HomeMy WebLinkAboutCT 04-08; La Costa Village Townhomes; Soil Analysis; 2011-07-14RECORD COPY
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UPDATE
GEOTECHNICAL INVESTIGATION
LA COSTA VILLAGE TOWNHOMES
(CARLSBAD 3), CT 04-08
DOVE LANE AND EL CAMINO REAL
CARLSBAD, CALIFORNIA
PREPARED FOR
CITY VENTURES
SANTA ANA, CALIFORNIA
APRIL 25, 2011
REVISED JULY 14, 2011
PROJECT NO. 07193-32-03
GEOCON
INCORPORATED
GEOTECHNICAL • ENVIRONMENTAL • MATERIALS
Project No. 07193-32-03
April 25,2011
Revised July 14, 2011
City Ventures
2850 Red Hill Avenue, Suite 200
Santa Ana, Califomia 92750
Attention: Mr. Tony Pauker
Subject: UPDATE GEOTECHNICAL INVESTIGATION
LA COSTA VILLAGE TOWNHOMES (CARLSBAD 3), CT 04-08
DOVE LANE AND EL CAMINO REAL
CARLSBAD, CALIFORNIA
Dear Mr. Pauker:
In accordance with your request, we are providing this revised update geotechnical investigation after
receiving plan check comments from the City of Carlsbad for the La Costa Village Townhomes
(Carlsbad 3) project located northwest of the intersection of Dove Lane and El Camino Real in the
City of Carlsbad, Califomia. A previous geotechnical report was prepared for the property by Geocon
Incorporated and we understand that a new site development plan is being submitted which is
essentially the same from a geotechnical perspective as the prior plan.
Based on our review of the previous Geocon report, new site grading plan, and observations during a
recent site visit to the property, it is our opinion that the site is suitable for development provided the
recommendations of this report are followed.
Should you have any questions regarding this update report, or if we may be of further service, please
contact the undersigned at your convenience.
Very tmly yours,
GEOCONINCORPORATED
Trevor E. Myers
RCE 63773
TEM:DBE:dmc
(email) Addressee
(3/del) C&V Consulting
Attention: Mr. Daryl Kessler
6960 Flanders Drive • San Diego, California 92121-2974 • Telephone 858.558.6900 • Fax 858.558.6159
TABLE OF CONTENTS
1. PURPOSE AND SCOPE 1
2. SFFE AND PROJECT DESCRIPTION 1
3. SOIL AND GEOLOGIC CONDiriONS 2
3.1 Previously Placed Fill (Qpf) 2
3.2 Topsoil (Unmapped) 2
3.3 Alluvium/CoUuvium Undifferentiated (Qal/Qcol) 2
3.4 Terrace Deposit (Qt) 3
3.5 Santiago Formation (Tsa) 3
4. GROUNDWATER 3
5. GEOLOGIC HAZARDS 4
5.1 Faulting and Seismicity 4
5.2 Landslides 6
5.3 Soil Liquefaction Potential 6
5.4 Tsunamis and Seiches 6
6. CONCLUSIONS AND RECOMMENDATIONS 7
6.1 General 7
6.2 Excavation and Soil Characteristics 7
6.3 Slopes 8
6.4 Grading 9
6.5 Seismic Design Criteria 10
6.6 Foundation and Concrete Slabs-On-Grade Recommendations 11
6.7 Retaining Walls and Lateral Loads 16
6.8 Geogrid-Reinforced Retaining Walls 18
6.9 Preliminary Pavement Recommendations 19
6.10 Stormwater Management 23
6.11 Site Drainage and Moisture Protection 23
6.12 Grading and Foundation Plan Review 24
LIMFT ATIONS AND UNIFORMIIY OF CONDmONS
MAPS AND ILLUSTRATIONS
Figure 1, Vicinity Map
Figure 2, Geologic Map
Figure 3, Slope Stability Analysis
Figure 4, Surficial Slope Stability Analysis
Figure 5, Wall/Column Footing Dimension Detail
Figure 6, Typical Retaining Wall Drain Detail
APPENDDC A
FIELD INVESTIGATION
Figures A-1 - A-10, Logs of Trenches (Project No. 06432-22-01)
TABLE OF CONTENTS (Continued)
APPENDIX B
LABORATORY TESTING (Project No. 06432-22-01)
Table B-I, Summary of Remolded Direct Shear Test Results
Table B-IL Summary of Laboratory Expansion Index Test Results
Table B-in, Summary of Laboratory Maximum Dry Density and Optimum Moisture Content Tests Results
Table B-FV, Summary of Laboratory Resistance Value Test Results
APPENDDC C
RECOMMENDED GRADING SPECIFICATIONS
LIST OF REFERENCES
UPDATE GEOTECHNICAL INVESTIGATION
1. PURPOSE AND SCOPE
This report updates previous documents prepared for the property and provides site-specific
recommendations for development of the Moonstone (Carlsbad 3) Project, a proposed residential
project located northwest of the intersection between Dove Lane and El Camino Real, in the City of
Carlsbad, Califomia (see Vicinity Map, Figure 1). The purpose of the investigation was to describe
site geology and subsurface soil conditions based on previous exploratory trenching and laboratory
testing conducted on the property, and based on conditions encountered, provide recommendations
relative to geotechnical aspects of developing the property as proposed.
The scope of our investigation included a site reconnaissance and review of the following report and
plan:
1. Update Geotechnical Investigation, Levatino Property, Carlsbad, Califomia, prepared by
Geocon Incorporated dated January 25, 2007 (Project No. 07193-42-02).
2. Precise Grading Plan For: La Costa Village Townhomes, Carlsbad, Califomia, prepared by
C&V Consulting, Inc., undated (Project No. CT-04-08, Drawing No. 471-6A).
The above-referenced geotechnical investigation included subsurface studies performed during a field
investigation conducted on December 13, 1999 that consisted of excavating ten backhoe trenches.
The approximate locations of the trenches from the Geocon, January 5, 2000 report have been
replotted on a copy of the above-referenced site plan (see Figure 2). Logs of exploratory trenches and
other details associated with our previous geotechnical report are presented in Appendix A.
Laboratory tests were perfonned on selected soil samples obtained from the trenches to evaluate their
pertinent physical properties for engineering analyses. A discussion pertaining to laboratory testing
and test results is presented in Appendix B.
Recommendations presented herein are based on analysis of data obtained from previous exploratory
trenches, laboratory tests, and our experience with similar soil and geologic conditions.
2. SITE AND PROJECT DESCRIPTION
The site consists of an approximately 14-acre trapezoidal parcel of undeveloped land situated at the
northwest comer of the intersection of El Camino Real and Dove Lane in the City of Carlsbad,
California (see Vicinity Map, Figure 1). Presently the site is covered by native bmsh. Elevations on
the property range from a high of approximately 275 feet above mean sea level (MSL) at the northem
end to a low of approximately 180 feet MSL in a drainage basin along Dove Lane. A portion of site
mnoff is detained in two existing desilting basins at the southem end of the property.
Project No. 07193-32-03 - I - April 25, 2011
Revised July 14, 2011
Review of the referenced site plan indicates development will occur only within the southem
approximately one-third of the property. Development will include site grading to constmct 13
building pads for support of townhome buildings comprising approximately 53 units. Access to the
buildings will be via a private driveway off Dove Lane. Grading is anticipated to consist of cuts on
the order of 15 feet along El Camino Real and fills of up to 25 feet along Dove Lane. Foundation
support will likely be provided by conventional shallow continuous footings and/or spread footings
with slab-on-grade floors. Several retaining walls, typically 5 to 6 feet in height, are planned along
the perimeter of the site. Below the fill slope along Dove Lane, two stacked walls will be constmcted.
The walls may consist of keystone earth reinforced walls. Numerous auto parking spaces and four
recreational vehicle parking areas are planned. Both active and passive recreation areas will be
constmcted.
3. SOIL AND GEOLOGIC CONDITIONS
The field investigation indicated the site is underlain by three surficial soil types and two formational
units, which are described below in order of increasing age. Mapped geologic conditions are depicted
on the Geologic Map (Figure 2, map pocket).
3.1 Previously Placed Fill (Qpf)
Previously placed fill soils are present along the northeast edge of the site paralleling El Camino Real
and along the southwestem and westem edges of the site. Most of the fill located in lower elevation
areas and arroyos are canyon fills related to road constmction and pipeline easements of El Camino
Real or Dove Lane. Estimated thickness of the fill is on the order of 5 feet or more. All previously
placed fill is undocumented and is considered to be compressible, requiring removal and
recompaction prior to fill placement and/or constmction of proposed site improvements.
3.2 Topsoil (Unmapped)
Topsoil was encountered in all the exploratory trenches to depths ranging from 1 to 2 feet. Topsoils
are indistinguishable from alluvium or colluvium and are characterized as soft, dry, sandy silt. The
topsoil is not adequate in its present condition for support of stmctures or stmctural fill.
3.3 Alluvlum/Colluvium Undifferentiated (Qal/Qcol)
Alluvial and colluvial soils are undifferentiated and are present in the lower elevation areas in the
southwest portions of the property. These soils were encountered in one of the exploratory trenches
(T-10). The alluvium/colluvium consists of at least 2 to 3 feet of loose silty sand. However, the depth
could be up to approximately 5 feet within the low areas of the drainage along Dove Lane and in the
Project No. 07193-32-03 - 2 - April 25, 2011
Revised July 14, 2011
southeast portion paralleling El Camino Real (see Figure 2, Geologic Map). The alluvium/colluvium
is not suitable in its present condition for support of stmctures and/or stmctural fill. Removal and
recompaction of alluvium should be performed as recommended under the Grading section of this
report.
3.4 Terrace Deposit (Qt)
Terrace deposits consisting of medium-dense to dense, clayey fine sands were mapped in the northem
portion of the property. These soils cap the Santiago Formation sandstones at elevations
approximately above 240 feet MSL. The terrace deposits are considered suitable for foundation
and/or fill support in their present condition. However, this unit is not anticipated to be encountered
during grading as development is proposed only on the southem portions of the property.
3.5 Santiago Formation (Tsa)
Santiago Formation was encountered beneath the topsoil and alluvium in all the exploratory trenches
at depths ranging from 1 to 3 feet. The Santiago Formation at this location is characterized by very
dense, silty sandstone and very hard sandy siltstone. Dipping bedding was observed in the Santiago
Formation in some of the exploratory trenches. However, bedding is typically horizontal across the
majority of the site. An engineering geologist should observe all cut slopes during grading to
determine the presence or absence of adverse geology.
The formational materials are adequate in their present condition for support of proposed stmctures
and stmctural fills. Some difficulty of excavation may be encountered in the formational materials if
cemented zones are encountered.
4. GROUNDWATER
Groundwater was not encountered in any of the exploratory trenches during the previous field
investigation. However, surficial soils and the upper portion of formational materials in the drainage
basin along Dove Lane were found to be wet. Removal of wet compressible soil in the drainage
basin, if required, may require localized dewatering and/or special equipment or grading techniques
to efficiently excavate and recompact unsuitable material.
Groundwater is not expected to adversely impact project development as presently proposed. In
addition, stormwater infiltration BMP's are not planned that could induce seepage migration.
However, it is not uncommon for groundwater or seepage conditions to develop where none
previously existed. Proper surface drainage of irrigation and rainwater will be critical to future
performance of the project.
Project No. 07193-32-03 - 3 - April 25, 2011
Revised July 14, 2011
5.1
5. GEOLOGIC HAZARDS
Faulting and Seismicity
A review of the referenced geologic materials and our knowledge of the general area indicate that the
site is not underlain by active, potentially active, or inactive faults. An active fault is defined by the
California Geological Survey (CGS) as a fault showing evidence for activity within the last
11,000 years. The site is not located within State of Califomia Earthquake Fault Zone.
According to the computer program EZ-FRISK (Version 7.51), 11 known active faults are located
within a search radius of 50 miles from the property. The nearest known active fault is the Rose
Canyon Fault, located approximately 6 miles west of the site and is the dominant source of potential
ground motion. Earthquakes that might occur on the Rose Canyon Fault Zone or other faults within
the southem Califomia and northem Baja Califomia area are potential generators of significant
ground motion at the site. The estimated deterministic maximum earthquake magnitude and peak
ground acceleration for the Rose Canyon Fault are 7.2 and 0.34g, respectively. Table 5.1.1 lists the
estimated maximum earthquake magnitude and peak ground acceleration for the most dominant faults
in relationship to the site location. We calculated peak ground acceleration (PGA) using Boore-
Atkinson (2008) NGA USGS2008, Campbell-Bozorgnia (2008) NGA USGS, and Chiou-Youngs
(2008) NGA acceleration-attenuation relationships.
TABLE 5.1.1
DETERMINISTIC SPECTRA SITE PARAMETERS
Fault Name
Distance
from Site
(miles)
Maximum
Earthquake
Magnitude
(Mw)
Peak Ground Acceleration
Fault Name
Distance
from Site
(miles)
Maximum
Earthquake
Magnitude
(Mw)
Boore-
Atkinson
2008 (g)
Campbell-
Bozorgnia
2008 (g)
Chiou-
Youngs
2008 (g)
Rose Canyon 6 7.2 0.27 0.27 0.34
Newport-Inglewood (offshore) 10 7.1 0.21 0.19 0.23
Coronado Bank 22 7.6 0.16 0.12 0.15
Elsinore (Julian) 24 7.1 0.12 0.09 0.10
Elsinore (Temecula) 24 6.8 0.11 0.08 0.08
Elsinore (Glen-Ivy) 37 6.8 0.07 0.06 0.05
Earthquake Valley 40 6.5 0.05 0.05 0.03
San Joaquin Hills 41 6.6 0.06 0.06 0.05
Palos Verdes 41 7.3 0.08 0.06 0.07
San Jacinto (Anza) 47 7.2 0.07 0.05 0.05
San Jacinto (San Jacinto Valley) 48 6.9 0.06 0.05 0.04
Project No. 07193-32-03 April 25, 2011
Revised July 14, 2011
We used the computer program EZ-FRISK to perform a probabilistic seismic hazard analysis. The
computer program EZ-FRISK operates under the assumption that the occurrence rate of earthquakes
on each mappable Quatemary fault is proportional to the faults slip rate. The program accounts for
fault mpture length as a function of earthquake magnitude, and site acceleration estimates are made
using the earthquake magnitude and distance from the site to the mpture zone. The program also
accounts for uncertainty in each of following: (1) earthquake magnitude, (2) mpture length for a
given magnitude, (3) location of the mpture zone, (4) maximum possible magnitude of a given
earthquake, and (5) acceleration at the site from a given earthquake along each fault. By calculating
the expected accelerations from considered earthquake sources, the program calculates the total
average annual expected number of occurrences of site acceleration greater than a specified value.
We utilized acceleration-attenuation relationships suggested by Boore-Atkinson (2008) NGA USGS,
Campbell-Bozorgnia (2008) NGA USGS, and Chiou-Youngs (2008) in the analysis. Table 5.1.2
presents the site-specific probabilistic seismic hazard parameters including acceleration-attenuation
relationships and the probability of exceedence.
TABLE 5.1.2
PROBABILISTIC SEISMIC HAZARD PARAMETERS
Probability of Exceedence
Peak Ground Acceleration
Probability of Exceedence Boore-Atkinson,
2007 (g)
Campbell-Bozorgnia,
2008 (g)
Chiou-Youngs,
2008 (g)
2% in a 50 Year Period 0.49 0.48 0.59
5% in a 50 Year Period 0.36 0.35 0.43
10% in a 50 Year Period 0.28 0.27 0.32
The Califomia Geologic Survey (CGS) has a program that calculates the ground motion for a
10 percent of probability of exceedence in 50 years based on an average of several attenuation
relationships. Table 5.1.3 presents the calculated results from the Probabilistic Seismic Hazards
Mapping Ground Motion Page from the CGS website.
TABLE 5.1.3
PROBABILISTIC SITE PARAMETERS FOR SELECTED FAULTS
CALIFORNIA GEOLOGIC SURVEY
Calculated Acceleration (g)
Firm Rock
Calculated Acceleration (g)
Soft Rock
Calculated Acceleration (g)
Alluvium
0.26 0.28 0.32
Project No. 07193-32-03 April 25, 2011
Revised July 14, 2011
While listing peak accelerations is useful for comparison of potential effects of fault activity in a
region, other considerations are important in seismic design, including the frequency and duration of
motion and the soil conditions underlying the site. Seismic design of the stmctures should be
evaluated in accordance with the Califomia Building Code (CBC) guidelines currently adopted by the
CityofCarlsbad.
5.2 Landslides
No landslides were encountered during the site investigation, and none are known to exist on the
property or at a location that would impact the site.
5.3 Soil Liquefaction Potential
Soil liquefaction occurs within relatively loose, cohesionless sands located below the water table that
are subjected to ground accelerations from earthquakes. None of the trenches encountered
groundwater, and the loose topsoil and alluvium encountered in the trenches will be removed and
recompacted. Formational materials were found to be dense to very dense. Therefore, the potential for
liquefaction occurring at the site is considered very low.
5.4 Tsunamis and Seiches
The site is not located near the ocean or any other large bodies of water, so there is no risk of
tsunamis or seiches affecting the site.
Project No. 07193-32-03 - 6 - April 25, 2011
Revised July 14, 2011
6. CONCLUSIONS AND RECOMMENDATIONS
6.1 General
6.1.1 No soil or geologic conditions were encountered during previous studies and none were
observed during our recent site reconnaissance that would preclude development of the
project as proposed. From a geotechnical standpoint, it is our opinion that the site is
suitable for development provided the recommendations presented herein are implemented
in design and constmction of the project.
6.1.2 The site is underlain by shallow topsoil, alluvium/colluvium, and terrace deposits over
Tertiary-age Santiago Formation. Topsoil and alluvium/colluvium within planned grading
limits should be removed and replaced as compacted fill prior to placing additional fill
and/or stmctural improvements.
6.1.3 Subsurface conditions observed in our trenches are expected to be fairly consistent across
the site and may be extrapolated to reflect general soil and geologic conditions; however,
some variations in subsurface conditions between trench locations should be anticipated.
6.1.4 Groundwater was not encountered in any of the backhoe trenches. During grading,
groundwater or seepage (if encountered) should be observed by an engineer and/or
engineering geologist to determine whether remedial recommendations are required.
Groundwater and/or seepage-related problems are not anticipated if surface drainage is
directed into properly designed drainage stmctures and away from pavement edges,
buildings and other moisture-sensitive developments.
6.1.5 With the exception of possible strong seismic shaking, significant geologic hazards were
not observed or are known to exist on the site that could adversely impact proposed
development.
6.2 Excavation and Soil Characteristics
6.2.1 The soil encountered in the field investigation is considered to be "expansive" (expansion
index [EI] of greater than 20) as defined by 2010 Califomia Building Code (CBC)
Section 1803.5.3. Table 6.2 presents soil classifications based on the expansion index. A
majority of the soil encountered is planned to possess a "low" to "medium" expansion
potential (expansion index of 90 or less).
Project No. 07193-32-03 -7- April 25, 2011
Revised July 14, 2011
TABLE 6.2
SOIL CLASSIFICATION BASED ON EXPANSION INDEX
Expansion Index (EI) Soil Classification
0-20 Very Low
21-50 Low
51-90 Medium
91-130 High
Greater Than 130 Very High
6.2.2 The on-site surficial soils can be excavated with a light to moderate effort using
conventional heavy-duty equipment. A moderate to heavy effort will likely be required to
efficiently excavate the Santiago Formation. Cemented zones within the formational
materials could be difficult to excavate and, if encountered, will result in generation of
oversize rock fragments.
6.2.3 It is the responsibility of the contractor to ensure that all excavations and trenches are
properly shored and maintained in accordance with applicable OSHA mles and regulations
in order to maintain safety and maintain the stability of adjacent existing improvements.
6.3 Slopes
6.3.1 Slope stability analysis utilizing average drained, direct shear strength parameters, based on
laboratory tests and experience with similar soil types, indicates that proposed cut slopes
and fill slopes constmcted with on-site soils will have calculated factors of safety in excess
of 1.5 under static conditions for both deep-seated failure and shallow sloughing
conditions. Slope stability analyses are presented on Figures 3 and 4.
6.3.2 It is recommended that all cut slope excavations be observed by an engineering geologist to
evaluate if soil and geologic conditions are as described in this report and do not differ
significantly from those anticipated.
6.3.3 The outer 15 feet (or a distance equal to the height of the slope, whichever is less) of fill
slopes should consist of properly compacted granular soil fill to reduce the potential for
surface sloughing. All fill slopes should be compacted by back-rolling at vertical intervals
not to exceed 4 feet and should be track-walked upon completion such that the fill soils are
uniformly compacted to at least 90 percent relative compaction to the face of the finish
slope.
Project No. 07193-32-03 April 25, 2011
Revised July 14,2011
6.3.4 All slopes should be landscaped with drought-tolerant vegetation, having variable root
depths and requiring minimal landscape irrigation. In addition, all slopes should be drained
and properly maintained to reduce erosion.
6.4 Grading
6.4.1 Grading should be performed in accordance with the Recommended Grading Specifications
in Appendix C. Wliere the recommendations of this report conflict with those in
Appendix C, the recommendations of this section take precedence.
6.4.2 Earthwork should be observed and compacted fill tested by representatives of Geocon
Incorporated.
6.4.3 A preconstmction conference should be held at the site prior to the beginning of grading
operations with the developer, grading contractor, civil engineer, and soil engineer in
attendance. Special soil handling requirements can be discussed at that time.
6.4.4 Grading of the site should commence with removal of existing vegetation and existing
improvements from areas to be graded. Deleterious debris such as wood, asphalt and
concrete should be exported from the site and should not be mixed with fill soil. All
existing underground improvements within the proposed building areas should be removed
and the resulting depressions backfilled with properly compacted soil.
6.4.5 Topsoil, alluvium, colluvium, and previously placed fill within planned areas of grading
should be completely removed and recompacted. The depth of removal should be such that
material exposed at the base of the overexcavation consists of dense Santiago Formation.
6.4.6 Prior to placing fill, the exposed ground surface should be scarified, moisture conditioned,
and compacted. Soil generated from on-site excavations can be then placed and compacted
in layers to design finish grade elevations. All fill (including scarified ground surfaces and
backfill) should be placed in horizontal loose layers no thicker than will allow for adequate
bonding, moisture conditioned to a water content above optimum moisture content, and
compacted to at least 90 percent relative compaction, as determined by ASTM Test Method
D 1557-07.
6.4.7 Where fill slopes are to be constmcted, grading should begin with excavation of a fill slope
keyway as shown in Appendix C.
Project No. 07193-32-03 - 9 - April 25, 2011
Revised July 14, 2011
6.4.8 It is recommended that the cut portion of lots with a cut-fill transition be undercut and
replaced with properly compacted low expansive fill. The undercut should be to a depth of
at least 3 feet and extend at least 5 feet beyond the building pad limits on the cut site of the
transition and into the fill side of the transition a sufficient distance such that a minimum of
3 feet of fill exists on the entire pad.
6.4.9 Where dense/hard formational material is present at or near finish grade, consideration
should be given to undercutting the building pad to create favorable conditions for footing
and utility trench excavations. The lateral limits of the undercut should extend at least
5 feet beyond the building footprint. Deeper undercutting of street areas exposing hard
formational materials should be considered to facilitate the excavation of underground
utilities. If subsurface improvements or landscape zones are planned outside these areas,
consideration should be given to undercutting these areas as well.
6.4.10 Where practical, the upper 3 feet of all building pads (cut or fill) and 12 inches in pavement
areas should be composed of properly compacted or undisturbed formational "very low" to
"low" expansive soils. The more highly expansive fill soils should be placed in the deeper
fill areas and properly compacted. "Very low" to "low" expansive soils are defined as those
soils that have an Expansion Index of 50 or less.
6.4.11 Import fill soil should consist of granular materials with a "low" expansion potential (EI
less than 50) free of deleterious material and stones larger than 3 inches and have a
negligible sulfate exposure as defined by 2010 CBC Section 1904.3 and ACI 318-08
Sections 4.2 and 4.3. Geocon Incorporated should be notified of the import soil source and
should perform laboratory testing of import soil prior to its arrival at the site to evaluate its
suitability as fill material.
6.4.12 Temporary slopes may be excavated no steeper than 1:1 (horizontal:vertical) without
shoring, provided the top of the excavation is a minimum of 15 feet from the edge of
existing buildings and other improvements. Excavations steeper than 1:1 or closer than
15 feet from existing improvements should be shored in accordance with applicable OSHA
codes and regulations.
6.5 Seismic Design Criteria
6.5.1 We used the computer program Seismic Hazard Curves and Uniform Hazard Response
Spectra, provided by the USGS. Table 6.5 summarizes site-specific design criteria obtained
from the 2010 Califomia Building Code (CBC; Based on the 2009 Intemationai Building
Code [IBC]), Chapter 16 Stmctural Design, Section 1613 Earthquake Loads. The short
Project No. 07193-32-03 - 10- April 25,2011
Revised July 14, 2011
spectral response uses a period of 0.2 second. The building stmcture and improvements
should be designed using a Site Class C.
TABLE 6.5
2010 CBC SEISMIC DESIGN PARAMETERS
Parameter Value 2010 CBC Reference
Site Class C Table 1613.5.2
Spectral Response - Class B (short), Ss l.I61g Figure 1613.5(3)
Spectral Response - Class B (1 sec), S\ 0.438g Figure 1613.5(4)
Site Coefficient, FA 1.000 Table 1613.5.3(1)
Site Coefficient, Fy 1.362 Table 1613.5.3(2)
Maximum Considered Earthquake
Spectral Response Acceleration (short), SMS 1.161g Section 1613.5.3 (Eqn 16-36)
Maximum Considered Earthquake
Spectral Response Acceleration - (1 sec), SMI 0.596g Section 1613.5.3 (Eqn 16-37)
5% Damped Design
Spectral Response Acceleration (short), SDS 0.774g Section 1613.5.4 (Eqn 16-38)
5% Damped Design
Spectral Response Acceleration (1 sec), SDI 0.398g Section 1613.5.4 (Eqn 16-39)
6.5.2 Conformance to the criteria in Table 6.5 for seismic design does not constitute any kind of
guarantee or assurance that significant stmctural damage or ground failure will not occur if
a large earthquake occurs. The primary goal of seismic design is to protect life, not to avoid
all damage, since such design may be economically prohibitive.
6.6 Foundation and Concrete Slabs-On-Grade Recommendations
6.6.1 The following foundation recommendations are for proposed one- to three-story residential
stmctures. The foundation recommendations have been separated into three categories
based on either the maximum and differential fill thickness or Expansion Index. The
foundation category criteria are presented in Table 6.6.1.
TABLE 6.6.1
FOUNDATION CATEGORY CRITERIA
Foundation
Category
Maximum Fill
Thickness, T (Feet)
Differential Fill
Thickness, D (Feet) Expansion Index (EI)
I T<20 — EI<50
II 20<T<50 10<D<20 50<EI<90
III T>50 D>20 90<EI<130
Project No. 07193-32-03 - 11 -April 25,2011
Revised July 14, 2011
6.6.2 Final foundation categories for each building or lot will be provided after finish pad grades
have been achieved and laboratory testing of the subgrade soil has been completed.
6.6.3 Table 6.6.2 presents minimum foundation and interior concrete slab design criteria for
conventional foundation systems.
TABLE 6.6.2
CONVENTIONAL FOUNDATION RECOMMENDATIONS BY CATEGORY
Foundation
Category
Minimum Footing
Embedment
Depth (inches)
Continuous Footing
Reinforcement
Interior Slab
Reinforcement
I 12 Two No. 4 bars,
one top and one bottom
6 X 6 - 10/10 welded wire
mesh at slab mid-point
II 18 Four No. 4 bars,
two top and two bottom
No. 3 bars at 24 inches
on center, both directions
III 24 Four No. 5 bars,
two top and two bottom
No. 3 bars at 18 inches
on center, both directions
6.6.4 The embedment depths presented in Table 6.6.2 should be measured from the lowest
adjacent pad grade for both interior and exterior footings. The conventional foundations
should have a minimum width of 12 inches and 24 inches for continuous and isolated
footings, respectively. A typical wall/column footing dimension detail is shown as
Figure 5.
6.6.5 The concrete slab-on-grade should be a minimum of 4 inches thick for Foundation
Categories I and II and 5 inches thick for Foundation Category III. The concrete slabs-on-
grade should be underlain by 4 inches and 3 inches of clean sand for 4-inch thick and
5-inch-thick slabs, respectively. Slabs expected to receive moisture sensitive floor coverings
or used to store moisture sensitive materials should be underlain by a vapor inhibitor covered
with at least 2 inches of clean sand or cmshed rock. If cmshed rock will be used, the
thickness of the vapor inhibitor should be at least 10 mil to prevent possible puncturing.
6.6.6 As a substitute, the layer of clean sand (or cmshed rock) beneath the vapor inhibitor
recommended in the previous section can be omitted if a vapor inhibitor that meets or
exceeds the requirements of ASTM E 1745-97 (Class A), and that exhibits permeance not
greater than 0.012 perm (measured in accordance with ASTM E 96-95) is used. This vapor
inhibitor may be placed directly on properly compacted fill or formational materials. The
vapor inhibitor should be installed in general conformance with ASTM E 1643-98 and the
manufacturer's recommendations. Two inches of clean sand should then be placed on top
Project No. 07193-32-03 12-April 25, 2011
Revised July 14, 2011
of the vapor inhibitor to reduce the potential for differential curing, slab curl, and cracking.
Floor coverings should be installed in accordance with the manufacturer's
recommendations.
6.6.7 As an altemative to the conventional foundation recommendations, consideration should be
given to the use of post-tensioned concrete slab and foundation systems for the support of
the proposed stmctures. The post-tensioned systems should be designed by a stmctural
engineer experienced in post-tensioned slab design and design criteria of the Post-
Tensioning Institute (PTI), Third Edition, as required by the 2010 Califomia Building Code
(CBC Section 1808.6). Although this procedure was developed for expansive soil
conditions, it can also be used to reduce the potential for foundation distress due to
differential fill settlement. The post-tensioned design should incorporate the geotechnical
parameters presented on Table 6.6.3 for the particular Foundation Category designated.
The parameters presented in Table 6.6.3 are based on the guidelines presented in the PTI,
Third Edition design manual.
TABLE 6.6.3
POST-TENSIONED FOUNDATION SYSTEM DESIGN PARAMETERS
Post-Tensioning Institute (PTI),
Third Edition Design Parameters
Foundation Category Post-Tensioning Institute (PTI),
Third Edition Design Parameters I II III
Thornthwaite Index -20 -20 -20
Equilibrium Suction 3.9 3.9 3.9
Edge Lift Moisture Variation Distance, CM (feet) 5.3 5.1 4.9
Edge Lift, yM (inches) 0.61 1.10 1.58
Center Lift Moisture Variation Distance, CM (feet) 9.0 9.0 9.0
Center Lift, yM (inches) 0.30 0.47 0.66
6.6.8 Foundation systems for the lots that possess a foundation Category I and a "very low"
expansion potential (expansion index of 20 or less) can be designed using the method
described in Section 1808 of the 2010 CBC. If post-tensioned foundations are planned, an
altemative, commonly accepted design method (other than PTI Third Edition) can be used.
However, the post-tensioned foundation system should be designed with a total and
differential deflection of 1 inch. Geocon Incorporated should be contacted to review the
plans and provide additional information, if necessary.
6.6.9 The foundations for the post-tensioned slabs should be embedded in accordance with the
recommendations of the stmctural engineer. If a post-tensioned mat foundation system is
Project No. 07193-32-03 - 13-April 25,2011
Revised July 14, 2011
planned, the slab should possess a thickened edge with a minimum width of 12 inches and
extend below the clean sand or cmshed rock layer.
6.6.10 If the stmctural engineer proposes a post-tensioned foundation design method other than
PTI, Third Edition:
• The deflection criteria presented in Table 6.6.3 are still applicable.
• Interior stiffener beams should be used for Foundation Categories II and III.
• The width of the perimeter foundations should be at least 12 inches.
• The perimeter footing embedment depths should be at least 12 inches, 18 inches
and 24 inches for foundation categories I, II, and III, respectively. The embedment
depths should be measured from the lowest adjacent pad grade.
6.6.11 Our experience indicates post-tensioned slabs are susceptible to excessive edge lift,
regardless of the underlying soil conditions. Placing reinforcing steel at the bottom of the
perimeter footings and the interior stiffener beams may mitigate this potential. Current PTI
design procedures primarily address the potential center lift of slabs but, because of the
placement of the reinforcing tendons in the top of the slab, the resulting eccentricity after
tensioning reduces the ability of the system to mitigate edge lift. The stmctural engineer
should design the foundation system to reduce the potential of edge lift occurring for the
proposed stmctures.
6.6.12 During the constmction of the post-tension foundation system, the concrete should be
placed monolithically. Under no circumstances should cold joints be allowed to form
between the footings/grade beams and the slab during the constmction of the post-tension
foundation system.
6.6.13 Category I, II, or III foundations may be designed for an allowable soil bearing pressure of
2,000 pounds per square foot (psf) (dead plus live load). This bearing pressure may be
increased by one-third for transient loads due to wind or seismic forces.
6.6.14 Isolated footings, if present, should have the minimum embedment depth and width
recommended for conventional foundations for a particular foundation category. The use of
isolated footings, which are located beyond the perimeter of the building and support
stmctural elements connected to the building, are not recommended for Category III.
Where this condition cannot be avoided, the isolated footings should be connected to the
building foundation system with grade beams.
Project No. 07193-32-03 - 14- April 25, 2011
Revised July 14, 2011
6.6.15 For Foundation Category III, consideration should be given to using interior stiffening
beams and connecting isolated footings and/or increasing the slab thickness. In addition,
consideration should be given to connecting patio slabs, which exceed 5 feet in width, to
the building foundation to reduce the potential for future separation to occur.
6.6.16 Footings that must be placed within seven feet of the top of slopes should be extended in
depth such that the outer bottom edge of the footing is at least seven feet horizontally inside
the face of the slope.
6.6.17 Special subgrade presaturation is not deemed necessary prior to placing concrete; however,
the exposed foundation and slab subgrade soil should be moisture conditioned, as
necessary, to maintain a moist condition as would be expected in any such concrete
placement.
6.6.18 Where buildings or other improvements are planned near the top of a slope steeper than 3:1
(horizontal:vertical), special foundations and/or design considerations are recommended
due to the tendency for lateral soil movement to occur.
• For fill slopes less than 20 feet high, building footings should be deepened such
that the bottom outside edge of the footing is at least 7 feet horizontally from the
face of the slope.
• When located next to a descending 3:1 (horizontal:vertical) fill slope or steeper, the
foundations should be extended to a depth where the minimum horizontal distance
is equal to H/3 (where H equals the vertical distance from the top of the fill slope
to the base of the fill soil) with a minimum of 7 feet but need not exceed 40 feet.
The horizontal distance is measured from the outer, deepest edge of the footing to
the face of the slope. An acceptable altemative to deepening the footings would be
the use of a post-tensioned slab and foundation system or increased footing and
slab reinforcement. Specific design parameters or recommendations for either of
these altematives can be provided once the building location and fill slope
geometry have been determined.
• If swimming pools are planned, Geocon Incorporated should be contacted for a
review of specific site conditions.
• Swimming pools located within 7 feet of the top of cut or fill slopes are not
recommended. Where such a condition cannot be avoided, the portion of the
swimming pool wall within 7 feet of the slope face be designed assuming that the
adjacent soil provides no lateral support. This recommendation applies to fill
slopes up to 30 feet in height, and cut slopes regardless of height. For swimming
pools located near the top of fill slopes greater than 30 feet in height, additional
recommendations may be required and Geocon Incorporated should be contacted for
a review of specific site conditions.
Project No. 07193-32-03 - 15 - April 25, 2011
Revised July 14, 2011
• Although other improvements, which are relatively rigid or brittle, such as concrete
flatwork or masonry walls, may experience some distress if located near the top of
a slope, it is generally not economical to mitigate this potential. It may be possible,
however, to incorporate design measures that would permit some lateral soil
movement without causing extensive distress. Geocon Incorporated should be
consulted for specific recommendations.
6.6.19 The recommendations of this report are intended to reduce the potential for cracking of
slabs due to expansive soil (if present), differential settlement of existing soil or soil with
varying thicknesses. However, even with the incorporation of the recommendations
presented herein, foundations, stucco walls, and slabs-on-grade placed on such conditions
may still exhibit some cracking due to soil movement and/or shrinkage. The occurrence of
concrete shrinkage cracks is independent of the supporting soil characteristics. Their
occurrence may be reduced and/or controlled by limiting the slump of the concrete, proper
concrete placement and curing, and by the placement of crack control joints at periodic
intervals, in particular, where re-entrant slab comers occur.
6.6.20 Geocon Incorporated should be consulted to provide additional design parameters as
required by the stmctural engineer.
6.7 Retaining Walls and Lateral Loads
6.7.1 The stmctural engineer should determine the seismic design category for the project in
accordance with Section 1613 of the 2010 CBC. If the project possesses a seismic design
category of D, E, or F, the proposed retaining walls should be designed with seismic lateral
pressures. The seismic load exerted on the wall should be a triangular distribution with a
pressure of 17H (where H is the height of the wall, in feet, resulting in pounds per square
foot [psf]) exerted at the top of the wall and zero at the base of the wall. We used a peak
site acceleration of 0.31g calculated from Section 1803.5.12 of the 2010 Califomia
Building Code (SDS/2.5) and applying a pseudo-static coefficient of 0.33. Altematively, a
pseudo-static acceleration (kn) of 0.1 Og may also be used.
6.7.2 Retaining walls not restrained at the top and having a level backfill surface should be
designed for an active soil pressure equivalent to the pressure exerted by a fluid with a
density of 35 pounds per cubic foot (pcf). Where the backfill will be inclined at no steeper
than 2.0 to 1.0, an active soil pressure of 55 pcf is recommended. These soil pressures
assume that the backfill materials within an area bounded by the wall and a 1:1 plane
extending upward from the base of the wall possess an Expansion Index of less than 50.
Project No. 07193-32-03 - 16- April 25, 2011
Revised July 14, 2011
6.7.3 Unrestrained walls are those that are allowed to rotate more than O.OOIH (where H equals
the height of the retaining wall portion of the wall in feet) at the top of the wall. Where
walls are restrained from movement at the top, an additional uniform pressure of 7H psf
should be added to the above active soil pressure.
6.7.4 Retaining walls should be provided with a drainage system (Figure 6) adequate to prevent
the buildup of hydrostatic forces and should be waterproofed as required by the project
architect. The use of drainage openings through the base of the wall (weep holes) is not
recommended where the seepage could be a nuisance or otherwise adversely affect the
property adjacent to the base of the wall. The above recommendations assume a properly
compacted granular (EI less than 50) free-draining backfill material with no hydrostatic
forces or imposed surcharge load. If conditions different than those described are
anticipated, or if specific drainage details are desired, Geocon Incorporated should be
contacted for additional recommendations.
6.7.5 In general, wall foundations at least 12-inches wide and 12-inches deep may be designed
for an allowable soil bearing pressure of 2,000 psf, provided the soil within 3 feet below
the base of the wall has an Expansion Index of less than 90.
6.7.6 Footings that must be placed within seven feet of the top of slopes should be extended in
depth such that the outer bottom edge of the footing is at least seven feet horizontally inside
the face of the slope.
6.7.7 For resistance to lateral loads, an allowable passive earth pressure equivalent to a fluid with
a density of 300 pcf is recommended for footings or shear keys poured neat against
properly compacted granular fill soils or undisturbed natural soils. The allowable passive
pressure assumes a horizontal surface extending away from the face of the wall at least
5 feet or three times the height of surface generating the passive pressure, whichever is
greater. For 2:1 (H:V) sloping conditions in front of the surface generating the passive
pressure, an allowable passive earth pressure of 200 pcf is recommended. The upper
12 inches of material not protected by floor slabs or pavement should not be included in the
design for lateral resistance. A friction coefficient of 0.40 may be used for resistance to
sliding between soil and concrete. This friction coefficient may be combined with the
allowable passive earth pressure when determining resistance to lateral loads.
6.7.8 The recommendations presented above are generally applicable to the design of rigid
concrete or masonry retaining walls having a maximum height of 8 feet. In the event that
Project No. 07193-32-03 - 17 - April 25, 2011
Revised July 14, 2011
walls higher than 8 feet or other types of walls are planned, such as crib-type walls, Geocon
Incorporated should be consulted for additional recommendations.
6.8 Geogrid-Reinforced Retaining Walls
6.8.1 We understand that Geogrid Reinforced Earth Walls may be used for the project. These
walls consist of a reinforced earth zone connected to modular block facing units. Typically,
geogrid reinforcement is placed at specified levels of the wall, connected to the facing
block units and extended behind the wall a specified distance. The type and strength of
geogrid as well as the embedment depth and vertical spacing are determined based on the
shear strength characteristics of the soils being reinforced and retained.
6.8.2 We recommend the following geotechnical parameters for design of the geosynthetic
reinforced walls. Sufficient samples should of stockpile soils to be used as wall backfill
should be obtained and tested to evaluate the suitability of the soil for use as wall backfill.
TABLE 6.8
GEOTECHNICAL PARAMETERS FOR GEOGRID REINFORCED WALLS
Parameter Reinforced Zone Retained Zone Foundation Zone
Angle of Internal Friction 30 degrees 30 degrees 30 degrees
Cohesion Opsf 100 psf 100 psf
Wet Unit Weight 130 pcf 130 pcf 130 pcf
6.8.3 An allowable soil bearing pressure of 2,000 psf should be used for foundation design and
calculations for wall bearing. This bearing pressure assumes a minimum foundation width
and depth of 12 inches. The allowable soil bearing pressure may be increased by 300 psf
and 500 psf for each additional foot of foundation width and depth, respectively, up to a
maximum allowable soil bearing pressure of 4,000 psf.
6.8.4 The above soil parameters are based on direct shear strength tests performed during
previous geotechnical investigations and represent some of the on-site materials. Geocon
has no way of knowing whether these materials will actually be used for the wall during
constmction. It is up to the wall designer to use his judgment in selection of design
parameters. As such, once backfill materials have been selected and/or stockpiled,
sufficient shear tests should be conducted on samples of the proposed backfill materials to
verify they conform to actual design values. Results should be provided to the designer to
Project No. 07193-32-03 18-April 25, 2011
Revised July 14, 2011
re-evaluate stability of the walls. Dependent upon test results, the designer may require
modifications to the original wall design (i.e., longer geogrid embedment lengths).
6.8.5 The wall should be provided with drainage system sufficient enough to prevent excessive
seepage through the wall and water at the base of the wall to prevent hydrostatic pressures
behind the wall.
6.8.6 Backfill materials within the reinforced zone should be compacted to at least 90 percent
relative compaction. This is applicable to the entire embedment width of the geogrid
reinforcement. Typically, wall designers specify no heavy compaction equipment within
3 feet of the face of the wall. However, smaller equipment (i.e. walk behind self-driven
compactors, or hand whackers) can be used to compact the materials without causing
deformation of the wall. If the designer specifies no compactive effort for this zone, then
the materials are essentially not properly compacted and the geogrid should not be relied
upon for reinforcement, and overall embedment lengths will have to be increased to
account for the difference.
6.8.7 Geogrid reinforcement must elongate to develop full tensile resistance. This elongation
generally results in movement at the top of the wall. The amount of movement is dependent
upon the height of the wall (i.e., higher walls rotate more) and the type of geogrid
reinforcing used. In addition, over time geogrid has been known to exhibit creep
(sometimes as much as 5 percent) and can undergo additional movement. Given this
condition, the owner should be aware that stmctures and pavement placed within the
reinforced and retained zones of the wall might undergo movement. It is recommended that
buildings be setback a horizontal distance from the wall equivalent to the height of the
wall. Pavement and concrete flatwork at the top edge of the wall may exhibit cracking in
the event of wall movement. This is particularly possible in the swimming pool and Jacuzzi
areas where improvements are planned within the wall zone. Additional pavement or
concrete flatwork recommendations can be provided upon request, including geosynthetic
reinforcement of asphalt concrete or aggregate base, increased concrete thickness,
increased reinforcement, and closer joint spacing.
6.9 Preliminary Pavement Recommendations
6.9.1 Preliminary pavement recommendations for the parking lots and driveways are provided
below. The final pavement sections should be based on the R-Value of the subgrade soil
encountered at final subgrade elevation. Based on the laboratory R-value testing we have
assumed an R-Value of 16 for the subgrade soil for the purposes of this preliminary
analysis. The project civil engineer and developer should review the pavement designation
Project No. 07193-32-03 - 19- April 25, 2011
Revised July 14, 2011
to determine appropriate traffic index for pavement thickness. Preliminary flexible
pavement sections are presented in Table 6.9.1. R-Value samples should be obtained
subsequent to final grading to determine the final pavement design.
TABLE 6.9.1
PRELIMINARY FLEXIBLE PAVEMENT SECTION
Traffic Index Assumed
Subgrade R-Value
Asphalt Concrete
(inches)
Class 2
Aggregate Base
(inches)
4.5 16 4* 4
5.0 16 4* 6
6.0 16 4* 10
7.0 16 4* 13
7.5 16 5 13
*City of Carlsbad minimum
6.9.2 Class 2 aggregate base should conform to Section 26-1.02A of the Standard Specifications
for the State of Califomia Department of Transportation (Caltrans) and should be
compacted to a dry density of at least 95 percent of the maximum dry density at near
optimum moisture content as determined by ASTM D 1557-07. The asphalt concrete
should conform to Section 203-6 of the Standard Specifications for Public Works
Construction (Green Book).
6.9.3 Pavement subgrade soils should be scarified, moisture conditioned as necessary, and
recompacted to a dry density of at least 95 percent of the laboratory maximum dry density
near to slightly above optimum moisture content as determined by ASTM D1557-07. The
depth of processing should be at least 12 inches. Base material should be moisture
conditioned near to slightly above optimum moisture content and compacted to a dry
density of at least 95 percent of the laboratory dry density. Asphalt concrete should be
compacted to at least 95 percent of the laboratory Hveem density as determined by
ASTM D 2726-05A.
6.9.4 The base thickness can be reduced if a reinforcement geogrid within the base section is
used during the installation of the pavement. Geocon should be contact for additional
recommendations, if required.
6.9.5 Prior to placing base materials, the subgrade soil should be scarified, moisture conditioned
as necessary, and recompacted to a dry density of at least 95 percent of the laboratory
Project No. 07193-32-03 •20-April 25,2011
Revised July 14, 2011
maximum dry density near to slightly above optimum moisture content as determined by
ASTM D 1557-07. The depth of compaction should be at least 12 inches. Similarly, the base
material should be compacted to a dry density of at least 95 percent of the laboratory
maximum dry density near to slightly above optimum moisture content as determined by
ASTM D 1557-07.
6.9.6 A rigid Portland Cement concrete (PCC) pavement section should be placed in driveway
entrance aprons, and trash bin loading/storage areas. The concrete pad for trash tmck areas
should be large enough such that the tmck wheels will be positioned on the concrete during
loading. We calculated the rigid pavement section in general conformance with the
procedure recommended by the American Concrete Institute report ACI 330R-08 Guide for
Design and Constmction of Concrete Parking Lots using the parameters presented in
Table 6.9.2.
TABLE 6.9.2
RIGID PAVEMENT DESIGN PARAMETERS
Design Parameter Design Value
Modulus of subgrade reaction, k 100 pei
Modulus of rupture for concrete, MR 500 psi
Traffic Category, TC AandC
Average daily truck traffic, ADTT 10 and 100
6.9.7 Based on the criteria presented herein, the PCC pavement sections should have a minimum
thickness as presented in Table 6.9.3.
TABLE 6.9.3
RIGID PAVEMENT RECOMMENDATIONS
Location Portland Cement Concrete (inches)
Automobile Parking Areas (TC=A) 5.5
Heavy Truck and Fire Lane Areas (TC=C) 7.0
6.9.8 The PCC pavement should be placed over subgrade soil that is compacted to a dry density
of at least 95 percent of the laboratory maximum dry density near to slightly above
optimum moisture content. This pavement section is based on a minimum concrete
compressive strength of approximately 3,000 psi (pounds per square inch).
Project No. 07193-32-03 -21 April 25, 2011
Revised July 14, 2011
6.9.9 A thickened edge or integral curb should be constmcted on the outside of concrete slabs
subjected to wheel loads. The thickened edge should be 1.2 times the slab thickness or a
minimum thickness of 2 inches, whichever results in a thicker edge, and taper back to the
recommended slab thickness 4 feet behind the face of the slab (e.g., a 7-inch-thick slab
would have a 9-inch-thick edge). Reinforcing steel will not be necessary within the
concrete for geotechnical purposes with the possible exception of dowels at constmction
joints as discussed herein.
6.9.10 To control the location and spread of concrete shrinkage cracks, crack-control joints
(weakened plane joints) should be included in the design of the concrete pavement slab.
Crack-control joints should not exceed 30 times the slab thickness with a maximum spacing
of 12.5 feet and 15 feet for the 5.5 and 7-inch-thick slabs, respectively (e.g., a 7-inch-thick
slab would have a 15-foot spacing pattem), and should be sealed with an appropriate sealant
to prevent the migration of water through the control joint to the subgrade materials. The
depth of the crack-control joints should be determined by the referenced ACI report.
6.9.11 To provide load transfer between adjacent pavement slab sections, a butt-type constmction
joint should be constmcted. The butt-type joint should be thickened by at least 20 percent
at the edge and taper back at least 4 feet from the face of the slab. As an altemative to the
butt-type constmction joint, dowelling can be used between constmction joints for
pavements of 7 inches or thicker. As discussed in the referenced ACI guide, dowels should
consist of smooth, 1-inch-diameter reinforcing steel 14 inches long embedded a minimum
of 6 inches into the slab on either side of the constmction joint. Dowels should be located
at the midpoint of the slab, spaced at 12 inches on center and lubricated to allow joint
movement while still transferring loads. In addition, tie bars should be installed as
recommended in Section 3.8.3 ofthe referenced ACI guide. The stmctural engineer should
provide other altemative recommendations for load transfer.
6.9.12 The performance of pavement is highly dependent on providing positive surface drainage
away from the edge of the pavement. Ponding of water on or adjacent to the pavement will
likely result in pavement distress and subgrade failure. Drainage from landscaped areas
should be directed to controlled drainage stmctures. Landscape areas adjacent to the edge
of asphalt pavements are not recommended due to the potential for surface or irrigation
water to infiltrate the underlying permeable aggregate base and cause distress. Where such
a condition cannot be avoided, consideration should be given to incorporating measures
that will significantly reduce the potential for subsurface water migration into the aggregate
base. If planter islands are planned, the perimeter curb should extend at least 6 inches
below the level of the base materials.
Project No. 07193-32-03 - 22 - April 25, 2011
Revised July 14, 2011
6.10 Stormwater Management
6.10.1 If low-impact development (LID) integrated management practices (IMP's) are being
considered, Geocon should review the design and provide specific geotechnical
recommendations to reduce the potential adverse impacts to both on and off-site properties.
6.10.2 If not property constmcted, there is a potential for distress to improvements and properties
located hydrologically down gradient or adjacent to these devices. Factors such as the
amount of water to be detained, its residence time, and soil permeability have an important
affect on seepage transmission and the potential adverse impacts that may occur if the
storm water management features are not properly designed and constmcted. Based on the
results of our recent testing using a Guelph permeameter, the infiltration rate of the native
formational materials is approximately 0.002 in/hr, therefore infiltration IMP's are
considered infeasible. We have not performed a hydrogeology study at the site. Down-
gradient and adjacent properties may be subjected to seeps, springs, slope instability, raised
groundwater, movement of foundations and slabs, or other impacts as a result of water
infiltration.
6.10.3 Due to site soil and geologic conditions, a heavy duty, non-permeable liner should be
placed beneath any hydro-modification areas where water infiltration into the underlying
soils is planned. However, the existing detention basins located down-gradient from the
development may be considered for hydromodification. The strength and thickness of the
membrane, and constmction method should be adequate to assure that the liner will not be
compromised throughout the life of the system. In addition, civil engineering provisions
should be implemented to assure that the capacity of the system is never exceeded resulting
in over topping or malfunctioning of the device. The system should also include a long-
term maintenance program or periodic cleaning to prevent clogging of the filter media or
drain envelope. Geocon Incorporated has no opinion regarding the design of the filtration
system or its effectiveness.
6.11 Site Drainage and Moisture Protection
6.11.1 Adequate site drainage is critical to reduce the potential for differential soil movement,
erosion and subsurface seepage. Under no circumstances should water be allowed to pond
adjacent to footings. The site should be graded and maintained such that surface drainage is
directed away from stmctures in accordance with 2010 CBC 1804.3 or other applicable
standards. In addition, surface drainage should be directed away from the top of slopes into
swales or other controlled drainage devices. Roof and pavement drainage should be
directed into conduits that carry mnoff away from the proposed stmcture.
Project No. 07193-32-03 - 23 - April 25, 2011
Revised July 14, 2011
6.11.2 Underground utilities should be leak free. Utility and irrigation lines should be checked
periodically for leaks, and detected leaks should be repaired promptly. Detrimental soil
movement could occur if water is allowed to infiltrate the soil for prolonged periods
of time.
6.12 Grading and Foundation Plan Review
6.12.1 Geocon Incorporated should review the grading plans and foundation plans for the project
prior to final design submittal to evaluate whether additional analyses and/or
recommendations are required.
Project No. 07193-32-03 - 24 - April 25, 2011
Revised July 14,2011
LIMITATIONS AND UNIFORMITY OF CONDITIONS
1. The firm that performed the geotechnical investigation for the project should be retained to
provide testing and observation services during constmction to provide continuity of
geotechnical interpretation and to check that the recommendations presented for geotechnical
aspects of site development are incorporated during site grading, constmction of
improvements, and excavation of foundations. If another geotechnical firm is selected to
perform the testing and observation services during constmction operations, that firm should
prepare a letter indicating their intent to assume the responsibilities of project geotechnical
engineer of record. A copy of the letter should be provided to the regulatory agency for their
records. In addition, that firm should provide revised recommendations conceming the
geotechnical aspects of the proposed development, or a written acknowledgement of their
concurrence with the recommendations presented in our report. They should also perform
additional analyses deemed necessary to assume the role of Geotechnical Engineer of Record.
2. The recommendations of this report pertain only to the site investigated and are based upon
the assumption that the soil conditions do not deviate from those disclosed in the
investigation. If any variations or undesirable conditions are encountered during constmction,
or if the proposed construction will differ from that anticipated herein, Geocon Incorporated
should be notified so that supplemental recommendations can be given. The evaluation or
identification of the potential presence of hazardous or corrosive materials was not part of the
scope of services provided by Geocon Incorporated.
3. This report is issued with the understanding that it is the responsibility of the owner or his
representative to ensure that the information and recommendations contained herein are
brought to the attention of the architect and engineer for the project and incorporated into the
plans, and the necessary steps are taken to see that the contractor and subcontractors carry out
such recommendations in the field.
4. 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 be 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.
Project No. 07193-32-03 April 25, 2011
Revised July 14, 2011
THE GEOGRAPHICAL INFORMATION MADE AVAILABLE FOR DISPLAY WAS PROVIDED BY GOOGLE EARTH,
SUBJECT TO A LICENSING AGREEMENT. THE INFORMATION IS FOR ILLUSTRATIVE PURPOSES ONLY; IT IS
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SHALL INDEMNIFY, DEFEND AND HOLD HARMLESS GEOCON FROM ANY LABILITY INCURRED AS A RESULT
OF SUCH USE OR RELIANCE BY CLIENT.
GEOCON
INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
TMIRA DSK/GTYPD
VICINITY MAP
LA COSTA VILLAGE TOWNHOMES
CARLSBAD 3, CT 04-08
DOVE LANE AND EL CAMINO REAL
CARLSBAD, CALIFORNIA
DATE 07-14-2011 PROJECT NO. 07193 - 32 - 03 FIG. 1
Vicinity Map Y:\PROJECTS\07193-32-03 MOONSTONE\DETAILS\GVicinity Map.dwg
ASSUMED CONDITIONS
SLOPE HEIGHT H = 20 feet
SLOPE INCLINATION 2 : 1 (Horizontal : Vertical)
TOTAL UNIT WEIGHT OF SOIL = 125 pounds per cubic foot
ANGLE OF INTERNAL FRICTION <}) = 30 degrees
APPARENT COHESION C = 350 pounds per square foot
NO SEEPAGE FORCES
ANALYSIS :
7c<t. = 7H tan<t)
C
EQUATION (3-3), REFERENCE 1
FS = NcfC 7H EQUATION (3-2), REFERENCE 1
yc^ = 4.1 CALCULATED USING EQ. (3-3)
Ncf = 18 DETERMINED USING FIGURE 10, REFERENCE 2
FS = 2.5 FACTOR OF SAFETY CALCULATED USING EQ. (3-2)
REFERENCES:
1 Janbu, N., Stability Analysis of Slopes with Dimensionless Parameters, Harvard Soil Mechanics,
Series No. 46,1954
2 Janbu, N., Discussion of J.M. Bell, Dimensionless Parameters for Homogeneous Earth Slopes,
Joumal of Soil Mechanics and Foundation Design, No. SM6, November 1967.
SLOPE STABILITY ANALYSIS
GEOCON ^)
INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
LA COSTA VILLAGE TOWNHOMES
CARLSBAD 3, CT 04-08
DOVE LANE AND EL CAMINO REAL
CARLSBAD, CALIFORNIA
TM/RA 1 1 DSK/GTYPD DATE 07-14-2011 | PROJECT NO. 07193 - 32 - 03 | FIG. 3
Y;\PROJECrS\07193-32-03 MOONSTONE\DErAILS\SSAF.dwg
ASSUMED CONDITIONS :
SLOPE HEIGHT H = Infinite
DEPTH OF SATURATION Z = 3 feet
SLOPE INCLINATION 2 : 1 (Horizontal : Vertical)
SLOPE ANGLE i = 26.6 degrees
UNIT WEIGHT OF WATER = 62.4 pounds per cubic foot
TOTAL UNIT WEIGHT OF SOIL It = 125 pounds per cubic foot
ANGLE OF INTERNAL FRICTION = 30 degrees
APPARENT COHESION C = 350 pounds per square foot
SLOPE SATURATED TO VERTICAL DEPTH Z BELOW SLOPE FACE
SEEPAGE FORCES PAFIALLEL TO SLOPE FACE
ANALYSIS :
FS =
7^ Z sin i COS i
= 2.9
REFERENCES:
1 Haefeli, R. The Stability of Slopes Acted Upon by Parallel Seepage, Proc.
Second International Conference, SMFE, Rotterdam, 1948,1, 57-62
2 Skempton, A. W., and F.A. Delory, Stability of Natural Slopes in London Clay, Proc.
Fourth International Conference, SMFE, London, 1957,2, 378-81
SURFICIAt SOPE STABILITY ANALYSIS
GEOCON
INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
TM/RA DSK/GTYPD
LA COSTA VILLAGE TOWNHOMES
CARLSBAD 3, CT 04-08
DOVE LANE AND EL CAMINO REAL
CARLSBAD, CALIFORNIA
DATE 07-14-2011 PROJECT NO. 07193 - 32 - 03 FIG. 4
Y:\PROJECTS\07193-32-03 MOONSTONE\DETAILS\SSSA.dwg
WALL FOOTING
SAND PAD GRADE
VAPOR
RETARDER
COLUMN FOOTING
CONCRETE SLAB fa.
SAND
jfil
..SEE REPORT FOR FOUNDATION WITDH AND DEPTH RECOMMENDATION NO SCALE
WALL/COLUMN FOOTING DIMENSION DETAIL
GEOCON ^)
INCORPORATED ^Ip^
GEOTECHNICAL CONSULTANTS
6960 FL\NDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
LA COSTA VILLAGE TOWNHOMES
CARLSBAD 3, CT 04-08
DOVE LANE AND EL CAMINO REAL
CARLSBAD, CALIFORNIA
TM/RA 1 1 DSK/GTYPD DATE 07-14-2011 j PROJECT NO. 07193 - 32 - 03 | FIG. 5
COLfOOT3/DWG. Y:\PROJECTS\07193-32-03 M0ONST0NE\DETAILS\COLF00T3.dwg
GROUND SURFACE
PROPOSED
RETAINING WALL
TEMPORARY BACKCUT
PER OSHA
GROUND SURFACE •
wm
MIRAFI 140N FILTER FABRIC
(OR EQUIVALENT)
OPEN GRADED
1" MAX. AGGREGATE
4- DIA. PERFORATED SCHEDULE
40 PVC PIPE EXTENDED TO
APPROVED OUTLET
WATER PROOFING
PER ARCHITECT
GROUND SURFACE
DRAINAGE PANEL (MIRADRAIN 6000
OR EQUIVALENT)
3/4" CRUSHED ROCK
(1 CU.FT./FT.)
-..^ FILTER FABRIC ENVELOPE
w*' "r-^'^MIRAFI 140N OR EQUIVALENT
4" DIA. SCHEDULE 40 PERFORATED
PVC PIPE OR APPROVED TOTAL DRAIN
EXTENDED TO APPROVED OUTLET
NOTE:
DRAIN SHOULD BE UNIFORMLY SLOPED TO GRAVITY OUTLET
OR TO A SUMP WHERE WATER CAN BE REMOVED BY PUMPING
NO SCALE
TYPICAL RETAINING WALL DRAIN DETAIL
GEOCON
INCORPORATED
GEOTECHNICAL CONSULTANTS
6960 FL\NDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
TM/RA DSK/GTYPD
LA COSTA VILLAGE TOWNHOMES
CARLSBAD 3, CT 04-08
DOVE LANE AND EL CAMINO REAL
CARLSBAD, CALIFORNIA
DATE 07-14-2011 PROJECT NO. 07193 - 32 - 03 FIG. 6
Y:\PROJEaS\07193-32-03 MOONSTONE\DETAILS\REr WALL DRAIN DETAILS_2.dwg
APPENDIX M A
APPENDIX A
FIELD INVESTIGATION
Included herewith is a description of our previous field investigation (Geotechnical Investigation,
Dove Lane Senior Apartments, Carlsbad, Califomia, Geocon Incorporated, dated January 5, 2000)
and copies of the trench logs of exploratory excavations.
The previous field investigation was performed on December 13, 1999, and consisted of excavating
ten backhoe trenches at the approximate locations shown on Figure 2. The trenches were excavated to
depths ranging from 4'/2 feet to 11 feet below existing grade using a John Deere 310 backhoe.
Disturbed bulk samples were obtained from the excavations.
Soil conditions encountered in the trenches were visually examined, classified and logged in general
conformance with the ASTM Practice for Description and Identification of Soils (Visual-Manual
Procedure D2844). Logs of the exploratory trenches are presented on Figures A-1 through A-10. The
logs depict the various soil types encountered and indicate the depths at which samples were
obtained.
Project No. 07193-32-03 April 25, 2011
Revised July 14, 2011
PROJECT NO. 06432-2201
DEPTH
IN
FEET
SAMPLE
NO.
> CD O
H
SOIL
CLASS
(USCS)
TRENCH T 1
ELEV. (MSL.)
EQUIPMENT
DATE COMPLETED 12/13/99
JD 555 TRACKED HOE UJ
UJ
a
UJ
MATERIAL DESCRIPTION
- 2 Tl-1
Tl-2
Tl-3
6 -
- 8
10
Tl-4
Tl-5
m m
m m m
m
ML TOPSOIL
Soft, dry to damp, light brown, Sandy SILT,
coinmon roots, abundant pores
SANTIAGO FORMATION
Very dense, damp, grayish-brown and strong
brown mottled, Silty SANDSTONE; common roots,
strong columnar soil structure (moderately
weathered)
Grades to moderately weathered, no soil stmcture,
light gray and brownish-yellow mottled, Silty, fine
to medium SANDSTONE, moist, moderately hard,
massive, with no evident stratification or jointing
-Increasing hardness and mottling, very moist
106.3 9.0
TRENCH TERMINATED AT 10 FEET
Figure A-1, Log of Trench T 1 OLSA
SAMPLE SYMBOLS u.. . SAMPLING UNSUCCESSFUL c. . STANDARD PENETRATION TEST • .. . DRIVE SAMPLE (UNDISTURBED)
m.. . DISTURBED OR BAG SAMPLE . CHUNK SAMPLE ¥ •• . WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION ANO AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. 06432-2201
DEPTH
IN
FEET
SAMPLE
NO.
> a o
_j o
I-
H
SOIL
CLASS
(USCS)
TRENCH T 2
ELEV. (MSL.)
EQUIPMENT
DATE COMPLETED 12/13/99
JD 555 TRACKED HOE coy UJs;
CQ
a: a u
MATERIAL DESCRIPTION
2 -
T2-1
6 -
ML TOPSOIL
Soft, dry to damp, light brown, Sandy SILT,
common roots, abundant pores
SANTIAGO FORMATION
Dense to very dense, damp, grayish-brown and
strong brown mottled, Silty SANDSTONE; common
roots, strong columnar soil structure, (very
weathered)
-Grades to moderately weathe^^ no soil structure
Moderately hard, moist, very pale brown to
yellowish-brown, Silty, fme to medium
SANDSTONE; vague stratification without parting,
approximately horizontal, scattered, steep, wavy
tight joints
TRENCH TERMINATED AT 7 FEET
Figure A-2, Log of Trench T 2 DLSA
SAMPLE SYMBOLS ° ""' UNSUCCESSFUL
^ ... DISTURBED OR BAG SAMPLE
c.
B..
. STANDARD PENETRATION TEST DRIVE SAMPLE (UNDISTURBED)
. CHUNK SAMPLE 3C ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. 06432-2201
DEPTH
IN
FEET
SAMPLE
NO.
> CD O
H
SOIL
CLASS
(USCS)
TRENCH T 3
ELEV. (MSL.)
EQUIPMENT
DATE COMPLETED 12/13/99
JD555 TRACKED HOE
Q.' .fJta
y^
UJ
MATERIAL DESCRIPTION
- 2
- 4
T3-1
ML TOPSOIL
Soft, dry to damp, light brown, Sandy SILT;
common roots, abimdant pores
SANTIAGO FORMATION
Very dense, damp, grayish-brown and strong
brown mottled, Silty SANDSTONE; common roots,
stroiig coluiniiar soil structure (very weathered) _
Grades to moderately weathered, moderately hard,
moist, light gray and brownish-yellow mottled,
Silty, fine to medium SANDSTONE; vague
stratification without parting, approximately
horizontal, scattered, steep, wavy tight joints
TRENCH TERMINATED AT 7 FEET
112.0 11.9
Figure A-3, Log of Trench T 3 OLSA
SAMPLE SYMBOLS ° """ '^"'"-'"'^ UNSUCCESSFUL
^ ... DISTURBED OR BAG SAMPLE
E..
B..
. STANDARD PENETRATION TEST DRIVE SAMPLE (UNDISTURBED)
. CHUNK SAMPLE I ... WATER TABLE OR SEEPAGE
inc LUU ur suosuKi-AUt CUNUJIIUNS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. 06432-2201
DEPTH
IN
FEET
SAMPLE
NO.
>-CD O _l O I
SOIL
CLASS
(USCS)
TRENCH T 4
ELEV. (MSL.)
EQUIPMENT
DATE COMPLETED 12/13/99
JD555 TRACKED HOE
1x1^
cnH
UJ3! a
y-\
u
- 0 MATERIAL DESCRIPTION
2 -
4 -
ML TOPSOIL
Soft, dry to damp, light brown, Sandy SILT;
common roots, abimdant pores
SANTL\GO FORMATION (TS)
Very dense, damp, grayish-brown and strong
brown mottled, Silty, fine to medium
SANDSTONE; common roots, strong columnar soil
strucjuje (very weathered)
Grades to moderately weathered, no soil stmcmre,
light gray and brownish-yellow molded, Silty, fine
to medium SANDSTONE, vague stratification with
poor parting
TRENCH TERMINATED AT 6 FEET
Figure A-4, Log of Trench T 4 DLSA
SAMPLE SYMBOLS ° '"" UNSUCCESSFUL
^ ... DISTURBED OR BAG SAMPLE
E
B
.. STANDARD PENETRATION TEST DRIVE SAMPLE (UNDISTURBED)
.. CHUNK SAMPLE I ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. 06432-2201
DEPTH
IN
FEET
SAMPLE
NO.
>• CD O _l O X
I-
H
SOIL
CLASS
(USCS)
TRENCH T 5
ELEV. (MSL.)
EQUIPMENT
DATE COMPLETED 12/13/99
JD555 TRACKED HOE
SUJ'
cnR
Ss
go
a
y-\
o
- 2 -
4 -
T5-1 p.
T5-2
ML
MATERIAL DESCRIPTION
TOPSOIL
Soft, dry to damp, light brown, Sandy SILT;
conmion roots, abundant pores
SANITAGO FORMATION (TS)
Very dense, damp, grayish-brown and strong
brown motded, Silty SANDSTONE; common roots,
strong coluinnar soil structure (very weathered)
Grades to moderately weathered, very pale brown
and yellow, Silty SANDSTONE, pale brown, hard,
Sandy SILTSTONE, and pale yellow SANDSTONE;
stratification with poor parting, approximately
horizontal
y
109.6
TRENCH TERMINATED AT 6 FEET
13.6
Figure A-5, Log of Trench T 5 DLSA
SAMPLE SYMBOLS ^ - UNSUCCESSFUL
^ ... DISTURBED OR BAG SAMPLE
E..
B..
. STANDARD PENETRATION TEST DRIVE SAMPLE (UNDISTURBED)
. CHUNK SAMPLE ? . • • WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
OATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. 06432-2201
DEPTH
IN
FEET
SAMPLE
NO.
> CD O
H
SOIL
CLASS
(USCS)
TRENCH T 6
ELEV. (MSL.)
EQUIPMENT
DATE COMPLETED 12/13/99
JD 555 TRACKED HOE
SUJ'^
Hyi-
UJ
cn
iu^
a: a Ez
o
- 0
T6-1
- 6
MATERIAL DESCRIPTION
ML TOPSOIL
Soft, dry to damp, light brown, Sandy SILT,
common roots, abundant pores
SANTLVGO FORMATION
Very dense, damp, grayish-brown and strong
strong brown mottled, Silty SANDSTONE; common
roots, strong columnar soil strucmre (very
weathered)
Grades to moderately weathered, no soil structure,
moderately hard, very pale brown with yellow
mottling, Silty, fine to medium SANDSTONE; no
evident stratification
TRENCH TERMINATED AT 6 FEET
Figure A-6, Log of Trench T 6 OLSA
SAMPLE SYMBOLS ° """ ''^"'''"'^ UNSUCCESSFUL
^ ... DISTURBED OR BAG SAMPLE
E..
B..
. STANDARD PENETRATION TEST DRIVE SAMPLE (UNDISTURBED)
. CHUNK SAMPLE X ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. 06432-2201
DEPTH
IN
FEET
SAMPLE
NO.
5-CD O _l O X
SOIL
CLASS
(USCS)
TRENCH T 7
ELEV. (MSL.)
EQUIPMENT
DATE COMPLETED 12/13/99
JD 555 TRACKED HOE
H
;IU'
O.
z[S-l ft: a
UI
- 0
- 2
- 4
MATERIAL DESCRIPTION
T7-1
T7-2
ML TOPSOIL
Soft, dry to damp, light brown, Sandy SILT,
common roots, abundant pores
SANITAGO FORMATION
Very dense, damp, grayish-brown and strong
brown mottled, Silty SANDSTONE; common roots,
strong coluinnar soi] structure (very weathered)
Grades to moderately weathered, no soil structure,
moderately hard, moist, light gray and
brownish-yellow mottied, Silty, fine to medium
SANDSTONE; no evident stratification
TRENCH TERMINATED AT 6 FEET
109.0 7.2
Figure A-7, Log of Trench T 7 DLSA
SAMPLE SYMBOLS • ... SAMPLING UNSUCCESSFUL E ... STANDARD PENETRATION TEST
DISTURBED OR BAG SAMPLE B CHUNK SAMPLE
DRIVE SAMPLE (UNDISTURBED)
WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. 06432-2201
DEPTH
IN
FEET
SAMPLE
NO.
>-CD O _J O X H-H
SOIL
CLASS
(USCS)
TRENCH T 8
ELEV. (MSL.)
EQUIPMENT
DATE COMPLETED 12/13/99
JD 555 TRACKED HOE
Hyi-
UJ HS
Q.
gL
ft!
Q
UJ
Oe:
t-(Ji UJ
•o o
- 0 MATERIAL DESCRIPTION
T8-1
1*
ML TOPSOEL
Soft, dry to damp, light brown, Sandy SILT;
common roots, abundant pores
SANTTAGO FORMATION (TS)
Very dense, damp, grayish-brown and strong
brown mottled, Silty SANDSTONE; common roots,
stroiig colunmar soil structure
Grades to moderately weathered, no soil structure,
moderately hard, moist, pale brown and yellow
mottled, Silty, fine to coarse SANDSTONE; poor
parting on stratification, N60W, 15 degrees SW
TRENCH TERMINATED AT 5 FEET
Figure A-8, Log of Trench T 8 DLSA
SAMPLE SYMBOLS ° """ '^""''''^ UNSUCCESSFUL
^ ... DISTURBED OR BAG SAMPLE
E..
B..
. STANDARD PENETRATION TEST DRIVE SAMPLE (UNDISTURBED)
. CHUNK SAMPLE ? ••• WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INOICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. 06432-2201
DEPTH
IN
FEET
SAMPLE
NO.
CD O
H
SOIL
CLASS
(USCS)
TRENCH T 9
ELEV. (MSL.)
EQUIPMENT
DATE COMPLETED 12/13/99
JD555 TRACKED HOE
sy .
i-5u.
UJ
i(n^ 111 DC
Q
uit5 a:
Pi-
co
Ez
o
MATERIAL DESCRIPTION
2 -
4 -
T9-1
ML TOPSOIL
Soft, dry to damp, light brown, Sandy SILT;
common roots, abundant pores
SANTIAGO FORMATION (TS)
Very dense, damp, grayish-brown and strong
brown mottled, Silty SANDSTONE; common roots,
strong columnar soil strucmre
-Grades to moderately weathered, no soil structure,
moderately hard, moist, light gray and
brownish-yellow motded, Silty, fine to medium
SANDSTONE; poor parting on stratification,
N75E, 7 degrees SE
TRENCH TERMINATED AT 4.5 FEET
NEAR REFUSAL
Figure A-9, Log of Trench T 9 DLSA
SAMPLE SYMBOLS ° """ '^"'''''"^ UNSUCCESSFUL
^ ... DISTURBED OR BAG SAMPLE
E..
B..
. STANDARD PENETRATION TEST DRIVE SAMPLE (UNDISTURBED)
. CHUNK SAMPLE Y ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
OATE INOICATEO. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. 06432-2201
DEPTH
IN
FEET
SAMPLE
NO.
> CD O _l O X
I-
H
SOIL
CLASS
(USCS)
TRENCH T 10
ELEV. (MSL.)
EQUIPMENT
DATE COMPLETED 12/13/99
JD 555 TRACKED HOE
H
iUJ' O.
UJ cn«
iUJ; uj^m
H' gL
UJ
a
a
o
ui^5 ft:
UJ
•o o
MATERIAL DESCRIPTION
2 -
TlO-1
6 -
10
ML
SM
TOPSOIL
Soft, dry to damp, light brown, Sandy SILT;
common roots, abundant pores
ALLUVIUM
Loose, moist, medium brown, Silty, fine to
medium SAND
SANTTAGO FORMATION (TS)
Dense, moist, grayish-brown and strong brown
mottled, Silty SANDSTONE; common roots, strong
columnar soil structure
-Grades to moderately weathered, no soil strucmre
-Friable, moist to wet, light gray and
brownish-yellow mottled, Silty, fine to medium
SANDSTONE; vague stratification approximately
horizontal, large roots to 5 feet
-Seepage at 6 feet
TRENCH TERMINATED AT 11 FEET
Figure A-10, Log of Trench T 10 DLSA
SAMPLE SYMBOLS • ... SAMPLING UNSUCCESSFUL E ... STANDARD PENETRATION TEST
^ ... DISTURBED OR BAG SAMPLE B ... CHUNK SAMPLE
DRIVE SAMPLE (UNDISTURBED)
I ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
OATE INDICATEO. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS ANO TIMES.
APPENDIX
APPENDIX B
LABORATORY TESTING
Included herewith are laboratory test results associated with our previous geotechnical investigation
(Geocon, January 5, 2000). Tests were conducted on samples obtained from exploratory trench
excavations.
Laboratory tests were performed in accordance with generally accepted test methods of the ASTM or
other suggested procedures. Selected soil samples were tested for their in-place dry density and
moisture content, maximum dry unit weight and optimum moisture content, expansion potential, and
shear strength characteristics. An R-value test was also performed on a sample of the near-surface
soils to aid in designing pavements.
The results of our laboratory tests are presented on Tables B-I through B-IV. The in-place dry density
and moisture content results are indicated on the exploratory trench logs.
TABLE B-I
SUMMARY OF REMOLDED DIRECT SHEAR TEST RESULTS
Sample
No.
Dry Density
(pcf)
Moisture Content
(%)
Unit Cohesion
(psf)
Angle of Shear
Resistance (degrees)
T2-1* 102.4 13.9 400 30
T8-1* 103.9 14.8 350 30
•Samples remolded to approximately 90 percent relative compaction at near optimum moisture content.
TABLE B-II
SUMMARY OF LABORATORY EXPANSION INDEX TEST RESULTS
Sample No.
Moisture Content Dry Density
(pcf) Expansion Index Sample No.
Before Test (%) After Test (%)
Dry Density
(pcf) Expansion Index
T5-1 12.2 28.7 100.8 71
T7-1 9.2 25.5 111.7 2
Project No. 07193-32-03 -B-1 April 25, 2011
Revised July 14, 2011
e e s
e s
e
TABLE B-lll
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY
AND OPTIMUM MOISTURE CONTENT TEST RESULTS
Sample
No. Description Maximum Dry
Density (pcf)
Optimum Moisture
Content (% dry wt)
T2-1 Yellow brown, Silty, fine to medium SAND 114.4 13.4
T8-1 Yellow brown, Silty, fine to coarse SAND 116.2 14.0
8
e
B-IV
SUMMARY OF LABORATORY RESISTANCE VALUE TEST RESULTS
CALIFORNIA TEST METHOD NO. 301
Sample No. Description R-Value
B9-1 Gray brown, Silty, fine to medium SAND 16
e
m e e c
Project No. 07193-32-03 -B-2-April 25, 2011
Revised July 14, 2011
APPENDIX C
APPENDIX C
RECOMMENDED GRADING SPECIFICATIONS
FOR
LA COSTA VILLAGE TOWNHOMES
(CARLSBAD 3), CT 04-08
DOVE LANE AND EL CAMINO REAL
CARLSBAD, CALIFORNIA
PROJECT NO. 07193-32-03
RECOMMENDED GRADING SPECIFICATIONS
1. GENERAL
1.1 These Recommended Grading Specifications shall be used in conjunction with the
Geotechnical Report for the project prepared by Geocon Incorporated. The
recommendations contained in the text of the Geotechnical Report are a part of the
earthwork and grading specifications and shall supersede the provisions contained
hereinafter in the case of conflict.
1.2 Prior to the commencement of grading, a geotechnical consultant (Consultant) shall be
employed for the purpose of observing earthwork procedures and testing the fills for
substantial conformance with the recommendations of the Geotechnical Report and these
specifications. The Consultant should provide adequate testing and observation services so
that they may assess whether, in their opinion, the work was performed in substantial
conformance with these specifications. It shall be the responsibility of the Contractor to
assist the Consuhant and keep them apprised of work schedules and changes so that
personnel may be scheduled accordingly.
1.3 It shall be the sole responsibility of the Contractor to provide adequate equipment and
methods to accomplish the work in accordance with applicable grading codes or agency
ordinances, these specifications and the approved grading plans. If, in the opinion of the
Consultant, unsatisfactory conditions such as questionable soil materials, poor moisture
condition, inadequate compaction, adverse weather, result in a quality of work not in
conformance with these specifications, the Consultant will be empowered to reject the
work and recommend to the Owner that grading be stopped until the unacceptable
conditions are corrected.
2. DEFINITIONS
2.1 Owner shall refer to the owner of the property or the entity on whose behalf the grading
work is being performed and who has contracted with the Contractor to have grading
performed.
2.2 Contractor shall refer to the Contractor performing the site grading work.
2.3 Civil Engineer or Engineer of Work shall refer to the California licensed Civil Engineer
or consuhing firm responsible for preparation of the grading plans, surveying and verifying
as-graded topography.
Gl rev. 04/2009
2.4 Consultant shall refer to the soil engineering and engineering geology consulting firm
retained to provide geotechnical services for the project.
2.5 Soil Engineer shall refer to a California licensed Civil Engineer retained by the Owner,
who is experienced in the practice of geotechnical engineering. The Soil Engineer shall be
responsible for having qualified representatives on-site to observe and test the Contractor's
work for conformance with these specifications.
2.6 Engineering Geologist shall refer to a California licensed Engineering Geologist retained
by the Owner to provide geologic observations and recommendations during the site
grading.
2.7 Geotechnical Report shall refer to a soil report (including all addenda) which may include
a geologic reconnaissance or geologic investigation that was prepared specifically for the
development of the project for which these Recommended Grading Specifications are
intended to apply.
3. MATERIALS
3.1 Materials for compacted fill shall consist of any soil excavated from the cut areas or
imported to the site that, in the opinion of the Consultant, is suitable for use in construction
of fills. In general, fill materials can be classified as soil fills, soil-rock fills or rock fills, as
defined below.
3.1.1 Soil fills are defined as fills containing no rocks or hard lumps greater than 12
inches in maximum dimension and containing at least 40 percent by weight of
material smaller than inch in size.
3.1.2 Soil-rock fills are defined as fills containing no rocks or hard lumps larger than 4
feet in maximum dimension and containing a sufficient matrix of soil fill to allow
for proper compaction of soil fill around the rock fragments or hard lumps as
specified in Paragraph 6.2. Oversize rock is defined as material greater than 12
inches.
3.1.3 Rock fills are defined as fills containing no rocks or hard lumps larger than 3 feet
in maximum dimension and containing little or no fines. Fines are defined as
material smaller than VA inch in maximum dimension. The quantity of fines shall be
less than approximately 20 percent of the rock fill quantity.
Gl rev. 04/2009
3.2 Material of a perishable, spongy, or otherwise unsuitable nature as determined by the
Consultant shall not be used in fills.
3.3 Materials used for fill, either imported or on-site, shall not contain hazardous materials as
defined by the California Code of Regulafions, Title 22, Division 4, Chapter 30, Articles 9
and 10; 40CFR; and any other applicable local, state or federal laws. The Consultant shall
not be responsible for the identification or analysis of the potential presence of hazardous
materials. However, if observations, odors or soil discoloration cause Consultant to suspect
the presence of hazardous materials, the Consultant may request from the Owner the
termination of grading operations within the affected area. Prior to resuming grading
operations, the Owner shall provide a written report to the Consultant indicating that the
suspected materials are not hazardous as defined by applicable laws and regulations.
3.4 The outer 15 feet of soil-rock fill slopes, measured horizontally, should be composed of
properly compacted soil fill materials approved by the Consuhant. Rock fill may extend to
the slope face, provided that the slope is not steeper than 2:1 (horizontal:vertical) and a soil
layer no thicker than 12 inches is track-walked onto the face for landscaping purposes. This
procedure may be utilized provided it is acceptable to the governing agency, Owner and
Consultant.
3.5 Samples of soil materials to be used for fill should be tested in the laboratory by the
Consultant to determine the maximum density, optimum moisture content, and, where
appropriate, shear strength, expansion, and gradation characteristics of the soil.
3.6 During grading, soil or groundwater conditions other than those identified in the
Geotechnical Report may be encountered by the Contractor. The Consultant shall be
notified immediately to evaluate the significance of the unanticipated condition
4. CLEARING AND PREPARING AREAS TO BE FILLED
4.1 Areas to be excavated and filled shall be cleared and grubbed. Clearing shall consist of
complete removal above the ground surface of trees, stumps, brush, vegetation, man-made
structures, and similar debris. Grubbing shall consist of removal of stumps, roots, buried
logs and other unsuitable material and shall be performed in areas to be graded. Roots and
other projections exceeding 1V2 inches in diameter shall be removed to a depth of 3 feet
below the surface of the ground. Borrow areas shall be grubbed to the extent necessary to
provide suitable fill materials.
Gl rev. 04/2009
4.2 Any asphah pavement material removed during clearing operations should be properly
disposed at an approved off-site facility. Concrete fragments that are free of reinforcing
steel may be placed in fills, provided they are placed in accordance with Section 6.2 or 6.3
of this document.
4.3 After clearing and grubbing of organic matter and other unsuitable material, loose or
porous soils shall be removed to the depth recommended in the Geotechnical Report. The
depth of removal and compaction should be observed and approved by a representative of
the Consultant. The exposed surface shall then be plowed or scarified to a minimum depth
of 6 inches and until the surface is free from uneven features that would tend to prevent
uniform compaction by the equipment to be used.
4.4 Where the slope ratio of the original ground is steeper than 5:1 (horizontahvertical), or
where recommended by the Consultant, the original ground should be benched in
accordance with the following illustration.
TYPICAL BENCHING DETAIL
Finish Grade Original Ground
Remove All
Unsuitable Material
As Recommended By
Consultant Slope To Be Such That
Sloughing Or Sliding
Does Not Occur
Finish Slope Surface
See Note 1 See Note 2.
No Scale
DETAIL NOTES: (1) Key width "B" should be a minimum of 10 feet, or sufficiently wide to permit
complete coverage with the compaction equipment used. The base of the key should
be graded horizontal, or inclined slightly into the natural slope.
(2) The outside of the key should be below the topsoil or unsuitable surficial material
and at least 2 feet into dense formational material. Where hard rock is exposed in the
bottom of the key, the depth and configuration of the key may be modified as
approved by the Consultant.
Gl rev. 04/2009
4.5 After areas to receive fill have been cleared and scarified, the surface should be moisture
conditioned to achieve the proper moisture content, and compacted as recommended in
Section 6 of these specifications.
5. COMPACTION EQUIPMENT
5.1 Compaction of soil or soil-rock fill shall be accomplished by sheepsfoot or segmented-steel
wheeled rollers, vibratory rollers, multiple-wheel pneumatic-tired rollers, or other types of
acceptable compaction equipment. Equipment shall be of such a design that it will be
capable of compacting the soil or soil-rock fill to the specified relative compaction at the
specified moisture content.
5.2 Compaction of rock fills shall be performed in accordance with Section 6.3.
6. PLACING, SPREADING AND COMPACTION OF FILL MATERIAL
6.1 Soil fill, as defined in Paragraph 3.1.1, shall be placed by the Contractor in accordance with
the following recommendations:
6.1.1 Soil fill shall be placed by the Contractor in layers that, when compacted, should
generally not exceed 8 inches. Each layer shall be spread evenly and shall be
thoroughly mixed during spreading to obtain uniformity of material and moisture
in each layer. The entire fill shall be constructed as a unit in nearly level lifts. Rock
materials greater than 12 inches in maximum dimension shall be placed in
accordance with Section 6.2 or 6.3 of these specifications.
6.1.2 In general, the soil fill shall be compacted at a moisture content at or above the
optimum moisture content as determined by ASTM D 1557-02.
6.1.3 When the moisture content of soil fill is below that specified by the Consultant,
water shall be added by the Contractor until the moisture content is in the range
specified.
6.1.4 When the moisture content of the soil fill is above the range specified by the
Consuhant or too wet to achieve proper compaction, the soil fill shall be aerated by
the Contractor by blading/mixing, or other satisfactory methods until the moisture
content is within the range specified.
GI rev. 04/2009
6.1.5 After each layer has been placed, mixed, and spread evenly, it shall be thoroughly
compacted by the Contractor to a relative compaction of at least 90 percent.
Relative compaction is defined as the ratio (expressed in percent) of the in-place
dry density of the compacted fill to the maximum laboratory dry density as
determined in accordance with ASTM D 1557-02. Compacfion shall be continuous
over the entire area, and compaction equipment shall make sufficient passes so that
the specified minimum relative compaction has been achieved throughout the
entire fill.
6.1.6 Where practical, soils having an Expansion Index greater than 50 should be placed
at least 3 feet below finish pad grade and should be compacted at a moisture
content generally 2 to 4 percent greater than the optimum moisture content for the
material.
6.1.7 Properly compacted soil fill shall extend to the design surface of fill slopes. To
achieve proper compaction, it is recommended that fill slopes be over-built by at
least 3 feet and then cut to the design grade. This procedure is considered
preferable to track-walking of slopes, as described in the following paragraph.
6.1.8 As an alternative to over-building of slopes, slope faces may be back-rolled with a
heavy-duty loaded sheepsfoot or vibratory roller at maximum 4-foot fill height
intervals. Upon completion, slopes should then be track-walked with a D-8 dozer
or similar equipment, such that a dozer track covers all slope surfaces at least
twice.
6.2 Soil-rock fill, as defined in Paragraph 3.1.2, shall be placed by the Contractor in accordance
with the following recommendations:
6.2.1 Rocks larger than 12 inches but less than 4 feet in maximum dimension may be
incorporated into the compacted soil fill, but shall be limited to the area measured
15 feet minimum horizontally from the slope face and 5 feet below finish grade or
3 feet below the deepest utility, whichever is deeper.
6.2.2 Rocks or rock fragments up to 4 feet in maximum dimension may either be
individually placed or placed in windrows. Under certain conditions, rocks or rock
fragments up to 10 feet in maximum dimension may be placed using similar
methods. The acceptability of placing rock materials greater than 4 feet in
maximum dimension shall be evaluated during grading as specific cases arise and
shall be approved by the Consultant prior to placement.
Gl rev. 04/2009
6.2.3 For individual placement, sufficient space shall be provided between rocks to allow
for passage of compaction equipment.
6.2.4 For windrow placement, the rocks should be placed in trenches excavated in
properly compacted soil fill. Trenches should be approximately 5 feet wide and
4 feet deep in maximum dimension. The voids around and beneath rocks should be
filled with approved granular soil having a Sand Equivalent of 30 or greater and
should be compacted by fiooding. Windrows may also be placed utilizing an
"open-face" method in lieu of the trench procedure, however, this method should
first be approved by the Consuhant.
6.2.5 Windrows should generally be parallel to each other and may be placed either
parallel to or perpendicular to the face of the slope depending on the she geometry.
The minimum horizontal spacing for windrows shall be 12 feet center-to-center
with a 5-foot stagger or offset from lower courses to next overlying course. The
minimum vertical spacing between windrow courses shall be 2 feet from the top of
a lower windrow to the bottom of the next higher windrow.
6.2.6 Rock placement, fill placement and flooding of approved granular soil in the
windrows should be continuously observed by the Consultant.
6.3 Rock fills, as defined in Section 3.1.3, shall be placed by the Contractor in accordance with
the following recommendations:
6.3.1 The base of the rock fill shall be placed on a sloping surface (minimum slope of 2
percent). The surface shall slope toward suitable subdrainage outlet facilities. The
rock fills shall be provided with subdrains during construction so that a hydrostatic
pressure buildup does not develop. The subdrains shall be permanently connected
to controlled drainage facilities to control post-construction infiltration of water.
6.3.2 Rock fills shall be placed in lifts not exceeding 3 feet. Placement shall be by rock
trucks traversing previously placed lifts and dumping at the edge of the currently
placed lift. Spreading of the rock fill shall be by dozer to facilitate seating of the
rock. The rock fill shall be watered heavily during placement. Watering shall
consist of water trucks traversing in front of the current rock lift face and spraying
water continuously during rock placement. Compaction equipment with
compactive energy comparable to or greater than that of a 20-ton steel vibratory
roller or other compaction equipment providing suitable energy to achieve the
GI rev. 04/2009
required compaction or defiection as recommended in Paragraph 6.3.3 shall be
utilized. The number of passes to be made should be determined as described in
Paragraph 6.3.3. Once a rock fill lift has been covered with soil fill, no additional
rock fill lifts will be permitted over the soil fill.
6.3.3 Plate bearing tests, in accordance with ASTM D 1196-93, may be performed in
both the compacted 50// fill and in the rock fill to aid in determining the required
minimum number of passes of the compaction equipment. If performed, a
minimum of three plate bearing tests should be performed in the properly
compacted soil fill (minimum relative compaction of 90 percent). Plate bearing
tests shall then be performed on areas of rock fill having two passes, four passes
and six passes of the compaction equipment, respectively. The number of passes
required for the rock fill shall be determined by comparing the results of the plate
bearing tests for the soil fill and the rock fill and by evaluating the deflection
variation with number of passes. The required number of passes of the compaction
equipment will be performed as necessary until the plate bearing deflections are
equal to or less than that determined for the properly compacted soil fill. In no case
will the required number of passes be less than two.
6.3.4 A representative of the Consuhant should be present during rock fill operations to
observe that the minimum number of "passes" have been obtained, that water is
being properly applied and that specified procedures are being followed. The actual
number of plate bearing tests will be determined by the Consultant during grading.
6.3.5 Test pits shall be excavated by the Contractor so that the Consuhant can state that,
in their opinion, sufficient water is present and that voids between large rocks are
properly filled with smaller rock material. In-place density testing will not be
required in the rock fills.
6.3.6 To reduce the potential for "piping" of fines into the rock fill from overlying soil
fill material, a 2-foot layer of graded filter material shall be placed above the
uppermost lift of rock fill. The need to place graded fifter material below the rock
should be determined by the Consultant prior to commencing grading. The
gradation of the graded fiher material will be determined at the time the rock fill is
being excavated. Materials typical of the rock fill should be submitted to the
Consuhant in a timely manner, to allow design of the graded fiher prior to the
commencement of rock fill placement.
6.3.7 Rock fill placement should be continuously observed during placement by the
Consuhant.
GI rev. 04/2009
7. OBSERVATION AND TESTING
7.1 The Consultant shall be the Owner's representative to observe and perform tests during
clearing, grubbing, filling, and compaction operations. In general, no more than 2 feet in
vertical elevation of soil or soil-rock fill should be placed without at least one field denshy
test being performed within that interval. In addition, a minimum of one field density test
should be performed for every 2,000 cubic yards of soil or soil-rock fill placed and
compacted.
7.2 The Consuhant should perform a sufficient distribution of field density tests of the
compacted soil or soil-rock fill to provide a basis for expressing an opinion whether the fill
material is compacted as specified. Density tests shall be performed in the compacted
materials below any disturbed surface. When these tests indicate that the density of any
layer of fill or portion thereof is below that specified, the particular layer or areas
represented by the test shall be reworked until the specified density has been achieved.
7.3 During placement of rock fill, the Consultant should observe that the minimum number of
passes have been obtained per the criteria discussed in Section 6.3.3. The Consultant
should request the excavation of observation phs and may perform plate bearing tests on
the placed rock fills. The observation pits will be excavated to provide a basis for
expressing an opinion as to whether the rock fill is properly seated and sufficient moisture
has been applied to the material. When observations indicate that a layer of rock fill or any
portion thereof is below that specified, the affected layer or area shall be reworked until the
rock fill has been adequately seated and sufficient moisture applied.
7.4 A settlement monitoring program designed by the Consultant may be conducted in areas of
rock fill placement. The specific design of the monkoring program shall be as
recommended in the Conclusions and Recommendations section of the project
Geotechnical Report or in the final report of testing and observation services performed
during grading.
7.5 The Consuhant should observe the placement of subdrains, to verify that the drainage
devices have been placed and constructed in substantial conformance with project
specifications.
7.6 Testing procedures shall conform to the following Standards as appropriate:
Gl rev. 04/2009
7.6.1 Soil and Soil-Rock Fills:
7.6.1.1 Field Density Test, ASTM D 1556-02, Density of Soil In-Place By the
Sand-Cone Method.
7.6.1.2 Field Density Test, Nuclear Method, ASTM D 6938-08A, Density of Soil
and Soil-Aggregate In-Place by Nuclear Methods (Shallow Depth).
7.6.1.3 Laboratory Compaction Test, ASTM D 1557-02, Moisture-Density
Relations of Soils and Soil-Aggregate Mixtures Using 10-Pound
Hammer and 18-Inch Drop.
7.6.1.4. Expansion Index Test, ASTM D 4829-03, Expansion Index Test.
7.6.2 Rock Fills
7.6.2.1 Field Plate Bearing Test, ASTM D 1196-93 (Reapproved 1997)
Standard Method for Nonreparative Static Plate Load Tests of Soils and
Flexible Pavement Components, For Use in Evaluation and Design of
Airport and Highway Pavements.
8. PROTECTION OF WORK
8.1 During construction, the Contractor shall properly grade all excavated surfaces to provide
poshive drainage and prevent ponding of water. Drainage of surface water shall be
controlled to avoid damage to adjoining properties or to finished work on the she. The
Contractor shall take remedial measures to prevent erosion of freshly graded areas until
such time as permanent drainage and erosion control features have been installed. Areas
subjected to erosion or sedimentation shall be properly prepared in accordance with the
Specifications prior to placing addhional fill or structures.
8.2 After completion of grading as observed and tested by the Consultant, no further
excavation or filling shall be conducted except in conjunction whh the services of the
Consultant.
Gl rev. 04/2009
9. CERTIFICATIONS AND FINAL REPORTS
9.1 Upon completion of the work. Contractor shall furnish Owner a certification by the Civil
Engineer stating that the lots and/or building pads are graded to within 0.1 foot vertically of
elevations shown on the grading plan and that all tops and toes of slopes are within 0.5 foot
horizontally of the positions shown on the grading plans. After installation of a section of
subdrain, the project Civil Engineer should survey its location and prepare an as-built plan
of the subdrain location. The project Civil Engineer should verify the proper outlet for the
subdrains and the Contractor should ensure that the drain system is free of obstructions.
9.2 The Owner is responsible for furnishing a final as-graded soil and geologic report
satisfactory to the appropriate governing or accepting agencies. The as-graded report
should be prepared and signed by a California licensed Civil Engineer experienced in
geotechnical engineering and by a California Certified Engineering Geologist, indicating
that the geotechnical aspects of the grading were performed in substantial conformance
with the Specifications or approved changes to the Specifications.
GI rev. 04/2009
LIST OF REFERENCES
1. Boore, D. M., and G. M Atkinson (2006), Boore-Atkinson NGA Ground Motion Relations for
the Geometric Mean Horizontal Component of Peak and Spectral Ground Motion
Parameters, Report Number PEER 2007/01, May 2007.
2. Brain S. J. Chiou and Robert R. Youngs, A A^GA Model for the Average Horizontal
Component of Peak Ground Motion and Response Spectra, preprint for article to be
published in NGA Special Edition for Earthquake Spectra, Spring 2008.
3. Califomia Department of Conservation, Division of Mines and Geology, Probabilistic
Seismic Hazard Assessment for the State of Califomia, Open File Report 96-08, 1996.
4. Califomia Geological Survey, Seismic Shaking Hazards in Califomia, Based on the
USGS/CGS Probabilistic Seismic Hazards Assessment (PSHA) Model, 2002 (revised April
2003). 10% probability of being exceeded in 50 years.
http://redirect.conservation.ca.gov/cgs/rghm/pshamap/pshamain.html
5. Campbell, K. W., Y. Bozorgnia, NGA Ground Motion Model for the Geometric Mean
Horizontal Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response
Spectra for Periods Ranging from 0.01 to 10 s. Preprint of version submitted for publication
in the NGA Special Volume of Earthquake Spectra, Volume 24, Issue 1, pages 139-171,
Febmary 2008.
6. Geotechnical Review, Moonstone, Dove Lane and El Camino Real, Carlsbad, Califomia,
prepared by Geocon Incorporated, dated December 15, 2010 (Project No. 07193-32-03).
7. Kennedy, M. P. and S. S. Tan, 2005, Geologic Map ofthe Oceanside 30'x60' Quadrangle,
Califomia, USGS Regional Map Series, Scale 1:100,000.
8. Risk Engineering, EZ-FRISK, 2008.
9. Update Geotechnical Investigation, Levatino Project Northwest Comer of Dove Lane and El
Camino Real, Carlsbad, Califomia, prepared by Geocon Incorporated, dated January 25,
2007 (Project No. 07193-42-02).
10. USGS computer program, 2002 Interactive Deaggregation,
http://eqint.cr.usgs.gov/deaggint/2002/index.php.
11. USGS computer program. Seismic Hazard Curves and Uniform Hazard Response Spectra.
12. United States Geological Survey, 7.5 minute Quadrangle Series, Encinitas Quadrangle, 1968.
13. Unpublished reports, aerial photographs and maps on file with Geocon Incorporated.
Project No. 07193-32-03 April 25, 2011
Revised July 14, 2011