HomeMy WebLinkAboutCT 05-10; POINSETTIA PROPERTIES THE TIDES; GEOTECHNICAL MODEL LOT REPORT OF ROUGH GRADING; 2011-07-12ni i1:v ip4
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July 12;2011
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:J Ir1 Geotechnical Environmental and Materials Testing Consultants
I JJ BETTER PEOPLE .BETTER SERVICE. BETTERRESULTS I.J
Project No. 10707-30A
I .Mr. DarrenBolton -
K. HOVNANIAN HOMES .
2525 Campus Drive
Irvine, CA 92612
Subject:
Geotechnical Model Lot Report of Rough Grading, The Tides Residential
Development, Lots 16 through 21, Located on the Southwest Corner of Poinsettia
Lane and Lówder Lane, City of Carlsbad, San Diego County, California
INTRODUCTION
- Per your authorization, Earth-Strata, Inc. has provided observations and testing services during rough
grading for the proposed The Tides residential development, Lots 16 through 21, located on the
I southwest corner of Poinsettia Lane and Lowder Lane, in the City of Carlsbad, San Diego County,
California. This report summarizes the geotechnical conditions observed and tested during rough
grading. Conclusions and recommendations with regard to the suitability of the grading for the proposed
I project are provided herein, along with foundation design recommendations based on the earth materials
present at the completion of grading.
'Grading commenced in order to develop 6 building pads for construction of one- and/or two-story
structures. The proposed development will consist of single family residences utilizing slab on grade,
wood or steel-framed construction. Grading operations began in May 2011 and were completed in July
2011. .
REGULATORY COMPLIANCE
Observations and selective testing have been performed by representatives of Earth-Strata, Inc. during
the removal and recompaction of low-density near surface earth materials. Our services were performed
in general accordance with the recommendations presented in the referenced reports (see References),
the grading code of the reviewing agency, and as dictated by conditions encountered in the field. The
earthwork described herein has been reviewed and is considered adequate for the construction now
planned. The recommendations presented in this report were prepared in conformance with generally
accepted professional engineering practices in this area at the time of this report and no further warranty
is expressed or implied.
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I EARTH STRATA INC 26047 JEFFERSON AVENUE SUITE C MURRIETA CA 92562 OFFICE (951) 4614028 FAX (951)461-4058 WWW EARTH STRATA COM
BETTER PEOPLE- BETTER SERVICE - BETTER RESULTS
ENGINEERING GEOLOGY
Geologic Units
Earth materials noted during grading operations included topsoil, previously placed artificial fill and old
paralic deposits.
Geologic Structure
Geologic conditions exposed during grading operations were observed by Earth-Strata, Inc. The alluvium
is generally massive to horizontally layered and lacks significant structural planes.
Groundwater
Groundwater was not encountered during grading operations.
Faulting
No evidence of significant faulting was observed during grading operations.
EARTHWORK OBSERVATIONS AND DENSITY TESTING
Site Clearing and Grubbing
Prior to grading, all trees, brush, shrubs, and grasses were stripped and removed from the compacted fill.
Ground Preparation
Removals throughout most of the site ranged from approximately 4 to 7 feet below original grades, with
locally deeper removals.
Prior to placing compacted fill, the exposed bottom surfaces were scarified to depths of 6 to 8 inches,
I watered or air dried as necessary to achieve near optimum moisture content and then compacted to a
minimum relative compaction of 90 percent.
Oversize Rock
Oversize rock, generally greater than 1 foot in maximum dimension, was not encountered during the
grading operations.
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. Fill Placement and Testing
All fills were placed in lifts restricted to approximately 6 to 8 inches in maximum thickness; watered or
air dried as necessary to achieve near optimum moisture content, then compacted to a minimum of 90
I percent of the maximum dry density by rolling with a bulldozer, sheepsfoot, or loaded scrapers. The
maximum vertical depth of compacted fill as a result of grading within the proposed building pads is
approximately 11 feet.
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Benching into competent earth materials was observed during fill placement and compaction operations.
Field density and moisture content tests utilizing nuclear gauge methods were performed in accordance
with ASTM Test Methods D2922 and D3017. Field density and moisture content tests conducted utilizing
sand cone methods were performed in accordance with ASTM Test Method D1556. Visual classification
of theearth-mater-ial&-in-t-he-field was the basis for determining which maximum dry density value was
I applicable for a given density test. Test results are presented in Table 1 and test locations are shown on
the enclosed As-Graded Geotechnical Map, Plate 1. A summary of maximum and minimum fill
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thicknesses has been provided in Table 2 - Lot Summary.
Compacted fills were tested to verify that a minimum of 90 percent of the maximum dry density had been
achieved. At least one density test was taken for each 1,000 cubic yards and/or for every 2 vertical feet of
I compacted fill placed. The actual number of tests taken per day varied depending on the site conditions
and the quantity and type of equipment utilized. When field density tests yielded results less than the
minimum required density, the approximate limits of the substandard fill were established The
I substandard area was then reworked (most common) or removed, moisture conditioned, recompacted,
and retested until the minimum density was achieved. In most cases, failed density tests were noted then
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retested in the same general vicinity at nearly the same elevation as the failed test.
Slopes -
I Slopes constructed within thesubject property consist of 2:1 (h:v) compacted fill and slopes varying to a
maximum height of 10 feet.
I LABORATORY TESTING
1 Maximum Dry Density
Maximum dry density and optimum moisture content for representative earth materials noted during
I grading operations were determined using the guidelines of ASTM Test Method D 1557-00. Pertinent test
values are summarized in Appendix B.
I Expansion Index Tests
Expansion index tests were performed on representative earth materials sampled near finish grade for
select building pads using the guidelines of ASTM D 4829-03 Test results are summarized in Appendix B
Soluble Sulfate- Analyses
The soluble Jfate content of select samples was determined using the guidelines of California Test
Method(CTM).4.1.7. .Testresult are summarized in Appendix B.
Chloride
Chloride content of select samples was determined using the guidelines of CTM 422. Test results are
summarized in Appendix B.
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Minimum Resistivity and pH
Minimum resistivity and pH tests of select samples were determined using the guidelines of CTM 643. Test
results are summarized in Appendix B. -
POST GRADING CONSIDERATIONS
Slope Landscaping and Maintenance
Control of site drainage is important for the performance of the proposed project. Engineered slopes
should be landscaped with deep rooted, drought tolerant, maintenance free plant species, as
recommended by the project landscape architect. Unprotected slopes are highly susceptible to erosion
and surficial slumping. Therefore -to.-reduce.this-potential, we recommend that the slopes be covered
with an erosion inhibitor until healthy plant growth is well established. To further reduce the potential
for surficial instability, measures to control burrowing rodents should be performed as well.
Site Drainage
Adequate slope and building pad diämnáéi:éntiaI for the long têrni Ffor:ma.ñof_thT&tibject site.
The gross stability of graded slopes should not be adversely affected, provided all drainage provisions are
properly constructed and maintained. Roof gutters are recommended for the proposed structures. Pad
and roof drainage should be collected and transferred to driveways, adjacent streets, storm-drain
facilities, or other locations approved by the building official in non-erosive drainage devices. Drainage
should not be allowed to pond on the pad or against any foundation or retaining wall. Drainage should
not be allowed to flow uncontrolled over any descending slope. Planters located within retaining wall
backfill should be sealed to prevent moisture intrusion into the backfill. Planters located next to raised
floor type construction should be sealed to the depth of the footings. Drainage control devices require
periodic cleaning, testing, and maintenance to remain effective. -.
At a minimum, pad drainage should be designed at the minimum gradients required by the CBC. To
divert water away from foundations,-the ground surface adjacent to foundationsshou1dbegraded at the
minimum gradients required per the CBC. -
Utility Trenches - - - - -
All utility trench backfill should be tëdtda minimum of 90 percehtdfhiThxithth y density
determined by ASTM D-1155.7 ortiiiiyieiich backfill-inpavemenLaras-the pp_ej inches of
subgrade materials should be compacted,to.95cent of the maximum drIdi fidêiefmiiid by ASTM
D 1557-00 This includes withinsh iitrcright-of ways, utility easnjentsi er1Qotings sidewalks,
driveways and building floor slabs,as..welLaswithin or adjacent to any slopes.Backfi1l:should be placed
in approximately 6 to 8 inch m ax- inium loose lifts and then mechanically ?npdedh a hydro-
hammer, rolling with a sheepsfoot, pneumatic tampers, or similar equipment. The utility trenches should
be tested by the project geotechnical engineei or their representative to viñfyñiñiñiuñiompaction
requirements are obtained.
In order to minimize the penetration of moisture below building slabs, all utility trenches should be
backfilled with compacted fill, lean concrete, or concrete slurry where they undercut the perimeter
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foundation. 'Utility trenches that are proposed parallel to any building footings (interior and/or exterior
trenches), should not be located within a 1:1 (h:v) plane projected downward from the outside bottom
edge of the footing.
I FOUNDATION DESIGN RECOMMENDATIONS
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General
Conventional foundations are recommended for support of the proposed structures. Foundation
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recommendations are provided herein.
Allowable Bearing Values
An allowable bearing value of 2,000 pounds per square foot (psf) is recommended for design of 24 inch
square pad footings and 12 inch wide continuous footings founded at a minimum depth of 12 inches
below the lowest adjacent final grade. This value may be increased by 20 percent for each additional
1-foot of width and/or depth to a maximum value of 2,500 psf. Recommended allowable bearing values
include both dead and frequently applied live loads and may be increased by one third when designing
for short duration wind or seismic forces.
Settlement
Based on the settlement characteristics of the earth materials that underlie the building sites and the
anticipated loading, we estimate that the maximum total settlement of the footings will be less than
approximately 3/4 inch. Differential settlement is expected to be about ½ inch over a horizontal distance
of approximately 20 feet, for an angular distortion ratio of 1:480. It is anticipated that the majority of the
settlement will occur during construction or shortly after the initial application of loading.
'I The above settlement estimates are based on the assumption that the construction is performed in
accordance with the recommendations presented in this report and that the project geotechnical
consultant will observe or test the earth material conditions in the footing excavations.
I Lateral Resistance
Passive earth pressure of 250 'psf per foot of depth to a maximum value of 2,500 psf may be used to
establish lateral bearing resistance for footings. A coefficient of friction of 0.36 times the dead load forces
may be used between concrete and the supporting earth materials to determine lateral sliding resistance.
I The above values may be increased by one-third when designing for short duration wind or seismic
forces. When combining passive and friction for lateral resistance, the passive component should be
reduced by one third. In no case shall the lateral sliding resistance exceed one-half the dead load for clay,
I I sandy clay, sandy silty clay, silty clay, and clayey silt.
The above lateral resistance values are based on footings for an entire structure being placed directly
against compacted fill.
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Structural Setbacks
Structural setbacks are required per the 2010 California Building Code (CBC). Additional structural
setbacks are not required due-to geologic or geotechnical conditions within the site. Improvements
constructed incloseproximityto natural or properly engineered and compacted slopes can, over time, be
affected by natural processes .including gravity forces, weathering, and long term secondary settlement.
As a result, the CBC requires that buildings and structures be setback or footings deepened to resist the
influence of these processes.
For structures that are planned near ascending and descending slopes, the footings should be embedded
to satisfy the requirements presented in the CBC, Section 1808.7 as illustrated in the following
Foundation Clearances From Slopes diagram.
- FOUNDATION CLEARANCES FROM SLOPES
2010 CALIFORNIA BUILDING CObE
BUILbING SETBACK DIMENSIONS
- .8ET7L'IPECLE.ETttR8ERtXf.
FAM QFOQTINGN
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When determining the required clearance from ascending slopes with a retaining wall at the toe, the
height of the slope shall be measured from the top of the wall to the top of the slope. The structural
setback for pools may be reduced by one-half.
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Footing Observations - -
Prior to the placement of forms, concrete, or steel, all foundation excavations should be observed by the
geologist, engineer, or his representative to verify that they have been excavated into competent bearing
I materials. The excavations should be moistened, cleaned of all loose materials, trimmed neat, level and
square and any moisture softened earth materials should be removed prior to concrete placement.
Earth materials from foundation excavations should not be placed in slab on grade areas unless the
materials are tested for expansion potential and compacted to a minimum of 90 percent of the maximum
dry density.
Expansive Soil Considerations -
Laboratory test results indicate onsite earth materials exhibit an expansion potential of VERY LOW as
classified in accordance with 2010 CBC Section 1803.5.3 and ASTM D4829-03. The following
recommendations should be considered the very minimum requirements, for the earth materials tested.-
It is common practice for the project architect or structural engineer to require additional slab thickness,
footing sizes, and/or reinforcement.
Very Low Expansion Potential (Expansion Index of 20 or Less)
Our laboratory test results indicate that the earth materials onsite exhibit a VERY LOW expansion
potential as classified in accordance with 2010 CBC Section 1803.5.3 and ASTM D 4829-03. Since the
onsite earth materials exhibit expansion indices of 20 or less, the design of slab on ground foundations is
exempt from the procedures outlined in Sections 1808.6.1 and 1808.6.2.
Footings -
Exterior continuous footings may be founded at the minimum depths below the lowest
adjacent final grade (i.e. 12 inch minimum depth for one-story, 18 inch minimum depth for
two-story, and 24 inch minimum depth for three-story construction). Interior continuous
footings for one-, two-, and three-story construction may be founded at a minimum depth of 12
inches below the lowest adjacent final grade. All continuous footings should have a miriihiIñi'
width of 12, 15, and 18 inches, for one-, two-, and three-story structures, -respective1ypef
Table 1809.7 of the 2010 CBC and should be reinforced with a minimum of tw6 (2) N0'4 -
one (1) top and one (1) bottom.
Exterior pad footings intended to support roof overhangs, such as second story decks, patio
covers and similar construction should be a minimum of 24 inches square and founded at a
minimum depth of 18 inches below the lowest adjacent final grade. No special reinforcement
of the pad footings will be required.
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Building Floor Slabs
Building floor slabs should be a minimum of 4 inches thick and reinforced with a minimum of
No. 3 bars spaced a maximum of 24 inches on center, each way. All floor slab reinforcement
should be supported=on=concrete chairs or bricks to ensure the desired placement .atmid--
depth.
Interior floor slabs, within living or moisture sensitive areas, should be underlain by a
minimum 10-mil thick moisture/vapor barrier to help reduce the upward migration of
moisture from the underlying earth materials. The moisture/vapor barrier used should meet
the performance standards of an ASTM E 1745 Class A material, and be properly installed in
accordance with AC! publication 318-05. It is the responsibility of the contractor to ensure
that the moisture/vapor barriers are free of openings, rips, or punctures prior to placing
concrete. As an option for-additional moisture reduction, higher strength concrete, such as a
minimum 28-day compressive strength of 5,000 pounds per square inch (psi) may be used.
Ultimately, the design Thf the 'moisture/vapor barrier system and recommendations for
concrete placement and curing are the purview of the foundation engineer, taking into
consideration the project requirements provided by the architect and owner.
Garage floor slabs -rnnimum of 4 inches thick and should be reinforced in a similar - - --
I manner as living area-floor slabs. Garage floor slabs should be placed separately from adjacent
wall footings with a positive separation maintained with % inch minimum felt expansion joint
materials and quartered with weakened plane joints. A 12 inch wide turn down founded at the
I same depth as adjacent footings should be provided across garage entrances. The turn down
should be reinforced with a minimum of two (2) No. 4 bars, one (1) top and one (1) bottom.
The subgrade earth materials below all floor slabs should be pre-watered to promote uniform
curing of the concrete and minimize the development of shrinkage cracks, prior to placing
concrete. The pre-watering should be verified by Earth-Strata during construction.
Post Tensioned Slab /Foundation Design Recommendations
In lieu of the proceeding foundation recommendations, post tensioned slabs may be used to support the
proposed structures. We recommend that the foundation engineer design the foundation system using
the Post Tensioned Foundation Slab Design table below. These parameters have been provided in
general accordance with Post Tensioned Design. Alternate designs addressing the effects of expansive
earth materials are allowdrOTrCBC Section 1808.6.2. When utilizing these parameters, the
foundation engineer should=design=the=foundation system in accordance with the allowable deflection
criteria of applicable codes d thereqtiirements of the structural engineer/architect. -
It should be noted that the post-tensioned-design methodology is partially based on the assumption that
soil moisture changes around and underneath post tensioned slabs, are influenced only by climate
conditions. Soil moisture change below slabs is the major factor in foundation damages relating to
expansive soil. However, the design methodology has no consideration for presaturation, owner
irrigation, or other non-climate related influences on the moisture content of subgrade earth materials.
In recognition of these factors, we modified the geotechnical parameters determined from this
methodology to account for reasonable irrigation practices and proper homeowner maintenance.
Additionally, we recommend that prior to excavating footings, slab subgrades be presoaked to a depth of
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12 inches and maintained at above optimum moisture until placing concrete. Furthermore, we
recommend that the moisture content of the earth materials around the immediate perimeter and below
the slab be presaturated to at least 1% above optimum moisture content just prior to placing concrete.
The pre-watering should.be verifiedand tested by Earth-Strata during construction.
The following geotechnical parameters assume that areas adjacent to the foundations, which are planted
and irrigated, will be desigtied with proper drainage to prevent water from ponding. Water ponding near
the foundation causes significant moisture change below the foundation. Our recommendations do not
account for excessive irrigation and/or incorrect landscape design. Planters placed adjacent to the
foundation, should be designed with an effective drainage system or liners, to prevent moisture
infiltration below the foundation. Some lifting of the perimeter foundation beam should be expected
even with properly constructed planters. Based on our experience monitoring sites with similar earth
materials, elevated - moisturecontents below the foundation perimeter due to incorrect landscaping
Irrigation or maintenancecan_result in uplift at the perimeter foundation relative to the central portion
of
Future owners shoüld biif5ned and educated of the importance in maintaining a consistent level of
moisture within the earth materials around the structures. Future owners should also be informed of the
potential negativeconsequences of either excessive watering, or allowing expansive earth materials to
become -too. dry-.Earth-mater-ials will shrink as they dry, followed by swelling during the rainy winter
season, or whenirrigationisresumed. This will cause distress to site improvements and structures.
Post Tensioned Foundation Slab Design
PARAMETER : VALUE
Expansion Index Very Low'
Percent Finer than. 0.001mminthe Fraction Passing the No. 200 -
Sieve <20 percent (assumed)
Ty5e bfClä9MiiiFl Montmorillonite (assumed)
Thornthwaite Moisture Index - -20
Depth to Constant Soil Süctioi"i 7 feet
Constant Soil Suction P.F. 3.6
Moisture Velocity --- - - 0.7 inches/month
Center Lift Edge moisture variation distance, em -
-------Centerlift, Ym - --
5.5 feet
.- 1.5 inches
Edge Lift -r Edge moisture variation distance em
.Edge lifty_.
2.5 feet
0.4 inches
Soluble Sulfate..Content_ or.,Design..of Concrete Mixtures in
Contact with Earth Negligible
Modulus of SubgradeReaction k(assuming presaturation as
indicated below) 200 ci . p
Minimum Perimeter Foundation Embedment 12
Under Slab Moisture/Vapor Barrier and Sand Layer 10-mil thick moisture/vapor barrier meeting the
requirements of a ASTM E 1745 Class A material
Design obtàinèd b31 laboratory testing. -
Recommendations for foundation reinforcement are ultimately the purview of the foundation/structural engineer based
upon the geotechnical criteria presented in this report, and structural engineering considerations.
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Corrosivity
Corrosion is defined by the National Association of Corrosion Engineers (NACE) as "a deterioration of a
substance or its properties because of a reaction with its environment." From a geotechnical viewpoint,
the "substances" are the reinforced concrete foundations or buried metallic elements (not surrounded by
concrete) and the "environment" is the prevailing earth materials in contact with them. Many factors can
contribute to corrosivity, including the presence of chlorides, sulfates, salts, organic materials, different
oxygen levels, poor drainage, different soil types, and moisture content. It is not considered practical or
realistic to test for all of the factors which may contribute to corrosivity.
The potential for concrete exposure to chlorides is based upon the recognized Caltrans reference
standard "Bridge Design Specifications", under Subsection 8.22.1 of that document, Caltrans has
determined that "Corrosive water or soil contains more than 500 parts per million (ppm) of chlorides".
Based on limited preliminary laboratory testing, the onsite earth materials have chloride contents-less.-
than 500 ppm As such, specific requirements resulting from elevated chloride contents!-aie not required -
Specific guidelines for concrete mix design are provided in 2010 CBC Section 1904.5 and ACI 318, Section
4.3 Table 4.3.1 when the soluble sulfate content of earth materials exceeds 0.1 percent by weight. Based
on limited preliminary laboratory testing, the onsite earth materials are classified in accordance with
Table 4.3.1 as having a negligible sulfate exposure condition. Therefore, structural concrete in contact
with onsite earth materials should utilize Type I or II.
Based on our laboratory testing of resistivity, the onsite earth materials in contact with buried steel
should be considered corrosive. Additionally, pH values below 9.7 are recognized as being corrosive to
most common metallic components including, copper, steel, iron, and aluminum. The pH values for the
earth materials tested were lower than 9.7. Therefore, any steel or metallic materials that are exposed to
the earth materials should be encased in concrete or other measures should be taken to provide
corrosion protection. - -
If building slabs are to be post tensioned, the post tensioning cables should be encased in concrete and/or
encapsulated in accordance with the Post Tensioning Institute Guide Specifications. Post tensioning cable -
end plate anchors and nuts also need to be protected if exposed. If the anchor plates and nuts are in a
recess in the edge of the concrete slab, the recess should be filled in with a non-shrink, non-porous,
- - - moisture-insensitive epoxy grout so that the anchorage assembly and the end of the cable are completely
encased and isolated from the soil. A standard non-shrink, non-metallic cementitious grout maybe used - -
only when the post tension anchoring assembly is polyethylene encapsulated similar t thtffeFdby
Hayes Industries, LTD or O'Strand, Inc. -
The test results for corrosivity are based on limited samples in accordance with the current standard of-.
care. Laboratory test results are presented in Appendix B. - -
CONCRETE FLAT WORK
I Thickness and Joint Spacing
Concrete sidewalks and patio type slabs should be at least 31h inches thick and provided with
construction or expansion joints every 6 feet or less, to reduce the potential for excessive cracking.
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Concrete driveway slabs should be at least 4 inches thick and provided with construction or expansion
joints every 10 feet or less.
Subgrade Preparation
In order to reduce the potential- for unsightly cracking, subgrade earth materials underlying concrete
flatwork should be compacted to a minimum of 90 percent of the maximum dry density and then
moistened to at least optimum or slightly above optimum moisture content. This moisture should extend
to a depth of at least 12 inches below subgrade and be maintained prior to placement of concrete. Pre-
watering of the earth materials prior to placing concrete will promote uniform curing of the concrete and
minimize the development of shrinkage cracks. The project geotechnical engineer or his representative
should verify the density and moisture content of the earth materials and the depth of moisture
penetration-prior to placing concrete. - ------
Cracking ithii -côñcretff ofki iftn-a-result of factors such as the use of too high a water to cement - -
ratio and/or inadequate steps taken to prevent moisture loss during the curing of the concrete. Concrete
distress can be reduced by proper concrete mix design and proper placement and curing of the concrete.
Minor cracking within concrete flatwork is normal and should be expected.
POST GRADING OBSERVATIONS AND TESTING
It is the property owner's sole responsibility to notify Earth-Strata at the appropriate times for
observation and testing services. Earth-Strata can not be responsible for any geotechnical
recommendations where the appropriate observations and testing have not been performed. It is of the
utmost importance that the owner or their representative request observations and testing for at least
the following phases of work.
StructureConstruction - - - -
- . Observe all foundatiorj excavations prior to placement of concrete or steel to verify adequate
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depth and competent bearing conditions.
If necessary, re-observe all foundation excavations after deficiencies have been corrected. - -
I Retaining Wall Constr ctlön -
Observe all fouwdati xcavati6ns prior to placement of concrete or steel to verify adequate
I depth and competent bearing conditions
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. If necessary, re-observe all foundation excavations after deficiencies have been corrected.
Observe and verify proper installation of subdrain systems prior to placing retaining wall
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backfill. - -
Observe and test retaining wall backfill operations.
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Garden Walls
Observe all foundation excavations prior to placement of concrete or steel to verify adequate
depth and competent bearing conditions.
I . If necessary, re-observe all foundation excavations after deficiencies have been corrected.
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Exterior Concrete Flatwork Construction
Observe and test subgrade earth materials below all concrete flatwork to verify recommended
density and moisture content.
Utility Trench Backfill
I • Observe and test all utility trench backfill operations.
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Re-Grading
Observe and test the placement of any additional fill materials placed onsite.
GRADING AND CONSTRUCTION RESPONSIBILITY
It is the responsibility of the contractor or his subcontractors to meet or exceed the project specifications
for grading and construction. The responsibilities of Earth-Strata did not include the supervision or
direction of the contractor's personnel, equipment, or subcontractors performing the actual work. Our
field representative onsite was intended to provide the owner with professional advice, opinions, and
recommendations based on observations and limited testing of the contractor's work. Our services do
not relieve the contractor or his subcontractors of their responsibility, should defects in their work be
discovered. The conclusions and recommendations herein are based on the observations and test results
for the areas tested, and represent our engineering opinion as to the contractor's compliance with the
project specifications.
REPORT LIMITATIONS
U This report has not been prepared for use by parties or projects other than those named or described
herein. This report may not contain sufficient information for other parties or other purposes. Our
I services were performed using the degree of care and skill ordinarily exercised, under similar
-circumstances, by reputable soils engineers and geologists, practicing at the time and location this report
was prepared. No other warranty, expressed or implied, is made as to the conclusions and professional
; I advice included in this report.
Earth materials vary in type, strength, and other geotechnical properties between points of observation
I and testing. Groundwater and moisture conditions can also vary due to natural processes or the works of
man on this or adjacent properties.
I This report was prepared with the understanding that it is the responsibility of the owner or their
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I representative, to ensure that the conclusions and recommendations contained herein are brought to the
attention of the other project consultants and are incorporated into the plans and specifications. The
owners' contractor should properly implement the conclusions and recommendations during
construction and notify the owner if they consider any of the recommendations presented herein to be
unsafe or unsuitable.
I Earth-Strata sincerely appreciates the opportunity to provide our services and advice on this project.
Respectfully presented,
]EARTlHlSTRATA, ]INC.
Chad E. Welke, PG, CEG, PE
Principal Geologist/Engineer OFC I +Stepenoole, PE, GE C6 CD
Principal Engineer
I CW/SMP/am OF
I Attachments: Appendix A - References
Appendix B - Laboratory Procedures and Test Results
Table 1 - Summary of Field Density Tests
- I Table 2 - Lot Summary
Plate 1 - As-Graded Geotechnical Map
1 Distribution: (6) Addressee
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APPENDIX A
REFERENCES
APPENDIX A
REFERENCES
California Building Standards Commission, 2010, 2010 California Building Code, California Code of
Regulations Title 24, Part 2, Volume 2 0f2, Based on 2009 International Building Code.
Earth-Strata, Inc., 2010, Preliminary Geotechnical Interpretive Report, Proposed 29-Lot Residential
Development, Located on the Southwest Corner of Poinsettia Lane and Lowder Lane, City of
Carlsbad, Riverside County, California, dated May 11.
National Association of Corrosion Engineers, 1984, Corrosion Basics An Introduction, page 191.
Southern California Earthquake Center (SCEC), 1999, Recommended Procedures for Implementation of
DMG Special Publication 117, Guidelines for Analyzing and Mitigating Liquefaction Hazards in
California, March.
-1U41IJ1Do]
LABORATORY PROCEDURES AND TEST
RESULTS
APPENDIX B
Laboratory Procedures and Test Results
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Laboratorytesting pràvidedquantitative and qualitative data involving
representative earth materials selected for testing.. The representative sampleswere-testedingeneral
accordance with American Society for Testing and Materials ,(ASTM) procedures and/or California-Test Methods;
(CTM).
Soil Classification: Earth materials encountered during exploration were classified and logged in -. -
general accordance with the Standard Practice for Description and Identification of Soils (Visual:
Manual Procedure) of ASTM D 2488. Upon completion of laboratory testing sample descriptions were
reconciled to reflect laboratory-jest results with regard to ASTM D.2487.._
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-,
-=--; Maximum Density Tests: 'The maximum dry density and optimummoisturecontent of representative -"
samples were detminediiiñI the guidelines of ASTM D 1557 The fieft. f-e-s—ults. are
table below.
SAMPLE—.—___
NUMBER - - -
_ MATERIAL
DESCRIPTION
MAXIMUM.DRY-
DENSITY (pct)--
OPTIMUM;MO-IS-TURE-.
CONTENT:(%) -.
I 1 I Silty Sand 1 126.0 I 8.0
Expansion Index: The expansion potential of representative samples was evaluated using the
guidelines of ASTM D 4829. The test results are presented in the table below.
SAMPLE MATERIAL
LOCATION---DESCRIPTION.
EXPANSION INDEX EXPANSION POTENTIAL
Lot 16 through 18@01-feet i Silty Sand . 3 -.- Vir L'TJ
Lot 19 through 21,@ 0-1 feet . Silty Sand 3 . . - --"'VeryLow .-
Minimum Resistivity and p11-Tests Minimum resistivityand pH tests :of:selectsãrnTples:were_
perfoiid i tluidlire CTM 643 The test results are
- - . • 1_- - •.. ..'..4 _____-
- - - SAMPLE _ MATERIAL - - - - -- -
- pH j MINIMUMRESISTIVITY.
- iLOCATION DESCfflPTION: _()__
Lot 16 through18401-fét - Silty Sand' : -
Lot 19 through 21 @ 0-1 feet- Silty Sand
liz .
7 8
-----. 1;3tJU---
-----
--
Soluble Sulfate: The soluble sulfate content of select samples was determined using the guidelines of
CTM 417. The test results are presented in the table below.
SAMPLE MATERIAL SULFATE CONTENT
LOCATION DESCRIPTION (% by weight) SULFATE EXPOSURE
Lot 16 through 18 @ 0-1 feet Silty Sand 042 Negligible
Lot 19 through 21 @ 0-1 feet Silty Sand 0.34 Negligible
Chloride Content: Chloride content of select samples was determined using the guidelines of CTM
422. The test results are presented in the table below.
SAMPLE LOCATION MATERIAL-DESCRIPTION I CHLORIDECONTENT(ppm)
Lot 16 through 18@0-lfeet NO
Lot 19 through 21@0-lfeet ND
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TABLE 1
I SUMMARY OF FIELD DENSITY TESTS
I
Test
No.
Test
Type
Test
Date
Test
of Test Location Depth
(feet)
Soil
Type
Dry
Density
(pci)
Moisture
Content
(%)
Max.
Density
(pci)
Rel.
Density
(%)
- 15 N 05/05/11 CF Lot 16 Near Midline of Pad . -6 1 117.1 8.8 126.0 93
16 N 05/05/11 CF Lot 17 Near Midline ofRoad -6 1 122.2 7.9 126.0 97
17 N 05/05/11 CF Lot l8 Northwest l/4ofLot -6 1.. 122.2 8.0 126.0 97
18 N 05/05/11 CF Lot 19 Midline of Pad . -5 1 119.1 7.5 126.0 95
I 19 N 05/05/11 CF Lot 20 South Half West Side -5 1 116.7 7.1 126.0 93
20 N 05/05/11 CF Lot 21 Midline South Half of Pad -7 1 120.0 6.7 126.0 95
23 N 05/10/11 ..CF . Lot 20Toe of East Slope North End -3 1 115.4 6.6 126.0 92
24 N 05/10/11 CF Lot 21 Northeast 1/4 of Pad -5 1 117.7 5.7 126.0 93
I 25 N 05/10/11 CF Lot 20 Toe of East Slope - -2 '1 115.6 8.2 126.0 92
26 N 05/10/11 CF Lot 21 Mid/Midline .. -6 1 117.8 7.9 126.0 93
-N. .05/10/11 - CF Lot 17 Southwest Corner - -. -5 - 1. 115.4 7.4 126.0 92
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.27
28 -N 05/10/11 .CF Lot 17 Northeast Corner- -4 1 116.3 7.6 126.0 92
-
- 32 -N 05/10/11. CF Lot 17/18 Common Place ' ",' . . -5 1' . 116.0 8.8 126.0 92
33 N 05/10/11 CF Lot 17 Northwest Corner . -5 1 114.5 8.7 126.0 91
I ..N. 05/11/11 CF Lot 21 Northeast Corner . -4 1 113.7 5.9 126.0 90
54 N 05/11/11 CF Lot 21 Southwest Corner - -3 1- 113.9 6.0 126.0 90
55 N. .05/11/11 CF Lot 21 Southeast Corner . -2 - 114.9 7.5 126.0 91
-77 --N - -05/12/11 --CF Lot 16 Northwest Corner . . . . -5 1 . 114.0 6.0 126.0 90 U 78 N 05/12/11 CF Lot 18 Southwest Corner -4 1 116.1 8.3 126.0 92
81 . _N 05/13/11 . CF Lot 16 Midline East End . -5 1 116.6 6.7 126.0 93
82 N 05/13/11 CF Lot 16 Midline North End - -4 1 114.7 7.4 126.0 91
I 83 N 05/13/11 CF Lot 17/18 Common Place -4 1 120.3 7.0 126.0 95
84 . N 05/13/11 CF Lot 17 Mid Top of Slope West Side -3 1 122.4 7.8 126.0 97
85 N 05/13/11 CF Lot 18 Northeast Corner . -3 1 113.7 7.3 126.0 90
I 86 N 05/13/11 CF Lot 18 Midline -2 1 115.2 7.0 126.0 91
87 .N. 05/13/11 . CF Lo t 19 Southwest 1/4 of Pad . -2 . 1 117.1. 7.6 126.0 93
88 N 05/13/11 CF Lot 19 Shoal Court -1 1 115.5 7.7 126.0 92
U.. .89 N 05/13/11 CF... Lot 20 West Half of Pad (Midline)- - J-3 1 118.5 - 5.0 126.0 94
90 --N- 05/13/11 CF Lot 20 Top of Drive Midline -1 1 115.5 5.4 126.0 92
- 91 N. 05/13/111- CF' Lot 21 Top of West Slope NW Corner -2 1 . 114.0 5.4 126.0 90
92 N 05/13/11 :.CF . Lot 21 Top of West Slope Midline . -1 1 . 116.3 7.0 126.0 92
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.
.109 N- .05/19/11 CF Lot 21 Center of Pad East Side - FG - 1 107.3 6.4 126.0 85
113 - N .05/20/11 CF Lot 18 Midline . .- FG - 1 124.0 6.6 126.0 98
114.. -N, 05/20/11 CF . Lot 18atCul DeSac - - , FG 1 118.5 7.7 126.0 94
I. 115 . .N 05/20/11 CF , Lot 17 at Cul DeSac . FG . . _1 . 120.5 6.9 126.0 96
116 N 05/20/11 .CF Lot 17Midline8 North/ South P/L ,.FG 1 1156 74 1260 92
117 N 05/20/11 - CF - Lot 19 Midline on '18/19 P/L , , '• FG ' 1 122.8 .7.2 126.0 97
I 118 N 05/20/11 CF ' Lot 19 Midline of Pad ' ' . - FG - 1 119.2 7.6 126.0 95
119 , .N. 05/20/11. - CF: Lot 19 NE 1/4 of Pad at Lot 20 Drive ' FG :1 . .115.4 ' 6.6 126.0 92
-. 120 N. 05/20/11 CF Lot 70 inDriveway South Side Midline - FG .1. 114.4 8.2 126.0 91
121 N 05/20/11 CF Lot 20 Midline in Foot Print FG 1 123.4 7.2 126.0 98 U 122 J N 05/20/11 CF I Lot20ToeofEastSlopeMidline FG 1 117.0 7.0 126.0 93
I
U
N - Nuclear Test Method FG - Finish Grade Project No.: 10707-35A
I CF - Compacted Fill MAY 2011
•-
______ • --,-" ----- - ---.-----• .• -
______________ 7=77
Lot Number Maximum Fill Depth (It) Minimum Fill Thickness (It)
16 8 8
10 _ :10
10
_________ - rt J. - - -
20
rt -4.-rt ---r
3-
21 7 7
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- -
- •,-. - - - -.
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T TT1I IJTALE 2 -LOTSUMMARY
Project No. 11707-30A
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