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HomeMy WebLinkAbout6607-1; Proposed Residential Development El Camino; Proposed Residential Development El Camino; 2005-06-13Preliminary Geotechnical Investigation Proposed Residential Development El Camino Real Carlsbad, California (A.P.N. 167-080-35) June 13, 2005 Prepared For: MR. TED OLSON 4940 63rd Street San Diego, CA 92115 yj xo Prepared By: VINJE & MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue, Suite 102 ______ | Escondido, California 92029 ST Job #05-268-P VlNJE & MlDDLETQN ENGINEERING, INC Job #05-268-P June 10, 2005 2450 Vineyard Avenue Escondido. California 92029-1229 Phone (760) 743-1214 Fax (760) 739-0343 Mr. Ted Olson 4940 63rd Street San Diego, California 92115 PRELIMINARY GEOTECHNICAL INVESTIGATION, PROPOSED RESIDENTIAL DEVELOPMENT, EL CAMINO REAL, CARLSBAD, CALIFORNIA (A.P.N. 167-080-35) Pursuant to your request, Vinje and Middleton Engineering, Inc., has completed the enclosed Preliminary Geotechnical Investigation Report for the subject site. The following report summarizes the results of our field investigation, including laboratory analyses and conclusions, and provides recommendations for the proposed development as understood. From a geotechnical engineering standpoint, it is our opinion that the site is suitable for the planned single-family residential development and associated improvements provided the recommendations presented in this report are incorporated into the design and construction of the project. The conclusions and recommendations provided in this study are consistent with the site geotechnical conditions and are intended to aid in preparation of final development plans and allow more accurate estimates of development costs. If you have any questions or need clarification, please do not hesitate to contact this office. Reference to our Job #05-268-P will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. fjennis Middleton CEG #980 DM/jt PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED RESIDENTIAL DEVELOPMENT EL CAMINO REAL CARLSBAD, CALIFORNIA (A.P.N. 167-080-35) I. INTRODUCTION The property investigated in this work includes partially developed hillside terrain located on the west side of El Camino Real approximately 600 feet south of Chestnut Avenue in the City of Carlsbad. The property location is depicted on a Regional Index Map enclosed with this report as Plate 1. We understand that the site is planned for a single-family residential development with associated structures and improvements. Consequently, the purpose of this study was to determine soil and geotechnical conditions at the property and evaluate their influence upon the planned construction. Geologic mapping, test trench digging, soil sampling and testing were among the activities conducted in conjunction with this effort which has resulted in the geotechnical development and foundation recommendations presented herein. This office has also conducted previous geotechnical investigations adjacent to the subject property. The technical reports resulting from these investigations were reviewed in connection with this work. II. SITE DESCRIPTION Existing topographic conditions and a preliminary development scheme are shown on a Site Plan included with this report as Plate 2. The property is bordered by El Camino Real to the east, residential properties to the south and west, and undeveloped terrain to the north. Previous cut-fill grading at the site resulted in an existing nearly level pad area. The existing pad area extends south into adjacent property. The largest site slope ascends approximately 25 feet from the west margin of the existing graded pad. Slope gradients locally approach 114:1 (horizontal to vertical) at their steepest. Approximate limits of existing fills associated with the prior site grading are shown on Plate 2. Site drainage sheetflow in an easterly direction to El Camino Real. Some minor erosion was noted in the existing fills. Elsewhere, excessive scouring or erosion from uncontrolled run-off is not in evidence. III. PROPOSED DEVELOPMENT We understand the study property is planned for the support of a two-story dwelling with associated structures, pavings and underground utility improvements as conceptually shown on Plate 2. The planned development consists of a split-level building pad with a lower basement level. Building basement retaining walls are incorporated into the designs VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 2 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 to accommodate ground transitioning and achieve design grades. Minor to moderate cut- fill grading is planned for the creation of the level building and basement pads. Ground filling less than 5 feet high maximum and cut excavations on the order of 16 feet are anticipated. Detailed building plans are unavailable. However, it is anticipated that building construction will consist of lower masonry block basement walls, and upper wood-frame and stucco structures supported on shallow stiff continuous strip and spread pad concrete footings with slab-on-grade floor foundations. IV. SITE INVESTIGATION Subsurface conditions at the site were chiefly determined by the excavation of 5 exploratory test trenches dug with a tractor-mounted backhoe. All trenches were logged by our project geologist who also retained representative rock/soil samples at selected locations and frequent intervals for subsequent laboratory testing. Test trench locations are shown on Plate 2. A Geologic Cross-Section through the planned development is enclosed herein as Plate 3. Logs of the test trenches are enclosed with this report as Plates 4-6. Laboratory test results are summarized in a following section. V. GEOTECHNICAL CONDITIONS The study property is underlain by formational bedrock units mantled by a modest cover of fills and topsoil. Terrace Deposits are exposed in the slope along the western margin of the site. Instability is not indicated at the property. A. Earth Materials Terrace Deposits - Pleistocene age Terrace Deposits are exposed on an existing ascending slope along the west property margin. Exposures consist of dark- colored sandstone units that are typically fine to medium grained and massive. The sandstone was found in a cemented condition overall. Lower limits of the sandstone are marked by a cobble conglomerate lens that extends partially onto the existing pad. Minor erosion mark portions of the slope face. However, no evidence of shallow or deep-seated slope instability is indicated. An approximate attitude of the contact between the Terrace Deposit and underlying formational rock is favorable with a low-angle in-slope dip. Formational Bedrock - The proposed building pad and improvement areas are largely underlain by Eocene age sedimentary bedrock units typically designated Santiago Formation. At the project site, the formational rock units typically consist of light-colored clayey to silty sandstone. As exposed in our test trenches, site formational units are weathered friable near the surface becoming blocky and VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 3 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 cemented at depth. Project formational rocks are competent units that will adequately support the planned dwellings and improvements. Topsoil - A modest cover of topsoil mantles much of the Formational rock units at the study site. The topsoil typically consists of sandy to clay-rich deposits that were found in loose to soft conditions near the surface becoming medium dense to stiff at depth. Project topsoils thicken to the east and reach a maximum thickness of 11 feet as exposed in Test Trench 1-2. Fill - Artificial fills largely occupy the western portion of the subject site. Existing site fill deposits chiefly consist of silty sands which were likely generated during the prior on-site grading operations when the existing pad was created. Documentation for the fill placement is not available. Existing fills reached a maximum thickness of 13 feet at Test Trench T-3. Estimated limits of the existing fill deposits at the site are shown on Plate 2. Details of the underlying earth materials at the site are presented on the enclosed Test Trench Logs (Plates 4-6). Their subsurface relationship is depicted on the enclosed Plate 3. B. Groundwater and Surface Drainage Groundwater conditions were encountered in our test excavations in the easterly margin of the property. In Test Trench T-1 weeping water was encountered at a depth of 3 feet and likely reflects near surface perched water resulting from winter rainstorms. Groundwater was encountered in Test Trench T-2 at a depth of 8 feet at the formational rock contact. The noted subsurface water is not expected to significantly impact grading operations, however, some dewatering and drying of potentially wet soil should be anticipated. Like all graded building sites, the proper control of surface drainage is an important factor in the continued stability of the property. Irrigation and meteoric water should not be allowed to pond on lot surfaces and over-watering of site vegetation should be avoided. Project site and building basement retaining walls should be provided with adequate back drain systems. C. Slope Stability Landslides or other forms of geologic slope instability are not in evidence at the project site. The western site slope is performing well with no evidence of surficial or deep-seated instability. Cemented Terrace Deposits exposed on the slope face and underlying Formational rock materials are largely flat-lying to massive sandstone units which characteristically perform well with regard to gross stability and are expected to remain stable. VINJE & MIDDL.ETON ENGINEERING. INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION EL CAMINO REAL, CARLSBAD, CALIFORNIA PAGE 4 JUNE 13, 2005 D. Faults / Seismicity Faults or significant shear zones are not indicated on or near proximity to the project site. As with most areas of California, the San Diego region lies within a seismically active zone; however, coastal areas of the county are characterized by low levels of seismic activity relative to inland areas to the east. During a 40-year period (1934-1974), 37 earthquakes were recorded in San Diego coastal areas by the California Institute of Technology. None of the recorded events exceeded a Richter magnitude of 3.7, nor did any of the earthquakes generate more than modest ground shaking or significant damages. Most of the recorded events occurred along various offshore faults which characteristically generate modest earthquakes. Historically, the most significant earthquake events which affect local areas originate along well known, distant fault zones to the east and the Coronado Bank Fault to the west. Based upon available seismic data, compiled from California Earthquake Catalogs, the most significant historical event in the area of the study site occurred in 1800 at an estimated distance of 11.1 miles from the project area. This event, which is thought to have occurred along an off-shore fault, reached an estimated magnitude of 6.5 with estimated bedrock acceleration values of 0.120g at the project site. The following list represents the most significant faults which commonly impact the region. Estimated ground acceleration data compiled from Digitized California Faults (Computer Program EQFAULT VERSION 3.00 updated) typically associated with the fault is also tabulated: TABLE 1 FauttZone Rose Canyon Newport-lnglewood Coronado Bank Elsinore-Julian Distance from Bite 5.9 miles 6.3 miles 22.1 miles 23.2 miles Maximum Probable Acceleration (fUiji 0.224g 0.214g 0.178g 0.1 46g The location of significant faults and earthquake events relative to the study site are depicted on a Fault - Epicenter Map enclosed with this report as Plate 7. VlNJE & MlDDLETON ENGINEERING, INC. * 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 5 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 More recently, the number of seismic events which affect the region appears to have heightened somewhat. Nearly 40 earthquakes of magnitude 3.5 or higher have been recorded in coastal regions between January 1984 and August 1986. Most of the earthquakes are thought to have been generated along offshore faults. For the most part, the recorded events remain moderate shocks which typically resulted in low levels of ground shaking to local areas. A notable exception to this pattern was recorded on July 13, 1986. An earthquake of magnitude 5.3 shook County coastal areas with moderate to locally heavy ground shaking resulting in $700,000 in damages, one death, and injuries to 30 people. The quake occurred along an offshore fault located nearly 30 miles southwest of Oceanside. A series of notable events shook County areas with a (maximum) magnitude 7.4 shock in the early morning of June 28, 1992. These quakes originated along related segments of the San Andreas Fault approximately 90 miles to the north. Locally high levels of ground shaking over an extended period of time resulted; however, significant damages to local structures were not reported. The increase in earthquake frequency in the region remains a subject of speculation among geologists; however, based upon empirical information and the recorded seismic history of County areas, the 1986 and 1992 events are thought to represent the highest levels of ground shaking which can be expected at the study site as a result of seismic activity. In recent years, the Rose Canyon Fault has received added attention from geologists. The fault is a significant structural feature in metropolitan San Diego which includes a series of parallel breaks trending southward from La Jolla Cove through San Diego Bay toward the Mexican border. Test trenching along the fault in Rose Canyon indicated that at that location the fault was last active 6,000 to 9,000 years ago. More recent work suggests that segments of the fault are younger having been last active 1000 - 2000 years ago. Consequently, the fault has been classified as active and included within an Alquist-Priolo Special Studies Zone established by the State of California. Fault zones tabulated in the preceding table are considered most likely to impact the region of the study site during the lifetime of the project. The faults are periodically active and capable of generating moderate to locally high levels of ground shaking at the site. Ground separation as a result of seismic activity is not expected at the property. For design purposes, site specific seismic parameters were determined as part of this investigation in accordance with the California Building Code. The following parameters are consistent with the indicated project seismic environment and may be utilized for project design work: VlNJE & MlDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION EL CAMINO REAL, CARLSBAD, CALIFORNIA PAGE 6 JUNE 13, 2005 TABLE 2 Site Soil Profile Type So Seismic Zone 4 Seismic Zone Factor 0.4 Seismic Source Type B Seismic Response Coefficients Na 1.0 Nv 1.0 Ca 0.44 cv 0.65 Ts 0.593 To 0.119 According to Chapter 16, Division IV & V of the 2001 California Building Code. A site specific probabilistic estimation of peak ground acceleration was also performed using the FRISKSP (T. Blake, 2000) computer program. Based upon Boore et al (1997) attenuation relationship, a 10 percent probability of exceedance in 50 years was estimated to produce a site specific peak ground acceleration of 0.35g (Upper Limit Earthquake, ULE). The results were obtained from the corresponding Exceedance Probability (%) versus Acceleration (g) curve. E. Geologic Hazards Geologic hazards are not presently indicated at the project site. Exposed slopes do not indicate gross geologic instability. The most significant geologic hazards at the property will be those associated with ground shaking in the event of a major seismic event. Liquefaction or related ground rupture failures are not anticipated. F. Laboratory Testing / Results Earth deposits encountered in our exploratory test excavations were closely examined and sampled for laboratory testing. Based upon our test trench and field exposures site soils have been grouped into the following soil types: TABLE 3 Soil Type 1 2 3 4 Description brown to grey clayey sand to sandy clay (Fill/Topsoil) brown silty fine to medium sand (Fill/Topsoil/Alluvium) off-whit to grey clayey sand (Formational Rock) red-brown cobble conglomerate (Terrace Deposit) The following tests were conducted in support of this investigation: VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION EL CAMINO REAL, CARLSBAD, CALIFORNIA PAGE 7 JUNE 13, 2005 1. Maximum Dry Density and Optimum Moisture Content: The maximum dry density and optimum moisture content of Soil Types 1 and 2 were determined in accordance with ASTM D-1557. The test results are presented in Table 4. TABLE 4 Location T-2 @ 2' T-2 @ 41/2' Soif TytJe 2 1 Maximum Dry Density OVtef} 134.7 132.6 Optimum Moistere Content (tdopt-%} 7.0 8.9 2. Moisture-Density Tests (Undisturbed Chunk Samples): In-place dry density and moisture content of representative soil deposits beneath the site were determined from relatively undisturbed chunk samples using the water displacement test method. The tesults are presented in Table 5 and tabulated on the enclosed Test Trench Logs (Plates 4-6). TABLE 5 Sample Location T-1 @ 5' T-1 @ T T-1 @ 9' T-1 @11%' T-2 @ 2' T-2 @ 41/2' T-2 @ 8' T-2 @ 91/2' T-3 @ 91/2' T-3 @ 141/2' T-4 @ 41/2' SoH Type 1 1 1 3 2 1 1 3 2 3 3 field Moisture Content <u-%) 11.7 10.3 14.9 14.5 3.4 11.5 11.9 16.4 9.6 13.1 10.1 Field Dry Density {Yd-pef} 109.0 102.8 104.4 102.6 114.6 106.1 110.8 99.9 110.9 102.4 122.5 Max, Dry Density {Yin-pCf) 132.6 132.6 132.6 132.6 134.7 132.6 132.6 - 134.7 - - Ratra Of la-Place Dry Density To Max. Dry Density* (Ydffm * 100} 82.2 77.5 78.7 77.4 85.1 80.0 83.6 - 82.3 - - * Designated as relative compaction for structural fills. Required relative compaction for structural fill is 90% unless otherwise specified. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION EL CAMINO REAL, CARLSBAD, CALIFORNIA PAGE 8 JUNE 13, 2005 3. Expansion Index Test: Two expansion index tests were performed on representative samples of Soil Types 1 and 2 in accordance with the Uniform Building Code Standard 18-2. The test results are presented in Table 6. TABLE 6 Sample Location T-2 @ 2' T-2@ Soif Type 2 1 Remolded ut (%} 6.5 8.0 Saturation <%) 50.3 49.4 Saturated i to(%) 11.5 15.5 Expansion Index (El) 3 35 Expansion Potential very low low (w) = moisture content in percent. 4. Direct Shear Test: Two direct shear tests were performed on representative samples of Soil Types 2 and 3. The prepared specimens were soaked overnight, loaded with normal loads of 1, 2, and 4 kips per square foot respectively, and sheared to failure in an undrained condition. The test results are presented in Table 7. TABLE 7 Sample Location T-2 @ 2' T-4 @ 41/2' Soil Type 2 3 Sample \ Condition ; remolded to 90% of Ym @ % toopt remolded to 100% of in-place Wet Density (Yw-pcf) 129.7 ,_ 134.0 Angle of IntFrte. (3>-Oeg,) 30 32 Apparent Cohesion Ic-psfJ 121 85 5. Ph and Resistivity Test: Ph and resistivity of a representative sample of Soil Type 1 collected at selected locations was determined using "Method for Estimating the Service Life of Steel Culverts," in accordance with the California Test 643. The test result is presented in Table 8. TABLE 8 Sample Location T-1 @ 2' Sdil Type_ 1 Minimum: Resistivity (OHM-CM) _[ Ph 1008 6.55 6. Sulfate Test: One sulfate test was performed on a representative sample of Soil Type 1 in accordance with California Test 417. The test result is presented in Table 9. VlNIE & MlDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 * Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 9 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 TABLE 9 Sample Location T-1 @ 2' Soil Type 1 Amount of Water Soluble Sulfate (SO4) lrrSoilf% by Weight) 0.005 VI. CONCLUSIONS Based upon the foregoing investigation, development of the project site substantially as proposed, is feasible from a geotechnical viewpoint. The property is underlain by dense and stable formational bedrock units which are mantled by a thin to moderate section of loose to medium dense sandy to clayey fill / topsoils. Geotechnical factors presented below are unique to the project site and will influence grading procedures and associated development costs: * Site natural terrain and existing cut slope expose dense and competent terrace deposits/formational sandstone units which are geologically stable. Instability, landslides or other forms of adverse geologic conditions which could preclude site development are not indicated. * Relatively deep basement excavations up to 16 feet maximum are planned to achieve lower level pad grade elevations. Stability of temporary excavation embankments will be a geotechnical concern. Temporary construction slopes should be excavated as recommended in the following sections. Elsewhere, minor grade modifications are proposed overall to construct level building surfaces. Unusual excavation difficulties within the on-site bedrock units are not anticipated. * Site existing fills, topsoils, and upper weathered soft formational rock/terrace deposits are not suitable for support of the planned construction and improvements in their present condition. Removal and recompaction of these deposits to dense and competent formational rock units will be necessary in order to construct stable ground surfaces suitable for the support of the proposed structures and improvements. Added removals of cut ground will also be necessary in the case of cut-fill transition pads which expose formational rock units so that uniform bearing soil conditions are created throughout the building and improvement surfaces. * Earth materials generated from the site removals and excavations will include some clayey soils. Clayey soils should be selectively buried in deeper fills or thoroughly mixed with an abundant of very low expansive sandy soils available VlNJE & MlDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 10 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 from site excavations in order to manufacture a very low to low expansive mixture. Some overly wet to locally saturated soils should also be anticipated from the lower fill/topsoil removals near the formational rock contacts. Added processing and moisture conditioning efforts should also be anticipated for manufacturing a uniform mixture suitable for reuse as site compacted fills. Clayey soils should not be used for wall backfills. Based on the grading recommendations given herein, final bearing and subgrade soils may be expected to consist of gravelly silty to clayey sand deposits (SM/SC) with low expansion potential (expansion index less than 51). Actual classification and expansion characteristic of finished grade soil mix can only be provided in the final as-graded compaction report based on appropriate testing. Potentially expansive bearing soils (expansion index greater than 21) will require special geotechnical engineering mitigation design which typically may include pre- saturation of subgrade soils as well as deeper foundations and thicker slab-on- grade floors with heavier steel reinforcement. Foundation bearing soils at the final pad grades should be additionally tested at the completion of rough grading to confirm expansion characteristics of the bearing soils which wiii govern final foundations and slab design. Based on the current design schemes, major graded cut and fill slopes are not planned in connection of the project development as proposed. Stability of new graded slopes will not be factor in site development. Groundwater conditions are not expected to significantly impact grading activities. However, minor to local dewatering efforts may be necessary based on seasonal conditions and may be anticipated. Construction during the dry summer months will reduce potential impacts of groundwater intrusions. Adequate site surface and subsurface drainage control remains a critical factor in the future stability of the developed property as planned. Surface drainage should be well developed and adequate back drains should be provided behind the planned site and building basement retaining walls as recommended in the following sections. Soil collapse, liquefaction and seismically induced settlements will not be a factor in the development of the project site. Post construction settlements will not be a factor in construction of the planned new structures provided our remedial grading and foundation recommendations are followed. VINJE & MIDDLI.TON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 11 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 VII. RECOMMENDATIONS The following recommendations are provided based on the planned construction scheme as conceptually shown on the enclosed Plate 2. Added or modified recommendations may also be appropriate and can be provided at the final plan review phase when detailed construction plans are finalized: A. Remedial Grading and Earthworks Cut-fill and remedial grading techniques should be used in order to achieve final design grades and construct safe and stable surfaces beneath the new structures and improvements. All grading and project construction should be completed in accordance with the Appendix Chapter 33 of the California Building Code, City of Carlsbad Grading Ordinances, the Standard Specifications for Public Works Construction, and the requirements of the following sections: 1. Clearing and Grubbing: Existing vegetation, deleterious materials and debris should be removed from areas to receive new fills, structures, and improvements plus 10 feet where possible, and as directed in the field. Prepared ground should be inspected and approved by the project geotechnical engineer or his designated field representative prior to the remedial grading work. Existing underground utilities in the construction areas should be pot-holed, identified and marked prior to the actual work. Inactive lines should be properly removed or abandoned as approved. Abandoned underground structures, tanks and pipes should also be removed and the generated voids properly backfilled with compacted soils in accordance with the recommendations of this report. 2. Removals and Over-excavations: Existing site loose to soft fills, topsoils, and upper weathered soft formational rock units at the project site should be removed to the underlying competent formational units or firm native ground as approved in the field by the project geotechnical engineer, and placed back as properly compacted fill. Typical removal depths in the vicinity of individual exploratory test sites are shown in Table 10. Locally deeper removals may also be necessary based on the actual field exposures and should be anticipated: VlNJE & MlDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 * Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION EL CAMINO REAL, CARLSBAD, CALIFORNIA PAGE 12 JUNE 13, 2005 TABLE 10 Location T-1 T-2 T-3 T-4 T-5 Totel Depth^ m 12' 10' 14' 5' 41/2' *,«•» % not encountered not encountered not encountered Estimated Removal Depths M 3' (minimum) 9' 13' 4' r Comments Driveway areas. Trench sloughing from 2!4' to 4'. May require stabilization geogrid or extend removals 1 1 feet to formational rock units. May require local dewatering. Lower pad areas. Remove entire section of existing fills and topsoil. May require local dewatering. Building pad areas. Trench caving and sloughing to 13'. Remove the entire section of existing fills. Upper pad areas. Remove the entire section of existing fills. Upper building areas. Depth of transition undercut may govern. Explanations: 1. In the cut areas, depths of cut and/or undercut may govern removals and over-excavation depths. 2. All depths are measured from the existing ground levels. 3. Actual depths may vary at the time of construction based on actual subsurface exposures. 4. Firm native ground is defined as undisturbed natural ground with in-place densities of Q7% or greater. Ground stabilization geogrid or extending removals to formational units will be required in the event firm ground is not exposed at the bottom over-excavations underneath the planned on-grade driveway and improvement areas. 5. Bottom of all removals should be additionally prepared and recompacted as directed in the field. 6. Exploratory trenches excavated in connection with our study at the indicated locations were backfilled with loose and uncompacted deposits. The loose/uncompacted backfill soils within these trenches shall also be re-excavated and placed back as properly compacted fills as a part of the project grading operations. 7. All grounds steeper than 5:1 receiving fills/backfills should be properly benched and keyed as directed in the field. 3. Bearing Soils Transitioning: Project building/wall foundations should be uniformly supported on compacted fill soils. Foundation transitioning from compacted fills to cut ground or undisturbed formational units should not be allowed. The cut or undisturbed natural ground portions of the bearing soils in the transition pads should be undercut a minimum of 3 feet below rough finish grades or 12 inches below the bottom of the deepest footing(s), whichever is more, and placed back as properly compacted fills. There should also be at least 12 inches of compacted subgrade soils below all on-site pavings as well as surface and underground improvements. VlNJE & MlDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 13 EL CAMINO REAL, CARLSBAD. CALIFORNIA JUNE 13, 2005 4. Dewatering: Significant amounts of groundwater intrusions requiring an ambitious dewatering is currently not indicated. However, minor to locally moderate seeps may be anticipated during site removals and excavations particularly near the lower contacts with formational units. Consequently, some dewatering using a sump pump may be required to remove the seeping water and allow over-excavations and subsequent fill placement. For this purpose, a sump should be excavated at a low point in the excavation and provided with a pump which can effectively remove the intruding water. Asubdrain system consisting of a 4-inch perforated pipe (SDR 35) surrounded in %-inch crushed rocks and wrapped in filter fabric may also be required at the bottom of the over-excavations based on actual site conditions at the time of earthworks constructions as directed in the field and should be anticipated. Specific recommendations should be given at that time if it becomes necessary. Grading and construction during the dry summer months should be considered. 5. Temporary Construction Slopes: Existing upper fills/topsoils at the site are loose to very loose deposits which will likely experience caving and sloughing in larger unsupported temporary vertical slopes. Safe and stable construction slopes should be developed during the removals/over-excavations and erection of lower basement wall. Temporary excavation slopes may be constructed at near vertical gradients to a maximum of 3 feet. Construction slopes greater than 3 feet and less than 12 feet high maximum may be constructed near vertical gradients in lower 3 feet and laid back at %:1 gradient within the upper sections. Temporary construction slopes greater than 12 feet and less than 20 feet high maximum may be constructed at near vertical gradients in lower 3 feet, laid back at YzA gradient from 3 to 10 feet and 1:1 gradients within the upper sections. The remaining wedge of soil should be properly benched and tightly keyed-in as the backfilling progresses. Shoring and trench shield support will be required for vertical excavations greater than 3 feet maximum unless otherwise approved in the field by the project geotechnical consultant. The project contractor shall obtain appropriate permits, as necessary and conform to the requirements of Cal-OSHA and respective governing agencies as required and appropriate. Additional specific recommendations including flatter construction slopes and the need for temporary shoring should be given by the project geotechnical consultant at the time of earthwork operations based on actual field exposures and should be anticipated. VlNJE & MiDOLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 14 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 6. Fill Materials, Select Grading and Compaction: Soils generated from the removals of the existing fills and topsoils are considered suitable for reuse as new compacted site fills provided all trash, debris and unsuitable materials are selectively removed and properly disposed of to the satisfaction of the project geotechnical engineer. The removals of on-site surficial soils, however, will generate some clayey to rocky soils. Clayey site soils, where encountered, should be selectively buried in deeper fills a minimum of 3 feet below rough finish grades or may be thoroughly mixed with an abundance of very low expansive sandy soils available from site excavations in order to manufacture a low to very low expansive mixture as directed in the field. Clayey soils and larger cobble sizes should not be used in wall backfills. Some wet to locally saturated soils should also be expected from the lower removals impacted by groundwater seeps requiring spreading and drying efforts. Added processing, mixing and moisture conditioning efforts should be expected for manufacturing a uniform mixture for use in site fills and backfills. Project fills shall be clean deposits consisting of minus 6-inch particles and include at least 40% finer than #4 sieve materials by weight. Wall backfills shall consist of minus 3 inches particles. Uniform bearing soil conditions should be constructed at the site by the grading operations. Site soils should be adequately processed, thoroughly mixed, moisture conditioned to slightly (2%- 3%) above the optimum moisture levels as directed in the field, manufactured into a uniform mixture, placed in thin uniform horizontal lifts and mechanically compacted to a minimum 90% of the corresponding laboratory maximum dry density per ASTM D-1557, unless otherwise specified. A minimum of 90% compaction levels will be required for all structural fills and wall/trench backfills. In the improvement areas, fills should also be compacted to a minimum 90% with the exception of the upper 12 inches under the asphalt paving surfaces where a minimum of 95% compaction levels will be required. 7. Shrinkage and Import Soils: Based upon our analyzes, on-site existing fills and topsoil deposits may be expected to shrink approximately 10% to 20% on a volume basis when compacted to at least 90% of the corresponding maximum density. Import soils, if required to complete grading or wall backfilling, should be very low expansive granular sandy deposits (100% passing %-inch sieve, more than 50% passing sieve #4 sieve and less than 20% passing sieve #200 with expansion index less than 21) inspected and approved by the project geotechnical consultant prior to delivery to the site. VINJE & MlDDLHTON ENGINEERING, INC. • 2450 Vinevard Avenue • Escondido, California 92029-1229 • Phone ( 760} 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 15 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 8. Wall Back Drainage System: All site retaining and building basement walls should be provided with an adequate back drainage system. The wall back drain system should consist of a minimum 18 inches wide trench excavated to the depths of the wall foundation level. The drain trench should be provided with a minimum 4-inch diameter, Schedule 40 (SDR 35) perforated pipe surrounded with a minimum of 2.25 cubic feet per foot of %-crushed rocks wrapped in filter fabric (Mirafi 140 N), or Caltrans Class 2 permeable aggregate. The perforated drain pipe should be installed at suitable elevations to allow for adequate fall via non-perforated solid pipe (Schedule 40 or SDR 35) to an approved outlet. Filter fabric can be eliminated if Class 2 permeable material is used. Typical wall back drain system is depicted on the enclosed Plate 8. Appropriate waterproofing should be provided behind the walls. Protect pipe outlet as necessary. 9. Drainage and Erosion Control: A critical element to the continued stability of the graded building pads is an adequate surface drainage system. This can most effectively be achieved by installation of appropriate surface drainage facilities. Building pad surface run-off should be collected and directed away from the planned buildings and improvements to a selected location in a controlled manner. Drainage swales should be provided at the top and toe of the slopes per project grading/drainage improvement plans. Area drains should be installed. Temporary erosion control facilities and silt fences should be installed during the construction phase periods and until landscaping is established as indicated and specified on the approved project erosion plans. 10. Engineering Inspections: All grading operations including removals, suitability of earth deposits used as compacted fills, and compaction procedures should be continuously inspected and tested by the project geotechnical consultant and presented in the final as-graded compaction report. The nature of finished subgrade soils should also be confirmed in the final compaction report at the completion of remedial grading. Geotechnical engineering inspections shall include but not limited to the following: * Initial Inspection - After the grading / brushing limits have been staked but before grading / brushing starts. * Bottom of over-excavation inspection - After the natural ground or bedrock is exposed and prepared to receive fill but before fill is placed. VINIE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 16 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 Excavation inspection - After the excavation is started but before the vertical depth of excavation is more than 5 feet. Local and Cal-OSHA safety requirements for open excavations apply. Fill / backfill inspection - After the fill / backfill placement is started but before the vertical height of fill / backfill exceeds 2 feet. A minimum of one test shall be required for each 100 lineal feet maximum in every 2 feet vertical gain with the exception of wall backfills where a minimum of one test shall be required for each 25 lineal feet maximum. Wall backfills shall also be mechanically compacted to at least 90% compaction levels unless otherwise specified. Finish rough and final pad grade tests shall be required regardless of fill thickness. Foundation trench inspection - After the foundation trench excavations but before steel placement. Foundation bearing / slab subgrade soils inspection - Prior to the placement of concrete for proper moisture and specified compaction levels. Foundation / slab steel inspection - After steel placement is completed but before the scheduled concrete pour. Subdrain / wall back drain inspection - After the trench excavations but during the actual placement. All material shall conform to the project material specifications and approved by the project soils engineer. Underground utility / plumbing trench inspection - After the trench excavations but before placement of bedding or installation of the underground facilities. Local and Cal-OSHA safety requirements for open excavations apply. Inspection of pipe bedding may also be required by the project geotechnical engineer. Underground utility / plumbing trench backfill inspection - After the backfill placement is started above the pipe zone but before the vertical height of backfill exceeds 2 feet. Testing of the backfill within the pipe zone may also be required by the governing agencies. Pipe bedding and backfill materials shall conform to the governing agencies' requirements and project soils report if applicable. All trench backfills shall be mechanically compacted to a minimum of 90% compaction levels unless otherwise specified. Plumbing trenches over 12 inches deep maximum under the interior floor slabs should also be mechanically compacted and tested for a minimum of 90% compaction levels. Flooding or jetting techniques as a means of compaction method shall not be allowed. VINJE & MlDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 17 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 * Pavement/improvements subgrade and basegrade inspections - Prior to the placement of concrete or asphalt for proper moisture and specified compaction levels. B. Foundations and Slab-on-Grade Floors The following recommendations are consistent with low expansive (expansion index less than 51) gravelly silty to clayey sand (SM/SC) foundation bearing soils and site specific geotechnical conditions. Additional recommendations may also be required and should be given at the plan review phase. All design recommendations should also be further confirmed and/or revised at the completion of rough grading based on the expansion characteristics of the foundation bearing soils and as-graded site geotechnical conditions, and presented in the final as-graded compaction report: 1. Continuous strip wall foundations should be sized at least 15 inches wide and 18 inches deep for single-story and two-story structures. Spread pad footings should be at least 24 inches square and 12 inches deep. Footing depths are measured from the lowest adjacent ground surface, not including the sand/gravel layer beneath floor slabs. Exterior continuous footings should enclose the entire building perimeter. 2. Continuous interior and exterior foundations should be reinforced with a minimum of four #4 reinforcing bars. Place 2^4 bars 3 inches above the bottom of the footing and 2-#4 bars 3 inches below the top of the footing. Reinforcement details for isolated pad footings should be provided by the project architect / structural engineer. 3. All interior slabs should be a minimum of 4 inches in thickness, reinforced with #3 reinforcing bars spaced 16 inches on center each way, placed mid-height in the slab. Slabs should be underlain by 4 inches of clean sand (SE 30 or greater) which is provided with a well performing moisture barrier/vapor retardant (minimum 10-mil plastic) placed mid-height in the sand. 4. Provide "softcut" contraction / control joints consisting of sawcuts spaced 10 feet on center maximum each way. Cut as soon as the slab will support the weight of the saw and operate without disturbing the final finish which is normally within 2 hours after final finish at each control joint location or 150 psi to 800 psi. The softcuts should be a minimum of 1-inch in depth but not to exceed 1%-inches deep maximum. Anti-ravel skid plates should be used and replaced with each blade to avoid spalling and raveling. Avoid wheeled equipment across cuts for at least 24 hours. ViNME & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 18 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 5. Provide re-entrant corner reinforcement for all interior slabs. Re-entrant corners will depend on slab geometry and/or interior column locations. The enclosed Plate 9 may be used as a general guideline. 6. Foundation bearing and slab subgrade soils should not be allowed to dry below the as-graded moisture contents prior to pouring the concrete or additional ground preparations and moisture conditioning will be required as directed in the field. 7. Foundation trenches and slab subgrade soils should be inspected and tested for proper moisture and specified compaction levels and approved by the project geotechnical consultant prior to the placement of concrete. C. Exterior Concrete Slabs / Flatworks 1. All exterior slabs (walkways, and patios) should be a minimum 4 inches in thickness reinforced with 6x6/10x10 welded wire mesh carefully placed mid- height in the slab. 2. Provide "tool joint" or "softcut" contraction/control joints spaced 10 feet on center (not to exceed 12 feet maximum) each way. Tool or cut as soon as the slab will support weight and can be operated without disturbing the final finish which is normally within 2 hours after final finish at each control joint location or 150 psi to 800 psi. Tool or softcuts should be a minimum of 1-inch but should not exceed 1%-inches deep maximum. In case of softcut joints, anti-ravel skid plates should be used and replaced with each blade to avoid spalling and raveling. Avoid wheeled equipments across cuts for at least 24 hours. 3. All exterior slab designs should be confirmed in the final as-graded compaction report. 4. Subgrade soils should be tested for proper moisture and specified compaction levels and approved by the project geotechnical consultant prior to the placement of concrete. D. Soil Design Parameters The following soil design parameters are based upon tested representative samples of on-site earth deposits. All parameters should be re-evaluated when the characteristics of the final as-graded soils have been specifically determined: VlNJE & MlDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 19 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 * Design wet density of soil = 130 pcf. * Design angle of internal friction of soil = 30 degrees. * Design static active soil pressure for retaining structures = 43 pcf (EFP), level backfill, cantilever, unrestrained walls. * Design seismic active soil pressure for retaining walls = 32 pcf (EFP), level backfill, cantilever, unrestrained walls (see note below). * Design static at-rest soil pressure for retaining structures = 65 pcf (EFP), non- yielding, restrained walls. * Design seismic at-rest soil pressure for retaining structures = 53 pcf (EFP), non- yielding, restrained walls (see note below). * Design passive soil resistance for retaining structures = 389 pcf (EFP), level surface at the toe. * Design coefficient of friction for concrete on soils = 0.36. * Net allowable foundation pressure (minimum 15 inches wide by 18 inches deep footings) = 2000 psf. * Allowable lateral bearing pressure (all structures except retaining walls) for certified on-site soils = 150 psf/ft. Notes: * Use a minimum safety factor of 1.5 for wall over-turning and sliding stability. However, because large movements must take place before maximum passive resistance can be developed, a minimum safety factor of 2 may be considered for sliding stability particularly where sensitive structures and improvements are planned near or on top of retaining walls. * Retaining walls higher than 12 feet in maximum height shall be designed to resist an additional earth pressure caused by seismic ground shaking as provided herein. The indicated design seismic active soil pressures were determined based on the Mononobe-Okabe solution and 65% of the design peak ground acceleration (PGA = 0.35g) and assumptions made herein, and should be considered acting at 1/3-height below the top of the wall. The seismic active soil pressures shall be considered in addition to the design static active and at-rest soil pressures for both unrestrained yielding and restrained non-yielding walls. * When combining passive pressure and frictional resistance the passive component should be reduced by one-third. * The indicated net allowable foundation pressures provided herein were determined based on a minimum 15 inches wide by 18 inches deep footings and may be increased by 20% for each additional foot of depth and 15% for VlNJE & MlDDLETON ENGINEERING. INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 20 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 each additional foot of width to a maximum of 4500 psf. The allowable foundation pressures provided herein also apply to dead plus live loads and may be increased by one-third for wind and seismic loading. * The lateral bearing earth pressures may be increased by the amount of designated value for each additional foot of depth to a maximum of 1500 pounds per square foot. E. Asphalt and PCC Pavement Design Specific pavement designs can best be provided at the completion of rough grading based on R-value tests of the actual finish subgrade soils. The following structural sections, however, may be considered for initial planning phase cost estimating purposes only (not for construction): 1. A minimum section of 3 inches asphalt on 6 inches Caltrans Class 2 aggregate base or the minimum structural section required by the City of Carlsbad, whichever is more, may be considered for the on-site asphalt paving surfaces outside the public and private right-of-way. Actual designs win depend on the final R-value, design Tl and approval of the City of Carlsbad. Base materials should be compacted to a minimum 95% of the corresponding maximum dry density (ASTM D-1557). Subgrade soils beneath the asphalt paving surfaces should also be compacted to a minimum 95% of the corresponding maximum dry density within the upper 12 inches. 2. Residential PCC driveways and parking supported on low expansive (expansion index less than 51) subgrade soils should be a minimum of 5V2 inches in thickness, reinforced with #3 reinforcing bars at 18 inches on center each way placed 2 inches below the top of slab. Subgrade soils beneath the PCC driveways and parking should be compacted to a minimum 90% of the corresponding maximum dry density within the upper 6 inches. Provide "tool joint" or "softcut" contraction / control joints spaced 10 feet on center (not to exceed 15 feet maximum) each way. Tool or cut as soon as the slab will support weight and can be operated without disturbing the final finish which is normally within 2 hours after final finish at each control joint location or 150 psi to 800 psi. Tool or softcuts should be a minimum of 1-inch but should not exceed 1% inches deep maximum. In case of softcut joints, anti-ravel skid plates should be used and replaced with each blade to avoid spalling and raveling. Avoid wheeled equipments across cuts for at least 24 hours. VINJE & MJODLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760') 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 21 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 3. Base and basegrade should be tested for proper moisture and specified compaction levels and approved by the project geotechnical consultant prior to the placement of the base or asphalt / PCC finish surface. 4. Base section and subgrade preparations per structural section design, will be required for all surfaces subject to traffic including roadways, travelways, drive lanes, driveway approaches and ribbon (cross) gutters. Driveway approaches within the public right-of-way should have 12 inches subgrade compacted to a • minimum of 95% compaction levels, and provided with a 95% compacted Class 2 base section per the structural section design. Provide 6 inches of Class 2 base under curb and gutters and 4 inches of Class 2 base (or 6 inches of Class III) under sidewalks. Base layer under curb and gutters should be compacted to a minimum of 95%, while subgrade soils under curb and gutters, and base and subgrade under sidewalks should be compacted to a minimum of 90% compaction levels. Base section may not be required under curb and gutters, and sidewalks in the case of very low expansive subgrade soils (expansion index less than 21). Appropriate recommendations should be given in the final as-graded compaction report. F. General Recommendations 1. The minimum foundation design and steel reinforcement provided herein is based on soil characteristics only and is not intended to be in lieu of reinforcement necessary for structural consideration. All recommendations should be evaluated and confirmed by the project architect / structural engineer. 2. Adequate staking and grading control is a critical factor in properly completing the recommended remedial and site grading operations. Grading control and staking should be provided by the project grading contractor, or surveyor/civil engineer, and is beyond the geotechnical engineering services. Inadequate staking and/or lack of grading control may result in unnecessary additional grading which will increase construction costs. 3. Expansive clayey soils should not be used for backfilling of any retaining structure. All retaining walls should be provided with a 1:1 wedge of granular, compacted backfill measured from the base of the wall footing to the finished surface. 4. All underground utility and plumbing trenches should be mechanically compacted to a minimum 90% of the maximum dry density of the soil unless otherwise specified. Care should be taken not to crush the utilities or pipes VtNjE & MlDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 22 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 during the compaction of the soil. Non-expansive, granular backfill soils should be used. 5. Based upon the results of the tested soil sample, the amount of water soluble sulfate (S04) in the soil was found to be 0.005 percent by weight which is considered negligible according to California Building Code Table No. 19-A-4. Portland cement Type II may be used. 6. Potentially expansive clayey deposits are subject to continued swelling and shrinkage upon wetting and drying. At the site, maintaining a uniform as-graded soil moisture during the post construction periods is essential in the future performance of the site structures and improvements. In no case should water be allowed to pond or accumulate adjacent to the improvements and structures. 7. Site drainage over the finished pad surface should flow away from structures onto the street in a positive manner. Care should be taken during the construction, improvements, and fine grading phases, not to disrupt the designed drainage patterns. Rooflines of the buildings should be provided with roof gutters. Roof water should be collected and directed away from the buildings and structures to a suitable location. Consideration should be given to adequately damp-proof/waterproof the basement walls / foundations and provide the planter areas adjacent to the foundations with an impermeable liner and a subdrainage system. 8. Final plans should reflect preliminary recommendations given in this report. Final foundations and grading plans may be reviewed by the project geotechnical consultant for conformance with the requirements of the geotechnical investigation report outlined herein. More specific recommendations may also be necessary and should be given when final grading and architectural/structural drawings are available. 9. All foundation trenches should be inspected to ensure adequate footing embedment and confirm competent bearing soils. Foundation and slab reinforcements should also be inspected and approved by the project geotechnical consultant. 10. The amount of shrinkage and related cracks that occur in the concrete slab-on- grades, flatworks and driveways depends on many factors, the most important of which is the amount of water in a concrete mix. The purpose of the slab reinforcement is to keep normal concrete shrinkage cracks closed tightly. The amount of concrete shrinkage can be minimized by reducing the amount of water in the mix. To keep shrinkage to a minimum the following should be considered: VlNJE & MlDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760") 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 23 EL CAMINO REAL, CARLSBAD, CALIFORNIA JUNE 13, 2005 * Use the stiffest mix that can be handled and consolidated satisfactorily. * Use the largest maximum size of aggregate that is practical, (for example, concrete made with 3/s-inch maximum size aggregate usually requires about 40 Ibs more (nearly 5 gal.) water per cubic yard than concrete with 1-inch aggregate). * Cure the concrete as long as practical. The amount of slab reinforcement provided for conventional slab-on-grade construction considers that good quality concrete materials, proportioning, craftsmanship, and control tests where appropriate and applicable, are provided. 11. A preconstruction meeting between representatives of this office, the property owner or planner, the grading contractor / builder, and the city inspector is recommended in order to discuss grading/construction details associated with site development. VIII. LIMITATIONS The conclusions and recommendations provided herein have been based on available data obtained from the review of pertinent reports and plans, subsurface exploratory excavations as well as our experience with the soils and formational materials located in the general area. The materials encountered on the project site and utilized in our laboratory testing are believed representative of the total area; however, earth materials may vary in characteristics between excavations. Of necessity we must assume a certain degree of continuity between exploratory excavations and/or natural exposures. It is necessary, therefore, that all observations, conclusions, and recommendations be verified during the grading operation. In the event discrepancies are noted, we should be contacted immediately so that an inspection can be made and additional recommendations issued if required. The recommendations made in this report are applicable to the site at the time this report was prepared. It is the responsibility of the owner/developer to ensure that these recommendations are carried out in the field. It is almost impossible to predict with certainty the future performance of a property. The future behavior of the site is also dependent on numerous unpredictable variables, such as earthquakes, rainfall, and on-site drainage patterns. The firm of VINJE & MIDDLETON ENGINEERING, INC., shall not be held responsible for changes to the physical conditions of the property such as addition of fill soils, added cut slopes, or changing drainage patterns which occur without our inspection or control. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 PRELIMINARY GEOTECHNICAL INVESTIGATION EL CAMINO REAL, CARLSBAD, CALIFORNIA PAGE 24 JUNE 13, 2005 The property owner(s) should be aware that the development of cracks in all concrete surfaces such as floor slabs and exterior stucco are associated with normal concrete shrinkage during the curing process. These features depend chiefly upon the condition of concrete and weather conditions at the time of construction and do not reflect detrimental ground movement. Hairline stucco cracks will often develop at window/door corners, and floor surface cracks up to Vs-inch wide in 20 feet may develop as a result of normal concrete shrinkage (according to the American Concrete Institute). This report should be considered valid for a period of one year and is subject to review by our firm following that time. If significant modifications are made to your tentative development plan, especially with respect to the height and location of cut and fill slopes, this report must be presented to us for review and possible revision. Vinje & Middleton Engineering, Inc., warrants that this report has been prepared within the limits prescribed by our client with the usual thoroughness and competence of the engineering profession. No other warranty or representation, either expressed or implied, is included or intended. Once again, should any questions arise concerning this report, please do not hesitate to contact this office. Reference to our Job #05-268-P will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. Dennis Middleton CEG #980 ehdi S. Shariat 6174 Steven PG #6953 DM/SMSS/SJM/jt Distribution: Addressee (4) Private Eyes Engineers, Attn: Mr. Masood Gaskari (1) c:/jt/myfiles/prelims.05/05-268-P VINIE & MIDDLETON ENGINEERING, INC. • 2450 Vineyard Avenue • Escondido, California 92029-1229 • Phone (760) 743-1214 © 2OO2 D»l_orme. Topo USA ®. Data copyright of content owner www.delorrne.com PRIMARY DIVISIONS GROUP SYMBOL SECONDARY DIVISIONS OC O 5 £°co 5 o Q LL Z LU s £i£2 *E £ O I a; Qj UJ Z LU w 5 i 5 O Uj"rr wO GRAVELS MORE THAN HALF OF COARSE FRACTION IS LARGER THAN NO. 4 SIEVE SANDS MORE THAN HALF OF COARSE FRACTION IS SMALLER THAN NO. 4 SIEVE CLEAN GRAVELS (LESS THAN 5% FINES) GW Well graded gravels, gravel-sand mixtures, little or no fines. GP Poorly graded gravels or gravel-sand mixtures, little or no fines. GRAVEL WITH FINES GM Silty gravels, gravel-sand-silt mixtures, non-plastic fines. GC Clayey gravels, gravel-sand-clay mixtures, plastic fines. CLEAN SANDS (LESS THAN 5% FINES) sw Well graded sands, gravelly sands, little or no fines. SP Poorly graded sands or gravelly sands, little or no fines. SANDS WITH FINES SM Silty sands, sand-silt mixtures, non-plastic fines. SC Clayey sands, sand-clay mixtures, plastic fines. OCO Q Z 1 UJu_ rr y^ uj co i co co z co o< — o T -1 CM SILTS AND CLAYS LIQUID LIMIT IS LESS THAN 50% ML Inorganic silts and very fine sands, rock flour, silty or clayey fine sands or clayey silts with slight plasticity. CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays. OL Organic silts and organic silty clays of low plasticity. o £ o UJ C [^ Z SILTS AND CLAYS LIQUID LIMIT IS GREATER THAN 50% MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts. CH Inorganic clays of high plasticity, fat clays. OH Organic clays of medium to high plasticity, organic silts. HIGHLY ORGANIC SOILS PT Peat and other highly organic soils. GRAIN'SIZES u.s. STANDARD SERIES SIEVE 200 40 10 CLEAR SQUARE SIEVE OPENINGS 3/4" 3" 12" SILTS AND CLAYS SAND FINE MEDIUM COARSE GRAVEL FINE COARSE COBBLES BOULDERS RELATIVE DENSITY CONSISTENCY SANDS, GRAVELS AND NON-PLASTIC SILTS VERY LOOSE LOOSE MEDIUM DENSE DENSE VERY DENSE BLOWS/FOOT 0 - 4 4-10 10-30 30 - 50 OVER 50 CLAYS AND PLASTIC SILTS VERY SOFT SOFT FIRM STIFF VERY STIFF HARD STRENGTH 0- % % - % '/j - 1 1 - 2 2-4 OVER 4 BLOWS/FOOT 0 - 2 2 - 4 4 - 8 8 - 16 16-32 OVER 32 1. Blow count, 140 pound hammer falling 30 inches on 2 inch O.D. split spoon sampler (ASTM D-1586) 2. Unconfined compressive strength per SOILTEST pocket penetrometer CL-700 V _ ,_ _ . _ _, .. _ . I 24R = Standard Penetration Test (SPT) (ASTM D-1586)Sand Cone Test | Bulk Sample | 6 with blow counts per 6 inches j_J Chunk Sample O Driven Rings II 246 = California Sampler with blow counts per 6 inches VINJE & MIDDLETON ENGINEERING, INC. 2450 Vineyard Ave., #102 Escondido, CA 92029-1229 KEY TO EXPLORATORY BORING LOGS Unified Soil Classification System (ASTM D-2487) PROJECT NO KEY Date: 5-12-05 Logged by: SJM DEPTH (ft) - 0 - - - 5 - -10- -15- -20- SAMPLE • <7 ° \° Q rj 1 T-1 DESCRIPTION FILL: clayey sand to sandy clay. Brown to grey color. Moist. Soft to loose. ST-1 TOPSOIL: Silty medium sand. Dark brown color. Roots. Very moist to saturated. Loose to very loose. Odiferous. Weeping and sidewall sloughing. ST-2 Clayey sand. Red-brown color. Moist. Soft to firm. Scattered cobbles below 81/2'. ST-1 FORMATIONAL ROCK: Clayey sandstone. Medium to coarse grained. Off-white to grey with rust-colored staining. Weathered. Medium dense. Somewhat blocky to friable. Moderately cemented. End Test Trench at 12'. Weeping and sidewall sloughing from 21/2'-4'. uses SYMBOL SC/CL "/ sc sc FIELD MOISTURE (%) 11.7 10.3 14.9 14.5 FIELD DRY DENSITY (pcf) 109.0 102.8 104.4 102.6 RELATIVE COMPACTION (%) 82.2 77.5 78.7 . Date: 5-9-05 Logged by: SJM DEPTH (ft) - 0 - - 5 - -10 -15- SAMPLE JB _!• Q ,£./ n 1 VINJE & 245 Escc Office 7 T-2 DESCRIPTION FILUTOPSOIL: Silty fine to medium sand with cobbles. Brown color. Dry. Loose. Porous. Roots. ST-2 TOPSOIL: Clayey sand. Fine to medium grained. Red-brown color. Slightly moist. Somewhat blocky. Loose to very loose. Becomes very moist below 7'. ST-1 FORMATIONAL ROCK: Clayey sandstone to siltstone. Greyish color. Some rust- colored staining. Weathered. Moderately cemented. Somewhat blocky. Dense to stiff. Groundwater flowing into trench at contact. ST-3 End Test Trench at 10'. No caving. Groundwater at 9'. uses SYMBOL SM SC \ SC/ML I FIELD MOISTURE (%) 3.4 11.5 11.9 16.4 FIELD DRY DENSITY (pcf) 114.6 106.1 110.8 99.9 RELATIVE COMPACTION (%) 85.1 80.0 83.6 MIDDLETON ENGINEERING, INC TEST TRENCH LOGS D Vineyard Avenue, Suite 102 >ndido. California 92029-1229 EL CAMINO REAL ' CARLSBAD 60-743-1214 Fax 760-739-0343 PROJECT NO. 05-268-P PLATE 4 T Sand Cone Test • Bulk Sample Q Chunk Sample O Driven Rings Date: 5-12-05 Logged by: SJM DEPTH (ft) - 0 - - 5 - -10- -15- -20- SAMPLE \ Q Q T-3 DESCRIPTION FILL: Clayey sand with cobbles. Yellow-tan color. Slightly moist. Loose. ST-1 TOPSOIL: Silty fine sand. Red-brown color. Dry. Loose to very loose. Becomes slightly moist to moist at 8'. Scattered cobbles below 81/2'. ST-2 FORMATIONAL ROCK: Clayey sandstone. Medium to coarse grained. Off-white to grey color. Some rust-colored staining. Weathered. Somewhat blocky. Moderately cemented. ST-3 End Test Trench at 14'. Some sidewall sloughing to 13'. No groundwater uses SYMBOL SC SM SC FIELD MOISTURE (%) 9.6 13.1 FIELD DRY DENSITY (pcf) 110.9 102.4 RELATIVE COMPACTION (%) 82.3 - Date: 5-9-05 Logged by: SJM DEPTH (ft) - 0 - . 5 -10- -15- SAMPLE LI "^ \ VINJE & 245 Escc Office 7 T-4 DESCRIPTION FILL: Silty fine to medium sand with cobbles. Red-brown color. Dry. Loose. Fill placed atop sloping ground - no benching. ST-2 FORMATIONAL ROCK: Clayey sandstone. Medium to coarse grained. Off-white to yellow-tan color. Some rust-colored staining. Weathered. Somewhat blocky. Moderately well cemented. ST-3 End Test Trench at 5'. No caving. No Groundwater. uses SYMBOL SM / SC/SP / FIELD MOISTURE (%) 10.1 f FIELD DRY DENSITY (pcf) 122.5 RELATIVE COMPACTION (%) . MIDDLETON ENGINEERING, INC TEST TOEWCH L0GS mdidoycT^ EL CAMINO REAL - CARLSBAD 60-743-1214 Fax 760-739-0343 PROJECT NO. 05-268-P PLATE 5 T Sand Cone Test • Bulk Sample Q Chunk Sample O Driven Rings Date: 5-12-05 Logged by: SJM DEPTH (ft) - 0 - - _ - 5 - -10- -15- -20- SAMPLE \ \ | T-5 DESCRIPTION FILL: Silty fine sand. Brown color. Dry. Loose. ST-2 TERRACE DEPOSIT: Cobble conglomerate. Fine to medium sandy matrix. ±70% cobbles. Red-brown color. Moderately cemented. Difficult to excavate. Approximate attitude at lower , contact: N1 8° E, 9° NW. ST-4 FORMATIONAL ROCK: Clayey sandstone. Medium to coarse grained. Off-white to grey color. Some rust-colored staining. Moderately well cemented. Blocky. Dense. ST-3 End Test Trench at 41/2'. No caving. No groundwater uses SYMBOL SM I GM I SC / FIELD MOISTURE (%) , / FIELD DRY DENSITY (pcf) RELATIVE COMPACTION (%) Date: Logged by: DEPTH (ft) - 0 - - 5 - -10- -15- SAMPLE VINJE & 245I Escc Office 7 DESCRIPTION uses SYMBOL FIELD MOISTURE (%) FIELD DRY DENSITY (pcf) RELATIVE COMPACTION (%) MIDDLETON ENGINEERING, INC : TEST f^EliCH l^OGS J vineyard Avenue, suite iuz mdido. California 92029-1 229 EL CAMINO REAL ' CARLSBAD 60-743-1214 Fax 760-739-0343 PROJECT NO. 05-268-P PLATE 6 \ T Sand Cone Test • Bulk Sample Q Chunk Sample O Driven Rings 30 20 10 30 MILES FAULT - EPICENTER MAP SAN DIEGO COUNTY REGION INDICATED EARTHQUAKE EVENTS THROUGH 75 YEAR PERIOD (1900-1974) Map data is compiled from various sources including California Division of Mines and Geology, California Institude of Technology and the National Oceanic and Atmospheric Administration. Map is reproduced from California Division of Mines and Geology, "Earthquake Epicenter Map of California; Map Sheet 39." Earthquake Magnitude „ 4.0 TO 4.9 O 5.0 TO 5.9 CD 6.0 TO 6.9 3) 7.0 TO 7.9 ^ Fault. PROJECT: PLATE: Job #Q5-268-P EL CAMINO REAL. CARLSBAD RETAINING WALL DRAIN DETAIL Typical - no scale drainage *- Waterproofing Perforated drain pipe ^1 JS^ ' Granular, non-expansive ^ backfill. Compacted.-'/ •Filter Material. Crushed rock (wrapped in filter fabric) or Class 2 Permeable Material (see specifications below) footing - Competent, approved soils or bedrock CONSTRUCTION SPECIFICATIONS: SPECIFICATIONS f QRCALTKAtfSCLASS 2 PERMEABLE MATERIAL (68*1.025) U.S. STANDARD SIEVE SIZE % PASSING 1" 3/4 3/8 No, 4 Mo, 8 N0.3& NO, 59 No. 200 too. 90-100 4CMG0 25»4& 1S-33 5-15 0-7 0-3 Sarvd Equivalent > 75 1. Provide granular, non-expansive backfill soil in 1:1 gradient wedge behind wall. Compact backfill to minimum 90% of laboratory standard. 2. Provide back drainage for wall to prevent build-up of hydrostatic pressures. Use drainage openings along base of wall or back drain system as outlined below. 3. Backdrain should consist of 4" diameter PVC pipe (Schedule 40 or equivalent) with perforations down. Drain to suitable outlet at minimum 1%. Provide %" - 1V5" crushed gravel filter wrapped in filter fabric (Mirafi 140N or equivalent). Delete filter fabric wrap if Caltrans Class 2 permeable material is used. Compact Class 2 material to minimum 90% of laboratory standard. 4. Seal back of wall with waterproofing in accordance with architect's specifications. 5. Provide positive drainage to disallow ponding of water above wall. Lined drainage ditch to minimum 2% flow away from wall is recommended. * Use 1 % cubic foot per foot with granular backfill soil and 4 cubic foot per foot if expansive backfill soil is used. VINJE & MIDDLETON ENGINEERING, INC. PLATE 8 ISOLATION JOINTS AMD RE-ENTRANT CORNER REINFORCEMENT Typical - no scale CONTRACTION JOINTS RE-ENTRANT CORNER CRACK RE-ENTRANT CORNER—-* REINFORCEMENT NO. 4 BARS PLACED 1.5" BELOW TOP OF SLAB NOTES: 1. Isolation joints around the columns should be either circular as shown in (a) or diamond shaped as shown in (b). If no isolation joints are used around columns, or if the corners of the isolation joints do not meet the contraction joints, radial cracking as shown in (c)may occur (reference ACI). 2. In order to control cracking at the re-entrant corners (±270° corners), provide reinforcement as shown in (c). 3. Re-entrant corner reinforcement shown herein is provided as a general guideline only and is subject to verification and changes by the project architect and/or structural engineer based upon slab geometry, location, and other engineering and construction factors. VINJE & MIDDLETON ENGINEERING, INC. PLATE 9 £L ;AMIN° REAL 8 m iinoo inni © I: m OCD «Oon r>o