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Andalusia TR 31681 BTCP2017-0003 (Plans 21-26) 2016 Code Update - Geotechnical Engineering Report UpdateT D-Desert Development, LP * 817570 Carboneras; La Quinta, California 92253 000,;7=0 ` F . CCTV OF L:XQUINTA • r �. ;BUILDING & SAFETY DEPT[ , j APPROVED• p FOR CONSTRUCTION r DATE? S BY Geotechnical Engineering Report Update (Revised) - for : .a ; * . Andalusia @ Coral Mountain (Tract.Map 31681) t` • Lots: 98, 99, 100, 101, 102, 175, 180, and,187 ? `' r La Quinta, Riverside County, California .F May 30, 20171` « ` .''REC�IVYP s - JUN 0 8 2011 . CI`IY.bi- LA C UINTA - COMMUNITY DEVELOP MENT ' .'r r Sods rt w�Di bRIVEU, . S 1017 4 • , r C17Y OF (tea QU1 dTA f` x r _ C01%1MUNI7Y. DEVELOPMEN © 2017 Earth Systems Southwest f , j+•{ w t, Unauthorized use or copying of this document is strictly f .. py g y prohibited . ' without the express written consent of Earth Systems Southwest. . File No.: 09305-31' Doc: No.: 17-05-708R , ' Earth Systems Southwest 79-811B Country Club Drive TIMAR Bermuda Dunes, CA 92203-1244 Ph:760-345-1588 Fax:760-345-7315 www.earthsystemsxom May 30, 2017 File No.: 09305-31 Doc. No.: 17-05-708R T D Desert Development, LP 81-570 Carboneras ti La Quinta, California 92253 Attention: Mr. Nolan Sparks Subject: Geotechnical Engineering Report Update (Revised) Projects: Andalusia @ Coral Mountain (Tract Map 31681) Lots: 98, 99, 100, 101, 102, 175, 180, and 187 La Quinta, Riverside County, California Earth.Systems Southwest (Earth Systems) presents this geotechnical report update prepared for eight residential lots at the Andalusia project located at the southwest corner of Madison Street and Avenue 58 in La Quinta, Riverside County, California: This report presents our findings and recommendations for updating the project geotechnical report (Earth Systems, 2003). Earth Systems has revised a previous report (Doc. No. 17-05-708). This report includes two revisions_ from the previous report: 1. Lot 181 was incorrectly stated as a lot that was evaluated: This is a typographic error and should be omitted and replaced with Lot 180, which was evaluated. Lot 180 is correctly stated in this new report. 2. The depth dr stated on page 22 should be determined by the structural design engineer. This report partially completes our scope of services in accordance with our agreement Work Order, SWO-17-117, dated February 23, 2017. Due to a rush timeframe and need to have various lots updated immediately, this update was prepared. An update for the remaining lots will be prepared under separate cover. Other services that may be required, such as, but not limited to: precise grading and structural plan review, grading observation, footing observations and.de.nsity testing, are additional services and will be billed per our Fee. Schedule in effect at the time services are provided. Unless requested in writing, the client is responsible for distributing this report to the appropriate governing agency or other members of the design team. Mary 30, 2017 2 File No.: 09305-31 Doc. No.: 17-05-708R We appreciate the opportunity to provide our professional services. Please contact our office if there are any questions or comments concerning this report or its recommendations. 'Respectfully submitted, EARTH SYSTEMS SOUTHWFSTScop s. J\ No.6Q302 Anthony Cola rossi' 30 l$: Project Engineer PE 60302 G ER-Update/tc/klp/mr Distribution: 4/copies to T D.Desert Development, LP E-mail/Mr. Nolan Sparks: NSparks@rancholaguinta.com E-mail/Mr. Chris King: kingchris1962@yahoo.c6m EARTH SYSTEMS SOUTHWEST r I TABLE OF CONTENTS Page Section 1 INTRODUCTION 1 1.1 Project Description................................................................................................. 1 1.2 Site Description and Previous Grading Discussion ................................................. 2 1.3 Purpose and Scope of Services ..................... :...... ................................................... 3 Section 2 METHODS OF EXPLORATION AND TESTING 5 2.1 Field Exploration..................................................................................................... 5 Section 3 DISCUSSION 6 3.1 Soil Conditions ........................... :............................................................................. 6 3.2 Groundwater...........................................................................................................7 3.3 Collapse Potential .................................................... .................. .......... ...... ........... 11 3.4 Expansive Soils...................................................................................................... 11 3.5 Corrosivity.........................................................:...................................................11 3.6 Geologic Hazards.................................................................................................. 11 3.6.1 Soil Liquefaction and Lateral Spreading.......................................................... 11 3.6.2 Lateral Spreading............................................................................................ 14 3.6.3 Review of Current Subsidence Information.................................................... 15 3.6.4 Site Reconnaissance for Subsidence Related Distress .................................... 16 3.7 Flooding.................................................................................................................17 Section 4 CONCLUSIONS AND GENERAL RECOMMENDATIONS 19 Section 5 RECOMMENDATIONS 21 5.1 Site Development —Grading .................................................................................. 21 5.2 Excavations and Utility Trenches...........................:..............................................23 5.3 Slope Stability of Graded Slopes........................................................................... 23 5.4 Stiffened Foundations and Stiffened Slabs ................................... 5.4.1 Estimated Settlements for Shallow Foundations ....:...................................... 27 5.5 Slabs-on-Grade......................................................................................................28 5.6 Retaining Walls..................................................................................................... 29 5.7 Mitigation of Soil Corrosivity'on Concrete............................................................ 31 5.8 Seismic Design Criteria..................:....................................................................... 31 5.9 Site Drainage and Maintenance............................................................................ 32 Section 6 LIMITATIONS AND ADDITIONAL SERVICES 34 6.1 Uniformity of Conditions and Limitations............................................................ 34 6.2 Additional Services................................................................................................ 35 REFERENCES............................................................................................................... 37 EARTH SYSTEMS SOUTHWEST 1 Table of Contents, continued ii - APPENDIX A Plate 1—Site Vicinity Map Plate 2 — CPT Location Map Terms and Symbols Used on Boring Logs Soil Classification System Log of CPT-4 (2003) Logs of CPTs 7, 8,'and 9 (2017) Site Class Estimator B-1 Liquefaction CPT-4 (2003) Liquefaction CPT-7 (2017) Liquefaction CPT-8 (2017) F Liquefaction CPT-9 (2017) 4 • May 30, 2017 ' 1 File No.: 09305-31 Doc. No.: 17-05-708R -Geotechnical Engineering Report Update (Revision) • for Andalusia @ Coral Mountain (Tract Map 31681) t f Lots: 98, 99, 100, 101; 102, 175, 180, and 187. La Quinta, Riverside County, California' Section,1 r INTRODUCTION 1.1 Project Description , This update report has been prepared for eight lots for Tract Map 31681 in La Quinta, California. A client provided, document provides the entire tract showing existing lots with structures and remaining vacant lots (in yellow). This geotechnical report update covers -a portion of the vacant ` lots identified within the,figure below. This geotechnical report update covers the specific lots identified below, lots 98, 99, 100, 101, 102, 175, 180, and 187: jF AVENUES! n—moo �• ! 4^�� a � -�.i4. 98:99 100;`IOt;an0102,�7{2017) •� Lot 17 ra uaT-s , 7l, ./ � a`u�1 .�f•� � i-- ��` ) Y �� ot'18TanCCPTa't2003) ai , � '" 1j' ANDALUSIA _ TRACT 31681 - - Figure 1 Lots Specific Location Map. EARTH SYSTEMS SOUTHWEST May 30, 2017 2 File No.: 09305-31 Doc. No.: 17-05-708R 1.2 Site Description and Previous Grading Discussion The residential lots, which are part of this update, are currently vacant lots that were previously. mass graded in 2004 through 2005 and documented in a report of intermittent testing and observations (Earth Systems, 2006). That report indicates the site grading operations have met the intent of the recommendations for the referenced geotechnical report (Earth Systems, 2003). The report provides a figure showing the mass graded area, see Figure 2. Comparing this report's Figures 1 and 2, they appear similar. According to interviews with the client, grading has been completed on all lot pads; however, there may be a few pads that will need regrading because they are going through lot size changes, building plan changes, or pad elevation has changed. Earth Systems request to be notified if changes from the 2006 report to present have or will occur. Lots tested and observed in the 2006 report are underlain with an approximate minimum of five feet of engineered fill. It should be noted that the project geotechnical report (Section 5.1) has two requirements for over -excavation: one was to over -excavate to 4 feet and the second was to over -excavate to 3 feet below the bottom of footings. Therefore, any building footings having embedment depths greater than 12 inches, should be reviewed by Earth Systems for adequate over -excavation requirements. Mass and Rough grading plans produced by Watson & Watson and obtained from the City of La Quinta Engineering Archive database (City of La Quinta, PSN 04001 and PSN 06208) where used to estimate original and current ground surface elevations. Since the true surface elevations are below sea level, the civil engineer indicates on City PSN 06208 (Sheet 1 of 20) and other plans, "Subtract 500 feet from elevation shown to obtain mean sea level". For clarity in this report, Earth Systems converted back to mean sea level elevations to compare well data and other researched data, which uses mean sea level elevations. In Figure 2 Mass Grading Area addition to using project approved plans, project elevations were also verified using a 2001 USGS topographic map having a USGS map name of "La Quinta" and reference code of "33116-F3-TF-024", see Figure 3. Note, this map was produced prior to grading disturbance. EARTH SYSTEMS SOUTHWEST May 30, 2017 3 File No.: 09305-31 Doc. No.: 17-05-708R Y UE '� SA AVENUE 28 27 •9«i" 26 � r^� sfs rt�ss way : • - de Andalusia @ Coral Mountain aw.sYcaa•a � � ) M 4 W� C4'3U pYNG�➢. 3 �50.e ��, s-.A��w.f�r 5 �� -�aYL, <,c..- -. _ _ —� _�� t�k� �� _ _��..PIP$GINE2 �j, •�,_ yy xsoYN. � �1JL• 1 Ay Yuk iL�Y � ouC1LI� ^•' av rgPtr,� a (" ] f1M •u (.f •Qiii333 w .• O it i«c ♦ Wr�i.b V\AWE ! tY�4i"�Y• Ym Y♦ it y JY. dJ. 4 Y(I �♦♦♦+ ♦♦♦♦ a • -@ �.+vie ��•a Y♦ .ace . - ;.,,F 76 _AVENUE W Z _ y � \ Figure 3 2001 USGS Map Name La Quinta Zoom of Project 1.3 Purpose and Scope of Services The purpose for our services was to update the project geotechnical report (Earth Systems, 2003) to the 2016 California Building Code and the current standard of care. This involved six scopes of work: 1. Review of select project documents 2. Subsidence distress site evaluation 3. Site Reconnaissance and update of current groundwater elevation 4. Seismic (dry and liquefaction) settlement evaluation under the 2016 California Building Code accelerations using past borings and CPT sounding data and current groundwater level information. 5. Review of Past Reports 6. Update report for the noted lot areas. Note: Additional information gathered through the processes above, lead to additional in - situ field testing and lateral spreading study. Specifically, the scope of services included: 1. Surficial site conditions were visually assessed and selected published reports were reviewed for this site: Earth Systems, Coachella Valley Water District, City of La Quinta, Ludwig, and Watson & Watson. EARTH SYSTEMS SOUTHWEST May 30, 2017 4 File No.: 09305-31 Doc. No.: 17-05-708R 2. In. addition to the 2003 project geotechnical report, our field exploration included subsidence distress site evaluation and desktop study for current and future groundwater elevations. 3. Engineering analysis of the data generated from this study was performed and a written report prepared to present our findings and recommendations, which includes the following: • An updated description of the proposed project including a site plan showing the areas to be updated; • An updated description of the surface and subsurface site conditions including groundwater conditions, as determined in our research; • An updated discussion of other select geologic hazards (liquefaction and dry seismic); • An updated evaluation.of lateral spreading with estimated displacements; • A discussion of site conditions, including the geotechnical suitability of the site for the general type of construction proposed; • Updated geotechnical seismic design coefficients and extended soil profile to a depth of 50 feet bgs in accordance with the 2016 California Building Code; • Updated recommendations for foundation design including parameters for shallow foundations, and subgrade preparation; • Updated anticipated total and differential settlements for the preliminary foundation system; • Updated recommendations for lateral load resistance (earth pressures and drainage); • Updated discussion of anticipated excavation conditions; • Updated recommendations for stability of temporary trench excavations; • Updated recommendations for slabs -on -grade, including recommendations for reducing the potential for moisture transmission through interior slabs; EARTH SYSTEMS SOUTHWEST May 30, 2017 5 File No.: 09305-31 Doc. No.: 17-05-708R Section 2 METHODS OF EXPLORATION AND TESTING 2.1 Field Exploration For the remaining residential lots and for this report update that is a portion of the remaining residential lots, Earth Systems performed ten additional cone penetration test (CPT) explorations. The CPTs were performed on April 17, 2017 and April 20, 2017. This update report covers only lots 98, 99, 100, 101, 102, 175, 180, and 187, and four CPTs (CPT-4 (2003), CPT-7 (2017), CPT-8 (2017), and CPT-9 (2017) were used for liquefaction and lateral spreading analysis due to their close proximity to the stated lots. The CPT explorations were placed at vacant pad grades adjacent to existing lakes. The CPT soundings were advanced by Kehoe Testing & Engineering, Inc, based at Huntington Beach, California utilizing a 25 Ton CPT rig equipped with electronic measuring cone and sleeve. The CPT equipment consisted of a cone assembly mounted at the end of hollow sounding rods. A set of hydraulic rams was used to continuously push the cone and rods into the soil at a rate of approximately 1 to 4 feet per minute while the cone tip resistance and sleeve friction are recorded every 50-mm (2 inches) and stored in digital form. The 25-ton truck provided the required reaction weight for pushing the cone assembly and was also used to transport and house the test equipment. The cone penetrometer assembly consisted of a conical tip (60-degree angle, 35.6-mm dia.) and a cylindrical friction sleeve (133 mm in length, 35.8 mm diameter) instrumented on the interior, with strain gauges that allow simultaneous measurement of the resistance during penetration. CPT's were advanced to depths on the order of 50 feet below the existing ground surface and were backfilled once complete. EARTH SYSTEMS SOUTHWEST May 30, 2017 6 File No.: 09305-31 i Doc. No.: 17-05-708R Section 3 - DISCUSSION _ y 3.1 Soil Conditions , Three CPT sounding graphs indicated typical Ancient Lake Cahuilla lake and sand dune deposits of alternating layers of sand to'silty-sand (light yellow/orange) with silty sand to sandy silts (light , r; greenish) as shown in the figure below (yellow and greenish rectangles). Also, clay layers, which could ,play a significant role in the lateral spreading displacement. results, shown in darker blue are seen alternating with the sand layers mentionedIabove. These clay layers were typically found at depths greater than 20 feet below the ground surface (bgs). For these three digital soil profiles, at an elevation depth of 386 feet (-114 feet MSL), clean sand layers appear. Digital electronic soil i data from the 2017 CPT were correlated with "past laboratory data (Earth Systems, 2003, 2012 f • t ' `CPT=7(2017) CPT (20-1 JCPT=9,(2017) - •0 )5011 BehaviotirType , Sid.& silt' send +_ s _ Sand & sdy sand . Sand& silty sand ' Silly sand & sandy sin ' Is Sand & Silly- sand _ -- ^ Silty.sand&sandy.sill 20- 4 . Sam & sat�yy sar>d 2S Silly sand sandy. sill S and & sd sand Et' . S �ffW & silty satxi ± er4d n y sa4 sill SM 30- SGIy sand & sandy sill .-. 3s i a Sled & silty sand ' Silly sand & sandy Sill $ily-sand & sandy sill 40 CaLrj - Sand & sit send- CS 4S ' • sand Sandy sill S0._ Clay & silty clay Sdy sand & sa sill SMd&silly,sard�. ss .«..,....., ...� • S and + 60 4 Sand & silly Sand Silty sand'& sandy sell GS •t 70 •,r. i �75 Figure 4 CPT Graphs. EARTH SYSTEMS SOUTHWEST May 30, 2017 7 File No.: 09305-31 Doc. No.: 17-05-708R 3.2 Groundwater Past Reports Based on past geotechnical reports: (Buena Engineers, 1990) and (Earth Systems, 2012) of the subject project, free groundwater was encountered at 19 feet below the ground surface in 1990 and at 45 feet below the ground surface in 2012. Past reports indicate a historic groundwater at approximately 20 feet below the ground surface with the reports assuming a ground surface elevation of approximately -60 feet. From a historic groundwater contour map (see Figure 5) produced using spring of 1961 information (Department of Water Resources Bulletin 108, Plate 6 in that report), the historic groundwater contour nearest the project is -80 feet Mean Sea Level. Since the project site has an estimated surface elevation ranging between approximately -60 feet, the historic groundwater water surface elevation (WSE) is assumed at -80 feet msl, which agrees well with past reports. Previous Earth Systems reports (Earth Systems, 2012) indicate that "However it is our opinion that with so many demands on the regions water system, it is impossible to predict the magnitude of groundwater withdrawal or introduction and it may be prudent to reevaluate this issue periodically as newly publicized data becomes available on CVWD policies." It is also observed on the historic groundwater contour map, the Andalusia project and CVWD Well No.: 6728 (see "Nearby Well Information" Section in this report) is not within the Oasis Subarea where groundwater recharging ponds are located. r SEEN z� f'%% A A 1r% I A 1 -11 K I- r- -11^ ON Figure 5 1961 Contours of Ground Water Levels, (Department of Water Resources Bulletin 108) EARTH SYSTEMS SOUTHWEST May 30, 2017 8 File No.: 09305-31 Doc. No.: 17-05-708R Nearby Well Information The Coachella Valley Water District (CVWD) has two nearby wells that they monitor: CVWD Well No.: 6729 and Well No.: 6728, which have latitudes and longitudes of 33.60981N and 116.2338°W for Well No.: 6729 and 33.6097ON and 116.2503°W for 6728. A database of groundwater readings from the wells .were provided to Earth Systems via CVWD in an email (CVWD, 2017). The data ranges from the year 2006 to 2017. The graph shown in the figure below provides true Average Annual' Water Elevations from 2006 to 2016. For the well furthest downstream on the adjacent Trilogy subdivision (Well No.: 6728), Earth Systems used the last three years of data to provide a trendline that extends out to the year 2020. Earth Systems uses this trendline to estimate the year that the groundwater well reading statistically could be at - 70 foot elevation. Water -well -data information used to produce the graph reveals there is a progressively increasing WSE and no definitive understanding at this time of a tapering or decrease in WSE (see Figures 7 and 8, E-mails Coachella Valley Water District Groundwater Level Increases and Tile Drain Systems). The last three years shows the difference in water surface elevations between the upstream and downstreamwells is almost constant. This corresponds with f groundwater recharge occurring in the project area by CVWD. Trendline information was used to predict and gain information for liquefaction settlement, lateral spreading, groundwater seepage and other parts of this report: 1. Andalusia's historic -WSE of -80 feet (Earth Systems WSE used in past and present liquefaction settlement evaluations) could be reached in 2017 if the CVWD well water expands further.toward Andalusia project. 2. The WSE of -70 feet (Earth Systems WSE used for additional liquefaction settlement evaluation) will be reached in 2019 if the CVWD well water readings expand toward the Andalusia project.. 3. The wells WSE of -60 feet (Andalusia's historic mean ground surface elevation) will be reached in 2021. However, the low spot at Andalusia appears to be near the intersection of Avenue 60 and Monroe Avenue having a google image elevation of -77 feet. n EARTH SYSTEMS SOUTHWEST W. May 30, 2017 - .1 -u -16, M CVWD Well Monitoring Data yuf File No.: 09305-31 Doc. No.: 17-05-708R rlgure b Approximate Vrounawater Location Kelative to the Project Research of Coachella Vallev Water. District Groundwater Level Increases and Tile Drain Svstem Throughout the production of this update report, Earth Systems made contact with CVWD representatives after reviewing the monitoring well data. Earth Systems requested information from CVWD in an email dated March 8 and 10, 2017. From those emails, see figures below, Earth Systems' current understanding of groundwater level rise control is that the only control to prevent groundwater level increases is from the existing tile drain system. This tile drain system was typically installed in the 1950s and '60s to control water for agricultural purposes. EARTH SYSTEMS SOUTHWEST May 30, 2017 10 ' File No.: 09305-31 Doc. No.: 17-05-708R From: Saul Montalvo`[mailtfisSMofitalyc@Widiorgl, sent: Thursday; March 09; 2017 4:13 PM ' To: TonyColarossi.<tcatarossl(aeartfisystericscomi Cc: Ivory Reyburn 5iReyburnO&wdiVr Subject: Well Readings at Andalusia Tony, The goal of the Coachella Valley Water Management. Plan is to eliminate overdraft of the groundwater basin. Part of accomplishing this goal is to return groundwater levels to historic levels: Already; we are seeing many wells in the east valley that historically had artesian pressure returning to artesian conditions. That, means groundwater levels In some areas of the eastmalley could fl:tum to around 50 feet above the ground surface. Until then; we still have work to do. So to.answer your question, aside from controlling the mounding beneatha, replenishment facility, currently the goal is to increase groundwaterleiiels., Please let us know if you have any further questions Thank you a From: Tony Colaros';i.[Mallt6:ttdlaroselo6artfisys_tems.coml, Sent:' Wednesday, March 08,.2617 3:15 PM To: Saul'Montalvo Subject: RE: Well Readings at Andalusia Good Afternoon,-mi. Montalvo: Thanks for the well monitoring data you provided last Friday. In reviewing the two monitoring well data sheets you provided, I can see the "Average Annual Water Surface Elevation' continues to rise, see example for the most westerly well data in the figure below. Can I ask, are there procedures to limit how high the water surface elevation can rise in the monitoring well ? I ask because rm updating a geotechnical report for Andalusia and a liquefaction evaluation will be performed. To do this, I need a historic groundwater elevation, which has been stated in the past as 20 feet below the ground surface (ground surface varied from approximately -45 to -70). So, your well is already showing a water surface elevation of -77.9 and my historic is between -65 to -90, either the historic water level has been exceeded or a gradient exists, which the latter Is probably the case. However, we have no way of telling unless we get some type of monitoring well at Andalusia. So that's my problem. Back to my question, are there groundwater recharging procedures that limit how high the water surface elevation can rise In the monitoring wells ? Figure 7 E-mail on Groundwater Rise Limiting Procedures P.'Reyy P_ReplyAll RFe d IvoryReyoum slReyburn@cvwfl.orgs rmycolwaa:saulm n" - RE: Well Readings at Andalusia e You faiw.rdcd this mesuge an3/10(M73.18 PM. _ WniffAw HI Tony, Fn 3da fl + more sdd•n No, to my knowledge the Coachella Valley water Management Plan does not say It -will not allow groundwater levels to r e more than 30 feet belmv.the ground surface. uqueraction was a pe•existfng condition in the east valley. The subsurface vie drain system was installed to collect." groundwater and drain It to the stoim channel%Salton sea. - tv" From: Tony Colaloiil[irtaiR.i:[caFarassieoSrttiivitL+m�minl writ Friday, Mardi 10, 2017 2:27 PM To: Saul Montatvp r CC ivory Rayburn subject RE: "W Readings at Andalusia Thanks Saul and Ivory for the Information: 1 was hoping you were going to say that CVWI) will not allow historic groundwater levels to Ilse but 1 didn't get that comfortable feeling that was the core, well for now. . A colleague of.inine from Earth Systems says that.CVW0 has published in Its Draft 2010 Groundwater Management Plan that cVwO "will not allow groundwater levels to else more than 30 feet below the ground surface:' Can you tell me lh thou }true and ti It's tNo nov(f Figure 8 Email from CVWD Regarding Liquefaction and Tile Drains. EARTH SYSTEMS SOUTHWEST May 30, 2017 111 File No.: 09305-31 Doc. No.: 17-05-708R From this information and at this time, Earth Systems assumes the tile drainage system works and the groundwater level rise is controlled by the depth of the tile drainage system, which is assumed at this time is ten feet below the ground surface when the tile drain was placed. For this update report and understanding the depth to groundwater based on tile drainage is unpredictable knowing historic levels in the wells have been exceeded, Earth System will assume a groundwater elevation of 10 feet below the historic ground surface, which is -70 feet. 3.3 Collapse Potential The. project site is -in a geologic environment where the potential for collapsible soil can exist. The results of original project soils report for collapse potential tests indicated a range of collapse potential on, the order of 0 to 1.7 percent at an applied vertical stress of 2,000 psf. The average collapse potential for five test results is 0.7 %. It was our opinion that the site soils have a low potential for collapse. In addition, the 2012 update report for the Racquet Club Facilities and Residential Improvements (Earth Systems, 2012) tests, indicated collapse potential generally less than 1.1 percent. It was also the opinion in the 2012 report that the site soils have a low potential for collapse., Collapse related settlement is estimated to be low. 3.4 Expansive Soils t Expansion Index of the onsite soils is anticipated to be "very low" to "low" as defined by ASTM D 4829. Samples of building pad soils should be observed or tested prior to footing excavation to confirm or modify these findings. 3.5 Corrosivity Although Earth Systems does not practice corrosion engineering, the corrosion values from the original project soils report (Earth Systems, 2003) soil tested are normally considered as being "Severe Corrosive" to "Very Severe Corrosive" to buried metals and as possessing a "Severe" exposure to sulfate attack for concrete as defined in American Concrete Institute (ACI) 318, Section 4.3. The above designations can potentially change based on several factors, such as importing soil from another job site and the quality of construction water used during grading and subsequent landscape irrigation. 3.6 Geologic Hazards 3.6.1 Soil Liquefaction and Lateral Spreading Liquefaction is the loss of soil strength from sudden shock (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 EARTH SYSTEMS SOUTHWEST May 30, 2017 12 File No.: 09305-31 Doc. No.: 17-05-708R soils and low plasticity clay and silt. These soil types exist throughout the site area. The site is within a "high" liquefaction potential zone as identified by Riverside County (Riverside County Transportation and Land Management Agency land information website (RCLIS, August, 2013)). 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. Historic groundwater conditions are shallow in the site area at an approximate WSE -80 feet with a potential to rise even higher. In the past decade, several concentrated efforts have been made to come up with a uniform guideline for liquefaction analyses. Youd et al. (2001) published general guidelines for 4 liquefaction analyses, which presented consensus of a task committee comprised of more than 20 members from all over the United States'., However, earthquakes in Turkey and Taiwan provided additional data to researchers, especially for low plasticity clays and silts, which resulted in significant modifications to liquefaction evaluation methods for these soils with higher fines contents whereby they may behave in a "sand like" liquefiable manner during a seismic event under certain circumstances related to the Plasticity Index (PI), Liquidity Index (LI) and sensitivity. If those circumstances are not met, the soils can be thought of as performing in a "clay like" manner and not be liquefiable. Some of these methods have been presented by Boulanger and Idriss (2006). For fine grained soils, our liquefaction analysis considered the approaches recommended by Boulanger and Idriss (2006) for evaluating whether onsite fine-grained soils may behave in a "sand like" or "clay like" manner and Youd et al. (2001) for coarse grained soils. Based on the soil conditions observed and anticipated seismic shaking, we believe that the potential for liquefaction of certain fine grained soils may exist. As presented by Boulanger and Idriss (2006), for practical purposes, fine grained soils can confidently be expected to exhibit clay -like behavior if they have PI >_7. This criterion provides a slightly conservative interpretation of the likely transition interval and includes all CL soils by definition. If soil plots as a CL-ML, the PI criterion may be reduced to PI >_5 and still be consistent with the available data. Fine grained soils that do not meet the above criteria'should be considered as likely exhibiting sand -like behavior (i.e. liquefiable), unless shown otherwise through detailed in situ and laboratory testing. As presented in previous lab testing the soils identified as sandy silt/silty sand are potentially liquefiable, while soils identified as clay had Pis higher than seven (7) are considered not liquefiable. For coarse grained soils, we have used the data obtained from our deep borings at the site to evaluate the potential for liquefaction induced settlement. We estimated seismically in settlements in general accordance with methods developed by Tokimatsu and Seed (1987), the 1996 NCEER and 1998 NCEER/NSF workshops on liquefaction,. and considered information provided in Recommended Procedures for Implementation of DMG Special Publication 117, Guidelines for Analyzing and Mitigating Liquefaction Hazards in California, published by Southern California Earthquake Center (SCEC), dated March 1999 and Guidelines for Analyzing and Mitigating Seismic Hazards in California, Special Publication 117A, published by California Geological Society (CGS), 2008. Our analysis incorporated multi -directional shaking and used a Design Earthquake ground motion of 0.54 g associated with a magnitude 8.2 earthquake associated with a multi -segment rupture of the San Andreas fault. We used a groundwater depth EARTH SYSTEMS SOUTHWEST May 30, 2017 13 File No.: 09305-31 Doc. No.: 17-05-708R ' of 20 feet (-80 MSL) for historic analysis and 10 feet (-70 feet MSL) for possible future evaluations ' based on the information provided in the groundwater section of this report. A factor of safety against liquefaction of 1.5 was used for evaluation. t For these eight lots, Earth Systems'used one past CPT exploration and three CPT soundings' gr explored on April 17, 2017 to evaluate the seismic settlements at the project site. For seismic , displacements calculated for slopes and free faces, the spectral acceleration (Sa) was determined from the Maximum Considered Earthquake (MCE) having a 2% in 50 years return period. The' ' r. selected soundings (Cone Penetrometer Test (CPT)) used are as following: 1. CPT-4 (Earth Systems, 2003) 2. CPT-7 (2017) t 3. CPT-8 (2017) i 4. CPT-9 (2017) Two CPT soundings were found near lots 98, 99, 100; 101, and 102, which are CPT-21 (Earth Systems, 2005, Addendum to Geotechnical'Engineering Report) Iand CPT-7 (2017).'After review -of the soil profiles and engineering properties, we determined CPT-7 was more -susceptible to liquefaction and lateral spreading'. CPT-7 (2017) was used for lots 98, 99, 100, 101, and 102.. The results of our analyses (using the historic groundwater surface elevation (-80 MSL) indicate that zones of soil liquefaction will occur within the observed sandy soils at various depths. Total' estimated liquefaction -induced and dry seismic settlement of t4 total soil columns (upper 50 t feet) is on the order, of 1.3 to 5.3 inches with the groundwater at -80 feet MSL. Additionally, it is our opinion that the potential for sand boil formation to relieve subsurface pore -water pressures = generated during a seismic event is probable for'soundings CPT-4 (2003) and CPT-9 (2017). Tanks or buoyant structures founded below grade may be subject to hydrostatic forces during a seismic .event due to hydrostatic pressure and becomes even more likely as the groundwater rises higher. The recommended remedial grading presented in subsequent sections of this report has been, 1 provided to reduce potential for structure distress should liquefaction of these soils occur. Table'1 Liquefaction and. Dry Seismic Settlement Magnitude 8.2 and PGAM of 0.54 e' . f r Ir Lp ,PadElev Liquefacton" `.Liq r''� uefaction Explorations Exploration `'Lowest . , + DrySeismic . . 4 Dry Seismic= x t_ Designation j Date ` Structure,'. GW_E 80, GWE= 70 ~T F YY °.s . (MSL)2 ^' r • '•�.�in)t " t `< (in) . C CPT-4 2003 -68 1.3 f 1.5 CPT-7 2017 -57 ' 3.3 3.1 - CPT-8 2017 -67 4.0 , 3.7 CPT-9 ' 2017 -67 5.3 5.0 i EARTH SYSTEMS SOUTHWEST i May 30, 2017 14 File No.: 09305-31 Doc. No.: 17-05-708R The results of our analyses (using a ten -foot rise above the historic groundwater surface elevation (-70 MSL) indicate that zones of soil liquefaction will occur within the observed sandy soils at various depths. Typically, an increase of groundwater indicates higher settlement, but this is not always the case because of the effective overburden stresses and very shallow groundwater, as seen by the Table 1 results. The total seismically induced settlement is exclusive and independent of any static settlement that may occur from foundation loads. The potential for total and differential settlements is addressed in a section of this report (see Section 5.4). Typically, structural mitigation is acceptable when total settlements are small. Per SP117A (2008, page 54), citing data from Japan, suggests that structural mitigation may be acceptable where displacements are not large scale. For SP117A, large-scale ground displacements are defined as those that exceed 1-3 feet horizontally and 4-6 inches vertically. 3.6.2 Lateral Spreading Lateral spreading may also be defined as the stability of a slope during and just after a seismic event has ended. Lateral spread analysis involves a screening analysis and if the screening analysis shows large displacements (greater than 0.5 meter) then a more -comprehensive quantitative evaluation needs to be conducted. The screening analysis was performed using methods from Faris (2006) and Zhang et al (2004). Screening results indicated potential displacements ranging between 1.1 to 8.9 feet, which indicates potential for liquefaction induced lateral spreading could be considered high for structures near the lakes and more detailed evaluation should be performed. From.California Geologic Survey (CGS) SP 117a (2008) section for Mitigation of Liquefaction Hazards, "large scale ground displacements are defined as those that exceed 1-3 feet horizontally...". Therefore, Earth Systems in conjunction with TD Development (meeting with Nolan Sparks, Wednesday, May 10, 2017 at noon) selected 1 foot as the benchmark to do no further study of ground improvements or to continue to study ground improvements. As shown in the third column of Table 2, values of H'max exceeding 1.6 feet (0.5 m) are further studied. Earth Systems used methods from Bray et al (2007) to perform the SP117A more -comprehensive quantitative evaluation. This method is used to determine displacement and seek needed ground improvements with structural building improvements or clarify ground improvements are not necessary if structural building improvements are performed. The Bray method uses yield accelerations (ky) values obtained from seismic slope stability analysis in conjunction with spectral acceleration (Sa) associated with the slopes corrected period. Spectral acceleration was based on USGS data for a 2% in 50 year probability of exceedance for the Maximum Credible Earthquake and a 50% probability of exceedance for displacements. Earth Systems used Rocscience's Slide07 to evaluate multiple Ky value scenarios. Seismic shear strength values inputted into the slope stability program used three different methods. Liquefaction layers showing FOS < 1.0 used shear strength values derived from Stark al et (1992). Cohesionless layers with FOS > 1.0 used friction angles that were reduced by 0.65. Cohesive layers used the undrained shear strength of the material. As shown in the fourth column of Table 2, further displacement analysis indicates Lot 175 representing CPT-9 (see Figure 1) requires ground improvement mitigation measure as discussed in Section 5.1 of this report. EARTH SYSTEMS SOUTHWEST May 30, 2017 15 Table 2 Estimated Lateral Displacement (DH) File No.: 09305-31 Doc. No.: 17-05-708R z Exploration Designation Exploration Date Winn (ft) Zhang et al (2004) Estimated Displacement (inches) Bray et al (2007) CPT-4 2003 1.1 NA CPT-7 2017 3.7 9 CPT-8 2017 6.4 12 CPT-9 2017 8.9 89 3.6.3 Review of Current Subsidence Information Earth Systems 2012 past reports have detailed information on subsidence potential at this project. The latest report for subsidence information (Sneed, Michelle, Brandt, J.T., and Solt, Mike, 2014, Land Subsidence, Groundwater Levels, and Geology in the Coachella Valley) indicates Andalusia project lies within a subsidence study area "La Quinta (Area 3)" as `shown below. The project appears to be in a transitional area between green and yellow, which is roughly half the 410-mm (1.35 feet) subsidence value provided in the figure's legend. Tensional stresses and fissuring can occur in transitional areas. e Figure 9 La Quinta Area 3 Subsidence Study Area EARTH SYSTEMS SOUTHWEST May 30, 2017 16 File No.: 09305-31 Doc. No.: 17-05-708R Changes in pumping regimes can ,affect localized, groundwater depths, related cones of depression, and associated subsidence such that the prediction of where fissures or subsidence tensional stresses might occur in the future is very difficult. In the project area, groundwater depths are currently increasing possibly due to groundwater recharging upstream from the project. Based on the historic groundwater contours at approximately -80 feet MSL (California Department of Water Resources, 1964), the project site has experienced groundwater lowering and rising since 1961. However, 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. Figure 10 Close-up of Andalusia Project in La Quinta Area 3 3.6.4 Site Reconnaissance for Subsidence Related Distress On March 2, 2017, an Earth Systems senior geologist walked theperimeter of Andalusia Coral Mountain project to observe existing improvements with a view to looking for potential subsidence related distress. Twenty-two locations were noted with cracking or sinkholes: six sinkholes, eleven perimeter wall cracks, three asphalt concrete cracks, and two sidewalk cracks. EARTH SYSTEMS SOUTHWEST May 30, 2017 17 File No.: 09305-31 Doc. No.: 17-05-708R The sinkholes could not be determined to be subsidence related because the sinkholes were small and appeared to be compaction related to the improvements (trench, vaults, manholes, etc). Cracks along the perimeter wall ranged from hairline to approximately %-inch. The majority of the cracks measured were hairline to %-inch. The largest crack recorded measured %-inch. At this location, the wall was noted as having a crack at the top (cap) and no crack at the base, which is typical for minor settlement. It should also be noted that one wall crack was repaired, but this also showed cracking at the top of the wall and zero at the base. Per engineering guidance, (Day, Table 4.2, page 73) foundation cracks ranging between 0.1 inch to 0.2 inches have a "Damage Category".of "Slight", which Day defines: "Slight damage includes cracks that can be easily filled and redecoration would probably be required; several slight fractures may appear showing on the inside of the.building; cracks that are visible externally and some repainting may be required; and doors and windows may stick." The site visit revealed Minor distress cracking along the perimeter block walls, however, the cracks looked generally settlement related due to the larger gaps at the top versus the bottom (it is our experience that tensional stress related subsidence cracks are consistent thickness top to bottom). From visual observations, the cracking is generally "minor", from an engineering and stability perspective. The asphalt concrete and sidewalk 'cracks were minor and likely related to shrinkage. For additional information on subsidence evaluation, please see Earth Systems "Summary of Preliminary Fissure Hazards Evaluation" report (Earth System, Doc No.: 12-09-715). 3.7 Flooding The project site lies within two designated FEMA Zones: Flood Zone X and Flood Zone D (see figure below). Their FEMA definition is provided below! Flood Zone X -- "Areas of 0.2% annual chance flood; areas of 1% annual chance flood with average depths of less than 1 foot or with drainage areas less than 1 square mile; and areas protected by levees from 1% annual chance flood." Flood Zone D -- Areas in which flood hazards are undetermined, but possible. This is shown on FEMA Panel 2925 of 3805 Map Number 06065C2925G effective 8/28/2008. The project site is in an area where sheet and concentrated flow and erosion could occur. Appropriate - project design by the civil engineer, construction, and maintenance can minimize the sheet flooding potential. EARTH SYSTEMS SOUTHWEST May 30, 2017 r 18 File No.: 09305-31 Doc. No.: 17-05-708R t��•t Sd0• GNS000 FT ;JOINS PANEL 2269 6570000 FT 6675000 FT 3�•3T30' Andalusia Project y -PSI<jE' 2170000 FT �-� _•� �• o ��" C nincorporatrd Area�� d ',+ �, � �� `'� � �' ZONE X „ — • ,4 •City of o 1 Quinta GOT" A RUE s+ems ♦ • . r } ♦ e . •• • .. •� ' �:� i� +, ♦~ ! 2165000 FT �•�♦yYc♦ �• � � ♦ ••' :♦f � / il' i 'i •"•-i�i �7.t t • • �• rrr♦•. * 4� �� Y- � �ram,. .*•.o .. .r, :tirr:-c°l •4, �. Zp E�tX. X. '•:• ail• •• : •: •• eL • • : ! e t •'• 6 S'• '♦'.• i •: •• 1• '.: .':.•. i . t 67AbANEfAlE . • •••• i Figure 11 Excerpt FEMA Flood Map ; EARTH SYSTEMS SOUTHWEST May 30, 2017 19 File No.: 09305-31 Doc. No.: 17-05-708R Section 4 CONCLUSIONS AND GENERAL RECOMMENDATIONS The following is a summary of our conclusions and professional opinions based on the data obtained from a review of selected technical literature, site exploration, and lab testing. Geotechnical Constraints and Mitigation: ➢ California Building Code requirements for the determination of earthquake magnitude and peak ground acceleration has increased both these values from our original report. ➢ Groundwater levels are increasing in the project area and, per CVWD, could rise to historic. levels or higher. CVWD states the existing tile drain system (approximately'10 feet below original grade) controls.groundwater levels. As this tile drain system was installed in the 1950s and 60s, it's a continued function and location near the site should be verified .with CVWD by the project civil engineer. ➢ We recommend the project civil engineer understand the tile drainage system, including research to understand the depth, locations, maintenance plan, loss of tile drain systems due to development or sediment buildup, etc. Earth Systems recommends that the client construct monitoring wells along Avenue 60 to monitor groundwater development since s the trendline indicates within the next 4 years, historic groundwater level increases could take place near the recharging facility. ➢ Earth Systems assumed that groundwater levels. could rise beyond historic levels given' current levels and trends, to a -70 foot elevation. Groundwater levels should be monitored by the client. ➢ Estimated liquefaction settlement due to higher groundwater increased the potential for differential settlement. ➢ Lateral spreading was calculated to exist at all lots except Lot 187. Large scale displacements were found for Lot 175 with an estimated displacement of 89 inches. This lot requires a structural foundation for liquefaction based settlement concern (Life - Safety) and ground mitigation to lessen the lateral spread potential, see Section 5.1. ➢ Lateral spreading for Lots 98, 99, 100, 101, 102, 180, and 187 were estimated to be small scale displacements, which can be mitigated for the home from a Life -Safety perspective using reinforced structural foundations and post -design earthquake repair. No ground mitigation is needed unless desired for flatwork, pools, etc. Lots 98, 99, 100, 101, 102, and 180 have an estimated displacement of less than 12 inches. ➢ For lots experiencing small lateral spreading displacements, should pools, hardscape, etc be desired to resist lateral spreading, they should be designed to be monolithic with grade beams to tie components together and resist 1 foot of movement on those lots. As they are not Life -Safety components of the home structure, specific recommendations (outside of static settlement concerns) are not provided in this report. Pressure jacking to* relevel could be required after a design seismic event. ➢ The recommended use of stiffened footings (grade beams, etc.) and stiffened slab (post - tension, etc.) foundation system are presented. EARTH SYSTEMS SOUTHWEST May 30, 2017 20 File No.: 09305-31 Doc. No.: 17-05-708R ➢ Unchecked groundwater rise to higher than 5 feet below the bottom of footings of an example 3.5 x 3.5-foot footing could reduce the allowable bearing stress by approximately 1000 psf. Actual bearing values will vary depending on footing size and separation between groundwater and bottom of footing. ➢ If groundwater rises to within 5 feet of the bottom of footings, the bearing pressures provided should be reduced. ➢ Recommendations are provided within to reduce the potential for damaging tensional stress to the proposed residences, as well as structural support of appurtenant structures such as pools, fence walls, and flatwork based on estimated settlements from liquefaction and dry seismic, lateral spreading, and static loading 'conditions. However, these structures may also be subject to unpredictable tensional stresses from future movement that may cause separations and cracking. Based on our current field. reconnaissance and research during the preparation of this report, subsidence ;related distress (tension stress, fissuring, etc) does not appear to be occurring'at this time; therefore, Earth Systems provides recommendations for augmented foundation design based on our estimated settlements stated above (liquefaction, dry seismic, and static loading). Pads, flatwork, etc may be damaged by lateral, spreading. Life safety recommendations are provided to reduce the potential for life safety issues regarding the house structure. ➢ 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. ➢ As the -degree of continued groundwater pumping/recharge, pumping/recharge patterns, subsurface flow patterns, and their combined effect on the overlying soil settlements from subsidence, liquefaction, and lateral spreading is .variable, 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, liquefaction, and lateral spreading is more fully understood. ➢ It is our opinion that the recommendations provided in the project soils report (Earth Systems, 2003) and (Earth Systems, 2012, Doc No.: 12-11-704), as supplemented and superseded in the following, remain applicable provided they are incorporated into the design and construction. EARTH SYSTEMS SOUTHWEST May 30, 2017 Section 5 RECOMMENDATIONS. 5.1 Site Development —Grading 21 File No.: 09305-31 Doc. No.: 17-05-708R It is our opinion that the recommendations provided in the project soils reports (Earth Systems, 2003) and (Earth Systems, 2012, Document No.: 12-09-704), where needed, as supplemented and superseded below, remain applicable provided the following recommendations are incorporated into the design and construction. 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 when performed with walk -behind equipment, where the grade is not increased more than one foot from original design grade or where approved by the building official. . Pool Under pool/spa decks and pool/spa bottoms, the upper 12 inches of soil below the finish subgrade should be compacted to at least 95% relative compaction at near optimum.moisture content. These grading recommendations for pools are based on the shell withstanding an estimated angular distortionjas presented on Figure 13. Actual static settlements of the pool should be performed on a case by case basis. Light and Flag Poles Construction employing flagpoles or posts may utilize design methods presented in Section 1807A of the CBC for sand with silt and silty sand; (SP-SM, and SM) material class. For miscellaneous structural components, such as light poles, gate posts, temporary retaining walls, and flag poles less than 12 feet in embedment length, which are supported on cast -in -place piles, or direct embed in drilled holes filled with concrete, for designs utilizing allowable frictional resistance only (no over -excavation necessary), Earth Systems recommends the use of Section 1810.3.3.1.4 of the CBC. These design methods apply for piles spaced at least.three pile diameters center to center for axial loads and at least six pile diameters center to center for lateral loads. Piles spaced closer may have a soil strength reduction, therefore, should be evaluated on a case - by -case basis by geotechnical engineer. Lateral Spreading Mitigation As identified in Section 3.6.2, one CPT location (CPT-9, identified on Figure 1) showed 'large" horizontal displacement values, which triggers a requirement for ground mitigation measure/s. This CPT exploration represents Lot 175. The other Lots (98, 99, 100, 101, 102, 180, and 187), do not require this mitigation; having estimated displacements on the order of 1 foot or less, which EARTH SYSTEMS SOUTHWEST l May 30, 2017 22 File No.: 09305-31 Doc. No.: 17-05-708R typically can be accounted for in the house structure design for Life -Safety as presented within Section 5.4 (Grade beams, structural stiffened slab). Appurtenant hardscape, pools, etc could be damaged and require repair after a seismic event. For this report, Earth Systems provides one mitigation measure (drilled shaft with I -Beam) but this does not preclude the use of other types of mitigation measures or a combination of mitigation measures, which could be more economical, that may include: 1. Permeation Grouting (permeate into clean sands) 2. Chemical Grouts 3. Compaction Grout (limit = confining stress'> 6-meter depth) 4. Vibratory Probes 5. Vibro Replacement 6. Drains for Liquefaction 7. Compaction Piles 8. Jet Grouting 9. Admixtures 10. Deep Soil Mixing 11. Remove and Replace Please contact Earth Systems for a specialty contractor experienced with these techniques. Some specialty contractors that Earth Systems has worked with are Hayward Baker and Menard; however, additional contacts are available. Displacement analysis for CPT-9 indicated large displacements using the Bray at el, (2007) method of analysis. Shear strength parameters for a 60-foot soil profile for the onset or trigger of liquefaction was estimated by the relationship presented by Stark and Mesri (1992). A slope stability analysis using Rocscience Slide07 was performed using a critical seismic coefficient (ky) analysis. Using various critical seismic coefficients from the stability analysis, displacements were obtained using Bray et al. method. Additional slope stability analysis was performed to determine the loading requirements for the concrete shaft with encased I-beam. Lots 175 (CPT-9) Earth Systems performed a slope stability analysis on CPT-9 and this was used to represent lot_ 175. In this analysis, we used distances as depicted in Figure 12 below. Our analysis of Lot 175 had a pad elevation of-433 and an estimated lake bottom of 400. We used the 2003 mass grading plans to define the soil profile. From the figure, below and the elevation data provided, the "X" distance is approximately 63 feet, which starts.at a depth of 30 feet below the bottom of the lake. Slope stability results indicate the design of the concrete shaft shall provide for a triangular distributed maximum pressure of 1.5 x 6,750 Ib/sgft and a base shear value of approximately 1.5 x 6,500 lbs. Based on explorations from an earlier report (Earth Systems, 2012), Earth Systems estimates a soil friction angle of 29 degrees may be used for preliminary design purposes. Actual soil properties should be explored during the design of the concrete shafts and verified during construction. The design engineer in conjunction with Earth Systems should provide the actual value for "dr" shown in Figure 12, of the concrete shaft, once pile shaft properties are selected. Earth Systems recommends that shafts be reinforced with an I-beam rather than spiral reinforcement. EARTH SYSTEMS SOUTHWEST May 30, 2017' 23 File No.: 09305-31 Doc. No.: 17-05-708R tro"ss'SectionProfile Triangutar Max P.'ressu' 'Pad.Grad lope Slide surf is _ Cake Surface_ 30 k m nib mum i Concrete Shali w%1-Se' , of Lake 0.ofsoo r r Plan View 4 ft;Con4rete Shah . 4l_bearr.,,b House, slope on Conception Profile and Plan View "Lake I � . r') �� Earth Systems does not practice structural engineering. The above shaft design dimensions, are estimates and the design of the concrete/I-beam shaft is the responsibility of the structural engineer or specialty engineer. Earth Systems should review the design of the shaft foundation and passive pressure diagram for resisting force of the concrete shaft. ,5.2 Excavations and Utility Trenches 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 t officiaL, 5.3 . Slope Stability of Graded Slopes All slopes will be exposed to weathering, resulting in decomposition of surficial earth materials, thus potentially reducing shear strength properties of the surficial soils. In addition, these slopes become increasingly susceptible•to rodent burrowing. EARTH SYSTEMS SOUTHWEST May 30, 2017 24 File No.: 09305-31 Doc. No.: 17-05-708R As these slopes deteriorate, they can be expected to become susceptible to surficial instability such as soil slumps, erosion, soil creep, and debris flows. Development areas immediately adjacent to ascending or descending slopes should address future surficial sloughing of soil material. Such measures may include maintenance requirements, debris fences, liners, catchment areas or walls, ditches, slope facing, soil planting or other techniques to contain soil material. Homeowner, and operation and maintenance inspections (of common areas) should be done after a significant rainfall event and on a time -based criteria (annually or less) to evaluate distress such as erosion, slope condition, rodent infestation burrows, etc. Inspections should be recorded and photographs taken to document current conditions. The repair procedure should outline a plan for fixing and maintaining surficial slope failures, erosional areas, gullies, animal burrows, etc. Repair methods could consist of excavating and infilling with compacted soil erosional features, track walking the slope faces with heavy equipment, as determined by the type and size of repair. These repairs should be performed in a prompt manner after their occurrence. Design slope inclinations should be maintained and a maintenance program should include identifying areas where slopes begin to steepen. Where future maintenance is not possible, slopes should be faced to reduce the erosion and degradation potential. 5.4 Stiffened Foundations and Stiffened Slabs It is our opinion that the recommendations provided in the project soils report (Earth, Systems, 2003), as supplemented and superseded below, remain applicable provided the following recommendations are incorporated into the design and construction. Based upon the information provided in Sections 3.6.1 and 3.6.2 (Liquefaction and Lateral Spreading) of this report and Section 1.1 of the project geotechnical report (Earth Systems 2003), we recommend that structures be designed to withstand a potential Angular Distortion as shown in the figure below. As shown in the figure below, Lots 98, 99, 100, 101, 102, 175, and 180 should be designed using a distortion angle of 1:190, which is equivalent 2.5 inches in 40,feet of differential settlement. Lot 187 should be designed using an angular distortion of 1:410, which is equivalent to 1.15 inches in 40 feet of differential settlement. EARTH SYSTEMS SOUTHWEST • 1 r ` May 30, 2017 25 File No.: 09305-31 Doc. No.: 17-05-708R AVEMM 54 % �jI1T� ' � . , � • �rl, 4 T .}• �' Q Lots 98' 99,,100 101 and 102: �` Distortion Angle:l 1901 . L71ot t75 CPT-9,(2017): Distortion Angte 1 190" • 1 en Lot 180 GPT-8'(201.7). Distortion Angle`11.80r 4' `\' t'r %ter = —s ' ,, LotJ87, CPT=4,(2003)' DistoitionAn'1e.1:410: ., ANOAIUSlA TRACT 31681 . � -,_ ------'------�-.._.raveram'io'------•---.--"_..------ .t'' maq Figure 13 Area Distribution Map for Distortion Angles Earth Systems experience with angular distortions call for stiffened foundations and stiffened . slabs. Stiffened foundations typically consist of a structural slab (post -tension, waffle, mat, + thickened & reinforced) with integral footings and/or grade beam footings with a waffle slab and stiffened shear walls, including any overhang canopy areas. At garage door openings, a minimum of 18"x18" grade beams should be utilized between the open span. It is our opinion that the Andalusia project should consider the use of these types of measures to reduce the potential for future home distress, given the current knowledge of seismic settlement and lateral spreading. Except for Lot 175, differential movement is not expected to result in a complete unsupported loss of subgrade support, but, rather a tilting of the structure. Pressure grouting could be required to re -level structures after a design earthquake. The following recommendations are based on "Very Low" to "Low" expansion category soils in the upper five feet of subgrade. Soils which are found to be more expansive than a "very low" Expansion Index will require differing foundation requirements which should be provided.on a case by case basis. Footing design of widths, depths, and reinforcing 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 for wall footings and 18 inches for column footings below lowest adjacent grade should be maintained (lowest grade within 2 feet laterally as measured from the foundation bottom). Earth Systems should be retained to observe foundation excavations before placement of reinforcing steel or concrete. Loose soil or construction debris EARTH SYSTEMS SOUTHWEST May 30, 2017 26 File No.: 09305-31 Doc. No.: 17-05-708R should be removed from footing. excavations before placement of concrete. All footing excavations should be probed for uniformity. Soft or loose zones should be excavated and recompacted to finish foundation bottom subgrade. The bottom of all foundations should be tested to confirm a minimum of 90% relative compaction (ASTM D 1557). Slope Setback for Foundations: Based on our lateral spreading analysis, Earth Systems recommends buildings with maximized setback distances. Where ground modifications are provided, the above stated maximum setback need not apply. The 2016.California Building Code provides setback distances for foundations along slopes. Setback distances are measured differently for foundations located above the slope and those located below the slope. For foundations located at the top of the slope, the measurement is taken horizontally from the outside face of the foundation footing to the face of the slope. For foundations located below the slope, the horizontal distance is measured from the face of the structure to the top of the slope. For pools and slopes steeper than 1(H):1(V), please contact Earth System for these setbacks with submittal of detailed information using plan form. Stiffened Foundation & Stiffened Slab Foundations: Allowable soil bearing pressures are given below for foundations bearing on recompacted. soils as described in Section 5.1 of the project geotechnical report. Allowable bearing pressures are net (weight of footing and soil surcharge may be neglected). The allowable bearing values presented are based on the anticipated maximum loads of 25 kips for isolated spread footings (3.5'x 3.5' maximum) and 2.0 kip/ft for continuous footings. If the anticipated loads exceed these values, the geotechnical engineer must reevaluate the allowable bearing values as the allowable bearing was controlled by the allowable settlement such that total settlement due to static and seismic- is kept at less than 1 inch. ➢ Continuous wall foundations, 12-inch minimum width and 12-inch minimum embedment depth: 1,500 psf for dead plus design live loads Allowable increases of 300 psf per each foot of additional footing width may be used to a maximum of 3000 psf. However, no increase for.depth unless a grading report review of the over -excavation depth indicates greater than 3 feet of over -excavation has occurred or client agrees to recompact the pad area. ➢ Pad foundations, 2 x 2 foot minimum and 3.5 x 3.5-foot maximum in plan and 18 inches below grade: 2,000 psf for dead plus design live loads Allowable increases of 200 psf per each foot of additional footing width may be used to a maximum of 3000 psf. However, no increase for depth unless a grading report review of the over -excavation depth indicates greater than 3 feet of over -excavation has occurred or client agrees to recompact the pad area. Based on information from the groundwater section of this report, the rise of groundwater within five feet of the bottom of a 3.5 x 3.5-foot footing will reduce the bearing stress of the footings. EARTH SYSTEMS SOUTHWEST May 30, 2017 27 File No.: 09305-31 Doc. No.: 17-05-708R Without specific data, the bearing stress would be reduced by 1000 psf. Groundwater should be controlled to be deeper than 5 feet below the footing bottom or allowable bearing be reduced and provided on a case by case basis. All pad foundations and isolated foundations should be tied to the main foundations system utilizing grade beams. At garage door openings, a minimum of 18"x18" grade beams should be utilized. A one-third (A) increase in the allowable bearing pressure may be used when calculating resistance to wind or seismic loads. The spacing between any large spread footings should be evaluated by the geotechnical engineer during the plan review stage to confirm or modify the settlement estimates and bearing capacity due to large footings and the influences from adjacent footings. A preliminary analysis suggests spacing the footings (adjacent edge to adjacent edge) a lateral distance from one another of twice the width of the largest footing from any adjacent footing, such that influence effects are minor. Maximum foundation sizes given above are based on settlement due to Dead + Live loads. Transient loads such as earthquake or wind loads are not subject to the stated size limitations; however, the allowable bearing pressure (including % increase) should be followed considering the relevant foundation sizes given above. An average modulus of subgrade reaction, k, of 200 pounds per cubic inch (pci) can be used to design lightly loaded footings and slabs. founded upon compacted fill. Other foundations such as mat slabs, will require the use of differing modulus of subgrade reaction values than used for lightly loaded slabs, and can be provided on a case -by -case basis. Minimum Foundation Reinforcement: Minimum reinforcement should be provided by the structural engineer to accommodate the settlement potentials presented within. Minimum reinforcement for continuous wall footings should be four, No. 4 steel reinforcing bars, two placed near the top and two placed near the bottom of the footing. This reinforcing is not intended to supersede any structural requirements provided by.the structural engineer. 5.4.1 Estimated Settlements for Shallow Foundations , Estimated total static settlement should be less than one inch, based on footings founded on firm. soils as recommended. Total seismic settlement is, estimated to range between 1.3 and 5.3 inches. Therefore, total settlement settlements range between 2.3 and 6.3 inches. The total' estimated differential'settlement for the combined static and seismic settlement is estimated to 11.15" (calculated) for Lot 187 and 2.5" (calculated) for lots: 98, 99, 100, 101, 102; 175, and 180. As such,; considering both static and seismic differential settlement applied over a typical foundation distance of 40 feet, we recommend the structural engineer design for the standard angular distortion shown in Figure 13 on page 25 of this report, which is not the typical standard of care for residential structures without structural measures (County, 2000, page 39). EARTH SYSTEMS SOUTHWEST May 30, 2017 28 File No.: 09305-31 Doc. No.: 17-05-708R 5.5 Slabs -on -Grade Vapor Retarder: In . areas of moisture -sensitive . floor coverings, coatings, adhesives, underlayment, goods or equipment stored in direct contact with the top of the slab, bare slabs, humidity controlled environments, or climate -controlled cooled environments, an appropriate vapor retarder that maintains a permeance of 0.01 perms or less after ASTM E1745's mandatory conditioning tests should be installed to reduce moisture transmission from the subgrade soil'to the slab. For these areas, a vapor retarder (Stego wrap 15=mil thickness or equal) should underlie the floor slabs. If a Class A vapor retarder (ASTM E 1745) is specified, the retarder can be placed directly on non -expansive soil, and be covered with a minimum of two inches of clean sand. Clean sand is defined as well or poorly=graded sand (ASTM D 2488) of which less than five percent passes the No. 200 sieve and all the material passes a No. 4 sieve. The site soils do not fulfill the criteria to be considered clean sand. Alternatively, the slab designer may consider the use of other vapor retarder systems that are recommended by the American Concrete Institute. Low -slump concrete should be used to help reduce the .potential for concrete shrinkage. The effectiveness of the membrane is dependent upon its quality, the method of overlapping; its. protection during construction, the successful sealing of'the membrane around utility lines, and sealing the membrane at perimeter terminations and all penetrations. Capillary breaks, if any, beneath slabs should,consist of a minimum of at least four inches of permeable base material with the following specified gradation. Sieve Size Percent Passing 1 inch 100 3/ Inch 90-100. 3/8'Inch 40-100 #4 25-40 #8 18-33 #30 5-15 #50 0-7 #200 0-3 Where vapor retarders are placed directly on a gravel capillary break, they should be a minimum of 15 mil thickness. Where concrete is placed directly on the vapor retarder "plastic", proper curing techniques are essential to minimizing the potential of slab edge curl and shrinkage cracking. The edges of slabs can curl upward because of differential shrinkage when the top of the slab dries to lower moisture content than the bottom of the slab. Curling is caused by the difference in drying shrinkage between the top and bottom of the slab. Curling can be exacerbated by hot weather, or dry condition concrete placement, even with proper curing techniques. EARTH SYSTEMS SOUTHWEST May 30, 2017 5.6 Retaining Walls 29 File No.: 09305-31 Doc. No.: 17-05-708R Earth Pressures: The following table presents lateral earth pressures for use in retaining wall design with a granular backfill. The granular backfill has the following soil properties: Unit Wet Density of 126 pcf, Internal Friction Angle of 32 degrees, Cohesive Strength of 0 psf. The equivalent fluid pressures for seismic values is based on a horizontal seismic acceleration of 0.54 PGAM. The values are given as equivalent fluid pressures without surcharge loads or hydrostatic pressure. Table 3 Retaining Wall Equivalent Fluid Pressures Lateral Pressures and Sliding Resistance 1 Granular Backfill Passive Pressure 350 pcf - level ground Active Pressure (cantilever walls) 50 pcf - level ground Use when wall is permitted to rotate 0.1% of wall height At -Rest Pressure (restrained walls) 65 pcf - level ground Dynamic Lateral Earth Pressure Z Acting at 0.6H, where H is height of granular backfill in feet 13 pcf -flexible wall 26 pcf— rigid wall Notes: 1. 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. 2. Dynamic earth pressures should be estimated by the structuralengineer using methods such as Al Atik and Sitar (2010), or other suitable technique. Walls retaining:less than 6 feet of soil need not consider this increased pressure • Retaining wall foundations should be placed upon compacted fill described in Section 5.1. • 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. J Design should be in accordance with the 2016 California Building Code. Drain rock should be wrapped in filter fabric such as Mirafi 140N as a minimum. Backfill immediately behind the retaining structure should be a free -draining granular material. Waterproofing should be per the designer's specifications. Water should not be allowed to pond or infiltrate near the top of the wall. Toaccomplish this, the final backfill grade should be such that water is diverted away from retaining walls. • 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. EARTH SYSTEMS SOUTHWEST May 30, 2017 30 File No.: 09305-31 Doc. No.: 17-05-708R • 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 three feet away from the walls while the backfill soils are placed. Upward sloping backfill or rock, or surcharge loads from nearby footings can create larger lateral pressures. Should any'walls be considered for retaining sloped backfill (or rock) 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 to at.least 250 psf for auto and pickup traffic or 450 psf for.larger vehicles at least three feet from the back of 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 may be taken as equivalent to the pressure exerted by a fluid weighing 350 pounds per cubic foot (pcf) which includes a 1.5 Factor of Safety. Vertical uplift resistance may consider a soil unit weight of 100 pounds per cubic foot. The upper one 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 350 pcf. The maximum passive resistance should not exceed 2,000 psf. • 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. EARTH SYSTEMS SOUTHWEST May 30, 2017 31 File No.: 09305-31 Doc. No.: 17-05-708R 5.7 Mitigation of Soil Corrosivity on Concrete As such, we recommend an engineer competent in corrosion mitigation review these results and design corrosion protection appropriately. Additionally, we recommend samples of building pad soils should be observed or tested prior to footing excavation to allow and engineer competent in corrosion analysis to evaluate the results in relation to other constituents, that may be of concern such as nitrates, ammonium, etc. 5.8 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 faults. Engineered design and earthquake - resistant construction increase safety and allow development of seismic areas. The minimum seismic design should comply with the 2016 edition of the California Building Code [CBC] and ASCE 7-10 (with' July 2013 errata) using the seismic coefficients given in the table below. Sites susceptible to liquefaction are typically classified as Site Class F. However, as allowed by ASCE7-10 and the 2016 CBC, for sites not susceptible to liquefaction bearing capacity failure and building periods less than 0.5 seconds, the site can be classified based on typical ASCE 7-10 procedures. Based on the above information, we classify the site soil profile for site response as D according to Table 20.3-1 of ASCE7-10. The D characterization is defined as a soil profile consisting of stiff soil with shear wave velocities between 600 and 1,200 ft/s. Seismic parameters are based upon computation by the Ground Motion Parameter Calculator provided by the United States Geological Survey [USGS] at: http://earthquake.usgs.gov/designmaps/us/application.php (March 8, 2017). Structure periods greater than 0.5 seconds will require a site -specific evaluation as the parameters presented below would not be valid for design. Site grading has been performed and/or recommended to reduce the potential for bearing failure in conjunction with recommendations for increased structural design. Site Location: Site Class: Table 4 2016 CBC Seismic Coefficients 33.62045°N/116.2345°W F/D Maximum Considered Earthquake [MCE] Ground Motion Short Period Spectral Response SS: 1.500 g 1 second Spectral Response, Si: 0.618 g Design Earthquake Ground Motion Short Period Spectral Response, Sys 1.000 g 1 second Spectral Response, Sal 0.618 g PGAM 0.54 g The intent of the CBC lateral force requirements are to provide a structural design that will resist collapse to provide reasonable life safety from a major earthquake, but may experience some structural and nonstructural damage. A fundamental tenet of seismic design is inelastic yielding EARTH SYSTEMS SOUTHWEST May 30, 2017 32 File No.: 09305-31 Doc. No.: 17-05-708R 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 the design plans and good construction practices are followed. Thi's is especially important for sites lying close to major seismic sources. Design peak horizontal ground accelerations are estimated to be approximately 0.73 g. Vertical accelerations are typically 1/3 to 2/3 of the horizontal acceleration, but can equal or exceed horizontal accelerations depending upon underlying geologic conditions and basin effects. Earthquake Performance Statement Depending upon the extent of structural and geotechnical design of 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 the Coachella Valley and 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. 5.9 Site Drainage and Maintenance Positive drainage in native soils should be maintained away from the structures (5% for 5 feet minimum) to prevent ponding and subsequent saturation of the foundation soils. Gutters and downspouts in conjunction with a 1 to 2% paved or hardscape grade should be considered as a means to convey water away from foundations if increased fall is not provided. Drainage should be maintained,for all areas. Water should not pond on or near paved areas or foundations. The following recommendations are provided in regard to site drainage and structure performance: i • In no instance, should water be allowed to flow or pond against structures, slabs or foundations or flow over unprotected slope faces. Adequate provisions should be employed to control and limit moisture changes in the subgrade beneath foundations or structures to reduce the,potential for soil saturation and erosion. Landscape borders should not act as traps for water within landscape areas. Potential sources of water such as piping, drains, broken sprinklers, etc., should be frequently examined for leakage or plugging. Any such leakage or plugging should be immediately repaired. EARTH SYSTEMS SOUTHWEST May 30, 2017 33 File No.: 09305-31 Doc. No.: 17-05-70813 • It is highly recommended landscape irrigation or other sources of water be collected and conducted to an approved drainage device. Landscaping and drainage grades should be lowered and sloped such that water drains to appropriate collection and disposal areas. All runoff water should be controlled, collected, and drained into proper drain outlets. Control methods may include curbing, ribbon gutters, 'V' ditches, or other suitable containment and redirection devices. • Maintenance of drainage systems and infiltration structures (basins) can be the most critical element in determining the success of a design. They must be protected and maintained from sediment -laden water both during and after construction to prevent clogging of the surficial soils and any filter medium. The potential for clogging can be reduced by pre -treating structure inflow through the installation of maintainable forebays, biofilters, or sedimentation chambers. In addition, sediment, leaves, and debris must be removed from inlets and traps and basin bottoms on a regular basis, and basin bottoms must have silt soils removed periodically from the bottom. The drainage pattern should be established at the time of final grading and maintained throughout the life of the project. Additionally, drainage structures should be maintained (including the de -clogging of -piping, basin bottom scarification and removal, etc.) throughout their design life. Maintenance of these structures should be incorporated into the facility operation and maintenance manual. Structural performance is dependent on many drainage - related factors such as landscaping, irrigation, lateral drainage patterns and other improvements. EARTH SYSTEMS SOUTHWEST May 30, 2017 34 File No.: 09305-31 Doc. No.: 17-05-708R Section 6 LIMITATIONS AND ADDITIONAL, SERVICES 6.1 Uniformity of Conditions and Limitations Our findings and recommendations in this report are based on selected points of 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. 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 and scope. If the scope of the proposed construction changes from that described in this report, the conclusions and recommendations contained in this report are not considered valid unless the changes are reviewed, and the conclusions of this report are modified or approved in writing by Earth Systems. Findings of this report are valid as of the issued date of the report. However, 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. If during construction, soil conditions are encountered which differ from those described herein, we should be notified immediately in order that a review maybe made and any supplemental recommendations provided: In such an event, the contractor should promptly notify the owner so that Earth Systems geotechnical engineer can be contacted to confirm those conditions. We recommend the contractor describe the nature and extent of the differing conditions in writing and that the construction contract include provisions for dealing with differing conditions. Contingency funds should be reserved for potential problems during earthwork and foundation construction. This report is issued with the understanding that the owner or the owner's representative has the responsibility to bring the information an.d recommendations contained herein to the EARTH SYSTEMS SOUTHWEST May 30, 2017 35 File No.: 09305-31 Doc. No.: 17-05-70811 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 verify 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. 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 reviewed for applicability and conformance to the current design and incorporated into the plans for the project. Earth Systems has striven to provide our services in accordance with generally accepted geotechnical engineering practices in this locality at this time. No warranty or guarantee, express or implied, is made. This report was prepared for the exclusive use of'the Client and the Client's authorized agents. Demolition, grading and compaction operations should be performed in conjunction with observation and testing. The recommendations provided in this report are based on the assumption that Earth Systems will be retained to provide observation during the construction phase to evaluate our recommendations in relation to the apparent site conditions at that time. If we are not accorded this observation, Earth Systems assumes no responsibility for the suitability of our recommendations. In addition, if there are any changes in the field to the plans and specifications, the Client must obtain written approval from Earth Systems engineer that such changes do not affect our recommendations. Failure to do so will vitiate Earth Systems recommendations. These services will be performed on a time and expense basis in accordance with our agreed upon fee schedule once we ' are authorized and contracted to proceed. Maintaining Earth Systems as the geotechnical consultant from beginning to end of the project will provide continuity of services. The geotechnical engineering firm providing tests and observations shall assume the responsibility of Geotechnical Engineer of Record. Any party other than the'dient who wishes to use this report shall notify Earth Systems of such intended use. Based on the intended use of the report, Earth Systems may require that additional work be performed and that an updated report be issued. Non-compliance with any of these requirements by the client or anyone else will release Earth Systems from any liability resulting from the use of this report by any unauthorized party. 6.2 Additional Services . This report is based on the assumption that an adequate program of client consultation, construction monitoring, and testing will be performed during the final design and construction phases to check compliance with these recommendations. Maintaining Earth System as the geotechnical consultant from beginning to end of the project will provide continuity of services. Proper geotechnical observation and testing during construction is imperative to allow the geotechnical engineer the opportunity to verify assumptions made during the design process and to verify that our geotechnical recommendations have been properly interpreted and implemented during construction and is required by the 2013/2016 California Building Code. Therefore, we recommend that Earth Systems be retained during the construction of the EARTH SYSTEMS SOUTHWEST May 30, 2017 36 File No.: 09305-31 Doc. No.: 17-05-708R 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. Additionally, the California Building Codes requires the testing agency to be employed by the project owner or representative (i.e. architect) to avoid a conflict of interest if employed by the contractor. Construction monitoring and testing would be additional services provided by our firm. The costs of these services are not included in our present fee arrangements, but can be obtained from our office. The recommended review, tests, and observations include, but are not necessarily limited to, the following: • Consultation during the final design stages of the project. • Observation and testing during site preparation, grading, and placement of engineered fill and Special Inspection as required by CBC Sections or local grading ordinances. •. Consultation as needed during construction. -000- • Appendices as cited are attached and complete this report. EARTH SYSTEMS SOUTHWEST May 30, 2017 37 File No.: 09305-31 Doc. No.: 17-05-708R REFERENCES Al Atik; L., and Sitar, N., 2010, Seismic Earth Pressures on Cantilever Retaining Structures, Journal of Geotechnical and Geoenvironmental Engineering, ASCE. American Concrete Institute (2014) "Building Code Requirements for Structural Concrete (ACI 318- 14) and Commentary (ACI 318R-14)." American Society of Civil Engineers [ASCE], 2010, Minimum Design Loads for Buildings and Other Structures, ASCE 740. Boulanger, R. W., and Idriss, I. M., 2006, Liquefaction Susceptibility Criteria for Silts and Clays, J. Geotechnical and Geoenvironmental Eng., ASCE 132 (11), 1413-1426. Bray, D., Jonathon, P.K., and Travasarou, Thaleia. (2007). Simplified Procedure for Estimating Earthquake -Induced Deviatoric' Slope Displacements, J., Geotech. Geoenviron. Eng., 133(4): 381-392. Buena Engineers, Inc., 1990, Geotechnical Feasibility Report, Rancho La Quinta (560 Acres), La Quinta Area, Riverside County, California, File No.: 137-2333-131, Doc No.: 90-05-822, dated May 18, 1990. California Department of Water Resources, 1964, Coachella Valley Investigation, Bulletin No. 108, 146 pp. California Geologic Survey-SP117A, 2008, Guidelines for Evaluating and Mitigating Seismic. Hazards in California. City of La Quinta, 201-7, Engineering Plan Archive, Plan Set No. 04001, Mass Grading Plan Coral Mountain, Seven Sheets. County of Los Angeles, 2014, Guidelines for Design, Investigation, and Reporting Low Impact Development Storm Water Infiltration, Administration Manual Department of Public Works, Geotechnical and Materials Engineering Division, 38 pages, online. County of Riverside, Geographic Information Services (GIS), Transportation and Land Management Agency, http://www3.tlma.co.riverside.ca.us/pa/rclis/indek.htm1. Coachella Valley Water District (CVWD), 2017, "Well Reading at Andalusia", Message to Earth Systems, March 10, 2017. E-mail. Day, Robert W. 1999, Forensic Geotechnical and Foundation Engineering, McGraw-Hill, 460 pages. Dept. of the Navy, 1986, NAVFAC DM 7.01: Soil Mechanics, Naval Facilities Engineering Command, Alexandria, Virginia. Dept. of the Navy, 1986, NAVFAC DM 7.02: Foundations and Earth Structures,. Naval Facilities Engineering Command, Alexandria, Virginia. Earth Systems Southwest, 2003, Geotechnical Engineering Report, Coral Mountain, SEC Madison Street & Avenue 58, La Quinta, California, File No.: 09305-01, Document No.: 03-09-700, dated September 2, 2003. EARTH SYSTEMS SOUTHWEST May 30, 2017 38 File No.: 09305-31 Doc. No.: 17-05-708R Earth Systems Southwest, 2005, Recommended Pavement Sections for Interior Roadways, Andalusia at Coral Mountain, Southeast Corner of Madison Street and Avenue 58, La Quinta, California, File No.: 09305-02, Document No.: 05-03-731, dated March 7, 2005. Earth Systems Southwest, 2005, Addendum to Geotechnical Engineering Report, Andalusia at Coral Mountain, Southeast Corner of Madison Street and Avenue 58, La Quinta, California, File No.: 09305-01, Document No.: 05-06-737, dated June 9, 2005. Earth Systems Southwest, 2005, Geotechnical. Engineering Report, Andalusia at Coral Mountain, West Side Properties, Southwest Corner Madison Street and Avenue 58, La Quinta, California, File NO.: 09305-04, Document No.: 05-05-703, dated July 27, 2005. Earth Systems Southwest,_ 2005, Report of Testing and Observations Performed during Rough Grading, Swimming and Tennis Facility, Andalusia at Coral Mountain, Southeast Corner Madison Street and Avenue 58, La Quinta, California, File No.:09305-02, Document No.: 05-10-809, dated November 28, 2005. Earth Systems Southwest, 2006, Report of Testing and Observations Performed during Rough Grading, Andalusia at Coral Mountain, Southeast Corner of Madison Street and Avenue 58, La Quinta, California, File No.: 09305-02, Document No.: 06-08-719, dated August 4, 2006. Earth Systems Southwest, 2012, GeotechnicalEngineering Report Update, Andalusia at Coral Mountain, Covered Terrace Addition, Southwest Corner Madison Street and Avenue 58, La Quinta, California, File No.: 09305-01, Document No.: 12-09-704, dated September 6, 2012. _Earth Systems Southwest, 2012, Summary of Preliminary Fissure Hazards Evaluation, Andalusia Development, Madison Street & Avenue 58, La Quinta Area, Riverside County, California, File No.: 09305-17, Document No.: 12-09-715, dated September 14, 2012. Earth Systems Southwest, 2012, Updated Geotechnical Engineering Report for Racquet Club Facilities & Residential Improvements, Andalusia at Coral Mountain, La Quinta, Riverside County, California, File No.: 09305-17, Document No.: 12-11-704, dated October 31, 2012 Faris, A.T., 2004. Probabilistic Models for Engineering Assessment of Liquefaction -Induced Lateral Spreading Displacements, Ph.D. thesis, University of California at Berkeley, 436 pp. Faris, A.T., Seed, R.B., Kayen, R.E., and Wu, J., 2006. A Semi -Empirical Model for the Estimation of Maximum Horizontal Displacement Due to Liquefaction -Induced Lateral Spreading, 8th National Conference on Earthquake Engineering, EERI, San Francisco, C.A. Idriss, M., I, and Boulanger, W., R. (2008). Soil Liquefaction During Earthquakes, Earthquake Engineering Research Institute, 2008, book, 237 pages. Ludwig Engineering, 2006, Andalusia at Coral Mountain Rough Grading Plans, Tract No. 31681-3, City of La Quinta PSN 06208, 20 sheets, approval date 11/17/2006. Naeim, Farzad. 1989, The Seismic Design Handbook, Structural Engineering, Van Nostrand Reinhold, New York, 450 pages. Rocscience Inc, 2017, SLIDE - An Interactive Slope Stability Program, Version 7.018 644t, Build date: August 17, 2016. EARTH SYSTEMS SOUTHWEST May 30, 2017 39 = File No.: 09305-31 Doc. No.: 17-05-708R Sneed, Michelle, et al, 2014, Land Subsidence, Groundwater Levels, and Geology in the Coachella Valley, California, 1993-2010, United -'States Geological Survey, Scientific Investigations Report 2014-5075: Southern California Earthquake Center (S.C.E.C.), 1999, Recommended Procedures for Implementation of DMG Special Publication 117, Guidelines for Analyzing and Mitigating Liquefaction in California: available at web site: htt0://www.scecdc.scec.ore. Stark, D., Timothy, and Mesri, Gholamreza, (1992). "Undrained Shear Strength of Liquefied Sands for Stability Analysis "Journal of Geotechnical Engineering., 118(11): 1727-1747:- Tokimatsu, K, and Seed, H.B., 1987, Evaluation of Settlements ,in Sands Due To Earthquake Shaking, ASCE, Journal of Geotechnical Engineering, Vol. 113, No. 8, August 1987. United States Department of the Interior Bureau of Reclamation (USBR), 1989, Performing Field Permeability Testing by the Well Permeameter Method, USBR 7300-89, 1989. Watson,& Watson Engineering, Inc,, 2003,.Mass Grading Plan Coral Mountain, City of La Quinta PSN 04001, 7 sheets, approval date 1/13/2004. Youd, T.L., Hansen C. M., Bartlett. S. F., 2002, Revised Multilinear.Regression Equations for Prediction of Lateral Spread Displacement, ASCE, Journal of Geotechnical Engineering, Vol. 128, No. 12, December 2002. Youd, T.L:, and Idriss, I.M., 2001, Liquefaction Resistance of Soils: Summary Report from the '1996 NCEER and,1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 127, No. 10, October 2001. Zhang, G., Robertson, P.K., and Brachman, R.W.I. (2004). "Estimating Liquefaction -Induced Lateral Displacements Using the Standard Penetration Test. or Cone Penetration Test. "J. Geotech. Geoenviron. Eng., 130(8): 861-871. APPENDIX A Plate 1— Site Vicinity Map Plate 2 — CPT Location Map Terms and Symbols Used on Boring Logs Soil Classification System Log of CPT-4 (2003) Logs of CPTs 7, 8, and 9 (2017) Site Class Estimator B-1 Liquefaction CPT-4 (2003) Liquefaction CPT-7 (2017) Liquefaction CPT-8 (2017) Liquefaction CPT-9 (2017) EARTH SYSTEMS SOUTHWEST Ij 1 ♦♦so � a •++ %fA U. tl . u �i ' - _ ': + d►. ., ♦tf e:Zis 1[, ee a•e•/39e•' `es n A. ' ., !. n ass i. a1 Yof a, er Y.e U. 41 11 . IY A'♦At #Q. n »ej Rl iZtl2J��.,i • f A♦f♦r•Y 11� tl II U a•a.t _ whh �.i6 t •y -.qa•1 ��. a 11, N .. t i II •4,• ��, ••,v� a°0s�»ei n II +�. I ni pp♦ os"aw 3 ; �� HrAiasa.aiy�:• .q n 11'.,- II 45' .��'.,�a.••.•a.?c e. -T- ., -,n t., .'. _,; -IP. -. � .. _ .., L.. _ -_� :.AYE.: 77 tl' e.Rr. r s« AVENUE �q n •• f ee♦s♦�. ►P. II":• A y V♦`•�.i •r�•a 1.'=w♦ A : I�i s il, m.+ • - .Z f�l _ .� sL• _ 14`a��:iaaio l�•giaiei is O'_ u••!a♦e <; _y •nl 1 air ,: .r_ta#1�.a♦v•4 '-i1 ap ♦♦�1 niii aiYr•l��a•f♦ jiT Uas-•sa JJI�{Flr ". t k t rll_.' .. • ip - - . • ►v�cSa•, •saY Ia,Yj'a'ii III: 0 ♦♦1 T cc' qr 3as ♦�5.....;• ,1 2n �� r aaa♦ai4+A •aree �� e o�c♦eY♦°* i"> il!. 'n� - ••iaeY}••i !saes♦d♦ EHa uAia r_ ..t • •io.•eJa• af••a •f e•q.1 as T-♦w a+'a•a a *'beAta• 11•:1♦+1 •' a�•s asvy �tr Ka•• .. 11- _ ee♦♦Rb faf4�afaY• t a♦f ••...• er•i ; aN A {•jn p ••i1 •a�ar •• It 3•w4 +A•h�If epN a••J •iae I+• -a erase again ' {,: � 11- .' lse•1�?{:af •fv e�t�@i•a•}:► 11♦•aR •Oa IS• o4 f.1N ♦••a °♦} 1DaRr• 4iYSCa iVVa+ �g �ele�a♦•11Y.iaee f e•s 11 iA IY 4♦;7 ay•ei•iA - a{rPa Reanl•Me ♦•yg6f •atle fit,,,, ' f,• '- 1 - � Q:ea,p <9Ra Reii k.., - - ,� V- � Q* - as ae•asi e•s aY•: - o (r u y. It 1 vs••A•a• 'Iaq. :n - I .'„-0 a U a ni lY aaaoA aaa•�p»• ,U. U a U�*. 11, ��1^.. i 'fara•4ee y' ',.t' U It,p +Its a � "'•Avenue . AveNUEavEruE e58 , q -. _ - d •uo•ead66 ra- �a3Tn"e�l y . : n 3 _ tr 77 s�r,o oavaenvar i. e. u 1{i �: ,�O i:• 0 �-� i, °ri °ua ii�iaK rii�; p Ae`�1,,1 avel; is �PJ t. 28 u I: 27 t ii°j eY A♦ a.• teff�o It o ltij 9 • sa aaaa•♦.•, • . .� _ \ 1. �- F 11 ,` y --v T / ,+ - ■ allSYa •1`. I _' R �. -1 z ' c..•.a V. ( -`- � 'Ti = ! a r ♦- r■i'Y° •■ 4 i= COunfyPa ;m it li i n �••..•.•r•.•v- ,.��' •sMsi11. ■� Y • is '�.'•��' - ,- 1 It,�1�0 �I /� 11"1l---..-•�+� �' �-. r'�/ Tia• Bounda srr•aa•wee:e ls--- u AOUE`DUCT - �-a3 ..r.��:�, i . ♦ ° p � e a ��a "••••'-- �'sP.IP� : .� .. -��j�•7 "1\•1 �, :... �v 2� u _'I'-'�'-�.,,.`Y---0 '.�.��_^"A �•ae• a ss Na•a• R.ffi s �� ... : a. o„ ra61r/�j' 2,S @\ VI ,n --.'.. s•^!• ��a% - !r ��1: ypas a O•e••♦f Oea lfa e ry +.f y-�.+.-„_.G° iYs.1•. �A,a �l li.+e Nb'a 0'ee t. O(! • 1lG-.' U vt ,11)a•�'^'"^^..:.z7-"—aasvry ►se aa4 uaopat- W •� I1/�•��\/t�{� a r 1 N ns •_.. , .A.e:.♦:.a82� 5h -OF ! / Z-�,, •••aa•• ar aasea •°yaaf '• � \\\\��-•1=—"%A1'•"�aa•aai:.rdoi.•aY ♦aa t4a '�11 „U 4t7, �- fYa.••aytlwiei as •• r ••♦ igp '" ariiswiJ�liya'si+�iit�� r` w+._/� ,. S {!Y', 'i --_� -.Iry x •.Yea.. 11 .G •.ae.a «,a .....,E^ "i•"' •�*' +^WaJ] aaooHiZ�a'az�♦ •°Ysae •s / ./ ( � t3'_ \ G� p �wi SA �aA:r ••��,, ii.r� �° ••-•--•A°1�aay.Y•a!• kYe ••teas' • .--,..--.• .... . / \ \ U��.. 'U��` L - eQr. Yfrr.�- Pu- �ii'•.�•�-Y�"•. + ai °ii•rrYaR:i as..� • i 1} y ��-?�� "j.. R'"�.a ri '� ,t:�-+,ysa.sa•aa+fai.•r vaa••e/ai• }••1•pY•aAaNap•aRYYaw e ;,. � j >�. \, '., OJ.rk. rl �� pu••1i as ••!♦Ra}.a seai ♦ ••.♦.•aa• .:1 �. "� .'^'�'--.-.�. °yw°Ysiia :n�a SSe tosv arrooere Yam. :..-. ' I' ) .. c , 1 •�� a �.; YIe_}1 Ra AAo i ♦ ¢ieirY:i ..• lam...• nUe`6O?'Ya��a•a wr.. R2a .Ess 76^ A:VEND T-- in _�1'� } a—�— — •-gin a:.. .. o—ao — . a�.-�r .._..__ s„1,�•,�..,---•-->l,.o,_,,, ��,.,.. ..�1 1 VA, r. o..• I�`'�=;,...p / �-• ; �• !.P r-"c [��' �c j�.s vv _' � ---- 4 . � t�-'S�`�"i )wr` \ ' '��S' 1 :".�-�}�e- '..�."t' ��': _.'tea~s.•Ra.1£,�•-,.,,, Lam' .�„'-.-.."'. 3W�rDQZ7QenPooiQ�. *^_ Mm Reference: USGS Topographic Map, Quadrangle, Indio; Calif. (1956), La Quinta 1982 Martinez Mtn Calit'.(1981); and .Valerie, Calif. (1956). + WilliFOR - �mm00000mo�lPdl�rd�,�'�� Op =fir c -PrPlate 2 Andalusia at Coral Mountain I' Test Location Map �•� pm��om QOaQ��9, ®��w��go�r��,�►�� i58588 Madison Street Q��M� �. DESCRIPTIVE SOIL CLASSIFICATION 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 loge are approximate only and may be transitional. SOIL GRAIN SIZE U.S. STANDARD SIEVE 12" 3" 3/4" 4 10 40 200 BOULDERS COBBLES GRAVEL SAND SILT CLAY COARSE FINE COARSE MEDIUM FINE 305 16.2 19.1 4.76 2.00 0.42 0.074 SOIL GRAIN SIZE IN MILLIMETERS 0.002 RELATIVE DENSITY OF GRANULAR SOILS (GRAVELS, SANDS, AND NON -PLASTIC SILTS) Very Loose 'N=0-4 RD=0-30 Easily push a 1/2-inch reinforcing rod by hand Loose N=5-10 RD■3050 Push a 1/2-inch reinforcing rod by hand Medium Dense N=11-30 RDa50-70 Easily drive a 1/2-inch reinforcing rod with hammer Dense N=31-50 RD=70-90 Drive a 1/24nch reinforcing rod 1 foot with difficulty by a hammer Very Dense N>50 RD=90-100 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 34nch 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 (%). CaUndrained shear strength (cohesion). CONSISTENCY OF COHESIVE SOILS (CLAY OR CLAYEY SOILS) Very Soft •N=0-1 'C=0-250 psf Squeezes between fingers Soft N=2.4 C=250-500 psf Easily molded by finger pressure Medium Stiff N=5-8 C=500-1000 psf Molded by strong finger pressure Stiff N=9-15 C■1000-2000 psf Dented by strong finger pressure Very Stiff N=16-30 C=2000-4000 psf Dented slightly by finger pressure Hard N>30 C>4000 Dented slightly by a pencil point or thumbnail MOISTURE DENSITY Moisture Condition: An observational term; dry, damp, moist, wet, saturated. Moisture Content: The weight of water in a sample divided by the weight of dry soil in the soil sample expressed as a percentage. Dry Density: The pounds of dry soil in a cubic foot MOISTURE CONDITION RELATIVE PROPORTIONS Dry ....................Absence of moisture, dusty, dry to the touch Trace ............. minor amount (<5%) Damp................Slight Indication of moisture with/some...... significant amount Moist.................Color change with short period of air exposure (granular soil) modifier/and... sufficient amount to Below optimum moisture content (cohesive soil) Influence material behavior Wet....................High degree of saturation by visual and touch (granular soil) (Typically >30%) Above optimum moisture content (cohesive soil) Saturated .......... Free surface water LOG KEY SYMBOLS PLASTICITY ' Bulk, Bag or Grab Sample DESCRIPTION FIELD TEST Nonplastic A 1/8 in. (3-mm) thread cannot be rolled Standard Penetration at any moisture content. 0 Split Spoon Sampler Low The thread can barely be rolled. (2" outside diameter) Medium The thread is easy to roll and not much time is required to reach the plastic limit ' Modified California Sampler High The thread can be rerolled several times (3" outside diameter) after reaching the plastic limit. a No Recovery GROUNDWATER LEVEL Water Level (measured or after drilling) Terms and Symbols Used on Boring Lo Water Level (during drilling) GRAPHIC LETTER MAJOR DIVISIONS SYMBOL SYMBOL TYPICAL DESCRIPTIONS •��'�'�� Well -graded gravels; gravel -sand' GH% mixtures, little- or no fines ' CLEAN GRAVELS r�r� r� r�r� �i ir•r�; r"r'.r"�''''' raded GRAVEL AND ••.••..•..•..•..••••.•. GP Poorl ravelsgravel-sand Y� gravels, GRAVELLY r;r�r;r;r;r;r;r�: r. r.•r• r• r•r• r• r• mixturos. Little or no fines , SOILS GM Silty gravels, gravel -sand -slit ' COARSE More than 50%0 of GRAVELS mixtures GRAINED SOILS coarse fraction WITH FINES retained on No. 4 sieve GC Clayey gravels, grave"and-clay mixtures SW Well -graded sands, gravelly sands SAND AND CLEAN SAND little or no fines SANDY SOILS (Little or no fines) SP Pooily-graded sands, gravelly More than 50% of k sands, little or no fines material is lamer i than No. 200 sieve size } < < SM Silty sands, sand -silt mixtures' SAND WITH FINE More than 50% of (appreciable ; coarse fraction amount of fines) passing No. 4 sieve SC . Clayey sands, sand -clay mixtures Inorganic slits and very tine sands, ML rock flour, silty low clayey fine sands or clayey silts with slight plasticity FINE-GRAINED LIQUID LIMIT LESS THAN SO CL Inorganic clays of low to medium plasticity, gravelly clays; sandy SOILS clays, silty clays,. lean clays OL Organic silts and organic silty claysof low plasticity P ity SILTS AND Inorganic silty, micaceous, or CLAYS MH diatomaceous.fine sand or silty Solis More than 50% of ol material Is smaller LIQUID LIMIT CH Inorganic clays of high plasticity, than No. 200 GREATER fat clays • sieve size THAN 50 ririrrrirrrr - OH Organic clays of medium to'high • rrriirriro plasticity, organic silts HIGHLY ORGANIC SOILS rraxrr.rxnrr yaayayyyyay a xraaa rYa r r pT Peat, humus, swamp soils with, araxrrrraara .high organic contents .rrayarrrraa VARIOUS SOILS AND MAN MADE MATERIALS Fill Materials MAN MADE MATERIALS Asphalt and concrete Soil Classification System Earth Systems Southwest 'Earth Systems 'Southwest W LU CPT No: CPT-4 "CPT Vendor; Holguin"Fahan & Associates , Project Name: Coral Mountain "Truck Mounted Electric Project No.: ,0305-01 ,Cone with 23=ton rea_ ction_ Location: See Site. Exploration Plan Date: 4/1 5 t)03 d W p Friction Ratio(%) Tip Resistance, Qc(tsQ Graphic Log (SBT) Inteipreted Soil Stratigraphy 8 6 4 2 0 40 80 120' 160 200 `240 0 12 Robertson & Campanella ('89).Density/Consistency verconso I ate , Soil very dense Clayey Silt to Silty Clay very stiff Sandy Silt to Clayey Silt loose Sandy Silt to Clayey Silt very loose Clayey Silt to Silty Clay very stiff Sandy Silt to Clayey Silt dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt dense Clayey Silt to Silty Clay hard Silty Clay to Clay very stiff Clay firm ' Clay firm Silty Sand lay to Clay hard very dense Sandy Silt to Clayey Silt dense Sandy Silt to Clayey Silt medium dense Clay very stiff Clay very stiff Silty Clay to Clay very stiff Sandy Silt'to Clayey Silt very loose Silty Sand to Sandy Silt medium dense Sandy Silt to Clayey Silt medium dense Sandy Silt to Clayey Silt medium dense Silty Sand to Sandy Silt dense Silty,Sand to'Sandy Silt very dense Silty Sand to Sandy Silt very dense Silty Sand to Sandy Silt medium dense Silty Sand to Sandy Silt dense ' Clayey Silt to Silty Clay hard Clay very stiff Silty Clay to Clay very stiff. Sand to Silty Sand medium dense Silty Sand to Sandy Silt medium dense Sand to Silty Sand medium dense Sand to Silty Sand medium dense Silty Sand to Sandy Silt medium dense Clayey Silt to Silty Clay hard Clay very stiff Clay very stiff Silty Clay to Clay stiff Silty Clay to Clay stiff Silty Clay to Clay stiff Clay Clay to Clay stiff y very stiff Overconsolidated Soil medium dense Sand to Clayey Sand dense Silty Sand to Sandy Silt .dense: Silty Sand to Sandy Silt dense -End of Sounding @ 50.9 feet u ti x' _ 5 - _ 10 15 _ 20 25 _ _ 30 , milli& 35 _ _ 40 45 50 9 AVE, Kehoe Testing and Engineering r 714-901-7270' rich@kehoetesting.com = www.kehoe-testing.com Project: Earth Systems Southwest/Andalusia Location: Madison St & S8th St La Quinta, CA `- Cone resistance qt Sleeve friction Pore pressure u Friction ratio 0 t i t F . i 3 _ dC s 10 is 20 2s 30 .. 35 .40 CL 0- •45 s0 ss 60 65 ' 70 75 _ 80 0 100 200 300 400 500 0 s 10 15 2U 25 30 s .. 35 40 !Z 45 50 5s 60 65 70 75 so t � i I 1I 1 I i _ I l 1 ! I jt � r i . 't- t -15 -10 -5 0 5 10 ' s 10 is 20 2s 30 .-.' 35 L 40 a at " 0 45 s0 ss 60 65 70 75 80 Tip resistance (tsf) Friction (tsf) Pressure (psi) : Rf (%) CPeT-rr v.2.0.1.55 -CM data presentation & interpretation software - Report created on: 4/21/2017, 8:41:04 AM Project file: C:\EarthSysLaQulnta4-17\Plot Data\Plots.cpt CPT-7 Total depth: 80.08 ft, Date: 4/17/2017 Cone Type: Vertek `Sand & silty sand , 'SSilM s hd & sandy silt Sand', silly sand _ 15 t ;Silty sand & sandy silt 10 - - �Shclysand:&sandy-.silt._- S and &' sit ty sand sarid &seedy silt_^ j i t i i +Sand & sitty.sand 20- _ . Silly sand & sandy sill - Clay j .Sand &silty sand a a,Silly sand & sandy silt• 30�_� sand & sar>dy j{sili'" 3CCIly 35-;Ia�y 3 CCCclaabyyy t & silly Clay'. 40•, � s"""'"'Sand'& s'ily sari!"t'�"", - ! Silly sand & sandy, 'silt • r ' Silty sand& sandy silt'"' 50 CIaY -' ,.Sand& +Illy � ss Sand ;Sand & silty sand,' 55.:t. .� s ' "S�dR•silly Saul rSand ro Sand& -silly sand i- ; sand Silty & sandy silt 57 Silty send & sandy silt' sand &sandy silt, FSilly �lartd&illy sand 30 ' 0• :2 '41' �6, 8. 10 12' 14 lfi. 118: SU06bertson, '2010) 0 L KV Kehoe Testing and Engineering , 714-901-7270rich@kehoetesting.com www.kehoetesting.com Project: Earth Systems Southwest/Andalusia Location: Madison St & 58th St La Quints, CA CPT-8 Total depth: 60.18 ft; Date: 4/17/2017 Cone Type: Vertek Cone resistance qt Sleeve friction Pore pressure u Friction ratio Soil Behaviour Type I t ` t � i 1 •� i 1 1 3-i -- - ri r. .._...._..-.- - 5 10 15 20 25 30 .-. 35 L 40 v 4s so ss 60 65 70 75 80 0 100 200 300 400 500 0 2 4 6 8 -15 -10 -5 0 - 5 . 10 5- 10- is 20 25 30 .. 35 40 a a, 0 45 50 55 60 65 70 7s 80 t r- i � t 6 1 i i • 5 10 15 20 25 30 35 40 a 0 45 so 55 60 65 70 7s 80 I I i I t I ` I I -T. f I r Tip resistance (tsf) Friction (tsf)- Pressure (psi) Rf (%) .SBT+(R6bertson;'2010) CPeT-IT v.2.0.1:55 - CPTU data presentation & interpretation software - Report created on: 4/21/2017, 8:41:29 AM 0 Project file: C:\EarthSysLaQuinta4-17\Plot Data\Plots.cpt A Kehoe Testing and Engineering ' 714-901-7270 -. • _ rich@kehoetesting.com www.kehoetesting.com CPT-9 Project: Earth Systems Southwest/Andalusia Total depth: 60.12 It, Date: 4/17/2617 Location: Madison St & SSth St La Quinta, CA ; , Cone Type: Vertek Cone resistance qt Sleeve friction. Pore pressure u Friction ratio 'Soil Behaviour Type' 5 10• 15 20 25 30 35 40 45 s0 55 60 65 7U 75 60 i ✓ i f jI 1 l ( i f i f 1 i � t s• 10 20 2s 30 35 -40 a 0 45 ry 50 ss 60 65 70 7s BO { - 7 � L i t 1 1 I t ! l I I • 5 10 is 20 2s 30 .. 35 a, 40 45 s0 55 60 65 7U 7s eo I ! � i l t I — 1 I � I l � 1 t i I 5 10 is 20 2s 30 35 i y 40 t]. p45 • 50 55 60 65 70 75 en — i -- , ,--- 5 ., 10'' .20 ss 30 3; , ' 40 �• r m 6 45 ' 50{ s 55 601 7s- ,An • •''Sand'&.silty sand' r ^Sand&.silty sand +� i r�_J J. , S and & sit sand I Silly sand& sandy silt, j S and & silly sand ^Silty sand`& sandy`sdt---{ 7 Sand &silly. sand +- Sllty sand& sandy silt - "Sand & silt' sand ISand & silly sand #�-} 'SSd ss�rd ,sa sdf - Sa�d & silly sand j 7Silty sand& sandy silt , :Sand& 1 silty sand -j :Silly sand & sandy silt ! r` 5ily sand&`sandy �Ia�y Sand&silty-sand---- ElkClE$ sand& sandy silt: -- t t Clay & silty clay— 'Silty �' �t sand $& sandy silt Sand.&-sily sardt- r , i, S i jSand & sily. sand J. Sdy sand & saridysilt_� I 0 100 • 200 300 400 500 - 0 2 4 6 � 8 • -15 -10 -s 0 s 10 0 • 2 4 6 8 0 ; 2 41 ',fi • 8.,i 10 12 �14. • 16 � 18. Tip resistance (tsf) Friction (tsf) Pressure (psi)- Rf (%)`- :SBTa(Robertsoft; `20"10) CPeT-rr v.2.0.1.55 - CPTU data presentation & interpretation softwareReport created on: 4/21/2017, 8:41:43 AM 0 Project file: C:\EarthSysLaQuinta4-17\Plot Data\Plots.cpt 111oring No. 1- 8-6 2003 Project and Number to 20 feet and - 8-13 2012 from • 20 ft to 60 feet' ESSW Field Staff Drilling Company CalPac Drilling Method 8"HSA Site Latitude (North) DeqE!;5 Minutes Seconds jDachnal d 0.0000 • Site Longitude (West). Degrees IMInutes _Seconds Decimal deg. 0.0000 ` Data Drilled - Ave. SPT N-value blowaHt) 14 - _ Hamner Weight Iba Ave. Shear Wave Veloci Posec ^ ' • 140 731 (Upper 60 feet) ,. Hammer Drop (inches Ave. Friction An !! (degjjs + - ' - 30 131 - • - - Energy- - Soil Profile T e Slta CLnas - 68 y ' D.. - • Borehole Correct lon Cb • Estimated Shear Wave Velocity •• 1 - Based on Depth Less than 1001tn/..•) v •m,ueeumaewi Hou.. 1- 761 (Upper 100 feet) - Depth (k) "Blow : Count Type of Sampler d. fee - - Npp blows NONE blowslk V,i.. misec . V•, ftlsec • 43i • d rears d�Nppi d#Al,i • d,f4q Consistency I1 Coarse Grained Consistency Fine Grained 2.5 36 s 2.5 36.72 40.80 294.62 966.34 36.04 0.06127 0.00259 0.069358 - Dense Hard 5.0 • 36 :.s 2.5 36.72 40.80 294.62 966.34 36.04 0.06127 0.00259 0.069358 - .Dense - Hard 8.0 ' 24 c 3.0 13.67, 18.22 233.21 764.94 31.82 0.16462 0.00392 0.094286 Medium Dense Stiff . -"10.0 24 c 2.0 13.67 -18.22 233.21 764.94. 31.82 0.10975 0.00261 0.062857 Medium Dense 1Stiff 12.5 30 c 2.5' 19.36 22.78. 248.80 816.08 • 32.89 . 0.10975 0.00306 0.076003 Medium Dense VeryStiff 20.0 24 c 7.5 17.31 18.22 233.21 764.94 32.82 0.41155 0.00980 0.235714 Medium Dense VeryStiff 25.0 12 s 5.0 15.50 13.60 214.24 702.69 30.51 0.36765 0.D0712 0.163897 Medium Dense Very Stiff . 30.0 20 c 5.0 15.19 15.19 222.20 725.54 • 30.99 0.32924 0.00689 0.16135 Medium Dense Very Stiff 35.0 9 s - -5.0- 12.24 10.20. 197.09 646.45 29.32 0.49020 0.D0773 0.170S34 Medium Dense Stiff 40.0 25 c 5.0 18.98 - 18.98 235.99 774.05 32.01 0.26339 0.00646 0.156201 Medium Dense Very Stiff - 45.0 11 s 5.0- - •. 14.96 12.47- 208.90 685.18 30.14 - 0.40107 0.00730 0.165906 Medium Dense Stiff 50.0 6- c - 5.0 4.56 4.56 156.01 521.72 -26.47 - 1.09745 0.00977 0.188897 Loose r Firm • `= 55.0 1S s 5.0 - 20.40 17.00 228.56 749.67 31.50 0.29412 0.00667 0.158746 Medium Dense Very Stiff 60.0 .. 28 s 5.0 38.08 - 31.73- 273.91 898.42 34.62 0.15756 0.00557 0.144417 Dense Hard * [Sampler Liner Correction Cs it Profile Type Site Class " • - Total: - 60.0 - _ Total: _+ 4.31888 0.08208 1.917524 • - + i 1.2 Applied i15PT Sampler Used D - - + - , ^ • • - _ , ' . . a - 1.0 Applied VCal Sampler Used r •'Caltrans.Geotechnital Services Design Manual, Version 1.0, August 2009 x i _ �• �•^ 'ti . • .. - - - - ` - eoan4•a. •'"°'r+w ua"eemura'o•uc'ro.a using NGOHE corrected only for Hammer Energy - ' - . - Rod Len Above Oreund k '� v.,re• • ' F - , r e - 1 " 3 - °m�O1•® w'U Y1°r'lo'� 100 - Consistency classifitation basedupon ASCE 1996tl - - - a.o:q . - are nmoui .Iro . - - ♦ • Ee Fsti th to rate Vs Over s -On'�. `�} _ ry • - • .' m rr s M k Spreadsheet Version 2.2.1, 2011: Prepared by Kevin L Paul, PE, GE •Caltrans Estimation Method _ c Sri • •,ten *♦ ~ 1. • -. .. - r V + eft a .. ) � r • � .... y - . .- _ _ •- e Dan. Nulametk. r dp Donul•Enmarnllb(ekmnplm,1940) .H.- Earth Systems - EVALUATION, OF LIQUEFACTION POTENTIAL AND INDUCED GROUND SUBSIDENCE Andalusia Project No: 0930641 Method Used:01 1998 NCEER (Robertson & Wride) Ground Compaction Remediated to depth of: NA feet Settlement Analysis using Tokimatsu & Seed (1987) using clean sand Qc1 n/NI(60) ratio =5 Plol v0�-- Limiting Ic: Sounding: CPT4 2003 Earthquake Magnitude: 8.2 PGA, g: 0.54 Calc GWT (feet): 13.2 Qc1n/N1(60):F5____J' r_1_4.' F-2.6 Cyclic Stress Ratio Factor of Safety T Volumetric Strain Total Sub�sidence (in.) Tip Resistance, Oc (tsf) a. Qc1n Total' 0.0 0.5 1.0 1.5 2.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 - 0 so 100 150 , 2 3 250 0.0 0.2 0.4 0.6 0.8 1 -0 .0 4.0 ' 5.0 6.0 7.0 8.0 250 1.0 3.5 41 _..1.07. � 1 3 1.5 2.01C2.5 3.0 0 0 10 10 20 20 4) 30 30 40 40' 50 so 10 20' 30 40 50 U 10 20 30- 40 50 �Q0cC inn -clean sandR -CRRIFS Pro WDense Qc1n CEO 80.nd.L] Total Thickness of Liquefiable Layers: 7.9 feet Estimated Total Ground Subsidence (Settlement): 1.3 Inches T, 10, 210 30 40 50 17- avg increment =0.10m Ignore 1 st/last increment into sand/silt soils: Sounding: CPT4 2003 Earth Systems - EVALUATION OF LIQUEFACTION POTENTIAL AND INDUCED GROUND SUBSIDENCE Andalusia Project No: 09305-31 Method Used: 1998 NCEER (Robertson & Wride) Use which FC adjustment: [_ ] Based on Clean Sand Qc1 n Use which Apparent FC Curve: Robertson Lower Bound Plot Farthnuaka Mannituda- 92 PGA. n- 0.6d 7 Fines Factor, Kc KN Aqcn (Moss) 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 0 10 20 30 40 50 0 0 .....,....., 0 r-- r-� 10 20 30 40 so �NCEER Moss (eHecbve 20 F 1 120 30 1 1 I 130 40140 ===■o IOIIO ��il� 1gill Ik I�ii �I�1■ ri �111 F011111 ill ; `111 �l�il 0l�m 1l�il■ Irk i lin flI [� lispi MEN IRr _ Earth Systems - EVALUATION OF LIQUEFACTION POTENTIAL AND INDUCED GROUND SUBSIDENCE Andalusia Project No: 09306-31 Method Used:1998 NCEEK(Robert son S Wride) Ground Compaction Remediated to depth of: NA feet Settlement Analysis using Tokimatsu & Seed (1987) using clean sand Qcln/N1(60) ratio =5 PIo1 r Limiting Ic: Sounding: CPT-8 Earthquake Magnitude: 8.2 PGA, g: 0.64 Calc GWT (feet): • 13.0 Qc1n/N1l(6005----7 r1 - r2.6 r 1�1 �� lily � C• ��■ Mini IRS �I� -'Il■ ail �wii Finn Yoi_ ii ��.01n .. - lean send Total Thickness of Liquefiable Layers: 22.0 feet Estimated Total Ground Subsidence (Settlement): 4.0 Inches l� avg increment =0.10m Ignore 1 st/last increment into sand/silt soils: Sounding: CPT-8 Earth Systems - EVALUATION OF LIQUEFACTION POTENTIAL AND INDUCED GROUND SUBSIDENCE Andalusia Project No: 09305-31 Method Used: 1998 NCEER (Robertson & Wride) Use which FC adjustment: Based on Clean Sand Qc1 n Use which Apparent FC Curve: Robertson Lower Bound Plot Earthnuaka Mannifudar A PrAA. n• n Ad 7 Fines Factor, Kc KA Aqcn (Moss) 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 0 10 20 30 40 50 0 0 .....,.,.,, 0 - r- r� 10 20 s 0 30 40 50 �NCEER Moss (effective) 20 C i I 120 30 1 1 I 130 40 t----I140 011 K I I MA rdi HE villill Irlllll -��ilt, ?4 Earth Systems - EVALUATION OF LIQUEFACTION POTENTIAL AND INDUCED GROUND SUBSIDENCE Andalusia Project No: 09306-31 Method Used: ©1 1998 NCEER (Robertson & Wride) AL' Ground Compaction Remediated to depth of: NA feet Settlement Analysis using.Tokimatsu & Seed (1987) using clean sand Qc1n/N1(60) ratio =5 Ploi 'W Limiting Ic: Snundinn- CPT.9 Farfhnualra M—nit.dw• R 9 PLSA n• n 6A Cale r:WT if-0- y3 n, n,1mKjvam•15------1 r 7 L i-9 R9i �i 0xis MIN MENEM �III� �I Itil� ■Lil� �� ■rr�,�� #I' mm nn Wn 1 ��!r� ,.MINI ,ono �:► �II"NoIllo �C'�QC NIII 'LINENS IBA 1■■1 (ftld) Total Thickness of Liquefiable Layers: 29.5 test 3 Estimated Total Ground Subsidence (Settlement): 5.3 Inches Earth Systems - EVALUATION OF LIQUEFACTION POTENTIAL AND INDUCED GROUND SUBSIDENCE 3©avg increment =0.10m Andalusia Project No: 09305-31 Method Used: 1998 NCEER (Robertson & Wride) • 4 Ignore lstflast increment into sand/siltsoils: Use which FC adjustment: = Based on Clean Sand Qc1 n Use which Apparent FC Curve: Robertson Lower Bound, Plot -Sounding: CPT-9 Earth uake Magnitude:. 8.2 PGA, g: 0.64 7 stress exponent, n Friction Ratio, Rf Tip Resistance, Qc (tsf) Qc/N Ratio N1(60) s 0 10 20 30 40 50 0 0 0 2 0 4 O B 0 8 1 0 8 7 8 5 4 3 2 1 0 0. 50 100 150 200 250 300 350 400 + j 2 3 4 5 6 7 8 0' 10 20 30 40 50 80 70 ` 30 to 1�1 0 10 20 n 0 30 40 50 i i 30 40 nn9 140 f Earth Systems - EVALUATION OF LIQUEFACTION POTENTIAL AND INDUCED GROUND SUBSIDENCE Andalusia Project No: 0930"1 Method Used: 1998 NCEER (Robertson & Wride) rmund Cmmnnrfinn Remediafed to denfh of, N�- Alfeat Settlement Analvsis usinn Tnkimatsu & Seed 119R71 usinn clean sand Oc1n/N1(601 ratio =5 Plo1 ;1I Limiting Ic: Sounding: CPT-7 Earthquake Magnitudei 8.2 PGA, g: 0.54 Calc GWT (feet): 16.0 Qc1 n/N1 (60): 111�� mope semi '.' C lil IIIII �NINE IIYIINN 0 NOR !F� iiilil lilll in�� w r rill �1 �Wll�i i�i I I on I �Mn �mn nil i °- Total Thickness of Liquefiable Layers: 22.0 feet Estimated Total Ground Subsidence (Settlement):.3.3 Inches ' Earth Systems - EVALUATION OF LIQUEFACTION POTENTIAL AND INDUCED GROUND SUBSIDENCE avg increment =0.10m Andalusia Project No: 09305-31 Method Used: 1998 NCEER (Robertson & Wride) Ignore 1st/last increment into sand/silt soils: LU Use which FC adjustment: Based on Clean Sand Qc1 n Use which Apparent FC Curve: L_.�_ J Robertson Lower Bound Sounding: CPT-7 Earth uake 1.0 0 10 20 a 0 30 40 50 Fines 1.5 2.0 Factor, 2.5 Kc 3.0 1.0 0 10 20 30 40 so 1.5 K, 2.0 0 0 10 20 30 40 50 Aqcn 10 20 (Moss) 30 40 50 �NCEER Moss (eRedwe Magnitude: 8.2 PGA. a: 0.54 Plot 7 SIR HC I Ilion �� INS`I ��I m�� 5-11111