HomeMy WebLinkAboutCDP 2019-0015; SAUER RESIDENCE; LIMITED GEOTECHNICAL INVESTIGATION - PROPOSED NEW BUILDING ADDITIONS AND REAR YARD SITE IMPROVEMENTS, 2465 JEFFERSON STREET, CARLSBAD, CALIFORNIA; 2017-10-02LIMITED GEOTECHNICAL INVESTIGATION
PROPOSED NEW BUILDING ADDITIONS
AND REAR YARD SITE IMPROVEMENTS
2465 JEFFERSON STREET
CARLSBAD, CALIFORNIA
October 2, 2017
Prepared For:
Carefree Holdings, LLC
Mr. Chris Sauer
2465 Jefferson Street
Carlsbad, California 92008
Prepared By:
SM§ Geotechnical Solutions, Inc.
5931 Sea Lion Place, Suite 109
Carlsbad, California 92010
Project No. GI-17-09-139
TABLE OF CONTENTS
PAGE
I. INTRODUCTION ...................................................... 1
II. SITE DESCRIPTION ......................................•............ 1
III. PROPOSED BUILDING ADDITIONS AND IMPROVEMENTS ............... 2
IV. SITE INVESTIGATION ................................................. 3
V. GEOLOGIC CONDITIONS .............................................. 3
A. Earth Materials ..................................................... 4
B. Groundwater and Surface Drainage .................................... 4
C. Slope Stability ....................................................... 4
D. Faults/Seismicity .................................................... 5
E. Seismic Ground Motion Values ........................................ 7
F. Geologic Hazards .................................................... 7
G. Laboratory Tests and Test Results ...................................... 7
VI. SITE CORROSION ASSESSMENT ...................................... 11
VII. CONCLUSIONS ...................................................... 11
VIII. RECOMMENDATIONS ................................................ 14
A. Remedial Grading and Earthworks .................................... 14
B. Footings and Slab-on-Grade Foundations ............................... 19
C. Underpinning Grade Beam ........................................... 21
D. Soil Design Parameters .............................................. 21
E. Swimming Pool Construction ......................................... 23
F. Exterior Concrete Slabs, Pool Decking, Patios and Flatwork ............... 25
G. General Recommendations ........................................... 26
IX. GEOTECHNICAL ENGINEER OF RECORD (GER) ....................... 28
X. LIMITATIONS .........................•............•....•........... 28
FIGURES
Regional Index Map ........................................................... 1
Geotechnical Map ............................................................ 2
Test Pit and Boring Logs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 -6
Geologic Cross-Section ........................................................ 7
Fault-Epicenter Map .......................................................... 8
Sieve Analysis ................................................................ 9
Typical Isolation Joints and Re-Entrant Corner Reinforcement ..................... 10
Typical Grade Beam Detail for Underpinning Wall Footings ......................•. 11
Typical Swimming Pool Construction Concept ................................... 12
Typical Retaining Wall Back Drainage .......................................... 13
APPENDIX
Project No. GI-17-09-139
October 2, 2017
Carefree Holdings, LLC
Mr. Chris Sauer
2465 Jefferson Street
Carlsbad, California 92008
§.ff§ GEOTECHNICAL SOLUTIONS, INC.
Consulting Geotechnical Engineers & Geologists
5931 Sea Lion Place, Suite 109
Carlsbad, California 92010
760-602-7815
smsgeosol.inc@gmail.com
LIMITED GEOTECHNICALINVESTIGATION, PROPOSED NEW BUILDING ADDITIONS AND
REAR SITE IMPROVEMENTS, 2465 JEFFERSON STREET, CARLSBAD, CALIFORNIA
Pursuant to your request, 6.MS Geotechnical Solutions Inc. has completed the attached Limited
Geotechnical Investigation report for the proposed new building additions and rear yard site
improvements at the above-referenced property.
The following report summarizes the results of our subsurface exploratory boring and test pit
excavations, field in-situ testing and sampling, laboratory testing, engineering analysis and provides
conclusions and recommendations for the proposed new building addition and site improvements,
as understood. From a geotechnical engineering standpoint, it is our opinion that construction of the
planned new building additions and site improvements substantially as proposed, 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 construction plans and allow
more accurate estimates of associated costs.
If you have any questions or need clarification, please do not hesitate to contact this office.
Reference to our Project No. GI-17-09-139 will help to expedite our response to your inquiries.
We appreciate this opportunity to be of service to you.
LIMITED GEOTECHNICAL INVESTIGATION
PROPOSED NEW BUILDING ADDITIONS AND REAR SITE IMPROVEMENTS
2465 JEFFERSON STREET
CARLSBAD, CALIFORNIA
I. INTRODUCTION
The property investigated herein consists of an existing single-family residential development
located at the referenced address within the limits of the City of Carlsbad. The project location is
shown on a Regional Index Map attached to this report as Figure 1. The approximate study site
coordinates are 33.1697°N latitude and -l 17.3488°W longitude.
We understand that the existing building will be expanded with first and second floor additions, and
the rear yard will receive new improvements, including a swimming pool. Consequently, the
purpose of this investigation was to evaluate geotechnical conditions at the new building addition
and site improvement locations to evaluate their influence upon the planned new construction.
Exploratory borehole drilling and a test pit excavation, in-situ testing and soil sampling, laboratory
testing, and engineering analysis were among the activities conducted in conjunction with this effort
which has resulted in the geotechnical planning and foundation recommendations presented herein.
The scope of this report is limited to those areas planned for new building additions and site
improvements as specifically delineated in this report. Other areas of the property and existing
structures/improvements, not investigated, are beyond the scope of this report.
II. SITE DESCRIPTION
A Geotechnical Map, reproduced from the project String Line Exhibit (Sheet A 1 ), showing existing
site conditions and the proposed new building additions/rear yard improvements at the study
property, is attached herein as Figure 2.
In general, the project property is located in a coastal residential neighborhood, within the City of
Carlsbad, on the eastern flank of a hillside along the Buena Vista Lagoon. Jefferson Street bounds
the property along the eastern margin, while existing neighboring residential developments occur
north and south. The existing nearly level building pad at the property is currently occupied by an
older single-family building with associated structures and improvements. The level pad surfaces
in the rear yard are marked with a minor graded slope which gives way to nearly flat areas that
terminate at an existing retaining wall. The retaining wall marks the top of the western perimeter
descending slope. The descending hillside is a large graded slope with drainage terraces, which
descends nearly 40 feet at 2: 1 (to locally steeper) gradients to natural hillside terrain and the Buena
Vista Lagoon embankment below. Rear slope areas are heavily overgrown with trees and shrubs.
Evidence of slope instability is not readily apparent. Current site drainage is considered poor to
marginal overall. Surface drainage at the eastern portions of the property appears to locally pond in
front yard areas or flow toward Jefferson Street, while western rear yard drainage appears to flow
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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toward the retaining wall along the top of descending slope. Excessive scouring or erosion is not
in evidence.
The original residence at the property was apparently constructed more than 25 years ago.
Subsequent additions and modifications were supposedly carried out since the original development.
Engineering, construction, inspection, and testing records pertaining to the original site development
and subsequent building additions and modifications are not available for our review. However, our
project document search located a copy of a more recent geotechnical report for the neighboring
property (2435/2433 Jefferson Street):
Updated Preliminary Geotechnical Evaluation
APN 155-140-41
Carlsbad, San Diego County, California
Prepared by Geosoils, Inc.
W.O. 5763-A-SC, dated October 15, 2008
The referenced report is on file with our firm and a copy can be obtained upon request.
III. PROPOSED BUILDING ADDITIONS AND IMPROVEMENTS
Proposed building additions and rear yard site improvements are depicted on enclosed Geotechnical
Map Figure 2. As shown, the main building is planned for first floor expansion and second floor
additions. First floor building expansion will include a new attached 2-car tandem garage on the
southeast comer, a music room/ bedroom 2 on the southwest comer, and a dining room pop-out at
the northwest comer. Second floor additions will include a home gym above the existing garage on
the northeast corner, a home theater above the new garage on the southeast corner, an office with a
terrace, bedroom/bathroom 3, and associated building modifications.
The back yard improvements will include a new pool with a disappearing edge and a spa on the
western pad margin, east of the existing retaining wall that marks the top of the rear descending
slope. Associated improvements will include pool decking, patio, stairs, and landscaping features.
The project property is subject to string-line setback requirements, as shown on the pertinent plans,
and although the string-line may be located on the west of the existing retaining wall, the City
Hillside Development Ordinance does not permit development on the perimeter downhill slopes.
Consequently, the new pool, deck, and patio should be located east of the existing retaining wall.
Based on current plans, the existing retaining wall will mostly remain in-place, except where
removed and replaced as a part of the new pool construction, subject to approval by the City of
Carlsbad. In addition, the City of Carlsbad also requires a building setback from the top of slope.
The setback is an imaginary line measured at 0.7:1 gradients (horizontal to vertical) from the top of
slope. The indicated imaginary building setback line is shown on Figure 2.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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Significant cut-fill grading and ground modifications are not anticipated with the new building
additions and pool final grades established at or near existing grades. Earthwork operations are
. expected to mostly consist of minor to modest remedial bearing and subgrade soil preparation
efforts, pool excavations approaching 4 feet deep maximum, and minor filling for achieving rear
patio grades.
Detailed foundation and building plans are also not yet available. However, the use of a
conventional wood-frame with exterior stucco type construction supported on shallow continuous
strip and spread pad footings, and/or grade beam type foundations with slab-on-grade floors is
anticipated. In order to minimize ground disturbance, facilitate construction near the top of rear
descending slope, and reduce remedial grading earthwork quantities, the new swimming pool and
spa are recommended for support on a structural concrete platform which spans over cast-in-place
(CIP) drilled caissons.
IV. SITE INVESTIGATION
Subsurface conditions at the property were substantially determined by the excavation of three
exploratory test borings drilled with a limited access tri-pod mounted rotary beaver drill rig, and one
hand-dug test pit near the eastern building perimeter foundation. The purpose of our exploratory test
pit excavation was to evaluate the immediate foundation bearing soils and locally expose existing
building foundations to measure footing depth and width. Based on our limited exposures, the
existing foundation was measured approximately 9 inches deep below the adjacent ground surface
(BGS) and roughly 12 inches wide.
Test pit and boring excavations were logged by our project geologist, who also directed in-situ
testing and retained representative subsoil samples at frequent intervals for subsequent laboratory
testing. Test pit and boring locations are shown on the attached Figure 2. Logs of the test pit and
borings are enclosed with this report as Figures 3 through 6. The subsurface profile based on the
exploratory test excavations is illustrated in the enclosed Geologic Cross-Section, Figure 7.
Laboratory test results and engineering properties of selected soil samples are summarized in a
following section.
V. GEOTECHNICAL CONDITIONS
The study property is mostly characterized by a nearly level graded building surface which
terminates along the western perimeter with a relatively large descending graded slope. The existing
building pad was likely originally created by minor remedial grading efforts along with minor filling
in the western reaches of the property. Grading records for the development of the existing pad were
not available for our review
The following geotechnical conditions are apparent at the site:
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
A. Earth Materials
October 2, 2017
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Terrace Deposits (Qt) -The study locations are underlain at shallow depths by Pleistocene
Age Terrace Deposits which are wide spread in coastal areas of Carlsbad. As exposed, site
Terrace Deposits typically consist of red brown colored sandstone deposits that occur in
massive and medium dense to dense conditions near surface. Deeper exposures in Boring
1 (B-1) also encountered local "running sand" layers that are characterized by "clean"
cohesionless granular deposits that resulted in caving within the borehole. Based on our SPT
blow counts, the "running sand" layers occur in a tight condition overall and are local
intermittent occurrences. Below the "running sand" layer, at a depth of approximately 15
feet, the sandstone changed to a dense tan to olive colored silty fine sandstone to sandy
siltstone at the depth of 18 feet, that may be a reflection of the Eocene Age Santiago
Formation which is known to be present beneath the Terrace Deposits (referenced Geosoils
report). Project dense sandstone/siltstone are considered stable, competent deposits that will
provide adequate support for new fills, structures, and improvements.
Artificial Fill ( af) -Surface areas of the property are mantled by a shallow fill deposit likely
placed during original and subsequent site development. As exposed, the fill deposits appear
to be locally derived silty sand deposits that were found in dry and very loose to compacted
conditions overall. Site existing fill deposits range to nearly 3 feet thick maximum, as
exposed in our test excavations.
Site existing fills and upper weathered loose Terrace Deposits are not suitable for structural
support in their present condition and should be removed and recompacted as outlined in
following sections.
B. Groundwater and Surface Draina2e
Subsurface water was not encountered in our test excavations to the depths explored and is
not expected to impact site development as planned. Like all graded properties, the proper
control of surface drainage is an important factor in the continued stability of the project
redevelopment. Surface water should not pond upon graded surfaces, and irrigation water
should not be excessive. Drainage ditches should be provided at the top of graded slopes and
all site retaining walls should be provided with a well-functioning back drain system.
C. Slope Stability
The western perimeter graded slope, apparently constructed during the original site
development more than 25 years ago, descends from the rear of the property to the Buena
Vista Lagoon embankment below. Slope heights are nearly 40 feet with gradients
approaching 2: 1. The slope is provided with level terraces, nearly 4 feet wide, as shown on
the enclosed Figure 2. There is no indication of slope instability and rear hillside appear to
continue performing well in its present condition.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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Slope analysis was performed by Geosoils, Inc. for the purpose of the development on the
neighboring property (referenced report). Their analysis concluded overall gross and
surficial conditions of stability for both static and pseudo-static conditions. Furthermore, the
rear swimming pool development near the top of the descending hillside is recommended
herein for support on a concrete platform and drilled CIP caissons to minimize ground
disturbance and impacts on the adjacent slope. Consequently, the planned rear yard
improvements and pool construction are not expected to have a significant impact or adverse
effect on the stability of the rear slope.
D. Faults/Seismicity
Faults or significant shear zones are not indicated on or in close proximity to the project site.
As with most areas of California, the San Diego region lies within a seismically 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 of 3. 7, nor did any of the earthquakes
generate more than modest ground shaking, and did not produce significant damages. Most
of the recorded events occurred along various offshore faults which characteristically
generate modest earthquakes.
Historically, the most significant earthquake events which affect local areas originate along
well known, distant fault zones to the east and 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 12 miles from the project area. This event, which is thought to have occurred
along an offshore fault, reached an estimated magnitude of 6.5 with estimated bedrock
acceleration values of 0.138g at the project site. The following list represents the most
significant faults that commonly impact the region. Estimated ground acceleration data
compiled from Digitized California Faults (Computer Program EQF AULT VERSION 3 .00
updated) typically associated with the fault is also tabulated.
TABLE 1
MAXIMUM
FAULT ZONE DISTANCE FROM SITE :PROBABLE
ACCELERATION <R.H.)
Rose Canyon Fault 5.1 miles 0.243g
Newport-Inglewood Fault 4.7 miles 0.252g
Elsinore-Julian Fault 24.1 miles 0.142g
Coronado Bank Fault 21.3 miles 0.184g
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
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The locations of significant faults and earthquake events relative to the study site are depicted
on a Fault -Epicenter Map attached to this report as Figure 8.
More recently, the number of seismic events that affect the region appears to have heightened
somewhat. Nearly 40 earthquakes of magnitude 3 .5 or higher have been recorded in coastal
regions between January 1984 and 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. An earthquake of magnitude
5.3 shook County coastal areas with moderate to locally heavy ground shaking resulting in
$700,000 in damages, one death, and injuries to 30 people. The quake occurred along an
offshore fault located nearly 30 miles southwest of Oceanside.
A series of notable events shook County areas with a (maximum) magnitude 7.4 shock in the
early morning of June 28, 1992. These quakes originated along related segments of the San
Andreas Fault approximately 90 miles to the north. Locally high levels of ground shaking
over an extended period of time resulted; 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 that can be expected at the study site as a result of seismic
activity.
In recent years, the Rose Canyon Fault has received added attention from geologists. The
fault is a significant structural feature in metropolitan San Diego that includes a series of
parallel breaks trending southward from La Jolla Cove through San Diego Bay toward the
Mexican border. Test trenching along the fault in Rose Canyon indicated that at that location
the fault was last active 6,000 to 9,000 years ago. More recent work suggests that segments
of the fault are younger having been last active 1000 -2000 years ago. Consequently, the
fault has been classified as active and included within an Alquist-Priolo Special Studies Zone
established by the State of California. Furthermore, a more recent 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-Ingelwood/Rose Canyon fault offshore.
Although, an earthquake of this magnitude has likely not occurred in the 100,000 years,
according to the data.
Fault zones tabulated in the preceding table are considered most likely to impact the region
of the study site during the lifetime of the project. The faults are periodically active and
capable of generating moderate to locally high levels of ground shaking at the site. Ground
separation as a result of seismic activity is not expected at the property.
I
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
E. Seismic Ground Motion Values
October 2, 2017
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Seismic ground motion values were evaluated as part of this investigation in accordance with
Chapter 16, Section 1613 of the 2016 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, S1), Risk-Targeted Maximum
Considered Earthquake (MCER) adjusted for Site Class effects (SMs, SM1) and Design (Sos,
Sm) Spectral Acceleration Parameters as well as Site Coefficients (Fa, Fv) for short periods
(0.20 second) and I-second period, Site Class, Design and Risk-Targeted Maximum
Considered Earthquake (MCER) Response Spectrum, Mapped Maximum Considered
Geometric Mean (MCEo) Peak Ground Acceleration adjusted for Site Class effects (PGAM)
and Seismic Design Category based on Risk Category and the severity of the design
earthquake ground motion at the site are summarized in the enclosed Appendix.
F. Geologic Hazards
Geologic hazards are not presently indicated at the project site. 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.
G. Field and Laboratory Tests and Test Results
Earth deposits encountered in our exploratory test excavation were closely examined and
sampled for laboratory testing. Based upon our exploratory boring and field exposures site
soils have,been grouped into the following soil type:
TABLE2
Soil Tiee I Descrietion I
I Brown to red brown silty sandy (Fill/Terrace Deposits)
2 Tan grey to off-while coarse sand with pebbles (Terrace Deposits)
3 Tan to olive silty fine sandstone to sandy siltstone (May be Santiago Formation)
The following tests were conducted in support of this investigation:
1. Standard Penetration Tests: Attempts were made to perform Standard Penetration
Tests (SPT), at selected depths, at the time ofborehole drilling in accordance with ASTM
standard procedw-e 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 5-foot long
I
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Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
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ML drill rods. The bore hole was 150 MM ( 6 inches) in diameter and water was locally
used 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 on a representative sample of
Soil Type 1. The test results are graphically presented on the attached Figure 9 and
tabulated in Table 3 below.
TABLE3
Sieve Size I 2" 1½" 1" ¾" ½" #4 #10 #20 #40 #100 #200
Location I Soil Type II Percent Passing
TP-1 @2.5' 1 100 100 100 100 100 99 98 84 32 25
B-1ca210' 2 100 100 100 99 95 85 70 54 9 6
3. Maximum Dry Density and Optimum Moisture Content: The maximum dry density
and optimum moisture content of Soil Type 1 was determined in accordance with ASTM
D-1557. The results are presented in Table 4.
TABLE4
Location Soil MaximumDry Optimum Moistur.e
Type Density (r m-pcf) Content (<a>opt-%)
TP-1 (@. 2.5' 1 132.9 9
4. Unit Wei2ht & 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 D2216. The test results are presented in Table 5 and tabulated on the
attached Boring Logs at corresponding locations.
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Limited Geotechnical Investigation, Proposed New Building Additions
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TABLES
Sample Soil Field Moisture Field Dry Max.Dry In-Place Degree of
I.;ocation Type Content Density Density Relative Saturation
(6.)-o/o) (Td-pcf) (Tm-pcf) C.ompaction 8(%),
TP-1@ l' 1 5 112.6 132.9 85 29
TP-1 @ 2.5' 1 7 116.2 132.9 87 44
B-1 @3' 1 3 119.8 132.9 90 20
B-1 @6' 1 3 -132.9 SPT Sample -
B-1@ 10' 2 3 --Sample Disturbed -
B-1@ 18' 3 13 --SPT Sample -
B-2@2.5' 1 6 -+ 132.9 Sample Disturbed -
B-2@5' 1 6 --SPT Sample -
B-3@ l' 1 ---No Sample Recovery -
B-3 @2' 1 5 --SPT Sample -
Assumptions and relationships:
In-place Relative Compaction = (Yd+ Ym) Xl00
Gs = 2.70
e = (Gs Yw + Yd) -1
S =(wGs)+e
5. Expansion Index Test: One expansion index (El) test was performed on a
representative sample of Soil Type 1 in accordance with the ASTM D-4829. The test
results are presented in Table 6.
TABLE6
Sample Soil Molded Degree of Final Initial Dry Measured EI
(,) Saturation (,) Density 50% Location Type (%) Wo) (o/o) (PCF.) EI Saturation
TP-1 @2.5' I 1 I 8 I 44 I 15 I 114 I 0 I 0 I
( w) = moisture content in percent.
Elso = Elmeas -(50 -Smeas) ((65 + Elmeas) + (220 -Smeas))
Expansion Index (EI) Expansion Potential
0 -20 Very Low
21 -50 Low
51 -90 Medium
91 -130 High
) 130 Very High
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and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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6. Direct Shear Test: One direct shear test was performed on a representative sample of
Soil Type 1 in accordance with ASTM D3080. 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 in Table 7.
TABLE7
Sample Soil Sample Unit Angle of Apparent
Weight Int. Frie. Cohesion Location Type Condition (rw-pcf) (~-De!!.) (c-osf)
TP-1 (@. 2.5' 1 Remolded to 100% of in-place condition 127.0 38 273
7. pH and Resistivity Test: pH and resistivity of a representative sample of Soil Type 1
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.
TABLES
I Sample Location Soil TyPe Minimum Resistivity (OHM-CM) pH
I TP-1 @2.5' 4500 7.1
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I
8. Sulfate Test: A sulfate test was performed on a representative sample of Soil Type 1 in
accordance with the California Test Method (CTM) 417. The test result is presented in
Table 9.
TABLE9
Sample Location Soil Ty,pe Amount of Water Soluble Sulfate
In Soil(% by Weight)
TP-1 @2.5' I 1 I 0.001
7. Chloride Test: A chloride test was performed on a representative sample of Soil
Type 1 in accordance with the California Test Method (CTM) 422. The test result is
presented in Table 10.
TABLEl0
Sample Location Soil Type Amount of Water Soluble Ghloride
In Soil (% by Weight)
TP-1 @ 2.5' I 1 I No Detection
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Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
VI. SITE CORROSION ASSESSMENT
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A site is considered to be corrosive to foundation elements, walls and drainage structures if one or
more of the following conditions exist:
* Sulfate concentration is greater than or equal to 2000 ppm (0.2% by weight).
* Chloride concentration is greater than or equal to 500 ppm (0.05 % by weight).
* pH is less than 5.5.
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 minimum resistivity value for soil ( or water)
less than 1000 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
sulfate), pH levels and the desired service life of the structure.
Results oflimited laboratory tests performed on selected representative site samples indicated that
the minimum resistivity is greater than 1000 ohm-cm suggesting presence of low quantities of
soluble salts. Test results further indicated that pH levels are greater than 5.5, sulfate concentration
are less than 2000 ppm and chloride concentration levels are less than 500 ppm. Based on the results
of the corrosion analyses, the project site is considered non-corrosive. However, the project site is
located in a close proximity to seawater and corrosion mitigation measures should be considered in
the project designs, unless otherwise approved. Corrosion mitigation typically includes special high
strength concrete, zinc or epoxy coated reinforcing steel and greater reinforcement cover, as required
and appropriate.
Based upon the result of the tested soil sample, the amount of water soluble sulfate (SO4) was found
to be 0.001 percent by weight which is considered negligible according to AC! 318 (SO Exposure
Class with Not Applicable severity). However, due to the project close proximity to seawater, as a
minimum, Portland cement Type II with a minimum 28 days compressive strength (f c) of 4,000 psi
and maximum water cement ratio of 0.50 (SI Exposure Class) should be considered, unless
otherwise determined or approved by the project corrosion/structural engineer.
VII. CONCLUSIONS
Based upon the foregoing investigation, the proposed building additions and rear site improvements,
substantially as proposed, are feasible from a geotechnical viewpoint. The property is underlain by
stable Terrace Deposits at shallow depths and instability or adverse geologic conditions that could
preclude the proposed new additions and site improvements are not indicated.
Geotechnical factors presented below are unique to the project site and will most influence the
planned new construction and associated costs:
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* Landslides, hillside instability, faults or significant shear zones are not present at the project
property and are not considered a major geotechnical factor in the planned new construction.
The study site is not located within the Alquist -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.
* The project property is a developed parcel created over 25 years ago and currently supports
an existing residential dwelling with the associated structures and improvements. Building
additions and modifications were also apparently carried out subsequent to the original
development. Records of engineering plans, observation and testing services during the
original development and subsequent additions and building modifications are not available.
* The property is underlain at shallow depths by stable and competent Pleistocene Age
sandstone Terrace Deposits, which will provide adequate support for the planned new
additions and site improvements.
* Shallow artificial fills, on the order of 3 feet thick maximum, mantle the project site.
Existing site fills occur in dry and very loose to somewhat compacted conditions overall, and
are not considered suitable for structural support. These deposits should be removed and
recompacted as a part of foundation bearing and subgrade soil preparation. As an alternative,
new foundations may penetrate these deposits and adequately extend into the underlying
dense Terrace Deposits as recommended in the following sections.
* Evidence of a deep-seated or surficial instability which could preclude the planned backyard
improvements and swimming pool construction is not indicated within the site rear
descending slope. All structures and improvements planned near or at the top of the rear
descending slope should be setback or provided with deepened foundations to provide an
adequate setback to daylight as specified herein.
* The main geotechnical concern at the site is the proximity of the planned new swimming
pool at the top of the rear slope. The project property is subject to string-line setback
requirements, and the City of Carlsbad Hillside Development Ordinance. In order to
minimize significant ground disturbance and construction grading impacts on the adjacent
descending hillside, the new swimming pool is recommended herein for support on a
concrete platform and drilled CIP caissons. New site improvements will also be located on
the east side of the existing retaining wall along the top of the rear slope. Consequently, the
planned new rear yard improvements and pool construction are not expected to have a
significant impact or adverse effect on the stability of the rear slope, provided our
recommendations are followed.
The imaginary 0. 7: 1 (horizontal to vertical) building setback plane from the top of slope, as
required by the City of Carlsbad is also shown on the enclosed Figures 2 and 7.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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* Specific recommendations for the swimming pool caisson and concrete platform support are
provided in the following sections. CIP caissons should be adequately extended a minimum
of IO feet or %-height of the adjacent hillside, whichever is more but need not to exceed 40
feet, horizontal distance between the bottom outside edge to daylight. Due to the existence
of"running sand" beneath the planned pool area, all caissons should be provided with casing
to protect the boreholes from caving.
* Final grades for the new building extensions will be at or very near existing grades and
significant groung modifications or major grading efforts are not planned in connection with
the project construction. Project earthworks are expected to primarily consist ofremedial
foundation bearing and subgrade preparations and minor filling for achieving the rear yard
improvement finish subgrade levels.
* Existing building foundations were locally exposed in our exploratory test pit excavations
TP-1 (see Figure 2). Based on our limited exposures, the existing foundation was measured
approximately 9 inches deep (BGS) and roughly 12 inches wide. Existing building
foundations are not suitable for second story loading conditions and foundation underpinning
will be required where second floor additions are planned, as specified in the following
sections.
* Site soils are chiefly sandy to silty sand (SP/SM) deposits with very low expansion potential
(expansion index less than 20) based on ASTM D-4829 classification, and expansive soils
are not considered a geotechnical factor in the planned new constructions.
* Added care will be required to avoid undermining or cause any damages to the nearby
existing structures and improvements, adjacent neighboring properties and underground
utilities due to site excavations, earthworks, grading and construction activities. Adequate
excavation setbacks shall be maintained and temporary construction slopes laid back as
specified herein. Added field recommendations, however, may also be necessary and should
be given by the project geotechnical consultant for the protection of adjacent properties and
should be anticipated.
* Groundwater conditions were not encountered during this investigation to the depths
explored and are not expected to impact the proposed new additions and site improvements.
However, adequate site surface drainage control is a critical factor in the future stability of
the redeveloped property, as planned. Drainage facilities should be designed and installed
for proper control and disposal of surface runoff. Surface water should flow away from the
project structures/improvements and top of the rear slope. Presence of an adequate back
drainage system behind the existing western margin retaining wall should be confirmed and
all new retaining walls provided with a well-functioning back drainage system as
recommended herein.
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and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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* Soil collapse and post construction total and differential settlements are not expected to be
a geotechnical factor in the development of the project site provided our remedial grading
and foundation recommendations are incorporated into the design and construction of the
project. Post construction settlement after completion ofremedial efforts and site grading
works as specified herein, is not expected to exceed approximately 1-inch and should occur
below the heaviest loaded footings. The magnitude of post construction differential
settlement as expressed in terms of angular distortion is not anticipated to exceed ½-inch
between similar adjacent structural elements.
* Liquefaction and seismically induced settlements will not be a factor in the planned new
construction provided our remedial foundation bearing and subgrade soil preparation, and
foundation recommendations are followed.
* Minor cracking and separation may be anticipated between the new additions and existing
adjacent building to remain. Improvements to such normal features for this type of
construction can be made by tying the existing building to the new additions as
recommended in the following sections.
VIII. RECOMMENDATIONS
The following recommendations are provided based on the available geotechnical data generated
during this limited effort, and scheme of the proposed building addition and rear site improvements,
as understood. Added or modified recommendations may also be appropriate and should be
provided by the project geotechnical consultant at the time of final plan review phase, and should
be anticipated:
A. Foundation Bearin2 and Sub2rade Soil Preparation
Major grading efforts or significant ground modifications are not planned in connection with
the proposed new building additions and site improvements. However minor remedial
bearing and sub grade soil preparations and grading is expected to achieve design grades and
construct safe and stable building and improvement surfaces. All site excavations, remedial
grading, earthworks, construction, and bearing/subgrade soil preparation 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 building addition construction site should be thoroughly potholed, identified
and marked prior to the initiation of the actual remedial grading and earthworks. Specific
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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geotechnical engineering recommendations may be required based on the actual field
locations and invert elevations, backfill conditions and final grades in the event of a
remedial grading conflict.
Utility lines may be needed to be temporarily redirected, if necessary, prior to
excavations and earthwork operations, and reinstalled upon completion of remedial
grading. Alternatively, permanent relocations may be appropriate as shown on the
approved plans.
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
bearing and subgrade soils. Voids created by the removals of the abandoned
underground pipes, tanks, structures, roots, and stumps should be properly backfilled
with compacted fills in accordance with the requirements of this report.
2. Clearing and Grubbing: Remove all existing surface and subsurface structures and
improvements, concrete flatwork and old foundations, vegetation, lawns, roots, stumps,
and all other unsuitable materials and deleterious matter from all areas proposed new
construction areas plus a minimum of 3 feet outside the perimeter envelop, 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
backfills.
The prepared grounds should be observed and approved by the project geotechnical
consultant or his designated field representative prior to grading and earthworks.
3. Stripping and Removals: Minor remedial and grading efforts will be required to
establish final design grades and construct safe and stable building addition and
improvement surfaces, and achieve final design grades. All existing loose and dry fills
and upper weathered Terrace Deposits in areas of planned new fills, building additions,
structures and site improvements plus a minimum of 3 feet outside the perimeter
envelop, where possible and as directed in the field, should be stripped (removed) to the
underlying dense Terrace Deposits, as approved in the field, and placed back as properly
compacted fills. Based on our available subsurface exposures, removal depths are
expected to be on the order of 1 to 3 feet deep maximum below the existing ground
surfaces (BGS). However, locally deeper removals may also be necessary and should be
anticipated. Bottom of all removals should be additionally ripped, prepared and
recompacted as part of the initial fill lift placement.
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There should be at least 12 inches of compacted fills under all new slab-on-grade floors,
however, all new building addition foundations should penetrate the upper fills and be
adequately embedded into dense undisturbed Terrace Deposits as approved in the field.
In the areas where dense and competent Terrace Deposits are not exposed (in-place
densities less than 87%) at the bottom of foundation trenches, if any encountered, the
bottom of the foundation excavation should be over-excavated to a minimum depth of
12 inches and reconstructed with well-compacted (minimum 90%) fills, as directed in
the field.
There should also be a minimum of 12 inches of compacted fills below rough finish
subgrade in the planned site improvement areas, as approved in the field. The exposed
bottom of all removals should be observed and approved by the project geotechnical
consultant or his designated field representative.
4. Temporary Construction Slopes and Trenching: Excavations and removals adjacent
to the existing foundations, improvements and structures should be performed under
observations of the project geotechnical engineer. Undermining existing adjacent
foundations, structures, improvements and underground utilities to remain shall not be
allowed by the project removals, over-excavations and earthwork operations.
Large open excavations, trenching and temporary construction slopes are not anticipated
in connection with the planned construction and new building additions. Project
excavations, trenching and temporary slopes are expected to be on the order of 3 feet
deep maximum.
Temporary excavations and trenching adjacent to existing foundations may be developed
in limited alternating sections not more than 12 feet long, unless otherwise approved.
Alternatively, temporary foundation support consisting of hydraulic jacks and
beams/plates ( or similar techniques) may be used to prevent undermining existing
foundations. Temporary jack and beams/plates foundation supports should have a
minimum 2000 pounds capacity and installed at 6 feet on centers maximum, unless
otherwise directed in the field.
All excavations, trenching and temporary construction slopes will require geotechnical
observations during the earthworks and construction operations. Additional
recommendations including revised excavation slopes and setbacks, completing
trenching and construction in more limited alternating sections, and the need for
modified temporary foundations support method should be given at that time as
necessary. The project contractor shall also obtain appropriate permits, as needed, and
conform to Cal-OSHA and local governing agencies ' requirements for trenching and
open excavations, as well as safety of the workmen during construction.
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and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
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5. Fill-Backfill Materials, Import Soils and Compaction: Soils generated from site
stripping (removals) and over-excavations will mainly consist of sandy materials that
typically work well as site new fills and backfills provided all debris, roots, rootles,
stump and unsuitable materials are throughly removed and separated to the satisfaction
of the project geotechnical consultant.
Import soils, if necessary to complete grading and achieve final design grades, should be
good quality sandy granular D.G. type (SM/SW), non-corrosive deposits 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 less than 20). Import soils
should be observed, tested as necessary, and approved by the project geotechnical
engineer prior to delivery to the site. Import soils should also meet or exceed engineering
characteristic and soil design parameters as specified in the following sections.
Uniform bearing and subgrade soil conditions should be constructed at the site by the
remedial grading operations. Site soils should be adequately processed, thoroughly
mixed, moisture conditioned to above (2%) optimum moisture levels, as directed in the
field, placed in thin (8 inches maximum) uniform horizontal lifts and mechanically
compacted to minimum 90% of the corresponding laboratory maximum dry density per
ASTM D1557, unless otherwise specified.
6. Surface Drainage and Erosion Control: A critical element to the continued stability
of regraded building addition pad and site improvement surfaces is an adequate
stormwater and surface drainage control.
Presently, existing site drainage is considered poor to marginal. In general, perimeter
drainage should be improved disallowing surface water to pond on pad surfaces or flow
toward the building foundations or improvement sites. For this purpose, some fine or
contour grading of the perimeter yards appear necessary to establish positive drainage
(minimum 5%) away from the site building and improvements onto a suitable drainage
collection and disposal facility. Roof gutters and area drains should be installed. Over-
watering of the site landscaping and lawns shall also not be allowed. Only the amount
of water to sustain vegetation life should be provided. A back drainage behind the
existing western wall should be field verified and new retaining walls provided with a
well-constructed back drainage system. Site drainage improvements should be shown
on a site/drainage improvement plan prepared by the project design consultant.
7. Engineering Observations: All bearing and subgrade soil preparation and earthwork
operations including excavations, stripping and removals, suitability of earth deposits
used as new compacted fills and backfills, and compaction procedures should be
continuously observed and tested by the project geotechnical consultant and presented
in the final as-graded compaction report. The nature of finished bearing and subgrade
soils should be confirmed in the final compaction report at the completion of grading.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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Geotechnical engineering observations should include but not limited to the following:
* Initial Observation/Preconstruction Meeting -After the site clearing and staking of
project building addition limits but before over-excavation/brushing starts.
* Bottom of Over-Excavation and Stripping (Removal) Observation -After completion
of over-excavation to the specified depth but before filling or backfilling.
* Temporary Excavations and Trenching Observations -At the completion of the first
section of trenching adjacent to existing foundations to evaluate exposed bearing soil
conditions at existing foundations and the need for hydraulic jack and beam/plate
support system.
* Fill/Backfill Observation -After the fill/backfill placement is started over the
approved bottom, but before the vertical height of fill/backfill exceeds 2 feet. All
new fills and backfills should be compacted to minimum 90% compaction levels,
unless otherwise approved. A minimum of one test shall be required for each 2 feet
in vertical gain. Finish rough and final pad grade tests shall be required regardless
of fill thickness.
* Foundation Trench and Subgrade Soils Observation -After the foundation trench
excavations and prior to the placement of steel reinforcing for adequate foundation
embedment depth to dense and competent undisturbed Terrace Deposit bearing strata,
and proper subgrade moisture and specified compaction levels, as appropriate.
* Geotechnical Foundation/Slab Steel Observation -After the steel placement is
completed but before the scheduled concrete pour.
* Underground Utility/Plumbing and Storm Drain 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 apply. Observations and testing of pipe bedding may also be required
by the project geotechnical engineer.
* Underground Utility/Plumbing and Storm Drain Trench Backfill Observation -After
the backfill 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 the governing agencies. Pipe bedding and backfill materials and
compaction level shall conform to the governing agencies' requirements and project
soils report, where and as applicable. All trench backfills should be mechanically
compacted to a minimum of 90% compaction levels unless otherwise specified.
Plumbing trenches 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 compaction method should not
be allowed.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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* Improvement Subgrade Observation -Prior to the placement of concrete for proper
subgrade preparations and specified compaction levels.
B. Footings and Slab-on-Grade Foundations
The following recommendations are consistent with the anticipated sandy to silty sand (SP /SM)
bearing soils with very low expansion potential ( expansion index less than 20), and site indicated
geotechnical conditions. All design recommendations should be further confirmed and/or
revised as necessary at the completion of remedial bearing and sub grade soil preparations and
presented in the final engineering observations and compaction testing report:
1. All new footings and underpinning grade beams, where necessary for the second floor
additions, should penetrate the upper fills, and adequately embedded into the underlying
dense and competent undisturbed Terrace Deposits, as approved in the field. In the areas
where dense and competent Terrace Deposits are not exposed at the minimum specified
depths (in-place densities less than 87%, if any encountered), the bottom of the
foundation and underpinning grade beam trench should be over-excavated to a minimum
depth of 12 inches and reconstructed with minimum 90% compacted fills, as evaluated
and directed in the field.
2. New perimeter and interior continuous strip footings should be sized at least 15 inches
wide and embedded a minimum of 18 inches into dense and competent undisturbed
Terrace Deposits, as approved in the field, for single and two-story building loading
conditions. Spread pad footings, if any, should be at least 24 inches square and also
embedded 18 inches into approved undisturbed Terrace Deposits. Based on the available
subsurface exploratory excavations, total foundation and underpinning grade beam trench
depths on the order of 2 to 3.5 feet may be anticipated. Exterior continuous footings
should enclose the entire perimeter.
Perimeter continuous wall foundations should be reinforced by at least four #5
reinforcing bars. Place a minimum of two #5 bars 3 inches above the bottom of the
footing and a minimum of two #5 bars 3 inches below the top. Reinforcement details for
spread pad and isolated post footings should be provided by the project
architect/structural engineer.
Existing perimeter footings should be tied near the top and bottom to the new adjacent
continuous footings with a minimum 18 inches long #4 dowels with minimum 6 inches
deep drill and epoxy grout to existing footings and 12 inches into new footings. New
interior continuous strip and spread pad footings, if any, should also be structurally tied
to the adjacent existing concrete floor slabs with minimum 18 inches long #4 dowels
spaced at 18 inches on centers maximum, drill and epoxy grouted at least 6 inches into
surrounding slabs and 12 inches into new footings, unless otherwise specified or noted.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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3. Interior slabs should be a minimum of 5 inches in thickness reinforced with minimum
#4 reinforcing bars spaced 18 inches on center maximum each way placed mid-height
in the slab. Provide re-entrant comer reinforcement for all interior slabs depending on
slab geometry and/or interior column locations, as generally depicted on the enclosed
Figure 10. Interior slabs should be provided with a well-performing moisture
barrier/vapor retardant (minimum 10-mil Stego) placed over the prepared sub grade and
covered with minimum 2 inches of clean sand (SE 30 or greater). Alternatively, a 4-inch
thick base of compacted ½-inch clean aggregate provided with the vapor barrier
(minimum 15-mil Stego) in direct contact with (beneath) the concrete may also be
considered provided a concrete mix which can address bleeding, shrinkage and curling
is used.
New interior slabs adjacent to existing footings/slabs, if any, should also be provided
with a minimum 12 inches wide by 12 inches deep thickened edge reinforced with a
minimum 1-#4 bar top and bottom, and tied at same spacing with the slab reinforcement,
with #4 dowels as previously specified.
Provide "softcut" contraction/control joints consisting of sawcuts spaced 10 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 sawcuts
should be minimum I-inch in depth but should not exceed 1 ¼-inches deep maximum.
Anti-ravel skid plates should be used and replaced with each blade to avoid spalling and
raveling. A void wheeled equipments across cuts for at least 24 hours.
4. Adequate setback or deepened foundations shall be required for all foundations and
improvements constructed on or near the top of descending slopes to maintain a
minimum horizontal distance to daylight or adjacent slope face. For foundations and
structural elements, there should be a minimum of 10 feet or % of the slope height,
whichever is more, horizontal setback from the bottom outside edge of the footing to
daylight, unless otherwise specified or approved. For site on-grade improvements, a
minimum of 7 feet horizontal setback from the outside edge ofimprovement to daylight
may be considered adequate, unless otherwise noted. For this purpose, site
improvements should also be provided with a reinforced thickened edge to satisfy the
minimum daylight setback requirement.
5. 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 geotechnical consultant prior to the placement of concrete.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
C. Underpinning Grade Beam
October 2, 2017
Page 21
Based on our test pit exposures, existing building foundations are undersized for the support of
a second story. Underpinning of the existing undersized footings, or a new independent
foundation system in accordance with the requirements of this report will be necessary, where
the second story building additions are planned. The following are appropriate in case of
underpinning the existing undersized footings:
1. Existing foundations, at the project second floor building additions, should be
underpinned with a new grade beam foundation member that extend into the underlying
dense and competent undisturbed Terrace Deposits, per the requirements of this report.
The new underpinning grade should be structurally tied into the existing footings. A
schematic of an underpinning grade beam is included in this report as Typical Grade
Beam Detail For Underpinning Wall Footings, Figure 11 .
2. The underpinning grade beam should at least 6 inches wide at the top and extend below
the entire width of the existing footings (minimum 18 inches), as shown in Figure 11 .
3. The grade beam should be reinforced with minimum 2-#4 bars top and bottom and #3
ties at 18 inches on centers maximum. The underpinning grade beams should also be
tied to the existing footings with minimum 26 inches long dowels drill and epoxy grout
6 inches into the existing footings and 10 inches into the new grade beam. Specific
designs and actual construction details should be provided by the project structural
engineering consultant.
4. Trenching for new grade beams and temporary support for existing foundations
consisting of hydraulic jacks and beams/plates (or approved similar) should be carried
out per the requirements of this report, and as approved in the field.
D. Soil Design Parameters
The following soil design parameters are based upon tested representative samples of onsite
earth deposits and our experience with similar earth deposits near the project site. All
parameters should be re-evaluated when the characteristics of the final as-graded soils have
been specifically determined:
* Design soil unit weight= 127 pcf.
* Design angle of internal friction of soil = 38 degrees.
* Design active soil pressure for retaining structures = 31 pcf (EFP), level backfill,
cantilever, unrestrained walls.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
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* Design at-rest soil pressure for retaining structures = 48 pcf (EFP), non-yielding,
restrained walls.
* Design soil passive resistance for retaining structures= 450 pcf (EPP), level surface on
the toe side ( soil mass on the toe side extends a minimum of 10 feet or 3 times the height
of the surface generating passive resistance).
* Design passive soil pressure for retaining structures= 203 pcf (EFP), 2: 1 sloping down
ground surface on the toe side.
* Design coefficient of friction for concrete on soils = 0.45.
* Design net allowable foundation pressure (minimum 12 inches wide footing embedded
18 inches into competent undisturbed Terrace Deposit) = 2000 psf.
* Allowable lateral bearing pressure (all structures except retaining walls)= 200 ps£'ft.
Notes:
* Added lateral pressures caused by nearby foundations, improvements and surcharge
loading should also be considered in the project wall designs, as applicable and
appropriate.
* An additional seismic force due to seismic increments of earth pressure should also be
considered in the project designs, as necessary and where applicable. A seismic lateral
inverted triangular earth pressure of 20 pcf (EFP) acting at O. 6H (His the retained height)
above the base of the wall should be considered. Alternatively, seismic loading based
on Mononobe-Okake (M-0) coefficients may be considered for seismic force due to
seismic increments of earth pressure as follows:
Kh = 0.16
Ka =0.24
Kae= 0.40
The seismic lateral earth pressure should be considered in addition to the specified static
earth and surcharge loading pressures.
* Use a minimum safety factor of 1.5 for wall over-turning and sliding stability. However,
because large movements must take place 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 passive pressure and frictional resistance, the passive component
should be reduced by one-third.
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and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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* The net allowable foundation pressures provided herein were determined based on
minimum 12 inches wide footings embedded at least 18 inches into dense and competent
undisturbed Terrace Deposits, 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 herein also apply to dead plus live loads and
may be increased by one-third for wind and seismic loading.
* The lateral bearing earth pressures may be increased by the amount of designated value
for each additional foot of depth to a maximum 1500 pounds per square foot.
E. Swimmin~ Pool Construction
The new swimming pool development is planned at the top of the rear descending hillside
underlain by shallow fills, on the order of 3 feet maximum, over dense Terrace Deposits.
The main geotechnical concern with respect to the pool construction is the close proximity
of the planned new swimming pool at the top of the hillside and conforming to the City of
Carlsbad Hillside Development Ordinance. In order to accommodate pool construction at
the top of descending hillside, minimize ground disturbances, and alleviate potential impacts
on the stability of the adjacent descending hillside, the new swimming pool is recommended
herein for support on a concrete platform and drilled CIP caissons.
Recommended swimming pool concrete platform and drilled CIP caisson support is
conceptually illustrated on the enclosed Typical Swimming Pool Construction Concept,
Figure 12. Detail design and construction plans for the proposed concrete platform and
caisson supports should be provided by the project design-build contractor or structural
engineer. The following parameters and minimum design values are based on the
engineering properties of the subsurface soil profile, as encountered during this study and our
experience with the similar projects in the vicinity of the project site and should be used in
the design, where applicable:
1. The new pool should be supported on a structural platform (slab). The concrete pool
shell should then be erected upon and structurally anchored and tied onto the concrete
platform. The concrete platform slab shall not be less than 12 inches minimum.
2. The space (void) between the bottom of the pool shell and top of the concrete platform
at the shallow end may be filled with Geofoam, 2.5-sack cement slurry, lightweight
concrete or similar fillers (see Figure 12).
3. The concrete platform slab should span over drilled CIP caissons which are adequately
embedded into the underlying competent Terrace Deposits to provide a minimum of20
feet setback from the bottom edge of the most outside caisson to daylight (% of the
hillside height), but not less 12 feet minimum.
Limited Geo technical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
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4. Drilled CIP caissons should a minimum of2 feet in diameter with no less than 2½ times
the diameter spacing, center to center. Maximum caisson spacing should not exceed 12
feet center to center, unless otherwise approved.
5. Point of fixity may be assumed at the depth of 2 feet into the underlying competent
undisturbed Terrace Deposits (minimum 5 feet below the top of slope). A passive
resistance of 450 psf may also be considered for the portion embedded below the point
of fixity. The passive resistance can be increased by the amount of the designated value
for each additional foot of depth to a maximum of 4500 psf.
6. A net allowable pile capacity of 1000 based on skin friction may be considered for dense
and competent Terrace Deposits (the weight ofthepilemaybe assumed to be supported
by end bearing. The net allowable pile capacity increase should be limited to a maximum
of depth of 20 times pile diameter).
7. A coefficient of friction of 0.45 may be considered for the portion of the caisson
embedded into the competent undisturbed Terrace Deposits. Use a minimum 4000 psi
(fc) concrete for CIP concrete caissons and platform.
8. Underlying Terrace deposits include intermittent layers of"running sand" layers that are
characterized by "clean" cohesionless deposits. Consequently, all caisson drill shafts
should be provided with casing to protect the boreholes from caving.
9. Groundwater was not encountered in our test borings to the depths explored. However,
subsurface water seeps may develop at the time of drilling and cannot be ruled out.
Water seeps, if developed, shall be properly removed using suitable dewatering
techniques from caisson shafts prior to concrete pour.
10. All shafts should be thoroughly cleaned to the satisfaction of the project geotechnical
engineer using a "clean out bucket." Free fall of concrete in the drill shafts shall not be
allowed. Concrete can be placed only upon the approval of the geotechnical engineer
using the "tremie" techniques. All drilled shafts shall be plumb. Drill shafts which are
more than 1 % of their height maximum out-of-plumb shall be rejected and required to
be re-drilled.
11. All caisson shafts should be observed and approved by the project geotechnical
consultant prior to the placement of steel cage and pouring the concrete.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
F. Exterior Concrete Slabs, Pool DeckinK, Patios and Flatwork
October 2, 2017
Page 25
1. All exterior slabs (walkways, patios) supported on very low expansive subgrade soils
should be a minimum of 4 inches in thickness, reinforced with #3 bars at 18 inches on
centers in both directions placed mid-height in the slab. The subgrade soils should be
compacted to minimum 90% compaction levels at the time of fine grading and before
placing the slab reinforcement.
In order to enhance performance of exterior slabs, pool decking and Flatwork, a
minimum 8 inches wide by 8 inches deep thickened edge reinforced with a minimum of
1-#4 continuous bar near the bottom should be considered along the slab perimeter.
2. Reinforcements lying on subgrade will 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
reinforcements are discontinued or cut at the construction joints, slab panels should be
tied together with minimum 18 inches long #3 dowels at 18 inches on centers placed
mid-height in the slab (9 inches on either side of the joint).
3. Provide "too] joint" or "softcut" contraction/control joints 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 ¾-inch but should not exceed I-inch deep maximum. In case
of softcut joints, 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.
Joints shall intersect free-edges at a 90° angle and shall extend straight for a minimum
of 1 ½ feet from the edge. The minimum angle between any two intersecting 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.).
4. Site improvements placed along the top of descending hillside should be provided with
a reinforced thickened edge to satisfy the minimum daylight setback requirement, as
specified in this report.
5. All exterior slab designs should be confirmed in the final as-graded compaction report.
6. Subgrade soils should be tested for proper moisture and specified compaction levels and
approved by the project geotechnical consultant prior to the placement of concrete.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
G. General Recommendations
October 2, 2017
Page 26
1. The minimum foundation design and steel reinforcement provided herein are based on
soil characteristics and are not intended to be in lieu of reinforcement necessary for
structural considerations.
2. Adequate staking and grading control is a critical 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 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 which will
increase construction costs.
3. Footings located on or adjacent to the top of descending slopes should be adequately
setback or extended to a sufficient depth to provide a minimum horizontal distance to the
slope face, as specified in this report. Site concrete flatwork and improvements near the
top of descending slopes should be provided with a thickened edge to satisfy this
requirement, as specified.
4. 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 footing.
5. 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.
6. Foundations where the surface of the ground slopes more than 1 unit vertical in 10 units
horizontal (10% slope) shall be level or shall be stepped so that both top and bottom of
such foundations are level. Individual steps in continuous footings shall not exceed 18
inches in height and the slope of a series of such steps shall not exceed 1 unit vertical to
2 units horizontal (50%) unless otherwise specified. The steps shall be detailed on the
structural drawings. The local effects due to the discontinuity of the steps shall also be
considered in the design of foundations as appropriate and applicable.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
Page 27
7. All underground utility and plumbing trenches should be mechanically compacted to a
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 the compaction of the soil.
Non-expansive, granular backfill soils should be used. Trench backfill materials and
compaction levels beneath pavements within the public right-of-way shall conform to the
requirements of governing agencies.
8. Expansive clayey soils should not be used for backfilling 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 13. Planting large trees behind
site building retaining walls should be avoided.
9. Site drainage over the finished pad surfaces should flow away from structures onto the
street in a positive manner. Care should be taken during the construction, improvements,
and fine grading phases not to disrupt the designed drainage patterns. Roof lines of the
buildings should be provided with roof gutters. Roof water should be collected and
directed away from the buildings and structures to a suitable location.
10. Final plans should reflect preliminary recommendations given in this report. Final
foundations and grading plans may also be reviewed by the project geotechnical
consultant for conformance with the requirements of the geotechnical investigation report
outlined herein. More specific recommendations may be necessary and should be given
when final grading and architectural/structural drawings are available.
11. This report is subject to review and possible revisions in the case of plan changes
particularly with respected to building additions and new improvement surfaces and final
locations, design finish grades and heights of retaining walls. Additional
recommendations and design parameters will also be necessary in case of added site
improvements and structures.
12. All foundation trenches should be observed to ensure adequate footing embedment and
confirm competent bearing soils. Foundation and slab reinforcements should also be
observed and approved by the project geotechnical consultant.
13. The amount of shrinkage and related cracks that occurs in the concrete slab-on-grades,
Flatwork and driveways depend on many factors the most important of which is the
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:
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
Page 28
IX.
* 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
(nearly 5-gal.) water per cubic yard than concrete with 1-inch aggregate.
* 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, craftsmanship, and control
tests where appropriate and applicable are provided.
14. 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.
GEOTECHNICAL ENGINEER OF RECORD (GER)
§1.16 Geotechnical Solutions, Inc. is the geotechnical engineer ofrecord (GER) for providing a
specific scope of work or professional service under a contractual agreement unless it is terminated
or canceled by either the client or our firm. In the event a new geotechnical consultant or soils
engineering firm is hired to provide added engineering services, professional consultations,
engineering observations and compaction testing, §1.16 Geotechnical Solutions, Inc. will no longer
be the geotechnical engineer of the record. Project transfer should be completed in accordance with
the California Geotechnical Engineering Association (CGEA) Recommended Practice for Transfer
of Jobs Between Consultants.
The new 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 §1.16 Geotechnical Solutions, Inc. and submit proper notification
to the City of Carlsbad for the assumption of responsibility in accordance with the applicable codes
and standards (1997 UBC Section 3317.8).
X. LIMITATIONS
The conclusions and recommendations provided herein have been based on available data obtained
from the review of pertinent reports and plans, limited subsurface exploratory excavations as well
as our experience with the soils and formational materials located in the general area. The materials
encountered on the project site and utilized in our laboratory testing are believed representative of
the total building addition area; however, earth materials may vary in characteristics between
excavations.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
October 2, 2017
Page 29
Of necessity, we must assume a certain degree of continuity underneath the planned construction
areas. It is necessary, therefore, that all observations, conclusions, and recommendations be field
verified during the project constructions and earthwork 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/contractor to ensure that these recommendations are
carried out in the field.
It is almost impossible to predict with certainty the future performance of a new building addition
to an existing older building. The future behavior of the new addition building pad is also dependent
on numerous unpredictable variables, such as earthquakes, rainfall, and on-site drainage patterns.
The firm of SlllS Geotechnical Solutions, Inc., shall not be held responsible for changes to the
physical conditions of the property such as addition of fill soils or changing drainage patterns which
occur without our observation or control.
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,
especially with respect to finish elevations, building additions and final improvements layout, this
report must be presented to us for review and possible revision.
This report is issued with the understanding 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
the project general contractor and subcontractors carry out such recommendations during
construction.
The project geotechnical engineer should be provided the opportunity for a general review of the
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
misinterpretation of his recommendations.
SlllS Geotechnical Solutions, Inc., warrants that this report has been prepared within the limits
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.
Once again, should any questions arise concerning this report, please do not hesitate to contact this
office. Reference to our Project No. GI-17-09-139 will help to expedite our response to your
mqmnes.
Limited Geotechnical Investigation, Proposed New Building Additions
and Rear Site Improvements, 2465 Jefferson Street, Carlsbad, California
We appreciate this opportunity to be of service to you.
SM§ Geotechnical Solutions, Inc.
Ste~<a~
CEG #2362
Distribution: Addressee (3, e-mail)
Andrew Carlos Architect (e-mail)
§.M§ GEOTECHNICAL SOLUTIONS. INC.
October 2, 2017
Page 30
REFERENCES
-Annual Book of ASTM Standards, Section 4 -Construction, Volume 04.08: Soil and Rock (I);
D420 -D5876, 2016.
-Annual Book of ASTM Standards, Section 4-Construction, Volume 04.09: Soil and Rock (II);
D5877 -Latest, 2016.
-Highway Design Manual, Caltrans. Fifth Edition.
-Corrosion Guidelines, Caltrans, Version 1.0, September 2003 .
-California Building Code (CBC), California Code of Regulations Title 24, Part 2, Volumes 1 &
2, 2016, International Code Council.
-"The Green Book" Standard Specifications For Public Works Construction, Public Works
Standards, Inc., BNi Building News, 2015 Edition.
-California Geological Survey, 2008 (Revised), Guidelines for Evaluating and Mitigating Seismic
Hazards in California, Special Publication 117 A, 108p.
-California Department of Conservation, Division of Mines and Geology (California Geological
Survey), 1986 (revised), Guidelines for Preparing Engineering Geology Reports: DMG Note 44.
-California Department of Conservation, Division of Mines and Geology (California Geological
Survey), 1986 (revised), Guidelines to Geologic and Seismic Reports: DMG Note 42.
-EQFAULT, Ver. 3.00, 1997, Deterministic Estimation of Peak Acceleration from Digitized
Faults, Computer Program, T. Blake Computer Services and Software.
-EQSEARCH, Ver 3.00, 1997, Estimation of Peak Acceleration from California Earthquake
Catalogs, Computer Program, T. Blake Computer Services and Software.
-Tan S.S. and Kennedy, M.P ., 1996, Geologic Maps of the Northwestern Part of San Diego
County, California, Plate(s) 1 and 2, Open File-Report 96-02, California Division of Mines and
Geology, 1 :24,000.
-"Proceeding ofThe NCEER Workshop on Evaluation of Liquefaction Resistance Soils," Edited
by T. Leslie Youd and Izzat M. Idriss, Technical Report N CEER-97-0022, Dated December 31 ,
1997.
-"Recommended Procedures For Implementation ofDMG Special Publication 117 Guidelines
For Analyzing and Mitigation Liquefaction In California," Southern California Earthquake
Center; USC, March 1999.
REFERENCES {continued)
-"Soil Mechanics," Naval Facilities Engineering Command, DM 7.01.
-"Foundations & Earth Structures," Naval Facilities Engineering Command, DM 7.02.
-"Introduction to Geotechnical Engineering, Robert D. Holtz, William D. Kovacs.
-"Introductory Soil Mechanics and Foundations: Geotechnical Engineering," George F. Sowers,
Fourth Edition.
"Foundation Analysis and Design," JosephE. Bowels.
Caterpillar Performance Handbook, Edition 29, 1998.
-Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas, California Division
of Mines and Geology, Geologic Data Map Series, No. 6.
Kennedy, M.P ., 1977, Recency and Character of Faulting Along the Elsinore Fault Zone in
Southern Riverside County, California, Special Report 131, California Division of Mines and
Geology, Plate 1 (East/West), l 2p.
-Kennedy, M.P. and Peterson, G.L., 1975, Geology of the San Diego Metropolitan Area,
California: California Division of Mines and Geology Bulletin 200, 56p.
-Kennedy, M.P. and Tan, S.S., 1977, Geology of National City, hnperial Beach and Otay Mesa
Quadrangles, Southern San Diego Metropolitan Area, California, Map Sheet 24, California
Division of Mines and Geology, 1 :24,000.
Kennedy, M.P., Tan, S.S., Chapman, R.H., and Chase, G.W., 1975, Character and Recency of
Faulting, San Diego Metropolitan Areas, California: Special Report 123, 33p.
-"An Engineering Manual For Slope Stability Studies," J.M. Duncan, A.L. Buchignani and
Marius De Wet, Virginia Polytechnic Institute and State University, March 1987.
-"Procedure To Evaluate Earthquake-Induced Settlements In Dry Sandy Soils," Daniel Pradel,
ASCE Journal Of Geotechnical & Geoenvironmental Engineering, Volume 124, #4, 1998.
i'Minimum Design Loads For Buildings and Other Structures," ASCE 7-10, American Society
of Civil Engineers (ASCE).
-"Seismic Constraints on The Architecture of The Newport-Ingelwood/Rose Canyon Fault:
Implications For The Length And Magnitude of Future Earthquakes," Sahakian, V., Bormann,
J.,Driscoll, N., Harding, A. Kent, G. Wesnousky, S. (2017), AGU. doi:10.1002/2016 JB 013467
1
MEAN HIGH WATER ELEVATION = 4.49·
DATE TAKE N: 11-09-2016
THIS MHW ELEVATION WAS DETERMINED BY
PROJECTING EXISTING SLOPE DATA GATHERED
ALONG THE UPLAN D AND SHORELINE AREA. NO~·
HARD BOTTOM DATA WAS GATHERED FOR THE
LAGOON AS PART OF THI S DATA. THE MHW
ELEVATION IS APPROXIMATE IN NATURE.
STRING LINE EXHIBIT
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KEY TO BORING/ TEST PIT LOGS
DRILLING & SAMPLING SYMBOLS:
B Split Spoon -1-3/8" 1.0., 2" 0.0., Unless otherwise noted HS: Hollow Stem Auger □ Chunk Sample
ST: Thin-Walled Tube -2" O.D., Unless otherwise noted PA: Power Auger T Sandcone Density Test
IZI Ring Sampler -2.375" 1.0., 2.5'' 0.0., Unless otherwise noted HA: Hand Auger
DB: Diamond Bit Coring -4", N, B RB: Rock Bit
■ Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary
The number of blows required to advance a standard 2-inch 0.0. split-spoon sample (SS) the last 12 inches of the total 18-inch penetration with a
140-pound hammer falling 30 inches is considered the "Standard Penetration" or "N-value". For 2.5" O.D. ring samplers (RS) the penetration value is
reported as the number of blows required to advance the sampler 12 inches using a 140-pound hammer falling 30 inches, reported as "blows per
foot" and is not considered equivalent to the "Standard Penetration" or "N-value".
WATER LEVEL MEASUREMENT SYMBOLS
WL: Water Level
WCI: Wet Cave in
DCI: Dry Cave in
AB: After Boring
WS:
WO:
BCR:
ACR:
While Sampling
While Drilling
Before Casing Removal
After Casing Removal
N/E: Not Encountered
Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other times and other
locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater. In low permeability soils, the
accurate determination of groundwater levels may not be possible with only short-term observation.
DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the unified classification system. Coarse Grained Soils have more than 50% of their
dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their
dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major
constituents may be added as modifiers and minor constituents may be added according to relative proportions based on grain size. In addition to
gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.
CONSISTENCY OF FINE-GRAINED SOILS
Unconfined Standard
Compressive Penetration or N-
Stren~h, gu, psf value (SS) Blows[Ft. Consisten9:
< 500 <2 Very Soft
500-1000 2 -3 Soft
1001-2000 4-6 Medium Stiff
2001 -4000 7-12
4001-8000 13-26
8000+ 26+
RELATIVE PROPORTION OF SAND AND GRAVEL
Descriptive Term(s) of other
Stiff
Very Stiff
Hard
RELATIVE DENSITY OF COARSE-GRAINED SOILS
Standard
Penetration or N-Ring Sampler (RSI
value (SS) Blows[Ft. Blows/Ft. Relative Densitl
0-3 0 -6 Very Loose
4-9 7-18 Loose
10-29 19-58 Medium Dense
30-49 59-98 Dense
so+ 99 + Very Dense
GRAIN SIZE TERMINOLOGY
constituents
Trace
With
Modifiers
Percent of Ory Weight
< 15
Major Component of Sample
Boulders
Particle Size
Over 12 in. (300 mm)
15-29
>30
RELATIVE PROPORTION OF FINES
Descriptive Term(s) of other
constituents
Trace
With
Modifiers
Percent of Dry Weight
< 15
15-12
>12
Cobbles
Gravel
Sand
Silt or Clay
Term
Non-plastic
Low
Medium
High
12 in. to 3 in. (300 mm to 75 mm)
3 in. to #4 sieve (75 mm to 4. 75 mm)
#4 Sieve to #200 Sieve (4.75 mm to 0.075 mm)
Passing #200 Sieve (0.075 mm)
PLASTICITY DESCRIPTION
Plasticity Index
0
1 -10
11 -30
30+
~~~ Geotechnical Solutions, Inc.
UNIFIED SOIL CLASSIFICATION SYSTEM (USCS)
Criteria for Assigning Group Symbols and Group Names Using Laboratory TestsA Soil Classification
Group Group Name Symbol
Gravels Clean Gravels Cu ~ 4 and 1 5 C. < 3' GW Well-graded gravel'
More than 50% of coarse Less than 5% fines' Not meeting above gradation for GW GP Poorly graded gravel'
Coarse Grained Soils fraction retained on #4 Gravels with Fines Fines classify as ML or MH GM Silty gravel'·•·"
More than 50% sieve More than 12% fines' Fines classify as CL or CH GC Clayey gravel'-0•"
retained on #200 Sands Clean Sands Cu~ 6 and 15 C. :S 3'
sieve* Less than 5% fines0 Not meeting above gradation for SW 50% or more of coarse Sands with Fines Fines classify as ML or MH
SW Well-graded sand'
SP Poorly graded sand1
SM Silty sandG·"·' fraction passes #4 sieve More than 12% fines0 Fines classify as CL or CH SC Clayey sandG,H)
inorganic Pl> 7 and plots on or above "A" line'
Silts and Clal£S Pl < 4 and plots below "A" line'
CL Lean clay•·~"'
ML SiltK.~M
Fine Grained Soils Liquid limit less than 50 organic Liquid Limit -oven dried
50% or more passes Liquid Limit -not dried
the #200 sieve• inorganic Pl plots on or above "A" line
Silts and Clal£S Pl plots below "A" line
<0.75 OL Organic clay'•'·"·•
Organic silt'·~"'-0
CH Fat clay'·'<"'
MH
Liquid limit 50 or more organic Liquid Limit -oven dried
Liquid Limit -not dried <0.75 OH Organic clay•-~M.P
Organic silt'-~"'-0
Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat
* For soils having 5 to 12 % passing the No. 200 sieve, use a dual symbol such as GW-GC.
A Based on the material passing the 3 in. (75 mm) sieve.
8 If field sample contained cobbles or boulders, or both, add
"with cobbles or boulders, or both" to group name.
c Gravels with 5% to 12% fines require dual symbols: GW-GM
well-graded gravel with slit, GW-GC well-graded gravel with
clay, GP-GM poorly graded gravel with silt, GP-GC poorly
graded gravel with clay.
0 Sands with 5% to 12% fines require dual symbols: SW-SM
well-graded sand with silt, SW-SC well-graded sand with
clay, SP-SM poorly graded sand with silt, SP-SC poorly
graded sand.
For classifications of fine-grained soils
and fine-grained fraction of coarse-
grained soils.
Equation of "A" line.
Horizontal at Pl=4 to LL=25.5, then
Pl=0.73 (LL-20).
Equation of "U" line.
Vertical at LL=16 to Pl=7, then
Pl = 0.9 (LL-8)
60
so
:::::-40
Cl.
X QJ
D
E 30 c
E V,
"' 1i: 20
10
7
4
0
If soil contains ?:15% sand, add "with sand" to group name.
G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM
H If fines are organic, add "with organic fines" to group name.
If soil contains ?:15% gravel, add "with gravel" to group name.
If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
If soil contains 15% to 29% plus No. 200, add "with sand" or "with gravel"
whichever is
If soil contains ?:30% plus No. 200 predominantly sand, add "sandy" to
group name.
M If soil contains ?:30% plus No. 200 predominantly gravel, add "gravelly" to
group name.
N Pl ?:4 and plots on or above "A" line.
0 Pl <4 or plots below "A" line.
Pl plots on or above "A" line.
0 Pl plots below "A" line
L H
0 10 16 20 30 40 50 60 70 80 90 100
I iquid lirnit (l l )
~~~ Geotechnical Solutions, Inc.
SM S Geotechnical Solutions, Inc. Test Pit: TP-1
PROJECT: Proposed Building Additions CLIENT: Carefree Holdinm;. LLC
PROJECT No.: Gl-17-09-139 PROJECT LOCATION: 2465Jefferson St. Carlsbad
Date Excavated: __ 9/_18/_1_7_ Logged By: ---=S=.J.=M:..:.... __
Equipment: _H~a,=dc....:-d=iQ=·------------------------------1
Remarks: No cavina. No aroundwater. Adia::a,t foundation: 9"± dAPn bv 12"± (?) wide.
t)
DEPTH ~8
(ft) ti:-'
(!) . ·-·.:: ..... :~··.
·.··:-· ·::·~>: /:: ,·:•:···.·
MATERIAL DESCRIPTION
Fl LL (aO:
. .-. .... Silty fine to mooium-grainoo said. Brown color. -_.:•.•:·:.-. Dry to
. · ... ·.·.-.·. danp. Blocky. Loose to mooium den93. /<·:;> ST-1
~ 1 )Vi 'TERRACE DEPOSITS(Qt)
...
,. ,• ..
•,·• ... . ·:-.. -:_. -:_.·, ..
•,•.' ..
Fine to mooi um-grai noo saidstone. Si I ty. Roo-brown
color. Weatheroo. Friable. Porous.
Some.vhat blocky at 1.5feet. Moderately canentoo.
Damp. Massive. M ooi um den93 to den93.
ST-1
I
SM
J 5 112.6 85 29
ISP/SM
t----"·,..;...:::? ..... :: :: ..... ~ _,__:: -----""""l'"l==:;-:::::i:-..:::=-=-=-...,.-r~:=-------]_J [ 7 116.2 87 44
tjOTIOm OT lest pit ac £.~ Teel.
■ BULK
SAMPLE □ CHUNK
DENSITY W DENSITY n GROUND T TEST ~ WATER FIGURE 3
SMS GEOTECHNICAL SOLUTIONS, INC.
PROJECT: Proposed Building Additions
Boring: B-1
CLIENT: Carefree Holdinas LLC
PROJECT No.: Gl-17-09-139 PROJECT LOCATION: 2465 Jefferson St. Carlsbad
DATE LOGGED: 9/20/2017 BOREHOLE DIA: ---6" LOGGED BY: S.J.M.
CONTRACTOR: -'-P~a=ci=fic~D~r=illi=ng~----DRILL METHOD: Tri-Pod Mounted Beaver Drill. Solid Stem Auoer.
SAMPLE METHOD: 140 LB. Hammer dronned 30-inches bv race & cathead. 5-Foot ML rods.
REMARKS: Some ca vino of the borehole at 1 0' and 15'. No oroundwater.
t}
bEPTH IC!)
(ft) ~g
(!)
--:·: :·.• ·.:
MATERIAL DESCRIPTION
Fl LL (af} :
Silty fine Scl"ld. Brown color. Dry. Loose to relatively
compact. Wci..er Wffi ooded to aid dri 11 i ng.
Dcrnp at 2 feet.
cti () cti ::i
SM
::, .. :-·. \ ST -1 1r1--1-r1";;:;;;;:!-----t-----t----t---t----t I.II 1111111! 30-50/3" 3 11s.a oo 20
-10 : ::::ti<.;:
..... 11 _ :_::::.-::.-:-:.::.:
..... 12-/MII .... . .... . •
..... 13_ ).\J:/
._ 14 _ ::::/(}::
-..
TERRACE DEPOSITS(Qt):
Fine-grained saidstone. Silty. Locally indudes
rounded pebbles. Red-brown color. Wea:hered.
Frici:>le. Massive. Wf£J<ly to moderately cemented.
Dense to very dense.
At 6 feet, very low cohesion (running said). Dry.
Continues medium dense.
ST-1
At 10 feet, running coa-seto medium-grained said.
"Clem". Tight. Moist to dry .
Semple disturbed cl.. 10 feet .
At 13 feet, becomes tai-gray to off-white color .
Continuescoa-se-grained said with rounded pebbles.
Moist a,d dense.
At 15 feet, cave-in. Grooes to dayey saidstone.
Conti nues off-white col or with rust-colored staining.
lndudesday binder.
ST-2
~my tine sanustoneto saioy si11scone. 1 a, to 011ve
color. Very dense to very tight. (May be&rlti~o
Formation?)
~ ............ .J....I...J._\ST-3 /
,__ ___ .... t:Sre:o=no=m,....,o:e.:,r-.:00=1ren=o...,1e,....,c1::r-ll1""""" l::l.o,....,r=ea:,..... ___ __,
a STANDARD IT! MODIFIED ■ BULK GROUND ~ PENETRATION 1AJ CALIFORNIA SAMPLE 5l.. WATER TEST SAMPLER -
SP/SM
i.X
SP/OC
8-10-11
(21)
50/6"
3
3
~/ML~ f--'~t----t---;---;!---t----t
36-50/6" 13
FIGURE 4
SMS GEOTECHNICAL SOLUTIONS, INC. Boring: B-2
PROJECT: Proposed Building Additions CLIENT: Carefree Holdinas. LLC
PROJECT No.: Gl-17-09-139 PROJECT LOCATION: 2465 Jefferson St .. Carlsbad
DATE LOGGED: 9/20/2017 BOREHOLE DIA: 6" LOGGED BY: S.J.M.
CONTRACTOR: Pacific Drilling DRILL METHOD: Tri-Pod Mounted Beaver Drill. Solid Stem Auaer.
SAMPLE METHOD: 140 LB. Hammer dro□□ed 30-inches bv rooe & cathead. 5-Foot ML rods.
REMARKS: No cavina. No aroundwater.
()
cli w id~ w ... ~'R ~/:: u.6
OEPTH ~(!) ic It' OCz O;:: MATERIAL DESCRIPTION ti oz ~~~ :::,_ ~~i lli,2.-(fl) ~g Vi ::; >-.J:::, -Z~ 1;:...: u1ai-;~-~ ... 100 00 (!) ::::) u ::;U oS: ocO
. :;;:; FILL (af):
I-1 -SM
. Silty fine sand. Light brown color. Dry to moist. Loose .... 2 :,•: . . : : to rela:ively comped . I . . ~ .:•·. -.-·._:•:. ... ST-1 IAi,,.l .JU/'t 0 . . . .... 3 . . ';, . : : :·-.-..:·
'•,•' ·,: .
TERRACE DEPOSITS (Qt): .. · ...
.... 4 .. . : : :,-..
·: ... :::~-: '.· ·. BP/SM
-5 _(/
. . Fine to medium-grained sa1dstone . Silty. Red-brown . : :
........ . .-:::-color . Moist to slightly moist. Very tight to very dense. . . ' ., ' Sanple disturbed ct 2.5 feet. ~ 13-15-15
::::.\
. : : 6 _6_ (30) . -. : :-·. ST-1 .·.· .,
'. tjOnom OT uurt::1101e a: o.o 1t:ltll.
B STANDARD !XI MODIFIED ■ BULK "SL GROUND PENETRATION CALIFORNIA FIGURE 5 TEST SAMPLER SAMPLE -WATER
SMS GEOTECHNICAL SOLUTIONS, INC.
PROJECT: Proposed Building Additions
Boring: B-3
CLIENT: Carefree Holdinas LLC
PROJECT No.: Gl-17-09-139 PROJECT LOCATION: 2465 Jefferson St .. Carlsbad
DATE LOGGED: 9/20/2017 BOREHOLE DIA: -----=-6"_ LOGGED BY: --=S=.J=.M=·----1
CONTRACTOR: ~P~a~c_ifi~c ~D~ril=lin~g~----DRILL METHOD: Tri-Pod Mounted Beaver Drill. Solid Stem Auaer.
SAMPLE METHOD: 140 LB. Hammer droooed 30-inches bv rooe & cathead. 5-Foot ML rods.
REMARKS: No cavina. No aroundwater.
<.J
bEPTH iC!l
(ft) ~ g
(!)
MATERIAL DESCRIPTION
Silty fine sand. Light brown color. Dry. Mooium denrn
to relc:tively comped.
ST-1
TERRACE DEPOSITS(Qt):
Fine to mooium-grainoo sandstone. Roo-brown color.
SI i ghtl y moist.
At 1 foot, no sa11ple recovery.
Very tight to very dense a,d cementoo. Weter a::!doo tc
aid drilling. Very slow to difficult drilling.
ST-1
tsouom OT uurt:i1101e a: J.o Tee(.
1iii::jji STANDARD !Tl MODIFIED ■ BULK ~ PENETRATION 1AJ CALIFORNIA SA.MPLE TEST SA.MPLER
D GROUND
-¥-WATER
w ui !C~ <..i 0 ::!: >-1}j I-:::>
SM
-
SM -
(/) WI-.... _
:ii: I-ll:z ~] oz ~~* _,:, -Z-~~ mo 00 (.) ::;<.> c:i:
OU/'L
OU/4 0 u
FIGURE 6
~ u.5 O;::
~l ~~at (!):,-w C ~~
--
SCALE: l" = 10'
EXT'G WALL 70
~
60 60
50---'---~T_'E~CE D_EPQSIT [Qt] 50
40 40
SANTIAGO FORMATION {Tsa]?
30 30
-~--
20 1 20
10 10
FIGURE 7
..
\
\ ' ..
\
FAULT-EPICENTER MAP
SAN DIEGO COUNTY REGION
Indicated Earthquake Events Through A 200 Year Period
EPICENTER MAP LEGEND
I
Ii -;;
¥; ;}. -=
8('0 · 1~Q -~w-a 1!::-'.il
_. ; 'J -6! .i!:1 • F "': F. 4 • ~; ~ :: •
H,·. "'Ir.,;,,-:. ~.1111· 1Q
1-f _.1\\·.1,•:, •'·'-·· .11:
-• • • •
-• • • •
---------
Map is reproduced from California Division of Mines and
Geology, "Epicenters of/ and Areas Damaged by M ~ 5
California Earthquakes, 1800-1999".
FIGURE 8
SMS Geotechnical Solutions, Inc.
5931 Sea Lion place, Suite 109
Carlsbad, CA 92010
Project
Supervising Lab Tech
Supervising Lab Manager
100
90
80
70
l:lO 60 C
V)
V) ro
Cl.. .._. 50
C Q) u .... 40 Q)
Cl..
30
20
10
0
500 100
Carefree Holdings, LLC
S.8.
S.M.S.
~ 00
------M M
"'
Sieve Analysis
ASTM D 6913 -04
0 ..-i
=1:1:
Job#
Address
Date
0 N
=1:1:
so 10 5 1
Grain Size (mm)
9/28/2017
I I I I II
i I I : I : I : ' :
I I
0.5
Gl-17-09-139
2465 Jefferson St., Carlsbad
0 0 ..-i
'#
Tech
0 0 N
=1:1:
....
0.1 0.05
F.A.
....
.... .....
0.01
Cobbles Gravel Sand
Coarse I Fine Coarse I Medium I Fine
Silt or Clay
TP@2.5' 8-1@ 10'
D60 0.28 D60 0.5 D60 D60
D30 0.14 D30 0.25 D30 D30
D10 0.016 D10 0.15 D10 D10
Location Depth Symbol uses NAT,w% LL PL Pl Cu (D60/D10) Cc (D230/ D60*D10)
TP-1 2.5' -SP/SM 7 17.50 4.38
8-1 10' 0 SP/SW 3 3.33 0.83
Figure# 9
(a) (b)
ISOLATION JOINTS
CONTRACTION JOINTS
NOTES:
RE-ENTRANT CORNER
REINFORCEMENT
NO. 3 BARS PLACED
MID-HEIGHT IN SLAB
(c)
I NO SCALE I
RE-ENTRANT
CORNER CRACK
1. Isolation joints around the columns should be either circular as shown in (a) or diamond shaped as shown in (b).
if no isolation joints ore used around columns, or if the corners of the isolation joints do not meet the contraction
joints, radial cracking as shown in (c) may occur (reference ACI).
2 . In order to control crocking of the re-entont corners ( + /-270 degree corners), provide reinforcement as shown in
(c).
3. Re-entrant corner reinforcement shown herein is herein is provided as o general guideline only and is subject to
verification and changes by the project architect and /or structural engineer based upon slab geometry, location,
and other engineering and construction factors.
6116 GEOTECHNICAL SOLUTIONS. INC.
Consulting Geotechnical Engineers & Geologists
5931 Sea Lion Place, Suite 109
Carlsbad, California 92010
760-602-7815
smsgeosoLinc@gmail.com
lifftl~Al i~O~VION JO[Nf§ ~Ni)
i~0 ~NTetAN'f ~ORN~~
~~[NfORC~M~NV
PIOJEC'f WO: FIGURI N~:
Gl-17-09-139 10
5o -
40 -
3o -'
2o
10
TYPICAL SWIMMING POOL CONSTRUCTION CONCEPT
SCHEMATIC ONLY -NOT FOR CONSTRUCTION
SCALE: 1' = 10'
Toporslo~
( T':f P',)
7o
I • 12 min. so
40
-20
10
FIGURE 12
DRILL 5/8" DIA. X 6" DEEP HOLES
@ 18" C.C., THOROUGHLY
CLEAN, DOWEL W/#4 BARS AND
EPOXY GROUT
I
1_11_1j l
MOISTURE BARRI
MID-HEIGHT IN S
EXISTING/NEW WALL·
FOOTING (TYP)
EXISTING SLAB (TYP)
2-#4 BARS TOP AND·
NOTES:
BOTTOM
UNDISTURBED SOIL OR ·
COMPACTED FILL PER
GEOTECHNICAL ENGINEER
(SEE REPORT}
1'-6" (MIN)
I NO SCALE I
EXTERIOR WALL (TYP.)
2 CLR (MIN.)
I
ROUGHEN EXISTING CONCRETE,
CLEAN AND APPLY EPOXY BEFORE
POURING NEW CONCRETE.
RADE ~--
-,--I
#4 CONTINUOUS
#4116" DOWELS@18" C.C
#3 TIES @ 18" C.C.
1. THIS DETAIL IS PROVIDED AS A GENERAL GUIDELINE AND IS NOT FOR CONSTRUCTION.
2. DETAILED GRADE BEAM DESIGN FOR UNDERPINNING SHOULD BE PROVIDED BY THE PROJECT STRUCTURAL
ENGINEER.
3. ALL GRADE BEAM DETAILS AND DIMENSIONS SHOULD BE CONFIRMED AND CERTIFIED BY THE PROJECT
STRUCTURAL ENGINEER PRIOR TO CONSTRUCTION.
§H§ GEOTECHNICAL SOLUTIONS, INC.
5931 Sea Lion Place, Suite 109
Ca rlsbad, California 92010
760-602-7815
smsgeosol.inc@gmail.com
TYPICAL GRADE BEAM DETAIL FOR
UNDERPINNING WALL FOOTINGS
PROJECT NAME: FIGURE NO:
Gl -17-09-139 11
SPECIFICATIONS FOR CALTRANS
CLASS 2 PERMEABLE MATERIAL
(68-1.025)
U.S. STANDARD
SIEVE SIZE
l"
3/4
3/8
No. 4
No. 8
No. 30
No. 50
No. 200
% PASSING
100
90-100
40-100
25-40
18-33
5-15
0-7
0-3
SAND EQUIVALENT> 75
RETAINING WALL ---
FILTER /\1\ATERIAL, 3/4" -11" CRUSHED
ROCKS (WRAPPED IN FILTER FABRIC
OR CAlTRANS CLASS 2 PERMEABLE
/\1\ATERIALS (SEE SPECIFICATIONS)
WATERPROOFING (TYP)
FINISH GRADE
6"MIN.
CONCRETE-LINED DRAINAGE DITCH
FILTER MATERIAL, 3/4" • lf' CRUSHED
ROCKS (WRAPPED IN FILTER FABRIC OR
CAL TRANS CLASS 2 PERMEABLE
MATERIALS (SEE SPECIFICATIONS)
WATERPROOFING [TYP)
PROPOSED GRADE
6"MIN.
CONSTRUCTION SPECIFICATIONS:
I NO SCALE I
I NO SCALE I
GROUND SURFACE
MIN. 90% COMPACTED FILL
(TYP)
APPROVED FILTER FABRIC (MIRAFI
i:o'" 140N) 12" OVERLAP, TYP. z~ ~o
= z
CX) w ~w
~
4' PVC PERFORATED PIPE MIN.
(SCH 40 OR SDR35) MIN. 1 /2%
FALL TO APPROVED OUTLET
(SEE REPORT)
NATURAL OR GRADED SLOPE
TEMPORARY
1 : 1 CUT SLOPE
PROPERLY COMPACTED (MIN. 90%) BACKFILLED
GROUND
----BENCH AND TIGHTLY KEY INTO TEMPORARY
BACKCUT AS BACKFILLING PROGRESSES
APPROVED FILTER FABRIC (MIRAFI 140N) 12'
OVERLAP, TYP.
------4' PVC PERFORATED PIPE MIN. (SCH 40 OR SDR35)
MIN. 1 /2% FALL TO APPROVED OUTLET (SEE
REPORT)
l. Provide granular, non-expansive backfill soil in l : l gradient wedge behind wall. compact backfill to minimum 90% of
laboratory standard.
2. Backdrain should consist of 4" diam1;ter PVC pipe (Schedule 40 or equivalent) with perforations down. Drain to suitable
at minimum!%. Provide 3/4" -l ~" c(ushed rocks filter materials wrapped in fabric (Mirofi 140N or equivalent). Delete
filter fabric wrap if Coltrans Closs 2 permeable material is used. Compact Class 2 permeable material to minimum 90%
of laboratory standard.
3. Seal back of wall with approved waterproofing in accordance with architect's specifications.
4. Provide positive drainage to disallow ponding of water above wall. Drainage to flow away from wall at minimum 2%.
Provide concrete-lined drainage ditch for slope toe retaining walls.
5. Use 1 ~ cubic feet per foot with granular backfill soil and 4 cubic foot per foot if expansive backfill is used.
8.116 GEOTECHNICAL SOLUTIONS, INC.
Consulting Geotechnical Engineers & Geologists
5931 Sea Lion Place, Suite 109
Carlsbad, California 920 I 0
760-602-7815
smsgeosol.inc@gmail.com
TYPI CAL RETAINING WALL BACK
DRAINAGE
PROJECT NO: FIGURE NO:
Gl-17-09-139 13
APPENDIX
Design Maps Summary Report
r.lUSGS Design Maps Summary Report
User-Specified Input
Report Title Mr. Christopher Sauer, 2465 Jefferson St., Carlsbad
Jue September· 5, 20111/:05:1/ LJIC
Building Code Reference Document ASCE 7-10 Standard
(wt,ich utilizes LJSGS hazard data available in 2008)
Site Coordinates 33.1697°N, 117.3488°W
Site Soil Classification Site Class D -"Stiff Soil"
Risk Category I/II/III
1¥111..l 1•our.ritw
Oceansidl
Carlsba'·
:rs
-Vista
S~n Marcos
_I
Escondido'
USGS-Provided Output
Ss = 1.145 g
s, = 0.439 g
SMs = 1.193 g
SM1 = 0.685 g
Sos= 0.795 g
So1 = 0.457 g
Page 1 of 2
For information on how the SS and 51 values above have been calculated from probabilistic (risk-targeted) and
deterministic ground motions in the direction of maximum horizontal response, please return to the application and
select the "2009 NEHRP" building code reference document.
J .:.
~ :i ._
~ J((
For PGAM, T,, c.s, and c., values, please view the detailed report.
https://earthquake. usgs.gov /cn2/designmaps/us/summary. php?template=minimal&latitude=... 9/5/2017
Design Maps Detailed Report
lilJSGS Design Maps Detailed Report
ASCE 7-10 Standard (33.1697°N, 117.3488°W)
Site Class D -"Stiff Soil", Risk Category I/II/III
Section 11.4.1 -Mapped Acceleration Parameters
Page 1 of 6
Note: Ground motion values provided below are for the direction of maximum horizontal
spectral response acceleration. They have been converted from corresponding geometric
mean ground motions computed by the USGS by applying factors of 1.1 (to obtain Ss) and
1.3 (to obtain S,). Maps in the 2010 ASCE-7 Standard are provided for Site Class B.
Adjustments for other Site Classes are made, as needed, in Section 11.4.3.
From Figure 22-1 111 Ss=l.145g
From Figure 22-2 121 s, = 0.439 g
Section 11.4. 2 -Site Class
The authority having jurisdiction (not the USGS), site-specific geotechnical data, and/or
the default has classified the site as Site Class D, based on the site soil properties in
accordance with Chapter 20.
Ta ble 20.3-1 Site Classification
Site Class
A. Hard Rock
B. Rock
C. Very dense soil and soft rock
D. Stiff Soil
E. Solt clay soil
F. Soils requiring site response
analysis in accordance with Section
21.1
Vs Nor Nch Su
>5,000 ft/s N/A N/A
2,500 to 5,000 ft/s N/A N/A
1,200 to 2,500 ft/s· >SO >2,000 psf
600 to 1,200 lt/s 15 to SO 1,000 to 2,000 psf
<600 lt/s <15 <1,000 psf
Any profile with more than 10 It of soil having the characteristics:
• Plasticity index PI > 20,
• Moisture content w 2:: 40%, and
• Undrained shear strength Su < 500 psf
--------
See Section 20.3.1
For SI: 1~/s = 0.3048 m/s llb/ft2 = 0.0479 kN/m2
https://earthquake.usgs.gov/cn2/designmaps/us/report.php?template=minimal&latitude=33.... 9/5/2017
Design Maps Detailed Report Page 2 of 6
Section 11.4.3 -Site Coefficients and Risk-Targeted Maximum Considered Earthquake
(MCER) Spectral Response Acceleration Parameters
Table 11.4-1: Site Coefficient F.
Site Class Mapped MCE • Spectral Response Acceleration Parameter at Short Period
Ss $ 0.25 Ss = 0.50 Ss = 0 .75 Ss = 1.00 Ss ~ 1.25
A 0.8 0 .8 0.8 0.8 0.8
B 1.0 1.0 1.0 1.0 1.0
C 1.2 1.2 1.1 1.0 1.0
D 1.6 1.4 1.2 1.1 1.0
E 2.5 1.7 1.2 0.9 0.9
F See Section 11.4.7 of ASCE 7
Note: Use straight-line interpolation for intermediate values of Ss
For Site Class = D and Ss = 1.145 g, F. = 1.042
Table 11.4-2: Site Coefficient F.
Site Class Mapped MCE • Spectral Response Acceleration Parameter at 1-s Period
S1 $ 0.10 S1 = 0.20 S1 = 0.30 S1 = 0.40 s, ~ 0.50
A 0.8 0.8 0.8 0.8 0.8
B 1.0 1.0 1.0 1.0 1.0
C 1.7 1.6 1.5 1.4 1.3
D 2.4 2.0 1.8 1.6 1.5
E 3.5 3.2 2.8 2.4 2.4
F See Section 11.4. 7 of ASCE 7
Note: Use straight-line interpolation for intermediate values of S1
For Site Class = D and S1 = 0.439 g, F. = 1.561
https://earthquake.usgs.gov/cn2/designmaps/us/report.php?template=minimal&latitude=33.... 9/5/2017
Design Maps Detailed Report
Equation (11.4-1): SMs = F.Ss = 1.042 X 1.145 = 1.193 g
Equation (11.4-2): SMl = fvS1 = 1.561 X 0.439 = 0,685 g
Section 11.4.4 -Design Spectral Acceleration Parameters
Equation (11.4-3): Sos =½ SMs = ½ X 1.193 = 0.795 g
-------------------------
Equation (11.4-4): Soi =½SM! = ½ X 0.685 = 0.457 g
Section 11.4.5 -Design Response Spectrum
From Figure 22-12 131 TL = 8 seconds
Figure 11.4-1: Design Response Spectrum
T < T0 : S0 = S011 ( 0.-4 + 0.6 T /T0 )
T0 STST9 :S,=S05
T6 <TS TL: S1 = S0,JT
T>TL:S,=S0,TL/Tl
Su, ~0-457 _..._ ___ -------, ______ ----
' I I
io-0.115 1.00:)
Pe,,oa. T (,~)
Page 3 of 6
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Section 11.4.6 -Risk-Targeted Maximum Considered Earthquake (MCER) Response
Spectrum
The MCE, Response Spectrum is determined by multiplying the design response spectrum above by
1.5.
S,,, ~ 1.19 3 --...-------.
s,,. ~ 0.685 -1-----------0 ----------
I I
I I
I I
7,.~0.115
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Section 11.8.3 -Additional Geotechnical Investigation Report Requirements for Seismic
Design Categories D through F
From Figure 22-7 141 PGA = 0.452
Equation {11.8-1): PGAM = FPGAPGA = 1.048 x 0.452 = 0.474 g
Table 11.8-1: Site Coefficient FPGA
Site Mapped MCE Geometric Mean Peak Ground Acceleration, PGA
Class
PGA s PGA = PGA = PGA = PGA ~
0.10 0.20 0.30 0.40 0.50
A 0.8 0.8 0.8 0.8 0.8
B 1.0 1.0 1.0 1.0 1.0
C 1.2 1.2 1.1 1.0 1.0
D 1.6 1.4 1.2 1.1 1.0
E 2.5 1. 7 1.2 0.9 0.9
F See Section 11.4. 7 of ASCE 7
Note: Use straight-line interpolation for intermediate values of PGA
For Site Class = D and PGA = 0.452 g, F•oA = 1.048
Section 21.2.1.1 -Method 1 (from Chapter 21 -Site-Specific Ground Motion Procedures
for Seismic Design)
From Figure 22-17151 CRs = 0.946
From Figure 22-18 161 CR, = 0. 997
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Section 11.6 -Seismic Design Category
Table 11.6-1 Seismic Design Category Based on Short Period Response Acceleration Parameter
RISK CATEGORY
VALUE OF Sos
I or II III IV
Sos< 0.167g A A A
0.167g S Sos< 0.33g B B C
0.33g S Sos < O.SOg C C D
O.SOg S Sos D D D
For Risk Category = I and Sos = 0. 795 g, Seismic Design Category = D
Table 11 6-2 Seismic Design Category Based on 1-5 Period Response Acceleration Parameter
RISK CATEGORY
VALUE OF So,
I or II III IV
So,< 0.067g A A A
0.067g S So, < 0.133g B B C
0.133g s 501. < 0.20g C C D
0.20g S So1 D D D
For Risk Category = I and S01 = 0.457 g, Seismic Design Category = D
Note: When S1 is greater than or equal t o 0. 75g, the Seismic Design Category is E for
bu ildings in Risk Categories I, II, and III, and F for those in Risk Category IV, irrespective
of the above.
Seismic Design Category = "the more severe design category in accordance with
Table 11.6-1 or 11.6-2" = D
Note : See Section 11.6 for alternative approaches to calculating Seismic Design Category.
References
1. Figure 22-1 :
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https://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7 _Figure_22-1. pdf
2. Figure 22-2:
https ;//earthquake. usgs.gov /hazards/desig nmaps/downloads/pdfs/201 O_ASCE-7 _Figure_22-2. pdf
3. Figure 22-12:
https ://earthquake. usgs.gov /hazards/designmaps/downloads/pdfs/201 O_ASCE-7 _Figu re_22-12. pdf
4. Figure 22-7:
https ://earthquake. usgs.gov /haza rds/desig nmaps/ downloads/pdfs/201 O_ASCE-7 _Figure_22-7. pdf
5. Figure 22-17:
https ://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7 _Figure_22-17 .pdf
6 . Figure 22-18 :
https ://earthquake. usgs.gov /hazards/desig nma ps/downloads/pdfs/201 O_ASCE-7 _Figure_22-18. pdf
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