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Home My WebLink About; 2910 Jefferson St Office Bldg; Soils Report; 1980-12-17-. - GEOTECHNICAL IWESTIBATION PROPOSEB OFFICE BUILOM SITE 2910 JEFFERSON STREET CARLSBAO. CALIFORNIA PREPARED FOR: Blankenshlp Developmnt Company, Inc. Post Office Box 1307 Carlsbad, California PREPARED BY: Southern California Soil 6 Testing. Inc. 6280 Riverdale Street San Diego, California ENGINEERING DEPT. LIBRARY City of Carlsbad 2075 Las Palmas Drive CarlsbarkCA 92009-4859 I December 17, 1980 Blankenship Development Company, Inc. Post Office Box 1307 Carlsbad. California 92008 SCSET I3789 Report No. 1 SUBJECT: Report of Geotechnical Investigation for the Proposed Office Building Site, 2910 Jefferson Street, Carlsbad, California. Gentlemen: In accordance with your request we have completed a geotechnical investi- gation for the proposed project. We are presenting herewith our findings and recomnendations. The findings of this study indicate that the site is suitable for the proposed development provided the recommendations presented in the attach- ed report are complied with. If you have any questions after reviewing the findings and recomnendations contained in the attached report, please do not hesitate to contact this office. SOUTHERN CALIFORNIA s 0 I L AND TE*sTING. I N c SCSBT 13789 December 17, 1980 Page 2 This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, SOUTHERN CALIFORNIA SOIL 8 TESTING, INC. elfast.l/project Engineer l5?-4f?ba Curtis R. Burdett, R.G. #3595 g$-&&-& Charles H. Christian, R.C.E. 22330 CHC:CRB:AFB:nw cc: (5) Submitted (1) Krommenhoek & McKeown & Assoc. (1) SCSAT, Escondido \,..~ ” Introduction and P ‘r Project Scope..... . PAGE eject Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Findings .............................................................. 2 Site Topography and Surface Description ........................... 2 General Geology and Subsurface Conditions ...................... ...3 . Geologic and Tectonic Setting .............................. 3 Soil Description ........................................... 3 Groundwater ................................................ 4 Geologic Hazards .................................................. 4 Recommendations and Conclusions ....................................... 4 TABLE OF CONTENTS General ........................................................... 4 Site Preparation ........................................... . ...... 5 .............................................. 5 Demolition... Soil Preparat Earthwork.... Foundations......... .ion ........................................... 5 .............................................. 5 .............................................. 6 General .................................................... 6 Lateral Resistance ......................................... 7 Settlement Characteristics ................................. 7 Expansive Characteristics .................................. 7 Pavement Recomnedations ........................................... 7 Limitations ........................................................... 8 Review, Observation and Testing ................................... 8 Uniformity of Conditions .......................................... 8 Change in Scope ................................................... 9 Time Limitations .................................................. 9 Warranty .......................................................... 9 Client's Responsibility .......................................... 10 Field Explorations ................................................... 10 Laboratory Testing ................................................... 11 ATTACHMENTS f 1 FIGURES FOLLOW PLATE Figure 1 Vicinity Map ............................................... 1 Figure 2 Regional Fault Map ......................................... 3 PLATES Plate 1 Site Configuration, Subsurface Locations Plate 2-3 Trench Logs Plate 4 Unified Soil Classification Chart Plate 5 Direct Shear Test Results Maximum Density and Optimum Moisture Content Piate 6 Grain Size Distribution APPENDIX Recommended Grading Specifications and Special Provisions f GEOTECHNICAL IWVESTISATION PROPOSED OFFICE BUILDING SITE 2910 JEFFERSON STREET CARLSBAD, CALIFORNIA INTRODUCTION Aw PROJECT DESCRIPTION This report presents the results of our geotechnical investigation for the proposed office building site which is to be located at 2910 Jefferson Street in Carlsbad, California. It is our understanding a two-story, wood-frame 'structure will be con- structed over a parking facility to be built approximately 2 feet below grade. It is further understood that due to the level nature of the site, a minimal amount of grading is anticipated. For our investigation, we were provided with a site plan prepared by Kromnenhoek, McKeown and Associates, A.I.A. The site location is shown on the vicinity map provided on the following Figure 1. The site configura- tion, and location of our subsurface explorations are provided on Plate Number 1. PROJECT SCOPE This investigation consisted of: surface reconnaissance; subsurface explorations; obtaining representative disturbed and undisturbed samples; laboratory testing; analysis of the field and laboratory data; research of available geological literature pertaining to the site; and preparation of this report. Specifically, the intent of this study is to: 4 Explore the subsurface conditions to the depths influenced by the proposed construction. .i ._ -- -- -- --i.-- -_ i. i / I I I I - i- I I ---A - _ _ _.__ +--.. _ . ..__. .’ I REG,E/VCE a- 7iYOUAS 0QOS. /4F3 BOUTI-I~RN CALfFORNIA Blankenship Office Building BOIL L TE~TINQ, INC. 2910 Jefferson . ..a "IY."O.L. .T".rnT ..N OI.0eB. Cm.lCO"NlA ..,.D Carlsbad, California av CRB MTE 12-17-80 a ~0. 13789 ' /Figure No. 1 XX&T 13769 December 17, 1980 Page 3 GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC AND TECTONIC SEllIRG: The subject site is located in the Coastal Plains Physiographic Province of San Diego County and is underlain by Duaternary beach terrace deposits. The terrace deposits typically consist of a weakly to moderately cemented sandstone. No evidence of on-site faulting was apparent during our subsurface explor- ations or a surface reconnaissance, and a review of available geologic maps indicates that no faults traverse the vicinity of the subject site. However, it should be recognized that Southern California is generally a seismically active area characterized by major. active fault zones that could possibly affect the subject site. The nearest of these is the Eisinore Fault Zone, located approximately 24 miles to the northeast, and the San Jacinto Fault zone, located approximately 46 miles to the north- east. In addition, the northern extension of the Rose Canyon Fault Zone is located approximately 5 miles to the west. The Rose Canyon Fault Zone is currently classified as potentially active rather .than active. This classification is based on a lack of conclusive evidence to verify Holo- cene (most recent 11.000 years) movement along the fault zone. A map showing the location of the major faults in the region is provided as Figure 2. SOIL DESCRIPTION: Specific soil conditions, as encountered in our sub- surface explorations, were from approximately 1 to 1 l/2 feet of loose to medium dense topsoils consisting of brown, humid to moist, silty sands which grade into the beach terrace deposits. These deposits were found to consist of red-brown, moist, dense, silty sands which were weakly to moderately cemented. I. SOUTHERN c A L- FORNIA BDlL Al-40 ,-LSTIHO. I N c. - - - - - - - - - - GRAPHIC SCALE - MILES from: California Division of Mines and Geology 'Fault Mal;;~gCalifornla'~ 8OUTHERN CALIFORNIA Office Building Site BOIL 6 TESTINQ, INC. 2910 Jefferson Street . ..a "I".IDAL. .T"..1 .AN 01.00. OALICOLINIA ..,rnD Carlsbad, California By AFB ONE 12-18-80 Regional Fault Map -ilOB NO. 13789 * Finure No. 2 SCS&T 13789 December 17. 1980 Page 4 GROWLWATER: The groundwater table was not encountered in our subsurface explorations, and no groundwater related problems are anticipated either during or after construction. GEOLOGIC HAURDS The subject site is located in an area which is relatively free of potent- ial geologic hazards. The most likely geologic hazard to affect the site is groundshaking as a result of movement along the major, active fault zones mentioned above. Based on a maximum probable. earthquake of 7.3 magnitude along the Elsinore Fault Zone, or a maximum probable earthquake of 7.8 along the San Jacinto Fault Zone, the maximum ground acceleration at the site could be as high as 0.21 g. There is also a remote possi-, bi-lity that movement could occur along the Rose Canyon Fault Zone during the life of the proposed structure. Based on a maximum probable earth- quake of 6.0 magnitude along the Rose Canyon Fault, maximum ground accel- eration at the site could be on the order of 0.38 g. However, in view of the current classification of the Rose Canyon Fault Zone, we are of the opinion that it should not be used as'the "design earthquake" fault for structures such as that proposed for the subject development. Construc- tion in accordance with the minimum standards of the most recent edition of the Uniform Building Code should minimize potential damage due to seismic activity. Other potential geologic hazards 'such as tsunamis, seiches, liquefaction. or landsliding should be considered negligible or nonexistent. RECOmENDATIOHS AM) CONCLUSIOWS GENERAL Based on the findings of this study, we conclude that with respect to geo- technical aspects, the subject site is suitable for the proposed project provided the recomnendations contained in this report are fully complied with. SCS&T 13789 December 17, 1980 Page 5 SITE PREPFRATIOW DEttOLITION: As previously described, the subject site contains existing structures which are to be demolished. During demolition operations, all construction debris and deleterious materials should be disposed of off- site. Any existing utilities that will not be utilized should be removed, properly capped off, and these excavations backfilled with uniformly compacted soil. The removal of trees should include the removal of their rootballs and depressions resulting from their removal should be back- filled with uniformly compacted soils. SOIL PREPARATION: In view of the plan to construct the parking level 2 feet below grade, and because the in-situ soils at~this depth appear to be of a competent nature, no special site preparations are considered neces- sary, other than the normal scarification and compaction of the surface soils. However, should any loose soils be encountered at the bottom of the footing excavations, they should be removed and the footings extended into firm natural ground. Further, we recommend that the footing excava- tions be inspected by a representative of our firm prior to placing con- crete. * EARTIUORK: All earthwork and grading contemplated ,for site preparation should 'be accomplished in accordance with the attached Recomnended Grading Specifications and Special Provisions. All special site preparation recormrendations presented in the sections above will supersede those in the standard Recommended Grading Specifications. All embankments, struct- ural fill, and fill should be compacted to a minimum of 90%. Utility trench backfill within 5 feet of the proposed structures and beneath asphalt or concrete pavements should be compacted to a minimum of 90% of its maximum dry density. The maximum dry density of each soil type should be determined in accordance with A.S.T.M. Test Method 1557-70, Method A or C. SCShT 13789 December 17, 1980 Page 6 FDUNDATIDNS GENEBM: Conventional spread footings, founded in the firm in-situ soils may be used to support the proposed structure. Conventional spread foot- ings should be founded a minimum of 18 inches below lowest adjacent finish grade and have a minimum width of 15 inches for continuous footings, and 24 inches for isolated footings. Continuous spread footings of minimum dimensions may be designed for an allowable soil bearing pressure of 3000 pounds per square foot. The allowable bearing pressure for footings of other dimensions is expressed by the following equations. Continuous Footings: q = 1.30 + 0.800 + 0.408 Square Footings: 9 - 1.56 + 0,800 + 0.328. ' . Circular Footings: q = 1.56 + 0.800 t 0.24B Where: q = Allowable soil bearing pressure as limited in shear in kips per square foot for full live and dead loads. D = Footing depth below adjacent grade in feet. B = Footing width or diameter in feet. The maximum soil bearing pressure calculated from the above expressions should be limited to 4,000 pounds per square foot. These stresses may be increased by one-third for wind and/or seismic loading and should be decreased by one-fourth for dead load only. Adjacent footings founded at different bearing levels should be so located that the slope from bearing level to bearing level is flatter than one horizontal to one vertical. -- I SCSRT 13789 December 17, 1980 Page 7 All continuous footings should be reinforced with at least one 14 rebar located at both the top and bottom of the footing. LATERAL RESISTARCE: Resistance to lateral loads may be provided by fric- tion at the base of the footing and by passive pressure against the adja- cent. soil. For concrete footings on compacted soil, a coefficient of friction of 0.40 may be used. For calculating passive pressure, an equiv- alent fluid unit weight of 300 pounds per cubic foot may be used. Passive pressure should not exceed 3000 pounds per square foot. When combining frictional and passive resistance, the latter should be reduced by one- third. SETTLEMENT CHARACTERISTICS: The anticipated total and/or differential settlements for the proposed construction should be less than the settle- ments necessary to produce structural distress, provided the reconrnenda- tions contained herein are followed. EXPANSIVE CHARACTERISTICS: The prevailing foundation soils were found to be nondetrimentally expansive and will not require special consideration and/or design. PAVEMENT REUMEWDATIONS The design of the pavement section was beyond the scope of this project. However, the following recomnendations are submitted as preliminary guide- lines for pavement construction. The subgrade soils to a depth of at least 12 inches should be densified to at least 90%. Paved areas should be protected from moisture migrating under the pavement from adjacent water sources such as planted or grass areas. Saturation of the subbase soils could result in pavement failure. Further, all paving materials and methods of construction should conform with good grading practices and with the minimum requirements of the governing agency. -- SCS&T 13789 December 17. 1980 Page 8 The pavement section in front of trash enclosures should be thickened to reeflect the additional loads received due to heavy trucks servicing the area. Subgrade soils beneath this thickened section should be compacted to 95% to a depth of 24 inches. LIHITATIW REVIEW, OBSERVATIDN ARD TESTIIG The reconendations presented in this report are contingent upon our review of final plans and specifications. As required by the State of California, Division of Real Estate, the soil engineer and engineering geologist should review and verify the compliance of the final grading plan with this report and with Chapter 70 of the Uniform Building Code. It is reconended that the soil and foundation engineer be retained to provide continuous soil engineering services during the earthwork opera- tions. This is to observe compliance with the design concepts, specifi- cations or recormrendations and to allow design changes in the event that subsurface conditions. differ from those anticipated prior to start of construction. UNIFORHITY OF CONDITIONS The recornnendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluation of the subsur- face soil conditions encountered at the subsurface, exploration locations and the assumption, that the soil conditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations and/or cut and fill slopes may be influenced by undis- closed or unforeseen variations in the soil conditions that may occur in 1 SCSET 13789 December 17, 1980 Page 9 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 soils engineer so that he may make modifi- cations if necessary. CHANGE IN SCOPE This office should be advised of any changes in the project scope or proposed site grading so that It may be determined if the recomnendations contained herein. are valid. This should be verified in writing or modi- fied by a written addendum. TX-HE LIMITATIONS The findings of this report are valid as of this date. Changes in the condition of a property can, however, occur with the passage of time, whether they be due to natural processes or the work of man on this or 'adjacent propertles. In addition, changes in the State-of-the-Art and/or Government Codes may occur. Due to such changes, the findings of this report may be invalidated wholly or in part by changes beyond our control. Therefore, this report should not be relied upon after a period of two years without a review by us verifying the validity of the conclusions and recommendations. YARRANTY The client should recognize the inherent risks connected with the con- struction of improvements to real property. In the performance of our professional services, we comply with the standard of care and skill ordinarily exercised under similar circumstances by members of our pro- fession practicing in the same or similar localities. Our services are to SCS8T 13789 December 17, 1980 Page 10 consist ~of professional consultation and observation only, and no war- ranty, express or implied, is made or intened in connection with the work to be performed by us or by the proposal for consulting or other services or by the furnishing of oral or written reports or findings. CLIENT’S RESPOiWBILIl Y It is the responsibi their representatives lity of Blankenshlp Development Company, Inc., or to make sure that the information and recomnenda- tions contained herein are brought to the attention of the engineer and architect for the project and incorporated into the project's plans and specifications. It is further their responsibility to take the necessary mqasure to ascertain that the contractor and his subcontractors carry out such recommendations during construction. FIELD EXPLORATIONS Three subsurface explorations were made at the locations indicated on the attached Plate Number 1 on December 10, 1980. These explorations con- sisted of trenches dug by means of a backhoe. The field work was con- ducted under the observation of our engineering geology personnel. The explorations were carefully logged when made. These logs are pre- sented on the following Plate Numbers 2 and 3. The soils are des-cribed in accordance with the Unified Soils Classification System as illustrated on the attached simplified chart Plate 4. In addition, a verbal textural description, the wet color, the apparent moisture and the density or consistency are presented. The density of granular material is given as either very loose, loose, medium dense, dense or very dense. The consistency of silts or clays is given as either very soft, soft, medium stiff, stiff, very stiff, or hard. ..--_. -_..-m.. _.,_ -_.. _..- --~ SCS&T 13789 December 17, 1980 Page 11 Disturbed and undisturbed samples of typical and representative soils were obtained and returned to the laboratory for testing. "Undisturbed" sam- ples were taken as chunks at selected depths in the exploration trench- es. LABORATORY TESTIllG Laboratory tests were performed in accordance with the generally accepted American Society for Testing and Materials (A.S.T.M.) test methods OY suggested procedures. A brief description of the tests performed is presented below: a) MOISTURE-DENSITY: Field moisture content and dry denslty were determined for representative undisturbed samples. 'This infor- mation 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 field moisture content is determined as a percentage of the soil's dry weight. The results are sunrnarized in the trench logs. CLASSIFICATION: Field classifications were verified in the laboratory by visual examination. The final soil classifica- tions are in accordance with the Unified Soil Classification System. DIRECT SHEAR TESTS: Direct shear tests were performed to determine the failure envelope based on yield shear strength. The shear box was designed to accomodate a sample having a diameter of 2.375 inches or 2.50 inches and a height of 1.0 inch. Samples were tested at different vertical loads and at saturated moisture content. The shear stress was applied at a constant rate of strain of a‘pproximately 0.05 inches per min- ute. The results of ,these tests are presented on attached Plate Number 5. SCSAT 13789 December 17, 1980 Page 12 . d) COWACTION TEST: The maximum dry density and optimum moisture content of typical soils were determined in the laboratory in accordance with A.S.T.M. Standard Test D-1557-70, Method A. The results of these tests are presented on the attached Plate Number 5. e) GRAIN SIZE DISTRIBUTION: The grain size distribution was determined for representative samples of the native soils in accordance with A.S.T.M. Standard Test D-422. The results of these tests are presented on Plate Number 6. . _. - - - - -. _. - . . . - %j 9 I 3 m&o bLcG. IJzz7 I I ‘ZWJ - I G -- [C. &XS 7: OXZtZ ’ I I &/Lont; 1 / 1 L I--_1 J bOUTWtRN CALIFORNIA Blankenship Office Building SOIL & TELlTlNO , INC. . ..O ","."D.L. .T"..V 2910 Jefferson ..W DI.rn0. CILICOINIA ..?.O Carlsbad, California Bv .lC I"= 12-17-80 I- CJ- No t 13789 . 1 Plate No. 1 Tre&h Numbers 1 DE~TION BROWN, HUMID TO MOIST, LOOSE TO DENSE, SILTY SANG CONTAINING ROOTS (Topsoil) Y M RED-BROWN, MOIST, MEDIUM DENSE TO DENSE, SILTY, POORLY GRADED SAND BOTTOM Trench Nutier 2 OISCRIPTION BROWN,HUMID, LOOSE TO MEDIUM DENSE. SILTY SAND GRADES TO: RED-BROWN, MOIST, DENSE, SILTY, POORLY GRADED SAND 105.6 3.2 (Moderately cemented) 118.9 5.6 114.9 4.5 EOUTHERN CALIFORNIA Blankenship Office Building SOIL L TEETINO, INC. . ..D “8V.IO.L. .T”..l 2910 Jefferson .AN PI.00. CILICOINIA ..*.o Carlsbad, Callfornia m CRB JOB N0. 13789 ONE 12-10-BO * Plate No. 2 Trbnch Number 3 DESCRIPTION Y SROWN, HUMID, LOOSE TO MEDIUM DENSE, SILTY SAND XtADES TO: RED-BROWN, MOIST. DENSE, SILTY, POORLY GRADED SAND 112.1 MODERATELY CEMENTED WEAKLY CEMENTED 116.5 M 6.1 BOTTOM I LEGEND : "Undisturbed" Sample Location : Bulk Sample Locatfon Y: Natural Dry Density (pcf) M: Natural Moisture Content (X of Y) * Field Density Test Locatic I, INC. 2910 Jefferson / -I-Y "IYIIYI... - I'"..T .AN OI.00. C.LWOCINl& ..?rnO Carlsbad. California SOUTHERN CALIFORNIA SOIL & TESTJNQ ---- -...- ---. - -- Blankenship Office Building BY CRB OA= li-lo-80 JoB No’ 13789 * Plate No. 3 - - - ir, ,- UNIFIED SOIL CLASSIFICATION CHART :N SOIL DESCRIPTION 11 ,: COARSE GRAINED. More than half of material is larger than No. 200 sieve size. ;ti GRAVELS CLEAN GRAVELS 1, man half I$ of Coarse fraction is larger than No. 4 sieve size but GRAVELS WITH FINES :J smaller than 3". (Appreciable amount of fines) SANDS CLEAN SANDS Fbrethan half of coarse fraction is smaller than No. 4 SANDS WITH FINES (Appreciable amount of fines) II II. FINE GRAINED, More than half of material is smaller than No. 200 sieve size. 1 SILTS AND CLAYS ML Liquid Limit less than 50 GROUP SYMROL SILTS AND CLAYS Liquid Limit greater than 50 HIGHLY ORGANIC SOILS GW GP GM GC SW SP SM SC CL OL MH CH OH PT TYPICAL NAMES Well graded gravels. qravel-sand mix- tures, little or no fines. Poorly graded 9ravels. gravel sand mjxtures, little or no fines. Silty gravels, poorly graded gravel- sand-silt mixtures. Clayey gravels, poorly graded gravel- sand, clay mixtures. Well graded sand, gravelly sands, little or no fines. Poorly graded sands, gravelly sands, little or no fines. Silty sands, pooyly'graded sand and silt'mlxtures. Clayey sands, poorly graded sand and clay mixtures. Inorganic sjlts and very fine sands, rock flour, iandy sflt or clayey- silt-sand mixtures with slight . plasticity Inorganic clays of low to medium medium plasticity, gravelly clays, sandy clays, silty clays, lean clays. Organic silts and organic silty clays of low plasticity. Inorganic silts, mfcaceous or diato- maceous fine sandy or silty soils. elastic silts. Inorganic clays of high plasticity, fat clays. Organic clays of medtwn to hi9h plasticity. Peat and other highly organic soils. SOUTHERN CALIFORNIA SOIL (L TEBTIND, INC. . ..D “,“.“O~L. .1m..v "AN DI.00. c-L,CPmNIa ..?.O Blankenship Office Building 2910 Jefferson DIRECT SHEAR TEST RESULTS MAXIMUM DENSITY end OPTIMUM MOISTURE CONTENT AsrM 1557-70 METHOD A c SAMPLE DESCRIPTION T 1 @ 3-4 Red-Brown Si 1 ty Sand maxImum ootlmum duwy moleturn (W) Conmll (k) 133.6 9.1 mOUTC(ERN CALIFORNIA LIOIL L TLBTINO , INC. . ..II “I”.“DAL. .T”..T .AN DI.00. ~ALICOINI. ..,.a Blanketiship Office Building ’ BY AFB DATE 12-17-W I ~~ Y a E 2 cn N m 0 Y II E 5 P PARTICLE SIZE LIMITS SRAYEL 1 smo 8s.T OR CLAY ceo(Fho jcunlwlr’l Ph. I I WL) 3lr 3/4iD. M lkio Rdo IkzDo I#.* STAIIOARD slfvt alzc 'L :L 'I L L 1 1 1 1 i .:!I P ” , Appendix A, Page One December 17, 1980. SCS&T 13789 RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS GENERAL INTENT The intent of these specifications is to establish procedures for clearing, compacting natural ground, preparing areas to be filled and placing and compacting fill soils to the lines and grades shown on the accepted plans. The recommendations contained in the preliminary soil investigation report and/or the attached Special Provisions are a part of the Recommended Grading Specifications and shall supersede the provisions contained hereinafter in the case'of conflict. INSPECTION AND TESTING A qualified soil engineer shall be employed to inspect a,nd test the earthwork in accordance with these specifications. It will be necessary that the soil engineer or his representa- tive provide adequate inspection so that he may certify that the work was or was not accomplished as specified. It shall be the responsibility of the contractor to assist the soil engineer and to keep him appraised of work schedules, changes and new information and data so that he may make these certifications. If, in the opinion of the soil engineer, substandard condi- tions are encountered, such as qu~estionable soil, poor moisture content, inadequate compaction, adverse weather, etc., he will be empowered to either stop construction until the conditions are remedied or corrected or recommend rejection '~'-~. of the work. Soil tests used to determine the degree of compaction will . be performed in accordance with the following American I’ .L L 1 1 1 .1 ’ .I , Appendix A, Page Two December 17, 1980. Society for Testing and Materials test methods: Maximum Density & Optimum Moisture Content - A.S.T.M. D- 1557 - 70. Density of Soil In-Place - A.S.T.M. D - 1556 - 64. SCS&T 13789 PREPARATION OF AREAS TO RECEIVE FILL All vegatation, brush and debris shall be removed, piled and burned or otherwise disposed of. After clearing, the natural ground shall be scarified to a depth of 6 inches, brought to the proper moisture content, compacted and tested for the, minimum density specified in the Special Provisions or'the . recommendation contained in the preliminary soil investigation report. When the slope of the natural ground receiving fill exceeds 20% (5 horizontal units to 1 vertical unit), the original ground shall be stepped or benched. Benches shall be cut to a firm competent soil condition. The lower bench shall be at least 10 feet wide and all other benches at least 6 feet wide. The horizontal portion of each bench shall be compacted prior to receiving fill as specified .herein before for compacted natural ground. Ground slopes flatter than 20% shall be benched when considered necessary by the soil engineer. FILL MATERIAL Materials placed in the fill shall be approved by the soil engineer and shall be free of vegetable matter and other deleterious substances. Granular soil shall contain sufficient fine material to fill the voids. The definition and disposition of oversized rocks, expansive and/or detrimental soils are covered in the Special Provisions. Expansive soils, soils . of poor gradation or strength characteristics may be thoroughly t- - :_ 1 'I L L 1 .I 1 j j Appendix A, Page Three December 17, 198D. SCS&T 13789 mixed with other soils to provide satisfactory fill material, but only with the explicit consent of the soil engineer.. PLACING AND COMPACTION OF FILL Approved fill material shall be placed in areas prepared to receive fill in layers not to exceed 6 inches in compacted thickness. Each layer shall have a uniform moisture content in the range that will allow the compaction effort to be efficiently applied to achieve the specified degree of compaction. Each layer shall be uniformly compacted to a minimum specified density with adequately sized equipment, either specifically designed for soil compaction or of. proven reliability. The minimum degree of compaction to be achieved is specified in either the Special Provisions or the recommendations contained in the prelimimary soil investigation report. Field tests and inspections to check the degree of compaction of the fill will be taken by the soil engineer or his representative. The location and frequency of the tests shall be at the soil engineer's discretion. In general, the density tests will be made at an interval not exceeding 2 feet in vertical rise and/or 500 cubic yards of embankment. SEASON LIMITS Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy rain, filling operations shall not be resumed until the proper moisture content and density of the fill has been achieved. Damage resulting from weather shall be repaired before acceptance of work. Appendix A, Page Four December 17, 1980. SCS&T 13789 RECOMMENDED GRADING SPECIFICATIONS SPECIAL PROVISIONS The minimum degree of compaction to be obtained in compacting natural ground, in the compacted fill, and in the compacted backfill shall be 90 percent. Detrimentally expansive soil is defined as soil which will swell more than 3 percent against a pressure of 150 pounds .per square foot from a condition of 90 percent pf maximum dry density and optimum moisture content to saturation. Oversized fill material is defined as rocks or lumps over 6 inches in diameter. At least 40 percent of the fill soils shall pass through a No. 4 U.S. Standard Sieve. Transition Lots: Where transitions between cut and fill occur within the proposed building pad, the cut portion should be undercut a minimum of one foot below the base of the proposed footings and recompacted as structural backfill. I C....IvYC”L. c .,,.- -_ .,,. =-,, ..,- -r^-.h.- a-.-