Loading...
HomeMy WebLinkAboutTract Map 3646 Lot 21 Preliminary Soils , ' . . ~ ~"jt, pc eJ--/ )../)0,1.6 612.. W. C. HOBBS, CONSULTING ENGINEER 25489 BLACKWOOD ROAD MURRIETA, CALIFORNIA 92563 (909) 696-7059 L-\~\\)A Dov<:.err I MI. ;PI,iI Lenis Date: December 30,1999 Project No: 99128-1 RECEIVED MAY 2 1 2002 CITY OF TEMECULA ENGINEERING DEPARTMENT 'Temecula, California 92590 I Subject: Preliminary Soil Engineering Evaluation for Proposed Residence Located at East Vallejo Road and Ynez Road, City of Temecula, California I Dear Mr. Lewis, I Pursuantto your authorization and a requirement by the City ofTemecula, a limited soil engineering I evaluation was conducted on the subject lot to determine the distribution and engineering : characteristics of earth materials present. The results of field exploration, together with the results : of the laboratory tests, are summarized in the attached appendix. I .Additional information provided herein includes preliminary foundation design for proposed I residential construction. i Accompanying Maps and Appendices I Attached Appendix A, Summary of Laboratory and Field Test Results I Attached Appendix S, General Earthwork and Grading Specifications I Plate 1, Location ofTestTrench I Scope of Work , The scope of work performed for this study included the following: 1. Observation of a natural lot, : 2. Excavation of exploration trenches into the subject site to observe the existing soil conditions and recover samples. : 3. Laboratory testing, and; , 4. Preparation of this report including conclusions and recommendations pertinent to the proposed construction. \ . . IMr. Phil Lewis, East Vallejo Road :Project No; 99128-1 Page: 2 !Site Description IThe site is rectangular in shape, fronting 200 feet along the west side of Ynez Road and 200 feet lalong the south side of East Vallejo Road. The site currenUy flat and genUy sloping to the north west :comer at about 2 to 4 percent. PresenUy, the site is covered with a nominal growth of weeds and !grasses that were recenUy cut. No visible signs of erosion were noted. IField Work :Field work on the site consisted of observation a excavation made by backhoe for the purpose of Irecovering samples of representative earth materials for laboratory testing. The results of these tests iare contained in the attached Appendix A. Additionally, a reconnaissance of the nearby area was :conducted in order to obtain information pertinent to the site. :Observation and testing of the excavation indicated that the existing materials were of moderate to 'high: density in place with no visible pores, and is dry at the surface. Observation of the earth materials indicates a thin mantle of top soil, transitioning quickly to loose alluvial soils to a depth of iapproximately 4 to 5 feet. The materials consist of an alluvium in various stages of weathering. The backhoe was able to excavate to a depth of 14.5 feet below the ground surface with IitUe difficulty. The alluvium is noted to be loose and porous to a depth of 4 to 5 feet then becomes moist and moderately dense to the extent of the trench. ,Laboratory Testing The maximum dry density and optimum moisture content of the soil was determined in accordance with ASTM test designation D 1557-82. The expansion index testing should be conducted on a representative sample at the completion of rough grading in order to determine the expansion potential of the near surface soils in the vidnity of proposed foundations. The expansion index test should be conducted in accordance with USC 29-2. W. C. HOBBS, CONSULTING ENGINEER 2.- ~ I. . ,Mr. Phil Lewis, East Vallejo Road :Project No: 99128-1 Page: 3 CONCLUSIONS AND RECOMMENDATIONS : Conclusions I The development of the site for single or multi-story residential construction is both feasible and safe 'from a geotechnical standpoint provided that the recommendations contained herein are I implemented during design and construction. , 1: The site is essentially untouched, graded only at the westem and southem edges for roadway ! slopes and construction. ; 2: The soil is observed to be dense in place with the exception of the upper 1 foot. : 3:0bservation, classification, indicate that the near surface soils have a low to moderate expansion I potential. I Recommendations , The recommendations contained herein are contingent upon W. C. Hobbs, Consulting Engineer or I his assigns providing the services listed in the Construction section in order to confirm design I assumptions and review the field conditions of any excavations for possible anisotropic properties. , If observation indicates thatthe conditions are different than those indicated in this report, additional, , or modifications to the, recommendations may become necessary. Site Grading In order to provide proper support for building foundations, remedial grading will be required. Proposed grading consists of creating a driveway, pad and foundation areas and or the balance placement of fills on the site for a pad area in the vidnity of the proposed residence and driveway. All grading and retaining wall backfills should be placed in accordance with minimum standards presented a the back of this report, Appendix B, Standard Specifications for Earthwork Construction. Remedial grading shall consist of the removal of the upper 4 to 5 feet of alluvial soils in the building area. This removal area should extend an equal distance away from the lowest outside edge of the foundations as the final thickness of fill in the proposed area, or a minimum of 5 feet, whichever is the greater. Final determination for the depth of excavation shall be made in the field during grading operations. It is possible that additional excavations may result in more or less excavation in the building area. W. C. HOBBS, CONSULTING ENGINEER ;?J . . 'Mr. Phil Lewis, East Vallejo Road :Project No: 99128-1 Page: 4 : Recommendations, continued iBearing Value and Footing Geometry :A safe allowable bearing value forfoundations embedded into native bedrock materials or properly :compacted fill is 2000 pst This value may be increased at the rate of 1 00 psf per foot of depth and 1100 psf per foot of width over the minimums, but should not exceed 2500 pst Continuous footings Ishould have a minimum width of 12 inches and depth of 18 inches and conform to the minimum :criteria of the UBC for single and or multistory construction for moderately expansive soils. The use lof: isolated column footings is not discouraged, however, where utilized, should have a minimum :embedment of 18 inches below lowest soil grade. The minimum distance of the bottom of footings :on the outside edge and the native slope face is 8 feet. !Settlement The' bearing value recommended above reflects a total setUement of 0.5" and a differential isetUement of 0.5". Most of this settlement is expected to occur during construction and as the loads me being applied. :Concrete Slabs !A11 concrete slabs on grade should be 4 inches thick. They should be underlain by 2 inches of sand .or. gravel. Areas that are to be carpeted or tiled, or where the intrusion of moisture is objectionable, should be underlain by 6 mil visqueen properly protected from puncture with an additional 1 inch of sand over it. This arrangement of materials would result in a profile downward of concrete, 1 inch .of sand, 6 mil visqueen, 2 inches of sand and subgrade soil. Contractors should be advise that when pouring during hot or windy weather conditions, they should provide large slabs with suffidently deep weakened plane joints to inhibit the development of irregular or unsightly cracks. Also, 4 inch thick slabs should be jointed in panels not exceeding 12 feet in both directions to augment proper crack 'direction and development. :Reinforcement :Continuous footings should be reinforced with a minimum of one number 4 steel bar placed at the top and one at the bottom. Slabs should be reinforced with a minimum of number 3 steel bars placed at the center of thickness at 18-inch centers both ways or welded wire fabric equivalent to 10x10 10/10 may be used. It is understood that the sectional values for the two schedules are different, and is .of no design concem. The steel bars have been proven to have a better performance history and selection is up to the builder. Additional requirements may be imposed by the structural engineering design. W. C. HOBBS, CONSULTING ENGINEER A I. . ,Mr. Phil Lewis, East Vallejo Road :Project No: 99128-1 Page: 5 iRecommendations, continued IRetaining Walls 'Retaining walls should be designed to resist the active pressures summarized in the following table. IThe active pressure is normally calculated from the lowermost portion of the footing to the highest ,ground surface atthe back of the wall. The active pressures indicated in the table are equivalentfluid :densities. Walls that are not free to rotate or that are braced at the top should use active pressures Ithat are 50% greater than those indicated in the table. RETAINING WALL DESIGN PRESSURES Slooo of adiacent qround Active Pressure Passive Pressure 2:1 30 pcf 40 pcf 300 pcf 200 pcf LEVEL IThese pressures are for retaining walls backfilled with noncohesive, granular materials and provided Iwith drainage devices such as weep holes or subdrains to prevent the build-up of hydrostatic :pressures beyond the design values. It is imperative that all retaining wall backfills be compacted to la minimum of 90 percent relative compaction in order to achieve their design strength. Failure to :provide proper drainage and minimum compaction may resultin pressures against the wall that will :exceed the design values indicated above. Surface waters should be directed away from retaining Iwall backfill areas so as not to intrude into the backfill materials. lLateral Loads IThe bearing valtle of the soil may be increased by one third for short duration loading (wind, iseismic). Lateral loads may be resisted by passive forces developed along the sides of concrete ifootings or by friction along the bottom of concrete footings. The value of the passive resistance for ,level ground may be computed using an equivalent fluid density of 300 pcf for level ground. The !total force should not exceed 3000 psf. A coeffident of friction of .40 may be used for the horizontal lsoiVconcrete interface for resistance of lateral forces. If friction and passive forces are combined, ithen the passive values should be reduced by one third. W. C. HOBBS, CONSULTING ENGINEER 5' '. . ,Mr. Phil Lewis, East Vallejo Road :Project No: 99128-1 Page: 6 :Recommendations, continued IFine Grading : Fine grading of areas outside of the residence should be accomplished such that positive drainage iexists away from all footings. Run-off should be conducted off the property in a non erosive manner ,toward approved drainage devices at the street or the rear of the property per approved plans. : Construction !Asoil engineer should be present during the excavation of the foundations, as well as earthwork : construction, to test and or confirm the conditions encountered during this study. It is recommended ,to have the foundation excavations observed by a soil engineer prior the placement of construction 'materials in them as consequential changes and differences may exist throughout the earth 'materials on the site. It may be possible that certain excavations may have to be deepened slighUy 1 if earth materials are found to be loose or weak. :Grading PlanlReview I the grading plan should be reviewed prior to the grading to verify that the recommendations of this 'report are implemented for remedial grading and to assist in verifying extent and depth of iexcavations based on actual building placement and elevation with respect to existing ground i surface. This review is additional and beyond the scope of this report. W. C. HOBBS, CONSULTING ENGINEER Cp '. . 'Mr. Phil Lewis, East Vallejo Road : Project No; 99128-1 Page: 7 CLOSURE IThis evaluation was performed in accordance with generally accepted engineering practices. The : conclusions and recommendations contained in this report were based on the data available and the I interpretation of such data as dictated by our experience and background. Hence, our conclusions i and recommendations are professional opinions; therefore, no other warranty is offered or implied. ITheopportunity to be of service is appreciated. Should questions or comments arise pertaining to Ithis document, or if we may be of further service, please do not hesitate to call our office. ; Respectfully Submitted, ,W. C. HOBBS, CONSULTING ENGINEER : Bill Hobbs, RCE42265 : Civil Engineer : Distribution: I Attachments: Addressee (4) Appendix A - Summary of Laboratory and Field Test Results Appendix B - General Earthwork and Grading Spedfications W. C. HOBBS. CONSULTING ENGINEER \ I. APPENDIX A SUMMARY OF TEST RESULTS . W. C. HOBBS, CONSULTING ENGINEER ~ I. . APPENDIX A SUMMARY OF MAXIMUM DENSITY TEST RESULTS Curve Letter Soil Descriotion Maximum Optimum Density oct Moisture % A Silty Clayey SAND, fine to crs. wi gravel, Gray (SM-SC) 126.4 10.8 Maximum density and optimum moisture determined in accordance with test method ASTM D 1557-78. W. C. HOBBS, CONSULTING ENGINEER ~ I. . APPENDIX B GENERAL EARTHWORK AND GRADING SPECIFICATIONS W. C. HOBBS, CONSULTING ENGINEER \0 :. . GENERAL EARTHWORK AND GRADING SPECIFICATIONS 1.0 :GENERAL INTENT These specifications present general procedures and requirements for grading and earthworK as shown on the approved grading plans, incl~dingiPreparation of areas to be filled, placement offill. installation of subdrains, and excavations. The recommendations contained in the geotechnical report are a part of the earthworK and grading specifications and shall supersede the provisions contained hereinafter in the case of conflict Evaluations performed by the consultant during the course ofgrading may resuti in new recommendations of the geotechnical report. 2.0 EARTHWORK OBSERVATION AND TESTING Prior to the commencement of grading, a qualified geotechnical consultant (soils engineer and engineering geologist, and their rep~sentatives) shall be employed for the purpose of observing earthworK and testing the fills for conformance with the recommendations of the geotechnical report and: these specifications. It will be necessary that the consultant provide adequate testing and observation so that he may determine that the worK was aocomplished as specified. It shall be the responsibility of the contractor to assist the consultant and keep him apprized of worK schedules and changes so that,he may schedule his personnel aocordingly. It shall be the sole responsibility of the contractor to provide adequate equipment and methods to aocomplish the worK in aocordance with applicable grading codes or agency ordinances, these specifications and the approved grading plans. If in the opinion of the consultant, unsatisfactory conditions, such as questionable soil. poor moisture condition, inadequate compaction. adverse weather, etc., are resuiting in a quality.of ,worK less than required in these specifications, the consultant will be empowered to reject the worK and recommend that construction be topped until the conditions are rectified. Maximum dry density tests used to determine the degree of compaction will be performed in aocordance with the American Society ofT esting andlMaterials tests method ASTM 0 1557-78. 3.0 PREPARATION :OF AREAS TO BE FILLED 3.1 Clearing and Grubbing: All brush, vegetation and debris shall be removed or piled and otherwise disposed of. 3.2 Processing: The existing ground which is determined to be satisfactory for support offill shall be scarified to a minimum depth of6 inches. Existing ground which is not satisfactory shall be over excavated as specified in the following section. Scarification shall continue until the soils are broken down and free of large day lumps or clods and until the working surface is reasonably unifoml and free of uneven features which would inhibit uniform compaction. 3.3 Overexcavation: Soft. dry. spongy, highly fractured or otherwise unsuitable ground, extending to such a depth that the surface processing cannot adequately improve the condition, shall be over excavated down to firm ground. approved by the consultant. 3.4 Moisture Conditioning: Over excavated and processed soils shall be watered, dried-back, blended, and/or mixed, as required to attain a uniform moisture content near optimum. 3.5 Recompaction: Over excavated and processed soils which have been properly mixed and moisture- conditioned shall be recompacted to a ,minimum relative compaction of 00 percent. 3.6 Benching: Where fills are to be placed on ground with siopes sleeper than 5: 1 (horizontal to vertical units), the ground shall be stepped or benched.' The lowest bench shall be a minimum of 15 feet wide. shall be at least 2 feet deep, shall expose firm material, and shall be approved by the consultant. Other benches shall be excavated in firm material for a minimum width of 4 feet. Ground sloping flattar than 5 : 1 shall be benched or otherwise over excavated when considered necessary by the consultant. 3.7 Approval: All areas to receive fill, including processed areas, removal areas and toe-of-fill benches shall be approved by the consultant prior to fill placement. W. C. HOBBS, CONSULTING ENGINEER \\ . . 4.0 :FILL MATERIAL 4.1 General: Material to be placed as fill shall be free of organic matter and other deleterious substances. and shall be approved by the consultant Soils of poor gradation, expansion, or strength characteristics shall be placed in areas designated by consultant or shall be mixed with other soils to serve as satisfactory fill material. 4.2 Oversize: Oversize material defined as rock, or other irreducible material with a maximum dimension greater than 12 inches, shall not be buried or placed in fills, unless the location, materials. and disposal methods are specifically approved by the consultant. Oversize disposal operations shall be such that nesting of oversize material does not occur, and such that the oversize material is completely surrounded by compacted or densified fill. Oversize material shall not be placed within 10 feet vertically of finish grade or within the range offuture utilities or underground construction, unless specifically approved by the consultant 4.31Import: If importing of fill material is required for grading, the import material shall meet the requirements of Section 4. 1. 5.0 1 FILL PLACEMENT AND COMPACTION 5.1 Fill Lifts: Approved fill material shall be placed in areas prepared to receive fill in near-horizontallayers not exceeding 6 inches in compacted thickness. The consultant may approve thicker lifts if testing indicates the gradin9 procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer shall be spread evenly and shall be thoroughly mixed during spreading to attain uniformity of material and moisture in each layer. 52 Fill Moisture: Fill layers at a moisture content less than optimum shall be watered and mixed, and wet fill layers shall be aerated by scarification or shall be blended with drier material. Moisture-conditioning and mixing of fill layers shall continue until the fill material is at a uniform moisture content or near optimum. 5.3 COn;Jpaction of Fill: After each layer has been evenly spread. moisture conditioned, and mixed, ~ shall be uniformly compacted to not less than 90 percent of maximum dry density. Compaction equipment shall be adequately sized and shall be either specifically designed for soil compaction or of proven reliability. to efficiently achieve the specified degree of compaction. 5.4 Fill Slopes: Compaction of slopes shall be aocomplished, in addition to normal compacting procedures, by backfilling of slopes with sheepsfootrollers atfrequent increments of2to 3 feet in fill elevation gain. orbyother methods producing satisfactory results. Atthe completion of grading; the relative compaction of the slope out to the slope face shall be at least 90 percent. 5.5 Compaction Testing: Field tests to check the ill moisture and degree of compaction will be performed by the consultant. The location and frequency of tests shall be at the consultanfs discretion. In general, the tests will be taken at an interval not exceeding 2 feet in vertical rise and/or 1.000 cubic yards of embankment. 6.0 SUBDRAlN INSTALLATION Subdrain systems. if required, shall be installed in approved ground to conform to the approximate alignment and details shown on the plans orherein. The subdrain location or materials shall not be changed or modified without the approval of the consultant. The consultant, however, may recommend and upon approval, direct changes in subdrain line. grade or material. All subdrains should be surveyed for line and grade after installation. and sufficient time shall be allowed for the surveys, prior to commencement of filling over the subdrains. W. C. HOBBS, CONSULTING ENGINEER \-z... . . 7.0 EXCAVATION Excavation and cut slopes will: be examined during grading. If directed by the consultan~ further excavation or over excavation and refilling of Cl:Jt areas shall be performed, and/or remedial grading of cut slopes shall be performed. Where fill-over -art slopes are to be graded, unless otherwise approved, the cut portion of the slope shall made and approved by the consultant prior to placement of materials for construction of the fill portion of the slope. 8.0 TRENCH BACKFILL 8.1 Supervision: Trench excavations for the utility pipes shall be backfilled under engineering supervision. 8.2 Pipe'Zone: After the utility pipe has been laid, the space under and around the pipe shall be backfilled with dean sand or approved grar,lular soil to a depth of at least one foot over the top of the pipe. The sand backfill shall be uniformly jetted into place before the controlled backfill is placed over the sand. 8.3 Fill Placement: The onsite materials, or other soils approved by the engineer. shall be watered and mixed as necessary prior to placement in lifts over the sand backfill. 8.4 Compaction: The controlled backfill shall be compacted to at least 90 percent of the maximum laboratory density as determined by the ASTM compaction method described above. 8.5 Observation and Testing: Field density tests and inspection of the backfill procedures shall be made by the soil engineer during backfilling too see that the proper moisture content and uniform compaction is being maintained. The contractor shall provide test holes and exploratory pits ,as required by the soil engineer to enable sampling and testing. W. C. HOBBS, CONSULTING ENGINEER \7 . . " c I V' f'" ':l> .... '" 1_____- ~ 'i/JCz. ~~ ..; r, "'I - g . r.: C! :;:1 ... ~ ':: ~i ! ~, ,~. "I "- c -- , J I __.~ ~' .~ , ' , , -~ . '5. , I , , -...f.. 't',-Q ..j.... 0., ~/< " " '1>" r".. ,- ~ " ", i \ , , \ \ " .' , \ \ \ \ , , I , , , , , \. \ r \ ~;..>.. \ .,....;-... '. \ '1\ h ~!\ "'i. \ .' , , , \ .' .' , .' \ , , .' " \ .' , '. .' " " .' , .' .' , " . o ~ ;. 2 ':. i- ~ -.,- 8" "i"~ r" ::CORD ' . ?'r /.. '2\~ ,// _ .~_ ..1....-. -L--_...-L-~\;' /// . ------------,--\/j' SITE PL.fl , , \ , \ , , , \ \ ~ ~ OJ 1PaJC.H1 '-../ @ .' , , , .' , " CD .' , " , " "'-, - '. " """,(jj "'>Q; "" '...... , '. .' .' .' , .......... ---_.--.-- - .' , .' .' , .-- - - - - "".. ... "':~ 1: , ,~ /:," ~ ~" . ~. ::l .0 il'!~ 1..;,.:. j ! , I ""'1 I , r , , .., :::! :1 .., ::> II: I~ j " <l: ," ::> j-. " 'I " r i 1 j iJ }'{ - - - - ... I , / " " i-- . -- . ~ / . , ' r ;1I I / .... fU ~'lS'''~.~ . n":. -"':':~'v----=::i'ii~.-":':-".;'€.i.x~;~.tJ Pl.-A~ 1 ~l-\ LOCAlloN ~ PN: Q(l\'2.e-\ t::>~~ ~G. 30, tm " <>'i " ~ CI ~ .., l.J .. lJo~) _.1,,,,,. 1 I I , 'ICe,! J- ", II: .... f r ~ . \A;. ~