HomeMy WebLinkAbout3629-SF; Carlsbad Crest Corporate Centre, Airport Centre; Carlsbad Crest Corporate Centre, Airport Centre Un 2; 1997-09-02" FOR
CAC ASSOCIATES
3920 WILLOW CREEK ROAD, SUITE 400
SAN DIEGO, CALIFORNIA, 92131
IN COOPERATION WITH
SMITH CONSULTING ARCHITECTS, INC.
5355 MIRA SORRENTO PLACE, SUITE 650
SAN DIEGO, CALIFORNIA, 92121
SOIL AND FOUNDATION INVESTIGATION
PROPOSED
CARLSBAD CREST CORPORATE CENTER
CARLSBAD AIRPORT CENTRE
UNIT 2, LOT 41
CITY OF CARLSBAD
SAN DIEGO COUNTY, CALIFORNIA
PROJECT NO. 3629-SF
SEPTEMBER 2, 1997
Medall, Aragon, Higley, Geotechnical, Inc.
Consultants In The Earth Sciences
__ CALIFORNIA,* NEVADA
technical,September2, 1997
Project No. 3629-SF
CAC Associates
3920 Willow Creek Road, Suite 400
San Diego, CA92131
Attention: Mr. Larry Woodward
Subject: Soil and Foundation Investigation, Proposed Carlsbad Crest Corporate
Center, Lot No. 41 of Unit 2, Carlsbad Airport Centre, City of Carlsbad, San
Diego County, California.
Gentlemen:
In accordance with your request and authorization, this report presents the findings and
conclusions of a Soil and Foundation Investigation conducted by Medall, Aragon, Higley,
Geotechnical, Inc. for the above-referenced project. Characterization of site earth
materials by field reconnaissance, subsurface exploration, and laboratory testing of
recovered soil samples was performed in order to define site suitability for the proposed
development and provide preliminary engineering design values for foundations, slabs-on-
grade, and retaining walls.
Available conceptual site development plans indicate the proposed corporate center will
consist of two, side-by-side two-story buildings on a single pad, each with a footprint area
slightly greater than 26,000 square feet. Subsurface utilities, paved parking lots, and
landscaped areas are also proposed. Structural loads not to exceed 85 kips for columns
and 3 kips per linear foot for walls are anticipated for the proposed concrete tilt-up
buildings. Finish grading of the existing sloped, sheet-graded pad will require placement
of 7 to 8 feet of fill near the southwest corner of the building pad, and a cut of
approximately 3 feet in the northeast corner.
Lot No. 41 was graded in two phases between November, 1985 and March, 1990, as a
part of mass grading for the overall Unit 2 development. Engineering observation and
testing during the first phase were performed by the firm Moore and Taber of Anaheim,
California, and during the second phase by San Diego Geotechnical Consultants, Inc.
Final grading reports indicate Lot No. 41 was developed as a fill lot over an existing south-
facing slope. The underlying bedrock reportedly consisted of sedimentary sandstones and
siltstones.
Orange County: 4500 Campus Dr., Suite 488 • Newport Beach, CA 92660 • Telephone (714) 660-9292 • Fax (714) 660-9295
Riverside County: 16801 Van Buren Blvd., Suite A • Riverside, CA 92504 • Telephone/Fax (909) 776-0345
San Bernardino County: P.O. Box 1056 • Lake Arrowhead, CA 92352 • Telephone/Fax (909) 337-5636
San Diego County: 11580 Turner Heights Dr. • Escondido, CA 92026 • Telephone/Fax (760) 749-2233
Nevada: 7400 Lakeside Dr. • Reno, NV 89511 • Telephone (702) 852-5393
CAC Associates - Lot 41
Project No. 3629-SF
September 2, 1997
Page No. 2
Two borings were placed for this study within the conceptual outlines of the proposed
buildings. Fill soils were encountered to a depth of 76 feet near the southeast corner of
Building 1. About 24.5 feet of fill was penetrated near the northeast corner of Buildjng 2.
The total differential fill thicknesses underlying the two structures is estimated to be 40 feet
for Building 1 and 31 feet for Building 2.
The fill appears to consist predominantly of silty sand, with horizontal and vertical variation
that includes localized clayey sand, sandy clay, and clayey silt. Fine-grained soils appear
to be much more prevalent in the northern third of the existing sloped pad. Moisture -
density tests on recovered samples indicated that relative compaction of the on-site fill
materials is generally greater than the accepted minimum of 90 percent of the maximum
dry density. Moisture contents appear to have increased substantially over time.
Based on the results of the field investigation, laboratory testing, and professional
experience, it is our opinion that the site generally appears to be suitable for the proposed
new construction, provided mitigation or accommodation of potential differential
settlements is incorporated into building designs. In addition to design settlement values,
this report includes preliminary recommendations for site regrading and inspection,
foundation design, slabs-on-grade, and retaining walls.
Thank you very much for this opportunity to be of service. Please do not hesitate to call
if you should have any questions.
Very truly yours,
Luis Fernafido Aragon, P.E.
Geotechnical Engineer, GE No 99
Mark G. Doerschlag
Engineering Geologist, CE
•£*4»
G/No.1752
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 3
INTRODUCTION
JThis report presents .the_results of a Soil and Foundation Investigation performed forLot
No. 41 of the Carlsbad Airport Centre (Unit 2), a large master-planned business
development in the City of Carlsbad, California. Lot No. 41 has a net site area of 4.35
acres, comprising both a sheet-graded building pad and adjacent manufactured fill slopes.
The site is located at the northeast corner of the intersection of Palomar Oaks Way and
Camino Vida Roble, as illustrated on Figure No. 1 on the following page.
The purpose of our study was to evaluate the nature of the subsurface materials underlying
the site and to provide: (1) A general opinion of site suitability for the proposed project, and
(2) Recommendations applicable to site earthwork and design of foundations, slabs-on-
grade, and retaining walls. Accordingly, the scope of our services included a surficial
reconnaissance of the site and surrounding area, subsurface exploration, recovery of
representative soil samples, laboratory testing, and geotechnical analyses. In addition, a
cursory evaluation was conducted of engineering geologic constraints posed by faulting
and seismicity. Available final grading and subsequent geotechnical site evaluation reports
for Unit 2 and Lot No. 41 were also reviewed for relevant findings. However, environmental
research for purposes of establishing whether toxic or hazardous substances had been
generated, used, stored, or disposed of on-site, or chemical testing of air, soil, or
groundwater at the site were beyond the scope of this study.
BACKGROUND INFORMATION
The current configuration of the Unit 2 portion of the Carlsbad Airport Centre includes 23
business or commercial lots, with associated paved streets and greenbelt areas. Many of
the sheet-grade SITE LOCATION Map Goes here d lots have already been developed into
office space and light manufacturing facilities. Priorto grading, the area consisted of gently
to moderately sloping natural terrain mostly underlain by soft sedimentary rocks, with
localized areas found to be underlain by relatively hard volcanic rock.
Medall, Aragon, Higiey, Geotechnical, Inc.
SITE LOCATION MAP
^L-^Sjsssft^\° */s „!« c\5
" "T; ^osmy *i : ,\;/ CT ^! CARLSB/
North
Project Name: CAC Associates - Lot 41 Project No. 3629 -SF
Medall, Aragon, Higley, Geotechnicai, Inc.Figure No. 1
CAC Associates - Lot 41 September 2,1997
Project No. 3629-SF Page No. 5
Earthwork on Unit 2 and the included Lot No. 41 apparently occurred in two phases. An
injt[al phase began in Noyember,_1985 and concluded in November,, 1986, concurrent with
mass grading of Unit 1. Grading was performed under the engineering observation and
testing of the Anaheim-based firm Moore and Taber. A Report of Geotechnical Services
was issued by Moore and Taber on February 25,1987, documenting the observations, as-
built geologic conditions, and test results for Unit 1 and the incomplete portions of Unit 2
(Job No. 285-256).
The second phase of grading to complete the Unit 2 lots was performed between August,
1989 and March, 1990. Reportedly, site observation and testing services were provided
by San Diego Geotechnical Consultants, Inc. (later a part of the firm ICG, Inc.).
In 1991, the subsurface conditions within the overall Unit 2 area were evaluated by the firm
GeoSoils Inc. (GSI), and their findings and recommendations presented in a Geotechnical
Site Evaluation report dated March 21,1991 (Work Order No. 1260-SD). Four years later,
GSI updated the previous report with a site-specific investigation of Lot No. 41. The latter
report indicates that three 24-inch-diameter bucket auger borings were drilled to
supplement the four shallow trenches excavated in 1991 on the site. Both the 1991 report
and the Update Geotechnical Report, dated January 12, 1995, were reviewed for
indications of changes to the site with the passage of time.
Grading plans supplied by the project Civil Engineer indicate Lot No. 41 was formerly a
south-facing descending slope that terminated at the floor of a small canyon near the
present-day alignment of Camino Vida Roble. Grading of Lot No. 41 required a maximum
fill of about 70 feet, measured from original ground surface elevations. The greatest fill
depths are roughly coincident with the southern side of the existing sheet-graded building
pad. The fill thins rapidly to the north and northeast to an originally proposed daylight line
near the northern lot line. The fill materials appear to have originated from both on- and
off-site areas underlain by sedimentary sandstones and siltstones.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot41 September 2, 1997
Project No. 3629-SF Page No. 6
PROPOSED CONSTRUCTION
An undated Preliminary Site Plan prepared by the firm Smith Consulting Architects Inc. was
^referenced throughout ourjnvestigation. The plan illustrates twin, two-story buildings, each
with a footprint covering slightly greater than 26,000 square feet. Associated parking lots
and landscaped areas will complete the site. The proposed structures will be served by
underground utilities. The plan indicates a finish floor elevation of 230.5 feet above sea
level and a pad elevation of 229.75 feet. Based on existing grades, it is calculated that the
sheet-graded pad will require additional maximum cuts and fills of approximately 3 feet and
8 feet, respectively. Soils for regrading of the pad will also originate from driveway cuts at
the northwest and southeast portions of the property.
Preliminary information indicates the structures will consist of concrete tilt-up construction
typical of business park development. According to the project Structural Engineer, column
loads are not anticipated to exceed 85 kips, and wall loads are not expected to exceed 3
kips per linear foot.
FIELD INVESTIGATION AND LABORATORY TESTING
Subsurface site exploration was conducted on August 8, 1997 by means of 2 borings
located within the planned building footprints. The borehole locations were selected to
identify the approximate maximum and minimum fill depths beneath the structures for
subsequent settlement analyses. The borings were advanced with a truck-mounted CME
75 drill rig equipped with 8-inch-diameter hollow-stem augers. Both borings were bottomed
within undisturbed sedimentary bedrock, at a total depth of 81.0 feet for the deeper hole
and 26.5 feet for the shallow hole. Continuous logs of the subsurface conditions
encountered in the borings were recorded by an engineering geologist representing this
firm, and the results are presented on the Boring Logs in the Appendix. The approximate
locations of the subsurface explorations are illustrated on Figure No. 2 in the Appendix.
Relatively undisturbed ring-lined barrel samples were collected from specified depths in
each of the exploratory borings. Pertinent in-situ engineering soil properties were judged
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 7
from machine behavior and penetration resistance of the barrel sampler. Disturbed bag
samples representative of the near-surface structural fill soils were also collected.
Both the discrete samples and drill cuttings were visually/manually classified in the field
according to the Unified Soil Classification System, and observations made of relative
porosity, presence or absence of organic matter, and any indication of groundwater.
Laboratory tests to determine field dry density, field moisture content, maximum dry
density, shear strength values, and compressibility characteristics were performed on the
recovered samples. Test procedures and results are presented in the Appendix.
SITE GEOTECHNICAL CONDITIONS
Surface Conditions
The sheet-graded building pad area of Lot No. 41 slopes southwestward at a 2.5% gradient
toward a rough-graded catch basin and storm drain. The pad is bounded to the west and
south by 2:1 fill slopes that descend as much as 25 feet toward Palomar Oaks Way and
Camino Vida Roble. These slopes are attractively landscaped and in excellent condition.
To the east is an ascending landscaped fill slope 25 feet high that rises to the property line
with adjacent Lot No. 40. The northern side of the pad is bounded by undeveloped
property contained within the limits of Palomar Airport, as well as a portion of recently
regraded Lot No. 42.
Despite having been vacant for over 7 years, the pad shows no evidence of significant
erosion. Native and introduced vegetation, however, has established itself on the site,
with scattered clumps of buckwheat and widespread herbaceous annuals and pampas
grass. The site appears to have been partially cleared of vegetation with a blade or
skiploader, rather than a disc.
The soil surface exhibits fine networks of polygonal shrinkage cracks. None of the cracks
was wider than about 1/4-inch, and most were much smaller. Rodent burrows are locally
very common, especially near the margins of the graded pad.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2,1997
Project No. 3629-SF Page No. 8
Subsurface Conditions
_ Soil and Bedrock
Boring B -1, the deeper of the two borings drilled for this study, encountered 76.0 feet of
compacted fill overlying sedimentary bedrock. Based on original ground surface
elevations, the boring demonstrates that approximately 10 to 11 feet of alluvium and
weathered bedrock were removed from this location prior to the start of fill placement. The
fill-bedrock contact was knife-sharp, clean, and approximately horizontal. The majority of
the fill in Boring B -1 was classified as fine to medium grained silty sand, with a somewhat
variable fines content. Clayey sand and sandy clay occasionally form thin to thick layers.
The fill soils are predominantly dense to very dense in consistency, slightly moist near the
pad surface but becoming moist at very shallow depths, and non-porous. Small amounts
of organic debris, primarily wood fragments, were observed in recovered soil samples from
scattered intervals below 35 feet in depth.
Boring B - 2 encountered fill that on average was much more heterogeneous and higher
in fines content than that in Boring B - 1. Approximately 24.5 feet of compacted fill
comprising silty sand, clayey silt, silty clay, and sandy clay lies atop an abrupt contact with
the underlying sedimentary bedrock. The calculated thickness of native soils and rock
removed by benching appears to be about 8.5 feet at the boring location. Drilling behavior
and blow counts indicated the fill has lower penetration resistance than in Boring B -1, with
most soils classified as medium dense to dense or stiff. Traces of organic debris were
commonly observed.
Sedimentary bedrock in the area is assigned to the Eocene-age Santiago Formation.
Underlying Lot No. 41, this formation consists of pale yellow to greenish gray sandy
siltstone and very silty fine-grained sandstone. Limited exposures visible in vertical cuts
on adjacent Lot No. 42 showed the formation is thinly to thickly bedded, mostly soft but
locally cemented and hard, and very closely fractured. A shallow southwesterly regional
dip is reported for the general area.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2,1997
Project No. 3629-SF Page No. 9
Laboratory Test Results _....._
Dry densities calculated from recovered samples of the compacted fill ranged from
approximately 96 to 118 pounds per cubic foot. The measured values, when correlated
to the logged soil classifications and maximum density values reported during grading,
generally meet or exceed a relative compaction of 90 percent of the laboratory maximum
dry densities. Notable exceptions occur for samples recovered from the upper 3 feet,
where the relative compaction appears to be well below the desired minimum value of 90
percent.
Field moisture contents in the fill ranged from about 11.5 to 26.6 percent of dry density.
The optimum moisture content for compaction of the near-surface soils expected to provide
building and slab support is about 13 percent. In general, moisture contents have risen in
the fill since the completion of fill placement.
Maximum Density-Optimum Moisture Content determinations were performed on
representative bulk samples to determine the compaction characteristics of the local soils.
The results of these tests are presented in the appendix.
Shear tests performed on samples considered representative of the local materials
indicated that the local soils have moderately high friction angles and relatively high
cohesions. Bearing capacity recommendations based on these test results are presented
under Foundations.
Consolidation test results performed on samples considered representative of the local
materials indicated that the local soil tested have low to moderate consolidation
characteristics. The results of the consolidation tests, which are presented graphically in
the appendix, were used to calculate expected settlements.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 10
The expansion index of representative upper soils tested was 32 which corresponds to a
low expansive potential. Since additional grading will be performed, new expansion index
Jesting_yvi[l_need_to_be performed du/ing grading, .. „ _. . _ ...."......
The Atterberg limits of the upper local soils were determined to assist in the classification
of the materials encountered. The results of these tests are presented in the appendix.
Groundwater
Groundwater was encountered as a zone of slight seepage near a depth of 55 feet in
Boring B -1. In 1995, GSI reported additional zones of seepage at depths of about 38 and
55 feet in their bucket auger exploration B - 3, located a few feet away. Indications are that
minor perched groundwater may exist in thin zones comprising relatively permeable sandy
soils. The observed seepages are not anticipated to adversely affect planned site
development. Depths to permanent groundwater are probably greater than 90 feet, based
on local topographic considerations.
FAULTING AND REGIONAL SEISMICITY
Neither active nor potentially active faults have been identified on or near the Lot No. 41
site. Evidence of faulting also was not seen in the borings or in nearby cuts excavated for
a neighboring lot. Accordingly, the potential for direct fault rupture on the site appears to
be nil.
Moderate to strong ground shaking at the site would be an expected response to rupture
of one of the many active faults in southwestern California. Potential sources of ground
shaking include, but are not limited to, the San Andreas Fault, the San Jacinto Fault, the
Elsinore Fault, and the Rose Canyon Fault: Zone. The latter fault zone is primarily an
offshore feature with poorly constrained estimates of slip rate and characteristic return
period. Holocene activity has been demonstrated for at least one on-shore portion of the
fault in the City of San Diego, and in our judgment this fault should be considered active
Medall, Aragon, Higiey, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 11
in its northerly offshore extension. However, the fault has been relatively quiescent in
.historictime.. .... ..... _ .._
GeoSoils's 1995 report presented a deterministic seismic hazard analysis indicating peak
horizontal ground accelerations at the site of 0.24g and 0.39g for maximum probable and
maximum credible events on the Rose Canyon fault system. These events would be
anticipated to have moment magnitudes of M6.0 and M7.0, respectively.
At the time of this report, the requirements for seismic design had not been established.
Unless the Structural Engineer deems more-specific data are necessary (i.e., response
spectra, site period), seismic design for this project may be performed using criteria
presented in the 1997 Uniform Building Code (UBC), Volume 2, Chapter 16, Division IV
and V, for a Soil Profile Type SD, Seismic Source Type B with a distance to the fault of
approximately 9 kilometers, and Seismic Zone 4 with a Seismic Zone Factor of 0.4.
Secondary Seismic Hazards
The items listed below represent other common seismic-related hazards evaluated on a
site-specific basis. Our analyses and judgment indicate the risk presented by these
hazards is very low to zero:
• Tsunami
• Seiche
• Mass Wasting
• Liquefaction
Dynamic settlements due to seismic shaking were estimated by GeoSoils to be on the
order of 2.25 inches. The accompanying dynamic differential settlement would be
approximately 1.25 inches, suggesting angular distortions of 1 in 550 could occur.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 12
CONCLUSIONS AND RECOMMENDATIONS
General
Based on the results of the field exploration program, laboratory testing, and professional
experience, it is our opinion that the site appears to be suitable for the proposed new
construction, provided that appropriate design allowances are made for calculated
differential settlements (static and dynamic). Additionally, remedial measures will need to
be implemented to correct loose, soft, and locally disturbed conditions of the pad soils in
the upper 2 to 3 feet. Excavation and recompaction are recommended to mitigate the
loose conditions and create satisfactory support characteristics. In the building areas, the
extent of the over-excavation work should be 1 foot below the lowest (elevation) foundation
element and a minimum of 3 feet from existing grade (whichever is greatest), if shallow
foundations are adopted. This overexcavation should extend down outside of the building
footprint at a 1:1 (horizontal to vertical) projection to the full depth of the removal.
Areas outside of the building footprints but planned for parking and hardscape should be
stripped of approximately 2 feet of surficial fill or to competent material, whichever is
greater. Additionally, the test pits excavated by GeoSoils in 1991 were backfilled without
compaction; these must be located and the loose soils properly recompacted prior to
placement of additional fill on the site. All of the on-site soils are considered to be suitable
for reuse in compacted structural fills. Specific guidelines and recommendations for site
grading, structural design, and inspections are presented in the following subsections.
Site Grading
The general guidelines presented below should be included in the project construction
specifications to provide a basis for quality control during grading. It is recommended that
all structural fills be placed and compacted under engineering observation and in
accordance with the following:
• Re-established native and introduced vegetation shall be cleared and properly
disposed of off-site.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 13
• Excavation of the existing low-density and disturbed fill shall be performed as
discussed above, in areas_which_j/vilLsupporL_foundations, slabs-Degrade,- and
pavements. Actual removal depths may vary during grading based upon conditions
encountered during earthwork activities.
• Observation and density testing by the Geotechnical Engineer of all undisturbed
cleared areas prior to processing of the exposed bottom. The minimum acceptable
relative compaction of the undisturbed materials will be 90 percent of the maximum
dry density.
• Scarification to depths of 8 to 10 inches, moisture-conditioning, and processing of fill
materials left in place by adding moisture or drying back to slightly above optimum
moisture content, mixing, and recompaction to at least 90 percent of the maximum dry
density as determined by the ASTM D 1557 test method. Bottoms shall be proof-
rolled with heavy rubber-tire equipment (earthmoving scrapers, large loaders, or
similar) to detect soft zones prior to additional fill placement.
• Placement of fill soils moisture-conditioned to approximately 2 percent over optimum
moisture in lifts having a thickness commensurate with the type of compaction
equipment used, but generally no greater than 6 to 8 inches. Rocks or other similar
irreducible matter larger than about 3 inches in diameter should be excluded from
engineered structural fills on this site. Sufficient compactive effort shall be maintained
to obtain compaction of at least 90 percent of the maximum dry density.
• Field density testing shall be performed to verify that the desired compaction is being
achieved. Where compaction of less than 90 percent is indicated, additional
compaction effort, with adjustment of the moisture content as necessary, shall be
made until at least 90 percent compaction is obtained.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 14
• Import soils, if required, should consist of predominantly granular material with low or
negligible expansive potential Jree of deleterious organic matter and large rocks,_and
shall be accepted by the Geotechnical Engineer prior to use.
• Fine grading of building pads should result in drainage being directed away from
building foundations to swales for offsite disposal. The minimum desirable slope away
from buildings is 2 percent for a distance of at least 5 feet.
• It is recommended that expansion index testing be performed during or upon
completion of the regraded building pad, to verify preliminary observations of low to
moderate expansion potential in the on-site materials. The exact number of tests
should be determined by site observations made during grading, but should not be
less than one test for each soil type encountered in the finished lot.
Removal and recompaction of the on-site soils will result in some material volume loss.
Based on observations and laboratory density tests, it is estimated that shrinkage will
average 3 to 5 percent for the existing loosened structural fill soils if replaced with an
average relative compaction of 92 percent. Subsidence of approximately 0.1 to 0.2 foot
should also be anticipated for excavated areas proof-rolled as recommended above.
FOUNDATIONS
It is our understanding that the proposed structures will consist of two, one- to two-story
commercial tilt-up buildings. Preliminary information indicates the proposed buildings will
be supported on conventional, continuous and square shallow foundations. As previously
mentioned, column loads are not expected to exceed 85 kips, while wall loads are unlikely
to exceed 3 kips per linear foot. Information and recommendations presented in this
section are not meant to supersede final design by the Structural Engineer.
Medali, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 15
Settlement
Foundation Settlement due to Structural Loads
_ For one to two stoi^ commercial buildings, _the_ anticipated JotaLsettlementis_1.2Joches.-
Approximately 50 percent of the anticipated total settlement is expected to occur during
construction. The anticipated differential settlement is 0.3 inch over 40 feet.
Primary Settlement of Fill
The proposed fill is anticipated to vary in thickness from approximately 2 to 8 feet for
Building 1, and 0 to 3 feet for Building 2. The anticipated total settlement due to the
surcharge imposed by the new fill is expected to vary from 0.75 to 3 inches for Building 1
and 0 to 1 inch for Building 2.
For Building 1 approximately 50 to 60 percent of the settlement will occur during and
shortly after fill placement and approximately 90 percent of the settlement shall be
complete in 3 to 4 months. It is our opinion that the proposed fill within Building 1 should
be monitored for settlement to ensure that the primary settlement is complete. Otherwise
an additional estimated total and differential settlement of 1.25 inch and 0.2 inch over 40
feet, respectively, should be used in the design.
For Building 2 the primary settlement due to the proposed fill should be complete during
and shortly after fill placement.
Secondary Settlement of Fill
The fill may continue to settle, due in part to secondary compression, new building loads
and continued landscape irrigation at the surface. The depth of existing fill from the
proposed pad grades varies from approximately 40 to 80 feet across the proposed Building
1 footprint, and from approximately 22 to 53 feet across the proposed Building 2 footprint.
The estimated long term total settlements for Buildings 1 and 2 are 2.0 inches and 1.0 inch,
respectively. The anticipated differential settlement for Buildings 1 and 2 are 0.25 inch
over 40 feet, respectively.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 16
Foundation Design
Bearing Value
(.1) ^An.allowable_verticaLbearing value.of.2,9.0.0 pounds per square.foot(psf) may-be-
considered for design of continuous footings at least 24 inches wide and 24 inches
deep, and for design of square footings at least 24 inches wide and 24 inches deep,
bearing in properly compacted fill material tested by our personal during the upcoming
additional site grading. The bearing value may be increased by 300 psf for each
additional foot in depth to a maximum of 3,500 psf. The above value may be
increased by one-third when considering short duration seismic or wind loads.
Exterior square footings should be tied with a grade beam or tie beam to the main
foundation.
(2) All footings should be embedded a minimum of 24 inches into properly compacted
fill.
(3) All continuous footings should be minimally reinforced with four No. 5 steel bars, two
near the top and two near the bottom.
(4) Interior columns should be supported on spread footings or integrated footing and
grade beam systems. Column loads should not be supported directly by slabs.
When designing the interior building footings, the Structural Engineer should consider
utilizing grade beams to control lateral drift of isolated column footings, if the
combination of friction and passive earth pressure will not be sufficient to resist lateral
forces.
Lateral Pressure
(1) Passive earth pressure of compacted fill may be computed as an equivalent fluid
having a density of 250 pcf per foot of depth, to a maximum earth pressure of 2,000
psf.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 17
(2) An allowable coefficient of friction between properly compacted fill soil and concrete
of 0.32 may.be Jjsed with the.deadjoad forces.
(3) When combining passive pressure and frictional resistance, the passive pressure
component should be reduced by one-third.
(4) All footings should maintain a minimum seven foot horizontal setback from the base
of the footing to any descending slope. This distance is measured from the footing
face at the bearing elevation.
(5) The upper six inches of passive pressure should be neglected if not confined by slabs
or pavement.
Foundation Construction
All footings should be embedded a minimum of 24 inches into properly compacted fill.
Foundation footings should be minimally reinforced with four No. 5 bars, two near the top
and two near the bottom (in the cross-sections). Foundations should either be continuous
footings across large openings (i.e., garages or entrances) or be tied with a grade beam
or tie beams. All exterior isolated footings should be tied in at least two perpendicular
directions by grade beams or tie beams to reduce the potential for lateral drift or differential
distortion. The base of the grade beams should enter the adjoining footings at the same
depth as the footings (i.e., in profile view). The grade beam steel should be continuous at
the footing connection. Grade beams and footings should be minimally reinforced and
sized per the Structural Engineer's recommendations.
Prior to placing steel or concrete, the footing and grade beam excavations should be well
moistened.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2,1997
Project No. 3629-SF Page No. 18
FLOOR SLABS
Floor Slab Design
_Concrete.slab-onTgrade floor-construction is anticipated.^The.following recommendations-
are presented as minimum design parameters for the slab. Design parameters do not
account for concentrated loads (e.g., forklifts, other machinery, etc.) and/or the use of
freezers or heating boxes.
The information and recommendations presented in these sections are not meant to
supersede design by the project Structural Engineer.
Lightly Loaded Floor Slabs
The slabs in areas which will receive relatively light live loads (i.e., less than 50 psf) should
be a minimum of five inches thick and be reinforced with No. 3 reinforcing baron 18 inches
centers in two horizontally perpendicular directions. Reinforcing should be properly
supported to ensure placement near the vertical midpoint of the slab. "Hooking" of the
reinforcement is not considered an acceptable method of positioning the steel. The
recommended compressive strength of concrete is 3,000 pounds per square inch (psi).
The project Structural Engineer should consider the use of transverse and longitudinal
control joints to help control slab cracking due to concrete shrinkage or expansion.
Transverse and longitudinal crack control joints should be spaced no more than 12 feet on
center and constructed to a minimum depth of T/4, where "T" equals the slab thickness in
inches.
Highly Loaded Floor Slabs
The project structural engineer should design the slabs in areas subject to high loads (ie.,
machinery, forklifts, storage racks, etc.). The modulus of subgrade reaction (k-value) may
be used in the design of the floor slab supporting heavy truck traffic, fork lifts, machine
foundations and heavy storage areas. A k-value (modulus of subgrade reaction) of
Medal I, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 19
100 pounds per square inch per inch (pci) would be prudent to utilize for preliminary slab
design. An R-value test and/or plate load test may be used to verify the modulus of
subgrade on near _surface fiJLspils, ._
The following recommendations are meant as minimums. The project Structural Engineer
should review and verify that the minimum recommendations presented herein are
considered adequate with respect to anticipated uses.
Concrete slabs should be at least 5Yz inches thick and reinforced with at least #3
reinforcing bars placed 18 inches on center in two directions. Concrete slabs should be
underlain with a minimum of four inches of % inch crushed rock (vibrated into place) or
four inches of aggregate base materials (class 2 aggregate base or equivalent) compacted
to a minimum relative compaction of 95 percent. Transverse and longitudinal crack control
joints should be spaced no more than 12 feet on center and constructed to a minimum
depth of T/4, where "T" equals the slab thickness in inches. The recommended
compressive strength of concrete is 4,000 pounds per square inch (psi).
Subgrade Preparation
The subgrade material should be compacted to a minimum 90 percent of the maximum
laboratory dry density. Prior to placement of concrete, the subgrade soils should be
moisture conditioned to at least optimum moisture content, to a depth of 12 inches and
verified by a field representative of this office.
Moisture Protection
In areas where moisture condensation is undesirable (e.g., areas to have moisture
sensitive floor coverings) a minimum 10 mil plastic membrane should be placed with all
laps/openings sealed. The membrane should be sandwiched between two, two inch
(minimum) sand layers. These areas should be separate from areas not similarly
protected. This separation could be provided with a concrete cut-off wall extending at least
18 inches into the subgrade soil below the sand layer.
Medal!, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 4.1 September 2, 1997
Project No. 3629-SF Page No. 20
RETAINING WALLS
General
Equivalent fluid pressure parameters are presented herein for either the use of native or
low expansive select granular backfill to be utilized behind the proposed walls. The low
expansive granular backfill should be provided behind the wall at a 1:1 (h:v) projection from
the heal of the foundation system. Low expansive fill is defined as Class 3 aggregate base
rock, or Class 2 permeable rock. Wall backfilling should be performed with lightly loaded
equipment within the same 1:1 (h:v) projection (i.e., hand tampers, walk behind
compactors). If highly expansive soils are used to backfill the proposed walls, increased
active and at-rest earth pressures will need to be utilized for retaining wall design.
Foundation systems for any proposed retaining walls should be designed in accordance
with the recommendations presented in the Foundation Recommendation section of this
report. Building walls, below grade, should be water-proofed or damp-proofed, depending
on the degree of moisture protection desired. All walls should be properly designed in
accordance with the recommendations presented below.
Some movement of the walls constructed should be anticipated as soil strength
parameters are mobilized. This movement could cause some cracking depending upon
the materials used to construct the wall. To mitigate this effect, the use of vertical crack
control joints and expansion joints should be employed, spaced at 20 feet or less along the
walls. Vertical expansion control joints should be filled with a flexible grout. Wall footings
should be keyed or doweled across vertical expansion joints.
Cantilevered Walls
These recommendations are for cantilevered retaining walls up to 10 feet high. Active
earth pressure may be used for retaining wall design, provided the top of the wall is not
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41
Project No. 3629-SF
September 2,1997
Page No. 21
restrained from minor deflections. An empirical equivalent fluid pressure approach may
be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights
are provided for-specific slope gradients of the retained material (see table below). These
do not include other superimposed loading conditions such as traffic, structures, seismic
events or adverse geologic conditions. For cantilever retaining walls greater than four feet
in height, a seismic increment of 10H (uniform pressure) for level backfill and 20H for
backfill sloped at 2:1 (h:v) behind the walls should be considered. If traffic is within a
distance H behind any wall or a 1:1 (h:v) projection from the heel of the wall foundation,
a pressure of 100 psf per foot in the upper five feet should be used. Structural loads from
adjacent properties and their influence on site walls should be reviewed by the Structural
Engineer, if within a 1:1 (h:v) projection behind any site wall.
f ~* J "4 >
'< { '' ^'< ^
SURFACED SLOPE:OF
, RETAINED MATERIAL
(HORIZONTAL TO VERTICAL) ,
Level
2:1
EQUIVALENT FLUID WEIGHT*
FOR BACKFILL TYPE ; ,
.SELECT
;-r' SOIL ,(Granular)
35
45
.ONSITE
.^ :' *" SOIL'' .-' '
45
60
*To be increased by traffic structural surcharge and seismic loading as needed.
Wall Backfill and Drainage
All retaining walls should be provided with an adequate backdrain and outlet system (a
minimum of two outlets per wall) to prevent buildup of hydrostatic pressures and be
designed in accordance with the minimum standards presented herein. Drain pipe should
consist of four inch diameter perforated schedule 40 pvc pipe embedded in gravel. Gravel
used in the backdrain systems should be a minimum of three cubic feet per lineal foot of
% to rA inch clean crushed rock wrapped in filter fabric (Mirafi 140 or equivalent) and 12
inches thick behind the wall. The surface of the backfill should be sealed by pavement or
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41
Project No. 3629-SF
September 2, 1997
Page No. 22
the top 18 inches compacted to 90 percent relative compaction with native soii Proper
surface drainage should also be provided. Weeping of the wails in iieu of a backdrain is
not recommended.
A paved drainage channel (v-ditch or substitute), constructed of either concrete or asphaltic
concrete and located behind the top of the walls with sloping backfill, should be considered
to reduce the potential for surface water penetration. For level backfill, the grade shouid
be sloped such that drainage is toward a suitable outlet at one to two percent.
PAVEMENTS
Soft materials, if any, in areas to support asphalt pavement, should be recompacred to a
depth of at leasi one foot below the final subgrade just prior to placement of driveway and
parking lot base course.
Since additional grading will take place, it is not known at this time what the pavement
bearing characteristics of the final subgrade soils will be Therefore, it is recommended
that R-value testing of the subgrade soils be performed upon completion of grading in
order to provide design pavement structural sections. For preliminary design purposes.
it is assumed that the R-vaiue for typical local soils may range from 20 to 45 Preliminary
pavement structural calculations based on these assumed R-values and traffic indexes of
'4^fcr parking stalls) an<j£5_fJUfor light vehig^ access areas) Indicate that pavement
sections shouid range from
/^i^MAggregate Base Material tcQ inches of AC over 7 inchiS)of Class 2 Aggregate Base
Material In heavy traffic areas, or in areas of heavy truck traffic, the structural sections wil'
be larger. -Concrete gutters shodd-be provided at flow lines and thef aved areas should
be graded so as to permit rapid and unimpaired flow of runoff water The final street
pavement design shouid be based on the actual R-value of the subgrade soils obtained
after grading. «- , -. • .- RECEIVEDy a
0
Medall, Aragdn, Higley, Geotechnical, Inc.
Masson &.
CAC Associates - Lot 41 September 2,1997
Project No. 3629-SF Page No. 22
the top 18 inches compacted to 90 percent relative compaction with native soil. Proper
surface drainage should also be provided. Weeping of the walls in lieu of a backdrain is
not recommended.
A paved drainage channel (v-ditch or substitute), constructed of either concrete or
asphaltic concrete and located behind the top of the walls with sloping backfill, should be
considered to reduce the potential for surface water penetration. For level backfill, the
grade should be sloped such that drainage is toward a suitable outlet at one to two
percent.
PAVEMENTS
Soft materials, if any, in areas to support asphalt pavement, should be recompacted to a
depth of at least one foot below the final subgrade just prior to placement of driveway and
parking lot base course.
Since additional grading will take place, it is not known at this time what the pavement
bearing characteristics of the final subgrade soils will be. Therefore, it is recommended
that R-value testing of the subgrade soils be performed upon completion of grading in
order to provide design pavement structural sections. For preliminary design purposes,
it is assumed that the R-value for typical local soils may range from 20 to 45. Preliminary
pavement structural calculations based on these assumed R-values and traffic indexes of
4.5 (for parking stalls) and 5.0 (for light vehicle access areas) indicate that pavement
sections should range from approximately 3 inches of A.C. over 4 inches of Class 2
Aggregate Base Material to 3 inches of A.C. over 7 inches of Class 2 Aggregate Base
Material. In heavy traffic areas, or in areas of heavy truck traffic, the structural sections
will be larger. Concrete gutters should be provided at flow lines and the paved areas
should be graded so as to permit rapid and unimpaired flow of runoff water. The final
street pavement design should be based on the actual R-value of the subgrade soils
obtained after grading.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2; 1997
Project No. 3629-SF Page No. 23
INSPECTION
The preliminary opinions and recommendations in this report are based on the assumption
that all footings and slab-on-grade floors will be placed on properly compacted soils
approved by this office. Site grading operations should be performed under observation
by our personnel. All footing excavations should be observed prior to placing concrete to
verify that footings are founded on satisfactory soils and that excavations are free of loose
or disturbed materials.
The findings in this report may require modification as a result of later field exploration or
observations made prior to or during site regrading. This report has also incorporated
assumed conditions/characteristics of the proposed development where specific
information was not available. Grading and foundation plan reviews should be performed
by this firm prior to site grading in order to evaluate the proposed construction from a
geotechnical viewpoint. If unforeseen adverse geologic or geotechnical conditions are
encountered during grading, then additional appropriate mitigation recommendations may
be required from this office.
CLOSURE
This report was prepared for the use of CAC Associates and their designates in
cooperation with this office. We cannot be responsible for the use of this report by others
without observation of the grading operations and footing excavations by our personnel.
The findings and recommendations of this report were prepared in accordance with
generally accepted professional engineering principles and practice in the fields of soil
mechanics, foundation engineering, and engineering geology. We make no other
warranty, either expressed or implied. Our conclusions are based on the results of the
field exploration combined with interpolations of soil conditions between a limited number
of subsurface excavations. The nature and extent of variations beyond the explorations
may not become evident until construction. If conditions are encountered during site
development that appear to be different than those indicated by this report, this office
should be notified.
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41
Project No. 3629-SF
September 2, 1997
Page No. 24
It is a pleasure to cooperate in this project. If you should have any questions, please
contact our office.
Respectfully submitted,
Medall, Aragon, Higley, Geotechnical Inc.
^
Luis Fernafrtfo Aragon, P.E.
Geotechnical Engineer, GE No. 99
Mark G. Doerschlag ~~"\
Engineering Geologist, CEG No. 1752
MGD/LFA
Distribution: (4) Addressee
Enclosure: Appendix
Medall, Aragon, Higley, Geotechnical, Inc.
APPENDIX
Medall, Aragon, Higley, Geotechnical, Inc.
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 26
APPENDIX
FIGURES AND SUBSURFACE EXPLORATION LOGS
The Subsurface Exploration Map was prepared based upon information supplied by the
client, or others, along with field measurements and observations made by members of this
firm. Boring locations illustrated on the map are approximate.
The Boring Logs on the following pages depict or describe the subsurface (soil and water)
conditions encountered at the specific exploration locations on the date that the exploration
was performed. Subsurface conditions may differ between exploration locations and within
areas of the site that were not explored. The subsurface conditions may also change at
the exploration locations over the passage of time.
The field operations were conducted in general accordance with the procedures
recommended by the American Society for Testing and Materials (ASTM) designation D
420 entitled "Standard Guide for Sampling Soil and Rock" and/or other relevant
specifications. Soil samples were preserved and transported to our laboratory in general
accordance with the procedures recommended by ASTM designation D 4220 entitled
"Standard Practice for Preserving and Transporting Soil Samples". The results of field
testing (e.g., N*-Values) are reported on the Boring Logs. Brief descriptions of the
sampling and testing procedures are presented below:
Ring-Lined Barrel Sampling - (ASTM D 3550)
In this procedure, a barrel sampler constructed to receive a stack of 1-inch-high brass rings
is used to collect soil samples for classification and laboratory testing. For this
investigation, a 140-pound hammer falling 30 inches was used to drive a barrel fitted with
2.5-inch-diameter rings. An uncorrected NT-value of the number of blows needed to drive
the sampler the final 12 inches of an 18-inch barrel was recorded. The method provides
relatively undisturbed samples that fit directly into laboratory test instruments without
additional handling/disturbance.
Bulk Sample
A relatively large volume of soil is collected with a shovel or trowel. The sample is
transported to the materials laboratory in a sealed plastic bag or bucket.
Classification of Samples
Excavated soils and discrete soil samples were visually-manually classified, based on
texture and plasticity, in general accordance with the Unified Soil Classification System
(ASTM D 2488-75). The classifications are reported on the Boring Logs.
Medal!, Aragon, Higley, Geotechnical, Inc.
SUBSURFACE EXPLORATION MAP
CAM I. _
Indicates location of exploratory boring
Project Name: CAC Associates - Lot 41 Project No. 3629 -SF
Medall, Aragon, Higley, Geotechnical, Inc.Figure No. 2
BORING LOG
Logged By: MOD Date: 8-8-97 Drill Rig:CME75, Downhole hmr.
This log is a representation of subsurface conditions at the time and place of drilling. With the
passage of time or at any other location, there may be consequential changes in conditions
SAMPLE
- 3--CQ
1
I
11
UJ
COD(-
!' N*BLOWS/FT49
65
76
58
50 FIELD MOISTURE% DRY WEIGHT126.1
20.8
18.3
15.7
12.3
H
• vi
§t
5~-4
Q
99.4
105.1
111.3
111.0
116.6 SHEAR RESISTANCEKIPS/FT2UJUJ
- i-UJQ
5
10
15
20
^
§W
j>
W
SM
Boring Diameter: 8" (Auger) BorinQ No
B -1Elevation: 224 Feet
GEOLOGICAL / ENGINEERING
DESCRIPTIONS AND REMARKS ..._.
Silty Sand: [FILL] Dense to very dense; mottled
gray, yellowish-brown, orange; moist; fine to
trace medium grained; clayey; trace of gravel;
abundant siltstone fragments.
More clayey 0-4 feet.
Mottled grayish-orange, dark gray and light
gray; much less clay; no gravel.
Some orange Fe staining; siltstone fragments to
size greater than 3"
Continues on next page
MEDALL, ARAGON, HIGLEY
GEOTECHNICAL, INC.
PROJECT NAME PROJECT No. PAGE No.
CAC Associates 3629-SF 28
BORING LOG (Continuation)
Logged By: MGD Date: 8-8-97 Drill Rig:CME75, Downhole hmr Boring Diameter: 8" (Auger) Borin
This log is a representation of subsurface conditions at the time and place of drilling. With the E| .. . __ . F B •
passage of time or at any other location, there may be consequential changes in conditions va '
SAMPLE
*:_j_ D...CD
LU
CO
— 3~h-|N*BLOWS/FT45
67
65
54 FIELD MOISTURE% DRY WEIGHT21.3
15.9
23.4
25.9 DRY DENSITYLB/FT3103.5
107.4
103.5
98.0 SHEAR RESISTANCEKIPS/FT2!IDEPTH (FEET)25
30
35
40 SOIL /ROCKTYPESM,
SC
SP-
SM
SC/
CL
g No.
-1
GEOLOGICAL / ENGINEERING
DESCRIPTIONS AND REMARKS
Silty Sand: [FILL] At 20' some clods of olive
clayey sand.
Much less silt; light gray color.
3_hrn\A/n
Becomes interlayered sandy clay and clayey
sand; mottled olive-brown, very dense or
hard, moist.
Same; with some dark brown sandy clay
containing small organic fragments.
Continues on next Page
MEDALL, ARAGON, HIGLEY
GEOTECHNICAL, INC.
PROJECT NAME PROJECT No.
CAC Associates 3629-SF
PAGE No.
29
BORING LOG (Continuation)
Logged By: MGD Date: 8-8-97 Drill Rig:CME75, Downhole hmr
This log is a representation of subsurface conditions at the time and place of drilling. With the
passage of time or at any other location, there may be consequential changes in conditions
Boring Diameter: 8" (Auger)
Elevation: 224 Feet
Boring No.
B-1
SAMPLE
LUm
Q OH
«
UJ LL
"03-
>- -Io:Q
LUoL-It-
Ico
(Joa: LLJ_ Q.GEOLOGICAL / ENGINEERING
DESCRIPTIONS AND REMARKS
55 21.3 103.5
SM,
SC
45
39 24.2 99.7 CL,
SC
50 SP-
SM
64 12.4 117.9
55
38 16.2 110.6
60
Returns to mostly Silty Sand and Clayey
Sand [FILLI]; mottled light gray, orange, olive-
gray; moist.
Becomes predominantly sandy clay; dark-
olive to purplish black color with common
small wood fragments; moist. Harder drilling
effort to 49'.
Becomes predominantly slightly silty sand;
fine-grained; pale olive gray and orange.
Same; very moist, with trace free water on
rings; trace sandstone fragments
Continues on next page
MEDALL, ARAGON, HIGLEY
GEOTECHNICAL, INC.
PROJECT NAME
CAC Associates
PROJECT No.
3629-SF
PAGE No.
30
BORING LOG (Continuation)
Logged By: MGD Date: 8-8-97 Drill Rig:CME75, Downhole hmr
This log is a representation of subsurface conditions at the time and place of drilling. With the
passage of time or at any other location, there may be consequential changes in conditions
Boring Diameter: 8" (Auger)
Elevation: 224 Feet
Boring No.
B-1
SAMPLE
LU
CD"_co
o
co
22 Hi
Q OH-J Q
E
CO „
01 u...
anQ
LUo
•K 9T
Xco
GEOLOGICAL / ENGINEERING
DESCRIPTIONS AND REMARKS
77 15.1 113.4
>50 13.9 112.4
83 16.3 103.1
SM,
SC
Silty Sand, continuation [FILL]
Some clayey sand in clods or thin layers.
65
CM,
SC
70 [No sample at 70'; rig down. Rig exchanged
for CME 75 with auto hammer & rods.
Overdrilled hammer to 75'. Cuttings very
moist Silty Sand].
Clayey Sand - [FILL] Olive brown, trace organics
and sandstone fragments. Abrupt contact at 76.0'.
75
SC
RX Siltstone: Variably pale gray, pale yellow, orange;
very sandy with fine grained sand; massive;
soft; weak; apparent close Fe-stained
fractures [Santiago Formation]
so
Continues on next page
MEDALL, ARAGON, HIGLEY
GEOTECHNICAL, INC.
PROJECT NAME
CAC Associates
PROJECT No.
3629-SF
PAGE No.
31
BORING LOG
Logged By: MOD Date: 8-8-97 Drill Rig:CME75, Downhole Boring Diameter: 8" (Auger) Rorina No
a - z
This log is a representation of subsurface conditions at the time and place of drilling. With the Elevation- 224 Feet
passage of time or at any other location, there may be consequential changes in conditions
SAMPLE
•XL' i-3CD.
„
I
111
1
- UJm
^t-N*BLOWS/FT115
37
35
46
17
30
29 iFIELD MOISTURE% DRY WEIGHT26.6
12.0
20.1
11.4
20.1
14.7 DRY:DENSITYLB/FT395.9
106.8
103.0
102.8
106.1
103.7 lSHEAR !RESISTANCE•£LUU-_
-I- .\-0.UJa
5
10
15
20 SOIL /ROCKTYPE]ML
CL
SM
ML
SM
SM,
SC
SM,
SC,
SP-
SM
GEOLOGICAL / ENGINEERING
DESCRIPTIONS AND REMARKS
Sandy Silt w/Clay: Stiff; olive brown; moist [Fill]
Silty Clay: Very stiff to hard; olive; moist; mod.
plastic.
Silty Sand: Dense; mottled olive gray, light gray,
orange; moist; tr. clay.
Clayey Silt: hard; dark olive brown; moist; trace
organic debris and abundant siltstone frags.
Silty Sand: Similar to 5-7 ft. interval - medium dense
to dense; mottled colors.
Some Clods/layers of clayey sand, brown & olive
colors, slightly plastic.
Same
Same, some slightly silty sand; local traces of
organic debris.
Continues on next page
MEDALL, ARAGON, HIGLEY
GEOTECHNICAL, INC.
PROJECT NAME PROJECT No. PAGE No.
CAC Associates 3629-SF 33
BORING LOG
Logged By: MGD Date: 8-8-97 Drill Rig:CME75, Downhole hmr.
This log is a representation of subsurface conditions at the time and place of drilling. With the
passage of time or at any other location, there may be consequential changes in conditions
SAMPLE
-LCD
UJDQ N*BLOWS/FT26
84 FIELD MOISTURE% DRY WEIGHT13.5
7.4 ]DRY DENSITYLB/FT3I101.6
118.8 SHEARRESISTANCEUJ
-if-UJQ
25
30
35
40 SOIL / ROCK[ TYPESM,
SC
CL
RX
Boring Diameter: 8" (Auger) BOFinq NO.
Elevation: 224 Feet B-2
GEOLOGICAL / ENGINEERING
DESCRIPTIONS AND REMARKS
Silty & Clayey Sand, con't [Fill]
Sandy Clay: very stiff to hard; olive; moist; slightly
plastic. Abrupt contact.
Siltstone: Very pale greenish gray; moist; sandy;
massive; soft, weak; some visible Fe stained fractures.
[Santiago Fm.]
Bottom of boring at 26.5 ft.
No groundwater encountered.
Boring backfilled with cuttings.
Original ground surface elevation at 216'.
MEDALL, ARAGON, HIGLEY
GEOTECHNICAL, INC.
PROJECT NAME
CAC Associates
PROJECT No. PAGE No.
3629-SF 34
CAC Associates - Lot 41
Project No. 3629-SF
September 2, 1997
Page No. 35
LABORATORY TESTING
Moisture-Density Determinations- -----
The dry unit weight and field moisture content were determined for each of the recovered
barrel samples. The moisture-density information provides a gross indication of soil
consistency and can assist in delineating local variations. The information can also be
used to correlate soils found on this site with soils on other sites in the general area.
The test results indicate that the dry density of the soils and weathered bedrock tested
ranges from 95.9 to 118.8 pounds per cubic foot, with moisture contents ranging from 7.4
to 26.6 percent of dry unit weight. Sample locations and the corresponding test results are
illustrated on the Boring Logs.
Compaction Tests
Representative bulk soil samples were tested to determine their maximum dry densities
and optimum moisture contents per the ASTM D 1557-91 (Method A) procedure. The test
method uses 25 blows of a 10-pound hammer falling 18 inches on each of 5 soil layers in
a 1/30 cubic foot cylinder. Soil samples are tested at varying moisture contents to create
a curve illustrating achieved dry density as a function of moisture content. The following
table presents the test results.
LOCATION
B-1 @ r-51
8-2 @ 0-4'
SOIL TYPE
Silty Sand
Sandy Silt with
Clay
MAXIMUM
DENSITY (pcf)
116.5
122.0
OPTIMUM MOISTURE
CONTENT (%)
13.5
13.0
Shear Strength Tests
Direct shear tests were performed on undisturbed samples in general accordance with
ASTM Test Method D-3080. The samples were saturated, drained of excess moisture, and
tested in a direct shear machine of the strain control type. Test samples are retained within
standard one-inch-high brass rings. Samples were tested at increasing normal loads to
determine the Mohr-Coulomb shear strength values presented graphically in the following
page.
Medall, Aragon, Higley, Geotechnical, Inc.
I—
CD
Ula:i—en
a:<JCixl
05
NORMAL PRESSURE
Bor i ng Depth
No. (feet) Test Method
B-2 6.00 UNDISTURBED
Nature
Moist.Saturated
X
Cohes i on
(psf)
600
Fric. Angle
(degree)
26
GeoSoi Is, Inc.
SHEAR TEST DIAGRAM
Date: AUG 97 U.O.: U.0.3247-OC
PLATE
B - 6
CAC Associates - Lot 41 September 2, 1997
Project No. 3629-SF Page No. 37
Consolidation Tests
Consolidation testing was performed on representative samples of existing fill materials
encountered in accordance"with ASTM Test Method D-2435. Inlhis procedure, a series
of cumulative vertical loads are applied to a small, laterally confined soil sample. The
apparatus is designed to accept a one-inch-high brass ring containing an undisturbed or
remolded soil sample. During each load increment, vertical compression (consolidation)
of the sample is measured and recorded at selected time intervals. Porous stones placed
at the top and bottom of the specimen allow ready addition or release of water.
Undisturbed samples are initially at field moisture content, and are subsequently inundated
to determine soil behavior under saturated conditions. The test result are plotted
graphically on the following pages.
Medall, Aragon, Higley, Geotechnical, Inc.
o
QH
aCO
10
12
14
16
18
20
0.1 10
NORMAL PRESSURE (ksf)
Boring No. B-l Depth (feet): 20.00 Sample:
GeoSo i 1 s, Inc,
CONSOLIDATION TEST
Date: AUG 97 U.O.: W.0.3247-OC
PLATE
B-l
oH
<tQ
OU)
Oa
10
14
16
18
200.1 10
NORMAL PRESSURE (ksf)
Boring No. 8-1 Depth (feet): 55.00 Sample: WATER @ 8 KIPS
GeoSoi Is, Inc.
CONSOLIDATION TEST
Date: AUG 97 14. 0.: 14.0.3247-OC
PLATE
B - 2
20
0.1 10
NORMAL PRESSURE (ksf)
Boring No. B-2 Depth (feet): 12.50 Sample: WATER <§ 1 KIP
GeoSoi Is, Inc.CONSOLIDATION TEST
Date: AUG 97 U.O. : U.0.3247-OC
PLATE
B - 3
u.
CO
I-u.oCM
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NORMAL PRESSURE (ksf)
Boring No. B-l Depth (feet): 20.00
10
Sample: WATER @ 4 KIPS
GeoSo 1 Is, Inc*
CONSOLIDATION TEST
Date: AUG 97 U.O.: U.0.3247-OC
PLATE
B-l
CAC Associates - Lot 41
Project No. 3629-SF
September 2,1997
Page No. 45
Expansion Potential
A laboratory expansion index test of materials expected to provide foundation support was
performed-in^general accordance with the 1994 Uniform Building Code Standard 18-2. A.
remolded sample is compacted in two layers in a 4-inch I.D. mold to a total compacted
thickness of about 1.0 inch, using a 5.5-pound hammer falling 12 inches at 15 blows per
layer. The sample is initially at a saturation between 49 and 51 percent. After remolding,
the sample is confined under a normal load of 144 pounds per square foot and allowed to
soak for 24 hours. The resulting volume change due to increase in moisture content within
the sample is recorded and the Expansion Index (El) calculated.
LOCATION
B-2 @ 0-4'
SOIL TYPE
Sandy Silt with Clay
EXPANSION
INDEX
32
EXPANSION
POTENTIAL
Low
Atterberg Limits
The plastic and liquid limits of representative samples of the local soils were determined
in accordance with ASTM Test Method D-4318. The results of these test are presented
in the following page.
Medall, Aragon, Higley, Geotechnical, Inc.
PLASTICITY INDEX :(X)ru to 4^ 01 enS Q Q Q G>10
00
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10 20 30 40 50 60 70 80 90 100 11
LIQUID LIMIT (X)
Boring Depth LL(^) PL(X) PIC/.)
No. (feet)
O B-2,L.41 4 30 24 6
GeoSoi Is, Inc.
- '.'» p^' ' "' "•
ATTERBERG LIMITS"-~^3<^r4. ^-iti'-* al-^^*, . • • iv!".-i*.f*i ftftirftfrt
, .- ;.-.;-:(, 7^Q»-WWWS«*
Date: flUG 97 W.O. : U.0.3247-OC
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