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HomeMy WebLinkAboutCT 03-06; BLACK RAIL 16; PRELIMINARY GEOTECHNICAL INVESTIGATION; 2003-05-22Preliminary Geotechnical Investigation Proposed 17-1_ot Subdivision Black Rail Road, Carlsbad (A-P.N.-#215-080-20, 21, 28) May 22, 200 •' Prepared For: TABATA BROTHERS Attention: 'Mr. Noboru Tabata do Mr. GregHarrington P.O.: Box 679 Carlsbad, California 92018 Prepared By: VINJE & MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue,. Suite 102 Escondido, California 92029 Job #03-236-P t( VINJE & MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue Escondido, California 92029-1229 Job #03-236-P Phone (760) 743-1214 Fax (760) 739-0343 May 22, 2003 Tabata Brothers Attention Mr. NobôrU Tabata do Mr. Greg Harrington P.O. Box 679 Carlsbad, California 92018 PRELIMINARY GEOTECHNICAL INVESTIGATION, PROPOSED 17-LOT SUBDIVISION, BLACK RAIL ROAD, CARLSBAD, (A.P.N. #215-080-20,211, 28) Pursuant to your request, Vinje and Middleton Engineering, Inc., has completed the Preliminary Geotechnical Investigation Report for the above-referenôed project site. The following report summarizes the results of our research and; review of pertinent geotechnical maps and reports, subsurface field investigation and soil sampling, laboratory testing, engineering analyses and provides conclusions and construction recommendations for the proposed development as understood. From a geotechnical engineering standpoint, it is our opinion that the site is suitable for the proposed 17-lot residential subdivision and the associated improvements provided the recommendations presented ir this report are incorporated into the design and reconstruction of the project. The conclusions and recommendations provided in this study are consistent with the indicated site geOtechnical conditions and. are intended to aid in preparation of final development plans and allow more accurate estimates of the construction'. costs. If you have any questions or need clarification, please do not hesitate to contact this office. Reference to our Job #03-236-P will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJE & MIDDLETON ENGINEERING, INC. Zo Dennis Middleton . CEG #980 CERTIFIEDENGINE RING * DMIt TABLE OF CONTENTS PAGE NO. INTRODUCTION ......................................................I SITE DESCRIPTION ........................................ . ......... I 111. PROPOSED DEVELOPMENT .......................................2 IV. SITE INVESTIGATION .............................................2 V. GEOTECHNICAL CONDITIONS ........................................ 2 Earth Materials ..................................................3 Groundwater ................................................... 3 Slope Stability .....................................................3 Faults I Seismicity .................................................4 Geologic Hazards .................................................6 Laboratory Testing I Results ........................................6. VI. CONCLUSIONS . ..................................................9 VII. RECOMMENDATIONS ..............................................11 Grading and Earthworks . ... .................................. 11 FoundatiOns and Interior Floor Slabs ................................... 17 Exterior .Concrete Slabs / Flatworks ................................18 Soil Design Parameters ................................................ 19. Asphalt and PCC Pavement Design ................................20 General Recommendations ......................................2.1 VIII. LIMITATIONS ....................................................23 TABLE NO. Fault Zone .............................................................. Site Seismic Parameters ...............................................2 SOilType .............................................................3 Maximum Dry Density and Optimum Moisture Content ....................... 4 Moisture-Density Tests (Undisturbed Chunk Samples) .....................5:. Expansion Index Test .......................................... .......6 ((. Direct Shear Test ........................................................7 TABLE OF CONTENTS (continued) Ph and Resistivity Test ..................................................8 SulfateTest ...........................................................9 Years to Perforation of Steel Culverts ..................................10 PLATE NO. Regional Index Map .................................................... I SitePlan ...............................................................2 Original Features Map ....................................................3 Geologic Cross-Section A-A ...... ........................................4 Test Trench Logs (with key) ..........................................57 Fault-Epicenter Map .......................................................8 Isolation Joints and Re-entrant Corner Reinforcement 9 Retaining, Wall Drain Detail ...............................................10 PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED 17-LOTSUBDIVISION - BLACK RAIL ROAD, CARLSBAD I. INTRODUCTION The propert' investigated for this work includes three parcels with a total area of 5.24 acres located on the east side of Black Rail Road within the city of Carlsbad. The site. location. is shown on a Regional Index Map enclosed this report as Plate t We u,ndersta'hd the property is planned for a 17-lot subdivision one interior street with cul-de-sac, and associated improvements. Consequently, this investigation was initiated to determine soils conditions at the property. and their influence upon the planned development. Geologic mapping, test trench .digging,,and soii sampling and testing were among the activities. conducted in conjunction with this effort which has resulted-in the gebtéchnicàl engineerihg planning and development, recommendations presented herein: SITE DESCRIPTION The rectangular-shaped study property is locéted within the City of Carlsbad add situated ( south of e! water-tank site and north of residential developments. Black Rail Road marks the Upper (west) boundary and undeveloped hillside terrain borders the eastern riiarinbf the' site. A Site Plan, supplied by Pasco Engineering, depicts existing topographic conditions and proposed development, and is included with this report as Plate 2. The site, is presently used fOr agricultural purposes. At .the time. of this investigation strawberry' fields mantled nearly'the entire southern half of the site and a section' in the north-central portion of the property. An A-frame structure with associated improvements is located in the northwest portion along with a small greenhouse The eastern edge of the property is used for storage and includes several träilOrs and miscella'nëousagriôultural equipment. A fill slope, With gradient approaching nearly 1:1 (horizontal to vertil)' marks the eastern margin of the study site The slope is associated with a large section of fill placed into original canyon terrain at the east end of the property, presumably in order to' enlarge 'level areas. The fill was placed Without engineering observation or testing 'and may reach more than 30-feet in thickness. Additional shallow fills mantle much of the 'remainder of the site and, locally are undifferentiated from project topsoils. Dump fills have recently been placed in the northeasterly area of the site. ' VINJE & M1DJLETON ENGINEERING, INC. 2450 \neyard Avenue, Escondido, California 92029-1229 • Phone (760) 743-1214 • Fax (760) 739-0343 QEOTEC4N1CAL-INSTIQXT1ONS GRADING SUPERVISION PERC TESTING' ENVIRONMENTAL INVESTIGATION PRELIMINARY GEOTECHNICAL INVESTIGATION V PAGE 2 ç BLACK RAIL ROAD, CARLSBAD, CALIFORNIA V MAY 22-1 2003 Original site topography is shown on an Original Features Map, copied from the County of San Diego Topographic Survey, sheets No. 342-1677 (photographed 9-17-75) and 342- 1683 (photographed 9-18-75) and included herein as Plate 3. A Geologic Cross-Section' depicting original and existing site topography is enclosed as Plate 4. Site drainage sheefflows in a generally easterly direction to the aforementioned. fill slope. Excessive. scouring and erosion from uncontrolled run-off is not jfl evidence at the site, however, nearby bad land topography does evidence significant erosional features Ill. PROPOSED DEVELOPMENT As seen on Plate 2, the study property is planned for a 17-lot residential subdivision with an internal road and associated improvements. Final elevations and detailed grading scheme are not yet available. It is anticipated that conventional cut / fill grading techniques will be utilized for the creation of level building pads at or very near existing grades. Proposed cut I fill slopes are planned for 2:1 gradients and are expected to reach moderate heights. S . Details of building construction are also unknown. However, the use of conventional Wood- frame and stucco buildings supported by continuous strip and spread pad concrete footings with slab-on-grade floor foundations is assumed for the purpose of this study. SITE INVESTIGATION Subsurface conditions within the study area were chiefly determined by geologic mapping of local exposures and. the excavation of 6 test trenches dug with a tractor-mounted backhoe. Trench locations were limited due to existing structures / storage trailers, agricultural improvements, and strawberry fields. All trenches were enterédandloged by our project geologist, who also retained soil I rock samples for subsequent laboratory testing. Test trench locations are shown on Plate 2. Logs of the test trenches are included as Plates 5-7. Laboratory test results are summarized in a following section. GEOTECHNICAL CONDITIONS The study property is underlain by competent Terrace Deposit units. The eastern margin of the site supports a thick deposit of undocumented fills. Elsewhere, thin deposits of fill I topsoils -mantle project Terrace Deposits. VINJE & MIDbLETON ENGINEERING, INC. 2450 Vineyard Avenue, Escondido, California 92029-1229 1. Phone (7601).743-1214 • Fax (760) 739-0343 QEOTECflJICAL-INVES7I(flONS GRADING SUPERVISION . PERC TESTING ENVIRONMENTAL INVESTIQATION PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 3 C BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 Earth Materials The following earth materials are recognized at the project site: Terrace Deposit Sedimentary formational units underlie site fills I topsoils at the property. These are natural Pleistocene age Terrace Deposits .which Oons,ist Of light-colored sandstone units that are widely exposed throughout the area in upper ridge terrain. As exposed in our test trenc,hes, the sedimentary units typically consist of fine, to medium sandstone found in a general blocky and well-cemented condition. Project Terrace Deposits are competent units which will provide adequate support for the planned development. Topsoil - A thin veneer of topsoil overlies site Terrace Deposits.. Topsoils consist of silty to clayey sand found in a general moist and blocky condition. Fill - A thick deposit of old fill soil occu3ies.&iginal canyon terrain at the eastern margin, of the site (see Plate 4) Existing fill soils may reach more than 30 feet in thickness and consist of mixtures of sands and clays. In Test Trench I (T-1) asphalt and concrete debris Up. to 2 feet. in diameter'and comprising up to 50% of the fill were encountered below 10 feet. Existing fills were found in a Moist and (. . very loose to locally medium dense condition overall. Site existing fills and topsoils are not suitable for support of new fills, strUOtures and improvements in their present condition. Based on our field observations, project Terrace Deposit soils are non expansive to. very low expansive, while Upper. fill I topsoil materials range from very low to locally medium expansive. Details of project earth materials are given on the enclosed Trench Logs, Plates 5-7. Engineering properties are further defined ma following section. Groundwater Subsurface water was not encountered in project test excavations to the depths explored. In general, natural groundwater is not expected. to impact project grading or the longterm stability of the developed site. Slope Stability The project site is a relatively level parcel bound only along the east side by descending slope terrain consisting of fill soils placed over badland canyon topography. The eastern 1:1 gradient slopes associated with the old flllsection are ( viewed as marginally stable and not desirable at the redeveloped propérty. VINJE & M1LDLETON ENQINEERINQ, INC. 1450 Vineyard Avenue, Escondido,'CaIiforna 92029-1229 • Phone (760) 743-1214' Fax (760) 739-0343 QEQTECHNICAL INVESTIQATIONS GRADING SUPERVISION . PERC TESTING . JFNVIRO?,~N'AL INVESTIQAflUN" 1 -. . . - - 4 .. - - 4- ,. -4 .- PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 4 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 Off-site natural terrain is impacted by significant erosion creating bdIand topography. However, landsliding or other forms of mass wasting are not in - evidence in the noted exposures. Local Terrace Deposits and underlying bedrock materials are flat-lying sandstone units which characteristically perform well with regard to gross stability and are, expected to remain stable. - 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 et'énts which. ffebt local areas originate along well known, distantfaultzonesto.th eastand 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 '8 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 ac'celeratior values of 0.117 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 VERSION 3.00 updated) typically associated with the fault is also tabulated TABLE Rose Canyon fault - • - - . 5 miles . 0.180g - - Newport-lhglewood fault • 9 miles - 0.133g. 4- - Coronado Bank fault .. 21 miles 0'141.' Elsinore fault -. 24 miles' VINJE & MIDDLETON ENQINEER1NQ INC 2450 Vineyard Avenue Escondido California 92d29-1229 Phone (760) 743-12 14 • Fax (760) 739-0343 QEOTECHNICAL INVESTIQA7IONS GRADING SUPERVISION PERC TESTING ENVIRONMENTAL INVESTIGATION i PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 5 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA . MAY 22, 2003 The location of significant faults and earthquake events relative to the study site are depicted on a Fault 7 Epicenter Map included as Plate 8. 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 offahore 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 it the region remains a subject of speculation among geologists; however, based upon empirical information and the recorded sOismic 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 àIOrig 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. VrNJE &MiDDLETON ENGINEERINQ, INC. 2450 Vineyard Avenue, Escondido, California- 92029-1229 4 Phone (760) 743-1214 • Fax (760) 739.0343• Q€OTECHNICALINVESTIGATIONS . GRADING SUPERVISION PERC TESTING . ENVIRONMENTAL INVESflQATION. PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 6 * 1' BLACK RAILROAD, CARLSBAD, CALIFORNIA MAY 22,-',2003 * - .Fo(designpurposs, specific site seismic párarnéters were determined as partof 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 TABLE2 IR MORE—, ,sm Sc L 0.4 J B -ItGJ1.ito.4010.5910.5911a1181 I AccordingtoChapter 16, Division IV of-the 1997 Uniform. Building Code. I E Geologic Hazards Geologic hazards are not presently indicated at the project site The existing 1:1 gradient fill slope is recommended for reconstruction as outlined in the following. if ( section...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 I Results Earth deposits encountered in our, exploratory test excavations were closely examined and sampledfor laboratorytesting. Based upon our test trench data and F field exposures site soils have been grouped into the following soil types - . -• . •. . .• - . i_ TABLE 3 rg 1 I red-brown to gray silty to clayey sand (Fill/Topsoil) 2 . brown to red-brown clayey sand to sandy, silt (Fill) - -3 . gray sand with crushed rok (class II) and clayey sand mix (Fill) 4 gray to red-brown sand (Terrace Deposit) . . 5 - olive sandy clay (Fill) -' • • - . .. •. • - ••- ••.. 0 •. ••._ •- •- . .1 . . . .,•. . -•.• - . .;• .. - - . . • - - . -•-' - -' - a'.., . - •, I. ,.• -. . •• .••. • II.. - . . a •.. .•- --- -. * . 4 . . 1.4 . . . a •. VINJE &-MIDDL-ETON ENGINEERITNQ, INC. 2450 neyatd Avenue, Escondido, California 92029-1229 • Phone (760) 743 1214 • Fai (760) 739-0343 iEOTECHNICAL INvES11ATIONs .GRADING SUPERVISION, PERC TESTINQ V ENVIRONMENTAL INVEST1QATlON * . • . . , *• • . • . . . •; ,• 4. (. PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE .7 k BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 The following tests were aonducted in support of this investigation 1. Maximum Dry Density. and Optimum M6isture Content: The maximum dry density and optimum moisture cont'ent of Soil Types 1 and 2 were deter ftiined in accordance with ASTM D-1557. The test results are presented inTable,4. .5 . . . TABLE4 . . . . .5 . ME - M1.4, .So .. Maxiniunj Q51-y 2 Moisture-Density Tests (Undisturbed Chunk Samples) In-place dry density and. moisty.re *content of representative .soil deposits beneath the sit&were determined from relatively undisturbed chunk samples using the water displacement test method.,, The test results are presented in Table 5 and tabulated on the enclosed Test Trench Logs TABLE T-1 @2' 1 '. 21.7 100.6 125.0 . 80.5 1-1 @ 5' . I . 13.6 94.1 . .125.0 . . 75.3.-- T-1 @8' 2 19.6 101.1 . '.120.3 . 84.1 T-1 @ 12' 2 31 2 88 ..6 120.3 73.7 -. 1 9.8 104.8 125:0 .83.9 T-2 @6'. 1 . 7.4. 5 - . 125.0 sample disturbed T-2 @ 7,4' 1 17.0. 102.3' 125.0 81.8 T-28' 4 . .16.5 . 105.2 T-3@5t . 4 12.7 . 110.6 . -. . .. 5 - 5 .5 . . .5 . 5 - 5 5 •. VINJE & MIDDLETON ENGINEERING INC 2450 Vineyard Avenue Escondido, California 92029-122'9 Phone (760) 743-1214 Fax (760) 739 0343 QEOTEcHNICAL INVESTIQAT1ONS QRADINQ SUPER VISION PERC TESTLNQ EWIRONMENTAL INVESTIQATION ( PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 8 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 - • . - I TABLE 5 (continued) .T-3@6' 4. 7.5 - - -117.6 - .- -• T-4@2' 1 122 1167 1250 933 T-4@6' 4 165 1006 - - T-5@3' 4 7.9 125.4 - T-6©2½ 4 111 *.Designated as 1e1ativé compaction for strucfural fills.' Required relative compaction for structural fill is 90% or greater. ji 3 Expansion Index Test Two expnsion index tests were performed on representative samples of Soil Types 1 and 2 in accordance with the Uniform Buildin..Code Standard 18-2.. The test results are presented in Table 6.. TABLE . . . . . :. ijji; -: ' u5()-. : Ii •k(Ei) . T-1 @3' 1 9.9 51.9- H8.6 23 low T-1 @12' 2 11.2 49.9 24.9 42 low . . (ci) = moisture content in percent. 4 Direct Shear Test Two direct shear tests were performed on representative samples of Soil Types 1 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 inan undrained condition. The test results - are presented in-Table 7.. - L - TABLE 7. . i: T-1 @31 1 remolded to 90% of Yd @ % oopt 124.9 31..115 ( T-1 @12' 2- rernolded to 90% of Yd @ % Wapt 124.8 29 285 VTNJE & MIDDLETONENGINEERINQ, INC. 2450 Thieyard Avenue, Escondido, California 92029-1229 • Phone (760)743-1214 .• Fax (760)739-0.43- QEOTECI{NICLThVTIkñ0NS . - GRADING SUPERVISION - PERC TESTINQ - .' . E1IVIRONMENTAL flESTIQA.ñQ4: - I • ( PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 9 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22,.2003 5 Ph and Resistivity Test Ph and resistivity of representative samples of Soil Type I collected at selected 1pOatibns 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 I p I eea I T-1 @3' I i -. .1 728. I 7.19. 6 Sulfate Test A sulfate test was performed on a representative sample of Soil Type I in accordance with the California Test 417. The test result is presented. in Table '9. TABLE 9 - - Pe~ r NWN Ism , : %— , !3 b Xi) - I T-1 @ 3' I 1 I . 0.019 ...Vi.' I CONCLUSIONS Based upon the foregoing investigation, development of the project site substantially as proposed, is feasible from a geotechnical viewpoint Much of the site is underlain by dense and sthble Terrace Deposits which are mantled by a thin section of loose to soft sandy.to clayey fill / topsoils However, the eastern margin of the site is underlain by thick Undocumented fill deposits placed over original canyon terrain in an over-steepened slope condition Geotechnical factors presented below are unique ,to the project site and will influence grad ing procedures and associated development costs * Nearby off-site natural terriri and i..indèrlyiñg Terrace Deposit sa ndstone units are geologically stable Landslides or other forms of geologic instability within the on- site natural formational deposits are not indicated The existing over-steepened loose fill slope to the east is potentially Unstable and can undergo deep and surficial failures. The slope should be removed and reconstructed to the design configurations as a properly compacted fill' . . . . - VTNJE & MIDDLETON ENGINEERING, INC 2450 Vineyard Avenue Escondido California 92029-1229 • Phone (760) 143-1214 • Fax (760) 7j9-0343' QEOTECHNIcAL1NVES7gATIONS GRADING SUPERVISION PERC TESTINQ ENVIRONMENTAL ThIVESTIQATION ( PRELIMINARY GEOTECHNICAL INVESTIGATION' PAGE 10 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 embankment. Adequate lower keyways and benches should be excavated into the natural hillside in order to construct a safe and stable fill embankment. * Removal and recompaction of the site existing loose to soft fills I topsoils and upper highly weathered exposures of the underlying Terrace' Deposits will be necessaty as recommended in the following sections. The entire section of site existing fills should be removed and recompacted. Existing fills' includes' nclude some trash debris which. should be selectively separated and removed from the soil prior to re- use as project new fills. Unusual grading problems are not expected in site• earthwork operations. 0 * Site naturalsoils are predominantly sandy non-expansive to very low expansive deposits which work well in compacted fills. Existing fills are locally dày bearing soils which should be selectively buried in deeper fills. Based upon the anticipated grading scheme, and recommendations giveñ'h'erein, finish grade soils are expected to consist of clayey silty sand (SM) with very low expansion potential (El less than 21) Actual classification and expansion characteristic 'of finished grade soil mix can only be 'provided in the final' as-graed compaction report based on appropriate testing. Final foundation and slab subgràde soils should be tested at tl'ie corn ptetión of pad construction and remedial grading to confirm expansion characteristics of bearingsoils which will govern final foundations and slab design. * Groundwater was not encountered within the exploratory excavations completed at the site at the time of our investigation. Based on the available subsurface data, a groundwater condition is not expected to create grading I trenching difficulties or impact future stability of the developed site. * Adequate site surface drainage control is a critical factor in the future stability of the developed property. * Liquefaction and seismically induced settlements will not be a. factor in.the development of the proposed structures and improvements. * Post construction total and differential settlements are not. expected to be a factor in the development of the project site, provided our remedial grading and. foundation recommendations are implemented 'd'uring the constuction phase of the project. ('- VIN3E & MIDDLETON ENGINEERING, INC. 2450 Vrneyard Avenue, Escondido, California 92029-1229. ...Phone (760) ?4'3-114 • Fax (760) 739-0343 GEOTECHNICAL fl/ETIQATIONS QRADINQ SUPERVISION PERTESTINQ ENVIRONMENTAL INVESTIQATION ( PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE '11 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22 2003 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 Fndicated geotechnical conditions at the project site and should be reflected on the final plans and implemented during the construction phase. Added or modified recommendations may also be appropriate and can be provided at the final plan review phase when details of the project development are known: A. Grading and Earthworks Cut! fill and remedial grading techniques maybe used in order to achieve final design grades and improve soil conditions beneath the planned graded lots, structures and improvements. All gradingand 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 C Construction and the 'requirements*' of the following sections wherever applicable: Clearing and Grubbing -'Remove surface vegetation, trash, debris and other unsuitable I deleterious materials from all areas of proposed new fills, improvements, and structures plus 10 feet minimum or as directed in the field. The prepared ground should be inspected and approved by .the project geotechnical engineer or his designated representative Constructib debris generated from the demolition.of the existing site structures and improvements should also be properly removed and disposed of from the site. All irrigation lines should be properly removed from the construction areas. Existing underground utilities in the construction areas should also be pot- holed, identified and marked prior to the actual work. Inactive lines should be properly removed or abandoned as approved. Removals and Remedial Grading - The most effective soil improvement method to mitigate loose to soft compressible upper soils Will utilize removal and.recompaction remedial grading techniques. site upper topsoils, dump fills, weathered sandstone in the areas to receive new fill, structures and improvements plus 10 feet, and the entire section of existing fills. should be removed to the. underlying competent bedrock and plated back as properly compacted fill. The existing eastern fill slope should also be removed and. VTNJE & ?vfIDDLETON ENGINEERING, INC. 2450 MneyaTd Avenue, Escondido, California 92029-1229 • Phone (760) 743-1214 • Fax (760) 739-0343 QEOTECHNICAL rNVFST1QATIONS QRADING SUPERVISION PERC TESTING ENVIRONMENTAL INVFSTIQATION T-1 17 not encountered 30 Lot 8, remove' entire section of existing fills, (approx.) existing fills contain trash debiis T-2, 81/2 not encoUntered 8 Lot 10, remOve entire section 6f existing fills,. backhOe refusal @ 81/2' 1-3 6% not encountered 3 Lot 7 remove entire section of existing fills b'ackhoe refusal @ 6W'. 1-4 31/2 .. • not encountered' . 21/2' Lots 5/6, depth of undercut may. góvern. 1-5 , . 31/2 not encountered 11/2 Lot 3, depth of undercut may govern, refusal. @31/2' El .. -.. PRELIMINARY GEOTECHNICAL INVESTIGATION ' :' PAGE 12 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 reconstructed as a part of the project remedial grading operations in accordance with the requirements of this report. Typical removal depths in the Vicinity of individual exploratory test trench sites are shown in Table 9. The tabulated removal depth's are subject to changes by the project geotechnical consultant in the field at the.timé of grading. Locally. deeper removals may be necessary based on the actual field. exposures and should be anticipated. Removal depths. associated with the large fill section at the east margin of the, property are expected to be. significant and can be estimated from the enclosed Plates 3 and 4 TABLE9 . . . [ . 1-6, J.41/2 . [ not encountered 1½ Lot 3,' depth of undercut may govern ' 4 Notes All 'depths are measured from the existing ground levels. Actual depths may vary at the time of construction based on seasonal conditions and field exposures. Bottom of all removals should be prepared and recompacted as directed in the field. in the parking, roadway and drive lane areas, removals may consist of depths to firm bedrock or. 1-foot below the deepest utility, or 3 feet but not less than 1-foot minimum as directed in the field 5.. Exploratory trenches excavated ,in connection with our study at the indicated locations were backfllled 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 part of the project grading operations:' - . ' .• . ( VI'NJE &'MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue, Escondido, California 92029-1229 • Phone (760) 7.43.1214 • Fax (760) 739-0343 cEOTECHNICAL INVESTIQATIONS ' GRADING SUPERVISION I ' PERC TESTINQ , ENVIRONMENTAL INVESTIqATI ON PRELIMINARY G'EOTECHNICAL INVESTIGATION PAGE 13 (, BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 3. Cut-Fill Transition [Undercuts - Ground transition from excavated cjt to placed fill should not be permitted underneath the proposed structures and improvements. Building foundations and floor slabs should be uniformly supported oh undisturbed cut ground or entirely founded on compactd fills. Transition areas will require special treatment. The cut portion of the dut'/ fill pads Pius 10 feet shOuld' be. undercut to a sufficient depth to provide for a minimum of 3 feet of compacted fill mat below rough finish grades or at least 12 inches of compacted fill beneath the deepest footing whichever is more. In the roadways, driveway, parking and on-grade slabs I improvement transition areas, there should be a minimum of 1-foot of.compacted soils below rough finish subgrade. Undercutting the project cut pads or cut portion of the transition pads will also accommodate excavation of the foundation trenches and underground utilitie in an otherwise cemented Terrace Deposits. In the case of deeper utility " trenches, undercutting to minimum of-6 inches-below the proposed inverts may be considered. ( 4. Fill Materials and Compaction -Soils generated from the excavations ofsite weathered sandstone will predominantly consist of good quality sandy materials which will work well in compacted fills and should be placed at near finish grade levels. Soils generated from the removals of the project exiting fills will include some clay bearing deposits and asphalt I concrete debris. Asphalt I concrete and, other deleterious, material should 'be separated from project fill soils nd removed from the site. As an option,, the concrete fragments may be broken to smaller than 6 inches and included in deeper fills as directed in-the field. The asphalt pieces may also be ground upto minus 3-inch sizes and used as a compacted subbase under the asphalt paving surfaces. Clay bearing soils should be selectively buried in deeper fills at a minimum of 4 feet below rough finish grades. Import soils, if required to complete grading' and achieve final design grades, should be granular non-expansive deposits (expansion index less than-21), tested and approved by the project geotechnical consultant prior to the delivery to the site. Project fills shall -be clean deposits free of vegetation, organic and deleterious maftertrah and debris consisting of minus 6-inch fragments.. Uniform bearing" soil conditions should be constructed at the site by the grading operations.. Site fills should be adequately processed, thoroughly, mixed, moisture conditioned VINJE' & MIDDLETON ENGINEERING, INC. 2450 Mneyard Avenue; Escondido, California 92029-1229 Phone (760) 743-1214 • Fax (760) 739-0343 QEOTECRNICAIJ'TNVPSTIQATXONS '. GRADING SUPERVISION PERC TESTING ' ' ENVIRONMENTAL INVEST1QATI0N. PRELIMINARY.GEOTECHNICAL INVESTIGATION PAGE 14 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 to near optimum moisture levels as directed in the field, placed in thin uniform horizontal lifts and mechanically, compacted to a minimum of 90% of the corresponding laboratory maximum dry density perthe ASTM D-1 557, unless otherwise specified. 5. Permanent Graded Slopes - Major new graded cut / fill slbpes are not anticipated in connection with the site development. However, the existing eastern fill slope should be removed and reconstructed as a part of the project grading operations as .. recommended herein. The reconstructed . fill embankments should be programmed for 2:1 gradients maximum. The new fill slope shall be provided with a lower Keyway. The Keyway shOuld maintain a minimum depth of 2 feet into competent sandstone units with a minimum width of 15 feet as approved by the project geo.technical engineer or his designated field representative. The Keyway should expose competent sandstone throughoUt..vith the bottom.-heeled back a minimum of 2% into the.... natural hillside. Additional level benches shOuld be constructed into the natural hillside as the fill slope construction progresses. Fill slopes should also be compacted to 90% (minimum) of the laboratory standard out to the.slope'fac. Over-building and cuffing back to the compacted core, or backrolling at a maximum of 4-foot vertical increments and "track-Walking" at the completion of grading, is recommended for site fillS slope construction. Geotechnical engineering inspections and testing will be necessary to confirm adequate compaction levels within the fill slope face. Graded slopes greater than 30 feet and less than 60 feet in vertical height should be provided with a minimum of 6 feet wide terrace(s) to control surface drainage and debris. The specified terrace(s) should be provided at 30 feet vertical intervals except where only One terrace is required, it should be placed near the slope mid-height. Cut slopes, if any planned at the site, should also be planned for 2:1 gradients and inspected and approved by the project geotechnical consultant during the grading to confirm stability. Additional recommendations will be provided at that time based the actual field exposures, if necessary. 6. Shrinkage and Bulking - Based upon our analyses, on-site existing fills and topsoil deposits may be expected to shrink approximately 5% to 15%, and the soils generated from the excavations of the On-site sandstone bedrock may be anticipated to bulk nearly the same amount on a volume basis when compacted to at least 90% of the corresponding maximum density. VINJE &'MIDDLETON ENGINEERING. INC. 2450 Vineyard Avenue, Escondido, California 92029-1229 • Phone (760)' 743-1214 • Fax (760) 739-0343' QEOTECHNICAL ThVESTIQATIONS . QRADINQ SUPERVISION PERC TESTINQ ENVIRONMENTAL JNVESTIQATION ( ( 1 PRELIMINARY G'EOTECHNICAL INVESTIGATION PAGE 15 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 200.3 Surface Drainage and Erosion Control -A critical element to the continued stability of the 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 project civil engineer design. * 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. Area drains should be installed. * The finished slope should be planted soon after completion of grading. Unprotected slope faces will be subject to' severe erosion and should not be' all Over-watering of the slope faces should also not be allowed. Only the'amout'of water to sustain vegetation- should be poVided * Temporary erosion control facilities and silt fences should be installed during ( . . . the construction phase periods, and until landscaping is fully established as indicated and specified on the approved project grading I erosion plans Engineering. Inspections - All grading operations including removals, suitability of earth deposits used as compacted fill, and compaction procedures should be continuously inspected and tested by the project ge'otechnical consultant and presented in the final as-graded compaction report. The nature of finish subgrade soils should also be confirmed in the final compaction report' at the completion of grading: Geotechnical engineering' inspections shall include, but not limited to the following: * Initial Inspection - After the grading I brushing limits have been staked, but before grading I brushing starts. * Keyway I bottom of over-excavation inspection - After the bottom of over- excavation 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. VZNJE & M'IDDLETON ENGINEERING- INC. 2450 Vbieyard Avenue, Escondido, California 92029-1229 • Phone (760) 743-1214 S Fax (760) 7'39-O343' QEOTECHNICAL INVESTIGATIONS ' GRADING SUPERVISION PERC TESTING ENVIRONMENTAL INVESTIGATION PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 16 BLACK. RAIL ROAD, CARLSBAD, CALIFORNIA : MAY 22, 2003 Fill I wall backfill inspection - After the fill I wall backfill placement is started, but before the vertical height of fill I backfill exceeds 2 feet. A minimum of one test shall be required for each 100 lineal feet maximum with the exception of wall baOkfills 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 shalt be required regardless of fill thickness. * Foundation trench inspection - After the foundation trench excavations, but before steel placement. * Foundation bearing 1 slab subgrade soils inspection - Within 72 hours prior to the placement of concrete for proper moisture and specified compaction levels: . . * Geotechnical foundation / slab steel inspection After the. steel placement is completed, but 24 hours before the scheduled concrete pour. * Subdrain / wall back drain inspection Afterthe trench excavations; but during the actual placement. All material shall conform to the project material specifications and approved by the project eotechnical engineer. * . Underground utility I plumbing. trench inspection - After the trench excavations, but before installation of the underground facilities. Local and CAL-OSHA safety requirements for open exôavations apply. Inspection of the pipe bedding may also be required bythé project geotechnical engineer. * Underground utility I 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 & MIDDLETON ENGINEERING, INC. 2450 Vrneyard Avenue, Escondido, California 92029-1229 • Phone (760) 743-1214 • Fax (760) 739-0343 QEOTECHNICAL INVESTIGATIONS GRAWNq SUPERVISION PERC TESTING • ENVIRONMENTAL INVESTIGATION PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 17' BLACK RAIL ROAD, CARLSBAD, CALIFORNIA ' ' MAY 22, 203 * Pavement I 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 Interior Floor Slabs The following preliminary recommendations are consistent with very low expansive (El less than 21) silty sand (SM) fdundation bearing soil. Final foundation and slab design will depend on expansion characteristics of finish grade soils and the. actual' fill differential thickness Underneath the proposed buildings. All recommendations should be confirmed and I or revised as necessary in the rough grading compaction report based on site as-graded geotechnical conditions and actual testing of the foundation bearing earth materials. Individual building sites may require specific foundation I slab design and may be anticipated. Additional specific recommendations may also be necessary and should be given at the time of' 'the plan review phase when detailed grading and structural' I. architectural'' drawings are available: Continuous strip and perimeter foundations should be sized at least 12 inches wide and '12 inches deep for single-story, and 15 inches wide and 18 inches deep for two-story structures. Isolated 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 beneath floor slabs. Exterior continuous footings should enclose the entire building perimeter. 2. Continuous interior and exterior foundations should be reinforced by'at least 2- #4 reinforcing bars. Place a minimum of 144 bar 3 inches, above the bottom of the footing and a minimum of 144 bar 3 inches below the top of the footing. Reinforcement details for spread pad footings should be provided by the project architect I structural engineer. 3. All interior slabs should be a minimum of 4 inches in thickness, reinforced with #3 reinforcing bars spaced 18 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 6-mil plastic moisture barrier placed mid-height in the sand. In the case of good quality sandy-subgrade soils, as approved by the project geotechnical engineer, the 6-mil plastic moisture barrier may be laid directly over the slab subgrade and covered with a minimum of 2 inches of clean sand (SE 30 or greater); V1NJE & MIDDLETON ENQINEERINQ, INC. 2450 Vrneyard Avenue, 'Escondido, California 920291229 • Phone (760) 743-1214 • Fax ('760) 739-6343 QEOTEC1iNICAfINVEST1QATXONS GRADING SUPERVISION ' PERC TESTING ENVIRONMENTAL INVESTIQATION ( PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 18 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 Provide "softcut" contraction / control joints consisting of sawcuts spaced 10 feet on center maximum each way for all interior slabs. 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 sawcuts should be a minimum of 1-inch in-depth but not to exceed 1%-inches in depth maximum. 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. Provide re-entrant corner reinforcement for all interior slabs. Reeritrant corners will depend on slab geometry and I or interior column locations. The enclosed Plate 9 may be used as a general guideline. 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 within 7. hours prior to the placement of concrete. ( C. Exteriär Concrete Slabs I FIaorks, All exterior slabs (walkways, and patios) should be a minimum of 4 inches in thickness reinforced with 6x6/10x10 welded wire mesh carefully placed at mid- height in the slab. Provide "tool joint" or "softcut" contraction / control joints spaced. 10 feet on centers (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 finalfinish 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 1A-inches deep maximum. In case of softcut joints, anti- ravel skid plates should be.used and replaced with each blade to avoid spIIing and raveling. Avoid wheeled equipments across cuts for at least 24 hours. All exterior slab designs should be confirmed in the final as-graded compaction report. 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. VNJE &.MIDDLETON ENGINEERING, INC. 2450 Vineyard Avenue, Escondido, California 92029-1229 • Phone (760) 743-1214 • Fax (760) 739-0343 QEOTECHNICALINVESTIQATIONS GRADING SUPERVISION PERC TESTING ENVIRONMENTAL INVESTIQATION. ( PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 19 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY22. 2003 a. Soil Design Parameters The following preliminary soil design parameters are based on the 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: * Design wet density of soil = 124.9 pcf. * Design angle of internal friction of soil = 31 degrees. * Design active soil pressure for retaining structures =40 pcf (EFP), level backfill, cantilever, unrestrained walls. * Desin at-rest soil pressure for retaining structures = 59 pcf (EFP),. nom yielding, restrained walls. * Design passive soil pressure for retainihg structures = 399 pcf (EFP), level surface at the toe. * Design coefficient of friction for concrete on soils = 0.38. * Net allowable fOundatipn pressure for on-site compacted fills (minimum 12 inches wide by 12 inches deep footings) = 1500 psf. ( * Allowable lateral bearing pressure (all structures- except retaining walls) for 'on- site compacted fill = 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 safety factor of 2 may be considered for sliding stability where sensitive structures and improvements are planned near or On top of retaining walls. * When combining passive pressure and. frictional resistance the passive component should be reduced by one-third. The net allowable foundation pressure provided herein was determined for footings having a minimum width and depth of 12 inches. The indicated value may be increased by 20% for each additional foot of depth and 20% for each additional foot of width to a maximum of 4000 psf if needed. The allowable foundation pressure provided herein also applies to dead plus live loads and may be increased by one-third for wind and seismic loading. * The allowable lateral bearing earth pressures may be increased by the amount I of the designated value for each additional foot of depth to a maximum of 1500 pounds per square foot. VINJE & MIT DLETON ENGINEERING, INC. 2450 Vineyara Avenuej Escondido, California 92029-1229 • Phone 'C60) 743-1214 • Fax (760) 739-0343 qEOTECHNIcA1;-INVESTIQAT1ONS GPADINC3 SUPERVISION , PERC TESTINQ " ' ENWRONMENTAL INVEErI0AT1ON ( PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 20 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 E. Asphalt and PCC Pavement Desiq.n Specific pavement designs can best be provided at the completion of rough grading based on 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 asphalt on 6 inches Caltrans Class 2 aggregate base may be considered for the on-site asphalt paving surfaces. Actual design will also depend on the design TI and approval of the City of Carlsbad. Base materials should be compacted to a minimum of 956/6 of the corresponding maximum dry density (ASTM D-1557). Subgrade soils beneath the asphalt paving surfaces should also be compacted to a minimum of 95% of the corresponding maximum dry density within the upper 12 inches. Residential PCC driveways and parking supported on noh-expànsiVe to very low expansive (El less than 21) granular subgrade soils should be a minimum ( of 5 inches in thickness, reinforced with #3 reinforcing bars at 18 inches on centers each way, placed mid-height in the slab. Subgrade soils beneath the PCC driveways and, parking should be compacted to a minimum of 90% of the corresponding maximum dry density. Provide "tool joint" or "softcut" contractiOn Lco.ntrol 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 - l5o'psi to 800 psi. Tool or softcuts should be aminimum of 1-inch but should not exceed 1 %-inchOs deep maximum. In case of softcut joints, anti- ravel skid plates should be used and replaced with each blade to avoid spàlling and raveling. Avoid wheeled equipments across cuts for at least 24 hours. Subgrade and basegrade SQIIS should be tested for proper moisture and the specified compaction levels and approved by the project gebtechnical consultant within 72 hours prior to the 'placement of the base or asphalt.! PCC finish surface. 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 VrNJE &MIDDLETON ENQINEERINQ, INC. 2450 Vineyard Avénü, Escondido, California 92029-1229 • 'Phone (760) 743-1214 -'Fax (760)739-0343 QEOTECHNICA 1N%TETZQAT1ONS ' QRADINQ SUPERVISION- PERC TESTING ENVIkONMENTAL INVESTIGATION ( PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 21 (.. BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 within the public right-of-way should have 12 inches subgrade compacted to a minimum 95% compaction levels, and provided with a 95% compacted Class 2 base section per the structural section design. Base section may not be required under curb and gutters, and sidewalks in the case of nonexpansive subgrade soils (expansion index less than 21). Appropriate recommendations should be given in the final as-graded compaction report. F. General Recommendations The minimum foundation design and steel reinforcement provided herein are based on soil characteristics and are not intended to be in lieu of reinforcement necessary for structural considerations. All recommendations should be further evaluated in the Site specific study for each individual lot and confirmed by the project architect I structural engineer. 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 geote.chnical engineering services. Inadequate staking and I or lack of grading control. may result in unnecessary additional grading which will increase, construction costs. Footings Iodated on or adjacent to the top Of slopes should 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. 4.. Expansive clayey soils should not be used for backfihling 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: Retaining walls should be, provided with a back drainage in general accordance with the attached Plate 10. 5. . All underground utility and plumbing trenches should be compacted to a minimum of 90% of the maximum dry density of the soil unless otherwise specified. 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. VITNJE & MIDDLETON ENGINEERING, INC 2450 Vineyard Avenue Escondido, California 92029-1229 Phone (760) 743-1214 • Fax (760) 739-0343 qEomcn?rc4u nsTfQArzoNs GRADING SUPERVISION PE'RC TESTINQ ENVIRONMENTAL NVESTIQATION PRELIMINARY GEOTECHNICAL INVESTIGATION. PAGE 22 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22'Y 2003 6. Site drainage over the finished pd. surfaces 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. Roof lines 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. tConsiderations 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. .. 7: Based upon the results of the tested soil sample, the amount of water soluble: • sulfate (SO4) in the soil was found to be 0.019 percent by weight which is considered negligible according to the CalifOrnia BUilding Code Table No. 19-A- -. Portland cement Type I or II may be used. .. 8. The following are appropriate based on the Ph-Resistivity test esult: . . ' TABLE 1O • I T-1 ' Years to Perforation of Steel Culverts. 19 I 24 30 I 41 53 1.64 1 9 Final plans should reflect preliminary recommendations given in this report Final foundations and grading plans may also be reviewed by the project geotechnical consulthnt for conformance with the requirements of the geotechnical investigation report outlined herein More specific recommendations may be hecessary and should be given when final grading.. and architectural /,structural drawings are available 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 geotechnicál consultant.. ' . . .. • The amount of shrinkage and related cracks that occurs in the concrete slab-on-grades, flatworks and driveways depend on many factors the most important of which is the amount of water in the. 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 minirnum the following should be considered:' ,• . . - , • - -.. - . • - - : . •, -• $ . VINJE & MIDDLETON ENGINEERING, INC 2450 Mneyard Avenue, Escondidó, California 920294229 • Phone (760) 743-1214 • Fax (760) 739-0343 QE0TECHNICAL1NVT1QATI0NS . QRADINQSUPERWSION PERC TEsrmJQ • ENVIRONMENTAL INVESTIGATION PRELIMINARY GEOTECHNICAL INVESTIGATION :' PAGE 23 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA '' MAY 22, 2003 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 lbs more (nearly 5 gal.) water per cubic yard than concrete with"l -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. 12. 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 pertinent reports and plans, subsurface exploratory excavations as well as ourexperience 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 hOld"responsible for changes to the physical conditions of the property such as-addition Of fiul'soils, added cut slopes, or changing drainage patterns which occur without our inspection or control: VTNJE & MIDDLETON ENGINEERING, INC 2450 Vineyard Avenue Escondido California 92029-1220 Phone (760) 743 1214 Fax (760) 739-0343 GEOTECHNICAE INVESTIQAIIONS QRADINQ SUPERVISION PERC TESTING ' ' 'ENVIRONMENTAL INVESTIGATION I ii (. PRELIMINARY GEOTECHNICAL INVESTIGATION PAGE 24 BLACK RAIL ROAD, CARLSBAD, CALIFORNIA MAY 22, 2003 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 1/s-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 warrant'! 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 #03-236-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 RTJFE ( (' .CE cgo ) * * CEG #980 ENGNEERJNC, S. Mehdi S. Shariat E #46174 No. 4674 Exp. 12-31-06 4-Q ba Steven JMelzer L) RG#6953 S4AYQ ( DMISMSS/SJM/jt Distribution: Addressee (5) * 693 ) * 9. EJZp.cJ3//o - M-' VINJE & MIDDLETON ENGINEERING, INC. 2450 VineyaTd Avenue, Esc ' ornia 92029-1229 • Phone (760) 743-1214 • Fax (760) 739-0343 çEOTECHNICAL INVESTIGATIONS GRADING SUPERVISION PERC TESTINq • • ENVIRONMENTAL INVESTIGATION'