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HomeMy WebLinkAboutCDP 08-05; DUTT RESIDENCE; REPORT OF GEOTECHNICAL INVESTIGATION DUTTA; 2008-02-03CHR.IST1AN WHEELEFl ENGINEER.ING REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SINGLE-FAMILY RESIDENCE 6455 SURFSIDE LANE CARLSBAD, CALIFORNIA SUBMITTED TO: RAJ AND NAMITA DUTTA 7819 VISTA LAZANJA SAN DIEGO, CALIFORNIA 92127 RECEIVED FF CITY OF CARLSBAD PLANNING DEPT SUBMITTED BY: CHRISTIAN WHEELER ENGINEERING 4925 MERCURY STREET SAN DIEGO, CALIFORNIA 92111 4925 Mercury Street -f San Diego, CA 92111 • 858-496-9760 -f FAX 858-496-9758 CHF.ISTIAN WHEELER. ENGINEEB.ING August 16, 2007 Raj and Namita Dutta CVC'E 2070148.01 7819 Vista Lazanja San Diego, California 92127 SUBJECT: REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION, PROPOSED SINGLE-FAMILY RESIDENCE, 6455 SURFSIDE LANE, CARLSBAD, CALIFORNIA. Dear Mr. and Mrs. Dutta: In accordance with your request and our Proposal dated February 5, 2007, we have completed a geotechnical investigation for the subject property. In general, we found the subject site suitable to support the proposed single-family residence, provided the recommendations presented herein are followed. In general, no geotechnical conditions were encountered that would preclude the construction of the proposed residence provided the recommendations presented herein are followed. The site was found to be underlain b)^ Quaternary-age terrace deposits that are medium dense to very dense in consistency and are considered suitable to support settlement-sensitive improvements. Specific recommendations regarding the proposed construction are presented in the body of the attached report. The site is located in an area that is relatively free of geologic hazards that will have a significant effect on the proposed construction. The most likely geologic hazard that could affect the site is ground shaking due to seismic activity along one of the regional active faults. However, construction in accordance with the requirements of the most recent edition of the California Building Code and the local governmental agencies should provide a level of life-safety suitable for the type of development proposed. 492 5 Mercury Street • San Diego, CA 92111 • 858-496-9760 -f FAX 858-496-9758 CWTi 2070148.01 August 16, 2007 Page No. 2 Ifyou have any questions after reviewing this report, please do not hesitate to contact our office. This opportunit}- to be of professional service is sincerely appreciated. Respectfully submitted, CHRISTIAN WHEELER ENGINEERING ur W'ail Mokhtar, Staff Engineer Charles H. Christian, RGE # 00215 CHC:CRB:scc:wm as R. Burdett, C.E.G. #1090 cc: (2) Submitted (4) TETA Architecmre Inc. TABLE OF CONTENTS Page Introduction and Project Description 1 Project Scope 2 Findings 3 Site Description 3 General Geology and Subsurface Conditions 3 Geologic Setting and Soil Description 3 Groundwater 4 Tectonic Setting 4 Geologic Hazards 5 Ground Shaking 5 Landslide Potential and Slope Stability 5 Liquefaction 5 Flooding 6 Tsunamis 6 Seiches 6 Conclusions 6 Recommendations 7 Grading and Earthwork 7 General 7 Temporarv' Cut Slopes 7 Processing of Fill Areas 8 Compaction and Method of Filling 8 Surface Drainage 8 Grading Plan Review 8 Foundations 9 General 9 Conventional Foundations 9 Bearing Capacity 9 Footing Reinforcement 9 Lateral Load Resistance ; 9 Settiement Characteristics 9 Expansive Characteristics 10 Foundation Plan Review 10 Foundation Excavation Observation 10 Soluble Sufates 10 Seismic Design Parameters 10 On-Grade Slab 11 General 11 Interior Floor Slabs 11 Under-Slab Vapor Retarders 11 Exterior Concrete Flatwork 12 Earth Retaining Walls 13 Foundations 13 Passive Pressure 13 Equivalent Fluid Pressures 13 Waterproofing and Subdrain 13 Backfill Si3 Limitations 13 CWE 2070148.01 Proposed Single-Family Residence 6455 Surfside I.ane. Carlsbad, California Review, Obser\-ation and Testing 13 Uniformit}- of Conditions 14 Change in Scope 14 Tiine Limitations 14 Professional Standard 15 Client's Responsibilit}- 15 Field Explorations 15 Laboraton- Testing 16 ATTACHMENTS TABLES Table I Maximum Ground Acceleration, Page 5 Table II Seismic Design Parameters, Page 10 FIGURES Figure 1 Site Vicinity Map, Follows Page 1 PLATES Plate 1 Site Plan Plates 2-4 Boring Logs Plate 5 Laboratory Test Results Plate 6 Retaining Wall Subdrain Detail APPENDICES Appendix A References ^\.ppendix B Recommended Grading Specifications-General Provisions CW. 2070148.01 Proposed Single-Family Residence 6455 Surfside Lane, Carlsbad, California CHRISTIAN WHEELER. ENGINEERING REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SINGLE-FAMILY RESIDENCE 6455 SURFSIDE L.\NE CARLSBAD. CALIFORNIA INTRODUCTION AND PROJECT DESCRIPTION This report presents the results of a preliminary geotechnical investigation performed for a proposed single-family residence to be constructed at 6455 Surfside Lane, in the city of Carlsbad, California. Figure Number 1, presented on the following page, provides a site vicinity map showing the approximate location of the property. The subject site is a vacant, nearly rectangular-shaped residential lot. We understand that the property is to be developed by the construction of a two-story, single-famUy home with a fiill basement and a swimming pool. The above-grade portions of the proposed structure will be of wood-frame construction and the below-grade portion will be of masonry construction. The proposed structure is e-xpected to be supported by conventional shallow foundations with an on-grade concrete floor slab. Grading is expected to consist of making cuts of up to 10 feet from existing site grades for the proposed basement and new swimming pool. The basement will require retaining walls of up to about 10 feet in height. To assist in the preparation of this report, we were provided with a set of architectural plans for the proposed project, prepared by TETA Architecture, Inc., dated October 5, 2006. A copy of the proposed site plan was used as a base map for our site plan and geologic mapping, and is included herein as Plate No. 1. This report has been prepared for the exclusive use of Raj and Namita Dutta and their design consultants for specific application to the project described herein. Should the project be changed in an)- wa}-, the modified plans should be submitted to Christian Wlieeler Engineering for review to determine theu- conformance with our recommendations and to determine if any additional subsurface im-estigation, laborator}- testing and/or recommendations are warranted. Our professional services have been performed, our findings obtained, and our recommendations prepared in accordance with 4925 Mercury Street -f San Diego, CA 92111 • 858-496-9760 • FAX 858-496-9758 SITE VICINITY MAP (Adapted from Thomas Brothers Maps) PROPOSED SINGLE-FAMILY RESIDENCE 6455 SURFSIDE LANE CARLSBAD, CALIFORNIA SITE SOUTH CWE 2070148.01 August 2007 Figure 1 CWT: 2070148.01 August 16, 2007 Page No. 2 generally accepted engineering principles and practices. Tliis warrant}' is in lieu of aU other warranties, express or impUed. PROJECT SCOPE Our preUminan- geotechnical investigation consisted of surface reconnaissance, subsurface exploration, obtaining representative soil samples, laboratory testing, analysis of the field and laborator)- data and review of relevant geologic Uteramre. Our scope of service did not include assessment of hazardous substance contamination, recommendations to prevent floor slab moismre intrusion or the formation of mold within the strucmre, or any other services not specifically described in the scope of services presented below. More specifically, the intent of this investigation was to: a) Explore the subsurface conditions of the site to the depths influenced by the proposed construction; b) Evaluate, by laboratory tests and our experience with similar soils, the engineering properties of the various strata that may influence the proposed construction, including bearing capacities, expansive characteristics and settlement potential; c) Describe the general geology at the site including possible geologic hazards that could have an effect on the proposed construction, and provide the seismic design parameters as required by the most recent edition of the CaUfornia Building Code; d) Address potential construction difficulties that may be encountered due to soil conditions, groundwater or geologic hazards, and provide recommendations concerning these problems; e) Develop soil engineering criteria for site preparation and grading, and address temporary construction slopes; f) Provide design parameters for restrained and unrestrained retaining walls; C\XT: 2070148.01 August 16, 2007 Page No. 3 g) Recommend an appropriate foundation system for the type of structure anticipated and develop soil engineering design criteria for the recommended foundation design; h) Present our professional opinions in this report, which includes in addition to our conclusions and recommendations, a plot plan, exploration logs and a summar}' of the laboratory test results. Although a test for the presence of soluble sulfates within the soils that may be in contact with reinforced concrete was performed as part of the scope of our services, it should be understood Christian Wheeler Engineering does not practice corrosion engineering. If such an analysis is considered necessary, we recommend that the cUent retain an engineering firm that speciaUzes in this field to consult with diem on tiiis matter. The results of this test should only be used as a guideUne to determine if additional testing and analysis is necessary. FINDINGS SITE DESCRIPTION The subject site is a vacant, nearly rectangular-shaped parcel of land located at the address of 6455 Surfside Lane, m the city of Carlsbad, CaUfomia. The property is bounded on the east by Surfside Lane, on the north by Island Way, on the west by Carlsbad Boulevard, and on the south by a developed residential property. The property currendy supports masonry site waUs along the north, south, east, and a portion of the west property Unes. TopographicaUy, the lot is relatively level. Only sparse vegetation exists on the lot. GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located in the Coastal Plains Physiographic Province of San Diego County. Based on the results of our subsurface explorations and review of pertinent, readUy available geologic Uterature, we have determined that the site is underlain by Quaternary-age terrace deposits. Within our exploratory- borings, the terrace deposits were encountered at the surface and extended beyond the depths of our borings, which were each terminated at a depth of about 20 feet below the existing site grade. The encountered terrace deposits generally consisted of medium to dark brown and Ught to medium orangish-brown, CWE 2070148.01 August 16, 2007 Page No. 4 silt)- sand (SM), Ught brownish-gray, poorly-graded sand (SP), and medium orangish-brown, silt}^ sand-clayev sand (SM-SC). These deposits were generaUy damp to moist and medium dense to very dense in consistency. The existing terrace deposits are expected to possess a low expansion index and a low setdement potential in their present condition. The terrace deposits are considered suitable to support setdement-sensitive improvements. GROUNDWATER: No groundwater was encountered in our subsurface explorations and we do not expect any groundwater related conditions during or after the proposed construction. However, it should be recognized that minor groundwater seepage problems might occur after construction and landscaping at a site even where none were present before construction. These are usuaUy minor phenomena and are often the result of an alteration in drainage pattems and/or an increase in irrigation water. Based on the anticipated construction and landscaping, it is our opinion that any seepage problems that may occur wiU be minor in extent. It is further our opinion that these problems can be most effectively corrected on an individual basis if and when they occur. TECTONIC SETTING: No faults are known to traverse the subject site. However, it should be noted that much of Southem CaUfomia, including the San Diego County area, is characterized by a series of Quatemar}'-age fault zones that consist of several individual, en echelon faults that generaUy strike in a northerly to northwesterly direction. Some of these fault zones (and the individual faults within the zone) are classified as "active" according to the criteria of the CaUfomia Division of Mines and Geology. Active fault zones are those that have shown conclusive evidence of faulting during the Holocene Epoch (the most recent 11,000 years). The Division of Mines and Geology used the term "potentiaUy active" on Earthquake Fault Zone maps until 1988 to refer to aU Quatemary-age (last 1.6 milUon years) faults for the purpose of evaluation for possible zonation in accordance with the Alquist- Priolo Earthquake Fault Zoning Act and identified aU Quatemary-age faults as "potentiaUy active" except for certain faults that were presumed to be inactive based on direct geologic evidence of inactivity during aU of Holocene time or longer. Some faults considered to be "potentiaUy active" would be considered to be "active" but lack specific criteria used by the State Geologist, such as .uifftciently active and well-defined. Faults older than Quatemary-age are not specificaUy defined in Special PubUcation 42, Fault Rupmre Hazard Zones in CaUfomia, pubUshed by the CaUfornia Division of Mines and Geology. However, it is generaUy accepted that faults showing no movement during the Quaternan^ period may be considered to be "inactive". .\ review of available geologic maps indicates that the active Rose Canyon Fault Zone is located approximately 6 kUometers west of the subject site. Other active fault zones in the region that could CWE 2070148.01 August 16, 2007 Page No. 5 possibly affect the site include the Newport-Inglewood Fault Zone to tiie northwest, the Coronado Bank Fault Zone to the southwest, and the Elsinore and Earthquake VaUey Fault Zones to the northeast. GEOLOGIC HAZARDS GROUND SHAKING: A Ukely geologic hazard to affect die site is ground shaking as a result of movement along one of the major active fault zones mentioned above. The maximum ground accelerations that would be attributed to a maximum magnimde earthquake occurring along the nearest fault segments of selected fault zones that could affect the site are summarized in the foUowing Table I. TABL] E I: MAXIMUM GROUND ACCELERATION Fault Zone Distance Maximum Magnitude Earthquake Maximum Gtound Acceleration Rose Canyon 6 km 7.2 Magnitude 0.39 g Newport-Inglewood 11 km 7.1 Magnitude 0.27 g Coronado Bank 32 km 7.6 Magnitude 0.17 g Elsinore (JuUan) 41 km 7.1 Magnitude O.lOg Earthquake VaUey 69 km 6.5 Magnimde O.OSg Probable ground shaking levels at the site could range from sUght to moderate, depending on such factors as the magnitude of the seismic event and the distance to the epicenter. It is possible that the site wiU experience the effects of at least one moderate to large earthquake during the Ufe of the proposed improvements. LANDSLIDE POTENTIAL AND SLOPE STABILITY: As part of this investigation we reviewed die pubUcation, "LandsUde Hazards in the Northem Part of the San Diego MetropoUtan Area" by Tan, 1995. This reference is a comprehensive study that classifies San Diego County into areas of relative landsUde susceptibiUty. According to this pubUcation the site is situated within Relative LandsUde SusceptibiUty Area 2. Area 2 is considered to be "marginaUy susceptible" to slope failures; Area 2 includes gende to moderately sloping terrain, where slope faUure and landsUding occurrences are rare. Based on the competent nature of the underlying formational materials, and the level terrain of the site, it is our professional opinion that the potential for slope faUures within the site is very low. LIQUEFACTION: Tlie near-surface soUs encountered at the site are not considered susceptible to Uquefaction due to such factors as soU density, grain-size distribution, plasticity and the absence of shaUow groundwater conditions. CWE 2070148.01 August 16, 2007 Page No. 6 FLOODING: Tlie site is located outside the boundaries of both the 100-year and the 500-year floodplains according to the maps prepared by the Federal Emergency Management Agency. TSUNAMIS: Tsunamis are great sea waves produced by a submarine earthquake or volcanic eruption. HistoricaUy, the San Diego area has been free of tsunami-related hazards and tsunamis reaching San Diego have generaUy been weU within the normal tidal range. It is thought that the wide continental margin off the coast acts to diffuse and reflect the wave energy of remotely generated tsunamis. The largest historical tsunami to reach San Diego's coast was 4.6 feet high, generated by the 1960 earthquake in ChUe. A lack of knowledge about the offshore fault systems makes it difficult to assess the risk due to locaUy generated tsunamis. Due to the site's elevation and location, the risk of the site being affected by a tsunami is considered low. SEICHES: Seiches are periodic osciUations in large bodies of water such as lakes, harbors, bays or reservoirs. Due to the site's location, it should not be affected by seiches. CONCLUSIONS In general, no geotechnical conditions were encountered that would preclude the constmction of the proposed single-family residence provided the recommendations presented herein are foUowed. Based on our investigation, we have determined that the site is underlain by Quaternary-age terrace deposits that were found to be medium dense to very dense in consistency and are considered suitable to support settlement-sensitive improvements. Due to the proximity of the proposed fuU basement to the southern property Une, it may be necessary to shore the southern side of the basement excavation. Specific recommendations are presented in the "Temporary Cut Slopes" section of this report. The site is located in an area that is relatively free of geologic hazards that wiU have a significant effect on the proposed constmction. The most likely geologic hazard that could affect the site is ground shaking due to seismic activity along one of the regional active faults. However, constmction in accordance with the requirements of the most recent edition of the CaUfornia BuUding Code and the local governmental agencies should provide a level of Ufe-safety suitable for the t}'pe of development proposed. CWE 2070148.01 August 16, 2007 Page No. 7 RECOMMENDATIONS GRADING AND EARTHWORK GENERAL: We understand that site grading wiU be limited to making cuts of up to 10 feet from existing site grades for the proposed basement and new swimming pool. However, site preparation should begin with the removal of aU vegetation and other deleterious materials from the portions of the site that wUl receive improvements. The resulting materials should be disposed of off-site in a legal dumpsite. In addition, the upper 12 inches in areas to support exterior flatwork wUl need to be scarified. We anticipate that the excavations for the basement and pool wUl expose competent terrace deposits at the bottom of the excavations. The bottom of aU excavations should be approved by our project geologist, engineer, or technician supervisor prior to placing fiUs or constmcting improvements. No additional grading is expected during the proposed constmction. Our firm should be notified if the proposed plans change so that, if necessary, we may provide recommendations regarding die grading and earthwork of the modified project. TEMPORARY CUT SLOPES: Temporary cut slopes of up to about 10 feet in height are anticipated to be required during the constmction of the proposed basement Temporary cut slopes for the proposed basement retaining waUs can be excavated verticaUy for die bottom four feet and at an incUnation of 0.75 to 1.0 (horizontal to vertical) or flatter above. Our furm should be contacted to observe aU cut slopes during grading to ascertain diat no unforeseen adverse conditions exist. No surcharge loads such as soil or equipment stockpiles, vehicles, etc. should be aUowed within a distance from the top of temporary slopes equal to half the slope height. Wliere there is not room to constmct temporary slopes, temporary shoring of the excavation sides may be necessary. We anticipate that temporary shoring of tiie southern side of the excavation may be necessar}' to perform the cuts for the proposed basement. Shoring should be designed using the foUowing parameters. Angle of internal friction: 30 degrees Apparent cohesion: 300 psf Total Unit weight: 125 pcf CWE 2070148.01 August 16, 2007 Page No. 8 The contractor is solely responsible for designing and constmcting stable, temporar}^ excavations and may need to shore, slope, or bench the sides of trench excavations as required to maintain the stabiUt)- of the excavation sides. The contractor's "competent person", as defined in the OSlL-\ Construction Standards for Excavations, 29 CFR, Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safet}- process. Temporar)- cut slopes should be constmcted in accordance with the recommendations presented in this section. In no other case should slope height, slope incUnation, or excavation depth, including utiUty trench excavation depth, exceed those specified in local, state, and federal safet)' regulations. PROCESSING OF FILL AREAS: Prior to placing any new fiU soils or constmcting any new improvements in areas that have been cleaned out and approved to receive fUl, the exposed soils should be scarified to a depth of 6 inches, moisture-conditioned, and compacted to at least 90 percent relative compaction. No other special ground preparation is anticipated at this time. COMPACTION AND METHOD OF FILLING: AU stmctural fUl and backfUI material placed at the site should be compacted to a relative compaction of at least 90 percent of maximum dry density as determined by ASTM Laboratory Test D1557. FUls should be placed at or sUghtiy above optimum moisture content, in Ufts sbc to eight inches thick, with each Uft compacted by mechanical means. FUls should consist of approved earth material, free of trash or debris, roots, vegetation, or other materials determined to be unsuitable by our soil technicians or project geologist. FUl material should be free of rocks or lumps of soU in excess of twelve inches in maximum dimension. UtiUty trench backfiU within five feet of the proposed stmcture and beneath the driveway and concrete flatwork should be compacted to a minimum of 90 percent of its maximum dry density. SURFACE DRAINAGE: The ground around die proposed stmcture should be graded so that surface water flows rapidly away from the stmcture without ponding. In general, we recommend that the ground adjacent to stmctures slope away at a gradient of at least two percent. Densely vegetated areas where mnoff can be impaired should have a mirumum gradient of at least five percent within the first three feet from the stmcmre. Gutters and downspouts should discharge into controUed drainage devices. GRADING PLAN REVIEW: The final grading plan should be submitted to this office for review m order to ascertain that the recommendations contained in this report have been implemented, and rh at no additional recommendations are needed due to changes in the anticipated development plans CWE 2070148.01 August 16, 2007 Page No. 9 FOUNDATIONS GENERAL: Based on our findings and engineering judgment, it is our opinion that the proposed single-famUy residence may be supported by conventional continuous and isolated spread footings. The foUowing recommendations are considered the minimum based on soU conditions and are not intended to be Ueu of stmctural considerations. AU foundations should be designed by a quaUfied stmctural engineer. CONVENTIONAL FOUNDATIONS: Spread footings supporting the diree-story stmcmre should have a minimum embedment depth of 24 inches below pad grade. Continuous footings should have a minimum \vidth of 18 inches. Isolated and retaining waU footings should have a minimum width of 24 inches. Footings supporting exterior site waUs should be embedded at least 12 inches below the lowest adjacent grade and have a minimum width of 12 inches. BEARING CAPACITY: Conventional continuous spread footings with a minimum embedment of 12 inches and width of 12 inches may be designed for an aUowable soU bearing pressure of 2,500 pounds per square foot. This value may be increased by 700 pounds per square foot for each additional foot of embedment and 300 pounds per square foot for each additional foot of width up to a maximum of 5,000 pounds per square foot. The bearing value may also be increased by one-third for combinations of temporary loads such as those due to wind or seismic loads. FOOTING REINFORCEMENT: The project stmctural engineer should provide reinforcement requirements for foundations. However, based on soil conditions, we recommend tiiat the minimum reinforcing for continuous footings should consist of at least one No. 5 bar positioned three inches above the bottom of the footing and one No. 5 bar positioned two inches below the top of the footing. LATERAL LOAD RESISTANCE: Lateral loads against foundations may be resisted by friction between the bottom of the footing and the supporting soU, and by the passive pressure against the footing. The coefficient of friction between concrete and soil may be considered to be 0.30. The passive resistance may be considered to be equal to an eqiuvalent fluid weight of 350 pounds per cubic foot. This assumes the footings are poured tight against undismrbed soU. If a combination of the passive pressure and friction is used, the friction value should be reduced by one-third. SETTLEMENT CHARACTERISTICS: The anticipated total and differential foundation settlement is expected to be less than about 1 inch and 1 inch in 40 feet, respectively, provided the CWT. 2070148.01 August 16, 2007 Page No. 10 recommendations presented in our forthcoming report are foUowed. It should be recognized that minor cracks normally occur in concrete slabs and foundations due to shrinkage during curing or redistribution of stresses, therefore some cracks may be anticipated. Such cracks are not necessarUy an indication of excessive vertical movements. EXPANSIVE CHARACTERISTICS: The existing soUs are expected to have a low expansive potential. The recommendations presented in this report reflect this condition. FOUNDATION PLAN REVIEW: The foundation plans should be submitted to diis office for review in order to ascertain that the recommendations of this report have been implemented, and that no additional recommendations are needed due to changes in the anticipated constmction. FOUNDATION EXCAVATION OBSERVATION: AU foundation excavations should be observed by a representative of this office prior to the placement of forms or reinforcement in order to verif)' that the footings have the proper dimensions and that the soU conditions are as anticipated during the formation of our foundation recommendations. SOLUBLE SUFATES The water soluble sulfate content was determined for a representative soU sample from the site in accordance with CaUfornia Test Method 417. The results of this test indicate that the representative soU sample had a soluble sulfate content of less than 0.001 percent. SoUs with a soluble sulfate content of less than 0.1 percent are considered to be neghgible and no special recommendations are needed. SEISMIC DESIGN PARAMETERS Based on our Deterministic Seismic Hazard Analysis, the Maximum Ground Acceleration at the site is estimated to be 0.39 g (based upon a Maximum Magnimde Seismic Event of 7.2 Magnimde along the Rose Canyon Fault). For stmctural design purposes, a damping ratio not greater than 5 percent of critical dampening, and SoU Profile Type Sc are recommended (CBC Table 16-J). Based upon the location of the site at approximately 6 kUometers from the Rose Canyon Fault (T}'pe B Fault), Near Source Factors N-, equal to 1.00 and Nv equal to 1.16 are also appUcable. These values, along with other seismicaUy related design parameters from the CaUfomia Building Code (CBC) 1997 edition, Volume II, Chapter 16, utiUzing a Seismic Zone 4 are presented in tabular form below. CWT: 2070148.01 August 16, 2007 Page No. 11 TABLE II: SEISMIC DESIGN PARAMETERS CBC Chapter 16 Seismic Recommended Table No. Parameter Value 16-1 Seismic Zone Factor Z 0.40 16-J SoU ProfUe T}'pe Sc 16-Q Seismic Coefficient Ca 0.40 Na 16-R Seismic Coefficient Cy 0.56 Nv 16-S Near Source Factor Na 1.00 16-T Near Source Factor Nv 1.16 16-U Seismic Source Type B ON-GRADE SLAB GENERAL: It is our understanding that the floor system for the proposed stmcture wiU consist of a concrete slab-on-grade floor. The foUowing recommendations are considered the niinimum slab requirements based on the soU conditions and are not intended in Ueu of stmctural considerations. INTERIOR FLOOR SLAB: The minimum floor slab thickness should be four inches (actual) and the floor slab should be reinforced with at least No. 3 reinforcing bars placed at 18 inches on center each way. Slab reinforcement should be supported on chairs such that the reinforcing bars are positioned at mid-height in the floor slab. The slab reinforcement should extend into the perimeter foundations at least six inches. UNDER-SLAB VAPOR RETARDERS: Steps should be taken to minimize the transmission of moismre vapor from the subsoU through the interior slabs where it can potentiaUy damage the interior floor coverings. Local industry standards typicaUy include the placement of a vapor retarder, such as visqueen, between two, 2-inch-thick layers of coarse sand placed direcfly beneath the concrete slab. Tliis is the most common under-slab vapor retarder system used in San Diego County. The vapor retarder should be at least 15-mU visqueen with sealed seams and should extend at least 12 inches down the sides of the interior and perimeter footings. The sand should contain less than 10% passing the Number 100 sieve and less than 5% passing the Number 200 sieve. Although the system described above has historicaUy performed adequately, national standards for the installation of vapor retarders below interior slabs are changing as evidenced in currently pubUshed standards including ACI 302, "Guide to Concrete Floor and Slab Construction" and .\STM El 643, "Standard Practice for InstaUation of Water Vapor Retarder Used in Contact with I 'arth or Granular FiU Under Concrete Slabs". Rather than placing the vapor retarder between the CWT, 2070148.01 August 16, 2007 Page No. 12 t\vo sand layers, both of these standards recommend placing the sand capUlary break layer onto the subgrade with a vapor retarder placed above the sand and the concrete placed directly onto the vapor retarder. There are advantages and disadvantages to each of these installation procedures. An advantage to placing concrete directiy onto a vapor retarder is that it eUminates the layer of sand between the slab and vapor retarder. This layer of sand t)'picaUy contains moisture prior to the placement of concrete and can receive more moisture during the curing and constmction processes. This moismre can be retained in the sand layer for an extended period of time until the concrete moisture decreases to the point at which the excess sand moisture is absorbed by the concrete and transmitted up through the slab. This process can take many months depending upon the environmental conditions. One disadvantage to placing concrete directiy onto a vapor retarder is that removing the sand layer from directly beneath the concrete restricts the abUity of the concrete to lose moistore on both the top and bottom surfaces during the initial curing period. Variations in the drying rate between the top and bottom surfaces can result in increased concrete cracking, curUng, and other finishing issues. The drying rate differences and their potential side effects can be minimized, however, with suitable finishing and curing procedures. Recognizing the stated benefits and limitations of these standard below-slab vapor retarder systems, the owner and designer should select the system that they beUeve is most suitable for this project considering the constmction schedule and planned floor coverings. It should be understood that neither of the described systems provides a "waterproof barrier". It should also be understood that slab concrete contains free water and should be aUowed to reach equiUbrium in an environment simUar to that anticipated in the completed stmctore prior to instaUing floor coverings. We recommend that the flooring instaUer perform standard moisture vapor emission tests prior to the instaUation of aU moistore-sensitive floor coverings in accordance with ASTM F1869 "Standard Test Method for Measuring Moistore Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride". EXTERIOR CONCRETE FLATWORK: Exterior slabs should have a minimum thickness of four inches. Reinforcement should be placed in exterior concrete flatwork to reduce the potential for cracking and movement. Control joints should be placed in extenor concrete flatwork to help control rile location of shrinkage cracks. Spacing of control joints should be m accordance with the i\merican CWE 2070148.01 August 16, 2007 Page No. 13 Concrete Institote specifications. W'here patio slabs, walkways and porch slabs abut perimeter foundations, they should be doweled into the footings. EARTH RETAINING WALLS FOUNDATIONS: Foundations for proposed retaining waUs should be constructed in accordance with the foundations recommendations presented previously in diis report. PASSIVE PRESSURE: The passive pressure for the design of sUding resistance for retaining waUs may be considered to be 350 pounds per square foot per foot of embedment. These pressures may be increased one-third for seismic loading. The coefficient of friction for concrete to fiU soU may be assumed to be 0.30 for the resistance to lateral movement. EQUIVALENT FLUID PRESSURES: The lateral soU pressure for the design of "unrestrained" and "restrained" earth retaining stmctares with level backfiU may be assumed to be equivalent to the pressure of a fluid weighing 35 and 55 pounds per cubic foot, respectively. These pressures do not consider any surcharge. If any are anticipated, this office should be contacted for the necessary increase in soU pressure. These values also assume a drained, non-detrimentally expansive (E.I.<50) backfiU condition. WATERPROOFING AND SUBDRAIN: Waterproofing detaUs should be provided by die project arcliitect. A suggested waU subdrain detaU is provided m Plate Number 6. We recommend that the Geotechnical Consultant observe aU retaining waU subdrains to verify proper constmction. BACKFILL: All backfiU soUs should be compacted to at least 90 percent relative compaction. Expansive or clayey soUs should not be used for backfiU material. The waU should not be backfiUed untU the masonr}' has reached an adequate strength. LIMITATIONS REVIEW, OBSERVATION AND TESTING The recommendations presented in this report are contingent upon our review of final plans and specifications. Such plans and specifications should be made avaUable to the Geotechnical Engineer and tiiginecring Geologist so that they may review and verify their compUance with this report and CWE 2070148.01 August 16, 2007 Page No. 14 with the CaUfornia BuUding Code. It is reconimended tiiat Christian Wlieeler Engineering be retained to provide continuous soU engineering services during the earthwork operations. Tliis is to verif)' compUance with the design concepts, specifications or recommendations and to aUow design changes in the event that subsurface conditions differ from those anticipated prior to start of constmction. UNIFORMITY OF CONDITIONS The recommendations and opinions expressed in this report reflect our best estimate of tiie project requirements based on an evaluation of the subsurface soU conditions encountered at the subsurface exploration locations and on the assumption that the soU conditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations and/or cut and fiU slopes may be influenced by undisclosed or unforeseen variations in the soU conditions that may occur in the intermediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site development should be brought to the attention of the Geotechnical Engineer so that he may make modifications if necessary. CHANGE IN SCOPE This office should be advised of any changes in the project scope or proposed site grading so that we may determine if the recommendations contained herein are appropriate. It should be verified in writing if the recommendations are found to be appropriate for the proposed changes or our recommendations should be modified by a written addendum. TIME LIMITATIONS Tlie findings of this report are vaUd as of this date. Changes in die condition of a property can, however, occur vvith the passage of time, whether they are due to natoral processes or the work of man on this or adjacent properties. In addition, changes in the Standards-of-Practice and/or Govemment Codes may occur. Due to such changes, the findings of this report may be invaUdated whoUy or in part by changes beyond our control. Therefore, this report should not be reUed upon after a period of two years without a review by us verifying the suitabUity of the conclusions and recommendations. CWT. 2070148.01 i\ugust 16, 2007 Page No. 15 PROFESSIONAL STANDARD In the performance of our professional services, we comply with that level of care and skUl ordinarily exercised by members of our profession currendy practicing under simUar conditions and in tiie same locaUr\-. The cUent recognizes that subsurface conditions may vary from those encountered at the locations where our borings, surveys, and explorations are made, and that our data, interpretations, and recommendations are based solely on the information obtained by us. We wUl be responsible for those data, interpretations, and recommendations, but shaU not be responsible for the interpretations by others of the information developed. Our services consist of professional consultation and observation only, and no warrant)' of any kind whatsoever, express or impUed, is made or intended in connection with the work performed or to be performed by us, or by our proposal for consulting or other services, or by our furnishing of oral or written reports or findings. CLIENT'S RESPONSIBILITY It is the responsibUity of the CUent, or their representatives, to ensure that the information and recommendations contained herein are brought to the attention of the stmctoral engineer and architect for the project and incorporated into the project's plans and specifications. It is further their responsibUit}' to take the necessary measures to insure that the contractor and his subcontractors carry out such recommendations during constmction. FIELD EXPLORATIONS Three subsurface explorations were made on July 24, 2007 at the locations indicated on the attached Plate Number 1. These explorations consisted of borings driUed with a CME 55 driU rig using a hollow-stem auger. The fieldwork was conducted under the observation of our engineering geology personnel. The explorations were carefuUy logged when made. The boring logs are presented on the foUowing Plate Numbers 2 through 4. The soUs are described in accordance with the Unified SoUs Classification System. In addition, a verbal textoral description, the wet color, the apparent moistore and thc density- or consistency are provided. The density of granular soils is given as very loose, loose, medium dense, dense or very dense. The consistency of sUts or clays is given as either verv soft, soft, medium stiff, stiff, very stiff, or hard. CWT. 2070148.01 August 16, 2007 Page No. 16 Relatively undismrbed drive samples were coUected using a modified CaUfornia sampler. The sampler, with an external diameter of 3.0 inches, is Uned with 1-inch long, thin, brass rings with inside diameters of approximately 2.4 inches. The sample barrel was driven into the ground with the w-eiglit of a 140-pound hammer faUing 30 inches in general accordance with ASTM D 3550-84. The driving weight is perniitted to faU freely. The number of blows per foot of driving, or as indicated, are presented on the boring logs as an Uidex to the relative resistance of the sampled materials. The samples were removed from the sample barrel in the brass rings, and sealed. Bulk samples of the encountered earth materials were also coUected. Samples were transported to our laboratory for testing. LABORATORY TESTING Laborator}' tests were performed in accordance with the generaUy accepted American Society for Testing and Materials (ASTM) test methods or suggested procedures. A brief description of the tests performed is presented below: a) CLASSIFICATION: Field classifications were verified in the laboratory by visual examination. The final soU classifications are in accordance with the Unified SoU Classification System. b) MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT TEST: The maximum dry density and optimum moistore content of a sample of the on-site soU was determined in the laboratory in accordance with ASTM Standard Test D-1557, Method A. The results of this test are presented on Plate No. 5. c) MOISTURE-DENSITY: In-place moistare contents and dry densities were determined for representative soU samples. This information was an aid to classification and permitted recognition of variations in material consistency with depth. The dry unit weight is determined in pounds per cubic foot, and the in-place moistore content is determined as a percentage of the soU's dry weight. The results are summarized in the boring logs. d) DIRECT SHEAR TEST: Two direct shear tests were performed to determine the failure envelope of representative samples of the on-site soU based on yield shear strength. The shear box was designed to accommodate a sample having a diameter of 2.375 inches CWT 2070148.01 August 16, 2007 Page No. 17 or 2.50 inches and a height of 1.0 inch. Samples were tested at different vertical loads and a saturated moistore content. The shear stress was appUed at a constant rate of strain of approximately 0.05 inch per minute. The results of these tests are presented on Plate No. 5. e) SOLUBLE SULFATES: The soluble sulfate content was determined for a sample of soU Ukely to be present at the foundation level. The soluble sulfate content was detemiined in accordance widi CaUfomia Test Method 417. The results are presented on Plate No. 5. f) GRAIN SIZE DISTRIBUTION: The grain size distribution was determined from a representative soU sample in accordance with ASTM D422. The results of this test are presented on Plate No. 5. Date Excavated: Equipnient: Existing Elevation: Finish Elevation; LOG OF TEST BORING NUMBER B-l 7/24/2007 Logged by: CME-55 Assumed 100 feet 90 feet AIvN Project Manager: CHC Depth to Water: N/A Drive Weight: 140 lbs. SUMNL\RY OF SUBSURFACE CONDITIONS S.VMPl.IvS H c/3 o l-H Q 00 - 4 - 6 Terrace Deposits (Qt): Medium to dark brown to orangish-brown, damp to moist, dense to very dense, SILTY SAND (SM), fine to medium-grained, with trace clay binder, slightly mottled. At 3 feet becomes light to medium orangish-brown. Cal Cal 50/5" r,9 MD SS DS DS - 10 12 - 14 - 16 - 18 1-20 Light brownish-gray, damp to moist, dense, POORLY, GRADED SAND (SP), fine to medium-grained, friable. .\t 13 feet becomes moist and medium dense to dense. .\t 17 feet becomes dense. Cal 50/6" 7.1 115.3 SA Cal 45 2.8 102.9 Cal 64 Test boring terminated at 20 feet. No groundwater or seepage PROPOSED SINGLE FAMILY RESIDENCE 6455 Surfside Lane, Carlsbad, California CHRI^n.W VVHFELFR BY: MW JOB NO. 2070148 DATE: August 2007 PL.\TE NO.: Date Excavated: F'quipnient: Existing Elevation: Finish Elevation; LOG OF TEST BORING NUMBER B-2 7/24/2007 Logged by: CME-55 Assumed 100 feet 90 feet AKN Project Manager: CHC Depth to Water: N/A Drive Weight: 140 lbs. c2 o SUM\L\RY OF SUBSURFACE CONDITIONS .'^.VMPI.liS D H I—I o HH C> Pi Q - 4 - 6 - 10 12 - 14 - 16 - 1! Terrace Deposits (Ot): Light to medium orangish-brown, damp to moist, dense, SILTY SAND (SM), fme to medium-grained, slightly mottled. Contact at 872 feet. Light grajish-brown, damp to moist, medium dense to dense, POORLY, GR-\DED SAND (SP), fme to medium-grained, with Fe staining throughout. At 12 feet becomes dense. Cal Cal 50/6" 5.0 112.7 58 4.4 110.0 Cal Cal Co.\ .14 102.3 68 67 Test boring terminated at 20 feet. No groundwater or seepage. m CIIRL^IIAX WHFFLER 1 N 1 , 1 N 1 I K 1 \ ( , PROPOSED SINGLE FAMILY RESIDENCE 6455 Surfside Lane, Carlsbad, California m CIIRL^IIAX WHFFLER 1 N 1 , 1 N 1 I K 1 \ ( , BY: MW DATE: August 2007 m CIIRL^IIAX WHFFLER 1 N 1 , 1 N 1 I K 1 \ ( , JOB NO. : 2070148 PL.\TE NO.: 3 Date Excavated: Equipment: Existing Elevation: Finish Elevation: LOG OF TEST BORING NUMBER B-3 7/24/2007 Logged by: CME-55 Assumed 100 feet 90 feet AI<N Project Manager: CHC Depth to Water: N/A Drive W^eight: 140 lbs. Q y SUMmRY OF SUBSURFACE CONDITIONS S.\MP1,I'.S < oo P-l S. Z ^ PH D H l-H o D ^ Q H c/2 W H _ 0 - 4 - 10 12 - 14 16 18 1-20 Terrace Deposits (Ot): Medium to dark brown, damp to moist, dense, SILT\' SAND (SM), fme to medium-grained, with trace clay binder, mottled. c;ai 50/5" Medium orangish-brown, moist, medium dense, SILTY SAND- CLA\TY S.\ND (SM-SC), fme to medium-grained, sUghtly mottied. Cal Cal 43 62 Light brownish-gray, moist, dense, POORLY, GRADED SAND (SP), fine to medium-grained. f;al 74 Cal 58 Test boring terminated at 20 feet. No groundwater or seepage. PROPOSED SINGLE FAMILY RESIDENCE 6455 Surfside Lane, Carlsbad, California CHRIS11AN WHEELER I \ f, I \ I I K I N (, BY; MW JOB NO. : 2070148 DATE: August 2007 PLATE NO.; LABORATORY TEST RESULTS PROPOSED SINGLE-FAMILY RESIDENCE 6455 SURFSIDE L.\NE CARLSBAD. CALIFORNIA MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT (ASTM D1557) Sample Location: Boring B-l @ 0'-8.5' Sample Description: Reddish-brown, SM Maximum Densit)-; 127.4 pcf Optimvim Moisture: 9.3 "'b DIRECT SHEAR (ASTM D3080) Sample Location: Boring B-l @ 0'-8.5' Boring B-l @ 5' Sample Type: Remolded to 90 % Natural Friction Angle; 28 ° 29 ° Cohesion; 150 psf 300 psf GRAIN SIZE DISTRIBUTION (ASTM D422) Sample Location Boring B-l @ 9'-18.5' Sieve Sit^e Percent Passing #4 100 #8 100 #16 100 #30 92 #50 37 #100 . 9 #200 5 SOLUBLE SULFATES (CALIFORNLA TEST 417) Sample Location: Boring B-l @ 0'-8.5' Soluble Sulfate; < 0.001 % (SO4) (:\\ I 2( I7( 1148.1) 1 August 2007 Plate No. 5 Slope Minimum 3/4 inch Crushed Rock or Miradram 6000 or Equivalent Geofabric Between Rock and Soil Minimum 4-inch Diameter Perforated Pipe P\'C Schedule 40 6-incli t Max. 12" 6-inth Mimmum r Waterproof Back of WaU Per Architect's Specifications Top of Ground or Concrete Slab / 6-inch Minimum RETAINING WALL SUBDRAIN DETAIL No Scale w I IKMI\N Wl II i )'l I .1 ). . \! II I il.'M \ ''21 Tl 4')', TCli I ;\,\, («.5Sj 4')(, 97.i« PROPOSED SINGLE-FAMILY RESIDENCE 645S SURFSIDE LANE CARLSBAD, CALIFORNIA Sll\' |()H\C).: 2070I4S.III DATI-; l'l.,\ ri-. N( ).: August 2007 CWT 2070148.01 August 16, 2007 Appendix A REFERENCES Anderson, J.G.; RockweU, R.K. and Agnew, D.C, 1989, Past and Possible Futore Earthquakes of Significance to the San Diego Region, Earthquake Spectra. Volume 5, No. 2, 1989. Blake, T.F., 2000, EQFAULT, A Computer Program for the Estimation of Peak Horizontal Acceleration from 3-D Fault Sources, Version 3.0, Thomas F. Blake Computer Services and Software, Thousand Oaks, CaUfornia. Boore, David M., Joyner, WUUam B., and Fumal, Thomas E., 1997, "Empirical Near-Source Attenuation Relationships for Horizontal and Vertical Components of Peak Ground Acceleration, Peak Ground Velocity, and Pseudo-Absolute Acceleration Response Spectra", in Seismological Research Letters, Volume 68, Number 1, January/Febmary 1997. Count)'wide Flood Insurance Rate Map, Map No. 06073C1027 F (panel 1027F of 2375), prepared by the Federal Emergency Management Agency, effective date June 19, 1997. Cahfornia Division of Mines and Geology, 1998, Maps of Known Active Fault Near-Source Zones in Cahfomia and Adjacent Portions of Nevada. Jennings, C.W., 1975, Fault Map of CaUfornia, CaUfornia Division of Mines and Geology, Map No. 1, Scale 1:750,000. Kennedy, M.P., 1975, Geology of the San Diego MetropoUtan Area, CaUfornia; CaUfomia Division of Mines and Geology, BuUetin 200. Kennedy, M.P., 1980, Recency and Character of Faulting Offshore MetropoUtan San Diego, CaUfornia; CaUfomia Division of Mines and Geology, Map Sheet 40. Kern, P., 1989, Earthquakes and Faults in San Diego County, Pickle Press, 73 pp. Wesnousky, S.G., 1986, "Earthquakes, Quaternary Faults, and Seismic Hazards in CaUfornia," in Journal of Geophysical Research, Volume 91, No. B12, pp 12,587 to 12,631, November 1986. Tan, S.S., 1995, LandsUde Hazards in the Northern Part of the San Diego MetropoUtan Area, San Diego CounU', CaUfornia, CaUfornia Division of Mines and Geology Open-File Report 95-03. CWT 2070148.01 August 16, 2007 Appendix A CWT 2070148.01 August 16, 2007 Appendix B - 1 RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS PROPOSED SINGLE-FAMILY RESIDENCE 6455 SURFSIDE LANE CARLSBAD. CALIFORNIA GENERAL INTENT The intent of these specifications is to estabUsh procedures for clearing, compacting natoral ground, preparing areas to be fiUed, and placing and compacting fiU soUs to the Unes and grades shown on the accepted plans. The recommendations contained in the preUminary geotechnical investigation report and/or the attached Special Provisions are a part of the Recommended Grading Specifications and shaU supersede the provisions contained hereinafter in the case of conflict. These specifications shaU only be used m conjunction with the geotechnical report for which they are a part. No deviation from these specifications wUl be aUowed, except where specified in the geotechnical report or in other written communication signed by the Geotechnical Engineer. OBSERVATION AND TESTING Christian Wlieeler Engineering shaU be retained as the Geotechnical Engineer to observe and test the earthwork in accordance witii these specifications. It wUl be necessary tiiat the Geotechnical Engineer or his representative provide adequate observation so that he may provide his opinion as to whether or not the work was accompUshed as specified. It shaU be die responsibUity of the contractor to assist the Geotechnical Engineer and to keep hkn appraised of work schedules, changes and new information and data so that he may provide these opinions. In the event that any unusual conditions not covered by the special provisions or preUminar)' geotechnical report are encountered during the grading operations, the Geotechnical Engineer shall be contacted for further recommendations. If in the opinion of the Geotechnical Engineer, substandard conditions are encountered, such as questionable or unsuitable soU, unacceptable moistore content, inadequate compaction, adverse weather, etc., construction should be stopped untU the conditions are remedied or corrected or he shaU recommend rejection of this work. Tests used to determine the degree of compaction should be performed in accordance with the following .\n-ierican Societ)- for Testing and Materials test methods: CWT 2070148.01 August 16, 2007 Appendix B - 2 Maximuni Density- & Optimum Moistore Content - ASTM D-1557-91 Density- of SoU In-Place - ASTM D-1556-90 or ASTM D-2922 AU densities shall be expressed in terms of Relative Compaction as determined by the foregoing ASTM testing procedures. PREPARATION OF AREAS TO RECEIVE FILL AU vegetation, brush and debris derived from clearing operations shaU be removed, and legaUy disposed of All areas distorbed by site grading should be left in a neat and finished appearance, free from unsightiy debris. After clearing or benching the natoral ground, the areas to be fiUed shaU be scarified to a depth of 6 inches, brought to the proper moistore content, compacted and tested for the specified minimum degree of compaction. AU loose soUs in excess of 6 inches thick should be removed to firm natoral ground which is defined as natoral soil which possesses an in-sita density of at least 90 percent of its maximum dry density. Wlien the slope of the natoral ground receiving fiU exceeds 20 percent (5 horizontal units to 1 vertical unit), the original ground shaU be stepped or benched. Benches shaU be cut to a furm competent formational soU. The lower bench shaU be at least 10 feet wide or 1-1/2 times the equipment width, whichever is greater, and shall be sloped back into the hiUside at a gradient of not less than two (2) percent. AU other benches should be at least 6 feet wide. The horizontal portion of each bench shaU be compacted prior to receiving fiU as specified herein for compacted natoral ground. Ground slopes flatter than 20 percent shaU be benched when considered necessary by the Geotechnical Engineer. Any abandoned buried structores encountered during grading operations must be totaUy removed. AU underground utiUties to be abandoned beneath any proposed stmctore should be removed from within 10 feet of the structure and properly capped off The resulting depressions from the above described procedure should be backfiUed with acceptable soU that is compacted to the requirements of the Geotechnical Engineer. This includes, but is not limited to, septic tanks, fuel tanks, sewer Unes or leach Unes, storm drains and water Unes. Any buried structores or utiUties not to be abandoned should be brought to the attention of the Geotechnical Engineer so that he may determine if any special recommendation wiU be necessary. .Ml water weUs which wiU be abandoned should be backfiUed and capped in accordance to the requkements set torth by the Geotechnical Engineer. The top of the cap should be at least 4 feet below finish grade or 3 CWT 2070148.01 August 16, 2007 Appendix B - 3 feet below the bottom of footing whichever is greater. The type of cap will depend on the diameter of the well and should be determined by the Geotechnical Engineer and/or a quahfied Stmctural Engineer. FILL MATERIAL Materials to be placed in the fiU shaU be approved by the Geotechnical Engineer and sliaU be free of vegetable matter and other deleterious substances. Granular soU sliaU contain sufficient fine material to fiU the voids. The definition and disposition of oversized rocks and expansive or detrimental soils are covered in the geotechnical report or Special Provisions. Expansive soUs, soils of poor gradation, or soUs with low strength characteristics may be thoroughly mixed with other soUs to provide satisfactory fiU material, but only with the expUcit consent of the Geotechnical Engineer. Any import material shaU be approved by the Geotechnical Engineer before being brought to the site. PLACING AND COMPACTION OF FILL Approved fiU material shaU be placed in areas prepared to receive fill in layers not to exceed 6 inches in compacted thickness. Each layer shaU have a uniform moistore content ia the range that wiU allow the compaction effort to be efficiendy appUed to achieve the specified degree of compaction. Each layer shaU be uniformly compacted to the specified minimum degree of compaction with equipment of adequate size to economically compact the layer. Compaction equipment should either be specifically designed for soU • compaction or of proven reUabUity. The minimum degree of compaction to be achieved is specified in either the Special Provisions or the recommendations contained in the preUminary geotechnical investigation report. Wlien the stmctoral fiU material includes rocks, no rocks wUI be aUowed to nest and aU voids must be carefully fiUed with soU such that the minimum degree of compaction recommended in the Special Provisions is achieved. The maximum size and spacing of rock permitted in stmctoral fiUs and in non-stmctaral fiUs is discussed in the geotechnical report, when appUcable. Field observation and compaction tests to estimate the degree of compaction of the fiU wiU be taken by the Geotechnical Engineer or his representative. The location and frequency of the tests shaU be at the Geotechnical Engineer's discretion. When the compaction test indicates that a particular layer is at less than thc required degree of compaction, the layer shaU be reworked to the satisfaction of the Geotechnical Fiigineer and until the desired relative compaction has been obtained. FiU slopes shaU be compacted by means of sheepsfoot roUers or other suitable equipment. Compaction by sheepsfoot roller shaU be at vertical intervals of not greater than four feet. In addition, fill slopes at a ratio of CWT 2070148.01 August 16, 2007 Appendix B - 4 two horizontal to one vertical or flatter, should be trackroUed. Steeper fUl slopes sliaU be over-buUt and cut- back to finish contours after the slope has been constmcted. Slope compaction operations shaU result in aU fill material six or more inches inward from the finished face of the slope having a relative compaction of at least 90 percent of maximum dry density or the degree of compaction specified in the Special Provisions section of this specification. The compaction operation on the slopes sliaU be continued until the Geotechnical Engineer is ofthe opinion that the slopes wiU be surficially stable. Density tests in the slopes wiU be made by the Geotechnical Engineer during constmction of the slopes to determine if the required compaction is being achieved. Where faiUng tests occur or other field problems arise, the Contractor wiU be notified that day of such conditions by written communication from tiie Geotechnical Engineer or his representative in the form of a daUy field report. If the method of achieving the required slope compaction selected by the Contractor faUs to produce the necessary results, the Contractor shaU rework or rebuUd such slopes untU the required degree of compaction is obtained, at no cost to the Owner or Geotechnical Engineer. CUT SLOPES The Engineering Geologist shaU inspect cut slopes excavated in rock or Uthified formational material during the grading operations at intervals determined at his discretion. If any conditions not anticipated in the preUminary report such as perched water, seepage, lenticular or confined strata of a potentiaUy adverse natare, unfavorably incUned bedding, joints or fault planes are encountered during grading, these conditions shaU be analyzed by the Engineering Geologist and Geotechnical Engineer to determine if mitigating measures are necessary. Unless otherwise specified in the geotechnical report, no cut slopes shaU be excavated higher or steeper than that allowed by the ordinances of the controUing govemmental agency. ENGINEERING OBSERVATION Field observation by the Geotechnical Engineer or his representative shall be made during the fUUng and compaction operations so that he can express his opinion regarding the conformance of the grading with acceptable standards of practice. Neither the presence of the Geotechnical Engineer or his representative or thc obseri-ation and testing shaU release the Grading Contractor from his duty to compact aU fiU material to rhe specified degree of compaction. CWT 2070148.01 August 16, 2007 Appendix B - 5 SEASON LIMITS Fill shall not be placed during unfavorable weather conditions. When work is interrupted by hea\'y rain, filUng operations shaU not be resumed untU the proper moistare content and density of the fiU materials can be achieved. Damaged site conditions resulting from weather or acts of God shaU be repaired before acceptance of work. RECOMMENDED GRADING SPECIFICATIONS - SPECIAL PROVISIONS RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted natoral ground, compacted fiU, and compacted backfdl shaU be at least 90 percent. For street and parking lot subgrade, the upper twelve inches should be compacted to at least 95 percent relative compaction. EXPANSIVE SOILS: DetrimentaUy expansive soU is defined as clayey soU which has an expansion index of 50 or greater when tested in accordance with the American Society of Testing Materials (ASTM) Laboratory Test D4829-95. OVERSIZED MATERIAL: Oversized fUl material is generaUy defined herein as rocks or lumps of soU over six inches in diameter. Oversized materials should not be placed in fiU unless recommendations of placement of such material are provided by the Geotechnical Engineer. At least 40 percent of the fUl soUs shaU pass through a No. 4 U.S. Standard Sieve. TRANSITION LOTS: Where transitions between cut and fUl occur witiiin the proposed buUding pad, the cut portion should be undercut a minimum of one foot below the base of the proposed footings and recompacted as stmctaral backfUI. In certain cases that would be addressed in the geotechnical report, special footing reinforcement or a combination of special footing reinforcement and undercutting may be required.