HomeMy WebLinkAboutCT 2019-0002; MADISON FIVE; PRELIMINARY GEOTECHNICAL INVESTIGATION; 2018-10-10REPORT OF PRELIMINARY
GEOTECHNICAL INVESTIGATION
Proposed Lanshire Townhomes Project
Southeast Corner Madison Street and Oak Avenue
Carlsbad, California
JOB NO. 18-11968
10 October 2018
Prepared for:
Mr. Michael Kootchick
,~~-. ~,,..,., Geotechnical Exploration, Inc.
SOIL AND FOUNDATION ENGINEERING • GROUNDWATER • ENGINEERING GEOLOGY
10 October 2018
Mr. Michael Kootchick
SOS Property Management
11855 Sorrento Valley Road, Suite 523
San Diego, CA 92121
Job No. 18-11968
Subject: Report of Preliminary Geotechnical Investigation
Proposed Lanshire Townhomes Project
Southeast Corner of Madison Street and Oak Avenue
Carlsbad, California
Dear Mr. Kootchick:
In accordance with your request, and our proposal of August 3, 2018, Geotechnical
Exploration, Inc. has performed a preliminary geotechnical investigation and
infiltration testing for the subject property. The field work was performed on October
4, 2018.
In our opinion, if the conclusions and recommendations presented in this report are
implemented during site preparation and construction, the site will be suited for the
proposed townhomes project and associated improvements.
This opportunity to be of service is sincerely appreciated. Should you have any
questions concerning the following report, please do not hesitate to contact us.
Reference to our Job No. 18-11968 will expedite a response to your inquiries.
Respectfully submitted,
J · . Cerros, P.E.
R.C.E. 34422/G.E. 2007
Senior Geotechnical Engineer
Jona
P.G.
Seni
7420 TRADE STREET• SAN DIEGO, CA. 92121 • (858) 549-7222 e FAX: (858) 549-1604 e EMAIL: geotech@gei-sd.com
I. PROJECT SUMMARY
SCOPE OF WORK
SITE DESCRIPTION
FIELD INVESTIGATION
TABLE OF CONTENTS
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
XI.
XII.
LABORATORY TESTS & SOIL INFORMATION
REGIONAL GEOLOGIC DESCRIPTION
SITE-SPECIFIC SOIL & GEOLOGIC DESCRIPTION
GEOLOGIC HAZARDS
GROUNDWATER
CONCLUSIONS AND RECOMMENDATIONS
GRADING NOTES
LIMITATIONS
REFERENCES
FIGURES
I. Vicinity Map
II. Plot Plan
IIIa-e. Exploratory Excavation Logs
IV. Laboratory Test Results
APPENDICES
A. Unified Soil Classification System
B. Infiltration Test Data and Infiltration Rate Calculations
C. USDA Web Soil Survey Map
D. USGS Design Maps Summary Report
1
1
2
3
6
7
11
12
19
21
37
37
REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION
Proposed Lanshire Townhomes Project
Southeast Corner of Madison Street and Oak Avenue
Carlsbad, California
JOB NO. 18-11668
The following report presents the findings and recommendations of Geotechnical
Exploration, Inc. for the subject project.
I. PROJECT SUMMARY
It is our understanding, based on communications with you, that the site will be
developed to receive three-story residential townhome structures and associated
improvements. The prop'osed townhome structures are to be constructed of
standard-type building materials utilizing a conventional foundation system.
Preliminary construction plans were not made available for our review during the
preparation of this report, however, when final plans are completed they should be
made available for our review. Additional or modified recommendations will be
provided at that time if warranted.
II. SCOPE OF WORK
The scope of work performed for this investigation included a site reconnaissance and
subsurface exploration program, laboratory testing, geotechnical engineering
analysis of the field and laboratory data, infiltration testing, and the preparation of
this report. The data obtained and the analyses performed were for the purpose of
providing design and construction criteria for the project earthwork, building
foundations, and slab on-grade floors.
Proposed Lanshire Townhome Project
Carlsbad, California
III. SITE DESCRIPTION
Job No. 18-11968
Page 2
The property is known as Assessor's Parcel No. 204-031-01-00 and 204-031-02-00,
Lots 15 and 16, Block 47, per Recorded Map 775, in the City of Carlsbad, County of
San Diego, State of California. Refer to Figure No. I, the Vicinity Map, for the site
location.
The site, located on the southeast corner of Madison Street and Oak Avenue in the
City of Carlsbad, consists of approximately 0.18-acre. The property is bordered on
the north at approximately the same elevation by Oak Avenue; on the east and
slightly higher in elevation by an alley; on the west and slightly lower in elevation by
Madison Street; and on the south at approximately the same elevation by a single-
family residential property. In general, the lot slopes very gently to the west. For
Plot Plan, refer to Figure No. II.
The relatively undeveloped property consists of a small shed at the northwest corner,
and fencing around the perimeter. Vegetation on the site primarily consists of mature
trees and palm trees on the eastern portion of the property, and decorative shrubbery
and weeds across the property.
The building pad is relatively level at an approximate elevation of 54.5 feet above
mean sea level (MSL). Elevations across the property range from approximately 53
feet above MSL along the west property line to approximately 56 feet above MSL in
the southeastern corner of the property. Information concerning approximate
elevations across the site was obtained from a "Topographic Survey Madison Street"
map by Alta Consultants, dated August 2, 2018.
Proposed Lanshire Townhome Project
Carlsbad, California
IV. FIELD INVESTIGATION
A. Subsurface Investigation
Job No. 18-11968
Page 3
The field investigation consisted of a surface reconnaissance and a subsurface
exploration program utilizing hand tools to investigate and sample the subsurface
soils. Five exploratory excavations were advanced across the lot (HP-1 to HP-5).
Additionally, two infiltration tests were conducted utilizing our exploratory
excavations (HP-1/INF-1 and HP-2/INF-2). The exploratory excavations were
advanced to a maximum depth of 3 feet, in order to obtain representative soil
samples and to define the soil profile across the project area. The soils encountered
in the exploratory excavations were continuously logged in the field by our geologist
and described in accordance with the Unified Soil Classification System (refer to
Appendix A). The approximate locations of the exploratory excavations are shown
on the Plot Plan, Figure No. II.
Representative samples were obtained from the exploratory excavations at selected
depths appropriate to the investigation. All samples were returned to our laboratory
for evaluation and testing.
Exploratory excavation logs have been prepared on the basis of our observations and
laboratory test results. Logs of the exploratory excavations are attached as Figure
Nos. IIIa-e.
B. Infiltration Testing
We performed simple open pit falling head testing at two locations in the
northwestern and northeastern portions of the property, at a depth of 34 inches in
INF-1, and 36 inches in INF-2 per the requirements of the City of Carlsbad Storm
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 4
Water Standards, BMP Design Manual, in accordance with Appendix D. Testing at
the two locations (INF-1 and INF-2) revealed falling head rates of 34.286 and 60
minutes/inch, respectively. The simple open pit falling head test rate results for INF-
1 and INF-2 have been converted to infiltration rates using the Porchet Method, and
indicate infiltration rates of 0.944-and 0.462-inch/hour, respectively. A minimum
factor of safety of 2 must be applied to the recorded infiltration rates. With the
minimum factor of safety applied, the infiltration rates on site range from 0.472-to
0.231-inch/hour. Refer to Appendix B for infiltration test rates and infiltration rate
calculations.
Formational materials referred to as Quaternary-age Old Paralic deposits (Qop6-7)
were encountered underlying approximately 1 foot of fill soils in both exploratory
infiltration excavations. Laboratory test results at infiltration test location INF-1 and
INF-2, indicate 22% and 23% of the soils passed the #200 sieve, respectively.
Based on our review of USDA Web Soil Survey map, the site has been assigned to
hydrologic soil group (HSG) B. Refer to Appendix C for USDA Web Soil Survey Map.
As part of our geologic/geotechnical site evaluation, we considered the following
issues:
1. The locations where infiltration testing was conducted on the site are not
subject to high groundwater conditions (within 10 feet of the base of a
proposed infiltration BMP).
2. The site is not in relatively close proximity to a known contaminated soil site.
3. Portions of the site are underlain by artificial fill soils over medium dense silty
sand formational soils, but not subject to hydroconsolidation.
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 5
4. The site has infiltration rates between of 0.472-and 0.231-inch/hour with a
minimum factor of safety of 2 applied.
5. The locations where infiltration testing was conducted on the site do not have
a silt plus clay percentage of greater than 50.
6. The locations where infiltration testing was conducted on the site are not
underlain at relatively shallow depths by practically impermeable formational
soils.
7. The locations where infiltration testing was conducted on the site are not
located within 100 feet from a known drinking water well.
8. The locations where infiltration testing was conducted on the site are not
located within 100 feet from a known on-site septic system or designated
expansion area.
9. The locations where infiltration testing was conducted on the site are not
located adjacent to a slope steeper than 25 percent.
Based on the results of our simple open pit falling head testing and evaluation of the
infiltration rates, it is our professional opinion that the areas of the site where
infiltration testing was conducted has favorable soil conditions and appreciable
infiltration rates for the design of partial infiltration BMPs. However, we recommend
the side walls of the proposed basin be lined with impermeable liner and the basins
be located at least 10 feet away from any proposed structures, retaining walls and
utility trenches.
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 6
V. LABORATORY TESTS & SOIL INFORMATION
Laboratory tests were performed on the retrieved soil samples in order to evaluate
their index, strength, expansion, and compressibility properties. The test results are
presented on Figures Nos. IIIa-e and IV. The following tests were conducted on
representative soil samples:
1. Moisture Content (ASTM D2216-10)
2. Determination of Percentage of Particles Smaller than #200 Sieve
(ASTM D1140-17)
3. Laboratory Compaction Characteristics (ASTM D1557-12)
Moisture content measurements were performed to establish the in situ moisture of
samples retrieved from the exploratory excavations. Moisture content
measurements were performed by ASTM methods D2216. These moisture tests help
to establish the in situ moisture of samples retrieved from the exploratory
excavations.
The particle size smaller than a No. 200 sieve analysis (ASTM D1140) tests aid in
classifying the tested soils in accordance with the Unified Soil Classification System
and provide qualitative information related to engineering characteristics such as
expansion potential, permeability, and shear strength.
Laboratory compaction tests (ASTM D1557) establish the laboratory maximum dry
density and optimum moisture content of the tested soils and are also used to aid in
evaluating the strength characteristics of the soils.
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 7
The expansion potential of soils is determined, when necessary, utilizing the Standard
Test Method for Expansion Index of Soils (ASTM D4829). In accordance with the
same Standard (Table 5.3), potentially expansive soils are classified as follows:
EXPANSION INDEX POTENTIAL EXPANSION
0 to 20 Very low
21 to 50 Low
51 to 90 Medium
91 to 130 High
Above 130 Very high
Based on the particle size test results and our experience with the encountered soils,
it is our opinion that the on-site fill and formational soils, in general, possess a low
expansion potential.
VI. REGIONAL GEOLOGIC DESCRIPTION
San Diego County has been divided into three major geomorphic provinces: the
Coastal Plain, the Peninsular Ranges and the Salton Trough. The Coastal Plain exists
west of the Peninsular Ranges. The Salton Trough is east of the Peninsular Ranges.
These divisions are the result of the basic geologic distinctions between the areas.
Mesozoic metavolcanic, metasedimentary and plutonic rocks predominate in the
Peninsular Ranges with primarily Cenozoic sedimentary rocks to the west and east of
this central mountain range (Demere, 1997).
In the Coastal Plain region, where the subject property is located, the "basement"
consists of Mesozoic crystalline rocks. Basement rocks are also exposed as high relief
areas (e.g., Black Mountain northeast of the subject property and Cowles Mountain
near the San Carlos area of San Diego). Younger Cretaceous and Tertiary sediments
lap up against these older features. These sediments form a "layer cake" sequence
~
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 8
of marine and non-marine sedimentary rock units, with some formations up to 140
million years old. Faulting related to the La Nacion and Rose Canyon Fault zones has
broken up this sequence into a number of distinct fault blocks in the southwestern
part of the county. Northwestern portions of the county are relatively undeformed
by faulting (Demere, 1997).
The Peninsular Ranges form the granitic spine of San Diego County. These rocks are
primarily plutonic, forming at depth beneath the earth's crust 140 to 90 million years
ago as the result of the subduction of an oceanic crustal plate beneath the North
American continent. These rocks formed the much larger Southern California
batholith. Metamorphism associated with the intrusion of these great granitic masses
affected the much older sediments that existed near the surface over that period of
time. These metasedimentary rocks remain as roof pendants of marble, schist, slate,
quartzite and gneiss throughout the Peninsular Ranges. Locally, Miocene-age
volcanic rocks and flows have also accumulated within these mountains (e.g.,
Jacumba Valley). Regional tectonic forces and erosion over time have uplifted and
unroofed these granitic rocks to expose them at the surface (Demere, 1997).
The Salton Trough is the northerly extension of the Gulf of California. This zone is
undergoing active deformation related to faulting along the Elsinore and San Jacinto
Fault Zones, which are part of the major regional tectonic feature in the southwestern
portion of California, the San Andreas Fault Zone. Translational movement along
these fault zones has resulted in crustal rifting and subsidence. The Salton Trough,
also referred to as the Colorado Desert, has been filled with sediments to depth of
approximately 5 miles since the movement began in the early Miocene, 24 million
years ago. The source of these sediments has been the local mountains as well as
the ancestral and modern Colorado River (Demere, 1997).
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 9
As indicated previously, the San Diego area is part of a seismically active region of
California. It is on the eastern boundary of the Southern California Continental
Borderland, part of the Peninsular Ranges Geomorphic Province. This region is part
of a broad tectonic boundary between the North American and Pacific Plates. The
actual plate boundary is characterized by a complex system of active, major, right-
lateral strike-slip faults, trending northwest/southeast. This fault system extends
eastward to the San Andreas Fault (approximately 70 miles from San Diego) and
westward to the San Clemente Fault (approximately 50 miles off-shore from San
Diego) (Berger and Schug, 1991).
In California, major earthquakes can generally be correlated with movement on
active faults. As defined by the California Division of Mines and Geology (Hart, E.W.,
1980), an "active" fault is one that has had ground surface displacement within
Holocene time (about the last 11,000 years). Additionally, faults along which major
historical earthquakes have occurred (about the last 210 years in California) are also
considered to be active (Association of Engineering Geologist, 1973). The California
Division of Mines and Geology (now the California Geological Survey) defines a
"potentially active" fault as one that has had ground surface displacement during
Quaternary time, that is, between 11,000 and 1.6 million years (Hart, E.W., 1980).
During recent history, prior to April 2010, the San Diego County area has been
relatively quiet seismically. No fault ruptures or major earthquakes had been
experienced in historic time within the greater San Diego area. Since earthquakes
have been recorded by instruments (since the 1930s), the San Diego area has
experienced scattered seismic events with Richter magnitudes generally less than
M4.0. During June 1985, a series of small earthquakes occurred beneath San Diego
Bay, three of which were recorded at M4.0 to M4.2. In addition, the Oceanside
earthquake of July 13, 1986, located approximately 26 miles offshore of the City of
Oceanside, had a magnitude of M5.3 (Hauksson and Jones, 1988).
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 10
On June 15, 2004, a M5.3 earthquake occurred approximately 45 miles southwest of
downtown San Diego (26 miles west of Rosarito, Mexico). Although this earthquake
was widely felt, no significant damage was reported. Another widely felt earthquake
on a distant southern California fault was a M5.4 event that took place on July 29,
2008, west-southwest of the Chino Hills area of Riverside County.
Several earthquakes ranging from M5.0 to M6.0 occurred in northern Baja California,
centered in the Gulf of California on August 3, 2009. These were felt in San Diego
but no injuries or damage was reported. A M5.8 earthquake followed by a M4.9
aftershock occurred on December 30, 2009, centered about 20 miles south of the
Mexican border city of Mexicali. These were also felt in San Diego, swaying high-rise
buildings, but again no significant damage or injuries were reported.
On April 4, 2010, a large earthquake occurred in Baja California, Mexico. It was
widely felt throughout the southwest including Phoenix, Arizona and San Diego in
California. This M7.2 event, the Sierra El Mayor earthquake, occurred in northern
Baja California, approximately 40 miles south of the Mexico-USA border at shallow
depth along the principal plate boundary between the North American and Pacific
plates. According to the U. S. Geological Survey this is an area with a high level of
historical seismicity, and it has recently also been seismically active, though this is
the largest event to strike in this area since 1892. The April 4, 2010, earthquake
appears to have been larger than the M6.9 earthquake in 1940 or any of the early
20th century events (e.g., 1915 and 1934) in this region of northern Baja California.
The event caused widespread damage to structures, closure of businesses,
government offices and schools, power outages, displacement of people from their
homes and injuries in the nearby major metropolitan areas of Mexicali in Mexico and
Calexico in Southern California.
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 11
This event's aftershock zone extends significantly to the northwest, overlapping with
the portion of the fault system that is thought to have ruptured in 1892. Some
structures in the San Diego area experienced minor damage and there were some
injuries. Ground motions for the April 4, 2010, main event, recorded at stations in
San Diego and reported by the California Strong Motion Instrumentation Program
(CSMIP), ranged up to 0.058g. Aftershocks from this event continue to the date of
this report along the trend northwest and south of the original event, including within
San Diego County, closer to the San Diego metropolitan area. There have been
hundreds of these earthquakes including events up to MS. 7.
On July 7, 2010, a MS.4 earthquake occurred in Southern California at 4:53 pm
(Pacific Time) about 30 miles south of Palm Springs, 25 miles southwest of Indio, and
13 miles north-northwest of Borrego Springs. The earthquake occurred near the
Coyote Creek segment of the San Jacinto Fault. The earthquake exhibited right
lateral slip to the northwest, consistent with the direction of movement on the San
Jacinto Fault. The earthquake was felt throughout Southern California, with strong
shaking near the epicenter. It was followed by more than 60 aftershocks of Ml.3
and greater during the first hour. Seismologists expect continued aftershock activity.
In the last 50 years, there have been four other earthquakes in the magnitude MS.0
range within 20 kilometers of the Coyote Creek segment: MS.8 in 1968, MS.3 on
2/25/1980, MS.0 on 10/31/2001, and MS.2 on 6/12/2005. The biggest earthquake
near this location was the M6.0 Buck Ridge earthquake on 3/25/1937.
VII. SITE-SPECIFIC SOIL & GEOLOGIC DESCRIPTION
Our field work, reconnaissance and review of the geologic map by Kennedy and Tan,
2007, "Geologic Map of Oceanside, 30'x60' Quadrangle, CA," indicate that the site is
underlain by Quaternary-age Old Paralic deposits Units 6-7 (Qop6-7) formational
:,
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 12
materials. The formational soils are overlain by approximately 1 foot of fill soils
across the lot (refer to the Excavation Logs, Figure Nos. Illa-e).
Fill Soils (Oaf): The lot is overlain by approximately 1 foot of fill soils as encountered
in all of the exploratory excavations. The encountered fill soils generally consist of
loose to medium dense, dry, gray-brown silty sand with some gravel and are
considered to have a low expansion potential.
Old Paralic Deposits (Oop6-7): The encountered formational materials generally
consist of poorly to moderately cemented, medium dense to dense, dry to damp, red-
brown, silty sand. The formational soils were encountered at a depth of
approximately 1 foot in all of the exploratory excavations. The formational soils are
considered to have a low expansion potential.
VIII. GEOLOGIC HAZARDS
The following is a discussion of the geologic conditions and hazards common to this
area of the City of Carlsbad, as well as project-specific geologic information relating
to development of the subject property.
A. Local and Regional Faults
Reference to the geologic map of the area (Kennedy and Tan, 2007), indicates that
no faults are shown to cross the site. In our explicit professional opinion, neither an
active fault nor a potentially active fault underlies the site.
Rose Canyon Fault: The Rose Canyon Fault Zone (Mount Soledad and Rose Canyon
Faults) is located approximately 5 miles southwest of the subject site. The Rose
Canyon Fault is mapped trending north-south from Oceanside to downtown San
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 13
Diego, from where it appears to head southward into San Diego Bay, through
Coronado and offshore. The Rose Canyon Fault Zone is considered to be a complex
zone of onshore and offshore, en echelon strike slip, oblique reverse, and oblique
normal faults. The Rose Canyon Fault is considered to be capable of generating an
M7.2 earthquake and is considered microseismically active, although no significant
recent earthquakes are known to have occurred on the fault.
Investigative work on faults that are part of the Rose Canyon Fault Zone at the Police
Administration and Technical Center in downtown San Diego, at the SDG&E facility in
Rose Canyon, and within San Diego Bay and elsewhere within downtown San Diego,
has encountered offsets in Holocene (geologically recent) sediments. These findings
confirm Holocene displacement on the Rose Canyon Fault, which was designated an
"active" fault in November 1991 (Hart E.W. and W. A. Bryant, 2007, Fault-Rupture
Hazard Zones in California, California Geological Survey Special Publication 42).
Coronado Bank Fault: The Coronado Bank Fault is located approximately 21 miles
southwest of the site. Evidence for this fault is based upon geophysical data (acoustic
profiles) and the general alignment of epicenters of recorded seismic activity (Greene,
1979). The Oceanside earthquake of MS.3 recorded July 13, 1986, is known to have
been centered on the fault or within the Coronado Bank Fault Zone. Although this
fault is considered active, due to the seismicity within the fault zone, it is significantly
less active seismically than the Elsinore Fault (Hileman, 1973). It is postulated that
the Coronado Bank Fault is capable of generating a M7 .6 earthquake and is of great
interest due to its close proximity to the greater San Diego metropolitan area.
Newport-Inglewood Fault: The Newport-Inglewood Fault Zone is located
approximately 5 miles northwest of the site. A significant earthquake (M6.4)
occurred along this fault on March 10, 1933. Since then no additional significant
events have occurred. The fault is believed to have a slip rate of approximately 0.6
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 14
mm/year with an unknown recurrence interval. This fault is believed capable of
producing an earthquake of M6.0 to M7.4 (SCEC, 2004).
Elsinore Fault: The Elsinore Fault is located approximately 24 miles northeast of the
site. The fault extends approximately 200 kilometers (125 miles) from the Mexican
border to the northern end of the Santa Ana Mountains. The Elsinore Fault zone is a
1-to 4-mile-wide, northwest-southeast-trending zone of discontinuous and en
echelon faults extending through portions of Orange, Riverside, San Diego, and
Imperial Counties. Individual faults within the Elsinore Fault Zone range from less
than 1 mile to 16 miles in length. The trend, length and geomorphic expression of
the Elsinore Fault Zone identify it as being a part of the highly active San Andreas
Fault system.
Like the other faults in the San Andreas system, the Elsinore Fault is a transverse
fault showing predominantly right-lateral movement. According to Hart, et al.
(1979), this movement averages less than 1 centimeter per year. Along most of its
length, the Elsinore Fault Zone is marked by a bold topographic expression consisting
of linearly aligned ridges, swales and hallows. Faulted Holocene alluvial deposits
(believed to be less than 11,000 years old) found along several segments of the fault
zone suggest that at least part of the zone is currently active.
Although the Elsinore Fault Zone belongs to the San Andreas set of active, northwest-
trending, right-slip faults in the southern California area (Crowell, 1962), it has not
been the site of a major earthquake in historic time, other than a M6.0 earthquake
near the town of Elsinore in 1910 (Richter, 1958; Toppozada and Parke, 1982).
However, based on length and evidence of late-Pleistocene or Holocene displacement,
Greensfelder (1974) has estimated that the Elsinore Fault Zone is reasonably capable
of generating an earthquake ranging from M6.8 to M7 .1. Faulting evidence exposed
in trenches placed in Glen Ivy Marsh across the Glen Ivy North Fault (a strand of the
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 15
Elsinore Fault Zone between Corona and Lake Elsinore), suggest a maximum
earthquake recurrence interval of 300 years, and when combined with previous
estimates of the long-term horizontal slip rate of 0.8 to 7 .0 mm/year, suggest typical
earthquakes of M6.0 to M7.0 (Rockwell, 1985).
San Jacinto Fault: The San Jacinto Fault is located 47 miles to the northeast of the
site. The San Jacinto Fault Zone consists of a series of closely spaced faults, including
the Coyote Creek Fault, that form the western margin of the San Jacinto Mountains.
The fault zone extends from its junction with the San Andreas Fault in San
Bernardino, southeasterly toward the Brawley area, where it continues south of the
international border as the Imperial Transform Fault (Earth Consultants International
[ECI] 2009).
The San Jacinto Fault zone has a high level of historical seismic activity, with at least
10 damaging earthquakes (M6.0 to M7 .0) having occurred on this fault zone between
1890 and 1986. Earthquakes on the San Jacinto Fault in 1899 and 1918 caused
fatalities in the Riverside County area. Offset across this fault is predominantly right-
lateral, similar to the San Andreas Fault, although some investigators have suggested
that dip-slip motion contributes up to 10% of the net slip (ECI, 2009).
The segments of the San Jacinto Fault that are of most concern to major metropolitan
areas are the San Bernardino, San Jacinto Valley and Anza segments. Fault slip rates
on the various segments of the San Jacinto are less well constrained than for the San
Andreas Fault, but the available data suggest slip rates of 12 ±6 mm/yr for the
northern segments of the fault, and slip rates of 4 ±2 mm/yr for the southern
segments. For large ground-rupturing earthquakes on the San Jacinto fault, various
investigators have suggested a recurrence interval of 150 to 300 years. The Working
Group on California Earthquake Probabilities (WGCEP, 2008) has estimated that there
is a 31 percent probability that an earthquake of M6. 7 or greater will occur within 30
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 16
years on this fault. Maximum credible earthquakes of M6.7, M6.9, and M7.2 are
expected on the San Bernardino, San Jacinto Valley and Anza segments, respectively,
capable of generating peak horizontal ground accelerations of 0.48g to 0.53g in the
County of Riverside, (ECI, 2009). A MS.4 earthquake occurred on the San Jacinto
Fault on July 7, 2010.
The United States Geological Survey has issued the following statements with respect
to the recent seismic activity on southern California faults:
The San Jacinto fault, along with the Elsinore, San Andreas, and other
faults, is part of the plate boundary that accommodates about 2
inches/year of motion as the Pacific plate moves northwest relative to
the North American plate. The largest recent earthquake on the San
Jacinto fault, near this location, the M6.5 1968 Borrego Mountain
earthquake April 8, 1968, occurred about 25 miles southeast of the July
7, 2010, M5.4 earthquake.
This MS.4 earthquake follows the 4th of April 2010, Easter Sunday, M7.2
earthquake, located about 125 miles to the south, well south of the US
Mexico international border. A M4.9 earthquake occurred in the same
area on June 12th at 8:08 pm (Pacific Time). Thus, this section of the
San Jacinto fault remains active.
Seismologists are watching two major earthquake faults in southern
California. The San Jacinto fault, the most active earthquake fault in
southern California, extends for more than 100 miles from the
international border into San Bernardino and Riverside, a major
metropolitan area often called the Inland Empire. The Elsinore fault is
more than 110 miles long, and extends into the Orange County and Los
Angeles area as the Whittier fault. The Elsinore fault is capable of a
major earthquake that would significantly affect the large metropolitan
areas of southern California. The Elsinore fault has not hosted a major
earthquake in more than 100 years. The occurrence of these
earthquakes along the San Jacinto fault and continued aftershocks
demonstrates that the earthquake activity in the region remains at an
elevated level. The San Jacinto fault is known as the most active
earthquake fault in southern California. Caltech and USGS seismologist
continue to monitor the ongoing earthquake activity using the
:;&
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 17
Caltech/USGS Southern California Seismic Network and a GPS network
of more than 100 stations.
B. Other Geologic Hazards
Ground Rupture: Ground rupture is characterized by bedrock slippage along an
established fault and may result in displacement of the ground surface. For ground
rupture to occur along a fault, an earthquake usually exceeds MS.0. If a MS.0
earthquake was to take place on a local fault, an estimated surface-rupture length 1
mile long could be expected (Greensfelder, 1974). Our investigation indicates that
the subject site is not directly on a known active fault trace and, therefore, the risk
of ground rupture is remote.
Liquefaction: The liquefaction of saturated sands during earthquakes can be a major
cause of damage to buildings. Liquefaction is the process by which soils are
transformed into a viscous fluid that will flow as a liquid when unconfined. It occurs
primarily in loose, saturated sands and silts when they are sufficiently shaken by an
earthquake. On this site, the risk of liquefaction of foundation materials due to
seismic shaking is considered to be low due to the medium dense to dense nature of
the natural-ground material and the lack of a shallow static groundwater surface
under the site. In our opinion, the site does not have a potential for soil strength
loss to occur due to a seismic event.
Tsunami: A tsunami is a series of long waves generated in the ocean by a sudden
displacement of a large volume of water. Underwater earthquakes, landslides,
volcanic eruptions, meteoric impacts, or onshore slope failures can cause this
displacement. Tsunami waves can travel at speeds averaging 450 to 600 miles per
hour. As a tsunami nears the coastline, its speed diminishes, its wave length
decreases, and its height increases greatly. After a major earthquake or other near-
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 18
shore tsunami-inducing activity occurs, a tsunami could reach the shore within a few
minutes. One coastal community may experience no damaging waves while another
may experience very destructive waves. Some low-lying areas could experience
severe inland inundation of water and deposition of debris.
Wave heights and run-up elevations from tsunami along the San Diego Coast have
historically fallen within the normal range of the tides (Joy 1968). The largest
tsunami effect recorded in San Diego since 1950 was May 22, 1960, which had a
maximum wave height of 2.1 feet (NOAA, 1993). In this event, 80 meters of dock
were destroyed and a barge sunk in Quivera Basin. Other tsunamis felt in San Diego
County occurred on November 5, 1952, with a wave height of 2.3 feet caused by an
earthquake in Kamchatka; March 9, 1957, with a wave height of 1.5 feet; May 22,
1960, at 2.1 feet; March 27, 1964, with a wave height of 3.7 feet and September 29,
2009, with a wave height of 0.5 feet. It should be noted that damage does not
necessarily occur in direct relationship to wave height, illustrated by the fact that the
damage caused by the 2.1-foot wave height in 1960 was worse than damage caused
by several other tsunamis with higher wave heights.
Historical wave heights and run-up elevations from tsunamis that have impacted the
San Diego Coast have historically fallen within the normal range of the tides (Joy,
1968). The risk of a tsunami affecting the site is considered moderate as the site is
situated at an elevation of approximately 53 feet above mean sea level and
approximately 500 feet to an exposed beach. In addition, the site is not mapped
within a possible inundation zone on the California Geological Survey's 2009
"Tsunami Inundation Map for Emergency Planning, Oceanside Quadrangle, San Diego
County."
Geologic Hazards Summarv: It is our opinion, based upon a review of the available
maps, our research and our site investigation, that the site is underlain at shallow
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 19
depth by relatively stable formational materials and is suited for the proposed
townhome project and associated improvements provided the recommendations
herein are implemented.
No significant geologic hazards are known to exist on the site that would prevent the
proposed construction. Ground shaking from earthquakes on active southern
California faults and active faults in northwestern Mexico is the greatest geologic
hazard at the property.
In our explicit professional opinion, no "active" or "potentially active" faults underlie
the project site.
IX. GROUNDWATER
No groundwater was encountered during the course of our field investigation and we
do not anticipate significant groundwater problems to develop in the future, if the
property is developed as proposed and proper drainage is implemented and
maintained. The true groundwater surface is assumed to be more than 50 feet below
the existing and planned building pads. Based on exploratory drilling throughout San
Diego County, we would expect minor seeps between the ground surface and true
water table due to transient "perching" of vadose water on exceptionally dense, low
permeability beds within the formational materials.
It should be kept in mind that any required construction operations will change
surface drainage patterns and/or reduce permeabilities due to the densification of
compacted soils. Such changes of surface and subsurface hydrologic conditions, plus
irrigation of landscaping or significant increases in rainfall, may result in the
appearance of surface or near-surface water at locations where none existed
previously. The damage from such water is expected to be localized and cosmetic in
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 20
nature, if good positive drainage is implemented, as recommended in this report,
during and at the completion of construction.
On properties such as the subject site where dense, low permeability soils exist at
shallow depths, even normal landscape irrigation practices on the property or
neighboring properties, or periods of extended rainfall, can result in shallow
"perched" water conditions. The perching (shallow depth) accumulation of water on
a low permeability surface can result in areas of persistent wetting and drowning of
lawns, plants and trees. Resolution of such conditions, should they occur, may
require site-specific design and construction of subdrain and shallow "wick" drain
dewatering systems.
Subsurface drainage with a properly designed and constructed subdrain system will
be required along with continuous back drainage behind any proposed lower-level
basement walls, property line retaining walls, or any perimeter stem walls for raised-
wood floors where the outside grades are higher than the crawl space grades.
Furthermore, crawl spaces, if used, should be provided with the proper cross-
ventilation to help reduce the potential for moisture-related problems. Additional
recommendations may be required at the time of construction.
It must be understood that unless discovered during site exploration or encountered
during site construction operations, it is extremely difficult to predict if or where
perched or true groundwater conditions may appear in the future. When site fill or
formational soils are fine-grained and of low permeability, water problems may not
become apparent for extended periods of time.
Water conditions, where suspected or encountered during construction, should be
evaluated and remedied by the project civil and geotechnical consultants. The project
developer and property owner, however, must realize that post-construction
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 21
appearances of groundwater may have to be dealt with on a site-specific basis.
Proper functional surface drainage should be implemented and maintained at the
property.
X. CONCLUSIONS AND RECOMMENDATIONS
The following conclusions and recommendations are based upon the practical field
investigation conducted by our firm, and resulting laboratory tests, in conjunction
with our knowledge and experience with similar soils in the Carlsbad area. The
opinions, conclusions, and recommendations presented in this report are contingent
upon Geotechnical Exploration, Inc. being retained to review the final plans and
specifications as they are developed and to observe the site earthwork and
installation of foundations. Accordingly, we recommend that the following paragraph
be included on the grading and foundation plans for the project.
If the geotechnical consultant of record is changed for the project, the
work shall be stopped until the replacement has agreed in writing to
accept the responsibility within their area of technical competence for
approval upon completion of the work. It shall be the responsibility of
the permittee to notify the City Engineer in writing of such change prior
to the recommencement of grading and/or foundation installation work.
A. Seismic Design Criteria
1. Seismic Design Criteria: Site-specific seismic design criteria for the proposed
residence are presented in the following table in accordance with Section 1613
of the 2016 CBC, which incorporates by reference ASCE 7-10 for seismic
design. We have determined the mapped spectral acceleration values for the
site, based on a latitude of 33.1597 degrees and longitude of -117.3454
degrees, utilizing a tool provided by the USGS, which provides a solution for
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 22
ASCE 7-10 (Section 1613 of the 2016 CBC) utilizing digitized files for the
Spectral Acceleration maps. Based on our experience with similar soil
conditions, we have assigned a Site Soil Classification of D. Refer to the "USGS
Design Maps Summary Report" presented as Appendix D.
TABLE I
Mapped Spectral Acceleration Values and Design Parameters
Fa Fv Sms
1.150 1.040 1.559 1.196
B. Preparation of Soils for Site Development
2. Clearing and Stripping: The existing vegetation on the lot should be removed
prior to the preparation of the building pad and areas to receive associated
improvements. This includes any roots from existing trees and shrubbery if
encountered. Holes resulting from the removal of root systems or other buried
obstructions that extend below the planned grades should be cleared and
backfilled with properly compacted fill.
3. Building Pad Surface and Subgrade Preparation: After the building pad has
been cleared, stripped, and the required excavations made to remove the
existing loose or disturbed surface fill, at least the upper 2 feet of pad existing
soils should be removed and recompacted. The bottom of the excavation
should be extended to expose medium dense to dense formational soils. The
bottom of the excavation should be scarified to a depth of 6 inches, moisture
conditioned, and compacted to the requirements for structural fill.
4. Material for Fill: Existing on-site soils with an organic content of less than 3
percent by volume are, in general, suitable for use as fill. Imported fill
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 23
5.
6.
material, where required, should have a low-expansion potential (Expansion
Index of 50 or less per ASTM 04829-11). In addition, both imported and
existing on-site materials for use as fill should not contain rocks or lumps more
than 6 inches in greatest dimension if the fill soils are compacted with heavy
compaction equipment (or 3 inches in greatest dimension if compacted with
lightweight equipment). All materials for use as fill should be approved by our
representative prior to importing to the site.
Expansive Soil Conditions: We do not anticipate that expansive soils will be
encountered during grading. Should such on-site soils be used as fill, they
should be moisture conditioned to at least 5 percent above optimum moisture
content, compacted to 88 to 92 percent. Soils of medium or greater expansion
potential should not be used as retaining wall backfill soils. If basement slabs
were to be built and placed directly on medium expansive formational
materials, the moisture content of the soil should be verified to be at least 3
percent above optimum, or scarification and moisture conditioning will be
required.
Fill Compaction: All structural fill should be compacted to a minimum degree
of compaction of 90 percent based upon ASTM 01557-12. Fill material should
be spread and compacted in uniform horizontal lifts not exceeding 8 inches in
uncompacted thickness. Before compaction begins, the fill should be brought
to a water content that will permit proper compaction by either: (1) aerating
and drying the fill if it is too wet, or (2) moistening the fill with water if it is too
dry. Each lift should be thoroughly mixed before compaction to ensure a
uniform distribution of moisture. For low expansive soils, the moisture content
should be within 2 percent of optimum. We do not anticipate that medium to
highly expansive soils will be encountered on the site. However, if they are
encountered, the moisture content should be at least 5 percent over optimum.
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 24
Once placed, soil moisture content of the fill soils should be maintained by
sprinkling daily. Medium to highly expansive soils should be compacted to
between 88 and 92 percent of Maximum Dry Density.
The areal extent required to remove the surficial soils should be confirmed by
our representatives during the excavation work based on their examination of
the soils being exposed. The lateral extent of the excavation and recompaction
should be at least 5 feet beyond the edge of the perimeter ground level
foundations of the new residential additions and any areas to receive exterior
improvements where feasible.
If heavy compaction equipment is utilized, oversize material more than 6
inches in diameter should be removed from the fill. If lightweight compaction
equipment is used, oversize material more than 3 inches in diameter should
be removed.
Any rigid improvements founded on the existing surface soils can be expected
to undergo movement and possible damage. Geotechnical Exploration,
Inc. takes no responsibility for the performance of any improvements built on
loose natural soils or inadequately compacted fills. Subgrade soils in any
exterior area receiving concrete improvements should be verified for
compaction and moisture within 48 hours prior to concrete placement.
No uncontrolled fill soils should remain after completion of the site work. In
the event that temporary ramps or pads are constructed of uncontrolled fill
soils, the loose fill soils should be removed and/or recompacted prior to
completion of the grading operation.
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 25
7.
8.
Trench and Retaining Wall Backfill: New utility trenches and retaining walls
should be backfilled with imported or on-site low-expansive compacted fill;
gravel is also a suitable backfill material but should be used only if space
constraints will not allow the use of compaction equipment. Gravel can also
be used as backfill around perforated subdrains. All backfill material should be
placed in lift thicknesses appropriate to the type of compaction equipment
utilized and compacted to a minimum degree of compaction of 90 percent by
mechanical means. In pavement areas, that portion of the trench backfill
within the pavement section should conform to the material and compaction
requirements of the adjacent pavement section. In addition, the low-
expansion potential fill layer should be maintained in utility trench backfill
within the building and adjoining exterior slab areas.
Our experience has shown that even shallow, narrow trenches (such as for
irrigation and electrical lines) that are not properly compacted can result in
problems, particularly with respect to shallow groundwater accumulation and
migration.
Temporary Slopes: We do not anticipate that significant cut slopes will be
required during grading operations. Based on our subsurface investigation
work, laboratory test results, and engineering analysis, temporary slopes if
required should be stable for a maximum slope height of up to 12 feet and
may be cut at a slope ratio of 0. 75: 1.0 in properly compacted fill soils or
formational materials. Some localized sloughing or raveling of the soils
exposed on the slopes, however, may occur.
Since the stability of temporary construction slopes will depend largely on the
contractor's activities and safety precautions (storage and equipment loadings
near the tops of cut slopes, surface drainage provisions, etc.), it should be the
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 26
C.
9.
contractor's responsibility to establish and maintain all temporary construction
slopes at a safe inclination appropriate to his methods of operation. No soil
stockpiles or surcharge may be placed within a horizontal distance of 10 feet
from the top edge of the excavation.
If these recommendations are not feasible due to space constraints, temporary
shoring may be required for safety and to protect adjacent property
improvements. Similarly, footings near temporary cuts should be underpinned
or protected with shoring.
Design Parameters for Proposed Foundations
Continuous Footings: Footings for new structures or improvements should
bear on undisturbed formational materials or properly compacted fill soils. The
footings for two-story structures should be founded at least 18 inches below
the lowest adjacent finished grade when founded into properly compacted fill
or into formational material. If new structures are up to three stories high,
the footings should be embedded at least 24 inches below lowest adjacent
grade. Footings located adjacent to utility trenches should have their bearing
surfaces situated below an imaginary 1.5: 1.0 plane projected upward from the
bottom edge of the adjacent utility trench.
10. Bearing Values: At the recommended depths, footings on native, medium
dense formational soil or properly compacted fill soil may be designed for
allowable bearing pressures of 2,500 pounds per square foot (psf) for
combined dead and live loads and increased one-third for all loads, including
wind or seismic. The footings should have a minimum width of 12 inches.
Footings deeper than the values recommended above may be increased by
800 psf for each additional foot in depth and 600 psf for each additional foot
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 27
in width with a total maximum static bearing capacity not exceeding 4,000 psf.
Bearing capacity may still be increased by one-third when considering seismic
or wind loading.
11. Footing Reinforcement: All continuous footings should contain top and bottom
reinforcement to provide structural continuity and to permit spanning of local
irregularities. We recommend that a minimum of two No. 5 top and two No.
5 bottom reinforcing bars be provided in the footings. Footings over 18" in
depth should be reinforced as specified by the structural engineer. A minimum
clearance of 3 inches should be maintained between steel reinforcement and
the bottom or sides of the footing. Isolated square footings should contain, as
a minimum, a grid of three No. 4 steel bars on 12-inch centers, both ways. In
order for us to offer an opinion as to whether the footings are founded on soils
of sufficient load bearing capacity, it is essential that our representative inspect
the footing excavations prior to the placement of reinforcing steel or concrete.
NOTE: The project Civil/Structural Engineer should review all reinforcing
schedules. The reinforcing minimums recommended herein are not to be
construed as structural designs, but merely as minimum reinforcement to
reduce the potential for cracking and separations.
12. Lateral Loads: Lateral load resistance for structure foundations may be
developed in friction between the foundation bottoms and the supporting
subgrade. An allowable friction coefficient of 0.40 is considered applicable. An
additional allowable passive resistance equal to an equivalent fluid weight of
300 pounds per cubic foot acting against the new foundations may be used in
design provided the footings are poured neat against the adjacent undisturbed
formational materials and/or properly compacted fill materials. In areas where
existing loose fill soils are present in front of existing or new foundations (a
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 28
horizontal distance equal to 3 times the depth of embedment), the allowable
passive resistance should be reduced to 150 pcf and friction coefficient to 0.35.
These lateral resistance values assume a level surface in front of the footing
for a minimum distance of three times the embedment depth of the footing,
or at least 7 feet to daylight to a slope face measured from top of the footing.
13. Settlement: Settlements under foundations with building loads that comply
with our recommendations are expected to be within tolerable limits for the
proposed additions. For footings designed in accordance with the
recommendations presented in the preceding paragraphs, we anticipate that
total settlements should not exceed 1 inch and that post-construction
differential angular rotation should be less than 1/240.
14. Retaining Walls: Retaining walls must be designed to resist lateral earth
pressures and any additional lateral pressures caused by surcharge loads on
the adjoining retained surface. We recommend that unrestrained ( cantilever)
walls with level backfill be designed for an equivalent fluid pressure of 38 pcf.
We recommend that restrained walls (i.e., basement walls or any walls with
angle points that restrain them from rotation) with level backfill be designed
for an equivalent fluid pressure of 56 pcf. Unrestrained walls with up to 2.0: 1.0
sloping backfill should be designed for an equivalent fluid pressure of 52 pcf.
Restrained walls with up to 2.0: 1.0 sloping backfill should be designed for an
equivalent fluid pressure of 76 pcf. Wherever walls will be subjected to
surcharge loads, they should also be designed for an additional uniform lateral
pressure equal to one-third the anticipated vertical surcharge pressure in the
case of unrestrained walls and an additional one-half the anticipated vertical
surcharge pressure in the case of restrained walls.
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 29
If shoring is required due to limited space constraints, the soil pressure
recommended above remain applicable. For soil lateral resistance of soldier
piles, the passive resistance values indicated in recommendation No. 12 may
be applied in the effective width equal to 2.5 the diameter of the pile times the
depth of embedment below the lowest cut surface in front of the pile.
For seismic design of unrestrained walls over 6 feet in exposed face, we
recommend that the seismic pressure increment be taken as a fluid pressure
distribution utilizing an equivalent fluid weight of 14 pcf. For restrained walls,
we recommend the seismic pressure increment be waived. A value of KH=0.16
may be used in the design of retaining walls with computer programs such as
Retain Pro.
The preceding design pressures assume that the walls are backfilled with low
expansion potential materials (Expansion Index less than 50) and that there is
sufficient drainage behind the walls to prevent the build-up of hydrostatic
pressures from surface water infiltration. We recommend, in addition to
waterproofing, that back drainage be provided by a composite drainage
material such as MiraDrain 6000/6200 or equivalent. The backdrain material
should terminate 12 inches below the finish surface where the surface is
covered by slabs or 18 inches below the finish surface in landscape areas.
Waterproofing should continue to 6 inches above top of wall. A subdrain (such
as TotalDrain or perforated pipe in an envelope of crushed rock gravel a
maximum of 1 inch in diameter and wrapped with geofabric such as Mirafi
140N), should be placed at the bottom of retaining walls.
Backfill placed behind the walls should be compacted to a minimum degree of
compaction of 90 percent using light compaction equipment. If heavy
equipment is used, the walls should be appropriately temporarily braced.
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 30
Shoring walls, if required, may be designed for the same soil pressure indicated
above. The soldier piles passive resistance may be calculated as 750 pcf times
the diameter of the pile, times the depth of embedment of the pile below the
cut surface.
D. Concrete Slab On-Grade Criteria
Slabs on-grade may only be used on new, properly compacted fill or when bearing
on medium dense natural soils.
15. Minimum Floor Slab Reinforcement: Based on our experience, we have found
that, for various reasons, floor slabs occasionally crack. Therefore, we
recommend that all slabs on-grade contain at least a minimum amount of
reinforcing steel to reduce the separation of cracks, should they occur. Slab
subgrade soil should be verified by a Geotechnical Exploration, Inc.
representative to have the proper moisture content within 48 hours prior to
placement of the vapor barrier and pouring of concrete.
New interior floor slabs should be a minimum of 4 inches actual thickness and
be reinforced with No. 3 bars on 18-inch centers, both ways, placed at
midheight in the slab. Soil moisture content should be kept above the optimum
prior to waterproofing placement under the new concrete slab.
Slab subgrade soil should be verified by a Geotechnical Exploration, Inc.
representative to have the proper moisture content within 48 hours prior to
placement of the vapor barrier and pouring of concrete.
16. Slab Moisture Emission: Although it is not the responsibility of geotechnical
engineering firms to provide moisture protection recommendations, as a
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 31
service to our clients we provide the following discussion and suggested
minimum protection criteria. Actual recommendations should be provided by
the project architect and waterproofing consultants or product manufacturer.
Soil moisture vapor can result in damage to moisture-sensitive floors, some
floor sealers, or sensitive equipment in direct contact with the floor, in addition
to mold and staining on slabs, walls and carpets. The common practice in
Southern California is to place vapor retarders made of PVC, or of polyethylene.
PVC retarders are made in thickness ranging from 10-to 60-mil. Polyethylene
retarders, called visqueen, range from 5-to 10-mil in thickness. These
products are no longer considered adequate for moisture protection and can
actually deteriorate over time.
Specialty vapor retarding and barrier products possess higher tensile strength
and are more specifically designed for and intended to retard moisture
transmission into and through concrete slabs. The use of such products is
highly recommended for reduction of floor slab moisture emission.
The following American Society for Testing and Materials (ASTM) and American
Concrete Institute (ACI) sections address the issue of moisture transmission
into and through concrete slabs: ASTM E1745-97 (2009) Standard
Specification for Plastic Water Vapor Retarders Used in Contact Concrete Slabs;
ASTM E154-88 (2005) Standard Test Methods for Water Vapor Retarders Used
in Contact with Earth; ASTM E96-95 Standard Test Methods for Water Vapor
Transmission of Materials; ASTM E1643-98 (2009) Standard Practice for
Installation of Water Vapor Retarders Used in Contact Under Concrete Slabs;
and ACI 302.2R-06 Guide for Concrete Slabs that Receive Moisture-Sensitive
Flooring Materials.
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 32
16.1 Based on the above, we recommend that the vapor barrier consist of a
minimum 15-mil extruded polyolefin plastic (no recycled content or
woven materials permitted). Permeance as tested before and after
mandatory conditioning (ASTM El 745 Section 7 .1 and subparagraphs
7 .1.1-7 .1.5) should be less than 0.01 perms (grains/square
foot/hour/per inch of Mercury) and comply with the ASTM El 745 Class
A requirements. Installation of vapor barriers should be in accordance
with ASTM E1643. The basis of design is 15-mil StegoWrap vapor
barrier placed per the manufacturer's guidelines. Reef Industries Vapor
Guard membrane has also been shown to achieve a permeance of less
than 0.01 perms. We recommend that the slab be poured directly on
the vapor barrier, which is placed directly on the prepared surface
smooth compacted subgrade soil.
16.2 Common to all acceptable products, vapor retarder/barrier joints must
be lapped and sealed with mastic or the manufacturer's recommended
tape or sealing products. In actual practice, stakes are often driven
through the retarder material, equipment is dragged or rolled across the
retarder, overlapping or jointing is not properly implemented, etc. All
these construction deficiencies reduce the retarder's effectiveness. In
no case should retarder/barrier products be punctured or gaps be
allowed to form prior to or during concrete placement.
16.3 Vapor retarders/barriers do not provide full waterproofing for structures
constructed below free water surfaces. They are intended to help reduce
or prevent vapor transmission and/or capillary migration through the
soil and through the concrete slabs. Waterproofing systems must be
designed and properly constructed if full waterproofing is desired. The
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 33
owner and project designers should be consulted to determine the
specific level of protection required.
16.4 Following placement of any concrete floor slabs, sufficient drying time
must be allowed prior to placement of floor coverings. Premature
placement of floor coverings may result in degradation of adhesive
materials and loosening of the finish floor materials.
17. Concrete Isolation Joints: We recommend the project Civil/Structural Engineer
incorporate isolation joints and sawcuts to at least one-fourth the thickness of
the slab in any floor designs. The joints and cuts, if properly placed, should
reduce the potential for and help control floor slab cracking. We recommend
that concrete shrinkage joints be spaced no farther than approximately 20 feet
apart, and also at re-entrant corners. However, due to a number of reasons
(such as base preparation, construction techniques, curing procedures, and
normal shrinkage of concrete), some cracking of slabs can be expected.
Structural slabs should not be provided with control joints.
18. Exterior Slab Reinforcement: Exterior concrete slabs should be at least 4
inches thick. As a minimum for protection of on-site improvements, we
recommend that all nonstructural concrete slabs (such as patios, sidewalks,
etc.), be founded on properly compacted and tested fill or medium dense
native formation and be underlain (if needed) by 2 inches and no more than 3
inches of clean leveling sand, with No. 3 bars at 18-inch centers, both ways,
at the center of the slab. Exterior slabs should contain adequate isolation and
control joints.
The performance of on-site improvements can be greatly affected by soil base
preparation and the quality of construction. It is therefore important that all
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 34
improvements are properly designed and constructed for the existing soil
conditions. The improvements should not be built on loose soils or fills placed
without our observation and testing. The subgrade of exterior improvements
should be verified as properly prepared within 48 hours prior to concrete
placement. A minimum thickness of 2 feet of properly recompacted soils
should underlie the exterior slabs on-grade or they should be constructed on
dense formational soils.
For exterior slabs with the minimum shrinkage reinforcement, control joints
should be placed at spaces no farther than 15 feet apart or the width of the
slab, whichever is less, and also at re-entrant corners. Control and isolation
joints in exterior slabs should be sealed with elastomeric joint sealant. The
sealant should be inspected every 6 months and be properly maintained.
E. Pavement
19. Concrete Pavement: Our preliminary recommendation is that concrete
driveway pavements, subject only to automobile and light truck traffic be 6
inches thick and be supported directly on properly prepared/compacted on-
site subgrade soils. The upper 8 inches of the subgrade below the slab should
be compacted to a minimum degree of compaction of 95 percent just prior to
paving. The concrete should conform to Section 201 of The Standard
Specifications for Public Works Construction, 2015 Edition, for Class 560-C-
3250.
20. Permeable Pavers: Permeable pavers should consist of vehicular pavers placed
on 2 inches of #8 sand, over 6 inches of No. 51 crushed rock gravel, over
properly compacted subgrade soils to at least 95 percent. Proper surface and
subsurface drainage should be provided to the pavement areas.
Proposed Lanshire Townhome Project
Carlsbad, California
F. Site Drainage Considerations
Job No. 18-11968
Page 35
21. Erosion Control: Appropriate erosion control measures should be taken at all
times during and a~er construction to prevent surface runoff waters from
entering footing excavations or ponding on finished building pad areas.
22. Surface Drainage: Adequate measures should be taken to properly finish-
grade the lot after the structures and other improvements are in place.
Drainage waters from this site and adjacent properties should be directed away
from the footings, floor slabs, and slopes, onto the natural drainage direction
for this area or into properly designed and approved drainage facilities
provided by the project civil engineer. Roof gutters and downspouts should be
installed on the residence, with the runoff directed away from the foundations
via closed drainage lines. Proper subsurface and surface drainage will help
minimize the potential for waters to seek the level of the bearing soils under
the footings and floor slabs.
Failure to observe this recommendation could result in undermining and
possible differential settlement of the structure or other improvements on the
site or cause other moisture-related problems. Currently, the CBC requires a
minimum 1-percent surface gradient for proper drainage of building pads
unless waived by the building official. Concrete pavement may have a
minimum gradient of 0.5-percent.
23. Planter Drainage: Planter areas, flower beds and planter boxes should be
sloped to drain away from the footings and floor slabs at a gradient of at least
5 percent within 5 feet from the perimeter walls. Any planter areas adjacent
to the residence or surrounded by concrete improvements should be provided
with sufficient area drains to help with rapid runoff disposal. No water should
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 36
be allowed to pond adjacent to the residence or other improvements or
anywhere on the site.
G. General Recommendations
24. Project Start Up Notification: In order to reduce work delays during site
development, this firm should be contacted 48 hours prior to any need for
observation of footing excavations or field density testing of compacted fill
soils. If possible, placement of formwork and steel reinforcement in footing
excavations should not occur prior to observing the excavations; in the event
that our observations reveal the need for deepening or re-designing foundation
structures at any locations, any formwork or steel reinforcement in the affected
footing excavation areas would have to be removed prior to correction of the
observed problem (i.e., deepening the footing excavation, recompacting soil
in the bottom of the excavation, etc.).
25. Construction Best Management Practices (BMPs): Construction BMPs must be
implemented in accordance with the requirements of the controlling
jurisdiction. Sufficient BMPs must be installed to prevent silt, mud or other
construction debris from being tracked into the adjacent street(s) or storm
water conveyance systems due to construction vehicles or any other
construction activity. The contractor is responsible for cleaning any such
debris that may be in the street at the end of each work day or after a storm
event that causes breach in the installed construction BMPs.
All stockpiles of uncompacted soil and/or building materials that are intended
to be left unprotected for a period greater than 7 days are to be provided with
erosion and sediment controls. Such soil must be protected each day when
the probability of rain is 40% or greater. A concrete washout should be
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 37
provided on all projects that propose the construction of any concrete
improvements that are to be poured in place. All erosion/sediment control
devices should be maintained in working order at all times. All slopes that are
created or disturbed by construction activity must be protected against erosion
and sediment transport at all times. The storage of all construction materials
and equipment must be protected against any potential release of pollutants
into the environment.
XI. GRADING NOTES
Geotechnical Exploration, Inc. recommends that we be retained to verify the
actual soil conditions revealed during site grading work and footing excavation to be
as anticipated in this "Report of Preliminary Geotechnica/ Investigation" for the
project. In addition, the placement and compaction of any fill or backfill soils during
site grading work must be observed and tested by the soil engineer.
It is the responsibility of the grading contractor to comply with the requirements on
the grading plans as well as the local grading ordinance. All retaining wall and trench
backfill should be properly compacted. Geotechnical Exploration, Inc. will assume
no liability for damage occurring due to improperly or uncompacted backfill placed
without our observations and testing.
XII. LIMITATIONS
Our conclusions and recommendations have been based on available data obtained
from our field investigation and laboratory analysis, as well as our experience with
similar soils and formational materials located in this area of Carlsbad. Of necessity,
we must assume a certain degree of continuity between exploratory excavations
and/or natural exposures. It is, therefore, necessary that all observations,
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 38
conclusions, and recommendations be verified at the time grading operations begin
or when footing excavations are placed. In the event discrepancies are noted,
additional recommendations may be issued, if required.
The work performed and recommendations presented herein are the result of an
investigation and analysis that meet the contemporary standard of care in our
profession within the County of San Diego. No warranty is provided.
As stated previously, it is not within the scope of our services to provide quality
control oversight for surface or subsurface drainage construction or retaining wall
sealing and base of wall drain construction. It is the responsibility of the contractor
to verify proper wall sealing, geofabric installation, protection board installation (if
needed), drain depth below interior floor or yard surfaces, pipe percent slope to the
outlet, etc.
This report should be considered valid for a period of two (2) years, and is subject to
review by our firm following that time. If significant modifications are made to the
building plans, especially with respect to the height and location of any proposed
structures, this report must be presented to us for immediate review and possible
revision.
It is the responsibility of the owner and/or developer to ensure that the
recommendations summarized in this report are carried out in the field operations
and that our recommendations for design of this project are incorporated in the
grading and structural plans. We should be retained to review the project plans once
they are available, to verify that our recommendations are adequately incorporated
in them. Additional or modified recommendations may be issued if warranted after
plan review.
Proposed Lanshire Townhome Project
Carlsbad, California
Job No. 18-11968
Page 39
This firm does not practice or consult in the field of safety engineering. We do not
direct the contractor's operations, and we cannot be responsible for the safety of
personnel other than our own on the site; the safety of others is the responsibility of
the contractor. The contractor should notify the owner if any of the recommended
actions presented herein are considered to be unsafe.
The firm of Geotechnical Exploration, Inc. shall not be held responsible for
changes to the physical condition of the property, such as addition of fill soils or
changing drainage patterns, which occur subsequent to issuance of this report and
the changes are made without our observations, testing, and approval.
Once again, should any questions arise concerning this report, please feel free to
contact the undersigned. Reference to our lob No. 18-11968 will expedite a reply
to your inquiries.
Respectfully submitted,
GEOTECHNICAL EXPLORATION, INC.
Ji!!? ::i:fi
R.C.E. 34422/G.E. 2007
Senior Geotechnical Engineer
St~ect Geologist
Jon 1
P.G. .G. 2615
Se Geologist
VICINITY MAP
AQUA HEDIONDA
Thomas Guide San Diego County Edition pg 1106-ES
Lanshire Townhomes
SE Corner of Madison Street
and Oak Avenue
Carlsbad, CA.
LAGOON
Figure No. I
Job No. 18-11968
◄~-~
SURVEY CERTIFICATE
T0:$0Sl'lll)PfftlY1,1"1!A(Vl£NT.oHll(CU<IYllTU:C,OMP~'I':
=~~i~T(il01~!=~4io~:i1 ~~~~' :t~~Sll~"'~t ~~ ~fl-..J1.i'i~ ~& 10. 11-A. lf. It Nl(J 11 Of 1.0.81.E° ~~~~i,2.aitw.\ll
~ ~
ALTA / TOPOGRAPHIC SURVEY MADISON STREET
LEGAL DESCRIPTION ~~~rio1~Jl~~R:6F ~0~~1J~rru:1;•~t~J ;E,.?t~C:Nf;'':llJ'~oJ~i.r ~fcib ~~·rt:~Rf,.ifyAlf;~~A •.
:r~~!~~~:~:ioi~~N~E~ ~ ~ ~~!:i:~~~INgJ;l~L~ i:~8to'JE~~"° 1f~~~~ f~L~
APN: 204-031-01-00 6r 20,-0:51-02-00
1-<FFF,-.,>-r~Cf DWG;
IMAP N0.775
RFK!r.H MARK:
DESCRIPTION: 2.25 INCH DISK IN SOUTHEAST CORNER OF ORA!NA<.E BOX MARKED LS 8215
LOCA~: NClffHEAST CORNER Of CRANO AVE. ANO
WASHING'ltfrt ST., 52 FT. YitST OF RAILROAD tRACKS REcatt>: COUNTY OF SAN DIEGO nEVAllOH: 4.J.09 OATUii: 88
Fr.Al '" ,r0 1PTI ,.,.
LOTS 15 AND 18 IN BLOCK 47 OF MAP NO ns IN THE QTY Of CARLSBAD, COUNTY Of' • ' SAN 01£GO. STAlE OF CALIFORNIA.
SITE ADDRESS:
MADISON SlREtT CARLSBAD. CA 92008
APN
204-031-01 & 204-031-02
PREPARED FOR:
MICHAEi. KOOTCHICK
SOS PROPERTY MANAGEMENT 11855 SORRENTO VAl.l.EY ROAD, SUITE 523, SAN DIEGO, CA 92121
D~~D A h'I-RY·
ALTA CONSUI.TANTS 1283 EAST MAIN SlREET, SUITE 109 ,~~~a~· s92~~~101
~!'-~} 9)" 7!~;-8,~~~.
NnTFC::
1. 1HIS IS NOT A BOUNDARY SURVEY
2. 1HIS IS A Al.TA / TOPOGRAPHIC SURVEY ONI.Y 3. DIMENSIONS SH0'!,1,1 ARE PER RECORD DATA ONLY
ALTA CONSULTANTS PL&l't1fUfG DGDG&Jm(I) smtnY'DfG 12~ c;,.-r '°'""'" at'IIUT. sum: ,w. n. c;,.roro. -c.., uiiil~ .108 KO. 89&-UI DATDAVOUIT a, 9019
LEGEND:
1" INTERVAL CONTOURS ...
EX. SlRUCTURES.............. I~ __ __,
EX. CONCRETE ................. .
EX TREES, BUSHES ........ . * ~1) -: ~
£1.]_J.J-EX EDGE OF PAVING ....... .
EX. FENCE ....................... .
EX. OVERHEAD UTILITIES .. --OHU--
EX. LOT LINES ................. .
SITE BOUNDARY .............. ..
EX EASEMENT .................. .
ABBREVIATIONS:
TOP OF CURB ............ TC
EDGE OF PAVEMENT ••. EP
F'LOW UNE ................... Fl
BEGIN CURVE .............. BC
ENO CURVE •••••.•••••••••.. EC
18-11968-p.ai
TOP OF WALL ............ TW
BOTTOM Of WALL. ...... BTM
ANGLE P01NT .............. AP
TOP or BERM ............ :18 POWER POLE ............... PP
REFERENCE: This Plot Plan was prepared from an existing
TOPOGRAPHIC SURVEY MAP by ALTA CONSULTANTS
PLANNING ENGINEERING SURVEYING dated 8/2/2018
and from on-site field reconnaissance performed by GEi.
I
ss,n . .,,'.I-" .:,11-+
~ . .,.
C,
40•
I
GRAPHIC SCALE
10 I
( IN FEET)
i
Scale: l" = 20'
( approximate ) . _
<ii' ~
. ---f_Jii ----,-------"'-''Y,
--·----l.1'·--·· ,..,
C, ·~
~ ;,,·
·,jc -·-·
. __ , tJl ... , -. --.----··--··-
v' 't.
\
s-t-rs ~-ta& -+s,,-. .r-..,----•s,; ~• ,,
~ ~ ·Oo ·Oo..,__ ~ ~ "-
... J " ':> ···-·-··-• ·+ssi.a:··~ --·-·-+.s-,;··-------·--~'-----·-+s; ·----·-~---1 •00--11 · _. . +s
u •o9 •s6 ,:P ->', \ / :S:.r.,
, / .· s., S55'2~7.:;'o.,o·~w:....___ , 1>'>· <11 : ;· \ 'V
I
r
\
!"1/ ,<;:,. ~Ag;;;__;;> ♦ 5• WOOD FENCE ! '
., l':l!:J::::=::::Cl=:==i~=:2!:.:Q::==l~===lf~~Dc==~====il=='°'==~~R'==D=~d:JQ;,~'-c'!-C ~~ ! ~I . ill! .----+ ;J--~::.--.,,,=='"'""'li x.... .-1r,+,c----~
L9 iui <:,'l-~"' f -.:.,J :: ;!if,9 lf'h
LLI , 'i H • i. ,
g t 1:1
35'
(\-15' ·s~i-r.,
-tf,y
t·,
REFERENCE: This Plot Plan is not to be used for legal
purposes. Locationss and dimensions are approximate.
Actual property dimensions and locations of utilities
may be obtained from the Approved Building Plans
or the "As-Built" Grading Plans.
LEGE ND • INF-2
~HP-5
Qaf
. ~HAINLINK F¢;
+s. S,o6J.>
111!111: 110WN «Ii!= CMil.SIBAllll IMP MO. 775
Ulf14
llll.!111:11(47
Approximate Location of
Infiltration Test
Approximate Location
of Exploratory Handpit
Artificial Fill
Qop6_7 Old Paralic Deposits (units 6-7)
PLOT PLAN AND
SITE SPECIFIC
GEOLOGIC MAP
Lanshire Townhomes
SE Corner of Madison Street
and Oak Avenue
Carlsbad, CA.
Figure No. II
Job No. 18-11968
•
Geotechnical .., Exploration, Inc.
~ (September 2018)
ti (!)
...J ~ w
0 w (!)
~ 0.. (!) w a:: 5: (/J z ::i .,
<D ~
(!) g
z 0 ~ 0 ...J 0.. X w
/ EQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED
Hand Tools 2' X 2' X 2.9' Handpit 8-13-18
SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH LOGGED BY
± 53.75' Mean Sea Level Not Encountered JKH
FIELD DESCRIPTION ;g-
AND ii:::= ii::: 'n ~ ~ ~ ~ CLASSIFICATION w 0~ w Cl a. ci ~
~ wa:: ~~ ::a a:: ::a-~q + _j I!::
-' w ::::,~ en
I 0 -' DESCRIPTION AND REMARKS (/) 0::::> ::::, ::::, :z g I-::s I-::s u5 ::a I-::a--::a :s: z I-CD a.. (.) -en -en en-<( z a.. ::a ::a (Grain size, Density, Moisture, Color) (/) a..~ a..z I--~rl:i zo ~o o::::> w >--c% ,o zW a.. 0 ~~ _,o
0 en ::i ~::a _Cl o:::e :::eo W0 CD0
~~-SIL TY SAND , fine-to medium-grained, with SM r . some gravel. Loose. Dry. Gray-brown. -'o.~.-:
~J¥. FILL (Qaf) -~~ l~.
-1:~: ~-, .. 1 -SILTY SAND, fine-to medium-grained; poorly to SM
-moderately cemented. Medium dense to dense.
Dry to damp. Red-brown.
-OLD PARALIC DEPOSITS (Qop 6•7)
► -
2----iron nodules.
-
---22% passing #200 sieve. 8.3 125.8
-
~
3 -
-
-
-
-Bottom @2.9'
-
-
-
4 -
-
-
-
-
-
-
-
.Y. JOB NAME
PERCHED WATER TABLE Lanshire Townhomes
~ BULK BAG SAMPLE SITE LOCATION
[I] IN-PLACE SAMPLE SE Comer of Madison St. and Oak Ave., Carlsbad, CA
■ JOB NUMBER REVIEWED BY LDR/JAC LOG No. MODIFIED CALIFORNIA SAMPLE
0 NUCLEAR FIELD DENSITY TEST 18-11968 •r.= -~ HP-1 FIGURE NUMBER Exploratlon, Inc.
~ STANDARD PENETRATION TEST Illa ~ '--
""'
ci 0 wen -'W 0..I :::e:0 <Z en=
.J
<X) a
~
I-0 (!)
...J a. X w
0 w (!)
a: (!)
w a::
:i: (/) z :s
<X) g:
8 ...J z 0 ~ g a. X w
/ EQUIPMENT DIMENSION & TYPE OF EXCAVATION
Hand Tools 2' X 2' X 3' Handpit
SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH
± 54. 75' Mean Sea Level Not Encountered
-
-
-
-
-
-
2-
-
-
-
-
3
-
-
-
-
-
-
-
4 -
-
-
-
-
-
-
-
-' LU 0 -' a:, a.. ~ !
FIELD DESCRIPTION
AND
CLASSIFICATION
DESCRIPTION AND REMARKS
(Grain size, Density, Moisture, Color)
SIL TY SAND , fine-to medium-grained, with
some gravel. Loose. Dry. Gray-brown.
FILL (Qaf)
SIL TY SAND , fine-to medium-grained; poorly to
moderately cemented. Medium dense to dense.
Dry to damp. Red-brown.
OLD PARALIC DEPOSITS (Qop 6•7)
--iron nodules.
1 --23% passing #200 sieve.
Bottom @3'
JOB NAME
c.t:i <.:i c.t:i :::;
SM
SM
_y_ PERCHED WATER TABLE Lanshire Townhomes
~ BULK BAG SAMPLE SITE LOCATION
~ DATE LOGGED
8-13-18
LOGGED BY
JKH
~ :::s! 0
~c l >-c ~ c::i 0::: u Cl g_ c::i ~ LU Cl c.. LU d~ LU 0::: ~~ ::a:o::: :a:-i?: cj + _j b!:: :::, i?: (J) LU (J) (.):::, :::, :::, z 0 I--' LU :::s I-:::s u5 :a: I-:a:--:a: s:z -(J) -(J) (J)-<i: (J) 0..I a.. 5,2 a..z I--~ r5 zo a.. z o=> ::a:0 ,o • LU a.. 0 ~c X 0 _,o <i:z ~:a: ~Cl o::a: :a: Cl LU (.) a:, (.) (J)=
2.1
[TI IN-PLACE SAMPLE SE Comer of Madison St. and Oak Ave., Carlsbad, CA
■ JOB NUMBER REVIEWED BY LDR/JAC LOG No.
MODIFIED CALIFORNIA SAMPLE
0 NUCLEAR FIELD DENSITY TEST 18-11968 cr.;i-•kal HP-2 FIGURE NUMBER Exploration, Inc.
~ STANDARD PENETRATION TEST lllb ~ '-~
ti ('.)
...J a. [:i
0 w
I' EQUIPMENT DIMENSION & TYPE OF EXCAVATION
Hand Tools 2' X 2' X 2' Handpit
SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH
± 54.25' Mean Sea Level Not Encountered
I
I I-C... w Cl
-
-
-
2-
-
3 -
-
4 -
-
-
-
-
-
-
FIELD DESCRIPTION
AND
CLASSIFICATION
J wf-----------------------r----i g 1[ DESCRIPTION AND REMARKS u:i
~ ! (Grain size, Density, Moisture, Color)
SIL TY SAND , fine-to medium-grained, with
some gravel. Loose. Dry. Gray-brown.
FILL (Qaf)
SIL TY SAND , fine-to medium-grained; poorly to
moderately cemented. Medium dense to dense.
Dry to damp. Red-brown.
OLD PARALIC DEPOSITS (Qop d
--iron nodules.
Bottom @2'
(.)
u:i :::i
SM
SM
..,
DATE LOGGED
8-13-18
LOGGED BY
JKH
~ ::R
l >-c-~ ~= ~
0::: u Cl g_ ~ ci w Cl o. w ci b!:: ci-WO::: ~~ ::;;; 0::: ::;;;-~q + _j ::::,~ en wen (.) ::::, ::::, ::::, :z 0 I-JW :5 I-:5 ci5 ::;;; I-::;;;--::;;; s:z -en en_ <i:: en C... I c...~ -en ~m zo z o::::> ::;;;0 c...z I--c... •O . w c...O ~c X 0 JO <i::z ~::;;; ~Cl o::;;; ::;;; Cl w (.) (D(.) en=
<9L.--~-..J.-...L....-------------------....J...-..L--..J.---l...--..l..--~-......L.--..J.--....1...--J
~ ('.)
w Ct:
:i: (/)
~
"' lll
(') g
z 0 ~ g
a. X w '-
.Y
~
[I]
■
[}]
~
PERCHED WATER TABLE
BULK BAG SAMPLE
IN-PLACE SAMPLE
MODIFIED CALIFORNIA SAMPLE
NUCLEAR FIELD DENSITY TEST
STANDARD PENETRATION TEST
JOB NAME
Lanshire Townhomes
SITE LOCATION
SE Comer of Madison St. and Oak Ave., Carlsbad, CA
JOB NUMBER REVIEWED BY LDR/JAC LOG No.
18-11968 4r,,c:;&-" HP-3 FIGURE NUMBER Exploration, Inc.
Ille ~ ~
6 (!)
...J ~ w
@
,, EQUIPMENT DIMENSION & TYPE OF EXCAVATION
Hand Tools 2' X 2' X 2.5' Handpit
SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH
± 54.75' Mean Sea Level Not Encountered
~ ~ -' w ::c: 0 -' I-<D a.. a.. :a: :a: w >-c75 0 en
2-
-
-
3 -
-
-
4 -
FIELD DESCRIPTION
AND
CLASSIFICATION
DESCRIPTION AND REMARKS
(Grain size, Density, Moisture, Color)
SIL TY SAND , fine-to medium-grained, with
some gravel and brick. Loose. Dry. Gray-brown.
FILL (Qaf)
SIL TY SAND , fine-to medium-grained; poorly to
moderately cemented. Medium dense to dense.
Dry to damp. Red-brown.
OLD PARALIC DEPOSITS (Qop d
--iron nodules.
Bottom @ 2.5'
u:i (.)
c.ri ::::i
SM
SM
' DATE LOGGED
8-13-18
LOGGED BY
JKH
:,s! 0
fi== ~ i!'i:= ~ ci ~ i-: 0~ w 0 g_ ci c:i w :a:~ + ~ wa: ~~ :a: a: ~q _j WW (..) ::::> ::::> ::::> ::::>~ z 0 ~'z -'W :s~ :s ci5 :a: I-:a:--:a: -en -en en_ <( en a..::c: a..-a..z I--~ r5 zo a.. z o=> ::a:u ,o •w a..0 ~c X 0 -'o <CZ ~:a: ~Cl o::a: ::a:o w (..) <D (..) en=
(!)..___....,__....__....__ ___________________ ........ _....___....__ __ ...___..___ _ __.__........_ __ ....___ ........ __,
~ (!) w a:: :i: (/) z :5 co (0 ~
(!) g
z 0 ~ g
0.. X w -...
.Y
~
[I]
■
0
~
PERCHED WATER TABLE
BULK BAG SAMPLE
IN-PLACE SAMPLE
MODIFIED CALIFORNIA SAMPLE
NUCLEAR FIELD DENSITY TEST
STANDARD PENETRATION TEST
JOB NAME
Lanshire Townhomes
SITE LOCATION
SE Comer of Madison St. and Oak Ave., Carlsbad, CA
JOB NUMBER REVIEWED BY LDR/JAC LOG No.
18-11968 er, t:;l __,, HP-4 FIGURE NUMBER Exploratlon, Inc.
Hid ~ ~
a,
cl
21
ti 0
_J 0..
G'i
0 w
/ EQUIPMENT DIMENSION & TYPE OF EXCAVATION
Hand Tools 2' X 2' X 2.5' Handpit
SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH
± 55.5' Mean Sea Level Not Encountered
::c l-a... LJJ Cl
-
-
2 -
-
3 -
4-
-
-
_J LJJ 0 _J CD a... :a: :a: 1:, ;Ji
• •
FIELD DESCRIPTION
AND
CLASSIFICATION
DESCRIPTION AND REMARKS
{Grain size, Density, Moisture, Color)
SILTY SAND, fine-to medium-grained, with
some gravel. Loose. Dry. Gray-brown.
FILL (Qaf)
--tree roots up to 2" in diameter.
SIL TY SAND , fine-to medium-grained; poorly to
moderately cemented. Medium dense to dense.
Dry to damp. Red-brown.
OLD PARALIC DEPOSITS (Qop d
--iron nodules .
Bottom @ 2.5'
u5
c.j
u5 :::i
SM
SM
-...
DATE LOGGED
8-13-18
LOGGED BY
JKH
-~ 0 fi::= ~ >-c-~ ci c::: '-' Cl g_ i-: LJJ Cl -9, LJJ ci ci-LJJ c::: ~~ :a: c::: :a:~ ~q + _j b!c:
:::,~ en LJJ Cl) (.) :::, :::, :::, z 0 I--l LJJ ::i t:; ::i u5 :a: I-:a:--:a: en :§:Z a...::c -en -en en_ <( a...-a...z I--~z zo a... z o=> ::a:0 ,o ' LJJ a...0 ~c X 0 _,o ;Ji e. ~:a: ~Cl o::a: :a:~ LJJ (.) CD (.)
o.__ _ _.__...__......_ ___________________ _.__...__ ..... __ .___....__ _ ___.. _ __._ __ ..__...___,
-, 0.. (!) w (l'.'.
:i: (/J z :s a, ig
(!)
0 _J z 0 ~ 0 _J 0.. X w '-
.Y
~
[I]
■
[II
~
PERCHED WATER TABLE
BULK BAG SAMPLE
IN-PLACE SAMPLE
MODIFIED CALIFORNIA SAMPLE
NUCLEAR FIELD DENSITY TEST
STANDARD PENETRATION TEST
JOB NAME
Lanshire Townhomes
SITE LOCATION
SE Corner of Madison St. and Oak Ave., Carlsbad, CA
JOB NUMBER REVIEWED BY LDR/JAC LOG No.
18-11968 -~, G,_.nkal HP-5 FIGURE NUMBER Exploration, Inc.
Ille ~ ~
a,
0
0
i:i (!) ~ w LL
iii (!)
13 5
13 0
12 5
120
115
110
u Q.
~ 1i5 m 105
0
>-0::: 0
100
95
90
85
80
75
0
\
\
-I -..
5
\ ' \
\ \ ~
\ \ \
\ \
\ '
\ \ ' \ ' I\
' I\ .. \
\
I
I\
\
10
\
Source of Material HP-1 @2.0'
\ SIL TY SAND {SM}, Red-brown \ ' Description of Material
\
\ \ ASTM D1557 Method A
\ \ Test Method
\ \ \
I\ \
\ \
I\ \ 1
\ \ TEST RESULTS \ '
\ \ Maximum Dry Density 125.8 PCF
I\ \ ' Optimum Water Content 8.3 %
\ I\.
\ \ '
\ \ \ Expansion Index (El)
\ \
\ \ \
\ \ \
' I'\ " \ '\
I\ \ ~
\ 1\.
\ \ I\ Curves of 100% Saturation ' \ ' for Specific Gravity Equal to: \ I\ I\.
\ \ "' 2.80
\ \
\ I\ I\. 2.70
\ \ " I\ i, ' 2.60
\ l'I\. \
' I\ I\.
i\. '\ II,.
~ ' "I r--,,_ '\
\ t--. ' i\. I\.
I'-' \..
'\. '\ I',,.
" " "I
'\. " ......
'\ "' "'-..
" "" I"-" "" I"-. '\
"' ."
"' 15 20 25 30 35 40 45
0 ii:: ~t-----=-----=------------W.:...:..:....:AT.:..:E::.R:,.:C:.:O:.:.N:.:.T=:EN~T'...!.., .:::.%:...._ ______________ _J
!+ -~~.• Geotechnical MOISTURE-DENSITY RELATIONSHIP
z • ,., ., Exploration, Inc. Figure Number: IV
g Job Name: Lanshire Townhomes
~ Site Location: SE Corner of Madison St. and Oak Ave., C rlsb;
::;; 8 ___________________ ..1.J::.:o;,:b;.:N~u::.:,m~b;,;e;.:,r.;..: ..:,1.::,8·..:1:..:,1.::,96;;8:;;_ __________ .J
APPENDIX A
UNIFIED SOIL CLASSIFICATION CHART
SOIL DESCRIPTION
Coarse-grained (More than half of material is larger than a No. 200 sieve)
GRAVELS, CLEAN GRAVELS
(More than half of coarse fraction
is larger than No. 4 sieve size, but
smaller than 3")
GRAVELS WITH FINES
(Appreciable amount)
SANDS, CLEAN SANDS
(More than half of coarse fraction
is smaller than a No. 4 sieve)
SANDS WITH FINES
(Appreciable amount)
GW
GP
GC
SW
SP
SM
Well-graded gravels, gravel and sand mixtures, little
or no fines.
Poorly graded gravels, gravel and sand mixtures, little
or no fines.
Clay gravels, poorly graded gravel-sand-silt mixtures
Well-graded sand, gravelly sands, little or no fines
Poorly graded sands, gravelly sands, little or no fines.
Silty sands, poorly graded sand and silty mixtures.
SC Clayey sands, poorly graded sand and clay mixtures.
Fine-grained (More than half of material is smaller than a No. 200 sieve)
SILTS AND CLAYS
Liquid Limit Less than 50
Liquid Limit Greater than 50
HIGHLY ORGANIC SOILS
ML Inorganic silts and very fine sands, rock flour, sandy
silt and clayey-silt sand mixtures with a slight plasticity
CL Inorganic clays of low to medium plasticity, gravelly
clays, silty clays, clean clays.
OL Organic silts and organic silty clays of low plasticity.
MH Inorganic silts, micaceous or diatomaceous fine sandy
or silty soils, elastic silts.
CH Inorganic clays of high plasticity, fat clays.
OH Organic clays of medium to high plasticity.
PT Peat and other highly organic soils
APPENDIX B
INFILTRATION TEST DATA AND RATE
CALCULATIONS
Simple Open Pit Falling Head Test Sheet
Project Name: Lanshire Townhomes
Project No. 18-11968
Date Excavated: 10/4/18
Test Hole No: INF-1
Initial Time (Minutes) Final Time (Minutes)
1010 1100
1100 1200
1200 1300
Time interval
(minutes)
so
60
60
Initial Water Level
(inches)
27.750
28.000
28.000
Tested By: SO
Soil Classification: SM
Depth of Test Hole: 34"
Test Hole Dia: 24"
Final Water Level
(inches)
30.250
30.125
29.750
Change in water
(inches)
2.500
2.125
1.750
Falling Head Rate
(min/inches)
20.000
28.235
34.286
Simple Open Pit Falling Head Test Sheet
Project Name: Lanshire Townhomes
Project No. 18-11968
Date Excavated: 10/4/18
Test Hole No: INF-2
Initial Time (Minutes) Final Time (Minutes)
1020 1120
1120 1220
1220 1320
Time interval
(minutes)
60
60
60
Initial Water Level
(inches)
27.500
28.500
28.500
Tested By: SO
Soil Classification: SM
Depth ofTest Hole: 36"
Test Hole Dia: 24"
Final Water Level
(inches)
29.500
29.750
29.500
Change in water
(inches)
2.000
1.250
1.000
Falling Head Rate
(min/inches)
30.000
48.000
60.000
Simple Open Pit Rate to Infiltration Rate Conversion (Porchet Method)
Project Name: Lanshire Townhomes
Project No. 18-11968
Test Hole No: INF-1
Test EB Depth DeltaT Water Depth
No. (inches) (min) 1 (inches)
1 34 50 27.750
2 34 60 28.000
3 34 60 28.000
4
5
6
7
8
9
Calculated By: SO
Checked By:
Test Hole Dia: 24"
Date: 10/4/2018
Date:
Depth of Test Hole: 34"
Porchet Corrections
Infiltration rate=((delta h*60r)/(delta t*(r+2 h avg))
Water Depth hl h2 delta h havg
2 (inches) (inches) (inches) (inches) (inches)
30.250 6.250 3.750 2.500 5.000
30.125 6.000 3.875 2.125 4.938
29.750 6.000 4.250 1.750 5.125
r (radius) delta delta t*fr+2 h
(inches) h*60r avg)
12 1800 1100
12 1530 1312.5
12 1260 1335
Infiltration
rate (in/hr)
1.636
1.166
0.944
Simple Open Pit Rate to Infiltration Rate Conversion (Porchet Method)
Project Name: Lanshire Townhomes
Project No. 18-11968
Test Hole No: INF-2
Test EB Depth DeltaT Water Depth
No. (inches) (min) 1 (inches)
1 36 60 27.500
2 36 60 28.500
3 36 60 28.500
4
5
6
7
8
9
Calculated By: SO
Checked By:
Date: 10/4/2018
Date:
Test Hole Dia: 24" Depth of Test Hole: 36"
Porchet Corrections
Infiltration rate=((delta h*60r)/(delta t*(r+2 h avg))
Water Depth hl h2 delta h havg r (radius)
2 (inches) (inches) (inches) (inches) (inches) (inches)
29.500 8.500 6.500 2.000 7.500 12
29.750 7.500 6.250 1.250 6.875 12
29.500 7.500 6.500 1.000 7.000 12
delta
h*60r
1440
900
720
delta t*(r+2 Infiltration rate
have) (in/hr)
1620 0.889
1545 0.583
1560 0.462
I
Lanshire Townhomes Project 18-11968
Appendix I: Forms and Checklists
Categorization of Infiltration Feasibility Form I-8
Condition
Part t -full Infiltration feasibility SqccniAg Criteria
Would infiltration of the full design volume be feasible &om 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 O.S 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
The infiltration test results at the locations where testing was conducted on the site were 0.472 and 0.231 inches per hour with a
minimum factor of safety of 2 applied. Based on the infiltration rate findings below the locations, infiltration rates greater than 0.5
inches per hour were not encountered. Simple open pit testing was performed at 2 locations on the site in accordance with
Appendix D of the City of Carlsbad BMP design manual. In addition, a comprehensive evaluation of the site was conducted in
accordance with Appendix C.2.
Please refer to our "Report of Preliminary Geotechnical Investigation" dated October 10, 2018 for details of the comprehensive
evaluation and investigation conducted, simple open pit test rates and simple open pit rate to infiltration rate calculations and maps
representative of the study.
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 O.S 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:
The infiltration test results at the locations where testing was conducted on the site ranged from 0.472 to 0.231 inches per hour with
a minimum factor of safety of 2 applied. Based on the infiltration test rate findings below the locations, infiltration rates greater than
0.5 inches per hour were not encountered. Therefore, a narrative discussion of the associated geotechnical hazards that cannot be
mitigated to an acceptable level is not applicable.
Please refer to our "Report of Preliminary Geotechnical Investigation" dated October 4, 2018 for details of the comprehensive
evaluation and investigation conducted, simple open pit test rates and simple open pit rate to infiltration rate calculations and maps
representative of the study.
Summarize findings of studies; provide reference to studies, calculations, maps, data sources, etc. Provide narrative
discussion of study/ data source applicability.
I-3 February 2016
Lanshire Townhomes Project 18-11968
Appendix I: Forms and Checklists
Form 1-8 Page 3 of 4
Part 2-Partial Infiltration YI, No Infiltration Pcaaibility Screening Criteria
Would infiltration of water in any appreciable amount be physically feasible without any negative
consequences that cannot be reasonably mitigated?
Criteria
5
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.
Provide basis:
Yea No
X
The infiltration test results at the locations where testing was conducted at the site ranged from 0.472 to 0.231 inches per hour with
a minimum factor of safety of 2 applied. Based on our infiltration test rates and limited geotechnical investigation of the site, it is our
opinion that the soil and geologic conditions allow for partial infiltration rates. However, we recommend that the sidewalls of the
proposed basins be lined.
Please refer to our "Report of Preliminary Geotechnical Investigation• dated October 10, 2018 for details of the comprehensive
evaluation and investigation conducted, simple open pit test rates and simple open pit rate to infiltration rate calculations and maps
representative of the study.
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
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.
Provide basis:
X
In our opinion, any long term partial infiltration at the site will not result in geotechnical hazards which cannot be reasonable
mitigated to an acceptable level. However, we recommend that the sidewalls of the proposed basins be lined.
Please refer to our "Report of Preliminary Geotechnical Investigation• dated October 10, 2018 for details of the comprehensive
evaluation and investigation conducted, simple open pit test rates and simple open pit rate to infiltration rate calculations and maps
representative of the study.
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.
1-5 February 2016
Lanshire Townhomes Project 18-11968
Appendix I: Forms and Checklists
Factor of Safety and Design Infiltration Rate
Worksheet Form 1-9
Factor Category Factor Dcsaiption Assigned Factor Product (p)
Weight (w) Value (v) p=wxv
Soil assessment methods 0.25 2 0.5
Predominant soil texture 0.25 2 0.5
Suitability Site soil variability 0.25 2 0.5 A Assessment Depth to groundwater I impervious 0.25 2 0.5 layer
Suitability Assessment Safety Factor, SA = Ip 2.0
Level of pretreatment/ expected 0.5 sediment loads
B Design Redundancy/ resiliency 0.25
Compaction during construction 0.25
Design Safety Factor, Se = Ip
Combined Safety Factor, Srow= SAX Se
Observed Infiltration Rate, inch/hr, Ko1,,crve<1
(corrected for test-specific bias)
Design Infiltration Rate, in/hr, K.iongn = Kob,crved / Sro..i
Supporting Data
Briefly describe infiltration test and provide reference to test forms:
Simple open pit testing was performed at 2 locations on the site per the requirements of the City of Carlsbad Storm Water
Standards, BMP Design Manual, in acx:ordance with Appendix D.
Please refer to our "Report of Preliminary Geotechnical Investigation" dated October 10, 2018 for details of the
comprehensive evaluation and investigation conducted, simple open pit test rates and simple open pit rate to infiltration
rate calculations and maps representative of the study.
1-7 February 2016
APPENDIX C
USDA VVEB SOIL SURVEY MAP
3JO 9'3S'N
I
I
i
I
I
I
00
3JO 9'34"N ffl
3: !f: iii
~
3: !f: iii
~
=
467761
467761
N
A
Hydrologic Soil Group-San Diego County Area, California
(Lanshire Townhomes)
467769 ,em <167785 467793 4678)1 4678)9
467769 467rT7 <167785 467793 4678)1 4678)9
Map Salle: 1:359 if printed on A landscape (11" X 8,5'1 sheet ----=====--------========>Meiers 0 5 10 :10 ~ ----====-------<=======feet o IB ~ ro ro
Map projection: Web Mercatcr Comercoortlinates: WGS84 l:dgetics: UTM Zone UN WGS84
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
467817 467825
467817 467825
467833
467833
3: l;,
iii
~
3:
l;,
iii
~
I
I
i
I
I
I
10/10/2018
Page 1 of4
3JO 9' JS"N
3JO 9'34"N
Hydrologic Soil Group-San Diego County Area, California
(lanshire Townhomes)
MAP LEGEND MAP INFORMATION
Area of Interest (AOI) D Area of Interest (AOI)
Soils
Soll Rating Polygons
0 A
□ ND
D B
D BID
D C
0 CID
D D
D Not rated or not available
Soll Rating Lines
,,..,,, A
,,..,,, ND
,,..,,, B
,,..,,, BID
,,..,,, C
CID
,,..,,, D
,. ,, Not rated or not available
Soll Rating Points
■ A
■ ND
■ B
■ BID
USDA Natural Resources
aiii Conservation Service
■ C
CID
■ D
[J Not rated or not available
Water Features
,,,.._,, Streams and Canals
Transportation
+++ Rails
~ Interstate Highways
,,w, US Routes
Major Roads
Local Roads
Background
• Aerial Photography
Web Soil Survey
National Cooperative Soil Survey
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: San Diego County Area, California
Survey Area Data: Version 13, Sep 12, 2018
Soil map units are labeled (as space allows) for map scales
1 :50,000 or larger.
Date(s) aerial images were photographed: Nov 3, 2014-Nov
22,2014
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
10/10/2018
Page 2 of 4
Hydrologic Soil Group-San Diego County Area, California Lanshire Townhomes
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres lnAOI Percent of AOI
~
MIC Marina loamy coarse B 0.2
sand, 2 to 9 percent
slopes
Totals for Area of Interest 0.2
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (AID, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of 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.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These 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.
If a soil is assigned to a dual hydrologic group (AID, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
100.0%
100.0%
10/10/2018
Page 3 of4
Hydrologic Soil Group-San Diego County Area, California
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
~ Natural Resources
.-Conservation Service
Web Soil Survey
National Cooperative Soil Survey
Lanshire Townhomes
10/10/2018
Page 4 of4
APPENDIX D
USGS Design Maps Summary Report
Design Maps Summary Report
lilJSGS Design Maps Summary Report
User-Specified Input
Report Title Lanshire Townhomes
Tue October 9, 2018 23:37:44 UTC
Building Code Reference Document ASCE 7-10 Standard
(which utilizes USGS hazard data available in 2008)
Site Coordinates 33.1597°N, 117.3454°W
Site Soil Classification Site Class D -"Stiff Soil"
Risk Category I/II/III
USGS-Provided Output
Ss= 1.150g
S1 = 0.441 g
SMs = 1.196 g
SM1 = 0.687 g
Sos= 0.797 g
So1 = 0.458 g
sin M rcos
Escondido•
Page 1 of2
For information on how the SS and 51 values above have been calculated from probabilistic (risk-targeted) and
deterministic ground motions in the direction of maximum horizontal response, please return to the application and
select the "2009 NEHRP" building code reference document.
MCEa Response Spectrum Design Response Spectrum
,i u.7::? s •J.-IX
.,. (Jl•-, ~ ft,,.llt
Ptrl11d, T (KC)
For PGAM, TL, c.s, and c., values, please view the detailed report.
https://prod0l-earthquake.cr.usgs.gov/designmaps/us/summary.php?template=minimal&la... 10/9/2018
Design Maps Detailed Report
EIJSGS Design Maps Detailed Report
ASCE 7-10 Standard (33.1597°N, 117.3454°W)
Site Class D -"Stiff Soil", Risk Category I/II/III
Section 11.4.1 -Mapped Acceleration Parameters
Note: Ground motion values provided below are for the direction of maximum horizontal
spectral response acceleration. They have been converted from corresponding geometric
mean ground motions computed by the USGS by applying factors of 1.1 (to obtain Ss) and
1.3 (to obtain S,). Maps in the 2010 ASCE-7 Standard are provided for Site Class B.
Adjustments for other Site Classes are made, as needed, in Section 11.4.3.
From Figure 22-1 cii 5s = 1.150 g
From Figure 22-2 t21 s, = 0.441 g
Section 11.4.2 -Site Class
The authority having jurisdiction (not the USGS), site-specific geotechnical data, and/or
the default has classified the site as Site Class D, based on the site soil properties in
accordance with Chapter 20.
Table 20.3-1 Site Classification
--Site Class Vs Nor Nch Su
A. Hard Rock >5,000 ft/s N/A N/A
B. Rock 2,500 to 5,000 ft/s N/A N/A
C. Very dense soil and soft rock 1,200 to 2,500 ft/s >50 >2,000 psf
Page 1 of 6
D. Stiff Soil 600 to 1,200 ft/s 15 to 50 1,000 to 2,000 psf
E. Soft clay soil
F. Soils requiring site response
analysis in accordance with Section
21.1
<600 ft/s <15 <1,000 psf
Any profile with more than 10 ft of soil having the characteristics:
• Plasticity index PI> 20,
• Moisture content w 2:: 40%, and
• Undrained shear strength Su < 500 psf
See Section 20.3.1
For SI: lft/s = 0.3048 m/s llb/ft2 = 0.0479 kN/m 2
https://prod0 I-earthquake.er. usgs.gov/designmaps/us/report. php?template=minimal&latitu... 10/9/2018
Design Maps Detailed Report Page 2 of 6
Section 11.4.3 -Site Coefficients and Risk-Targeted Maximum Considered Earthquake
(MCER) Spectral Response Acceleration Parameters
Table 11.4-1: Site Coefficient F,
Site Class Mapped MCE • Spectral Response Acceleration Parameter at Short Period
Ss ::; 0.25 Ss = 0.50 Ss = 0.75 Ss = 1.00 Ss 2:: 1.25
A 0.8 0.8 0.8 0.8 0.8
B 1.0 1.0 1.0 1.0 1.0
C 1.2 1.2 1.1 1.0 1.0
D 1.6 1.4 1.2 1.1 1.0
E 2.5 1.7 1.2 0.9 0.9
F See Section 11.4. 7 of ASCE 7
Note: Use straight-line interpolation for intermediate values of Ss
For Site Class= D and Ss = 1.150 g, F, = 1.040
Table 11.4-2: Site Coefficient Fv
Site Class Mapped MCE • Spectral Response Acceleration Parameter at 1-s Period
s,::; 0.10 s, = 0.20 s, = 0.30 s, = 0.40 s, 2:: 0.50
A 0.8 0.8 0.8 0.8 0.8
B 1.0 1.0 1.0 1.0 1.0
C 1. 7 1.6 1.5 1.4 1.3
D 2.4 2.0 1.8 1.6 1.5
E 3.5 3.2 2.8 2.4 2.4
F See Section 11.4. 7 of ASCE 7
Note: Use straight-line interpolation for intermediate values of S,
For Site Class = D and S, = 0.441 g, Fv = 1.559
https ://prod0 I -earthquake.er. usgs. gov/ designmaps/us/report. php?ternplate=rninirnal&latitu... 10/9/2018
Design Maps Detailed Report
Equation (11.4-1): SMs = F.Ss = 1.040 X 1.150 = 1.196 g
Equation (11.4-2): SM1 = fvS1 = 1.559 X 0.441 = 0.687 g
Section 11 .4.4 -Design Spectral Acceleration Parameters
Equation (11.4-3): Sos=½ SMs = ½ X 1.196 = 0.797 g
Equation (11.4-4): S01 = ½ SMl = ½ X 0.687 = 0.458 g
Section 11.4.5 -Design Response Spectrum
From Figure 22-12 [l] TL = 8 seconds
j ·
6 l
l
l rr.
Figure 11.4-1: Design Response Spectrum
Si)I = 0.-158 --, ----------T ---------I
I I I
I I I
I
I
I
T,. = OJ J 5 Ts= 0.575 I .OOCl
T < T0 : s. = S08 ( 0.4 +0.6 T /T0 )
T0 :ST :S T8 : $1 = SD!i
T, < T :S TL: $1 = S0JT
Pniod, T Ut'l!I
Page 3 of 6
https://prod0 I -earthquake.er. usgs.gov / designmaps/us/report. php?template=minimal&latitu... 10/9/2018
Design Maps Detailed Report Page 4 of 6
Section 11.4.6 -Risk-Targeted Maximum Considered Earthquake (MCER) Response
Spectrum
The MCE. Response Spectrum is determined by multiplying the design response spectrum above by
1.5.
I
I
I
I
I
I
I
I
I
I
I
I
I s~,1 = o.687 -i---r --------I
Ta=0.115 Ts= 0.574
I
1.000
Pmod, T ((«I
https ://prod0 I -earthquake.er. usgs.gov I designmaps/us/report. php ?template=minimal&latitu... 10/9/2018
Design Maps Detailed Report Page 5 of 6
Section 11.8.3 -Additional Geotechnical Investigation Report Requirements for Seismic
Design Categories D through F
From Figure 22-7 [43 PGA = 0.456
Equation (11.8-1):
Table 11.8-1: Site Coefficient FeGA
Site Mapped MCE Geometric Mean Peak Ground Acceleration, PGA
Class
PGA !, PGA = PGA = PGA = PGA 2=
0.10 0.20 0.30 0.40 0.50
A 0.8 0.8 0.8 0.8 0.8
B 1.0 1.0 1.0 1.0 1.0
C 1.2 1.2 1.1 1.0 1.0
D 1.6 1.4 1.2 1.1 1.0
E 2.5 1.7 1.2 0.9 0.9
F See Section 11.4. 7 of ASCE 7
Note: Use straight-line interpolation for intermediate values of PGA
For Site Class = D and PGA = 0.456 g, feGA = 1.044
Section 21.2.1.1 -Method 1 (from Chapter 21 -Site-Specific Ground Motion Procedures
for Seismic Design)
From Figure 22-17 csi CRs = 0.941
From Figure 22-18 [&J CR1 = 0.993
https ://prod0 I -earthquake.er. usgs.gov I designmaps/us/report. php?template=minimal&latitu... 10/9/2018
Design Maps Detailed Report
Section 11.6 -Seismic Design Category
Table 11.6-1 Seismic Design Category Based on Short Period Response Acceleration Parameter
RISK CATEGORY
VALUE OF Sos
I or II III IV
Sos< 0.167g A A A
0.167g :S Sos < 0.33g B B C
0.33g :S Sos < 0.50g C C D
0.50g :S Sos D D D
For Risk Category= I and Sos= 0.797 g, Seismic Design Category= D
Table 11.6-2 Seismic Design Category Based on 1-S Period Response Acceleration Parameter
RISK CATEGORY
VALUE OF So,
I or II III IV
So,< 0.067g A A A
0.067g :S So, < 0.133g B B C
0.133g :S So,< 0.20g C C D
0.20g :S So, D D D
For Risk Category= I and So,= 0.458 g, Seismic Design Category= D
Note: When S, is greater than or equal to 0. 75g, the Seismic Design Category is E for
buildings in Risk Categories I, II, and III, and F for those in Risk Category IV, irrespective
of the above.
Seismic Design Category = "the more severe design category in accordance with
Table 11.6-1 or 11.6-2" = D
Note: See Section 11.6 for alternative approaches to calculating Seismic Design Category.
References
1. Figure 22-1:
Page 6 of 6
https ://earthquake. usgs.gov /hazards/designmaps/downloads/pdfs/2010_ASCE-7 _Figure_22-1. pdf
2. Figure 22-2:
https ://earthquake. usgs.gov /hazards/designmaps/downloads/pdfs/2010_ASCE-7 _Figu re_22-2. pdf
3. Figure 22-12:
https ://earthquake. usgs.gov /hazards/designmaps/downloads/pdfs/2010_ASCE-7 _Figure_22-12. pdf
4. Figure 22-7:
https ://earthquake. usgs.gov /hazards/designmaps/downloads/pdfs/2010_ASCE-7 _Figure_22-7. pdf
5. Figure 22-17:
https ://earthquake.usgs.gov /hazards/designmaps/downloads/pdfs/2010_ASCE-7 _Figure_22-17. pdf
6. Figure 22-18:
https ://earthquake. usgs.gov /hazards/designmaps/downloads/pdfs/20 lO_ASCE-7 _Figure_22-18.pdf
https ://prod02-earthquake.cr. usgs.gov I designmaps/us/report. php ?template=minimal&latitu... 10/9/2018