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HomeMy WebLinkAboutCDP 15-17A; 6125 PASEO DEL NORTE; GEOTECHNICAL INVESTIGATION; 2015-02-10. , Geotechnical Investigation Second Floor Addition and New Parking Improvements 6125 Paseo Del Norte Carlsbad, California February 10, 2015 Prepared For: BSD Builders, Inc. Mr. Jeff Blair 8825 Rehco Road, Suite A San Diego, California 92121 Prepared By: SMS Geotechnical Solutions, Inc. 1645 South Rancho Santa Fe Road, Suite 208 San Marcos, California 92078 Project No. GI-12-14-34 February 10, 2015 BSD Builders, Inc. Mr. Jeff Blair 8825 Rehco Road, Suite A San Diego, California 92121 SMS GEOTECHNICAL SOLUTIONS, INC. Consulting Geotechnical Engineers & Geologists 1645 S. Rancho Santa Fe Rd., Suite 208 San Marcos, California 92078 Telephone: 760-761-0799 smsgeosol. inc@gmail.com GEOTECHNICAL INVESTIGATION, SECOND FLOOR ADDITION AND NEW PARKING IMPROVEMENTS, 6125 PASEO DEL NORTE, CARLSBAD, CALIFORNIA In accordance with your request, SMS Geotechnical Solutions, Inc., has completed the attached Geotechnical Investigation Report for the planned second floor addition to the existing commercial/industrial building at the above referenced property and new parking improvements on the adjacent southern vacant parcel. We understand that both parcels will be combined for the purpose of the planned new development. The following report summarizes the results of our review of available pertinent documents and reports, subsurface exploratory test excavations, sampling, laboratory testing, engineering analysis and provides conclusions and recommendations for the proposed new additions and improvements, as understood. From a geotechnical engineering standpoint, it is our opinion that the project property and adjacent southern parcel are suitable for the planned second floor addition and parking 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 indicated 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 Project No. GI-12-14-34 will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. SMS Geotechnica/ Solutions, Inc. S. Mehdi S. Shariat GE #2885 GEOTECHNICAL INVESTIGATION SECOND FLOOR ADDITION AND NEW PARKING IMPROVEMENTS 6125 PASEO DEL NORTE CARLSBAD, CALIFORNIA I. INTRODUCTION Project properties investigated herein consist of a relatively level graded northern pad occupied by an existing commercial/industrial type building with associated improvements, and an adjacent vacant lot to the south that gives way to a descending artificial slope that continues to a lower, natural flowline and open space terrain below. The study properties are located on the west side of Paseo Del Norte, east of Interstate 5 in the coastal areas of the City of Carlsbad. Project study site(s) location is shown on a Vicinity Map attached to this report as Plate 1. The approximate site coordinates are 33 .1178EN latitude and -117.3184EW longitude. The existing building supported on the northern level pad is currently vacant. The building was most recently used as a commercial warehouse operation (White Cap). We understand that expansion of the existing building is planned, and will consist of adding a new second floor addition. The southerly parcels will be annexed to the northern property in order to add new parking improvements. Re-development and new improvements are expected to consist of regrading the existing building perimeter parking areas. Regrading will include terracing and stabilization of the southerly descending artificial slope, and possibly new retaining walls for ground transitioning over the slope in connection with the new parking improvements. The purpose of this investigation was to determine the underlying soil and geotechnical conditions at the existing building location and southern vacant property, and evaluate their influence upon the proposed second floor building addition and new parking improvements. Technical report review, slab coring, exploratory test trenching and drilling, in-situ testing and sampling, and laboratory testing were among the activities conducted in conjunction with this effort which resulted in the geotechnical development and foundation recommendations presented herein. The scope of this report is limited to those areas planned for the new second floor building addition and parking improvements as specifically delineated in this report. Other areas of the project site and existing structures/improvements not investigated, are beyond the scope of this report. II. SITE DESCRIPTION A Geotechnical Map delineating the project ex1stmg conditions and proposed development, reproduced from the Preliminary Parking Expansion Plan prepared by Hofman Planning & Engineering (dated December 12, 2014), is included as Plate 2. As shown, the project site consists of three contiguous parcels: a northerly developed lot; a central vacant undeveloped parcel; and southerly natural flowline open space terrain. The northerly developed parcel is a graded pad currently supporting an existing commercial/industrial tilt-up type building with associated paving improvements along the northern and western perimeter. A 2: 1 (horizontal to vertical) graded slope, on the order of 10 feet in maximum vertical height, marks the eastern perimeter. Engineering records and documentation pertaining to the original building pad development and building construction are not available for review. Based on our observations, a tilt-up panel joint is separating in the southeastern portion of the building, with daylight visible from inside the building at this location. The noted separation may be the result of local compression (settlement) of the underlying fill deposits perhaps in response to inadequate perimeter drainage conditions in that area. Building concrete floor slabs have also experienced numerous continuous cracks ranging to approximately ¼ to ½-inch wide maximum with local vertical offsets, mostly occurring near the perimeter walls. Upper, level portions of the adjacent southern parcel are marked by numerous old stockpiled dump fills which have been disfigured by severe erosion. Local cavities are present among the dump piles which are thought to be the result of"piping" and washouts which then outflows on the slope face. The irregular dump fill surfaces give way to a graded slope which descends approximately 20 feet to a natural east-west trending drainage course below. The slope face is highly irregular due to "piping," washouts, and erosional features with overall 2: 1 gradients. Deep erosional gullies, shallow slump scarps, and surficial mud-flows have deposited sediments along the toe of slope and north margin of the drainage course, and have resulted in the irregular slope gradients which locally approach 1 ½: 1. Drainage within the northern lot is generally developed and sheetflows over the improved surfaces onto Paseo Del Norte. It appears, however, that the building roof runoff may have been ponding near the foundation on the east side of the commercial building, where above ground tight pipes have been installed for proper capturing and discharging water away from the building foundation. Drainage at the southern vacant parcel with irregular surfaces is very poor to nonexistent, and has caused severe erosion, "piping," washouts, and sediment transports. Numerous ground depressions created by the soil stockpiles appear to pool storm water with subsequent "piping" through the loose stockpiled soil causing large cavities. Overflow of concentrated surface runoff and washouts have also occurred significantly impacting the slope face with erosional scarps and mud-flow type surficial slope failures. III.PROPOSED DEVELOPMENT Planned expansion of the existing building in the northern parcel will consist of a new second floor addition. The adjacent southern property will be annexed to the northern parcel to create a larger pad for planned new parking improvements. Minor grade alterations will be needed to Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page3 achieve new parking improvement grades. The creation of large new graded slopes is not planned. New foundations and architectural plans for the planned interior building modifications and second floor addition are not yet finalized. However, we understand that the planned second floor addition will be supported on a new independent foundation system. Associated construction is anticipated to consist of related interior tenant and underground improvements, repairs and/or replacement of the cracked interior floor slabs, and possible retrofitting of the existing building foundations. Some regrading of the existing perimeter parking improvements is also proposed. The proposed site redevelopment and parking expansion are depicted on the enclosed Plate 2. As, shown, the adjacent southern parcel will be re-graded as a part of the project new parking expansion pad development. New transition retaining walls over the slope are anticipated to establish the design parking improvement pad grades. Associated improvements are also anticipated to consist ofreconstruction and stabilization of the descending southerly slope, including appropriate vegetation cover and installation of erosion control facilities in order to create a stable parking expansion pad above, and the protection of the natural drainage course below. IV. FIELD INVESTIGATION Subsurface conditions at the study areas were chiefly determined by field mapping the existing surface exposures and the excavation of three exploratory bonngs and six test pits. The exploratory borings were drilled inside the building through 12-inch diameter, pre-cut slab cores. Exploratory borings were advanced into the underlying soil utilizing a truck-mounted, 8-inch diameter, hollow stem auger drill rig. Test pits were excavated at selected locations within the adjacent southern parcel using a tractor-mounted backhoe. All the exploratory borings and test pits were logged by our project geologist and engineer who also retained representative soil samples at selected locations and intervals for subsequent laboratory testing. Exploratory borings were backfilled and slab cores patched with ct-inch ready mix concrete upon completion of our work. The test pits were also loosely backfilled. Exploratory Boring and Test Pit locations are shown on the enclosed Geotechnical Map, Plate 2. Logs of the borings and test pits are included as Plates 3 through 11. Laboratory test results and engineering properties of selected samples are summarized in following sections. V. GEOTECHNICAL CONDITIONS Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page4 The project site is characterized by a northern developed graded pad and adjacent irregular terrain to the south which gives way to a descending graded slope that terminates at a natural flowline. The study locations are underlain by stable Terrace Deposits (Qt) and formational rocks (Tsa) mantled by alluvial soils associated with the nearby drainage course and artificial fill deposits. Erosional scarps and mud-flow type surficial failures are currently impacting the irregular descending graded slope. However, large scale deep-seated instability which could preclude the planned construction of new parking improvements is not in evidence. Geologic Cross-Sections depicting subsurface conditions and planned finish grades are included as Plates 13 and 14. The following earth materials are recognized: A. Earth Materials Formational Rock (Tsa): Eocene age formational rocks, more commonly designated as the Santiago Formation, were exposed in Test Pit 2 (TP-2) beneath alluvial soils. The rocks consist of light grey colored siltstone-sandstone deposits that were found in blocky and dense conditions overall. The formational rocks are stable deposits that likely occur at depth beneath the upper site Terrace Deposits and alluvium. Terrace Deposits (Qt): Pleistocene age Terrace Deposits, typical of local coastal areas, mantle the underlying formational rocks. As exposed, the Terrace Deposits typically consist of dark-colored sandstone that was found ranging from weathered friable in upper exposures becoming cemented and dense to very dense at shallow depths. Project Terrace Deposits are competent deposits that will adequately support new fills, structures, and improvements. Alluvial Deposits (Qal): Alluvial soils, associated with the nearby natural drainage course, are present within the lower open space flowline and along the drainage course margin. As encountered in our exploratory excavations, the alluvium typically consists of silty to clayey sand deposits that occur in moist and medium dense to dense conditions overall. Project dense alluvium will provide adequate support for new fills, structures, and improvements. Compacted Fills (Cat): Compacted fill deposits underlie the existing building pad surfaces at the northen parcel. The fills were placed during the original building pad development which utilized conventional cut-fill grading techniques. Compacted fills were placed over the majority of the site to create the existing pad grades. Cut ground is thought to occur in the north/northwestern margins of the pad. Compacted fills are estimated to be on the order of 5 to 6 feet thick underneath the existing building areas. Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 5 Records of engineering observation and compaction testing during the original pad grading and fill placement are not available for review. Site existing compacted fills (map symbol Caf) fills typically consist of clayey to silty sand deposits found in moist and dense to tight conditions overall. Approximate distributions of compacted fills at the project building pad are shown on the enclosed Plates 2 and 14. Dump Fills (Uaf): Dump fill/stockpiled soil (map symbol Uaf) cover most of the surface areas of the adjacent vacant parcel planned for new parking improvements as well as the southern margin slope face. Dump fills consist oflight-brown loose to very loose, mostly poorly-graded, medium grained silty to clayey sand. The dump fills occur in stockpiles on the upper surface areas and as irregular surfaces impacted by severe erosion and washout cavities on the descending slope face. Approximate distribution of the dump fills at the project site are shown on the enclosed Plates 2, 13, and 14. Details of project earth deposits are given on the enclosed Boring and Test Pit Logs, Plates 3 through 11. Laboratory test results and engineering properties of selected soil types are summarized in following sections. B. Groundwater and Surface Drainage Groundwater conditions were not encountered in project exploratory borings and test pits to the depths explored at the time of our field investigation and are not expected to impact the planned new building additions and parking expansion. However, site drainage in the adjacent southern parcel and descending slope is very poor to nonexistent, and has caused severe erosion, "piping," washouts, and sediment transports. Soil stockpiles have created numerous ground depressions causing pooling of storm water with subsequent "piping" through the very loose sandy stockpiles soil causing large cavities. Overflow of concentrated surface run off and washouts have caused large erosional scarps and surficial mud-flow type failure of the dump fill-covered slope face. Like all developed graded sites, the proper control of surface drainage is an important factor in the continued stability of the property and adjacent slope. Ponding or pooling of surface drainage or concentrated flow conditions should not be allowed, and over- watering of site vegetation should be avoided. The dump fill covered and eroded southerly descending slope should be reconstructed, stabilized, and planted with a proper vegetation cover. Stormwater runoff and erosion control facilities should also be constructed, as necessary and appropriate. Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California C. Slope Stability February 10, 2015 Page6 Significant ground modifications or the creation of new large graded slopes are not proposed in connection with the proposed site redevelopment and parking expansion. The eroded southern graded slope is also underlain by competent sandstone Terrace Deposits underneath the slope face dump fill cover impacted by surficial failure scarps and erosional soil debris. Large scale or massive deep-seated slope failure conditions are not in evidence within the exposed natural Terrace Deposits or alluvium. However, poorly graded cohesionless Terrace Deposit sands are more prone to erosion in steeper slope conditions where impacted by poor surface drainage and uncontrolled concentrated flow conditions. Based on our study and site observations, the southern graded slope gradients are very irregular largely approaching 2: 1 with locally 1 ½: 1 or steeper gradients where impacted by severe surficial failure conditions. Noted slope failures are shallow surficial erosional and mud-flow type features consisting of slumping of the slope face very loose dump fill material within the outer few feet that had become overly saturated or subjected to concentrated flow and out-of-slope seepage conditions. Out-of-slope seepage conditions have also cause washouts and local cavities within the slope. Slope stabilization procedures which include removal of all erosional cavities, erosional features (scarps), and mud-flow debris should be considered as recommended in the following sections. Site slope stabilization should also include adequate drainage improvements by collecting and redirecting surface water away from the top of slope, installation of stormwater control facilities and proper protective vegetation cover. 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 ( 1934-197 4 ), 3 7 earthquakes were recorded in San Diego coastal areas by the California Institute of Technology. None of the recorded events exceeded a Richter magnitude of3.7, nor did any of the earthquakes generate more than modest ground shaking or significant damages. Most of the recorded events occurred along various offshore faults which characteristically generate modest earthquakes. Historically, the most significant earthquake events which affect local areas originate along well known, distant fault zones to the east and the Coronado Bank Fault to the west. Based upon available seismic data, compiled from California Earthquake Catalogs, the most significant historical event in the area of the study site occurred in 1800 at an Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 7 estimated distance of 8 miles from the project area. This event, which is thought to have occurred along an offshore fault, reached an estimated magnitude of 6. 5 with estimated bedrock acceleration values of 0.0148g at the project site. The following list represents the most significant faults which commonly impact the region. Estimated ground acceleration data compiled from Digitized California Faults (Computer Program EQFAULT VERSION 3.00 updated) typically associated with the fault is also tabulated. TABLE 1 MAXIMUM FAULT ZONE DISTANCE FROM SITE PROBABLE ACCELERATION (R.H.) Rose Canyon Fault 4.0 Miles 0.272g Newport-Inglewood Fault 7.0 Miles 0.203g Coronado Bank Faull 20.0Miles 0.192g Elsinore-Julian Fault 25.2 Miles 0. 138g The locations of significant faults and earthquake events relative to the study site are depicted on a Fault -Epicenter Map attached to this report as Plate 12. More recently, the number of seismic events which affect the region appears to have heightened somewhat. Nearly 40 earthquakes of magnitude 3.5 or higher have been recorded in coastal regions between January 1984 and August 1986. Most of the earthquakes are thought to have been generated along offshore faults. For the most part, the recorded events remain moderate shocks which typically·resulted in low levels of ground shaking to local areas. A notable exception to this pattern was recorded on July 13 , 1986. An earthquake of magnitude 5.3 shook county coastal areas with moderate to locally heavy ground shaking resulting in $700,000 in damages, one death, and injuries to 30 people. The quake occurred along an offshore fault located nearly 30 miles southwest of Oceanside. A series of notable events shook county areas with a (maximum) magnitude 7.4 shock in the early morning of June 28, 1992. These quakes originated along related segments of the San Andreas Fault approximately 90 miles to the north. Locally high levels of ground Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 8 shaking over an extended period of time resulted; however, significant damages to local structures were not reported. The increase in earthquake frequency in the region remains a subject of speculation among geologists; however, based upon empirical information and the recorded seismic history of county areas, the 1986 and 1992 events are thought to represent the highest levels of ground shaking which can be expected at the study site as a result of seismic activity. • In recent years, the Rose Canyon Fault has received added attention from geologists. The fault is a significant structural feature in metropolitan San Diego which includes a series of parallel breaks trending southward from La Jolla Cove through San Diego Bay toward the Mexican border. Test trenching along the fault in Rose Canyon indicated that at that location the fault was last active 6,000 to 9,000 years ago. More recent work suggests that segments of the fault are younger having been last active 1000 -2000 years ago. Consequently, the fault has been classified as active and included within an Alquist- Priolo Special Studies Zone established by the State of California. Fault zones tabulated in the preceding table are considered most likely to impact the region of the study site during the lifetime of the project. The faults are periodically active and capable of generating moderate to locally high levels of ground shaking at the site. Ground separation as a result of seismic activity is not expected at the property. E. Seismic Ground Motion Values Seismic ground motion values were determined as part of this investigation in accordance with Chapter 16, Section 1613 of the 2013 California Building Code (CBC) and ASCE 7-10 Standard using the web-based United States Geological Survey (USGS) ground motion calculator. Generated results including the Mapped (Ss, S1), Risk- Targeted Maximum Considered Earthquake (MCER) adjusted for site Class effects (SMs, SM1) and Design (Sos, Sm) Spectral Acceleration Parameters as well as Site Coefficients (Fa, Fv) for short periods (0.20 second) and I-second period, Site Class, Design and Risk- Targeted Maximum Considered Earthquake (MCER) Response Spectrums, Mapped Maximum Considered Geometric Mean (MCEa) Peak Ground Acceleration adjusted for Site Class effects (PGAM) and Seismic Design Category based on Risk Category and the severity of the design earthquake ground motion at the site are summarized in the enclosed Appendix. F. Geologic Hazards Geologic hazards are not presently indicated at the project site. The existing southern margins graded slope impacted by dump soils and uncontrolled runoff is recommended for regrading and stabilization as apart of the project parking expansion improvements. 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 Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California rupture failures are not anticipated. G. Field and Laboratory Tests and Test Results February 10, 2015 Page 9 Earth deposits encountered in our exploratory test excavations were closely examined and sampled for laboratory testing. Based upon our subsurface exposures, site soils have been grouped into the following soil types : TABLE2 Soil Type Description 1 Tan brown silty to clayey fine sand (Fill/ Alluvium) 2 Red brown -brown silty fine to medium sand w/trace clay (Terrace Deposits) 3 Light grey siltstone-claystone (Formational Rock) The following tests were conducted in support of this investigation: 1. Standard Penetration Tests: Standard penetration tests (SPT) were performed at the time of bore hole drilling in accordance with the ASTM standard procedure D- 1586, using rope and Cathead. The procedure consisted of a standard 51 MM outside diameter sampler, 457 MM in length and 35 MM in inside diameter using 5-fciot long AW drill rods driven with a 140-pound hammer dropped 30 inches. The bore hole was 200 MM (8 inches) in diameter and drill fluid or water was not required for bore hole support. The test results are indicated at the corresponding locations on the enclosed Boring Logs, Plates 3 through 5. 2. Grain Size Analysis: Grain size analyses were performed on representative samples of Soil Type 1. The test results are presented in Table 3. TABLE3 Sieve Size ¾" ½" ##4 #10 #20 #40 #200 Location Soil Type Percent Passing B-1 @ 5' 1 100 100 100 100 99 91 43 B-1 @ 20' I 100 100 100 100 99 93 43 - Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 10 3. Maximum Dry Density and Optimum Moisture Content: The maximum dry density and optimum moisture content of Soil Types 1 and 3 were determined in .accordance with ASTM D-1557. The results are presented in Table 4. TABLE4 Location Soil Maximum Dry Optimum Moisture Type Density (Km-pcf) Content (Topt-%) B-3 @ 2½' 1 129 9 TP-1 @ 3' 2 123.5 11 4. Moisture-Density Tests (Undisturbed Ring & Chunk Samples): In-place dry density and moisture content of representative soil deposits beneath the site were determined.from relatively undisturbed ring and chunk samples using the weights and measurements, and water displacement test methods, respectively. Test results are presented in Table 5 and tabulated on the attached Boring and Test Pit Logs. TABLES Field Field Dry Mu.Dry In-Place Deglff Soil Moisture Relative of Sample Location Type Content Density Density Compaction Saturation (T-%) (Kd-pcf) (Km-pcf) (%) (S%) B-1 @ 2' (Building) 1 9 117.5 129 91 60 B-1 @ 8' (Building) I 14 113.2 129 88 81 B-1 @ 15' (Building) 2 13 112.7 129 91 73 B-2 @ 3' (Building) 1 10 118.9 129 92 68 B-2 @ 6' (Building) 2 12 114.8 123 .5 93 72 B-2 @ 15' (Building) 2 13 118.8 123 .5 96 88 B-3 @ 2½' (Building) I 11 117.3 129 91 73 B-3 @ 5½' (Building) 2 14 116.6 123.5 94 88 Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California TP-1 @ 3' (Slope) 2 9 101.8 123.5 TP-2 @3' (Slope) 1 17 104.8 129 TP-2 @ 7' (Slope) l 18 102.6 129 TP-2 @ 10' (Slope) 2 20 105 123.5 TP-3 @ 6' (Parking Pad) 2 5 116 123.5 TP-4 @ 4' (Parking Pad) 2 9 106.6 123.5 TP-5 @ 6' (Parking Pad) 2 10 111.2 123.5 TP-6 @ 6'(Parking Pad) 1 8 112.2 129 TP-6 @ 12'(Parking Pad) I 10 110.6 129 Assumptions and Relationships: In-place Relative Compaction = (Kd ) Km) XI 00 Gs= 2.65 e = (Gs KT) Kd) - 1 S = (T Gs)) e 82 81 80 85 94 86 90 87 86 February 10, 2015 Page 11 38 78 78 93 32 43 55 45 54 5. Expansion Index Test: Two expansion index (EI) test was performed on a representative sample of Soil Types 1 and 3 in accordance with the ASTM D-4829. The results are presented in Table 6. TABLE6 Sample Soil Molded Degree of Final Initial Dry Measured EI Location Type T Saturation T Density EI 50% (%) (%) (%) (PCF) Saturation B-3 @ 2½' 1 9 51 18 112 .9 50 50 T-1 @ 3' 2 8 41 20 109.2 35 30 Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 12 (T) = moisture content in percent. El50 = ELneas -(50 -Smeas) ((65 + ELneas) ) (220 -Smeas)) Exl)ansion Index (El) Exl)ansion Potential 0 -20 Very Low 21 -50 Low 51 -90 Medium 91 -130 High , 130 Very High 6. Direct Shear Test: One direct shear test was performed on a representative sample of Soil Type 1. The prepared specimen was 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 result is presented in Table 7. TABLE 7 Sample Soil Sample Unit Angle of Apparent Location Type Condition Weight Int. Frie. Cohesion (Kw-pd) (M-De2-) (c-pst) R-1 (ii) ?1/4' 1 Remolded to 90% ofYm @ % Topt 127.3 29 2• - 7. pH and Resistivity Test: pH and resistivity of a representative sample of Soil Type 1 was determined using "Method for Estimating the Service Life of Steel Culverts," in accordance with the California Test Method (CTM) 643 . The result is tabulated in Table 8. TABLES Sample Location Soil Type Minimum Resisthity (OHM-CM) pH B-1 @ 5' 1 270 8.4 8. Sulfate Test: A sulfate test was performed on a representative sample of Soil Type 1 in accordance with the California Test Method (CTM) 417. The result is presented in Table 9. TABLE9 Sample Location Soil Type A.mount of Water Soluble Sulfate In Soil (% by Weight) B-1 @5' 1 0.016 Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 13 9. Chloride Test: A chloride test was performed on a representative sample of Soil Type 1 in accordance with the California Test Method (CTM) 422. The result is presented in Table 10. TABLE 10 Sample Location Soil Type Amount of Water Soluble Chloride In Soil (% by Weight) B-1 @5' I 0.072 VI. SITE CORROSION ASSESSMENT A site is considered to be corrosive to foundation elements, walls and drainage structures if one or more of the following conditions exist : * Sulfate concentration is greater than or equal to 2000 ppm (0 .2% by weight). * Chloride concentration is greater than or equal to 500 ppm (0 .05 % by weight). * pH is less than 5.5 . For structural elements, the minimum resistivity of soil ( or water) indicates the relative quantity of soluble salts present in the soil ( or water). In general, a minimum resistivity value for soil ( or water) less than 1000 ohm-cm indicates the presence of high quantities of soluble salts and a higher propensity for corrosion. Appropriate corrosion mitigation measures for corrosive conditions should be selected depending on the service environment, amount of aggressive ion salts (chloride or sulfate), pH levels and the desired service life of the structure. Results oflimited laboratory tests performed on selected representative site samples indicated that the minimum resistivity is less than 1000 ohm-cm suggesting presence of high quantities of soluble salts. Test results further indicated that pH levels are greater than 5.5 and sulfate concentration is less than 2000 ppm. However, chloride concentration levels were found to be greater than 500 ppm. Based on the results of the corrosion analyses, the project site is considered corrosive and corrosion mitigation measures be incorporated into the project designs as required and determined appropriate by the design consultant. A corrosion engineer may also be consulted in this regard. Based upon the result of the tested soil sample, the amount of water soluble sulfate (SO4) was found to be 0.016 percent by weight which is considered negligible according to ACI 318, Table 4.3 .1. However, due to the site corrosion potential, Portland cement Type II and concrete with Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 14 minimum specified 28 days compressive strength (f' c) of 4,000 psi and maximum water-cement ratio of 0.50, as well as adequate reinforcement cover should be considered, as determined appropriate and confirmed by the project corrosion/structural engineer. VII. CONCLUSIONS Based upon the foregoing investigation, the planned second floor addition at the existing building and building perimeter parking improvements with new parking expansion at the southern vacant parcel is feasible from a geotechnical viewpoint. The existing building is underlain by compacted fills placed at the time of original pad construction, while dump fills and erosional mud-flow slump failure materials with large erosional cavities occur on the southern vacant parcel and adjacent slope face. Below, dense natural alluvial soils and Terrace Deposits occur. Evidence oflarge or massive existing or impending geologic instability is not indicated at the site. The following geotechnical conditions are unique to the project site and will most impact the planned second floor building addition and parking expansion improvements and the associated development costs: * Landslides, geologic hazards, gross deep seated or massive hillside instability, faults, or significant shear zones are not present at the project building addition and parking expansion sites. The project property is not located within the Alquist -Priolo earthquake fault zone established by the State of California. Liquefaction, seismically induced settlements and soil collapse, will not be a factor in the redevelopment of the project property provided our remedial grading, parking expansion pad development, ground stabilization and foundation recommendations are followed. * The project northern building pad consists of a graded lot currently supporting an existing tilt-up industrial/commercial type building. Compacted fills (map symbol Cat) on the order of 5 to 6 feet thick occur under the existing building. Records of engineering observations and compaction testing during the original pad grading and fill placement are not available for review. * Compacted fills (map symbol Cat) underlying the existing typically consist of clayey to silty sand deposits in a generally dense and compact conditions with in-place density tests indicating relative compaction levels typically ranging over 90 percent (see Boring Logs, Plates 3, 4, and 5). Minimum 90 percent compaction levels are required for well- compacted fills. Based on the results of our field and laboratory testing, underlying compacted fills are in compact conditions overall and may be considered acceptable for new foundation support. However, preparation and compaction of bottom of foundation trenches to the specified depths, and utilizing interconnected spread pad and graded beam Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 15 type foundation will be necessary for the building second floor additions, as specified below. * Dense natural alluvial soils and Terrace Deposits occur below the site fills which can suitably support the upper existing and new fills, proposed structures, improvements and graded embankments. * Building tilt-up panels separation and apparent widening near the top at the southeast corner may be the result local settlement of the underlying near surface fills in that corner, perhaps as a result of previous poor to marginal drainage allowing roof and perimeter run off waters to discharge and penetrate into the foundation soils. Above ground tight pipes are now present for proper capturing and discharging water away from the building foundations. In our opinion, drainage improvements and disallowing roof and surface water infiltrations into the foundation soils will reduce potential for future additional settlements and subsequent impacts on the tilt-up walls. Consideration should be given to locally expose the foundations at the impacted wall panel joints at the time of construction for inspections. Evidence of possible foundation cracking and distress may warrant local underpinning at the crack location. * Dump fills consist of very loose to loose, poorly-graded sandy stockpile fills (map symbol Uat) and cover the entire surfaces of the southern vacant parcel and adjacent slope face. Dump fill stockpiles have created disturbed and irregular surfaces impacted by severe erosion and erosional washout cavities. All dump fills should be removed to the underly~ng competent natural Terrace Deposits and re-graded as a part of the planned new parking expansion pad development. Deep erosional washout cavities should also be excavated exposing competent natural Terrace Deposits and backfilled with well- compacted fills property benched and keyed into the approved backcut exposures. Estimated stripping/removals and over-excavation depths are provided un the following sections. * Southern margin graded slope has experienced shallow surficial erosional and mud-flow type failures consisting of slump sliding of slope face dump fill materials within the outer few feet that had been subjected to concentrated flow and out-of-slope seepage conditions. Out-of-slope seepage has also caused washouts and local cavities within the slope. The southern margin slope should also be removed and reconstructed to existing heights at 2: 1 gradients maximum as a stabilization fill slope as a part of upper parking extension pad development, as recommended below. Slope reconstruction should excavate and remove all erosional washout cavities exposing competent natural Terrace Deposits and reconstructed with well-compacted fills property benched and keyed into . the approved backcut exposures. Backcut excavation for the slope reconstruction should be developed at 1 : 1 or flatter gradients and stabilization fill slope provided with a back Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California drainage system as specified in the following sections. February 10, 2015 Page 16 * The overall stability of graded parking expansion pad and planned improvement surfaces developed over hillside terrain is most dependent upon adequate keying and benching of new fills into the undisturbed Terrace Deposits during the adjacent slope regrading and reconstruction operations. At the project site, added care should be given to the proper construction of the toe keyway and benching excavations. * Based on our field explorations and laboratory testing, fill materials underlying the existing building chiefly consist of silty to clayey sand (SM/SC) deposits with low expansion potential ( expansion index of 50 or less) based on ASTM D-4829 classification. Expansion properties of the underlying fill soils should be considered in the new foundations and slab designs as presented below. Existing dump fills and adjacent slope face materials primarily consist of silty and locally clayey sand to sandy cohesionless to materials (SM-SC/SP). These deposits are typically highly susceptible to erosion and should be thoroughly mixed and manufactured into a uniform fill as part of the new parking expansion pad development and slope reconstruction. * New fills should be processed, moisture conditioned placed in thin horizontal lifts and compacted to at least 90% of the corresponding maximum dry densities, unless otherwise specified. The upper 12 inches of subgrade soils under the asphalt paving surfaces and upper 3 feet of utility trench backfills in the public right-of-ways should be compacted to a minimum of95% compaction levels. * Existing building floor slabs appear inadequately reinforced, lack a moisture barrier within the slab sand underlayment and have experienced numerous continuous cracks with locally apparent vertical off sets. The cracked floor slabs may be considered for total removal and replacement. Alternatively interior slabs may be locally saw cut at the cracked locations and reconstructed, as presented in the following sections. Limited slab subgrade soil preparation and compaction will be required for either alternative. * Allowable foundation bearing capacity provided in the following sections is based on the properties of onsite soils. Higher allowable foundation bearing capacity may also be established by over-excavation the foundation trenches as specified depths, placement of the layer of earth reinforcement geogrid at the exposed bottom and backfilling the trench to the bottom of the foundation level with Caltrans Class 2 crushed aggregate base type materials, as discussed in the following sections. * Wall, foundations, structures and improvements constructed on or near the top of descending slopes should be deepened or adequately setback from the top of slope to Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 17 maintain a minimum 7 feet or a of the slope height, whichever is more, horizontal setback to slope face. * Natural groundwater is not expected to be a major factor in the planned second floor addition and parking expansion. However, grading and earthwork during the dry months of the year is recommended. The proper control of stormwater and surface drainage is a critical component to the overall building performance, stability of new graded improvement surfaces, reconstructed adjacent embankments and natural open space terrain below. Stormwater and surface drainage should not be allowed to occur in a concentrated or uncontrolled flow condition over graded and natural slope surfaces. A concrete lined drainage ditch should be considered along the top of the reconstructed stability fill slope. Ponding shall not be permitted and surface drainage should be directed away from the top of the slope and building foundations. Finish slope faces should be planted soon after completion of remedial and slope repair grading and irrigation water should not be excessive. Retaining walls should be provided with a well-performing back drainage system. * Site excavations and earthwork shall not impact the adjacent properties, natural and open space terrain, structures, improvements, and underground utilities within public right-of- ways. Adequate excavation setbacks shall be maintained and temporary construction slopes developed as specified in the following sections. Added or revised field recommendations, however, may also be necessary and should be given by the project geotechnical consultant for the protection of adjacent neighboring buildings and should be anticipated. * Post construction settlements after completion of foundation soil preparation as specified herein, is not expected to exceed approximately I-inch and should occur below the heaviest loaded footings, provided our foundation system design recommendations are followed. The magnitude of post construction differential settlement as expressed in terms of angular distortion is not anticipated to exceed ½-inch between similar adjacent structural elements. VIII. RECOMMENDATIONS Recommendations provided below are consistent with the indicated geotechnical conditions at the project site and should be reflected in the final plans and implemented during the construction phase. Added or modified recommendations may also be appropriate and should be provided in a plan review report when final second story building addition, and parking expansion grading and improvement plans are available: A. Building Improvements and Second Story Addition Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 18 We understand that the existing building is planned for modifications and conversion into a medical office facility that includes a new second floor addition with the associated tenant and underground improvements. Detail architectural floor and structural foundation plans are not yet finalized and were not available at the time of preparation of this report. Based on our understanding of the project, new independent foundations are planned for the support of second floor addition. The proposed second floor addition may be supported on interconnected spread pad and grade beam type foundations constructed upon prepared foundation bearing soils as specified herein. The following recommendations are consistent with the onsite underlying silty to clayey sand (SM/SC) compacted fill deposits with low expansion potential (Expansion Index of 50 based on ASTM D-4829 classification). Other foundation support type systems and construction methods, such as pile and grade beam foundations are also available and can be provided upon request. The choice of appropriate option will depend on acceptable levels of future building and improvement performance, economic feasibility and ease of construction. Foundation recommendations provided herein should be further confirmed and/or revised as necessary at the final plan review phase. 1. New foundations should be neatly saw cut into the existing slabs, where they occur (removal and replacement of entire existing cracked interior slabs should be considered as discussed below) and foundation trenches excavated to the minimum specified depths and widths. All existing underground utilities, pipes and service lines should be pot-holed, identified and marked prior to the actual remedial grading works. 2. Spread pad footings should be at least 36 inches square and 24 inches deep and structurally interconnected with grade beams. Interconnecting grade beams and continuous strip foundations should be a minimum of 18 inches wide by 24 inches deep. Footing depths are measured from the finish subgrade levels, not including the sand/gravel layer beneath floor slabs. Actual foundation designs, reinforcements and construction details should be provided by the project structural engineer. As a minimum and from a geotechnical view point, interconnecting grade beams and continuous strip foundations should be reinforced with a minimum of 4-#5 reinforcing bars, 2-#5 bars placed 3 inches above the bottom and 2-#5 bars placed 3 inches below the top. Spread pad footings reinforcement per structural details. 3. Exposed bottom of foundation trenches should be inspected and tested for adequate ( minimum 90%) in-situ compaction levels. Below 90% compaction levels within the bearing soils will signify the need for trench over-excavations to at least 12 inches Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 19 and reconstruction to bottom of foundation level with well-compacted fills, as directed in the field. Compaction in the foundation trenches should be achieved by mechanical means using hand-held and limited access compaction equipment. 4. Based on our laboratory tests and analysis, an allowable foundation bearing capacity of2250 psf may be considered for 12 inches wide by 12 inches deep foundation supported on the existing onsite compacted soils. The indicated value may be increased by 20% for each additional foot of depth and 15% for each additional foot of width a maximum of 4500 psf, if needed. Alternatively higher allowable foundation bearing capacity can be achieved, if needed, by over-excavating bottom of foundation trench at least 18 inches, neatly placing a layer ofTerraGrid RX-1200 (or approved equal) at the over-excavated bottom and reconstruction to bottom of foundation level with minimum 95% Caltrans Class 2 crushed aggregate base type materials. In this case, an allowable foundation bearing capacity of 3000 psf may be considered for 12 inches wide by 12 inches deep foundation and increased by 20% for each additional foot of depth and 20% for each additional foot of width a maximum of 5500 psf, if needed. 5. Existing foundations should be locally exposed at the impacted wall panel joints for inspections. Local underpinning of the existing building foundations with a new grade beam should be considered in the event of possible foundation cracking. Underpinning grade beam, if required, should be a minimum of 6 feet long, matching at least the width, and extending a minimum of 12 inches below the bottom of existing foundation ( minimum 18 inches wide by 24 inches deep) and reinforced with minimum of 2-#5 bards top and bottom and #3 ties at 12 inches on centers, extending at least 3 feet on either side of the crack. The underpinning grade beam should also be tied to the existing adjacent foundations near the top and bottom with a minimum 24 inches long #5 dowels with 6 inches deep drill and epoxy grout to existing footings and 18 inches into the underpinning grade beam. Bottom of underpinning grade beam trench and bearing soil preparations will remain the same as specified. 6. Inadequately reinforced cracked existing building floor slabs should be considered for total removal and replacement. Alternatively interior slabs may be locally saw cut at the cracked locations and reconstructed. In case only the cracked portions are removed, affected slabs should be neatly saw cut a minimum of 2 feet on either side of the crack removed. A void 90 degree angles. Exposed subgrade soils underneath the interior floor slabs should then be reworked to a minimum depth of 12 inches, moisture conditioned to approximately 2% above the optimum moisture contents and recompacted to at least 90% compaction levels per ASTM D-1557. Locally more extensive subgrade reparations Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 20 including deeper over-excavations and recompaction may also be necessary based on actual field exposures and should be anticipated. The new concrete slabs should be at least 5½ inches in thickness reinforced with minimum #4 bars at 16 inches on center both ways placed mid-height in the slab. New slabs should also be provided with a minimum 8 inches wide by 12 inches thick thickened edge reinforced with minimum 1-#4 top and bottom along the perimeter and tied to the adjacent existing slabs and foundations, where they occur, with minimum 18 inches long #4 dowels at 16 inches on centers maximum, placed in 6 inches deep drill holes, thoroughly cleaned and epoxy grouted. New slabs should also be underlain with 4 inches of clean sand (SE 30 or greater) which is provided with a well performing moisture barrier/vapor retardant (minimum 15-mil Stego) placed mid-height in the sand. Alternatively, a 4-inch thick base of compacted ½- inch clean aggregate provided with the vapor barrier (minimum 15-mil Stego) in direct contact with (beneath) the concrete may also be considered provided a concrete mix which can address bleeding, shrinkage and curling is used. Provide "softcut" contraction/control joints consisting of sawcuts spaced 10 feet on centers 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 minimum I-inch in depth but should not exceed I ¼-inches deep 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. Also, provide re-entrant corner reinforcement for all interior slabs. Re-entrant corners will depend on slab geometry and/or interior column locations. The enclosed Plate 15 may be used as a general guideline. B. Parking Expansion Pad Development The southern vacant parcel is planned for a new parking expansion, and existing perimeter parking areas around building will be regraded and reconstructed to new designs as part of the site redevelopment project. Major ground modifications or the creation of new large graded slopes are not anticipated with finish design grades anticipated very near the existing elevations. Remedial grading works of the existing pad surfaces will be required in order to achieve final design grades and construct safe and stable level surfaces for the support of the planned new parking improvements. Recommended remedial grading procedures for the southern vacant parcel and adjacent eroded slope are graphically shown on the enclosed Geotechnical Remedial Grading and Slope Reconstruction Concept, Plate 16. Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 21 All excavations, grading, earthwork, construction and bearing subgrade soil preparation should be completed in accordance with Chapter 18 (Soils and Foundations) and Appendix "f' (Grading) of the 2013 California Building Code (CBC), the Standard Specifications for Public Works Construction, City of Carlsbad Grading Ordinances, the requirements of the governing agencies and following sections, wherever appropriate and as applicable: 1. Existing Underground Utilities and Buried Structures: All existing underground waterlines, sewer lines, pipes, storm drains, utilities, tanks, structures and improvements at or nearby the project remedial grading areas should be thoroughly potholed, identified and marked prior to the initiation of the actual works. Specific geotechnical engineering recommendations may be required based on the actual field locations and invert elevations, backfill conditions and proposed grades in the event of a grading conflict. Utility lines may need to be temporarily redirected, if necessary, prior to earthwork operations and reinstalled upon completion of earthwork operations. Alternatively, permanent relocations may be appropriate as shown on the approved plans. Abandoned irrigation lines, pipes, and conduits should be properly removed, capped or sealed off to prevent any potential for future water infiltrations into the foundation bearing and subgrade soils. Voids created by the removals of the abandoned underground pipes, tanks and structures should be properly backfilled with compacted fills in accordance with the requirements of this report. 2. Clearing and Grubbing: Remove all existing surface and subsurface structures, tanks, vaults, pipes, improvements, vegetation, roots, stumps, large boulders, and all other unsuitable materials and deleterious matter from all areas proposed for new fills, improvements, and structures plus a minimum of 5 horizontal feet outside the perimeter, where possible and as approved in the field. All debris generated from the site clearing, trash, and unsuitable materials should also be properly removed and disposed of Trash, vegetation and debris should not be allowed to occur or contaminate new site fills and backfills. The prepared grounds should be inspected and approved by the project geotechnical consultant or his designated field representative prior to grading and earthworks. 3. Stripping and Removals: All existing loose and eroded dump fills (see Plate 2, map symbol Uaf) at the southern vacant lot should be stripped and removed to the underlying dense and competent Terrace Deposits or well compacted fill (map Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 22 symbol Caf) placed during original site grading and recompacted. Deep erosional washout cavities, where they occur, should also be entirely excavated out to expose competent natural Terrace Deposits as a part of stripping and removal operations (also see Geotechnical Remedial Grading And Slope Reconstruction Concept, Plate 16). Actual stripping and removal depths will vary at th~ project site and should be established in the field by the project geotechnical consultant or his designated field representative. Approximate removal depths may be anticipated to be on the order of 3 to5 feet, however, locally deeper removals over the pad surfaces and in the washout cavities should also be expected as determined and directed in the field. Stripping and remedial grading should extend a minimum of 5 horizontal feet outside the improvement envelops, where possible and as directed in the field. In the building perimeter existing parking areas, existing asphalt and PCC paving surfaces should be demolished and removed and the exposed subgrade soils stripped and over-excavated to a minimum of 12 inches, unless otherwise determined or directed in the field. Some potholing and evaluation of existing subgrade soils at the time earthwork operations may be necessary to establish actual stripping and removal depths as determined and directed in the field. There should be at least 12 inches of new 95% compacted fills under the pavement base layer. The removals and over-excavations should develop level surfaces properly benched and keyed into the underlying dense and competent Terrace Deposits. The exposed bottom of all removals, over-excavations, level benches and keys should be observed and competent bedrock exposures approved by the project geotechnical consultant or his designated field representative prior to fill or backfill placement. Exploratory test pits excavated in connection with our study at the indicated locations (see Plate 2) were backfilled with loose and uncompacted deposits. The loose/uncompacted exploratory trench backfill soils shall also be re excavated and placed back as properly compacted fills in accordance with the requirements of this report. 4. Trenching and Temporary Excavation Slopes: Top of excavations and temporary slopes shall maintain adequate set back from adjacent building foundations, existing structures, on and offsite improvements and open space easements, as approved and directed in the field. Undermining and/or damages to adjacent building and nearby structures, underground utilities and street improvements within the public right-of- way, or nearby easements shall be avoided. Face of temporary slopes should be protected from excessive runoff or rainfall and stockpiling the excavated materials near the top of construction embankments should be disallowed. Construction should also be completed in a timely manner minimizing unsupported slope conditions and prolonged exposure periods. Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 23 Temporary construction slopes associated with the project remedial grading and pad construction should be developed at I : I maximum gradients, unless otherwise approved or directed in the field (also see Plate 16). The remaining wedge of exposed laid back temporary slope should then be properly benched out and new fills/backfills tightly keyed-in as the backfilling progresses. All temporary construction slopes require geotechnical inspections during the excavation operations. More specific recommendations should be given in the field by the project geotechnical consultant based on actual field exposures. Revised temporary construction slope and trenching recommendations including flatter slope gradients, larger setbacks, completing excavations and remedial grading in limited sections and the need for temporary shoring/trench shield support may be necessary and should be anticipated. The project contractor shall also obtain appropriate permits, as needed, and conform to Cal-OSHA and local governing agencies' requirements for trenching/open excavations and safety of the workmen during construction. Appropriate permits for offsite grading or excavation encroachments into neighboring private properties, easements and/or public right-of-ways may also be necessary from respective owners and agencies and should be obtained as necessary. 5. Fill/Backfill Materials, Shrinkage and Import Soils, and Compaction: Excavation of site existing dump fills and alluvial soils will chiefly generate a silty to clayey sand soil mixture which are considered suitable for reuse as site new fill, provided new fills are prepared placed and compacted in accordance with the requirements of this report. Local trash, debris, rocks larger than 6 inches and organic matter, where encountered, should be throughly removed and separated from the mixture to the satisfaction and approval of the project geotechnical consultant. Based on our analysis, on site soils may be anticipated to shrink nearly I 0% to 20% on volume basis, when compacted as specified herein. Import soils, if it becomes necessary to complete grading and achieve final design grades, should be good quality sandy granular non-corrosive deposits (SM/SW) with very low expansion potential (100% passing I-inch sieve, more than 50% passing #4 sieve and less than 18% passing #200 sieve with expansion index less than 20). Import soils should be inspected, tested as necessary, and approved by the project geotechnical engineer prior to delivery to the site. Import soils should also meet or exceed engineering characteristic and soil design parameters as specified in the followiqg sections. Project fills and backfills shall be clean deposits free of trash, debris, organic matter and deleterious materials. Uniform bearing soil conditions should be constructed at the site by the remedial grading and earthwork operations. Site soils should be Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 24 adequately processed, thoroughly mixed, moisture conditioned to slightly (2%) above the optimum moisture levels, or as directed in the field, placed in thin (8 inches maximum) uniform horizontal lifts and mechanically compacted to a minimum of 90% of the corresponding laboratory maximum dry density per ASTM D-1557, unless otherwise specified. The upper 12 inches of subgrade soils (including trench backfills) under asphalt pavement base layers should be compacted to minimum 95% compaction levels. 6. Transition Retaining Walls, Foundation Setback and Back Drainage: Transition walls may be necessary to achieve final design grades along outside perimeter of the planned parking expansion pad over the southern graded slope. The southern slope should be first reconstructed and stabilized as a part of the project grading operations as specified in the following sections. Slope reconstruction grading procedures are graphically shown on the enclosed Geotechnical Remedial Grading and Slope Reconstruction Concept, Plate 16. Wall foundations constructed on or near the top of descending slopes shall be adequately setback or deepened to maintain a minimum of 7 feet or a of the slope height, whichever is more, horizontal distance from the bottom outside edge of the footing to daylight, unless otherwise specified or approved (also see Plate 16). The specified setback requirements will apply to all structures and site improvements. Site improvements including outside perimeter of paving surfaces placed at the top of descending slopes should be provided with a thickened edge to satisfy the specified setbacks, however, minimum 5 feet horizontal distance from the bottom outside edge of the thickened edge to daylight is considered adequate for paving improvements. A well developed back drainage system should also be constructed behind the project retaining walls. The wall back drainage system should consist of a minimum 4-inch diameter, Schedule 40 (SDR 35) perforated pipe surrounded with a minimum of 1 ½ cubic feet per foot of¾-crushed rocks (12 inches wide by 18 inches deep) installed at the depths of the wall foundation level and wrapped in filter fabric (Mirafi 140-N). If Caltrans Class 2 permeable aggregate is used in lieu of the crushed rocks, the filter fabric can be deleted. The wall back drain should be installed at suitable elevations to allow for adequate fall via a non-perforated solid pipe (Schedule 40 or SDR 35) to an approved outlet. Protect pipe outlets as appropriate. All wall back drain pipes and outlets should be shown on the project final plans. A wall back drain system schematic is depicted on the enclosed Retaining Wall Drain Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 25 Detail, Plate 17. Provide appropriate waterproofing where applicable as indicated on the project pertinent construction plans. 7. Surface Drainage and Erosion Control: A critical element to the continued stability of the graded hillside pads and improvements is an adequate surface drainage system. Surface and storm water shall not be allowed to impact the developed construction and improvement sites. This can most effectively be achieved by appropriate vegetation cover and the installation of the following systems: • Uncontrolled surface run-off or flow of water over the top of adjacent slope shall be prevented. Drainage swales should be constructed at the top of slope and behind all retaining walls. • Perimeter building and parking surfaces run-off, as well as roof drainage should be properly collected and directed away from the buildings and site improvements via proper drainage control facilities and structures. Area drains should be installed. • Storm and surface run off water should not be allowed to impact or saturate graded surfaces, natural slopes and graded embankment faces, wall backfills, and bearing and subgrade soils. Concentrated run off, which could cause erosion or scouring, should be disallowed. Over watering of site vegetation should also not be allowed. Only the amount of water to sustain vegetation should be provided. • 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/erosion plans. C. Slope Reconstruction and Stabilization Southern margin graded slope has experienced shallow surficial erosional and mud- flow slump sliding of slope face dump fill materials due to concentrated flow and out-of- slope seepage conditions. The southern margin slope should also be removed and reconstructed at 2: 1 maximum gradients as a stabilization fill slope, as a part of upper parking extension pad development. Slope reconstruction should excavate and remove all erosional washout cavities exposing competent natural Terrace Deposits or dense native ground, as approved in the field, and reconstructed with well-compacted fills property benched and keyed into the approved backcut exposures. Slope reconstruction grading procedures are graphically shown on the enclosed Geotechnical Remedial Grading and Slope Reconstruction Concept, Plate 16. The following are appropriate: Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 26 1. Underground Utilities, Clearing and Grubbing: Locating and marking all underground utility prior to any excavations and grading operations, as well as clearing and grabbing of surface vegetation, plants, trees, deleterious materials and debris remain the same as previously specified. 2. Limits of Grading and Slope Reconstruction: Existing slope is not well defined and embankment toe currently blended into the surrounding areas due to severe erosion. Limits of the southern graded slope should be established on the project plans and boundaries with the adjacent open easement well established, if applicable. The enclosed Geotechnical Remedial Grading and Slope Reconstruction Concept (Plate 16) assumes an arbitrary toe for the new embankment and achieving 2: 1 maximum gradients. Actual slope top and toe locations and design configurations per the project grading designs and approved plans. 3. Removals of Eroded and Unstable Outer Slope Face Soils: Remove existing very loose soil and erosional failure slumps from within the outer slope face. Removals should extend into dense alluvial soils or competent Terrace Deposits along the toe of the slope where a new keyway should be established. Grading operations should effectively remove all existing loose dump fills and slope face failure soils and expose level benches on the temporary backcut side throughout as shown on Plate 15. The level benches should be constructed in a manner that there is a minimum of 10 feet (horizontally) of new compacted fill from the outside edge (front) of the bench to the finish slope face, and keyed a minimum of 2 feet into the temporary back side unless otherwise directed or approved in the field. 4. Establish A Toe Keyway: Establish a lower toe keyway at the base of slope. The toe keyway should be at least 15 feet wide and maintain a minimum depth of 3 feet below the lower toe levels developed into the underlying dense native ground or Terrace Deposits. The keyway should expose dense native ground (in-place densities of90% or greater) or competent Terrace Deposits throughout with the bottom heeled back a minimum of 5% into the natural hillside and inspected and approved by the project geotechnical engineer. Fills can only be placed on stable and competent bottom of keyway excavations. In the event suitably competent bottom of keyways receiving fills is not encountered at the specified depths (less than minimum 90% in-place compaction levels) as determined by the project geotechnical engineer, deeper keyway excavation will be required as established in the field. Alternatively, a layer ofTerraGrid RX-1200 may be provided at the approved bottom of the keyway as directed by the project geotechnical consultant. Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 27 5. Staging and Stockpiling: Slope stabilization and reconstruction work should be completed with no impact on the adjacent open space areas. Appropriate temporary devices should be installed and proper measures taken during earthwork to protect nearby areas and grading contained within the designated areas as delineated on the approved plans. Onsite staging and stockpiling areas should be determined and approved prior to actual work. 6. Temporary Backcut Slope: Excavations and development of temporary backcut for the recommended slope reconstruction remains the same as specified. Temporary backcut required to complete slope reconstructions should be developed at 1: 1 or flatter gradients unless otherwise specifically approved or directed in the field. Temporary backcut slope should be developed into unaffected hillside exposing dense native ground or competent Terrace Deposits effectively removing all existing dump fill, erosional slump failures, and washout cavities. See Plate 2 for approximate limits of dump fill soils (map symbol, Uat). The remaining wedge of soil should then be benched out and new fill tightly keyed-in as the backfill placement progresses. 7. Subdrain: A critical element to the continued stability of the reconstructed slope is an adequate subdrainage system. This can most effectively be achieved by the installation of a back drain in a bench above the keyway at a suitable elevation to ensure positive gravity flow as shown on Plate 15. Actual locations should be determined by the project geotechnical engineer in the field. The subsurface back drains should consist of a 4-inch perforated Schedule 40 (SDR 35) pipe surrounded with ¾-crushed rock and wrapped in Mirafi 140N filter fabric material as depicted on the attached Plate 15. Filter fabric can be eliminated if Caltrans Class 2 permeable aggregates are used. Solid outlet tight line pipes should also be Schedule 40 (SDR 35) as shown. Water collected in the recommended back drains should be directed via the solid outlet pipe at every 100 feet maximum to suitable locations and/or drainage facilities. Cap ends of perforated back drain pies and protect all solid pipe outlets. Riser-cleanouts should also be placed at the perforated-solid pipe connection points as necessary. 8. Groundwater and Earth Materials: Groundwater was not encountered in our exploratory excavations to the depths explored at the time of our field work and is not expected to be major geotechnical concern during slope reconstruction work. Minor water seeps, however may develop during the site excavations requiring local dewatering and mitigation. Any effective method which can remove the intruding water and create safe site conditions that allow for fill placement and slope reconstruction is acceptable. Additional specific recommendations, including the need for a rock stabilization mat and higher compaction levels for fills subject to Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 28 potential saturations should be given by the project geotechnical consultant based on actual field conditions at that time. Grading and earthworks during the dry months of the year are recommended. Removed soils are also considered suitable for reuse in slope reconstruction, provided they are properly cleaned with all trash debris, if any, vegetation, roots, and organic matter throughly separated and removed as specified. New fills shall be approved by the project geotechnical consultant prior to their reuse. Estimated shrinkage of onsite soils and import soils requirements will also remain the same as specified. 9. Slope Reconstruction: Reconstruct the slope by placing fills in thin, horizontal lifts upon approved keyway excavations and the level benches to achieve original (2: 1 maximum) slope gradients. The reconstructed slope should be neatly rounded and blended into the surrounding terrain. Fill soils should be adequately processed, properly mixed, moisture conditioned to approximately 2% above optimum levels as directed in the field, manufactured into a uniform mixture, placed in thin (8 inches maximum) lifts and mechanically compacted to a minimum of90% of the laboratory maximum dry density value in accordance with ASTM D-1557, unless otherwise specified. The reconstructed fill slope should be compacted to a minimum of 90% out to the slope face. Back rolling at a minimum of 4-foot vertical increments and trackwalking the completed slope, or over-building the slope and cutting back to design configurations, is recommended. Field density tests should be performed to confirm adequate compaction levels within the slope face. 10. Surface Drainage: Controlling slope face surface runoff is an important factor in the overall stability of the project regraded embankment. Site drainage over the finish slope face should not be allowed to occur in a concentrated flow condition. Overflow of the upper parking surface water from the top of the slope should be collected in or pavement edge curb and gutters or captured by installing concrete lined drainage ditches at the top of the slope. Erosion and drainage control structures and facilities should be installed per approved plans. Appropriate drainage improvements specific to the site conditions should be design by the project consultant and shown on the final plans. 11. Planting: The finish slope should be planted soon after completion of grading per the project approved landscape plan. Natural brush is best but difficult to quickly establish. Initially, only broad-leafed, deep-rooted vegetation which requires a minimum of irrigation should be used. Slope face planting should be well managed Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 29 and maintained. Only the minimum amount of water to sustain vegetation life should be provided. A qualified landscape architect may be consulted in this regard. D. Soil Design Parameters The following soil design parameters are based upon tested representative samples of on- site earth deposits and our experience with similar earth deposits in the vicinity of the project site. All parameters should be re-evaluated when the characteristics of the final as-graded soils have been specifically determined: • Design unit weight= 127 pcf. • Design angle of internal friction = 29 degrees. • Design active pressure for retaining structures = 45 pcf (EFP), level backfill, cantilever, unrestrained walls. • Design active pressure for retaining structures = 72 pcf (EFP), 2: 1 sloping backfill, cantilever, unrestrained walls. • Design at-rest pressure for retaining structures= 61 pcf (EFP), non-yielding, restrained walls. • Design passive resistance for retaining structures = 366 pcf (EFP), level surface on the toe side, soil mass extends a minimum of 10 feet or 3 times the height of the surface generating passive resistance, whichever is more. • Design passive resistance for retaining structures = 140 pcf (EFP), 2: 1 sloping down surface on the toe side. • Design coefficient of friction for concrete on compacted fills= 0.35. • Design net allowable foundation pressure for compacted fills (minimum 12 inches wide by 12 inches deep footings)= 2250 psf. • Allowable lateral bearing pressure for compacted fills ( all structures except retaining walls) = 150 psf/ft. Notes: -Added lateral pressures caused by nearby foundations, improvements, and vehicular surcharge loading should be considered by the project structural engineer as appropriate. For this purpose, adding 2 feet to the overall wall heights considered in the designs, or other appropriate design modeling methods corresponding to the surcharge loading condition may be used. -Use a minimum safety factor of 1.5 for wall overturning 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. Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 30 -When combining passive pressure and frictional resistance, the passive component should be reduced by one-third. -The net allowable foundation pressures provided herein were determined based on the specified foundation bearing strata, and foundation depths and widths. The indicated value may be increased by 20% for each additional foot of depth and 15 for each additional foot of width to a maximum of 4500 psf, if needed. Higher allowable foundation bearing capacity can also be achieved, if needed, by placing a layer ofTerraGrid RX-1200 (or approved equal) a minimum of 18 inches below the bottom of the foundations and achieving bottom of foundation level with minimum 95% Caltrans Class 2 crushed aggregate base type materials, as specified in the preceding sections. In his case, an allowable foundation bearing capacity of 3000 psf may be considered for 12 inches wide by 12 inches deep foundation and increased by 20% for each additional foot of depth and 20% for each additional foot of width a maximum of 5500 psf, if needed. The allowable foundation pressures 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 of the designated value for each additional foot of depth to a maximum of 1500 pounds per square foot. E. Exterior Concrete Slabs / Flatworks 1. All exterior slabs (walkways, patios) supported on low expansive subgrade soils should be a minimum of 4 inches in thickness, reinforced with #3 bars at 18 inches on centers in both directions placed mid-height in the slab. The subgrade soils should be compacted to minimum 90% compaction levels at the time of fine grading and before placing the slab reinforcement. 2. Reinforcements lying on subgrade will be ineffective and shortly corrode due to lack of adequate concrete cover. Reinforcing bars should be correctly placed extending through the construction joints tying the slab panels. In construction practices where the reinforcements are discontinued or cut at the construction joints, slab panels should be tied together with minimum 18 inches long #3 dowels ( dowel baskets) at 18 inches on centers placed mid-height in the slab (9 inches on either side of the joint). 3. Provide "tool joint" or "softcut" contraction/control joints spaced 10 feet on center (not to exceed 12 feet maximum) each way. The larger dimension of any panel shall not exceed 125% of the smaller dimension. Tool or cut as soon as slab will Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 31 support weight, and can be operated without disturbing the final finish which is normally within 2 hours after final finish at each control joint location or 150 psi to 800 psi. Tool or softcuts should be a minimum of ¾-inch but should not exceed I- inch deep maximum. In case of softcut joints, anti-ravel skid plates should be used and replaced with each blade to avoid spalling and raveling. A void wheeled equipments across cuts for at least 24 hours. Joints shall intersect free-edges at a 90° angle and shall extend straight for a minimum of 1 ½ feet from the edge. The minimum angle between any two intersecting joints shall be 80°. Align joints of adjacent panels. Also, align joints in attached curbs with joints in slab panels. Provide adequate curing using approved methods (curing compound maximum coverage rate= 200 sq. ft./gal.). 4. All exterior slab designs should be confirmed in the final as-graded compaction report. 5. Subgrade soils should be tested for proper moisture and specified compaction levels and approved by the project geotechnical consultant prior to the placement of concrete. F. Preliminary Pavement Design Specific pavement designs can best be provided at the completion of rough grading based on testing (R-value tests) of the actual finish subgrade soil mixture; however, the following structural sections may be considered for initial planning phase and cost estimating purposes only (not for construction): 1. Asphalt Paving: A minimum section of 4 inches asphalt on 6 inches Caltrans Class 2 aggregate base or the minimum structural section required by City of Carlsbad, whichever is more, may be considered for the on-site asphalt paving surfaces outside the private and public right-of-way. Actual designs will depend on final subgrade R- .value and design TI, and the approval of the City of Carlsbad. The Class 2 aggregate base shall meet or exceed the requirements set forth in the current California Standard Specification (Caltrans Section 26-1.02). Base materials should be compacted to a minimum 95% of the corresponding maximum dry density (ASTM D-1557). Subgrade soils beneath the asphalt paving surfaces . should also be compacted to a minimum 95% of the corresponding maximum dry density within the upper 12 inches. 2. PCC Pavings: Commercial/industrial PCC driveways and parking supported on low Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 32 expansive subgrade soils should be a minimum 5½ inches in thickness, reinforced with #4 reinforcing bars at 18 inches on centers each way placed at mid-height in the slab. Subgrade soils beneath the PCC driveways and parking should be compacted to a minimum 90% of the corresponding maximum dry density. Reinforcing bars should be correctly placed extending through the construction ( cold) joints tying the slab panels. In construction practices where the reinforcements are discontinued or cut at the construction joints, slab panels should be tied together with minimum 18-inch long (9 inches on either side of the joint) #4 dowels ( dowel baskets) placed at the same spacing as the slab reinforcement. Provide "tool joint" or "softcut" contraction/control joints spaced IO feet on center (not to exceed 15 feet maximum) each way. The larger dimension of any panel shall not exceed 125% of the smaller dimension. Tool or cut as soon as the slab will support the weight and can be operated without disturbing the final finish which is normally within 2 hours after final finish at each control joint location or 150 psi to 800 psi. Tool or softcuts should be a minimum of I-inch in depth but should not exceed I ¼-inches deep maximum. In case of softcut joints, anti-ravel skid plates should be used and replaced with each blade to avoid spalling and ravelings. A void wheeled equipments across cuts for at least 24 hours. Joints shall intersect free edges at a 90E angle and shall extend straight for a minimum of I½ feet from the edge. The minimum angle between any two intersecting joints shall be 80E. Align joints of adjacent panels. Also, align joints in attached curbs with joints in slab panels. Provide adequate curing using approved method (curing compound maximum coverage rate= 200 sq. ft./gal.). 3. General Paving: Base section and subgrade preparation per structural section design, will be required for all surfaces subject to traffic including roadways, travelways, drive lanes, driveway approaches and ribbon (cross) gutters. Driveway approaches within the public right-of-way should have 12 inches subgrade compacted to a. minimum of 95% compaction levels and provided with a 95% compacted Class 2 base section per structural section design. Base layer under curb and gutters should be compacted to a minimum 95%, while subgrade soils under curb and gutters, and base and subgrade under sidewalks should be compacted to a minimum 90% compaction levels. Appropriate recommendations should be given in the final as-graded compaction report. Base and subgrade soils should be tested for proper moisture and specified compaction levels, and approved by the project geotechnical consultant prior to the Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California placement of the base or asphalt/PCC finish surface. IX. ENGINEERING OBSERVATIONS AND TESTING -February 10, 2015 Page 33 All grading and earthwork operations including excavations, stripping and removals, suitability of earth deposits used as compacted fills and backfills, import soils, and compaction procedures should be continuously observed and tested by the project geotechnical consultant and presented in the final as-graded compaction report. The nature of finished bearing and subgrade soils should be confirmed in the final compaction report at the completion of grading. Geotechnical engineering observations should include but are not limited to the following: 1. Initial observation: After grading and clearing limits have been staked but before grading operations starts. 2. Stripping, bottom of keyway/excavation observation: After dense native ground or competent Terrace Deposits are exposed and prepared to receive fill or backfill but before fill or backfill is placed. 3. Cut/excavation observation: 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. 4. Fill/backfill observation: After the fill/backfill placement is started but before the vertical height of fill/backfill exceeds 2 feet. A minimum of one test shall be required for each 100 lineal feet maximum in every 2 feet vertical gain, with the exception of wall backfills where a minimum of one test shall be required for each 30 lineal feet maximum. Wall backfills should also be mechanically compacted to a minimum of90% compaction levels unless otherwise specified or directed in the field. Finish rough and final pad grade tests shall be required regardless of fill thickness. 5. Foundation trench and subgrade soil observation: After the foundation trench excavations and prior to the placement of steel reinforcing for proper moisture and specified compaction levels. 6. Geotechnical foundation/slab steel observation: After the steel placement is completed but before the scheduled concrete pour. 7. Underground utility, plumbing and storm drain trench observation: After the trench excavations but before placement of pipe bedding or installation of the underground facilities. Local and Cal-OSHA safety requirements for open excavations apply. Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 34 Observations and testing of pipe bedding may also be required by the project geotechnical engineer. 8. Underground utility, plumbing and storm drain trench backfill observation: 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. Onsite trench backfills should be mechanically compacted to a minimum of 90% compaction levels unless otherwise specified. Trench backfills within the city and public right-of-ways should be compacted to minimum 95% within the upper 3 feet. Plumbing trenches more than 12 inches deep maximum under the 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 should not be allowed. 9. Pavement/improvements base and subgrade observation: Prior to the placement of concrete or asphalt for proper moisture and specified compaction levels. X. GENERAL RECOMMENDATIONS 1. 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. 2. Adequate staking and grading control is a critical factor in properly completing the recommended slope reconstruction, remedial and site grading operations. Grading control and staking should be provided by the project grading contractor or surveyor/civil engineer, and is beyond the geotechnical engineering services. Staking should apply the required setbacks shown on the approved plans and conform to setback requirements established by the governing agencies and applicable codes for off-site private and public properties and property lines, utility and open space easements, right-of-ways, nearby structures and improvements, leach fields and septic systems, and graded embankments. Inadequate staking and/or lack of grading control may result in illegal encroachments or unnecessary additional grading which will increase construction costs. 3. Footings located on or adjacent to the top of descending slopes should be adequately setback or extended to a sufficient depth to provide a minimum horizontal distance to the slope face, as specified in this report (minimum 7 feet or a of the slope height, whichever is more). Site concrete flat woks and paving improvements near the top of descending slopes should also be provided with a thickened edge to satisfy the specified (minimum of 5 feet) horizontal distances or set back to daylight, unless otherwise noted or required. Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 35 4. Open or backfilled trenches parallel with a footing shall not be below a projected plane having a downward slope of I-unit vertical to 2 units horizontal ( 50%) from a line 9 inches above the bottom edge of the footing, and not closer than 18 inches from the face of such footing. 5. Where pipes cross under-footings, the footings shall be specially designed. Pipe sleeves shall be provided where pipes cross through footings or footing walls, and sleeve clearances shall provide for possible footing settlement, but not less than I-inch all around the pipe. 6. Foundations where the surface of the ground slopes more than 1 unit vertical in 10 units horizontal ( I 0% slope) shall be level or shall be stepped so that both top and bottom of such foundations are level. Individual steps in continuous footings shall not exceed 18 inches in height and the slope of a series of such steps shall not exceed 1 unit vertical to 2 units horizontal ( 50%) unless otherwise specified. The steps shall be detailed on the structural drawings. The local effects due to the discontinuity of the steps shall also be considered in the design of foundations as appropriate and applicable. 7. Expansive, clay rich soils should not be used for backfilling of any retaining structure. All retaining walls should be provided with a 1: 1 wedge of good quality sandy granular, compacted backfill soils measured from the base of the wall footing to the finished surface and a well-constructed back drain system as shown on the enclosed Plate 17. Planting large trees behind site retaining walls should be avoided. 8. All underground utility and plumbing trenches should be mechanically compacted to a minimum of 90% of the maximum dry density of the soil unless otherwise required or specified. Trench backfills within the city and public right-of-ways shall conform to the requirements of governing agencies and compacted to minimum 95% within the upper 3 feet. Care should be taken not to crush the utilities or pipes during the compaction of the soil. Very low expansive, sandy granular backfill soils should be used. 9. Excessive irrigation resulting in wet soil conditions should be avoided. Surface water should not be allowed to occur in a concentrated flow condition or infiltrate into the wall backfills, underlying bearing and subgrade soils. 10. Site drainage over the finished pad surfaces should flow away from structures, improvements and top of embankments 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. Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 36 11. All foundation trenches should be inspected to ensure adequate footing embedment into approved bearing strata and confirm competent bearing soils. Foundation and slab reinforcements should also be inspected and approved by the project geotechnical consultant. 12. The amount of shrinkage and related cracks that occur 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 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 ct-inch maximum size aggregate usually requires about 40-lbs. more (nearly 5-gal.) water per cubic yard than concrete with I-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. 13. A preconstruction meeting between representatives of this office, the property owner or planner, city inspector as well as the grading contractor/builder is recommended in order to discuss grading and construction details associated with site development. XI. GEOTECHNICAL PLAN REVIEW Accurate grading and drainage designs should be completed by the project civil engineer based on the geotechnical factors and recommendations presented herein. The project structural designs or the second story addition should also incorporate recommendations provided in this report. Final grading, drainage and foundation plans should also be provided to the project geotechnical consultant for review. If the final plans are different from those conditions used as a basis of our study and site evaluations, additional and/or revised recommendations may be necessary and should be anticipated. Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California XII. GEOTECHNICAL ENGINEER OF RECORD (GER) February 10, 2015 Page 37 SMS Geotechnical Solutions, Inc. is the geotechnical engineer of record (GER) for providing a specific scope of work or professional service under a contractual agreement unless it is terminated or canceled by either the client or our firm. In the event a new geotechnical consultant or soils engineering firm is hired to provide added engineering services, professional consultations, engineering observations and compaction testing, SMS Geotechnical Engineering Solutions, Inc. will no longer be the geotechnical engineer of the record. Project transfer should be completed in accordance with the California Geotechnical Engineering Association (CGEA) Recommended Practice for Transfer of Jobs Between Consultants. The new geotechnical consultant or soils engineering firm should review all previous geotechnical documents, conduct an independent study, and provide appropriate confirmations, revisions or design modifications to his own satisfaction. The new geotechnical consultant or soils engineering firm should also notify in writing SMS Geotechnical Solutions, Inc. and submit proper notification to the City of Carlsbad for the assumption of responsibility in accordance with the applicable codes and standards (1997 UBC Section 3317.8). XIII. LIMITATIONS The conclusions and recommendations provided herein have been based on available data obtained from the review of pertinent reports and plans, subsurface exploratory excavations as well as our experience with the soils and formational materials located in the general area. The materials encountered on the project site and utilized in our laboratory testing are believed representative of the total area; however, earth materials may vary in characteristics between excavations. Of necessity, we must assume a certain degree of continuity between exploratory excavations and/or natural exposures. It is necessary, therefore, that all observations, conclusions, and recommendations be verified during the grading operation. In the event discrepancies are noted, we should be contacted immediately so that an inspection can be made and additional recommendations issued if required. The recommendations made in this report are applicable to the site at the time this report was prepared. It is the responsibility of the owner/developer to ensure that these recommendations are carried out in the field. It is almost impossible to predict with certainty the future performance of a property. The future behavior of the site is also dependent on numerous unpredictable variables, such as earthquakes, rainfall, and on-site drainage patterns. Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California February 10, 2015 Page 38 The firm of SMS Geotechnical Solutions, Inc., shall not be held responsible for changes to the physical condition of the property such as addition of fill soils, added cut slopes, or changing drainage patterns which occur without our inspection or control. 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 reconstruction 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. This report is issued with the understanding that the owner or his representative is responsible for ensuring that the information and recommendations are provided to the project architect/structural engineer so that they can be incorporated into the plans. Necessary steps shall be taken to ensure that the project general contractor and subcontractors carry out such recommendations during construction. The project geotechnical engineer should be provided the opportunity for a general review of the project final design plans and specifications in order to ensure that the recommendations provided in this report are properly interpreted and implemented. If the project geotechnical engineer is not provided the opportunity of making these reviews, he can assume no responsibility for misinterpretation of his recommendations. SMS Geotechnical Solutions, 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 Project No. GI-12-14-34 will help to expedite our response to your mqumes. We appreciate this opportunity to be of service to you. SMS Geotechnical Solutions, Inc. S. Mehdi S. Shariat GE #2885 Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California Steven J. Melzer CEG#2362 Distribution: Addressee (5, e-mail) Hofman Planning & Engineering; Mr. Eduardo Cadena (mail) February 10, 2015 Page 39 Geotechnical Investigation, Second Floor Addition and New Parking Improvements, 6125 Paseo Del Norte, Carlsbad, California REFERENCES February 10, 2015 Page 40 -Annual Book of ASTM Standards, Section 4 -Construction, Volume 04.08: Soil and Rock (I); D 420 - D 5876, 2012. -Annual Book of ASTM Standards, Section 4 -Construction, Volume 04.09: Soil and Rock (II); D 5876 -Latest, 2012. -Highway Design Manual, Caltrans. Fifth Edition. -Corrosion Guidelines, Caltrans, Version 1. 0, September 2003. -California Building Code (CBC), California Code of Regulations Title 24, Part 2, Volumes 1 & 2, 2013, International Code Council. -"Green Book" Standard Specifications for Public Works Construction, Public Works Standards, Inc., BNi Building News, 2006 Edition. -California Geological Survey, 2008 (Revised), Guidelines for Evaluating and Mitigating Seismic Hazards in California, Special Publication 117 A, 108p. -California Department of Conservation, Division of Mines and Geology (California Geological Sqrvey), 1986 (revised), Guidelines for Preparing Engineering Geology Reports: DMGNote44. -California Department of Conservation, Division of Mines and Geology (California Geological Survey), 1986 (revised), Guidelines to Geologic and Seismic Reports: DMG Note 42. -EQFAULT, Ver. 3.00, 1997, Deterministic Estimation of Peak Acceleration from Digitized Faults, Computer Program, T. Blake Computer Services and Software. -EQSEARCH, Ver 3.00, 1997, Estimation of Peak Acceleration from California Earthquake Catalogs, Computer Program, T. Blake Computer Services and Software. -Tan S.S. and Kennedy, M.P., 1996, Geologic Maps of the Northwestern Part of San Diego County, California, Plate(s) 1 and 2, Open File-Report 96-02, California Division of Mines and Geology, 1 :24,000. -"Proceeding of The NCEER Workshop on Evaluation of Liquefaction Resistance Soils," Edited by T. Leslie Youd and Izzat M. Idriss, Technical Report NCEER-97-0022, Dated December 31, 1997. -"Recommended Procedures for Implementation of DMG Special Publication 117 Guidelines for Analyzing and Mitigation Liquefaction in California," Southern California Earthquake Center; USC, March 1999. REFERENCES (continued) -"Soil Mechanics," Naval Facilities Engineering Command, DM 7.01. -"Foundations & Earth Structures," Naval Faci.lities Engineering Command, DM 7.02. -"Introduction to Geotechnical Engineering, Robert D. Holtz, William D. Kovacs. -"Introductory Soil Mechanics and Foundations: Geotechnical Engineering," George F. Sowers, Fourth Edition. -"Foundation Analysis and Design," Joseph E. Bowels. -Caterpillar Performance Handbook, Edition 29, 1998. -Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas, California Division of Mines and Geology, Geologic Data Map Series, No. 6. -Kennedy, M.P., 1977, Recency and Character of Faulting Along the Elsinore Fault Zone in Southern Riverside County, California, Special Report 131, California Division of Mines and Geology, Plate 1 (East/West), 12p. -Kennedy, M.P. and Peterson, G.L., 1975, Geology of the San Diego Metropolitan Area, California: California Division of Mines and Geology Bulletin 200, 56p. -Kennedy, M.P. and Tan, S.S., 1977, Geology of National City, Imperial Beach and Otay Mesa Quadrangles, Southern San Diego Metropolitan Area, California, Map Sheet 24, California Division of Mines and Geology, 1 :24,000. -Kennedy, M.P., Tan, S.S., Chapman, R.H., and Chase, G.W., 1975, Character and Recency of Faulting, San Diego Metropolitan Areas, California: Special Report 123, 33p. -"An Engineering Manual for Slope Stability Studies," J.M. Duncan, A.L. Buchignani and Marius De Wet, Virginia Polytechnic Institute and State University, March 1987. -"Procedure to Evaluate Earthquake-Induced Settlements in Dry Sandy Soils," Daniel Pradel, ASCE Journal of Geotechnical & Geoenvironmental Engineering, Volume 124, #4, 1998. -"Minimum Design Loads for Buildings and Other Structures," ASCE 7-10, American Society of Civil Engineers (ASCE). PRIMARY DI\.1SIONS GROu"P SECONDARY DMSIONS SYMBOL GR.A..VELS CLEAN GRAVELS GW Well gradtd jl2vels, pve\-51lld mixtures, little« no~, (LESSTHA."1 OP MORE TH.~'\ HALF OF 5%FJNES) Poorly if3:le<! gravels or i!'lvti-nnd mixlUl'es. lit'Je or no fines. COARSE GR..;.NED COARSS FR.A.CTTION IS GRAVELS GM SOILS Silty p.ve!s, gravel-send mi=es.. n<Jn-plastic fir.es LARGSR THAN NO. 4 WITH MORE THA.'i HALF OF SIEVE FINES GC Clayey gravels, gnvel-sand-c:ay lllixn:res, plastic Imes MATERlAL IS LARGER SANDS CLEANSA;"1DS SW Weli pded stru!s, pa;-.liy =<ls, linlo or no fit:es. THAN NO. 200 SIEVE (LESS THAN SIZE MORE TH.~"1 HALF OF 5% FINES) SP Poorly jndtd =ds, gnvelJ-j$Uds, little or no fines. COARSE FRACTT!ON IS Sk'\:-0S SM Silty sands, ~-nlr i:iilrnlrti, con-plutic firM SMALLER THA.\1 NO. 4 WITH SIEVE FINES SC Claye w,ds, sar.d-el&y rnlxtweS, plastic iines SILTS&CLAYS !\!L loo:pcic silts ar,d very :!i~ sands, roek flom, silty or clayey fl.ne sar.ds or c:a,,.,v silu "'itbslioht nwti..--'tv FINEGR.~ED CL lnorp,,k tlays o!!owto me&uzn plasticity, V,,Vtlly cb!ys, sandy c!rft, SOILS LIQUID LIMIT IS siltv c!n"S, lean cls-v-s LESS TH..;.N 50% OL Orpni, silts lild orpn!e sUtyc!ay. oftov.• plasti:ity MORE THA,~ HALF OF MH lncrpr.ie siits. micaceous or diatomaceOUS nae suid-t or rut, sci!s, MATERLUISSMAl.LER S!l. TS & CLAYS el&sue soils THAN NO. 200 SIEVE CH lncrpn.~ clays ofhisJ, plasticity, fat e!ays SIZE L!Ql:ID LIMIT IS MORE TH.A...°'i SO¾ OH Organic days of medium to h:ih plasticity, orpnie silts HIGHL YORGA.~IC SOILS PT !'e&t or otl:-er highly orpnie JOils GR-'\IN SIZES U.S. ST A.'-iDARD SERIES SJEVE CL:EAll SQAll1l.E SIEVE O?END<GS 20C 40 10 4 ¾" 3" 12" SAND GRAVEL SIL TS & CLAYS I COARSE COBBLES BOULDERS FINE MEDIUM COARSE FDiE RELATIVE DENSITY CONSISTENCY SANDS, GRAVELS&. 3LOWSIFOOT CLAYS& STRENG:H BLOWS/FOOT NON-PLASTIC SILTS PI..o.STIC SILTS VERY LOOSE 0-4 VERY SOFT 0-¾ 0-2 SOFT ¾-½ 2-4 LOOSE 4-10 FJR.'1,,,1 ½-1 4-8 MED!t.JM DENSE 10-30 STIFF I -2 g. 16 DENSE 30 • SC VERY STIFF 2-4 16-32 VERY DENSE OVER50 HARD OVER4 OVER32 ! . BLOW COCNT: 140 POt,;'N1) HA.'£1ER FALLING 30-INCHES ON A 2-INCH DL6-METER O.D. SPLIT SPOON SAMPLER (AS1M D-1586) 2. UNCONFINED COMPRESSiVE STRENGTH PER SOIL TEST POCKET PENETROMETER CL-700 T Sand Cone Test ■ Bulk Sample 8\ Standard Penetration Test (SPT)-(ASTM D-1586) With Blow Counts Per 6-Inches □ Chunk Sample Q Driven Rings ~\ California Sampler With Blow Counts Per 6-Inches 3MS fiEOTECHNICAL SO!IZ11Qfv~, 11l'1. KEY TO BORL?l{G / TEST PITS LOGS Co1ISldting Geoucludcal Engluen & Geologists UNIFIED SOIL CLASSIFICATION SYSTEM. (ASTM D-2481) c.ee..-w. ws . Date: January 16, 2015 DEPTH (ft) -0- - 2 - - 4 - SAMPLE O□ 25,30 8-1 DESCRIPTION 5½" Concrete slab. Welded wire mesh uses Symbol 1 reinforcement (may be 6x6-10x10) approximately 4" below top of slab. / Approximately 4" of clean sand beneath slab. No moisture barrier. J.----------+---- Compacted Fill (Cat): Silty to clayey fine to medium. Tan to brown SM/SC Logged by: SMS Field Moisture (%} 9 F~dDry Density (pcf) 117.5 Relallve Comp. (%) 91 Saturation 5(%) 60 II color. Moist. Tight. Well compacted. -6 -~ □ Locally grades more clay-rich. ST-1 J------+---+--t-------41 - - 8 - -10 - -12 - -14 - -16 - -18- 1, 9, 15 / (24) --------------------- 0 Alluvium (Qal}: 21,21 Ii 6, 12, 13 (25) 0 21,27 II 6, 10, 11 Silty to clayey sand. Light brown color. Local rust-colored staining. Moist. Tight. Dense. ST-1 SM/SC Medium to coarse clayey sand. Tan to brown color. Moist to very moist. Dense to very dense. (May be weathered formational rock). ST-2 SP/SC ' 14 113.2 88 81 13 112.7 91 73 -20 '""-ll--..... /?'.1.1.,11\_, End Test Boring @ 20' No Caving No Groundwater SM S Geotechnical Solutions, Inc. 1700 Aviara Parkway Carlsbad, California 92013 II SPT Sample □ Bulk Sample BORING LOG 6125 Paseo Del Norte, Carlsbad Job No. GI-12-14-34 PLATE 3 0 Driven Rings Date: January 16, 2015 Logged by: SMS B-2 Field Field Ory Relative Saturation DEPTH SAMPLE uses Mobture Otnsity Comp. S(%) (ft) DESCRIPTION SymbOI (%) (pcf) (%) - 0 -5½"-6" Concrete slab. Welded wire mesh --\ reinforcement (may be 6x6-10x10) approximately 4½" below top of slab. I - 2 - Approximately 4" of clean sand beneath slab. No moisture barrier. --0 Compacted Fill (Caf): 10 118.9 92 68 - 4 -36.55 Silty to clayey fine to medium. Tan to brown 0\ color. Moist. Very Tight. Well compacted. ' -6-Locally not well mixed. ST-1 SM/SC/ 12 114.8 93 72 --24.42 - 8 - Terrace Deposit (Qt): --Sandstone. Fine to medium grained. Locally -10-II trace clay. Light brown color. Slightly moist 7, 11, 13 to moist. Dense to very dense. ST-2 (24) SM/SC -- -12 - II --9, 10, 11 Continues dense to very dense. (21) -14 - - - 0 13 118.8 96 88 -16--25,33 - - End Test Boring @ 16' -18 - No Caving --No Groundwater -20 - SM S Geotechnical Solutions, Inc. BORING LOG 1700 Aviara Parkway 6125 Paseo Del Norte, Carlsbad Carlsbad, California 92013 Job No. GI-12-14-34 PLATE4 11 SPT Sample D Bulk Sample 0 Driven Rings Date: January 16, 2015 Logged by: SJM B-3 Field Field Ory Relative Saturation DEPTH SAMPLE uses Moisture Density Comp. S(%) (ft) DESCRIPTION Symbol (%) (pef) (%) -0-6"-7" Concrete slab. Welded wire mesh oJ reinforcement (may be 6x6-10x10) --approximately 5½" below top of slab. -2 -Approximately 4" of clean sand beneath slab. 11 117.3 91 73 No moisture barrier. I 11, 12 -- -4 - Compacted Fill (Caf}: Silty to clayey fine to medium. Dark brown to I 124\ red brown color. Moist. Compacted. SM/SC 14 116.6 94 88 -6 -Somewhat plastic. ST-1 J --Terrace Deposit {Qt}: -8 - Sandstone. Fine to medium grained. Trace --clay. Red brown color. Weathered. -10 -Massive. Moderately cemented. Medium II dense to dense. ST-2 SM/SC --4, 7,8 (15) Stiff, dark grey clay lens in sample at 1 O'. -12 - -- -14 - Continues massive. Medium dense to --dense. II -16 -5, 10, 12 (22) --End Test Boring@ 16½' -18 -No Caving No Groundwater -- -20 - SM S Geotecbnical Solutions, Inc. BORING LOG 1700 Aviara Parkway 6125 Paseo Del Norte, Carlsbad Carlsbad, California 92013 Job No. GI-12-14-34 PLATE 5 II SPT Sample D Bulk Sample 0 Driven Rings Date: January 16, 2015 Logged by: SJM DEPTH (ft) - 0 - -2 - - 4 - -6 - -8- -10 - -12 - -14 - -16 - -18- -20 - TP-1 SAMPLE DESCRIPTION Dump Fill (Uafl: Silty fine sand. Trace clay. Tan-brown color. Moist. Very loose. No evidence of benching 00 \ -fill placed atop sloping ground. ST-I Alluvium (Qal): Silty fine sand. Trace clay. Brown color. Local rust-colored staining. Blocky. Medium dense to dense. ST-\ End Test Pit@4½' No Caving No Groundwater uses Symbol SM J SM l Fleld Moisture (%) 9 Field Dry Density {pcf) 101.8 Relative Comp. (%) 82 TEST TRENCH LOGS SM S Geotechnical Solutions, Inc. 1700 Aviara Parkway Carlsbad, California 92013 6125 Paseo Del Norte, Carlsbad Saturation S('.4) 38 Job No. GI-1-15-01 PLATE6 V Sand Cone Test D Bulk Sample O Chunk Sample 0 Driven Rings Date: January 16, 2015 Logged by: SJM TP-2 Field Field Ory Saturation uses Density Relative DEPTH SAMPLE Molature Comp. S('.4) (ft) DESCRIPTION Symbol (%) (pcl) (%) - 0 - Oumg Fill {Uaf}: -- - 2 - Silty to clayey fine sand. Light brown color. \ Moist to very moist. Very loose. No evidence SM/SC I - -of benching. ST-1 J 17 104.8 81 78 0 - 4 - --Alluvium (Qal): - 6 -Silty fine sand. Locally clayey. Tan-brown color. Local rust-colored staining. Moist. SM/Sf) --Mediumdense. ST-1 0 18 102.6 80 78 -8- Very moist at 7'. Loose /soft to medium dense. / -10 -0 20 105.0 85 93 \ , --Formational RQck (Tsa): -12 -Siltstone-sandstone. Light grey color. SM™/ Weathered. Blocky. Dense. ST-3 -- -14 - End Test Pit@ 10½' -- No Caving -16 -No Groundwater - - -18 - -- -20 - SM S Geoteehnical Solutions, Inc. TEST TRENCH LOGS 1700 Aviara Parkway 6125 Paseo Del Norte, Carlsbad Carlsbad, California 92013 Job No. GI-1-15-01 PLATE 7 V Sand Cone Test □ Bulk Samole 0 Chunk Sample 0 Driven Rinas Date: January 16, 2015 Logged by: SJM TP-3 Relative Saturation DEPTH SAMPLE uses Symbol Field Moisture (%) Field Dry Density (pef) Comp. S(%) (ft) -0 - - 2 - - 4 - -6- - 8 - -10 - -12 - -14 - -16 - -18 - -20 - D 0 \ DESCRIPTION Dump Fill (Uaf): Silty to clayey fine sand. Red brown color. Moist. Loose.' ST-1 swsc Damp below 2'. Terrace Deposit (Qt): Fine to medium sandstone. Red brown color. Friable. Cemented. Medium dense to dense. ST-2 End Test Pit@ 6½' No Caving No Groundwater SP/ (%) 5 116.0 .94 If TEST TRENCH LOGS SM S Geotechnical Solutions, Inc. 1700 Aviara Parkway Carlsbad, California 92013 6125 Paseo Del Norte, Carlsbad Job No. GI-1-15-01 PLATES V Sand Cone Test □ Bulk Sample 0 Chunk Sample O Driven Rinos 32 Date: January 16, 2015 Logged by: SJM DEPTH (ft} - 0 - -2 - -4 - - 6 - -8- -10 - -12 - -14 - -16 - -18- -20 - TP-4 SAMPLE DESCRIPTION Dump Fill (Uaf): Silty fine sand. Trace clay. Red brown color. uses Symbol Moist to very moist. Loose. ST-1 sMI.SP 0 Terrace Deposit (Qt): \ Fine sandstone. Red brown color. Local rust-colored staining. Massive. Friable. Moderately cemented. Dense. ST-2.. End Test Pit@ 5½' No Caving No Groundwater .. / Field Moisture (%) 9 Field Dry Density (pcf) Relative Comp. (%) 106.6 86 TEST TRENCH LOGS SM S Geotechnical Solutions, Inc. 1700 Aviara Parkway Carlsbad, California 92013 6125 Paseo Del Norte, Carlsbad Saturation S(•A,) 43 Job No. GI-1-15-01 PLATE9 V Sand Cone Test □ Bulk Sample O Chunk Sample 0 Driven Rings Date: January 16, 2015 Logged by: SJM DEPTH (ft) -0 - -2 - -4 - -6 - TP-5 SAMPLE DESCRIPTION Dump Fill (Uaf): Silty to clayey sand. Brown -red brown color. uses SymbOI Moist near surface, damp below. Loose. swsc ST-l 0 Compacted at 4'. May be part of original fill (Caf). Damp. '""'1-------------------+---r/ Terrace Deposit (Qt): SP Field Moisture (o/,) 10 Field Ory Density (pef) Relative Comp. (%) 111.2 90 Saturation S('Ao) 55 _ 8-~-...... Fine sandstone. Light brown color. \ Weathered. Blocky. Dense. ST-2 I -10 - -12 - -14 - -16- -18 - -20 - End Test Pit@8' No Caving No Groundwater SM S Geotechnical Solutions, Inc. 1700 Aviara Parkway Carlsbad, California 92013 V Sand Cone Test □ Bulk Sample TEST TRENCH LOGS 6125 Paseo Del Norte, Carlsbad Job No. GI-1-15-01 PLATE 10 □ Chunk Sample O Driven Rings Date: January 16, 2015 DEPTH SAMPLE (ft) - 0 - - 2 - - 4 - TP-6 DESCRIPTION Dump Fill (Uaf): Silty to clayey fine sand. Pale brown color. uses Symbol Damp. Loose. ST-1 swsc \ Logged by: SJM Field Moisture (%) Field Ory Density (pcfJ Relative Comp. (%) Saturation SI%) / Alluvium (Qal): Silty to clayey sand. Tan-brown color. Local -6 ---rust-colored staining. Moist. Medium dense. □ SM/SC \ __ -i----+----+---'11 ST-1 -8 - -10 -0 Continues medium dense to dense. -12-/ II--+-----' End Test Pit@ 13½' No Caving -14 - -16- -18- -20 - No Groundwater SM S Geotechnical Solutions, Inc. 1700 Aviara Parkway Carlsbad, California 92013 V Sand Cone Test □ Bulk Sample 8 112.2 87 45 10 110.6 86 54 \ TEST TRENCH LOGS 6125 Paseo Del Norte, Carlsbad Job No. GI-1-15-01 PLATE 11 Q Chunk Sample 0 Driven Rinos AJPIPIEND ITX Design Maps Detailed Report IIIJSGS Design Maps Detailed Report ASCE 7-10 Standard (33.1178°N, 117.3184°W) Site Class D -"Stiff Soil", Risk Category I/II/III Section 11.4.1 -Mapped Acceleration Parameters Note: Ground motion values provided below are for the direction of maximum horizontal spectral response acceleration. They have been converted from corresponding geometric mean ground motions computed by the USGS by applying factors of 1.1 (to obtain Ss) and 1.3 (to obtain S1), Maps in the 2010 ASCE-7 Standard are provided for Site Class B. Adjustments for other Site Classes are made, as needed, in Section 11.4.3. From Figure 22-1 111 Ss = 1.154 g From Figure 22-2 r21 • 51 = 0.444 g Section 11.4.2 -Site Class The authority having jurisdiction (not the USGS), site-specific geotechnical data, and/or the default has classified the site as Site Class D, based on the site soil properties in accordance with Chapter 20. Table 20.3-1 Site Classification Site Class -Vs Nor Ha. -s. A. Hard Rock >S,000 ft/s N/A N/A _ .... ., ...... ----·· -· ---·-·· ---·--·----"-··----·---~----·-·-------------------------------------------·------··---------------------. B. Rock 2,500 to 5,000 ft/s N/A N/A Page 1 of 6 ------------·-·-_____ , -·--·---· . ··---·--· ·--·-···-----·--·----~---·-------·-~ ---··--·-----·--·-· ------------------------·-·--·-------c. Very dense soil and soft rock 1,200 to 2,500 ft/s >50 >2,000 psf D. Stiff Soil E. Soft clay soil F. Soils requiring site response analysis in accordance with Section 21.1 600 to 1,200 ft/S <600 ft/S 15 to 50 <15 1,000 to 2,000 psf <1,000 psf Any profile with more than 10 ft of soil having the characteristics: • Plasticity index PI > 20, • Moisture content w .!= 40%, and • Undrained shear strength Su < 500 psf See Section 20.3.1 For SI: 1ft/s = 0.3048 m/s 11b/ft2 = 0.0479 kN/m2 htto://ehol-earthouake.cr.usgs.1.mv/designmaps/us/reoort.oho?temolate=minimal&latitude=3 ... 1/8/2015 ----------------------------------------------·-------·· - ' Desi,gn Maps Detailed Report Page 2 of 6 Section 11.4.3 -Site Coefficients and Risk-Targeted Maximum Considered Earthquake (MCER) Spectral Response Acceleration Parameters Site Class A B C D E F Site Class A B C D E F Table 11.4-1: Site Coefficient F. Mapped MCE "-Spectral Response Acceleration Parameter at Short Period Ss s 0.25 Ss = 0.50 Ss = 0.75 Ss = 1.00 0.8 0.8 0.8 0.8 1.0 1.0 1.0 1.0 1.2 1.2 1.1 1.0 1.6 1.4 1.2 1.1 2.5 1.7 1.2 0.9 See Section 11.4.7 of ASCE 7 Note: Use straght-line interpolation for intermediate values of Ss For Site Class = D and S. = 1.154 g, F. = 1.038 Table 11.4-2: Site Coefficient F. Ss:?: 1.25 0.8 1.0 1.0 1.0 0.9 Mapped MCE "-Spectral Response Acceleration Parameter at 1-s Period 51 $ 0.10 S1 = 0.20 s, = 0.30 s, = 0.40 s, ~ 0.50 0.8 0.8 0.8 0.8 0.8 1.0 1.0 1.0 1.0 1.0 1.7 1.6 1.5 1.4 1.3 2.4 2.0 1.8 1.6 1.5 3.5 3.2 2.8 2.4 2.4 See Section 11.4.7 of ASCE 7 Note: Use straight-line interpolation for intermediate values of s, For Site Class = D and S, = 0.444 g, F. = 1,556 htto://ehol-earthauake.cr.us2s.1wv/desi!lllIIlaos/us/reoort.ohn?temolate=minimal&latitude=3 ... 1/8/2015 Ihsign Maps Detailed Report Section 11.6 -Seismic Design Category Table 11.6-1 Seismic Design Category Based on Short Period Response Acceleration Parameter RISK CATEGORY VALUE OF Sos I or II III IV Sos< 0.167g A A A 0.167g :S Sos< 0.33g B B C 0.33g :S Sos < 0.50g C C D O.SOg :5 Sos D D D For Risk Category = I and SDS = 0.799 g, Seismic Design Category = D Table 11.6-2 Seismic Design Category Based on 1-5 Period Response Acceleration Parameter RISK CATEGORY VALUE OF So, I or II III IV S01 < 0.067g A A A 0.067g :5 S01 < 0.133g B B C 0.133g :S So, < 0.20g C C D 0.20g :S So, D D D For Risk Category = I and So, = 0.461 g, Seismic Design category = D Note: When S, is greater than or equal to 0. 75g, the Seismic Design Category is E for buildings in Risk Categories I, II, and III, and F for those in Risk Category IV, irrespective of the above. Seismic Design Category= "the more severe design category in accordance with Table 11.6-1 or 11.6-2" = D Note: See Section 11.6 for alternative approaches to calculating Seismic Design Category. References Page 6 of6 1. Figure 22-1: http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7_Figure_22-1.pdf 2. Figure 22-2: http://earthquake.usgs.gov/hazards/ design maps/ downloads/pdfs/201 0_ASCE-7 _Figu re_22-2 .pdf 3. Figure 22-12: http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/20l0_ASCE-7_Figure_22- 12.pdf 4. Figure 22-7: http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/20l0_ASCE-7_Figure_22-7.pdf 5. Figure 22-17: http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7 _Figure_22- 17 .pdf 6. Figure 22-18: http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7 _Figure_22- 18.pdf htto:/ /ehp 1-earthouake.cr. usgs. gov/ designrn.aos/us/reoort.oho ?temolate=minimal&latitude=3 ... l /8/2015