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Home My WebLink AboutSDP 16-12; CARLSBAD VETERANS HOUSING; REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION; 2016-04-04w CHRISTIAN WHEELER- EN G IN E I R ING RECOR) COPY *&_ /16 Date OF PRELIMINARY GEOTECHNICAL INVESTIGATION AFFIRMED HARDING STREET 3606.3618 AND 3630 HARDING STREET CARLSBAD, CALIFORNIA __1uJ 061 AFFIRMED HOUSING GROUP 13520 EVENING CREEK DRIVE N, SUITE 160 SAN DIEGO, CALIFORNIA 92128 PREPARED BY: CHRISTIAN WHEELER ENGINEERING 3980 HOME AVENUE SAN DIEGO, CALIFORNIA 92105 3980 Home Avenue + San Diego, CA 92105 + 619-550-1700 + FAX 619-550-1701 w CHRISTIAN WHEELEft ENGINEERING August 4, 2016 Affirmed Housing Group 13520 Evening Creek Drive N, Suite 160 San Diego, California 92128 Attention: Sydney Cordova CWE 2160237.02R Subject: Report of Preliminary Geotechnical Investigation Affirmed Harding Street, 3606-3618 and 3630 Harding Street, Carlsbad, California Ladies and Gentlemen: In accordance with your request and our proposal dated April 20, 2016, we have completed a geotechnical investigation for the subject project. We are presenting herewith a report of our findings and recommendations. It is our professional opinion and judgment that no geotechnical conditions exist on the subject property that would preclude the construction of the proposed apartment project provided the recommendations presented herein are followed. If you have questions after reviewing this report, please do not hesitate to contact our office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, CHRISTIAN WHEELER ENGINEERING NAL CERTIFIED —4 II I ENGINEERING I GEOLOGIST / Expires 7-3117 eDaniiel.!&037 DBA:tsw Sydney@afffrmecthousing.com Troy S. Wilson, C.E.G. #2551 3980 Home Avenue + San Diego, CA 92105 + 619-550-1700 + FAX 619-550-1701 TABLE OF CONTENTS Page Introduction and Project Description.....................................................................................................1 Scopeof Services.....................................................................................................................................2 Findings..................................................................................................................................................3 SiteDescription...................................................................................................................................3 General Geology and Subsurface Conditions......................................................................................3 Topsoil/Artificial Fill......................................................................................................................3 OldParalic Deposits ....................................................................................................................4 SantiagoFormation......................................................................................................................4 Groundwater.................................................................................................................................... 4 TectonicSetting...............................................................................................................................5 General, Geologic Hazards .................................................................................................................5 General............................................................................................................................................5 SurfaceRupture...............................................................................................................................5 SlopeStability..................................................................................................................................5 Liquefaction.....................................................................................................................................6 Flooding..........................................................................................................................................6 Tsunamis.........................................................................................................................................6 Seiches.............................................................................................................................................6 Potential Storm Water Infiltration Hazards ....................................................................................6 General............................................................................................................................................6 Conclusions..........................................................................................................................................10 Recommendations................................................................................................................................11 Gradingand Earthwork....................................................................................................................11 General..........................................................................................................................................11 PregradeMeeting ........................................................................................................................... Observationof Grading.................................................................................................................11 Clearingand Grubbing..................................................................................................................11 SitePreparation .............................................................................................................................11 Processingof Fill Areas .................................................................................................................12 Compactionand Method of Filling................................................................................................12 SurfaceDrainage............................................................................................................................12 Foundations......................................................................................................................................13 General..........................................................................................................................................13 Dimension..................................................................................................................................13 BearingCapacity.........................................................................................................................13 FootingReinforcing ..................................................................................................................... 13 Lateral Load Resistance...............................................................................................................14 Property Line Foundation Excavations ...................... ................................................................... 14 Foundation Excavation Observation...............................................................................................14 SettlementCharacteristics .............................................................................................................14 ExpansiveCharacteristics................................................................................................................14 FoundationPlan Review ................................................................................................................14 SolubleSulfates .................................................................. . ............................................................ 15 SeismicDesign Factors ..................................................................................................................15 On-Grade Slabs.................................................................................................................................16 CWE 2160237.02R Affirmed Harding Street 3606-3618 and 3630 Harding Street Carlsbad, California L General . 16 Interior Floor Slabs . 16 Under-Slab Vapor Retarders..........................................................................................................16 Exterior Concrete Flatwork..........................................................................................................16 EarthRetaining Walls ....................................................................................................................... 17 Foundations.................................................................................................................................... 17 PassivePressure .............................................................................................................................17 ActivePressure .............................................................................................................................. 17 Waterproofing and Wall Drainage Systems ....................................................................................17 Backfill........................................................................................................................................... 18 StormWater BMPs ...........................................................................................................................18 General...........................................................................................................................................18 ImpermeableLiners.......................................................................................................................18 Infiltration Basin Construction .....................................................................................................18 RoutineMaintenance.....................................................................................................................18 Limitations............................................................................................................................................19 Review, Observation and Testing.....................................................................................................19 Uniformityof Conditions.................................................................................................................19 Changein Scope................................................................................................................................19 TimeLimitations ..............................................................................................................................20 ProfessionalStandard........................................................................................................................20 Client's Responsibility......................................................................................................................20 FieldExplorations ................................................................................................................................21 LaboratoryTesting...............................................................................................................................21 ATTACHMENTS TABLES Table I Seismic Design Parameters, 2013 CBC FIGURES Figure 1 Site Vicinity Map, Follows Page 1 PLATES Plate 1 Site Plan & Geotechnical Map Plates 2 Retaining Wall Subdrain APPENDICES Appendix A Subsurface Explorations Appendix B Laboratory Test Results Appendix C References Appendix D Recommended Grading Specifications-General Provisions Appendix E Worksheet C.4-1 Feasibility CWE 2160237.02R Affirmed Harding Street 3606-3618 and 3630 Harding Street Carlsbad, California I w CHRISTIAN WHEELER ENGINEERING PRELIMINARY GEOTECHNICAL INVESTIGATION AFFIRMED HARDING STREET 3606-3618 AND 3630 HARDING STREET CARLSBAD, CALIFORNIA INTRODUCTION AND PROJECT DESCRIPTION This report presents' the results of a preliminary geotechnical investigation performed fcr proposed apartment project to be constructed at 3060-3618 and 3630 Harding Street, Carlsbad, California. The following Figure No. 1 presents a vicinity map showing the location of the property. We understand that it is proposed to demolish the existing improvements and construct a three-story apartment building. The lower level of the structure will consist primarily of parking. The building will be of wood-frame construction, will be supported by shallow foundations, and will incorporate a conventional concrete slab-on-grade floor system. Grading to establish proposed grades is expected to consist of cuts and fills up to about 2 feet in depth. To assist in the preparation of this report, we were provided with miscellaneous plans prepared by Dahlin Group, dated January 19, 2016, and an undated topographic map of unknown origin. A copy of the topographic map was used as a base map for our Site Plan and Geologic Map, and is included herein as Plate No. 1. This report has been prepared for the exclusive use of Affirmed Housing Group, and its design consultants, for specific application to the project described herein. Should the project be modified, the conclusions and recommendations presented in this report should be reviewed by Christian Wheeler Engineering for conformance with our recommendations and to determine whether any additional subsurface investigation, laboratory testing and/or recommendations are necessary. Our professional services have been performed, our findings obtained and our recommendations prepared in accordance 3980 Home Avenue + San Diego, CA 92105 + 619-550-1700 + FAX 619-550-1701 SITE VICINITY OnStreetMap contributors , PROJECT SITE , * '49 _ MAvje t 000 I I 'I HARDING STREET AFIRMED HOUSING 360., 3618 AND 363C IARDING STREET CARLSBAD, CALIFORNIA LATE: AUGUST 2016 JOB NO.: 2160237.02R SRD FIGURE NO.: 1 4 054 OF CHRISTIAN WHEELER ENGINE E RING CWE 2160237.02R August 4, 2016 Page No. 2 with generally accepted engineering principles and practices. This warranty is in lieu of all other warranties, expressed or implied. SCOPE OF SERVICES Our preliminary geotechnical investigation consisted of surface reconnaissance, subsurface exploration, obtaining representative soil samples, laboratory testing, analysis of the field and laboratory data, and review of relevant geologic literature. Our scope of service did not include assessment of hazardous substance contamination, recommendations to prevent floor slab moisture intrusion or the formation of mold within the structures, evaluation or design of storm water infiltration facilities, or any other services not specifically described in the scope of services presented below. More specifically, the intent of our proposed investigation was to: Drill three small-diameter borings to explore the subsurface conditions of the site and to obtain samples for laboratory testing. Backfill the boring holes using a grout or a grout/bentonite mix as required by the County of San Diego Department of Environmental Health. Evaluate, by laboratory tests and our past experience with similar soil types, the engineering properties of the various soil strata that may influence the proposed construction, including bearing capacities, expansive characteristics and settlement potential. Describe the general geology at the site including possible geologic hazards and liquefaction potential that could have an effect on the proposed construction, and provide the seismic design parameters as required by the 2013 edition of the California Building Code. Address potential construction difficulties that may be encountered due to soil conditions, groundwater or geologic hazards, and provide geotechnical recommendations to deal with these difficulties. Provide a preliminary report based on the findings of our field explorations. The report will include preliminary foundation design recommendations as well as a preliminary site infiltration potential evaluation. Provide site preparation and grading recommendations for the anticipated work. Provide foundation recommendations for the proposed structure and develop soil engineering design criteria for the recommended foundation designs. CWE 2160237.02R August 4, 2016 Page No. 3 Provide a preliminary geotechnical report that presents the results of our investigation which includes a plot plan showing the location of our subsurface explorations, excavation logs, laboratory test results, and our conclusions and recommendations for the proposed project. Although a test for the presence of soluble sulfates within the soils that may be in contact with reinforced concrete was performed as part of the scope of our services, it should be understood Christian Wheeler Engineering does not practice corrosion engineering. If a corrosivity analysis is considered necessary, we recommend that the client retain an engineering firm that specializes in this field to consult with them on this matter. The results of our sulfate testing should only be used as a guideLne to determine if additional testing and analysis is necessary. FINDINGS SITE DESCRIPTION The subject site is located at 3606-3618 and 3630 Harding Street, Carlsbad, California. The near rectanular-shaped lot presently supports three residential structures and a detached garage. Topographically, the site is near flat-lying. The property is bounded on the west by Harding Street, on the east by Highway 5, on the north by an apartment structure, and on the south by a single-family residence. GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located within the Coastal Plains Physiographic Province of San Diego County. Based on the results of our subsurface explorations, and analysis of readily available, pertinent geologic literature, it was determined that the site is generally underlain by topsoil/artificial fill, old paralic deposits, and Santiago Formation deposits (see Plate Nos. 2 through 4). These materials are described below: TOPSOIL/ARTIFICIAL FILL (Top/Qaf): The site is underlain by a relatively thin layer of undifferentiated topsoil/artificial fill. As encountered in our borings, these materials extend to a maximum depth of about 4 feet below existing grade (boring B-3). Deeper topsoil/artificial fill CWE 2160237.02R August 4, 2016 Page No. 4 may exist in areas of the site not investigated. These materials generally consisted of brown and dark brown, dry to moist, loose, silty sand (SM). The topsoil/artificial fill was judged to have a very low expansion potential (El <20). The soil was judged to be in Hydrologic Soil Group B and considered susceptible to hydro-collapse. OLD PARALIC DEPOSITS (Qop): Quaternary-age old paralic (terrace) deposits were encountered underlying the undifferentiated topsoil/artificial fill. The old paralic deposits extended to a depth of about 11 feet below existing grade. The old paralic deposits generally consisted of light brown, light orangish-brown, and light gray, moist to very moist, medium dense and dense, poorly graded sand with silt (SP-SM), with some interbedded layers of silty sand (SM). The upper 1112 feet was weathered within boring B-i. The old paralic deposits were judged to have a very low Expansion Index (El <20). The soil was judged to be in Hydrologic Soil Group C and considered susceptible to hydro-collapse. SANTIAGO FORMATION (Tsa): Tertiary-age sedimentary deposits of the Santiago Formation were encountered underlying the old paralic deposits at a depth of about 11 feet below existing grade. The formational soils generally consisted of light gray and olive gray, very moist and moist, silty sand (SM) and clayey sand (SC). The sandy Santiago Formation was judged to have a very low Expansion Index (El <20) whereas the clayey formational soils were judged to have a low to medium Expansion Index (El between 21 and 90). Based on the soil conditions observed and the perched water, the soil was judged to be in Hydrologic Soil Group D. GROUNDWATER: Perched groundwater was encountered in all the borings at the contact between the old paralic deposits and the Santiago Formation. In general, groundwater was encountered at a depth of about 11 feet below existing grade. We do not expect any significant groundwater related conditions during or after the proposed construction. However, it should be recognized that minor groundwater seepage problems might occur after construction and landscaping are completed, even at a site where none were present before construction. These are usually minor phenomena and are often the result of an alteration in drainage patterns and/or an increase in irrigation water. Based on the anticipated construction and the permeability of the on-site soils, it is our opinion that any seepage problems that may occur will be minor in extent. It is further our opinion that these problems can be most effectively corrected on an individual basis if and when they occur. CWE 2:60237.02R August 4, 2016 Page No. 5 TECTONIC SETTING: It should be noted that much of Southern California, including the San Diego County area, is characterized by a series of Quaternary-age fault zones that consist of several individual, en echelon faults that generally strike in a northerly to northwesterly direction. Some of these fault zones (and the individual faults within the zone) are classified as active while others are classified as only potentially active according to the criteria of the California Division of Mines and Geology. Active fault zones are those which have shown conclusive evidence of faulting during the Holocene Epoch (the most recent 11,000 years) while potentially active fault zones have demonstrated movement during the Pleistocene Epoch (11,000 to 1.6 million years before the present) but no movement during Holocene time. Inactive faults are those faults that can be demonstrated to have no movement in the past 1.6 million years. It should be recognized that the active Rose Canyon Fault Zone is located approximately 41/2 miles southwest of the site. Other active fault zones in the region that could possibly affect the site include the Coronado Bank, San Diego Trough, and San Clemente Fault Zones to the west, the Palos Verdes and Newport-Inglewood Fault zones to the northwest, and the Elsinore, Earthquake Valley, San Jacinto and San Andreas Fault Zones to the northeast. GENERAL GEOLOGIC HAZARDS GENERAL: The site is located in an area where the risks due to significant geologic hazards are relatively low. No geologic hazards of sufficient magnitude to preclude the construction of the subject project are known to exist. In our professional opinion and to the best of our knowledge, the site is suitable for the proposed improvements. SURFACE RUPTURE: There are no known active faults that traverse the subject site; therefore, the risk for surface rupture at the subject site is considered low. SLOPE STABILITY: As part of this investigation we reviewed the publication, "Landslide Hazards in the Northern Part of the San Diego Metropolitan Area" by Tan and Giffen, 1995. This reference is a comprehensive study that classifies San Diego County into areas of relative landslide susceptibility. The western portion of the subject site is located in Area 2, which is considered to be "marginally suscep:ible" to slope failures. The eastern portion of the subject site is located in Area 3-1, which is CWE 2160237.02R August 4, 2016 Page No. 6 considered to be "generally susceptible" to slope failures. Based on our findings and the proposed construction, it is our opinion that the likelihood of slope stability related problems with the site is low. An offsite slope, associated with the Interstate 5, is located adjacent to the eastern edge of the site. Based on the topography map provided, this slope ranges from 13 to 16 feet high and has an inclination that ranges from 1.5:1 to 2:1 (horizontal to vertical). This slope was not investigated as part of our geotechnical investigation. Based on the idea that this slope was properly engineered, constrdcted and graded by Caltrans, we do not anticipate any slope stability related issues for the slope. It is our understanding that the slope will be replaced with a retaining wall as part of a future highway expansion. The schedule of the future construction is unknown. LIQUEFACTION: The earth materials underlying the site are not considered subject to liquefaction due to such factors as soil density, grain-size distribution, the absence of shallow groundwater condit:ons. FLOODING: As delineated on the Flood Insurance Rate Map (FIRM) prepared by the Federal Emergency Management Agency, the site is not located within either the 100-year flood zone or the 500-year flood zone. TSUNAMIS: Tsunamis are great sea waves produced by submarine earthquakes or volcanic eruptions. Due tc the site's setback from the ocean and elevation, it will not be affected by a tsunami. SEICHES: Seiches are periodic oscillations in large bodies of water such as lakes, harbors, bays or reservoirs. Due to the site's location, it will not be affected by seiches. POTENTIAL STORM WATER INFILTRATION HAZARDS: GENERAL: Based on the current Storm Water Standards, BMP Design Manual, certain geotechnical criteria need to be addressed when assessing the feasibility and desirability of the use of infiltration BMPs for a project site. The manual states that if during the planning stage, one or more of these CWE 2160237.02R August 4, 2016 Page No. 7 factors precludes infiltration as an approach, it is not necessary to assess every other factor. However, if proposing infiltration BMPs, then every applicable factor in this section must be addressed. C2.1: SOIL AND GEOLOGIC CONDITIONS: Site soil and geologic conditions influence the rate at which water can physically enter the soils. Site assessment approaches for soil and geologic conditions may consists of a) review of soil survey maps; b) Review of available reports on local geology to identify relevant features, such as depth to bedrock, rock type, lithology, faults, and hydrostratigraphic or confining units; c) Review of previous geotechnical investigations of the area; and d) Site specific geotechnical and/or geologic investigations (e.g. borings, infiltration tests). We have performed a site specific geotechnical investigation for the project. No published infiltration/percolation rates were discovered within the vicinity of the site. C2.2 SETTLEMENT AND VOLUME CHANGE: Settlement and volume change can occur when water is introduced below grade. Settlement refers to a condition when soils decrease in volume (i.e. hydro collapse, calcareous soils, consolidation or liquefaction). Heave refers to expansion of soils or an increase in volume (i.e. expansive soils or frost heave). Based upon the subgrade soil conditions observed in our borings and the anticipated grading for the proposed improvements, the site is underlain by sandy soil that would be prone to hydro-collapse when saturated. Therefore, the risk of settlement due to infiltration of stormwater would be considered to oe high. . Lining the sides and base of the biofiltration basins would reduce the risk of hydro- collapse.. C2.3 SLOPE STABILITY: Infiltration of water has the potential to increase the risk of failure to nearby slopes. The site is relatively level, and no descending slopes are located within a reasonable proximity of the site. However, an ascending slope is located at the eastern edge of the site. Saturation of the soil at the toe of this slope could cause reduction in passive pressure. This risk can be mitigated by using an impermeable liner that extends at least 5 feet below grade to prevent lateral migration, or completely lining the BMP. In addition, BMP basins that incorporate uncompacted soils should not be located within 5 feet of the toe of the existing eastern slope. C2.4 UTILITY CONSIDERATIONS: Utilities are either public or private infrastructure components that include underground pipelines, vaults, and wires/conduit, and above ground CWE 2160237.02R August 4, 2016 Page No. 8 wiring and associated structures. Infiltration of water can pose a risk to subsurface utilities, or geotechnical hazards can occur within the utility trenches when water is introduced. The planned use of the site will be for a multi-family residential structure. Underground utilities are anticipated as part of the construction. The risk of introducing water into a utility trench would be considered moderate to high depending on the proximity of the stormwater BMP to utilities. This risk can be mitigated by using an impermeable liner that extends below the depth of the lowest utility, or completely lining the BMP. C2.5 GROUNDWATER MOUNDING: Groundwater mounding occurs when infiltrated water creates a rise in the groundwater table beneath the facility. Groundwater mounding can affect nearby subterranean structures and utilities. Based on the soil conditions and perched groundwater encountered below the site, the risk of groundwater mounding below the basin would be moderate if infiltration was allowed. C2.6 RETAINING WALL AND FOUNDATIONS: Infiltration of water can result in potential increases in lateral pressures and potential reduction in soil strength. Retaining walls and foundations can be negatively impacted by these changes in soil conditions. We understand that retaining walls will not be constructed as part of the proposed project. The footprint of the proposed structure is expected to take up a large portion of the property. The risk of a potential reduction in soil strength below foundations would be expected to be high. This risk can be mitigated by using an impermeable liner that extends at least 3 feet below the depth of the lowest foundation, or completely lining the BMP. C2.7 OTHER FACTORS: No other factors were considered. C3.1 SOIL AND GROUNDWATER CONTAMINATION: Infiltration should be avoided in areas where infiltration could contribute to the movement or dispersion of soil or groundwater contamination or adversely affect ongoing clean-up efforts, either on site or down-gradient of the project. We have no knowledge of any soil or groundwater contamination on or adjacent the subject site. CWE 2160237.02R August 4, 2016 Page No. 9 C3.2 SEPARATION TO SEASONAL HIGH GROUNDWATER: The depth to seasonal high groundwater beneath the base of the infiltration BMP must be greater than 10 feet for infiltration to be allowed. The depth of the groundwater requirement can be reduced from 10 feet at the discretion of the approval agency if the groundwater basin does not support beneficial uses and the groundwater quality is maintained at the proposed depth. The estimated high seasonal groundwater level is expected to be approximately 10 feet below existing grade. We have no knowledge as to whether the groundwater basin supports beneficial uses. C3.3 WELLHEAD PROTECTION: Wellheads, natural and man-made, are water resources that may potentially be adversely impacted by storm water infiltration through the introduction of contaminants or alterations in water supply and levels. Infiltration BMPs must be located a minimum of 100 feet horizontally from any water supply well. We have no knowledge of any water supply wells within 100 feet of the site. C3.4 CONTAMINATION RISKS FROM LAND USE ACTIVITIES: Concentration of storm water pollutants in runoff is highly dependent on the land uses and activities present in the area tributary to an infiltration BMP. Infiltration BMPs must not be used for areas of industrial or light industrial activity. We have no knowledge of any sites classified as industrial or light industrial within the area tributary to the site, nor will the site's proposed use be classified as industrial or light industrial. C3.5 CONSULTATION WITH APPLICABLE GROUNDWATER AGENCIES: As presented in the current Storm Water Standards BMP Design Manual, infiltration activities should be coordinated with the applicable groundwater management agency to ensure groundwater quality is protected. It is recommended that coordination be initiated as early as possible during the planning process. C3.6 WATER BALANCE IMPACTS ON STREAM FLOW: As presented in the current Storm Water Standards BMP Design Manual, use of infiltration systems to reduce surface water discharge volumes may result in additional volume of deeper infiltration compared to natural conditions, which may result in impacts to receiving channels associated with change in dry weather flow regimes. We have not evaluated this impact as part of our study. CWE 2160237.02R August 4, 2016 Page No. 10 C3.7 DOWNSTREAM WATER RIGHTS: As presented in the current Storm Water Standards BMP Design Manual, there may be cases in which infiltration of water from an area that was previously allowed to drain freely to downstream water bodies would not be legal from a water rights perspective. We have not evaluated this impact as part of our study. CONCLUSIONS In general, it is our professional opinion and judgment that the subject property is suitable for the construction of the proposed apartment structure provided the recommendations presented herein are implemented. The main geotechnical condition encountered affecting the proposed project consists of potentially compressible topsoil/artificial fill and old paralic deposits. These conditions are discussed hereinafter. The sit2 is underlain by relatively thin layer of potentially compressible undifferentiated topsoil/artificial fill and weathered old paralic deposits extending to depths ranging from about 31/2 feet to 5 feet from existing grade. Deeper topsoil/artificial fill and weathered paralic deposits may exist in areas of the site not investigated. These deposits are considered unsuitable, in their present condition, for the support of settlement sensitive improvements. Therefore, it is recommended that potentially compressible topsoil/artificial fill and paralic deposits be removed and replaced as compacted fill. In addition, some of the old paralic deposits are potentially collapsible upon saturation. Additional foundation and concrete slab thickness and reinforcement are recommended to mitigate this condition. It is our opinion that storm water systems incorporating infiltration are not appropriate for the site due to the potential for hydro-consolidation of the site soils. A completed and signed "Worksheet CA-1: Categorization of Infiltration Feasibility Condition" for the subject project is included in Appendix F of this report. The site is located in an area that is relatively free of geologic hazards that will have a significant effect on the proposed construction. The most likely geologic hazard that could affect the site is ground shaking due to seismic activity along one of the regional active faults. However, construction in accordance with the requirements of the most recent edition of the California Building Code and the CWE 2160237.02R August 4, 2016 Page No. 11 local governmental agencies should provide a level of life-safety suitable for the type of development proposed. RECOMMENDATIONS GRADING AND EARTHWORK GENERAL: All grading should conform to the guidelines presented in the current edition of the California Building Code, the minimum requirements of the City of Carlsbad, and the recommended Grading Specifications and Special Provisions attached hereto, except where specifically superseded in the text of this report. PREGRADE MEETING: It is recommended that a pregrade meeting including the grading contractor, the client, and a representative from Christian Wheeler Engineering be performed, to discuss the recommendations of this report and address any issues that may affect grading operations. OBSERVATION OF GRADING: Continuous observation by the Geotechnical Consultant is essential during the grading operation to confirm conditions anticipated by our investigation, to allow adjustments in design criteria to reflect actual field conditions exposed, and to determine that the grading proceeds in general accordance with the recommendations contained herein. CLEARING AND GRUBBING: Site preparation should begin with the demolition of existing improvements. The resulting debris and any existing vegetation and other deleterious materials in areas to receive proposed improvements or new fill soils should be removed from the site. SITE PREPARATION: It is recommended that existing potentially compressible artificial fill/topsoil and weathered old paralic deposits underlying proposed structures, associated improvements, and new fills should be removed in their entirety. Based on our findings, the maximum anticipated removal depth is 5 feet below e*isting grade. Deeper removals may be necessary in areas of the site not investigated or due to unforeseen conditions. Lateral removals limits should extend at least 5 feet from the perimeter of the structures, any settlement sensitive improvements, and new fills or equal to removal depth, whichever is more. No removals are recommended beyond property lines. All CWE 2160237.02R August 4, 2016 Page No. 12 excavated areas should be approved by the geotechnical engineer or his representative prior to replacing any of the excavated soils. The excavated materials can be replaced as properly compacted fill in accordance with the recommendations presented in the "Compaction and Method of Filling" section of this report. PROCESSING OF FILL AREAS: Prior to placing any new fill soils or constructing any new improvements in areas that have been cleaned out to receive fill, the exposed soils should be scarified to a depth of 12 inches, watered thoroughly, and compacted to at least 90 percent relative compaction. COMPACTION AND METHOD OF FILLING: In general, all structural fill placed at the site should be compacted to a relative compaction of at least 90 percent of its maximum laboratory dry density as determined by ASTM Laboratory Test D1557. Fills should be placed at or slightly above optimum moisture content, in lifts six to eight inches thick, with each lift compacted by mechanical means. Fills should consist of approved earth material, free of trash or debris, roots, vegetation, or other materials determined to be unsuitable by the Geotechnical Consultant. Fill material should be free of rocks or lumps of soil in excess of three inches in maximum dimension. Utility trench backfill within five feet of the proposed structure and beneath all concrete flatwork or pavements should be compacted to a minimum of 90 percent of its maximum dry density. SURFACE DRAINAGE: The drainage around the proposed improvements should be designed to collect and direct surface water away from proposed improvements toward appropriate drainage facilities. Rain gutters with downspouts that discharge runoff away from the structures into controlled drainage devices are recommended. The ground around the proposed improvements should be graded so that surface water flows rapidly away from the improvements without ponding. In general, we suggest that the ground adjacent to structures be sloped away at a minimum gradient of 2 percent. For densely vegetated areas where runoff can be impaired should have a minimum gradient of 5 percent for the first 5 feet from the structure is suggested. It is essential that new and existing drainage patterns be coordinated to produce proper drainage. Pervious hardscape surfaces adjacent to structures should be similarly graded. CWE 2160237.02R August 4, 2016 Page No. 13 Drainage patterns provided at the time of construction should be maintained throughout the life of the proposed improvements. Site irrigation should be limited to the minimum necessary to sustain landscape growth. Over watering should be avoided. Should excessive irrigation, impaired drainage, or unusually high rainfall occur, zones of wet or saturated soil may develop. FOUNDATIONS GENERAL: Based on our findings and engineering judgment, the proposed structure and associated improvements may be supported by conventional shallow continuous and isolated spread footings. The following recommendations are considered the minimum based on the anticipated soil conditions after site preparation as recommended in our forthcoming geotechnical report is perforraed, and are not intended to be lieu of structural considerations. All foundations should be designed by a qualified professional. DIMENSIONS: Spread footings supporting the proposed structure should be embedded at least 24 inches below lowest adjacent finish pad grade. Continuous and isolated footings should have a minimum width of 12 inches and 24 inches, respectively. Continuous and isolated footings supporting exterior light improvements should have a minimum embedment of 12 inches, and have a minimum width of 12 inches and 18 inches, respectively. BEARING CAPACITY: Spread footings supporting the proposed structure and exterior improvements may be designed for an allowable soil bearing pressure of 2,000 pounds per square foot (pst). This value may be increased by 600 pounds per square foot for each additional foot of embedment and 300 pounds per square foot for each additional foot of width up to a maximum of 4,000 pounds per square foot. Property line footings may be design for an allowable soil bearing pressure of 1,000 psf. These values may be increased by one-third for combinations of temporary loads such as those due to wind or seismic loads. FOOTING REINFORCING: Reinforcement requirements for foundations should be provided by a structural designer. However, based on the expected soil conditions, we recommend that the minimum reinforcing for continuous footings consist of at least 2 No. 5 bars positioned near the bottom of the footing and 2 No. 5 bars positioned near the top of the footing. CWE 2160237.02R August 4, 2016 Page No. 14 LATERAL LOAD RESISTANCE: Lateral loads against foundations may be resisted by friction between the bottom of the footing and the supporting soil, and by the passive pressure against the footing. The coefficient of friction between concrete and soil may be considered to be 0.30. The passive resistance may be considered to be equal to an equivalent fluid weight of 300 pounds per cubic foot. These values are based on the assumption that the footings are poured tight against undisturbed soil. If a combination of the passive pressure and friction is used, the friction value should be reduced by one- third. PROPERTY LINE FOUNDATION EXCAVATIONS:: It is recommended that the bottom of property line foundation excavations be moisture conditioned and compacted to at least 95 percent relative compaction. FOUNDATION EXCAVATION OBSERVATION: All footing excavations should be observed by Christian Wheeler Engineering prior to placing of forms and reinforcing steel to determine whether the foundation recommendations presented herein are followed and that the foundation soils are as anticipated in the preparation of this report. All footing excavations should be excavated neat, level, and square. All loose or unsuitable material should be removed prior to the placement of concrete. SETTLEMENT CHARACTERISTICS: The anticipated total and differential settlement is expected to be less than about 1 inch and 1 inch over 40 feet, respectively, provided the recommendations presented in this report are followed. It should be recognized that minor cracks normally occur in concrete slabs and foundations due to concrete shrinkage during curing or redistribution of stresses, therefore some cracks should be anticipated. Such cracks are not necessarily an indication of excessive vertical movements. EXPANSIVE CHARACTERISTICS: The prevailing foundation soils are assumed to have a very low expansive potential (El <20). The recommendations within this report reflect these conditions. FOUNDATION PLAN REVIEW: The final foundation plan and accompanying details and notes should be submitted to this office for review. The intent of our review will be to verify that the plans used for construction reflect the minimum dimensioning and reinforcing criteria presented in this section and that no additional criteria are required due to changes in the foundation type or layout. It is not our CWE 2160237.02R August 4, 2016 Page No. 15 intent to review structural plans, notes, details, or calculations to verify that the design engineer has correctly applied the geotechnical design values. It is the responsibility of the design engineer to properly design/specify the foundations and other structural elements based on the requirements of the structure and considering the information presented in this report. SOLUBLE SULFATES: The water soluble sulfate content of a selected soil sample from the site was determined in accordance with California Test Method 417. The results of this test indicate that the soil sample had a soluble sulfate content of 0.005 percent. Soils with a soluble sulfate content of less than 0.1 percent are considered to be negligible. Therefore, no special requirements are considered necessary for the concrete mix design. SEISMIC DESIGN FACTORS The seismic design factors applicable to the subject site are provided below. The seismic design factors were cetermined in accordance with the 2013 California Building Code. The site coefficients and adjusted maximum considered earthquake spectral response acceleration parameters are presented in the following Table I. TABLE I: SEISMIC DESIGN FACTORS Site Coordinates: Latitude Longitude 33.1560 -117.3390 Site Class D Site Coefficient Fa 1.043 Site Coefficient F 1.562 Spectral Response Acceleration at Short Periods S5 1.143 g Spectral Response Acceleration at 1 Second Period Si 0.438 g SMSFaSs 1.192 g SMi=FvSi 0.685 g SDs=2/3SMs 0794 g SDI=2/3*SMi 0.456 g Probable ground shaking levels at the site could range from slight to moderate, depending on such factors as the magnitude of the seismic event and the distance to the epicenter. It is likely that the site will experience the effects of at least one moderate to large earthquake during the life of the proposed improvements. CWE 260237.02R August 4, 2016 Page No. 16 ON-GRADE SLABS GENERAL: It is our understanding that the floor system of the proposed structure will consist of a concrete slab-on-grade. The following recommendations are considered the minimum slab requirements based on the soil conditions and are not intended in lieu of structural considerations. These recommendations assume that the site preparation recommendations contained in this report are implemented. INTERIOR FLOOR SLABS: The minimum slab thickness should be 5 inches (actual) and the slab should be reinforced with at least No. 4 bars spaced at 18 inches on center each way. Slab reinforcement should be supported on chairs such that the reinforcing bars are positioned at mid- height in the floor slab. The slab reinforcement should extend down into the perimeter footings at least 6 inches. UNDER-SLAB VAPOR RETARDERS: Steps should be taken to minimize the transmission of moisture vapor from the subsoil through the interior slabs where it can potentially damage the interior floor coverings. Local industry standards typically include the placement of a vapor retarder, such as plastic, in a layer of coarse sand placed directly beneath the concrete slab. Two inches of sand are typically used above and below the plastic. The vapor retarder should be at least 15-mil Stegowrap® or similar material with sealed seams and should extend at least 12 inches down the sides of the interior and perimeter footings. The sand should have a sand equivalent of at least 30, and contain less than 10% passing the Number 100 sieve and less than 5% passing the Number 200 sieve. The membrane should be placed in accordance with the recommendation and consideration of ACT 302, "Guide for Concrete Floor and Slab Construction" and ASTM E1643, "Standards Practice for Installation of Water Vapor Retarder Used in Contact with Earth or Granular Fill Under Concrete Slabs." It is the flooring contractor's responsibility to place floor coverings in accordance with the flooring manufacturer specifications. EXTERIOR CONCRETE FLATWORK: Exterior concrete slabs on grade should have a minimum thickness of 4 inches and be reinforced with at least No. 3 bars placed at 18 inches on center each way (ocew). Driveway slabs should have a minimum thickness of 5 inches and be reinforced with at least No. 4 bars placed at 12 inches ocew. Driveway slabs should be provided with a thickened edge a least CWE 2160237.02R August 4, 2016 Page No. 17 12 inches deep and 6 inches wide. All slabs should be provided with weakened plane joints in accordance with the American Concrete Institute (ACT) guidelines. Special attention should be paid to the method of concrete curing to reduce the potential for excessive shrinkage cracking. It should be recognized that minor cracks occur normally in concrete slabs due to shrinkage. Some shrinkage cracks should be expected and are not necessarily an indication of excessive movement or structural distress. EARTH RETAINING WALLS FOUNDATIONS: Foundations for any proposed retaining walls should be constructed in accordance with the foundation recommendations presented previously in this report. PASSIVE PRESSURE: The passive pressure for the anticipated foundation soils may be considered to be 300 pounds per square foot per foot of depth. The upper foot of embedment should be neglected when calculating passive pressures, unless the foundation abuts a hard surface such as a concrete slab. The passive pressure may be increased by one-third for seismic loading. The coefficient of friction for concrete to soil may be assumed to be 0.30 for the resistance to lateral movement. When combining frictional and passive resistance, the friction should be reduced by one-third. ACTIVE PRESSURE: The active soil pressure for the design of "unrestrained" and "restrained" earth retaining structures with level backfill may be assumed to be equivalent to the pressure of a fluid weighing 37 and 57 pounds per cubic foot, respectively. These pressures do not consider any other surcharge. If any are anticipated, this office should be contacted for the necessary increase in soil pressure. These values are based on a drained backfill condition. Seismic lateral earth pressures may be assumed to equal an inverted triangle starting at the bottom of the wall with the maximum pressure equal to 10H pounds per square foot (where H = wall height in feet) occurring at the top of the wall. WATERPROOFING AND WALL DRAINAGE SYSTEMS: The need for waterproofing should be evaluated by others. If required, the project architect should provide (or coordinate) waterproofing details for the retaining walls. The design values presented above are based on a drained backfill CWE 2160237.02R August 4, 2016 Page No. 18 condition and do not consider hydrostatic pressures. Unless hydrostatic pressures are incorporated into the design, the retaining wall designer should provide a detail for a wall drainage system. Typical retaining wall drain system details are presented as Plate No. 2 of this report for informational purposes. Additionally, outlets points for the retaining wall drain system should be coordinated with the project civil engineer. BACKFILL: Retaining wall backfill soils should be compacted to at least 90 percent relative compaction. Expansive or clayey soils should not be used for backfill material. The wall should not be backfilied until the masonry has reached an adequate strength. STORM WATER BMPs: GENERAL: It is our opinion that storm water systems incorporating infiltration are not appropriate for the site due to the potential for hydro-consolidation of the site soils. IMPERMEABLE LINERS: We recommend that storm water BMPs be completely lined with an impermeable membrane to prevent infiltration. The membrane should extend a minimum of 6 inches above the overflow height. Care should be taken in design as not to create a slide plane on the face of the slope. Membrane seams and pipe penetrations should be properly sealed per manufacturer or designer specification. INFILTRATION BASIN CONSTRUCTION: If biofiltration basins are constructed as the project's BMPs. the toe of the proposed basin slope should be set back a minimum of 2 feet from the loose soil media as to provide a competent base for the slope. In addition, a berm should be constructed at the top of slope around the perimeter of the basin in order to minimize surficial erosion of the slope. ROUTINE MAINTENANCE: If biofiltration basins are constructed as the project's BMPs, it should be recognized that routine inspection and maintenance of the BMPs are necessary to prevent clogging and failure. At times the BMPs will require excavation of the clogged media. Consideration should be given to providing appropriate access ramps for equipment to bring and remove materials during maintenance. CWE 2160237.02R August 4, 2016 Page No. 19 LIMITATIONS REVIEW, OBSERVATION AND TESTING The recommendations presented in this report are contingent upon our review of final plans and specifications. Such plans and specifications should be made available to the geotechnical engineer and engineering geologist so that they may review and verify their compliance with this report and with the California Building Code. It is recommended that Christian Wheeler Engineering be retained to provide continuous soil engineering services during the earthwork operations. This is to verify compliance with the design concepts, specifications or recommendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior to start of construction. UNIFORMITY OF CONDITIONS The recommendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluation of the subsurface soil conditions encountered at the subsurface exploration locations and on the assumption that the soil conditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations and/or cut and fill slopes may be influenced by undisclosed or unforeseen variations in the soil conditions that may occur in the intermediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site development should be brought to the attention of the geotechnical engineer so that he may make modifications if necessary. CHANGE IN SCOPE This office should be advised of any changes in the project scope or proposed site grading so that we may determine if the recommendations contained herein are appropriate. This should be verified in writing or modified by a written addendum. CWE 2160237.02R August 4, 2016 Page No. 20 TIME LIMITATIONS The findings of this report are valid as of this date. Changes in the condition of a property can, however, occur with the passage of time, whether they be due to natural processes or the work of man on this or adjacent properties. In addition, changes in the Standards-of-Practice and/or Government Codes may occur. Due to such changes, the findings of this report may be invalidated wholly or in part by changes beyond our control. Therefore, this report should not be relied upon after a period of two years without a review by us verifying the suitability of the conclusions and recommendations. PROFESSIONAL STANDARD In the performance of our professional services, we comply with that level of care and skill ordinarily exercised by members of our profession currently practicing under similar conditions and in the same locality. The client recognizes that subsurface conditions may vary from those encountered at the locations where our borings, surveys, and explorations are made, and that our data, interpretations, and recommendations be based solely on the information obtained by us. We will be responsible for those data, interpretations, and recommendations, but shall not be responsible for the interpretations by others of the information developed. Our services consist of professional consultation and observation only, and no warranty of any kind whatsoever, express or implied, is made or intended in connection with the work performed or to be performed by us, or by our proposal for consulting or other services, or by our furnishing of oral or written reports or findings. CLIENT'S RESPONSIBILITY It is the responsibility of the Client, or its representatives, to ensure that the information and recommendations contained herein are brought to the attention of the structural engineer and architect for the project and incorporated into the project's plans and specifications. It is further their responsibility to take the necessary measures to insure that the contractor and his subcontractors carry out such recommendations during construction. CWE 2160237.02R August 4, 2016 Page No. 21 FIELD EXPLORATIONS Three ;ubsurface explorations were made on April 13, 2016 at the locations indicated on the Site Plan and Geotechnical Map included herewith as Plate No. 1. These explorations consisted of borings drilled utilizirg a truck mounted drill rig (Mobile B61). The fieldwork was conducted under the observation and direction of our engineering geology personnel. The explorations were carefully logged when made. The trench logs are presented on Appendix A. The soils are described in accordance with the Unified Soils Classification. In addition, a verbal textural description, the wet color, the apparent moisture, and the density or consistency is provided. The density of granular soils is given as very loose, loose, medium dense, dense or very dense. The consistency of silts or clays is given as either very soft, soft, medium stiff, stiff, very stiff, or hard. Relatively undisturbed chunk and bulk samples of the earth materials encountered were collected. Samples were transported to our laboratory for testing. LABORATORY TESTING Laboratory tests were performed in accordance with the generally accepted American Society for Testing and Materials (ASTM) test methods or suggested procedures. A brief description of the tests performed and the subsequent results are presented in Appendix B. \ V \A \\ \\ \ \ Ad A \\\\\\\\\\ \ \\\\\( \%\ \ .22P \ \\\\\\\\\\\\\\ \ \\\\\\\\\\\ ( fliTsa7 Tsa \ Vk\ \\\ \'\\ \\ \ " -1 \ \ \\\\\K V•- \ X8.7 XtiB l3.2 0 40 80 K6 0 B-2 SCALE: 1" = 40 \ tIll .1 21 XIII XII.5 CWE LEGEND 3 APPROXIMATE GEOTECHNICAL BORING LOCATION 162.3 APPROXIMATE GEOLOGIC CONTACT L ARTIFICIAL FILL OVER 202 OLD PARAUC DEPOSITS OVER SANTIAGO FORMATION OLD PARAUC DEPOSITS OVER Ts. SANTIAGO FORMATION 21 APPROXIMATE PROPERTY LINE LOCATON HARDING STREET AFFIRMED HOUSING - 3606-3618 AND 3630 HARDING STREET SITE PLAN GEOTECHNICAL AND MAP CARLSBAD. CALIFORNIA DATE: AUGUST 2016 JOB NO.: 2160237.0216 CI- Ilk TI,\NwFIEIThEIY BY: SD PLATE NO.: 1 ENGINEER INC 1:1 LIII DETAIL DETAIL 6"MIN. 6'MIN. : EI±TO511I _ DETAIL DETAIL NOTES AND DETAILS GENERAL NOTES: 1) THE NEED FOR WATERPROOFING SHOULD BE EVALUATED BY OTHERS. 2) WATERPROOFING TO BE DESIGNED BY OTHERS (CWE CAN PROVIDE A DESIGN IF REQUESTED). 3) EXTEND DRAIN TO SUITABLE DISCHARGE POINT PER CIVIL ENGINEER. 4) DO NOT CONNECT SURFACE DRAINS TO SUBDRAIN SYSTEM. DETAILS: O 4-INCH PERFORATED PVC PIPE ON TOP OF FOOTING, HOLES UNDERLAY SUBDRAIN WITH AND CUT FABRIC BACK FRC POSITIONED DOWNWARD (SDR 35, SCHEDULE 40, OR EQUIVALENT). 0 DRAINAGE PANELS AND WRAP FABRIC AROUND PIPE. INCH OPEN-GRADED CRUSHED AGGREGATE. COLLECTION DRAIN (TOTAL DRAIN OR EQUIVALENT) () GEOFARBRIC WRAPPED COMPLETELY AROUND ROCK. LOCATED AT BASE OF WALL DRAINAGE PANEL PER MANUFACTURER'S RECOMMENDATIONS. PROPERLY COMPACTED BACKFILL SOIL. O WALL DRAINAGE PANELS (MIRADRAIN OR EQUIVALENT) PLACED PER MANUFACTURERS REC'S. HARDING STREET AFFIRMED HOUSING 3606-3618 AND 3630 HARDING STREET CANTILEVER RETAINING WALL ___________ CARLSBAD, CALIFORNIA DRAINAGE SYSTEMS DATE: AUGUST 2016 JOB NO.: 2160237.02R BY: SRD PLATE NO.: 2 CHRISTIAN WHEELER ENGINEERING Appendix A Subsurface Explorations LOG OF TEST BORING B-i Sample Type and Laboratory Test Legend SPT Standard 'n na et DR Drive Ring ST Shelby Tube Date Logged: 4/13/16 Equipment: Mobil B-61 MD Max Density DS Direct Shear Logged By: DJF Auger Type: 6 inch Hollow Stem SO4 Soluble Sulfates Co. Consolidation SA Sieve Analysis El Expansion Index Existing Elevation: 62.5 feet Drive Type: 1401bs/30 inches HA Hydrometer R-Vol Resistance Value SE Sand Equivalent Chi Soluble Chlorides Proposed Elevation: N/A Depth to 'Water: N/A Pt Plasticity Index Rex pl-I & Resistivity CP Collapse Potential SD Sample Density 0 0 -. 1-n z 0 z C SUMMARY OF SUBSURFACE CONDITIONS W4 . (based on Unified Soil Classification System) 0 SM Topsoil: Brown, dry, loose, very fine- to medium-grained, SILTY SAND; porous -------- SM Old Paralic Deposits (Qop): Light orangish-brown, damp, medium dense, very 30 Cal 1.7 112.3 fine to nedis grainedSILTY SAND; slihtliwdat1ierbd to 31h féet -- - -- --------- ------+- ------- +-- -----, 50/5W Cal 8.0 112.6 CP 5-- ----.- -- ------..-Moderatelycementeo-w-ith.reddish-iron-staining--------- --.-- --- --.--- -------- -•. - ---- -.- -- .-.--- -- Moi;ethumdense. --- - 21 SPT SA SP. Light orangish-brown, moist, medium dense, very fine- to medium-grained, 11 SPT .' -SM -----v---- ------------.- --' ------ - SP— Light brown, moist to very moist medium dense fine-to coarsegrained__ —a- - -v - POORLY GRADED SAND. 24 Cal 8.1 99.2 , Very moist seepage/perched water at 11 feet 62 SPT SM Santiago Formation (Tsa): Light gray, moist, very dense, very fine- to ----m-----------'- ---------------- + - --.---,-----a------------- 50/2" Cal -+-------±- 14.3 -- --1-----,- 1145 --1-5-- - - --------.-- ---+- ----------.. ------- - ---- -.- - - 50/Y SPT - --- withroots. --------------------- --- ------------ ---------- --.---.- ---- -- • - - - -- ITI. _'a -- - --+- -,- --- - 50/1' 50/3' SPT - - -- Cal, -i------ -- - -f------+-- --, -- -- * - -.- ---a- -- -i--- -------- —f------v----.----a---------t-----.---a- - ---- - ------------±---,•----4-- --20- . MINT -----,-_ -. -•------ 50/6' 'SPT -- - - Boring terminated at 20 feet. Seepage encountered at ii feet. --------* -------i---- ----------------'- I —i------_-- --'------- -'-----'-- - ----,-. --- --- + -'-- - —25--L --- - t - ----- - * 7- -30 — -------* ii -- ------•- -------- -------- - ---- - +--------- - - Symbol Legend HARDING STREET AFFIRMED HOUSING Groundwater Level During Drilling 3606-3618 AND 3630 HARDING STREET 9 V Groundwater Level After Drilling CARLSBAD, CALIFORNIA - - Apparent Seepage DATE: AUGIJS'I 2016 JOB NO.: 2160237.02R CHRISTIAN WHEELER ENGINEIRING BY: SRD APPENDIX A: -A-i ** Non-Representative Blow Count (rocks present) LOG OF TEST BORING B-2 Sample Type and Laboratory Test Legend SPT Standard 'n t DR Drive Ring ST Shelby Tube Date Logged: 4/13/16 Equipment: Mobil B-61 MD Max Density US Direct Shear Logged By: DJF Auger Type: 6 inch Hollow Stem SO4 Soluble Sulfates Con Consolidation SA Sieve Analysis El Expansion Index Existing Elevation: 62.0 feet Drive Type: 1401bs/30 inches 1' Hydrometer R-Va1 Resistance Value SE Sand Equivalent Chi Soluble Chlorides Proposed Elevation: N/A Depth to 'l'ater: N/A Pt Plorticity Index Res pH & Resistivity Cl' Collapse Potential SD Sample Density Co Z1 ui a- Z o 04 - SUMMARY OF SUBSURFACE CONDITIONS (based on Unified Soil Classification System) - p. 0 SM Topsoil /Artificial Undifferentiated: Dark brown, moist, loose, very fine- to - SA - .. - - - medium-grained,-SILTY SAND;-porous,with abundant fooiA . ----MD ChI 8 Cal DS - - SP Old Paralic Deposits (Qop) Light -brown moist itedium dense very-fine 5 - SM - medium graine POORLY GRADED SAND with silt and orgish mottling. 1 - 7.7 - 112 9 CP ... Slightly weathered to 5 feet. Medium dense to dense. fll . 37 Cal 8.4 115.1 -10 --. Very moist, perched water/seepage at 10½ feet. *.------ -- SM Santiago Formation (Tsa): Light gray, most, very dense, very fine- to -..- - ------.---- . mixclium-gr1ined'-SILTY SAND. -.-- .-- - .- x. I -- ----.- --.-.--- 72 - -- Cal . 13.3 115.6 Boring terminated at 15 feet. Seepage encountered at 10½ feet. . ---- ii 1:TJE ij ± --- I: ._ _. ..: . --- - - -f-- ---- - - --- - -------*- - -f F --F . 1 I f—— -f-- +--+h--------*-- I - - - --39-- ----:--- ---4---•- ----'-----------'--,----------* ' -----c ---- ______ -• -- -- - _ -Notes:---- - - -- -----,----*- --- ------i - ---- --------- - -- -- ---- ---------- - -'- - . - - Symbol Legend HARDING STREET AFFIRMED HOUSING Groundwater Level During Drilling 3606-3618 AND 3630 HARDING STREET V Groundwater Level After Drilling CARLSBAD, CALIFORNIA - ( Apparent Seepage * DATE: AUGUST 2016 CHRISTIAN WHEELER.NoSampleRecoe JOB NO.: 2160237.02R FNCNFERINC. BY: SRD APPENDIX A: A-2 ** Non-Representative Blow Count frocks present) LOG OF TEST BORING B-3 Sample Type and Laboratory Test Legend SPT Standard P,.etmuo. Test DR Drive Ring ST Shelby Tube Date Logged: 4/13/16 Equipment: Mobil B-61 MD Mw Density DS Direct Shear Logged By: DJF Auger Type: 6 inch Hollow Stem ype: 504 Soluble Sulfates Con Consolidation SA Sieve Analysis El Expansion Index Existing Elevation: 62.3 feet Drive Type: 1401bs/30 inches HA Hydrometer R-Val Value SE Sand Equivalent Chl S Resistance oluble Chlorides Proposed Elevation: N/A Depth to Water: N/A P1 Plasticity Index Res pI-I & Resistivity CP Collapse Potential SD Sample Density SUMMARY OF SUBSURFACE CONDITIONS (based on Unified Soil Classification System) 0 4'ofPCC. - - ---- -SM -Topsoil/-Aificial-Undifferentiated:*Dark browndp, loose,very-fine- to - -- medium-grained, SILTY SAND with roots. 5 Cal SP Old Paralic Deposits (Qop) Light brown moist medium dense very fine- to 19 Cal 3.7 106.1 - SM idi-grainPOOPLYtRADEDSAND3Thsili - .Slight1yweatheredio.5Jeet... Light gray, moist medium dense very fine to medium grained POORLY SP GRAD --- ------ -,----- ------ -.-- -- ---- ,- ---. - 20 Cal 5.3 100.8 Very moist perched water/saeepag at 11 feet. SM Santiago Formation (Tsa): Light gray, very moist, very dense, very fine- to - - - - medium-grained,-SIL-TY-SAND. F Moist se— - Light gray to olive-gray, moist very dense very fine to medium grained, -- -_ . - - - -_ --- -- —1-5-- H- -'-- - CLAYEY SAND. 62 - Cal - - - - - Boring terminated at 15 feet. Seepage encountered at 11 feet. - ___- -- ----- - ----- ---- .- - -. ------ ,--- ---- --.--------- - - -- -- - -- ---------- - ------- +-7 ---- ----- - - t__• ----- ---_---------- --.-- --- -1 v--- -- -.- -- -- ---- - --- - -- - - -•- - .- -4- _-----------i--------------------±---+---f-------,----_--------------------- --- - -------- --------':---- --- -- ------ --, -- ---- -25- -----a------ -30 Symbol Legend HARDING STREET AFFIRMED HOUSING Groundwater Level During Drilling - 3606-3618 AND 3630 I-lARDING STREET - V Groundwater Level After Drilling CARLSBAD, CALIFORNIA ( Apparent Seepage DATE: AUGUST 2016 JOB NO.: 2160237.02R CHRISTIAN \VH[[LER. NoSampleRecovery ENGINEERING BY: SRD APP-ENDIX A: A-3 ** Non-Representative Blow Count (rocks present) Appendix B Laboratory Test Results Laboratory tests were performed in accordance with the generally accepted American Society for Testing and Materials (ASTM) test methods or suggested procedures. Brief descriptions of the tests performed are presented below: CLASSIFICATION: Field classifications were verified in the laboratory by visual examination. The final soil classifications are in accordance with the Unified Soil Classification System and are presented on the exploration logs in Appendix A. MOISTURE-DENSITY: MOISTURE-DENSITY: In-place moisture contents and dry densities were determined for selected soil samples in accordance with ATM D 1188. The results are summarized in the boring logs presented in Appendix A. MAXIMUM DRY DENSITY AND OPTIUM MOISTURE CONTENT TEST: The maximum dry density and optimum moisture content of a selected soil sample were determined in the laboratory in accordance with ASTM D 1557, Method A. DIRECT SHEAR: Direct shear tests were performed on selected samples of the on-site soils in accordance with ASTM D 3080. GRAIN SIZE DISTRIBUTION: The grain size distribution of a selected sample was determined in accordance with ASTM C136 and/or ASTM D 422. COLLAPSE POTENTIAL: Collapse potential test were performed on selected undisturbed soil samples in accordance with ASTM D 5333. SOLUBLE SULFATES: The soluble sulfate content of a selected soil sample was determined in accordance with California Test Method 417. N LAB SUMMARY CI-IRI S11AN WHEELER E N G I N E E R I N C BY: DBA I DATE: JUNE2016 I REPORTNO:2160237.02R I FIGURENO.: B-I LABORATORY TEST RESULTS AFFIRMED HARDING STREET 3606-3618 AND 3630 HARDING STREET CARLSBAD, CALIFORNIA MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT (ASTM D1557) Sample Location Boring 2 @ 0-31/2' Sample Description Brown Silt Sand (SM) Maximum Density 128.1 pcf Optimum Moisture 8.6% DIRECT SHEAR (ASTM D3080) Sample Location Boring 2 @ 0-31/2' Sample Type Remolded to 90 % Friction Angle 33° Cohesion 100 psf GRAIN SIZE DISTRIBUTION (ASTM D422) Sample Location Boring I @ 61/2' Boring 2 @ 0-31/2' Sieve Size Percent Passing Percent Passing #4 90 99 #8 86 100 #16 100 99 #30 93 91 #50 65 58 #100 44 32 #200 38 24 COLLAPSE POTENTIAL (ASTM D 5333) Sample Location Boring I @ 5' Boring 2 @ 5' Initial Moisture Content 8.0% 7.7% Initial Density 112.6 pcf 112.9 pcf Consolidation Before Water Added 8.2% 4.6% Consolidation After Water Added 10.1% 4.8% Final Moisture 14.5% 13.0% SOLUBLE SULFATES (CALIFORNIA TEST 417) Sample Location Boring 2 @ 0.31/2' Soluble Sulfate 0.005 % (SO4) CWE 2160237.02R August 4, 2016 Plate No. B-2 Appendix C References CWE 2160237.02R August 4, 2016 Appendix C-i REFERENCES Bryant, W. A. (compiler), 2005, Digital Database of Quaternary and Younger Faults from the Fault Activity Map of California, version 2.0: California Geological Survey Web Page, http://www.consrv.ca.gov/CGS/information/publications/QuaternaryFaultsver2.htm Historic Aerials, NETR Online, historicaerials.com Jennings, C.W. and Bryant, W. A., 2010, Fault Activity Map, California Geological Survey, Geologic Data Map No. 6, http://www.quake.ca.gov/gmaps/FAM/faultactivitymap.html Kennecy, Michael P. and Tan, Siang S., 2007, Geologic Map of the Oceanside 30'x60' Quadrangle, California, California Geologic Survey, Map No. 2. Tan, S.S., 1995, Landslide Hazards in the Northern Part of the San Diego Metropolitan Area, San Diego County, California, California Division of Mines and Geology Open-File Report 95-04. U.S. Geological Survey, U.S. Seismic Design Maps Web Application, http://geohazards.usgs.gov/designmaps/us/application.php U.S. Geological Survey, Quaternary Faults in Google Earth, http://earthquake.usgs.gov/hazards/qfaults/google.php Appendix D Recommended Grading Specifications - General Provisions CWE 2160237.02R August 4, 2016 Appendix D, Page D-1 RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS AFFIRMED HARDING STREET 3606-3618 AND 3630 HARDING STREET CARLSBAD, CALIFORNIA GENERAL INTENT The intent of these specifications is to establish procedures for clearing, compacting natural ground, preparing areas to be filled, and placing and compacting fill soils to the lines and grades shown on the accepted plans. The recommendations contained in the preliminary geotechnical investigation report and/or the attached Special Provisions are a part of the Recommended Grading Specifications and shall supersede the provisions contained hereinafter in the case of conflict. These specifications shall only be used in conjunction with the geotechnical report for which they are a part. No deviation from these specifications will be allowed, except where specified in the geotechnical report or in other written communication signed by the Geotechnical Engineer. OBSERVATION AND TESTING Christian Wheeler Engineering shall be retained as the Geotechnical Engineer to observe and test the earthwork in accordance with these specifications. It will be necessary that the Geotechnical Engineer or his representative provide adequate observation so that he may provide his opinion as to whether or not the work was accomplished as specified. It shall be the responsibility of the contractor to assist the Geotechnical Engineer and to keep him appraised of work schedules, changes and new information and data so that he may provide these opinions. In the event that any unusual conditions not covered by the special provisions or preliminary geotechnical report are encountered during the grading operations, the Geotechnical Engineer shall be contacted for further recommendations. If, in the opinion of the Geotechnical Engineer, substandard conditions are encountered, such as questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse weather, etc., construction should be stopped until the conditions are remedied or corrected or he shall recommend rejection of this work. CWE 2160237.02R August 4, 2016 Appendix D, Page D-2 Tests used to determine the degree of compaction should be performed in accordance with the following American Society for Testing and Materials test methods: Maximum Density & Optimum Moisture Content - ASTM D-1557-91 Density of Soil In-Place - ASTM D-1556-90 or ASTM D-2922 All densities shall be expressed in terms of Relative Compaction as determined by the foregoing ASTM testing procedures. - PREPARATION OF AREAS TO RECEIVE FILL All vegetation, brush and debris derived from clearing operations shall be removed, and legally disposed of. All areas disturbed by site grading should be left in a neat and finished app arance, free from unsightly debris. After clearing or benching the natural ground, the areas to be filled shall be scarified to a depth of 6 inches, brought to the proper moisture content, compacted and tested for the specified minimum degree of compaction. All loose soils in excess of 6 inches thick should be removed to firm natural ground which is defined as natural soil which possesses an in-situ density of at least 90 percent of its maximum dry density. When the slope of the natural ground receiving fill exceeds 20 percent (5 horizontal units to 1 vertical unit), the original ground shall be stepped or benched. Benches shall be cut to a firm competent formational soil. The lower bench shall be at least 10 feet wide or 1-1/2 times the equipment width, whichever is greater, and shall be sloped back into the hillside at a gradient of not less than two (2) percent. All other benches should be at least 6 feet wide. The horizontal portion of each bench shall be compacted prior to receiving fill as specified herein for compacted natural ground. Ground slopes flatter than 20 percent shall be benched when considered necessary by the Geotechnical Engineer. Any abandoned buried structures encountered during grading operations must be totally removed. All underground utilities to be abandoned beneath any proposed structure should be removed from within 10 feet of the structure and properly capped off. The resulting depressions from the above CWE 2160237.02R August 4, 2016 Appendix D, Page D-3 described procedure should be backfilled with acceptable soil that is compacted to the requirements of the Geotechnical Engineer. This includes, but is not limited to, septic tanks, fuel tanks, sewer lines or leach lines, storm drains and water lines. Any buried structures or utilities not to be abandoned should be brought to the attention of the Geotechnical Engineer so that he may determine if any special recommendation will be necessary. All water wells which will be abandoned should be backfilled and capped in accordance to the requirements set forth by the Geotechnical Engineer. The top of the cap should be at least 4 feet below finish grade or 3 feet below the bottom of footing whichever is greater. The type of cap will depend on the diameter of the well and should be determined by the Geotechnical Engineer and/or a qualified Structural Engineer. FILL MATERIAL Materials to be placed in the fill shall be approved by the Geotechnical Engineer and shall be free of vegetable matter and other deleterious substances. Granular soil shall contain sufficient fine material to fill the voids. The definition and disposition of oversized rocks and expansive or detrimental soils are covered in the geotechnical report or Special Provisions. Expansive soils, soils of poor gradation, or soils with low strength characteristics may be thoroughly mixed with other soils to provide satisfactory fill material, but only with the explicit consent of the Geotechnical Engineer. Any import material shall be approved by the Geotechnical Engineer before being brought to the site. PLACING AND COMPACTION OF FILL Approved fill material shall be placed in areas prepared to receive fill in layers not to exceed 6 inches in compacted thickness. Each layer shall have a uniform moisture content in the range that will allow the compaction effort to be efficiently applied to achieve the specified degree of compaction. Each layer shall be uniformly compacted to the specified minimum degree of compaction with equipment of adequate size to economically compact the layer. Compaction equipment should either be specifically designed for soil compaction or of proven reliability. The minimum degree of compaction to be achieved is specified in either the Special Provisions or the recommendations contained in the preliminary geotechnical investigation report. CWE 2160237.02R August 4, 2016 Appendix D, Page D-4 When the structural fill material includes rocks, no rocks will be allowed to nest and all voids must be carefully filled with soil such that the minimum degree of compaction recommended in the Special Provisions is achieved. The maximum size and spacing of rock permitted in structural fills and in non- structural fills is discussed in the geotechnical report, when applicable. Field observation and compaction tests to estimate the degree of compaction of the fill will be taken by the Geotechnical Engineer or his representative. The location and frequency of the tests shall be at the Geotechnical Engineer's discretion. When the compaction test indicates that a particular layer is at less than the required degree of compaction, the layer shall be reworked to the satisfaction of the Geotechnical Engineer and until the desired relative compaction has been obtained. Fill slojes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction by sheepsfoot roller shall be at vertical intervals of not greater than four feet. In addition, fill slopes at a ratio of two horizontal to one vertical or flatter, should be trackrolled. Steeper fill slopes shall be over-built and cut-back to finish contours after the slope has been constructed. Slope compaction operations shall result in all fill material six or more inches inward from the finished face of the slope having a relative compaction of at least 90 percent,of maximum dry density or the degree of compaction specified in the Special Provisions section of this specification. The ccmpaction operation on the slopes shall be continued until the Geotechnical Engineer is of the opinion that the slopes will be surficially stable. Density tests in the slopes will be made by the Geotechnical Engineer during construction of the slopes to determine if the required compaction is being achieved. Where failing tests occur or other field problems arise, the Contractor will be notified that day of such conditions by written communication from the Geotechnical Engineer or his representative in the form of a daily field report. If the method of achieving the required slope compaction selected by the Contractor fails to produce the necessary results, the Contractor shall rework or rebuild such slopes until the required degree of compaction is obtained, at no cost to the Owner or Geotechnical Engineer. CWE 2160237.02R August 4, 2016 Appendix D, Page D-5 CUT SLOPES The Engineering Geologist shall inspect cut slopes excavated in rock or lithified formational material during the grading operations at intervals determined at his discretion. If any conditions not anticipated in the preliminary report such as perched water, seepage, lenticular or confined strata of a potentially adverse nature, unfavorably inclined bedding, joints or fault planes are encountered during grading, these conditions shall be analyzed by the Engineering Geologist and Geotechnical Engineer to determine if mitigating measures are necessary. Unless otherwise specified in the geotechnical report, no cut slopes shall be excavated higher or steeper than that allowed by the ordinances of the controlling governmental agency. ENGINEERING OBSERVATION Field observation by the Geotechnical Engineer or his representative shall be made during the filling and compaction operations so that he can express his opinion regarding the conformance of the grading with acceptable standards of practice. Neither the presence of the Geotechnical Engineer or his representative or the observation and testing shall release the Grading Contractor from his duty to compact all fill material to the specified degree of compaction. SEASON LIMITS Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy rain, filling operations shall not be resumed until the proper moisture content and density of the fill materials can be achieved. Damaged site conditions resulting from weather or acts of God shall be repaired before acceptance of work. RECOMMENDED GRADING SPECIFICATIONS - SPECIAL PROVISIONS RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted natural ground, compacted fill, and compacted backfill shall be at least 90 percent. For street and CWE 2160237.02R August 4, 2016 Appendix D, Page D-6 parking lot subgrade, the upper six inches should be compacted to at least 95 percent relative compaction. EXPANSIVE SOILS: Detrimentally expansive soil is defined as clayey soil which has an expansion index cf 50 or greater when tested in accordance with the Uniform Building Code Standard 29-2. OVERSIZED MATERIAL: Oversized fill material is generally defined herein as rocks or lumps of soil over 6 inches in diameter. Oversized materials should not be placed in fill unless recommendations of placement of such material are provided by the Geotechnical Engineer. At least 40 percent of the fill soils shall pass through a No. 4 U.S. Standard Sieve. TRANSITION LOTS: Where transitions between cut and fill occur within the proposed building pad, the cut portion should be undercut a minimum of one foot below the base of the proposed footings and recompacted as structural backfill. In certain cases that would be addressed in the geotechnical report, special footing reinforcement or a combination of special footing reinforcement and undercutting may be required. Appendix E Worksheet C.4-1: Categorization of Infiltration Feasibility Condition Appendix C: Geotechnical and Groundwater Investigation Worksheet C.4-1: Categorization of Infiltration Feasibility Condition Part 1 - Full Infiltration Feasibility Screening Criteria Would infiltration of the full design volume be feasible from a physical perspective without any ündesirakle consequences that cannot be reasonably mitigated? Criteria Screening Question Yes No Is the estimated reliable infiltration rate below proposed facility locations 1 greater than 0.5 inches per hour? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. I Provide basis: The infiltration rate of the on-site soils has not been measured. Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of geotechnical hazards (slope stability, groundwater 2 mounding, utilities, or other factors) that cannot be mitigated to an x acceptable level? The response to this Screening Question shall be based on a comnrehensive Pvliiition of the factor nresentecl in Annendix Ci. I Provide basis: C.2.2 Settlement and Volume Change: The on- and off-site fills and paralic deposits are subject to consolidation and/or hydro-collapse as a result of increased moisture content that will result in settlement on adjacent improvements. It is our professional opinion that this hazard cannot be reasonably mitigated to an acceptable level. Storm Water Standards Part 1: BMP Design Manual C-12 Appendix C: Geotechnical and Groundwater Investigation Criteria Screening Question Yes No Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of groundwater contamination (shallow water table, storm 3 water pollutants or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comnrehensive evaluation of the factors nresented in Annendix C.3. Provide basis: The risk of groundwater contamination has not been evaluated at this time. Can infiltration greater than 0.5 inches per hour be allowed without causing potential water balance issues such as change of seasonality of ephemeral streams or increased discharge of contaminated groundwater to surface waters? The response to this Screening Question shall be based on p comprehensive evaluation of the factors nresented in Annendix C.3. Provide basis: The risk of causing potential water balance issues such as change of seasonality of ephemeral streams or increased discharge of contaminated groundwater to surface waters has not been evaluated at this time. If all answers to rows 1 - 4 are "Yes" a full infiltration design is potentially feasible. The feasibility screening category is Full Infiltration Part 1 Result* If any answer from row 14 is "No", infiltration may be possible to some extent but would not generally be feasible or desirable to achieve a "full infiltration" design. Proceed to Part 2 10 be completed using gathered site information and best professional judgment considering the definition of MEP in the MS-4 Permit. Additional testing and/or studies may be required by City Engineer to substantiate findings. Storm Water Standards Part 1: BMP Design Manual C-12 Appendix C: Geotechnical and Groundwater Investigation Part 2 - Partial Infiltration vs. No Infiltration Feasibility Screening Criteria Would infiltration of water in any appreciable amount be physically feasible without any negative consequences that cannot be reasonably mitigated? Criteria Screening Question Yes No Do soil and geologic conditions allow for infiltration in any appreciable rate or volume? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. Provide basis: The infiltration rate of the on-site soils has not been measured. Can Infiltration in any appreciable quantity be allowed without increasing risk of geotechnical hazards (slope stability, groundwater 6 mounding, utilities, or other factors) that cannot be mitigated to an x acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. Provide basis: C.2.2 Settlement and Volume Change: The on- and off-site fills and paralic deposits are subject to consolidation and/or hydro-collapse as a result of increased moisture content that will result in settlement on adjacent improvements. It is our professional opinion that this hazard cannot be reasonably mitigated to an acceptable level. Storm Water Standards Part 1: BMP Design Manual C-14 Appendix C: Geotechnical and Groundwater Investigation Criteria Screening Question Yes No Can Infiltration in any appreciable quantity be allowed without posing significant risk for groundwater related concerns (shallow water table, 7 storm water pollutants or other factors)? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Annendix C.3. Provide basis: The risk of groundwater contamination has not been evaluated at this time. Can infiltration be allowed without violating downstream water 8 rights? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: The risk of causing potential water balance issues such as change of seasonality of ephemeral streams or increased discharge of contaminated groundwater to surface waters has not been evaluated at this time. If all answers from row 1-4 are yes then partial infiltration design is potentially Part 2 feasible. The feasibility screening category is Partial Infiltration. Result* If any answer from row 5-8 is no, then infiltration of any volume is considered to NO be 10 be completed using gathered site information and best professional judgment considering the definition —of MEP in the MS4 Permit. Additional testing Ciby City Engineer to substantiate findings groy*s Wilson, CEG #255 1 Storm Water Standards Part 1: BMP Design Manual C-14