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HomeMy WebLinkAboutMS 04-09; BROWNE FAMILY; UPDATE GEOTECHNICAL REPORT, VACANT LOT AT SOUTH END OF DONNA COURT; 2004-06-30FTLAgr J\, \V~INJE & MIDDLETON ENGINEERING, JNC. 2450 Vineyard Avenue Job #99-384-P Escondido, California 920294229 June 30, 2004 Phone (760) 7434214 Fax (760) 739-0343 Mr. Patrick Jennings ' 3725 Westhaven Drive .. Carlsbad, California 92008 - UPDATE GEOTECHNICAL REPORT, VACANT LOT AT SOUTH END OF DONNA COURT (APN #205-260-05), CARLSBAD The above-referenced property was previously investigated by this office resulting in the following gèotechnical report . •, ' ,' . ':, •' .. " "Preliminary Geôtechnical Investigation, : Parcel 2, Southwest Terminus of Donna Court, Carlsbad, California", dated January 5, 2000 . .• A copy Of the referenced report is enclosed, with this letter as Appendix X. We understand your desire to proceed with site development substantially as outlined in the above-referenced report.' This notice 'will confirm that site. conditions reported in the referenced report remain the same and that conclusions and recomrnéndàtions contained therein remain valid and should be implemented during. site -development.* If you have any questions or need 'clarification, please do 'not hesitate to, contact this office. Reference to our Job #99-384-P will help to expedite our response to'your inquiries. We appreciate this' opportunity to be of service *to you. : VINJE & MIDDLETON ENGINEERING, INC (fi CEG98O\ (\S * ( CERTIFIED 1 *1R ' ENGINEERING / p •/i J/ DM/SMSSIt . . . OP Distribution. Addressee (2) Enclosure: Appendix A 'c:Ijt/myfiles/updates 04/99-354-0 update geo report hdi S. 'Shari #46174 1 No. 461,74' Exp. 12-31-06' Dennis Middleton CEG#980 APPENDIX A Preliminary Geotechnical Investigation Parcel 2, Southeast Terminus of Donha Court Carlsbad, California • (A.P.N. #205-260-05) January 5, 2000 Prepared For: FURMAN, JENNINGS & WOLFE Attention: Mr. Vincent Jennings 110 Highway 35 Middletown, New Jersey 07710 Prepared By: Vinje & Middleton Engineering, Inc. 2450 Vineyard Avenue, Suite 102 Escondido, California 92029 Job #99-384-P VINJE & MIDDLETON ENGINEERI VINTE & MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue Job #99-384-P Escondido, California 92029-1229 Phone (760) 743-1214 January 5, 2000 Fax (760) 739-0343 Furman, Jennings & Wolfe Attention: Mr. Vincent Jennings 110 Highway 35 Middletown, New Jersey 07710 PRELIMINARY GEOTECHNICAL INVESTIGATION, PARCEL 2, SOUTHEAST TERMINUS OF DONNA COURT, CARLSBAD, CALIFORNIA (A.P.N. #205-260-05) Pursuant to your, request, Vinje and Middleton Engineering, Inc., has completed the attached Preliminary Geotechnical Investigation Report for the above-referenced project 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 proposed residential development and the 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 #99-384-P will help expedite our response to your inquiries. We appreciate this opportunity to be of service to you. RMV:jt < — — • r- mmD0w> 0 mD0W> rn Cl) U Cl) 0 -' 0 • 0 Xø0: ': acs z 0 : - -I '• • ca 0 ' •0O D Z '<xin.. • -u 0 : -. )'<. .. • 33oaI) o • in2. 0 • ! rn 0 CL CD In 0 CL-: Co. T.2 CL CS 0 0• • z .... . • 5""a::: : : : : : oc 0 cn -I • • • . -I • • • —. • . • .. • c::: . • O R • • • • • • 01 . .. . • • .. • ::: : ::::.: • "O. • • . • • • •CD. • • . • • • .•.•. . .• • • • • 0 H.HH HHH HH • • . • • • I- '. • • • .. • • • un • . • • • S • z • . • ...••• • ... • - - - - - - CO 0) U. ."phC,3 K) Ui UI -bb C.) K) CO CO Cii ab K) K) K) K) - - - I-rn 0 -n C, 0 2 —I mi 2 —I Cl) TABLE OF CONTENTS (continued) PLATE NO. GeotechnicalIlflap ............ .......................... ............... i Test Trench Logs (with key) .....................2-3 Fault - EpicenterMap .................................................4 Isolation Joints and Re-Entrant Corner Réinforcemient .....................5 Retaining Wall Drain Detail ...............................................6 PRELIMINARY GEOTECHNICAL INVESTIGATION PARCEL 2, SOUTHEAST TERMINUS OF DONNA COURT CARLSBAD, CALIFORNIA (A.P.N. #205-260-05) INTRODUCTION The property investigated in this work is a small, undeveloped lot at the south terminus of Donna Court in Carlsbad. We understand that the site is proposed for the support of 'a single-family dwelling on 'a level surface created by minor cut/fill grading. Consequently, the purpose of this work was to determine geologic and soils conditions beneath the • property and their influence upon the planned development. Test hole digging, soil sampling and testing were among the activities conducted in connection with this work which have, resulted in construction recommendations presented herein. SITE DESCRIPTION The study site is depicted on a Geotechnical Map attached to this report as Plate 1. The property is a nearly level, triangUlar-shaped parcel which presently supports a light cover of grass and several small trees. Site drainage sheetfiows westward over the property. Excessive erosion resulting from concentrated runoff is not in evidence. Ill. PROPOSED DEVELOPMENT Preliminary plans for site development are depicted on Plate 1. As shown, minor cut/fill grading is planned for the creation of a level building surface. Small, 2:1 (horizontal to vertical) gradient slopes are proposed to maximum heights of 6 feet. An entrance driveway will provide access from the end of Donna Court. 0 ' Construction plans for the dwelling are presently unknown. However, it is anticipated that the new dwelling will be conventional wood-frame supported by continuous strip and spread pad foundations with slab-on-grade floors. A below ground basement room may be constructed beneath the residence. IV. SITE INVESTIGATION Geotechnical conditions at the project site were determined from the excavation of three test trenches dug with a tractor-mounted backhoe. The trenches were logged by our project geologist who also retained representative soil samples for laboratory testing. Trench locations are shown on Plate 1. Logs of the trenches-are attached as Plates 2 and 3. Laboratory test data are summarized in a following section. PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 2 PARCEL 2; DONNA COURT, CARLSBAD JANUARY 5, 2000 V. FINDINGS The study site is a nearly level parcel directly underlain by loose fill and topsoil deposits. More dense terrace deposit soils occur at depth beneath the upper soil cover. Earth Materials Surface areas of the project site are mantled by old fill and topsoil deposits which consist chiefly of finesilty sands. These are loose, unconsolidated deposits that extend to indicated depths of 2 to 5% feet below existing surface grades. Below the soil cover, natural terrace deposit materials predominate. These are silty sands which typically occur in a dense and cemented condition. Details of site earth materials are given on the attached Test Trench Logs, Plates 2 and 3. Groundwater Subsurface water was not encountered in project test excavations to the depths explored. Project earth materials are sandy deposits which characteristically transmit surface waters to depth. However, subsurface basement or other below ground rooms should be sealed and protected from surface water intrusion. Faults/Seismicity Faults or significant shear zones are not indicated on or in 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. Hitorically, the' most significant earthquake events which affect local areas originate along well known, distant fault zones to the east and the Coronado Bank PRELIMINARY GEOTECHNICAL INVESTIGATION, PAGE 3 PARCEL 2, DONNA COURT, CARLSBAD JANUARY 5, 2000 Fault to the west. Based upon available seismic data, compiled from California Earthquake Catalogs, the most significant historiôal event in the area of the study site occurred in 1800 at an estimated distance of 12 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 0.22g 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 EQ Fault Ver. 2.01) typically associated with the fault is also tabulated. TABLE I Fault Zone Distance from the Site Maximum Probable Acceleration (R.H.) Elsinore Fault 23 miles 0.126g San Jacinto Fault 46 miles 0.063g Coronado Bank Fault 22 miles 0.138g Newport- Inglewood Fault 9 miles 0. 143g The location of significant faults and earthquake events relative to the study site are depicted on a Fault - Epicenter Map attached to this report as Plate 4. More recently, the number of seismic events which affect the region appear to have increased. 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 resuiting 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 PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 4 PARCEL 2, DONNA COURT, CARLSBAD ' JANUARY 5, 2000 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. Recent trenching along the fault in Rose Canyon indicated that at that location the fault was last active 6,000 to 9,000 years ago. Thus, the fault is classified as "active" by the State of California which defines faults that evidence displacement in the previous 11,000 years as active. More active faults (listed on the preceding page) are considered most likely to impact the region 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, specific site seismic parameters were determined as part of this investigation in accordance with the Uniform Building Code. The following parameters are consistent with the indicated project seismic environment and may be utilized for project design work: TABLE 2 Site Soil Profile Type Seismic Zone Seismic Zone Factor Seismic Source Type Seismic Response Coefficients Na Nv Ca CV Ts To Sc 4 ( 0.4 B 1.0 1.0 0.40 0.56 0.560 0.112 According to Chapter 16, Division IV of the 1997 Uniform Building Code D. Geologic Hazards Geologic hazards are not indicated at the project site. Significant slopes are not present at or in near proximity to the property.. 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. PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 5 PARCEL 2, DONNA COURT, CARLSBAD JANUARY 5, 2000 E. Laboratory Testing/Results Earth deposits encountered in our test trench were visually examined and sampled for laboratory testing to determine their ability to support the planned structures and improvements. Based upon our test data and field exposures, site soils have been grouped into the following soil types: TABLE 3 Soil Type Description I brown to pale brown silty sand (fill/topsoil) 2 mottled-tan-gray silty sand with trace of clay (terrace deposit) The following tests were conducted in support of this investigation: Maximum Dry Density and Optimum Moisture Content: The maximum dry density and optimum moisture content of Soil Types I and 2 were determined in accordance with the ASTM 0-1557-91. The test results are presented in Table 4. TABLE 4 Location Soil Type Maximum Dry Density (Ym-pcf) Optimum Moisture Content (wopt-%) T-I@3' 2 130.9 11.0 T-3@2' I 120.0 11.3 In-Place Dry Density and Moisture Content: I 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 method. The test results are shown on the attached exploratory trench logs at corresponding locations and presented in Table 5. PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 6 PARCEL 2, DONNA COURT, CARLSBAD JANUARY 5, 2000 TABLES Sample Location Soil Type Field Moisture Content (w-%) Field Dry Density (Yd-pcf) Max. Dry Density (Ym-pcf) Ratio Of In-Place Dry Density To Max. Dry Density* (Yd!Ym x 100) 1-1 @ 3' 2 12.9 109.7 130.9 83.8 1-1 @ 6' 2 7.1 122.7 130.9 93.8 T-1 @9' 2 6.9 117.9 130.9 90.0 T-2 @3' 2 10.9 119.5 130.9 91.3 2 8.6 118.3 130.9 90.4 T-3@6' 2 6.9 111.7 130.9 85.4 *Designated as relative compaction for structural fills. Required relative compaction for structural fill is 90% or greater. Direct Shear Test: Two direct shear tests were performed on representative samples of Soil Types I and 2. 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 6. TABLE 6 Wet Angle of Apparent Sample Soil Sample Density Int. Fric. Cohesion Location Type Condition (Yw-pcf) (4-Deg.) (c-ps 1-1 @ 3' 2 remolded 130.2 32 150 1-3 @ 2' 1 remolded 118.6 28 25 Expansion Index Test: One expansion index test was performed on a representative sample of Soil Type I in accordance with the Uniform Building Code Standard 18-2. The test result is presented in Table 7. PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 7 PARCEL 2, DONNA COURT, CARLSBAD JANUARY 5, 2030 TABLE 7 Sample Location Soil Type Remolded w (%) Saturation (%) Saturated w (%) Expansion Index (El) Expansion Potential T-3 @ 2' 1 - - - [_non expansive very low (w) = moisture content in Dercent VI. CONCLUSIONS Based upon the foregoing investigation, development of the Study site for residential purposes is feasible from a geotechnical viewpoint. The property is underlain at depth by terrace deposit soils that are mantled by a cover of old fill and topsoil. Terrace deposit soils are typically weathered within the upper exposures, becoming dense and more cemented units with depth that will provide good support for planned improvements. Upper soils occur in a loose condition and should be regraded in connection with site development as recommended below. The following conditions are unique to the site and will impact development procedures: * Existing fill and topsoil are not suitable for the support of new fills, structures and improvements. Onsite fill and topsoil should be over-excavated and reprocessed for reuse in the new compacted fill as recommended in the following sections. Expansive soils (El)20) are not indicated at the site and' will not be a factor in the development of the project. Foundation bearing soils at the final pad grades, however, should be tested at the completion of rough grading to confirm expansion characteristics of the foundation bearing soils which will govern final foundations and slab design. Expansive soils will require special design which typically includes deeper foundations and thicker slab-on-grade floors. Based upon the project grading scheme and recommendations provided herein, onsite bearing soils are expected to consist of silty sandy soils (SM) with "very low" expansion potential, (El(21) according to the Uniform Building Code classification. Actual classification and expansion characteristic of the finish grade soil mix can only be provided in the final as-graded compaction report based upon proper testing of foundation bearing soils when rough finish grades are achieved. * Natural groundwater is not expected to impact project grading or the long term stability of the developed lot. Adequate site surface drainage control, however, is a critical factor in the future stability of the developed property. Additionally, effective waterproofing of below ground walls is essential. PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 8 PARCEL 2, DONNA COURT, CARLSBAD JANUARY 5, 2000 * Cut/fill transition will not be a factor in the site development provided our ground improvements and removal/recompaction recommendations are followed. * The project site is gently sloping terrain and the proposed graded slopes are minor - in the order of 10 feet maximum. Slope stability will not be a factor in the site development provided our grading recommendations are followed. * Liquefaction and seismically induced settlements will not be factors in the development of the proposed structures and improvements, provided our soil treatment recommendations are implemented during the grading operations. * Post construction settlements after building construction are not expected to be a factor in the development of the project site, provided our site improvements and foundation recommendations are implemented during the construction phase of the project. * Soil collapse will. not be a factor in development of the study site, provided our recommendations for site development are followed. VII. RECOMMENDATIONS The following recommendations are consistent with the project geotechnical conditions and proposed scheme of site development as planned: A. Grading and Earthworks Cut/fill grading techniques may be used in order to achieve final design grades and improve soil conditions beneath the new structures and improvements. All grading and earthworks should be completed in accordance with Appendix Chapter 33 of the Uniform Building Code, City of Carlsbad Grading Ordinances, the Standard Specifications for Public Works Construction and the requirements of the following sections wherever applicable: 1. Cleaning and Grubbing: Surface debris, vegetation and other unsuitable materials should be removed from the areas proposed for grading, new fills and support of structures and improvements plus 10 feet. Removals should be inspected and approved by the project geotechnical engineer or his designated field representative prior to grading. PRELIMINARY GEOTECHNIAL INVESTIGATION PAGE 9 PARCEL 2, DONNA COURT, CARLSBAD JANUARY 5, 2000 2. Removals and Over-Excavation: The most effective soil improvement method to mitigate the loose upper fills and unstable weathered terrace deposits, will utilize removal and recompaction using cut/fill grading techniques. Upper loose soils and weathered terrace deposits-within the areas prepared for grading as indicated above, should be removed to the underlying competent terrace deposits as approved by the project soils engineer, and placed back as properly compacted fill. All over-excavations should extend a minimum of 10 feet beyond the outside perimeter of the proposed building, fills, and improvements. The approximate removal depths in the vicinity of individual exploratory test trenches are shown on Plate I and tabulated on Table 8. Locally deeper removals may be necessary based upon the actual field exposures and should be anticipated. TABLE 8 Trench Location Total Depth of Trench (ft) Estimated Depth of Over- Excavation (ft) Comments 1-1 10' 4' cut ground, depth of undercut may govern T-2 8' 2' daylight, depth of undercut may govern T-3 7' 6' fill slope areas Notes: All depths are measured from the existing ground levels. Actual depths may vary at the time of construction based on seasonal conditions and actual subsurface exposures. Bottom of all removals should be prepared prior to fill placement as directed in the field. 3. Cut/Fill Transition: Cut/fill transition should not be allowed under buildings, improvements and the associated structures. In the event of cut or shallower removal depths to the underlying bedrock, the cut portion of the building pad should be additionally undercut to provide a minimum of 3 feet of compacted fill below the rough finish grades, or 1-foot below the deepest footing (whichever is more). There should also be at least 1-foot of compacted fill below the rough finish subgrade underneath all onsite improvements. 4. Fill Materials and Compaction: Onsite excavations will generate sandy soils which will work well as compacted fills. Site soils should be moisture conditioned to near optimum levels, placed in thin uniform horizontal lifts and PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 10 PARCEL 2, DONNA COURT, CARLSBAD JANUARY 5, 2000 mechanically compacted to a minimum of 90% of the corresponding laboratory maximum dry density, (ASTM D-1 557-91) unless otherwise specified. Permanent Graded Slopes: Graded cut/fill slopes should be programmed for 2:1 gradients maximum. Graded slopes constructed at 2:1 gradients will be grossly stable with respect to deep seated and surficial failures for the indicated maximum vertical heights. All fill slopes shall be provided with a lower keyway. The keyway should maintain a minimum depth of 2 feet into the competent terrace deposits with a minimum width of 12 feet, or as directed in the field by the project soils engineer. The keyway should expose firm terrace deposits throughoutwith the bottom heeled back a minimum of 2% into the natural hillside and inspected and approved bythe .project soils engineer or his designated representative. Additional level benches should be excavated into the dense terrace deposits as the fill slope construction progresses. It is recommended that all fill slopes be overbuilt and then cut back to the proposed design configuration or backrolled at a minimum of 4-foot vertical increments and "track-walked" at the dompletion of grading. Field density tests should be performed to confirm adequate compaction levels within the slope face. Over cutting of the proposed graded cut slopes may result in costly repairs and should be avoided. Cut slopes should be inspected by the project geotechnical consultant at the time of excavations to confirm geologic structure and slope stability. Surface Drainage/Erosion Control: A critical element to the continued stability of the graded building pads, and slopes is an adequate surface drainage system and protection of the slope face. This can most effectively be achieved by appropriate vegetation cover and the installation of the following systems: * Drainage swales should be provided at the top and toe of the slopes, per the project civil engineer design. * Building pad and slope surface runoff should be collected and directed to a selected location in a controlled manner. Area drains should be installed. The finish slope should be planted soon after completion of grading. Unprotected slope faces will be subject to severe erosion and should not be PRELIMINARY GEOTECHNICAL INVESTIGATION ' S PAGE 11 PARCEL 2, DONNA COURT, CARLSBAD JANUARYS, 2000 allowed. Over-watering of the slope face should also not be allowed. Only the amount of water to sustain vegetation life should be provided. . 7. Engineering Inspections: 'All grading operations including removals, . suitability of earth deposits used ascompacted fill, and compaction procedures. should be continuously inspected and tested by the project geotechnical consultant and presented in the -fihal as-graded compaction'report. The nature of finish subgrade soils should also be confirmedin the final compaction report at the completion of grading. Geotechnical engineering inspections shall include, but not limited to the following: S * Initial inspection - After the grading/brushing limits have been staked, but before grading/brushing starts. . . * Keyway/bottom of over-excavation inspection - After the natural ground or bedrock is exposed and prepared to receive fill, but before fill is placed. * Cut slope/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 inspection - After the fill placement is started, but before the vertical .height of fill exceeds 2 feet. -Finish pad grade tests 'will be required regardless of the fill height. * Foundation trench inspection - After- foundation trench excavations, but before steel placement. * Foundation bearing/slab subgrade soils inspection - Within 72 hours prior to the placement of concrete for proper moisture and specified compaction levels. * Foundation/slab steel inspection After steel placement is completed, but 24 hours before the scheduled concrete pour. . Subdrain/wall backdrain inspection - After the trench excavation, but during the actual placement. All material shall conform to the project material specifications and be approved by, the project soils engineer. PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 12 PARCEL 2, DONNA COURT, CARLSBAD JANUARY 5, 2000 * Underground/utility trench inspection - After the trench excavations, but before installation of the underground facilities. Local and CAL OSHA safety requirements for open excavations apply. Inspection of the pipe bedding may also be required by the project soils engineer. Underground/utility 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. " * Pavement/improvements subgrade and basegrade inspections - Within 72 hours 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 "very low" expansive bearing soils(El(21) expected at pad grade. Final designs should be confirmed and/or revised as necessary in the rough grading compaction report based upon site as- graded geotechnical conditions and actual testing of the foundation bearing earth materials. Additional specific recommendations may also be necessary and éhould be given at the time of the plan review when structural/architectural drawings are also available. The proposed building can be supported, on stiff shallow foundations. The shallow foundations should be founded on certified foundation bearing soils. Acceptable foundations should include a system of spread pad and strip footings and slab-on-grade floors. Continuous strip concrete foundations should be sized at least 12 inches wide and 12 inches deep for 1-story' structures and at least 15 inches wide and 18 inches deep for 2-story structures., Interior and exterior spread pad footings should be at least 24 inches square and 12 inches deep. Footing depths are measured from the lowest finish rough grade not including the sand/gravel underlay beneath the slabs. Exterior continuous strip footings should enclose the entire building perimeter. Interior and exterior continuous strip foundations should be reinforced by at least 244 reinforcing bars. Place 144 bar 3 inches above the bottom of the PRELIMINARY GEOTECHNICAL INVESTIGATION - PAGE 13 PARCEL 2, DONNA:COURT, CARLSBAD JANUARY 5, 2000 S. footing and 144 bar 3 inches below the top of the footing. Reinforcement details for spread pad footings should be provided by the project structural engineer.. 4. Interior slabs should be a minimum of 4 inches in thickness reinforced with #3 reinforcing bars spaced 18 inches oncenter each way, placed mid-height in the slab. Slabs should be underlain with 4 inches of clean sand (SE 30 or greater). - Place a six-mil plastic moisture barrier mid-height in the clean sand. Slab subgrade soils should be tested for proper moisture and specified compaction levels and approved by the project geotechnical cohsultánt within 72 hours priorto the placement of concrete. 5. Provide contraction joints consisting of sawcuts spaced 10 feet on center, maximum each way within 24 hours of concrete pour fora11 interior slabs. The sawcuts should be a minimum of 1-inch in depth and not to exceed 1%-inches- in depth. 6. Provide re-entrant corner reinforcement for all interior slabs in general accordance with the attached Plate 5. Re-entrant corners will depend on-slab geometry and/or interior column locations. C. Exterior Concrete Flatworks • - - All exterior slabs (walkways, patios) should be a minimum of 4 inches in thickness reinforced with 6x6/.10x10welded wire mesh carefully placed mid- height in the slab. • . . • . - Concrete driveways and parking Slabs supported on non expansive subgrade for residential developments should be a minimum of 5 inches in thickness reinforced with #3 bars at 18 inches on center each way, placed mid-height in the slab. Provide .a minimum of 6 inches of 95% compacted subgrade beneath the PCC driveway and parking slabs. - 3. Provide contraction joints Oonisting of sawcuts spaced 10 feet (not to exceed - • • • 12 feet maximum) on center each way within 24 hours of concrete pour for.all exterior slabs. The sawcuts should be a minimum depth of 1-inch but not to - exceed 1%-inches deep. • 4. All exterior slab designs should be confirmed in the final as-graded compaction report. •• PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 14 PARCEL 2, DONNA COURT, CARLSBAD.. JANUARY 5, 2000 5. Subgrade soils should be tested for proper moisture and specified compaction levels and approved by the project geotechnical consultant within 72 hours prior to the placement of concrete. !I1Imnii thiFr1 The following soil design parameters are, based upon the tested representative samples of onsite earth deposits. All parameters should be confirmed and/or revised when characteristics of the final as-graded sails have been specifically determined: Design wet density of soil = 130.2 pcf. Design angle of internal friction of soil = 32 degrees. Design active soil pressure for retaining structures = 40 pcf (EFP), level backfill, cantilever, unrestrained walls. Design at-rest soil pressure for retaining structures = 62 pcf (EFP), non- yielding, restrained walls. Design passive soil pressure for retaining structures = 423 pcf (EFP), level surface at the toe; - Design coefficient of friction for concrete on soils = 0.39. Allowable foundation pressure for compacted fill (12" wide by 12" deep footings) = 1000 psf. Allowable foundation pressure for compacted fill (15" wide by 18" deep footings) = 1500 psf. . Allowable lateral bearing pressure (all structures except retaining walls) for compacted fill = 100-psf/ft. Notes: * Because large movements must take place before maximum passive resistance can be developed, a minimum safety factor of two should be considered for sliding stability where structures and improvements are planned on top of the wall. * When combining passive pressure and frictional resistance, the passive component should be reduced by one-third. * The allowable foundation pressures provided herein applies to dead plus live loads and may be increased by one-third for wind and seismic loading. PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 15 PARCEL 2, DONNA COURT, CARLSBAD ' JANUARY 5, 2000 * The lateral bearing earth pressures may be increased by the amount of the designated value for each additional foot of depth to a maximum of 1,500 pounds per square foot. E. Asphalt Pavement Design Specific pavement designs can best be provided at the completion of rough grading based upon R-Value tests of the actual finish subgrade soils; however, the following structural sections may be considered for cost estimating purposes only . (not for construction). 1. A minimum section of 3-inches asphalton6 inches of CaltransClass,ll base may be considered. Base materials should be compacted to a minimum of• - 95% of the maximum dry density. 2.. Subgrade soils beneath the asphalt roadway, parking and driveways should be compacted to a minimum of 95% of the corresponding maximum dry density within the upper 1-foot. Subgrade and basegrade soils should be tested for proper moisture and a minimum of 95% compaction levels and approved by the project geotechnical consultant within 72 hours prior to the placement of the base or asphalt layers. • . • • 3 Base section and subgrade preparations per structural section design, will be • required for all surfaces subject to traffic including roadways, traveiways, driveway approaches, and ribbon (cross) gutters. Due to non expansive subgrade soils, however, base section may not be required under curb and gutters, and sidewalks. 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 upon soil characteristics only and is not intended to be in lieu of reinforcement necessary for structural considerations. All recommendations should be evaluated and confirmed be the project architect/structural engineer. PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 16 PARCEL 2, DONNA COURT, CARLSBAD JANUARY 5, 2000 Footings located on or adjacent to the top of slopes sh9u1d be extended to a sufficient depth to provide a minimum horizontal distance of 7 feet or one-third of the slope height, whichever is greater (need not exceed 40 feet maximum) between the bottom edge of the footing and face of slope. This requirement applies to-all improvements and structures including fences, posts, pools, spas, etc. Concrete and AC improvements should be provided with a thickened edge to satisfy this requirement. 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 finish surface. Retaining walls should be provided with a back drainage in general accordance with the attached Plate 6. All underground utility trenches should be compacted to a minimum of 90% of the maximum dry density of the soil unless otherwise specified by the respective agencies. Care should be taken not to crush the utilities or pipes during the compaction of the soil. Non-expansive, granular backfill soils should be used. Site drainage over the finish pad surface should flow away from structures on to the street in a positive manner. Care should be taken during the construction, improvement, 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 building and structures to a suitable location. Considerations should be given to adequately damp-proofing/waterproofing the basement walls/foundations and provide the planter areas adjacent to the foundations with an impermeable liner and a subdrainage system. Project grading and foundation plans should reflect preliminary recommendations given in this report. We suggest that final grading and foundation plans to be reviewed by the project geotechnical consultant for conformance with the soils report. More specific recommendations can be provided when final drawings are available. 7.. 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. PRELIMINARY GEOTECHNICAL INVESTIGATION 0 PAGE 17 PARCEL 2, DONNA COURT, CARLSBAD . JANUARY 5, 2000 8. The amount of shrinkage and related cracks that occurs 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: * 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 three-eights inch, maximum size aggregate usually requires about 40 !bs more (nearly 5 gal.) water per cubic yard than concrete with one 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. 9. A preconstruction meeting between representatives of this office and. the property owner' or planner, the city inspector, as well as the grading contractor/builder, is recommended in order to discuss grading/construction details associated with site development. 0 VIII. LIMITATIONS The conclusions and recommendations provided herein have been based on all available data obtained from 'research and review of pertinent geotechnical reports and plans, exploratory subsurface 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. . PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 18 PARCEL 2, DONNA COURT, CARLSBAD JANUARY 5, 2000 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. The property owner(s) should be aware of the development of cracks in all concrete surfaces such as floorslabs and exterior stucco 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 ½-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 yearand is subject to review by our firm following that time. If significant modifications are made to your architectural plans and tentative development plan, especially with respect to type and location of the buildings as well as 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 #99-384-P will help to expedite our response to your inquiries. PRIMARY DIVISIONS GROUP SECONDARY DIVISIONS SYMBOL GRAVELS CLEAN GW Well graded gravels, gravel-sand mixtures, little or no fines. GRAVELS MORE THAN HALF (LESS THAN GP Poorly graded-gravels or gravel-sand mixtures, little or no fines. OF COARSE 5% FINES) GM Silty gravels, gravel-sand-silt mixtures, non-plastic fines. CO FRACTION IS GRAVEL LL 2 W W Oz! LARGER THAN WITH LL < Cl) NO. 4 SIEVE FINES GC Clayey gravels, gravel-sand-clay mixtures, plastic fines. LU ( SANDS CLEAN SW SANDS Well graded sands, gravelly sands, little or no fines. MORE THAN HALF (LESS THAN SP Poorly graded sands or gravelly sands, little or no fines. iCC OF COARSE 5% FINES) SANDS 8 w FRACTION IS SM Silty sands, sand-silt mixtures, non-plastic fines. CC W SMALLER THAN WITH NO. 4 SIEVE NO. FINES Clayey sands, sand-clay mixtures, plastic fines. LU ML Inorganic slits and very fine sands, rock flour, silty or clayey fine N . o w cn SILTS AND CLAYS sands or clayey silts with slight plasticity. CL Inorganic clays of low to medium plasticity, gravelly clays, sandy lean clays, clays. LIQUID LIMIT IS LESS THAN 5O% _silty _clays, CL 0 00 Organic silts and organic silty clays of low plasticity. uj MH Inorganic silts, micaceous or diatomaceous fine sandy or silty < I . W wE0 SILTS AND CLAYS soils, elastlô silts. CH Inorganic clays of high plasticity, fat clays. w LU Z z 0 LIQUID LIMIT IS GREATER THAN 50% OH Organic clays of medium to high plasticity, organic slits. HIGHLY ORGANIC SOILS . PT I Peat and other highly organic soils. GRAIN'SIZES U.S. STANDARD SERIES SIEVE CLEAR SQUARE SIEVE OPENINGS 200 40 10 4 3/4" 3" 12" SAND I GRAVEL SILTS AND CLAYS I I 1COBBLES BOULDERS FINE I MEDIUM I COARSE I FINE I COARSE I RELATIVE DENSITY SANDS, GRAVELS AND NON-PLASTIC SILTS BLOWS/FOOT VERY LOOSE 0 - 4 LOOSE 4-10 MEDIUM DENSE 10 -30 DENSE 30 -50 VERY DENSE OVER 50 CONSISTENCY CLAYS AND PLASTIC SILTS STRENGTH BLOWS/FOOT VERY SOFT 0-'/. 0-2 SOFT - V- '/ 2-4 FIRM 'Ia - I 4-8 STIFF 1-2 8-16 VERY STIFF 2-4 16-32 HARD OVER 4 OVER 32 1. Blow count, 140 pound hammer falling 30 inches on 2 inch O.D. split spoon sampler (ASTM 0-1586) 2 Unconfined compressive strength per SOILTEST pocket penetrometer CL-700 A = undisturbed chunk sample 246 = Standard Penetration Test (SPT) (ASTM D-1 586) with blow counts per 6 Inches El disturbed sample = - 246 = California Sampler with blow counts per 6 inches = sand cone test 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: 1222-99 . Logged by: DM TI -' .. FIELD DEPTH SAMPLE USCS SYMBOL FIELD MOISTURE DRY DENSITY RELATIVE COMPACTION . DESCRIPTION . (%) (pci) (%) -0- FILL: .•. ' SM - I - Silty sand. Brown. Dry, loose. - 2 -- ST-I' - 3 - l u .. . . ' 12.9 109.7 83.8 - 4 - TERRACE DEPOSIT:- - 5 - . Silty fine sand. Yellow-brown. Trace of clay. Cemented SM - 6 - friable.. Massive. Moist.. 7..1 122.7 93.8 -7- - 8-- ' From 5', sandis cemented, very tight. 6.9 117.9 90.0 g U - . . ' •ST-2 S -10— - Ii - End Trench at 10'. -12- . 0 Date: 12-22-99 " Logged by: DM DEPTH (ft) SAMPLE T U L. USCS SYMBOL . FIELD MOISTURE (°') FIELD DRY DENSITY ' (Pci) RELATIVE' COMPACTION • DESCRIPTION' ' ' - 0 - TOPSOIL: . - - Silty fine sand. Brown. Porous. Dry, loose. SM -1- . •. •. I si-i • 2 TERRACE DEPOSIT:.• . . . -. - Silty sand with trace of clay. .Mottled tan/gra'y'. Cemented - - 0 firm. Massive. . 10.9 119.5 91.3 -4- • ' ' -5- •0 : 6 :. . SM 8.6 '118.3. 90.4 - - . ST-2 -7- . . ' •0 End Trench at 8'. - . . • VINJE & MIDDLETON ENGINEERING, INC ' TEST TRENCH LOGS .. 2450 Vineyard Avenue, Suite 102 Escondido, California 92029-1229 DONNA COURT, CARLSBAD PROJECT NO. 99-384-P PLATE 2 Office 760-743-1214 Fax 760-739.0343 --V L Sand Cone Test 0 Bulk Sample 0 Chunk Sample .--.0 Driven Rings Date: 12-22-99 Logged by: DM FIELD ____________________________________________________ USCS FIELD DRY RELATIVE DEPTH SAMPLE SYMBOL MOISTURE DENSITY COMPACTION (ft) DESCRIPTION (%) (pci) (%) - 0 - FILL/TOPSOIL: - Silty fine sand. Pale brown. Dry, loose. -1- 'SM : 2 TERRACE DEPOSIT: - 3 •- Silty sand. Yellow-brown. Massive. Cemented, tight. -4-U - 'ST2 SM 5 .- 6.9. 111.7 85.4 . :6 : - 7 - - End Trench at 7'. -8- Date: ,' . Logged by: FIELD USCS FIELD DRY RELATIVE DESCRIPTION DEPTH (ft) SAMPLE SYMBOL MOISTURE (%) DENSITY (pci) COMPACTION (% -0- -1- -2- -3- -4- -5- ' -6- -7- VINJE & MIDDLETON ENGINEERING, INC TEST TRENCH LOGS 2450 Vineyard Avenue, Suite 102 Escondido, California 92029-1229 DONNA COURT, CARLSBAD PROJECT NO. 99-384-P PLATE 3 Office 760-743-1214 Fax 760-739-0343 L--V Sand Cone Test 0 Bulk Sample L Chunk Sample 0 Driven Rings -c2- 3' 4/ \ \.•. \. .-.. e J P . ,. NT ja ao,0 \ 81 d3 0 —10 2. Son theg 0 0 30 20 10 0 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 ..............4.0T04.9 O ............5.0T05.9 ED ............6.0 TO 6.9 - PROJECT: 99-384P 7.0 TO 7.9 DONNA COURT, (RRSBAD Fault. PLATE NO. 4 (a) - (b) TION JOINTS RACTION JOINTS (c) ISOLATION JOINTS AND RE-ENTRANT CORNER REINFORCEMENT Typical - no scale RE-ENTRANT CORNER CRACK RE-ENTRANT CoRNER ----- REINFORCEMENT N014 BARS PLACED 1.5" BELOW TOP OF SLAB NOTES: 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 Ad). In order to control cracking at the re-entrant corners (±2700 corners), provide reinforcement as shown in (c). 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 5' Waterproofing - - Perforated drain pipe — RETAINING WALL DRAIN DETAIL Typical -.no scale drainage .f- - -- , •v, .. -, '. ,- :>4. '1.•. Granular, non-expansive y' 01 01 backfill Compacted,,, " EX i- Filter Material Crushed rock (wrapped in ' ' A L.) filter fabric) or Class 2 Permeable Material .(see specifications below) 0 •___ * t SP FOAL1tAN$ " * I ts.s'rANDARD Competent, approved 'I WIN soils or bedrock 3(4 - 90-lOU 3J8 'CONSTRUCTION SPECIFICATIONS: Provide granular, non-expansive backfill soil In 1:1 gradient wedge behind wall. Compact backfill to minimum 90% of laboratory standard. 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 16/6. Provide %- 1W 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 tomihimum 90% of laboratory standard. Seal back of wall with waterproofing in accordance with architects specifications. - Provide positive drainage to disallow ponding of water above wall Uned drainage ditch.to • minimum 2% flow away from wall Is recommended. - - *Use 1,4 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 6