HomeMy WebLinkAboutMS 01-17; BRISTOL COVE; GEOTECHNICAL INVESTIGATION; 2001-10-16I
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Leighton and Associates
GEOTECHNICAL CONSULTANTS
GEOTECHNICAL INVESTIGATION
FOR THE PROPOSED DEVELOPMENT OF
LOT 13 OF MAP NO. 5162, COVE DRIVE,
CARLSBAD, CALIFORNIA
October 16, 2001
Project No. 040437-001
Prepared For:
BRISTOL COVE, LLC
2880 Pio Pico Drive
Carlsbad, California 92008
0/-/7
3934 Murphy Canyon Road, #8205, San Diego, CA 92123-4425
(858) 292-8030 • FAX (858) 292-0771 • www.leightongeo.com
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A GTG Company GEOTECHNICAL
August 12, 2002
To:
Attention:
Subject:
References:
Bristol Cove, LLC
2880 Pio Pico Drive
Carlsbad, California, 92008
Mr. Steve Lappin
Project No. 040437-001
Addendum to Geotechnical Investigation, Foundation Recommendations, Lot 13 of Map
No. 5162, Cove Drive, Carlsbad, California
Leighton and Associates, Inc., 2001, Geotechnical Investigation for the Proposed
Development of Lot 13 of Map No. 5162, Cove Drive, Carlsbad, California, Project No.
040437-001, dated October 16, 2001
In accordance with your request, this addendum addresses conventional foundation recommendations for
the proposed residential development at Lot 13 of Map No. 5162, located on the north side of Cove Drive
in Carlsbad, California. We anticipate the residential structure will be three-stories in height with a concrete
slab-on-grade foundation and wood and stucco construction. It should be noted that our analysis performed
for the geotechnical investigation indicated that the artificial older fill soils are compressible in their present
state and will require removal and recompaction within areas of the proposed development (Leighton,
2001). The depth of the unsuitable material removal is estimated to be on the order of approximately 4 to 10
feet in depth below the existing ground surface.
Foundation Design -Residential
Footings bearing in properly compacted fill soils with a very low to low expansion potential should extend a
minimum of 24 inches below the lowest adjacent soil grade for a three-story structure. At this depth,
footings may be designed using an allowable-soil bearing value of 2, 000 pounds per square foot. This value
may be increased by one-third for loads of short duration including wind or seismic forces. Continuous
footings should have a minimum width of 18 inches, and should be reinforced by placing at least two No.4
rebar near the top and two No.4 rebar near the bottom of the footing, and in accordance with the structural
engineer's requirement. Isolated-spread footings should have a minimum width of 24 inches. A grade
beam reinforced with two No.4 rebars top and bottom should be placed at the garage door opening. Garage
slabs should be isolated from stemwall footings by 3/8-inch felt and quarter-sawn.
Floor Slab Design -Residential
All slabs should have a minimum thickness of 5 inches and be reinforced at slab midheight with No. 3
rebars at 18 inches on center (each way) or No.4 rebars at 24 inches center (each way). Additional
reinforcement andlor concrete thickness to accommodate specific loading conditions or anticipated
settlement should be evaluated by the structural engineer based on a modulus of sub grade reaction of 100
3934 Murphy Canyon Road, #8205, San Diego, CA 92123-4425
(858) 292-8030 • FAX (858) 292-0771 • www.leightongeo.com
040437-001
kips per cubic foot. We emphasize that is the responsibility of the contractor to ensure that the slab
reinforcement is placed at midheightofthe slab.
Slabs should be underlain by a 2-inch layer of clean sand (S.B. greater than 30) to aid in concrete curing,
which is underlain by a 1 O-mil (or heavier) moisture barrier, which is, in tum, underlain by a 2-inch layer of
clean sand to act as a capillary break. All penetrations and laps in the moisture barrier should be
appropriately sealed. The spacing of crack-control joints should be designed by the structural engineer.
Sawcuts should be made within 24 hours of concrete placement. Our experience indicates that use of
reinforcement in slabs and foundations will generally reduce the potential for drying and shrinkage
cracking. However, some cracking should be expected as the concrete cures. Minor cracking is considered
normal; however, it is often aggravated by a high cement ratio, high concrete temperature at the time of
placement, small nominal aggregate size and rapid moisture loose due to hot, dry, and/or windy weather
conditions during placement and curing. Cracking due to temperature and moisture fluctuations can also be
expected. The use of low slump concrete (not exceeding 4 inches at the time of placement) can reduce the
potential for shrinkage cracking.
Moisture barriers can retard, but not eliminate moisture vapor movement from the underlying soils up
through the slab. We recommend that the floor covering installer test the moisture vapor flux rate prior to
attempting application of the flooring. "Breathable" floor coverings should be considered if the vapor flux
rates are high. A slip sheet should be used if crack sensitive floor coverings are planned.
If you have any questions regarding this letter, please contact this office. We apprec~ate this opportunity to
be of service.
Distribution: (3) Addressee
(3) Mr. Leo Fitzsimon, PE
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Respectfully submitted,
LEIGHTON AND ASSOCIATES,INC.
vdL-o.cJL
William D. Olson, RCE 45283
Senior Project Engineer
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Leighton and Associates
1961 -2001
To: Bristol Cove, LLC
2880 Pio Pico Drive
Carlsbad, California, 92008
GEOTECHNICAL CONSULTANTS
October 16, 2001
Project No. 040437·001
Subject: Geotechnical Investigation for the Proposed Development of Lot 13 of Map No. 5162,
Cove Drive, Carlsbad, California
In accordance with your request, we have performed a preliminary geotechnical investigation for the
proposed development for Lot 13 of Map No. 5162, located on the north side of Cove Drive in Carlsbad,
California. The purpose of our investigation was to evaluate the existing site geotechnical conditions and
provide geotechnical conclusions and recommendations relative to the proposed development of the site.
This report presents the results of our subsurface investigation and geotechnical analysis, review of
available geotechnical and geologic reports and maps applicable to the general vicinity of the property, and
provides a summary of our conclusions and recommendations.
Based on the results of our investigation and review of the geologic and geotechnical reports pertinent to the
site, the proposed development is considered feasible from a geotechnical standpoint provided the
recommendations summarized in this report are implemented during site grading and construction.
If you have any questions regarding our report, please contact this office. We appreciate this opportunity to
be of service.
Respectfully submitted,
LEIGHTON AND ASSOCIATES, INC.
William D. Olson, RCE 45283
Senior Project Engineer
Distribution: (8) Addressee
3934 Murphy Canyon Road, #8205, San Diego, CA 92123-4425
(858) 292-8030 • FAX (858) 292-0771 • www.leightongeo.com
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040495-001
TABLE OF CONTENTS
Section
1.0 IN"TRODUCTION ................................................................................................................................................. 1
1.1 PURPOSE AND SCOPE OF SERVICES .................................................................................................................. 1
1.2 SITE DESCRIPTION AND PROPOSED DEVELOPMENT ........................................................................................... 3
1.3 SURFACE INVESTIGATION AND LABORATORY TESTING ..................................................................................... 3
2.0 GEOTECHNICAL CONDITIONS ...................................................................................................................... 5
2.1 SITE GEOLOGy ................................................................................................................................................. 5
2.2.1 Artificial Older Fill Soils (Map Symbols Afo) ........................................................................................ 5
2.2.2 Santiago Formation (Map Symbol-Tsa) ................................................................................................ 5
2.3 GEOLOGIC STRUCTURE ................................................................................................................................... 5
2.4 GROUNDWATER ............................................................................................................................................... 6
2.5 FAULTING ........................................................................................................................................................ 6
2.6 SEISMJC CONSIDERATIONS ................................................................................................................................ 6
2.6.1 Uniform Building Code Seismic Parameters .......................................................................................... 7
2.7 ENGINEERING CHARACTERISTICS OF ON-SITE SOILS .......................................................................................... 7
2. 7.1 Expansion Potential .............................................................................................................................. 7
2.7.2 Soluble Sulfate Content ......................................................................................................................... 7
3.0 CONCLUSIONS .................................................................................................................................................... 9
4.0 RECOMMENDATIONS ................................................................................................................... ~ ................. 10
4.1 EARTHWORK .................................................................................................................................................. 10
4.1.1 Site Preparation .................................................................................................................................. 10
4.1.2 Removal and Recompaction of Potentially Compressible Soils .......................................................... 10
4.1.3 Excavations ........................................................................................................................................ 10
4.1.4 Fill Placement and Compaction .......................................................................................................... 11
4.2 FOUNDATION DESIGN CONSIDERATIONS ......................................................................................................... 11
4.2.1 Post-Tensioned Foundation Design Considerations ............................................................................. 11
4.2.2 Slab Subgrade Soil Presaturation ........................................................................................................ 13
4.2.3 Seismic Design Parameters .................................................................................................................. 13
4.2.4 Foundation Setback From Slope Faces ............................................................................................... 14
4.3 CEMENT TYPE FOR CONSTRUCTION ................................................................................................................ 14
4.4 LATERAL EARTH PRESSURE AND RETAINING WALL DESIGN ........................................................................... 14
4.5 SURFACE DRAINAGE AND LOTMAlNTENANCE ................................................................................................ 17
4.6 GRADED SLOPES ............................................................................................................................................ 17
4.7 PLAN REVIEW AND CONSTRUCTION OBSERVATION ....................................................................................... 17
5.0 LIMITATIONS ................................................................................................................................................... 18
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TABLE OF CONTENTS (Continued)
FIGURES
FIGURE 1 -SITE LOCATION MAP -PAGE 2
FIGURE 2 -GEOTECHNICAL MAP -PAGE 4
FIGURE 3 -RETAINING WALL BACKFILL AND DRAINAGE DETAIL -PAGE 16
TABLES
TABLE 1 -POST-TENsIONED FOUNDATION DESIGN RECOMMENDATIONS -PAGE 12
TABLE 2 -LATERAL EARTH PRESSURES -PAGE 15
APPENDICES
APPENDIX A -REFERENCES
APPENDIX B -BORING LOGS
APPENDIX C -LABORATORY TEST PROCEDURES AND TEST RESULTS
APPENDIX D -GENERAL EARTHWORK AND GRADING SPECIFICATIONS FOR ROUGH-GRADING
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040495-001
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1.1
040437-001
1.0 INTRODUCTION
Purpose and Scope of Services
This report presents the results of our preliminary geotechnical investigation for Lot 13 of Map
No. 5162, located on the north side of Cove Drive in Carlsbad, California (Figure 1). The purpose of
our preliminary investigation was to evaluate the pertinent geotechnical conditions at the site and to
provide design criteria for the proposed development. The scope of services for our preliminary
geotechnical investigation included the following:
• Review of pertinent geotechnical/geologic documents regarding soil related conditions at the
site (Appendix A).
• Review of available aerial photographs and geologic and topographic maps (Appendix A).
• Excavation and logging of three small-diameter borings to evaluate the existing subsurface
geotechnical conditions. The borings were drilled to a maximum depth of approximately 31
feet, sampled, and logged by a geologist from our fIrm. The borings were backfilled
subsequent to their excavation. Logs of the borings are presented in Appendix B. The
approximate locations of the borings are shown on Figure 2.
• Laboratory testing of representative samples of the onsite soils (Appendix C).
• Geotechnical analysis of the data accumulated.
• Preparation of this geotechnical report presenting the results of our subsurface investigation
and laboratory testing and providing preliminary conclusions and recommendations
(including the General Earthwork and Grading SpecifIcations for Rough Grading presented
as Appendix D) relative to the proposed development of the site. .
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PROJECT
SITE
BAS E MAP: Thomas Bros. GeoFinder for
Windows, San Diego County, 1995, Page 1106
Lot 13 of Map No. 5162
Carlsbad, California
NORTH
1"=2,000'
SITE Project No. 01 040437-001 LOCATION Date
MAP October 2001 Fi-gure No. 1
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1.2
1.3
040437-001
Site Description and Proposed Development
The subject site (Lot 13 of Map No. 5162) which is an irregular shaped property, is located north of
Agua Hedionda Lagoon in the Carlsbad, California (Figure 1). The site is bounded by Cove Drive to
the east, Adams Street to the west, an open space lot to the south and on existing residential structure
to the north. Existing elevations of the site are not known but are anticipated to range from
approximately 15 to 40 feet mean sea level (msl). There are not any known existing improvements
on the site with the exception of the northeast-facing manufactured slope and minor landscaping on
the slope face.
Grading plans or an as-graded geotechnical report were not available for the site, Cove Drive or the
adjacent residential lots. However, we anticipate that Cove Drive and the associated lots were graded
in the 1970's or earlier. Based on our subsurface investigation, fill soils on the order of 5 to 10 feet
are present on the relatively level portion of the site.
Development plans have not been prepared at this time, however, we anticipate grading of the site
will include minor grading and construction of a retaining wall for a single-family residential
structure and associated improvements on the lot. In addition, we anticipate the residential structure
will be two-stories in height with a concrete slab-on-grade foundation and wood and stucco
construction.
Surface Investigation and Laboratory Testing
Our field investigation consisted of the excavation, logging and sampling of three small-diameter
exploratory borings excavated to a maximum depth of approximately 31 feet across the site. Logs of
the borings are presented in Appendix B. The approximate locations of the borings are shown on the
Geotechnical Map (Figure 2). Following the field investigation, the borings were backfilled with
soils from the excavation of the borings.
Limited laboratory testing was performed on representative soil samples of the soils on the site. The
laboratory tests included moisture and density determinations, soluble sulfate content,
hydrocollapse, and expansion index tests. A discussion of the tests performed and a summary of the
results are presented in Appendix C.
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LEGEND
Afo Artiflcial fill -older
Tsa Tertiary Santiago Formation (circled where buned)
'--, Approx. limits of fill (quened where uncertain)
B-3 C. Approx. location of exploratory boring with
TD=16.S' .:; total depth indicated
Tsa
\
o 20 40
L:J L:J Seal e in Feet
GEOTECHNICAL MAP
Lot 13 of Map No. 5162
Carlsbad, California
LOT 12
1.5:1 SLOPE
B-2 TD=16'
~
Project No.
Scale
Engr./Geol.
Drafted By
Date
040437-001
1"=20'
WDO/RKW
KAM
October 2001
Leighton and Associates, Inc.
Afo
OPEN SPACE
C!~~
NORTH
iii
Figure No.2
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2.1
2.3
040437-001
2.0 GEOTECHNICAL CONDITIONS
Site Geology
The subject site is located within the coastal sub-province of the Peninsular Ranges Geomorphic
Province, near the western edge of the southern California batholith. The topography at the edge of
the batholith changes from the rugged landforms developed on the batholith to the more subdued
landforms that typifY the softer sedimentary formations of the coastal plain such as those present on
the site. Specifically, the site is underlain by older artificial fill soils that are considered
undocumented and the Santiago Formation. The approximate areal limits of each of the geologic
units are indicated on the Geotechnical Map (Figure 2). Each of the geologic units present on the site
is described below (youngest to oldest).
2.2.1 Artificial Older Fill Soils (Map Symbols Afo)
Our subsurface investigation indicated that the relatively level portion of the lot consists of
approximately 5 to 10 feet of artificial older fill. No documentation of these fill soils was
available. Consequently, we consider the fill soils to be undocumented and recommend that
the fill soils be removed and recompacted prior to the placement of improvements on the
lot. The fill soils were found to consist of orange-brown, brown and gray-brown, damp to
moist, medium dense silty to clayey sands with minor amounts of stiff sandy clay. These
older fill soils were desiccated and are considered compressible and should be removed to
competent material and recompacted during the development of the site.
2.2.2 Santiago Formation (Map Symbol-Tsa)
The Tertiary-aged Santiago Formation was encountered beneath the fill soils while the
existing northeast-facing slope on the lot is anticipated to also consist of the Santiago
Formation. As encountered during our investigation, the Santiago Formation generally
consisted of mottled gray and light brown, moist to saturated, medium dense to dense, silty
to clayey fine to coarse sandstone.
Geologic Structure
Review of the geologic literature applicable to the site (Appendix A) and our profeSSional
experience on nearby sites with similar soils indicates the on-site formational unit is generally flat
lying and thickly interbedded. Bedding is anticipated to dip generally 5 to 10 degrees or less toward
the west. No faults have been mapped on the site nor were any encountered during our field study.
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040437~OOl
2.4 <JrolUldvvater
<Jround vvater vvas encolUltered in Borings B-1 and B-3 at a depth of approximately 11.5 feet belovv
the existing grolUld surface (or an approximate elevation of 4 feet msl). No surface vvater or seepage
conditions vvere observed on the site. Seasonal fluctuations of surface vvater and ground vvater
should be expected. The grolUld vvater encolUltered on the site is not anticipated to be a constraint to
development provided the recommendations presented herein are implemented during the grading
and construction of the proposed development.
2.5 Faulting
2.6
Our discussion of faults relative to the site is prefaced vvith a discussion of California legislation and
state policies concerning the classification and land-use criteria associated vvith faults. By definition
of the California Mining and Geology Board, an active fault is a fault that has had surface
displacement vvithin Holocene time (about the last 11,000 years). The State Geologist has defined a
potentially active fault as any fault considered to have been. active during Quaternary time (last
1,600,000 years), but that has not been proven to be active or inactive. This definition is used in
delineating Fault-Rupture Hazard Zones as mandated by the Alquist-Priolo Earthquake Fault Zoning
Act of 1972 and as most recently revised in 1997. The intent of this act is to assure that lUlvvise
urban development does not take place across the traces of active faults. Based on our revievv of the
Fault-Rupture Hazard Zones, the site is not located vvithin any Fault-Rupture Hazard Zone as created
by the Alquist-Priolo Act (Hart, 1997).
North San Diego County, like the rest of southern California, is seismically active as a result of
being located near the active margin betvveen the North American and Pacific tectonic plates. The
principal source of seismic activity is movement along the northvvest-trending regional fault zones
such as the San Andreas, San Jacinto, Coronado Banks (offshore) and Elsinore Faults Zones, as vvell
as along less active faults such as the Rose Canyon Fault Zone.
Our revievv of geologic literature pertaining to the site and general vicinity indicates there are no
knovvn major or active faults on or in the immediate vicinity ofthe site (Hannan, 1975, Weber, 1982,
and Jennings, 1994). Evidence for faulting vvas not encolUltered during our field investigation. The
nearest knovvn active fault is the Rose Canyon Fault Zone (RCFZ) vvhich is considered a Type B
seismic source per the 1997 Uniform Building Code (UBC) and is located approximately 5.0 miles
(8.1 kilometers) vvest of the site. The closest Type A seismic source is the Temecula segment of the
Elsinore Fault Zones located approximately 24.0 miles (38.7 kilometers) to the northeast.
Seismic Considerations
The principal seismic considerations for most structures in southern California are surface rupturing
of fault traces, damage caused by ground shaking or seismically induced ground settlement. The
possibility of damage due to ground rupture is considered lovv since active faults are not knovvn to
cross the site. The seismic hazard most likely to impact the site is ground-shaking resulting from an
earthquake on one of the major regional faults. The effects of seismic shaking can be reduced by
adhering to the most recent edition of the Uniform Building Code and design parameters of the
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2.7
040437-001
Structural Engineers Association of California.
Liquefaction of cohesion less soils can be caused by strong vibratory motion due to earthquakes.
Research and historical data indicate that loose granular soils underlain by a near-surface
groundwater table are most susceptible to liquefaction, while the stability of most silty clays and
clays is not adversely affected by vibratory motion. Because of the dense nature of the formational
material below the groundwater table, it is our opinion the potential for liquefaction or seismically
induced dynamic settlement at the site due to the design earthquake is low. Due to the site's
elevation of approximately 15 feet above mean sea level and relatively sheltered location on the
north side of the Agua Hedionda lagoon, the hazard from seiches and,tsunamis is also considered to
below.
2.6.1 Uniform Building Code Seismic Parameters
The site is located within Seismic Zone 4. The Rose Canyon Fault Zone (which is located
5.0 miles or 8.1 kilometers from the site) is considered a Type B seismic source per the
1997 UBC, Table 16-0). The soil profile type at the site is anticipated to be Type So while
the near source factors of Na = 1.0 and Ny = 1.2 are considered appropriate based on the
criteria of the 1997 UBC.
Engineering Characteristics of On-site Soils
Based on the results of our geotechnical investigation, laboratory testing of representative on-site
soils, and our professional experience on nearby sites with similar soils, the engineering
characteristics of the on-site soils are discussed below.
2.7.1
2.7.2
Expansion Potential
The majority of the onsite soils are expected to have a low to medium expansion
potential per the Uniform Building Code (UBC) criteria. However, highly expansive
clayey soils may be present on the site. If highly expansive soils are encountered during
the future grading operations, the highly expansive soils should be placed outside the
proposed building limits.
Soluble Sulfate Content
The National Association of Corrosion Engineers (NACE) defines corrosion as "a
deterioration of a substance or its properties because of a reaction with its environment".
From a geotechnical viewpoint, the "environment" is the prevailing foundation soils and
the "substances" are reinforced concrete foundations or various types of metallic buried
elements such as piles, pipes, etc., which are in contact with or within close vicinity of the
soils.
In general, soil environments that are detrimental to concrete have high concentrations of
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0404:37-001
soluble sulfates. Table 19-A-4 ofUBC, 1997 provides specific guidelines for the concrete
mix-design when the soluble sulfate content of the soil exceeds 0.1 percent by weight or
1000 parts per million (ppm). The results of our laboratory tests on representative soils
from the site indicate a soluble sulfate content of 0.18 percent which in aggregate suggests
that the concrete should be designed in accordance with the moderate category of Table 19-
A-4 of the 1997 UBC. The test results are provided in Appendix C.
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040437-001
3.0 CONCLUSIONS
Based on the results of our update geotechnical investigation at the subject site, it is our professional
opinion that the proposed development of the site is feasible from a geotechnical standpoint, provided the
following conclusions and recommendations are incorporated into the project plans, specifications, and
followed during site grading and construction.
The following is a summary of the geotechnical factors that may effect development of the site.
• Based on our subsurface exploration and review of pertinent geologic reports, the site is underlain by
artificial older fill soils and the Santiago Formation.
• Our analysis indicates that the artificial older fill soils are compressible in their present state and will
require removal and recompaction within areas of the proposed development.
• It is anticipated that the on-site soils can be excavated with conventional construction equipment.
• The existing on-site soils appear to be suitable for reuse as fill after it is removed to competent material
(provided they are placed in accordance with the recommendations presented herein).
• The expansion potential of the building pad soils is anticipated to be in the low to medium expansive
range (per UBC Criteria).
• Groundwater was encountered in Borings B-1 and B-3 at a depth of approximately 11.5 feet (or
approximately 4 feet msl). Groundwater is not anticipated to be a constraint to development.
• Active faults are not known to exist on or in the immediate vicinity of the site.
• The main seismic hazard that may affect the site is from ground shaking from one of the active
regional faults.
• Due to the fine-grained and cohesive characteristics of the subsurface soils and lack of groundwater,
the potential for liquefaction at the site is considered to be low.
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4.1
040437-001
4.0 RECOMMENDATIONS
Earthwork
We anticipate that earthwork at the site will consist of site preparation, removals of unsuitable soils,
fill placement, and trench excavation and backfill. We recommend the earthwork on-site be
performed in accordance with the following recommendations, the City of Carlsbad grading
requirements, and the General Earthwork and Grading Specifications for Rough-Grading (GEGS)
included in Appendix D. In case of conflict, the following recommendations shall supersede those
included as part of Appendix D.
4.1.1 Site Preparation
Prior to grading, the site should be cleared of surface obstructions, any existing debris,
vegetation, and unsuitable material. Vegetation and debris should be removed and properly
disposed of offsite. Holes results from the removal of buried obstructions that extend below
fmished site grades should be replaced with suitable compacted fill material.
Areas to receive fill and/or other surface improvements (after the removals of unsuitable
material are made) should be scarified to a minimum depth of 12 inches, brought to above-
optimum moisture contents, and recompacted to at least 90 percent relative compaction
(based on American Standard of Testing and Materials [ASTM] TestMethod D1557).
4.1.2 Removal and Recompaction of Potentially Compressible Soils
Due to the undocumented and potentially compressible characteristics of the on-site fill
soils, we recommend these soils be removed to competent material and recompacted
within 10 feet of the building footprint or envelope. The depth of the unsuitable material
removal is estimated to be on the order of approximately 4 to 10 feet in depth below the
existing ground surface.
The unsuitable material removed from the excavation may be used as fill on the site. Prior
to the placement of the soil as fill, it should be moisture conditioned (as needed) to obtain
a 2-percent above-optimum moisture content, and recompacted to a minimum 90 percent
relative compaction (based on ASTM Test Method D1557). The actual depth and extent
of the required removals should be determined during grading operations by the
geotechnical consultant.
4.1.3 Excavations
Excavations of the on-site soils may be accomplished with conventional earthwork
equipment. It is not anticipated that oversized rock (greater than 8 inches in maximum
dimension) will be encountered. All excavations should be carried out in accordance with
current OSHA requirements.
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4.2
040437-001
4.1.4 Fill Placement and Compaction
The on-site soils are generally suitable for use as compacted fill provided they are free of
organic material, trash or debris, and rock fragments larger than 8 inches in maximum
dimension. The fill should be brought to 2-percent above-optimum moisture content and
compacted in uniform lifts to at least 90 percent relative compaction based on the
laboratory maximum dry density (ASTM Test Method DI557). The optimum lift thickness
required to produce a uniformly compacted fill will depend on the type and size of
compaction equipment used. In general, fill should be placed in lifts not exceeding 8 inches
in compacted thickness. Placement and compaction of fill should be performed in general
accordance with the current City of Carlsbad grading ordinances, sound construction
practices, and the General Earthwork and Grading Specifications of Rough-grading
presented in Appendix D.
Foundation Design Considerations
A two-story structure is tentatively planned for the site. Foundations and slabs of the proposed
structure are assumed to be founded on soils possessing a low to medium expansion potential
(less than 90 per UBC Test Method 18-2). This should be confirmed as necessary during site
grading based on the actual soils exposed at finish grade.
The proposed foundation system should be designed by the structural engineer in accordance
with the following geotechnical parameters in accordance with governing codes and ordinances.
4.2.1 Post-Tensioned Foundation Design Considerations
We recommend that the post-tensioned slab ofthe structure be designed in accordance with
the following design parameters presented on Table 1 and the criteria of the 1997 edition of
the Uniform Building Code (lCBO, 1997). A post-tensioned foundation system designed
and constructed in accordance with the recommendations provided in this report is
expected to be structurally adequate for the support of the structure planned at the subject
site provided our recommendations presented herein are followed. Adhering to the design
and maintenance recommendations presented in this report will help ensure that expansive
soil-related effects to the structure, if any, are limited to cosmetic distresses, with no
adverse impact to the overall structural integrity of the structure.
Please note that UBC Chapter 18 is based on certain climatological assumptions with
regard to soil-moisture conditions around and beneath the post-tensioned slabs. Soil-
moisture change below slabs is the major factor in expansive soil problems. The UBC
design method does not contain specific provisions to account for the effects of
irrigation, pre saturation, or other non-climate-related influences on the moisture content
of subgrade soils. We have, therefore, modified our geotechnical parameters to account
for reasonable irrigation practices, and a reasonable degree of maintenance and
responsibility. If proper landscaping and irrigation practices are not adhered to, then
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040437~OOl
some degree of distress is likely to occur. Based on our previous experience, this distress
typically does not impact the structural integrity of the structure.
We also recommend that soil-moisture around the immediate perimeter of the slab be
maintained at near optimum-moisture content (or above) during construction and up to
occupancy of the structure. The owner should be informed and educated regarding the
importance of maintaining a constant level of soil-moisture and should be made aware of
the potential negative consequences of both excessive watering, as well as allowing
expansive soils to lose moisture (i.e., the soil will undergo shrinkage as it dries up,
followed by swelling during the winter, rainy season or when irrigation is resumed,
resulting in distress to improvements and structures). Our recommendations for
landscaping and surface drainage are provided later in this report.
Table 1
Post-Tensioned Foundation Design Recommendations
Expansion Index (UBC 18-I-B)
Design Criteria Medium
Edge Moisture Variation, em Center Lift: 5.5 feet
Edge Lift: 4.0 feet
Differential Swell, Ym Center Lift: 2.5 inches
Edge Lift: 1.0 inches
Acceptable Design Deflection Structural Engineer/Architect
and governing codes
Minimum Perimeter Foundation Embedment 18 inches
Modules of Subgrade Reaction 120 pci
Long-term differential settlement is anticipated to occur at the site due to the variability
of the engineered fill material. This settlement is not considered an impact to the
proposed structure as long as it is factored into the design of the foundation. In order to
simplify our recommendations for the foundation, we have factored in the anticipated
settlement into the geotechnical perimeters for foundation design.
The post-tensioned foundation and slab should be designed in accordance with the design
presented above, acceptable deflection criteria determined by the structural engineer, and/or
architect and governing codes.
The slab should be underlain by a minimum of 2 inches of clean sand (sand equivalent
greater than 30) which is in turn underlain by a vapor barrier and an additional 2 inches of
clean sand. The vapor barrier should be sealed at all penetrations and laps. Moisture vapor
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transmission may be additionally reduced by use of concrete additives. Moisture barriers
can retard, but not eliminate moisture vapor movement from the underlying soils up
through the slabs. We recommend that the floor covering installer test the moisture vapor
flux rate prior to attempting applications of the flooring. "Breathable" floor coverings
should be considered if the vapor flux rates are high. A slipsheet or equivalent should be
utilized above the concrete slab if crack-sensitive floor coverings (such as ceramic tiles,
etc.) are to be placed directly on the concrete slab.
Our experience indicates that use of reinforcement in slabs and foundations will generally
reduce the potential for drying and shrinkage cracking. However, some cracking should be
expected as the concrete cures. Minor cracking is considered normal; however, it is often
aggravated by a high water/cement ratio, high concrete temperature at the time of
placement, small nominal aggregate size, and rapid moisture loss due to hot, dry and/or
windy weather conditions during placement and curing. Cracking due to temperature and
moisture fluctuations can also be expected. The use oflow slump concrete (not exceeding 4
to 5 inches at the time of placement) can reduce the potential for shrinkage cracking and the
action of tensioning the tendons can close small shrinkage cracks. fu addition to the careful
control of water/cement ratios and slump of concrete, application of 50 percent of the
design post-tensioning load within three to four days of slab pour may be an effective
method of reducing the cracking potential.
4.2.2 Slab Sub grade Soil Presaturation
The slab subgrade soils underlying the post-tensioned foundation system should be
presoaked to a minimum 130 percent of the optimum moisture content to a depth of at least
18 inches prior to placement of the moisture barrier and slab concrete.
Presoaking or moisture conditioning may be achieved in a number of ways. But based on
our professional experience, we have found that minimizing the moisture loss on the pad
(by periodic wetting to keep the upper portion of the pad from drying out) and/or
berming the building pad and flooding for a short period of time (days to a few weeks)
are some of the more efficient ways to meet the presoaking recommendations. If flooding
is performed, a couple of days to let the upper portion of the pad dry out and form a crust
so equipment can be utilized should be anticipated. fu addition, we recommend the
contractor place the fmal 2 feet of material at significantly over optimum moisture
content to reduce the difficulties associated with presoaking.
4.2.3 Seismic Design Parameters
The site lies within Seismic Zone 4, as defined in the UBC, 1997 edition. The nearest
known active fault is the Rose Canyon Fault Zone, which is located approximately
5.0 miles (8.1 kilometers), west ofthe site. The following data should be considered for the
seismic analysis of the proposed structure:
• Causative Fault: Rose Canyon Fault Zone
• Maximum Magnitude: 6.9
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040437-001
• Seismic Source Type: B
• Seismic Zone Factor: 0.40
• Soil Profile Type: SD
• Near Source Factors: Na= 1.01Nv = 1.2
4.2.4 Foundation Setback From Slope Faces
We recommend a minimum horizontal setback distance from the face of descending
slopes for all structural footings and settlement-sensitive structures. This distance is
measured from the outside edge of the footing, horizontally to the descending slope face
(or to the face of a retaining wall) and should be a minimum of W2, where H is the slope
height (in feet). The setback should not be less than 10 feet and need not be greater than
15 feet. Please note that the soils within the structural setback area possess poor lateral
stability, and improvements (such as retaining walls, sidewalks, fences, pavements, etc.)
constructed within this setback area may be subject to lateral movement and/or
differential settlement.
Cement Type for Construction
The soluble sulfate content testing of a representative sample of the onsite soil indicates the soils
possess a moderate soluble sulfate content based on the 1997 UBC criteria. Concrete in contact
with the on-site soils should be designed in accordance with Table 19-A-4 of the 1997 UBC. This
should be confirmed by laboratory testing of the fmish grade soils upon completion of the site
grading operations.
Lateral Earth Pressure and Retaining Wall Design
Embedded structural walls should be designed for lateral earth pressures exerted on them. The
magnitude of these pressures depends on the amount of deformation that the wall can yield under
load. If the wall can yield enough to mobilize the full shear strength of the soil, it can be designed
for "active" pressure. If the wall cannot yield under the applied load, the shear strength of the soil
cannot be mobilized and the earth pressure will be higher. Such walls should be designed for "at
rest" conditions. If a structure moves toward the soils, the resulting resistance developed by the soil
is the "passive" resistance.
To design an unrestrained wall, such as cantilever wall, the active earth pressure may be used.
For a restrained retaining wall, such as a basement wall, the at-rest pressure should be used.
Further, for sliding resistance, the friction coefficient of 0.35 may be used at the concrete and
soil interface. In combining the total lateral resistance, the passive pressure or the frictional
resistance should be reduced by 50 percent.
Wall footings may be designed in accordance with structural considerations. The passive resistance
value may be increased by one-third when considering loads of short duration including wind or
seismic loads. The horizontal distance between foundation elements providing passive resistance
should be a minimum of three times the depth of the elements to allow full development of this
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040437-001
passive pressure. The total depth of retained earth for design of cantilever walls should be the
vertical distance below the ground surface measured at the wall face for stem design or measured at
the heel of the footing for overturning and sliding. All retaining structures should be provided with
a drainage blanket or drains (as indicated in Figure 3) and appropriately waterproofed. Surcharge
loading effects from adjacent structures should be evaluated by the geotechnical and structural
engineers.
For design purposes, the recommended equivalent fluid pressure for each case for walls founded
above the static groundwater and backfilled with imported select granular soils having a sand
equivalent of30 or greater is provided in Table 2. The equivalent fluid pressure values assume free-
draining conditions. If conditions other than those assumed above are anticipated, the equivalent
fluid pressure values should be provided on an individual-case basis by the geotechnical engineer.
All retaining wall structures should be provided with appropriate water proofmg and drainage. The
outlet pipe should be sloped to drain to a suitable outlet. Typical drainage design is illustrated on
Figure 3.
All excavations should be made in accordance with the most current OSHA requirements. The
granular and native backfill soils should be compacted to at le.ast 90 percent relative compaction
(based on ASTM Test Method D1557). The walls should be constructed and backfilled as soon as
possible after back cut excavation. Prolonged exposure of back cut slopes may result in some
localized slope instability.
Foundations for retaining walls in competent properly compacted fill should be embedded at least
18 inches below lowest adjacent grade. At this depth, an allowable bearing capacity of 2,000 psf
may be assumed.
Table 2
Lateral Earth Pressures
Equivalent Fluid Weight (pct)
Import Soil with a SE of30 or Greater
Conditions Level Backfill 2: 1 Backfill
Active 35 60
At-Rest 55 70
Passive 350 350
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RETAINING WALL BACKFILL AND
DRAINAGE DETAIL
OPTION 2: GRAVEL _ WRAPPED
IN FILTER FABRIC
For Maximum 8-Foot High Walls with
On-Site Soils Having Very Low to Low
Expansion Potentials (i.e. on Expansion
Index of 50 or Less)
SLOPE
OR LrvEl
OPTION 1: PIPE SURROUNDED WITH
CLASS 2 PERMEABLE MATERIAL
WATERPROOFING --/---J
(SEE GENERAL NOTES)
WEEP HOLE (SEE NOTE 5)
L£VELO~
" TO 1 ~ INCH SIZE GRAVEL WRAPPED IN ALTER
'ABRIC
SLOPE
OR LEVEL SLOPE . ~~~
WATERPROOfiNG
(SEE GENERAL NOTES)
Class 2 Filter Permeable Material Gradation
Per Caltrans Specifications .
WEEP HOLE
(SEE NOTE 5)
LEVElO~ SLOPE . ~~~
GENERAL NOTES:
12" MINIMUM
CLASS 2 PERMEABLE FILTER MATERIAL
(SEE GRADATION)
4 INCH DIAMETER
PERFORATED PIPE
(SEE NOTE 3)
Sieve Size Percent Passing-
1" 100
3/4" 90-100
3/8" 40-100 25.,.40 No.4 18-33 No.8
No. 30 5-15
No. 50 0-7
No. 200 0-3
• Waterproofing should be provided where moisture nuisance problem through the wall is undesirable
• Water proofing of the walls is not under purview of the geotechnical engineer
• All drains should have a gradient of 1 percent minimum
• Outlet portion of the subdrain should hove a 4-inch diameter solid pipe discharged into a suitable disposal orea designed
by the project engineer. The subdrain pipe should be accessible for maintenance (rodding)
• Other subdrain backfl1l options are subject to the review by the geotechnical engineer and modification of design
parameters
Notes:
i) Sand should have a sand equivalent of 30 or greater and may be densified by water jetting
2) 1 Cu. ft. per ft. of 1/4-to 1 1/2-inch size grovel wrapped in filter fabric
3) Pipe type should be ASTM 01527 Acrylonitrile Butadiene Styrene (ABS) SOR35 or ASTM 01785 Polyvinyl Chloride-plastic
(PVC). SChedule 40. Armco A2000 PVC. or approved equivolent. Pipe should be installed with perforations down. Perforations
should be 3/8 inch in diameter placed at the ends of a 120-degree arc in two rows at 3-inch on center (staggered)
4) Filter fabric should be Mirafi 140NC or approved equivalent
5) Weephole should be 3-inch minimum diameter and provided at 10-foot maximum intervals. If exposure is permitted.
weepholes should be located 12 inches above finished grade. If exposure is not permitted such as for a wall adjacent to a
Sidewalk/curb. a pipe under the sidewalk to be discharged through the curb face or equivalent should be provided. For a
basement-type wall. a proper subdrain outlet system should be provided
6) Retalning wall pions should be reviewed and approved by the geotechnical engineer
7) Walls over eight feet in height are subject to a special review by the geotechnical engineer and modifications to the
above requirements
RETAINING WALL BACKFILL
AND SUBDRAIN DETAIL
(rev. June 2000)
PROJECT NO. 042437-001
PROJECT NAME Lot 13 of Map No. 5162
Carlsbad. California
Leighton and Associates, Inc. Figure No.3
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4.5
4.6
4.7
040437-001
Surface Drainage and Lot Maintenance
Positive drainage of surface water away from the structure is very important. No water should be
allowed to pond adjacent to the building. Positive drainage may be accomplished by providing
drainage away from the building at a gradient of at least 2 percent for a distance of at least 5 feet,
and further maintained by a swale of drainage path at a gradient of at least I-percent. Where
necessary, drainage paths may be shortened by use of area drains and collector pipes. Eave gutters
also help reduce water infiltration into the subgrade soils if the downspouts are properly connected
to appropriate outlets.
Planters with open bottoms adjacent to buildings should be avoided, if possible. Planters should not
be designed adjacent to buildings unless properly designed with a liner to prevent moisture
variations below the foundation.
Graded Slopes
It is recommended that all graded slopes within the development be planted with drought-tolerant
ground cover vegetation as soon as practical to protect against erosion by reducing runoff velocity.
Deep-rooted vegetation should also be established to protect against surficial slumping.
Oversteepening of existing slopes should be avoided during fine grading and construction unless
supported by appropriately designed retaining structures.
We recommend terrace drains on the slopes be designed by the civil engineer and be constructed in
accordance with current County of San Diego specifications. Design of surface drainage provisions
is within the purview ofthe project civil engineer.
Plan Review and Construction Observation
Final project drawings should be checked by Leighton and Associates before grading to see that
the recommendations in this report are incorporated in project plans. Construction observation of
all onsite excavations and field density testing of all compacted fill should be performed by a
representative of this office. We recommend that a geologist map all excavations during grading
for the presence of potentially adverse geologic conditions. All footing excavations should be
reviewed by this office prior to placing steel or concrete.
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040437-001
5.0 LIMITATIONS
The conclusions and recommendations in this report are based in part upon data that were obtained from
a limited number of observations, site visits, excavations, samples, and tests. Such information is by
necessity incomplete. The nature of many sites is such that differing geotechnical or geological
conditions can occur within small distances and under varying climatic conditions. Changes in
subsurface conditions can and do occur over time. Therefore, the findings, conclusions, and
recommendations presented in this report can be relied upon only if Leighton and Associates has the
opportunity to observe the subsurface conditions during grading and construction of the project, in order
to confirm that our preliminary findings are representative for the site.
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APPENDIX A
References
Blake, 1996, EQFAULT, Version 3.0.
---, 1998, FRISKSP.
CDMG, 1996, Probabilistic Seismic Hazard Assessment for the State of California, Open-File Report,
96-08, California Division of Mines and Geology.
Eisenberg, L.I. and Abbott, P.L., 1985, Eocene Lithofacies and Geologic History, Northern San Diego
County in Abbott, P.L., ed., On the Manner of Deposition of the Eocene Strata in Northern
San Diego County: San Diego Association of Geologists, Field Trip Guidebook, pp. 19-35.
Hannan, D., 1975, Faulting in the Oceanside, Carlsbad and Vista Areas, Northern San Diego County,
California in Ross, A., and Dowlens, R.J., eds., Studies on the Geology of Camp Pendleton
and Western San Diego County, California: San Diego Association of Geologists, pp. 56-
59.
Hart, E.W., 1997, Fault-Rupture Hazard Zones in California, Alquist-Priolo Special Studies Zones Act of
1972 with Index to Special Studies Zones Maps: Department of Conservation, Division of
Mines and Geology, Special Publication 42.
International Conference of Building Officials (lCBO), 1997, Uniform Building Code, Volume I -
Administrative, Fire-and Life-Safety, and Field Inspection Provisions, Volume IT -Structural
Engineering Design Provisions, and Volume III -Material, Testing and Installation Provision,
ICBO.
Jennings, C.W., 1994, Fault Activity Map of California and Adjacent Areas; California Division of Mines
and Geology, Geologic Data Map 6, Scale 1 :750,000.
Leighton and Associates, Inc, In-house Unpublished and Published Data.
Lindvall, S.C., and Rockwell, T.K., 1995, Holocene Activity of the Rose Canyon Fault Zone in San Di~go,
California: Journal of Geophysical Research, V. 100, No. B12, p. 24,124-24, 132.
Rockwell, T.K., and Lindvall, S.C., 1990, Holocene Activity of the Rose Canyon Fault in San Diego,
California, Based on Trench Exposures and Tectonic Geomorphology; Geological Society
of America, Abstracts with Programs.
----, 1991, Minimum Holocene Slip Rate for the Rose Canyon Fault in. San Diego, California in
Environmental Perils, San Diego Region: San Diego Association of Geologists, p. 37-46.
Slemmons, D.B., and Depolo, C.M., 1986, Evaluation of Active Faulting and Associated Hazards in Active
Tectonics (Studies in Geophysics): National Academy Press,p. 45-62.
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040437-001
References (continued)
Tan, S.S., and Kennedy, M.P., 1996, Geologic Maps of -the Northwestern Part of San Diego County,
California: California Division of Mines and Geology, DMG Open-File Report 96-02, 2
Plates.
Treiman, lA., 1984, The Rose Canyon Fault Zone: A Review and Analysis, California Division of Mines
and Geology, Funded by Federal Management Agency Cooperative Agreement EMF-83-K-
0148.
----, 1990, Rose Canyon Fault Zone, San Diego County, California: California Division of Mines
and Geology, Fault Evaluation Report FER-216 pp. 6-8, and Portion of 1 Plate.
----, 1993, The Rose Canyon Fault Zone, Southern California: California Division of Mines and
Geology, Open-File Report 93-2, 45p.
Weber, F.H., 1982, Recent Slope Failures, Ancient Landslides and Related Geology of the Northern-Central
Coastal Area, San Diego County, California: California Division of Mines and Geology,
Open File Report 82-12LA, 77 p.
Wilson, K.L., 1972, Eocene and Related Geology of a Portion of the San Luis Rey and Encinitas
Quadrangles, San Diego County, California: Master Thesis, University of California at
Riverside, 123 p.
Working Group on California Earthquake Probabilities, 1995, Seismic Hazards in Southern California:
Probable Earthquakes, 1994 to 2024: Bulletin of the Seismological Society of America, V.
95, No.2, p. 379-439.
Ziony, J.I., and Yerkes, R.F., 1985, Evaluating Earthquake and Surface-Faulting Potential in Ziony, ed.,
1985, Evaluating Earthquake Hazards in the Los Angeles, Region-An Earth-Science
Perspective: U.S. Geological Survey, Professional Paper 1360, p. 43-91.
Aerial Photographs
Date Source Flight Photo Number
1953 USDA 14M t8 and 19
A-2
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GEOTECHNICAL BORING LOG KEY
Date __________ _ Sheet _1_" Of _1_"
Project KEY TO BORING LOG GRAPmCS Project No.
Drilling Co.
Hole Diameter
Elevation Top of Hole +/-
. c a 0"" 0 .I:."" III Z ._+-.-
+'01 +-+. .I:.c) 01 01 ttl 01 0.01 0.0 +-->'+-0101 ttl...! a a. ~'"" C0 t.. Z (.!) S ttl LLJ (I)
0 W ~
r"'>A~~"'"
I I 5 ~II
~ j
~ ~
~ j-:;
10
',-
-:1 -
~
b-,,-!_~o rO"",-~
10 \I' c: (m(
15 p~ 1 T~
~
~
1---:--
1-20
::17/\ f
~ , \
1-
~t; <.
~
///,$/j,
251M
XXX):
-
-
"10
505A( 11/77)
Drive Weight
ft Ref or Datum
:Jl "" iii"" +-+-OI~ .-t..'"" III • 1110 Ill"" ttI~ ;,+-3 0 C'+--u aLL. 010 'tl c u . -t.. co. ._ 01 _(I) COOl '"" a+-:Jl ,;:C ._:::) a.. t.. a ~'"" c u
CL
CH
OL-OH
SPT ML , SAMP" IR
MH
~A1}PI LR CL-ML
ML-SM
CL-SC
SC-SM
SW
SP
SM
SC
GW
INn 'VI ~: ¥ GP ~lHT"~ 1 i..rn GM
GC
Type of Rig
Drop in.
"GEOTECHNICAL DESCRIPTION
Logged By
Sampled By
Inorganic clay of low to medium plastiCity; gravelly clay; sandy clay; silty clay; lean
clay
Inorganic clay or high plasticity; fat clay
Organic clay, silt or silty clay-clayey silt mixtures
; silt; very~ sand; silty or clayey fine sand; clayey silt with low plasticity
Inorganic silt; diatomaceous fine sandy or silty soils; elastic silt
Low plasticity<:iay to silt mixture
Sandy silt to silty sand mixture,
Sandy clay to ~ sand 'mixtUre
Clayey sand to silty sand mixture
Well graded sand; gravelly sand, little or no fines
Poorly graded sand; gravelly sand, little or no fines
Silty sand; poorly graded sand-silt mi~ture
Clayey sand; poorly graded sand; clay mixture
Well graded gravel ! mixture, little or no fines"
Poorly graded gravel; gravel-sand mixture, little or no fines
~ Silty gravel; .a mixture
" Clayey gravel; _1, mixture
Sandstone
Siltstone
nL
Breccia (angulargravel and cobbles or mal rt -'-~)
n ~un4~--'i1\,e~ cobble ""
Igneous granitic or granitic type rock
Metavolcanic or rock
Artificial or fill
Asnhaltic concrete
Portland cement concrete
LEIGHTON & ASSOCIATES
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Date ___ ~5~-~10~-~01~ __
Project
Drilling Co.
Hole Diameter
Elevation Top of Hole
C ,~" .r:." 0 .-.......... .......... .r:.m 111 01 n.Q1 n.o :>01 0101 111...1 ~~ o~ '-CD LLI
15 0 :
:
:
:
:
10 5 :
.' :
:
:
:
505A ( 11 /77)
til 01 ..... 0 z
8 in.
+1-15
. o Z
01
n. s 111 (/)
Bag-l
@0-2'
2
Bag-2
@9-U'
3
4
5
6
GEOTECHNICAL BORING LOG B .. 1
Lappin/Hedionda
F&C Drilling
Drive Weight
ft. Ref. or Datum
j'I " iii" ..... ..... Q1~ til •
til 0 til"
,-v Ill(/)
3 0 C'f-::::I ..... .
oLl. 010 tic -u u. -'-on. ._ 01 _(/) alQl v 0 ..... a.. j'I :£:C '-::i '-0 gv 0 u
SM
32 114.4 7.0
10 97.2 7.0
Sheet _1_ of _, _2_
Project No; 040437-001
Type of Rig Hollow-Stem Auger
140 pounds Drop ,30 in.
Mean Sea Level
GEOTECHNICAL DESCRIPTION
Logged By
Sampled By
ARTIFICIAL OLDER FILL CAfo)
GJM
GJM
@ 0': Brown fnie to medium silty SAND, damp to moist, medium dense
@ 2': Gray to pale gray, fme to medium silty SAND, damp, moist, mt<dium dense
@ 5': Orange-brown, fine to mediumcsilty SAND, friable, damp to moist, loose
-SC--SANTIAGO FORMA:fIoN-CTs) - - - - - - - - - - - - - - - - - - - - - -
@ 9': Dark gray, clayey fine to medium SANDSTONE; moist, medium dense,
15 118.0 12.8 slightly weathered
23 113.9 15.9
28 110.0 17.0
31 114.1 16.2
@ 11.5': Ground water encountered
@ 15': Light gray-brown, clayey, fme to medium SANDSTONE, saturated,
medium dense
@ 20': Light gray-brown, clayey, fine to coarse SANDSTONE; saturated, medium
dense to dense, massive
@ 25': Lightgray-brown, clayey, fine to coarse SANDSTONE; saturated, medium,
dense to'dense, massive
LEIGHTON & ASSOCIATES
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Date ___ '--~5·..::.1:.::.0...::·0:..:::1 __ _
Project
Drilling Co.
Hole Diameter
Elevation Top of Hole
C '~""' 0 .t:.""' .-........ ........ .t:.01 tII W o.W 0.0 >W WW tII-J !~ c~ '" CD UJ
-15 30 l ~I··· . -: :-;-:-: . '. " .
-
-
-
-20 35-
-
-
-
-
-25 40-
-
-
-
-
-30 45-
-
-
-
-
-35 50-
-
-
-
-
-40 55-
-
-
-
-
-<IS 110
505A(11/77)
8 in.
+/ 15 -
.
0
til Z
W W .... -0 0. Z 5 til (I)
7
GEOTECHNICAL BORING LOG B-1
Sheet _2_ of _2_
LappinlHedionda Project No. . 040437·001
F&C Drilling Type of Rig HoIlow~Stem Auger
Drive Weight ________ ..::.1:...::4-"'-0...,p:.;::o.=DD=,d=s"--_______ Drop 30 in.
ft Ref or Datum Mean Sea Level
:Jl ""' ui""' .... .... WX GEOTECHNICAL DESCRIPTION .-",v til •
til 0 til,,", tII~ 3 0 C .... ;j .... -u oll. WO tic u.
-", co. ._ W _(I) lOW v 0 .... Logged By GJM a. :Jl E C '-:::i '" 0 Ov Sampled By GJM c u (I)
53/6" 121.9 12.9 SM SANTIAgO FORMATIQN (Ts) (continued)
@ 30': Li~ht gray, silty fine to 'coarse SANDSTONE, very moist, very dense,
maSSIve
Total Depth = 31.5 Feet
Ground water encountered at 11.5 feet.at time of drilling
BackfIlled with bentonite on 5/10/01
.
LEIGHTON & ASSOCIATES
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Date ____ .::.5-..::1~O~-O~I __ _
Project
Drilling Co.
FIole Diameter
Elevation Top of FIole
C 0", 0 .J::.'" .-.-+-+-+-.J::.C) +-0) 1110) 0.0) 0.0 0)0) III...J > .... o)v o~ t.,
(.!)
IJ.J
15 0 "'7/ -~ ;:~~ -~ -
-~ 10 5-
I -
-
-~ -
5 10-'.' ... ' .. .. -' .. . .
' .. -
' ..
-' ..
' .. -...
8 in.
+/-15
. 0
fIl z
0) 0) +-0 -0. z S III en
1
2
3
GEOTECHNICAL BORING LOG B-2
Sheet _1_ of _1._
LappinlHedionda Project No. 040437~OOl
F &C Drilling Type of Rig Hollow-Stem Auger
Drive Weight ________ ..::1:;..:4~O~p~o.=un::;ds=_ _ __'_ ___ ---· Drop .30 in.
ft Ref or Datum Mean Sea Level
::n '" iii'" +-+-O)~ GEOTECHNICAL DESCRIPTION fIlO .-t.,v fIl •
fIl'" III~ 3 0 C~ ~+--u 0Ll. 0)0 tic u. 00. -t., ._ 0) _en alO) v o+-Logged By GJM a.. ::n l:c '-::5 t., 0 ~v Sampled By GJM. 0 u
SM-SC ARTIFICIAL OLDER FILL (Afo)
@ 0': Medium brown, clayey to silty SAND; moist, medium dense
14 108.5 17.5 SC @ 2': Brown to dark gray, clayey SAND, damp to moist, stiff
31 118.5 11.7 -SC---SANTIAGO FORMATION-ers) - - - - - - -.., - - - - - - - - - - - - - -
@ 5': Light orange-gray, slightly clayey, fIne· to coarse SANDSTONE, d!l1llP to
moist, dense
46 120.9 12.6 SM @ 10': Pal~ gray, fIne to medium silty SANDSTONE, damp to moist, dense,
massIVe
0 15-4 5015" 118.5 12.7 @ 15': Gray to olive-gray, fme silty SANPSTONE, damp, moist, dense to very
' .. dense ,
-Total Depth = 16 Feet No ground water encountered at time of drilling
Backfilled with soil cuttings on 5/10/01 -
-
-5 20-
-
-
-
-
-10 25-
-
-
-
-
_1 'i "In
505A(11J77> LEIGHTON & ASSOCIATES
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Date ____ ~5...::-1=.;::;0.....:-0=1 __ _
Project
Drilling Co.
Hole Diameter
Elevation Top of Hole
c '~"""' 0 .s::."""' .-+-+-+-+-.s::.m IlIQI .o.g: 0.0 :>QI 1lI-l QI ..... QI ..... C v t., _v. CD I.LI
15 0 ..
' .. .. -' ..
-~ -
-~ 10 5-~ -
-~ -~ ..:.
5 10-
-
-
-~ -
0 15-~ -: .. ''/-
-
-
-
-5 20-
-
-
-
-
-10 25-
-
-
-
-
_1 ".
505A(11/77>
8 in.
+/-15
.
0
I,/) z
QI QI +-0 -0. Z E III (I)
1
2
3
4
GEOTECHNICAL BORING LOG B-3
Sheet ---L,.. of _1 __ _
LappinlHedionda Project No. 040437-001
F &C Drilling Type of Rig Hollow-Stem Anger
Drive Weight ________ -::1:::4~0~p::::o~un~ds=_ __________ Drop 30 in.
Ref orDatum Mean Sea Level -ft
J) """' iii"""' +-+-QI~ GEOTECHNICAL DESCRIPfION 1,/)0 .-t.,v I,/) •
1,/)",,", III (I)
::3 0 c ..... ::J+-. -u oLl.. QlO tic u. co. -t., .-QI _(I) alQl v o+-Logged By GJM
0-J) :E:c .-::; t., 0 ~v C u Sampled By GJM
SM ARTIFICIAL OLDER FILL (Afo)
@ 0': Brown, silty SAND; damp to slightly moist, medium dense
12 104.3 12.7 CL @2': Gray to medium coarse sandy CLAY, damp, moist, stiff
18 109.7 17.9 @ 5': Dark gray to g.ray, !p.edium coarse SAND clay, damp to moist, stiff,
scattered orgamcs _ _
-SC--sANTIAGO FORMATION-ers) - - - - - - - - - - - - - - - - - - - - - -
@ 6': Medium to light brown, clayey, fme to coarse SANDSTONE; moist,
medium dense
20 115.0 14.4 @ 10': Pale gray clayey fme to coarse SANDSTONE, damp to moist, medium
dense, scattered mica and few gravels
¥ @ 11.5': Ground water encountered
25 116.8 15.6 @ 15': Gray to pale gray, clayey, fine to coarse SANDSTONE; saturated, medium
dense, massive
Total Depth = 16.5 Feet
Ground water encountered at 11.5 feet at time' of drilling
Backfilled with soil cuttings on 5110/01
LEIGHTON & ASSOCIATES
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040437-001
APPENDIXC
Laboratory Testing Procedures and Test Results
Expansion Index Tests: The expansion potential of selected materials was evaluated by the Expansion Index .
Test, D.B.C. Standard No. 18-2 and/or ASTM Test Method 4829. Specimens are molded under a given
compactive energy to approximately the optimum moisture content and approximately 50 percent saturation
or approximately 90 percent relative compaction. The prepared I-inch thick by 4-inch diameter specimens
are loaded to an equivalent 144 psf surcharge and are inundated with tap water until volumetric· equilibrium
is reached. The results of these tests are presented in the table below:
Sample Sample Description Expansion Index Expansion Potential Location
B-1 #1 @0-2' Brown silty SAND 24 Low
Soluble Sulfates: The soluble sulfate contents of selected samples were determined by standard geochemical
methods (Caltrans Test Method CT417). The test results are presented in the table below:
*
Sample Location Sample Description Sulfate Content Potential Degree of Sulfate Attack* (%)
B-1 #1 @0-2' Brown silty SAND 0.18 Moderate
Based on the 1997 edition of the Uniform Building Code, Table No. 19-A-4, prepared by the
International Conference of Building Officials (lCBO, 1997).
Moisture and Density Determination Tests: Moisture content and dry density determinations were
performed on relatively undisturbed samples obtained from the test borings and/or trenches. The results of
these tests are presented in the boring and/or trench logs. Where applicable, only moisture content was
determined from "undisturbed" or disturbed samples.
Hyrdoconsolidation Tests: Hydroconsolidation tests were performed on selected relatively undisturbed ring
samples. Samples were placed in a consolidometer and a load approximately equal to thein-situ overburden
pressure was applied. Water was then added to the sample and the percent hydroconsoliclation for the load
cycle was recorded as the ratio of the amount of vertical compression to the original i-inch height. The·
percent hydroconsolidation is presented below:
Sample Location Percent Hydroconsolidation
B-1 #2@5' 0.7
B-3 #2@5' None
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Leighton and Associates, Inc.
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
Pagelof6
LEIGHTON AND ASSOCIATES,INC.
GENERAL EARTHWORK AND GRADING SPECIFICATIONS FOR ROUGH GRADING
1.0
3030.1094
General
1.1 Intent: These General Earthwork and Grading Specifications are for the grading and
earthwork shown on the approved grading planes) and/or indicated in the geotechnical
report(s). These Specifications are a part of the recommendations contained in the
geotechnical report(s). In case of conflict, the specific recommendations in the
geotechnical report shall supersede these more general Specifications. Observations of the
earthwork by the project Geotechnical Consultant during the course of grading may result
in new or revised recommendations that could supersede these specifications or the
recommendations in the geotechnicalreport(s).
1.2 The Geotechnical Consultant of Record: Prior to commencement of work, the owner shall
employ the Geotechnical Consultant of Record (Geotechnical Consultant). The
Geotechnical Consultants shall be responsible for reviewing the approved geotechnical
report(s) and accepting the adequacy of the preliminary geotechnical findings, conc1ilsions~
and recommendations prior to the commencementofthe grading.
Prior to commencement of grading, the Geotechnical Consultant shall review the "work
plan" prepared by the Earthwork Contractor (Contractor) and schedule sufficient personnel
to perfonn the appropriate level of observation, mapping, and compactiontesting.
During the grading and earthwork operations, the Geotechnical Consultant shall observe,
map, and document the subsurface exposures to verify the geotechnical design
assumptions. If the observed conditions are found to be significantly different than the
interpreted assumptions during the design phase, the Geotechnical Consultant shall infonn
the owner, recommend appropriate changes in design to accommodate the observed
conditions, and notify the review agency where required. Subsurface areas to be
geotechnically observed, mapped, elevations recorded, and/or tested include natural ground
after it has been cleared for receiving fill but before -fill is placed, bottoms of all "remedial
removal" areas, all key bottoms, and benches made on sloping ground to receive fill.
The Geotechnical Consultant shall observe the moisture-conditioningand processing of the
subgrade and fill materials and perfonn relative compaction testing of fill to detennine the
attained level of compaction. The Geotechnical Consultant shall provide the test results to
the owner and the Contractor on a routine and frequent basis.
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Leighton and Associates/Inc.
GENERAL EARTHWORK AND GRADINGSPEOFICATIONS
Page2of6
1.3 The Earthwork Contractor: The Earthwork Contractor (Contractor) shall be qualifIed,
experienced, and knowledgeable in earthwork logistics, preparation and processing of
ground to receive fill, moisture-conditioning and processing of fill, and compacting fill.
The Contractor shall review and accept the plans, geotechnical report(s), and these
Specifications prior to commencement of grading. The Contractor shall be solely
responsible for performing the grading in accordance with the plans and 'specifications.
"The -Contractor shall prepare' and submit to' the owner and the Geotechnical Consultant a
work plan that indicates the sequence of earthwork grading, the number of "spreads" of
work and the estimated quantities of daily earthwork contemplated for the site prior to
. -.·.d· .. "-commencement of grading. -: The Contractor shall.informthe·owner and the Geotechnical
Consultant of changes in work schedules and updates to the work. plan at least 24 hours in
advance of such changes so that appropriate observations and tests can be planned and
accomplished. The Contractor shall not assume that the' Geotechnical Consultant is aware
of all grading operations.
The Contractor shall have the sole responsibility to provide adequate equipment and
.. ,.';,' .. ,methods to accomplish the earthwork in.accordance with the applicable grading codes and
agency ordinances, these Specifications, and the recommendations in the approved
geotechnical report(s) and grading planes). If, in the opinion of the Geotechnical
.. ,... Consultant,. unsatisfactory conditions, such as unsuitable soil, Improperri:lOisture condition,
inadequate compaction, insufficient buttress 'key size, adverse weather, etc.~ are resultIng in
a quality of work less than required in these specifications, the Geotechnical Consultant
shall reject the work and may recommend to the owner that construction be stopped until
the conditions are rectified.
2.0 Preparation of Areas to be Filled
2.1
3030.1094
Clearing and ·Grubbing: Vegetation, such as· brush, grass, roots, and other deleterious
material shall be sufficiently removed and properly disposed of in a method acceptable to
the owner, governing agencies, and the Geotechnical Consultant.
The Geotechnical Consultant shall evaluate the extent of these removals depending on
specific site conditions. Earth fiU material shall not contain more than 1 percent of organic
materials (by volume). No fill lift shall contain more than 5 percent of organic matter.
Nesting of the organic materials shall not be allowed.
If potentially hazardous materials are encountered, the Contractor shall stop work in the
affected area, and a hazardous material specialist shall be informed immediately fof' proper
.". evaluation and handling. of these materials prior to continuing to work iIi that area. .
As presently defined by the State of California, most refined petroleum products (gasoline,
diesel fuel, motor oil, grease, coolant, etc.) have chemical constituents that are considered
to be hazardous waste. As such, the indiscriminate dumping or spillage of these fluids
onto the ground may constitute a misdemeanor, punishable by fines and/or imprisonment,
and shall not be allowed.
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Leighton and Associates,Inc.
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
Page30f6
3.0
3030.1094
2.2 Processing: Existing ground that has been declared satisfactory for support of fill by the
Geotechnical Consultant shall be scarified to a minimum depth of 6 inches. Existing
ground that is not satisfactory shall be overexcavated as specified in the following section.
Scarification shall continue until soils are broken down and free of large clay lumps or
clods and the working surface is reasonably uniform, flat, and free of uneven features that
would inhibit uniform compaction.
2.3 Overexcavation: In addition to removals· and overexcavations recommended 'in the
approved geotechnical report(s) and the grading plan, soft, loose, dry, saturated, spongy,
, ....... , ' organic-rich, highly,'fractured or otherwise unsuitable ground .shall be .overexcavated to
· competent ground as evaluated by the Geotechnical Consultant during grading.
2.4 . Benching: Where fills. are to.be placed on 'ground with slopes steeper than 5:1 (horizontal
· to vertical units), the ground shall be stepped or benched. Please see the Standard Details
for a graphic illustration. The lowest bench or key shall be a 'minimum of 15 feet wide and
at least 2 feet deep, into competent material as evaluated by·the Geotechnical Consultant ..
Other benches shall be excavated a minimum height of 4 feet into competent material or as
otherwise recommended by the Geotechnical Consultant. Fill placed on ground sloping
flatter than 5: 1 shall also be benched or otherwise overexcavated to provide' a flat subgrade
for the fill.
2.5 Evaluation! Acceptance of Fill Areas: All areas to receive fill, including removal and
processed areas, key bottoms, and benches, shall be observed, mapped, elevations
recorded, and/or tested prior to being accepted by the Geotechnical Consultant as suitable
to receive fill. The Contractor shall obtain a -written acceptance from the Geotechnical
' .. ,'. :' . .-' :'Consultant prior to' fil.! placement. 'A licensed surveyor shall provide the survey control for
determining elevations of processed areas, keys, and benches.
Fill Material
3.1
3.2
General: . Material to be used as fill shall be essentially free of organic matter and other
deleterious' substances' evaluated' and . accepted by the Geotechnical Consultant prior to
placement. Soils of poor· quality,· such ... as those .. with,:unaccepta:ble gradation, high·
expansion potential, or low strength shall be placed in 'areas acceptable to the Geotechnical
Consultant or mixed with other soils to achieve satisfactory fill material.
Oversize: Oversize material defined as rock, or other irreducible material with a maximum
dimension greater than 8 inches, shall not· be buried or placed in fill unle~s location,
· materials, and, placement methods" are. specifically accepted' by the' Geotechnical
Consultant. Placement operations shall be such that nesting of oversized material does not
occur and such that oversize material is completely surrounded by compacted or densified
fill. Oversize material shall not be placed within 10 vertical feet of finish grade or within
2 feet of future utilities or underground construction.
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Leighton and Associates, Inc.
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
Page4of6
3.3 Import: If importing of fill material is required for grading, proposed import material shall
meet the requirements of Section 3.1. The potential import source shall be gjven to the.
Geotechnical Consultant at least 48 hours (2 working days) before importing begins so that
its suitability can be determined and appropriate tests performed.
4 .. 0 Fill Placement and Compaction
4.1 Fill Layers: Approved fill material shall be placed in areas prepared to receive fill (per
Section.3.0) in near-horizontal layers not exceeding 8 inches. in loose thickness. The
Geotechnical Q:msultant may' accept thicker layers if testing indicates the grading
procedures can adequately compact the thicker layers. Each layer shall be spread' evenly .
,and mixed thoroughly to attain relative uniformity of material and moisture throughout.
.' 4.2 _ .Fill Moisture Conditioning; Fill soils shall be watered; dried back; blended, and/or mixed,
as necessary to attain a relatively uniform moisture content at or slightly over optimum .
. Maximum -:density and optimum. soil moisture content· tests shall be performed in
accordance with the American Society of Testing and Materials (ASTM Test Method.
D1557-91).
.. ' 4.3 ' .. ". Compactioll'of Fill: After each layer has been moisture-conditioned;mixed, and' evenly
spread, it shall be uniformly compacted to not less than 90 percent of maximum dry density
(ASTM Test Method D 15 57-91). Compaction equipment shall be adequately sized and be
either specifically designed for soil compaction or of proven reliability to efficiently
achieve the specified level of compaction with uniformity.
3030.1094
4.4 Compaction ofFill Slopes: In addition to normal compaction procedures specified above,
. compaction of slopes' shall be accomplished by backrolling of slopes with sheepsfoot
.. rollers. at .increments of 3 . to 4 feet in. fill elevation, or by other methods producing
satisfactory results acceptable to . the Geotechnical Consultant. Upon completion of
grading, relative. compaction of the fill, out to the slope face, shall be at least 90 percent of
maximum density per ASTMTestMethod DI557-91.
. 4.5 Compaction Testing: Field tests Jor.moisture·.content and:relative compaction of the fill
soils shall be performed by the Geotechnical Consultant. Location and frequency of tests
shall be at the Consultant's discretion based on field conditions encountered. Compaction
test locations will not necessarily be selected on a random basis. Test locations shall be
selected to verify adequacy of compaction levels in areas that are judged to be prone to
inadequate compaction (such as close to slope faces and at the fill/bedrock benches).
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Leighton and Associates,Inc.
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
PageS of6
4.6 Frequency of Compaction Testing: Tests shall be taken at intervals not exceeding 2 feet in
vertical rise andl or 1,000 cubic yards of compacted fill soils embankment. In addition, as a
guideline, at least one test shall be taken on slope faces for each 5,000 square feet of slope
face andlor each 10 feet of vertical height of slope. The Contractor shall assure that fill
construction is such that the testing schedule can be accomplished bY'the Geotechnical
Consultant. The Contractor shall stop or slow down the earthwork construction if these .
minimum standards are not met.
'. A.7 ,CompactionTestLocations: The Geotechnical Consultant shall documentthe approximate
....... elevation and horizontal coordinates of each test.1ocation .. The Contractor shall coordinate
with the project surveyor to assure that sufficient grade stakes are established so that tlle
Geotechnical Consultant can determine the test locations with. sufficient accuracy. At a
minimum, two grade stakes within a horizontal distance. of 100 feet and vertically less than
5 feet apart from potential test locations shall be provided.
5.0 Sub drain Installation
Subdrain systems shall'be installed in' accordance' with the approved geotechnical report(s), the
..... _ grading plan, and the Standard Details .. The Geotechnical Consultant may recommend additional .
, . ':-' " subdrains and/or changes'in subdraiIi extent, 'location, grade, or 'material depending on' conditions
6.0
3030.1094
encountered during grading. All subdrains shall be surveyed by a land surveyor/ciVil engineer for
line and grade after installation and prior to burial. Sufficient time should be ~lowed by the
Contractor for these surveys.
Excavation
. Excavations, as well as over-excavation for remedial purposes, shall be evaluated by the
Geotechnical Consultant during grading. Remedial removal depths shown on geotechnical plans
.are .estimates only. The actual extent of removal shall be determined by the Geotechnical
Consultant based on the field evaluation of exposed conditions during grading. Where fill-over-cut
. slopes are to be graded, the cut portion of the slope shall be made, evaluated, and accepted by the
Geotechnical Consultant prior to placement of materials 'for . construction, of the fill portion of the
slope, unless otherwise recommended by the Geotechnical Consultant
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Leighton and Associates, Inc.
GENERAL EARTHWORK AND GRADING SPECIFICATIONS
Page 6 bf6
7.0 Trench Backfills
3030.1094
7.1 The Contractor shall follow all OHSA and Cal/OSHA requirements for safety of trench
excavations.
7.2 All bedding and backfill of utility trenches shall be done in accordance with the applicable
. provisions of Standard Specifications of Public Works Construction. Bedding. material
shall have a Sand Equivalent greater than 30 (SE>30). The bedding shall be placed to 1
foot over the top of the conduit and densified by jetting. Backfill shaH be placed and
·densified·to a minimum of 90 percent of maximum from. 1 foot above the top of the
conduit to the surface.
-7.3 --. The jetting· of the··bedding around .the conduits-shall, be·!observed-.by."the. Geotechnical
Consultant.
7.4 The Geotechnical Consultant shall test the trench backfill for relative compaction. At least
one test should be made for every 3 00 feet of trench and 2 feet of fill.
Lift thickness of trench backfill shall not exceed those allowed in the Standard
Specifications of Public Works .Construction unless the.Contractor can demonstrate to the
Geotechnical. Consultant that the fill lift can be compacted to the minimum relative
compaction by his alternative equipment and method.
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,--------2' MIN.
KEY DEPTH
CUT FACE
SHALL' BE CONEJTRUCTED PRIOR
TO FILL PLACEMENT' TO ASSURE '~TE GEOLOGIC CONOITIONS
PROJECTED PlANE
, 1 TO 1 MAXIMUM FROM
TOE OF SLOPE TO
APPROVED GROUNO
2' MIN.
KEY DEPTH
OVERBUILT AND
TRIM BACK
KEYING AND BENCHING
REMOVE ,UNSUrr~ ,
MATERIAL
FILL SLOPE
'. "FILl.-OVEa-CUT .' .
SLOPE'
CUT-OVER-FILL
SLOPE
For Subdrains See"
Standard, Detail C
GENERAL EARTHWORK AND GRADING m[JJ' SPECIFICAnONS ~ '~
STANDARD DETAILS' A
REV.,04111198
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FINISH GRADE
SLOPE ___ -: - - _ :!O'-MIN.---~O~'!A£TJ:D F~:=E:" :'
FACE ---=--=--=----=--=---:..----=-------f --------=-.;...--------:..--=-----------:: ..... --= --------,.--.---------~----------:;.~--------n--, -a---""'::::=-::::.:-.z:-=-:~-::=-:-=-: . -:..:--~:-::--,-:-::~ ---:..---:..--=----=-+---=---=--=-----..... -------,0;: --------.... ------:-.... - ---:.----~--:-:-"7! :=:~:--::?-:-:::, =:--=-:-:=~= . ::~-:.: -------------"7"--0-------------n--·----:-------n----:----=--=--~---:.. _ _-_-_-_-:..-_-..z:...-_-_ -_-.:.:-_~ -_-.;,..-_-:..-.;,..-:..-_-==-...,.._-:..-:..-_-_-...:-
--=-----=-------~------...;;:..-:..-=----..::.. -----:..---=-~-0'-:..-:..---=---..... --0' MIN'--:.:z:--=------------~--------------. ---I ~~~----------------------_----~--_-. _-__ :~ ~~_-:--__ -~---=-: ::4:"~N.:-:-_JS'.!'IN;:,;.. : -: :-_~_ -'
,---.e: ___ .;,..-_-_-:..-_=__-_--5]-------=-----:..--D-~-----=-----------..::-----~...:-----:· -------------------------------------=---...:-_---_-:..-..;....:-y------:..----------------...:-_--=-...:--=-----..:-_-------...:---..::.-=...-:..-_-=--_-_-_-.r--=--_-_""'":..-:.... __ --=--_-_-_--=-_-_-_--:.._-::..-_-__ -_-_-_-::-_-:::..-_-_-_-_--.:.-_--.
::--. -==~:-OVERSIZE -: --~=-?=:=-:::--::--:=-:--:-~--:.~-JElTED OR FLOODED : _7 :--::WINDROW =--:-:-:-:::--:::--:-:--..:---..::------GRANULAR MATERIAL -. ---------------
• Oversize rock Is larger than 8 inches
in largest dimension. '
• Excavate a trench in the compacted
fill deep enough to bury all the rock.
• Backfill with granular soil jetted or
flooded In place to fin all the voids.
• Do not bury rock within 10 feet of
'. , finish grade.
• Windrow of buried rock shall be
parallel to the finished slope fiU. ELEVATION A-A'
~ROFILE ALONG WINQROW '
JElTED OR FLOODED
GRANULAR MATERIAL
OVERSIZE
ROCK DISPOSAL
_A--_ --=--=-.' - -
GENERAL EARTHWORK ANO GRADING mmn SPECifiCATIONS ~ u
STANDARD DETAILS S'
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NATURAL
~GROUND ",.
BENCHING _--fill'" REMOVE .,r=.....,.. __ UNSUITABLE
MATERIAL
CAL TRANS CLASS II
PERMEABLE OR #2 ROCK
(9FT.3/FT.) WRAPPED IN
FILTER FABRIC
FILTER FABRIC .
:=~~~ OR"COLLECTOR'PIPE SHALL
EQUIVALENT) BE MINIMUM 6· DIAMETER .
SCHEDULE 40 PVC PERFORATED CANYON SUBDRAIN OUTLET DETAIL PIPE. SEE STANDARD DETAIL D
DESIGN.
FINISHED
GRADE
PERFORATED PIPE 6-. MIN.
-
~20'MIN'~
NON·PERFORATED 5' MIN. 6-. MIN.
CANYON SUBDRAINS
FOR PIPE SPECIFICATION
·FILTER FABRIC
(MIRAFI 140 OR
APPROVED
EQUIVALENT)
#2 ROCK WRAPPED IN FILTER
FABRIC OR CALTRANS CLASS II
PERMEABLE.
GENERAL EARTHWORK AND GRADI,NG Dfj~"[TI
SPECIFICATIONS ~ u
STANDARD DETAILS C '
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OUTLET· PIPES 4-. NON.PERFO~ TED PIPE,
100' MAX. O.C. HORIZONTALLY,
30' MAX. O.C. VERTICALLY
--------------
---r __ BACKCUT 1:1
-"--OR FLATTER
--=--------------=--=----....:-~ I --=--:::-:, --=--:-=-~=:-=---..;: .,,~ ."; " ..... '''\.~ ..... " .... " ...... . ----------------.,------------------------_ ....... _---=----=------=--=-----_-:.:-_-_-_T_ .
---------------/ . -------- --------\
. ---------------KEY 1'+ _-:::-::===-:=:-~_ --=-:==--:z: ~ . ~EPTH L ---=----------::-~~=:=_=:-_ "
• I!~>"'~' -----------:...-------=----=--=--=--=--- \ . ~ \ .-···-------r~·· ------------------:;z: ~
2' ~I~. I~~~-:-:-~;~~:N·-=;:~-:::T --\. /~OVER'w FROM TlfE T9P
KEY WIDTH POSITIVE SEAL . ,HOG RING nED EVERY 6 F'EET
SHOULD BE 'C \ "
PROVIDED AT \ FILTER FABRIC
THE JO~ . .,,/'\ -.: (MIRAF11400R S" At .• .APPROVED
OUTLET PIPE . IN~-; EQUIVALENl) (NON.PERFORATED)-';~ J
. \ T -CONNECnON .fOR
CAL TRANS CLASS Ii COLLECTOR PIPE TO
PERMEABLE OR #2 ROCK , . OUTLET' PIPE
(3FT.3/FT.) WRAPPED IN ~ , . ./
FILTER FABRIC ~'
• SUBDRAIN INSTALLATION· Subdraih collector pipe shall be Installed with perfOrations down or,
unless otherwise designated by the geotechnical consultant. Outlet pipes shall be non-perforated
pipe. The subdrain pipe shall have at least 8 perforations uniformly spaced per foot •. Perforation shall
be iA· to 1f.a. if drilled holes are used. All subdrain pipes shall have.a gradient ~ least 2% towards the
, outlet.
• SUBDRAIN PIPE -Subdrain pipe shall be ASTM 02751, SOR 23.5 or ASTM 01527, Schedule 40, or
ASTM 03034, SOR 23:5, Sched~le 40 Polyvinyl Chloride Plastic (PVC) pipe.
• All outlet pipe shall be placed in a trench no wider than twice the subdrain pipe; Pipe shall be in soil
of SE>30 jetted or flooded in place except for the outside 5 feet which shall be native SOil backfill.
BUTTRESS OR
REPLACEMENT FILL
SUBDRAINS .
GENERAL EARTHWORK AND GRADING
SPECIFICATIONS
STANDARD DETAILS D