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Home My WebLink AboutPUD 16-08; COVE DRIVE CONDOMINIUMS; GEOTECHNICAL UPDATE REPORT; 2016-07-25Geotechnical Update Report Proposed Residential Duplex Development Existing Pad (Lot 31) 4547 Cove Drive Carlsbad, California July 25, 2016 FEB 05 2018 LAND DEVELOPMENT Prepared For: ENGINEERING Mr. Kyle Stephens Kyle Stephens & Associates 1350 Columbia Street, Suite 702 San Diego, California 92101 Prepared By: SMS GEOTECHNICAL SOLUTIONS, INC. 5931 Sea Lion Place, Suite 109 Carlsbad, California 92010 Project No. GI-16-06-128 4 mc (9 L~~ SMS GEOTECHNICAL SOLUTIONS. INC. & Consulting Geotechnical Engineers & Geologists 5931 Sea Lion Place, Suite 109 Carlsbad, California 92010 Office: 760-602-7815 smsgeoso1.incgmai1.com Project No. GI-16-06-128 July 25, 2016 Mr. Kyle Stephens Kyle Stephens & Associates 1350 Columbia Street, Suite 702 San Diego, California 92101 GEOTECHNICAL UPDATE REPORT, PROPOSED RESIDENTIAL DUPLEX DEVELOPMENT, EXISTING PAD (LOT 31), 4547 COVE DRIVE, CARLSBAD, CALIFORNIA Pursuant to your request, SMS Geotechnical Solutions, Inc. has completed the attached Geotechnical Update Report for the proposed single-family residential development at the above- referenced project property. The following report summarizes the results of our research and review of the previous pertinent geotechrncal reports, documents, and current grading plan, and provides update conclusions and amended recommendations for the proposed development, as understood. From a geotechnical engineering standpoint, it is our opinion that the property is considered substantially suitable for the planned residential development and associated improvements, provided our recommendations presented in this report are incorporated into the design and implemented during the construction phase of the project. The property is underlain by soft to loose saturated fills and lagoonal deposits, and special ground stabilization method(s) and foundation support system will be required for the planned development as presented herein. The conclusions and recommendations piovided in this study are consistent with the indicated site geotechnical conditions and are intended to aid in preparation of final construction plans and allow more accurate estimates of associate costs. If you have any questions or need clarification, please do not hesitate to contact this office. Reference to our Project No. GI-16-06-128 will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. Solutions, Inc. No. 23& Exp. 12/31/16 idi S. Shariat #2885 TABLE OF CONTENTS I. INTRODUCTION ......................................................I II. SITE DESCRIPTION ...................................................2 III. PROPOSED DEVELOPMENT ...........................................2 IV. SITE INVESTIGATION .................................................3 V. GEOTECHNICAL CONDITIONS .........................................3 Earth Materials .....................................................3 Groundwater and Surface Drainage ......................................4 Seismic Ground Motion Values ........................................4 Geologic Hazards ....................................................5 VI. FIELD AND LABORATORY TESTING ....................................9 VII. SITE CORROSION ASSESSMENT ......................................10 VIII. STORMWATER BMPs ................................................10 Bio-Rentention .......................................................10 Permeable Interlocking Concrete Payers (PICP) .........................11 IX. CONCLUSIONS .......................................................12 X. PROS AND CONS OF LIQUEFACTION MITIGATION ALTERNATIVES . . . .15 XI. RECOMMENDATIONS ................................................17 Ground Stabilization, Remedial Grading and Earthworks .................17 Post-Tensioned Rigid Raft Foundation Slab .............................28 Soil Design Parameters ..............................................30 B. Inter-Locking Payers ................................................31 XII. GENERAL RECOMMENDATIONS .....................................32 XIII. GEOTECHNICA.L ENGINEER OF RECORD (GER) ........................34 XIV. LIMITATIONS ........................... ............................34 c 4.. i TABLE OF CONTENTS (continued) FIGURES Geotechnical Map .............................................................1 GeologicCross-Sections ........................................................2 Fault-Epicenter Map ...........................................................3 TsunamiInundation Map ......................................................4 FEMAMap ................................................................5&6 Typical Bio-Retention Detail ......................................................7 TypicalPermeable Paver Detail .................................................8 Typical Ground Stabilization, N-S Direction ........................................9 Typical Ground Stabilization, E-W Direction ....................................10 Settlement Plate Schematic ......................................................11 Typical Foundation Plan .......................................................12 Typical Interior Stiffener Detail .................................................13 Typical Retaining Wall Back Drainage Detail ....................................14 ATTACHMENTS I & II Prior Geoteçhnical Reports by Vinje & Middleton Engineering, Inc. ATTACHMENT III USGS Seismic & Design Maps Summary Report GEOTECHNICAL UPDATE REPORT PROPOSED RESIDENTIAL DUPLEX DEVELOPMENT EXISTING PAD (LOT 31) 4547 COVE DRIVE CARLSBAD, CALIFORNIA I. INTRODUCTION The project property is an existing small bay-side lot adjacent to Agua Hedionda in the coastal areas of the 'City of Carlsbad. A Conceptual Grading Plan, prepared by Florez Engineering, Inc. is reproduced herein as Geotechnical Map, Figure 1. The approximate site location is depicted on a Vicinity Map included on Figure 1. The approximate site coordinates are 33.1457°N latitude and -1 17.3245°W longitude. We understand that the site is planned for the support of a duplex residential structure which will occupy much of the lot surface. The project property was the subject of prior detailed geotechnical studies performed by Vinje & Middleton Engineering, Inc. (VME) dating from 2004 to 2008 (initial boring explorations were completed in late 2003), completed in connection with a development very similar to the current development scheme shown on Figure 1. Their findings and development recommendations were provided in the following written technical report: "Drilled Caisson Foundations, Proposed LBC Condominium Project, 4547 Cove Drive, Carlsbad, California," prepared by Vinje & Middleton Engineering, Inc. Job #03-348-P, dated February 2008 (an unsigned draft copy was obtained and is included with this report as an Attachment I). "Foundation Plan Review, Proposed Three-Story Twin Homes, Lot 31, Tract 5162, Cove Drive, Carlsbad, California," prepared by Vinje & Middleton Engineering, Inc., December 13, 2006. "Update Geotechnical Report and Remedial Grading Ground Stabilization Recommendations, Lot 31, Tract 5162, Cove Drive, Carlsbad, California," prepared by Vinje & Middleton Engineering, Inc. Job #03-348-P, dated September 25, 2006 (included herein as Attachment II). "Foundation Plan Review, Proposed Three-Story Twin Homes, Lot 31, Tract 5162, Cove Drive, Carlsbad, California," prepared by Vinje & Middleton Engineering, Inc. Job #03-348- P, dated July 14, 2006 (included herein as Appendix A of Attachment II). "Preliminary Geotechnical Investigation, Lot 31, Tract 5162, Cove Drive, Carlsbad, California," Prepared by Vinje & Middleton Engineering, Inc. Job #03-348-P, dated March 3, 2004 (included herein as Appendix B of Attachment II). Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 2 6. "Addendum Geotechnical Report, Lot 31, Tract 5162, Cove Drive, Carlsbad, California," prepared byVinje & Middleton Engineering, Inc. Job #03-348-P, dated November 19,2003 (included as Appendix C of Attachment II, the printed date is suspected to be incorrect, and year 2004 is considered more reasonable for the actual report date). The referenced report is on file with our office and was reviewed in conjunction with this submittal. Selected references are attached to this report as Attachments I and II. The purpose of this effort was to update the referenced reports (Attachments I and II) and confirm their compatibility with the most current Grading Plan (Figure 1) with the indicated site geotechnical conditions. Revised and/or amended conclusions and recommendations consistent with the attached plan, current applicable codes and engineering standards are also provided in the following sections, and will supplement or superseded those given in the referenced report, where applicable. Our effort in connection with the preparation of this update report also included a recent site visit. However, added subsurface explorations, soil sampling, or laboratory testing were determined not necessary, and the prior work completed by the previous consultant in this regard was considered acceptable to us. Pertinent geotechnical data generated by the pervious consultant (see Attachments I and II) were also relied upon and utilized herein, where appropriate. SITE DESCRIPTION Site surface conditions are delineated on the attached Figure 1, and remain substantially unchanged from those described in the referenced report(s). In general, the project site is a small, roughly 40 feet wide by 117 long, nearly level lot between two developed residential buildings to the north and south. Cove Drive provides access and marks the front (western) boundary. A small rock-armored graded slope (shore protection rock revetments) marks the rear (eastern) boundary which descends approximately 10 feet into the adjacent lagoonal waters. The lot chiefly consists of dirt surfaces. Site drainage is indistinct with no evidence of scouring or runoff erosion. PROPOSED DEVELOPMENT The project development scheme is shown on Figure 1, and remains very similar to the prior development concept used a basis for the preparation of referenced reports by the prior consultant. As, shown, the project property is planned for the support of two narrow, connected side by side duplex-type residential development with associated improvements. The buildings will likely be two- story structures and will occupy much of the lot surface. Major grade alterations or creation of large graded slopes is not planned in connection with the project development with finish pad grades (13.15 feet MSL) established at or very near the existing ground surfaces. Project earthwork is expected to mainly consist of remedial grading ground stabilization operations. r Geotechnicai Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 3 Building construction and foundation designs are also not yet completed. Conventional wood-frame buildings with exterior stucco are anticipated. Several ground stabilization and foundation support options including utilizing deep drilled (CIP) caissons, driven piles, and mat and grade beam foundations with raised structural floor slabs were recommended by the prior consultant and still remain viable. However, we understand a structural rigid raft post-tensioned slab with perimeter and interior stiffening beam type foundation supported on stabilized bearing soils is also being considered due to site constrains and limitations, and based on relative ease of contraction, cost feasibility, and acceptable levels of risk and future building performance. SITE INVESTIGATION The original site investigation by Vinje & Middleton Engineering, Inc. (VME) included two exploratory test borings drilled with a truck-mounted rotary drill. Approximate location of exploratory test borings are shown on Figure 1. Logs of the test borings are included as Plates 5 and 6 of Appendix B in the enclosed Attachment II. Laboratory test data and engineering properties of underlying soils are also summarized in Appendix B (Pages 6 through 9) of Attachment II. GEOTECHNICAL CONDITIONS Geotechnical conditions at the project property remain largely as reported in detail in the referenced reports (see Attachment I). In general, the property consists of a nearly level graded pad apparently created in the 1960's as a part of the surrounding development by placing imported fill soil over natural lagoonal areas adjacent to Agua Hedionda. Depths of existing fills vary underneath each lot. Grading records for engineering observations and compaction testing of the existing fills are unavailable. A. Earth Materials Overall site subsurface conditions are described in the referenced reports. As established by the prior consultant, the project lot is underlain by a section of silty to clayey fill soils to a depth of nearly 15 feet that were placed atop natural lagoonal deposits. Formational siltstone rocks occur at an approximate depth of 49 feet below existing ground surfaces (BGS) underneath the lagoonal deposits. Added details of the site underlying earth materials are presented on the project exploratory boring logs (Plates 5 and 6, Appendix B of Attachment II) and further described in the referenced reports. Geologic Cross-Sections based on current topography and proposed finish grades are included as Figure 2. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 4 Groundwater and Surface Drainage Subsurface groundwater was encountered at depths of approximately 5 to 7 feet (B GS) at the time of original field explorations (August 2003). High groundwater levels are expected to be mostly on the order of 5 feet (BGS). The water reflects lagoonal water which has saturated the site underlying soils. The indicated levels are expected to fluctuate slightly with changing tide levels. Project over-excavations for ground stabilization and remedial grading operations are expected to encounter subsurface groundwater and light to heavy water intrusion into the excavations, depending on the seasonal and tidal conditions at the time of grading. Consequently, dewatering will likely be required and should be completed at each local quartered/phased rock mat placement and remedial grading sections, as specified below. Dewatering shall not be allowed to adversely impact the nearby buildings, structures and improvements. Completing grading during the dry seasons of .the year and low tidal conditions should be considered to minimize difficulties associated with dewatering operations. Some pre-dewatering may also be considered appropriate for this project. Any dewatering technique(s) suitable to the field conditions which can effectively remove the intruding water and allow soil removals and rock mat/fill placement is considered acceptable provided it is approved by the project engineer. Dewatering should continue until completion of remedial grading operations and should be discontinued only upon approval of the project geotechnical engineer. Groundwater should be lowered below the specified bottom of over-excavation, toe of temporary slope or trench excavations unless otherwise approved or directed in the field. As with all developed properties, the proper control of flood waters and site surface drainage is a critical component to overall stability of the graded building pad. Surface water should not pond upon graded surfaces, and irrigation water should not be excessive. Over-watering of site vegetation may also create perched water and the creation of excessively moist areas at finished pad surfaces and should be avoided. Seismic Ground Motion Values Seismic ground motion values were determined as part of this investigation in accordance with Chapter 16, Section 1613 of the 2013 California Building Code (CBC) and ASCE 7-10 Standard using the web-based United States Geological Survey (USGS) ground motion calculator. Generated results including the Mapped (Ss, Si), Risk-Targeted Maximum Considered Earthquake (MCER) adjusted for site Class effects (SMs, SMi) and Design (SDS, SDI) Spectral Acceleration Parameters as well as Site Coefficients (Fa, Fv) for short periods (0.20 second) and 1-second period, Site Class, Design and Risk-Targeted Maximum Considered Earthquake (MCER) Response Spectrums, Mapped Maximum Considered 4- Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 5 Geometric Mean (MCEG) Peak Ground Acceleration adjusted for Site Class effects (PGAM) and Seismic Design Category based on Risk Category and the severity of the design earthquake ground motion at the site are summarized in the enclosed Attachment III. D. Geologic Hazards Conditions which could result in potential geologic hazards are known in areas of San Diego County. The following geotechnical factors are evaluated herein: Seismicity I Faulting: A significant geotechnical factor which could impact the project site relates to ground shaking during an earthquake event along an active fault. Moderate to locally heavy levels of ground shaking can be anticipated during rare events over the lifetime of the development. The location of significant faults and earthquake events relative to the study site is depicted on a Fault - Epicenter Map enclosed herein as Figure 3. Faults or significant shear zones are not indicated within the project site. The project is not located in proximity to Alquist - Pnolo earthquake fault zone areas associated with active faults discussed above. Tsunami: A significant tsunami impacting the project property would be a very rare event. As indicated on a Tsunami Inundation Map for Emergency Planning (San Luis Rey Quadrangle), included herein as Figure 4, the project site is located on the tsunami inundation line. Consequently, potential tsunami risks are similar to the adjacent and nearby properties, and developments. Inhabitants of the residence should be aware of local evacuation routes as well as tsunami preparedness provided by the California Geological Survey on their web site. Flood Inundation: Lot 31 is located in lower hillside terrain along the west flank of lagoonal waters off of Agua Hedionda. Therefore, flooding hazards risks due to remote Tsunami inundation will require inhabitants' awareness and preparedness for such a rare condition. In order to further evaluate general site flooding potential, we obtained a pertinent copy of the available Flood Insurance Rate Map produced by the Federal Emergency Management Agency (FEMA). As shown on the attached FEMA map, the project property is located on panel 764 of 2375 with eastern margins on the line with Special Flood Hazard Areas Subject To Inundation By The I % Annual Change Flood, as depicted on the enclosed Figures 5 and 6. Flooding hazard risks for coastal flood zones with velocity hazards (wave action) will be similar to the adjacent and nearby properties and developments requiring inhabitants' awareness and preparedness for such a condition. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 6 4. Liquefaction and Seismically Induced Settlement: Liquefaction analyses were performed as a part of original site study performed by the previous consultant (VME report dated March 3, 2004, Appendix B of Attachment II). Their analysis (Page 5, Plates 8 and 9 of referenced report) concluded that "saturated site fills and natural lagoonal deposits are highly liquefiable (safety factors of less. than I)." Appropriate mitigation measures and foundation support system alternatives consistent with the site indicated geotechnical conditions were provided which included deep drilled (CIP) caissons or driven piles with raised structural floor slabs, and ground stabilization in conjunction with mat and grade beam foundations. Soil softeninj and liquefaction of the underlying deposits during a major seismic event along a nearby active fault remain the most.significant geotechnical concern at the project building site, and appropriate mitigation measure shall be implemented. As presented in the referenced reports, several mitigation alternatives are available. The choice of alternative will depend on site constraints and ease of construction, economic feasibility, and acceptable levels of risk and future building performance. Our research (USGS & OCOF) also indicates that projected sea level rise (SLR), estimated based on various climate scenarios for the next 75-years, may range from approximate average low of 2 feet (0.6m) to averagehigh of 4 feet (1.25m). Considering the finish pad grade elevation at roughly 13 feet (MSL), the projected SLR will not be a significant factor in our analysis nor influence our mitigation design recommendations. Impacts of future SLR will be similar to the adjacent and nearby properties, developments and public improvements requiring current and future owners' awareness and preparedness. Seismically induced total and differential settlements are accepted to be similar to the adjacent properties, nearby public improvements and existing surrounding developments, and may be estimated to be on the order of 13 and 6.5 inches for total and differential settlements respectively, for a rare 7.5 magnitude earthquake event. Smaller seismically induced total and differential settlements, on the order of 2 and 1 inch, respectively may be estimated for more frequent low magnitude seismic events. In the case of the rock mat ground stabilization option with remedial grading using reinforced 95% compacted fill, the recommended procedures are provided to alleviate differential settlements and limit total settlements to uniform conditions throughout the mitigated building pad areas. Design parameters for rigid raft post-tensioned type foundation support system is also provided to further withstand the approximate design estimates. However, the risk level of seismically induced total and differential settlements impacts after a major large magnitude seismic event requiring future mitigation measures will remain similar to the adjacent properties, neighborhood developments and nearby public improvements, and require awareness by the current and future homeowners. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 7 Lateral Spread: Lateral spread of the existing eastern rock-face slopes during an earthquake, event is also a major geotechnical concern. Liquefiable soils can create planes of weakness and sliding on the nearby graded slope posing a potential for failure. Details of the existing slope construction is not known, however, it was likely provided with a rock face to prevent erosion due to waive action and perhaps a filter layer and core materials to provide confinement and disallow large displacement due to lateral spread. Lateral spread of liquefied soils adjacent to the channel with breaks on ground surfaces creating blocks separated by fissures may be roughly estimated to be on the order of one foot. However, very large lateral spread is not expected under the liquefaction mitigated building pad surfaces, constructed as specified herein, with indicated minimum 15 feet building setback from the top of the rear channel slope. Houses and small buildings supported on deep CIP caissons/driven piles, or rigid raft post-tensioned type foundations are also expected to typically perform well with respect to potential lateral spread. The risk level of lateral spread outside the mitigated areas and possible future mitigation/repair measures will be similar to the adjacent properties and neighborhood developments and requires awareness by the current and future homeowners. Slope Stability: The rear slope is a continuous shore protection embankment feature extending well beyond the limits of the project property and is thought to have been created along the edge of the entire waterway as part of the original manmade cove and existing surrounding bayside developments. Disturbance of the rock-armored slope for investigative pUrposes, or by the planned development at the project property can result in costly mitigation and repairs, and in our opinion, shall be avoided. Details of the existing shore protection slope construction including thickness of the rock revetment, filter layer and core materials are not known. The man-made rock revetment-faced slope currently occurs at safe gradients ranging from 3:1 to 2:1 with the planned building adequately setback from the top of slope. The project portion of the slope is currently performing well with no indication of imminent or impending instability. In our opinion, detail slope stability analysis of the rear slope is not considered warranted, nor trenches or disturbance of the existing slope should be carried out to further confirm stability of the currently performing rear shore protection slope. Modeling of existing rear shore protection slopes with a rock armored face, which may include a filter layer and a core section, is also difficult and will include numerous uncertainties and redundant assumptions, which can result in misleading over or under estimation of the safety factor, and is not recommended by this office. The projected SLR will not be .a significant factor in slope stability with inside and outside slope groundwater levels expected to be very similar. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 8 The risk level of potential instability of rear slopes, which is a small portion of a continuous embankment feature extending well beyond the limits of the project property, and possible future mitigation/repair measures will be similar to the existing surrounding bayside developments and require awareness by the current and future homeowners. 7. Settlement: Settlement of foundation bearing soils is a geotechnical concern at the project construction site. Existing soft to very soft fills and lagoonal deposits will likely experience short and long term settlements. Treatment of upper sections of these deposits by means of removal and recompaction remedial grading will be necessary in order to construct more stable building surfaces for the support of the planned building and associated improvements, as recommended in the following sections. Rock mat stabilization method and reinforced earth compacted fill bearing soils are also recommended herein to alleviate very large differential settlements. Actual total and differential settlements will be measured by the installing geotechnical instrumentation devices (settlement plates) during the remedial grading efforts and surcharging the deeper lagoonal deposits with at least 5 feet of minimum 95% compacted fills. Monitoring is recommended here by means of field surveying shots periodically taken at each monitoring site as the backfill placement progresses, and continuing after completion of remedial grading. Data reduction and establishing settlement patterns and soil compression characteristics due to surcharge loading pressures byheavy construction equipment, compaction efforts, and earthwork activities are also recommended. Foundation trenching can only begin after data reduction and approval of the project geotechnical consultant (differential settlements on the order of 0.01 -foot or 0.12 inches between at least three consecutive post-grading readings per the monitoring schedule, unless otherwise noted or required by the project geotechnical consultant). The need for awaiting a period up to approximately 6 to 12 weeks after the completion of rough pad grading and before proceeding with utility and foundation trenching may be required for this purpose. Post-tensioned rigid raft type foundation option recommended herein is also specified for an allowable foundation pressure limited to 1000 psf. The specified foundation contact pressure is typically less than surcharge loading pressures induced by heavy construction equipments for achieving 95% compaction level within the fill mat. As a result, the majority of the expected total and differential settlements due to the anticipated foundation loads are expected to occur and recorded by the monitoring of the installed settlement. plates during the pad construction phase and specified monitoring period thereafter. However, secondary post construction settlement is expected to continue to occur after building construction. Total post-construction settlements may be anticipated to be uniform throughout the mitigated building pad areas and maybe roughly estimated to be & Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 9 on the order of approximately 2 inches. Large differential settlements are not anticipated and the magnitude of post construction differential settlements, as expressed in terms of angular distortion, may be estimated to be approximately on the order of 1-inch. Post- tensioned rigid raft type foundation slabs, as specified, should be designed to withstand the expected secondary total and differential settlements. The risk level of requiring related future mitigation is expected to be mostly similar to like construction types in neighborhood developments, and require awareness by the current and future homeowners. 8.. Collapsible Soils: Buildings and improvements founded on collapsible soils may be damaged by sudden and often large induced settlement when these soils are saturated after construction. Collapsible soils are typified by low values of dry unit weight and natural water content. The amount of settlement depends on the applied vertical stresses and the extent of the wetting and availability of water. Existing upper fill soils at the site may locally be prone to collapse potential and will require remedial grading mitigation as recommended herein. 9. Expansive Soils: Based upon our field observation, available laboratory testing, and experience with local soils, onsite shallow soils are expected to range from low to medium expansive. Clayey expansive bearing and subgrade soils are also considered a geotechnical concern at the project construction site. Adverse effects of the site potentially expansive clayey soils should be considered in the project designs and effective mitigation measures implemented during the construction of the project as specified in the fallowing sections. Utilizing good quality sandy (D .G.) import soils used to complete remedial grading and cap the building pad within the upper grades will help to mitigat&adverse effects of site expansive soils and enhance engineering properties of foundation bearing and subgrade soil. Saturated silty to clayey soils are also more difficult to process and achieve 95% compaction levels, and utilizing sandy granular (D.G.) import soils will increase remedial grading production levels. VI. FIELD AND LABORATORY TESTING Field and laboratory testing was performed by the previous consultant (VME) and presented in the referenced report dated March 3, 2004 (Appendix B of Attachment II). All field and laboratory testing provided in the referenced report is acceptable to us and were utilized herein, where applicable and as appropriate. 14. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 10 SITE CORROSION ASSESSMENT Based on results of available laboratory testing, close proximity of the site to saltwater and our experience with similar soils, the project site is considered highly corrosive. The amount of water soluble sulfate (SO4) was reported to be 0.268 percent by weight which is considered severe according to ACT 318 (S2 Exposure Class with Severe severity). Due to the expected concrete exposures to external seawater sources, chloride exposures should also be considered severe (C2 Exposure Class with Severe severity). Consequently, special high strength, Type V cement concrete with a minimum 28 days compressive strength (f) of 5,000 psi and a maximum water cement ratio of 0.40, as well as epoxy coated reinforcing steel (post-tensioning tendons) and greater reinforcement cover should be considered, as determined and confirmed by the project corrosion/structural engineer. A qualified corrosion engineer may be consulted in this regard. STORMWATER BMPs A. Bio-Retention An infiltration bio-retention basin is planned along the eastern property near the top of the eastern shore protection rock revetment slope. The top of the eastern armored shore protection slope will be disturbed or modified (removed) to accommodate the proposed bio- retention, as shown on Figure 1. Depth (thickness) of the bio-retention from adjacent pad grades and extent of top of slope disturbance or modification should be shown on the project plans. Details of the existing shore protection slope construction including thickness of rock revetthent, filter layer, and core materials are not known. The shore protection slope is a continuous feature extending well, beyond the limits of the project property and is thought to have been created along the edge of the entire waterway as part of the original manmade cove and existing surrounding bayside developments. Significant disturbance of the rock- armored slope by the planned development at the project property can result in costly mitigation and repairs, and should be avoided. The subsurface high groundwater table occurs at the anticipated depth of approximately 5 feet (BGS) and should be considered in the proposed bio-retention designs. Typically, a minimum 10 feet clear distance from bottom of infiltration bio-retention to high groundwater levels is required. In our opinion, the project property is not suitable for an infiltration bio- retention BMP considering the depth and potential groundwater level fluctuations. A self- contained system with an imperious liner on the sides and bottom and perforated underdrain pipe is recommended herein. The self-contained bio-retention facility may also be designed as a concrete containment structure with an adequately designed deepened edge along the building side to further enhance building pad stability against potential lateral spread along the top of the adjacent channel and disallow flotation (hydrostatic uplift pressure) in the Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 11 event of a sea level rise. The system should be properly sized for adequate storage capacity with filtrations completed not more than 72 hours. Vegetation, if incorporated into the designs, carefully managed to prevent creating mosquito and other vector habitats. A schematic concept of a self-contained bio-retention is shown on the attached Typical Bio- Retention Detail, Figure 7. Periodic inspections, upkeep, and continued maintenance of the project bio-retention BMP will be required to assure proper functioning and uninterrupted continuous discharge flow of the captured runoff water. Prolonged pondingof water in the proposed bio-retention can adversely impact the proposed new improvements and building performance, or potentially result in failures, and shall be avoided. In our opinion, a well-established maintenance program which includes careful management of bio-retention vegetation and testing for proper functioning of the underdrain/outlet pipes should be set in-place and followed by the current and future home owners. As a minimum, a maintenance schedule consisting of at least two times a year, before and after the annual rainy season, should be considered. In the event unfavorable conditions appear to be developing as noted during the scheduled maintenance program, appropriate repairs and mitigation should be carried out as necessary. B. Permeable Interlocking Concrete Payers (PICP) Permeable Interlocking Concrete Payers (PICP) in combination with the bio-retention are used as a part of the project stormwater quality treatment BMP, as shown on the attached Figure 1. Project stormwater BMP permeable interlocking payers should also consist of a self-contained filtration system. In general, PICP pavement structural section should consist of 31/a-inch, traffic rated PICP over a minimum of 2 inches of ASTM No. 8 bedding course/choke stone over a minimum 8 inches of ASTM No. 57 stone base course over a minimum of 12 inches of 95% compacted subgrade. A minimum 4-inch diameter perforated underdrain pipe (sch. 40 or greater) placed at suitable location for collection and disposal of infiltrated water through the CICP payers should also be provided in the ASTM No. 57 stone base course section. A schematic concept of a self-contained permeable paver section is shown on the attached Typical Permeable Paver Detail, Figure 8. Subgrade soils below the base course should be compacted to at least 95% compaction levels (per ASTM D- 1557). Bedding course/choke stone and base course stone should also be well compacted, consolidated and interlocked (avoid crushing the underdrain pipes) with heavy construction equipments. ASTM No. 8, No. 9 or No. 89 should be used for joint materials depending on the joint size and per manufacturer recommendations. Gradation requirements for ASTM No. 57, No. 8, No. 89 and No. 9 are as follows: Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 12 Sieve Size Percent Passing No. 57 No.8 I No. 89 No. 9 1V2" 100 1" 95to100 1/211 25 to 60 100 100 3/8 85 to 100 90 to 100 100 No.4 OtolO 10to30 20to55 85 to 100 No.8 0to5 O to' lO 5to30 10to40 No. 16 0to5 OtolO OtolO No. 50 0to5 OtoS IX. CONCLUSIONS Based on our review of the attached referenced reports (Attachments I and II), and our understanding of the project, development of Lot 31 for residential purposes is considered substantially feasible from a geotechnical viewpoint. However, the site is underlain by a section of soft to very soft saturated fills over thick saturated lagoonal deposits which will require special geotechnical engineering development techniques. Subsurface geotechnical conditions presented in the referenced reports remain unchanged, and all conclusions provided therein remain valid, unless otherwise amended and/or superseded below. The project site is not located within or near Aiquist - Priolo earthquake fault zone established by the State of California. The project property is located on the tsunami inundation line with potential tsunami risks similar to the adjacent and nearby properties and developments. Although a significant tsunami impacting the project property would be a very rare event, the current and future owners of the residence should be aware of local evacuation routes as well as tsunami preparedness provided by the California Geological Survey on their web site. The eastern margins of the project property are also located on the line with Special Flood Hazard Areas Subject To Inundation By The I % Annual Change Flood, as designated by FEMA Flood Insurance Rate Map. Flooding hazards risks for coastal flood zones with velocity hazards (wave action) at the project site will be a very rare event and similar to the adjacent and nearby properties and developments, requiring awareness and, preparedness by the current and future.owners of the residence. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 13 Liquefaction and soil softening of the underlying deposits during a major seismic event along a nearby active fault are considered the most significant geotechnical concern at the project building site. Secondary effects such as ground spreading and lurching, and large seismically induced settlements are also a major concern at the study site. Ground stabilization techniques and special foundation designs will be required for the support of proposed building to withstand seismically induced vertical and lateral ground displacements to reasonably acceptable risk levels, and construct improved pad surfaces. Several ground stabilization methods and foundation options are available to alleviate impacts of liquefaction and potential loss of strengths of the underlying liquefiable soils. In general, the most effective design method includes utilizing deep foundations which penetrate the liquefiable soils and are supported into the formational bearing strata below. Other alternatives are also available and may be considered depending on economic feasibility, ease of construction and the acceptable risk level. Most commonly used mitigation alternatives and techniques available for the project site, as well as pros and cons of each alternative are briefly discussed below. Potential impacts of lateral spread of the existing eastern rock-face slope on the proposed new building during an earthquake event is also a major geotechnical concern. In order to alleviate potential impacts of ground displacement due to lateral speared of the eastern slope, adequate building and improvement setback from the top of slope shall be maintained, and special building foundations design(s) as well as stabilized reinforced compacted fill mat under the site improvement will be required for achieving a reasonably acceptable risk level and tolerances, as specified in the following sections. The existing slope shall not be. impacted, disturbed or modified by the planned constructions and proposed new building development with related ground stabilization and construction works maintaining adequate set backs from the top of slope, as specified in this report. The underlying soft clayey fills and lagoonal deposits are highly compressible. The most effective design method to mitigate impacts of large settlements in case of very thick compressible, saturated clays, is utilizing deep foundations which penetrate the unsuitable soils and are supported into the formational bearing strata below. Other options such as shallow ground stabilization and surcharging with compacted fill overburden are also commonly used to create uniform post-construction total settlement throughout the mitigated building pad areas, and limit differential settlements, considering acceptable risk levels. For this purpose, higher levels of fill compaction (minimum 95%) and installations of settlement plates placed at the bottom of the over-excavations will be required to monitor settlement of the surcharged lagoonal deposits, as specified in the following sections. LI Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 14 The project site is an existing nearly level graded lot and significant grade alterations or construction of new large grade slopes is not anticipated. Earthwork operations necessary in connection with the planned development will chiefly consist of remedial grading and ground stabilization work. Groundwater was encountered in both exploratory boring excavations drilled in 2003 at the depths of approximately 5 to 7'/2 feet (BGS) below the surface. High groundwater conditions are expected to be at about 5 feet (BGS) at the project site and expected to fluctuate with tidal conditions. Dewatering will likely be required in case of rock mat stabilization and remedial grading options, and should be completed at each local quartered/phased remedial grading section, as specified below. Dewatering should lower the groundwater levels below the bottom of excavation and should continue as rock mat and fill placement progresses. Dewatering shall not be allowed to adversely impact the nearby buildings, structures and improvements. Completing grading during the dry seasons of the year and low tidal conditions should be considered to minimize difficulties associated with dewatering operations. Some pre-dewatering may also be considered appropriate for this project. Site excavations and earthwork shall not impact the adjacent properties, structures, improvements, and underground utilities within public right-of-ways. Initially, attempts may be made to complete ground stabilization by remedial grading in local quartered/phased sections with 1: 1 laid back construction slopes. However, excavation shoring consisting (drilled concrete piles reinforced with steel beams with wood lagging) should be anticipated and will be required for developing a safe excavation and protect the adjacent building foundations, structures and improvements, as recommended below. Shoring designs are provided in the following sections. Earth materials generated from the site excavations, stripping, removals and over- excavations will chiefly consist of marginal quality, wet to saturated plastic silty to clayey deposits. All site organic soils, deleterious matter and unsuitable materials encountered during the excavations, stripping, removals and over-excavations should be properly removed and exported from the site using select grading techniques. Good quality sandy granular (I).G.) import soils should then be used as site new fills and backfllls to complete grading and achieve final design grades. Based on select grading recommendations specified herein, final bearing soils are expected to chiefly consist of silty sand (SM/SW) deposits with very low expansion potential (expansion index less than 20) based on ASTM D-4829 classification. Consequently, expansive soils will not be a factor in the project development. However, the rigid raft post- tentioned foundation support system, if considered, should be designed for the minimum specified center lift and edge lift differential swells provided in the following sections. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 15 X. PROS AND CONS OF LIQUEFACTION MITIGATION ALTERNATIVES Special foundation designs and ground stabilization techniques will be required to improve site stability against potential liquefaction, soil softening, lateral spread, ground displacement and settlements, and enhance building performance. Several ground stabilization methods and building/foundation support options are available. The choice of alternative will depend on economic feasibility, ease of construction, acceptable risk levels and future building performance. A few of the most common techniques, in our opinion, suitable to the project property are briefly discussed below: Option (i) Driven concrete piles with grade beams and structural floor foundations were recommended by the previous consultant (VME report dated March 3, 2004, Appendix B of Attachment II). This method is still a viable option from our standpoint, and may be considered. Specific design parameters are given in the referenced report and remain valid. In this case, 15 inches square prestressed concrete piles adequately driven to competent bearing strata, until allowable design pile capacity is developed will be required. This method will require large pile driving equipments, may be more difficult to carry out due to site constraints, generate vibrations that can be damaging to the very closely located neighboring buildings, and could also be very costly. A speciality contractor(s) is required to complete this work. Option (ii) Cast-In-Place (CIP) concrete piles with grade beams and structural floor foundations were also recommended by the previous consultant (\TME report letter dated February 27, 2008, Attachment I). This method is still a viable option from our, point of view, and may be considered. Specific design parameters are given in the referenced letter and remain valid. In this case, 2-feet-71 0 inches diameter C1P piles, drilled to a minimum depth of 57.5 feet (BGS) will be required. This method will require large equipment for pile shaft drilling below the water table to the required depth, potential pile shaft caving and appropriate stabilization, handling of large amounts of spoil soils generated from shaft drilling, steel cage fabrication, placement and splicing, and concrete pour in a tight construction area that could be very costly. A speciality contractor(s) is required to complete this work. Option (iii) Compaction (pressure) grouting of lagoonal deposits and remedial grading of the foundation bearing soils with stiff grade beam footings and structural slab-on-ground mat type foundations. For this purpose, compaction grouting will be used to densify site liquefiable/soft soils from the depth of nearly 49 feet to approximately 3 feet below the final pad grade. The upper 3 feet will then be removed and recompacted using conventional remedial grading techniques. Compaction (pressure) grouting may adversely impact nearby shore protection slope, adjacent neighboring buildings, improvements and underground utilities, and could be very costly. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 16 Hardening (mixing) techniques by introducing grout materials through permeation, mixing may also be considered for treatment of soft fills and lagoonal soils. In this case, in-situ conformation testing of the treated soils by performing SPT sampling (ASTM D- 1586) will be required to verify adequate densification within the treated deposits. A speciality contractor(s) is required to complete this work. Option (iv) Vibro-replacement (vibro-stone column) with a rock mat and compacted soils in the foundation zone, in combination with grade beam footings and structural slab-on- ground mat type foundations may also be considered. In this case, a vibroprobe penetrates to a minimum depth of 49 feet by vibration and jetting of air. Gravels are then added through a tremie pipe alongside the vibroprobe to create a stone column. A rock mat is then placed over the top of the installed stone columns at about 3 feet below the final pad grades. Finally, compacted soils will be used in the foundation zone and achieving pad grads. This method utilizes large equipment, generating driving vibrations potentially impacting the very closely located neighboring buildings and could be very costly. A speciality contractor(s) is required to complete this work. Option (v) Rock mat stabilization with remedial grading using reinforced, 95% compacted fill, in combination with grade beam and structural mat type foundation were also recommended by the previous consultant (VME report dated November 19, 2003, Appendix C of Attachment II). This method is still a viable option, and may be considered. Rigid raft post-tensioned type foundations with perimeter grade beams and interior stiffening beams can also be considered in lieu of mat foundations. In this case, the upper bearing soils are removed and bottom of excavation stabilized with a rock mat, with groundwater level lowered below the bottom of excavation. Upon achieving stable bottom conditions, compacted fills using reinforced earth will be placed to achieve pad grades. Excavation shoring along the north and south margins adjacent to the neighboring building foundations will likely be required to complete this technique. Geotechnical instrumentation and settlement monitoring will also be required for this method to record behavior of the compacted reinforced fill mat support prior to utility and foundation trenching. This option, however, is similar to conventional remedial grading techniques, and with the exception of the excavation shoring, a speciality contractor(s) is not required to complete the work. Relative ease of the contraction method (compare to the other available techniques), site suitability with respect to existing constrains and access limitations, and construction costs feasibility are considered the "pro" attributes of this option. However, although this option is generally expected to alleviate major geotechnical concerns within reasonable risk levels, it is not considered in the same Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 17 higher mitigation level ("cons") as some of the other options, such as vibro- replacement (vibro-stone column), and driven or drilled CIP pile foundations alternatives. The property owner(s) should carefully evaluate the pros and cons, and cost-benefit aspects of each alternative for choosing a specific mitigation technique, with the selection of a desired alternative and mitigation procedure passed on to the future homeowner(s). The final choice of an option will depend on site limitations, acceptable levels of risk, and building performance, economic feasibility and ease of construction. Specific recommendations and design parameters for prestressed driven and drilled CIP concrete piles with grade beams and structural floor foundations, provided in the referenced reports(VME reports, Attachments I and II) are acceptable to us and remain unchanged. Rock stabilization with remedial grading, and mat and grade beam foundations (Option "V") were also provided in the referenced reports(VME reports, Appendix C of Attachment II) and are also generally acceptable to us, except where specifically amended to superseded below. It should be noted, however, that in some cases, site conditions developed during excavations for rock stabilization and remedial grading work, such as excessive uncontrollable groundwater intrusions, large bottom of excavation heaving (boiling), large caving and undermining or impacting adjacent buildings and improvements may not allow implementing Option V, as determined in the field, requiring selection of an alternative method as determined at that time, and cannot be ruled out. Specific recommendations for any other options can be provided upon request. XI. RECOMMENDATIONS All recommendations provided in the referenced reports (Attachments I and II) remain valid and should be considered in the final designs and implemented during the construction-phase, where appropriate and as applicable. The following modified rock stabilization with remedial grading in combination with rigid raft post-tensioned type foundations with perimeter grade beams and interior stiffening beams recommendations (Option "V"), however, will supersede those given in the referenced reports and should be considered in final designs and implemented during the construction phase: A. Ground Stabilization, Remedial Grading and Earthworks The project property is underlain by a relatively modest section of soft clayey fills over thick lagoonal soil deposits. As discussed herein, a more conventional method, generally expected to alleviate major geotechnical concerns within reasonable risk levels, consists of removal and recompaction ofupper soils, and surcharging the underlying untreated soils using special remedial grading ground stabilization techniques. Remedial grading ground stabilization of the upper foundation soils should construct safe and stable building surfaces as specified herein. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 18 Recommended remedial grading concept and associated earthworks details are schematically illustrated on the enclosed Typical Ground Stabilization, N-S Direction and Typical Ground Stabilization, E-W Direction, Figures 9 and 10 respectively. All excavations, grading, earthworks, constructions and bearing soil preparations should be completed in accordance with Chapter 18 (Soils and Foundations) and Appendix "J" (Grading) of the 2013 California Building Code (CBC), the Standard Specifications for Public Works Construction, City of Carlsbad Grading Ordinances, the requirements of the governing agencies and following sections, wherever appropriate and as applicable: Underground and Utility MarkOuts: All existing underground waterlines, sewer lines, storm drains, utilities, tanks, structures and improvements at or nearby the project construction site should be throughly potholed, identified and marked prior to the initiation of actual ground stabilization works, excavations, remedial grading operations, trenching and earthworks. Specific geotechnical engineering recommendations may be required based on the actual field locations and invert elevations, backfill conditions and proposed grades in the event of a grading conflict. Utility lines maybe needed to be temporarily redirected, if necessary, prior to earthwork operations, and reinstalled upon completion of the constructions. Alternatively, permanent relocations may be appropriate as shown on the approved plans. Abandoned lines, irrigation pipes and conduits should be properly removed, capped or sealed off to prevent any potential for future water infiltrations into the site fllls/backfills, foundation bearing and subgrade soils. Voids created by the removals of the abandoned underground pipes, tanks and structures should be properly backflhled with compacted fills in accordance with the requirements of this report. Site Preparation and Clearing: Remove existing surface improvements, vegetation and other unsuitable/deleterious materials from all areas of the planned new structure and improvements plus 3 horizontal feet minimum outside the perimeter where possible, and as directed in the field. Vegetation, debris, grasses, trees, roots, stumps, and other deleterious or unsuitable materials should be thoroughly removed and cleared from the construction site to the satisfaction ofthe project geotechnical consultant. Debris and site vegetation should not be allowed to occur or contaminate new fills and backfills. The prepared ground should be inspected and approved by the project geotechnical engineer or his designated representative. Removals and Over-Excavations: Site upper soft and compressible soils in the building envelope areas plus a minimum of 3 feet in the north/south ends and 5 feet along at the east-west ends, outside the perimeter and as directed in the field, should be removed to a minimum uniform depth of 6 feet below the existing grades (BGS) or at Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 19 least 4 feet below the bottom deepest footing(s), whichever is more (also see Typical Ground stabilization Figures 9 and 10). In the front paving improvement areas plus• minimum 18 inches outside the perimeter, where possible and as directed in the field, removal depths should extend a minimum of 2.5 feet below the existing grades or a minimum of 12 inches below the bottom of deepest utility, whichever is more. Locally, deeper removals may be necessary based on the actual fied exposures and should be anticipated. Actual depths should be established by the project geotechnical engineer at the time of ground stabilization work and remedial grading operations. 4. Excavations, Temporary Construction Slopes and Shoring: Excavation shoring consisting of drilled concrete piles reinforced with steel beams and wood lagging will most likely be required fordeveloping a safe excavation and protect the adjacent building foundations, structures and improvements, as recommended below. However, initially attempts may be made to complete removals/over-excavation, bottom stabilization and pad reconstruction to rough finish grades with compacted fills in limited quartered/phase sections as delineated in the enclosed Geotechnical Map, Figure 1. * Attempting Temporary Construction Slopes: Preliminary excavation setbacks and temporary construction slope development concept are depicted on the enclosed Figures 9 and 10. In general site geotechnical conditions are not favorable for temporary laid back construction slopes. However, initially attempts may be made to develop laid back excavations only in limited quartered sections not exceeding approximately one-fourth of total length of the project ground stabilization areas. Developed temporary construction slopes shall maintain the required set backs and initially laid back at 1:1 gradient maximum, unless otherwise noted or directed. A limited section of 1:1 of the temporary slope can then be cut at near vertical condition within the excavation areas, if the exposed section is immediately backfilled with stabilization rocks and compacted fills in a same day operation, with the groundwater lowered below the bottom of excavations. Vertical excavation left exposed over- night or for an extended period of time shall not be allowed. Any suspected or potential unfavorable exposures and excavation stability conditions (such as caving and/or development of tension cracks along the top of excavation), as determined in the field, shall result in abandoning this procedure and implementing shoring support, as discussed below. Monitoring of site excavations and adjacent buildings are also recommended herein (see following sections). In the event construction works requires prolonged (overnight) temporary slope exposures, or field observations and monitoring indicates a potential for failure and possible movements causing damage to the neighboring building, shoring protection of nearby structures shall be required. Any continuous shoring technique which can allow safe and stable excavations, and Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 20 protect adjacent buildings, properties and nearby structures and improvements may be considered. A qualified design/build shoring contractor should be consulted in this regard. * Excavation Shoring Support: Anticipated. prolonged unsupported excavation exposures during construction, excavations resulting in steeper than 1:1 maximum gradients, excessive groundwater intrusions or excessive deflections/deformations (greater than 1-inch) of site excavations, and monitoring results of adjacent buildings will necessitate installation of excavation shoring support, and most likely be required and should be anticipated. Shoring will also allow development of larger excavations, thereby increasing production levels, however, due to site constraints and groundwater intrusions, excavations larger than one-half of the total length of the project ground stabilization areas are not recommended. Approximate locations requiring excavation shoring are delineated in the enclosed Geotechnical Map, Figure 1. Typical Excavation Shoring detail is shown on Figure 9. In general, any temporary continuous shoring system which can adequately support adjacent building foundations, underground utilities and nearby improvements along the northern and southern property margins (see Figure 1), and provide safe and stable excavation conditions may be considered. An effective temporary shoring support suitable to the site subsurface conditions may consist of drilled reinforced cast-in-place (CIP) concrete piles with wood lagging system (Figure 9). Any other shoring system, if considered, should be reviewed and approved by the project geotechnical consultant. The following soil design parameters are appropriate for shoring design: - Design point of fixity should be assumed 2 feet below the specified bottom of over-excavations. - Design maximum deflection should be limited to 1-inch unless otherwise noted or approved. Protection of existing buildings, foundations, pipes, utilities, conduits, and underground improvements and nearby structures located within the zone of influence of planned vertical excavation is one of the most important criteria in determining a shoring support system and shall be considered in the project designs and constructions. The shoring wall system stiffliess, and sequence of excavations shall limit horizontal and vertical deflections within allowable tolerances. The project shoring contractor should evaluate the structural capacity of existing nearby foundations, buildings, pipes, utilities, conduits and underground structures and determine the allowable acceptable tolerances for his considerations in implementing in a given shoring system. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 21 - Shoring piles should be at least 24 inches in diameter. Maximum pile spacing should be not exceed 8 feet. - A design apparent lateral soil pressure of 40 pcf (EFP, for heights above the water table) may be considered for temporary shoring conditions. A design apparent buoyant lateral soil pressure of 22 pcf (EFP), in combination with a 62 pcf (EFP) hydrostatic pressure, should be considered for temporary shoring conditions below water tables. Water table is recommended herein to be lowered below the bottom of excavations with dewatering efforts. An additional 640 lbs.Ift. resultant lateral force acting at the depth of 2.9 feet (BGS) caused by surcharge loading of nearby building foundations should also be considered for temporary shoring design, unless otherwise determined by the project design/build consultant. Design apparent passive resistance of 200 psf/fi maybe considered for temporary shoring for the portion embedded below the point of fixity. The passive resistance may be increased by the indicated value for each additional foot of depth to a maximum 3000 pounds per square feet. - Additional soil design parameters are provided in the following sections of this report. * General Excavation Requirements: Top of excavations and temporary slopes shall maintain adequate set backs from adjacent neighboring buildings, existing on and offsite improvements and structures as approved and directed in the field. Undermining and/or damages to adjacent buildings, existing improvements, structures, underground utilities and within public right-of-way or adjacent easements and properties shall be avoided. Face of temporary slopes should be protected from excessive runoff or rainfall and stockpiling the excavated materials near the top of construction embankments should be disallowed. Construction should be also completed in a timely manner minimizing unsupported slope conditions for prolonged period of time. Bottom of over-excavations will be approximately 12 inches below the anticipated high groundwater levels and moderate to heavy groundwater intrusions into the site excavations should be expected. Groundwater should be lowered to below the bottom of excavations using dewatering techniques. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California . Page 22 Site excavations and temporary shoring support will require continuous geotechnical observation during the earthwork operations. Additional recommendations should be given by the project geotechnical consultant at that time as necessary, based on actual field exposures.. The project contractor should also obtain appropriate excavation permits, as needed, and conform to the Cal-OSHA and local governing agencies' requirements for open cut and trenching excavations, and safety of the workmen during construction. Commencing site excavations may also require obtaining permits from the adjacent property owners or public agencies, as appropriate and applicable. 5. Excavation Monitoring and Adjacent Neighboring Buildings: Monitoring of the site excavations and adjacent neighboring buildings will be required during the ground stabilization work and pad reconstruction phase. For this purpose, an appropriate excavation monitoring program should be incorporated into the project plans and implemented during site construction. We recommend an excavation monitoring program which include the following: * Pre-construction conditions of all existing nearby buildings, structures, improvements and utilities within 100 feet minimum from the top of excavation or twice the excavation depth, whichever is more, should be well documented and recorded (photographed and video taped). * Elevations and horizontal position of all existing nearby buildings, structures, improvements and utilities within 100 feet minimum from the top of excavation (or twice the excavation depth, whichever is more) should be established prior to initiation of actual excavation works. Survey and monitoring points should be established on the nearby buildings, structures, improvements and utilities at intervals less than 25 feet maximum and identified on the project grading or a separate Monitoring Plan. Monitoring data should be recorded to 0.01-foot accuracy. * Bench marks and reference locations for the survey and monitoring points should be established outside the influence zone of the excavations and construction equipment vibrations (minimum 100 feet or at least twice the excavation depths, whichever is more) as shown on the project grading or Monitoring Plan. * Record elevations and horizontal position of each survey and monitoring point before and after any major event, phased excavation, changes in excavation exposures (such as development of ground cracks near top of excavations or side caving), and any suspected or observed movements, as well as change in geologic units and unexpected groundwater impacts. Survey weekly during shoring, excavations, and backfilling activities. Survey at least on a monthly basis thereafter until terminated by the project geotechnical consultant. Q Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 23 * Data generated from the monitoring program may establish new conditions requiring reconsideration into the temporary slope and shoring designs resulting in field revisions including but not limited to smaller excavation exposures or installations of additional or an intermediate shoring support system. 6. Ground/Bottom of Over-Excavation Rock Stabilization: Bottom of removals/over- excavations at the specified depth is anticipated to expose very soft to soft yielding conditions overall not suitable for receiving new fills or backfllls. Consequently, a stabilization rock mat will be required and should be placed over the exposed bottom of excavation, as conceptually depicted on the enclosed Typical Ground stabilization, Figures 9 and 10. The stabilization rock mat should initially consist of placing one-foot minus crushed angular rocks over the entire bottom of over-excavations and tracking the rocks with heavy construction equipment as directed in the field. Rock placement and tracking should continue until soft to loose soils at the bottom of removals are sufficiently displaced and rocks are fully interlocked achieving a non-yielding condition as determined in the field. Dewatering shall be carried out, as specified herein, to remove the intruding and displaced water and accelerate the bottom stabilization work. Subsequently, an approximate 6-inch thick layer of 11/2 to %-inch crushed rocks should be placed over the larger rocks at the bottom and then tracked with heavy construction equipment to adequately in-fill larger rocks, enhance interlocking and provide a stable surface non-yielding conditions suitable for receiving fill. A layer of Mirafi 500X (or greater from the same series or approved equal) soil separation geotextile should then be provided neatly placed over the top of the rock mat as directed in the field. Placement of reinforced fill and backfilling can then proceed until final pad grades are achieved. The actual rock mat thickness needed to achieve an unyielding bottom will depend on the in-place characteristics of the site exposures at the time of grading. Variables which will influence the rock mat thickness include specific engineering properties of the underlying soil conditions at the exposed over-excavation depths and the type of the heavy equipment used to track-walk the rock. Based on our experience with similar projects, a consolidated rock thickness on the order of 3 feet will be required. Added recommendations and field modifications for the stabilization rock mat including larger or a thicker rock section may be required depending on the site and groundwater conditions at the time of constructions and should be anticipated. Dewatering and lowering of groundwater (removal of displaced water) below the bottom of over- excavation shall be continued during rock mat and subsequent fill placement. Geotechnicat Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 24 In the on-grade improvement areas outside the building envelop only, such as driveways, a rock mat may be not necessary as determined in the field. However, fills can only be placed upon non-yielding bottom of over-excavations as determined by the project geotechnical engineer or his designatçd field representative. A minimum removal depth of 2.5 feet below finis pad grades or 12 inches below the bottom of deepest utility, whichever is more, is considered adequate in these areas unless otherwise noted. However, due to the expected unsuitable and yielding bottom of removals, a layer of TerraGrid RX-1200 (or greater) stabilization geogrid earth reinforcement should be neatly placed over the exposed surfaces prior to backfihling as directed in the field. Groundwater and Dewatering: High groundwater is expected at the depth of approximately 5 feet (BGS), subject to fluctuation with tidal conditions. Dewatering and removal of intruding/displaced water will be required for successful completion of site stabilization, rock mat placement, allowing remedial grading operations to progress. Dewatering should be completed at each local quartered/phased remedial grading section, with groundwater levels lowered below the bottom of excavation and should continue as rock mat and fill placement progresses. Any dewatering technique which can effectively remove the intruding/displaced water and lower the groundwater below the bottom of excavation may be considered. Sump and pump method consisting of an excavation of a two-foot deep hole backfilled with 3A- inch crushed rocks at a low point in the over-excavated areas to act as a sump, and dewatering using a submersible pump is usually a common procedure. More specific recommendations should be provided by the project geotechnical consultant at the time of trenching and excavation inspections based on actual field exposure. Dewatering shall not be allowed to adversely impact the nearby buildings, structures and improvements. Completing grading during the dry seasons of the year and low tidal conditions should be considered to minimize difficulties associated with dewatering operations. Some pre-dewatering may also be considered appropriate for this project to facilitate excavations and ground stabilization work. Underdrain: A subsurface underdrain system consisting of a minimum 6-inch diameter perforated pipe (SDR 35) surrounded with crushed rocks (%-inch) and wrapped in filter fabric (Mirafi 140 N) installed within the I Y2"-Y4 crushed rock layer may be required as determined and directed in the field. The need for a subsurface underdrain will most depend on conditions of site excavations, rock stabilization performance under track walking and groundwater intrusions. Actual underdrain construction details should be provided by the project geotechnical engineer, if it becomes necessary. The underdrãin should be installed at suitable elevations above the "historic high tides" sea level to provide minimum 2% fall via a non-perforated out on eastern rock face slope, or other approved discharge location. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 25 9. Fill Materials and Import Soils: In general, soils generated from the site excavations will chiefly consist of marginal to very poor quality, plastic, wet to saturated silty to clayey deposits. Generated deposits are not suitable for reuse as site new fills and backfills, and should be removed and exported from the site. Good quality sandy granular (D.G.) soils should then be imported and used as new fills and backfills for completing remedial grading and achieving final pad grades. Import soils should consist of very low expansive non-corrosive sandy (D.G.) granular deposits (100% passing 1- inch sieve, more than 50% passing #4 sieve and less than 18% passing #200 sieve with expansion index less than 20) tested and approved by the project geotechnical engineer prior to delivery to the site. Import soils should also meet or exceed the engineering properties of site soils as specified in the following sections. BackfillinglReinforced Fill Mat: Upon completion of stabilization rock mat placement and approval of the project geotechnical consultant, building pad reconstruction to design finish grade with reinforced compacted import fills can begin. An initial fill lift on the order of 6 to 8 inches thick should be carefully and neatly placed atop the Mirafi 500X soil separation geotextile and compacted as specified herein. A layer of TerraGrid RX- 1200 (or greater) earth reinforcement geogrid should then be placed over the initial fill lift, followed by the second fill lift also on the order of 6 to 8 inches thick compacted as specified herein. Settlement plates can then be installed in accordance with requirements of this report. Backfihling and compaction should subsequently proceed with a second layer of TerraGrid RX-1200 (or greater) placed within the compacted fill mass approximately 12 below the bottom of deepest footing(s) or a minimum of 6 inches below the deepest underground utility and plumbing trenches, unless otherwise approved. Details of a reinforced compacted fill mat are conceptually shown on the enclosed Figures 9 and 10. A minimum of 18 inches overlap should be considered for Mirafi 500X soil separation geotextile and TerraGrid RX.-1200 earth reinforcement geogrid when completing remedial grading is limited quartered/phased sections. Uniform and stable well-compacted fill mat support should be constructed underneath the proposed building pad areas by the earthwork operations. For this purpose, site new fills and backfills should be adequately processed, thoroughly mixed, moisture conditioned to slightly (2%) above the optimum moisture levels, placed in thin (6 to 8 inches maximum) uniform horizontal lifts and mechanically compacted to a minimum of 95% of the corresponding laboratory maximum dry density per ASTM D-1557. Minimum 95% compaction levels shall be required for all site fills and backfills including, storm drains, utility and plumbing trench backfills, unless otherwise approved or directed in the field by the project geotechnical consultant. Instrumentations and Settlement Monitoring: Geotechnical instrumentation devices consisting of two settlement plates should be installed at the project building site, as schematically shown on the enclosed Typical Ground Stabilization Figures 9 and 10. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 26 Settlement plates should be placed near the bottom of the over-excavations, at selected locations not to interfere with the project grading and post grading construction phases, in order to monitor settlement of the underlying surcharged natural lagoonal deposits. Preliminary locations of settlement plates are shown on the attached Geotechnical Map, Figure 1. A typical detail and installation concept of a settlement plate are shown on the enclosed Settlement Plate Schematic, Figure 11. Geotechnical instrumentation should be installed by or under direct supervision of the project geotechnical consultant. Monitoring should be performed by means of field surveying shots periodically taken at each monitoring site as the fill and backfill placement progresses approximately once every two to three days, unless otherwise approved. At the completion of remedial grading, monitoring should continue on a biweekly and/or monthly basis, per the monitoring schedule developed by the project geotechnical consultant. Monitoring should be carried out by surveying methods provided by the project civil engineer/surveyor or contractor. Survey records (vertical and horizontal positioning) should then be reduced by the project surveying consultant soon after field measurements and provided to the project geotechnical consultant to establish settlement patterns and soil compression characteristics with respect to surcharge loading pressures, compaction efforts and earthwork activities (vertical deflection versus time plot). Foundation trenching can only begin after data reduction and approval of the project geotechnical consultant (0.01-foot or 0.12 inch differential between at least three consecutive post-grading readings per the monitoring schedule, unless otherwise noted or required by the project geotechnical consultant). A waiting period between 6 to 12 weeks may be anticipated after the completion of rough pad grading to proceeded with foundation trenching and constructions. Foundation recommendations provided in the following sections should be also confirmed and / or revised based upon the settlement monitoring data compiled at the completion of monitoring period, as necessary and appropriate. 12 Surface Drainage and Erosion Control: A critical element to the continued stability of the graded building pads is an adequate storm water and surface drainage control. This can most effectively be achieved by appropriate storm water control and drainage structures, vegetation cover and the installation of the following systems: * Flooding, soil erosion, scouring and sediment transport should not be allowed at the site. Erosion prevention facilities as well as flooding and runoff control drainage structures should be installed and constructed as shown on the approved drawings. * Concentrated flow should not be allowed. Lined concrete drainage facilities should be considered for directing stormwater and surface runoff to appropriate discharge facilities. Geotechuical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 27 * Building pad and improvement surface runoff should be collected and directed away from the planned buildings and improvements to a selected location in a controlled manner. Area drains should be installed. * Temporary erosion control facilities and silt fences should be installed during the construction phase periods and until landscaping is established as indicated and specified on the approved project grading or erosion control plans. 13. Engineering Observations and Testing: All ground stabilization work, remedial grading and earthwork operations including excavations and removals, dewatering efforts, shoring procedures and temporary excavation slopes, rock and earth reinforcement geogrid placement, instrumentation, suitability of import soils used as site new compacted fills and backfllls, fill/backfill placement and compaction procedures should be continuously observed and tested by the project geotechnical consultant and presented in the final as-graded compaction report. The nature of finished bearing and subgrade soils should be confirmed in the final compaction report at the completion of grading. Geotechnical engineering observations should include but are not limited to the following: * Initial observation - After clearing limits have been staked but before ground stabilization and remedial grading starts. * Shoring/excavation observation -During shoring installations and site excavation but before the vertical depth of excavation is more than 3 feet. Local and Cal-OSHA safety requirements for open excavations apply. * Removals, dewatering and bottom of over-excavation observation - After removals/over-excavations to the specified depths and installation of dewatering facilities, but before placing stabilization rocks are placed. * Fill/backfill observation - After the fill/backfill placement is started but before the vertical height of fill/backfill exceeds 2 feet. A minimum of one test shall be required for each 100 lineal feet maximum in every 2 feet vertical gain, with the exception of wall backflhls where a minimum of one test shall be required for each 30 lineal feet maximum. Site new fills and backfllls should consist of good quality sandy granular D.G. import soils and mechanically compacted to a minimum of 95% compaction levels unless otherwise specified or directed in the field. Finish rough and final pad grade tests shall be required regardless of fill thickness. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 28 * Foundation trench and subgrade soil observation - After the foundation trench excavations and prior to the placement of steel reinforcing for proper moisture and specified compaction levels. * Geotechnical foundation/slab steel observation - After the steel placement is completed but before the scheduled concrete pour. Underground utility, plumbing and storm drain trench Observation - After the trench excavations but before placement of pipe bedding or installation of the underground facilities. Local and Cal-OSHA safety requirements for open excavations apply. Observations and testing of pipe bedding may also be required by the project geotechnical engineer. * Underground utility, plumbing and storm drain trench backfill observation - After the backfill placement is started above the pipe zone but before the vertical height of backfill exceeds 2 feet. Testing of the backfill within the pipe zone may also be required by the governing agencies. Pipe bedding and backfill materials shall conform to the governing agencies' requirements and project soils report if applicable. Trench back fills shall consist of good quality sandy granular D.G. import soils, mechanically compacted to a minimum of 95% compaction levels, unless otherwise specified. Plumbing trenches more than 12 inches deep maximum under the floor slabs should also be mechanically compacted and tested for a minimum of 95% compaction levels. Flooding or jetting techniques as a means of compaction method should not be allowed. * Improvement subgrade observation - Prior to the placement of concrete for proper moisture and specified compaction levels. B. Post-Tensioned Rigid Raft Foundation Slab As a minimum, the proposed residential dwelling may be supported on a shallow stiff rigid raft post-tensioned type foundations. Other foundation system alternatives, as presented in the referenced reports, still remain valid and are also available for considerations. The choice of appropriate option will depend on acceptable levels of future building and improvement performance, economic feasibility and ease of constructions. Geotechnical concept designs (not for construction) of the recommended rigid raft post- tensioned type foundations are depicted on the enclosed Typical Foundation Plan and Typical Interior Stiffenérs Detail, Figures 12 and 13 respectively. Added or modified recommendations may also be necessary and should be given at the time of foundation plan review phase and completion of the monitoring period, as specified herein. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 29 Actual rigid raft post-tensioned type foundation designs should be completed by the project structural engineer or design/build contractor. However, the following soil design parameters and minimum requirements are appropriate and should be considered in the final designs and implemented during the construction phase: * The rigid raft type foundation design should consider a post-tensioned slab with perimeter exterior beams and interior stiffeners (ribbed foundation), as conceptually shown on the enclosed Figures 12 and 13. * All designs shall conform to the latest addition of the California Building Code (CBC), specifications of the Post-Tensioning Institute (PTI), local standards, and the specifications given in this report. * Foundation bearing soils should be inspected and tested as necessary prior to trenching and actual construction by the project geotechnical engineer. The required foundation bearing soils in-place densities, and specified moisture contents should be confirmed prior to the foundation pour * A well-performing vapor barrier/moisture retardant (minimum 15-mil Stego) should be placed over the compacted subgrade and overlain by 4 inches of good quality well-graded clean sand. Alternatively, a 4-inch thick base of 1/2 inch clean aggregate and a vapor barrier (minimum 15-mil Stego) in direct contact with concrete, and a concrete mix design, which will address bleeding, shrinkage and curling (ACI 302.2R-06) may also be considered per California Green Building Standards Code (4.505.2). * At the completion of ground and subgrade preparation as specified, and approval of the project geotechnical engineer, the rigid raft post-tensioned type foundations should be constructed as detailed on the structural/construction drawings. * Based on our experience on similar projects, available laboratory testing and analysis of the test results, the following soil design parameters are appropriate: - Design predominant clay mineral type .....................Montmorillonite. - Design percent of clay in soil .....................................60 %. - Design effective plasticity index .....................................45. - Design depth to constant soil suction ...............................7 feet. - Design constant soil suction ......................................Pf 3.6. - Design velocity of moisture flow ..........................0.70 inch/month. - Thornwaite Moisture Index for edge lift ....................................0. - Thornwaite Moisture Index for center lift ... ...........................-20. - Design edge moisture variation distance for center lift (em) ...........8.0 feet. - Design edge moisture variation distance for edge lift (em) ............3.5 feet. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 30 - Design differential swell occurring at the perimeter of slab for center lift condition (Ym) ................................1.0 inch(es). - Design differential swell occurring at the perimeter of slab for edge lift condition (Ym) ..................................2.25 inches. - Design soilsubgrade modulus (k) ..................................100 pci. - Design net allowable bearing pressure for post-tensioned foundations ...................................1000 psf. Notes: * Internal net allowable foundation pressure within the perimeter of the post-tension slab should be considered 1000 psf for a minimum embedment depth of 12 inches, and may be increased 20% for each additional foot of embedment or a portion thereof to a maximum of 3000 psf. The net allowable foundation pressure provided herein applies to dead plus live loads and may be increased by one-third for wind and seismic loading. * Provide a minimum 18 inches wide by 24 inches deep exterior beams and interior longitudinal stiffeners reinforced with at least 245 continuous bars near the bottom and #3 ties at 18 inches on centers maximum (see Figures 12 and 13). Provide additional minimum 15 inches wide by 18 inches deep interior transverse stiffeners reinforced with at least 245 continuous bars near the bottom and #3 ties at 30 inches on center maximum. Stiffeners spacing shall not exceed 12 feet maximum center to center in bbth directions, as shown in the enclosed Typical Foundation Plan, Figure 12. Final design dimensions and spacing of interior stiffening beams should be furthered confirmed or revised as necessary based on the recorded settlement monitoring data at the completion of pad construction. Perimeter beams and interior stiffener embedment depths are measured from the lowest adjacent ground surface, not including the sand/gravel beneath the slabs. Exterior beams shall also enclose the entire building circumference. * The rigid raft post-tension type foundation slab shall not be less than 6 inches in thickness minimum. We recommend considering pre-tensioning in order to preclude early concrete shrinkage cracking. Also, see Site Corrosion Assessment section of this report for concrete type and strength. C. Soil Design Parameters Soil design parameters provided in the referenced reports are still valid and may be considered where appropriate and as applicable unless superceded below. Good quality sandy granular D.G. type import soils are also recommended herein placed within upper pad grades. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 31 The following soil design parameters are based upon on our past experience with similar projects in close vicinity of the study site, and available test results performed on representative samples of onsite and import earth materials: * Design soil unit weight = 124 pcf. * Design angle of internal friction of soil = 26 degrees. * Design active soil pressure for retaining structures = 40 pcf (EFP), level backfill, cantilever, unrestrained walls. * Design at-rest soil pressure for retaining structures 60 pcf (EFP), non-yielding, restrained walls. * Design soil passive resistance for retaining structures = 200 pcf (EFP), level ground surface on the toe side. * Design coefficient of friction for concrete on soil = 0.25. * Net allowable foundation pressure for 95% compacted fills = 2000 psf. * Allowable lateral bearing pressure (all structures except retaining walls) for on-site compacted fill = 100 psf/ft. Notes: * Use a minimum safety factor of 1.5 for wall over-turning and sliding stability. However, because large movements must take place before maximum passive resistance can be developed, a minimum safety factor of 2 may be considered for sliding stability particularly where sensitive structures and improvements are planned near or on top of retaining walls. * When combining passive pressure and frictional resistance, the passive component should be reduced by one-third. * The allowable foundation pressures provided herein apply to dead plus live loads and may be increased by one-third for wind and seismic loading. * The lateral bearing earth pressures may be increased by the amount of designated value for each additional foot of depth to a maximum 1500 pounds per square foot. D. Inter-Locking Payers Flexible interlocking concrete payers are proposed as shown on the enclosed Figure 1 and should be installed in accordance with the manufacturer's recommendations. Subgrade preparation and compaction procedures will remain the same as specified herein, unless otherwise approved. Also refer to Stormwater BMPs/Permeable Interlocking Concrete Payers (PICP) section of this report, and the attached Figure 8 for typical geotechnical design and construction recommendations. Some repairs and period maintenance of interlocking Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31) 4547 Cove Drive, Carlsbad, California Page 32 payers may be required depending on subgrade behavior, as wells as design and installation/construction procedures and should be anticipated. XII. GENERAL RECOMMENDATIONS The minimum foundation design and steel reinforcement provided herein are based on soil characteristics and are not intended to be in lieu of dimensions and reinforcement necessary for structural considerations. Adequate staking and grading control are critical factors in properly completing the recommended remedial and site grading operations. Grading control and staking should be provided by the project grading contractor or surveyor/civil engineer, and is beyond the geotechnical engineering services. Staking should apply the required setbacks shown on the approved plans and conform to setback requirements established by the governing agencies and applicable codes for off-site private and public properties and property lines, utility easements, right-of-ways, nearby structures and improvements, and graded embankments. Inadequate sOtaking and/or lack of grading control may result in illegal encroachments or unnecessary additional grading which will increase constiuction costs. Open or backfilled trenches parallel with a footing shall not be below a projected plane having a downward slope of 1-unit vertical to 2 units horizontal (50%) from a line 9 inches above the bottom edge of the footing, and not closer than 18 inches from the face of such footing. Where pipes cross under-footings, the footings shall be specially designed. Pipe sleeves shall be provided where pipes cross through footings or footing walls, and sleeve clearances shall provide for possible footing settlement, but not less than 1-inch all around the pipe. Expansive clayey soils should not be used for backfihling of any retaining structure. All retaining walls should be provided with a 1:1 wedge of granular, compacted backfill measured from the base of the wall footing to the finished surface and a well-constructed back drain system as shown on the enclosed Figure 14. Planting large trees behind site retaining walls should be avoided. All underground utility and plumbing trenches should be mechanically compacted to a minimum of 95% of the maximum dry density of the soil unless otherwise specified. Care should betaken not to crush the utilities or pipes during the compaction of the soil. Very low expansive, granularD.G. type import backfill soils should be used. Trench backfill materials and compaction beneath pavements within the public right-of-way, shall conform to the requirements of governing agencies. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 33 Onsite soils consist of expansive and moisture sensitive silty to clayey soils. These deposits can experience movements and undergo s volume changes upon wetting and drying. Maintaining a uniform as-graded soil moisture during the post construction periods is essential in the future performance and stability of site structures and improvements. Excessive irrigation resulting in wet soil conditions should be avoided. Surface water should not be allowed to infiltrate into the underlying bearing and subgrade soil. Site drainage over the finished pad surfaces should flow away from structures in a positive manner. Care should be taken during the construction, improvements, and fine grading phases not to disrupt the designed drainage patterns. Roof lines of the buildings should be provided with roof gutters. Roof water should be collected and directed away from the buildings and structures to a suitable location. Final plans should reflect preliminary recommendations given in this report. Final foundations and grading plans may also be reviewed by the project geotechnical consultant for conformance with the requirements of the geotechnical investigation report outlined herein. More specific recommendations may be necessary and should be given when final grading and architectural/structural drawings are available. All foundation trenches should be inspected to ensure adequate footing embedment and confirm competent bearing soils. Foundation and slab reinforcements should also be inspected and approved by the project geotechnical consultant. The amount of shrinkage and related cracks that occur in the concrete slab-on-grades, flatwork and driveways depend on many factors, the most important of which is the amount of water in the concrete mix. The purpose of the slab reinforcement is to keep normal concrete shrinkage cracks closed tightly. The amount of concrete shrinkage can be minimized by reducing the amount of water in the mix. To keep shrinkage to a minimum the following should be considered: * Use the stiffest mix that can be handled and consolidated satisfactorily. Use the largest maximum size of aggregate that is practical. For example, concrete made with %-inch maximum size aggregate usually require about 40-lbs. more (nearly 5-gal.) water per cubic yard than concrete with 1-inch aggregate. * Cure the concrete as long as practical. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 34 The amount of slab reinforcement provided for conventional slab-on-grade construction considers that good quality concrete materials, proportioning, craftsmanship, and control tests where appropriate and applicable are provided. 12. A preconstruction meeting between representatives of this office, the property owner or planner, city inspector as well as the grading contractor/builder is recommended in order to discuss grading and construction details associated with site development. XIII. GEOTECHNICAL ENGINEER OF RECORD (GER SMS Geotechnical Solutions, Inc. is the geotechnical engineer of record (GER) for providing a specific scope of work or professional service under a contractual agreement unless it is terminated or canceled by either the client or our firm. In the event a new geotechnical consultant or soils engineering firm is hired to provide added engineering services, professional consultations, engineering observations and compaction testing, SMS Geotechnical Solutions, Inc. will no longer be the geotechnical engineer of the record. Project transfer should be completed in accordance with the California Geotechnical Engineering Association (CGEA) Recommended Practice for Transfer of Jobs Between Consultants. The new geotechnical consultant or soils engineering firm should review all previous geotechnical documents, conduct an independent study, and provide appropriate confirmations, revisions or design modifications to his own satisfaction. The new geotechnical consultant or soils engineering firm should also notify in writing SMS Geotechnical Solutions, Inc. and submit proper notification to the City of Carlsbad for the assumption of responsibility in accordance with the applicable codes and standards (1997 UBC Section 3317.8). XIV.. LIMITATIONS The conclusions and recommendations provided herein have been based on available data obtained from the review of pertinent prior documents, reports and plans, available subsurface explorations and laboratory testing, as well as our experience with the soils and formational materials located in the general area. The materials encountered on the project site and utilized in our laboratory testing are believed representative of the total area; however, earth materials may vary in characteristics between excavations. Of necessity, we must assume a certain degree of continuity between exploratory excavations and/or natural exposures. It is necessary, therefore, that all observations, conclusions, and recommendations are verified during the grading operation. In the event discrepancies are noted, we should be contacted immediately so that an inspection can be made and additional recommendations issued if required. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 35 Several stabilization and project development options with their "pros" and "cons" of each option are presented herein. The final choice of an option will depend on site limitations, acceptable levels of risk and future building performance, economic feasibility and ease of construction. It is the responsibility of the property owner(s) to carefully evaluate the pros and cons and cost-benefit aspects of each alternative with a risk level acceptable to them for choosing a specific mitigation and development technique. The selection of a desired development alternative and mitigation procedure, considered with the risk level acceptable to current owners/developers should be passed onto the future homeowner(s). The recommendations made in this report are applicable to the site at the time this report was prepared. It is the responsibility of the owner/developer to ensure that these recommendations are carried out in the field. It is almost impossible to predict with certainty the future performance of a property. The future behavior of the site is also dependent on numerous unpredictable variables, such as earthquakes, rainfall, and on-site drainage patterns. The firm of SMS Geotechnical Solutions, Inc., shall not be held responsible for changes to the physical conditions of the property such as addition of fill soils or changing drainage patterns which occur without our inspection or control. This report should be considered valid for a period of one year and is subject to review by our firm fèllowing that time. If significant modifications are made to your tentative construction plan, especially with respect to finish pad elevations final layout, this report must be presented to us for review and possible revision. This report is issued with the understanding that the owner or his representative is responsible for ensuring that the information and recommendations are provided to the project architect/structural engineer so that they can be incorporated into the plans. Necessary steps shall be taken to ensure that the project general contractor and subcontractors carry out such recommendations during construction. The project geotechnical engineer should be provided the opportunity for a general review of the project final design plans and specifications in order to ensure that the recommendations provided in this report are properly interpreted and implemented. If the project geotechnical engineer is not provided the opportunity of making these reviews, he can assume no responsibility for misinterpretation of his recommendations. SMS Geotechnical Solutions, Inc., warrants that this report has been prepared within the limits prescribed by our client with the usual thoroughness and competence of the engineering profession. No other warranty or representation, either expressed or implied, is included or intended. Geotechnical Update Report, Proposed Residential Duplex Development July 25, 2016 Existing Pad (Lot 31), 4547 Cove Drive, Carlsbad, California Page 36 Once again, should any questions arise concerning this report, please do not hesitate to contact this office. Reference to our Project No GI-16-06-128 will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. SMS Geotechnical Solutions, Inc. di S. Shariat 2 )I4LJ (P No. 2362 Steven J. Meizer C" re- CE CEG #2362. ENGINEERING ' GEOLOGIST Distribution: Addressee (5, e-mail) 4 GEOTECHNICAL SOLUTIONS. INC. REFERENCES - Annual Book of ASTM Standards, Section 4 - Construction, Volume 04.08: Soil and Rock (I); D420 - D5876,2016. - Annual Book of ASTM Standards, Section 4 - Construction, Volume 04.09: Soil and Rock (II); D5877 - Latest, 2016. - Highway Design Manual, Caltrans. Fifth Edition. - Corrosion Guidelines, Caltrans, Version 1.0, September 2003. - California Building Code (CBC), California Code of Regulations Title 24, Part 2, Volumes I & 2, 2013, International Code Council. - "The Green Book" Standard Specifications For Public Works Construction, Public Works Standards, Inc., BNi Building News, 2015 Edition. - California Geological Survey, 2008 (Revised), Guidelines for Evaluating and Mitigating Seismic Hazards in California, Special Publication 11 7A, 108p. - California Department of Conservation, Division of Mines and Geology (California Geological Survey), 1986 (revised), Guidelines for Preparing Engineering Geology Reports: DMG Note 44. - California Department of Conservation, Division of Mines and Geology (California Geological Survey), 1986 (revised), Guidelines to Geologic and Seismic Reports: DMG Note 42. - EQFAULT, Ver. 3.00, 1997, Deterministic Estimation of Peak Acceleration from Digitized Faults, Computer Program, T. Blake Computer Services and Software. - EQSEARCH, Ver 3.00, 1997, Estimation of Peak Acceleration from California Earthquake Catalogs, Computer Program, T. Blake Computer Services and Software. - Tan S.S. and Kennedy, M.P., 1996, Geologic Maps of the Northwestern Part of San Diego County, California, Plate(s) 1 and 2, Open File-Report 96-02, California Division of Mines and Geology, .1:24,000. - "Proceeding of The NCEER Workshop on Evaluation of Liquefaction Resistance Soils," Edited by T. Leslie Youd and Izzat M. Idriss, Technical Report NCEER-97-0022, Dated December 31, 1997. - "Recommended Procedures For Implementation of DMG Special Publication 117 Guidelines For Analyzing and Mitigation Liquefaction in California," Southern California Earthquake Center; USC, March 1999. REFERENCES (continued) - "Soil Mechanics," Naval Facilities Engineering Command, DM 7.01. - "Foundations & Earth Structures," Naval Facilities Engineering Command, DM 7.02. - "Introduction to Geotechnical Engineering, Robert D. Holtz, William D. Kovacs. - "Introductory Soil Mechanics and Foundations: Geotechnical Engineering," George F. Sowers, Fourth Edition. - "Foundation Analysis and Design," Joseph E. Bowels. - Caterpillar Performance Handbook, Edition 29, 1998. - Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas, California Division of Mines and Geology, Geologic Data Map Series, No. 6. - Kennedy, M.P., 1977, Recency and Character of Faulting Along the Elsinore Fault Zone in Southern Riverside County, California, Special Report 131, California Division of Mines and Geology, Plate I (East/West), 12p. - Kennedy, M.P. and Peterson, G.L., 1975, Geology of the San Diego Metropolitan Area, California: California Division of Mines and Geology Bulletin 200, 56p. - Kennedy, M.P. and Tan, S.S., 1977, Geology of National City, Imperial Beach and Otay Mesa Quadrangles, Southern San Diego Metropolitan Area, California, Map Sheet 24, California Division of Mines and Geology, 1:24,000. - Kennedy, M.P., Tan, S.S., Chapman, R.H., and Chase, G.W., 1975, Character and Recency of Faulting, San Diego Metropolitan Areas, California: Special Report 123, 33p. - "An Engineering Manual For Slope Stability Studies," J.M. Duncan, A.L. Buchignani and Marius De Wet, Virginia Polytechnic Institute and State University, March 1987. - "Procedure To Evaluate Earthquake-Induced Settlements in Dry Sandy Soils," Daniel Pradel, ASCE Journal of Geotechnical & Geoenvironmental Engineering, Volume 124, #4, 1998. - "Minimum Design Loads For Buildings and Other Structures," ASCE 7-10, American Society of Civil Engineers (ASCE). - •41] Bf +10 RZtiw@ TIME :G(sjoT -10 -20 -30 7 PROPOSED BIORETENTION LIDJ +10 -10 -20 -30 'FORMATIONAL ROCK IIIIIfIIITIT T-1-40 -1----L-1-- LOGOONAL DEPOSIT EXISTING EXISTING BUILDIND BUILDIND PROPOSED BUILDING A A 9 +10 4 +10 FILL If1 cw TIME OF DRILLING (8/13/03) ° -10 - - --10 LAGOONAL DEPOSIT. -20- . - -20 GEOLOGIC CROSS-SECTIONS PROPOSED BUILDING SCALE: F' = 20' FAULT-EPICENTER MAP SAN DIEGO COUNTY REGION _% J/ .---------. I rfi I o 1 •\ON I' • / ' • • 76 0 --- __ £ r / F RIVER1DE • 1r.•: OwLO 4. S •'4J ' •-•--; Jf I ••- •& I .1 • \ \(..-A SITE \' rJ. ' I \ \. rt r•. rr I, I • ____ __4 W _ - : k\. • • • - ..; _--- •. - Indicated Earthquake Events Through A 200 Year Period EPICENTER MAP LEGEND - • -e:o- 1IJ- i- 1a2. I ,,,) •.. I F1-4 • • . : • 5 5 . . t1iIc',t. HV-IF -.Ij1IIq - iMifrf L~4t La_ WJJM3 Map is reproduced from California Division of Mines and Geology, "Epicenters of! and Areas Damaged by M > 5 California Earthquakes, 1800-1999". ~Fmung 8] TSUNAMI INUNDATION MAP Oceanside I San Luis Rey Quadrangles SITE Scale: 1:12,000 -''--- Tsunami Inundation Line Tsunami Inundation Area ( FOGURE '4 ) ONE X:, _ 'RANCFrOMHJAHIDAONTMAMD GRANT I& MAP SCALE 1" = 500' 0 250 500 750 1,000 ::i FEET PANEL 0764G ~> EA BLUFF Cl_ct SITE FIRM FLOOD INSURANCE RATE MAP SAN DIEGO COUNTY, CALIFORNIA AND INCORPORATED AREAS PANEL 764 OF 2375 (SEE MAP INDEX FOR FIRM PANEL LAYOUT) CONTAII4I cOMMUNir,, NUMSE RANEL SUFFIX At1 C1 FY OF an,,,c nc. c .olice Ic Uc.c TN Mp NIrn,b., *oc, bcI, .hocld be uc.d cA,c pcnp map ccl,,, It,. Co,rnrnmtty Ncc.t, .Icc,, Icc anculd t aM vn In,u,anc. appticaRcno or tic suL$,U MAP NUMBER 06073C0764G AG GA MAY 16, 2012 D;oNDA 'I MAP REVISED LiQ2iV It! ;JFederal Emergency Management Agency J 24 This ian official copy of portion of the above referenced flood map, It w2s extracted using F-MIT On-Line. This map does not reflect changes or amendmenis whinh may have been madc subsequent tu the date on the titic block, Fo. 11- 1.1~i pinduct IMY61'Imabon about National Fluud Insurance Program flood maps checkthe FEMA Flood Map Store 2tvAvwmscJema.9ov I oiii —II LEGEND SPECIAL FLOOD HAZARD AREAS SUBJECT TO INUNDATION BY THE - - 1% ANNUAL CHANCE FLOOD MAP SCALE 1" 500' The 1% annual chance flood (1007-year flood), also known as the base flood, is the flood that has a 0 250 500 750 1,000 1% chance of being equaled or exceeded In any given year. The Special Flood Hazard Area is the . .. 1 FEET area subject to flooding by the 1% annual chance flood. Areas of Special Flood Hazard include Zones A, AE, AH, AO, AR, A99, V1 and yE. The Base Flood Elevation Is the water-surface elevation of the 1% annual chance flood. ZONE A No Base Flood Elevations determined. PANEL 0764G ZONE AE Base Flood Elevations determined. IJ.j ZONEAH Flood depths of 1 to 3 feet (usually areas of ponding); Base Flood Elevations W,i . i FIRM determined. h. FLOOD INSURANCE RATE MAP ZONE AO Flood depths of 1 to 3 feet (usually sheet flow on sloping terrain); average depths (D) determined. For areas of alluvial fan flooding, velocities also determined. i;i o SAN DIEGO COUNTY, I CALIFORNIA ZONE AR Special Flood Hazard Area formerly protected from the 1% annual chance flood by a flood control system that was subsequently decertified. Zone AR indicates that •: :1 AND INCORPORATED AREAS the former flood control system is being restored to provide protection from the 1% annual chance or greater flood. PANEL 764 OF 2375 ZONE A99 Areas to be protected from 1% annual chance flood event by a Federal flood (SEE MAP INDEX FOR FIRM PANEL LAYOUT) protection system under construction; no Base Flood Elevations determined. CONTAINS: COMMUNITY NUMBER PANEL SUFFI C' ARI SUAn. CAW OF ZONE V Coastal flood zone with velocity hazard (wave action); no Base Flood Elevations ift .: rfiees 0164 C determined. ZONE VE Coastal flood zone with velocity hazard (wave action); Base Flood Elevations determined. FLOODWAY AREAS IN ZONE AE N1 The floodway is the channel of a stream plus any adjacent floodplain areas that must be kept free of 1: katice to User. The Mop Numb., 90w below .IowI1 be used encroachment so that the 1% annual chance flood can be carried without substantial increases in flood heights. :: oommurdly. I: MAP NUMBER 06073C0764G J OTHER FLOOD AREAS Ii MAP REVISED ZONE X Areas of 0.2% annual chance flood; areas of 1% annual chance flood with average MAY 16, 2012 depths of less than 1 foot or with drainage areas less than 1 square mile; and :1) areas protected by levees from 1% annual chance flood. '. Federal Emergency ManagementAgency - I I OTHER AREAS Ths Is an official copy of a portion of the above rcmnced flood map. It ZONE X Areas determined to be outside the 0.2% annual chance floodplain was extracted using F-MIT On-Line This map does not reflect changes [Program r amendments which may have been made subsequent to the date on the ZONE D Areas In which flood hazards are undetermined, but possible. Wa block. For the latest product InlbrmatIon about Natiønel Flood Insurance flood maps check the FEMA Flood Map Store at ww.msc.rsmagc [IQFt i.'1 - 18" HOPE STORM DRAIN RISER w/A TRIUM 120 MAX PONOED WATER DEPTH VARIES MULCH :6*. ::.:•: PIPE; HOPE OR PVC —" ....... GEOMEMBRANE THICKNESS AT LEAST JOMIL 3" MINIMUN (TYP) AGGREGATE BELOW UNDERORAIN TO AVOID CLOGGING U. Z_(MIN) , i '—HDPE OR PVC on 5 GR ,A * GEOMEMBRANE * THICKNESS AT LEAST 30MIL MIN DEEP TH1.5—" SOIL F1L TER MIX PERFORA TED PIPE SLOPED OUT A T 0.5% IN 3%" AGGREGA TE PIPE BASE GRA VEL BED. CONNECTED TO STORM DRAIN. Low Schematic And Conceptual Only No-Scale 2GE011cl1NJcAl. SOLUTIONS, INC O© TTFJ©I TOL J 5931 Sea Lion Place, Suite 109 Carlsbad, California 92010 ATE: [FIGURE NO: (760) 602-7815 Y srnsgeosoLinc(a)gmail.com (00_u '2.' JLY r NO. 8 ACGREGATES IN OPENINGS PERCURB MANUFACTURER SPECS r PERMEABLE PAVERS / (TRAFFIC RATED) ,,- 3-1/8" THICK CONCRETE PAVERS, TRAFFiC LOADING 6" CONCRETE EDGE RESTRAIN BEDDING COURSE (NO. 8 AGGREGATE Of? PER MANUFACTURER SPECS) "THICK OPEN GRADED BASE, WIN MIN. 5 PER HOUR /NF7L TRA liON RATE (No. 57 STONE - 3/4" MAX.) THICKNESS AT LEAST JOMIL '- OPEN GRADED \ BASE (NO. 57 \ STONE-3/4" MAX.) SOIL S(JBGRADE UPPER 12" AT 95% COMPAC71QN. (ASPI 07557) Schematic And Conceptual Only No-Scale 4" PERFORATED UNDERDRAIN SCH. 40 PVC. CONNECT TO PERFORA TED PIPES UNDER THE BIORETEN liON AREAS. GEOTECHNICAL SOLUTIONS, INC. 5931 Sea Lion Place, Suite 109 Carlsbad, California 92010 (760) 602-7815 smsgeosol.incgmjJ 0 TY10L PERMEABLE PAVER 11"L 1. - wurr- ECT NO: DATE: IFIGURE NO: JLLfl? ©uJ Ii NOTE: CONCEPTUAL& SCHEMATIC ONLY. SUBJECT TO FIELD MODIFICATIONS BY GEO. ENG. 11!)1}lEL NO-SCALE EXTG BLG NEW BLG. (WP) MIN. 6 THI<. POSTTENSiONED FNO. / 7/ MW. 18'W04D PERIM. G.B. ,/ MW. 18WX240 INTERIOR STIFFENING BEAMS W/2-#5 NEAR BOTT. MN. / ' / WI245 NEAR BOlT. MIN. @ 12 O.C. EACH WAY /7 (NP) - -- - - - / 3?) TEMP. CONST. SLOPE. INITIALLY AT 1:1 PL(?) BENCH INTO IT AT LIMITED SECTION DURING ROCK PLACEMENT& IMMIDIATELY BACKFiLL (ALSO SEE REPORT) \ \ SETTLEMENT PLATES (SEE REPORT) I MN%COMPDALL 12.flr1i L_1_E)CrGFND.(TYP) APPROX. WATER TABLE - -- 277:____. . \LOWER W BELOW BOTTOM OF EXCAV FILL AS NECESSARY APPROX. CONTACT SOFT LAGOON DEPOSITS TERRAGRID FiX 1200 OR GREATER (SEE REPORT) APPROX. 6 LAYER OF1-1/7T03/4 CRUSHED ROCKS / \if J I SHORINGIPILEOVP.) TRACKED-WALKED W/HEAW CONST. EQUP. (1VP) / MIRAFT 500X (OR GREATER) SEPARATION FABRIC I I ON TOP OF TRACKED-WALKED ROCK I SHORING/PILE (IYP.) PLACE & TRACK-WALK MINUS 12 ANGUALAR ROCKS TRACK-WALKED WIHEAVY CONST. EQUP. TO DISPLACE SOFT PUMPING SOIL AND INTERCLOCKED TO ESTABLISH PRIM NON-YIELDING BOTTOM. ADD ROCKS AS NECESSARY AND CONT. TRACK-WALKING TO ACHIEVE NON-YIELDING CONDI11OS, AS APPROVED IN THE FIELD (ALSO SEE REPORT) W-SHAPE MP) CONC. PILE (TYP) -- --:j) MIN. 3-SACK CONC. SLURRY (NP) F LAGGING (NP) 8 C.C. MAX. EXCAV. GACKCUT PL?) MIN. 3-SACK CONC. SLURRY (NP) OC.C.MAX. L 1 J 2 MIN. TYPICAL GROUND STABILIZATION, N-S DIRECTION TOP OF SLOPE 15 MI ------ NEW BLDG. (1vP N. 12MAX. 12'MAX. 12MAX. 12' MAX. 12MAX. INTERIOR STIFFENING BEAMS SETTLEMENT PLATES cr?P) -\ PERIMETER $.B.(IYP) / PERIMETER G.E. (lYP) EXISTING RIP-RAP SLOPE rmT*if J 2 çUTILITY TRENCH (TYP) %COMPD FILL (TYP) 12MIN SEA I.EVEL(TYP) i ABLE LOWER WATER BELOW BOTTOM OF EXCAV., AS NECESSARY ______ ALL 1 ,.\.. ....._.7- ....... _______ _?-APPROX. CONTACT -V __VVV SOFT LAGOON DEPOSITS MINUS 12 ANGULAR ROCKS TERRAGRIO RX-1200 OR GREATER \ 1-1/2 TO 3/4• CRUSHED ROCKS MIRAFI 5OX OR GREATER (TYP) NOTE: CONCEPT1JAL& SCHEMA11N ONLY. SUBJCETTO FIELD MODIFICATION BY GEO, ERG, NO-SCALE. SEE TYPICAL GROUND STABILIZATION, N-S DIRECTION PLATE FOR DETAIL SPEC TYPICAL GROUND STABILIZATION, E-W DIRECTION SETTLEMENT PLATE SCHEMATIC NO SCALE H 2' 0 0--3/4I Drilled Holes (Typ) 2' 0 —Centered 2" Welded Cross-Bar or Nut f - - /8" Steel Plate j=. 0- i PLAN VIEW NOTE: Elevation to be Taken at Top of Uppermost Union f- Nail 2" Pipe Union or Slip Coupling Fill W/3—Sack Slurry 2" by 2,/2,,' Iron Pipe - (Thread at Both Ends if Pipe Union is Used) Spot Weld Three Places (Typ) - - 2" Pipe Union or Slip Joint '- Weld (Typ) NOTE: Total (New) Length of Base, Pipe & Union Three Places (Typ) (-P) to be Provided at Time of Installation of ld Each Extension a~4 Welded Cross-Bar or Nut 90 _A' Elil 111= 111= IllE PIlE \IIIE Steel Plate #4 Steel Reinforcement Bar 2' Length -111= 111= lIE CROSS-SECTION PROFILE SMS Geotechnical Solutions, Inc. ¶..45 t'4 caldjolF7l PTi1a 7doity stab / -j L4 .-. - cv —_3 T,d • EXTERIOR BE,4ts4 I' J - L p— (S-P-);I fbr2.e \ 2-5T twL (Yc( 16"?. c. m 0Th'PICAL FXTEREO DPEEJ FOOTING V (97- CONCEPTUAL ONLY NO-SCALE 222Z2 Iv,,', JwiE &?'. TYPICAL FOUNDATION PLAN, -4Ll .Difff Rigid Raft Post-Tensioned Slab T -- Fo(BURIE 12 Slab T n&fl (ij?) , i -r s i b (-ryP) / 5 6 r1T. (!.Y) )wL <- 4 /Ôt1OC. FX" 7' -r4 -+ E / 1 Pio-Ic, L_1 INTERIOR LoN1TuD1rL t4-S' 311FNES T 'tV) ,prs16 retkns can 15 Th 3 7T I Zop;onI7 Z E 7 C'd J,,,l J -, C3d- 2#5T- Oir. INTERIOR r N5v.1SE ( - W) $TtFF&NFPS TYPICAL INTERIOR STIFFENER DETAIL CONCEPTUAL ONLY NO-SCALE Fo(oung i's rl ATTACHMENT I Job #03-348-P February 27, 2008 Mr. Jerzy Lewak c/o Zijlstra Architecture 731 South Highway 101 Suite I L Solana Beach, California 92075 DRILLED CAISSON FOUNDATIONS, PROPOSED LBC CONDOMINIUM PROJECT, 4547 COVE DRIVE, CARLRAD, CALIFORNIA We now understand that the project condominium constructions will be supported on grade beams and drilled cast in-place (ClP) caissons with structural floors. Based on the project revised foundation plan and details prepared by Zijlstra Architecture (dated February 21, 2008) the building will be supported on 2 feet-10 inches diameter drilled caissons which will be extended 55 feet below the bottom of interconnecting grade beams (approximately 571/2 feet below existing grades). Lower floors will be designed 6% inches thick reinforced structural slabs spanning over the grade beams. Based on our review of project pertinent soil reports and drawings made available to us, the new revised caisson foundation system represents a feasible design from a geotechnical engineering point of view and maybe considered for structural support. The following comments, however, are appropriate and should be considered in the bfinal designs and implemented during the construction phase wherever appropriate and applicable: All conclusions and recommendations presented in the previous reports issued for this project remain valid except where specifically superseded or amended herein. Significant remedial grading works will not be required in the case of extended caisson foundations and structural floors. However, the upper soil remain loose susceptible to collapse and settlement which may impact site improvements and underground utilities. Remedial grading of these deposits consisting of removal and recompaction to a minimum of 3 feet or 12 inches below the deepest utility, whichever is more, will be necessary. Alternatively, flexible pipe joints and interlocking payers which can tolerate some movements should be considered. The caissons foundations should penetrate the upper loose fills and lagoon deposits and adequately embedded in to the underlying competent bedrock. Detail design and construction plans for the proposed caissons/piers, and associated grade beam foundations should be completed by the project architect/structural engineer. The following soil parameters are appropriate based on our previous site study and experience with similar earth deposits and should be used in the design, where applicable: * Estimated depths to competent sedimentary bedrock ............ * Estimated depths to groundwater ............................. * Minimum caisson embedment depth into competent bedrock * Minimum caisson diameter ....................... * Passive resistance (portion embedded into the firm bedrock only) * Net allowable caisson tip capacity in compression (with negative skin friction considerations) .............. * Depth to point of fixity below contact with the competent bedrock * Co-efficient of friction (portion embedded into the firm bedrock only) Notes: 50 feet. 5-7 feet. 7 feet 2/2 feet 450 pcf 12 ton(s) 1-foot 0.40 * The passive resistance provided for the competent bedrock can be increased by the amount of the designated value for each additional foot of depth to a maximum of 4500 psf. * Corrosion mitigation methods should be implemented as appropriate. Portland cement Type V (minimum f'c = 4500 psi, maximum water cement ratio = 0.45) as approved and determined appropriate by the project structural engineer should be used for concrete caissons, grade beams and structural floors. Caisson drilling will encounter loose alluvial soils and groundwater subject to caving and instability. Steel casing will be required to stabilize caisson shafts and should be anticipated. Drill fluid may be considered to stabilize lower shaft excavations with steel casing installed in upper portions near the surface. Large amounts of saturated and corrosive soils will be generated from the caisson shaft drilling. Proper construction sequencing and staging areas should be considered with generated spoil soils exported from the site as appropriate. Heavy dewatering will be necessary for removing groundwater intrusions into the drilled shafts using proper pumps and methods. Quality and quantity of discharge flow as well as discharge locations should be evaluated, identified and approved by respective agencies as required. Appropriate permits and compliance to the requirements of the governing agencies should also be obtained for proper dewatering discharge into public or natural facility. Standing water shall not be allowed at the bottom of caisson shaft during the steel cage placement and concrete pour. All shafts should be thoroughly cleaned to the satisfaction of the project geotechnical consultant. Free-fall of concrete in the drill shafts shall not be allowed. Concrete can be placed only upon approval of the geotechnical consultant using the "trimmie" techniques. All drilled shafts shall be plumb. Drill shafts which are more than 1% of their height maximum out-of-plumb shall be rejected and re-drilled. II. Actual depths to competent bedrock will likely vary at the site and should be determined by geotechnical inspections and physical measurements at the time. of caisson shaft inspections. 12. All caisson shafts should be inspected and approved by the project geotechnical consultant prior to the placement of steel cage and pouring the concrete. Special inspections will also be required for the still placement and concrete pour. The project contractor may prepare and submit to the architect/owner a detail work plan prior to the initiation of actual works. A table listing all construction works requiring special inspections may also be included in the project plans.' Engineering construction inspections and test results should be presented in written field and final reports. All design recommendations should be further field verified, confirmed, or revised if necessary. If you have any questions or need clarification, please do not hesitate to contact the undersigned. Reference to our Job #03-348-P will help to expedite our respOnse to your inquiries. We appreciate this opportunity to be of service to you. VINJE& MIDDLETON ENGINEERING, INC. S. Mehdi S. Shariat RCE #46174 Distribution: Addressee (2, fax) SPECIfICATIONS FOR CALTRANS CLASS 2 PERMEABLE MATERIAL (68-1.025) U.S. STANDARD SIEVE SIZE % PASSING 1" 100 3/4 90-100 3/8 40-100 No. 4 25-40 No. 8 18-33 No. 30 5-15 No. 50 0-7 No. 200 0-3 SAND EQUIVALENT> 75 FILTER MATERIAL, 3/40. CRUSHED ROCKS (WRAPPED IN FILTER FABRIC— OR CALTRANS CLASS 2 PERMEABLE MATERIALS (SEE SPECIFICATIONS) WATERPROOFING (1W) FINISH GRADE 6" MN. J 1-kil I NOSCALE] GROUND SURFACE 90% COMPACTED FILL APPROVED FILTER FABRIC (MIRAFI 12" MIN. 140N) 12' OVERLAP, TYP. ______ . u-i 1"MIN. LU 4' PVC PERFORATED PIPE MIN. (SCH 40 OR SDR35) MIN. 1/2% FALL TO APPROVED OUTLET (SEE REPORT) RETAINING WALL 2% MN CONCRETE-LINED DRAINAGE DITCH - - NATURAL OR GRADED SLOPE TEMPORARY RETAINING WALL 12" 1 CUT SLOP:: (TYP) PROPERLY . ./ COMPACTED (MIN. 90%) BACKFILLED GROUND ROCKS (WRAPPED IN FILTER FABRIC OR CALTRANS CLASS 2 PERMEABLE ____________• WATERPROOFING tth IPROPOSED IC7I) ILI - _•1i 1ff iii ISO- NXIMMININ e ' a irui Ipm lljii BENCH AND TIGHTLY KEY INTO TEMPORARY BACKCUT AS BACKFILLING PROGRESSES APPROVED FILTER FABRIC (MIRAFI 140N) 12" OVERLAPS 1W. I NOSCALEJ 4" PVC PERFORATED PIPE MIN. (SCH 40 OR SDR35) MN, 1/2% FALL TO APPROVED OUTLET (SEE REPORT) CONSTRUCTION SPECIFICATIONS: - Provide granular, non-expansive backfill soil in 1:1 gradient wedge behind wall, compact backfill to minimum 90% of laboratory standard. Backdrain should consist of 4" diameter PVC pipe (Schedule 40 or equivalent) with perforations down. Drain to suitable at minimum j %. Provide 3/4" - 1 f" crushed rocks filter materials wrapped in fabric (Mirafi 140N or equivalent). Delete filter fabric wrap if Caltrans Class 2 permeable material is used. Compact Class 2 permeable material to minimum 90% of laboratory standard. Seal back of wolf with approved waterproofing in accordance with architect's specifications. Provide posWve drainage to disallow poriding of water above wall. Drainage to flow away from wall at minimum 2%. Provide concrete-lined drainage ditch for slope toe retaining walls. Use 11 cubic feet per foot with granular backfill soil and 4 cubic foot per foot if expansive backfill is used. SMS GFOTFCKNCAL SOLUTIONS, INC. 1645 S. RANCHO SANTA FE ROAD, SUITE 20 SAN MARCOS, CA 9207 PHONE: 760-761-0799 EMAIL: TYPICAL RETAINING WALL LACK DAENAG PROJECT NO: FIGURE NO: ATTACHMENT II VINTE & MIDDLETON ENGINEERING, INC. Job #03-348-P September 25, 2006 Zijistra Architecture Attention: Mr. Sjirk Zijistra 731 South Highway 101 Suite I L Solana Beach, California 92075 2450 Vineyard Avenue Escondido, California 92029-1229 Phone (760) 743-1214 Fax (760) 739-0343 ENGINE- N, UPDATE, GEOTECHNICAL REPORT AND REMEDIAL GRADING GROUND STABILIZATION RECOMMENDATIONS, LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD, CALIFORNIA I. INTRODUCTION The project site was the subject of a previous geotechnical study performed by this office entitled "Preliminary Geotechnical investigation, Lot 31, Tract 5162, Cove Drive, Carlsbad, California," Job #03-3487P, dated March 3, 2004. Subsequent reports and letters consisted of "Addendum Geotechnical Report, Lot 31, Tract 5162, Cove Drive, Carlsbad, California," dated November 19, 2003, and "Foundation Plan Review, Proposed Three- Story Twin Homes, Lot 31, Tract 5162, Cove Drive, California," dated July 14, 2006. The referenced reports and letters are enclosed with this report as Appendices A through C, respectively. Based on our previous study, liquefaction of the underlying loose and saturated fills and Iagoonal deposits is the most significant geotechnical concern at the site. Consequently, driven pile and grade beam foundation supports were initially recommended and considered. We now understand that remedial grading and ground stabilization earthworks mitigation techniques as generally presented in the referenced Addendum Geotechnical Report (Appendix B), is being reconsidered. The purpose of this work was to review, the referenced reports and provide detailed recommendations that are consistent with remedial grading ground stabilization earthworks mitigation techniques. All conclusions and recommendations provided in the referenced reports and subsequent transmittals (Appendices A through C) remain valid and should be considered in final designs and implemented during the construction phase except where specifically superseded or amended below: Mr. Sjirk Zijlstra September 25, 2006 Page 2 II. REMEDIAL GRADING AND GROUND STABJUZATION Planned construction areas are underlain by loose to soft and saturated fills and alluvial soils which can undergo settlements and experience liquefaction and soil softening in their present conditions. Special ground stabilization and remedial grading techniques will be required in order to construct safe and stable building and pad surfaces as specified below. All grading and earthworks should be completed in accordance with Appendix Chapter 33 of the California Building Code, City of Carlsbad Grading Ordinances, the Standard Specifications for Public Works Construction, and the requirements of the following sections: Clearing and Grubbing: Remove trees, trash, debris, surface vegetation and other unsuitable/deleterious materials from all areas of planned new structures and improvements plus 5 feet minimum outside the perimeter where possible, and as directed in the field. Any construction debris generated from the demolition of existing site structures and improvements should also be properly removed and disposed of from the site. Vegetation, construction debris, grasses, lawns, trees, roots, stumps and other deleterious or unsuitable materials should be thoroughly removed and cleared from the construction site to the satisfaction of the project geotechnical consultant. All existing abandoned underground tanks, structures, pipes and irrigation lines should be properly removed from the construction areas. Existing underground utilities/plumbing in the construction areas should be pot-holed, identified and marked prior to the actual work. Abandoned pipes and irrigation lines should be properly capped and sealed-off to prevent any future water infiltrations into the foundation bearing and subgrade soils. Voids created by the removals of the abandoned underground utilities, pipes and structures should be properly backfilled with compacted fills in accordance with the requirements of this report. The prepared ground should be inspected and approved by the project geotechnical engineer or his designated representative. Dewatering: Groundwater was encountered at the project site at the depth of approximately 5 to 7 feet below the existing ground surfaces. Dewatering efforts should be anticipated to complete remedial grading and earthwork operations at the site depending on the actual watertable conditions at the time of grading. In the event of rise in watertable conditions due to seasonal and tidal conditions, some pre-dewatering may also be considered appropriate for this project. Any dewatenng technique suitable to the field conditions which can effectively remove the intruding water and allow soil removals and fill placement is considered acceptable provided it is approved by the project engineer. Dewatering should continue until completion of remedial grading operations and should be VINJE & MIDDLETON ENGINEERING INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 7434214 Mr. Sjirk Zijlstra September 25, 2006 Page 3 discontinued only upon approval of the project geotechnical engineer. Groundwater should be lowered a minimum of 2 feet below the specified bottom of over-excavation, toe of temporary slope or trench excavations unless otherwise directed in the field. Dewatering should not be allowed to adversely impact the nearby structures and improvements. The project contractor may wish to install instrumentations on sensitive nearby structures and improvements to monitor possible settlements and potential impacts of dewatering so necessary field adjustments can be made. Completing grading during dry seasons of the year and low tidal conditions, should be considered to minimize difficulties associated with dewatering operations. 3. Setbacks, Shoring and Temporary Construction Slopes: Excavations and removals adjacent to the existing structures and improvements should be done under inspection of the project geotechnical engineer. Undermining existing improvements and structures by the removal operations shall not be allowed. Top of temporary construction slopes should be adequately set back from the existing structures and improvements as directed in the field. Construction slopes required during trenching and removal operations should not exceed 1:1 gradients maximum with the watertable lowered a minimum 2 feet below the bottom of excavation. The remaining wedge of soil should then be benched out and new backfill tightly keyed-in as the fill placement progresses. Vertical trenches greater than 3 feet high maximum require continuous shoring. Temporary shoring excavation support should also be anticipated as it is required in the field by the project geotechnical consultant, or where adjacent and nearby structures and improvements prohibits laid back construction slopes. Any shoring system which can effectively allow for construction and provide safe and stable site conditions may be considered. Shoring should be provided as detailed on the approved Shoring Plans prepared by the project design/build contractor, based on the soils parameters provided herein. All temporary construction slopes require continuous geotechnical inspections during the remedial grading operations. Additional recommendations including revised slope gradients, set backs and the need for temporary shoring support should be given at that time as necessary. The project contractor shall also obtain appropriate permits, as needed, and conform to the Cal-OSHA and local governing agencies' requirements for trenching/open excavations and safety of the workmen during construction. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 1 Phone (760) 743-1214 Mr. Sjirk Zijlstra September 25, 2006 Page 4 4. Removals and Over-excavations: The building envelope plus a minimum of 5 feet where possible, and as directed in the field, should be over-excavated to a minimum depth of 5 feet below the existing ground levels and recompacted. Based on our subsurface exploratory excavations, the groundwater levels at the project areas are approximately 5 to 7 feet below the existing ground surfaces at the time of our field investigation and removal depths, may predominantly be near or above the indicated watertable levels. Building envelope includes all exterior pad footings, pop-outs, canopy supports, etc. Due to very loose to soft soils conditions in the project areas, appropriate construction equipment (such as an excavator) should be considered for soil removals. In the paving and improvement areas plus 3 feet outside the perimeter, removal depths should extend a minimum of 3 feet below the existing grades or 1-foot below the deepest utility, whichever is more, and recompacted. Deeper removals may be necessary based on the actual field exposures and should be anticipated; Actual depths should be established by the project geotechnical engineer at the time of remedial grading operations. The exposed bottom of over-excavation should be additionally prepared as directed in the field. All grounds steeper than 5:1 receiving fillslbackfills should be properly benched and keyed as directed in the field. 5. Stabilization Rock Blanket: The soft bottom of over-excavations in the building envelope plus a minimum of 5 feet, should be stabilized by placing minus 12-inch combined gradation rocks and tracking/consolidating with heavy construction equipments. Rock placement should continue until full rock interlocking conditions and non-yielding bottom of over-excavation is achieved as approved in the field by the project geotechnical engineer. Based on our experience with similar projects, rocks are typically pushed with heavy equipments approxfmately 2-3 feet into the soft soils before suitable bottom conditions are achieved. However, only actual site conditions will determine the quantity of rocks required to achieve non-yielding conditions. As a minimum and if groundwater conditions are favorable at the time of grading, dewatering sump pump(s) should be installed at low point(s) in the excavation as necessary, and become operational at the time of initial rock placement and remain in operations until completion of the bottom stabilization works is completed as direàted in the field by the project geotechnical consultant. In the case of a rise in groundwater due to tidal and seasonal conditions, more ambitious dewatenng methods will be necessary as specified. VNJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 Mr. SjirkZijlstra September 25, 2006 Page 5 Minus 11/2 inch rocks (combined gradation ranging from 1% inches to 1A-inch is also acceptable) should then be placed and tracked-in with heavy construction equipments over the minus 12-inch rocks to a minimum thickness of 6 inches unless otherwise directed in the field. A layer of Mirafi 500X soil separation fabric should then be laid over the approved bottom and covered with initial fill lifts of better qualiti on-site or sandy import soils which are properly moisture conditioned, carefully placed in thin (8 inches) horizontal layers, and compacted as directed in the field. In the paving and improvement areas, stabilization rock blanket is not required and earth reinforcement geogrid should be considered to create stable bottom of over- excavations suitable to receiving new fills and backfills. 6. Earth Reinforcement, Shrinkage, Fill Materials and Compaction: Upon approval of the project geotechnical engineer, a layer of Tensar Geognd BX-1 200 (or greater from the same series) should be neatly placed within the compacted fills approximately 2 feet above the Mirafi 500X soil separation fabric (at least 3 feet below the top of pad or 6 inches below the invert of utility lines, whichever is more). Subsequent fill lifts should then be carefully placed over the Geogrid and compacted until final grade elevations are achieved. Considerations should also be given to raise the building pad above the existing ground levels, as required, to accommodate the specified ground stabilization and bearing soils construction. All site fills and backfills should be adequately processed, thoroughly mixed, moisture conditioned to slightly above (2%) optimum moisture levels as directed in the field, placed in thin (8 inches maximum) uniform horizontal lifts and mechanically compacted to a minimum 95% of the corresponding laboratory maximum dry density, per ASTM, 0-1557, unless otherwise specified. On-site soils will shrink approximately 15% to 25% on volume basis when compacted to minimum 95% levels. Additional import soils, if required to complete remedial grading and achieve final design grades, should be good quality, non- corrosive, very low expansive granular sandy (SM/SW) deposits (100% passing %- inch sieve, more than 50% passing #4 sieve and less than 20% passing #200 sieve with expansion index less than 21), tested and approved by the project soils engineer prior to delivery to the site. Unexpected conditions may result in revised stabilization procedures including added rocks, fabrics and geogrid as established in the field. Field conditions will control actual stabilization procedures. VINIE & MIDDLETON ENGINEERING, INC. • 2450 Auto Park Way Escondido, California 92029-1229 • Phone (760) 743-1214 Mr. Sjirk Zijistra September 25, 2006 Page 6 7. Geotechnical Instrumentations and Monitoring: Geotechnical instrumentation devices consisting of two settlement plates and two settlement monuments should be installed at the project building site. The settlement plates should be placed at the bottom of the over-excavations to monitor settlement of the surcharged alluvium. The settlement monuments should be installed near the rough finish pad grades to monitor the post grading characteristics of the compacted fill mass. Geotechnical instrumentation sites should be installed at selected locations, not to interfere with the grading and post grading construction phases. Monitoring should be performed by means of field surveying shots periodically taken at each settlement plate installation site as the backfill placement progresses approximately once every 2 days. At the completion of remedial grading, monitoring should continue for both settlement plates and settlement monument sites on a bi-weekly and monthly basis as directed, until construction is completed. Surveying shots should be reduced (plotted versus time in days) by the project soils engineer, to establish settlement patterns and soil compression characteristics with respect to surcharge loading, dewatenng, compaction and earthworks activities, and self weight. Actual locations and construction details for the proposed settlement plates and settlement monuments should be given by the project geotechnical engineer at the time of initial field inspections prior to actual backfill and fill placement operations. Foundation trenching can only begin after completion (less than 0.01-foot or 0.12 inches between at least three consecutive readings per, monitoring schedule) of primary soil compression and the approval by the project geotechnical consultant. Foundation and slab recommendations provided in the following sections should also be confirmed and/or revised based upon the settlement monitoring data compiled at the completion of remedial grading operations. 8. Drainage and Erosion Control: A critical element to the continued stability of the graded building pads is adequate surface drainage and storm water control. This can most effectively be achieved by installation of appropriate drainage control systems per the project drainage improvement plans. Building pad surface run-off should be collected in approved drainage facilities and directed to selected locations in a controlled manner. Area drains should be installed. Surface and flood waters should not be allowed to impact site fills, structures and improvements, or penetrate into the underlying bearing soils. Storm water and surface run-off shall be diverted from entering the site. Temporary erosion control facilities and silt fences should be installed during the construction phase periods and until landscaping is fully established as indicated and specifiedon the approved project grading/erosion plans, VINJE & MIDDLTON ENGINEERING, INC. 2450 Vineyard Avenue Escondido, California 92029-I229 Phone (760) 743-1214 Mr. Sjirk Zijlstra September 25, 2006 Page 7 9. Engineering Inspections: All grading and earthwork operations including removals, suitability of earth deposits used as compacted fill and compaction procedures, should be continuously inspected and tested by the project geotechnical consultant and presented in the final as-graded compaction report. The nature of finished subgrade soils should also be confirmed in the final compaction report at the completion of grading. Geotechnical engineering inspections shall include, but not limited to the following: * Bottom of over-excavation inspection - After the bottom of over-excavation is exposed and prepared to receive stabilization rock blanket or geogrid, but before stabilization rock blanket or geogrid is installed. Excavation inspection - After the excavation is started, but before the vertical depth of excavation is more than 3 feet. This includes all temporary excavations, backcuts and underground trenching. Safety requirements enforced by the governing agencies for open excavations apply. * Fill/backfill inspection - After the fill/backfill placement is started, but before the vertical height of fill/backfill exceeds 2 feet. Special inspection of the initial fill lift and placement of geogrid earth reinforcement will also be necessary. Final rough and finish pad grade tests shall be required regardless of fill/backfill thickness. * Foundation trench inspection - After foundation trench excavations, but before steel placement. * Foundation bearing/slab subgrade soils inspection - Prior to the placement of concrete for proper moisture and specified compaction levels. * Foundation/slab steel inspection - After steel placement is completed, but before the scheduled concrete pour. * Subdrain/stabilization rock. blanket inspection - During the actual placement, all material shall conform to the project material specifications and approved by the project soils engineer. * Underground utility/plumbing trench inspection,- After the trench excavations, but before installation of the underground facilities. Safety requirements enforced by governing agencies for open excavations apply. Inspection of the pipe bedding may also be required by the project soils engineer. VrNJE & MIDDLETON ENGINEERING INC. • 2450 Vineyard Avenue ' Escondido, California 92029-I229 Phone (760) 743-1214 Mr. Sjirk Zijistra September 25, 2006 Page 8 * Underground utility/plumbing trench backfill inspection - After the backfill placement is started above the pipe zone, but before the vertical height of backfill exceeds 2 feet. Testing of the backfill within the pipe zone may also be required by the governing agencies. Pipe bedding and backfill materials shall conform to the requirements of governing agencies and project soils report if applicable. All trench backfills shall be mechanically compacted to a minimum 95% compaction levels per ASTM 0-1557, unless otherwise specified. Plumbing trenches over 12 inches deep maximum under the interior floor slabs should also be mechanically compacted and tested for a minimum 95% compaction levels. Flooding or jetting techniques as a means of compaction method shall not be allowed. * Improvements, subgrade inspections - Prior to the placement of concrete or asphalt for proper moisture and specified compaction levels. lii. MAT I GRADE BEAM FOUNDATIONS Concrete slab-on-ground mat foundations with interior and perimeter grade beams may be considered for building support. Actual mat foundation designs should be provided by the project structural engineer based on design loading conditions and following soil design parameters: As a minimum, concrete stab-on-ground mat foundations should be a minimum of 10 inches thick reinforced with minimum #4 bars at 16 inches on centers maximum each way, top and bottom. Interior and perimeter grade beams should be a minimum 18 inches wide and 24 inches deep reinforced with at least 245 bars top and bottom and #3 ties at 24 in on centers maximum. All depths are measured from the lowest adjacent ground level not including the sand/gravel layer under the mat. Exterior grade beams should enclose the entire building perimeter. Foundation mats should be underlain by 4 inches of clean sand (SE 30 or greater) which is provided with a well performing moisture barrier/vapor retardant (minimum 15-mil plastic) placed mid-height in the sand. In the case of good quality sandy subgrade import soils, as approved by the project geotechnical engineer, the moisture barrier/vapor retardant may be laid directly over the slab subgrade and covered with a minimum 2 inches of clean sand (SE 30 or greater). * Foundation bearing soils should be inspected and tested as required, to confirm specified conditions prior to poring the concrete. VINJE & MXDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 7434214 Mr. Sjirk Zijlstra September 25, 2006 Page 9 IV. EXTERIOR CONCRETE SLABS I FLATWORKS * All exterior slabs (walkways, patios) should be a minimum 4 inches in thickness, reinforced with #3 bars at 16 inches on centers in both directions placed mid-height in slab. Subgrade soils should be compacted to a minimum 95% compaction levels as specified. Provide "tool joint" or "softcut" contraction/control joints spaced 10 feet on center (not to exceed 10 feet maximum) each way. Tool or cut as soon as the slab will support weight and can be operated without disturbing the final finish which is normally within 2 hours after final finish at each control joint location or 150 psi to 800 psi. Tool or softcuts should be a minimum of 1-inch but should not exceed 1Y4- inches deep maximum. In case of softcut joints, anti-ravel skid plates should be used and replaced with each blade to avoid spalling and raveling. Avoid wheeled equipments across cuts for at least 24 hours. * All exterior slab designs should be confirmed in the final as-graded compaction report. Subgrade soils should be tested for proper moisture and specified compaction levels and approved by the project geotechnical consultant prior to the placement of concrete. V. SOILS PARAMETERS AND LATERAL EARTH PRESSURES The following soil design parameters are based on tested representative. samples of on-site earth deposits. All parameters should be re-evaluated when the characteristics of the final as-graded soils have been specifically determined: * Design wet density of on-site soil = 130 pcf. * Design angle of internal friction of on-site soil = 31 degrees. * Design active on-site soil pressure for retaining structures = 42 pcf (EFP), level backfill, cantilever, unrestrained walls. * Design at-rest on-site soil pressure for retaining structures = 63 pcf (EFP), non- yielding, restrained walls. * Design passive on-site soil resistance for retaining structures = 406 pcf (EFP), level surface at the toe. * Design co-efficient of friction for concrete on on-site soils = 0.38. * Design net allowable foundation pressure for 95% compacted fills = 2000 psf. * Allowable lateral bearing pressure (all structures except retaining walls) for on-site compacted fill = 200 psflft. * A soils module of subgrade reaction of 200 pci may be considered. VrNJE & MIDDLETON ENGINEERING, INC. 2450 ,Vineyard Avenue Escondido, California 920294229 0 Phone (760) 743-1214 Mr. Sjirk Zijistra September 25, 2006 Page 10 Notes: * Use a minimum safety factor of 1.5 for wall over-turning and sliding stability. However, because large movements must take place before maximum passive resistance can be developed, a safety factor of 2 may be considered for sliding stability where sensitive structures and improvements are planned near or on top of retaining walls. * When combining passive pressure and frictional resistance the passive component should be reduced by one-third. * The allowable foundation pressures provided herein also applies to dead plus live loads and may be increased by one-third for wind and seismic loading. * The allowable lateral bearing earth pressures may be increased by the amount of the designated value for each additional foot of depth to a maximum of 1500 pounds per square foot. * Use minimum 4500 psi concrete for mat foundation design (also see corrosion mitigation recommendations in enclosed References). Vi. ASPHALT AND PCC PAVEMENT DESIGN 1. Asphalt paving: Specific asphalt pavement designs can best be provided at the completion of rough grading based onR-value tests of the actual finish subgrade soils. However, a minimum section of 3 inches asphalt on 8 inches Class 2 aggregate base or the minimum section required by the City of Carlsbad, whichever is more, may be considered for initial planning phase cost estimating purposes only for the on-site asphalt paving surfaces outside public and private right-of-way (not for construction). Final pavement sections will depend on the actual R-value test results performed on finish subgrade soils, design TI, and approval of the City of Carlsbad. All design sections should be confirmed and/or revised as necessary at the completion of rough pavement subgrade preparations. Revised pavement sections should be anticipated. Base materials should be compacted to a minimum 95% of the corresponding maximum dry density (ASTM D-1557). Subgrade soils beneath the asphalt paving surfaces should also be compacted to a minimum 95% of the corresponding maximum dry density within the upper 12 inches. VINJE & MIDDLETON ENGINEERING, INC. 1 2450 Vineyard Avenue Escondido, California 920294229 Phone (760) 743-1214 Mr. Sjirk Zijistra September 25, 2006 Page 11 PCC Paving: Residential PCC driveways and parking supported on very low to low expansive (expansion index less than 51) subgrade soils should be a minimum of 5% inches in thickness, reinforced with #3 reinforcing bars at 16 inches on centers each way, placed at mid-height in the slab. Subgrade soils beneath the PCC driveways and parking should also be compacted to a minimum 95% of the corresponding maximum dry density. Provide "tool joint" or "softcut" contraction/control joints spaced 10 feet on center (not to exceed 15 feet maximum) each way. Tool or cut as soon as the slab will support weight and can be operated without disturbing the final finish which is normally within 2 hours after final finish at each control joint location or 150 psi to 800 psi. Tool or softcuts should be a minimum 1-inch in depth but should not exceed I Y4-inches deep maximum. In case of softcut joints, anti-ravel skid plates should be used and replaced with each blade to avoid spalling and raveling. Avoid wheeled equipments across cuts for at least 24 hours. General Paving: Base layer and subgrade soils should be tested for proper moisture and the specified compaction levels, and approved by the project geotechnical consultant prior to the placement of the base or asphalt/PCC finish surface. Base section and subgrade preparations per structural section design, will be required for all surfaces subject to traffic including roadways, travelways, drive lanes, driveway approaches and ribbon (cross) gutters. Driveway approaches within the public right-of-way should have 12 inches subgrade compacted to a minimum 95% compaction levels, and provided with 95% compacted Class 2 base section per the structural section design. Base layer under curb and gutters should also be compacted to a minimum 95% Compaction levels. Base section may not be required under curb and gutters, and sidewalks in the case of very low expansive subgrade soils (expansion index less than 21). Appropriate recommendations should be given in the final as-graded compaction report. VII. GENERAL RECOMMENDATIONS The minimum foundation design and steel reinforcement provided herein are based on soil characteristics and are not intended to be in lieu of reinforcement necessary for structural considerations. Adequate staking and grading control is a critical factor in properly completing the recommended remedial and site grading operations. Grading control and staking should be provided by the project grading contractor or surveyor/civil engineer, and VJ;E & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue Escondido, California 92029-1229 • Phone (760) 743-1214 Mr. Sjirk.Zijlstra September 25, 2006 Page 12 is beyond the geotechnical engineering services. Inadequate staking and/or lack of grading control may result in unnecessary additional grading which will increase construction costs. Footings located on or adjacent to the top of slopes should be extended to a sufficient depth to provide minimum horizontal distance of 7 feet or one-third of the slope height, whichever is greater (need not exceed 40 feet maximum) between the bottom edge of the footing and face of slope This requirement applies to all improvements and structures including fences, posts, pools, spas, etc. Concrete and AC improvements should be provided with a thickened edge to satisfy this requirement. Open or backfihled trenches parallel with a footing shall not be below a projected plane having a downward slope of 1-unit vertical to 2 units horizontal (50%) from a line 9 inches above the bottom edge of the footing, and not closer than 18 inches form the face of such footing. Where pipes cross under-footings, the footings shall be specially designed. Pipe sleeves shall be provided where pipes cross through footings or footing walls, and sleeve clearances shall provide for possible footing settlement but not less than 1- inch all around the pipe. Foundations where the surface of the ground slopes more than 1-unit vertical in 10 units horizontal (10% slope) shall be level or shall be stepped so that both top and bottom of such foundations are level. Individual steps in continuous footings shall not exceed 18 inches in height, and the slope of a series of such steps shall not exceed 1-unit vertical to 2-units horizontal (50%) unless otherwise specified. The steps shall be detailed on the structural drawings. The local effects due to the discontinuity of the steps shall also be considered in the design of foundations as appropriate and applicable. Expansive clayey soils should not be used for backfilhing of any retaining structure. All retaining/basement walls should be provided with a 1:1 wedge of granular, compacted backfill measured from the base of the wall footing to thefinished surface, and a well constructed back drainage system as shown on the enclosed Plate 1. B. All underground utility and plumbing trenches should be mechanically compacted to a minimum 95% of the maximum dry density of the soil unless otherwise specified. Care should be taken not to crush the utilities or pipes during the compaction of the soil. Non-expansive, granular backfill soils should be used. Trench backfill materials and compaction beneath pavements within the public right-of-way shall conform to the City of Carlsbad requirements. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue Escondido, California 92029-1229 • Phone (760) 743-1214 Mr. Sjirk Zijistra September 25, 2006 Page 13 Site drainage over the finished pad surfaces should flow away from structures onto the street in a positive manner. Care should be taken during the construction, improvements, and fine grading phases not to disrupt the designed drainage patterns. Roof lines of the buildings should be provided with roof gutters. Roof water should be collected and directed away from the buildings and structures to a suitable location. Final plans should reflect preliminary recommendations given in this report. Final foundations and grading plans may also be reviewed by the project geotechnical consultant for conformance with the requirements of the geotechnical investigation report outlined herein. More specific recommendations may be necessary and should be given when final grading and architectural/structural drawings are available. All foundation trenches should be inspected to ensure adequate footing embedment and confirm competent bearing soils. Foundation and slab reinforcements should also be inspected and approved by the project geotechnical consultant. The amount of shrinkage and related cracks that occurs in the concrete slab-on- grades, flatworks and driveways depend on many factors the most important of which is the amount of water in the concrete mix. The purpose of the slab reinforcement is to keep normal concrete shrinkage cracks closed tightly. The amount of concrete shrinkage can be minimized by reducing the amount of water in the mix. To keep shrinkage to a minimum the following should be considered: * Use the stiffest mix that can be handled and consolidated satisfactorily. Use the largest maximum size of aggregate that is practical. For example, concrete made with %-inch maximum size aggregate usually requires about 40- lbs. more (nearly 5-gal.) water per cubic yard than concrete with 1-inch aggregate. * Cure the concrete as long as practical. The amount of slab reinforcement provided for conventional slab-on-grade construction considers that good quality concrete materials, proportioning, craftsmanship, and control tests where appropriate and applicable are provided. A preconstruction meeting between representatives of this office, the property owner or planner, city inspector, as well as the grading contractor/builder is recommended in order to discuss grading/construction details associated with site development. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue• Escondido, California 92029-1229 • Phone (760) 743-1214 Mr. Sjirk Zijistra September 25, 2006 Page 14 VIII. LIMITATIONS The conclusions and recommendations provided herein have been based on available data obtained from the review of pertinent reports and plans, subsurface exploratory excavations as well as our experience with the soils and formational materials located in the general area. The materials encountered on the project site and utilized in our laboratory testing are believed representative of the total area; however, earth materials may vary in characteristics between excavations. Of necessity we must assume a certain degree of continuity between exploratory excavations and/or natural exposures. It is necessary, therefore, that all observations, conclusions, and recommendations be verified during the grading operation. In the event discrepancies are noted, we should be contacted immediately so that an inspection can be made and additional recommendations issued if required. The recommendations made in this report are applicable to the site at the time this report was prepared. It is the responsibility of the owner/developer to ensure that these recommendations are carried out in the field. It is almost impossible to predict with certainty the future performance of a property. The future behavior of the site is also dependent on numerous unpredictable variables, such as earthquakes, rainfall, and on-site drainage patterns. The firm of VINJE & MIDDLETON ENGINEERING, INC., shall not be held responsible for changes to the physical conditions of the property such as addition of fill soils, added cut slopes, or changing drainage patterns which occur without our inspection or control. The property owner(s) should be aware that the development of cracks in all concrete surfaces such as floor slabs and exterior stucco are associated with normal concrete shrinkage during the curing process. These features depend chiefly upon the condition of concrete and weather conditions at the time of construction and do not reflect detrimental ground movement. Hairline stucco cracks will often develop at window/door corners, and floor surface cracks up to 1/8-inch wide in 20 feet may develop as a result of normal concrete shrinkage (according to the American Concrete Institute). This report should be considered valid for a period of one year and is subject to review by our firm following that time. If significant modifications are made to your tentative development plan, especially with respect to the height and location of cut and fill slopes, this report must be presented to us for review and possible revision. This report is issued with the understanding that the owner or his representative is responsible to ensure that the information and recommendations are provided to the project architect/structural engineer so that they can be incorporated into the plans. ViNJE & MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue Escondido, California 92029-1229 • Phone (760) 743-1214 No. 2= CER'flPIED * ENGINEERING GEOLOGIST Exp. 5-31-07 0 01Z * Mr. Sjirk Zijlstra September 25, 2006 Page 15 The project soils engineer should be provided the opportunity for a general review of the project final design plans and specifications in order to ensure that the recommendations provided in this report are property interpreted and implemented. The project soils engineer should also be provided the opportunity to verify the foundations prior the placing of concrete. If the project soils engineer is not provided the opportunity of making these reviews, he can assume no responsibility for misinterpretation of his recommendations. Vinje & Middleton Engineering, Inc., warrants that this report has been prepared within the limits prescribed by our client with the usual thoroughness and competence of the engineering profession. No other warranty or representation, either expressed or implied, is included or intended. Once again, should any questions arise concerning this report, please do not hesitate to contact this office. Reference to our Job #03-348-P will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. %Tt4 Dennis Middleton CEG #980 S. ,iehdi S. Shariat ROE #46174 Steven J. Melzer CEG#2362 Distribution: Addressee (5) Enclosures: Plate I Appendices A-C c:ljtImyfiles/06updates/03-348-P C 98 * CERTIFIED * ENGINEERING Oi No. 46174 r Exp. 12-31-06 CIVIk- F\* VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 RETAINING WALL DRAIN DETAIL Typical - no scale - drainage .: :. : '•'[/' " . : Granular, non-expansive backfill. Compacted,/ etitq •: .:. ________ Competent, approved soils or bedrock Waterproofing Perfoated drain pipe Filter Material; Crushed rock (wrapped in filter fabric) or Class 2 Permeable Material (see specifications below) '5P FQRCALTRN5. L4S 2 ER iaaie MATERIAL U.S. STANDARD r SIEE. .' - %PASSING. r -. -c .314 :: •. 00 .40400 .N8. r3D ..545 - . • t_.' - -.. :; .i ?. -' SandE,t75',' CONSTRUCTION SPECIFICATIONS: Provide granular, non-expansive backfill soil in 1:1 gradient wedge behind wall. Compact backfill to minimum 90% of laboratory standard. Provide back drainage for wall to prevent build-up of hydrostatic pressures. Use drainage openings along base of wall or back drain system as outlined below. Backdraln should consist of 4" diameter PVC pipe (Schedule 40 or equivalent) with perforations down. Drain to suitable outlet at minimum 1%. Provide 3/4'- 11R crushed gravel filter wrapped in filter fabric (Mirafi 140N or equivalent). Delete filter fabnc wrap If Caifrans Class 2permeable material is used. Compact Class 2 material to minimum 90% of laboratory standard. Seal back of wall with waterproofing in accordance with architect's specifications. Provide positive drainage to disallow ponding çf water above walL Lined drainage ditch to minimum 2% flow away from wall is recommended. * Use 11A cubic foot per foot with granular backfill soll and 4 cubic foot per foot if expansive backfill soil is used. VINJE & MIDDLETON ENGINEERING, INC. PLATE 1 APPENDIX A PNTrTN1PPP TNT(. 2450 Vineyard Avenue Job #03-348-P Escondido, California 92029-1229 Phone (760) 743-1214 Fax (760) 739-0343 July 14, 2006 Zijistra Architecture Attn: Mr., Sjirk Zijistra 731 South Highway 101 Suite I L Solana Beach, California 92075 FOUNDATION PLAN REVIEW, PROPOSED THREE-STORY TWIN HOMES, LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD, CALIFORNIA We have received and reviewed the project foundation plans and details for the above- referenced two units three-story residential building construction, prepared by Zijistra Architecture (last dated June 12, 2006). According to the project plans, the project building will be supported on 15 inches square prestressed concrete driven piles and grade beam type foundations. The lower floors will be designed structural slabs spanning over the grade beams. Based on our review of drawings made available to us, and from a geotechnical engineering point of view, project foundation plans/details are in substantial compliance with our report entitled "Preliminary Geotechnical Investigation, Lot 31, Tract 5162, Cove Drive, Carlsbad, California," Job #03-348-P, dated March 3, 2004. The following comments are appropriate and should be considered and/or incorporated into the final foundation plans and implemented during the construction phase wherever appropriate and applicable: The referenced Preliminary Geotechnical Investigation Report, dated March 3, 2004, should be considered a part of the project foundation plans. 2. Based upon the results of the tested soil sample, the amount of water soluble sulfate (SO4) in the soil was found to be 0.268 percent by weight which is considered severe according to the California Building Code Table No. .19-A-4. Consequently, the project site is classified as corrosive, and corrosion mitigation should be implemented and incorporated into the design of project structures and improvements as appropriate. A corrosion engineer may also be consulted in this regard. Portland cement Type V (minimum f'c = 4500 psi, maximum water cement ratio = 0.45) or as determined by the project corrosion/structural engineer, should be considered. Mr. Sjirk Zijfstra July 14, 2006 Page 3. All construction works should be continuously inspected and tested as necessary and appropriate. Special geotechnical engineering inspections will be required for the pile driving operations. The project contractor shall prepare and submit to the architect/engineer of work, detailed pile data and plant certifications as well as delivering, staging, driving methods and hammer data (including make and model number) for review and approval prior to the initiation of actual works. A table listing all construction works requiring special inspections may be included in the project plans. Engineering construction inspections and test results should be presented in written field and final reports. All design recommendations should be further field verified, confirmed, or revised if necessary. If you have any questions or need clarification, please do not hesitate to contact the undersigned. Reference to our Job #03-348-P will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. hdi S. Shanat 46174 #46174 Exp. 12-31-08 SMSSTjt Distribution: Addressee (2, fax) c:ljt/myfi1es/06-updates,etc. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue Escondido, California 92029-1229 • Phone (760) 743-1214 UTILITY VAULT"m c_., ' WORMATION PRESTRESSED CONCRETE iPLUS Pile Size and Shape is thee a p%n1iTfnm coQcetC strength 5pecificd? t'c __psi @28 d4y8 • Provida Pie LOadS 35 St1n2gth level (I'actored Loads, 1999 USC) Wbzt uv she Loads? Pvide total rrrm loads chat our pile cns secon will s Include any P.Delta M04=0 due to iew1ly unsupported lengths if applicable. Sbaw brkdou for Dead, Live and Ssmir, itivallabie Dead Live EorW Tol. - -- - Ailal Ceanprseton (kipe or toes) Aiial Tenaton (kips or toes) Bcndliig Mawc*t (foot-lçips) Sbear ps) Specify Load Combinations to be designed for Scxuiiug nd Compression 0 &nding and Tenon 0 Oth,dcacrlbc__________________ flexural Length in Yeet - (auzh Moment or Ddectiou DIaam) NOTE: The above loads and'c mbitzadous should be shown on the Stncnal Drawings Wthe loads axe net shown, ibis fonu can be scm to the Sirucuanl Engineer to be completed. Soils Reporca are good background iufntiadon but should nor be used to obtan actual psic loads Actual pile loads and combãianoris come fim the structure itself (and beace Sucual nginees Drawings). (O9r5oS8* FU (909) 350-0620 FOUNDATION PLE PILE, INC. FqsDAfl45 4FF REOMAN AMa Pa 80* Ile? F01'4n CA 92304 Pzge2of 3 Customer Project_ Pile Size Are there any specified Stnthfluat t)rawthg ])euIs showing the following: Concrete cover over Spiral Sirud quandty, size and localloit Reinforcing bar length, size, location and quantity s_I S2C and spacing Dowelnbe Strand Extensions u Rebar let Tubes For boxes checked above please attach a copy ofStnctural Drawing fr.tai1s If the imfonnanon is not in the Stiucwzah Drawing details please attach copies of relevant portions of spci1icat30n5 or a sketch of what you or your customer want. How much extra length is required at the top of the pile to allow for cut ofL? Any Special Coatings required on spiral, strand or rebar? Pintse describe; See Page 3 PaSp 3 of 3 NOTE: The above information is a minünwa that we require to design your presresscd concrete pile. Please sign and date the bottom alibis page to show this is what you want Basod on the above information we will engineer your pile and provide y9a with a drawing for tnaJ approvaL Wemnat have you sign the drawing before we chedule production- If Calculationsand/or a Conczere Miz Desi2n are Tequired by a 14stered Civil Engineer these will also be provided with your drawing. The cost of Eruneering is included in our quote. M however, d= are later changes to the inaticn given on this form, additional engineeting costs will be charged at the Mowing raias Rgistered Engineer, S120.001bour CAD Operator $50.001hoir Changes to this information will also result in delays to the subminal, production and dclivety scbuWlea. Please give the utcma on this form careful consideration. Cusiøinecs who provide accurate information up onr will obviously receive prodicts sooner than those who make changes. otncrSipature Data Contractor Name__________________________ Jab Name lob Location For liital Use Only; dc Noc____ MD QCM - APPENDIX B Preliminary Geotechnical Investigation Lot 31, Tract 5162, Cove Drive Carlsbad, California March 3, 2004 Prepared For: MR. JERZY J. LEWAK c/o Nisus Software, Inc. 107 South Cedros Avenue, Suite B Solana Beach, California 92075 Prepared By: VINJE & MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue, Suite 102 Escondido, California 92029 Job #03-348-P P.N1CTNTPPP 2450 Vineyard Avenue Job #03-348-P Escondido, California 92029-1229 Phone (760) 7434214 Fax (760) 739-0343 March 3, 2004 Mr. Jerzy J. Lewak do Nisus Software, Inc. 107 South Cedros Avenue, Suite B Solana Beach, California 92075 PRELIMINARY GEOTECHNICAL INVESTIGATION, LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD, CALIFORNIA Pursuant to your request, Vinje and Middleton Engineering, Inc., has completed the Preliminary Geotechnical Investigation Report for the above-referenced project site. The following report summarizes the results of our research and review of pertinent geotechnical maps and reports, subsurface field investigation and soil sampling, laboratory testing, engineering analyses and provides conclusions and construction recommendations for the proposed development as understood. From a geotechnical engineering standpoint, it is our opinion that the site is considered suitable for the support of the proposed duplex condominium building with the associated improvements, provided the recommendations presented in this report are incorporated into the design and construction of the project. The conclusions and recommendations provided in this study are consistent with the indicated site geotechnical conditions and are intended to aid in preparation of final development plans and allow more accurate estimates of the construction costs. If you have any questions or need clarification, please do not hesitate to contact this office. Reference to our Job #03-348-P Will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. I f CEG98O I * I CERTIFIED I * \ ENGINEERING I 15eri-nis Middleton CEG#980 OP CAU DMTjt TABLE OF CONTENTS PAGE NO. I. INTRODUCTION . I II. SITE DESCRIPTION . I III. PROPOSED DEVELOPMENT ........................................j IV. SITE INVESTIGATION ..............................................I V. GEOTECHNICAL CONDITIONS .......................................2 Earth Materials ..................................................2 Groundwater ...................................................2 Slope Stability .................................................2 D.. Faults I Seismicity ..............................................3 Geologic Hazards and Liquefaction Potential ........................5 Laboratory Testing I Results ......................................5 VI. CONCLUSIONS ...................................................9 VII. RECOMMENDATIONS ..............................................10 VIII. LIMITATIONS ...................................................12 TABLE NO. FaultZone ...........................................................I Site Seismic Parameters ..............................................2 SoilType ..............................................................3 Maximum Dry Density and Optimum Moisture Content .....................4 Moisture-Density Test (Undisturbed Ring Samples) ........................5 Expansion Index Test ..................................................6 Direct Shear Test .....................................................7 Grain Size Analysis ...................................................8 Amount of Material in Soils Finer than the No. 200 Sieve .....................9 Liquid Limit, Plastic Limit and Plasticity Index ...........................10. SulfateTest .........................................................11 TABLE OF CONTENTS (continued) PLATE NO. Regional Index Map .................................................. SitePlan ...........................................................2 Architectural Site Plan ................................................3 Architectural Building Section ..........................................4 Boring Logs (with key) ...............................................5-6 Fault - Epicenter Map .................................................7 Corrected N-values & Liquefaction Safety Factor Graphs .................8-9 Grain Size Analysis .................................................10 Engineering Design Information by Foundation Pile, Inc.......................................Appendix A PRELIMINARY GEOTECHNICAL INVESTIGATION LOT 31, TRACT 5162, COVE DRIVE CARLSBAD, CALIFORNIA INTRODUCTION The property investigated herein is a small bay-side lot off of Agua Hedionda, near the coast in the City of Carlsbad. The approximate site location is depicted on a Regional Index Map enclosed with this report as Plate 1. We understand that the site is planned for the support of a duplex condominium structure which will occupy much of the lot surface. Consequently, this study was initiated to determine geologic and soils conditions beneath the propeity and their influence upon the planned development. Deep test hole borings, soil sampling and testing were among the activities conducted in connection with this effort which has resulted in the design and foundation recommendations presented herein. SITE DESCRIPTION The project site is a small, level lot between two developed buildings on either side. Cove Drive provides access and marks the front (western) boundary. A small graded and rock- lined slope marks the rear (eastern) boundary which descends approximately 8 feet into the lagoonal waters. The lot surface soils support a light cover of native grasses. Site drainage is indistinct with no evidence of scouring or run-off erosion. Details of site conditions are shown on a Site Plan enclosed herein as Plate 2 Ill. PROPOSED DEVELOPMENT An Architectural Site Plan prepared by Zijlstra Architecture, and property layout are depicted on Plate 3. An architectural building section is also included herein as Plate 4. No grading is planned and finish grades are likely to be at or very near the existing ground surfaces. The use of conventional wood-frame with exterior stucco buildings supported on driven prestressed concrete pile foundations with raised structural floor type construction is also anticipated. The rear patio and the driveway will consist of flexible interlocking concrete payers set in sand. The project utilities/plumbing pipes will be suspended from the structural slab/grade beams. IV. SITE INVESTIGATION Subsurface conditions at the project lot were chiefly determined from the excavation of 2 test boring drilled with a truck-mounted rotary drill. The borings were logged by our project geologist who also retained soil/rock samples for laboratory analysis. Test boring locations are shown on Plate 2. Logs of the borings are enclosed herein as Plates 5 and 6. Laboratory test results are summarized in a following section. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue Escondido, California 92029-1229 Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 2 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 V. GEOTECHNICAL CONDITIONS The project site is situated upon level terrain created in the 1960's by placing imported fill soils over natural lagoonal areas adjacent to Agua Hedionda. Grading records for engineering inspections and compaction testing of the existing fills are unavailable. Earth Materials The following earth materials underlie the project site: Fill - Imported fill soils directly underlie the project site to an approximate depth of 15 feet. The fill consists chiefly of clayey sands in a loose to very loose and moist to saturated condition overall. Lagoonal Deposit - Natural lagoonal soils underlie site the fills to significant depths. These soils consist of variable sequence of dark colored clayey and silty soils with sandy lenses that occur in a saturated and very soft to very loose condition. Bedrock - The site is underlain at depths by sedimentary bedrock units which characterize nearby hillside terrain. The rocks consist chiefly of sandy to clayey siltstone units found in a cemented and firm condition. Based upon test boring exposures, bedrock units occur at approximate depths of 50 feet below the existing lot surface. 11 Details of site earth materials are given on the enclosed Boring Logs, Plates 5 and 6. Engineering properties are additionally defined in a following section. Groundwater Subsurface groundwater characterizes the project soil section at depths of 5 to 7 feet below existing lot surfaces. The water reflects lagoonal water which has saturated the underlying soils. The indicated levels are expected to fluctuate slightly with changing tide levels. Slope Stability A small graded slope descends into the lagoon along the north property boundary. The slope is a 2:1 gradient embankment which is provided with large rock rip-rap facing. No evidence of instability is apparent within the project slope. VINJE & M:DDLETON ENGINEERING, INC. 1 2450 Vineyard Avenue Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 3 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 D. Faults I Seismicity Faults dr significant shear zones are not indicated on or near proximity to the project site. As with most areas of California, the San Diego region lies within a seismically active zone; however, coastal areas of the county are characterized by low levels of seismic activity relative to inland areas to the east. During a 40-year period (1934-1974), 37 earthquakes were recorded in San Diego coastal areas by the California Institute of Technology. None of the recorded events exceeded a Richter magnitude of 3.7, nor did any of the earthquakes generate more than modest ground shaking or significant damages. Most of the recorded events occurred along various offshore faults which characteristically generate modest earthquakes. Historically, the most significant earthquake events which affect local areas originate along well known, distant fault zones to the east and the Coronado Bank Fault to the west. Based upon available seismic data, compiled from California Earthquake Catalogs, the most significant historical event in the area of the study site occurred in 1800 at an estimated distance of 10 miles from the project area. This event, which is thought to have occurred along an off-shore fault, reached an estimated magnitude of 6.5 with estimated bedrock acceleration values of 0.128g at the project site. The following list represents the most significant faults which• c6mmonly impact the region. Estimated ground acceleration data compiled from Digitized California Faults (Computer Program EQ FAULT VERSION 3.00 updated) typically associated with the fault is also tabulated: TABLE I FT s'i• - ' Rose Canyon fault 5 miles 0.244g Newport-Inglewood fault 6,1 miles 0.220g Corcnado Bank fault 21.2 miles 0.184g Els'nore fault 24.1 miles 0. 142g The location of significant faults and earthquake events relative to the study site are depicted on a Fault - Epicenter Map enclosed herein as Plate 7. VINJE & MIDDLETON ENGINEERING, INC. 0 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 7434214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 4 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 More recently, the number of seismic events which affect the region appears to have heightened somewhat. Nearly 40 earthquakes of magnitude 3.5 or higher have been recorded in coastal regions between January 1984 and August 1986. Most of the earthquakes are thought to have been generated along offshore faults. For the most part, the recorded events remain moderate shocks which typically resulted in low levels of ground shaking to local areas. A notable exception to this pattern was recorded on July 13, 1986. An earthquake of magnitude 5.3 shook County coastal areas with moderate to locally heavy ground shaking resulting in $700,000 in damages, one death, and injuries to 30 people. The quake occurred along an offshore fault located nearly 30 miles southwest of Oceanside. A series of notable events shook County areas with a (maximum) magnitude 7.4 shock in the early morning of June 28, 1992. These quakes originated along related segments of the San Andreas Fault approximately 90 miles to the north. Locally high levels of ground shaking over an extended period of time resulted; however, significant damages to local structures were not reported. The increase in earthquake frequency in the region remains a subject of speculation among geologists; however, based upon empirical information and the recorded seismic history of County areas, the 1986 and 1992 events are thought to represent the highest levels of ground shaking which can be expected at the study site as a result of seismic activity. In recent years, the Rose Canyon Fault has received added attention from geologists. The fault is a significant structural feature in metropolitan San Diego which includes a series of parallel breaks trending southward from La Jolla Cove through San Diego Bay toward the Mexican border. Test trenching along the fault in Rose Canyon indicated that at that location the fault was last active 6,000 to 9,000 years ago. Thus, the fault is classified as "active" by the State of California which defines faults that evidence displacement in the previous 11,000 years as active. More active faults (listed on the preceding page) are considered most likely to impact the region during the lifetime of the project. The faults are periodically active and capable of generating moderate to locally high levels of ground shaking at the site. Ground separation as a result of seismic activity is not expected at the property. For design purposes, site specific seismic parameters were determined as part of this investigation in accordance with the Uniform Building Code. The following parameters are consistent with the indicated project seismic environment and may be utilized for project design work: VINJE & MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue • Escondido, California 920294229 1 Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION IPAGE 5 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 TABLE 2 Site Spit Pme isic Seismiq StSmIc Site - SeIsrnJcRosponse Coeffictnts '- - 4 SF 1 4 1 0.4 1 B 1 1.0 1.1 I 0.66 J 1.92 I 1.164 I 0.233 According to Chapter 16, Division IV of the 1997 Uniform Building Code. 11 11 Site probabilistic estimation of peak ground acceleration was also evaluated using the FRISKSP VERSION 4.00 UPDATE (T. Blake, 2000) computer program. Based on Boore et.al (1997), a 10 percent probability of exceedance in 50 years was estimated to generate a site specific peak ground acceleration of 0.3509. The result was obtained from the corresponding probability of exceedance versus acceleration curve. Geologic Hazards and Liquefaction Potential Based on our site specific geotechnical study, the most significant geologic hazard at the project site will be those associated with liquefaction and secondary ground rupture/movements which may be initiated by a major seismic event along a distant active fault. Significant slopes are not present at the project nor is site development expected to construct major graded slope conditions. A soil profile was modeled based on the new boring data and analyzed using the LIQUEFY2 VERSION 1.5 UPDATE (T. Blake, 1998) computer program. Based upon our analysis and assumptions using a design site specific peak ground acceleration of 0.350g, design earthquake magnitude of 7.5 and corrected N- values, saturated site fills and natural lagoonal deposits are highly liquefiable (safety factors less than 1.0). Corrected N-values and liquefaction safety factor graphs are included with this report as Plates 8 and 9. Laboratory Testing I Results Earth deposits encountered in our exploratory test excavations were closely examined and sampled for laboratory testing. Based upon our test trench data and field exposures site soils have been grouped into the following soil types: VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION . PAGE 6 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 TABLE 3 DçdØtE r 1 brown clayey to silty sand (Fill) 2 dark brown to grey fine to medium sand with a trace of clay (fill) 3 grey to brown silty to sandy clay/clayey silt (Lagoonal deposit, fill) 4 tan medium to coarse sand (Lagoonal deposit) 5 dark brown silty to clayey sand (Lagoonal deposit) 6 olive fine sandy to clayey siltstone (Formational rock) The following tests were conducted in support of this investigation: Standard Penetration Tests: Standard penetration tests (SPT) were performed at the time of bore hole drilling in accordance with the ASTM standard procedure D-1586, using a mechanical drive hammer. The procedure consisted of a standard 51 MM outside diameter sampler, 457 MM in length and 35 MM in inside diameter using 5 foot long AW drill rods. The bore hose was 200 MM (8 inches) in diameter and water was added for bore hole support. The test results are indicated at the corresponding locations on the Boring Logs. Maximum Dry Density and Optimum Moisture Content: The maximum dry density and optimum moisture content of Soil Type 1 was determined in accordance with ASTM D-1557. The test result is presented in Table 4. TABLE 4 PF IN 1~ 1 1 130.4 11.1 Moisture-Density Test (Undisturbed Ring Samples): In-place dry density and moisture content of representative soil deposits beneath the site were determined from a relatively undisturbed ring sample using the weights and measurements test method. The test result is presented in Table 5 and tabulated on the enclosed Boring Logs (Plates 5-6). VINJE & MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue Escondido, California 92029-1229 1 Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 7 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 TABLE 5 SmpIe OW Typo:. FM4' Qsture', bQItt ,Fiel W.d Dry Ief!S1tY.. ' .pc.;• . ax Dl Rajio Of In $acDry Detsity'ro Max. Dry , Dènt' B-I @3' J 1 5.8 - 130.4 loose disturbed sample *Designated as relative compaction for structural fills. Required relative compaction for structural fill is 90% or greater. * Expansion Index Test: One expansion index test was performed on a representative sample of Soil Typo 1 in accordance with the Uniform Building Code Standard 18-2. The test result is presented in Table 6. TABLE 6 .1 - ... ...SamjO j ftL4 J' _tou I 9.9 50.8 17.9 25 low (w) = moisture content in percent Direct Shear Test: One direct shear test was performed on a representative sample of Soil Type 1. The prepared specimen was soaked overnight, loaded with normal loads of 1, 2, and 4 kips per square foot respectively, and sheared to failure in an undrained condition. The test result is presented in Table 7. TABLE 7 4 t ç.. iot Aia't 1..Qatt, juith3' ' t-pb ei I_B-i t 2 J 1 I remolded to 90% of Yin % wopt 130.4 31 185 I Grain Size Analysis: Grain size analyses were performed on representative samples of Soil Types 3 and 4. The test results are presented in Table 9 and graphically illustrated on the enclosed Plate 10. VNJE & MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue Escondido, California 920294229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 8 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 TABLE 8 Sieve Sizei ..#i0. 440 ________ Location Soil Type .1 B-I t 25' 3 100 99 ' 9 97 - 90 B-I © 35 4 3 B-2@15' :.f•'-..'-99_.. _____ _____ Amount of Material in Soils Finer Than the No. 200 Sieve: The amount of material in soils finer than No. 200 sieve tests were performed on representative selected samples of foundation bearing and pavement subgrade soils in accordance with the ASTM D-1140. The test results are presented in Table 9. TABLE 9 iiFIi b :f.èñtMäthiIaT I '. aftOvWashñg ' Fier OO ' - - B-i @2' 751.2 466.7 38 SMISC B-i @ 7W 226.9 137.4 40 Sc B-I © 15' 256.7 20.9 92 ML/CL Ir—B-i @45' 100.0 72.2 28 SM Liquid Limit. Plastic Limit and Plasticity Index: Liquid limit, plastic limit and plasticity index tests were performed on representative samples of Soil Types 3 and 4 in accordance with the ASTM 0-4318. The test results are presented in Table 10. TABLE 10 Fla I V`11_1 B-I@15' 3 59 27 32 B-I © 35' 4 - - non-plastic VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue Escondido, California 92029-1229 • Phone (760) 7434214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 9 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 9. Sulfate Test: One sulfate test was performed on a representative sample of Soil Type I in accordance with the California Test 471. The test result is presented in Table 11. TABLE II 'Y. Lçcjbt -apIe SoiPlype' We!gt) -In-o1% by B-I @ 2 1 0.268 VI. CONCLUSIONS Based upon the foregoing investigation, development of the project lot for residential purposes is feasible from a geotechnical viewpoint. However, the site is underlain by a thick section of highly liquefiable loose and saturated soil deposits which will require special geotechnical engineering development techniques. The following factors are unique to the property and will most impact its development from a geotechnical viewpoint: Liquefaction is the most significant geotechnical concern at the project property. Secondary affects such as seismically induced settlements, sand boils, ground spreading and lurching also remain a major concern at the study property. The underlying loose and saturated fills and lagoonal deposits are also highly compressible. Project compressible soils are not suitable for foundation support. The upper fill soil above the water table are susceptible to collapse in their present conditions. However, remedial grading is not planned and project utility/plumbing pipes will be suspended from the structural slab/grade beams, and flexible interlocking payers will be used for the rear patio and driveway construction. In the absence of remedial grading removal and re-compaction, continued repairs of on-grade site improvements supported on the existing soils should be anticipated. The project property is not suitable for the support of shallow conventional foundations, and cut-fill and remedial grading is not planned. Deep prestressed driven concrete pile foundations and structural floors should be used as recommended in the following sections. Competent formational bedrock units occur at depths of approximately 50 feet below the existing lot surfaces which could suitably support driven concrete pile foundations. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, Ca1ifonia 92029-1229 • Phone (760) 7434214 PRELIMINARY GEOTECHNI CAL INVESTIGATION PAGE 10 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 Groundwater was encountered in both exploratory boring excavations at the depth of approximately 5 to 7 feet at the time of our field investigation. Groundwater conditions at the project site is expected to seasonally fluctuate and may impact foundation constructions. Site upper soils include some clay bearing deposits. Finish grade soils are expected to consist of clayey to silty sand (SM/SC) with low to very low expansion potential (expansion index less than 51). VII. RECOMMENDATIONS Recommendations provided herein are consistent with the indicated project conditions and are intended to preclude site adverse geotechnical factors impacting the future building structures. The following may be considered for site development and foundation designs: Cut-fill or remedial grading is not planned. Prestressed driven pile foundations will be used for support of the building. The rear patio and the driveway will consist of flexible interlocking concrete payers set in sand. The project utilities/plumbing pipes will also be suspended from the structural slab/grade beams. Pile foundations should be driven to adequate depths into the underlying formational bedrock bearing stratum by approved impact pile hammers. Actual pile foundations should be designed by the project structural engineer. However, the following geotechnical factors and soils design parameters associated with the structural pile design and installations are appropriate and should be considered where appropriate and applicable: The piles should consist of prestressed concrete piles proportioned, designed and manufactured to sustain the driving stresses and develop the design allowable pile capacity. A qualified contractor with experience with a similar project should be retained. A sample order form by Foundation Pile Inc., for engineering design information is enclosed herein as Appendix A. A minimum of 14 inches square prestressed concrete (f'c = 5000 psi) piles or greater may be considered. A point of fixity at a minimum of 3 feet below the contact with the formational units may be considered for determining the maximum moments. * The pile spacing shall not be closer than 2% times the pile diameter. Maximum spacing should be determined by the project structural engineer. * The capacity of pile groups will be less than the sum of individual piles in the same group and should be considered in the design. Actual supporting VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue Escondido, California 92029-1229 6 Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 11 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 capacity of piles driven closer than 8 times pile diameter, center to center, should be reduced using appropriate group efficiency formulas. * Piles should be driven into the underlying competent formational units until the design allowable pile capacity of 50 kips is developed. Formational units were encountered at the depth of 49 feet in our exploratory boring. Based on our analyses, design allowable pile capacity will be achieved when minimum 5 blows per inch of penetration for the last 3 inches of each pile in to the underlying formational units is indicated by the pile driving. Design blow counts in to the underlying formational units should be confirmed and/or revised as necessary by the project geotechnical consultant in the field based on the driving data obtained from the first pile. Pile lengths are not expected to exceed 60 to 65 feet maximum. Large rocks, cobble zones or hard and cemented layers which could influence pile driving through the site fills/lagoonal deposits were not indicated by our boring excavations where explored. Refer to the enclosed boring logs and gradation analyzes for establishing the characteristics of the underlying deposits for pile driving purposes. * Damages to the piles shall be avoided or minimized by squaring the driving head with the energy source. Appropriate pile-driving caps and/or cushions should be used. Driving should be sopped when the required driving resistance is encountered. Driving refusal is defined as 4 to 5 (approximately) blows for the last 14-inch of driving. * Actual pile capacities may vary based on the blow counts. The design allowable pile capacity, however, is for dead plus live loads and may be increased by one-third for wind and seismic loads. * Pile settlement should be limited to 4-inch maximum and less than 1A-inch differential due to liquefaction and load induced settlements. * Piles may be pre-drilled with an auger with a diameter less than the pile width. Pre-drilling, if used, shall be terminated a minimum of 5 feet above the final pile tip elevations. Pile driving should not damage or disturb the existing adjacent structures and improvements. * Pile driving shall be continuously inspected and monitored by the project geotechnical consultant. Added or modified recommendations should be given in the field based on the data obtained during the installations as appropriate. VINJE & MIDDLETON ENGINEERING, INC. 1 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 12 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 Grade beams and raised structural floors also designed by the project structural engineer should be considered for the planned buildings. Based upon the results of the tested soil sample, the amount of water soluble sulfate (804) in the soil was found to be 0.268 percent by weight which is considered severe according to the California Building Code Table No. 19-A-4. Portland cement Type V and minimum 4500 psi (f c) concrete should be used. Flexible interlocking concrete payers set in sand are considered for the rear patio, dnveway and on-site improvements. The payers may be placed over the existing subgrade soils, however, continued repairs and maintenance due to subgrade settlements should be anticipated. Final foundation and design plans should be provided to the project geotechnical consultant for review. Added or modified recommendations may be necessary based on the final design plans, and should be given at that time. VIII. LIMITATIONS The conclusions and recommendations provided herein have been based on available data obtained from pertinent reports and plans, subsurface exploratory excavations as well as our experience with the soils and formational materials boated in the general area. The materials encountered on the project site and utilized in our laboratory testing are believed representative of the total area; however, earth materials may vary in characteristics between excavations. Of necessity we must assume a certain degree of continuity between exploratory excavations and/or natural exposures. It is necessary, therefore, that all observations, conclusions, and recommendations be verified during the grading operation. In the event discrepancies are noted, we should be contacted immediately so that an inspection can be made and additional recommendations issued if required. The recommendations made in this report are applicable to the site at the time this report was prepared. It is the responsibility of the owner/developer to ensure that these recommendations are carried out in the field. It is almost impossible to predict with certainty the future performance of a property. The future behavior of the site is also dependent on numerous unpredictable variables, such as earthquakes, rainfall, and on-site drainage patterns. The firm of VINJE & MIDDLETON ENGINEERING, INC., shall not be held responsible for changes to the physical conditions of the property such as addition of fill soils, added cuts, or changing drainage patterns which occur without our inspection or control. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue Escondido, California 92029-1229 • Phone (760) 7434214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 13 LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD MARCH 3, 2004 The property owner(s) should be aware that the development of cracks in all concrete surfaces such as floor slabs and exterior stucco are associated with normal concrete shrinkage during the curing process These features depend chiefly upon the condition of concrete and weather conditions at the time of construction and do not reflect detrimental ground movement. Hairline stucco cracks will often develop at window/door corners, and floor surface cracks up to 1/8-IflCh wide in 20 feet may develop as a result of normal concrete shrinkage (according to the American Concrete Institute). This report should be considered valid for a period of one year and is subject to review by our firm following that time. If significant' modifications are made to your tentative development plan, especially with respect to the height and location of cut and fill slopes, this report must be presented to us for review and possible revision. Vinje & Middleton Engineering, Inc. warrants that this report has been prepared within the limits prescribed by our client with the usual thoroughness and competence of the engineering profession. No other warranty or representation, either expressed or implied, is included or intended. Once again, should, any questions arise concerning this report, please do not hesitate to contact this office. Reference to our Job #03-348-P will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. Dennis Middleton t * CEG#980 i S. Shariat 174 Steven J. Me RG #6953 DM/SMSS/SJM/jt r JAvo\ C.S o. 6953 31o5 J .4 Distribution: Addressee (1) Zijlstra Architecture (4) VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue Escondido, California 92029-1229 Phone (760) 743-1214 TOPOI map printed on 03/09/04 from "SenDiego.tpo' and Unthed,tpg" 11/.i1- W rK WUf iL/..1b/ W KeS \i 16 r , AGWNA ary ' .\• .5- 4S. - ' '.282 . •-7 '--(--' G - ., High - . .l S, t •S - . •t_s f / /3 ' - . h / • J\,j,,_j ~., Org- Sch . . Vellej / Hfgt* -.Iy \• -- :' .1 '•• •.•.(J 69 f I : :. •J-, 3 '•. 17 \/'i .S r1::3; 9 TIO : S.,. . 2 "-get. ' 0 •55,• / S / ) \ eservoir '3• I •, / / I . Sub - .3 • ,. \ \_' \ .33'3•'3-,'3'3••.3' \• •\ '3 ' S3 \ \ \ '3OS Farr - \i \ c \ B - • •"%'., \ .. 'S \ ) V . , V - V V - __________ -. •.• -. --- ----- - _—. ---'3. - % •.!s --------- L•-_b d V • • • ' . • 117.333330 W WGSB4 117,316670 W MLE TNVMN V PldomT0POI 01999 Pmdwdm SITE PLAN I-Of 31, TRACT 5162, COVE DRIVE, CARLSBAD, CALIF. 03-348-P Scale: 1"=;29 0 Location of test boring BOAT DOCK BAY Un SLOPE I PATiO 0 Ext. house VACANT LOT: Ext. house .1 PROPOSED I CONC. - I SIDEWALK - COVE DRIVE COVE DRIVE S. PLATE 2 FPQOW REAR T.&RO YAJW - t THRM STORY RE&PEWIAL UMDO PJLEX I •:; / ___(1 , / / __________ ,-E - I 2 c*pni.T \ L*PVGw& rLAwrm _ Ki RAMP !fi• TT1t1 I f \s11 __ _ -- - LSC.N'Wl& • ?ir1! I - - / C THREE STORY JDeNT1AL GOWQO DUPLEX CAURO ---- SITE PLAN am v. a..- '-f-f 7 PLATE 3 PLATE 4 4 PRIMARY DIVISIONS GROUP SECONDARY DIVISIONS SYMBOL —i GRAVELS CLEAN GW Well graded gravels, gravel-sand mixtures, little or no fines. GP Poorly graded gravels or gravel-sand mixtures, little or no fines. it 0 W GRAVELS W MORE THAN HALF (LESS THAN o OF COARSE 5% FINES) GRAVEL U)2 d FRACTION IS GM Silty gravels, gravel-sand-slit mixtures, non-plastic fines. LL Z LARGER THAN WITH GC Clayey gravels, gravel-sand-clay mixtures, plastic fines. uJ OZN NO. 4 SIEVE . FINES < < I SANDS CLEAN SW. Well graded sands, gravelly sands, little or no fines. Iw SANDS SP Poorly graded sands or gravelly sands, little or no fines. MORE THAN HALF (LESS THAN I OF COARSE 5% FINES) < l-_ O —' FRACTION IS SANDS SM Silty sands, sand-silt mixtures, non-plastic fines. o SMALLER THAN WITH 0 NO. 4 SIEVE - FINES SC Clayey sands, sand-dày mixtures, plastic fines. Ui ML Inorganic silts and very fine sands, rock flour, silty or clayey fine u.. N Lu i SILTS AND CLAYS sands or clayey silts with slight plasticIty. O - LIQUID UMIT IS CL Inorganic clays of low to medium plasticity, gravelly clays, sandy C/) LESS THAN 50% clays, silty clays, lean clays. CL Organic slits and organic silty clays of low plasticity. i u w __________________________________ i - 04 . MH Inorganic silts, micaceous or diatomaceous fine sandy or silty - wE0 SILTS AND CLAYS soils, elastic silts. CH zO<z Inorganic clays of high plasticity, fat clays. LuCCLu Z LIQUID UMIT IS GREATER THAN 50% OH . Organic clays of medium to high plasticity, organic silts. HIGHLY ORGANIC SOILS PT Peat and other highly organic soils. GRAIN SIZES U.S. STANDARD SERIES SIEVE CLEAR SQUARE SIEVE OPENINGS 200 40 10 4 3/4" 3" 12" SAND GRAVEL I I SILTS AND CLAYS j I ICOBBLES! BOULDERS FINE I MEDIUM COARSE FINE I COARSE J RELATIVE DENSITY ANDS, GRAVELS AND NON-PLASTIC SILTS BLOWS/FOOT VERY LOOSE 0 - 4 LOOSE 4-10 MEDIUM DENSE 10-30 DENSE 30-50 VERY DENSE OVER 50 CONSISTENCY CLAYS AND PLASTIC SILTS STRENGTH BLOWS/FOOT VERY SOFT 0-V.. 0-2 SOFT 'A-4 2-4 FIRM 4-1 4-8 STIFF 1-2 8-16 VERYST1FF 2-4 16-32 HARD OVER 4 OVER 32 Blow count, 140 pound hammer falling 30 inches on 2 inch O.D. split spoon sampler (ASTM D-1 586) Unconfined compressive strength per SOILTEST pocket penetrometer CL-700 V Sand Cone Test - Bulk Sample 246 = Standard Penetration Test (SPT) (ASTM 0-1 586) with blow counts per 6 inches Chunk Sample 0 Driven Rings 246 = California Sampler with blow counts per 6 inches VINJE &.MIDDLETON ENGINEERING, INC. 2450 Vineyard Ave., #102 Escondido, CA 92029-1229 KEY TO EXPLORATORY BORING LOGS Unified Soil Classification System (ASTM D-2487 PROJECT NO. I 'IA--'. KEY BORING LOG B-I DEPTH FT SAM'LE Drrnt1tv r USGS SYMBOL MOISTURE (%) DRY DENSITY (PCF) RELATIVE COMPACTION (%) -0- ...5 0 Clayey to silty sand. Brown color. Moist. LOose. Incomplete sample recovery at 3'. ST-1 SMISC 5.0 Clayey fine to medium sand with clay. Dark brown - to grey color. Saturated. Free water visible. Very loose. - SC _10- o Minimal sample recovery at 7W. No sample = : .s recovery at 10'. ST-2 LAGOONAL DEPOSIT: Clayey silt to silty clay. Grey to brown color. Locally sandy. Highly weathered. Very soft. High _15- 1 - plastic. Saturated. MUCH _20- At 25', sampler sunk to 18" underweight of drill - - -25-- stem. ST-3 ML Silt Dark grey color. Saturated. Plastic. Very soft. - - _30 - Some shell fragments. ST-3 SW Medium to coarse sand. Tan color. Saturated. - - Free water visible. Loose. ST-4 -. _____________________________ SM ' fo,s,s Silty sand. Clayey. Dark grey color. Medium - dense. ST-5 ML Fine sandy to clayey siltstone. Olive color. Moist. -40- - fBEDROCK: - - Cemented. Friable. - - ST-6 45- 457•_ E50 : End Test Boring at 56W. - -7.8,19 - - I j Groundwater at 5. Water added to aid drilling. - - Boring filled with bentonite. PROJECT: COVE DRIVE, CARLSBAD Bulk Sample a Ring Sample 0 Project No: 03-348-P Date Drilled: 8-14-03 -Logged By: SJM Truck-mounted rotary drill, 8" Hollow stem auger. Drill, Sample Method: 140 lb. Hammer. 30" mechanical drop. 5' AW rods. SPT Sample Groundwater V PLATE 5 VINJE & MIDDLETON ENGINEERING, INC. r BORING LOG 13-2 Description DRY RELATIVE DEPTH SAMPLE . USGS MOISTURE DENSITY COMPACTION FT SYMBOL (%) (PCF) (%) FILL: Silty sand. Trace of clay. Medium to coarse SM/SC - - grained. Very moist. Loose. ST-2 Clayey silt to silty clay. Dark brown color. Very - Hi moist. Very soft. Low plastic. - -.. MLJCL - - Becomes pale brown color below 10'. ST-3 End Test Boring at 16W. 20 Groundwater at 7'. Boring filled with bentonite. -25- -30 - -35- -40- _45- _50- I J Bulk Sample 0 PROJECT: COVE DRIVE, CARLSBAD Ring Sample 0 SPT Sample Project No: 03-348-P Date Drilled: 8-14-03Logged By: SUM Groundwater .. Truck mounted rotary drill, 8" Hollow Stem Auger. PLATE Drill, Sample Method: 140 lb. Hammer, 30" mechanical drop. 5" AW rods. VINJE & MIDDLETON ENGINEERING, INC. "S _S-. •. --~c'° - \:-.. 5' S. 5S S••. 0 5' .5.'.. 0 e S 30 20 tO 0 30 MILES FAULT —EPICENTER MAP SAN DIEGO COUNTY REGION INDICATED EARTHQUAKE EVENTS THROUGH 75 YEAR PERIOD (1900-1974) Map data is compiled from various sources including California Division of Nines and Geology, California Ins titude of. Technology and the National. Oceanic and Atmospheric Administration. Map is reproduced from California Division of Mines and Geology, "Earthquake Epicenter Map of California; Map Sheet 39." Tarthquake Magnitude ............4.0TO4.9 C ............5.0 TO 5.9 • PROJECT: Job #03-348-P .............6.0106.9 0 .......... 7.0 TO 7.9 . COVE DRIVE. CARLSBAD -------Fault. PLATE: 7 (-TA,,J, 1)60cs LOT 31, TRACT 5.162 0 -5 -10 -15 -20 E25 -30 G) 035 -40 -45 -50 -55 0 5 10 15 20 25 30 35 N160(bpf) PLATE 8 Factor of Safety LOT 3 1, TRACT 5126 Li -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -55 0.0 0.5 1.0 1.5 2.0 F.S. PLATE 9 , .i• tiivi' .'IJH( P iuiia___ iiiuIiiIInus _Illillia ___IRU IIIIIIUU IIIIII HhIIi5R I1II5U IllilliS___ ___iiinisa iiuuuis - uanisa_uuuIIusa_nuiuusa___ • ___ isa_iuuiiaua mnasuiiuisa lulls._null... isa iiunisa ounisaninisa uiiiiisa nuiiusa ___ isa lull..._uinuusa_uuiuuusa uuuuisa_ lull...____ • isa uiiivasa_uuiuusa uiuuisa lulls. iuuuuusa________ ii._iuiuiusa uuiuuuia IlliSU_IIIIIISU a.. uiunusa uuinusa nulls. uuuuusa iuinisa uuiuuisa________ ___ ____us.____ iuuuisa uuuiiusa iiiuusa uuuuiusa I isa uuuuuusa iiuuus iililllsa iiiuuusa ninusa________ • isa uuinusa niuuusa iniasa uuunisa____ I_li.. iuuuuisa uuiuuusa llIlL5R HIHU5 IIIIIIIR iunuasa________ isa unnisa uuiuuusa uinua iuuiuusa iiuuuisa___ iiuuuisa ninisa nuuui ninusa iumasa____ iiuiisa________ isa-___ IIIIIIR uiiuuusa ulnh.s iuinisa IIIIIISR ___iiuuuusa iuuuiusai.iiiniiaiiuiuusa iiinusa ___ ___isa uuiuiusa fliHl5 —lIllli5U!IlHhI ninisa___ _s. uuuiiusa ninusa nuuuuua IiJul.. liii... i.:. ' • ,fIllI•1;—• sx.1Ifiy;• _••y• If 3W1S] _PROJECT __Job ____________________________ :Cove Drive, Carlsbad -- -- DATE 09/19/03 PLATE 10 APPENDIX C PNTTNTP'P TNT( 2450 Vineyard Avenue Job #03-348-P Escondido, California 92029-1229 Phone (760) 743-1214 Fax (760) 739-0343 November 19, 2003 Mr. Jerzy J. Lewak do Nisus Software, Inc. 107 South Cedros Avenue, Suite B Solana Beach, California 92075 ADDENDUM GEOTECHNICAL REPORT, LOT 31, TRACT 5162, COVE DRIVE, CARLSBAD, CALIFORNIA In response to your request, we have completed an evaluation of an alterative ground stabilization method and foundation system which can provide adequate support for the planned duplex condominium buildings at the above-referenced project site. Alternative ground stabilization techniques and foundation support are available. However, the choice of an alterative method will depend on economic feasibility versus pros and cons of each techniqUe. The following alternative ground stabilization method and foundation support system may be considered in lieu of driven concrete piles and structural floors as previously recommended in our original report dated September 24, 2003: I. Near Surface Ground Stabilization The building envelope plus a minimum of 5 feet where possible, and as directed in the field, should be over-excavated to a minimum depth of 5 feet below the existing ground levels. Based on our subsurface exploratory excavations, the groundwater levels at the project areas are approximately 5 to 7 feet below the existing ground surfaces at the time of our field investigation. Removal depths will be predominantly above the indicated water table levels. However, construction during the dry months of the year should be considered. The building envelope includes all exterior pad footings, pop-outs, canopy supports, etc. Due to very loose to soft soils conditions in the project areas appropriate construction equipments (such as an excavator) should be considered for soil removals. 2. The soft bottom of over-excavations should be stabilized by placing minus 12-inch combined gradation rocks and tracking/consolidating with heavy construction equipment. Rock placement should continue until full rock interlocking conditions and non-yielding bottom of over-excavation is achieved as approved in the field by Mr. Jerzy J. Lewak November 19, 2003 Page 3 according to the UBC classification. Import soils should be inspected, tested as necessary, and approved by the project geotechnical engineer prior to the delivery to the site. 8. Geotechnical inspections will be required during the construction particularly when placing the initial rock mat in order to monitor ground behavior. Remedial grading operations including removals, suitability of earth deposits used as compacted fill, and compaction procedures should be continuously inspected and tested by the project geotechnical consultant and presented in the final as-graded compaction report. The nature of finished foundation bearing and subgrade soils should also be confirmed in the final compaction report at the completion of grading. Unexpected conditions may result in revised stabilization procedures including added rocks, fabrics and Geogrid as established in the field. Field conditions will control actual stabilization procedures. II. Mat I Grade Beam Foundations 1. Concrete slab-on-ground mat foundations with interior and perimeter grade beams may be considered for building support. Actual mat foundation designs should be provided by the project structural engineer based on design loading conditions and tie following soil design parameters: * A soil module of subgrade reaction of 200 pci may be considered. * A design coefficient of friction of 0.38 may be considered for concrete on foundation bearing soils. * A 2000 psf net allowable foundation pressure may be considered for certified 95% compacted foundation bearing soil. * Use a minimum 3000 psi concrete for mat foundation design. Concrete slab-on-ground mat foundations should be a minimum of 10 inches thick, reinforced with a minimum of #4 bars at 16 inches on centers maximum each way, top and bottom. Interior and perimeter grade beams should be a minimum of 18 inches wide and 24 inches deep, reinforced with at least 245 bars top and bottom and #3 ties at 24 inches on centers maximum. All depths are measured from the lowest adjacent ground level not including the sand/gravel layer under the mat. Exterior grade beams should enclose the entire building perimeter. VJNJE & MIDDLETON ENGINEERING, INC. 1 2450 Yineyard Avenue Escondido, California 92029-1229 • Phone (760) 743-1214 Mr. Jerzy J. Lewak November 19, 2003 Page 4 Foundation mats should be underlain by 4 inches of clean sand (SE 30 or greater) which is provided with a 6-mil plastic moisture barrier placed mid-height in the sand. In the case of good quality sandy subgrade soils, as approved by the project geotechnical engineer, the 6-mil plastic moisture barrier may be laid directly over the slab subgrade and covered with a minimum of 2 inches of clean sand (SE 30 or greater). 2. Foundation bearing soils should be inspected and tested as required to confirm specified conditions prior to poring the concrete. Ill. General Recommendations Recommendations provided in the referenced report, dated September 24, 2003, also remain valid and should be incorporated into the designs and implemented during the construction phase where appropriate and applicable. Uniform and stable subgrade soil conditions should also be constructed underneath the planned site driveway, parking and improvements. For this purpose, the upper loose to soft compressible soils should be removed and recompacted using the remedial grading techniques. The existing eastern fill slope may also require further stabilization. Typical depths of removals in the driveway, parking and improvement areas will be on the order of 3 to 4 feet. However, locally deeper removals may be necessary based on the actual field 'exposures and should be anticipated. Fill placement and compaction requirements will remain unchanged as specified. Final plans should reflect preliminary recommendations given in this report and reviewed and approved by the project geotechnical consultant. More specific recommendations may also be necessary and should be given when final grading and architectural/structural drawings are available. IV. Pros and Cons The driven concrete pile foundations and structural floor recommendation outlined in our original report dated September 24, 2003, were provided with the intent to prevent impacts of 'liquefaction induced settlements in a major seismic event. Alternative remedial grading and mat/grade beam foundation techniques will provide an adequate and safe building support and preclude significant structural damage or compromising the safety of its inhabitants in the event of a major seismic activity. However, liquefaction induced settlements of the deeper underlying lagoonal deposits may still VINJE & MIDDLETON ENGINEERING, INC. . 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 Mr. Jerzy J. Lewak November 19, 2003 Page 5 occur causing pad grade irregularities requiring re-leveling and repairs. Other secondary affects such as ground spreading and sand boils will not be a factor provided our remedial grading recommendations for each alterative method are implemented. The home owner(s) should evaluate the cost-benefit aspects of each alternative for choosing a construction technique. The chosen construction technique and its pros and cons should also be disclosed to the future prospective buyers and/or home owner(s). If you have any questions or need clarification, please do not hesitate to contact this office. Reference to our Job #03-348-P will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. /O 7 fltLU Dennis Middleton CEO #980 0 Ole GO CEG96O z CERTIFIED * ENGINEERING Op ,, S. Mhdi S. Shariat il( No. 48174 ReE'#48 174 Eap. 12-31.06 DM/SMSS/jt Distribution: Addressee (2) Zijistra Architecture, Attn: Mr. Sjirk Zijlstra (2) c:ijtlletters.03/03-348-P VINJE & MIDDLETON ENGINEERING., INC. • 2450 Vineyard Avenue Escondido, California 92029-1229 • Phone (760) 743-1214 4 ATTACHMENT III .; 4. ,.t II' 14 1. Period, T (sec) o 1 ci 4 Design Maps Summary Report LJSGS Design Maps Summary Report User—Specified Input Report Title 4547 Cove Drive, Carlsbad ri July 8, 20161541:39 LI IC Building Code Reference Document ASCE 710 Standard which utilizes USGS hazard data aviibIe in 2008) Site Coordinates 33.14570N, 117.3245°W Site Soil Classification Site Class E - "Soft Clay Soil" Risk Category 1/11/111 - ft. . + Oce4rnsI'\Vista cie ' Carlsba€\1 ' 5In Marcos .- , Estondido H . USGS—Provided Output S= 1.129g SMS= 1.016g SDS= 0.678g S1 = 0.434 g SM1 = 1.041 g S. = 0.694 g For information on how the SS and Si values above have been calculated from probabilistic (risk-targeted) and deterministic ground motions in the direction of maximum horizontal response, please return to the application and select the "2C09 NEHRP" building code reference document. MCEft Response Spectrum Design Response Spectrum For PGAM, TL, CRS, and CRI values, please view the detailed report. http ://ehp2-earthquake.wr.usgs .gov/designmaps/us/summarv.àhD?temnlate=minimal&latilli . 7/R/90116 Design Maps Detailed Report Page 1 of QjJ Design Maps Detailed Report ASCE 7-1.0 Standard (33.1457°N, 117.3245°W) Site Class E - "Soft Clay Soil", Risk Category 1/11/111 Section 11.4.1 - Mapped Acceleration Parameters Note: GroLrd motion values provided below are for the direction of maximum horizontal spectral response acceleration. They have been converted from corresponding geometric mean ground motions computed by the USGS by applying factors of 1.1 (to obtain S) and 1.3 (to obtain S1). Maps in the 2010 ASCE-7 Standard are provided for Site Class B. Adjustments for other Site Classes are made, as needed, in Section 11.4.3. From Figure 22-1 . Ss = 1.129 g From Figure 222 121 S1 = 0.434 g Section 11.4.2 - Site Class The authority having jurisdiction (not the USGS), site-specific geotechnical data, and/or the default has cIasified the site as Site Class E, based on the site soil properties in accordance with Chapter 20. Table 20.3-1 Site Classification Site Class Hard Rcck Rock Very dense soil and soft rock Stiff So I Soft c13y soil Soils requiring site response analysis in accordance with Section 21.1 Vs NorNth su >5,000 ft/s N/A N/A 2,500 to 5,000 ft/s N/A N/A 1,200 to 2,500 ft/s >50 >2,000 psf 600 to 1,200 ft/s 15 to 50 1,000 to 2,000 psf <600 ft/s <15 <1,000 psf Any profile with more than 10 ft of soil having the characteristics: Plasticity index P1> 20, Moisture content w ~t 40%, and Undrained shear strength S0 < 500 psf See Section 20.3,1 For Sr: lft/s = 0.3048 m/s llb/ft2 = 0.0479 kN/m2 http://ehp2-earthquake.wr.usgs. gov/de signmaps/us/report.php?template=minimal&latitude=... 7/8/2016 Design Maps Detailed Report Page 2 of 6 Section 11.4.3 - Site Coefficients and Risk-Targeted Maximum Considered Earthquake (MCER) Spectral Response Acceleration Parameters Table 11.4-1: Site Coefficient F Site Class Mapped MCE R Spectral Response Acceleration Parameter at Short Period S 5 0.25 S5 = 0.50 S5 = 0.75 S5 = 1.00 Ss 2! 1.25 A 0.8 0.8 0.8 0.8 0.8 B 1.0 1.0 1.0 1.0 1.0 C 1.2 1.2 1.1 1.0 1.0 D 1.6 1.4 1.2 1.1 1.0 E 2.5 1.7 1.2 0.9 0.9 F See Section 11.4.7 of ASCE 7 Note: Use straight-line interpolation for intermediate values of Ss For Site Class = E and S = 1.129 g, F. = 0.900 Table 11,4-2: Site Coefficient F. Site Class Mapped MCE R Spectral Response Acceleration Parameter at 1-s Period S1 :5 0.10 S1 = 020 S1 = 0.30 S1 = 0.40 S1 > 0.50 A 0.8 0.8 0.8 . 0.8 0.8 B 1.0 1.0 1.0 1.0 1.0 C 1.7 1.6 1.5 1.4 1.3 D 2.4 2.0 1.8 1.6 1.5 E 3.5 3.2 2.8 [ 2.4 2.4 F See Section 11.4.7 of ASCE 7 Note: Use straight-line interpolation for intermediate values of S For Site Class = E and S1 = 0.434 g, F. = 2.400 http :f/ehp2-earthquake .wr.usgs.gov/designmaps/us/report.php?temp1ateminima1&1atitude=.. 7/R/70 1 tc Design Maps Detailed Report Page 3 of 6 45 Equation (11.4-1): SMS = FaSs = 0.900 x 1.129 = 1.016 g Equation (11.4-2): S11 = FS1 = 2.400 x 0.434 = 1.041 g Section 1..4.4 - Design Spectral Acceleration Parameters Equation (11.4-3): S05%SM5%xl.016=0.678g Equation (11.4-4): S01 = % Sf41 = 2/3 x 1.041 = 0.694 g Section 11.4.5 - Design Response Spectrum From Figure 22-12. 13) TL = 8 seconds Figure 11.4-1: Design Response Spectrum 0 I Period, T (sec) http ://ehp2-earthquake.wr.usgs .gov/designmaps/us/report.php?template—mjnjmaJ&1atjtue=.. 7/8/20.16 5.. 1O16 s..=1,001 C V 'V V r0203 T=i015 P.dod, T (st) Design Maps Detailed Report Page 4 of 6 Section 11.4.6 - Risk-Targeted Maximum Considered Earthquake (MCER) Response Spectrum The MCER Response Spectrum is determined by multiplying the design response spectrum above by 1.5. http://ehp2-earthquake.wr.usgs 7/8/2016 I Design Maps Detailed Report Page 5 of 6 Section 11.8.3- Additional Geotechnical Investigation Report Requirements for Seismic Design Categories D through F From Figure 22-7 J41 PGA = 0,446 Equation (11.8-1) PGAM = FPGAPGA = 0.900 x 0.446 = 0.401 g Table 11.8-1: Site Coefficient FA Site Mapped MCE Geometric Mean Peak Ground Acceleration, PGA Class PGA PGA = PGA = PGA = PGA > 0.10 0.20 0.30 0.40 0.50 A 0.8 0.8 0.8 0.8 0.8 B 1.0 1.0 1.0 1.0 1.0 C 1.2 1.2 1.1 1.0 1.0 D 1.6 1.4 1.2 1.1 1.0 E 2.5 1.7 1.2 0.9 0.9 F See Section 11.4.7 of ASCE 7 Note: Use straight-line interpolation for intermediate values of PGA For Site Class = E and PGA = 0.446 g, F = 0.900 Section 21.2.1.1 - Method 1 (from Chapter 21 - Site-Specific Ground Motion Procedures for Seismic Design) From Figure 153 0.947 From Figure 22-18 Er" CR1 = 0.999 http ://ehp2-earthquake.wr.usgs .gov/designmaps/us/reort.php?template=m injmal&1 atitude=... 7/R/2016 Design Maps Detailed Report Page 6 of 6 Section 11.6 - Seismic Design Category Table 11.6-1 Seismic Design Category Based on Short Period Response Acceleration Parameter VALUE OF SOS - RISK CATEGORY lorll III IV SDS A A A 0.1679S05 <0.33g B B C 0.33g S < 0.50g C C D 0.509S0 D D D For Risk Category = I and SDs = 0.678 g, Seismic Design Category = D Table 11.6-2 Seismic Design Category Based on 1-S Period Response Acceleration Parameter VALUE.OF SDI RISK CATEGORY lorli III IV S01 < 0.0679 A A A 0.067g < 0.1339 B B C 0.133g SDI <0.20g C C D 0.20gS0 D D D For Risk Category = I and S, = 0.694 g, Seismic Design Category = D Note: When S is greater than or equal to 0.75g, the Seismic Design Category is E for buildings in Risk Categories I, II, and 111, and F for those in Risk Category IV, irrespective of the above. Seismic Design Category "the more severe design category in accordance with Table 11.6-1 or 11.6-2" = D Note: See Section 11.6 for alternative approaches to calculating Seismic Design Category. References Figure 22-1: http ://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7figure_22-1.pdf Figure 22-2: http ://ea rthquake.usgs.gov/ hazards/designmaps/downloads/pdfs/2010_ASCE-7_Figure_22-2. pdf Figure 22-12: http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7_Figure_22- 12.pdf Figure 22-7: http ://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7_Figure_22-7. pdf Figure 22-17: http ://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7.jigure_22- 17.pdf Figure 22-18: http ://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7_Figurej2- 18.pdf http://ehp2earthquake.wr.usgs.gov/designmaDs/us/reoort.nhn?temn1ate=minin1 lRr1tithd= 7/Q/')01 ,<