HomeMy WebLinkAboutPUD 14-04; SPRAGUE LOT SPLIT; GEOTECHNICAL UPDATE EVALUATION; 2014-04-22ClTY Cr CARLSB/\-")
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GEOTECHNICAL UPDATE EVALUATION
PROPOSED FOUR-LOT SUBOIVISION
8480 LA MESA BOULEVARD
LA MESA, CALIFORNIA 91942
W.O. 6653-A-SC REVISED APRIL 22, 2014
I
Geotechnical • Geologic • Coastal • Environmental
5741 PalmerWay • Carlsbacl, California 92010 • (760) 438-3155 • FAX (760) 931-0915 • www.geosoilsinc.com
Revlse<d April 22, 2014
W.O. 6653-A-SC
The Kevane Company, Inc.
8480 La Mesa Boulevard
La Mesa, California 91942
Attention: Mr. Bob Kevane
Subject: Geotechnical Update Evaluation, Proposed Four-Lot Subdivision, Lot "J" of
Rancho Agua Hedionda, APNs 167-230-24 and -25, Carlsbad, San Diego
County, California
Dear Mr. Kevane:
In accordance with your request and authorization, GeoSoils, Inc. (GSI) is presenting the
results of our geotechnical update evaluation ofthe subject site. The purpose ofthis study
was to provide updated geotechnical conclusions and recommendations relative to the
proposed four-lot residential subdivision at the subject site in light of the existing
geotechnical data; the currently planned El Camino Real widening project that will occur
along the westerly margin ofthe subject site; the proposed residential development shown
on the "Conceptual Lot Split Design, prepared by Walsh Engineering and Surveying, Inc.
(WE&S [2014], and current building code requirements. Unless specifically superceded
herein, the conclusions and recommendations presented in GSI (1989 [see Appendix A])
remain valid and applicable, and should be appropriately implemented during the balance
of project design and construction.
SCOPE OF SERVICES
The scope of our services for this geotechnical update evaluation has included the
following:
1. Review of readily available published literature, aerial photographs, and maps ofthe
vicinity, including previous site-specific studies performed by Ninyo and Moore
(N&M) and this firm (see Appendix A). The summary reports for these studies are
also provided in Appendix A on a CD data disc.
2. Site reconnaissance mapping and the excavation of five (5) exploratory test pits to
further evaluate the soil/bedrock profiles, sample representative earth materials, and
delineate the horizontal and vertical extent of earth material units (see Appendix B).
3. Updated general areal seismicity evaluations (see Appendix C).
4. Appropriate laboratory testing of relatively undisturbed and representative bulk soil
samples collected during our recent geologic mapping and subsurface exploration
program (see Appendix D).
5. Analysis of field and laboratory data relative to the proposed development, including
slope stability (see Appendix E).
6. Appropriate engineering and geologic analyses of data collected, and the
preparation ofthis summary report and accompaniments.
PROPOSED DEVELOPMENT
Based on our review ofthe "Conceptual Lot Split Design" plan prepared by WE&S (2014)
and communication with representatives of WE&S, GSI understands that the subject site
will be subdivided into four (4) residential lots with an associated private roadway,
underground utilities, and ancillary lot improvements (walls, walkways, patios, etc.). We
further understand that site development will incorporate permanent IVa:!
(horizontahvertical [h:v]) graded slopes, which are a part ofthe City of Carlsbad's planned
widening ofthe adjacent El Camino Real. GSI points out that there are differences in the
configuration and widths of the private roadway shown on WE&S (2014) and the City of
Carlsbad grading plans for the El Camino Real widening project, prepared by Bureau
Veritas (undated). These discrepancies should be brought to the attention ofthe City of
Carlsbad Engineer so that they are either incorporated into the El Camino Real widening
projectortheCity of Carlsbad is aware that the proposed residential development will alter
the final design grades shown on Bureau Veritas (undated).
Bureau Veritas (undated) indicates that maximum planned cuts and fills during the planned
El Camino Real widening will be on the order of 22 feet and 11 feet, respectively. Bureau
Veritas (undated) also depicts planned iy2:1 (h:v) cut and fill-over-cut slopes with
maximum overall heights on the order of 48 feet and 50 feet, respectively. Where the
planned residential development is shown on WE&S (2014), maximum cuts and fills are
on the order of 14 feet and 3 feet, respectively. WE&S (2014) also shows a planned cut
slope with a maximum height of approximately 17 feet.
PREVIOUS WORK
GSI performed a preliminary geotechnical evaluation for previous site design concepts in
1989 (GSI, 1989). Based on the body of work performed in conjunction with this
investigation, GSI concluded that the then-proposed development concept was feasible
from a geotechnical standpoint. GSI indicated that the most significant geotechnical issues
relative to developing this site included: 1) potentially compressible soils ranging up to
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20 feet in thickness; 2) the presence of low to critically expansive soils; 3) the potential for
the site to experience ground shaking from a nearby earthquake; 4) the susceptibility of
the west-facing cut slope to mass wasting events; and 5) the possible need for extensive
import fill materials since the existing dumped fill material contained abundant deleterious
debris.
In 2009, Ninyo and Moore (N&M) investigated the site for the City of Carlsbad for
preliminary design work related to the widening of El Camino Real (N&M). Based on their
studies, N&M concluded that the most significant geotechnical factors related to the
El Camino Real widening within the subject site included: 1) the proposed cut slope
exposing adverse bedding within the Santiago Formation; 2) erosion on the planned
1 Va:! (h:v) cut slope from limitations of establishing sufficient vegetation, owing to dense
sandstone exposures; 3) remedial earthwork necessary to treat dumped existing fill
materials; 4) potentially encountered strongly cemented zones within the
Santiago Formation and very old paralic deposits, possibly requiring the use of heavy
ripping or rock breakers; 5) possibly encountered perched water seepage along geologic
contacts during construction; 6) the unsuitability ofthe existing dumped fill materials for
reuse in engineered fills due to abundant deleterious debris; 7) marginal surficial stability
of the planned IVa:! (h:v) slopes; and 8) the potential for the site to experience strong
ground shaking from a nearby earthquake. In order to increase the marginal
Factor-of-Safety (FOS) against surficial stability, N&M recommended that the proposed
172:1 (h:v) cut slopes indicated on Bureau Veritas (undated) be overexcavated and
reconstructed as fill slopes with geogrid reinforcement in the outer 8 feet of the slope.
SITE GEOLOGY
Observations during our recent field study indicated that the site geologic conditions were
generally consistent with those reported in GSI (1989). However, a thin layer of
undifferentiated undocumented fill and talus debris now mantles the lower portions ofthe
west-facing slope, near the northerly end ofthe property. This earth material was likely
produced during the mitigation of the overhanging portions of this slope that occurred a
few years ago. These materials generally consist of a brown, light gray, and reddish yellow
clayey sand with abundant subrounded and rounded pebble- to cobble-sized clasts. The
mudstone bed within Santiago Formation that was identified in our 1989 study was
observed near the bend in the entrance driveway between approximate elevations of 260
and 262 feet. This bed was also observed in the Santiago Formation exposure south of
the entrance driveway between similar elevations. This bed does not appear to be
continuous throughout the site and has likely been truncated by ancient erosional
processes or removed by previous grading activity. It should be noted that regional
nomenclature forthe Quaternary Lindavista Formation has been amended to Quaternary
very old paralic deposits (Kennedy and Tan, 2005). This change has no bearing on the
fundamental conclusions and recommendations contained in GSI (1989) nor this study.
The general site geologic conditions are shown on Plate 1 (Geotechnical Map) and
Plates 2 and 3 (Geologic Cross Sections A-A' and B-B).
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UPDATED GEOLOGIC AND SEISMIC HAZARD ASSESSMENT
General
According to the City of Carlsbad Geotechnical Hazard Analysis and Mapping Study (David
Evans and Associates, Inc. and Leighton and Associates, Inc, 1992), the subject site falls
with Hazard Categories 25 and 51. Hazard Category 25 is defined as areas of relatively
level or sloping terrain underlain by thick claystone or siltstone; other slide prone soils.
Hazard Category 51 is defined as areas of moderately sloping terrain underlain by terrace
deposits or sandstone. Both Hazard Categories are considered to present marginal to
moderate risks to development. Geologic hazards and the potential of each to affect the
proposed development are further discussed in the following sections.
Mass Wasting/Landslide Susceptibility
Mass wasting refers to the various processes by which earth materials are moved down
slope in response to the force of gravity. Examples of these processes include slope
creep, surficial failures, and deep-seated landslides. Creep is the slowest form of mass
wasting and generally involves the outer 5 to 10 feet of a slope surface. During heavy
rains, such as those in El Nino years, creep-affected materials may become saturated,
resulting in a more rapid form of downslope movement (i.e., landslides and/or surficial
failures).
According to regional landslide susceptibility mapping by Tan (1995), the site is located
within landslide susceptibility Subarea 3-1 which is characterized as being "generally
susceptible" to landsliding. Further, David Evans and Associates, Inc. and Leighton and
Associates, Inc. (1992) indicate that slide-prone soils exist near the southerty margin ofthe
property.
Based on our recent and past observations, the steep cut slope that descends to
El Camino Real is undergoing rapid erosion. The previous overhanging ledges that once
existed near the geologic contact between the more resistant very old paralic deposits and
the underlying, less resistant Santiago Formation are a testament to the rapid erosion
occurring along this slope. Priorto mitigation, the overhanging portions ofthe slope were
susceptible to toppling failures. The trimming of the overhanging slope areas has
temporarily mitigated the potential for widespread toppling failures to occur. However,
without permanent mitigation, heterogenous erosion rates between the very old paralic
deposits and the Santiago Formation will likely reform overhanging ledges and subject the
slope to toppling failures once again. The presence of out-of-slope dipping beds and the
relatively weak mudstone bed within the Santiago Formation are also considered adverse
with respect to the stability ofthis slope in its current state.
Planned site development includes modifications to the existing slope configuration. As
such, GSI analyzed the stability of the slope's planned graded configuration to evaluate
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ifthe proposed residential development has code-compliant factors-of-safety. The results
of our slope stability analyses are presented herein.
UPDATED FAULTING AND REGIONAL SEISMICITY EVALUATION
Regional Faults
Our review indicates that there are no known active faults crossing the project and the site
is not within an Alquist-Priolo Earthquake Fault Zone (Bryant and Hart, 2007). However,
the site is situated in a region subject to periodic earthquakes along active faults.
The Rose Canyon fault is the closest known active fault to the site (located at a distance
of approximately 6.5 miles [10.5 kilometers]) and should have the greatest effect on the
site in the form of strong ground shaking, should the design earthquake occur. However,
as indicated in GSI (1989), the recurrence interval for the Rose Canyon fault is relatively
low, and it is likely that the site could experience strong ground shaking from earthquakes,
occurring along the San Jacinto fault or the southern segment of the San Andreas fault
which have higher rates of recurrence. The locations ofthe Rose Canyon, San Jacinto,
and San Andreas faults and other major faults, relative to the site, are shown on the
"California Fault Map" in Appendix C. The possibility of ground acceleration, or shaking
at the site, may be considered as approximately similar to the southern California region
as a whole.
Local Faulting
No faults were observed to specifically transect the site during the field investigation
performed in preparation of GSI (1989) nor for this study. Additionally, a review of available
regional geologic maps does not indicate the presence of faults crossing the specific
project site. Weber (1982) does, however, indicate a short fault splay that parallels
El Camino Real near its intersection with Chestnut Avenue. This fault splay was mentioned
in GSI (1989), but was not observed within the subject site.
Surface Fault Rupture
Given the lack of evidence suggesting the presence of onsite faults, the potential for
surface fault rupture to effect the proposed development is considered very low.
Seismicity
Maximum Credible Site Acceleration
The acceleration-attenuation relation of Bozorgnia, Campbell, and Niazi (1999) has been
incorporated into EQFAULT (Blake, 2000a). EQFAULT is a computer program developed
by Thomas F. Blake (2000a), which performs deterministic seismic hazard analyses using
digitized California faults as earthquake sources.
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The program estimates the closest distance between each fault and a given site. If a fault
is found to be within a user-selected radius, the program estimates peak horizontal ground
acceleration that may occur at the site from an upper bound (formerly "maximum credible
earthquake"), on that fault. Upper bound refers to the maximum expected ground
acceleration produced from a given fault. Site acceleration (g) was computed by
one user-selected acceleration-attenuation relation that is contained in EQFAULT. Based
on the EQFAULT program^ a peak horizontal ground acceleration from an upper bound
event on the Rose Canyon fault may be on the order of 0.54 g. The computer printouts of
pertinent portions ofthe EQFAULT program are included within Appendix C.
Historical Site Acceleration
Historical site seismicity was evaluated with the acceleration-attenuation relationship of
Bozorgnia, Campbell, and Niazi (1999), and the computer program EQSEARCH
(Blake, 2000b, updated to July 2013). This program performs a search ofthe historical
earthquake records for magnitude 5.0 to 9.0 seismic events within a 100-kilometer radius,
between the years 1800 through July 2013. Based on the selected
acceleration-attenuation relationship, a peak horizontal ground acceleration is estimated,
which may have affected the site during the specific event listed. Based on the available
data and the attenuation relationship used, the estimated maximum (peak) site
acceleration during the penod 1800 through July 2013 was about 0.24 g. A historic
earthquake epicenter map and a seismic recurrence curve are also estimated/generated
from the historical data. Computer printouts ofthe EQSEARCH program are presented in
Appendix B.
SEISMIC DESIGN PARAMETERS
Based on the site conditions, the following table summarizes the site-specific design
criteria obtained from the 2013 California Building Code ([2013 CBC], California Building
Standards Commission [CBSC], 2013), Chapter 16 Structural Design, Section 1613,
Earthquake Loads. The computer program "U.S. Seismic Design Maps, provided bythe
United States Geological Survey (http://geohazards.usgs.gov/designmaps/
us/application.php) was utilized for design. The short spectral response utilizes a period
of 0.2 seconds.
2013 CBC SEISMIC DESIGN PARAMETERS
^ PARAMETER VALUE 2013 CBC AND/OR REFERENCE
Risk Category II Table 1604.5
Site Class C Section 1613.3.2/ASCE 7-10
(Chapter 20)
Spectral Response - (0.2 sec), 1.104 g Figure 1613.3.1(1)
Spectral Response - (1 sec), S, 0.425 g Figure 1613.3.1(2)
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201^.CBC SEISMIC DESIGN PARAMETERS 1*^,.
' 'PARAM'^TER ^ VALUE 2013'^BC ^D/OFT REFERE^I'CE
Site Coefficient, F, 1.0 Table 1613.3.3(1)
Site Coefficient, F„ 1.375 Tablel 613.3.3(2)
Maximum Considered Earthquat<e Spectral
Response Acceleration (0.2 sec), S^g 1.104 g Section 1613.3.3
(Eqn 16-37)
Maximum Considered Earthqual<e Spectral
Response Acceleration (1 sec), S„, 0.584 g Section 1613.3.3
(Eqn 16-38)
5% Damped Design Spectral Response
Acceleration (0.2 sec), S^s 0.736 g Section 1613.3.4
(Eqn 16-39)
5% Damped Design Spectral Response
Acceleration (1 sec), 0.390 g Section 1613.3.4
(Eqn 16-40)
Seismic Design Category D Section 1613.3.5/ASCE 7-10
(Table 11.6-1 or 11.6-2)
PGA, 0.430 g ASCE 7-10 (Eqn 11.8.1)
GENERAL SEISMIC DESIGN I>A'RAMETERS
PARAMETER VALUE
Distance to Seismic Source'^' - B fault'^' (Rose Canyon fault) 6.5 mi/10.5 km
Upper Bound Earthquake (Rose Canyon fault) Mw= 7.2'^>
- From Blake (2000a)
- Cao, et al. (2003)
Conformance to the criteria above for seismic design does not constitute any kind of
guarantee or assurance that significant structural damage or ground failure will not occur
in the event of a large earthquake. The primary goal of seismic design is to protect life, not
to eliminate all damage, since such design may be economically prohibitive. Cumulative
effects of seismic events are not addressed in the 2013 CBC (CBSC, 2013) and regular
maintenance and repair following locally significant seismic events (i.e., M„5.5) will likely
be necessary.
It is important to keep in perspective that in the event of a major earthquake occurring on
any of the nearby major faults, strong ground shaking would occur in the subject site's
general area. Potential damage to any structure(s) would likely be greatest from the
vibrations and impelling force caused by the inertia of a structure's mass than from those
induced by the hazards considered above. Following implementation ofthe foundation
design and construction recommendations, described herein, this potential would be no
greater than that for other existing structures and improvements in the immediate vicinity
that comply with current and adopted building standards.
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UQUEFACTION AND SEISMIC DENSIFICATION POTENTIAL
Liguefaction
Liquefaction descnbes a phenomenon in which cyclic stresses, produced by
earthquake-induced ground motion, create excess pore pressures in relatively
cohesionless soils. These soils may thereby acquire a high degree of mobility, which can
lead to vertical deformation, lateral movement, lurching, sliding, and as a result of seismic
loading, volumetric strain and manifestation in surface settlement of loose sediments, sand
boils and other damaging lateral deformations. This phenomenon occurs only belowthe
watertable, but after liquefaction has developed, it can propagate upward into overlying
non-saturated soil as excess pore water dissipates.
One ofthe primary factors controlling the potential for liquefaction is depth to groundwater.
Typically, liquefaction has a relatively low potential at depths greater than 50 feet and is
unlikely and/or will produce vertical strains well below 1 percent for depths below 60 feet
when relative densities are 40 to 60 percent and effective overburden pressures are two
or more atmospheres (i.e., 4,232 psf [Seed, 2005]).
The condition of liquefaction has two principal effects. One is the consolidation of loose
sediments with resultant settlement of the ground surface. The other effect is lateral
sliding. Significant permanent lateral movement generally occurs only when there is
significant differential loading, such as fill or natural ground slopes within susceptible
materials. No such loading conditions exist at the site.
Liquefaction susceptibility is related to numerous factors and the following five conditions
should be concurrently present for liquefaction to occur: 1) sediments must be relatively
young in age and not have developed a large amount of cementation; 2) sediments must
generally consist of medium- to fine-grained, relatively cohesionless sands; 3) the
sediments must have low relative density; 4) free groundwater must be present in the
sediment; and 5) the site must experience a seismic event of a sufficient duration and
magnitude, to induce straining of soil particles. Only one or two of these necessary
concurrent conditions have the potential to affect the site. Therefore, the potential for this
seismic-induced phenomenon is considered low.
Seismic Densification
Seismic densification is a phenomenon that typically occurs in low relative density granular
soils (i.e.. United States Soil Classification System [USCS] soil types SP, SM, and SC) that
are above the groundwater table. These unsaturated granular soils are susceptible if left
in the original density (unmitigated), and are generally dry ofthe optimum moisture content
(as defined by the ASTM D1557). During seismic-induced ground shaking, these natural
or artificial soils deform under loading and volumetrically strain, potentially resulting in
ground surface settlements. Our evaluation assumed thatthe current offsite conditions will
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not be significantly modified by future grading at the time of the design earthquake, which
is a reasonably conservative assumption.
Summarv
It is the opinion of GSI that the susceptibility of the site to experience damaging
deformations from seismically-induced liquefaction and densification is relatively low owing
to the dense nature of the formational earth matenals that underlie the site in the
near-surface and the depth to the regional watertable. In addition, the recommendations
for remedial earthwork and foundations would further reduce any significant
liquefaction/densification at the site. Some low magnitude seismic densification of the
engineered fill (if granular and low expansive) or adjoining un-mitigated site(s), and any
unmitigated onsite soils could occur. GSI estimates this seismic-induced vertical
deformation to be low magnitude and on the order of Vi-inch to 1 inch. However, given
thefoundation recommendations provided herein, the potential forthe planned residential
buildings to be affected by significant seismic densification or liquefaction of offsite soils
may be considered low. This does not preclude deformations induced by lateral
movement of the engineered slopes during the design seismic event.
Other Geologic/Secondary Seismic Hazards
The following list includes other geologic/seismic related hazards that have been
considered during our evaluation ofthe site. The hazards listed are considered negligible
and/or mitigated as a result of site location, soil characteristics, and typical site
development procedures:
Subsidence
Surface Fault Rupture
Ground Lurching or Shallow Ground Rupture
Tsunami
Seiche
RECENT LABORATORY TESTING
General
Laboratory tests were performed on representative samples ofthe onsite earth materials
collected from our recent field exploration in orderto evaluate their physical characteristics.
The test procedures used and results obtained are presented below.
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Classification
Soils were classified visually according to the Unified Soils Classification System (Sowers
and Sowers, 1979). The soil classifications are shown on the Test Pit Logs in Appendix B.
Moisture-Densitv Relations
The field moisture contents and field dry densities of relatively undisturbed soil samples
were evaluated in the laboratory, in general accordance with ASTM D 2216 and ASTM
D 2937. The results of these tests are shown on the Test Pit Logs in Appendix B.
Laboratorv Standard
The maximum density and optimum moisture content was evaluated for a representative
bulk sample ofthe onsite soils. Testing was performed in general accordance with ASTM
D 1557. The moisture-density relationships obtained for these soils are shown on the
following table:
^MAXIMUM
- OE^sfvt (PC'l^)
-OO^TIMUM MOISTURE
'•"*«'C0NTENf (%)
TP-101 @ 0-1 and
TP-104 @ 1V2-2
(Composite Sample)
Grayish Brown Silty Sand
with Asphaltic Concrete 130.0 9.5
Direct Shear Tests
Shear testing was performed on relatively undisturbed and remolded samples of site earth
materials collected from the test pits in general accordance with ASTM D 3080. The shear
testing results are provided in the following table.
ISAMPLE LOCATION
,1 AND DEPTH (FH ^-
PRIMARY' RESIDUAL
ISAMPLE LOCATION
,1 AND DEPTH (FH ^-COHESION
(PSF)
FRICTION ANGLE
([DEGREES)
CJO'HESION
*" (PSR
•FRICTION ANGLE
' (DEGREES)
TP-101 @ 0-1 and
TP-104 @ iy2-2
(Composite Sample Remolded
to 90 Percent of the Laboratory
Standard [ASTM D 1557]))
409 30 176 32
TP-103 @ 1 % 250 27 150 27
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Saturated Resistivitv, pH, and Soluble Sulfates, and Chlorides
GSI conducted sampling of onsite earth materials for general soil corrosivity and soluble
sulfates, and chlorides testing. The testing included evaluation of soil pH, soluble sulfates,
chlorides, and saturated resistivity. Test results are presented in Appendix D and the
following table:
SAMPLE^LpCATION
AND DEPTH (FT) pH
• SATURATED
RESISTIVITY
'(olTni'»cni)
' SOLUBLE
.SULf'iETM
(ppm)
S0.LJUBLE
CHLORIDES
(ppm)
TP-101 @ 0-1 and
TP-104 @ 1^/2-2
(Composite Sample)
6.61 2,250 0.0015 87
Corrosion Summary
Laboratory testing indicates that the tested sample ofthe onsite soils is neutral with respect
to soil acidity/alkalinity, is moderately corrosive to exposed, buried metals when saturated,
presents negligible sulfate exposure ("Exposure Class SO") to concrete, and although not
negligible, is below the action level for chloride exposure (per State of California
Department of Transportation, 2003). It should be noted that GSI does not consult in the
field of corrosion engineering. Therefore, additional comments and recommendations may
be obtained from a qualified corrosion engineer based on the level of corrosion protection
required for the project, as determined by the project architect and/or structural engineer.
Local jurisdiction right-of-way utilities and connections may require a more stringent level
of corrosion protection.
SLOPE STABILITY ANALYSIS
Since the proposed lots will largely be supported by the IVa:! (h:v) cut and fill slopes
recommended by N&M and shown on Bureau Veritas (undated), and since the project
includes additional fill and improvement loading above these slopes, GSI performed
independent slope stability analyses to evaluate the FOS of the finished slope
configuration as well as the 1:1 (h:v) backcuts recommended by N&M. Slope stability
analyses were performed with the aid of the two-dimensional slope stability computer
program "GSTABL7 v.2" developed by Gregory (2003). For a complete discussion on the
GSTABL7 program, please referto Appendix E.
Slope stability analyses were performed along Geologic Cross Sections A-A' and B-B."
These sections were selected forthe analyses because they represent the highest planned
cut and fill-over-cut slope configurations. With the exception ofthe Santiago Formation,
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isotropic soil shear strength values were incorporated for the earth material units.
Anisotropic cross-bed and parallel bed strengths were applied to the Santiago Formation
owning to adversely oriented bedding planes.
The results of the slope stability analyses indicate that for the two areas of the site within
the influence of Geologic Cross Sections A-A' and B-B,' the proposed slopes indicated on
WE&S (2014) generally have adequate factors-of-safety (i.e., 1.5 and 1.1 for static and
seismic conditions, respectively). However, our stability analyses for Geologic Cross
Section A-A' indicated that there is some potential for this slope to have marginal to
inadequate static factors-of-safety within the grid-reinforced zone. That is to say static
factors-of-safety of ±1.5 or less (see Appendix E). This will likely require the use of
longer/stronger grid reinforcement, more closely-spaced gnd reinforcement, higher quality
import fill materials, and/or higher compaction standards. No groundwater was modeled
in any of our analyses. As such, the presence of groundwater at or near the
keyway/backcut would tend to lower the global factor-of-safety. Keyways and backcuts
will be drained and as such, perched water should be removed via subdrain systems.
Import fill should be selected such that the shear strength parameters for engineered fill
(Afe) in the slope stability analyses are met or exceeded. All proposed import fill sources
should be evaluated by GSI and the City of Carlsbad's geotechnical consultant. The use
of select import with low plasticity should be considered.
The cut slope on the northern portion of the site will need to be revisited with respect to
cut/fill contacts, backcut lines (daylight) as they pertain to temporary and global stability
when final lot layouts and grading plans are made available. The estimate of fill soil
strength is based on onsite fills, which if not cleaned of debris and re-used, will be replaced
by a borrow material that has not yet been identified/tested. Therefore, GSI should sample
and evaluate the proposed import fill source for compatibility with the designs and slope
stability assumptions, and analyses reported herein.
PRELIMINARY EMBANKMENT FACTORS (SHRINKAGE/BULKING)
The volume change of excavated materials upon compaction as engineered fill is
anticipated to vary with material type and location. The overall earthwork shrinkage and
bulking may be approximated by using the following parameters:
Undocumented Artificial Fill/Talus 10% to 15% shrinkage
Quaternary colluvium 10% to 15% shrinkage
Very Old Paralic Deposits. 0% to 5% shrinkage
Tertiary Santiago Formation 2% bulking to 6% shrinkage
It should be noted that the above factors are estimates only, based on preliminary data,
undocumented artificial fill, colluvium, and weathered very old paralic deposits/weathered
Santiago Formation may achieve higher shrinkage if organics or clay content is higher than
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anticipated. Final earthwork balance factors could vary. In this regard, it is recommended
that balance areas be reserved where grades could be adjusted up or down near the
completion of grading in order to accommodate any yardage imbalance for the project.
If the Client requires additional information regarding embankment factors, additional
studies could be provided upon request. Since the import fill source is currently unknown
at the time of this report, should evaluate the embankment factors for all proposed import.
UPDATED PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS
Based on our review ofthe geotechnical data acquired from previous work (GSI, 1989; and
N&M, 2009), our understanding of the proposed development plan, and our recent
geotechnical analyses , it is our opinion that the subject site is suitable for the currently
proposed residential development from a geotechnical engineering and geologic
viewpoint, provided that the recommendations presented in the following sections are
incorporated into the design and construction phases of site development. The primary
geotechnical concerns with respect to the proposed development and improvements are:
• The City of Cartsbad's proposed road widening plans, as currently designed, is not
compatible with the currently proposed site development.
Earth materials characteristics and depth to competent bearing materials.
On-going expansion and corrosion potentials ofthe onsite soils.
Permanent and temporary slope stability.
Suitability of existing undocumented fill materials for reuse as engineered fill and the
possible need for extensive import fill materials.
Erosiveness of site earth materials.
Potential for perched water dunng and following site development and the potential
effects perched water may have on global stability.
Perimeter conditions and planned improvements near the property boundary and
geogrid reinforced portions of the descending slopes.
Planned or remedial excavations near geogrid-reinforced slopes.
Potential for distress to improvements above a 1:1 (h:v) plane up from the heel of
the grid-reinforced zone.
Regional seismic activity.
Alternatives to the design which would increase the stability and/or reduce the need
for iy2:1 (h:v) slopes.
The conclusions and recommendations presented herein considerthese as well as other
aspects ofthe site. The engineering analyses, performed, concerning site preparation and
the recommendations presented herein have been completed using the information
provided and obtained during our field work. In the event that any significant changes are
made to proposed site development, the conclusions and recommendations contained in
this report shall not be considered valid unless the changes are reviewed and the
recommendations of this report are evaluated or modified in writing by this office.
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Foundation design parameters are considered preliminary until the foundation design,
layout, and structural loads are provided to this office for review. Significant findings from
our study are listed below.
1. The design of the geogrid slopes, proposed by the City of Cartsbad, should be
re-evaluated in light of the recent evaluation since they may impact the design
and/or performance of the proposed settlement-sensitive improvements. This
condition should be disclosed to all interested/affected parties.
2. Slope stability analyses indicate that the planned graded slopes will be surficially
stable. However, analyses indicate inadequate global static factors-of-safety for the
proposed geogrid-reinforced fill portion of the slope shown on Geologic Cross
Section A-A'. The non-code-compliant factors-of-safety may require the use of
longer/stronger grid reinforcement, more closely spaced geogrid reinforcement, the
use of higher strength import fill, and/or the use of higher compaction standards.
3. All import fill sources should be reviewed by aqualified geotechnical consultant and
no significant perched water should be present in the keyway and back-cut.
Subdrains are recommended to drain backcuts and keyways for the replacement
fills proposed in N&M (2009). The non-code-compliantfactors-of-safety may require
the use of longer/strong and/or more closely spaced geogrid reinforcements and/or
the use of higher compaction standards.
Unsupported temporary excavation walls ranging between 4 and 20 feet in gross
overall height and exposing talus debris, undocumented fill, Quaternary colluvium,
and weathered portions of the Quaternary very old paralic deposits and Tertiary
Santiago Formation should be constructed in accordance with CAL-OSHA
guidelines for Type C soils (i.e., 172:1 [h:v] slope). Unsupported temporary
excavation walls ranging between 4 and 20 feet in gross overall height and
exposing unweathered Quaternary very old paralic deposits and Tertiary Santiago
Formation should be constructed in accordance with CAL-OSHA guidelines for
Type B soils (i.e., 1:1 [h:v] slope). The above recommendations assume that
groundwater and/or running sands will not be exposed. All temporary slopes
should be observed by an engineering geologist or geotechnical engineer prior to
worker entry. Stockpiled soils, building materials, and heavy equipment should not
be placed, parked, nor operated within "H" feet of the tops of temporary slopes
(where "H" equals the gross height of the temporary slope).
4. All talus debris, undocumented artificial fill. Quaternary colluvium, and weathered
portionsof Quaternary very old paralic deposits and Tertiary Santiago Formation are
considered potentially compressible in their existing state and therefore, should not
be relied upon forthe support of planned settlement-sensitive improvements (i.e.,
residential structures, underground utilities, walls, pavements, swimming
pools/spas, etc.) and/or new planned fills. Where these soils are within the
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influence ofthe planned improvements and fills, these soils should be removed and
re-used as properly engineered fill.
5. In general, depths of remedial grading excavations for the removal of potentially
compressible soils throughout the site are anticipated to be on the order of 74- foot
to possibly up to 20 feet, locally (GSI, 1989). It should be noted that local variations
of unsuitable soil thicknesses are likely and deeper remedial grading excavations
cannot be precluded, and should be anticipated. Remedial grading excavations
should be completed below a 1:1 (h:v) projection down from the bottom, outermost
edge of proposed settlement-sensitive improvements and/or limits of new planned
fills unless constrained by property lines or geogrid-reinforced portions of the
descending slopes.
6. Previous laboratory testing by GSI (1989) indicates that the onsite earth materials
meet the criteria for detrimentally expansive soils as defined in Section 1803.5.3. of
the 2013 CBC (CBSC, 2013). Observations dunng our field study generally
substantiate our former conclusion. As indicated, in the 2013 CBC (CBSC, 2013),
foundations within the influence of expansive soils should be designed In
accordance with Sections 1808.6.1 or 1808.6.2. This implies the use of foundations
designed in accordance with "WRI/CRSI Design of Slab-on-Ground Foundations"
or "PTI Standard Requirements for Analysis of Shallow Concrete Foundations on
Expansive Soils" respectively produced by the Wire Reinforcement Institute and
Post Tension Institute. Alternatively, detnmentally expansive soils may be removed
from the site or selectively placed within the private roadway. Please note that
placement of expansive soils within the private roadway may increase the asphaltic
concrete structural section.
7. Soil pH, saturated resistivity, soluble sulfate, and chlonde testing indicates that a
representative sample of the onsite soils is neutral with respect to soil
acidity/alkalinity, is moderately corrosive to exposed, buried metals when saturated,
possesses negligible sulfate exposure ("Exposure Class SO") to concrete, and
although not negligible, is below the action level for chloride exposure (per State
of California Department of Transportation, 2003). GSI does not consult in
corrosion engineering. Therefore, additional comments and recommendations may
be obtained from a qualified corrosion engineer based on the level of corrosion
protection desired or required forthe project, as determined bythe project architect
and/or structural engineer.
8. Due to abundant deletenous debris within the existing undocumented fill, it may not
be cost-effective to screen and blend these materials for reuse. The use of import
fill sources should be considered in project planning.
9. In general and based upon the available data to date, regional groundwater is not
expected to be encountered during construction of the proposed residential
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development nor is it anticipated to adversely affect site development. However,
there is potential for perched water conditions to manifest along zones of
contrasting permeabilities (i.e., sandy/clayey fill lifts, geologic contacts, bedding
planes, sand lenses, joints, etc.) during and after construction. The potential for
perched water to occur dunng and after development should be disclosed to all
interested/affected parties.
10. It should be noted, that the 2013 CBC (CBSC, 2013) indicates that removals of
unsuitable soils be performed across all areas under the purview of the grading
permit, not just within the influence ofthe proposed residential structures. Relatively
deep removals may also necessitate a special zone of consideration, on
perimeter/confining areas. Based on the available subsurface data and assuming
1:1 (h:v) temporary construction slope gradients, the maximum width of this zone
may be on the order of 20 feet. Assuming 172:1 (h:v) temporary construction slope
gradients, the maximum width of this zone could potentially be upwards of 30 feet.
The actual width ofthis zone would be further evaluated dunng grading based on
the exposed conditions.
Any settlement-sensitive improvement (i.e., residential structures, site walls, brow
ditches, curbs, driveways, streets, swimming pools, flatwork, etc.), constructed
within this zone, may require deepened foundations, reinforcements, etc., or will
retain some potential for settlement and associated distress. This will require
proper disclosure to all interested/affected parties, should this condition exist at the
conclusion of grading.
11. Planned and remedial grading excavations should be coordinated such that any
geogrid reinforcement, supporting the outer 8 feet ofthe descending slopes, is not
daylighted nor damaged. This may limit the recommended remedial grading within
the proposed lots and require the use of deep foundation systems, geogrid
reinforced fills beneath the planned improvements, or other ground improvement
techniques. The limitations presented by the geognd reinforced slopes to
homeowner or Homeowner Association (HOA) improvements should be disclosed
to all interested/affected parties. Should the geogrid reinforcement within the
descending slopes be daylighted or damaged by excavation or landscape
development, it should be replaced in- kind underthe direction of GSI and the City
of Carlsbad Engineer.
12. The seismicity-acceleration values provided herein should be considered during the
design and construction of the proposed development.
13. General Earthwork and Grading Guidelines are provided atthe end ofthis report as
Appendix F. Specific recommendations are provided below.
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UPDATED PRELIMINARY EARTHWORK CONSTRUCTION RECOMMENDATIONS
General
All grading should conform to the guidelines presented in Section 1804 ofthe 2013 CBC,
the City of Carlsbad, as well as the recommendations contained herein. When code
references are not equivalent, the more stringent code should be followed. Prior to
grading, a meeting should be held between the Client, project civil consultant, and grading
contractor so that clarifications or amendments to our earthwork recommendations can be
provided, if needed, and to review the earthwork schedule.
During earthwork construction, all site preparation and the general grading procedures of
the contractor should be observed and the fill selectively tested by a representative(s) of
GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed
by this office and, if warranted, modified and/or additional recommendations will be
offered. All applicable requirements of local and national construction and general industry
safety orders, the Occupational Safety and Health Act (OSHA), and the Construction Safety
Act should be met. It is the onsite general contractor's and individual subcontractors'
responsibility to provide a safe working environment for our field staff who are onsite. GSI
does not consult in the area of safety engineering.
GSI also recommends that the contractor(s) take precautionary measure to protect work,
especially during the rainy season. Failure to do so may result in additional remedial
earthwork. Monitoring and documenting the adjacent properties prior to, and during
grading is strongly recommended. Due to the anticipated removal of debris laden fill and
replacement with a select material, quality reviews ofthe import source bythe geotechnical
consultant is recommended, prior to importation.
Demolition/Grubbing
1. Vegetation, and any miscellaneous deletenous debris generated from the
demolition of existing site improvements should be removed from the areas of
proposed grading/earthwork.
2. Cavities or loose soils remaining after demolition and site clearance should be
cleaned out and observed by the geotechnical consultant. The cavities should be
replaced with fill materials that have been moisture conditioned to at least optimum
moisture content and compacted to at least 90 percent ofthe laboratory standard.
Remedial Removals (Removal of Potentiallv Compressible Surficial Materials)
Where new planned fills or settlement-sensitive improvements are proposed, potentially
compressible undifferentiated talus debris/undocumented fill, existing undocumented fill
(i.e., "dumped fill"). Quaternary colluvium, and weathered portions ofthe Quaternary very
old paralic deposits and Tertiary Santiago Formation should be removed to expose
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unweathered Quaternary very old paralic deposits and Tertiary Santiago Formation (both
considered formational earth materials forthis project). With the exception ofthe existing,
debns-laiden "dumped fill," the removed soils may be reused as properly engineered fill
provided that major concentrations of organic and/or deletenous matenals have been
removed prior to placement. In general, the available subsurface data indicates that the
depth of remedial grading excavations to remove potentially compressible soils may range
between approximately 1 foot and upwards of 20 feet belowthe existing grades. However,
local deeper remedial excavations cannot be precluded and should be anticipated. The
removal of potentially compressible soils should be performed below a 1:1 (h:v) projection
down from the bottom, outermost edge of proposed settlement-sensitive improvements
and/or limits of new planned fills. Once the unsuitable soils have been removed, the
exposed unweathered very old paralic deposits and/or Santiago Formation should be
scarified approximately 6 to 8 inches, moisture conditioned as necessary to achieve the
soil's optimum moisture content and then be re-compacted to at least 90 percent ofthe
laboratory standard pnor to fill placement. All remedial removal excavations should be
observed bythe geotechnical consultant priorto scarification.
Temporarv Slopes
Unsupported temporary slopes ranging between 4 and 20 feet in gross overall height and
exposing talus debris, undocumented fill. Quaternary colluvium, and weathered portions
of the Quaternary very old paralic deposits and Tertiary Santiago Formation should be
constructed in accordance with CAL-OSHA guidelines for Type C soils (i.e., 172:1 [h:v]
slope). Similar heighttemporary slopes exposing unweathered Quaternaryvery old paralic
deposits and Tertiary Santiago Formation should be constructed in accordance with
CAL-OSHA guidelines for Type B soils (i.e., 1:1 [h:v] slope). The above recommendations
assume that groundwater and/or running sands will not be exposed. All temporary slopes
should be observed by a licensed engineenng geologist and/or geotechnical engineer
prior to worker entry into the excavation. Based on the exposed field conditions, inclining
temporary slopes to flatter gradients or the use of shoring may be necessary if adverse
conditions are observed. If temporary slopes conflict with property boundanes or other
boundary restrictions, shoring or alternating slot excavations may be necessary. The need
for shoring or alternating slot excavations could be further evaluated during grading.
Perimeter Conditions
It should be noted, thatthe 2013 CBC (CBSC, 2013) indicates that removals of unsuitable
soils be performed across all areas underthe purview ofthe grading permit, not just within
the influence of the proposed residential structures. Relatively deep removals may also
necessitate a special zone of consideration, on penmeter/confining areas. Based on the
available subsurface data and assuming 1:1 (h:v) temporary construction slope gradients,
the width of this zone may be on the order of 1 foot to 20 feet. Assuming 172:1 (h:v)
temporary construction slopes, the width of this zone could potentially be upwards of
30 feet. The actual width ofthis zone would be further evaluated during grading based on
the exposed conditions.
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Any proposed improvement orfuture homeowner improvements such as walls, swimming
pools, house additions, etc. that are located above a 1:1 (h:v) projection up from the
outermost limit ofthe remedial grading excavations will require deepened foundations that
extend below this plane. Other site improvements, such as pavements, constructed above
the aforementioned plane would retain some potential for settlement and associated
distress, which may require increased maintenance/repair or replacement. This potential
should be disclosed to all interested/affected parties should remedial grading excavations
be constrained by property lines.
Overexcavation
Uniform support of foundations should be provided by overexcavating any unweathered
very old paralic deposits and/or Santiago Formation exposed within 2 feet of the lowest
foundation element, following the remedial removal of unsuitable soils. Since plans
showing foundation layout and footing depths are currently unavailable, the recommended
overexcavation should be completed to at least 4 feet below finish pad grade, on a
preliminary basis. Overexcavated materials should be replaced with engineered fill
compacted to at least 90 percent ofthe laboratory standard (ASTM D 1557). The bottom
of the overexcavation should be sloped toward the private road or approved drainage
facilities, scarified at least 6 to 8 inches, moisture-conditioned as necessary to achieve the
soil's optimum moisture content, and then be recompacted to at least 90 percent of the
laboratory standard prior to fill placement. Overexcavation should be completed across
the entire building pad, as necessary, since building layouts are currently unknown.
Overexcavations should be observed bythe geotechnical consultant priorto scarification.
The maximum to minimum fill thickness across building pads should not exceed a ratio of
3:1 (maximum:minimum).
Engineered Fill Placement
Engineered fill should be relatively free of deleterious debris, well blended, placed in thin
lifts, moisture conditioned, and mixed to minimally achieve the soil's optimum moisture
content, and then be mechanically compacted to at least 90 percent of the laboratory
standard (ASTM D 1557). Engineered fill placement should be observed and selectively
tested for moisture content and compaction bythe geotechnical consultant. Fill materials
should not contain rock constituents greater than 12 inches in any dimension. Local utility
requirements may be further restrictive on maximum particle sizes allowed in trench backfill
and may be significantly less than 12 inches.
Import Fill Materials
Any import fill materials used on this project should have similar expansive and plastic
characteristics with the onsite soils. Soils used forthe planned grid reinforced slopes have
a minimum cohesion of 176 pounds per square foot (psf) and a minimum phi angle of
32 degrees. Import for underground utility backfill should complywith local underground
utility company requirements. All import fill material should be tested by GSI prior to
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placement within the site. GSI would also request environmental documentation (e.g.,
Phase I Environmental Site Assessment) pertaining to offsite export site, to evaluate ifthe
proposed import could present an environmental risk to the planned residential
development. At least three (3) business days of lead time will be necessary for the
required laboratory testing and document review.
Subdrains
Subdrains are recommended in natural drainage courses where the as-graded (i.e.,
planned plus remedial) fill thickness exceeds 10 feet. Subdrains are also recommended
within the heel ofthe keyways forthe grid reinforced slopes proposed by N&M (2009).
Subdrains should minimally consist of 4-inch diameter, SDR 35 perforated drain pipe with
perforations oriented down. The drain pipe should be encased in at least 1 cubic foot of
clean, crushed y4-inch to 172-inch gravel. The pipe and gravel should be completely
wrapped in Mirafi MON filter fabric or an approved equivalent. The perforated pipe
diameter should be increase to 6 inches for any subdrain exceeding 500 lineal feet in
length.
Excavation Observation and Monitoring (All Excavations)
When excavations are made adjacent to an existing improvement (i.e., utility, wall, road,
building, etc.) there is a risk of some damage even if a well designed system of excavation
is planned and executed. We recommend, therefore, that a systematic program of
observations be made before, during, and after construction to determine the effects
(if any) of construction on existing improvements.
We believe that this is necessary for two reasons: First, if excessive movements (i.e., more
than 72-inch) are detected earty enough, remedial measures can be taken which could
possibly prevent serious damage to existing improvements. Second, the responsibility for
damage to the existing improvement can be determined more equitably ifthe cause and
extent of the damage can be determined more precisely.
Monitoring should include the measurement ofany horizontal and vertical movements of
the existing structures/improvements. Locations and type ofthe monitoring devices should
be selected prior to the start of construction. The program of monitonng should be agreed
upon between the project team, the site surveyor and the Geotechnical
Engineer-of-Record, prior to excavation.
Reference points on existing walls, buildings, and other settlement-sensitive improvements.
These points should be placed as low as possible on the wall and building adjacent to the
excavation. Exact locations may be dictated by critical points, such as bearing walls or
columns for buildings; and surface points on roadways or curbs near the top of the
excavation.
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For a survey monitonng system, an accuracy of a least 0.01 foot should be required.
Reference points should be installed and read initially prior to excavation. The readings
should continue until all construction below ground has been completed and the
permanent backfill has been broughtto final grade.
The frequency of readings will depend upon the results of previous readings and the rate
of construction. Weekly readings could be assumed throughout the duration of
construction with daily readings dunng rapid excavation near the bottom ofthe excavation.
The reading should be plotted by the Surveyor and then reviewed by the Geotechnical
Engineer. In addition to the monitoring system, it would be prudent for the Geotechnical
Engineer and the Contractorto make a complete inspection ofthe existing structures both
before and after construction. The inspection should be directed toward detecting any
signs of damage, particularty those caused by settlement. Notes should be made and
pictures should be taken where necessary.
It is recommended that all excavations be observed bythe Geologist and/or Geotechnical
Engineer. Any fill which is placed in excavations should be tested and approved by the
geotechnical consultant if used for engineered purposes. Should the observation reveal
any unforseen hazard, the Geologist or Geotechnical Engineer will recommend treatment.
Please inform GSI at least 24 hours pnor to any required site observation.
PRELIMINARY FOUNDATION RECOMMENDATIONS
General
The preliminary foundation design and construction recommendations, presented herein,
are based on the geotechnical data contained in GSI (1989) and N&M (2009) and our
recent field studies, laboratory testing, and engineering evaluations performed in
conjunction with this update. The following preliminary foundation design and construction
recommendations are presented as minimum criteria from a geotechnical engineering
viewpoint. Previous expansion index testing ,performed on representative samples ofthe
onsite soils, indicates low to critically (very high) expansive soil conditions at the site. In
order to mitigate the damaging effects of expansive soils on the residential foundations,
it is recommended that the foundation systems be designed in accordance with
Sections 1808.6.1 or 1808.6.2 of the 2013 CBC. As such, GSI is providing preliminary
design and construction recommendationsfor post-tensioned and mat foundation systems
for lowto critically expansive soil conditions (E. I. = 21 to >130).
This section presents minimum design criteria for the design of foundations, concrete
slab-on-grade floors, and other elements possibly applicable to the project. These criteria
should not be considered as substitutes for actual designs by the structural engineer.
Recommendations by the project's design-structural engineer or architect, which may
exceed the geotechnical consultant's recommendations, should take precedence overthe
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following minimum requirements. The foundation systems recommended herein may be
used to support the proposed residences provided they are entirely founded in engineered
fill tested and approved by GSI that overlies dense formational earth materials.
In the event that the information concerning the proposed development plan is not correct,
or any changes in the design, location or loading conditions ofthe proposed structures are
made, the conclusions and recommendations contained in this report shall not be
considered valid unless the changes are reviewed and conclusions of this report are
modified or approved in writing by this office. Upon request, GSI could provide additional
input/consultation regarding soil parameters, as they relate to foundation design.
General Foundation Design
1. The foundation systems should be designed and constructed in accordance with
guidelines presented in the 2013 CBC.
2. An allowable beanng value of 1,500 psf may be used for the design of footings that
maintain a minimum width of 12 inches and a minimum depth of 12 inches (below
the lowest adjacent grade) and are founded entirely into properlv engineered fill.
This value may be increased by 20 percent for each additional 12 inches in footing
embedment to a maximum value of 2,500 psf. These values may be increased by
one-third when considering short duration seismic or wind loads. Isolated pad
footings should have a minimum dimension of at least 24 inches square and a
minimum embedment of 24 inches below the lowest adjacent grade into properly
engineered fill. Foundation embedment excludes any landscaped zones, concrete
slabs-on-grade, and/or slab undertayment.
3. Passive earth pressure in properly compacted silty or clayey sand fill may be
computed as an equivalent fluid having a density of 250 pcf, with a maximum earth
pressure of 2,500 psf for footings founded into property engineered fill. Lateral
passive pressures for shallow foundations within 2013 CBC setback zones or within
the influence of retaining walls should be reduced following a review by the
geotechnical engineer unless proper setbacks can be established.
4. For lateral sliding resistance, a 0.35 coefficient of friction may be utilized for a
concrete to soil contact when multiplied by the dead load.
5. When combining passive pressure and frictional resistance, the passive pressure
component should be reduced by one-third.
6. All footing setbacks from slopes should comply with Figure 1808.7.1 of the
2013 CBC. GSI recommends a minimum honzontal setback distance of 7 feet as
measured from the bottom (i.e., bearing elevation), outboard edge ofthe footing to
the slope face.
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7. Footings for structures adjacent to retaining walls should be deepened so as to
extend below a 1:1 projection from the heel ofthe wall should this condition occur.
Alternatively, walls may be designed to accommodate structural loads from
buildings or appurtenances as described in the "Retaining Wall" section of this
report.
8. All interior and exterior column footings should be tied to the penmeter wall footings
in at least two directions. The base of the reinforced grade beam should be at the
same elevation as the adjoining footings.
9. Provided the recommendations in this report are properly followed, foundation
systems should be minimally designed to accommodate a total settlement of
172 inches and a differential settlement of at least 1 inch in a 40-foot horizontal span
(angular distortion = 1/480). This estimated settlement should be re-evaluated once
the final foundation layouts, loads, and final grading configuration become
available. These preliminary settlement values do not apply to improvements
constructed within 2013 CBC setbacks or within the influence of unmitigated soils.
In addition, these values do not take seismic effects from strong ground motion into
account.
PRELIMINARY FOUNDATION CONSTRUCTION RECOMMENDATIONS
Post-Tensioned Foundations
Post-tension foundations may be used to mitigate the damaging effects of expansive soils
on the planned residential foundations and slab-on-grade floors. The post-tension
foundation designer may elect to exceed these minimal recommendations to increase slab
stiffness performance. Post-tension (PT) design may be either ribbed or mat-type. The
latter is also referred to as uniform thickness foundation (UTF). The use of a UTF is an
alternative to the traditional ribbed-type. The UTF offers a reduction in grade beams. That
is to say a UTE typically uses a single perimeter grade beam and possible "shovel"
footings, but has a thicker slab than the ribbed-type.
The information and recommendations presented in this section are not meant to
supercede design by a registered structural engineer or civil engineer qualified to perform
post-tensioned design. Post-tensioned foundations should be designed using sound
engineering practice and be in accordance with local and 2013 CBC requirements. Upon
request, GSI can provide additional data/consultation regarding soil parameters as related
to post-tensioned foundation design.
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From a soil expansion/shnnkage standpoint, a common contributing factor to distress of
structures using post-tensioned slabs is a "dishing" or "arching" ofthe slabs. This is caused
by the fluctuation of moisture content in the soils below the penmeter of the slab pnmarily
due to onsite and offsite irrigation practices, climatic and seasonal changes, and the
presence of expansive soils. When the soil environment surrounding the extenor ofthe
slab has a higher moisture content than the area beneath the slab, moisture tends to
migrate inward, underneath the slab edges to a distance beyond the slab edges referred
to as the moisture vanation distance. When this migration of water occurs, the volume of
the soils beneath the slab edges expands and causes the slab edges to lift in response.
This is referred to as an edge-lift condition. Conversely, when the outside soil environment
is drier, the moisture transmission regime is reversed and the soils underneath the slab
edges lose their moisture and shrink. This process leads to dropping of the slab at the
edges, which leads to what is commonly referred to as the center lift condition. A
well-designed, post-tensioned slab having sufficient stiffness and rigidity provides a
resistance to excessive bending that results from non-uniform swelling and shrinking slab
subgrade soils, particularly within the moisture variation distance, near the slab edges.
Other mitigation techniques typically used in conjunction with post-tensioned slabs consist
of a combination of specific soil pre-saturation and the construction of a perimeter "cut-off'
wall grade beam. Soil pre-saturation consists of moisture conditioning the slab subgrade
soils prior to the post-tension slab construction. This effectively reduces soil moisture
migration from the area located outside the building toward the soils underlying the
post-tension slab. Perimeter cut-off walls are thickened edges of the concrete slab that
impedes both outward and inward soil moisture migration.
Slab Subgrade Pre-Soaking
Pre-moistening of the slab subgrade soil is recommended owing to expansive soil
conditions at the site. The moisture content ofthe subgrade soils should be equal to or
greater than optimum moisture to a depth equivalent to the perimeter grade beam or cut-
off wall depth in the slab areas (typically 12,18,24, and 30 inches for low, medium, high,
and very high expansive soil conditions, respectively).
Pre-moistening and/or pre-soaking should be evaluated by the soils engineer 72 hours
prior to vapor retarder placement. In summary:
EXPANSION
INDEX PAD SOIL MOISTURE CONSTRUCTION
METHOD
SOIL MOj^TURE
RETENTION
Low
(21-50)
Upper 12 inches of pad soil
moisture 2 percent over
optimum (or 1.2 times)
Wetting and/or
reprocessing
Periodically wet or cover
with plastic after trenching.
Evaluation 72 hours prior to
placement of concrete.
The Kevane Company, Inc.
APNs 167-230-24 & -25
File:e:\wp12\6600\6635a.ruge GeoSoils, Inc.
W.O. 6653-A-SC
Revised April 22, 2014
Page 24
EXPANSION
INDEX PAD SOIL MOISTURE CONSTRUCTION I
" METHOD
1 SOILvlMOiSTURE
RETENTION
Medium
(51-90)
Upper 18 inches of pad soil
moisture 2 percent over
optimum (or 1.2 times)
Berm and flood or wetting
and reprocessing
Periodically wet or cover
with plastic after trenching.
Evaluation 72 hours prior to
placement of concrete.
High
(91-130)
Upper 18 inches of pad soil
moisture 3 percent over
optimum (or 1.3 times)
Berm and flood or wetting
and reprocessing
Periodically wet or cover
with plastic after trenching.
Evaluation 72 hours prior to
placement of concrete.
Very High
(131 and above)
Upper 24 inches of pad soil
moisture 4-5 percent over
optimum (or 1.4-1.5 times)
Berm and flood or wetting
and reprocessing
Periodically wet or cover
with plastic after trenching.
Evaluation 72 hours prior to
placement of concrete. At
24 hours an additional
evaluation should be
performed.
Perimeter Cut-Off Walls
Penmeter cut-off walls should be at least 12,18,24,30 inches deep for low, medium, high,
and very high expansive soil conditions, respectively. The cut-off walls may be integrated
into the slab design or independent ofthe slab. The cut-off walls should be a minimum of
6 inches thick (wide). The bottom ofthe perimeter cut-off wall should be designed to resist
tension, using cable or reinforcement per the structural engineer.
Post-Tensioned Foundation Design
The following recommendations for design of post-tensioned slabs have been prepared
in general compliance with the requirements of the recent Post Tensioning Institute's
(PTI's) publication titled "Design of Post-Tensioned Slabs on Ground, Third Edition"
(PTI, 2004), together with it's subsequent addendums (PTI, 2008).
Soil Support Parameters
The recommendations for soil support parameters have been provided based on the
typical soil index properties for soils that are low to very high in expansion potential. The
soil index properties are typically the upper bound values based on our experience and
practice in the southern California area. The following table presents suggested minimum
coefficients to be used in the Post-Tensioning Institute design method.
The Kevane Company, Inc.
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Revised April 22, 2014
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Thornthwaite Moisture Index -20 inches/year
Correction Factor for Irrigation 20 inches/year
Depth to Constant Soil Suction 7 feet or overexcavation
depth to bedrock
Constant soil Suction (pf) 3.6
Moisture Velocity 0.7 inches/month
Plasticitv Index (P.l.)* 15-45
* - The effective plasticity index should be evaluated for the upper
7 to 15 feet of earth materials.
Based on the above, the recommended soil support parameters are tabulated below:
DESIGN
PARAMETER'S
VERY LOW Tp LOW
EXPANSION
(E.I. = 0-50)'
MEDIUM
EXPANSION
(E.I. = 51-90i
HIGH
EXPANSION •
(E.I. = §1.130) '
VERY HIGH
^•EXPANSION
' (E.I. >130)
e„ center lift 9.0 feet 8.7 feet 8.5 feet 7.5 feet
e^ edge lift 5.2 feet 4.5 feet 4.0 feet 3.25 feet
y„ center lift 0.4 inches 0.5 inches 0.66 inches 1.1 inches
Vm edge lift 0.7 inch 1.3 inch 1.7 inches 2.5 inches
Bearing Value 1,000 psf 1,000 psf 1,000 psf 1,000 psf
Lateral Pressure 250 psf 175 psf 150 psf 125 psf
Subgrade Modulus (k) 100 pci/inch 85 pci/inch 70 pci/inch 60 pci/inch
Minimum Perimeter
Footing Embedment 12 inches 18 inches 24 inches 30 inches
Internal bearing values within the perimeter ofthe post-tension slab may be increased to 1,500 psf for
a minimum embedment of 12 inches, then by 20 percent for each additional foot of embedment to a
maximum of 2,500 psf.
'^'AS measured below the lowest adjacent compacted subgrade surface without landscape layer or sand
underlayment.
Note: The use of open bottomed raised planters adjacent to foundations will require more onerous design
parameters.
I
I
The parameters are considered minimums and may not be adequate to represent all
expansive soils and site conditions such as adverse drainage and/or improper
landscaping and maintenance. The above parameters are applicable provided the
structure has positive drainage that is maintained away from the structure. In addition, no
trees with significant root systems are to be planted within 15 feet of the perimeter of
foundations. Therefore, it is important that information regarding drainage, site
maintenance, trees, settlements, and effects of expansive soils be passed on to future all
interested/affected parties. The values tabulated above may not be appropriate to account
The Kevane Company, Inc.
APNs 167-230-24 & -25
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w.o. 6653-A-SC
Revised April 22, 2014
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I
for possible differential settlement of the slab due to other factors, such as excessive
settlements. If a stiffer slab is desired, alternative Post-Tensioning Institute ([PTI] third
edition) parameters may be recommended.
Mat Foundations
In lieu of using a post-tensioned foundation to resist expansive soil effects, the Client may
consider a mat foundation which uses steel bar reinforcement instead of post-tensioned
cables. The structural engineer may supersede the following recommendations based on
the planned building loads and use. WRI (Wire reinforcement institute) methodologies for
design may be used.
Mat Foundation Design
The design of mat foundations should incorporate the vertical modulus of subgrade
reaction. This value is a unit value for a 1-foot square footing and should be reduced in
accordance with the following equation when used with the design of larger foundations.
This is assumes that the beanng soils will consist of engineered fills with an average
relative compaction of 90 percent of the laboratory (ASTM D 1557), overlying dense
formational earth materials.
B + 1
2B
where: Kg = unit subgrade modulus
KR = reduced subgrade modulus
B = foundation width (in feet)
The modulus of subgrade reaction (Kg) and effective plasticity index (PI) to be used in mat
foundation design for vanous expansive soil conditions are presented in the following
table.
LOW EXPANSION
(Ej. 0-50)
MEDIUM EXPANSION '
. (E.I. = 51-90)
HIGH EXP/tNSIpN
(E.I. = 91-130)
VERY HIGH
- EXP/^NSpJ^'
(E.L'> 130)
Ks =100 pci/inch, PI <15 Kg =85 pci/inch, PI = 25 Kg =70 pci/inch, PI = 35 Kg =60 pci/inch, PI
= 45
Reinforcement bar sizing and spacing for mat slab foundations should be provided by the
structural engineer. Mat slabs may be uniform thickness foundations (UTF) or may
incorporate the use of edge footings for moisture cut-off barriers as recommended herein
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Revised April 22, 2014
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for post-tension foundations. Edge footings should be a minimum of 6 inches thick. The
bottom ofthe edge footing should be designed to resist tension, using reinforcement per
the structural engineer. The need and arrangement of interior grade beams (stiffening
beams) will be in accordance with the structural consultant's recommendations. The
recommendations for a mat type of foundation assume that the soils below the slab are
compacted fill overtying dense, unweathered formational earth matenals. The parameters
herein are to mitigate the effects of expansive soils and should be modified to mitigate the
effects of the total and differential settlements reported earlier in this report.
Specific pre-moistening/pre-soaking and moisture testing of the slab subgrade are
recommended for expansive soil conditions (E.I. > 20 and P.l. of 15 or greater), as
previously provided in this report. Slab subgrade moisture conditioning/pre-soaking
should conform to the recommendations previously provided for post-tension foundation
systems.
Confirmation Testing for Final Foundation Design
Following the completion of site grading, the expansion index, plasticity index, subgrade
modulus, corrosion potential of soils exposed near finish grade should be re-evaluated.
Although not anticipated, the results of the recommended testing may require
amendments to these preliminary recommendations.
Alternative Foundations
Based on the available preliminary drawings, the site pads and residential foundations
may be altered to provide a more cost-effective grading solution and utilize drilled-pier-
supported improvements. Should these alternative grading solutions be requested,
GSI will provide additional recommendations with regard to drilled pier design and
construction, and alternative recommendations for grading.
SOIL MOISTURE TRANSMISSION CONSIDERATIONS
GSI has evaluated the potential for vapor or water transmission through the concrete floor
slab, in light of typical floor covenngs and improvements. Please note that slab moisture
emission rates range from about 2 to 27 lbs/ 24 hours/1,000 square feet from a typical slab
(Kanare, 2005), while floor covering manufacturers generally recommend about
3 lbs/24 hours as an upper limit. The recommendations in this section are not intended
to preclude the transmission of water or vapor through the foundation or slabs.
Foundation systems and slabs shall not allow water or water vapor to enter into the
structure so as to cause damage to another building component or to limit the installation
of the type of flooring matenals typically used for the particular application (State of
California, 2013). These recommendations may be exceeded or supplemented by a water
"proofing" specialist, project architect, or structural consultant. Thus, the client will need
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to evaluate the following in light of a cost vs. benefit analysis (owner expectations and
repairs/replacement), along with disclosure to all interested/affected parties. It should also
be noted that vapor transmission will occur in new slab-on-grade floors as a result of
chemical reactions taking place within the cunng concrete. Vapor transmission through
concrete floor slabs as a result of concrete curing has the potential to adversely affect
sensitive floor coverings depending on the thickness of the concrete floor slab and the
duration of time between the placement of concrete, and the floor covering. It is possible
that a slab moisture sealant may be needed pnor to the placement of sensitive floor
covenngs if a thick slab-on-grade floor is used and the time frame between concrete and
floor covenng placement is relatively short.
Considering the E.I. test results presented herein, and known soil conditions in the region,
the anticipated typical water vapor transmission rates, floor coverings, and improvements
(to be chosen by the Client and/or project architect) that can tolerate vapor transmission
rates without significant distress, the following alternatives are provided:
• Concrete slab-on-grade floors (including garage slabs) should be a minimum of
5 inches thick. The project structural engineer may require thicker slabs-on-grade
to mitigate expansive soil conditions.
• Concrete slab underlayment should consist of a 15-mil vapor retarder, or equivalent,
with all laps sealed per the 2013 CBC and the manufacturer's recommendation.
The vapor retarder should comply with the ASTM E 1745 - Class A critena, and be
installed in accordance with ACI 302.1 R-04 and ASTM E 1643.
The 15-mil vapor retarder (ASTM E 1745 - Class A) shall be installed per the
recommendations ofthe manufacturer, including aH penetrations (i.e., pipe, ducting,
rebar, etc.).
• Concrete slabs, including the garage areas, shall be underlain by 2 inches of clean,
washed sand (SE >. 30) above a 15-mil vapor retarder (ASTM E-1745 - Class A, per
Engineenng Bulletin 119 [Kanare, 2005]) installed perthe recommendations ofthe
manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). The
manufacturer shall provide instructions for lap sealing, including minimum width of
lap, method of sealing, and either supply or specify suitable products for lap sealing
(ASTM E 1745), and per code.
ACI 302.1 R-04 (2004) states "If a cushion or sand layer is desired between the
vapor retarder and the slab, care must be taken to protect the sand layer from
taking on additional water from a source such as rain, curing, cutting, or cleaning.
Wet cushion or sand layer has been directly linked in the past to significant
lengthening of time required for a slab to reach an acceptable level of dryness for
floor covenng applications." Therefore, additional observation and/or testing will be
necessary for the cushion or sand layer for moisture content, and relatively uniform
thicknesses, prior to the placement of concrete.
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• The vapor retarder shall be undedain by a capillary break consisting of at least
4 inches of clean crushed gravel with a maximum dimension of % inch (less than
5 percent passing the No. 200 sieve).
• Concrete for foundations and slab-on-grade floors should be low permeability (i.e.,
Exposure Class P1 in Table 4.3.1 of ACI 318-08). This does not supercede
Table 4.3.1 of Chapter 4 of the ACI (2008) for corrosion or other corrosive
requirements. Additional concrete mix design recommendations should be
provided by the structural consultant and/or waterproofing specialist. Concrete
finishing and workablity should be addressed by the structural consultant and a
waterproofing specialist.
• Where slab water/cement ratios are as indicated herein, and/or admixtures used,
the structural consultant should also make changes to the concrete in the grade
beams and footings in kind, so that the concrete used in the foundation and slabs
are designed and/or treated for more uniform moisture protection.
• The owner(s) should be specifically advised which areas are suitable tortile floonng,
vinyl flooring, or other types of water/vapor-sensitive flooring and which are not
suitable. In all planned floor areas, flooring shall be installed perthe manufactures
recommendations.
• Additional recommendations regarding water or vapor transmission should be
provided by the architect/structural engineer/slab or foundation designer and
should be consistent with the specified floor coverings indicated by the architect.
Regardless ofthe mitigation, some limited moisture/moisture vapor transmission through
the slab should be anticipated. Construction crews may require special training for
installation of certain product(s), as well as concrete finishing techniques. The use of
specialized product(s) should be approved by the slab designer and water-proofing
consultant. Atechnical representative ofthe flooring contractor should reviewthe slab and
moisture retarder plans and provide comment prior to the construction of the foundations
or improvements. The vapor retarder contractor should have representatives onsite during
the initial installation.
WALL DESIGN PARAMETERS CONSIDERING EXPANSIVE SOILS
General
Based on our review of WE&S (2013), there are no proposed retaining walls associated
with the project at this time. However, should they be needed or incorporated into
individual homeowner landscape improvements, we have included recommendationsfor
the design and construction of conventional masonry retaining walls. Recommendations
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for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and
would be based on site specific conditions.
Conventional Retaining Walls
The design parameters provided below assume that either very low expansive soils
(typically Class 2 permeable filter material or Class 3 aggregate base) or native onsite
materials with an expansion index up to 20 are used to backfill any retaining wall. Please
note that the onsite likely do not meet this criteria. The type of backfill (i.e., select or
native), should be specified by the wall designer, and cleariy shown on the plans. Building
walls, below grade, should be water-proofed. Waterproofing should also be provided for
site retaining walls in order to reduce the potential for efflorescence staining.
Preliminary Retaining Wall Foundation Design
Preliminary foundation design for retaining walls should incorporate the following
recommendations:
Minimum Footing Embedment - 18 inches below the lowest adjacent grade
(excluding landscape layer [upper 6 inches]).
Minimum Footing Width - 24 inches
Allowable Bearing Pressure - An allowable bearing pressure of 2,500 pcf may be
used in the preliminary design of retaining wall foundations provided that thefooting
maintains a minimum width of 24 inches and extends at least 18 inches into
approved engineered fill overiying dense formational materials. This pressure may
be increased by one-third for short-term wind and/or seismic loads.
Passive Earth Pressure - A passive earth pressure of 250 pcf with a maximum
earth pressure of 2,500 psf may be used in the preliminary design of retaining wall
foundations provided the foundation is embedded into property compacted silty to
clayey sand fill.
Lateral Sliding Resistance - A 0.35 coefficient of friction may be utilized for a
concrete to soil contact when multiplied by the dead load. When combining
passive pressure and frictional resistance, the passive pressure component should
be reduced by one-third.
Backfill Soil Density - Soil densities ranging between 105 pcf and 115 pcf may be
used in the design of retaining wall foundations. This assumes an average
engineered fill compaction of at least 90 percent ofthe laboratory standard (ASTM
D 1557).
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Any retaining wall footings near the perimeter ofthe site will likely need to be deepened
into unweathered very old paralic deposits or unweathered Santiago Formation for
adequate vertical and lateral bearing support. All retaining wall footing setbacks from
slopes should comply with Figure 1808.7.1 ofthe 2013 CBC. GSI recommends aminimum
horizontal setback distance of 7 feet as measured from the bottom, outboard edge ofthe
footing to the slope face.
Restrained Walls
Any retaining walls that will be restrained prior to placing and compacting backfill material
or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid
pressure (EFP) of 55 pcf and 65 pcf for select and very low expansive native backfill,
respectively. The design should include any applicable surcharge loading. For areas of
male or re-entrant corners, the restrained wall design should extend a minimum distance
of twice the height ofthe wall (2H) laterally from the corner.
Cantilevered Walls
The recommendations presented below are for cantilevered retaining walls up to 10 feet
high. Design parameters for walls less than 3 feet in height may be superceded by County
of San Diego regional standard design. Active earth pressure may be used for retaining
wall design, provided the top of the wall is not restrained from minor deflections. An
equivalent fluid pressure approach may be used to compute the horizontal pressure
against the wall. Appropriate fluid unit weights are given below for specific slope gradients
ofthe retained material. These do not include other superimposed loading conditions due
to traffic, structures, seismic events or adverse geologic conditions. When wall
configurations are finalized, the appropriate loading conditionsforsuperimposed loads can
be provided upon request.
For preliminary planning purposes, the structural consultant/wall designer should
incorporate the surcharge of traffic on the back of retaining walls where vehicular traffic
could occur within horizontal distance "H" from the back of the retaining wall (where "H"
equals the wall height). The traffic surcharge may be taken as 100 psf/ft in the upper 5 feet
of backfill for light truck and cars traffic. This does not include the surcharge of parked
vehicles which should be evaluated at a higher surcharge to account for the effects of
seismic loading. Equivalent fluid pressures for the design of cantilevered retaining walls
are provided in the following table:
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SURFACE SLOPE OF
RETAILED MATERIAL
(HORIZGNTAIlrVERTICAL)
EQUIVALENT
FLUID WEIGHT P.C.F.
(SELECT BACKFILL)<^
1' EQUIVALENT
FLUID WEIQHT.P.C.F.
'(DATIVE BACKFILL)!'*
Level'^>
2 to 1
38
55
45
60
Level backfill behind a retaining wall is defined as compacted earth materials, properly drained, without
a slope for a distance of 2H behind the wall, where H is the height of the wall.
SE >_ 30, P.l. < 15, E.I. < 21, and <_ 10% passing No. 200 sieve.
E.I. = Oto 50, SE > 30, P.l. < 15, E.I. < 21, and < 15% passing No. 200 sieve.
Seismic Surcharge
For engineered retaining walls with more than 6 feet of retained materials, as measured
vertically from the bottom of the wall footing at the heel to daylight, GSI recommends that
the walls be evaluated for a seismic surcharge (in general accordance with 2013 CBC
requirements). The site walls in this category should maintain an overturning
Factor-of-Safety (FOS) of approximately 1.25 when the seismic surcharge (increment), is
applied. For restrained walls, the seismic surcharge should be applied as a uniform
surcharge load from the bottom of the footing (excluding shear keys) to the top of the
backfill atthe heel ofthe wall footing. This seismic surcharge pressure (seismic increment)
may be taken as 15H where "H" for retained walls is the dimension previously noted as the
height of the backfill to the bottom of the footing. The resultant force should be applied at
a distance 0.6 H up from the bottom of the footing. For the evaluation of the seismic
surcharge, the bearing pressure may exceed the static value by one-third, considering the
transient nature ofthis surcharge. For cantilevered walls, the pressure should be applied
as an inverted triangular distribution using 15H. For restrained walls, the pressure should
be applied as a rectangular distribution. Please note this is for local wall stability only.
The 15H is derived from a Mononobe-Okabe solution for both restrained cantilever walls.
This accounts for the increased lateral pressure due to shakedown or movement of the
sand fill soil in the zone of influence from the wall or roughly a 45° - (t)/2 plane away from
the back ofthe wall. The 15H seismic surcharge is derived from the formula:
PH = %.aH»Y.H
Where:
ah
Y.
H
Seismic increment
Probabilistic horizontal site acceleration with a percentage of
"g"
total unit weight (115 to 125 pcf for site soils @ 90% relative
compaction).
Height ofthe wall from the bottom ofthe footing or point of pile
fixity.
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Retaining Wall Backfill and Drainage
Positive drainage must be provided behind all retaining walls in the form of gravel wrapped
in geofabric and outlets. A backdrain system is considered necessary for retaining walls
that are 2 feet or greater in height. Details 1, 2, and 3, present the backdrainage options
discussed below. Backdrains should consist of a 4-inch diameter perforated PVC or ABS
pipe encased in either Class 2 permeable filter material or %-inch to 172-inch gravel
wrapped in approved filter fabric (Mirafi 140 or equivalent). For select backfill, the filter
material should extend a minimum of 1 horizontal foot behind the base ofthe walls and
upward at least 1 foot. For native backfill that has up to E.I. = 20, continuous Class 2
permeable drain materials should be used behind the wall. This material should be
continuous (i.e., full height) behind the wall, and it should be constructed in accordance
with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited
access and confined areas, (panel) drainage behind the wall may be constructed in
accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain).
Materials with an expansion index (E.I.) potential of greater than 20 should not be used as
backfill for retaining walls. Retaining wall backfill materials should be moisture conditioned
and mixed to achieve the soil's optimum moisture content, placed in relatively thin lifts (6 to
10 inches), and compacted to at least 90 percent relative compaction. For more onerous
expansive situations, backfill and drainage behind the retaining wall should conform with
Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill).
Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than
±100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes,
only, in walls higher than 2 feet, is not recommended. The surface ofthe backfill should
be sealed by pavement or the top 18 inches compacted with native soil (E.I. < 50). Proper
surface drainage should also be provided. For additional mitigation, consideration should
be given to applying a water-proof membrane to the back of all retaining structures. The
use of a waterstop should be considered for all concrete and masonry joints.
Wall/Retaining Wall Footing Transitions
Site walls are anticipated to be founded on footings designed in accordance with the
recommendations in this report. Should wall footings transition from cut to fill, the
structural consultant/wall designer may specify either:
a) A minimum of a 2-foot overexcavation and recompaction of cut materials for a
distance of 2H, from the point of transition.
b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints
or crack control joints) such that a angular distortion of 1/360 for a distance of 2H
on either side ofthe transition may be accommodated. Expansion joints should be
placed no greater than 20 feet on-center, in accordance with the structural
engineer's/wall designer's recommendations, regard less of whether or not transition
conditions exist. Expansion joints should be sealed with aflexible, non-shrink grout.
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structural footing or
settlement-sensitive improvement
(1) Waterproofing
membrane
CMU or
reinforced-concrete
wall
r- Proposed grade I
\ sloped to drain
\ per precise civil
\ drawings
\ (5) Weep hole
Footing and wall
design by oihers--:^
Native backfill
1:1 (h:v) or flatter
backcut to be
properly benched
(6) Footing
(1) Waterproofing membrane.
(2) Gravel: Clean, crushed, % to 1)^ inch.
(3) Filter fabric: Mirafi MON or approved equivalent.
(4) Pipe: 4-lnch-dlameter perforated PVC, Schedule 40, or approved alternative with minimum
of 1 percent gradient sloped to suitable, approved outlet point (perforations down).
(5) Weep hole: Minimum 2-Inch diameter placed at 20-foot centers along the wall and placed
3 inches above finished surface. Design civil engineer to provide drainage at toe of wall.
No weep holes for below-grade walls.
(6) Footing: |f bench is created behind the footing greater than the footing width, use
level fill or cut natural earth materials. An additional "heel" drain will likely be required by
geotechnical consultant.
RETAINING WALL DETAIL - ALTERNATIVE A Detail 1
(1) Waterproofing
membrane (optional)
CMU or
reinforced-concrete
wall
(5) Weep hole
Proposed grade
sloped to drain
per precise civil
drawings
Footing and wall
design by others ^^^^
Structural footing or
settlement-sensitive improvement
Provide surface drainage via engineered
(see civil plan details)
Native backfill
1:1 (h:v) or flatter
backcut to be
properly benched
(6) 1 cubic foot of
%-inch crushed rock
(7) Footing
(1) Waterproofing membrane (optional): Liquid boot or approved mastic equivalent.
(2) Drain: Miradrain 6000 or J-drain 200 or equivalent for non-waterproofed walls: Miradrain
6200 or J-draIn 200 or equivalent for waterproofed walls (all perforations down).
(3) Filter fabric: Mirafi 140N or approved equivalent; place fabric flap behind core.
(4) Pipe: 4-lnch-dlameter perforated PVC, Schedule 40, or approved alternative with
minimum of 1 percent gradient to proper outlet point (perforations down).
(5) Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed
3 Inches above finished surface. Design civil engineer to provide drainage at toe of wall.
No weep holes for below-grade walls.
(6) Gravel: Clean, crushed, % to 1)2 Inch.
(7) Footing: If bench is created behind the footing greater than the footing width, use
level fill or cut natural earth materials. An additional "heel" drain will likely be required by
geotechnical consultant.
RETAINING WALL DETAIL - ALTERNATIVE B Detail 2
(1) Waterproofing
membrane
CMU or
reinforced-concrete
wall
Structural footing or
settlement-sensitive improvement
Provide surface drainage
slope
t12 Inches
(5) Weep hole r Proposed grade
sloped to drain
per precise civil
drawings
Footing and wall
design by others
(8) Native backfill
(6) Clean
sand backfill
1:1 (h:v) or flatter
backcut to be
properly benched (3) Filter fabric
(2) Gravel
(4) Pipe
— (7) Footing
(1) Waterproofing membrane: Liquid boot or approved masticequivalent.
(2) Gravel: Clean, crushed, % to 1)^ inch.
(3) Filter fabric: Mirafi MON or approved equivalent.
(4) Pipe: 4-inch-dlameter perforated PVC, Schedule 40, or approved alternative with minimum
of 1 percent gradient to proper outlet point (perforations down).
(5) Weep hole: Minimum 2-Inch diameter placed at 20-foot centers along the wall and placed
3 Inches above finished surface. Design civil engineer to provide drainage at toe of wall.
No weep holes for below-grade walls.
(6) Clean sand backfill: Must have sand equivalent value (S.E.) of 35 or greater; can be
densified by water jetting upon approval by geotechnical engineer.
(7) Footing: If bench is created behind the footing greater than the footing width, use
level fill or cut natural earth materials. An additional "heel" drain will likely be required by
geotechnical consultant.
(8) Native backfill: If E.I. <21 and S.E. >35 then all sand requirements also may not be required
and will be reviewed by the geotechnical consultant.
RETAINING WALL DETAIL - ALTERNATIVE C Detail 3
c) Embed the footings entirely into native formational material (i.e., deepened
footings).
If transitions from cut to fill transect the wall footing alignment at an angle of less than
45 degrees (plan view), then the designer should follow recommendation "a" (above) and
until such transition is between 45 and 90 degrees to the wall alignment.
TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS AND EXPANSIVE SOILS
Expansive Soils and Slope Creep
Some of the onsite soils may be expansive. Expansive soils become desiccated when
allowed to dn/. Such soils are susceptible to surficial slope creep, especially with seasonal
changes in moisture content. Typically in southern California, during the hot and dry
summer period, these soils become desiccated and shrink, thereby developing surface
cracks. The extent and depth ofthese shrinkage cracks depend on many factors such as
the nature and expansivity of the soils, temperature and humidity, and extraction of
moisture from surface soils by plants and roots. When seasonal rains occur, water
percolates into the cracks and fissures, causing slope surfaces to expand, with a
corresponding loss in soil density and shear strength near the slope surface. With the
passage of time and several moisture cycles, the outer 3 to 5 feet of slope materials
experience a very slow, but progressive, outward and downward movement, known as
slope creep. For slope heights greater than 10 feet, this creep related soil movement will
typically impact all rear yard flatwork and other secondary improvements that are located
within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork,
etc., and in particular top of slope fences/walls. This influence is normally in the form of
detrimental settlement, and tilting ofthe proposed improvements. The dessication/swelling
and creep discussed above continues over the life of the improvements, and generally
becomes progressively worse. Accordingly, the developer should provide this information
to all interested/affected parties.
Top of Slope Walls/Fences
Due to the potential for slope creep for slopes higher than about 10 feet, some settlement
and tilting of the walls/fence with the corresponding distress, should be expected. To
mitigate the tilting of top of slope walls/fences, we recommend that the walls/fences be
constructed on a combination of grade beam and drilled pier foundations. The grade
beam should be at a mininnum of 12 inches by 12 inches in cross section, supported by
drilled caissons, 12 inches minimum in diameter, placed at a maximum spacing of 6 feet
on center, and with a minimum embedment length of 7 feet below the bottom ofthe grade
beam. Drilled piers/grade beams should not disrupt any geogrid reinforcements. The
strength of the concrete and grout should be evaluated by the structural engineer of
record. The proper ASTM tests for the concrete and mortar should be provided along with
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the slump quantities. The concrete used should be appropriate to mitigate sulfate
corrosion, as warranted. The design ofthe grade beam and piers should be in accordance
with the recommendations ofthe project structural engineer, and include the utilization of
the following geotechnical parameters:
Creep Zone:
Creep Load:
Point of Fixity:
Passive Resistance:
5-footvertical zone belowthe slope face and projected upward
parallel to the slope face.
The creep load projected on the area of the grade beam
should be taken as an equivalent fluid approach, having a
density of 60 pcf. For the pier, it should be taken as a uniform
900 pounds per linear foot of pier's depth, located above the
creep zone.
Located a distance of 1 to 1.5 times the pier's diameter, below
the creep zone or below the formational contact.
Passive earth pressure of 250 psf per foot of depth per foot of
pier diameter, to a maximum value of 2,500 psf may be used
to determine caisson depth and spacing, provided that they
meet or exceed the minimum requirements stated above. To
determine the total lateral resistance, the contribution of the
creep prone zone above the point of fixity, to passive
resistance, should be disregarded.
Allowable Axial Capacitv:
Shaft capacity:
Tip capacity:
300 psf applied below the point of fixity over the surtace area
of the shaft in approved compacted fill (min. 90% relative
compaction) or formational materials.
3,000 psf in approved compacted fill (min. 90% relative
compaction) or formational materials. This assumes the
absence of water in the drilled shafts and the bottom of the
drilled shaft will be free of all loose soils or debris.
EXPANSIVE SOILS, DRIVEWAY. FLATWORK. AND OTHER IMPROVEMENTS
Some of the onsite soils may be expansive. The effects of expansive soils are cumulative,
and typically occur over the lifetime of any improvements. On relatively level areas, when
the soils are allowed to dry, the dessication and swelling process tends to cause heaving
and distress to flatwork and other improvements. The resulting potential for distress to
improvements may be reduced, but not totally eliminated. To that end, it is recommended
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thatthe developer should notify all interested/affected parties ofthis long-term potential for
distress. To reduce the likelihood of distress, the following recommendations are
presented for all exterior flatwork:
1. The subgrade area for concrete slabs should be compacted to achieve a minimum
90 percent relative compaction, and then be presoaked to 2 to 3 percentage points
above (or 125 percent of) the soils' optimum moisture content, to a depth of
18 inches below subgrade elevation. The moisture content of the subgrade should
be proof tested within 72 hours prior to pouring concrete.
2. Concrete slabs should be cast over a relatively non-yielding surface, consisting of
a 4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and
level prior to pouring concrete. The layer should wet-down completely prior to
pouring concrete, to minimize loss of concrete moisture to the surrounding earth
materials. If subgrade soils are very low expansive, the gravel layer may be omitted.
3. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and
approaches should additionally have a thickened edge (8 inches) adjacent to all
landscape areas, to help impede infiltration of landscape water under the slab.
4. The use of transverse and longitudinal control joints are recommended to help
control slab cracking due to concrete shrinkage or expansion. Two ways to
mitigate such cracking are: a) add a sufficient amount of reinforcing steel,
increasing tensile strength of the slab; and, b) provide an adequate amount of
control and/or expansion joints to accommodate anticipated concrete shrinkage
and expansion.
In order to reduce the potential for unsightly cracks, slabs should be reinforced at
mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each
direction. The exterior slabs should be scored or saw cut, 72 to % inches deep,
often enough so that no section is greater than 10 feet by 10 feet. For sidewalks or
narrow slabs, control joints should be provided at intervals of every 6 feet. The
slabs should be separated from the foundations and sidewalks with expansion joint
filler material.
5. No traffic should be allowed upon the newly poured concrete slabs until they have
been properiy cured to within 75 percent of design strength. Concrete compression
strength should be a minimum of 2,500 psi.
6. Driveways, sidewalks, and patio slabs adjacent to the residential structures should
be separated from the residences with thick expansion joint filler material. In areas
directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.),
all joints should be additionally sealed with flexible mastic.
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7. Planters and walls should not be tied to the residential structures.
8. Overhang structures should be supported on the slabs, or structurally designed
with continuous footings tied in at least two directions.
9. Any masonry landscape walls that are to be constructed throughout the property
should be grouted and articulated in segments no more than 20 feet long. These
segments should be keyed or doweled together.
10. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible
connections to accommodate differential settlement and expansive soil conditions.
11. Positive site drainage should be maintained at all times. Finish grade on the lots
should provide a minimum of 1 to 2 percent fall to the street, as indicated herein.
It should be kept in mind that drainage reversals could occur, including
post-construction settlement, if relatively flat yard drainage gradients are not
periodically maintained by the homeowner or homeowners association.
12. Due to expansive soils, air conditioning (A/C) units should be supported by slabs
that are incorporated into the building foundation or constructed on a rigid slab with
flexible couplings for plumbing and electrical lines. /VC waste water lines should
be drained to a suitable non-erosive outlet.
13. Shrinkage cracks could become excessive if proper finishing and curing practices
are not followed. Finishing and curing practices should be performed per the
Portland Cement Association Guidelines. Mix design should incorporate rate of
curing for climate and time of year, sulfate content of soils, corrosion potential of
soils, and fertilizers used on site.
PRELIMINARY PAVEMENT DESIGN/CONSTRUCTION
Structural Section
Traffic Index (Tl) values were assumed to range between 4.5 and 5.0 for the private
roadway, and should be reviewed by the project civil engineer for comment, and any
revisions, as necessary. An R-value of 20 was assumed for preliminary planning purposes
in this study. The recommended preliminary pavement sections for both asphaltic
concrete (A.C.) pavement over aggregate base (A.B.) and Portland Cement Concrete
Pavement (P.C.C.P.) in the following tables:
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APPROXIMATE. .
'.TRAFFIC AREA ,
TRAFFIC
'INDEX<^>
.^y^iGrRADE
'.hrvALQEi^
A.c.
THiqKNESS
(TNCHES)
A.B.
,'THICKNESS°>
'(INCH^)
Private Street 4.5 20 4.0 <"> 4.0 <^>
Private Street 5.0 20 4.0 6.0
'^'ihe Tl is assumed based on the intended use and review of City of Carlsbad (2004). The Tl should be
reviewed revised as necessary by the project civil engineer. Trash disposal areas, entry areas, fire vehicle
access may require special design and/or detailing.
Estimate, to be verified during grading and prior to placement of the street section.
Denotes Class 2 Aggregate Base R >_78, SE >.25).
City minimum.
P0RTLA^ D CONCRETE CEMENT PAVEMENTS (PCCP)
TRAFFIC
AREAS
1
(toNCRETE
TYPE
PCCP
THICKNESS
(INCHES) •
TRAFFIC
AREAS
CONCIREfE'
\ fYP|"|.P
n ' PCCP
THICKNESS
(INCHES)
Ught Vehicles
520-C-2500 6.0
Heavy Truck Traffic
520-C-2500 8.0
Ught Vehicles
560-C-3250 5.0
Heavy Truck Traffic
560-C-3250 7.0
NOTE: All PCCP is designed as un-reinforced and bearing directly on compacted subgrade. However, a 4-inch thick
leveling course of compacted aggregate base, or crushed rock may be considered to improve performance. All PCCP
should be properly detailed (jointing, etc.) perthe industry standard. Pavements may be additionally reinforced with
#4 reinforcing bars, placed 12 inches on center, each way, for improved performance. Trash truck loading pads shall
be 8 inches per the City standard and reinforced accordingly.
All pavement installation, including preparation and compaction of subgrade, compaction
of base material, and placement and rolling of asphaltic concrete, etc., shall be done in
accordance with the City of Carisbad guidelines, and underthe observation and testing of
the project geotechnical engineer and/or the City.
The recommended pavement sections are meant as minimums. If thinner or highly
variable pavement sections are constructed, increased maintenance and repair may be
needed. The recommended pavement sections provided above are intended as a
minimum guideline. If thinner or highly variable pavement sections are constructed,
increased maintenance and repair could be expected. Ifthe ADT (average daily traffic) or
ADTT (average daily truck traffic) increases beyond that intended, as reflected by the Tl
used for design, increased maintenance and repair could be required for the pavement
section. Consideration should be given to the increased potential for distress from overuse
of paved street areas by heavy equipment and/or construction related heavy traffic
(e.g., concrete trucks, loaded supply trucks, etc.), particularty when thefinal section is not
in place (i.e., topcoat). Best management construction practices should be followed atall
times, especially during inclement weather.
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PAVEMENT GRADING RECOMMENDATIONS
General
All section changes should be property transitioned. If adverse conditions are encountered
during the preparation of subgrade materials, special construction methods may need to
be employed. A GSI representative should be present for the preparation of subgrade,
aggregate base, and asphaltic concrete.
Subgrade
Within street and parking areas, all surficial deposits of loose soil material should be
removed and recompacted as recommended. After the loose soils are removed, the
bottom is to be scarified to a depth of at least 6 inches, moisture conditioned as necessary
and compacted to 95 percent of the maximum laboratory density, as determined by
ASTM D 1557.
Deleterious material, excessively wet ordry pockets, concentrated zones of oversized rock
fragments, and any other unsuitable materials encountered during grading should be
removed. The compacted fill material should then be brought to the elevation of the
proposed subgrade for the pavement. The subgrade should be proof-rolled in order to
promote a uniform firm and unyielding surface. All grading and fill placement should be
observed bythe project geotechnical consultant.
Aggregate Base
Compaction tests are required forthe recommended aggregate base section. Minimum
relative compaction required will be 95 percent of the laboratory maximum density as
determined by ASTM D 1557. Base aggregate should be in accordance to the
"Greenbook" crushed aggregate base rock (minimum R-value=78).
Paving
Prime coat may be omitted if all of the following conditions are met:
1. The asphalt pavement layer is placed within two weeks of completion of aggregate
base and/or sub base course.
2. Traffic is not routed over completed base before paving
3. Construction is completed during the dry season of May through October.
4. The aggregate base is kept free of debris prior to placement of asphaltic concrete.
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If construction is performed during the wet season of November through April, prime coat
may be omitted if no rain occurs between completion ofthe aggregate base course and
paving and the time between completion of aggregate base and paving is reduced to three
days, provided the aggregate base is free of loose soil or debris. Where prime coat has
been omitted and rain occurs, traffic is routed overthe aggregate base course, or paving
is delayed, measures shall be taken to restore the aggregate base course, and subgrade
to conditions that will meet specifications as directed bythe geotechnical consultant. GSI
has assumed that traffic will not be allowed on recently placed AC for a period of 24 hours
or more.
Drainage
Positive drainage should be provided for all surface water to drain towards the area swale,
curb and gutter, or to an approved drainage channel. Positive site drainage should be
maintained at all times. Water should not be allowed to pond or seep into the ground,
such as from behind unprotected curbs, both during and after grading. If planters or
landscaping are adjacent to paved areas, measures should be taken to minimize the
potential for water to enter the pavement section, such as thickened edges, enclosed
planters, etc. Also, best management construction practices should be strictly adhered to
at all times to minimize the potential for distress during construction and roadway
improvements. Seismic effects may reverse relatively flat gradients in streets and gutters.
These should be periodically checked following a significant seismic event.
PCC Cross Gutters
PCC cross gutters should be designed in accordance with San Diego Regional Standard
Drawing (SDRSD) G-12.
Additional Considerations
To mitigate perched groundwater, consideration should be given to installation of
subgrade separators (cut-offs) between pavement subgrade and landscape areas,
although this is not a requirement from a geotechnical standpoint. Cut-offs, if used, should
be 6 inches wide and at least 12 inches below the pavement subgrade contact or
12 inches below the crushed aggregate base rock, if utilized.
ONSITE INFILTRATION-RUNOFF RETENTION SYSTEMS
General
Should onsite infiltration-runoff retention systems (OIRRS) be planned for Best
Management Practices (BMP's) or Low Impact Development (LID) principles for the
project, some guidelines should/must be followed in the planning, design, and
construction of such systems. Such facilities, if improperiy designed or implemented
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without consideration of the geotechnical aspects of site conditions, can contribute to
flooding, saturation of bearing materials beneath site improvements, slope instability, and
possible concentration and contribution of pollutants into the groundwater or storm drain
and/or utility trench systems.
A key factor in these systems is the infiltration rate (often referred to as the percolation rate)
which can be ascribed to, or determined for, the earth materials within which these
systems are installed. Additionally, the infiltration rate ofthe designed system (which may
include gravel, sand, mulch/topsoil, or other amendments, etc.) will need to be considered.
The project infiltration testing is very site specific, any changes to the location of the
proposed OIRRS and/or estimated size of the OIRRS, may require additional infiltration
testing. Locally, relatively impermeable formations include: terrace deposits, claystone,
siltstone, cemented sandstone, igneous and metamorphic bedrock, as well as expansive
fill soils.
Some ofthe methods which are utilized for onsite infiltration include percolation basins,
drywells, bio-swale/bio-retention, permeable pavers/pavement, infiltration trenches, filter
boxes and subsurface infiltration galleries/chambers. Some of these systems are
constructed using native and import soils, perforated piping, and filter fabrics while others
employ structural components such as stormwater infiltration chambers and
filters/separators. Every site will have characteristics which should lend themselves to one
or more ofthese methods; but, not every site is suitable for OIRRS. In practice, OIRRS are
usually initially designed by the project design civil engineer. Selection of methods should
include (but should not be limited to) review by licensed professionals including the
geotechnical engineer, hydrogeologist, engineering geologist, project civil engineer,
landscape architect, environmental professional, and industrial hygienist. Applicable
governing agency requirements should be reviewed and included in design
considerations.
The following geotechnical guidelines should be considered when designing onsite
infiltration-runoff retention systems:
• Based on our review of the United States Department of Agriculture Soil Survey
(http://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx),the onsite soils
fall into Hydrologic Soil Groups (HSG) "B" and "D" as defined in County of
San Diego (2007a). Based on the indurated nature of the formational earth
materials, the onsite soils are likely more aligned with HSG "D" on a preliminary
basis.
• It is not good engineering practice to allow water to saturate soils, especially near
slopes or improvements; however, the controlling agency/authority is now requiring
this for OIRRS purposes on many projects.
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• If infiltration is planned, infiltration system design should be based on actual
infiltration testing results/data, preferably utilizing double-ring infiltrometer testing
(ASTM D 3385) to determine the infiltration rate of the earth materials being
contemplated for infiltration.
• Wherever possible, infiltration systems should not be installed within ±50 feet ofthe
tops of slopes steeper than 15 percent or within H/3 from the tops of slopes (where
H equals the height of slope).
• Wherever possible, infiltrations systems should not be placed within a distance of
H/2 from the toes of slopes (where H equals the height of slope).
The landscape architect should be notified of the location of the proposed OIRRS.
If landscaping is proposed within the OIRRS, consideration should be given to the
type of vegetation chosen and their potential effect upon subsurface improvements
(i.e., some trees/shrubs will have an effect on subsurface improvements with their
extensive root systems). Over-watering landscape areas above, or adjacent to, the
proposed OIRRS could adversely affect performance ofthe system.
• Areas adjacent to, or within, the OIRRS that are subject to inundation should be
properiy protected against scouring, undermining, and erosion, in accordance with
the recommendations ofthe design engineer.
• Seismic shaking may result in the formation of a seiche which could potential
overtop the banks of an OIRRS and result in down-gradient flooding and scour.
• If subsurface infiltration galleries/chambers are proposed, the appropriate size,
depth interval, and ultimate placement ofthe detention/infiltration system should be
evaluated by the design engineer, and be of sufficient width/depth to achieve
optimum performance, based on the infiltration rates provided. In addition, proper
debris filter systems will need to be utilized for the infiltration galleries/chambers.
Debris filter systems will need to be self cleaning and periodically and regulariy
maintained on a regular basis. Provisions for the regular and periodic maintenance
of any debris filter system is recommended and this condition should be disclosed
to all interested/affected parties.
• Infiltrations systems should not be installed within ±8 feet of building foundations
utility trenches, and walls, or a 1:1 (horizontal to vertical [h:v]) slope (down and
away) from the bottom elements ofthese improvements. Alternatively, deepened
foundations and/or pile/pier supported improvements may be used.
• Infiltrations systems should not be installed adjacent to pavement and/or hardscape
improvements. Alternatively, deepened/thickened edges and curbs and/or
impermeable liners may be utilized in areas adjoining the OIRRS.
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• As with any OIRRS, localized ponding and groundwater seepage should be
anticipated. The potential for seepage and/or perched groundwater to occur after
site development should be disclosed to all interested/affected parties.
• Installation of infiltrations systems should avoid expansive soils (E.I. >51) or soils
with a relatively high plasticity index (P.l. > 20).
• Infiltration systems should not be installed where the vertical separation of the
groundwater level is less than ±10 feet from the base ofthe system.
• Where permeable pavements are planned as part of the system, the site Traffic
Index (T.l.) should be less than 25,000 Average Daily Traffic (ADT), as
recommended in Allen, et al. (2011).
• Infiltration systems should be designed using a suitable factor-of-safety (FOS) to
account for uncertainties in the known infiltration rates (as generally required bythe
controlling authorities), and reduction in performance overtime.
• As with any OIRRS, proper care will need to provided. Best management practices
should be followed at all times, especially during inclement weather. Provisions for
the management of any siltation, debris within the OIRRS, and/or overgrown
vegetation (including root systems) should be considered. An appropriate
inspection schedule will need to adopted and provided to all interested/affected
parties.
• Any designed system will require regular and periodic maintenance, which may
include rehabilitation and/or complete replacement ofthe filter media (e.g., sand,
gravel, filter fabrics, topsoils, mulch, etc.) or other components utilized in
construction, so that the design life exceeds 15 years. Due to the potential for
piping and adverse seepage conditions, a burrowing rodent control program should
also be implemented onsite.
• All or portions of these systems may be considered attractive nuisances. Thus,
consideration ofthe effects of, or potential for, vandalism should be addressed.
• Newly established vegetation/landscaping (including phreatophytes) may have root
systems that will influence the performance ofthe OIRRS or nearby LID systems.
• The potential for surface flooding, in the case of system blockage, should be
evaluated by the design engineer.
• Any proposed utility backfill materials (i.e., inlet/outlet piping and/or other
subsurface utilities) located within or near the proposed area of the OIRRS may
become saturated. This is due to the potential for piping, water migration, and/or
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seepage along the utility trench line backfill. If utility trenches cross and/or are
proposed near the OIRRS, cut-off walls or other water barriers will need to be
installed to mitigate the potential for piping and excess water entering the utility
backfill materials. Planned or existing utilities may also be subject to piping of fines
into open-graded gravel backfill layers unless separated from overlying or adjoining
OIRRS by geotextiles and/or slurry backfill.
The use of OIRRS above existing utilities that might degrade/corrode with the
introduction of water/seepage should be avoided.
A vector control program may be necessary as stagnant water contained in OIRRS
may attract mammals, birds, and insects that carry pathogens.
PRELIMINARY OUTDOOR POOL/SPA DESIGN RECOMMENDATIONS
Although WE&S (2013) does not show planned swimming pools and spas, individual
property owners may include these improvements into their landscape plans. As such, the
following preliminary recommendations are provided for consideration in pool/spa design
and planning. These recommendations may need to be modified based on a review ofthe
final civil design, swimming pool/spa layout, and the as-graded conditions.
Recommendations for pools/spas and/or deck flatwork underlain by expansive soils, or for
areas with differential settlement greaterthan 74-inch over 40 feet horizontally, will be more
onerous than the preliminary recommendations presented below. The conditions and
recommendations presented herein should be disclosed to all homeowners and any
interested/affected parties.
General
1. The equivalent fluid pressure to be used for the pool/spa design should be 60 pcf
for pool/spa walls with level backfill, and 75 pcf for a 2:1 sloped backfill condition.
In addition, backdrains should be provided behind pool/spa walls subjacent to
slopes.
2. Passive earth pressure may be computed as an equivalent fluid having a density of
150 pcf, to a maximum lateral earth pressure of 1,000 psf.
3. An allowable coefficient of friction between soil and concrete of 0.30 may be used
with the dead load forces.
4. When combining passive pressure and frictional resistance, the passive pressure
component should be reduced by one-third.
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5. Where pools/spas are planned near structures, appropriate surcharge loads need
to be incorporated into design and construction by the pool/spa designer. This
includes, but is not limited to landscape berms, decorative walls, footings, built-in
barbeques, utility poles, etc.
6. All pool/spa walls should be designed as "free standing" and be capable of
supporting the water in the pool/spa without soil support. The shape of pool/spa
in cross section and plan view may affect the performance of the pool, from a
geotechnical standpoint. Pools and spas should also be designed in accordance
with Section 1808.7.3 ofthe 2013 CBC (CBSC, 2013). Minimally, the bottoms ofthe
pools/spas, should maintain a distance H/3, where H is the height ofthe slope (in
feet), from the slope face. This distance should not be less than 7 feet, nor need not
be greater than 40 feet.
7. The soil beneath the pool/spa bottom should be uniformly moist with the same
stiffness throughout. If fill/residuum or bedrock transitions occur beneath the
pool/spa bottom, the residuum or bedrock should be overexcavated to a minimum
depth of 48 inches, and replaced with compacted fill, such that there is a uniform
blanket that is a minimum of 48 inches below the pool/spa shell. If very low
expansive soil is used for fill, the fill should be placed at a minimum of 95 percent
relative compaction, at optimum moisture conditions. This requirement should be
90 percent relative compaction at over optimum moisture if the pool/spa is
constructed within or near expansive soils. The potential for grading and/or
re-grading ofthe pool/spa bottom, and attendant potential for shoring and/or slot
excavation, needs to be considered during all aspects of pool/spa planning, design,
and construction.
8. Ifthe pool/spa is founded entirely in compacted fill placed during rough grading, the
deepest portion ofthe pool/spa should correspond with the thickest fill on the lot.
9. Hydrostatic pressure relief valves should be incorporated into the pool and spa
designs. A pool/spa under-drain system is also recommended, with an appropriate
outlet for discharge.
10. All fittings and pipe joints, particularly fittings in the side of the pool or spa, should
be properiy sealed to prevent water from leaking into the adjacent soils materials,
and be fitted with slip or expandible joints between connections transecting varying
soil conditions.
11. An elastic expansion joint (flexible waterproof sealant) should be installed to prevent
water from seeping into the soil at all deck joints.
12. A reinforced grade beam should be placed around skimmer inlets to provide
support and mitigate cracking around the skimmer face.
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13. In order to reduce unsightly cracking, deck slabs should minimally be 4 inches
thick, and reinforced with No. 3 reinforcing bars at 18 inches on-center. All slab
reinforcement should be supported to ensure proper mid-slab positioning during
the placement of concrete. Wire mesh reinforcing is specifically not recommended.
Deck slabs should not be tied to the pool/spa structure. Pre-moistening and/or
pre-soaking of the slab subgrade is recommended, to a depth of 12 inches
(optimum moisture content), or 18 inches (120 percent of the soil's optimum
moisture content, or 3 percent over optimum moisture content, whichever is
greater), for very low to low, and medium expansive soils, respectively. This
moisture content should be maintained in the subgrade soils during concrete
placement to promote uniform curing of the concrete and minimize the
development of unsightly shrinkage cracks. Slab underiayment should consist of
a 1-to 2-inch leveling course of sand (S.E.>30) and a minimum of 4 to 6 inches of
Class 2 base compacted to 90 percent. Deck slabs within the H/3 zone, where H
is the height of the slope (in feet), will have an increased potential for distress
relative to other areas outside of the H/3 zone. If distress is undesirable,
improvements, deck slabs or flatwork should not be constructed closer than H/3 or
7 feet (whichever is greater) from the slope face, in order to reduce, but not
eliminate, this potential.
14. Pool/spa bottoms, deck slabs, and other associated improvements should be
founded entirely on competent residuum, tonalite bedrock, or properiy compacted
fill. Pools, spas, and associated improvements constructed within the non-structural
zone shown on Plate 1 will specifically require the use of a drilled pier and grade
beam foundations for support. Fill should be compacted to achieve a minimum
90 percent relative compaction, as discussed above. Prior to pouring concrete,
subgrade soils below the pool/spa decking should be throughly watered to achieve
a moisture content that is at least 2 percent above optimum moisture content, to a
depth of at least 18 inches below the bottom of slabs. This moisture content should
be maintained in the subgrade soils during concrete placement to promote uniform
curing ofthe concrete and minimize the development of unsightly shrinkage cracks.
15. In order to reduce unsightly cracking, the outer edges of pool/spa decking to be
bordered by landscaping, and the edges immediately adjacent to the pool/spa,
should be underlain by an 8-inch wide concrete cutoff shoulder (thickened edge)
extending to a depth ofat least 12 inches belowthe bottoms ofthe slabs to mitigate
excessive infiltration of water under the pool/spa deck. These thickened edges
should be reinforced with two No. 4 bars, one at the top and one at the bottom.
Deck slabs may be minimally reinforced with No. 3 reinforcing bars placed at
18 inches on-center, in both directions. All slab reinforcement should be supported
on chairs to ensure proper mid-slab positioning during the placement of concrete.
16. Surface and shrinkage cracking of the finish slab may be reduced if a low slump
and water-cement ratio are maintained during concrete placement. Concrete
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utilized should have a minimum compressive strength of 4,000 psi and a maximum
water to cement ratio of 0.50. Excessive water added to concrete prior to
placement is likely to cause shrinkage cracking, and should be avoided. Some
concrete shrinkage cracking, however, is unavoidable.
17. Joint and sawcut locations for the pool/spa deck should be determined by the
design engineer and/or contractor. However, spacings should not exceed 6 feet
on-center.
18. Considering the nature of the onsite earth materials, it should be anticipated that
caving or sloughing could be a factor in subsurface excavations and trenching.
Shoring or excavating the trench walls/backcuts at the angle of repose (typically 25
to 45 degrees), should be anticipated. All excavations should be observed by a
representative ofthe geotechnical consultant, including the project geologist and/or
geotechnical engineer, prior to workers entering the excavation or trench, and
minimally conform to CAL-OSHA, state, and local safety codes. Should adverse
conditions exist, appropriate recommendations should be offered atthattime bythe
geotechnical consultant. GSI does not consult in the area of safety engineering and
the safety of the construction crew is the responsibility of the pool/spa builder.
19. It is imperative that adequate provisions for surface drainage are incorporated by
the homeowners into their overall improvement scheme. Ponding water, ground
saturation and flow over slope faces, are all situations which must be avoided to
enhance longterm performance ofthe pool/spa and associated improvements, and
reduce the likelihood of distress.
20. Regardless ofthe methods employed, once the pool/spa is filled with water, should
it be emptied, there exists some potential that if emptied, significant distress may
occur. Accordingly, once filled, the pool/spa should not be emptied unless
evaluated by the geotechnical consultant and the pool/spa builder.
21. For pools/spas built within (all or part) ofthe 2013 CBC setback and/or geotechnical
setback, as indicated in the site geotechnical documents, special foundations are
recommended to mitigate the affects of creep, lateral fill extension, expansive soils
and settlement on the proposed pool/spa. Most municipalities or County reviewers
do not consider these effects in pool/spa plan approvals. As such, where
pools/spas are proposed on 20 feet or more of fill, medium or highly expansive
soils, or rock fill with limited "cap soils" and built within 2013 CBC setbacks, or
within the influence ofthe creep zone, or lateral fill extension, the following should
be considered during design and construction:
OPTION A: Shallow foundations with or without overexcavation of the
pool/spa "shell," such that the pool/spa is surrounded by 5 feet of very low
to low expansive soils (without irreducible particles greater that 6 inches).
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and the pool/spa walls closer to the slope(s) are designed to be free
standing. GSI recommends a pool/spa under-drain or blanket system (see
Typical Pool/Spa Detail [Appendix F]). The pool/spa builders and owner in
this optional construction technique should be generally satisfied with
pool/spa performance underthis scenario; however, some settlement, tilting,
cracking, and leakage of the pool/spa is likely over the life of the project.
OPTION B: Pier supported pool/spa foundations with or without
overexcavation ofthe pool/spa shell such thatthe pool/spa is surrounded by
5 feet ofvery lowto low expansive soils (without irreducible particles greater
than 6 inches), and the pool/spa walls closer to the slope(s) are designed to
be free standing. The need for a pool/spa under-drain system may be
installed for leak detection purposes. Piers that support the pool/spa should
be a minimum of 12 inches in diameter and at a spacing to provide vertical
and lateral support of the pool/spa, in accordance with the pool/spa
designers recommendations, local code, and the 2013 CBC. The pool/spa
builder and owner in this second scenario construction technique should be
more satisfied with pool/spa performance. This construction will reduce
settlement and creep effects on the pool/spa; however, it will not eliminate
these potentials, nor make the pool/spa "leak-free."
22. The temperature of the water lines for spas and pools may affect the corrosion
properties of site soils, thus, a corrosion specialist should be retained to review all
spa and pool plans, and provide mitigative recommendations, as warranted.
Concrete mix design should be reviewed by a qualified corrosion consultant and
materials engineer.
23. All pool/spa utility trenches should be compacted to 90 percent of the laboratory
standard, under the full-time observation and testing of a qualified geotechnical
consultant. Utility trench bottoms should be sloped awayfrom the primary structure
on the property (typically the residence).
24. Pool and spa utility lines should not cross the primary structure's utility lines (i.e.,
not stacked, or sharing of trenches, etc.).
25. The pool/spa or associated utilities should not intercept, interrupt, or otherwise
adversely impact any area drain, roof drain, or other drainage conveyances. If it is
necessary to modify, move, or disrupt existing area drains, subdrains, or tightiines,
then the design civil engineer should be consulted, and mitigative measures
provided. Such measures should be further reviewed and approved by the
geotechnical consultant, priorto proceeding with any further construction.
26. The geotechnical consultant should review and approve all aspects of pool/spa and
flatwork design prior to construction. A design civil engineer should review all
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aspects of such design, including drainage and setback conditions. Prior to
acceptance of the pool/spa construction, the project builder, geotechnical
consultant and civil designer should evaluate the performance of the area drains
and other site drainage pipes, following pool/spa construction.
27. All aspects of construction should be reviewed and approved by the geotechnical
consultant, including during excavation, prior to the placement of any additional fill,
prior to the placement of any reinforcement or pouring of any concrete.
28. Any changes in design or location of the pool/spa should be reviewed and
approved bythe geotechnical and design civil engineer priorto construction. Field
adjustments should not be allowed until written approval of the proposed field
changes are obtained from the geotechnical and design civil engineer.
29. Disclosure should be made to homeowners and builders, contractors, and any
interested/affected parties, that pools/spas built within about 15 feet of the top of a
slope, and/or H/3, where H is the height ofthe slope (in feet), will experience some
movement or tilting. While the pool/spa shell or coping may not necessarily crack,
the levelness of the pool/spa will likely tilt toward the slope, and may not be
esthetically pleasing. The same is true with decking, flatwork and other
improvements in this zone.
30. Failure to adhere to the above recommendations will significantly increase the
potential for distress to the pool/spa, flatwork, etc.
31. Local seismicity and/or the design earthquake will cause some distress to the
pool/spa and decking or flatwork, possibly including total functional and economic
loss.
32. The information and recommendations discussed above should be provided to any
contractors and/or subcontractors, or homeowners, interested/affected parties, etc.,
that may perform or may be affected by such work.
DEVELOPMENT CRITERIA
Slope Deformation
Compacted fill slopes designed using customary factors of safety for gross or surficial
stability and constructed in general accordance with the design specifications should be
expected to undergo some differential vertical heave or settlement in combination with
differential lateral movement in the out-of-slope direction, after grading. This
post-construction movement occurs in two forms: slope creep, and lateral fill extension
(LFE). Slope creep is caused by alternate wetting and drying ofthe fill soils which results
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in slow downslope movement. This type of movement is expected to occurthroughoutthe
life ofthe slope, and is anticipated to potentially affect improvements or structures (e.g.,
separations and/or cracking), placed near the top-of-slope, upto a maximum distance of
approximately 15 feet from the top-of-slope, depending on the slope height. This
movement generally results in rotation and differential settlement of improvements located
within the creep zone. LFE occurs due to deep wetting from irrigation and rainfall on
slopes comprised of expansive materials. Although some movement should be expected,
long-term movement from this source may be minimized, but not eliminated, by placing
the fill throughout the slope region, wet of the fill's optimum moisture content.
It is generally not practical to attempt to eliminate the effects of either slope creep or LFE.
Suitable mitigative measures to reduce the potential of lateral deformation typically include:
setback of improvements from the slope faces (per the 2013 CBC), positive structural
separations (i.e., joints) between improvements, and stiffening and deepening of
foundations. Expansion joints in walls should be placed no greater than 20 feet on-center,
and in accordance with the structural engineer's recommendations. All ofthese measures
are recommended for design of structures and improvements. The ramifications of the
above conditions, and recommendations for mitigation, should be provided to all
interested/affected parties.
Slope Maintenance and Planting
Water has been shown to weaken the inherent strength of all earth materials. Slope
stability is significantly reduced by overly wet conditions. Positive surface drainage away
from slopes should be maintained and only the amount of irrigation necessary to sustain
plant life should be provided for planted slopes. Over-watering should be avoided as it
adversely affects site improvements, and causes perched groundwater conditions. Graded
slopes constructed utilizing onsite materials would be erosive. Eroded debris may be
minimized and surficial slope stability enhanced by establishing and maintaining a suitable
vegetation cover soon after construction. Compaction to the face of fill slopes would tend
to minimize short-term erosion until vegetation is established. Plants selected for
landscaping fills and fill slopes should be light weight, deep rooted types that require little
water and are capable of surviving the prevailing climate. Jute-type matting or other
fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing
plants other than those recommended above will increase the potential for perched water,
staining, mold, etc., to develop. A rodent control program to prevent burrowing should be
implemented. Irrigation of natural (ungraded) slope areas is generally not recommended.
These recommendations regarding plant type, irrigation practices, and rodent control
should be provided to all interested/affected parties. Over-steepening of slopes should be
avoided during building construction activities and landscaping.
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Drainage
Adequate surface drainage is a very important factor in reducing the likelihood of adverse
performance of foundations, hardscape, and slopes. Surface drainage should be sufficient
to mitigate ponding of water anywhere on the property, and especially near structures and
tops of slopes. Surface drainage should be carefully taken into consideration during fine
grading, landscaping, and building construction. Therefore, care should be taken that
future landscaping or construction activities do not create adverse drainage conditions.
Positive site drainage within the property should be provided and maintained at all times.
Drainage should not flow uncontrolled down any descending slope. Water should be
directed awayfrom foundations and tops of slopes, and not allowed to pond and/or seep
into the ground. In general, site drainage should conform to Section 1804.3 of the
2013 CBC. Consideration should be given to avoiding construction of planters adjacent
to structures (buildings, pools, spas, etc.). Building pad drainage should be directed
toward the street or other approved area(s). Although not a geotechnical requirement, roof
gutters, down spouts, or other appropriate means may be utilized to control roof drainage.
Down spouts, or drainage devices should outlet a minimum of 5 feet from structures or into
a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy
rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas
of seepage develop, recommendations for minimizing this effect could be provided upon
request. Seismic effects may reverse or redirect surface drainage along relatively flat
gradients. Surface drainage should be periodically checked following a significant seismic
event.
Erosion Control
Natural and fill slopes will be subject to surficial erosion during and after grading. Onsite
soils have a moderate to high erosion potential. Consideration should be given to
providing hay bales and silt fences forthe temporary control of surface water for such soils,
from a geotechnical viewpoint. Thus, properiy designed site drainage is necessary in
reducing erosion damage to the planned improvements.
Landscape Maintenance
Only the amount of irrigation necessary to sustain plant life should be provided.
Over-watering the landscape areas will adversely affect proposed site improvements. We
would recommend that any proposed open-bottom planters adjacent to proposed
residential structures be eliminated for a minimum distance of 10 feet. As an alternative,
closed-bottom type planters could be utilized. An outlet placed in the bottom of the
planter, could be installed to direct drainage awayfrom structures or any exterior concrete
flatwork. If planters are constructed adjacent to structures, the sides and bottom of the
planter should be provided with a moisture barrierto prevent penetration of irrigation water
into the subgrade. Provisions should be made to drain the excess irrigation water from the
planters without saturating the subgrade below or adjacent to the planters. Graded slope
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areas should be planted with drought resistant vegetation. Consideration should be given
to the type of vegetation chosen and their potential effect upon surface improvements (i.e.,
some trees will have an effect on concrete flatwork with their extensive root systems).
From a geotechnical standpoint leaching is not recommended for establishing
landscaping. If the surface soils are processed for the purpose of adding amendments,
they should be recompacted to 90 percent minimum relative compaction.
Gutters and Downspouts
As previously discussed in the drainage section, the installation of gutters and downspouts
should be considered to collect roof water that may otherwise infiltrate the soils adjacent
to the residential structures. If utilized, the downspouts should be drained into PVC
collector pipes or other non-erosive devices (e.g., paved swales or ditches; below grade,
solid tight-lined PVC pipes; etc.), that will carry the water away from the house, to an
appropriate outlet, in accordance with the recommendations ofthe design civil engineer.
Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint,
provided that positive drainage is incorporated into project design (as discussed
previously).
Subsurface and Surface Water
Subsurface and surface water are not anticipated to affect site development, provided that
the recommendations contained in this report are incorporated into final design and
construction and that prudent surface and subsurface drainage practices are incorporated
into the construction plans. Perched groundwater conditions along zones of contrasting
permeabilities may not be precluded from occurring in the future dueto site irrigation, poor
drainage conditions, or damaged utilities, and should be anticipated. Should perched
groundwater conditions develop, this office could assess the affected area(s) and provide
the appropriate recommendations to mitigate the observed groundwater conditions.
Groundwater conditions may change with the introduction of irrigation, rainfall, or other
factors.
Site Improvements
If in the future, any additional improvements (e.g., pools, spas, etc.) are planned forthe
site, recommendations concerning the geological or geotechnical aspects of design and
construction of said improvements could be provided upon request. Pools and/or spas
should not be constructed without specific design and construction recommendations from
GSI, and this construction recommendation should be provided to all interested/affected
parties. This office should be notified in advance of any fill placement, grading ofthe site,
or trench backfilling after rough grading has been completed. This includes any grading,
utility trench and retaining wall backfills, flatwork, etc.
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Tile Flooring
Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small
cracks in a conventional slab may not be significant. Therefore, the designer should
consider additional steel reinforcement for concrete slabs-on-grade where tile will be
placed. The tile installer should consider installation methods that reduce possible
cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane
(approved by the Tile Council of America/Ceramic Tile Institute) are recommended
between tile and concrete slabs on grade.
Additional Grading
This office should be notified in advance of any fill placement, supplemental regrading of
the site, or trench backfilling after rough grading has been completed. This includes
completion of grading in the street, driveway approaches, driveways, parking areas, and
utility trench and retaining wall backfills.
Footing Trench Excavation
All footing excavations should be observed by a representative ofthis firm subsequent to
trenching and prior to concrete form and reinforcement placement. The purpose of the
observations is to evaluate that the excavations have been made into the recommended
bearing material and to the minimum widths and depths recommended for construction.
If loose or compressible materials are exposed within the footing excavation, a deeper
footing or removal and recompaction ofthe subgrade materials would be recommended
at that time. Footing trench spoil and any excess soils generated from utility trench
excavations should be compacted to a minimum relative compaction of 90 percent, if not
removed from the site.
Trenching/Temporarv Construction Backcuts
Considering the nature ofthe onsite earth materials, it should be anticipated that caving
or sloughing could be a factor in subsurface excavations and trenching. Shoring or
excavating the trench walls/backcuts at the angle of repose (typically 25 to 45 degrees
[except as specifically superceded within the text ofthis report]), should be anticipated.
AN excavations should be observed by an engineering geologist or soil engineer from GSI,
prior to workers entering the excavation or trench, and minimally conform to CAL-OSHA,
state, and local safety codes. Should adverse conditions exist, appropriate
recommendations would be offered at that time. The above recommendations should be
provided to any contractors and/or subcontractors, or homeowners, etc., that may perform
such work.
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utilitv Trench Backfill
1. All interior utility trench backfill should be brought to at least 2 percent above
optimum moisture content and then compacted to obtain a minimum relative
compaction of 90 percent ofthe laboratory standard. As an alternative for shallow
(12-inch to 18-inch) under-slab trenches, sand having a sand equivalent value of
30 or greater may be utilized and jetted or flooded into place. Observation, probing
and testing should be provided to evaluate the desired results.
2. Exterior trenches adjacent to, and within areas extending below a 1:1 plane
projected from the outside bottom edge of the footing, and all trenches beneath
hardscape features and in slopes, should be compacted to at least 90 percent of
the laboratory standard. Sand backfill, unless excavated from the trench, should
not be used in these backfill areas. Compaction testing and observations, along
with probing, should be accomplished to evaluate the desired results.
3. All trench excavations should conform to CAL-OSHA, state, and local safety codes.
4. Utilities crossing grade beams, perimeter beams, or footings should either pass
below the footing or grade beam utilizing a hardened collar or foam spacer, or pass
through the footing or grade beam in accordance with the recommendations ofthe
structural engineer.
SUMMARY OF RECOMMENDATIONS REGARDING
GEOTECHNICAL OBSERVATION AND TESTING
We recommend that observation and/or testing be performed by GSI at each of the
following construction stages:
During grading/recertification.
• During excavation.
During placement of subdrains or other subdrainage devices, prior to placing fill
and/or backfill.
After excavation of building footings, retaining wall footings, and free standing walls
footings, prior to the placement of reinforcing steel or concrete.
• Prior to pouring any slabs or flatwork, after presoaking/presaturation of building
pads and other flatwork subgrade, before the placement of concrete, reinforcing
steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor retarders (i.e., visqueen,
etc.).
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During retaining wall subdrain installation, priorto backfill placement.
During placement of backfill for area drain, interior plumbing, utility line trenches,
and retaining wall backfill.
During slope construction/repair.
When any unusual soil conditions are encountered during any construction
operations, subsequent to the issuance of this report.
When any developer or homeowner improvements, such as flatwork, spas, pools,
walls, etc., are constructed, priorto construction.
A report of geotechnical observation and testing should be provided at the
conclusion of each of the above stages, in order to provide concise and clear
documentation of site work, and/or to comply with code requirements.
OTHER DESIGN PROFESSIONALS/CONSULTANTS
The design civil engineer, structural engineer, post-tension designer, architect, landscape
architect, wall designer, etc., should review the recommendations provided herein,
incorporate those recommendations into all their respective plans, and by explicit
reference, make this report part of their project plans. This report presents minimum
design criteria for the design of slabs, foundations and other elements possibly applicable
to the project. These criteria should not be considered as substitutes for actual designs
by the structural engineer/designer. Please note that the recommendations contained
herein are not intended to preclude the transmission of water or vapor through the slab or
foundation. The structural engineer/foundation and/or slab designer should provide
recommendations to not allow water or vapor to enter into the structure so as to cause
damage to another building component, or so as to limit the installation of the type of
flooring materials typically used forthe particular application.
The structural engineer/designer should analyze actual soil-structure interaction and
consider, as needed, bearing, expansive soil influence, and strength, stiffness and
deflections in the various slab, foundation, and other elements in order to develop
appropriate, design-specific details. As conditions dictate, it is possible that other
influences will also have to be considered. The structural engineer/designer should
consider all applicable codes and authoritative sources where needed. If analyses by the
structural engineer/designer result in less critical details than are provided herein as
minimums, the minimums presented herein should be adopted. It is considered likely that
some, more restrictive details will be required.
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Ifthe structural engineer/designer has any questions or requires further assistance, they
should not hesitate to call or othenwise transmit their requests to GSI. In order to mitigate
potential distress, the foundation and/or improvement's designer should confirm to GSI
and the governing agency, in writing, that the proposed foundations and/or improvements
can tolerate the amount of differential settlement and/or expansion characteristics and
other design criteria specified herein.
PLAN REVIEW
Final project plans (grading, precise grading, foundation, retaining wall, landscaping, etc.),
should be reviewed by this office prior to construction, so that construction is in
accordance with the conclusions and recommendations of this report. Based on our
review, supplemental recommendations and/or further geotechnical studies may be
warranted.
LIMITATIONS
The materials encountered on the project site and utilized for our analysis are believed
representative ofthe area; however, soil and bedrock materials vary in character between
excavations and natural outcrops or conditions exposed during mass grading. Site
conditions may vary due to seasonal changes or other factors.
Inasmuch as our study is based upon our review and engineering analyses and laboratory
data, the conclusions and recommendations are professional opinions. These opinions
have been derived in accordance with current standards of practice, and no warranty,
either express or implied, is given. Standards of practice are subject to change with time.
GSI assumes no responsibility or liability for work or testing performed by others, or their
inaction; or work performed when GSI is not requested to be onsite, to evaluate if our
recommendations have been property implemented. Use of this report constitutes an
agreement and consent by the user to all the limitations outlined above, notwithstanding
any other agreements that may be in place. In addition, this report may be subject to
review by the controlling authorities. Thus, this report brings to completion our scope of
services for this portion of the project.
The Kevane Company, Inc. W.O. 6653-A-SC
APNs 167-230-24 &-25 . Revised April 22, 2014
Fil8:e:\wp12\6600\6635a.ruge GeoSoilS, InC. Page 60
The opportunity to be of service is greatly appreciated. If you have any questions
concerning this report, or if we may be of further assistance, please do not hesitate to
contact any of the undersigned.
Respectfully submitted,
GeoSoils, Inc.
an B. BoehmeT
Project Geologist
Andrew T. Guatelli
Geotechnical Engineer, GE 2320
John P. Franklin
Engineering Geologist, CEG 1340
RBB/ATG/JPF/jh
Attachments:
Distribution:
Appendix A - References
Appendix B - Test Pit Logs
Appendix C - Seismicity Data
Appendix D - Laboratory Data
Appendix E - Slope Stability Analyses
Appendix F - General Earthwork and Grading Guidelines
Plate 1 - Geotechnical Map
Plate 2 - Geologic Cross Sections A-A' and B-B'
(1) Addressee
(2) Walsh Engineering & Surveying, Inc.
Attn: Mr. Larry Walsh (wet signed)
The Kevane Company, Inc.
APNs 167-230-24 & -25
Fil8:e:\wp12\6600\6635a.ruge GeoSoils, Inc.
w.o. 6653-A-SC
Revised April 22, 2014
Page 61
APPENDIXA
REFERENCES
GeoSoils, Inc.
APPENDIXA
REFERENCES
Allen, v., Connerton, A., and Carison, C, 2011, Introduction to Infiltration Best
Management Practices (BMP), Contech Construction Products, Inc., Professional
Development Series, dated December.
American Concrete Institute, 2004, Guide for concrete floor and slab construction:
reported by ACI Committee 302; Designation ACI 302.1 R-04, dated March 23.
American Concrete Institute, 2011, Building code requirements for structural concrete (ACI
318-11), an ACI sta ndard and commentary: reported by ACI Committee 318; dated
May 24.
American Concrete Institute Committee 360, 2006, Design of slabs-on-ground
(ACI 360R-06).
American Concrete Institute Committee 302, 2004, Guide for concrete floor and slab
construction, ACI 302.1 R-04, dated June.
American Concrete Institute Committee on Responsibility in Concrete Construction, 1995,
Guidelines for authorities and responsibilities in concrete design and construction
in Concrete International, vol 17, No. 9, dated September.
American Society for Testing and Materials, 2004, Standard specification for water vapor
retarders used in contact with soil or granular fill under concrete slabs.
, 1998, Standard practice for installation of water vapor retarder used in contact with
earth or granular fill under concrete slabs. Designation: E 1643-98 (Re-approved
2005).
, 1997, Standard specification for plastic water vapor retarders used in contact with
soil or granular fill under concrete slabs. Designation: E 1745-97 (Re-approved
2004).
Blake, Thomas F., 2000a, EQFAULT, A computer program for the estimation of peak
horizontal acceleration from 3-D fault sources; Windows 95/98 version.
, 2000b, EQSEARCH, A computer program for the estimation of peak horizontal
acceleration from California historical earthquake catalogs; Updated to July 2013,
Windows 95/98 version.
Bureau Veritas, undated. Grading plans: El Camino Real widening, Tamarack Avenue to
Chestnut Avenue, Sheet 22 of 77, 20-scale, City of Carisbad Project No.: 3957,
Drawing No.: 460-6.
GeoSoils, Inc.
California Building Standards Commission, 2013, California Building Code, California Code
of Regulations, Title 24, Part 2, Volume 2 of 2, Based on the 2012 International
Building Code, 2013 California Historical Building Code, Title 24, Part 8; 2013
California Existing Building Code, Title 24, Part 10.
California Department of Transportation, 2010, Caltrans, Standard specifications. May
printing.
Cao, T., Bryant, W.A., Rowshandel, B., Branum, D., and willis, C.J., 2003, The revised 2002
California probalistic seismic hazard maps, dated June,
http://vvww.conversation.ca.gov/cgs/rghm/psha/fault_parameters/pdf/documents
/2002_ca_hazardmaps.pdf
City of Cartsbad, 2004, Engineering standards, general design standards, vol. 1.
County of San Diego, Department of Planning and Land Use, 2007, Low impact
development (LID) handbook, stormwater management strategies,
dated December 31.
David Evans and Associates, Inc. and Leighton and Associates, Inc., 1992, City of
Carisbad geotechnical hazards analysis and mapping study, dated November.
GeoSoils, Inc., 1989, Preliminary geotechnical study. El Camino Real near Chestnut,
Cartsbad, California, W.O. 1050-SD, dated September 12.
Gregory, G.H., 2003, GSTABL7 with STEDwin, slope stability analysis system; Version
2.004.
International Conference of Building Officials, 1998, Maps of known active fault near-source
zones in California and adjacent portions of Nevada.
Kanare, H., 2005, Concrete floors and moisture, Portland Cement Association, Skokie,
Illinois.
Ninyo and Moore, 2009, Geotechnical evaluation. El Camino Real widening, Sprague
property, Carlsbad, California, Project No.: 106641002, dated December 31.
Seed, 2005, Evaluation and mitigation of soil liquefaction hazard "evaluation of field data
and procedures for evaluating the risk of triggering (or inception) of liquefaction",
in Geotechnical earthquake engineering; short course, San Diego, California,
April 8-9.
State of California, 2014, Civil Code, Title 7, Division 2, Section 895, et seq.
The Kevane Company, Inc. ^ Appendix A
File:e:\wp12\6600\6635a.ruge GcoSoilS, InC. Page 2
State of California, Department of Transportation, 2012, Highway design manual of
instructions, dated May 7.
Tan, S.S., and Giffen, D.G., 1995, Landslide hazards in the northern part ofthe San Diego
Metropolitan area, San Diego County, California, Landslide hazard identification
map no. 35, Plate 35A, Departmentof Conservation, Division of Mines and Geology,
DMG Open File Report 95-04.
United States Geological Survey, 2013, U.S. Seismic design maps, earthquake hazards
program, http://geohazards.usgs.gov/designmaps/us/application.php. Version
3.1.0, dated July.
Walsh Engineering and Land Surveying, Inc., 2013, Conceptual lot split design, APN 167-
230-24 & -25,1 sheet, 30-scale, dated December 20.
The Kevane Company, Inc. , Appendix A
File:e:\wp12\6600\6635a.ruge GcoSoilS, InC. Page 3
APPENDIX B
TEST PIT LOGS
GeoSoils, Inc.
UNIFIED SOIL CLASSIFICATION SYSTEM CONSISTENCY OR RELATIVE DENSITY
Major Divisions Group
Symbols Typical Names CRITERIA
o o
CM o' 2 c o
TJ (U c
o w
•a
(U
c 2
o
in c
10
x:
o
o ^ o
ID
o ii 2
o 10
S
0)
(D
g.° •«
i 5 (D z
CO ±= J2 10 £ g S
§ 8 !§
'= a.
GW Well-graded gravels and gravel-
sand mixtures, little or no fines Standard Penetration Test
ID
(3 GP
Poorly graded gravels and
gravel-sand mixtures, little or no
fines
GM Silty gravels gravel-sand-siit
mixtures
GC Clayey gravels, gravel-sand-clay
mixtures
a -a
O CO
SW Well-graded sands and gravelly
sands, little or no fines
Penetration
Resistance N
(blows/ft)
Relative
Density
0-4 Very loose
4-10 Loose
10-30 Medium
30-50 Dense
> 50 Very dense
SP Poorly graded sands and
gravelly sands, little or no fines
SM Silty sands, sand-silt mixtures
IP
> IT-CO U-
SC Clayey sands, sand-clay
mixtures
s
o o
10 CM
CO ^
Vs «
.£ 10
.£ o E
o
in
ML
tn
O J ®
•= -* m
CO
Inorganic silts, very fine sands,
rock flour, silty or clayey fine
sands
standard Penetration Test
GL
Inorganic clays of low to
medium plasticity, gravelly clays,
sandy clays, silty clays, lean
clays
OL Organic silts and organic silty
clays of low plasticity
^ -c £
III
MH
Inorganic silts, micaceous or
diatomaceous fine sands or silts,
elastic silts
CH Inorganic clays of high plasticity,
fat clays
OH Organic clays of medium to high
plasticity
Penetration
Resistance N
(blows/ft) Consistency
Unconfined
Compressive
Strength
(tons/ft')
<2 Very Soft <0.25
2-4 Soft 0.25 - .050
4-8 Medium 0.50 -1.00
8-15 Stiff 1.00 - 2.00
15-30 Very Stiff 2.00 - 4.00
>30 Hard >4.00
Highly Organic Soils PT Peat, mucic, and other highly
organic soils
3" 3/4" #4 #10 #40 #200 U.S. Standard Sieve
Unified Soil Cobbles
Gravel Sand Silt or Clay
Classification Cobbles
coarse fine coarse medium fine
Silt or Clay
MOISTURE CONDITIONS
Dry Absence of moisture: dusty, dry to the touch
Slightly Moist Below optimum moisture content for compaction
Moist Near optimum moisture content
Very Moist Above optimum moisture content
Wet Visible free water; below water table
MATERIAL QUANTITY
trace
few
little
some
0 - 5 %
5-10%
10-25%
25 - 45 %
OTHER SYMBOLS
C Core Sample
S SPT Sample
B Bulk Sample
^* Groundwater
Qp Pocket Penetrometer
BASIC LOG FORMAT:
Group name, Group symbol, (grain size), color, moisture, consistency or relative density. Additional comments: odor, presence of roots, mica, gypsum,
coarse grained particles, etc.
EXAMPLE:
Sand (SP), fine to medium grained, brown, moist, loose, trace silt, little fine gravel, few cobbles up to 4" in size, some hair roots and rootlets.
File: Mgr: c;\SoilClassif.wpd PLATE B-1
w.o. 6653-A-SC
Kevane Co.
APNs 167-230-24 and -25, Carlsbad
Logged By: RB
January 15, 2014
LOG OF EXPLORATORY TEST PITS
TEST ?
PIT NO.^
ELEV.
-m-
IDEPTH
-m
GROUP
SYMBOL'
SAMPLE
DEPTH
(ft.)
MOISTURE
(%)
FIELD DRY
DENSITY
(pcf)
DESCRIPTION
TP-101 264± 0 - 2V2 SC Bulk @
0 - 1
ARTIFICIAL FILL (UNDOCUMENTED)/QUATERNARY TALUS -TP-101 264± 0 - 2V2 SC Bulk @
0 - 1 UNDIFFERENTIATED: CLAYEY SAND, brown, liqht qrav, and reddish
yellow, damp, loose; abundant sub-rounded and rounded pebble-to
cobble-sized clasts, abundant angular fragments of parent material.
TP-101 264±
2V2 - 4Vz SC WEATHERED SANTIAGO FORMATION: CLAYEY SAND, brownish
gray and light gray, moist, loose becoming dense at 3V2'; fine to
coarse grained.
TP-101 264±
SM TERTIARY SANTIAGO FORMATION: SILTY SANDSTONE w/ trace
clay, yellowish gray, moist, dense; fine to coarse grained.
TP-101
Total Depth = 4V2'
No Groundwater/Caving encountered
Backfilled 1-15-2014
TP-102 267 ± SM WEATHERED SANTIAGO FORMATION: SILTY SAND, liqht brownish
gray, damp, loose; trace organics.
TP-102 267 ±
% - 2 SM Und. @ I'A 8.7 122.3 TERTIARY SANTIAGO FORMATION: SILTY SANDSTONE w/trace
clay, light yellowish gray, moist, dense becoming very dense at IVa'.
TP-102
Total Depth = 2'
No Groundwater/Caving encountered
Backfilled 1-15-2014
PLATE B-2
w.o. 6653-A-SC
Kevane Co.
APNs 167-230-24 and -25, Carlsbad
Logged By: RB
January 15, 2014
LOG OF EXPLORATORY TEST PITS
TEST
PIT NO.
ELEV.
(ft.)
DEPTH
(ft.)
GROUP
SYMBOL
SAMPLE
DEPTH
(ft.)
MOISTURE
(%) .
FIELD DRY
DENSITY
(pcf)
DESCRIPTION
TP-103 264 ± 0 - 'A SM WEATHERED SANTIAGO FORMATION: SILTY SAND w/ trace clay,
light yellowish gray, dry, medium dense; fine to coarse grained.
Joint: N8°W/89°8W.
'74 - 1 '74 SC TERTIARY SANTIAGO FORMATION: CLAYEY SANDSTONE, light
yellowish gray, damp, dense; fine to coarse grained, trace angular
pebble-sized clasts. Contact at rA': N68°W/50°SW (Erosional).
11/4 - 2y4 CL Und. @ iy4
Sm. Bag @
1 y4 -1 Vz
16.2 107.2 MUDSTONE, greenish gray and reddish yellow, wet, very stiff; highly
fractured without discernable orientation. Weak Bedding:
N33°E/15°NW.
Total Depth = 2y4'
No Groundwater/Caving Encountered
Backfilled 1-15-2014
TP-104 254: 0-3
3 - 3y4
3y4 - 4
SM
CL
SC
Und. @ 2
Bulk @ 1
5.1 104.9 ARTIFICIAL FILL - UNDOCUMENTED: SILTY SAND w/ trace clay,
brown and dark gray, dry, loose; abundant asphaltic concrete
fragments, concrete fragments, and miscellaneous trash.
QUATERNARY COLLUVIUM: SANDY CLAY, dark brown, moist, stiff.
WEATHERED SANTIAGO FORMATION: CLAYEY SAND, brownish
gray, damp, medium dense; fine to coarse grained.
Practical refusal due to obstruction at 4'
No Groundwater encountered
Sloughing encountered at 0 - 3'
Backfilled 1-15-2014
PLATE B-3
W.O. 6653-A-SC
Kevane Co.
APNs 167-230-24 and -25, Carlsbad
Logged By: RB
January 15, 2014
LOG OF EXPLORATORY TEST PITS
TEST
PIT NO.
^EtEV."
(ft.)
DEPTH
(ft.)
GROUP
SYMBOL 1 i^DfiWH,
(ft.)
MOISTURE '
(%)
FIELD DRY
DENSITY "
(pcf)
DESCRIPTION " ' ^
TP-105 289± o-y4 SM ARTIFICIAL FILL (UNDOCUMENTED): SILTY SAND, brownish qrav.
gray, and reddish yellow, dry, loose; abundant rounded pebbles and
cobbles, angular fragments of parent material.
TP-105 289±
y4 - Vs SP QUATERNARY VERY OLD PARALIC DEPOSITS: SANDSTONE,
reddish yellow and gray, dry, very dense; fine to medium grained.
TP-105
Practical refusal at Va'
No Groundwater/Caving encountered
Backfilled on 1-15-2014
PLATE B-4
APPENDIX C
SEISMICITY DATA
_ GeoSoils, Inc.
I
***********************
* *
* EQFAULT *
* *
* Version 3.00 *
* *
***********************
DETERMINISTIC ESTIMATION OF
PEAK ACCELERATION FROM DIGITIZED FAULTS
JOB NUMBER: 6653-A-SC
DATE: 03-19-2014
JOB NAME: THE KEVANE COMPANY, INC.
CALCULATION NAME: 6653
FAULT-DATA-FILE NAME: C:\Program Files\EQFAULTl\CGSFLTE.DAT
SITE COORDINATES:
SITE LATITUDE: 33.1622
SITE LONGITUDE: 117.3187
SEARCH RADIUS: 64.2 mi
ATTENUATION RELATION: 12) Bozorgnia Campbell Niazi (1999) Hor.-Soft Rock-Cor.
UNCERTAINTY (M=Median, S=Sigma): S Number of Sigmas: 1.0
DISTANCE MEASURE: cdiSt
SCOND: 1
Basement Depth: .00 km Campbell SSR: 1 Campbell SHR: 0
COMPUTE PEAK HORIZONTAL ACCELERATION
FAULT-DATA FILE USED: C:\Program Files\EQFAULTl\CGSFLTE.DAT
MINIMUM DEPTH VALUE (km): 3.0
Page 1
W.O. 6653-A-SC
PLATE C-1
EQFAULT SUMMARY
DETERMINISTIC SITE PARAMETERS
Page 1
ESTIMATED MAX. EARTHQUAKE EVENT
APPROXIMATE
ABBREVIATED DISTANCE MAXIMUM PEAK EST. SITE
FAULT NAME mi (km) EARTHQUAKE SITE INTENSITY
MAG (Mw) ACCEL, g MOD.MERC.
ROSE CANYON 6. 5( 10. 5) 7 2 0 544 X
NEWPORT-INGLEWOOD (Offshore) 6. 6( 10. 7) 7 1 0 516 X
CORONADO BANK 22. 3( 35. 9) 7 6 0 255 IX
ELSINORE (TEMECULA) 23. 0( 37. 0) 6 8 0 145 VIII
ELSINORE (JULIAN) 23. 2( 37. 3) 7 1 0 176 VIII
ELSINORE (GLEN IVY) 33. 3( 53. 6) 6 8 0 099 VII
SAN JOAQUIN HILLS 35. 9( 57. 7) 6 6 0 114 VII
PALOS VERDES 36. 9( 59. 4) 7 3 0 126 VIII
EARTHQUAKE VALLEY 42. 7( 68. 7) 6 5 0 062 VI
SAN JACINTO-ANZA 45. 6( 73. 4) 7 2 0 094 VII
SAN JACINTO-SAN JACINTO VALLEY 46. 2( 74. 4) 6 9 0 075 VII
NEWPORT-INGLEWOOD (L.A.Basin) 46. 6( 75. 0) 7 1 0 086 VII
CHINO-CENTRAL AVE. (Elsinore) 47. 7( 76. 8) 6 7 0 089 VII
SAN JACINTO-COYOTE CREEK 51. K 82. 3) 6 6 0 055 VI
WHITTIER 51. 6( 83. 1) 6 8 0 062 VI
ELSINORE (COYOTE MOUNTAIN) 57. 0( 91. 8) 6 8 0 056 VI
SAN JACINTO-SAN BERNARDINO 59. 3( 95. 4) 6 7 0 050 VI
PUENTE HILLS BLIND THRUST 61. 7( 99. 3) 7 1 0 091 VII
*******************************************************************************
-END OF SEARCH-
THE ROSE CANYON
18 FAULTS FOUND WITHIN THE SPECIFIED SEARCH RADIUS.
FAULT IS CLOSEST TO THE SITE.
IT IS ABOUT 6.5 MILES (10.5 km) AWAY.
LARGEST MAXIMUM-EARTHQUAKE SITE ACCELERATION: 0.5436 g
Page 2
W.O. 6653-A-SC
PLATE C-2
1100
1000 —
300 —
CALIFORNIA FAULT MAP
THE KEVANE COMPANY, INC.
llllllllllllll
-400 -300 -200 -100 0 100 200 300 400 500 600
W.O. 6653-A-SC
PLATE C-3
MAXIMUM EARTHQUAKES
THE KEVANE COIVIPANY, INC.
3 c o
*3 (0 i_
0)
"o o o
<
.01
.001
•
•
•
w ff
1
.1 10
Distance (mi)
100
W.o. 6653-A-SC
PLATE C-4
I
I
I
*************************
* *
* EQSEARCH *
* *
* Version 3.00 *
* *
*************************
ESTIMATION OF
PEAK ACCELERATION FROM
CALIFORNIA EARTHQUAKE CATALOGS
JOB NUMBER: 6653-A-SC
DATE: 03-19-2014
JOB NAME: THE KEVANE COMPANY, INC.
EARTHQUAKE-CATALOG-FILE NAME: ALLQUAKE.DAT
SITE COORDINATES:
SITE LATITUDE: 33.1622
SITE LONGITUDE: 117.3187
SEARCH DATES:
START DATE: 1800
END DATE: 2013
SEARCH RADIUS:
62.2 mi
100.1 km
ATTENUATION RELATION: 12) Bozorgnia Campbell Niazi (1999) Hor.-Soft Rock-Cor.
UNCERTAINTY (M=Median, S=Sigma): S Number of Sigmas: 1.0
ASSUMED SOURCE TYPE: SS [SS=Strike-slip, DS=Reverse-slip, BT=Blind-thrust]
SCOND: 1 Depth Source: A
Basement Depth: .00 km Campbell SSR: 1 Campbell SHR: 0
COMPUTE PEAK HORIZONTAL ACCELERATION
MINIMUM DEPTH VALUE (km): 3.0
Page 1
W.O. 6653-A-SC
PLATE C-5
EARTHQUAKE SEARCH RESULTS
Page 1
FILE
CODE
LAT.
NORTH
LONG.
WEST
DATE
TIME
(UTC)
H M Sec
DEPTH
(km)
QUAKE
MAG.
SITE
ACC.
g
SITE! APPROX.
MM 1 DISTANCE
INT. 1 mi [km]
DMG 33 OOOO 117 3000 11/22/1800 2130 0. 0 0 0 6 50 0 241 IX 11 2( 18 1
MGI 33 OOOO 117 OOOO 09/21/1856 730 0. 0 0 0 5 00 0 050 VI 21 6( 34 7
MGI 32 8000 117 1000 05/25/1803 0 0 0. 0 0 0 5 00 0 038 V 28 0( 45. 1
DMG 32 7000 117 2000 05/27/1862 20 0 0. 0 0 0 5 90 0 056 VI 32 6( 52 5
PAS 32 9710 117 8700 07/13/1986 1347 8. 2 6 0 5 30 0 037 V 34 5( 55 5
T-A 32 6700 117 1700 12/00/1856 0 0 0. 0 0 0 5 00 0 030 V 35 1( 56 4
T-A 32 6700 117 1700 10/21/1862 0 0 0 0 0 0 5 00 0 030 V 35 1( 56 4
T-A 32 6700 117 1700 05/24/1865 0 0 0 0 0 0 5 00 0 030 V 35 1( 56 4
DMG 33 2000 116 7000 01/01/1920 235 0 0 0 0 5 00 0 030 V 35 8( 57 7
DMG 33 7000 117 4000 05/13/1910 620 0 0 0 0 5 00 0 028 V 37 4( 60 2
DMG 33 7000 117 4000 05/15/1910 1547 0 0 0 0 6 00 0 052 VI 37 4( 60 2
DMG 33 7000 117 4000 04/11/1910 757 0 0 0 0 5 00 0 028 V 37 4( 60 2
DMG 33 6990 117 5110 05/31/1938 83455 4 10 0 5 50 0 037 V 38 7( 62 2
DMG 32 8000 116 8000 10/23/1894 23 3 0 0 0 0 5 70 0 041 V 39 1( 62 9
MGI 33 2000 116 6000 10/12/1920 1748 0 0 0 0 5 30 0 030 V 41 6( 67 0 DMG 33 7100 116 9250 09/23/1963 144152 6 16 5 5 00 0 024 V 44 1( 71 0
DMG 33 7500 117 OOOO 04/21/1918 223225 0 0 0 6 80 0 073 VII 44 5( 71 7
DMG 33 7500 117 OOOO 06/06/1918 2232 0 0 0 0 5 00 0 024 IV 44 5( 71.7
MGI 33 8000 117 6000 04/22/1918 2115 0 0 0 0 5 00 0 022 IV 46 9( 75 5
DMG 33 8000 117 OOOO 12/25/1899 1225 0 0 0 0 6 40 0 052 VI 47 7( 76 8
DMG 33 5750 117 9830 03/11/1933 518 4 0 0 0 5 20 0 025 V 47 7( 76. 8
DMG 33 6170 117 9670 03/11/1933 154 7 8 0 0 6 30 0 047 VI 48 8( 78. 5
GSP 33 5290 116 5720 06/12/2005 154146 5 14 0 5 20 0 024 IV 50 0( 80. 4
DMG 33 6170 118 0170 03/14/1933 19 150 0 0 0 5 10 0 022 IV 51 1( 82. 2
GSG 33 4200 116 4890 07/07/2010 235333 5 14 0 5 50 0 027 V 51.1( 82. 2
DMG 33 9000 117 2000 12/19/1880 0 0 0 0 0 0 6 00 0 037 V 51 4( 82. 7
PAS 33 5010 116 5130 02/25/1980 104738 5 13 6 5 50 0 027 V 52 0( 83. 7
GSP 33 5080 116 5140 10/31/2001 075616 6 15 0 5 10 0 021 IV 52 2( 84. 0
DMG 33 OOOO 116 4330 06/04/1940 1035 8 3 0 0 5 10 0 021 IV 52 4( 84. 4
DMG 33 5000 116 5000 09/30/1916 211 0 0 0 0 5 00 0 020 IV 52 7( 84. 8
DMG 33 6830 118 0500 03/11/1933 658 3 0 0 0 5 50 0 025 V 55 4( 89. 1
DMG 33 7000 118 0670 03/11/1933 51022 0 0 0 5 10 0 019 IV 56 9( 91.6
DMG 33 7000 118 0670 03/11/1933 85457 0 0 0 5 10 0 019 IV 56 9( 91. 6
DMG 33 3430 116 3460 04/28/1969 232042 9 20 0 5 80 0 029 V 57 5( 92. 6
DMG 34 OOOO 117 2500 07/23/1923 73026 0 0 0 6 25 0 038 V 58 0( 93. 3
MGI 34 OOOO 117 5000 12/16/1858 10 0 0 0 0 0 7 00 0 062 VI 58 8( 94. 6
DMG 33 7500 118 0830 03/11/1933 230 0 0 0 0 5 10 0 018 IV 59 9( 96. 4
DMG 33 7500 118 0830 03/11/1933 323 0 0 0 0 5 00 0 017 IV 59 9( 96. 4
DMG 33 7500 118 0830 03/11/1933 910 0 0 0 0 5 10 0 018 IV 59 9( 96. 4
DMG 33 7500 118 0830 03/13/1933 131828 0 0 0 5 30 0 021 IV 59 9( 96. 4
DMG 33 7500 118 0830 03/11/1933 2 9 0 0 0 0 5 00 0 017 IV 59 9( 96. 4
GSG 33 9530 117 7610 07/29/2008 184215 7 14 0 5 30 0 020 IV 60 2( 96. 9
DMG 33 9500 116 8500 09/28/1946 719 9 0 0 0 5 00 0 017 IV 60 7( 97. 7
DMG 33 4000 116 3000 02/09/1890 12 6 0 0 0 0 6 30 0 037 V 61 0( 98. 2
*******************************************************************************
I
I
Page 2
W.O. 6653-A-SC
PLATE C-6
-END OF SEARCH- 44 EARTHQUAKES FOUND WITHIN THE SPECIFIED SEARCH AREA.
TIME PERIOD OF SEARCH: 1800 TO 2013
LENGTH OF SEARCH TIME: 214 years
THE EARTHQUAKE CLOSEST TO THE SITE IS ABOUT 11.2 MILES (18.1 km) AWAY.
LARGEST EARTHQUAKE MAGNITUDE FOUND IN THE SEARCH RADIUS: 7.0
LARGEST EARTHQUAKE SITE ACCELERATION FROM THIS SEARCH: 0.241 g
COEFFICIENTS FOR GUTENBERG & RICHTER RECURRENCE RELATION:
a-value= 0.905
b-value= 0.364
beta-value= 0.837
TABLE OF MAGNITUDES AND EXCEEDANCES:
Earthquake 1 Number of Times
Magnitude | Exceeded
Cumulative
NO. / Year
4.0
4.5
5.0
5.5
6.0
6.5
7.0
44
44
44
16
9
3
1
0.20657
0.20657
0.20657
0.07512
0.04225
0.01408
0.00469
Page 3
W.O. 6653-A-SC
PLATE C-7
EARTHQUAKE EPICENTER MAP
THE KEVANE COMPANY, INC.
1100
1000 --
900
800
700
600
500 ~
400 —
300
200
100 —
0 —
-100 -n
-400 -300 -200 -100 0 100 200 300 400 500 600
W.O. 6653-A-SC
PLATE C-8
(0 0)
>-
z
(0
c
>
UJ
0)
E
3
z
0)
>
«
3 E E
3
o
100
10
.1
.01
.001
EARTHQUAKE RECURRENCE CURVE
THE KEVANE COMPANY, INC.
< f ^""^
<
llll llll llll llll llll llll llll llll llll IIII
1
3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0
Magnitude (M)
w.o. 6653-A-SC
PLATE C-9
APPENDIX D
LABORATORY TEST RESULTS
GeoSoils, Inc.
^Cal Lanci Engineering, Inc.
dba Quartecli Consultant
Geotechnical, Environmental, and Civil Engineering
SUMMARY OF LABORATORY TEST DATA
GeoSoils, Inc.
5741 Palmer Way, Suite D
Carlsbad, CA 92010
Client: Kevane
W.O. 6653-A-SC
QCI Project No.: 14-029-01h
Date: January 31, 2014
Summarized by: KA
Corrosivity Test Results
Sample ID Sample
Depth
pH
CT-532
(643)
Chloride
CT-422
(ppm)
Sulfate
CT-417
%By
Weight
Resistivity
CT-532 (643)
(ohm-cm)
TP-101, (g 0-1'
TP-104(g1.5'-2'
Mix
0-1'
&1.5'-2' 6.61 87 0.0015 2,250
I
I
w.o. 6653-A-SC
PLATE D-1
576 East Lambert Road, Brea, Catifornia 92821; Tel: 714-671-1050; Fax: 714-671-1090
APPENDIX E
SLOPE STABILITY
I
GeoSoils, Inc.
I
SLOPE STABILITY ANALYSIS
INTRODUCTION OF GSTABL7 v.2 COMPUTER PROGRAM
Introduction
GSTABL7 v.2 Is a fully Integrated slope stability analysis program. It pernnlts the engineer
to develop the slope geonnetry interactively and perfornn slope analysis from within a single
program. The slope analysis portion of GSTABL7 v.2 uses a modified version of the
popular STABL program, originally developed at Purdue University.
GSTABL7 v.2 performs a two dimensional limit equilibrium analysis to compute the factor
of safety (FOS) for a layered slope using the simplified Bishop or Janbu methods. This
program can be used to search forthe most critical surface orthe FOS may be determined
for specific surfaces. GSTABL7, Version 2, is programmed to handle:
1. Heterogenous soil systems
2. Anisotropic soil strength properties
3. Reinforced slopes
4. Nonlinear Mohr-Coulomb strength envelope
5. Pore water pressures for effective stress analysis using:
a. Phreatic and piezometric surfaces
b. Pore pressure grid
c. R factor
d. Constant pore water pressure
6. Pseudo-static earthquake loading
7. Surcharge boundary loads
8. Automatic generation and analysis of an unlimited number of circular, noncircular
and block-shaped failure surfaces
9. Analysis of right-facing slopes
10. Both SI and Imperial units
General Information
If the reviewer wishes to obtain more information concerning slope stability analysis, the
following publications may be consulted initially:
1. The Stabilitv of Slopes, by E.N. Bromhead, Surrey University Press, Chapman and
Hall, N.Y., 411 pages, ISBN 412 01061 5, 1992.
2. Rock Slope Enqineerinq. by E. Hoek and J.W. Bray, Inst. of Mining and Metallurgy,
London, England, Third Edition, 358 pages, ISNB 0 900488 573, 1981.
3. Landslides: Analvsis and Control, by R.L. Schuster and R.J. Krizek (editors). Special
Report 176, Transportation Research Board, National Academy of Sciences,
234 pages, ISBN 0 309 02804 3, 1978.
GeoSoils, Inc.
GSTABL7 v.2 Features
The present version of GSTABL7 v.2 contains the following features:
1. Allows user to calculate FOS for static stability and seismic stability evaluations.
2. Allows user to analyze stability situations with different failure modes.
3. Allows user to edit Input for slope geometry and calculate corresponding FOS.
4. Allows user to readily review on-screen the input slope geometry.
5. Allows userto automatically generate and analyze defined numbers of circular, non-
circular and block-shaped failure surfaces (i.e., bedding plane, slide plane, etc.).
Input Data
Input data Includes the following Items:
1. Unit weight, residual cohesion, residual friction angle, peak cohesion, and peak
friction angle of earth materials and bedding planes. Residual cohesion and friction
angle Is used for static stability analysis. Where as, peak cohesion and friction
angle is for dynamic stability analysis.
2. Slope geometry and surcharge boundary loads.
3. Apparent dip of bedding plane can be modeled In an anisotropic angular range (i.e.,
from 0 to 90 degrees. With the exception of the Tertiary Santiago Formation,
isotropic values were used for all earth materials. For the Tertiary Santiago
Formation, GSI used an anisotropic angular range of 3 degrees in Into- and out-of-
slope directions. GSI also incorporated cross- bed and parallel bed strengths for
the Santiago Formation.
4. Pseudo-static earthquake loading. A seismic coefficient of 0.15/ and a peak
horizontal ground acceleration of 0.43 g were used in the analyses.
5. A 20 percent (20%) increase In soil strengths to model transient seismic loading of
the slope, as is customary in geotechnical practice was used in these analyses.
6. Soil parameters used in the slope stability analyses are provided in the following
table:
The Kevane Company, Inc. Appendix E
File:wp12\6600\6653a.rgua GCOSollS, InC. Page 2
TABLE E-1 - SOIL STRENGTH PARAMETERS
• nil'ir'i
SOIL MATERIALS
SOIL UNIT
WEIGHT (pcf)
STATIC SHEAR
STRENGTH PARAMETERS
SEISMIC SHEAR
i STRENGTH PARAMETERS
• nil'ir'i
SOIL MATERIALS
Moist Saturated
(l> (degrees) (p (degrees) • nil'ir'i
SOIL MATERIALS
Moist Saturated '•si Pecjdlng
• nil'ir'i
SOIL MATERIALS
Moist Saturated
Cross Parallel Cross Parallel Cross Parallel Cross Parallel
Tertiary Santiago
Formation
(Tsa)
115 125 300 240 35 29 360 288 40 33.6
Quaternary Very Old
Paralic Deposits
(Qvop)
124 135 150 29 180 33.6
Artificial Fill - Engineered
(Afe) 117 130 176 32 180 36.8
Artificial Fill-
Undocumented
(Afu)
104 120 176 30 Not Used Not Used
Seismic Discussion
Seismic stability analyses were approximated using a pseudo-static approach. The major
difficulty in the pseudo-static approach arises from the appropriate selection ofthe seismic
coefficient used in the analysis. The use of a static Inertia force equal to this acceleration
during an earthquake (rigid-body response) would be extremely conservative for several
reasons including: (1) only low height, stiff/dense embankments or embankments In
confined areas may respond essentially as rigid structures; (2) an earthquake's inertia force
is enacted on a mass for a short time period. Therefore, replacing a transient force by a
pseudo-static force representing the maximum acceleration may be considered overly
conservative; (3) assuming that total pseudo-static loading is applied evenly throughout
the embankment for an extended period of time is an incorrect assumption, as the length
of the failure surface analyzed is usually much greater than the wave length of seismic
waves generated by earthquakes; and (4) the seismic waves would place portions ofthe
mass in compression and some in tension, resulting in only a limited portion ofthe failure
surface analyzed moving in a downslope direction, at any one instant of earthquake
loading.
The coefficients usually suggested by regulating agencies, counties and municipalities are
in the range of O.OSg to 0.25g. For example, past regulatory guidelines within the city and
county of Los Angeles Indicated that the slope stability pseudostatic coefficient = 0.1 to
0.15/.
The method developed by Krinitzsky, Gould, and Edinger (1993) which was in turn based
on Taniguchi and Sasaki (1986), was referenced. This method Is based on empirical data
and the performance of existing earth embankments during seismic loading. Our review
of "Guidelines for Evaluating and Mitigating Seismic Hazards in California" (Davis, 1997)
The Kevane Company, Inc.
File:wp12\6600\6653a.rgua GeoSoils, Inc. Appendix E
Page 3
indicates the State of California recommends using pseudo-static coefficient of 0.15/ for
design earthquakes of M 8.25 or greater and using 0.1 for earthquake parameter M 6.5.
Therefore, for reasonable conservatism, a seismic coefficient of 0.15/ was used in our
analysis for a M7.2 event on the Rose Canyon fault. GSI also incorporated a peak
horizontal ground acceleration (PGAJ of 0.43 g into the seismic analysis.
Output Information
Output information includes:
1. All input data.
2. FOS for the 10 most critical surfaces for static and pseudo-static stability situation.
3. High quality plots can be generated. The plots include the slope geometry, the
critical surfaces and the FOS.
4. Note, that in the analysis, 100 to 1,000 trial surfaces were analyzed for each section
for either static or pseudo-static analyses.
Results of Slope Stabilitv Calculations
The following table provides a summary of the results of our stability analyses for the
graded and temporary backcut configurations shown on Geologic Cross Sections A-A'
and B-B'(see Plate 2). Computer printouts from the GSTABL7 program are also Included
herein.
TABLE E-2 - SUMMARY OF SLOPE STABILITY ANALYSES
LOCATION
FACTOR OF SAFETY (FOS) '
EkiSTING SLOPE CONDITION iiiiiipM
METHOD ; COMMENTS LOCATION
STATIC SEISMIC
iiiiiipM
METHOD ; COMMENTS
Section A-A'
Global
1.54
(See Plate E-1)
1.42
(See Plate E-2) Janbu Adequate
Factors-of-Safety
Section A-A'
Reinforced Fill
1.34
(See Plate E-3)
1.18
(See Plate E-4) Janbu Inadequate Static
Factor-of-Safety
Section A-A'
Mid-Reinforced Fill
1.48
(See Plate E-5)
1.34
(See Plate E-6) Janbu Inadequate to Marginal
Static Factor-of-Safety
Section A-A'
Backcut
1.29
(See Plate E-7) Not Analyzed Janbu Adequate Temporary
Factor-of-Safety
Section B-B'
Upper Slope- Global
1.58
(See Plate E-8)
1.38
(See Plate E-9) Janbu Adequate
Factors-of Safety
Section B-B'
Backcut
1.59
(See Plate E-10) Not Analyzed Janbu Adequate Temporary
Factor-of-Safety
The Kevane Company, Inc.
File: wpl 2\6600\6653a.rgua GeoSoils, Inc. Appendix E
Page 4
6653-A-SC The Kevane Co. Section A-A' Janbu Global Static
z:\shared\word perfect data\carlsbad\6600\6653 kevane company\slope stabilityVin-progress filesVfinal plots and outputVoutput files\6653-a-sc kevane a-a' janbu static global.pl2 Run By: Geosoils,Inc 4/21/2014
350
320 -
# FS
a 1.543
b 1.543
c 1.543
d 1.543
e 1.543
f 1.543
g 1.543
h 1.543
i 1.543
i 1.543
290
260
230
200
-n ^
0) CO
r—.- I
<D >
m CO o
=F
Soil
Desc.
Tsa
Afe
Qvop
Soil Total
Type Unit Wt.
No. (pcf)
1 115.0
2 117.0
3 124.0
Saturated Cohesion Friction
Unit Wt. Intercept Angle
(pcf) (psf) (deg)
125.0 Aniso Aniso
130.0 176.0 32.0
135.0 150.0 29.0
I
Pore Pressure Piez.
Pressure Constant Surface
Param. (psf) ' No.
0.00 0.0 ; 0
0.10 0.0 \ 0
0.10 0.0 : 0
Load
Ll
Value
2000 psf
T
30 60 90 120 150 180 210 240
GSTABL7V.2 FSmin=1.543
Safety Factors Are Calculated By The Simplified Janbu Method
6653-A-SC The Kevane Co. Section A-A' Janbu Global Seismic
z:\shared\word perfect data\carlsbad\6600\6653 kevane companyVslope stabilityMn-progress fllesVfinal plots and outputVoutput filesV6653-a-sc kevane a-a' janbu seismic global.pl2 Run By: Geosoils,Inc 4/21/2014
350
320
# FS
a 1.423
b 1.423
0 1.423
d 1.423
e 1.423
f 1.423
g 1.423
h 1.423
i 1.423
i 1.423
290
260
230
200
Q) (j3 .-f. I
(B >
m Oi to o
=F Soil
Desc.
Tsa
Afe
Qvop
Soil Total
Type Unit Wt.
No. (pcf)
1 115.0
2 117.0
3 124.0
Saturated Cohesion Friction
Unit Wt. Intercept Angle
(pcf) (psf) (deg)
125.0 Aniso Aniso
130.0 211.2 36.8
135.0 180.0 33.6
I
Pore Pressure Piez.
Pressure Constant Surface
Param. (psf) ; No.
0.00 0.0 0
0.10 0.0 i 0
0.10 0.0 0
Load Value
LI 2000 psf
Peak(A) 0.430(g)
khCoef. 0.150(g)<
T
30 60 90 120 150 180
GSTABL7V.2 FSmin=1.423
Safety Factors Are Calcuiated By The Simplified Janbu Method
210 240
6653-A-SC The Kevane Co. Section A-A' Fill Stability
z:\shared\word perfect data\carlsbad\6600\6653 kevane company\stope stability\in-progress filesVfinal plots and outputVoutput files\6653-a-sc kevane a-a' static janbu fill stability.pl2 Run By: Geosoils,lnc 4/21/2014
350
320
# FS
a 1.347
b 1.347
c 1.347
d 1.347
e 1.347
f 1.347
g 1.347
h 1.347
i 1.347
J 1.347
290
260
230
200
cn
-n
01 o>
r-.. I
(D >
rn CO
CA3 O
Soil Soil Total Saturated Cohesion Friction
Desc. Type UnitWt. UnitWt. Intercept Angle
No. (pcf) (pcf) (psf) (deg)
Tsa 1 115.0 125.0 Aniso Aniso
Afe 2 105.0 110.0 176.0 32.0
Qvop 3 124.0 135.0 150.0 29.0
Pore Pressure Piez.
Pressure Constant Surface
Param. (psf) No.
0.00 0.0 : 0
0.10 0.0 i 0
0.10 0.0 0
Load Value
Ll 2000 psf
1'1
30 60 90 120 150 180 210 240
GSTABL7V.2 FSmin=1.347
Safety Factors Are Calculated By The Simplified Janbu Method
6653-A-SC The Kevane Co. Section A-A' Seismic Fill Stability
z:\shared\word perfect data\carlsbad\6600\6653 kevane companyVstope stabilityMn-progress files\final ptots and outputVoutput files\6653-a-sc kevane a-a' seismk; janbu fill stability with soil increase.pl2 Run By: Geosoils.Inc 4/21/2014
350
320
290
260
230
b 200
# FS
a 1.183
b 1.183
c 1.183
d 1.183
e 1.183
f 1.183
g 1.183
h 1.183
i 1.183
j 1.183
Ol CO :5;
01 •—•- • (D > rn CO
Soil Soil Total
Desc. Type UnitWt.
No. (pcf)
Tsa 1 115.0
Afe 2 117.0
Qvop 3 124.0
=F Saturated Cohesion Friction Pore Pressure Piez.
Unit Wt. Intercept Angle Pressure Constant Surface
(pcf)
125.0
130.0
135.0
(psf)
Aniso
211.2
180.0
(deg)
Aniso
36.9
33.6
Param.
0.00
0.10
0.10
(psf)
0.0
0.0
0.0
No.
0
0
0
Load Value
L! 2000 psf
Peak(A) 0.430(g)
khCoef. 0.150(g)<
T
i'l
30 60 90 120 150 180 210 240
GSTABL7V.2 FSmin=1.183
Safety Factors Are Calculated By The Simplified Janbu Method
6653-A-SC The Kevane Co. Section A-A' Mid-Fill Stability
2:\shared\word perfect data\carlsbad\6600\6653 kevane company\slope stabilityMn-progress files\flnal plots and outputVoutput files\6653-a-sc kevane a-a' janbu mid fill stability.pl2 Run By: Geosoils.Inc 4/21/2014
350
320
# FS
a 1.484
b 1.484
c 1.484
d 1.484
e 1.484
f 1.484
g 1.484
K 1.484
i 1.484
j 1,484
290
260
230
200
-n cn 2 Ol 0) a>
r-t. I
(D >
rn CO
OI o
I
Soil Soil Total
Desc. Type UnitWt.
No. (pcf)
Tsa 1 115.0
Afe 2 117.0
Qvop 3 124.0
=F
Saturated Cohesion Friction
Unit wt. Intercept Angle
(pcf) (psf) (deg)
125.0 Aniso Aniso
130.0 176.0 32.0
135.0 150.0 29.0
1 —
Pore Pressure Piez.
Pressure Constant Surface
Param. (psf) No.
0.00 0.0 : 0
0.10 0.0 ^ 0
0.10 0.0 ^ 0
Load
Ll
Value
2000 psf
1*1
30 60 90 120 150 180 210 240
GSTABL7V.2 FSmin=1.484
Safety Factors Are Calculated By The Simplified Janbu Method
6653-A-SC The Kevane Co. Section A-A' Mid-Fill Stability Seismic
z:\shared\word perfect data\carlsbad\6600\6653 kevane companyVslope stabilityMn-progress filesVfinal plots and outputVoutput filesV6653-a-sc kevane a-a' seismic janbu mid fill stabillty.pl2 Run By: Geosoils.Inc 4/21/2014
350
320
# FS
a 1.344
b 1.344
c 1.344
d 1.344
e 1.344
f 1.344
g 1.344
h' 1,344
i 1.344
1,344
290
260
230
200
-n cn 2 Ol
f
a> >
rn CO
O) o
I I =T=
Soil Soil Total Saturated Cohesion Friction
Desc. Type UnitWt. UnitV/Vt. Intercept Angle
No. (pcf) (pcf) (psf) (deg)
Tsa 1 115.0 125.0 Aniso Aniso
Afe 2 117.0 130.0 211.2 36.8
Qvop 3 124.0 135.0 180.0 33.6
I
Pore Pressure Piez.
Pressure Constant Surface
Param. (psf) - No.
0.00 0.0 0
0.10 0.0 0
0.10 0.0 0
Load Value
Ll 2000 psf
Peak(A) 0.430(g)
kh Coef. 0.150(g)<
T T
l'l
30 60 90 120 150 180 210 240
GSTABL7V.2 FSmin=1.344
Safety Factors Are Calculated By The Simplified Janbu Method
6653-A-SC Section A-A' Back-cut
z:VsharedVv\/ord perfect data\carlsbadV6600V6653 kevane companyVslope stabilityMn-progress filesVfinal plots and outputVoutput filesV6653-a-sc kevane a-a' back-cuti .pl2 Run By: Geosoils.Inc 4/21/2014 0
^50
320
290
260
230
200
# FS
a 1.293
b 1.293
c 1.293
d 1.293
e 1.293
f 1.293
g 1.293
h 1:293
i 1.293
j 1,293
Soil
Desc.
Tsa
Afu
Qvop
Soil Total
Type Unit Wt.
No. (pcf)
1 115.0
2 104.0
3 124.0
I I
Saturated Cohesion Friction
Unit Wt. Intercept Angle
(pcf) (psf) (deg)
125.0 Aniso Aniso
120.0 176.0 30.0
135.0 150.0 29.0
Pore Pressure Piez.
Pressure Constant Surface
Param.
0.00
0.10
0.10
(psf)
0.0
0.0
0.0
No.
0
0
0
11
CD -n cn 12 01
Q] CO
.—^ I
CD > rnco
O
30 60 90 120 150 180 210 240
GSTABL7V.2 FSmin=1.293
Safety Factors Are Calculated By The Simplified Janbu Method
6653-A-SC Kevane Co. Section B-B' Global
2:VsharedVword perfect dataVcarlsbadV6600V6653 kevane companyVslope stabilityVin-progress filesVfinal plots and outputVoutput filesV6653-a-sc kevane b-b' janbu upper global.pl2 Run By: Geosoils.Inc 4/21/2014
380 . ' ' . . I ' ' 1
350
320 -
290
260
230
-n cn 2 cn 0) CO l—l- I
<D >
00 O
200
FS
1.584
1.584
1.584
1.584
1,584
1.584
1.584
1.584
1.584
1.584
Sdl
Deslc.
Ts^
Afk
Qvop
Soil Total
Type UnitWt.
No. (pcf)
1 115.0
2 117.0
3 124.0
Saturated Cohesion Friction
Unit\/Vft. Intercept Angle
(pcf) (psf) : (deg)
125.0 Aniso : Aniso
130.0 176.0 : 32.0
135.0 150.0 29.0
Pore Pressure Piez.
Pressure: Constant Surface
Param. : (psf) No.
0.00 0.0 0
0.10 0.0 0
0.10 0.0 0
Load
Ll
Value
200 psf
32
30 60 90 120 150 180 210 240 270
GSTABL7V.2 FSmin=1.584
Safety Factors Are Caiculated By The Simplified Janbu Method
6653-A-SC Kevane Co. Section B-B' Seismic Global
z VsharedVword perfect dataVcarlsbadV6600V6653 kevane companyVslope stabilityVin-progress filesVfinal plots and outputVoutput filesV6653-a-sc kevane b-b' seismk; janbu upper global.pl2 Run By: Geosoils.Inc 4/21/2014
380
350
320
290
260
230
-n cn 12 Ol
0) CO
.—^ I
(D >
m CO
<b O
200
# FS
a 1.386
b 1.386
c 1.386
d 1.386
e 1.386
f 1.386
g 1.386
h 1.386
i 1.386
J 1,386
Soil
Desc.
Ts^
Afe
Qvop
I I
Soil Total Saturated Cohesion Friction
Type UnitV/Vt. UnitWt. Intercept Angle
No. (pcf) : (pcf) (psf) (deg)
1 115.0 125.0 Aniso Aniso
2 117.0 130.0 211.2 36.8
3 124.0 135.0 180.0 33.6
Pore Pressure Piez.
Pressure Constant Surface
Param. (psf) No.
0.00 0.0 0
0.10 i 0.0 0
0.10 i 0.0 0
Load Value
Ll 200 psf
Peak(A) 0.430(g)
khCoef. 0.150(g)<
-oSs5
1 " 1
\32
35 3
-o--.o,VJ5
30 60 90 120 150 180 210 240 270
GSTABL7V.2 FSmin=1.386
Safety Factors Are Calculated By The Simplified Janbu Method
6653-A-SC Kevane Section B-B' Back-cut
z:\sharedVword perfect data\carlsbadV6600V6653 kevane companyVslope stabilityMn-progress filesVfinal plots and outputVoutput filesV6653-a-sc kevane b-b' back-cuti .pl2 Run By: Geosoils.Inc 4/21/2014 0
380
350
320
290
260
230
2
Q>
m
cn Ol CO
200
Crt
o
I I
Soil Total Saturated Cohesion Friction
Type Unit \N{. Unit \/V/t. Intercept Angle
No. (pcf) ^ (pcf) (psf) (deg)
1 115.0 125.0 Aniso Aniso
2 104.0 120.0 176.0 30.0
3 124.0 135.0 150.0 29.0
I H
Pore i Pressure Piez.
Pressure Constant Surface
Param. (psf) No.
0.00 \ 0.0 0
0.10 0.0 0
0.10 0.0 0 :
T T
Tr V 1^
30 60 90 120 150 180 210 240 270
GSTABL7V.2 FSmin=1.591
Safety Factors Are Calculated By The Simplified Janbu Method
APPENDIX F
GENERAL EARTHWORK AND GRADING GUIDELINES
GeoSoils, Inc.
GENERAL EARTHWORK AND GRADING GUIDELINES
General
These guidelines present general procedures and requirements for earthwork and grading
as shown on the approved grading plans. Including preparation of areas to be filled,
placement of fill, installation of subdrains, excavations, and appurtenant structures or
flatwork. The recommendations contained in the geotechnical report are part of these
earthwork and grading guidelines and would supercede the provisions contained hereafter
in the case of conflict. Evaluations performed by the consultant during the course of
grading may result In new or revised recommendations which could supercede these
guidelines or the recommendations contained in the geotechnical report. Generalized
details follow this text.
The contractor Is responsible forthe satisfactorv completion of all earthwork In accordance
with provisions ofthe project plans and specifications and latest adopted code. In the case
of conflict, the most onerous provisions shall prevail. The project geotechnical engineer
and engineering geologist (geotechnical consultant), and/ortheir representatives, should
provide observation and testing services, and geotechnical consultation during the
duration of the project.
EARTHWORK OBSERVATIONS AND TESTING
Geotechnical Consultant
Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer
and engineering geologist) should be employed for the purpose of observing earthwork
procedures and testing the fills for general conformance with the recommendations ofthe
geotechnical report(s), the approved grading plans, and applicable grading codes and
ordinances.
The geotechnical consultant should provide testing and observation so that an evaluation
may be made that the work is being accomplished as specified. It Is the responsibility of
the contractor to assist the consultants and keep them apprised of anticipated work
schedules and changes, so that they may schedule their personnel accordingly.
All remedial removals, clean-outs, prepared ground to receive fill, key excavations, and
subdrain installation should be observed and documented bythe geotechnical consultant
prior to placing any fill. It is the contractor's responsibility to notify the geotechnical
consultant when such areas are ready for observation.
GeoSoils, Inc.
Laboratorv and Field Tests
Maximum dry density tests to determine the degree of compaction should be performed
In accordance with American Standard Testing Materials test method ASTM designation
D-1557. Random or representative field compaction tests should be performed in
accordance with test methods ASTM designation D-1556, D-2937 or D-2922, and D-3017,
at intervals of approximately ±2 feet of fill height or approximately every 1,000 cubic yards
placed. These criteria would vary depending on the soil conditions and the size of the
project. The location and frequency of testing would be at the discretion of the
geotechnical consultant.
Contractor's Responsibilitv
All clearing, site preparation, and earthwork performed on the project should be conducted
bythe contractor, with observation by a geotechnical consultant, and staged approval by
the governing agencies, as applicable. It is the contractor's responsibility to prepare the
ground surface to receive the fill, to the satisfaction of the geotechnical consultant, and to
place, spread, moisture condition, mix, and compact the fill in accordance with the
recommendations ofthe geotechnical consultant. The contractor should also remove all
non-earth material considered unsatisfactory by the geotechnical consultant.
Notwithstanding the services provided by the geotechnical consultant, it is the sole
responsibility ofthe contractorto provide adequate equipment and methods to accomplish
the earthwork In strict accordance with applicable grading guidelines, latest adopted codes
or agency ordinances, geotechnical report(s), and approved grading plans. Sufficient
watering apparatus and compaction equipment should be provided bythe contractor with
due consideration for the fill material, rate of placement, and climatic conditions. If, in the
opinion of the geotechnical consultant, unsatisfactory conditions such as questionable
weather, excessive oversized rock or deleterious material, insufficient support equipment,
etc., are resulting in a quality of work that Is not acceptable, the consultant will inform the
contractor, and the contractor is expected to rectify the conditions, and if necessary, stop
work until conditions are satisfactory.
During construction, the contractor shall properly grade all surfaces to maintain good
drainage and prevent ponding of water. The contractor shall take remedial measures to
control surface water and to prevent erosion of graded areas until such time as permanent
drainage and erosion control measures have been installed.
SITE PREPARATION
All major vegetation, including brush, trees, thick grasses, organic debris, and other
deleterious material, should be removed and disposed of off-site. These removals must
be concluded prior to placing fill. In-place existing fill, soil, alluvium, colluvium, or rock
materials, as evaluated by the geotechnical consultant as being unsuitable, should be
The Kevane Company, Inc. , Appendix F
File:e:Vwp12V6600\6635a.ruge GeoSoilS, InC. Page 2
removed prior to any fill placement. Depending upon the soil conditions, these materials
may be reused as compacted fills. Any materials incorporated as part of the compacted
fills should be approved by the geotechnical consultant.
Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic
tanks, wells, pipelines, or other structures not located priorto grading, are to be removed
or treated in a manner recommended bythe geotechnical consultant. Soft, dry, spongy,
highly fractured, or othenwise unsuitable ground, extending to such a depth that surface
processing cannot adequately improve the condition, should be overexcavated down to
firm ground and approved by the geotechnical consultant before compaction and filling
operations continue. Overexcavated and processed soils, which have been properly
mixed and moisture conditioned, should be re-compacted to the minimum relative
compaction as specified in these guidelines.
Existing ground, which Is determined to be satisfactory for support of the fills, should be
scarified (ripped) to a minimum depth of 6 to 8 inches, or as directed by the geotechnical
consultant. After the scarified ground is broughtto optimum moisture content, or greater
and mixed, the materials should be compacted as specified herein. If the scarified zone
is greaterthan 6 to 8 Inches in depth, it may be necessary to remove the excess and place
the material in lifts restricted to about 6 to 8 inches in compacted thickness.
Existing ground which is not satisfactory to support compacted fill should be
overexcavated as required in the geotechnical report, or by the on-site geotechnical
consultant. Scarification, disc harrowing, or other acceptable forms of mixing should
continue until the soils are broken down and free of large lumps or clods, until the working
surface is reasonably uniform and free from ruts, hollows, hummocks, mounds, or other
uneven features, which would Inhibit compaction as described previously.
Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical
[h:v]), the ground should be stepped or benched. The lowest bench, which will act as a
key, should be a minimum of 15 feet wide and should be at least 2 feet deep into firm
material, and approved by the geotechnical consultant. In fill-over-cut slope conditions,
the recommended minimum width ofthe lowest bench or key is also 15 feet, with the key
founded on firm material, as designated bythe geotechnical consultant. As a general rule,
unless specifically recommended othenA/ise by the geotechnical consultant, the minimum
width of fill keys should be equal to Vz the height of the slope.
Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable
material. Benching may be used to remove unsuitable materials, although it is understood
thatthe vertical height ofthe bench may exceed 4 feet. Pre-stripping may be considered
for unsuitable materials in excess of 4 feet in thickness.
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All areas to receive fill. Including processed areas, removal areas, and the toes of fill
benches, should be observed and approved by the geotechnical consultant prior to
placement of fill. Fills may then be properly placed and compacted until design grades
(elevations) are attained.
COMPACTED FILLS
Any earth materials Imported or excavated on the property may be utilized in the fill
provided that each material has been evaluated to be suitable by the geotechnical
consultant. These materials should be free of roots, tree branches, other organic matter,
or other deleterious materials. All unsuitable materials should be removed from the fill as
directed bythe geotechnical consultant. Soils of poor gradation, undesirable expansion
potential, or substandard strength characteristics may be designated bythe consultant as
unsuitable and may require blending with other soils to serve as a satisfactoryfill material.
Fill materials derived from benching operations should be dispersed throughout the fill
area and blended with other approved material. Benching operations should not result in
the benched material being placed only within a single equipment width away from the
fill/bedrock contact.
Oversized materials defined as rock, or other irreducible materials, with a maximum
dimension greater than 12 inches, should not be buried or placed in fills unless the
location of materials and disposal methods are specifically approved bythe geotechnical
consultant. Oversized material should be taken offsite, or placed In accordance with
recommendations ofthe geotechnical consultant in areas designated as suitable for rock
disposal. GSI anticipates that soils to be utilized as fill material for the subject project may
contain some rock. Appropriately, the need for rock disposal may be necessary during
grading operations on the site. From a geotechnical standpoint, the depth of any rocks,
rock fills, or rock blankets, should be a sufficient distance from finish grade. This depth is
generally the same as any overexcavation due to cut-fill transitions in hard rock areas, and
generally facilitates the excavation of structural footings and substructures. Should deeper
excavations be proposed (i.e., deepened footings, utility trenching, swimming pools, spas,
etc.), the developer may consider increasing the hold-down depth of any rocky fills to be
placed, as appropriate. In addition, some agencies/jurisdictions mandate a specific
hold-down depth for oversize materials placed In fills. The hold-down depth, and potential
to encounter oversize rock, both within fills, and occurring in cut or natural areas, would
need to be disclosed to all interested/affected parties. Once approved by the governing
agency, the hold-down depth for oversized rock (i.e., greaterthan 12 inches) in fills on this
project is provided as 10 feet, unless specified differently In the text of this report. The
governing agency may require that these materials need to be deeper, crushed, or
reduced to less than 12 inches in maximum dimension, at their discretion.
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To facilitate future trenching, rock (or oversized material), should not be placed within the
hold-down depth feet from finish grade, the range of foundation excavations, future utilities,
or underground construction unless specifically approved by the governing agency, the
geotechnical consultant, and/or the developer's representative.
If import material is required for grading, representative samples of the materials to be
utilized as compacted fill should be analyzed in the laboratory by the geotechnical
consultant to evaluate It's physical properties and suitability for use onsite. Such testing
should be performed three (3) days prior to importation. If any material other than that
previously tested is encountered during grading, an appropriate analysis ofthis material
should be conducted by the geotechnical consultant as soon as possible.
Approved fill material should be placed in areas prepared to receive fill In near horizontal
layers, that when compacted, should not exceed about 6 to 8 inches in thickness. The
geotechnical consultant may approve thick lifts if testing indicates the grading procedures
are such that adequate compaction is being achieved with lifts of greater thickness. Each
layer should be spread evenly and blended to attain uniformity of material and moisture
suitable for compaction.
Fill layers at a moisture content less than optimum should be watered and mixed, and wet
fill layers should be aerated by scarification, or should be blended with drier material.
Moisture conditioning, blending, and mixing ofthe fill layer should continue until the fill
materials have a uniform moisture content at, or above, optimum moisture.
After each layer has been evenly spread, moisture conditioned, and mixed, it should be
uniformly compacted to a minimum of 90 percent ofthe maximum density as evaluated by
ASTM test designation D-1557, or as othen^/ise recommended by the geotechnical
consultant. Compaction equipment should be adequately sized and should be specifically
designed for soil compaction, or of proven reliability to efficiently achieve the specified
degree of compaction.
Where tests indicate that the density of any layer of fill, or portion thereof, is below the
required relative compaction, or improper moisture Is in evidence, the particular layer or
portion shall be re-worked until the required density and/or moisture content has been
attained. No additional fill shall be placed in an area until the last placed lift of fill has been
tested and found to meet the density and moisture requirements, and is approved by the
geotechnical consultant.
In general, perthe latest adopted version ofthe California Building Code (CBC), fill slopes
should be designed and constructed at a gradient of 2:1 (h:v), or flatter. Compaction of
slopes should be accomplished by over-building a minimum of 3 feet horizontally, and
subsequently trimming back to the design slope configuration. Testing shall be performed
as the fill is elevated to evaluate compaction as the fill core is being developed. Special
efforts may be necessary to attain the specified compaction in the fill slope zone. Final
slope shaping should be performed by trimming and removing loose materials with
The Kevane Company, Inc. , Appendix F
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appropriate equipment. Afinal evaluation of fill slope compaction should be based on
observation and/or testing of the finished slope face. Where compacted fill slopes are
designed steeper than 2:1 (h:v), prior approval from the governing agency, specific
material types, a higher minimum relative compaction, special reinforcement, and special
grading procedures will be recommended.
If an alternative to over-building and cutting back the compacted fill slopes is selected,
then special effort should be made to achieve the required compaction in the outer 10 feet
of each lift of fill by undertaking the following:
1. An extra piece of equipment consisting of a heavy, short-shanked sheepsfoot
should be used to roll (horizontal) parallel to the slopes continuously as fill is
placed. The sheepsfoot roller should also be used to roll perpendicular to the
slopes, and extend out over the slope to provide adequate compaction to the face
of the slope.
2. Loose fill should not be spilled out over the face of the slope as each lift is
compacted. Any loose fill spilled over a previously completed slope face should be
trimmed off or be subject to re-rolling.
5. Field compaction tests will be made in the outer (horizontal) ±2 to ±8 feet of the
slope at appropriate vertical intervals, subsequent to compaction operations.
4. After completion of the slope, the slope face should be shaped with a small tractor
and then re-rolled with a sheepsfoot to achieve compaction to near the slope face.
Subsequent to testing to evaluate compaction, the slopes should be grid-rolled to
achieve compaction to the slope face. Final testing should be used to evaluate
compaction after grid rolling.
5. Where testing indicates less than adequate compaction, the contractor will be
responsible to rip, water, mix, and recompact the slope material as necessary to
achieve compaction. Additional testing should be performed to evaluate
compaction.
SUBDRAIN INSTALLATION
Subdrains should be installed in approved ground in accordance with the approximate
alignment and details indicated by the geotechnical consultant. Subdrain locations or
materials should not be changed or modified without approval of the geotechnical
consultant. The geotechnical consultant may recommend and direct changes in subdrain
line, grade, and drain material in the field, pending exposed conditions. The location of
constructed subdrains, especially the outlets, should be recorded/surveyed bythe project
civil engineer. Drainage at the subdrain outlets should be provided by the project civil
engineer.
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EXCAVATIONS
Excavations and cut slopes should be examined during grading by the geotechnical
consultant. If directed by the geotechnical consultant, further excavations or
overexcavation and refilling of cut areas should be performed, and/or remedial grading of
cut slopes should be performed. When fill-over-cut slopes are to be graded, unless
otherwise approved, the cut portion ofthe slope should be observed bythe geotechnical
consultant prior to placement of materials for construction of the fill portion of the slope.
The geotechnical consultant should observe all cut slopes, and should be notified by the
contractor when excavation of cut slopes commence.
If, during the course of grading, unforeseen adverse or potentially adverse geologic
conditions are encountered, the geotechnical consultant should investigate, evaluate, and
make appropriate recommendations for mitigation ofthese conditions. The need for cut
slope buttressing or stabilizing should be based on in-grading evaluation by the
geotechnical consultant, whether anticipated or not.
Unless otherwise specified In geotechnical and geological report(s), no cut slopes should
be excavated higher or steeper than that allowed by the ordinances of controlling
governmental agencies. Additionally, short-term stability of temporary cut slopes is the
contractor's responsibility.
Erosion control and drainage devices should be designed by the project civil engineer and
should be constructed in compliance with the ordinances ofthe controlling governmental
agencies, and/or In accordance with the recommendations ofthe geotechnical consultant.
COMPLETION
Observation, testing, and consultation by the geotechnical consultant should be
conducted during the grading operations In order to state an opinion that all cut and fill
areas are graded in accordance with the approved project specifications. After completion
of grading, and after the geotechnical consultant has finished observations of the work,
final reports should be submitted, and may be subject to review by the controlling
governmental agencies. No further excavation orfilling should be undertaken without prior
notification of the geotechnical consultant or approved plans.
All finished cut and fill slopes should be protected from erosion and/or be planted in
accordance with the project specifications and/or as recommended by a landscape
architect. Such protection and/or planning should be undertaken as soon as practical after
completion of grading.
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JOB SAFETY
General
At GSI, getting the job done safely is of primary concern. The following is the company's
safety considerations for use by all employees on multi-employer construction sites.
On-ground personnel are at highest risk of injury, and possible fatality, on grading and
construction projects. GSI recognizes that construction activities will vary on each site, and
that site safety Is the prime responsibility of the contractor; however, everyone must be
safety conscious and responsible at all times. To achieve our goal of avoiding accidents,
cooperation between the client, the contractor, and GSI personnel must be maintained.
In an effort to minimize risks associated with geotechnical testing and observation, the
following precautions are to be implemented for the safety of field personnel on grading
and construction projects:
Safety Meetings: GSI field personnel are directed to attend contractor's regularly
scheduled and documented safety meetings.
Safety Vests: Safety vests are provided for, and are to be worn by GSI personnel,
at all times, when they are working in the field.
Safety Flags: Two safety flags are provided to GSI field technicians; one is to be
affixed to the vehicle when on site, the other is to be placed atop the
spoil pile on all test pits.
Flashing Lights: All vehicles stationary in the grading area shall use rotating or flashing
amber beacons, or strobe lights, on the vehicle during all field testing.
While operating a vehicle in the grading area, the emergency flasher
on the vehicle shall be activated.
In the event that the contractor's representative observes any of our personnel not
following the above, we request that it be brought to the attention of our office.
Test Pits Location, Orientation, and Clearance
The technician is responsible for selecting test pit locations. A primary concern should be
the technician's safety. Efforts will be made to coordinate locations with the grading
contractor's authorized representative, and to select locations following or behind the
established traffic pattern, preferably outside of currenttraffic. The contractor's authorized
representative (supen/isor, grade checker, dump man, operator, etc.) should direct
excavation of the pit and safety during the test period. Of paramount concern should be
the soil technician's safety, and obtaining enough tests to represent the fill.
The Kevane Company, Inc. ^ Appendix F
Flle:e:Vwp12V6600V6635a.ruge GeoSoilS, InC. Page 8
Test pits should be excavated so that the spoil pile is placed away from oncoming traffic,
whenever possible. The technician's vehicle Is to be placed next to the test pit, opposite
the spoil pile. This necessitates the fill be maintained in a driveable condition.
Alternatively, the contractor may wish to park a piece of equipment in front of the test
holes, particularly in small fill areas or those with limited access.
A zone of non-encroachment should be established for all test pits. No grading equipment
should enter this zone during the testing procedure. The zone should extend
approximately 50 feet outward from the center of the test pit. This zone is established for
safety and to avoid excessive ground vibration, which typically decreases test results.
When taking slope tests, the technician should park the vehicle directly above or belowthe
test location. If this is not possible, a prominent flag should be placed at the top of the
slope. The contractor's representative should effectively keep all equipment at a safe
operational distance (e.g., 50 feet) away from the slope during this testing.
The technician is directed to withdraw from the active portion ofthe fill as soon as possible
following testing. The technician's vehicle should be parked at the perimeter of the fill in
a highly visible location, well away from the equipment traffic pattern. The contractor
should inform our personnel of all changes to haul roads, cut and fill areas or other factors
that may affect site access and site safety.
In the event that the technician's safety is jeopardized or compromised as a result of the
contractor'sfailureto complywith any ofthe above, the technician Is required, by company
policy, to immediately withdraw and notify his/her supen/isor. The grading contractor's
representative will be contacted in an effort to affect a solution. However, In the Interim,
no further testing will be performed until the situation is rectified. Any fill placed can be
considered unacceptable and subjectto reprocessing, recompaction, or removal.
In the event that the soil technician does not comply with the above or other established
safety guidelines, we request that the contractor bring this to the technician's attention and
notify this office. Effective communication and coordination between the contractor's
representative and the soil technician is strongly encouraged in order to implement the
above safety plan.
Trench and Vertical Excavation
It Is the contractor's responsibility to provide safe access into trenches where compaction
testing Is needed. Our personnel are directed not to enter any excavation or vertical cut
which: 1) is 5 feet or deeper unless shored or laid back; 2) displays any evidence of
instability, has any loose rock or other debris which could fall into the trench; or 3) displays
any other evidence of any unsafe conditions regardless of depth.
All trench excavations or vertical cuts in excess of 5 feet deep, which any person enters,
should be shored or laid back. Trench access should be provided in accordance with
The Kevane Company, Inc. , Appendix F
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Cal/OSHA and/or state and local standards. Our personnel are directed not to enter any
trench by being lowered or "riding down" on the equipment.
If the contractor falls to provide safe access to trenches for compaction testing, our
company policy requires that the soil technician withdraw and notify his/her supen/isor.
The contractor's representative will be contacted in an effort to affect a solution. All backfill
nottested due to safety concerns or other reasons could be subjectto reprocessing and/or
removal.
If GSI personnel become aware of anyone working beneath an unsafe trench wall or
vertical excavation, we have a legal obligation to put the contractor and owner/developer
on notice to Immediately correct the situation. If corrective steps are not taken, GSI then
has an obligation to notify Cal/OSHA and/or the proper controlling authorities.
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Design finish slope
Blanket fill (if recommended by
the geotechnical consultant)
Drainage per design
civil engineer
Typical benching
Typical
benching
(4-foot
minimum)
Bedrock or
approved native
material
Subdrain as
recommended by
geotechnical consultant
4-inch-diameter non-perforated
outlet pipe and backdrain (see
detail Plate F-6). Outlets to be
spaced at 100-foot maximum
intervals and shall extend 2 feet
beyond the face of slope at time
of rough grading completion. At
the completion of rough grading,
the design civil engineer should
provide recommendations to
convey any outlet's discharge to
a suitable conveyance, utilizing a
non-erosive device.
60iS|» TYPICAL STABILIZATION / BUTTRESS FILL DETAIL Plate F-5
, 2-foot ,
minimum
4-inch
minimum—'
pipe
2-Inch
minimum 1
2-fool
minimum
Filter Material: Minimum of 5 cubic feet per lineal foot of pipe or 4 cubic feet per lineal
feet of pipe when placed in square cut trench.
Alternative in Lieu of Filter Materiah Gravel may be encased in approved filter fabric.
Filter fabric shall be Mirafi 140 or equivalent. Filter fabric shall be lapped a minimum of
12 inches in all joints.
Minimum 4-lnch-Diameter Pipe= ABS-ASTM D-2751, SDR 35; or ASTM D-1527 Schedule
40, PVC-ASTM D-3034, SDR 35; or ASTM D-1785 Schedule 40 with a crushing strength
of 1,000 pounds minimum, and a minimum of 8 uniformly-spaced perforations per foot of
pipe. Must be installed with perforations down at bottom of pipe. Provide cap at
upstream end of pipe. Slope at 2 percent to outlet pipe. Outlet pipe to be connected
to subdrain pipe with tee or elbow.
Notes: 1. Trench for outlet pipes to be backfilled and compacted with onsite soil.
2. Backdrains and lateral drains shall be located at elevation of every bench
drain. First drain located at elevation just above lower lot grade. Additional
drains may be required at the discretion of the geotechnical consultant.
Rlter Material shall be of the following
specification or an approved equivalent.
Gravel shall be of the following
specification or an approved equivalent.
Sieve Size Percent Passina Sieve Size Percent Passina
1 inch 100 1)^ inch 100
% inch 90-100 No. 4 50
% inch 40-100 No. 200 8
No. 4 25-40
No. 8 18-33
No. 30 5-15
No. 50 0-7
No. 200 0-3
TYPICAL BUTTRESS SUBDRAIN DETAIL Plate F-6
Toe of slope as shown
on grading plan
Natural slope to
be restored with
compacted fill
Proposed grade
Backcut varies
2-foot minimum
in bedrock or
\ approved
I earth material '•
Bedrock or
approved
native material
Subdrain as recommended by
geotechnical consultant
NOTES:
1. Where the natural slope approaches or exceeds the design slope ratio, special recommendations would be
provided by the geotechnical consultant.
2. The need for and disposition of drains should be evaluated by the geotechnical consultant, based upon
exposed conditions.
FILL OVER NATURAL (SIDEHILL FILL) DETAIL Plate F-7
Cut/fill contact as
shown on grading plan Proposed grade
15-foot minimum or
H/2 where H is—
It I
Subdrain as recommended by
geotechnical consultant
Bedrock or approved
native material
NOTE- The cut portion of the slope should be excavated and evaluated by the geotechnical consultant prior to
construction of the fill portion.
FILL OVER CUT DETAIL Plate F-8
Natural slope
Proposed finish grade
Typical benching
(4-foot minimum)
Compacted stablization fill
Bedrock or other
approved native material
If recommended by the geotechnical
consultant, the remaining cut portion of
the slope may require removal and
replacement with compacted fill.
Subdrain as recommended by
geotechnical consultant
NOTES: 1. Subdrains may be required as specified by the geotechnical consultant.
2 W shall be equipment width (15 feet) for slope heights iess than 25 feet. For slopes greater than
25 feet, W shall be evaluated by the geotechnical consultant. At no time, shall W be less than H/2,
where H is the height of the slope.
STABLIZATION FILL FOR UNSTABLE MATERIAL EXPOSED IN CUT SLOPE DETAIL Plate F-9
Proposed finish grade Natural grade
Bedrock or
approved
native material
Typical benching
(4-foot minimum)
2-foot minimum
key clepth or H/2 If H)30 feet Subdrain as recommended by
geotechnical consultant
NOTES: 1. 15-foot minimum to be maintained from proposed finish slope face to backcut.
2. The need and disposition of drains will be evaluated by the geotechnical consultant based on field conditions.
3. Pad overexcavation and recompaction should be performed if evaluated to be necessary by the
geotechnical consultant.
SKIN FILL OF NATURAL GROUND DETAIL Plate F-10
Reconstruct compacted fill slope at 2:1 or flatter
(may increase or decrease pad area)
Overexcavate and recompact
replacement fill
Back-cut varies
Natural grade
Proposed
finish grade
Avoid and/or clean up
spillage of materials on
the natural slope
2-foot minimum I key width
Bedrock or approved
native material
Typical benching
(4-foot minimum)
Subdrain as recommended by
geotechnical consultant
NOTES: 1. Subdrain and key width requirements will be evaluated based on exposed subsurface conditions and
thickness of overburden.
2. Pad overexcavation and recompaction should be performed if evaluated necessary by the geotechnical
consultant.
DAYLIGHT CUT LOT DETAIL Plate F-11
Natural grade
Proposed pad grade
Bedrock or
approved native
material
Typical benching
CUT LOT OR MATERIAL-TYPE TRANSITION
Proposed pad grade
Natural grade
.^>> Subgrade at 2 percent gradient, draining toward street
3- to 7-foot minimum* —'
overexcavate and recompact
per text of report
Bedrock or
approved native
Typical benching material
(4-foot minimum)
* Deeper overexcavation may be
recommended by the geotechnical
consultant in steep cut-fill transition
areas, such that the underlying
topography is no steeper than 31 (H:V)
CUT-FILL LOT (DAYLIGHT TRANSITION)
TRANSITION LOT DETAILS Plate F-12
MARVIEW
NOT TO SCALE
SEE NOTES
4-inch perforated
subdrain pipe
(transverse)
Direction
of drainage
4-inch perforated
subdrain pipe
(longitudinal)
2-inch-thick
sand layer
CROSS SECTION VIEW
NOT TO SCALE
SEE NOTES
Coping
Pooi encapsulated in 5-foot
thickness of sand
Vapor retarder
B
6-inch-thick gravel layer
4-inch perforated subdrain pipe
Coping
I I 5 feet
Outlet per design
civil engineer
H/3
Zone of
Distress
6-inch-thick-
gravel layer
Pool
>
Gravity-flow nonperforated-
subdrain pipe
''Concrete
cut-off wall
2-inch-thick sand layer
Vapor retarder
Perforated subdrain pipe
NOTES:
1
2.
3.
6-inch-thick, clean gravel {% to 1)^ inch) sub-base encapsulated in Mirafi 140N or equivalent, underlain by
a 15-mil vapor retarder, with 4-inch-diameter perforated pipe longitudinal connected to 4-inch-diameter
perforated pipe transverse. Connect transverse pipe to 4-inch-diameter nonperforated pipe at low point
and outlet or to sump pump area.
Pools on fiiis thicker than 20 feet should be constructed on deep foundations.- otherwise, distress (tilting,
cracking, etc.) should be expected.
Design does not apply to infinity-edge pools/spas.
TYPICAL POOL/SPA DETAIL Plate F-17
SiDE VIEW
Test pit
TOP VIEW
Flag
-50 feet
r P"® r- Test pit
Vehicle
50 feet-
-100 feet-
TEST PIT SAFETY DIAGRAM Plate F-20
4'
290-
UJ
PROPOSED GRADE I5:1(h:v) SLOPE
wrm GEOGRID/RBNFORCEMENT PER N&M (2009)
TP-6 (N&M,2009)
PROJECTED
PROPOSEO GRADE-
EXISVNG GRADE
PA
PARCEL 4—-
TP-1 (GSI,1989)
PROJECTED
260-
EL CAUINO REAL
230-
-290
EXISVNG GRADE
PA
J Qvop
^JO' KEYWAY
I sa PER NScU(2009)
50 60
B
~1 1
90 120
DISTANCE (FEET)
/V75T
ZP^
150 180
-260 S
Uj
-2J0
2/0 236
TP-2 (GSI,1989)
PROPOSED GRADE
290-
PROPOSED GRADE 1.5:1(h:v) SLOPE
WfTH GEOGRID/REINFORCEUENT PER NAU (2009)
TP-4 (GSI,1989)^
PROJECTED
I
5 260 H
UJ
uj
•EL CAUINO REAL-
EXISVNG GRADE-
PA
EXISVNG GRADE B'
Afu
PA
230-
Tsa ^ JO' KEYWAY PER N&U(2009)
BACKCUT PER N&U(2009)
Tsa
30 60
JO 0
n I
90 120
DISTANCE (FEET)
GRAPHIC SCALE
15 JO 60
/50
BACKCUT PER
N&Mf2009)
30' KEYWAY PER NAM(2009)
180 210 240 252
720
r = 30'
Afu
Qvop
GSI LEGEND
— ARVnOAL FILL - UNDOCUMENTED (EXISVNG)
- QUATERNARY VERY OLD PARALIC DEPOSITS
Tsa — TERVARY SANVAGO FORMAVON
'*—^ — APPROXIMATE LOCAVON OF GEOLOQC CONTACT
.^ir — BEDDING ATTITUDE, WITH APPARENT DIP IN DEGREES
....r — BEDDING ATVTUDE. WITH APPARENT DIP IN DEGREES
ALL LOCATIONS ARE APPROXIMATE
This document or eflle Is not a part of the Construction
Documents and should not to relied upon as being an
accurate depiction of design.
GEOLOGIC CROSS SECTIONS
A-A; B-B' Plate 2
wa 6$53J^ DATE.. 04/14 SCALE f