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HomeMy WebLinkAboutCT 99-20; LOT 10 CARLSBAD AIRPORT CENTER; REPORT OF GEOTECHNICAL INVESTIGATION; 2000-08-22CHRISTIAN WHEELER ENGINEER-ING REPORT OF GEOTECHNICAL INVESTIGATION PROPOSED OFFICE PARK LOT 10 CARLSBAD AIRPORT CENTER OWENS AVENUE CARLSBAD, CALIFORNIA PREPARED FOR: BUIE IRISH VENTURES c/o SMITH CONSULTING ARCHITECTS 12220 EL CAMINO REAL, SUITE 200 SAN DIEGO, CALIFORNIA 92130 PREPARED BY: CHRISTIAN WHEELER ENGINEERING 4925 MERCURY STREET SAN DIEGO, CALIFORNIA 92111 4925 Mercury Street -f San Diego, CA 92111 ••• 858-496-9760 • FAX 858-496-9758 CHRISTIAN WHEELER ENGINEERING August 22, 2000 Buie Irish Ventures c/o Smith Consulting Architects 12220 El Camino Real, Suite 200 San Diego, California 92130 CWE 199.620.1R Attention: Scott Caims SUBJECT: REPORT OF GEOTECHNICAL INVESTIGATION, PROPOSED OFFICE PARK, LOT 10 CARLSBAD AIRPORT CENTER, OWENS AVENUE, CARLSBAD, CALIFORNIA. Ladies and Gendemen: In accordance with your request and our Proposal dated November 5,1999, we have completed a geotechnical investigation for the subject project. The findings and recommendations of our study are presented herewith. In general, the findings of this study indicate that the site is suitable for the proposed development. The most significant geotechnical condition that will affect the proposed site development consists of the presence of a pocket of highly expansive soil in the area of Lot No 5. It will be necessary to undercut the area where the expansive soils exists and replacing them with nondetrimentally expansive soil, which is readily available on the site. If you have any questions after reviewing the findings and recommendations contained in the attached report, please do not hesitate to contact this office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, CHRISTIAN WHEELER ENGINEERING, INC. Charles H. Christian, R.G.E. #00215 CHC:CRB:chc cc: (2) Submitted (4) Smith Consulting Architects Curtis R. Burdett, C.E.G. #1090 4925 Mercury Street • San Diego, CA 92111 • 858-496-9760 FAX 858-496-9758 TABLE OF CONTENTS PAGE Introduction and Project Description 1 Project Scope 2 Findings 3 Site Description 3 Site Development History 3 General Geology and Subsurface 4 Geologic Setting and Soil Description 4 Tectonic Setting 4 Geologic Hazards 5 General 5 Ground Shaking 5 Seismic Design Parameters 6 Liquefaction 6 Tsunamis 6 Seiches 6 Seismic Settlement and Differential Compaction 6 Ground Cracking and Surface Rupture 7 Slope Stability 7 Groundwater 7 Conclusion 7 General 7 Recommendations 8 Grading 8 Observation of Grading 8 Site Preparation 8 Surface Drainage 8 Earthwork 8 Foundations 9 General 9 Reinforcement 9 Settiement Characteristics 9 Expansive Characteristics 9 Foundation Plan Review 9 Foundation Excavation Observation 10 On-Grade Slabs 10 Interior On-Grade Floor Slabs 10 Exterior Slabs On-Grade 10 Earth Retaining WaUs 10 Passive Pressure 10 Active Pressure 11 Angle of Internal Friction/Unit Weight 11 Backfill 11 Preliminary Pavement Recommendations 11 Limitations 12 Field Explorations 13 Laboratory Testing 13 ATTACHMENTS FIGURES Figure 1 Site Vicinity IVIap, Follows Page PLATES Plate 1 Site Plan Plates 2-9 Boring Logs Plates 10-12 Test Trench Logs Plates 13 Laboratory Test Results Plate 14 R-Value Test Results Plate 15 Retaining Wall Subdrain Detail APPENDICES Appendix A References Appendix B Recommended Grading Specifications • General Provisions GEOTECHNICAL INVESTIGATION PROPOSED OFFICE PARJ< DEVELOPIvIENT LOT 10 CARLSBAD AIRPORT CENTER OWENS AVENUE CARLSBAD. CALIFORNIA INTRODUCTION AND PROJECT DESCRIPTION This report presents the results of our geotechnical investigation for a proposed office park development to be constructed on Lot 10 of Carlsbad Airport Center, in the Qty of Carlsbad, California. The location of the site, which is at the south end of Owen Avenue, is illustrated in the vicinity map presented on the following Figure Number 1. We understand that the subject property is to be divided into six parcels, five of which will be used to construct office buildings that will take up the entire parcel The sixth and largest parcel will include aU the parking and driveways areas, the landscape areas and the common areas between the parcels. The buildings will be two-story with tilt-up concrete construction, and are expected to have conventional shallow fovmdations and on-grade concrete floor slabs. The footprint of the buildings, which approximately coincide with the configuration of the parcels, will cover between about 6300 square feet to 9200 square feet. Asphalt concrete driveways and parking will be constructed on the north, east and west sides of the office building cluster. Precise grading to develop the property is expected to generally consist of cuts and fills of less than about five feet from existing grades. However, a retaining wall with a maximum height of about 15 feet is proposed in the parking area to create a larger parking area. To assist in the preparation of this report, we were provided with a tentative map prepared by JP Engineering, Inc., dated August 24,1999. A copy of this plan, which shows the site topography and the configurations of the parcels and parking and driveway areas, was used as the base for our Site Plan and is included herewith as Plate Number 1. In addition, we were provided with and have reviewed the foUowing document: PreUminary Geoteclmical Evaluation, Lots 1 and 10, Carlsbad Airport Center, Carlsbad, CaUfomia, by GeoSoils, Inc., dated Match 20,1998. Figure No. 1 C.W.E. 199.620.1R August 22,2000 Page 2 PROJECT SCOPE The investigation consisted of: surface reconnaissance, subsurface explorations, obtaining representative disturbed and undisturbed samples, laboratory testing, analysis of the field and laboratory data, research of avaUable geologic Uterature pertaining to the site, and preparation of this report. More specificaUy, the intent of this analysis was to: a) Explore the subsurface conditions to the depths influenced by the proposed construction. b) Evaluate, by laboratory tests, the pertinent engineering properties of the various strata which may influence the proposed construction, including bearing capacities, expansive characteristics, and setdement potential. c) Describe the general geology at the site including possible geologic hazards that could have an effect on the site development. d) Address potential construction difficulties that may be encountered due to soil conditions, groundwater, or geologic hazards, and provide preliminary recommendations concerning these problems. e) Develop soU engineering criteria for site preparation and grading, and address the StabiUty of the temporarj' cut slope for the proposed retaining waU. f) Provide preliminary asphalt concrete pavement and Portiand Cement concrete pavement design recommendations. g) Recommend an appropriate foundation system for the type of structures anticipated and develop soU engineering design criteria for the recommended foundation design. C.W.E. 199.620.1R August 22,2000 Page 3 FINDINGS SITE DESCRIPTION The subject property consists of a graded but undeveloped, irregular-shaped parcel of land. The vacant lot is located at the southwest terminus of Owens Avenue cul-de-sac and is identified as Lot 10 of Carlsbad Airport Center. The property is bounded on the north and east by developed research and development property, on the west by a natural canyon and on the south by Palomar Airport Road. A 200-foot-wide SDG & E utiUty easement runs along the north side of the lot and covers over half of the area of the lot. Overhead high voltage power lines exist in this easement, and a tower exists in the northwest corner of the lot A 15-foot-wide sewer easement and an adjacent 15- foot-wide storm drain easement also cross the easterly portion ofthe lot. TopographicaUy, the property consists of a large, relatively level, sheet-graded pad with a descending slope on the south side that extends down to Palomar Airport Road, and an ascending slope on the north that extends up to the adjacent properties. The slope that extends down to Palomar Airport Road is approximately 18 feet high and has an incUnation of 2:1, horizontal to vertical. The ascending slope on the north also has an incUnation of 2:1 or flatter, and has a maximum height of about 60 feet. An access road to the power Une tower extends up the north slope, dividing it into two separate slopes. The base of the tower is about 25 feet above the pad. Vegetation on the pad consists of a very sparse cover of natural grasses and weeds. The slopes have been planted with ground cover and appear to be routinely irrigated. SITE DEVELOPMENT HISTORY Prior to the development ofthe Carlsbad Airport Center subdivision, the subject property and siirrounding area was open undeveloped land or land used for agricultural purposes. A review of the pre-development 200-scale topographic maps indicates that the topography of the subject site proper was characterized by a moderately steep, southerly-facing hiUside that descended to a westerly- trending drainage channel. The original elevations ranged from approximately 165 feet in the area along Palomar Airport Road up to approxknately 260 feet near central area on the nortii site boundary. The mass grading for the tract was apparentiy performed under the testing and observation services of Moore & Taber in 1985 and 1986. We were unable to locate a copy of the report for the grading operations at the City of Carlsbad. C.W.E. 199.620.1R August 22,2000 Page 4 GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located near tiie boundary between the FoothiUs Physiographic Province and the Coastal Plains Physiographic Province of San Diego County and is underlain by Tertiary-age sedimentary deposits locaUy referred to as the Delmar Formation and minor amounts of artificial fUl material. The sedimentary deposits exposed by our test borings, for the most part, consisted of dense sandstone that is considered to be nondetrimentaUy expansive and have relatively high strength parameters. NondetrimentaUy expansive soU is defined herein as a sandy soil with an expansion index of less than 50. These soUs are classified by the Unified Soil Classification System as Silty Sands (SM) and Clayey Sands (SC). Interfingered with the sandstone material are lenses of very stiff to hard claystone. The claystone, which is classified as a sandy, silty day (CL), was encountered in Boring B-l at a depth of 4 to 9 feet below the existing grade, in Boring B-5 fi:om the ground surface to a depth of seven feet, and in Boring B-6 from 9 to over 15 feet below existing grade. The clays are considered to be highly expansive and have medium to relatively high strength parameters in their natural state. Please refer to the boring logs presented on the attached Plate Nos. 2 through 9 for more detailed information on the subsurface stratification below the graded pad. The existing cut slope where the retaining waU is proposed was logged at three locations. These logs are presented on Plate No. 10 through 12. The soils exposed at aU three log locations consisted of the dense to very dense sandstone unit of the Delmar Formation from the top to the bottom of the slope. The fiU material was only found in Borings B-7 and B-8 and was Umited in depth to approximately 12 inches. This material consisted of medium dense, moderately weU compacted, silty sand (SM). TECTONIC SETTING: Much of Southem CaUfornia, includbg San Diego County, is characterized by a series of Quaternary-age fault zones which typicaUy 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 witliin the zone) are classified as active whUe others are classified as only potentiaUy active according to the criteria of the CaUfornia Division of Mines and Geology. Active fault zones are those which have shown conclusive evidence of faulting during the Holocene Epoch (the most recent 11,000 years) whUe potentiaUy active fault zones have demonstrated C.W.E. 199.620.1R August 22, 2000 Page 5 movement during the Pleistocene Epoch (11,000 to 1.6 milUon years before the present) but no movement during Holocene time. A review of avaUable geologic maps indicates that the Rose Canyon Fault Zone is located approximately 6 mUes west of the site. Other active fault zones in the region that could possibly affect the site include the Coronado Bank and San Clemente Fault Zones to the west, the Elsinore and San Jacinto Fault Zones to the northeast, and the Agua Bianca and San Miguel Fault Zones to the south. Some minor inactive faults have been previously mapped in the general vicinity of the subject site; these smaU faults should be of only nominal consequence to the proposed project. GEOLOGIC HAZARDS GENERAL: The site is located in an area that is relatively free of significant geologic hazards. There are no hazards of sufficient magnitude to preclude development of the site as presendy proposed. GROUND SHAKING: A Ukely geologic hazard to affect the site is ground shaking as result of movement along one of the major active fault zones mentioned above. The maximum bedrock accelerations that would be attributed to a maximum magnitude earthquake occurring along the nearest fault segments of selected fault zones that could affect the site are summarized in fhe foUowing Table I. TABLE I Fault Zone Distance Maximum Probable Earthquake Maximum Bedrock Acceleration Rose Canyon 6 mUes 6.5 magnitude 0.30 g Coronado Bank 22 mUes 7.4 magnitude 0.16 g Elsinore 23 mUes 7.1 magnitude 0.14 g San Jacinto 47 miles 7.2 magnitude 0.07 g 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 likely tiiat the site will experience die effects of at least one moderate to large earthquake during the Ufe of die proposed structures. C.W.E. 199.620.1R August 22, 2000 Page 6 SEISMIC DESIGN PARAMETERS: Based on a maximum magnitude (Mmax) eartiiquake of 6.9 along the nearest portion of the Rose Canyon Fault Zone, the Maxunum Bedrock Acceleration at the site would be approximately 0.40 g. For stmctural design purposes, a damping ratio not greater tiian 5 percent of critical dampening, and Soil Profile Type Sc are recommended (UBC Table 16-J). Based upon the location oftiie site at approximately 9.5 kUometers from the Rose Canyon Fault Zone (Type B Fault), Near Source Factors Na equal to 1.0 and Nv equal to 1.02 are also appUcable. These values, along with other seismically related design parameters from the Uniform Building Code (UBQ 1997 edition. Volume II, Chapter 16, utUizing a Seismic Zone 4 are presented in tabular form bdow. TABLE II UBC-CHAPTER 16 SEISMIC RECOMMENDED TABLE No. PARAMETER VALUE 16-1 Sdsmic Zone Factor Z 0.40 16-1 SoU Profile Type Sc 16-Q Sdsmic Coeffident Ca 0.40 Na 16-R Sdsmic Coeffident Cv-0.56 Nv 16-S Near Source Factor Na 1.0 16-T Near Source Factor Nv 1.02 16-U Sdsmic Source Type B LIQUEFACTION: The materials at the site are not subject to Uquefaction due to such factors as soU density, grain-size distribution, and lack of shaUow groundwater. TSUNAMIS: Tsunamis are great sea waves produced by a submarine earthquake or volcanic emption. Due to the site's location, it is not subject to tsunamis. SEICHES: Seiches are periodic osciUations in large bodies of water such as lakes, harbors, bays, or reservoirs. No such large bodies of standing water are located in an area that could possibly affect the subject site. SEISMIC SETTLEMENT AND DIFFERENTIAL COMPACTION: The formational materials and the compacted fiUs at the site are aU medium dense/medium stiff to stiff and very stiff/very dense and are not subject to seismic settiement or differential compaction. C.W.E. 199.620.1R August 22,2000 Page 7 GROUND CRACKING AND SURFACE RUPTURE: No active faults are known to traverse the site, so the site is not considered subject to surface mpture from on-site faulting. Ground cracking caused by shaking from distant sdsmic sources is considered to be highly unlikely. SLOPE STABILITY: The site is identified as being in Relative LandsUde SusceptibiUty Area 3-1 accordkig to the LandsUde SusceptibUity Map prepared by the CaUfomia Division of Mines and Geology. Area 3 is considered to be a generaUy susceptible area and includes areas that are considered to be at or near their stabiUty limits due to a combination of weak materials and steep slopes. Based on our site-spedfic study and the information avaUable to date, it is our opinion that the likelihood of deep-seated slope instabiUty phenomena at the subject site proper can be considered to be low. Potential shaUow, surficial problems can be mitigated by the use of appropriate landscaping and slope maintenance practices. GROUNDWATER: We do not anticipate any major groundwater related problems, either during or after constmction. However, it should be recognized that minor groundwater seepage problems might occur after development of a site even where none were present before development. These are usuaUy minor phenomena and are often the result of an alteration of tiie permeabiUty characteristics of the soU, an alteration in drarnage pattems and an increase in irrigation water. Based on the proposed development scheme, it is our opinion that the likelihood of future seepage phenomena should be considered to be low. It is further our opinion fhat these problems can be most effectivdy corrected on an individual basis is and when they devdop. CONCLUSIONS GENERAL: In general, no geotechnical conditions were encountered which would preclude the development of the site as presentiy proposed provided the recommendations presented herein are foUowed. The geotechnical conditions encountered that wiU most affect the development of the site is the presence of moderately to highly expansive soUs in a portion of the buUding pads that wiU require removal and replacement with nondetrimentaUy expansive fill material within the zone of influence of the foundations and slab systems.. The fiU material was found to be moderately weU compacted. However, tiie upper foot of fiU material was found to have loosened over the years as a result of wetting and drying and the expansion characteristics of the soU. This material should be removed and replaced as uniformly compacted fiU. No otiier soU or geologic conditions were found that would significantiy affect die development of the property as proposed. C.W.E. 199.620. IR August 22, 2000 Page 8 RECOMMENDATIONS GRADING OBSERVATION OF GRADING: Continuous observation by Christian Wheder Engmeering is essential during the grading operation to constmct the bmlding pads and paved areas in order to confirm the conditions antidpated by our investigation, to aUow adjustments in design criteria to reflect the actual fidd conditions exposed, and to determine that the grading proceeds in general accordance with the recommendations contained herein. SITE PREPARATION: Site preparation should begin with the removal of any existkig vegetation and deleterious matter from the areas of the site to be graded and/or that wiU support new improvements. It is recommended that pocket of clayey soUs encountered in Boring B-5 be removed to a depth of at least four feet below finish pad grade and be replaced with nondetrimentaUy expansive fiU materiaL NondetrimentaUy expansive soU is defined herein as a sandy soU that has an expansion index of less than 50, as determined by UBC Test 29-2. The sandy soUs encountered through the site and in the proposed cut for the retaining waU wiU comply with this requkement. The mkiimum horizontal removal Umits of this operation should kiclude aU areas that wUl support settiement-sensitive improvements, includkig exterior walkways and paved areas. AU excavations should be approved by the geotechnical engineer or his representation prior to fUling. The soUs exposed at the bottom of aU excavations and in aU areas to recdve fiU material should be scarified to a depth of 12 inches, moisture-conditioned and be recompacted to at least 90 percent as determined ki accordance witii ASTM D-1557-91 prior to repladng the excavated fiU. AU fill should be placed in Ufts six to eight inches is thickness with each Uft mechanicaUy compacted to at least 90 percent of maximum dry density. SURFACE DRAINAGE: It is recommended tiiat aU surface drainage be dkected away from the stmcture and the top of slopes. Ponding of water should not be aUowed adjacent to foundations. EARTHWORK: AU eartiiwork and gradkig contemplated for site preparation should be accompUshed in accordance with the attached Recommended Grading Specifications and Spedal Provisions. AU spedal site preparation recommendations presented in the sections above wiU supersede tiiose ki the standard Recommended Grading Specifications. AU embankments, stmctural fiU and fiU should be compacted to at least 90 percent rdative compaction at or sUghtiy over C.W.E. 199.620.1R August 22,2000 Page 9 optimum moisture content. UtiUty trench backfiU within five feet of the proposed stmctures and beneath aU pavements should be compacted to a minimum of 90 percent of its maximum dry density. The upper twelve inches of subgrade beneath paved areas should be compacted to 90 percent of it maximum dry density. This compaction should be obtained by the paving contractor just prior to placing the aggregate base material and should not be part of the mass grading requkements. The maximum dry density of each soU type should be determined in accordance with ASTM Test D-1557-91. FOUNDATIONS GENERAL: ShaUow foundations may be utUized for the support of the proposed stmctures. AU footings should be embedded a minimum depth of 18 inches below lowest adjacent finish pad grade. A minimum width of 12 inches and 24 inches is recommended for continuous and isolated footings, respectively. A bearing capacity of 3,000 pounds per square foot may be assumed for said footings. This bearing capacity may be kicreased by one-thkd when considering wind and/or seismic forces. REINFORCEMENT: Footing reinforcement should be spedfied by the project stmctural engkieer. However, as a minknum we recommend that both exterior and interior continuous footings be reinforced with at least one No. 5 bar positioned near the bottom of the footkig and one No. 5 bar positioned near the top of the footkig. This reinforcement is based on soU characteristics and is not intended to be in Ueu of reinforcement necessary to satisfy stmctural considerations. SETTLEMENT CHARACTERISTICS: The antidpated total and/or differential settiements for the proposed stmcture wiU be less than one inch, provided the recommendations presented in this report are foUowed. It should be recognized that minor cracks normaUy occur in concrete slabs and foundations due to shrinkage during curing or redistribution of stresses and some cracks may be anticipated. Such cracks are not necessarUy an indication of excessive vertical movements. EXPANSIVE CHARACTERISTICS: The antidpated foundation soUs were found to vary from moderately expansive. The recommendations presented in this report reflect a highly expansive soU condition. FOUNDATION PLAN REVIEW: It is recommended tiiat die foundation plans be submitted to this office for review in order to verify that the recommendations presented in this report are incorporated in the stmctural plans. C.W.E. 199.620.1R August 22,2000 Page 10 FOUNDATION EXCAVATION OBSERVATION: We recommend tiiat aU footing excavations be observed by the geotechnical engineer to verify that the footkig excavations comply with our minknum recommendations and the stmctural plans, and that the soU conditions are as anticipated in the preparation of this report. ON-GRADE SLABS INTERIOR ON-GRADE FLOOR SLABS: The tiiickness, reinforcmg and compressive strengtii of the interior slabs should be spedfied by the stmctural engineer. However, as a minimum, we recommend that the interior concrete on-grade floor slabs have a acmal tiiickness of at least four inches. The interior concrete slabs should be reinforced witii at least No. 3 reinforcing bars placed at least at 18 kiches on-center each way. The floor slab reinforcing should be supported on chaks such that they wiU be positioned mid-height in the slab. Interior floor slabs should be underlain by a four-inch blanket of clean, poorly graded, coarse sand. The sand should have less than ten percent passing the #100 sieve and five percent passing the #200 sieve. Where moisture-sensitive floor coverings are planned, a visqueen barrier should be placed in the center of the sand layer. EXTERIOR SLABS ON-GRADE: Exterior slabs (excludkig driveways) should have a mkiimum thickness of four inches. WaUss or slabs five feet ki width should be rdnforced with at least No. 3 bars at 24 inches on center each way and provided with weakened plane joints. Any slabs between five and ten feet should be provided with longitudinal weakened plane jokits at the centerUnes. Slabs exceeding ten feet in width should be provided with a weakened plane jokit in accordance with American Concrete Instimte Standards. EARTH RETAINING WALLS PASSIVE PRESSURE: The passive pressure for the prevaUing soU conditions may be considered to be 400 pounds per square foot per foot of depth. This pressure may be increased one-thkd for seismic loadmg. The coeffident of fiiction for concrete to soU may be assimied to be 0.40 for the resistance to lateral movement. When combining frictional and passive resistance, the friction should be reduced by one-thkd. The upper 12 inches of exterior retainkig waU footings should not be kicluded in passive pressure calculations where abutted by landscaped areas. C.W.E. 199.620.1R August 22,2000 Page 11 ACTIVE PRESSURE: The active soU pressure for tiie design of unrestrained earth retaining stmctures with level backfiU may be assumed to be equivalent to tiie pressure of a fluid weighing 30 pounds per cubic foot An additional 13 pounds per cubic foot should be added to this value for retaining waUs that have a 2:1, horizontal to vertical, backslope. These pressures do not consider any other surcharge. If any are antidpated, this office should be contacted for the necessary increase in soU pressure. These values assume a drained baclvfiU condition. Waterproofing detaUs should be provided by the project architect A suggested waU subdrain detaU is provided on the attached Plate Number 15. We recommend that the Geotechnical Consultant be retained to observe aU retakiing waU subdrakis to verify proper constmction. ANGLE OF INTERNAL FRICTION/UNIT WEIGHT: For die design of segmental, reinforced earth retaining waUs, an angle of intemal friction of 35 degrees and a unit weight of 125pcf may be assumed. These values assume that the soUs used in the area ofthe reinforced earth consist of the on-site sandy soUs. In no event should the clayey soUs be used to backfiU in the reinforced earth area. BACKFILL: AU backfiU soUs shovild 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 vmtil the masonry has reached an adequate strength. PRELIMINARY PAVEMENT RECOMMENDATIONS The reconimended preUminary pavement sections presented on the foUowing page are based on a subgrade soU R-Value of 11, as determined from a representative sample ofthe antidpated subgrade soU by CaUfomia Test Method 301. In addition, since the use of the property wiU be as an office complex, which should have a relativdy low volume of tmck traffic, a traffic kidex of 5.5 and 4.5 was assumed for the design of the stmctural pavement section ki traffic areas such as driveways and trash tmck routes, and in areas strictiy Umited to automobUe parkUig, respectively. If heavy tmck traffic is expected, the pavement section recommendations presented below should be modified to reflect the antidpated traffic loads. The stmctural sections should be verified after "R" value tests of the acmal subgrade soUs are performed. AU paving methods and materials should conform with good engineering practices and with the requkements of the City of Carlsbad. C.W.E. 199.620.1R August 22,2000 Page 12 TRAFFIC AREAS 4.0 inches of asphalt concrete pavement, on 8.5 inches of cmshed aggregate base PARKING AREAS 4.0 inches of asphalt concrete pavement, on 6.0 inches of cmshed aggregate base The aggregate base material should conform with the Standard Spedfications for PubUc Works Constmction (Green Book), Section 200-2.2.2, and should be compacted to at least 95 percent relative compaction. The asphalt concrete should conform to Section 203-6.2.1 for the asphalt and Section 203-6.2.2 for the aggregate. The subgrade soils in the top 12 inches should be compacted to at least 95 percent relative compaction just prior to plackig base material. Therefore, this compaction shovild be accompUshed by the pavUig contractor. Portland Cement Concrete (PCC) pavement should have a minimum thickness of 5.5 inches and may be placed dkectiy on the native sandy soUs. The subgrade should be processed as recommended above for asphalt concrete sections. PCC should conform with Section 201 of the Green Book. The compaction of the subgrade and base material and the asphalt concrete lay down should be observed and tested by the geotechnical consultant. AU paving and constmction methods should comply widi good engineering practices, the Green Book and with the requkements of the City of Carlsbad. LIMITATIONS The recommendations and opinions expressed in this report reflect our best estimate of the project requkements based on an evaluation of the subsurface soU conditions encountered at die subsurface exploration locations and the assumption tiiat the soU conditions do not deviate appreciably from those encountered. It should be recognized diat the performance of the foundations may be influenced by undisclosed or unforeseen variations ki the soU conditions that may occur in the kitermediate 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 soUs engkieer so that he may make modifications if necessary. In addition, this office should be advised of any changes in C.W.E. 199.620.1R August 22,2000 Page 13 the project scope or proposed site grading so that it may be determined if the recommendations contained herdn are appropriate. This should be verified in writing or modified by a written addendum. FIELD EXPLORATIONS Eight subsurface explorations were made at the locations indicated on the attached Plate Number 1 on September 15,1999. These explorations consisted of borings made with a nine-inch-diameter, hoUow-stem auger driU rig. The fieldwork was conducted under the observation of our engineering geology personnd. The explorations were carefuUy logged when made. These logs are presented on the foUowing Plates Number 2 through 9. The soUs are described in accordance with the Uiufied SoUs Classification. In addition, a verbal textural description, the wet color, the apparent moisture and the density or consistency are provided. The density of granular soUs is given as dther very loose, loose, medium dense, dense or very dense. The consistency of sUts or clays is given as dther very soft, soft, medium stiff, stiff, very stiff, or hard. Disturbed and "undisturbed" samples of typical and representative soUs were obtakied and returned to the laboratory for testing. Representative undisturbed core samples were obtained by means of a SpUt tube sampler driven into the soUs by a 140-pound hammer free-faUing a distance of 30. The number of blows requked to drive the sampler the last twelve inches is indicated on the boring logs as "sample penetration resistance". LABORATORY TESTING Laboratory tests were performed ki accordance with the generaUy accepted American Society for Testing and Materials (ASTM) test metiiods or suggested procedures. A brief description of tiie tests performed is presented below: a) CLASSIFICATION: Field dassifications were verified in the laboratory by visual examination. The final soU classifications are in accordance with the Unified SoU Classification System. b) MOISTURE-DENSITY: In-place moisture contents and dry densities were determined for representative soU samples. This information was an aid to C.W.E. 199.620.1R August 22,2000 Page 14 classification and permitted recogrutioh of variations in material consistency witii depth. The dry unit wdght is determined in pounds per cubic foot, and the in-place moisture content is determined as a percentage of the soU's dry weight. The results are simimarized in the boring logs. c) GRAIN SIZE DISTRIBUTION: The gram size distribution was determkied for representative samples of native soUs in accordance with ASTM D422. The results of these tests are presented on Plate Number 13. d) EXPANSION INDEX TEST: Expansion kidex tests on remolded samples were performed on representative samples of soUs Hkdy to be present at finish grade. The tests were performed on the portion of the samples passing the #4 standard sieve. The samples were brought to optimum moisture content and then dried back to a constant moisture content for 12 hours at 230 +/- 9 degrees Fahrenheit The specimen were then compacted in a 4-inch-diameter mold in two equal layers by means of a tamper, then trimmed to a final height of 1 kich, and brought to a saturation of approximately 50 percent The specimen were placed in a consoUdometer with porous stones at the top and bottom, a total normal load of 12.63 pounds was placed (144.7 psf), and the sample was aUowed to consoUdate for a period of 10 minutes. The samples were aUowed to become saturated, and the change in vertical movement was recorded untU the rate of expansion became nominal. The expansion indexes are reported on the attached Plate Number 13 as the total vertical displacement time the fraction of the samples passing the #4 sieve times 1000. CLASSIFICATION OF EXPANSIVE SOIL EXPANSION INDEX POTENTIAL EXPANSION 1-20 very low 21-50 low 51-90 medium 91-130 high Above 131 very liigh e) DIRECT SHEAR TESTS: Dkect shear tests were performed to determme the faUure envelope based on yield shear strengtii. The shear box was designed to C.W.E. 199.620.1R August 22,2000 Page 15 accommodate a sample having a diameter of 2.375 inches or 2.50 inches and a hdght of 1.0 inch. Samples were tested at different vertical loads and a saturated moismre 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 the attached Plate Number 13. f) RESISTANCE VALUE TEST (R-VALUE): The Resistance value of a representative sample of the subgrade soU was determined ki accordance with CaUfomia Teat Method 301. The results of tiiis test are presented on Plate No. 14. LOG OF TEST BORING NUMBER B-l Date Excavated: 11/15/99 Logged by: DRR Equipment IR A300 Project Manager: CHC Surface Elevation: N/A •• Depth to Water N/A Hammer Weight 140 pounds Drop of Hammer: 30 inches SAMPLES O o s-O o W u ai DEPTH ( GRAPHIC I SUMMARY OF SUBSURFACE CONDITIONS SAMPLE TYl BULK PENETRATIC (blows/ ft. of dr MOISTURE ( DRY UNITWT LABORATO: TESTS si DEL MAR FORMATION fTd"*: YeUowish-brown to oUve. SA - 2 damp to moist, very dense, fine grained SILTY SAND (SM), abimdant iron staining. US 1 50/6" - 4 OUve, hard to very dense, SANDY SILTY CLAY/fine grained us 50/4" 17.4 107.8 EI - 6 i CLAYEY SAND (CL/SQ, abundant iron stains, sUght caliche. Expanison Index = 79 - 8 • - 10 Orangish-brown, moist, very dense, fine to medium grained us 50/3" 15.0 1029 - 10 CLAYEY SAND (SQ, abundant gypsum, rock concretion at 9 1/4 - 12 y$ feet - 14 -/ Grades to pinkish-brown in color. us 50/5V2 - 16 Bottom of boring at 15 feet - 18 -20 BUIE OFFICE PARK Owens Road, Carlsbad CHRISTl/y^ WHEELER BY: SD DATE: Nov-99 ENGINEER-ING JOB NO.: 199.620 PLATE NO.: 2 LOG OF TEST BORING NUMBER B-2 Date Excavated: 11/15/99 Logged by: DRR Equipment IR A300 Project Manager: CHC Surface Elevation: N/A Depth to Water: N/A Hammer Weight 140 pounds Drop of Hammer 30 inches SAMPLES GRAPHIC LOG DEPTH (ft) GRAPHIC LOG SUMMARY OF SUBSURFACE CONDITIONS SAMPLE TYPE D m PENETRATION (blows/ ft. of drive) MOISTURE (%) •& J—t 2 D >; Pi a LABORATORY TESTS DEL MAR FORMATION fTd"*: White to orangish-brown. II - 2 damp, very dense, fine to coarse grained SILTY SAND (SM), abundant kon stains. US 50/5" 17.2 107.7 DS - 4 'i US • 50/6" 123 1022 - 6 m - 8 Orangjsh-brown, moist, very dense, fine to coarse grained - 10 A • v"*l CLAYEY SAND (SQ, trace fine gravels. US 50/4" 15.0 1126 - 12 Grades to pinkish brown, sUg^t gypsum. - 14 us 50/6" - 16 Bottom of boring at 15 feet - 18 -20 CHRISTIAN WHEELER ENGINEER-ING BY: JOB NO. BUIE OFFICE PARK Owens Road, Carlsbad SD 199.620 DATE: PLATE NO.: Nov-99 LOG OF TEST BORING NUMBER B-3 Date Excavated: Equipment Surface Elevation: Hammer Weight 11/15/99 IRA300 N/A 140 pounds Lo^ed by: Project Manager Depth to Water Drop of Hammer DRR CHC N/A 30 inches fc Q O 2 u o SUMMARY OF SUBSURFACE CONDITIONS SAMPLES 2 % P. l4-l o fc ^ l-H O 2 Pi Q Pi « Id OH - 4 - 6 - 8 - 10 - 12 - 14 - 16 - 18 20 DEL MAR FORMATION (Td): White to gray, damp to moist, dense to very dense, fine to medium grained SILTY SAND (SM), abundant iron stains. US US 73 15.1 50/6" 108.3 Bottom of boring at 5 feet BUIE OFFICE PARK m Owens Road, Carlsbad CHRISTIAN WHEELER BY: SD DATE: Nov-99 ENGINEER-ING JOB NO.: 199.620 PLATE NO.: 4 LOG OF TEST BORING NUMBER B-4 Date Excavated: 11/15/99 Logged by: DRR Equipment IR A300 Project Manager CHC Surface Elevation: N/A Depth to Water N/A Hammer Weight 140 pounds Drop of Hammer 30 inches SAMPLES GRAPHIC LOG DEPTH (ft) GRAPHIC LOG SUMMARY OF SUBSURFACE CONDITIONS SAMPLE TYPE BULK PENETRATION (blows/ ft. of drive) MOISTURE (%) DRY UNIT WT.(pc LABORATORY TESTS DEL MAR FORMATION fTdl: White, damp, very dense. - 2 I fine to medium grained SILTY SAND (SM), abundant iron stains. US 50/5" 11.6 104.3 - 4 US 50/4" 15.4 106.8 - 6 - 8 us 50/6" 9.8 103.9' - 10 - 12 - 14 i I 1 bag 50/2" - 16 Bottom of boring at 15 feet - 18 -20 BUIE OFFICE PARK Owens Road, Carlsbad CHRISTIAN WHEaER BY: SD DATE: Nov-99 ENGINEER-ING JOB NO.: 199.620 PLATE NO.: 5 LOG OF TEST BORING NUMBER B-5 Date Excavated: Equipment Surface Elevation: Hammer Weight 11/15/99 IRA300 N/A 140 pounds Logged by: Project Manager Depth to Water Drop of Hammer DRR CHC N/A 30 inches SAMPLES SUMMARY OF SUBSURFACE CONDITIONS O 3 l—l 'V o d z ^ W o fc ^ o 2 Pi - 4 - 8 - 10 - 12 - 14 - 16 18 DEL MAR FORMATION (Td): light brown to gray, moist, hard, SANDY SILTY CLAY and daystone (CL), sUgJit iron staining. Expansion Index = 111 US US 78 19.5 1023 50/6" 20.9 1024 White to light orangish-brown, moist, very dense, fine to medium grained SILTY SAND (SM). US 50/5' 10.2 106.7 US 50/4" EI SA DS Bottom of boring at 15V2 feet BUIE OFFICE PARK Owens Road, Carlsbad CHRISTIAN WHEELER BY: SD DATE: Nov-99 ENGINEER-ING JOB NO.: 199.620 PLATE NO.: 6 LOG OF TEST BORING NUMBER B-6 Date Excavated: Equipment Surface Elevation: Hammer Weight 11/15/99 IRA300 N/A 140 pounds Lo^ed by: Project Manager Depth to Water Drop of Hammer DRR CHC N/A 30 inches fc W Q 2 o ffi fc SAMPLES SUMMARY OF SUBSURFACE CONDITIONS CO > ^ ° W .2 fc 3 fe O o t-H 2 D P CO OP - 4 - 6 - 8 - 10 - 12 - 14 - 16 18 1-20 DEL MAR FORMATION (TdV. White to orangish-brown, moist, very dense, fine to medium grained SILTY SAND (SM), very abundant iron stains. US 67 16.1 107.6 DS US 50/4'/! 17.5 111.7 OUve, moist, hard, SANDY SILTY CLAY and daystone (CL), abundant iron stains. Becomes medium brown. US 50/6' 23.8 100.7 US 50/4" Bottom of boring at 15 feet BUIE OFFICE PARK Owens Road, Carlsbad CHRISTIAN WHEELER BY: SD DATE: Nov-99 ENG1NEER.ING JOB NO.: 199.620 PLATE NO.: 7 LOG OF TEST BORING NUMBER B-7 Date Excavated: Equipment Surface Elevation: Hammer Weight 11/15/99 IRA300 N/A 140 pounds Logged by: Project Manager Depth to Water Drop of Hammer DRR CHC N/A 30 inches X H fc W P o l-J U S fc o SAMPLES SUMMARY OF SUBSURFACE CONDITIONS fe )—i O 2 2 P Pi 0, O^ - 2 i - 6 - 8 FIfT.T. (Qaf>; light brown, damp, medium dense, fine to medium grained SILTY SAND (SM), sUg^t claystone fragments, DEL MAR FORMATION (Tdy. White to Ught brown, moist to damp, medium dense to dense, fine to medium grained, CLAYEY SILTY SAND (SC/SM), abundant kon stains. Becomes very dense at 3 feet Bottom of boring at 5 feet US us 44 50/6" 14.6 10 - 12 - 14 - 16 - 18 1-20 RV 105.4 BUIE OFFICE PARK Owens Road, Carlsbad CHRISTIAN WHEELER BY: SD DATE: Nov-99 ENGlNEER-lNG JOB NO.: 199.620 PLATE NO.: 8 LOG OF TEST BORING NUMBER B-8 Date Excavated: Equipment Surface Elevation: Hammer Weight 11/15/99 IRA300 N/A 140 pounds Lo^ed by; Project Manager Depth to Water Drop of Hammer DRR CHC N/A 30 inches fc W P O O u X fc SUMMARY OF SUBSURFACE CONDITIONS SAMPLES ta 00 -4 fc D fe O u E-l 2 Pi p Pi Qp - 4 - 6 FTT.T. (Qaf); lig^t brown, damp, medium dense, fine to medium grained SILTY SAND (SM), trace gravels. DEL MAR FORMATION CTdY. White, moist, very dense, fine to medium grained SILTY SAND (SM), abundant iron stains. US us 50/6" 50/4% 11.3 108.1 10 - 12 14 - 16 - 18 1-20 Bottom of boring at 5 feet CHRISTIAN WHEELER ENGINEERING BUIE OFFICE PARK Owens Road, Carlsbad BY: SD JOB NO. 199.620 DATE: Nov-99 PLATE NO.: LOG OF TEST TRENCH NUMBER T-l Date Excavated: Equipment Surface Elevation: Hammer Weight 11/15/99 Manual N/A N/A Logged by: DRR Project Manager CHC Depdi to Water N/A Drop of Hammer N/A fc W P o o l-I U l-H X Pi o SAMPLES SUMMARY OF SUBSURFACE CONDITIONS 00 fc ^ fe l-H o u E- l-H 2 Pi P Pi gfe O^ CO < - 4 -10 - 12 20 -22 24 1-26 DEL MAR FORMATION (Td;): White, damp to moist, dense to very dense, fine to medium grained SILTY SAND (SM). Test trench ended at 24 feet BUIE OFFICE PARK Owens Road, Carlsbad vn Ml CHRISTIAN WHEELER BY: SD DATE: Nov-99 ENGINEER-ING JOB NO.: 199.620 PLATE NO.: 10 LOG OF TEST TRENCH NUMBER T-2 Date Excavated: Equipment Surface Elevation: Hammer Weight 11/15/99 Manual N/A N/A Lo^ed by: DRR Project Manager CHC Depth to Water N/A Drop of Hammer N/A fc W P o O IJ U l-H X o SAMPLES SUMMARY OF SUBSURFACE CONDITIONS Z 13 fe l-H O o 2 P °fe I oo OH - 2 - 4 - 6 10 12 26 -28 30 1-32 ^^^^ DEL MAR FORMATION rTd^: White, damp to moist, dense to very dense, fine to medium grained SILTY SAND (SM). Test trench ended at 30 feet CHRISTIAN WHEELER ENGINEERING BUIE OFFICE PARK Owens Road, Carlsbad BY: SD JOB NO.: 199.620 DATE: Nov-99 PLATE NO.: 11 LOG OF TEST TRENCH NUMBER T-3 Date Excavated: Equipment Surface Elevation: Hammer Weight 11/15/99 Manual N/A N/A Lo^ed by: DRR Project Manager CHC Depth to Water N/A Drop of Hammer: N/A O O U l-H X fc o SAMPLES SUMMARY OF SUBSURFACE CONDITIONS 00 Z ^ z & fc g. 3 fe l-H O u 2 Pi P b Pi 00 ol" - 2 - 4 - 6 - 8 - 10 - 12 24 -26 -28 30 DEL MAR FORMATION CTdy. White, damp to moist, dense to very dense, fine to medium grained SILTY SAND (SM). Test trench ended at 28 feet CHRISTIAN WHEaER ENGINEER-ING BUIE OFFICE PARK Owens Road, Carlsbad BY: SD JOB NO. 199.620 DATE: Nov-99 PLATE NO.: 12 LABORATORY TEST RESULTS LOT 10, CARLSBAD AIRPORT CENTER DIRECT SHEAR TEST Sample Number Condition Angle of Friction Apparent Cohesion EXPANSION INDEX TEST Sample Number Initial Moisture Content Initial Dry Density Finial Moisture Content Expansion Index Classification Boring B-2 2' Remolded to 90 % 37 Degrees 150 PSF Boring B-5 @ 2' Remolded to 90 % 18 Degrees 550 PSF Boring B-6 @ @' Remolded to 90 % 35 Degrees 150 PSF Boring B-l @ 4'-8' 12.5 Percent 98.9 PSF 29.8 Percent 79 Moderate Boruig B-5 @ 0'-5' 13.8 Percent 98.8 PSF 34.0 Percent 111 High GRAIN SIZE DISTRIBUTION Sample Number Sieve Size #4 #8 #15 #30 #50 #100 #200 0.05 mm 0.01 mm 0.001 mm Borkig B-l @ 0 '- 4' Percent Passing Bo.ringB-5@0'-5' Percent Passing 100 100 99 99 96 " 98 91 96 85 95 69 91 47 84 75 54 30 CWE 199.620.1 December 8,1999 Plate No. 13 SAMPLE: R-l. B-7 @ 0-4' TEST SPECIMEN A B C D E DATE TESTED 2-Dec 2-Dec 2-Dec Compactor Air Pressure psi 110 225 350 Initial Moisture % — -— Moistare at Compaction % 15.3 12.7 11.8 Briquette Height in. 2.66 2.5 2.57 Density pcf 114.0 121.3 120.2 EXUDATION PRESSURE psi 259 518 748 FXPANSION PRESSURE DIAL 0.0035 0.0049 0.0077 Ph at 1000 pounds psi ~ -- Ph at 2000 pounds psi 133 110 103 Displacement tarns 5.47 4.65 4.08 "R" Value 8 20 25 CORRECTED "R" VALUE 9 20 26 "R" Value at 300 psi Exudation Pressure = 11 "R" Value by Expansion = 8 GRAIN SIZE DISTRIBUTION SIEVE AS RECEIVED AS TESTED 3 21/2 2 1 1/2 3/4 1/2 3/8 #4 #8 #16 #30 #50 #100 #200 0.05mm 0.005mm 0.001mm LIQUID LIMIT PLASTIC LIMIT PLASTICITY INDEX SAND EQUIVALENT 800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 EXUDATION PRESSURE psi CHRISTIAN WHEELER ENGINEER-ING BY: SCC JOB NO.: 199.620 DATE: Aug-00 PLATE: 14 WATERPROOF BACK OF WALL PER ARCHITECT'S SPECfFICATIONS 3/4 INCH CRUSHED ROCK or MIRADRAIN 6000 or EQUIVALENT GEOFABRIC BETWEEN ROCK AND SOIL TOP OF GROUND or CONCRETE SLAB MINIMUM 4 INCH DWMETER PERFORATED PIPE RETAINING WALL SUBDRAIN DETAIL No Scale Christian Wheeler Engineering Job Number: 199.620.1R Date: AUGUST 2000 Plate Number: 15 CWE 199.620 August 22, 2000 Appendix A, Page Al REFERENCES Anderson, J.G.; Rockwell, R.K. and Agnew, D.C, 1989, Past and Possible Future Eartiiquakes of Significance to the San Diego Region, Earthquake Spectra. Volume 5, No. 2,1989. CaUfomia Division of Mines and Geology, 1998, Maps of Known Active Fault Near Source-Zones in CaUfomia and Adjacent Portions of Nevada. Jennkigs, C.W., 1975, Fault Map of CaUfomia, CaUforrua Division of Mines and Geology, Map No. 1; Scale 1:750,000 Kem, P., 1989, Earthquakes and Faults in San Diego County, Pickle Press, 73 pp. Mualchin, L. and Jones, A.L., 1992, Peak Acceleration from Maximum Credible Eartihquakes in CaUfomia (Rock and Stiff-SoU Sites) CaUfomia Division of Mmes and Geology Open-FUe Report 92-1. Tan, S. S. and Giffen, D. G., 1995, LandsUde Hazards ki die Nortiiem Part oftiie San Diego MetropoUtan Area, San Diego County, CaUfomia; CaUfomia Division of Mines and Geology, Open-FUe Report 95-04. U. S. Department of Agriculture, 1970, SoU Survey, San Diego County. U. S. Federal Emergenq' Management Agency, 1997, Countywide Flood Insurance Rate Map. Wesnousky, S.G., 1986, "Earthquakes, Quatemary Faults, and Seismic Hazards in CaUfornia," in Journal of Geophysical Research, Vol. 91, No. B12, pp 12,587 to 12, 631, November 1986. TOPOGRAPHIC MAPS County of San Diego, 1978, Map Sheet 350-1683; Scale: 1 kich = 200 feet U.S. Geological Survey, 1967, 7 Va MUiute Topographic Maps, Oceanside Quadrangle. U.S. Geological Survey, 1975, 7 Vi Minute Topographic Maps, Oceanside Quadrangle. CWE 199.620.1R August 22, 2000 Appendix B, Page Bl RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS PROPOSED OFFICE PARK LOT 10. CALRLSBAD AIRPORT CENTER OWENS AVENUE CARLSBAD. CALIFORNIA GENERAL INTENT The intent of these specifications is to estabUsh procedures for clearing, compacting natural ground, preparing areas to be fiUed, and placing and compactUig fiU soUs to die lines and grades shown on the accepted plans. The recommendations contained in the preliminary 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 confUct These specifications shaU only be used in conjunction with the geotechrtical report for which they are a part. No deviation from these specifications wiU be aUowed, except where specified in the geotechnical report or in other written communication signed by the Geotechiucal Engkieer. OBSERVATION AND TESTING Christian Wheeler Engineering shaU be retained as the Geotechnical Engineer to observe and test the earthwork in accordance with these specifications. It wiU be necessary that the Geotechrtical 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 the responsibiUty of the contractor to assist the Geotechiucal Engkieer and to keep him 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 preliminary geotechnical report are encountered during the grading operations, the Geotechnical Engineer shaU be contacted for further recommendations. If, in the opinion of the Geotechnical Engineer, substandard conditions are encountered, such as questionable or unsuitable soU, unacceptable moisture content, inadequate compaction, adverse weather, etc., construction should be stopped until the conditions are remedied or corrected or he shaU recommend rejection of this work. CWE 199.620.1R August 22, 2000 Appendix B, Page B2 Tests used to detennine die degree of compaction should be performed in accordance with the foUowing American Society for Testkig and Materials test methods: Maximum Density & Optimum Moisture Content - ASTM D-1557-91 Density of SoU In-Place - ASTM D-1556-90 or ASTM D-2922 AU densities shaU 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. AU areas disturbed by site grading should be left in a neat and finished appearance, free from unsightiy debris. After clearing or benching the natural ground, the areas to be fiUed shaU be scarified to a depth of 12 inches, brought to the proper moisture content, compacted and tested for the specified minimum degree of compaction. AU loose soUs in excess of 6 inches thick should be removed to fkm natural ground which is defined as natural soU which possesses an in-sim density of at least 90 percent of its maximum dry density. When the slope of the natural 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 firm competent formational soU. The lower bench shaU be at least 10 feet wide or V/2 times the equipment width, whichever is greater, and shaU be sloped back into the hiUside at a gradient of not less than two (2) percent AU otiier benches should be at least 6 feet wide. The horizontal portion of each bench shaU be compacted prior to receiving fUl as specified herein for compacted natural ground. Ground slopes flatter than 20 percent shaU be benched when considered necessary by the Geotechnical Engineer. Any abandoned buried stmctures encountered during grading operations must be totally removed. AU underground utiUties to be abandoned beneath any proposed stmcture should be removed from withki 10 feet of the stmcture and properly capped off The resulting depressions from the above described procedure should be backfiUed witii acceptable soU that is compacted to the requkements of the Geotechnical Engineer. This includes, but is not limited to, septic tanks, fuel tanks, sewer CWE 199.620.1R August 22, 2000 Appendix B, Page B3 lines or leach Unes, storm drains and water lines. Any buried stmctures 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. FILL MATERIAL Materials to be placed in the fiU shaU be approved by the Geotechnical Engineer and shaU be free of organic matter and other deleterious substances. Granular soU shaU contain sufficient fine material to fiU the voids. The definition and disposition of oversized rocks and expansive or detrimental soUs are covered in the geotechnical report or Special Provisions. Expansive soUs, soUs 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 Engkieer. Any import material shaU be approved by the Geotechnical Engineer before being brought to the site. PLACING AND COMPACTION OF FILL Approved fUl material shaU be placed in areas prepared to receive fiU in layers not to exceed 6 kiches in compacted thickness. Each layer shaU have a uniform moisture content in the range that wiU aUow 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 economicaUy compact the layer. Compaction equipment should either be SpecificaUy designed for soU compaction or of proven reUabiUty. 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. When the structural fiU material includes rock, no rocks wiU be aUowed to nest and aU voids must be carefioUy fiUed with soU such that the minimum degree of compaction recommended in the Special Provisions is acliieved. The maxunum size and spacing of rock permitted in stmctural fiUs and in non-stmctural fiUs is discussed in the geotechnical report, when appUcable. Field observation and compaction tests to estimate the degree of compaction of the fiU wUl be taken by the Geotechnical Engkieer or his representative. The location and frequency ofthe tests shaU be at the Geotechnical Engineer's discretion. Wlien the compaction test indicates that a particular layer is at less than the requked degree of compaction, the layer shaU be reworked to the satisfaction of the Geotechnical engineer and until the desired relative compaction has been obtained. CWE 199.620.1R August 22, 2000 Appendix B, Page B4 FiU slopes shaU be compacted by means of sheepsfoot roUers or other suitable equipment. Compaction by sheepsfoot roUer shaU be at vertical intervals of not greater than four feet In addition, fiU slopes at a ratio of two horizontal to one vertical or flatter, should be trackroUed. Steeper fiU slopes shaU be over-buUt and cut-back to firush contours after the slope has been constructed. Slope compaction operations shaU result in aU fiU 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. TTie compaction operation on the slopes shaU be continued until the Geotechnical engineer is of the opinion that the slopes wiU be surficiaUy stable. Density tests in the slopes wiU be made by the Geotechnical Engkieer during construction of the slopes to determine if the requked compaction is being achieved. Where failing tests occur or other field problems arise, the Contractor wiU be notified that day of such conditions by written communication from the Geotechnical Engineer or his representative in the form of a daUy field report. If the method of achieving the requked slope compaction selected by the Contractor faUs to produce the necessary results, the Contractor shaU rework or rebuUd such slopes untU the requked degree of compaction is obtakied, at no cost to the Owner or Geotechnical Engineer. CUT SLOPES The Engkieering 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 preliminary report such as perched water, seepage, lenticular or confined strata of a potentiaUy adverse nature, unfavorably inclined bedding, joints or fault planes are encountered during grading, these conditions shaU be analyzed by the Engineering Geologist and Geotechnical Engineer to determine if mitigation measures are necessary. Unless otherwise specified ki the geotechnical report, no cut slopes shaU be excavated higher or steeper than that aUowed by the ordinances of the controlling governmental agency. CWE 199.620.1R August 22, 2000 Appendix B, Page B5 ENGINEERING OBSERVATION Field observation by the Geotechnical Engineei: or his representative sliaU be made during the filling 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 the observation and testing shall release the Grading Contractor from his duty to compact aU fiU material to the specified degree of compaction. SEASON UMITS FUl shaU not be placed during unfavorable weatiier conditions. When work is intermpted by heavy rain, fiUing operations shaU not be resumed until the proper moisture content and density of the fiU materials can be achieved. Damaged site conditions resulting from weather or acts of God shaU be repaked before acceptance of work. RECOMMENDED GRADING SPECIFICATIONS - SPECIAL PROVISIONS RELATIVE COMPACTION: The mkiimum degree of compaction to be obtained in compacted natural ground, compacted fiU, and compacted backfiU shaU be at least 90 percent. For street and parking lot subgrade, the upper six 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 Uniform BuUdkig Code Standard 29-C. OVERSIZED MATERIAL: Oversized fiU material is generaUy defined herein as rocks or lumps of soU over 6 inches Ui 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 fiU soUs shaU pass through a No. 4 U.S. Standard Sieve. TRANSITION LOTS: Where ttansitions between cut and fUl occur witiiin tiie proposed buUding pad, the cut portion should be undercut a minimum of 18 inches below the base of the proposed footings and recompacted as stmctural backfiU. In certaki cases that would be addressed in the geotechnical report, special footkig reinforcement or a combination of spedal footkig reinforcement and undercutting may be requked.