more of the near surface soil may be necessary. The geotechnical consultant should evaluate the site conditions prior to construction to evaluate the need for remedial earthwork. After re-processing of the site and prior to the placement of additional fill, the exposed compacted fill materials should be scarified and moisture conditioned. Fill materials should be compacted to at least 90 percent of maximum dry density, as determined by ASTM Test Method D1557. Fill materials should be placed in loose lifts, no thicker than approximately 8 inches. Materials should be moisture-conditioned and processed, as necessary, to achieve uniform moisture content that is within moisture limits required to assure adequate bonding and compaction. We recommend that moisture contents of the fill be 2 to 3 percent over the optimum moisture content, because of the expansive nature of the materials and in order to reduce the time required for presaturation of subgrades for concrete improvements. 3.3 Pad Preparation During precise grading, the ground surface consisting of engineered fill should be reprocessed as- needed to reestablish proper moisture and compaction and must be accepted by the geotechnical consultant prior to placement of any new compacted fill. 3.4 Groundwater Groundwater at the site is anticipated to remain more than 25 feet deep below the improvements. No special subdrainage measures are considered necessary related to groundwater. 21014-07 October 28, 2024 241028 Design Report 7 NMG 3.5 Settlement Based on our assessment of the site grading and soil conditions and the proposed buildings and structures, we anticipate that the total and differential settlement will be on the order of 1 inch and ½ inch over a span of 40 feet, respectively. Seismic settlements in the event of the design earthquake are expected to be less than ½-inch as discussed in Section 2.5. 3.6 Foundation and Structural Slab-on-Grade Parameters The foundation soils potentially may have high expansion potential and should be designed accordingly. The sizing of commercial building foundations embedded in engineered fill may be based on a net allowable bearing capacity of 1,000 psf may be assumed for a 12-inch-wide footing embedded 12 inches below the lowest adjacent grade. The allowable bearing pressure may be increased by 300 psf for every additional foot of width and by 700 psf for every additional foot of embedment depth up to a maximum of 4,000 psf. The net allowable bearing pressure may be increased by one-third for wind and seismic loading. For resistance against sliding, a friction coefficient of 0.35 may be used for the soil-concrete slab interface. A passive lateral earth pressure (equivalent fluid pressure) of 330 psf/ft. may be used for lateral resistance. The friction and passive resistance values may be combined without reduction. The above values may be increased for structures, such as retaining walls, which can tolerate greater differential settlements. The footings of freestanding structures (including walls and pilasters) should have a minimum embedment depth of 24 inches into approved soils. A soil unit weight of 120 pcf may be assumed for onsite materials. For non-post-tensioned slabs-on-grade and foundations, in accordance with Wire Reinforcement Institute (WRI) method (per the 2022 California Building Code), an effective Plasticity Index of 30 is considered appropriate for the upper 15 feet of soil materials. A subgrade modulus (k) of 50 pci and a modulus of elasticity (Es) of 1,000 psi may be assumed. Foundation and slab-on-grade subgrades should have a minimum moisture content of 1.3 times the optimum moisture content (per ASTM D1557) to a minimum depth of 18 inches below finish pad grade. The slabs should also be designed to satisfy the settlement criteria presented in Section 3.5. For design of the pole-type foundations (i.e., light poles, shade structures, etc.), an allowable soil-bearing pressure (S1) of 360 psf/ft may be used for Equation 18-1 (the "pole" equation) of the 2022 California Building Code (CBC) Section 1807.3.2.1 to determine the depth of embedment for the footings, considering level ground conditions. The equation is applicable for designed embedment depths of less than 12 feet for the purpose of computing lateral pressure. Also, for vertical loads on pole-type foundations, an allowable skin friction of 250 pounds per square foot may be used. For cast- in-place pole-type foundations, the vertical end bearing pressure should be neglected. 21014-07 October 28, 2024 241028 Design Report 8 NMG 3.7 Moisture Mitigation for Concrete Slabs In addition to geotechnical and structural considerations, the project owner should consider interior moisture mitigation when designing and constructing slabs-on-grade. The intended use of the interior space, type of flooring, and the type of goods in contact with the floor may dictate the need for, and design of, measures to mitigate potential effects of moisture emission from and/or moisture vapor transmission through the slab. Typically, for human occupied structures, a vapor retarder or barrier is utilized under the slab to help mitigate moisture transmission through slabs. The location of the vapor retarder is subject to the builder's past successful practice; placement of 1 or 2 inches of sand (or granular fill material) over the moisture retardant has been common practice by builders in southern California. Per Section 7.2 of ACI 302.2 R-06, the benefits of a granular layer include reducing the potential for the following: • Concrete shrinkage cracks and slab curling during drying; • Puncturing the vapor retarder; • Surface blistering or delamination caused by an extended concrete bleeding period; and • Settlement cracking over reinforcing steel. The current guidelines by the American Concrete Institute (ACI 302.1R-04 and 302.2 R-06) allows the vapor retarder to be placed directly under the slab (with no granular fill layer). If the concrete slab is placed directly on the vapor retarder/barrier, a low shrinkage mix design and other construction measures (i.e., better curing, reduced joint spacing, etc.) are required. Per Section 7.2 of ACI 302.2 R-06 the following are some benefits of placing the concrete directly on the vapor retarder: • Reduced cost because of less excavation and no need for additional granular materials; • Better curing of the slab bottom because the vapor retarder minimizes moisture loss; and • Less chance of floor moisture problems caused by moisture being trapped in the granular layer. Specifying the strength of the retarder to resist puncture and its permeance rating is important. These qualities are not necessarily a function of the retarder thickness. A minimum of 10-mil is typical but some materials, such as 10-mil polyethylene ("Visqueen"), may not meet the desired standards for toughness and permeance. The vapor retarder, when used, should be installed in accordance with standards such as ASTM E 1643 (and/or those specified by the manufacturer), including proper perimeter sealing. Concrete mix design and curing are also significant factors in mitigating slab moisture problems. Concrete with lower water/cement ratios (with higher compressive strength) results in denser, less permeable slabs. They also "dry" faster regarding when flooring can be installed (reduced moisture emissions quantities and rates). Rewetting of the slab following curing should be avoided since this can result in additional drying time required prior to flooring installation. Proper concrete slab testing prior to flooring installation is also important. Concrete mix design, the type and location of the vapor retarder should be determined in coordination with all parties involved in the finished product, including the project owner, 21014-07 October 28, 2024 241028 Design Report 9 NMG architect, structural engineer, geotechnical consultant, concrete subcontractors, and flooring subcontractors. 3.8 Seismic Design Parameters The following table summarizes the seismic design criteria for the subject site. The seismic design parameters are developed in accordance with 2022 CBC and ASCE 7-16, including Supplement Nos. 1 through 3. Selected Seismic Design Parameters from 2022 CBC/ASCE 7-16 Seismic Design Values Reference Latitude 33.1511 North Longitude 117.3073 West Controlling Seismic Source Rose Canyon Fault USGS, 2024 Distance to Controlling Seismic Source 10.0 Miles (6.2 km) USGS, 2024 Site Class per Table 20.3-1 of ASCE 7-16 D Ss, Spectral Acceleration for Short Periods 0.99 g SEA/OSHPD, 2024 S1, Spectral Accelerations for 1-Second Periods 0.36 g SEA/OSHPD, 2024 Fa, Site Coefficient, Table 11.4-1 of ASCE 7-16 1.10 SEA/OSHPD, 2024 Fv, Site Coefficient, Table 11.4-2 of ASCE 7-16 1.94 SDS, Design Spectral Response Acceleration at Short Periods from Equation 11.4-3 of ASCE 7-16 0.73 g SEA/OSHPD, 2024 SD1, Design Spectral Response Acceleration at 1-Second Period from Equation 11.4-4 of ASCE 7-16 0.70 g* TS, SD1/ SDS, Section 11.4.6 of ASCE 7-16 0.96 sec* TL, Long-Period Transition Period 8 sec SEA/OSHPD, 2024 PGAM, Peak Ground Acceleration Corrected for Site Class Effects from Equation 11.8-1 of ASCE 7-16 0.51 g SEA/OSHPD, 2024 Seismic Design Category, Section 11.6 of ASCE 7-16 D *These values have been increased by 50% as outlined in Supplement No. 3 of ASCE 7-16 Chapter 11.4.8. 3.9 Lateral Earth Pressures for Retaining Structures Preliminary recommendations for lateral earth pressures for retaining walls and structures (if any) with approved onsite drained soils are as follows: Lateral Earth Pressures Equivalent Fluid Pressure (psf/ft.) Conditions Level 2:1 Slope Active 45 70 At Rest 65 90 Passive 320 160 (if sloping in front of wall) 21014-07 October 28, 2024 241028 Design Report 10 NMG These parameters are based on a soil internal friction angle of 28 degrees and soil unit weight of 120 pcf. The above parameters do not apply for backfill that is highly expansive. Drainage behind retaining walls should also be provided in accordance with the attached figure (Figure 2). To design an unrestrained retaining wall, such as a cantilever wall, the active earth pressure may be used. For a restrained retaining wall, the at-rest pressure should be used. Passive pressure is used to compute lateral soils resistance developed against lateral structural movement. The passive pressures provided above may be increased by one-third for wind and seismic loads. Passive resistance is considered only if it is ensured that the soil against embedded structure will remain intact with time. Future landscaping/planting and improvements adjacent to the retaining walls should also be considered in the design of the retaining walls. Excessive soil disturbance, trenches (excavation and backfill), future landscaping adjacent to footings and over-saturation can adversely impact retaining structures and result in reduced lateral resistance. For walls with narrow trench footings (10 inches or less) that are in areas likely to be landscaped, we recommend neglecting the passive resistance in the upper 1 foot. For sliding resistance, the friction coefficient of 0.35 may be used at the concrete and soil interface. The coefficient of friction may also be increased by one-third for wind and seismic loading. Passive and friction resistance may be combined without reduction. The retaining walls may also need to be designed for additional lateral loads if other structures or walls are planned within a 1H:1V projection. The seismic lateral earth pressure for walls retaining more than 6 feet of soil and level backfill conditions may be estimated to be an additional 14 pcf for active and at-rest conditions. The earthquake soil pressure has a triangular distribution and is added to the static pressures. For the active and at-rest conditions, the additional earthquake loading is zero at the top and maximum at the base. The seismic lateral earth pressure does not apply to walls retaining less than, or equal to, 6 feet of soil (2022 CBC Section 1803.5.12). 3.10 Foundation Setbacks The footings of structures located above descending slopes should be set back from the slope face in accordance with the minimum requirements of the City of Carlsbad and CBC criteria, whichever is greater. The setback distance is measured from the outside edge of the footing bottom along a horizontal line to the face of the slope. 21014-07 October 28, 2024 241028 Design Report 11 NMG The tables below summarize the minimum setback criteria for structures above descending slopes: Structural Setback Requirements Case A – Building and Retaining Wall Footings Above Descending Slopes Slope Height [H] (feet) Minimum Setback from Slope face (feet) Less than 10 5 10 to 20 ½ * H 20 to 30 10 More than 30 ⅓ * H (maximum of 40') Case B – Freestanding Wall Footings Above Descending Slopes Slope Height [H] (feet) Minimum Setback from Slope face (feet) Less than 10 5 10 to 20 ½ * H More than 20 Maximum of 10 For freestanding walls and other structures that are sensitive to lateral movement (e.g., smooth stucco finish, glass screens, etc.), NMG recommends that the structural setback requirements in accordance with Case A above be followed or that additional design measures be used to help control the potential for cracking and displacements. Otherwise, typical freestanding walls may have a setback in accordance with Case B. 3.11 Exterior Concrete (Non-Structural) Exterior concrete elements such as curbs and gutters, driveways and sidewalks are susceptible to lifting and cracking when constructed over expansive soils. With expansive soils, the impacts to flatwork/hardscape can be significant, often requiring removal and replacement of the affected improvements. Please also note that reducing concrete problems is often a function of proper slab design; concrete mix design, placement, and curing/finishing practices. Adherence to guidelines of the American Concrete Institute (ACI) is recommended. Also, the amount of post-construction watering, or lack thereof, can have a very significant impact on the adjacent concrete flatwork. For reducing the potential effects of expansive soils, we recommend a combination of presaturation of subgrade soils; reinforcement; moisture barriers/drains; and a sublayer of granular material. Though these types of measures may not eliminate adverse impacts, application of these measures can significantly reduce the impacts from post-construction expansion of soil. The degrees and combinations of these measures will depend upon: • The expansion potential of the subgrade soils; • The potential for moisture migration to the subgrade; 21014-07 October 28, 2024 241028 Design Report 12 NMG • The feasibility of the measures (especially presaturation); and • The economics of these measures versus the benefits. These factors should be weighed by the project owner determining the measures to be applied on a project-by-project basis, subject to the requirements of the local building/grading department. The following table provides our recommendations for varying expansion characteristics of subgrade soils. Additional considerations are also provided after the table. Although the expansion index tests for the commercial site were in the low to medium categories, we recommend that the "High" category be used during design and construction due to the significant potential for more expansive soils as described in Section 2.4. TYPICAL RECOMMENDATIONS FOR CONCRETE FLATWORK/HARDSCAPE Expansion Potential (Index) Recommendations Very Low (<20) Low (21 – 50) Medium (51 – 90) High (91 – 130) Very High (> 130) Slab Thickness (Min.): Nominal thickness except where noted. 4" 4" 4" 4" 4" Full Subbase: Thickness of sand or gravel layer below concrete N/A N/A Optional 2" – 4" 2" – 4" Presaturation: Degree of optimum moisture content (opt.) and depth of saturation Pre-wet Only 1.1 x opt. to 6" 1.2 x opt. to 12" 1.3 x opt. to 18" 1.4 x opt. to 24" Joints: Maximum spacing of control joints. Joint should be ¼ of total thickness 10' 10' 8' 6' 6' Reinforcement: Rebar or equivalent welded wire mesh placed near mid-height of slab N/A N/A Optional (WWF 6 x 6 – W1.4xW1.4) No. 3 rebar, 24" O.C. both ways or equivalent wire mesh No. 3 rebar, 24" O.C. both ways Restraint: Slip dowels across cold joints; between sidewalk and curb N/A N/A Optional Across cold joints Across cold joints (and into curb) The more expansive soils, because they are clayey, can take significantly longer to achieve recommended presaturation levels. Therefore, the procedure and timing should be carefully planned in advance of construction. For exterior slabs, the use of a granular sublayer is primarily intended to facilitate presaturation and subsequent construction by providing a better working surface over the saturated soil. It also helps retain the added moisture in the native soil in the event that the slab is not placed immediately. Where these factors are not significant, the layer may be omitted. On projects with highly expansive soils, additional measures, such as thickened concrete edges/footings, subdrains and/or moisture barriers, should be considered where planter or natural 21014-07 October 28, 2024 241028 Design Report 13 NMG areas with irrigation are located adjacent to the concrete improvements. Design and maintenance of proper surface drainage is also very important. If the concrete will be subject to heavy loading from cars/trucks or other heavy objects, thicker slabs should be used. The above recommendations typically are not applied to curbs and gutters but should be considered in areas with highly expansive soils. 3.12 Cement Type and Soil Corrosivity Based on laboratory testing, soluble sulfates exposure in the onsite soils may be classified as "S0" per Table 19.3.1.1 of ACI-318-14. Structural concrete elements in contact with soil include footings and building slabs-on-grade. The flatwork and sidewalk concrete are typically not considered structural elements. Concrete mix for these elements may also be based on the "S0" soluble sulfate exposure class of Table 19.3.2.1 in ACI-318-14. Chloride contents were negligible. Onsite soils are anticipated to be corrosive to ferrous metals. Laboratory test results are included in Appendix B of this report. Other ACI guidelines for structural concrete are recommended. 3.13 Concrete Pavement for Trash Enclosure Area For concrete pavement within a trash enclosure area, we recommend 6 inches of concrete, reinforced with No. 3 rebar at 18 inches on-center, both ways, over 4 inches of AB over compacted subgrade. Alternatively, the section may consist of 7 inches of concrete, reinforced with No. 3 rebar at 18 inches on-center, both ways, over compacted subgrade. Prior to construction of concrete pavement, the subgrade soils should be scarified to a minimum depth of 6 inches, moisture-conditioned as needed for expansive soils, and recompacted in-place to a minimum of 90 percent relative compaction (per ASTM D1557). Due to the potential for highly expansive soils the subgrades for the optional 7-inch section should not be compacted to 95 percent relative compaction which is typical. 3.14 Asphalt Concrete Pavements Based on an assumed design R-value of 5 and estimated traffic indices (TIs), we recommend the following preliminary pavement sections: Street Location Estimated Traffic Index(Tis) Pavement Section Main Drives TI – 6.0 0.35' AC / 1.00'AB or 0.40' AC / 0.85' AB or 0.50' AC / 0.60' AB Private Courts TI – 5.0 0.35' AC / 0.50' AB Parking Stalls TI – 4.0 0.25' AC / 0.50' AB AC = Asphalt Concrete, AB = Aggregate Base 21014-07 October 28, 2024 241028 Design Report 14 NMG Please note that for two-stage paving operations, we recommend that the final AC cap be a minimum of 0.10 foot thick and the base AC course has a minimum thickness of 0.25 foot. Asphalt concrete pavement should be placed in accordance with the requirements of Sections 301 and 302 of the Standard Specifications of Public Works Construction (the Greenbook). Prior to construction of pavement sections, the subgrade soils should be scarified to a minimum depth of 6 inches, moisture conditioned as needed, and recompacted in place to a minimum of 90 percent relative compaction (per ASTM D1557). Subgrade should be firm prior to AB placement. AB materials can be crushed aggregate base or crushed miscellaneous base in accordance with the Greenbook (Section 200-2). The materials should be free of any deleterious materials. Aggregate base materials should be placed in 6- to 8-inch loose lifts, moisture-conditioned as necessary, and compacted to a minimum of 95 percent relative compaction (per ASTM D1557). Asphalt concrete should also be compacted to a minimum relative compaction of 95 percent. Unpaved median and parkway areas should be provided with moisture barrier per the City of Irvine standard plans. 3.15 Interlocking Concrete Paver Sections The following recommendations should be implemented during construction of concrete pavers: Pedestrian Flatwork Driveways Drive Areas (Motor Courts) 60-millimeter-thick concrete paver over approximately 1 inch of sand over a minimum of 4 inches of concrete reinforced with No. 3 bars at 24 inches on center or equivalent wire mesh over subgrade. The concrete low pour may be replaced with 6 inches of aggregate base (AB) over compacted subgrade or 4 inches of AB over a layer of geofabric (Mirafi 500X or equivalent) over compacted subgrade. 80-millimeter-thick concrete paver over approximately 1 inch of sand over a minimum of 4 inches of concrete reinforced with No. 3 bars at 24 inches on center or equivalent wire mesh over subgrade. The concrete low pour may be replaced with 6 inches of AB over compacted subgrade or 4 inches of AB over a layer of geofabric (Mirafi 500X or equivalent) over compacted subgrade. 80-millimeter-thick concrete paver over approximately 1 inch of sand over a minimum of 5 inches of concrete reinforced with No. 3 bars at 24 inches on center or equivalent wire mesh. The concrete low pour may be replaced with 10 inches of AB over compacted subgrade or 8 inches of AB over a layer of geofabric (Mirafi 600X or equivalent) over compacted subgrade. A concrete band along the perimeter of the pavers should be provided for lateral restraint. The concrete band should, at minimum, be 12 inches deep and deepened to below the depth of disturbed soil, if adjacent to landscape/planter areas. Also, a drainage system consisting of a 2-inch PVC drainage pipe should be installed at the low end of the concrete low pour at 10-foot intervals through the slab and filled with pea gravel. The PVC drainage pipe should drain to a minimum of 6-inch-diameter by 12-inch-deep drain pit filled with pea gravel below the pipe. The paver surfaces should slope away from structures a minimum of 21014-07 October 28, 2024 241028 Design Report 15 NMG 2 percent. The concrete underlayment for the drive areas should be provided with weakened plane joints at maximum 15-foot intervals. If the pavers are to be set in mortar or are underlain with AB, this drainage system is not required. Prior to construction of the paver sections, the subgrade soils should be scarified to a minimum depth of 6 inches, moisture conditioned as needed, and recompacted in place to a minimum of 90 percent relative compaction. 3.16 Trench Excavation and Backfill Excavations should conform to all applicable safety requirements and should be performed in accordance with the requirements set forth by Cal/OSHA Excavation Safety Regulations (Construction Safety Orders, Section 1504, 1539 through 1547, Title 8, California Code of Regulations). The onsite compacted fill soils may be classified as Type "B" for Cal/OSHA trench excavation requirements. Cal/OSHA regulations indicate that, for workmen in confined conditions, the steepest allowable slopes in Type "B" soils are 1:1 (horizontal to vertical) for excavations less than 20 feet deep. The contractor’s qualified person should periodically review excavations to confirm compliance with Cal/OSHA requirements. Trenches deeper than 20 feet require specific evaluation/analysis by a shoring engineer and the geotechnical consultant. Trench excavations adjacent to structures should conform to any clearance requirements on the grading and foundation plans. Trenches excavated on a graded slope-face should be properly backfilled and compacted in order to obtain a minimum 90 percent relative compaction to the slope face. Trenches excavated next to structures and foundations should also be properly backfilled and compacted to provide full lateral support and reduce settlement potential. Native soils should be suitable for use as trench backfill. Native backfill materials should be compacted to a minimum of 90 percent relative compaction (per ASTM D1557). Select granular backfill (i.e., clean sand with SE 30 or better) may be used in lieu of native soils, but should also be compacted or densified with water jetting and flooding. Trenches excavated next to structures and foundations should also be properly backfilled and compacted to provide full lateral support and reduce settlement potential. Pipelines should be bedded and shaded in accordance with the Greenbook. If high-density polyethylene (HDPE) pipe is planned, the excavation, installation, bedding, shading and backfilling should be in strict accordance with the project and manufacturer's requirements. HDPE pipe has specific requirements for the width of the trench excavation. Also, HDPE pipe requires appropriate bedding and compaction of select granular backfill material in the pipe zone to provide uniform and adequate support. 21014-07 October 28, 2024 241028 Design Report 16 NMG 3.17 Slope Maintenance, Lot Drainage, and Erosion Control Maintaining adequate surface drainage, proper disposal of run-off water, and control of irrigation will help reduce the potential for future moisture-related problems and differential movements from soil heave/settlement. Surface drainage should be carefully taken into consideration during grading, landscaping, and building construction. Positive surface drainage should be provided to direct surface water away from structures and slopes and toward the street or suitable drainage devices. Ponding of water adjacent to the structures should not be allowed. Buildings should have roof gutter systems, and the run-off should be directed to parking lot/street gutters by area drain pipes or by sheet flow over paved areas. Paved areas should be provided with adequate drainage devices, gradients, and curbing to prevent run-off flowing from paved areas onto adjacent unpaved areas. Considering the climatic conditions in southern California and the expansive soil mitigation measures provided herein, a two-percent slope away from structures should be provided which is in substantial compliance with the 2019 CBC. Also, the swales with one-percent slopes are acceptable from our geotechnical standpoint and are common practice in this locale. Construction of planter areas immediately adjacent to structures should be avoided if possible. If planter boxes are constructed adjacent to or near buildings, the planters should be provided with controls to prevent excessive penetration of the irrigation water into the foundation and flatwork subgrades. Provisions should be made to drain excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. Raised planter boxes may be drained with weepholes. Deep planters (such as palm tree planters) should be drained with below-ground, water-tight drainage lines connected to a suitable outlet. Moisture barriers should also be considered. It is also important to maintain a consistent level of soil moisture, not allowing the subgrade soils to become overly dry or overly wet. Properly designed landscaping and irrigation systems can help in that regard. 3.18 Geotechnical Design Review Future foundation, precise grading, wall, and landscape architectural plans should be reviewed by the geotechnical and accepted by the consultant prior to precise grading. Additional recommendations may be necessary and provided with those reviews. 3.19 Geotechnical Observation and Testing At minimum, geotechnical observation and testing should be conducted during grading at the following stages: • During site preparation and clearing, prior to site processing; • During precise grading and placement of additional fill (if any); 21014-07 October 28, 2024 241028 Design Report 17 NMG • Upon completion of any foundation excavations prior to placement of reinforcement or concrete; • During subgrade preparation for buildings and hardscape; • Upon completion of subgrade presaturation for buildings and hardscape; • During parking lot concrete paver and pavement section construction; • During construction of subdrains and deck drains; • During excavation and backfill for utility trenches; and • When any unusual or unexpected soil and/or geotechnical conditions are encountered during grading and construction. 21014-07 October 28, 2024 241028 Design Report 18 NMG 4.0 LIMITATIONS This report has been prepared for the exclusive use of our client, Arete VP, LLC., within the specific scope of services requested by our client for the design and construction of the subject site. This report or its contents should not be used or relied upon for other projects or purposes or by other parties without the written consent of NMG. Our methodology for this study is based on local geotechnical standards of practice, care, and requirements of governing agencies. No warranty or guarantee, express or implied is given. The findings, conclusions, and recommendations are professional opinions based on interpretations and inferences made from geologic and engineering data from specific locations and depths, observed or collected at a given time. By nature, geologic conditions can be very different in between points and can also change over time. Our conclusions and recommendations are subject to verification and/or modification with more exploration and/or during grading and construction when more subsurface conditions are exposed. NMG's expertise and scope of services did not include assessment of potential subsurface environmental contaminants or environmental health hazards. 0 250 500 N ---i:====:iFeet A 1 inch =500 feet Q) :51------------------------------------------------1 1: ~ SITE LOCATION MAP Q) a5 ~1---------------------------------------...---------1 r--0 '<I' ~ 0 ~ S:! N 0 S::I MARJAACRES COMMERCIAL SITE 4901 EL CAMINO REAL CITY OF CARLSBAD, CALIFORNIA Project Number: 21014-07 By: TM/LY Project Name: AVP/Marja Acres Commercial Date: 10/28/2024 Figure 1 ~ NMG a.: ______________________________________ .._ ____ _ NMG Geotechnical, Inc.RETAINING WALL DRAINAGE DETAIL 1' Cover 3+" 3+" NOTES:1. PIPE TYPE SHOULD BE PVC OR ABS, SCHEDULE 40 OR SDR35 SATISFYING THE REQUIREMENTS OF ASTM TEST STANDARDD1527, D1785, D2751 , OR D3034.2. FILTER FABRIC SHALL BE APPROVED PERMEABLE NON-WOVEN POLYESTER, NYLON, OR POLYPROPYLENE MATERIAL.3. DRAIN PIPE SHOULD HAVE A GRADIENT OF 1 PERCENT MINIMUM.4. WATERPROOFING MEMBRANE MAY BE REQUIRED FOR A SPECIFIC RETAINING WALL (SUCH AS A STUCCO OR BASEMENT WALL).5. WEEP HOLES MAY BE PROVIDED FOR LOW RETAINING WALLS (LESS THAN 3 FEET IN HEIGHT) IN LIEU OF A VERTICAL DRAINAND PIPE AND WHERE POTENTIAL WATER FROM BEHIND THE RETAINING WALL WILL NOT CREATE A NUISANCE WATERCONDITION. IF EXPOSURE IS NOT PERMITTED, A PROPER SUBDRAIN OUTLET SYSTEM SHOULD BE PROVIDED.6. IF EXPOSURE IS PERMITTED, WEEP HOLES SHOULD BE 2-INCH MINIMUM DIAMETER AND PROVIDED AT 25-FOOT MAXIMUMSPACING ALONG WALL. WEEP HOLES SHOULD BE LOCATED 3+ INCHES ABOVE FINISHED GRADE.7. SCREENING SUCH AS WITH A FILTER FABRIC SHOULD BE PROVIDED FOR WEEP HOLES/OPEN JOINTS TO PREVENT EARTHMATERIALS FROM ENTERING THE HOLES/JOINTS.8. OPEN VERTICAL MASONRY JOINTS (I.E., OMIT MORTAR FROM JOINTS OF FIRST COURSE ABOVE FINISHED GRADE) AT 32-INCHMAXIMUM INTERVALS MAY BE SUBSTITUTED FOR WEEP HOLES.9 THE GEOTECHNICAL CONSULTANT MAY PROVIDE ADDITIONAL RECOMMENDATIONS FOR RETAINING WALLS DESIGNED FOR SELECT SAND BACKFILL. 3/21 RETAINING WALL DRAINAGE.ai AGGREGATE SYSTEM DRAIN COMPOSITE DRAINAGE SYSTEM Weep Hole (optional) Native backfill Native backfill Clean sand vertical drain having sand equivalentof 30 or greater or other free-draining granularmaterial Mirafi G100N, Contech C-Drain 15K, or equivalentdrainage composite. Alternative: Class 2 permeablefilter material (Per Caltransspecifications) may be used forvertical drain and aroundperforated pipe (without filter fabric)Minimum 1 ft.3/ft. of 1/4 to 1 1/2" size gravelor crushed rock encased in approvedFilter Fabric 4-inch diameter perforated pipe with properoutlet. (See Notes below for alternate dischargesystem) 4-inch diameter perforated pipe with proper outlet.Peel back the bottom fabric flap,place pipe next to core,wrap fabric around pipe and tuck behind core. (See Notesfor alternate weep hole discharge system) Cut back of core to match size ofweep hole. Do not cut fabric. Waterproofing (optional) Retaining wall Retaining wall Wrap filter fabricflap behind core Provide proper surface drainage(drain separate from subdrain) Provide proper surface drainage(drain separate from subdrain) 1' to 2' Cover RetainedHeight 1'min. Weep Hole (optional) OPTION 1: OPTION 2: NOTE: DRAINAGE SYSTEM NOT REQUIRED FORWALLS WITH RETAINED HEIGHT OF 30 INCHES OR LESS NOTE: DRAINAGE SYSTEM NOT REQUIRED FORWALLS WITH RETAINED HEIGHT OF 30 INCHES OR LESS FIGURE 2 ____i_ L_ NMG G\@:@ft@:C<::~lf1lllC<::@lt ilf1lC<::o 3/21 RETAINING WALL DRAINAGE.al APPENDIX A 21014-07 October 28, 2024 241028 Design Report A-1 NMG APPENDIX A REFERENCES California Geological Survey (CGS), 2010, Fault Activity Map of California and Adjacent Areas (Scale 1: 750,000), Geologic Data Map No. 6, Compiled and Interpreted by Charles W. Jennings and William A. Bryant. California Geological Survey (CGS), 2018, Earthquake Fault Zones, A Guide for Government Agencies, Property Owners / Developers, and Geoscience Practitioners 2018 for Assessing Fault Rupture Hazards in California, Special Publication 42, Revised. Kennedy, M.P, Tan, S.S., Bovard, K.R., Alverez, R.M., Watson, M.J. and Gutierrez, C.I., 2007, Geologic Map of the Oceanside 30x60 minute Quadrangle, California, California Geological Survey Regional Geologic Map No. 2, Scale 1:100,000. NMG Geotechnical, Inc. 2021a, Geotechnical Due Diligence Study for Marja Acres Development, 4901 El Camino Real, Carlsbad, County of San Diego, California, Project No. 21014- 01, dated February 18, 2021. NMG Geotechnical, Inc., 2021b, Supplemental Geotechnical Investigation and Review of 40- Scale Grading Plan for Proposed Marja Acres Mixed Use Development, 4901 El Camino Real, City of Carlsbad, County of San Diego, California, Project No. 21014- 01, dated July 26, 2021. NMG Geotechnical, Inc., 2023a, Geotechnical Report of Observation and Testing during Rough Grading, Marja Acres Mixed-Use Development, Carlsbad Tract No. 16-07, 4091 El Camino Real, City of Carlsbad, County of San Diego, California, Project No. 21014-02, dated January 18, 2023. NMG Geotechnical, Inc., 2023b, Settlement Release for Rough Grade Lot 2, Commercial Site, Marjia Acres Mixed-Use Development, Carlsbad Tract 16-07, 4091 El Camino Real, City of Carlsbad, County of San Diego, California, Project No. 21014-02, dated February 23, 2023. Structural Engineers Association/Office of Statewide Health Planning and Development, 2024, U.S. Seismic Design Maps, web site address: https://seismicmaps.org/ ; Date Accessed: October 21, 2024. U.S. Geological Survey, 2024, Unified Hazard Tool, Updated NSHM 2014 Dynamic Deaggregation Program; web site address: https://earthquake.usgs.gov/hazards/interactive/ ; Date Accessed: October 21, 2024. APPENDIX B EI-1 Bldg A 0.0 1.0 52 37 22 CL 69 EI-2 Bldg B 0.0 1.0 45 34 23 SC 44 CC Printed: 10/21/24; Template: SUM_SOIL_LAB_ALL; Proj ID: 21014-07.GPJ Arete Venture Partners / Marja Commercial Carlsbad, CA Sheet 1 of 1 Project Number: 21014-07 APPENDIX B SUMMARY OF SOIL LABORATORY DATA Boring/Sample Information BoringNo.SampleNo.Depth(feet) (feet) RemarksSolubleSulfate Content (% by wt) R-ValueExpansion Index Compaction OptimumMoistureContent(%)Depth MaximumDryDensity(pcf)Count(N) Direct Shear Peak FrictionAngle ( )Cohesion(psf)Friction Ultimate Angle ( )Cohesion(psf) USCSGroupSymbol(%) AtterbergLimits LL(%)PIContent(% pass.2µ) HydrometerFines o o Blow Clay Sieve/ Content(% pass.#200) DegreeofSat. (%) FieldDryDensity(pcf) FieldMoistureContent(%) Field Density(pcf) WetEnd (feet)Elevation Geotechnical, Inc.~ NMG __ ~====================== 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001,000 36 SIEVE OPENING IN INCHES 100 200 PE R C E N T P A S S I N G U.S. STANDARD PARTICLE SIZE DISTRIBUTION CL SC Passing 2µ (%) Passing Sieve (%) 52 45 CActivity PI/-2µMoistureSampleDepth (feet) BOULDERS COBBLES GRAVEL coarse LL 37 34 Field 22 23 6 SILT OR CLAY 1-1/2 3/4 3/8 fine PARTICLE SIZE (mm) Symbol USCSNo. 200cCuPI (%) SAND fine U.S. STANDARD SIEVE NUMBERS HYDROMETER 12 8 coarse medium 3 50416 30 Boring Number EI-1 EI-2 Number Bldg A Bldg B 0.0 - 1.0 0.0 - 1.0 Arete Venture Partners / Marja Commercial Carlsbad, CA PROJECT NO. 21014-07 Template: NMSIV; Prj ID: 21014-07.GPJ; Printed: 10/21/24 Geotechnical, Inc. I I I I II I I I I II I I I 0 IZI ~ NMG--======= 0 10 20 30 40 50 60 70 0 20 40 60 80 100 120 PLASTICITY CHART LIQUID LIMIT(%) PL A S T I C I T Y I N D E X ( % ) A-LINEU-LINE ML or OLCL- ML 16 7 4 CL or OL MH or OH CH or OH Arete Venture Partners / Marja Commercial Carlsbad, CA PROJECT NO. 21014-07 Template: NMATT; Prj ID: 21014-07.GPJ; Printed: 10/21/24 Geotechnical, Inc. Symbol LL 37 34 PassingNo. 200 Sieve (%) 52 45 Description Number Yellowish brown silty sandy CLAY Brown silty clayey SAND USCS CL SC PI 22 23 Boring EI-1 EI-2 Number Sample Depth (feet) Bldg A Bldg B 0.0 - 1.0 0.0 - 1.0 / ,/ V ••••• /:'::/ /:J\:::: :/::::::::7 17 I 0 IZI ~ NMG--================= Sample Compacted Moisture (%) Compacted Dry Density (pcf) Final Moisture (%) Volumetric Swell (%) Expansion Index1 Value/Method Expansive Classification2 Soluble Sulfate (%) Sulfate Exposure3 EI-1 Bldg A 0-1' 10.5 107.0 22.9 6.94 69 A Medium -- -- EI-2 Bldg B 0-1' 10.5 108.4 22.2 4.44 44 A Low -- -- Test Method: ASTM D4829 HACH SF-1 (Turbidimetric) Notes: 1. Expansion Index (EI) method of determination: [A] E.I. determined by adjusting water content to achieve a 50 ±2% degree of saturation [B] E.I. calculated based on measured saturation within the range of 40% and 60% 2. ASTM D4829 (Classification of Expansive Soil) 3. ACI-318-14 Table 19.3.1.1 (Requirement for Concrete Exposed to Sulfate-Containing Solutions) Expansion Index and Soluble Sulfate Test Results (FRM001 Rev.5) Project No. 21014-07 Project Name: Arete VP / Marja Acres Commercial NMG ~ Project X REPORT S241009B Corrosion Engineering Page 2 Corrosion Control – Soil, Water, Metallurgy Testing Lab 29990 Technology Dr., Suite 13, Murrieta, CA 92563 Tel: 213-928-7213 Fax: 951-226-1720 www.projectxcorrosion.com Soil Analysis Lab Results Client: NMG Geotechnical Job Name: Arete / Marja Commercial Client Job Number: 21014-07 Project X Job Number: S241009B October 10, 2024 Method ASTM G51 ASTM G200 SM 4500-D ASTM D4327 ASTM D6919 ASTM D6919 ASTM D6919 ASTM D6919 ASTM D6919 ASTM D6919 ASTM D4327 ASTM D4327 Bore# / Description Depth pH Redox Sulfide S2- Nitrate NO3- Ammonium NH4+ Lithium Li+ Sodium Na+ Potassium K+ Magnesium Mg2+ Calcium Ca2+ Fluoride F22- Phosphate PO43- (ft)(mg/kg) (wt%) (mg/kg) (wt%)(Ω-cm) (Ω-cm)(mV) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) Bldg. B (Pad "A") Brn si CL w/sa -1.0 72.6 0.0073 43.6 0.0044 1,206 938 8.9 154 1.3 0.1 4.6 ND 128.4 5.2 27.8 88.4 6.9 0.2 ASTM G187ASTM D4327 ASTM D4327 Resistivity As Rec'd | Minimum Sulfates SO42- Chlorides Cl- Cations and Anions, except Sulfide and Bicarbonate, tested with Ion Chromatography mg/kg = milligrams per kilogram (parts per million) of dry soil weight ND = 0 = Not Detected | NT = Not Tested | Unk = Unknown Chemical Analysis performed on 1:3 Soil-To-Water extract PPM = mg/kg (soil) = mg/L (Liquid) Note: Sometimes a bad sulfate hit is a contaminated spot. Typical fertilizers are Potassium chloride, ammonium sulfate or ammonium sulfate nitrate (ASN). So this is another reason why testing full corrosion series is good because we then have the data to see if those other ingredients are present meaning the soil sample is just fertilizer- contaminated soil. This can happen often when the soil samples collected are simply surface scoops. This is why it's best to dig in a foot, throw away the top and test the deeper stuff. Dairy farms are also notorious for these items. If one sample pops up much more corrosive than all others, we would recommend collecting more samples surrounding the problem sample location to determine if the peak is isolated to it. This allows us to conclude it was a contaminated sample and able to declare it an outlier. Try out our new online forms: SOIL CORROSIVITY & THERMAL RESISTIVITY LAB REQUEST FORM & IN-SITU WENNER 4 PIN QUOTE REQUEST FORM APPENDIX C • Fresh Look Mobile Auto Detailing ? -· -Q) J:>' Google KB Home Coral Parsley Ln Cindy Ave VJ .r:: CJ C: (tJ Q:' ~ OS HPD ~ ~ -~ ~ t' _, Map data ©2024 Google .................................... Pie; •• •• ••• •• •. , .. ••• •• • • ••• .• .• •• ••• •• •• ■ ■ ■ □ □ □ □ □ ■ ■ ■ ■ APPENDIX D O:\NMGDOC\Reports\Appendices\Appendix D - Grading Specifications.doc D-1 APPENDIX D GENERAL EARTHWORK AND GRADING SPECIFICATIONS 1.0 General 1.1 Intent: These General Earthwork and Grading Specifications are for the grading and earthwork shown on the approved grading plan(s) and/or indicated in the geotechnical report(s). These Specifications are a part of the recommendations contained in the geotechnical report(s). In case of conflict, the specific recommendations in the geotechnical report shall supersede these more general Specifications. Observations of the earthwork by the project Geotechnical Consultant during the course of grading may result in new or revised recommendations that could supersede these specifications or the recommendations in the geotechnical report(s). 1.2 Geotechnical Consultant: Prior to commencement of work, the owner shall employ a geotechnical consultant. The geotechnical consultant shall be responsible for reviewing the approved geotechnical report(s) and accepting the adequacy of the preliminary geotechnical findings, conclusions, and recommendations prior to the commencement of the grading. Prior to commencement of grading, the Geotechnical Consultant shall review the "work plan" prepared by the Earthwork Contractor (Contractor) and schedule sufficient personnel to perform the appropriate level of observation, mapping, and compaction testing. During the grading and earthwork operations, the Geotechnical Consultant shall observe, map, and document the subsurface exposures to verify the geotechnical design assumptions. If the observed conditions are found to be significantly different than the interpreted assumptions during the design phase, the Geotechnical Consultant shall inform the owner, recommend appropriate changes in design to accommodate the observed conditions, and notify the review agency where required. Subsurface areas to be geotechnically observed, mapped, elevations recorded, and/or tested include natural ground after it has been cleared for receiving fill but before fill is placed, bottoms of all "remedial removal" areas, all key bottoms, and benches made on sloping ground to receive fill. The Geotechnical Consultant shall observe the moisture-conditioning and processing of the subgrade and fill materials and perform relative compaction testing of fill to determine the attained level of compaction. The Geotechnical Consultant shall provide the test results to the owner and the Contractor on a routine and frequent basis. O:\NMGDOC\Reports\Appendices\Appendix D - Grading Specifications.doc D-2 1.3 The Earthwork Contractor: The Earthwork Contractor (Contractor) shall be qualified, experienced, and knowledgeable in earthwork logistics, preparation and processing of ground to receive fill, moisture-conditioning and processing of fill, and compacting fill. The Contractor shall review and accept the plans, geotechnical report(s), and these Specifications prior to commencement of grading. The Contractor shall be solely responsible for performing the grading in accordance with the plans and specifications. The Contractor shall prepare and submit to the owner and the Geotechnical Consultant a work plan that indicates the sequence of earthwork grading, the number of "spreads" of work and the estimated quantities of daily earthwork contemplated for the site prior to commencement of grading. The Contractor shall inform the owner and the Geotechnical Consultant of changes in work schedules and updates to the work plan at least 24 hours in advance of such changes so that appropriate observations and tests can be planned and accomplished. The Contractor shall not assume that the Geotechnical Consultant is aware of all grading operations. The Contractor shall have the sole responsibility to provide adequate equipment and methods to accomplish the earthwork in accordance with the applicable grading codes and agency ordinances, these Specifications, and the recommendations in the approved geotechnical report(s) and grading plan(s). If, in the opinion of the Geotechnical Consultant, unsatisfactory conditions, such as unsuitable soil, improper moisture condition, inadequate compaction, insufficient buttress key size, adverse weather, etc., are resulting in a quality of work less than required in these specifications, the Geotechnical Consultant shall reject the work and may recommend to the owner that construction be stopped until the conditions are rectified. 2.0 Preparation of Areas to be Filled 2.1 Clearing and Grubbing: Vegetation, such as brush, grass, roots, and other deleterious material shall be sufficiently removed and properly disposed of in a method acceptable to the owner, governing agencies, and the Geotechnical Consultant. The Geotechnical Consultant shall evaluate the extent of these removals depending on specific site conditions. Earth fill material shall not contain more than 1 percent of organic materials (by volume). No fill lift shall contain more than 5 percent of organic matter. Nesting of the organic materials shall not be allowed. If potentially hazardous materials are encountered, the Contractor shall stop work in the affected area, and a hazardous material specialist shall be informed immediately for proper evaluation and handling of these materials prior to continuing to work in that area. O:\NMGDOC\Reports\Appendices\Appendix D - Grading Specifications.doc D-3 As presently defined by the State of California, most refined petroleum products (gasoline, diesel fuel, motor oil, grease, coolant, etc.) have chemical constituents that are considered to be hazardous waste. As such, the indiscriminate dumping or spillage of these fluids onto the ground may constitute a misdemeanor, punishable by fines and/or imprisonment, and shall not be allowed. 2.2 Processing: Existing ground that has been declared satisfactory for support of fill by the Geotechnical Consultant shall be scarified to a minimum depth of 6 inches. Existing ground that is not satisfactory shall be overexcavated as specified in the following section. Scarification shall continue until soils are broken down and free of large clay lumps or clods and the working surface is reasonably uniform, flat, and free of uneven features that would inhibit uniform compaction. 2.3 Overexcavation: In addition to removals and overexcavations recommended in the approved geotechnical report(s) and the grading plan, soft, loose, dry, saturated, spongy, organic-rich, highly fractured or otherwise unsuitable ground shall be overexcavated to competent ground as evaluated by the Geotechnical Consultant during grading. 2.4 Benching: Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical units), the ground shall be stepped or benched. Please see the Standard Details for a graphic illustration. The lowest bench or key shall be a minimum of 15 feet wide and at least 2 feet deep, into competent material as evaluated by the Geotechnical Consultant. Other benches shall be excavated a minimum height of 4 feet into competent material or as otherwise recommended by the Geotechnical Consultant. Fill placed on ground sloping flatter than 5:1 shall also be benched or otherwise overexcavated to provide a flat subgrade for the fill. 2.5 Evaluation/Acceptance of Fill Areas: All areas to receive fill, including removal and processed areas, key bottoms, and benches, shall be observed, mapped, elevations recorded, and/or tested prior to being accepted by the Geotechnical Consultant as suitable to receive fill. The Contractor shall obtain a written acceptance from the Geotechnical Consultant prior to fill placement. A licensed surveyor shall provide the survey control for determining elevations of processed areas, keys, and benches. O:\NMGDOC\Reports\Appendices\Appendix D - Grading Specifications.doc D-4 3.0 Fill Material 3.1 General: Material to be used as fill shall be essentially free of organic matter and other deleterious substances evaluated and accepted by the Geotechnical Consultant prior to placement. Soils of poor quality, such as those with unacceptable gradation, high expansion potential, or low strength shall be placed in areas acceptable to the Geotechnical Consultant or mixed with other soils to achieve satisfactory fill material. 3.2 Oversize: Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 12 inches, shall not be buried or placed in fill unless location, materials, and placement methods are specifically accepted by the Geotechnical Consultant. Placement operations shall be such that nesting of oversized material does not occur and such that oversize material is completely surrounded by compacted or densified fill. Oversize material shall not be placed within 10 vertical feet of finish grade or within 2 feet of future utilities or underground construction. 3.3 Import: If importing of fill material is required for grading, proposed import material shall meet the requirements of Section 3.1. The potential import source shall be given to the Geotechnical Consultant at least 48 hours (2 working days) before importing begins so that its suitability can be determined and appropriate tests performed. 4.0 Fill Placement and Compaction 4.1 Fill Layers: Approved fill material shall be placed in areas prepared to receive fill (per Section 3.0) in near-horizontal layers not exceeding 8 inches in loose thickness. The Geotechnical Consultant may accept thicker layers if testing indicates the grading procedures can adequately compact the thicker layers. Each layer shall be spread evenly and mixed thoroughly to attain relative uniformity of material and moisture throughout. 4.2 Fill Moisture Conditioning: Fill soils shall be watered, dried back, blended, and/or mixed, as necessary to attain a relatively uniform moisture content at or slightly over optimum. Maximum density and optimum soil moisture content tests shall be performed in accordance with the American Society of Testing and Materials (ASTM Test Method D1557-91). 4.3 Compaction of Fill: After each layer has been moisture-conditioned, mixed, and evenly spread, it shall be uniformly compacted to not less than 90 percent of maximum dry density (ASTM Test Method D1557-91). Compaction equipment shall be adequately sized and be either specifically designed for soil compaction or of proven reliability to efficiently achieve the specified level of compaction with uniformity. O:\NMGDOC\Reports\Appendices\Appendix D - Grading Specifications.doc D-5 4.4 Compaction of Fill Slopes: In addition to normal compaction procedures specified above, compaction of slopes shall be accomplished by backrolling of slopes with sheepsfoot rollers at increments of 3 to 4 feet in fill elevation, or by other methods producing satisfactory results acceptable to the Geotechnical Consultant. Upon completion of grading, relative compaction of the fill, out to the slope face, shall be at least 90 percent of maximum density per ASTM Test Method D1557-91. 4.5 Compaction Testing: Field tests for moisture content and relative compaction of the fill soils shall be performed by the Geotechnical Consultant. Location and frequency of tests shall be at the Consultant’s discretion based on field conditions encountered. Compaction test locations will not necessarily be selected on a random basis. Test locations shall be selected to verify adequacy of compaction levels in areas that are judged to be prone to inadequate compaction (such as close to slope faces and at the fill/bedrock benches). 4.6 Frequency of Compaction Testing: Tests shall be taken at intervals not exceeding 2 feet in vertical rise and/or 1,000 cubic yards of compacted fill soils embankment. In addition, as a guideline, at least one test shall be taken on slope faces for each 5,000 square feet of slope face and/or each 10 feet of vertical height of slope. The Contractor shall assure that fill construction is such that the testing schedule can be accomplished by the Geotechnical Consultant. The Contractor shall stop or slow down the earthwork construction if these minimum standards are not met. 4.7 Compaction Test Locations: The Geotechnical Consultant shall document the approximate elevation and horizontal coordinates of each test location. The Contractor shall coordinate with the project surveyor to assure that sufficient grade stakes are established so that the Geotechnical Consultant can determine the test locations with sufficient accuracy. At a minimum, two grade stakes within a horizontal distance of 100 feet and vertically less than 5 feet apart from potential test locations shall be provided. 5.0 Subdrain Installation Subdrain systems shall be installed in accordance with the approved geotechnical report(s), the grading plan, and the Standard Details. The Geotechnical Consultant may recommend additional subdrains and/or changes in subdrain extent, location, grade, or material depending on conditions encountered during grading. All subdrains shall be surveyed by a land surveyor/civil engineer for line and grade after installation and prior to burial. Sufficient time should be allowed by the Contractor for these surveys. O:\NMGDOC\Reports\Appendices\Appendix D - Grading Specifications.doc D-6 6.0 Excavation Excavations, as well as over-excavation for remedial purposes, shall be evaluated by the Geotechnical Consultant during grading. Remedial removal depths shown on geotechnical plans are estimates only. The actual extent of removal shall be determined by the Geotechnical Consultant based on the field evaluation of exposed conditions during grading. Where fill-over-cut slopes are to be graded, the cut portion of the slope shall be made, evaluated, and accepted by the Geotechnical Consultant prior to placement of materials for construction of the fill portion of the slope, unless otherwise recommended by the Geotechnical Consultant. 7.0 Trench Backfills 7.1 Contractor shall follow all OHSA and Cal/OSHA requirements for safety of trench excavations. 7.2 Bedding and backfill of utility trenches shall be done in accordance with the applicable provisions of Standard Specifications of Public Works Construction. Bedding material shall have a Sand Equivalent greater than 30 (SE>30). The bedding shall be placed to 1 foot over the top of the conduit and densified by jetting. Backfill shall be placed and densified to a minimum 90 percent of maximum from 1 foot above the top of the conduit to the surface, except in traveled ways (see Section 7.6 below). 7.3 Jetting of the bedding around the conduits shall be observed by the Geotechnical Consultant. 7.4 Geotechnical Consultant shall test the trench backfill for relative compaction. At least one test should be made for every 300 feet of trench and 2 feet of fill. 7.5 Lift thickness of trench backfill shall not exceed those allowed in the Standard Specifications of Public Works Construction unless the Contractor can demonstrate to the Geotechnical Consultant that the fill lift can be compacted to the minimum relative compaction by his alternative equipment and method. 7.6 Trench backfill in the upper foot measured from finish grade/subgrade within existing or future traveled way, shoulder, and other paved areas (or areas to receive pavement) should be placed to a minimum 95 percent relative compaction unless specified differently by the governing agency. 17991 Fitch • Irvine, California 92614 • PHONE (949) 442-2442 • FAX (949) 476-8322 • www.nmggeotechnical.com April 7, 2025 Project No. 21014-07 To: Arete VP, LLC. 5973 Avenida Encinas, Suite 305 Carlsbad, California 92008 Attention: Mr. Jeff Edinger Subject: Geotechnical Review of Precise Grade Plan for Commercial Site within the Marja Acres Mixed-Use Development, 4901 El Camino Real, City of Carlsbad, California Reference: NMG Geotechnical Inc., 2024, Geotechnical Design Report for Commercial Site within the Marja Acres Mixed-Use Development, 4901 El Camino Real, City of Carlsbad, California, Project No. 21014-07, dated October 28, 2024. Per your request, NMG Geotechnical, Inc. (NMG) has performed a geotechnical review of the precise grade plan for the proposed Commercial Site at Marja Acres. We reviewed the 10-scale plan titled, "Precise Grading Plan, Marja Acres." The plan was prepared by Fuscoe, received by NMG on April 1, 2025. This report includes a summary of our review and presents our conclusion. The precise grading plans consists of Sheets 1, 3, and 6 through 8 of 50 total sheets. Sheet 1 is the title sheet and contains a vicinity map, earthwork quantities, grading, and sheet index. Sheet 3 contains details. Sheets 6 through 8 are the 10-scale precise grading plans. Precise grading within the production portion of the site should consist of relatively minor cuts and fills, generally less than 1 foot thick. The production precise grading plan provides the following information: • Commercial Buildings A and B footprints (with finish pad grades, finish floor); • Locations of pedestrian pavers; • Location of decorative pavement (previously reviewed in prior delta revisions); • Location of 4-inch asphaltic concrete over 12 inches for the parking lot pavement and stalls; • Location of 6-inch concrete Trash Enclosure slab over 4 inches aggregate base; • Location of freestanding walls, sidewalks, flatwork, and driveways; • Locations of CMU retaining walls (per separate permit); • Locations of Biofiltration Basins (per separate permit); and • Lot surface drainage to be carried toward the street or storm-drain facilities by various combinations of sheet flow, swales, and area-drain pipes. APPENDIX "E" 21014-07 April 7, 2025 250407 Commercial PGP Report 2 NMG Based on our review of the subject plan and review of the referenced report (NMG, 2024), the proposed precise grading and construction, as described herein, is considered acceptable from a geotechnical viewpoint. The recommendations presented in this report and the referenced report should be implemented in design, grading, and construction of improvements. If you have any questions regarding this report, please contact our office. We appreciate the opportunity to provide our services. Respectfully submitted, NMG GEOTECHNICAL, INC. Trent Casillas, RCE 88829 Project Engineer TM/TAC/je Email Distribution: Addressee Mr. Jaemin Blackwelder, Fuscoe Mr. Alex Stone, Edinger Architects 17991 Fitch • Irvine, California 92614 • PHONE (949) 442-2442 • FAX (949) 476-8322 • www.nmggeotechnical.com September 30, 2025 Project No. 21014-07 To: Arete VP, LLC. 5973 Avenida Encinas, Suite 305 Carlsbad, California 92008 Attention: Mr. Jeff Edinger Subject: Geotechnical Review of Updated Precise Grade Plan for Commercial Site within the Marja Acres Mixed-Use Development, 4901 El Camino Real, City of Carlsbad, California References: NMG Geotechnical Inc., 2025, Geotechnical Review of Precise Grade Plan for Commercial Site within the Marja Acres Mixed-Use Development, 4901 El Camino Real, City of Carlsbad, California, Project No. 21014-07, dated April 7, 2025. NMG Geotechnical Inc., 2024, Geotechnical Design Report for Commercial Site within the Marja Acres Mixed-Use Development, 4901 El Camino Real, City of Carlsbad, California, Project No. 21014-07, dated October 28, 2024. Per your request, NMG Geotechnical, Inc. (NMG) has performed a geotechnical review of the updated precise grade plan for the proposed Commercial Site at Marja Acres. We reviewed the 10-scale plan titled, "Precise Grading Plan, Marja Acres." The updated plan was prepared by Fuscoe, received by NMG on September 30, 2025. This supersedes our previous review of the commercial site grading plan (NMG, 2025). The revisions only consisted of re-sheeting and making the plans stand alone. No changes were made to the grading design. This report includes a summary of our review and presents our conclusion. The precise grading plan consists of Sheets 1 through 5 of 5 total sheets. Sheet 1 is the title sheet and contains a vicinity map, earthwork quantities, grading, and sheet index. Sheets 2 through 4 are the 10-scale precise grading plans. Sheet 5 is the utility plan. Precise grading within the production portion of the site should consist of relatively minor cuts and fills, generally less than 1 foot thick. The production precise grading plan provides the following information: • Commercial Buildings A and B footprints (with finish pad grades, finish floor), • Locations of pedestrian pavers, • Location of decorative pavement (previously reviewed in prior delta revisions), • Location of 4-inch asphaltic concrete over 12 inches for the parking lot pavement and stalls, APPENDIX "F" 21014-07 September 30, 2025 250930 Commercial PGP Report 2 NMG • Location of 6-inch concrete trash enclosure slab over 4 inches of aggregate base, • Location of freestanding walls, sidewalks, flatwork, and driveways, • Locations of CMU retaining walls (per separate permit), • Locations of Biofiltration Basins (per separate permit), and • Lot surface drainage to be carried toward the street or storm-drain facilities by various combinations of sheet flow, swales, and area-drain pipes. Based on our review of the subject plan and review of the referenced report (NMG, 2024), the proposed precise grading and construction, as described herein, is considered acceptable from a geotechnical viewpoint. The recommendations presented in this report and the referenced report should be implemented in design, grading, and construction of improvements. If you have any questions regarding this report, please contact our office. We appreciate the opportunity to provide our services. Respectfully submitted, NMG GEOTECHNICAL, INC. Trent Casillas, RCE 88829 Project Engineer TM/TAC/je E-Mail Distribution: Addressee Mr. Jaemin Blackwelder, Fuscoe Mr. Alex Stone, Edinger Architects