appendix f geotechnical report - los angelescityplanning.lacity.org/eir/yuccaproject/deir/deir...

City of Los Angeles April 2007

Yucca Street Condos Administrative Draft Environmental Impact Report

APPENDIX F

GEOTECHNICAL REPORT

PRELIMINARY GEOTECHNICAL REPORT PROPOSED HIGH RISE RESIDENTIAL DEVELOPMENT

6230 YUCCA STREET HOLLYWOOD, CALIFORNIA

Prepared for

6230, LLC 13327 Beach Avenue

Marina Del Rey, CA 90292

Prepared by

GROUP DELTA CONSULTANTS, INC. 2291 West 205th Street, Suite 105

Torrance, CA 90501

Project No. L-718 November 17, 2006

November 17, 2006 6230, LLC 13327 Beach Avenue Marina Del Rey, CA 90292 Attention: Mr. David Jordon GDC No. L-718 Subject: Preliminary Geotechnical Report Proposed High Rise Residential Development 6230 Yucca Street

Hollywood, California Dear Mr. Jordon: Group Delta Consultants (GDC) is pleased to submit our Preliminary Geotechnical Report for the proposed high-rise residential development planned at 6230 Yucca Street in Hollywood. We appreciate the opportunity to provide geotechnical services for this project. If you have any questions pertaining to our report, or if we can be of further service, please do not hesitate to contact us. Respectfully submitted, GROUP DELTA CONSULTANTS, INC.

Thomas D. Swantko, GE #813 Steven H. Kolthoff, C.E.G. #1965 Principal Geotechnical Engineer Senior Geologist, Exp. 8/31/07 Distribution: (6) Addressee N:\Projects\700-799\L-718 6230 Yucca\Documents\L-720 6230 Yucca Street Report.doc

TABLE OF CONTENTS

Section Page No. 1.0 INTRODUCTION 1

1.1 Project Description 1 1.2 Purpose and Scope of Work 1

2.0 FIELD EXPLORATION AND LABORATORY TESTING 2 2.1 Field Exploration 2 2.2 Laboratory Testing Program 2

3.0 GEOLOGY AND SEISMIC SETTING 3 3.1 Regional And Local Geology 3 3.2 Seismic Setting 3

4.0 SITE CONDITIONS 3 4.1 Surface Conditions 3 4.2 Subsurface Conditions 4 4.4 Ground Water 4

5.0 DISCUSSION AND RECOMMENDATIONS 5 5.1 General 5 5.2 Demolition 5 5.3 Removals 6 5.4 Earthwork 6 5.5 Temporary Excavations 7

5.5.1 General 7 5.5.2 Dewatering 8 5.5.3 Shoring 8 5.5.4 Monitoring Of Shoring 9

5.6 Foundation Support 9 5.6.1 Alternate Foundation Types 9 5.6.2 Lateral Resistance 10 5.6.3 Settlement 10 5.6.4 Basement Slab 10 5.6.5 Design For Hydrostatic Pressures 11

5.7 Basement Walls 11 5.7.1 Static Pressures 11 5.7.2 Seismic Pressures 11 5.7.3 Backfilling 12 5.7.4 Waterproofing and Drainage 12

5.8 Site Drainage And Infiltration 13 5.9 Soil Expansive Potential 13 5.10 Soil Corrosivity 13 5.11 Environmental Issues 14

Preliminary Geotechnical Report November 17, 2006 Proposed High Rise Residential Development Page ii 6230 Yucca Street, Hollywood, CA GDC Project No. L-718

6.0 GEOLOGICAL HAZARD EVALUATION AND SEISMIC DESIGN COEFFICIENTS 14

6.1 Ground Surface Rupture 14 6.2 Ground Motion 14

6.2.1 Probabilistic Seismic Hazard Analysis 15 6.2.2 Seismic Ground Motions 15

6.3 Seismic Coefficients 16 6.4 Secondary Seismic Effects 16

6.4.1 Liquefaction and Seismic Settlement 16 6.4.2 Slope Instability 17 6.4.3 Tsunami and Seiches Potential 17 6.4.4 Ground Lurching 18 6.4.5 Flood Hazard 18 6.4.6 Oil Field Gas Potentials 18 6.4.7 Other Geologic Hazards Or Considerations 18

7.0 POST INVESTIGATION GEOTECHNICAL SERVICES 18

8.0 LIMITATIONS 19

9.0 REFERENCES 20 LIST OF FIGURES Figure 1 Vicinity Map Figure 2 Boring Location Plan Figure 3 Generalized Geologic Cross-Section A – A’ LIST OF APPENDICES Appendix A Field Exploration Appendix B Laboratory Testing Appendix C Seismic Data Appendix D Liquefaction Analysis

PRELIMINARY GEOTECHNICAL REPORT PROPOSED HIGH RISE RESIDENTIAL DEVELOPMENT

6230 YUCCA STREET HOLLYWOOD, CALIFORNIA

1.0 INTRODUCTION This report provides the results of our preliminary geotechnical investigation performed for the proposed high-rise residential development planned at 6230 Yucca Street in Hollywood, California. The location of the proposed development is shown in Figure 1. We previously performed a feasibility level geotechnical investigation report for the project dated July 20, 2006. The full title of this report is provided in the Reference Section. 1.1 Project Description Our understanding of the project is based on discussions with 6230, LLC. A site plan is provided in Figure 2. The site is located at the southwest corner of Yucca Street and Argyle Street in Hollywood. The site is about 150 feet by 170 feet in plan, and currently contains a single-story commercial building and asphalt paved parking area. The existing improvements will be demolished to accommodate the planned development. The conceptual project involves the construction of a 15-story high-rise residential tower, with 2 to 3 levels of subterranean parking. Structural loads are not available at this time. 1.2 Purpose and Scope of Work The purpose of this report is to provide geotechnical and foundation recommendations for the proposed development. Our authorized scope of work included: • Performing a site visit to assess the existing conditions and select boring

locations. • Review of available published geologic maps, geotechnical data and reports. • Drilling and sampling 2 hollow-stem auger borings to a depth of about 60 feet. • Performing laboratory testing to characterize the subsurface profile and evaluate

the physical properties and engineering characteristics of the soils encountered.

Preliminary Geotechnical Report November 17, 2006 Proposed High Rise Residential Development Page 2 6230 Yucca Street, Hollywood, CA GDC Project No. L-718

• Performing engineering analyses of the field and laboratory data to develop preliminary geotechnical recommendations for the planned construction, including recommendations for demolition, removals, site grading, excavations, placement of compacted fill and backfill, foundations, lateral resistance, settlement, and pavement design.

• Preparation of this report. 2.0 FIELD EXPLORATION AND LABORATORY TESTING 2.1 Field Exploration The subsurface conditions at the site were investigated by drilling 2 hollow-stem auger borings at the locations shown in Figure 2. Both of the borings were located in the parking lot south of the building. The rest of the site contains an existing building and is inaccessible to drilling equipment. The borings were advanced to a depth about 60 feet below the existing grades. Both relatively undisturbed samples and Standard Penetration Tests (SPT) samples were taken in the borings. The explorations were performed under the continuous technical supervision of our field engineer, who also maintained detailed logs of the soils encountered, classified the materials, and assisted in obtaining samples for evaluation and testing. Complete details of the field exploration program, including copies of the boring logs, are presented in Appendix A. 2.2 Laboratory Testing Program The soil samples obtained from the borings were taken to our laboratory for further visual examination and laboratory testing. Laboratory tests were performed to assist in classifying and correlating samples, and for evaluating their physical properties and engineering characteristics. The laboratory testing is supplemented by the results of the SPT sampling conducted in the borings, which provide additional means to evaluate in situ soil properties, such as relative density, shear strength and compressibility. Details of the laboratory testing program, including test results, are provided in Appendix B.


3.0 GEOLOGY AND SEISMIC SETTING 3.1 Regional And Local Geology The site is located in the northwestern area of the Central Block of the Los Angeles Basin, bordered on the north by the Santa Monica Mountains, on the northeast by the Elysian Hills, on the south by the Baldwin Hills and Central Plain, and on the west by Beverly Hills. The revised Quaternary geologic map of the Hollywood Quadrangle (CDMG, 1998) shows that the site is underlain by native Quaternary alluvial soils, consisting of young Holocene fan deposits over older Pleistocene fan and terrace deposits. The Holocene deposits are primarily comprised of interbedded layers of sand, silt and clay, which generally tend to be loose to medium dense. These younger alluvial deposits are estimated to generally be about 10 to 15 feet thick in the area, but vary in thickness and could extend deeper. Below the young alluvial sediments are deposits of Pleistocene older fan and terrace deposits, which consist primarily of denser layers of clay and silt. 3.2 Seismic Setting The site is located in seismically active southern California and there is the potential for the site to experience strong ground shaking from local and regional earthquakes during the life of the project. The closest active fault is the Hollywood fault, which is located about 0.3 miles north of the site and is capable of generating a magnitude (MW) 6.4 earthquake. The ramps of the upper Elysian Park and Puente Hills Blind Thrust Faults are located below the site a depth of 1.8 and 3.5 miles, respectively. The Newport-Inglewood Fault Zone and Santa Monica fault are located at a distance of 5.5 and 5.7 miles from the site and are considered capable of generating magnitude (MW) 7.1 and 6.6 earthquakes, respectively. 4.0 SITE CONDITIONS 4.1 Surface Conditions The site contains an existing single-story commercial building, about 18,600 square feet in plan, with an asphalt paved parking area located south of the building. The existing site grade is about El. + 400 feet. The surface of the parking lot is fairly flat and appears to drain to the east. A chain link fence is around the parking lot. There is a retaining wall at the west end of the parking lot, where the parking lot is about 4


feet higher that the adjacent property. 4.2 Subsurface Conditions Both of our borings encountered generally similar soil conditions. The existing AC pavement is generally 2 inch thick with 2 inches of aggregate base. Boring B-1 encountered possible fill that may be up to 6 feet deep. The fill consisted of generally loose to medium dense silty sand, with scattered gravel. It should also be anticipated that old fill could be present anywhere on the site and could be locally deeper. Any existing fill should be considered to be uncertified, but should be removed during excavation planned for the basements. There is also the potential for the remnants of previous construction to be encountered anywhere on the site, including foundations, slabs, basements, pits, buried tanks, cesspools and utilities. Below any fill, the borings encountered native alluvial soils consisting of interbedded layers of sand, silt and clay. The sandy layers were generally medium dense to dense, and had a SPT N-value typically ranging from 17 to 30. Below a depth of about 45 feet the N-values ranged from 31 to 50+. The clayey layers were very stiff, with SPT N-values of 17 to 32 and a measured shear strength of 3,000 to 3,500 psf. 4.4 Ground Water Borings B-1 and B-2 encountered ground water at depths of 24 and 44 feet, respectively, at the time of drilling. No published boring logs or well logs in the site area were available for review. Based on the California Division of Mines and Geology (CDMG) Open-File Report 98-026, the historic highest groundwater in the site area is reported at a depth of more than 80 feet. It is believed the ground water found in the borings is a perched condition, where the water is perched on top of clay layers. The site is located along the toe of hills present to the north and is underlain with interbedded alluvial soils. With such a geologic environment, it is not usual for perched ground water levels to vary significantly over relatively short horizontal distances.


5.0 DISCUSSION AND RECOMMENDATIONS 5.1 General Based on the findings of our field exploration, laboratory testing, and engineering analysis, it is our opinion that the site is suitable from a geotechnical standpoint for the proposed construction. Depending on final loads, it is our opinion that either a structural mat or driven piles bearing in the dense sands below a depth of about 45 feet can be used to for support. The use of conventional spread footings may also be possible, pending the results of the design level geotechnical investigation. The design level investigation should include additional borings and Cone Penetrations Test (CPT) probes. Existing uncertified fill was found in the borings to a depth of up to about 5 to 6 feet, but will be removed during the planned excavation for the basements. Since perched water was found as high as 24 feet, plans should be made to control ground water during and after construction. Preliminary geotechnical recommendations for the project are provided below. 5.2 Demolition Prior to the start of earthwork, the existing improvements on the site will require demolition and removal, including the one-story building, foundations, slabs, pavements, walls and utilities. We understand there is also an underground diesel storage tank(s) on the site. It is not known if the existing building contains a basement, below ground pits, or if there are other buried tanks or structures. It should be anticipated that the buried remnants of previous construction could also be encountered anywhere on the site, including foundations, walls, slabs, basements, cesspools, tanks and utilities. Any void created from the demolition should be properly backfilled to the limits determined by the project geotechnical engineer. Any soils loosened or disturbed during the demolition should also be removed. The civil engineer should identify the presence and location of all existing utilities on the property. Precautions should be taken to remove, relocate or protect existing utilities, as appropriate.


5.3 Removals Up to 6 feet of fill was encountered in the borings. It should be anticipated that old fill could also exist anywhere on the site and could be locally deeper. Any old fill should be considered to be uncertified and should not be used for support of structures and pavements. Since 2 to 3 levels of basement are planned, any existing fill will be removed during excavation of the site. 5.4 Earthwork All grading should conform to the requirements of the City of Los Angeles Grading Division and the general grading recommendations outlined below. 1. The grading contractor is responsible for notifying the project geotechnical

engineer of a pre-grading meeting prior to the start of grading operations and anytime the operations are resumed after an interruption.

2. Prior to the start of earthwork the existing improvements will require demolition,

as discussed in Section 5.2. Existing utilities should be removed, relocated or protected, as appropriate.

3. As discussed in Section 5.3, any existing fill is uncertified, but will be removed

during the planned basement excavation. 4. The sides of the basement excavation will require shoring with one to two rows

of tie-back anchors, as discussed in Section 5.5. 5. The bottom of the completed excavation should be observed by the project

geotechnical engineer, while it is proofrolled with loaded equipment. Any loose or yielding soils should be overexcavated and recompacted to the limits determined by the project geotechnical engineer.

6. The bottom of the excavation should then be scarified to a depth of 6 inches,

moisture conditioned to between 0 to 2 percent wet of the optimum moisture content, and compacted to at least 95 percent relative compaction as determined by ASTM Test D1557.

7. Any fill placed under structures or pavement and any backfill placed adjacent to

buried walls is defined as “structural fill.” All structural fill should consist of predominantly sandy soils and should be free of expansive clay, rock greater than 3 inches in maximum size, debris and other deleterious materials. All


structural fill should be compacted to at least 95 percent of the maximum dry density determined by ASTM D1557. Fill placed in non-structural and landscape areas should be compacted to at least 90 percent.

8. In general, the sandy layers encountered in our borings may be used as

structural fill. However, the clayey and silty soils encountered in our explorations will not be acceptable for reuse as fill or backfill. All fill soils shall be approved by the project geotechnical engineer.

9. All earthwork and grading should be performed under the observation of the

project geotechnical engineer. Compaction testing of the fill soils shall be performed at the discretion of the project geotechnical engineer. Testing should be performed for approximately every 2 feet in fill thickness or 500 cubic yards of fill placed, whichever occurs first. If specified compaction is not achieved, additional compactive effort, moisture conditioning, and/or removal and recompaction of the fill soils will be required.

10. All materials used for asphalt concrete and base shall conform to the 2006

“Green Book” or the equivalent, and shall be compacted to at least 95 percent relative compaction.

11. If, in the opinion of the geotechnical engineer, contractor, or owner, an unsafe

condition is created or encountered during grading, all work in the area shall be stopped until measures can be taken to mitigate the unsafe condition. An unsafe condition shall be considered any condition that creates a danger to workers, on-site structures, on-site construction, or any off-site properties or persons.

5.5 Temporary Excavations 5.5.1 General We understand that up to three levels of below grade parking are planned, which will require an excavation up to about 30-feet deep. The excavation will be made in generally loose to firm alluvial soils consisting of interbedded layers of sand, silt and clay. The excavation should be readily accomplished using conventional heavy construction equipment. During excavation, shoring will be required to protect adjacent property and city streets. All excavation slopes should meet the minimum requirements of the Occupational Safety and Health Association (OSHA) Standards. Maintaining safe and stable slopes on excavations is the responsibility of the contractor and will depend on the


nature of the soils and groundwater conditions encountered and his method of excavation. Excavations during construction should be carried out in such a manner that failure or ground movement will not occur. The contractor should perform any additional studies deemed necessary to supplement the information contained in this report for the purpose of planning and executing his excavation plan. 5.5.2 Dewatering The ground water table was found at a depth of 24 feet in Boring B-1 and 44 feet in B-2. It is believed the ground water found in the borings is a perched condition, where the water is perched on top of clay layers. It is expected that the perched water level may vary throughout the site, even over short horizontal distances. During construction, it is anticipated that ground water can be controlled using shallow trenches, sumps and pumps. However, to provide further definition of the ground water conditions at the site, one or more monitoring wells are recommended to be installed during the design-level geotechnical investigation. If it is necessary to dispose of water during construction, a discharge permit will be required from the Regional Water Quality review Board. This will require testing of the ground water for contaminants, and should be planned for in the project schedule. 5.5.3 Shoring Because of the depth of the excavation, a soldier pile and tied-back shoring system will be required to protect adjacent property and streets. The design of the shoring system will be the responsibility of the shoring designer. Since the tied-back anchors will extend offsite, approval will be required from the City the adjacent property owners. This should be planned for in the project schedule. The soldier piles may consist of steel H-beams placed inside a drilled and cast-in-place concrete pile. Structural concrete should be used below the bottom of excavation and lean concrete above, so the concrete can be chipped out to place the lagging. Piles should be 2 feet in diameter and installed on about 6-foot centers. Lagging will be required to support and maintain full contact with the retained soils. Anchored or braced shoring should be designed for a uniform lateral earth pressure equal to 25H psf, where H is the height of the excavation. Surcharge loads from equipment or stockpiled material should be kept behind the top of the shoring a horizontal distance of at least twice the depth of the excavation, or the shoring


should be designed for the additional pressure. Traffic loads from adjacent areas should also be added to the lateral earth pressures. The passive pressure available in the native soils/bedrock below the bottom of the excavation may be taken as an equivalent fluid pressure of 300 pcf. To account for the rounded shape of the soldier piles, when calculating the passive pressure on individual piles spaced at 6 feet center to center, the equivalent fluid pressure may be multiplied by a factor of 2. During installation, each anchor will require load testing and pre-loading per City of Los Angeles requirements. It is anticipated that the upper anchors and possibly some shoring will also need to be removed from below city streets, after permanent walls and floors are complete. It may be possible to detention but leave the anchors in-place under private property, provided this is approved by the property owners. 5.5.4 Monitoring Of Shoring A survey-monitoring program should be implemented to monitor shoring displacements during construction. In addition, nearby improvements should also be surveyed and photographs and/or video taken to document baseline conditions. The deflection at the top of the shoring should be limited 1 inch. If the shoring exceeds 1-inch or if distress or settlement is noted adjacent to the top of shoring, an evaluation should be performed and corrective measures taken. 5.6 Foundation Support 5.6.1 Alternate Foundation Types Due to the relatively high column loads expected, either driven piles or a structural mat are anticipated to be required in order to control settlements. While the use of spread footings cannot be precluded, their feasibility will depend on the final foundation loads, the elevation of the lowest basement, and provisions to control ground water. Prior to selecting the type of foundation and the design details, a design-level geotechnical investigation should be performed for the project, including the performance of additional borings and CPT probes. Based on preliminary analysis, driven, 14-inch square, pre-cast concrete piles are expected to develop an allowable downward capacity of 100 tons at an embedment of about 50 feet below the lowest basement level. A structural mat is anticipated to have a thickness of 5 to 6 feet. A 1.5-foot thick layer of gravel should be placed below the mat to provide uniform support. For


preliminary design, may be designed for a maximum allowable bearing capacity of about 4,000 to 5,000 psf. 5.6.2 Lateral Resistance For resistance to lateral loads, an allowable passive fluid pressure of 300 pcf above ground water and 150 pcf below water may be used. An allowable sliding friction coefficient of 0.4 may be used for design, for foundations and slabs placed in structural fill or in undisturbed, firm native soils. These values include a factor of safety of about 1.5 and both passive and sliding resistance may be used in combination without reduction. The lateral capacity of piles will depend on the type and dimensions of the pile selected and the size of pile caps. We can calculate lateral pile capacities when this information is known. 5.6.3 Settlement An excavation of 20 to 30 feet will remove about 2,400 psf to 3,600 psf of overburden pressure. We estimate that for a contact pressure of 5,000 psf, the total settlement for the structural mat will be less than 2 inches, provided the site preparation and foundation design/construction are performed in accordance with our recommendations. Properly installed piles should settle less than ¼ inch. The settlement of pile caps will be larger, with the settlement dependent on the number of piles in the cap. We can calculate the estimated settlement when the final design is completed. The majority of the settlement is anticipated to occur during or shortly after application of structural loads. The potential for post construction seismic settlements are discussed in Section 6.5.1. 5.6.4 Basement Slab Concrete floor slabs may be supported on a properly prepared subgrade. To reduce the potential for moisture transmission through the slab, we recommend that a Visqueen moisture barrier be placed under the slab prior to the placement of concrete. The moisture barrier should be sandwiched between two layers of sand, each with a minimum thickness of 2 inches. Care should be taken not to puncture the moisture barrier during construction, and any utility penetrations should be properly sealed. Unless an underfloor drain system is installed under the basement slab or mat, its design will need to consider hydrostatic uplift pressures. A discussion of design


options for considering ground water is provided in the following Section. 5.6.5 Design For Hydrostatic Pressures If a structural mat is used, the mat could be designed to resist hydrostatic uplift and the lower basement wall designed to resist lateral hydrostatic pressures. If piles are used, the floor slab could be designed as a structural slab and piles used to resist uplift. If either of these options is used, dewatering will be required during construction, but no dewatering would be required after construction. However the slab/mat should be underlain by a waterproof membrane. In addition, the lower basement wall will need to be designed for hydrostatic pressures. If the slab is not designed for up lift and the walls are not designed for hydrostatic pressures, an underfloor drain system should be used under the basement floor slab. The drainage system would consist of a minimum 12-inch thick layer of permeable gravel (such as Caltrans Permeable Material). Before placing the gravel, the subgrade should be sloped to carry water to perforated pipes. The pipes should carry flow by gravity to a sump equipped with a float-activated pump to raise and pump the water to proper disposal. The pipes should be installed with the perforations down and should be wrapped with geotextile filter fabric, such as Mirafi 140, or equivalent. During the design-level geotechnical investigation, further assessment should be made of the ground water conditions at the site; and, this information used to select the size and horizontal spacing of the pipes and the size of the pump. 5.7 Basement Walls 5.7.1 Static Pressures Basement walls should be designed as rigid walls for an equivalent fluid pressure of 55 pcf for level ground. This pressure assumes that there is no build-up of hydrostatic pressures. To account for adjacent traffic loading, the wall height should be increased by 2 feet, when calculating lateral pressures for design. If basement walls are designed for hydrostatic pressure, below the ground water table an equivalent fluid pressure of 90 pcf should be used. 5.7.2 Seismic Pressures During an earthquake an additional lateral earth pressure will be applied to basement walls. Experience has shown that walls adequately designed for static loading have generally performed well during earthquake loading.


However, if walls are to be designed for seismic loading, the magnitude of the seismic pressure can be evaluated using the procedures developed by Mononobe-Okabe (Seed and Whitman, 1970), which considers that the seismic pressure is approximated using a lateral pressure coefficient of 0.75 times an effective ground acceleration. The effective ground acceleration is taken as equal to 0.67 times the maximum expected ground acceleration. For this project, the PGA for a 475-year return interval is 0.67g. On this basis, the effective ground surface acceleration is 0.45g. Therefore, considering a soil unit weight of 125 pcf, we recommend using an equivalent fluid pressure of 42 pcf to calculate the lateral seismic pressure. The resultant of the seismic pressure should be applied at a height 0.6 times the wall height above the base of the wall. The structural engineer may want to consider the use of a lower factor of safety in evaluating the seismic design of walls, due to the temporary nature of the loading. 5.7.3 Backfilling In areas where shoring is used and backfill is required in narrow spaces between the poured wall and the shoring, cement slurry may be used in lieu of compacted backfill. However, drainage provisions must still be provided. In local areas where backfill can be placed, we recommend that any backfill placed within 10 feet of the basement/pit walls should be non-expansive granular soils with a Plastic Index (PI) of less than 15 and with less than 15 percent fines (clay/silt) passing the No. 200 sieve. The top two feet of backfill behind the walls should consist of fine-grained site soils. A discussion of waterproofing and drainage requirements is provided in the following section. The onsite sandy soils may be used as wall backfill. The use of heavy compaction equipment adjacent to basement walls can cause excessively high lateral soil pressures to be exerted on the wall. Therefore, only hand operated compaction equipment should be used within 5 feet of the walls. 5.7.4 Waterproofing and Drainage Provisions should be provided to prevent hydrostatic pressures from developing on buried walls and to protect the walls from moisture. A commercial composite drain material, such as Miradrain 6000, or equivalent, can be installed vertically between all soldier piles. If layers with seeping water are encountered in the walls of the excavation, additional drain strips should be installed horizontally to pickup the flow and bring it to the vertical drains. The drain material should be carried to the toe of the excavation and wrapped


around a perforated drain placed outside the structure wall. The drainpipe should extend around the outside of the wall and carry flow to a sump. It is recommended that the drainpipe for the wall should not be tied into the underfloor drain system, but may connect directly into a common sump, using a solid pipe. If the lower portions of basement walls are designed for hydrostatic pressures, the wall drainage may stop at that point, with appropriate details provided to convey the water to the sump. We recommend that all basement walls should be waterproofed. The finished surface adjacent to the wall should be graded to drain away from the walls. 5.8 Site Drainage And Infiltration The site should be graded to maintain positive drainage, so all runoff is properly collected and conveyed to proper disposal in approved storm drains or drainage devices. The area around the building should be sloped to drain runoff away and prevent ponding of water. The use of infiltration for storm runoff treatment is not considered practical at this site. The planned structure will essentially cover the entire site. The ground water level was found in one of the borings at 24 feet. Therefore, the 2 to 3-level basement planned will extend near or below the ground water. In addition, the soils near the basement level include 5-foot thick interbedded layers of clay, which have a very low infiltration rate. 5.9 Soil Expansive Potential A representative sample of the upper 20 feet of soil encountered in Boring B-2 was tested to identify its expansive characteristics. The test result indicated the tested soil has a very low expansion potential. 5.10 Soil Corrosivity A representative sample of the soils encountered in the upper 20 feet in Boring B-2 were tested to evaluate corrosion characteristics. The results indicate the test sample had a pH of 7.16; a water-soluble sulfate content of 0.012 percent by weight and a soluble chloride content of 220 ppm. The sulfate results indicate that sulfate exposure is classified as moderate. The tested sample was also found to have a minimum measured electrical resistivity of 3,200 Ohm-cm. The following correlation can generally be used between electrical resistivity and corrosion potential:


Elect. Resistivity Ohm-cm Corrosion Potential

less than 1,000 Severe 1,000-2,000 Corrosive 2,000-10,000 Moderate greater than 10,000 Mild On the basis of the laboratory testing, the test sample is classified as having a moderate corrosive potential for buried metals. It is recommended that additional corrosivity testing should be performed during the design-level geotechnical investigation. 5.11 Environmental Issues Evaluation of environmental issues for this project and their impact on site development are outside the scope of our work and are the responsibility of the project environmental consultant. 6.0 GEOLOGICAL HAZARD EVALUATION AND SEISMIC DESIGN

COEFFICIENTS 6.1 Ground Surface Rupture The site is not located within an Alquist-Priolo Earthquake Fault Zone, and appears to fall just north of a City of Los Angeles Fault Rupture Study Area (City Of Los Angeles, 1996). No known active faults are mapped as crossing the site or projecting towards the site in the geologic literature reviewed. The closest active fault is the Hollywood fault, which is located a distance of about 0.3 miles north of the site and is considered capable of generating a magnitude (MW) 6.4 earthquake. The upper Elysian Park and Puente Hills blind thrust faults are located below the site a depth of 1.8 and 3.5 miles, respectively. None of these faults pose a surface rupture potential to the site. On this basis, ground rupture due to faulting is not considered a significant hazard at the site. 6.2 Ground Motion The Probabilistic Seismic Hazard Maps provided by the California Geologic Survey (http://www.consrv.ca.gov/CGS/rghm/pshamap/pshamap.asp) indicate that the peak ground acceleration with a 10 percent probability of exceedance in 50 years for the general area (mean return period of 475 years) is 0.55g, for soft rock and alluvium.


The USGS Seismic Hazard De-aggregation maps indicate that for the same return period, the peak ground acceleration for soft rock is about 0.56g. The De-aggregated predominant earthquake magnitude (MW) is 6.5. 6.2.1 Probabilistic Seismic Hazard Analysis We performed an analysis of the probabilistic seismic parameters for the Design Basis Earthquake (DBE). The DBE is defined as having a ground motion with a 10 percent probability of being exceeded in 50 years. The return periods for the DBE are 475 years. For the probabilistic analysis, the computer program FRISKSP (2000) was used, considering a 60-mile radius extending out from each site. The Compton and Lower Elysian Park thrust faults were eliminated from the database and the Upper Elysian Park and Puente Hills blind thrust faults were added to the database to be in conformance with the current California Geological Survey (CGS) 2002, California Fault Parameters. The Puente Hills thrust was divided into three segments per Shaw and Shearer, 1999. In our probabilistic analysis, the following three attenuation relationships were used. Equal weight was assigned for each model, and the results were averaged.

1. Abrahamson & Silva (1997) 2. Sadigh & Others (1997) 3. Boore & Others (1997) (soil shear wave velocity of 310 m/sec.)

The use of three attenuation relationships is consistent with the general standard of practical and provides an unbiased assessment without the inherent bias associated with using only a single data set. 6.2.2 Seismic Ground Motions Results are shown in Appendix C. The computed maximum peak acceleration for the Design Basis Earthquake is 0.67g. For comparison, the 1998 Seismic Hazard Map of the CDMG, Hollywood 7.5-minute Quadrangle, shows the peak ground acceleration at the site as 0.5g for the maximum probable event (with 10% exceedance in 50 years for alluvium conditions). The computed acceleration is higher, since the CDMG map does not consider the current locations of the Puente Hills and Elysian Park thrust faults. For this project an acceleration of 0.67g should be used for the Design Basis Earthquake.


6.3 Seismic Coefficients For seismic analysis of proposed structures in accordance with the seismic provisions of the California Building Code (CBC, 2001), the site is located in Seismic Zone 4, and a Seismic Zone Factor of 0.4 should be used. The other seismic design parameters are provided in the following table.

Factor Reference Soil Profile Type Sd Table 16 J DBE Ground Acceleration 0.57g FRISKSP Seismic Source Type B Table 16U Seismic Coefficient N a 1.30 Table 16 S Seismic Coefficient Nv 1.60 Table 16 T Seismic Coefficient Ca 0.57 Table 16 Q Seismic Coefficient Cv 1.02 Table 16 R

The UBC response spectra, shown in Figure 16A-3 of UBC 1997, may be used for the analysis. This response spectrum is also provided in Table 1 in Appendix B. 6.4 Secondary Seismic Effects Potential secondary seismic effects from earthquakes for any site could include liquefaction and associated ground deformations, slope instability, tsunami and seiches, and ground lurching. These and other geologic hazards, as they relate to this site, are discussed below. 6.4.1 Liquefaction and Seismic Settlement Liquefaction involves the sudden loss in strength of a saturated, cohesionless soil (predominantly sand) caused by the build-up of pore water pressure during cyclic loading, such as produced by an earthquake. This increase in pore water pressure can temporarily transform the soil into a fluid mass, resulting in vertical settlement and can also cause lateral ground deformations. Typically, liquefaction occurs in areas where there are loose sands and the depth to groundwater is less than 50 feet from the surface. Seismic shaking can also cause soil compaction and ground settlement without liquefaction occurring, including settlement of dry sands above the water table. The site is not located within a State of California Seismic Hazard Liquefaction zone. It does fall within an area identified in City of Los Angeles Safety Element as being susceptible to liquefaction (being underlain with recent alluvial deposits and ground at less than 30 feet deep). The subsurface soil profile at the site consists of interbedded layers of sand, silt and clay. The sandy layers were generally medium


dense to dense, and had a SPT N-value typically ranging from 17 to 30Below a depth of about 45 feet the N-values ranged from 31 to 50+. The clay layers were very stiff to hard, with SPT N-values of 17 to 32 and a measured shear strength of 3,000 to 3,500 psf. We have performed a preliminary evaluation of liquefaction potential of the site, using the N-values from our borings, using the methods developed by Seed and others (Seed et al., 1985; Youd and Idriss, 1997). We considered a peak ground acceleration from the Design Basis Earthquake (with 10% probability of exceedance in 50 years) of 0.67g. Ground water was considered to be at either 24 or 44 feet. The results of our analyses are presented in Appendix D and indicate that during the Design Basis Earthquake some liquefaction is possible within the various sandy layers underlying the site. Using procedures after Tokimatsu and Seed (1987), the maximum liquefaction settlement is on the order of about 0.9 inch, with water at 24 feet, and about 0.3 inch, with water at 44 feet. The maximum differential settlement across the structure is anticipated to be less than 0.5 inch. No loss of bearing is expected to occur under planned foundations. We recommend that further evaluation of the potential for liquefaction to occur at the site during strong ground shaking should be performed as part of the design-level geotechnical investigation, using data developed from Cone Penetration Test (CPT) probes, which should be performed in addition to additional borings. 6.4.2 Slope Instability The existing topography of the site is relatively flat with no existing slopes. The site is not located within a State Earthquake Induced Slope Instability Hazard Zone (Hollywood Quad, 1998). Should any cut or fill slopes be planned, they should be reviewed. However, properly engineered slopes should be stable and seismic slope stability should not be an issue. 6.4.3 Tsunami and Seiches Potential All low-lying areas along California’s coast are subject to potentially dangerous tsunamis. Tsunamis are long-period waves generated primarily from distant and local submarine earthquakes, landslides, or volcanic eruptions. The site is at an average elevation of approximately 400 feet and is located about 12 miles from the coast. Therefore, the potential for a tsunami is not a consideration for this site. There are no bodies of water such as reservoirs, lakes and/or ponds near the site. Therefore, the potential for seiches or flooding from a body of water is


also not a consideration. 6.4.4 Ground Lurching Ground lurching usually develops during seismic events along cliffs, ridges, stream banks and/or along the ridge of artificial embankments. The general topography and soil conditions in the area indicate there is a low risk from ground lurching. 6.4.5 Flood Hazard Flood hazard potential for the site was evaluated using the ESRI/FEMA Project Impact Hazard Site Map. The site is located outside the limits of the 100-year and 500-year return-period flood. 6.4.6 Oil Field Gas Potentials The site is located about 1-1/2 miles north of the Salt Lake Oil Field, so the potential for oil field gases to exist at the site are low. 6.4.7 Other Geologic Hazards Or Considerations The site is in a zone that has been classified as having a moderate radon potential. The site is not in a known volcanic eruption area. Since the site is in an old commercial neighborhood, asbestos from fireproofing, household chemicals, lead from paint, total petroleum hydrocarbons from cars and/or pesticides could be present, and abandoned septic systems could also be encountered during site development. 7.0 POST INVESTIGATION GEOTECHNICAL SERVICES Post investigation geotechnical services will be required during project design and construction. It is recommended that GDC review the project plans and specifications prior to finalization. During construction, the site earthwork should be performed under the observation and testing of the project geotechnical engineer. This includes, demolition, removals, excavation, review of shoring design plans, installation and testing of shoring, subsurface drainage systems, proof-rolling, placement of compacted fill and backfill, installation of piles (if required) and footing/mat excavations.


8.0 LIMITATIONS The conclusions and recommendations contained in this report are professional opinions, intended for the use of the 6230, LLC, and their design consultants. This report has been prepared solely for the design of the improvements described herein, and may not contain sufficient information for other uses. The recommendations are preliminary and a design level investigation is important and necessary prior to development of the final design. These preliminary recommendations should not be extrapolated to areas not covered by this report, or used for other facilities without the review and approval of GDC. If this report, or portions of this report, are provided to contractors, or included in specifications, it should be understood that they are provided for information only. Our investigation and evaluations were performed in accordance with generally accepted local standards using that degree of care and skill ordinarily exercised under similar circumstances by reputable geotechnical consultants practicing in this or similar localities. No other warranty, expressed or implied, is made as to the professional advice included in this report. The recommendations for this project are, to a high degree dependent upon proper quality control of grading and foundation installation. Consequently, the recommendations are made contingent on the opportunity of GDC to observe grading operations and subgrade preparation. If parties other than GDC are engaged to provide such services, they must be notified that they will be required to assume complete responsibility for the geotechnical phase of the project by concurring with the recommendations in this report or provide alternate recommendations as deemed appropriate.


9.0 REFERENCES Blake, T. F., 2000, "FRISKPS Version 4-A Computer Program for the Probabilistic Prediction of Peak Horizontal Acceleration from Digitized California Faults," 1988-2000. Boore, D.M., Joyner, W.B. and Fumal, T.E., 1997, Empirical near-source attenuation relationships for horizontal and vertical components of peak ground acceleration, peak ground velocity, and pseudo-absolute acceleration response spectra: Seismological Research Letters, v. 68, p. 154-179. California Building Code (CBC), 2001, published by International Conference of Building Officials, Whittier, California. California Department of Conservation, Division of Mines and Geology, 1998, “Seismic Hazard Evaluation of the Hollywood 7.5-Minute Quadrangle, Los Angeles County, CA,” OFR 98-17. California Department of Conservation, Division of Mines and Geology, 1990, “Fault-Rupture Hazard Zones in California, Alquist-Priolo Special Studies Zones Act of 1972,” Special Publication 42, Department of Conservation, California Division of Mines and Geology. California Department of Conservation, Division of Mines and Geology, 2003, “The revised 2002 California Probabilistic Seismic Hazard Maps, June 2003, Appendix A, 2002 California Fault Parameters. Campbell, K.W., 1997, Attenuation relationships for shallow crustal earthquakes based on California strong motion data: Seismological Research Letters, v. 68, p. 180-189. Department of City Planning Los Angeles, California, “Safety Element Of The City Of Los Angeles,” City Plan Case No. 95-0371, Council File No. 86-0662, adopted November 26, 1996. ESRI/FEMA, Project Impact Hazard Site, www.esri.com/hazards/makemap.html Pacific Section AAPG, 1958, Guide to the Geology and Oil Fields of the Los Angeles and Ventura Regions, Ed, J. Higgins, AAPG-SEPM Annual Meeting 3/10-13/58. Group Delta Consultants, Inc., “Geotechnical Feasibility Study for Site Acquisition, 6230 Yucca Street, Hollywood, California, GDC Project No.: L-656R,” dated July 20, 2006.


Martin, G.R., and Lew, M. (Editors), 1999, “Recommended Procedures for Implementation of DMG Special Publication 117, Guidelines for Analyzing and Mitigating Liquefaction Hazards in California,” Organized through the Southern California Earthquake Center (SCEC), University of Southern California, March 1999, pp. 17-21. Sadigh, K., Chang, C. Y., Egan, J.A., Makdisi, F. and Youngs, R.R., 1997, SEA96—A new predictive relation for earthquake ground motions in extensional tectonic regimes: Seismological Research Letters, v. 68, p. 190-198.

Seed, R.B., Harder, L.F., 1991, “SPT Based Analysis of Cyclic Pore Pressure Generation and Undrained Residual Strength”, Seismic Short Course, Evaluation and Mitigation of Earthquake Induced Liquefaction Hazards, Los Angeles, February 4&5, 1991.

Seed, H.B., Tokimatsu, K., Harder, L.F., and Chung, R.M., 1985, “Influence of SPT Procedures in Soil Liquefaction Resistance Evaluations,” Journal of Geotech. Eng. Div., ASCE, Vol. 111, No. 12. Tokimatsu, K. and Seed, H.B., 1987, “Evaluation of Settlements in Sands Due to Earthquake Shaking,” J. of Geotech. Eng. Division, ASCE, Vol. 113, No. 8. Working group on California Earthquake Probability, “Seismic Hazards in Southern California: Probable Earthquakes, 1994-2024”, Bulletin of the Seismological Society of America, Vol. 85, No. 2, pp. 379-439, April, 1995. Yerkes et al, 1965, “Geology, Los Angeles, California – An Introduction”, Geological Survey Professional Paper, 420-A. Youngs, R.R., Chiou, S.-J., Silva, W.J. and Humphrey, J.R., 1997, Stochastic point-source modeling of ground motions in the Cascadia Region: Seismological Research Letters, v. 68, p. 74-85. Ziony, J.I., Editor,1985, "Evaluating Earthquakes in the Los Angeles Region--An Earth Science Perspective", United States Geological Survey Professional Paper 1360.

FIGURES

VICINITY MAP

Group Delta Consultants, Inc.Project Number: L-718Project Name: 6230 Yucca St.Hollywood, CA Figure 1Date: 11/20/2006

Project Site

APPENDIX A FIELD EXPLORATION

APPENDIX A FIELD EXPLORATION

The subsurface conditions at the site were investigated on October 25 and 26, 2006. The exploration program included drilling 2 borings at the locations of explorations shown on Figure 2. The borings were drilled to a depth of about 60 feet below the existing grade, using truck-mounted hollow-stem auger drilling equipment. The explorations were performed under the continuous technical supervision of our field engineer, who also maintained detailed logs of the soils encountered, classified the materials, and assisted in obtaining soil samples. Subsurface materials encountered in the borings were visually classified and logged in accordance with the Unified Soil Classification System (USCS). Boring logs are presented in Figures A-2 and A-3. A Legend for the boring logs is presented in Figure A-1. Relatively undisturbed samples alternated with Standard Penetration Tests (SPT) samples were taken in the borings at depth intervals of 5 feet, or less. In addition, representative bulk samples were taken within the upper 20 feet. The locations of samples are indicated on the logs. The drive samples were obtained with a 3-inch O.D. split-barrel sampler lined with 1-inch-high brass rings. The sampler was driven into the soil using a 140-pound hammer falling a distance of 30 inches. The number of blows required to drive the sampler 12 inches into the soil is recorded on the boring logs. The Standard Penetration Tests (SPT) was conducted in accordance with ASTM D 1586, using a standard 2-inch outside diameter, 1.375-inch inside diameter, split-spoon sampler. The SPT sampler was driven into the soil using a 140-pound hammer free-falling 30 inches. The N-value blow counts are shown directly on the boring logs. All samples were sealed to prevent moisture loss and returned to our laboratory for additional visual examination and laboratory testing. A discussion of the laboratory testing program, including test results, is provided in Appendix B. The following are attached and complete this appendix: Figure A-1 Legend for Log of Test Borings Figures A-2 and A-3 Log of Borings

APPENDIX B LABORATORY TESTING

APPENDIX B

LABORATORY TESTING

B.1 General Laboratory testing was performed to aid in the classification of soils encountered in the borings and to evaluate their physical properties and engineering characteristics. A description of the laboratory testing program is provided below. The laboratory testing is supplemented by the results of Standard Penetration Test (SPT) sampling conducted in the borings, which provide additional means to evaluate in situ soil properties such as density, shear strength and compressibility. B.2 Moisture Content and Dry Unit Weight

The field moisture and dry unit weight of the relatively undisturbed sample were determined in general accordance with ASTM D2216. Results of these tests are presented on the boring logs, and are used to evaluate existing overburden pressures and for correlation. B.3 Grain Size Distribution Representative samples were dried, weighed, soaked in water until individual soil particles were separated, and then washed on the No. 200 sieve. The portion of the material retained on the No. 200 sieve was then run through a standard set of sieves in accordance with ASTM Test Method D422. Results from these tests are presented graphically in Figure B-1. B.4 Atterberg Limit Tests To aid in the classification of fine-grained soils, Atterberg Limit tests were performed. These tests include Liquid Limit and Plastic Limit tests, which are used to determine the Plasticity Index. The tests were performed in accordance with ASTM Test Method D4318. Test results are illustrated in the Plasticity Chart shown in Figure B-2, Atterberg Limits. B.5 Consolidation The consolidation characteristics of the foundation soils were evaluated by performing one-dimensional consolidation in general accordance with ASTM Test Method D2435-90, using a floating ring consolidometer and dead weight system. The consolidation data provides evaluation of the soil pre-consolidation pressure and compression indices for evaluating post-development settlements. Results of the tests are presented in Figures B-3 and B-4, Consolidation Tests.

Preliminary Geotechnical Report November 17, 2006 Proposed High Rise Residential Development Page B-2 6230 Yucca Street, Hollywood, CA GDC Project No. L-718

B.6 Direct Shear Tests Direct shear tests were performed on selected samples in accordance with ASTM Test Method D3080. After the initial weight and volume measurements were made, the sample was placed in a calibrated shear machine and a selected normal load was applied. Each sample was then flooded and allowed to consolidate, and then were sheared under a constant strain to failure. Shear stress and sample deformations were monitored throughout the test. The test results are presented graphically in Figure B-5. B.7 Expansion Potential A representative sample of the soils encountered in the upper 20 feet, was tested for its expansion potential, according to ASTM D-4829-95. The test result indicated that the soil tested had a very low expansion potential, Expansion Index of 1. B.8 Soil Corrosivity Corrosivity testing was performed on a representative sample of the soils taken above a depth of 20 feet, and included soil pH (EPA method 150.1/9045), water-soluble chlorides (Caltrans Test method 422), water-soluble sulfates (Caltrans Test Method 417) and electrical resistivity. The test results are summarized in the following table. Table B-1 Soil Corrosivity Sample Chlorides Sulfates Minimum Resistivity Boring Depth, feet pH ppm -%- ohm-cm B-2 6 - 20 7.16 220 0.012 3,200 Notes: 1. Soil Resistivity, Chlorides, and Sulfates tests were performed by GeoLogic Associates. 2. Chlorides (Caltrans 422), Sulfates (Caltrans 417) and pH (ASTM G-5177) The following figures are attached and complete this appendix: Figure B-1 Grainsize Distribution Figure B-2 Atterberg Limits Figures B-3 & B-4 Consolidation Data Figures B-5 Direct Shear Test Results

0

10

20

30

40

50

60

70

80

90

100

0.0010.010.1110100

8

DEPTH (ft)25.040.040.0

0.240.6630.535

4

GD

C_G

RA

IN_S

IZE

L-7

18 Y

UC

CA

.GP

J G

DC

_WLO

G.G

DT

11/

22/0

6

20

U.S. SIEVE NUMBERS

coarse

BORING

U.S. SIEVE OPENING IN INCHES

(SC/CL) Reddish Brown, Clayey Sand/Sandy Clay(SM) Reddish Brown, Silty Sand

(SM) Dark Brown, Silty Sand

medium

SYMBOL

B-1B-1B-2

0.2710.146

COBBLES

40

9.52519

Cc

3/8

PE

RC

EN

T FI

NE

R B

Y W

EIG

HT

(%)

6

BORING DEPTH (ft)B-1B-1B-2

D30 D10

3/4

GRAIN SIZE IN INCHES

161.52 106

D60SYMBOL

SAND

100

25.040.040.0

GRAIN SIZE DISTRIBUTION(ASTM D 422)

PLD100 Cu

HYDROMETER

GRAVEL

3 60

coarse

30

LL

USCS CLASSIFICATION

fineSILT OR CLAY

PI

fine

2004

GD

C_G

RA

IN_S

IZE

L-7

18 Y

UC

CA

.GP

J G

DC

_WLO

G.G

DT

11/

22/0

6

FIGURE B-1GROUP DELTA CONSULTANTS, INC.

Project Name: Proposed Residential Development

Location: 6320 Yucca St. Hollywood, CA

Project No.: L-718

0

10

20

30

40

50

60

0 20 40 60 80 100

BORING DEPTH (ft) LL PL PI LI w% USCS CLASSIFICATION

35.0 34 14 20 (CL) Lt. Reddish Brown, Silty Clay

SYMBOL

ATTERBERG LIMITS

PLA

STIC

ITY

IND

EX

MH or OH

LIQUID LIMIT

CL CH

ML or OLMLCL-ML

B-1

Project: Proposed Residential Development


Number: L-718FIGURE B-2

GROUP DELTA CONSULTANTS, INC.

GD

C_A

TTE

RB

ER

G L

-718

YU

CC

A.G

PJ

GD

C_W

LOG

.GD

T 1

1/22

/06

0

1

2

3

4

5

60.1 1 10 100

NORMAL STRESS (KSF)

Dry Density (pcf)

VoidRatio

0.410

CONSOLIDATION TEST

STR

AIN

(%)

INITIAL

MoistureContent (%)

FINAL

(ASTM D-2435)

PercentSaturation (%)

119.5

Specific Gravity: 2.7

67.910.3

Remark: SAMPLE SATURATED AT 2 KSF

FIGURE B-3



Project No.: L-718GROUP DELTA CONSULTANTS, INC.

DESCRIPTIONB-1 (ML/SC) Sandy Silt/Clayey Sand

PlasticLimitSYMBOL

20.0DEPTH (ft)BORING

LiquidLimit

GD

C_C

ON

_STR

L-7

18 Y

UC

CA

.GP

J G

DC

_WLO

G.G

DT

11/

22/0

6

0

1

2

3

4

5

60.1 1 10 100

NORMAL STRESS (KSF)

Dry Density (pcf)

VoidRatio

0.716

CONSOLIDATION TEST

STR

AIN

(%)

INITIAL

MoistureContent (%)

FINAL

(ASTM D-2435)

PercentSaturation (%)

98.2

Specific Gravity: 2.7

16.24.3

Remark: SAMPLE SATURATED AT 4 KSF

FIGURE B-4



Project No.: L-718GROUP DELTA CONSULTANTS, INC.

DESCRIPTIONB-2 (SP/SM) Silty Sand

PlasticLimitSYMBOL

25.0DEPTH (ft)BORING

LiquidLimit

GD

C_C

ON

_STR

L-7

18 Y

UC

CA

.GP

J G

DC

_WLO

G.G

DT

11/

22/0

6

0

2

4

6

8

10

0 2 4 6 8 10

degMC %Before

cKSFlb/ft^3

MC %After

8.15.55.5

SH

EA

R S

TRE

SS

(Ksf

)

NORMAL PRESSURE (Ksf)

8.15.55.5

0.050.130.25

35.631.032.3

DIRECT SHEAR TEST

NOTE: All samples submerged unless otherwise notedShear Strength are Ultimate with less than 0.25 inch deflection.

Project: Proposed Residential Development


Number: L-718FIGURE B-5

GROUP DELTA CONSULTANTS, INC.

DESCRIPTIONSYM BORING Depth(ft)10.06.015.0

(SM) Reddish Brown, Silty Sand(SM/ML) Dk. Brown, Sandy Silt/Silty Sand(SM) Light Brown, Silty Sand

B-1B-2B-2

GD

C_D

IRE

CT_

SH

EA

R_A

LL_U

LT L

-718

YU

CC

A.G

PJ

GD

C_W

LOG

.GD

T 1

1/22

/06

APPENDIX C SEISMIC DATA

APPENDIX D PRELIMINARY LIQUEFACTION ANALYSIS