HomeMy WebLinkAboutCT 2018-0003; MAGNOLIA BRADY; GEOTECHNICAL INVESTIGATION; 2018-01-17I I ! I
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GEOTECHNICAL INVESTIGATION
1534 MAGNOLIA AVENUE
CARLSBAD, CALIFORNIA
l,. --\1 ED
OC T O ~ 2019
LAND DEVELOP\ti~NT
ENGINEERlr G
PREPARED FOR
ASTHON 3, LLC
RANCHO MISSION VIEJO, CALIFORNIA
JANUARY 17, 2018
PROJECT NO. G2192-52-01 ~
\i
GEOCON
INCORPORATED
GEOTECHNICA L ■
Project No. G2l92-52-01
January 17, 2018
Ashton 3, LLC
5 Hoya Street
Rancho Mission Viejo, California 92694
Attention: Mr. Taylor Ashton
Subject: GEOTECHNICAL INVESTIGATION
1534 MAGNOLIA A VENUE
CARLSBAD, CALIFORNIA
Dear Mr. Ashton:
In accordance with your request, we performed this geotechnical investigation for the proposed 7-lot
residential development in Carlsbad, California. The accompanying report presents the results of our
study and our conclusions and recommendations regarding the geotechnical aspects of project
development. The results of our study indicate that the site can be developed as planned, provided the
recommendations of this report are followed.
Should you have questions regarding this report, or ifwe may be of further service, please contact the
undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
MRL:SFW:JH:dmc
(e-mail)
(3)
Addressee
Mr. Robert C. Ladwig
&e~
GE 2714
6960 Flanders Drive ■ San Diego, California 92121-2974 ■ Telephone 858.558.6900 ■ Fax 858.558.6159
TABLE OF CONTENTS
1. PURPOSE AND SCOPE ................................................................................................................. I
2. SITE AND PROJECT DESCRIPTION ........................................................................................... 1
3. GEOLOGIC SETTING .................................................................................................................... 2
4. SOIL AND GEOLOGIC CONDITIONS ........................................................................................ 2
4.1 Undocumented Fill (Qudf) .................................................................................................... 2
4.2 Old Paralic Deposits (Qop) .................................................................................................... 2
5. GROUNDWATER .......................................................................................................................... 3
6. GEOLOGIC HAZARDS ................................................................................................................. 3
6.1 Faulting and Seismi city ......................................................................................................... 3
6.2 Ground Rupture ..................................................................................................................... 5
6.3 L iquefaction ........................................................................................................................... 5
6.4 Seiches and Tsunamis ............................................................................................................ 6
6.5 Landslides .............................................................................................................................. 6
7. CONCLUSIONS AND RECOMMENDATIONS ........................................................................... 7
7.1 General ................................................................................................................................... 7
7.2 Excavati on and Soil Characteri stics ...................................................................................... 8
7.3 Grading .................................................................................................................................. 9
7 .4 Temporary Excavations ....................................................................................................... l 0
7.5 Seismic Design Criteria ....................................................................................................... 10
7.6 Shallow Foundations ........................................................................................................... 12
7.7 Concrete Slabs-on-Grade ..................................................................................................... 13
7.8 Post-Tensioned Foundation System Recommend ations ...................................................... 14
7 .9 Concrete Flatwork ............................................................................................................... 16
7.10 RetainingWalls ................................................................................................................... 17
7.1 1 Lateral Loading .................................................................................................................... 18
7.12 Preliminary Pavement Recommendations ........................................................................... 19
7.13 Site Drainage and Moisture Protecti on ................................................................................ 22
7.1 4 Gradin g, Improvement and Foundation Plan Rev iew .......................................................... 22
LIMITATIONS AND UNIFORMITY OF CONDITIONS
MAPS AND ILLUSTRATIONS
Figure 1, Vicinity Map
Figure 2, Geologic Map
Figure 3, Wall/Column Footing Dimension Detail
Figure 4, Typical Retaining Wall Drain Detail
APPENDIX A
FIELD INVESTIGATION
F igures A-1 -A-9, Exploratory Trench Logs
TABLE OF CONTENTS (Concluded)
APPENDIX B
LABO RA TORY TESTING
Table B-1, Summary of Laboratory Maximum Density and Optimum Moisture Content Results
Table B-II, Summary of Laboratory Direct Shear Results
Table B-III, Summary of Laboratory Expansion Index Test Results
Table B-IV, Summary of Laboratory Water-Soluble Su lfate Test Results
Table B-V, Summary of Laboratory Resistance Value (R-Value) Test Results
Figure B-1 , Gradation Curves
APPENDIX C
STORM WATER MANAGEMENT INVESTIGATION
APPENDIX D
RECOMMENDED GRADING SPECIFICATIONS
LIST OF REFERENCES
GEOTECHNICAL INVESTIGATION
1. PURPOSE AND SCOPE
This report presents the results of our geotechnical investigation for the proposed residential
development located at 1534 Magnolia A venue in the City of Carlsbad, California (see Vicinity Map,
Figure 1). The purpose of this geotechnical investigation is to evaluate the surface and subsurface soil
conditions, general site geology, and to identify geotechnical constraints that may impact the planned
improvements to the property. In addition, this report provides recommendations for the 2016 CBC
seismic design criteria, grading, pavement, shallow foundations, concrete slabs-on-grade, concrete
flatwork, retaining wall s, lateral loads, and storm water best management practices (BMP)
recommendations; and discussions regarding the local geologic hazards including faulting and
seismic shaking.
This report is limited to the area proposed for the construction of the new development and associated
improvements as shown on the Geologic Map, Figure 2. We used the preliminary grading plan
prepared by Civil Landworks (2018) as the base for the Geologic Map.
The scope of this investigation included rev1ewmg readily available published and unpublished
geologic literature (see List of References); performing engineering analyses; and preparing of this
report. We also advanced 9 exploratory trenches to a maximum depth of about 12 feet, performed
percolation/infiltration testing, sampled soil and performed laboratory testing. Appendix A presents
the exploratory trench logs and details of the field investigation. The details of the laboratory tests
and a summary of the test results are shown in Appendix B and on the trench logs in Appendix A.
Appendix C presents a summary of our storm water management investigation.
2. SITE AND PROJECT DESCRIPTION
The site is located at the northeast comer of Magnolia Avenue and Brady Circle and can be accessed
from both streets. A residential structure exists in the northeast corner of the site. The remainder of
property is covered with seasonal grasses and shrubs and appears to have remained undeveloped for
at least the last 50 years. The property is relatively flat and gently descends to the southwest at
elevations of about 150 to 160 feet above mean sea level (MSL).
We understand the planned development includes constructing 7 residential lots with associated
utilities, driveways, storm water basins and landscaping. Access to the lots will be from Brady Circle.
Maximum cut and fill depths are on the order of 2 feet across the site and up to 5 feet for the
proposed biofiltration basins. We expect the proposed structures would likely be supported on
conventional shallow or post-tensioned foundation systems founded in properly compacted fill.
Project No. 02192-52-0 I -I -January 17, 2018
Individual lot storm water management devices will be constructed on the property and will likely be
extended into the Old Parali c Deposits materials.
3. GEOLOGIC SETTING
The site is located in the western portion of the coastal plain within the southern portion of the
Peninsular Ranges Geomorphi c Province of south ern California. The Peninsular Ranges is a geologic
and geomorphic province that extends from the Imperial Valley to the Pacific Ocean and from the
Transverse Ranges to the north and into Baja Cali fornia to the south. The coastal plain of San Diego
County is underlai n by a th ick sequence of re latively undisturbed and non-conformable sedimentary
rocks that thicken to the west and range in age from Upper Cretaceous through the Pleistocene with
intermittent deposition. The sedimentary units are deposited on bedrock Cretaceous to Jurassic age
igneous and metavolcanic rocks. Geomorphically, the coastal plain is characterized by a series of
twenty-one, stair-stepped marine terraces (youn ger to the west) that have been di ssected by west
flowing rivers. The coastal plain is a relatively stable block that is di ssected by relatively few faults
consisting of the potentially active La Nacion Fault Zone and the active Rose Canyon Fault Zone.
The Peninsular Ranges Province is also dissected by the Elsinore Fault Zone that is associated with
and sub-parallel to the San Andreas Fault Zone, which is the plate boundary between the Pacific and
North American Plates.
4. SOIL AND GEOLOGIC CONDITIONS
We encountered undocumented fill (Qudf) associated with the existing development overlying Old
Paralic Deposits (Qop). The trench lo gs (Appendix A) and the Geologic Map (F igure 2), show the
approximate occurrence, distribution, and description of each unit encountered during our field
investigation. The surficial so il and geologic units are described herein in order of increasing age.
4.1 Undocumented Fill (Qudf)
We encountered undocumented fill in all of our exploratory trenches that varied in thickness between
½ and 3 feet. The fi ll generally consists of loose, dry to damp, light brown to reddish brown, silty
sand and possess a "very low" to "low" expansion potential ( expansion index of 50 or less). These
materials are un suitab le in their present condition, and will req uire remedial grading in the areas of
the proposed improvements.
4.2 Old Paralic Deposits (Qop)
The Quaternary-age Old Paralic Deposits exist below the undocumented fill across the site. These
deposits generally consist of med ium dense to dense, light to dark reddish brown and olive brown,
silty to clayey, fine to medium sand and stiff, olive brown, sandy clay. The Old Paralic Deposits
typically possess a "very low" to "medium" expansion potential ( expansion index of 90 or less) and a
Project No. 02192-52-01 -2 -January 17, 20 18
"SO" sulfate class. The Old Paralic Deposits are considered acceptable to support the planned fill and
foundation loads for the development.
5. GROUNDWATER
We did not encountered groundwater during our field investigation to the maximum depth explored
of 12 feet. We expect groundwater is present at depths of greater than 50 feet. We do not expect
groundwater to significantly impact project development as presently proposed. It is not uncommon
for groundwater or seepage conditions to develop where none previously existed. Groundwater and
seepage is dependent on seasonal precipitation, irrigation, land use, among other factors, and varies as
a result. Proper surface drainage wi ll be important to future performance of the project.
6. GEOLOGIC HAZARDS
6.1 Faulting and Seismicity
Based on our site investigation and a review of published geologic maps and reports, the site is not
located on known active, potentially active or inactive fault traces as defined by the California
Geological Survey (CGS). The CGS considers a fault seismically active when evidence suggests
seismic activity within roughly the last 11 ,000 years.
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 Rose
Canyon Fault zone and the Newport-Inglewood Fault are the closest known active faults, located
approximately 7 miles west of the site. Earthquakes that might occur on the Newport-Inglewood or
Rose Canyon Fault Zones or other faults within the southern California and northern Baja California
area are potential generators of significant ground motion at the site. The estimated deterministic
maximum earthquake magnitude and peak ground acceleration for the Newport-Inglewood Fault are 7.5
and 0.36g, respectively. Table 6.1.1 lists the estimated maximum earthquake magnitude and peak
ground acceleration for the most dominant fau lts 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 (2007) NGA USGS 2008 acceleration-attenuation
relationships.
Project No. G2 I 92-52-0 I -3 -January 17, 2018
TABLE 6.1 .1
DETERMINISTIC SPECTRA SITE PARAMETERS
Maximum Peak Ground Acceleration
Fault Name Distance from Earthquake Boore-Campbell-Chiou-Si te (miles) Magnitude Atkinson Bozorgnia Youngs (Mw) 2008 (g) 2008 (g) 2007 (g)
Newport-Inglewood 7 7.50 0.30 0.29 0.3 6
Rose Canyon 7 6.90 0.26 0.28 0.30
Coronado Bank 21 7.40 0.15 0.11 0.13
Palos Verdes Connected 21 7.70 0.17 0.12 0.15
Elsinore 22 7.85 0.17 0.12 0.16
Palos Verdes 35 7.30 0.10 0.07 0.07
San Joaquin Hills 35 7.10 0.09 0.09 0.07
Earthquake Valley 43 6.80 0.06 0.05 0.04
San Jacinto 47 7.88 0.10 0.07 0.09
Chino 47 6.80 0.06 0.04 0.03
We used the computer program EZ-FRISK to perform a probabilistic seismic hazard analysis. The
computer program EZ-FRISK operates under the assumpti on that the occurrence rate of earthquakes
on each mappable Quaternary fault is proportional to the fau lts 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 fo r 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 (2007) NGA USGS 2008 in
the analysis. Table 6.1.2 presents the site-specific probabilistic seismic hazard parameters including
acceleration-attenuation relationships and the probability of exceedence.
Project No. G2192-52-01 -4 -January 17, 2018
TABLE 6.1.2
PROBABILISTIC SEISMIC HAZARD PARAMETERS
Peak Ground Acceleration
Probability of Exceedence Boore-Atkinson, Cam pbell-Bozorgnia, Chiou-Youngs,
2008 (g) 2008 (g) 2007 (g)
2% in a 50 Year Period 0.44 0.44 0.50
5% in a 50 Year Period 0.32 0.32 0.35
I 0% in a 50 Year Period 0.24 0.23 0.25
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 2016 California Building Code (CBC) guidelines currently adopted
by the City of Carlsbad.
The site could be subjected to moderate to severe ground shaking in the event of a major earthquake
on any of the referenced faults or other faults in Southern California. With respect to seismic shaking,
the site is considered comparable to the surrounding developed area.
6.2 Ground Rupture
Ground surface rupture occurs when movement along a fault is sufficient to cause a gap or rupture
where the upper edge of the fault zone intersects the earth surface. The potential for ground rupture is
considered to be negligible due to the absence of active faults at the subject site.
6.3 Liquefaction
Liquefaction typically occurs when a site is located in a zone with seismic activity, onsite soil is
cohesionless or silt/clay with low plasticity, groundwater is encountered within 50 feet of the surface,
and soil re lative densities are less than about 70 percent. If the four of the previous criteria are met, a
seismic event could result in a rapid pore-water pressure increase from the earthquake-generated
ground accelerations. Seismically induced settlement may occur whether the potential for liquefaction
exists or not. The potential for liquefaction and seismically induced settlement occurring within the
site soil is considered to be very low due to the age and dense nature of the Old Paralic Deposits and
the lack of a permanent groundwater table within the upper 50 feet.
Project No. 02192-52-0 I -5 -January 17, 2018
6.4 Seiches and Tsunamis
Seiches are free or standing-wave oscillations of an enclosed water body that continue, pendulum
fashion, after the original driving forces have dissipated. Seiches usually propagate in the direction of
longest axis of the basin. The site located approximately 1 mile from Agua Hedonia Lagoon and is at
a minimum elevation of approximately 150 feet above Mean Sea Level (MSL); therefore, the
potential of seiches to occur is considered to be very low.
A tsunami is a series of long-period waves generated in the ocean by a sudden displacement of large
volumes of water. Causes of tsunamis may include underwater earthquakes, volcanic eruptions or
offshore slope failures . the property is at an elevation of above 150 feet MSL and about 1 mile from
the Pacific Ocean. Therefore, the potential for the site to be affected by a tsunami is negligible.
6.5 Landslides
We did not observe evidence of ancient landslide deposits at the site during the geotechnical
investigation. Based on observations during our field investigation, it is our opinion that landslides
are not present at the subject property or at a location that could impact the proposed development.
Proj ect No. 02192-52-01 -6 -January 17, 2018
7. CONCLUSIONS AND RECOMMENDATIONS
7.1 General
7.1.1 From a geotechnical engineering standpoint, we opine the site is suitable for the proposed
residential development provided the recommendations presented herein are implemented
in design and construction of the project.
7.1.2 With the exception of possible moderate to strong seismic shaking, we did not observe
significant geologic hazards or know of them to exist on the site that would adversely
affect the proposed project.
7.1.3 Our field investigation indicates the site is underlain by undocumented fill overlying Old
Paralic Deposits. The undocumented fill is unsuitable in the present condition and will
require remedial grading where improvements are planned as discussed herein. We should
evaluate the actual extent of unsuitable soil removal in the field during the grading
operations.
7.1.4 We did not encounter groundwater during our field investigation to the maximum depth
explored of 12 feet. We anticipate that groundwater is present at depths greater than
50 feet. We do not expect groundwater to significantly impact project development as
presently proposed.
7 .1.5 The proposed development can be supported on conventional shallow or post-tensioned
foundations bearing in compacted fill materials.
7.1.6 We performed a storm water management investigation to help evaluate the potential for
infiltration on the property. Based on the infiltration rates measured during our field
investigation, we opine full infiltration on the property should be considered infeasible.
However, partial infiltration may be considered feasible within the Old Paralic Deposits as
discussed in Appendix C.
7.1 .7 Based on our review of the conceptual project plans, we opine the planned development
can be constructed in accordance with our recommendations provided herein. We do not
expect the planned development will destabilize or result in settlement of adjacent
properties.
Project No. G2 l 92-52-0 I -7 -January 17, 201 8
7.2 Excavation and Soil Characteristics
7.2.1 Excavation of the undocumented fill and Old Paralic Deposits should be possible with light
to moderate effort using conventional heavy-duty grading eq uipment.
7.2.2 The soil encountered in the field investigation is considered to be "non-expansive" to
"expansive" (expansion index [EI] of 20 or less or greater than 20, respectively) as defined
by 2016 California Building Code (CBC) Section I 803.5.3 based on our test results.
Table 7.2 presents soi l classifications based on the expansion index. We expect the existing
site materials possess a "very low" to "low" expansion potential (expansion index of 50 or
less) in accordance with ASTM D 4829.
TABLE 7.2
EXPANSION CLASSIFICATION BASED ON EXPANSION INDEX
Expansion Index (El) ASTM D 4829 Soil 2016 CBC
Expansion Classification Expansion Classification
0 -20 Very Low Non-Expansive
21-50 Low
51 -90 Medium
91 -130 High
Expansive
Greater Than 130 Very High
7.2.3 We performed laboratory tests on soil samples to evaluate the water-soluble sulfate content
(California Test No. 417) to generally evaluate the corrosion potential to structures in contact
with soil. Results from the laboratory water-soluble su lfate content tests indicate that the
materials at the locations tested possesses "SO" su lfate exposure to concrete structures as
defined by 2016 CBC Section 1904 and ACI 318-11 Sections 4.2 and 4.3. 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.
Appendi x B presents the results of the laboratory tests.
7.2.4 Geocon Incorporated does not practice in the field of corrosion engineering; therefore,
further evaluation by a corrosion engineer may be needed to incorporate the necessary
precautions to avoid premature corrosion of underground pipes and buried metal in direct
contact with the soils.
Project No. G2192-52-0 I -8 -January 17, 2018
7.3 Grading
7.3.1 The grading operations should be performed in accordance with the attached Recommended
Grading Specifications (Appendix D). Where the recommendations of thi s section conflict
with Appendix D, the recommendations of this section take precedence. We should observe
and test earthwork for proper compaction and moisture content.
7.3.2 A pre-construction meeting with the city inspector, owner, general contractor, civil
engineer and geotechnical engineer should be held at the site prior to the beginning of
grading and excavation operations. Special soil handling requirements can be discussed at
that time, if necessary.
7.3.3 We should observe the earthwork operations and test the compacted fill.
7.3.4 Grading of the site should commence with the demolition of existing structures, removal of
existing improvements, vegetation, and deleterious debris. Deleterious debris should be
exported from the site and should not be mixed with the fill. Existing underground
improvements within the proposed structure area that extend below the planned grading
limits should be removed and properly backfilled.
7.3 .5 The undocumented fill within the site boundaries should be removed to expose the
underlying Old Paralic Deposits. We should evaluate the actual extent of unsuitable soil
removals during the grading operations. Prior to fill soi l being placed, the existing ground
surface should be scarified, moisture conditioned as necessary, and compacted to a depth of
at least 12 inches.
7.3.6 To reduce the potential for differential settlement of the compacted fill, the residential
building pads with cut-fill transitions should be undercut at least 3 feet and replaced with
properly compacted fill. In addition, cut pads that expose the Old Paralic Deposits should
also be undercut at least 3 feet to faci litate future trenching and provide a more uniform
finish grade soil condition.
7.3.7 The site should then be brought to final subgrade elevations with fill compacted in layers.
In general, soil native to the site is suitable for use from a geotechnical engineering
standpoint as fill if relatively free from vegetation, debris and other deleterious material.
Layers of fill should be about 6 to 8 inches in loose thickness and no thicker than will allow
for adequate bonding and compaction. Fill, including backfill and scarified ground
surfaces, should be compacted to a dry density of at least 90 percent of the laboratory
maximum dry density near to slightly above optimum moisture content in accordance with
Project No. 02192-52-0 I -9 -January 17, 2018
ASTM Test Procedure D 1557. Fill materials placed below optimum moisture content may
require additional moisture conditioning prior to placing additional fill. The upper
12 inches of subgrade soil underlying pavement should be compacted to a dry density of at
least 95 percent of the laboratory maximum dry density near to slightly above optimum
moisture content shortly before paving operations.
7.3.8 Import fill (if necessary) should consist of granular materials with a "very low" to "low"
expansion potential (EI of 50 or less) free of deleterious material or stones larger than
3 inches and should be compacted as recommended above. Geocon Incorporated should be
notified of the import soil source and should perform laboratory testing of import soil prior
to its arrival at the site to determine its suitability as fill material.
7.4 Temporary Excavations
7.4.1 The recommendations included herein are provided for stable excavations. It is the
responsibility of the contractor to provide a safe excavation during the construction of the
proposed project.
7.4.2 Temporary excavations should be made in conformance with OSHA requirements.
Undocumented fill should be considered a Type C soil in accordance with OSHA
requirements. The Old Paralic Deposits and compacted fill materials can be considered a
Type B soil (Type C soil if seepage or groundwater is encountered). In general, special
shoring requirements will not be necessary if temporary excavations will be less than 4 feet
in height and raveling of the excavations does not occur. Temporary excavations greater
than 4 feet in height, however, should be sloped back at an appropriate inclination. These
excavations should not be allowed to become saturated or to dry out. Surcharge loads
should not be permitted to a distance equal to the height of the excavation from the top of
the excavation. The top of the excavation should be a minimum of 15 feet from the edge of
existing improvements. Excavations steeper than those recommended or closer than 15 feet
from an existing surface improvement should be shored in accordance with applicable
OSHA codes and regulations. Geocon can provide temporary shoring recommendations, if
necessary.
7.5 Seismic Design Criteria
7.5. l We used the computer program US. Seismic Design Maps, provided by the USGS.
Table 7 .5 .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 second. The building structures and improvements should be
Project No. G2192-52-0 I -IO -January 17, 2018
designed using a Site Class C. We evalu ated 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. The values presented
in Table 7.5.1 are for the risk-targeted maximum considered earthquake (MCER).
TABLE 7.5.1
2016 CBC SEISMIC DESIGN PARAMETERS
Parameter Value 2016 CBC Reference
Site Class C Section 1613 .3.2
MCER Ground Motion Spectral 1.127g Figure 1613.3.1(1) Response Acceleration -Class B (short), Ss
MCER Ground Motion Spectral 0.433g Figure 1613.3.1(2) Response Acceleration -Class B (I sec), S1
Site Coefficient, FA 1.000 Table 1613.3 .3(1)
Site Coefficient, Fv 1.367 Table 1613.3.3(2)
Site Class Modified MCER Spectral 1.127g Section 1613.3.3 (Eqn 16-37) Response Acceleration (short), SMs
Site Class Modified MCER Spectral 0.592g Section 1613.3.3 (Eqn 16-38) Response Acceleration (I sec), SM1
5% Damped Design Spectral 0.75 lg Section 1613.3.4 (Eqn 16-39) Response Acceleration (short), Sos
5% Damped Design Spectral 0.395g Section 1613.3.4 (Eqn 16-40) Response Acceleration (I sec), Soi
7.5.2 Table 7.5.2 presents additional seismic design parameters for projects located in Seismic
Design Categories of D through F in accordance with ASCE 7-1 0 for the mapped
maximum considered geometric mean (MCEG).
TABLE 7.5.2
2016 CBC SITE ACCELERATION DESIGN PARAMETERS
Parameter Value ASCE 7-10 Reference
Mapped MCE0 Peak Ground Acceleration, PGA 0.443g Figure 22-7
Site Coefficient, FPGA 1.000 Table 11.8-1
Site Class Modified MCEG 0.443g Section 11.8.3 (Eqn 11.8-1) Peak Ground Acceleration, PGAM
7.5.3 Conformance to the criteria in Tables 7.5.1 and 7.5.2 for seismic design does not constitute
any ki nd of guarantee or assurance that significant structural damage or gro und failure will
not occur if a large earthquake occurs. The primary goal of seismic design is to protect life,
not to avoid all damage, since such design may be economically prohibitive.
Project No. G2I92-52-01 -11 -January 17, 2018
7.6 Shallow Foundations
7.6.1 The foundation recommendations herein are for the proposed residential structures founded
in compacted fill. Foundations for the structure should consist of continuous strip footings
and/or isolated spread footings. Continuous footings should be at least 18 inches wide and
extend at least 18 inches below lowest adjacent pad grade. Isolated spread footings should
have a minimum width of 24 inches and should extend at least 18 inches below lowest
adjacent pad grade. Figure 3 presents a footing dimension detail depicting the depth to
lowest adjacent grade.
7.6.2 Steel reinforcement for continuous footings should consist of at least four No. 4 steel
reinforcing bars placed horizontally in the footings, two near the top and two near the
bottom. Steel reinforcement for the spread footings should be designed by the project
structural engineer. The minimum reinforcement recommended herein is based on soil
characteristics only (expansion index of 50 or less) and is not intended to replace
reinforcement required for structural considerations.
7.6.3 The recommended allowable bearing capac ity for foundations with minimum dimensions
described herein and bearing in properly compacted fill is 2,000 pound s per squ are foot
(psf). The values presented herein are for dead plus live loads and may be increased by
one-third when considering transient loads due to wind or seismic forces.
7.6.4 Total and differential settlement of the building founded on compacted fill materials 1s
expected to be less than ½-inch for 6-foot footings.
7.6.5 Where buildings or other improvements are planned near the top of a slope 3:1 (horizontal
to vertical) or steeper, special foundation and/or design considerations are recommended
due to the tendency for lateral soil movement to occur.
• Footings should be deepened such that the bottom outside edge of the footing is at
least 7 feet horizontally from the face of the slope.
• Although other improvements, which are relatively rigid or brittle, such as concrete
flatwork or masonry walls, may experience some distress if located near the top of
a slope, it is generally not economical to mitigate this potential. It may be possible,
however, to incorporate design measures which would permit some lateral so il
movement without causing extensive distress. Geocon Incorporated should be
consulted for specific recommendations.
7.6.6 We should observe the foundation excavations prior to the placement of reinforcing steel
and concrete to check that the exposed soil conditions are similar to those expected and that
Project No. 02192-52-0 I -12 -January 17, 2018
they have been extended to the appropriate bearing strata. Foundation modifications may
be required if unexpected soil conditions are encountered.
7.6.7 Geocon Incorporated shou ld be consulted to provide additional design parameters as
required by the structural engineer.
7.7 Concrete Slabs-on-Grade
7.7.1 Concrete slabs-on-grade for the structures should be at least 4 inches thick and reinforced
with No. 3 steel reinforcing bars at 24 inches on center in both horizontal directions.
7.7.2 Slabs that may receive moisture-sensitive floor coverings or may be used to store moisture-
sensitive materials should be underlain by a vapor retarder. The vapor retarder design
should be consistent with the guidelines presented in the American Concrete Institute's
(ACI) Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials
(ACI 302.2R-06). In addition, the membrane should be installed in accordance with
manufacturer's recommendations and ASTM requirements and installed in a manner that
prevents puncture. The vapor retarder used should be specified by the project architect or
developer based on the type of floor covering that wi ll be installed and if the structure will
possess a humidity controlled environment.
7.7.3 The bedding sand thickness should be detennined by the project foundation engineer,
architect, and/or developer. However, we should be contacted to provide recommendations
if the bedding sand is thicker than 6 inches. It is common to see 3 to 4 inches of sand below
the concrete slab-on-grade for 5-inch thick slabs in the southern California area. The
foundation design engineer should provide appropriate concrete mix design criteria and
curing measures to assure proper curing of the slab by reducing the potential for rapid
moisture loss and subsequent cracking and/or slab curl. We suggest that the foundation
design engineer present the concrete mix design and proper curing methods on the
foundation plans. It is critical that the foundation contractor understands and fo llows the
recommendations presented on the foundation plans.
7.7.4 Concrete slabs should be provided with adequate crack-control joints, construction joints
and/or expansion joints to reduce unsightly shrinkage cracking. The design of joints should
consider criteria of the American Concrete [nstitute (ACI) when establishing crack-control
spacing. Crack-control joints should be spaced at intervals no greater than 12 feet.
Additional steel reinforcing, concrete admixtures and/or closer crack control joint spacing
should be considered where concrete-exposed finished floors are planned.
Project No. 02192-52-01 -13 -January 17, 2018
7.7.5 The concrete slab-on-grade recommendations are based on soil support characteristics
only. The project structural engineer should evaluate the structural requirements of the
concrete slabs for supporting vehicle, equipment and storage loads.
7.7.6 The recommendations presented herein are intended to reduce the potential for cracking of
slabs and foundations as a result of differential movement. However, even with the
incorporation of the recommendations presented herein, foundations and slabs-on-grade
will still exhibit some cracking. The occurrence of concrete shrinkage cracks is
independent of the soil supporting characteristics. Their occurrence may be reduced and/or
controlled by limiting the slump of the concrete, the use of crack-control joints and proper
concrete placement and curing. Literature provided by the Portland Cement Association
(PCA) and American Concrete Institute (ACI) present recommendations for proper
concrete mix, construction, and curing practices, and should be incorporated into project
construction.
7.8 Post-Tensioned Foundation System Recommendations
7.8.1 As an alternative to the conventional foundation recommendations, consideration should be
given to the use of post-tensioned concrete slab and foundation systems for the support of
the proposed structures. The post-tensioned systems should be designed by a structural
engineer experienced in post-tensioned slab design and design criteria of the Post-
Tensioning Institute (PTI) DC 10.5-12 Standard Requirements for Design and Analysis of
Shallow Post-Tensioned Concrete Foundations on Expansive Soils or WRJ/CRSJ Design of
Slab-on-Ground Foundations, as required by the 2016 California Building Code (CBC
Section 1808.6.2). Although this procedure was developed for expansive soil conditions, it
can also be used to reduce the potential for foundation distress due to differential fill
settlement. The post-tensioned design should incorporate the geotechnical parameters
presented in Table 7.8. The parameters presented in Table 7.8 are based on the guidelines
presented in the PTI DC 10.5 design manual.
TABLE 7.8
POST-TENSIONED FOUNDATION SYSTEM DESIGN PARAMETERS
Post-Tensioning Institute (PTI) Value DCl0.5 Design Parameters
Thomthwaite Index -20
Equilibrium Suction 3.9
Edge Lift Moisture Variation Distance, eM (feet) 5.3
Edge Lift, YM (inches) 0.61
Center Lift Moisture Variation Distance, eM (feet) 9.0
Center Lift, YM (inches) 0.30
Project No. 02192-52-0 I -14 -January 17, 2018
7.8.2 Post-tensioned foundations may be designed for an allowable soil bearing pressure of 2,000
pounds per square foot (psf) (dead plus live load). This bearing pressure may be increased
by one-third for transient loads due to wind or seismic forces. The estimated maximum
total and differential settlement for the planned structures due to foundation loads is
½ inch.
7.8.3 The foundations for the post-tensioned slabs should be embedded in accordance with the
recommendations of the structural engineer. If a post-tensioned mat foundation system is
planned, the slab should possess a thickened edge with a minimum width of 12 inches and
extend below the clean sand or crushed rock layer.
7.8.4 Isolated footings, if present, should have the minimum embedment depth and width
recommended for conventional foundations. The use of isolated footings, which are located
beyond the perimeter of the building and support structural elements connected to the
building, are not recommended. Where this condition cannot be avoided, the isolated
footings should be connected to the building foundation system with grade beams.
7.8.5 Consideration should be given to using interior stiffening beams and connecting isolated
footings and/or increasing the slab thickness. In addition, consideration should be given to
connecting patio slabs, which exceed 5 feet in width, to the building foundation to reduce
the potential for future separation to occur.
7.8.6 If the structural engineer proposes a post-tensioned foundation design method other than
PTI, DC 10.5:
• The deflection criteria presented in Table 7.8 are still applicable.
• The width of the perimeter foundations should be at least 12 inches.
• The perimeter footing embedment depths should be at least 18 inches. The
embedment depths should be measured from the lowest adjacent pad grade.
7.8.7 Our experience indicates post-tensioned slabs may be susceptible to excessive edge lift,
regardless of the underlying soil conditions. Placing reinforcing steel at the bottom of the
perimeter footings and the interior stiffener beams may mitigate this potential. The
structural engineer should design the foundation system to reduce the potential of edge lift
occurring for the proposed structures.
7.8.8 During the construction of the post-tension foundation system, the concrete should be
placed monolithically. Under no circumstances should cold joints form between the
Project No. G2 I 92-52-0 I -15 -January 17, 20 18
footings/grade beams and the slab during the construction of the post-tension foundation
system unless designed by the structural engineer.
7.8.9 Special subgrade presaturation is not deemed necessary prior to placing concrete; however,
the exposed foundation and slab subgrade soil should be moisturized to maintain a moist
condition as would be expected in any such concrete placement. The slab underlayment
should be the same as previously discussed.
7.9 Concrete Flatwork
7.9.1 Exterior concrete flatwork not subject to vehicular traffic should be constructed in
accordance with the recommendations herein. Slab panels should be a minimum of
4 inches thick and, when in excess of 8 feet square, should be reinforced with
6 x 6 -W2.9/W2.9 (6 x 6 -6/6) welded wire mesh or No. 3 reinforcing bars spaced at least
18 inches center-to-center in both directions to reduce the potential for cracking. In
addition, concrete flatwork should be provided with crack control joints to reduce and/or
control shrinkage cracking. Crack control spacing should be determined by the project
structural engineer based upon the slab thickness and intended usage. Criteria of the
American Concrete Institute (ACI) should be taken into consideration when establishing
crack control spacing. Subgrade soil for exterior slabs not subjected to vehicle loads should
be compacted in accordance with criteria presented in the grading section prior to concrete
placement. Subgrade soil should be properly compacted and the moisture content of
subgrade soil should be checked prior to placing concrete.
7.9.2 Even with the incorporation of the recommendations within this report, the exterior
concrete flatwork has a likelihood of experiencing some uplift due to expansive soil
beneath grade; therefore, the steel reinforcement should overlap continuously in flatwork to
reduce the potential for vertical offsets within flatwork. Additionally, flatwork should be
structurally connected to the curbs, where possible, to reduce the potential for offsets
between the curbs and the flatwork.
7 .9 .3 Where exterior flatwork abuts the structure at entrant or exit points, the exterior slab should
be dowelled into the structure's foundation stemwall. This recommendation is intended to
reduce the potential for differential elevations that could result from differential settlement
or minor heave of the flatwork. Dowelling details should be designed by the project
structural engineer.
Project No. 02192-52-01 -16 -January 17, 2018
7.10
7.10.1
7.10.2
7.10.3
7.10.4
7.10.5
Retaining Walls
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 (pct). Where the backfill will be inclined at no steeper
than 2H: 1 V, 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 of 50 or less.
Unrestrained walls are those that are allowed to rotate more than 0.001H (where H equal s
the height of the retaining portion of the wall) at the top of the wall. Where walls are
restrained from movement at the top (at-rest condition), an additional uniform pressure of
7H psf should be added to the active soil pressure for walls 8 feet or less. For retaining
walls subject to vehicular loads within a horizontal distance equal to two-thirds the wall
height, a surcharge equivalent to 2 feet of fill soil should be added.
The structural engineer should determine the seismic design category for the project. If the
project possesses a seismic design category of D, E, or F, the proposed retaining walls
should be designed with seismic lateral pressure. A seismic load of 16H psf should be used
for design of walls that support more than 6 feet of backfill 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. We used the
peak site acceleration, PGAM, of0.443g calculated from ASCE 7-10 Section 11.8.3.
The retaining walls may be designed using either the active and restrained (at-rest) loading
condition or the active and seismic loading condition as suggested by the structural
engineer. Typically, it appears the design of the restrained condition for retaining wall
loading may be adequate for the seismic design of the retaining walls. However, the active
earth pressure combined with the seismic design load should be reviewed and also
considered in the design of the retaining walls.
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 proj ect architect. The
use of drainage openings through th e 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 recommendations herein assume a properly compacted free-
draining backfill material (El of 50 or less) with no hydrostatic forces or imposed surcharge
load. Figure 4 presents a typical retaining wall drain detail. If conditions different than
Project No. G2 I 92-52-0 I -17 -January 17, 2018
7.10.6
7.10.7
7.10.8
7.10.9
7.11
7.11.1
those described are expected, or if specific drainage details are desired, Geocon
Incorporated should be contacted for additional recommendations.
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.
In general, wall foundations having a minimum depth and width of l foot may be designed
for an allowable soil bearing pressure of 2,000 psf. The proximity of the foundation to the
top of a slope steeper than 3: 1 could impact the allowable soil bearing pressure. Therefore,
retaining wall foundations should be deepened such that the bottom outside edge of the
footing is at least 7 feet horizontally from the face of the slope.
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 retaining walls and improvements above the retaining walls
should be designed to incorporate an appropriate amount of lateral deflection as determined
by the structural engineer.
The recommendations presented herein are generally applicable to the design of rigid
concrete or masonry retaining walls having a maximum height of 8 feet. In the event that
walls higher than 8 feet or other types of walls (such as mechanically stabilized earth
[MSE] walls, soil nail walls, or soldier pile walls) are planned, Geocon Incorporated should
be consulted for additional recommendations.
Lateral Loading
To resist lateral loads, a passive pressure exerted by an equivalent fluid weight of
350 pounds per cubic foot (pct) should be used for the design of footings or shear keys
poured neat in compacted fill. The passive pressure assumes a horizontal surface extending
at least 5 feet, or three times the surface generating the passive pressure, whichever is
greater. The upper 12 inches of material in areas not protected by floor slabs or pavement
should not be included in design for passive resistance.
Project No. G2 I 92-52-0 I -18 -January 17, 2018
7 .11.2
7 .11.3
7.12
7.12.1
7.12.2
7.12.3
If friction is to be used to resist lateral loads, an al lowable coefficient of friction between
soil and concrete of 0.35 should be used for design. The friction coefficient may be reduced
to 0.2 to 0.25 depending on the vapor barrier or waterproofing material used for
construction in accordance with the manufacturer's recommendations
The passive and frictional resistant loads can be combined for design purposes. The lateral
passive pressures may be increased by one-third when considering transient loads due to
wind or seismic forces.
Preliminary Pavement Recommendations
We calculated the flexible pavement sections in general conformance with the Ca/trans
Method of Flexible Pavement Design (Highway Design Manual, Section 608.4) using an
estimated Traffic Index (TI) of 5.0 and 6.0 for local and coll ector streets, respectively. The
project civil engineer and owner should rev iew the pavement designations to determine
appropriate locations for pavement thickness. The final pavement sections for the parking
lot should be based on the R-Value of the subgrade soil encountered at final subgrade
elevation. Based on the results of our R-Value testing of the subgrade soils, we assumed an
R-Value of 44 and 78 for the subgrade soi l and base materials, respectively, for the
purposes of this preliminary analysis. Table 7 .12.1 presents the preliminary flexible
pavement sections.
TABLE 7.12.1
PRELIMINARY FLEXIBLE PAVEMENT SECTION
Assumed Assumed Asphalt Cla ss 2
Location Traffic Index Subgrade Concrete* Aggregate
R-Value (inches) Base* (inches)
Local Street 5.0 44 4 4
Coll ector Street 6.0 44 4 6
*Per City of Carlsbad Engineering Standards (2016)
The subgrade soils for pavement areas should be compacted to a dry density of at least
95 percent of the laboratory maximum dry density near to slightly above the optimum
moisture content. The depth of subgrade compaction should be approximately 12 inches.
Class 2 aggregate base should conform to Section 26-l-02B of the Standard Specifications
for The State of California Department of Transportation (Ca/trans) and should be
compacted to a min imum of 95 percent of the maximum dry density at near optimum
Project No. G2192-52-0 I -19 -January 17, 2018
7.12.4
7.12.5
7.12.6
7.12.7
7.12.8
moisture content. The asphalt concrete should conform to Section 203-6 of the Standard
Specifications for Public Works Construction (Green book).
The base thickness can be reduced if a reinforcement geogrid is used during the installation
of the pavement. Geocon should be contact for additional recommendations, if requested.
A rigid Portland cement concrete (PCC) pavement section should be placed in driveway
entrance aprons. We calculated the rigid pavement section in general conformance with the
procedure recommended by the American Concrete Institute report ACI 330R-08 Guide for
Design and Construction of Concrete Parking Lots using the parameters presented in
Table 7.12.2.
TABLE 7.12.2
RIGID PAVEMENT DESIGN PARAMETERS
Design Parameter Design Value
Modulus of subgrade reaction, k 100 pci
Modulus ofrupture for concrete, MR 500 psi
Traffic Category, TC A and C
Average daily truck traffic, ADTT 1 and 100
Based on the criteria presented herein, the PCC pavement sections should have a minimum
thickness as presented in Table 7.12.3 .
TABLE 7.12.3
RIGID PAVEMENT RECOMMENDATIONS
Location Portland Cement Concrete (inches)
Driveways/ Automobile Parking Areas (TC=A) 5.0
Heavy Truck and Fire Lane Areas (TC=C) 7.0
The PCC pavement should be placed over subgrade soil that is compacted to a dry density
of at least 95 percent of the laboratory maximum dry density near to slightly above
optimum moisture content. This pavement section is based on a minimum concrete
compressive strength of approximately 3,000 psi (pounds per square inch).
A thickened edge or integral curb should be constructed on the outside of concrete slabs
subjected to wheel loads. The thickened edge should be 1.2 times the slab thickness or a
Project No. 02192-52-01 -20 -January 17, 20 18
7.12.9
minimum thickness of 2 inches, whichever results in a thicker edge, and taper back to the
recommended slab thickness 4 feet behind the face of the slab ( e.g., a 7-inch-thick slab
would have a 9-inch-thick edge). Reinforcing steel will not be necessary within the
concrete for geotechnical purposes with the possible exception of dowels at construction
joints as discussed herein.
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 shou ld not exceed 30 times the slab thickness with a maximum
spacing of 12.5 feet for the 5-inch and 15 feet for 6-inch or thicker slabs and should be
sealed with an appropriate sealant to prevent the migration of water through the control
joint to the subgrade materials. The depth of the crack-control joints should be determined
by the referenced ACI report. The depth of the crack-control joints should be at least ¼ of
the slab thickness when using a conventional saw, or at least 1 inch when using early-entry
saws on slabs 9 inches or less in thickness, as determined by the referenced ACI report
discussed in the pavement section herein. Cuts at least ¼ inch wide are required for sealed
joints, and a ¾ inch wide cut is commonly recommended. A na1Tow joint width of 1/10 to 1/s
inch-wide is common for unsealed joints.
7.12.10 To provide load transfer between adjacent pavement slab sections, a butt-type construction
joint should be constructed. The butt-type joint should be thickened by at least 20 percent
at the edge and taper back at least 4 feet from the face of the slab. As an alternative to the
butt-type construction joint, dowelling can be used between construction joints for
pavements of 7 inches or thicker. As discussed in the referenced ACI guide, dowels should
consist of smooth, I-inch-diameter reinforcing steel 14 inches long embedded a minimum
of 6 inches into the slab on either side of the construction joint. Dowels should be located
at the midpoint of the slab, spaced at 12 inches on center and lubricated to allow joint
movement while still transferring loads. In addition, tie bars should be installed at the as
recommended in Section 3.8.3 of the referenced ACI guide. The structural engineer should
provide other alternative recommendations for load transfer.
7.12.11 Concrete curb/gutter should be placed on soil subgrade compacted to a dry density of at
least 90 percent of the laboratory maximum dry density near to slightly above optimum
moisture content. Cross-gutters should be placed on subgrade soil compacted to a dry
density of at least 95 percent of the laboratory maximum dry density near to slightly above
optimum moisture content. Base materials should not be placed below the curb/gutter,
cross-gutters, or sidewalk so water is not able to migrate from the adjacent parkways to the
pavement sections. Where flatwork is located directly adjacent to the curb/gutter, the
Project No. 02192-52-0 I -21 -January 17, 2018
7.13
7.13.1
7.13.2
7.13.3
7.13.4
7.14
7.14.1
concrete flatwork should be structurally connected to the curbs to help reduce the potential
for offsets between the curbs and the flatwork.
Site Drainage and Moisture Protection
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 1804.3 or other applicable
standards. In addition, surface drainage should be directed away from the top of slopes into
swales or other controlled drainage devices. Roof and pavement drainage should be
directed into conduits that carry runoff away from the proposed structure. Appendix C
presents the results of the storm water management investigation.
The performance of pavements 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. If planter islands are proposed, the
perimeter curb should extend at least 12 inches below proposed subgrade elevations. In
addition, the surface drainage within the planter should be such that ponding will not occur.
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.
Landscaping planters adjacent to paved areas are not recommended due to the potential for
surface or irrigation water to infiltrate the pavement's subgrade and base course. Area
drains to collect excess irrigation water and transmit it to drainage structures or impervious
above-grade planter boxes can be used. In addition, where landscaping is planned adjacent
to the pavement, construction of a cutoff wall along the edge of the pavement that extends
at least 6 inches below the bottom of the base material should be considered.
Grading, Improvement and Foundation Plan Review
Geocon Incorporated should review the final grading, improvement and foundation plans
prior to finalization to check their compliance with the recommendations of this report and
evaluate the need for additional comments, recommendations, and/or analyses.
Project No. 02192-52-0 I -22 -January 17, 2018
LIMITATIONS AND UNIFORMITY OF CONDITIONS
1. The firm that performed the geotechni cal investigation for the project should be retained to
provide testing and observation services during construction to provide continuity of
geotechnical interpretation and to check that the recommendations presented for geotechnical
aspects of site development are incorporated during site grading, construction of
improvements, and excavation of foundations. If another geotechnical firm is selected to
perform the testing and observation services during construction operations, that firm should
prepare a letter indicating their intent to assume the responsibilities of project geotechnical
engineer of record. A copy of the letter should be provided to the regulatory agency for their
records. In addition, that firm should provide revised recommendations concerning the
geotechnical aspects of the proposed development, or a written acknowledgement of their
concurrence with the recommendations presented in our report. They should also perform
additional analyses deemed necessary to assume the role of Geotechnical Engineer of Record.
2. The recommendations of this report pertain only to the site investigated and are based upon
the assumption that the soil conditions do not deviate from those disclosed in the
investigation. If any variations or undesirable conditions are encountered during construction,
or if the proposed construction wi ll differ from that anticipated herein, Geocon Incorporated
should be notified so that supplemental recommendations can be given. The evaluation or
identification of the potential presence of hazardous or corrosive materials was not part of the
scope of services provided by Geocon Incorporated.
3. This report is issued with the understanding that it is the responsibility of the owner or his
representative to ensure that the information and recommendations contained herein are
brought to the attention of the architect and engineer for the project and incorporated into the
plans, and the necessary steps are taken to see that the contractor and subcontractors carry out
such recommendations in the field.
4. The findings of this report are valid as of the present date. However, changes in the
conditions of a property can occur with the passage of time, whether they be due to natural
processes or the works of man on this or adjacent properties. In addition, changes in
applicable or appropriate standards may occur, whether they result from legislation or the
broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly
or partially by changes outside our control. Therefore, this report is subject to review and
should not be relied upon after a period of three years.
Project No. 02192-52-01 January 17, 201 8
THE GEOGRAPHICAL INFORMATION MADE AVAILABLE FOR DISPLAY WAS PROVIDED BY GOOGLE EARTH,
SUBJECT TO A LICENSING AGREEMENT. THE INFORMATION IS FOR ILLUSTRATIVE PURPOSES ONLY; IT IS
NOT INTENDED FOR CLIENT'S USE OR RELIANCE AND SHALL NOT BE REPRODUCED BY CLIENT. CLIENT
SHALL INDEMNIFY, DEFEND AND HOLD HARMLESS GEOCON FROM ANY LIABILITY INCURRED AS A RESULT
OF SUCH USE OR RELIANCE BY CLIENT.
VICINITY MAP
G OCON
INCORPORATED
GEOTECHNICAL ■ ENVIRONMENTAL ■ MATERIALS
6960 FLANDERS DRIVE-SAN DIEGO, CALIFORNIA 921 21-297 4
PHONE 858 558-6900 -FAX 858 558-6159
t
N
NO SCALE
1534 MAGNOLIA AVENUE
CARLSBAD, CALIFORNIA
ML /CW DSK/GTYPD DATE 01 -17 -2018 I PROJECT NO.G2192 -52 -01 I FIG. 1
Plotted:01/16/2018 3:15PM I By:JONATHAN WILKINS [ FIie locatlon:Y:\PROJECTS\G2192-52-01 1534 Magnolia Ave\DETAILS\G2192-52-01_Vlclnlty Map.dwg
I
I
,:
;. ,~
,:
THE GEOGRAPHICAL INFORMATION MADE AVAILABLE FOR DISPLAY WAS PROVIDED BY GOOGLE EARTH,
SUBJECT TO A LICENSING AGREEMENT. THE INFORMATION IS FOR ILLUSTRATIVE PURPOSES ONLY; IT IS
NOT INTENDED FOR CLIENrS USE OR RELIANCE AND SHALL NOT BE REPRODUCED BY CLIENT. CLIENT
SHALL INDEMNIFY, DEFEND AND HOLD HARMLESS GEOCON FROM ANY LIABILITY INCURRED AS A RESULT
OF SUCH USE OR RELIANCE BY CLIENT.
y -
1 j;
0 ' ' ,~ ,. 1/. I I., I
,,
/v,' D
1534 MAGNOLIA AVENUE
CARSBAD, CALIFORNIA
o· 60' 120·
SCALE 1•= 60' (On 11x17)
GEOCON LEGEND
Qudf ........ uNDocuMENTED FILL
Qop ........ OLD PARALIC DEPOSITS
T-9....._. ,....... ........ APPROX. LOCATION OF TRENCH
(P-2) ........ APPROX. LOCATION OF PERCOLATION TEST
G::) ........ APPROX. THICKNESS OF UNDOCUMENTED FILL
GEOLOGIC MAP
GEOCON
INCORPORATED
u. ~
GEOTECHNICAL ■ ENVIRONMENTAL ■ MATERIALS
6960 FLANDERS DRIVE -SAN DIEGO, CALIFORNIA 92121 • 297 4
PHONE 858 558-6900 -FAX 858 558-6159
PROJECT NO. G2 l 92 -52 -01
FIGURE 2
DATE O 1 -1 7 -201 8
Plotted:01118/2018 1:16PM I By:JONATHAN WILKINS I FIie Locatloo:Y:IPROJECTSIG2192-52-01 1534 Magnolia Ave\SHEETSIG2192-52-01 Geologic map.dwg
PROPOSED
GRADE
NOTE:
WATER PROOFING
PER ARCHITECT
213 H
GROUND SURFACE \
RETAINING
WALL
2/3 H
DRAINAGE PANEL
(MIRADRAIN 6000
OR EQUIVALENT)
DRAIN SHOULD BE UNIFORMLY SLOPED TO GRAVITY OUTLET
OR TO A SUMP WHERE WATER CAN BE REMOVED BY PUMPING
MIRAFI 140N FILTER FABRIC
(OR EQUIVALENT)
OPEN GRADED
1" MAX. AGGREGATE
4" DIA. PERFORATED SCHEDULE
40 PVC PIPE EXTENDED TO
APPROVED OUTLET
RETAINING
WALL
PROPOSED
GRADE\
2/3 H
GROUND SURFACE
WATER PROOFING
PER ARCHITECT
DRAINAGE PANEL
(MIRADRAIN 6000
OR EQUIVALENT)
/
4" DIA. SCHEDULE 40
PERFORATED PVC PIPE
OR TOTAL DRAIN
EXTENDED TO
APPROVED OUTLET
NO SCALE
TYPICAL RETAINING WALL DRAIN DETAIL
GEOCON
INCORPORAT ED
GEOTECHNICAL ■ ENVIRONMENTAL ■ MATERIALS
6960 FLANDERS DRIVE -SAN DIEGO, CALIFORNIA 92121 -297 4
PHONE 858 558-6900 -FAX 858 558-6159
ML /CW I I DSK/GTYPD
1534 MAGNOLIA AVENUE
CARLSBAD, CALIFORNIA
DATE 01 -17 -2018 I PROJECT NO.G2192 -52 -01 I FIG. 4
Plotted:01/16/2018 4:07PM I By:JONATHAN WILKINS I FIie Locatlon:Y:IPROJECTSIG2192-52-01 1534 Magnolia Ave\DETAILS\Typlcal Retaining Wall Drainage Detail (RWDD7A).dwg
APPENDIX
APPENDIX A
FIELD INVESTIGATION
We performed our fie ld investigation on September 27, 2017, that consisted of a visual site
reconnaissance, excavating 9 exploratory trenches using a rubber-tire backhoe and conducting 2
infiltration tests. The approximate locations of the trenches and infiltration tests are shown on the
Geologic Map, Figure 2. As trenching proceeded, we logged and sampled the soi l and geologic
conditions encountered. Trench logs and an explanation of the geologic units encountered are
presented on figures fol lowing the text in this appendix. We located the trenches in the field using
existing reference points. Therefore, actual exploration locations may deviate sli ghtly.
We visually classified and logged the soil encountered in the excavations in general accordance with
American Society for Testing and Materials (ASTM) practice for Description and Identification of
Soils (Visual Manual Procedure D 2488).
Project No. G2 I 92-52-0 I January 17, 2018
PROJECT NO. G2192-52-01
DEPTH
IN
FEET
0
2
4
6
8
SAMPLE
NO.
Tl-I
T l-2
Figure A-1,
>-(9
0 -' 0 I I-::;
er: w
i 0 z :::i
0 er: (9
SOIL
CLASS
(USCS)
SM
SM
CL
SC
TRENCH T 1
ELEV. (MSL.) DATE COMPLETED 09-27-2017 ----
EQUIPMENT BACKHOE W/2' BUCKET BY: K. HAASE
MATERIAL DESCRIPTION
UNDOCUMENTED FILL (Qudl)
Loose, d1y Silty, fine to medium SAND: some roots
OLD PARALIC DEPOSITS (Qop2-4)
Medium dense, damp, light reddish brown, Si lty, fine to medium SAND
Dense, moist, olive-brown, fine Sandy, CLAY; iron staining
Medium dense, moist, reddish brown to olive brown, Clayey, fine to medium
SAND; iron staining
-Becomes denser
TRENCH TERMINATED AT 9 FEET
No groundwater encountered
Log of Trench T 1, Page 1 of 1
~ u.i--:-ZLL wc_j 0 . >-~ er: 0
w ~ er:~
:::i I-I-z C/Jw -1-0 z ~o (.)
G2192-52-01.GPJ
SAMPLE SYMBOLS □ ... SAMPLING UNSUCCESSFUL I] ... STANDARD PENETRATION TEST ■ ... DRIVE SAMPLE (UNDISTURBED)
~ ... DISTURBED OR BAG SAMPLE ~ ... CHUNK SAMPLE y_ ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
GEOCON
PROJECT NO. G2192-52-01
Cl'.'. TRENCH T 2 Zw~ ~ w~ >-w Qui-: (9 I-u5---:-Cl'.'.~ DEPTH <l'. SOIL I-Z LL ::J I-0 ~ ~~ui ZlL
IN SAMPLE _J w · I-z
0 0 CLASS ELEV. (MSL.) t-en~ 0 C! en w
NO. z DATE COMPLETED 09-27-2017 -I-FEET I w-o >-e:. Oz I-::J (USCS) Zen-' ::; 0 W WC!l Cl'.'. ~o
Cl'.'. EQUIPMENT BACKHOE W/2' BUCKET BY:K.HAASE Cl..o::~ 0 u
(9
MATERIAL DESCRIPTION -0
!t:l
SM UNDOCUMENTED FILL (Qudf)
Loose, dry, light brown, Silty, fine SAND
---
.-I· -t.-l-
·:::.i-:.:;.::r SM OLD PARALIC DEPOSITS (Qop2-4)
-2 -~ Medium dense, damp, brown, Silty, fine SAND -
----------------------------------------------------
· .. ·. CL Dense, moist, olive brown, fine Sandy, CLAY --~ -
-4 -~ ._ -----~---------------------------------~---1---------
'./ SC Dense, moist, reddish brown, Clayey, fine to medium SAND 1(/y.
--Ji? t--✓/?--✓./~ . . ).
-6 ?3;
TRENCH TERMINATED AT 6 FEET
No groundwater encountered
Figure A-2, G2192-52-01.GPJ
Log of Trench T 2, Page 1 of 1
SAMPLE SYMBOLS □ ... SAMPLING UNSUCCESSFUL
~ ... DISTURBED OR BAG SAMPLE
II ... STANDARD PENETRATION TEST
liiiiJ ... CHUNK SAMPLE
■ ... DRIVE SAMPLE (UNDISTURBED)
.:f. ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
GEOCON
PROJECT NO. G2192-52-01
DEPTH
IN
FEET
0
2
4
6
SAMPLE
NO.
T3-l
Figure A-3,
>-0 0 ....J 0 I f--::::;
_.-( l
0:: w
i 0 z :J 0 0::
(9
SOIL
CLASS
(USCS)
SM
SM
SM
CL
TRENCH T 3
ELEV. (MSL.) __ _ DATE COMPLETED 09-27-2017
EQUIPMENT BACKHOE W/2' BUCKET
MATERIAL DESCRIPTION
UN DOCUMENTED FILL (Qudl)
Loose, dry, brown, Silty, fine SAND
OLD PARALIC DEPOSITS (Qop2-4)
BY: K.HAASE
Medium dense, damp, reddish to yellowish brown, Silty, fine to medium
SAND
Medium dense, moist, brown, Silty, fine to medium SAND
Dense, wet, dark reddish brown, fine Sandy, CLAY
TRENCH TERMINATED AT 6 FEET
No groundwater encountered
Log of Trench T 3, Page 1 of 1
w ~ o::~
:J f--f--z C/Jw -f--Oz ::::eo u
G2192-52-01.GPJ
SAMPLE SYMBOLS □ ... SAMPLING UNSUCCESSFUL I] ... STANDARD PENETRATION TEST ■ ... DRIVE SAMPLE (UNDISTURBED)
~ ... DISTURBED OR BAG SAMPLE liiiJ ... CHUNK SAMPLE _y_ ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
GEOCON
PROJECT NO. G2192-52-01
DEPTH
IN
FEET
-0
-2 -
~ 4 -
t--
t-6
SAMPLE
NO.
T4-l
>-('.)
0 __J
0 I I-::;
.-·.f·t.--i,: :-.r--r -1:·
..
•. .
-... .. . .
•. .
... -·.·:.
0:: L!J
i 0 z ::J 0 0:: ('.)
~-w-~ ~ 14
SOIL
CLASS
(USCS)
SM
SM
CL
'
TRENCH T 4
ELEV. (MSL.) __ _ DATE COMPLETED 09-27-2017
EQUIPMENT BACKHOE W/2' BUCKET
MATERIAL DESCRIPTION
UNDOCUMENTED FILL (Qudf)
Loose, dry, light brown, Silty, fine SAND
OLD PARALIC DEPOSITS (Qop2-4)
BY: K. HAASE
Medium dense, damp, light reddish brown, fine to coarse SAND
Dense, moist, olive brown to reddish brown, fine Sandy, CLAY
Zw~ ~ Qui-: 1-ZlL Cf)--:,
~~(/) Z LL Wu I-Cf) s: 0 . w-o >-~ ZCfJ--' wwcn 0:: o..O::~ 0
I-
---~---------------------------------~-------SC Dense, moist, olive brown to reddish brown, fine Sandy, CLAY
TRENCH TERMINATED AT 6 FEET
No groundwater encountered
t-
LU ~ o::~ ::J I-I-z Cf) L!J -I-Oz ~o u
Figure A-4, G2192-52-01.GPJ
Log of Trench T 4, Page 1 of 1
SAMPLE SYMBOLS □ ... SAMPLING UNSUCCESSFUL
~ ... DISTURBED OR BAG SAMPLE
I] ... STANDARD PENETRATION TEST
ii ... CHUNK SAMPLE
■ ... DRIVE SAMPLE (UNDISTURBED)
Y, ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
GEOCON
PROJECT NO. G2192-52-01
DEPTH
IN
FEET
0
2
4
6
8
10
12
SAMPLE
NO.
>-('.)
0 -' 0 I I-:::;
!!Tl
:---i ·-1 :·r
t·r:·i-:-:r
---i·.J_-.i··
:j';/ : . _--;<:
a:: w i 0 z
::i 0 a:: ('.)
SOIL
CLASS
(USCS)
SM
SM
SC
TRENCH T 5
ELEV. (MSL.) __ _ DATE COMPLETED 09-27-2017
EQUIPMENT BACKHOE W/2' BUCKET
MATERIAL DESCRIPTION
UNDOCUMENTED FILL (Qudt)
Loose, dry, light brown, Silty, fine SAND
OLD PARALIC DEPOSITS (Qop2-4)
BY: K. HAASE
Medium dense, moist, dark brown, Silty fine to medium SAND
-Becomes brown
-Becomes dense
Dense, moist, olive gray to reddish brown, Clayey fine to coarse SAND; iron
staining
TRENCH TERMINATED AT 12 FEET
No groundwater encountered
Zw~ f w ~ Qui-: f-Z LL (/)--:-a::~
c'i~ui Z LL ::i f-w . f-z
f-(/) s: 0(.) (/) w
-f-w -o >-~ Oz z (/)-' w WaJ a:: '.20 (La::~ 0 u
Figure A-5, G2192-52-01.GPJ
Log of Trench T 5, Page 1 of 1
SAMPLE SYMBOLS □ ... SAMPLING UNSUCCESSFUL
~ ... DISTURBED OR BAG SAMPLE
IJ ... STANDARD PENETRATION TEST
liiiiJ ... CHUNK SAMPLE
■ ... DRIVE SAMPLE (UNDISTURBED)
y_ ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
GEOCON
PROJECT NO. G2192-52-01
Cl'. TRENCH T 6 Zw~ ~ >-w Qui-: w "#.
(.'.) f-Cl)---:-o::-DEPTH <{ SOIL ~~~ ::, f-0 s: ZlL
IN SAMPLE ....J Cl'. f-Cl) wc_j f-z
0 0 CLASS ELEV. (MSL.) f-Cl) s: C/Jw
NO. z DATE COMPLETED 09-27-2017 O· -f-FEET I w-o >-~ Oz f-::, (USCS) ZC/J....J Cl'. ~o :i 0 wwco
Cl'. EQUIPMENT BACKHOE W/2' BUCKET BY: K. HAASE a..0::-0 u
(.'.)
MATERIAL DESCRIPTION -0 ).:-:r:r SM UNDOCUMENTED FILL (Qudf)
::·.14:·1 Loose, dry, light brown, Silty, fine SAND
--i,...:.1 :.J.. I------1-----------------------------------t----~-------J ·l SM Loose, damp, light reddish brown, Silty fine SAND; little gravel; deleterious
J.1 ·1 material
-2 -:f (f -
.l -l
l ~ ·1 --.---r-t --y SM OLD PARALIC DEPOSITS (Qop2-4)
it! Medium dense, moist, dark reddish brown, Silty, fine to medium SAND
-4 --:---(i:·r
--ttt -
·--(1 :·r
-6 -. ·-r ·. t-
::::.:::::_(_:·:t::
-Becomes dark brown
-----(1 :·r t-
!II -Becomes denser, finer grained
-8 -t-~---•tJ e----------------------------------------f.-----------~/7 SC Dense, moist, reddish brown, Clayey, fine to medium SAND
---t;.? v/7
t-10 ":.":;,.··.-:·
TRENCH TER.MJNATED AT IO FEET
No groundwater encountered
Figure A-6, G2192-52-01.GPJ
Log of Trench T 6, Page 1 of 1
SAMPLE SYMBOLS □ ... SAMPLING UNSUCCESSFUL
~ ... DISTURBED OR BAG SAMPLE
I] ... STANDARD PENETRATION TEST
iii;! ... CHUNK SAMPLE
■ ... DRIVE SAMPLE (UNDISTURBED)
y_ ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
GEOCON
PROJECT NO. G2192-52-01
DEPTH
IN
FEET
0
2
4
SAMPLE
NO.
T7-l
>-(.'.)
0 ....J
0 I I-::;
0:: w
i 0 z :J 0 0:: (.'.)
SOIL
CLASS
(USCS)
SM
SM
TRENCH T 7
ELEV. (MSL.) ___ DATE COMPLETED 09-27-2017
EQUIPMENT BACKHOE W/2' BUCKET BY:K.HAASE
MATERIAL DESCRIPTION
UNDOCUMENTED FILL (Qudt)
Loose, dry, Light brown, Silty, fine SAND; roots
OLD PARALIC DEPOSITS (Qop2-4)
Medium dense, damp, light reddish brown, Silty, fine to medium SAND
-Becomes dense
TRENCH TERMlNATED AT 5 FEET
No groundwater encountered
Zw ~ ~ w ~ Qui-: 1-Z u.. Cl)--:-o::-
ri~ui zu.. :J I-
Wc.,j I-z
I-Cl)~ Cl) w O · -I-w-o >-e:. Oz ZCl)....J
WW CD 0:: ~o 11.0::-0 u
Figure A-7, G2192-52-01.GPJ
Log of Trench T 7, Page 1 of 1
SAMPLE SYMBOLS □ ... SAMPLING UNSUCCESSFUL
~ ... DISTURBED OR BAG SAMPLE
I] .. STANDARD PENETRATION TEST
~ ... CHUNK SAMPLE
■ ... DRIVE SAMPLE (UNDISTURBED)
y_ ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
GEOCON
PROJECT NO. G2192-52-01
cc TRENCH T 8 Zw~ /: >-w Qui-: w ~ I-DEPTH G <: SOIL 1-Z U.. ui--:-cc~
0 ~ ~;::en zu.. ::, I-
IN SAMPLE ....J w . I-z
0 0 CLASS ELEV. (MSL.) DATE COMPLETED 09-27-2017 1-C/J~ DC> (/) w
NO. I z w-o >-e:. -I-FEET I-::, (USCS) zC/J....J oz
::::; 0 w w cn cc ~o
cc EQUIPMENT BACKHOE W/2' BUCKET BY: K. HAASE o..cc~ 0 u
G
MATERIAL DESCRIPTION -0 ----r-1-r SM UNDOCUMENTED FILL (Qudt)
:J:::t:r Loose, dry, brown, Silty, ftne SAND; roots
--ill SM OLD PARALIC DEPOSITS (Qop2-4)
Medium dense, damp, light yellowish brown, Silty, fine SAND
-2 --
:---r-f:·-y ·-·-r · --:_:_j:.-:(J:_: -
--r----r \f:}:j:: -Becomes dense, moist, light reddish brown -4 TRENCH TERMINATED AT 4 FEET
No groundwater encountered
Figure A-8, G2192-52-01.GPJ
Log of Trench T 8, Page 1 of 1
SAMPLE SYMBOLS (;J ... SAMPLING UNSUCCESSFUL
~ ... DISTURBED OR BAG SAMPLE
IJ ... STANDARD PENETRATION TEST
liiiJ ... CHUNK SAMPLE
■ ... DRIVE SAMPLE (UNDISTURBED)
y_ ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
GEOCON
PROJECT NO. G2192-52-01
DEPTH
IN
FEET
0
2
4
SAMPLE
NO.
>-(.'.)
0 --' 0 I I-::;
Cl'. w i 0 z
::J 0 Cl'.
(.'.)
SOIL
CLASS
(USCS)
SM
SM
TRENCH T 9
ELEV. (MSL.) __ _ DATE COMPLETED 09-27-2017
EQUIPMENT BACKHOE W/2' BUCKET
MATERIAL DESCRIPTION
UNDOCUMENTED FILL (Qudl)
Loose, dry, brown, Silty, fine SAND; roots
BY: K. HAASE
OLD PARALIC DEPOSITS (Qop2)
Dense, damp, light reddish to yellowish brown, Silty fine to medium SAND
TRENCH TERMINATED AT 4 FEET
No groundwater encountered
Zw~ ~ w ~ Qu....,:
I-Z LL (/) ,--:-Cl'.~
~~iii Z LL ::J I-w . I-z
I-(/) 3:: 0(.) (/)w -I-w-o >-e:.. oz Z(J)--' wwoo Cl'. ~o Cl.a::~ 0 u
Figure A-9, G2192-52-01.GPJ
Log of Trench T 9, Page 1 of 1
SAMPLE SYMBOLS □ .. SAMPLING UNSUCCESSFUL
~ ... DISTURBED OR BAG SAMPLE
I] ... STANDARD PENETRATION TEST ■ ... DRIVE SAMPLE (UNDISTURBED)
~ ... CHUNK SAMPLE Y, ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE DATE INDICATED. IT
IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
GEOCON
APPENDIX
APPENDIX B
LABORATORY TESTING
We performed laboratory tests in accordance with generally accepted test methods of the American
Society for Testing and Materials (ASTM) or other suggested procedures. We selected samples to test
for maximum density and optimum moisture content, direct shear, expansion potential, water-soluble
sulfate content, R-Value and gradation. The results of our laboratory tests are summarized on Tables B-1
through B-V, Figure B-1 and on the trench logs in Appendix A.
Sample
No.
Tl-1
T7-l
Sample No.
Tl-1 2
T7-1 2
TABLE 8-1
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY AND
OPTIMUM MOISTURE CONTENT TEST RESULTS
ASTM D 1557
Description (Geologic Unit) Maximum Dry
Density (pct)
Light reddish brown, Silty, fine to medium SAND (Qop) 132.8
Light reddish brown, Silty, fine to medium SAND (Qop) 130.5
TABLE 8-11
Optimum Moisture
Content(% dry wt.)
8.1
9.0
SUMMARY OF LABORATORY DIRECT SHEAR TEST RESULTS
ASTM D 3080
Dry Density Moisture Content(%) Peak l Ultimate1]
Peak [Ultimate1 I
Angle of Shear (pct) Initial Final Cohesion (psf) Resistance (degrees)
121.8 6.6 I 3.4 500 [400] 27 [26]
118.6 8.7 13.7 700 [550] 27 [24]
1 Ultimate at end oftest at 0.2-inch deflection.
2 Remolded to a dry density of about 90 percent of the laboratory maximum dry density.
Sample
No.
T3-l
T4-I
T7-l
TABLE B-111
SUMMARY OF LABORATORY EXPANSION INDEX TEST RESULTS
ASTM D 4829
Moisture Content(%) Dry Density Expansion 2016 CBC
Expansion
Before Test After Test (pct) lndex Classification
11.5 23.4 103.8 35 Expansive
8.7 17.2 115.6 18 Non-Expansive
7.8 14.1 117.2 0 Non-Expansive
Project No. 02192-52-0 I -B-1 -
ASTM Soil
Expansion
Classification
Low
Very Low
Very Low
January 17, 2018
TABLE B-IV
SUMMARY OF LABORATORY WATER-SOLUBLE SULFATE TEST RESULTS
CALIFORNIA TEST NO. 417
Sa mple No. Water Soluble Sulfate(%) ACI 318-14 Sulfate Class
Tl-1 0.032 so
T7-1 0.009 so
TABLE B-V
SUMMARY OF LABORATORY RESISTANCE VALUE (R-VALUE) TEST RESULTS
ASTM D 2844
Sample No. Depth (feet) Description (Geologic Unit) R-Value
T7-l 2-3 Light reddish brown, Si lty, fi ne to medium SAND (Qop) 44
Project No. G2 l 92-52-0 I -B-2 -January 17, 2018
PROJECT NO. 82192-52-01
GRAVEL SAND
COARSE I FINE COARSE MEDIUM FINE SILT OR CLAY
U.S. STANDARD SIEVE SIZE
3" 1-1 /2" 3/4" 3/8" 4 f10 116 30 50 20 40 60 1Q0 21 0
100 I I I I
I I ~ I
90 II I I
I I \ I
I I ~ I
80 I I I
I I ~~ I
I I I
I I I t-70 I \ (9 I I I
w I I ~ I s 60 I I I
>-I I ' I
Cl) I I I
CI'. I I I w 50 I I
'
I z
u:::: I I I
t-I I I z 40 I", ... w I I u "1 ... CI'. I I I "'::::: w 30 II II II ~
Q_ I I I l~ I I I .... N~ I I I ~
20 ....... r---II II II r--, r-----; D I I I --~-I I I
10 I' I I I
I I I
0 II II II
10 1 0.1 0 .01 0.001
GRAIN SIZE IN MILLIMETERS
ASTM D422
SAMPLE DEPTH (ft) CLASSIFICATION NATWC LL PL Pl
• T1-1 2.0 SC -Clayey SAND
Ill T1-2 6.0 SM -Silty SAND
•
GRADATION CURVE
1534 MAGNOLIA AVENUE
CARLSBAD, CALIFORNIA
G2192-52-01.GPJ Figure B-1
GEOCON
APPENDIX
APPENDIX C
STORM WATER MANAGEMENT INVESTIGATION
FOR
1534 MAGNOLIA AVENUE
CARLSBAD, CALIFORNIA
PROJECT NO. G2192-52-01
APPENDIX C
STORM WATER MANAGEMENT INVESTIGATION
We understand storm water management devices will be used in accordance with the BMP Design
Manual currently used by the City of Carl sbad. 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 C-1 presents the
descriptions of the hydro logic soil groups. If a soil is assigned to a dual hydro logic group (AID, BID,
or CID), the first letter is for drained areas and the second is for undrained areas. In addition, the
USDA website also provides an estimated saturated hydraulic conductivity for the existing soil.
TABLE C-1
HYDROLOGIC SOIL GROUP DEFINITIONS
Soil Group Soil Group Definition
Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist
A mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a
high rate of water transmission.
Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of
B moderately deep or deep, moderately well drained or well drained soils that have moderately
fine texture to moderately coarse texture. These soils have a moderate rate of water
transmission.
Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a
C 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 property is underlain by natural materials consisting of undocumented fill and Old Paralic
Deposits and should be classified as Soil Group D. Table C-11 presents the information from the
-C-1 -
USDA website for the subject property. The Hydrologic Soil Group Map, provided at the end of this
appendix, presents output from the USDA website showing the limits of the soil units.
TABLE C-11
USDA WEB SOIL SURVEY -HYDROLOGIC SOIL GROUP
Approximate ksAT of
Map Unit Hydro logic Most Limiting Map Unit Name Symbol Percentage Soil Group Layer of Property (inches/hour)
Chesterton-Urban Land Complex, CgC 83 D 0.00 -0.06 2 to 9 percent slopes
Marina Loamy Coarse Sand, MIC 17 B 0.57 -1.42 2 to 9 percent slopes
In-Situ Testing
The infiltration rate, percolation rates and saturated hydraulic conductivity are different and have
different meanings. Percolation rates tend to overestimate infiltration rates and saturated hydraulic
conductivities by a factor of 10 or more. Table C-III describes the differences in the definitions.
TABLE C-111
SOIL PERMEABILITY DEFINITIONS
Term Definition
The observation of the flow of water through a material into the ground
Infiltration Rate downward into a given soil structure under long term conditions. This is
a function of layering of soil, density, pore space, discontinuities and
initial moisture content.
The observation of the flow of water through a material into the ground
Percolation Rate downward and laterally into a given soil structure under long term
conditions. This is a function of layering of soil, density, pore space,
discontinuities and initial moisture content.
The volume of water that will move in a porous medium under a
Saturated Hydraulic hydraulic gradient through a unit area. This is a function of density,
Conductivity (ksAT, Permeability) structure, stratification, fines content and discontinuities. It is also a
function of the properties of the liquid as well as of the porous medium.
The degree of soil compaction or in-situ density has a significant impact on soil permeability and
infiltration. Based on our experience and other studies we performed, an increase in compaction
results in a decrease in soil permeability.
We performed 2 percolation tests within Trenches T-2 and T-3 at the locations shown on the attached
Geologic Map, Figure 2. The results of the tests provide parameters regarding the percolation rate and
-C-2 -
the saturated hydraulic conductivity/infiltration characteristics of on-site soil and geologic units.
Table C-IV presents the results of the estimated fie ld saturated hydraulic conductivity and estimated
infi ltration rates obtained from the percolation tests. The calculation sheets are attached herein. We
used a factor of safety applied to the test results on the worksheet values. The designer of storm water
devices should apply an appropriate factor of safety. Soil infiltration rates from in-situ tests can vary
significantly from one location to another due to the heterogeneous characteristics inherent to most
soil. Based on a discussion in the County of Riverside Design Handbook for Low Impact
Development Best Management Practices, the infiltration rate should be considered equal to the
saturated hydraulic conductivity rate.
TABLE C-IV
FIELD PERMEAMETER INFILTRATION TEST RESULTS
Test Depth Geo logic Percolation Field -Saturated C.4-1 Worksheet
Test Location Rate Infiltration Rate, Infiltration Rate', (feet) Unit (minutes/inch) ksat (inch/hour) ksat (inch/hour)
P-1 (T-2) 6 Qop 187.5 0.07 0.04
P-2 (T-3) 6 Qop 106.0 0.32 0.16
Average: 146.8 0.20 0.10
1 Using a factor of safety of 2.
Infiltration categories include full infiltration, partial infiltration and no infiltration. Table C-V
presents the commonly accepted definitions of the potential infiltration categories based on the
infiltration rates.
Infiltration Category
Full Infiltration
Partial Infiltration
No Infiltration (Infeasible)
1 Using a Factor of Safety of 2.
Groundwater Elevations
TABLE C-V
INFILTRATION CATEGORIES
Field Infiltration Rate, I
(inches/hour)
I > 1.0
0.10 <1 <1.0
[<0.10
Factored Infiltration Rate1, I
(inches/hour)
I > 0.5
0.05 <I < 0.5
I < 0.05
We did not encounter groundwater or seepage during the site investigation. We expect groundwater
exists at depths greater than 50 feet below existing grades.
-C-3 -
New or Existing Utilities
Utilities will be constructed within the site boundaries. Full or partial infiltration should not be
allowed in the areas of the utilities to help prevent potential damage/distress to improvements.
Mitigation measures to prevent water from infiltrating the utilities consist of setbacks, installing
cutoff walls around the utilities and instal ling subdrains and/or installing liners. The horizontal and
vertical setbacks for infiltration devices should be a minimum of 10 feet and a 1: 1 plane of 1 foot
below the closest edge of the deepest adjacent utility, respectively.
Existing and Planned Structures
Existing residential and roadway structures exist adjacent to the site. Water should not be allowed to
infiltrate in areas where it could affect the neighboring properties and existing adjacent structures,
improvements and roadway. Mitigation for existing structures consists of not allowing water
infiltration within a lateral distance of at least 10 feet from the new or existing foundations.
Slopes Hazards
Slopes are not currently planned or exist on the property that wou ld be affected by potential infiltration
locations. Therefore, infiltration in regards to slope concerns wou ld be considered feasible.
Storm Water Evaluation Narrative
As discussed herein, the property consists of existing undocumented fill overlying Old Paralic
Deposits (Qop). Water should not be allowed to infiltrate into the undocumented or compacted fi ll
within the basins as it will all ow for lateral migration to adjacent residences. We evaluated the
infiltration rates within the Old Paralic Deposits within the proposed basin areas to help evaluate if
infiltration is feasible.
We performed the infiltration tests at location where the basins would be practical based on the
topography of the property and discussions with the Client. We performed the percolation tests at the
lower elevations of the property and adjacent to the existing storm drain system. Our in-place
infi ltration tests indicate an average of 0.10 inches/hour (including a factor of safety of 2); therefore,
the site is considered feasible for partial infiltration.
We do not expect geologic hazards to exist on the property. Therefore, partial infiltration may be
considered feasible within the Old Paralic Deposits.
Storm Water Management Devices
Liners and subdrains should be incorporated into the design and construction of the planned storm
water devices. The liners should be impermeable (e .g. High-density polyethylene, HDPE, with a
-C-4 -
thickness of about 30 mil or equivalent Polyvinyl Chloride, PVC) to prevent water migration. The
subdrains should be perforated within the liner area, installed at the base and above the liner, be at
least 3 inches in diameter and consist of Schedu le 40 PVC pipe. The subdrains outside of the liner
should consist of solid pipe. The penetration of the liners at the subdrains shou ld be properly
waterproofed. The subdrains shou ld be connected to a proper outlet. The devices should also be
installed in accordance with the manufacturer's recommendations. Liners should be installed on the
side walls of the proposed basins in accordance with a partial infi ltration design.
Storm Water Standard Worksheets
The BMP Design Manual requests the geotechnical engineer complete the Categorization of
Infiltration Feasibility Condition (Worksheet C.4-1 or I-8) worksheet information to help evaluate the
potential for infiltration on the property. The attached Worksheet C.4-1 presents the completed
information for the submittal process.
The regional storm water standards also have a worksheet (Worksheet D.5-1 or Form I-9) that helps
the project civil engineer estimate the factor of safety based on several factors. Table C-VI describes
the suitability assessment input parameters related to the geotechnical engineering aspects for the
factor of safety determination.
TABLE C-VI
SUITABILITY ASSESSMENT RELATED CONSIDERATIONS FOR INFILTRATION FACILITY
SAFETY FACTORS
Consideration High Medium Low
Concern -3 Points Concern -2 Points Concern -1 Point
Use of soil survey maps or Use of well permeameter
or borehole methods with simple texture analysis to accompanying Direct measurement with
estimate short-term localized (i .e. small-
infiltration rates. Use of continuous boring log. scale) infiltration testing Direct measurement of
Assessment Methods well permeameter or infiltration area with methods at relatively high
borehole methods without localized infiltration resolution or use of
accompanying continuous measurement methods extensive test pit
boring log. Relatively (e.g., lnfiltrometer). infiltration measurement
sparse testing with direct Moderate spatial methods.
infiltration methods resolution
Predominant Soil Si lty and clayey soi ls Loamy soils Granular to slightly
Texture with significant fines loamy soils
Highly variable soils Soil boring/test pits Soil boring/test pits indicated from site Site Soil Variability 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 faci lity bottom
-C-5 -
Based on our geotechnical investigation and the previous table, Table C-VII 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 C-VII
FACTOR OF SAFETY WORKSHEET DESIGN VALUES-PART A1
Suitability Assessment Factor Category Assigned Factor Product
Weight (w) Value (v) (p = W Xv)
Assessment Methods 0.25 2 0.50
Predominant Soil Texture 0.25 2 0.50
Site Soil Variability 0.25 2 0.50
Depth to Groundwater/ Impervious Layer 0.25 I 0.25
Suitability Assessment Safety Factor, SA = Lp 1.75
1 The project civil engineer should complete Worksheet D.5-l or Form 1-9 using the data on this table.
Additional information is required to evaluate the design factor of safety.
-C-6 -
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
Is the estimated reliable infiltration rate below proposed
facility locations greater than 0.5 inches per hour? The response
to this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.2 and Appendix
D.
Provide basis:
Yes No
X
Based on the USGS Soil Survey, the property possesses Hydrologic Soil Group D classifications. In addition, we
encountered field infiltration rates of:
T-2/P-I: 0.07 inches/hour (0.04 with a FOS of2.0)
T-3!P-2: 0.32 inches/hour (0.16 with a FOS of2.0)
This results in an average infiltration rate of0.20 inches/hour (0.10 with an FOS of2.0).
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability.
2
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) that cannot
be mitigated to an acceptable level? The response to this
Screening Question shall be based on a comprehensive evaluation of
the factors presented in Appendix C.2.
Provide basis:
X
Undocumented fill and Old Paralic Deposits underlie the property. Water that would be allowed to infiltrate could
migrate laterally outside of the property limits to the ex isting right-of-ways (located to the south and west) and
toward existing and proposed structures (located to the north and east). However, we expect the basins would be
setback a sufficient distance from the existing and proposed utilities and structures to help alleviate seepage and
underground utility concerns. Additionally, the use of vertical cutoff walls or liners, as recommended herein, would
prevent lateral migration of water. The bottom of the basins should expose Old Paralic Deposits.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability.
-C-7 -
Criteria
3
Provide basis:
Screening Question
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 factors) that cannot
be mitigated to an acceptable level? The response to this
Screening Question shall be based on a comprehensive evaluation of
the factors presented in Appendix C.3.
Yes No
X
We did not encounter groundwater during the drilling operations on the property. We anticipate that groundwater is
present at depths of greater than 50 feet. Therefore, infiltration due to groundwater elevations would be considered
feasible. Additionally, we understand that contaminated soil or groundwater has not been documented or identified
at the property. Therefore, infiltration due to groundwater concerns would be considered feasible.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability.
4
Provide basis:
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 discharge of
contaminated groundwater to surface waters? The response to
this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.3.
X
We do not expect full infiltration would cause water balance issues including change of ephemeral streams or
discharge of contaminated water to surface waters.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability.
Part 1
Result*
If all answers to rows 1 -4 are "Yes" a full infiltration design is potentially feasible.
The feasibility screening category is Full Infiltration
If any answer from row 1-4 is "No", infiltration may be possible to some extent but
would not generally be feasible or desirable to achieve a "full infiltration" design.
Proceed to Part 2
Not Full
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 the City to substantiate findings.
-C-8 -
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
5
Provide basis:
Screening Question
Do soil and geologic conditions allow for infiltration in any
appreciable rate or volume? The response to this Screening
Question shall be based on a comprehensive evaluation of the
factors presented in Appendix C.2 and Appendix D.
Yes
X
No
Based on the USGS Soil Survey, the property possesses Hydrologic Soil Group D classifications. In addition, we
encountered field infiltration rates of:
T-2/P-l: 0.07 inches/hour (0 .04 with a FOS of2.0)
T-3/P-2: 0.32 inches/hour (0.16 with a FOS of2.0)
This results in an average infiltration rate of 0.20 inches/hour (0.10 with an FOS of 2.0).
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.
6
Provide basis:
Can Infiltration in any appreciable quantity be allowed
without increasing risk of geotechnical hazards (slope
stability, groundwater mounding, utilities, or other factors)
that cannot be mitigated to an acceptable level? The response
to this Screening Question shall be based on a comprehensive
evaluation of the factors presented in Appendix C.2.
X
Undocumented fill and Old Paralic Deposits underlie the property. Water that would be allowed to infiltrate could
migrate laterally outside of the property limits to the existing right-of-ways (located to the south and west) and
toward existing and proposed structures (located to the north and east). However, we expect the basins would be
setback a sufficient distance from the existing and proposed utilities and structures to help alleviate seepage and
underground utility concerns. Additionally, the use of vertical cutoff walls or liners, as recommended herein, would
prevent lateral migration of water. The bottom of the basins should expose Old Paralic Deposits.
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.
-C-9 -
Criteria
7
Provide basis:
Screening Question
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.
Yes No
X
We did not encounter groundwater during the drilling operations on the property. We anticipate that groundwater is
present at depths of greater than 50 feet. Therefore, infiltration due to groundwater elevations would be considered
feasible. Additionally, we understand that contaminated soil or groundwater has not been documented or identified
at the property. Therefore, infiltration due to groundwater concerns would be considered feasible.
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.
8
Provide basis:
Can infiltration be allowed without violating downstream
water rights? The response to this Screening Question shall be
based on a comprehensive evaluation of the factors presented in
Appendix C.3.
X
We did not provide a study regarding water rights. However, these rights are not typical in the San Diego area.
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.
Part 2
Result*
If all answers from row 1-4 are yes then partial infiltration design is potentially feasible.
The feasibility screening category is Partial Infiltration.
If any answer from row 5-8 is no, then infiltration of any volume is considered to be
infeasible within the drainage area. The feasibility screening category is No Infiltration.
Partial
Infiltration
*To be completed using gathered site information and best professional judgment considering the definition ofMEP in the
MS4 Permit. Additional testing and/or studies may be required by the City to substantiate findings.
-C-IO -
~ GEOCON
Excavation Percolation Test
Project Name: 1534 Magnolia -----'-----Date: 9/27/2017
Project Number: G2192-52-01 By: JML ---------0 pen -Pit Location: T-2 (P-1) ---------
Test Hole Length (in.) 14.0 ----
Test Hole Width (in.) 12.0 _______ ,;.__;_ ____ or
Test Hole Dia. (in.)
Test Hole Depth (in.) 10.5 Test Hole Area, A, (in.2) 168.0 -----
L:-.t /f..D tJ,,v/1:J.t (Q/A)*60
Depth of Cumulative Wetted Change in Percolation Flow Rate, Infiltration
Time, t Reading Water, D /:;,t (min) Time,t /ill (in.) Area,A w,t Volume, Rate Q Rate, / t
(min) (in.) (min) (in.2) t:,. V (in .3) (min/in.) (in .3/min) (in./hr)
1 0.0 8.25 15.00 15.00 0.06 595.38 10.50 240.00 0.70 0.07 15.0 8.19
2 0.0 8.50 15.00 30.00 0.01 609.74 1.68 1500.00 0.11 0.01 15.0 8.49
3 0.0
15.0
8.50
8.25 15.00 45.00 0.25 603.50 42.00 60.00 2.80 0.28
4 0.0 8.50 15.00 60.00 0.01 609.74 1.68 1500.00 0.11 0.01 15.0 8.49
5 0.0 8.50 15.00 75.00 0.01 609.74 1.68 1500.00 0.11 0.01 15.0 8.49
6 0.0 8.50 15.00 90.00 0.06 608.38 10.50 240.00 0.70 0.07 15.0 8.44
7 0.0 9.00 15.00 105.00 0.01 635.74 1.68 1500.00 0.11 0.01 15.0 8.99
8 0.0 9.00 15.00 120.00 0.06 634.38 10.50 240.00 0.70 0,07 15.0 8.94
9 0.0 9.00 15.00 135.00 0.01 635.74 1.68 1500.00 0.11 O.Ql
15.0 8.99
10 0.0
15.0
9.00
8.93 15.00 150.00 0.07 634.18 11.76 214.29 0.78 0,07
11 0.0 9.00 15.00 165.00 0.08 633.92 13.44 187.50 0.90 0.08 15.0 8.92
12 0.0 9.25 15.00 180.00 0.05 647.70 8.40 300.00 0.56 0.05 15.0 9.20
13
14
2.00 Qj .... t1I 1.50 cc: -C: ...
0 .s::. 1.00 ·-........ .... t1I C: ... ·-~-0.50 ..:;:
E ..... 0.00 ----~ .... -----·-_,,,-----4 . .,_ ______ .. =--•--..... •-----4·.,_ __ _
0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00 200.00
Time (min)
Percolation Rate (Minutes/Inch) = 187.5
0.07
Soil Infiltration Rate (Inches/Hour)
~ GEOCON
Excavation Percolation Test
Project Name: __ l_S_3_4_M_a....;g;_n_o_li_a __
Project Number: G2192-52-01 ---------Open-Pit Location: T-3 (P-2) ____ ...;._-'----
Test Hole Length (in.) 14.0 ----
Test Hole Width (in.) 12.0 -------------or
Test Hole Dia. (in.)
Test Hole Depth (in.)
Depth of
Reading Time, t Water, D h.t (min) (min) (in.)
1 0.0 8.50 15.00 15.0 8.00
2 0.0 8.50 15.00 15.0 8.44
3 0.0 8.50 15.00 15.0 8.38
4 0.0 8.50 15.00 15.0 8.49
5 0.0 8.50 15.00 15.0 8.00
6 0.0 8.19 15.00 15.0 8.00
7 0.0 8.50 15.00 15.0 8.06
8 0.0 8.50 15.00 15.0 8.44
9 0.0 8.75 15.00 15.0 8.44
10 0.0 8.75 15.00 15.0 8.25
11 0.0 8.25 15.00 15.0 8.19
12
13
14
2.00 QI ... Ill 1.50 et:: -C: ...
0 .J::. 1.00 ·-....... ... . Ill C: ... ·-... -0.50 :E .E 0.00
0.00 20.00 40.00
Percolation Rate (Minutes/Inch)
Soil Infiltration Rate (Inches/Hour)
11.0
Cumulative
Time, t
(min)
15.00
30.00
45.00
60.00
75.00
90.00
105.00
120.00
135.00
150.00
165.00
60.00
/ill (in.)
0.50
0.06
0.13
0.01
0.50
0.19
0.44
0.06
0.31
0.50
0.06
80.00
Time (min)
Date: 9/27/2017
By: JML
Test Hole Area, A, (in. 2) 168.0 -----
1'.t /1'.D t:i.v/!J.t (Q/A}*60
Wetted Change in Percolation Flow Rate, Infiltration
Area,A w,, Volume, Rate Q Rate, / t
(in .2) /",. V (in.3) (min/in.) (in.3/min) (in./hr)
597.00 84.00 30.00 5.60 0.56
608.38 10.50 240.00 0.70 0.07
606.75 21.00 120.00 1.40 0.14
609.74 1.68 1500.00 0.11 0.Dl
597.00 84.00 30.00 5.60 0.56
588.88 31.50 80.00 2.10 0.21
598.63 73.50 34.29 4.90 0.49
608.38 10.50 240.00 0.70 0.07
614.88 52.50 48.00 3.50 0.34
610.00 84.00 30.00 5.60 0.55
595.38 10.50 240.00 0.70 O.D7
100.00 120.00 140.00 160.00 180.00
106.0
0.32
t
N
HYDROLOGIC SOIL SURVEY
GEOCON
INCORPORATED
GEOTECHNICAL ■ ENVIRONMENTAL ■ MATERIALS
6960 FLANDERS DRIVE -SAN DIEGO, CALIFORNIA 92121 -297 4
PHONE 858 558-6900 -FAX 858 558-6159
ML /CW I I DSK/GTYPD
1534 MAGNOLIA AVENUE
CARLSBAD, CALIFORNIA
DATE 01 -17 -2018 I PROJECT NO.G2192 -52 -01 I FIG. C-1
Plotted:01/17/2018 8:10AM I By:JONATHAN WILKINS I FIie Localion:Y:\PROJECTS\G2192-52-01 1534 Magnolia Ave\DETAILS\G2192-52-01_HydrologlcSollSurvey.dwg
APPENDIX
APPENDIX D
RECOMMENDED GRADING SPECIFICATIONS
FOR
1534 MAGNOLIA AVENUE
CARLSBAD, CALIFORNIA
PROJECT NO. G2192-52-01
RECOMMENDED GRADING SPECIFICATIONS
1. GENERAL
1.1 These Recommended Grading Specifications shal l be used in conju nction 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 Consu ltant 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 accompli sh 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 gradin g 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 fo r 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 shall be
responsible for having qualified representatives on-site to observe and test the Contractor's
work for conformance with these specifications.
2.6 Engineering Geologist shall refer to a California licensed Engineering Geologist retained
by the Owner to provide geologic observations and recommendations during the site
grading.
2.7 Geotechnical Report shall refer to a soil report (including all addenda) which may include
a geologic reconnaissance or geologic investigation that was prepared specifically for the
development of the project for which these Recommended Grading Specifications are
intended to apply.
3. MA TE RIALS
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 ¾ 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 ¾ 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 1 O; 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 m the
Geotechnical Report may be encountered by the Contractor. The Consultant shall be
notified immediately to evaluate the significance of the unanticipated condition.
4. CLEARING AND PREPARING AREAS TO BE FILLED
4.1 Areas to be excavated and filled shall be cleared and grubbed. Clearing shall consist of
complete removal above the ground surface of trees, stumps, brush, vegetation, man-made
structures, and similar debris. Grubbing shall consist of removal of stumps, roots, buried
logs and other unsuitable material and shall be performed in areas to be graded. Roots and
other projections exceeding I ½ inches in diameter shall be removed to a depth of 3 feet
below the surface of the ground. Borrow areas shall be grubbed to the extent necessary to
provide suitable fill materials.
4.2 Asphalt pavement material removed during clearing operations should be properly
disposed at an approved off-site facility or in an acceptable area of the project evaluated by
Geocon and the property owner. Concrete fragments that are free of reinforcing steel may
be placed in fills, provided they are placed in accordance with Section 6.2 or 6.3 of this
document.
GI rev. 07 /20 I 5
4.3 After clearing and grubbing of organic matter and other unsuitable material, loose or
porous soils shall be removed to the depth recommended in the Geotechnical Report. The
depth of removal and compaction should be observed and approved by a representative of
the Consultant. The exposed surface shall then be plowed or scarified to a minimum depth
of 6 inches and until the surface is free from uneven features that would tend to prevent
uniform compaction by the equipment to be used.
4.4 Where the slope ratio of the original ground is steeper than 5: I (horizontal:vertical), or
where recommended by the Consultant, the original ground should be benched in
accordance with the following illustration.
TYPICAL BENCHING DETAIL
Finish Grade Original Ground
.............. 2
',,~1
',,,,,, ;-Finish Slope Surface
,, j
Remove All
Unsuitable Material
As Recommended By
Consultant Slope To Be Such That
Sloughing Or Sliding
Does Not Occur
',,
.................... ,,
',,,',,,,
,,
.................. ,, ',,
-----
See Note 2
No Scale
DETAIL NOTES: (1) Key width "B" should be a minimum of 10 feet, or sufficiently wide to permit
complete coverage with the compaction equipment used. The base of the key should
be graded horizontal, or inclined slightly into the natural slope.
(2) The outside of the key should be below the topsoil or unsuitable surficial material
and at least 2 feet into dense formational material. Where hard rock is exposed in the
bottom of the key, the depth and configuration of the key may be modified as
approved by the Consultant.
4.5 After areas to receive fill have been cleared and scarified, the surface should be moisture
conditioned to achieve the proper moisture content, and compacted as recommended m
Section 6 of these specifications.
GI 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. 07/20 15
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 m 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 w ith 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. 1n 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 fo llowed. 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
subd rains 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
NOTES;
1-~1 DWET£R, SCHtmUlJ! llO PVC PER.FORATm PIPE FOfl FIU.8
INEXC=SS Of 100-f'EET IN OEPTH ORA.PIPE LENGTWOF LOlfGER THAN l!OO FEET.
:Z.. -~ OIAMl:TER. so-tEOlA.E 40 FVC PERFOAATED PIPE FOR RU.S
LESS niMI 00-FEFr IN DEPTH OR A P<:PE LENGTH 5tlOATER ™AH 600 FEET.
BEDROCK
NO~ f1'IAI. Z0' o,· AT 0111'\J!T
&W,I..Ltl[~T[!)
9 CU81C FffT I FQO't OF 0P9I
CIW>EO GRAY£1. ~ BY MIIW"1140NC (OR EOJNAL.Bn')
'l. MllRIC
NO SCALE
7.2 Slope drains within stability fill keyways should use 4-inch-diameter (or lager) pipes.
GI rev. 07/20 15
TYPICAL STABILITY FILL DETAIL
1-ElCCAYATE IACKCUT AT i 1 NCI.JM,t,llO'i (UNLE&S OT)-~ N0TED~
7.. !IEOFIITMII nYF1ll. TOOO lA:£1 MO FORJ.u.llt)tW. *Tf'111Al,81 !NOA MINIMUM !1'11 INTOIIIOl"E.
3.-STABUTY Fil. TO IE OOW?OSB> Of PROPEAL Y
4 .. ...0-.NZY ~ 10 APPfiOVYl PREfAOMICATN> CIIIMHt:Y ~ PMB..S (~N G2ICDI OllloQU;Vl'IIL.Nf)
$PACED ~TE Y lll F£ET ~ to CEtltelt AHb • F&'I' W!llt. 0..0IIEA IIPt,CIMG tlAY E REOWAm ,_
fiEEf'AOI' Iii~ 0.
5,-,fU'ER MATERIAL TC • 114-M:ti, OPfM-OIW)fl> CRUSHEJ> R00( EHCI..OIEO APPROVED FI.Tl:'R FABAIC (MIIW'l ~
e ..... COUt:CIOR l'<IPC TO 4-INCI~ MINl,ll.llol I.IW,t[l 4, PCRn>RAr • Tl<ICK,WAI.Ul) PVC SCltOlU..C.., OR
l!OUIVAl.1!1,T, AVD 111.0!'!n TO MAI< AT Pl!Aa!NT ~ TO N'f"Flf:1V!!:: ounn.
NO SCALE
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 VlEW
rt,111t
SIDE VIEW
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
SIDE VIEW
rORr --
ro,,r -
NO'r1;. H!!AIMN..L 5HOUU)OIJTUT A.T tOf! 0, fill !11.0PE
OR IN'TO CONmOUfll SURl'i,()( CRAll'Wlf
,,..
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. ln 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. I .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 I 0-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. l Upon completion of the work, Contractor shall furnish Owner a certification by the Civil
Engineer stating that the lots and/or building pads are graded to within 0.1 foot vertically of
elevations shown on the grading plan and that all tops and toes of slopes are within 0.5 foot
horizontally of the positions shown on the grading plans. After installation of a section of
subdrain, the project Civil Engineer should survey its location and prepare an as-built plan
of the subdrain location. The project Civil Engineer should verify the proper outlet for the
subdrains and the Contractor should ensure that the drain system is free of obstructions.
l 0.2 The Owner is responsible for furnishing a final as-graded so il 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
LIST OF REFERENCES
1. 2016 California Building Code, California Code of Regulations, Title 24, Part 2, based on
the 2015 International Building Code, prepared by California Building Standards
Commission, dated July 1, 2016.
2. A3 Development, Conceptual Plan, 6 Lots, 1534 Magnolia Avenue, Carlsbad, California,
dated August 16, 2017.
3. ASCE 7-10, Minimum Design Loads for Buildings and Other Structures, Second Printing,
April 6, 2011.
4. Boore, D. M., and G. M Atkinson (2008), Ground-Motion Prediction for the Average
Horizontal Component of PGA, PGV, and 5%-Damped PSA at Spectral Periods Between
0.01 and 10.0 S, Earthquake Spectra, Volume 24, Issue 1, pages 99-138, February 2008.
5. California Department of Water Resources, Water Data Library.
http://www.water.ca.gov/waterdatalibrary.
6. California Geological Survey, Seismic Shaking Hazards in California, Based on the
USGS/CGS Probabilistic Seismic Hazards Assessment (PSHA) Model, 2002 (revised April
2003). 10% probability of being exceeded in 50 years.
http://redirect.conservation.ca.gov/cgs/rghm/pshamap/pshamain.html
7. Campbell, K. W., and Y. Bozorgnia, NGA Ground Motion Model for the Geometric Mean
Horizontal Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response
Spectra for Periods Ranging from 0.01 to JO s, Preprint of version submitted for publication
in the NGA Special Volume of Earthquake Spectra, Volume 24, Issue 1, pages 139-171,
February 2008.
8. Chiou, Brian S. J., and Robert R. Youngs, A NGA Model for the Average Horizontal
Component of Peak Ground Motion and Response Spectra, preprint for article to be
published in NGA Special Edition for Earthquake Spectra, Spring 2008.
9. Civil Landworks, Magnolia-Brady Preliminary Tentative Map and Grading Plan, 1534
Magnolia Avenue, Carlsbad, California, dated January 5, 2018.
I 0. Geocon Incorporated, Phase I Environmental Site Assessment Report, I 534 Magnolia
Avenue, Carlsbad, California, dated October I 0, 2017 (Project No. G2 l 92-62-02).
11. Historical Aerial Photos. http://www.historicaerials.com
12. Kennedy, M. P., and S. S. Tan, Geologic Map of the Oceanside 30 'x60 ' Quadrangle,
California, USGS Regional Map Series Map No. 3, Scale 1: 100,000, 2002.
13. Risk Engineering, EZ-FRISK, 2016.
14. Unpublished reports and maps on file with Geocon Incorporated.
I 5. United States Geological Survey computer program, US. Seismic Design Maps,
http://earthquake.usgs.gov/designmaps/us/application.php.
Project No. 02192-52-01 January 17, 2018