HomeMy WebLinkAboutCUP 2017-0008; OAKMONT OF CARLSBAD; UPDATE GEOTECHNICAL REPORT; 2019-05-20RECORD COPY
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Initial Date
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UPDATE
GEOTECHNICAL REPORT
OAKMONT OF CARLSBAD
CARLSBAD OAKS NORTH BUSINESS
PARK-LOT I
CUP 2017-0008, GR2019-0013, DWG 5174A
CARLSBAD, CALIFORNIA
ri
PREPARED FOR
OAKMÔNT SENIOR LIVING
WINDSOR CALIFORNIA
E. RECEIVE" .flff No. RCE63173)
FEB 18 2020 EXP. 9/30/20 J
LAND DEVELOPMEN CFC '
ENGINEERING
MAY 20, 2019
PROJECT NO. 06442-32-29
GEOCON
INCORPORATED
GEOTECHNICAL • ENVIRONMENTAL MATERIALS0
Project No. 06442-32-29
May 20, 2019
Oakmont Senior Living
9240 Old Redwood Highway, Suite 200
Windsor, California 95492
Attention: Mr. Gregg Wanke
Subject: UPDATE GEOTECHNICAL REPORT
OAKMONT OF CARLSBAD
CARLSBAD OAKS NORTH BUSINESS PARK - LOT 1
CUP 2017-0008, GR2019-0013, DWG 5174A
CARLSBAD, CALIFORNIA
Dear Mr. Wanke:
In accordance with your authorization, we have prepared an update geotechnical report for the
proposed development of Oakmont of Carlsbad. 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 three-
story luxury assisted-living facility, a two-story memory care building and a one-story models building
with associated roadways, 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 EU
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TEM:DBE:kcd li No. RcE 63
(2) Addressee
CIV
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David B. Evans
CEG 1860
DAVID B.
EVANS
NO. 1860
CERTIFIED
ENGINEERING
GEOLOGIST
6960 Flanders Drive U Son Diego, California 92121.2974 U Telephone 858.558.6900 0 Fax 858.558.6159
TABLE OF CONTENTS
PURPOSE AND SCOPE.................................................................................................................
SITE AND PROJECT DESCRIPTION ........................................................................................... 1
SOILAND GEOLOGIC CONDITIONS ........................................................................................2
3.1 Compacted Fill ......................................................................................................................2
3.2 Point Loma Formation...........................................................................................................2
GROUNDWATER .......................................................................................................................... 2
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
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 ..................................................................................................................................12
6.7 Foundation and Concrete Slab-On-Grade Recommendations.............................................12
6.8 Retaining Walls and Lateral Loads .....................................................................................15
6.9 Preliminary Pavement Recommendations - Flexible and Rigid.........................................17
6.10 Storm Water Management...................................................................................................19
6.11 Slope Maintenance ..............................................................................................................20
6.12 Site Drainage and Moisture Protection................................................................................21
6.13 Foundation Plan Review......................................................................................................21
HydrologicSoil Group.....................................................................................................................
In-Situ Testing .................................................................................................................................2
SoilTypes .......................................................................................... . ............................................. 3
InfiltrationRates..............................................................................................................................4
GroundwaterElevations...................................................................................................................4
Soil or Groundwater Contamination................................................................................................4
Slopes................................................................................................................................................ 4
Storm Water Management Devices .................................................................................................4
Storm Water Standard Worksheets..................................................................................................5
LIMITATIONS AND UNIFORMITY OF CONDITIONS
MAPS AND ILLUSTRATIONS
Figure 1, Vicinity Map
Figure 2, Geologic Map (map pocket)
Figure 3, Wall/Column Footing Dimension Detail
Figure 4, Typical Retaining Wall Drainage Detail
TABLE OF CONTENTS (CONCLUDED)
APPENDIX A
RESULTS OF LABORATORY TESTING
Table A-I, Summary of Laboratory Expansion Index 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 the proposed development of the
Carlsbad Oaks North Business Park Lot 1 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 investigation 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 following plans and
Geocon Incorporated reports associated with the site.
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.
Addendum to Final Report of Testing and Observation Services During Site Grading,
Carlsbad Oaks North Business Park - Phase 1, Lot 1, Carlsbad, California, prepared by
Geocon Incorporated, dated October 30, 2008.
Transmittal of Geotechnical Information, Carlsbad Oaks North - Lot 1, Carlsbad, California,
prepared by Geocon Incorporated, dated September 25, 2017 (Project No. 06442-32-29).
Update Geotechnical Correspondence, Carlsbad Oaks North Lot 1, Carlsbad, California,
prepared by Geocon Incorporated, dated June 28, 2017 (Project No. 06442-32-29).
Preliminary Grading and Drainage Plan, Oakmont of Carlsbad, Lot 1 of Tract No. 14926,
Carlsbad, California, prepared by Alliance Land Planning and Engineering, Inc., Sheets 1
through 9 of 9, undated.
The descriptions of the soil and geologic conditions and proposed development described herein is
based on review of the above referenced reports and plans, and observations made during mass
grading operations for the overall Carlsbad Oaks Business Park development.
2. SITE AND PROJECT DESCRIPTION
Lot I is a sheet-graded pad located west of the intersection of Faraday Avenue and El Fuerte Street, in
the City of Carlsbad, California (see Vicinity Map, Figure 1).
Lot I consists of an easterly sloping sheet graded pad that was created in 2006 during the overall mass
grading of Carlsbad Oaks North Phase I (reference No. I). The lot was originally left low and
subsequently completed in 2008 (reference No. 2). The as-graded condition consists of compacted fill
underlain by the Point Loma Formation. The center portion of the pad was undercut to eliminate cut-
fill transitions that resulted from the mass grading. Fill thicknesses across the pad range from
Project No. 06442-32-29 - I - May 20, 2019
approximately 3 to 20 feet. The surficial soils have a "low" to "medium" expansion potential and a
"moderate" to "severe" sulfate exposure rating.
The referenced plan indicates that development will consist of fine grading the site to support a three-
story independent living facility, a two-story memory care building and a one-story models building.
A pool, parking areas and associated infrastructure is also proposed. The independent living and
memory care buildings are shown with one level of underground parking. Cuts and fills on the order of
13 and 7 feet, respectively, will be necessary to achieve the final building pad configurations.
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.
3. SOIL AND GEOLOGIC CONDITIONS
Compacted fill and the Point Loma Formation underlies the site. Descriptions of these units are
presented below. The as-graded site geology is presented on Figure 2.
3.1 Compacted Fill
Compacted fill materials 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. The approximate base elevation of the compacted fill across the site is
shown on the Geologic Map, Figure 2.
3.2 Point Loma Formation
Cretaceous-age Point Loma Formation underlies the compacted fill and is exposed in a cut slope
adjacent to Faraday Avenue. 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 footings and
shallow underground utilities. Excavations for underground parking are expected to encounter this
formation.
4. GROUNDWATER
Groundwater was not observed during the grading operations. Groundwater is not anticipated to
impact proposed project development, however, perched water conditions may develop following
Project No. 06442-32-29 -2- May 20, 2019
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 toa 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).
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 0.31g, 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. 06442-32-29 -3- May 20, 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 0.27 0.24 0.31
Rose Canyon 8 6.9 0.22 0.23 0.24
Elsinore 20 7.85 0.19 0.13 0.17
Coronado Bank 23 7.4 0.14 0.10 0.12
Palos Verdes Connected 23 7.7 0.16 0.11 0.14
Earthquake Valley 39 6.8 0.07 0.05 0.04
Palos Verdes. 39 7.3 0.09 0.07 0.07
San Joaquin Hills 39 7.1 0.08 0.08 0.07.
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.
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% in a 50 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
Project No. 06442-32-29 -4- May 20, 2019
While listing peak accelerations is useful for comparison of potential effects of fault activity in a
region, other considerations are important in seismic design, including the frequency and duration of
motion and the soil conditions underlying the site. Seismic design of the 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. The risk associated with landslide hazard is very low.
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 250 feet above Mean Sea Level (MSL).
Project No. 06442-32-29 - 5 - May 20, 2019
S. CONCLUSIONS AND RECOMMENDATIONS
6.1 General
6.1.1 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 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 "medium"
expansion potential, and "moderate" to "severe" water soluble sulfate content. The
compacted fill and Point Loma Formation are considered suitable to support the proposed
structures.
6.1.3 The proposed buildings can be supported on conventional continuous and isolated spread
shallow foundations founded entirely on formational materials or compacted fill.
6.1.4 Cut-fill transitions will occur beneath several of the proposed structures. The
cut/formational portions of these areas will require undercutting. Once the grading plan is
finalized, these areas should be evaluated and remedial grading recommendations should be
provided at that time.
6.1.5 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.
6.1.6 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 have an Expansion Index ranging from 50 to 74 and
are classified as having a "low" to "medium" expansion potential as defined by 2016
California Building Code (CBC) Section 1803.5.3. A summary of the laboratory expansion
Project No. 06442-32-29 -6- May 20, 2019
index test results performed during sheet-grading are presented in Appendix A. Table 6.2
presents soil classifications based on the expansion index.
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 to
excavate using conventional heavy-duty grading equipment. Excavations for underground
parking and underground improvements that extend through the compacted fill and into the
Point Loma Formation 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.
6.3 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 "Moderate" and "Si" to "Severe" and "S2" sulfate exposure to concrete structures
as defined by 2016 CBC Section 1904 and ACI 318-14 Chapter 19. Table 6.3 presents a
summary of concrete requirements set forth by 2016 CBC Section 1904 and AC! 318.
Project No. 06442-32-29 -7- May 20, 2019
TABLE 6.3
REQUIREMENTS FOR CONCRETE EXPOSED
TO SULFATE-CONTAINING SOLUTIONS
Water-Soluble Cement
Maximum Minimum
Sulfate Exposure Sulfate (SO4) Water to Type Cement Compressive
Severity Class Percent (ASTM C 150) Ratio Strength
by Weight by Weight' (psi)
Not Applicable SO SO4<0.10 No Type
Restriction
n/a 2,500
Moderate SI 0.I0SO4<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+Pozzolan
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 (OSHPD) 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 Point
Loma Formation 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. 06442-32-29 -8- May 20, 2019
TABLE 6.4.1
2016 CBC SEISMIC DESIGN PARAMETERS
Parameter Value 2016 CBC Reference
Site Class C Section 1613.3.2
MCER Ground Motion Spectral 1.045g 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(l)
Site Coefficient, Fv 1.395 Table 1613.3.3(2)
Site Class Modified MCER Spectral 1.045g Section 1613.3.3 (Eqn 16-37) Response Acceleration (short), SMS
Site Class Modified MCER Spectral 0.565g Section 16 13.3.3 (Eqn 16-38) Response Acceleration (1 sec), S41
5% Damped Design Spectral 0.696g Section 16 13.3.4 (Eqn 16-39)
Response Acceleration (short), SDS
5% Damped Design Spectral 0.377g Section 1613.3.4 (Eqn 16-40) Response Acceleration (1 sec), So1
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 (MCEG).
TABLE 6.4.2
2016 CBC SITE ACCELERATION PARAMETERS
Parameter Site Class C ASCE 7-10 Reference
Mapped MCEG Peak Ground Acceleration, 0.399g Figure 22-7
PGA
Site Coefficient, FPGA 1.001 Table 11.8-1
Site Class Modified MCEG 0.399g Section 11.8.3 (Eqn 11.8-1) Peak Ground Acceleration, PGAM
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. 06442-32-29 -9- May 20, 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. 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
granitic rock. The wet soils will require drying and/or mixing with drier soils to facilitate
proper compaction.
6.5.7 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,
Project No. 06442-32-29 _10- May 20, 2019
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.
6.5.8 Proposed grading will result in a cut-fill transitions within the footprints of several of the
proposed buildings. Foundation elements bearing on both compacted fill and bedrock may
result in potentially unacceptable differential settlements. An evaluation of this condition
should be performed to determine which areas should be undercut to mitigate the cut-fill
conditions.
6.5.9 To reduce the potential for differential settlement, the bedrock portion of the cut-fill
transition should be over-excavated (undercut) a minimum of 3 feet below finish pad grade
or at least two feet below the lowest foundation element, whichever is deeper, and replaced
with compacted low to medium expansive (Expansion Index [El] 90) soil fill
predominately consisting of 6-inch-minus rock. The undercutting will also facilitate
excavation of proposed foundation system and shallow utilities beneath the building. The
undercut should extend at least five feet horizontally outside the limits of the building
footprint area and isolated spread footings located outside the building limits.
Overexcavations should be cut at a gradient toward the deepest fill area to provide drainage
for moisture migration along the contact between the bedrock and compacted fill.
6.5.10 For areas to receive fill and undercut areas, rock fragments greater than 6 inches in
maximum dimension should not be placed within five feet of finish grade in the building
pad area and three feet of subgrade in driveways/parking areas. Rock fragments greater than
12 inches in maximum dimension should be placed at least 10 feet below finish grade and
least one foot below deepest planned utility.
6.5.11 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.
6.5.12 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
Project No. 06442-32-29 - II - , May 20, 2019
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 Slope stability analyses were previously performed on the 2:1 slopes on the property for the
overall Carlsbad Oaks North Business Park development (see the referenced geotechnical
reports). The deep-seated and surficial slope stability analyses where performed using the
simplified Janbu analysis utilizing average drained direct shear strength parameters based on
laboratory tests performed during our investigation. The results of the analysis indicate that
cut and fill slopes have a factor-of-safety of at least 1.5 against deep seated and surficial
instability for the project slopes.
6.6.2 No new significant fill slopes are planned during the fine grading.
6.6.3 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.
6.7 Foundation and Concrete Slab-On-Grade Recommendations
6.7.1 The project is suitable for the use of continuous strip footings, isolated spread footings, or
appropriate combinations thereof, provided the preceding grading recommendations are
followed.
6.7.2 The following recommendations are for the planned structures and assume that the
foundation systems for the structures will bear on compacted fill exhibiting a "medium"
expansion potential. A typical footing dimension detail is presented on Figure 3.
6.7.3 Continuous footings should be at least 12 inches wide and should extend at least 18 inches
below lowest adjacent pad grade. Isolated spread footings should be at least two feet square
and extend a minimum of 18 inches below lowest adjacent pad grade.
6.7.4 Isolated footings, which are located beyond the perimeter of the buildings and support
structural elements connected to the building, should be connected to the building
foundation system with grade beams.
6.7.5 The project structural engineer should design the reinforcement for the footings. For
continuous footings, however, we recommend minimum reinforcement consisting of two
Project No. 06442-32-29 -12- May 20, 2019
No. 5 steel reinforcing bars, one placed near the top of the footing and one placed near the
bottom. The project structural engineer should design reinforcement of isolated spread
footings.
6.7.6 The recommended allowable bearing capacity for foundations designed as recommended
above is 2,500 pounds per square foot (psf) for foundations in properly compacted fill soil.
This soil bearing pressure may be increased by 300 psf and 500 psf for each additional foot
of foundation width and depth, respectively, up to a maximum allowable soil bearing of
4,000 psf.
6.7.7 The allowable bearing pressures recommended above are for dead plus live loads only and
may be increased by up to one-third when considering transient loads such as those due to
wind or seismic forces.
6.7.8 The estimated maximum total and differential settlement for the planned structures due to
foundation loads is 1 inch and 3h inch, respectively, over a span of 40 feet.
6.7.9 Building interior concrete slabs-on-grade should be at least five inches in thickness. Slab
reinforcement should consist of No. 3 steel reinforcing bars spaced 18 inches on center in
both directions placed at the middle of the slab. If the slabs will be subjected to heavy loads,
consideration, should be given to increasing the slab thickness and reinforcement. The
project structural engineer should design interior concrete slabs-on-grade that will be
subjected to heavy loading (i.e., fork lift, heavy storage areas). Subgrade soils supporting
heavy loaded slabs should be compacted to at least 95 percent relative compaction.
6.7.10 A vapor retarder should underlie slabs that may receive moisture-sensitive floor coverings
or may be used to store moisture-sensitive materials. The vapor retarder design should be
consistent with the guidelines presented in the American Concrete Institute's (AC!) Guide
for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials (AC! 302.2R-06). In
addition, the membrane should be installed in a manner that prevents puncture in accordance
with manufacturer's recommendations and ASTM requirements. The project architect or
developer should specify the, type of vapor retarder used based on the type of floor covering
that will be installed and if the structure will possess a humidity controlled environment.
6.7.11 The project foundation engineer, architect, and/or developer should determine the thickness
of bedding sand below the slab. Typically, 3 to 4 inches of sand bedding is used in the San
Diego County area. Geocon should be contacted to provide recommendations if the bedding
sand is thicker than 6 inches.
Project No. 06442-32-29 - 13- May 20, 2019
6.7.12 Exterior slabs not subject to vehicle loads should be at least 4 inches thick and reinforced
with 6x6-W2.91W2.9 (6x6-6/6) welded wire mesh or No. 3 reinforcing bars spaced at
24 inches on center in both directions to reduce the potential for cracking. The mesh should
be placed in the middle of the slab. Proper mesh positioning is critical to future performance
of the slabs. The contractor should take extra measures to provide proper mesh placement.
Prior to construction of slabs, the subgrade should be moisture conditioned to at least
optimum moisture content and compacted to a dry density of at least 90 percent of the
laboratory maximum dry density in accordance with ASTM 1557.
6.7.13 To control the location and spread of concrete shrinkage and/or expansion cracks, it is
recommended that crack-control joints be included in the design of concrete slabs. Crack-
control joint spacing should not exceed, in feet, twice the recommended slab thickness in
inches (e.g., 10 feet by 10 feet for a 5-inch-thick slab). Crack-control joints should be
created while the concrete is still fresh using a grooving tool or shortly thereafter using saw
cuts. The structural engineer should take criteria of the American Concrete Institute into
consideration when establishing crack-control spacing patterns.
6.7.14 The above foundation and slab-on-grade dimensions and minimum reinforcement
recommendations are based upon soil conditions only, and are not intended to be used in
lieu of those required for structural purposes. The project structural engineer should design
actual concrete reinforcement.
6.7.15 No special subgrade presaturation is deemed necessary prior to placement of concrete.
However, the slab and foundation subgrade should be moisture conditioned as necessary to
maintain a moist condition as would be expected in any concrete placement.
6.7.16 The recommendations of this report are intended to reduce the potential for cracking of slabs
due to expansive soil (if present), differential settlement of existing soil or soil with varying
thicknesses. However, even with the incorporation of the recommendations presented
herein, foundations, stucco walls, and slabs-on-grade placed on such conditions may still
exhibit some cracking due to soil movement and/or shrinkage. The occurrence of concrete
shrinkage cracks is independent of the supporting soil characteristics. Their occurrence may
be reduced and/or controlled by limiting the slump of the concrete, proper concrete
- placement and curing, and by the placement of crack control joints at periodic intervals, in
particular, where re-entrant slab corners occur.
6.7.17 A representative of Geocon Incorporated should observe the foundation excavations prior to
the placement of reinforcing steel or concrete to check that the exposed soil conditions are
consistent with those anticipated. If unanticipated soil conditions are encountered,
foundation modifications may be required.
Project No. 06442-32-29 -14- May 20, 2019
6.7.18 Geocon Incorporated should be consulted to provide additional design parameters as
required by the structural engineer.
6.8 Retaining Walls and Lateral Loads
6.8.1 Retaining walls not restrained at the top and having a level backfill surface should be
designed for an active soil pressure equivalent to the pressure exerted by a fluid with a
density of 35 pounds per cubic foot (pcf). Where the backfill will be inclined at 2:1
(horizontal:vertical), an active soil pressure of 50 pcf is recommended. These soil pressures
assume that the backfill materials within an area bounded by the wall and a 1:1 plane
extending upward from the base of the wall possess an Expansion Index 50. Geocon
Incorporated should be consulted for additional recommendations if backfill materials have
an El >50.
6.8.2 Retaining walls shall be designed to ensure stability against overturning sliding, excessive
foundation pressure and water uplift. Where a keyway is extended below the wall base with
the intent to engage passive pressure and enhance sliding stability, it is not necessary to
consider active pressure on the keyway.
6.8.3 Where walls are restrained from movement at the top, an additional uniform pressure of
8H psf (where H equals the height of the retaining wall portion of the wall in feet) should be
added to the active soil pressure where the wall possesses a height of 8 feet or less and 12H
where the wall is greater than 8 feet. For retaining walls subject to vehicular loads within a
horizontal distance equal to two-thirds the wall height, a surcharge equivalent to two feet of
fill soil should be added (total unit weight of soil should be taken as 130 pcI).
6.8.4 Soil contemplated for use as retaining wall backfill, including import materials, should be
identified in the field prior to backfill. At that time Geocon Incorporated should obtain
samples for laboratory testing to evaluate its suitability. Modified lateral earth pressures
may be necessary if the backfill soil does not meet the required expansion index or shear
strength. City or regional standard wall designs, if used, are based on a specific active lateral
earth pressure and/or soil friction angle. In this regard, on-site soil to be used as backfill may
or may not meet the values for standard wall designs. Geocon Incorporated should be
consulted to assess the suitability of the on-site soil for use as wall backfill if standard wall
designs will be used.
6.8.5 Unrestrained walls will move laterally when backfilled and loading is applied. The amount
of lateral deflection is dependent on the wall height, the type of soil used for backfill, and
loads acting on the wall. The wall designer should provide appropriate lateral deflection
Project No. 06442-32-29 - 15 - May 20, 2019
quantities for planned retaining walls structures, if applicable. These lateral values should be
considered when planning types of improvements above retaining wall structures.
6.8.6 Retaining walls should be provided with a drainage system adequate to prevent the buildup
of hydrostatic forces and should be waterproofed as required by the project architect. The
use of drainage openings through the base of the wall (weep holes) is not recommended
where the seepage could be a nuisance or otherwise adversely affect the property adjacent to
the base of the wall. The above recommendations assume a properly compacted granular
(El s50) free-draining backfill material with no hydrostatic forces or imposed surcharge
load. A typical retaining wall drainage detail is presented on Figure 4. If conditions different
than those described are expected, or if specific drainage details are desired, Geocon
Incorporated should be contacted for additional recommendations.
6.8.7 In general, wall foundations having a minimum depth and width of one foot may be
designed for an allowable soil bearing pressure of 2,500 psf, provided the soil within three
feet below the base of the wall has an Expansion Index < 90. The recommended allowable
soil bearing pressure may be increased by 300 psf and 500 psf for each additional foot of
foundation width and depth, respectively, up to a maximum allowable soil bearing pressure
of 4,000 psf.
6.8.8 The proximity of the foundation to the top of a slope steeper than 3:1 could impact the
allowable soil bearing pressure. Therefore, Geocon Incorporated should be consulted where
such a condition is anticipated. As a minimum, wall footings should be deepened such that
the bottom outside edge of the footing is at least seven feet from the face of slope when
located adjacent and/or at the top of descending slopes.
6.8.9 The structural engineer should determine the Seismic Design Category for the project in
accordance with Section 1613.3.5 of the 2016 CBC or Section 11.6 of ASCE 7-10. For
structures assigned to Seismic Design Category of D, E, or F, retaining walls that support
more than 6 feet of backfill should be designed with seismic lateral pressure in accordance
with Section 1803.5.12 of the 2016 CBC. The seismic load is dependent on the retained
height where H is the height of the wall, in feet, and the calculated loads result in pounds per
square foot (psf) exerted at the base of the wall and zero at the top of the wall. A seismic
load of 14H should be used for design. We used the peak ground acceleration adjusted for
Site Class effects, ROAM, of 0.399g calculated from ASCE 7-10 Section 11.8.3 and applied
a pseudo-static coefficient of 0.33.
6.8.10 For resistance to lateral loads, a passive earth pressure equivalent to a fluid density of 300 pcf
is recommended for footings or shear keys poured neat against properly compacted granular
fill soils or undisturbed formational materials. The passive pressure assumes a horizontal
Project No. 06442-32-29 -16- May 20, 2019
surface extending away from the base of the wall at least five feet or three times the surface
generating the passive pressure, whichever is greater. The upper 12 inches of material not
protected by floor slabs or pavement should not be included in the design for lateral resistance.
6.8.11 An ultimate friction coefficient of 0.35 may be used for resistance to sliding between soil
and concrete. This friction coefficient may be combined with the passive earth pressure
when determining resistance to lateral loads.
6.8.12 The recommendations presented above are generally applicable to the design of rigid
concrete or masonry retaining walls having a maximum height of 12 feet. In the event that
walls higher than 12 feet are planned, Geocon Incorporated should be consulted for
additional recommendations.
6.9 Preliminary Pavement Recommendations - Flexible and Rigid
6.9.1 The following preliminary pavement design sections are based on our experience with soil
conditions within the surrounding area. 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 and are not for construction. 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.
6.9.2 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 Slate 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 (AC! 330R-08). The
structural sections presented herein are in accordance with City of Carlsbad minimum
requirements for private commercial/industrial developments. Table 6.9 summarizes
preliminary pavement sections.
Project No. 06442-32-29 -17- May 20, 2019
TABLE 6.9
PRELIMINARY PAVEMENT DESIGN SECTIONS
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/Fire Lane -
Trash Enclosure Apron N/A N/A N/A 7•5**
Civil engineer should provide TI for final pavement design.
**City of Carlsbad minimums for Private Commercial/Industrial developments.
6.9.3 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.
6.9.4 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 3/4-inch maximum size aggregate.
6.9.5 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 above optimum moisture content. Asphalt concrete should be compacted to
at least 95 percent of the laboratory Hveem density in accordance with ASTM D 2726.
6.9.6 Loading aprons such as trash bin enclosures and heavy truck areas should utilize Portland
cement concrete as presented in Table 8.10 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.
Project No. 06442-32-29 - IS - May 20, 2019
6.9.7 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.
* 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 ACI guide and should be provided by the
project structural engineer.
6.9.8 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.
6.10 Storm Water Management
6.10.1 We understand that low-impact development (LID) integrated management practices
(IMP's) are included in the design of the subject site.
6.10.2 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
Project No. 06442-32-29 19- May 20, 2019
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.
6.10.3 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
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.
6.10.4 A stormwater infiltration feasibility investigation was previously provided and is included in
Appendix B.
6.11 Slope Maintenance
6.11.1 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.
Project No. 06442-32-29 -20- May 20, 2019
6.12 Site Drainage and Moisture Protection
6.12.1 Adequate site drainage is critical to reduce the potential for differential soil movement,
erosion and subsurface seepage. Under no circumstances should water be allowed to pond
adjacent to footings. The site should be graded and maintained such that surface drainage is
directed away from 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.
6.12.2 Underground utilities should be leak free. Utility and irrigation lines should be checked
periodically for leaks, and detected leaks should be repaired promptly. Detrimental soil
movement could occur if water is allowed to infiltrate the soil for prolonged periods of time.
6.13 Foundation Plan Review
6.13.1 Geocon Incorporated should review the foundation plans for the project prior to final design
submittal to evaluate whether additional analyses and/or recommendations are required.
Project No. 06442-32-29 -21 - May 20, 2019
- r -
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*
THE GEOGRAPHICAL INFORMATION MADE AVAILABLE FOR DISPLAY WAS PROVIDED BY GOGGLE EARTH,
SUBJECT TO A LICENSING AGREEMENT. THE INFORMATION IS FOR ILLUSTRATIVE PURPOSES ONLY; IT IS
NOT INTENDED FOR CLIENTS USE DR 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 COR)
GEOTECHNICAL • ENVIRONMENTAL u MATERIALS
6960 FLANDERS DRIVE SAN DIEGO, CALIFORNIA 92121- 2974
PHONE 858 558-6900 - FAX 858 558-6159
RM/AML DSKIGTYPD
OAKMONT OF CARLSBAD
CARLSBAD OAKS NORTH BUSINESS PARK - LOT 1
CARLSBAD, CALIFORNIA
DATE 05-17-2019 1 PROJECT NO. 06442-32-29 1 FIG. 1
PAD GRADE
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I WALL/ COLUMN FOOTING DIMENSION DETAIL I
GEOCON (4 INCORPORATED
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
OAKMONT OF CARLSBAD
CARLSBAD OAKS NORTH BUSINESS PARK - LOT 1
CARLSBAD, CALIFORNIA
DATE 05-17- 2019 PROJECT NO. 06442 -32-29 1 FIG. 3
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Ar
—
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WATER PROOFING PER OSHA
PER ARCHITECT
2/3 H MIRAFI 140N FILTER FABRIC
- (OR EQUIVALENT)
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- PER ARCHITECT
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- ...— (MIRADRAIN 6000
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- /(1 CU.FTJFT.)
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I I PERFORATED PVC PIPE
OR TOTAL DRAIN
EXTENDED TO
APPROVED OUTLET
NOTE:
DRAIN SHOULD BE UNIFORMLY SLOPED TO GRAVITY OUTLET
OR TO A SUMP WHERE WATER CAN BE REMOVED BY PUMPING
CONCRETE GROUND SURFACE BROWDITCH
RETAINING
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GEOCON Ira) INCORPORATED
GEOTECHNICAL U ENVIRONMENTAL U MATERIALS
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
RM I AML OSK/GTYPD
OAKMONT OF CARLSBAD
CARLSBAD OAKS NORTH BUSINESS PARK - LOT 1
CARLSBAD, CALIFORNIA
DATE 05-20-2019 PROJECT NO. 06442 - 32 - 29 1 FIG.4
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APPENDIX
APPENDIX A
FINISH GRADE 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 LOT CONDITIONS WITH
LABORATORY EXPANSION INDEX AND WATER-SOLUBLE SULFATE TEST RESULTS
Lot No. Sample at
Finish Grade
Expansion
Index
CBC
Classification Sulfate Exposure
EI-39 (SW Portion) 50 Low Severe (S2)
EI-40 (NW Portion) 74 Medium Moderate (Si)
E141 (NE Portion) 56 Medium Severe (S2)
EI42 (SE Portion) 46 Medium Severe (S2)
Project No. 06442-32-29 May 20, 2019
APPENDIX
STORM WATER MANAGEMENT
FOR
OAKMONT OF CARLSBAD
CARLSBAD OAKS NORTH BUSINESS PARK - LOT I
CARLSBAD, CALIFORNIA
PROJECT NO. 06442-32-29
STORM WATER MANAGEMENT INVESTIGATION
We understand storm water management devices are being proposed in accordance with the 2016 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 I presents the descriptions of the
hydrologic soil groups. If a soil is assigned to a dual hydrologic group (AID, BID, or CID), the first
letter is for drained areas and the second is for undrained areas.
TABLE I
HYDROLOGIC SOIL GROUP DEFINITIONS
Soil Group Soil Group Definition
Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These
A consist 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
C having 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 Point Loma formation.
After completion of the proposed grading operations, the property would consist of compacted fill
over Pont Loma Formation. The compacted fill and formational materials should be classified as Soil
Project No. 06442-32-29 - I - May 20, 2019
Group D. In addition, the USDA website also provides an estimated saturated hydraulic conductivity
for the existing soil. Table 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 2
USDA WEB SOIL SURVEY - HYDROLOGIC SOIL GROUP
Map Unit Approximate Hydrologic kSAr of Most
Map Unit Name Symbol Percentage Soil Group Limiting Layer
of Property (Inches! Hour)
Cieneba coarse sandy loam CiG2 44 D 1.98 -5.95
Huerhuero loam HrD 56 D 0.00-0.06
In-Situ Testing
We performed two Soil Moisture, Inc. Aardvark Permeameter tests at the locations shown on the
attached Geologic Map, Figure 2. Test P-I was located in the bottom of an existing basin. Some
standing water was observed in a portion of this basin. Test P-2 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 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 3
FIELD PERMEAMETER INFILTRATION TEST RESULTS
Geologic Test Depth Field-Saturated Field
Test No. Unit (feet, below grade) Hydraulic Conductivity, Infiltration Rate
k, (inch/hour) (inch/hour)
P-I Qcf 2.4 . 0.0002 0.0001
P-2 Kp 3.75 0.002 0.001
Project No. 06442-32-29 -2- May 20, 2019
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.
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. The fill has been or will be 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 5 to 10 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. If the infiltration BMP's extended
below the compacted fill, partial infiltration may be feasible.
Because of the uncertainty offill 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 geotechnically 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
Project No. 06442-32-29 -3- May 20, 2019
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.
Infiltration Rates
The results of the unfactored infiltration rates (i.e. field saturated hydraulic conductivity) for Tests P-I
and P-2 were 0.0002 inches per hour (iph) and 0.002 iph, respectively. After applying a feasibility
factor of safety of 2.0, the infiltration rates obtained for P-I and P-2 are 0.0001 and 0.001 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. 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, both 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
Project No. 06442-32-29 -4 - May 20, 2019
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
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 to 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.5-1 or Form 1-9) that helps
the project civil engineer estimate the factor of safety based on several factors. Table 4 describes the
suitability assessment input parameters related to the geotechnical engineering aspects for the factor of
safety determination.
TABLE 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 or Use of well permeameter
or simple texture analysis to borehole methods with
. Direct measurement with
estimate short-term accompanying
continuous boring log, localized (i.e. small-
infiltration rates. Use of Direct measurement of scale) infiltration testing
Assessment Methods well permeameter or infiltration area with methods at relatively high
borehole methods without localized in filtration 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 Silty and clayey soils Loamy soils Granular to slightly
Texture 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
Project No. 06442-32-29 -5 - May 20, 2019
Based on our geotechnical investigation and the previous table, Table 5 presents the estimated factor
values for the evaluation of the factor of safety. This table only presents the suitability 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 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 I 0.25
Suitability Assessment Safety Factor, SA = Zp 2.5
The project civil engineer should complete Worksheet 13.5-I or Form 1-9 using the data provided above.
Additional information is required to evaluate the design factor of safety.
Project No. 06442-32-29 -6- . May 20, 2019
Part 1- Full Infiltration Feasibility Screening Criteria
Would infiltration of the full design volume be feasible from a physical perspective without any
undesirable consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
Is the estimated reliable infiltration rate below proposed facility locations greater than
1 0.5 inches per hour? The response to this Screening Question shall be based on a X
comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D.
Provide basis: Based on the results of permeability testing in two locations at the site, the unfactored infiltration
rates were measured to be 0.0002 inches/hour (iph), and 0.002 iph using a constant head borehole permeameter
placed inside a 4-inch diameter boring between 2 and 4 feet below existing grades. If applying a feasibility
factor of safety of 2.0, the infiltration rates would be 0.0001 iph and 0.001 iph. Based on the USDA Web Soil
Survey website, the underlying soils are classified as Cieneba sandy loam and Huerhuero loam and belong to
Hydrologic Soil Group 0, which are generally not considered suitable for infiltration BMP's. The existing
compacted fill should be classified as Hydrologic Soil Group 0, which is not suitable for infiltration BMP's.
Information collected from the USDA website is attached. The Aardvark Permeameter test results are presented
in Appendix A. In accordance with the Riverside County storm water procedures, which reference the United
States Bureau of Reclamation Well Permeameter Method (USBR 7300), the saturated hydraulic conductivity is
equal to the unfactored infiltration rate.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of
geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors)
2 that cannot be mitigated to an acceptable level? The response to this Screening X
Question shall be based on a comprehensive evaluation of the factors presented in
Appendix C.2.
Provide basis: Natural slopes and fill slopes surround the property. Full infiltration adjacent to descending slopes
is not recommended due to slope instability and daylight water seepage issues. The landslide potential is very
low to negligible. Groundwater mounding is not likely to occur. Existing and proposed utilities would be in
close proximity to the proposed BMP's. The potential for lateral water migration and distress to the public and
private roadway improvements and proposed buildings is high.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
0
Criteria Screening Question Yes No
Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of
groundwater contamination (shallow water table, storm water pollutants or other
3 factors) that cannot be mitigated to an acceptable level? The response to this Screening X
Question shall be based on a comprehensive evaluation of the factors presented in
Appendix C.3.
Provide basis: Groundwater is not located within 10 feet from the proposed infiltration BMP.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
Can infiltration greater than 0.5 inches per hour be allowed without causing potential
water balance issues such as change of seasonality of ephemeral streams or increased
4 discharge of contaminated groundwater to surface waters? The response to this X
Screening Question shall be based on a comprehensive evaluation of the factors
presented in Appendix C.3.
Provide basis: It is our opinion there are no adverse impacts to water balance impacts to stream flow, or impacts
on any downstream water rights. It should be noted that researching downstream water rights or evaluating
water balance issues to stream flows is beyond the scope of the geotechnical consultant.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability.
If all answers to rows I - 4 are "Yes" a full infiltration design is potentially feasible. The
Part I feasibility screening category is Full Infiltration No.
Result* If any answer from row 1-4 is "No". infiltration may be possible to some extent but would not
See
Part 2
generally be feasible or desirable to achieve a "full infiltration" design. Proceed to Part 2
*To be completed using gathered site information and best professional judgment considering the definition of MEP in
the M54 Permit. Additional testing and/or studies may be required by City Engineer to substantiate findings.
Part 2— Partial Infiltration vs. No Infiltration Feasibility Screening Criteria
Would infiltration of water in any appreciable amount be physically feasible without any negative
consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
Do soil and geologic conditions allow for infiltration in any appreciable rate or volume?
5 The response to this Screening Question shall be based on a comprehensive evaluation X
of the factors presented in Appendix C.2 and Appendix D.
Provide basis: The infiltration test results did not meet the minimum threshold of 0.01 iph for partial infiltration.
Saturating compacted fill may result in settlement and distress to nearby public roadway improvements and
proposed private improvements and structures.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
Can Infiltration in any appreciable quantity be allowed without increasing risk of
geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors)
6 that cannot be mitigated to an acceptable level? The response to this Screening X
Question shall be based on a comprehensive evaluation of the factors presented in
Appendix C.2.
Provide basis: The adverse impacts of partial infiltration could be reasonably mitigated to acceptable levels using
side liners and a subdrain. However, infiltrating into compacted fill is not recommended. Any infiltration BMP's
should be founded in the formational materials and side liners should be used to prevent lateral water migration
and daylight water seepage from adversely impacting the compacted fill and slopes.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
Criteria Screening Question Yes No
Can Infiltration in any appreciable quantity be allowed without posing significant risk
for groundwater related concerns (shallow water table, storm water pollutants or other
factors)? The response to this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.3.
Provide basis: Groundwater is not located within approximately 10 feet from the bottom of the proposed basins.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
Can infiltration be allowed without violating downstream water rights? The response to
8 this Screening Question shall be based on a comprehensive evaluation of the factors X
presented in Appendix C.3.
Provide basis: Geocon is not aware of any downstream water rights that would be affected by incidental
infiltration of storm water. Researching downstream water rights is beyond the scope of the geotechnical
consultant.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.
If all answers from row 14 are yes then partial infiltration design is potentially feasible.
Part 2 The feasibility screening category is Partial Infiltration No
Result* If any answer from row 5-8 is no, then infiltration of any volume is considered to be Infiltration
infeasible within the drainage area. The feasibility screening category is No Infiltration.
"To be completed using gathered site information and best professional judgment considering the definition of MEP in
the MS4 Permit. Additional testing and/or studies may be required by City Engineer to substantiate findings
V710/GEocoN
Aardvark Permeameter Data Analysis
Project Name: Oakmont Senior Living Date: 9/15/2017
Project Number: 06442-32-29 By: DG
Test Number: P-i
Borehole Diameter, d (in.): 4.00 Ref. EL (feet, MSL): 238.0
Borehole Depth, H (In): 29.00 Bottom EL (feet, MSL): 235.6
Distance Between Reservoir & Top of Borehole (In.): 28.00
Estimated Depth to Water Table, S (feet): ioo
Height APM Raised from Bottom (In.): 2.00
Pressure Reducer Used: No
Distance Between Resevoir and APM Float, 0 (in.): 4775
Head Height Calculated, h (in.): 5.66
Head Height Measured, h (in.): 5700
Distance Between Constant Head and Water Table, I (in.): 1228.00
C
E
C
0.03
0.02
0.01
0.00
10 20 30 40
Time (mm)
50 60
Soil Matric Flux Potential. '...
m I 0.00004 IinzImIn
Field-Saturated Hydraulic Conductivity (Infiltration Rate)
= In/mn 1 0.0002 in/hr
(4)GEOCON
Aardvark Permeameter Data Analysis
Project Name: Oakmont Senior living Date: 9/15/2017
Project Number: 06442-32-29 By: DG
Test Number: P-2 Ref. EL (feet, MSL): 253.0
Bottom EL (feet, MSL): 249.3
Borehole Diameter, d (In.): 4.00
Borehole Depth, H (in): 45.00
Distance Between Reservoir & Top of Borehole (in.) 28.00
Estimated Depth to Water Table, S (feet): 100.00
Height APM Raised from Bottom (In.): 2.00
Pressure Reducer Used:l No
Distance Between Resevoir and APM Float, 0 (in.): 63.75 I
Head Height Calculated, h (in.): 5.71 I
Head Height Measured, h (in.): 73.00J
Distance Between Constant Head and Water Table, L (in.): 1228.00 I
10 20 30 40 50 60 70 80
Time (mm)
Soil Matric Flux Potential.
m I 0.0003 Iin2/mln
Field-Saturated Hydraulic Conductivity (Infiltration Rate)
= 2.72E-05 un/mm 0.002 tin/hr
33" 2O'N
Soil Map—San Diego County Area, California
(Carlsbad Oaks North - Lot 1) [I,
33" 8 211
ilk
lop
c' G
4r
r
?
:i v'
./"'. -*',' •' ..
wrilli
33"911"N
ii ihiSS(d
338'11"N
Map Scale: 1:1,9(X) if printed on Alandscape(11" x 8.5") sheet.
—Meters N 0 25 50 100 iti
A -
J\ 0 50 100 200
Map projection: Web Mercator Corner wocdina: WGS84 Edge tics: UTM Zone 11 N WGS84
USDA Natural Resources Web Soil Survey 9/20/2017
Conservation Service National Cooperative Soil Survey Page 1 of 3
Soil Map—San Diego County Area, California Carlsbad Oaks North - Lot 1
Map Unit Legend
San Diego County Area, California (CA638)
• Map Unit Symbol Map Unit Name Acres in AOl Percent of AOl
C1G2
•
Cieneba coarse sandy loam,
30 to 65 percent slopes, ero
ded
3.1 43.7%
HrD Huerhuero loam, 9 to 15
percent slopes
4.0 56.3%
Totals for Area of Interest • 7.2 100.0%
Natural Resources • Web Soil Survey • 9/20/2017
Conservation Service National Cooperative Soil Survey Page 3 of 3
Map Unit Description: Cleneba coarse sandy loam, 30 to 65 percent slopes, ero ded—San Carlsbad Oaks North - Lot 1
Diego County Area, California
San Diego County Area, California
CIG2—Cieneba coarse sandy loam, 30 to 65 percent slopes,
ero ded
Map Unit Setting
National map unit symbol: hb9s
Elevation: 500 to 4,000 feet
Mean annual precipitation: 12 to 35 inches
Mean annual air temperature: 57 to 64 degrees F
Frost-free period: 200 to 300 days
Farmland classification: Not prime farmland
Map Unit Composition
Cieneba and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transacts of
the mapunit.
Description of Cieneba
Setting
Landform: Hills
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down-slope shape: Convex
Across-slope shape: Convex
Parent material: Residuum weathered from granite and
granodiorite
Typical profile
HI - 0 to 10 inches: coarse sandy loam
H2 - 10 to 14 inches: weathered bedrock
Properties and qualities
Slope: 30 to 65 percent
Depth to restrictive feature: 4 to 20 inches to paralithic bedrock
Natural drainage class: Somewhat excessively drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): High
(1.98 to 5.95 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: Very low (about 1.0 inches)
Interpretive groups
Land capability classification (irrigated): 7e
Land capability classification (nonirrigated): 7e
Hydrologic Soil Group: 0
Ecological site: SHALLOW LOAMY (1975) (ROI9XD060CA)
Hydric soil rating: No
Natural Resources Web Soil Survey 9/20/2017
Conservation Service National cooperative Soil Survey Page 1 of 2
Map Unit Description: Cieneba coarse sandy loam, 30 to 65 percent slopes, ero ded—San Carlsbad Oaks North - Lot 1
Diego County Area, California
Minor Components
Vista
Percent of map unit: 10 percent
Hydric soil rating: No
Las posas
Percent of map unit: 5 percent
Hydric soil rating: No
Data Source Information
Soil Survey Area: San Diego County Area, California
Survey Area Data: Version 10, Sep 12, 2016
Natural Resources Web Soil Survey 9/20/2017
Conservation Service National Cooperative Soil Survey Page 2 of 2
Map Unit Description: Huerhuero loam, 9 to 15 percent slopes—San Diego County Area, Carlsbad Oaks North - Lot 1
California
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-0t012inches: 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: 9t0 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 (Ksaf): 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
us Natural Resources Web Soil Survey 9/20/2017
Conservation Service National Cooperative Soil Survey Pagel of 2
Map Unit Description: Huertiuero loam, 9 to 15 percent slopes—San Diego County Area, Carlsbad Oaks North - Lot 1
California
Ecological site: CLAYPAN (1975) (ROI9XDO6ICA)
Hydric soil rating: No
Minor Components
Las fibres
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
Data Source Information
Soil Survey Area: San Diego County Area, California
Survey Area Data: Version 10, Sep 12, 2016
VDA Natural Resources Web Soil Survey 9/20/2017
Conservation Service National Cooperative Soil Survey Page 2012
APPENDIX
RECOMMENDED GRADING SPECIFICATIONS
1. GENERAL
1.1 These Recommended Grading Specifications shall be used in conjunction with the
Geotechnical Report for the project prepared by Geocon. 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.
2. DEFINITIONS
2.1 Owner shall refer to the owner of the property or the entity on whose behalf the grading
work is being performed and who has contracted with the Contractor to have grading
performed.
2.2 Contractor shall refer to the Contractor performing the site grading work.
2.3 Civil Engineer or Engineer of Work shall refer to the California licensed Civil Engineer
or 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 Soil Engineer shalt 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 shalt 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 3h 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 1 '/ 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.
01 rev. 07/2015
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
GI 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
TYPICAL CANYON DRAIN DETAIL
NA11JRALOIR -i - --
S. MUMUMAND
COUMIUM RIMMAL
BEDROCK
SEE DETAIL BELOW
NOM FINAL 2W OF PE AT OUTlET
SMALLGEMON-P ORATm-
V OW PECRATW
SIRORAJN PIPE
c:?:• •:. ....
CUBIC FEETI POW 0FOP9
GRADED GRAVEL SIUNDWBY NIRAR I40NC (OR EQUNM9 FILTER FAaRIC
NOTES:
I...8.INCH DIAMETER. SCHEDULE 80 PVC PERFORATED PIPE FOR FILLS
IN EXCESS OF 100-FEET IN DEFPI OR A PIPE LENGTh OF LONGER THAN 500 FEET.
2-...A-INCH DIAMETER. SCHEDULE 40 PVC PERFORATED PIPE FOR FILLS
LESS THAN 100-FEET IN DEPTH OR A PIPE LENGTH SHORTER THAN 600 FEET.
NO SCALE
7.2 Slope drains within stability fill keyways should use 4-inch-diameter (or lager) pipes.
GI rev. 07/2015
TYPICAL STABILITY FILL DETAIL
FORM4IIOPA4L
MATERIAL
1.....BECAVAT! BACIUT AT 1:1 U9CUNATION Q.MB.ESS OTI4ERWE NOT).
2.-.BABE OF STABILiTY FiLL TO BE 3 FEET INTO FORMAnONAL MA1EAL. SLOPING A MININVJM 5% INTO SLOPE.
3....SIASlU1Y FBi. TO BE COMPOSED OF PRCPE.YCCAC1W GRANILAR SOIL
4.....CHIMNEY DRAINS TO BE APPROVED PRffASCAThDCISMNEY DRAIN PANELS (MACRAJN OM OR ECIJIVALEHT)
SPACED APAROISMA1ELY 20 FCET CENTER TO CCI4IERMD 4 FT WiDE. CLOSER SPACING MAY BE REQUIRED F
SBEPAG€ IS ENCOUNTERED.
L.-FILTER MATERIAI.TD BE 31441C11, OPEN.GRADED CRUSHED ROCK ENCLOSED IN APPROVED FILTER FABRIC (MIRAFI 14CNC
L.COLLWTOR PIPE TO BE 44NCI4 MINNUM OIN4ETER. PERFORATED. THMWAILLED PVC SCHEME 40 OR
EQUIVALENT. AND SLOPED TO DRAIN AT 1 PERCENT MINIWJMTO APPROVED OUT%.ET.
7.3 The actual subdrain locations will be evaluated in the field during the remedial grading
operations. Additional drains may be necessary depending on the conditions observed and
the requirements of the local regulatory agencies. Appropriate subdrain outlets should be
evaluated prior to finalizing 40-scale grading plans.
7.4 Rock fill or soil-rock fill areas may require subdrains along their down-slope perimeters to
mitigate the potential for buildup of water from construction or landscape irrigation. The
subdrains should be at least 6-inch-diameter pipes encapsulated in gravel and filter fabric.
Rock fill drains should be constructed using the same requirements as canyon subdrains.
GI rev. 07/2015
7.5 Prior to outletting, the final 20-foot segment of a subdrain that will not be extended during
future development should consist of non-perforated drainpipe. At the non-perforated/
perforated interface, a seepage cutoff wall should be constructed on the downslope side of
the pipe.
TYPICAL CUT OFF WALL DETAIL
FRONT VIEW
NO SCAI.E
SIDE VIEW
CUT.PPWML r MISt (TYP)
eMMfiU8MVMPM
NO SCALE
7.6 Subdrains that discharge into a natural drainage course or open space area should be
provided with a permanent headwall structure.
GI rev. 07/2015
TYPICAL HEADWALL DETAIL
FRONT VIEW
MR _T
-•:; ..i:& ir
4. Ed
;:. ;:::j
NO SCALE
SIDE 'id
N015 HEAALLSKOUD OUTLET AT TOE OF FILL SLOPE NO SCALE
OR INTO CONTROLLED SURFACE DRAINAGE
7.7 The final grading plans should show the location of the proposed subdrains. After
completion of remedial excavations and subdrain installation, the project civil engineer
should survey the drain locations and prepare an "as-built" map showing the drain
locations. The final outlet and connection locations should be determined during grading
operations. Subdrains that will be extended on adjacent projects after grading can be placed
on formational material and a vertical riser should be placed at the end of the subdrain. The
grading contractor should consider videoing the subdrains shortly after burial to check
proper installation and functionality. The contractor is responsible for the performance of
the drains.
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 lans. 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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