HomeMy WebLinkAboutSTECKLER 05 C4 Geotechnical Recommendations � J C
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Exterior Slabs-on-grade(Hardscape) Trench Backfill geoterbniral Z
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April 5,2019 applications
Concrete slabs cast against properly compacted fill materials shall be a The on-site soils may be used as trench backfill provided they are screened of 1011SUIlaaIs Project No.IH183.1 (/� � Z LLJ
minimum of 4 inches thick(actual)and reinforced with No. 3 rebar at 18 inches rock sizes over 4 inches in dimension and organic matter. Trench backfill Site: Pr000sed Single Family Dwelling:132 South Bayfront r 1 j F ~
on center in both directions. The reinforcement shall be supported on chairs to should be compacted in uniform lifts not exceeding 6 inches in compacted Newport Beach(Balboa Island),Califomia [� �J =
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insure positioning of the reinforcement at mid center in the slab. thickness)by mechanical means to at least 90 percent relative compaction � C) M
Executive Summary
(ASTM: D 1557). ~-� N Z
Control joints should be provided at a maximum spacing of 8 feet on center in Based on our geotechnical study of the site,our review of available reports and literature and our Z __ _ ^ O
two directions for slabs and at 6 feet on center for sidewalks. Control joints are Geotechnical Parameters experience,it is our opinion that the proposed residential development is feasible from a geotechnical V U
intended to direct cracking. standpoint. There appear to be no significant geotechnical constraints on-site that cannot be mitigated by _J U
proper planning,design,and utilization of sound construction practices. The engineering properties of the L L.
The following Geotechnical parameters may used in the design of the proposed m ON <
soil and native materials,and surface drainage offer favorable conditions for site re-development. -� af � =
Expansion or felt joints should be used at the interface of exterior slabs on structure(also, see"Liquefaction Analysis"section,above): (D Z
grade and any fixed structures to permit relative movement. The following key elements are conclusions confirmed from this investigation: Z <
Foundation Design
Some slab cracking due to shrinkage should be anticipated. The potential for A review of available geologic records indicates that no active faults cross the subject property. Z Z
the slab crackingmay be reduced b careful control of water/cement ratios. Structures on properly compacted fill may be supported b conventional, The site is located in the seismically active Southern California area,and within 2 kilometers of the I-IJ <
y Y p p Y p y pp y Type B Newport-Inglewood Fault. As such,the proposed development shall be designed in N Z
The contractor should take appropriate curing precautions during the pouring of continuous or isolated spread footings. All footings should be a minimum of 24 accordance with seismic considerations specified in the 2016 California Building Code(CBC)and
concrete in hot weather to minimize cracking of slabs. inches deep(measured in the field below lowest adjacent grade). Footing the City of Newport Beach requirements.
widths shall me an minimum 15 inches and 18 inches for interior cross beams Foundation specifications herein include added provisions for potential liquefaction on-site per City
Surface Drainage and perimeter footings respectively. policy CBC 1803.11-12.
Surface drainage shall be controlled at all times. Positive surface drainage As stated above,additionally,to further reduce the effects of the thin zones of SUMMARY OF RECOMMENDATIONS
should be provided to direct surface water away from structures and toward the potentially liquefiable soils,the building slab shall include 15"wide by 24"deep Design Item Recommendations
street or suitable drainage facilities. Ponding of water should be avoided interior grade beams to be reinforced with two No.5 rebars(two at the top and Foundations: IN
adjacent to the structures. Recommended minimum gradient is 2 percent for two at the bottom). The cross beam locations shall be determined by the Footing Bearing Pressure: 1,750 psf-building,continuous;2,250 psf-pad footings
unpaved areas and one percent for concretelpaved areas. Roof gutter structural engineer. Passive Lateral Resistence: 250 psf per foot
Perimeter Footing Widths: min.15 inches with two No.5 bars top and bottom
discharge should be directed away from the building areas through solid PVC Perimeter Footing Depths: min.24 inches below lowest adjacent grade
pipes to suitable discharge points. Area drains should be provided for planter At this depth(24 inches)footings founded in fill materials may be designed for Interior Slab Beams: min.24 inches below lowest adjacent grade
areas and drainage shall be directed away from the top of slopes. an allowable bearing value of 1,750 and 2,250 psf(for dead-plus-live load)for Coefficient of Friction: 0.30
continuous wall and isolated spread footings,respectively. These values may Mat Slab(Optional): min.12 inches with thickened edges(+6 inches)
Review of Plans be increased by one-third for loads of short duration, including wind or seismic with no.5 bars @ 12"o.c.each way,top and bottom
forces. Soil Expansion: Non-Expansive Silty Sands
Soil Sulfate Content: Nggligible
The specifications and parameters 6utlined in this report shall be considered Building Pad Over-Excavation: min.'2'%ft.below existing grade,scarify bottom
minimum requirements and incorporated into the Grading,and Foundation Reinforcement requirements may be increased if recommended by the project Sandy Soil Max.Density: 117.0 pcf @ 10.5%Opt.Moisture
Plans if applicable. This office should review the Plans when available. If structural engineer. In no case should they be decreased from the previous
approved,the geotechnical consultant shall sign/stamp the applicable Plans recommendations. Building Slab:
from a geotechnical standpoint. • Concrete slabs cast against properly compacted fill materials shalt be a minimum of 5 inches
thick(actual)and reinforced with No.4 rebar at 12 inches on center in both directions.
Mat Foundation Design(Optional) Dowel all footings to slabs with No.4 bars at 24 inches on center.
Concrete building slabs shall be underlain by 2"clean sand,underlain by a min.15 mil thick
PRE-CONSTRUCTION MEETING Due to anticipated high tide waters and cohesionless sands during construction, moisture barrier,with all laps sealed,underlain by 4"of%-inch gravel(capillary break).
a mat slab foundation system is a recommended option. Mat slabs founded in Seismic Values(per CBC 2016,ASCE 7-10.
It is recommended that no clearing of the site or any grading operation be performed without IP )'
compacted fill or competent native materials may be designed for an allowable Site Class Definition(Table 1613.5.2) D
the presence e a representative e this office. ad on site pre-grading meeting should be bearingvalue of 2,250 psf for dead-plus-live load . These values may be
arranged between the soils engineer and the grading contractor prior to any construction. ( p ) Y Mapped Spectral Response Acceleration at 0.2s Period, Sa 1.739 g
increased by one-third for loads of short duration, including wind or seismic Mapped Spectral Response Acceleration at 1s Period, S, 0.642 g
forces.The actual design of the foundation and slabs should be completed by Short Period Site Coefficient at 0.2 Period, Fa 1.0
Long Period Site Coefficient at 1s Period, F, 1.5 ]AN J.N.HARRI50N,ARCHITECT
Adjusted Spectral Response Acceleration at 0.2s Period, Sas 1.739 g hereby expressly reserves its common law copyright
and other property rights in these plans.These plans are
132 South Bayfront,Newport Beach(Balboa Island),CA 132 South Bayfront,Newport Beach(Balboa Island),CA Adjusted Spectral Response Acceleration at is Period, S., 0.963 g not to be reproduced,copied or changed in any form
Soils Report-Steckler Residence Soils Report-Steckler Residence Design Spectral Response Acceleration at 0.2s Period, Sos 1.1609 whatsoever,nor are they to be assigned to a third part4,
Project No.Hil83.1 Project No.IH183.1 Design Spectral Response Acceleration at is Period, Sp, 0.642 g without the express written perml55ion and consent P
AN J.N.HARR50N,ARCHITECT.
April 5,2019 _ April 5,2019 14 PGAm=0.723 g
375-C Monte Vista Avenue•Costa Mesa,CA 92627•(949)642-9309•FAX(949)642-1290
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the structural engineer. tolerable amounts. The above specifications eliminate the use of piles and
GEOTECHNICAL OBSERVATION AND TESTING DURING CONSTRUCTION associated construction vibrations and groundwater displacement induced by O
MIN.DESIGN ITEM RECOMMENDATIONS caisson drilling or pile-driving. If the above specifications are incorporated,the
We recommend that a qualified geotechnical consultant be retained to provide geotechnical Mat foundations: proposed structure shall be stable and adequate for the intended uses and the 1
engineering services,including geotechnical observation/testing,during the construction phase allowable bearing pressure: 2,250 psf proposed construction will not adversely impact the subject or adjacent �'
of the project.This is to verify the compliance with the design,specifications and or passive lateral resistance: 250 psf per foot 0
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recommendations,and to allow design changes in the event that subsurface conditions differ mat slab thickness: min.12 inches with thickened edges(+6 inches) properties. 'p1
steel reinforcement: no.5 bars @ 12"o.c.each way,top and bottom
from those anticipated. coefficient of friction: 0.30 Other Geologic Hazards N
Geotechnical observations/testing should be performed at the following stages: Modulus of Subgrade Reaction: ks=90 Ibs/in3
4-1
• During ANY grading operations,including excavation,removal,filling,compaction, Other geologic hazards such as Iandsliding,or expansive soils, do not appear to
and backfi ati etc. Reinforcement requirements may be increased if recommended by the project be evident at the subject site. w
• After excavations for footings thickened edges)and/or grade beams verify the structural engineer. In no case should they be decreased from the previous
adequacy of underlying materials, CONCLUSIONS
• After pre-soaking of new slab sub-grade earth materials and placement of capillary recommendations. O �
break,plastic membrane,prior to pouring concrete. Based on our geotechnical study of the site,our review of available reports and
• During backfill of drainage and utility line trenches,to verify proper compaction. Interior Slabs-on-grade -conventional O <
literature and our experience, it is our opinion that the proposed improvements at the 2
• When/if any unusual geotechnical conditions are encountered. site are feasible from a geotechnical standpoint. There appear to be no significant
• Prior to slab pours to ensure proper Subgrade compaction and moisture barriers. Concrete slabs cast against properly compacted fill materials shall be a Z
minimum of 5 inches thick(actual)and reinforced with No.4 rebar at 18 inches geotechnical constraints on-site that cannot be mitigated by proper planning, design, w
Please schedule an inspection with the geotechnical consultant prior to the on center in both directions. The slabs shall be doweled into the footings using and utilization of sound construction practices. The engineering properties of the soil z
No.4 bars at 24 inches on center. The reinforcement shall be supported and native materials,and the surface drainage offer favorable conditions for site re- Q on
pouring of all interior and exterior slabs, pp �
chairs to insure positioning of the reinforcement at mid-center in the slab. development.
Interior slabs shall be underlain by 2 inches of clean sand over a min. 15 mil 3
RECOMMENDATIONS
thick,puncture-resistant plastic sheeting (e.g."Stego Wrap"),with all laps 73
LIMITATIONS sealed,over 4 inches of%-inch gravel(see"Capillary Break"specifications, Q
below). The following sections discuss the principle geotechnical concerns which should be
The geotechnical services described herein have been conducted in a manner consistent with the level of considered for proper site re-development.
care and skill ordinarily exercised by members of the geotechnical engineering profession practicing
contemporaneously under similar conditions in the subject locality.Under no circumstance is any Some slab cracking due to shrinkage should be anticipated. The potential for Earthwork
warranty,expressed or implied,made in connection with the providing of services described herein.Data, the slab cracking may be reduced by careful control of water/cement ratios. +,
interpretations,and recommendations presented herein are based solely on information available to this
The contractor should take appropriate curing precautions during the pouring of
office at the time work was performed.EGA Consultants will not be responsible for other parties' Grading and earthwork should be performed in accordance with the following
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interpretations or use of the information developed in this report. concrete in hot weather to minimize cracking of slabs. We recommend that a
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slipsheet(or equivalent)be utilized if crack-sensitive flooring is planned directly recommendations and the General Earthwork and Grading Guidelines included
Appendix C. It is our understanding that the majority of grading will be limited 4-1The interpolated subsurface conditions should be checked in the field during construction by a on concrete slabs. All slabs should,be designed in accordance with structural v
representative of EGA Consultants. We recommend that all foundation excavations and grading considerations. to the re-grading of the building padfor the proposed construction. In general,it =3
operations be observed by a representative of this firm to ensure that construction is performed in is anticipated that the removal of the upper 21/2 feet(plus 6 inches of N4-1
accordance with the specifications outlined in this report. scarification)within the building footprint(slab-on-grade portion)will require th
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Capillary Break Below Interior Slabs removal and recompaction to prepare the site for construction.The removals /�
We do not direct the contractor's operations,and we cannot be responsible for the safety of others. The should be accomplished so that all fill and backfiil existing as part of the �/ v
contractor should notify the owner if he considers any of the recommended actions presented herein to be In accordance with the 2016 California Green Building Standards Code Section o O
unsafe. 4.505.2.1,we provide the following building specification for the subject site previous site use and demolition operations are removed. IN
(living area and garages slabs): 01� 73
Where feasible,the limits of the pad fill shall be defined by a 3 foot envelope 0
encompassing the building footprint. Care should be taken to protect the N
Concrete building slabs shall be directly underlain by 2 inches of washed I-- Q S_sand,underlain by a min. 15 mil thick visqueen moisture barrier(e.g."Stego adjacent property improvements. n -
Wrap")with all laps sealed, underlain by 4 inches of 3/,inch gravel. We do A minimum one foot thick fill blanket should be placed throughout the exterior !�1
not advise placing sand directly on the gravel layer as this would reverse the effects of vapor retardation(due to siltation of fines). improvements(approaches, parking and planter areas). The fill blanket will be
132 South Bayfront,Newport Beach(Balboa Island),CA 132 South Bayfront,Newport Beach(Balboa Island),CA 132 South Bayfront,Newport Beach(Balboa Island),CA r '
Soils Report-Steckler Residence Soils Report-Steckler Residence Soils Report-Steckler Residence
Project No.III 183.1 Project Nc.I11183.1 Project No.IH 183.1
April 5,2019 18 April 5,2019 15 April 5,2019 12 l
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The above specification meets or exceeds the Section 4.505.2.1 requirement.
achieved by re-working(scarifying)the upper 12 inches of the existing grade.
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Remedial Grading-Soil Cement
Cement Type for Concrete in Contact with On-Site Earth Materials
Due to in situ granular sands,we recommend approximately four(4)pallets(35
Concrete mix design should be based on sulfate testing with Section 1904.2 of bags dry mix, each weighing 94 pounds and approximately 1.33 cubic yards)of \^V/
the 2016 CBC(in the event of soil import,soils shall be tested a specified Portland cement be blended into the newly-placed fill. The first application of
accordingly). Preliminary laboratory testing indicates the site soils possess the Portland Cement shall be placed on the bottom of the scarified over- O
negligible sulfate exposure. excavation(s). This option may be eliminated or reduced if suitable import fills
ACI 318 BUILDING CODE-Table 19.3.1.1 are trucked-in.
REQUIREMENTS FOR CONCRETE EXPOSED TO SULFATE-CONTAINING SOLUTIONS r i 1
Site Preparation w
Sulfate Water soluble Sulfate(504)in Cement Type Maximum wafer- Minimum
Exposure sulfate(504)in soil water,ppm cementitious material normal-weight
(301 percent by weight ratio,by weight,normal and lightweight Prior to earthwork or construction operations,the site should be cleared of
weight concrete concrete'psi surface structures and subsurface obstructions and stripped of any vegetation
Negligible 0.00 s So,<0.10 0<s04<150 ------ - in the areas proposed for development. Removed vegetation and debris should
Isil then be disposed of off-site. A minimum of 2'/z feet of the soils below existing
Moderate 0.10<SO4<0.20 150<SO4<1500 II,IP(Ms), 0.50 4000 grade will require removal and recompaction in the areas to receive building pad
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[sz] (MS)( fill. Following removal and scarification of 6 inches,the excavated surface
MS),
I(SM)(Ms) should be inspected by the soils engineer or his designated representative prior
Severe 0.z0_SO4<z.00 1500<So4< v 0.45 4500 to the placement of any fill in footing trenches. Holes or pockets of
(s3j 10,000 undocumented fill resulting from removal of buried obstructions discovered
Very Severe SO4>2.00 So4>10,000 vplus 0.45 4500 during this inspection should be filled with suitable compacted fill.
IS4, poaalan IJOB # 5TEGKLER
Fills
As a conservative approach,and due to the marine environment,we
recommend cement with a minimum strength f'c of 3,000 psi be used for The on-site soils are suitable for reuse as compacted fill, provided they are free DRAWN BY pdw
concrete in contact with on-site earth materials. of organic materials,debris,and materials larger than four(4)inches in
diameter. After removal of any loose,compressible soils,all areas to receive fill
Settlement and/or other surface improvements should be scarified to a minimum depth of PLOT DATE h/�/201Q
12 inches, brought to at least 2 percent over optimum moisture conditions and
Utilizing the design recommendations presented herein,we anticipate that the compacted to at least 90 percent relative compaction(based on ASTM: D RI VISION BY DATE
majority of any post-grading settlell7ent will occur during construction activities. 1557). If necessary, import soils foll near-surface fills should be predominately
We estimate that the total settlement for the proposed structure will be on the granular, possess a very low expansion potential,and be approved by the
order of 1 inch. Differential settlement is not expected to exceed 1 inch in 40 geotechnical engineer.
feet. These settlement values are expected to be within tolerable limits for
properly designed and constructed foundations. Lift thicknesses will be dependent on the size and type of equipment used. In
general,fill should be placed in uniform lifts not exceeding 6 inches. Placement
Lateral Load Resistance and compaction of fill should be in accordance with local grading ordinances
under the observation and testing of the geotechnical consultant. We U
Footings founded in fill materials may be designed for a passive lateral bearing recommend that fill soils be placed at moisture contents at least 2 percent over
pressure of 250 pounds per square foot per foot of depth.A coefficient of optimum(based on ASTM: D 1557).
friction against sliding between concrete and soil of 0.30 may be assumed. p
We recommend that oversize materials(materials over 4 inches)should they be LU
encountered, be stockpiled and removed from the site.
132 South Baytrcnt,Newport Beach(Balboa Island),CA 132 South Bayfront,Newport Beach(Balboa Island),CA
Soils Report-Steckler Residence Soils Report-Steckler Residence
Project No.I11I83.1 Project No.Hil83.1
April 5,2019 16 April 5,2019 :3 LA
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