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HomeMy WebLinkAboutMS 2020-0004; ADAMS STREET HOMES; PRELIMINARY GEOTECHNICAL INVESTIGATION FOR PROPOSED ADAMS STREET HOMES; 2020-09-14REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed Adams Street Homes 3745 Adams Street Carlsbad, California JOB NO. 20-12852 14 September 2020 Prepared for: Rincon Homes D ~~~•• G h . I I . ~,,..,., eotec . n1ca Exp oration, Inc. SOIL AND FOUNDATION ENGINEERING GROUNDWATER • ENGINEERING GEOLOGY 14 September 2020 Rincon Homes 5315 Avenida Encinitas, Suite 200 Carlsbad, CA 92008 Attn: Mr. Thomas St. Clair Job No. 20-12852 Subject: Report of Preliminary Geotechnical Investigation Proposed Adams Street Homes 3745 Adams Street Carlsbad, California Dear Mr. St. Clair: In accordance with your request, and our work agreement of July 10, 2020, Geotechnical Exploration, Inc. has performed a preliminary geotechnical investigation and infiltration testing for the subject project in Carlsbad, California. The field work was performed on August 03, 2020. If the conclusions and recommendations presented in this report are incorporated into the design and construction of the proposed four two-story, single family residences with attached garages, detached accessory dwelling units, and associated improvements, it is our opinion that the site is suitable for the proposed project. 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. 20-12852 will expedite a response to your inquiries. Respectfully submitted, CHNICAL EXPLORATION, INC. /G.E. 2007 Senior Geotechnical Engineer Leslie D. Reed, President C.E.G. 999/P.G. 3391 7420 TRADE STREET• SAN DIEGO, CA. 92121 • (858) 549-7222 e FAX: (858) 549-1604 • EMAIL: geotech@gei-sd.com TABLE OF CONTENTS I. PROJECT SUMMARY ............................................................................ 1 II. SCOPE OF WORK ................................................................................ 2 III. SITE DESCRIPTION ............................................................................. 2 IV. FIELD INVESTIGATION, OBSERVATIONS & SAMPLING .............................. 3 V. LABORATORY TESTING & SOIL INFORMATION ........................................ 4 VI. REGIONAL GEOLOGIC DESCRIPTION ..................................................... 6 VII. SITE-SPECIFIC SOIL & GEOLOGIC DESCRIPTION ................................... 10 VIII. GEOLOGIC HAZARDS ........................................................................ 12 A. Local and Regional Faults ........................................................... 12 B. Other Geologic Hazards ............................................................. 17 IX. GROUNDWATER ............................................................................... 20 X. CONCLUSIONS & RECOMMENDATIONS ................................................ 22 A. Preparation of Soils for Site Development ..................................... 23 B. Seismic Design Criteria .............................................................. 28 C. Foundation Recommendations .................................................... 29 D. Concrete Slab On-Grade Criteria ................................................. 31 E. Retaining Wall Design Criteria ..................................................... 35 F. Slopes .................................................................................... 38 G. Pavements .............................................................................. 39 H. Site Drainage Considerations ...................................................... 40 I. General Recommendations ......................................................... 41 XI. GRADING NOTES .............................................................................. 43 XII. LIMITATIONS ................................................................................... 43 REFERENCES FIGURES I. II. Illa-i. IVa-b. V. VI. Vicinity Map Plot Plan Exploratory Boring Logs and Laboratory Results Laboratory Test Results Geologic Map Excerpt and Legend Schematic Retaining Wall Subdrain Recommendations APPENDICES A. Unified Soil Classification System B. ASCE Seismic Summary Report REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed Adams Street Homes 3745 Adams Street Carlsbad, California JOB NO. 20-12852 The following report presents the findings and recommendations of Geotechnical Exploration, Inc. for the subject project. I. PROJECT SUMMARY It is our understanding, based on our communications with your architect, Kirk Moeller of Kirk Moeller Architects, Inc. that the existing single-family residential structure and associated improvements are to be entirely demolished and the site will be subdivided into four new individual lots. Each lot is proposed to receive a new single-family residential structure with attached garage, a new accessory dwelling unit, a new deck, retaining walls and associated improvements. A single bio- retention basin is proposed for the southwestern portion of the site. The new structures are to be constructed of standard-type building materials utilizing conventional foundations with either concrete slab on-grade or raised wood floors. Foundation loads are expected to be typical for this type of relatively light construction. A preliminary site plan by Kirk Moeller Architects, Inc., dated June 05, 2020, has been reviewed by us and used to understand the scope of the project. When final plans are completed, they should be made available for our review. Additional or modified recommendations will be provided at that time if warranted. Based on the available information at this stage, it appears that the proposed site development would not destabilize neighboring properties or induce the settlement of adjacent structures or improvements if designed and constructed in accordance with our recommendations. D Proposed Adams Street Homes Carlsbad, California II. SCOPE OF WORK Job No. 20-12852 Page 2 The scope of work performed for this investigation included a site reconnaissance and subsurface exploration program under the direction of our geologist with placement, logging and sampling of nine exploratory trenches, review of available published information pertaining to the site geology, 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, retaining walls, slab on-grade floors and associated improvements. III. SITE DESCRIPTION The lot is known as Assessor's Parcel No. 205-270-13-00, per Map No. 1681, in the City of Carlsbad, County of San Diego, State of California. For the purposes of this report, the existing residence is assumed to face eastward to Adams Street but, in fact, faces east-northeastward. Refer to Figure No. I, the Vicinity Map, for the site location. The rectangular shaped lot, consisting of 42,688 square feet, is bordered on the north by two single-family residential developments at roughly the same elevations; on the south by a single-family residential development and parking lot at roughly the same elevations; on the west by a school playground at a slightly lower elevation; and on the east by Adams Street at a slightly higher elevation. Refer to Figure No. II, the Plot Plan. Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 3 The existing property is currently developed with a two-story single-family residential structure and associated improvements. Vegetation on the site primarily consists of an ornamental garden, shrubbery, weeds, grasses and many mature trees. The property slopes from the eastern property line to the western property line. Approximate elevations across the property range from approximately 81 feet above Mean Sea Level (MSL) along the western property line of the site to 92 feet above MSL at the eastern property line. Survey information concerning elevations across the site was obtained from the topographic survey template of the preliminary site plan by Kirk Moeller Architects, Inc., dated June 05, 2020. IV. FIELD INVESTIGATION. OBSERVATIONS & SAMPLING The field investigation consisted of a surface reconnaissance and a subsurface exploration program utilizing a backhoe to investigate and sample the subsurface soils. Nine exploratory trenches (T-1 to T-9) were excavated to a maximum depth of 10 feet in the areas of the proposed development and associated improvements on August 03, 2020. The soils encountered in the exploratory trenches 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 trenches are shown on Figure No. II, the Plot Plan. Representative samples were obtained from the exploratory trenches at selected depths appropriate to the investigation. Relatively undisturbed chunk and drive samples and disturbed bulk samples were collected from the exploratory trenches to aid in classification and for appropriate laboratory testing. The samples were returned to our laboratory for evaluation and testing. Exploratory trench logs have D Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 4 been prepared on the basis of our observations and laboratory test results, and are attached as Figure Nos. Illa-i. The exploratory trench logs and related information depict subsurface conditions only at the specific locations shown on the plot plan and on the particular date designated on the logs. Subsurface conditions at other locations may differ from conditions occurring at the locations. Also, the passage of time may result in changes in subsurface conditions due to environmental changes. V. LABORATORY TESTING & SOIL INFORMATION Laboratory tests were performed on retrieved soil samples in order to evaluate their physical and mechanical properties. The test results are presented on Figure Nos. Illa-I and IVa-b. The following tests were conducted on representative soil samples: 1. Moisture Content (ASTM D2216-19) 2. Density Measurements (ASTM D2937-17e2) 3. Standard Test Method for Bulk Specific Gravity and Density of Compacted Bituminous Mixtures using Coated Samples (ASTM D1188-07) 4. Laboratory Compaction Characteristics (ASTM D1557-12e1) 5. Determination of Percentage of Particles Smaller than #200 Sieve (ASTM D1140-17) Moisture content and density measurements were performed by ASTM methods D2216-19 and D2937-17e2 respectively, in conjunction with D1188-07 to establish the in-situ moisture and density of samples retrieved from the exploratory trenches. Measurements were also performed by ASTM method D1188-07, the bulk specific gravity utilizing paraffin-coated specimens. This method helps to establish the in- situ density of chunk samples retrieved from formational exposures/outcrops. The Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 5 test results are presented on the trench logs at the appropriate sample depths and laboratory test results. Laboratory compaction values (ASTM D1557-12el) establish the optimum moisture content and the laboratory maximum dry density of the tested soils. The relationship between the moisture and density of remolded soil samples helps to establish the relative compaction of the existing fill soils and soil compaction conditions to be anticipated during any future grading operation. The test results are presented on the trench logs at the appropriate sample depths and laboratory test results. The particle size smaller than a No. 200 sieve analysis (ASTM D1140-17) aids in classifying the tested soils in accordance with the Unified Soil Classification System and provides qualitative information related to engineering characteristics such as expansion potential, permeability, and shear strength. The test results are presented on the trench logs at the appropriate sample depths and laboratory test results. The expansion potential of soils is determined, when necessary, utilizing the Standard Test Method for Expansion Index of Soils (ASTM D4829-19). In accordance with the 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 Hi qh Above 130 Very high Based on our visual classification and our past experience with similar soils, it is our opinion that the existing fill and formational materials of the Old Paralic Deposits, Units 2-4, encountered in the trenches possess a very low to low potential for D Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 6 expansion. Therefore, we have assigned a maximum expansion index of less than 50 to these soils. Based on the field and laboratory test data, our observations of the primary soil types, 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 that will have 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 and retaining walls. VI. REGIONAL GEOLOGIC DESCRIPTION San Diego County has been divided into three major geomorphic provinces: the Coastal Plain, the Peninsular Ranges and the Salton Trough. The Coastal Plain exists west of the Peninsular Ranges. The Salton Trough is east of the Peninsular Ranges. These divisions are the result of the basic geologic distinctions between the areas. Mesozoic metavolcanic, metasedimentary and plutonic rocks predominate in the Peninsular Ranges with primarily Cenozoic sedimentary rocks to the west and east of this central mountain range (Demere, 1997). In the Coastal Plain region, where the subject property is located, the "basement" consists of Mesozoic crystalline rocks. Basement rocks are also exposed as high relief areas (e.g., Black Mountain northeast of the subject property and Cowles Mountain near the San Carlos area of San Diego). Younger Cretaceous and Tertiary sediments lap up against these older features. These sediments form a "layer cake" sequence 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 :Ii Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 7 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 Range form the granitic spine of San Diego County. These rocks are primarily plutonic, forming at depth beneath the earth's crust 140 to 90 million years ago as the result of the subduction of an oceanic crustal plate beneath the North American continent. These rocks formed the much larger Southern California batholith. Metamorphism associated with the intrusion of these great granitic masses affected the much older sediments that existed near the surface over that period of time. These metasedimentary rocks remain as roof pendants of marble, schist, slate, quartzite and gneiss throughout the Peninsular Ranges. Locally, Miocene-age volcanic rocks and flows have also accumulated within these mountains (e.g., Jacumba Valley). Regional tectonic forces and erosion over time have uplifted and unroofed these granitic rocks to expose them at the surface (Demere, 1997). The Salton Trough is the northerly extension of the Gulf of California. This zone is undergoing active deformation related to faulting along the Elsinore and San Jacinto Fault Zones, which are part of the major regional tectonic feature in the southwestern portion of California, the San Andreas Fault Zone. Translational movement along these fault zones has resulted in crustal rifting and subsidence. The Salton Trough, also referred to as the Colorado Desert, has been filled with sediments to depth of approximately 5 miles since the movement began in the early Miocene, 24 million years ago. The source of these sediments has been the local mountains as well as the ancestral and modern Colorado River (Demere, 1997). 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 ;, Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 8 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, now the California Geological Survey, an "active" fault is one that has had ground surface displacement within Holocene time, about the last 11,000 years (Hart and Bryant, 1997). 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 defines a "potentially active" fault as one that has had ground surface displacement during Quaternary time, that is, between 11,000 and 1.6 million years (Hart and Bryant, 1997). During recent history, prior to April 2010, the San Diego County area has been relatively quiet seismically. No fault ruptures or major earthquakes had been experienced in historic time within the greater San Diego area. Since earthquakes have been recorded by instruments (since the 1930s), the San Diego area has experienced scattered seismic events with Richter magnitudes generally less than M4.0. During June 1985, a series of small earthquakes occurred beneath San Diego Bay, three of which were recorded at M4.0 to M4.2. In addition, the Oceanside earthquake of July 13, 1986, located approximately 26 miles offshore of the City of Oceanside, had a magnitude of M5.3 (Hauksson and Jones, 1988). Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 9 On June 15, 2004, a M5.3 earthquake occurred approximately 45 miles southwest of downtown San Diego (26 miles west of Rosarito, Mexico). Although this earthquake was widely felt, no significant damage was reported. Another widely felt earthquake on a distant southern California fault was a M5.4 event that took place on July 29, 2008, west-southwest of the Chino Hills area of Riverside County. Several earthquakes ranging from M5.0 to M6.0 occurred in northern Baja California, centered in the Gulf of California on August 3, 2009. These were felt in San Diego but no injuries or damage was reported. A M5.8 earthquake followed by a M4.9 aftershock occurred on December 30, 2009, centered about 20 miles south of the Mexican border city of Mexicali . These were also felt in San Diego, swaying high-rise buildings, but again no significant damage or injuries were reported. On April 4, 2010, a large earthquake occurred in Baja California, Mexico. It was widely felt throughout the southwest including Phoenix, Arizona and San Diego in California. This M7.2 event, the Sierra El Mayor earthquake, occurred in northern Baja California, approximately 40 miles south of the Mexico-USA border at shallow depth along the principal plate boundary between the North American and Pacific plates. According to the U. S. Geological Survey this is an area with a high level of historical seismicity, and it has recently also been seismically active, although 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. D Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 10 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. On July 7, 2010, a M5.4 earthquake occurred in Southern California at 4:53 pm (Pacific Time) about 30 miles south of Palm Springs, 25 miles southwest of Indio, and 13 miles north-northwest of Borrego Springs. The earthquake occurred near the Coyote Creek segment of the San Jacinto Fault. The earthquake exhibited right lateral slip to the northwest, consistent with the direction of movement on the San Jacinto Fault. The earthquake was felt throughout Southern California, with strong shaking near the epicenter. It was followed by more than 60 aftershocks of Ml.3 and greater during the first hour. 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: M5.8 in 1968, M5.3 on 2/25/1980, M5.0 on 10/31/2001, and M5.2 on 6/12/2005. The biggest earthquake near this location was the M6.0 Buck Ridge earthquake on 3/25/1937. VII. SITE-SPECIFIC SOIL & GEOLOGIC DESCRIPTION Our field investigation, reconnaissance and review of the geologic map by Kennedy and Tan, 2007, "Geologic Map of the Oceanside 30'x60' Quadrangle, California" indicate that the site is underlain at depth by late to middle Pleistocene-Aged Old Paralic Deposits, Units 2-4 (Qop2-4) formational materials. An excerpt of the geological map is included as Figure No. V. Our exploratory trenches indicate the Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 11 formational materials are overlain across the site by artificial fill soils (Qaf) and topsoil. Site-specific geology is mapped on Figure No. II, the Plot Plan. Fill Soil (Oaf): The site is overlain in previously graded areas by up to 7 feet of fill soil, which was encountered in trenches T-2 to T-6 and T-8 to T-9. The encountered fill soil consists of fine-to medium-grained, dry to moist, gray-brown to red-brown to brown to yellow-brown to light gray-brown, silty sands (SM) with variable amounts of roots, concrete, brick, and trash debris. The fill soils are loose to dense. In our opinion, due to the variable density and poor condition of the fill soil, it is not considered suitable in its current condition to support loads from structures or additional fill. Refer to Figure Nos. Illa-i for details. Topsoil: Topsoil was encountered underlying the fill soils in trenches T-1 to T-3, in trench T-7, and in undisturbed areas of the site at existing grade. The encountered topsoil consists of dry, brown to dark-brown, silty sands (SM) with variable amounts of roots. The topsoil is loose to medium dense. In our opinion, due to the variable and low density of the topsoil, it is not considered suitable in its current condition to support loads from structures or additional fill. Refer to Figure Nos. IIIa-i for details. Old Paralic Deposits, Unit 2-4 (Oop2-4}_;__ Formational materials of Old Paralic Deposits, Units 2-4 were encountered in all trenches underlying the fill soil and topsoil at variable depths from 1.5 to 9 feet. The formational materials consist of fine-to medium-grained, damp to wet, red-brown silty sands (SM) with areas of moderate cementation and some roots. The formational materials underlying the site are medium dense to dense. In our opinion, the medium dense to dense nature of the Old Paralic Deposits, Units 2-4, makes it suitable in its current condition to support loads from structures or additional fill. Refer to Figure Nos. IIIa-i for details. Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 12 Based on our review of the geologic map by Kennedy and Tan, 2007, "Geologic Map of the Oceanside 30'x60' Quadrangle, California" the Old Paralic Deposits, Units 2-4, formational materials underlie the entire site at depth. The aforementioned Old Paralic Deposit Units are described as "Poorly sorted, moderately permeable, reddish- brown, interfingered strandline, beach, estuarine and colluvial deposits composed of siltstone, sandstone and conglomerate." According to the map, there are no faults known to pass through the site (refer to Figure No. V, Geologic Map Excerpt and Legend). VIII. GEOLOGIC HAZARDS The following is a discussion of the geologic conditions and hazards common to this area of Carlsbad, as well as project-specific geologic information relating to development of the subject site. A. Local and Regional Faults Reference to the Geologic Map and Legend, Figure No. V (Kennedy and Tan, 2007), indicates that no faults are shown to cross the site. In our explicit professional opinion, neither an active fault nor a potentially active fault underlies the site. Rose Canyon Fault: The Rose Canyon Fault Zone (Mount Soledad and Rose Canyon Faults) is mapped approximately 5.3 miles southwest of the 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 D Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 13 is considered microseismically active, although no significant recent earthquakes since 1769 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 and Bryant, 1997). Rockwell (2010) has suggested that the RCFZ underwent a cluster of activity including 5 major earthquakes in the early Holocene, with a long period of inactivity following, suggesting major earthquakes on the RCFZ behaves in a cluster-mode, where earthquake recurrence is clustered in time rather than in a consistent recurrence interval. With the most recent earthquake (MRE) nearly 500 years ago, it is suggested that a period of earthquake activity on the RCFZ may have begun. Rockwell (2010) and a compilation of the latest research implies a long-term slip rate of approximately 1 to 2 mm/year. Coronado Bank Fault: The Coronado Bank Fault is located approximately 21.3 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 et al., 1979). The Oceanside earthquake of M5.3 recorded July 13, 1986, is known to have been centered on the fault or within the Coronado Bank Fault Zone. Although this fault is considered active, due to the seismicity within the fault zone, it is significantly less active seismically than the Elsinore Fault (Hileman et al., 1973). It is postulated that the Coronado Bank Fault is capable of generating a M7.6 111 Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 14 earthquake and is of great interest due to its close proximity to the greater San Diego metropolitan area. Newport-Inglewood Fault: The offshore portion of the Newport-Inglewood Fault Zone is located approximately 5.7 to 46.2 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 (Grant Ludwig and Shearer, 2004 ). Elsinore Fault: The Elsinore Fault is located approximately 24 to 58 miles east and northeast of the site. The fault extends approximately 200 km (125 miles) from the Mexican border to the northern end of the Santa Ana Mountains. The Elsinore Fault zone is a 1-to 4-mile-wide, northwest-southeast-trending zone of discontinuous and en echelon faults extending through portions of Orange, Riverside, San Diego, and Imperial Counties. Individual faults within the Elsinore Fault Zone range from less than 1 mile to 16 miles in length. The trend, length and geomorphic expression of the Elsinore Fault Zone identify it as being a part of the highly active San Andreas Fault system. Like the other faults in the San Andreas system, the Elsinore Fault is a transverse fault showing predominantly right-lateral movement. According to Hart et al. (1979), this movement averages less than 1 centimeter per year. Along most of its length, the Elsinore Fault Zone is marked by a bold topographic expression consisting of linearly aligned ridges, swales and hallows. Faulted Holocene alluvial deposits (believed to be less than 11,000 years old) found along several segments of the fault zone suggest that at least part of the zone is currently active. 91 Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 15 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 with a magnitude as large as M7.5. Study and logging of exposures 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 earthquake magnitudes of M6.0 to M7.0 (Rockwell et al., 1985). The Working Group on California Earthquake Probabilities (2008) has estimated that there is a 11 percent probability that an earthquake of M6. 7 or greater will occur within 30 years on this fault. San Jacinto Fault: The San Jacinto Fault is located approximately 46 to 66 miles 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 (Rockwell et al., 2014). 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- Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 16 lateral, similar to the San Andreas Fault, although some investigators have suggested that dip-slip motion contributes up to 10% of the net slip (Ross et al., 2017). 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 (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. 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 area on June 12th at 8:08 pm (Pacific Time). Thus this section of the San Jacinto fault remains active. Bi Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 17 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. B. Other Geologic Hazards Ground Rupture: Ground rupture is characterized by bedrock slippage along an established fault and may result in displacement of the ground surface. For ground rupture to occur along a fault, an earthquake usually exceeds MS.0. If a MS.0 earthquake 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. Ground Shaking: Structural damage caused by seismically induced ground shaking is a detrimental effect directly related to faulting and earthquake activity. Ground shaking is considered to be the greatest seismic hazard in San Diego County. The intensity of ground shaking is dependent on the magnitude of the earthquake, the distance from the earthquake, and the seismic response characteristics of underlying soils and geologic units. Earthquakes of MS.0 or greater are generally associated Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 18 with significant damage. It is our opinion that the most serious damage to the site would be caused by a large earthquake originating on a nearby strand of the Rose Canyon, Coronado Bank or Newport-Inglewood Faults. Although the chance of such an event is remote, it could occur within the useful life of the structure. Landslides: Our investigation indicates that the subject site is not directly on a known recent or ancient landslide. Review of the "Geologic Map of the Oceanside 30'x60' Quadrangle, California" by Kennedy and Tan (2007), and United States Department of Agriculture stereo pair aerial photographs AXN-14M-19 and 20 (1953) indicate there are no known or suspected ancient landslides located on the site. Slope Stability: We have performed a site reconnaissance and the site gently slopes in a southwest direction, with only an 11-foot difference in elevation across the area of the site. The site is underlain by relatively stable Old Paralic Deposits, Unit 2-4 formational materials at a depth of 1.5 to 9 feet. There is not a slope stability issue with the site. Liquefaction: The liquefaction of saturated sands during earthquakes can be a major cause of damage to buildings. Liquefaction is the process by which soils are transformed into a viscous fluid that will flow as a liquid when unconfined. It occurs primarily in loose, saturated sands and silts when they are sufficiently shaken by an earthquake. On this site, the risk of liquefaction of formational materials due to seismic shaking is considered to be very low due to the medium dense to dense nature of the underlying formational materials and minimal amount of shallow static groundwater. The site does not have a potential for soil strength loss to occur due to a seismic event. ;, Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 19 Tsunamis and Seiches: 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, meteor 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 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 more than 3,000 feet inland. The site is located approximately 0.8-mile from the exposed coastline and at an elevation of approximately 81 to 92 feet MSL. There is no risk of tsunami inundation at the site. A seiche is a run-up of water within a lake or embayment triggered by fault-or landslide-induced ground displacement. There are no significant bodies of water located at higher elevation or in the general vicinity capable of producing a seiche and inundating the subject site. 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 at shallow depth by stable Old Paralic Deposits formational materials and is suited for the proposed residential structures, ADUs, retaining walls and associated improvements provided the recommendations herein are implemented. Furthermore, based on the available information at this stage, it appears the proposed site development will not Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 20 destabilize or result in settlement of adjacent property or improvements if the recommendations presented in this report are implemented. No significant geologic hazards are known to exist on the site that would prohibit the construction of the proposed residential structures, ADUs, retaining walls and associated improvements. 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. IX. GROUNDWATER Minor groundwater seepage was only encountered in trench T-5 at a depth of 5 feet below existing grade during the field investigation. 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. It should be kept in mind that any required construction operations will change surface drainage patterns and/or reduce permeabilities due to the densification of compacted soils. Such changes of surface and subsurface hydrologic conditions, plus irrigation of landscaping or significant increases in rainfall, may result in the appearance of surface or near-surface water at locations where none existed previously. The damage from such water is expected to be localized and cosmetic in Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 21 nature, if good positive drainage is implemented, as recommended in this report, during and at the completion of construction. On properties such as the subject site where dense, low permeability soils exist at shallow depths, even normal landscape irrigation practices on the property or neighboring properties, or periods of extended rainfall, can result in shallow "perched" water conditions. The perching (shallow depth) accumulation of water on a low permeability surface can result in areas of persistent wetting and drowning of lawns, plants and trees. Resolution of such conditions, should they occur, may require site-specific design and construction of subdrain and shallow "wick" drain dewatering systems. Subsurface drainage with a properly designed and constructed subdrain system will be required along with continuous back drainage behind any proposed lower-level basement walls, property line retaining walls, or any perimeter stem walls for raised- wood floors where the outside grades are higher than the crawl space grades. Furthermore, crawl spaces, if used, should be provided with the proper cross- ventilation to help reduce the potential for moisture-related problems. Additional recommendations may be required at the time of construction. It must be understood that unless discovered during site exploration or encountered during site construction operations, it is extremely difficult to predict if or where perched or true groundwater conditions may appear in the future. When site fill or formational soils are fine-grained and of low permeability, water problems may not become apparent for extended periods of time. Water conditions, where suspected or encountered during construction, should be evaluated and remedied by the project civil and geotechnical consultants. The project developer and property owner, however, must realize that post-construction ~ Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 22 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 & RECOMMENDATIONS The following recommendations are based upon the practical field investigations conducted by our firm, and resulting laboratory tests, in conjunction with our knowledge and experience with similar soils in the Carlsbad area. The opinions, conclusions, and recommendations presented in this report are contingent upon Geotechnical Exploration, Inc. being retained to review the final plans and specifications as they are developed and to observe the site earthwork and installation of foundations. Accordingly, we recommend that the following paragraph be included on the grading and foundation plans for the project. If the geotechnical consultant of record is changed for the project, the work shall be stopped until the replacement has agreed in writing to accept 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 governing agency in writing of such change prior to the recommencement of grading and/or foundation installation work and comply with the governing agency's requirements for a change to the Geotechnical Consultant of Record for the project. We recommend that the planned residential structures, garages, ADUs, decks, and retaining walls be supported by conventional, individual-spread and/or continuous footing foundations founded on medium dense to dense formational soils and minimum 90 percent compacted structural fill soils. Individual structures may bear on formational or fill soils depending on their locations, final grading elevations and exposure of formational materials. Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 23 Existing fill soils across the entire site will be disturbed during the demolition of the existing residence, and are not suitable in their current condition to support new structures or associated improvements. A full removal and recompaction of existing fill and top soils across the site will be required to support the proposed structures and associated improvements. Fill soils across the site will be required to be compacted to at least 90 percent relative compaction. Existing fill soil and formational materials are suitable for use as recompacted fill soils. Any buried trash and roots encountered during site demolition and fill soil recompaction should be removed and exported off site. It is our opinion that the site is suitable for the planned residential project provided the recommendations herein are incorporated during design and construction. A. Preparation of Soils for Site Development 1. Clearing and Stripping: Complete demolition of the existing residential structure and associated improvements should be undertaken. This is to include the complete removal of all subsurface footings, utility lines and miscellaneous debris. After clearing the entire ground surface of the site should be stripped of existing vegetation within the areas of proposed new construction. 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 suitable compacted material compacted to the requirements provided under Recommendation Nos. 3, 4 and 5 below. Prior to any filling operations, the cleared and stripped vegetation and debris should be disposed of off-site. Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 24 2. Excavation: After the entire site has been cleared and stripped, all of the existing fill soils and topsoil should be removed and recompacted. The depth of removals across the site will vary depending on the thickness of unsuitable soils overlying the formational materials. It is anticipated that the depth of removals will be up to 9 feet below existing grade in the area of the existing house pad, however shallower removals should be anticipated across the remainder of the site. Based on the results of our exploratory trenches and test holes, as well as our experience with similar materials in the project area, it is our opinion that the existing fill soils and topsoil materials can be excavated utilizing ordinary light to heavy weight earthmoving equipment. Contractors should not, however, be relieved of making their own independent evaluation of excavating the on-site materials prior to submitting their bids. Contractors should also review this report along with the trench logs to understand the scope and quantity of grading required for this project. Variability in excavating the subsurface materials should be expected across the project area. The areal extent required to remove the surficial soils should be confirmed by our representatives during the excavation work based on their examination of the soils being exposed. The lateral extent of the excavation and recompaction should be at least 5 feet beyond the edge of the perimeter ground level foundations of the new residential structure and any areas to receive exterior improvements, where feasible, or to the depth of excavation or fill at that location, whichever is greater. New structures should not bear on a cut-fill transition. If a cut-fill transition exists at footing bearing level elevation, then an undercut of at least 12 inches below bearing elevation and recompaction of the entire envelope of the Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 25 structure will be required. Furthermore, no structures should be supported on a building pad with structural fill soil thickness differential of greater than 5 feet. 3. Subgrade Preparation: After the site has been cleared, stripped, and the required excavations made, the exposed subgrade soils in areas to receive new fill and/or slab-on-grade building improvements should be scarified to a depth of 6 inches, moisture conditioned, and compacted to the requirements for structural fill. While not anticipated, in the event that planned cuts expose any medium to highly expansive formational materials in the building areas, they should be scarified and moisture conditioned to at least 5 percent over optimum moisture. 4. Material for Fill: Existing on-site low-expansion potential (Expansion Index of 50 or less per ASTM D4829-19) 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. 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. If encountered at the site, medium to highly expansive soils should not be used as structural fill at a depth of less than 5 feet from footing bearing surface elevation or behind retaining walls. Backfill material to be placed behind retaining walls should be low expansive (E.I. less than 50), with rocks no larger than 3 inches in diameter. ti& Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 26 5. Structural Fill Compaction: All structural fill, and areas to receive any associated improvements, should be compacted to a minimum degree of compaction of 90 percent based upon ASTM D1557-12el. 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. Though we do not anticipate any medium to high expansive soils to be exposed during grading operations, if encountered, the compaction moisture content should be at least 5 percent over optimum. Any rigid improvements founded on the existing undocumented fill soils can be expected to undergo movement and possible damage. Geotechnical Exploration, Inc. takes no responsibility for the performance of any improvements built on loose natural soils or inadequately compacted fills. Subgrade soils in any exterior area receiving concrete improvements should be verified for compaction and moisture by a representative of our firm within 48 hours prior to concrete placement. No uncontrolled fill soils should remain after completion of the site work. In the event that temporary ramps or pads are constructed of uncontrolled fill soils, the loose fill soils should be removed and/or recompacted prior to completion of the grading operation. • Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 27 6. Trench and Retaining Wall Backfill: All utility trenches and retaining walls should be backfilled with properly compacted fill. Backfill material should be placed in lift thicknesses appropriate to the type of compaction equipment utilized and compacted to a minimum degree of compaction of 90 percent based upon ASTM D1557-12e1 by mechanical means. Any portion of the trench backfill in public street areas within pavement sections should conform to the material and compaction requirements of the adjacent pavement section. Backfill soils placed behind retaining walls should be installed as early as the retaining walls are capable of supporting lateral loads. Backfill soils behind retaining walls should be low expansive (Expansion Index less than 50 per ASTM D4829-19). 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. 7. Observations and Testing: It is mandatory that a representative of this firm perform observations and fill compaction testing during excavation operations to verify that the remedial operations are consistent with the recommendations presented in this report. All grading excavations resulting from the removal of soils should be observed and evaluated by a representative of our firm before they are backfilled. D Proposed Adams Street Homes Carlsbad, California B. Seismic Design Criteria Job No. 20-12852 Page 28 8. Seismic Data Bases: The estimation of the peak ground acceleration and the repeatable high ground acceleration (RHGA) likely to occur at the site is based on the known significant local and regional faults within 100 miles of the site. 9. Seismic Design Criteria: The proposed structure should be designed in accordance with the 2019 CBC, which incorporates by reference the ASCE 7- 16 for seismic design. We have determined the mapped spectral acceleration values for the site based on a latitude of 33.1550 degrees and a longitude of-117.3357 degrees, utilizing a program titled "Seismic Design Map Tool" and provided by the USGS through SEAOC, which provides a solution for ASCE 7- 16 utilizing digitized files for the Spectral Acceleration maps. See Appendix B. 10. Structure and Foundation Design: The design of the new structures and foundations should be based on Seismic Design Category D, Risk Category II for a Site Class Stiff Soils D. 11. Spectral Acceleration and Design Values: The structural seismic design, when applicable, should be based on the following values, which are based on the site location, soil characteristics, and seismic maps by USGS, as required by the 2019 CBC. The summarized seismic soil parameters are presented in table I below, have been calculated with the SEAOC Seismic Design Map Tool. The complete values are included in Appendix B. The Site Class Stiff Soil D values for this property are: Bi Proposed Adams Street Homes Carlsbad, California TABLE I Job No. 20-12852 Page 29 Mapped Spectral Acceleration Values and Design Parameters Ss Fa Fv Sms 1.059 0.384 1.20 1.92 1.271 C. Foundation Recommendations 12. Footings: We recommend that the proposed structures be supported on conventional, individual-spread and/or continuous footing foundations bearing on undisturbed formational materials or on properly compacted fill soils over formational soils. No footings should be underlain by undocumented fill soils. All building footings should be built on formational soils or properly compacted fill prepared as recommended above in Recommendation Nos. 3, 4 and 5. The footings should be founded at least 18 inches below the lowest adjacent finished grade when founded into properly compacted fill or formational soils. Footings located adjacent to utility trenches should have their bearing surfaces situated below an imaginary 1.0: 1.0 plane projected upward from the bottom edge of the adjacent utility trench. Otherwise, the utility trenches should be excavated farther from the footing locations. Footings located adjacent to the tops of slopes should be extended sufficiently deep so as to provide at least 8 feet of horizontal cover between the slope face and outside edge of the footing at the footing bearing level. 13. Bearing Values: At the recommended depths, footings on formational or properly compacted fill soils may be designed for allowable bearing pressures of 2,500 pounds per square foot (psf) for combined dead and live loads and 3,300 psf for all loads, including wind or seismic. The footings should, Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 30 however, have a minimum width of 18 inches. An increase in soil allowable static bearing can be used as follows: 800 psf for each additional foot over 1.5 feet in depth and 400 psf for each additional foot in width to a total not exceeding 4,500 psf. The static soil bearing value may be increased one-third for seismic and wind load analysis. As previously indicated, all of the foundations for the building should be built on dense formational soils or properly compacted fill soils. 14. Footing Reinforcement: All continuous footings should contain top and bottom reinforcement to provide structural continuity and to permit spanning of local irregularities. We recommend that a minimum of two No. 5 top and two No. 5 bottom reinforcing bars be provided in the footings. All footings 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 forms. 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. 15. Lateral Loads: Lateral load resistance for the structure supported on footing foundations may be developed in friction between the foundation bottoms and the supporting subgrade. An allowable friction coefficient of 0.40 is considered Ui Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 31 applicable. An additional allowable passive resistance equal to an equivalent fluid weight of 300 pounds per cubic foot (pcf) acting against the foundations may be used in design provided the footings are poured neat against the dense formational or properly compacted fill materials. These lateral resistance value assume a level surface in front of the footing for a minimum distance of three times the embedment depth of the footing and any shear keys, but not less than 8 feet from a slope face, measured from effective top of foundation. Retaining walls supporting surcharge loads or affected by upper foundations should consider the effect of those upper loads. 16. Settlement: Settlements under structural design loads are expected to be within tolerable limits for the proposed structures. 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. D. Concrete Slab On-Grade Criteria Slabs on-grade may only be used on new, properly compacted fill or when bearing on dense formational soils. 17. 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. D Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 32 New interior floor slabs should be a minimum of 5 inches actual thickness and be reinforced with No. 4 bars on 18-inch centers, both ways, placed at mid- height in the slab. Soil moisture content should be kept above the optimum prior to waterproofing placement under the new concrete slab. We note that shrinkage cracking can result in reflective cracking in brittle flooring surfaces such as stone and tiles. It is imperative that if movement intolerant flooring materials are to be utilized, the flooring contractor and/or architect should provide specifications for the use of high-quality isolation membrane products installed between slab and floor materials. 18. 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. It is recommended to contact the vapor barrier manufacturer to schedule a pre-construction meeting and to coordinate a review, in-person or digital, of the vapor barrier installation. 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. IP Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 33 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 745-17 Standard Specification for Plastic Water Vapor Retarders Used in Contact Concrete Slabs; ASTM E1643- 18a Standard Practice for Selection, Design, Installation, and Inspection of Water Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs; ACI 302.2R-06 Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials; and ACI 302.lR-15 Guide to Concrete Floor and Slab Construction. 18.1 Based on the above, we recommend that the vapor barrier consist of a minimum 15-mil extruded polyolefin plastic (no recycled content or woven materials permitted). Permeance as tested before and after mandatory conditioning (ASTM El 745 Section 7 .1 and subparagraphs 7.1.1-7.1.5) should be less than 0.01 perms (grains/square foot/hour/per inch of Mercury) and comply with the ASTM E1745-17 Class A requirements. Installation of vapor barriers should be in accordance with ASTM E1643-18a. The basis of design is 15-mil Stego Wrap 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 properly compacted smooth subgrade soil surface. 81 Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 34 18.2 Common to all acceptable products, vapor retarder/barrier joints must be lapped at least 6 inches. Seam joints and permanent utility penetrations should be sealed with the manufacturer's recommended tape or mastic. Edges of the vapor retarder should be extended to terminate at a location in accordance with ASTM E1643-18a or to an alternate location that is acceptable to the project's structural engineer. All terminated edges of the vapor retarder should be sealed to the building foundation (grade beam, wall, or slab) using the manufacturer's recommended accessory for sealing the vapor retarder to pre-existing or freshly placed concrete. Additionally, 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. Vapor barrier-safe screeding and forming systems should be used that will not leave puncture holes in the vapor barrier, such as Beast Foot (by Stego Industries) or equivalent. 18.3 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. Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 35 18.4 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. 19. Exterior Slab Thickness and Reinforcement: As a minimum for protection of on-site improvements, we recommend that all exterior pedestrian concrete slabs be 4 inches thick and be founded on properly compacted and tested fill, with No. 3 bars at 15-inch centers, both ways, at the center of the slab, and 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 without our observation and testing. 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 joints in exterior slabs should be sealed with elastomeric joint sealant. The sealant should be inspected every 6 months and be properly maintained. E. Retaining Wall Design Criteria 20. Design Parameters -Unrestrained: The active earth pressure to be utilized in the design of any cantilever site retaining walls, utilizing on-site low-expansive [EI less than 50] or imported very low-to low-expansive soils [EI less than 50] as backfill should be based on an Equivalent Fluid Weight of 38 pcf (for Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 36 level backfill only). For 2.0: 1.0 sloping backfill, the cantilever site retaining walls should be designed with an equivalent fluid pressure of 52 pcf. Unrestrained retaining walls should be backfilled with very low to low expansive soils. Unrestrained building retaining walls should be designed for 38 pcf for level low expansive soil backfill, and use a conversion load factor of 0.31 for vertical surcharge loads to be converted to uniform lateral surcharge loads. Temporary cantilever shoring walls may use 45 pcf active pressure, and a conversion factor of 0.36 to convert vertical uniform surcharge to horizontal uniform pressure. For passive resistance, use the value of 750 pcf times the diameter of the soldier pile, times the depth of embedment below the grade excavation in front of the piles. 21. Design Parameters -Restrained: Temporary or permanent site restrained shoring walls or restrained building retaining walls supporting low expansive level backfill may utilize a triangular pressure increasing at a rate of 56 pcf for wall design (78 pcf for sloping 2.0: 1.0 backfill). The soil pressure produced by any footings, improvements, or any other surcharge placed within a horizontal distance equal to the height of the retaining portion of the wall should be included in the wall design pressure. A conversion factor of 0.47 pcf may be used to convert vertical uniform surcharge loads to lateral uniform pressure behind a restrained retaining wall with level backfill and 0.64 when supporting a 2 to 1 sloping backfill. The recommended lateral soil pressures are based on the assumption that no loose soils or unstable soil wedges will be retained by the retaining wall. Backfill soils should consist of low-expansive soils with EI less than 50, and should be placed from the heel of the foundation to the ground surface within the wedge formed by a plane at 30° from vertical, and passing by the heel of the foundation and the back face of the retaining wall. Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 37 22. Retaining Wall Seismic Design Pressures: For seismic design of unrestrained walls over 6 feet in exposed height, we recommend that the seismic pressure increment be taken as a fluid pressure distribution utilizing an equivalent fluid weight of 15 pcf. This seismic increment is waived for restrained basement walls. If the walls are designed as unrestrained walls, then the seismic load should be added to the static soil pressure. 23. Basement/Retaining Wall Drainage: 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 that drainage be provided by a composite drainage material such as J-Drain 200/220 and J-Drain SWD, or equivalent. No perforated pipes or gravel are utilized with the J-Drain system. The drain material should terminate 12 inches below the exterior finish surface where the surface is covered by slabs or 18 inches below the finish surface in landscape areas (see Figure No. VI for Schematic Retaining Wall Subdrain Recommendations). Waterproofing should extend from the bottom to the top of the wall. Backfill placed behind retaining 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. Crushed rock gravel may only be used as backfill in areas where access is too narrow to place compacted soils. Behind shoring walls sand slurry backfill may be used behind lagging. Geotechnical Exploration, Inc. will assume no liability for damage to structures or improvements that is attributable to poor drainage. The architectural plans should clearly indicate that subdrains for any lower-level Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 38 walls be placed at an elevation at least 1 foot below the bottom of the lower- level slabs. F. Slopes 24. Temporary Slopes: Based on our subsurface investigation work, laboratory test results, and engineering analysis, temporary cut slopes up to 12 feet in height in the formational materials should be stable from mass instability at an inclination 0. 75 : 1.0 (horizontal to vertical). Temporary cut slopes up to 12 feet in height in fill soils should be stable against mass instability at an inclination of 1.5: 1.0. Some localized sloughing or raveling of the soils exposed on the slopes may occur. Since the stability of temporary construction slopes will depend largely on the contractor's activities and safety precautions (storage and equipment loadings near the tops of cut slopes, surface drainage provisions, etc.), it should be the contractor's responsibility to establish and maintain all temporary construction slopes at a safe inclination appropriate to the methods of operation. No soil stockpiles or surcharge may be placed within a horizontal distance of 10 feet or the depth of the excavation, whichever is larger, from the excavation top. If these recommendations are not feasible due to space constraints, temporary shoring may be required for safety and to protect adjacent property improvements. Similarly, footings near temporary cuts should be underpinned or protected with shoring. 111 Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 39 25. Slope Observations: A representative of Geotechnica/ Exploration, Inc. must observe any steep temporary slopes during construction. In the event that soils and formational material comprising a slope are not as anticipated, any required slope design changes would be presented at that time. 26. Permanent Slopes: Any new or existing cut or fill slopes up to 10 feet in height should be constructed at an inclination of 2.0: 1.0 (horizontal to vertical), be provided with a keyway at least 2 feet in depth and at least 8 feet in width for the entire length of the slope. Permanent slopes at a 2.0: 1.0 slope ratio should possess a factor of safety of 1.5 against deep and shallow failure. G. Pavements 27. Concrete Pavement: We recommend that driveways subject only to automobile and light truck traffic be 5.5 inches thick and be supported directly on properly prepared/compacted on-site subgrade soils. The upper 6 inches of the subgrade below the slab should be compacted to a minimum degree of compaction of 95 percent just prior to paving. The concrete should conform to Section 201 of The Standard Specifications for Public Works Construction, 2015 Edition, for Class 560-C-3250. In order to control shrinkage cracking, we recommend that saw-cut, weakened-plane joints be provided at about 15-foot centers both ways and at reentrant corners. The pavement 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-feet. Reinforcing steel is not necessary unless it is desired to increase the joint spacing recommended above. r, Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 40 28. Interlocking Permeable Pavers: If desired, we recommend that permeable pavement pavers for the driveway, subject only to automobile and light truck traffic, be supported on a 1.5 inches of bedding sand No. 8 Sand, on 6-inch thickness of Crushed Miscellaneous Base conforming to Section 200-2 of the Standard Specifications for Public Works Construction, 2018 Edition; or 6 inches of No.57 crushed rock gravel per ASTM D448 gradation . The upper 6 inches of the pavement subgrade soil as well as the aggregate base layer should be compacted to a minimum degree of compaction of 95 percent. Preparation of the subgrade and placement of the base materials should be performed under the observation of our representative. H. Site Drainage Considerations 29. 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. 30. 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. ;, Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 41 Failure to observe this recommendation could result in undermining and possible differential settlement of the structure or other improvements on the site or cause other moisture-related problems. Currently, the CBC requires a minimum 1-percent surface gradient for proper drainage of building pads unless waived by the building official. Concrete pavement may have a minimum gradient of 0.5-percent. 31. Planter Drainage: Planter areas, flower beds and planter boxes should be sloped to drain away from the footings and floor slabs at a gradient of at least 5 percent within 5 feet from the perimeter walls. Any planter areas adjacent to the residence or surrounded by concrete improvements should be provided with sufficient area drains to help with rapid runoff disposal. No water should be allowed to pond adjacent to the residence or other improvements or anywhere on the site. 32. Drainage Quality Control: It must be understood that 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 (if needed), drain depth below interior floor or yard surface, pipe percent slope to the outlet, etc. I. General Recommendations 33. Pro;ect 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 Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 42 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.). 34. Cal-OSHA: Where not superseded by specific recommendations presented in this report, trenches, excavations, and temporary slopes at the subject site should be constructed in accordance with Title 8, Construction Safety Orders, issued by Cal-OSHA. 35. Construction Best Management Practices (BMPs): Construction BMPs must be implemented in accordance with the requirements of the controlling jurisdiction. Sufficient BMPs must be installed to prevent silt, mud or other construction debris from being tracked into the adjacent street(s) or storm water conveyance systems due to construction vehicles or any other construction activity. The contractor is responsible for cleaning any such debris that may be in the street at the end of each work day or after a storm event that causes breach in the installed construction BMPs. All stockpiles of uncompacted soil and/or building materials that are intended to be left unprotected for a period greater than 7 days are to be provided with erosion and sediment controls. Such soil must be protected each day when the probability of rain is 40% or greater. A concrete washout should be 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 Bi Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 43 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 Geotechnical 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 and general contractor to comply with the requirements on the grading plans as well as the local grading ordinance. All retaining wall and trench backfill should be properly compacted. Geotechnical Exploration, Inc. will assume no liability for damage occurring due to improperly or uncompacted backfill placed without our observations and testing. XII. LIMITATIONS Our conclusions and recommendations have been based on available data obtained from our field investigation and laboratory analysis, as well as our experience with similar soils and formational materials located in this area of Carlsbad. Of necessity, we must assume a certain degree of continuity between exploratory excavations and/or natural exposures. It is, therefore, necessary that all observations, conclusions, and recommendations be verified at the time grading operations begin Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 44 or when footing excavations are placed. In the event discrepancies are noted, additional recommendations may be issued, if required. The work performed and recommendations presented herein are the result of an investigation and analysis that meet the contemporary standard of care in our profession within the County of San Diego. No warranty is provided. As stated previously, it is not within the scope of our services to provide quality control oversight for surface or subsurface drainage construction or retaining wall sealing and base of wall drain construction. It is the responsibility of the contractor to verify proper wall sealing, geofabric installation, protection board installation (if needed), drain depth below interior floor or yard surfaces; pipe percent slope to the outlet, etc. This report should be considered valid for a period of two (2) years, and is subject to review by our firm following that time. If significant modifications are made to the building plans, especially with respect to the height and location of any proposed structures, this report must be presented to us for immediate review and possible revision. It is the responsibility of the owner and/or developer to ensure that the recommendations summarized in this report are carried out in the field operations and that our recommendations for design of this project are incorporated in the project 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. Proposed Adams Street Homes Carlsbad, California Job No. 20-12852 Page 45 This firm does not practice or consult in the field of safety engineering. We do not direct the contractor's operations, and we cannot be responsible for the safety of personnel other than our own on the site; the safety of others is the responsibility of the contractor. The contractor should notify the owner if any of the recommended actions presented herein are considered to be unsafe. The firm of Geotechnical Exploration, Inc. shall not be held responsible for changes to the physical condition of the property, such as addition of fill soils or changing drainage patterns, which occur subsequent to issuance of this report and the changes are made without our observations, testing, and approval. Once again, should any questions arise concerning this report, please feel free to contact the undersigned. Reference to our Job No . 20-12852 will expedite a reply to your inquiries. Respectfully submitted, CHNICAL EXPLORATION, INC. Jaim R .. E. 34422/G.E. 2007 Senior Geotechnical Engineer ~ ~ Staff Geologist Leslie D. Reed, President C.E.G. 999/P.G. 3391 REFERENCES JOB NO. 20-12852 September 2020 2007 Working Group on California Earthquake Probabilities, 2008, The Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2), U.S Geological Survey Open-file Report 2007-1437 and California Geological Survey Special Report 203. Association of Engineering Geologists, 1973, Geology and Earthquake Hazards, Planners Guide to the Seismic Safety Element, Association of Engineering Geologists, Southern California Section. Berger, V. and Schug, D.L., 1991, Probabilistic Evaluation of Seismic Hazard in the San Diego-Tijuana Metropolitan Region, Environmental Perils, San Diego Region, Geological Society of America by the San Diego Association of Geologists, October 20, 1991, p. 89-99. Crowell, J.C., 1962, Displacement Along the San Andreas, Fault, California, Geological Society of America, Special Papers, no. 71. Demere, T.A. 1997, Geology of San Diego County, California, San Diego Natural History Museum, http://archive.sdnhm.org/research/paleontology/sdgeol.html, accessed July 30, 2020. Grant Ludwig, L.B. and Shearer, P.M., 2004, Activity of the Offshore Newport-Inglewood Rose Canyon Fault Zone, Coastal Southern California, from Relocated Microseismicity. Bulletin of the Seismological Society of America, 94(2), 747-752. Greene, H.G., Bailey, K.A., Clarke, S.H., Ziony, J.I. and Kennedy, M.P., 1979, Implications of fault patterns of the inner California continental borderland between San Pedro and San Diego, in Abbott, P.L., and Elliot, W.J., eds., Earthquakes and other perils, San Diego region: San Diego Association of Geologists, Geological Society of America field trip, November, 1979, p. 21-28. Greensfelder, R.W., 1974, Maximum Credible Rock Accelerations from Earthquakes in California, California Division of Mines and Geology. Hart E.W. and Bryant, W.A., 1997, Fault-Rupture Hazard Zones in California, California Division of Mines and Geology, Special Publication 42. Hart, E.W., Smith, D.P. and Saul, R.B., 1979, Summary Report: Fault Evaluation Program, 1978 Area (Peninsular Ranges-Salton Trough Region), California Division of Mines and Geology, Open-file Report 79-10 SF, 10. Hauksson, E. and Jones, L.M., 1988, The July 1986 Oceanside (ML=5.3) Earthquake Sequence in the Continental Borderland, Southern California Bulletin of the Seismological Society of America, v. 78, p. 1885-1906. Hileman, J.A., Allen, C.R. and Nordquist, J.M., 1973, Seismicity of the Southern California Region, January 1, 1932 to December 31, 1972; Seismological Laboratory, Cal-Tech, Pasadena, California. Kennedy, M.P. and Tan, S.S., 2007, Geologic Map of the Oceanside 30'x60' Quadrangle, California, California Geological Survey, Department of Conservation. Richter, C.F., 1958, Elementary Seismology, W.H. Freeman and Company, San Francisco, California. REFERENCES/Page 2 Rockwell, T.K., 2010, The Rose Canyon Fault Zone in San Diego, Proceedings of the Fifth International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics. Paper No. 7.06C. Rockwell, T.K., Dawson, T.E., Young Ben-Horin, J. and Seitz, G., 2014, A 21-Event, 4,000-Year History of Surface Ruptures in the Anza Seismic Gap, San Jacinto Fault, and Implications for Long-term Earthquake Production on a Major Plate Boundary Fault. Pure and Applied Geophysics, v. 172, 1143- 1165 (2015). Rockwell, T.K., Millman, D.E., McElwain, R.S. and Lamar, D.L., 1985, Study of Seismic Activity by Trenching Along the Glen Ivy North Fault, Elsinore Fault Zone, Southern California: Lamar-Merifield Technical Report 85-1, U.S.G.S. Contract 14-08-0001-21376, 19 p. Ross, Z.E., Hauksson E. and Ben-Zion Y., 2017, Abundant Off-fault Seismicity and Orthogonal Structures in the San Jacinto Fault Zone, Science Advances, 2017; 3(3): e1601946. Published 2017 Mar 15. Toppozada, T.R. and Parke, D.L., 1982, Areas Damaged by California Earthquakes, 1900-1949, California Division of Mines and Geology, Open-file Report. 82-17. U.S. Dept. of Agriculture, 1953, Aerial Photographs AXN-14M-19 and 20. 1SP VICINITY MAP Adams Street Homes 37 45 Adams Street Carlsbad, CA. CA CULTURAL ARTSCENTE Car1sbadHs Figure No. I Job No. 20-12852 20-12852-p.ai APN: ~ ~i -i !~ •_;;•;!.1h :c t i ' ( I I r 1~s~-,s ·1 ~) ~ ~= f r C I 1,;_, u p ~ I .f_'::...'i"...€~ "'·"'\!.'.' . I ""''"""" I -,;;;------; I I -·~1 ,-··v-,-=,-!,.•" I '.·'·.",~~,J,:.l ~ I tr., -•A·-.. r;t,,.f:\1' •~-i I { a,,_~ ~-===--- GEOLOGY LEGEND Artificial Fill ..,,,.,, <· <'. Qaf Qop 2-4 Old Paralic Deposits ( units 2-4) l P•RW<\ ! c, .\ I . LEGEND e INF-2 4 ' ·" -~!'.~ . ~· , . Approximate Location of Exploratory Trench Approximate Location of Infiltration Test 0 I:: .• I f • --~~: _·,,._.,,;:-, tu w IC 1-UJ DZDIIOrw,, ............ ..... 0 "' I I: Scale: 1 " = 30' (approximate) I PRELIMINARY SITE PLAN 3145ADAMS STREET CITY OFCARLSMO " PASCO LARET SUITER 1111111111111--• I ASSOCIATES lllnDll9> 1 __ , __ --121----- NOTE: 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 undated PRELIMINARY SITE PLAN by PASCO LARET SUITER & ASSOCIATES and from on-site field reconnaissance performed by GEi. PLOT PLAN Approximate Location of Proposed Biofiltration Basin Adams Street Homes 37 45 Adams Street Carlsbad, CA. Figure No. II Job No. 20-12852 Geotechnical Exploration, Inc. ( September 2020) 00 b <!) _J a. [,'.) 0 w <!) ~ <!) ,_ en en ::; c§ <( ~ "' ~ 8 _J z 0 ~ g a. X w r EQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED Rubber-tire Backhoe 2' X 1 0' X 5' Trench 8-3-20 SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH LOGGED BY ± 81' Mean Sea Level Not Encountered JKH FIELD DESCRIPTION AND ~ &= ~ &= ~ CLASSIFICATION ~ 0 g_ 0 g_ w w ~ WIY ~~ ::!: IY ::!:~ ...J w ::> j'.:: I 0 ...J DESCRIPTION AND REMARKS (/) ~~ ::> ::> ::5 en ::!: I-:a:-I-Cll Cl... c.5 -en -en Cl... ::!: ::!: (Grain size, Density, Moisture, Color) (/) c...-c...z I--~m w >-<( ,o 'w c...O 0 en en :::i ~::!: ~o O::!: ::!:O ~ SIL TY SAND , fine-to medium-grained, with SM -abundant roots. Loose to medium dense. Dry. ~ Brown. -~ ~ TOPSOIL - ~ 1 -~ ~ - ~ -~- -~ 1 3.4 105.5 ~ 2 -' ~ ---~ -► ~ -SILTY SAND, fine-to medium-grained, with SM -' -some roots. Medium dense to dense. Damp. -' Red-brown. I• 3 -8.1 128.5 -I• ► -I• OLD PARALIC DEPOSITS (Qop) -► I• -► -I• ' -I• -' 4-► 1,_ -I• -I• 2 - ---- -5 -~ - - -Bottom @5' - 6 - - - - Y. JOB NAME PERCHED WATER TABLE Adams Street Homes [2J BULK BAG SAMPLE SITE LOCATION [TI IN-PLACE SAMPLE 3745 Adams Street, Carlsbad, CA ■ JOB NUMBER REVIEWED BY LDR/JAC MODIFIED CALIFORNIA SAMPLE 0 NUCLEAR FIELD DENSITY TEST 20-12852 lr;-4,, Geo10<hnk" FIGURE NUMBER Exploration, Inc. '-~ STANDARD PENETRATION TEST Illa $ " ~ 0 ~ c:i i--: c:i 0 j'.:: q + _j b!:: wen en z 0 I-...JW -::!: en 3;:z 0...I en_ <( zo Cl... z o=> ::!:U ~c X 0 ...10 <CZ w u Cll U en= LOG No. T-1 ~ a3 ti (!) ...I a. r;\ 0 w /EQUIPMENT DIMENSION & 1YPE OF EXCAVATION Rubber-tire Backhoe 2' X 10' X 6' Trench SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH ± 81' Mean Sea Level Not Encountered ~ ~ :c l-a.. w C, -2 ---- -3- - - - ---4- -5--- -6-- - -- -7 - --- - -' w 0 -' a:, a.. ~ ! FIELD DESCRIPTION AND CLASSIFICATION DESCRIPTION AND REMARKS (Grain size, Density, Moisture, Color) SIL TY SAND , fine-to medium-grained, with roots and trash debris. Loose. Dry. Gray-brown. FILL (Qaf) SIL TY SAND , fine-to medium-grained, with abundant roots. Loose to medium dense. Dry. Brown. TOPSOIL SIL TY SAND , fine-to medium-grained, moderately cemented. Medium dense to dense. Damp. Red-brown. OLD PARALIC DEPOSITS (Qop) Bottom @6' u:i d u:i =i SM SM SM DATE LOGGED ' 8-3-20 LOGGED BY JKH ~ >-c-~ ~= C ~ 0::: 0 C, g_ ci ,..: ci w C, Q. w ' d WO::: ~~ ::a.o::: :a.~ ~A + _j b!:: wen ::, ~ en (.) ::, ::, ::, z 0 ~~ -'W ::i I-::Sen :a. I-:a.--:a. -en -en en_ <C en a.. :c a..~ a..z I--~m zo Cl.. z 0::, :a. (.) ,o •w a..O ~~ X 0 _,o '755 ~:a. ~c, o::a. :a. C, w (.) a:, (.) (!).__ _ _.__...__..__ ___________________ _,__..___...__ __ ....__..___ ....... _ _._ __ ....__....____. -, a. (!) ti; (/) :;; c3 <{ N "' "' ~ (!) g z 0 ~ g a. X w '- .Y [8J I]] ■ 0 ~ PERCHED WATER TABLE BULK BAG SAMPLE IN-PLACE SAMPLE MODIFIED CALIFORNIA SAMPLE NUCLEAR FIELD DENSITY TEST STANDARD PENETRATION TEST JOB NAME Adams Street Homes SITE LOCATION 3745 Adams Street, Carlsbad, CA JOB NUMBER REVIEWED BY LDR/JAC LOG No. 20-12852 4~:t--T-2 FIGURE NUMBER Exploration, Inc. lllb ffe ) 0 ~ a3 f--0 ('.) _j 0.. X w 0 w ('.) ('.) g z 0 ~ 0 ...J 0.. X w rEQUIPMENT DIMENSION & TYPE OF EXCAVATION Rubber-tire Backhoe 2' X 10' X 10' Trench SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH I f-c.. LU 0 2 4 6 8 10 ± 83' Mean Sea Level Not Encountered FIELD DESCRIPTION AND CLASSIFICATION -' wf--------------------~------i g ~ DESCRIPTION AND REMARKS u5 ~ } (Grain size, Density, Moisture, Color) <..:i u5 :::::i .Y ~ SIL TY SAND , fine-to medium-grained, with roots, concrete and brick debris. Loose to medium dense. Dry to damp. Red-brown. FILL (Qaf) SM SIL TY SAND , fine-to medium-grained, with SM roots, and brick debris. Loose to medium dense. Dry. Brown. FILL (Qaf) SIL TY SAND , fine-to medium-grained, with SM some roots. Loose to medium dense. Damp. Dark brown. TOPSOIL SIL TY SAND , fine-to medium-grained. Medium dense to dense. Damp. Red-brown. OLD PARALIC DEPOSITS (Qop) Bottom@ 10' JOB NAME SM PERCHED WATER TABLE Adams Street Homes BULK BAG SAMPLE SITE LOCATION DATE LOGGED 8-3-20 LOGGED BY JKH ft:= ~ >-= ~ Cl'.'.o 0 g_ LU 0 Cl. LU LU Cl'.'. ~~ :a: Cl'.'. :a:~ ::> ~ u ::> ::> ::> ::if-::i ci5 :a: f-:a:--en -en c.. S!? c..z f--~m ,o ' LU c..O ~:a: ~o o::a: ::a:o [I] IN-PLACE SAMPLE 3745 Adams Street, Carlsbad, CA ■ JOB NUMBER REVIEWED BY LDR/JAC MODIFIED CALIFORNIA SAMPLE 0 NUCLEAR FIELD DENSITY TEST 20-12852 •~jt-nkal FIGURE NUMBER Exploration, Inc. '-~ STANDARD PENETRATION TEST Ille ffe ,.., ~ ~ 0 ci i-: c:i d ~q + ~ _j en wen z 0 f--'LU -:a: en s:z c..:r: en_ <( zo c.. z o=> ::a:u ~c X 0 _.o cJ5e. LU u a:iu LOG No. T-3 ~ r EQUIPMENT DIMENSION & TYPE OF EXCAVATION Rubber-tire Backhoe 2' X 10' X 5' Trench SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH ± 83' Mean Sea Level Not Encountered ~ ~ I I-c... w 0 - 5 - - § 6 - ai ti (!) ...J a. ~ 0 LU -' w 0 -' (D c... :a: :a: >-<C en en FIELD DESCRIPTION AND CLASSIFICATION DESCRIPTION AND REMARKS (Grain size, Density, Moisture, Color) SIL TY SAND , fine-to medium-grained, with roots. Loose to medium dense. Dry. Brown. TRENCH BACKFILL (Qaf) --2 feet of topsoil was observed above the formation on both sides of the trench backfill. --4-inch diameter drain pipe. SIL TY SAND , fine-to medium-grained. Medium dense to dense. Damp. Red-brown. OLD PARALIC DEPOSITS (Qop) Bottom @5' u; <.) u; ::j SM SM DATE LOGGED 'I 8-3-20 LOGGED BY JKH ~ ~ 0 1';: u ~ i';:u-g ci ~ i--: w OE, w 0 0. ci ci WO::: ~j:'.: :a: 0::: :a:-j:'.:C! + _j I.!:: wen ::, j:'.: en (.)::, ::, ::, z 0 I--'W ::5 t;; ::s ci5 :a: I-:a:--:a: en s:z C... I -en -en en_ <C c...-c...z I--~z zo c... z o::> ::a:u ,o 'w c...O ~~ X 0 _,o <CZ ~:a: ~o o::a: :a:~ w (.) co(.) en= (!),___....__..._..__ ___________________ .....__..___..._ _ ___. __ ,__ _ __.__ ........ __ ...__...______, -, a. (!) lii VJ ::;; c§ < N "' ro N (!) g z 0 ~ 0 ...J a. X LU '" Y. ~ [I] ■ 0 ~ PERCHED WATER TABLE BULK BAG SAMPLE IN-PLACE SAMPLE MODIFIED CALIFORNIA SAMPLE NUCLEAR FIELD DENSITY TEST STANDARD PENETRATION TEST JOB NAME Adams Street Homes SITE LOCATION 3745 Adams Street, Carlsbad, CA JOB NUMBER REVIEWED BY LDR/JAC LOG No. 20-12852 4~,--T-4 FIGURE NUMBER Exploration, Inc. llld ~ ~ 0 ~ ;;; f-0 (!) ...J 0.. X w 0 w (!) (!) g z 0 ~ 0 ...J 0.. [.'.i rEQUIPMENT DIMENSION & TYPE OF EXCAVATION Rubber-tire Backhoe 2' X 10' X 5' Trench SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH ± 82' Mean Sea Level 5feet ~ ,!g_ -' :r: 0 t-a:, 0.. :::;; w in Cl 5-I• --- -- - 6- - - - y [Z1 w -' 0.. :::;; <( en FIELD DESCRIPTION AND CLASSIFICATION DESCRIPTION AND REMARKS (Grain size, Density, Moisture, Color) SIL TY SAND , fine-to medium-grained, with some roots and trash debris. Loose. Damp to moist. Yellow-brown. FILL (Qaf) --Fill depth ranges from 3'-4'. SIL TY SAND , fine-to medium-grained. Medium dense to dense. Moist to wet. Red-brown. OLD PARALIC DEPOSITS (Qop) y-seepage@ 5'. Bottom @5' JOB NAME (/) (.) (/) :;;; SM SM PERCHED WATER TABLE Adams Street Homes BULK BAG SAMPLE SITE LOCATION DATE LOGGED 8-3-20 LOGGED BY JKH ~ >-c 1)::c O::c., ~ Cl g_ w Cl a. w w a:: ~~ :::;; a:: :::;;- :::::,~ <..):::::, :::::, :::::, ::s ti; ::s u5 :::;; t-:::;;--en -en 0.. -c..z t--~m ,o 'w 0.. 0 ~:::;; ~Cl o:::;; :::,; Cl II] IN-PLACE SAMPLE 3745 Adams Street, Carlsbad, CA ■ JOB NUMBER REVIEWED BY LDR/JAC MODIFIED CALIFORNIA SAMPLE 0 NUCLEAR FIELD DENSITY TEST 20-12852 CG-4,--FIGURE NUMBER Exploration, Inc. ~ STANDARD PENETRATION TEST Ille ffe-'-. "I -:::s: ~ ci ,_; ci 0 ~q + _j !!:: en wen :z 0 t--'W -:::;; en ~z en_ <( 0.. :r: zo 0.. z o:::::> :::;;0 ~~ X 0 _,o <CZ w <..) a:, <..) en= LOG No. T-5 ~ 0 S! 00 1--0 C) __J n. >< w 0 w C) --, n. C) ti (/) ::. ~ <( ~ a, N C) g z 0 ~ 0 __J n. >< w rEQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED \. Rubber-tire Backhoe 2' X 1 O' X 4.5' Trench SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH ± 85' Mean Sea Level Not Encountered I l-a.. w Cl FIELD DESCRIPTION AND ~ CLASSIFICATION ~ g ~ t----DE_S_C_R-IP-TI-ON-AN_D_R_E_MA_R_K_S-----------~~-:---< ~ ~ ~ ~ (Grain size, Density, Moisture, Color) cr5 C. o (/) (/) ::i ~:;;; SIL TY SAND , fine-to medium-grained, with some trash debris. Loose. Dry. Gray-brown. FILL (Qaf) SM SIL TY SAND , fine-to medium-grained, SM -► moderately cemented. Dense. Damp. Red-brown. 2-► - OLD PARALIC DEPOSITS (Qop) - -1 8.6 121 .3 - 3 - - - - : V ~ --29% passing #200 sieve. 3.3 4 - - - - 5 -Bottom @4.5' - - - - 6 --- - - --- .Y JOB NAME PERCHED WATER TABLE Adams Street Homes ~ BULK BAG SAMPLE SITE LOCATION [I] IN-PLACE SAMPLE 3745 Adams Street, Carlsbad, CA ■ MODIFIED CALIFORNIA SAMPLE JOB NUMBER REVIEWED BY 8-3-20 LOGGED BY JKH w :;;;~ ::::, ::::, :;;; I--en I--a.. 0 o:;;; LDR/JAC 0 NUCLEAR FIELD DENSITY TEST 20-12852 cr~,•-m,., FIGURE NUMBER Exploration, Inc. l?'iJ STANDARD PENETRATION TEST lllf ~ LOG No. ,-.: ~ 1-:s: z o::> _,o coo T-6 "' ci 0 wen .JW 0..I :::;; (.) ~e, ~ 0 ~ al ci (!) ...J 0.. /;\ 0 w (!) -, 0.. (!) ti (/) ::;; i!i <( S'j ., "' (!) g z 0 ~ g 0.. >< w rEQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED Rubber-tire Backhoe 2' X 10' X4' Trench 8-3-20 SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH LOGGED BY ± 87' Mean Sea Level Not Encountered JKH FIELD DESCRIPTION AND 1i: = ~ 1i: = ~ 'a;' CLASSIFICATION LJ.J 0~ ::a;~ D g_ ~ LJ.J 0:: ~~ ::a;~ _J LJ.J :::,~ :I: 0 _J DESCRIPTION AND REMARKS u5 u:::, :::, :::, ::5 t; ::5 ci5 ::a; f--::a;-f--CD a.. {.) -en -Cf> a.. ::a; ::a; (Grain size, Density, Moisture, Color) u5 a..-a..z f---~z LJ.J >-<( ,o 'LJ.J a..O ::a;~ D en en :::i ~ ::E ~D 0 ::E -► SIL TY SAND , fine-to medium-grained, with SM -some roots. Loose to medium dense. Dry. Brown. --~ -► TOPSOIL - -► 1 -► - -- -► ---red-brown lense. - -► 1 -► 2-- --~ -► -SIL TY SAND , fine-to medium-grained, SM -► -moderately cemented. Dense. Damp. Red-brown. -► 3-• --► OLD PARALIC DEPOSITS (Qop) ---2 -► -- 4 - - - -Bottom@4' ---5-- ----- - 6 ----- -- - Y. JOB NAME PERCHED WATER TABLE Adams Street Homes ~ BULK BAG SAMPLE SITE LOCATION II] IN-PLACE SAMPLE 3745 Adams Street, Carlsbad, CA ■ JOB NUMBER MODIFIED CALIFORNIA SAMPLE REVIEWED BY LDR/JAC 0 NUCLEAR FIELD DENSITY TEST 20-12852 ,~,-FIGURE NUMBER Exploration, Inc. ~ STANDARD PENETRATION TEST lllg ffe, '- "' ~ ::R 0 c:i ci f-'. d~ ~tj + _j h!: en LJ.J en z 0 f--_J LJ.J -:::S, en :s:;z en_ <( a..:i::: zo a.. z o:::i :::e;u ~c X 0 _,o ~e. LJ.J u CDU LOG No. T-7 ~ 0 S! iii >-0 CJ _j a. >< w 0 w CJ CJ g z 0 ~ g a. >< w r EQUIPMENT DIMENSION & TYPE OF EXCAVATION Rubber-tire Backhoe 2' X 10' X 8' Trench SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH ± 91' Mean Sea Level Not Encountered 2 3 4 5 6 7 8 9 FIELD DESCRIPTION AND CLASSIFICATION ~ wf--------------------~-; fil 1[ DESCRIPTION AND REMARKS cri ~ ~ (Grain size, Density, Moisture, Color) SILTY SAND, fine-to medium-grained, with some roots. Medium dense. Dry to damp. Gray-brown. FILL {Qaf) SILTY SAND, fine-to medium-grained, with some roots. Medium dense to dense. Damp. Light gray-brown. FILL {Qaf) SIL TY SAND , fine-to medium-grained. Medium dense to dense. Damp. Red-brown. OLD PARALIC DEPOSITS {Qop) Bottom @8' JOB NAME cj cri :::i SM SM SM y_ PERCHED WATER TABLE Adams Street Homes ~ BULK BAG SAMPLE SITE LOCATION DATE LOGGED 8-3-20 LOGGED BY JKH ~ >-c-gz-&= ll'.'.o ~ 0 g_ w 0-3, w WO'.'. ~~ ::a:ll'.'. ::;;- ::::, ~ (.)::::, ::::, ::::, ::if-::i u5 :a: f-:a:--en -en a...~ a...z f--~d:l ,o 'w a...O ~:a: ~o o::a: ::a:o 5.4 110.7 [TI IN-PLACE SAMPLE 3745 Adams Street, Carlsbad, CA ■ JOB NUMBER REVIEWED BY LDR/JAC MODIFIED CALIFORNIA SAMPLE 0 20-12852 4!;Cjl Geote<hnkaJ NUCLEAR FIELD DENSITY TEST FIGURE NUMBER Exploration, Inc. \. ~ STANDARD PENETRATION TEST lllh ffe 'I ;g-~ ci .....: ci ci ~q + _j b!:: wen en z 0 f-~w -:a: en :s: z a...:r: en_ <a: zo a... z o=> ::a:o ~~ X 0 ~o "3e. w (.) co (.) LOG No. T-8 ~ /"EQUIPMENT DIMENSION & lYPE OF EXCAVATION DATE LOGGED "I Rubber-tire Backhoe 2' X 10' X 8' Trench 8-3-20 SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH LOGGED BY ± 91' Mean Sea Level Not Encountered JKH FIELD DESCRIPTION ~ AND 1;:'§' i;: 'o !!., ~ C ci CLASSIFICATION UJ o.e, UJ 0 Cl. ci ~ d~ UJ IX'. ~~ ::;; IX'. ::.~ ~q + _j _, UJ ti) ~~ :::, :::, :::,~ UJ Cl) 0 _, DESCRIPTION AND REMARKS ::i ci5 ::;; I-::;;--::. z g s:!z _JUJ Ill a. <.) a.~ -Cl) -Cl) Cl)-<( z a. ::c ::;; ::;; (Grain size, Density, Moisture, Color) ~ a.z I--~ a5 zo a. 0 o:::> ::;; (.) >-<( ,o ' UJ Q.. 0 ~c 1;:i (.) _,o <CZ Cl) Cl) :::, ~::;; ~o o::. ::.o Ill (.) Cl)= SIL TY SAND , fine-to medium-grained, with SM some roots. Medium dense. Dry. Gray-brown. 1 FILL(Qaf) SIL TY SAND , fine-to medium-grained, with SM 2 abundant roots. Medium dense. Damp. Red-brown. FILL (Qaf) 3 4 --23% passing #200 sieve. 8.6 7.6 130.4 5 --becomes loose to medium dense and dark brown. 5.4 108.0 6 7 SIL TY SAND , fine-to medium-grained, SM moderately cemented. Dense. Damp. Red-brown. 8 OLD PARALIC DEPOSITS (Qop) § O> Bottom@8' g 9 ~ Sl (!).___....__ ....... ___________________ ...____. _ __. __ ....__ ....... __ ..__ ....... __ ...__...___, § ti; U) I "' :ll ~ (!) g z 0 ~ ~ w \.. y ~ [I] ■ 0 ~ PERCHED WATER TABLE BULK BAG SAMPLE IN-PLACE SAMPLE MODIFIED CALIFORNIA SAMPLE NUCLEAR FIELD DENSITY TEST STANDARD PENETRATION TEST JOB NAME Adams Street Homes SITE LOCATION 3745 Adams Street, Carlsbad, CA JOB NUMBER REVIEWED BY LDR/JAC LOG No. 20-12852 u;;i-T-9 FIGURE NUMBER EXploratlon, Inc. llli ~ .) 0 ~ 00 ti (!) 1S a, w u.. iii (!) 135 130 125 120 115 110 ~ ci5 as 105 Cl ~ Cl 100 95 90 85 80 75 0 \ \ J .... V I 1, 5 \ 1 ' \ \ 1 \ \ \ ' \ I\ \ ' \ \ \ . I\ ' ' \ \ 1 \ \ I\ \ ' \ \ ~ ' ' I\ 1 I I\ ' ' I\ \ \ \ ' I\ I\ I\ \ \ ~ \ \ I\ \ 10 15 Source of Material T-1 @2.0' Description of Material SIL TY SAND (SM}, Red-brown Test Method ASTM 01557 Method A \ \ TEST RESULTS \ 1 ~ Maximum Dry Density 128.5 PCF I\ \ ~ Optimum Water Content 8.1 % \ \ I\ \ ' \ \ Expansion Index (El) I\ \ \ I\ I\ I\ \ II ' I\ ' \ \ '\ I\ \ ' \ I\ I\. I\ \ I\ Curves of 100% Saturation I\ ' for Specific Gravity Equal to: \ I\ I\. I\ \ I\ 2.80 I\ \ \ I\ I\.. 2.70 I\ \ I\. I\ I'\. ' 2.60 \ I'--.. \ I'\ I\ I\. I'\ \ II. I\ I'\. ~ I\ " \ I'. I'\. '\ I\.. r'\ ' I\.. I'\ '\ 1'. I'\ '\ '"- I'\ '\ ... 1'. r---l"I ... ,.._ f's-"' '1'. I"-"' "- I'-. " I 11"1 'I 11'\I 20 25 30 35 40 45 0 a:: ~r------==----==-------------W...:...A.:..:.T.::.ER~C.:..O:..:.NT.:...::E:::..N:..:.T.:..., •:.:.¼ _______________ -I ~ 4ri-4~I Geotechnical MOISTURE-DENSITY RELATIONSHIP z Exploration, Inc. Figure Number: IVa g Job Name: Adams Street Homes ~ Site Location: 3745 Adams Street, Carlsbad, CA :. 8 ____________________ ..i..;J.;.o.;;,b.;.N;,;;u;,;,;m~b;,;;e;.;.r;..: .;;;2.;;,0·..;1~2;,;;;8.;;,52;;;_ __________ ...J o3 ti (.') ~ w LJ.. w (.') 135 130 125 120 115 110 't3 Cl. ~ ci5 m 105 0 >-0::: 0 100 95 90 85 80 75 0 .a J I 4 5 I\ \ \ \ \ \ 1 \ \ ' \ \ \ \ \ \,\ \ \ \ \ \I\ \ l \ \ \ I\ \ L\ ' \ -I\ ' I\ \ II. \ \ \ I\ \ \ I\ I\ \ \ I\ \ 10 15 Source of Material T-9@4.0' Description of Material SIL TY SAND (SM}, Red-brown Test Method ASTM 01557 Method A \ \ \ 1 I\ \ TEST RESULTS I\ \ ' \ \ Maximum Dry Density 130.4 PCF rl \ ' Optimum Water Content 7.6 % \ I\ I\ \ ' \ \ Expansion Index (El) rl \ ~ \ I\ I\ T\ \ I\ I\ \ \ I\ I\ \ ' \ I\ I\ \ l\ Curves of 100% Saturation \ I\ ' for Specific Gravity Equal to: \ I\ I\. I\ \ II. 2.80 I\ \ \ '\ I\. 2.70 I\ \ rl,. '\ \ ' 2.60 \ '\ \ I\ I\. I'\ \ II. I'\ \ ' ' I\ f' \ I\. I" I\ " I\. I"-' I\. I'\ ' 1\ I"'\ '\ ' I'\ '\ ........ I'\-I"--... ,..,. r--. "' 1'. I'\ " '- I'\ " I"-" "-- 20 25 30 35 40 45 Pacific Base Map Onshore basa (hyps.091aph)I. hydrography, and ttao&pOrtaliOn) from U.S.G.S. digital line graph (DLG) dala, Sao Olesp 30' x 60' meltic quad<angla. Shadlld topographic base from u S.G.S. digital tleva9on modefs (DEM'11). Offshore b81h)'IT!6trie contours and shaded bmhymotry from N.O.A A. single and multibearn date Projection is UTM, zone 11. North American Datum 1927. ilUSGS ~ ..... _,.._,,,... u This map was funde<I in part by the U.S. GeolOgocal Survey Nation&! Cooperative Geologic Mapping Progrem STATEMAP Award r.0. 98HOAG2049, Prep<1rad in cooperahoo with the U.S. Geological Su1Vay, Soo\hern Clllifcrnia Ara al Mapping Project. CopyrigM o 2008 b)' the California Oepl,lrtment or Conserva1lon. All rig his reserved. No part of lhis publication may be reproduced \ltithoUt written consent of the CatifoMia Geaogical Survey. The Oapartmenl of Conservation makes no warranties II~ to \tie suitability or 111ill product for any panicular purpose. Adams-OC-geo.ai Adams Street Homes 3745 Adams Street Carlsbad, CA. EXCERPT FROM GEOLOGIC MAP OF THE OCEANSIDE 30' x 60' QUADRANGLE, CALIFORNIA Compiled by 70 ....1...-%--- ---... . <QQ1s1, ii ~ 70 -+ Gl ~ -+- ..1,'_ -a- 2 .... Michael P. Kennedy1 and Siang S. Tan1 2007 Digital preparation by Kelly R. Bovard2, Rachel M. Alvarez2, Michael J. Watson2, and Carlos I. Gutierrez' l. Oepirtmentd~Uon.Catromi&Gedoglcal~ 2. U.S Gedogical SUMy, Oepamient cl Eatt, Sciences, UnM,teity cf Califllmia, Ri'oerslde ... ' s APPROXIW.TE ME.Ml OECLIIIA.TIOl,2007 ONSHORE MAP SYMBOLS DESCRIPTION OF MAP UNITS ConUlct-Contact between geologic units; dotted where concealed. Fault-Solid where accurately located; da8l1ed where approximately located; dotted whore cmculod. U = uplhrown block, D = downthr<1WD block. Am,,, and munber indica!e diredion and IJl8le of dip of bult plane. Anttdlne-SoJid where acwrately located; dotted where conttlled. Syncline-Solid where IOOlllltely located; dotted where cooeealed Kgd----gnnite p,gmatite dike Oosed depresiion--Clcsed depression in Elsinore fault zone. Landslide-Arrows indicate frincipal direction of movement. Queried where existence ii questionable. Strike and dip ol beds Inclined Overturned Vertical Horlmntal Strike and dip of Igneous foliation Inclined Vertical Strike and dip ol li:oeou, Joints Inclined Vertical Strike and dip of metamorphic foliation Inclined Strike and dip of sedimentary joints Vertical Old paralic deposits, I Qop2-4 I Units2-4 Santiago Formation Figure No. V Job No. 20-12852 11&==,~ ~"' August 2020 SCHEMATIC RETAINING WALL SUBDRAIN RECOMMENDATIONS Retaining Woll Proposed Grode Proposed Grode I I I 18'1 ~J-Drain 200/220 Properly Waterproofing Compacted To Top Of Woll Backfill ✓-Drain SWD Sealant NOTTO SCALE NOTE: As on option to Mirodroin 6000, Grovel or Crushed rock 3/4" maximum diameter may be used with o minimum 12" thickness along the interior face of the wall and 2.0 cu.ft./ft. of pipe grovel envelope. 20-12852-V Figure No. VI Job No. 20-12852 ,~. ,,_,,,,,..., ~I,-, -.,,1on,flon, Inc. ~ ~ September 2020 AP PENDIX A APPENDIX A UNIFIED SOIL CLASSIFICATION CHART SOIL DESCRIPTION Coarse-grained (More than half of material is larger than a No. 200 sieve) GRAVELS, CLEAN GRAVELS (More than half of coarse fraction is larger than No. 4 sieve size, but smaller than 3") GRAVELS WITH FINES (Appreciable amount) SANDS, CLEAN SANDS (More than half of coarse fraction is smaller than a No. 4 sieve) SANDS WITH FINES (Appreciable amount) GW GP GC SW SP SM Well-graded gravels, gravel and sand mixtures, little or no fines. Poorly graded gravels, gravel and sand mixtures, little or no fines. Clay gravels, poorly graded gravel-sand-silt mixtures Well-graded sand, gravelly sands, little or no fines Poorly graded sands, gravelly sands, little or no fines. Silty sands, poorly graded sand and silty mixtures. SC Clayey sands, poorly graded sand and clay mixtures. Fine-grained (More than half of material is smaller than a No. 200 sieve) SILTS AND CLAYS Liquid Limit Less than 50 Liquid Limit Greater than 50 HIGHLY ORGANIC SOILS ML Inorganic silts and very fine sands, rock flour, sandy silt and clayey-silt sand mixtures with a slight plasticity CL Inorganic clays of low to medium plasticity, gravelly clays, silty clays, clean clays. OL Organic silts and organic silty clays of low plasticity. MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts. CH Inorganic clays of high plasticity, fat clays. OH Organic clays of medium to high plasticity. PT Peat and other highly organic soils APPENDIX B 9/4/2020 U.S. Seismic Design Maps OSHPD ~~bI Jo.b N2. 20·-1235-z_ 3745 Adams St. Carlsbad, California Latitude, Longitude: 33.1550, -117.3357 Chase Field Magnolia /we gle Date Days Inn by ~ Wyndham Carlsbad T Design Code Ret.renca Document Risk Category SlteClass · ' St Patrick ft Catholic Church V 9/4/2020, 11:19:42AM ASCE7-16 II 0-Default (See Section 11.4.3) Type Ss s, SMS 8M1 Sos S01 Value 1.059 Description 0.384 1.271 null-See Section 11.4.8 l), 7 3 7 0.847 null -5ee Section 11.4.8 l'ype Value O..Crlptlon MCER ground motion. (for 0.2 second period) MC~ ground motion. (tor 1.0S period) Site-modifled spectral acceleration value Site-modified spectral acceleration value Numeric seismic design value at 0.2 second SA Numeric seismic design value et 1.0 second SA SOC null -See Section 11.4.8 'J) Seismic design category Fa 1.2 Site amplification factor at 0.2 second F, null-See Section 11.4.8 \, q Zs11e emptificatlontactor at 1.0 second PGA 0.466 MCfc. peal( ground acceleration FPGA ·1.2 Site amplification factor at PGA PGAu 0.56 Site modified peal( ground acceleration TL 8 Long-period transition period in seconds SsRT 1.059 Probablllstic risk-targeted ground motion. (0.2 second) SsUH 1.183 Factored uniform-hazard (2% probability of exceedance in 50 years) spectral acceleratiQn SsD 1.5 Factored deterministic acceleration valtJe. (0.2 second) S1 RT 0.384 Probabilistic risk-targeted ground motion. (1.0 second) S1UH 0.423 Factored uniform-hazard (2% probebHl!y of exceedance in 50 years) spectral acceleration. s10 o.s Factored deterministic acceleration value. {1.0 second} PGAd 0.554 Factored deterministic acceleration value. (Peak Ground Acceleration) CRS 0.895 Mapped value of the risk coefficient at short periods ~1 0.906 Mapped value of the risk coefficient at a period of 1 s https:f/seismicmaps.org Map data ©2020 1/2