HomeMy WebLinkAboutCDP 2017-0023; 3913 SHERIDAN PLACE; GEOTECHNICAL INVESTIGATION; 2017-03-27Ct)72or}- 002-3
Geotechnical Investigation
Proposed Single-Family Residence
3913 Sheridan Place
Carlsbad, California
(APN 206-042-47-00)
CDP 2017-0023
DWG 505-7A
GR2017-0041
March 27, 2017 RECEI\7'1ED
OCT 10201?
LAND DEVELOPMENT
ENGINEERING -
Prepared For:
Prophet Solutions, Inc.
Mr. Rod Boone
5845 Avenida Encinas, Suite 138
Carlsbad, California 92008
Prepared By:
SNSGEOTECHNICAL SOLUTIONS, INC.
5931 Sea Lion Place, Suite 109
Carlsbad, California 92010
Project No. GI-17-02-107
GEOTECHNICAL SOLUTIONS, INC.
Consulting Geotechnical Engineers & Geologists
5931 Sea Lion Place, Suite 109
Carlsbad, California 92010
760-602-7815
smsgeosoLincgmaiLcom.
Project No. GI-17-02-107
March 27, 2017
Prophet Solutions, Inc.
Mr. Rod Boone
5845 Avenida Encinas, Suite 138
Carlsbad, California 92008
GEOTECHNICAL INVESTIGATION, PROPOSED SINGLE-FAMILY RESIDENCE,
SHERIDAN PLACE, CARLSBAD, CALIFORNIA. (A.P.N. 206-042.47-00)
Pursuant to your request, SP1S Geotechnical Solutions, Inc. has completed the attached Geotechnical Investigation Report for the proposed single-family residential development at the
above-referenced property.
The following report summarizes the results of our subsurface exploratory test borings, field in-situ testing and. sampling, laboratory testing, engineering analysis and provides conclusions and recommendations for the proposed new development, as understood. From a geotechilical engineering standpoint, it is. our opinion that the planned single-family residential development at
the project property is feasible, provided the recommendations presented in this report are
incorporated into the design and construction of the project.
The conclusions and recommendations provided in this study are consistent with the site indicated geotechnical conditions and are intended to aid in preparation of final plans and allow more accurate estimates of construction costs.
If you have any questions or need clarification, please do not hesitate to contact this office. Reference to our Project No. GI-17-02-107 will help to expedite our response to your inquiries.
We appreciate this opportunity to be of service to you.
Nj1PINGeotechnical Solutions, Inc.
H!. PROPOSED DEVELOPMENT
. I I IV. FIELD INVESTIGATION ............ ................................. ............. ..................2
I V. GEOTECHNIC AL-CONDITIONS .............................................................................2
Earth Materials...............................................................................2
Groundwater and Surface Drainage .................................... .........................3 I C. Faults / Seismicity.....................................................................................3
D. Seismic Ground Motion Values.......................................................................5
- 11' (t.ninnh. 1i-hi7r,1€ ,zn,i Inno SthiHtv
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F Field and Laboratory Tests and Test Results 6
VI SITE CORROSION ASSESSMENT 9
VII STORMWATER BMPs 10
VIII CONCLUSIONS 11
IX RECOMMENDATIONS 13 A Grading and Earthworks
j3 B Footings and Slab-on-Grade Foundations 17 C Soil Design Parameters 18 D Exterior Concrete Slabs and Flatworks 19 E Proposed Spa . 20 F Pavement Design 21 G General Recommendations 23
X. GEOTECHNICAL ENGINEER. OFRECORD(GER)
XL: LIMITATIONS 26
FIGURES.
Regional Index Map
* 1 Approximate Geotechmcal Map
. 2
Boring Logs: ..... ........••...•..• .........i*t**.ó*-*:**t .................**S•,OS • 35 Fault-Epicenter Map 6 Sieve Analysis :.....................
Typical Isolation Joints and Re-Entrant Corner Reinforcement 8 Typical Permeable Paver Detail 9 Typical Retaining Wall Back Drainage Detail
. 10
APPENDIX
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The project property investigated herein consists of a relatively level, nearly rectangular-shaped
vacant parcel, located within a developed residential cul-de-sac. south of Tamarack Avenue west of
Interstate 5 Freeway and within the limits of the City of Carlsbad. The approximate property
location is shown on a Regional Index Map attached to this report as Figure 1. The approximate site
coordinates are 33.1499°N latitude and -ll7.3394'\V longitude.
We understand that the project property is planned to support a single-family residence, and ,a. detached accessory dwelling unit with the associated structures and improvements. Consequently,
the purpose of this investigation 1,was to evaluate the soil and geotechnical conditions at the project
property and to ascertain their influence upon the planned new development. Exploratory test
borings, soil/rock sampling, laboratory testing, and engineering analysis were among the activities
conducted in conjunction with this effort, which resulted in the remedial grading and foundation
recommendations presented herein.
H. SITE DESCRIPTION
I An Architectural Site Plan prepared by Andrew Carlos Architect, dated March 10, 2016, that depicts
the planned development is reproduced and attached herein as an Approximate Geotechnical Map,
I Figure 2.
in gcncral, the: study property and surrow ding areas.are characterized by relatively 'level..: sUiiaCCs I near the adjacent Sheridan Place street grades, which bounds the property along the eastern margin. Developed residential lots neighbor the property on the north, south and west sides The property, ' is covered with a thick growth of native grasses Existing surface drainage at the site is not well
defined, however, neither ponded water nor excessively moist to wet ground surface conditions were
noted at the titheiofou±:i:fie1diiivetigations.
I Mli PROPOSED DEVELOPMENT
I 'c1Prne1t is shown on the enclosed Appro ate:Ge.techthcal Map, Figure 2. As shown, 4,2-story main residence is planned on the eastern portions of the lot, while a detached
accessory dwelling unit will occupy the property on the northwest corner. Associated improvements
I included an access driveway off of Sheridan Place, .a .spa on the southwest corner of the lot and
underground utilities
GeOltecbflical Investigation, Proposed Single-Family Residence March 27, 2017 Sheridan Place,, Carlsbad, California (A P N 206-04247-00) Page 2
Significant ground modifications or the creations of large.newt graded embankments are not
anticipated in connection with the planned site redevelopment However, minor or fine grading
efforts are expected to establish level pad grades and achieve final design surfaces The majority of
site earthwork operations related to building pad development are expected to consist of remedial
grading and foundation sOil:preparatiOn.
Detailed foundation and construction plans are not yet available, However, conventional wood-
frame with exterior stucco building type construction supported on shallow stiff, concrete footings
and slab-on-grade floor foundations are anticipated.
IV. FIELD INVESTIGATION:
Subsurface conditionsat the project site were chiefiyevahiated by reviewing pertinent geologic maps and literature and by the excavation of three exploratory test borings drilled with ,.a mini track-mounted hollow stem auger rotary drill rig Borings were logged by our project geologist, who also
supervised in-situ testing and the collection of representative soil samples at selected intervals for
subsequent laboratory testing Boring locations are shown on the enclosed Figure 2 The logs of the
exploratory borings are attached to this report, as Figures 3, 4 and S. Laboratory test results and engmeermg properties of selected representative soil samples are summarized in following sections
V.. :GEOTECHNICAL. CONDITIONS
The project site is underlain at shallow depths by natural TeacDepitthatarewidely.exposed
along coastal areas of Carlsbad Site surfaces mostly appear to consist of natural to disturbed terrain
Instability which could preclude the planned development is not in evidence The following earth
materials were recognized:
A. Earth Materials
I Terrace Deposits (Qt): Pleistocene age Terrace Deposits, typical of local coastal
underlay the property at a relatively shallow depth As exposed in our exploratory borings,
I the Terrace Deposits typically consist of tan to red brown colored silty fine to coarse grained
sandstone units that were generally found in weathered conditions near the upper exposures
becoming dense to very dense with depth Underlying Terrace Deposits also included
i occasional pebbles.
The underlying.:dense to very dense Terrace Deposits below the upper weathered zone. will
I adequately support newfillsi Structures, and improvements.
Topsoil (Qs) A relatively shallow section of undifferentiated topsoil/disturbed natural
I ground mantles site Terrace Deposits Based on our subsurface explorations, site
topsoil/disturbed natural-ground mantle is typically on the order of 2½ feet thick, at the
exposed locations, and chiefly consists of dark brown silty fine to medium sand that occurs
I in a moist to very moist and loose to very loose condition overall.
Sheridan Place, Carlsbad, CaJifornia.:(AP.N. 206-042747-00) Page..3
.Site-.existing stficiaI.. topsoil/disturbed natural ground deposits *d .iipper. weathered
exposures of the underlying Terrace Deposits are not suitable for structural support in their, present condjtion,•and•shouild be.regraded asoutiined in following sections..
Detailed logs of the exploratory borings are provided in the attached to Boring Logs, Figures
3 thrQugiu: 5..
Groundwater and Surface Drainage
Subsurface water was not encountered in our test borings to the depths explored at the time
of our field explorations, and is not expected to impact the proposed newl development
However, like all developed properties, proper control of surface drainage is an important
factor in the continued stability of the future development and performance of planned new
buildings and associated site improvements Ponding of surface run-off near foundations
should not be allowed, and over-watering. of. .site vegetation should be avoided' Perimeter
surfaces 'should direct..run.-off"asvay.'front the building foundations and site,inpovements,..
Surface run-off should be properly captured and discharged into approved storm drainage
facilities as shown on the project approved plans
faults / Seismicity
Faults and other significant shear zones are not indicated on or near the proximity of the
project site
As with most areasin CalifOrnia, the San Diego rgiOn lies within aEseismi'cally active zone;
however, coastal areas of the county are characterized by low levels of seismic activity
relative to inland areas to the east During a 40-year period (1934-1974), 37 earthquakes were recorded in San Diego coastal areas by the California Institute of Technology. None
.of the recorded events exceeded a..Richter.magnitude:o'f 3.7, nor did any of the .eaithqu*es
generate more than modest ground shaking or significant damages Most of the recorded
events occurred along various offshore faults which characteristically generate modest
earthquakes.
Historically, the most significant earthqualce events that. affect local areas originate along:
well known, distant fault zones to the east and from the Coronado Bank Fault to the west
Based upon available seismic data compiled from California Earthquake Catalogs, the most
significant historical event in the area of the study site occurred in 1800 at an estimated
distance of 10.6 miles from the project area This event, which is thought to have occurred
along an offshore fault, was an estimated magnitude 6.5 earthquake with an estimated
bedrock acceleration value of :O. 151g at the project site
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GeotechnkaiInvcstigation, F ..Mard.I27,. 2017
The following list represents the most significant faults that routinely unpact the region The
estimated ground laccelerationjRKW compiled from the Digitized 'California 'Faults, (Computer Program EQFAULT VERSION 3 00 updated) typically associated with
respective faults are also tabulated
TABLE. .1
FAULT ZONE DISTANCE FROM SITE
MAXIMUM
PROBABLE
ACCELERATION (RMGA)
Rose Canyon Fault 4.6 miles 0.256g
Newport-Inglewood Fault 5.2 miles 0.240g
Coronado Bank Fault 20.8 miles 0.187g
Elsinore-Julian Fault 24.5 wiles 0.140g
The location of significant faults and earthquake events relative to the study site are depicted
on a Fault - Epicenter Map attached to this report as Figure 6
More rectly, the number of seismic events in the region appears to have increased in
frequency. Nearly 40 earthquakes of magnitude 3.5 or higher have been recorded in coastal
regions between January 1984 land August 1986. Most of the earthquakes are thought to
have been generated along offshore faults. For the most part, the recorded events remain
moderate shocks, which typically resulted in low levels of ground shaking to local areas. A
notable exception to this pattern was recorded on July 13, 1986 when an earthquake of
magnitude 5.3 shook the County coastal areas with moderate to locally heavy ground shaking
which resulted in $700,000 in damages, one fatality, and 30 peopled injured. The quake
ruptured along an offshore fault located approximately 30 miles southwest of the City of
Oceanside.
A serie of notable events. shook .th.Cpntyareas.with .a maximuinmagnitude 7.4 shockiñ,
the early morning of June 28, 1992 These quakes originated along related fault segments
of the San Andreas Fault approximately 90 miles to the north Local high levels of ground
shaking over an extended period of time occurred, however, significant damages to local
structures were not reported The increase in earthquake frequency in the region remains a subject of speculation among geologists, however, based upon empirical information and the
recorded seismic history of County areas, the 1986 and 1992 events are thought to represent
the highest levels of ground shaking which can be expected at the study site as .a result of
seismic activity.
Sheridan Place, Carlsbad, California (AJ'.N. 206042-47-00) Pagel:5
In recent years, the Rose Canyon Fault has received added attention from geologists The
fault is a significant structural feature in metropolitan San Diego which includes a series of
parallel breaks trending southward from La Jolla Cove through San Diego Bay toward the
Mexican border. Test trenches along the fault in Rose Canyon indicated that at .that 1octiön
the fault was last active 6,000 to 9,000 years ago More recent work suggests that segments
of the fault arc younger having been last active 1000 - 2000 years ago Consequently, the
fault has been classified as active and included within an Aiquist-Priolo Special Studies Zone
established by the State of California Furthermore, a more recentf study concluded that the
coastal region of San Diego may-experience earthquakes up to magnitudes 7.3 and 7.4
(Sahakian et al, 2017) This study used Newport-IngelwoodIRose Canyon fault offshore
Although, an earthquake of this magnitude has likely not occurred in the 1-00,000Y ars,
accor..ing to tiLe data,
Fault zones tabulated in the preceding table are considered the most likely to impact the
region around the study site during the lifetime of the project The faults are penodically
active, and capable of generating moderate to locally high levels of ground shaking at the
site. Ground separation caused by .eismic activity:is not expected at the property.
D. Seismic Ground Motion Values...
Seismiä ground motion values were evaluated as part ofthiS:lnveStigatiofl in accordance with
Chapter 16, Section 16113 of the 2013 California Building Code (CBC) and ASCE 7-10
Standard using the web-based United States Geological Survey (USGS) ground motion
calculator. Generated results including the Mapped (Ss, Si), Risk-Targeted Maximum
Considered Earthquake (MCER) adjusted for Site Class effects (SMs, SMI) and Design (Sos,
Sni) Spectral Acceleration Parameters as well as Site Coefficients (Fa, Fv) for short periods
(0.20 second) and 1,-sftond period, Site Class, Design and Risk-Targeted Maximum
Considered Earthquake (MCER) Response Spectrum, Mapped Maximum Considered
Geometric Mean (MCEG) Peak Ground Acceleration adjusted for Site Class effects (PGAM)
and Seismic Design Category based on Risk Category, and the seventy of the design
earthquake ground motion at the site are summarized in:.the enclosed Appendix.
E.. Geologic Hazards and Slope Stabifi
Geologic hazards are not presently indicated at the project site. Significant slopes are not
present at or within close proximity to the project property, nor are Ahere any planned in
conjunction with the proposed development The most significant geologic hazards at the
property will be those associated with ground shaking in the event of a major seismic event
Liquefaction or related ground rupture failures are not anticipated
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Geotechmcal Investigation, Proposed Single-Family Residence March 27 2017
I Sheridan Place, Carlsbad, California .A.P.N. 206-0424740)
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F. Field .and Laboratory Tats, and lest Results
I Earth deposits encountered in our exploratory test: excavation were closely examined, and
sampled for laboratory testing Based upon our test pit and field exposures site soils have
1 been grouped j to the following soil, type;
TABLE.2
Soil Type Descrip.tiu
'1 Dark brown :fine'to rnedium sand (Topsoil)
2E Tan to red-brown ne"tO coarse cohesinkss 'sand.,to.silty'sand..(Terrace.Deposits) . .
The following tests were conduôted in. support of' this, ':i'nvestigatic'n':
1. Standard .Penetratio' Tests: Standard penetratiOn..tests (SPT) were performed at the time of borehole drilling in accordance with ASTM standard procedure D-1586 using
rope and cathead The procedure consisted of a standard 51 MM outside diameter
sampler without liner, 457 MM in length and 35 MM in inside diameter driven with a 140-pound hammer, dropped 30 inches using 5400t long AW drill rods The bore hole
was 200 MM (8 inches) in diameter and drill fluid or water was not necessary to aid
drilling. The test results are indicated at the corresponding locations on the attached
Boring Logs.
:2.. Grain Size Analysis: Grain size analysis was perfOrmed ona.reprcscntative sample of
Soil Types I and 2:,, The test results are provided,in Table .3 below and graphically
presented in the attached IFigure 7.
TABLE 3
Sieve Size 1 I " 1 %" #4 010 1 #20 440 #100 I #200
Location Soil Type: Percent Passing
B-1@3' 2 10 100 .H100 .. 100 100 99 88 9 31
B-i @9" . 2 10.0 100 100 100 100 46 18 . 13
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10
B-l@i5' 2 1001. 95. 92 98 75 51 13 7
3. Maximum flry Density and Optimum Moisture Content: The maximum dry density and optimum moisture content of Soil Type 2 was determined in accordance with ASTM
D-1557. The.resultsareprcsented in Table 4.
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II Soil Maxi.uuri Dry Optimum Moisture II Location LL ..
Type Density(Tut-pcf content op-%)
II B-1@3' 7-2 . 129 1 10
I 4 Unit Weight & Moisture Content Tests In-place dry density and moisture content of
representative soil deposits beneath the site were determined from relatively undisturbed
ring samples using the Direct Measurement test method (Method B) in accordance with ' ASTM D7263, and Water Content of Soil and Rock by Mass test method in accordance
with ASTM D22 16. The test results are presented in Table 51 and tabulated on the
attached Boring Logs at corresponding locations I TABLE ,5
Sample Soil Field Moisture Field Dry Max. Br) In Place Degree of
Saturatio Location Type Content Density Density Relative
(cA-%) (Td-pcl) (Tm-pet) Compaction S(/o)
B-1@3 2 11 1237 129 96 79
B-1@6 2 4 1158 129 90 23
6 129 -
B-i @ 15' 2
B-2@25' 2 10 1168 129 91 63
B-2@5'(2) 2 6 104 129 81 25
2 4 - 1129
B;-I,.@ 15' 2 6 - 129 Sample Disturbed -
B-3%4' 2 9 - .1117 129 91 58
B3.@7u)12 4 - 129
B-3@10'(I) 2 6 - 129 - -
(1) SPT Sample
(2) Sample May Somewhat Be Disturbed
Assumptions and Relationships
In-Place Relative Compaction = (Td - Tm) X 100
Gs =. 270
S=(w Gs) +e
Soil
(a
Sample Molded Degree of Final Initial Dr
. -Measured El
- Location Type
.Oli Saturation co Density -.
(%) (PCF) Saturation
{ B-2 .5' 8 [ 47 15 J 115.6 on plastic Non-expansive
() moisture content in percent.
E150 Elmeas - (50 - Smeas) ((65 + Elmeas) (220 - Smeas))
Expansion Index (El) Expansion Potential
0-20 Wry LOW 21-50 Low
51-90 Medium
91 - 130 High
)130 Vezy}ligh
6.. Direct Shear Test: .Qne:di.ect shear test was performed on arepreseative.sample.cf Soil Type 2 in substantial accordance with ASTM 13080 The prepared specimen was
soaked overnight, loaded with normal loads of 1, 2, and 4 kips per square foot
respectively, and sheared to failure in an undrained condition The test result is presented
iim Table 7
TABLE :7
Sample Soil Sample Wet Angle of Apparent
Location Type Condition Density mt. Fric. Cohesion
(Twp.c1) -Deg.) (c-psi)
B-i @ 3' J.21 Remo1dd to 90% of Yin @ % wopt 1294 j 34 [ 180
7. pH_ and Resistivity_Test; pH and resistivity of a representative sample of Soil Type 2
was determined using "Method for Estimating the Service Life of Steel Culverts," in
accordance with the California Test Method (CTM) 643. The test result is tabulated in
Table 8.
TABLE 8
[_SanipjLocation _____Sod Type f_ Minimum Resistivity (OHM-CM) ____I_pH_1
it E-1@.3' 2 6400 ....7.8
Sample Location Soil Type Amount of Water Soluble Sulfate
In Soil (%-by Weight)
[B-1@3.. I 2 No Detection
9 Chloride Test A chloride test was performed on a representative sample of Soil Type
2 in accordance with the California Test Method (CTM) 422 The test result is presented
in Table 10
TABLE 10
Sample Location Soil Type Amount of Water Soluble Chloride
Lu Soil (% by Weight)
B-1.@ Y 2 I No Detection
I VIV SITE CORROSION ASSESSMENT
A..site. is considered to be cor osi e tO.fOflfldaticm elements, WM18 and drau age Si.. .ctures if one or I more of the following conditions.. exist:
* Sulfate concentration is greater than or, equal to 2000 ppm (02% by weight)
I * Chloride concentration is greater than or equal to 500 ppm (0.05.% by weight)
* pHisles than 55
I For structural elements, the minimum resistivity of soil (or water) indicates the relative quantity of
soluble salts present in the soil (or water) In general, a mimmum resistivity value for soil (or water)
I less than 1.000 ohm-cm indicates the presence of high quantities of soluble salts and a higher
propensity, for corrosion Appropriate corrosion mitigation measures for corrosive conditions should
be selected depending on the service environment, amount of aggressive ion salts (chloride or
I sulfate), pH levels, and the desired service life of the structure
Results of limited laboratory tests performed on selected representative site samples indicated that
I the minurnun resistivity is greater than 1000 ohm-cm, suggesting the presence of low quantities of
soluble salts Test results further indicated that pH levels are greater than 5 5, sulfate concentration JOess than 2000 ppm and chionde concentration levels are less than 500 ppm Based on the results
I ofthe corrosion analyses, the project site is considered non-corrosive The project site is also located
outside of a 1000 feet limit from salt or seawater
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Geotechnical Investigation, Proposed Single-Family Residence March .27, 2017
Sheridan Place, Carlsbad, California (A P N 206-042-47-00) Page 10
Based upon the result of the tested soil sample, the amount of water, soluble sulfate (SO4) was found
to be at "no-detection" levels which is considered negligible according to ACI 318 (SO Exposure
Class with Not.. Applicable severity). Portland cement Type II and concrete with minimum 28 days
compressive strength (fc) of 2500 psi and 0 50 water-cement ratio are typically considered adequate
for.SO Exposure :Cla.ss,. unless otherwise specified or noted..
VI. STOR1 WATER BMPs
.Storniwater BMP facilities, if rcquired.or considered in connectiOn with the project development
should be designed and constructed considering geotechmcal conditions indicated at the site The
implemented management and water treatment control practices shall have no short and long term
impacts on the new bui1dingpad and improvement surfaces, fills and backfllls, underground or
subterranean structures and facilities, and onsite and.. nearby ..Offsi.te improvements
Infiltration testing and detennination of an apparent infiltration rate of site native materials were not
a part of this study at this time However, in general, site subsoil profiles chiefly consist of shallow
topsoils atop dense 1sandstone.T.prrace Deposits, that may generally be.charactethed.as Group B/C hydrologic classification (based on San Diego Hydrology Manual classification) Based on site
available geotechnical data, abioretention/detention system generally consisting of a suitably sized
excavated basin(s) with specially engineered sand filter media and 3A-inch crushed rocks provided
with a perforated pipe(s) at the bottom may be considered appropriate Actual mfiltration testing
I should be used as a basis for providing more detailed and specific recommendations, if appropnate
The bioretent oti/detention: basin(s) should be properly sized for adequate storage capacity with
I filtrations completed not more than 72 hours and vegetation carefully managed to prevent creating
mosquito and other vector habitats.
Periodic.observations, upkeep and continued maintenance of the project stonnwater BMP infiltration
facilities will be required to assure proper functioning and uninterrupted continuous discharge flow
of the captured runoff water. Improper functioning of the proposed infiltration pits or prolonged
pondmg can adversely impact nearby foundation improvements and adjacent properties, or
potentially result in failures In order to avoid such adverse conditions, a well-established
maintenance, program that includes careful management of the infiltration facilities and testing for
proper functioning of the underderarn/outlet pipes should be set in-place and followed by the current
and future home owners In the event poor or under performing conditions develop, as noted during
the scheduled maintenance program, appropriate repairs, maintenance and mitigation should be
immediately carried out as necessary As a minimum, a maintenance schedule consisting of at least
2 times a. year,...before and after the annual rainy season should be considered.
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Geotechmcal InvestLgat1on, Proposed Single-Family Residence March 27, 2017
1 Sheridan Place, Carlsbad, California. (A.P.N. 206-04247-00) Page 11
VIII. CONCLUSIONS
I Based upon the, foregoing investigation, the proposed single-family resider'tial development,, as
currently planned at the project property, is substantially feasible from a geotechnical viewpoint I The project property is generally underlain by sandstone Terrace Deposits at a relatively shallow
depth and is overlain by a section of loose undifferentiated topsoil/disturbed natural ground cover
The following factors are unique to the property and will most impact project construction
I procedures and associated costs.from a, geotechnical.v'ewpoint
1 Evidence of landslides, faults, liquefaction, seismically induced settlements or other adverse
I geologic hazards, which could preclude the planned development was not indicated at project
property The study site is not located near or within the Aiquist-Priolo earthquake fault zone ' established by the State of California Moderate to locally high levels of ground shaking,
however, 'are expected at the site during occasional: periods of seismic activity along distant
active faults.
1 2. The property is generally characterized..by relatively level topography. Significant ground..
modifications are also not anticipated in connection with the proposed pad development
i Final pad surfaces are anticipated to be established at or very near the existing grades
3. Large.natUral or gradedslopes are not present on or near the immediate vicinity ofthe'project
site, nor are any new large graded slopes expected Consequently, slope stability is not
considered a geotechnical factor in the planned development
I4.. A.rdlatively shallow to modest section of loose to very loose topsoil/disturbódnatural ground
deposits, on the order of 2½ feet thick, mantles the project property. Below the upper
topsoil/disturbed natural ground mantle, natural sandstone Terrace Deposits are present I Underlying Terrace Deposits typically occur in weathered loose to medium dense conditions
near the upper exposures becoming dense "to very dense with depth overall. The Terrace
Deposits below the upper weathered zone are competent deposits that can suitably support
the planned new fills, structures and improvement.
5. The site topsoil/disturbed n twaground mantle zand.. the upper weathered section of the
underlying Terrace Deposits are loose deposits not suitable for structural support They
should be stripped (removed) to the underlying dense Terrace Deposits, as approved in the
fie, and placed back asproperly compacted fills in accor4ancewith the recommendations
Of this report.
I 6. Stripping and recompaction remedial grading:workwill be require under all proposed new
constructions and improvements in order to: construct uniform bearing ...d subgrade soil
conditions throughout, as specified in the following sections There should be at least 18
I jhes of well-compacted fills below the. bottom of the deepeSi:: footing(s), :and site
improvements throughout,, unless otherwise approved.
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Geotechnical Investigation, Proposed Srngle-Fainily Residence March 27, 2017
I Shridan Place;.ICaHsbád, California (A.P.N..::20.60424700) . Page '12
7 cut fill, grading creating a daylight transition is no 'expected, and. remedial
I grading efforts will be required over the entire pad surfaces, as specified herein
Consequently, cut-fill transition is not expected to be a factor in the planned site
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development..
8. Project earthwork. operations are: expected to chiefly consist of remedial grading and. foundation bearing and subgrade soils preparation The site topsoil/disturbed natural ground
I mantle is also expected to shrink when recompacted as specified herein, and import soils may
be required to complete grading and achieving final design pad grades..All earthworks,
remedial and fine grading efforts should be completed in accordance with requirements of I the following sections
I 9 Soils generated from the project stripping, removals and over-excavations will generally
consist of sandy deposits that typically work well as site new fills and backfills, provided
they are adequately processed and prepared in accordance with the requirements of this
I report All surface vegetation should be properly cleared and removed from the site as
specified below.
I 10. Based onOur field observations and laboratory testing, final bearing and. subgrade. sOils at the
project property are expected to chiefly consist of sandy to silty sand (SP-SMIS)N) deposits
with very low expansion potential (expansion index less than 20) based on ASTM D-4829
I classification Expansive soils are not considered to be a major geotechrncal factor in the
planned new development.
I i 1 • Natural groundwater. was not encountered in our exploratory test borings to the depths
explored, and is not expected to be a factor in the planned new construction As with all
graded sites, the proper, control of surface drainage and storm water is a critical component
I to overall site and building performance Run off water should not pond upon graded
surfaces, and irrigation water should not be excessive. Over-watering of site vegetation may
also create perched water and the creation of excessively moist areas at finished surfaces and 1 should: be avoided.
Storm water and drainage control facilities, should he designed and installed for proper I control and disposal of surface water as shown on the approved grading or drainage
provement: plans.
I 12 Considering the anticipthd and relatively shallow over-excavations and stripping depths
necessary for the project remedial Igrading efforts, significant construction impacts on the
I . nearby off-site structures and improvements are not anticipated. In. general, added care. will.
berequired to avoid an damages to'the existing nearby on and off site structures, retaining
walls and improvements due to site excavations, remedial earthwork grading and
I cOnstruction. works.
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Gtechnical Investigation Proposed •Single...Fathily Residence March 27,207 I Sheridan Place, Carlsbad, California A.P.N. 206-04247-00).. Page 13
13 Soil collapse and post construction settlements are not expected to be a major geotechnical ' concern provided our remedial grading and foundation recommendations are followed Post
construction settlements are expected to be less than approximately 1 inch and should occur
below the heaviest loaded footing(s) The magnitude of post construction differential
I settlements of site fill deposits, as expressed in terms of angular, distortion, is not anticipated
to:.exceed•..: 4.-inch between similar ad' ac itstrticthral lóments.
I IX. RECOMMENDATION.
The followingrecommendationi. are provided based.on:the.availabI geotechnical data gene. at
I during thisr effort and scheme of the proposed development, as understood Added or modified
recommendations may also be appropriate and should be provided at the time of final plan review
- . phase:
A.. IGradinQ and EárthwOrks
:Significant grade alterations are not anticipated and site .earth work operations are:expected
to mostly consist of relatively minor to modest remedial and fine grading efforts in order to achieve final design grades and construct safe and stable building and improvement surfaces
All site excavations, grading, earthwork, construction, and beanng/subgrade soil preparations
should be completed in accordance with Chapter 18 (Soils and Foundations) and Appendix
"J" (Grading) of the 2016 California Building Code (CBC), City of Carlsbad Ordinances. the Standard Specifications for Public Works Construction, and the requirements of the
following sections wherever applicable.
1. Existing Underground Utilities and..StrUCtureS All existing underground waterlines,.
sewer lines, pipes, storm drains, utilities, tanks, structures, and improvements at or
nearby the project site should be thoroughly potholed, identified and marked prior to the
initiation of the actual site excavations, grading and earthworks Specific geotechmcal
engineering recommendations maybe required based on the actual field locations, invert
elevations, backfill conditions, and proposed grades in the event of a grading conflict
Utility lines may need to be: temporaiily redirected, if necessary, prior to earthwork
I operations and reinstalled upon completion of pad constructions Alternatively,
permanent relocations may be appropriate as shown on the approved plans
I
Abandoned irrigation lines, pipes, and conduits should be properly removed, capped or
sealed off to prevent any potential for future water infiltrations into the foundation
I .bearing and subgrade soils, Voids created by the removals of the abandoned
underground pipes, tanks and structures should be properly backfihled with-co mipacted fills in accordance with the requirements of this report =1
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Geote6nicalIüv.estigafiou,.Propose4 Singie-Farnlly..Residence March27, 2.017 Shendan Place, Carlsbad, California (A P N 206-042-47-00):Page 14
2. Clearing and Grubbing:. Remove all existing surface and subsurface structures, improvements, pipes and conduits, old foundations, asphalt pavings, vegetation, tress,
roots and stumps, and all other unsuitable materials and deleterious matter from all areas
proposed for new fills, improvements, and structures plus a minimum of three horizontal
feet outside the.perimeter, where possible and as approved in the field.
All trash debris and unsuitable materials generated from site demolitions and clearing
efforts should be properly removed and disposed of from the site Trash, vegetation and
construction debris should not be allowed to occur or contaminate new site fills and
backfihls.
The prepared. grounds should be observed, and approved by the project geotechriical
con.ultant or'his.designat&l fi'éldrepresentative"pñor to grading' and earthwork.
3 Stnpping and Removals All existing loose upper surficial topsoil/disturbed natural
ground deposits and upper weathered section of underlying Terrace Deposits in areas of
the planned new fills, structures and improvements plus a minimum of 3 horizontal feet
outside the perimeter, where possible and as directed in the field, should be stripped
(removed) to the underlying dense and competent Terrace Deposits and placed back as
properly compacted fills Actual stripping depths should be established and approved by
the project geotechnical consultant based on field observations and testing of bottom
exposures However, based on the available exploratory test borings, typical stripping
depths are expected to be on the order of 3 feet below the existing grades, or 18 inches
below the bottom of deepest footing(s), whichever is more There should beat least 18
inches of well compacted (minimum 90%) fills below bottom of the deepest footing(s)
throughout, unless otherwise approved. There should also be a. minimum of 18 inches
of compacted fill below rough finish subgrade in the planned parking and improvement
areas, unless otherwise directed in the field
Loally deeper removals may also be necessary based on the actual field exposures :an final grades and should be anticipated..Bottom of all striping and removal exposures
shoUld be additionally ripped, processed and :recompacted to a minimum depth of 6
inches, as a part of initial fill lift placement, as directed in the field The exposed
stripping and removal bottoms should be observed and approved by the project
geotechiiical cOnsuitänt..or. his designated field representative prior to fill placement.
4. Excavation Setbacks and Temporary Slopes: Temporary open excavations and
trenching necessary for the project remedial grading work and construction are expected
to be relatively shallow and at a maximum of 13. feet deep Consequently, significant
construction impacts on the nearby off.site structures and improvements are not
anticipated However, adjacent public and private properties and right-of-ways should
also be properly protected, and permission to excavate and grade near adjacent property
lines and public right-of-ways obtained from the respective owner(s) and public agencies,
as:necessary and appropriate.
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Geotechnical Investigation, Proposed Single-Family Residence March 27, 2017
Sheridan Place, Carlsbad, aiifoniia (A.PN.:206-042-4700) Page 15
.Excãvátibn5 and removals adjacent to the: existing foundations, improvements and
I structures should be performed under observations of the project geotechnical engineer
Undermining existing adjacent foundations, structures, improvements and underground.
utilities to remain should not., be. 'allowed .by the project:' and.. earth- -wo operations.
:emporaly excavations and trenching less:'than the 3 feetmaximlrn maybe devó'loped
I at near vertical gradients, unless otherwise noted or directed in the field However,
performing remedial grading in limited sections (one-half property length maximum)
maybe considered to limit exposures and reduce overall stockpile quantities Temporary
slopes and trench excavations greater than the 3 feet high maximum, if any, may be
constructed at near vertical gradients within the lower 3 1 feet and laid back at 1
I gradients within the upper portions The new fills and backfihls should be properly
keyed-in and benched into the 11 temporary excavation wedge as the fill/backfill
placement progresses.
I More specific recommendations should be given in the field by the project geotechrncal
consultant based on actual .site..exposures. Revised "temporary excavation and trenching
I recommendations including laid back slopes, larger setbacks, completing excavations and
remedial grading in smaller limited sections and the need for temporary shormgftrench
shield supportmay benecessary and should'be anticipated. The project contractor ', shall ' also obtain appropriate permits, as needed, and conform to Cal-OSHA and local
governing, agencies.' 'requirements for ':trenching/Open excavations and safety of the
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workmen., during construction.
- 5 Fill/Backfill Materials, Shrinkage and Import Soils Site stripping, removals, and
excavations will chiefly generate a sandy to silty sandy soil deposits that typically work I well as site new fills and backfihls, provided itis adequately prepared, processed, placed
and compacted in accordance with the requirements of this report Vegetation, roots and
I
stumps, buried pipes and conduits, construction debris, and organic matter, where
encountered, sho ld.beT throughly removed and separated from the fill/backfill mixture
to the satisfaction and approval of the project geotechni.cal consultant.
I ..Onsite. soils may, be .expected. to shrink nearly 10% to 15%, on Vohirne basis,
compacted (minimum. 90%) as specified herein Import soils, if required to complete
I grading and achieve final grades, should be good quality, sandy granular non-corrosive
deposits (SMISW) with very low expansion potential (100% passing 1-inch sieve, more
than 50% passing #4 sieve and less than 18% passing #200 sieve with expansion index
I less than 20) Import soils should be observed, tested as necessary, and approved by the
project geotechnical engineer prior to delivery to thesite. 'Import should also meet
or, exceed engineering characteristic and soil design parameters as specified in the
I folio wing.sections.
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Geotechnical Investigation, Proposed Single-Family Residence March 27, 2017
Sheridan Place, Carlsbad, Caliform'a A.P.N. 206-042-47-00) . Page .16
6 Fill/Backfill Placement, Spreading and Compaction Uniform bearing and subgrade I soil conditions should be constructed throughout the building and improvement surfaces
by remedial and fine grading opeations Site soils should. be adequately processed,.
- thoroughly mixed, moisture conditioned to slightly (20/) above the optimum moisture I levels, or as directed in the field, placed 4h thin (8 inches maximum) uniform horizontal
lifts and mechanically compacted to a minimum of 90% of the corresponding laboratory
I maximum thy density per ASTM D-1557, unless otherwise specified The upper 12
inches of subg'ade soils benëãth the aggregate base layer under asphalt parking areas
Should be coinpacted.t) at least 95% compaction levels.
I 7 Surface Drainage and Erosion Control A critical element to the continued stability
of graded building pads and improvement sites is an adequate stormwater and surface
drainage control.
Surface water should not be allowed to flow toward and pond near the building
I foundations or impact developed building and improvement sites Surface water should
flow away from the building foundations and site improvements in a positive manner
Roof gutters and area drains should.be installed. Over-watering Of the site landscaping
I should also not be allowed Only the amount of water to sustain vegetation should be
provided Site drainage improvements should be shown on the project approved plans
I 8 Engineering Observations; All, remedial grading, bearing and. sübgrade soil
preparations, and earthwork operations including stripping and removals, suitability of
earth deposits used as compacted fills and backfills, and compaction procedures should
I be continuously observed and tested by the project geotechmcal consultant and presented
111:U final as-graded. compaction report. The nature offinished bearing and subgrade
I ,oils..should be confirmed:in the final compaction report..at the completion of grading.
Geotechnical engineering: Obsei:ations: should include 'butnot limited to,the following:
* Initial observation -. After"the site clearing and staking of project limitsi but..hàfore
grading/brushing starts.
I :*. Bottom of stripping (removal) observation - After dense, and competent Terrace, Deposits are exposed and prepared to receive fill or backfill, but before fill or backfill
is placed.
:* Fill/backfill observation - After the fill/backfill: placement'is started but before the
I vertical height of fill/backfill exceeds 2 feet A minimum of one test shall be
required for each 100 lineal feet maximum, in every 2 feet in vertical gain Finish
rough and final pad grade tests. shall be required regardless of fill thickness.
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Geotechnicai Investigation, Proposed :Single.Faniily Residence March 27, 2017
I Sheridan Place, Carlsbad, California (A P N 206-04247-00) Page 17
* Foundation trench and subgrade soils observation - After, the foundation trench
I excavations and prior to the placement of steel reinforcing for proper moisture and
specified compaction levels There should be at least 18 inches of compacted fills
below bottom of the deepest footing(s) throughout, unless otherwise approved
I There should also be a minimum of 18 inches of compacted fill below rough finish
subgrade in the planned parking and improvement areas.
I * Geotechnical foundation/slab steel observation - After the steel placement is
completed hUtbëfore the sob eduled concrete. pour.
I * Underground utility/plumbing trench observation - After the trench ...excavations but
before placement of pipe bedding or installation of the underground facilities Local
and Cal-OSHA safety requirements for open excavations applyw Observations and
I testing of pipe bedding may also be required. by the project geoteciiriical enghieer.
* Underground utility/plumbing trench baókfill observation - After the back.fill. I placement is started above the pipe zone but before the vertical height of backfill
exceeds 2 feet Testing of the backfill within the pipe zone may also be required by
I the governing agencies Pipe bedding and backfill materials shall conform to the
governing agencies' requirements and project soils report if.applicable.. All. trench
backfihls should be mechanically compacted to a minimum of 90% compactIon levels
I unless otherwise specified. Plumbing frenches.more than 12 inches deep maximum
under the floor slabs should also be mechanically compacted and tested for a
minimum of 90% compaction levels Flooding or jetting techniques as a means of
compatiOn method shouldI.not be allowed.
* Ittiprovernent subgrade observation - Prior to the placement of concrete for proper,
I rnoisture.and specified compaction levels.
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B. Footings. and Slab-On-Grade Foundations
The following recommendatiohs are. consistent with the anti cipated.sandy to silty, sand.. (SP-SM/SW) bearing soils with veiy expansion potential (expansion index less than 20), and site
I indicated geotechnical conditions All,design recommendations should be further confirmed
and/or -revised as necessary at the final plan review phase, and at..: completion of remedial.
I grading works based on actual testing of.fináibesring and subgrade soils:
1 Conventional shallow stiff concrete footings and slab-on-grade floor type foundations
I ,maybe considered for support of the new restaurant building extension All foundations
should be supported on well-compacted fills, placed in accordance with the requirements
of this report There should beat least 18 inches of compacted fills below the bottom of
the.deepest footing(s) throughout, unless otherwise approved.
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Geotechnical Investigation, Proposed Smgle-Family Residence March 27, 2017
I Place, Carlsbad, California .A.P.N. 2064424.7-00) Pag..18.
2 Perimeter and interior, continuous strip footings should be sized at least 15 inches wide
I and 18 inches deep for single and two story buildings Spread pad footings, if any,
should be at least 30 inches square and 12 inches deep Footing depths are measured
from the lowest adjacent ground surface, not including the sand/gravel layer underneath
I the floor slab. Exterior continuous footings% should enclose the entire huildingperimeter
Penneter continuous and interior strip foundations should be reinforced by at least:.four
I #4 reinforcing bars. Piaceaminimuin oftwo #4 bars 3 inches above the bottQrn.of the footing and a minimum of two #4 bars 3 inches below the top Reinforcement details for
spread.padfOotings should be provided by the project architect/structural engineer
.31 Interior slabs should bea minim.urn. of 4% inches iti thickness reinforced with minimum
#3 reinforcing bars spaced 18 inches on center maximum each way placed mid-height
in the slab Provide re-entrant corner reinforcement for all interior slabs based on slab
geometry and/or interior column locations, as generally depicted on the enclosed Figure
8 Slabs should be underlain by 4 inches of clean sand (SE 30 or greater) which is
provided with a well-performing moisture barrier/vapor retardant (minii ii mum I 0-mu
Stego) placed mid.height.in:.the sand. Alternatively, a 4-inch thick base of compacted
'/2-lnth clean aggregate provided with the vapor barrier (minimum 15-mil Stego) indirect
contact with (beneath) the concrete may also be considered provided a concrete mix that
can address bleeding,. ..shflnkageand curling is used.
Provide "softcut" contraction/control joints consisting of sawçuts. spaced 1.0 feet on
centers each. way for the. all-interior slabs. Cut as soon as the slab will support the weight
of the saw and operate without disturbing the final finish which is normally within 2
hours after final finish at each control joint location or 150 psi.to 800 psi The saw, cuts
should be minimum l-inch in depth but should not exceed 11A-mches deep maximum
Anti-ravel skid plates should be used and replaced with each blade to avoid spalling and
raveling. Avoid wheeled equipments.across cuts for at least 24 hours.
4 Foundation trenches and slab subgrade soils should be observed and tested for exposing
suitable bearing strata, proper moisture and specified compaction levels and approved
by the project ge.technical. consultant prior to the placement Of:concrete.
C. Soil Design Parameters
The followingsoil:design parameters are based upon tested representative samples of on-site
earth deposits All parameters should be re-evaluated when the characteristics of the final
as-gradedsoils have been specifically determined:
Design:.soil unit weight = 129 pd
Design, angle ofinternal friction ofsoil 34. degrees.
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GèOtechnieal investigation, Proposed Singe-FanIiJy Residence March 27, 2017
Sheridan Place, ...Carlsbad, California . A.P.N. 206-042-47-00) Page 19
I. Design active soil preasure for retaining structures 36 pef, (EFP),;, level backfll,
cantilever,: unrestrained walls..
4 Design at-rest soil pressure for retaining structures 57 pcf (EFP), non-yielding,
restrained .wails,
S. Design passive soil resistance for retaining structures I pf.(EFP), level surface., at
the toe.
6 Design coefficient of friction for concrete on soils = 0.4 1
7. Net allowable foundation pressure (minimum 15 inches'wideby l:8:inches deep footings)
= 2000 psf..
8.. Allowable. lateral. beating pressure. (all structures except: :retaining 'walls) = 200'ps'ft.
Notes:
'U. * Use a minimum safety factor of,L 5 for wall over-turning and slidmg stability However,
because large movements.,must, take "plac'e befOre maximum passive resistance can' be.
developed, a minimum safety factor of 2 may be considered for sliding stability
particularly where sensitive structures and improvements are planned near or on top of
retaining walls.
* When combining passivepressure and frictional resistance the passive component should
be reduced by one-third.
* The indicated net allowable foundation pressure provided herein was determined based
on a minimum 15 inches wide by 18 inches deep footings and may be increased by 20%
for each additional foot of depth and 20% for each additional foot of width to a
maximum of 5500 psf The allowable foundation pressures provided also apply to dead
plus live loads and may be increased by one-third for wind and seismic loading
* The lateral..bearing earth pressures maybe increased by the amount.of designated value
for each: additional foot of depth to a maximum 1500 pounds persquare:foot.
D. Exterior Concrete Slabs and Flatworks
1. All exterior slabs (walkways, patios) supported on potentially very low expansive
subgrade soils should be a minimum of 4 inches in thickness, reinforced with minimum
6X6-IOX10 welded wire mesh (or #3 bars at 18 inches on center, both ways) laced near
the slab mid-height. The: subgrade soils should be compacted tol minimum 900/0 compaction levels at the time of fine grading and before placing the slab reinforcement
Reinforcements lying on subgrade'v ill be ineffective and shortly corrode due to lack of
adequate concrete cover..Reinforcing bars should be correctly placed extending through
the construction joints tying the slab panels In construction practices where the
- Residence, March 27, 2017
Sheridan Place Carlsbad, .CáIiforniaA.P.N.206-O42-47-0O). Page:20
reinforcements are discontinued or cut at the construction joints, slab panels: should.. be tied together with minimum 18 inches long #3 dowels at 18 in on centers placed
mid-height in the slab (9. inches on either side of the joint).
.2. Provide "tool joint" or ' oftcut"ccntraction/eontroljoints spaced 10 feet On center.(not
to exceed 12 feet maximum) each way. The larger dimension of any panel shall not
exceed 125% of the smaller dimension Tool or cut as soon as slab will support weight,
and can be operated without disturbing the final finish, which is normally within .2 hours
after final finish at each control joint location or. 150 psi to 800 psi Tool or softcuts
should be a minimum...of 1 -inch, but should not exceed 1 lAincb:4eep maximum. In case
of softcut joints, anti-ravel skid plates should be used and replaced with each blade to
avoid spallingand raveling Avoid wheeled equipments:across cuts for at.ieast 241 hours.
Joints shall intersect free-edges at a 900 angle and shall extend straight for a minimum
of 11/2 feet from the edge The minimum angle between any two lntersectmg joints shall
be 80° Align joints of adjacent panels Also, align joints in attached curbs with joints
in slab panels Provide adequate curing using approved methods (curing compound maximum coverage rate 200 .sq ft./gaL)...
All -exterior slab designs should be.confirnied.in the final as-graded compaction report.
Subgráde sOils should be tested for, proper moisture andsp.ecified compaction levels and
approved by the: project geotechnical consul tant.prior to the placement. of concrete
E. Propostd:SRa
A, spa is planned iti the southwest corner of the project property, as depicted on the: enclosed
Figure 2. Competent natural sandstone TerraceDeposits are expected to occur:.at a relatively
shallow depth, approximately .3 feet below the existing ground surfaces, and may be anticipated to be exposed throughout the spa excavations.,Spa excavation should be
observed to confirm uniform undisturbed natural sandstone Terrace Deposits throughout, and
approved by the project geotechiucal engineer. However, minor remedial grading efforts and
,preparation of. bottom of spa excavation may become required based on actual field. conditions and possible cut-fill daylight exposures, as evaluated in the field, and should be
anticipated In case of cut-fill daylight exposures, the cut portion of the spa bottom exposure
should be undercut a minimum of 12 inches and reconstructed to finish elevation with
minimum 90% compacted fills for providing a uniform compacted subgrade soil condition
throughout.
The spa shou14 be design.d. and constructed by the project.design/build contractor based on
the soil design parameters.provided in this report The spa may be designed for very low
expansive soil conditions:(expansion index less than.20). The spã.structure should also be
provided with a minimum 15 inches wide by 18 inches deep grade beam remforced with
minimum 244 bars top and. bottom around the top of concrete shell.
nf'hniri Tivevt *irni Prnnng ,d .Sinu1iThn
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Geotechiucal Investigation, Proposed Single-Family Residence March 27, 2017
I Sheridan Place, Carlsbad, California (A P N 206-042-47-00) Page 21
I
K: Pavement Desigi
Remedial subgrade preparation consisting of removal (stn rn ppg) and recompaction of upper
loose soils to the underlaying dense Terrace Deposits, or 18 in minimum, will be
1 required under all site paving surfaces unless otherwise approved or directed in the fills All
pavement remedial grading works should be completed in accordance with the requirements
of this report, and observed, tested and approved by the project geotechnical consultant prior
I to the construction Of actual :phh1eh1t section,
I I Asphalt Paving Specific pavement designs can be best provided at the completion of
rough grading based on R-value tests of the actual finish subgrade soils, however, the
following structural sections may be considered for initial planning phase and cost
I estimating purp ses only (not for construction);
* A minimum section of 4 inches asphalt concrete (AC) on 6 inches Caltrans Class 2 ' aggregate base (AB) or theminimurn. structural .section..required by City of Carl sbad,
whichever is more, may be considered for the onsite asphalt paving surfaces outside
the private and public right-of-way Actual designs will depend on final subgrade R-
I value and design TI, and the approval of the Cityof Carlsbad.
* The asDhalt. concrete layer (4-inch total :SCtI0fl) may consist of 2.5 inches of a
I bind a:eour e.(4-inch aggregate) and l.5::inchcs offinishtop course (½ or
inch aggregate as approved by the city) topcoat, placed in accordance with the
applicable local and regional codes and standards Class 2 aggregate base (AB) shall
I móet or exceed the requirements. set forth in the most current California Standard
Specification (Caltrans Section 26-1 02A)
I * Aggregate: basematerials (AB) should be compacted to a minimum 95% of the
corresponding maximum dry density (ASTM D-1 557). Subgrade soils beneath the
I asphalt paving surfaces should also be compacted. to a minimum 95% of the
corresponding maximum dry density within the upp.çr. 12 inches.
I .2. FCC Pavings: ResidentialPCC.driveways and .parking:supported on very low expansive
(expansion.index.lessthan.20) granular subgrade soils should be .1a minimum of 5 inches
in thickness, reinforced with #3 reinforcing bars at 16 inches on centers each way placed
at mid-hi ightinithe slab, ..Subgrade soil beneath thePCC driveways and parking should
be compacted to a minimum 90% of the corresponding maximum dry density, unless
otherwise specified.
Reinforcing bars should be correctly placed extending through the. construction (cold).
joints tying the slab panels In construction practices where the reinforcements are
n J discontinued or cut at the constructiooints, slab panels should be tied together with
mimmuin 18 inch long (9 inches on either side of the joint) #3 dowels (dowel baskets)
at 16 inches on centerslplaced .mid..:hei.ghtin the slab.
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1 Sheridan Place, Carlsbad, California (A.P.N. 206-042-47-00)
- Page 22
Provide "tool joint" or "soficut" contraction/control joints spaced 10 feet on center (not ' to exceed 15 feet maximum) each way. The larger dimension of any panel shall not
exceed 125% of the smaller dimension. Tool or cut as soon as the slab will support the
weight and can be operated without disturbing the final finish which is normally within
1 2 hours after final finish at each control joint location or 150 psi to 800 psi. Tool or
soficuts should be a minimum of 1-inch in depth but should not exceed 1 'A-inches deep
maximum. In ease of soficut joints, anti-ravel skid plates should be used and replaced
I with each blade to avoid spalling and raveling. Avoid wheeled equipments across cuts
for at least 24 hours.
I Joints shall intersect free-edges at a 90° angle and shall extend straight for a minimum
of 1 Y2 feet from.. the edge. The minimum angle between any two intersecting joints shall
I
be 80°. Align joints of adjacent panels. Also, align joints in attached curbs with joints
in slab panels. Provide adequate curing using approved methods (curing compound
maximum coverage rate = 200 sq. ftigal.).
1 3. Permeable. Interlocking Concrete Payers PICP: Permeable Interlocking Concrete
Payers (PICP), if considered as apart of the project stonnwater quality treatment BMPs
I should consist of a self-contained system disallowing saturation of adjacent foundation
bearing soils, wall backfihls and site improvement subgrade In general, PICP pavements
should maintain a minimum clear distance of 3 feet. TO the building foundations with
I finish subade sloped away at a minimum 2% onto a i2.hiches wide collector trench.
along the low edge provided with a 4-inch diameter (Sch 40 or SDR 35) underdrain pipe
surrounded with %-inch crushed rocks, as conceptually.shown in the enclosed Typical
I Permeable Paver Detail, Figure 9. In case of nearby fill embankments and wall backfills.,
a minimum 10.feet.clear setback should be considered, unless otherwise approved. The
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perforated underdrain pipe should discharge collected water into an appropriate 'storm drainage facility Perimeter curb edge restraints should be provided, and bottom and sides
of the system lined with an impervious liner, as shown, unless otherwise approved.
I The impervious liner on the bottom and sides of the PICP system may be eliminated and
the paving constructed with 12 Inches clear distance from the building foundations
I provided a minimum 8 inches wide concrete slurry cut-off wall (deepened edge restraint)
is constructed extending a minimum of 24 inches below the bottom of the adjacent
perimeter foundations. The cut-off wall (deepened e.ge restraint) should be constructed
I prior to building foundation trenching. Nearby site structures and improvements should
also be protected with similar cut-off walls (deepened edge restraints) as needed
I . PICP pavement structural sectionihould consist of 31A-mob, PICP over a minimum Of
2 inches ofASTM No 8 bedding course/choke stone over a minimum 8 inches ofASTM
No.. 57 stone base course over a minimumof 12 inches of 95% compacted subgrade (per
ASTM D-1 557), unless otherwise approved. Bedding course/choke stone and base
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Geotechnical investigation, Proposed Single-Fan. y Residence. 'March 27, 20.17
Sheridan Place, Carlsbad, California (A.P.N..
. Páge'23
course stone should also.,be Well compacted, consolidated and interlocked (avoid
crushing the underdrain pipes) with heavy construction equipments. ASTM No. 8, No.
9• or. No. 89 should bee, used for joint materials 1 depending on the joint size and per
manufacturer recommendations.
Gradation requirements for ASTM No 57, No 8, No 89 and No 9 are as follows
TABLE 11
Sieve
Size
Percent Passing
No. 57 No.8 No. 89 No.9
1W 1{)O
1" 95.to.1O0
25 to .60 100 100
85 to 100 90t6 100 100
No;4 646 10: 10to30 20...to.55 85.:tol.O0
No. g: 0 010 5 to 30 10 to 40
No. .16 0 to 5 0 to. 10 010 10.
No. 50 0 to 5
4. GeneralPaving: Base scction:and subgrade preparations per structural section d.sign.
will be required for all surfaces subject to traffic including roadways, traveiways, drive
lanes, driveway approaches and ribbon (cross) gutters Driveway approaches within the
public right-of-way should have 12 inches subgrade compacted to a minimum of 95%
compaction levels and provided with a 95% compacted Class '2 base section per the structural section design.
Base layer- under cub and gutters should be compacted to a minimum of 95%, while.
subgnide soils undercurb and gutters, andbase and subgzade under sidewalks should.be
compacted to a minimum of 90% compaction levels, unless otherwise specified Base
section may not be required under curb and gutters and sidewalks, in the case of very low
to non-expansive. .subgrade soils (expansion index less than 20). More speôific
recommendations should be given in thefinal as-graded compaction report.
G. General Recommendations
1. The. minimum foundation design and steel reinforcen lent1 provided herein are based on I soil characteristics and are not intended to be in. lieu of reinforcement necessary for
structural consideration.
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2.. Adequate: staking and grad .ng .contt.l..is .a ciitiC5i factor in properly completing the:
recommended remedial and site grading operations Grading control and staking should
be provided by the project grading contractor or surveyor/civil engineer, and is beyond
the geotechnical engineering services Staking should apply the required setbacks shown
on the approved plans, and should conform to setback requirements established by the
governing agencies and applicable codes for off-site private and public properties and
property lines, utility easements, right-of-ways, nearby structures and improvements,
leach fields and septic systems, and graded embankments. Inadequate staking and/or lack
of grading control may result in illegal encroachments or unnecessary additional grading
that Will increase construction costs.
3. Open Or:backfilled trenches parallel with a footing shall not be below a projected plane
having a downward slope of 1-unit vertical to 2 units horizontal (50%) from a line 9
inches above the bottom edge of the footing, and not closer than 18 inches from the face
of such I footing.
44 Where pipes cross under-footings, the footings shall be specially designed Pipe sleeves
shall be provided where pipes cross through footings or footing walls, and sleeve
clearances shall provide for possible footing settlement, but not less than I-inch all
around the pipe.
All underground utility, and plumbing trenches should he mechanicallycothpacted .
minimum of 90% of the maximum dry density of the soil unless otherwise specified
Care should be taken not to crush the utilities or pipes during thecompaction of the soil.
Non-expansive, granular backfill soils should be used Trench backfill materials and
compaction levels beneath pavements within the:ptiblicright-of-waysb1.conform.tothe. requirements of governing agencies..
. Large retaining walls are not anticipated. In general, expansive c1ayeysoils should nOt
be used for backfihlmg of any retaining structure All retaining walls should be provided
with a 1:1 wedge of granular, cOmpacted backfill measured: from the base of the wall
footing to the finished surface and a well-constructed back drainage system as shown on
the enclosed Figure 10 Planting large trees behind site building retaining walls should
be .avoided.
Site drainage over.the finished pad surfaces should flow away-from structures on the
street in apositivemanner Care hould betaken during the construction, improvements,
and fine grading phases not 164i I srupt the designed drainage patterns Roof lines of the
buildings should be provided with of gutters Roof water should be collected and
directed away from the buildings and structures to a suitable location
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Geotechnical Investigation, Proposed Single-Family Residence March 27, 2017 Sheridan Place, Carlsbad, California (A.P.N. 206-042-47-00) Page 25
Final plans should reflect preliminary recommendations given in this report. Final
I . foundations and grading plans may also be reviewed by the project geotechnical
consultant for conformance with the requirements ofthe geotechnical investigation report
outlined herein. More specific recommendations may be necessary and should be given
I when final grading and architectural/structural drawings are available.
All foundation trenches should be observed to ensure adequate footing embedment and I ... . confirm competent bearing soils. Foundation and slab reinforcements should also be
observed and approved by the project geotechnical consultant.
I 10. The amount of shrinkage and related cracksthat occurs in the concrete slab-on-grades,
fiatworks and driveways depend on many, factors, the most important of which is the
I . amount of water in the concrete mix. The purpose of the slab reinforcement is to keep
normal concrete shrinkage cracks closed tightly.; The amount of concrete shrinkage can
be minimized by reducing the amount of water in the mix. To keep shrinkage to a
minimum the following should be considered:
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Use the stiffest mix that can be handled and consolidated satisfactorily.
' Use the largest maximum size of aggregate that is practical. For example, concrete
made with %-inch maximum size aggregate usually requires about 40-lbs. more
I (nearly. 5-gal.) water per cubic yard than concrete. with 14nch aggregate
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* Cure the concrete as long as practical.
The amount of slab reinforcement provided for conventional slab-on-grade
construction.. considers that good quality concrete materials, proportioning, I craftsmanship, and control tests where appropnate and applicable are provided..
I .13. A preconstruction meeting between representatives of this office, the property owner or
planner, city inspector as well as the grading contractor/builder is recommended in order
to discuss grading and construction details associated with.site development.
I X. GEOTECHNICAL ENGINEER OF RECORD (GER)
I Geotecimleal Solutions, Inc..is the geotechnical engineer of record (GER) for providinga;
specific scope of work or professional serviceunder a contractual agreement uni ess it is terinated.
or canceled by either the client or our firm. In the event a new geotechnical consultant or soils
I engineering firm is hired to provide added engineering services, professional consultations,
engineering observations and compaction testing, AWGeotechnicalSolations, Inc. will no..longer
be the geotechnical engineer of the record,. Project transfer should be conipleted.in accordance with the California Geoteclinical Engineering Association (CGEA) Recommended Practice for Transfer
of Jobs Between Consultants.
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Geotecbiucal Investigation, Proposed Single-Family Residence March 27, 2017
I Sheridan Place, Carlsbad, California (A P N 206-042-47-00) Page 26
Then geotechnical consultant or soils engineering firm should review all previous geotechnical ' documents, conduct an independent study, and provide appropriate confirmations, revisions or,
design modifications to his own satisfaction The new geotechnical consultant or soils engineering
firm should also notify in writing SWGeotechuical Solutions, Inc. aid submit proper notification
I to the City of Carlsbad for the assumption of responsibility in accordance with the applicable codes
and.standards (1997 UBC Section: 3317:8).
I LIMITATIONS:
I The c. .nclusions and recommendations provided herein have been based On available..data obtained from the review of pertinent reports and plans, subsurface exploratory excavations as well as our
experience with the soils and formational materials located in the general area. The materials
I encountered on the project site and utilized in our laboratory testing are believed representative of
the. total area; however, earth materials may, vary in characteristics between excavations.
Of necessity, We in sume.a,certain degree of continuity between exploratory excavations and/or natural exposures It is necessary, therefore, that all observations, conclusions, and recommendations
be verified during the grading operation In the event discrepancies are noted, we should be
contacted immediately so that an observation can be made and additional recommendations issued
if required.
The recommendations made -in this report are applicable to the site :at. the time this report was.
prepared It is the responsibility of the owner/developer to ensure that these recommendations are
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canied Out .inthe field.
It is almost impossible to predict with certaintythe future performance of a property. The future
behavior of the site is also dependent on numerous unpredictable variables, such as earthquakes,
I rainfall, and On-site, drainage patterns..
I The firm of SRIN Geotechnical Solutions, Inc , shall not be held responsible for changes to the physical conditions of the property such as addition of,fill soils Pr changing drainage. patterns which
occur without our observation or control.
I This report should be considered valid for a period of one year and is subject to review by our firm
following that time If significant modifications are made to your tentative construction plan,
I especially with respect to finish pad elevations, and height and gradients of graded slopes, this report
must be. presented to us for review,: and possible revision,
I .This "report is.issued'with the un.dci standing that the owner or his representative is responsible for
ensuring that the information and recommendations are provided to the project architect/structural
engineer so that they can be incorporated into the plans Necessary steps shall be taken to ensure that
I the project general contractor, and:.subcontractors carry out such recommendations during
construction .
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Mark Burwell
CEG #2109
Distribution: Addressee (3, e-mail)
Geotechnical Investigation, Proposed Single-Family Residence March 27, 2017. Sheridan Place, Carlsbad, California (A P N 206-042-47-00) Page 27
The project geotechnical engineer should be provided the opportunity for a general review of the
I project final design plans and specifications in order to ensure that the recommendations provided
in this report are properly interpreted and implemented If the project geotechnical engineer is not
provided the opportunity of making these reviews, he can assume no responsibility for
I misinterpretation of his recommendations.
SMS Geotechiücal Solutions, Inc., warrants that this has been prepared within the limits I prescribed by our client with the usual thoroughness and competence of the engineering profession
No other warranty or representation, either expressed or implied, is included or intended.
I Once again, should any questions arise concerning this report, please do not hesitate to contact this office. Reference to our Project NO. GI-17-02-107 will help to expedite out response to your inquiries.
We appreciate this opportunity to be óf service .to you.
I SMSGeotechnical Solutions,. Inc.
S1S GEOTECHNICAL SOLUTIONS. INC.
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