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HomeMy WebLinkAboutTract Map 3929 Lot 171 Preliminary Soils ~ PRELIMINARY SOIL INVESTIGATION for Lot 171; TR 3929 APN: 921-111-003 28870 Via Norte Temecula, California November 3, 1999 Prepared for: Mr. Gerald Throckmorton 28870 Via Norte Temecula, California 92591 Prepared by: Gunvant Thakkar, P.E. 45712 Classic Way Temecula, California 92592 (909) 676-7541 \ GUNVANT THAKKAR, PROFESSIONAL ENGINEER 45712 Classic Way, Temecula, California 92592 (909)676-7541 November 3, 1999 Mr. Gerald Throckmorton 28870 Via Norte Temecula, California 92591 Subject: Preliminary Soil Investigation Lot 171; TR 3929 APN: 921-111-003 Temecula, California Dear Mr. Throckmorton: In accordance with your request and authorization, this report presents the results :of our soils investigation of the subject property located at 28870 Via Norte in the Meadowview tract, Temecula, California (see Site Location Map Figure 1). The purpose of the study was to evaluate the existing soil condition on the subject property relative to the proposed development. 1. Site Description The property is located at 28870 Via Norte in the Meadowview tract, Temecula, Riverside County, California, and consists of approximately 0.57 (+/-) acres. The lot slopes from southeast to the northwest approximately 20' overall. There is an existing house with attached garage as well as a detached garage, and associated driveways and landscaping on the property. 2. Proposed development It is our understanding that there will be a room addition added between the house and the detached garage. The site is rolling hills. The highest point on the property is the southerly portion. The site is mostly 2. accessible. Building loads are assumed to be typical for residential structures. 3. Field Studies The field studies conducted during our evaluation of the property consisted of the following: a. review of available geotechnical data in our files pertaining to the site. b. field reconnaissance by a soils engineer. c. laboratory testing of selected representative soil samples. d. preparation of this report presenting our findings, conclusions, and recommendations. 4. Subsurface Investiaation Laboratory Testina A total of one sample was taken in order to determine the conditions of the near-surface natural material. The sample was logged, in-place moisture and density of the exposed materials was recorded, and representative bulk and relatively undisturbed samples were collected for laboratory testing. 5. Laboratory Testina a. Soil Classification Soils were classified visually according to the unified soils classification system. The soils classifications are shown on the sample logs (Appendix A). b. Soils Density The field moisture content and dry unit weights were determined for each undisturbed sample of the soils encountered in the sample. The dry unit weight was determined in pound per cubic foot and the field moisture content was determined as a percentage of the dry unit weight. The results of this test are shown on the sample logs (Appendix A). .3 6. General Site Gradina All grading shall be performed in accordance with the General Earthwork and Grading Specifications (Enclosure C), and the specifications of the local agencies should be implemented into the design of the proposed site. Prior to grading, deleterious trash and vegetation should be removed and hauled off-site. All areas prepared and approved to receive fill should be scarified, moisture conditioned, and compacted to a minimum of 90 percent relative compaction prior to fill placement. 7. Ground Water No groundwater or evidence of seepage was encountered within the sample area at the time and location of sample taking. However, other conditions may be there that would effect the entire proposed project and final plans and specifications. 8. Conclusion and Recommendation a. General 1. Based on our field exploration, laboratory testing, and our soil engineering analysis, it is our opinion that the project site is suited for the proposed development from a soils engineering viewpoint. The recommendation presented below should be incorporated in the design, grading, and construction considerations. 2. Soils engineering and compaction services should be provided during grading to aid the contractor in removing unsuitable soils and in his effort to compact the fill. 3. Ground water is not expected to be a factor in the development of the site. However, caving and sloughing may be anticipated to be a factor in all subsurface excavation and trenching. 4. At the time of preparation of this report, the proposed finished pad grades, location of any structures, type of structures and loadings were all of a preliminary planning nature. 5. General earthwork and grading guidelines are provided at the end of this report as Appendix C. ~ b. Demolition/Grubbing 1. Existing shrubs, and any miscellaneous construction materials and debris should be removed from the site. 2. Any previous foundation, cesspools, septic tanks, leach fields, or other subsurface structures, uncovered during the recommended removal should be observed by the soils engineer so that appropriate remedial recommendations can be provided. 3. Cavities or loose soils (including all trenches) remaining after demolition and site clearance should be cleaned out, inspected by the soils engineer, processed and replaced with a fill that has been moisture conditioned to at least optimum moisture content and compacted to at least 90 % of the laboratory standards. c. Fill placement 1. Fill material should be brought to at least optimum moisture, placed in thin 6 to 8 inch lifts, and mechanically compacted to obtain minimum relative compaction of 90 percent of the laboratory standard. 2. Fill material should be cleansed of major vegetation and debris prior to placement. 3. Any oversized rock material greater than 10 inches in diameter should be placed under the recommendations and supervision of this soils engineer. d. General Foundation Criteria The proposed structure may be supported on conventional spread, or continuous wall footings, provided that they are at least 12 inches wide, and 12 inches below the final approved grade with one # 4 rebar at the top and bottom or as designed by the structural engineer. Footings may be designed for a maximum bearing pressure of 1500 psf. A friction coefficient for concrete on natural and compacted soils of 0.36 may be employed. The effects of seismic shaking can be mitigated through consideration of the parameters presented above and by design in accordance with the latest Uniform Building Code and the Structural Engineers Association. 5" The allowable bearing pressure may be increased by one-third when considering loadings of short duration such as wind or seismic forces. This foundation criteria is considered minimum and may be superseded by more restrictive requirements of the structural engineers, architects, or governing agency. e. Concrete Slabs on Grade Sufficient fine grained materials exist within near surface earth materials to possibly create moisture problems. Therefore, we recommend that a moisture barrier be placed under any concrete slabs that might receive a moisture-sensitive floor covering. This moisture barrier should consist of a 10-mil polyethylene vapor barrier sandwiched between a one inch layer of sand, top and bottom, to prevent puncture of the barrier and enhance curing of the concrete. Nominal reinforcement of the slabs with light six inch by six inch, 10 gauge/10 gauge welded wire fabric is advisable. Slabs should be designed for any special loads, such as construction crane loads, if warranted. Large slabs should have crack control joints on 10 foot centers and small slabs should have them on five foot centers. f. Expansive Soils Based on visual observations and field classifications, there does not appear to be any soils at the surface which appear highly expansive; however, if fill materials are imported to the site, it is recommended that expansion testing be performed upon the completion of grading to evaluate any expansion potentials. g. Earthwork Shrinkage and Subsidence When the existing less dense materials is regraded to compacted fill standards, earthwork shrinkage should be estimated to range between 9 and 17 percent (based on an average of 92 percent relative compaction), for a total 4 foot over-excavation below existing grade. This variation is due to the large difference in in- place densities obtained during our soil sampling. It should be noted that these estimates are exclusive of any losses due to any possible buried substructures (Le. septic tanks, pipes, etc.) or localized fill pockets. Earthwork operations should cause only a nominal subsidence of approximately 0.1 foot or less. ~ h. Lateral Loads Lateral loads in the near surface soils are: Active 35 pounds per square foot per foot of soil depth (psf/ft) 64 psflft 250psf/ft - wood shoring 350psf/ft - concrete footings At Rest Passive Active means movement of the structure away from the soil. At rest, means the structure does not move relative to the soil (such as a loading dock or building wall). Passive means the structure moves into the soil. The coefficient of friction between the bottom of the footings and the native soil may be taken as 0.35. L Trench Stability The near surface soil is a depth of 6 feet may not stand vertically for more than several hours when excavated as tension cracks or joints may be locally found in the soils associated with past seismic activity from nearby major faults. Trenches in excess of 5 feet in depth should have the sides laid back at 1: 1 or shored in accordance with OSHA requirements. j. General Site Grading 1. General All grading should be performed in accordance with the standard grading and earthwork specifications outlined in Appendix C, or unless otherwise modified in the text of this report. 2. Clearing and Grubbing The site should be clear of any vegetation and hauled off site. Any and all of the debris, and all the deleterious and oversized material should be carefully removed and also hauled off site. The soil should be over-excavated as described below. 1 3. Site Preparation The site will require removal of loose natural soils and fill materials (if found), based on field observation and laboratory testing. On all buildings that may have columns extending into the native materials, no preparations of soil is necessary when in place densities indicate 85 percent relative compaction beneath the footings providing all foundations are in natural soils. 4. Placement of Compacted Fill Compacted fill is defined as that material which will be added to the site and/or replaced in the areas of removal, due to relatively low density soils. All fill should be compacted to a minimum of 90 percent based upon maximum density obtained in accordance with ASTM D1557-78 procedure. The area to be filled will be prepared in accordance with preceding section 3. 5. Review of Grading Plan and Specifications We recommend that the soils engineer have the opportunity to review the final grading plan and the specifications to ensure that they include the item of the soil report for the benefit of the owner and the contractor, in particular, to verify the over-excavation depth and elevation, if proposed grade elevations are different from that of existing ground surface present at the time of our field investigations. 6. Pre-Job Conference Prior to the commencement of grading, a pre-job conference should be held with the representative of the owner, developer, contractor, architect, and/or engineer, and soil engineer, in attendance. The purpose of this meeting will be to clarify any questions relating to the intent of the grading recommendations and to verify that the project specifications comply with the recommendations of this report. 7. Testing and Inspection During grading, density testing should be performed by a representative of the soils engineer in order to determine the ~ degree of compaction being obtained. Where testing indicates insufficient density, additional compactive efforts shall be applied with the adjustment of moisture content, where necessary, until at least 90 percent relative compaction is obtained. The subgrade of the over- excavations and the footing excavations should be inspected and improved by us prior to placement of fill and/or concrete. The maximum dry density shall be determined in accordance with ASTM D1557-78 procedure. 8. Summary All grading should, at a minimum, follow the "Standard Grading and Earthwork Specifications" as outlined in Appendix C, unless otherwise modified in the text of this report. The recommendations of this report are based on the assumptions that all footings will be founded in properly compacted fill soil or natural dense soil as approved by the soils engineer. All footing excavations should be inspected prior to the placement of concrete in order to verify that footings are founded on satisfactory soil and are free of loose and disturbed materials. All gradings and fill placement should be performed under the testing and inspection of a representative of the soils engineer. 9. Investigation Limits The materials encountered on the project site and utilized in the laboratory are believed representative of the total area; however, soils materials may vary in characteristics between test excavations. Since our investigation is based upon the site materials observed, selective laboratory testing, and engineering analysis, the conclusions and recommendations are professional opinions. It is possible that variations in soil conditions could exist beyond the points explored in this investigation. Also, changes in the ground water condition could occur sometime in the near future due to variations in temperature, regional rainfall, and other factors. Should conditions be encountered during grading that appear to be different than those indicated by this report, the soils engineer should be notified. These opinions have been derived in accordance with current standards of practice and no warranties are expressed or implied. ~ We sincerely appreciate this opportunity to be of service. If you have any questions concerning this report, please contact us at 909/676-7541. Very truly yours, .~~'~ c:liA__~ Gunva'ntThakkar;P.E. I RCE'52856 . ;-O~ j EXP;12t3'~lg~!V itA:,: -./;.." .~- v-z-'-"> . -. .';". \0 Enclosures:Plate1: Site location map Plate 2: Sample location map Appendix A: Sample logs Appendix B: Laboratory test data Appendix C: Standard grading and earthwork specs. \\ I ~ I-/Sti.1 I \!Ii ~I I DATE: 1I'~-'3~ I~ !~ l~ .~ . ~.'P eo:rli c r ., SITtE S(J LaN 1/ (AI A Y RAP/aHa elJ.LI RJt2H',4 RoAo SITE LOCATION PLAN PLATE: I \z.. /V.:J~S1T '3TN~ f. 7: :1..:l. J - """ \1\ . l-l ~ :~ ,>.">~' ~ ;~ 'l l j I \ , 1 """- I \ l \ \ I I I I , i \ I \ \ \ \ 1 1 I I I , . l'. __ ,'>> .... .... ",ii?[A;~ . .' ", ? 'I. "'..- OJ.,:///// ~ / f - : '/ , 12,3 05 I If.:" 4 50 ---- - ~ - '- :' .3 -Ii DATE: I/-'J-~!J SAMPLE LOCATION PLAN LEGEND . APPROXIMATE SAM. LOCATION \?> I PLATE: 2 Appendix A Exploratory trench logs \A; " PtOleqt Hatn. ... f't1O/O.f; t flun\b.y ,'7/lJeOCk'h1olf 77J1'Y . h... "01 '_ 4/5 a....".." 1".110" No. ..fj e:....tpon."t , 1 I~ oeSQOIPTtOH . i- I.. I oeOTECHNICAI. .. " i ! a i t."99~ ey . " '<iT -.!.t.i-'1Y 1 .. t I Dale .i f _II ! ......ed 11>, ,(],;- ... ~ II ~ , - , LT. JiIlO~ - S'I'THO!,... - , GO "'" ~ , ~ ('l.." ~ Ol - "I I .. . 5- 0' . .. .~ '- . ,. - . . . ., , - '0- .. '. .. .. 1$- . .- - GRADwj.-, \.OG frend- $cale; "..5" . - . Tost SymbOls - - - D.. .Vl,. .5....14 . . It.. Sh"t a.",." " . . . " : . . ac. tSMoe c~. , . I '- T 1 1 . . . . . . - . MO.. ~ 0.0_''''' - - OS. a,...... S.I. . - 5e - a.... PflCli......-.u - --'.- - iiI - C.O.....hf" ....... .. n8.. ....mQ...~ s....- - - .. ... .. - . 0 . . , I I . . . . , , , . . !fru ' 'TT , .0;:..; "r-:' TERRA - . . 1) ~ GF.OSCIENCES - _..,.~. . r ".0. &-. ,(WI" - - h.t,... le.,t>. ("A ,)'\IjJ - - \~ Appendix B Laboratory test data \~ Location A Maximum Dry Density Test Results Soil Descriotion Silty sand Light Brown Maximum Dry Density locO 128.5 Optimum Moisture 9.8 % \\ Appendix C Standard Grading and Earthwork Specs. \'f; STANDARD GRADING AND EARTHWORK SPECIFICATIONS These specifications present our recommendations for grading and earthwork. No deviation from these specifications should be permitted, unless where specifically superseded in the geotechnical report of the project or by written communications signed by the geotechnical consultant. Evaluation performed by the consultant during the course of grading may result in subsequent recommendations which could supersede these specifications or the recommendations of the geotechnical report. 1.0 General 1.1 The geotechnical consultant is the owners or developers representative on the project. For the purpose of these specifications, observations by the geotechnical consultant include observations by the soils engineer, geotechnical engineer, engineering geologist, and those performed by persons employed by, and responsible to the geotechnical consultant. 1.2 All clearing, site preparations, or earthwork performed on the project shall be conducted and directed by the contractor under the supervision of the geotechnical consultant. 1.3 The contractor should be responsible for the safety of the project and the satisfactory completion of all grading. During grading, the contractor should remain accessible. 1.4 Prior to commencement of grading, the geotechnical consultant shall be employed for the purpose of providing field, laboratory, and office services for conformance with the recommendations of the geotechnical report and these specifications. It will be necessary that the geotechnical consultant provide adequate testing and observations so that he may determine that the work was accomplished as specified. It shall be the responsibility of the contractor to assist the geotechnical consultant and keep him apprised of work schedule and changes so that he may schedule his personnel accordingly. 1.5 It should be the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the work in accordance with applicable grading codes or agency ordinance, these specifications, and the approved grading plans. If, in the opinion of the geotechnical consultant, unsatisfactory conditions, such as questionable soil, poor moisture condition, inadequate compaction, adverse weather, etc. are resulting in a quality of work less than required in these specifications, the geotechnical \~ consultant will be empowered to reject the work and recommend that construction be stopped until the conditions are rectified. 1.6 It is the contractor's responsibility to provide access to the geotechnical consultant for the testing and/or grading observation purposes. This may require excavation of the test pits and/or the relocation of grading equipment. 1.7 A final report shall be issued by the geotechnical consultant attesting to the contractor's conformance with these specifications. 2.0 Site PreDaration 2.1 All vegetation and deleterious material shall be disposed of off site. This removal shall be observed by geotechnical consultant and concluded prior to fill placement. 2.2 Soil, alluvium, or bedrock materials determined by the geotechnical consultant as being unsuitable for placement in compacted fills shall be removed by the site or used in landscape areas as determined by the geotechnical consultant. Any material incorporated as a part of compacted fill must be approved by the geotechnical consultant prior to fill placement. 2.3 After the ground surface to receive fill has been cleared, it shall be scarified, disked, or bladed by the contractor until it is uniform and free from roots, hollows, hummocks, or other uneven features which may prevent uniform compaction. The scarified ground surface shall then be brought to optimum moisture, mixed as required, and compacted as speCified. If the scarified zone is greater than 12 inches in depth, the excess shall be removed and placed in lifts restricted to 6 inches. Prior to placing fill, the ground surface to receive fill shall be observed, tested, and approved by the geotechnical consultant. 2.4 Any underground structures or cavities, such as cesspools, cisterns, mining shaft, tunnels, septic tanks, wells, pipelines, or others, are to be removed or treated in the manner prescribed by the geotechnical consultant. 2.5 In cut fill transition lots and where cut lots are partially in soil, colluvium, or unweathered bedrock materials, in order to provide uniform bearing conditions, the bedrock portion of the lot, extending 1.P a minimum of 5 feet outside of building line, shall be over- excavated a minimum of 3 feet and replaced with compacted fill. 3.0 Compacted Fills 3.1 Materials to be placed as fill shall be free of organic matter and other deleterious substances, and shall be approved by the geotechnical consultant. The soils of poor gradation, expansion, or strength characteristic shall be placed in areas designated by the geotechnical consultant or shall be mixed with other soils to serve as satisfactory fill materials, as directed by the geotechnical consultant. 3.2 Rock fragments less than 6 inches in diameter may be utilized in the fill, provided: a. They are not placed in concentrated pockets. b. There is sufficient percentage of fine grained materials to surround the rocks. C. The distribution of rocks is supervised by the geotechnical consultant. 3.3 Rocks greater than 6 inches in diameter shall be taken off site or placed in accordance with the recommendation of the geotechnical consultant in areas designated as suitable for rock disposal. 3.4 Materials that are spongy, subject to decay, or otherwise unsuitable, should not be used in the compacted fill. 3.5 Representative samples of materials to be utilized as compacted fill shall be analyzed by the laboratory of the geotechnical consultant to determine their physical properties. If any material other than that previously tested is encountered during grading, the appropriate analysis of this material shall be conducted by the geotechnical consultant as soon as possible. 3.6 Materials used in the compacting process shall be evenly spread, watered, processed, and compacted in thin lifts not to exceed 6 inches in thickness, to obtain a uniformly dense layer. The fill shall be placed and compacted on a horizontal plane unless otherwise approved by the geotechnical consultant. 2>. 3.7 If the moisture content or relative compaction varies from that required by the geotechnical consultant, the contractor shall rework the fill until it is approved by the geotechnical consultant. 3.8 Each layer shall be compacted to 90 percent of the maximum density, in compliance with the testing method specified by the controlling government agency or ASTM 1557-78, whichever applies. If compaction to a lesser percentage is authorized by the controlling governmental agency because of specific land use of expansive soil condition, the area to receive fill compacted to less than 90 percent shall either be delineated on the grading plan or appropriate reference made to the area in the geotechnical report. 3.9 All fill shall be keyed and benched through all topsoil, colluvium, alluvium, or creep materials, into sound bedrock or firm materials where the slop receiving fill exceed a ratio of 5 horizontal to 1 vertical, in accordance with the recommendations of the geotechnical consultant. 3.10 The key for side hill fills shall be a minimum width of 15 feet within bedrock or firm materials, unless otherwise specified in the soils report. 3.11 Sub drainage devices shall be constructed in compliance with the ordinance of the controlling government agency or with the recommendations of the geotechnical consultant. 3.12 The contractor will be required to obtain a relative compaction of 90 percent out of the finished slope face of fill slopes, buttresses, and stabilization fills. This may be achieved by either overbuilding the slope and cutting back to the compacted core, by direct compaction of the slope and cutting back to compacted core, by direct compaction of the slope face with suitable equipment, or by any other procedure which produces the required compaction approved by the geotechnical consultant. 3.13 All fill slopes should be planted or protected from erosion by other methods specified in the geotechnical report. 3.14 FiII-over-cut slope shall be properly keyed through topsoils, colluvium, or creep materials into rock or firm materials, and the transition shall be stripped of all soils prior to placing fill. 2-"2.. 4.0 Cut Slooe 4.1 The geotechnical consultant shall inspect all cut slopes or vertical intervals not exceeding 10 feet. 4.2 If any conditions not anticipated in the geotechnical report, such as perched water, seepage, lenticular, or confined strata of potentially adverse nature, unfavorably-inclined bedding, joints, or fault planes encountered during grading, these conditions shall be analyzed by the engineering geologist, and recommendations shall be made to mitigate this problem. 4.3 Cut slopes that face in the same direction as prevailing drainage shall be protected from slope wash by a non-erodible interceptor swell placed at the top of the slope. 4.4 Unless otherwise specified in the geotechnical report, no cut slopes shall be excavated higher or steeper than that allowed by the ordinance of controlling governmental agencies. 4.5 Drainage terraces shall be constructed in compliance with the ordinances of controlling governmental agencies, or with the recommendations of the geotechnical consultant or engineer geologist. 5.0 Trench Backfills 5.1 Trench excavations for utility pipes shall be backfilled under the supervision of the geotechnical consultant. 5.2 After the utility pipe has been laid, the space under and around the pipe shall be backfilled with clean sand or approved granular soil to a depth of at least 1 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. 5.3 The onsite materials, or other soils approved by the geotechnical consultant, shall be water and mix as necessary prior to placement in lifts over the sand backfill. 5.4 The controlled backfill shall be compacted to at least 90 percent of the maximum laboratory density as determined by ASTM D1557-78 or the controlling governmental agency. 5.5 Fill density test and inspection of the backfill procedures shall be made by the geotechnical consultant during backfilling to see that ~ proper moisture content and uniform compaction is being maintained. The contractor shall provide test holes and exploratory pits as required by the geotechnical consultant to enable sampling and testing. 6.0 Gradina Control 6.1 Inspections of the fill placement shall be provided by the geotechnical consultant during the progress of grading. 6.2 In general, density tests should be made at intervals not exceeding 2 feet of fill height or every 500 cubic yards of fill placed. This criterion will vary, depending on the soil condition and size of the job. In any event, an adequate number of fill density tests shall be made to verify that the compaction is being achieved. 6.3 Density tests should also be made on the surface material to receive fills as required by the geotechnical consultant. 6.4 All cleanup, processed ground to receive fill, key excavations, subdrains, and rock disposals should be inspected and approved by the geotechnical consultant prior to placing any fill. It shall be the contractors responsibility to notify the geotechnical consultant when such areas are ready for inspection. 7.0 Construction Consideration 7.1 Erosion control measures, when necessary, shall be provided by the contractor during grading and prior to the completion and construction of permanent drainage control. 7.2 Upon completion of grading and termination of inspectors by the geotechnical consultant, no further filling or excavating, including that necessary for footings, foundations, large tree wells, retaining walls, or other features shall be performed without the approval of the geotechnical consultant. 7.3 Care shall be taken by the contractor during final grading to preserve any berms, drainage terraces, interceptor swells, or other devices of permanent nature on or adjacent to the property. ~~