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HomeMy WebLinkAboutX2009-0888 - Soils)(10001 _ obb-b Z 23oG Mare -et b r- BAGAHI ENGINEERING INC. GEOTECHNICS & FOUNDATIONS 71 GREAT LAWN IRVINE, CA 92620 TEL (949) 552-2006 • FAX (949) 552-2007 April 22, 2009 MR. AND MRS. BRIAN ELLERBROEK Project No.: 198n-200-00 C/O Mr. J.P. Anderson �oFPa�� Ev4� oR a�euFo eu u\N Ex ESs 2005 YachtResohrte �� Auu ��v TvTOT a � yes Newport Beach, CA92660 COS SUBJECT: PRELIMINARY GRTENI �NIrfESTIGAT1t)1� Proposed Single Famd ' ri$ent e a 2306 Margaret Drive e �` � �� ' ��� I v Nweport Beach, Cahfor a i---- - � SEES RC•Ad�^ / � / Dear Mr. Anderson: In accordance with your request, we have completedoul prcitzmge�ohnical investigation for a proposed single family residelec at"ihe'subj�-site. As part of our investigation, we performed subsurface drilling, sampling, Iab-ooratory testing of selected soil samples, and analysis of data. The attached report presents the results of our investigation and our findings and recommendations. The opportunity to be of service is appreciated. If you have any questions, please do not hesitate to call us. r a Very truly yours,�� BAGAHI ENGINEERING IN NO �. `'_,..�,.m �Yf 3 •e'er -., � V Ken H. Bagalu, Ph. ., I.E. 108 �a F c x�V Sergio Uutieirez Principal Staff Geologist KHBIIb Distribution: (1) Mr. and Mrs. Brian Ellerbroek (2) Mr. Pete Anderson Pr- I 98n-200-OO.da PRELIMINARY GEOTECHNICAL INVESTIGATION PROPOSED SINGLE FAMILY RESIDENCE 2306 Margaret Drive Newport Beach, California Prepared For: MR AND MRS. BRIAN ELLERBROEK C/O MR. J.P. ANDERSON 2005 Yacht Resolute Newport Beach, CA 92660 Prepared By: BAGAHI ENGINEERING INC. 71 Great Lawn Irvine, CA 92620 Job No. 198n-200-00 April 22, 2009 TABLE OF CONTENTS INTRODUCTION................................................................................................ 4 Purpose...................................................................................................... 4 Proposed Construction.............................................................. 4 Scopeof Services....................................................................................... 4 SiteDescription......................................................................................... 5 SUBSURFACE INVESTIGATION...................................................... 5 Site Exploration....................................................................... 5 Laboratory Testing.................................................................................... 6 GEOLOGIC AND SOIL CONDITIONS................................................................ 6 RegionalSetting.......................................................................................... 6 LocalSetting.............................................................................................. 6 Subsurface Conditions ........................... .. 8 Seismic Design and Liquefaction Potential .................................... 8 CONCLUSIONS AND RECOMMENDATIONS.................................................. 8 Site Preparation and Grading....................................................... 8 Foundation and Slab Recommendations...................................................... 10 RetainingWalls........................................................................................... 12 ConcreteFlatwork...................................................................................... 14 TrenchBackfill ------------------------------------------------------------------------------------------ 15 Temporary Excavations.............................................................................. 15 Surface Drainage..................................................................... 16 Planters................................................................................ 17 Typeof Cement....................................................................... 18 PlanReview........................................................................... 18 Pre -Construction Meeting.......................................................... 19 Supplemental Consulting........................................................... 19 LIMITATIONS............................................... I ........ I ............. ....... 1 20 APPENDIX A — SUBSURFACE EXPLORATION APPENDIX B — LABORATORY TESTING Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 PRELIMINARY GEOTECHNICAL INVESTIGATION 2306 Margaret Drive Newport Beach, California f Zo Y ti01011S11A PURPOSE M This report presents the results of our preliminary geotechnical investigation for a proposed single family residence in Newport Beach, California. The purpose of our investigation was to perform subsurface, investigation to evaluate subsurface conditions for the proposed construction. Conclusions and recommendations relative to the site grading, footing foundation design, slab subgrade design, retaining wall design, temporary excavations, and type of cement for construction are presented herein. PROPOSED CONSTRUCTION We understand that the proposed construction will consist of demolition of an existing house on the site and construction of a new detached one-story residence with a central two-story portion. Other improvements include a circular entry driveway and associated hardscape. Structural computations indicate typical maximum loads of 1.3 kips/ ft for the wall and 8 kips for the columns. Loading to be verified by the Structural Engineer. SCOPE OF SERVICES The scope of services provided during the course of this investigation included: a. Subsurface exploration consisting of two auger borings, Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 Page 5 b. Logging and sampling of the borings and collection of soil samples for laboratory testing, C. Laboratory testing of soil samples representative of subsurface conditions encountered in the borings, d. Geotechnical analysis of field and laboratory data to develop site stratigraphy and provide a basis for our conclusions and recommendations, and e. Preparation of this report presenting our findings, conclusions and recommendations. SITE DESCRIPTION The project site is a relatively flat lot and is occupied by a one-story house. The lot is currently about 3 feet above the street grade. Much of the front yard is covered with lawn and two mature trees. The lot drains to Margaret Drive. The site is bounded by residential properties on three sides and by Margaret Drive along the south side. SUBSURFACE INVESTIGATION SITE EXPLORATION Subsurface conditions for this study were explored by drilling two auger borings to a maximum depth of 10 feet. The approximate locations of the borings are shown on the Plot Plan in Appendix A. Sampling included collection of bulk samples from cuttings derived during drilling, and ring samples. Relatively undisturbed samples (rings) were obtained using a modified hand sampler. The soil samples were retained in a series of brass rings each having an inside diameter of 2.41 inches and height of 1.0 inch. These rings were placed in close -fitting, moisture -tight containers for shipment to the laboratory for testing. Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 ri Continuous logs of the subsurface conditions, as encountered in the borings, were recorded at the time of the drilling. A summary of these conditions is given in the log of borings in Appendix A. Test borings were located in the field by pacing from known landmarks. Boring locations as shown are therefore within the accuracy of such measurement. Subsequent to logging and sampling, the test holes were backfilled and tamped utilizing the soils excavated. LABORATORY TESTING Laboratory tests on both bulk and split spoon samples of the on -site soils were performed as part of this investigation to determine engineering properties of the subsurface materials. The details of the laboratory testing program and the test results are presented in Appendix B. GEOLOGIC AND SOIL CONDITIONS REGIONAL SETTING The subject property is situated in the Peninsular Ranges province. The Peninsular Ranges province is one of the largest geomorphic units in western North America. This province varies in width from about 30 to 100 miles. It is bounded on the west by the Pacific Ocean, on the south by the Gulf of California and on the east by the Colorado Desert Province. The peninsular Ranges are essentially a series of northwest -southeast oriented fault blocks. Three major fault zones are found in this province. The Elsinore Fault zone and the San Jacinto Fault zones trend northwest -southeast and are found in the near middle of the province. In the vicinity of the subject site area, the Newport Inglewood fault zone is located a few miles to the south_ LOCAL SETTING In the regional vicinity of the subject site, the underlying materials are Quatemary/Recent alluvium deposits, Quaternary/Upper Pleistocene marine terrace deposits (Qtm), and Tertiary marine sandstone, diatomaceous siltstone and shale of the Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 7 Monteray Formation (Tm). The alluvium mantles much of the Coastal Plain of Orange County, but was not encountered onsite. SUBSURFACE CONDITIONS Based on the results of this investigation and laboratory testing, the subsurface materials at the subject site consist of one and a half to two feet of silty sand underlain by several feet of brown sandy silt over orange brown silty sand to the maximum explored depth of 10 feet. Laboratory consolidation testing of a soil sample from shallow depths exhibited little compression under anticipated loads. An expansion index test on a sample from near -surface soils showed a medium expansion potential. No groundwater was reached in our borings. Depth to groundwater is seasonal and variations from our observation is likely. SEISMIC DESIGN AND LIQUEFACTION POTENTIAL For seismic design purposes, and utilizing the 2007 CBC edition, the following seismic factors would apply to this site: • Seismic Design Category - D • Site Class: D • Mapped 0.2 Second Spectral Response Acceleration, Ss = 1.820g • Mapped one Second Spectral Response Acceleration, SI = 0.678g • Site Coefficient, Fa = 1.0 Site Coefficient, Fv = 1.5 • 5% Design Spectral Response Acceleration, SDs=1.213g • 5% Design Spectral Response Acceleration, SDI = 0.678g The site is not mapped as prone to liquefaction by State of California Seismic Hazard Zones Map. Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 Page 8 CONCLUSIONS AND RECOMMENDATIONS From a geotechnical engineering standpoint, it is our opinion that the proposed construction at the subject site would be feasible and would not impact adjacent properties provided the recommendations and conclusions presented herein are incorporated into the prgjectdesign, plans and specifications, and implemented during construction. The structure may be supported on footings and slab -on -grade. Recommendations for site preparation and grading, subgrade preparation for footings, slab -on -grade, temporary excavations, and type of cement for construction, are presented in the following sections. All foundations and slabs should be properly reinforced in accordance with recommendations of the Project Structural Engineer. It is anticipated that the near -surface subgrade soils will have a medium expansion potential. Expansion index tests should be performed at completion of rough grading to verify soil expansion potential. Grading and foundation plans are not available at this time. These need to be submitted to our office for review and compliance with recommendations presented herein and for possible modifications to these recommendations. SITE PREPARATION AND GRADING 1. Clearing and Stripping All existing utilities, concrete, buried obstructions, trees, vegetation, debris, or other deleterious substances within the proposed building, improvement areas and areas to receive fill and extending to 5 feet beyond these areas or to property line should be removed. Root bulbs shall be removed and excavation backfilled with sandy soils, placed in lifts and compacted to a minimum of 90% relative compaction per ASTM D-1557. Debris and rubble from the clearing operations should be removed from the site. Any existing disturbed loose soils should be removed and replaced with properly compacted fill material. Depressions resulting from the removal of unsuitable materials, which extend below finished site grades, should be ___,backfilled with properly compacted fill. Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 Page 9 2. Subgrade Preparation Slab -on -grade and footing subgrade areas and extending to 5 feet beyond or to the property line should be overexcavated a minimum of 2 feet below the bottom of proposed footings and recompacted to a minimum of 90 percent . relative compaction in accordance with ASTM D-1557. Subgrade for driveway and hardscapes shall be overexcavated a minimum of six inches, the bottom scarified and moisture conditioned to near optimum moisture and recompacted. The depth of overexcavation should be reviewed by the Geotechnical Consultant during construction. Any surface or subsurface obstructions, buried structural elements, and unsuitable material encountered during grading, should be brought to the attention of the Geotechnical Engineer for proper exposure, removal and processing as recommended. Bottom of overexcavation shall be scarified, moisture conditioned and proof rolled prior to fill placement. All exposed surfaces in the excavations should be observed and approved by this office prior to backfilling. Any localized dry or loose subgrade conditions observed at excavation levels should be excavated and backfilled with compacted granular fill. No excavation shall extend below the bottom of foundation of adjacent structures unless special precautions such as shoring are taken to protect the adjacent structures as discussed under "Temporary Excavations." 3. Import Fill Material Any import fill material for subgrade should be well graded, predominantly granular, have an expansion index less than 20, and be approved by the Geotechnical Engineer prior to importing. Much of the on -site sandy soils may be used as fill provided that they are granular, free of roots, silty soils, debris and rock fragments exceeding 4 inches. Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 I April22, 2009 Page 10 4. Fill Placement and Compaction Import and on -site fill materials should be placed at a moisture content near the optimum and about 3 percent over optimum, respectively; compacted to at least 90 percent relative compaction as determined by current ASTM D-1557, the Five -Layer Method. All fill should be placed and compacted in horizontal loose lifts not exceeding 6 inches. 5. Drainage Positive surface gradients should be provided adjacent to all structures so as to direct surface water runoff drainage away from foundation, exposed slopes, and slabs, and toward suitable discharge facilities. Recommended minimum gradient is two (2) percent for unpaved areas and one percent for concrete areas. Pondings of surface water should not be allowed on slabs. Roof gutter discharge should be directed away from the building area through solid PVC pipes to suitable discharge points. FOUNDATION AND SLAB RECOMMENDATIONS 1. General Based on the results of our geotechnical evaluation, combined with engineering analysis and our experience and judgment, it is our opinion that a foundation system consisting of footings may be used for supporting the proposed resistance. The following footings and slab recommendations are based on the subsurface conditions observed in the borings and the soils presently exposed at grade and are considered generally consistent with the Standards of Practice. Subgrade soils are expected to have a medium expansion potential. Implementing these recommendations should reduce the risk of distress resulting from expansive soils but some risk always remain as there is no simple economically feasible method of treating such soils. The potential for favorable foundation performance can be further enhanced by maintaining proper site drainage. The footing and slab configurations and reinforcement recommendation herein should not be considered to preclude more restrictive criteria by the governing agencies or by structural considerations. A Structural Engineer should evaluate Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 Page 11 configurations and reinforcement requirements for structural loadings, shrinkage, temperature and subgrade stresses. Expansion index of the soils exposed at grade should be determined following rough grading and these recommendations re-evaluated accordingly. wucri;� 15 -�140 vai)N'� Oil 2. Footings I �. (.��. 'It 2 '!f &(o /a i"CW) Footings in compacted granular fill nay be designed for an allowable soil bearing pressure not exceeding 2006 psf,)and should be founded at least 18 inches below the lowest adjacent soil grade. The minimum footing width is 15 inches. Footings should be reinforced by at least two # 4 bar at top and bottom unless greater reinforcement is needed based on Structural considerations as determined by the Structural Engineer. Footings located adjacent to utility trenches should extend below a one-to-one plane projected upward from the inside bottom corner of the trench. Footings shall be doweled into the slab with at least #4 bars at 24-inch spacing. The allowable bearing pressure may be increased by one-third under seismic loading conditions. For properly designed and constructed footings, the anticipated differential settlement is less than half an inch over a span of 20 feet. Under seismic loading condition, additional settlement is to be anticipated. A grade beam reinforced continuously with the garage footings should be constructed across the garage entrance. This grade beam should be embedded at the same depth as the adjacent perimeter footings. 3. Lateral Load Resistance of Footings Resistance to lateral loads on footings can be assumed to be provided by passive earth pressure and by friction acting on structural components in permanent contact with subgrade materials. An allowable friction coefficient of 0.3 may be used with dead load forces between the bottom of the footing and the supporting undisturbed or compacted granular soils. A passive earth pressure equal to an equivalent fluid pressure of 200 pef acting against the perimeter footing may be used, provided the footings are poured tightly against competent soils. A maximum allowable passive pressure of 1500 psf may be used. The passive resistance assumes that the earth material providing the resistance is uninterrupted for a minimum horizontal distance of three times the foundation depth. When, combining passive with friction, the passive shall be reduced by 1/3. Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 12 Foundation excavations shall not be left open over an extended period of time. All footing excavations should be observed by the Geotechnical Consultant. 4. Slab -on -Grade All floor slab subgrades should be prepared in accordance with the recommendations under "Site Preparation and Grading, Subgrade Preparation." Slab -on -grade floors should be designed by the Structural Engineer using applicable CBC requirements and designed for the intended use and loading. As a minimum, slabs should be reinforced with # 4 bars at 18-inch spacing, located at mid -height of the slab. Actual slab reinforcement and thickness to be determined by the project Structural Engineer based on effective plasticity index as discussed below. Thickness of floor slabs should be at least 4 inches actual and determined by the project Structural Engineer for the project loading and service conditions. Slabs in moisture sensitive areas should be underlain by a minimum of 2 inches of rounded gravel or clean coarse sand base and a minimum of 10-mil thick polyethylene moisture retarder membrane, plus an additional 2 inches of fine to medium coarse sand between the moisture retarder membrane and the slab. Moisture retarder membrane shall be properly lapped and sealed. Another alternate is to place the concrete directly on the moisture, retarder membrane, provided the membrane is at least 15 mil thick to minimize potential puncture from concrete aggregate. This alternate diminishes potential upward vapor movement through the slab. Garage floor slabs should be poured separately from adjacent wall footings with a positive separation maintained with 3/8-inch-minimum felt expansion joint materials, and quartered with weakened plane joints. Slab thickness and reinforcement for building slab -on -grade should be designed in accordance with 2007 C.B.C. section 1805.8.2 using an effective plasticity index of 20. The design is referred to the project Structural Engineer. RETAINING WALLS Retaining walls planned should be adequately designed to resist the lateral soil pressures and the anticipated construction loadings and service conditions. The earth pressure acting on retaining walls depends primarily on the allowable wall movement, type of backfill materials, backfill slopes, wall inclination, surcharge loads, and any hydrostatic pressure. Recommended lateral earth pressure criteria for vertical walls with level backfill, no hydrostatic pressure and no surcharge loading, are shown. below: Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 Page 13 EQUIVALENT FLUID PRESSURE (pet) SOIL TYPE EARTH PRESSURE Active At -Rest On -site sandy soils 45 55 Import clean sands 35 50 The active earth pressure values provided may be used for cantilevered retaining walls. Restrained retaining walls such as basement walls, that are not free to rotate at top, should be designed using the at -rest earth pressure values. Depending on whether the wall is restrained (rigid) or unrestrained (free to deflect), an additional uniform lateral pressure equal to 50 or 33 percent, respectively, of the anticipated maximum surcharge load located within a distance equal to the height of the wall should be used in the design. Import soils used for retaining wall backfill should be predominantly granular, with an expansion index of less than 20, and free of organic material and rock in excess of four inches maximum dimension. Retaining wall foundation in bedrock should be designed in. accordance with the recommendations under "Foundation and Slab Recommendations". Walls should be adequately drained to prevent build-up of hydrostatic pressures. Wall drains should be directed to an approved outlet. As a minimum, the wall may be drained by placing a 4-inch perforated PVC Schedule 40 pipe or approved equivalent, with perforation placed down behind the base of the wall. The pipe should be surrounded by 3/4-inch crushed rock at a rate of not less than one cubic foot per linear foot of pipe surrounded in turn by a geofabric such as Mirafi 140NC or equivalent. The drain shall be connected to a solid PVC pipe Schedule 40 or equivalent leading to an approved outlet. All wall backfill should be mechanically compacted to a minimum of 90 percent relative compaction in accordance with ASTM D-1557-78. If a limited area exists behind the wall, geotextile drain mats such as Mirafi Miradrain or equivalent, can be used in lieu of a conventional pipe and gravel drainage system. The drain mats should extend the full height and lengths of the walls, and the filter fabric side of the drain mats should be placed against the backcuts. The perforated pipe drain lines placed at the bottom of the drain mats should consist of 4-inch minimum diameter PVC Schedule 40 or ABS SDR-35. The filter fabric on the drain mats should be peeled back and then wrapped around the drain line. If imported pea gravel or crushed rock is used for backfill, the gravel should be placed Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 Page 14 in approximately 2 to 3 foot -thick lifts, thoroughly wetted but not flooded, and then mechanically tamped or vibrated into place. A representative of the project geotechnical consultant should observe the backfll procedures and probe the backfi l to determine that an adequate degree of compaction is achieved. To mitigate the potential for the direct infiltration of surface water into the backfill, imported sand, gravel, or rock backfill material, the backfill should be capped with at least 30 inches of on -site soil. Filter fabric such as Mirafi 140N or equivalent, should be placed between the soil and the imported gravel or rock to prevent fines from penetrating into the backfill. Proper surface drainage such as a concrete V-ditch should be provided along the top of walls. Down drains (outlets) for surface drainage or other subdrainage systems should not be tied into the subdrain system for walls. Wall subdrains should outlet separately and not be combined with area drains. SEISMIC LATERAL EARTH PRESSURE Incremental increase in lateral active earth pressure on retaining structures due to seismic loading may be computed using an inverted triangular distribution with a horizontal force of 7 HZ pounds per foot of wall acting at 0.6 H from the base where H = height of the retained earth in feet. All values are for a level backfill, no hydrostatic pressure and a vertical wall. CONCRETE FLATWORK Concrete flatwork should be supported on properly compacted fill. Subgrade should be prepared in accordance with the recommendations under "Subgrade Preparations". To reduce the potential for cracking, concrete flatwork such as walkways, should be a minimum of 4 inches thick and provided with construction or weakened plane joints at frequent intervals of less than every 5 feet in both directions. A two-inch layer of fine gravel or clean sand beneath the slab and moistening of the slab subgrade are recommended. Reinforcing the slab may also be considered as determined by the Structural Engineer. Flatwork subgrade should be observed by the Geotechnical Consultant prior to concrete pour. To mitigate cracking and/or shifting of concrete flatwork, the subgrade soils below concrete flatwork areas should be thoroughly moistened prior to placing concrete. The moisture content of the subgrade soils should be at least 120 percent of optimum Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 IN moisture content to a depth of approximately 12 inches. Flooding or ponding of the subgrade is not considered feasible to achieve the above moisture conditions since this method would likely require construction of numerous earth berms to contain the water. Therefore, moisture conditioning should be achieved with sprinklers or a light spray applied to the subgrade over a period of several days just prior to pouring concrete. A representative of this firm should observe and verify the density and moisture content of the soils, and the depth of moisture penetration prior to pouring concrete. TRENCH BACKFILL It is our opinion that utility trench backfill consisting of onsite material types could be placed and compacted by mechanical means. The backfill should be compacted to a minimum of 90 percent relative compaction in accordance with ASTM D-1557. If trench depth exceeds 5 feet, fill placement and compaction method should be reviewed and approved by the Geotechnical Engineer. For trenches in areas subject to vehicular traffic, a minimum of 3 feet of cover should be provided over the conduit. Utility trenches extending below a 1:1 (horizontal:vertical) projection from the outer edge of a foundation should be backfilled with lean concrete (3-sack) within the influence zone of the foundation. Backfill compaction should be tested at vertical intervals not exceeding 2 feet. Also field density tests should be performed for every 200 lineal feet of trench, or as specified by the governing agency. Governing agencies typically require that the compaction of all utility trench backfills be tested and discussed by the project soils engineer prior to completion of the project. To give our opinion on the adequacy of the backfill, we need to be notified ahead of time prior to the start of and during the backfill placement and compaction to observe the backfilling method and perform compaction testing as the work progresses. If testing is performed after completion of backfilling without observing the backfill placement method, only the test results at the test locations will be reported. TEMPORARY EXCAVATIONS All excavations and shoring systems should meet the minimum requirements given in Article 6 of the State of California Occupational Safety and Health Standards. The contractor is solely responsible for the stability of temporary slopes and safety and maintenance of such excavations_ Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 Page 16 Temporary excavations less than 3 feet in height may be made vertically. Excavations exceeding 3 feet in height should be no steeper than 1:1 gradient (horizontal:vertical) or properly shored. Excavations should be kept moist but not saturated and not allowed to dry to a significant degree i.e. formation of desiccation cracks prior to placement of backfill. Temporary excavations should be backfilled as soon as practical but not exceeding a few days. Excavations that extend below an imaginary plane inclined at 45 degrees below the edge of any nearby adjacent existing site facilities should be properly shored to maintain foundation support of the adjacent structure. Slope and excavation faces should be covered with plastic sheets during rainfall periods to avoid saturation of the cut areas. The above criteria are intended as general guideline only. The Geotechnical Consultant makes no warranties either express or implied as to the stability of temporary construction slopes. Soil conditions may vary locally and therefore site -specific evaluation of temporary slopes will be required. Some sloughing of the cut slope, particularly in areas exceeding 3 feet in height may take place. All loose soil and debris at the bottom of excavation should be removed. SURFACE DRAINAGE To enhance future site performance, it is recommended that positive measures be taken to properly finish grade the improvements so that drainage waters from the lot and adjacent areas are directed off the lot and away from foundations, slabs, and adjacent property. For earth areas adjacent to the structure, a minimum drainage gradient of 2 percent is recommended. Drainage patterns approved at the time of fine grading should be maintained throughout the life of the proposed structures. Landscaping should be kept to a minimum and where used limited to plants and vegetation requiring little watering as recommended by a registered landscape architect. Roof drains should be directed off the site and slope areas. The property owner should be aware that altering drainage patterns, landscaping, the addition of patios, planters, and other improvements, as well as irrigation and variation in seasonal rainfall, all affect subsurface moisture conditions, which in turn affect structural performance. DRAINAGE CONTROL DURING GRADING Precautions should be taken during the performance of site clearing, excavations and grading to protect the work site from flooding, ponding or inundation by poor or Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 17 improper surface drainage. Temporary provisions should be made during the rainy season to adequately direct surface drainage away from and off the work site. Where low areas cannot be avoided, pumps should be kept on hand to continually remove water during periods of rainfall. Following periods of rainfall and at the request of the Geotechnical Consultant, the Contractor shall make excavations in order to evaluate the extent of rain -related damage. PLANTERS Planters that are located within 5 feet of building foundation, retaining walls, masonry garden walls and slope areas should be provided with sealed bottoms and bottom drains to prevent infiltration of water into the adjacent foundation soils. The surface of the ground in these areas should also be maintained at a minimum gradient of 2 percent and drainage directed to surface area drains. The sealed planter bottoms should consist of either reinforced concrete having a minimum thickness of 4 inches, or a polyvinyl chloride membrane of sufficient thickness to prevent puncturing by plant roots. If concrete is used to line the planters, minimum reinforcement should consist of No. 3 bars spaced at 18 inches on centers, both ways, or 6-inch by 6-inch, No. 6 by No. 6 welded wire mesh. If a polyvinyl chloride membrane is used, a minimum thickness of 30-mils is recommended. Furthermore, the bottoms of the planters should be sloped to direct subsurface water to collectordrains connected to drain lines designed to carry water to adjacent street. MASONRY BLOCK WALLS Masonry block walls may be supported on footings as discussed previously. Footing should be poured monolithically with continuous reinforcement of at least two No. 4 bars top and bottom. To minimize potential for cracks through the wall as a result of differential settlement, a separation joint (minimum width of 1/8-inch) shall be provided at each bend in the wall and at horizontal internals about 20 feet. Joint shall not extend into footing. Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 FENCE AND/OR GARDEN WALLS In Garden wall footings should be founded a minimum of 12 inches below the lowest adjacent grade. To reduce the potential for unsightly cracks, we recommend inclusion of construction joints at 10 to 20 foot intervals. Due to the soil expansion characteristics, some tilt of the wall should be anticipated for walls which are constructed close to the top of slopes having high or very high soil expansion potential. To reduce the potential for tilting, deep footings consisting of a minimum 12-inch diameter and 8-foot deep caissons at a minimum spacing of 8 feet on center connected together by a 12-inch wide by 12-inch deep grade beam located on or above the ground surface may be considered. TREE WELLS Tree wells are not recommended in concrete flatwork areas since they can introduce excessive water into the subgrade soils or allow for root invasion, both of which can result in uplift of the flatwork. Trees are not recommended within 12 feet of the structure to mitigate against potential loss of subsurface moisture that can result in settlement. TYPE OF CEMENT A sulfate test was performed on a sample of near -surface sandy soils. The test results are presented in Appendix B and indicate low sulfate content. It is recommended that all concrete in contact with subgrade soils meet as a minimum the requirements of 2007 C.B.C, Section 1904.3 for concrete exposed to at least negligible sulfate exposure. A concrete expert shall be consulted for appropriate concrete mix design. PLAN REVIEW Grading, foundation and landscaping plans including the final structural design loads should be made available to us for review to verify conformance of these plans with the intent of the recommendations contained herein prior to permit application. Our review deals with general conformance of plans with our geotechnical recommendations and does not include review of accuracy of dimension, Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 Page 19 measurements, calculations, design or other professions inputs. Our review is not intended to evaluate an entire system of which a component is reviewed. Any soils imported to the site for use as subgrade fill or backfill materials should be tested and approved by the Geotechnical Engineer prior to importing. Site preparation and grading work and fill testing including testing of wall and trench backfills as well as observation of the footing excavations should be performed under the observation and testing by the Geotechnical Engineer or his representative. PRE -CONSTRUCTION MEETING An on -site pre -grading meeting should be arranged between the representative of the Owner, the Geotechnical Engineer, the Grading Contractor and representatives of the governing agency prior to start of construction to review the site conditions and the geotechnical observation, testing and documentation requirements during construction. SUPPLEMENTAL CONSULTING During construction, a number of geotechnical reviews and observations by this office are recommended to verify site geotechnical conditions and conformance with the intentions of the recommendations for construction. Although not all possible geotechnical observation and testing services are required by the Governing agency, the following site reviews are advised, some of which are required by the Governing agency. • Observation of bottom of footing excavations .................................................Required • Observation of bottom of foundation excavation for appurtenances ...............Required • Reinforcement placement for all foundations .......Advised • Slab subgrade moisture retarder membrane placement ....................................Advised • Slab and flatwork subgrade observation prior to concrete placement...............Advised • Slab steel placement, primary and appurtenant structures.................................Advised • Moisture and expansion index checks for all slabs for primary structure • Moisture and expansion index checks for all slabs for appurtenant structures........ .......Required .1................................Required • Observation and testing of overexcavation and recompaction.........................Required Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 Page 20 and utility trenches.................................................................................Required LIMITATIONS Our investigation was performed in accordance with generally accepted practice in the geotechnical field. No warranty, expressed or implied, is made as to the conclusions and professional advice included in this report. The samples taken and used for testing and the observations made are believed representative of the entire project; however, soil conditions can vary significantly between observation points. As in most projects, conditions revealed by excavation may be at variance with preliminary findings. If this occurs, the changed conditions must be evaluated by the Geotechnical Consultant and designs adjusted as required or alternate designs recommended. It should be understood that the geotechnical consulting provided and the contents of this report are not perfect. Any errors or omissions noted by any party reviewing this report and/or any other geotechnical aspects of the project, should be reported to this office in a timely fashion. This report is intended for design of this specific project and for sole use and benefit of our client. It is not intended to necessarily be adequate for a contractor to provide a fixed price bid or for a client to expect that no changed conditions will exist. Subsequent use of this report can only be authorized by the client. Any transferring of information or other directed use by the client should be considered advice by the client. Conclusions and recommendations presented herein are partly based on the evaluations of technical information gathered, partly on experience and partly on professional judgment. The conclusions and recommendations presented should be considered "advice". Other consultants could arrive at different conclusions and recommendations. Typically "minimum" recommendations have been presented. Although some risk will always remain, lower risk of future problems would usually result if more restrictive criteria were adopted. Final decisions on matters presented are the responsibility of the governing agencies and/or the client. Observation and testing by the geotechnical consultant during construction should not relieve the contractor of his primary responsibility to perform the work in accordance with the specifications. This report is issued with the understanding that it is the responsibility of the Owner, or of his representative, to ensure that the information and recommendations contained Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 21 This report is issued with the understanding that it is the responsibility of the Owner, or of his representative, to ensure that the information and recommendations contained herein are brought to the attention of the Architect and Engineer for the project and incorporated into the plans, and the necessary steps are taken to see that the Contractor and Subcontractors carry out such recommendations in the field. Bagahi Engineering Inc. SUBSURFACE EXPLORATION _0 r4 WAL-4, PIP r- --Now- wAww I ¢wt , ti 0: OAe V-- Yhl I {roN Ca a tl v,� 7A -"fp-5 ly »r GPO�, V10r 'wog.K, -,nwV. 0460 o "ve,� wl: sw 4t q111-140"vo-IMCOX, k? NOT TO SCALE ENGINEEPdNG INC. ,OVED BY: DRAWN BY [REVISED ?LOT PLAN DRAWING NUMBER A-1 DEFINITION OF TERMS Primary Divisions Symbols Secondary Divisions COARSE- GRAVELS CLEAN GW Well graded gravels, gravel -sand mixtures, little or no GRAINED More Than GRAVELS fines. SOILS Half of Coarse (Less Than More Than Fraction Is 5% Fines) GP Poorly graded gravels or gravel -sand mixtures, little or Half of Larger Than no fines. GRAVEL WITH FINES GM Slily gravels, gravel -sand -silt mixtures, nonplastic Tines. Material Is Larger Than No. 4 Sieve GC Clayey gravels, gravel -sand -clay mixtures, plastic fines. SANDS CLEAN SW Well -graded sands, gravelly sands, little or no Tines. No. 200 Sieve Size More Than SANDS SP Poorly graded sands or gravelly sands, little or no fines. Halt of Coarse (Less Than 5% Fines) Fraction Is Smaller Than SANDS SM Silty sands, sand -silt mixtures, nonplastic fines. No. 4 Sieve WITH FINES Sc Clayey sands, sand -clay mixtures, plastic fines. FINE- SILTS AND CLAYS ML Inorganic silts and very fine sands, rock flour, silty or GRAINED LIQUID LIMIT IS clayey fine sands or clayey silts with slight plasticity. SOILS LESS THAN 50% More Than CL Inorganic clays of low to medium plasticity, gravelly Half of clays, sandy clays, lean clays, OL Organic silts and organic silty clays of low plasticity. Material Is Smaller Than No. 200 Sieve Size SILTS AND CLAYS LIQUID LIMIT IS GREATER THAN 50% MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts. CH I Inorganic clays of high plasticity, fat clays. OH Organic clays of medium to high plasticity, organic slits. HIGHLY ORGANIC SOILS Pt Peat and other highly organic soils. GRAIN SIZES SANG I GRAVEL SILTS AND CLAYS COBBLES BOULDERS FINE MEDIUM COARSE I FINE I COARSE 200 40 10 4 U.S. STANDARD SERIES SIEVE RELATIVE DENSITY Cohasionless Sands Blows/ft * Blow*" and Silts Veryloose 0-4 0-30 Loose 4-10 30-80 Medium dense 10-30 80-200 Dense 30-50 200-400 Very dense Over 50 Over 400 3/4" 3" 12" CLEAR SQUARE SIEVE OPENINGS CONSISTENCY Cohesive Soils Blows/tt* Blows/ft- Very soft 0-4 0-4 son 2-4 4-11 Firm 4-B 11-50 Stiff 8-16 50-110 Very stiff 16-32 110-220 Hard Over 32 Over 220 * Blows/foot for a 140-pound hammer falling 30 Inches to drive a 2-Inch O.D., 1-3/8-inch I.D. Split Spoon sampler (Standard Penetration Test). *" Blows/foot for a36-pound hammer falling 24Inches to drive a 3.25 O.D„ 2,41 I.D. sampler (Hand Sampling). Blow count convergence to standard penetration test was done in accordance with Fig. 1.24 of Foundation Engineering Handbook by H.Y. Fang, Van Nostrand Reinhold, 1991. Key to Sample Types: R=Ring Sample S=Split Spoon B=Bulk JOB NO.: I DATE: I FIGURE: A-2 KEYLOGSA-2 DATE OBSERVED: 4/16109 LOG OF BORING NO. B-1 LOCATION: See Plot Plan LOGGED BY: SG METHOD OF DRILLING: 4" Solid Auger GROUND EL.: DRILLING CONTRACTOR: - HAMMER 361bs. FALLING: 24 inches This log is part of the report prepared by Bagahi Engineering Inc. Depth Depth Soil Sample Blows/ Field Field and should be read together with the report for complete Type Type Foot Moist Density interpretation. The summary applies only at the location of this data in log is N (pco boring and at the time of drilling. The contained this a simplification of actual conditions encountered. Grass 1- B 5.3 0 - 2' — Light brown fine silty SAND, slightly moist 2- R 80 9.9 121.1 @ 2' —Brown sandy SILT, moist 3- 4- R 100 8.1 120.4 5- B 7.5 @ 5'- Orange brown silty SAND, moist, dense 6- @ 6' - Refusal, end of drilling 7 No Seepage 8- No Cave-in No Groundwater 9- 10- 11- 12- 13- 14- 15- 16- 17- 18- 19- 20- 21- 22- JOB NO.: 198n-200-00 2306 Margaret FIGURE: A-3 SHEET 1 OF 1 BAGAHI ENGINEERING INC. DATE OBSERVED: 4/16/09 LOG OF BORING NO. B-2 LOCATION: See Plot Plan LOGGED BY: SG METHOD OF DRILLING: 4" Solid Auger GROUND EL.: DRILLING CONTRACTOR: - HAMMER: 36 lbs. FALLING: 24 inches This log is part of the report prepared by Bagahi Engineering Inc. Depth Soil Sample Blows/ Field Field and should be read together with the report for complete (ft.) Type Type Foot Moist Density interpretation. The summary applies only at the location of this (%) (pcD boring and at the time of drilling. The data contained in this log is a simplification of actual conditions encountered. Grass 1- B 8.1 0 — 1 %:' — Light brown fine SAND, slightly moist 2- R 65 11.1 122.7 @ 1 1/2' —Brown sandy SILT, moist, some 3- plasticity 4- R 60 8.8 119.8 @ 4'- Orange brown silty SAND, moist, medium dense 5- 6- R 80 11.7 116.3 7- 8- 9- 10- B 13.4 @ 10' - Refusal, end of drilling 11- No Seepage No Cave-in 12- No Groundwater 13- 14- 15- 16- 17- 18- 19- 20- 21- 22- JOB NO.: 198n-200-00 2306 Margaret FIGURE: A-4 SHEET 1 OF I BAGAHI ENGINEERING INC. ' "1 D► LABORATORY TESTING Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 LABORATORY TESTING IuT(init II—13DR&I110 Moisture Density determinations were made on ring samples obtained from drilling. Moisture content tests were performed on bulk samples. Test results are presented in the boring logs. SULFATE A sulfate test was performed on a representative sample of the on -site soils. The laboratory standard used was California 417 A. The test results show a low sulfate content of less than 0.1 percent. DIRECT SHEAR A direct shear test was performed on a sample of the near -surface soils. The apparatus used is in conformance with the requirements outlined in ASTM: D3080. The test specimen, 2.4 inches in diameter and 1-inch in height, was subjected to simple shear along a plane at mid -height after allowing time for pore pressure dissipation prior to application of shearing force. The sample was saturated prior to shear under various normal loads. The sample was sheared at a constant rate of strain of 0.05 inches per minute. Shearing of the specimen was continued until the shear stress became essentially constant, decreased or until a deformation of approximately 10 percent of original diameter had been reached. The post -peak shear stress values were plotted versus applied normal stress, and a best -fit straight line through the plotted points was drawn to determine the cohesion and the angle of the internal friction parameters. The direct shear test result is graphically presented in Direct Shear Test Plot. CONSOLIDATION A consolidation test was performed on a sample of near -surface soils in accordance with procedure outlined in ASTM D:2435. The sample was placed in a consolidometer and loads were applied incrementally in geometric progression. The sample, 2.4 inches in Bagahi Engineering Inc. Mr. and Mrs. Brian Ellerbroek Project: Single Family Residence Project No: 198n-200-00 / April 22, 2009 diameter and 1-inch in height, was permitted to consolidate under each load increment until primary consolidation was essentially complete. The percent consolidation for each load cycle was recorded as the ratio of the amount of vertical compression to the original 1-inch height. Hydro -consolidation (collapse) and expansion characteristics were also evaluated by monitoring the change in volume with the addition of water while specimen was confined under and in -situ constant normal stress. The consolidation test results are graphically presented in the Load Consolidation Test Plot. EXPANSION INDEX An expansion index test was performed on a representative sample of remolded soil from Drill Hole B-1 from 0 to 3 feet. The test was performed in accordance with ASTM Standard D-4829-95 and indicated an expansion index of 75 corresponding to a medium expansion potential. _ Bagahi Engineering Inc. PROJECT: 23D6 Margaret Cir. Boring No: B-2 Depth: -2' Sample Saturation @: 16DO 0 2 161 e 4 z 0 a o s 0 0 z 0 o 6 7 8 9 10 10D CONSOLIDATION TEST LOAD, psf m DIRECT SHEAR TEST SUM u N Q 2500 N N N m 2000 N t rr ... wa 0 Normal Stress, psf Project: 2306`Mar6arete Cohesion, c = 1000psf Project No.: 198n=2-00Friction Angle = 100 Boring No.: B-2 Depth Elevation: 2 ft. Brown sandy -SILT Bagahi Engineering Inc.