PGA West - Coral Mountain TR 34243 BCPR2021-0011 (Plan J-Mod & J) Geotechnical ReportEARTH SYSTEMS PACIFIC
Earth Systems________________________________________________
79‐811 Country Club Drive, Suite B | Bermuda Dunes, CA 92203 | Ph: 760.345.1588 | www.earthsystems.com
December 16, 2020 File No.: 300310‐002
Doc. No.: 20‐12‐712
Alta Verde Coral Mountain, LLC
PO Box 13290
Palm Desert, CA 92255
Attention: Mr. Russell Jones
Project: Coral Mountain Tract 34243 (aka Pasatiempo)
Avenue 58 West of Madison Street
La Quinta, Riverside County, California
Subject: Geotechnical Engineering Report Update
In accordance with your request, Earth Systems Pacific [Earth Systems] has reviewed the
referenced documents for the purpose of updating the soils reports and providing supplemental
recommendations in accordance with the 2019 California Building Code. Our conclusions and
recommendations are provided below. Additionally, please review the limitations section of this
report as the information presented is integral to the understanding of this document.
This report completes our scope of services in accordance with our Change Order No. 3 BD‐
10109‐06 with new File No.: 300310‐002, dated November 10, 2020. Unless requested in writing,
the client is responsible for distributing this report to the appropriate governing agency or other
members of the design team. We appreciate the opportunity to provide our professional
services. Please contact our offices if there are any question s or comments concerning this report
or its recommendations.
Respectfully submitted,
EARTH SYSTEMS PACIFIC
Anthony Colarossi
Project Engineer
CE 60302
Distribution: 4/Alta Verde Builders
1/Mr. Russell Jones (rjones@altaverdebuilders.com)
1/BER
BCPR2021-0011
CORAL MOUNTAIN / PLAN
J & J-MOD TRACT
CONSTRUCTION PLANS
07/21/2021
EARTH SYSTEMS PACIFIC
December 16, 2020
TABLE OF CONTENTS
Background .................................................................................................................... 1
Site Reconnaissance ........................................................................................................... 1
Field Exploration ................................................................................................................ 3
Laboratory Testing.............................................................................................................. 4
Collapse Potential ............................................................................................................... 4
Groundwater .................................................................................................................... 6
Ground Subsidence Due to Groundwater Withdrawal ........................................................ 8
Earthquake Settlement (2019 CBC) ..................................................................................... 9
Conclusions and Supplemental Recommendations ........................................................... 11
Site Development – Grading ............................................................................................. 11
Excavations, and Utilities .................................................................................................. 12
Foundations .................................................................................................................. 12
Seismic Design Criteria ..................................................................................................... 14
Retaining Walls ................................................................................................................ 15
Grading Observation and Testing ..................................................................................... 17
Limitations .................................................................................................................. 17
References .................................................................................................................. 19
Attachments: Vicinity Map
Exploration Map
Fault Parameters
Historic Faults
Terms and Symbols
Boring Logs
Site Specific
Liquefaction Settlement
Dry Seismic Settlement
Lab Results
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Background
This residential project’s soil report was first initiated in 2005 and grading operations for the 20‐
acre site was documented in our Report of Testing and Observations Performed During Grading
(Earth Systems, 2007). The original Tract Map 34243 shows 70 numbered lots and 13 lettered
lots. Based on a historical aerial photo review (Google 2020) found in Section “Site
Reconnaissance”, construction of individual homes completed varied between years of 2008 and
2015. Note aerial photos were not available for the years 2007 and 2008 where some homes
noted on the 2009 aerial photo may have been completed earlier.
Based on client information, a site visit and google aerial review, there are a remaining 40
residential homes to be constructed, see bounded red borderline in Figure 1. The infrastructure
appears to be completed. This report contains additional explorations that were conducted to
study possible groundwater influence by nearby groundwater recharge ponds located
approximately 6,300 linear feet south of this project. Review of reports of nearby projects
indicated groundwater was rising between 2008 and 2016. The groundwater readings were
published for wells located near the Trilogy Resort in La Quinta, California. For additional
information on groundwater levels, please see the section “Groundwater” in this report.
Site Reconnaissance
Earth Systems personnel visited the site on November 11, 2020. During our site visits, site
conditions were visually observed and a summary of our findings of our site visit are presented
below.
In general, the site appeared in relatively good shape with no significant distress noted;
Vacant pads appeared in relatively good shape with little erosion damage;
Vacant pads were walked and did not find significant cracking along the pads. Green
erosion preventive sealant was still visible on the pads;
Asphalt pavement had traverse and longitudinal cracking, typical of aged pavement in the
hot desert climate.
o One measurement was 30 feet wide.
o Some cracks though appeared wide at 1 inch;
o Traverse and longitudinal cracks appeared to be filled in with sealant;
o It was noted that traverse cracks of the asphalt did not continue through the curb
and gutter nor interlocking pavers.
o From the information above, Earth Systems believes the cracking is caused by heat
and cooling due to the desert environment.
Walls along the south, west, and lots 17 to 19 were visually observed and appeared in
good shape with little cracking and only hairline width cracks if found;
Depressions at the surface of the column making up the fence/wall dividing between pads
26 to 30 and the retention basin located in the middle of the project was noted;
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The basin has slopes with retaining walls. The height of basin slopes were measured at
approximately 4 to 5 feet between bottom of basin and top of pads;
Basins looked in good shape and clean as if no flooding occurred, see Photo 7 and 8. Photo
7 shows an underground drainage system. The slopes soil surface within the basin
appeared to be soft or very loose. However, the slopes have well grown landscaping
covering the majority of the slope surface;
Slopes along the perimeter of the project (south, west, and lots 17 to 19) looked, in
general, in good shape with little erosion issues. Slopes are descending into the project;
Residential homes observed during the walks looked in very good condition from the
street distance;
Flatwork, including driveways, C&G, ditch aprons, and sidewalks, at various locations
looked in good condition; and
Drainage is based on sheet flow to the street and then to street inlets to underground
piping to the basin is assumed.
Figure 1 Thick Line Shows Location of Vacant Lots (40 total residential lots).
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Field Exploration
Exploratory Borings
Two exploratory borings were drilled to depths approximately 51½ feet below the existing
ground surface to observe soil profiles, ground water, and obtain samples for laboratory testing.
The borings were drilled on December 2, 2020, using a 8‐inch outside diameter hollow‐stem
auger. Augers were powered by a Mobile B‐61 truck‐mounted rubber‐tired drill rig
subcontracted by Cal Pac out of Calimesa, California. The boring locations are shown on the
Exploration Location Map, Plate 2, in the back of this report. The locations shown are
approximate, established by pacing and line‐of‐sight bearings from adjacent landmarks and
consumer grade GPS coordinates (+/‐ 15 feet). Refusal was not encountered to a depth of 51‐1/2
feet bgs but groundwater was discovered in boring B‐2 at a depth of approximately 49 feet below
the ground surface.
A representative from Earth Systems maintained a log of the subsurface conditions encountered
and obtained samples for visual observation, classification and laboratory testing. Subsurface
conditions encountered in the borings were categorized and logged in general accordance with
the Unified Soil Classification System [USCS] and ASTM D 2487 and 2488 (current edition). Our
typical sampling interval within the borings was approximately every 2½ to 5 feet to the full depth
explored; however, sampling intervals were adjusted as needed depending on the materials
encountered onsite. Samples were obtained within the test borings using a Standard Penetration
[SPT] sampler (ASTM D 1586) and a Modified California [MC] ring sampler (ASTM D 3550 with
those similar to ASTM D 1586). The SPT sampler has an approximate 2‐inch outside diameter
and a 1.38‐inch inside diameter. The MC sampler has an approximate 3‐inch outside diameter
and a 2.4‐inch inside diameter.
Both the ring and SPT samplers were mounted on drill rod and driven using a rig‐mounted 140‐
pound automatic hammer falling for a height of 30 inches. The number of blows necessary to
drive either a SPT sampler or a MC type ring sampler within the borings was recorded.
Design parameters provided by Earth Systems in this report have considered an estimated 72%
hammer efficiency based on data provided by the drilling subcontractor. The number of blows
necessary to drive either a SPT sampler or a MC type ring sampler within the borings was
recorded. Since the MC sampler was used in our field exploration to collect ring samples, the N‐
values using the California sampler can be roughly correlated to SPT N‐values using a conversion
factor that may vary from about 0.5 to 0.7. In general, a conversion factor of approximately 0.63
from the recent study at the Port of Los Angeles (Zueger and McNeilan, 1998 per SP 117A) is
considered satisfactory. A value of 0.63 was applied in our calculations for this project.
Bulk samples of the soil materials were obtained from the drill auger cuttings, representing a
mixture of soils encountered at the depths noted. Following drilling, sampling, and logging the
borings were backfilled with native cuttings and tamped upon completion. Our field exploration
was provided under the direction of a registered Geotechnical Engineer from our firm.
The final logs of the borings represent our interpretation of the contents of the field logs and the
results of laboratory testing performed on the samples obtained during the subsurface
exploration. The final logs are included in Appendix A of this report. The stratification lines
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represent the approximate boundaries between soil types, although the transitions may be
gradual. In reviewing the logs and legend, the reader should recognize the legend is intended as
a guideline only, and there are a number of conditions that may influence the soil characteristics
observed during drilling. These include, but are not limited to cementation, variations in soil
moisture, presence of groundwater, and other factors.
The boring logs present field blowcounts per 6 inches of driven embedment (or portion thereof)
for a total driven depth attempted of 18 inches. The blowcounts on the logs are uncorrected (i.e.
not corrected for overburden, sampling, etc.). Consequently, the user must correct the
blowcounts per standard methodology if they are to be used for design and exercise judgment
in interpreting soil characteristics, possibly resulting in soil descriptions that vary somewhat from
the legend.
Laboratory Testing
Samples were reviewed along with field logs to select those that would be analyzed further.
Those selected for laboratory testing include soils exposed and used during grading and those
deemed to be within the influence of the proposed structures. Test results are presented in
graphic and tabular form in Appendix B of this report. The tests were conducted in general
accordance with the procedures of the American Society for Testing and Materials [ASTM] or
other standardized methods as referenced below. Our testing program consisted of the
following:
Density and Moisture Content of select samples of the site soils collected (ASTM D
2937 & 2216).
Maximum density tests to evaluate the moisture‐density relationship of typical
soils encountered (ASTM D 1557).
Particle Size Analysis to classify and evaluate soil composition. The gradation
characteristics of selected samples were made by percent passing the #200 sieve
and sieve analysis procedures (ASTM D 1140).
Consolidation (Collapse Potential) to evaluate the compressibility and
hydroconsolidation (collapse) potential of the soil upon wetting (ASTM D 5333 and
D 2435).
Collapse Potential
Earth Systems further evaluated collapse potential at the site. Collapsible soil deposits generally
exist in regions of moisture deficiency. Collapsible soils are generally defined as soils that have
potential to suddenly decrease in volume upon increase in moisture content even without an
increase in external loads. Soils susceptible to collapse include loess, weakly cemented sands
and silts where the cementing agent is soluble (e.g. soluble gypsum, halite), valley alluvial
deposits within semi‐arid to arid climate, and certain granite residual soils above the
groundwater table. In arid climatic regions, granular soils may have a potential to collapse upon
wetting. Collapse (hydroconsolidation) may occur when the soils are lubricated or the soluble
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cements (carbonates) in the soil matrix dissolve, causing the soil to densify from its loose
configuration from deposition.
The degree of collapse of a soil can be defined by the Collapse Potential [CP] value, which is
expressed as a percent of collapse of the total sample using the Collapse Potential Test (ASTM
Standard Test Method D 5333). Based on the Naval Facilities Engineering Command (NAVFAC)
Design Manual 7.1, the severity of collapse potential is commonly evaluated by the following
Table 1, Collapse Potential Values.
Table 1
Collapse Potential Values
Collapse Potential Value Severity of Problem
0‐1% No Problem
1‐5% Moderate Problem
5‐10% Trouble
10‐20% Severe Trouble
> 20% Very Severe Trouble
Table 1 can be combined with other factors such as the probability of ground wetting to occur
on‐site and the extent or depth of potential collapsible soil zone to evaluate the potential hazard
by collapsible soil at a specific site. A hazard ranking system associated with collapsible soil as
developed by Hunt (1984) is presented in Table 2, Collapsible Soil Hazard Ranking System.
Table 2
Collapsible Soil Hazard Ranking System
Degree of Hazard Definition of Hazard
No Hazard No hazard exists where the potential collapse magnitudes are non‐
existent under any condition of ground wetting.
Low Hazard Low hazards exist where the potential collapse magnitudes are small
and tolerable or the probability of significant ground wetting is low.
Moderate Hazard
Moderate hazards exist where the potential collapse magnitudes are
undesirable or the probability of substantial ground wetting is low,
or the occurrence of the collapsible unit is limited.
High Hazard High hazard exists where potential collapse magnitudes are
undesirably high and the probability of occurrence is high.
The results of collapse potential tests performed on 3 selected samples from depths ranging from
10 to 35 feet below the ground surface indicated a collapse potential on the order of 0.2 to 0.9
percent. The goal of the collapse testing was to identify soils and densities where the potential
for collapse decreased to accepted levels. This accepted level is defined as where on‐site soils
had collapse potential less than 1% to 2% or the estimated relative compaction is greater or equal
to 85%, which is the typical standard of care based on the above Table 1 (1%) or where soil
collapse becomes a concern for structural soils (2%) (County of Los Angeles, 2013). Based on the
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above criteria and our field and laboratory findings, we estimate there is a “Low” collapse
potential from soil layers between 10 to 35 ft bgs.
Groundwater
Earth Systems used four methods to estimate the groundwater elevations: field exploration,
nearby well readings, and historic groundwater map.
Field Exploration: Both current borings reached a depth of 51½ feet below the ground surface
(bgs). Free groundwater was encountered in boring B‐2 at a depth of approximately 49 feet bgs,
but groundwater was not encountered at B‐1. Deeper exploration was not conducted at boring
B‐2, so the distinction between a perched water condition and “normal” groundwater condition
caused by a rising groundwater could not be verified; however, these levels seem consistent with
rising levels in the general area.
Nearby Well Information: Earth Systems found one California Department of Water Resources
well located approximately ½ mile east of the intersection of Monroe Street and Avenue 60 and
being called 336145N1162237W001. The well is located downstream of the project and
recharging ponds based on surface topography. Well monitoring data shows readings taken
between December 2011 to June 2020 (see Figure 2 below). The well has a surface elevation of ‐
81.5 feet and the ground water readings ranged in elevation from ‐135.15 to ‐106.15 feet, which
equates to a depth below the ground surface (bgs) from 53.6 to 24.6 feet bgs. The project surface
is found at approximately minus forty (‐40) feet Mean Sea Level (msl).
Figure 2 Well 336145N1162237W001
From the graph shown in Figure 2 above, there appears an increase in groundwater elevation.
Based on the well data and averaging each year’s data, Earth Systems used regression analysis
to estimate the potential for future years groundwater rise or decline at the well site based on
the well data. As shown in Figure 3, a slight rise in groundwater was observed and projected out
for 12 years, which will have the groundwater elevation reach the top of the well having an
elevation of ‐81 feet. Please note however, Coachella Valley Water District (CVWD) has
information of existing tile drains constructed in the past to control upper groundwater (two
aquifers can exist in this general area) from reaching elevations that could damage agricultural
production (see Section: Research of Tile Drain System below). Figure 3’s well data also shows a
drop in groundwater between 2015 and 2020. This information could indicate the tiles drains or
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CVWD control of the recharge ponds is maintaining the groundwater elevation below the ‐100
elevation at the well site.
Groundwater based on No Groundwater Rise from Well Data Figure 2 (No Head on Subsurface
Drainage): Based on the well’s groundwater elevation ‐106.1 feet and projecting that depth to
groundwater at the project site, the groundwater is approximately 66 feet below the ground
surface (106‐40). This is only an estimate and does not include a possible head of water that may
exist since information of the subsurface drainage moves toward the southeast or from the
project toward the Salton Sea.
Groundwater based on Groundwater Rise from Well Data Figure 2 (No Head on Subsurface
Drainage): Trendline information was used to estimate groundwater depth at the project for
determining liquefaction settlement, lateral spreading, groundwater seepage and other parts of
this report. Based on the regression analysis, we estimate the groundwater elevation at the well
will be at the wells ground surface in 12 years and that ground surface is ‐81 ft MSL. Therefore,
the groundwater will be 41 feet below the ground surface at Coral Mountain (81‐40).
1. Coral Mountain’s historic WSE was stated to be 30 feet below the ground surface.
Assuming the ground surface is ‐40 feet MSL, the WSE is ‐70 feet MSL (Earth Systems,
2005).
2. Based on the well data’s surface at ‐81 and this being achieved in 12 years, the depth
of groundwater at Coral Mountain will be approximately 40 feet bgs.
Figure 3 Yearly Averaged Data for Groundwater Readings and Projected Rise for 25 years.
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Research of Coachella Valley Water District Groundwater Level Increases and Tile Drain System:
Subsurface tile drainage systems were installed in the 1950s to control the upper high‐water
table conditions in the lower Coachella Valley and to intercept poor quality return flows (CVWD,
2012, pp 4‐5), see Figure 4. Subsurface agricultural tile drains are typically buried at depths
between 5 and 10 feet below ground which collects shallow saline groundwater and conveys it
to the Salton Sea (pp 6‐41). The District operates and maintains a collector system of 166 miles
of pipe. All agricultural drains empty into the Coachella Valley Stormwater Channel (CVSC) except
those at the southern end of the Valley, which flow directly to the Salton Sea (4‐5). Based on a
CVWD map showing drainage and storm outlet systems, (CVWD,1965), a drain line called “West
Drain Line” was constructed at the intersection of Avenue 58 and Madison and runs easterly to
additional drain lines. On a communications call with CVWD, Earth Systems was informed that
the drainage line located on public roadways, like Avenue 58, are sealed, but the drain tiles
located on private property (used for controlling high groundwater for agricultural purpose are
open. The District indicated that they have no authority on private property to prevent the
removal of tile drains. From the CVWD WMP (pp 4‐33), estimated flows to the Salton Sea shows
that drainage water initially increases while the East Valley is gaining storage. However, as growth
occurs and pumping increases, tile drainage decreases in response to declining groundwater
levels. The District does have some control of the groundwater levels based on the 2012
condition of the drainage systems, but the accuracy of a final groundwater table at the project
cannot be confirmed yet based on information contained.
Figure 4 CVWD Provided Drawing Showing Drain Lines
Ground Subsidence Due to Groundwater Withdrawal
As stated in the 2011 update report (Earth Systems, 2011), the project is in a Subsidence Study
Area called La Quinta Area 3. Since 1996, the USGS has been investigating regional land
subsidence in the Coachella Valley. The areas of subsidence coincide with localized ground‐
water‐level declines due to overdraft. The USGS suggests that t his documented subsidence is due
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to aquifer‐system compaction. They go on to state that “the subsidence may also be related to
tectonic activity in the valley.” A review of the USGS data indicates that the project site is at the
southeastern margin of the La Quinta (Area 3) zone. While the reported areal subsidence is
approximately 40 to 60 mm, the site is at the margin of the subsidence area, which can result in
an area of greater tensional stress and possible surface manifestation of earth fissures. It is our
opinion, and that of the City of La Quinta that, while predicting the location of surface ground
ruptures as a result of fissuring is difficult to impossible, the potential hazards from fissuring and
continued subsidence should be mitigated. While, to date, no evidence of fissuring has been
noted on the project site, the potential of damage from fissuri ng exists and has been documented
in this portion of the Coachella Valley.
The foundations and structures should be designed to accommodate this possible settlement as a
means of mitigating the hazard for life‐safety. The recommendations that follow are based on “very
low” expansion category soils.
Changes in pumping regimes can affect localized groundwater depths, related cones of
depression, and associated subsidence such that the prediction of where fissures might occur in
the future is difficult. In the event of future nearby aggressive groundwater pumping and
utilization, the occurrence of deep subsidence cannot be ruled out. Changes in regional
groundwater pumping could result in areal subsidence. The risk of areal subsidence in the future
is more a function of whether groundwater recharge continues and/or over‐drafting stops, than
geologic processes, and therefore the risk cannot be predicted or quantified from a geotechnical
perspective. The local water agencies are aware of the groundwater withdrawal subsidence
caused by past pumping regimes. Soil improvement recommended within can reduce the
potential for subsidence distress. As the degree of continued groundwater pumping, pumping
patterns, and their combined effect on the overlying soils is unknown, we believe it is prudent
for future homes to utilize a stiffened foundation to reduce the potential for distress due to
differential settlement until the risk from areal subsidence is more fully understood.
Earth Systems reviewed Riverside County GIS information (Riverside County Transportation and
Land Management Agency, 2017). The County of Riverside Parcel Report for this site has a
subsidence designation of “Active”.
Earthquake Settlement (2019 CBC)
Soil Liquefaction and Lateral Spreading: Liquefaction is the loss of soil strength from sudden
shacking (usually earthquake shaking), causing the soil to become a fluid mass. Liquefaction
describes a phenomenon in which saturated soil loses shear strength and deforms as a result of
increased pore water pressure induced by strong ground shaking during an earthquake.
Dissipation of the excess pore pressures will produce volume changes within the liquefied soil
layer, which can cause settlement. Shear strength reduction combined with inertial forces from
the ground motion may also result in lateral migration (lateral spreading). Factors known to
influence liquefaction include soil type, structure, grain size, relative density, confining pressure,
depth to groundwater, and the intensity and duration of ground shaking. Soils most susceptible
to liquefaction are saturated, loose sandy soils and low plasticity clay and silt.
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In general, for the effects of liquefaction to be manifested at the surface, groundwater levels
must be within 50 feet of the ground surface and the soils within the saturated zone must also
be susceptible to liquefaction. We consider the potential for liquefaction to occur at this site as
moderate to high because historic groundwater is generally less than 50 feet below the ground
surface. In a previous section, “Groundwater” we found the historic groundwater is estimated at
30 feet below the ground surface. We used a Magnitude Earthquake of 8.2 on the San Andreas
Fault Zone having a peak ground acceleration of 0.63g. Liquefaction output considering historic
groundwater levels are presented in Appendix A for current exploration B‐2, which appeared to
be the highest settlement for liquefaction. For three deep borings (current and past exploration),
results indicate a liquefaction settlement at depths greater than 30 feet are estimated to range
between 1⅝ to 1¾.
Dry Seismic Settlement: As will be discussed in a proceeding section called “Seismic Design
Criteria”, the 2019 Building Code procedures finds the design seismic acceleration has increased
at the project site: previously 0.48g and now 0.63g. The amount of dry seismic settlement is
dependent on relative density of the soil, ground motion, and earthquake duration. In
accordance with current CGS policy (Earth Systems discussion with Jennifer Thornburg, CGS May
2014), we used a site peak ground acceleration of ⅔ PGAM and an earthquake magnitude of 8.2
to evaluate dry seismic settlement potential. The peak ground acceleration values were obtained
from the OSHPD Seismic Design Maps on November 20, 2020.
Based upon methods presented by Tokimatsu and Seed (1987) and our current 2020 exploration
and analysis, the potential for seismically induced dry settlement of soils above the groundwater
table for the full soil column height (30 feet) was estimated to range between ⅛ to ¼ inch. For
the original soils report, the dry settlement is estimated to be approximately ⅜ inch using the
2005 boring log and current seismic information. This estimate is based on the current conditions
for B‐1 and B‐2 explored in 2020. Based on Special Publication 117 (2008), the calculated
differential settlement is estimated to be approximately half of the total dry seismic settlement.
The combination (seismic and loading) for total and differential settlements is addressed in a
later Section of this report.
Vertical Settlement from Liquefaction and Dry Seismic Analysis: Due to the general uniformity of
the soils encountered, seismic settlement is expected to occur on an areal basis and as such per
Special Publication 117A (CGS, 2008). For the combination of liquefaction and dry seismic
settlements, Earth Systems estimates boring B‐2 explored during our 2020 exploration
represents the maximum settlement. The combined settlement for B‐2 is 1⅞ inches. The
differential settlement is estimated to be approximately ½ of the total combined settlement for
liquefaction and dry seismic settlement. Half of the total which is approximately 1 inch, and this
considers the current soil conditions for boring B‐2.
Lateral Spreading: The potential for liquefaction induced lateral spreading under the proposed
project is considered low due to the fact liquefaction is estimated to occur deeper than 30 feet
below the ground surface. Based on a well‐known and practiced study (Bartlett and Youd, 2002)
lateral spreading is typically considered for liquefied layers occurring at depths between ground
surface and 30 feet below the ground surface. Onsite basins are also shallow.
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Conclusions and Supplemental Recommendations
Based upon our review of the referenced reports in light of the requirements of the 2019
California Building Code, it is our opinion that the recommendations provided in the project
geotechnical (soils) reports referenced above, remain applicable to the proposed project;
however, updated recommendations are provided below and supersede the referenced
geotechnical report recommendations as applicable. Earth Systems has not reviewed the project
grading plans or structural plans but should for geotechnical conformance.
Geotechnical Constraints and Mitigation:
Based on 2019 California Building Code seismic design procedures, the acceleration at the
site has increased.
Dry seismic settlement was reanalyzed.
Groundwater was anticipated in this report to reach the historic groundwater level of 30
feet below the ground surface.
Liquefaction settlement at this site was estimated for the historic groundwater return.
Site Development – Grading
A representative of Earth Systems should observe site clearing, grading, and the bottoms of
excavations before placing fill. Local variations in soil conditions may warrant increasing the
depth of recompaction and over‐excavation. The building pad areas should be precise graded by
removing any organic growth from the pad surface. The pad surface should be prepared and
verified to have a minimum relative compaction of 90% (ASTM D 1 557) at near optimum moisture
content. If the grade is to be raised from its current elevati on, non‐expansive granular fills should
be placed in maximum 8‐inch lifts (loose) and be compacted to at least 90% relative compaction
(ASTM D 1557) near its optimum moisture content prior to the placement of subsequent lifts. If
the pad is to be lowered in elevation and depending upon the depth of cut (if any), additional
over‐excavation and compaction may be required such that an adequate depth of fill is present
below foundation areas. Soils can be readily cut by normal grading equipment.
Recommendations provided in the Geotechnical Engineering Report by Earth Systems dated May
18, 2005 remain valid. Each lot development, site plans should be reviewed by the geotechnical
consultant relative to lateral extent of foundations, depth of foundations, basements, and
hardscaping to confirm validity.
Surcharge Load Restrictions: No fill or other surcharge loads shall be placed adjacent to any
building or structure unless such building or structure is capable of withstanding the additional
loads caused by the fill or the surcharge. Existing footings or foundations that will be affected by
any excavation shall be underpinned or otherwise protected against settlement and shall be
protected against detrimental lateral or vertical movement, or both.
Exception: Minor grading for landscaping purposes shall be permitted where done
with walk‐behind equipment, where the grade is not increased more than 1 foot from
original design grade or where approved by the building official.
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Excavations, and Utilities
Where excavations will reduce support from any foundation, a registered design professional
shall prepare an assessment for the structure as determined from examination of the structure,
the review of available design documents and, if necessary, excavation of test pits. The registered
design professional shall determine the requirements for underpinning and protection and
prepare site‐specific plans, details and sequence of work for submission. Such support shall be
provided by underpinning, sheeting and bracing, or by other means acceptable to the building
official.
Foundations
Structural Slab Foundations or Conventional Reinforced and Tied Together Shallow
Foundations
The foundations and structures should be designed to accommodate the estimated settlements as
a means of mitigating the hazard for life‐safety. The recommendations that follow are based on
“very low” expansion category soils.
Foundation Design: In our professional opinion, structures should be founded on a structural slab
using either conventionally reinforced and tied shallow foundation (grade beam), post‐tensioned,
or similar thickened or waffle slab (or similar), designed to accommodate the estimated differential
settlement of 2 inches in a 40‐foot span (1:240 distortion ratio). Foundations should be bearing on
a zone of properly prepared and compacted soils placed as recommended above under “Site
Grading”.
Foundation design of widths, depths, and reinforcing steel are the responsibility of the Structural
Engineer, considering the structural loading and the geotechnical parameters given in this report. A
minimum footing depth of 12 inches below lowest adjacent grade should be maintained. A
representative of Earth Systems should observe foundation excavations before placement of
reinforcing steel or concrete. Loose soil or construction debris should be removed from footing
excavations before placement of concrete. Foundation and grading plans should be reviewed to
confirm adequate fill thickness below foundations (2 feet typical).
Allowable Bearing Pressure: Allowable soil bearing pressures are given below for foundations
bearing on recompacted soils as described above. Allowable bearing pressures are net (weight of
footing and soil surcharge may be neglected).
1500 psf for dead plus design live loads. No allowable increases are permitted.
The allowable bearing value indicated is based on the anticipated maximum loads stated in the
referenced reports. If the anticipated loads exceed these values, the geotechnical engineer must
reevaluate the allowable bearing values and the grading requirements.
Modulus of Subgrade Reaction: Structural mat rigidity can be estimated by using a modulus of
subgrade reaction (ks1) of 200 pci for the underlying subgrade. Static elastic settlements of
foundations can be estimated using an effective modulus of subgrade reaction (kb) that is
December 16, 2020 ‐ 13 ‐ File No.: 300310‐002
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dependent on the effective width (b) of the foundation, where kb = ks1 [(b+1)/2b]2 and “b” equals
the foundation width in feet.
The estimated elastic settlement is then equal to the effective bearing pressure (qe) in psi divided
by kb. The effective bearing pressure (qe) may be computed as total design load divided by the
effective bearing area.
Estimated Settlements for Shallow Foundations based on Static Loading: Based on the project
soils report, Earth Systems estimated a total settlement less than 1 inch based on static loading
settlement. Differential settlement from this settlement condition is estimated as approximately
¾ inch of the total settlement. As such, considering differential settlement for the settlement
condition (Static Loading) applied over a typical foundation distance of 40 feet, the angular
distortion (1:480) meets the allowable 1:480 (Riverside County, 2003).
Earth Systems should review the foundation plan to review and analyze the actual distortion
angles. The structural engineer should submit the plans and column and wall loading for review
and analysis.
Estimated Settlements for Shallow Foundations based on All Settlements including Seismic: We
estimated a total settlement of approximately 2⅞ inches based on static loading and dry and
liquefaction seismic settlements. Differential settlement from both conditions is estimated as
half of the total settlement conditions or 1½ inches. As such, considering differential settlement
for the combined settlement conditions (Static and Seismic) applied over a typical foundation
distance of 40 feet, the actual angular distortion (1:280) does not meet the allowable 1:480
(Riverside County, 2003). Per SP117A, these settlements fall under the category of structural
mitigation. Considering liquefaction, structural mitigation measures should be applied to achieve
a foundation that can withstand a distortion of 1:280. Considering subsidence, we recommend a
more stringent settlement case of 1:240 be used for design (2 inches in 40 feet).
Earthquake Performance Statement: Depending upon the extent of structural and geotechnical
design of structures, exterior flatwork, walls, utilities, roadways, and other similar site
improvements, some damage due to seismic events will occur. We recommend a standard
statement for purchasers of the property and within title reports that seismic induced damage
may occur. Note that all of southern California in general is in earthquake country. Site
developments in southern California are typically not designed to mitigate anticipated seismic
events without some damage. In fact, the Building Code is intended to provide Life‐Safety
performance, not complete damage‐free design. In other words, some damage from earthquakes
in the form of structural damage, settlement, cracking, and disruption of utilities is expected and
that repair after an earthquake event will likely be required. It is not the current standard of care
for site developers to fully mitigate all anticipated earthquake induced hazards. It is incumbent
on the developer to advise the end‐users of the project of the anticipated hazards in the form of
disclosure statements during the initial and subsequent purchase processes.
According to literature form Robert W. Day, doors and windows may stick at distortion angles
between 1:240 and 1:175. In this situation, a human being could be put in a life‐threatening
situation. Therefore, Earth Systems recommends the maximum distortion angle using all the
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settlement conditions including seismic settlements be 1:240. For all settlement conditions
excluding seismic settlement, the structure’s maximum distortion angle should be the California
Building Code’s 1:360.
Seismic Design Criteria
This site is subject to strong ground shaking due to potential fault movements along regional
faults including the San Andreas and San Jacinto fault zones. Engineered design and earthquake‐
resistant construction increase safety and allow development of seismic areas. The minimum
seismic design should comply with the 2019 edition of the California Building Code and ASCE 7‐
16 using the seismic coefficients given in the table below. General Procedure seismic parameters
are presented below per ASCE7‐16 exception, considering a Site Class D (based on Vs shear wave
velocity) for structures not greater than 0.5 seconds in period. Structures greater than 0.5
seconds in period will require a Site‐Specific Seismic evaluation and the values presented below
are not valid (ASCE7‐16, Section 20.3.1). For foundations described within, site soils are not
subject to bearing failure.
General Procedure for seismic parameters is presented below considering a Site Class D shear
wave velocity (results in Appendix A). Values were obtained from a web site (OSHPD Seismic
Design Maps) using a coordinate location of Latitude 33.6280°N and Longitude 116.2543°W. The
structural design engineer should use the most conservative results based of the specific building
design and spectral response. Further design values are attached with this report.
Table 3
2019 CBC (ASCE 7‐16) Seismic Parameters
Site Class:
Risk Category:
D
II
Seismic Design Category D
Maximum Considered Earthquake [MCE] Ground Motion
Short Period Spectral Response Ss: 1.500 g
1 second Spectral Response, S1: 0.600 g
Code Design Earthquake Ground Motion
Fa
Fv
FPGA
SMS
SM1
1.0
1.7
1.1
1.500g
1.020g
Short Period Spectral Response, SDS 1.000g
1 second Spectral Response, SD1 0.680g
Peak Ground Acceleration (PGAM) Eq 11.8‐1 0.63g
The intent of the CBC lateral force requirements is to provide a structural design that will resist
collapse to provide reasonable life safety from a major earthquake but may experience some
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structural and nonstructural damage. A fundamental tenet of seismic design is that inelastic
yielding is allowed to adapt to the seismic demand on the structure. In other words, damage is
allowed. The CBC lateral force requirements should be considered a minimum design. The owner
and the designer may evaluate the level of risk and performance that is acceptable. Performance
based criteria could be set in the design. The design engineer should exercise special care so that
all components of the design are fully met with attention to providing a continuous load path.
An adequate quality assurance and control program is urged during project construction to verify
that the design plans and good construction practices are followed. This is especially important
for sites lying close to the major seismic sources.
Estimated peak horizontal site accelerations are based upon a probabilistic analysis (2 percent
probability of occurrence in 50 years) is approximately 0.75 g for a stiff soil site
(https://www.conservation.ca.gov/cgs/...). Actual accelerations may be more or less than
estimated. Vertical accelerations are typically ⅓ to ⅔ of the horizontal acceleraƟons, but can
equal or exceed the horizontal accelerations, depending upon the local site effects and
amplification.
Retaining Walls
Retaining walls should not be backfilled with compacted soils unless verified to be “very
low” in expansion potential. If testing is not performed by the contractor, we recommend
that proposed retaining walls and below grade walls be backfilled with non‐or expansive,
or “very low” expansive import soil. Provided the wall is backfilled at a 1:1 projection
upward from the heels of the wall footings with non‐expansive granular backfill, an active
pressure of 40 pcf of equivalent fluid weight for well‐drained, level backfill may be used.
Similarly, an active pressure of 50 pcf of equivalent fluid weight may be used for well‐
drained backfill sloping at 2H:1V (horizontal to vertical). For the restrained level backfill
condition, a pressure of 61 pcf of equivalent fluid weight should be used.
In addition to the active or at rest soil pressure, the proposed wall structures should be
designed to include forces from dynamic (seismic) earth pressure (Atik and Sitar, 2010).
Dynamic pressures are additive to active and at‐rest earth pressure and should be
considered as 24 pcf for flexible walls, and 38 pcf for rigid walls. Seismic pressures are
based on PGAM of 0.63g, Friction Soil Angle (of 31o, and a maximum dry density of 125
pcf. A factor of safety of 1.5 should be used in stability analysis except for dynamic earth
pressure where a factor of safety of 1.2 is acceptable.
Retaining wall foundations should be placed upon compacted fill described in the
referenced (Earth Systems, 2005) project soils report.
A backdrain or an equivalent system of backfill drainage should be incorporated into the
wall design, whereby the collected water is conveyed to an approved point of discharge.
Design should be in accordance with the 2019 California Building Code. Drain rock should
be wrapped in filter fabric such as Mirafi 140N as a minimum and have at least 1 cubic
foot of rock per foot of length. Backfill immediately behind the retaining structure should
be a free‐draining granular. Waterproofing should be according to the designer’s
specifications. Water should not be allowed to pond or infiltrate near the top of the wall.
To accomplish this, the final backfill grade should divert water away from retaining walls.
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Compaction on the retained side of the wall within a horizontal distance equal to one wall
height (to a maximum of 6 feet) should be performed by hand‐operated or other
lightweight compaction equipment (90% compaction relative to ASTM D 1557 at near
optimum moisture content). This is intended to reduce potential locked‐in lateral
pressures caused by compaction with heavy grading equipment or dislodging modular
block type walls.
The above recommended values do not include compaction or truck‐induced wall
pressures. Care must be taken during the compaction operation not to overstress the
wall. Heavy construction equipment should be maintained a distance of at least 3 feet
away from the walls while the backfill soils are placed. Upward sloping backfill or
surcharge loads from nearby footings can create larger lateral pressures. Should any walls
be considered for retaining sloped backfill or placed next to foundations, our office should
be contacted for recommended design parameters. Surcharge loads should be
considered if they exist within a zone between the face of the wall and a plane projected
45 degrees upward from the base of the wall. The increase in lateral earth pressure
should be taken as 50% of the surcharge load within this zone. Retaining walls subjected
to traffic loads should include a uniform surcharge load equivalent of 240 psf for auto and
450 psf for truck traffic located at least 3 feet from the wall back edge. Closer loads will
impart greater pressures on the wall. Retaining walls should be designed with a minimum
factor of safety of 1.5.
Frictional and Lateral Coefficients:
Resistance to lateral loads (including those due to wind or seismic forces) may be provided
by frictional resistance between the bottom of concrete foundations and the underlying
soil, and by passive soil pressure against the foundations. An allowable coefficient of
friction of 0.35 may be used between cast‐in‐place concrete foundations and slabs and
the underlying soil. An allowable coefficient of friction of 0.30 may be used between pre‐
cast or formed concrete foundations and slabs and the underlying soil
Allowable passive pressure (for granular backfill referenced above) may be taken as
equivalent to the pressure exerted by a fluid weighing 250 pounds per cubic foot (pcf).
Vertical uplift resistance may consider a soil unit weight of 105 pounds per cubic foot.
The upper 1 foot of soil should not be considered when calculating passive pressure
unless confined by overlying asphalt concrete pavement or Portland cement concrete
slab. The soils pressures presented have considered onsite fill soils. Testing or
observation should be performed during grading by the soils engineer or his
representative to confirm or revise the presented values.
Passive resistance for thrust blocks bearing against firm natural soil or properly
compacted backfill can be calculated using an equivalent fluid pressure of 250 pcf. The
maximum passive resistance should not exceed 1,500 psf.
Construction employing poles or posts (i.e. lamp posts) may utilize design methods and
parameters presented in Section 1807.3 of the CBC for sand (ML) material class. If design
uses toe bearing stress, the contractor shall allow safe access for testing of the bottom of
the excavation.
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The passive resistance of the subsurface soils will diminish or be non‐existent if trench
sidewalls slough, cave, or are over widened during or following excavations. If this
condition is encountered, our firm should be notified to review the condition and provide
remedial recommendations, if warranted.
Grading Observation and Testing
Proper geotechnical observation and testing during construction is imperative to allow the
geotechnical engineer the opportunity to verify assumptions made during the design process, to
verify that our geotechnical recommendations have been properly interpreted and implemented
during construction and is required by the 2019 California Building Code. Observation of fill
placement and soils inspection by the Geotechnical Engineer of Record should be in conformance
with Section 17 of the 2019 California Building Code as applicable. California Building Code
requires observation by the geotechnical consultant or his representative during site grading (fill
placement). It is also recommended that footing subgrade, backfill, utility trench backfill, etc. be
verified for minimum soil compaction level. Therefore, we recommend that Earth Systems be
retained during the construction of the proposed improvements to provide testing and observe
compliance with the design concepts and geotechnical recommendations, and to allow design
changes in the event that subsurface conditions or methods of construction differ from those
assumed while completing our previous study where shoring or underpinning are required,
recommendations should be provided on a case‐by‐case basis by the geotechnical consultant.
Limitations
Except as modified in this report, it is our opinion that the referenced documents, including
limitations, are applicable to the proposed development in regard to geotechnical and geologic
constraints. This report and our scope of services are not intended to address any environmental
issues or constraints related to the site or our observations. Earth Systems has striven to provide
our services in accordance with generally accepted geotechnical engineering practices in this locality
at this time. Observations reported are those existing at the time of our services and may not be
the same or comparable at other times. Our scope of work was to present our client with a source
of professional opinion. Our observation and opinions presented are not insurance, nor do they
guarantee construction of any type. This assessment does not include, and specifically excludes,
observation of inaccessible areas. Only those conditions apparent upon reasonable visual
observation are noted. If additional information becomes available, we must be consulted to review
the effect of the information on our conclusions. No warranty or guarantee, express or implied, is
made.
Our findings and recommendations in this report are based on our points of current and previous
field exploration, laboratory testing, and our understanding of the proposed
project. Furthermore, our findings and recommendations are based on the assumption that soil
conditions do not vary significantly from those found at specific exploratory locations. Variations
in soil or groundwater conditions could exist between and beyond the exploration points. The
nature and extent of these variations may not become evident until construction. Variations in
soil or groundwater may require additional studies, consultation, and possible revisions to our
recommendations. It is recommended that Earth Systems be retai ned during the construction of
the proposed improvements to observe compliance with the design concepts and geotechnical
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recommendations, and to allow design changes in the event that subsurface conditions or
methods of construction differ from those assumed while completing this commission. If we are
not accorded the privilege of performing this review, we can assume no responsibility for
misinterpretation of our recommendations. The above services can be provided in accordance
with our current Fee Schedule. The geotechnical engineering firm providing tests and
observations shall assume the responsibility of Geotechnical Engineer of Record.
Our evaluation of subsurface conditions at the site has considered subgrade soil and groundwater
conditions present at the time of our study. The influence(s) of post‐construction changes to
these conditions such as introduction or removal of water into or from the subsurface will likely
influence future performance of the proposed project. It should be recognized that definition
and evaluation of subsurface conditions are difficult. Judgments leading to conclusions and
recommendations are generally made with incomplete knowledge of the subsurface conditions
due to the limitation of data from field studies. The availability and broadening of knowledge
and professional standards applicable to engineering services are continually evolving. As such,
our services are intended to provide the Client with a source of professional advice, opinions and
recommendations based on the information available as applicable to the project location, time
of our services, and scope. If the scope of the proposed construction changes from that
described in our reports, the conclusions and recommendations contained in this report are not
considered valid unless the changes are reviewed, and the conclusions and recommendations of
our reports are modified or approved in writing by Earth Systems.
Findings of this report are valid as of the issued date of the report and are strictly for the
client. Changes in conditions of a property can occur with passage of time, whether they are
from natural processes or works of man, on this or adjoining properties. In addition, changes in
applicable standards occur, whether they result from legislation or broadening of
knowledge. Accordingly, findings of this report may be invalidated wholly or partially by changes
outside our control. Therefore, this report is subject to review and should not be relied upon
after a period of one year.
This report is issued with the understanding that the owner or the owner’s representative has
the responsibility to bring the information and recommendations contained herein to the
attention of the architect and engineers for the project so that they are incorporated into the
plans and specifications for the project. The owner or the owner’s representative also has the
responsibility to take the necessary steps to see that the general contractor and all
subcontractors follow such recommendations. It is further understood that the owner or the
owner’s representative is responsible for submittal of this report to the appropriate governing
agencies.
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References
Bartlett, F. Steven., and Youd T. Leslie., 2002, Empirical Prediction of Liquefaction‐Induced Lateral
Spread, J. Geotechnical and Geoenvironmental Eng., ASCE 121 (4), 316‐329.
Coachella Valley Water District, 2012, Coachella Valley Water Management Plan 2010 Update
(Final Report), Prepared by MWH, dated January 2012, 286 pages.
Coachella Valley Water District, 1965, Coachella Valley Drainage and Stormwater Outlet
System, Drawing No.: 46‐8, 1 sheet.
Earth Systems, 2005, Geotechnical Engineering Report, Proposed 20‐Acre Residential
Development, 80‐700 Avenue 58, West of Madison Street, La Quinta, California, File No. 10109‐
01, Doc No.: 05‐05‐771, dated May 18, 2005.
Earth Systems, 2006, Update to Geotechnical Engineering Report, Proposed Residential
Development, 80‐700 Avenue 58, La Quinta, California, File No.: 10109‐04, Doc. No.: 06‐11‐700,
dated November 1, 2006.
Earth Systems, 2007, Report of Testing and Observation Performed during Grading, Tract 34243;
Pasatiempo, Avenue 58 West of Madison, La Quinta, California, File No.: 10109‐05, Doc. No.: 07‐
04‐857, dated May 1, 2007.
Earth Systems, 2007, Proposed Interlocking Concrete Pavers, Tract 34243; Pasatiempo, Avenue
58 West of Madison, La Quinta, California, File No.: 10109‐05, Doc. No.: 07‐08‐790, dated August
9, 2007.
Earth Systems, 2011, Geotechnical Engineering Report Update with Supplemental
Recommendations, Tract 34243; Pasatiempo, Avenue 58 West of Madison, La Quinta, California,
File No.: 10109‐06, Doc. No.: 11‐05‐752, dated May 31, 2011.
Earth Systems, 2012, Foundation Plan Review, Tract 34243; Coral Mountain Residential
Developments (formerly known as Pasatiempo), Avenue 58 West of Madison, La Quinta,
California, File No.: 10109‐06, Doc. No.: 12‐12‐705, dated December 6, 2012.
Earth Systems, 2013, Report of Testing and Observations for Pad Certifications, Lots 43, 57, 59 &
61, Tract 34243; Coral Mountain Residential Developments, La Quinta, California, File No.: 10109‐
07, Doc. No.: 13‐02‐708, dated February 7, 2013.
Earth Systems, 2013, Report of Testing and Observations for Pad Certifications, Lots 48 Through
55, Tract 34243; Coral Mountain Residential Developments, La Quinta, California, File No.: 10109‐
07, Doc. No.: 13‐08‐721, dated August 14, 2013.
Earth Systems, 2013, Post Tension Reports; Multiple Reports; Coral Mountain Residential
Developments, La Quinta, California, File No.: 10109‐09, Doc. No.: Multiple Documents.
Earth Systems, 2014, Report of Testing and Observations for Pad Certifications, Lots 17 Through
28, Tract 34243; Coral Mountain Residential Developments, La Quinta, California, File No.: 10109‐
07, Doc. No.: 14‐03‐704, dated March 5, 2014.
Riverside County Planning Department, 2003, Geotechnical Element of the Riverside County
General Plan.
Approximate Scale: 1" = 1 Mile
0 1 Mile 2 Miles
LEGEND
Approximate Site Boundary
Plate I
Site Vicinity Map
Coral Mountain (Previously Pasatiempo)
Avenue 58, West of Madison
Palm Desert, Riverside County, California
Earth Systems
12/16/2020 File No.: 300310-002
Source: Google Earth satellite image with USGS topographic map overlay.
Approximate Site Approximate Site
LocationLocation
(33.6281°, 116.2550°)(33.6281°, 116.2550°)
Approximate Site
Location
(33.6281°, 116.2550°)
Ma
d
i
s
o
n
S
t
Ma
d
i
s
o
n
S
t
Ma
d
i
s
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S
t
Avenue 58Avenue 58Avenue 58
Je
f
f
e
r
s
o
n
S
t
Je
f
f
e
r
s
o
n
S
t
Je
f
f
e
r
s
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S
t
Approximate Scale: 1" = 175’
0 175’ 350’
LEGEND
Approximate Exploration Locations
Plate 2
Current Exploration Location Map
Coral Mountain (Previously Pasatiempo)
Avenue 58, West of Madison
Palm Desert, Riverside County, California
Earth S y s t e m s
12/16/2020 File No.: 300310-002
Source: Google Earth satellite image dated 12/11/2019.
Avenue 58Avenue 58Avenue 58
B-2B-2B-2
(50’)(50’)(50’)(Depth in Feet)
B-2B-2B-2
(50’)(50’)(50’)
B-1B-1B-1
(50’)(50’)(50’)
Photo 1 June 2009 Aerial Photo
Photo 2 November 2011 Aerial Photo
Photo 3 April 2014 Aerial Photo
Photo 4 March 2015 Aerial Photo
Photo 5 December 2019
Coral Mountain (aka Pasatiempo)301432‐002
Upper Lower Avg Avg Avg Trace Mean
Seis. Seis. Dip Dip Rake Length Fault Mean Return Slip
Fault Section Name Depth Depth Angle Direction Type Mag Interval Rate
(miles) (km) (km) (km) (deg.) (deg.) (deg.) (km) (years) (mm/yr)
San Andreas (Mojave S) 7.2 11.6 0.0 13.1 90 206 180 98 A 7.7 102 29
San Andreas (Coachella) rev 8.3 13.4 0.0 11.1 90 224 180 69 A 7.2 69 20
San Andreas (San Gorgonio Pass‐Garnet HIll) 11.1 17.8 0.0 12.8 58 20 180 56 A 7.6 219 10
San Andreas, (North Branch, Mill Creek) 11.1 17.8 0.0 18.2 76 204 180 106 A 7.5 110 17
San Jacinto (Clark) rev 16.6 26.8 0.0 16.8 90 214 180 47 A 7.6 211 14
San Jacinto (Anza) rev 17.7 28.5 0.0 16.8 90 216 180 46 A 7.6 151 18
San Jacinto (Coyote Creek) 19.0 30.5 0.0 15.9 90 223 180 43 A 7.3 259 4
Blue Cut 19.1 30.8 0.0 13.1 90 177 na 79 B'7.1
Joshua Tree (Seismicity) 21.2 34.1 0.0 13.3 90 271 na 17 B'6.5
Burnt Mtn 22.6 36.3 0.0 15.9 67 265 180 21 B 6.7 0.6
Eureka Peak 23.5 37.9 0.0 15.0 90 75 180 19 B 6.6 0.6
San Jacinto (Borrego) 29.2 47.0 0.0 13.1 90 223 180 34 A 7.0 146 4
Brawley (Seismic Zone), alt 1 31.6 50.8 0.0 13.2 90 250 na 60 B'7.0
Mission Creek 31.7 51.0 0.0 17.7 65 5 180 31 B'6.9
Pinto Mtn 35.6 57.3 0.0 15.5 90 175 0 74 B 7.2 2.5
Earthquake Valley (No Extension) 35.7 57.5 0.0 18.8 90 221 180 33 B'6.9
Earthquake Valley 36.3 58.5 0.0 18.8 90 217 180 20 B 6.7 2
So Emerson‐Copper Mtn 36.8 59.3 0.0 14.1 90 51 180 54 B 7.0 0.6
San Gorgonio Pass 37.0 59.6 0.0 18.5 60 11 na 29 B'6.9
Brawley (Seismic Zone), alt 2 37.1 59.8 0.0 13.2 90 250 na 61 B'7.0
Pisgah‐Bullion Mtn‐Mesquite Lk 38.0 61.1 0.0 13.1 90 60 180 88 B 7.3 0.8
Calico‐Hidalgo 38.0 61.2 0.0 13.9 90 52 180 117 B 7.4 1.8
San Jacinto (San Jacinto Valley, stepover) 38.3 61.6 0.0 16.1 90 224 180 24 A 7.4 199 9
Landers 38.5 62.0 0.0 15.1 90 60 180 95 B 7.4 0.6
San Jacinto (Anza, stepover) 38.7 62.2 0.0 16.8 90 224 180 25 A 7.6 151 9
San Jacinto (Stepovers Combined) 38.7 62.2 0.0 16.5 90 229 180 25 B'6.7
Earthquake Valley (So Extension) 39.5 63.5 0.0 18.8 90 204 180 9 B'6.3
San Andreas (San Bernardino S) 39.7 63.9 0.0 12.8 90 210 180 43 A 7.6 150 16
Elsinore (Julian) 39.8 64.1 0.0 18.8 84 36 180 75 A 7.6 725 3
Elmore Ranch 44.8 72.1 0.0 11.4 90 310 0 29 B 6.6 1
Elsinore (Coyote Mountain) 45.4 73.0 0.0 13.2 82 35 180 39 A 7.1 322 3
Superstition Hills 45.9 73.9 0.0 12.6 90 220 180 36 A 7.4 199 4
San Jacinto (Superstition Mtn) 46.9 75.4 0.0 12.4 90 210 180 26 B'6.6
Elsinore (Temecula) rev 47.3 76.1 0.0 14.2 90 230 180 40 A 7.4 431 5
Superstition Mountain 47.9 77.0 37.1 37.1 37 37 37 37 B 7.0 0.1
Johnson Valley (No) 48.7 78.4 0.0 15.9 90 51 180 35 B 6.8 0.6
North Frontal (East) 49.6 79.8 0.0 16.6 41 187 90 27 B 6.9 0.5
San Jacinto (San Jacinto Valley) rev 51.6 83.1 0.0 16.1 90 223 180 18 A 7.4 199 18
Lenwood‐Lockhart‐Old Woman Springs 54.6 87.8 0.0 13.2 90 43 180 145 B 7.5 0.9
Helendale‐So Lockhart 57.8 93.1 0.0 12.8 90 51 180 114 B 7.4 0.6
Reference: USGS OFR 2007‐1437 (CGS SP 203) Based on Site Coordinates of 33.628 Latitude, ‐116.2543 Longitude
Distance
Table 1
Fault Parameters
Mean Magnitude for Type A Faults based on 0.1 weight for unsegmented section, 0.9 weight for segmented model (weighted by probability of each scenario with
section listed as given on Table 3 of Appendix G in OFR 2007‐1437). Mean magntude is average of Ellworths‐B and Hanks & Bakun moment area relationship.
Coral Mountain (aka Pasatiempo) 301432‐002
Site Coordinates: 33.628 N 116.254 W
Table 2
Historic Earthquakes in Vicinity of Project Site, M >= 5.5
Epicenter Distance
Latittude Longitude from Magnitude
Day Year (Degrees) Site (mi)
MW
3/25 1937 33.46 116.44 15.8 5.6
2/9 *1890 33.40 116.30 16.0 6.8
4/11 1910 33.50 116.50 16.7 5.8
4/23 1992 33.96 116.32 23.2 6.2
3/19 1954 33.29 116.07 25.6 6.4
6/6 1918 33.60 116.70 25.7 5.5
10/2 1928 33.60 116.70 25.7 5.5
12/4 1948 34.00 116.23 25.7 6.0
4/3 1926 34.00 116.00 29.5 5.5
5/28 *1892 33.20 116.20 29.7 6.5
9/30 1916 33.20 116.10 30.9 5.7
7/8 1986 34.00 116.61 32.8 6.0
4/9 1968 33.17 116.09 33.0 6.6
6/29 1992 34.10 116.40 33.6 5.7
6/28 1992 34.12 116.32 34.2 5.7
6/28 1992 34.13 116.41 35.8 5.8
6/28 1992 34.20 116.44 40.9 7.3
2/7 1889 34.10 116.70 41.4 5.6
5/2 1949 33.99 115.67 41.8 5.7
4/21 *1918 33.75 117.00 43.7 6.8
12/25 *1899 33.80 117.00 44.4 6.7
9/21 1856 33.10 116.70 44.6 5.5
11/24 1987 33.09 115.79 45.8 6.0
11/24 1987 33.02 115.85 48.0 6.5
8/15 1945 33.16 115.61 49.2 5.8
3/15 1979 34.33 116.44 49.6 5.5
10/22 1942 33.28 115.50 49.7 5.7
11/22 1880 34.00 117.00 49.9 5.5
12/19 1880 34.00 117.00 49.9 5.9
6/28 1992 34.16 116.85 50.1 5.5
6/28 1992 34.20 116.83 51.5 6.5
4/26 1981 33.10 115.62 51.6 5.9
1/16 1930 34.20 116.90 54.1 5.5
10/21 1942 32.97 115.74 54.3 6.4
8/26 2012 33.02 115.55 13.0 5.5
10/16 1979 33.01 115.56 58.5 5.6
10/16 1999 34.24 117.04 61.7 5.6
9/20 *1907 34.20 117.10 62.5 5.8
7/23 *1923 34.00 117.25 62.6 6.2
10/23 1894 32.80 116.80 65.3 6.1
From full earthquake catalog in USGS OFR 2007‐1437h as updated with current
events through 2019. For events with an asterisk, alternate solutions are given in
Terms and Symbols Used on Boring Logs
Earth Systems
DESCRIPTION FIELD TEST
A 1/8 in. (3-mm) thread cannot be rolled
at any moisture content.
Nonplastic
PLASTICITY
Low
Medium
High
The thread can barely be rolled.
The thread is easy to roll and not much
time is required to reach the plastic limit.
The thread can be rerolled several timesafter reaching the plastic limit.
MOISTURE CONDITION
Dry.....................Absence of moisture, dusty, dry to the touch
Damp................Slight indication of moisture
Moist.................Color change with short period of air exposure (granular soil)
Below optimum moisture content (cohesive soil)
Wet....................High degree of saturation by visual and touch (granular soil)
Above optimum moisture content (cohesive soil)
Saturated..........Free surface water
RELATIVE PROPORTIONS
Trace.............minor amount (<5%)
with/some......significant amount
modifier/and...sufficient amount to
influence material behavior
(Typically >30%)
Moisture Condition:
Moisture Content:
Dry Density:
An observational term; dry, damp, moist, wet, saturated.
The weight of water in a sample divided by the weight of dry soil in the soil sample
expressed as a percentage.
The pounds of dry soil in a cubic foot.
MOISTURE DENSITY
Very Soft
Soft
Medium Stiff
Stiff
Very Stiff
Hard
*N=0-1
N=2-4
N=5-8
N=9-15
N=16-30
N>30
*C=0-250 psf
C=250-500 psf
C=500-1000 psf
C=1000-2000 psf
C=2000-4000 psf
C>4000
Squeezes between fingers
Easily molded by finger pressure
Molded by strong finger pressure
Dented by strong finger pressure
Dented slightly by finger pressure
Dented slightly by a pencil point or thumbnail
CONSISTENCY OF COHESIVE SOILS (CLAY OR CLAYEY SOILS)
Very Loose
Loose
Medium Dense
Dense
Very Dense
*N=0-4
N=5-10
N=11-30
N=31-50
N>50
RD=0-30
RD=30-50
RD=50-70
RD=70-90
RD=90-100
Easily push a 1/2-inch reinforcing rod by hand
Push a 1/2-inch reinforcing rod by hand
Easily drive a 1/2-inch reinforcing rod with hammer
Drive a 1/2-inch reinforcing rod 1 foot with difficulty by a hammer
Drive a 1/2-inch reinforcing rod a few inches with hammer
*N=Blows per foot in the Standard Penetration Test at 60% theoretical energy. For the 3-inch diameter Modified California
sampler,140-pound weight, multiply the blow count by 0.63 (about 2/3) to estimate N. If automatic hammer is used, multiply
a factor of 1.3 to 1.5 to estimate N. RD=Relative Density (%). C=Undrained shear strength (cohesion).
RELATIVE DENSITY OF GRANULAR SOILS (GRAVELS, SANDS, AND NON-PLASTIC SILTS)
SOIL GRAIN SIZE
12”3”3/4”4 10 40 200
305 76.2 19.1 4.76 2.00 0.42 0.074 0.002
SOIL GRAIN SIZE IN MILLIMETERS
U.S. STANDARD SIEVE
COARSE FINEBOULDERSCOBBLESGRAVEL SAND
COARSE MEDIUM FINE SILT CLAY
Soil classification is based on ASTM Designations D 2487 and D 2488 (Unified Soil Classification System). Information on each boring
log is a compilation of subsurface conditions obtained from the field as well as from laboratory testing of selected samples. The
indicated boundaries between strata on the boring logs are approximate only and may be transitional.
DESCRIPTIVE SOIL CLASSIFICATION
LOG KEY SYMBOLS
Bulk, Bag or Grab Sample
Standard Penetration
Split Spoon Sampler
(2” outside diameter)
Modified California Sampler
(3” outside diameter)
No Recovery
GROUNDWATER LEVEL
Water Level (measured or after drilling)
Water Level (during drilling)
Soil Classification System
Earth Systems
MAJOR DIVISIONS GRAPHIC
SYMBOL
LETTER
SYMBOL TYPICAL DESCRIPTIONS
COARSE
GRAINED SOILS
FINE-GRAINED
SOILS
GRAVEL AND
GRAVELLY
SOILS
SAND AND
SANDY SOILS
SILTS AND
CLAYS
CLEAN
GRAVELS
GRAVELS
WITH FINES
CLEAN SAND
(Little or no fines)
SAND WITH FINES
(appreciable
amount of fines)
LIQUID LIMIT
THAN 50LESS
LIQUID LIMIT
GREATER
THAN 50
HIGHLY ORGANIC SOILS
VARIOUS SOILS AND MAN MADE MATERIALS
MAN MADE MATERIALS
PT
GW
GP
GM
GC
SW
SP
SM
SC
ML
CL
OL
MH
CH
OH
Well-graded gravels, gravel-sand
mixtures, little or no fines
Poorly-graded gravels, gravel-sand
mixtures. Little or no fines
Silty gravels, gravel-sand-silt
mixtures
Clayey gravels, gravel-sand-clay
mixtures
More than 50% of
material is larger
than No. 200
sieve size
More than 50% of
material is smaller
than No. 200
sieve size
More than 50% of
coarse fraction
No. 4 sievepassing
Well-graded sands, gravelly sands,
little or no fines
Poorly-graded sands, gravelly
sands, little or no fines
Silty sands, sand-silt mixtures
Clayey sands, sand-clay mixtures
Inorganic silts and very fine sands,
rock flour, silty low clayey fine sands
or clayey silts with slight plasticity
Inorganic clays of low to medium
plasticity, gravelly clays, sandy
clays, silty clays, lean clays
Organic silts and organic silty
clays of low plasticity
Inorganic silty, micaceous, or
diatomaceous fine sand or
silty soils
Inorganic clays of high plasticity,
fat clays
Organic clays of medium to high
plasticity, organic silts
Peat, humus, swamp soils with
high organic contents
Fill Materials
Asphalt and concrete
More than 50% of
coarse fraction
on No. 4retained
sieve
Page 1 of 1
0
5
10
15
20
25
30
35
40
45
50
55
60
Boring No.
Project Name:
Project Number
Boring Location:
Drilling Method:
De
p
t
h
(
F
t
.
)
Sample
Type Penetration
Resistance
(Blows/6")Sy
m
b
o
l
US
C
S
Dr
y
D
e
n
s
i
t
y
Drilling Date:
Drill Type:
Logged By:
Bu
l
k
SP
T
MO
D
C
a
l
i
f
.
Description of Units
(p
c
f
)
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
Note: The stratification lines shown represent the
approximate boundary between soil and/or rock types
and the transition may be gradational.Blow Count Dry Density
Graphic Trend
Earth Systems
Total Depth 51-1/2 feet
Backfilled with cuttings
No groundwater encountered, No free water observed
medium dense
medium dense
SILTY SAND: olive gray, dense, dry, fine grained sand
POORLY GRADED SAND WITH SILT: olive gray,
damp, dense, fine grained sand
SILTY SAND: olive gray, dry, fine grained sand
SANDY SILT: olive gray, damp, very stiff, fine grained
sand
SILTY SAND: olive gray, dry, medium dense, fine
grained sand
SANDY LEAN CLAY: olive brown, very stiff, damp,
fine grained sand
SILTY SAND: olive gray, medium dense, dry, fine
grained sand
SANDY LEAN CLAY: dark olilve brown, stiff, very
moist, fine grained sand
POORLY GRADED SAND WITH SILT: olive gray,
dense, dry, fine grained sand
SANDY LEAN CLAY: dark brown, stiff, wet, fine
grained sand
3
2
2
4
2
34
2
2
38
112
104
100
89
106
87
110
111
86
SM
SP-SM
SM
ML
SM
CL
SM
CL
SP-SM
CL
16,21,33
12,20,38
8,12,13
5,10,10
5,7,10
6,15,23
4,8,14
6,13,22
4,6,10
9,16,24
12,16,22
4,8,7
B-1
Coral Mountain
300310-002
See Plate 2
12/2/202
B-61 w/autohammer
8" HSA
A. Lee
1680 Illinois Ave., Suite 20, Perris, CA 92571
Phone (951) 928-9799
Page 1 of 1
0
5
10
15
20
25
30
35
40
45
50
55
60
Boring No.
Project Name:
Project Number
Boring Location:
Drilling Method:
De
p
t
h
(
F
t
.
)
Sample
Type Penetration
Resistance
(Blows/6")Sy
m
b
o
l
US
C
S
Dr
y
D
e
n
s
i
t
y
Drilling Date:
Drill Type:
Logged By:
Bu
l
k
SP
T
MO
D
C
a
l
i
f
.
Description of Units
(p
c
f
)
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
Note: The stratification lines shown represent the
approximate boundary between soil and/or rock types
and the transition may be gradational.Blow Count Dry Density
Graphic Trend
Earth Systems
Total Depth 51-1/2 feet
Backfilled with cuttings
Groundwater encountered at 49 feet
free water
stiff
medium dense, damp
SILTY SAND: olive gray, dense, dry, fine grained sand
SANDY LEAN CLAY: olive gray brown, stiff, moist,
fine grained sand
SILTY SAND: olive brown, medium dense, damp, fine
grained sand
POORLY GRADED SAND WITH SILT: olive brown,
medium dense, damp, fine grained sand, trace clay
SILTY SAND: olive brown, dense, damp, fine grained
sand
SANDY LEAN CLAY: dark brown, very stiff, fine
grained sand and silt
3
12
8
5
37
39
103
SM
CL
SM
SP-SM
SM
CL
18,24,33
11,11,16
7,8,13
3,3,4
6,7,10
3,5,7
4,7,11
6,9,12
6,7,9
2,3,3
B-2
Coral Mountain
300310-002
See Plate 2
12/2/202
B-61 w/autohammer
8" HSA
A. Lee
1680 Illinois Ave., Suite 20, Perris, CA 92571
Phone (951) 928-9799
Boring No.Project and Number 12345 678910111213 14 15
ESSW Field Staff
Bottom
of Layer
Depth (ft)Blow Type of di N60 N70 N60HE Vsi**Vsi Фi di/N60HEi di/Vsi di/Фi
Consistency if
Coarse Grained
(Based on
ASTM and
Corrected for
N60)
Consistency if
Fine Grained
(Based on
ASTM and
Corrected for
N60)
Drilling Company Count*** Sampler (feet) (blows/ft) (blows/ft) (blows/ft) (m/sec) (ft/sec) (degrees)
Drilling Method 6‐8" H S A HSA Inner Diameter 3" 2.5 57 c 2.5 32.32 27.70 43.09 299.32 981.78 36.37 0.05802 0.00255 0.068742 Dense Hard
5.0 57 c 2.5 32.32 27.70 43.09 299.32 981.78 36.37 0.05802 0.00255 0.068742 Dense Hard
7.5 27 c 2.5 15.31 13.12 20.41 241.01 790.51 32.36 0.12248 0.00316 0.077265 Medium Dense Very Stiff
10.0 27 c 2.5 15.31 13.12 20.41 241.01 790.51 32.36 0.12248 0.00316 0.077265 Medium Dense Very Stiff
15.0 21 c 5.0 13.49 11.57 15.88 224.07 734.94 31.19 0.31494 0.00680 0.160325Medium Dense Stiff
20.0 7 s 5.0 9.58 8.21 8.40 186.30 611.06 28.57 0.59524 0.00818 0.174998 Loose Stiff
25.0 17 s 5.0 23.26 19.93 20.40 240.97 790.37 32.35 0.24510 0.00633 0.154543 Medium Dense Very Stiff
Date Drilled 30.0 12 s 5.0 17.28 14.81 14.40 217.82 714.44 30.75 0.34722 0.00700 0.162578 Medium Dense Very Stiff
35.0 18 s 5.0 25.92 22.22 21.60 245.00 803.58 32.63 0.23148 0.00622 0.153228 Medium Dense Very Stiff
feet) 40.0 21 s 5.0 30.24 25.92 25.20 256.20 840.32 33.40 0.19841 0.00595 0.149687 Dense Hard
Hammer Weight (lbs)45.0 16 s 5.0 23.04 19.75 19.20 236.77 776.60 32.06 0.26042 0.00644 0.15594 Medium Dense Very Stiff
140 ` 50.0 6 s 5.0 8.64 7.41 7.20 178.15 584.34 28.01 0.69444 0.00856 0.178529 Loose Stiff
feet) ‐50.0 0.00 0.00 0.00 0.00 0.00 #NUM! #DIV/0! #DIV/0! #NUM! Very Loose Very Soft
Hammer Drop (inches)
30
feet)
Hammer Efficiency (EM)
72
feet)
Borehole Correction (Cb)*
1
*inside diameter of Hollow Stem Auger 718
Sampler Correction Mod Cal to SPT
0.63
219
Sampler Liner Correction (Cs)Total: 0.0 "d" Feet Total: #DIV/0! #DIV/0! #NUM!
1.2 Applied if SPT Sampler Used
1.0 Applied if Cal Sampler Used Ave. Field SPT N‐value (blows/ft)**Used When Boring Depths are less than 100 feet to estimate Shear Wave Velocity over 100 feet. Caltrans Geotechnical Services Design Manual, Version 1.0, August 2009
#DIV/0! using N60HE corrected only for Hammer Energy (Empirical Calculation)
Rod Length Above Ground (ft) feet) *** Uncorrected blowcount not to exceed 100 blows as entry per CBC
3 Consistency classification based upon ASCE 1996
Ave. Field SPT N‐value (blows/ft)
Depth to Estimate Vs Over (ft)*16.5
100 feet)Spreadsheet Version 2.6, 2019: Prepared by Kevin L. Paul, PE, GE
*Caltrans Estimation Method
*Nsub Value Desired For Column 6
70
*Only Used for Calculating Nsub
otherwise not used by program 16
(i.e.N50, N70, N80, etc)
Equipment
variable
Typical
Correction
(%/100)
Donut
Hammer 0.50 to 1.00
Safety
Hammer 0.70 to 1.20 Hammer energy as related to the standard 60% delivered energy, i.e. a 72% hammer has and energy ratio of 1.2, i.e. (72/60=1.2)
Automatic-
Trip Donut-
type
Hammer 0.80 to 1.30
(ft/sec Upper 100 feet)
Decimal Degrees
Soil Profile Type (Site Class)**
D
Ave. Shear Wave Velocity (ft/sec)
Based on
#DIV/0!
Ave. Shear Wave Velocity (ft/sec)
Calculation Results
(Based on Upper 0
(Based on Upper 0
Decimal Degrees
(Based on Upper 0
B‐2
Soil Profile Type (Site Class)
#DIV/0!
Based on Depth Less than 100' ft
Site Latitude (North)
Site Longitude (West)
Estimated Shear Wave Velocity **
Ave. Friction Angle (degrees)
(Based on Upper 0
#DIV/0!
Coral Mountain (Pasat 300310‐002
Notes: Soils Remediated t Upper 5 feet
#NUM!
Ave. SPT N60HE-value (blows/ft)
Energy ratio (Skempton, 1986)
D
Soil Profile Type (Site Class)**
(Based on Upper 0
(Based on Upper 100
(m/sec Upper 100 feet)
Based on
Ave. Field Blow Count
(Upper 100 feet)
EARTH SYSTEMS - EVALUATION OF LIQUEFACTION POTENTIAL
Corral Mountain (aka Pasatiempo) Project No: 300310-002 1996/1998 NCEER Method
Ground Compaction Remediated to 5 foot depth
Boring: B-2 2020 Earthquake Magnitude: 8.2 PGA, g: 0.63 Calc GWT (feet): 30
Total Thickness of Liquefiable Layers: 10.0 feet Estimated Total Ground Subsidence: 1.7 inches
0
10
20
30
40
50
0.0 0.2 0.4 0.6 0.8
De
p
t
h
(
f
e
e
t
)
Cyclic Stress Ratio
EQ CSR CRR
0
10
20
30
40
50
0.0 1.0 2.0
De
p
t
h
(
f
e
e
t
)
Factor of Safety
0
10
20
30
40
50
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
De
p
t
h
(
f
e
e
t
)
Volumetric Strain (%)
0
10
20
30
40
50
0 10203040506070
De
p
t
h
(
f
e
e
t
)
SPT N
SPT N N1(60)
EARTH SYSTEMS - EVALUATION OF DRY SEISMIC SETTLEMENT
Corral Mountain (aka Pasatiempo) Project No: 300310-002 1996/1998 NCEER Method
Ground Compaction Remediated to 5 foot depth
Boring: B-2 2020 Earthquake Magnitude: 8.2 PGA, g: 0.42 Calc GWT (feet): 30
Total Thickness of Liquefiable Layers: 0.0 feet Estimated Total Ground Subsidence: 0.2 inches
0
10
20
30
40
50
0.0 0.2 0.4 0.6 0.8
De
p
t
h
(
f
e
e
t
)
Cyclic Stress Ratio
EQ CSR CRR
0
10
20
30
40
50
0.0 1.0 2.0
De
p
t
h
(
f
e
e
t
)
Factor of Safety
0
10
20
30
40
50
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
De
p
t
h
(
f
e
e
t
)
Volumetric Strain (%)
0
10
20
30
40
50
0 10203040506070
De
p
t
h
(
f
e
e
t
)
SPT N
SPT N N1(60)
File No.: 300310‐002
Lab No.: 20‐214
UNIT DENSITIES AND MOISTURE CONTENT ASTM D2937 & D2216
Job Name: Coral Mt.
Unit Moisture USCS
Sample Depth Dry Content Group
Location (feet) Density (pcf) (%) Symbol
B1 2.5 111.8 2.6 SP‐SM
B1 7.5 103.6 1.6 SM
B1 10 99.6 2.4 SM
B1 15 89.2 3.5 ML
B1 20 105.6 2.2 SM
B1 35 86.7 34.1 CL
B1 40 110.1 2.4 SP‐SM
B1 45 111.4 2.4 SP‐SM
B1 50 86.2 37.9 CL
B2 10 103.3 2.6 SM
B2 30 ‐‐‐ 11.6 SM
B2 35 ‐‐‐ 8.1 SP‐SM
B2 40 ‐‐‐ 5.4 SM
B2 45 ‐‐‐ 36.9 CL
B2 50 ‐‐‐ 38.9 CL
December 14, 2020
EARTH SYSTEMS PACIFIC
File No.: 300310‐002
Job Name: Coral Mt.
Lab Number:20‐214
ASTM D‐1140 or Earth Systems Method (circle one)
AMOUNT PASSING NO. 200 SIEVE (Earth Systems Method Transfers Sample until water runs clear)
Fines USCS
Sample Depth Content Group Soaking
Location (feet) (%) Symbol Time
B1 2.5 8.0 SP‐SM 10
B1 45 10.4 SP‐SM 10
B2 0‐5 16.1 SM 10
B2 35 9.7 SP‐SM 10
December 14, 2020
EARTH SYSTEMS PACIFIC
File No.: 300310‐002
Lab No.: 20‐214
CONSOLIDATION TEST ASTM D 2435 & D 5333
Coral Mt. Initial Dry Density: 93.0 pcf
B1 @ 10 feet Initial Moisture: 6.0%
Specific Gravity: 2.67
Initial Void Ratio: 0.792
Ring Sample
Hydrocollapse: 0.5% @ 2.0 ksf
December 14, 2020
Silty Sand (SM)
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
0.1 1.0 10.0
Pe
r
c
e
n
t
C
h
a
n
g
e
i
n
H
e
i
g
h
t
Vertical Effective Stress, ksf
% Change in Height vs Normal Pressure Diagram
Before Saturation Hydrocollapse
After Saturation Rebound
Poly. (After Saturation)
EARTH SYSTEMS PACIFIC
File No.: 300310‐002
Lab No.: 20‐214
CONSOLIDATION TEST ASTM D 2435 & D 5333
Coral Mt. Initial Dry Density: 82.5 pcf
B1 @ 15 feet Initial Moisture: 6.6%
Specific Gravity: 2.67
Initial Void Ratio: 1.021
Ring Sample
Hydrocollapse: 0.9% @ 2.0 ksf
December 14, 2020
Sandy Silt (ML)
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
0.1 1.0 10.0
Pe
r
c
e
n
t
C
h
a
n
g
e
i
n
H
e
i
g
h
t
Vertical Effective Stress, ksf
% Change in Height vs Normal Pressure Diagram
Before Saturation Hydrocollapse
After Saturation Rebound
Poly. (After Saturation)
EARTH SYSTEMS PACIFIC
File No.: 300310‐002
Lab No.: 20‐214
CONSOLIDATION TEST ASTM D 2435 & D 5333
Coral Mt. Initial Dry Density: 86.0 pcf
B1 @ 35 feet Initial Moisture: 37.3%
Specific Gravity: 2.67
Initial Void Ratio: 0.939
Ring Sample
Hydrocollapse: 0.2% @ 2.0 ksf
December 14, 2020
Clay (CL)
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
0.1 1.0 10.0
Pe
r
c
e
n
t
C
h
a
n
g
e
i
n
H
e
i
g
h
t
Vertical Effective Stress, ksf
% Change in Height vs Normal Pressure Diagram
Before Saturation Hydrocollapse
After Saturation Rebound
Poly. (After Saturation)
EARTH SYSTEMS PACIFIC
File No.: 300310‐002
Lab No.: 20‐214
MAXIMUM DRY DENSITY / OPTIMUM MOISTURE ASTM D 1557 (Modified)
Job Name: Coral Mt. Procedure Used: A
Sample ID: #1 Preparation Method: Moist
Location:B‐1 @ 0‐5 Rammer Type: Mechanical
Description:Lab Number: 20‐214
Sieve Size % Retained (Cumulative)
Maximum Dry Density: 116 pcf 3/4" 0.0
Optimum Moisture: 13.1%3/8" 0.8
Corrected for Oversize (ASTM D4718) #4 2.0
December 14, 2020
Silty Sand (SM)
90
95
100
105
110
115
120
125
130
0 5 10 15 20 25 30 35
Dr
y
D
e
n
s
i
t
y
,
p
c
f
Moisture Content, percent
<-----Zero Air Voids Lines (ZAV),
sg =2.65, 2.70, 2.75
EARTH SYSTEMS PACIFIC