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HomeMy WebLinkAboutCT 72-20; Glasford Residence Unit 3 Lot 477; Soils Report; 1983-02-07SOIL INVESTIGATION PROPOSED GLASFORD RESIDENCE LOT NUMBER 477, TRACT 72-20, UNIT NUMBER 3 CARLSBAD, CALIFORNIA PREPARED FOR Warner Glasford 7969 Engineer Road, #202 San Oiego, California 92111 PREPARED BY Southern California Soil & Testing, Inc. Post, Office Box 20627 6280 Riverdale Street San Diego, California 92120 February 7, 1983 Warner Glasford 7969 Engineer Road, #202 San Diego, California 92111 SCS&T 14127 Report No. 1 SUBJECT: Soil Investigation, Proposed Glasford Residence, Lot Number 477, Tract 72-20, Unit No. 3, Venado Street, Carlsbad, Calif- ornia. Gentlemen: In accordance with your request, we have performed an investigation of the soil conditions at the subject site. We are transmitting herewith a report of this investigation. The analysis of our findings is intended to provide the required informa- tion to design the foundation and grading plans for the proposed develop- ment. In general, we found the site underlain by dense, fractured metavolcanic rocks confined in a sand and clay matrix. If you have any questions after reviewing our report, please do not hesi- tate to contact this office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, SOUTHERN CALIFORNIA SOIL 8 TESTING, INC. /? d-,h Curtis R. Burdett, C.E.G. #IO90 RRR:CRB:m cc: (6) Submitted (1) SCS&T, Escondido SOUTHERN CALIFORNIA 501L AND TESTINO. I N 0. TABLE OF CONTENTS PAGE Project Description and Scope ............................................ 1 Findings ................................................................. 2 Site Description ..................................................... 2 General Geology and Subsurface Conditions ............................ 2 Geologic Setting and Soil Description ........................... 2 Tectonic Setting ................................................ 2 Geologic Hazards ..................................................... 3 Recommendations and Conclusions .......................................... 3 Site Preparation ..................................................... 3 General ......................................................... 3 Earthwork ....................................................... 4 Foundations .......................................................... 4 General ......................................................... 4 Settlement Characteristics ...................................... 4 Limitations .............................................................. 4 Review, Observation and Testing ...................................... 4 Uniformity of Conditions ............................................. 5 Change in Scope ...................................................... 5 Time Limitations ..................................................... 5 Professional Standards ............................................... 6 Client's Responsibility .............................................. 6 Field Explorations ....................................................... 6 ATTACHMENTS PLATES Plate 1 Plot Plan Plate 2 Unified Soil Classification Chart Plate 3 Trench Log APPENDIX Recommended Grading Specification and Special Provisions REPORT OF SOIL INVESTIGATION PROPOSED GLASFORD RESIDENCE LOT NUMBER 477, TRACT 72-20, UNIT NUMBER 3 CARLSBAD, CALIFORNIA PROJECT DESCRIPTION AND SCOPE This report presents the results of our soil investigation for a proposed single-family residence which is to be located near the intersection of Venado Street and Cadencia Street in the La Costa area of Carlsbad, Calif- ornia. It is our understanding that a one or two story, wood-framed residence is planned for the site. It is further understood that maximum cuts and fills on the order of 5 to 10 feet are anticipated. The site configuration and test trench location are shown on Plate Number 1 of this report. This soil investigation was undertaken to: a) Determine the physical properties of the prevailing soils includ- ing their supporting capacities and settlement characteristics. b) Provide design information regarding foundations and site grad- ing. SOUTHERN CALIFORNIA s 0 I L AND TESTING. INC. SCS&T 14127 February 7, 1983 Page 2 c) Determine potential construction difficulties and provide recom- mendations concerning these difficulties. FINDINGS SITE DESCRIPTION The subject site is a trapezium shaped lot, approximately 0.96 acre in surface area that fronts on Venado Street in the La Costa area of Carls- bad. Venado Street forms the eastern boundary and the lot is bordered on all- other sides by undeveloped residential lots. The lot slopes moder- ately to the west with drainage being accomplished by sheetflow. Vegeta- tion consists of a moderate to heavy growth of native plants and shrubs. The lot is largely in a natural state except for a fill bank (approxi- mately six to eight feet high) which is associated with the construction of Venado Street on the eastern boundary of the site. GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is underlain by metavolcanic rocks of the Jurassic Santiago Peak Volcanics and associated residual and colluvial soils. The weathering surface on the metavolcanic rock is highly irregular as observed in outcrops and cuts made in the surrounding area. The topsoil/colluvial cover developed on the metavol- canic rock ranges in thickness from locally absent to several feet. Much of this topsoil/colluvial cover is comprised of expansive clayey sand and clayey gravel. TECTONIC SETTING: No faults are known to traverse the subject site and the faults mapped on the La Costa area are generally classified as inac- tive. However, it should be recognized that much of Southern California is characterized by major, active fault zones that could possibly affect SCS&T 14127 February 7, 1983 Page 3 the site. The nearest of these is the Elsinore Fault Zone, located approx- imately 24 miles to the northeast. In addition, it should be noted that the extension of the Rose Canyon Fault Zone, a potentially active zone, lies approximately 8 miles to the west. GEOLOGIC HAZARDS: The subject site is located in an area which is rela- tively free of potential geologic hazards. The most likely hazard to affect the site is groundshaking as a result of movement along one of the major, active fault zones mentioned previously. Based on a maximum prob- able earthquake of 7.3 magnitude along the Elsinore Fault Zone, maximum ground acceleration could be on the order of 0.20 g. There is a remote possibility that movement could occur along the Rose Canyon Fault Zone during the life of the proposed structure and subject the site to ground accelerations even higher than those attributed to the Elsinore Fault Zone. However, it is our opinion that due to the current classification of the Rose Canyon Fault Zone as only potentially active instead of ac- tive, it should not be used for design purposes for single-family resi- dential structures. RECOWENDATIONS AND CONCLUSIONS SITE PREPARATION GENERAL : Due to the apparent competent nature of the native soils at this site, it is our opinion that no special site preparation procedures will be necessary. We do recommend, however, that the surface soils be scari- fied, watered to at least optimum requirements and compacted to a minimum of 90% relative compaction. The horizontal extent of this recomnendation should include all areas to receive fill and/or structural loads. Con- sideration should also be given to undercutting the cut portion of the building pad to a depth of two feet to acconnnodate future utility lines. The undercut material, may then be replaced as a compacted fill densified to at least 90%. We further suggest that all rocks in excess of six inches in diameter be located at least 3 feet below finished grade. ~S”llTYCDN CA, ,lrnaP.d,a F”,, AhIlT -TCET,h,,-z I..,? SCS&T 14127 February 7, 1983 Page 4 EARTHWORK: All earthwork and grading contemplated for site preparation should be accomplished in accordance with the attached Recommended Grading Specifications and Special Provisions. All special site preparation recommendations 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 pavements should be compacted to a minimum of 90% of its maximum dry density. The maximum dry density of each soil type should be deter- mined in accordance with A.S.T.M. Test Method 1557-78, Method A or C. FOUNDATIONS GENERAL: It is our opinion that the proposed residence may be supported by spread footings. Due to the on-site soils possessing varying degrees of expansion potential, we recommend that the footings be dimensioned upon completion of site grading. As a preliminary design, we recommend that all footings be founded at least 18 inches below adjacent grade with a minimum width of 12 inches. It is also recommended that all continuous footings be reinforced with at least one No. 4 bar top and bottom For foundation design purposes an allowable soil bearing pressure of 2000 psf may be used. SETTLEHENT CHARACTERISTICS: Provided that the recomnendations contained in this report are followed, it is our opinion that the resuling settle- ments should be within tolerable limits. LIMITATIONS REVIEW, OBSERVATION AND TESTINB It is recommended that Southern California Soil & Testing, Inc. be re- tainned to provide continuous soil engineering services during the earth- s n UT&-! F mhl PA I I C” D r.I I a 5”, I AM I-, T c E7 I -I e 5 +.I r SCS&T 14127 February 7, 1983 Page 5 work operations. This is to observe compliance with the design concepts, specifications or recommendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior to start of construction. UNIFORUITY OF CONDITIONS The recommendations 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 frm 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 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 recommendations contained herein are appropriate. This should be verified in writing or modified by a written addendum. TINE LIblITATIONS 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 properties. In addition, changes in the State-of-the-Art and/or SOUTYFRN CAIIFOF1NI~ IOIL AN” TFGT,hlr_ ,Wr- SCS&T 14127 February 7, 1983 Page 6 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 suitability of the conclusions and reconmiendations. PROFESSIONAL STANDARDS In the performance of our professional services, we comply with that level of care and skill ordinarily exercised by members of our profession cur- rently practicing under similar conditions and in the same locality. The client recognizes that subsurface conditions may vary from those encoun- tered 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 will be responsible for those data, interpretations, and recommendations, but shall not be respon- sible for the interpretations by others of the information developed. Our services consist of professional consultation and observation only, and no warranty of any kind whatsoever, express or implied, is made or intended in connection with the work performed or to be performed by us, or by our proposal for consulting or other sevices, or by our furnishing of oral or written reports or findings. CLIENT'S RESPONSIBILITY It is the responsibility of Warner Glasford, or his representatives to ensure that the information and recommendations 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 his responsibility to take the necessary measures to ensure that the contractor and his subcontractors carry out such recommendations during construction. ,- SCS&T 14127 February 7, 1983 Page 7 FIELD EXPLORATIONS One subsurface exploration was made at the locations indicated on the attached Plate Number 1 on January 26, 1983. This exploration consisted of a trench dug by means of a backhoe. The field work was conducted under the observation of our engineering geology personnel. The exploration was carefully logged when made. The log is presented on the following Plate Number 3. The soils are described in accordance with the Unified Soils Classification System as illustrated on the attached simplified chart on Plate Number 2. In addition, a verbal textural de- scription, the wet color, the apparent moisture, and the density or con- sistency are provided. The density of granular soils 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. Disturbed and "undisturbed" samples of typical and representative soils were obtained and returned to the laboratory for testing. c”II.syc~., -.I Ic-mLIIA C”,, *,.,n TFEIIwIe ILIP 0 2 Y h 0 2 Y 476 ~ i 8 ,0° Q0 ‘L -70 E:%:: LOCATION SOUTHERN CALIFORNIA Proposed Glasford Residence SOIL & TESTING, INC. Lot No. 477, Tract 72-20, Unit No. 3 .PrnD CI,"tLrn)DALE .TC)rnET s*N OICOP, OALIEOmNtP eP,PO Venado Street Carlsbad, California BY SMS IRATE 2-3-83 I JOB NO. 14127 Plate No. 1 SUESURFACE EXPLORATION LEGEND UNIPIED SOIL cIAssrp1cA*roN CnAuT SOUL DESCRIPTICIH GROUP SYWBO‘ TYPICAL NAMES 1. COIRSL OPAINED. More t!mn half of material is w than NO. 200 sieve *ire. w c7.L.N wuvas norc tll.n h.lf Of coarse fraction is 1.rg.r th.” NO. 4 sieve sire but sm.11er than 3’. GRAVELS WITH FINES ,*ppreci.blc .mcu”t of fines) gNJ$ &ma SANDS “ore th.n h.lf Of coarse fraction is *m.11.r than HO. 4 sieve *ire. SLNDS “ITH PniEs v.ppreciable .mount Of fines) 11. PINE GRAINEED, ml-e t.h.” half et material is w than NO. 200 sieve sire. SILTS Am CLAYS Liquid limit less than 50 SILTS Am CLAYS Liquid limit greater than 50 HIGHLY cGAN*c smrs (+r GP GEI GC SW SP St4 SC ML CL OL IQ1 CH 0” m “ell gr.*cd gr.ve1s. grwa1- *an* mixtures, little or no fines. Poorly graded gravels, grave1 *an* mixtures, little or no fines. silty gravel*, poorly graded gravel-sand-silt mixtures. Clayey gravels, p.Jor1y graded gr.val-sand, clay mixture*. we11 graded *.nd,gr.“elly **“da, little or no finer. Poorly graded s.“ds,gr.velly S.“dS, 1itt1* or “0 fires. Silty sands. poorly graded sand and silt mixtures. Clayey sands, poorly graded sand an.3 c1.y mixtures. rnc.rganic silts and very fine sands, rock flour, randy silt or clayey-silt-sand mixtures with slight plast- icity horganic clays of lar to medium pla*tieity.qravelly flays, sandy clays.*ilty clay*, lean clays. organic l iles and organic silty clays of lcw pla*ticity Inorganic silts, micaceous or diatomaccoua fine sandy or *ilty sofl,*, elastic silts. morganic clays Of high plasticity. fat clays. Organic clays of medium tr2 hiah dasticitv. - _ Peat and other highly organic S.zF,.. ,. ;.. ,~ _~. ,.. ___,., _” ___I..-.-.._I_ ..-. ____II._-----.--~.I__I___ l___ c - Water level at time of excavation or as indicated us - Undisturbed, driven ring sample or tube sample CK - Undisturbed chunk sample BG - Bulk sample SOUTHERN CALIFORNIA SOIL a TESTINQ , INC. . ..a “IVmmmA‘. .+il..7 .AN DI.00. CILICOONIA ..,.D I . -_ Proposed Glasford Residence Lot No. 477, Tract 72-20, Unit No. 3 Venado Street Carlsbad, California Bv DATE 2-3-83 IOB NO. 14127 Plate No. 2 ~. ..,~,..L- ,~ ._, .._ f!l G ,” ,T TRENCH NUMBER 1 5” I- 0 * > t 2 i 7 zzt z w- 5 :; v, ; z = w-‘- EC”; z- ELEVATION :: ;: 2” ‘,” ; p’ IJl Y :;;o :: ljjw -a : ; I 2 :: 2gg 5; ii’ : :, 2 z = 0 0 c 0 DESCRIPTION 0 0 ‘ SMI Silty Sand and Gravel Moist 'led. Dense GM (Topsoil) 1 GC/ Silty and Clayey Gravel Moist Jery Dense GM (Santiago Peak Volcanics) 2- 3 SOUTHERN CALIFORNIA .SUBSURFACE EXPLORATlON LOG SOIL & TESTING,INC. LOGGED BY: DATE LOGGED: CRB 1-26-83 JOB NUMBER: 14127 Plate No. 3 SCS&T 14127 February 7, 1983 Appendix A, Page 1 GLASFORD RESIDENCE, LOT NO. 477, TRACT 72-20, UNIT NO. 3 RECOMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS GENERAL INTENT The intent of these specifications is to establish procedures for clear- ing, 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 recormnendations contained in the preliminary soil investiga- tion 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. These'specifications shall only be used in conjunction with the soil report for which they are a part. No deviation from these specifications will be allowed, except where specified in the soil report or in other written communication signed by the Soil Engineer. OBSERVATION AND TESTING Southern California Soil & Testing, Inc. shall be retained as the Soil Engineer to observe and test the earthwork in accordance with these speci- fications. It will be necessary that the Soil Engineer or his representa- tive provide adequate observation so that he may provide an opinion that the work was or was not accomplished as specified. It shall be the re- sponsibility of the contractor to assist the soil engineer and to keep him apprised 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 soil report are encountered during the grading operations, the Soil Engineer shall be contacted for further recommendations. SCS&T 14127 February 7, 1983 Appendix A, Page 2 If, in the opinion of the Soil Engineer, substandard conditions are en- countered, such as; questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse weather, etc., he will be empower- ed to either stop construction until the conditions are remedied or cor- rected or recommend rejection of this work. Test methods used to determine the degree of compaction should be per- formed in accordance with the following American Society for Testing and Materials test methods: .- Maximum Density & Optimum Moisture Content - A.S.T.M. D-1557-78. Density of Soil In-Place - A.S.T.M. D-1556-64 or A.S.T.H. D-2922. All densities shall be expressed in terms of Relative Compaction as deter- mined by the foregoing A.S.T.M. testing procedures. PREPARATION OF AREAS TO RECEIVE FILL All vegetation, brush and debris derived from clearing operations shall be removed, and legally disposed of. All areas disturbed by site grading should be left in a neat and finished apperance, free from unsightly debris. Any abandoned buried structures encountered during grading operations must be totally removed. All underground utilities to be abandoned beneath any proposed structure should be removed from within 10 feet of the structure and properly capped off. The resulting depressions from the above des- cribed procedures should be backfilled with acceptable soil that is com- pacted to the requirements of the Soil Engineer. This includes, but is not limited to, septic tani:s, fuel tanks, sewer lines or leach lines, SOUTHERN [3AL,FORNIA SOIL AND TEST!NG, INC KS&T 14127 February 7, 1983 Appendix A, Page 3 storm drains and water lines. Any buried structures or utilities not to be abandoned should be investigated by the Soil Engineer to determine if any special recommendation will be necessary. All water wells which will be abandoned should be backfilled and capped in accordance to the requirements set forth in the Geotechnical Report. The top of the cap should be at least 4 feet below finish grade or 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 Soil Engineer and/or a qualified Structural Engineer. When the slope of the natural ground receiving fill exceeds 20% (5 hori- zontal 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 or 1 l/2 times the equipment width which ever is greater and shall be sloped back into the hillside at a gradient of not less than two (2) percent. All other benches should be at least 6 feet wide. The horizontal portion of each bench shall be compacted prior to receiving fill as specified hereinbefore for compacted natural ground. Ground slopes flatter than 20% shall be benched when considered necessary by the Soil Engineer. After clearing or benching, the natural ground in areas to be filled shall be scarified to a depth of 6 inches, brought to the proper moisture con- tent, compacted and tested for the minimum degree of compaction in the Special Provisions or the recommendation contained in the preliminary soil investigation report. All loose soils in excess of 6 inches thick should be removed to firm natural ground which is defined as natural soil which possesses an in-situ density of at least 85% of its maximum dry density. SOUTHERN CALIFORNIA 501L AND TE5TlNG. INC SCS&T 14127 February 7, 1983 Appendix A, Page 4 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. Gran- ular soil shall contain sufficient fine material to fill the voids. The definition and disposition of oversized~ rocks, expansive and/or detrimen- tal soils are covered in the soils report or Special Provisions. Expan- sive soils, soils of poor gradation, or soils with low strength character- istics may be thoroughly mixed with other soils to provide satisfactory fill material, but only with the explicit consent of the soil engineer. Any import material shall be approved by the Soil Engineer before being brought to the site. 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 compac- tion effort to be efficiently applied to achieve the specified degree of compaction. Each layer shall be uniformly compacted to the minimum speci- fied degree of compaction with equipment of adequate size to economically compact the layer. Compaction equipment should either be 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 preliminary soil investigation report. When the structural fill material includes rocks, no rocks will be allowed to nest and all voids must be carefully filled with soil such that the minimum degree of compaction recomnended in the Special Provisions is SOUTHERN CALIFORNIA 5DIL *ND TE5TING. INC SCS&T 14127 February 7, 1983 Appendix A, Page 5 achieved. The maximum size and spacing of rock permitted in structural fills and in non-structural fills is discussed in the soil report, when applicable. Field observation and compaction tests to estimate the degree of compac- tion 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. When the compaction test indicates that a particular layer is less than the required degree of compaction, the layer shall be reworked to the satisfaction of the Soil Engineer and until the desired relative compaction has been obtained. Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction by sheepsfoot rollers shall be at vertical intervals of not greater than four feet. In addition, fill slopes at ratios of two horizontal to one vertical or flatter, should be track- rolled. Steeper fill slopes shall be over-built and cut-back to finish contours. Slope compaction operations shall result in all fill material six or more inches inward from the finished face of the slope having a relative compaction of at least 90% of maximum dry density or that speci- fied in the Special Provisions section of this specification. The compac- tion operation on the slopes shall be continued until the Soil Engineer is satisfied that the slopes will be stable in regards to surficial stabil- ity. Slope tests will be made by the Soils Engineer during construction of the slopes to determine if the required compaction is being achieved. Where failing tests occur or other field problems arise, the Contractor will be notified that day of such conditions by written cormnunication from the Soil Engineer in the form of a daily field report. SOUTHERN CALIFORNIA 901L AND TESTING. IUC. SCS&T 14127 February 7, 1983 Appendix A, Page 6 If the method of achieving the required slope compaction selected by the Contractor fails to produce the necessary results, the Contractor shall rework or rebuild such slopes until the required degree of compaction is obtained, at no additional cost to the Owner or Soils Engineer. CUT SLOPES The Engineering Geologist shall inspect all cut slopes excavated in rock or .lithified formational material during the grading operations at inter- vals determined at his discretion. If any conditions not anticipated in the preliminary report such as perched water, seepage, lenticular or confined strata of a potentially adverse nature, unfavorably inclined bedding, joints or fault planes are encountered during grading, these conditions shall be analyzed by the Engineering Geologist and Soil Engi- neer to determine if mitigating measures are necessary. Unless otherwise specified in the soil and geological report, no cut slopes shall be excavated higher or steeper than that allowed by the ordinances of the controlling governmental agency. ENGINEERING OBSERVATION Field observation by the Soil Engineer or his representative shall be made during the filling and compacting operations so that he can express his opinion regarding the conformance of the grading with acceptable standards of practice. The presence of the Soil Engineer or his representative or the observation and testing shall not release the Grading Contractor from his duty to compact all fill material to the specified degree of compac- tion. SOUTHL~N CALIFORNIA 501L ANO TFSTING. INC SCS&T 14127 February 7, 1983 Appendix A, Page 7 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 materials can be achieved. Damaged site conditions resulting from weather or acts of God shall be repaired before acceptance of work. REC0fMENDEI.l GRADING SPECIFICATIONS-SPECIAL PROVISIONS The minirmm degree of compaction to be obtained in compacting natural ground, in the compacted fill, and in the compacted backfill shall be at least 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 condi- tion of 90 percent of maximum dry density and air dried 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. SOUTHEr?N CALIFOl?NIA 501L AND TE5TING. INC