HomeMy WebLinkAboutSDP 2019-0014; CARLSBAD OAKS NORTH LOT 2; UPDATE GEOTECHNICAL REPORT - CARLSBAD OAKS NORTH BUSINESS PARK - LOT 2, CARLSBAD, CALIFORNIA; 2019-11-01UPDATE
GEOTECHNICAL REPORT
CARLSBAD OAKS NORTH BUSINESS
PARK-LOT 2
CARLSBAD, CALIFORNIA
PREPARED FOR
MERIDIAN PROPERTIES
CARLSBAD, CALIFORNIA
NOVEMBER 1, 2019
PROJECT NO. 06442-32-32
GEOCON
INCORPORATED
GEOTECHNICAL • ENVIRONMENTAL. MATERIALS (107)
Project No. 06442-32-32
November 1, 2019
Meridian Properties r
3405 Highland Drive, Suite 100
Carlsbad, California 92008
Attention: Mr. Mike Kalscheur
Subject: UPDATE GEOTECHNICAL REPORT
CARLSBAD OAKS NORTH BUSINESS PARK - LOT 2
CARLSBAD, CALIFORNIA
Dear Mr. Kalscheur:
In accordance with your authorization, we have prepared an update geotechnical report for the
proposed development of a parking lot on Lot 2 of Carlsbad Oaks North Business Park. The
accompanying report presents the findings of our study and our conclusions and recommendations
pertaining to the geotechnical aspects of project development.
We understand that the project includes fine grading the existing sheet-graded pad to support a paved
parking lot with the associated underground and surface improvements. Based on the results of this
study, it is our opinion that the site can be developed as planned, provided the recommendations of
this report are followed.
If there are any questions regarding this update report, or if we may be of further service, please
contact the undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
Trevor E. Myers
RCE 63773
TEM:DBE:dmc NcL RCE83773
(4) Addressee
David B. Evans
CEG1860'0
/ DAVID B. I ENS
CL NO.1860
1* CERTIFIED \cp ENGINEERING
GEOLOGIST
6960 Flanders Drive 0 San Diego, California 92121-2974 0 Telephone 858.558.6900 0 Fax 858.558.6159
TABLE OF CONTENTS
PURPOSE AND SCOPE.................................................................................................................
SITE AND PROJECT DESCRIPTION...........................................................................................
SOIL AND GEOLOGIC CONDITIONS........................................................................................2
3.1 Compacted Fill (Qcf) ............................................................................................................. 2
3.2 Point Loma Formation (Kp)..................................................................................................2
3.3 Santiago Formation (Tsa)......................................................................................................2
GROUNDWATER..........................................................................................................................3
S. GEOLOGIC HAZARDS .................................................................................................................3
5.1 Faulting and Seismicity.........................................................................................................3
5.2 Landslides ............ . ................................................................................................................. 5
5.3 Liquefaction and Seismically Induced Settlement................................................................5
5.4 Tsunamis and Seiches............................................................................................................5
6. CONCLUSIONS AND RECOMMENDATIONS ..........................................................................6
6.1 General ..................................................................................................................................6
6.2 Soil and Excavation Characteristics ...................................................................................... 6*
6.3 Corrosion ................................................... . ........................................................................... 7
6.4 Seismic Design Criteria.........................................................................................................8
6.5 Grading ................................................................................................................................. 10
6.6 Slopes..................................................................................................................................11
6.7 Preliminary Pavement Recommendations - Flexible and Rigid.........................................12
6.8 Storm Water Management .................................................................................................... 14
6.9 Slope Maintenance..............................................................................................................15
6.10 Site Drainage and Moisture Protection................................................................................15
6.11 Grading and Foundation Plan Review.................................................................................16
LIMITATIONS AND UNIFORMITY OF CONDITIONS
MAPS AND ILLUSTRATIONS
Figure 1, Vicinity Map
Figure 2, Geologic Map (map pocket)
Figure 3, Geologic Cross-Section A-A'
APPENDIX A
RESULTS OF LABORATORY TESTING
Table A-I, Summary of Laboratory Expansion Index, Resistance Value (R-Value),
and Water-Soluble Sulfate Test Results
APPENDIX B
STORM WATER MANAGEMENT
APPENDIX C
RECOMMENDED GRADING SPECIFICATIONS
UPDATE GEOTECHNICAL REPORT
1. PURPOSE AND SCOPE
This report presents the results of an update geotechnical study for a proposed parking lot
development in Carlsbad Oaks North Business Park Lot 2 in Carlsbad, California (see Vicinity Map,
Figure 1). The purpose of this update report was to provide specific geotechnical recommendations in
accordance with the 2016 California Building Code (CBC) pertaining to development of the property
as proposed.
The scope of our study included a site visit to observe whether the lot was essentially the same as it
was upon the completion of mass grading operations, and a review of the reports titled Final Report of
Testing and Observation Services During Site Grading, Carlsbad Oaks North Business Park, Phase 1,
Lots 1 through 9, Carlsbad, California, prepared by Geocon Incorporated, dated August 30, 2006
(Project No. 06442-32-04A) and Addendum to Final Report of Testing and Observation Services
During Site Grading, Carlsbad Oaks North Business Park - Phase 1, Lots 2 Through 6, Carlsbad,
California, prepared by Geocon Incorporated, dated December 26, 2007 (Project No. 06442-32-04A)..
The descriptions of the soil and geologic conditions and proposed development described herein is
based on review of the above referenced report and observations made during mass grading operations
for the overall Carlsbad Oaks Business Park development.
2. SITE AND PROJECT DESCRIPTION
Lot 2 is a sheet-graded pad located south of the intersection of Faraday Avenue and El Fuerte Street,
in the City of Carlsbad, California (see Vicinity Map, Figure 1). The pad was created circa 2006-2007
during the overall mass grading of the Carlsbad Oaks North Business Phase 1. The as-graded
condition of the lot generally consists of compacted fill underlain by the Point Loma and Santiago
Formations. These formations are exposed at the surface along the south side of the lot, as shown on
the Geologic Map, Figure 2. The fill thickness across the pad ranges from approximately 3 to 16 feet.
The finish grade soils exhibit a "low" to "high" expansion potential and a "moderate" to "severe"
sulfate exposure rating. A drained buttress fill was constructed along the south side of the lot to reduce
the potential for slope instability due to the presence of weak claystone and siltstone materials and
extensive seepage. Cross-Section A-A' is presented as Figure 3.
The site plan indicates that development will consist of fine grading the site to support a parking lot
and associated utilities. The descriptions contained herein are based upon the site reconnaissance and a
review of the referenced report and plans. If project details vary significantly from those outlined
herein, Geocon Incorporated should be notified for review and possible revisions to this report prior to
final design submittal. .
Project No. 06442-32-32 - I - November 1, 2019
3. SOIL AND GEOLOGIC CONDITIONS
Compacted fill and Santiago and Point Loma Formations underlie the site. Descriptions of these units
are presented below. The existing as-graded geologic conditions are presented on Figure 2.
3.1 Compacted Fill (Qcf)
Compacted fill placed during grading operations generally consisted of silty fine sand, silty/clayey fine
to coarse sand, and fine sandy silt, exhibits a "low" to "medium" expansion potential, and "moderate"
to "severe" sulfate exposure. The compacted fill was placed at a minimum relative compaction of 90
percent at appropriate moisture contents. The approximate base elevation of the fill across the site is
shown on the Geologic Map, Figure 2.
3.2 Point Loma Formation (Kp)
Cretaceous-age Point Loma Formation underlies the compacted fill and is exposed along the southern
portion of the pad. The Point Loma Formation consists of relatively flat-lying siltstones and fine
grained sandstones and may exhibit highly cemented zones that can result in excavation difficulty
during fine grading. Although blasting is not anticipated, moderate to heavy ripping may be necessary
to facilitate excavations extending into this material. Consideration should be given to undercutting
this formation if exposed within 3 feet of planned finish grade to facilitate excavations for shallow
underground utilities.
3.3 Santiago Formation (Tsa)
The Eocene-age Santiago Formation is exposed at the surface along the southern portion of the sheet-
graded pad. In general, the Santiago Formation consists of relatively flat-lying claystone, siltstone, and
sandstone units. Weak, waxy claystories and thinly laminated siltstones, claystones, and sandstones are
present within this unit and have been encountered at various elevations throughout the overall Carlsbad
Oaks Business Park. With the exception of the sandier portions of the Santiago Formation, materials
derived from this unit typically possess a medium to high expansion potential with low to moderate
shear strength. The Santiago Formation has a potential to transmit seepage through relatively pervious
layers within the formation.
The Santiago Formation may possess highly cemented zones that result in excavation difficulty during
grading and construction of site improvements (e.g., underground utility lines and building foundations).
Although blasting is not expected, moderate to heavy ripping may be necessary in portions of this
formation to facilitate excavation. Generation of oversize materials requiring special handling and
placement techniques should also be expected. Consideration should be given to undercutting cemented
zones if they are found within 3 feet of finish grade. Undercutting during fine grading will help reduce
the potential for excavation difficulty during the construction of site improvements.
Project No. 06442-32-32 -2- November 1, 2019
4. GROUNDWATER
Groundwater was not observed during the grading operations, however, a drained buttress fill was
constructed along the southern portion of the lot to mitigate heavy seepage and weak materials
exposed in the Santiago Formation. Groundwater is not anticipated to impact proposed project
development, however, perched water conditions may develop following periods of heavy
precipitation or prolonged irrigation. In the event that surface seeps develop, shallow subdrains may be
necessary to collect and convey the seepage to a suitable outlet facility.
5. GEOLOGIC HAZARDS
5.1 Faulting and Seismicity
Based on our previous observations during mass grading and a review of published geologic maps and
reports, the site is not located on any known "active," "potentially active" or "inactive" fault traces as
defined by the California Geological Survey (CGS). An inactive fault trace was observed on the
property during original grading as shown on the Geologic Map, Figure 2.
The Newport-Inglewood and Rose Canyon Fault zones, located approximately 8 miles west of the site,
are the closest known active faults. The CGS considers a fault seismically active when evidence
suggests seismic activity within roughly the last 11,000 years. The CGS has included portions of the
Rose Canyon Fault zone within an Alquist-Priolo Earthquake Fault Zone.
According to the computer program EZ-FRISK (Version 7.65), 10 known active faults are located
within a search radius of 50 miles from the property. We used the 2008 USGS fault database that
provides several models and combinations of fault data to evaluate the fault information. The nearest
active faults are the Newport-Inglewood and Rose Canyon Fault Zone, located approximately 8 miles
west of the site and is the dominant source of potential ground motion. Earthquakes that might occur
on the Newport-Inglewood and Rose Canyon Fault Zone or other faults within the southern California
and northern Baja California area are potential generators of significant ground motion at the site. The
estimated maximum earthquake magnitude and peak ground acceleration for the Newport-Inglewood
Fault are 7.5 and 0.51g, 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 USGS 2008,
Campbell-Bozorgnia (2008) NGA USGS 2008, and Chiou-Youngs (2008) NGA acceleration-
attenuation relationships.
Project No. 06442-32-32 -3 - November 1, 2019
TABLE 5.1.1
DETERMINISTIC SEISMIC SITE PARAMETERS
Fault Name
Distance
from Site
(miles)
Maximum
Earthquake
Magnitude
(Mw)
Peak Ground Acceleration
Boore-
Atkinson
2008 (g)
Campbell-
Bozorgnia
2008 (g)
Chiou-
Youngs
2008 (g)
Newport-Inglewood 8 7.5 0.47 0.41 0.52
Rose Canyon 8 6.9 0.39 0.37 0.41
Elsinore 20 7.85 0.33 0.22 0.29
Coronado Bank 23 7.4 0.25 0.17 0.20
Palos Verdes Connected 23 7.7 0.28 0.19 0.24
Earthquake Valley 39 6.8 0.12 0.09 0.07
Palos Verdes 39 7.3 0.15 0.11 0.11
San Joaquin Hills 39 7.1 0.14 0.13 0.11
San Jacinto 45 7.8 0.17 0.12 0.15
Chino 50 6.8 0.09 0.07 0.06
We performed a site-specific probabilistic seismic hazard analysis using the computer program
EZ-FRISK (Version 7.65). Geologic parameters not addressed in the deterministic analysis are
included in this analysis. The program operates under the assumption that the occurrence rate of
earthquakes on each mappable Quaternary fault is proportional to the faults slip rate. The program
accounts for fault rupture length as a function of earthquake magnitude, and site acceleration estimates
are made using the earthquake magnitude and distance from the site to the rupture zone. The program
also accounts for uncertainty in each of following: (1) earthquake magnitude, (2) rupture length for a
given magnitude, (3) location of the rupture 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 2008,
Campbell-Bozorgnia (2008) NGA USGS 2008, and Chiou-Youngs (2008) NGA in the analysis.
Table 5.1.2 presents the site-specific probabilistic seismic hazard parameters including acceleration-
attenuation relationships and the probability of exceedence.
Project No. 06442-32-32 -4- November I, 2019
TABLE 5.1.2
PROBABILISTIC SEISMIC HAZARD PARAMETERS
Probability of Exceedence
Peak Ground Acceleration
Boore-Atkinson,
2008 (g)
Campbell-Bozorgnia,
2008 (g)
Chiou-Youngs,
2008 (g)
2%ina50 Year Period 0.41 0.40 0.45
5% in a 50 Year Period 0.31 0.29 0.32
10% in a 50 Year Period 0.24 0.22 0.23
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
mof ion and the soil conditions underlying the site. Seismic design of the structures should be evaluated
in accordance with the California Building Code (CBC) guidelines currently adopted by the City of
Carlsbad.
5.2 Landslides
No landslides were encountered within the site or mapped within the immediate areas influencing the
project development. However, an existing natural slope exposing Santiago Formation is present to the
south of the sheet-graded pad. A stabilized fill slope was constructed along the lower portions of this
slope to mitigate heavy seepage and potential for slope instability. The Santiago Formation is a
landslide prone formation. The risk associated with landslide hazards is low to moderate.
5.3 Liquefaction and Seismically Induced Settlement
The risk associated with liquefaction and seismically induced settlement hazard at the subject project
is very low due to the existing dense compacted fill, very dense nature of the bedrock, and the lack of
a permanent, shallow groundwater table.
5.4 Tsunamis and Seiches
The risk associated with tsunamis and seiches hazard at the project is very low due to the large distance
from the coastline, the absence of an upstream body of water and the lot located at an elevation of
approximately 260 feet above Mean Sea Level (MSL).
Project No. 06442-32-32 -5 - November 1, 2019
6. CONCLUSIONS AND RECOMMENDATIONS
6.1 General
6. .1 No soil or geologic conditions exist at the site that would preclude the development of the
property as planned, provided the recommendations of this report are followed.
6.1.2 The site is underlain by compacted fill, Santiago Formation, and the Point Loma Formation.
The approximate base of the compacted fill is shown on the Geologic Map, Figure 2. The
compacted fill was placed under the observation and testing of Geocon Incorporated and
exhibited a minimum relative compaction of 90 percent at appropriate moisture contents, a
"low" to "high" expansion potential, and "moderate" to "severe" water soluble sulfate
content. The compacted fill, Santiago Formation, and Point Loma Formation, are considered
suitable to support additional fill or structural loads.
6.1.3 It is anticipated that the majority of the proposed excavations will require moderate to heavy
ripping with conventional heavy-duty equipment. Blasting is not expected. In addition,
heavy ripping may generate oversize materials that will require special handling and fill
placement procedures. Oversize materials should be placed in accordance with Appendix C
of this report.
6.1.4 Recommendations presented herein assume that the site will be graded such that soil with an
Expansion Index (El) of 90 or less will be present to a minimum depth of 3 feet below finish
grade. If soil with an El greater than 90 is exposed near finish grade, modifications to the
recommendations presented herein may be-required.
6.2 Soil and Excavation Characteristics
6.2.1 The finish-grade soils tested during the mass grading operations indicate that the prevailing
soil conditions within 3 feet of grade are classified as exhibiting a "low" to "high"
expansion potential as defined by 2016 California Building Code (CBC) Section 1803.5.3.
A summary of the laboratory expansion index test results performed during this study are
presented in Appendix A. Table 6.2 presents soil classifications based on the expansion
index.
Project No. 06442-32-32 -6- November 1, 2019
TABLE 6.2
EXPANSION CLASSIFICATION BASED ON EXPANSION INDEX
Expansion Index (El) ASTM 4829
Expansion Classification
2016 CBC
Expansion Classification
0-20 Very Low Non-Expansive
21-50 Low
Expansive
Very High
51 -90 Medium
91-130 High
Greater Than 130
6.2.2 The existing compacted fill soils should generally require light to moderate effort toexcavate
using conventional heavy-duty grading equipment. Excavations for underground
improvements that may extend through the compacted fill and into the Point Loma or Santiago
Formations may require very heavy effort. The need to utilize blasting techniques to facilitate
planned excavations and trenching operations may not be necessary; however, excavation
difficulty should be anticipated.
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 rules and regulations
in order to maintain safety and maintain the stability of adjacent existing improvements.
6.3 Corrosion
6.3.1 We performed laboratory tests on samples of the site materials to evaluate the percentage of
water-soluble sulfate. Results from the laboratory water-soluble sulfate content testing are
presented in Appendix A and indicate that the on-site materials at the locations tested
possess a "Severe" and "S2" sulfate exposure to concrete structures as defined by 2016 CBC
Section 1904 and AC! 318-14 Chapter 19. Table 6.3 presents a summary of concrete
requirements set forth by 2016 CBC Section 1904 and ACE 318.
Project No. 06442-32-32 -7- November 1, 2019
TABLE 6.3
REQUIREMENTS FOR CONCRETE EXPOSED
TO SULFATE-CONTAINING SOLUTIONS
Water-Soluble Maximum Minimum
Sulfate Exposure Sulfate (SO4) Cement Type Water to Compressive
Severity Class Percent (ASTM C 150) Cement Ratio Strength
by Weight by Weight' (psi)
Not Applicable SO .SO4<0.10 No Type
Restriction n/a 2,500
Moderate SI 0.I0<SO4<0.20 II 0.50 4,000
Severe - S2 0.20<S0452.00 V 0.45 4,500
Very Severe S3 SO4>2.00 V+Pozzotan
or Slag
0.45 4,500
'Maximum water to cement ratio limits do not apply to lightweight concrete.
6.3.2 The presence of water-soluble sulfates is not a visually discernible characteristic; therefore,
other soil samples from the site could yield different concentrations. Additionally, over time
landscaping activities (i.e., addition of fertilizers and other soil nutrients) may affect the
concentration.
6.3.3 Geocon Incorporated does not practice in the field of corrosion engineering. Therefore,
further evaluation by a corrosion engineer may be performed if improvements that could be
susceptible to corrosion are planned.
6.4 Seismic Design Criteria
6.4.1 We used the Structural Engineers Association of California (SEAOC) and Office of Statewide
Health Planning and Development (OSI-IPD) web application Seismic Design Maps
(https://seismicmaps.org). Table 6.4.1 summarizes site-specific design criteria obtained from
the 2016 California Building Code (CBC; Based on the 2015 International Building Code
[IBC] and ASCE 7-10), Chapter 16 Structural Design, Section 1613 Earthquake Loads. The
short spectral response uses a period of 0.2 seconds. The values presented in Table 6.4.1 are
for the risk-targeted maximum considered earthquake (MCER). Based on soil conditions, the
proposed structures supported on compacted fill over formational materials should be
designed using a Site Class C. We evaluated the Site Class based on the discussion in
Section 1613.3.2 of the 2016 CBC and Table 20.3-1 of ASCE 7-10.
Project No. 06442-32-32 - 8 - November 1, 2019
TABLE 6.4.1
2016 CBC SEISMIC DESIGN PARAMETERS
Parameter Value 2016 CBC Reference
Site Class C Section 16 13.3.2
MCER Ground Motion Spectral 1.043g Figure 1613.3.1(1) Response Acceleration - Class B (short), Ss
MCER Ground Motion Spectral 0.405g Figure 1613.3.1(2) Response Acceleration - Class B (1 sec), Si
Site Coefficient, FA 1.000 Table 1613.3.3(1)
Site Coefficient, Fv 1.395 Table 16 13.3.3(2)
Site Class Modified MCER Spectral 1.043g Section 1613.3.3 (Eqn 16-37) Response Acceleration (short), SMS
Site Class Modified MCER Spectral 0.565g Section 1613.3.3 (Eqn 16-38) Response Acceleration (1 sec), Sm,
5% Damped Design Spectral 0.696g Section 16 13.3.4 (Eqn 16-39) Response Acceleration (short), SDS
5% Damped Design Spectral 0.376g Section 16 13.3.4 (Eqn 16-40) Response Acceleration (1 sec), SDI
6.4.2 Table 6.4.2 presents additional seismic design parameters for projects located in Seismic
Design Categories of D through F in accordance with ASCE 7-10 for the mapped maximum
considered geometric mean (MCEc).
TABLE 6.4.2
2016 CBC SITE ACCELERATION PARAMETERS
Parameter Site Class C ASCE 7-10 Reference
Mapped MCEG Peak Ground Acceleration, PGA 0.398g Figure, 22-7
Site Coefficient, FPGA 1.002 Table 11.8-1
Site Class Modified MCE
Peak Ground Acceleration, PGAM 0.399g Section 11.8.3 (Eqn 11.8-1)
6.4.3 Conformance to the criteria for seismic design does not constitute any guarantee or
assurance that significant structural damage or ground failure will not occur in the event of a
maximum level earthquake. The primary goal of seismic design is to protect life and not to
avoid all damage, since such design may be economically prohibitive.
Project No. 06442-32-32 -9- November 1, 2019
6.5 Grading
6.5.1 Grading should be performed in accordance with the Recommended Grading Specifications
contained in Appendix C. Where the recommendations of Appendix C conflict with this
section of the report, the recommendations of this section take precedence.
6.5.2 Prior to commencing grading, a preconstruction conference should be held at the site with
the owner or developer, grading contractor, civil engineer, and geotechnical engineer in
attendance. Special soil handling and the fine grading plan can be discussed at that time.
6.5.3 Grading should be performed in conjunction with the observation and compaction testing
services of Geocon Incorporated. Fill soil should be observed on a full-time basis during
placement and, tested to check in-place dry density and moisture content.
6.5.4 Site preparation should begin with the removal of all deleterious material and vegetation in
areas of proposed grading. The depth of removal should be such that soil exposed in cut
areas or soil to be used as fill is relatively free of organic matter. Material generated during
stripping and/or site demolition should be exported from the site.
6.5.5 Loose or soft accumulated soils in the temporary detention basin will need to be removed
and compacted prior to filling the basin, if needed. Abandoned storm drain pipes associated
with the temporary basin should also be removed and the resulting excavation backfilled in
accordance with the recommendations presented herein.
6.5.6 Areas to receive fill should be scarified to a depth of at least 12 inches, moisture conditioned
as necessary, and compacted to at least 90 percent relative compaction prior to placing
additional fill. In areas where proposed cuts into existing fills are less than 12 inches, the
resulting finish-grade soils should be scarified, moisture conditioned as necessary, and
compacted to at least 90 percent of the laboratory maximum dry density at or slightly above
optimum moisture content. Near-surface soils may need to be processed to greater depths
depending on the amount of drying or wetting that has occurred within the soils since the
initial sheet grading of the pad The actual extent of remedial grading should be determined
in the field by the geotechnical engineer or engineering geologist. Overly wet surficial soils,
if encountered, will need to be removed to expose existing dense, moist compacted fill or
formational materials. The wet soils will require drying and/or mixing with drier soils to
facilitate proper compaction.
6.5.7 Consideration may be given to undercutting the Santiago and Point Loma Formations
exposed along the southern portion of the pad for ease of excavating utility trenches or any
light pole footings. The undercutting should extend at least 1-foot below the deepest utility
Project No. 06442-32-32 _10- November 1, 2019
trench or foundation in this area. The need for undercutting can also be evaluated during
fine grading.
6.5.8 After site preparation and removal of unsuitable soils as described above is performed, the
site should then be brought to final subgrade elevations with structural fill compacted in
layers. In general, soils native to the site are suitable for re-use as fill provided vegetation,
debris and other deleterious matter are removed. Layers of fill should be no thicker than will
allow for adequate bonding and compaction. Fill, including backfill and scarified ground
surfaces, should be compacted to at least 90 percent of laboratory maximum dry density as
determined by ASTM D 1557, at or slightly above optimum moisture content. The project
geotechnical engineer may consider fill materials below the recommended minimum
moisture content unacceptable and may require additional moisture conditioning prior to
placing additional fill.
6.5.9 For areas to receive fill and undercut areas, rock fragments greater than 6 inches in
maximum dimension should not be placed within three feet of subgrade in
driveways/parking areas. Rock fragments greater than 12 inches in maximum dimension
should be placed at least 5 feet below finish grade and least one foot below deepest planned
utility.
6.5.10 Imported soils (if required), should consist of granular very low to low expansive soils
(El < 50). Prior to importing the soil, samples from proposed borrow areas should be
obtained and subjected to laboratory testing to check if the material conforms to the
recommended criteria. The import soil should be free of rock greater than six inches and
construction debris. Laboratory testing typically takes up to four days to complete. The
grading contractor needs to coordinate the laboratory testing into the schedule to provide
sufficient time to allow for completion of testing prior to importing materials.
6.6 Slopes
6.6.1 No new significant fill slopes are planned during the fine grading.
6.6.2 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. Slope planting should generally consist of
drought tolerant plants having a variable root depth. Slope watering should be kept to a
minimum to just support the plant growth.
Project No. 06442-32-32 - 11 - November 1, 2019
6.7 Preliminary Pavement Recommendations - Flexible and Rigid
6.7.1 The following preliminary pavement design sections are based on. laboratory resistance
value (R-Value) test results performed on a representative on-site soil sample. The civil
engineer should provide traffic indices (TI) for use in final pavement design. The
preliminary sections presented herein are for budgetary estimating purposes only. Based on
the laboratory test results, an R-Value of 20 has been assumed. The final pavement sections
will be provided .after the grading operations are completed, subgrade soils are exposed,
laboratory R-Value testing is performed on the subgrade soils and traffic indices are
provided for our use.
6.7.2 The preliminary pavement section recommendations are for areas that will be used as
passenger vehicle parking and, car/light truck and heavy truck driveways. We evaluated the
flexible pavement sections in accordance with State of California, Department of
Transportation (Caltrans) Highway Design Manual. Rigid pavement sections consisting of
Portland cement concrete (PCC) are based on methods suggested by the American Concrete
Institute Guide for Design and Construction of Concrete Parking Lots (ACI 330R-08). The
structural sections presented herein are also in accordance with City of Carlsbad minimum
requirements for private commercial/industrial developments. Table 6.7 summarizes
preliminary pavement sections.
TABLE 6.7.
PRELIMINARY PAVEMENT DESIGN SECTIONS
S Estimated Asphalt Class 2
Aggregate Base PCC
Location Traffic Concrete beneath Asphalt Section
Index ITIl* (inches)** Concrete (inches) (inches)
Automobile Parking Stalls 4.5 4 4 5
Automobile! 5.0 4 5 6
Light truck Driveways
Heavy /Trash Truck 6.0 4 9 7 Driveways/FireLane
.
Trash Enclosure Apron N/A N/A N/A 75**
*Civil engineer should provide TI for final pavement design.
**City of Carlsbad minimums for Private Commercial/Industrial developments.
Project No. 06442-32-32 - 12 - November 1, 2019
6.7.3 We used the following parameters in design of the PCC pavement:
Modulus of subgrade reaction, k = 100 pci
Modulus of rupture for concrete, MR = 500 psi'
Traffic Category = A, B, and C
Average daily truck traffic, ADTT = 10 (Cat A) and 25 (Cat B), 100 (Cat C)
Reinforcing: No. 3 bars placed 24 inches O.C. each way and placed at center of slab.
*pci = pounds per cubic inch.
= pounds per square inch.
6.7.4 Asphalt concrete should conform to Section 203-6 of the Standard Specifications for Public
Works Construction (Greenbook). Class 2 aggregate base should conform to Section 26-
1.02B of Caltrans with a %-inch maximum size aggregate.
6.7.5 Prior to placing base material and PCC pavement, subgrade soils should be scarified,
moisture conditioned and compacted to a dry density of at least 95 percent of the laboratory
maximum dry density near or slightly above optimum moisture content in accordance with
ASTM D- 1557. The depth of compaction should be at least 12 inches. Base material should
be compacted to a dry density of at least 95 percent of the laboratory maximum dry density
near or slightly abàve optimum moisture content. Asphalt concrete should be compacted to
at least 95 percent of the laboratory Hveem density in accordance with ASTM D 2726.
6.7.6 Loading aprons such as trash bin enclosures and heavy truck areas, if proposed, should
utilize Portland cement concrete as presented in Table 6.7 above: The concrete loading area
should extend out such that both the front and rear wheels of the truck will be located on
reinforced concrete pavement when loading and unloading.
6.7.7 The following recommendations are being provided for PCC pavement areas.
A thickened edge or integral curb should be constructed on the outside of concrete
(PCC) 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, at
the slab edge and taper back to the recommended slab thickness 3 feet behind the face
of the slab (e.g., a 7-inch-thick slab would have a 9-inch-thick edge).
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 15 feet (e.g., a 7-inch-thick slab would have a 15-foot spacing
pattern) 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 AC! report.
Project No. 06442-32-32 - 13- November 1, 2019
Construction joints should be provided at the interface between areas of concrete
placed at different times during construction. Doweling is recommended between the
joints in pavements subjected to heavy truck traffic. Dowels should meet the
recommendations in the referenced AC! guide and should be provided by the project
structural engineer.
6.7.8 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 structures. 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 six inches
below the level of the base materials.
6.8 Storm Water Management
6.8.1 We understand that low-impact development (LID) integrated management practices
(IMP's) are included in the design of the subject site.
6.8.2 If not property constructed, 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 constructed. Based on our
experience with similar soil and shallow bedrock conditions, infiltration IMP's are
considered infeasible due to the poor percolation characteristics. 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.
6.8.3 Due to site soil and geologic conditions, a heavy duty, non-permeable liner is recommended
beneath any hydro-modification areas or IMP's where water infiltration into the underlying
soils is planned. If permeable payers are planned, the design should include a subdrain to
prevent subgrade saturation and pavement distress. The strength and thickness of the
membrane, and construction 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
Project No. 06442-32-32 -14- November 1, 2019
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.
6.8.4 A stormwater infiltration feasibility investigation, is included in Appendix B.
6.9 Slope Maintenance
6.9.1 Slopes that are steeper than 3:1 (horizontal:vertical) may, under conditions that are both
difficult to prevent and predict, be susceptible to near-surface (surficial) slope instability.
The instability is typically limited to the outer 3 feet of a portion of the slope and usually
does not directly impact the improvements on the pad areas above or below the slope. The
occurrence of surficial instability is more prevalent on fill slopes and is generally preceded
by a period of heavy rainfall, excessive irrigation, or the migration of subsurface seepage.
The disturbance and/or loosening of the surficial soils, as might result from root growth, soil
expansion, or excavation for irrigation lines and slope planting, may also be a significant
contributing factor to surficial instability. It is, therefore, recommended that, to the
maximum extent practical: (a) disturbed/loosened surficial soils be either removed or
properly recompacted, (b) irrigation systems be periodically inspected and maintained to
eliminate leaks and excessive irrigation, and (c) surface drains on and adjacent to slopes be
periodically maintained to preclude ponding or erosion. It should be noted that although the
incorporation of the above recommendations should reduce the potential for surficial slope
instability, it will not eliminate the possibility, and, therefore, it may be necessary to rebuild
or repair a portion of the project's slopes in the future.
6.10 Site Drainage and Moisture Protection
6.10.1 Adequate site drainage is critical to reduce the potential for differential soil movement,
erosion and subsurface seepage. Under nocircumstances should water be allowed to pond
adjacent to footings. The site should be graded and maintained such that surface drainage is
directed away from structures in accordance with 2016 CBC 1804.4 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 runoff away from the proposed structure.
6.10.2 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.
S
Project No. 06442-32-32 - 15- November 1, 2019
6.11 Grading and Foundation Plan Review
6.11.1 Geocon Incorporated should review the grading and foundation plans for the project prior to
final design submittal to evaluate whether additional analyses and/or. recommendations are
required.
Project No. 06442-32-32 -16- November 1, 2019
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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
NOT INTENDED FOR CLIENTS USE OR RELIANCE AND SHALL NOT BE REPRODUCED BY CLIENT. CLIENT
SHALL INDEMNIFY, DEFEND AND HOLD HARMLESS GEOCON FROM ANY LIABILITY INCURRED AS A RESULT
OF SUCH USE OR RELIANCE BY CLIENT. NO SCALE
VICINITY MAP
GEOCON
INCORPORATED (low)
GEOTECHNICAL U ENVIRONMENTAL U MATERIALS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
RM / AML DSK/GTYPD
CARLSBAD OAKS NORTH BUSINESS PARK
LOT 2
CARLSBAD, CALIFORNIA
I DATE 10-31 -2019 I PROJECT NO. 06442 - 32 - 32 1 FIG. 1
Plotted 11101/20199 48AM I By.RUBEN ACUILAR I File I 000Uon:Y:\PROJECTS\06442.32.32 (Lot 2)\DETAILS\06442-32-32 Vic Mop.dwg
APPENDIX
APPENDIX A
LABORATORY TEST RESULTS
Laboratory tests were performed in accordance with generally accepted test methods of the American
Society for Testing and Materials (ASTM) or other suggested procedures. Selected soil samples were
tested for their expansion potential and water soluble sulfate content. The results of our laboratory tests
are summarized on Table A-I.
TABLE A-I
SUMMARY OF FINISH GRADE LABORATORY EXPANSION INDEX, RESISTANCE
VALUE (R-VALUE), AND WATER-SOLUBLE SULFATE TEST RESULTS
Sample at I Expansion I I CBC I Sulfate I Lot No. Finish Grade I Index I R- Value i I Classificatiàn I Exposure I
2 P-2 25 20 Low Severe (S2) I
Project No. 06442-32-32 November 1, 2019
APPENDIX
APPENDIX B
STORM WATER MANAGEMENT
FOR
CARLSBAD OAKS NORTH BUSINESS PARK - LOT 2
CARLSBAD, CALIFORNIA S
PROJECT NO. 06442-32-32
STORM WATER MANAGEMENT INVESTIGATION
We understand storm water management devices are being proposed in accordance with the City of
Carlsbad Storm Water Standards. If not properly constructed, 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 effect on seepage transmission and the potential adverse impacts that may occur if the storm
water management features are not properly designed and constructed. We have not performed a
hydrogeological study at the site. If infiltration of storm water runoff occurs, downstream properties
may be subjected to seeps, springs, slope instability, raised groundwater, movement of foundations
and slabs, or other undesirable impacts as a result of water infiltration.
Hydrologic Soil Group
The United States Department of Agriculture (USDA), Natural Resources Conservation Services,
possesses general information regarding the existing soil conditions for areas within the United States.
The USDA website also provides the Hydrologic Soil Group. Table B-I presents the descriptions of
the hydrologic soil groups. If a soil is assigned to a dual hydrologic group (AID, B/D, or CID), the first
letter is for drained areas and the second is for undrained areas.
TABLE B-I
HYDROLOGIC SOIL GROUP DEFINITIONS
Soil Group Soil Group Definition
Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist
A mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a
high rate of water transmission.
Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of
B moderately deep or deep, moderately well drained or well drained soils that have moderately,
fine texture to moderately coarse texture. These soils have a moderate rate of water
transmission.
Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having
C a layer that impedes the downward movement of water or soils of moderately fine texture or
fine texture. These soils have a slow rate of water transmission.
Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These
D consist chiefly of clays that have a high shrink-swell potential, soils that have a high water
table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow
over nearly impervious material. These soils have a very slow rate of water transmission.
The subject sheet-graded pad is underlain by compacted fill placed above the Santiago Formation and
the Point Loma Formation. After completion of the proposed grading operations, the property would
consist of compacted fill over Santiago Formation and Pont Loma Formation. The compacted fill and
formational. materials should be classified as Soil Group D. In addition, the USDA website also
Project No. 06442-32-32 - B-I - November 1, 2019
provides an estimated saturated hydraulic conductivity for the existing soil. Table B-2 presents the
information from the USDA website. The Hydrologic Soil Group Map presents output from the
USDA website showing the limits of the soil units. The USDA information is presented herein.
TABLE B-2
USDA WEB SOIL SURVEY - HYDROLOGIC SOIL GROUP
Map Unit Approximate Hydrologic kSAT of Most
Map Unit Name Symbol Percentage Soil Group p Limiting Layer
of Property (Inches/ Hour)
Huerhuero loam HrD 100 D 0.00-0.06
In-Situ Testing
We performed three Soil Moisture, Inc. Aardvark Permeameter tests at the locations shown on the
attached Geologic Map, Figure 2. Test P-I was located in the Santiago Formation. Test P-2 was
located in the compacted fill near the existing temporary basin. Test P-3 was hand augered until
practical refusal was encountered on the Point Loma Formation contact. The test borings were 4
inches in diameter. The results of the tests provide parameters regarding the saturated hydraulic
conductivity and infiltration characteristics of on-site soil and geologic units. Table B-3 presents the
results of the field saturated hydraulic conductivity/infiltration rates obtained from the Aardvark
Permeameter tests. The data sheets are presented herein. We applied a feasibility factor of safety of 2
to the test results. Soil infiltration rates from in-situ tests can vary significantly from one location to
another due to the non-homogeneous characteristics inherent to most soil.
TABLE B-3
FIELD PERMEAMETER INFILTRATION TEST RESULTS
Test Depth Field-Saturated Field
Test No. Geologic Unit (feet, below grade) Hydraulic Conductivity, Infiltration Rate
k,,t (inch/hour) (inch/hour)
P-I Isa 2.9 0.045 0.023
P-2 Quc 1.75 0.069 0.035
P-3 Kp 1.25 0.001 0.0005
STORM WATER MANAGEMENT CONCLUSIONS
The Geologic Map, Figure 2, presents the existing property, proposed development, and the locations
of the in-situ infiltration test locations.
Project No. 06442-32-32 - B-2 - November 1, 2019
Soil Types
Compacted Fill - Compacted fill exists across the property. The proposed storm water BMP's will be
founded in compacted fill placed above very dense formational materials. The compacted fill is
comprised of sandy/clayey silt, silty sand and clayey sand. The fill has been compacted to a dry
density of at least 90 percent of the laboratory maximum dry density. In our experience, compacted fill
does not possess infiltration rates appropriate for infiltration BMP's, as demonstrated by the in-situ
testing. Hazards that occur as a result of fill soil saturation include a potential for hydro-consolidation
of the granular fill soils and/or swelling of the expansive soils, long-term fill settlement, differential
fill settlement, and lateral movement associated with saturated fill relaxation. The potential for lateral
water migration to adversely impact existing or proposed structures, foundations, utilities, and
roadways, is high. Therefore, full and partial infiltration should be considered infeasible.
Section D.4.2 of the 2016 Storm Water Standards (SWS) provides a discussion regarding fill materials
used for infiltration. The SWS states:
For engineered fills, infiltration rates may still be quite uncertain due to layering and
heterogeneities introduced as part of construction that cannot be precisely controlled. Due to
these uncertainties, full and partial infiltration should be considered geotechnically infeasible
and liners and subdrains should be used in areas where infiltration BMP's are founded in
compacted fill.
Where possible, infiltration BMPs on fill material should be designed such that their
infiltrating surface extends into native soils. The underlying formation below the compacted
fill is expected between 3 to 16 feet below proposed finish grades after remedial grading is
performed. Full and partial infiltration should be considered geotechnically infeasible within
the compacted fill and liners and subdrains should be used.
. Because of the uncertainty of fill parameters as well as potential compaction of the native
soils, an infiltration BMP may not be feasible. Therefore, full and partial infiltration should be
considered geótechnically infeasible and liners and subdrains should be used in the fill areas.
If the source offill material is defined and this material is known to be of a granular nature
and that the native soils below are permeable and will not be highly compacted, infiltration
through compacted fill materials may still be feasible. In this case, a project phasing
approach could be used including the following general steps, (1) collect samples from areas
expected to be used for fill, (2) remold samples to approximately the proposed degree of
compaction and measure the saturated hydraulic conductivity of remolded samples using
laboratory methods, (3) if infiltration rates appear adequate for infiltration, then apply an
appropriate factor of safety and use the initial rates for preliminary design, (4) following
placement of fill, conduct in-situ testing to refine design infiltration rates and adjust the
design as needed. However, based on the discussion above, it is our opinion that infiltrating
into compacted fill should be considered geotechnically infeasible and liners and subdrains
should be used.
Project No. 06442-32-32 - B-3 - November 1, 2019
Infiltration Rates
The results of the unfactored infiltration rates (i.e. field saturated hydraulic conductivity) for Tests P-I,
P-2, and P-3 were 0.04 inches per hour (iph), 0.07 iph and 0.001 iph, respectively. After applying a
feasibility factor of safety of 2.0, the infiltration rates obtained for P-i, P-2 and P-3 are 0.02 iph, 0.035
iph and 0.0005 iph, respectively. The infiltration test results show the on-site soil permeability is
variable across the site. A single design rate for an area could not be accurate based on the variability.
Therefore, based on the results of the field infiltration tests, anticipated grading, and our experience,
full and partial infiltration should be considered infeasible. The results of the permeability testing are
presented below.
Groundwater Elevations
Groundwater is expected to be encountered at depths greater than 100 feet below the site, therefore
groundwater is not expected to be a factor. Groundwater mounding is caused when infiltration is
allowed and the lateral hydraulic conductivity is relatively low causing an increase in the groundwater
table. Groundwater mounding is not likely.
Soil or Groundwater Contamination
Based on review of the Geotracker website, no active cleanup sites exist on or adjacent to the subject
site. In addition, we are not aware of any contaminated soils or shallow groundwater on the site that
would preclude storm water infiltration. An environmental assessment was not part of our scope of
work.
Slopes
Existing slopes exist on the perimeter of the property. A stability fill was constructed along the lower
portions of the southerly ascending slope to reduce the potential for daylight water seepage and slope
instability. Infiltration of storm water adjacent to cut or fill slopes should be avoided. Fill slopes will
exhibit instability if water is allowed to saturate the compacted fill. Cut slopes may exhibit daylight
seepage.
Storm Water Management Devices
Based on the discussion above, all three infiltration tests did not meet the minimum feasibility criteria
for full or partial infiltration. To limit the adverse impacts of storm water infiltration, i.e. lateral water
migration, daylight water seepage, etc., the design should include liners and subdrains. The
impermeable liners should consist of a high-density polyethylene, HDPE, with a thickness of about
30 mil or equivalent Polyvinyl Chloride, PVC. The liner should surround the bottom and sides of the
infiltrating surface and should extend slightly above the high water elevation. The subdrain should be
perforated, installed near the base of the excavation, be at least 4-inches in diameter and consist of
Project No. 06442-32-32 - B-4 - November I, 2019
Schedule 40 PVC pipe. The final segment of the subdrain outside the limits of the storm water BMP
should consist of solid pipe and connected to a proper outlet. Any penetration of the liner should be
properly waterproofed. The devices should also be installed in accordance with the manufacturer's
recommendations.
Storm Water Standard Worksheets
The Storm Water Standard manual stipulates the geotechnical engineer complete the Categorization of
Infiltration Feasibility Condition (Worksheet C.4-1 or Form 1-8) worksheet information help
evaluate the potential for infiltration on the property. A completed Form 1-8 is presented below.
The regional storm water standards also have a worksheet (Worksheet D.51 or Form 1-9) that helps
the project civil engineer estimate the factor of safety based on several factors. Table B-4 describes the
suitability assessment input parameters related to the geotechnical engineering aspects for the factor of
safety determination.
TABLE B-4
SUITABILITY ASSESSMENT RELATED CONSIDERATIONS FOR INFILTRATION FACILITY
SAFETY FACTORS
Consideration High Medium Low
Concern —3 Points Concern - 2 Points Concern - I Point
Use of soil survey maps Use of well permeameter U
or simple texture analysis or borehole methods
with accompanying Direct measurement with
to estimate short-term continuous boring log, localized (i.e. small-
infiltration rates. Use of Direct measurement of scale) infiltration testing
Assessment Methods well permeameter 0!' infiltration area with methods at relatively
borehole methods without lOcalized infiltration high resolution or use of
accompanying continuous measurement methods extensive test pit
boring log. Relatively (e.g., infiltrometer). infiltration measurement
sparse testing with direct Moderate spatial
methods.
infiltration methods resolution
Predominant Soil Texture Silty and clayey soils Loamy soils Granular to slightly
with significant fines loamy soils
Highly variable soils Soil boring/test pits Soil boring/test pits
Site Soil Variability indicated from site
assessment or unknown indicate moderately indicate relatively
variability homogenous soils homogenous soils
Depth to Groundwater/ . <5 feet below 5-15 feet below >15 feet below
Impervious Layer facility bottom facility bottom facility bottom
Based on our geotechnical investigation and the previous table, Table B-5 presents the estimated
factor values for the evaluation of the factor of safety. This table only presents the suitability
Project No. 06442-32-32 - B-S - November 1, 2019
assessment safety factor (Part A) of the worksheet. The project civil engineer should evaluate the
safety factor for design (Part B) and use the combined safety factor for the design infiltration rate.
TABLE B-5
FACTOR OF SAFETY WORKSHEET DESIGN VALUES - PART A1
Suitability Assessment Factor Category Assigned
Weight (w)
Factor
Value (v)
. Product
(p = w x v)
Assessment Methods 0.25 3 0.75
Predominant Soil Texture 0.25 3 0.75
Site Soil Variability 0.25 3 0.75
Depth to Groundwater/ Impervious Layer 0.25 1 0.25
Suitability Assessment Safety Factor, SA = Ep 2.5
The, project civil engineer should complete Worksheet D.5-1 or. Form 1-9 using the data provided above.
Additional information is required to evaluate the design factor of safety.
Project No. 06442-32-32 - B-6 - November 1, 2019
USDA United States
Department of
Agriculture
NRCS
Natural
Resources
Conservation
Service
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
San Diego County
Area, California
Carlsbad Oaks North - Lot 2
October 1, 2019
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/
portal/nrcs/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?
cid=nrcs142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons.with disabilities who require
2
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice
and TOO). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity
provider and employer.
3
Contents
Preface.................................................... ................................................................ 2
How Soil Surveys Are Made ............................................................ ...................... 5
SoilMap .............................................................................................. ..................... 8
SoilMap................................................................................................................9
Legend........................................................................................ . ........................ 10
MapUnit Legend................................................................................................11
MapUnit Descriptions.........................................................................................11
San Diego County Area, California ............................................. . ................... 13.
HrD—Huerhuero loam, 9 to 15 percent slopes...........................................13
References .......................................................
/
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and-has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRA5). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil-vegetation-landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5
Custom Soil Resource Report
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil-landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil-landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field-observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
[;j
Custom Soil Resource Report
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
7
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
II
8
37' 7 ITN
Custom Soil Resource Report
Soil Map
475373 475660 475700 4757413 475787 475870 47540 470 475940 47988
All
(
37' 81rN
33" 88' N 37' 88 N
:
I
I I 11h
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, 4,i
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Map Scale: 1:1,91Oif printed onA landscape (11"x8.5")sheet.
-Meters
N o 25 50 ico 159
Feet
J 0 59 1(X) 2(X)
Map projection: Web Mercator Corner ordinates: WG584 Edge tks: UTM Zone uN WGS84
Custom Soil Resource Report
Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOl Percent of AOl
HrO Huerhuero loam, 9 to 15
percent slopes
8.3 100.0%
Totals for Area of Interest 8.3 100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey. area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was imractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
11
Custom Soil Resource Report
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example:
12
Custom Soil Resource Report
San Diego County Area, California
HrD—Huerhuero loam, 9 to 15 percent slopes
Map Unit Setting
National map unit symbol: hbcp
Elevation: 1,100 feet
Mean annual precipitation: 12 to 20 inches
Mean annual air temperature: 57 degrees F
Frost-free period: 260 days
Farmland classification: Not prime farmland
Map Unit Composition
Huerhuero and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Huerhuero
Setting
Landform: Marine terraces
Down-slope shape: Concave
Across-slope shape: Concave
Parent material: Calcareous alluvium derived from sedimentary rock
Typical profile
HI - 0. to 12 inches: loam
H2 - 12 to 55 inches: clay loam, clay
H2 - 12 to 55 inches: stratified sand to sandy loam
H3 - 55 to 72 inches:
Properties and qualities
Slope: 9 to 15 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Moderately well drained
Runoff class: Very high
Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately
low (0.00 to 0.06 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Salinity, maximum in profile: Nonsaline to very slightly saline (0.0 to 2.0
mmhos/cm)
Sodium adsorption ratio, maximum in profile: 25.0
Available water storage in profile: Moderate (about 6.6 inches)
Interpretive groups
Land capability classification (irrigated): 4e
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: D
Ecological site: CLAYPAN (1975) (RO19XDO6ICA)
Hydric soil rating: No
13
Custom Soil Resource Report
Minor Components
Las flores
Percent of map unit: 10 percent
Hydric soil rating: No
Oliventain
Percent of map unit: 3 percent
Hydric soil rating: No
Unnamed
Percent of map unit: 2 percent
Hydric soil rating: No
14
References
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of sampling
and testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-00.
Cowardin, LM., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife
Service FWS/OBS-791'31.
Federal Register. July 13, 1994. Changes in hydnc soils of the United States.
Federal Register. September 18, 2002. Hydric soils of the United States.
Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric
soils in the United States.
National Research Council. 1995. Wetlands: Characteristics and boundaries.
Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.
U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.govlwps/portall
nrcs/detail/nationallsoils/?cid=nrcs142p2_054262
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil.classification for
making and interpreting soil surveys. 2nd edition. Natural Resources Conservation
Service, U.S. Department of Agriculture Handbook 436. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrc5142p2 053577
Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http:/I
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580
Tuner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section. I
United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of
Engineers wetlands delineation manual. Waterways Experiment Station Technical
Report Y-87-1.
United States Department of Agriculture, Natural Resources Conservation Service.
National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
home/?cid=nrcs142p2_053374
United States Department of Agriculture, Natural Resources Conservation Service.
National range and pasture handbook.http://www.nrcs.usda.gov/wps/portal/nrcs/
detail/national/landuselrangepasture/?cid=ste1prdb1043084
15
Custom Soil Resource Report
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430-VI. http:llwww.nrcs.usda.govlwpslportall
nrcs/detail/soils/scientists/?cid=nrcs142p2_054242.
United States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States,
the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook
296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?
cid=nrcs142p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210. http://
www.nrcs.usda.gov/lntemetlFSE_DOCUMENTS/nrcs142p2052290.pdf
16
APPENDIX
RECOMMENDED GRADING SPECIFICATIONS
1. GENERAL
Ii These Recommended Grading Specifications shall be used in conjunction with the
Geotechnical Report for the project prepared by Geocon. 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 Consultant 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, and/or 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.
fr_
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 consulting firm responsible for preparation of the grading plans, surveying and verifying
as-graded topography.
2.4 Consultant shall refer to the soil engineering and engineering geology consulting firm
retained to provide geotechnical services for the project.
GI rev. 07/2015
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'
.
he 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 3h inch in maximum dimension. The quantity of fines shall be
less than approximately 20 percent of the rock fill quantity.
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 Regulations, Title 22, Division 4, Chapter 30, Articles 9
GI rev. 07/2015
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 Consultant. 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 I V2 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.
4.2 Asphalt pavement material removed during clearing operations should be properly
disposed at an approved off-site facility or in an acceptable area of the project evaluated by
Geocon and the property owner. 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.
GI rev. 07/2015
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 (horizontal:vertical), or
where recommended by the Consultant, the original ground should be benched in
accordance with the following illustration.
TYPICAL BENCHING DETAIL
Finish Grade A ...—Original Ground
2
Finish Slope Surface
Remove All
Unsuitable Material
As Recommended By
ue ToIThat
SloConsultant ghingOrSliding
Does Not Occur Varies
"B"
See Note 1 - See Note 2
No Scale
DETAIL NOTES: (I) 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.
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.
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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.
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
Consultant 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.
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. Compaction 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.
GI rev. 07/2015
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.
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 flooding. 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 Consultant.
GI rev. 07/2015
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 site 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
required compaction or deflection 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, may be performed in both
the compacted soil 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
01 rev. 07/2015
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 Consultant 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 Consultant 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 filter material below the rock
should be determined' by the Consultant prior to commencing grading. The
gradation of the graded filter material will be determined at the time the rock fill is
being excavated. Materials typical of the rock fill should be submitted to the
Consultant in a timely manner, to allow design of the graded filter prior, to the
commencement of rock fill placement.
6.3.7 Rock fill placement should be continuously observed during placement by the
Consultant. .
7. SUBDRAINS
7.1 The geologic units on the site may have permeability characteristics and/or fracture
systems that could be susceptible under certain conditions to seepage. The use of canyon
subdrains may be necessary to mitigate the potential for adverse impacts associated with
seepage conditions. Canyon subdrains with lengths in excess of 500 feet or extensions of
existing offsite subdrains should use 8-inch-diameter pipes. Canyon subdrains less than 500
feet in length should use 6-inch-diameter pipes.
GI rev. 07/2015
8. OBSERVATION AND TESTING
8.1 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 density
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.
8.2 The Consultant 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.
8.3 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 pits 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.
8.4 A settlement monitoring program designed by the Consultant may be conducted in areas of
rock fill placement. The specific design of the monitoring 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.
8.5 We should observe the placement of subdrains, to check that the drainage devices have
been placed and constructed in substantial conformance with project specifications.
8.6 Testing procedures shall conform to the following Standards as appropriate:
8.6.1 Soil and Soil-Rock Fills:
8.6.1.1 Field Density Test, ASTM D 1556, Density of Soil In-Place By the
Sand-Cone Method.
GI rev. 07/2015
8.6.1.2 Field Density Test, Nuclear Method, ASTM D 6938, Density of Soil and
Soil-Aggregate In-Place by Nuclear Methods (Shallow Depth).
8.6.1.3 Laboratory Compaction Test, ASTM D 1557, Moisture-Density
Relations of Soils and Soil-Aggregate Mixtures Using 10-Pound
Hammer and 18-Inch Drop.
8.6.1.4. Expansion Index Test, ASTM.D 4829, Expansion Index Test.
9. PROTECTION OF WORK
9.1 During construction, the Contractor shall properly grade all excavated surfaces to provide
positive 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 site. 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 additional fill or structures.
9.2 After completion of grading as observed and tested by the Consultant, no further
excavation or filling shall be conducted except in conjunction with the services of the
Consultant.
10. CERTIFICATIONS AND FINAL REPORTS
10.1 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.
10.2 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. 07/2015
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WITH CONCRETE sa ........ SANTIAGO FORMATION FORMATION (Dotted Where Buried)
Kp .... POINT LOMA FORMATION (Dotted Where Buried)
. .........APPROX. LOCATION OF GEOLOGIC CONTACT
(Dotted Where Buried; Queried Where Uncertain)
E11 ..... ...APPROX. ELEVATION AT BASE OF FILL
..........APPROX. LOCATION OF SUBDRAIN
APPROX. ELEVATION OF SUBDRAIN GEOLOGIC MAP
APPROX. LOCATION OF INACTIVE FAULT CARLSBAD OAKS NORTH BUSINESS Pi
U .... Upthrown Side (Apparent) LOT 2 D .... Downthrown Side (Apparent) CARLSBAD, CALIFORNIA
((I........ APPROX. LOCATION OF INFILTRATION TEST
A A GE '
SCALE 1" = 60'
I APPROX. LOCATION OF GEOLOGIC CROSS SECTION '' ' ''
INCORPORATED PROJECT NO. 064
APPROX. LIMITS OF BUTTRESS FILL GEOTECHNICALa ENVIRONMENTAL a MATERIALS
1-1
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