CHRISTIAN WHEELER E N G I N E E R I N G

Transcription

1 CHRISTIAN WHEELER E N G I N E E R I N G REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SOLTYS RESIDENCE 56 LA GLORIETA RANCHO SANTA FE, CALIFORNIA PREPARED FOR ROBERT AND MICHELLE SOLTYS 038 CAMBRIDGE AVENUE CARDIFF-BY-THE SEA, CALIFORNIA 9007 PREPARED BY CHRISTIAN WHEELER ENGINEERING 3980 HOME AVENUE SAN DIEGO, CALIFORNIA H o m e A v e n u e San Diego, CA FAX

2 CHRISTIAN WHEELER E N G I N E E R I N G August 3, 05 Robert and Michelle Soltys CWE Cambridge Avenue Cardiff By-The-Sea, California 9007 Subject: Report of Preliminary Geotechnical Investigation California Proposed Soltys Residence, 56 La Glorieta, Rancho Santa Fe, San Diego County, Dear Mr. and Mrs. Soltys: In accordance with your request and our proposal dated April 4, 05, 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 residence and associated improvements 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 Daniel B. Adler, RCE # David R. Russell, C.E.G. #5 DBA:drr cc: torrey@eosarc.com H o m e A v e n u e San Diego, CA FAX

3 TABLE OF CONTENTS PAGE Introduction and Project Description... Project Scope... Findings...3 Site Description...3 General, Geology and Subsurface Conditions...4 Geologic Setting and Soil Description...4 Artificial Fill...4 Topsoil...5 Subsoil...5 Torrey Sandstone...5 Groundwater...5 Geologic Structure...5 Tectonic Setting...6 Geologic Hazards...7 General...7 Groundshaking...7 Surface Rupture and Soil Cracking...7 Landslide Potential and Slope Stability...7 Stability Analysis...7 Strength Parameters...8 Method of Analysis...8 Results of Stability Analysis...8 Liquefaction...9 Flooding...9 Tsunamis...9 Seiches...9 Other Potential Geologic Hazards...9 Conclusions...9 Recommendations... Grading and Earthwork... General... Pregrade Meeting... Observation of Grading... Clearing and Grubbing... Site Preparation... Transition Pad Undercut... Fill Slope Construction... Processing of Fill Areas... Compaction and Method Of Filling... Surface Drainage...3 Grading Plan Review...3 Soil Nail Retaining Walls...4 Recommended Earth Design Parameters...4 Soil Nail Tendon Design and Installation...4 Grouting...5 CWE Proposed Soltys Residence 56 La Glorieta Rancho Santa Fe, California

4 TABLE OF CONTENTS PAGE Securing Soil Nails...5 Plan Review...5 Foundation Recommendations...5 General...5 Dimensions...5 Footing Setbacks...6 Bearing Capacity...6 Footing Reinforcing...6 Lateral Load Resistance...6 Settlement Characteristics...6 Expansive Characteristics...7 Foundation Plan Review...7 Foundation Excavation Observation...7 Soluble Sufates...7 Seismic Design Factors...7 On-Grade Slabs...8 General...8 Interior Floor Slabs...8 Under-Slab Vapor Retarders...8 Exterior Concrete Flatwork...9 Masonry Block Earth Retaining Walls...9 Foundations...9 Passive Pressure...9 Active Pressure...0 Waterproofing and Wall Drainage Systems...0 Backfill...0 Reinforced Segmental Block Retaining Walls...0 Limitations... Review, Observation and Testing... Uniformity of Conditions... Change in Scope... Time Limitations... Professional Standard... Client's Responsibility...3 Field Explorations...3 Laboratory Testing...3 TABLES ATTACHMENTS Table I Soil Nail Wall Design Parameters, Page 4 Table II Seismic Design Factors, 03 CBC, Page 8 Table III Geogrid Reinforced Earth Wall Design Parameters, Page CWE Proposed Soltys Residence 56 La Glorieta Rancho Santa Fe, California

5 FIGURES Figure Site Vicinity Map, Follows Page PLATES Plate Site Plan and Geotechnical Map Plate -3 Geologic Cross Sections Plate 4 Keyway Subdrain Detail Plate 5 Cantilever Retaining Wall Subdrain Detail APPENDICES Appendix A Appendix B Appendix C Appendix D Appendix E Subsurface Exploration Logs Laboratory Test Results References Recommended Grading Specifications-General Provisions Results of Gross Stability Analyses CWE Proposed Soltys Residence 56 La Glorieta Rancho Santa Fe, California

6 CHRISTIAN WHEELER E N G I N E E R I N G REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SOLTYS RESIDENCE 56 LA GLORIETA RANCHO SANTA FE, 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 at 56 La Glorieta, in the Rancho Santa Fe community of San Diego County, California. The following Figure Number presents a site vicinity map showing the location of the property. We understand that it is proposed to re-grade the site, as necessary, to accommodate the proposed improvements as well as to satisfy requirements of the County of San Diego pertaining to previous, unpermitted grading at the site. Once re-graded, it is our understanding that a new multi-story, singlefamily residence with a three car garage, swimming pool, patio and hardscape areas, as well as various site walls and other normally associated appurtenances will be constructed at the site. We anticipate that the proposed structure will be of conventional, wood-frame construction with an on-grade concrete floor slab. We also anticipate that the residence and most of the proposed improvements will be supported by conventional, shallow foundations. Depending on the type of swimming pool proposed and its tolerance for deflection, the pool may need to be supported by deep foundations (pier and grade beam system). Planned site grading to accommodate the proposed improvements is expected to consist of cuts and fills of approximately 0 feet and 5 feet from existing site grades, respectively. To assist in the preparation of this report, we were provided with a partial set of architectural plans for the project that were prepared by EOS, grading plans prepared by Coffee Engineering, Inc. as well as various historic building records and topographic maps of the site. A copy of the project grading plan was used as a base map for our Site Plan and Geotechnical Map, included herein as Plate No H o m e A v e n u e San Diego, CA FAX

7 SITE VICINITY OpenStreetMap contributors PROJECT SITE DATE: AUGUST 05 BY: SRD SOLTYS RESIDENCE 56 LA GLORIETA RANCHO SANTA FE, CALIFORNIA JOB NO.: FIGURE NO.: CHRISTIAN WHEELER E N G I N E E R I N G

8 CWE August 3, 05 Page This report has been prepared for the exclusive use of Robert and Michelle Soltys, and their 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 with generally accepted engineering principles and practices. This warranty is in lieu of all other warranties, express 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 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: Excavate ten exploratory test trenches within the portions of the site to be developed to explore the existing soil conditions. Log the existing slope east of the main building pad. Backfill the test trenches with the removed soil. It should be noted that the soil was not compacted and will have to be removed and replaced as compacted fill during the future site grading. 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 that could have an effect on the proposed construction, and provide the seismic design parameters as required by the 03 edition of the California Building Code.

9 CWE August 3, 05 Page 3 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. Perform global stability analyses of the slopes that may affect the proposed improvements. Provide site preparation and grading recommendations for the anticipated work. Provide foundation recommendations for the type of construction anticipated and develop soil engineering design criteria for the recommended foundation designs. Provide recommendations for temporary cut slopes and shoring design, as necessary. Provide design parameters for restrained and unrestrained retaining walls. 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 tests for the presence of soluble sulfates within the soils that may be in contact with reinforced concrete were 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 guideline to determine if additional testing and analysis is necessary. FINDINGS SITE DESCRIPTION The subject site consists of a currently vacant residential lot, identified as Assessor s Parcel Number that is located adjacent and north of the southwest terminus of La Glorieta in the Rancho Santa Fe community of San Diego County, California. It is our understanding that the site formerly supported a single-family residence with associated improvements that included a garage, driveway, and an effluent disposal system. The above grade improvements were destroyed in December of 007 during a fire. Subsequent to the fire the remains of the original structures and associated improvements were demolished and site grubbing and minor grading was performed (Avant, 008). The resulting

10 CWE August 3, 05 Page 4 debris was removed from the site. An SDG&E easement with associated power poles is located along La Glorieta. Topographically, the site is characterized by a relatively level pad within the central portion of the site and an up to 40-foot-high cut and natural slope that descends from the adjacent portions of La Glorieta. This cut slope has an approximate : (horizontal to vertical) inclination. The northwestern portion of the site is characterized by an up to 65-foot-high fill over natural slope that descends from the level building pad to the western perimeter of the lot. This slope has a variable inclination ranging up to about.5: (horizontal to vertical) or flatter. Review of the referenced grading plans indicates on-site elevations ranging from approximately 50 feet along the northern boundary of the property, to approximately 60 feet along La Glorieta. Elevations presented in this report are based on the referenced grading plan (Coffey, 05). We understand that an existing septic tank and at least one vertical seepage pit, which served as the effluent disposal system of the previously existing home on the subject lot, likely remain at the site. Such improvements were not noted during our site visit. Based on our conversations with representatives of EOS, we understand that it is proposed to either utilize the original effluent disposal system if such can be located and it is deemed acceptable by the County of San Diego DEHS, or to install a new effluent disposal system at the site. 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 our subsurface explorations, and analysis of readily available pertinent geologic literature, the site was determined to be underlain by artificial fill material, topsoil, subsoil, and Tertiary-age sedimentary deposits of the Torrey Sandstone. These materials are described below: ARTIFICIAL FILL (Qaf): A wedge of fill material was encountered underlying the majority of the building pad (see Plate Nos. -3). In general, the fill encountered extends to a maximum depth of about 3½ feet below existing grade (trench T-4); however, it exceeds the maximum exploration depth of 4 feet in trench T-3. Where encountered, the artificial fill generally

11 CWE August 3, 05 Page 5 consisted of light brown and brown, damp to moist, silty sand with some gravel (SM). The fill soil consistency is variable and ranges from loose to medium dense. The artificial fill was judged to possess a very low expansion index (EI <0). TOPSOIL: A one-foot-thick topsoil layer was encountered underlying the fill soils in Trench T- 6. This material generally consisted of dark brown, damp, loose to medium dense, silty sand (SM). The topsoil was judged to possess a very low expansion index (EI <0). Topsoil was also observed at the top of the slope located at the eastern side of the existing building pad and is also anticipated in other areas of the site not investigated. SUBSOIL: A ½-foot-thick subsoil layer was encountered underlying the topsoil in Trench T-6. This material generally consisted of reddish-brown, damp, medium dense, clayey sand (SC). The subsoil was judged to possess a low to medium expansion index (EI between and 90). TORREY SANDSTONE (): Tertiary-age sedimentary deposits of the Torrey Sandstone were encountered underlying the surficial soils (fill, topsoil, and subsoil). These formational deposits generally consisted of light brown and grayish-brown, damp, dense, silty sand (SM) and sand with silt (SM-SP). The Torrey Sandstone was judged to possess a very low expansion index (EI <0). GROUNDWATER: No groundwater or seepage was encountered in any of our subsurface explorations. Based on our findings, we do not anticipate that any groundwater-related problems will be encountered either during or after the proposed construction. However, it should be recognized that minor groundwater seepage problems might occur after construction and landscaping at a site even 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 landscaping, 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. GEOLOGIC STRUCTURE: The bedding of Torrey Sandstone exposed along the face of cut slope within the southern portion of the site was measured to dip up to 8 to the northwest (N6 E,

12 CWE August 3, 05 Page 6 8 NW). Such bedding orientation is generally considered to be unfavorable with regards to the south to north sloping slopes on-site. 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 according to the criteria of the California Division of Mines and Geology. Active fault zones are those that have shown conclusive evidence of faulting during the Holocene Epoch (the most recent,000 years). The Division of Mines and Geology used the term potentially active on Earthquake Fault Zone maps until 988 to refer to all Quaternary-age (last.6 million years) faults for the purpose of evaluation for possible zonation in accordance with the Alquist-Priolo Earthquake Fault Zoning Act and identified all Quaternary-age faults as potentially active except for certain faults that were presumed to be inactive based on direct geologic evidence of inactivity during all of Holocene time or longer. Some faults considered to be potentially active would be considered to be active but lack specific criteria used by the State Geologist, such as sufficiently active and well-defined. Faults older than Quaternaryage are not specifically defined in Special Publication 4, Fault Rupture Hazard Zones in California, published by the California Division of Mines and Geology. However, it is generally accepted that faults showing no movement during the Quaternary period may be considered to be inactive. A review of available geologic maps indicates that the active Newport Inglewood -Rose Canyon Fault Zone is located approximately 5½ miles west of the subject site. Other active fault zones in the region that could possibly affect the site include the Coronado Bank Fault Zone to the west, the Palos Verdes Fault Zone to the northwest, and the Elsinore Fault Zone to the east. In addition to active, regional faulting described above, a small, inactive fault is exposed along the face of the cut slope along the southern side of the subject lot. This small fault, which was measured by our engineering geology personnel to display up to 30 inches of vertical offset, is overlain by unfaulted residuum along the top of the cut slope. Given the apparent inactivity of this small fault, no structural offsets from this fault (see Plate No. ) are considered necessary or recommended.

13 CWE August 3, 05 Page 7 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 use of the site for residential purposes are known to exist. In our professional opinion and to the best of our knowledge, the site is suitable for the proposed improvements. GROUNDSHAKING: The most likely geologic hazard to affect the site is ground shaking as a result of movement along one of the major, active fault zones mentioned above. 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. SURFACE RUPTURE AND SOIL CRACKING: The site is not within an Alquist-Priolo Earthquake Fault Zone, and it is our professional opinion that no active or potentially faults are present at the subject site proper so the site is not considered susceptible to surface rupture. LANDSLIDE POTENTIAL AND SLOPE STABILITY: The Relative Landslide Susceptibility and Landslide Distribution Map of the Encinitas Quadrangle prepared by the California Division of Mines and Geology (Tan and Giffen, 995) indicate that the site is situated within Relative Landslide Susceptibility Area 3-. Area 3- is considered to be generally susceptible to slope failures. As part of our scope of services, we have performed quantitative slope stability analyses of the proposed site configuration. STABILITY ANALYSIS: To analyze the stability of the site, three cross-sections were drawn perpendicular to the slopes at the site. These cross-sections, labeled as A-A through B-B are presented on Plate Nos. and 3 of this report. The results of the stability analyses are presented in Appendix E. As described above in the Geologic Setting and Soil Description section of this report, the site is underlain by Tertiary-age materials of the Torrey Sandstone that are overlain by artificial fill. Due to the adversely oriented bedding of the Torrey Sandstone with regards to the north descending slopes on-site, our slope stability analyses have been performed incorporating both block-type and

14 CWE August 3, 05 Page 8 circular-type modes of failure. As presented herein, the minimum factor-of-safety that is considered stable is.5. STRENGTH PARAMETERS: The strength parameters and unit weights for the materials comprising the on-site slopes were estimated based on the results of direct shear testing and our experience with similar soil types in the vicinity of the site. Since the materials of the Torey Sandstone that underlie the site were observed to display out-of-slope bedding orientations, our stability analyses have been performed incorporating anisotropic soil strength parameters for the Torrey Sandstone. It is our professional opinion that the strength parameters and unit weights presented below and utilized in our stability analyses provide for conservative slope stability analyses. Soil Type Unit Weight, Phi, Cohesion, c Artificial Fill (Qaf) 0 pcf psf Torey Sandstone () 5 pcf psf across bedding Torey Sandstone () 5 pcf psf along bedding METHOD OF ANALYSIS: The analyses of the gross stability of the site were performed using Version of the GSTABL7 computer program developed by Garry H. Gregory, PE. The program analyzes circular, block, specified, and randomly shaped failure surfaces using the Modified Bishop, Janbu, or Spencer s Methods. The STEDwin computer program, developed by Harald W. Van Aller, P. E., was used in conjunction with this program for data entry and graphics display. The proposed topographies of the subject site and adjacent areas along geologic cross sections A-A through C-C were analyzed for circular-type and Block-type failures. Each failure analysis was programmed to run at least,000 random failure surfaces. The most critical failure surfaces from each analysis were accumulated and sorted by value of the factor-of-safety. After the specified number of failure surfaces were successfully generated and analyzed, the ten most critical surfaces were plotted so that the pattern may be studied. RESULTS OF STABILITY ANALYSIS: The results of our stability analyses indicate that the reconstructed fill slope to the north of the proposed building pad will demonstrate a minimum factor-ofsafety of.7 against gross failure. However, the steep cut slope that exists along the south side of the

15 CWE August 3, 05 Page 9 proposed building pad demonstrates a minimum factor-of-safety of. against gross failure (See Appendix E). As described below (page 0), it will be necessary to stabilize this cut slope with either a soil nail wall or another retaining wall constructed along the toe of the slope that is of sufficient height to allow for a : (H:V) sloping backfill condition. LIQUEFACTION: The near-surface soils encountered at the site possess a low risk potential for liquefaction due to such factors as soil density, grain-size distribution, and the absence of shallow groundwater conditions. FLOODING: The site is located outside the boundaries of both the 00-year and the 500-year floodplains according to the maps prepared by the Federal Emergency Management Agency. 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. OTHER POTENTIAL GEOLOGIC HAZARDS: Other potential geologic hazards such as volcanoes or seismic-induced settlement should be considered to be negligible or nonexistent. CONCLUSIONS It is our professional opinion and judgment that no geotechnical conditions exist on the subject property that would preclude the construction of the proposed residential structure and associated improvements provided the recommendations presented herein are followed. The main geotechnical conditions affecting the proposed construction consist of potentially compressible soils, cut/fill transitions, and existing steep fill and natural slopes. These conditions are discussed hereinafter. The site was found to be underlain by of potentially compressible fill materials, topsoil, and subsoil. In general, the artificial fill comprises a wedge that underlies approximately half of the existing building pad and associated fill slope (see Plates No. -3). As encountered in the trenches, the fill

16 CWE August 3, 05 Page 0 materials extend to a maximum estimated depth of about 5 feet (trench T-3). However, the fill soils may be deeper in areas of the site not investigated. A thin layer of topsoil and subsoil with a combined thickness of about ½ feet was encountered in trench T-6 and may exist in other areas of the site. The potentially compressible soils are considered unsuitable, in their present condition, for the support of settlement-sensitive improvements and will require removal and replacement as compacted fill. It is anticipated that the recommended site preparation will result in cut/fill transitions underlying the proposed building pad. This condition may result in differential settlements detrimental to the proposed structure. In order to mitigate this condition, special grading consideration as described hereinafter is considered necessary. Steep fill, cut, and natural slopes surround the majority of the existing building pad. The site preparation recommendations contained in this report contemplate the removal and replacement of existing slopes on the north side of the pad. It is recommended that the new slopes be constructed at a : (horizontal to vertical) or flatter inclination. The steep cut slope east of the building pad has a relatively low safety factor with respect to gross and surficial stability. The presence of an SDG&E easement at the top of the slope prevents flattening the slope by cutting into it. Therefore, in order to mitigate this condition, it is recommended that a wall be constructed in front of the wall. The wall should extend to a height such that a : (H:V) sloping backfill that daylights at the top of the slope may be constructed. It is anticipated that the wall will have a maximum height of about 5 feet. As an alternative, a soil nail wall may be constructed. Recommendations for both types of walls are provided herein. A swimming pool is proposed as part of the project.. Depending on the type of swimming pool proposed, its location, and its tolerance for deflection, the pool may need to be supported by drilled cast-in-place concrete piers extending into the underlying Torrey Sandstone and connected by grade beams. Pier recommendations will be provided by this office as necessary. 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

17 CWE August 3, 05 Page 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 County of San Diego, 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 removal of all vegetation and other deleterious materials from the portions of the site that will receive settlement-sensitive improvements and new fill soils. This should include all significant root material. The resulting materials should be disposed of off-site in a legal dumpsite. SITE PREPARATION: Following clearing and grubbing, site preparation should continue with the removal of all fill material, topsoil and subsoil that are not removed by planned grading. Based on our subsurface explorations, the maximum removal depth is expected to be about 5 feet below existing grade (trench T-3). Deeper removals may be necessary in areas of the site not investigated. Fill soils associated with our test trenches should also be removed. The horizontal limits of the removals should include the entire site. All areas cleaned out of unsuitable soils should be approved by the

18 CWE August 3, 05 Page geotechnical engineer or his representative prior to replacing any of the excavated soils. The excavated materials, with the exception of the expansive subsoil, can be replaced as properly compacted fill in accordance with the recommendations presented in the Compaction and Method of Filling section of this report. TRANSITION PAD UNDERCUT: It is anticipated that the building pad will have a cut and fill transition, where a portion of the pad will be underlain by the Torrey Sandstone while the remaining portion of the lot will be underlain by newly compacted fill material. It is recommended that the cut portion of the pad be undercut at least 5 feet below finish grade or one foot below the bottom of the proposed footings, whichever is more. The over-excavated soils may be replaced as properly compacted fill. The bottom of all over-excavated areas should be sloped in such a manner that water does not become trapped in the over- excavated zone. FILL SLOPE CONSTRUCTION: It is recommended that all fill slopes be constructed at a : (horizontal to vertical) or flatter inclination. A key should be cut into the competent supporting materials at the toe of the fill slope. The key should be at least twelve feet wide and be sloped back at least percent. The key should extend at least foot into the competent supporting materials. A subdrain is recommended at the heel of the key (see Plate No. 4). Where the existing ground has a slope of 5: (horizontal to vertical) or steeper, it should be benched into as the fill extends upward from the keyways. The benching should remove all loose surficial soils and should create level areas on which to place the fill material. 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 inches, moisture-conditioned, and compacted to at least 90 percent relative compaction. COMPACTION AND METHOD OF FILLING: All 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 D557. 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

19 CWE August 3, 05 Page 3 unsuitable by the Geotechnical Consultant. Fill material should be free of rocks or lumps of soil in excess of twelve inches in maximum dimension. Utility trench backfill within 5 feet of the proposed structures and beneath the driveways and concrete flatwork should be compacted to a minimum of 90 percent of its maximum dry density. The upper twelve inches of subgrade beneath paved areas should be compacted to 95 percent of its maximum dry density. This compaction should be obtained by the paving contractor just prior to placing the aggregate base material. SURFACE DRAINAGE: The drainage around the proposed improvements should be designed to collect and direct surface water away from proposed improvements and the top of slopes toward appropriate drainage facilities. Rain gutters with downspouts that discharge runoff away from the structure 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 recommend that the ground adjacent to structures be sloped away at a minimum gradient of two percent. Densely vegetated areas where runoff can be impaired should have a minimum gradient of five percent for the first five feet from the structure. It is essential that new and existing drainage patterns be coordinated to produce proper drainage. Pervious hardscape surface should be similarly graded 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. GRADING PLAN REVIEW: The final grading 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 recommendations are needed due to changes in the anticipated development plans.

20 CWE August 3, 05 Page 4 SOIL NAIL RETAINING WALLS RECOMMENDED EARTH DESIGN PARAMETERS: Based on the anticipated earth material conditions, we recommend that Soil Nail Tendons be designed using the following preliminary parameters. These values should be considered preliminary and should be verified by pullout testing of soil nail tendons. Post-grouting of nails may be required to achieve design value. TABLE I: SOIL NAIL RETAINING WALL DESIGN PARAMETERS Angle of Internal Friction 30 degrees Apparent Cohesion Total Unit Weight Pull-Out Resistance (allowable) 00 psf 5 pcf 900 psf SOIL NAIL TENDON DESIGN AND INSTALLATION: We recommend that holes drilled for soil nail tendons be at least four inches in diameter. The restraining portion of the soil nail tendons should be assumed to begin at least 0 feet beyond the face of the slope in order to be well below any disturbance of the slope face. Soil nails should be placed in horizontal levels with horizontal and vertical spacing designed by the structural engineer. The soil nails should be extended beyond the potential failure plane or active wedge in order to derive their resistance from beyond this potential failure plane. For design purposes, it may be assumed that the active wedge adjacent to the shoring is defined by a plane drawn at 30 degrees from the vertical extending upward from the bottom of the excavation. This provision is to provide global stability for the soil nail wall as opposed to adequate friction for the tendons. The soil nail excavations may be installed at angles of approximately 5 to 0 degrees below the horizontal. Holes should be cleaned of debris after drilling. Centralizers should be used to center the tendons in the holes. The soil nail excavations should be completely filled with concrete placed by pumping from the tip out. Centralizing devices or other means should be utilized to ensure that tendons are placed in the center of the drilled shafts. Centralizers should adequately support the bar in the center of the drilled hole and should be spaced at a maximum of 5 feet on center along the length of the bar.

21 CWE August 3, 05 Page 5 Where the soil nail cannot be completely inserted, the Contractor should remove the bar and clean or redrill the hole to permit unobstructed installation. When open-hole drilling methods are being used, the Contractor should have hole cleaning tools on-site suitable for cleaning drilled holes along their full length just prior to bar insertion and grouting. GROUTING: The length of drilled hole should be verified and recorded by the Geotechnical Consultant before grouting. Grout should be injected at the low end of the drilled hole and should fill the drilled hole with a dense grout free of voids or inclusion of foreign material. Cold joints should not be used in grout placement. Soil nails should be grouted full length. After placing the grout for soil nails, they should remain undisturbed for the appropriate cure time. SECURING SOIL NAILS: After completion of the soil nail grouting the reinforcing steel for the facing should be constructed and the shotcrete placed. The soil nail should be secured at the face of the shotcrete with a steel bearing plate seated with full bearing on the shotcrete surface and the nut for the soil nail should be hand tightened before the initial set of the shotcrete. The nut should be made wrench tight after the shotcrete has set. PLAN REVIEW: We recommend that the Geotechnical Consultant review the final design plans and specifications prior to submission to reviewing agencies. FOUNDATIONS GENERAL: Based on our findings and engineering judgment, the proposed structure and associated improvements may be supported by conventional continuous and isolated spread footings. The following recommendations are considered the minimum based on the anticipated soil conditions and are not intended to be lieu of structural considerations. All foundations should be designed by a qualified structural engineer. DIMENSIONS: Spread footings supporting the proposed structure and associated improvements should be embedded at least inches or 8 inches below finished pad grade for one-story or two-story construction, respectively. Continuous spread footings should have a minimum width of inches. Isolated spread footings should have a minimum width of 4 inches. Retaining wall footings should be

22 CWE August 3, 05 Page 6 embedded at least 8 inches below lowest adjacent finish pad grade, and should have a minimum width of 4 inches. FOOTING SETBACKS: Footings proposed adjacent to the top of the slopes will need a minimum horizontal setback of 0 feet between the outer lower edge of the footing to the adjacent slope face. The setback distance may be achieved by using deepened footings. Footings planned under the specified setbacks should be provided specific review by the Geotechnical Consultant prior to construction. BEARING CAPACITY: Spread footings with a minimum embedment of inches and a minimum width of inches may be designed for an allowable soil bearing pressure of,500 pounds per square foot (psf). This value may be increased by 700 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. The bearing value may also 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 engineer. However, based on the existing soil conditions, we recommend that the minimum reinforcing for continuous footings consist of at least No. 5 bar positioned three inches above the bottom of the footing and No. 5 bar positioned two inches below the top of the footing. 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 The passive resistance may be considered to be equal to an equivalent fluid weight of 300 pounds per cubic foot. This assumes 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 foundation settlement is expected to be about inch and inch in 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 shrinkage during curing or redistribution of stresses, therefore

23 CWE August 3, 05 Page 7 some cracks should be anticipated. Such cracks are not necessarily an indication of excessive vertical movements. EXPANSIVE CHARACTERISTICS: The anticipated foundation soils were judged to have a very low expansive potential (EI <0). 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 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. FOUNDATION EXCAVATION OBSERVATION: All footing excavations should be observed by a representative of 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. SOLUBLE SULFATES: The water soluble sulfate content of selected soil samples from the site was determined in accordance with California Test Method 47. The results of this test indicate that the soil samples had a soluble sulfate contents of 0.09 percent and 0.09 percent. Soils with a soluble sulfate content of less than 0. percent are considered to be negligible. Therefore, no special requirements are considered necessary for the concrete mix design. SEISMIC DESIGN FACTORS The seismic design parameters applicable to the subject site are provided below. The seismic design parameters were determined in accordance with the 03 California Building Codes.

24 CWE August 3, 05 Page 8 TABLE II: SEISMIC DESIGN FACTORS Site Coordinates: Latitude -7.5 Longitude Site Class D Site Coefficient Fa.09 Site Coefficient Fv.63 Spectral Response Acceleration at Short Periods Ss.09 g Spectral Response Acceleration at Second Period S g SMS=FaSs.3 g SM=FvS g SDS=/3*SMS 0.74 g SD=/3*SM 0.43 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. ON-GRADE SLABS GENERAL: It is our understanding that the floor systems for the proposed residence will consist of concrete slab-on-grade floors. The following recommendations are considered the minimum slab requirements based on the anticipated soil conditions and are not intended to be in lieu of structural considerations. INTERIOR FLOOR SLABS: The minimum floor slab thickness should be 5 inches (actual) and all floor slabs should be reinforced with at least No. 4 reinforcing bars placed at 8 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. 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 into the perimeter foundations at least six 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

25 CWE August 3, 05 Page 9 plastic, in a layer of coarse sand placed directly beneath the concrete slab. Two inches of sand of sand are typically used above and below the plastic, respectively. The vapor retarder should be at least 5- mil Stegowarp or similar material with sealed seams and should extend at least 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 0% passing the Number 00 sieve and less than 5% passing the Number 00 sieve. The membrane should be placed in accordance with the recommendation and consideration of ACI 30, Guide for Concrete Floor and Slab Construction and ASTM E643, Standards Practice for Installation of Water Vapor Retarder Used in Contact with Earth or Granular Fill Under Concrete Slabs. 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 8 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 8 inches ocew. Driveway slabs should be provided with a thickened edge a least inches deep and 6 inches wide. All slabs should be provided with weakened plane joints in accordance with the American Concrete Institute (ACI) 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. MASONRY BLOCK EARTH RETAINING WALLS FOUNDATIONS: Foundations for any proposed retaining walls should be constructed in accordance with the recommendations for foundations 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. This 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. The upper one foot of soil should be neglected in passive pressure calculations where the footing is abutted by landscaping.

26 CWE August 3, 05 Page 0 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 35 and 55 pounds per cubic foot, respectively. An additional 5 pcf may be assumed for : (horizontal to vertical) sloping backfill conditions. 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. 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 8H 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 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. 5 of this report for informational purposes. Additionally, outlets points for the retaining wall drain system should be coordinated with the project civil engineer. BACKFILL: All 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 backfilled until the masonry has reached an adequate strength. REINFORCED SEGMENTAL BLOCK RETAINING WALLS Reinforced segmental block retaining walls up to about 4 feet high are presently proposed. Provided in the following table are design parameters for Geogrid reinforced segmental block walls.

27 CWE August 3, 05 Page TABLE III: GEOGRID REINFORCED EARTH WALL DESIGN PARAMETERS Reinforced Soil Retained Soil Foundation Soil Angle of internal friction (degrees ) Apparent Cohesion (psf) Unit Weight (pcf) A peak ground acceleration equal to 0.3 g may be assumed for segmental wall design. 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.

28 CWE August 3, 05 Page 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. 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 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.

29 CWE August 3, 05 Page 3 CLIENT'S RESPONSIBILITY It is the responsibility of the clients, or their 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. FIELD EXPLORATIONS Ten subsurface explorations were made at the locations indicated on the site plan included herewith as Plate No. on June 0, 05. These explorations consisted of test trenches excavated with a rubber tire backhoe. The fieldwork was conducted by or under the observation of our engineering geology personnel. The trenches were carefully logged when made. The trench logs are presented in the attached Appendix A. The soils are described in accordance with the 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 either 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. Undisturbed chunk samples and bulk samples of disturbed soil were collected and transported to the 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.

30 B A Qaf Qaf Qaf T- T-0 T-7 Qaf D U T-8 T-9 T-5 Qaf T-3 T-4 Qaf T- C T-6 CWE LEGEND T-0 APPROXIMATE TEST TRENCH LOCATION C' APPROXIMATE GEOLOGIC CONTACT B' APPROXIMATE AREA OF SURFICIAL SLOPE FAILURE C C' GEOLOGIC CROSS SECTION Qaf A' 0 50' 00' ARTIFICIAL FILL UNDERLAIN BY TORREY SANDSTONE TORREY SANDSTONE D U INACTIVE FAULT (DASHED WHERE INFERRED, DOTTED WHERE BURIED BEDDING SCALE: " = 50' SOLTYS RESIDENCE 56 LA GLORIETA RANCHO SANTA FE, CALIFORNIA SITE PLAN AND GEOTECHNICAL MAP DATE: AUGUST 05 JOB NO.: BY: SRD/JDB PLATE NO.: CHRISTIAN WHEELER ENGINEERING