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Home My WebLink AboutTract Map 3883 Lot 107 Prelim Soils Investigaiton I I I I I I I I I I I I I I I I I I I Page 2 ofl4 PROJECT SCOPE Explore the subsurface conditions to the depths influenced by the proposed construction. Evaluate, by laboratory test, the pertinent engineering properties of the various strata which will influence the development, including their bearing capacities, expansive characteristics and settlement potential Develop soil engineering criteria for the site grading and provide design information regarding the stability of cut/fill slopes. Determine potential construction difficulties and provide recommendations concerning these problems. Recommend an appropriate foundation system for the type of structures anticipated and develop soil engineering design criteria for the recommended design. z I I I I I I I I I I I I I I I I I I I Page 3 ofl4 THE SITE The site consists of a rectangular shaped residential lot of .55 acres located within the City ofTemecuIa. The site is located on the East side ofCarmeIita Circle. This parcel slopes moderately from the Northeast to the Southwest. The majority of the lot is covered with native scrub trees, grasses and vegetation common to the area. Large, modern single fumily residences have been developed in the surrounding area. A shallow undocumented fill traverses the lot at its midway point. A Grading Plan for the future residential pad is being prepared by Gunvant Thakkar and will be processed with the Temecula Engineering Department. Maximum cut and fill depths anticipated are in the range of 7x. Quantities show cut and fill balance of 1200 cubic yards. The proposed development will consist of a graded pad to accommodate a single family residence, and associated amenities. .3 I I I I I I I I I I I I I I I I I I I Page 4 of 14 FIELD INVESTIGATION In August 2002, our firm made a field reconnaissance of the site. Several 24" wide backhoe excavations were made on the site within or near the proposed development area. In all of the excavated pits, the soils profiles were nearly identical. From the surfuce to approximately 5' in depth the soil consists oftan silty sandy D.G.. This is underlain by a dense tan silty decomposed granite. Representative soil samples were taken from the site and laboratory testing was performed on these soil samples in order to evaluate pertinent physical characteristics so that we might make appropriate development recommendations contained later in this report. These granite soils are considered to be rippable by modern dozers although the possibility of underlying granite rock floaters that require blasting may be encountered as excavation progresses. Ground water was not encountered during our investigation and ground water is not expected to be a problem during the grading process. The predominant soils anticipated to be encountered during residential lot grading are considered to be non-expansive and no special design considerations will be necessary to compensate for expansive characteristics. i\ I I I I I I I I I I I I I I I I I I I Page 5 ofl4 LABORATORY TESTS Laboratory tests were perfurmed in accordance with generally accepted test methods of the American Society for Testing and Materials (ASTM) and other suggested procedures. The maximum dry density and optimum moisture content of the near surface soils were determined in accordance with ASTM test D1557, Method A. In addition, a direct shear test was performed on samples remolded to 90% of maximum dry density at optimum moisture content. Field moisture content and dry density were determined from representative undisturbed samples. This information was an aid to classification and permitted recognition of variations in material consistent 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 soils dry weight. Field classifications were verified in the laboratory by visual examination. The final soils classifications are in accordance with the Unified Soil Classifications System. Direct shear tests were performed to evaluate bearing potential along with maximum density testing and laboratory expansive analysis. Maximum dry density of the tan silty sandy decomposed granite layer found was determined to average 130.0 pcf at 8.2% optimum moisture content. Based upon a visual analysis I have made the conclusion that this material is non- expansive. No special design considerations will be necessary to compensate for expansive soil characteristics if construction occurs on these soil types. -s I I I I I I I I I I I I I I I I I I I Page 6 ofl4 NEAR SOURCE FACTOR A review of the "Active Fault Near-Source Zones Map" prepared by the California Department for Conservation Division of Mines and Geology indicates that there are no known mapped faults within 15 KID of the site. In conformance with Tables 16-S and 16- T of the 1997 U.B.C., the Na factor Type A is 1.0 and Type B is 1.1 and the Nv factor Type A is 1.0. and Type B is 1.3 " I I I I I I I I I I I I I I I I I I I Page 7 of14 CONCLUSIONS AND RECOMMENDATIONS The following conclusions and recommendations are based on the results of our document review, field recorlnlJi<:..,lmce and investigations, test pits, laboratory data and engineering analysis, our experience in the general vicinity of the site, and our professionaljudgrnents. The site may be utilized for the proposed development provided the recommendations of this report are carefully followed. Properly compacted native soils should adequately support the proposed structures without detrimental settlement. The recommendations presented in this report are contingent on review of final plans and specifications. It is recommended that HL Engineering & Surveying, be retained to provide continuous soil engineering services during the earthwork operations. This is to observe compliance with the design concepts, specifications, and recommendations and to allow design changes in the event subsurface conditions differ from those anticipated prior to start of construction. GEOLOGIC HAZARDS No major hazards, such as fuults or landslides, were identified to be present on, or in the immediate vicinity of, the site. GENERAL SITE PREPARATION Removal of loose, unsuitable soil or undocumented fill will be required before placement of engineered fill in all proposed fill areas. We recommend that all organic matter, oversize rock, and other deleterious materials be removed from the site. All loose or porous surfuce soils, and any fill soils not removed by the grading operation, shall be excavated and scarified as required, watered, and compacted prior to placing any additional fill. All existing trees that need to be removed to grade the site (including root systems) shall be removed from the site. , I I I I I I I I I I I I I I I I I I I Page 8 of14 Surfuce and subsurface water is not expected to be a problem during the construction of the pad embankment. The anticipated depths of surfuce soils removal and alluvial removal in the proposed driveway area and residential pad are anticipated to be approximately 3- 3Y:z feet in depth. The toe key of the proposed fill shall then be founded a minimum of2.0 feet into the formational under1ying granite. After overexcavation, the exposed surface shall be scarified to a depth of 12 inches, watered as required, and properly compacted prior to placing fill. In-situ scarification can generally treat the upper 12 inches of soil; otherwise, overexcavation will be necessary. The actual depth of the excavation and recompaction should be determined in the field by the soil engineer or his representative during grading, when the soils are exposed. All embankment shall be compacted to a minimum of 90% relative compaction and all existing ground within 7.0 feet laterally and to a depth of 1.0 foot below the bottom of foundations shall be compacted to a least 90% relative compaction. Driveway subgrade shall be compacted to at least 95% relative compaction. Rock over 12 inches in diameter is not considered acceptable as fill, and will have to be removed from the site, or incorporated with the site landscaping. Results of our field explorations indicate that all material within the proposed grading depths can be excavated with medium to heavy ripping effort with heavy-duty grading eqnipment. The efficiency of excavation is dependent upon condition of equipment and capability of the operator. There is a possibility that non-rippable rock will be encountered during the proposed grading operation. If blasting becomes necessary, a separate blasting permit will be required by the City ofTemecula' Rock over 12 inches in diameter is not considered acceptable as fill, and will have to be removed from the site, or incorporated with the site landscaping. 8 I I I I I I I I I I I I I I I I I I I Page 9 of 14 It is our recommendation that the proposed transition building pad be overexcavated to provide a uniform fill mat (a minimum thickness of 3 feet) below finish pad grade. Replacement soils should be recompacted to a minimum relative compaction of90 percent (based on ASTM 01557-78) Cut and fill slopes should be provided with appropriate surfuce drainage features and landscaped with drought tolerant, slope stabilizing vegetation as soon as possible, to ",inim;7e potential for erosion. Berms should be provided at the top of all slopes and lot drainage directed such that surfuce runoff on slope fuces is minimized. STABILITY OF FILL SLOPES AND CUT SLOPES Preliminary grading plans prepared by Gunvant Thakker, R.C.E. 52856, indicate that fill and cut/fill slopes are proposed, which may extend up to approximately 7-8 feet in height. We recommend that all fill slopes be constructed at slopes ratios of 2: 1 (horizontal and vertical) or flatter. Slopes constructed of on-site soils and/or granular soils are considered stable against deep-seated fuilures and surface sloughing when constructed at slope inclinations no steeper than the recommended 2: 1. In addition, we recommend that all fill slopes, or fill portions of cut/fill slopes, be keyed into existing formational materials and benched in accordance with our grading specifications. The importance of proper compaction of all fill materials out to the slope face cannot be overemphasized. Slopes should be either overfilled and cut back to a compacted finish surface or the outer surfuce of the fill slopes should be backrolled utilizing a sheepsfoot roller (at intervals not exceeding 4 feet in vertical height during placement) or grid rolled with standard grid rolling equipment. Permanent slope maintenance programs should be initiated immediately after the compaction of slope construction in order to minimize future surfacial sloughing. Until landscaping is fully established, plastic sheeting and installation materials should be kept 9 I I I I I I I I I I I I I I I I I I I PagelOofl4 accessible to protect the slopes from periods of prolonged and/or heavy rainfiill. Slope maintenance should include proper care of erosion and drainage control devices, rodent control, and immediate planting with deep-rooted, light-weight, drought-resistant vegetation. Experience has shown that slope performance is largely dependent upon proper slope maintenance (planting, maintaining a uniform moisture content, clearing of drainage devices, etc.). Slopes which are properly planted and conscientiously maintained are not expected to exlubit significant raveling or sloughing. DRAINAGE We recommend that measures be taken to properly finish grade the site after .structures and other improvements are completed so that positive drainage away from all floor slabs and foundations exist. Even when proper drainage measures have been taken, experience has shown that a shallow groundwater or surface water condition may develop in areas where no such water condition existed prior to site development. This is particularly true when substantial increase in surface water infiltration results from landscape irrigation. We recommend that surface drainage be designed to have a minimum two percent slope away from buildings and that all drainage water are collected and directed to discharge structures via properly designed surface swales, ditches or subsurface conduits. Installation of roof gutters and downspouts are recommended on any planned building, with all discharge being properly routed away from foundations and slabs, preferably into underground conduits. FOUNDATIONS Two requirements must be fu1fi1led by any foundation soil material. First, it should be safe against shear :fuilure of the foundation soils which would result in lateral movement of soil under the load. Second, foundation settlement or heave should be within acceptable limits for the structure. It is our opinion that the type of structures proposed for future site development can be supported on conventional, isolated or continuous footings. \t:l I I I I I I I I I I I I I I I I I I I Page II ofl4 The foundation design criteria provided herein are based on guidelines provided by the Federal Housing Authority (FHA) and the Los Angeles District Portland Cement Association (PCA). Specifically, these guidelines are intended to lessen the adverse aflects of expansive and/or compressible soils. They do not stop differential movement since structures may move in response to variation in soil moisture. These movements can and do cause some cracking of exterior stucco, concrete foundations and slab-on-grade floors. The design guidelines developed by the FHA and PCA were intended to provide foundation systems that limit cracking and other strain features to generally acceptable levels. Attempts to reduce strain features below these generally acceptable levels require engineering and construction costs typically considered inappropriate for residential construction. It should be noted that implementation of the foundation recommendations contained herein can be expected to result in some minor cracking of slabs, footings and walls, which should be considered the normal result of a necessary balance between benefits and costs. Minor cracking does not affect the serviceability of structure and is generally considered acceptable. PRELIMINARY FOOTING DESIGN We recommend that footing for light to medium-weight structures be founded in properly compacted non-expansive fill soils or formational materials. Minimum foundation for a single story structure shall be 15 inches wide and founded 18 inches below grade and shall have four #4 bars of reinforcing steel. Two bars shall be placed 4 inches below the top of foundation, and the other two bars shall be placed 4 inches from the bottom of foundation. These recommendations are based upon soil characteristics only and do not reflect any possible design considerations imposed by building design which might increase these recommendations. The proposed foundations may be designed utilizing an allowable bearing pressure of 1500 L.B./S.F. This value may be increased by 1/3 for the design ofIoads that include wind and seismic analysis. Slab on grade shall be a minimum of 4" inches thick and reinforced with #3 bar reinforcement placed on 18 inch centers both directions. This reinforcing shall be placed midway in the \\ I I I I I I I I I I I I I I I I I I I Pagel20fl4 slab. All foundations shall maintain a minimum of 7 feet of lateral support to any fill slope fuce, measured from the bottom of the foundation. The above foundation requirements are for a single story structure. In the event a two story is proposed, the minimum foundation depth shall be increased to 24 inches. ANTICIPATED PERFORMANCE OF STRUCTURES LOCATED ON FILLS AND CUTIFILL LOTS It has been our experience that structures constructed on fills with variable thickness and cut/fill lots are subjected to adjustments of the fill mass throughout the life of the structure. Such fill adjustments may produce an array of strain features in the structure. In addition, construction practices, by themselves, may also produce various strain features. A description of typical strain features that could occur are presented in Appendix E. LATERAL RESISTANCE To provide resistance for design lateral loads of footings and shear keys poured neat against vertical excavations, we recommend using a passive pressure of 350 pounds per cubic foot for properly compacted granular fill. This value assumes a horizontal surfuce for the fOoting or three time the height of the surfuce generating the passive pressure, whichever is greater. The upper 12 inches of soil in areas not protected by floor slabs or pavements should not be included in design for passive resistance to lateral loads. If friction is to be used to resist lateral loads, we recommend a coefficient of friction of 0.35 between soil and concrete. ACTIVE WALL PRESSURES We recommend that any proposed retaining walls that are unrestrained at the top and free to deflect, be designed for an active equivalent fluid pressure of 45 pounds per cubic foot. This assumes the soil behind the retaining wall will consist of compacted, non-expansive, granular soils. This also assumes level backfill conditions and that no surcharge loads \'- I I I I I I I I I I I I I I I I I I I Page I3 ofl4 exist. For walls with a sloping backfill of 2: I (horizontal to vertical), we recommend an active equivalent fluid pressure of 65 pet: For walls that are restrained at the top and have a horizontal backfill surface, we recommend an active pressure of65 pet: We recommend that a positive drainage system be incorporated into the design of retaining walls or, alternately, that walls be designed for hydrostatic pressure. Additional or final recommendations will be made and contained in the final "As Graded Report" when a more complete evaluation of foundation soils can be made. APPURTENANT STRUCTURES Construction of any proposed appurtenant structures such as pools, spas, walls, gazebos, decks, etc., should be reviewed by the Engineer in order to verifY surfuce and subsurfuce conditions and provide necessary recommendations. WARRANTY AND LIMITATIONS The recommendations and opinions expressed in this report reflect our best estimate of the project requirements based on an evaluations of the subsurface exploration locations and the assumption that the soil conditions do not deviate appreciably from the those encountered. It should be recognized that the performance of the foundations may be influenced by undisclosed 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 modifications ifnecessary. It is the responsibility of the Developer or their representative 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 plans and specifications. It is further their responsibility to take the necessary measures to insure that the contractor and his sub-contractors carry out such recommendations during construction. \3. I I I I I I I I I I I I I I I I I I I Page 14 of14 All grading shall be monitored by a qualified Civil Engineer to insure compliance with these recommendations and applicable City of Temecula Ordinances. Recommended grading specifications are included in this report as attached Exhibit "A". Attachments: Grading Specification Lab Results Boring Logs Test pit location plat Appendix E RC.E. 33220 \'\ I I I I I I I I I I I I I I I I I I I RECOl\fMEN:J}ED GRADING SPECIFICATIONS HI.. ENGINEERING & SURVEYING hereinafter described as the Soil Engineer, should be consulted prior to any site work connected with site development to ensure compliance with these specifications. These specifications shall only be used in coJ1junction with the soil report to which they are attached and made a part thereof. 1.0 Gen.eral This work shall consist of all clearing and grubbing, preparation of land to be filled, fi1ling of the land, spreatling, compacting, control of the fill, and all subsidiary work necessary to complete the grading of the filled area to conform with the lines, grades, and slopes as shown on the accepted plans. 1.1 The Soil Engineer shall test and observe all grading operations. In the event that any unusual conditions not covered by the Soil Engineer's recommendations or special provisions are encountered during the grading operations, the Soil Engineer shall be contacted for further infonnation. 2.0 Tests The standard test used to define maximum density of all compaction work shall be the ASTM Test Procedure D15S7-70. All densities shall be expressed as a relative compaction in terms of the maximum dry density obtained in the laboratory by the foregoing procedure. 3.0 OeariDlf. GmbbiDI!'. aDd PreDariDl! Areas to be Filled Any trees not utilized in landscaping, structures, weeds, and other rubbish shall be removed, piled, or otherwise disposed of so as to leave the areas that have been disturbed with a neat and finished appearance, free from unsightly debris. . ... . \5" .~ I I I I I I I I I I I I I I I I I I I 3.1 Any septic tanks, if encountered, and debris must be removed from the site prior to any building, grading, or fill operations. Septic tanks, including all connecting drain fields, and other lines, must be totally removed and the resulting depressions properly reconstructed and filled to the complete satisfaction of the supervising Soil Engineer. 3.2 All water wells on'the site shall be CliPped, according to the requirements 'oftIie San Diego County Health Department, at least two feet below the final elevations of the adjacent grade prior to any grading of fill operations. The strength of the cap shall be at least equal to the adjacent soil. 3.3 All buried tanks, if encountered, must be totally removed and the resulting depressions properly reconstructed and filled to the complete satisfaction of the supervising Soil Engineer. 3.4 All deleterious matter and soil designated as unsuitable by the Soil Engineer shall be removed under supervision and direction of the Soil Engineer. The exposed surface shall then be plowed or scarified to a depth of at least eight inches and until the surface is free from ruts, hummocks, or other uneven features which would tend to prevent uniform compaction by the equipment to be used. 3.5 The original ground upon which the fill is to be placed shaIl be plowed or scarified deeply, and where the slope ratio of the original ground is steeper than 6.0 horizontal to 1.0 vertical, the land shall be stepped or benched. At the toes of the major fills and on the sideslope fills, the base key shall be, as described elsewhere in this report, at least ten feet in width, cut at least three feet into the undistwbed or native soil, and sloped back into the hillside at a gradient of not less than two percent Subsequent keys should be cut into the hillside as the fill is brought up the slope. The construction of subsequent keying operations shaIl be determined by the Soil Engineer during grading operations. Ground slopes which 'Go I I I I I I I I I I I I I I I I I I I .', ~ are flatter than 6 to I shall be benched when considered necessary by the Soil Engineer. 3.6 After the foundation for the fill bas been cleared, plowed, or scarified, it shall be disced or bladed until it is uniform and free from large clods, brought to the proper moisture content by ..titling water or aerating, and recompacted to a relative compaction of not less than ~ percent 4.0 Materials Native soil, free of organic material and undesirable deleterious material, may be used as fill. Native soil which is expansive shall not be placed within the top three feet of the building pads without the prior approval of the Soil Engineer. 4.1 The materials for fill shall be approved by the Soil Engineer before commencement of grading operations. Any imported material must be approved for use before being brought to the site. The materials used shall be free from vegetable matter and other deleterious material, and be non-expansive. Expansive soil is defined as soil which expands more than three percent when saturated at 90 percent relative compaction and optimwn moisture content under a surcharge of 150 p.s.f. 5.0 PlaciD!!:. SpreadiD!!:. aDd Compactinl!: Fill Material The selected fill material shall be placed in layers which, when compacted, shall allow adequate bonding and compaction. Each layer shall be spread evenly and shall be thoroughly blade mixed during the spreading to ensure uniformity of material in each layer. 5.1. When the moisture content ofthcfilhnaterial is below that specified by the Soil Engineer, water shall be added until-the moisture content is as specified to assure thorough bonding during the compaction process. When the moisture content of \1 I I I I I I I I I I I I I I I I I I I the fill material is above that specified by the Soil Engineer, the fill material shall be aerated by blading or other Slitisfacto~ methods until the moisture content is as specified. 5.2 After each layer has been placed, mixed and spread evenly, it shall be thoroughly compacted to a relative compaction of not less that 90 percent 5.3 When fill material includes rock, no rock will be allowed to nest, and all voids must be carefully filled with small stones or earth, and properly compacted. No rocks larger that twelve inches in greatest dimension will be pennitted in the pad fill. All rock placement shall be continuously supervised. 5.4 Compaction shall be by sheepsfoot rollers, multiple wheel pneumatic-tired rollers, or other types of acceptable compacting equipment 5.5 Field density tests shall be made by the Soil Engineer. Where sheepsfoot rollers are used and the soil may be disturbed to a depth of several inches, density tests shall be taken in compacted material below the disturbed surface. When th= tests indicate that the density of any layer of fill or portion thereof is below the required 90 percent relative compaction, the particular layer or portion shall be reworked until the required density has been obtained. 5.6 The.fill 'Operation shall be continued in compacted layers. as specified above, until the fill has been brought to the finished slopes and graded as shown on the accepted plans. 5.7 Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment Compaction operations shall be continued until the slopes are stable. \8 .. I I I I I I I I I I I I I I I I I I I 5.8 All earthmoving and working opemtions shall be controlled to prevent water from running into excavated areas. All water shall be promptly removed and the site kept dry. 6.0 DisJJOSal of Oversize Rock Oversize rock shall be either exported from the site, used for landscaping purposes, or placed in conformance with the Soil Engineer's recommendations. 7.0 En2ineerin~ Observation Field observations by the Soil Engineer shaU be made during the fiU and compaction operations so that that Soil Engineer can express his opinion regarding the conformance of the grading with the accepted specifications. 8.0 Seasonal Limits No fill material shall be placed, spread, or rolled while it is at an unsuitable high moisture content, nor during Wlfavorable weather conditions. When the work is intenupted by heavy rains, fill opemtions shall not be resumed Wltil field tests by the Soil Engineer indicate that the moisture content and density of fill area is as previously specified. \'\ I I I I I I I I I I I I I I I I I I I HL ENGINEERING & SURVEYING 1525 S. ESCONDIDa BLVD. SUITE A ESCONDIDa, CA 92025 FAX: (760) 741-5794 (760) 741-0533 SOIL BORING LOG PROJECT NAME:lot 107 Carmelita Circle DATE:8I8I02 EXCAVATION NO. ONE DESCRIPTION DEPTH SAMPLE MAXIMUM DRY MOISTURE SOilS AND REMARKS {FEET! TYPE DENSITY (PCF' CONTENT (%) CLASSIFICATION 1 TAN. MEDIUM DENSE SM SILTY FINE SAND 2 3 4 b,,----------------------------- (GRANITIC FORMATION) 5 6 - ----------- --------------- ------------- BOTTOM OF-pTT--------------- 7 8 9 10 11 JOB NO. 5278 20 I I I I I I I I I I I I I I I I I I I HL ENGINEERING & SURVEYING 1525 S. ESCONDIDO BLVD. SUITE A ESCONDIDO, CA 92025 (760) 741-0533 FAX: (760) 741-5794 SOIL BORING LOG PROJECT NAME:Lol107 Cannelita Circle DATE:8I8I02 EXCAVATION NO. TWO DESCRiPtiON DEPTH SAMPLE MAXIMUM DRY MOISTURE SOiLS ANO REMARKS (FEETl TYPE DENSITY (PCF CONTENT (%\ CLASSIFICATION 1 SM TAN, LOOSE SILTY SAN 0 2 FILL (REMOVE AND RECOMPACT) 3 BULK 130 4.1 4 5 TAN, KfEOim.HiENSE--------------------- 61-- ----------- SM SILTY FINE SAND -------------- ----------------- -='.=------------------ BOTTOM OF TEST PIT 7 8 9 10 11 JOB NO. 5278 2.\ I I I I I I I I I I I I I I I I I I I HL ENGINEERING & SURVEYING 1525 S. ESCONDIDO BLVD. SUITE A ESCONDIDO, CA 92025 (760) 741-0533 FAX: (760) 741-5794 SOIL BORING LOG PROJECT NAME:Lot 107 Carmelila Circle DATE:818102 EXCAVATION NO. THREE DESCRIPTION OEPTH SAMPLE MAXIMUM DRY MOISTURE SOILS AND REMARKS (FEET) TYPE DENSITY (PCF CONTENT/%l CLASSIFICATION 1 SM TAN, MEDIUM DENSE SILTY FINE SAND 2 3 4 5 f-------------------------------------------- --------- ~------------- (GRANITIC FORMATION) 6 ------------ --------------- IS-------------------------- BOTTOM OF TEST PIT 7 8 9 10 11 JOB NO. 5278 2.2.. \ I~ , I "" '\ '\ I" '\ \ '\ . \ "- . \ \ \ \ \ \ ~ 1\ \ \ -- '<::) - I <> ~ <:> I ~ I \ I I ( , " "- , , '.... /I?.?~~A-IL C;CCAi//fT/o,v Loc..;;;. 7:.!J, N \ ~ ~ \ ..... ...../42.4-6' : ___ \ ) I , ......... .... ~ __ ___ ---......-. I \ " " " , --........ .... , ~ ~ .....,"- '" " " , '\ "" I~ .... ..... " ..... ~.. ...... .... " .... .... , I \ ',~\~,:; \ :~s ',~ \ \ ' \. I I'" I 1 ':;\ :1 ~, I I" l" . I ~: ~ ~\ ~ ;c ) 'I ' ,\ " \ " ~.... <(::to ..... ....' ~<:l::"" ~ ,,~ <l \J\ -Q'-.., ......... ~ ....... ~\J It ~~ ?5..... In \,;; 0/ M~ ..... 1If>;) v' ~. ....... ..... .... '" ..... " "- - , "" ..... , , ",- .....~~ \01 ..... " .... r i 5: ~ :4 V ~ \ t;, '" \1t 1(.,., I~ , M ( I N 4~'>gI/2"W- I '" COI'IS,TI<UCT ,CONe. 0 Wllyl PE/i! S/'rY S'T~. '207 \ , ~Em" ~ TRAvE' WAY..--/ L ,CA~/>?C'(./~A C/",c~G . I l "- , I.!l '" '\ CD a ~ '" :?~ ~~\ % ... \!l~ 2:~ \A' "- " 3 \ ~ OJ \ ~t,J I \ C) ~~ ~ \ \j ~\ ~l( C(:~. -1- I 1 ~ l'lQ · (~'I-'''~...f, \ 1""j..1 /. ~llo\; 5 ( I,) f~fo"" ~V <> ~ f -.... ~ ( Nt .----.. ~.. , \ ,. pc> ; '" \. ~ ....:: , l.., .... \ . 10' <l r:; 1 t- I I \ ~ \ \ '. ~ \~ \ \.it \ IX) , I ~ . . \ <l -: \ \ \ I \ 122' \ I / -.-.... / \ \ '-""::' ,2;0 \ I I I I 1 1 1 1 1 1 1 I I 1 1 I 1 1 I APPENDIX E ORIGIN OF STRAIN FEATURES AND CONSTRUCTION PRACTICES L ORIGIN OF STRAIN FEATURES Strain features, for example cracks in walls and slabs, are a result of deformation of the house and improvements under the action of forces. Some of these forces may originate in the underlying soil; however, other forces originate as a result of construction methods and materials. These origins of forces often interact as contributing factors. The goal of construction practice and engineering is to limit development of strain featUres to generally accepted levels. An attempt to reduce strain features below generally accepted levels requires more expensive engineering and construction. In addition to cracks in walls and slabs, strain features include the following: bulges at wallboard seams, out-of-square door and window frames that cause rough operation, cracked footings, displacement of separate structural elements such as between walls and chimneys or across contraction joints in slabs, and unusual variations in topography of the floor slab. II. CONSTRUCTION PRACTICES Some cracking of slabs, footing, and walls is considered normal and is the result of a necessary balance between benefits and costs. Minor cracking does not affect the serviceability of a house and has been considered generally acceptable. In some conditions a concrete slab or footing may develop a single large crack or numerous small cracks. Data I in Engineering Bulletin No.3, Design and Control of Concrete Mixtures by the Portland Cement Association, indicated that a high-quality slab or footing that is 50 feet in dimension may experience 0.36 inches of shrinkage during the 2.",\ I I I 1 I 1 1 1 I I I 1 1 1 1 I 1 I 1 first 38 months after construction. Approximately 0.12 inches of shrinkage would occur during the first month and an additional 0.2 inches would occur in the next 10 months. Moreover, concrete in residential structures is often placed with high water content, high initial temperatures, small aggregate, and during hot and dry weather conditions. All of these can increase the amount. of shrinkage. In some slabs, the shrinkage may be expressed as one or two cracks rather than being distributed as small shrinkage cracks. m. CAUSES OF PLASTIC SHRINKAGE CRACKS AND RECOMMENDED CORRECTIVE MEASURES These highly unsightly cracks are caused by a rapid eVaporation of water and surface drying of fresh concrete. Plastic concrete shrinkage cracks can be minimized by using good construction practices; sUch practices are listed below: 1. Saturate the subgrade and forms. 2. Lower the temperature of the concrete in hot weather (over 850F). 3. Reduce the time between placing the concrete and finishing it. 4. Provide environmental controls, such as sun-shades, windbreaks or temporary coverings. 5. Don't overwork finishing effort as this will Cause separation of aggregates and bring excessive water to surface. 6. Provide expansion/contraction joints. These may be accomplished by "cold joint", expansion material joint, or sawcut, within 24 hours of pour. The Engineer will be gIad to review your building plans and provide recommendations. 7. Avoid adding excessive water to PCC mix, as this reduces concrete strength and contributes to cracking. 2S