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Home My WebLink AboutPD 05-19; FAHR RESIDENCE; REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION; 2005-09-21I I I I I I I I I I I I I I I I I I ·I w CHRISTIAN WHEELER. ENGINEER.ING REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET, LOT 70 CARLSBAD, CALIFORNIA PREPARED FOR: MIKEFAHR POST OFFICE BOX 131446 CARLSBAD, CALIFORNIA 92013 PREPARED BY: CHRISTIAN WHEELER ENGINEERING 4925 MERCURY STREET SAN I)IEGO, CALIFORNIA 92111 4925 Mercury Street+ San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758 PD 05--19· .... ' Cl 0 z ~ 0 Ul :c 0 ·, I. I I I I I I I I I I I I I I I I I I September 21, 2005 Mike Fahr Post Office Box 131446 Carlsbad, California 92013 w CHRISTIAN WHEELER ENGINEER.ING RECEIVED NOV 22 2005 ENGINEERING DEPARTMENT CWE 2050527.02 SUBJECT: REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION, PROPOSED SINGLE-FAMILY RESIDENCE, LOT 70, EL FUERTE STREET, CARLSBAD, CALIFORNIA. Dear Mr. Falir: In accordance with your request, we have completed a preliminary geotechnical investigation for the single- family residence proposed at the subject property. We are presenting herein our findings and recommendations. In general, we found the subject property suitable for the proposed development, provided the recommendations presented herein are followed. Based on our investigation, we have concluded the following: • The site is ultimately underlain by dense to very dense metavolcanic rock and associated sedimentary rock, but is mantled by a two-to three-foot-thick layer of relatively loose surficial soils · that are considered unsuitable in their present condition to support fill and/ or settlement-sensitive improvements. As such, any surficial soil that is not removed by the planned grading will need to be overexcavated in the areas to support fill and/ or settlement-sensitive improvements and be replaced as properly compacted fill. • The site is capped with moderately expansive clayey subsoil. This material will need to be mixed with the sandy portions of the on-site soils to create a nondetrimentally expansive mix prior to being placed as structural fill, or be placed only in landscape areas where no concrete flat work will be constructed. 4925 Mercury Street+ San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758 I I I I -I I I I I I I I I I I I I I -I C\''VE 2050527.02 September 21, 2005 Page No. 2 • Based on the proposed grading plan, the building pad will be underlain by cut ·soils, with fill soils fills of varying thickness. Additionally, we anticipate that although the metavolcanic rock and ,associated sedimentary rock material can be excavated to the proposed depths using heavy grading equipment, it will be difficult to excavate for foundations and/ or utilities in this materiai using lightweight trenching equipment. Based on these conditions, it is recommended that the cut portions of the proposed pads be undercut during grading to mitigate the potential for differential · s.ettlement and so that it will be possible to use normal trenching eqµipment during tl1e construction of tl1e home. • The site is located in an area that is relatively free of geologic hazards that ·will ha-ve a significant effect on tl1e proposed development. 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 Uniform Building Code and other governmental regulations should provide a level of life-safety suitable for the type of development proposed. If you have any questions after reviewing this r_eport, plea_se do not hesitate to contact our office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, CHRISTIAN W'HEELER ENGINEERING Charles H. Christiat~, RGE #00215 CHC:CRB:s_cc cc: (6) Submitted Curtis R. Burdett, CEG #1090 I I I I I. I I I I I I I I I I I TABLE OF CONTENTS PAGE Introduction and Project Description .......... : .................................................................................................... i Project Scope ..........................•...................................................................... : .... , ..............•........................ : .......... 2 · Findings .................................................................................................................................................................. 3 Site Description ........................................... : .................................................................................................... 3 General Geology and Subsurface Conditions ............ : ................................................................................ 3 Geologic Setting and Soil Description ..... , ................................................................................................ 3 Artificial Fill ........................ , ......................................................................... · ............................................ 4 .Residual Soil ................................................................. : .............................. : ............................................. 4 Santiago Peak Volcanics ............................................................................... _ .......................................... 4 Ground\vater ........................................................................................................................................... : ..... 5 Tectonic Setting ............................................................................................................................................ 5 Geologic Hazards ...................... .-...................................................................................................................... 5 Ground Shaking ............................................................. ,. ..................................... : ....................................... 5 Lands-lide Potential and Slope Stability ..................................................................................................... 6 Liquefaction ....................................•...................... , ...................................................................................... 6 Flooding ..... -................................................................................ -.................................................................. 6 Tsunamis .................................................................................................................... -................. : ................. 6 Seiches-................................................................................. -......................................................................... 6 Conclusions ..................................................................................... : ...... -............... ,. ............................................... 7 Recommendations ................................................................................................................................................ 8 Grading and Earthwork .................................................................................................................................. 8 General.. ...................................................................................... · .................................................................. 8 Observation of Grading .............................................................................................................................. 8 Clearing and Grubbing ................................................................................................................................ 8 Site Preparation ................................................................................................ : ........................................... 8 Pad Undercuts ............. : ...........................•............................... : .................................................................... 8 Processing of Fill Areas .................... : ............................. : ............................................................................ 9 Compaction and Method of Filling'. .............................. , ........................................................................... 9 Fill Slope Construction ....................................................... , ....................................................................... 9 Disposal of Oversize Rock ...................................................... : ................................................................ 10 Imported Fill Material ............................................................................................................................... 10 Temporary Slopes ............................................... -......................................................... _. ............................. 10 Surface Drainage ......................................................... _ ............. : .................................................... , ............ 10 Grading Plan Review ................................................................................................................................. 11 Foundations ....................... '. ............................................................................................................................ 11 General.. ............................................................................................................................ · .......................... 11 Exp~nsive_Char~cteristics ............... _ .......................................................................................................... 11 Footing Dunens1ons .............................................................................................................................. : ... 11 Footing Setback .......................................................................................................................................... 11 Bearing Capacity ......................................................................................................................................... 11 Footing Reinforcing ................................................................................................................................... 12 Lateral Load Resistance .......................................................................................................... .' .................. 12 Settlement Characteristics ......................................................................................................................... 12 Foundation Plan Review ..................................... : .................................................. -................................... 12 Foundation Excavatioh Observation ..................................... : .... : ........................................................... 12 Seismic Design Parameters ............................................................................................................................ 12 On-Grade Slabs ............................. .' ................................................................................................................ 13 C\VE 2050527.02 Proposed Single-Family Residence Lo~ 70, El Fuerte Street, Carlsbad, California I I I I I ·1 I I I I I I ··I ·1. I. ,I I I General. ............................................................ · ......... · ................................................................................. 13 Interior Floor Slabs ............................... ..'. .................................................................................................. 13 Moisture Protection fo.r Interior Slabs ...................................................................................... : ............ 13 Exterior Concrete Flatwork ................................... , .................................................................................. 14 Earth Retaining \Valls .................................................................................................................................... 14 Foundations .......................................................................................................... · ...................................... 14 Passive Pressure ........................................................................ , ...................................... : .......................... 14 A·ctive Pressure .......................... , ........... J .................................................................................................... 14 Waterproofing and Subdrain ................................ '.. .................................................................................. 15 Backfill .............................................................. · .. · ....................................................................................... 15 Soluble Sulfates ........................................................................................................................ : ...................... 15 Limitations ........................................................................................................................................................... 15 Revie\v, Observation and Testing ......................... , ................................. : .................................................... 15 Uniformity of Conditions ....................................................................................................... : ..................... 16 Change in Scope ............................................. : ............................................................................................... 16 Time Litnitations ............................................................................................................................................ 16 Professional Standard .................................................................................................................................... 16 Client's Responsibility ....................................................................... _ ............................................................. 17 Field Explorations .............................................................................................................................................. 17 · Laboratory Testing ................................................................................................. .' ............................................ 17 CWE 2050527.02 Proposed Single-Family Residence Lot 70, El Fuerte Street, Carlsbad, California I I I I 1·. 1· I I· I ·1 I I I I ·I I I ATTACHMENTS TABLES Table I Table II Maximum Bedrock Acceleration, Page 6 Seismic Design Parameters, Page 13 FIGURES Figure 1 PLATES Plate 1 Plates 2-4 'Plate 5 Plate 6 APPENDICES Appendix A AppendixB Site Vicinity Map, Follows ·Page 1 Site Plan & Geotechnical Map Test Trench Logs Laboratory Test Results Retaining Wall Subdrain Detail References Recommended Grading Specifications-General Provisions CWE 2050527.02 Proposed Single-Family Residence Lot 70~ El Fuerte Street, Carlsbad, California I I I I I I I I I I I I I I I I I I w CHRJSTIAN WHEELER. ENGINEER.ING PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET, LOT 70 APN 215-492-10 CARLSBAD, CALIFORNIA INTRODUCTION AND PROJECT DESCRIPTION This report presents the results of a preliminary geotechnical investigation performed for a proposed single- family residence to be constructed on a vacant lot west of El Fuerte Street, in the La Costa area of the city of Carlsbad, California. Figure Number 1, on the following page, presents a vicinity map showing the location of the property. \Ve understand that a single-family custom home will be constructed on the lot. The main portion of the home will be one and two stories, with a lower level garage tucked under a one-story portion on the southern side of the home. Also, a single-story guesthouse will be constructed to the southeast of the main residential structure. \v'e expect that the main residence will consist of masonry construction for the below grade portions and wood-frame construction for the above grade portions. We also expect that the guesthouse will consist of wood-frame construction and that both buildings will have on-grade concrete floor slabs and will be supported by conventional shallow foundations. Additional improvements will include a driveway that extends to the garage from El Fuerte Street and a swimming pool, gazebo and built-in barbeque in the rear yard. Grading for the proposed home is expected to consist of cuts and fills of about seven feet and ten feet, respectively, from existing grades. Additionally, several site retaining walls are proposed including perimeter retaining walls up to about 10 feet in height along the southern and western property lines, ~nether perimeter retaining wall up to about 6 feet in height near the northern property line, and an interior building retaining wall up to about 13 feet in height between the garage/ guesthouse level and the first floor/ pool level. In order to augment our understanding of the proposed site development, our firm was provided with a preliminary grading plan prepared by LDE Consulting. A copy of this preliminary grading plan has been used as the base for our Site Plan and Geotechnical Map, which is included herein as Plate No. 1. I 4925 Mercury Street+ San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758 I 1· I· I ·1 I I I I I I I I .. I I I I I I North CWE 2050527.02 SITE VICINITY MAP (Adapted from Thomas Brothers Maps) PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET -LOT70 CARLSBAD, C_ALIFORNIA. ·SITE September 2005 Figure 1 I I I I I· I I ·1 I I I I I ·I- I I I C\"Xi'E 2050527.02 September 21, 2005. Page No. 2 This report has been prepared for th~ exclusive use of :Mr. JIJike Fahr, and his design consultants, for specific application to the project described herein. Should the project be modified, the conclusions and recommendations presented in this report shoul? be reviewed by Christian Wheeler Engineering for conformance with our recommendations artd to determine if any ad?itional subsurface investigation, laboratory testing and/ or recommendations ar!;! necessary. Our profes_sional services have been performed, our findings obtained and our recommendations prepared in accordance with generally accepted engineering J?rinciples and practices. This warranty is in lieu of all other warranties, expressed or implied. PROJECT SCOPE 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 cont.amination, recommendations to prevent floor slab moisture intrusion or the formation of mold ,vithin structures, or any other se1vices not specifically described in the scope of services presented below. More specifically, the intent of our proposed investigation is to: a) b) c) d) . e) f) Explore the subsurface conditions of the site to the depths influenced by the proposed cons tructi_on; Evaluate, by laboratory tests, the engineering properties of the various strata that may influei:ice the proposed qevelopment, including bearing capacities, expansive characteristics and settlement potential; Describe the general geology at the site including possible geologic hazards that could have an effect on the site developm~nt, and prov:ide tl1e seismic design parameters as required by ' . the most recent edition of the Uniform Building Code; Address potential construction difficulties that may be encountered due to soil conditions, groundwater or geok>gic hazards, and provide recommertdations concerning tl1ese problems; Develop soil engineering criteria for site preparation and grading,; ~rovide design parameters for unrestrained and restrained retaining walls; I I 1· I I I I I I I I I I :I I C\VE 2050527.02 September 21, 2005 PageNo .. 3 g) h) / Recommend an appropriate foundation system for the type of structures anticipated and develop soil engineering design criteria for the recommended foundation design; Present our professional opinions in this rep or~, which includes in addition to our conclusions and recommendations, a plot plan, exploration logs and a summary of the laboratory test results. Although tests for the presen~e of soluble sulfates were performed as part of the scope of our setvices, it should be understood Christian Wheeler Engineering does not practice corrosion engineering. If such an 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 the$e tests should only be used as a guideline to determine if additional testing and analysis is necessary. FINDINGS SITE DESCRIPTION The subject site is a vacant, rectangular parcel of land located on the west side of El Fuerte Street, in the La Costa area of the city of Carlsbad, California. The lot is identified by Assessor'~ Parcel Number 215-492-10 and, in addition to being bordered by El Fuerte Street to the southeast, is bordered to .the south and west by additional vacant lots (Lots 69 and 71) and to the north by developed residential properties. Topographically, the lot generally slopes moderately towards the south with the on-site elevations ranging from a low of approximately 233 feet neai: the southern property line to a high of approximately 260 feet near the northern property line .. In terms of vegetation, the site is covered by mostly by low-lying weeds with a small amount of brush along the southern property line. GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located near the boundary between the Foothills Physiographic Province and tl1<:: Coastal Plains Physiographic Province of San Diego County. Based on the results of our subsurface explorations and analysis of readily available, pertinent geologic literature, the site was determined to be underlain by a relatively thin layer of fill and/ or residual soils overlying Jurassic/Cretaceous-age metavcolcanic rock minor amounts of associated sedimentary rock. These materials are described below: I I I I I I I .1 I I I I ·I I I I I I· I C\v'E 2050527.02 September 21, 2005 Page No. 4 ~TIFICIAL FILL (Qaf): An approximately two-to five-foot-thick layer of fill material was encountered within our exploratory trenches T-1 and T-3, which were excavated in the northen portion of the site. The fill material consisted of medium brown, clayey sand (SC) and light to medium grayish-brown, silty sand (SM), and was damp to moist and loose to medium dense in consistency. Based on our experience with similar soil types, we expect that in it's existing condition, the fill has a "low" expansion potential, low to moderate. strength parameters, and low to moderate settlement potential. The existing fill is typically variable in consistency and is therefore considered unsuitable to support new fill and/or settlement-sensitive improvements. This material, however, may be incorporated into structural fills provided it is free of organic debris. RESIDUAL SOIL: An approximately two-foot-'thick layer of residual soil was encountered within two of our exploratory trenches. Due to their relatively dun nature, such materials have not been mapped on the Site Plan and Geotechnical Map, included as Plate No. 1 of this report. Within trench T-2, the residual soil cot}sisted of an approximately one-foot-thick layer of medium brown, damp, loose to meaium dense, silty sand (SM) topsoil over an approximately one-foot-thick layer of medium reddish-brown, moist, medium stiff, sandy day (CL) subsoil. Within trench T-3, tl1e residual so~ consisted of an approximat~ly 2-foot-thick layer of the aforementioned subsoil. Based on our laboratory testing and experience with similar soil types·, we expect tl1at tl1e topsoil has a "low" expansi~n potential while the subsoil has a "medium" to "very high" expansion potential. \Ve also expect tl1at both tl1e topsoil and subsoil have low to moderate strengtl1 paramet~rs and low to moderate settlement potential. In their natural state, tl1e ·residual soils are typically v~able in consistency and are therefore considered unsuitable to support fill and/ or settlement-sensitive improvements. These materials, however, may be incorporated into structural fills provided they are free of organic debris and the subsoils are mi.'i:ed witl1 other on-site sandy soils to provide a nondetrimentally expansive soil prior to being placed as fill. SANTIAGO PEAK VOLCANICS (Kjsp): Below the fill and residual soils, the site is ultimately underlain by Jurassic/Cretaceous-age metavolcanic rock and-minor amounts of associated sedimentary rock identified as the Santiago Peak Volcanics. T11e sedimentary rock was noted to consist of medium reddish-brown and light gray, damp, dense to very dense, silty sand (SM) tlrnt was generally moderately- to well-cemented and was moderately fractured in some areas. The sedimentary rock has relatively high strengtl1 parameters and a low expansion potential in its natural and compacted states. The metavolcanic rock was noted to consist of medium reddish.:.brown and medium gray, damp to moist, dense to very dense, silty gravel (GM), witl1 sand and cobble. '.foe sedimentary rock has relatively high strength paranieters and a.low expansion potential in its natural and compacted states. The sedimentary material I I I I I I I . C\VE 2050527.02 September 21, 2005 Page No. 5 and the metavolcanic 1i1aterial are suitable jn their present condition to suppmt fill and/ or settlement- sensitive improvements and may also be used as structural fill. GROUNDWATER: Groundwater was not encountered in any of our subsurface explorations and _we do not anticipate any groundwater related problems during ot after construction. It should be recognized, howev~r, that minor.groundwater seepage problems may occur after development of a site even where none were present before development. These are usually minor phenon;iena· and are often tl1e result of an aiteration of tl1e permeability charac·teristics of the soil, an alteration in drainage patterns and an increase in irrigation water. Based on the permeability characteristics of the soil and the anticipated usage of tl1~ development, it is our opinion that any seepage problems which may occur will be minor in extent. Iris further our opinion that these problems can be most effectively corrected on an individual basis if and when they develop. TECTONIC SETTING: No major faults are known to traverse tl1e subject site but it should be noted that much of So1,1thern California, including ilie San Diego County area is characterized by a series of Quaternary-age I faul( zones which typically consist of several individu~, en echelon faults tl1atgenerally strike in a nortl1erly to I. I I I I I I ·1. I I · northwesterly direction. Some of these fault zones (and the individual faults witl1in ilie .zones) are classified as active while otl1ers are not currently considered to be_ activ(';, according to the criteria of tl1e California Di,jsion of :Mlnes and Geology. Active fault zones are tl1ose which have shown conclusive evidence of faulting during tlie Holocene Epoch (the most tece1_1t 11,000 years). A review of available geologic maps indicates that the ilctive Rose Canyon_ Fault Zone is located . . approximately 10½ kilometers west of the subject site. Other active fault zones in the region that could possibly affect the site include the Newport Ingiewood and Coronado Bank Fault Zones to the west and southwest, respectively, and the Earthquake Valley, Elsinore and San Jacinto Fault Zones to the east. GEOLOGIC HAZARDS GROUND SHAKING: A likely geologic hazard to.affect the site is ground shaking as a result of movement along one of the major active fault zones.mertti~ned above. The ·maximum grounlaccelerations that could affect the site, based on our Deterministic Seismic Hazard Analysis (PSHA), are summarized in the Table I, presented on the following page. 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 eartl1qµake during the life of the proposed improvements. I I I I I ·I I I. I I . 1 ·1 I I I I CWE 2050527.02 September 21, 2005 Page No. 6 TABLE I: MAXIMUM GROUND ACCELERATIONS Fault Zone Distance Maximum Magnitude Maximum Ground Earthqua~e Acceleration Rose Canyon 10.5km 6.9 maerutude 0.25 g Newport-Inglewood 18km 6.9 magnitude 0.17 g Coronado Bank 35km 7.4 magnitude 0.14g Elsinore -T ulian 38km 7.1 maenitude 0.11 g 'Earthquake Valley 63km 6.5 magnitude 0.06g SanJacinto (Anza) 75km 7.2 maenitude 0.07 g LANDSLIDE POTENTIAL AND SLOPE STABILITY: As part of this investigation we reviewed the publication, "Landslide Hazards in the Southern Part of the San Diego Metropolitan Area" by Tan, 1995. This reference is a comprehensive study that classifies San Diego County into areas of relative landslide susceptibility. The subject site is located in Reiative Landslide Susceptibility Area 3-1. Area 3 is considered to be "generally susceptible" to slope failures; Areas within Subarea 3-1 are considered at or near their stability limits due to steep slopes and can be expected to fail locally when adversely modified. Sites within this classification are located outside the boundaries of known landslides but may contain observably unstable slopes that may be underlain by ~eak materials and/ or adverse geologic structure. However, based on the very competent nature of the sedimentary rock that underlies the site and the proposed slope inclinations on- site, it is our professional opinion and judgment that the potential for landsliding at the subject site is low. LIQUEFACTION: The near-surface soils encountered at the site are not considered to be susceptible to liquefaction due to such factors as soil density, grain-size distribution and the absence of shallow groundwat~r co!).ditions . FLOODING: As delineated on the referenced Flood Insurance Rate Maps prepared by the Federal Emergency Management Agency (1051F), the site is located outside of the boundaries of both the 100-year and 500-year flood zones. TSUNAMIS: Tsunamis are great sea waves. produced by submarine earthquakes or volcanic eruptions. The site is not subject to risk from tsunamis. SEICHES: Seiches are periodiC'oscillations in large bodies of water such as lakes, harbors, bays or reservoirs. The site will not be affected by seiches. I I I I I I I I I I I I I I I I I C\'v'E 2050527.02 September 21, 2005 Page No. 7 CONCLUSIONS It is our opinion and professional judgment that no geotechniGal conditions exist on the subject property that would preclude the construction of the proposed residence and impr9vements provided the recommendations presented herein are followed .. The following are the most significant geotechnical conditions to adversely affect the proposed construction: • Our investigation has indicated that the site is ultimately underlain by dense to very dense metavcolcanic rock ·with minor ai;nounts of associated sedimentary rock, but is mantled by an up to seven-foot-thick layer of relatively loose residual soil and fill material that are considered unsuitable .in their present condition to support fill and/ or settlement-sensitive improvements. As such, any surficial soil tl1at is not removed by the planned grading will need to be overexcavated in the areas to support fill and/ or settlement-sensitive improvements and be replaced as properly compacted fill. • The sit~ is capped with moderately ei.-pansive clayey .subsoil. This material will need to be n;iixed with the sandy portions of the on-site soils to create a nondetrimentally expansive mix prior to being· placed as struc~ral fill, or be placed only in landscape areas where no concrete flat work will be constructed. • Based on the proposed grading plan, the building pad will be underlain by cut soils .and fill soils, with fills of varying tl1ickness. Additionally, we anticipate tl1at although the metavcolcanic rock with minor amounts of associated sedimentary rock can be excavated to the proposed depths using heavy grading ~quipment, it will be very difficult to excavate for foundations and/or utilities in tl1is,material using lightweight trenching equipment. Based on these conditions, it will be necessary to undercut the cut portions of tl1e proposed pads during grading to mitigate the potential for differential settlement and so that it will be possible to us~ normal trenching equipment during the construction of the home. The site is located in an area that is relatively free of geologic hazards that will have a significant effect on the proposed development. The most significant 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 witl1 the requirements of the Uniform l3uilding Code and other governmental regulations should provide a level of life-safety suitable [or the type of development proposed. I I I- I I I I I I I I I I I I -1 I _·1- C\'v.E 2050527.02 September 211 2005 Page No. 8 RECOMMENDATIONS GRADING AND EARTHWORK GENERAL: AU grading should conform to the guidelines presented ln Append.L-.,;: Chapter A33 of the Uniform Building Code, the minimum requirements of City of Carlsbad, and the recommended Grading Specifications and Special Provisions attached hereto, except where specifically superseded in the text of this report. Prior to ·grading, a representative of Christian Wheeler Engineering should be present at the pre-construction meeting to provide additional grading_guidelines, if necessary, and to review the earthwork schedule. 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 e:\.'Posed, and to detennine that the grading proceeds in general accordance with the recommendations contained herein. CLEARING AND GRUBBING: Site grading should begin with the removal of all existing vegetation and other deleterious materials from the portions of the -site that will be graded and/ or will receive improvements. Discin_g of the vegetation into the existing surficial soil is not an acceptable method of brush and grass removal, and may result in the surficial material being unsuitable for use as structural fill. All vegetation and other deleterious debris resulting form the clearing and grubbing should be disposed of off-site. SITE PREPARATION: After clearing and grubbing, the site preparation will generally consist of the removal of unsuitable surficial soils that ar~ not removed by the planned grading and, where necessary to achieve the planned grades, replacing that material a_s properly compacted fill. TI1e removals should extent to the contact with competent sedimentary rock. The sedimentary rock was typically encountered at depths of up to about seven feet below the existing grades, but may be deeper in localized areas. The excavated -material should be replaced as properly compacted fill in accordance with the recommendations presented in the "Compaction and Method of Filling" section of this report. The expansive subsoil should be mixed with the on-site sandy soils to produce a soil mixture with an Expansion Index of less than SO. The areas ~leaned out of unsuitable soils should be approved by the geotechnical engineer prior to replacing any of the excavated soils. PAD UNDERCUTS: Based on the proposed grading, the residence will be supported partially by cut and partially by fill. Additionally, we anticipate that very dense sedimentary rock will be exposed in the cut portions of the building pad. As such, we recommend that the cut portions of the pad be undercut to a CWE 2050527.02 September 21, 2005 Page No. 9 I depth of at least three feet below the pad grade or two feet below the lowest bottom of footing elevation (including retaining wall keyways), whichever depth is greater. This will allow the foundation and on-site I I I I I I I I ·1· I I I I 1· I . utility trenches to be excavated using normal trenching equipment. The overexcavated area should be sloped at an. iodination of at least.two percent towards the south in such a manner that water does not become trapped in the overexcavated zone. The civerexcavated material should be replaced as structural fill, compacted to at least 90 % ~f maximum dry density. · 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 6 inches, moisture conditioned, and compacted to .at least 90 percent relative compaction. COMPACTION AND METHOD OF FILLING: Structural (ill should be compacted to a relative compaction of at least 90 percent of ~aximum dry density as determined by ASTM Laboratory Test D1557- 91. 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 eatth material, free of trash or debris, roots, vegetation, or other materials determined to be unsuitable by our soil technicians or project geologist Fill material should be free of rocks. or lumps of soil in excess of twelve inches in maximum dimensio~. However, in tl1e upper two feet of subgrade, no rocks. or lumps of soil in excess of six inches should be allowed. Based upon the results of our subsurface e..-.,;ploration and laboratory testing, all of tl1e on- site soils_·appear suitable for use as fill materiaL Utility trench backfill witl1in five feet of the proposed structures and beneath driveways, concrete flat\'vork, and pavements should be compacted to a minimum of 90 percent of its !hafiltnum dry density. FILL SLOPE CONSTRUCTION: Based on tl1e preliniipary grading plan, we anticipate.that fill slopes required fo~ tl1e site will be less tl1an 5 feet in height. All fill slopes should be constructed at an inclination of 2:1 or flatter 01orizontal _to vertical). Compaction of slopes should be performed by back-rolling with a sheepsfoot compactor at vertical intervals of four feet or less as the fill is being placed, and track-walking tI;e face of the slope when tl1e slope is completed. As an alternative, the fill slopes may be overfilled by at least tl1ree feet and tl1en cut back to the compacted core at tl1e design line and grade. Fills. should be benched into all temporary slopes and into competent natural soils when tl1e natural slope is steeper than an inclination of 5:1 (horizontal to vertical). Keys should be constructed at tl1e toe of all fill slopes. The keys should extend at least 12 inches into firm natural ground and should be sloped back at least two percent into the slope area. Keys should have a minimum width of 10 feet. I C\VE 2050527.02 September 21, 2005 · . Page No. 10 I DISPOSAL OF OVERSIZE ROCK: Oversize rock in grading operations is defined herein as rocks over 12 inches in diameter. Based on the proposed grading it will be necessary to place oversized material in I I I I I I I I I I I I I· I I I I landscaped areas or to export the material from the site. IMPORTED FILL MATERIAL: Imported soils should be evaluated and approved by the geotechnical cqnsultant prior to being imported. At least two working days notic;e of a potential,import source. should be given to the Geotechnical Consultant so that appropriate testing can be accomplished. The type of material considered most desirable for import is granular material containing some silt or clay binder, which has an expansion index of less than 50, less than 25 percent larger than the. standard #4 sieve, and less than 25 percent finer than the standard # 200 sieve, TEMPORARY SLOPES: We anticipate that temporary excava.tion slopes will les? than about 10 feet in height. For unconfined excavations, the lower 4 feet of the excavation may be.cut vertically and the portions of the excavation above 4 feet should be sloped at an inclination of 0.75:1 (H:V). If deeper excavations are required, specific recommendations will be provided in the field when the soils and site conditions can be identified. Deep, temporary confined excavations, such as for underground utilities, should use sloping sides, shoring, or "trench boxes" during construction, or any otl:ier approved construction technique to ass-qre stability of the excavations. The contractor is solely responsible for designing and constructing stable, temporary excavations and m_ay need to shore, slope, or bench the sides of trench excavations as required to maintain the stability of the excavation sides where the friable sands are exposed. The contractor's "responsible person", as defined in the OSHA Construction Standards for Excavations, 29 CFR, Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety process. In no case should slope height, slope inclination, or exca,1ation depth, including utility trench excavation depth, exceed those specified in local, state, and federal . safety regulations. SURF ACE DRAINAGE: The ground around the proposed structure should be graded so that surface water flows rapidly away from the structure without ponding. In general, we recommend that the ground adjacent to the structure slope ·away at a gradient of at least two percent. Densely vegetated areas where . runoff can be impaired should have a minimum gradient of at least five percent within the first three feet from the structure. Gutters and downspouts should discharge fnto controlled drainage devices. I C\v'E 2050527.02 September 21, 2005 . P~ge No. 11 _ I GR.A.DING PLAN REVIEW: The final gradi1,1g plans should be submitted to this office for review in order to ascertain that the recommendations of this report have been implemented, and that no additional I -I .I I I I .1 I ·1. I I I I recommendations are needed due t9 changes in the anticipated development plans. FOUNDATIONS GENERAL: Based on our findings and engineering judgments, the proposed structure may be supported by conventional continuous and isolated spread footings. The following recommendations are considered the minimum based on soil conditions and are not intended to be lieu of structural considerations. All foundations should be designed by a qualified structural engineer. EXPANSIVE CHARACTERISTICS: Provided the recommendations presented in this report are followed, we anticipate that special foundation design for heaving soils will not be necessary. FOO'J:'ING DIMENSIONS: Itis our opinion that the proposed structur_e may be supported by conventional continuous and isolated spread footings. Spread footings should be embedded at least 18 inches below finish pad grade for one-and two-story portions of the res1dence. Continuous footings should have a minimum width of 12 and 15 inches for one-and two-story portions of the residence, respectively. Isolated spread footings should have a rninhnum width of 24 inches. Retaining wall footings should have a minimum embedment of 18 inches below the lowest adjacent grad_e and should ha~e a minimum width of 24 inches. FOOTING SETBACK: \X-'here the proposed property line retaining wall is proposed at the top of a slope, we recommend that a minimum horizontal setback of 8 feet be provided from the outer edge of the footing to the adjacent slope face. The footing setback-dis_tance from the top of the slope may be achieved by using deepened footings. Footing setback is measured from competent soil and should neglect any loose or soft . . native soils that may occur at the top of a natural slope. Footings planned under the specified setbacks should be provided specific review by the Geotechnical .Consultant prior to construction. BEARING CAPACITY: Spread footings with an embedment of18 inches and a width of 12 inches may be designed for an allowable soil bearing pressure of 2;500 pounds per square foot (psf). This value may be increased by 800 ps f for each additional foot of embedment depth _and 250 psf for each additional foot of width, up to a maximum of 4,000 psf. The bearing value may also be -increased by one-third for combinations of temporary loads such as those due to wind or seismic loads. I C\VE 2050527.02 September 21, 2005 Page No. 12 I · FOOTING REiNFORCING: Reinforcement requirements for foundations should be provided by a sttuctural engineer. However, based on th!'.! expected soil conditions, we recommend that the minimum .1 reinforcing for continuous footings consist of at least two No. 5 bars positioned three inches above the bottom of the footing and two No. 5 bars positioned approximately two inches below the top of the footing. I ·I I· I· I I I ·I I I I . 1 I I I I 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. T11e coefficient of friction between concrete and soil may .be considered to be 0.35. The passive resistance may be considered t? be equal to an equivalent fluid weight of 350 pounds per cubic fopt. 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. SETTLEMENT CHARACTERISTICS: The anticipated total and differential settlement is expected to be . . less than about one inch and one inch qver forty feet, resp!:!ctiv:ely, provided the recommendations presented in this report are followed. It should be recognized that minor cracks normally oGcur 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 nec~ssarily an indication of excessive vertical movements. FOUNDATION PLAN REVIEW: The foundation plans should be submitted to tlus office for review in order to ascertain tl1at the recommendations of tlus .report have been implemented, and tlrnt no additional recommendations are needed due to changes in the anticipated construction: FOUNDATION EXCAVAT_ION OBSERVATION: All footing excavations should be observed by Christian \'(/heeler Engineering prior to placing reinfo;cing steel to determine if tl1e foundation .. recommendations pre·sented herein are followed and iliat ilie foundation soils are as anticipated in the preparation of tlus report. All footing excavations should be excavated neat, level, and square. All loose or unsuitable material should be removed prior to tl1e placement of concrete . SEISMIC DESIGN PARAMETERS Based on a maximum magnitude (Mmax) earthquake of 6.9 along tl1e nearest portion of the offshore segment of the Rose Canyon Fault Zone, the Maximum Ground Acceleration at the site is estimated to be approximately 0.25 g. For structural design purposes, a damping ratio not greater than 5 percent of critical dampening is recommended. Soil Profile Type Sc is recommended (UBC Table 16-J). Based upon the location of the site greater tl1an 10 kilometers from the Rose Canyon Fault Zone (Type B Fault), Near Source C\v'E 2050527.02 September 21, 2005 Page No. l3 I · Factors N. equal to 1.0 and N,. equal to 1.0 .are also applicable. These values, along ,-with other seismically related design parameters from the Uniform Building Code (UBC) 1997 edition, Volume II, Chapter 16, I I I I .I I I I_ I I .1 I I I I utilizing a Seismic Zone 4 are presented in the following table. TABLE II: SEISMIC DESIGN PARAMETERS UBC -Chapter 16 Seismic Recommended Table No. Parameter Value 16-I Seismic Zone Factor Z 0.40 16-T Soil Profile Typ~ Sc 16~Q Seismic Coefficient Ca 0.40N. 16-R Seismic CoefficientC,. 0.56 Nv 16-S Near Soµrce Factor Na. 1.0 16-T Near Source Factor N,-1.0 16-U Seismic Source Type B ON-GRADE SLABS G~NERAL: Itis our understanding that the floor system of the proposed structure and garage will consist of concrete slabs-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. IN"!ERIOR FLOOR SLABS: For conventional sl~bs, the minimum slab thickness should be four inches. (actual) .and the slab should be reinforced with at least No. 3 bars spaced at 18 inches on center each way. Slab reinforce1nent should be supported on chairs such that the reinfoi;cing bars are positioned at mid-height in the floor slab. The slab reinforcement should extend into the perimeter footings at least six inches. The garage slab may be constructe_d independent from the garage perimeter footings, but should have a felt strip between the slab and footing. If the garage slab and footings are constructed monolithically, the reinforcement should extend into the perimeter footing at least six inches. MOISTURE PROTECTION FOR INTERIOR SLABS: Historically, it has been a construction standard to install a moisture/vapor retarder system below interior on-grade slabs where moisture-sensitive floor covering are anticipated. The purpose of the moisture/vapor retarder is to attempt to minimize the · transmission of moisture up through the concrete slab from sources below the slab. It can be noted that there is no known construction method that will in~ure that no moisture will migrate up though on-grade floor slab, and that there will always be some amount of moisture migration into the air space above on-grade floor slabs. I I .I. I I I I I 1· I I I I I I I ., I- I C\X!E 2050527.02 September 21, 2005 Page No. 14 The industry standard for a moisture/vapor retarder system is to place a four-inch layer of clean, coarse sand or crushed rock beiow on-grade c9ncrete floor slab~. If sand is used, which is the most common subslab material, it should have less than ten percent and five percent passing the No. 100 and No. 200 sieves, respectively, in order to provide a capillary break between the underlying soiLand the concrete slab. In addition, a 15-mil polyethylene membrane, such as Stago-Wrap, should be placed directly over the sand or rock blanket and tl1e slab concrete should be placed directly over the membrane. The membrane should be placed in accordance with the recommendation and consideration of ACI 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". In addition, concrete mixes can be designed to reduce the permeability of the concrete, and tlms, reduce the amoun,t of moisture migration up into the air space above the on-grade concrete slab. If desired, we can provide mi.'>'. design recommendations to help minimize tl1e concrete permeability. EXTERIOR CONCRETE FLATWORK: Exterior slabs should have a minimum thickness of four inches. Reinforcement should be placed in exterior concrete flatwork to reduce the potential for cracking and differential movement. Control joints sho~ld be placed in exterior concrete flatwork to help control the location of shrinkage cracks. Spacing of control joints should be in accordance with the American Concrete Institute specifications. EARTH RETAINING WALLS FOUNDATIONS: Specific recommendations for retaining wall foundations are presented in tl1e "Foundations" section ~f this report.· PASSIVE PRESSURE: The passive pressure for the prevailing.soil conditions may be consider~d to be 350 pounds per square foot per foot of depth. This pressure may be increased one-third for.seismic loading. The . . . L coefficient of friction for concrete to the on-site soil may be assumed to be 0.35 for the resistance to lateral movement. \Vhen combining frictional and passive resistance, the friction should be reduced by one-third. The upper 12 inches of exterior retainin~ wall footings should not be included in passive pressure calculations where abutted by landscaped areas. ACTIVE PRESSURE: The active soil pressur~ for the design of "unrestrained" and "restrained" earth retaining structures with a level, nondetrimentally expansive soil backfill may be assumed to be equivalent to the pressure of a fluid weighing 35 and 55 pounds per cubk foot, respectively. An additional 13 pounds per I ·1 ·1· I I· I I I ·1 I I I I I I I I I I C\'v'E 2050527.02 September 21, 2Q0S Page No. 15 cubic foot should be added to the above value for 2:1 (horizontal to vertic:al) sloping backfill. 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 assume a drained backfill condition. WATERPROOFING AND SUBDRAIN: Waterproofing d~tails should be provided by the project architect.. A suggested wall subdrain detail is provided on the attached Pla:te Number 6. We recommend that the Geotechnical Consultant observe all retaining wall subdrains to verify proper construction. BACKFILL: All backfill soils should be compacted to at least 90 percent re_lative compaction. Expansive or clayey soils with an Expansion Index greater than 75 should not be used for backfill material. The wall should not be backfilled until the masonry has reached an adequate strength. SOLUBLE SULFATES The water soluble sulfate content was determined for representative soil samples from the adjacent sites (Lots 69 and 71) in accordance with California Test .1.fe~hod 417. The results of these tests indicated that the representative soil samples had a soluble sulfate ranging from 0.003 to 0.018 percent. Soils with a soluble sulfate content ofless tl~an 0.1 percent are considered to be negligible and no special recommendations are needed. LIMITATIONS REVIEW, OBSERVATION AND TESTING The .i:ecommendations presented in this report are contingent upon our review of final plans and specificat,ions. 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 Uniform Building Code. It is recommended that Christian \'\'heeler 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 tl1ose anticipated prior to start.of construction. I I I I I I I I I I I I I I I I C\VE 2050527.02 September 21, 2005 PageNo.16 UNIFORMITY OF CONDITIONS The recominendatio~s and opinions expressed in this report reflect our best estimate of the project requ4'.ements based on an evaluation of the subsurface soil conditions encountered at the subsurface ~xploration 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 ~etermine if the recommendations contained herein are appropriate. This should be verified in writing or modified by a written addendum. 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 are dt1e to natural processes or the work of man on this or adjacent pr9perties. In addition, changes in the Standards.-of-Practice and/ or Government Codes may occur. Due to such cha,nges, the fine.lings 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 ofour professional services, we c~mply with that level of care and skill ordinarily exercised by members of our profession curr~ntly practicing under similar conditions and in the same locality. The client recognizes that subsurface conditions may vary from tl10se 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 I I I .I I I I I I I I I I I ·I I I I C\VE 2050527.02 September 21, 2005 Page No. 17 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 con~ulting 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 his represefitative.s, to ensure that the information and reconu~endations 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 thatthe contractor and his subcontractors carry out such recommendations during construction. FIELD EXPLORATIONS Three subsurface explorations were made at the locations indicated on the·attached Plate Number 1 on July 5, 200?. These explorations consisted of test trenches excavated by a Case 580L backhoe using an 18-inch bucket. The fieldwork was conducted under the observati0n of our engineering geology personnel. The explorations were carefully logged when made. The test trench logs are presented on the following Plate Numbers 2 through 4. The soils are described in accordance wit~ t!:ie Unified Soils Classification System. In addition, a verbal textural description, the wet color, the apparent moisture and the density or consistency are 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. Disturbed and "relatively undisturbed" chunk samples of typical aad representative soils were obtained and ' 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. It should IJe noted that the laboratory testing for the subject lot was performed in conjunction with the laboratory testing for the neighboring lots to the south (Lot 69) and west (Lot 71). As such, the test results for all three lots are presented on the attached Plate No. 5. A brief description of the tests performed is presented below: I I 1· I I I I I I I I I ii ·I C\XTE 2050527.02 September 21, .2005 Page No. 18 a) CLASSIFICATION: Field classifications.were verified in the laboratory by visual examination. b) The final soil classifications are in accordance with the Unified Soil Classification System. MOISTURE-DENSITY: In-place moisture contents and dry densities were determined for representative soil samples. This information was an aid to classification and permitted recognition of variations in material consistency with depth. TI1e dry unit weight is determined in pounds per cubic foot, and the in-pla~e moisture c:ontent is determined as a percentage of the soil'$ dry weight. The results are summarized in the attached trench logs. · c) COMPACTION TEST: The qiaximum dry c;iensity and optimum moisture content of typical soils were determined in the laboratory in accordance with ,ASTM Standard Test D-1557, Method A. The results of this test are presented on Plate No. 5. d) DIRECT SHEAR TEST: Direct shear tests were performed on representative samples of the on- site material to determine the failure envelope based on yield shear strength. The shear box was designed to accomm,odate a sample having a diameter of 2.375 inches or 2.50 inch~s and a height of 1.0 inch. The samples were saturated and tested at different vertical loads. The shear stress was applied ·at a constant rate of strain of approxin1ately 0.05 inch per minute. The results of these tests are presented on Plate No. 5. e) EXPANSION INDEX TEST: Expa1:sion Ipdex tests were-performed on remolded representative samples of the on-site soil. The tests were performed on the portion of the sample passing the #4 standard sieve. Each sample was brought to optinmm moisture content and then dried back to a constant moisture content for 12 hours at 230 + 9 degrees Fahrenheit. The specimeq was then compacted in a 4-inch-diameter mold in two equal layers by means of a tamper, then trimmed t~ a final height of 1.inch, and brought to a saturation of ~pproximately 50 percent. The specimen was placed in a consolidom~ter with porous stones at the top and bottom, a total normal load of 12.63 pounds was placed (144.7 ~sf), and the samples were allowed to consolidate for a _period of 10 minutes. The sample was saturated, and the change in vertical movement was recorded until th~ rate of expansion became nominal. TI1e expansion index is reported on, Plate No. 5 as the total vertical displacement times 1000. f) SOLUBLE SULFATES: The s.olul;>le sulfate content ,vas determined for samples of soil likely to be present it the foundation level. The soluble sulfate content was determined in accordance with California Test Method 417. The results are presented Piate No. 5. s!J~ 0 PAD 210 _.,-., - ·} 20· ,s· 10· s· o· 20· GRAPHIC SCALE: 1"-20' •o· PAD 238 FFE 226 LEGEND I IT-3 APPROXIMATE TEST TRENCH LOCATION _Qaf_ ARTIFICIAL FILL OVER SANTIAGO PEAK VOLCANICS KJsp KJsp --SANTIAGO PEAK VOLCANICS GEOLOGIC CONTACT -- NOTE: SURFICIAL SOIL LAYER LESS THAN 2 FEET THICK ARE NOT MAPPED w CHRISTIAN WHEH..ER ENGINEERING 4925 Mercury Street• San Diego, CA 92111 • 858-496-9760 • FAX 858-496-9758 PROPOSED SFR LOT. 70 BY: CHC/SCC/HC DATE: 09-14-05 l JOB NO.: 2050527.2 PLATE NO.: 1 T-3! FFE 254 --~--.FFE 228 PAD 228 N 72-00'X"' ,t" !58.fXJ' CONCRET DRll,£WA Y :/ b<2'26'9" L• 20.23' R• 475.75' I /--. Jl /.J.J cc ;2 ;·~ I I 'AS BUILT' RC( ___ EXP.____ DATE REVIEIIED BY• INSPECTOR DATE w CITY OF CARLSBAD ISHEETSI :f-1 =_-==--=~I-, =_ -==-t-tl =_ -==--==--==--==--==--==--==--==--==--==--==--==--=~I-, =_-==--+=ti=--==-...,j,tf--==--=1+1 =_ -=:j--11 !GRADING PLAN~N:~E::~ ;~p;~;;:TST 4 OWNER RESIDENCE 1----+---+--------------11---+--+---+----1 I TITLE SHEET t-----,--+-----------------t---t---+--+---t I=~~ PE 1111/DD/YYYY 1-----1--+----------------+---l---+--+---tiCITY ENGINEER PE EXPIRES DATE I DATE INITIAL OATE INITIAL DATE INITIAL g:D BJ~.~ I PROJECT NO. I DRAWING NO. ENGINEER Of WORK REVISION DESCRIPTION OTHER APPROVAL CITY APPROVAL RVWD BY; __,,!SS,___ PROJECT NO. DRAV.,NG NO. Li, I I I I I I I I I I I I I ·I· ·1 LOG OF TEST TRENCH NUMBER T-1 Date! Excavated: 7/5/2005 Equipment: . Existing Elevation: Case 580L Backhoe Finish Elevation: ..... 1 ..... 2 ..... 3 SUMJ\1ARY OF SUBSURFACE CONDITIONS Artificial Fill (Qaf): Medium brown, damp, loose, CLAYEY SAND (SC), with cobbles. Sedimentary R~ck Associated w / Santiago Peak Volcanics (KJsp): Medium reddish-brown and light gray, damp to moist, medium dense. to dense, SILTY SAND (S:M), fine to. medium-grained. .At 5 feet becomes dense to very dense. Logged by: Project Manager: Depth to Water: Drive Weight: SAMPLES CK CK TSW CHC N/A N/A 10.8 118.6 Well cemented from 5 to 6 feet. CK · 3.9 144.9 6.i---~1----------------------------11---1--i---+--.... ---'"----.I Test trench terminated at 6 feet. I- .... 7 ..... 8 ..... 9 --10 Lc.--'---------------------------L----L..-.L---.1..--..l.-----L-__,J ··~t1~ rfi "' - CH""ISllAN WHEELE"" ENGINEERING BY: .JOB NO.: :PROPOSED SINGLE-FAMILY RESIDENCE El Fuerte Street,. Lot 70, Carlsbad, California HF DATE: September 2005 · 2050527 PLATE NO.: 2 ·1 I I I I I_ I I -_I I I I I I I .I 'I I .. LOG OF TEST TRENCH NUMijER T-2 n·ate Excavated: 7/5/2005 Equipment: Case 580L Backhoe Existing Elevation: Finish Elevation: 'Z' Q) ~ .____.. p P--1 i:r:i Q CJ. 0 H u H ::r: P--1 ~-. . c., SUMMARY OF SUBSURFACE CONDITIONS Topsoil/Artificial Fill (Oat): Medium brown, damp, loose to medium dense, SILTY SAND (SM), with_cobble. Subsoil: Medium to dark reddish-brown, moist, medium stiff, Logged by: Project Manager: Depth to Water: Drive Weight: SAMP LES z i:r:i 0-.:;-~ ~ 0 :::4 ~~ .J:I:i H p:: 0 f-i i;l: i:o i:r:i ..9 ~ z~ i:r:i (/) P--1 TSW CHC N/A N/A ~ ~ ,--.. ~ ~ 13 ~ 0 (/) ~Q f-i f-i 0 z u ~ ~ ~ os (/) 0 f-i H ~ j -0 ~ Q I SANDY CLAY (CL). I-2 ---------.,_....._ _____________ ___, __________ t--+-+----------~ .. -4 -· 5 - .. 6 .. .... 7 I-8 -9 --10 Sedimentary Rock Associated w / Santiago Peak Volcanics (R;:Jsp): .Medium reddish-brown with gray, moist, medium dense to dense, SILTY SAND (S:M), fine to medium-grained. At 4 feet becomes dense. At 5 feet becomes well cement~d. Test trench terminated ;it 8 feet. CK 4.3 147.9 CK !N PROPOSED SINGLE-FAMILY RESIDENCE El Fuerte Street, Lot 70, Carlsbad, California CHRISTIAN WHEELER. BY: HF DATE: September 2005 ENGINEERING JOB NO.:. 2050527 PLATE NO.: 3 I I I I I I I I I ·I I I ·I I I I LOG OF TEST TRENCH NUMBER T-3 Date Excavated: 7/5/2005 Equipment: Case 580L Backhoe · Existing Elev:ation: Finish Elevation: SUMMARY OF SUBSURFACE CONDITIONS 1 2 3 Artificial Pill (Qaf): Light to medium grayish-brown, damp to moist, loose to medium dense, SILTY SAND (SM). Logged by: Project Manager: Depth to Water: Drive Weight: LES SAMP ~ z ~ O,,..._ ..... ...., ~ ~i ~ ~ 0 ~ ;;: p... ~ ~ ..9 ~ z~ ·< ~ C/J p... CK CK TSW CHC NIA N/A ~ -~ ~ ~ 0 ~ ~Q ~ C/J f--i ::J z u C/J E--< 0 -& ~ (/) 0 f--i H ~ j 0 ~ Q 9.9 108.7 .9.4 118.4 4~ 5 177,77;1------------'----------------'---'---1f----lHl+Hl---l---+---+----l 6 7 8 9 TO Subsoil: :Medium to dark reddish-brown, moist, medium stiff,. SANDY CLAY (CL),. Santiago Peak Volcanics (K[sp): Medium reddish-brown and medium gray, moist, dense to very dense, SILTY GRAVEL (GM), .. with sand and cobbles. Test trench terminated at 10 feet. CK· CK .,, PROPOSED SINGLE-FAMILY RESIDENCE El Fuerte Street, Lot 70, Carlsbad, ·California CHR..1S1lAN WHEELER. BY: HF DATE: September 2005 ENGINEERING JOB NO.: 2050527 PLATE NO.: 4 I I I I I I I -I LABORATORY TEST RESULTS PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET, LOT 70 CARLSBAD, CALIFORNIA MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT (ASTM D1557) Sample Location Sample Description Naximum Density . Optimum :Moisture Trench T-1@2'-7' (Lot 69) Reddish-brown, SM 124.0 pcf 12.0% DIRECT SHEAR (ASTM D3080) Sample Location Sample_ Type Fi-iccion Angle Cohesion Trench T-1@2'-7' (Lot 69) · Remolded to 90 % 28 ° 300 psf Trench T-1@ 5'-9' (Lot 71) Reddish-brown, SI\.f 119.2 pcf 11.8 % Trench T-1@5'-9' (Lot 71) R,emolded to 90 % 31 ° 300 psf I EXP ANSI ON INDEX (ASTM _D4829) I I I I I I I I· I Sample _Location Initial I\Ioisture Initial Dry Density Final Moisture Expansion Index Trench T-1 @ ½'-2' (Lot 69) 13.0% 93.0 pcf 32.7% 63 (medium) Trench T-1@3½'-5' (Lot 71) 14.6% 98.7 pc£ 32.6% 120 (very· high) SOLUBLE SULFATES (CALIFORNIA TEST 417) Sample Location Soluble Sulfate C\'<'E 2050527.02 Trench T~1@2'-7' (Lot 69) 0:018 % (SO~) Trench T-1@0-3½' (Lot 71) 0.003 % (SO~) Sept~mber 2005 Plate No. 5 I I ·I I I . 1 ·I I I I I I I- I .I I -1 % Slope Minimum [ 6-inch Minimum 3 / 4 inch Crushed Rock or Mirafi G 1 00N or Equivalent Geofabric Completely Wrapped Around Rock Minimum 4-inch Diameter Perforated Pipe PVC Schedule 40 6-inch Max. r==~ • '(J 1--. .., ·: ~~-. : . < ... . " . '()' . . . .... ~ . -~. -~ . . "· V .. . -1211 ' . ..... . ..; ~-... . I· ... ..,. 10· ·. I -: ( I.Y IY Waterproof Back of Wall Per Architect's Specifications Top of Ground r o, Concrere S~b RETAINING WALL SUBDRAIN DETAIL No Scale L 6-inch Minimum I. .-------'--~---r--------------------1 -!~_~, -PROPOSED SINGLE-FAMILY RESIDENCE ff El Fuerte .Street, Lot 70, Carlsbad, California I C~~ISGT:~E ~ ~~~--L~R_ . BY: HC 4925 MERCCRY STREET I SAN DIEGO, CALIFORNiA 92111 TEI~ (858) 496-9760 FAX. (858) 469-9758 JOB NO.: 205052'7.02 D1\TE: September 2005 PLATE NO.: 6 I I I I I I· I I I. I I I I I I I I C\VE 2050527 .02 September 2005 REFERENCES Appendi....: A, Page A-1 Anderson,J.G.; Ro.ckwell, R.K. and Agne;, D.C., 1989, Past aii.d_ Possible Future Earthquakes of Significance to the San Diego Region, Earthquake Spectra, Volume 5, No. 2, 1989. . Blake, T. F., 2000, Documentation for Eqfault Version 3.0, Thomas F. Blake Computer Services and Sofayare. Boore, David M.,Joyne~, William B., and Fumal,_Thomas E., 1997, "Empirical Near-Sourc<:: Attenuation Relationships for Horizontal and Vertical Components of Peak Ground Acceleration, Peak Ground Velocity, and Pseudo-Absolute Acceleration Response Spectra", in Seismological Research Letters, Volume 68, Number 1,January/February 1997. Countywide Flood Insurance Rate Maps, Panels 1051F, prepared by the Federal Emergency Management Agency, effective date June 19, 1997. Hart, E.W., 1994, Fault-1~.upture Hazard Zones in California, California Division of:Mines and Geology Special Publication 42. Jennings, C.W., 1975, Fault Map of California, California Division of Mines and Geology, Map No. 1, Scale 1:750,000. Kern,.P., 1989, Earthquakes and Faults in San Diego County, Pickle Press, 7J pp. \Vesnousky, S .. G., 1986, "Earthquakes, Quaternary Faults, and Seismic Hazards in California", in Journal of Geophysical Research, Volume 91, No. B12, pp 12,587 to 12,631, November 1986. I I I .I I I I· I I I I I I I I I 1·. C\'<lE 2050527.Q2 September 2005 Appendix B, Page B-1 RECOMMENDED GRADING SPECIFICATIONS -.GENERAL PROVISIONS GENERAL INTENT PROPOSED SINGLE-FAMILY RESIDENCE EL FUERTE STREET, LOT 70 CARLSBAD, CALIFORNIA TI1e intent of these specifications is to establish procedures for clearing, compacting natural ground; preparing areas to be filled, and placing artd 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 Gradiqg 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 thes~ 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 \\!'heeler 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 hi_s representative provide adequate observation so that he ma,y 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 n~f covered by the special provisions or preliminary geotechnical report are encountered during the ~ading operations, the Geotechnical Engineer shall he contacted for further recommendations. If, in the opinion of the Geotecl~nical Engineer, substandard c;oQditions are encountered, such as questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse weather, etc., construttion should be stopped until the conditions are .remedied or corrected or he shall recommend rejection of this work. Tests used to determine the degree of compaction should be performed in accordance with the following .American Society for Testing and Materials test methods: I I I I I I I I I 1· I I I- I I I I. I I C\VE 2050527.02 September 2005 Maximum Density & Optimum Moisture Content -ASTM D-1557-91 Density of Soil In-Place -ASTM D-1556-90 or ASTM D-2922 Appendix B, Page B-2 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 appearance, free from unsightly debris. After clearing or benching the natural ground, the areas to be filled shall be scarified to a depth ~f 6 inches, qrought to the proper moisture content, compacted and tested for the specified minimum degree of compaction. All loose soils in exce.ss of 6 inches tluck shouic;l 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. \Vhen 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 lm.v:er 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 qe benched when considered necessary _by the ~eotechnical 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 described procedure should be backfilled with acceptable soil that is compacted to tl1e requirements of the Geo technical Engineer. This includes, but is not limited to, septic tanks, ~el tanks, sewedines 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 Geotecl-inical 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 _, I I I I I I· I I I I C\v'E 2050527 .02 September 2005 Appendix B, Page B-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 Geotecht:).ical 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 mi.'l:ed 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 effici~ntly applied to achieve· the specified degree of compaction. Each layer shall -be uniformly compacted to tl1e specified minimum degree of dompaction with equipment of adequate size to econo;nica_lly compact the layer. Compaction equipment should either be specifically designed for soil comp~ction 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. \Vhen 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 I '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. I I I 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 Engin('.er's discretion. \Vhen the compaction test indicates that a particular layer is at less tlian the required degree of compaction, the layer shall be reworked to tl1e satisfaction of the Geotechnical Engineer and until the desired relative compaction has been obtained. I I I I I .I I I 1· I I I I I I -I I C\'QE 2050527.02 September 2005 Appendix ~' Page B-4 Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction by sheepsfoot roller shall be at vertical intervals ~f not greater thari four feet. In addition, fill slopes at a ratio of two horizontal to o_ne 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 si.x ·or more inches inward from the finished face of the slope.having a relative compaction of at least 90 percent of maximum dry densify or the degree of compaction specified in the Special Provisions section of this specification. The compaction operation on the slopes shall be continued until the Geotechnical Engineer is of the opinion that the slopes will be surficially stable. pensity 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 w.t;'itten communication from the Geotechnical Engineer or his representative in the form of a daily field report. If the method of achieving the req-qirecl 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. CUTSLO:PES 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 dt1ring gradin~, these conditions shall be analyzed by the Engineering Geologist and Geotechnical Engineer to determine if mitigating measu:i:es 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 governmeqtal 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 G.eotechnical Engineer or bis representative or I I I ·1 .I I I I I :1 I I I I I I I I I CWE 2050527.02 September 2005 Appendix B, Page B-5 the observation and testing shall release the Grading Contra_ctor 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 iepaired before acceptance of work. RECOMMENDED GRADING SPECIFICATIONS -SPECIAL PROVISIONS RELATIVE COMPACTION: The minimµm degree of compaction to be obtained in compacted natural ground, compacted fill, and compacted backfill shall be at least 90 perce~t. For .street and 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 of 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 is 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: \X/here transitions between cut and fill occur "1thin the proposed building pad, the cut portion should be undercut a minimum of one foot below the base of the proposed footings and recort1pacted as structural backfill. In certain cases that would be addressed in the geotechnical report, special footing reinJorcement or a combination-of special footing reinforcement and undercutting may be required.