HomeMy WebLinkAboutSUP 06-12; ROBERTSON RANCH HABITAT CORRIDOR; REPORT OF MASS GRADING; 2008-07-1600
Geotechnical • Geologic Coastal • Environmental
5741'Palmer Way • Carlsbad, California 92010 (760)438-3155 FAX(760)93-l-0'915
July 16, 2008
W.O; 5247-132-SC
Robertson Family trust'
do SeaBourne Development Co.
P.O. Box 4659
Carlsbad, California 92018-4659
Attention: Mr. Ken Cablay -
Subject: Report of Mass Gradihg Planning Area ii', Robertson Ranch Habitat
Corridor and Widening of El Camino Real at Cannon Road, Robertson Ranch
West, Carlsbad, San Diego County, California 92010,' City .of Carlsbad
Planning Department Application No: SUP 06-1 2/HDP 06-04
Dear Mr. Cablay: -
This report presents a summary of the geotechnical testing, and: observation, services
provided by GeoSoils, Inc. (GSI) during the mass grading phase bLdevlopment for
Planning Area -.11 (PA-11). It, is GSI's understanding that the- purp6se of grading was to
prepare a relatiiely level "super pad" for the future construction of a commercial/retail
site on PA-1 1, a habitat corridor located east of PA-11, and the-future widening of
El Camino Real with associated infrastructure Earthwork commenced on, or about April
.7, 2008,arid was generally completed on June 9, 2008. The mass grading consisted of
sheet grading PA-1 1 to the design grades shown on the'approved gradiri plan, by O'Day
Consulting (OC, 2006). The approximate elevations of field densitytest locations iñdiáated
in Table are based on limited staking and field measurementh based bn the approved
grading plan (OC, 2006). Currently, it is our understanding that future development plans
of PA-1 1 are anticipated to be a commercial/retail site and associated infrastructure
Therefore, supplemental geotechnical recommendations should be provided when
construction and precise grading plans have béén developed, including updated
foundation, slab, retaining wall, flatwork,etc.,design criteria. Survey of line and grade was
performed by others, and not performed by GSI.
EXISTING ADJOINING ROADWAY FILL
Existing adjoining roadway fill was utilized during mass grading for the future widening of
El Camino Real As a result of the existing offsite improvements and underground utilities
along El Camino Real, complete removals were not feasible in this arear Therefore, the
existing road fill was benched,, in acordance.withthe approved report byGSI (2007b).
In addition, as requested by the client, the existing road fill on the SDG&E access road was
moisture conditioned, etc., during mass grading. Some of the compacted fill reported
herein was placed on those existing roadway fills.
ENGINEERING GEOLOGY
The geologic conditions exposed during the process of grading for the current phase of
development were regularly observed by a representative from our firm. The geologic
conditions encountered generally were as anticipated and presented in the preliminary
geotechnical reports (see the Appendix, References). Supplemental descriptions are
provided below.
Earth Materials
Artificial Fill-Non Structural (Map Symbol - Afn)
The non-structural artificial fill generally consists of a silty to clayey sand and sandy clay
and is located around the SDG&E multi-wood poles and anchors (see Plates 1 and 2).
Thickness of the material is approximately ±9 to ±19 feet. The non-structural artificial
fill should be removed, moisture conditioned, and recompacted, should future
settlement-sensitive improvements be proposed within its influence.
Artificial Fill-Roadway (Map Symbol - Afr)
The roadway artificial fill generally consists of a silty to clayey sand and sandy clay and is
located on the SDG&E access road and along El Camino Real. Thickness of the material
on the SDG&E access road appears to be approximately ±3 to ±4 feet. Thickness of the
material along El Camino Real appears to be approximately ±8 to ± 15 feet. The suitability
of the roadway fill for its intended use should be satisfactory, from a geotechnical
viewpoint, assuming all interested/affected parties are informed that regular maintenance
and care, as with all roadways, will be required.
Artificial Fill (Map Symbol - Af)
The artificial fill generally consists of a light brown to dark brown, silty to clayey sand and
sandy clay. Thickness of the material placed under the preview of this report is up to
±321/2 feet. Artificial fill placed under the preview of this report is considered suitable for
its current intended use, again, assuming regular maintenance and care.
Colluvium (Not Mapped)
Colluvium is on the order of 2 to 3 feet thick, consists of silty to clayey sand and sandy
clay, and was left-in-place at the top of the two cut slopes on PA-1 1. These soils are
typically dry to moist, loose to medium dense (sands), stiff (clays), and porous. Colluvium
is not considered suitable for support of future settlement-sensitive improvements, unless
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these soils are removed, moisture conditioned, and placed as compacted fill. Dessication
cracks in colluvial soils are visible at the surface in some areas of the cut slopes on PA-1 1.
As discussed herein, when precise grading plans have been developed, these cut slopes
should be re-evaluated and supplemental recommendations (i.e., removal, replacement
as a stabilization fill, debris impact walls, etc.) will be provided, as warranted.
Alluvium (Map Symbol - Qal)
Alluvial sediments occur within a distinct depositional environment onsite, termed valley
alluvium, deposited within the larger, broad flood plains located along the west and south
sides of the project. Where encountered, alluvial sediments consist of sandy clay and
clayey/silty sand. Clayey sands are typically loose to medium dense, while sandy clays
are stiff. Alluvium ranges from generally damp to wet above the local groundwater table,
to saturated just above and below the groundwater table. As a result of the presence of
groundwater, alluvial removals were limited in depth. Therefore, as provided for in the
approved report (GSI, 2007b), saturated left-in-place alluvial soils (see Plates 1 and 2),
will require settlement monitoring and site specific foundation design, should future
settlement-sensitive improvements be proposed in areas underlain by alluvium left in
place, or within its influence. At this time' it is GSl's understanding that this area will remain
as a habitat corridor and no settlement-sensitive improvements are planned.
Terrace Deposits (Map Symbol - Qt)
Mid-to late-Pleistocene sediments, termed terrace deposits, were encountered onsite and
vary from silty sand to sandy/silty clay. They are typically reddish brown to brown and olive
brown, slightly moist to moist, and medium dense/stiff. Terrace deposits are generally
considered suitable for the support of structures and engineered fill. However, due to the
non-uniform and different soil types in contact with each other, creating non-uniformity,
overexcavation is recommended if settlement-sensitive or expansive-sensitive
improvements (i.e., buildings, concrete decks, etc.) are proposed within this area.
Geologic Structure
Our review and observations during grading indicates that jointing within the terrace
deposits generally strikes N45E to N79W. Joints are typically steeply dipping (generally
in excess of 40 degrees), and are generally inclined to the east and west. Bedding is
generally dipping in a northerly and southerly direction. Beds are typically sub-horizontal
to gently dipping (generally less than 15 degrees), and are generally inclined to the
southwest, basically neutral to cut slopes, where exposed, although local crenulations
exhibit some out of slope components. The contact between the alluvium overlying the
Pleistocene-age terrace deposits is unconformable in nature, as in much of California,
when many ancient swales and channels were deeply incised during the last major pluvial
epoch, this occurring approximately 12,000 to 18,000 years ago (Dietrich and Dorn, 1984;
Shlemon, et al., 1987).
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Groundwater
Groundwater was encountered during grading at elevations ranging from about
32 to 49 feet Mean Sea Level (MSL) in the valley alluvial material (Map Symbol - Qal).
Generally, and based upon the available data, regional groundwater is not expected to be
a major factor in the development of the site. However, perched groundwater may occur
within the fill or along zones of contrasting permeabilities (i.e., differing fill lifts or along
bedding planes and bedrock joints/discontinuities, etc.), due to migration from onsite,
offsite, or adjacent drainage areas, and during and/or after periods of above normal or
heavy precipitation or irrigation. Thus, perched groundwater conditions may occur in the
future, after development, and should be anticipated. These observations reflect site
conditions at the completion of grading and do not preclude changes in local groundwater
conditions in the future. Should such conditions become apparent within the project in the
future, additional recommendations for mitigation may be provided upon request. This
potential would need to be disclosed to all interested/affected parties.
Canyon Subdrains
Canyon subdrains were installed in general accordance with the approved
recommendations provided by this office (GSI, 2007b), and/or as recommended based on
field conditions exposed during grading. The approximate locations of subdrains and
outlets within the subject area are shown on the Field Density Test Location Maps included
in this report. Subdrain outlets should be reviewed by the project design civil engineer, so
that flow and erosion are properly mitigated.
EARTHWORK CONSTRUCTION
Earthwork operations have been completed in general accordance with the approved
report for the site (GSI, 2007b), City of Carlsbad grading ordinance, and the guidelines
provided in the field by this office. Observations during grading included removals along
with general grading procedures and placement of compacted fills by the contractor.
Preparation of Existing Ground
Prior to grading, the major surficial vegetation was stripped and hauled offsite.
Removals, consisting of topsoil/colluvium, alluvium, and near-surface weathered
terrace deposits, were performed to the minimum depths and lateral extent, or
greater, as recommended in the approved referenced report by GSI (2007b). The
approximate removal limits are indicated on Plates 1, 2, and 3.
Due to the existing offsite improvements along El Camino Real, and the SDG&E
access road, complete removals were not feasible in these areas. Therefore, the
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existing road fill was benched in accordance with the approved report by GSI
(2007b).
Subsequent to the above removals, the exposed subsoils were scarified to a depth
of about 12 inches, moisture conditioned as necessary to at least optimum moisture
content, then compacted to a minimum relative compaction of 90 percent of the
laboratory standard.
Fills placed on sloping surfaces steeper than 5:1 (horizontal to vertical [h:v]), as
indicated by pre-existing topography, were keyed and benched into competent
terrace deposits.
5. All processing of original ground was observed by a representative of GSI.
Fill Placement
Fill, consisting of native soils, was placed in 6-to 8-inch lifts, watered, and mixed to achieve
at least optimum moisture conditions. The material was then compacted, using earth
moving equipment, to a minimum relative compaction of 90 percent of the laboratory
standard. It should be noted that materials greater than 12 inches in diameter were
routinely placed below 10 feet from finish grade. However, oversized materials may not
be precluded from occurring, and/or excavation difficulties may be encountered at finish
grade. Thus, the potential for excavation difficulties and oversized materials should be
disclosed to all affected/interested parties.
Transitions
During mass grading of the site, a designed cut/fill transition, as indicated on the grading
plans by OC (2006), was graded without any additional mitigation, such as overexcavation
of the cut, since the location of settlement-sensitive structures was not known. Once
precise grading plans have been formulated, GSI should review such plans in order to
provide recommendations for overexcavation, as warranted, in light of the proposed
development.
Slopes
Fill Slopes
Graded 2:1 (h:v) slopes constructed under the purview of this report should perform
satisfactorily with respect to gross and surficial stability under normal conditions of care,
maintenance, and rainfall (semi-arid). Fill slopes, constructed under the purview of this
report, were provided with a basal bench, or keyway, excavated into suitable earth material
in general accordance with the approved GSI recommendations (GSI, 2007b).
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Cut Slopes
Cut slopes were excavated in general accordance with the approved GSI
recommendations (GSI, 2007b), at an inclination of 2:1 (h:v), or flatter, and exposed
colluvium and terrace deposits earth material(s). The exposed material within this cut
slope was highly fractured, and locally exhibited out of slope crenulations. Therefore,
above normal maintenance and care should be expected on these cut slopes. The
maximum cut slope is on the order of 30 feet in height. When precise grading plans have
been developed, these cut slopes should be re-evaluated and supplemental
recommendations will be provided, as warranted. GSI was advised by the client that future
development plans will consist of a relatively flat-lying pad that will eliminate these two
existing cut slopes. Although unlikely, future design may necessitate stabilization of the
cut slopes, depending on development plans.
Temporary Slopes
Temporary construction slopes may be constructed at a gradient of 1:1 (h:v), or flatter, in
compacted fill and/or terrace deposits (provided adverse conditions [including
groundwater] are not present, as evaluated by GSI, prior to workers entering trenches).
Utility trenches may be excavated in accordance with guidelines presented in Title 8 of the
California Code of Regulations for Excavation, Trenches, and Earthwork, with respect to
"Type B" soil (compacted fill and/or native material), provided groundwater is not present.
Construction materials and/or stockpiled soil should not be stored within 5 feet from the
top of any temporary slope. Temporary/permanent provisions should be made to direct
any potential runoff away from the top of temporary slopes. If groundwater is present,
"Type B" may not be sufficient and field conditions should be evaluated and additional
recommendations be provided by the geotechnical engineer, as warranted.
Natural Slopes
Offsite natural slopes surrounding the subject site generally consist of low to moderately
steep terrain, except near portions of El Camino Real, where they become near-vertical.
While indications of significant mass wasting phenomena on the site were not observed
during mass grading, review of available data (Tan and Kennedy, 1996; Tan and
Giffen, 1995; Wilson, 1972), and review of aerial photographs (United States Department
of Agriculture, 1953), indicates that the possibility of localized surficial instability exists on
natural slopes which descend near the property. In addition, the site area has been
mapped (Tan and Giffen, 1995) as being marginally susceptible to landslides in the lower
elevation alluvial valleys and generally susceptible to landslide hazards in the upper
elevations. Surrounding natural slopes may be subject to creep, possible surficial failures,
and gullying. Such surficial failures generally occur along canyon areas and/or along the
steeper slopes and typically involve the outer 1 to 4 feet of the slope surface. The more
granular soils (i.e., clayey sands, silty sands) with low plasticity are more susceptible.
During heavy rains, these creep-affected rock materials are prone to downhill movement
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in the form of surficial failures. Therefore, where natural slopes and/or existing drainages
intersect future development areas, mitigation in the form of debris catchment devices (i.e.,
setbacks, catchment basins, debris fences, debris walls, etc.) may be recommended,
depending upon the final development plans and proposed use. The locations of such
recommended devices should be provided at the precise grading plan review stage, as
warranted.
FIELD TESTING
Field density tests were performed using nuclear (densometer) ASTM test
methods D 2922 and D 3017 and sand-cone ASTM test method ASTM D 1556. The
test results taken during grading are presented in the attached Table 1, and the
locations of the tests taken during grading are presented on Plates 1, 2,. 3, and 4.
Field density tests were taken at periodic-intervals and random locations to check
the compactive effort provided by the contractor. Where test results indicated less
than optimum moisture content, or less than 90 percent relative compaction in fills,
the contractor was notified and the area was reworked until retesting indicated at
least optimum moisture and a minimum relative compaction of 90 percent were
attained. Based upon the grading operations observed, the test results presented
herein are considered representative of the compacted fill.
Visual classification of the soils in the field was the basis for determining which
maximum density value to use for a given density test.
LABORATORY TESTING -
Maximum Density Testing
The laboratory maximum dry density and optimum moisture content for the major soil
types within this construction phase were determined according to test method
ASTM D 1557. The following table presents the results:
TYPE...:: DESCRIRTION..
MAXIMUM DENSITY
.. (PF . .,...
MOISTURE CONTENT.
11 .PERCENT..c...
A SANDY CLAY, Reddish Brown 118.0 13.5
B CLAYEY SAND, Brown 128.0 10.0
C CLAYEY SAND, Brown Gray 124.0 11.5
D CLAYEY SAND, Dark Gray 125.0 11.0
E SILTY CLAY, Greenish Gray 102.0 21.5
F CLAYEY SAND, Light Brown 122.0 12.5
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Expansion Index
Expansive soil conditions have been evaluated in the general area of the site.
Representative samples of the soils exposed at finish grades will need to be recovered for
Expansion Index (E.I.) testing at the conclusion of precise grading. Based on the test
results obtained, the expansive potentials of the soils within the subject lots are anticipated
to be classified as high to very high (i.e., high to very high expansive potentials 90 to
>130). To reiterate, additional expansion testing will need to be conducted at the
conclusion of precise grading.
Atterberg Limits
Tests were performed on soils exhibiting expansion potentials greater than very low(i.e.,
E.I. above 20), per 1997 UBC requirements, to evaluate the liquid limit, plastic limit, and
plasticity index in general accordance with ASTM D 4318. The test results are presented
below. Once again, additional Atterberg Limits testing will-need to be conducted at the
conclusion of precise grading
LOCATION . LIQUID LIMIT PLASTIC LIMIT F PLASTICITY INDEX
I Super Pad Area 54 I 20 I 34
Sulfate/Corrosion Testing
GSI previously conducted sampling of onsite materials for soil corrosivity on the subject
project (GSI, 2007b). Laboratory test results were completed by Schiff & Associates
(consulting corrosion engineers). The testing included evaluation of pH, soluble sulfates,
and saturated resistivity. Representative samples of the soils exposed at finish grades will
need to be recovered for sulfate/corrosion testing at the conclusion of precise grading.
Test results indicate that the soil presents a negligible sulfate exposure to concrete, in
accordance with Table 19-A-4 of the Uniform Building Code/California Building Code
([UBC/CBC], International Conference of Building Officials [lCBOJ, 1997 and 2001;
California Building Standards Commission [CBSC], 2007); and further results indicate the
soils are severely corrosive to ferrous metals, etc., based on saturated resistivity. Site soils
are considered to be moderately alkaline with regards to acidity/alkalinity. A corrosion
specialist should be consulted for the appropriate mitigation recommendations, as needed.
Once again, additional corrosion testing will need to be conducted at the conclusion of
precise grading.
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PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS
General
Preliminary conclusions and recommendation are provided in our referenced report (GSI,
2007b). However, for convenience, the previous preliminary conclusions and
recommendation are reproduced below and modified as appropriate, based on current
standards and/or conditions. Currently, it is our understanding that future development
plan of PA-1 1 is anticipated to be a commercial/retail site with associated infrastructure.
Therefore, supplemental geotechnical recommendations should be provided when
construction plans have been formulated.
As-Built Conditions
As-built soil conditions to be considered in foundation design and construction are as
follows:
GSl's review, field work, and laboratory testing indicates that onsite soils have a high
to very high expansion potential ([.1. greater than 90), and a plasticity index (P.1.)
greater than 35.
As-built fill thicknesses range from approximately 3 to 191/2 feet for areas with left
in place saturated alluvium, and approximately 0 to 321/2 feet thick in the terrace
deposits area. Roadway fill may range up to about 15 feet thick, and was placed on
fill under the purview of others.
Non-structural artificial fill is located around the SDG&E multi-wood poles and
anchors (see Plates 1 and 2). Thickness of the material is approximately ±9 to
±19 feet. The non-structural artificial fill should be removed, moisture conditioned,
and recompacted, should future settlement-sensitive improvements be proposed
within its influence.
As a result of the presence of groundwater, alluvial removals were limited in depth.
Therefore, as provided for in the approved report (GSI, 2007b), saturated left-in-place
alluvial soils (see Plates 1 and 2), will require settlement monitoring and site specific
foundation design, should future settlement-sensitive improvements be proposed in
areas underlain by alluvium left in place, or within its influence. At this time, it is
GSI's understanding that this area will remain as a habitat corridor and no
settlement-sensitive improvements are planned or proposed. Thus, settlement
monitoring does not appear necessary, at this time.
When precise grading plans have been formulated, the cut slopes (see Plates 1 and
2) should be evaluated and supplemental recommendations will be provided, as
warranted. Future design may necessitate cut slope stabilization, or other mitigation
depending on development plans.
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A design cut/fill transition occurs between the artificial fill compacted under the
purview of this report and the terrace deposits (see Plates 1 and 2). In order to
provide for the uniform support of structures, on a preliminary basis, a minimum
5-foot thick fill blanket is recommended for building pads containing plan transitions.
Any cut portion of the pad for the structure should be over excavated a
minimum 5 feet below finish pad grade. Areas with fills less than 5 feet should be
overexcavated in order to provide the minimum fill thickness. Maximum to minimum
fill thickness within a given building footprint should not exceed ratio of 3:1. As such,
deeper over excavation will be necessary for fill areas with maximum fills in' excess
of approximately 15 feet. Overexcavation is also recommended for cut pads
exposing claystones and/or heterogenous material types (i.e., sand/clay).
Recommended overexcavation depths should be determined based on final
development and precise grading plans.
Owing to the conditions outlined herein, the use of an engineered paving mat (such
as Mirafi HP 570) for the, paved portions of the widening of El Camino Real should-
be considered. The use of an engineered paving mat may be considered to reduce
and mitigate future reflective cracking. The use of such mitigative products may
extend the life of the pavement and ultimately lower associated repairs and
maintenance cost. The pavement section and engineered paving mat should be
evaluated during the preparation of the pavement design report for El Camino Real.
Preliminary Foundation Design
Our review, field work, and laboratory testing within the general area indicates that onsite
soils may have a high to very high expansion potential. The preliminary recommendations
for foundation design and construction are presented in GSI's previous report (GSI, 2007b)
are reproduced below. Final foundation recommendations should be provided at the
conclusion of precise grading, and based on laboratory testing of fill materials exposed at
finish grade.
Bearing Value
The foundation systems should be designed and constructed in accordance with
guidelines presented in the latest approved edition of the UBC/CBC (lCBO, 1997 and
2001; CBSC, 2007).
An allowable bearing value of 2,000 pounds per square foot (psf) may be used for
the design of continuous footings at least 12 inches wide and 12 inches deep, and
column footings at least 24 inches square and 24 inches deep, connected by a
grade beam in at least one direction. This value may be increased by 20 percent for
each additional 12 inches in depth to a maximum of 3,000 psf. No increase in
bearing value is recommended for increased footing width. The allowable bearing
pressure may be increased by one-third under the effects of temporaryloading, such
as seismic or wind loads.
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Lateral Pressure
For lateral sliding resistance, a 0.30 coefficient of friction may be utilized for a
concrete to soil contact when multiplied by the dead load.
Passive earth pressure may be computed as an equivalent fluid having a density of
1' 225 pounds per cubic foot (pcf) with a maximum earth pressure of 2,250 psf.
When combining passive pressure and frictional resistance, the passive pressure
component should be reduced by one-third.
Construction
The following preliminary foundation construction recommendations are presented as a
minimum criteria from a soils engineering standpoint. The onsite soils expansion
potentials generally range from high ([.1. 91 to 130) to very high (E.l. >130) range.
Conventional foundation systems are not recommended for high to very highly expansive
soil conditions or where alluvial soil is left in-place (see Plates 1 and 2). Post-tension slab
or mat foundations may be used for all soil conditions.
Recommendations by the project's design-structural engineer or architect, which may.
exceed the soils engineer's recommendations, should take precedence over the
following minimum requirements. Final foundation design will be provided based on the
expansion potential of the near-surface soils encountered during precise grading, as well
as differential settlement potential. Preliminary foundation recommendations are presented
below.
POST-TENSIONED SLAB DESIGN
In order to mitigate expansive soil conditions, the structures may be supported by post-
tensioned slab foundations.
n r I
The information and recommendations presented in this section are not meant to
supersede design by a registered structural engineer or civil engineer familiar with
post-tensioned slab design or corrosion engineering consultant. Upon request, GSI
could provide additional data/consultation regarding. soil parameters as related to
post-tensioned slab design during grading. The post-tensioned slabs should be designed
in accordance with the Post-Tensioning Institute (P11) Method. Alternatives to the PTI
method may be used if equivalent systems can be proposed which accommodate the
angular distortions, expansion potential and settlement noted for this site.
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- PôST-TEfSI9N FObAToN 4
'.. . EXPANSiON HtGH.TO\ERY'HIGHLY
'gOTENTIAL 'V E-XPANSi'/EE.i. 91
em center lift , . 6.0 feet
em edge lift " 4.5 feet
y center lift . 4.5 inches
Yrn edge lift 1.6 inch
Bearing Value(' 1,000 psf
-. Lateral Pressure 225 psf
Subgrade Modulus (k) 50 pci/inch
Perimeter Footing Embedment(') . 30 inches
V(t) Internal bearing values within the perimeter of the post-tension slab may be increased
to 2,000 psf for a minimum embedthent of 12 inches, then by 20 percent for each
additional foot of embedment to a maximum of 3,000 psf.
(2) As measured below the lowest adjacent compacted subgrade surface.
Note: The use of open bottomed raised planters adjacent to foundations will require more
onerous design parameters.
Post-tenéioned slabs should have sufficient stiffness to resist excessive bending due to
non-uniform swell and shrinkage of subgrade soils. The differential movement can occur
at the corner, edge, or center,of slab. The potential for differentialuplift can be evaluated
using the 1997 UBC Section 1816, based on design specifications of the PTI. The
following table presents suggestedminimurn coefficients to be used in the PTI. design
method.
Thornthwaite Moisture Index 720 inches/year
Correction Factor for Irrigation . 20 inches/year
Depth to Constant Soil Suction 7 feet
Constant Soil Suction (pf) 3.6
The coefficients are considered minimums and may not be adequate to represent worst
case conditions such as adverse drainage and/or improper landscaping and maintenance
The above parameters are applicable provided positive drainage is maintained away from
structures, for a distance of at least 5 feet Therefore, it is important that, information
regarding drainage, site L maintenance, settlements, and effects of expansive soils be
passed on to future owners and/or interestedartis.
Based on the above parameters, design values were obtained from figures or, tables of the
1997 UBC Section 1816 and presented in Table 1 These values may not be appropriate
to account for on differential settlement of the slab due to other factors (i.e., fill
settlement). If a 6tiffer slab is desired, higher values of ym maybe warranted. However the
slab thickness'shoüld be at least 6-inches thick. -
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Subgrade Preparation
The subgrade material should be compacted to a minimum 90 percent of the maximum
laboratory dry density, in view of their expansive potential. Prior to placement of concrete,
the subgrade soils should be moisture conditioned in accordance with the following
discussion.
Perimeter Footings and Pre-Wetting
From a soil expansion/shrinkage standpoint, afairly common contributing factor to distress
of structures using post-tensioned slabs is a significant fluctuation in the moisture content
of soils underlying the perimeter of the slab, compared to the center, causing a "dishing"
or "arching" of the slabs. To mitigate this possible phenomenon, a combination of soil
pre-wetting and construction of a perimeter cut-off wall grade beam should be employed.
Deepened footings/edges around the slab perimeter must be used to minimize surface
moisture migration beneath the slab. Embedment depths are presented in the above table
for various soil expansion conditions. The bottom of the deepened footing/edge should
be designed to resist tension, using cable or reinforcement per the structural engineer.
Slab subgrade should possess above optimum moisture content of at least 5 percent for
highly to very highly expansive soils to a depth of 30 inches. Pre-wetting of the slab
subgrade soil prior to placement of steel and concrete will likely be recommended and
necessary, in order to achieve optimum moisture conditions. Soil moisture contents
should be evaluated at least 72 hours prior to pouring concrete. If pre-wetting of the slab
subgrade is completed priorto footing excavation, the pad area may require period wetting
in order to keep to soil from drying out.
Mat Foundation Design/Construction
As an alternative to post-tensioned design, and in order to mitigate expansive soil
conditions, the structure may be supported by a mat slab foundation. The structural mat
foundation should have a double mat of steel (minimum No. 4 reinforcing bars located at
12 inches on center each way - top and bottom), and a minimum thickness of 12 inches.
A thickened edge (30 inches below the lowest adjacent grade) should be provided across
large or wide entrances. Mats may be designed by Section 1815 (Div. Ill) of the UBC/CBC
(ICBO, 1997 and 2001; CBSC, 2007) methods using an effective P.I. of 45.
Mat slabs may be designed for a modulus of subgrade reaction (Ks) of 50 pounds per
cubic inch (pci) when placed on compacted expansive soils (E. I. up to 130). The following
section of this report provides supplemental recommendations for under-slab soil moisture
transmission mitigation. The slab subgrade moisture content should be at least 4 to
5 percent above the soil's optimum moisture content to a depth as specified in the
pervious section of this report.
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Subgrade Preparation
Clay subgrade materials should be compacted to a minimum of 90 percent of the
maximum laboratory dry density. Prior to placement of concrete, the slab subgrade
moisture content should possess above optimum moisture content of at least 5 percent
for highly to very highly expansive soils, to a depth of 30 inches. This should be evaluated
by our field representative prior to vapor retarder placement, and prior to and within
72 hours of the concrete pour. Alternative methods, including sealing the subgrade
surface with select sand/base and periodic moisture conditioning, may also be considered,
as long as the minimum recommended soil moisture contents are achieved. Lime
treatment of the soil subgrade may also be considered; however, this will require additional
geotechnical analysis.
FLOOR SLAB DESIGN RECOMMENDATIONS
General
Concrete slab-on-grade floor construction is anticipated. The following are presented as
minimum design parameters for the slab, but they are in no way intended to supercede
design by the structural engineer. Design parameters do not account for concentrated
loads (e.g., fork lifts, heavy rack loads, other machinery, etc.) and/or the use of freezers or
heating boxes.
These recommendations are meant as minimums. The project architect and/or structural
engineer should review and verify that the minimum recommendations presented herein
are considered adequate with respect to anticipated uses.
Light Load Floor Slabs
The slabs in areas that will receive relatively light live loads (i.e., office space, less than
50 psf) should be a minimum of 6 inches thick-and be reinforced with No. 3 reinforcing bar
on 18 inch centers in two horizontally perpendicular directions. Reinforcing should be
properly supported to ensure placement near the vertical midpoint of the slab. "Hooking"
of the reinforcement is not considered an acceptable method of positioning the steel.
The project structural engineer should consider the use of transverse and longitudinal
control joints to help control slab cracking due to concrete shrinkage or expansion. Two
of the best ways to control this movement are: 1) add a sufficient amount of reinforcing
steel to increase the tensile strength of the slab; and 2) provide an adequate amount of
control and/or expansion joints to accommodate anticipated concrete shrinkage and
expansion. Transverse and longitudinal crack control joints should be spaced no more
than 12 feet on center and constructed to a minimum depth of T/4, where "1" equals the
slab thickness in inches.
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Heavy Load Floor Slabs
The project structural engineer should design the slabs in areas subject to high loads
(machinery, forklifts, storage racks, etc.). The modulus of subgrade reaction (k-value) may
be used in the design of the floor slab supporting heavy truck traffic, fork lifts, machine
foundations, and heavy storage areas. A k-value (modulus of subgrade reaction) of
50 pounds per square inch per inch (pci) would be prudent to utilize for preliminary slab
design. An R-value test and/or plate load test may be used to verify the k-value on
near-surface fill soils.
Concrete slabs should minimally be at least 6 inches thick, and reinforced with No. 4
reinforcing bars placed 12 inches on center in two horizontally perpendicular directions.
Selection of slab thickness compatibility with anticipated loads should be provided by the
structural engineer.
Transverse and longitudinal crack control joints should be spaced no more than 14 feet
on center and constructed to a minimum depth of T/4. The use of expansion joints in the
slab should be considered. Concrete used in slab construction should have a maximum
water/cement ratio of 0.5. Spacing of expansion or crack control joints should be modified
based on the footprint of the area to be heavily loaded.
Conventional foundations and slabs-on-grade may heave and cause offsets along
concrete floor cracks due to differential shrink/swell of highly expansive soils. This may
limit or affect planned uses such as warehouses, storage racks, forklift operation, etc.
Subgrade Preparation
Clay subgrade material should be compacted to a minimum of 90 percent of the maximum
laboratory dry density. Prior to placement of concrete, the slab subgrade moisture content
should possess above optimum moisture content of at least 5 percent for highly to very
highly expansive soils to a depth of 30 inches. This should be verified by our field
representative prior to visqueen placement and prior to and within 72 hours of the concrete
pour. Alternative methods, including sealing the subgrade surface with select sand/base
and periodic moisture conditioning, may also be considered, as long as the minimum
recommended soil moisture contents are achieved. As discussed in a previous section,
lime treatment of the soil subgrade may also be considered.
UNDERSLAB TREATMENT/SOIL MOISTURE CONSIDERATIONS
GSl has evaluated the potential for vapor or water transmission through slabs, in light of
typical floor coverings and improvements. Please note that slab moisture emission rates,
range from about 2 to 27 lbs/24 hours/1,000 square feet from atypical slab (Kanare, 2005),
while floor covering manufacturers generally recommend about 3 lbs/24 hours as an upper
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limit. Thus, the client will need to evaluate the following in light of a cost v. benefit analysis
(owner complaints and repairs/replacement), along with disclosure to owners.
Considering the E.I. test results, anticipated typical water vapor transmission rates, floor
coverings and improvements (to be chosen by the client) that can tolerate those rates
without distress, the following alternatives are provided:
Concrete slab underlayment should consist of a 10- to 15-mil vapor retarder, or
equivalent, with all laps sealed per the UBC/CBC (ICBO, 1997 and 2001; CBSC,
2007) and the manufacturer's recommendation. The vapor retarder should comply
with the ASTM E 1745 - Class A or Class B criteria, and be installed in accordance
with ACI 302.1R-04. The 10- to 15-mil vapor retarder (ASTM E 1745 - Class A or
Class B) shall be installed per the recommendations of the manufacturer, including
all penetrations (i.e., pipe, ducting, rebar, etc.).
Slab underlayment should consist of 2 inches of washed sand placed above a vapor
retarder consisting of 10- to 15-mil polyvinyl chloride, or equivalent, with all laps
sealed per UBC (ICBO, 1997). The vapor retarder shall be underlain by 4 inches of
pea gravel (1/2 to 3/4 subangular to angular clean crushed rock, 0 to 5 percent fines)
placed directly on the slab subgrade, and should be sealed to provide a continuous
water-resistant retarder under the entire slab, as discussed above. All slabs should
be additionally sealed with suitable slab sealant.
Concrete should have a maximum water/cement ratio of 0.50. This does not
supercede Table 19-A-4 of the UBC/CBC (ICBO, 1997 and 2001; CBSC, 2007) 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 above, 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.
Owner(s) should be specifically advised which areas are suitable for tile flooring,
wood flooring, or other types of water/vapor-sensitive flooring or equipment, and
which are not suitable. In all planned floor areas, flooring shall be installed per the
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.
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Regardless of the 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 of the flooring contractor should review the slab and
moisture retarder plans and provide comment prior to the construction of the residential
foundations or improvements. The vapor retarder contractor should have representatives
onsite during the initial installation.
SETBACKS
All footings or settlement-sensitive improvements should maintain a minimum horizontal
setback of H/3 (H = slope height) from the base of the footing to the descending slope
face. This setback should not be less than 7 feet, nor need not be greater than 40 feet.
This distance is measured from the improvement or footing face at the bearing elevation.
Footings adjacent to unlined drainage swales should be deepened to a minimum of
6 inches below the invert of the adjacent unlined swale. Footings for structures adjacent
to retaining walls should be deepened so as to extend below a 1:1 projection from the heel
of the wall. Alternatively, walls may be designed to accommodate structural loads from
buildings or appurtenances as described in the retaining wall section of this report.
PRELIMINARY SETTLEMENT ANALYSIS
GSI has previously estimated the potential magnitudes of total settlement, differential
settlement, and angular distortion for the site (GSI, 2007b). The analyses were based on
laboratory test results and subsurface data collected from borings completed in
preparation of that study. Site specific conditions affecting settlement potential include
depositional environment, grain size and lithology of sediments, cementing agents, stress
history, moisture history, material shape, density, void ratio, etc.
Ground settlement should be anticipated due to primary consolidation and secondary
compression of the left-in-place alluvium and compacted fills. The total amount of
settlement, and time over which it occurs, is dependent upon various factors, including
material type, depth of fill, depth of removals, initial and final moisture content, and in-place
density of subsurface materials. The structural engineer/foundation designer, and wall
designer, will need to consider the above, and other factors discussed below.
Post Grading Settlement of Compacted Fill
Compacted fills onsite, are not generally prone to excessive settlement. Based on our
previous analysis, total settlements, on the order of ½ inch, or less, may be anticipated
(GSI, 2007b).
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Post Grading Settlement of Alluvium
Where these materials are left in-place, settlement of the underlying saturated alluvium is
anticipated due to the weight of added planned fills. The magnitude of this settlement will
vary with the proposed fill heights (i.e., measured from existing grades), and the thickness,
texture, and compressibility of the underlying, left-in-place saturated alluvium. Due to the
predominantly fine grained texture of the alluvial soils onsite, settlement of the alluvial soil
will occur over time.
In areas underlain by alluvial soil, the material was removed to saturated conditions (i.e.,
±1 foot above regional ground water level) and recompacted. This resulted in leaving
alluvium in place. Previous calculated total settlements on the order of 3 to 8 inches
should be anticipated in these areas. Previous calculations were performed for total
settlements for planned fill thicknesses of 15, 20, and 30-feet within alluvial areas. The
calculated total settlements are estimated to be on the order of 4, 5.5, and 7.8 inches,
respectively. We estimate, about one-quarter of these computed settlements have
occurred during grading, with the remainder constituting the post grading component of
the total settlement. The anticipated post grade differential settlement is expected to be
about one-half of the remaining total settlement over a horizontal distance of 40 feet.
Waiting periods on the order of at least 18 months should be anticipated, to allow for an
adequate amount of settlement to occur prior to construction of settlement-sensitive
improvements. At this time, it is GSl's understanding that the area with left-in-place
saturated alluvium will remain a habitat corridor and no settlement-sensitive improvements
are planned. However, if future development plans include settlement-sensitive
improvements, monitoring may be warranted. Total settlement may be revised, dependant
on the actual field data from monitoring of monuments installed in areas were left-in-place
alluvium occurred, if warranted.
Monitoring
Areas where settlement-sensitive improvements are proposed on alluvial soil left-in-place
should be monitored biweekly and the settlement values revised based on actual field
data. Settlement monuments are recommended prior to construction. Monument
locations would be best provided during precise and/or development plan review.
Establishing a baseline now may ultimately reduce the estimated settlements, resulting in
less onerous design; however, since settlement-sensitive improvements are not proposed,
settlement monitoring does not appear warranted nor justified, at this time.
Dynamic Settlements
Ground accelerations generated from a seismic event (or by some man-made means) can
produce settlements in sands, both above and below the groundwater table. This
phenomena is commonly referred to as dynamic settlement and is most prominent in
relatively clean sands, but can also occur in other soil materials. The primary factor
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WALL DESIGN PARAMETERS CONSIDERING EXPANSIVE SOILS
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 are used to backfill any retaining walls. The type of backfill (i.e., select or native),
should be specified by the wall designer, and clearly shown on the plans. Building walls,
below grade, should be water-proofed. The foundation system for the proposed retaining
walls should be designed in accordance with the recommendations presented in this and
preceding sections of this report (settlement), as appropriate. Footings should be
embedded a minimum of 18 inches below adjacent grade (excluding landscape layer,
6 inches) and should be 24 inches in width. There should be no increase in bearing for
footing width. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.)
can be provided upon request, and would be based on site specific conditions.
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 65 pcf, plus 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 of the 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 City
and/or County 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 of the 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 conditions for superimposed loads can be provided upon
request.
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ACE SLOPE OF
SURFNED MATERIAL
HORIZONTAL-VERTICAL
EdUIVALENT
FLUID WEIGHT P;CF.
(SELECT .PREAPPRbVED
BAcKFILL**
EQUIVALENT
FLUID WEIGHT P.c.F.
(NATIVE PRE-APPROVED
BACKFILL***
Level* 40 45
2 to* l 60 65
* Level backfill behind a retaining wall is defined as compacted earth materials, properly drained, without
a slope fora distance of 2H behind the wall.
** E.I. <20, P.I. <15, SE >30, <10% passing No. 200 sieve.
Native backfill with EFW shown are for-very low to low expansive soils (El. 0-50, P.I. <15).
Retaining Wall Backfilland 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 necessaryfor retaining walls
that are 2 feet or greater in height. Details 1, 2, and 3, present the backdrainage options
discussed below. Backdrains should con'sis't of a 4-inch diameter perforated PVC or ABS
pipe enàasd in either Class 2 permeable filter material or 3/4-inch to 11/2-inch gravel
wrapped in approved filter fabric (Mirafi 1400requivalent). For low expansive backfill, the
'filter material should extend a minimum of 1 horizontal foot behind the base of the walls
.and upward at least 1 foot. For native backfill that has an E.I. up to 50,, continuous Class
2 permeabledràin materials should be used bhind the Nall' This material shoUld be
continuous (i.e., full height) behind the-wall, and it should beconstructedin accordance
with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited
access and confined aeas, (panel) drainage behindthe-wâll may be constructed in
accordance with Detail 2 (RëtainingWáll Backfill and Subdrain Detail Geotextile-Dràin).
Materialswith an 1E.1. potential of greater than 50 should not be used as backfill for
retaining walls For more onerous expansive situations, backfill and drainage behind the
retaining wall should conform with Detail 3 (Retainin'g Wall and Subdrain Detail Clean Sand
Backfill). •i . - ,
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 ue of weep holes,
only, in walls.higher than2 feet, is hot recommended. The surface of the babkfill should
be sealed by pavement or the top 18 inches compacted with native soil ([.1. ~50). Proper
surface drainage shoUld also be provided: For additional mitigation, consideration should
be given to applyinga water-proof membrane to the back of all retaining structures. The
ueof a waterstop should be considered forall concrete and masonry joints.
Wall/Retaining Wall Footing Tranitions
*
-
- Site walls' are 'anticipated to be founded on footings designed in accordance with the
recommendations in this report. Should wall footingstransition from cut to fill, ;the civil
designer may spcify ither:- •
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Structural footing or
settlement-sensitive improvement
Proposed grade I
sloped to drain
per precise civil
drawings
(5) Weep hole
Footing and wall
design by others
Provide surface drainage via an
/ engineered V-ditch (see civil plans
for details)
2:1 NO slope
1216ches ............... . . .....- .. . . .. \\
,- (2) Gravel
:Z:... ........... . .... . . ..
s— Native backf ill
1-1 (h:v) or flatter
backcut to be
properly benched
(1) Waterproofing
membrane
CMU or
reinforced-concrete
wall
J-,
±12 inches
(6) Footing
Waterproofing membrane.
Gravel: Clean, crushed, 3/4 to 1Y2 inch.
Filter fabric: Mirafi 140N or approved equivalent.
Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum
of 1 percent gradient sloped to suitable, approved outlet point (perforations down).
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.
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 A Detail 1
Structural footing or
(1) Waterproofing settlement-sensitive improvement -
membrane (optional)
. Provide surface drainage via engineered
V-ditch (see civil plan details)
CMU or 2.1 NO slope reinforced-concrete
wall
6 inches
I (2) Composite
(5) Weep hole—
,- Proposed grade Native backfill
/ sloped to drain
/ per precise civil ....:.. . .
..• ...
drawings (4) Pipe 11 NO or flatter
backcut to be
- .. I Footing and wall )
design by others (6) 1 cubic foot of
3/4-inch crushed rock
(7) Footing
(1) Waterproofing membrane (optional): Liquid boot or approved mastic equivalent.
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).
Filter fabric: Mirafi 140N or approved equivalent; place fabric flap behind core.
Cl
Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with
minimum of 1 percent gradient to proper outlet point (perforations down).
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.
Gravel: Clean, crushed, 3/4 to iY2 inch.
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.
I
G 'Ic. RETAINING WALL DETAIL - ALTERNATIVE B
I
Detail 2
±12 inches
(5) Weep hole -
H' Proposed grade
/ sloped to drain
J per precise civil
J drawings
Footing and wall
design by others
Structural footing or
settlement-sensitive improvement
/j21 NO slope
Provide surface drainage
)-'", (8) Native backfill
(6) Clean
sand backfill
1:1 NO or flatter
backcut to be ilter fabric properly benched
(2) Gravel
Heel
width (4) Pipe
(1) Waterproofing
membrane
CMU or
reinforced-concrete
wall
(7) Footing
Waterproofing membrane: Liquid boot or approved masticequivalent.
Gravel: Clean, crushed, 3/4 to 1)4 inch.
Filter fabric: Miraf I 140N or approved equivalent.
Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum
of 1 percent gradient to proper outlet point (perforations down).
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.
Clean sand backfill: Must have sand equivalent value (S.E.) of 35 or greater; can be
densitied by water jetting upon approval by geotechnical engineer.
Footing: If bench is created behind the footing greater than the footing width, use
level till or cut natural earth materials. An additional "heel" drain will likely be required by
geotechnical consultant.
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.
C. RETAINING WALL DETAIL - ALTERNATIVE C Detail 3
A minimum of a 2-foot overexcavation and recompaction of cut materials for a
distance of 2H, from the point of transition.
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 of the 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, regardless of whether or not transition
conditions exist. Expansion joints should be sealed with a flexible, non-shrink grout.
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
Soils at the site are likely to be expansive and therefore, become desiccated when allowed
to dry. 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 of these 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 of the 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 any owners and owners association and/or any 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 distresses, should be expected. To
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mitigate the tilting of top of slope walls/fences, we recommend that the walls/fences be
constructed on a combination of grade beam and caisson foundations. The grade beam
should be at a minimum 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 of the grade
beam. 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 the slump quantities. The concrete used should be appropriate to
mitigate sulfate corrosion, as warranted. The design of the grade beam 'and caissons
should be in accordance with the recommendations of the project structural engineer, and
include the utilization of the following geotechnical parameters:
Creep Zone: 5-foot vertical zone below the slope face and projected upward
parallel to the slope face.
Creep Load: 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 caisson, it should be taken as a
uniform 900 pounds per linear foot of caisson's depth, located
above the creep zone.
Point of Fixity: Located a distance of 1.5 times the caisson's diameter, below
the creep zone.
Passive Resistance: Passive earth pressure of 300 psf per foot of depth per foot of
caisson diameter, to a maximum value of 4,500 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 Capacity:
Shaft capacity: 350 psf applied below the point of fixity over the surface area
of the shaft.
Tip capacity: 4,500 psf.
EXPANSIVE SOILS, DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS
The soil materials on site are likely to 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
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for distress to improvements may be reduced, but not totally eliminated. To that end, it is
recommended that the developer should notify any owners, owners association, and/or
any interested/affected parties of this long-term potential for distress. To reduce the
likelihood of distress, the following recommendations are presented for all exterior flatwork:
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.
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.
Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and
approaches should additionally have a thickened edge (12 inches) adjacent to all
landscape areas, to help impede infiltration of landscape water under the slab.
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, 1/2 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.
No traffic should be allowed upon the newly poured concrete slabs until they have
been properly cured to within 75 percent of design strength. Concrete compression
strength should be a minimum of 2,500 psi.
Driveways, sidewalks, and patio slabs adjacent to the house should be separated
from the house 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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Planters and walls should not be tied to the house.
Overhang structures should be supported on the slabs, or structurally designed
with continuous footings tied in at least two directions.
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.
Utilities should be enclosed within a closed utilidor (vault) or designed with flexible
connections to accommodate differential settlement and expansive soil conditions.
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 owner, owners association, or any interested/affected
parties.
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. A/C waste water lines should
be drained to a suitable non-erosive outlet.
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
Pavement sections presented are based on the R-value data (to be verified by specific
R-value testing at completion of grading) from a representative sample taken from the
project area, the anticipated design classification, and the minimum requirements of the
City. For planning purposes, pavement sections consisting of asphaltic concrete over base
are provided. Anticipated asphaltic concrete (AC) pavement sections are presented on the
following table.
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S. I
S 4
ASPHALTIC CONCRETE PAVEMENT
TRAFAC
rnEed
SUBGRADE
NIPR..VALUE
THIcKNESS AGÔREGATEBASE
MIS
Local Street! 5.0
. 12 .. 4.0 4 6.0' Parking Lot
.
ColIect6r 6.0 12 ' 4.0 12.0.
"Dénotès standard Caltrans Class 2 aggregate base A 2.78, SE >22).
2 TI values have been assumed for planning purposes herein and should b confirmed by the design team during future plan development. .
The recommended pavement sections provided above are meant as minimums If thinner
or highly variable pavement sections are constructed, increased .maintenânce and repair
could be expected. If the ADT (average daily traffic) beyond that intended, asréflected by
the traffic index used for design, increased .rñaintenance and repair could be required for
the pavement section. .
..
: Subgrade preparation and aggregate base preparation' should be performed-in accordañbe with the recommèndatións presentèd belbw, and the minimum siibgrade
(upper .12 inches) and Class 2 aggregate base compaction should be 90 and 95 percent
of the maximum dry density' (ASTM D 1557), ràspectivély. If adverse conditions (i.e.,
saturated ground, etc.). are encountered. duhng preparation of subgrade, special
construction 'methods may need tobeemployed.
, .
.. . .
These recommendations should be considered preliminary. Further R-value testing and
pavement design analysis should be performed upon completion of. precise grading for,
the site.
S •
. S •. ,_. PAVEMENT GRADING RECOMMENDATIONS
Generl,
All section changes should be properly transitioned. If adverse conditions are encountered
during the.preparation of subgrade riiaterials, special construction methods may need to
be employed.
. . . S..,.
Subgrade'' S
Within street areas,all surficial deposits of loose boil material should be removed and
recompacted as recommended. After theloo'seoiIs 'are removed, the bottom is to be
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scarified to a depth of 12 inches, moisture conditioned as necessary and compacted to
95 percent of maximum laboratory density, as determined by ASTM test method D 1557.
Deleterious material, excessively wet or dry 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 ensure a
uniformly firm and unyielding surface. All grading and fill placement should be observed
by the project soil engineer and/or his representative.
Base
Compaction tests are required for the recommended base section. Minimum relative
compaction required will be 95 percent of the maximum laboratory density as determined
by ASTM test method D 1557. Base aggregate should be in accordance to the "Standard
Specifications for Public Works Construction" (green book) current edition.
Paving
Prime coat may be omitted if all of the following conditions are met:
The asphalt pavement layer is placed within two weeks of completion of base
and/or subbase course.
Traffic is not routed over completed base before paving.
Construction is completed during the dry season of May through October
The base is free of dirt and debris.
If construction is performed during the wet season of November through April, prime coat
may be omitted if no rain occurs between completion of base course and paving and the
time between completion of base and paving is reduced to three days, provided the base
is free of dirt and debris. Where prime coat has been omitted and rain occurs, traffic is
routed over base course, or paving is delayed, measures shall be taken to restore base
course, subbase course, and subgrade to conditions that will meet specifications as
directed by the soil engineer.
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. If
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planters or landscaping are adjacent to paved areas, measures should be taken to
minimize the potential for water to enter the pavement section.
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
(LIFE). Slope creep is caused by alternate wetting and drying of the fill soils which results
in slow downslope movement. This type of movement is expected to occur throughout the
life of the slope, and is anticipated to potentially affect improvements or structures (e.g.,
separations and/or cracking), placed near the top-of-slope, up to 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. LIFE 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 1997 UBC and/or adopted
California Building Code), 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 of these measures are recommended for design of
structures and improvements. The ramifications of the above conditions, and
recommendations for mitigation, should be provided to each owner and/or any owners
association.
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
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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 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 each owner or any interested/affected parties. Over-steepening of slopes
should be avoided during building construction activities and landscaping.
Drainage
Adequate lot 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 prevent ponding of water anywhere on a lot, and especially near structures and
tops of slopes. Lot 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 lots and common areas should be provided and maintained
at all times. Drainage should not flow uncontrolled down any descending slope. Water
should be directed away from foundations and not allowed to pond and/or seep into the
ground. In general, the area within 5 feet around a structure should slope away from the
structure. We recommend that unpaved lawn and landscape areas have a minimum
gradient of 1 percent sloping away from structures, and whenever possible, should be
above adjacent paved areas. Consideration should be given to avoiding construction of
planters adjacent to structures (buildings, pools, spas, etc.). 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.
Toe of Slope Drains/Toe Drains
Where significant slopes intersect pad areas, surface drainage down the slope allows for
some seepage into the subsurface materials, sometimes creating conditions causing or
contributing to perched and/or ponded water. Toe of slope/toe drains may be beneficial
in the mitigation of this condition due to surface drainage. The general criteria to be
utilized by the design engineer for evaluating the need for this type of drain is as follows:
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Is there a source of irrigation above or on the slope that could contribute to
saturation of soil at the base of the slope?
Are the slopes hard rock and/or impermeable, or relatively permeable, or; do the
slopes already have or are they proposed to have subdrains (i.e., stabilization fills,
etc.)?
Are there cut-fill transitions (i.e., fill over bedrock), within the slope?
Was the lot at the base of the slope overexcavated or is it proposed to be
overexcavated? Overexcavated lots located at the base of a slope could
accumulate subsurface water along the base of the fill cap.
Are the slopes north facing? North facing slopes tend to receive less sunlight (less
evaporation) relative to south facing slopes and are more exposed to the currently
prevailing seasonal storm tracks.
What is the slope height? It has been our experience that slopes with heights in
excess of approximately 10 feet tend to have more problems due to storm runoff
and irrigation than slopes of a lesser height.
Do the slopes "toe Out" into a residential lot or a lot where perched or ponded water
may adversely impact its proposed use?
Based on these general criteria, the construction of toe drains may be considered by the
design engineer along the toe of slopes, or at retaining walls in slopes, descending to the
rear of such lots. Following are Detail 4 (Schematic Toe Drain Detail) and Detail 5
(Subdrain Along Retaining Wall Detail). Other drains may be warranted due to unforeseen
conditions, owner irrigation, or other circumstances. Where drains are constructed during
grading, including subdrains, the locations/elevations of such drains should be surveyed,
and recorded on the final as-built grading p!ans by the design engineer. It is
recommended that the above be disclosed to all interested parties, including owners,
owners association, and any interested/affected parties.
Erosion Control
Cut and fill slopes will be subject to surficial erosion during and after grading. Onsite earth
materials have a moderate to high erosion potential. Consideration should be given to
providing hay bales and silt fences for the temporary control of surface water, from a
geotechnical viewpoint.
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Pad grade
/
Native
:. soil
cap
12-inch
Drain may be
constructed into, or
at, the toe-of-slope
I Drain pipe
Soil cap compacted to 90 percent relative compaction.
Permeable material may be gravel wrapped in filter fabric (Mirafi 140N or equivalent).
4-inch-diameter, perforated pipe (SDR-35 or equivalent) with perforations down.
Pipe to maintain a minimum 1 percent fall.
Concrete cut-off wall to be provided at transition to solid outlet pipe.
Solid outlet pipe to drain to approved area.
Cleanouts are recommended at each property line.
I
G
I
SCHEMATIC TOE DRAIN DETAIL • Detail 4
2:1 (H:V) slope (typical)
Backfill with compacted
native soils
Top of wall
Retaining wall
: 12 inches
:::• L
Finish grade Mirafi 140 filter
fabric or equivalent
3/4-inch crushed gravel
\
Wall footing
4-inch drain
ito 2 feet-i 12
inches
inches
L
NOTES:
Soil cap compacted to 90 percent relative compaction.
Permeable material may be gravel wrapped in filter fabric (Mirafi 140N or equivalent).
4-inch-diameter, perforated pipe (SDR-35 or equivalent) with perforations down.
Pipe to maintain a minimum 1 percent fall.
Concrete cut-off wall to be provided at transition to solid outlet pipe.
Solid outlet pipe to drain to approved area.
Cleanouts are recommended at each property line.
B. Effort to compact should be applied to drain rock.
I
SUBDRAIN ALONG RETAINING WALL DETAIL Detail 5
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
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 away from 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 barrier to 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
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 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 of the 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 due to 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.
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Site Improvements
If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the
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 the owners, any owners
association, and/or other interested parties. This office should be notified in advance of
any fill placement, grading of the site, or trench backfilling after rough grading has been
completed. This includes any grading, utility trench and retaining wall backlills, flatwork,
etc.
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 of this 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 of the 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. -
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Trenching/Temporary Construction Backcuts
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
[except as specifically superceded within the text of this report]), should be anticipated.
All 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 owners, etc., that may perform such
work.
Utility Trench Backfill
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 of the 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.
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.
All trench excavations should conform to Cal-OSHA, state, and local safety codes.
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 of the
structural engineer.
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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, toe drains, 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.).
During retaining wall subdrain installation, prior to 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 owner improvements, such as flatwork, spas, pools, walls,
etc., are constructed, prior to construction. GSI should review and approve such
plans prior to 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.
GSI should review project sales documents to owners/owners associations for
geotechnical aspects, including irrigation practices, the conditions outlined above,
etc., prior to any sales. At that stage, GSI will provide owners maintenance
guidelines which should be incorporated into such documents.
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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 for the 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.
If the structural engineer/designer has any questions or requires further assistance, they
should not hesitate to call or otherwise transmit their requests to GSl. 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 recom.mendations and/or further geotechnical studies may be
warranted.
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LIMITATIONS
The materials encountered on the project site and utilized for our analysis are believed
representative of the 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 properly implemented. Use of this report constitutes an
agreement and consent by the user to all the limitations outlihed 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. All samples will be disposed of after 30 days, unless
specifically requested by the Client, in writing.
Robertson Family Trust W.O. 5247-132-SC
PA-1 1, Robertson Ranch West July 16, 2008
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GeoSoils, Inc.
The oppoñunity to be of service is sincerely appreciated. If you should have any
questions, please do not hesitate to contact the project manager, Bryan E. Voss, at our
office.
Respectfully submitted,
GeoSoils, Inc.
oss
Certified '0-
ohn P. Franklin Engineering Be hah I
Engineering Geol 4 Go ec. ical Engneer,
BEV/JPF/BBS/jk
Attachments: Table 1 - Field Density Test Results
Appendix - References
Plates 1, 2, 3, and 4 - Field Density Test Location Maps
Distribution: (4) Addressee
(1) O'Day Consultants, Attention: Mr. Keith Hansen
Robertson Family Trust W.O. 52477132-SC
PA-1 1, Robertson Ranch West July 16, 2008
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GeoSoils, Inc.
Table 1
FIELD DENSITY TEST RESULTS
:TJ.EST :DATE TESTLOCATION. ::ELEV:
DEPTH (it)
MOISTURE
CONTENT
(%)
DRW
DENSITY
(pci)
REL1
:op
(%)
H.TET:
METHOD.
'SOJL
TYPE
1 4/7/08 SW PA-li 38.0 15.8 107.7 91.3 ND A
2 4/7/08 SW PA-li 38.0 14.9 107.1 90.8 ND A
3 4/7/08 SW PA-1 1 40.0 16.0 106.8 90.5 ND A
4 4/8/08 SW PA-li 42.0 13.8 106.9 90.6 ND A
5 4/8/08 SW PA-li 40.0 14.2 106.6 90.3 Sc A
6 4/8/08 SW PA-il 42.0 15.5 108.0 91.5 ND A
7 4/8/08 SW PA-il 44.0 11.8 115.5 90.2 ND B
8 4/8/08 SW PA-li 44.0 12.5 115.2 90.0 ND B
9 4/8/08 SW PA-il 46.0 14.5 107.3 90.9 ND A
10 4/8/08 SW PA-il 45.0 12.8 114.2 92.1 Sc D
11 4/9/08 SW PA-li 46.0 12.8 110.4 90.5 ND F
12 4/9/08 SW PA-il 46.0 14.2 107.0 90.7 ND A
13 4/9/08 SW PA-il 46.0 14.0 109.8 90.0 ND F
14 4/9/08 SW PA-il 48.0 12.8 110.8 90.8 ND F
15 4/9/08 SW PA-li 48.0 13.2 109.9 90.1 Sc F
16 4/9/08 SW PA-1 1 48.0 14.4 106.6 90.3 ND A
17 4/9/08 SW PA-1 1 49.0 14.2 107.4 91.0 ND A
18 4/10/08 SW PA-li 48.0 13.5 110.2 90.3 SC F
19* 4/10/08 SW PA-li 48.0 12.6 105.7 86.6 ND F
19A 4/10/08 SW PA-li 48.0 13.5 110.5 90.6 ND F
20 4/10/08 SW PA-li 48.0 13.0 109.8 90.0 ND F
21 * 4/10/08 SW PA-1 1 51.0 11.5 108.9 89.3 ND F
21 4/10/08 SW PA-il 48.0 12.9 109.8 90.0 SC F
22 4/10/08 SW PA-il 51.0 12.7 110.5 90.6 ND F
23 4/10/08 SW PA-il 43.0 12.1 113.2 91.3 SC D
24 4/10/08 SW PA-il 43.0 14.2 107.5 91.1 ND A
25 4/10/08 SW PA-il 53.0 12.7 110.5 90.6 ND F
26 4/10/08 SW PA-il 53.0 12.5 109.9 90.1 ND F
27 4/10/08 SW PA-li 55.0 12.6 111.2 91.1 ND F
28* 4/11/08 Swale @ Subdrain 1 52.0 10.1 110.0 90.2 ND F
28A 4/11/08 Swale @ Subdrain 1 52.0 1 12.5 113.6 93.1 ND F
29 4/11/08 Fill Slope East of Headwall 52.0 13.6 112.0 91.8 ND F
30 4/11/08 NW PA-il 46.0 15.1 110.3 93.5 ND A
31 4/11/08 NW PA-il 47.0 16.1 108.5 91.9 SC A
32 4/11/08 NWPA-il 48.0 15.9 109.7 93.0 SC A
33 4/14/08 SW PA-li 54.0 13.6 107.0 90.7 SC A
34 4/14/08 SW PA-il 52.0 14.0 106.7 90.4 ND A
35 4/14/08 SW PA-il 50.0 13.7 106.9 90.6 ND A
36 4/14/08 SW PA-1 1 36.0 12.8 110.5 90.6 ND F
37 4/14/08 NW PA-il 38.0 12.9 110.0 90.2 ND F
38 4/14/08 NW PA-il 37.0 13.0 111.4 91.3 SC F
39 4/14/08 NW PA-li 40.0 12.8 109.9 90.1 ND F
40 4/14/08 NW PA-il 43.0 10.2 1 116.5 1 91.0 1 ND B
Robertson Family Trust W.O. 5247-B2-SC
PA-1 1, Robertson Ranch West July 2008
File: C:\excel\tables\5200/5247b2rom Page 1
GeoSoils, Inc.
TRhlp 1
FIELD DENSITY TEST RESULTS
TEST TLOCATION ELEV
•.. ::OR
DEPTH
MOISTURE......DRY:`
CONTENT: DENSITY
REL:
COMP
(%)
.:
METHOD:
S011
:TYPIE
41 4/15/08 SW PA-il 44.0 12.6 113.8 93.3 ND F
42 4/15/08 sw PA-il 46.0 13.1 111.5 91.4 ND F
43 4/15/08 sw PA-il 46.0 12.8 111.4 91.3 ND F
44 4/15/08 sw PA-il 46.0 12.8 110.8 90.8 Sc F
45 4/15/08 sw PA-il 48.0 14.0 107.8 91.4 ND A
46 4/15/08 sw PA-il 48.0 13.7 106.9 90.6 ND A 47* 4/15/08 SW PA-1 1 50.0 10.0 108.8 87.7 ND D
47A 4/15/08 SW PA-li 50.0 12.9 112.2 90.5 ND D
48* 4/15/08 SW PA-li 50.0 9.4 110.0 85.9 ND B
48A 4/15/08 SW PA-li 50.0 13.8 115.5 90.2 sc B
49 4/16/08 NW PA-1 1 44.0 13.5 111.5 91.4 ND F
50 4/16/08 NW PA-il 46.0 14.0 110.8 90.8 ND F
51 4/16/08 NW PA-1 1 46.0 12.9 111.0 91.0 SC F
52 4/16/08 NW PA-il 46.0 13.2 110.4 90.5 ND F
53 4/16/08 NW PA-il 48.0 12.5 109.8 90.0 ND F 54* 4/16/08 NW PA-il 48.0 8.8 104.8 85.9 ND F
54A* 4/17/08 NW PA-li 48.0 10.8 108.5 88.9 sC F
54B 4/17/08 NW PA-li 48.0 14.0 110.8 90.8 ND F 55* 4/16/08 NW PA-li 50.0 7.0 105.2 86.2 ND F
55A* 4/17/08 NW PA-il 50.0 9.9 109.1 89.4 ND F
55B 4/17/08 NW PA-1 1 50.0 13.7 110.7 90.7 ND F
56 4/17/08 NW PA-1 1 53.0 11.8 112.8 91.0 ND D
57 4/17/08 NW PA-il 55.0 10.5 115.2 90.0 SC B
58 4/17/08 NWPA-ll 58.0 10.0 115.8 90.5 ND B
50 4/17/08 NW PA-ll 61.0 12.9 112.0 90.3 ND D
60 4/17/08 NW PA-1 1 65.0 11.8 112.4 90.6 ND D
61 4/17/08 NW PA-il 65.0 14.2 107.5 91.1 ND A
62 4/17/08 NW PA-li .. 67.0 13.8 106.9 90.6 SC A
63 4/17/08 . NW PA-il 69.5 14.0 107.0 90.7 ND A
64 4/18/08 NW PA-li. 50.0 13.8 106.6 90.3 ND A
65 4/18/08 NW PA-li 52.0 13.9 106.8 90.5 ND A
66 4/18/08 NW PA-1 1 54.0 14.0 110.4 90.5 ND F
67 4/18/08 NW PA-il 56.0 13.7 109.9 90.1 ND F
68 4/18/08 NW PA-1 1 49.0 13.8 1077 91.3 SC A
69 4/21/08 SW PA-il 54.0 12.8 111.8 90.2 SC D
70 4/21/08 SW PA-il 54.0 13.1 111.9 90.2 ND D
71 4/21/08 SW PA-li 56.0 12.5 1124 90.6 ND D
72 4/21/08 SW PA-li 56.0 14.0 111.9 90.2 ND D
73 4/21/08 SW PA-il 58.0 13.8 112.5 90.7 ND D
74 4/22/08 SW PA-il 56.0 14.2 106.9 90.6 ND A
75 4/22/08 SW PA-il 56.0 13.8 108.1 91.6 ND A
76 4/22/08 SW PA-il 58.0 12.9 111.9 91.7 ND F
77 4/22/08 SW PA-il 1 71.0 14.0 107.1 90.8 1 ND A
Robertson Family Trust W.O. 5247-132-SC
PA-1 1, Robertson Ranch West July 2008
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GeoSoils, Inc.
Table 1
FIELD DENSITY TEST RESULTS
:TEST DATE: :.ELEW.:::
DEPTH (tt)
MOISTURE
CONTENT .
(%)
:DENSjT.
:REL
cMP O1
E5:
METHO.D
LOlL:
TYPE
78 4/22/08 SW PA-il 71.0 13.8 106.8 90.5 Sc A
79 4/23/08 SW PA-1 1 58.0 15.9 106.5 90.3 SC A
80 4/23/08 SW PA-1 1 58.0 16.0 107.2 90.8 ND A
81 4/23/08 SW PA-li 60.0 17.5 106.4 90.2 ND A
82 4/23/08 SW PA-il 60.0 15.5 106.6 90.3 ND A
83 4/23/08 SW PA-1 1 60.0 16.2 107.0 90.7 ND A
84 4/24/08 SWPA-il 62.0 15.8 106.5 90.3 ND A
85 4/24/08 SW PA-1 1 62.0 16.0 111 .7 90.1 SC D
86 4/24/08 SW PA-il 64.0 17.5 111.9 90.2 ND D
87 4/24/08 SW PA-1 1 64.0 15.5 110.8 90.8 ND F
88 4/24/08 SW PA-il 66.0 16.2 107.0 90.7 ND A
89 4/24/08 SW PA-li 66.0 15.2 106.4 90.2 SC A
90 4/24/08 SW PA-il 66.0 14.9 107.0 90.7 ND A
91 4/25/08 PA-li (El Camino Real) 36.0 15.8 106.9 90.6 ND A
92 4/25/08 PA-il (El Camino Real) 36.0 16.0 107.5 91.1 ND A
93 4/25/08 PA-il (El Camino Real) 37.5 17.5 106.5 90.3 ND A
94 4/25/08 PA-il (El Camino Real) 37.5 15.5 106.6 90.3 ND A
95 4/28/08 NW PA-1 1 70.0 24.7 93.5 911 SC E
96 4/28/08 NW PA-1 1 70.0 23.8 91.8 90.0 ND E
97 4/28/08 NW PA-li 70.0 15.8 107.7 91.3 ND A
98 4/28/08 NW PA-1 i 72.0 21.7 92.0 90.2 ND E
99 4/28/08 NW PA-il 72.0 13.8 112.1 91.9 ND F
100 4/28/08 NW PA-1 1 72.0 14.0 111 .7 91.6 Sc F
101 4/28/08 NW PA-li 74.0 23.7 92.0 90.2 ND E
102 4/28/08 PA-il (El Camino Real) 40.0 14.5 114.8 92.6 ND D
103 4/28/08 PA-il (El Camino Real) 40.0 13.7 113.2 91.3 ND D
104 4/29/08 NW PA-1 1 1 74.0 24.7 106.6 90.3 ND A
105 4/29/08 NW PA-il 74.0 23.8 106.5 90.3 ND A
106 4/29/08 NW PA-li 76.0 15.8 106.8 90.5 ND A
107 4/29/08 NW PA-il 76.0 14.7 111.4 91.3 ND F
108 4/29/08 NW PA-li 73.0 21.8 91.9 90.1 SC E
109 4/29/08 NW PA-1 1 78.0 24.0 91.8 90.0 ND E
110 4/29/08 NW PA-li 78.0 13.7 106.9 90.6 ND A
ill 4/29/08 NW PA-1 i 78.0 14.2 107.7 91.3 ND A
112 4/29/08 NW PA-li 80.0 13.8 107.5 91.1 ND A 113* 4/29/08 NW PA-il 80.0 14.9 104.8 88.8 SC A
113A 4/29/08 NW PA-il 80.0 14.0 107.5 91.1 ND A 4* 4/29/08 NW PA-1 1 80.0 15.2 103.0 87.3 ND A
114A 4/29/08 NW PA-li 80.0 13.9 106.9 90.6 ND A
115 4/30/08 NWPA-ll 80.0 22.3 91.9 90.1 ND E
116 4/30/08 NW PA-1 1 82.0 21.8 92.2 90.4 ND E
117 4/30/08 NW PA-1 1 82.0 24.2 91.8 90.0 ND E
118 1 4/30/08 1 NW PA-1 1 82.0 23.3 92.7 1 90.9 ND E
Robertson Family Trust W.O. 5247-132-SC
PA-1 1, Robertson Ranch West July 2008
File: C:\excel\tab!es\5200/5247b2.rom Page 3
GeoSoils, Inc.
Table 1
FIELD DENSITY TEST RESULTS
:.FEs.F: ::.:: OCA'flO1li:;:E:
:..
.LEV
DEPTH (ft)
IVIOIST:URE
C.CI.PJ1Eli
(%)
DE.t'Slr(
(pcf)
.cc.FilPI
(%)
11EFI1cID.
:5C1L
1J. ?P.E
119 4/30/08 NW PA-li 84.0 22.4 93.0 91.2 Sc E
120 4/30/08 NW PA-il 84.0 24.3 92.1 90.3 ND E
121 4/30/08 NW PA-il 84.0 12.6 111.8 90.2 ND 0
122 4/30/08 NW PA-1 1 86.0 12.2 111.9 90.2 ND D
123 4/30/08 NW PA-il 86.0 14.2 107.7 91.3 ND A
124 4/30/08 NW PA-1 1 86.0 12.9 112.5 90.7 Sc D
125 5/1/08 NW PA-li 88.0 14.2 106.6 90.3 ND A
126 5/1/08 NW PA-li 88.0 16.5 106.8 90.5 ND A
127 5/1/08 NWPA-li 88.0 13.8 107.4 91.0 ND A
128 5/1/08 NW PA-li 90.0 15.5 106.8 90.5 ND A
129 5/1/08 NW PA-il 90.0 13.2 110.2 90.3 ND F
130 5/1/08 NW PA-il 90.0 12.8 110.1 90.2 ND F
131 5/1/08 NW PA-li 92.0 14.7 108.4 91.9 ND A
132 5/1/08 PA-li (El Camino Real) 31.0 14.2 111.8 902 ND D
133 5/1/08 PA-li (El Camino Real) 31.0 13.8 111.6 90.0 ND D
134 5/2/08 NW PA-li 92.0 16.0 106.6 90.3 SC A
135 5/2/08 NW PA-li 92.0 15.5 106.8 90.5 ND A
136 5/2/08 NW PA-li 94.0 14.2 107.4 91.0 ND A
137 5/2/08 NW PA-il 94.0 14.6 106.8 90.5 ND A
138 5/2/08 NW PA-li 94.0 15.1 110.2 93.4 ND A
139 5/2/08 PA-li (El Camino Real) 34.0 14.2 110.1 93.3 SC A
140 5/2/08 PA-il (El Camino Real) 34.5 13.8 108.4 91.9 ND A
141 5/2/08 PA-il (El Camino Real) 37.0 13.1 111.8 91.6 ND F
142 5/2/08 PA-li (El Camino Real) 39.0 12.7 111.6 91.5 ND F
143 5/5/08 NW PA-li 96.0 13.0 110.2 90.3 ND F
144 5/5/08 NW PA-li 96.0 12.8 109.9 90.1 ND F
145 5/5/08 NW PA-li 96.0 13.7. 106.5 90.3 ND A
146 5/5/08 NW PA-il 98.0 14.1 106.7 90.4 ND A
147 5/5/08 NW PA-1 1 98.0 13.8 106.6 90.3 ND A
148 5/5/08 PA-li (El Camino Real) 41.0 14.2 107.1 90.8 ND A
149 5/5/08 PA-il (El Camino Real) 42.0 14.0 106.3 90.1 ND A
150 5/5/08 PA-il (El Camino Real) 44.0 13.7 106.5 90.3 ND A
151 5/5/08 PA-li (El Camino Real) 46.0 14.2 106.2 90.0 ND A
152 5/6/08 SW PA-il 55.0 14.7 106.9 90.6 ND A
153 5/6/08 SW PA-li 56.5 15.1 106.6 90.3 ND A
154 5/6/08 SW PA-il 58.0 12.9 109.8 90.0 ND F
155 5/6/08 SW PA-il 60.0 14.1 106.4 90.2 ND A
156 5/6/08 SW PA-li 62.0 13.8 107.4 91.0 sc A
157 5/7/08 SW PA-li 60.0 13.8 106.2 90.0 Sc A
158 5/7/08 SW PA-il 62.0 14.4 107.0 90.7 ND A
159 5/7/08 SW PA-il 64.0 14.2 107.5 91.1 ND A
160 5/7/08 SW PA-li 64.0 14.0 106.4 90.2 ND A
161 5/7/08 SW PA-1 1 66.0 13.8 106.5 90.3 ND A
Robertson Family Trust W.O. 5247-132-Sc
PA-1 1, Robertson Ranch West July 2008
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GeoSoils, Inc.
Table 1
FIELD DENSITY TEST RESULTS
TES1r
DEPTH (ft) (%)
D:ENS.I1.!.
(pcf)
coiitp
TE
ffl1FlcI:D: F(PEI
162 5/8/08 SW PA-1 1 62.0 13.8 106.2 90.0 ND A
163 5/8/08 NW PA-li 64.0 14.4 107.0 90.7 ND A
164 5/8/08 NW PA-li 66.0 14.2 107.5 91.1 ND A
165 5/8/08 SW PA-1 1 66.0 14.0 106.4 90.2 ND A
166* 5/8/08 SW PA-li 68.5 10.2 105.8 89.7 ND A
166A 5/8/08 SW PA-1 1 68.5 13.9 106.9 90.6 SC A
167 5/13/08 South Arizona Crossing 32.0 14.9 106.4 90.2 ND A
168 5/13/08 South Arizona Crossing 33.0 15.7 106.2 90.0 ND A
169 .5/15/08 SW PA-li 57.0 12.8 111.8 90.2 ND D
170 5/15/08 SW PA-il . 57.0 11.8 112.1 90.4 ND D
171 5/15/08 SW PA-1 1 59.0 12.2 111.6 90.0 ND D
172 5/15/08 SW PA-1 1 59.5 14.0 107.2 90.8 ND A
173 5/15/08 SW PA-1 1 61.0 13.0 110.5 90.6 SC F
174 5/15/08 SW PA-li 61.5 12.7 109.9 90.1 ND F
175 5/16/08 SW PA-li 63.5 14.9 106.8 90.5 ND A
176 5/16/08 SW PA-li 65.0 14.2 106.5 90.3 ND A
177 5/16/08 SW PA-li 66.0 13.7 107.1 90.8 ND A
178 5/16/08 SW PA-1 1 68.0 13.9 106.5 90.3 SC A
179 5/16/08 SW PA-1 i 68.0 14.6 106.9 90.6 ND A
180 5/16/08 SW PA-1 1 70.0 13.9 107.7 91.3 ND A
181 5/19/08 SW PA-1 1 72.0 14.8 107.4 91.0 SC A
182 5/19/08 SW PA-1 1 72.0 14.2 106.8 90.5 ND A
183 5/19/08 SW PA-il 75.0 13.9 107.0 90.7 ND A
184 5/19/08 SW PA-li 77.0 12.0 113.0 90.4 ND C
185 5/19/08 SW PA-il 79.0 12.5 112.8 90.2 ND C
186 5/19/08 SW PA-li 80.0 11.5 116.1 90.7 SC B
187 5/19/08 SW PA-1 1 80.0 11.7 113.3 90.6 ND C
188 5/19/08 SW PA-1 1 82.0 14.5 106.6 90.3 ND A
189 5/19/08 SW PA-il . 82.0 13.9 107.2 90.8 ND A
190 5/19/08 SW PA-li 84.0 14.0 106.5 90.3 ND A
191 5/19/08 SW PA-1 1 84.0 14.2 106.8 90.5 Sc A
192 5/19/08 SW PA-il 86.0 14.5 106.9 90.6 ND A
193 5/19/08 SW PA-1 1 86.0 105 115.7 90.4 ND B
194 5/19/08 SW PA-1 1 88.0 115 114.6 92.4 ND D
195 5/19/08 SW PA-il 88.0 11.7 115.2 92.9 ND D
196 5/19/08 SW PA-1 1 90.0 11.2 116.2 90.8 SC B
197 5/19/08 SW PA-il 90.0 14.2 106.5 90.3 ND A
198 5/19/08 SW PA-li 92.0 15.0 106.9 90.6 ND A
199 5/19/08 NW PA-li 94.0 13.8 107.1 90.8 ND A
200 5/19/08 NW PA-1 1 96.0 13.5 106.6 90.3 ND A
201 5/19/08 NWPA-ll 96.5 14.2 107.5 91.1 SC A
202 5/19/08 NW PA-li 98.0 14.6 107.1 90.8 1 ND A
S-203 5/20/08 SW Basin PA-li 1 70.0 13.5 107.0 90.7 1 ND A
Robertson Family Trust W.O. 5247-132-SC
PA-1 1, Robertson Ranch West July 2008
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GeoSoils, Inc.
Table 1
FIELD DENSITY TEST RESULTS
TEST DATE TEST LOCATION
.:::
ELEV
DEPTH (ft)
.NTENT
MOISTURE
(%)
DRY
(pcf)
REL
ccIQ1Ip:
(%)
TEST SOiL
lr.p:E
S-204 5/20/08 SW Basin PA-li 75.0 13.7 106.7 90.4 ND A
S-205 5/20/08 SW Basin PA-li 75.0 13.8 106.9 90.6 ND A
S-206 5/20/08 SW Basin PA-li 80.0 13.5 106.3 90.1 ND A
S-207 5/20/08 sw Basin PA-li 80.0 14.2 106.8 90.5 ND A
S-208 5/20/08 SW Basin PA-li 85.0 13.8 107.2 90.8 ND A
S-209 5/20/08 SW Basin PA-li 85.0 13.5 106.8 90.5 ND A
S-210 5/20/08 SW Basin PA-il 90.0 13.5 106.5 90.3 ND A
S-211 5/21/08 sw Basin PA-il 94.0 1 .14.2 107.0 90.7 ND A
S-212 5/21/08 SW Basin PA-li 94.0 15.5 106.7 90.4 ND A
S-213 5/21/08 SW Basin PA-li 94.0 11.9 112.9 90.3 ND C
S-214 5/21/08 SW Basin PA-li 98.0 12.0 113.3 90.6 ND C
S-215 5/21/08 sw Basin PA-li 98.0 13.8 106.8 90.5 ND A
S-216 5/21/08 sw Basin PA-li 98.0 13.7 107.2 90.8 ND A
S-217 5/28/08 El Camino Real (East of Culvert) 35.0 13.5 106.5 90.3 ND A
S-218 5/28/08 El Camino Real (East of Culvert) 37.0 14.1 106.8 90.5 ND A
S-219 5/28/08 El Camino Real (East of Culvert) 39.0 13.7 106.2 90.0 ND A
S-220 5/28/08 El Camino Real (East of Culvert) 41.0 13.6 107.7 91.3 ND A
S-221 5/28/08 El Camino Real (West of Culvert) 43.0 14.0 -106.8 90.5 ND A
S-222 5/28/08 El Camino Real (West of Culvert) 44.0 13.5 107.1 90.8 ND A
S-223 5/28/08 El Camino Real (West of Culvert) 47.0 11.5 112.5 90.7 ND D
S-224 5/28/08 El Camino Real (West of Culvert) 50.0 12.2 112.9 91.0 ND D
S-225 5/28/08 El Camino Real (West of Culvert) 53.0 11.9 112.8 90.2 ND C
.S-226 5/28/08 El Camino Real (West of Culvert) 56.0 13.5 106.5 90.3 ND A
S-227 5/28/08 El Camino Real (West of Culvert) 59.0 .13.6 . 106.6 90.3 ND A
S-228 5/29/08 NW PA-li 45.0 13.9 107.2 90.8 ND A
S-229 5/29/08 NW PA-1 1, 45.0 13.5 106.5 90.3 ND A
S-230 5/29/08 NW PA-li 50.0 13.9 107.0 90.7 ND A
S-231 5/29/08 NW PA-il 50.0 14.2 106.9 90.6 ND A
S-232 5/29/08 . NW PA-1 1 50.0 13.8 106.5 90.3 ND A
S-233 5/29/08 . NW PA-1 1 55.0 13.8 106.2 90.0 ND A
S-234 5/29/08 NW PA-il 55.0 11.5 113.1 90.5 ND C
S-235 5/29/08 NW PA-li 55.0 11.9 112.8 90.2 ND C
S-236 5/29/08 NWPA-ii 60.0 12.5 113.3 90.6 ND C
S-237 5/29/08 NW PA-il 60.0 12.2 113.9 91.1 ND C
S-238 5/29/08 NW PA-li 60.0 12.1 113.0 90.4 ND C
S-239 5/29/08 NW PA-li 65.0 13.5 106.8 90.5 ND A
S-240 5/29/08 NW PA-il 65.0 11.6 113.4 90.7 ND C
S-241 5/29/08 NW PA-li 65.0 11.8 112.8 90.2 ND C
S-242 5/29/08 NW PA-li 70.0 13.7 107.2 90.8 ND A
S-243 5/29/08 NW PA-li 70.0 14.5 106.5 90.3 ND A
S-244 5/29/08 NW PA-li 70.0 13.9 106.6 90.3 ND A
S-245 5/29/08 NW PA-li 70.0 . 12.2 112.6 1 90.8 ND D
S-246 5/29/08 NW PA-1 1 75.0 11.6 112.2 1 90.5 ND D
Robertson Family Trust W.O. 5247-B2-SC
PA-1 1, Robertson Ranch West July 2008
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Table 1
FIELD DENSITY TEST RESULTS
TEST LOATlON • ELEV
I:.ORr.
MOISTURE
.CONTENT.
1 :DRY.' REL.
COMPI
(%)
METHOD
:SOI[:
TTYPE.
S-247 5/29/08 NW PA-1 1 75.0 11.8 112.8 90.2 ND C
S-248 5/29/08 NW PA-1 1 75.0 11.5 112.7 90.2 ND C
S-249 5/29/08 NW PA-il 75.0 137 106.6 90.3 ND A
S-250 6/3/08 NW PA-1 1 80.0 11.6 112.8 90.2 ND C
S-251 6/3/08 NW PA-li 80.0 12.3 113.1 90.5 ND C
S-252 6/3/08 NW PA-1 1 85.0 11.5 112.8 90.2 ND C
S-253 6/3/08 NW PA-li 85.0 11.7 112.6 90.1 ND C
S-254 6/3/08 NW PA-1 1 90.0 12.0 112.8 90.2 ND C
S-255 6/3/08 NW PA-il 90.0 13.8 106.8 90.5 ND A
S-256 6/3/08 NW PA-1 1 95.0 11.7 115.2 92.9 ND D
S-257 6/3/08 NW PA-1 1 95.0 11.4 113.5 90.8 ND C
S-258 6/3/08 NW PA-li 50.0 113.9 106.9 90.6 ND A
S-259 6/3/08 NW PA-li 50.0 13.5 107.5 91.1 ND A
S-260 6/3/08 NW PA-li 55.0 3.8 - 106.6 90.3 ND A
S-261 6/3/08 NW PA-il 55.0 12.9 112.8 90.2 ND C
S-262 6/3/08 NW PA-li 60.0 11.5 113.0 91.1 ND D
S-263 6/3/08 NW PA-1 1 60.0 13.6 106.5 90.3 ND A
S-264 6/3/08 NW PA-il 65.0 13.8 1071 90.8 ND A
S-265 6/3/08 NW PA-il 65.0 13.5 106.9 90.6 ND A
S-266 6/3/08 NW PA-li 70.0 10.6 115.3 90.1 ND B
S-267 6/3/08 NW PA-il 70.0 11.0 115.8 905 ND B
S-268 6/3/08 NW PA-il 75.0 11.9 112.8 90.2 ND C
S-269 6/3/08 NW PA-il 80.0 13.5 106.6 90.3 ND A
S-270 6/3/08 NW PA-il 85.0 14.1 107.0 90.7 ND A
S-271 6/3/08 NW PA-li 90.0 13.8 106.8 90.5 ND A S272* 6/5/08 N. SDG&E Rd. 96.0 7.0 104.5 88.6 ND A
S-272A 6/9/08 N. SDG&E Rd. 96.0 13.7 107.6 91.2 ND A
S273* 6/5/08 N. SDG&E Rd. 97.0 7.4 103.7 87.9 ND A
S-273A 6/9/08 N. SDG&E Rd. 97.0 13.6 106.8 90.5 ND A
274 6/9/08 N. PA-li FG 14.1 107.0 90.7 ND A
275 6/9/08 NW PA-ll FG 13.8 106.4 90.2 ND A
S-276 6/9/08 N. SDG&E Rd. 97.0 12.8 110.7 90.7 Sc F
S-277 6/9/08 N. SDG&E Rd. 98.0 12.9 112.1 91.9 ND F
278 6/9/08 N. PA-li FG 13.7 106.9 90.6 ND A
279 1 6/9/08 W. PA-il FG 1 13.5 106.6 90.3 ND A
LEGEND:
* = Failed Test
A = Retest
FG = Finish Grade
ND = Nuclear Densometer
S = Slope
SC = Sand Cone
Robertson Family Trust W.O. 5247-132-SC
PA-1 1, Robertson Ranch West July 2008
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APPENDIX
REFERENCES
California Building Standards Commission, 2007, California building code.
Dietrich, W.E., and Dorn, R., 1984, Significance of thick deposits of colluvium on hilislopes:
A case study in the coastal mountains of northern California, Journal of Geology,
v. 92, p. 133-146.
GeoSoils, Inc., 2007a, Geotechnical review of rough grading plans, Robertson Ranch
Habitat Corridor, Carlsbad, San Diego County, California 92010, W.O. 5247-A3-SC,
dated October 17.
2007b, Preliminary geotechnical evaluation, Planning Area 11, Robertson Ranch
Habitat Corridor and widening of El Camino Real at Cannon Road, Robertson
Ranch West, Carlsbad, San Diego County, California 92010, City of Carlsbad
Planning Department Application No. SUP 06-12/HDP 06-04, W.O. 5247-Al-SC,
dated January 31.
2004, Updated geotechnical evaluation of the Robertson Ranch property, Carlsbad,
San Diego County, California, W.O. 3098-A2-SC, dated September 20.
2002, Geotechnical evaluation of the Robertson Ranch properly, City of Carlsbad,
San Diego County, California, W.O. 3098-Al-SC, dated January 29.
International Code Council, Inc., 2006, International building code and international
residential code for one- and two-family dwellings.
International Conference of Building Officials, 2001, California building code, California
code of regulations title 24, part 2, volume 1 and 2.
1997, Uniform building code: Whittier, California, International conference of
building officials, Volumes 1, 2, and 3: especially Chapter 16, Structural forces
(earthquake provisions); Chapter 18, Foundations and retaining walls; and
Chapter A-33, Excavation and grading.
Kanare, Howard, M., 2005, Concrete Floors and Moisture, Engineering Bulletin 119,
Portland Cement Association.
O'Day Consultants, 2006, Grading plans for Robertson Ranch Habitat Corridor,
Sheet 1 through 6, Job no. 01-1014, dated December 14.
GeoSoils, Inc.
Shiemon, R.J., Wright, RH., and Montgomery, DR., 1987, Anatomy of a debris flow,
Pacifica, California; Geological Society of America, in Reviews in engineering
geology, volume VII, Debris flows/avalanches: process recognition, and mitigation,
p.181-199.
State of California, 2006, Civil Code, Sections 895 et seq.
Tan, S.S., and Giffen, D.G., 1995, Landslide hazards in the northern part of the San Diego
metropolitan area, San Diego County, California, scale 1:24,000, DMG Open-File
Report 95-04.
Tan, S.S., and Kennedy, M.P., 1996, Geologic maps of the northwestern part of San Diego
County, California plate 1, geologic map of the Oceanside, San Luis Rey, and San
Marcos 7.5' quadrangles, San Diego County, California, scale 1:24,000, DMG Open-
File Report 96-02.
United States Department of Agriculture, 1953, Black and white aerial photographs,
AXN-8M-70 and AXN-8M-71, and AXN-8M-100to 102.
Wilson, K.L., 1972, Eocene and related geology of a portion of the San Luis Rey and
Encinitas quadrangles, San Diego County, California: unpublished masters thesis,
University of California, Riverside.
Robertson Family Trust Appendix
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