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Home My WebLink AboutSDP 2021-0016; CARLSBAD OAKS NORTH LOT 3; UPDATE GEOTECHNICAL REPORT; 2021-05-26UPDATE GEOTECHNICAL REPORT CARLSBAD OAKS NORTH BUSINESS PARK – LOT 3 CARLSBAD, CALIFORNIA PREPARED FOR TECH CONTRACTORS SAN DIEGO, CALIFORNIA MAY 26, 2021 PROJECT NO. 06442-32-34 TABLE OF CONTENTS 1. PURPOSE AND SCOPE ...................................................................................................................... 1 2. PREVIOUS SITE DEVELOPMENT ................................................................................................... 1 3. SITE AND PROJECT DESCRIPTION ................................................................................................ 1 4. SOIL AND GEOLOGIC CONDITIONS ............................................................................................. 24.1 Compacted Fill (Qcf) .................................................................................................................. 24.2 Granitic Rock (Kgr) .................................................................................................................... 3 5. RIPPABILITY AND ROCK CONSIDERATIONS ............................................................................. 3 6. GROUNDWATER ............................................................................................................................... 4 7. GEOLOGIC HAZARDS ...................................................................................................................... 47.1 Ground Rupture .......................................................................................................................... 47.2 Seismicity ................................................................................................................................... 47.3 Subsidence .................................................................................................................................. 57.4 Tsunamis and Seiches ................................................................................................................. 57.5 Flooding ...................................................................................................................................... 57.6 Liquefaction and Seismically Induced Settlement ...................................................................... 57.7 Landslides ................................................................................................................................... 5 8. CONCLUSIONS AND RECOMMENDATIONS ................................................................................ 68.1 General ........................................................................................................................................ 68.2 Excavation and Soil Characteristics ........................................................................................... 68.3 Grading Recommendations ........................................................................................................ 88.4 Subdrains .................................................................................................................................. 108.5 Slopes ........................................................................................................................................ 108.6 Seismic Design Criteria ............................................................................................................ 108.7 Shallow Foundations ................................................................................................................ 128.8 Interior Concrete Slabs-on-Grade ............................................................................................. 148.9 Conventional Retaining Wall Recommendations ..................................................................... 158.10 Lateral Loading ......................................................................................................................... 198.11 Preliminary Pavement Recommendations – Flexible and Rigid .............................................. 198.12 Exterior Concrete Flatwork ...................................................................................................... 238.13 Storm Water Management (Detention Basin and Bioswales) .................................................. 248.14 Site Drainage and Moisture Protection ..................................................................................... 258.15 Slope Maintenance.................................................................................................................... 268.16 Grading, Foundation and Retaining Wall Plan Review ............................................................ 26 MAPS AND ILLUSTRATIONS Figure 1, Vicinity Map Figure 2, Geologic Map Figure 3, Geologic Cross-Sections A-A’ through C-C’ APPENDIX A RIPPABILITY STUDY Figures A-1  A-9, Logs of Exploratory Trench Excavations APPENDIX B LABORATORY TESTING (Geocon Incorporated, 2007) APPENDIX C City of Carlsbad BMP Design Manual – Categorization of Infiltration Feasibility Condition (Form I-8) APPENDIX D RECOMMENDED GRADING SPECIFICATIONS LIST OF REFERENCES Geocon Project No. 06442-32-34 - 1 - May 26, 2021 UPDATE GEOTECHNICAL INVESTIGATION 1. PURPOSE AND SCOPE This report presents the results of an update geotechnical study for the proposed Carlsbad Oaks North Business Park – Lot 3 development located in the Carlsbad Oaks North Business Park in Carlsbad, California (see Vicinity Map, Figure 1). The purpose of this report was to evaluate the soil and geologic conditions within the site and provide geotechnical recommendations pertaining to the development of the property as proposed. The scope of this update report included a review of: 1.Final Report of Testing and Observation Services During Site Grading, Carlsbad Oaks North Business Park – Phase 1, (Lots 1 through 9), Carlsbad, California, prepared by Geocon Incorporated, dated August 30, 2006 (Geocon Project No. 06442-32-04A). 2.Update Geotechnical Investigation, Carlsbad Oaks North Business Park and Faraday Avenue Offsite, Carlsbad, California, prepared by Geocon Incorporated, dated October 21, 2004 (Geocon Project No. 06442-32-03). 3.Conceptual Grading Plan for: Carlsbad Oaks North - Lot 3, Carlsbad, California, prepared by Spear & Associates, undated. The descriptions of the soil and geologic conditions and proposed development described herein is based on review of the referenced reports and plan, and observations made during previous mass grading operations for the overall Carlsbad Oaks North Business Park development. Additional references reviewed to prepare this report are provided in the List of References. 2. PREVIOUS SITE DEVELOPMENT We provided testing and observation services during mass grading of the property. A canyon subdrain was placed during the grading across the lot and extends beyond the property boundary. Our professional opinions pertaining to the grading are summarized in Reference No. 1 (report dated August 30, 2006). Appendix A presents pertinent laboratory tests that we performed on selected soil samples collected during previous grading. 3. SITE AND PROJECT DESCRIPTION The lot is bounded by Whiptail Loop to the east, open space to the west and south, and Pacifica Vista Commerce Center (formerly Lot 23) to the north. The property mostly consists of compacted fill at existing grade. Granitic rock is located along the northeast portion of the lot. Ascending and descending 2:1 (horizontal:vertical) fill and cut slopes are located along the perimeter of the lot with a maximum Geocon Project No. 06442-32-34 - 2 - May 26, 2021 height of approximately 50 feet. Sparse low lying grass/weeds are spread across the property. A temporary paved drive isle and sales trailer is located along south margin of the sheet-graded pad. The sheet-graded pad portion of the lot slopes from the northwest to southeast with elevations varying from approximately 328 feet above Mean Sea Level (MSL) to approximately 316 feet MSL. A temporary detention basin is located in the southeast margin of the pad. Existing improvements within the lot consist of a storm drain system that was constructed as part of the temporary detention basin. The slopes are landscaped with shrubs and trees with an active irrigation system. We understand that the proposed development includes grading the existing sheet-graded pad to support three, single-story buildings. We anticipate that the buildings will consist of concrete tilt-up construction supported by convetional continuous and isolated spread footings with slab-on-grade construction. Additional improvements consist of underground utilities, surface parking/driveways, hardscape and bio-retention systems for storm water. The descriptions contained herein are based upon the observations made during mass grading operations and, a review of the referenced reports and plan. If project details vary significantly from those outlined herein, Geocon Incorporated should be notified for review and possible revisions to this report. 4. SOIL AND GEOLOGIC CONDITIONS Compacted fill and granitic bedrock are exposed at finish grade. The approximate lateral extent of the geologic units is presented on the Geologic Map, Figure 2. The subsurface relationship between the soil and geologic unit is presented on the Geologic Cross-Sections A-A′ through C-C′, Figure 3. 4.1 Compacted Fill (Qcf) Compacted fill was placed across the lot during previous grading operations. The fill generally consists of a 3-foot-thick cap of soil containing some 6-inch-minus rock. Fill below the soil cap contains rock fragments up to 12 inches in size. Rocks larger than 12 inches in length and, generally between 2 to 4 feet in maximum dimension, were placed at least 10 feet below finish sheet grade. In some instances, larger boulders were individually placed in the deeper fill areas. The outer approximately 15 feet of embankment slopes consist of soil fill with 6-inch-minus rock and occasional 12-inch material. Although particular attention was given to restricting oversize rock placement as discussed herein, it is possible that some oversize rock (> 12 inches) may be present in the upper portions of fill areas. The presence of oversize rock should be considered during grading and where below-grade improvements (i.e., sewer, storm drain) are proposed in areas deeper than 3 feet below existing sheet grade. Geocon Project No. 06442-32-34 - 3 - May 26, 2021 Fill materials placed during the mass grading operations generally consist of silty sands, and mixtures of angular gravel and boulders generated from excavations in granitic rock. Soils consisting of sandy clays were placed in deeper fill areas. Based on information presented in Reference No. 1, the fill is compacted to at least 90 percent of the laboratory maximum dry density at or slightly above the optimum moisture content in accordance with ASTM D 1557. Excluding the upper approximately one foot, the compacted fill is suitable for support of additional fill and/or structural loading. In areas of planned improvements, the upper one foot of existing fill will require processing as part of further development. 4.2 Granitic Rock (Kgr) Cretaceous-age, granitic basement rock of the Southern California Batholith underlies the compacted fill and is exposed at grade along the northeast portion of the lot. Based upon our observations during mass grading, the rock materials are highly to slightly weathered. Proposed excavations in this unit may encounter hard rock that will result in excavation difficulty and/or possible blasting to excavate. The granitic rock exhibits adequate bearing and slope stability characteristics. The soils derived from excavations within the decomposed granitic rock are expected to consist of very low to low expansive (Expansion Index [EI] < 50), silty, medium- to coarse-grained sands. Excavations within the bedrock will generate boulders and oversize materials (rocks >12 inches) that will require special handling and placement. Oversize rock fragments may also require exportation from the site since the available fill volume is limited. 5. RIPPABILITY AND ROCK CONSIDERATIONS Rock rippability is a function of natural weathering processes that can vary vertically and horizontally over short distances depending on jointing, fracturing, and/or mineralogic discontinuities within the bedrock. We performed a field study to obtain further information regarding rock rippability in areas of planned excavation where granitic rock is exposed at grade. We performed the field investigation on October 28 and November 3, 2020. The study consisted of excavating nine backhoe trenches utilizing a C345BL trackhoe equipped with a 2-foot-wide bucket. The exploratory trench logs are presented in Appendix A, Figures A-1 through A-9. The approximate locations of the exploratory trenches are shown on Figure 2 (map pocket). We used the information obtained from the field study to base an opinion regarding the rippability characteristics of the bedrock. Based on the exploratory trenching performed, it is expected that excavations in the bedrock will encounter rippable granitic rock to at least the depths shown on the trench logs utilizing conventional heavy-duty grading and trenching equipment. We encountered moderately to slightly weathered Geocon Project No. 06442-32-34 - 4 - May 26, 2021 granitic rock resulting in refusal and trenching difficulty (see Appendix A, Figures A-1, A-2 and A-9). In some instances, random core stones up to 5 feet in length were encountered in the trench excavations resulting in excavation difficulties. Where this occurred, the trench excavation was moved beyond the core stone and trenching in the bedrock continued (see Appendix A, Figures A-4 and A-5). Excavations that extend greater than the depths shown on the trench logs may encounter difficult ripping conditions or refusal and require blasting techniques. Excavations can also be expected to generate oversized rock (rocks >12 inches), which will necessitate typical rock handling and/or exportation from the site. Proposed cuts in the weathered (rippable) mantle may also generate oversized fragments. Earthwork construction should be carefully planned to efficiently utilize available rock placement areas, if present. Oversize materials should be placed in accordance with the previously discussed criteria and rock placement procedures presented in Appendix D of this report and governing jurisdictions. 6. GROUNDWATER We did not encounter groundwater or seepage during our recent field study or previous grading operations. However, it is not uncommon for shallow seepage conditions to develop where none previously existed when sites are irrigated or infiltration is implemented. Seepage is dependent on seasonal precipitation, irrigation, land use, among other factors, and varies as a result. Proper surface drainage will be important to future performance of the project. In the event that surface seeps develop, shallow subdrains may be necessary to collect and convey the seepage to a suitable outlet facility. 7. GEOLOGIC HAZARDS 7.1 Ground Rupture The USGS (2020) and Kennedy & Tan (2005) show that there are no mapped Quaternary faults crossing or trending toward the property. The site is not located within a currently established Alquist- Priolo Earthquake Fault Zone. No active faults are known to exist at the site. An active fault is defined by the California Geological Survey (CGS) as a fault showing evidence for activity within the last 11,700 years. The closest active fault is Newport Inglewood-Rose Canyon Fault zone, located approximately 8 miles west of the site. The risk associated with ground rupture hazard is low. 7.2 Seismicity Considerations important in seismic design include the frequency and duration of motion and the soil conditions underlying the site. Seismic design of structures should be evaluated in accordance with the California Building Code (CBC) guidelines currently adopted by the local agency. The risk associated Geocon Project No. 06442-32-34 - 5 - May 26, 2021 with strong ground motion due to earthquake at the site is high; however, the risk is no greater than that for the region. 7.3 Subsidence Based on the subsurface conditions encountered during our field investigation, the risk associated with ground subsidence hazard is low. 7.4 Tsunamis and Seiches The site is not located within a tsunami inundation zone as defined by California Geological Survey (2009). There are no lakes or reservoirs located near the site. The risk associated with inundation hazard due to tsunami or seiche is very low. 7.5 Flooding The site is not located within a drainage or floodplain and is designated a Zone X (FEMA, 2012). The risk associated with flooding hazard is very low. 7.6 Liquefaction and Seismically Induced Settlement The risk associated with liquefaction and seismically induced settlement hazard at the subject project is very low due to the existing dense compacted fill and very dense nature of the granitic bedrock, construction of canyon subdrains, and the lack of a permanent, shallow groundwater table. 7.7 Landslides No landslides were encountered within the site or mapped within the immediate areas influencing the project development. The risk associated with landslide hazard is very low. Geocon Project No. 06442-32-34 - 6 - May 26, 2021 8. CONCLUSIONS AND RECOMMENDATIONS 8.1 General 8.1.1 We did not encounter soil or geologic conditions during this study that would preclude the proposed development, provided the recommendations presented herein are followed and implemented during design and construction. We will provide supplemental recommendations if the proposed construction will differ from that anticipated herein. 8.1.2 Planned grading will result in a cut-fill transition condition across the footprint of proposed Buildings B and C. The cut portion (bedrock) should be undercut and replaced with properly compacted fill to facilitate excavation of the foundation systems and reduce the potential for differential settlement of structures bearing on both cut and fill. 8.1.3 Depending on the time of year that grading is performed, wet to saturated soil conditions may be encountered, especially in the temporary detention basin. Wet soils, if encountered, will need to be dried or mixed with dryer soil to facilitate proper compaction. 8.1.4 It is not uncommon for groundwater or seepage conditions to develop where none previously existed, particularly after landscape irrigation is initiated or following precipitation. The occurrence of induced groundwater seepage from landscaping can be greatly reduced by implementing and monitoring a landscape program that limits irrigation to that sufficient to support the vegetative cover without over watering. Shallow subdrains may be required in the future if seeps occur after rainy periods or after landscaping is installed. 8.1.5 Subsurface conditions observed may be extrapolated to reflect general soil/geologic conditions; however, some variations in subsurface conditions between trench locations should be anticipated. 8.2 Excavation and Soil Characteristics 8.2.1 Excavation of existing compacted fill should be possible with light to moderate effort using conventional heavy-duty grading and trenching equipment. Excavations for improvements in fill areas that extend through the 6-inch-minus soil cap or into the granitic rock will encounter hard rock and/or rock fragments greater than 12 inches. Excavation difficulties should be anticipated for these conditions. Blasting or rock breaking may be required for excavations that are planned in granitic rock areas. Core stones or oversize material may also be generated that will require special handling and fill placement procedures. The potential for these conditions should be taken into consideration when determining the type Geocon Project No. 06442-32-34 - 7 - May 26, 2021 of equipment to utilize for future excavation operations. Due to the limited areas of available fill volume, it is unlikely that the oversize material could be placed as compacted fill during the grading operation; hence, the oversize material may need to be exported or crushed to an appropriate size for fill placement. 8.2.2 Laboratory testing performed on soil samples collected during mass grading operations indicate that the prevailing soils within approximately 3 feet of grade have an Expansion Index (EI) less than 20 and are defined as “non-expansive” as defined by 2019 California Building Code (CBC) Section 1803.5.3. Appendix B presents the laboratory expansion potential test results. Table 8.2 presents soil classifications based on the expansion index. We expect the majority of the on-site soils possess a very low expansion potential. We will perform additional expansion index testing after completion of grading operations to evaluate the expansion potential of material present within the upper approximately 3 feet of ultimate design finish elevation. TABLE 8.2 EXPANSION CLASSIFICATION BASED ON EXPANSION INDEX Expansion Index (EI) ASTM D 4829 Expansion Classification 2019 CBC Expansion Classification 0 – 20 Very Low Non-Expansive 21 – 50 Low Expansive 51 – 90 Medium 91 – 130 High Greater Than 130 Very High 8.2.3 We performed laboratory tests on samples collected during previous grading to evaluate the percentage of water-soluble sulfate content. Appendix B presents results of the laboratory water-soluble sulfate content tests. The test results indicate the on-site materials at the locations tested possess “S0” sulfate exposure to concrete structures as defined by 2019 CBC Section 1904 and ACI 318-14 Chapter 19. The presence of water-soluble sulfates is not a visually discernible characteristic; therefore, other soil samples from the site could yield different concentrations. Additionally, over time landscaping activities (i.e., addition of fertilizers and other soil nutrients) may affect the concentration. We will perform additional water-soluble sulfate testing after completion of grading operations to evaluate the sulfate exposure of material present within the upper approximately three feet of ultimate design finish elevation. Geocon Project No. 06442-32-34 - 8 - May 26, 2021 8.2.4 Geocon Incorporated does not practice in the field of corrosion engineering. Therefore, further evaluation by a corrosion engineer may be performed if improvements susceptible to corrosion are planned. 8.3 Grading Recommendations 8.3.1 Grading should be performed in accordance with the Recommended Grading Specifications contained in Appendix D. Where the recommendations of Appendix D conflict with this section of the report, the recommendations of this section take precedence. 8.3.2 Prior to commencing grading, a preconstruction conference should be held at the site with the City inspector, developer, grading contractor, civil engineer, and geotechnical engineer in attendance. Special soil handling and/or the grading plans can be discussed at that time. 8.3.3 Grading should be performed in conjunction with the observation and compaction testing services of Geocon Incorporated. Fill soil should be observed on a full-time basis during placement and tested to check in-place dry density and moisture content. 8.3.4 Site preparation should begin with removal of all deleterious material, vegetation and, abandoned utilities/improvements. Loose accumulated soils in the temporary detention basin will need to be removed and compacted prior to filling the basin. The depth of removal should be such that material exposed in cut areas or soil to be used for fill is relatively free of organic matter. Deleterious material generated during stripping and/or site demolition should be exported from the site. 8.3.5 Prior to placing fill, the exposed ground surface should be scarified approximately 12 inches, moisture conditioned as necessary, mixed and compacted to 90 percent of the laboratory maximum dry density as determined by ASTM D1557 at or slightly above optimum moisture content. Overly wet surficial soils, if encountered, will need to be removed to expose existing dense, moist compacted fill (where mapped) or granitic rock. The wet soils will require drying and/or mixing with drier soils to facilitate proper compaction. The actual extent of remedial grading should be determined in the field by the geotechnical engineer or engineering geologist. 8.3.6 After site preparation and removal of unsuitable soils, as described above is performed, the site should be brought to final subgrade elevation with structural fill. In general, on-site soils are suitable for re-use as fill provided they are free of vegetation, debris and other deleterious matter. Layers of fill should be no thicker than will allow for adequate bonding and compaction. Fill, including backfill and scarified ground surfaces, should be compacted to at Geocon Project No. 06442-32-34 - 9 - May 26, 2021 least 90 percent of the laboratory maximum dry density as determined by ASTM D 1557, at or slightly above optimum moisture content. The project geotechnical engineer may consider fill materials below the recommended minimum moisture content unacceptable and may require additional moisture conditioning prior to placing additional fill. 8.3.7 Based on existing as-graded condition of the pad portion of the lot and proposed grading presented on the conceptual grading plan, grading will result in a cut-fill transition condition within the footprint of planned Buildings B and C. Foundation elements bearing on both compacted fill and bedrock may result in potentially unacceptable differential settlements. 8.3.8 To reduce the potential for differential settlement, the bedrock portion of the cut-fill transition should be over-excavated (undercut) a minimum of 5 feet below finish pad grade or at least 2 feet below the lowest foundation element, whichever is deeper, and replaced with compacted low expansive (Expansion Index [EI] <50) soil fill consisting of 6-inch-minus rock. The undercutting will also facilitate excavation of proposed shallow utilities beneath the building. The undercut should extend at least 5 feet horizontally outside the limits of the building footprint area and isolated spread footings located outside the building limits. Overexcavations should be cut at a gradient toward the parking lot or toward the deepest fill area to provide drainage for moisture migration along the contact between the bedrock and compacted fill. 8.3.9 For exterior utilities (i.e., storm drain, sewer, dry utilities, water) that may be located in areas of granitic rock, consideration should be given to undercutting the granitic rock to facilitate trenching for planned underground utilities. The need to undercut the underlying granitic rock within the utility corridors should be determined by the owner based on the rippability study included herein (see Section 5 for discussion). The undercuts, if needed, should extend at least 1 foot below the deepest utility. 8.3.10 Consideration should be given to undercutting landscape areas, hardscape zones and driveways/parking areas located in areas of exposed granitic rock to facilitate construction of planned improvements. The need to undercut the underlying granitic rock within these zones should be determined by the owner based on the findings of the exploratory trenching performed. 8.3.11 In order to maintain safety and the stability of adjacent improvements, it is the responsibility of the contractor to ensure that all excavations and trenches are properly shored and maintained in accordance with the applicable OSHA rules and regulations. 8.3.12 Imported soils should consist of granular very low to low expansive soils (EI <50). Samples from proposed borrow areas should be obtained and subjected to laboratory testing to Geocon Project No. 06442-32-34 - 10 - May 26, 2021 evaluate if the material conforms to the recommended criteria prior to importing to the site. The imported soil should be free of rock greater than 6 inches and construction debris. Laboratory testing typically takes up to four days to complete. The grading contractor needs to coordinate the laboratory testing into the schedule to provide sufficient time to allow for completion of testing prior to importing materials. 8.4 Subdrains 8.4.1 Except for retaining wall drains, subdrains are not required for the project. 8.5 Slopes 8.5.1 Slope stability analyses were previously performed on the 2:1 slopes for the overall Carlsbad Oaks North Business Park development (see the referenced geotechnical reports). The deep-seated and surficial slope stability analyses where performed using the simplified Janbu analysis utilizing average drained direct shear strength parameters based on laboratory tests performed during our investigation. The results of the analysis indicate that existing cut and fill slopes have a factor-of-safety of at least 1.5 against deep seated and surficial instability for the project slopes. 8.5.2 No new significant slopes are planned for the project. We expect that interior fill slopes with inclinations of 2:1 (horizontal:vertical) or flatter and maximum heights of approximately 3 feet will be constructed during grading operations. Based on the discussion above, these slopes should have a factor-of-safety of at least 1.5 against deep seated and surficial instability. 8.5.3 Slopes should be landscaped with drought-tolerant vegetation having variable root depths and requiring minimal landscape irrigation. In addition, all slopes should be drained and properly maintained to reduce erosion. Slope planting should generally consist of drought tolerant plants having a variable root depth. Slope watering should be kept to a minimum to just support the plant growth. 8.6 Seismic Design Criteria 8.6.1 Table 8.6.1 summarizes site-specific design criteria obtained from the 2019 California Building Code (CBC; Based on the 2018 International Building Code [IBC] and NEHRP- 2015), Chapter 16 Structural Design, Section 1613 Earthquake Loads. We used the computer program U.S. Seismic Design Maps, provided by the Structural Engineers Association of California (SEAOC) to calculate the seismic design parameters. The short spectral response uses a period of 0.2 second. We evaluated the Site Class based on the Geocon Project No. 06442-32-34 - 11 - May 26, 2021 discussion in Section 1613.2.2 of the 2019 CBC and Table 20.3-1 of ASCE 7-16. The values presented herein are for the risk-targeted maximum considered earthquake (MCER). TABLE 8.6.1 2019 CBC SEISMIC DESIGN PARAMETERS Parameter Value 2019 CBC Reference Site Class D Section 1613.2.2 MCER Ground Motion Spectral Response Acceleration – Class B (short), SS 0.932g Figure 1613.2.1(1) MCER Ground Motion Spectral Response Acceleration – Class B (1 sec), S1 0.342g Figure 1613.2.1(2) Site Coefficient, FA 1.127 Table 1613.2.3(1) Site Coefficient, FV 1.958* Table 1613.2.3(2) Site Class Modified MCER Spectral Response Acceleration (short), SMS 1.051g Section 1613.2.3 (Eqn 16-36) Site Class Modified MCER Spectral Response Acceleration – (1 sec), SM1 0.67g* Section 1613.2.3 (Eqn 16-37) 5% Damped Design Spectral Response Acceleration (short), SDS 0.70g Section 1613.2.4 (Eqn 16-38) 5% Damped Design Spectral Response Acceleration (1 sec), SD1 0.447g* Section 1613.2.4 (Eqn 16-39) * Using the code-based values presented in this table, in lieu of a performing a ground motion hazard analysis, requires the exceptions outlined in ASCE 7-16 Section 11.4.8 be followed by the project structural engineer. Per Section 11.4.8 of ASCE/SEI 7-16, a ground motion hazard analysis should be performed for projects for Site Class “E” sites with Ss greater than or equal to 1.0g and for Site Class “D” and “E” sites with S1 greater than 0.2g. Section 11.4.8 also provides exceptions which indicates that the ground motion hazard analysis may be waived provided the exceptions are followed. 8.6.2 Table 8.6.2 presents the mapped maximum considered geometric mean (MCEG) seismic design parameters for projects located in Seismic Design Categories of D through F in accordance with ASCE 7-16. TABLE 8.6.2 ASCE 7-16 PEAK GROUND ACCELERATION Parameter Value ASCE 7-16 Reference Mapped MCEG Peak Ground Acceleration, PGA 0.405g Figure 22-7 Site Coefficient, FPGA 1.195 Table 11.8-1 Site Class Modified MCEGPeak Ground Acceleration, PGAM 0.484g Section 11.8.3 (Eqn 11.8-1) 8.6.3 The project structural engineer and architect should evaluate the appropriate Risk Category and Seismic Design Category for the planned structures. The values presented herein assume a Risk Category of II and resulting in a Seismic Design Category D. Geocon Project No. 06442-32-34 - 12 - May 26, 2021 8.6.4 Conformance to the criteria in Tables 8.6.1 and 8.6.2 for seismic design does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur if a large earthquake occurs. The primary goal of seismic design is to protect life, not to avoid all damage, since such design may be economically prohibitive. 8.7 Shallow Foundations 8.7.1 The project is suitable for the use of continuous strip footings, isolated spread footings, or appropriate combinations thereof, provided the preceding grading recommendations are followed. The following recommendations are for the planned structures and assume that the foundation system for the structures will bear entirely on compacted fill and soil within 3 feet of finish grade consists of very low to low expansive soils (EI <50). 8.7.2 Foundations for the planned structures may consist of continuous strip footings and/or isolated spread footings. Table 8.7 provides a summary of the foundation design recommendations. TABLE 8.7 SUMMARY OF FOUNDATION RECOMMENDATIONS Parameter Value - Parking Garage Footings Bearing on Very Old Paralic Deposits Minimum Continuous Foundation Width 12 inches Minimum Isolated Foundation Width 24 inches Minimum Foundation Depth 24 Inches Below Lowest Adjacent Grade Minimum Steel Reinforcement 4 No. 5 Bars, 2 at the Top and 2 at the Bottom Allowable Bearing Capacity 2,500 psf Bearing Capacity Increase 500 psf per Foot of Depth 300 psf per Foot of Width Maximum Allowable Bearing Capacity 4,000 psf Estimated Total Settlement 1 Inch Estimated Differential Settlement ½ Inch in 40 Feet Design Expansion Index 50 or less 8.7.3 The foundations should be embedded in accordance with the recommendations herein and the Wall/Column Footing Dimension Detail. The embedment depths should be measured from the lowest adjacent pad grade for both interior and exterior footings. Footings should be deepened such that the bottom outside edge of the footing is at least 7 feet horizontally from the face of the slope (if applicable). Geocon Project No. 06442-32-34 - 13 - May 26, 2021 Wall/Column Footing Dimension Detail 8.7.4 The bearing capacity values presented herein are for dead plus live loads and may be increased by one-third when considering transient loads due to wind or seismic forces. 8.7.5 Consideration should be given to connecting patio slabs, which exceed 5 feet in width, to the building foundation to reduce the potential for future separation to occur. 8.7.6 Where buildings or other improvements are planned near the top of a slope steeper than 3:1 (horizontal:vertical), special foundations and/or design considerations are recommended due to the tendency for lateral soil movement to occur. For fill slopes less than 20 feet high and cut slopes regardless of height, building footings should be deepened such that the bottom outside edge of the footing is at least 7 feet horizontally from the face of the slope. Based on the conceptual grading plan, the planned buildings are located at least 60 feet from the top of existing descending fill slopes. Geocon Inc. should be contacted if planned buildings are re-located to near top of descending slopes so that we may provide additional foundation recommendations to help reduce potential foundation distress associated with slope creep and lateral fill extension. Although other improvements, which are relatively rigid or brittle, such as concrete flatwork or masonry walls, may experience some distress if located near the top of a slope, it is generally not economical to mitigate this potential. It may be possible, however, to incorporate design measures that would permit some lateral soil movement without causing extensive distress. Geocon Incorporated should be consulted for specific recommendations. 8.7.7 We should observe the foundation excavations prior to the placement of reinforcing steel and concrete to check that the exposed soil conditions are similar to those expected and that they have been extended to the appropriate bearing strata. Foundation modifications may be required if unexpected soil conditions are encountered. Geocon Project No. 06442-32-34 - 14 - May 26, 2021 8.7.8 Geocon Incorporated should be consulted to provide additional design parameters as required by the structural engineer. 8.8 Interior Concrete Slabs-on-Grade 8.8.1 Concrete slabs-on-grade for the structures should be constructed in accordance with Table 8.8. TABLE 8.8 MINIMUM CONCRETE SLAB-ON-GRADE RECOMMENDATIONS Parameter Building Slab-On- Grade Minimum Concrete Slab Thickness 5.0 inches Minimum Steel Reinforcement No. 3 Bars 18 Inches on Center, Both Directions Typical Slab Underlayment 3 to 4 Inches of Sand/Gravel/Base Design Expansion Index 50 or less 8.8.2 The concrete slab-on-grade recommendations are based on soil support characteristics only. If the slabs will be subjected to heavy loads, consideration should be given to increasing the slab thickness and reinforcement. The project structural engineer should design interior concrete slabs-on-grade that will be subjected to heavy loading (i.e., fork lift, heavy storage areas). Subgrade soils supporting heavy loaded slabs should be compacted to at least 95 percent relative compaction. 8.8.3 Slabs that may receive moisture-sensitive floor coverings or may be used to store moisture- sensitive materials should be underlain by a vapor retarder. The vapor retarder design should be consistent with the guidelines presented in the American Concrete Institute’s (ACI) Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials (ACI 302.2R-06). In addition, the membrane should be installed in accordance with manufacturer’s recommendations and ASTM requirements and installed in a manner that prevents puncture. The vapor retarder used should be specified by the project architect or developer based on the type of floor covering that will be installed and if the structure will possess a humidity controlled environment. 8.8.4 The project foundation engineer, architect, and/or developer should determine the thickness of bedding sand below the building slabs. In general, 3 to 4 inches of sand bedding is typically used. Geocon should be contacted to provide recommendations if the bedding sand is thicker than 6 inches. Geocon Project No. 06442-32-34 - 15 - May 26, 2021 8.8.5 The foundation design engineer should provide appropriate concrete mix design criteria and curing measures to assure proper curing of the slab by reducing the potential for rapid moisture loss and subsequent cracking and/or slab curl. We suggest that the foundation design engineer present the concrete mix design and proper curing methods on the foundation plan. The foundation contractor should understand and follow the specifications presented on the foundation plan. 8.8.6 To control the location and spread of concrete shrinkage and/or expansion cracks, it is recommended that crack-control joints be included in the design of concrete slabs. Crack- control joint spacing should not exceed, in feet, twice the recommended slab thickness in inches (e.g., 10 feet by 10 feet for a 5-inch-thick slab). Crack-control joints should be created while the concrete is still fresh using a grooving tool or shortly thereafter using saw cuts. The structural engineer should take criteria of the American Concrete Institute into consideration when establishing crack-control spacing patterns. 8.8.7 Special subgrade presaturation is not deemed necessary prior to placing concrete; however, the exposed foundation and slab subgrade soil should be moisturized to maintain a moist condition as would be expected in any such concrete placement. 8.8.8 The recommendations of this report are intended to reduce the potential for cracking of slabs due to expansive soil (if present), differential settlement of existing soil or soil with varying thicknesses. However, even with the incorporation of the recommendations presented herein, foundations, stucco walls, and slabs-on-grade placed on such conditions may still exhibit some cracking due to soil movement and/or shrinkage. The occurrence of concrete shrinkage cracks is independent of the supporting soil characteristics. Their occurrence may be reduced and/or controlled by limiting the slump of the concrete, proper concrete placement and curing, and by the placement of crack control joints at periodic intervals, in particular, where re-entrant slab corners occur. 8.9 Conventional Retaining Wall Recommendations 8.9.1 Retaining walls should be designed using the values presented in Table 8.9.1. Soil with an expansion index (EI) greater than 50 should not be used as backfill material behind retaining walls. Geocon Incorporated should be consulted to provide additional design parameters if backfill material possess an EI greater than 50 or as required by the structural engineer. Geocon Project No. 06442-32-34 - 16 - May 26, 2021 TABLE 8.9.1 RETAINING WALL DESIGN RECOMMENDATIONS Parameter Value Active Soil Pressure, A (Fluid Density, Level Backfill) 35 pcf Active Soil Pressure, A (Fluid Density, 2:1 Sloping Backfill) 50 psf Seismic Pressure, S 13H psf At-Rest/Restrained Walls Additional Uniform Pressure (0 to 8 Feet High) 7H psf At-Rest/Restrained Walls Additional Uniform Pressure (8+ Feet High) 13H psf H equals the height of the retaining portion of the wall. 8.9.2 The project retaining walls should be designed as shown in the Retaining Wall Loading Diagram. Retaining Wall Loading Diagram 8.9.3 Where walls are restrained from movement at the top (at-rest condition), an additional uniform pressure of 7H psf should be added to the active soil pressure for walls 8 feet or less. For walls greater than 8 feet tall, an additional uniform pressure of 13H psf should be applied to the wall starting at 8 feet from the top of the wall to the base of the wall. For retaining walls subject to vehicular loads within a horizontal distance equal to two-thirds the wall height, a surcharge equivalent to 2 feet of fill soil should be added (soil total unit weight 130 pcf). IF PRESENT RETAINING WALL ,_,,, ;:::;:. ~1\\--::::;,._,., H (Feet) FOOTING ACTIVE PRESSURE SEISMIC (IF REQUIRED) AT-REST/ RESTRAINED (IF REQUIRED) r 7H H S8' H>8' 14e------l l-------.. 13H psi Geocon Project No. 06442-32-34 - 17 - May 26, 2021 8.9.4 The structural engineer should determine the Seismic Design Category for the project in accordance with Section 1613.2.5 of the 2019 CBC or Section 11.6 of ASCE 7-16. For structures assigned to Seismic Design Category of D, E, or F, retaining walls that support more than 6 feet of backfill should be designed with seismic lateral pressure in accordance with Section 1803.5.12 of the 2019 CBC. The seismic load is dependent on the retained height where H is the height of the wall, in feet, and the calculated loads result in pounds per square foot (psf) exerted at the base of the wall and zero at the top of the wall. A seismic load of 21H psf should be used for design. We used the peak ground acceleration adjusted for Site Class effects, PGAM, of 0.484g calculated from ASCE 7-16 Section 11.8.3 and applied a pseudo-static coefficient of 0.33. 8.9.5 Retaining walls should be designed to ensure stability against overturning, sliding, and excessive foundation pressure. Where a keyway is extended below the wall base with the intent to engage passive pressure and enhance sliding stability, it is not necessary to consider active pressure on the keyway. 8.9.6 Drainage openings through the base of the wall (weep holes) should not be used where the seepage could be a nuisance or otherwise adversely affect planned and existing improvements adjacent to the base of the wall. The recommendations herein assume a properly compacted granular (EI ≤50) free-draining backfill material with no hydrostatic forces or imposed surcharge load. The retaining wall should be properly drained as shown in the Typical Retaining Wall Drainage Detail. If conditions different than those described are expected, or if specific drainage details are desired, Geocon Incorporated should be contacted for additional recommendations. Typical Retaining Wall Drainage Detail H PROPOSED GRADE GROUND SURFACE TEMPORARY BACKCUT PER OSHA OR 4" DIA. PERFORATED SCHEDULE 40 PVC PIPE EXTENDED TO APPROVED OUTLET PROPOSED GRADE RETAINING WALL 213H GROUND SURFACE WATER PROOFING PER ARCHITECT DRAINAGE PANEL (MIRADRAIN 6000 OR EQUIVALENT) 3/4" CRUSHED ROCK 12" 1 (1 CU.FT JFT.) OR WRAP DRAINAGla PANEL AROUND PIPE -7 ~ C .'~''\'" V LTEIHABRI i ,>\: , . ENVELOPE \)\1 MIRAFI 140N OR 1--il•:' w~!'"i:J EQUIVALENT 4" DIA SCHEDULE 40 PERFORATED PVC PIP!;: OR TOTAL DRAIN EXTENDED TO APPROVED OUTLET Geocon Project No. 06442-32-34 - 18 - May 26, 2021 8.9.7 The retaining walls may be designed using either the active and restrained (at-rest) loading condition or the active and seismic loading condition as suggested by the structural engineer. Typically, it appears the design of the restrained condition for retaining wall loading may be adequate for the seismic design of the retaining walls. However, the active earth pressure combined with the seismic design load should be reviewed and considered in the design of the retaining walls. 8.9.8 Wall foundations should be designed in accordance with Table 8.9.2. The proximity of the foundation to the top of a slope steeper than 3:1 could impact the allowable soil bearing pressure. Therefore, retaining wall foundations should be deepened such that the bottom outside edge of the footing is at least 7 feet horizontally from the face of the slope. TABLE 8.9.2 SUMMARY OF RETAINING WALL FOUNDATION RECOMMENDATIONS Parameter Value Minimum Retaining Wall Foundation Width 12 inches Minimum Retaining Wall Foundation Depth 18 Inches Minimum Steel Reinforcement Per Structural Engineer Bearing Capacity 2,500 psf Bearing Capacity Increase 500 psf per additional foot of footing depth 300 psf per additional foot of footing width Maximum Bearing Capacity 4,000 psf Estimated Total Settlement 1 Inch Estimated Differential Settlement ½ Inch in 40 Feet 8.9.9 The recommendations presented herein are generally applicable to the design of rigid concrete or masonry retaining walls. In the event that other types of walls (such as mechanically stabilized earth [MSE] walls, soil nail walls, or soldier pile walls) are planned, Geocon Incorporated should be consulted for additional recommendations. 8.9.10 Unrestrained walls will move laterally when backfilled and loading is applied. The amount of lateral deflection is dependent on the wall height, the type of soil used for backfill, and loads acting on the wall. The retaining walls and improvements above the retaining walls should be designed to incorporate an appropriate amount of lateral deflection as determined by the structural engineer. 8.9.11 Soil contemplated for use as retaining wall backfill, including import materials, should be identified in the field prior to backfill. At that time, Geocon Incorporated should obtain samples for laboratory testing to evaluate its suitability. Modified lateral earth pressures may be Geocon Project No. 06442-32-34 - 19 - May 26, 2021 necessary if the backfill soil does not meet the required expansion index or shear strength. City or regional standard wall designs, if used, are based on a specific active lateral earth pressure and/or soil friction angle. Geocon Incorporated should be consulted to assess the suitability of the on-site soil for use as wall backfill if standard wall designs will be used. 8.10 Lateral Loading 8.10.1 Table 8.10 should be used for the design of footings or shear keys to help design the proposed structures and improvements to resist lateral loads. The allowable passive pressure assumes a horizontal surface extending at least 5 feet, or three times the surface generating the passive pressure, whichever is greater. The upper 12 inches of material in areas not protected by floor slabs or pavement should not be included in design for passive resistance. Where walls are planned adjacent to and/or on descending slopes, a passive pressure of 150 pcf should be used in design. TABLE 8.10 SUMMARY OF LATERAL LOAD DESIGN RECOMMENDATIONS Parameter Value Passive Pressure Fluid Density 300 pcf Passive Pressure Fluid Density Adjacent to and/or on Descending Slopes 150 pcf Coefficient of Friction (Concrete and Soil) 0.40 Coefficient of Friction (Along Vapor Barrier) 0.2 to 0.25* * Per manufacturer’s recommendations. 8.10.2 The passive and frictional resistant loads can be combined for design purposes. The lateral passive pressures may be increased by one-third when considering transient loads due to wind or seismic forces. 8.11 Preliminary Pavement Recommendations – Flexible and Rigid 8.11.1 The preliminary sections presented herein are for budgetary estimating purposes only and are not for construction. The final pavement sections will be provided after the grading operations are completed, subgrade soils are sampled, and laboratory resistance value (R- Value) testing is performed on the soil samples collected. 8.11.2 The preliminary pavement section recommendations are for areas that will be used as passenger vehicle parking, car/light truck and heavy truck driveways. The project civil engineer or traffic engineer should determine the appropriate Traffic Index (TI) or traffic loading expected on the project for the various pavement areas that will be constructed. Geocon Project No. 06442-32-34 - 20 - May 26, 2021 8.11.3 We evaluated the flexible pavement sections in accordance with State of California, Department of Transportation (Caltrans) Highway Design Manual (Topic 633). We used an estimated R-Value of 35 and 78 for soil and aggregate base, respectively, to calculate the preliminary pavement sections. The structural sections presented herein are in accordance with City of Carlsbad minimum requirements for private commercial/industrial developments. Table 8.11.1 summarizes preliminary flexible pavement sections. TABLE 8.11.1 PRELIMINARY ASPHALT CONCRETE PAVEMENT SECTIONS Traffic Index* Asphalt Concrete (inches)** Class 2 Base (inches) 4.5 4.0 4.0 5.0 4.0 4.0 5.5 4.0 4.0 6.0 4.0 5.5 6.5 4.0 7.0 7.0 4.0 8.0 *Civil engineer should provide TI for final pavement design. **City of Carlsbad minimums for Private Commercial/Industrial developments. 8.11.4 Prior to placing base materials and asphalt concrete, the upper 12 inches of the subgrade soil should be scarified, moisture conditioned as necessary, mixed and compacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content as determined by ASTM D1557. Similarly, the base material should be compacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content. Asphalt concrete should be compacted to a density of at least 95 percent of the laboratory Hveem density in accordance with ASTM D 2726. 8.11.5 A rigid Portland cement concrete (PCC) pavement section should be placed in driveway entrance aprons and trash bin loading/storage areas. The concrete pad for the trash truck areas should be large enough such that the truck wheels will be positioned on the concrete during loading. We calculated the rigid pavement section in general conformance with the procedure recommended by the American Concrete Institute report ACI 330R-08 Guide for Design and Construction of Concrete Parking Lots using the parameters presented in Table 8.11.2. Geocon Project No. 06442-32-34 - 21 - May 26, 2021 TABLE 8.11.2 RIGID PAVEMENT DESIGN PARAMETERS Design Parameter Design Value Modulus of subgrade reaction, k 200 pci Modulus of rupture for concrete, MR 550 psi Concrete Compressive Strength 3,200 psi Traffic Category, TC A, B and C Average daily truck traffic, ADTT 10 (TC=A), 25 (TC=B), and 700 (TC=C) 8.11.6 Based on the criteria presented herein, the PCC pavement sections should have a minimum thickness as presented in Table 8.11.3. TABLE 8.11.3 PRELIMINARY RIGID VEHICULAR PAVEMENT RECOMMENDATIONS Location Portland Cement Concrete (inches) Automobile Parking Stalls 5.0 Automobile/Light Truck Driveways 6.0 Heavy/Trash Truck Driveways/Fire Lane 7.0 Heavy Truck Loading Apron 7.0 Trash Enclosure Apron 7.5* *City of Carlsbad minimums for Private Commercial/Industrial developments. 8.11.7 Prior to placing PCC slabs, the upper 12 inches of pavement subgrade soils should be scarified, moisture conditioned as necessary, mixed and compacted to a dry density of at least 95 percent of the laboratory maximum dry density at to slightly above optimum moisture content in accordance with ASTM D 1557. 8.11.8 The rigid pavement should also be designed and constructed incorporating the parameters presented in Table 8.11.4. Geocon Project No. 06442-32-34 - 22 - May 26, 2021 TABLE 8.11.4 ADDITIONAL RIGID PAVEMENT RECOMMENDATIONS Subject Value Thickened Edge 1.2 Times Slab Thickness Minimum Increase of 2 Inches 3 Feet Wide Crack Control Joint Spacing 30 Times Slab Thickness Max. Spacing of 12 feet for 5.5-Inch-Thick Max. Spacing of 15 Feet for Slabs 6 Inches and Thicker Crack Control Joint Depth Per ACI 330R-08 1 Inch Using Early-Entry Saws on Slabs Less Than 9 Inches Thick Crack Control Joint Width ¼-Inch for Sealed Joints ⅜-Inch is Common for Sealed Joints 1/10- to 1/8-Inch is Common for Unsealed Joints 8.11.9 Rigid pavement should be reinforced with No. 3 reinforcing bars spaced 24 inches on center in both directions placed at the slab midpoint. 8.11.10 Loading aprons such as trash bin enclosures and heavy truck areas should utilize Portland cement concrete as presented in Table 8.11.3 above. The concrete loading area should extend out such that both the front and rear wheels of the truck will be located on reinforced concrete pavement when loading and unloading. 8.11.11 To control the location and spread of concrete shrinkage cracks, crack-control joints (weakened plane joints) should be included in the design of the concrete pavement slab. Crack-control joints should be sealed with an appropriate sealant to prevent the migration of water through the control joint to the subgrade materials. The depth of the crack-control joints should be determined by the referenced ACI report. 8.11.12 To provide load transfer between adjacent pavement slab sections, a butt-type construction joint should be constructed. The butt-type joint should be thickened by at least 20 percent at the edge and taper back at least 4 feet from the face of the slab. The project structural engineer should be consulted to provide other alternative recommendations for load transfer (i.e., dowels). Geocon Project No. 06442-32-34 - 23 - May 26, 2021 8.11.13 Concrete curb/gutter should be placed on soil subgrade compacted to a dry density of at least 90 percent of the laboratory maximum dry density near to slightly above optimum moisture content. Cross-gutters that receives vehicular traffic should be placed on subgrade soil compacted to a dry density of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture content. 8.11.14 The performance of pavement is highly dependent on providing positive surface drainage away from the edge of the pavement. Ponding of water on or adjacent to the pavement will likely result in pavement distress and subgrade failure. Drainage from landscaped areas should be directed to controlled drainage structures. Landscape areas adjacent to the edge of asphalt pavements are not recommended due to the potential for surface or irrigation water to infiltrate the underlying permeable aggregate base and cause distress. Where such a condition cannot be avoided, consideration should be given to incorporating measures that will significantly reduce the potential for subsurface water migration into the aggregate base. If planter islands are planned, the perimeter curb should extend at least 6 inches below the level of the base materials. 8.12 Exterior Concrete Flatwork 8.12.1 Exterior concrete flatwork not subject to vehicular traffic should be constructed in accordance with the recommendations presented in Table 8.12. The recommended steel reinforcement would help reduce the potential for cracking. TABLE 8.12 MINIMUM CONCRETE FLATWORK RECOMMENDATIONS Expansion Index, EI Minimum Reinforcing Steel* Minimum Thickness EI < 50 6x6-W2.9/W2.9 (6x6-6/6) welded wire mesh 4 Inches No. 3 Bars 24 inches on center, Both Directions * In excess of 8 feet square. 8.12.2 Even with the incorporation of the recommendations of this report, the exterior concrete flatwork has a potential to experience some uplift due to expansive soil (if present) beneath grade. The reinforcing steel should overlap continuously in flatwork to reduce the potential for vertical offsets within flatwork. Additionally, flatwork should be structurally connected to the curbs, where possible, to reduce the potential for offsets between the curbs and the flatwork. Geocon Project No. 06442-32-34 - 24 - May 26, 2021 8.12.3 Concrete flatwork should be provided with crack control joints to reduce and/or control shrinkage cracking. Crack control spacing should be determined by the project structural engineer based upon the slab thickness and intended usage. Criteria of the American Concrete Institute (ACI) should be taken into consideration when establishing crack control spacing. Subgrade soil for exterior slabs not subjected to vehicle loads should be compacted in accordance with criteria presented in the grading section prior to concrete placement. Subgrade soil should be properly compacted, and the moisture content of subgrade soil should be verified prior to placing concrete. Base materials will not be required below concrete improvements. 8.12.4 Where exterior flatwork abuts the structure at entrant or exit areas, the exterior slab should be dowelled into the structure’s foundation stemwall. This recommendation is intended to reduce the potential for differential elevations that could result from differential settlement or minor heave of the flatwork. The project structural engineer should provide dowelling details. 8.12.5 The recommendations presented herein are intended to reduce the potential for cracking of exterior slabs as a result of differential movement. However, even with the incorporation of the recommendations presented herein, slabs-on-grade will still crack. The occurrence of concrete shrinkage cracks is independent of the soil supporting characteristics. Their occurrence may be reduced and/or controlled by limiting the slump of the concrete, the use of crack control joints and proper concrete placement and curing. Crack control joints should be spaced at intervals no greater than 12 feet. Literature provided by the Portland Concrete Association (PCA) and American Concrete Institute (ACI) present recommendations for proper concrete mix, construction, and curing practices, and should be incorporated into project construction. 8.13 Storm Water Management (Detention Basin and Bioswales) 8.13.1 The lot is currently underlain by compacted fill and dense granitic rock. Planned grading will result with these units at grade. As previously discussed, the compacted fill consists of silty sands, and mixtures of angular gravel and boulders generated from blasting operations in granitic rock. Soils consisting of sandy clays were placed in deeper fill areas. Infiltrating into compacted fill generally results in settlement and distress to improvements placed over the compacted fill; as well as slope instability. It is our opinion the compacted fill is unsuitable for infiltration of storm water runoff due to the potential for adverse settlement and slope instability. The granitic bedrock is also sufficiently dense that infiltration water would be expected to perch on this unit. Geocon Project No. 06442-32-34 - 25 - May 26, 2021 8.13.2 Detention basins, bioswales and bio-remediation areas should be designed by the project civil engineer and reviewed by Geocon Incorporated. Typically, bioswales consist of a surface layer of vegetation underlain by clean sand. A subdrain should be provided beneath the sand layer. Prior to discharging into the storm drain pipe, a seepage cutoff wall should be constructed at the interface between the subdrain and storm drain pipe. The concrete cut-off wall should extend at least 6-inches beyond the perimeter of the gravel-packed subdrain system. 8.13.3 Distress may be caused to planned improvements and properties located hydrologically downgradient or adjacent to infiltration devices. The distress depends on the amount of water to be detained, its residence time, soil permeability, and other factors. We have not performed a hydrogeology study at the site. Downstream and adjacent properties may be subjected to seeps, springs, slope instability, raised groundwater, movement of foundations and slabs, or other impacts as a result of water infiltration. Due to site soil and geologic conditions, permanent bioswales and bio-remediation areas should be lined with an impermeable liner to prevent water infiltration in to the underlying compacted fill. Temporary detention basins in areas where improvements have not been constructed do not need to be lined. 8.13.4 Appendix C presents the form titled Categorization of Infiltration Feasibility Condition (Form I-8) from the City of Carlsbad BMP Design Manual (February 16, 2016). 8.13.5 The landscape architect should be consulted to provide the appropriate plant recommendations. If drought resistant plants are not used, irrigation may be required. 8.14 Site Drainage and Moisture Protection 8.14.1 Adequate site drainage is critical to reduce the potential for differential soil movement, erosion and subsurface seepage. Water should not be allowed to pond adjacent to footings. The site should be graded and maintained such that surface drainage is directed away from structures in accordance with 2019 CBC 1803.3 or other applicable standards. In addition, surface drainage should be directed away from the top of slopes into swales or other controlled drainage devices. Roof and pavement drainage should be directed into conduits that carry runoff away from the proposed structures. 8.14.2 In the case of basement walls or building walls retaining landscaping areas, a water-proofing system should be used on the wall and joints, and a Miradrain drainage panel (or similar) should be placed over the waterproofing. The project architect or civil engineer should provide detailed specifications on the plans for all waterproofing and drainage. Geocon Project No. 06442-32-34 - 26 - May 26, 2021 8.14.3 Underground utilities should be leak free. Utility and irrigation lines should be checked periodically for leaks, and detected leaks should be repaired promptly. Detrimental soil movement could occur if water is allowed to infiltrate the soil for prolonged periods of time. 8.14.4 Landscaping planters adjacent to paved areas are not recommended due to the potential for surface or irrigation water to infiltrate the pavement's subgrade and base course. We recommend that subdrains to collect excess irrigation water and transmit it to drainage structures, or impervious above-grade planter boxes be used. In addition, where landscaping is planned adjacent to the pavement, we recommend construction of a cutoff wall along the edge of the pavement that extends at least 6 inches below the bottom of the base material. 8.15 Slope Maintenance 8.15.1 Slopes that are steeper than 3:1 (horizontal:vertical) may, under conditions that are both difficult to prevent and predict, be susceptible to near-surface (surficial) slope instability. The instability is typically limited to the outer 3 feet of a portion of the slope and usually does not directly impact the improvements on the pad areas above or below the slope. The occurrence of surficial instability is more prevalent on fill slopes and is generally preceded by a period of heavy rainfall, excessive irrigation, or the migration of subsurface seepage. The disturbance and/or loosening of the surficial soils, as might result from root growth, soil expansion, or excavation for irrigation lines and slope planting, may also be a significant contributing factor to surficial instability. It is therefore recommended that, to the maximum extent practical: (a) disturbed/loosened surficial soils be either removed or properly recompacted, (b) irrigation systems be periodically inspected and maintained to eliminate leaks and excessive irrigation, and (c) surface drains on and adjacent to slopes be periodically maintained to preclude ponding or erosion. Although the incorporation of the above recommendations should reduce the potential for surficial slope instability, it will not eliminate the possibility and, therefore, it may be necessary to rebuild or repair a portion of the project's slopes in the future. 8.16 Grading, Foundation and Retaining Wall Plan Review 8.16.1 Geocon Incorporated should review the grading, foundation and retaining wall plans for the project prior to final design submittal to evaluate whether additional analyses and/or recommendations are required. Geocon Project No. 06442-32-34 May 26, 2021 LIMITATIONS AND UNIFORMITY OF CONDITIONS 1. The firm that performed the geotechnical investigation for the project should be retained to provide testing and observation services during construction to provide continuity of geotechnical interpretation and to check that the recommendations presented for geotechnical aspects of site development are incorporated during site grading, construction of improvements, and excavation of foundations. If another geotechnical firm is selected to perform the testing and observation services during construction operations, that firm should prepare a letter indicating their intent to assume the responsibilities of project geotechnical engineer of record. A copy of the letter should be provided to the regulatory agency for their records. In addition, that firm should provide revised recommendations concerning the geotechnical aspects of the proposed development, or a written acknowledgement of their concurrence with the recommendations presented in our report. They should also perform additional analyses deemed necessary to assume the role of Geotechnical Engineer of Record. 2. The recommendations of this report pertain only to the site investigated and are based upon the assumption that the soil conditions do not deviate from those disclosed in the investigation. If any variations or undesirable conditions are encountered during construction, or if the proposed construction will differ from that anticipated herein, Geocon Incorporated should be notified so that supplemental recommendations can be given. The evaluation or identification of the potential presence of hazardous or corrosive materials was not part of the scope of services provided by Geocon Incorporated. 3. This report is issued with the understanding that it is the responsibility of the owner or his representative to ensure that the information and recommendations contained herein are brought to the attention of the architect and engineer for the project and incorporated into the plans, and the necessary steps are taken to see that the contractor and subcontractors carry out such recommendations in the field. 4. The findings of this report are valid as of the present date. However, changes in the conditions of a property can occur with the passage of time, whether they be due to natural processes or the works of man on this or adjacent properties. In addition, changes in applicable or appropriate standards may occur, whether they result from legislation or the broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period of three years. SITESITE NO SCALE FIG. 1 THE GEOGRAPHICAL INFORMATION MADE AVAILABLE FOR DISPLAY WAS PROVIDED BY GOOGLE EARTH,SUBJECT TO A LICENSING AGREEMENT. THE INFORMATION IS FOR ILLUSTRATIVE PURPOSES ONLY; IT ISNOT INTENDED FOR CLIENT'S USE OR RELIANCE AND SHALL NOT BE REPRODUCED BY CLIENT. CLIENTSHALL INDEMNIFY, DEFEND AND HOLD HARMLESS GEOCON FROM ANY LIABILITY INCURRED AS A RESULTOF SUCH USE OR RELIANCE BY CLIENT. VICINITY MAP 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974 PHONE 858 558-6900 - FAX 858 558-6159 DSK/GTYPD PROJECT NO. 06442 - 32 - 34EA / CW CARLSBAD OAKS NORTH BUSINESS PARK LOT 3 CARLSBAD, CALIFORNIAGEOTECHNICAL ENVIRONMENTAL MATERIALS Plotted:05/26/2021 9:10AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\06442-32-34 (Con Lot-3)\DETAILS\06442-32-34 Vic Map.dwg DATE 05 - 26 - 2021 t N GEOCON INCORPORATED ■ ■ I I 3 2 0 33 0 34 0 35 0 36 0 37 0 3 1 0 3 2 0 33 0 34 0 35 0 360 3 2 5 3 1 5 31 5 32 5 3 3 5 34 5 355 365 36 5 35 5 34 5 33 5 BUILDING "A" BUILDING "B" BUILDING "C" 2 2 2 2 22 2 2 22 3 1 11 1 1 3 3 3 3 3 3 3 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 3 3 3 3 4 4 4 44 4 4 4 5 5 66 6 6 6 7 7 6 6 7 6 3 4 Kgr T-7 T-9 T-8 T-1 T-2 T-5 T-3 T-4 T-6 295 273 350 343 324 304 317 304 312 299 307 296 297 284 276 269 260 270 284 298 309 312 296 298 299 284 271 269 258 290 308 Qcf/ Qcf/ Qcf/ Qcf/ Kgr Kgr C' C B' BA A' Qcf/ PROPERTY BOUNDARY Kgr T-7 T-9 T-8 T-1 T-2 T-5 T-3 T-4 T-6 295 273 350 343 324 304 317 304 312 299 307 296 297 284 276 269 260 270 284 298 309 312 296 298 299 284 271 269 258 290 308 Qcf/ Qcf/ Qcf/ Qcf/ Kgr Kgr C' C B' BA A' Qcf/ PROPERTY BOUNDARY 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974 PHONE 858 558-6900 - FAX 858 558-6159 SHEET OF PROJECT NO. SCALE DATE FIGURE Plotted:05/26/2021 9:03AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\06442-32-34 (Con Lot-3)\SHEETS\06442-32-34 GeologicMAP.dwg GEOTECHNICAL ENVIRONMENTAL MATERIALS 1" = GEOLOGIC 1AP CARLSBAD OAKS NORTH BUSINESS PARK - LOT 3 CARLSBAD, CALIFORNIA 30' 05 - 26 - 2021 06442 - 32 - 34 1 1 2 252 257 T-9 GEOCON LEGEND ........COMPACTED FILLQcf ........APPROX. LOCATION OF EXPLORATORY TRENCH EXCAVATIONS ........APPROX. LOCATION OF GEOLOGIC CONTACT ........APPROX. LOCATION OF GEOLOGIC CROSS-SECTIONC C' ........GRANITIC ROCK (Dotted Where Buried)Kgr ........APPROX. BOTTOM ELEVATION OF COMPACTED FILL ........APPROX. ELEVATION OF CANYON SUBDRAIN ........APPROX. LOCATION OF EXISTING CANYON SUBDRAIN -- - ~ \9 s I 20 s--s '<.'vi R'vl ----R'vl -------R'vl ,_,..-,-,-0 1 i'\\ .1 Q ~ \: ~ I \ (/) L... I\ ! -\ -- ,. " I I I 111111t---l-!-___J 1.50 TW I 324.90 1G i25!50 FG I B?4,40 I I 111111111111 [ 1111 11 I 11111 J2 .80 TC J2 .JO FL (/) L... - , ,., "'T -- -- - \ \ ~~,'FibJLl ARf R/SfRiWoM ~_l_\ARf SPR/N/(1.fR p()C >< \ 'o 1t I (/) ~ F==+s=i===--_;_~Jt~l )l f\11: I --- : 1\J \ ~~____c:::~G.__-~J~II ~~ _'-'=' I O' \ Fft= 322,50 g \ PE 321.79 \ 0 \ 0 ' I I b. _I '"Q ~ '"Q S..J---- 321.JO TC WJ.BIJ Fl Sci ~ s S..J : .. :-·= •••••• • • • • ••• . . .... : . \ ••••• \ 310- - "' C o· !!!!!!lii.1!!!!!!5~30~'~ ~7~;~~~~~----~ 60' S 90' CALE 1" 30' 120' (On 36x24} "'""' ~ ""' c:::::J I\ r--.../ 9f2gcoN ORATED ■ ■ EL E V A T I O N ( M S L ) EL E V A T I O N ( M S L ) DISTANCE (FEET) SCALE: 1" = 30' (Vert. = Horiz.) GEOLOGIC CROSS-SECTION A-A' 270 300 330 360 390 270 300 330 360 390 0 30 60 90 120 150 180 210 240 270 300 330 EL E V A T I O N ( M S L ) EL E V A T I O N ( M S L ) DISTANCE (FEET) SCALE: 1" = 30' (Vert. = Horiz.) GEOLOGIC CROSS-SECTION B-B' 270 300 330 360 390 270 300 330 360 390 0 30 60 90 120 150 180 210 240 270 300 330 360 EL E V A T I O N ( M S L ) EL E V A T I O N ( M S L ) DISTANCE (FEET) SCALE: 1" = 30' (Vert. = Horiz.) GEOLOGIC CROSS-SECTION C-C' 240 270 300 330 360 390 240 270 300 330 360 390 0 30 60 90 120 150 180 210 240 270 300 330 360 390 400 A A' C B B' C' EXISTING GRADE ? ? Kgr Kgr Kgr Qcf PROPOSED DRIVEISLE PROPOSED BLDG C PROPOSED DRIVEISLE EXISTING WHIPTAILLOOP WEST (ROW) PL PROPOSEDRETAININGWALL PL PROPOSED GRADE T-6(Projected Approx. 10' North) T-2(Projected Approx.40' South)T-9(Projected Approx.15' South) Kgr Qcf Kgr Qcf EXISTING GRADEPROPOSED GRADE PL PROPOSED DRIVE ISLE PROPOSED BLDG B PROPOSED DRIVEISLE PROPOSEDBIO-BASIN EXISTING WHIPTAILLOOP WEST (ROW) PL ???? ? Kgr Qcf Qcf Qcf Kgr Kgr ? ? ? ? EXISTING GRADE PROPOSED GRADE EXISTING CANYONSUBDRAIN PL PROPOSEDBIO-BASIN PROPOSEDDRIVE ISLE PROPOSED BLDG A PROPOSED DRIVE ISLE PROPOSED BIO-BASIN EXISTING WHIPTAILLOOP WEST (ROW) PL 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974 PHONE 858 558-6900 - FAX 858 558-6159 SHEET OF PROJECT NO. SCALE DATE FIGURE Plotted:05/26/2021 9:07AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\06442-32-34 (Con Lot-3)\SHEETS\06442-32-34 Cross-Section.dwg GEOTECHNICAL ENVIRONMENTAL MATERIALS 1" = GEOLOGIC CROSS - SEC8ION CARLSBAD OAKS NORTH BUSINESS PARK - LOT 3 SAN DIEGO, CALIFORNIA 30' 05 - 26 - 2021 06442 - 32 - 34 1 1 3 T-9 ? GEOCON LEGEND ........COMPACTED FILLQcf ........APPROX. LOCATION OF EXPLORATORY TRENCH EXCAVATION ........APPROX. LOCATION OF GEOLOGIC CONTACT (Queried Where Uncertain) ........GRANITIC ROCKKgr - - - - - - - - - - ' ' ' ' ' ' ' ' ' ' I ' -+ -+ -+ -+ -+ -+ -+ -+ -+ -+ - -~-+--I --~ -~-~ - t F -l--t= ~ -+ ~ -+ -f------1 --+ -+ ~ -+ H -+ --+ I -~ I--7 ---r-' I ---r-I I I I I I I I I ' ' ' I I I I I I I I I I I --f--1---+--f---1--t-_, ' -t -I-_J -I----,_ I I L +-I +-' I -+--+--~ ---+---- -+ I --+ -+ H -+ t ' --i I +--~K' -~-+----~ 1 - --+-t r I I ---t-----, ' I 'I ' --t ' ' ---, ' ---t-f----t'.--I ' _J_ L ~ -+-~ ~ +---+ =+ -_, ~ -i= -' --~-,~L I ? ~ i J +-H -~ F -_, F --=r R~ "-r-:J -'' h-F -F -+ ~ -- ---+ -f H ---+ --t---+ 4 ·-t----4 +--+ ~ L ---I -I--, I I I -- ' f-+ '-I-' ---l--I-- I~ I t--+ L I t-I I +-t--l F ~ -~ --~ --~-~ -+ --+ -+ ----4 ---+ F ,_ --+ ---+ ~ -+ --4 - -+-=i j-~ +-----+--+- -+ -+ +-H --+ --+ --+ --+ l--+ ' H - .------,----,-----,----,---,-----,--,-----r----c---T----r-,------,----,-----,----,-----,-----,--,-----r----,-----,-----r-,-----,----,-----,----,-----,-----,--,-----r----,-----,-----r-,------,----,-----,----,-----,-----,--,-----r----.------,-----r-,------,--""T"""""T"---,-----,-----,--,-----r----,-----,-----r-,------,----,-----,----,---,-----,-, - -+ --+ -t-i --+ --+ --+ -~-F ---- --+ ~ --+ ---t ---+ ---+ -f--1-::--i r ' ' ::-t --1-1-~ -t-~ I I --- -- -- - --+ --+ +------J t--+ t--+--+ t - •_::=t I f -- -1-rr ---j---- - -I I 11 ,_ -I I - - -r I I I ,-1--l-I I I J_ ' -I I f - --..! -e-' -v =t-i 7 t---+ /r -- 1T 1T I-- I I I I I I I I ---,_ -,_ - -' ' -j---I-r-4 - - H --+ t -- --+ --+-+--I--+ +-+-+__,-~- ---+ ---+ ' ' I I -- +--+ +--t f--= --,_ ft +-,-~ +--+ +---+ - - -f\ +--+---+ -,_ t-,- --+ -- ---+ -- --+ j _, __ 1--l----- -,-- I -----,---- ii+--+-+-+-+-+-H_ ::-t +-__J_ c---+--- - I I - _,_ - - -j-,-- I It-----1T1--T1 T -- I I I I I I I I 1-+-+--+-+---1-+-+--+--+--+-+-+---+-+--+-+---i-+-+--+--+--+-+-+---+-+--+-+---i-+-+--+--+--+-+-+---+-+--+-+---i-+-+--+--+--+-+-+-I +-' -+---+' -+T----i'-+-+--+--+I -+T __,1-+-_+-_-+-I --+--+1-+-H I I - ' I I I --,--,-- -- -j--t-R t--- -j- --4 ---4 --4 ---4 - I ,--,-- - -t-R t-- --4 --4 I -,- j-- --4 - --t----4 I_,_ - j--------j l_-t-, I -1: -----t t -t t I ---- I I I I , , I I I , I I I I I , I I , , I I I , I I I I I , I I , I I 77' 11m ' --' ' ' ' ' ' ' 1--1-1--t i-1 ~1 t f f -le" t I ,-1 --tli t j ,-t ,_ --,_ - +-,ttt-H--t ,--t--I t H-, ---1-1--t-+ I I I I I I I t-7 +t-J I ' f- 1 --'-I I LJ ~ ...... ,-~ -- ;v -T ___j_____J ----:,._ --t -t t 1 t ~ t H J t -t t--t I' ~ t -,. + tt- ,_ -f ---t · -I I ' I --' f-t ' ~L I I I ' ' ' +f t t ---l-1-+--+-+--1-- J t t l j t 1 l l,_ -+t [: --t t -+ti t = t t -t t t -t -- ' ' t-+-r---j f-~ l GEOCON l N C O R POR AT ED e l----'------r------1 ■ ■ APPENDIX A Geocon Project No. 06442-32-34 May 26, 2021 APPENDIX A Rippability Study We performed the field investigation on October 28 and November 3, 2020. The study consisted of excavating nine backhoe trenches utilizing a C345BL trackhoe equipped with a 2-foot-wide bucket. The exploratory trench logs are presented in Appendix A, Figures A-1 through A-9. The approximate locations of the exploratory trenches are shown on Figure 2 (map pocket). We visually examined, classified, and logged the soil conditions encountered in general accordance with American Society for Testing and Materials (ASTM) practice for Description and Identification of Soils (Visual-Manual Procedure D 2488). 330' 325' 320' 315' Kgr 1 2 GRANITIC ROCK (Kgr) Moderately weathered, damp to moist, mottled olive and grayish brown, strong to very strong GRANITIC ROCK; excavates to a mottled olive and grayish brown, soil-rock mix with rock up to 2 foot diameter and trace rounded core stones up to 18 inch diameter Very strong to extremely strong with trace rounded core stones up to 3foot diameter: Refusal at bottom of excavation -No groundwater -Backfilled with trench spoils 1 2 GROUND SURFACE Kgr EL E V A T I O N ( F E E T ) , M S L 0' DISTANCE (FEET) 5'10'15'20' CORE STONES CORE STONES EXISTINGIRRIGATIONLINE 335' REFUSAL FIG. A1 TRENCH NO. 1 SCALE : 1" = 5' (VERT. = HORIZ.) 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974 PHONE 858 558-6900 - FAX 858 558-6159 DSK/GTYPD PROJECT NO. 06442 - 32 - 34EA / CW CARLSBAD OAKS NORTH BUSINESS PARK LOT 3 CARLSBAD, CALIFORNIAGEOTECHNICAL ENVIRONMENTAL MATERIALS Plotted:05/26/2021 9:11AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\06442-32-34 (Con Lot-3)\DETAILS\06442-32-34_TRENCHES.dwg DATE 05 - 26 - 2021 0 0 0 GEOCON INCORPORATED ■ ■ I I 330' 325' 320' Moderately to slightly weathered, damp, mottled olive and grayish brown, very strong GRANITIC ROCK; excavates to rock up to 3 foot diameter with little/some silty, fine to coarse sand; Refusal at bottom of excavation -No groundwater -Backfilled with trench spoils 1 GROUND SURFACE Kgr 1 0' DISTANCE (FEET) 5'10'15'20' EL E V A T I O N ( F E E T ) , M S L GRANITIC ROCK (Kgr) 335' 340' EXISTING IRRIGATION LINE REFUSAL 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974 PHONE 858 558-6900 - FAX 858 558-6159 DSK/GTYPD PROJECT NO. 06442 - 32 - 34EA / CW CARLSBAD OAKS NORTH BUSINESS PARK LOT 3 CARLSBAD, CALIFORNIAGEOTECHNICAL ENVIRONMENTAL MATERIALS Plotted:05/26/2021 9:11AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\06442-32-34 (Con Lot-3)\DETAILS\06442-32-34_TRENCHES.dwg DATE 05 - 26 - 2021 FIG. A2 TRENCH NO. 2 SCALE : 1" = 5' (VERT. = HORIZ.) 0 GEOCON INCORPORATED ■ ■ I I 340' 335' 330' 325' 320' 315' Highly weathered, damp, mottled orange and olive brown, weak tomoderately week GRANITIC ROCK; excavates to a mottled orangeand olive brown, silty, fine to coarse sand with little weak rock up to 1 foot diameter and few rounded core stones up to 18 inch diameter. -Few rounded core stones up to 3 foot diameter at 10 feet; no refusal -No groundwater -Backfilled with trench spoils 0' DISTANCE (FEET) 10'20'30' CORE STONES Kgr 1 EL E V A T I O N ( F E E T ) , M S L 1 EXISTINGIRRIGATIONLINE Kgr EXISTING GROUND SURFACE Kgr 5'15'25'352' 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974 PHONE 858 558-6900 - FAX 858 558-6159 DSK/GTYPD PROJECT NO. 06442 - 32 - 34EA / CW CARLSBAD OAKS NORTH BUSINESS PARK LOT 3 CARLSBAD, CALIFORNIAGEOTECHNICAL ENVIRONMENTAL MATERIALS Plotted:05/26/2021 9:11AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\06442-32-34 (Con Lot-3)\DETAILS\06442-32-34_TRENCHES.dwg DATE 05 - 26 - 2021 FIG. A3 TRENCH NO. 3 SCALE : 1" = 5' (VERT. = HORIZ.) 0 GEOCON INCORPORATED ■ ■ I I 340' 335' 330' 325' 320' 315' 0' DISTANCE (FEET) 10'20'30'40' EL E V A T I O N ( F E E T ) , M S L EXISTING IRRIGATION LINE Kgr Kgr Kgr FRESHCORE STONE(SPANS TRENCH WIDTH) EXISTINGGROUND SURFACE 5'15'25'35' 1 Highly weathered, damp, mottled orange and olive brown, weak tomoderately week GRANITIC ROCK; excavates to a mottled orangeand olive brown, silty, fine to coarse sand with few/little weak rock up to8 inch diameter -Few rounded core stones up to 18 inch diameter; no refusal -No groundwater -Backfilled with trench spoils 1 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974 PHONE 858 558-6900 - FAX 858 558-6159 DSK/GTYPD PROJECT NO. 06442 - 32 - 34EA / CW CARLSBAD OAKS NORTH BUSINESS PARK LOT 3 CARLSBAD, CALIFORNIAGEOTECHNICAL ENVIRONMENTAL MATERIALS Plotted:05/26/2021 9:11AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\06442-32-34 (Con Lot-3)\DETAILS\06442-32-34_TRENCHES.dwg DATE 05 - 26 - 2021 FIG. A4 TRENCH NO. 4 SCALE : 1" = 5' (VERT. = HORIZ.) 0 GEOCON INCORPORATED ■ ■ I I COMPACTED FILL Loose to medium dense, damp, mottled olive and orange brown, Silty, fine to coarse SAND with few gravel up to 6 inch diameter -Becomes medium dense, moist at 1 foot GRANITIC ROCK Highly weathered, moist, mottled orange and olive brown, weak to moderately weak GRANITIC ROCK; excavates as silty, fine to coarse sand with few to little weak rock and rounded core stones up to 18 inch diameter -Heavy trenching effort at 7 feet; trace core stones up to 3 foot diameter -Practical refusal due to large rounded core stones (diameter > 5 feet) BOTTOM OF TRENCH AT 9 FEET Practical refusal on core stones No groundwater Backfilled with trench spoils SM ... DISTURBED OR BAG SAMPLE GEOCON DEPTH IN FEET 0 2 4 6 8 Figure A-5, Log of Trench T 5, Page 1 of 1 DR Y D E N S I T Y (P . C . F . ) ... DRIVE SAMPLE (UNDISTURBED) C345BL W/ 2' BUCKET & ROCK TEETH PE N E T R A T I O N RE S I S T A N C E (B L O W S / F T . ) TRENCH T 5 ... CHUNK SAMPLE DATE COMPLETED ... SAMPLING UNSUCCESSFUL SOIL CLASS (USCS) GR O U N D W A T E R E. ALVARADO CO N T E N T ( % ) SAMPLE NO.11-03-2020 SAMPLE SYMBOLS MO I S T U R E BY:EQUIPMENT ELEV. (MSL.)324' 06442-32-34.GPJ MATERIAL DESCRIPTION LI T H O L O G Y ... STANDARD PENETRATION TEST ... WATER TABLE OR ... SEEPAGE NOTE: PROJECT NO. THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. 06442-32-34 ,... ,... - ,... - ,... - ,... - ,... - ,... - ,... - ,... - ,... ----r-r-y tTt .-.1--L-1- + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + I] liiiiJ - - - - - - - - COMPACTED FILL Medium dense, damp, mottled olive and orange brown Silty, fine to coarse SAND with trace gravel GRANITIC ROCK Highly weathered, damp, mottled orange and olive brown, weak to moderately weak GRANITIC ROCK; excavates as silty, fine to coarse sand with weak rock and rounded core stones up to 3 foot diameter -No refusal BOTTOM OF TRENCH AT 12 FEET No groundwater Backfilled with trench spoils SM ... DISTURBED OR BAG SAMPLE GEOCON DEPTH IN FEET 0 2 4 6 8 10 12 Figure A-6, Log of Trench T 6, Page 1 of 1 DR Y D E N S I T Y (P . C . F . ) ... DRIVE SAMPLE (UNDISTURBED) C345BL W/ 2' BUCKET & ROCK TEETH PE N E T R A T I O N RE S I S T A N C E (B L O W S / F T . ) TRENCH T 6 ... CHUNK SAMPLE DATE COMPLETED ... SAMPLING UNSUCCESSFUL SOIL CLASS (USCS) GR O U N D W A T E R E. ALVARADO CO N T E N T ( % ) SAMPLE NO.11-03-2020 SAMPLE SYMBOLS MO I S T U R E BY:EQUIPMENT ELEV. (MSL.)324' 06442-32-34.GPJ MATERIAL DESCRIPTION LI T H O L O G Y ... STANDARD PENETRATION TEST ... WATER TABLE OR ... SEEPAGE NOTE: PROJECT NO. THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. 06442-32-34 ,... ,... - ,... - ,... - ,... - ,... - ,... - ,... - ,... - ,... - ,... - ,... - ,... ----r-r-y (f:f:r + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + I] liiiiJ - - - - - - - - - - COMPACTED FILL Medium dense, damp, mottled olive and orange brown, Silty, fine to coarse SAND with trace gravel up to 4 inch diameter -Becomes moist at 1 foot GRANITIC ROCK Completely to highly weathered, damp, mottled orange and olive brown, weak GRANITIC ROCK; excavates as silty, fine to coarse sand with few weak rock up to 4 inch diameter -Trace rounded core stones up to 8 inch diameter -Becomes highly weathered at 7 feet BOTTOM OF TRENCH AT 10 FEET No groundwater Backfilled with trench spoil SM ... DISTURBED OR BAG SAMPLE GEOCON DEPTH IN FEET 0 2 4 6 8 10 Figure A-7, Log of Trench T 7, Page 1 of 1 DR Y D E N S I T Y (P . C . F . ) ... DRIVE SAMPLE (UNDISTURBED) C345BL W/ 2' BUCKET & ROCK TEETHPE N E T R A T I O N RE S I S T A N C E (B L O W S / F T . ) TRENCH T 7 ... CHUNK SAMPLE DATE COMPLETED ... SAMPLING UNSUCCESSFUL SOIL CLASS (USCS) GR O U N D W A T E R E. ALVARADOCO N T E N T ( % ) SAMPLE NO.11-03-2020 SAMPLE SYMBOLS MO I S T U R E BY:EQUIPMENT ELEV. (MSL.)321' 06442-32-34.GPJ MATERIAL DESCRIPTION LI T H O L O G Y ... STANDARD PENETRATION TEST ... WATER TABLE OR... SEEPAGE NOTE: PROJECT NO. THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. 06442-32-34 ts. - - - - - - - - - ~ ■ ~ [I ~ □ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + .. -L.J_.-1 - I-- I-- I-- I-- I-- I-- I-- I-- I-- - COMPACTED FILL Medium dense, damp, mottled orange and olive brown, Silty, fine to coarse SAND with trace gravel up to 4 inch diameter GRANITIC ROCK Highly weathered, damp, mottled orange and olive brown, weak GRANITIC ROCK; excavates as silty, fine to coarse sand with little weak rock up to 10 inch diameter and trace rounded core stones up to 12 inch diameter -Becomes moderately weak to moderately strong at 5 feet BOTTOM OF TRENCH AT 11 FEET No groundwater Backfilled with trench spoils SM ... DISTURBED OR BAG SAMPLE GEOCON DEPTH IN FEET 0 2 4 6 8 10 Figure A-8, Log of Trench T 8, Page 1 of 1 DR Y D E N S I T Y (P . C . F . ) ... DRIVE SAMPLE (UNDISTURBED) C345BL W/ 2' BUCKET & ROCK TEETH PE N E T R A T I O N RE S I S T A N C E (B L O W S / F T . ) TRENCH T 8 ... CHUNK SAMPLE DATE COMPLETED ... SAMPLING UNSUCCESSFUL SOIL CLASS (USCS) GR O U N D W A T E R E. ALVARADO CO N T E N T ( % ) SAMPLE NO.11-03-2020 SAMPLE SYMBOLS MO I S T U R E BY:EQUIPMENT ELEV. (MSL.)321' 06442-32-34.GPJ MATERIAL DESCRIPTION LI T H O L O G Y ... STANDARD PENETRATION TEST ... WATER TABLE OR ... SEEPAGE NOTE: PROJECT NO. THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. 06442-32-34 ,... ,... - ,... - ,... - ,... - ,... - ,... - ,... - ,... - ,... - ,... - ,... ----r-r-y (f:f:r + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + I] liiiiJ - - - - - - - - - COMPACTED FILL Medium dense, damp, mottled olive and orange brown, Silty, fine to coarse SAND with trace gravel up to 4 inch diameter GRANITIC ROCK Highly to moderately weathered, damp, mottled orange and olive brown, moderately weak GRANITIC ROCK; excavates as silty, fine to coarse sand with some rock up to 18 inch diameter and trace rounded core stones up to 2 foot diameter -Becomes moderately weak to moderately strong at 7 feet with trace rock up to 4 foot diameter -Moderate to heavy trenching effort at 8 feet; excavates to a soil-rock mix with rock up to 18 inch diameter BOTTOM OF TRENCH AT 10 FEET No groundwater Backfilled with trench spoils SM ... DISTURBED OR BAG SAMPLE GEOCON DEPTH IN FEET 0 2 4 6 8 10 Figure A-9, Log of Trench T 9, Page 1 of 1 DR Y D E N S I T Y (P . C . F . ) ... DRIVE SAMPLE (UNDISTURBED) C345BL W/ 2' BUCKET & ROCK TEETH PE N E T R A T I O N RE S I S T A N C E (B L O W S / F T . ) TRENCH T 9 ... CHUNK SAMPLE DATE COMPLETED ... SAMPLING UNSUCCESSFUL SOIL CLASS (USCS) GR O U N D W A T E R E. ALVARADO CO N T E N T ( % ) SAMPLE NO.11-03-2020 SAMPLE SYMBOLS MO I S T U R E BY:EQUIPMENT ELEV. (MSL.)319' 06442-32-34.GPJ MATERIAL DESCRIPTION LI T H O L O G Y ... STANDARD PENETRATION TEST ... WATER TABLE OR ... SEEPAGE NOTE: PROJECT NO. THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES. 06442-32-34 ,... ----1--·t •·1· _: :---.. ---r-:-:- + + ,... -+ + + + + + ,... -+ + + + ,... -+ + + + + ,... -+ + + + + + ,... -+ + + + ,... -+ + + + + + ,... -+ + + + + ,... -+ + + + ,... -+ + + + + + ,... I] liiiiJ I - - - - - - - - - APPENDIX B APPENDIX B LABORATORY TESTING PERFORMED BY GEOCON INCORPORATED (2006) FOR CARLSBAD OAKS NORTH BUSINESS PARK – LOT 3 CARLSBAD, CALIFORNIA PROJECT NO. 06442-32-34 Geocon Project No. 06442-32-34 May 26, 2021 APPENDIX B LABORATORY TESTING TABLE B-I SUMMARY OF LABORATORY MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT TEST RESULTS ASTM D 1557 Sample No.(Unit) Description Maximum Dry Density (pcf) Optimum Moisture Content (% dry wt.) 1 Dark brown, Silty, fine SAND 129.2 8.5 2 Olive brown, Silty, fine to coarse SAND with trace gravel 130.1 8.6 4 Very dark brown, Clayey, fine to medium SAND, with trace gravel 123.9 12.0 5 Dark reddish brown, Clayey, fine to coarse SAND with trace gravel 135.1 7.4 TABLE B-II SUMMARY OF LABORATORY DIRECT SHEAR TEST RESULTS AASHTO T236 Sample No. Dry Density (pcf) Moisture Content (%) Unit Cohesion (psf) Angle of Shear Resistance (degrees) 5 121.5 7.4 1015 48 TABLE B-III SUMMARY OF LABORATORY EXPANSION INDEX TEST RESULTS ASTM D 4829 Sample No. (Unit) Moisture Content Dry Density (pcf) Expansion Index Before Test (%) After Test (%) EI-14 (Lot 3) 9.0 16.5 113.0 1 EI-15 (Lot 3) 9.3 14.9 113.9 2 EI-16 (Lot 3) 8.4 14.2 117.8 1 TABLE B-IV SUMMARY OF LABORATORY WATER-SOLUBLE SULFATE TEST RESULTS CALIFORNIA TEST NO. 417 Sample No. (Unit) Water-Soluble Sulfate (%) Sulfate Exposure EI-14 (Lot 3) 0.002 Negligible EI-15 (Lot 3) 0.008 Negligible EI-16 (Lot 3) 0.004 Negligible APPENDIX C APPENDIX C CITY OF CARLSBAD BMP DESIGN MANUAL – CATEGORIZATION OF INFILTRATION FEASIBILITY CONDITION (FORM I-8) FOR CARLSBAD OAKS NORTH BUSINESS PARK – LOT 3 CARLSBAD, CALIFORNIA PROJECT NO. 06442-32-34 Appendix I: Forms and Checklists I-3 February 2016 Categorization of Infiltration Feasibility Condition Form I-8 Part 1 - Full Infiltration Feasibility Screening Criteria Would infiltration of the full design volume be feasible from a physical perspective without any undesirable consequences that cannot be reasonably mitigated? Criteria Screening Question Yes No 1 Is the estimated reliable infiltration rate below proposed facility locations greater than 0.5 inches per hour? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. X Provide basis: As discussed in Sections 4 and 8.13 of the update geotechnical report, the lot consists of dense to very stiff compacted fill overlying hard granitic rock. The bedrock is also exposed at grade. After planned grading, the compacted fill will be approximately 5 to 55 feet thick and bedrock will also be near or at grade. Previous infiltration testing performed on other lots within the Carlsbad Oaks North Business Park with similar soil conditions (see Geocon Inc., report titled Update Geotechnical Report, Carlsbad Oaks North Business Park – Lot 17, Carlsbad, California, dated March 25, 2016 (Proeject No. 06442-32-21) indicated a factored infiltration rate between 10-4 to 10-1 iph (after applying a feasibility factor of safety of 2). 2 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. X Provide basis: The site is underlain by dense to very stiff compacted fill overlying hard granitic rock. After planned grading, the compacted fill will be approximately 5 to 50 feet thick and bedrock will also be near or at grade. Based on existing and ultimate geologic conditions, infiltration could not be incorporated without increasing the risk of geotechnical hazards including uncontrolled water lateral migration, shrinking and swelling, induced hydro-compression of the fill and water migration within pipe zone of underground utilities. Appendix I: Forms and Checklists I-4 February 2016 Form I-8 Page 2 of 4 Criteria Screening Question Yes No 3 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of groundwater contamination (shallow water table, storm water pollutants or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. X Provide basis: Groundwater is not located within 10 feet of proposed BMP basins. The risk of storm water infiltration adversely impacting groundwater is considered negligible. 4 Can infiltration greater than 0.5 inches per hour be allowed without causing potential water balance issues such as change of seasonality of ephemeral streams or increased discharge of contaminated groundwater to surface waters? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Researching downstream water rights and evaluating water balance issues to stream flows is beyond the scope of the geotechnical engineer. Part 1 Result * If all answers to rows 1 - 4 are “Yes” a full infiltration design is potentially feasible. The feasibility screening category is Full Infiltration If any answer from row 1-4 is “No”, infiltration may be possible to some extent but would not generally be feasible or desirable to achieve a “full infiltration” design. Proceed to Part 2 NO *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by the City to substantiate findings. Appendix I: Forms and Checklists I-5 February 2016 Form I-8 Page 3 of 4 Part 2 – Partial Infiltration vs. No Infiltration Feasibility Screening Criteria Would infiltration of water in any appreciable amount be physically feasible without any negative consequences that cannot be reasonably mitigated? Criteria Screening Question Yes No 5 Do soil and geologic conditions allow for infiltration in any appreciable rate or volume? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. X Provide basis: The site is underlain by dense to very stiff compacted fill overlying hard granitic rock. After planned grading, the compacted fill will be approximately 5 to 50 feet thick. The bedrock is also exposed at grade. Previous infiltration testing performed on other lots within the Carlsbad Oaks North Business Park with similar soil conditions (see Geocon Inc., report titled Update Geotechnical Report, Carlsbad Oaks North Business Park – Lot 17, Carlsbad, California, dated March 25, 2016 (Proeject No. 06442-32-21) indicated a factored infiltration rate between 10-4 to 10-1 iph (after applying a feasibility factor of safety of 2). Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. 6 Can Infiltration in any appreciable quantity be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. X Provide basis: The site is underlain by dense to very stiff compacted fill overlying hard granitic rock. After planned grading, the compacted fill will be approximately 5 to 50 feet thick and bedrock will also be near or at grade. Based on existing and ultimate geologic conditions, infiltration could not be incorporated without increasing the risk of geotechnical hazards including uncontrolled water lateral migration, shrinking and swelling, induced hydro-compression of the fill and water migration within pipe zone of underground utilities. Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. Appendix I: Forms and Checklists I-6 February 2016 Form I-8 Page 4 of 4 Criteria Screening Question Yes No 7 Can Infiltration in any appreciable quantity be allowed without posing significant risk for groundwater related concerns (shallow water table, storm water pollutants or other factors)? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. X Provide basis: Groundwater is not located within 10 feet of proposed BMP basins. The risk of storm water infiltration adversely impacting groundwater is considered negligible. Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. 8 Can infiltration be allowed without violating downstream water rights? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: Researching downstream water rights and evaluating water balance issues to stream flows is beyond the scope of the geotechnical engineer. Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates. Part 2 Result* If all answers from row 5-8 are yes then partial infiltration design is potentially feasible. The feasibility screening category is Partial Infiltration. If any answer from row 5-8 is no, then infiltration of any volume is considered to be infeasible within the drainage area. The feasibility screening category is No Infiltration. No Infiltration *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by the City to substantiate findings. APPENDIX D APPENDIX D RECOMMENDED GRADING SPECIFICATIONS FOR CARLSBAD OAKS NORTH BUSINESS PARK – LOT 3 CARLSBAD, CALIFORNIA PROJECT NO. 06442-32-34 GI rev. 07/2015 RECOMMENDED GRADING SPECIFICATIONS 1. GENERAL 1.1 These Recommended Grading Specifications shall be used in conjunction with the Geotechnical Report for the project prepared by Geocon. The recommendations contained in the text of the Geotechnical Report are a part of the earthwork and grading specifications and shall supersede the provisions contained hereinafter in the case of conflict. 1.2 Prior to the commencement of grading, a geotechnical consultant (Consultant) shall be employed for the purpose of observing earthwork procedures and testing the fills for substantial conformance with the recommendations of the Geotechnical Report and these specifications. The Consultant should provide adequate testing and observation services so that they may assess whether, in their opinion, the work was performed in substantial conformance with these specifications. It shall be the responsibility of the Contractor to assist the Consultant and keep them apprised of work schedules and changes so that personnel may be scheduled accordingly. 1.3 It shall be the sole responsibility of the Contractor to provide adequate equipment and methods to accomplish the work in accordance with applicable grading codes or agency ordinances, these specifications and the approved grading plans. If, in the opinion of the Consultant, unsatisfactory conditions such as questionable soil materials, poor moisture condition, inadequate compaction, and/or adverse weather result in a quality of work not in conformance with these specifications, the Consultant will be empowered to reject the work and recommend to the Owner that grading be stopped until the unacceptable conditions are corrected. 2. DEFINITIONS 2.1 Owner shall refer to the owner of the property or the entity on whose behalf the grading work is being performed and who has contracted with the Contractor to have grading performed. 2.2 Contractor shall refer to the Contractor performing the site grading work. 2.3 Civil Engineer or Engineer of Work shall refer to the California licensed Civil Engineer or consulting firm responsible for preparation of the grading plans, surveying and verifying as-graded topography. 2.4 Consultant shall refer to the soil engineering and engineering geology consulting firm retained to provide geotechnical services for the project. GI rev. 07/2015 2.5 Soil Engineer shall refer to a California licensed Civil Engineer retained by the Owner, who is experienced in the practice of geotechnical engineering. The Soil Engineer shall be responsible for having qualified representatives on-site to observe and test the Contractor's work for conformance with these specifications. 2.6 Engineering Geologist shall refer to a California licensed Engineering Geologist retained by the Owner to provide geologic observations and recommendations during the site grading. 2.7 Geotechnical Report shall refer to a soil report (including all addenda) which may include a geologic reconnaissance or geologic investigation that was prepared specifically for the development of the project for which these Recommended Grading Specifications are intended to apply. 3. MATERIALS 3.1 Materials for compacted fill shall consist of any soil excavated from the cut areas or imported to the site that, in the opinion of the Consultant, is suitable for use in construction of fills. In general, fill materials can be classified as soil fills, soil-rock fills or rock fills, as defined below. 3.1.1 Soil fills are defined as fills containing no rocks or hard lumps greater than 12 inches in maximum dimension and containing at least 40 percent by weight of material smaller than ¾ inch in size. 3.1.2 Soil-rock fills are defined as fills containing no rocks or hard lumps larger than 4 feet in maximum dimension and containing a sufficient matrix of soil fill to allow for proper compaction of soil fill around the rock fragments or hard lumps as specified in Paragraph 6.2. Oversize rock is defined as material greater than 12 inches. 3.1.3 Rock fills are defined as fills containing no rocks or hard lumps larger than 3 feet in maximum dimension and containing little or no fines. Fines are defined as material smaller than ¾ inch in maximum dimension. The quantity of fines shall be less than approximately 20 percent of the rock fill quantity. 3.2 Material of a perishable, spongy, or otherwise unsuitable nature as determined by the Consultant shall not be used in fills. 3.3 Materials used for fill, either imported or on-site, shall not contain hazardous materials as defined by the California Code of Regulations, Title 22, Division 4, Chapter 30, Articles 9 GI rev. 07/2015 and 10; 40CFR; and any other applicable local, state or federal laws. The Consultant shall not be responsible for the identification or analysis of the potential presence of hazardous materials. However, if observations, odors or soil discoloration cause Consultant to suspect the presence of hazardous materials, the Consultant may request from the Owner the termination of grading operations within the affected area. Prior to resuming grading operations, the Owner shall provide a written report to the Consultant indicating that the suspected materials are not hazardous as defined by applicable laws and regulations. 3.4 The outer 15 feet of soil-rock fill slopes, measured horizontally, should be composed of properly compacted soil fill materials approved by the Consultant. Rock fill may extend to the slope face, provided that the slope is not steeper than 2:1 (horizontal:vertical) and a soil layer no thicker than 12 inches is track-walked onto the face for landscaping purposes. This procedure may be utilized provided it is acceptable to the governing agency, Owner and Consultant. 3.5 Samples of soil materials to be used for fill should be tested in the laboratory by the Consultant to determine the maximum density, optimum moisture content, and, where appropriate, shear strength, expansion, and gradation characteristics of the soil. 3.6 During grading, soil or groundwater conditions other than those identified in the Geotechnical Report may be encountered by the Contractor. The Consultant shall be notified immediately to evaluate the significance of the unanticipated condition. 4. CLEARING AND PREPARING AREAS TO BE FILLED 4.1 Areas to be excavated and filled shall be cleared and grubbed. Clearing shall consist of complete removal above the ground surface of trees, stumps, brush, vegetation, man-made structures, and similar debris. Grubbing shall consist of removal of stumps, roots, buried logs and other unsuitable material and shall be performed in areas to be graded. Roots and other projections exceeding 1½ inches in diameter shall be removed to a depth of 3 feet below the surface of the ground. Borrow areas shall be grubbed to the extent necessary to provide suitable fill materials. 4.2 Asphalt pavement material removed during clearing operations should be properly disposed at an approved off-site facility or in an acceptable area of the project evaluated by Geocon and the property owner. Concrete fragments that are free of reinforcing steel may be placed in fills, provided they are placed in accordance with Section 6.2 or 6.3 of this document. GI rev. 07/2015 4.3 After clearing and grubbing of organic matter and other unsuitable material, loose or porous soils shall be removed to the depth recommended in the Geotechnical Report. The depth of removal and compaction should be observed and approved by a representative of the Consultant. The exposed surface shall then be plowed or scarified to a minimum depth of 6 inches and until the surface is free from uneven features that would tend to prevent uniform compaction by the equipment to be used. 4.4 Where the slope ratio of the original ground is steeper than 5:1 (horizontal:vertical), or where recommended by the Consultant, the original ground should be benched in accordance with the following illustration. TYPICAL BENCHING DETAIL Remove All Unsuitable Material As Recommended By Consultant Finish Grade Original Ground Finish Slope Surface Slope To Be Such That Sloughing Or Sliding Does Not Occur Varies “B” See Note 1 No Scale See Note 2 1 2 DETAIL NOTES: (1) Key width "B" should be a minimum of 10 feet, or sufficiently wide to permit complete coverage with the compaction equipment used. The base of the key should be graded horizontal, or inclined slightly into the natural slope. (2) The outside of the key should be below the topsoil or unsuitable surficial material and at least 2 feet into dense formational material. Where hard rock is exposed in the bottom of the key, the depth and configuration of the key may be modified as approved by the Consultant. 4.5 After areas to receive fill have been cleared and scarified, the surface should be moisture conditioned to achieve the proper moisture content, and compacted as recommended in Section 6 of these specifications. --- --... --------------------1 I --------------------'----------'--------... --... ------------------------ ----- GI rev. 07/2015 5. COMPACTION EQUIPMENT 5.1 Compaction of soil or soil-rock fill shall be accomplished by sheepsfoot or segmented-steel wheeled rollers, vibratory rollers, multiple-wheel pneumatic-tired rollers, or other types of acceptable compaction equipment. Equipment shall be of such a design that it will be capable of compacting the soil or soil-rock fill to the specified relative compaction at the specified moisture content. 5.2 Compaction of rock fills shall be performed in accordance with Section 6.3. 6. PLACING, SPREADING AND COMPACTION OF FILL MATERIAL 6.1 Soil fill, as defined in Paragraph 3.1.1, shall be placed by the Contractor in accordance with the following recommendations: 6.1.1 Soil fill shall be placed by the Contractor in layers that, when compacted, should generally not exceed 8 inches. Each layer shall be spread evenly and shall be thoroughly mixed during spreading to obtain uniformity of material and moisture in each layer. The entire fill shall be constructed as a unit in nearly level lifts. Rock materials greater than 12 inches in maximum dimension shall be placed in accordance with Section 6.2 or 6.3 of these specifications. 6.1.2 In general, the soil fill shall be compacted at a moisture content at or above the optimum moisture content as determined by ASTM D 1557. 6.1.3 When the moisture content of soil fill is below that specified by the Consultant, water shall be added by the Contractor until the moisture content is in the range specified. 6.1.4 When the moisture content of the soil fill is above the range specified by the Consultant or too wet to achieve proper compaction, the soil fill shall be aerated by the Contractor by blading/mixing, or other satisfactory methods until the moisture content is within the range specified. 6.1.5 After each layer has been placed, mixed, and spread evenly, it shall be thoroughly compacted by the Contractor to a relative compaction of at least 90 percent. Relative compaction is defined as the ratio (expressed in percent) of the in-place dry density of the compacted fill to the maximum laboratory dry density as determined in accordance with ASTM D 1557. Compaction shall be continuous over the entire area, and compaction equipment shall make sufficient passes so that the specified minimum relative compaction has been achieved throughout the entire fill. GI rev. 07/2015 6.1.6 Where practical, soils having an Expansion Index greater than 50 should be placed at least 3 feet below finish pad grade and should be compacted at a moisture content generally 2 to 4 percent greater than the optimum moisture content for the material. 6.1.7 Properly compacted soil fill shall extend to the design surface of fill slopes. To achieve proper compaction, it is recommended that fill slopes be over-built by at least 3 feet and then cut to the design grade. This procedure is considered preferable to track-walking of slopes, as described in the following paragraph. 6.1.8 As an alternative to over-building of slopes, slope faces may be back-rolled with a heavy-duty loaded sheepsfoot or vibratory roller at maximum 4-foot fill height intervals. Upon completion, slopes should then be track-walked with a D-8 dozer or similar equipment, such that a dozer track covers all slope surfaces at least twice. 6.2 Soil-rock fill, as defined in Paragraph 3.1.2, shall be placed by the Contractor in accordance with the following recommendations: 6.2.1 Rocks larger than 12 inches but less than 4 feet in maximum dimension may be incorporated into the compacted soil fill, but shall be limited to the area measured 15 feet minimum horizontally from the slope face and 5 feet below finish grade or 3 feet below the deepest utility, whichever is deeper. 6.2.2 Rocks or rock fragments up to 4 feet in maximum dimension may either be individually placed or placed in windrows. Under certain conditions, rocks or rock fragments up to 10 feet in maximum dimension may be placed using similar methods. The acceptability of placing rock materials greater than 4 feet in maximum dimension shall be evaluated during grading as specific cases arise and shall be approved by the Consultant prior to placement. 6.2.3 For individual placement, sufficient space shall be provided between rocks to allow for passage of compaction equipment. 6.2.4 For windrow placement, the rocks should be placed in trenches excavated in properly compacted soil fill. Trenches should be approximately 5 feet wide and 4 feet deep in maximum dimension. The voids around and beneath rocks should be filled with approved granular soil having a Sand Equivalent of 30 or greater and should be compacted by flooding. Windrows may also be placed utilizing an "open-face" method in lieu of the trench procedure, however, this method should first be approved by the Consultant. GI rev. 07/2015 6.2.5 Windrows should generally be parallel to each other and may be placed either parallel to or perpendicular to the face of the slope depending on the site geometry. The minimum horizontal spacing for windrows shall be 12 feet center-to-center with a 5-foot stagger or offset from lower courses to next overlying course. The minimum vertical spacing between windrow courses shall be 2 feet from the top of a lower windrow to the bottom of the next higher windrow. 6.2.6 Rock placement, fill placement and flooding of approved granular soil in the windrows should be continuously observed by the Consultant. 6.3 Rock fills, as defined in Section 3.1.3, shall be placed by the Contractor in accordance with the following recommendations: 6.3.1 The base of the rock fill shall be placed on a sloping surface (minimum slope of 2 percent). The surface shall slope toward suitable subdrainage outlet facilities. The rock fills shall be provided with subdrains during construction so that a hydrostatic pressure buildup does not develop. The subdrains shall be permanently connected to controlled drainage facilities to control post-construction infiltration of water. 6.3.2 Rock fills shall be placed in lifts not exceeding 3 feet. Placement shall be by rock trucks traversing previously placed lifts and dumping at the edge of the currently placed lift. Spreading of the rock fill shall be by dozer to facilitate seating of the rock. The rock fill shall be watered heavily during placement. Watering shall consist of water trucks traversing in front of the current rock lift face and spraying water continuously during rock placement. Compaction equipment with compactive energy comparable to or greater than that of a 20-ton steel vibratory roller or other compaction equipment providing suitable energy to achieve the required compaction or deflection as recommended in Paragraph 6.3.3 shall be utilized. The number of passes to be made should be determined as described in Paragraph 6.3.3. Once a rock fill lift has been covered with soil fill, no additional rock fill lifts will be permitted over the soil fill. 6.3.3 Plate bearing tests, in accordance with ASTM D 1196, may be performed in both the compacted soil fill and in the rock fill to aid in determining the required minimum number of passes of the compaction equipment. If performed, a minimum of three plate bearing tests should be performed in the properly compacted soil fill (minimum relative compaction of 90 percent). Plate bearing tests shall then be performed on areas of rock fill having two passes, four passes and six passes of the compaction equipment, respectively. The number of passes required for the rock fill shall be determined by comparing the results of the plate bearing tests for the soil fill and the rock fill and by evaluating the deflection GI rev. 07/2015 variation with number of passes. The required number of passes of the compaction equipment will be performed as necessary until the plate bearing deflections are equal to or less than that determined for the properly compacted soil fill. In no case will the required number of passes be less than two. 6.3.4 A representative of the Consultant should be present during rock fill operations to observe that the minimum number of “passes” have been obtained, that water is being properly applied and that specified procedures are being followed. The actual number of plate bearing tests will be determined by the Consultant during grading. 6.3.5 Test pits shall be excavated by the Contractor so that the Consultant can state that, in their opinion, sufficient water is present and that voids between large rocks are properly filled with smaller rock material. In-place density testing will not be required in the rock fills. 6.3.6 To reduce the potential for “piping” of fines into the rock fill from overlying soil fill material, a 2-foot layer of graded filter material shall be placed above the uppermost lift of rock fill. The need to place graded filter material below the rock should be determined by the Consultant prior to commencing grading. The gradation of the graded filter material will be determined at the time the rock fill is being excavated. Materials typical of the rock fill should be submitted to the Consultant in a timely manner, to allow design of the graded filter prior to the commencement of rock fill placement. 6.3.7 Rock fill placement should be continuously observed during placement by the Consultant. 7. SUBDRAINS 7.1 The geologic units on the site may have permeability characteristics and/or fracture systems that could be susceptible under certain conditions to seepage. The use of canyon subdrains may be necessary to mitigate the potential for adverse impacts associated with seepage conditions. Canyon subdrains with lengths in excess of 500 feet or extensions of existing offsite subdrains should use 8-inch-diameter pipes. Canyon subdrains less than 500 feet in length should use 6-inch-diameter pipes. GI rev. 07/2015 TYPICAL CANYON DRAIN DETAIL 7.2 Slope drains within stability fill keyways should use 4-inch-diameter (or lager) pipes. ........................ NATURAi.GROUND ,,,,,,----- ................. ............ ........ ................... __ -- SEE DETAL BELOW NOTES: 1 ...... 8-lNCH DIAMETER, SCHEDULE 80 PVC PERFORATED PIPE FOR FILLS IN EXCESS OF 100-FEET IN DEPTH ORA PIPE LENGTH OF LONGER THAN 500 FEET. 2 ...... 6-INCH DIAMETER, SCHEDULE 40 PVC PERFORATED PIPE FOR FILLS LESS THAN 100-FEET IN DEPTH OR A PIPE LENGTH SHORTER THAN 500 FEET. ,, ------,- .,,,.,,,,,,,.,,,.. BEDROCK NOTE: FINAL 20' OF PIPEAT CUTI.ET SHALL BE NON-PERFORATED. 9 CUBIC FEET/ FOOT OF OPEN GRADED GRAVEL SURROUNDED BY MIRAF1140NC (OR EQUIVALENT) FILTER FABRIC NO SCALE GI rev. 07/2015 TYPICAL STABILITY FILL DETAIL 7.3 The actual subdrain locations will be evaluated in the field during the remedial grading operations. Additional drains may be necessary depending on the conditions observed and the requirements of the local regulatory agencies. Appropriate subdrain outlets should be evaluated prior to finalizing 40-scale grading plans. 7.4 Rock fill or soil-rock fill areas may require subdrains along their down-slope perimeters to mitigate the potential for buildup of water from construction or landscape irrigation. The subdrains should be at least 6-inch-diameter pipes encapsulated in gravel and filter fabric. Rock fill drains should be constructed using the same requirements as canyon subdrains. DETAIL NOTES: FORMAnONAL MATERIAL 1 ..... EXCAVATE BACKCUT AT 1:1 INCUNATION (UNLESS OTHERWISE NOTl:D~ 2 .... .BASE OF STABILITY FILL TO BE 3 FEET INTO FORMATIONAL MATERIAL, SI.OPING A MINIMUM 5% INTO SLOPE. 3 ..... STABIUTY FLL TO BE COMF'OSED OF PROPERLY COMPACTED GRANIA..AR SOIL 4 ..... CHIMNEY DRAINS TO BE APPROVED PREFABRICATED CHIMNEY DRAIN PANELS (MIRADRAIN G200N OR EQUIVALENT) SPACED AF'PROXIMATELY 20 FEET CENTER TO CENTER AND 4 FEETWIDE. CLOSER SPACING MAY BE REQUIRED F SEEPAGE IS ENCOUNTERED. 5 ..... FILTER MATERIAL TO BE 314-tlCH, OPEN-GRADED CRUSI-IED ROCK ENCLOSED IN APPROVED FL TER FABRIC (MIRAFI 1-40NC~ 6 ..... COLLECTOR PIPE TO BE 4-INCH MINIMUM DIAMETER, PERFORATED, THICK-WALLED PVC SCHEDULE 40 OR EQUIVALENT, AND SLOPED TO DRAIN AT 1 PERCENT lilNMUM TO APPROVED oun.ET. NO SCALE GI rev. 07/2015 7.5 Prior to outletting, the final 20-foot segment of a subdrain that will not be extended during future development should consist of non-perforated drainpipe. At the non-perforated/ perforated interface, a seepage cutoff wall should be constructed on the downslope side of the pipe. TYPICAL CUT OFF WALL DETAIL 7.6 Subdrains that discharge into a natural drainage course or open space area should be provided with a permanent headwall structure. FRONT VIEW SIDE VIEW ' CONCRETE CUT-OFF WAU. CONCRETE CUT-OFFWAU. SOLID SlJBDRAII P1PE ',( / 8' MIN. NO SCALE ll" MIN.(TYP) ll" MIN.(TYP) / NO SCALE GI rev. 07/2015 TYPICAL HEADWALL DETAIL 7.7 The final grading plans should show the location of the proposed subdrains. After completion of remedial excavations and subdrain installation, the project civil engineer should survey the drain locations and prepare an “as-built” map showing the drain locations. The final outlet and connection locations should be determined during grading operations. Subdrains that will be extended on adjacent projects after grading can be placed on formational material and a vertical riser should be placed at the end of the subdrain. The grading contractor should consider videoing the subdrains shortly after burial to check proper installation and functionality. The contractor is responsible for the performance of the drains. FRONT VIEW SIDE VIEW 8"0R8" SUBDRAIN CONCRETE fEADWALL 8" ORB" SUBDRAIN ~ 24" NOTE: HEADWALL SHOULD ounET AT TOE OF FILL SLOPE OR INTO CONTROLLED SURFACE DRAINAGE NO SCALE 12" NO SCALE GI rev. 07/2015 8. OBSERVATION AND TESTING 8.1 The Consultant shall be the Owner’s representative to observe and perform tests during clearing, grubbing, filling, and compaction operations. In general, no more than 2 feet in vertical elevation of soil or soil-rock fill should be placed without at least one field density test being performed within that interval. In addition, a minimum of one field density test should be performed for every 2,000 cubic yards of soil or soil-rock fill placed and compacted. 8.2 The Consultant should perform a sufficient distribution of field density tests of the compacted soil or soil-rock fill to provide a basis for expressing an opinion whether the fill material is compacted as specified. Density tests shall be performed in the compacted materials below any disturbed surface. When these tests indicate that the density of any layer of fill or portion thereof is below that specified, the particular layer or areas represented by the test shall be reworked until the specified density has been achieved. 8.3 During placement of rock fill, the Consultant should observe that the minimum number of passes have been obtained per the criteria discussed in Section 6.3.3. The Consultant should request the excavation of observation pits and may perform plate bearing tests on the placed rock fills. The observation pits will be excavated to provide a basis for expressing an opinion as to whether the rock fill is properly seated and sufficient moisture has been applied to the material. When observations indicate that a layer of rock fill or any portion thereof is below that specified, the affected layer or area shall be reworked until the rock fill has been adequately seated and sufficient moisture applied. 8.4 A settlement monitoring program designed by the Consultant may be conducted in areas of rock fill placement. The specific design of the monitoring program shall be as recommended in the Conclusions and Recommendations section of the project Geotechnical Report or in the final report of testing and observation services performed during grading. 8.5 We should observe the placement of subdrains, to check that the drainage devices have been placed and constructed in substantial conformance with project specifications. 8.6 Testing procedures shall conform to the following Standards as appropriate: 8.6.1 Soil and Soil-Rock Fills: 8.6.1.1 Field Density Test, ASTM D 1556, Density of Soil In-Place By the Sand-Cone Method. GI rev. 07/2015 8.6.1.2 Field Density Test, Nuclear Method, ASTM D 6938, Density of Soil and Soil-Aggregate In-Place by Nuclear Methods (Shallow Depth). 8.6.1.3 Laboratory Compaction Test, ASTM D 1557, Moisture-Density Relations of Soils and Soil-Aggregate Mixtures Using 10-Pound Hammer and 18-Inch Drop. 8.6.1.4. Expansion Index Test, ASTM D 4829, Expansion Index Test. 9. PROTECTION OF WORK 9.1 During construction, the Contractor shall properly grade all excavated surfaces to provide positive drainage and prevent ponding of water. Drainage of surface water shall be controlled to avoid damage to adjoining properties or to finished work on the site. The Contractor shall take remedial measures to prevent erosion of freshly graded areas until such time as permanent drainage and erosion control features have been installed. Areas subjected to erosion or sedimentation shall be properly prepared in accordance with the Specifications prior to placing additional fill or structures. 9.2 After completion of grading as observed and tested by the Consultant, no further excavation or filling shall be conducted except in conjunction with the services of the Consultant. 10. CERTIFICATIONS AND FINAL REPORTS 10.1 Upon completion of the work, Contractor shall furnish Owner a certification by the Civil Engineer stating that the lots and/or building pads are graded to within 0.1 foot vertically of elevations shown on the grading plan and that all tops and toes of slopes are within 0.5 foot horizontally of the positions shown on the grading plans. After installation of a section of subdrain, the project Civil Engineer should survey its location and prepare an as-built plan of the subdrain location. The project Civil Engineer should verify the proper outlet for the subdrains and the Contractor should ensure that the drain system is free of obstructions. 10.2 The Owner is responsible for furnishing a final as-graded soil and geologic report satisfactory to the appropriate governing or accepting agencies. The as-graded report should be prepared and signed by a California licensed Civil Engineer experienced in geotechnical engineering and by a California Certified Engineering Geologist, indicating that the geotechnical aspects of the grading were performed in substantial conformance with the Specifications or approved changes to the Specifications. Geocon Project No. 06442-32-34 May 26, 2021 LIST OF REFERENCES 1. Bay Area Earthquake Alliance (2020), How Close To a Fault Do You Live?: Website, https://bayquakealliance.org/howclose/, accessed July 15, 2020; 2. Jennings, C. W., 1994, California Division of Mines and Geology, Fault Activity Map of California and Adjacent Areas, California Geologic Data Map Series Map No. 6. 3. SEAOC (2019), OSHPD Seismic Design Maps: Structural Engineers Association of California website, http://seismicmaps.org/, accessed May 24, 2021; 4. USGS (2019), Quaternary Fault and Fold Database of the United States: U.S. Geological Survey website, https://www.usgs.gov/natural-hazards/earthquake-hazards/faults, accessed April 26, 2021; 5. Kennedy, M. P., and S. S. Tan, Geologic Map of the Oceanside 30’x60’ Quadrangle, California, USGS Regional Map Series Map No. 2, Scale 1:100,000, 2007. 6. Unpublished reports and maps on file with Geocon Incorporated.