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HomeMy WebLinkAboutCDP 2019-0009; AKIN RESIDENCE; REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION; 2019-07-03REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION Akin Residence 5290 Carlsbad Boulevard Carlsbad, California JOB NO. 19-12322 03 July 2019 Prepared for: Sadri and Rose Akin RE.Cr:IVED JUL I ! 2019 Cl ry C)F C1\f-<LSBAD PLA(\Jl\l;I\J(~ DIVISION - 4r.-4&U Geotechnical Exploration, Inc. SOIL AND FOUNDATION ENGINEERING • GROUNDWATER • ENGINEERING GEOLOGY 03 July 2019 Sadri and Rose Akin 8839 San· Badger Way Elk Grove, CA 95624 Job No. 19-12322 Subject: Report of Preliminary Geotechnical Investigation Akin Residence 5290 Carlsbad Boulevard Carlsbad, California Dear Mr. & Mrs. Akin: In accordance with your request, and our proposal of March 28, 2019, Geotechnical Exploration, Inc. has performed a preliminary geotechnical investigation for the subject property. The field work was performed on May 30, 2019. In our opinion, if the conclusions and recommendations presented in this report are implemented during site preparation and construction, the site will be suited for the proposed residential project and associated improvements. This opportunity to be of service is sincerely appreciated. Should you have any questions concerning the following report, please do not hesitate to contact us. Reference to our Job No. 19-12322 will expedite a response to your inquiries. Respectfully submitted, GEOTECHNICAL EXPLORATION, INC. C:::: ~ = J ning Jaime A. Cerros, P.E. P. .G. 2615 R.C.E. 34422/G.E. 2007 Senior Geotechnical Engineer 7420 TRADE STREIT• SAN DIEGO, CA. 92121 • (858) 549-7222 e FAX: (858) 549-1604 • EMAIL: geotech@gei-sd;com - TABLE OF CONTENTS I. PROJECT SUMMARY ............................................................................................ 4 II. SCOPE OF WORK ................................................................................................ 4 III. SITE DESCRIPTION ............................................................................................. 5 IV. FIELD INVESTIGATION ........................................................................................ 5 V. LABORATORY TESTS & SOIL INFORMATION ........................................................... 6 VI. REGIONAL GEOLOGIC DESCRIPTION ..................................................................... 8 VII. SITE-SPECIFIC SOIL & GEOLOGIC DESCRIPTION .................................................. 13 A. Stratigraphy ............................................................................................ 13 B. Structure ................................................................................................ 14 C. Limitations .............................................................................................. 14 VIII. GEOLOGIC HAZARDS ........................................................................................ 14 A. Local and Regional Faults .......................................................................... 15 B. Other Geologic Hazards ............................................................................ 19 C. Geologic Hazards Summary ....................................................................... 21 IX. GROUNDWATER ............................................................................................... 22 X. CONCLUSIONS AND RECOMMENDATIONS ............................................................ 23 A. Preparation of Soils for Site Development ................................................... 24 B. Design Parameters for Proposed Foundations .............................................. 27 C. Concrete Slab On-Grade Criteria ................................................................ 31 D. Site Drainage Considerations ..................................................................... 36 E. General Recommendations ........................................................................ 37 XI. GRADING NOTES .............................................................................................. 38 XII. LIMITATIONS ................................................................................................... 39 FIGURES I. II. IIIa-d. IV. Vicinity Map Plot Plan Exploratory Excavation Logs Geologic Map and Legend APPENDICES A. Unified Soil Classification System ------.. ----... - - --- - -... - - - - - -- REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION Akin Residence 5290 Carlsbad Boulevard Carlsbad, California JOB NO. 19-12322 The following report presents the findings and recommendations of Geotechnica/ Exploration, Inc. for the subject project. I. PROJECT SUMMARY It is our understanding, based on communications with you, that the existing two- story, single-family residential structure will be removed, and the site will be developed to receive a new two-story, single-family residence with attached two-car garage and associated improvements. The proposed residential structure is to be constructed of standard-type building materials utilizing a conventional foundation system. Final construction plans have not been provided to us during the preparation of this report, however, when completed they should be made available for our review. Additional or modified recommendations will be provided at that time if warranted. II. SCOPE OF WORK The scope of work performed for this investigation included a site reconnaissance and subsurface exploration program, laboratory testing, geotechnical engineering analysis of the field and laboratory data, and the preparation of this report. The data obtained and the analyses performed were for the purpose of providing design and construction criteria for the project earthwork, building foundations, and slab on- grade floors. Akin Residence Carlsbad, California III. SITE DESCRIPTION Job No. 19-12322 Page 5 The property is known as Assessor's Parcel No. 210-063-09-00, Lot 42 of Terramar Unit No. 1, per Recorded Map 2696, in the City of Carlsbad, County of San Diego, State of California. Refer to Figure No. I, the Vicinity Map, for the site location. The site located at 5290 Carlsbad Boulevard consists of approximately 0.16 acres. The lot is located on the east side of Carlsbad Boulevard, in the City of Carlsbad. The property is bordered on the north, east and south at approximately the same elevation by similar residential properties; and on the west at approximately the same elevation by Carlsbad Boulevard. In general, the lot slopes very gently to the west. Refer to Figure No. II, Plot Plan. The existing structure on the property consists of a two-story single-family residence with attached two-car garage and associated improvements. Vegetation on the site primarily consists of ornamental landscaping including trees and decorative shrubbery. The building pad is relatively level at an approximate elevation of 57 feet above mean sea level (MSL). Elevations across the property range from approximately 56 feet above MSL along the west property line to approximately 59 feet above MSL in the northeast corner of the property. IV. FIELD INVESTIGATION The field investigation consisted of a surface reconnaissance and a subsurface exploration program utilizing hand tools to investigate and sample the subsurface soils. Four exploratory excavations were advanced across the lot in the vicinity of - - - -.... - - - - ------- ----- --- - -----------.. --.. ---- -... - - ... -.,, - -.... -----..,_ Akin Residence Carlsbad, California Job No. 19-12322 Page 6 the proposed structure. The exploratory excavations were advanced to a maximum depth of 5 feet, in order to obtain representative soil samples and to define the soil profile across the project area. The soils encountered in the exploratory excavations were continuously logged in the field by our geologist and described in accordance with the Unified Soil Classification System (refer to Appendix A). The approximate locations of the exploratory excavations are shown on the Plot Plan, Figure No. II . Representative samples were obtained from the exploratory excavations at selected depths appropriate to the investigation. All samples were returned to our laboratory for evaluation and testing. Exploratory excavation logs were prepared on the basis of our observations and laboratory test results. Logs of the exploratory excavations are attached as Figure Nos. IIIa-d. V. LABORATORY TESTS & SOIL INFORMATION Laboratory tests were performed on the retrieved soil samples in order to evaluate their index, strength, expansion, and compressibility properties. The test results are presented on Figures Nos. IIIa-d. The following tests were conducted on representative soil samples: 1. 2. 3 . 4. 5. 6. 7. Moisture Content (ASTM D2216-10) Density Measurements (ASTM D2937) Determination of Percentage of Particles Smaller than #200 Sieve (ASTM D1140-14) Laboratory Compaction Characteristics (ASTM D1557-12) Expansion Index (ASTM D4829-11) Water Soluble Sulfate (504), Turbidity Method, California Test 417 Water Soluble Chloride (Cl), Titration Method, California Test 422 Akin Residence Carlsbad, California Job No. 19-12322 Page 7 Moisture content measurements were performed to establish the in situ moisture of samples retrieved from the exploratory excavations. Moisture content and density measurements were performed by ASTM methods 02216 and 02937. These density tests help to establish the in situ moisture and density of samples retrieved from the exploratory excavations. The particle size smaller than a No. 200 sieve analysis (ASTM O1140)aid in classifying the tested soils in accordance with the Unified Soil Classification System and provide qualitative information related to engineering characteristics such as expansion potential, permeability, and shear strength. Laboratory compaction tests (ASTM 01557) establish the laboratory maximum dry density and optimum moisture content of the tested soils and are also used to aid in evaluating the strength characteristics of the soils. The expansion potential of soils is determined, when necessary, utilizing the Standard Test Method for Expansion Index of Soils (ASTM 04829). In accordance with the same Standard (Table 5.3), potentially expansive soils are classified as follows: EXPANSION INDEX POTENTIAL EXPANSION Oto 20 Very low 21 to 50 Low 51 to 90 Medium 91 to 130 High Above 130 Very high Based on the laboratory test results, the sampled formational soils on-site have a very low potential expansion, with a measured expansion index of 1. Based on the particle size test results and our experience with the encountered soils, it is our - - ---... - ---- - ----... ------ - - -.... - --- -.... ---- -- Akin Residence Carlsbad, California Job No. 19-12322 Page 8 opinion that the on-site fill and formational soils in general possess a very low to low expansion potential. Laboratory testing of a representative sample of near surface soil indicates that the formational soil at the site has low concentrations of soluble sulfates and soluble chlorides. The pH is considered neutral (non-corrosive), and the concrete requirements for on-site soils is classified as SO exposure, no special requirements. Refer to the table presented below for laboratory test results. Sample Location HP-1 pH 7.2 Soluble Sulfates S04 % 0.002 Soluble Chlorides Cl % 0.002 Soluble Sulfates 20 Soluble Chlorides Cl m 20 -Based on the field and laboratory test data, our observations of the primary soil types on the project, and our previous experience with laboratory testing of similar soils, -..... -..... - - ---- -.... ----- our Geotechnical Engineer has assigned values for friction angle, coefficient of friction, and cohesion for those soils which will provide significant lateral support or load bearing functions on the project. These values have been utilized in determining the recommended bearing value as well as active and passive earth pressure design criteria for foundations. VI. REGIONAL GEOLOGIC DESCRIPTION San Diego County has been divided into three major geomorphic provinces: the Coastal Plain, the Peninsular Ranges and the Salton Trough. The Coastal Plain exists west of the Peninsular Ranges. The Salton Trough is east of the Peninsular Ranges. These divisions are the result of the basic geologic distinctions between the areas. Mesozoic metavolcanic, metasedimentary and plutonic rocks predominate in the Akin Residence Carlsbad, California Job No. 19-12322 Page 9 Peninsular Ranges with primarily Cenozoic sedimentary rocks to the west and east of this central mountain range (Demere, 1997). In the Coastal Plain region, where the subject property is located, the "basement" consists of Mesozoic crystallin_e rocks. Basement rocks are also exposed as high relief areas ( e.g., Black Mountain northeast of the subject property and Cowles Mountain near the San Carlos area of San Diego). Younger Cretaceous and Tertiary sediments lap up against these older features. These sediments form a "layer cake" sequence of marine and non-marine sedimentary rock units, with some formations up to 140 million years old. Faulting related to the La Nacion and Rose Canyon Fault zones has broken up this sequence into a number of distinct fault blocks in the southwestern part of the county. Northwestern portions of the county are relatively undeformed by faulting (Demere, 1997). The Peninsular Ranges form the granitic spine of San Diego County. These rocks are primarily plutonic, forming at depth beneath the earth's crust 140 to 90 million years ago as the result of the subduction of an oceanic crustal plate beneath the North American continent. These rocks formed the much larger Southern California batholith. Metamorphism associated with the intrusion of these great granitic masses affected the much older sediments that existed near the surface over that period of time. These metasedimentary rocks remain as roof pendants of marble, schist, slate, quartzite and gneiss throughout the Peninsular Ranges. Locally, Miocene-age volcanic rocks and flows have also accumulated within these mountains (e.g., Jacumba Valley). Regional tectonic forces and erosion over time have uplifted and unroofed these granitic rocks to expose them at the surface (Demere, 1997). - - - - --- - - - - ------- - """' - - -.. --- --------------.. ----... - ----------.. ..... Akin Residence Carlsbad, California Job No. 19-12322 Page 10 The Salton Trough is the northerly extension of the Gulf of California. This zone is undergoing active deformation related to faulting along the Elsinore and San Jacinto Fault Zones, which are part of the major regional tectonic feature in the southwestern portion of California, the San Andreas Fault Zone. Translational movement along these fault zones has resulted in crustal rifting and subsidence. The Salton Trough, also referred to as the Colorado Desert, has been filled with sediments to depth of approximately 5 miles since the movement began in the early Miocene, 24 million years ago. The source of these sediments has been the local mountains as well as the ancestral and modern Colorado River (Demere, 1997). As indicated previously, the San Diego area is part of a seismically active region of California. It is on the eastern boundary of the Southern California Continental Borderland, part of the Peninsular Ranges Geomorphic Province. This region is part of a broad tectonic boundary between the North American and Pacific Plates. The actual plate boundary is characterized by a complex system of active, major, right- lateral strike-slip faults, trending northwest/southeast. This fault system extends eastward to the San Andreas Fault (approximately 70 miles from San Diego) and westward to the San Clemente Fault (approximately 50 miles off-shore from San Diego) (Berger and Schug, 1991). In California, major earthquakes can generally be correlated with movement on active faults. As defined by the California Division of Mines and Geology (Hart, E.W., 1980), an "active" fault is one that has had ground surface displacement within Holocene time (about the last 11,000 years). Additionally, faults along which major historical earthquakes have occurred (about the last 210 years in California) are also considered to be active (Association of Engineering Geologist, 1973). The California Division of Mines and Geology (now the California Geological Survey) defines a Akin Residence Carlsbad, California Job No. 19-12322 Page 11 "potentially active" fault as one that has had ground surface displacement during Quaternary time, that is, between 11,000 and 1.6 million years (Hart, E.W., 1980). During recent history, prior to April 2010, the San Diego County area has been relatively quiet seismically. No fault ruptures or major earthquakes had been experienced in historic time within the greater San Diego area. Since earthquakes have been recorded by instruments (since the 1930s), the San Diego area has experienced scattered seismic events with Richter magnitudes generally less than M4.0. During June 1985, a series of small earthquakes occurred beneath San Diego Bay, three of which were recorded at M4.0 to M4.2. In addition, the Oceanside earthquake of July 13, 1986, located approximately 26 miles offshore of the City of Oceanside, had a magnitude of M5.3 (Hauksson and Jones, 1988). On June 15, 2004, a M5.3 earthquake occurred approximately 45 miles southwest of downtown San Diego (26 miles west of Rosarito, Mexico). Although this earthquake was widely felt, no significant damage was reported. Another widely felt earthquake on a distant southern California fault was a MS.4 event that took place on July 29, 2008, west-southwest of the Chino Hills area of Riverside County. Several earthquakes ranging from MS.Oto M6.0 occurred in northern Baja California, centered in the Gulf of California on August 3, 2009. These were felt in San Diego but no injuries or damage was reported. A M5.8 earthquake followed by a M4.9 aftershock occurred on December 30, 2009, centered about 20 miles south of the Mexican border city of Mexicali. These were also felt in San Diego, swaying high-rise buildings, but again no significant damage or injuries were reported. On April 4, 2010, a large earthquake occurred in Baja California, Mexico. It was widely felt throughout the southwest including Phoenix, Arizona and San Diego in - - - ....... - , .... ----- - - - - --.. -.. -.... - - ... ---- --------.. -.... .. ----· - - - - ---.... .. Akin Residence Carlsbad, California Job No. 19-12322 Page 12 California. This M7.2 event, the Sierra El Mayor earthquake, occurred in northern Baja California, approximately 40 miles south of the Mexico-USA border at shallow depth along the principal plate boundary between the North American and Pacific plates. According to the U. S. Geological Survey this is an area with a high level of historical seismicity, and it has recently also been seismically active, though this is the largest event to strike in this area since 1892. The April 4, 2010, earthquake appears to have been larger than the M6.9 earthquake in 1940 or any of the early 20th century events (e.g., 1915 and 1934) in this region of northern Baja California. The event caused widespread damage to structures, closure of businesses, government offices and schools, power outages, displacement of people from their homes and injuries in the nearby major metropolitan areas of Mexicali in Mexico and Calexico in Southern California . This event's aftershock zone extends significantly to the northwest, overlapping with the portion of the fault system that is thought to have ruptured in 1892. Some structures in the San Diego area experienced minor damage and there were some injuries. Ground motions for the April 4, 2010, main event, recorded at stations in San Diego and reported by the California Strong Motion Instrumentation Program (CSMIP), ranged up to 0.058g. Aftershocks from this event continue to the date of this report along the trend northwest and south of the original event, including within San Diego County, closer to the San Diego metropolitan area. There have been hundreds of these earthquakes including events up to MS. 7. On July 7, 2010, a MS.4 earthquake occurred in Southern California at 4:53 pm (Pacific Time) about 30 miles south of Palm Springs, 25 miles southwest of Indio, and 13 miles north-northwest of Borrego Springs. The earthquake occurred near the Coyote Creek segment of the San Jacinto Fault. The earthquake exhibited right lateral slip to the northwest, consistent with the direction of movement on the San Akin Residence Carlsbad, California Job No. 19-12322 Page 13 Jacinto Fault. The earthquake was felt throughout Southern California, with strong shaking near the epicenter. It was followed by more than 60 aftershocks of Ml.3 and greater during the first hour. Seismologists expect continued aftershock activity. In the last 50 years, there have been four other earthquakes in the magnitude M5.0 range within 20 kilometers of the Coyote Creek segment: MS.8 in 1968, M5.3 on 2/25/1980, MS.0 on 10/31/2001, and MS.2 on 6/12/2005. The biggest earthquake near this location was the M6.0 Buck Ridge earthquake on 3/25/1937. VII. SITE-SPECIFIC SOIL & GEOLOGIC DESCRIPTION A. Stratigraphy Our field work, reconnaissance and review of the geologic map by Kennedy and Tan, 2007, "Geologic Map of Oceanside, 30'x60' Quadrangle, CA," indicate that the site is underlain by Quaternary-age Old Paralic Deposits (QOPG-7) formational materials. The formational soils are overlain by approximately 2 to 2½ feet of topsoil and fill soils across the lot (refer to the Excavation Logs, Figure Nos. IIIa-d). Figure No. IV presents a plan view geologic map (Kennedy and Tan, 2007) of the general area of the site. Fill and Topsoils (Oaf): The lot is overlain by approximately 2 to 2½ feet of topsoil and fill soils as encountered in all of the exploratory excavations HP-1 through HP-4. The encountered fill and topsoils generally consists of loose to medium dense, slightly moist to moist, light brown to dark reddish brown silty sand, of low expansion potential, and are not considered suitable in their current condition for support of loads from new structures or additional fill. Refer to Figure No. III. - - ... ---- - - .. .... .. ----... --.. --... ... - ------ .. - -.. .. --... .. .. ------- Akin Residence Carlsbad, California Job No. 19-12322 Page 14 Old Paralic Deposits (Qoon-7}: The encountered formational materials consist primarily of medium dense to dense, moist, reddish brown, clayey sand. The formational soils were encountered at a depth of approximately 2 to 2½ feet in all exploratory excavations. The formational soils are considered to have a low expansion potential and have good bearing strength characteristics. Refer to Figure No. III. B. Structure No unfavorable geologic structure was observed within our exploratory excavations . The mapped Santiago Formation materials in the area of the site, underlying the Old Paralic Deposits, generally strike north 4 degrees east and dip east-southeast 10 degrees. c . Limitations The exploratory excavation logs and related information depict subsurface conditions only at the specific locations shown on the site plan and on the particular date designated on the logs. Subsurface conditions at other locations may differ from conditions occurring at these test pit locations. Also, the passage of time may result in changes in the subsurface conditions due to environmental changes. VIII. GEOLOGIC HAZARDS • The following is a discussion of the geologic conditions and hazards common to this -area of the City of Carlsbad, as well as project-specific geologic information relating -to development of the subject property. -... -----.. Akin Residence Carlsbad, California A. Local and Regional Faults Job No. 19-12322 Page 15 Reference to the geologic map of the area (Kennedy and Tan, 2007), Figure No. IV, indicates that no faults are shown to cross the site. In our explicit professional opinion, neither an active fault nor a potentially active fault underlies the site. Rose Canyon Fault: The Rose Canyon Fault Zone (Mount Soledad and Rose Canyon Faults) is located approximately 5 miles southwest of the subject site. The Rose Canyon Fault is mapped trending north-south from Oceanside to downtown San Diego, from where it appears to head southward into San Diego Bay, through Coronado and offshore. The Rose Canyon Fault Zone is considered to be a complex zone of onshore and offshore, en echelon strike slip, oblique reverse, and oblique normal faults. The Rose Canyon Fault is considered to be capable of generating an M7.2 earthquake and is considered microseismically active, although no significant recent earthquakes are known to have occurred on the fault. Investigative work on faults that are part of the Rose Canyon Fault Zone at the Police Administration and Technical Center in downtown San Diego, at the SDG&E facility in Rose Canyon, and within San Diego Bay and elsewhere within downtown San Diego, has encountered offsets in Holocene (geologically recent) sediments. These findings confirm Holocene displacement on the Rose Canyon Fault, which was designated an "active" fault in November 1991 (Hart E.W. and W. A. Bryant, 2007, Fault-Rupture Hazard Zones in California, California Geological Survey Special Publication 42). Coronado Bank Fault: The Coronado Bank Fault is located approximately 20 miles southwest of the site. Evidence for this fault is based upon geophysical data (acoustic profiles) and the general alignment of epicenters of recorded seismic activity (Greene, 1979). The Oceanside earthquake of MS.3 recorded July 13, 1986, is known to have -- --... .... ----- ... -.. .. -.. ... ... .. -.. -.. .. ... - - -.. ---... - -... ..... --- --.. - - .... , - - - - - .. ---- Akin Residence Carlsbad, California Job No. 19-12322 Page 16 been centered on the fault or within the Coronado Bank Fault Zone. Although this fault is considered active, due to the seismicity within the fault zone, it is significantly less active seismically than the Elsinore Fault (Hileman, 1973). It is postulated that the Coronado Bank Fault is capable of generating a M7.6 earthquake and is of great interest due to its close proximity to the greater San Diego metropolitan area . Newport-Inglewood Fault: The Newport-Inglewood Fault Zone is located approximately 6 miles northwest of the site. A significant earthquake (M6.4) occurred along this fault on March 10, 1933. Since then no additional significant events have occurred. The fault is believed to have a slip rate of approximately 0.6 mm/yr with an unknown recurrence interval. This fault is believed capable of producing an earthquake of M6.0 to M7.4 (SCEC, 2004). Elsinore Fault: The Elsinore Fault is located approximately 25 miles northeast of the site. The fault extends approximately 200 kilometers (125 miles) from the Mexican border to the northern end of the Santa Ana Mountains. The Elsinore Fault zone is a 1-to 4-mile-wide, northwest-southeast-trending zone of discontinuous and en echelon faults extending through portions of Orange, Riverside, San Diego, and Imperial Counties. Individual faults within the Elsinore Fault Zone range from less than 1 mile to 16 miles in length. The trend, length and geomorphic expression of the Elsinore Fault Zone identify it as being a part of the highly active San Andreas Fault system. Like the other faults in the San Andreas system, the Elsinore Fault is a transverse fault showing predominantly right-lateral movement. According to Hart, et al. (1979), this movement averages less than 1 centimeter per year. Along most of its length, the Elsinore Fault Zone is marked by a bold topographic expression consisting of linearly aligned ridges, swales and hallows. Faulted Holocene alluvial deposits Akin Residence Carlsbad, California Job No. 19-12322 Page 17 (believed to be less than 11,000 years old) found along several segments of the fault zone suggest that at least part of the zone is currently active. Although the Elsinore Fault Zone belongs to the San Andreas set of active, northwest- trending, right-slip faults in the southern California area (Crowell, 1962), it has not been the site of a major earthquake in historic time, other than a M6.0 earthquake near the town of Elsinore in 1910 (Richter, 1958; Toppozada and Parke, 1982). However, based on length and evidence of late-Pleistocene or Holocene displacement, Greensfelder ( 1974) has estimated that the Elsinore Fault Zone is reasonably capable of generating an earthquake ranging from M6.8 to M7 .1. Faulting evidence exposed in trenches placed in Glen Ivy Marsh across the Glen Ivy North Fault (a strand of the Elsinore Fault Zone between Corona and Lake Elsinore), suggest a maximum earthquake recurrence interval of 300 years, and when combined with previous estimates of the long-term horizontal slip rate of 0.8 to 7 .0 mm/year, suggest typical earthquakes of M6.0 to M7.0 (Rockwell, 1985). San Jacinto Fault: The San Jacinto Fault is located 47 miles to the northeast of the site. The San Jacinto Fault Zone consists of a series of closely spaced faults, including the Coyote Creek Fault, that form the western margin of the San Jacinto Mountains. The fault zone extends from its junction with the San Andreas Fault in San Bernardino, southeasterly toward the Brawley area, where it continues south of the international border as the Imperial Transform Fault (Earth Consultants International [ECI], 2009). The San Jacinto Fault zone has a high level of historical seismic activity, with at least 10 damaging earthquakes (M6.0 to M7.0) having occurred on this fault zone between 1890 and 1986. Earthquakes on the San Jacinto Fault in 1899 and 1918 caused fatalities in the Riverside County area. Offset across this fault is predominantly right- - - - - -... - - ----- --- -.. - - - - -.... ... -... -- ... -----... -------- - - -... -------.. Akin Residence Carlsbad, California Job No. 19-12322 Page 18 lateral, similar to the San Andreas Fault, although some investigators have suggested that dip-slip motion contributes up to 10% of the net slip (ECI, 2009) . The segments of the San Jacinto Fault that are of most concern to major metropolitan areas are the San Bernardino, San Jacinto Valley and Anza segments. Fault slip rates on the various segments of the San Jacinto are less well constrained than for the San Andreas Fault, but the available data suggest slip rates of 12 ±6 mm/yr for the northern segments of the fault, and slip rates of 4 ±2 mm/yr for the southern segments. For large ground-rupturing earthquakes on the San Jacinto fault, various investigators have suggested a recurrence interval of 150 to 300 years. The Working Group on California Earthquake Probabilities (WGCEP, 2008) has estimated that there is a 31 percent probability that an earthquake of M6. 7 or greater will occur within 30 years on this fault. Maximum credible earthquakes of M6.7, M6.9, and M7.2 are expected on the San Bernardino, San Jacinto Valley and Anza segments, respectively, capable of generating peak horizontal ground accelerations of 0.48g to 0.53g in the County of Riverside, (ECI, 2009). A M5.4 earthquake occurred on the San Jacinto Fault on July 7, 2010. The United States Geological Survey has issued the following statements with respect to the recent seismic activity on southern California faults: The San Jacinto fault, along with the Elsinore, San Andreas, and other faults, is part of the plate boundary that accommodates about 2 inches/year of motion as the Pacific plate moves northwest relative to the North American plate. The largest recent earthquake on the San Jacinto fault, near this location, the M6.5 1968 Borrego Mountain earthquake April 8, 1968, occurred about 25 miles southeast of the July 7, 2010, M5.4 earthquake. This M5.4 earthquake follows the 4th of April 2010, Easter Sunday, M7.2 earthquake, located about 125 miles to the south, well south of the US Mexico international border. A M4.9 earthquake occurred in the same Akin Residence Carlsbad, California Job No. 19-12322 Page 19 8. area on June 12th at 8:08 pm (Pacific Time). Thus this section of the San Jacinto fault remains active. Seismologists are watching two major earthquake faults in southern California. The San Jacinto fault, the most active earthquake fault in southern California, extends for more than 100 miles from the international border into San Bernardino and Riverside, a major metropolitan area often called the Inland Empire. The Elsinore fault is more than 110 miles long, and extends into the Orange County and Los Angeles area as the Whittier fault. The Elsinore fault is capable of a major earthquake that would significantly affect the large metropolitan areas of southern California. The Elsinore fault has not hosted a major earthquake in more than 100 years. The occurrence of these earthquakes along the San Jacinto fault and continued aftershocks demonstrates that the earthquake activity in the region remains at an elevated level. The San Jacinto fault is known as the most active earthquake fault in southern California. Caltech and USGS seismologist continue to monitor the ongoing earthquake activity using the Caltech/USGS Southern California Seismic Network and a GPS network of more than 100 stations. Other Geologic Hazards - - - - - - -... - - -- Ground Rupture: Ground rupture is characterized by bedrock slippage along an - established fault and may result in displacement of the ground surface. For ground - rupture to occur along a fault, an earthquake usually exceeds MS.0. If a MS.0 earthquake were to take place on a local fault, an estimated surface-rupture length 1 mile long could be expected (Greensfelder, 1974 ). Our investigation indicates that the subject site is not directly on a known active fault trace and, therefore, the risk of ground rupture is remote. Liquefaction: The liquefaction of saturated sands during earthquakes can be a major cause of damage to buildings. Liquefaction is the process by which soils are transformed into a viscous fluid that will flow as a liquid when unconfined. It occurs primarily in loose, saturated sands and silts when they are sufficiently shaken by an -----.. - -.. - -.... ---- - - ------ -... -.. - - - - ----- Akin Residence Carlsbad, California Job No. 19-12322 Page 20 earthquake. On this site, the risk of liquefaction of foundation materials due to seismic shaking is considered to be low due to the medium dense to dense nature of the natural-ground material and the lack of a shallow static groundwater surface under the site. In our opinion, the site does not have a potential for soil strength loss to occur due to a seismic event. Tsunami: A tsunami is a series of long waves generated in the ocean by a sudden displacement of a large volume of water. Underwater earthquakes, landslides, volcanic eruptions, meteoric impacts, or onshore slope failures can cause this displacement. Tsunami waves can travel at speeds averaging 450 to 600 miles per hour. As a tsunami nears the coastline, its speed diminishes, its wave length decreases, and its height increases greatly. After a major earthquake or other near- shore tsunami-inducing activity occurs, a tsunami could reach the shore within a few minutes. One coastal community may experience no damaging waves while another may experience very destructive waves. Some low-lying areas could experience severe inland inundation of water and deposition of debris. Wave heights and run-up elevations from tsunami along the San Diego Coast have historically fallen within the normal range of the tides (Joy 1968). The largest tsunami effect recorded in San Diego since 1950 was May 22, 1960, which had a maximum wave height of 2.1 feet (NOAA, 1993). In this event, 80 meters of dock were destroyed and a barge sunk in Quivera Basin. Other tsunamis felt in San Diego County occurred on November 5, 1952, with a wave height of 2.3 feet caused by an earthquake in Kamchatka; March 9, 1957, with a wave height of 1.5 feet; May 22, 1960, at 2.1 feet; March 27, 1964, with a wave height of 3.7 feet and September 29, 2009, with a wave height of 0.5 feet. It should be noted that damage does not necessarily occur in direct relationship to wave height, illustrated by the fact that the Akin Residence Carlsbad, California Job No. 19-12322 Page 21 damage caused by the 2.1-foot wave height in 1960 was worse than damage caused by several other tsunamis with higher wave heights. Historical wave heights and run-up elevations from tsunamis that have impacted the San Diego Coast have historically fallen within the normal range of the tides (Joy, 1968). The risk of a tsunami affecting the site is considered low to moderate as the site is situated at an elevation of approximately 57 feet above mean sea level and approximately 500 feet to an exposed beach. In addition, the site is not mapped within a possible inundation zone on the California Geological Survey's 2009 "Tsunami Inundation Map for Emergency Planning, Oceanside Quadrangle, San Diego County". C. Geologic Hazards Summary It is our opinion, based upon a review of the available maps, our research and our site investigation, that the site is underlain by relatively stable formational materials and is suited for the for the proposed residential project and associated improvements provided the recommendations herein are implemented. No significant geologic hazards are known to exist on the site that would prevent the proposed construction. Ground shaking from earthquakes on active southern California faults and active faults in northwestern Mexico is the greatest geologic hazard at the property. Design of building structures in accordance with the current building codes would reduce the potential for injury or loss of human life. Buildings constructed in accordance with current building codes may suffer significant damage but should not undergo total collapse. In our explicit professional opinion, no "active" or "potentially active" faults underlie the project site. - - - - - - - - --- ----- - ---. ... - ... --- ... ... -.. -- .. -... -.. ----- •· - ---... ..,., ... ----.. Akin Residence Carlsbad, California IX. GROUNDWATER Job No. 19-12322 Page 22 No groundwater was encountered during the course of our field investigation and we do not anticipate significant groundwater problems to develop in the future, if the property is developed as proposed and proper drainage is implemented and maintained. The true groundwater surface is assumed to be at a depth of over 50 feet below the existing and planned building pads. Based on exploratory drilling throughout San Diego County, we would expect minor seeps between the ground surface and true water table due to transient "perching" of vadose water on exceptionally dense, low permeability beds within the formational materials . It should be kept in mind that any required construction operations will change surface drainage patterns and/or reduce permeabilities due to the densification of compacted soils. Such changes of surface and subsurface hydrologic conditions, plus irrigation of landscaping or significant increases in rainfall, may result in the appearance of surface or near-surface water at locations where none existed previously. The damage from such water is expected to be localized and cosmetic in nature, if good positive drainage is implemented, as recommended in this report, during and at the completion of construction. On properties such as the subject site where dense, low permeability soils exist at shallow depths, even normal landscape irrigation practices on the property or neighboring properties, or periods of extended rainfall, can result in shallow "perched" water conditions. The perching (shallow depth) accumulation of water on a low permeability surface can result in areas of persistent wetting and drowning of lawns, plants and trees. Resolution of such conditions, should they occur, may require site-specific design and construction of subdrain and shallow "wick" drain dewatering systems . Akin Residence Carlsbad, California Job No. 19-12322 Page 23 Subsurface drainage with a properly designed and constructed subdrain system will be required along with continuous back drainage behind any proposed lower-level basement walls, property line retaining walls, or any perimeter stem walls for raised- wood floors where the outside grades are higher than the crawl space grades. Furthermore, crawl spaces, if used, should be provided with the proper cross- ventilation to help reduce the potential for moisture-related problems. Additional recommendations may be required at the time of construction. It must be understood that unless discovered during site exploration or encountered during site construction operations, it is extremely difficult to predict if or where perched or true groundwater conditions may appear in the future. When site fill or formational soils are fine-grained and of low permeability, water problems may not become apparent for extended periods of time. Water conditions, where suspected or encountered during construction, should be evaluated and remedied by the project civil and geotechnical consultants. The project developer and property owner, however, must realize that post-construction appearances of groundwater may have to be dealt with on a site-specific basis. Proper functional surface drainage should be implemented and maintained at the property. X. CONCLUSIONS AND RECOMMENDATIONS The following conclusions and recommendations are based upon the practical field investigation conducted by our firm, and resulting laboratory tests, in conjunction with our knowledge and experience with similar soils in the Carlsbad area. The opinions, conclusions, and recommendations presented in this report are contingent upon Geotechnical Exploration, Inc. being retained to review the final plans and - - - --- - - -..... ---.... --- -.... ---... - - -.... ----- - - ------ - --- - --- ---.. -- .... Akin Residence Carlsbad, California Job No. 19-12322 Page 24 specifications as they are developed and to observe the site earthwork and installation of foundations. Accordingly, we recommend that the following paragraph be included on the grading and foundation plans for the project. A. 1. 2. If the geotechnical consultant of record is changed for the project, the work shall be stopped until the replacement has agreed in writing to accept the responsibility within their area of technical competence for approval upon completion of the work. It shall be the responsibility of the permittee to notify the City Engineer in writing of such change prior to the recommencement of grading and/or foundation installation work. Preparation of Soils for Site Development Clearing and Stripping: The existing structure to be demolished, and vegetation on the lot should be removed prior to the preparation of the building pad and areas to receive associated improvements. This includes any roots from existing trees and shrubbery. Holes resulting from the removal of root systems or other buried obstructions that extend below the planned grades should be cleared and backfilled with properly compacted fill. Building Pad Surface and Subgrade Preparation: After the building pad has been cleared, stripped, and the required excavations made to remove the existing loose or disturbed surface fill, at least the upper 2½ feet of pad fill and topsoils should be removed and recompacted. The bottom of the excavation should be extended to expose medium dense to dense formational soils, scarified to a depth of 6 inches, moisture conditioned, and compacted to the requirements for structural fill. The areal extent required to remove the surficial soils should be confirmed by our representatives during the excavation work based on examination of the soils being exposed. The lateral extent of the excavation and recompaction should be at least 5 feet beyond the edge of Akin Residence Carlsbad, California Job No. 19-12322 Page 25 3. 4. 5. the perimeter ground level foundations of the new residential structure and any areas to receive exterior improvements where feasible. Material for Fill: Existing on-site soils with an organic content of less than 3 percent by volume are, in general, suitable for use as fill. Imported fill material, where required, should have a low-expansion potential (Expansion Index of 50 or less per ASTM D4829-11). In addition, both imported and existing on-site materials for use as fill should not contain rocks or lumps more than 6 inches in greatest dimension if the fill soils are compacted with heavy compaction equipment ( or 3 inches in greatest dimension if compacted with lightweight equipment). All materials for use as fill should be approved by our representative prior to importing to the site. Expansive Soil Conditions: We do not anticipate that expansive soils will be encountered during grading. Should such on-site soils be used as fill, they should be moisture conditioned to at least 5 percent above optimum moisture content, compacted to 88 to 92 percent. Soils of medium or greater expansion potential should not be used as retaining wall backfill soils. Fill Compaction: All structural fill should be compacted to a minimum degree of compaction of 90 percent based upon ASTM D1557-12. Fill material should be spread and compacted in uniform horizontal lifts not exceeding 8 inches in uncompacted thickness. Before compaction begins, the fill should be brought to a water content that will permit proper compaction by either: (1) aerating and drying the fill if it is too wet, or (2) watering the fill if it is too dry. Each lift should be thoroughly mixed before compaction to ensure a uniform distribution of moisture. For low expansive soils, the moisture content should be within 2 percent of optimum. We do not anticipate that medium to highly -------..... ----- - ----- .. -----.. - ... - -- -------------------... -.. -- ------... --.. ----... Akin Residence Carlsbad, California Job No. 19-12322 Page 26 6. expansive soils will be encountered on the site. However, if they are encountered, the moisture content should be at least 5 percent over optimum. Once placed, soil moisture content of the fill soils should be maintained by sprinkling daily. If heavy compaction equipment is utilized, oversize material more than 6 inches in diameter should be removed from the fill. If lightweight compaction equipment is used, oversize material more than 3 inches in diameter should be removed. Any rigid improvements founded on the existing surface soils can be expected to undergo movement and possible damage. Geotechnica/ Exploration, Inc. takes no responsibility for the performance of any improvements built on loose natural soils or inadequately compacted fills. Subgrade soils in any exterior area receiving concrete improvements should be verified for compaction and moisture within 48 hours prior to concrete placement. No uncontrolled fill soils should remain after completion of the site work. In the event that temporary ramps or pads are constructed of uncontrolled fill soils, the loose fill soils should be removed and/or recompacted prior to completion of the grading operation. Trench and Retaining Wall Backfill: New utility trenches and retaining walls should be backfilled with imported or on-site low-expansive compacted fill; gravel is also a suitable backfill material but should be used only if space constraints will not allow the use of compaction equipment. Gravel can also be used as backfill around perforated subdrains. All backfill material should be placed in lift thicknesses appropriate to the type of compaction equipment Akin Residence Carlsbad, California Job No. 19-12322 Page 27 utilized and compacted to a minimum degree of compaction of 90 percent by mechanical means. In pavement areas, that portion of the trench backfill within the pavement section should conform to the material and compaction requirements of the adjacent pavement section. In addition, the low- expansion potential fill layer should be maintained in utility trench backfill within the building and adjoining exterior slab areas. Our experience has shown that even shallow, narrow trenches (such as for irrigation and electrical lines) that are not properly compacted can result in problems, particularly with respect to shallow groundwater accumulation and migration. B. Design Parameters for Proposed Foundations 7. 8. Continuous Footings: Footings for new structure or improvements should bear on undisturbed formational materials or properly compacted fill soils. The footings should be founded at least 18 inches below the lowest adjacent finished grade when founded into properly compacted fill or into formational material. Footings located adjacent to utility trenches should have their bearing surfaces situated below an imaginary 1.5: 1.0 plane projected upward from the bottom edge of the adjacent utility trench. Bearing Values: At the recommended depths, footings on native, medium dense formational soil or properly compacted fill soil may be designed for allowable bearing pressures of 2,500 pounds per square foot (psf) for combined dead and live loads and increased one-third for all loads, including wind or seismic. The footings should have a minimum width of 12 inches. - -----------.... ---... ---... .. ------.... - - - ------ -- -.. ---- - ... --- - - -- Akin Residence Carlsbad, California Job No. 19-12322 Page 28 9. Seismic Design Criteria: Site-specific seismic design criteria for the proposed residence are presented in the following table in accordance with Section 1613 of the 2016 CBC, which incorporates by reference ASCE 7-10 for seismic design. We have determined the mapped spectral acceleration values for the site, based on a latitude of 33.1301 degrees and longitude of -117.3334 degrees, utilizing a third party tool provided by the USGS, which provides a solution for ASCE 7-10 (Section 1613 of the 2016 CBC) utilizing digitized files for the Spectral Acceleration maps. Based on our experience with similar soil conditions, we have assigned a Site Soil Classification of D. TABLE I Mapped Spectral Acceleration Values and Design Parameters Ss Fa Fv Sms 1.173 1.031 1.549 1.209 10. Footing Reinforcemem: All continuous footings should contain top and bottom reinforcement to provide structural continuity and to permit spanning of local irregularities. We recommend that a minimum of two No. 5 top and two No. 5 bottom reinforcing bars be provided in the footings. Footings over 18 inches in depth should be reinforced as specified by the structural engineer. A minimum clearance of 3 inches should be maintained between steel reinforcement and the bottom or sides of the footing. Isolated square footings should contain, as a minimum, a grid of three No. 4 steel bars on 12-inch centers, both ways. In order for us to offer an opinion as to whether the footings are founded on soils of sufficient load bearing capacity, it is essential that our representative inspect the footing excavations prior to the placement of reinforcing steel or concrete. Akin Residence Carlsbad, California Job No. 19-12322 Page 29 NOTE: The project Civil/Structural Engineer should review all reinforcing schedules. The reinforcing minimums recommended herein are not to be construed as structural designs, but merely as minimum reinforcement to reduce the potential for cracking and separations. 11. Lateral Loads: Lateral load resistance for structure foundations may be developed in friction between the foundation bottoms and the supporting subgrade. An allowable friction coefficient of 0.40 is considered applicable. An additional allowable passive resistance equal to an equivalent fluid weight of 300 pounds per cubic foot (pcf) acting against the new foundations may be used in design provided the footings are poured neat against the adjacent undisturbed formational materials and/or properly compacted fill materials. These lateral resistance values assume a level surface in front of the footing for a minimum distance of three times the embedment depth of the footing. 12. Settlement: Settlements under foundations with building loads that comply with our recommendations are expected to be within tolerable limits for the proposed structure. For footings designed in accordance with the recommendations presented in the preceding paragraphs, we anticipate that total settlements should not exceed 1 inch and that post-construction differential angular rotation should be less than 1/240. 13. Retaining Walls (if applicable): Retaining walls must be designed to resist lateral earth pressures and any additional lateral pressures caused by surcharge loads on the adjoining retained surface. We recommend that unrestrained ( cantilever) walls with level backfill be designed for an equivalent fluid pressure of 38 pcf. We recommend that restrained walls (i.e., basement walls or any walls with angle points that restrain them from rotation) with level - - - - - - - - -..... - --- -.... -- - - .., -... .. ------.. ... ------ .. --.. -.. - ----- ----- Akin Residence Carlsbad, California Job No. 19-12322 Page 30 backfill be designed for an equivalent fluid pressure of 56 pcf. Unrestrained walls with up to 2.0: 1.0 sloping backfills should be designed for an equivalent fluid pressure of 52 pcf. Restrained walls with up to 2.0: 1.0 sloping backfills should be designed for an equivalent fluid pressure of 76 pcf. Wherever walls will be subjected to surcharge loads, they should also be designed for an additional uniform lateral pressure equal to one-third the anticipated vertical surcharge pressure in the case of unrestrained walls and an additional one- half the anticipated vertical surcharge pressure in the case of restrained walls. For seismic design of unrestrained walls, we recommend that the seismic pressure increment be taken as a fluid pressure distribution utilizing an equivalent fluid weight of 15 pcf. For restrained walls, we recommend the seismic pressure increment be waived . The preceding design pressures assume that the walls are backfilled with low expansion potential materials (Expansion Index less than 50) and that there is sufficient drainage behind the walls to prevent the build-up of hydrostatic pressures from surface water infiltration. We recommend, in addition to water proofing, that back drainage be provided by a composite drainage material such as MiraDrain 6000/6200 or equivalent. The back drain material should terminate 12 inches below the finish surface where the surface is covered by slabs or 18 inches below the finish surface in landscape areas. Waterproofing should continue to 6 inches above top of wall. A subdrain (such as Total Drain or perforated pipe in an envelope of crushed rock gravel a maximum of 1 inch in diameter and wrapped with geofabric such as Mirafi 140N), should be placed at the bottom of retaining walls. Akin Residence Carlsbad, California Job No. 19-12322 Page 31 c. Backfill placed behind the walls should be compacted to a minimum degree of compaction of 90 percent using light compaction equipment. If heavy equipment is used, the walls should be appropriately temporarily braced. Concrete Slab On-Grade Criteria Slabs on-grade may only be used on new, properly compacted fill or when bearing on medium dense to dense formational soils. 14. Minimum Floor Slab Thickness and Reinforcement: Based on our experience, we have found that, for various reasons, floor slabs occasionally crack. Therefore, we recommend that all slabs on-grade contain at least a minimum amount of reinforcing steel to reduce the separation of cracks, should they occur. Slab subgrade soil should be verified by a Geotechnical Exploration, Inc. representative to have the proper moisture content within 48 hours prior to placement of the vapor barrier and pouring of concrete. New interior floor slabs should be a minimum of 4 inches actual thickness and be reinforced with No. 3 bars on 18-inch centers, both ways, placed at midheight in the slab. Soil moisture content should be kept above the optimum prior to waterproofing placement under the new concrete slab. 15. Slab Moisture Emission: Although it is not the responsibility of geotechnical engineering firms to provide moisture protection recommendations, as a service to our clients we provide the following discussion and suggested minimum protection criteria. Actual recommendations should be provided by the Project Architect and waterproofing consultants or product manufacturer. - - . .., - ----- -·-- --.. .. ----- ----- - - - - -- - ----- --- - - --- ------- -- Akin Residence Carlsbad, California Job No. 19-12322 Page 32 Soil moisture vapor can result in damage to moisture-sensitive floors, some floor sealers, or sensitive equipment in direct contact with the floor, in addition to mold and staining on slabs, walls and carpets. The common practice in Southern California is to place vapor retarders made of PVC, or of polyethylene. PVC retarders are made in thickness ranging from 10-to 60-mil. Polyethylene retarders, called visqueen, range from 5-to 10-mil in thickness. These products are no longer considered adequate for moisture protection and can actually deteriorate over time. Specialty vapor retarding and barrier products possess higher tensile strength and are more specifically designed for and intended to retard moisture transmission into and through concrete slabs. The use of such products is highly recommended for reduction of floor slab moisture emission. The following American Society for Testing and Materials (ASTM) and American Concrete Institute (ACI) sections address the issue of moisture transmission into and through concrete slabs: ASTM El 745-97 (2009) Standard Specification for Plastic Water Vapor Retarders Used in Contact Concrete Slabs; ASTM E154-88 (2005) Standard Test Methods for Water Vapor Retarders Used in Contact with Earth; ASTM E96-95 Standard Test Methods for Water Vapor Transmission of Materials; ASTM E1643-98 (2009) Standard Practice for Installation of Water Vapor Retarders Used in Contact Under Concrete Slabs; and ACI 302.2R-06 Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials. 15.1 Based on the above, we recommend that the vapor barrier consist of a minimum 15-mil extruded polyolefin plastic (no recycled content or woven materials permitted). Permeance as tested before and after Akin Residence Carlsbad, California Job No. 19-12322 Page 33 mandatory conditioning (ASTM El 745 Section 7.1 and subparagraphs 7.1.1-7.1.5) should be less than 0.01 perms (grains/square foot/hour/per inch of Mercury) and comply with the ASTM El 745 Class A requirements. Installation of vapor barriers should be in accordance with ASTM E1643. The basis of design is 15-mil StegoWrap vapor barrier placed per the manufacturer's guidelines. Reef Industries Vapor Guard membrane has also been shown to achieve a permeance of less than 0.01 perms. We recommend that the slab be poured directly on the vapor barrier, which is placed directly on the prepared subgrade soil. 15.2 Common to all acceptable products, vapor retarder/barrier joints must be lapped and sealed with mastic or the manufacturer's recommended tape or sealing products. In actual practice, stakes are often driven through the retarder material, equipment is dragged or rolled across the retarder, overlapping or jointing is not properly implemented, etc. All these construction deficiencies reduce the retarder's effectiveness. In no case should retarder/barrier products be punctured or gaps be allowed to form prior to or during concrete placement. 15.3 Vapor retarders/barriers do not provide full waterproofing for structures constructed below free water surfaces. They are intended to help reduce or prevent vapor transmission and/or capillary migration through the soil and through the concrete slabs. Waterproofing systems must be designed and properly constructed if full waterproofing is desired. The owner and project designers should be consulted to determine the specific level of protection required. - ----- -... - - - --- --- ---.. --- - - -----.. --- ... --.... --- •· - ... -... - •· -----.... - -· ---.. -.... Akin Residence Carlsbad, California Job No. 19-12322 Page 34 15.4 Following placement of any concrete floor slabs, sufficient drying time must be allowed prior to placement of floor coverings. Premature placement of floor coverings may result in degradation of adhesive materials and loosening of the finish floor materials. 16. Concrete Isolation Joints: We recommend the project Civil/Structural Engineer 17. incorporate isolation joints and sawcuts to at least one-fourth the thickness of the slab in any floor designs. The joints and cuts, if properly placed, should reduce the potential for and help control floor slab cracking. We recommend that concrete shrinkage joints be spaced no farther than approximately 20 feet apart, and also at re-entrant corners. However, due to a number of reasons (such as base preparation, construction techniques, curing procedures, and normal shrinkage of concrete), some cracking of slabs can be expected. Structural slabs should not be provided with control joints. Exterior Slab Thickness and Reinforcement: Exterior concrete slabs should be at least 4 inches thick. As a minimum for protection of on-site improvements, we recommend that all nonstructural concrete slabs (such as patios, sidewalks, etc.), be founded on properly compacted and tested fill or medium dense native formation and be underlain (if needed) by 2 inches and no more than 3 inches of clean leveling sand, with No. 3 bars at 18-inch centers, both ways, at the center of the slab. Exterior slabs should contain adequate isolation and control joints. The performance of on-site improvements can be greatly affected by soil base preparation and the quality of construction. It is therefore important that all improvements are properly designed and constructed for the existing soil conditions. The improvements should not be built on loose soils or fills placed Akin Residence Carlsbad, California Job No. 19-12322 Page 35 without our observation and testing. The subgrade of exterior improvements should be verified as properly prepared within 48 hours prior to concrete placement. For exterior slabs with the minimum shrinkage reinforcement, control joints should be placed at spaces no farther than 15 feet apart or the width of the slab, whichever is less, and also at re-entrant corners. Control and isolation joints in exterior slabs should be sealed with elastomeric joint sealant. The sealant should be inspected every 6 months and be properly maintained. 18. Garage Slab and Driveway: We recommend that the garage slab and new driveway, subject only to automobile and light truck traffic be 5 inches thick and be supported directly on properly prepared on-site subgrade soils. The upper 12 inches of the subgrade below the driveway pavement should be compacted to a minimum degree of compaction of 95 percent just prior to paving. The concrete should conform to Section 201 of The Standard Specifications for Public Works Construction, 2015 Edition, for Class 560-C- 3250. In order to control shrinkage cracking, we recommend that the garage slab be reinforced with No. 4 bars at 18-inch centers, both ways, at the center of the slab. The driveway slab may be constructed without reinforcing steel provided saw-cut, weakened-plane joints are provided at about 10-foot centers both ways and at re-entrant corners. The driveway slabs should be saw-cut as soon as practical but no more than 24 hours after the placement of the concrete. The depth of the joint should be one-quarter of the slab thickness and its width should not exceed 0.02-foot. ------.. ..... .. - - - ------... -.. - -... - ... - ---------------.. -.. ---... , - -.... - Akin Residence Carlsbad, California Job No. 19-12322 Page 36 D. Site Drainage Considerations 19. 20. Erosion Control: Appropriate erosion control measures should be taken at all times during and after construction to prevent surface runoff waters from entering footing excavations or ponding on finished building pad areas. Surface Drainage: Adequate measures should be taken to properly finish- grade the lot after the structures and other improvements are in place. Drainage waters from this site and adjacent properties should be directed away from the footings, floor slabs, and slopes, onto the natural drainage direction for this area or into properly designed and approved drainage facilities provided by the project civil engineer. Roof gutters and downspouts should be installed on the residence, with the runoff directed away from the foundations via closed drainage lines. Proper subsurface and surface drainage will help minimize the potential for waters to seek the level of the bearing soils under the footings and floor slabs. Failure to observe this recommendation could result in undermining and possible differential settlement of the structure or other improvements on the site or cause other moisture-related problems. Currently, the CBC requires a minimum !-percent surface gradient for proper drainage of building pads unless waived by the building official. Concrete pavement may have a minimum gradient of 0.5-percent . -21. Planter Drainage: Planter areas, flower beds and planter boxes should be -sloped to drain away from the footings and floor slabs at a gradient of at least --------- 5 percent within 5 feet from the perimeter walls. Any planter areas adjacent to the residence or surrounded by concrete improvements should be provided Akin Residence Carlsbad, California Job No. 19-12322 Page 37 with sufficient area drains to help with rapid runoff disposal. No water should be allowed to pond adjacent to the residence or other improvements or anywhere on the site. E. General Recommendations 22. Proiect Start Up Notification: In order to reduce work delays during site development, this firm should be contacted 48 hours prior to any need for observation of footing excavations or field density testing of compacted fill soils. If possible, placement of formwork and steel reinforcement in footing excavations should not occur prior to observing the excavations; in the event that our observations reveal the need for deepening or re-designing foundation structures at any locations, any formwork or steel reinforcement in the affected footing excavation areas would have to be removed prior to correction of the observed problem (i.e., deepening the footing excavation, recompacting soil in the bottom of the excavation, etc.). 23. Construction Best Management Practices (BMPs): Construction BMPs must be implemented in accordance with the requirements of the controlling jurisdiction. Sufficient BMPs must be installed to prevent silt, mud or other construction debris from being tracked into the adjacent street(s) or storm water conveyance systems due to construction vehicles or any other construction activity. The contractor is responsible for cleaning any such debris that may be in the street at the end of each work day or after a storm event that causes breach in the installed construction BMPs. -------.. --.. -- -... -------.. .. ------ - - -.. -.... -----.. ---------------.. -------.. -.. -- Akin Residence Carlsbad, California Job No. 19-12322 Page 38 All stockpiles of uncompacted soil and/or building materials that are intended to be left unprotected for a period greater than 7 days are to be provided with erosion and sediment controls. Such soil must be protected each day when the probability of rain is 40% or greater. A concrete washout should be provided on all projects that propose the construction of any concrete improvements that are to be poured in place. All erosion/sediment control devices should be maintained in working order at all times. All slopes that are created or disturbed by construction activity must be protected against erosion and sediment transport at all times. The storage of all construction materials and equipment must be protected against any potential release of pollutants into the environment. XI. GRADING NOTES Geotechnical Exploration, Inc. recommends that we be retained to verify the actual soil conditions revealed during site grading work and footing excavation to be as anticipated in this "Report of Preliminary Geotechnica/ Investigation" for the project. In addition, the placement and compaction of any fill or backfill soils during site grading work must be observed and tested by the soil engineer. It is the responsibility of the grading contractor to comply with the requirements on the grading plans as well as the local grading ordinance. All retaining wall and trench backfill should be properly compacted. Geotechnical Exploration, Inc. will assume no liability for damage occurring due to improperly or uncompacted backfill placed without our observations and testing. Akin Residence Carlsbad, California XII. LIMITATIONS Job No. 19-12322 Page 39 Our conclusions and recommendations have been based on available data obtained from our field investigation and laboratory analysis, as well as our experience with similar soils and formational materials located in this area of Carlsbad. Of necessity, we must assume a certain degree of continuity between exploratory excavations and/or natural exposures. It is, therefore, necessary that all observations, conclusions, and recommendations be verified at the time grading operations begin or when footing excavations are placed. In the event discrepancies are noted, additional recommendations may be issued, if required. The work performed and recommendations presented herein are the result of an investigation and analysis that meet the contemporary standard of care in our profession within the County of San Diego. No warranty is provided. As stated previously, it is not within the scope of our services to provide quality control oversight for surface or subsurface drainage construction or retaining wall sealing and base of wall drain construction. It is the responsibility of the contractor to verify proper wall sealing, geofabric installation, protection board installation (if needed), drain depth below interior floor or yard surfaces, pipe percent slope to the outlet, etc. This report should be considered valid for a period of two (2) years, and is subject to review by our firm following that time. If significant modifications are made to the building plans, especially with respect to the height and location of any proposed structures, this report must be presented to us for immediate review and possible revision. --- - -.. .. - .. - ---.. -.. -... .. --... --- .. - -.... -- .. - - -.. -... - Akin Residence Carlsbad, California Job No. 19-12322 Page 40 It is the responsibility of the owner and/or developer to ensure that the recommendations summarized in this report are carried out in the field operations and that our recommendations for design of this project are incorporated in the grading and structural plans. We should be retained to review the project plans once they are available, to verify that our recommendations are adequately incorporated in the plans. Additional or modified recommendations may be issued if warranted after plan review. This firm does not practice or consult in the field of safety engineering. We do not direct the contractor's operations, and we cannot be responsible for the safety of personnel other than our own on the site; the safety of others is the responsibility of the contractor. The contractor should notify the owner if any of the recommended actions presented herein are considered to be unsafe . .... The firm of Geotechnica/ Exploration, Inc. shall not be held responsible for .. changes to the physical condition of the property, such as addition of fill soils or _. changing drainage patterns, which occur subsequent to issuance of this report and -the changes are made without our observations, testing, and approval . ..... - - --- - -----..... Once again, should any questions arise concerning this report, please feel free to contact the undersigned. Reference to our Job No. 19-12322 will expedite a reply to your inquiries. Respectfully submitted, Jon g P.G. 15 Seni · t - - -.. - -... - ---..... - - ----- -... - - - -... -.... VICINITY MAP Carlsbad State Beach PACIFIC OCEA Thomas Bros G uide San Diego County pg l l 26-G2 Proposed Akin Residence 5290 Carlsbad Boulevard Carlsbad, CA. Figure No. I Job No. 19-12322 :Ii w ~ ~ t) UJ 0 u ca fD ~ 06 1---4 -V> d ~~ zo 1---4 ca ~ ~ 0 ~ Ln a: a :::, ~ ~ G Sl i w c5ci; ~~i;~ :I:--: =i;~ u <( 0 ~ a: .!:: 8 ~ ~ <(~:;;~5 ~ ~ ~ i ~~l;I ~I II <( .... ~ 4,1,19 SHEET NO. Cl 19-12322-p_.~ I I I I I I I Q I ~ I ! I .J ! 5 I m Q I! ~ "' ..I ~ 5 I"' ~ Ii I I I I J z :J I ~I NOlES: P1IOl'OSEll STREET NffiO'/EMEt!TS POI TEffiWNl NIA ~Al IMPllMMEIITS PftOJECT. efiSITTIIOOiMARK !Wjtu.£11,1 I O!WltWAY &CI.IIBCt/l l ~ HP-3 ~ ~ l fllSTt«ltmro\NlllSllll«:E LOT 43 ~~WN! N 3D° 38' so-w 11 o·-o· ~-O'~PTO.WIXIlfBa I l'\RX:l/llJllSNfJPT&T I I I WNNT~~~ I 2751ANJTlllill!'a!I~ I P(MEIP(lfS&IMllf.lD I.NS OCW'!ltfMJel I I IU~ t-----lU-4' I I I _____________________________ _fL-__ j I LOT\ 74 I _t __________________________ -jk:-------7 -t ~----0at-±-_____ ~,: --+---~-r-------.:-------==- ! --------- :rn ---~ HP-1 1 -fI.-1 ----__ .__,Jlill,;ll&I,-&-----~--··7 I "-!J'-t---#l \ I 1 »--· L-------~ I I ~ ,~ Scale: 1" = 15' (approximate) ---r---;-l ! ----~r --i ;~io-/ ~I I I I I I I f)/ TO==~~tL/ 11 '--·-•-·- , 'OHSHOfEDll;vE I 1 , I 11 , I j --L -------' ,, / ✓\ ' /_ --,, '' , ' -I I /',, ) \ ~DAVEWAYLOCATOI AI/TOGATE r------:.. __ ..:,J ________ ~ -~--- 6-7 [ , l ! -\rt-: I ,,.: I" 1 .,l I -flZL 1 I I I I I z i cn I I I I I I I I I I ~ ffi .., ~ I ..... ' '=' .......... , ,,, ,,, ,,, ~ F»f,qAr---,._ roef"ct.00/o '\. & 11 --_/ 'e ' 11 /"" , I I ., , 11 11 11 J:\ ~I ~I i i L _ _..__ __ ~ f-HP-4~ LOT 42 NEW 2 SJPBY BE + -, ~ ' i I F 6'-0' I ~ ! I J ~ ~ I m i I I I en ! I C? ! b l I-I F • ! .,. I l q I l i I 1 J I I 1 5.;-----; I~ J 1 1 I IHP-2 -----8'-()"YYSB __ _JI --........_ ---I u- "' ·-NEW ,, '',COVEREI / PORCH ~ X ,. II "' >--.· +aL LANfflPED I ,,, ,,, ... IJ ➔ I f <-1 /--ii t I Nk"38'50"W 11b·-o· b I f--flU-Em!NlB.Emt ~ I ~ LEGEND ~ HP-3 Approximate Location of Exploratory Handpit Approximate Location of Existing Structure Approximate Location of Proposed Structure Qaf Artificial Fill ------26'>1"-------...... Qop Quaternary Old Paralic Deposits (units 6-7) 6-7 c=J ~~~ LOT 41 &-0' IIGH WOOO FOO' lllRIMAIH SITE PLAN REFERENCE: This Plot Plan is not to be used for legal purposes. Locations and dimensions are approximate. Actual property dimensions and locations of utilities may be obtained from the Approved Building Plans or the "As-Built" Grading Plans. REFERENCE: This Plot Plan was prepared from an existing SITE PLAN by MARTIN ARCHITECTURE dated 4-1-19 and from on-site field reconnaissance performed by GEi. I ~ I LOTI 75 I I I I I I I IXIS1WG~-O'~f9a ro I I I I I I PLOT PLAN Proposed Akin Residence 5290 Carlsbad Boulevard Carlsbad, CA. Figure No. II Job No. 19-12322 DI Geotechnical ~ Exploration, Inc. ~ June2019 a, ;:::: ~ !:i (!) K )( w / EQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED \. Hand Tools 2' X 2' X 3' Handpit SURFACE ELEVATION GROUNDWATER/SEEPAGE DEPTH ± 58' Mean Sea Level Not Encountered ! FIELD DESCRIPTION AND CLASSIFICATION 5 UJ ~ CD ce DESCRIPTION AND REMARKS ~ ~ ! (Grain size, Density, Moisture, Color) ~~-Ii.~ -43/-. -li.~ ~i -f.ry SIL TY SAND , fine-to medium-grained. Loose. Moist. Dark red-brown, trace roots. FILL (Qaf) ~/-~ 1 -I SIL TY SAND , fine-to medium-grained. Loose _ to medium dense. Moist. Dark red-brown. TOPSOIL - - 2- - - - 3 - - - - - 4 - - - - - - 1-- 1 CLAYEY SAND , fine-to medium-grained. Medium dense to dense. Moist. Red-brown. OLD PARALIC DEPOSITS (Qop d Bottom@ 3' JOB NAME (/2 u (/2 ::::j SM SM SC 5-30-19 LOGGED BY JAB ~ ~'R ~ ~'R UJ o_ UJ UJ er ~~ :::::e er :::::e~ ::, ~ ~~ ::, ::, ::icn :::::e I-:::::e-ii -(I) ~~ Cl.Z ~~ ' UJ ~o 4.9 106.8 .Y PERCHED WATER TABLE Proposed Akin Residence ~ BULK BAG SAMPLE SITE LOCATION III IN-PLACE SAMPLE 5290 Carlsbad Blvd., Carlsbad, CA ■ MODIFIED CALIFORNIA SAMPLE JOB NUMBER REVIEWED BY LDR/JAC 0 NUCLEAR FIELD DENSITY TEST 19-12322 4wi~---.. , FIGURE NUMBER EXploratJon, Inc. ~ STANDARD PENETRATION TEST Illa ffe "" ~ ci .,.: ci 6-~q + c:i ~ UJ (I) :z I-_, UJ -:::::E ~z (I)-~ (I) Cl. :t: zo ~ gi5 ~~ ~~ UJ (.) CD (.) LOG No. HP-1 ~ r EQUIPMENT DIMENSION & lYPE OF EXCAVATION DATE LOGGED .... Hand Tools 2' X 2' X 3.5' Handpit 5-30-19 SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH LOGGED BY ± 57' Mean Sea Level Not Encountered JAB FIELD DESCRIPTION -(ti :,I? 0 AND 0 ~ &<[ ~ ~'[ ~ c:i I CLASSIFICATION w o _ ::d~ c:i ts ~ d -w 0:: ~~ :::;;-~q + ...J w c,j ui= => i= =>~ ·d ;;; W <n :I: 0 ~ DESCRIPTION AND REMARKS :5;;; :::;;--::Iii ~ (/) z ~'z: ...JW I-a:> u :5 w ~ (/) -(/) <n-~ 0..:I: 0.. ~ ! (Grain size, Density, Moisture, Color) c,j ~o o,.z ~; i~ zo ~8 ~ ga ~~ w ~ z W w ~ 0 _::Iii _o 0 -w m u SILTY SAND , fine-to medium-grained, SM some roots. Loose to medium dense. Moist. Dark red-brown. FILL (Qaf) 1 7.2 100.8 78 Bulk bag sample from 1'-2'. -23% passing #200 sieve. 8.1 130.0 2 SIL TY SAND , fine-to medium-grained. SM Loose to medium dense. Moist. Dark red-brown. TOPSOIL SIL TY SAND , fine-to medium-grained. 8.9 121 .4 Medium dense to dense. Moist. 3 Red-brown. OLD PARAUC DEPOSITS (Qop d 1 Bulk bag sample from 2.5'-3.5'. -25% passing #200 sieve. Bottom @ 3.5' 4 ~ ;::: ;a !5 ~ 1.5 _y PERCHED WATER TABLE JOB NAME Proposed Akin Residence ~ BULK BAG SAMPLE SITE LOCATION [I] IN-PLACE SAMPLE 5290 Car1sbad Blvd., Car1sbad, CA ■ JOB NUMBER REVIEWED BY LDR/JAC LOG No. MODIFIED CALIFORNIA SAMPLE 0 NUCLEAR FIELD DENSITY TEST 19-12322 c~a&-HP-2 FIGURE NUMBER Exploration, Inc. ~ STANDARD PENETRATION TEST lllb ~ '-~ ~ ;:: iii 5 (!) ~ 15 0 w (!) ~ (!) z ~ ~ ~ § z 0 ~ 0 ~ /.'.) 'EQUIPMENT DIMENSION & TYPE OF EXCAVATION Hand Tools 1.5' X 1.5' X 3.5' Handpit SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH ± 56' Mean Sea Level Not Encountered FIELD DESCRIPTION AND CLASSIFICATION ~ wt-------------------.--~ g ~ DESCRIPTION AND REMARKS en ~ ~ (Grain size, Density, Moisture, Color) u en :;;; K-~, > ~ I -\q1 -{\C3'i' l <:I c' j''O ~ -'~., ~I./~ SIL TY SAND , fine-to medium-grained. Loose. Slightly moist. Light brown. FILL (Qaf) SM 1 ---rt-tt,,;rt--t--::;:-:-:-::=-:-=--:-=,-----:::------,------:,,-------,-----,~-=-.,,-----t-=:,-,:-1 V SIL TY SAND , fine-to medium-grained. Medium SM -A dense. Slightly moist. Light red-brown. - ~ w WO::: (J i= :5 (/) ~5 _::::i; DATE LOGGED "'I 5-30-19 LOGGED BY JAB ~E ~ ~'§: l c:i ~ c:i :d ~ o _ ~1':: ::.~ ~q + => => ~~ ·d W U> I-~w :5cn ::::!: I--::::!: z (/) 3:z -(/) -(/) w_ t~ ~~ ~ffi ;~ i~ zo ga _o ~~ w (J cc (J 7.2 126.0 TOPSOIL II Bulk bag sample from 1'-2'. 3.1 109.4 87 2 - - -~ - 3 - - - - - 4 - - - - - - ~ [8J [I] ■ 0 '- l?j CLAYEY SAND , fine-to medium-grained. Medium dense to dense. Moist. Red-brown. OLD PARAUC DEPOSITS (Qop d Bottom @ 3.5' JOB NAME SC PERCHED WATER TA BLE Proposed Akin Residence BULK BAG SAMPLE SITE LOCATION IN-PLACE SAMPLE 5290 Carlsbad Blvd., Carlsbad, CA MODIFIED CALIFORNIA SAMPLE JOB NUMBER REVIEWED BY LDR/JAC NUCLEAR FIELD DENSITY TEST 19-12322 ;,-FIGURE NUMBER Exploratlon, Inc. STANDARD PENETRATION TEST Ille ~ LOG No. HP-3 ~ 'EQUIPMENT DIMENSION & TYPE OF EXCAVATION Hand Tools, Hand Auger 1.5' X 1.5' X 5' Handpit/ Auger Hole SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH ± 57' Mean Sea Level Not Encountered ~ ;::: = ! :I: f-0.. w 0 1 2 3 5 iii 6 l:i <., ...J w 0 ...J a:, 0.. ~ Cl) ~ FIELD DESCRIPTION AND CLASSIFICATION DESCRIPTION AND REMARKS (Grain size, Density, Moisture, Color) SIL TY SAND , fine-to medium-grained. Loose to medium dense. Moist. Dark red-brown. FILL (Qaf) SIL TY SAND , fine-to medium-grained. Loose to medium dense. Moist. Dark red-brown. TOPSOIL Hand auger from 2.5'-5'. CLAYEY SAND , fine-to medium-grained. Medium dense. Moist. Red-brown. OLD PARAUC DEPOSITS (Qop d Bottom@ 5' <ri (.) <ri ;:j SM SM SC ~ >--=-[§ .e, w wa:: ~~ u :::> ~H; :'Sen c..-c..z :z 0 'w _:::;; ~o DATE LOGGED "'I 5-30-19 LOGGED BY JAB l ~ ~'[ c:i ~ c:i ::dl:! :::.-+ ci-~q :::>~ :::>~ ·d W CI) f-...JW :::.--:::. z Cl) :!:Z ~ Cl) -Cl) Cl)-< z 0.. :I: f--i~ zo ~8 o=> :::.u 0.. 0 ~~ _,o ~~ o:::. a:, c.> ~ ,.._ _ _,__..__.._ __________________ _,__....__...._ _ ___. _ ___......_ _ _,__...._ _ ___. _ ___, _ ___,, @ <., , 0.. <., z 2 < § \. y_ ~ III ■ 0 ~ PERCHED WATER TABLE BULK BAG SAMPLE IN-PLACE SAMPLE MODIFIED CALIFORNIA SAMPLE NUCLEAR FIELD DENSITY TEST STANDARD PENETRATION TEST JOB NAME Proposed Akin Residence SITE LOCATION 5290 Carlsbad Blvd., Carlsbad, CA JOB NUMBER REVIEWED BY LDR/JAC LOG No. 19-12322 C&'4~---HP-4 FIGURE NUMBER Expforatfon, Inc. llld ffe I I I I I I I I Substat10 Pacific Ocean ._ .... OnlfloNI .. (~. hydtogl'aphy 1111d 11.-..portnelnl ll'Offi USGS digul lne graph (DI.GI ct.ta.S...o.;alO'wlO"ffWIC:..,,.,... Stleded ~beMhl,,\USG.$ dlglla~mocllilll IOEM'•l-Oft~ •~ cc,n-..,,, end .,,._, ~tom NO.AA --#'ld~dala ~•UTMm...11 Ncwl'IA1Nntan0auol1t27 EUSGS ____ _,_,.~ n.,.._,_,.f\...oedtnpe,1byhUS ~ __ "--__ _ IT.AiTIMAP""-1:lr,g NHQ,\020,IJ ~~coopetna,nwll'lhUS ~5.lwy louN,m ~,.,..Mapping Pn:ljlct. ~02001~Nc.libtw~dConNtvlCICWI Alngt'ltS'--' NoHl'tol .. ~,,..,N~ wtlN)i,,IWll'flk,l'l~ol.--~G.aloglCIII~ Tr.O.O.,l'W'1lrllo#Conwtvation,.,._no~ .. IION .........,o1,-Jl"IDIClbqPMOA1r~ Akin-OC-2008-geo.ai Proposed Akin Residence 5290 Carlsbad Boulevard Carlsbad, CA. EXCERPT FROM GEOLOGIC MAP OF THE OCEANSIDE 30' x 60' QUADRANGLE, CALIFORNIA Compiled by ----... ~ ,. -+ e --1!. +- ~ --e- ..1!. ---- Michael P. Kennedy1 and Siang S. Tan1 2007 Digital preparation by Kelly R. Bovard2, Rachel M. Alvarez', Michael J. watson2, and Carlos I. Gutierrez' 10..----•~~~._, l U.$ ~~~db'ltlac..-u.w-.rydC--.. .._.. ONSHORE MAP SYMBOLS Contact-Cootact beN,:ecn geo)ogJC \lllts; dotted where COllcaled. Faull---Sohd where xcun1dy located; duhed -.heft aprroxirrwtly located; doatd wher~ oonca!ed. U • ,q,tlmo-n block. D • "°'"""""'11 block. Ano,.· and ,unbcr mdiate direction and anglt of dip of &ult pbne. Antkllne--Sciid whtre aoc:un.tely localtd; (bird where coocnltd. S)ndlne-Sdid wbm IC<W"llely locattd; d0Ucd where concealed. OtMd <Wpreaion-Closed dqrnsm m Elstn0tt fault 200t. Landlllde-ArroWs mdicdc pnnripaJ chr«:ticca of rl'XJ\'fflltlll. Qunied whm uutcnce is qumacmble. Strike and dtp of btd, lndlntd Onrturned \'trtkal Borlzontal Strlkt and dip or l&Jlf'Ou• foll1Uon lncllntd \'erUc:al Slrikt and dip of J&nto•• Jolnll lnc.Uned VerUc:al S1rtke and dip or mttamorphk i>llaUon Inclined Strike and dip oftedlmtntar)' Joints Vtrtlcal DESCRIPTION OF MAP UNITS Old paralic deposits, undivided Figure No. IV Job No. 19-12322 •=-..=:·lnL ~ :, June2019 - - - - APPENDIX A UNIFIED SOIL CLASSIFICATION CHART SOIL DESCRIPTION Coarse-grained (More than half of material is larger than a No. 200 sieve) GRAVELS, CLEAN GRAVELS (More than half of coarse fraction is larger than No. 4 sieve size, but smaller than 3") GRAVELS WITH FINES (Appreciable amount) SANDS, CLEAN SANDS (More than half of coarse fraction is smaller than a No. 4 sieve) SANDS WITH FINES (Appreciable amount) GW GP GC SW SP SM Well-graded gravels, gravel and sand mixtures, little or no fines. Poorly graded gravels, gravel and sand mixtures, little or no fines. Clay gravels, poorly graded gravel-sand-silt mixtures Well-graded sand, gravelly sands, little or no fines Poorly graded sands, gravelly sands, little or no fines. Silty sands, poorly graded sand and silty mixtures. SC Clayey sands, poorly graded sand and clay mixtures. Fine-grained (More than half of material is smaller than a No. 200 sieve) SIL TS AND CLAYS Liquid limit Less than 50 Liquid Limit Greater than 50 HIGHLY ORGANIC SOILS (rev. 6/05) ML Inorganic silts and very fine sands, rock flour, sandy silt and clayey-silt sand mixtures with a slight plasticity CL Inorganic clays of low to medium plasticity, gravelly clays, silty clays, clean clays. OL Organic silts and organic silty clays of low plasticity. MH CH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts. Inorganic clays of high plasticity, fat clays. OH Organic clays of medium to high plasticity. PT Peat and other highly organic soils