780 N. 4th Street
El Centro, CA 92243
(760) 370-3000
(760) 337-8900 fax
77-948 W ildcat Drive
Palm Desert, CA 92211
(760) 360-0665
(760) 360-0521 fax
LMAND ARK
G eo-Engineers and G eologists
June 15, 2023
Mr. Stefan Vogel
Coachella Valley Community Development Group, Inc.
36101 Bob Hope Drive, Suite E5
Rancho Mirage, CA 92270
Subject: APN 670-110-043
Cathedral City, California
LCI Report No.: LP23130
Reference: Geotechnical Report for Living Care Assisted Living, prepared by LandMark Consultants, Inc., dated October 12, 2016.
Dear Mr. Vogel:
As requested, LandMark Consultants, Inc., is providing an update letter for the referenced geotechnical report located at 30260 Date Palms Drive, Cathedral City, California. The initial field investigation was conducted in September 2016.
Our site visit on June 12 , 2023, found that the site conditions were similar as those encountered during the initial site investigation conducte d in September 2016. Base d on our present field observations and the proposed multi-family residential project, it is our opinion that the findings, recommendations, and conclusions in the referenced geotechnical investigat ion report are still applicable, except for the seismic parameters and site preparation.
Faulting
The project site is located in the seismically active Coachella Valley of southern California with numerous mapped faults of the San Andreas Fault System traversing the region. We have performed a computer-aided search of known faults or seismic zones that lie within a 44-mile (70 kilometer) radius of the project site (Table 1).
Review of the current Alquist-Priolo Earthquake Fault Zone maps (CGS, 2000a) indicates that the nearest mapped Earthquake Fault Zone is the San Andreas – San Bernardino (south) fault located approximately 3.7 mile north-east of the project site.
APN 670-110-043 LCI Report No. LP23130
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General Ground Motion Analysis
The project site is considered likely to be subjected to moderate to strong ground motion from earthquakes in the region. Ground motions are dependent primarily on the earthquake magnitude and distance to the seismogenic (rupture) zone. Acceleration magnitudes also are dependent upon attenuation by rock and soil deposits, direction of rup ture and type of fault; therefore, gr ound motions may vary considerably in the same general area.
2022 CBC General Ground Motion Parameters: The California Building Code (CBC) requires that a site-specific ground motion hazard analysis be performed in accordance with ASCE 7-16 Section
11.4.8 (ASCE, 2016) for structures o n Site Class D with S 1 greater than or equal to 0.2 and Site Class E sites with Ss greater than or equal to 1.0 (CBC, 2022). This project site has been classified as Site Class D and has an S1 value of 0.872, which would require a site-specific ground motion hazard analysis. However, ASCE 7-16 Section 11.4.8 Supplement 3 provides exceptions which permit the use of conservative values of design parameters for certain conditions for Site Cl ass D and E sites in lieu of a site-specific hazard analysis. The exceptions are:
• Site Class D sites: A ground motion hazard analysis is not required where the value of the parameter SM1 determined by Equation 11.4-2 is increased by 50% for all applications of SM1 in ASCE 7-16. The resulting value of the parameter SD1 determined by ASCE 7-16 Equation 11.4-4 shall be used for all applications of SD1 in ASCE 7-16.
• Site Class E sites: A ground motion hazard analysis is not required:
a. Where the equivalent lateral force procedure is used for design and the value of CS is determined by ASCE 7-16 Equation 12.8-2 for all values of T, or b. Where (i) the value of Sai is determined by ASCE 7 -16 Equation 15.7- 10 for all values of Ti and (ii) the value of the paramete r is replaced with 1.5 in ASCE 7-16 Equation 15.7-10 and ASCE 7-16 Equation 15.7-11.
Based on our understanding of the proposed development, the seismic design parameters presented in Table 2 were calculated assuming that one of the exceptions listed above applies to the proposed structures at this site. However, the structural engineer should verify that one of the exceptions is applicable to the proposed structures. If none of the exceptions apply, our office should be consulted to perform a site-specific ground motion hazard analysis.
The 2022 CBC gene ral g round motion parameters are based on the Risk- Targeted Maximum Considered Earthquake (MCE
R). The Structural Engineers Association of California (SEAOC) and APN 670-110-043 LCI Report No. LP23130
LandMark Consultants, Inc. Page 3
Office of Statewide Health Planning an d Development (OSHPD) Seismic Design Maps Web Application (SE AOC, 20 20) was used to obtain the site coefficients a nd adjusted maximum considered earthquake spectral response acceleration parameters. Design spectral response acceleration parameters are defined as the earthquake ground motions that are two-thirds (2/3) of the corresponding MCER ground motions. The Max imum Considered Earthquake Geometric Mean (MCEG) peak ground acceleration adjusted for soil site class effects (PGA M) value to be used for liquefaction and seismic settlement analysis in a ccordance with 2022 CBC Section 1803A.5.12 (PGAM = FPGA*PGA) is estimated at 0.98g for the project site. Design earthquake ground motion parameters are provided in Table 2.
Site Preparation
Clearing and Grubbing: Any surface improvements, debris or vegetation including grass, brush, and weeds, on the site at the time of construction should be removed from the construction area. Root balls should be completely excavated. Organic stripping should be hauled from the site and not used as fill. Any trash, construction debris, concrete slabs, old pavement, landfill, and buried obstructions such as old foundations, swimming pool and utility lines exposed during rough grading should be traced to the limits of the foreign material by the grading contractor and removed under our supervision. Any excavations resulting from site clearing should be dish-shaped to the lowest depth of disturbance and backfilled under the observation of the geotechnical engineer’s representative.
Building Pad Preparation: The existing surface soil within the proposed house pad areas should be removed to 24 inches below the lowest foundation grades or 48 inches below the existi ng grade (whichever deeper), extending five feet beyond all exterior wall/column lines (including adjacent concrete areas). T he exposed sub-grade should be scarified to a depth o f 8 inches, uniformly moisture conditioned to at least 2% over optimum moisture content and re-compacted to a minimum of 90% of the maximum density determined in accordance with ASTM D1557 methods.
Auxiliary Structures Foundation Preparation: Auxiliary structures such as free standing or retaining walls should have footings extended to a minimum of 24 inches below grade. The existing soil beneath the structure foundat ion prepared in the manner described for the house pad except the preparation needed only to extend 18 inches below and beyond the footing.
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Sidewalk and Concrete Hardscape Areas: In areas other than the building pad which are to receive concrete slabs, the ground surface should be over-excavated to a depth of 8 to 12 inches, uniformly moisture conditioned to at least 2% over optimum moisture, and re-compacted to at least 90% of ASTM D1557 maximum density.
Street Subgrade Preparation: The native soils in street areas should be removed and recompacted to 12 inches below the design subgrade elevation. Engineered fill in street areas should be uniformly moisture conditioned to at least 2% over optimum moisture, placed in layers not more than 6 to 8 inches in thickness and mechanically compacted to a minimum of 90% of the ASTM D1557 maximum dry density.
The native granular soil is suitable for use as compacted fill and utility trench backfill. The native soil should be placed in maximum 8-inch lifts (loose), uniformly moisture conditioned to at least 2% of optimum moisture content and re-compacted to a minimum of 90% of the m aximum density determined in accordance with ASTM D1557 methods.
Imported fill soil (if needed) should be like onsite soil or non-expansive, granular soil meeting the USCS classifications of SM, SP -SM, or SW -SM with a maximum rock s ize of 3 inches. The geotechnical engineer should approve imported fill soil sources before hauling material to the site.
Imported granular fill should be placed in lifts no greater than 8 inches in loose thickness, uniformly moisture conditioned to at least 2% over optimum moisture content and re-compacted to a minimum of 90% of the maximum density determined in accordance with ASTM D1557 methods.
Closure
We have prepared this report for your exclusive use in accordance wit h the genera lly accepted geotechnical engineering practice as it existed within the site area at the time of our study. No warranty is expressed or implied. It should be noted that the submitted plans were not reviewed for conformance with other clients’, governmental or consultant requirements.
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We recommend that Landmark Consultants , Inc. be retained to provide tests and observations services during construction. The geotechnical engineering firm providing such tests and observations shall become the geotechnical engineer of re cord and assume responsibility for the project.
Landmark Consultants, Inc. recommendations for this site are, to a high degree, dependent upon appropriate quality control of subgrade preparation, fill placement, and foundation construction.
Accordingly, the findings and professional opinions in this report are contingent upon the opportunity for Landmark Consultants, Inc. to observe grading oper ations and foundation excavations for the proposed construction.
If parties other than Landmark Consultants, Inc. are engaged to provide observation and testing services during construction, such parties must be notified that they will be required to ass ume complete responsibility as the geotechnical engineer of rec ord for the geotechnical phase of the project by concurring with the recommendations in this report and/or by providing alternative recommendations.
Additional information concerning the scope and cost of these services can be obt ained from our office. We appreciate the opportunity to be of service. Should you have any questions, please call our office at (760)360-0665.
Sincerely Yours,
LandMark Consultants, Inc.
Greg M. Chandra, P.E., M.ASCE
Principal Engineer
October 12, 2016
Mr. Skip Goodell
Desert Care, LLC
31-190 Calle Cayuga
Cathedral City, CA 92234
Geotechnical Report
Living Care Assisted Living
Cathedral City, California
LCI Report No. LP17122
Dear Mr. Goodell:
This geotechnical report is provided for desi gn and construction of the proposed commercial complex located at 30260 Date Palm Drive in Ca thedral City, California. Our geotechnical investigation was conducted in response to your re quest for our services. The enclosed report describes our soil engineering investigation a nd presents our professional opinions regarding geotechnical conditions at the site to be considered in the design and construction of the project.
The findings of this study indicate the site is underlain by sands to maximum depth penetrated. The near surface soils at the project site are expected to be non-expansive. The subsurface soils are medium dense to dense in nature. Groundwater was not encountered in the borings during the time of field exploration. Historic groundwater levels ranged from 130 to 170 feet within the past 65 years in the vicinity of the project site.
Elevated sulfate and chloride levels were not encountered in the soil samples tested for this study.
The soil is low corrosive to metal. We reco mmend a minimum of 2,500 psi concrete of Type II Portland Cement with a maximum water/cement ratio of 0.60 (by weight) should be used for concrete placed in contact with native soils of this project.
We did not encounter soil conditions that would preclude implementation of the proposed project provided the professional opinions contained in this report are implemented in the design and construction of this project. Our findings, professional opinions, and application options are related only through reading the full report , and are best evaluated with the active participation of the engineer of record who developed them.
780 N. 4th Street
El Cent ro, CA 92243
(760) 370-3000
(760) 337-8900 fax
77-948 Wildcat Drive
Palm Desert , CA 92211
(760) 360-0665
(760) 360-0521 fax
a MBE Company
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
TABLE OF CONTENTS
Page
Section 1 ......................................................................................................................................... 1 INTRODUCTION ...................................................................................................................... 1
1.1 Project Description ........................................................................................................... 1
1.2 Purpose and Scope of Work ............................................................................................. 1
1.3 Authorization ................................................................................................................... 2 Section 2 ......................................................................................................................................... 3 METHODS OF INVESTIGATION ........................................................................................... 3
2.1 Field Exploration ............................................................................................................. 3
2.2 Laboratory Testing ........................................................................................................... 4 Section 3 ......................................................................................................................................... 5 DISCUSSION ............................................................................................................................. 5
3.1 Site Conditions ................................................................................................................. 5
3.2 Geologic Setting ............................................................................................................... 5
3.3 Faulting ............................................................................................................................ 6
3.4 General Ground Motion Analysis .................................................................................... 6
3.5 Seismic and Other Hazards .............................................................................................. 7
3.6 Subsurface Soil ................................................................................................................ 8
3.7 Groundwater .................................................................................................................... 8
3.9 Hydro-consolidation ........................................................................................................ 9
3.9 Regional Subsidence ........................................................................................................ 9 Section 4 ....................................................................................................................................... 10 DESIGN CRITERIA ................................................................................................................ 10
4.1 Site Preparation .............................................................................................................. 10
4.2 Foundations and Settlements ......................................................................................... 12
4.3 Slabs-On-Grade .............................................................................................................. 13
4.4 Concrete Mixes and Corrosivity .................................................................................... 14
4.5 Excavations .................................................................................................................... 15
4.6 Lateral Earth Pressures .................................................................................................. 15
4.7 Seismic Design ............................................................................................................... 15
4.7 Permanent Slopes ........................................................................................................... 16
4.8 Pavements ...................................................................................................................... 16 Section 5 ....................................................................................................................................... 18 LIMITATIONS AND ADDITIONAL SERVICES ................................................................. 18
5.1 Limitations ..................................................................................................................... 18
5.2 Additional Services ........................................................................................................ 19
APPENDIX A: Vicinity and Site Maps
APPENDIX B: Subsurface Soil Logs and Soil Key
APPENDIX C: Laboratory Test Results
APPENDIX D: References
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Section 1
INTRODUCTION
1.1 Project Description
This report presents the findings of our geotechnical exploration for the proposed commercial and residential complex located at 30260 Date Palm Drive in the city of Cathedral City, California (See Vicinity Map, Plate A-1). The proposed development will consist of urgent care, senior housing, hotel, restaurant, and administration building on 11 acres of vacant desert land. A site plan for the proposed development was provided by Self Reliance, Inc., dated May 3, 2017.
The structures are planned to consist of conti nuous wall and column concrete footings, concrete slabs-on-grade and wood-frame construction. Footing loads at exterior bearing walls are estimated at 1 to 10 kips per lineal foot. Column loads are estimated to range from 5 to 80 kips. If structural loads exceed those stated above, we should be notified so we may evaluate their impact on foundation settlement and bearing capacity. Site development will include building pad preparation, underground utilities installation, on-site and off-site street construction, concrete driveway and sidewalk placement.
1.2 Purpose and Scope of Work
The purpose of this geotechnical study was to investigate the upper 51.5 feet of subsurface soil at selected locations within the site for evaluati on of physical/engineering properties. From the subsequent field and laboratory data, professional opinions were developed and are provided in this report regarding geotechnical conditions at this site and the effect on design and construction. The scope of our services consisted of the following:
Field exploration and in-situ testing of the site soils at selected locations and depths. Laboratory testing for physical and/or chemical properties of selected samples. Review of the available literature a nd publications pertaining to local geology, faulting, and seismicity.
Engineering analysis and evaluation of the data collected. Preparation of this report presenti ng our findings and, pr ofessional opinions, regarding the geotechnical aspects of project design and construction.
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This report addresses the following geotechnical parameters:
Subsurface soil and groundwater conditions
Site geology, regional faulting and seismicit y, near source factors, and site seismic accelerations
Liquefaction potential and its mitigation
Expansive soil and methods of mitigation
Aggressive soil conditions to metals and concrete
Professional opinions with regard to the above parameters are presented for the following:
Site grading and earthwork
Building pad and foundation subgrade preparation
Allowable soil bearing pressures and expected settlements Concrete slabs-on-grade
Lateral earth pressures
Excavation conditions and buried utility installations Mitigation of the potential effects of salt concentrations in native soil to concrete mixes and steel reinforcement
Seismic design parameters
Preliminary Pavement structural sections
Our scope of work for this report did not include an evaluation of the site for the presence of environmentally hazardous materials or conditions.
1.3 Authorization
Ms. Geri Doodell of Desert Care, LLC provided authorization by written agreement to proceed with our work on August 15, 2017. We conducted our wo rk according to our written proposal dated August 11, 2017.
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Section 2
METHODS OF INVESTIGATION
2.1 Field Exploration
Subsurface exploration was performed on August 31, 2017 using 2R Drilling of Ontario California to advance five (5) borings to depths of 21.5 to 51.5 feet below existing ground surface. The borings were advanced with a truck-mounted, CME 75 drill rig using 8-inch diameter, hollow-stem, continuous-flight augers. The approximate boring locations were established in the field and plotted on the site map by sighting to discernable site features. The boring locations are shown on the Site and Exploration Plan (Plate A-2).
Additional subsurface exploration was performed on September 14, 2017 by using a backhoe to excavate six (6) test pits to an approximate depth of 15 feet below the existing ground surface. The test pit locations are shown on the Site and Exploration Plan (Plate A-2). Bulk samples driven into undisturbed soil were obtained at se lected depths in the test pits. A nuclear densometer (ASTM D6938) was used to evaluate in-situ densities and natural moisture content at selected depths in the upper 5 feet of the backhoe pits. The test pits were located by taped or paced measurements and should be considered approximate.
After logging and sampling the soil, the exploratory boring and test pits were backfilled with the excavated material. The backfill was loosely pl aced and was not compacted to the requirements specified for engineered fill. The backhoe pits shall be located during rough grading of the site to properly re-compact the backfill.
Our senior engineer maintained logs of the borings and test pits during exploration. The logs were edited in final form after a review of retrieved samples and the field and laboratory data. The boring and test pit logs are presented on Plates B-1 through B-11 in Appendix B. Soils encountered have been classified according to the Unified Soil Classification System. A key to the boring and test pit logs is presented on Plate B-12. The stratification lines shown on the subsurface logs represent the approximate boundaries between the various strata. However, the transition from one stratum to another may be gradual over some range of depth.
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2.2 Laboratory Testing
Laboratory tests were conducted on selected bulk and relatively undisturbed soil samples to aid in classification and evaluation of selected engineeri ng properties of the site soils. The tests were conducted in general conformance to the procedur es of the American Society for Testing and Materials (ASTM) or other standardized methods as referenced below. The laboratory testing program consisted of the following tests:
Particle Size Analyses (ASTM D422) – us ed for soil classification and liquefaction evaluation.
Collapse Potential (ASTM D5333) – used for hydro-consolidation potential evaluation.
Unit Dry Densities (ASTM D2937) – used for insitu soil parameters
Moisture Contents (ASTM D2216) – used for insitu soil parameters
Moisture-Density Relationship (ASTM D1557) – used for soil compaction determinations.
Chemical Analyses (soluble sulfates & chlori des, pH, and resistivity) (Caltrans Methods) – used for concrete mix evaluations and corrosion protection requirements.
The laboratory test results are presented on the subsurface logs and on Plates C-1 through C-7 in Appendix C.
Engineering parameters of soil strength, compressibility and relative density utilized for developing design criteria provided within this report were either extrapolated from correlations with the data obtained from the field and laboratory testing program.
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Section 3
DISCUSSION
3.1 Site Conditions
The project site is rectangular shaped in plai n view, is relatively flat-lying and consists of approximately 11 acres of vacant land. The site is bounded by Rosemount Road to the south and Date Palm Drive to the west, residential homes to the east, and the Northgate Community Church to the north. Adjacent properties are flat-lying and are approximately at the same elevation with this site.
The project site lies at an elevation of approximately 360 to 370 feet above mean sea level (MSL) in the Coachella Valley region of the California low desert. Annual rainfall in this arid region is less than 4 inches per year with four months of average summertime temperatures above 100 oF. Winter
temperatures are mild, seldom reaching freezing.
3.2 Geologic Setting
The project site is located in the Coachella Valley portion of the Salton Trough physiographic province. The Salton Trough is a geologic structural depression resulting from large scale regional faulting. The trough is bounded on the northeast by the San Andreas Fault and Chocolate Mountains and the southwest by the Peninsular Range and fau lts of the San Jacinto Fault Zone. The Salton Trough represents the northward extension of the Gulf of California, containing both marine and non-marine sediments since the Miocene Epoch. Tectonic activity that formed the trough continues at a high rate as evidenced by deformed young sedimentary deposits and high levels of seismicity.
Figure 1 shows the location of the site in relation to regional faults and physiographic features.
The surrounding regional geology includes the Penins ular Ranges (Santa Rosa and San Jacinto Mountains) to the south and west, the Salton Basi n to the southeast, and the Transverse Ranges (Little San Bernardino and Orocopia Mountains) to the north and east. Hundreds of feet to several thousand feet of Quaternary fluvial, lacustrine , and aeolian soil deposits underlie the Coachella Valley.
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The southeastern part of the Coachella Valley lies below sea level. In the geologic past, the ancient Lake Cahuilla submerged the area. Calcareous tufa deposits may be observed along the ancient shoreline as high as elevation 45 to 50 feet MSL along the Santa Rosa Mountains from La Quinta southward. Lacustrine (lake bed) deposits comprise the subsurface soils over much of the eastern Coachella Valley with alluvial outwash along the flanks of the valley.
3.3 Faulting
The project site is located in the seismically ac tive Coachella Valley of southern California with numerous mapped faults of the San Andreas Fault System traversing the region. We have performed a computer-aided search of known faults or seismic zones that lie within a 62-mile (100 kilometer) radius of the project site (Table 1).
A fault map illustrating known active faults relative to the site is presented on Figure 1, Regional Fault Map . Figure 2 shows the project site in relati on to local faults. The criterion for fault classification adopted by the California Geological Survey defines Earthquake Fault Zones along active or potentially active faults. An active fau lt is one that has ruptured during Holocene time (roughly within the last 11,000 years). A fault that has ruptured during the last 1.8 million years (Quaternary time), but has not been proven by direct evidence to have not moved within Holocene time is considered to be potentially active. A fault that has not moved during Quaternary time is considered to be inactive.
Review of the current Alquist-Priolo Earthquake Fault Zone maps (CGS, 2000a) indicates that the nearest mapped Earthquake Fault Zone is the San Andreas Fault located approximately 3.7 miles northeast of the project site.
3.4 General Ground Motion Analysis
The project site is considered likely to be s ubjected to moderate to strong ground motion from earthquakes in the region. Ground motions are dependent primarily on the earthquake magnitude and distance to the seismogenic (rupture) zone.
Loving Care Assisted Living - Cathedral City, CA LCI Project No. LP17122 Table 1
Fault Name
Approximate
Distance
(miles)
Approximate
Distance (km)
Maximum
Moment
Magnitude
(Mw)
Fault Length
(km)
Slip Rate
(mm/yr)
Garnet Hill * 1.0 1.6
San Andreas - San Bernardino (South) 3.7 6.0 7.4 103 ± 10 30 ± 7 San Andreas - San Bernardino (North) 5.6 9.0 7.5 103 ± 10 24 ± 6 Eureka Peak 12.0 19.2 6.4 19 ± 2 0.6 ± 0.4
Indio Hills * 12.7 20.3
Blue Cut * 12.9 20.6
San Andreas - Coachella 13.3 21.2 7.2 96 ± 10 25 ± 5
Burnt Mtn. 16.0 25.6 6.5 21 ± 2 0.6 ± 0.4
Morongo * 16.3 26.1
Pinto Mtn. 18.6 29.8 7.2 74 ± 7 2.5 ± 2
San Jacinto - Anza 20.8 33.3 7.2 91 ± 9 12 ± 6
Landers 23.3 37.2 7.3 83 ± 8 0.6 ± 0.4
San Jacinto - Coyote Creek 25.6 41.0 6.8 41 ± 4 4 ± 2
San Jacinto - San Jacinto Valley 27.7 44.3 6.9 43 ± 4 12 ± 6 Johnson Valley (northern) 32.5 52.0 6.7 35 ± 4 0.6 ± 0.4 Pisgah Mtn. - Mesquite Lake 33.0 52.8 7.3 89 ± 9 0.6 ± 0.4 North Frontal Fault Zone - Eastern 33.2 53.2 6.7 27 ± 3 0.5 ± 0.3 S. Emerson - Copper Mtn. 33.6 53.8 7 54 ± 5 0.6 ± 0.4
Lenwood - Lockhart - Old Woman Springs 37.5 60.1 7.5 145 ± 15 0.6 ± 0.4 North Frontal Fault Zone - Western 40.0 63.9 7.2 51 ± 5 1 ± 0.5 Calico-Hidalgo 40.1 64.2 7.3 95 ± 10 0.6 ± 0.4
Helendale - S. Lockhart 44.0 70.3 7.3 97 ± 10 0.6 ± 0.4 * Note: Faults not included in CGS database.
Summary of Characteristics of Closest Known Active Faults Project No.: 17122LP Regional Fault Map Figure 1
Source: California Geological Survey 2010 Fault Activity Map of California http://www.quake.ca.gov/gmaps/ /faultactivitymap.html#FAM N
100 km
Project No.: 17122LP Map of Local Faults Figure 2
Source: California Geological Survey 2010 Fault Activity Map of California http://www.quake.ca.gov/gmaps/ /faultactivitymap.html#FAM Project Site
N
Project No.: LP17122
Fault Map Legend Figure
3a
Project No.: 17122LP
Fault Map Legend Figure
3b
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Acceleration magnitudes also are dependent upon attenuation by rock and soil deposits, direction of rupture and type of fault; therefore, ground motions may vary considerably in the same general area.
CBC General Ground Motion Parameters: The 2016 CBC general ground motion parameters are based on the Risk-Targeted Maximum Considered Earthquake (MCE R). The U.S. Geological Survey “U.S. Seismic Design Maps Web Applicati on” (USGS, 2017) was used to obtain the site coefficients and adjusted maximum consid ered earthquake spectral response acceleration parameters. The site soils have been classified as Site Class D (stiff soil profile). Design spectral response acceleration parameters are defined as the earthquake ground motions that are two-thirds (2/3) of the corresponding MCER ground motions. Design earthquake ground motion parameters are provided in Table 2. A Risk Category II was determined using Table 1604.5 and the Seismic Design Category is E since S
1 is greater than 0.75.
The Maximum Considered Earthquake Geometric Mean (MCE
G) peak ground acceleration (PGAM)
value was determined from the “U.S. Seismic Design Maps Web Application” (USGS, 2017) for liquefaction and seismic settlement analysis in accordance with 2016 CBC Section 1803.5.12 and CGS Note 48 (PGAM = FPGA*PGA). A PGAM value of 0.85g is used for liquefaction settlement analysis.
3.5 Seismic and Other Hazards
► Groundshaking. The primary seismic hazard at the project site is the potential for strong groundshaking during earthquakes along the San A ndreas Fault. A further discussion of groundshaking follows in Section 3.4.
► Surface Rupture. The project site does not lie within a State of California, Alquist-Priolo Earthquake Fault Zone. Surface fault rupture is considered to be unlikely at the project site because of the well-delineated fault lines through the Coachella Valley as shown on USGS and CDMG maps.
However, because of the high tectonic activity and deep alluvium of the region, we cannot preclude the potential for surface rupture on undiscovered or new faults that may underlie the site. ► Liquefaction. Liquefaction is unlikely to be a potential hazard at the site, since the groundwater is believed to be deeper than 50 feet (the maximum depth that liquefaction is known to occur).
Loving Care Assisted Living - Cathedral City, CA LCI Project No. LP17122 CBC Reference
Soil Site Class: D Table 20.3-1
Latitude: 33.8283 N
Longitude: -116.4569 W
Risk Category: II
Seismic Design Category:E
Maximum Considered Earthquake (MCE) Ground Motion
Mapped MCER Short Period Spectral Response Ss 2.191 g Figure 1613.3.1(1) Mapped MCER 1 second Spectral Response S1 1.072 g Figure 1613.3.1(2) Short Period (0.2 s) Site Coefficient Fa 1.00 Table 1613.3.3(1) Long Period (1.0 s) Site Coefficient Fv 1.50 Table 1613.3.3(2) MCER Spectral Response Acceleration Parameter (0.2 s) SMS 2.191 g = F a * Ss MCER Spectral Response Acceleration Parameter (1.0 s) SM1 1.608 g = F v * S1 Design Earthquake Ground Motion
Design Spectral Response Acceleration Parameter (0.2 s) SDS 1.461 g = 2/3*S MS Design Spectral Response Acceleration Parameter (1.0 s) SD1 1.072 g = 2/3*S M1 Risk Coefficient at Short Periods (less than 0.2 s) CRS 0.963 Risk Coefficient at Long Periods (greater than 1.0 s) CR1 0.914 TL 8.00 sec
TO 0.15 sec =0.2*SD1/SDS
TS 0.73 sec =SD1/SDS
Peak Ground Acceleration PGAM 0.85 g
Period Sa MCE R Sa
T (sec) (g) (g)
0.00 0.58 0.88
0.15 1.46 2.19
0.73 1.46 2.19
1.05 1.02 1.53
1.06 1.01 1.52
1.07 1.00 1.50
1.08 0.99 1.49
1.10 0.97 1.46
1.20 0.89 1.34
1.20 0.89 1.34
1.40 0.77 1.15
1.50 0.71 1.07
1.75 0.61 0.92
2.00 0.54 0.80
2.20 0.49 0.73
2.40 0.45 0.67
2.60 0.41 0.62
2.80 0.38 0.57
3.00 0.36 0.54
3.50 0.31 0.46
4.00 0.27 0.40
ASCE Equation 11.8-1
Equation 16-40
ASCE Figure 22-12
Table 2
2016 California Building Code (CBC) and ASCE 7-10 Seismic Parameters Equation 16-37
Equation 16-38
Equation 16-39
ASCE Figure 22-17
ASCE Figure 22-18
0.0 0.2
0.4 0.6
0.8 1.0
1.2 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Spectral Acceleration, Sa (g)
Period (sec)
Generalized Design Response Spectrum
(ASCE 7-5 Section 11.4.5)
0.0 0.5
1.0 1.5
2.0 2.5
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Spectral Acceleration, Sa (g)
Period (sec)
MCER Response Spectra Design Response Spectra
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
LandMark Consultants, Inc. Page 8
Other Potential Geologic Hazards.
► Landsliding. The hazard of landsliding is unlikely due to the regional planar topography. No ancient landslides are shown on geologic maps of the region and no indications of landslides were observed during our site investigation.
► Volcanic hazards. The site is not located in proximity to any known volcanically active area and the risk of volcanic hazards is considered very low.
► Tsunamis, sieches, and flooding. The site does not lie near any large bodies of water, so the threat of tsunami, sieches, or other seismically-i nduced flooding is unlikely. The project site is located within a Federal Emergency Management Agency (FEMA) Other Flood Areas Zone X (as shown on Plate A-6).
► Expansive soil. The near surface soils at the project site consist of sands which are non-expansive in nature.
3.6 Subsurface Soil
Subsurface soils encountered during the field exploration conducted on August 31 and September 14, 2017 consist of medium dense to dense sands to maximum depth penetrated. The near surface soils are non-expansive in nature. The subsur face logs (Plates B-1 through B-11) depict the stratigraphic relationships of the various soil types.
3.7 Groundwater
Groundwater was not encountered in the test pits during the time of exploration. According to Coachella Valley Water District (CVWD) readi ngs of groundwater levels from nearby wells, groundwater is located at a depth of approximately 230 feet below the ground surface in the vicinity of the project site.
There is uncertainty in the accuracy of short-term water level measurements, particularly in fine- grained soil. Groundwater levels may fluctuate with precipitation, irrigation of adjacent properties, drainage, and site grading. The groundwater level noted should not be interpreted to represent an accurate or permanent condition.
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
LandMark Consultants, Inc. Page 9
Based on the general topography, groundwater flow di rections are estimated to be toward the southeast within the subject site area. Flow directions may also vary locally in the vicinity of the site.
Historic groundwater records in the vicinity of the project site indicate that groundwater has fluctuated between 130 to 170 feet below the ground surface over the last 65 years according to the Coachella Valley Water District and to a report "Coachella Valley Investigation" conducted by the Department of Water Resources, published July 1964.
3.8 Hydro-consolidation
In arid climatic regions, granular soils have a potential to collapse upon wetting. This collapse (hydro-consolidation) phenomena is the result of the lubrication of soluble cements (carbonates) in the soil matrix causing the soil to densify from its loose configuration during deposition.
Collapse potential tests (Plates C-7) performed on a remolded sample from the site indicated a slight risk of collapse upon saturation. Therefore, development of building foundation is not required to include provisions for mitigating the hydro-consolidation caused by soil saturation from landscape irrigation or broken utility lines.
3.9 Regional Subsidence
The project is located in the Coachella Valley wh ich has experienced up to 12 inches of regional subsidence between 1996 and 2005 (USGS, 2007). The risk of regional subsidence at the project site is considered low.
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
LandMark Consultants, Inc. Page 10
Section 4
DESIGN CRITERIA
4.1 Site Preparation
Pre-grade Meeting: Prior to site preparation, a meeting should be held at the site with as a minimum, the owner’s representative, grading contractor and geotechnical engineer in attendance.
Clearing and Grubbing: All surface improvements, debris and/or vegetation including grass, trees, and weeds on the site at the time of construction should be removed from the construction area.
Root balls should be completely excavated. Organic stripping should be hauled from the site and not used as fill. Any trash, construction debris, concrete slabs, old pavement, and buried obstructions such as old foundations and utility lines exposed during rough grading should be traced to the limits of the foreign materials and removed . Any excavations resulting from site clearing and grubbing should be dish-shaped to the lowest depth of disturbance and backfilled with engineered fill.
Building Pad Preparation: The existing surface soil within the building pad areas should be removed to 24 inches below the lowest foundation grade or 48 inches below the original grade (whichever is deeper), extending five feet beyond all exterior wall/column lines (including adjacent concreted areas). The exposed sub-grade should be scarifie d to a depth of 8 inches, uniformly moisture conditioned to at least 2% over optimum moisture , and re-compacted to at least 90% of ASTM D1557 maximum density
The on-site soils are suitable for use as compacted fill and utility trench backfill. Imported fill soil (if required) should similar to onsite soil or non-expansive, granular soil meeting the USCS classifications of SM, SP-SM, or SW-SM with a maximum rock size of 3 inches. The geotechnical engineer should approve imported fill soil sour ces before hauling material to the site . Native, stock pile and imported materials should be placed in lifts no greater th an 8 inches in loose thickness, uniformly moisture conditioned to at least 2% over optimum moisture, and re-compacted to at least 90% of ASTM D1557 maximum density.
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
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In areas other than the building pad which are to receive concrete slabs and asphalt concrete pavement, the ground surface should be over-excavated to a depth of 12 inches, uniformly moisture conditioned to at least 2% over optimum moisture , and re-compacted to at least 90% of ASTM D1557 maximum density.
Trench Backfill: On-site soil free of debris, vegetation, and other deleterious matter may be suitable for use as utility trench backfill. Backfill within roadways should be placed in layers not more that 6 inches in thickness, uniformly moisture conditi oned to at least 2% over optimum moisture and mechanically compacted to a minimum of 90% of the ASTM D1557 maximum dry density except for the top 12 inches of the trench which shall be compacted to at least 95%. Native backfill should only be placed and compacted after encapsulati ng buried pipes with suitable bedding and pipe envelope material.
Pipe envelope/bedding should either be clean sand (Sand Equivalent SE>30) or crushed rock when encountering groundwater. A geotextile filter fabric (Mirafi 140N or equivalent) should be used to encapsulate the crushed rock to reduce the potentia l for in-washing of fines into the gravel void space. Precautions should be taken in the compaction of the backfill to avoid damage to the pipes and structures.
Moisture Control and Drainage: The moisture condition of the building pad should be maintained during trenching and utility installation until conc rete is placed or should be rewetted before initiating delayed construction. If soil drying is noted, a 2 to 3 inches depth of water may be used in the bottom of footings to restore footing subgrade moisture and reduce potential edge lift.
Adequate site drainage is essential to future performance of the project. Infiltration of excess irrigation water and stormwaters can adversely affect the performance of the subsurface soil at the site. Positive drainage should be maintained aw ay from all structures (5% for 5 feet minimum across unpaved areas) to prevent ponding and subsequent saturation of the native soil. Gutters and downspouts may be considered as a means to convey water away from foundations. If landscape irrigation is allowed next to the building, drip irrigation systems or lined planter boxes should be used. The subgrade soil should be maintained in a moist, but not saturated state, and not allowed to dry out. Drainage should be maintained without ponding.
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
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Observation and Density Testing: All site pr eparation and fill placement should be continuously observed and tested by a representative of a qua lified geotechnical engineering firm. Full-time observation services during the excavation and scar ification process is necessary to detect un- desirable materials or conditions and soft areas th at may be encountered in the construction area.
The geotechnical firm that provides observation a nd testing during construction shall assume the responsibility of "geotechnical engineer of record" and, as such, shall perform additional tests and investigation as necessary to satisfy themselves as to the site conditions and the recommendations for site development.
Auxiliary Structures Foundation Preparation: Auxiliary structures such as free standing or retaining walls should have the existing soil beneath the structure foundation prepared in the manner recommended for the building pad except the preparation needed only to extend 18 inches below and beyond the footing.
4.2 Foundations and Settlements
Shallow column footings and continuous wall footings are suitable to support the structures provided they are founded on a layer of properly prepared and compacted soil as described in Section 4.1.
The foundations may be designed using an allowa ble soil bearing pressure of 1,800 psf. The allowable soil pressure may be increased by 20% for each foot of embedment depth in excess of 18 inches and by one-third for short term loads induced by winds or seismic events. The maximum allowable soil pressure at increased embedment depths shall not exceed 2,800 psf.
All exterior and interior foundations should be embedded a minimum of 18 inches below the building support pad or lowest adjacent final grade, whichever is deeper. Continuous wall footings should have a minimum width of 12 inches. Column footings should have a minimum width of 24 inches and should not be structurally isolated. Recommended concrete reinforcement and sizing for all footings should be provided by the structural engineer.
Resistance to horizontal loads will be developed by passive earth pressure on the sides of footings and frictional resistance developed along the bases of footings and concrete slabs. Passive resistance to lateral earth pressure may be calculated using an equivalent fluid pressu re of 300 pcf to resist lateral loadings.
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
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The top one foot of embedment should not be considered in computing passive resistance unless the adjacent area is confined by a slab or pavement. An allowable friction coefficient of 0.4 may also be used at the base of the footings to resist lateral loading.
Foundation movement under the estimated static (non-seismic) loadings and static site conditions are estimated to not exceed ¾ inch with differential movement of about two-thirds of total movement for the loading assumptions stated above when the subgrade preparation guidelines given above are followed.
4.3 Slabs-On-Grade
Concrete slabs and flatwork should be a minimum of 4 inches thick. Concrete slabs and flatworks should be determined by the design engineer. Conc rete floor slabs may either be monolithically placed with the foundation or dowelled after footing placement. The concrete slabs may be placed on granular subgrade that has been compacted at least 90% relative compaction (ASTM D1557).
American Concrete Institute (ACI) guidelines (ACI 302.1R-04 Chapter 3, Section 3.2.3) provide recommendations regarding the use of moisture barriers beneath concrete slabs. The concrete floor slabs should be underlain by a 10-mil polyethylene vapor retarder that works as a capillary break to reduce moisture migration into the slab section. All laps and seams should be overlapped 6-inches or as recommended by the manufacturer. The vapor retarder should be protected from puncture.
The joints and penetrations should be sealed with the manufacturer’s recommended adhesive, pressure-sensitive tape, or both. The vapor retarder should extend a minimum of 12 inches into the footing excavations. The vapor retarder shoul d be covered by 4 inches of clean sand (Sand Equivalent SE>30) unless placed on 2.5 feet of granular fill, in which case, the vapor retarder may lie directly on the granular fill with 2 inches of clean sand cover.
Placing sand over the vapor retarder may increase moisture transmission through the slab, because it provides a reservoir for bleed water from the concrete to collect. The sand placed over the vapor retarder may also move and mound prior to conc rete placement, resulting in an irregular slab thickness.
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
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For areas with moisture sensitive flooring materials, ACI recommends that concrete slabs be placed without a sand cover directly over the vapor retard er, provided that the concrete mix uses a low- water cement ratio and concrete curing methods are employed to compensate for release of bleed water through the top of the slab. The vapor retarder should have a minimum thickness of 15-mil (Stego-Wrap or equivalent).
Control joints should be provided in all concrete slabs-on-grade at a maximum spacing (in feet) of 2 to 3 times the slab thickness (in inches) as r ecommended by American Concrete Institute (ACI) guidelines. All joints should form approximately square patterns to reduce randomly oriented contraction cracks. Contraction joints in the slabs should be tooled at the time of the pour or sawcut (¼ of slab depth) within 6 to 8 hours of conc rete placement. Construction (cold) joints in foundations and area flatwork should either be th ickened butt-joints with dowels or a thickened keyed-joint designed to resist vertical deflection at the joint. All joints in flatwork should be sealed to prevent moisture, vermin, or foreign material intrusion. Precautions should be taken to prevent curling of slabs in this arid desert region (refer to ACI guidelines).
All independent concrete flatworks should be underlain by 12 inches of moisture conditioned and compacted soils. All flatwork should be jointed in square patterns and at irregularities in shape at a maximum spacing of 10 feet or the least width of the sidewalk.
4.4 Concrete Mixes and Corrosivity
Selected chemical analyses for corrosivity were conducted on bulk samples of the near surface soil from the project site (Plate C-5). The native soils tested were shown to have low levels of sulfate and chloride ion concentrations. Resistivity de terminations on the soil indicate low potential for metal loss because of electrochemical corrosion processes.
A minimum of 2,500 psi concrete of Type II Portland Cement with a maximum water/cement ratio of 0.60 (by weight) should be used for concrete pl aced in contact with native soil on this project (sitework including streets, sidewalks, driveways, patios, and foundations).
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
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A minimum concrete cover of three (3) inch es is recommended around steel reinforcing or embedded components (anchor bolts, hold-downs, etc.) exposed to native soil or landscape water (to 18 inches above grade). The concrete should also be thoroughly vibrated during placement.
Landmark does not practice corrosion engineering. We recommend that a qualified corrosion engineer evaluate the corrosion potential on metal construction materials and concrete at the site.
4.5 Excavations
All trench excavations should conform to CalOSHA requirements for Type C soil. The contractor is solely responsible for the safety of workers entering trenches. Temporary excavations with depths of 4 feet or less may be cut nearly vertical for short duration. Temporary slopes should be no steeper than 1.5:1 (horizontal: vertical). Sandy soil slopes should be kept moist, but not saturated, to reduce the potential of raveling or sloughing.
Trench excavations deeper than 4 feet will require shoring or slope inclinations in conformance to CAL/OSHA regulations for Type C soil. Surcharge loads of stockpiled soil or construction materials should be set back from the top of the slope a minimum distance equal to the height of the slope. All permanent slopes should not be steeper than 3:1 to reduce wind and rain erosion.
Protected slopes with ground cover may be as steep as 2:1. However, maintenance with motorized equipment may not be possible at this inclination.
4.6 Lateral Earth Pressures
Earth retaining structures, such as retaining walls , should be designed to resist the soil pressure imposed by the retained soil mass. Walls with gr anular drained backfill may be designed for an assumed static earth pressure equivalent to that exerted by a fluid weighing 35 pcf for unrestrained (active) conditions (able to rotate 0.1% of wall height), and 50 pcf for restrained (at-rest) conditions.
These values should be verified at the actual wall locations during construction.
4.7 Seismic Design
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
LandMark Consultants, Inc. Page 16
This site is located in the seismically active s outhern California area and the site structures are subject to strong ground shaking due to potential fault movements along the San Andreas fault.
Engineered design and earthquake-resistant construction are the common solutions to increase safety and development of seismic areas. Designs should comply with the latest edition of the CBC for Site Class D using the seismic coefficients given in Section 3.4 of this report.
4.8 Permanent Slopes
Cut and Fill slopes should be constructed genera lly no steeper than 3 (H):1(V) to permit easy landscape maintenance and provide erosional stability form wind or rain while unprotected without landscape cover. Slope with a 2(H):1(V) gradient are permitted provided, it is recognized that such slopes are more prone to erosion and so not permit landscape maintenance by motorized riding equipment, and require landscape cover to retard erosion.
4.9 Pavements
Pavements should be designed according to CA LTRANS or other acceptable methods. Traffic indices were not provided by the project engineer or owner; therefore, we have provided structural sections for several traffic indices for comparative evaluation. The public agency or design engineer should decide the appropriate traffic index for the site. Maintenance of proper drainage is necessary to prolong the service life of the pavements.
Based on the current State of California CALTRANS method, an estimated R-value of 60 for the subgrade soil and assumed traffic indices, the following table provides our estimates for asphaltic concrete (AC) pavement sections.
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
LandMark Consultants, Inc. Page 17
RECOMMENDED PAVEMENTS SECTIONS
R-Value of Subgrade Soil - 60 (estimated) Design Method - CALTRANS 2012 Flexible Pavements
Traffic
Index
(assumed)
Asphaltic
Concrete
Thickness
(in.)
Aggregate
Base
Thickness
(in.)
5.0 3.0 4.0
6.0 3.5 4.0
7.0 4.5 4.0
8.0 5.0 5.5
Notes:
1) Asphaltic concrete shall be Ca ltrans, Type B, ¾ inch maximum medium grading, (½ inch for parking areas) compacted to a minimum of 95% of the 50-blow Marshall density (ASTM D1559).
2) Aggregate base shall conform to Caltran s Class 2 (¾ in. maximum), compacted to a minimum of 95% of ASTM D1557 maximum dry density.
3) Place pavements on 8 inches of moisture c onditioned (at least 2% of over optimum) native soil compacted to a minimum of 90% of th e maximum dry density determined by ASTM D1557, or the governing agency requirements.
Final recommended pavement sections may need to be based on sampling and R-Value testing during grading operations when actual subgrade soils will be exposed.
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
LandMark Consultants, Inc. Page 18
Section 5
LIMITATIONS AND ADDITIONAL SERVICES
5.1 Limitations
The findings and professional opinions within this report are based on current information regarding the proposed commercial complex, located at 30260 Date Palm Drive in the city of Cathedral City, California. The conclusions and professional opinions of this report are invalid if:
Proposed building(s) location and size are changed from those shown in this report < Structural loads change from those stated or the structures are relocated. The Additional Services section of this report is not followed. This report is used for adjacent or other property.
Changes of grade or groundwater occur between the issuance of this report and construction other than those anticipated in this report. Any other change that materially alters th e project from that proposed at the time this report was prepared.
Findings and professional opinions in this report are based on selected points of field exploration, geologic literature, laboratory testing, and our understanding of the proposed project. Our analysis of data and professional opinions presented herein are based on the assumption that soil conditions do not vary significantly from those found at speci fic exploratory locations. Variations in soil conditions can exist between and beyond the exploration points or groundwater elevations may change. If detected, these conditions may requi re additional studies, consultation, and possible design revisions.
This report contains information that may be useful in the preparation of contract specifications.
However, the report is not worded is such a manner that we recommend its use as a construction specification document without proper modification. The use of information contained in this report for bidding purposes should be done at the contractor’s option and risk.
This report was prepared according to the generally accepted geotechnical engineering standards of practice that existed in Riverside County at the time the report was prepared. No express or implied warranties are made in connection with our services.
Loving Care Assisted Living – Cathedral City, CA LCI Report No. LP17122
LandMark Consultants, Inc. Page 19
This report should be considered invalid for periods after two years from the report date without a review of the validity of the findings and professional opinions by our firm, because of potential changes in the Geotechnical Engineering Standards of Practice.
The client has responsibility to see that all parties to the project including, designer, contractor, and subcontractor are made aware of this entire report. The use of information contained in this report for bidding purposes should be done at the contractor's option and risk.
5.2 Additional Services
We recommend that a qualified geotechnical consu ltant be retained to provide the tests and observations services during construction. The geotechnical engineering firm providing such tests and observations shall become the geotechnical engineer of record and assume responsibility for the project.
The professional opinions presented in this report are based on the assumption that:
Consultation during development of design and construction documents to check that the geotechnical professional opinions are appropriate for the proposed project and that the geotechnical professional opinions are properl y interpreted and incorporated into the documents.
LandMark Consultants, Inc. will have the opportunity to review and comment on the plans and specifications for the project prior to the issuance of such for bidding. Continuous observation, inspection, and testing by the geotechnical consultant of record during site clearing, grading, excavation, placement of fills, building pad and subgrade preparation, and backfilling of utility trenches.
Observation of foundation excavations and re inforcing steel before concrete placement. Other consultation as necessary during design and construction.
We emphasize our review of the project plans and specifications to check for compatibility with our professional opinions and conclusions. Additional information concerning the scope and cost of these services can be obtained from our office.
APPENDIX A
Project No.: LP17122 Vicinity Map
Plate
A-1
Project Site
N
LMAND ARK
Geo-Engineers and Geologists
Project No.: LP17122
Plate
A-2
Approximate Boring Location
Approximate Test Pit Location
Legend N
LMAND ARK
Geo-Engineers and Geologists
Site and Exploration Plan
B-2
B-1
T-1
T-2
T-3
T-4
T-5
T-6
B-3
B-4
B-5
Project No.: LP17122
USDA Soil Conservation
Soil Service Map
Plate
A-3
LMAND ARK
Geo-Engineers and Geologists
N
Project Site
Map Unit Legend
Riverside County, Coachella Valley Area, California (CA680) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI MaB Myoma fine sand, 0 to 5
percent slopes
88.6 100.0%
Totals for Area of Interest 88.6 100.0%
Soil Map—Riverside County, Coachella Valley Area, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
9/27/2017
Project No.: LP17122 Topographic Map
Plate
A-4
N
LMAND ARK
Geo-Engineers and Geologists
Project Site
Project No.: LP17122
Riverside County
Geographic Information System (GIS)
Fault Map
Plate
A-5
Project Site
LMAND ARK
Geo-Engineers and Geologists
Project No.: LP17122
FEMA Flood Zones Plate
A-6
Project Site
LMAND ARK
Geo-Engineers and Geologists
APPENDIX B
DATE DRILLED:
LOGGED BY:
TOTAL DEPTH:
SURFACE ELEVATION:
TYPE OF BIT: DIAMETER:
HAMMER WT.: DROP:
DEPTH TO WATER:
LOG OF BORING No. B-1
DEPTH
SAMPLE DESCRIPTION OF MATERIAL
FIELD
PROJECTPROJECT NNOO.. LLP1712217122
60 10
5 20
30 25
30 18
31 41
50/6”
44 19
27 18
21 35
45 55
15 40
50 LABORATORY
DRYDENSITY(pcf) MOISTURE CONTENT(% dry wt.)
OTHER TESTS
BLOW COUNT
SHEET OF11
8/31/17
G. Chandra
Approximately 370'
Hollow Stem
Auger
140 lbs.
8 in.
30 in.
NA51.5 Feet
Total Depth = 51.5'
Groundwater not encountered at time of drilling
Backfilled with excavated soil
SAND M(SP-S ): Grayish brown, dry, fine grained,
medium dense to dense
SAND M(SP-S ): Grayish brown, dry, fine grained, very dense, some gravel
SILTY SAND M(S ): Grayish brown, dry, fine grained, very dense 107.3
0.3 1.9
115.0 1.0
0.6 0.3
1.4 1.4
3.0 0.6
PLATE B-1
USCS
.
CLASS POCKET
. (tsf)
PEN
Passing #200 = 7.1%
Passing #200 = 9.2%
Passing #200 = 7.2%
Passing #200 = 8.1%
Passing #200 = 18.1%
Passing #200 = 5.6%
DATE DRILLED:
LOGGED BY:
TOTAL DEPTH:
SURFACE ELEVATION:
TYPE OF BIT: DIAMETER:
HAMMER WT.: DROP:
DEPTH TO WATER:
LOG OF BORING No. B-2
DEPTH
SAMPLE DESCRIPTION OF MATERIAL
FIELD
PROJECTPROJECT NNOO.. LLP1712217122
60 10
5 20
30 25
26 33
42 12
24 35
45 55
15 40
50 LABORATORY
DRYDENSITY(pcf) MOISTURE CONTENT(% dry wt.)
OTHER TESTS
BLOW COUNT
SHEET OF11
8/31/17
G. Chandra
Approximately 370'
Hollow Stem
Auger
140 lbs.
8 in.
30 in.
NA26.5 Feet
Total Depth = 26.5'
Groundwater not encountered at time of drilling
Backfilled with excavated soil
SAND M(SP-S ): Grayish brown, dry, fine grained,
medium dense to dense
SAND M(SP-S ): Grayish brown, dry, fine grained,
medium dense to dense
SILTY SAND M(S ): Grayish brown, dry, fine grained, dense 107.8
1.7 0.6
106.0 8.5
0.9 PLATE B-2
USCS
.
CLASS POCKET
. (tsf)
PEN
Passing #200 = 10.3%
Passing #200 = 15.5%
DATE DRILLED:
LOGGED BY:
TOTAL DEPTH:
SURFACE ELEVATION:
TYPE OF BIT: DIAMETER:
HAMMER WT.: DROP:
DEPTH TO WATER:
LOG OF BORING No. B-3
DEPTH
SAMPLE DESCRIPTION OF MATERIAL
FIELD
PROJECTPROJECT NNOO.. LP1712217122
60 10
5 20
30 25
18 22
19 64
22 26
9 22
35 45
55 15
40 50
LABORATORY
DRYDENSITY(pcf) MOISTURE CONTENT(% dry wt.)
OTHER TESTS
BLOW COUNT
SHEET OF11
8/31/17
G. Chandra
Approximately 370'
Hollow Stem
Auger
140 lbs.
8 in.
30 in.
NA41.5 Feet
Total Depth = 41.5'
Groundwater not encountered at time of drilling
Backfilled with excavated soil
SAND M(SP-S ): Grayish brown, dry, fine grained,
medium dense
SAND M(SP-S ): Grayish brown, dry, fine grained,
medium dense to dense
SILTY SAND M(S ): Grayish brown, dry, fine grained, loose trace gravel
96.5 2.1
1.5 85.5 0.6
0.7 0.5
0.4 0.8
0.2 PLATE B-3
USCS
.
CLASS POCKET
. (tsf)
PEN
Passing #200 = 15.3%
Passing #200 = 7.1%
Passing #200 = 4.1%
Passing #200 = 7.0%
DATE DRILLED:
LOGGED BY:
TOTAL DEPTH:
SURFACE ELEVATION:
TYPE OF BIT: DIAMETER:
HAMMER WT.: DROP:
DEPTH TO WATER:
LOG OF BORING No. B-4
DEPTH
SAMPLE DESCRIPTION OF MATERIAL
FIELD
PROJECTPROJECT NNOO.. LLP1712217122
60 10
5 20
30 25
25 32
10 22
35 45
55 15
40 50
LABORATORY
DRYDENSITY(pcf) MOISTURE CONTENT(% dry wt.)
OTHER TESTS
BLOW COUNT
SHEET OF11
8/31/17
G. Chandra
Approximately 370'
Hollow Stem
Auger
140 lbs.
8 in.
30 in.
NA21.5 Feet
Total Depth = 21.5'
Groundwater not encountered at time of drilling
Backfilled with excavated soil
SAND M(SP-S ): Grayish brown, dry, fine grained,
medium dense
SAND M(SP-S ): Grayish brown, dry, fine grained,
medium dense
SILTY SAND M(S ): Grayish brown, dry, fine grained, dense 114.8
1.9 0.6
111.1 3.8
0.6 PLATE B-4
USCS
.
CLASS POCKET
. (tsf)
PEN
Passing #200 = 7.5%
Passing #200 = 26.0%
DATE DRILLED:
LOGGED BY:
TOTAL DEPTH:
SURFACE ELEVATION:
TYPE OF BIT: DIAMETER:
HAMMER WT.: DROP:
DEPTH TO WATER:
LOG OF BORING No. B-5
DEPTH
SAMPLE DESCRIPTION OF MATERIAL
FIELD
PROJECTPROJECT NNOO.. LLP1712217122
60 10
5 20
30 25
29 27
13 22
35 45
55 15
40 50
LABORATORY
DRYDENSITY(pcf) MOISTURE CONTENT(% dry wt.)
OTHER TESTS
BLOW COUNT
SHEET OF11
8/31/17
G. Chandra
Approximately 370'
Hollow Stem
Auger
140 lbs.
8 in.
30 in.
NA21.5 Feet
Total Depth = 21.5'
Groundwater not encountered at time of drilling
Backfilled with excavated soil
SAND M(SP-S ): Grayish brown, dry, fine grained,
medium dense to dense
SAND M(SP-S ): Grayish brown, dry, fine grained,
medium dense to dense
SILTY SAND M(S ): Grayish brown, dry, fine grained, dense 104.7
4.2 2.2
105.5 1.1
0.4 PLATE B-5
USCS
.
CLASS POCKET
. (tsf)
PEN
Passing #200 = 32.0%
Passing #200 = 6.9%
DATE EXCAVATED:
LOGGED BY:
TOTAL DEPTH:
SURFACE ELEVATION:
TYPE OF BIT: DIAMETER:
HAMMER WT.: DROP:
DEPTH TO WATER:
LOG OF TEST PIT NO. T-1
DEPTH
SAMPLE DESCRIPTION OF MATERIAL
FIELD
PROJECT NO. LP17122
30 5
10 15
20 25
LABORATORY
DRYDENSITY (pcf) MOISTURE CONTENT (% dry wt.)
OTHER TESTS
BLOW COUNT
SHEET 1 OF 1
5/14/17
J. Lorenzana
Approximately 370’
N/A
N/A
N/ABackhoe
N/A
15 Feet
PLATE B-6
USCS CLASS. POCKET PEN. (tsf)
SAND (SP-SM): Grayish brown, dry, fine grained
increase in silt content
104.4 1.8
Total Depth = 15.0’
Moisture and density values by Nuclear Densometer (ASTM 6938) Backfilled with excavated soil
DATE EXCAVATED:
LOGGED BY:
TOTAL DEPTH:
SURFACE ELEVATION:
TYPE OF BIT: DIAMETER:
HAMMER WT.: DROP:
DEPTH TO WATER:
LOG OF TEST PIT NO. T-2
DEPTH
SAMPLE DESCRIPTION OF MATERIAL
FIELD
PROJECT NO. LP17122
30 5
10 15
20 25
LABORATORY
DRYDENSITY (pcf) MOISTURECONTENT (% dry wt.)
OTHER TESTS
BLOW COUNT
SHEET 1 OF 1
5/14/17
J. Lorenzana
Approximately 370’
N/A
N/A
N/ABackhoe
N/A
15 Feet
PLATE B-7
USCSCLASS. POCKETPEN. (tsf)
SAND (SP-SM): Grayish brown, dry, fine grained
increase in silt content
105.4
104.0
2.5 2.8
Total Depth = 15.0’
Moisture and density values by Nuclear Densometer (ASTM 6938) Backfilled with excavated soil
DATE EXCAVATED:
LOGGED BY:
TOTAL DEPTH:
SURFACE ELEVATION:
TYPE OF BIT: DIAMETER:
HAMMER WT.: DROP:
DEPTH TO WATER:
LOG OF TEST PIT NO. T-3
DEPTH
SAMPLE DESCRIPTION OF MATERIAL
FIELD
PROJECT NO. LP17122
30 5
10 15
20 25
LABORATORY
DRYDENSITY (pcf) MOISTURECONTENT (% dry wt.)
OTHER TESTS
BLOW COUNT
SHEET 1 OF 1
5/14/17
J. Lorenzana
Approximately 370’
N/A
N/A
N/ABackhoe
N/A
15 Feet
PLATE B-8
USCSCLASS. POCKETPEN. (tsf)
SAND (SP-SM): Grayish brown, dry, fine grained
increase in silt content
105.3
105.1
2.3 3.0
Total Depth = 15.0’
Moisture and density values by Nuclear Densometer (ASTM 6938) Backfilled with excavated soil
DATE EXCAVATED:
LOGGED BY:
TOTAL DEPTH:
SURFACE ELEVATION:
TYPE OF BIT: DIAMETER:
HAMMER WT.: DROP:
DEPTH TO WATER:
LOG OF TEST PIT NO. T-4
DEPTH
SAMPLE DESCRIPTION OF MATERIAL
FIELD
PROJECT NO. LP17122
30 5
10 15
20 25
LABORATORY
DRYDENSITY (pcf) MOISTURECONTENT (% dry wt.)
OTHER TESTS
BLOW COUNT
SHEET 1 OF 1
5/14/17
J. Lorenzana
Approximately 370’
N/A
N/A
N/ABackhoe
N/A
15 Feet
PLATE B-9
USCSCLASS. POCKETPEN. (tsf)
SAND (SP-SM): Grayish brown, dry, fine grained
increase in silt content
98.9 100.0
2.0 2.6
Total Depth = 15.0’
Moisture and density values by Nuclear Densometer (ASTM 6938) Backfilled with excavated soil
DATE EXCAVATED:
LOGGED BY:
TOTAL DEPTH:
SURFACE ELEVATION:
TYPE OF BIT: DIAMETER:
HAMMER WT.: DROP:
DEPTH TO WATER:
LOG OF TEST PIT NO. T-5
DEPTH
SAMPLE DESCRIPTION OF MATERIAL
FIELD
PROJECT NO. LP17122
30 5
10 15
20 25
LABORATORY
DRYDENSITY (pcf) MOISTURECONTENT (% dry wt.)
OTHER TESTS
BLOW COUNT
SHEET 1 OF 1
5/14/17
J. Lorenzana
Approximately 370’
N/A
N/A
N/ABackhoe
N/A
15 Feet
PLATE B-10
USCSCLASS. POCKETPEN. (tsf)
SAND (SP-SM): Grayish brown, dry, fine grained
increase in silt content
109.0
103.0
1.6 2.3
Total Depth = 15.0’
Moisture and density values by Nuclear Densometer (ASTM 6938) Backfilled with excavated soil
DATE EXCAVATED:
LOGGED BY:
TOTAL DEPTH:
SURFACE ELEVATION:
TYPE OF BIT: DIAMETER:
HAMMER WT.: DROP:
DEPTH TO WATER:
LOG OF TEST PIT NO. T-6
DEPTH
SAMPLE DESCRIPTION OF MATERIAL
FIELD
PROJECT NO. LP17122
30 5
10 15
20 25
LABORATORY
DRYDENSITY (pcf) MOISTURECONTENT (% dry wt.)
OTHER TESTS
BLOW COUNT
SHEET 1 OF 1
5/14/17
J. Lorenzana
Approximately 370’
N/A
N/A
N/ABackhoe
N/A
15 Feet
PLATE B-11
USCSCLASS. POCKETPEN. (tsf)
SAND (SP-SM): Grayish brown, dry, fine grained
increase in silt content
104.0
105.9
1.8 1.9
Total Depth = 15.0’
Moisture and density values by Nuclear Densometer (ASTM 6938) Backfilled with excavated soil
DEFINITION OF TERMS
PRIMARY DIVISIONS SYMBOLS SECONDARY DIVISIONS
Gravels GW
GP
GM
GC
Sands SW
SP
SM
SC
Silts and clays ML
CL
OL
Silts and clays MH
CH
OH
Highly organic soils PT
Fine Medium Coarse Fine Coarse US Standard Series Sieve Clear Square Openings
Clays & Plastic Silts Strength ** Blows/ft. *
Sands, Gravels, etc. Blows/ft. * Very Soft 0-0.25 0-2
Very Loose 0-4 Soft 0.25-0.5 2-4
Loose 4-10 Firm 0.5-1.0 4-8
Medium Dense 10-30 Stiff 1.0-2.0 8-16
Dense 30-50 Very Stiff 2.0-4.0 16-32
Very Dense Over 50 Hard Over 4.0 Over 32
* Number of blows of 140 lb. hammer falling 30 inches to drive a 2 inch O.D. (1 3/8 in. I.D.) split spoon (ASTM D1586). ** Unconfined compressive strength in tons/s.f. as determined by laboratory testing or approximated by the Standard Penetration Test (ASTM D1586), Pocket Penetrometer, Torvane, or visual observation.
Type of Samples:
Ring Sample Standard Penetration Test Shelby Tube Bulk (Bag) Sample Drilling Notes:
1. Sampling and Blow Counts
Ring Sampler - Number of blows per foot of a 140 lb. hammer falling 30 inches.
Standard Penetration Test - Number of blows per foot.
Shelby Tube - Three (3) inch nominal diameter tube hydraulically pushed.
2. P. P. = Pocket Penetrometer (tons/s.f.).
3. NR = No recovery.
4. GWT = Ground Water Table observed @ specified time.
Project No. LP17122
Silty sands, sand-silt mixtures, non-plastic fines
Clayey sands, sand-clay mixtures, plastic fines
More than half of
coarse fraction is
larger than No. 4
sieve
Inorganic clays of high plasticity, fat clays
Organic clays of medium to high plasticity, organic silts Poorly graded sands or gravelly sands, little or no fines Peat and other highly organic soils
Inorganic silts, clayey silts with slight plasticity
Inorganic clays of low to medium plasticity, gravely, sandy, or lean clays Organic silts and organic clays of low plasticity
Inorganic silts, micaceous or diatomaceous silty soils, elast ic silts Coarse grained soils More
than half of material is larger
that No. 200 sieve
More than half of
coarse fraction is
smaller than No. 4
sieve
Silts and Clays
Clean gravels (less
than 5% fines)
Gravel with fines
Clean sands (less
than 5% fines)
Sands with fines
Fine grained soils More than
half of material is smaller
than No. 200 sieve
Liquid limit is more than 50%
Liquid limit is less than 50%
GRAIN SIZES
Well graded gravels, gravel-sand mixtures, little or no fines Poorly graded gravels, or gravel-sand mixtures, little or no fines Silty gravels, gravel-sand-silt mixtures, non-plastic fines Clayey gravels, gravel-sand-clay mixtures, plastic fines Well graded sands, gravelly sands, little or no fines
Plate
B-12Key to Logs
Sand Gravel
Cobbles Boulders
200 40 10 4 3/4" 3" 1 2"
APPENDIX C
Project No.:
SIEVE ANALYSIS
LP17122 Grain Size Analysis
FineCoarse MediumFineCoarse
Plate
C-1
Cobbles and Boulders Gravel Sand Silt and Clay
0 10
20 30
40 50
60 70
80 90
100
0.0010.010.1110100
Percent Passing by Weight
Particle Size (mm)
B-1 @ 0-3 ft.
LMAND ARK
Ge o-En ginee rs and Geologist s
0 10
20 30
40 50
60 70
80 90
0.0100.1001.00010.000100.0001000.000
Percent Passing by Weight
Particle Size (mm)
B-1 @ 0-3 ft.
Project No.:
SIEVE ANALYSIS
LP17122 Grain Size Analysis
FineCoarse MediumFineCoarse
Plate
C-2
Cobbles and Boulders Gravel Sand Silt and Clay
0 10
20 30
40 50
60 70
80 90
100
0.0010.010.1110100
Percent Passing by Weight
Particle Size (mm)
B-1 @ 23 ft.
LMAND ARK
Ge o-En ginee rs and Geologist s
0 10
20 30
40 50
60 70
80 90
0.0100.1001.00010.000100.0001000.000
Percent Passing by Weight
Particle Size (mm)
B-1 @ 23 ft.
Project No.:
Plate
C-3
Cobbles and Boulders Gravel Sand Silt and Clay
SIEVE ANALYSIS
LP17122 Grain Size Analysis
FineCoarse MediumFineCoarse
0 10
20 30
40 50
60 70
80 90
100
0.0010.010.1110100
Percent Passing by Weight
Particle Size (mm)
T-2 @ 0-3 ft.
LMAND ARK
Ge o-En ginee rs and Geologist s
0 10
20 30
40 50
60 70
80 90
0.0100.1001.00010.000100.0001000.000
Percent Passing by Weight
Particle Size (mm)
T-2 @ 0-3 ft.
Project No.:
Plate
C-4
Cobbles and Boulders Gravel Sand Silt and Clay
SIEVE ANALYSIS
LP17122 Grain Size Analysis
FineCoarse MediumFineCoarse
0 10
20 30
40 50
60 70
80 90
100
0.0010.010.1110100
Percent Passing by Weight
Particle Size (mm)
T-4 @ 0-3 ft.
LMAND ARK
Ge o-En ginee rs and Geologist s
0 10
20 30
40 50
60 70
80 90
0.0100.1001.00010.000100.0001000.000
Percent Passing by Weight
Particle Size (mm)
T-4 @ 0-3 ft.
CLIENT:
PROJECT:
JOB No.:
DATE:
Boring: B-1 Caltrans
Sample Depth, ft: 0-3 Method
pH: 8.7 643
Electrical Conductivity (mmhos): -- 424
Resistivity (ohm-cm): 11,000 643
Chloride (Cl), ppm: 40 422
Sulfate (SO4), ppm: 0 417
Material Chemical Range Degree of
Affected Agent of Values Corrosivity
Concrete Soluble 0 - 1,000 Low
Sulfates 1,000 - 2,000 Moderate
(ppm) 2,000 - 20,000 Severe
> 20,000 Very Severe
Normal Soluble 0 - 200 Low
Grade Chlorides 200 - 700 Moderate
Steel (ppm) 700 - 1,500 Severe
> 1,500 Very Severe
Normal Resistivity 1 - 1,000 Very Severe
Grade (ohm-cm) 1,000 - 2,000 Severe
Steel 2,000 - 10,000 Moderate
> 10,000 Low
Project No.: LP17122
General Guidelines for Soil Corrosivity
Selected Chemical
Test Results C-5
Plate
LANDMARK CONSULTANTS, INC.
CHEMICAL ANALYSIS
Desert Care LLC
Living Care Assisted Living
LP17122
10/09/17
Client: Soil Description:
Project: Sample Location:
Project No.: Test Method:
Date: Maximum Dry Density (pcf):
Lab. No.: Optimum Moisture Content (%):
Plate
C-6Project No.: LP17122
Moisture Density Relationship
N/A
Gray Find Sand
B-1 @ 0-3'
ASTM D-1557 A
113.0
Desert Care LLC
LP17122
9/5/2017
7.2 Living Care Assisted Living
100
110
120
130
140
0 5 10 15 20 25 30
Dry Density (pcf)
Moisture Content (%)
Curves of 100%
saturation for
specific gravity
equal to:
2.75 2.70
2.65 APPENDIX D
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