HomeMy WebLinkAboutTract Map 3883 Lot 258 Geotechnical Feasibility
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GEOTECHNiCAL! FEASIBILITY STUDY
Boyd 5 Rsidence
Assessor's Parce Number: 919-190-014
Lot 258 otTract 83, Calle Torcida
City of Temecula, County of Riverside, California
Project Number: T3421-GFS
June 28, 2006
Prepared for:
Mr. Tony Boyd
30186 Channel Way Drive
Canyon Lake, California 92587
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Mr. Tony Boyd
Project Number: T3421-GFS
TABLE OF CONTENTS
Section Number and Title
Paae
1.0 SITE/PROJECT DESCRIPTION ......................................................................................1
1.1 Site Description ....................................................................................................1
1.2 Project Description ...............................................................................................2
2.0 FINDINGS............................. ........ ................. .......... ............................. ...... ................... 2
2.1 Site Review...........................................................................................................2
2.2 Laboratory Testing................................................................................................ 2
2.2.1 General.. ............. ........... ........... .... ........................ ....... ......... ..................2
2.2.2 Classification .... .... .... ...... ... .... .... .... ...... .... ........... ... .... ... ...... ..... ... ............ 2
2.2.3 Maximum Dry Density/Optimum Moisture Content Relationship Test.... 2
2.2.4 Expansion Potential. ......................... ..... ........................... .......... ....... .....3
2.2.5 Direct Shear Test.................................................................................... 3
2.2.6 Soluble Sulfates..... ...................... ............. .............................................. 3
2.3 Excavation Characteristics ...................................................................................3
3.0 ENGINEERING GEOLOGY/SEISMICITY .......................................................................3
3.1 Geologic Setting ...................................................................................................3
3.2 Seismic Hazards. ........ ...................................... ............................ .... ....................4
3.2.1 Surface Fault Rupture ............................................................................4
3.2.2 Liquefaction. .... .............. ................................................... ......................4
3.2.3 Seismically-Induced Landsliding............. ............... ........ ...... ..... ... ..... .... ..4
3.2.4 Seismically-Induced Flooding, Seiches and Tsunamis...........................4
3.3 Earth Materials .....................................................................................................5
3.3.1 Alluvium (Qal) .........................................................................................5
3.3.2 Pauba Formation Sandstone (Qps)........................................................5
4.0 EARTHWORK RECOMMENDATIONS ...........................................................................5
4.1 All Areas ............................................................................................................... 5
4.2 Oversize, Material..... ........ ............... ....... ......... ........ ................ .... ..... .......... ...... ..... 6
4.3 Structural Fill.............. ...................................... ........ ............. ........ ...... ..................6
4.4 Soil Expansion Potential....................................................................................... 7
4.5 Soluble Sulfate ..................................................................................................... 7
5.0 SLOPE STABILITY - GENERAl....................................................................................8
6.0 CONCLUSIONS AND RECOMMENDATIONS................................................................8
6.1 Foundation Design Recommendations ................................................................8
6.1.1 Foundation Size......................................................................................8
6.1.2 Depth of Embedment .............................................................................8
6.1.3 Bearing Capacity ....................................................................................8
6.1.4 Seismic Design Parameters ...................................................................9
6.1.5 Settlement ..............................................................................................9
6.2 Lateral Capacity......................... ................................ ................... .......... ..............9
EnGEN Corporation
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Mr. Tony Boyd
Project Number: T3421-GFS
TABLE OF CONTENTS
Section Number and Title
Paae
6.3 Slab-on-Grade Recommendations. ...................................................................... 9
6.4 Exterior Slabs .....................................................................................................10
7.0 RETAINING WAlL RECOMMENDATIONS.................................................................. 10
7.1 Earth Pressures..................................................................................................10
7.2 Retaining Wall Design ........................................................................................11
7.3 Subdrain .............................................................................................................11
7.4 Backfill................................................................................................................11
8.0 MISCELLANEOUS RECOMMENDATIONS..................................................................12
8.1 Utility Trench Recommendations........................................................................ 12
8.2 Finish Lot Drainage Recommendations .............................................................12
8.3 Planter Recommendations .................................................................................13
8.4 Supplemental Construction Observations and Testing ......................................13
8.5 Plan Review........................................................................................................13
8.6 Pre-Bid Conference............................................................................................13
8.7 Pre-Grading Conference ....................................................................................14
9.0 CLOSURE..................... ......... ..... ............ ............................... .................... .................. 14
APPENDIX:
TECHNICAl REFERENCES
LABORATORY TEST RESULTS
DRAWINGS
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June 28. 2006
Mr. Tony Boyd
30186 Channel Way Drive
Canyon Lake, California 92587
(951) 538-4662 I FAX (951) 244-4023
Regarding: GEOTECHNICAl FEASIBILITY STUDY
Boyd Residence
Assessor's Parcel Number: 919-190-014
Lot 258 of Tract 2883, Calle Torcida
City of Temecula, County of Riverside, California
Project Number: T3421-GFS
Reference:
1. Bratene Construction and Engineering, Grading Plan, Boyd Residence,
Calle Torcida, Temecula, California, plans dated April 19, 2006.
Dear Mr. Boyd:
In accordance with your request and signed authorization, a representative of this firm has visited
the subject site on September 2, 2005, to visually observe the surficial conditions of the subject lot
and to collect samples of representative surficial site materials. Laboratory testing was performed
on these samples. Test results and preliminary foundation recommendations for the construction
and grading of the proposed development are provided. It is our understanding that cut and fill
type. grading will take place for the proposed structural development. Based on this firm's
experience with this type of project, our understanding of the regional geologic conditions
surrounding the site, our review of in-house maps, and both published and unpublished reports,
subsurfa'ce exploration was not considered necessary. However, in lieu of subsurface exploration,
additional grading beyond that antiCipated in this report may be necessary depending on the
exposed conditions to be encountered during grading. If any changes are made to the
Referenced No. 1 Plans, they should be reviewed by this office so additional recommendations, if
necessary, can be prepared.
1.0 SITE/PROJECli DESCRIPTION
1.1 Site Description: The subject site consists of approximately 0.81-acres located on the
east side of Calle Torcida south of the intersection of Calle Torcida and La Sombra
Court, in the City of Temecula, County of Riverside, California. Topography on site is
gently sloping to the' south at gradients of approximately 5 to 10 percent. An east to
west flowing seasonal drainage is located on the southern side of the site, it lies
approximately 3-feet deeper than the surrounding topography. Vegetation on site
consists of native weeds and grasses, with some bushes and trees located along the
drainage. No structures are located on site.
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Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 2
1.2 Proiect Description: It is our understanding that the proposed development will consist
of a one or two story, wood-framed single family residence with a slab-on-grade
foundation. We are providing general grading and minimum footing recommendations
for the proposed development.
2.0 FINDINGS
2.1 Site Review: Based on our field reconnaissance, it appears that alluvium, and Pauba
Formation Sandstone underlie the site. Pauba Formation Sandstone was exposed in
the slope along the northeast property line and constitutes bedrock at the subject site.
The alluvium exposed at the ground surface was found to be dry and loose. Since no
subsurface exploration was performed for this study, the thickness and condition of the
alluvium is unknown.
2.2 laboratory Testina:
2.2.1 General: The results of laboratory tests performed on samples of earth material obtained
during the site visit are presented in the Appendix. Following is a listing and brief
explanation of the laboratory tests performed. The samples obtained during the field study
will be discarded 30 days after the date of this report. This office should be notified
immediately if retention of samples will be needed beyond 30 days.
2.2.2 Classification: The field classification of soil materials encountered during our site visit
were verified in the laboratory in general accordance with the Unified Soils Classification
System, ASTM D 2488-00, Standard Practice for Determination and Identification of Soils
(Visual-Manual Procedures).
2.2.3 Maximum Dry Densitv/Optimum Moisture Content Relationship Test: Maximum dry
density/optimum moisture content relationship determinations were performed on
samples of near-surface earth material in general accordance with ASTM 1557-02
procedures using a 4.0-inch diameter mold. Samples were prepared at various
moisture contents and compacted in five (5) layers using a 10-pound weight dropping
18-inches and with 25 blows per layer. A plot of the compacted dry density versus the
moisture content of the specimens is constructed and the maximum dry density and
optimum moisture content determined from the plot. .
EnGEN Corporation
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Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 3
2.2.4 Expansion Potential: Laboratory expansion tests were performed on samples of near-
surface earth materials in general accordance with CBC 18-2 procedures. In this testing
procedure, a remolded sample is compacted in two (2) layers in a 4.0-inch diameter mold
to a total compacted thickness of approximately 1.0-inch by using a 5.5 pound weight
dropping 12-inches and with 15 blows per layer. The sample should be compacted at a
saturation of between 49 and 51 percent. After remolding, the sample is confined under a
pressure of 144 pounds per square foot (psf) and allowed to soak for 24 hours. The
resulting volume change due to the increase in moisture content within the sample is
recorded and the Expansion Index (EI) is calculated.
2.2.5 Direct Shear Test (Remolded): Direct shear tests were performed on select samples of
near-surface earth material, which had been remolded to 90 percent of the maximum
density, in general accordance with ASTM D 3080-03 procedures. The shear machine is
of the constant strain type. The shear machine is designed to receive a 1.0-inch high,
2.416-inch diameter ring sample. Specimens from the sample were sheared at various
pressures normal to the face of the specimens. The specimens were tested in a
submerged condition. The maximum shear stresses were plotted versus the normal
confining stresses to determine the shear strength (cohesion and angle of internal friction).
2.2.6 Soluble Sulfates: Samples of near-surface earth material were obtained for soluble
sulfate testing for the site. The concentration of soluble sulfates was determined in
general conformance with California Test Method 417 procedures.
2.3 Excavation Characteristics: Excavation and trenching within the alluvium is anticipated
to be relatively easy. Excavation and trenching in the bedrock will be more difficult due to
the higher bedrock densities typically encountered in the area. A rippability survey was not
within the scope of our investigation. Based on our experience on similar projects near the
subject site, the bedrock is expected to be rippable with conventional grading equipment.
3.0 ENGINEERING 'GEOLOGY/SEISMICITY
3.1 Geoloaic settina: The site is located in the Northern Peninsular Range on the southern
sector of the structural unit known as the Perris Block. The Perris Block is bounded on the
northeast by the San Jacinto Fault Zone, on the southwest by the Elsinore Fault Zone, and
on the north by the Cucamonga Fault Zone. The southern boundary of the Perris Block is
not as distinct, but is believed to coincide with a complex group of faults trending
EnGEN Corporation
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Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 4
southeast from the Murrieta, California area (Kennedy, 1977). The Peninsular Range is
characterized by large Mesozoic age intrusive rock masses flanked by volcanic,
metasedimentary, and sedimentary rocks. Various thicknesses of alluvial and colluvial
sediments derived from the erosion of the elevated portions of the region fill the low-lying
areas. The earth materials encountered on the subject site are described in more detail in
subsequent sections of this report.
3.2 Seismic Hazards: Because the proposed development is located in tectonically active
southern California, it will likely experience some effects from earthquakes. The type or
severity of seismic hazards affecting the site is mainly dependent upon the distance to the
causative fault, the intensity of the seismic event, and the soil characteristics. The seismic
hazard may be primary, such as ground surface rupture and/or ground shaking, or
secondary, such as liquefaction or dynamic settlement.
3.2.1 Surface Fault Rupture: The site is not located within a State of California designated
Alquist-Priolo Earthquake Fault Zone. No faulting was observed during our site
reconnaissance. The nearest State designated active fault is the Elsinore Fault (Temecula
Segment), located approximately 4.0 kilometers (2.5 miles) to the southwest of the subject
site. This conclusion is based on literature review (Kennedy, 1977) and EnGEN
Corporation's field reconnaissance. Accordingly, the potential for fault surface rupture on
the site is very unlikely.
3.2.2 liauefaction: Based on Section 4.0, Earthwork Recommendations, of this report, and the
dense nature of the underlying bedrock, the potential for liquefaction at the site is
considered very low.
3.2.3 Seismicallv Induced landslidina: Due to the overall massive and dense nature of the
bedrock, and the low topographic relief on site, the probability of seismically induced
landsliding is considered very low.
3.2.4 Seismicallv Induced Floodina. Seiches and Tsunamis: Due to the absence of a
confined body of water in the immediate vicinity of the project site, the possibility of
seismically induced flooding or seiches is considered nil. Due to the large distance of the
project site to the Pacific Ocean, the possibility for seismically induced tsunamis to impact
the site is considered nil.
EnGEN Corporation
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Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 5
3.3 Earth Materials
3.3.1 Alluvium (Qal): Alluvium is exposed across the site. Surficially, the alluvium was found to
consist of silty fine-grained sand and was found to be dry and loose. Since no subsurface
exploration was performed for this study, the thickness and condition of the alluvium is
unknown.
3.3.2 Pauba Formation Sandstone (Qps): Pauba Formation Sandstone constitutes bedrock
at the subject site. It is not exposed on the subject site, however, it is exposed on the
adjacent northeastern property, and is interpreted to underlie the alluvium on the subject
site. The Pauba Formation Sandstone may potentially contain silts and clays which are
not apparent at the surface.
4.0 EARTHWORK RECOMMENDATIONS
4.1 All Areas:
1. All vegetation should be removed from areas to be graded and not used in fills. Any
undocumented fill should be removed and recompacted.
2. Removals of the alluvium in the vicinity of the proposed building should be
performed so that, at a minimum, the upper 3-feet of alluvium has been removed.
The removal bottoms should expose competent alluvium. Competent alluvium
alluvial bottoms should be defined as undisturbed removal bottoms which are at
least 85 percent compact. Undisturbed removal bottoms which are not at least 85
percent compact will require deeper removals. Actual removal depths should be
determined during grading under exposed conditions.
3. If the structure straddles a cut/fill transition, the cut and shallow fill portions should
be overexcavated. The cut and shallow fill portions should be overexcavated to a
depth equal to at least half the maximum fill thickness, with a minimum of 3-feet.
The overexcavation should extend beyond the perimeter of the structure a distance
equal to the overexcavation depth, with a minimum of 5-feet.
4. All exposed removal and overexcavation bottoms should be inspected by the Project
Geologist or his representative prior to placement of any fill. Dry, loose alluvium
should be removed to competent alluvium. All residual soils and weathered bedrock
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4.2
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Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 6
must be removed to competent bedrock. Bedrock bottoms should be probed to verify
competency.
5. The approved exposed bottoms of all removal areas should be scarified 12-inches,
brought to, near optimum moisture content, and compacted to a minimum of 90
percent relative compaction before placement of fill. Maximum dry density and
optimum moisture content for compacted materials should be determined according
to ASTM D 1557-02 procedures.
6. A keyway should be constructed at the toe of all fill slopes that are proposed on
natural grades of 5:1 (horizontal to vertical) or steeper. Keyways should be a
minimum of fifteen (15) feet wide (equipment width) and tilted a minimum of two
percent into the hillside. A series of level benches should be constructed into
competent alluvium on natural grades of 5: 1 (horizontal to vertical) or steeper prior to
placing fill.
7. All fill slopes should be constructed at slope ratios no steeper than 2: 1 (horizontal to
vertical). All cut slopes should be inspected by the Project Geologist to verify stability.
Cut slopes exposing loose soils may be considered unstable. Unstable cut slopes
may require flattening or buttressing.
Oversize Material: Oversize material is defined as rock, or other irreducible material with
a maximum dimension greater than 12-inches. Oversize material shall not be buried or
placed in fill unless location, materials, and placement methods are specifically accepted
by the Project Geotechnical Engineer. Placement operations shall be such that nesting of
oversize material does not occur, and such that oversize material is completely
surrounded by compacted fill (windrow). Alternative methods, such as water jetting or
wheel rolling with a backhoe may be required to achieve compaction in the fill materials
immediately adjacent to the windrow. Oversize material shall not be placed within ten (10)
vertical feet of finish grade, within fifteen (15) lateral feet of a finished slope face, or within
two feet of future utilities.
Structural Fill: All fill material, whether on-site material or import, should be accepted by
the Project Geotechnical Engineer andlor his representative before placement. All fill
should be free from vegetation, organic material, and other debris. Import fill should be no
more expansive than the existing on-site material, unless approved by the Project
EnGEN Corporation
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5.0
Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 7
Geotechnical Engineer. Approved fill material should be placed in horizontal lifts not
exceeding 6.0 to 8.0-inches in thickness, and watered or aerated to obtain near-optimum
moisture content (within 2.0 percent of optimum). Each lift should be spread evenly and
should be thoroughly mixed to ensure uniformity of soil moisture. Structural fill should
meet a minimum relative compaction of 90 percent of maximum dry density based upon
ASTM D 1557-02 procedures. Moisture content offill materials should not vary more than
2.0 percent of optimum, unless approved by the Project Geotechnical Engineer.
Soil Expansion Potential: Preliminary Expansion Index testing was performed, yielding
an EI of 11. This is classified as a very low expansion potential. Import soils or soils used
near finish grade may have a different EI. The bedrock can potentially contain significant
amounts of expansive silts or clays. Mixing of these silts and clays during grading could
affect the overall EI of the fill. If selective grading is desired in order to ensure that
expansive soils are not used near pad grade, this option should be discussed with this
firm and the grading contractor prior to grading the site. Final foundation design
parameters should be based on EI testing of near-surface soils and be performed at the
conclusion of rough grading. Those results should be forwarded and incorporated into
the final design by the Project Structural Engineer.
Soluble Sulfates: The test results indicate a negligible percentage of water-soluble
sulfates (less than 0.001% by weight). As a result, Type II cement may be used in
contact with the on-site soils.
SLOPE STABiliTY - GENERAL
It is our professional opinion that cut or fill slopes no taller than 30-feet and inclined at 2: 1
(horizontal to vertical) or flatter, will possess gross and surficial stability in excess of
generally accepted minimum engineering criteria (Factor of Safety at least 1.5) and are
suitable for their intended purpose, provided that proper slope maintenance procedures
are maintained. These procedures include but are not limited to installation and
maintenance of drainage devices and planting of slope faces to protect from erosion in
accordance with County of Riverside Grading Codes.
EnGEN Corporation
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Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 8
6.0 CONCLUSIONS AND RECOMMENDATIONS
6.1 Foundation Desian Recommendations: Foundations for the proposed structure may
consist of conventional column footings and continuous wall footings founded in
compacted fill. The recommendations presented in the subsequent paragraphs for
foundation design and construction are based on geotechnical characteristics and upon
a very low expansion potential for the supporting soils and should not preclude more
restrictive structural requirements. The Structural Engineer for the project should
determine the actual footing width and depth in accordance with the latest edition of the
California Building Code to resist design vertical, horizontal, and uplift forces and should
either verify or:amend the design based on final expansion testing at the completion of
grading.
6.1.1 Foundation Size: Continuous footings should have a minimum width of 12-inches.
Continuous footings should be continuously reinforced with a minimum of one (1) NO.4
steel reinforcing bar located near the top and one (1) No.4 steel reinforcing bar located
near the bottom of the footings to minimize the effects of slight differential movements
which may occur due to minor variations in the engineering characteristics or seasonal
moisture change in the supporting soils. Column footings should have a minimum width of
18-inches by 18-inches and be suitably reinforced, based on structural requirements. A
grade beam, founded at the same depths and reinforced the same as the adjacent
footings, should be provided across doorway and garage entrances.
6.1.2 Depth of Embedment: Exterior and interior footings founded in compacted fill should
extend to a minimum depth of 12-inches below lowest adjacent finish grade for single
story structures and 18-inches below lowest adjacent finish grade for two (2) story
structures.
6.1.3 Bearina Capacity: Provided the recommendations for site earth work, minimum footing
width, and minimum depth of embedment for footings are incorporated into the project
design and construction, the allowable bearing value for design of continuous and
column footings for the total dead plus frequently-applied live loads is 2,000 psf for
compacted fill. The allowable bearing value has a Factor of Safety of at least 3.0 and
may be increased by 33.3 percent for short durations of live and/or dynamic loading
such as wind or seismic forces.
EnGEN Corporation
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Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 9
6.1.4 Seismic Desian Parameters: The following seismic parameters apply:
Name of Fault: Elsinore Fault (Temecula Segment)
Type of Fault: Type B Fault
Closest Distance to Fault: 4.0 Kilometers (2.5 miles)
Soil Profile Type: So
6.1.5 Settlement: Footings designed according to the recommended bearing values and the
maximum assumed wall and column loads are not expected to exceed a maximum
settlement of 0.75-inch or a differential settlement of 0.5-inch.
6.2 lateral Capacitv: Additional foundation design parameters based on compacted fill for
resistance to static lateral forces, are as follows:
Allowable lateral Pressure (Equivalent Fluid Pressure), Passive Case:
Compacted Fill - 200 pcf
Allowable Coefficient of Friction: Compacted Fill - 0.35
Lateral load resistance may be developed by a combination of friction acting on the
base of foundations and slabs and passive earth pressure developed on the sides of the
footings and stem walls below grade when in contact with compacted fill. The above
values are allowable design values and may be used in combination without reduction in
evaluating the resistance to lateral loads. The allowable values may be increased by
33.3 percent for short durations of live and/or dynamic loading, such as wind or seismic
forces. For the calculation of passive earth resistance, the upper 1.0-foot of material
should be neglected unless confined by a concrete slab or pavement. The maximum
recommended allowable passive pressure is 5.0 times the recommended design value.
6.3 slab-on-Grade Recommendations: The recommendations for concrete slabs, both
interior and exterior, excluding PCC pavement, are based upon the anticipated building
usage and upon a very low expansion potential for the supporting material as
determined by Chapter 18 of the California Building Code. Concrete slabs should be
designed to minimize cracking as a result of shrinkage. Joints (isolation, contraction,
and construction) should be placed in accordance with the American Concrete Institute
(ACI) guidelines. Special precautions should be taken during placement and curing of
all concrete slabs. Excessive slump (high water/cement ratio) of the concrete and/or
improper curing procedures used during either hot or cold weather conditions could
result in excessive shrinkage, cracking, or curling in the slabs. It is recommended that
EoGEN Corporation
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7.1
Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 10
all concrete proportioning, placement, and curing be performed in accordance with ACI
recommendations and procedures. Slab-on-grade reinforcement and thickness should
be provided by the structural engineer based on structural considerations, but as a
minimum, it is !recommended that concrete floor slabs be at least 4-inches in nominal
thickness and reinforced with at least NO.3 reinforcing bars placed 24-inches on center,
both ways, placed at mid-height of the slab cross-section. Final expansion testing at
completion of grading could cause a change in the slab-on-grade recommendations. In
areas where moisture sensitive floor coverings are anticipated over the slab, we
recommend the use of a polyethylene vapor barrier with a minimum of 10.0 mil in
thickness be placed beneath the slab. The moisture barrier should be overlapped or
sealed at splices and covered top and bottom by a 1.0 to 2.0-inch minimum layer of
clean, moist (not saturated) sand to aid in concrete curing and to minimize potential
punctures.
6.4
Exterior Slabs: All exterior concrete slabs cast on finish subgrade (patios, sidewalks,
etc., with the exception of PCC pavement) should be a minimum of 4-inches nominal in
thickness. Reinforcing in the slabs and the use of a compacted sand or gravel base
beneath the slabs should be according to the current local standards. Subgrade soils
should be moisture conditioned to at least optimum moisture content to a depth of
12-inches immediately before placing the concrete.
RETAINING WAll RECOMMENDATIONS
Earth Pressures: Retaining walls backfilled with non-expansive granular soil (EI=O) or
very low 'expansive potential materials (Expansion Index of 20 or less) within a zone
extending upward and away from the heel of the footing at a slope of 0.5:1 (horizontal to
vertical) or flatter can be designed to resist the following static lateral soil pressures:
,Condition level Backfill 2:1 Slope
Active 30 oct 45 Dcf
At Rest 60 oct -
Further expansion testing of potential backfill material should be performed at the time of
retaining wall construction to determine suitability. Walls that are free to deflect 0.01
radian at the top may be designed for the above-recommended active condition. Walls
that need to be restricted from this amount of movement should be assumed rigid and
designed for the at-rest condition. The above values assume well-drained backfill and no
EnGEN Corporation
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Project Number: T3421-GFS
June 2006
Page 11
buildup of hydrostatic pressure. Surcharge loads, dead and/or live, acting on the backfill
behind the wall should also be considered in the design.
Retainina Wall Desian: Retaining wall footings should be founded to the same depths
into firm, competent, undisturbed, natural soil as standard foundations and may be
designed for an allowable bearing value of 2,000 psf when founded in compacted fill (as
long as the resultant force is located in the middle one-third of the footing). Allowable
static lateral bearing pressure of 200 psf/ft may be used in compacted fill. An allowable
sliding resistance coefficient of friction of 0.35 is applicable for compacted fill. When using
the allowable lateral pressure and allowable sliding resistance, a Factor of Safety of 1.5
should be achieved.
Subdrain: A subdrain system should be constructed behind and at the base of retaining
walls equal to or in excess of 5-feet in height to allow drainage and to prevent the buildup
of excessive hydrostatic pressures. Gravel galleries and/or filter rock, if not properly
designed and graded for the on-site and/or import materials, should be enclosed in a
geotextile fabric such as Mirafi 140N, Supac 4NP, or a suitable substitute in order to
prevent infiltration of fines and clogging of the system. The perforated pipes should be at
least 4.0-inches in diameter. Pipe perforations should be placed downward. Gravel filters
should have volume of at least 1.0 cubic foot per lineal foot of pipe. For retaining walls
with an overall, height of less than 5-feet, subdrains may include weep holes with a
continuous gravel gallery, perforated pipe surrounded by filter rock, or some other
approved system. Subdrains should maintain a positive flow gradient and have outlets
that drain in a non-erosive manner.
Backfill: Backfill directly behind retaining walls (if backfill width is less than 3-feet) may
consist of 0.5, to 0.75-inch diameter, rounded to subrounded gravel enclosed in a
geotextile fabric such as Mirafi 140N, Supac 4NP, or a suitable substitute or a clean sand
(Sand Equivalent Value greater than 50) water jetted into place to obtain proper
compaction. If water jetting is used, the subdrain system should be in place. Even if water
jetting is used, the sand should be densified toa minimum of 90 percent relative
compaction. If the specified density is not obtained by water jetting, mechanical methods
will be required. If other types of soil or gravel are used for backfill, mechanical
compaction methods will be required to obtain a relative compaction of at least 90 percent
of maximum dry density. Backfill directly behind retaining walls should not be compacted
EnGEN Corporation
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Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 12
by wheel, track or other rolling by heavy construction equipment unless the wall is
designed for the surcharge loading. If gravel, clean sand or other imported backfill is used
behind retaining walls, the upper 18-inches of backfill in unpaved areas should consist of
typical on-site material compacted to a minimum of 90 percent relative compaction in order
to prevent the influx of surface runoff into the granular backfill and into the subdrain
system. Maximum dry density and optimum moisture content for backfill materials should
be determined in accordance with ASTM 01557-02 procedures.
8.0 MISCELLANEOUS RECOMMENDATIONS
8.1 Utilitv Trench I Recommendations: Utility trenches within the zone of influence of
foundations or under building floor slabs, hardscape, and/or pavement areas should be
backfilled with, properly compacted soil. It is recommended that all utility trenches
excavated to depths of 5.0-feet or deeper be cut back to an inclination not steeper than
1:1 (horizontal to vertical) or be adequately shored during construction. Where interior or
exterior utility trenches are proposed parallel and/or perpendicular to any building footing,
the bottom of the trench should not be located below a 1: 1 plane projected downward from
the outside bottom edge of the adjacent footing unless the utility lines are designed for the
footing surcharge loads. Backfill material should be placed in a lift thickness appropriate
for the type of backfill material and compaction equipment used. Backfill material should
be compacted to a minimum of 90 percent relative compaction by mechanical means.
Jetting of the backfill material will not be considered a satisfactory method for compaction.
Maximum dry density and optimum moisture content for backfill material should be
determined according to ASTM 01557-02 procedures.
8.2 Finish lot Drainaae Recommendations: Finish lot surface gradients in unpaved areas
should be provided next to tops of slopes and buildings to direct surface water away from
foundations and slabs and from flowing over the tops of slopes. The surface water should
be directed toward suitable drainage facilities. Ponding of surface water should not be
allowed next to structures or on pavements. In unpaved areas, a minimum positive
gradient of 4.0, percent away from the structures and tops of slopes for a minimum
distance of 3.0-feet and a minimum of 1.0 percent pad drainage off the property in a non-
erosive manner,should be provided.
EnGEN Corporation,
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Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 13
, 8.3 Planter Recommendations: Planters around the perimeter of the structure should be
designed with proper surface slope to ensure that adequate drainage is maintained and
minimal irrigation water is allowed to percolate into the soils underlying the building.
8.4 Supplemental : Construction Observations and Testina: Any subsequent grading for
development of the subject property should be performed under engineering observation
and testing performed by EnGEN Corporation. Subsequent grading includes, but is not
limited to, any additional overexcavation of cut and/or. cut/fill transitions, fill placement, and
excavation of ,temporary and permanent cut and fill slopes. In addition, EnGEN
Corporation, should observe all foundation excavations. Observations should be made
prior to installation of concrete forms and/or reinforcing steel to verify and/or modify, if
necessary, the conclusions and recommendations in this report. Observations of
overexcavation cuts, fill placement, finish grading, utility or other trench backfill, pavement
subgrade and base course, retaining wall backfill, slab presaturation, or other earthwork
completed for the development of subject property should be performed by EnGEN
Corporation. If, any of the observations and testing to verify site geotechnical conditions
are not performed by EnGEN Corporation, liability for the safety and performance of the
development is limited to the actual portions of the project observed and/or tested by
EnGEN Corporation.
'8.5 Plan Review: Subsequent to formulation of final plans and specifications for the project
but before bids for construction are requested, grading and foundation plans for the
proposed development should be reviewed by EnGEN Corporation to verify compatibility
with site geotechnical conditions and conformance with the recommendations contained in
this report. If EnGEN Corporation is not accorded the opportunity to make the
recommended I review, we will assume no responsibility for misinterpretation of the
recommendations presented in this report.
, 8.6 Pre-Bid Conference: It is recommended that a pre-bid conference be held with the
owner or ,an authorized representative, the Project Architect, the Project Civil Engineer, the
Project Geotechnical Engineer and the proposed contractors present. This conference will
provide continuity in the bidding process and clarify questions relative to the supplemental
grading and construction requirements of the project.
EnGEN Corporation
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Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 14
8.7
Pre-Gradina Conference: Before the start of any grading, a conference should be held
with the owner or an authorized representative, the contractor, the Project Architect, the
Project Civil Engineer, and the Project Geotechnical Engineer present. The purpose of
this meeting should be to clarify questions relating to the intent of the supplemental
grading recommendations and to verify that the project specifications comply with the
recommendations of this geotechnical engineering report. Any special grading procedures
and/or difficulties proposed by the contractor can also be discussed at that time.
CLOSURE
This report has been prepared for use by the parties or project named or described in this
document. It mayor may not contain sufficient information for other parties or purposes.
In the event that changes in the assumed nature, design, or location of the proposed
structure and/or project as described in this report, are planned, the conclusions and
recommendations contained in this report will not be considered valid unless the changes
are reviewed and the conclusions and recommendations of this report are modified or
verified in writing. This study was conducted in general accordance with the applicable
standards of our profession and the accepted soil and foundation engineering principles
and practices at the time this report was prepared. No other warranty, implied or
expressed beyond the representations of this report, is made. Although every effort has
been made to obtain information regarding the geotechnical and subsurface conditions of
the site, limitations exist with respect to the knowledge of unknown regional or localized
off-site conditions that may have an impact at the site. The recommendations presented
in this report are valid as of the date of the report. However, changes in the conditions of a
property can occur with the passage of time, whether they are due to natural processes or
to the works of man on this andlor adjacent properties. If conditions are observed or
information becomes available during the design and construction process that are not
reflected in this report, EnGEN Corporation should be notified so that supplemental
evaluations can be performed and the conclusions and recommendations presented in
this report can be modified or verified in writing. Changes in applicable or appropriate
standards of care or practice occur, whether they result from legislation or the broadening
of knowledge and experience. Accordingly, the conclusions and recommendations
presented in this report may be invalidated, wholly or in part, by changes outside of the
control of EnGEN Corporation which occur in the future.
EnGEN Corporation
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Mr. Tony Boyd
Project Number: T3421-GFS
June 2006
Page 15
Thank you for the opportunity to provide our services. Often, because of design and construction
'details which occur on a project, questions arise concerning the geotechnical conditions on the
: site. If we can be of further service or should you have questions regarding this report, please do
not hesitate to contact this office at your convenience. Because of our involvement in the project
to date, we would be pleased to discuss engineering testing and observation services that may be
applicable on the project.
Distribution: (4) Addressee
Colby Matthews,
Senior Staff Geol
Expires 06-30-07
,CM/OB:sa
FILE: EnGEN\Reporting\GFS\T3421-GFS Boyd Residence, Geotechnical Feasibility Study
EnGEN Corporation
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1.
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7.
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Mr. Tony Boyd
Project Number: T3421-GFS
Appendix Page 1
TECHNICAl REFERENCES
2.
California Building Code, 2001, State of California, California Code of Regulations, Title
24, 1998, California Building Code: International Conference of Building Officials and
Califomia Building Standards Commission, 3 Volumes.
California Division of Mines and Geology, 1997, Guidelines for Evaluating and Mitigating
Seismic Hazards in California, Special Publication 117.
Hart, Earl W., and Bryant, William A., 1997, Revised 1999, Fault-Rupture Hazard Zones in
Califomia, Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zone
Maps: State of Califomia, Department of Conservation, Division of Mines and Geology, 38
Pages reviewed at the California Geological Survey's web page: http://www.consrv.ca.gov
/cgs/rghm/ap/ Mapjndex/F4E.htm#SW.
Kennedy, M.P., 1977, Recency and Character of Faulting Along the Elsinore Fault Zone in
Southern Riverside County, California: California Division of Mines and Geology, Special
Report 131, 12 p., 1 plate, scale 1 :24,000. '
Morton, D. M., 1999, Preliminary Digital Geologic Map of the Santa Ana 30' x 60'
Quadrangle, Southern California, version 1.0, Open File Report 99-172.
Riverside, County of, 2000, Transportation and Land Management Agency, Technical
Guidelines for Review of Geotechnical and Geologic Reports, 2000 Edition.
Riverside, County of, 1978, Seismic Safety/Safety Element Policy Report, June 1978, by
Envicom.
Riverside County Planning Department, January 1983, Riverside County Comprehensive
General Plan - County Seismic Hazards Map, Scale 1 Inch = 2 Miles.
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 1999. '
Southern California Earthquake Data Center (SCEDC), 2004, Southern California
Earthquake Data Center Website, http://www.scecdc.scec.org.
Tan, S.S., and Kennedy, M.P., 2000, Geologic Map of the Temecula 7.5' Quadrangle, San
Diego and Riverside Counties, California: A Digital Base Map, Version 1.0: California
Division of Mines and Geology and United States Geological Survey, Southern California
Aerial Mapping Project.
Uniform Building Code (UBC), 1997 Edition, by International Conference of Building
Officials, 3 Volumes.
3.
6.
8.
9.
10.
11.
12.
EnGEN Corporation
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LABORATORY TEST RESULTS
Mr. Tony Boyd
Project Number: T3421-GFS
Appendix Page 2
EnGEN Corporation
ZP
. Location: CALLE TORCIDA
COMPACTION TEST REPORT
ENVIRONMENTAL AND GEOTECHNICAL
ENGINEERING NETWORK CORPORATION
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COMPACTION TEST REPORT
t;
0-
~
'0
c:
Q)
"0
c:-
o
\
1\
\
\
... \
V \. 1\
/ ,\
1\
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1\
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\
129
127
125
123
121
119
4
1
ZAVfor j
Sp.G. =
2.56
16
6
8
10
Water content, %
12
14
Test specification: ASTM D 1557-02 Method A Modified
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Elevl
Depth
Classification
uses AASHTO
Nat.
Moist.
%>
No.4
%<
No.200
Sp.G.
LL
PI
SM
1.9
TEST RESULTS
Maximum dry density = 126.3 pef
Optimum moisture =9.7 %
Project No. T3421-GFS Client: TONYBOYD
Project: BOYD RESIDENCE
MATERIAL DESCRIPTION
SILTY SAND, BROWN
Remarks:
SAMPLE A
NORlH SIDE OF SITE
COLLECTED BY CM
COLLECTED ON (9/1/05)
Figure
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UBC laboratory Expansion Test Results
Job Number: T3421-GFS
Job Name: BOYD RESIDENCE
locat.ion: CALLE TORCIDA
Sample Source: NORTH SIDE OF SITE (A)
Sampled by: CM (9/1/05)
lab Technician: JH
Sample Oescr: SILTY SAND, BROWN
9/2/2005
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Wet Compacted WI.: 588.7
Ring WI.: 200.5
Net Wet WI.: 388.2
Wet Density: 117.2
Wet Soil: 225.9
Dry Soil: 207.8
Initial Moisture (%): 8:7%
Initial Dry Density: 107.8
% Saturation: 41.8%
Final WI. & Ring WI.: 616.8
Net Final WI.: 416.3
Dry WI.: 357.1
Loss: 59.2
Net Dry WI.: 354.4
Final Density: 107.0
Saturated Moisture: 16.7%
Reading 1: 0.100 N/A 1:00
Reading 2: 0.110 0.010 1:15
Reading 3: 0.112 0.012 1:30
Reading 4: 0.115 0.015 1-Sep
Dial
Change Time
Expansion Index:
15
Adjusted Index:
(UBC 18-2)
11.3
EnGEN Corporation
41607 Enterprise Circle North
Temecula, CA 92590
(951) 296-2230
Fax: (951) 296-2237
1ft--
I
3000
I
I it 2000
-
I &';n
via.
"vi
I!!..
U5~
I Q)OO
m~ 1000
.E Q)
..a.
::J Peak Ultimate
I C, pst 414 238
~.deg 38 37
0 Tan) 0.77 0.75
I 0 1000 2000 3000 4000 5000 6000
Normal Stress. pst
I 3000 Sample No. 1 2 3
Water Content, % 10.3 10.3 10.3
I 2500 3 Dry Density, pct 113.5 113.5 113.5
(ij Saturation, % 64.7 64.7 64.7
""
2000 :E Void Ratio 0.4076 0.4076 0.4076
-
I ..
a. Diameter, in. 2.42 2.42 2.42
vi 2
.. Hei ht. in. 1.00 1.00 1.00
I!!
ii5 1500 Water Content, % N/A N/A N/A
I ~
OJ Dry Density. pct
Q) U)
J::
oo 1000 Q) Saturation, %
f-
I <( Void Ratio
Diameter, in.
500 Hei ht in.
I Normal Stress, pst 1000 2000 3000
0 Peak Stress, pst 1125 2083 2670
0 0.1 0.2 0.3 0.4 Displacement. in. 0.Q7 0.11 0.11
Horiz. Displ., in. Ultimate Stress. pst 968 1770 2465
I Displacement, in. 0.25 0.23 0.25
Strain rate, in.!min. 0.20 0.20 0.20
I Sample Type: REMOLDED Client: TONY BOYD
Description: SILTY SAND, BROWN
Project: BOYD RESIDENCE
I Specific Gravity= 2.56 Source of Sample: SHEAR
Remarks: NORTH SIDE OF SITE Sample Number: A
I COLLECTED BY CM Proj. No.: T3421-GFS Date: 9/2/05
COLLECTED ON (9/1105) DIRECT SHEAR TEST REPORT
I ENVIRONMENTAL AND GEOTECHNICAL Z21
Figure ENGINEERING NETWORK CORPORATION
I Tested By: JH Checked By: JH
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Established 1906
Client Name: Engen, Inc.
Contact: Engen, Inc.
Address: 41607 Enterprise Circle N.
Temecula, CA 92590-5614
Report Date: 12-Sep-2005
Lab Sample # Client Sample ID
Matrix
A510149-01
Project#
T3421-GFS /
Sample# A Boyd
Residence
Soil
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NELAP#02101CA ELAP#1156
6100 Ouail Valley Court Riverside, CA 92507-0704
P.O. Box 432 Fliverside, CA 92502-0432
PH (951) 653-3351 FAX (951) 653-1662
www.babcocklabS.com
Analytical Report: Page 1 of 3
Project Name: Engen - Sulfate
Project Number: Purchase Order #2799
Work Order Number: A510149
Received on Ice (Y IN): No
Temp:
oc
Sample Identification
Date Sampled fu
Date Submitted fu
09/01/0500:00
09/02/05 10:20 GSO
\~ ACCO~
,,-<> {)4
,A... 4'"
",'" <"
'" '"
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NELAP #02101CA ELAP#1156
6100 Quail Valley Court Riverside, CA 92507-0704
P.O. Box 432 Riverside. CA 92502-0432
PH (951) 653-3351 FAX (951) 653-1662
www.babcocklabs.com
Client Name: Engen, Inc.
Contact: Engen, Inc.
Address: 41607 Enterprise Circle N.
Temecula, CA 92590-5614
Report Date: 12-Sep-2005
Analytical Report: Page 2 of 3
Project Name: Engen - Sulfate
Project Number: Purchase Order #2799
Work Order Number: A510149
Received on Ice (Y IN): No
Temp:
oc
Laboratorv Reference Number
A510149-01
Sample'Description
Projecl# T3421-GFS / Sample# A
Boyd Residence
Matrix
Soil
Sampled DatefTime
09/01/05 00:00
Received DatefTime
09/02/05 10:20
Analyte(s)
Result RDl
Units
Method Analysis Date Analyst Flag
Water Extract
Sulfate
NO
10
Ion Chroma!.
09/08/05 11:41 KOSN-SAG,
N_WEX
ppm
,,,, AC cOif
,,-" {)4
,"'" 4-<:'1
,:; <"
'" Z
<.>
<.> ~
~ z
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NELAP #02101CA ELAP#1156
6100 Quail Valley Court Riverside, CA 92507-0704
P.O. Box 432 Riverside, CA 92502-0432
PH (951) 653-3351 FAX (951) 653-1662
www.babcockJabs.com
~~
'.L], '
.,.".... ........,:......'...<...;-'i......<
'ii:_ ._."..'...;~;.",.;:>...;:.,.:,,;,.;.":_..,..:,;,
~."',_, ........ :"""'-"W"Cc..".~#_..:~:"
.." }:~, >_' "__ _', "':,;'f'~ ~y~"""-'~'~"~ ,.".~_.
~tr.iB'''&ESMs~~~2.CK
Established 1906
Client Name: Engen, Inc.
Contact: Engen, Inc.
Address: 41607 Enterprise Circle N.
Temecula, CA 92590-5614
Report Date: 12-Sep-2005
Analytical Report: Page 3 of 3
Project Name: Engen - Sulfate
Project Number: Purchase Order #2799
Work Order Number: A510149
Received on Ice (Y IN): No
Temp:
oc
Notes and Definitions
N_WEX Analyte determined on a 1:10 water extract from the sample.
N-SAG
ND
NR
Results reported in ppm are expressed on an air dried soil basis.
Analyte NOT DETECTED at or above the reporting limit (RDL)
Not Reported
RDL = Reportable Detection Limit
MOL = Method Detection Limit
Approval
Enclosed are the analytical results for the submitted sample(s). Babcock Laboratories certify the data presented as part of
this report meet the minimum quality standards in the referenced analytical methods. Any exceptions have been noted.
Babcock Laboratories and its officers and employees assume no responsibility and make no warranty, express or implied,
for uses or interpretations made by any recipients, intended or unintended, of this report.
(2g
t-tllJ/f73d&v{
James K. Babcock 0
President
Allison Mackenzie
General Manager
o Lawrence J. Chrystal
Laboratory Director
'cc:
Short ESB Report
1ft.
~" \" ACCORo4
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