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HomeMy WebLinkAboutCP 05-21; Cazadero Homes; Condo Permit (CP) (2)CHRISTIAN WHEELER ENGINEERING t • • i I I REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION I PROPOSED RESIDENCES r 2817 AND 2819 CAZADERO DRIVE CARLSBAD, CALIFORNIA SUBMITTED TO: CAZADERO HOMES, INC. 2954 HAWKS EYE PLACE CARLSBAD, CALFIORNIA 92009 SUBMITTED BY: CHRISTLVN WHEELER ENGINEERING 4925 MERCURY STREET SAN DIEGO, CALIFORNIA 92111 4925 Mercury Street • San Diego, CA 92111 ^ 8.58-496-9760 FAX 858-496-9758 r June 29,2004 CHRISTIAN WHEELER ENGINEER^ING Cazadero Homes, Inc. 2954 Hawks Eye Place Carlsbad, California 92009 CWE 2040602.1 Attention: Mx. Ron Paul SUBJECT: REPORT OF PREUMINARY GEOTECHNICAL INVESTIGATION, PROPOSED RESIDENCES, 2817-2819 CAZADERO DRIVE, CARLSBAD, CALIFORNIA. Dear Mr. Paul: In accordance witli your request, we have completed a preliminary geotechnical investigation for the subject property. We are presenting herewith our findings and recommendations. No geotechnical conditions were found that would preclude the construction of the proposed residential project provided the recommendations presented in this report are followed. Based on our investigation, we have found tliat the site is underlain by artificial fills and slopewash underlain by Cretaceous-age Santiago Peak Volcanics. The Santiago Peak Volcanics encountered in our investigation are generally medium dense to dense and suitable to support the proposed construction. The existing artificial fill material appears to have been properly compacted and properly benched into competent formational material and is, therefore, considered suitable in its present condition to support settlement-sensitive improvements; however, the upper portions will need to be scarified, moisture conditioned, and recompacted. The existing slopewash material is considered unsuitable in its present condition to support settiement-sensitive improvements. As such, the slopewash will need to be removed and be replaced as properly compacted fill material. This being accomplished, the proposed residences can be supported by conventional spread foundations and with conventional concrete slabs-on-grade. No geologic hazards of sufficient magnitude to preclude development of the site as we presendy contemplate it are known to exist. In our professional opinion and to the best of our knowledge, the site is suitable from a 4925 Mercury Street -f San Diego, CA 92111 • 858-496-9760 • FAX 858-496-9758 C^'E 2040602.1 June 24, 2004 Page No. 2 I I I geologic perspective for tlie proposed constniction, provided die strucmre is designed in accordance ^^'ith tlie requirements of die most recent edition of tlie Uniform BuUding Code and the local govemmental agencies. Ifyou have any questions after reviewing this report, please do not hesitate to contact our office. Tliis oppormnit)' to be of professional ser\'ice is sincerely appreciated. I I I I I i I Respectfully submitted, CHRISTIAN WHEELER ENGINEERING If- Charies H. Christian, R.G.E. #00215 CHC:CRB:scc:shv cc: (6) Submitted Curtis R. Burdett, C.E.G. #1090 TABLE OF CONTENTS PAGE Introduction and Project Description 1 Project Scope 2 Findings 3 Site Description 3 General Geology and Subsurface Conditions 3 Geologic Setting and Soil Description 3 Artificial Fill 4 Slopewash 4 Weathered Undifferentiated Santiago Peak Volcanics 4 Groundwater 4 Tectonic Setting 5 Geologic Hazards 5 Ground Shaking. 5 Surface Rupture 6 Landslide Potential and Slope Stability 6 Liquefaction 6 Flooding. 6 Tsunamis ; 6 Seiches .• 6 Conclusions 7 Recommendations 7 Grading and Earthwork 7 General 7 Observation of Grading 7 Clearing and Gmbbing 8 Site Preparation 8 Building Pad Undercuts 8 Processing of Fill Areas 8 Compaction and Method of Filling 8 Cut and Fill Slope Construction 9 Surface Drainage 9 Temporary Cut Slopes 10 Slope Stability 10 General 10 Erosion Control 10 Foundations 11 General , 11 Foundation Dimensions 11 Bearing Capacity 11 Footing Reinforcement 11 Lateral Load Resistance 11 Setdement Characteristics 11 Foundation Plan Review 12 Foundation Excavation Observation 12 Seismic Design Parameters 12 On-Grade Slabs 13 General 13 CWE 2040602.1 Proposed Residences Cazadero Drive, Carlsbad, California I I I I I I I I I I I I I I r \ I Interior Floor Slabs 13 Moisture Protection for Interior Slabs 13 Exterior Concrete Flatwork 13 Earth Retaining Walls 14 Passive Pressure 14 Equivalent Fluid Pressure 14 Surcharge 14 Waterproofing and Subdrain Observation 14 Backfill 14 Limitations 14 Review, Obser\Tation and Testing. 14 Uniformity of Conditions : 15 Change in Scope 15 Time Limitations 15 Professional Standard 15 Client's Responsibility 16 Field Explorations 16 Laboratory Testing 17 ATTACHMENTS TABLES Table I Maximum Ground Acceleration, Page 5 Table II Seismic Design Parameters, Page 12 FIGURES Figure 1 Site Vicinity Map, Follows Page 1 PLATES Plate 1 Site Plan Plates 2-7 Test Trench Logs Plate 8 Su^ested Retaining WaU Subdrain Detail APPENDICES Appendix A References Appendix B Recommended Grading Specifications - General Provisions CWE 2040602.1 Proposed Residences Cazadero Drive, Carlsbad, Califomia I I I I I I I CHRISTIAN WHEELER ENGINEERING PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED RESIDENCES 2817-2819 CAZADERO DRPyE CARI.SBAD. CALIFORNIA INTRODUCTION AND PROJECT DESCRIPTION This report presents the results of a preliminary geotechnical investigation performed for the proposed residences to be constructed on a previously graded lot located at 2817 and 2819 Cazadero Drive, in the La Costa area of Carlsbad, California. Figure Number 1 presented on the following page provides a vicinity map showing die location of the property. The subject site is a vacant parcel of land located at 2817 and 2819 Cazadero Drive and is identified as Assessor's Parcel Number 215-320-45. The lot has been graded into a relatively level pad that is about six feet above Cazadero Drive. We understand that it is proposed to construct two, single-family residences on the lot The proposed structure on the nordiwest portion of the site will be situated on the existing pad, two-stories in height, and of wood-frame construction. Tlie proposed stmcture on the southeast portion of the site will have split levels with two- and three-story portions, and will have a partially subterranean garage at the front with an interior retaining wall. The above-grade portion of the stmcture will be of wood-frame construction while the retaining portions are expected to consist of masonry block construction. Both sturctures will be supported by conventional shallow spread footings and the lower floors will have on-grade concrete floor slabs. Grading is expected to consist of cuts of about 12 feet from the existing grades and fills of about 5 feet from die existing grades. Tliis report has been prepared for the exclusive use of Cazadero Homes, Inc. and their design consultants for specific application to the project described herein. Should the project be changed in any way, the modified plans should be submitted to Christian Wheeler Engineering for re\tiew to determine their conformance with our recommendations and to determine if any additional subsurface investigation, laboratory testing and/or recommendations are necessary. Our professional services have been performed, our findings obtained and our 4925 Mercury Street ••• San Diego, CA 92111 • 858-496-9760 -•• FAX 858-496-9758 CWE 2040602.1 June 29, 2004 Page No. 2 recommendations prepared in accordance witli generally accepted engineering principles and practices. This warranty is in lieu of all other warranties, express or implied. PROJECT SCOPE Our preliminarj' 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 strucmre, or any other services not specifically described in the scope of services presented below. More specifically, the intent of this analysis was to: a) Explore the subsurface conditions of the site to tlie depths influenced by the proposed construction; b) Evaluate, by laboratory tests and our experience, the engineering properties of the various strata that may influence the proposed construction, including soil bearing capacities, expansive characteristics and settiement potential; c) Describe die general geology at the site including possible geologic hazards tiiat could have an effect on die site construction, and provide the seismic design parameters required by the most recent edition of the Uniform Building Code; d) Address potential construction difficulties that may be encountered due to soil conditions, groundwater, or geologic hazards, and provide recommendations conceming these condidons; e) Develop soil-engineering criteria for the site preparation and grading, and address the stability of cut and fill slopes; f) Recommend an appropriate foundation system for the type of stmcmre anticipated and develop soil engineering design criteria for the recommended foundation design; g) Present our professional opinions diis written report that includes, in addition to our findings and recommendations, a site plan showing the location of our subsurface explorations and a summary of our laboratory test results. I SITE VICINITY MAP (Adapted from Thomas Brothers Maps) PROPOSED RESIDENCES 2817-2819 CAZADERO DRIVE CARLSBAD. CALIFORNIA i North I I I %^JJ*C —.A.ROH 1^ I -M'^ / if/ CWE 2040602.1 June 2004 Figure 1 CWE 2040602.1 June 29, 2004 Page No. 3 It is not within the scope of our services to perform laboratory tests to evaluate the chemical characteristics of the on-site soils in regard to their potentially corrosive impact to on-grade concrete and below grade improvements. If desired, we can submit representative soil samples to a chemical laboratory for analysis. We suggest that such samples be obtained after grading is complete and the soils tiiat can affect concrete and odier improvements are in place. Further, it should be understood Christian Wheeler Engineering does not practice corrosion engineering. If such an analysis is necessary, we recommend that the developer retain an engineering firm that specializes in this field to consult with them on this matter. FINDINGS SITE DESCRIPTION The subject site is an irregular-shaped parcel of land located at 2817 and 2819 Cazadero Drive, in the La Costa area of Carlsbad, California. Tlie subject site is identified as Assessor's Parcel Number 215-320-45, and as Lot 306 of La Costa Meadows Unit No. 2 (Map 6905). The lot is vacant and has been graded to have a relatively level pad in the western portion. An unimproved driveway along the north side of the lot provides access to the pad. There is an approximately 6-foot-high fill slope at the front of the lot and a 12- to 15-foot- high cut slope at die rear of the lot, at the base of a high, gendy ascending natural hillside. The lot is bounded on the north and south by single-family residential properties. The lot has approximately 100 feet of firontage along Cazadero Drive, ranges from approximately 215 to 225 feet in deptii, and has a rear propert)^ line length of about 36 feet. On-site elevations range from a low of approximately 245 feet (MSL) in the west comer, the grade of Cazadero Drive, to a high of approximately 269 feet (MSL), in the southeast corner of the site. A few piles of constmction debris, gravel and cobble were found on the building pad. The building pad area is relatively void of vegetation, wliile the upper, undismrbed portions of the site consist of relatively heavy vegetation comprised of native bmsh. GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject property is located in tiie Footioills Physiograpliic Province of San Diego County. Based upon the results of our limited exploration and analysis of readily available, pertinent geologic and geotechnical literature, we have determined that die site is predominandy underlain byJurassic-Cretaceous-age, undifferentiated Santiago Peak Volcanics that are overlain by man-placed fiH materials in the westem portion and natural slopewash materials in the eastem portion. The soils encountered during our subsurface explorations are described below in order of increasing age: I [ I I ! CWE 2040602.1 June 29, 2004 Page No. 4 ARTIFICIAL FILL (Qaf): A layer of artificial fill was encountered in four of our five subsurface explorations, Trenches T-l through T-4. The estimated limits of the existing fill are shown on the site plan attached as Plate Number 1. In general, the existing fill material is limited to the westem portion of die graded pad and die adjacent fill slope; however, a relatively thin layer of fill was noted in the eastem portion of the graded pad. Witiiin Trench T-3, which was excavated at the westem edge of the graded pad, the fill layer was found to have a thickness ranging from 6 feet at the west end of the trench to 2.5 feet at the east end. Within Trenches T-l, T-2, and T-4, the fill layer was only about six inches thick. The fill material was found to generally consist of grayish- to medium-brown, silty sand (SM) that was tj'pically damp to moist Within Trench T-3, die material was medium dense to dense in consistency. Witliin the Trench T-l, T-2, and T-4, the material was generally loose in consistency. Based on our observation of die fill layer exposed within Trench T-3, it appears that the fill was properly compacted and properly benched into competent formational material. As such, the existing artificial fill material is considered suitable in its present condirion to support settiement-sensitive improvements; however, the upper portions will need to be scarified, moisture conditioned, and reconipacted in accordance with the recommendations presented in the "Site Preparation" section of this report. SLOPEWASH (Qsw): Altiiough not encountered within any of our exploratory trenches, this material was visually obsen^ed in the existing cut slope within the eastem portion of the site. The slopewash deposits consisted of medium to dark brown, silty sands (SM) tiiat were damp to moist and loose to medium dense in consistency. There appeared to be as much as four feet of the slopewash above the undifferentiated Santiago Peak Volcanics within the cut slope, but localized thicker deposits may exist WEATHERED UNDIFFERENTIATED SANTIAGO PEAK VOLCANICS (KJsp): As well as being visually lo^ed on a cut slope within the eastem portion of the site, Jurassic-Cretaceous-^e materials identified as the undifferentiated Santiago Peak Volcanics were encountered within each of our test trenches. The material comprising the Santiago Peak Volcanics consisted of reddish-brown to gray, sandy gravel (GP). Tlie material was damp to moist and medium dense to dense in consistency. The upper few feet of the formational material is moderately to highly firactured. These materials are considered suitable in tiieir present condition to support fill and/or settiement-sensitive improvements. GROUNDWATER: No groundwater was encountered in our explorations and we do not anticipate any significant groundwater related problems during or after constmction provided that proper drainage is maintained However, it should be recognized diat minor groundwater seepage conditions might occur after development of a site even where none were present before development Tiiese are usually minor phenomena and are often the result of an alteration in drainage pattems and/or an increase in irrigation water. Based on die CWE 2040602.1 June 29, 2004 Page No. 5 pemieability characteristics of the soil and the anticipated usage and devdopment, it is our opinion diat any seepage conditions, should diey de\'^dop, will be minor in extent. These potential "nuisance" conditions can tj'pically be mitigated by the use of proper landscaping techniques. TECTONIC SETTING: No faults are known to traverse die subject site. However, it should be noted tiiat much of Southem California, including the San Diego County area, is characterized by a series of Quatemary- age fault zones that consist of several individual, en echdon 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 Califomia Division of Mines and Geology. Active fault zones are those that have shown conclusive evidence of faulting during the Holocene Epoch (die most recent 11,000 years). A review of available geologic maps indicates that the active Rose Canyon Fault Zone is located approximately 12 kilometers southwest of the subject site. Other active fault zones in the region that could possibly affect the site indude the Coronado Bank and San Clemente Fault Zones to the southwest and the Elsinore, Eartiiquake Valley, San Jacinto, and San Andreas Fault Zones to the northeast. GEOLOGIC HAZARDS I GROUND SHAKING: A likely geologic hazard to affect the site is ground shaking as a result of movement along one of die major active fault zones mentioned above. The maximum ground accelerations that would be attributed to a maximum magnitude earthquake occurring along the nearest fault segments of sdected fault zones that could affect the site are summarized in the following Table I. TABLE L MAXIMUM GROUND ACCELERATIONS Fault Zone Distance Maximum Magnitude Earthquake Maximum Ground Acceleration Rose Canyon 12 km 6.9 magnitude 0.18 g Newport-lnglewood 18 km 6.9 magnimde 0.13 g Coronado Bank 36 km 7.4 magnitude 0.10 g Elsinore 37 km 7.1 magnitude 0.07 g Eartiiquake Valley 62 km 6.5 magnitude 0.04 g San Jacinto 74 km 7.2 magnimde 0.05 g CWE 2040602.1 June 29, 2004 Page No. 6 Probable ground shaking levels at die site could range from slight to moderate, depending on such factors as die 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: No active or potentially active faults are present at the subject site so the site is not considered susceptible to surface mpture. LANDSLIDE POTENTIAL AND SLOPE STABILITY: As part of diis investigation we reviewed die publication, "Landslide Hazards in the Southem Part ofthe San Diego Metropolitan Area" by Tan, 1995. This reference is a comprehensive study that dassifies San Diego County into areas of relative landslide susceptibility. The subject site is located in Area 3-1. The Area 3-1 dassification is assigned to areas considered generally susceptible to slope movement. Natural slopes within the Area 3-1 classification are considered at or near their stability limits due to tiieir steep inclinations and can be expected to fail locally when adversely modified. Sites witiiin this classification are located outside the boundaries of known landslides. The site was found to be underlain, bdow the fill layer, by Undifferentiated Santiago Peak Volcanic Rock. Based on our experience, tiiese materials typically have exceEent strengtii characteristics in terms of slope stability. As such, it is our opinion that the potential for deep-seated landsliding on the subject site is low. In addition, it is our opinion diat tiie potential for slope failures within the existing fill slope at the westem side of the subject site is low. This is based on die proper compaction of the existing fill, the proper benching ofthe existing fill into competent formational materials, and the inclination of the fill slope. LIQUEFACTION: The near-surface soils encountered at the site are not considered susceptible to liquefaction due to such factors as soil density, grain-size distribution and the absence of shallow groundwater conditions. FLOODING: Based on our review of the maps prepared by the Federal Emergency Management Agency, the site is located outside the boundary of the 100-year and 500-year floodplains. TSUNAMIS: Tsunamis are great sea waves produced by submarine earthquakes or volcanic emptions. Due to die devation of the site and its location, it should not be affected by a tsunami. SEICHES: Seiches are periodic oscillations in large bodies of water such as lakes, harbors, bays or reservoirs. Due to the site's location, it should not be affected by sdches. CWE 2040602.1 June 29,2004 Page No. 7 CONCLUSIONS No geotechnical conditions were found that would preclude the constmction of die proposed residential project provided die recommendations presented in this report are followed. Based on our investigarion, we have found that the site is underlain by artifidal fills and slopewash underlain by Cretaceous-age Santiago Peak Volcanics. The Santiago Peak Volcanics encountered in our investigation are generally medium dense to dense and suitable to support the proposed constmction. The existing artifidal fiU material appears to have been properly compacted and properly benched into competent formational material and is, therefore, considered suitable in its present condition to support settiement-sensitive improvements; however, the upper portions will need to be scarified, moisture conditioned, and recompacted. The existing slopewash material is considered unsuitable in its present condition to support settiement-sensitive improvements. As such, the slopewash that is not removed by planned grading, will need to be removed and be replaced as properly compacted fill material. In addition, it appears that the front residence will be traversed by a cut/fill transition. Where this occurs, it will be necessary to undercut the cut portion of the building pad. This being accomplished, the proposed residences can be supported by conventional spread foundations and with conventional concrete slabs-on-grade. No geologic hazards of sufficient magnitude to preclude development of the site as we presendy contemplate it are known to exist In our professional opinion and to the best of our knowledge, the site is suitable from a geologic perspective for the proposed constmction, provided the stmcmre is designed in accordance with the requirements of the most recent edition of the Uniform Building Code and the local govemmental agencies. RECOMMENDATIONS GRADING AND EARTHWORK GENERAL: All grading should conform to the guidelines presented in Appendix Chapter A33 of the Uniform Building Code, die minimum requirements of the City of Carlsbad, and the Recommended Grading Spedfications and Special Provisions attached hereto as Appendix B, except where specifically superseded in the text of diis report Prior to grading, a representative of Christian Wheeler Engineering should be present at the preconstruction 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 I I I I I CWE 2040602.1 June 29, 2004 Page No. 8 design criteria to reflect actual fidd conditions exposed, and to determine that the grading proceeds in general accordance with the recommendations contained herein. CLEARING AND GRUBBING: At tiie time of our site investigation, the existing building pad was deared of vegetation, but did support some construction debris. The site preparation should begin with the removal of the constmction debris and any vegetation and other deleterious materials from the portions of site that will be graded and/or will recdve improvements. The resulting materials should be disposed of off-site. SITE PREPARATION: After clearing and gmbbing, the existing slopewash material should be removed from the areas to recdve fill or settiement-sensitive improvements to the contact with underlying materials of the Santiago Peak Volcanics. Based on our limited subsurface explorations, the existing slopewash deposits are expected to have an approximate thickness of four feet, but may be thicker in localized areas. The removals should extend laterally at least five feet outside the building perimeter and at least two feet outside Ught exterior improvements. No otiier special site preparation is considered necessary at diis time. BUILDING PAD UNDERCUTS: It appears tiiat the front residence will be traversed by a cut/fill transition. Wliere tiiis occurs, die cut portion of the building pad should be undercut at least tiiree feet below finish grade. In addition, tiie excavation for the partially subterranean garage may expose very dense hardrock that cannot be excavated with light trenching equipment If this is the case, consideration should be given to undercutting the building pad and utility alleys to at least six inches bdow the bottom of the foundations and utilities and replacing the excavated material with compacted fill material. The bottom of all overexcavated areas should be sloped in such a manner that water does not become trapped in the overexcavated zone. Prior to replacing the excavated materials, the soils exposed at the bottom of the excavation should be scarified to depth of six inches, moismre conditioned and compacted to at least 90 percent relative compaction. PROCESSING OF FILL AREAS: Prior to placing any new fill soils or constmcting any new improvements in areas that have been cleaned out and approved to recdve fill, the exposed soils should be scarified to a depth of 12 inches, moisture conditioned, and compacted to at least 90 percent relative compaction. No other spedal ground preparation is antidpated at this time. COMPACTION AND METHOD OF FILLING: AR stmctural fill placed at tiie site should be compacted to a relative compaction of at least 90 percent of its ma.ximum dry density as determined by ASTNl Laboratory H Test Dl 557-91. FiUs should be placed at or sUghtiy above optimum moisture content, in lifts six to eight inches I I I I I I I I I f I [ [ f I I I I I CWE 2040602.1 June 29, 2004 Page No. 9 thick, witii each lift compacted by mechanical means. Fills should consist of approved eartii material, firee of trash or debris, roots, vegetation, or otiier 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 dimension. However, in die upper two feet of pad grade, no rocks or lumps of soil in excess of six inches should be allowed. The proposed fiUs should be benched at least two feet into all temporary slopes and into competent natural or existing fill soils when the existing slope is steeper than an inclination of 5:1 (horizontal to vertical). A key should be constmcted at die toe of tiie proposed fill slope. The key should extend at least 12 inches into firm natural ground and should be sloped back at least two percent into the slope area. The key should have a minimum width of 5 feet Utility trench backfiU within five feet of the proposed stmcmres and beneath all pavements and concrete flatwork should be compacted to a minimum of 90 percent of its maximum dry density. CUT AND FILL SLOPE CONSTRUCTION: Proposed cut and fill slopes wiU have a maximum height of about 10 feet and are to be constmcted at an inclination of 2:1 or flatter (horizontal to vertical). Care should be taken to make sure that highly expansive materials are not placed within five feet of the face of the fill slope. Compaction of die slope 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 the face of the slope when the slope is completed. As an alternative, the fill slopes may be overfilled by at least three feet and then cut back to the compacted core at the design line and grade. Keys should be made at the toe of fill slopes in accordance with die recommendations presented above under "Compaction and Method of Filling". SURFACE DRAINAGE: Surface mnoff into graded areas should be minimized. Where possible, drainage should be directed to suitable disposal areas via non-erodible devices such as paved swales, gumted brow ditches, and storm drains. Pad drainage should be designed to collect and direct surface water away from proposed stmctures and die top of slopes and toward approved drainage areas. For earth areas, a minimum gradient of one percent should be maintained. The ground around the proposed buildings should be graded so that surface water flows rapidly away from the buildings witiiout ponding. In general, we recommend that the ground adjacent to the building slopes away at a gradient of at least two percent. Densely vegetated areas where mnoff can be impaired should have a minimum gradient of five percent within the first five feet from tiie stmcture. Gutters and downspouts should discharge to controlled drainage systems. CWE 2040602.1 June 29, 2004 Page No. 10 TEMPORARY CUT SLOPES: Temporary cut slopes of up to 12 feet in height are anticipated to be required during the proposed constmction. Ttmpoiziy cut slopes of up to twelve feet in hdght, for retaining walls, can be excavated vertical for the bottom five feet and at an inclination of 0.5 to 1.0 (horizontal to vertical) or flatter above. All temporary cut slopes should be observed by the engineering geologist during grading to ascertain that no unforeseen adverse conditions exist. No surcharge loads such as soil or equipment stockpiles, vehides, etc. should be allowed within a distance from the top of temporary slopes equal to half the slope height Where there is not room to constmct temporary slopes, temporary shoring of the excavation sides may be necessary. The contractor is solely responsible for designing and constmcting stable, temporary excavations and may need to shore, slope, or bench the sides of trench excavations as required to maintain the stability of the excavation sides. The contractor's "responsible person", as defined in the OSHA Constmction Standards for Excavations, 29 CFR, Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety process. Temporary cut slopes should be constmcted in accordance with the recommendations presented in this section. In no other case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety iegulations. SLOPE STABILITY GENERAL: All slopes at tiie subject site ^vill be constmcted at a slope ratio of 2:0 horizontal units to 1.0 vertical unit (2:1) or flatter, with a maximum height of about 10 feet Based on the relatively high strength parameters of tiie on-site soils in their natural and compacted states, it is our opinion that the proposed slopes will be stable in regards to deep-seated slope failure and surficial slope failure. Provided the slope is constmcted in accordance with die above recommendations, it is our opinion that the proposed slope will have a factor of safet}' against failure in excess of the normally required minimum safety factor of 1.5. EROSION CONTROL: The placement of cohesionless soils at the face of slopes should be avoided. Slopes should be planted as soon as feasible after grading. Sloughing, deep rilling and slumping of surfidal soils may be anticipated if slopes are left unplanted for a long period of time, espedally during die rainy season. Irrigation of slopes should be carefiilly monitored to insure that only die minimum amount necessary to sustain plant life is used. Over-irrigating could be extremely erosive and should be avoided. C\X^ 2040602.1 June 29, 2004 Page No. 11. FOUNDATIONS GENERAL: Based on our findings and engineering judgments, it is our opinion that the proposed residences may be supported by shallow conventional contiriuous and isolated spread footings. The following recommendations are considered die minimum based on soil conditions and are not intended to be lieu of stmctural considerations. All foundations should be designed by a qualified stmctural engineer. FOUNDATION DIMENSIONS: Spread footings supporting die proposed two- and three-story stmctures should be embedded at least 18 and 24 inches bdow finish pad grade, respectively. Retaining wall footings should be embedded at least 18 inches bdow finish grade. Continuous should have a minimum width of 15 inches and 18 inches for two- and three-story constmction, respectively. Continuous footings supporting retaining walls and isolated footings should have a minimum width of 24 inches. BEARING CAPACITY: Conventional continuous spread footings with the above minimum dimensions for Kvo-stor)' stmctures may be designed for an allowable soil bearing pressure of 3,500 pounds per square foot Tliis value may be increased by 300 and 700 psf for each addition foot of footing width and embedment, respectively, to a maximum of 5,000 psf This value may also be increased by one-third for combinations of temporary loads such as diose due to wind or sdsmic loads. FOOTING REINFORCEMENT: The project stmctural engineer should provide reinforcement requirements for foundations. However, based on soil conditions, we recommend that the minimum reinforcing for continuous footings consist of at least two No. 5 bars positioned three inches above the bottom of die footing and two No. 5 bars 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 die footing. The coeffident of friction between concrete and soil may be considered to be and 0.35. The passive resistance may be considered to be equal to an equivalent fluid weight of 350 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: Tlie antidpated total and differential settiement is expected to be less dian about one inch and one inch in forty feet, respectively, provided the recommendations presented in this report are followed. It should be recognized that minor cracks normally occur in concrete slabs and C^VE 2040602.1 June 29, 2004 Page No. 12 foundations due to shrinkage during concrete curing or redistribution of stresses, therefore some cracks should be anticipated. Such cracks are not necessarily an indication of excessive vertical movements. FOUNDATION PLAN REVIEW: Tlie foundation plans should be submitted to diis office for review in order to ascertain diat die recommendations of this report have been implemented, and that no additional recommendations are needed due to changes in the anticipated constraction. FOUNDATION EXCAVATION OBSERVATION: All foundation excavations should be observed by die Geotechnical Consultant prior to placing reinforcing steel or formwork to determine if the foundation recommendations presented herein are followed. All footing excavations should be excavated neat, levd, and square. All loose or unsuitable material should be removed prior to the placement of concrete. SEISMIC DESIGN PARAMETERS: Based on a maximum magnimde (Mmax) eartiiquake of 6.9 along the nearest portion of the Rose Canyon Fault Zone, the Maximum Ground Acceleration at the site would be approximately 0.18 g. For stmctural design purposes, a damping ratio not greater than 5 percent of critical dampening, and Soil Profile Type SB are recommended (UBC Table 16-J). Based upon the location of the site being greater than 10 kilometers from the Rose Canyon Fault (Type B Fault), Near Source Factors N» equal to 1.0 and Nv equal to 1.0 are also applicable. These values, along with other seismically related design parameters from the Uniform Building Code (UBC) 1997 edition, Volvime II, Chapter 16, utilizing a Sdsmic Zone 4 are presented in the following table. TABLE II: SEISMIC DESIGN PARAMETERS UBC - Chapter 16 Table No. Seismic Parameter Recommended Value 16-1 Seismic Zone Factor Z 0.40 16-J Soil Profile Type SB 16-Q Seismic Coeffident C, 0.40 N, 16-R Sdsmic Coeffident Cv 0.40 Nv 16-S Near Source Factor Na 1.0 16-T Near Source Factor Ny 1.0 16-U Seismic Source Type B CWE 2040602.1 June 29, 2004 Page No. 13 ON-GRADE SLABS GENERAL: It is our understanding that die proposed residences will use concrete slabs-on-grade. The foUowing recommendations assume tiiat the subgrade soils have been prepared in accordance with the recommendations presented in the "Site Preparation" section of this report. In addition, the following recommendations are considered to be the minimum slab requirements based on the soil conditions and are not intended to be in lieu of stmctural considerations. All slabs should be designed by a qualified stmctural engineer. INTERIOR FLOOR SLABS: The minimum floor slab diickness should be four inches (actual) and all floor slabs should be reinforced with at least No. 3 rdnfordng bars placed at 18 inches on center each way. Slab reinforcement should be supported on chairs such diat die rdnfordng bars are positioned at mid-hdght in the floor slab. The garage slab may be constmcted independent of the garage perimeter footings. However, if die garage slab and footings are poured monolithically, the slab rdnforcement should extend into the perimeter foundations at least six inches. MOISTURE PROTECTION FOR INTERIOR SLABS: It should be noted diat it is die industry standard that interior on-grade concrete slabs be underlain by a moisture retarder. We suggest tiiat dhe subslab moistore retarder consist of at least a two-inch-thick blanket of one-quarter-inch pea gravel or dean coarse sand overlain by a layer of 10-mil visqueen. The visqueen should be overlain by a two-inch-tiiick layer of coarse, clean sand that has less than ten percent and five percent passing die No. 100 and No. 200 sieves. Our e.xperience indicates that this moisture barrier should allow die transmission of firom about six to twdve pounds of moisture per 1000 square feet per day through the on-grade slab. This may be an excess amount of moisture for some types of floor covering. If additional protection is considered necessary, die concrete mix can be designed to help reduce the permeability of the concrete and thus moismre emission upwards through the floor slab. EXTERIOR CONCRETE FLATWORK: Exterior slabs should have a minimum thickness of four inches. Reinforcement and control joints should be constmcted in exterior concrete flatwork to reduce the potential for cracking and movement Joints should 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 spedfications. When patio, walks and porch slabs abut perimeter foundations they should be doweled into the footings. I I CWE 2040602.1 June 29, 2004 Page No. 14 EARTH RETAINING WALLS PASSIVE PRESSURE: Tlie passive pressure for the prevailing soil conditions may be considered to be 350 pounds per square foot per foot of depth. This pressure may be increased one-third for seismic loading. The coefficient of friction for concrete to soil may be assumed to be 0.35 for the resistance to lateral movement. When combining frictional and passive resistance, the friction should be reduced by one-third. The upper 12 inches of exterior retaining wall footings should not be included in passive pressure calculations where abutted by landscaped or unpaved areas. EQUIVALENT FLUID PRESSURE: The active soil pressure for die design of "unrestrained" and "restrained" earth retaining stmctures with level backfill may be assumed to be equivalent to the pressure of a fluid weighing 35 and 55 pounds per cubic foot, respectively. These values assimie a drained backfill condition. SURCHARGE: No surcharge loads have been considered. If any surcharge loads are anticipated, this office should be contacted for the necessary increase in lateral soil pressures. WATERPROOFING AND SUBDRAIN OBSERVATION: The project architect should provide waterproofing details. The geotechnical engineer should be requested to verify that waterproofing has been applied. A suggested wall subdrain detail is provided on the attached Plate Number 8. We recommend that the Geotechnical Consultant be retained to observe all retaining wall subdrains to verify proper constmction. 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. 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 die Geotechnical Consultant and engineering geologist so that they may review and verify their compliance with this report and with the Uniform Building Code. CWE 2040602.1 June 29, 2004 Page No. 15 It is recommended diat Christian Wheeler Engineering be retained to provide continuous soil engineering services during die eartiiwork operations. This is to verify compliance with the design concepts, spedfications or recommendations and to allow design changes in the event tiiat subsurface conditions differ from those antidpated prior to start of constmction. UNIFORMITY OF CONDITIONS The recommendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluation of die subsurface soil conditions encountered at the subsurface e-xploration locations and on the assumption that the soil conditions do not deviate appreciably from those encountered. It should be recognized that die performance of the foundations or temporary slopes might be influenced by undisclosed or unforeseen variations in the soil conditions that may occur in the intermediate and une.xplored 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 Consultant so that he may make modifications if necessary. CFLySIGE IN SCOPE Tliis 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. Tliis should be verified in writing or modified by a written addendum. TIME LIMITATIONS Tlie findings of this report are valid as of this date. Changes in the condition of a property can, however, occur with the passage of time, whether they be due to natural processes or the work of man on this or adjacent properties. In addition, changes in die 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 reKed upon after a period of two years without a review by us verifying the suitabilit)' 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 currendy practidng under similar conditions and in the same locality. CWE 2040602.1 June 29, 2004 Page No. 16 The client recognizes that subsurface conditions may vary firom those encountered at the locations where our borings, sun^eys, 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 diose 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 onfy, 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 fiimishing of oral or written reports or findings. CLIENT'S RESPONSIBIUTY It is the responsibilit)' of the Client, or their representatives to ensure that the information and recommendations contained herein are brought to the attention of the stmcmral engineer and arcliitect 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 liis subcontractors carry out such recommendations during constmction. FIELD EXPLORATIONS Six subsurface explorations were made at the locations indicated on the site plan induded herewith as Plate Number 1 on January 23, 2003. These explorations consisted of six test trenches using a Case 580L Backhoe. The fieldwork was conducted under die observation and direction of our engineering geology personnel. Tlie explorations were carefully logged when made. The test trench logs are presented on the following Plate Numbers 2 through 7. The soils are described in accordance with the Unified Soils Classification. In addition, a verbal texmral 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 "bulk" samples and rdatively undisturbed "chunk" samples were taken from die trench excavations and transported to our laboratory for testing. CWE 2040602.1 June 29, 2004 Page No. 17 LABORATORY TESTING Laboratory tests were performed in accordance with the generaUy accepted American Sodety for Testing and Materials (ASTM) test metiiods or suggested procedures. A brief description of the tests performed is presented bdow. a) CLASSIFICATION: Field dassifications were verified in the laboratory by visual examination. The final soil classifications are in accordance with the Unified Soil Classification System. b) MOISTURE-DENSITY: In-place moisture contents and dry densities were determined for representative soil samples. This information was an aid to classification and permitted recogmtion of variations in material consistency with depth. The dry unit wdght is determined in pounds per cubic foot, and the in-place moismre content is determined as a percentage of the soil's dry weight. The results of diese tests are summarized in the boring logs. c) COMPACTION TEST: The maximum dry density and optimum moisture content of typical soils were determined in die laboratory in accordance with ASTM Standard Test D-1557-91. The result of this test is presented below. Sample Numben Trench T-3 @ 0 - 3' Sample Description: Light yellowish-brown, silty sand (SM) Optimum Moisture Content 10.7 % Maximum Density: 119.0 pcf d) DIRECT SHEAR TEST: A direct shear test was performed to determine the failure envdope of the anticipated foundation soils based on yidd shear strength. The shear box was designed to accommodate a sample having a diameter of 2.375 inches or 2.50 inches and a hdght of 1.0 inch. The sample was tested at different vertical loads and at a saturated moisture content The shear stress was appUed at a constant rate of strain of approximately 0.05 inch per minute. The results of these tests are presented below. Sample Number: Trench T-3 @ 0 - 3' Sample Type: Remolded to 90 % Angle of Intemal Friction: 26° Apparent Cohesion: 300 psf CWE 2040602.1 June 29, 2004 Page No. 18 e) GRAIN SIZE DISTRUBUTION: Tlie grain size distribution of a selected sample was detemiined in accordance witii ASTM D422. Tlie results of these tests are presented below. Sample Location Trench T-3 @0- Sieve Size Percent Passing #4 100 #8 99 #16 97 #30 95 #50 90 #100 62 #200 35 Soil Type SM I - 2 Date Excavated: Equipment: Existing Elevation: Finish Elevation: LOG OF TEST TRENCH NUMBER T-l 1/23/2003 Logged by Case 580 Backhoe 464 feet 466 feet TSW Project Manager CHC Depdi to Water: N/A Drive Weight: N/A 5 Q - 3 - 4 - 5 - 7 - 8 - 9 LlO o u I—I X SUMMARY OF SUBSURFACE CONDITIONS Artificial FiU (Oaf): Grayish-brown, moist, loose, GRiWTELLY ^ ^_ .,SAND(SM). Weathered Undifferentiated Santiago Peak Volcanics (KJsp): Reddish-brown and gray, damp to moist, medium dense to dense, S.\NDY GR.W'EL (GP), moderately to highly fractured. Practical refusal at 4 feet. SAMPLES CK o H w o 4.5 Q 142.7 CHRIST1.\N-WHEELER E N C. I N E F. K 1 N G PROPOSED LA COSTA DUPLEX 2817 & 2819 Cazadero Dr., Carlsbad, Califomia CHRIST1.\N-WHEELER E N C. I N E F. K 1 N G BY: HF DATE: Febmarj' 2003 CHRIST1.\N-WHEELER E N C. I N E F. K 1 N G JOB NO.: 2040602 PL.\TE NO.: 2 LOG OF TEST TRENCH NUMBER T-2 Date Excavated: Equipment: Existing Elevation: Finish Elevation: 1/23/2003 Case 580 Backhoe 464 feet 466 feet Logged by: TSW Project Manager CHC Depdi to Water: N/A Drive Weight: N/A X H a - 4 - 5 - 7 - 9 LlO o I-l u X o SUMNL\RY OF SUBSURFACE CONDITIONS Artificial Fill (Oaf>: Grapsh-brown, moist, loose, SILTi' SAND (SjVI). Weathered Undifferentiated Santiago Peak Volcanics (KJsp): Reddish-brown and gray, damp to moist, medium dense to dense, SANDY GRW^EL (GP). Moderately to highly fractured from Vi to 2'/a feet. At 2V2 feet becomes dense to verv dense. Practical refiisal at 3V2 feet SAMPLES CK o [13 o z e PH D H CO H-1 o 8..-i Q 152.1 CHRISTIAN WHEELER ENCIN 1-: F. R 1 N G PROPOSED LA COSTA DUPLEX 2817 & 2819 Cazadero Dr., Carlsbad, Califomia CHRISTIAN WHEELER ENCIN 1-: F. R 1 N G BY: HF DATE: Febmar>' 2003 CHRISTIAN WHEELER ENCIN 1-: F. R 1 N G JOB NO.: 2040602 PL\TENO.: 3 i Date Excavated: Equipment: Existing Elevation: Finish Elevation: LOG OF TEST TRENCH NUMBER T-3 1/23/2003 Logged by Case 580 Backhoe 464 feet 457.5 feet TSW Project Manager CHC Depdi to Water N/A Drive Weight: N/A X H PH W Q O O U HH X PH o SUMMARY OF SUBSURFACE CONDITIONS S.•^M]'LHS D H on HH Q - 1 Artificial Fill (Oaf); Light gray, moist, medium dense to dense, SILT^' SAND (SM), very fine to fine-grained. 12.6 109.8 MD DS - 4 - 5 - 7 - 9 LlO Medium brown, damp to moist, medium dense to dense, SILTY SAND (SiNJ), with gravd and clay. CK Weathered Undifferentiated Santiago Peak Volcanics (KJsp): Reddish-brown and gray, damp to moist, dense, SANDY ^ GILW^L (GP). Highly fractured from 6-7 feet. Becomes ver\- dense at 7'.j Practical refusal at 7 feet 7.2 10.3.6 CHRISTIAN WHEELER UNGINEEIIING PROPOSED LA COSTA DUPLEX 2817 & 2819 Cazadero Dr., Carlsbad, California BY': HF JOB NO.: 2040602 DATE: Febmar)' 2003 PL.\TE NO.: i I I I I I I I Date Excavated: Equipmenfc Existing Elevation: Finish Elevation: LOG OF TEST TRENCH NUMBER T-4 1/23/2003 Logged by: TSW Case 580 Backhoe Project Manager CHC 464 feet Depth to Water N/A 466 feet Drive Weight: N/A X H [i3 P - 1 - 2 - 3 - 4 - 5 - 7 - 8 - 9 LlO o o I-l u I—I X PH O SUMNL\RY OF SUBSURFACE CONDITIONS Artificial Fill (Qaf): Grapsh-brown, moist, loose, GIL\^TLLY ,SAND(SM). Weathered Undifferentiated Santiago Peak Volcanics (KJsp): Reddish-brown and gray, damp to moist, medium dense to dense, SANDY GR\\TEL (GP). At 3 feet becomes dense to very dense. From 'A to 3 feet becomes moderately to highly fractured. Practical refusal at 3V2 feet S,\i\IPLES I <; 00 CK z H ^ Dd .2 Z & PH D H c/i o 0.8 § PH Q 16.V4 m CHKISTI.AN WHEELER i; N G 1 N E E R. 1 N G PROPOSED LA COSTA DUPLEX 2817 & 2819 Cazadero Dr., Carlsbad, Califomia m CHKISTI.AN WHEELER i; N G 1 N E E R. 1 N G BY: HF DATE: Februar)' 2003 m CHKISTI.AN WHEELER i; N G 1 N E E R. 1 N G JOB NO.: 2040602 PL\TE NO.: 5 i I I i Date Excavated: Equipment Existing Elevation: Finish Elevation: LOG OF TEST TRENCH NUMBER T-5 1/23/2003 Logged by Case 580 Backlioe 464 feet N/A TSW Project Manager CHC Depth to Water: N/A Drive Weight: N/A 5 PH P - 3 - 4 - 5 - 7 - 8 - 9 LlO a o u X p- o SUMMARY OF SUBSURFACE CONDITIONS Weathered Undifferentiated Santiago Peak Volcanics (KJsp); Reddish-brown and gray, damp to moist, dense, SANDY' GR\VEL (GP). Moderately to highly fractured from 0-12 inches. At 12 inches becomes very dense. Practical refusal at 2V2 feet SAMPLES z o tsi ° z e a PH o P 00 H 00 CHRISTIAN WHEELER K N G I N E L R I N G PROPOSED LA COSTA DUPLEX 2817 & 2819 Cazadero Dr., Carlsbad, Califomia BY: HF JOB NO.: 2040602 D.\TE: February2003 PLATE NO.: Date Excavated: Equipment: Existing Elevation: Fimsh Elevation: LOG OF TEST TRENCH NUMBER T-6 1/23/2003 Logged by: TSW Case 580 Backhoe Project Manager CHC 474.0 feet Depth to Water N/A 476.0 feet Drive Wdght: N/A X H PH p o o •-1 u •—I X PH SUMMARY OF SUBSURFACE CONDITIONS S.'\MPLiiS Z o ^ W .2 PH D I-H o P O H 2 - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 LlO Slopewash (Osw); Medium to dark brown, damp to moist, loose to medivim dense, SILTY' SAND (SM), with gravel. Weathered Undifferentiated Santiago Peak Volcanics (KJsp); Reddish-brown and gray, damp to moist, medium dense to dense, SANDY GRW^ (GP). Moderately to highly fractured from 4-7 feet Dense to veiy dense at 7 feet Test trench terminated at 10 feet CHRISTIAN WHEELER ENGINEERING PROPOSED LA COSTA DUPLEX 2817 & 2819 Cazadero Dr., Carlsbad, Califomia CHRISTIAN WHEELER ENGINEERING BY: HF DATE: Febmar)' 2003 CHRISTIAN WHEELER ENGINEERING JOB NO.: 2040602 PLATE NO.: 7 6-inch Miniinum 3/4 inch Cmshed Rock or Miradrain 6000 or Equivalent Waterproof Back of WaU Per Arcliitect's Specifications Top of Ground or Concrete Slab Geofabric Between Rock and Soil T 6-inch Minimum Minimum 4-inch Diameter Perforated Pipe PVC Schedule 40 RETAINING WALL SUBDRAIN DETAIL No Scale CHRISTIAN WHEELER . i ; N G I N n E R. 1 N G •t'-'^s Mi-Rc:LM{YS'niEi.n' S.'\N DIHGC), C.-\J.II-ORNIA rail •I'EL. (K58) 49(,-'mo l-AX. («58) 469-9758 PROPOSED RESIDENCES 2817-2819 CAZADERO DRIVE, CARLSBAD, CALIFORNLV BY: SI IV JOB NO.: 2040602 DATE: June 2004 PL VTE NO.: I I I I r i I CWE 2040602.1 June 29, 2004 Appendix A, Page Al REFERENCES Christian Wheeler Engmeering, Febmary 17,2003, Report of Preliminary Geotechtiical Investigation. Proposed Residential Duplex. 2817-2819 Cazadero Drive. Carlsbad. CaUfomia. Anderson, J.G.; Rockwell, R.K. and Agnew, D.C, 1989, Past and Possible Future Earthquakes of Significance to die San Diego Region, Earthquake Spectra. Volume 5, No. 2,1989. Blake, T.F., 2000, EQFAULT, A Computer Program for the Estimation of Peak Horizontal Acceleration firom 3-D Fault Sources, Version 3.0, Tliomas F. Blake Computer Services and Software, Thousand Oaks, Califomia. Boore, David M., Joyner, WilUam B., and Fumal, Thomas E., 1997, "Empirical Near-Source Attenuation Relationsliips for Horizontal and Vertical Components of Peak Ground Acceleration, Peak Ground Velodty, and Pseudo-Absolute Acceleration Response Spectra", in Sdsmological Research Letters, Volume 68, Number LJanuary/Febmary 1997. CaUfomia Division of Mines and Geology, 1998, Maps of Known Active Fault Near Source-Zones in CaUfomia and Adjacent Portions of Nevada. Federal Emergency Management Agency, 1997, San Diego County, CaUfomia and Incorporated Areas Ho6d Insurance Rate Map, Pand 1051 of 2375, Map Number 06073C1051 F. Hart, E.W., 1994, Fault-Rupture Hazard Zones in CaUfomia, CaUfomia Division of Mines and Geology Spedal PubUcation 42. Jennings, C.W., 1975, Fault Map of CaUfomia, CaUfomia Division of Mines and Geology, Map No. 1, Scale 1:750,000. Kem, P., 1989, Earthquakes and Faults in San Diego County, Pickle Press, 73 pp. Tan, S.S., 1995, LandsUde Hazards in the Northem Part of the San Diego MetropoUtan Area, San Diego County, CaUfornia, CaUfornia Division of Mines and Geology Open-File Report 95-04. Tan, Siang S. and Kennedy, Michael P., 1996, Geologic Maps of the Northwestem Part of San Diego County, CaUfomia, CaUfomia Division of Mines and Geology, DMG Open-File Report 96-02. i I I I i CWE 2040602.1 June 29, 2004 Appendix A, Page A2 Wesnousky, S.G., 1986, "Eardiquakes, Quaternary Faults, and Seismic Hazards in CaUfomia", in Joumal of Geophysical Research, Volume 91, No. B12, pp 12,587 to 12,631, November 1986. TOPOGRAPHIC MAPS County of San Diego, 1960, Map Sheet 342-1695; Scale: 1 inch = 200 feet County of San Diego, 1975, Map Sheet 342-1695; Scale: 1 inch = 200 feet. CWE 2040602.1 June 29, 2004 Appendix B, B-1 RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS PROPOSED RESIDENCES 2817 AND 2819 CAZADERO DRIVB CARLSBAD. CALIFORNL\ GENERAL INTENT The intent of these spedfications is to estabUsh procedures for clearing, compacting natural ground, preparing areas to be fiUed, and placing and compacting fill soils to the lines and grades shown on the accepted plans. The recommendations contained in the preliminary geotechnical investigation report and/or the attached Special Provisions are a part of the Recommended Grading Spedfications and shaU supersede die provisions contained herdnafter in the case of conflict. These specifications shall only be used in conjunction with the geotechnical report for which they are a part. No deviation from these specifications wdl be allowed, except where spedfied in the geotechrucal report or in other written communication signed by the Geotechnical Engineer. OBSERVATION AND TESTING Christian Wheeler Engineering shaU be retained as the Geotechnical Engineer to observe and test the earthwork in accordance with these specifications. It will be necessary that the Geotechiucal Engineer or his representative provide adequate observation so that he may provide his opinion as to whether or not the work was accompUshed as specified. It shall be the responsibiUty of die 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 opiruons. In the event that any unusual conditions not covered by the special provisions or preliminary geotechnical report are encountered during the grading operations, the Geotechnical Engineer shaU be contacted for further recommendations. If, in the opinion ofthe Geotechnical Engineer, substandard conditions are encountered, such as questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse weather, etc., constmction should be stopped until the conditions are remedied or corrected or he shaU recommend rejection of this work. Tests used to detemiine the degree of compaction should be performed in accordance with the foUowing American Sodety for Testing and Materials test methods: CWE 2040602.1 June 29, 2004 Appendix B, B-2 Ma.ximum Density & Optimum Moisture Content - ASTM D-1557-91 Density of Sod In-Place - ASTM D-1556-90 or ASTM D-2922 AU densities shaU be expressed in terms of Rdative Compaction as determined by the foregoing ASTM testing procedures. PREPARATION OF AREAS TO RECEIVE FILL AU vegetation, bmsh and debris derived from clearing operations shaU be removed, and legaUy disposed of. AU areas disturbed by site grading should be left in a neat and finished appearance, free from unsighdy debris. After clearing or benching the natural ground, the areas to be fiUed shaU be scarified to a depth of 6 inches, brought to the proper moisture content, compacted and tested for the specified minimum degree of compaction. AU loose soUs in excess of 6 inches thick should be removed to firm natural ground which is defined as natural soil which possesses an in-sim density of at least 90 percent of its maximum dry density. Wlien the slope of the natural ground receiving fiU exceeds 20 percent (5 horizontal units to 1 vertical unit), the original ground shaU be stepped or benched. Benches shaU be cut to a firm competent formational sod. The lower bench shaU be at least 10 feet wide or 1-1/2 times the equipment width, whichever is greater, and shaU be sloped back into the hdlside at a gradient of not less tiian two (2) percent AU other benches should be at least 6 feet wide. The horizontal portion of each bench shaU be compacted prior to recdving fiU as specified herein for compacted natural ground. Ground slopes flatter than 20 percent shaU be benched when considered necessary by the Geotechnical Engineer. Any abandoned buried structures encountered during grading operations must be totaUy removed. AU underground utiUties to be abandoned beneath any proposed stmcture should be removed from within 10 feet of the stmcture and properly capped off. The resulting depressions from the above described procedure should be backfiUed with acceptable soil that is compacted to the requirements of the Geotechnical Engineer. Tliis includes, but is not Umited to, septic tanks, fuel tanks, sewer Unes or leach Unes, storm drains and water Unes. Any buried stmcmres or utiUties not to be abandoned should be brought to the attention of the Geotechnical Engineer so that he may determine if any spedal recommendation wiU be necessary. AU water weUs which wiU be abandoned should be backfiUed 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 CWE 2040602.1 June 29, 2004 AppendLx B, B-3 feet below the bottom of footing whichever is greater. The type of cap wiU depend on the diameter of the weU and should be determined by the Geotechnical Engineer and/or a quaUfied Stmcmral Engineer. FILL MATERIAL Materials to be placed in the fiU shaU be approved by the Geotechrucal Engineer and shaU be free of vegetable matter and other deleterious substances. Granular soil shaU contain sufficient fme material to fiU the voids. The definition and disposition of oversized rocks and expansive or detrimental sods are covered in the geotechnical report or Spedal Provisions. Expansive soils, soils of poor gradation, or soils with low strength characteristics may be thoroughly mixed with other soils to provide satisfactory fiU material, but oidy with the expUcit consent of the Geotechiucal Engineer. Any import material shaU be approved by the Geotechnical Engineer before bdng brought to the site. PLACING AND COMPACTION OF FILL Approved fiU material shaU be placed in areas prepared to receive fiU in layers not to exceed 6 inches in compacted thickness. Each layer shaU have a uniform moistore content in the range that wiU aUow the compaction effort to be effidentiy appUed to achieve the specified degree of compaction. Each layer shaU be uiuformly compacted to the specified minimum degree of compaction with equipment of adequate size to economicaUy compact the layer. Compaction equipment should dther be spedficaUy designed for soil compaction or of proven reUabiUty. The minimum degree of compaction to be achieved is specified in dther the Special Provisions or the recommendations contained in the preliminary geotechnical investigation report. When the stmctoral fiU material includes rocks, no rocks wiU be aUowed to nest and aU voids must be carefully fiUed with soil such that the minimum degree of compaction recommended in the Special Provisions is achieved. The maximum size and spacing of rock permitted in stmctural fills and in non- stmctoral fills is discussed in the geotechnical report, when appUcable. Field observation and compaction tests to estimate the degree of compaction of the fiU wiU be taken by the Geotechnical Engineer or his representative. The location and frequency of the tests shaU be at the Geotechnical Engineer's discretion. When the compaction test indicates that a particular layer is at less than die required degree of compaction, the layer shaU be reworked to the satisfaction of the Geotechrucal Engineer and untU the desired relative compaction has been obtained. CWE 2040602.1 June 29, 2004 Appendix B, B-4 Fill slopes shaU be compacted by means of sheepsfoot roUers or otiier suitable equipment Compaction by sheepsfoot roUer shaU be at vertical intervals of not greater than four feet In addition, fiU slopes at a ratio of two horizontal to one vertical or flatter, should be trackroUed. Steeper fiU slopes shaU be over-built and cut- back to finish contours after die slope has been constmcted. Slope compaction operations shaU result in aU fill material six or more inches inward from die finished face of the slope having a relative compaction of at least 90 percent of maximum dry densitj' or die degree of compaction spedfied in die Special Provisions section of this spedfication. The compaction operation on the slopes shaU be continued until the Geotechnical Engineer is of the opinion that the slopes wiU be surficiaUy stable. Density tests in the slopes wiU be made by die Geotechnical Engineer during constmction of the slopes to determine if the required compaction is being achieved. Where faiUng tests occur or otiier field problems arise, the Contractor wiU be notified that day of such conditions by written communication from the Geotechnical Engineer or liis representative in the form of a daily fidd report If the mediod of achieving the required slope compaction selected by die Contractor fails to produce the necessary results, the Contractor shaU rework or rebuild such slopes untU die required degree of compaction is obtained, at no cost to the Owner or Geotechnical Engineer. CUT SLOPES The Engineering Geologist shaU inspect cut slopes excavated in rock or Uthified formational material during the grading operations at intervals determined at his discretion. If any conditions not anticipated in the preUminary report such as perched water, seepage, lenticular or confined strata of a potentiaUy adverse natore, unfavorably mcUned bedding, joints or fault planes are encountered during grading, these conditions shaU be analped by die Engineering Geologist and Geotechnical Engineer to determine if mitigating measures are necessary. Unless otherwise spedfied in the geotechnical report, no cut slopes shaU be excavated higher or steeper than that aUowed by the ordinances of the controUing governmental agency. ENGINEERING OBSERVATION Field observation by the Geotechnical Engineer or his representative shaU be made during the filUng and compaction operations so that he can express his opinion regarding the conformance of the grading with acceptable standards of practice. Ndther the presence of the Geotechnical Engineer or his representative or I CWE 2040602.1 June 29, 2004 Appendix B, B-5 the observation and testing shaU release the Grading Contractor from his duty to compact aU fiU material to die spedfied degree of compaction. SEASON LIMITS Fill shaU not be placed during unfavorable weatiier conditions. When work is intermpted by heavy rain, filUng operations shaU not be resumed until the proper moisture content and density of the fiU materials can be achieved. Damaged site conditions resulting from weather or acts of God shaU be repaired before acceptance of work. RECOMMENDED GRADING SPECIFICATIONS - SPECIAL PROVISIONS RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted natoral ground, compacted fiU, and compacted backfUl shaU be at least 90 percent For street and parking lot subgrade, the upper six inches should be compacted to at least 95 percent relative compaction. EXPANSIVE SOILS: DetrimentaUy expansive sod is defined as dayey soil which has an expansion index of 50 or greater when tested in accordance with the Uniform BuUding Code Standard 29-2. OVERSIZED MATERIAL: Oversized fiU material is generaUy defined herein as rocks or lumps of soU over 6 inches in diameter. Oversized materials should not be placed in fiU unless recommendations of placement of such material is provided by the Geotechnical Engineer. At least 40 percent of the fiU soils shaU pass through a No. 4 U.S. Standard Sieve. TRANSITION LOTS: Where transitions between cut and fdl occur within the proposed budding pad, die cut portion should be undercut a minimum of one foot below the base of the proposed footings and recompacted as stmctoral backfiU. In certain cases that would be addressed in the geotechnical report, special footing reinforcement or a combination of special footing reinforcement and undercutting may be required.