HomeMy WebLinkAboutCT 08-06; HIGHLAND JAMES SUBDVIVISION; GEOTECHNICAL INVESTIGATION; DWG 483-6B; 2016-11-09•
Construction Testing & Engineering, Inc.
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* lnspection I Testing I Geotechnical I Environmental & Construction Engineering I Civil Engineering I Surveying
GEOTECHNICAL INVESTIGATION
PROPOSED 5-UNIT RESIDENTIAL SUBDIVISION
3980 HIGHLAND DRIVE
CARLSBAD, CALIFORNIA
Prepared for:
YECK INVESTMENT PROPERTIES, LLC
MS. ELIZABETH TEMPLE
3276 HIGHLAND DRIVE
CARLSBAD, CALIFORNIA 92008
Prepared by:
CONSTRUCTION TESTING & ENGINEERING, INC.
1441 MONTIEL ROAD, SUITE 115
ESCONDIDO, CALIFORNIA 92026
CTE JOB NO.: 10-129980
NOV 18 2016
November 9, 2016
1441 Montie!Road,Sulte115 I Escondido,CA92026 I Ph(760)746-4955 I Fax(760)746-9806 I www.cte-inc.net
TABLE OF CONTENTS
1.0 INTRODUCTION AND SCOPE OF SERVICES ................................................................... l
I.I Introduction ................................................................................................................... I
1.2 Scope of Services .......................................................................................................... 1
2.0 SITE DESCRIPTION ............................................................................................................... 2
3.0 FIELD INVESTIGATION AND LABORATORY TESTING ................................................ 2
3.1 Field Investigation ........................................................................................................ 2
3.2 Laboratory Testing ........................................................................................................ 3
3.3 Percolation Testing ....................................................................................................... 3
4.0 GEOLOGY ............................................................................................................................... 4
4.1 General Setting ............................................................................................................. 4
4.2 Geologic Conditions ..................................................................................................... 5
4.2.1 Quaternary Undocumented Fill (unmapped) ................................................. 5
4.2.2 Quaternary Old Paralic Deposits (Qop) ......................................................... 5
4.3 Groundwater Conditions ............................................................................................... 5
4.4 Geologic Hazards .......................................................................................................... 6
4.4.1 Surface Fault Rupture .................................................................................... 6
4.4.2 Local and Regional Faulting .......................................................................... 6
4.4.3 Liquefaction and Seismic Settlement Evaluation .......................................... 7
4.4.4 Tsunamis and Seiche Evaluation ................................................................... 8
4.4.5 Landsliding .................................................................................................... 8
4.4.6 Compressible and Expansive Soils ................................................................ 8
4.4.7 Corrosive Soils ................................................................................................ 9
5.0 CONCLUSIONS AND RECOMMENDATIONS ................................................................. 10
5.1 General ........................................................................................................................ 10
5 .2 Site Preparation........................................................................................................... 1 0
5.3 Site Excavation ........................................................................................................... 11
5.4 Fill Placement and Compaction .................................................................................. 11
5.5 Fill Materials ............................................................................................................... 12
5.6 Temporary Construction Slopes ................................................................................. 13
5.7 Foundations and Slab Recommendations ................................................................... 13
5.7.1 Foundations .................................................................................................. 14
5.7.2 Foundation Settlement ................................................................................. 15
5.7.3 Foundation Setback ...................................................................................... 15
5.7.4 Interior Concrete Slabs ................................................................................ 15
5.8 Seismic Design Criteria .............................................................................................. 16
5.9 Lateral Resistance and Earth Pressures ...................................................................... 17
5. l O Exterior Flatwork ...................................................................................................... 19
5 .11 Pavements ................................................................................................................. 20
5.12 Drainage .................................................................................................................... 21
5.13 Slopes ........................................................................................................................ 22
5 .14 Plan Review .............................................................................................................. 22
5.15 Construction Observation ......................................................................................... 22
6.0 LIMITATIONS OF INVESTIGATION ................................................................................. 23
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FIGURES
FIGURE 1
FIGURE2
FIGURE3
FIGURE4
APPENDICES
APPENDIX A
APPENDIXB
APPENDIXC
APPENDIXD
APPENDIXE
SITE LOCATION MAP
GEOLOGIC/EXPLORATION LOCATION MAP
REGIONAL FAULT AND SEISMICITY MAP
CONCEPTUAL RETAINING WALL DRAINAGE
REFERENCES
FIELD EXPLORATION METHODS LOGS
LABORATORY METHODS AND RESULTS
STANDARD GRADING SPECIFICATIONS
SITE INSPECTION REPORT BY SOIL TESTERS
Geotechnical Investigation Page 1
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016 CTE Job No.: 10-12998G
1.0 INTRODUCTION AND SCOPE OF SERVICES
1.1 Introduction
This report presents the results of the geotechnical investigation, performed by Construction Testing
and Engineering, Inc. (CTE), and provides preliminary conclusions and recommendations for the
proposed improvements at the subject site located in Carlsbad, California. This investigation was
performed to supplement the previous field investigation performed by Soil Testers (2005) which is
attached in Appendix E. Information from the test pit logs and laboratory data from the previous
study is incorporated into this report, as applicable. This investigation was performed in general
accordance with the terms of CTE proposal G-3702B, dated September 23, 2016.
CTE understands the proposed site improvements are to consist of five residential structures with
associated parking, utilities, landscaping, and other ancillary improvements. Preliminary
recommendations for excavations, fill placement, and foundation design for the proposed
improvements are presented in this report. Additionally, percolation test results are provided from
previous testing. Reviewed references are provided in Appendix A.
1.2 Scope of Services
The scope of services provided included:
• Review of readily available geologic and geotechnical reports.
• Coordination of utility mark-out and location.
• Excavation of exploratory borings and soil sampling utilizing limited-access manually operated
excavation equipment.
• Laboratory testing of selected soil samples.
• Description of site geology and evaluation of potential geologic hazards.
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Geotechnical Investigation Page2
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California'
November 9, 2016 CTE Job No.: 10-12998G
• Engineering and geologic analysis.
• Preparation of this geotechnical investigation report.
2.0 SITE DESCRIPTION
The project site is located at 3980 Highland Drive in Carlsbad, California (Figure 1). The site is
bounded by Highland Drive to the southwest and James Drive to the northeast with residential
structures to the northwest and southeast. The project area generally descends to the northeast with
elevations ranging from approximately 168 feet msl (above mean sea level) in the southwestern
portion of the site to approximately 132 feet msl to the eastern portion of the site.
3.0 FIELD INVESTIGATION AND LABORATORY TESTING
3.1 Field Investigation
CTE performed the recent field investigation on October 11, 2016. The field work consisted of site
reconnaissance, and excavation of six borings. Due to limited access conditions, the explorations
were excavated utilizing a manually operated three-inch diameter auger that was advanced to a depth
of approximately 7 .0 feet below the ground surface (bgs ). Bulk samples were collected from the
cuttings.
The soils were logged in the field by a CTE Geologist and were visually classified in general
accordance with the Unified Soil Classification System. The field descriptions have been modified,
where appropriate, to reflect laboratory test results. Boring logs, including descriptions of the soils
encountered, are included in Appendix B. The approximate locations of the borings are presented on
Figure 2.
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
3.2 Laboratory Testing
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CTE Job No.: 10-12998G
Laboratory tests were conducted on selected soil samples for classification purposes, and to evaluate
physical properties and engineering characteristics. Laboratory tests included: Gradation and
Chemical Characteristics. Test descriptions and laboratory test results for the selected soils are
included in Appendix C.
3.3 Percolation Testing
CTE previously performed three percolation tests in specified areas of the site in general accordance
with the County of San Diego Department of Environmental Health (SD DEH) procedures. The
percolation test holes were excavated with a manually operated hand-auger on March 3, 2016 to
depths ranging from approximately 2.0 to 4.0 feet below existing grade. The percolation tests were
performed in accordance with SD DEH Case I and III methods. The Case I method is performed
when presoak water remains in the test hole overnight and Case III is performed when presoak water
percolates through the test hole overnight. The approximate percolation test locations are presented
on Figure 2. The percolation test results are presented in the table below. The infiltration rates are
presented without a factor of safety applied.
Test Soil Type San Diego Depth Percolation Rate Infiltration
Location County (ft) (minutes/inch) Rate (inches
Percolation per hour)
Procedure
P-1 Qo Case III 2.0 21 0.5
P-2 Qo Case III 2.0 10 1.1
P-3 Qo Case I 7.0 480 0.02
Qop = Quaternary Old Paralic Deposits
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
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The percolation test results were obtained in accordance with City and County standards and
performed with the standard of care practiced by other professionals practicing in the area.
However, percolation test results can significantly vary laterally and vertically due to slight changes
in soil type, degree of weathering, secondary mineralization, and other physical and chemical
variabilities. As such, the test results are considered to be an estimate of percolation and converted
infiltration rates for design purposes. No guarantee is made based on the percolation testing related
to the actual functionality or longevity of associated infiltration basins or other BMP devices
designed from the presented infiltration rates.
4.0GEOLOGY
4.1 General Setting
Carlsbad is located within the Peninsular Ranges physiographic province that is characterized by
northwest-trending mountain ranges, intervening valleys, and predominantly northwest trending
regional faults. The greater San Diego Region can be further subdivided into the coastal plain area,
a central mountain-valley area and the eastern mountain valley area. The project site is located
within the coastal plain area that is characterized by Cretaceous, Tertiary, and Quaternary
sedimentary deposits that onlap an eroded basement surface consisting of Jurassic and Cretaceous
crystalline rocks.
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Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
4.2 Geologic Conditions
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CTE Job No.: 10-129980
Based on the regional geologic map prepared by Kennedy and Tan (2007), the near surface geologic
unit underlying the site consists of Quaternary Old Paralic Deposits, Unit 2-4. Based on the recent
explorations, Undocumented Fill was observed overlying the Quaternary Old Paralic Deposits.
Descriptions of the geologic and soil units encountered are presented below.
4.2.1 Quaternary Undocumented Fill (unmapped)
Where observed, the Quaternary Undocumented Fill generally consists ofloose to medium
dense, reddish brown, fine grained silty to clayey sand. This unit was observed to a depth of
less than one foot bgs during the investigation, however, localized deeper fills will likely be
encountered during grading and construction.
4.2.2 Quaternary Old Paralic Deposits (Qop)
Quaternary Old Paralic Deposits were found to be the underlying geologic unit at the site.
Where observed, these materials generally consist of medium dense to dense, reddish brown
to light reddish brown clayey to silty fine grained sandstone.
4.3 Groundwater Conditions
While groundwater conditions may vary, especially following periods of sustained precipitation or
irrigation, it is generally not anticipated to affect the proposed construction activities or completed
improvements, if proper site drainage is designed, installed, and maintained as per the
recommendations of the project civil engineer of record.
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
4.4 Geologic Hazards
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Geologic hazards that were considered to have potential impacts to site development were evaluated
based on field observations, literature review, and laboratory test results. It appears that the geologic
hazards at the site are primarily limited to those caused by shaking from earthquake-generated
ground motions. The following paragraphs discuss the geologic hazards considered and their
potential risk to the site.
4.4.1 Surface Fault Rupture
Based on the site reconnaissance and review of referenced literature, the site is not within a
State of California-designated Alquist-Priolo Earthquake Fault Studies Zone or Local
Special Studies Zone and no known active fault traces underlie, or project toward, the site.
According to the California Division of Mines and Geology, a fault is active if it displays
evidence of activity in the last 11,000 years (Hart and Bryant, revised 2007). Therefore, the
potential for surface rupture from displacement or fault movement beneath the proposed
improvements is considered to be low.
4.4.2 Local and Regional Faulting
The California Geological Survey (CGS) and the United States Geological Survey (USGS)
broadly group faults as "Class A" or "Class B" (Cao, 2003; Frankel et al., 2002). Class A
faults are generally identified based upon relatively well-defined paleoseismic activity, and a
fault-slip rate of more than 5 millimeters per year (mm/yr). In contrast, Class B faults have
comparatively less defined paleoseismic activity and are considered to have a fault-slip rate
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November 9, 2016
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less than 5 mm/yr. The nearest known Class B fault is the Rose Canyon Fault, which is
approximately 8.9 kilometers west of the site (Blake, T.F., 2000). The nearest known Class
A fault is the Temecula segment of the Elsinore Fault, which is located approximately 38.4
kilometers east of the site.
The site could be subjected to significant shaking in the event of a major earthquake on any
of the faults noted above or other faults in the southern California or northern Baja California
area.
4.4.3 Liquefaction and Seismic Settlement Evaluation
Liquefaction occurs when saturated fine-grained sands or silts lose their physical strengths
during earthquake-induced shaking and behave like a liquid. This is due to loss of
point-to-point grain contact and transfer of normal stress to the pore water. Liquefaction
potential varies with water level, soil type, material gradation, relative density, and probable
intensity and durntion of ground shaking. Seismic settlement can occur with or without
liquefaction; it results from densification of loose soils.
The site is underlain at shallow depths by dense Old Paralic Deposits. In addition, loose
surficial soils within proposed improvement areas are to be overexcavated and compacted as
engineered fill. Therefore, the potential for liquefaction or significant seismic settlement at
the site is considered to be low.
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
4.4.4 Tsunamis and Seiche Evaluation
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According to State of California Emergency Management Agency mapping, the site is not
located within a tsunami inundation zone based on distance from the coastline and elevation
above sea level. Damage resulting from oscillatory waves (seiches) is considered unlikely
due to the absence of nearby confined bodies of water.
4.4.5 Landsliding
According to mapping by Tan (1995), the site is considered to be "Generally Susceptible" to
landsliding, however, no landslides are mapped in the site area. In addition, landslides or
similar associated features were not observed during the recent field exploration. Based on
the investigation findings, landsliding is not considered to be a significant geologic hazard at
the site.
4.4.6 Compressible and Expansive Soils
Undocumented Fill Soils are considered to be potentially compressible. Therefore, these
soils should be overexcavated, processed, and placed as a properly compacted fill as
recommended herein. Based on the field data, previous laboratory testing, and site
observations, the underlying formational deposits are not considered to be subject to
significant compressibility under the proposed loads.
Based on observation and previous laboratory test results, soils at the site are generally
anticipated to exhibit Very Low to Low expansion potential (Expansion Index of 50 or less).
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November 9, 2016
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CTE Job No.: 10-12998G
Therefore, expansive soils are not anticipated to present significant adverse impacts to site
development. Additional evaluation of near-surface soils should be performed based on field
observations during grading activities.
4.4.7 Corrosive Soils
Chemical testing was performed to evaluate the potential effects that site soils may have on
concrete foundations and various types of buried metallic utilities. Soil environments
detrimental to concrete generally have elevated levels of soluble sulfates and/or pH levels
less than 5.5. According to American Concrete Institute (ACI) Table 318 4.3. l, specific
guidelines have been provided for concrete where concentrations of soluble sulfate (S04) in
soil exceed 0.1 percent by weight. These guidelines include low water: cement ratios,
increased compressive strength, and specific cement type requirements.
Based on the results of the Sulfate and pH testing performed, onsite soils are anticipated to
generally have a negligible corrosion potential to Portland cement concrete improvements.
A minimum resistivity value less than approximately 5,000 ohm-cm, and/or soluble chloride
levels in excess of 200 ppm generally indicate a corrosive environment to buried metallic
utilities and untreated conduits. Based on the obtained resistivity value of 5,010 ohm-cm
and soluble chloride level of 43.2 ppm, onsite soils are anticipated to have a moderate
corrosion potential for buried uncoated/unprotected metallic conduits. Based on these
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
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results, at a minimum, the use of buried plastic piping or conduits would appear logical and
beneficial, where feasible.
The results of the chemical tests performed are presented in the attached Appendix C.
However, CTE does not practice corrosion engineering. Therefore, a corrosion engineer or
other qualified consultant could be contacted if site specific corrosivity issues are of concern.
5.0 CONCLUSIONS AND RECOMMENDATIONS
5.1 General
CTE concludes that the proposed improvements at the site are feasible from a geotechnical
standpoint, provided the recommendations in this report are incorporated into the design and
construction of the project. Recommendations for the proposed earthwork and improvements are
included in the following sections and Appendix D. However, recommendations in the text of this
report supersede those presented in Appendix D should variations exist. These recommendations
should either be evaluated as appropriate and/or updated during or following rough grading at the
site.
5.2 Site Preparation
Prior to grading, the proposed improvement areas should be cleared of existing debris and
deleterious materials. Vegetation and other materials not suitable for structural backfill should be
properly disposed of off site. In areas to receive structures, existing undocumented fills and any
loose or disturbed soils should be removed to the depth of competent native material. In order to
provide relatively uniform conditions under proposed structures, overexcavation should extend to a
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minimum depth of two feet below proposed foundations. Where feasible, overexcavation should
extend laterally at least five feet beyond the limits of the proposed improvements, or a distance equal
to the depth of the overexcavation, whichever is greater.
Overexcavation in proposed pavement or flatwork areas should be conducted to a minimum depth of
two feet below proposed grade or to competent underlying materials, whichever depth is shallower.
A CTE representative should observe the exposed ground surface prior to placement of compacted
fill to document and verify the competency of the encountered sub grade materials. After approval
by this office, the exposed subgrades to receive fill should be scarified a minimum of nine inches,
moisture conditioned, and properly compacted prior to fill placement.
5.3 Site Excavation
Generally, excavation of site materials may be accomplished with heavy-duty construction
equipment under normal conditions. However, the Old Paralic Deposits are locally very granular
and could be sensitive to caving and/or erosion, and may not effectively remain standing vertical,
even at shallow or minor heights.
5.4 Fill Placement and Compaction
Granular fill and backfill should be compacted to a minimum relative compaction of 90 percent at a
moisture content of at least two percent above optimum, as evaluated by ASTM D 1557. The
optimum lift thickness for fill soil will depend on the type of compaction equipment used.
Generally, backfill should be placed in uniform, horizontal lifts not exceeding eight inches in loose
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
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thickness. Fill placement and compaction should be conducted in conformance with local
ordinances.
5.5 Fill Materials
Properly moisture-conditioned very low to low expansion potential soils derived from the on-site
excavations are considered suitable for reuse on the site as compacted fill. If used, these materials
should be screened of organics and materials generally greater than three inches in maximum
dimension. Irreducible materials greater than three inches in maximum dimension should generally
not be used in shallow fills ( within three feet of proposed grades). In utility trenches, adequate
bedding should surround pipes.
Imported fill beneath structures, flatwork, and pavements should have an Expansion Index of 20 or
less (ASTM D 4829). Imported fill soils for use in structural or slope areas should be evaluated by
the geotechnical engineer before being imported to the site.
Retaining wall backfill located within a 45-degree wedge extending up from the heel of the wall
should consist of soil having an Expansion Index of 20 or less (ASTM D 4829) with less than 30
percent passing the No. 200 sieve. The upper 12 to 18 inches of wall backfill could consist oflower
permeability soils, in order to reduce surface water infiltration behind walls. The project structural
engineer and/or architect should detail proper wall backdrains, including gravel drain zones, fills,
filter fabric, and perforated drain pipes. A conceptual wall backdrain detail, which may be suitable
for use at the site, is provided as Figure 4.
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Proposed 5-Unit Residential Subdivision
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November 9, 2016 CTE Job No.: 10-12998G
5.6 Temporary Construction Slopes
The following recommended slopes should be relatively stable against deep-seated failure, but may
experience localized sloughing. On-site soils are considered Type B and Type C soils with
recommended slope ratios as set forth in Table 5.6. However, due to the at least locally granular and
erodible nature of the onsite soils, maximum 1.5: 1 temporary slopes are anticipated to be more
reliable, and vertical excavations may not remain standing.
TABLE5.6 .. .. ·· .. ··
. REQqMMENDED !EMPORARY SLO;PE RATIOS
,:,1;}
SOIL TYPE
B (Old Paralic Deposits)
C (Undocumented Fill)
SLOPE RATIO
(Horizontal: vertical)
1:1 (OR FLATTER)
1.5:1 (OR FLATTER)
MAXIMUM HEIGHT
10 Feet
10 Feet
Actual field conditions and soil type designations must be verified by a "competent person" while
excavations exist, according to Cal-OSHA regulations. In addition, the above sloping
recommendations do not allow for surcharge loading at the top of slopes by vehicular traffic,
equipment or materials. Appropriate surcharge setbacks must be maintained from the top of all
unshored slopes.
5.7 Foundations and Slab Recommendations
The following recommendations are for preliminary design purposes only. These recommendations
should be reviewed after completion of earthwork to document that conditions exposed are as
anticipated and that the recommended structure design parameters are appropriate.
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
5. 7 .1 Foundations
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CTE Job No.: 10-12998G
Following the preparatory grading recommended herein, continuous and isolated spread
footings are anticipated to be suitable for use at this site. It is anticipated that the proposed
footings will be founded entirely on at least 24 inches of properly compacted fill placed as
recommended herein. Footings should not straddle cut-fill interfaces. If deeper footings are
proposed, additional overexcavation and compaction may be recommended in order to
provide a minimum of 24 inches of fill beneath all foundation elements.
Foundation dimensions and reinforcement should be based on an allowable bearing value of
2,500 pounds per square foot for footings founded in suitable fill materials and embedded a
minimum of 18 inches below the lowest adjacent rough subgrade elevation. Continuous
footings should be at least 15 inches wide; isolated footings should be at least 24 inches in
least dimension. The above bearing values may be increased by one third for short duration
loading which includes the effects of wind or seismic forces.
Minimum footing reinforcement for continuous footings should consist of four No. 4
reinforcing bars; two placed near the top and two placed near the bottom, or as per the
project structural engineer. The structural engineer should design isolated footing
reinforcement. Footing excavations should generally be maintained above optimum moisture
content until concrete placement.
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5. 7.2 Foundation Settlement
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The maximum total static settlement is expected to be on the order of one inch and the
maximum differential static settlement is expected to be on the order of 1/z inch over a
distance of approximately 40 feet. Due to the absence of a shallow groundwater table and
the dense to very dense nature of underlying materials, dynamic settlement is not expected to
adversely affect the proposed improvements.
5. 7 .3 Foundation Setback
Footings for structures should be designed such that the horizontal distance from the face of
adjacent slopes to the outer edge of the footing is at least 10 feet. In addition, footings
should bear beneath a 1: 1 plane extended up from the nearest bottom edge of adjacent
trenches and/or excavations. Deepening of affected footings may be a suitable means of
attaining the prescribed setbacks.
5.7.4 Interior Concrete Slabs
Lightly loaded concrete slabs should be a minimum of 4.5 inches. Minimum slab
reinforcement should consist of #4 reinforcing bars placed on maximum 18-inch centers each
way, at above mid-slab height, but with proper cover. Slabs subjected to heavier loads may
require thicker slab sections and/or increased reinforcement. Subgrade materials should be
maintained above optimum moisture content until slab underlayment or concrete are placed.
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
Page 16
CTE Job No.: 10-129980
In moisture-sensitive floor areas, a suitable vapor retarder of at least ten-mil thickness (with
all laps or penetrations sealed or taped) overlying a four-inch layer of consolidated minimum
1/z-inch crushed aggregate gravel should be installed per the current building code. An
optional maximum two-inch layer of similar aggregate material may be placed above the
vapor retarder to further protect the membrane during steel and concrete placement, if
desired. This recommended moisture protection is generally considered typical of the area.
However, CTE is not an expert at preventing moisture penetration through slabs. If
proposed floor areas or coverings are considered especially sensitive to moisture emissions,
additional recommendations from a specialty consultant could be obtained. A qualified
architect or other experienced professional should be contacted if moisture penetration is a
more significant concern.
5.8 Seismic Design Criteria
The seismic ground motion values listed in the table below were derived in accordance with the
ASCE 7-10 Standard and 2013 CBC. This was accomplished by establishing the Site Class based on
the soil properties at the site, and then calculating the site coefficients and parameters using the
United States Geological Survey Seismic Design Maps application using the site coordinates of
33.1536 degrees latitude and-117.3289 degrees longitude. These values are intended for the design
of structures to resist the effects of earthquake ground motions.
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
:::,. :./:·;····· ':· :·
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TABLE5.9
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PARAMETER VALUE
Site Class D
Mapped Spectral Response 1.128 Acceleration Parameter, Ss
Mapped Spectral Response 0.433 Acceleration Parameter, S1
Seismic Coefficient, Fa 1.049
Seismic Coefficient, Fv 1.567
MCE Spectral Response 1.183 Acceleration Parameter, SMs
MCE Spectral Response 0.678 Acceleration Parameter, SM1
Design Spectral Response 0.789 Acceleration, Parameter Sns
Design Spectral Response 0.452 Acceleration, Parameter Sm
Peak Ground Acceleration PGAM 0.469
5.9 Lateral Resistance and Earth Pressures
Page 17
CTE Job No.: 10-12998G
·:
:. -'
CBC REFERENCE (2013)
ASCE 7, Chapter 20
Figure 1613.3.1 (1)
Figure 1613.3.1 (2)
Table 1613.3.3 (1)
Table 1613.3.3 (2)
Section 1613.3.3
Section 1613.3.3
Section 1613.3.4
Section 1613.3.4
ASCE 7, Section 11.8.3
Lateral loads acting against structures may be resisted by friction between the footings and the
supporting soil or passive pressure acting against structures. If frictional resistance is used, we
recommend allowable coefficients of friction of0.30 (total frictional resistance equals the coefficient
of friction multiplied by the dead load) for concrete cast directly against compacted fill. A design
passive resistance value of 250 pounds per square foot per foot of depth (with a maximum value of
1,250 pounds per square foot) may be used. The allowable lateral resistance can be taken as the sum
of the frictional resistance and the passive resistance, provided the passive resistance does not
exceed two-thirds of the total allowable resistance.
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
Page 18
CTE Job No.: 10-129980
Retaining walls up to approximately eight feet high and backfilled using granular soils ( either select
onsite or suitable import) may be designed using the 'equivalent fluid weights given in Table 5.9
below.
SLOPE BACKFILL
WALL TYPE LEVEL BACKFILL 2:1 (HORIZONTAL:
VERTICAL)
CANTILEVER WALL 30 48 (YIELDING)
RESTRAINED WALL 60 75
Lateral pressures on cantilever retaining walls (yielding walls) over six feet high due to earthquake
motions may be calculated based on work by Seed and Whitman (1970). The total lateral thrust
against a properly drained and backfilled cantilever retaining wall above the groundwater level can
be expressed as:
For non-yielding ( or "restrained") walls, the total lateral thrust may be similarly calculated
based on work by Wood (1973):
Where PA = Static Active Thrust (given previously Table 5.9)
PK= Static Restrained Wall Thrust (given previously Table 5.9)
L1P AE = Dynamic Active Thrust Increment = (3/8) kh yH2
L1PKE = Dynamic Restrained Thrust Increment = kh yH2
\ \Esc _ server\proj ects\ 1 0-12000 to 1 0-12999 Projects\ 1 0-129980\Rpt_ Geotechnical. doc
Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
kh = 2/3 Peak Ground Acceleration = 2/3 (PGAM)
H = Total Height of the Wall
Page 19
CTE Job No.: 10-12998G
y = Total Unit Weight of Soil;::; 135 pounds per cubic foot
The increment of dynamic thrust in both cases should be distributed trapezoidally with a line of
action located at 0.3H above the bottom of the wall.
These values assume non-expansive backfill and free-draining conditions. Measures should be taken
to prevent moisture buildup behind all retaining walls. Drainage measures should include free-
draining backfill materials and sloped, perforated drains. These drains should discharge to an
appropriate off-site location. Figure 4 shows conceptual wall drainage details that may be
appropriate for proposed walls at the subject site. Waterproofing should be as specified by the
project architect.
5 .10 Exterior Flatwork
To reduce the potential for cracking in exterior flatwork for non-traffic areas caused by minor
movement of subgrade soils and typical concrete shrinkage, it is recommended that such flatwork
measure a minimum 4.5 inches thick and be installed with crack-control joints at appropriate spacing
as designed by the project architect. Additionally, it is recommended that flatwork be installed with
at least No. 3 reinforcing bars on maximum 18-inch centers, each way, at above mid-height of slab
but with proper concrete cover, or other reinforcement per the project consultants. Doweling of
flatwork joints at critical pathways or similar could also be beneficial in resisting minor sub grade
movements.
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
Page 20
CTE Job No.: 10-12998G
All subgrades should be prepared according to the earthwork recommendations previously given
before placing concrete. Positive drainage should be established and maintained next to all flatwork.
Subgrade materials shall be maintained at, or be elevated to, above optimum moisture content prior
to concrete placement.
5 .11 Pavements
If proposed at near grade elevations, pavement sections provided are based on an estimated
Resistance "R" -Value and traffic indices, and the assumption that the upper foot of compacted fill
subgrade and overlying aggregate base materials are properly compacted to a minimum 95% relative
compaction at a minimum of two percent above optimum moisture content (as per ASTM D 1557).
Beneath proposed pavement areas, loose or otherwise unsuitable soils are to be removed to the depth
of competent native material as recommended in Section 5.2.
Traffic Area Assumed Preliminary Asphalt Pavements Portland Cement
Traffic Index Subgrade AC CalTrans Class II or Concrete
"R"-Value Thickness Crushed Miscellaneous Pavements On
(INCHES) Aggregate Base Subgrade
Thickness (INCHES)
INCHES)
Auto Parking 5.0 20+ 3.0 6.0 6.5
Areas
Moderate Drive 6.0 20+ 4.0 9.0 7.0
Areas
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
Page 21
CTE Job No.: 10-129980
Asphalt paved areas should be designed, constructed, and maintained in accordance with, for
example, the recommendations of the Asphalt Institute, or other widely recognized authority.
Concrete paved areas should be designed and constructed in accordance with the recommendations
of the American Concrete Institute or other widely recognized authority, particularly with regard to
thickened edges,joints, and drainage. The Standard Specifications for Public Works construction
("Greenbook") or Caltrans Standard Specifications may be referenced for pavement materials
specifications.
5 .12 Drainage
Surface runoff should be collected and directed away from improvements by means of appropriate
erosion-reducing devices, and positive drainage should be established around proposed
improvements. Positive drainage should be directed away from improvements and slope areas at a
minimum gradient of two percent for a distance of at least five feet. However, the project civil
engineer should evaluate the on-site drainage and make necessary provisions to keep surface water
from affecting the site.
Generally, CTE recommends against allowing water to infiltrate building pads or adjacent to slopes
and improvements. However, it is understood that some agencies are encouraging the use of storm-
water cleansing devices. Therefore, if storm water cleansing devices must be used, it is generally
recommended that they be underlain by an impervious barrier and that the infiltrate be collected via
subsurface piping and discharged off site. If infiltration must occur, water should infiltrate as far
away from structural improvements as feasible. Additionally, any reconstructed slopes descending
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
Page 22
CTE Job No.: 10-12998G
from infiltration basins should be equipped with subdrains to collect and discharge accumulated
subsurface water (Appendix D contains general or typical details for internal fill slope drainage).
5.13 Slopes
Based on observed conditions and anticipated soil strength characteristics, cut and fill slopes should
be constructed at ratios of 2: 1 (horizontal: vertical) or flatter. These fill slope inclinations should
exhibit factors of safety greater than 1.5.
Although properly constructed slopes on this site should be grossly stable, the soils will be
somewhat erodible. Therefore, runoff water should not be permitted to drain over the edges of
slopes unless that water is confined to properly designed and constructed drainage facilities.
Erosion-resistant vegetation should be maintained on the face of all slopes. Typically, soils along
the top portion of a fill slope face will creep laterally. CTE recommends against building distress-
sensitive hardscape improvements within five feet of slope crests.
5 .14 Plan Review
CTE should be authorized to review the project grading, shoring, and foundation plans, prior to
commencement of earthwork to identify potential conflicts with the intent of the geotechnical
recommendations.
5 .15 Construction Observation
The recommendations provided in this report are based on preliminary design information for the
proposed construction and the subsurface conditions observed in the explorations performed. The
interpolated subsurface conditions should be checked in the field during construction to verify that
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Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
Page 23
CTE Job No.: 10-12998G
conditions are as anticipated. Foundation recommendations may be revised upon completion of
grading and as-built laboratory test results.
Recommendations provided in this report are based on the understanding and assumption that CTE
will provide the observation and testing services for the project. Earthwork should be observed and
tested to verify that grading activities have been performed according to the recommendations
contained within this report. CTE should evaluate all footing trenches before reinforcing steel
placement.
6.0 LIMITATIONS OF INVESTIGATION
The field evaluation, laboratory testing, and geotechnical analysis presented in this report have been
conducted according to current engineering practice and the standard of care exercised by reputable
geotechnical consultants performing similar tasks in this area. No other warranty, expressed or
implied, is made regarding the conclusions, recommendations and opinions expressed in this report.
Variations may exist and conditions not observed or described in this report may be encountered
during construction.
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
Page 24
CTE Job No.: 10-129980
The findings of this report are valid as of the present date. However, changes in the conditions of a
property can occur with the passage of time, whether they are due to natural processes or the works
of man on this or adjacent properties. In addition, changes in applicable or appropriate standards
may occur, whether they result from legislation or the broadening of knowledge. Accordingly, the
findings of this report may be invalidated wholly or partially by changes outside our control.
Therefore, this report is subject to review and should not be relied upon after a period of three years.
CTE's conclusions and recommendations are based on an analysis of the observed conditions. If
conditions different from those described in this report are encountered, this office should be notified
and additional recommendations, if required, will be provided.
The opportunity to be of service on this project is appreciated. If you have any questions regarding
this report, please do not hesitate to contact the undersigned.
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Geotechnical Investigation
Proposed 5-Unit Residential Subdivision
3980 Highland Drive, Carlsbad, California
November 9, 2016
Respectfully submitted,
Page 25
CTE Job No.: 10-12998G
CONSTRUCTION TESTING & ENGINEERING, INC.
Dan T. Math, GE #2665
Principal Engineer
Aaron J. Beeby, CEG #2603
Project Geologist
AJB/JFL/DTM:nri
Jay F. Lynch, CEG #1890
Principal Engineering Geologist
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SITE INDEX MAP
PROPOSED 5-UNIT RESIDENTIAL SUBDIVISION
3980 HIGHLAND DRIVE CARL'lBAD, CAUFORNIA
SCALE:
AS SHOIN
DAT£:
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GBOLOGIC/BXPLORATION LOCATION KAP
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3980 filGHLAND DRIVE
CARISBAD, CALlfORNIA
SCALE:
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DATE:
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12 0 6 12
LEGEND • -• I I
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HISTORIC FAULT DISPLACEMENT (LAST 200 YEARS)
HOLOCENE FAULT DISPLACEMENT (DURING PAST 11,700 YEARS)
LATE QUATERNARY FAULT DISPLACMENT (DURING PAST 700,000 YEARS)
QUATERNARY FAULT DISPLACEMENT (AGE UNDIFFERENTIATED)
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RETAINING WALL
FINISH GRADE
WALL FOOTING
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PERMEABILITY NATIVE
MATERIAL COMPACTED TO 90%
RELA TTVE COMPACTlON
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RETAINING WALL DRAINAGE DETAIL ALE· NO SCALE
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APPENDIX A
REFERENCES
REFERENCES
1. American Society for Civil Engineers, 2010, "Minimum Design Loads for Buildings and
Other Structures," ASCE/SEI 7-10.
2. ASTM, 2002, "Test Method for Laboratory Compaction Characteristics of Soil Using
Modified Effort," Volume 04.08
3. Blake, T.F., 2000, "EQFAULT," Version 3.00b, Thomas F. Blake Computer Services and
Software.
4. California Building Code, 2013, "California Code of Regulations, Title 24, Part 2, Volume 2
of2," California Building Standards Commission, published by ICBO, June.
5. California Division of Mines and Geology, CD 2000-003 "Digital Images of Official Maps
of Alquist-Priolo Earthquake Fault Zones of California, Southern Region," compiled by
Martin and Ross.
6. California Emergency Management Agency/California Geological Survey, "Tsunami
Inundation Maps for Emergency Planning.
7. County of San Diego Department of Environmental Health Land and Water Quality
Division, 2010, Design Manual for Onsite Wastewater Treatment Systems dated March 22
updated November 25, 2013.
8. Frankel, A.D., Petersen, M.D., Mueller, C.S., Haller, K.M., Wheeler, R.L., Leyendecker,
E.V., Wesson, R. L., Harmsen, S.C., Cramer, C.H., Perkins, D.M., Rukstales,K.S.,2002,
Documentation for the 2002 update of the National Seismic Hazard Maps: U.S. Geological
Survey Open-File Report 2002-420, 39p
9. Hart, Earl W., Revised 2007, "Fault-Rupture Hazard Zones in California, Alquist Priolo,
Special Studies Zones Act of 1972," California Division of Mines and Geology, Special
Publication 42.
10. Jennings, Charles W., 1994, "Fault Activity Map of California and Adjacent Areas" with
Locations and Ages of Recent Volcanic Eruptions.
11. Kennedy, M.P. and Tan, S.S., 2008, "Geologic Map of the Oceanside 30' x 60' Quadrangle,
California", California Geological Survey, Map No. 2, Plate 1 of 2.
12. Reichle, M., Bodin, P., and Brune, J., 1985, The June 1985 San Diego Bay Earthquake
swarm [abs.]: EOS, v. 66, no. 46, p.952.
13. SEAOC, Blue Book-Seismic Design Recommendations, "Seismically Induced Lateral Earth
Pressures on Retaining Structures and Basement Walls," Article 09.10.010, October 2013.
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14. Seed, H.B., and R.V. Whitman, 1970, "Design of Earth Retaining Structures for Dynamic
Loads," in Proceedings, ASCE Specialty Conference on Lateral Stresses in the Ground and
Design of Earth-Retaining Structures, pp. 103-147, Ithaca, New York: Cornell University.
15. Simons, R.S., 1979, Instrumental Seismicity of the San Diego area, 1934-1978, in Abbott,
P.L. and Elliott, W.J., eds., Earthquakes and other perils, San Diego region: San Diego
Association of Geologists, prepared for Geological Society of America field trip, November
1979, p.101-105.
16. Soil Testers, 2005, Site Inspection, Proposed Residential Building Site, 3980 Highland
Avenue, City of Carlsbad, Subject: Filr No. 1106F3-05, dated September 2.
17. Tan, S. S., and Giffen, D. G., 1995, "Landslide Hazards in the Northern Part of the San
Diego Metropolitan Area, San Diego County, California: Oceanside and San Luis Rey
Quadrangles, Landslide Hazard Identification Map No. 35", California Department of
Conservation, Division of Mines and Geology, Open-File Report 95-04, State of California,
Division of Mines and Geology, Sacramento, California.
18. Wood, J.H. 1973, Earthquake-Induced Soil Pressures on Structures, Report EERL 73-05.
Pasadena: California Institute of Technology.
APPENDIXB
EXPLORATION LOGS
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• 1441 Montiel Rd Ste 115, Escondido, CA 92026 Ph (760) 746-4955
DEFINITION OF TERMS
PRIMARY DIVISIONS
GRAVELS
MORE THAN
HALF OF
COARSE
FRACTION IS
LARGER THAN
NO. 4 SIEVE
SANDS
MORE THAN
HALF OF
COARSE
FRACTION IS
SMALLER THAN
NO. 4SIEVE
CLEAN
GRAVELS
< 5% FINES
GRAVELS
WITH FINES
CLEAN
SANDS
< 5% FINES
SIL TS AND CLAYS
LIQUID LIMIT IS
LESS THAN 50
SIL TS AND CLAYS
LIQUID LIMIT IS
GREATER THAN 50
HIGHLY ORGANIC SOILS
SYMBOLS SECONDARY DIVISIONS
WELL GRADED GRAVELS, GRAVEL-SAND MIXTURES
LITTLE OR NO FINES
POORLY GRADED GRAVELS OR GRAVEL SAND MIXTURES,
LITTLE OF NO FINES
SILTY GRAVELS, GRAVEL-SAND-SILT MIXTURES,
NON-PLASTIC FINES
CLAYEY GRAVELS, GRAVEL-SAND-CLAY MIXTURES,
PLASTIC FINES
WELL GRADED SANDS, GRAVELLY SANDS, LITTLE OR NO
FINES
POORLY GRADED SANDS, GRA YELL Y SANDS, LITTLE OR
NO FINES
SILTY SANDS, SAND-SILT MIXTURES, NON-PLASTIC FINES
INORGANIC SILTS, VERY FINE SANDS, ROCK FLOUR, SILTY
OR CLAYEY FINE SANDS, SLIGHTLY PLASTIC CLAYEY SIL TS
INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY,
GRAVELLY, SANDY SILTS OR LEAN CLAYS
ORGANIC SILTS AND ORGANIC CLAYS OF LOW PLASTICITY
INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE
SANDY OR SILTY SOILS ELASTIC SILTS
INORGANIC CLAYS OF HIGH PLASTICITY, FAT CLAYS
ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY,
ORGANIC SILTY CLAYS
PEAT AND OTHER HIGHLY ORGANIC SOILS
GRAIN SIZES
BOULDERS COBBLES GRAVEL SAND SIL TS AND CLAYS COARSE FINE COARSE MEDIUM FINE
12" 3" 3/4" 4 10 40 200
CLEAR SQUARE SIEVE OPENING U.S. STANDARD SIEVE SIZE
ADDITIONAL TESTS
(OTHER THAN TEST PIT AND BORING LOG COLUMN HEADINGS)
MAX-Maximum Dry Density
GS-Grain Size Distribution
SE-Sand Equivalent
EI-Expansion Index
CHM-Sulfate and Chloride
Content , pH, Resistivity
COR -Corrosivity
SD-Sample Disturbed
PM-Permeability
SG-Specific Gravity
HA-Hydrometer Analysis
AL-Atterberg Limits
RV-R-Value
CN-Consolidation
CP-Collapse Potential
HC-Hydrocollapse
REM-Remolded
PP-Pocket Penetrometer
WA-Wash Analysis
DS-Direct Shear
UC-Unconfined Compression
MD-Moisture/Density
M-Moisture
SC-Swell Compression
01-Organic Impurities
FIGURE: BL1
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DRILLER: SHEET: of
DRILL METHOD: DRILLING DATE:
SAMPLE METHOD: ELEVATION:
BORING LEGEND Laboratory Tests
DESCRIPTION
Block or Chunk Sample
Bulk Sample
Standard Penetration Test
Modified Split-Barrel Drive Sampler (Cal Sampler)
Thin Walled Army Corp. of Engineers Sample
Groundwater Table
Soil Type or Classification Change
?---?--?--?--?--?---?-
\__ F~rmation ~hange f (A~proximat~ boundari~s queried ;?)l
Quotes are placed around classifications where the soils
exist in situ as bedrock
FIGURE: BL2
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APPENDIXC
LABORATORY METHODS AND RESULTS
APPENDIXC
LABORATORY METHODS AND RESULTS
Laboratory Testing Program
Laboratory tests were performed on representative soil samples to detect their relative engineering
properties. Tests were performed following test methods of the American Society for Testing
Materials or other accepted standards. The following presents a brief description of the various test
methods used.
Classification
Soils were classified visually according to the Unified Soil Classification System. Visual
classifications were supplemented by laboratory testing of selected samples according to ASTM
D2487. The soil classifications are shown on the Exploration Logs in Appendix B.
Particle-Size Analysis
Particle-size analyses were performed on selected representative samples according to ASTM D 422.
Chemical Analysis
Soil materials were collected with sterile sampling equipment and tested for Sulfate and Chloride
content, pH, Corrosivity, and Resistivity.
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(feet) ppm
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LOCATION DEPTH RESULTS
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APPENDIXD
STANDARD SPECIFICATIONS FOR GRADING
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AppendixD Page D-1
Standard Specifications for Grading
Section 1 -General
Construction Testing & Engineering, Inc. presents the following standard recommendations for
grading and other associated operations on construction projects. These guidelines should be
considered a portion of the project specifications. Recommendations contained in the body of
the previously presented soils report shall supersede the recommendations and or requirements as
specified herein. The project geotechnical consultant shall interpret disputes arising out of
interpretation of the recommendations contained in the soils report or specifications contained
herein.
Section 2 -Responsibilities of Project Personnel
The geotechnical consultant should provide observation and testing services sufficient to general
conformance with project specifications and standard grading practices. The geotechnical
consultant should report any deviations to the client or his authorized representative.
The Client should be chiefly responsible for all aspects of the project. He or his authorized
representative has the responsibility of reviewing the findings and recommendations of the
geotechnical consultant. He shall authorize or cause to have authorized the Contractor and/or
other consultants to perform work and/or provide services. During grading the Client or his
authorized representative should remain on-site or should remain reasonably accessible to all
concerned parties in order to make decisions necessary to maintain the flow of the project.
The Contractor is responsible for the safety of the project and satisfactory completion of all
grading and other associated operations on construction projects, including, but not limited to,
earth work in accordance with the project plans, specifications and controlling agency
requirements.
Section 3 -Preconstruction Meeting
A preconstruction site meeting should be arranged by the owner and/or client and should include
the grading contractor, design engineer, geotechnical consultant, owner's representative and
representatives of the appropriate governing authorities.
Section 4 -Site Preparation
The client or contractor should obtain the required approvals from the controlling authorities for
the project prior, during and/or after demolition, site preparation and removals, etc. The
appropriate approvals should be obtained prior to proceeding with grading operations.
STANDARD SPECIFICATIONS OF GRADING
Page 1 of 26
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Standard Specifications for Grading
Clearing and grubbing should consist of the removal of vegetation such as brush, grass, woods,
stumps, trees, root of trees and otherwise deleterious natural materials from the areas to be
graded. Clearing and grubbing should extend to the outside of all proposed excavation and fill
areas.
Demolition should include removal of buildings, structures, foundations, reservoirs, utilities
(including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, mining shafts,
tunnels, etc.) and other man-made surface and subsurface improvements from the areas to be
graded. Demolition of utilities should include proper capping and/or rerouting pipelines at the
project perimeter and cutoff and capping of wells in accordance with the requirements of the
governing authorities and the recommendations of the geotechnical consultant at the time of
demolition.
Trees, plants or man-made improvements not planned to be removed or demolished should be
protected by the contractor from damage or injury.
Debris generated during clearing, grubbing and/or demolition operations should be wasted from
areas to be graded and disposed off-site. Clearing, grubbing and demolition operations should be
performed under the observation of the geotechnical consultant.
Section 5 -Site Protection
Protection of the site during the period of grading should be the responsibility of the contractor .
Unless other provisions are made in writing and agreed upon among the concerned parties,
completion of a portion of the project should not be considered to preclude that portion or
adjacent areas from the requirements for site protection until such time as the entire project is
complete as identified by the geotechnical consultant, the client and the regulating agencies.
Precautions should be taken during the performance of site clearing, excavations and grading to
protect the work site from flooding, ponding or inundation by poor or improper surface drainage.
Temporary provisions should be made during the rainy season to adequately direct surface
drainage away from and off the work site. Where low areas cannot be avoided, pumps should be
kept on hand to continually remove water during periods of rainfall.
Rain related damage should be considered to include, but may not be limited to, erosion, silting,
saturation, swelling, structural distress and other adverse conditions as determined by the
geotechnical consultant. Soil adversely affected should be classified as unsuitable materials and
should be subject to overexcavation and replacement with compacted fill or other remedial
grading as recommended by the geotechnical consultant.
STANDARD SPECIFICATIONS OF GRADING
Page 2 of 26
AppendixD Page D-3
Standard Specifications for Grading
The contractor should be responsible for the stability of all temporary excavations.
Recommendations by the geotechnical consultant pertaining to temporary excavations ( e.g.,
backcuts) are made in consideration of stability of the completed project and, therefore, should
not be considered to preclude the responsibilities of the contractor. Recommendations by the
geotechnical consultant should not be considered to preclude requirements that are more
restrictive by the regulating agencies. The contractor should provide during periods of extensive
rainfall plastic sheeting to prevent unprotected slopes from becoming saturated and unstable.
When deemed appropriate by the geotechnical consultant or governing agencies the contractor
shall install checkdams, desilting basins, sand bags or other drainage control measures.
In relatively level areas and/or slope areas, where saturated soil and/or erosion gullies exist to
depths of greater than 1.0 foot; they should be overexcavated and replaced as compacted fill in
accordance with the applicable specifications. Where affected materials exist to depths of 1.0
foot or less below proposed finished grade, remedial grading by moisture conditioning in-place,
followed by thorough recompaction in accordance with the applicable grading guidelines herein
may be attempted. If the desired results are not achieved, all affected materials should be
overexcavated and replaced as compacted fill in accordance with the slope repair
recommendations herein. If field conditions dictate, the geotechnical consultant may
recommend other slope repair procedures.
Section 6 -Excavations
6.1 Unsuitable Materials
Materials that are unsuitable should be excavated under observation and
recommendations of the geotechnical consultant. Unsuitable materials include, but may
not be limited to, dry, loose, soft, wet, organic compressible natural soils and fractured,
weathered, soft bedrock and nonengineered or otherwise deleterious fill materials.
Material identified by the geotechnical consultant as unsatisfactory due to its moisture
conditions should be overexcavated; moisture conditioned as needed, to a uniform at or
above optimum moisture condition before placement as compacted fill.
If during the course of grading adverse geotechnical conditions are exposed which were
not anticipated in the preliminary soil report as determined by the geotechnical consultant
additional exploration, analysis, and treatment of these problems may be recommended.
STANDARD SPECIFICATIONS OF GRADING
Page 3 of 26
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Standard Specifications for Grading
6.2 Cut Slopes
Unless otherwise recommended by the geotechnical consultant and approved by the
regulating agencies, permanent cut slopes should not be steeper than 2: 1 (horizontal:
vertical).
The geotechnical consultant should observe cut slope excavation and if these excavations
expose loose cohesionless, significantly fractured or otherwise unsuitable material, the
materials should be overexcavated and replaced with a compacted stabilization fill. If
encountered specific cross section details should be obtained from the Geotechnical
Consultant.
When extensive cut slopes are excavated or these cut slopes are made in the direction of
the prevailing drainage, a non-erodible diversion swale (brow ditch) should be provided
at the top of the slope.
6.3 Pad Areas
All lot pad areas, including side yard terrace containing both cut and fill materials,
transitions, located less than 3 feet deep should be overexcavated to a depth of 3 feet and
replaced with a uniform compacted fill blanket of 3 feet. Actual depth of overexcavation
may vary and should be delineated by the geotechnical consultant during grading,
especially where deep or drastic transitions are present.
For pad areas created above cut or natural slopes, positive drainage should be established
away from the top-of-slope. This may be accomplished utilizing a berm drainage swale
and/or an appropriate pad gradient. A gradient in soil areas away from the top-of-slopes
of2 percent or greater is recommended.
Section 7 -Compacted Fill
All fill materials should have fill quality, placement, conditioning and compaction as specified
below or as approved by the geotechnical consultant.
7 .1 Fill Material Quality
Excavated on-site or import materials which are acceptable to the geotechnical consultant
may be utilized as compacted fill, provided trash, vegetation and other deleterious
materials are removed prior to placement. All import materials anticipated for use on-site
should be sampled tested and approved prior to and placement is in conformance with the
requirements outlined.
STANDARD SPECIFICATIONS OF GRADING
Page 4 of 26
AppendixD Page D-5
Standard Specifications for Grading
Rocks 12 inches in maximum and smaller may be utilized within compacted fill provided
sufficient fill material is placed and thoroughly compacted over and around all rock to
effectively fill rock voids. The amount of rock should not exceed 40 percent by dry
weight passing the 3/4-inch sieve. The geotechnical consultant may vary those
requirements as field conditions dictate.
Where rocks greater than 12 inches but less than four feet of maximum dimension are
generated during grading, or otherwise desired to be placed within an engineered fill,
special handling in accordance with the recommendations below. Rocks greater than
four feet should be broken down or disposed off-site.
7.2 Placement of Fill
Prior to placement of fill material, the geotechnical consultant should observe and
approve the area to receive fill. After observation and approval, the exposed ground
surface should be scarified to a depth of 6 to 8 inches. The scarified material should be
conditioned (i.e. moisture added or air dried by continued discing) to achieve a moisture
content at or slightly above optimum moisture conditions and compacted to a minimum
of 90 percent of the maximum density or as otherwise recommended in the soils report or
by appropriate government agencies.
Compacted fill should then be placed in thin horizontal lifts not exceeding eight inches in
loose thickness prior to compaction. Each lift should be moisture conditioned as needed,
thoroughly blended to achieve a consistent moisture content at or slightly above optimum
and thoroughly compacted by mechanical methods to a minimum of 90 percent of
laboratory maximum dry density. Each lift should be treated in a like manner until the
desired finished grades are achieved.
The contractor should have suitable and sufficient mechanical compaction equipment and
watering apparatus on the job site to handle the amount of fill being placed m
consideration of moisture retention properties of the materials and weather conditions.
When placing fill in horizontal lifts adjacent to areas sloping steeper than 5: 1 (horizontal:
vertical), horizontal keys and vertical benches should be excavated into the adjacent slope
area. Keying and benching should be sufficient to provide at least six-foot wide benches
and a minimum of four feet of vertical bench height within the firm natural ground, firm
bedrock or engineered compacted fill. No compacted fill should be placed in an area
after keying and benching until the geotechnical consultant has reviewed the area.
Material generated by the benching operation should be moved sufficiently away from
STANDARD SPECIFICATIONS OF GRADING
Page 5 of 26
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Appendix D Page D-6
Standard Specifications for Grading
the bench area to allow for the recommended review of the horizontal bench prior to
placement of fill.
Within a single fill area where grading procedures dictate two or more separate fills,
temporary slopes (false slopes) may be created. When placing fill adjacent to a false
slope, benching should be conducted in the same manner as above described. At least a
3-foot vertical bench should be established within the firm core of adjacent approved
compacted fill prior to placement of additional fill. Benching should proceed in at least
3-foot vertical increments until the desired finished grades are achieved.
Prior to placement of additional compacted fill following an overnight or other grading
delay, the exposed surface or previously compacted fill should be processed by
scarification, moisture conditioning as needed to at or slightly above optimum moisture
content, thoroughly blended and recompacted to a minimum of 90 percent of laboratory
maximum dry density. Where unsuitable materials exist to depths of greater than one
foot, the unsuitable materials should be over-excavated.
Following a period of flooding, rainfall or overwatering by other means, no additional fill
should be placed until damage assessments have been made and remedial grading
performed as described herein.
Rocks 12 inch in maximum dimension and smaller may be utilized in the compacted fill
provided the fill is placed and thoroughly compacted over and around all rock. No
oversize material should be used within 3 feet of finished pad grade and within 1 foot of
other compacted fill areas. Rocks 12 inches up to four feet maximum dimension should
be placed below the upper 10 feet of any fill and should not be closer than 15 feet to any
slope face. These recommendations could vary as locations of improvements dictate.
Where practical, oversized material should not be placed below areas where structures or
deep utilities are proposed. Oversized material should be placed in windrows on a clean,
overexcavated or unyielding compacted fill or firm natural ground surface. Select native
or imported granular soil (S.E. 30 or higher) should be placed and thoroughly flooded
over and around all windrowed rock, such that voids are filled. Windrows of oversized
material should be staggered so those successive strata of oversized material are not in
the same vertical plane.
It may be possible to dispose of individual larger rock as field conditions dictate and as
recommended by the geotechnical consultant at the time of placement.
STANDARD SPECIFICATIONS OF GRADING
Page 6 of 26
AppendixD Page D-7
Standard Specifications for Grading
The contractor should assist the geotechnical consultant and/or his representative by
digging test pits for removal determinations and/or for testing compacted fill. The
contractor should provide this work at no additional cost to the owner or contractor's
client.
Fill should be tested by the geotechnical consultant for compliance with the
recommended relative compaction and moisture conditions. Field density testing should
conform to ASTM Method of Test D 1556-00, D 2922-04. Tests should be conducted at
a minimum of approximately two vertical feet or approximately 1,000 to 2,000 cubic
yards of fill placed. Actual test intervals may vary as field conditions dictate. Fill found
not to be in conformance with the grading recommendations should be removed or
otherwise handled as recommended by the geotechnical consultant.
7.3 Fill Slopes
Unless otherwise recommended by the geotechnical consultant and approved by the
regulating agencies, permanent fill slopes should not be steeper than 2: 1 (horizontal:
vertical).
Except as specifically recommended in these grading guidelines compacted fill slopes
should be over-built two to five feet and cut back to grade, exposing the firm, compacted
fill inner core. The actual amount of overbuilding may vary as field conditions dictate. If
the desired results are not achieved, the existing slopes should be overexcavated and
reconstructed under the guidelines of the geotechnical consultant. The degree of
overbuilding shall be increased until the desired compacted slope surface condition is
achieved. Care should be taken by the contractor to provide thorough mechanical
compaction to the outer edge of the overbuilt slope surface.
At the discretion of the geotechnical consultant, slope face compaction may be attempted
by conventional construction procedures including backrolling. The procedure must
create a firmly compacted material throughout the entire depth of the slope face to the
surface of the previously compacted firm fill intercore.
During grading operations, care should be taken to extend compactive effort to the outer
edge of the slope. Each lift should extend horizontally to the desired finished slope
surface or more as needed to ultimately established desired grades. Grade during
construction should not be allowed to roll off at the edge of the slope. It may be helpful
to elevate slightly the outer edge of the slope. Slough resulting from the placement of
individual lifts should not be allowed to drift down over previous lifts. At intervals not
STANDARD SPECIFICATIONS OF GRADING
Page 7 of 26
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Appendix D Page D-8
Standard Specifications for Grading
exceeding four feet in vertical slope height or the capability of available equipment,
whichever is less, fill slopes should be thoroughly dozer trackrolled.
For pad areas above fill slopes, positive drainage should be established away from the
top-of-slope. This may be accomplished using a berm and pad gradient of at least two
percent.
Section 8 -Trench Backfill
Utility and/or other excavation of trench backfill should, unless otherwise recommended, be
compacted by mechanical means. Unless otherwise recommended, the degree of compaction
should be a minimum of90 percent of the laboratory maximum density.
Within slab areas, but outside the influence of foundations, trenches up to one foot wide and two
feet deep may be backfilled with sand and consolidated by jetting, flooding or by mechanical
means. If on-site materials are utilized, they should be wheel-rolled, tamped or otherwise
compacted to a firm condition. For minor interior trenches, density testing may be deleted or
spot testing may be elected if deemed necessary, based on review of backfill operations during
construction.
If utility contractors indicate that it is undesirable to use compaction equipment in close
proximity to a buried conduit, the contractor may elect the utilization of light weight mechanical
compaction equipment and/or shading of the conduit with clean, granular material, which should
be thoroughly jetted in-place above the conduit, prior to initiating mechanical compaction
procedures. Other methods of utility trench compaction may also be appropriate, upon review of
the geotechnical consultant at the time of construction.
In cases where clean granular materials are proposed for use in lieu of native materials or where
flooding or jetting is proposed, the procedures should be considered subject to review by the
geotechnical consultant. Clean granular backfill and/or bedding are not recommended in slope
areas.
Section 9 -Drainage
Where deemed appropriate by the geotechnical consultant, canyon subdrain systems should be
installed in accordance with CTE's recommendations during grading.
Typical subdrains for compacted fill buttresses, slope stabilization or sidehill masses, should be
installed in accordance with the specifications.
STANDARD SPECIFICATIONS OF GRADING
Page 8 of 26
AppendixD Page D-9
Standard Specifications for Grading
Roof, pad and slope drainage should be directed away from slopes and areas of structures to
suitable disposal areas via non-erodible devices (i.e., gutters, downspouts, and concrete swales ).
For drainage in extensively landscaped areas near structures, (i.e., within four feet) a minimum
of 5 percent gradient away from the structure should be maintained. Pad drainage of at least 2
percent should be maintained over the remainder of the site.
Drainage patterns established at the time of fine grading should be maintained throughout the life
of the project. Property owners should be made aware that altering drainage patterns could be
detrimental to slope stability and foundation performance.
Section IO -Slope Maintenance
IO.I -Landscape Plants
To enhance surficial slope stability, slope planting should be accomplished at the
completion of grading. Slope planting should consist of deep-rooting vegetation
requiring little watering. Plants native to the southern California area and plants relative
to native plants are generally desirable. Plants native to other semi-arid and arid areas
may also be appropriate. A Landscape Architect should be the best party to consult
regarding actual types of plants and planting configuration.
10.2 -Irrigation
Irrigation pipes should be anchored to slope faces, not placed in trenches excavated into
slope faces.
Slope irrigation should be minimized. If automatic timing devices are utilized on
irrigation systems, provisions should be made for interrupting normal irrigation during
periods of rainfall.
10.3 -Repair
As a precautionary measure, plastic sheeting should be readily available, or kept on hand,
to protect all slope areas from saturation by periods of heavy or prolonged rainfall. This
measure is strongly recommended, beginning with the period prior to landscape planting.
If slope failures occur, the geotechnical consultant should be contacted for a field review
of site conditions and development of recommendations for evaluation and repair.
If slope failures occur as a result of exposure to period of heavy rainfall, the failure areas
and currently unaffected areas should be covered with plastic sheeting to protect against
additional saturation.
STANDARD SPECIFICATIONS OF GRADING
Page 9 of 26
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Appendix D Page D-10
Standard Specifications for Grading
In the accompanying Standard Details, appropriate repair procedures are illustrated for
superficial slope failures (i.e., occurring typically within the outer one foot to three feet of
a slope face).
ST AN DARO SPECIFICATIONS OF GRADING
Page 10 of 26
FINISH CUT
SLOPE
---------
5'MIN
BENCHING FILL OVER NATURAL
FILL SLOPE
SURFACE OF FIRM
EARTH MATERIAL
--
10'
TYPICAL
15' MIN. (INCLINED 2% MIN. INTO SLOPE)
BENCHING FILL OVER CUT
FINISH FILL SLOPE
SURFACE OF FIRM
EARTH MATERIAL
10'
TYPICAL
15' MIN OR STABILITY EQUIVALENT PER SOIL
ENGINEERING (INCLINED 2% MIN. INTO SLOPE)
NOT TO SCALE
------
BENCHING FOR COMPACTED FILL DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 11 of 26
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MINIMUM
DOWNSLOPE
KEY DEPTH
TOE OF SLOPE SHOWN
ON GRADING PLAN
FILL -----------------------~~--
--<..P\~\.. ----~\vp. ------<-~~~,\-\ ~ ----
-".'c>\..'y ---5D\'r ---\)~ -~------------1
.,.... ---1 O' TYPICAL BENCH
/ ---WIDTH VARIES
.111 ---/f' --/ --(-.--
2% MIN ---
15' MINIMUM BASE KEY WIDTH
COMPETENT EARTH
MATERIAL
TYPICAL BENCH
HEIGHT
PROVIDE BACKDRAIN AS REQUIRED
PER RECOMMENDATIONS OF SOILS
ENGINEER DURING GRADING
WHERE NATURAL SLOPE GRADIENT IS 5:1 OR LESS,
BENCHING IS NOT NECESSARY. FILL IS NOT TO BE
PLACED ON COMPRESSIBLE OR UNSUITABLE MATERIAL.
NOT TO SCALE
4'
FILL SLOPE ABOVE NATURAL GROUND DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 12 of 26
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REMOVE ALL TOPSOIL, COLLUVIUM,
AND CREEP MATERIAL FROM
TRANSITION
CUT/FILL CONTACT SHOWN
ON GRADING PLAN
CUT/FILL CONTACT SHOWN
ON "AS-BUILT"
NATURAL~ --TOPOGRAPHY ---------------CUT SLOPE*
-----------
FILL ----- - --?-'i=-wio\1'2-
-----;\_~;\)Ii' p.1'10 ~<;:_?:...-- - -
,o?so\\.., c - - -... I , ---! ---4' TYPICAL
15' MINIMUM
NOT TO SCALE
10' TYPICAL
BEDROCK OR APPROVED
FOUNDATION MATERIAL
*NOTE: CUT SLOPE PORTION SHOULD BE
MADE PRIOR TO PLACEMENT OF FILL
FILL SLOPE ABOVE CUT SLOPE DETAIL
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COMPETENT
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--~-------------~ -..... ' /,..
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TYPICAL BENCHING
SEE DETAIL BELOW
MINIMUM 9 FT3 PER LINEAR FOOT
OF APPROVED FILTER MATERIAL
CAL TRANS CLASS 2 PERMEABLE MATERIAL
FILTER MATERIAL TO MEET FOLLOWING
SPECIFICATION OR APPROVED EQUAL:
,_.,,,, A--""'
' / REMOVE UNSUITABLE
DETAIL
14"
MINIMUM
MATERIAL
INCLINE TOWARD DRAIN
AT 2% GRADIENT MINIMUM
MINIMUM 4" DIAMETER APPROVED
PERFORATED PIPE (PERFORATIONS
DOWN)
6" FILTER MATERIAL BEDDING
SIEVE SIZE PERCENTAGE PASSING
APPROVED PIPE TO BE SCHEDULE 40
POLY-VINYL-CHLORIDE (P.V.C.) OR
APPROVED EQUAL. MINIMUM CRUSH
STRENGTH 1000 psi
1"
N0.4
N0.8
N0.30
NO. 50
NO. 200
100
90-100
40-100
25-40
18-33
5-15
0-7
0-3
PIPE DIAMETER TO MEET THE
FOLLOWING CRITERIA, SUBJECT TO
FIELD REVIEW BASED ON ACTUAL
GEOTECHNICAL CONDITIONS
ENCOUNTERED DURING GRADING
LENGTH OF RUN PIPE DIAMETER
INITIAL 500' 4"
500' TO 1500' 6"
> 1500' 8"
NOT TO SCALE
TYPICAL CANYON SUBDRAIN DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 14 of 26
CANYON SUBDRAIN DETAILS
TYPICAL BENCHING
SEE DETAILS BELOW
TRENCH DETAILS
6" MINIMUM OVERLAP
INCLINE TOWARD DRAIN
AT 2% GRADIENT MINIMUM
OPTIONAL V-DITCH DETAIL MINIMUM 9 FT3 PER LINEAR FOOT
OF APPROVED DRAIN MATERIAL
MIRAFI 140N FABRIC
OR APPROVED EQUAL MIRAFI 140N FABRIC
OR APPROVED EQUAL
MINIMUM
0
24"
MINIMUM
MINIMUM 9 FT3 PER LINEAR FOOT
OF APPROVED DRAIN MATERIAL
60° TO 90°
APPROVED PIPE TO BE
SCHEDULE 40 POLY-
VINYLCHLORIDE (P.V.C.)
OR APPROVED EQUAL.
MINIMUM CRUSH STRENGTH
1000 PSI.
DRAIN MATERIAL TO MEET FOLLOWING
SPECIFICATION OR APPROVED EQUAL:
PIPE DIAMETER TO MEET THE
FOLLOWING CRITERIA, SUBJECT TO
FIELD REVIEW BASED ON ACTUAL
GEOTECHNICAL CONDITIONS
ENCOUNTERED DURING GRADING
SIEVE SIZE
1 Y:t
1"
%"
%"
NO. 200
PERCENTAGE PASSING
88-100 LENGTH OF RUN
5-40
INITIAL 500'
0-17 500' TO 1500'
0-7 > 1500'
0-3
NOT TO SCALE
GEOFABRIC SUBDRAIN
STANDARD SPECIFICATIONS FOR GRADING
Page 15 of 26
PIPE DIAMETER
4"
6"
8"
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FRONT VIEW
r
-· . -'• -'• -·-·-~. CONCRETE '·~ · '·~ · '·~ · '·~ · '·~ · '·~ · J 6" Min
CUT-OFF WALL----:-/·:~; t<:?!·~ \:/~~-:;:~~-: .
~~\-!-~.,.~ . , .. ·......,·-~
SUBDRAIN PIPE .----• · -• ·, -• ·, -•·,-• ·' • • 6" Min. _.........._.. ' • ' ,. • ' A. ' ,p,. ' ~. ' _L
·!. -. ! . -. ! .-. !-: . ~. . ! . .
24"Min. -~
6"Min .
SIDE VIEW
~ 12" Min.~ 6" Min.
CONCRETE --r
CUT-OFF WALL----·:.._-,·;,\· J 6" Min.
NOT TO SCALE
RECOMMENDED SUBDRAIN CUT-OFF WALL
STANDARD SPECIFICATIONS FOR GRADING
Page 16 of 26
FRONT VIEW
SUBDRAIN OUTLET
PIPE (MINIMUM 4" DIAMETER)
SIDE VIEW
ALL BACKFILL SHOULD BE COMPACTED
IN CONFORMANCE WITH PROJECT
SPECIFICATIONS. COMPACTION EFFORT
SHOULD NOT DAMAGE STRUCTURE
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t> -, E> -,. t> -,. ' . b. . ' . b.. • ' • b. .
.6.,,A,,~.,
t>. -,. E>. -" t> .-,. ,, b. . •' b.. . ' b. .
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-'V'. -'O' • -V' •
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,, . b. . •' . b.. • 1' . b,. .
.0. ' .0. ' ..0.
24" Min.
24"Min.
NOTE: HEADWALL SHOULD OUTLET AT TOE OF SLOPE
OR INTO CONTROLLED SURFACE DRAINAGE DEVICE
ALL DISCHARGE SHOULD BE CONTROLLED
THIS DETAIL IS A MINIMUM DESIGN AND MAY BE
MODIFIED DEPENDING UPON ENCOUNTERED
CONDITIONS AND LOCAL REQUIREMENTS
NOT TO SCALE
24" Mfn.
12"
TYPICAL SUBDRAIN OUTLET HEADWALL DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 17 of 26
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4" DIAMETER PERFORATED
PIPE BACKDRAIN
4" DIAMETER NON-PERFORATED
PIPE LATERAL DRAIN
SLOPE PER PLAN
FILTER MATERIAL
15' MINIMUM
BENCHING
AN ADDITIONAL BACKDRAIN
AT MID-SLOPE WILL BE REQUIRED FOR
SLOPE IN EXCESS OF 40 FEET HIGH.
KEY-DIMENSION PER SOILS ENGINEER
(GENERALLY 1/2 SLOPE HEIGHT, 15' MINIMUM)
DIMENSIONS ARE MINIMUM RECOMMENDED
NOT TO SCALE
TYPICAL SLOPE STABILIZATION FILL DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 18 of 26
4" DIAMETER PERFORATED
PIPE BACKDRAIN
4" DIAMETER NON-PERFORATED
PIPE LATERAL DRAIN
SLOPE PER PLAN
FILTER MATERIAL
15' MINIMUM
BENCHING
H/2
ADDITIONAL BACKDRAIN AT
MID-SLOPE WILL BE REQUIRED
FOR SLOPE IN EXCESS OF 40
FEET HIGH.
KEY-DIMENSION PER SOILS ENGINEER
DIMENSIONS ARE MINIMUM RECOMMENDED
NOT TO SCALE
TYPICAL BUTTRESS FILL DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 19 of 26
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FINAL LIMIT OF
EXCAVATION
OVEREXCAVATE
OVERBURDEN
(CREEP-PRONE)
DAYLIGHT
LINE
OVEREXCAVATE 3'
AND REPLACE WITH
COMPACTED FILL
COMPETENT BEDROCK
TYPICAL BENCHING
LOCATION OF BACKDRAIN AND
OUTLETS PER SOILS ENGINEER
AND/OR ENGINEERING GEOLOGIST
DURING GRADING. MINIMUM 2%
FLOW GRADIENT TO DISCHARGE
LOCATION.
EQUIPMENT WIDTH (MINIMUM 15')
NOTTO SCALE
DAYLIGHT SHEAR KEY DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 20 of 26
PROPOSED GRADING
BASE WIDTH "W" DETERMINED
BY SOILS ENGINEER
NATURAL GROUND
COMPACTED FILL
NOT TO SCALE
PROVIDE BACKDRAIN, PER
BACKDRAIN DETAIL. AN
ADDITIONAL BACKDRAIN
AT MID-SLOPE WILL BE
REQUIRED FOR BACK
SLOPES IN EXCESS OF
40 FEET HIGH. LOCATIONS
OF BACKDRAINS AND OUTLETS
PER SOILS ENGINEER AND/OR
ENGINEERING GEOLOGIST
DURING GRADING. MINIMUM 2%
FLOW GRADIENT TO DISCHARGE
LOCATION.
TYPICAL SHEAR KEY DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 21 of 26
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FINISH SURFACE SLOPE
3 FP MINIMUM PER LINEAR FOOT
APPROVED FILTER ROCK*
CONCRETE COLLAR
PLACED NEAT
A
2.0% MINIMUM GRADIENT
A
4" MINIMUM DIAMETER
SOLID OUTLET PIPE
SPACED PER SOIL
ENGINEER REQUIREMENTS
COMPACTED FILL
4" MINIMUM APPROVED
PERFORATED PIPE**
(PERFORATIONS DOWN)
MINIMUM 2% GRADIENT
TO OUTLET
DURING GRADING TYPICAL BENCH INCLINED
TOWARD DRAIN
**APPROVED PIPE TYPE:
MINIMUM
12" COVER
SCHEDULE 40 POLYVINYL CHLORIDE
(P.V.C.) OR APPROVED EQUAL.
MINIMUM CRUSH STRENGTH 1000 PSI
BENCHING
DETAIL A-A
12"
TEMPORARY FILL LEVEL
MINIMUM 4" DIAMETER APPROVED
SOLID OUTLET PIPE
MINIMUM
*FILTER ROCK TO MEET FOLLOWING
SPECIFICATIONS OR APPROVED EQUAL:
SIEVE SIZE
1"
%"
%"
N0.4
NO. 30
NO. 50
NO. 200
PERCENTAGE PASSING
100
90-100
40-100
25-40
5-15
0-7
0-3
NOT TO SCALE
TYPICAL BACKDRAIN DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 22 of 26
FINISH SURFACE SLOPE
MINIMUM 3 FP PER LINEAR FOOT
OPEN GRADED AGGREGATE*
TAPE AND SEAL AT COVER
CONCRETE COLLAR
PLACED NEAT COMPACTED FILL
A
2.0% MINIMUM GRADIENT
A
MINIMUM 4" DIAMETER
SOLID OUTLET PIPE
SPACED PER SOIL
ENGINEER REQUIREMENTS
MINIMUM
12" COVER
*NOTE: AGGREGATE TO MEET FOLLOWING
SPECIFICATIONS OR APPROVED EQUAL:
SIEVE SIZE PERCENTAGE PASSING
1 Y,,n 100
1" 5-40
%" 0-17
%" 0-7
NO. 200 0-3
TYPICAL
BENCHING
DETAIL A-A
12"
MINIMUM
NOT TO SCALE
MIRAFI 140N FABRIC OR
APPROVED EQUAL
4" MINIMUM APPROVED
PERFORATED PIPE
(PERFORATIONS DOWN)
MINIMUM 2% GRADIENT
TO OUTLET
BENCH INCLINED
TOWARD DRAIN
TEMPORARY FILL LEVEL
MINIMUM 4" DIAMETER APPROVED
SOLID OUTLET PIPE
BACKDRAIN DETAIL (GEOFRABIC)
STANDARD SPECIFICATIONS FOR GRADING
Page 23 of 26
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SOIL SHALL BE PUSHED OVER
ROCKS AND FLOODED INTO
VOIDS. COMPACT AROUND
AND OVER EACH WINDROW.
1
STACK BOULDERS END TO END.
DO NOT PILE UPON EACH OTHER.
NOT TO SCALE
ROCK DISPOSAL DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 24 of 26
STAGGER
ROWS
STREET
10'
5' MINIMUM OR BELOW
DEPTH OF DEEPEST
UTILITY TRENCH
(WHICHEVER GREATER)
FINISHED GRADE BUILDING
0
NO OVERSIZE, AREA FOR
FOUNDATION, UTILITIE~~l
AND SWIMMING POOL~
0 O
~··~
WINDROW~
0
TYPICAL WINDROW DETAIL (EDGE VIEW)
GRANULAR SOIL FLOODED
TO FILL VOIDS
HORIZONTALLY PLACED
COMPACTION FILL
PROFILE VIEW
NOT TO SCALE
ROCK DISPOSAL DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 25 of 26
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GENERAL GRADING RECOMMENDATIONS
CUT LOT
-----TOPSOIL, COLLUVIUM AND _ ---
WEATHERED BEDROCK --
-------
--
--
-----ORIGINAL
GROUND ---
3' MIN
--------UNWEATHERED BEDROCK
OVEREXCAVATE
AND REGRADE
CUT/FILL LOT {TRANSITION)
-COMPACTED FILL -------~-~~--------~ ~ -.,,._ __ ___. TOPSOIL, COLLUVIUM -
_.,AND WEATHERED
BEDROCK -
-----.,--
---UNWEATHERED BEDROCK
NOT TO SCALE
TRANSITION LOT DETAIL
STANDARD SPECIFICATIONS FOR GRADING
Page 26 of 26
__..-: ORIGINAL
____ .,GROUND
'MIN
3' MIN
OVEREXCAVATE
AND REGRADE
APPENDIXE
SITE INSPECTION REPORT BY
SOIL TESTERS 2005
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September 2, 2005
Mike O'Gara
P. 0. Box 1633
Carlsbad, California 92018
Subject: File No. 1106F3-05
SITE INSPECTION
Proposed Residential Building Site
3980 Highland Avenue
City of Carlsbad
Dear Mr. O'Gara:
SCOPE
P.O. Box 1195
Lakeside, California
92040
(619) 443-0060
Jn accordance with your request, a Site Inspection has been perfurmed at the ~ect site. The
purpose of this investigation was to examine existing site conditions and provide engineering
recommendations for the five, proposed two--story over basement, single-family residential
structures.
FIELD JNSPECTION
In order to accomplish this purpose, a representative of this firm visited the site, reviewed the
topography and site conditions and visually and textually classified the surface and near surface
soils. Representative samples of the on-site soils were obtained from three test explorations
approximately four to fifteen feet in depth and tested for density, shear strength and expansive
characteristics.
SITE CONDmONS
The suiject site is a residential parcel located on the easterly side of Highland Drive. The
property is located at the top of a rise with the east side of the property fronting James Drive
approximately 15 to 20 feet lower1han the west side. A 10-foot, 2:1 cut slope extends midway
through the site from the south to north. A 2 to 3 feet fill slope is located at the top of the cut on
the north end. The property is presently occupied by a one-story singte-&mily residence with
detached garage. There is a four-foot retaining wall behind the garage and a 3-foot rock
retaining wall behind the house. Adjacent properties are occupied by residential structures.
1
MikeO'Gara File No. 1106F3-05 September 2, 2005
Man-made fill soils were encountered to a depth of approximately one to three feet during the
course of this inspection; however, native soils were loose and compressI'ble to approximately 15
feet in depth.
son. CONDIDONS
Soils encountered in Test Exploration No. 3 at the high.er elevation off Highland Drive were
generally finn · to medium dense, cemented, red brown silty sands becoming more dense with
depth to the bottom of the excavation, approximately four feet in depth. Test Explorations Nos.
1 and 2 were located below the cut at the lower elevation off James Drive. Soils encountered in
these explorations were generally loose to finn gramdar sands to 10 to 15 feet in depth. Dense
formational soils were not encountered at the lower elevation. None of the soils we encountered
were considered to be detrimentally expansive with respect to change in volume with change in
moisture content.
CONCLUSIONS AND RECOMMENDATIONS
1.
2.
3.
The loose native soils we encountered at the lower elevations should not be utilized to
support the proposed new structures. In order to provide adequate support, the loose
soils should be removed to at least five feet below the lowest footing and the bottom of
the excavation compacted using a vibratory compacter. The bottom of the
excavation should be tested to insure that compaction is at least 90 percent of
maximum dry density. The soils may then be replaced and recompacted to at least
90 percent of maximum dry density in accordance with the Grading Specifications in
ttlis report. The recompaction should extend at least 5 feet outside the proposed
building footprint. Any deleterious material that may be encountered should be
removed prior to recompaction.
We anticipate that basement excavations for the structures located in the higher
elevations will achieve suitable soils for adequate support. The basement excavations
should be inspected by a representative of this firm to insure that proper soil strata have
been achieved.
No special foundation design to resist expansive soil is necessary. Conventional spread
footings founded a minimum of 12 inches below lowest adjacent grade and having a
width detennined by the allowable soil bearing value as detailed above may be used for
foundation support. Footing widths should be at least 12 inches for continuous footings
and 24 inches for square footings due to practical considerations as well as Building
Code requirements. These recommendations are based upon the soil type only and
do not take into consideration structural requirements.
2
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MikeO'Gara FileNo. 1106F3-05 September 2, 2005
4.
5.
6.
7.
Reinforcing in footings should consist of at least one #4 steel bar placed continuously in
the top and bottom of continuous footings regardless of stru.ctural requirements.
Reinforcing for isolated footings are dictated by the structural requirements. These
recommendations are based upon the soil type encounttftd and do not take into
consideration the proposed bearing load.
Concrete slabs-on-grade should be constructed to have a nominal thickness of 4• and
underlain with a sand blanket of 3 inches in thickness. Provide minimum temperature
reinforcement consisting of 6X6-10/10 welded wire mesh. The sand subbase (sand
blanket) should have a sand equivalent exceeding 30 per ASTM D2419. All slabs
should either have a conventional thickened edge or be poured monolithically with
continuous footings at the slabs perimeter. Conventional thickened edges should be 8"
thick at slab ed~ uniformly tapering to 4n thick at X from slab edge. The thickened
edges or monolithic footings should extend completely around the slab's perimeter.
Construction and expansion joints should be considered slab edges. Maximum spacing
of expansion joints is 50' for interior slabs and 30' for exterior slabs.
A representative sample of the foundation soil was remolded to 9()0A, of maximum
dry density. Based on the following test results, a safe allowable bearing value of at
least 2500 pounds per square foot for 12 inch deep footings may be used in
designing the foundations and slab for the proposed structures. This value may be
increased by one third for wind and/or seismic loading.
Soil Description
Depth of Sample
Angle of internal friction
Cohesion
Unit weight
Maximum Dry Density
Optimum Moisture Content
Expansion Index
Red brown silty sand
3'
39°
243 psf
121.0 pcf
133.4 pcf
8.5%
31
Resistance to horizontal movement may be provided by allowable soil passive pressure
and/or coefficient of fiiction of concrete to soil. The allowable passive pressure may be
assumed to be 500 psf at the surface and increasing at the rate of 500 psf per foot of
depth. These pressures assume a :fiictionless vertical element, no surcharge and level
adjacent grade. If these assumptions are incorrect, we should be contacted for values
that reflect the true conditions. The values are for static conditions and may be increased
1/3 for wind and/or seismic loading. The coefficient of friction of concrete to soil may
be safely assumed to be O .5.
3
MikeO'Gara File No. 1106F3-05 September 2, 2005
8. Active pressures for the design of unrestrained, cantilevered, individually supported
retaining walls capable of slight movement away from load may be considered to be
equivalent to the pressures developed by a fluid with a density of30 pcf This value
assumes a vertical, smooth wall and level drained backfill. We should be contacted
for new pressures if these assumptions are incorrect. Restrained walls, incapable of
movement away from load without damage such as basement walls, should be
designed for the additional equivalent fluid of 24 pcf applied triangularly for
cohesionless type soils and trapezoidally for cohesive type soils.
The above design values and foundation design assume that the basement wall
excavations will expose soils similar to those we tested during our site
inspection. We should inspect the cut to insure that the soils exposed are the
same as those we tested.
For any grading proposed or contemplated for this project, the following grading specifications
should be utilized.
RECOMMENDED GRADING SPECIFICATIONS
Proposed Residential Building Site
3980 ffighland Avenue
City of Carlsbad
GENERAL: Soil Testers and · Soil Engineer' are synonymous hereinafter and shall be
employed to inspect and test earthwork in accordance with these specifications, the accepted
plans, and the requirements of any jurisdictive governmental agencies. They are to be allowed
adequate access so that the inspections and tests may be perfmmed. The Soil Engineer shall be
apprised of schedules and any unforeseen soil conditions.
Substandard conditions or worlcrnanship, inadequate compaction, adverse weather, or deviation
from the lines and grades shown on the plans, etc., shall be cause for the soil engineer to either
stop construction until the conditions are corrected or recommend rejection of the work Refusal
to comply with these specifications or the recommendations and/or interpretations of the soil
engineer will be cause for the soil engineer and/or his representative to immediately terminate his
services.
Deviations from the recommendations of the Soil Report, from the plans, or from these
Specifications must be approved in writing by the owner and the contractor and endorsed by the
soil engineer.
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SOIL TEST METHODS:
Maximum Density & Opt Moisture
Density of Soil In-Place
Soil Expansion
Shear Strength
Gradation & Grain Size
File No. 1106F3-05 September 2, 2005
-ASTMD1557-70
--ASTM Dl556, D2922 and D3017
-UBC STANDARD 29-2
--ASTMD3080-72
-ASTMD1140-71
--ASTM D2325-68 Capillary Moisture Tension
Organic Content -% Weight loss after heating for 24 hours
at 300° F and after deducting soil moisture.
LIMITING SOIL CONDIDONS:
Minimum Compaction 900/o for 'disturbed' soils. (Existing fill,
newly placed fill, plowed ground, etc.)
84% for natural, undisturbed soils.
Expansive Soils
Insufficient fines
Oversized Particles
95% for pavement subgrade within'}; of
finish grade and pavement base course.
Expansion index exceeding 20
Less than 40% passing the #4 sieve.
Rocks over 10" in diameter.
PREPARATION OF AREAS TO RECEIVE FILL:
Brush, trash, debris and detrimental soils shall be cleared from the areas to receive fill.
Detrimental soils shall be removed to £inn competent soil. Slopes exceeding 200/o should be
stepped uphill with benches 10' or greater in width. Scarify area to receive fill to 6n depth and
compact .
. FHL MATERIAL shall not contain insufficient fines, oversized particles, or excessive
organics. On-site disposition of oversized rock or expansive soils is to be at the written direction
of the Soil Engineer. Select fill shall be as specified by the soil engineer. At) fills shall he
compacted and tested.
SUBDRAJNS shall be installed if required by and as directed by and detailed by the soil
engineer and shall be left operable and unobstructed. They shall consist of 3" plastic perforated
pipe set in a minimum cover of 4" of :filter rock in a 'vee' ditch to intercept and drain free ground
from the mass fills. Perforated pipe shall be schedule 40, Poly-Vmyl-Chloride or Acrylonitrile
Butadienne Styrene plastic. Rock filter material shall conform to the following gradation:
Sieve size:
%Passing:
3/4"
90-100
#4
25-50
,5
#30
5-20
#200
0-7
MikeO'Gara File No. 1106F3-05 September 2, 2005
Subdrains shall be set at a minimum gradient of 0.2% to drain by gravity and shall be tested by
dye flushing before acceptance. Drains found inoperable shall be excavated and replaced.
CAPPING EXPANSIVE SOilS: If capping expansive soils with non-expansive soil to
mitigate the expansive potential is used, the cap should be compacted, non-expansive, select soil
placed for a minimum thickness 3' over the expansive soil and for a minimum distance of 8'
beyond the exterior perimeter of the structure. Special precautions should be taken to ensure that
the non-expansive soil remains uncontaminated and the minimum thickness and dimensions
around the structure are maintained. The expansive soils underlying the cap of non-expansive
cap should be pre-saturated to a depth of 3' to obtain a degree saturation exceeding 90% before
any construction supported by the compacted cap.
The non-expansive soil comprising the cap should confonn to the following:
Minimum Compaction
Maximum Expansion Index
Minimum Angle of Internal Friction
Cohesion Intercept
90%
30
33Deg
IOOpsf
UNFORESEEN CONDIDONS: Soil Testers assume no responsibility for conditions, which
differ from those, described in the applicable current reports and documents for this property.
Upon termination of the soil engineer's services for any reason, his fees up to the time of
termination become due and payable. If it is necessary for the soil engineer to issue an
unfavorable report concerning the work that he has been hired to test and inspect, the soil
engineer shall not be held liable for any damages that might result from his 'unfavorable report'.
If we can be of any further assistance, please do not hesitate to contact our office. This
opportunity to be of service is sincerely appreciated.
Respectfully submitted,
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LOCATION OF
EXPLORATION TRENCHES
1:.1 EXPLORATION TRENCH
11421 Woodside Ave., Suite C
Santee, California 92-071
(619) 562-0500
MikeO'Gara
Plate No. 2
EXPLORATION NUMBER l
Date Logged:
Date Reported:
6/28/05
9/02/05
D h U . tied Cl ifi . ept ntl ass cations
Oto6' SM Red brown,
6to 15' SM Red brown,
File No. 1106F3-05 September 2, 2005
S "lD 01
humid, loose,
humid, firm,
Equipment Used:
Groundwater:
Refusal:
escnptton
Backhoe
Not Encountered
Not Encountered
S i1 T 0 iype
SIL TY SAND with clay binder 1
(Native)
SJL TY SAND with clay binder 1
(Native)
Darker brown, wet, firm, SIL TY SAND
Limit of Equipment
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Plate No. 3
EXPLORATION NUMBER 2
Date Logged:
Date Reported:
6/28/05
9/02/05
ept Um 1e Cass D h ·r. d ifi cations
Oto 10' SM Red brown,
SILTY SAND
10 to 11' SM Tan moist,
File No. 1106F3-05
Equipment Used:
Groundwater:
Refusal:
·10 Sot escnption
moist, firm to medium dense,
loose, cemented, granular,
Bottom of trench
September 2, 2005
Backhoe
Not Encountered
Not Encountered s· oil Type
cemented, 1
(Native)
SILTY SAND
<Native)
MikeO'Gara
Plate No. 4
EXPLORATION NUMBER 3
Date Logged:
Date Reported:
D h U "fled Cl ,ept m1
Oto4' SM
6/28/05
9/02/05
ifi ti ass ca ons
Red brown,
File No. 1106F3-05
Equipment Used:
Groundwater:
Refusal:
S ilD . f 0 escnp: 10n
September 2, 2005
Backhoe
Not Encountered
Not Encountered
S ii T 0 ype
humid, medium dense, SILTY SAND l
(Native)
bottom of trench
SOIL TEST RESULTS ON REMOLDED SAMPLES .------REMOLDED SPECIMENS----, '
rSoi!!r~on
I Sample Tested
I General Description
V V V V
Id Clsf V Color Texture
1 SM T1@3" Red brown SIL TY SAND
Maximur Density (pcf) Optimum Moistu I S'iific
V V V
Ymx OMc Gs
133.4 8.5 2.65
Density (pcf)
J Compaction Friction (deg)
ravity I Moisture I Cohesion (psf)
Expansio lnde)1 I Saturation I
Y Y V V V V V
El Yd Re We Os Fr C
20 121.4 91% 6.4% 75% 39 243
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