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CT 05-03; LINCOLN & OAK MIXED USE; PRELIMINARY GEOTECHNICAL EVALUATION; 2004-01-12
Ct5O7 PRELIMINARY GEOTECHNICAL EVALUATION 3112 LINCOLN STREET: CITY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA FOR MR. RUSSELL BENNETr; c/a KARNAK ARCHITECTURE AND PLANNING 2802 STATE STREET SUITE C : CARLSBAD, CALIFORNIA 92008 • z 0 W.O. 4147-A-SC JANUARY 12, 2004 • p 0 w • • • C!) .•. Geotechnical Coastale Geologic 0 Environmental 5741 Palmer Way • Carlsbad, California 92010 (760) 438-3155 FAX (760) 931-0915 January 14, 2004 W.O. 4147-A-SC Mr. Russell Bennett do Karnak Architecture and Planning 2802 State Street, Suite C Carlsbad, California 92008 Attention: Mr. Robert Richardson Subject: Preliminary Geotechnical Evaluation, 3112 Lincoln Street, Carlsbad, San Diego County, California I , Dear Mr. Richardson: . . I .In accordance with your request,. GeoSoils, Inc.(GSI) has- performed a preliminary' geotechnical evaluation of the subject site. The purpose of the study was to evaluate the onsite soils and geologic conditions and their effects on the proposed site development from a geotechnical viewpoint. 0 EXECUTIVE SUMMARY, Based an our review of the available data '(see Appendix A), field exploration, laboratory testing, and geologic and-engineering analysis, commercial/residential development of the property appears to be feasible from a; geotechnical viewpoint, provided the I recommendations presented in the text of this report are properly incorporated into the, design and construction of the project. The most significant elements of this study are summarized below: ' I . • ' The proposed development will consist of a three-story mixed use (commercial/apartments with parking and commercial on the ground floor)'structure, I - as well as underground utility improvements and driveways. Removals of all existing fill and/or backfill (utilities), topsoilicolluvium, and the upper I ' 1 to 2 feet of weathered terrace deposits are recommended. Removal depths are anticipated to be on the order of 3 to 4 feet in areas proposed for settlement-sensitive improvements. I I ' 0 ' • 0 ' ' The expansion potential of tested onsite soils is very low. Conventional foundations may be utilized for these soil conditions. At the time of this report, corrosion testing results had not been received from the lab for the subject site. An addendum report presenting those results will be provided when lab testing is complete. In general, and based upon the available data to date, groundwater is not expected to be a major factor in development of the site; however, perched water may occur during construction and/or after site development, and should be anticipated. Our evaluation indicates that the site has a very low potential for liquefaction: Therefore, no recommendations for mitigation are deemed necessary. Our evaluation indicates there are no known active faults crossing the site. The seismic acceleration values and design parameters provided herein should be considered during the design of the proposed development. Adverse geologic features that would preclude project feasibility were not encountered. : The recommendations presented in this report should be incorporated into the design and construction considerations of the project. Mr. Russell Bennett W.O. 4147A-SC FiIe:e:\wp9\4100\4147a.pge Page Two The opportunity to be of service is greatly appreciated. If you have any questions concerning this report or if we may be of further assistance, please do not hesitate to contact the undersigned. Respectfully submitted, çD GeoSoils, Inc. cc *.D0NAGO0LEY * No. 7571 Donna Gooley Project Geologist, RG 757 Reviewed by: NO. U40 John P. Franklin V Engineering Geologist ., DG/JPF/DWS/jk/jh Distribution: (3) Addressee (1) Mr. Russell Bennett &. ,. <• David W. Skelly Civil Engineer, RCE 47857 Mr. Russell Bennett W.O. 4147-A-SC Fi1e:e:\wp9\4100\4147a.pge Page Three I TABLE OF CONTENTS I SCOPE OF SERVICES ....................................................1 SITE CONDITIONS/PROPOSED DEVELOPMENT ................................1 I SITE EXPLORATION ............... .......................................1 REGIONAL GEOLOGY ....................................................4 SITE GEOLOGIC UNITS ................................................... 4 I Topsoil/Colluvium. ..................................................... 4 Quaternary-Age Terrace Deposits .......................................4 I FAULTING AND REGIONAL SEISMICITY .......................................5 Faulting.............................................................5 I Seismicity ...........................................................5 Seismic Shaking Parameters .........................................7 Seismic Hazards .....................................................8 GROUNDWATER ...........................................................8 I LABORATORY TESTING .....................................................9 General..............................................................9 Classification ........................................................9 I Moisture-Density Relations . ........................................ .. 9 Laboratory Standard ...................................................9 I Expansion Potential .....................................................9 Direct.Shear Test ....................................................10 Corrosion/Sulfate Testing ............................................10 I CONCLUSIONS ...........................................................10 I EARTHWORK CONSTRUCTION RECOMMENDATIONS .........................10 General............................................................10 Site Preparation ....................................................11 I . Removals (Unsuitable Surficial Materials) ................................11 Fill Placement ....................................................11 I Transitions/Overexcavation ..........................................12 RECOMMENDATIONS - FOUNDATIONS .....................................12 Preliminary Foundation Design ...................................... .12 I --Design .............................................................12 Foundation Settlement ..................................................13 I Footing Setbacks ........................................................13 Construction .......................................................13 I . Very Low Expansion Potential (E.l. 0 to 20) ........................13 . . UTILITIES . 14 WALL DESIGN PARAMETERS ..............................................15 Conventional Retaining Walls .........................................15 Restrained Walls ............................................... 15 Cantilevered Walls ............................................15 Retaining Wall BackfIl and Drainage .............................16 Wall/Retaining Wall Footing Transitions ................................16 DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS ........................20 DEVELOPMENT CRITERIA ...............................................22 Drainage.........................................................22 Erosion Control .....................................................22 Landscape Maintenance ....................................................22 Gutters and Downspouts ..................................................23 Subsurface and Surface Water .........................................23 Site Improvements ...................................................23 Tile Flooring ......................................................24 Additional Grading ...................................................24 Footing Trench Excavation ...........................................24 Trenching .............................24 Utility Trench Backfill ...................................................24 SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING ........................25 OTHER DESIGN PROFESSIONALS/CONSULTANTS 26 PLAN REVIEW ..........................................................26 LIMITATIONS ............................................................26 Mr. Russell Bennett . . Table of Contents Fite:e:\wp9\4100\4147a.pge . . . . . Page ii 1 I . FIGURES: . . Figure 1 - Site Location Map 2 . Figure 2- Boring Location Map .......................................3 I Figure 3- California Fault Map .......................................... 6 Detail.1 -Typical-Retaining Wall backfill and Drainage Detail . ...........17 I . Detail 2- Retaining Wall Backfill and Subdrain detail Geotextile Drain .......18 ...........19 . Detail 3- Retaining Wall and Subdrain Detail Clean Sand Backfill I ATTACHMENTS: . ,. . . Appendix A - References ..................Rear of Text Appendix B - Boring Logs ..................................Rear of Text I Appendix C - Seismics .........................................Rear of Text Appendix D General EarthWork - and Grading Guidelines .........Rear of Text I I I I I I I . I I I I Mr. Russell Bennett . . Table of Contents F1e:e:wp9\41OO\4147a.pge.. . . . . .. Page iii I .. . .. S . S.. I I PRELIMINARY GEOTECHNIAL EVALUATION 3112 LINCOLN STREET CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA I . SCOPE OF SERVICES The scope of our services has included the following: I 1. Review of the available geologic literature for the site (see Appendix A). Geologic site reconnaissance, subsurface exploration, sampling and mapping. Appropriate laboratory testing of representative soil samples. 4 General areal seismicity evaluation 5. Engineering and geologic analysis of data collected. 6. Preparation of this report and accompaniments. . I . SITE CONDITIONS/PROPOSED DEVELOPMENT The property consists of a rectangular, relatively flat property, located at the southeast I .corner of the intersection of Oak Avenue and Lincoln Street, in the City of Carlsbad, San Diego County, California (see Figure 1, Site Location Map). A single-family residence occupies the property. The project area is located approximately 50 feet above Mean Sea • I Level (MSL). Site development is anticipated to consist of preparing the property for the construction of a three-story mixed use (commercial/apartments with parking and. commercial on the ground floor) structure, as well as underground utility improvements and I associated driveways. Building loads are assumed to be typical for this type of relatively light construction. It is anticipated that sewage disposal will be tied into the regional municipal system. The need for import soils is unknown. I . •• . • SITE EXPLORATION Surface observations and subsurface exploration were performed on December 27,2003, .I • by a representative of this office. A survey of line and grade for the subject site was not conducted by this firm at the time of our site reconnaissance. Near-surface soil conditions were explored with three hand-auger borings to evaluate near-surface soil and geologic I conditions. The approdmate location of each boring is shown on the Boring Location Map (see Figure 2). Boring Logs are presented in Appendix B. •. . I I . . . • • • . . • 3-D TopoQuadi Copyright 0 1999 DeLorine Yannouth, ME 04096 Map: San Luis Rey Quadrangle, California--San Diego Co., 7.5 Minute Series (Topographic), 1968 (photo revised 1.75), by USGS, 1"2000' I I I I I I I I I I I I I I I I I I I Base Map: The Thomas Guide, San Diego County Street Guide and Directory, 2002 Edition, by Thomas Bros. Maps, page 1106, 1"1/2 mile Reproduced with permission granted by Thomas Bros. Maps. TIs map Is copyrighted by Thomas Bros. Maps. It Is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without permission. All rights reserved. .0001 0 4147-A-SC SITE LOCATION MAP Figure lj B-3. a), a)' . >1 1 A B-2 I Lincoln Street...k.... I . •PJVESIDE CO. LEGEND SANÔIEGOCO BORING LOCATION B- 3 Approximate location of exploratory MAP-' Figure 2 hand auger boring cj. 4147ASC iATE 1/04 SCALE Sca1e ..... ..... REGIONAL GEOLOGY The subject property is located within a prominent natural geomorphic province in southwestern California known as the Peninsular Ranges. It is characterized by steep, elongated mountain ranges and valleys that trend northwesterly. The mountain ranges are underlain by basement rocks consisting of pre-Cretaceous metasedimentary rocks, Jurassic metavolcanic rocks, and Cretaceous plutonic rocks of the southern California batholith. . In the San Diego County region, deposition occurred during the Cretaceous Period of the Cenozoic Era in the continental margin of a forearc basin. Sediments, derived from Cretaceous-age plutonic rocks and Jurassic-age volcanic rocks, were deposited into the narrow, steep, coastal plain and continental margin of the basin. These rocks have been uplifted, eroded and deeply incised. During early Pleistocene time, a broad coastal plain was developed from the deposition of marine terrace deposits. During mid to late . Pleistocene time, this plain was uplifted, eroded and incised. Alluvial deposits have since filled the lower valleys, and young marine sediments are currently being deposited/eroded within coastal and beach areas. SITE GEOLOGIC UNITS I The site geologic units encountered during our subsurface investigation and site reconnaissance included topsoil/colluvium and terrace deposits. The earth materials are generally described below, from the youngest to the oldest. I Topsoil/Colluvium I Topsoil/collüvium, consisting of dark brown, moist, loose silty sand, approximately 1/2 to 1 foot thick, was observed mantling, the site. These soils are considered potentially. compressible in their existing state and will require removal during any future grading within the site, if settlement-sensitive improvements are proposed in those areas. The earth materials can be reused as compacted fill, provided deleterious material has been. I removed. . . Quaternary-Age Terrace Deposits . I Terrace deposits were observed to Underlie the site and consist generally of massive, medium dense to dense, with depth, silty sands. These deposits are generally red brown I in color, and moist. The upper two to three feet of these materials are generally weathered and considered unsuitable for structural support in their present condition and should. be removed and recompacted, should settlement-sensitive improvements be proposed within I their influence. . Mr. Russell Bennett W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad . . . . January 14, 2004 I Fi1e:e:\wp9\4100\4147a.pge . . . Page 4 III I FAULTING AND REGIONAL SEISMICITY Faulting The site is situated in a region of active as well as potentially-active faults. Our review indicates that there are no known active faults crossing the site within the areas proposed for development (Jennings, 1994), and the site is notwithin an Earthquake Fault Zone (Hart and Bryant, 1997). There are a number of faults in the southern California area that are considered active and would have an effect on the site in the form of ground shaking, should they be the source of an earthquake (Figure 3). These faults include-but are not limited to-the San Andreas fault, the San Jacinto fault, the Elsinore fault, the Coronado Bank fault zone, and the Newport-Inglewood -. Rose Canyon fault zone. The possibility of ground acceleration or shaking at the site may be considered as approximately similar to the southern California region as a whole. The following table lists the major faults and fault zones in southern California that could have a significant effect on the site should they experience significant activity. IT ABBREVlATEDFAULTNAME kA.pRoxlMATE:D]TANcEMlLEs(KM)t! Coronado Bank- Agua Blanca 20.8(33.5) Elsinore - Temecula 24.5(39.4) Newport-Inglewood-Offshore 5.0 (8.1) Rose Canyon 4.8 (7.8) Elsinore - Julian 24.7(39.8) - Seismicity The acceleration-attenuation relations of Sadigh, et al. (1997) Horizontal Soil, Bozorgnia, Campbell and Niazi (1999) Horizontal-Soft Rock-Correlation and Campbell, and Bozorgnia (1997 Rev.) Horizontal-Soil have been incorporated into EQFAULT (Blake, 2000a). For this study, peak horizontal ground accelerations anticipated at the site were determined based on the random mean plus 1 - sigma attenuation curve and mean attenuation curve developed by Joyner and Boore (1982a and 1982b), Bozorgnia, Campbell, and Niazi (1999), and Campbell and Bozorgnia (1997). EQFAULT is a computer program by Thomas F. Blake (2600a), which performs deterministiá seismic hazard analyses using up to 150 digitized California faults as earthquake sources. Mr. Russell Bennett • • - W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad • • • January 14, 2004 File:e:\wp9\4100\4147a.pge • • Page 5 I I . I 1100 1000 900 800 700 600 500 400 1. 300 200 I 00 I. 0 I -100 I. -400 -300 -200 -100 W.O. 4147-A-SC I 0 100 200 300 400 500 600 CALIFORNIA FAULT MAP 3112Lincohi Figure 3 The program estimates the closest distance between each fault and a given site. If a fault is found to be within a user-selected radius, the program estimates peak horizontal ground acceleration that may occur at the site from an upper bound ("maximum credible") earthquake on that fault. Site acceleration (g) is computed by one of many user-selected acceleration-attenuation relations that are contained in EQFAULT. Based on the EQFAULT program, peak horizontal ground accelerations from an upper bound event at the site may be on the order of 0.54g to 0.679. Historical site seismicity was evaluated with the acceleration-attenuation relations of Campbell and Bozorgnia (1997 Revised) Soft Rock and the computer program EQSEARCH (Blake, 2000b). This program performs a search of the historical earthquake records for magnitude 5.0 to 9.0 seismic events within a 100-mile radius, between the years 1800 to 2002. Based on the selected acceleration-attenuation relationship, a peak horizontal ground acceleration is estimated, which may have effected the site during the specific event listed. Based on the available data and the attenuation relationship used, the estimated maximum (peak) site acceleration during the period 1800 to 2002 was 0.27g. Site specific probability of exceeding various peak horizontal ground accelerations and a seismic recurrence curve are also estimated/generated from the historical data. Computer printouts of pertinent portions of the EQSEARCH program are presented in Appendix C. A probabilistic seismic hazards analyses was performed using FRISKSP (Blake, 2000c) which models earthquake sources as three-dimensional planes and evaluates the site specific probabilities of exceedance for given peak acceleration levels or pseudo-relative velocity levels.. Based on a review of these data, and considering the relative seismic activity of the southern California region, a peak horizontal ground acceleration of 0.34g was calculated. This value was chosen as it corresponds to a 10 percent probability of exceedance in 50. years (or a 475-year return period). Seismic Shaking Parameters Based on the site conditions, Chapter 16 of the Uniform Building Code ([UBC], International Conference of Building Officials [lCBQ], 1997), the following seismic parameters are provided. Seismic zone (per Figure 162*) . . . 4 Seismic Zone Factor (per Table 161*) 0.40 Soil Profile Type (per Table 16-J*) . S0 Seismic Coefficient Ca (per Table 16Q*) 0.44 Na Seismic Coefficient C (per Table 16R*) 0.64 N Near Source Factor Na (per Table 16-S*) 1.0 Mr. Russell Bennett W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad January 14, 2004 File:e:\wp9\4100\4147a.pge . . . Page 7 Near Source Factor N (per Table 16-T*)* 1.1 Seismic Source Type (per Table 16U*) - B Distance to Seismic Source 4.8mi. (7.8 km) Upper Bound EárthqUake (ROsé Can.yön) M 6.9 * Figure and table references from Chapter 16 of the UBC (ICBO, 1997). Seismic Hazards The following list includes other seismic-related hazards that have been considered during our evaluation of the site. The hazards listed are considered negligible and/or completely mitigated as a result of site lobation, soil characteristics and typical site development procedures: . . . . Liquefaction. I Tsunami . Sieche . I . . Dynamic Settlement Surface Fault Rupture Ground Lurching or Shallow Ground Rupture It is important to keep in perspective that in the event of a maximum probable or credible (upper bound) earthquake occurring on any of the nearby major faults, strong ground shaking would occur in the subject site's general area. Potential damage to any structure (s) would likely be greatest from the vibrations and impelling force caused by the inertia of a structure's mass, than from those induced by the hazards considered above. This potential would be no greater than that for other existing structures and improvements in the immediate vicinity. . GROUNDWATER Subsurface water was not encountered within the property during field work performed in preparation of this report. Subsurface water is, not anticipated to adversely affect site development, provided that the recommendations contained in this report are incorporated into final design and construction. These observations reflect site conditions at the time of our investigation and do not preclude future changes in local groundwater conditions from excessive irrigation, precipitation, or that were not obvious, at the time of our investigation. Regional groundwater is estimated.to be at least 50 feet in depth, belowthe site. I Mr. Russell Bennett . . . . W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad ' January 14, 2004 I File:e:\wp9\4100\4147a.pge . . . . ' Page 8 . . I I . Seeps, springs, or other indications of a high groundwater level were not noted on the subject property during the time of our field investigation. However, seepage may occur I . locally (as the result of heavy precipitation or irrigation) in areas where any fill soils overlie terrace deposits. Such conditions may occur during grading or after the site is developed, and shOuld be anticipated. LABORATORY TESTING . I . General . . . I Laboratory tests were performed on representative samples of the onsite earth materials in order to evaluate their physical characteristics. The test procedures used and results obtained are presented below. .. - Classification . . I Soils were classified visually according to the Unified Soils Classification System(USCS). The soil classifications are shown on the Boring Logs in Appendix B. 1 . Moisture-Density Relations . I .The field moisture contents and dry unit weights were determined for a selected undisturbed sample in the laboratory. The dry unit weight was determined in pounds per cubic foot (pcf), and the field moisture content was determined as a percentage. of the dry I weight. The results of these tests are shown on the Boring Logs in Appendix B. I Laboratory Standard . The maximum dry density and optimum moisture content was determined forthe major soil type encountered in the borings. The laboratory standard used was ASTM D-1 557. The I moisture-density relationship obtained for this soil is shown below: BORI NG AND 11!i M DRY LOPTIMUM MOISTURE t 1— SOILTYPENid MI MAXIMU IftY .:ó'djiEN.. SILTY SAND, Red Brown I B-i @2-3 I 131.5 9.5 . I I Expansion Potential . . . . . . . I . Expansion testing was performed on representative samples of site soil in accordance with UBC Standard 18-2. The results of expansion testing are presented in the following table. Mr. Russell Bennett . . W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad . . January 14, 2004 I. . File:e:\wp9\4100\4147a.pge . .. . . . Page 9 fw I I 4ri1EiLifl! 1 ]1'71 1I1]L!iJflfl ::.ii1i11 - LOCATION EXPANSION INDEX ii EXPANSION POTENTIAL j]i I B-i @ 24 I 0 I Very Law Direct Shear Test Sheartesting was performed on a representative, undisturbed sample of site soil in general accordance with ASTM Test Method D-3080 in a Direct Shear Machine of the strain control type. The shear test result is as follows: tOCATION ill:; j1!j 11iCollESIONII, FRlCTION ANGLE Ijii!I-COHESION 12 ON ANGLE Jil' IiJt(ps1i11 ii!i J1 J (pii1 eft L-B-1@ 2-3' 225 38 225 { 35 Corrosion/Sulfate Testing Laboratory test results for soluble sulfates, pH, and corrosion to metals have not been received as of the date of this report. Testing will be presented as an addendum upon receipt of the results. Additional testing of site materials is recommended when proposed grading is complete to further evaluate the findings. CONCLUSIONS Based upon Our site reconnaissance, subsurface exploration, and laboratory test results, it is our opinion that the subject site appears suitable for the proposed. commercial/residential development. The following recommendations should be incorporated into the construction details. EARTHWORK CONSTRUCTION RECOMMENDATIONS General All grading should conform to the guidelines presented in Appendix Chapter A33 of the UBC, the requirements of the City, and the Grading Guidelines presented in Appendix D, exceptwhere specifically superceded in the text of this report. Prior to grading, a GSI Mr. Russell Bennett .. . W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad . . . January. 14, 2004 File:e:\wp9\4100\4147a.pge . . . Page 10 I I representative should be present at the preconstructiOn meeting. to provide additional grading guidelines, if needed, and review the earthwork schedule. I During earthwork construction all site preparation and the general grading procedures of the, contractor should be observed and the fill selectively tested by a representative (s) of GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed by this office and if warranted, modified and/or additional recommendations will be offered. All applicable requirements of local and national construction and general industry safety I orders, the Occupational Safety and Health Act, and the Construction Safety Act should be met. I Site Preparation Debris, vegetation, existing structures, and other deleterious material should be removed I . from the building area prior to the start of construction. Sloping areas to receive fill should be properly benched in accordance with current industry standards of practice and I guidelines specified in the UBC. . Removals (Unsuitable Surficial Materials) Due to the relatively loose condition of topsoil and weathered terrace deposits, these materials should be removed and recompacted in areas proposed for settlement-sensitive I structures or areas to receive compacted fill. At this time, removal depths on the order of 3 to 4 feet (including topsoil and weathered terrace deposits) below existing grade should be anticipated throughout a majority of the site; however, locally deeper removals cannot I .be precluded. Removals should be completed below a 1:1 projection down and away from 'the edge of any settlement-sensitive improvements and/or limits of proposed fill. Once removals are completed, the exposed bottom should be reprocessed and compacted to I 90 percent relative compaction. I . Fill Placement Subsequent to ground preparation, onsite soils may be placed in thin (±6-inch) lifts, cleaned of vegetation and debris, brought to a least optimum moisture content, and I compacted to achieve a minimum relative compaction of 90 percent. If soil importation is planned, a sample of the soil import should be evaluated by this office prior to importing, I in order to assure compatibility with the onsite site soils and the recommendations presented in this report. Import soils for a fill cap should be low 'expansive (Expansion Index [E.l.] less than .50). The. use of subdrains at the bottom of the fill cap may be I .necessary, and subsequently recommended based on compatibility with onsite soils and proximity and/or suitability of an outlet. . . I , . I Mr. Russell Bennett , . . , . . W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad , . . . . January 14, 2004 I . File:e:\wp9\4100\4147a.pge . . . , . Page 11 r_ , . Transitions/Overexcavation Cut portions of cut/fill transition pads should be overexcavated a minimum 3 feet below pad grade. Areas with planned fills less than 3 feet should be overexcavated in order to provide a minimum fill thickness of 3 feet, on a preliminary basis. Where the ratio of maximum to minimum fill thickness below a given structure exceeds 3:1, overexcavation should be completed to reduce this ratio to 3:1, or less. RECOMMENDATIONS -FOUNDATIONS Preliminary Foundation Design In the event that the information concerning the proposed development plans are not correct or any changes in the design, location, or loading conditions of the proposed structures are made, the conclusions and recommendations contained in this report are for the subject site only and 'shall not be considered valid unless the changes are reviewed ,and conclusions of this report are,modified or approved in writing by this office. The information and recommendations presented in this section are considered minimums and are not meant to supercede design(s) by the project structural engineer or civil engineer specializing' in structural design. Upon request, GSI could provide additional consultation regarding soil parameters ' as related to foundation design. They are considered preliminary recommendations for proposed construction, in consideration of our field investigation, and laboratory testing and engineering analysis. Our review, field work, and recent and previous laboratory testing indicates that onsite soils have avery low expansion potential range (E.l. 0 t 20).. Preliminary recommendations for foundation' design and construction are, presented below. , Final foundation recommendations should be provided at the conclusion of grading based on laboratory testing of fill materials exposed at finish grade: Design 1. An allowable soil bearing pressure of 1,500 psf may be used for the design of continuous footings with a minimum width of 12 inches and depth of 12 inches and I ' for design of isolated pad footings 24 inches square and 24 inches deep founded entirely into compacted fill or competent fbrmational material and connected by grade beam or tie beam in at least one direction. This value may be increased by I ' 20 percent for each additional 12 inches in depth to a maximum value of 2,500 psf. 2. An allowable coefficient of friction between concrete and compacted fill or bedrock I of 0.35 may be used with the deadload forces. , I ' Mr. Russell Bennett '' W.O. 4147-A-SC 3112 Uricoln Street, Carlsbad ' ' , , January 14, 2004 I File:e:\wp9\4100\4147apge ' ' ' ' ' ' , Page 12 ' I 3. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 4. Passive earth pressure may be computed as an equivalent fluid having a density of 250 pounds per cubic foot (pcf) with a maximum earth pressure of 2,500 psf. I 5. All footings should maintain a minimum 7-foot horizontal distance between the base of the footing and any adjacent descending slope, and minimally comply with the I guidelines depicted on Figure No. 18-I-1 of the UBC (current edition). I Foundation Settlement . . Foundations systems should be designed to accommodate a worst case differential Settlement of 1 inch in a 40-foot span. I Footing Setbacks All footings should maintain a minimum 7-foot horizontal setback from the base. of .the footing to any descending slope. This distance is measured from the footing face at the .I bearing elevation Footings should maintain a minimum horizontal setback of H/3 (H =slope height) from the base of the footing to the descending slope face and no lOss than 7 feet nor need to be greater than 40 feet. Footings adjacent to unlined drainage swales I .should be deepened to a minimum of 6 inches below the invert of the adjacent unlined swale. Footings for structures adjacent to retaining walls should be deepened so as to extend below a 1:1. projection from the heel of the wall. Alternatively, walls may be I designed to accommodate structural loads from buildings or appurtenances as described in the retaining wall section of this report I Construction . .. . . .. . . The following foundation construction re.commendatións are presented as a minimum .I criteria from a soils engineering standpoint. The onsite soils expansion potentials are generally very low(E.L 0 to 20). Recommendations for very low expansive soil conditions I are presented herein. . Recommendations by the projeôt's design.structural engineer or architect, which may I exceed the soils engineers recommendations, should take precedence over the following minimum requirements. Final foundation design will be provided based on the expansion potential of the near surface soils encountered during grading. I Very Low Expansion Potential (El. 0 to 20) •. • I .1. Exterior and interior footings should be founded ataminimum depth of 12 inchesfor one-story floor loads, 18 inches for two-story floor loads, and 24 inches for I .. Mr. Russell Bennett . • . . • W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad . . : . . January 14, 2004 I . File:e:\wp9\4100\4147apge . • . . . . . . Page .13 I I . three-story floor loads, below the lowest adjacent ground surface. Isolated column and panel pads or wall footings should be founded at, a minimum depth of 24 inches. All footings should be reinforced with two No. 4 reinforcing bars, one placed near the top and one placed near the bottom of the footing. Footing widths should be as indicated in the UBC (ICBO, 1997); width of 12 inches for. one-story I loads, 15 inches for two-story loads, and 18 inches for three-story loads. 2. A grade beam, reinforced as above, and at least 12 inches wide should be provided .I across large (e.g., doorways) entrances. The base of the grade beam should be at the same elevation as the bottom of adjoining footings. Isolated, exterior square footings should be tied .within the main foundation in at least one direction with a I grade beam. . . Residential concrete slabs, where moisture condensation is undesirable, should be I . underlain with a vapor barrier consisting of a minimum of 10 mil polyvinyl chloride or equivalent membrane with all laps sealed. This membrane should be covered above and below with a minimum of 2 inches of sand (total of 4 inches) to aid in I uniform curing of the concrete and to protect the membrane from puncture.. Residential concrete slabs should be a minimum of 5 inches thick, and should be reinforced with No. 3 reinforcing barat 18 inches on center in both directions. All slab. reinforcement should be supported to ensure placement near the vertical midpoint of the concrete. "Hooking" of reinforcement is not considered an acceptable method of positioning the reinforcement. . I S. .Residential garage slabs should be a. minimum of 5 in thick and should be reinforced as above and poured separately from the structural footings and quartered with expansion joints or saw cuts. A positive separation from the footings I should be maintained. with expansion joint material to permit relative movement. 6. . Presaturation is not required for these soil conditions. The moisture content of the I . subgrade soils however, should be equal to or greater than optimum, moisture content in the slab areas prior to the placement to visqueen. PriOr to placing visqueen or reinforcement, soil moistures should be verified by this office withih 72 I . hours of pouring slabs. UTILITIES . . Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. Due to the potential for differential settlement, air conditioning (NC) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with . Mr. Russell Bennett •. . . W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad . . . . January 14, 2004 FiIe:e:\wp9\4100\4147a.pge . . . Page 14 flexible couplings for plumbing and electrical lines. NC waste waterlines should be drained to a suitable outlet. WALL DESIGN PARAMETERS Conventional Retaining Walls The design parameters provided below assume that either non expansive soils (Class. 2 permeable filter material or Class 3 aggregate base) or native materials (up to and including low expansion potential) are used to backfill any retaining walls. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the plans. Building walls, below grade, should be water-proofed or damp-proofed, depending on the degree of moisture protection desired. The foundation system for the proposed retaining walls should be designed in accordance with the recommendations presented in this and preceding sections of this report, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches) and should be 24 inches in width. There should be no increase in bearing for footing width. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid pressure (EFP) of 65 pcf, plus any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 10 feet high. Design parameters for walls less than 3 feet in height maybe superceded by City and/or County standard design. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. .An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions due to traffic, structures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. . . I . Mr. Russell Bennett 3112 Uncoln Street, Carlsbad FiIe:e:\wp9\4100\4147a.pge W.0; 4147-A-SC January 14, 2004 Page 15 IRETAINED MATERIAL'S FLUID WEIGHT P C'FJ 1 FLUID WEIGHT P C F .'(HORlZONTAL:VERTICAL) :(SELEC IF -. 4 T'BACKFILL)t ..' NATlVEBACKFILL)i Level* 35 45 2to1 50 ' 60 * Level backfill behind a retaining wall is defined as compacted earth materials, properly drained, without a slope for a distance of 2H behind the wall. Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1, 2, and 3, present the back drainage options. discussed below. Backdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in either Class 2-permeable filter material or.1/2-inch to 3/4-inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). For low expansive backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the walls and upward at least 1 foot. For native backfill that has up to medium expansion potential, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and, confined areas, (panel) drainage behind the wall may be constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an expansion index (E.l.) 'potential of greater than 90 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than ± 100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes in walls higher than 2 feet should not be considered. The surface of the backfill should be sealed by pavement or the top 18 inches compactedwith native soil.(E.l. <90). Proper surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the ,back of 'all retaining structures. The use of a waterstop should be considered for all concrete and masonry joints. Wall/Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: I Mr. Russell Bennett ' ' ' ' W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad ' ' ' , 'January 14, 2004 File:e:\wp94100\4147a.pge ' . Page 16 DE1L41L.' N T., S.. Native BackfiU Provide surface drainage Slope or Level ±12' Water proofing membrane (optional) ® \/eephole Finished surface Native Backf ill 1'2t ' F Rock JJ -® Filter fabric 1 /4 or flatter Native Backfill ,-® Pipe) WATER PROOFING MEMBRANE ,(optional) Liquid boot or approved equivalent. RUCK 3/4 to 1-1/2' (Inches) rock, ® FILTER FABRIC% Mlrafi 140N or approved equivalent place fabric flap behind core. ®PIPE' .' 4' (Inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1% gradient to proper outlet point. ® WEEPHOLE' ' ' Minimum 2' (Inches) diameter placed at 20' (feet) on centers along the wall, and 3.' (inches) above finIshed surface. TYPICAL RETAINING WALL BACKFILL AND DRAINAGE DETAIL DETAIL 1' Geotechnical • Geologic. Environmental DETAIL N.T.S. Provide surface drainage Native Backfill Slope or Level 6' CD Water proofing membrane (optional)) © Weephole Finished surface Native Backfill ...® Drain . or flater ®Filter fabric ,—(Pipe 4 iJ WATER PROOFING MEMBRANE (optional)' Liquid boot or approved equivalent ® DRAIN' Mlradralti 6000 or J-drain 200 or equivalent for non-waterproofed watts, Miraoiraln 6200 or J-droin 200 or equivalent for water proofed walls. . . FILTER FABRIC' . Mlrafi 140N or approved equivalent place fabric flap behind core. PIPE' . 4' (Inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1% gradient to proper outlet point. VEEPHOLE' . . . .. . .Minimum 2' (Inches) diameter placed at 20' (feet) on centers along the wall, and 3' (Inches) above finished surface. RETAINING WALL BACKFILL AND S.UBDRAIN DETAIL ,• GEOTEXTILE DRAIN DETAIL 2,1 Geotechnical • 3eologic • Environmental DETAIL N.T.S. Provide surface drainage (3 'v/eePhole fl _\J nished surface Native Backfill. Slope or Level _H/2 mm. //4or Water proving membrane (öptional) ter' eansand backfill Filter. fabric -®Rock Pipe - Heel width WATER PROOFING MEMBRANE (optional)' Liquid boot or approved equivalent. ® CLEAN SAND BACKFILLs Must have sand equivalent value of 30 or greaterj can be densified by water Jetting, FILTER FABRIC' Mirafi 140N or approved equivalent ® ROCK' . . 1 cubic foot per linear feet of pipe of 3/4 to 1-1/2' (Inches) rock ® PIPE' 4' (Inches) diameter perforated PVC. schedule 4.0 or approved alternative with minimum of 1% gradient to proper outlet point. ® VEEPHULE' Minimum 21 (Inches) diameter placed at 20' (feet) on centers along the wall, and 3' (inches) above finished surface. RETAINING WALL AND SUBDRAIN DETAIL CLEAN SAND BACKFILL DETAIL 3 Geotechniôal ° Geologic • Environmental I. a) A minimum, of a 2-foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. I b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints or crack control joints) such that a angular distortion of 1/360.for a distance of 2H on I either side of the transition may be accommodated Expansion joints should be sealed with a flexible, non-sh(nk grout. c) Embed the footings entirely into native formational material (i.e., deepened footings). If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. - DRIVEWAY. FLATWORK, AND OTHER IMPROVEMENTS I Some of the soil materials onsite may be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level• I . areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting'potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is I .recommended that the developer should notify any , homeowners or homeowners . association of this long-term potential for distress. To reduce the likelihood of distress, the I following recommendations are presented for all exterior flatwork on expansive soils: 1. The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points I above (or .125 percent of) the soils' optimum moisture content; to a depth of 18 inches below subgrade elevation. The moisture content of the subgrade should I be verified within 72 hours prior to pouring concrete. Concrete slabs should be cast over a relatively non-yielding surface, consisting of I a4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete The layer should wet-down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding. earth I materials. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and I .approaches should additionally have a thickened edge (12 inches) adjacent to all landscape areas, to help impede infiltration of landscape water under the slab. I •4. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate I Mr. Russell Bennett . . . . W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad. • •. . January 14, 2004 FiIe:e:\wp9\4100\4147a.pge . . . . . •. . . . Page 20 I I . . such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of control and/or I . expansion joints to accommodate anticipated concrete shrinkage and expansion. In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each I direction. The exterior slabs should be scored or saw cut, ½ to 3/ inches deep, often enough so that no section is greater than 10 feet by 10 feet. For sidewalks or narrow I . slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. I . No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression strength should be a minimum of 2,500 psi.. .I Driveways, sidewalks, and patio slabs adjacent to the house should be separated I .. from the house with thick expansion joint filler material. In areas directly -adjacent toa continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. . . I .7. Planters and walls should not be tied to the house. I . Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. I Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These .segments should be keyed or doweled together. I Utilities should be enclosed within a closed utilidor (vault) or designed with flexible to accommodate differential settlement and expansive soil conditions. I . connections Positive site.drain.age should be maintained at all times. Finish grade on the lots I . should provide a minimum of 1 to 2 percent fall to the street, as indicated he It should be kept in mind that drainage reversals could occur, including post-construction settlement, if relatively flat yard drainage gradients are not I . periodically maintained by the homeowner or homeowners association. Air conditioning (A/C) units should be supported by slabs that are incorporated into I . . the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. NC waste water lines should be drained to a suitable non-erosive outlet. . . . I Mr. Russell Bennett . . . . . .., .. W.O., 4147-A-SC. . 3112 Uncoln Street, Carlsbad . . . . January 14, 2004 File e \wp9\4100\4147a pge Page 21 I S 13. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed. Finishing and curing practices should be performed per the I .. Portland Cement AssOciation Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of soils, and fertilizers used on site. DEVELOPMENT CRITERIA I Drainage I Adequate lot surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations, hardscape, and slopes; Surface drainage should be sufflcientto prevent ponding of water anywhere on a lot, and especially nearstructures and I tops of slopes. Lot surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore; care should be taken that future I landscaping or construction activities do not create adverse drainage conditions Positive site drainage within lots and common areas should be provided and maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should I be directed away from foundations and not allowed to. pond and/or seep into the ground. In general, the area within 5 feet around a structure should slope away from the structure. We recommend that unpaved lawn and landscape areas have a minimum gradient of one I . percent sloping away from structures, and whenever possible, should be above adjacent paved areas. Consideration should be given to avoiding construction of planters adjacent to structures (buildings, pools, spas, etc.). Pad drainage should be directed toward the I street or other approved area(s). Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means may be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet from structures, or into a I .subsurface drainage, system.. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated.. Minimizing irrigation will.lessen' this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon I . request. . .. . . I Erosion Control S Cut and fill slopes will be subject to surficial erosion during and after grading. Onsite earth I .materials have moderate to high erosion potential. ,Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. Landscape Maintenance I Only the amount of irrigation necessary, to sustain plant life should be provided. Oyer-watering the landscape areas will adversely affect proposed site improvements. We I Mr. Russell Bennett . . ., ' W.O. 4147-A-SC 3112 Uncoln Street, Carlsbad . . ' : , . , January 14, 2004 I FiIe:e:\wp9\4100\4147a.pge' . S ' .. . . . Page 22 I would recommend that any proposed open-bottom planters adjacent to proposed structures be eliminated for.a minimum distance of 10 feet. As an alternative, closed-bottom type planters could be utilized. An outlet placed in the bottom of the planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided I' with a moisture barrier to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain the excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. Graded slope areas should be ' planted with drought resistant vegetation. Consideration should be given to the type of vegetation chosen and their potential effect upon' surface improvements (i.e., some trees will have an effect on concrete flatwork with their extensive root systems). From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils are, processed for the purpose, of adding amendments, they should be recompacted to 90 percent minimum relative compaction. ' Gutters and Downspouts As previously discussed in the drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures. If utilized, the downspouts should be drained into PVC äollector pipes or non-erosive devices that will carry the water away from the house. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint,, provided that positive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water Subsurface and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design, and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation,' rainfall, or other factors. Site Improvements ' ' I Recommendations for exterior concrete flatwork design and construction can be provided upon request. If in the future, any additional improvements (e.g.,' pools,' spas, etc.) are planned for the site, recommendations concerning the geological or geotechnical aspects .I of design and construction of said improvements could be provided upon request. This office should be notified in advance of any fill placement, grading of the site, 'or trench I ' Mr. Russell Bennett ' . ' ' W.O. 4147-A-SC 3112 Uncoln Street, Carlsbad ' ' ' ' January 14, 2004 I Fi1e:e:\wp9\4100\4147a.pge ' ' " . ' Page 23 bs I Ibackfllling after rough grading has been completed.. This includes any grading, utility trench, and retaining wall backfihls. . I Tile Flooring . Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small I cracks in a conventional slab may not be. significant. Therefore, the designer should consider additional steel reinforcement for concrete slabs-on-grade where tile will be I placed. The tile installer should consider installation methods that reduce possible cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between I tile and concrete slabs on grade. I .Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backlilling after rough grading has been completed. This includes I completion of grading in the street and parking areas and utility trench and retaining wall backlills. . . . I Footing Trench Excavation I All footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose of the observations is to verify that the excavations are made into the recommended bearing I material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of the subgradO materials would be recommended at that time. I :Footing trench spoil and any excess soils generated from utility trench excavations should I *be compacted to a minimum relative compaction of 90 percent, if not removed from the site. I Trenching. . . . Considering the nature of the onsite soils, it should be anticipated thatcaving or sloughing I .could be afactor in subsurface excavations and trenching. Shoring or excavating the trench walls at the angle of repose (typically 25 to 45 degrees) may be necessary and should be. anticipated. All excavations should be observed by one of our representatives and I minimally conform to CAL-OSHA and local safety codes. I .. Utility Trench Backfill .. . . ,. . 1. All interior utility trench backfill should be brought to at least 2 percent above I . optimum moisture content and then compacted to obtain a minimum relative . compaction of 90 percent of the laboratory standard. As an alternative for shallow I .(12-inch to 18-inch) under-slab trenches, sand having a sand equivalent value of Mr. Russell Bennett W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad • . . • • : • • January 14, 2004 I FiIe:e:\wp9\4100\4147a.pge • ,. . • . . . Page 24 . . 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to verify the desired results. Exterior trenches adjacent to, and within areas extending below a. 1:1 plane - projected from the outside bottom edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to verify the desired results. All trench excavations should conform to CAL-OSHA and local safety codes. Utilities crossing grade beams, perimeter beams, or footings should either pass below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations of the structural engineer. . SUMMARY OF RECOMMENDATIONS REGARDING. GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and/or testing be performed by GSI at each of the following construction stages: During grading/recertification. . After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. Prior to pouring any slabs or flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor barriers (i.e.,visqueen, etc.). During retaining wall subdrain installation, prior to backfill placement. During placement of backfill for area draini interior plumbing, utility line trenches, and retaining wall backfill. . . During slope construction/repair. When. any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed. . .. . Mr. Russell Bennett . . . W.O. 4147-A-SE 3112 Uncbln Street, Carlsbad . . . . . . . .. January 14, 2004 FUe:e:\wp9\4100\4147a.pge . . . Page 25 1w . I I I I I I I. 1 I I I I I I I I I I I A' report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in ordèr,to provide concise and clear documentation of site work, and/or to comply with code requirements.. OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into, all their respective plans, and by explicit reference, make this 'report part of their project plans. PLAN REVIEW Final project plans should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and/or further geotechnical studies may be warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice,' and no warranty is expressed or implied. Standards of practice are'subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of th,is report constitutes an agreement and .consent by the user to all the limitations outlined' above, notwithstanding any other agreements that may, be in place. In addition, this report may be, subject to review by the controlling authorities. I Mr. Russell Bennett ' W.O. 4147-A-SC 3112 Lincoln Street, Carlsbad . . ' .. January 14, 2604 I ' FOe:e:\wp9\4100\41 7a.pge . . . ' , ' ' ' , , Page 26 w_ ' ' .1. I I I. I I I •.. .1 I I. I.. I. I. I . I .' I I I . S APPENDIXA. REFERENCES I APPENDIX A REFERENCES I Blake, T.F., 2000a, EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3-D fault sources; Windows 95/98 version. I , 2000b, EQSEARCH, A computer program for the estimation of peak horizontal acceleration from California historical earthquake catalogs; Updated to June, 2003, I Windows 95/98 version. 2000c, FRISKSP, A computer program for the probabilistic estimation of peak . acceleration and uniform hazard spectra using 3-D faults as earthquake sources; Windows 95/98 version. . Bozorgnia, Y., Campbell, K.W., and Niazi, M., 1999, Vertical ground motion: Characteristics, relationship with horizontal component, and building-code implications; Proceedings of the SM1P99 seminar on utilization of strong-motion data, September, I 15, Oakland, pp. 23-49.- Campbell, K.W. and Bozorgnia, V., 1994, Near-sôurcé attenuation of peak horizontal. I acceleration from worldwide accelerograms recorded from 1957 to 1993;. Proceedings, Fifth U.S. National Conference on Earthquake Engineering, volume Ill, I .Earthquake Engineering Research Institute, pp 292-293. Hart, E.W. and Bryant,-W.A., 1997, Fault-rupture hazard zones in California, Aiquist-Priolo earthquake fault zoning act with index to earthquake fault zones maps; California I Division of Mines and Geology Special Publication 42, with Supplements 1 and 2, 1999. • I • International Conference of building officials, 1997, Uniform building code: Whittier, California, vol. 1, 2, and 3. • I Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California Division of Mines and Geology, map sheet no. 6, scale 1:750,000. I . Joyner, W. B, and Boore, D.M.,.1 982a, Estimation of response-spectral values as functions • of magnitude, distance and site conditions, in eds., Johnson, J.A.., Campbell, K.W., and Blake, T.F.: AEG Short Course, Seismic Hazard Analysis, June 1.8,1994.- 1 982b, Prediction of earthquake response spectra, U.S. Geological Survey Open-File Report 82-977, 1 6p. •.' • .' • Kennedy, M.P. and Tan S.S., 1996, Geologic maps of the northwest part of San 'Diego I • County, California, Division of Mines and Geology, plate 1, scale 1:24,000. • • I Petersen, Mark D., Bryant, W.A., and Cramer, C.H. 1996, Interim table of fault parameters used by the California Division of Mines and Geology to compile the probabilistic seismic hazard maps of California. Sadigh, K., Chang, C.-Y., Egan, J.A., Makdisi, F., and Youngs, R.R., 1997, Attenuation - relations for shallow crustal earthquakes based on California strong motion data, Seismological Research Letters, Vol. 68, No. 1, pp. 180189. : Sadigh, K., Egan, J., and Youngs, A.; 1987, Predictive ground motion equations reported in Joyner, W.B., and Boore, D.M., 1988, "Measurement, Characterization, and Prediction of Strong Ground Motion," in Earthquake Engineering and Soil Dynamics II, Recent Advances in Ground Motion Evaluation, Von Thun, J.L., ed.: American Society of Civil'Engineers Geotechnical Special Publication No. 20, pp.*43-102. Sowers and Sowers, 1970, Unified soil classification system (After U S. Waterways Experiment Station and ASTM 02487-667) in Introductory Soil Mechanics, New York. BORING LOG GeoSoils, Inc. WO. 4147-A-SC PROJECT: BENNETt BORING B-i SHEET OF1 3112 Lincoln Street DATE EXCAVATED 12-27-03 Sample SAMPLE METHOD: HAND AUGER Standard Penetration Test Groundwater ' CL ' g Undisturbed, Ring Sample w D. U).D 0 E ma Description of Material SM : TOPSOIUCOLLUVIUM @ 0 - 1/21 SILTY FINE SAND, dark brown, moist, loose; porous, - . \__roots: TERRACE DEPOSITS: @ Y2 -4' SILTY FINE SAND, red brown, moist, medium dense 0 to dense. ::• • • .-• Total Depth = 4' No Groundwater Encountered Backfilled 12-27-2003 I I I I I GeoSoils 3ll2 Lincoln Street • , Inc. PLATE BI BORING LOG GeoSoils, Inc. WO. 4147-A-SC PROJECT: BENNE1T BORING SHEET OF 3112 Lincoln Street DATE EXCAVATED 12-27-03 - Sample - SAMPLE METHOD: HAND AUGER Standard Pnetraffon Test Groundwater - 21 0 'Undisturbed, Ring Sample , co 2 . Description of Material SM : TOPSOILICOLLUVILJM @ 0- /' SILTY FINE SAND, dark brown, moist, loose; porous, --\..roots. TERRACE DEPOSITS: : @ M. - 3' SILTY. FINE SAND, red brown, moist, medium dense to dense. • • • Total Depth = 3' - No Groundwater Encountered • Backfilled 12-27-2003 F.. •' ••• 3112 Lincoln Street • • GeoSoHs, Inc. . PLATE B2 I I I I I I I I I I I I I I I I I I BORING LOG GeoSoils, Inc. wo. 4147-A-SC PROJECT: BENNETT BORING B3 SHEET OF 3112 Lincoln Street DATE EXCAVATED 12-27-03 - Sample - SAMPLE METHOD: HAND AUGER Standard Penetration Test Groundwater Undisturbed, Ring Sample - ne CL o M CL 0 E W 75 Description of Material SM : TOPSOIL/COLLUVIUM • ::: @ 0 - W SILTY FINE SAND, dark brown, moist, loose; porous, \ roots. - . TERRACE DEPOSITS: ••: • : © 1/2 - 3' SILTY FINE SAND, red brown, moist, medium dense to dense. Total Depth = 3' No Groundwater Encountered Backfilled 12-27-2003 5- • • GeoSoils Inc. • • 3ll2 Lincoln Street , • PLATE B3 APPENDIX C SEISMICS I I 1 I I I I. I I I I I I I . I I I I I I I- CU a) >- z U) .4-.' a) > w 4- 0 ci) 0 E z 1) > 4-' CU E E :3 0 EARTHQUAKE RECURRENCE CURVE 3112 Lincoln 100 i1 i I .01 .001 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Magnitude (M) W.O. 4147-A-SC Plate C-i 100 1000000 Cl) 100000 10000 1000 RETri7N7pE7- !T317 -VS . rLIr1 - CAMP. & BOZ. (199.7 Rev.) SR 1 0.00 0.25 0.50 0.75 1.00 1.25 1.50 Acceleration (q) 1.50 I I PROBABILITY OF EXCEEDANCE CAMP. &BOZ.(1997Rev)SR1 I . I•I .IAI 25yrs S 50yrs 1.1 .• lvi I- - 100 75 - ____ yrs • uuyrs E S 90- - 70 I . 60-I__ I.. 250-I -. I . 40 CU 30-I 20-I • w10 S _ II JJiI 111•1 JL I. • 0.00 0.25 0.50 0.75 1.00 1.25 • • S S Acceleration (q) I S S • S • W.O. 4147-A-SC S I S Plate C-3 I GENERAL EARTHWORK AND GRADING GUIDELINES General S These guidelines present general procedures and requirements for earthwork and grading as shown on the approved -grading plans, including preparation of areas to filled, placement of fill, installation of subdrains and excavations. The recommendations contained in the geotechnical report arepart of the earthwork and grading guidelines and would supercede the provisions contained hereafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new recommendations which could supersede these guidelines orthe recommendations contained inthe geotechnical report. The contractor is responsible for the satisfactory completion of all earthwork in accordance with provisions of the project plans and specifications. The project soil engineer and engineering geologist (geotechnical consultant) or their representatives should provide observation and testing services, and geOtechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnical Consultant Prior to the commencement of grading, a qualified geotechnical consultant (soilengineer and engineering geologist) should be employed for the purpose of observing earthwork procedures and testing the fills for conformance with the recommendations of the geotechnical report, the approved grading plans, and applicable grading codes and ordinances The gebtechnical consultant should provide testing and observation so that determination may be made that the work is being accomplished as specified. It is the responsibility of the contractor to assist the consultants and keep them apprised of anticipated work schedules and changes, so that they may schedule their personnel accordingly. All clean-outs, prepared ground to receive fihI key excavations, and subdrains should be observed and documented by the project engineering geologist and/or soil engineer prior to placing and fill. It is the contractOrs's responsibility to notify the. engineering geologist and soil engineer when such areas are ready for observation. Laboratory and Field Tests Maximum dry density tests to determine the degree of compaction -should be performed in accordance With American Standard Testing Materials test method ASTM designation D-1 557-78. Random field compaction tests shoUld be performed in accordance with test method ASTM designation. D-1 556-82, D-2937 or D-2922 and D-3017, at intervals of approximately -2 feet of fill height or every 100 cubic yards of fill placed. These criteria would vary depending on the soil conditions and the size of the project. The location and frequency of testing would be at the discretion of the geotechnical consultant. S I U I I I I I I I I] I I I Contractor's Responsibility All clearing, site preparation, and earthwork performed on the project should be conducted by the contractor, with observation by geotechnical consultants and staged approval by the governing agencies, as applicable. It is the contractor's responsibilityto prepare the ground. surface to receive the fill, to the satisfaction of the soil engineer, and to place, spread, moisture condition, mix and compact the fill in accordance with the recommendations of the soil engineer. The contractor should also remove all major non-earth material considered unsatisfactory by the soil engineer. It is the sole responsibility of the contractor to provide adequate equipment and methods. to accomplish the earthwork in accordance with applicable grading guidelines, codes or agency ordinances, and approved grading. plans. Sufficient watering apparatus and compaction equipment should be provided by the contractor with due considerationfor the fill material, rate of placement, and climatic conditions. If, in the opinion of the geotechnical consultant, unsatisfactory conditions such as questionable weather, excessive oversized rock, or deleterious material, insufficient support equipment, etc., are resulting in a quality of work that Is not acceptable, the consultant will inform the contractor, and the contractor is expected to rectify the conditions, and if necessary, stop work until conditions are satisfactory. . . . During construction, the contractor shall properly, grade all surfaces to maintain good drainage and prevent ponding of water. The contractor shall take remedial measures to control surface water and to prevent erosion of graded areas until such time as permanent drainage and erosion control measures have been installed. SITE PREPARATION All major vegetation, including brush, trees, thick grasses, organic debris, and other deleterious material should be removed and disposed of off-site. These removals must be concluded prior to placing fill. Existing fill, soil, alluvium, colluvium, or rock materials determined by the soil engineer or engineering geologist as being unsuitable in-place should be removed prior to fill placement. Depending upon the soil conditions, these materials may be reused as compacted fills. Any materials incorporated as part of the compacted fills should, be approved by the soil engineer. Any underground structures such as cesspools,' cisterns, mining shafts, tunnels, septic tanks, wells, pipelines or other structures not located prior to grading are to be removed or treated in a manner recommended by the soil engineer. Soft, dry, spongy, highly fractured, or otherwise unsuitable ground extending to such a depth that surface processing cannot adequately improve the condition should be overexcavated down to firm ground and approved by the soil engineer before' compaction and filling operations continue. Overexcavated and processed soils which have been properly mixed and moisture Mr. Russell Bennett . Appendix D FiIe:e:\wp9\4100\41 47a.pge . . . . . . . .' . . . Page 2 w_. conditioned should be re-compacted to the minimum relative compaction as specified in these guidelines. Existing ground which is. determined to be satisfactory for support of the fills should be scarified to a minimum depth of 6 inches or as directed by the soil engineer. After the scarified ground is broughtto optimum moisture content or greater and mixed, the materials should be compacted as specified herein. If the scarified zone is grater that 6 inches in depth, it may be necessary to remove the excess and place the material in lifts restricted to about 6 inches in compacted thickness. Existing ground which is not satisfactory to support compacted fill should be overexcavated as required in the geotechnical report or by the on-site soils engineer and/or engineering geologist. Scarification, disc harrowing, or other acceptable form of mixing should continue until the soils are broken down and free of large lumps or clods, until the working surface is reasonably uniform and free from ruts, hoIlow, hummocks, or other uneven features which would inhibit compaction as described previously. Where fills are to be placed on ground With slopes steeperhan 5:1 (horizontal to vertical), the ground should be stepped or benched. The lowest bench, which will act as a key,. should be a minimum of 15 feetwide and should. be at least 2 feet deep into firm material, and approved by the soil engineer and/or engineering geologist. In fill over cut slope conditions, the recommended minimum width of the lowest bench or key is also 15 feet with the key founded on firm material, as designated by the Geotechnical Consultant. As a general rule, unless specifically recommended otherwise by the Soil Engineer, the minimum width of fill keys should be approximately equal to 1/2 the height of the slope.. Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable material. Benching may be used to remove unsuitable materials, although it is understood that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered for unsuitable materials in excess of 4 feet in thickness. All areas to receive fill, including processed areas, removal areas,, and the toe of fill benches should be observed and approved by the soil engineer and/or engineering geologist prior to placement of fill. Fills may then be properly placed and compacted until design grades (elevations). are attained. . . COMPACTED FILLS I . Any earth materials imported or excavated on the property may be utilized in the fill provided that each material has been determined to be suitable bythe soil engineer. These materials should be free of roots, tree branches, other organic matter or other deleterious I 'materials. All unsuitable materials should be removed from the fill as directed by the soil engineer. Soils of poor gradation, undesirable expansion potential, or substandard strength Mr. Russell Bennett ' , Appendix D I , File:e:\wp9\4100\4147a.pge . . . ' .: . '. . '' Page 3 I characteristics may be designated by the consultant as unsuitable and may require blending with other soils to serve as a satisfactory fill material. Fill materials derived from benching operations should be dispersed throughout the fill area and blended with other bedrock derived material. Benching operations should not result I in the benched material being placed only within a single equipment width away from the fill/bedrock contact. I Oversized materials defined as rock or other irreducible materials with a maximum dimension greater than 12 inches should not be buried or placed in fills unless the location of materials, and disposal methods are specifically approved by the soil engineer. Oversized material should be taken off-site or placed in accordance with recommendations of the soil engineer in areas designated as suitable for rock disposal. Oversized material should not be placed within 10 feet vertically of finish grade (elevation) or. within 20 feet I horizontally of slope faces. I .. To facilitate future trenching, rock should not be placed within the range of foundation excavations, future utilities, or underground construction unless specifically approved by the soil engineer and/or the developers representative. If import material is required for grading, representative samples of the materials to be utilized as compacted fill should be analyzed in the laboratory by the soil engineer to determine its physical properties. If any material other than that previously tested is encountered during grading, an appropriate analysis of this material should be conducted by the soil engineer as soon as possible. Approved fill material should be placed in areas prepared to receive fill in near horizontal layers that when compacted should not exceed 6 inches in thickness. The soil engineer may approve thick lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer should be spread evenly and blended to attain uniformity of material and moisture suitable for compaction. Fill layers at a moisture content less than optimum should be watered and mixed, and wet fill layers should be aerated by scarification or should be blended with drier material. Moisture condition, blending, and mixing of the fill layer should continue until the fill materials have a uniform moisture content at or above optimum moisture.. After each layer has been evenly spread, moisture conditioned and mixed, it should be uniformly compacted to a minimum Of 90 percent of maximum density as determined by ASTM test designation, D-1557-78, or as otherwise recommended by the soil engineer. Compaction equipment should be adequately sized and should be specifically designed for soil compaction or of proven reliability to efficiently achieve the specified degree of compaction. • • Mr. Russell Bennett • Appendix D Fi1e:e:\wp9\4100\4147a.pge • • • . Page 4 7w. Where tests indicate that the density of any layer of fill, or portion thereof, is below the required relative, compaction, or improper moisture is in evidence, the particular layer or portion shall be re-worked until the required density and/or moisture content. has been attained. No additional fill shall be placed in an area-until the last placed lift of fill has been tested and found to meet the density and moisture requirements, and is approved by the soil engineer. . Compaction of slopes should be accomplished by over-building a minimum of 3 feet horizontally, and subsequently trimming back to the design slope configuration. Testing shall be performed as the fill is elevated to evaluate compaction as the fill core is being developed. Special efforts may be necessary to attain the specified compaction in the fill slope zone. Final slope shaping should be performed by trimming and removing loose materials with appropriate equipment. A final determination of fill slope compaction should be based on observation and/or testing of the finished slope face. Where compacted fill slopes are, designed steeper than 2:1 (horizontal to vertical), speciflc'material types, a higher minimum relative compaction,.. and special grading procedures, may be recommended'. If an alternative to over-building and cutting back the compacted fill slopes is selected, then special effort should be made to achieve the required compaction in the outer 10 feet of each lift of fill by undertaking the following: An extra piece of equipment consisting of a heavy short shanked sheepsfoot should be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The sheepsfoot roller should also be used to roll perpehdicularto the slopes, and extend out over the slope to provide' adequate compaction to the face of the slope. . Loose fill should not be spilled out over the face of the, slope as each lift is compacted. Any loose fill spilled over a previously completed slope face should be trimmed off or be subject to re rolling. Field compaction tests will be made in the outer (horizontal) 2 to 8 feet of the slope at appropriate vertical intervals, subsequent to compaction operations. After completion of the slope, the slope face should be shaped with a small tractor and then re-rolled with a sheepsfoot to achieve compaction to near the slope face. Subsequent to testing to. verify. compaction, the slopes should be grid-r011ed to achieve compaction to the slope face. Final testing should be used to confirm compaction after grid rolling.' . 'Where testing indicates less than adequate compaction, the contractor will be responsible to ,rip, water, mix and re-compact the slope material, as necessary to achieve compaction. Additional testing should be performed to verify compaction. Mr. Russell Bennett ' . ' , . . . Appendix D File:e:\wp9\4100\41 47a.pge . . . . . ' ' Page 5 U . ,. 6. Erosion control and drainage devices should be designed by the project civil engineer in compliance with ordinances of the controlling governmental agencies, and/or in accordance with the recommendation of the soil engineer or engineering geologist. . . . . . . . . SUBDRAIN INSTALLATION U .Subdrains should be installed in approved ground in accordance with the approximate : alignment and details indicated by the geotechnical consultant. Subdrain locations or materials should not be changed or modified without approval of the geotechnical U consultant. The soil engineer and/or engineering geologist may recommend and direct changes in subdrain line, grade and drain material in the field, pending exposed conditions. The location of constructed subdrains should be recorded by the project civil engineer. .I . . . . EXCAVATIONS Excavations .and cut slopes should be examined during grading by the engineering I geologist. If directed by the engineering geologist, further excavations or overexcavation and re-filling of cut areas should be performed and/or remedial grading of cut slopes should be performed. When fill over cut slopes are to be graded, unless otherwise approved, the U cut portion of the slope should be observed by the engineering geologist prior to placement of materials for construction of the fill portion of the slope. U . ' The engineering geologist should observe all cut slopes and should .be notified by the contractor when cut slopes are started. If, during the course of grading, unforeseen adverse. or potential adverse geologic conditions are encountered, the engineering geologist and U . . soil . engineer should investigate,, evaluate and make recommendations to treat. these problems. The need for cut slope buttressing or stabilizing should be based on in-grading I evaluation by the engineering geologist, whether anticipated or not.. Unless otherwise specified in soil and geological reports, no cut slopes should be excavated higher or steeper than that allowed by the ordinances of controlling U governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractors responsibility. U . . Erosion control and drainage devices should be designed bythe project civil engineer and should be constructed in compliance with the ordinances of the controlling governmental U agencies, and/or in accordance with the recommendations of the soil engineer or engineering geologist. . . .. .. . Mr. Russell Bennett ' . . . . Appendix D I . FiIe:e:\wp9\4100\4147a.pgé . .,. Page 6 s-. '. .. .. ' . .. COMPLETION U Observation, testing and consultation bythegeotechnical consultant should be conducted during the grading operations in order to state an opinion that all cut and filled areas are I graded in accordance with the approved project specifications. After completion of grading and after the soil engineer and engineering geologist have I finished their observations of the work, final reports should be submitted subject to review by the controlling governmental agencies. No further excavation or filling should be I undertaken without prior notification of the soil engineer and/or engineering geologist. All finished cut and fill slopes should be protected from erosion and/or be planted in accordance with the project specifications and/or as recommended by a landscape I architect. Such protection and/or planning should be undertakenas soon as practical after completion of grading. JOB SAFETY General . I . At GeoSoils, Inc. (GSI) getting the job done safely is of primary concern. The following is the company's safety considerations for use by all employees on multi-employer construction sites. On ground personnel are at highest risk of injury and possible fatality I on grading and construction projects. GSI recognizes that construction activities will vary on each site and that site safety is the prime responsibility of the contractor; however, everyone must be safety conscious and responsible-at all times. To achieve our goal of I avoiding accidents, cooperation between the client, the. contractor and GSI personnel must be maintained. . . I . In an effort to minimize risks associated with geotechnical testing and observation, the following precautions are to be implemented forthe safety of field personnel on grading and. I construction projects: Safety Meetings: GSI field personnel are directed to attend contractors regularly I .scheduled and documented safety meetings. Safety Vests: Safety vests are provided for and are to be worn by GSI personnel at I . . . all times when they are working in the field. Safety Flags:. Two safety flags are provided to GSI field technicians; one is to be I affixed to the vehicle when on site, the other is to be placed atop the spoil pile on all test pits. . . I Mr. Russell Bennett . . . • . . . Appendix D I . FiIe:e:\wp9\4100\4147a.pge . . . .. •. . Page 7 CoARARe- Ind!_ . . ., . . Flashing Lights: All vehicles stationary in the grading area shall Use rotating or flashing amber beacon, or strobe lights, on the vehicle during all field testing. While operating a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. S In the event that the contractor's representative observes any of our personnel not following the above, we request that it be brought to the attention of our office. Test Pits Location. Orientation and Clearance I The technician is responsible for selecting test pit locations. A primary concern should be the technicians's safety. Efforts will be made to coordinate locations with the grading contractors authorized representative, and to select locations following or behind the I :established traffic pattern, preferably Outside of current traffic. The contractors authorized representative (dump man, operator, supervisor, grade: checker, etc.) 'should direct excavation of the pit and safetyduringthetestperiod. Of paramount concern should be the soil technicians safety and.obtaining enough tests to represent the fill. Test pits should be excavated so that the spoil pile is placed, away form oncoming traffic, I . whenever possible. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates the fill be maintained ma driveable condition. Alternatively, the contractor may wish to park a piece of equipment in front of the test holes, particularly in small fill areas or those with limited access. ' I , ' A zone of non-encroachment should be established for all test pits. No grading equipment should enterthis zone during the testing procedure. The zone should extehd'approximately 50 feet outward from the center of the test pit.. This zone is established for safety and to I avoid excessive ground vibration which typically decreased test results When taking slope tests the technician should park.the vehicle directly above or below the I , test location. If this is not. possible, a prominent flag' should be placed at the top of the slope. The contractor's representative should effectively keep. all equipment at a safe I 'operation distance (e.g., 50 feet) away from the slope during this 'testing. The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter of the fill in a I , highly visible location, well away from the equipment traffic pattern. The contractor should inform our personnel of all changes to haul roads; cut and fill areas or other factors that may I , affect site access and site safety. In the event that the technicians safety is jeopardized or compromised as a result of the, I '" ' contractors failure to comply with any of the above, the technician.is required, by company' policy, to immediately withdraw and notify his/her supervisor. , The grading contractors Mr., Russell Bennett. ' . .. . . . Appendix D File:e:\wp9\4100\4147a.pge .. , . , . . . . ' '' Page 8 I representative will eventually be contacted in an effort to effect a solution. However, in the interim, no further testing will be performed until the situation is rectified. Any fill place can be considered unacceptable and subject to reprocessing, recompaction or removal. ln.the event that the soil technician does not comply with the above.Or other established safety guidelines, we request that the contractor brings this to his/her attention and notify this office. Effective communication and coordination between the contractors representative and the soils technician is strongly encouraged in order to implement the above safety plan. Trench and Vertical Excavation It is the contractor's responsibility to provide safe access into trenches where compaction testing is needed. . U Our personnel are directed not to enter any excavation or vertical cut which: 1) is 5 feet or deeper unless shored or laid back; 2) displays any evidence of instability, has any loose I rock or other debris which could fall into the trench; or 3) displays any other evidence of any unsafe conditions regardless of depth. All trench excavations or vertical cuts in excess of 5 feet deep, which any person enters, should be shored or laid back. Trench access should be provided in accordance with CAL- OSHA and/or state and local standards. Our personnel are directed not to enter any trench by being lowered or "riding down" on the eqUipment. I If the contractor fails to provide safe access to trenches for compaction testing, our company policy requires that the soil technician, withdraw and notify his/her supervisor. The contractors representative will eventually be contacted, in an effort to effect a solution. All I. backfill not tested due to safety concerns or other reasons could be subject to reprocessing and/or removal. • . If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the contractor and owner/developer on notice to immediately correct the'situation. If corrective steps are not taken, GSl then has an obligation to notify CAL-OSHA and/or the proper authorities. I . • Mr. Russell Bennett • • • • • • Appendix D .I File:e:\wp9\4100\4147a.pge : • • ' Page 9 Giensails. Inc. •• • • • • , I I TEST FIT SAFETY . DIAGRAM I SIDE VIEW SPOIL FILE 10 ~~"o ( NOT TO SCALE) TOPVIEW. 100 FEET I- LL 50 FEET in 50 FEE' 1. I SPOIL •4TEST PIT.. ' vecLE PILE I _ I FLAG APPROXIMATE ENTER OF TEST PIT NOT TO SCALE.) PLATE EG-16 I I Geotechnical ° Geologic. Coastal. Environmental I 5741 Palmer Way • Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915 www.geosoilsino.com I September 27, 2010. I W.O. 4147-Al-SC Mr. Russell Bennett I P.O. Box 356 . I Solana Beach, California 92075 I Subject: Geotechnical Update for Structural Design, 3.112 Lincoln Street, San Diego County, California I Dear Mr. Bennett: I In accordance with your request and authorization, GeoSoils, Inc. (GSI) has performed an update of our preliminary geotechnical investigation (GSI, 2004b, seethe Appendix) forthe proposed development at the subject site. The purpose of this study was to update the I geotechnical recommendations related to project structural design for conformance with the 2007 California Building Code ([2007 CBC], California Building Standards Commission [CBSC], 2007). The scope of services GSI provided for this geotechnical update included: I 1) a brief site reconnaissance; 2)'a review of previous geotechnical reports prepared for the site GSI (2007, 2004a, and 2004b); and 3) the preparation of this geotechnical. update letter. Unless specifically superceded herein, the conclusions and recommendations I contained in the GSI (2007,2004a, and 2004b) remain valid and applicable and should be appropriately implemented during project design and construction. PROPOSED DEVELOPMENT. It is our understanding that proposed development consists of preparing the site for the construction of three, 3-story mixed-used structures. GSI anticipates that the buildings.will I . incorporate wood, steel, and/or concrete masonry construction with concrete slab-on grade-floors. Building loads are assumed typical for this type of commercial/residential development. SITE RECONNAISSANCE GSI performed a site reconnaissance on September 23, 2010: Site conditions were generally similar to those observed during field work in preparation of GSI (2004b) with the I exception of a recently constructed residential development immediately east of the subject site. . . . . I I UPDATE SEISMIC SHAKING PARAMETERS I Based on the site conditions, the table below summarizes the site-specific seismic design criteria obtained from the 2007 CBC. (CBSC, 2007), and the 2006 International Building Code (IBC), Chapter 16 Structural Design, Section 1613. We used the computer. program I Seismic Hazard Curves and Uniform Hazard Response Spectra, provided by the United States Geological Survey ([USGS], 2009). The short-spectral response uses a period of 0.2 seconds. IH N. ______________ - - ,- u(( . •--.- j --- ' UE - JB.6fREFERENCE. Site Class D Table 1613.5.2 Spectral Response - (0.2 sec), S 1.33g Figure 1613.5(3) Spectral Response - (1 sec), S 0.50g Figure 1613.5(4) Site Coefficient, Fa 1.0 Table 1613.5.3(1) Site Coefficient, F 1.5 Table 1613.5.3(2) Maximum Considered Earthquake Spectral 1.33g Section 1613.5.3 Response Acceleration (0.2 sec), SMS (Eqn 16-37) Maximum Considered Earthquake Spectral 0.75g Section 1613.5.3 Response Acceleration (1 sec), SM1 (Eqn 16-38) 5% Damped Design Spectra! Response 0 g Section 1613.5.4 Acceleration (0.2 sec), S0 (Eqn 16-39) 5% Damped Design Spectral Response 0 50 g Section 1613.5.4 Acceleration (1 sec), SDI (Eqn 16-40) Distance to Seismic Source (Newport - Inglewood [offshore]) 5.0 1 k . (8 . m) from Blake (2000a) . Upper Bound Earthquake (Newport - Inglewood [offshore]) Mw 6.9* Probabilistic Horizontal Site Acceleration ([PHSAJ 10% probability 034 g of exceedance in 50 years) from Blake (2000c) 1* International Conference of Building Officials (ICBO, 1998) Conformance to the above criteria for seismic design does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur in the event'of a large earthquake. The primary goal of seismic design is to protect life, not to eliminate all damage, since such design may be economically prohibitive. In order to reduce the effects of cumulative seismic damage, GSI recommends a visual inspection by qualified geotechnical and structural engineers following significant local seismic events (M>4.5), should any indications of distress or cracking be apparent. Mr. Russell Bennett W.O. 4147-Al-SC 3112 Uncoln Street, Carlsbad T September 27, 2010 File: e:\wp9\4900\4972a1 .UOP Page 2 GeeSeifis, Inc. UPDATE PRELIMINARY RECOMMENDATIONS -FOUNDATIONS Preliminary Foundation Diqn In the event our understanding of the proposed development is not correct or any changes in the design, location, or loading conditions of the proposed structures are made, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. The information and recommendations presented in this section are considered minimums and are not meant to supercede design(s) by the project structural engineer or civil engineer specializing in structural design. Upon request, GSl could provide additional consultation regarding soil parameters, as related to foundation design. They are considered preliminary recommendations for proposed construction, in consideration of our field investigation, and laboratory testing and engineering analysis. Our review, field work, and previous laboratory testing (GSI, 2004a and 2004b) indicates that onsite soils have a very low expansion potential (E.l. 0 to 20) with a plasticity index (P1) less than 15. Preliminary recommendations for foundation design and construction are presented below. Final foundation recommendations should be provided at the conclusion of grading based on laboratory testing of fill materials exposed near finish grade. All foundations should be designed in accordance with the 2007 CBC. Design An allowable soil bearing pressure of 1,500 psf may-be used for the design of continuous footings with a minimum width of 12 inches and minimum depth of 12 inches, and for the design of isolated pad footings 24 inches square and 24 inches deep founded entirely into engineered fill or competent formational material (terrace deposits). The bearing value may be increased by 20 percent for each additional 12 inches in depth to a maximum value of 2,500 psf. Foundations for a given structure should not be simultaneously supported by engineered fill and formational materials. Otherwise differential settlement and distress may occur. Isolated pad and column footing should be connected to the main foundation by grade beam or tie beam in at least one direction to prevent lateral drift. An allowable coefficient of friction between concrete and engineered fill or bedrock of 0.35 may be used with the dead load forces. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third.. Mr. Russell Bennett • W.O. 4147-Al-SC 3112 Lincoln Street, Carlsbad • September 27, 2010 Fi1e:e:\wp9\4900\4972a1 .uop Page 3 Geosoils, Inc. I 4. Passive earth pressure may be computed as an equivalent fluid having a density of 250 pounds per cubic foot (pcl) with a maximum earth pressure of 2,500 psf. I 5. All footings should maintain a minimum 7-foot horizontal distance between the base of the footing and any, adjacent descending slope, and minimally comply with the I .guidelines depicted on Figure 1805.3.1 of the 2007 CBC (CBSC, 2007). I . FoUndation Settlement Provided the recommendations in GSI (2004a and 2007) and herein are properly followed, foundations systems may be designed to accommodate a worst-case differential I settlement of 1 inch in a 40-foot horizontal span (angular distortion = 1/480). I . Footing Setbacks . . All footings should maintain a minimum 7-foot horizontal setback from the base of the I .footing to any descending slope. This distance is measured from the footing face at the bearing elevation. Footings should maintain a minimum horizontal setback . of H/3 (H =slope height) from the base of the footing to the descending slope face and no less I , than 7 feet nor need to be greater than 40 feet. Footings adjacent to unlined drainage swales should be deepened to a minimum of.6,inches below the invert of the adjacent unlined swale. Footings for structures superjacent to retaining walls should be deepened I . ' so as to extend below a 1:1 projection from the heel of the wall. Alternatively, walls may be designed to accommodate surcharge loads from buildings or appurtenances as evaluated by 'the project structural engineer. Planned retaining walls and building I .foundations near the eastern property line may need to be deepened below al :1 projection up from wall footings on the easterly, adjacent property. This will require further I evaluation during the grading plan review stage. Construction I ' The following foundation construction recommendations are presented as a minimum criteria from a soils engineering standpoint. The onsite soils expansion potentials are generally Very low (E.l. 0 to 20) with a P1 less than 15. Recommendations for very low expansive soil conditions are presented herein. ' I Recommendations by the project structural engineer or architect, which may exceed the soils engineer's recommendations, should take precedence over the following minimum requirements. Final foundation design will be provided based on the expansion potential I of the near-finish grade soils at the conclusion of grading. 'I I ' . Mr. Russell Bennett . , W.O. 4147-Al-SC 3112 Lincoln Street, Carlsbad . September 27, .2010 FiIe:e:\wp9\4900\4972a1 uop . ' ' . . . Page 4 GeeSefls' Inc. I I Very Low Expansion Potential (E.l. 0 to 20) with a P1 Less Than 15' I 1. Exterior and interior footings should be founded into engineered fill or formational materials at a minimum depth of 12 inches for one-story floor loads, 18 inches for two-story floor loads, and 24 inches for three-story floor loads, below the lowest I adjacent ground surface. Isolated column and panel pads, or wall footings should be 24 inches square and founded at a minimum depth of 24 inches. All footings should be reinforced with two No. 4 reinforcing bars, one placed near the top and I one placed near the bottom of the footing. Continuous footing widths should be a minimum of12 inches for one-story loads, 15 inches for two-story loads, and I ' 18 inches for three-story loads. A grade beam, reinforced as above, and at least 12 inches wide should be provided- across large (e.g., doorways) entrances. The base of the grade beam should be at I . the same elevation as the bottom'of adjoining footings. Isolated, exterior square footings should be tied within the main foundation in at least one direction with a grade beam. ' Slab-on-grade floors (including garages)should be a minimum of 5 inches thick, I .and should be reinforced with No.3 reinforcing bars at 18 inches on center in both directions. All .slab reinforcement'shôuld be supported to ensure placement near the vertical midpoint of the concrete. "Hooking" of reinforcement is not considered I . an acceptable method of positioning the reinforcement. The structural engineer should evaluate slab thickness and reinforcement based on anticipated loading and I use. ' Garage slabs should be poured separately from the structural footings and quartered with expansion joints or saw cuts. A positive separation from the footings . I ' should be maintained with expansion joint material to permit relative movement. Presaturation 'is not required for these soil conditions. The moisture content of the I ' ' subgrade soils, however, should be equal to or greater than optimum moisture. content in the slab areas prior to the placement of the vapor retarder. SOIL MOISTURE CONSIDERATIONS I GSI has evaluated the potential for vapor or water transmission through interior concrete slabs-on-grade, in light of typical residential floor coverings and improvements. Please I note that slab moisture emission' rates, range from about 2 to 27 lbs/24 hours/1,000 square" feet from a typical slab (Kanare, 2005), .while floor covering manufacturers generally recommend about 3 lbs/24 hours as an upper limit. Thus, the client will need to evaluate I ' the following on a cost v. benefit basis, along with disclosure to all interested/affected parties. I Mr. Russell Bennett . ' , W.O. 4147-Al-SC 3112 Lincoln Street, Carlsbad ' ' ' ' ' ' ' September 27, 2010 Fi!e:e:\wp9\4900\4972a1uop ' ' ' ' ' Page 5 ' . ' '. . GoSouL, Inc. ' Considering the anticipated typical water vapor transmission rates, floor coverings and improvements (to be chosen by the client) that can tolerate those rates without distress, the following alternatives are provided: Concrete slabs should be a minimum of 5 inches thick. Concrete slab underlayment should consist of a 1 0mil to 15-mil vapor retarder, or equivalent, with all laps and penetrations (i.e., pipe, ducting, rebar, etc.) sealed per the 2007 CBC (CBSC, 2007) and the manufacturer's recommendation. The vapor retarder should comply with the ASTM E 1745 - Class A or B criteria, and be installed in accordance with ACI 302.1R-04 and ASTM E 1643. Slab underlayment should consist of 2 inches of washed sand (SE >30) placed above the vapor retarder. The vapor retarder shall be underlain by 2 inches of washed sand (SE>.30) placed directly on properly prepared subgrade soils, and should be sealed to provide a continuous water-resistant barrier underthe entire slab, as discussed above. All slabs should be additionally sealed with suitable slab sealant. Concrete should have a maximum water/cement ratio of 0.50. This does not supercede the 2007 CBC (CBSC, 2007) for corrosion or other corrosive requirements. Additional -concrete mix design recommendations should be provided by the structural consultant and/or waterproofing specialist. Concrete finishing and workablity should be addressed by the structural consultant. and a waterproofing specialist. . Where slab water/cement ratios are as indicated above, and/or admixtures used, the structural consultant should also make changes to the concrete in the grade beams and footings in kind, so that the concrete used in the foundation and slabs are designed and/or treated for more uniform moisture protection. . Owners(s) and all interested/affected • parties should be specifically advised which areas are suitable for tile flooring, wood flooring, or other types of. water/vapor-sensitive flooring and which are not suitable. In all planned floor areas, flooring shall be installed per the manufactures recommendations. Additional recommendations regarding water or vapor transmission should be provided by the architect/structural engineer/slab or foundation designer and should be consistent with the specified floor coverings indicated by the architect. Regardless of the mitigation, some limited moisture/moisture vapor transmission through the slab should be anticipated. Construction crews may require special training for installation of certain product(s), as well as concrete finishing techniques. The use of specialized product(s) 'should be approved by the slab designer and water-proofing Mr. Russell Bennett W.O. 4147-Al-SC 31,12 Lincoln Street, Carlsbad September 27, 2010 File:e:\wp9\4900\4972a1 .uop Page 6 GeeSells, Inc. I I consultant. Atechnical representative of the flooring contractor should review the slab and moisture retarder plans and provide comment prior, to the construction of the residential I foundations or improvements. The vapor retarder contractor should have representatives onsite during the initial installation. I WALL DESIGN PARAMETERS Conventional Retaining Walls The design parameters provided below assume that either non expansive soils (typically I Class 2 permeable filter material or Class 3 aggregate base) or native onsite materials (up to and including an E.I. of 50) are used to backfill any retaining walls. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the I plans. Below grade walls should be waterproofed. The foundation system for the proposed retaining walls should be designed in accordance with the recommendations I .presented in this and preceding sections of this report, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade into engineered fill or formational materials (excluding landscape layer, 6 inches) and should be 24 inches in I .width. There should be no increase in bearing for footing. width. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site-specific conditions. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid pressure (EFP) of 65 pcf, plus any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 10 feet high. Design parameters for walls less than 3 feet in height may be superceded by City and/or County standard design. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions due to traffic, structures, seismic events, or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. Mr. Russell Bennett W.O. 4147-Al-SC 3112 Lincoln Street, Carlsbad September 27, 2010 File:e:\wp9\4900\4972a1.uop Page 7 GSufl, Inc.. I I Seismic Surcharge for Retaining Walls I .For retaining walls that are over 6 feet in height, or within 6 feet or less of a building, that may impede ingress/egress, GSI recommends that the walls be evaluated for a seismic surcharge (Section 1630A.1.1.5 of the 2007 CBC [CBSC, 2007]). The site walls in this I category should maintain an overturing Factor-of Safety (FOS) of about 1.2, when the seismic surcharge is applied. The seismic surcharge should be applied as a uniform load from the bottom of the footing (excluding shear keys), to the top of the backfill at the heel I of the wall footing for restrained walls and an inverted triangular distribution for cantilever walls. This seismic surcharge pressure may be taken as 1OH, where "H" is the dimension taken as the height of the retained material for the top of backfill. The resultant force I should be applied at a distance 0.6H up from the bottom of the footing. For the evaluation of the seismic surcharge, the bearing pressure may exceed the static value by one-third, considering the transient nature of this surcharge. In addition to the above comments, GSI I recommends that our field representative observe the temporary backcuts and footing excavations for the walls. Temporary cuts for all wall installations should not exceed I 1½:1 (h:v) inclinations, and should not be open for more than 90 days per cut, from start to finish. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. RETAIND MTERIAL FLOID,WEIGHT CT ION -EWJDWElGHT PC F4' '-t O1lZONTAl VERTICAL)i$ . NAT VEBACKFlLL**) Level* . 35 . 45 2tol 50 60 * Level backfill behind a retaining wall is defined as compacted earth materials, properly drained, without a slope for a distance of 2H behind the wall ** As evaluated by testing, P.1. <15, E.I. <21, S.E. >30, and <10% passing No. 200 sieve. *** As evaluated by testing, E.L.- <50, S.E. >25 and <15% passing No. 200 sieve. Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1, 2, and 3, present the back drainage options discussed below. Backdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or 3/4-inch to 11/2-inch gravel wrapped in approved filter fabric (Mirafl 140 or equivalent). . For low expansive backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the walls and upward at least 1 foot. For native backfill that has an E.I. up to 50, continuous Class I . 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance I . Mr. Russell Bennett . . . W.O. 4147-Al-SC 3112 Lincoln Street, Carlsbad . . September 27, 2010 Fi1e:e:\wp9\4900\4972a1 .uop . . . Page 8 I. . . . : . .GeoSollsl, Inc. . . .. . Structural footing or settlement-sensitive improvement - Provide surface drainage via an (1) Waterproofing / engineered V-ditch (see civil plans membrane / for details) CMU or / 2:1 NO slope reinforced-concrete wall eor1eve1 ±12 inches - 12 ihes (2) Gravel Proposed grade I :. \ sloped to drain :.: \ per precise civil bH Native backfill ..: ,' \ drawings / \\\ \ (5) Weep hole AA e 1:1 NO or flatter A\\ \\ \ .. backcut to be Footing and wall - properly benched design by others_-[ (6) Footing Waterproofing membrane. Gravel: Clean, crushed, 3/4 to 1Y2 inch. Filter fabric: Mirafi 140N or approved equivalent. Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient sloped to suitable, approved outlet point (perforations down). Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineer to. provide drainage at toe of wall. No weep holes for below-grade walls. Footing: If bench is created behind the footing greater than the footing Width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by geotechnical consultant. . . . . . J RETAINING WALL DETAIL — ALTERNATIVE. A Detail 1 ] Structural footing or (1) Waterproofing settlement-sensitive improvement - membrane (optional) I Provide surface drainage via engineered V-ditch (see civil plan details) CMU or 24 NO slope' reinforced-concrete all / 6inches .• . : . .•. ,'- (2) Composite .. ............... ..... ... . drain ..... \\ (5) Weep hole_\ V. ,,- Proposed grade '- (3) Filter fabfl Native backfill / sloped to drain / per precise civil ., drawings J.- :.... :.: -.: (4)PitD . .. .. >.-\\ 1:1 NO or flatter ___ _____ _____ \55 backcut to be -. properly benched Footing and wall i . . design by others - .•• (6) 1 cubic foot of. . 3/4-inch crushed rock (7) Footing (1) Waterproofing membrane (optional): Liquid boot or approved mastic equivalent. a •u Drain: Miradrain 6000 or J-drain 200 or equivalent for non-waterproofed walls; Miradrain 6200 or J-drain 200 or equivalent for waterproofed walls (all perforations down). Filter fabric Mirafi 140N or approved equivalent; place fabric flap behind core. Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient to proper outlet point (perforations down): Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineerto provide drainage at toe of wall. No weep holes for below-grade walls. Gravel: Clean, crushed, 3/4 to 1Y2 inch. Footing: If bench is created behind the footing greater than the footing width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by geótechnical consultant. • . . • G AWJ RETAINING WALL DETAIL - ALTERNATIVE B Detail 2 I (1) Waterproofing membrane - CMUor reinforced-concrete wall __-4- ±12 inches 1' (5) Weep hole—. H j—Proposed grade / sloped to drain per precise civil drawings Footing and wall Structural footing or settlement-sensitive improvement Provide surface drainage 21 NO slope C. or eve[. : •. \\ : (8) Native backfill (6) Clean sand backfill 11 NO or flatter : - backcut to be (3) Filter fabric properly benched (2) Gravel I I I I. I I I I I I Heel I LJY L)LI rwidt N — (4) Pipe Footing (1) Waterproofing membrane: Liquid boot or approved masticequivalent. Gravel: Clean, crushed, 3/4 to 1Y2 inch. Filter fabric: Miraf I 140N or approved equivalent. Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient to proper outlet point (perforations down). Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. Clean sand backfill: Must have sand equivalent value (S.E.) of 35 or greater; can be densified by water jetting upon approval by geotechnical engineer. Footing: If bench is created behind the footing greater than the footing width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by geotechnical consultant. Native backfill: If E.L (21 and S.E. )35 then all sand requirements also may not be required and will be reviewed by the geotechnical consultant GeJiJ RETAINING WALL DETAIL - ALTERNATIVE C Detail 3 LI I I I I IH I I with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited 0 access and confined areas, (panel) drainage behind the wall may be constructed in I accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an E.I. greater than 50 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should I conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than I ±100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes, only, in walls higher than 2 feet, is not recommended. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with native soil (E.l. <50). Proper I surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the back of all retaining structures. The. I .use of a waterstop should be considered for all concrete and masonry joints. Wall/Retaining Wall Footing Transitions I Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from formation to fill, the I . civil designer may specify either: A minimum of a 2-foot overexcavation and re-compaction of cut materials for a I distance of 2H, from the point of transition. Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints I .or crack control joints) such that a angular distortion of 1/360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be placed no greater than 20 feet on-center, in accordance with the structural I engineer's/wall designer's recommendations, regardless of whether or nottransition conditions exist. Expansion joints should be sealed with afiexible, non-shrink grout. I c) Embed the footings entirely into formational materials (i.e., deepened footings). I If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS Some of the soil materials on site may be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential I I I I Mr. Russell Bennett 3112 Lincoln Street, Carlsbad FiIe:e:\wp9\49004972a1 .uop Inc. W.O. 4147-Al-SC September 27, 2010 Page 12 MW for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended that disclosure be provided to all interested/affected parties of this long- term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: I 1. The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points above (or 125 percent of) the soils' optimum moisture content to a depth of 18 inches below subgrade elevation. If very low expansive soils are present, only optimum moisture content, or greater, is required and, specific presoaking is not warranted. The moisture content of the subgrade should be proof tested within 72 hours prior to pouring concrete. Concrete slabs should be cast over a non-yielding surface, consisting of a 4-inch I . layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. If very low expansive soils are present, the rock or gravel I . or sand may be deleted. The layer or subgrade should be wet-down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and approaches shoUld additionally have a thickened edge (12 inches) adjacent to all. landscape areas, to help impede infiltration of landscape water under the slab. The use of transverse and longitudinal control joints are recommended to help I control slab cracking due to concrete shrinkage or expansion. Two Ways to mitigate such cracking are: a) add. a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of I ' , control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. . . In order to reduce the potential for unsightly cracks, slabs should be'reinforced at mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each I . direction. If subgrade soils within the top 7 feet from finish grade are very low expansive soils (i.e:, E.I. :g20), then 6x6-W1 .4xW1 .4 welded-wire mesh may be substituted for the rebar, provided the reinforcement is placed on chairs, at slab I .mid-height. The exterior slabs should be scored or saw cut, ½ to % inches deep, often enough so that no section is greater than 10 feet by 10 feet. For sidewalks or narrow slabs, control joints should be provided at intervals of every 6 feet. The I , slabs should be separated from the foundations and sidewalks with expansion joint filler material. •. , I ' ' Mr. Russell Bennett W.O. 4147-Al-SC 3112 Lincoln Street, Carlsbad September 27, 2010 File:e:\wp9\4900\4972a1'.uop: . . . , Page 13 I , I No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression I . strength should be a minimum of 2,500 psi. Driveways, sidewalks, and patio slabs adjacent to the house should be separated I from the house with thick expansion joint filler material. In areas directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. I . Planters and walls should not be tied to the house.. I . 8. Overhang. structures should be supported on the slabs; or structurally 'designed with continuous footings tied in at least two directions. If very low expansion soils are present, footings need only be tied in one direction. I Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These I segments should be keyed or doweled together. I . Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to differential accommodate settlement and expansive soil conditions. I 11. , Positive site drainage should be maintained at all times. Finish grade on the lots should provide a minimum of 1 to 2 percent fall to the street, as indicated herein. It should be kept in mind that drainage reversals could occur, including I . post-construction settlement, if relatively flat yard drainage gradients are not periodically maintained by the homeowner. I ' 12. ' Air conditioning (NC) units should be supported by slabs that are incorporated into. the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. NC waste water lines should be drained to a suitable I 'non-erosive outlet. 13. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed. Finishing and curing practices should be performed per the — ' Portland Cement Association Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of I soils, and fertilizers used on site. I UTILITIES I Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. Due Ii Mr. Russell Bennett . ' W.O. 4147-Al-SC 3112, Lincoln Street, Carlsbad September 27, 2010 File:e:wp9\4900\4972a1.uop ' ' . ' ' ' ' ' ' Page 14 I. I I I I I .1 I I I . I to the potential for differential settlement, air conditioning (NC) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. NC waste waterlines should be drained to a suitable outlet. OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. This report presents minimum design criteria for the design of slabs, foundations and other elements possibly applicable to the project. These criteria should not be considered as substitutes for actual designs by the structural engineer/designer. Please note that the recommendations contained herein are not intended to preclude the transmission of water or vapor through the slab or foundation. The structural engineer/foundation and/or slab designer should provide recommendations to not allow water or vapor to enter into the structure so as to cause damage to another building component, or so as to limit the installation of the type of flooring materials typically used for the particular application. The structural engineer/designer should analyze actual soil-structure interaction and consider, as needed, bearing, expansive soil influence, and strength, stiffness and defiections in the various slab, foundation, and other elements in order to develop appropriate, design-specific details. As conditions dictate, it is possible that other influences will also have to be considered. The structural engineer/designer should consider all applicable codes and authoritative sources where needed. If analyses by the structural engineer/designer result in less critical details than are provided herein as minimums, the minimums presented herein should be adopted. It is considered likely that some, more restrictive details will be required. If the structural engineer/designer has any questions or requires further assistance, they should not hesitate to call or otherwise transmit their requests to GSI. In order to mitigate potential distress, the foundation and/or improvement's designer should confirm to GSl and the governing agency, in writing, that the proposed foundations and/or improvements can tolerate the amount of differential settlement and/or expansion characteristics and other design criteria specified herein.. PLAN REVIEW Final project plans (grading, precise grading, foundation, retaining wall, landscaping, etc.), should be reviewed by this office prior to construction, so that construction Js in accordance with the conclusions and recommendations of this report. Based on our I I I I I I Mr. Russell Bennett 3112 Lincoln Street, Carlsbad File:e:\wp9\4900\4972a1.uop W.O. 4147-Al-SC September 27, 2010 Page 15 review, supplemental recommendations and/or further geotechnical studies may be warranted. The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and, natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty, either express or implied, is given: 'Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use, of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review' by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. ' Mr. Russell Bennett , W.O. 4147-Al-SC 3112 Lincoln Street, Carlsbad ' ' ' ' ' September 27, 2010 FiIe:e:\wp9\4900\4972a1 .uop ' ' ' ' ' Page 16 I The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to contact our office. Respectfully H 4P David W. Skelly .I Ryan oehmer Project Geologist I P Attachment: Appendix - Referenes Distribution: (1) Addressee (via email) (4) Karnak Planning & Design, Attn: Mr. Robert Richardson (2 wet signed) (1) Concorde Consulting Group, Inc., Attn: Mr. Koladi M. Kripanarayanan via email) (1) Conway and Associates, Attention: Mr. Mike Pasko (via email) Mr. Russell Bennett W.O. 4147-Al -Sc 3112 Lincoln Street, Carlsbad September 27, 2010 Fi!e:e:\wp9\4900\4972a1 .uop • Page 17 -Geosdils, Inc. I I . APPENDIX . REFERENCES I .. ACI Committee 318,2008, Building code requirements for structural concrete (AC131 8-08) and commentary, dated January ACI Committee 302,2004, Guide for concrete floor and slab construction, ACI 302.1 R-04, I . dated June. American Society for Testing and Materials, 1998, Standard practice for installation of water vapor retarder used in contact with earth or granular fill under concrete slabs, Designation: E 1643-98 (Reapproved 2005). . . I , 1997, Standard specification for plastic water vapor retarders used in contact with soil or granular fill under concrete slabs, Designation: E 1745-97 (Reapproved 2004). I California Building Standards Commission, 2007, California Building Code. I . GeoSoils, Inc., 2007, Geotechnical review of rough grading plans (first submittal), Uncoln and Oak Project, 3112 Lincoln Street, Carlsbad, San Diego County, California, W.O. 4147-A-SC, dated May 4. .' . 2004a, Soil corrosivity results, 3112 Lincoln Street, Carlsbad, San Diego County, I. . California, W.O. 4147-A-SC, dated January 22. 2004b, Preliminary geotechnical evaluation, 3112 Lincoln Street, Carlsbad, I . . San Diego County, California, W.O. 4147-A-SC, dated January 14. International Code Council, Inc., 2006, International building code and international I . residential code, Country Club Hills, Illinois, IRC and IBC. International Conference of Building Officials, 1998, Maps of known active fault near- source zones in California and adjacent portions of Nevada. Kanare, Howard, M., 2005, Concrete floors and moisture, Engineering Bulletin 119, Portland Cement Association. Romanoff, M., 1989, Underground corrosion, National Bureau of Standards Circular 579, I . Published by National. Association of Corrosion Engineers, Houston, Texas, originally issued April 1, 1957. . I State of California, 2009, Civil Code, Sections 895 et seq. . . . . United States Geological Survey, 2009, Seismic hazard curves and uniform hazard I . response spectra - v5.0.9, dated October 21. . I Gils, I I Geotechnical Geologic. Coastal Environmental I 5741 Palmer Way Carlsbad, California 92010 (760)438-3155 FAX (760)931-0915. www.geosoilsinc.com I February 11, 2011 I I Mr. Russell Bennett P.O. Box 356 Solana Beach, California 92075 W.O. 4147-A2-SC I Subject: Geotechnical Review of Grading Plans, .Lincoln and Oak Mixed Use, 3112 Lincoln Street, San Diego County,, California Dear Mr. Bennett: In accordance with your request and authorization, GeoSoils, Inc. (GSI) has performed a geotechnical review of the project grading plans, notes, and details prepared by Conway and Associates, Inc. (2011 [see the Appendix]), for the planned three-story mixed-use commercial and residential structure, as well as associated improvements at the subject site. The purpose of our review was to evaluate if the grading plans incorporate the recommendations provided in previous project geotechnical documents prepared by GSI (see Appendix), as required by EsGil Corporation (2010). GSI's scope of services included a review of Conway and Associates, Inc. (2011), EsGil Corporation (2010), GSI (2004a, 2004b, 2007, 2010, and 2011), and the preparation of this summary review letter. Recommendations contained in GSI (2004a, 2004b, 2007, 2010, and 2011), which are not specifically superceded by this review, should be properly incorporated into the design and construction phases of site development. Based on our review, the grading plans, and corresponding notes and details shown on Conway and Associates, Inc. (2011), appear to be in general accordance with the I recommendations provided in GSI (2004a, 2004b, 2007, 2010, and 2011), from a geotechnical standpoint, with the following comments: I GSI recommends that this review letter be referenced on Conway and Associates, Inc. (2011). I As previously indicated in GSI (2011), foundations should either be uniformly .- supported by unweathered terrace deposits or at least 2 feet of engineered fill. Foundations should not simultaneously bear on terrace deposits and compacted I . fill. . 0 I . If the client elects to support the footings on unweathered terrace deposits, and not performed complete site removals, GSI recommends that uniform support of the I interior slab-on-grade floors be provided by removing all unsuitable soils below a 1:1 (horizontal:vertical) projection below the bottom outside edge of the concrete slab to where the 1:1 plane intersects the surface of the relatively unweathered ten-ace deposits. Once the unsuitable soils have been removed, the resultant excavation should be observed by GSI. Following GSI observation and approval of the remedial grading excavation, the bottom of the excavation should be scarified at least 6 inches, moisture conditioned to at least the soil's optimum moisture content and re-compacted to at least 95 percent relative compaction (ASTM D 1557). The excavation may then be backlilled to planned grade with the removed soils that have been generally cleaned of organics and/or deleterious debris, placed in relatively thin lifts, moisture conditioned to at least optimum moisture content, and compacted to at least 95 percent relative compaction. The purpose of the 95 percent compaction requirement is to reduce the potential for differential settlement between slab-on-grade floors supported by engineered fill and footings supported by terrace deposits. Should the client elect to support the slabs and footings entirely on engineered fill, any terrace deposits located within 2 feet below the lowest foundation element (including elevator pits) following the removal of unsuitable soils, should be overexcavated at least 2 feet below the elevation of the bottom of the lowest footing. The overexcavation should be completed to a lateral distance of at least 5 feet outside the outboard-most foundation element, and the bottom of the overexcavation should be sloped to drain toward the street(s). Once the overexcavation is complete, the overexcavation bottom should be observed by GSI. Following the GSI overexcavation bottom observation and approval, the bottom of the overexcavation should be scarified at least 6 inches, moisture conditioned to at least the soil's optimum moisture content and re-compacted to at least 90 percent relative compaction. The overexcavation may then be backlilled to the planned grade with the removed and overexcavated soils that have been generally cleaned of organics and/or deleterious debris, placed in relatively thin lifts, moisture conditioned to at least optimum moisture content, and compacted to at least 90 percent relative compaction (ASTM D 1557). As indicated in GSI (2007), the California Building Code, removals of unsuitable soils be performed across all areas under the purview of the grading permit graded, not just within the influence of the proposed structures/buildings. Relatively deep removals may also necessitate a special zone: of consideration, on perimeter/confining areas. This zone would be approximately equal to the depth of removals, if removals cannot be performed offsite. Thus, any settlement-sensitive improvements (walls, curbs, flatwork, etc.), constructed within this zone may require deepened foundations, reinforcement, etc., or will retain some potential for settlement and associated distress. This will require proper disclosure to all. interested/affected parties, should this condition exist at the conclusion of grading: Mr. Russell Bennett • W.O. 4147-A2-SC Lincoln and Oak Mixed-Use Carlsbad • February 11, 2011 File: e:\wpl 2\4147\4147a2.gro • • • • Page 2 GeeSefls, Inc. I IJ I I [ I I I I I I I I I I Ii I I I I Detail 1 on Sheet 5 of Conway and Associates, Inc. (2011) indicates that the footing embedment for the building, Where located adjacent to the bottom of the bioretention swale should be measured relative to the bottom of the swale. GSI I recommends that the project civil and structural engineers coordinate the building locations where deepened footings are necessary. The project structural engineer should then show these locations and required footing depths on the foundation plan in order to minimize confusion during construction. GSI requests that revised plans (after the date of the plans reviewed herein) I showing the design of the fountain be provided'to this Office for review when they become available. Based on -our review amendments to the recommendations ' provided herein and in GSI (2004a, 2004b, 2007, 2010, and 2011) may be necessary. I . Provided that the above comments are properly incorporated into Conway and Associates, Inc. (2011), no further review, is deemed necessary. Should any amendments to the grading plans be hecessary following our review of the fountain I plans, they should be incorporated into the project drawings prior to construction. Should any major revisions pertaining to design layout and/or elevations be made following this review, GSI recommends that such revisions be reviewed bythis office I prior to construction. Based on our review of any significant plan revisions, GSI may recommend additional analysis. LIMITATIONS The conclusions and recommendations presented herein are professional opinions. These opinions have been derived in accordance with current standards of practice, and no warranty is express or implied. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. .. . . Iii I I Mr. Russell Bennett Lincoln and Oak Mixed Use Carlsbad FiIe:e:\wp124147\4147a2.gro. W.O. 4147-A2-SC February 11, 2011 Page 3 I . .. ., ,.. . GeoSoallsq- Inc. I I I I I U U U I I I I I I I I. I I SI I I I The opportunity to be of service is greatly appreciated. If you have any questions concerning this report, or if we may be of further assistance, please do not hesitate to contact any of the undersigned. Respectfully subn1ed— . . . . GeoSoils, In No. GE2320 110 Cor" fled Engineering eologist /1 I E uateIli eEngineering Geo t9 1340 . Geotechnical Engineer, GE 2320 /442 Ryan Boehmer Project Geologist RB/ATG/JPF/jh Attachment: Appendix - References S Distribution: (1) Addressee (via email) (4) Karnak Planning and Design, Attn: Robert Richardson (wet signed) (1) Concrode Consult Group, Inc., Attn: Kolaei Kripanarayanan (via email) (1) Conway and Associates, Attn: Mike Pasko (via email) Mr. Russell Bennett W.O. 4147-A2-SC Lincoln and Oak Mixed Use Carlsbad February 11, 2011 File:e:\wp12\4147\4147a2.gro Page 4 Inc. APPENDIX ' REFERENCES California Building Standards Commission, 2007, California Building Code. Conway and Associates, Inc., 2011, Grading plans for: Lincoln &Oak Mixed Use, Submittal No. 3, 6 sheets, 10-scale, Drawing No. 451-7A, Project No. CT 05-03, dated February 1. EsGil Corporation, 2010, Lincoln ,& Oak Mix Use, 3112 Lincoln Street, City of Carlsbad, Plan Check No. PCi 0-41, dated October 28. GeoSoils, Inc., 2011, Geotechnical review of foundation plans, Lincoln and Oak mixed use, 3112 Lincoln Street,' San Diego County, California, W.O. 4147-A3-SC, dated January 28. ' 2010, Geotechnical update for structural design, 3112 Lincoln Street, San Diego County, California, W.O. 4147-Al-SC, dated September 27. 2007, Geotechnical review of rough grading plans (first submittal), Lincoln and Oak Project, 3112 Lincoln Street, Carlsbad, San Diego County, California, W.O. 4147-A-SC, dated May 4. 2004a, Soil corrosivity results, 3112 Lincoln ,Street, Carlsbad, San Diego County, California, W.O. 4147-A-SC, dated January 22. 2004b, Preliminary geotechnical evaluation, 3112 Lincoln Street, Carlsbad, .,San Diego County, California, W.O. 4147-A-SC, dated January *14. ' eoSils Inc.