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HomeMy WebLinkAboutRW080076 - SOILSR0Oe0o'► GEOTECHN/CAL INVESTIGATION, PROPOSED SINGLE-FAMILY RESIDENCE, 56 SHORERIDGE, LOT 45, TRACT 15604, PELICAN CREST, NEWPORT COAST, COUNTY OF ORANGE, CA PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Orange County / Environmental / Corporate 3185-A Airway Avenue Costa Mesa, California 92626 T: 714 549 8921 F: 714 549 1438 May 31, 2005 J.N. 248-05 PAUL AND JACKIE KAMIN 400 Morningstar Lane Newport Beach, CA 92660 past + present + future it's in our science Engineers, Geologists Environmental Snientists Subject: Geotechnical Investigation, Proposed Single -Family Residence, 56 Shoreridge, Lot 45, Tract 15604, Pelican Crest, Newport Coast, County of Orange, California. References: See Attached List. Dear Mr. and Mrs. Kamin: Petra Geotechnical , Inc. (Petra), is pleased to submit herewith our geotechnical investigation report for the subject property. This work was performed in accordance with the scope of work outlined in our Proposal No. 1111-05, dated March 4, 2005. This report presents the results of our field investigation, laboratory testing, and our engineering judgment, opinions, conclusions and recommendations pertaining to geotechnical design aspects of the proposed development. This investigation also included a review of published and unpublished literature and geotechnical maps with respect to active faults located in proximity to the site which may have an impact on the seismic design of the proposed structure. It has been a pleasure to be of service to you on this project. Should you have any questions regarding the contents of this report, or should you require additional information, please do not hesitate to contact us. Respectfully submitted, David Hansen Associate Engineer 1 rt Orange County / r. San Diego County r1 Riverside County r. Los Angeles County rt San Bernardino County r• Desert Region Environmental / Corporate 12225 World Trade Drive, Suite P 38655 Sky Canyon Drive, SuiteA 26639 Valley Center Drive, Suite 109 3535 Inland Empire Blvd., Suite 35 42-240 Green Way, Suite E 3185-A Airway Avenue San Diego, California 92128 Murrieta, California 92563 Santa Clarita, California 91351 Ontario, California 91764 Palm Desert, CA 92211 Costa Mesa, California 92626 858-485-5530 951-600-9271 661-255-5790 909-941-2505 760-340-5303 714-549-8921 TABLE OF CONTENTS Page INTRODUCTION 1 TRANSFER OF RESPONSIBILITY 1 SITE LOCATION AND DESCRIPTION 2 BACKGROUND INFORMATION 2 GRADING PLAN REVIEW 4 Proposed Construction 4 Proposed Grading 4 SITE RECONNAISSANCE AND SUBSURFACE EXPLORATION 5 LABORATORY TESTING 6 FINDINGS 6 Geology and Subsurface Conditions 6 Groundwater 7 Faulting 7 CONCLUSIONS AND RECOMMENDATIONS 9 General Grading Plan Review 9 Site/Slope Stability 9 Effect of Proposed Grading on Adjacent Properties 10 Seismic -Induced Hazards 10 Primary Geotechnical Concerns 11 Slope Creep 11 Structural Setbacks 12 Earthwork 13 General Earthwork and Grading Specifications 13 Site Clearing 13 Ground Preparation 13 Fill Placement and Testing 14 Stability of Temporary Excavation Sidewalis 14 Post -Grading Considerations 15 Site Drainage 15 Utility Trench Backfill 16 Seismic Considerations 18 Ground Motions 18 Secondary Seismic Hazards 20 Foundation Design Recommendations 21 Foundation Setbacks 21 Allowable Soil Bearing Capacities 22 Settlement 23 Lateral Resistance 23 Minimum Footing and Floor Slab Recommendations 24 Soluble Sulfate Analysis and Soil Corrosivity 27 Retaining Wall Design Recommendations 28 Allowable Bearing Capacity and Passive Resistance 28 TABLE OF CONTENTS (Continued) Page Active and At -Rest Earth Pressures 28 Subdrainage and Waterproofing 30 Wall Backfill 31 Masonry Block Wall Recommendations 32 Construction on Level Ground 32 Construction Along the Top of the Rear Yard Descending Slope 33 Swimming Pool and Spa Construction 36 General Comments 36 Structural Setback 36 Allowable Bearing and Lateral Earth Pressures 37 Subdrainage 38 Stability of Temporary Excavations 38 Temporary Access Ramps 39 - Pool and Spa Bottoms 39 Pool and Spa Decking 39 Plumbing Fixtures 39- Exterior Concrete Flatwork 40 Thickness and Joint Spacing 40 Reinforcement 40 Subgrade Preparation 40 Edge Beams (Optional) 41 Outdoor Fireplace 41 LONG-TERM EFFECT OF SOIL EXPANSION AND SLOPE CREEP 41 FUTURE IMPROVEMENTS 42 REPORT LIMITATIONS 43 - REFERENCES LITERATURE REVIEWED APPENDIX A EXPLORATION LOGS APPENDIX B LABORATORY TEST PROCEDURES LABORATORY TEST DATA PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 1 GEOTECHNICAL INVESTIGATION, PROPOSED SINGLE-FAMILY RESIDENCE, 56 SHORERIDGE, LOT 45, TRACT 15604, PELICAN CREST, NEWPORT COAST, COUNTY OF ORANGE, CALIFORNIA INTRODUCTION This report presents the results of our geotechnical investigation of the subject property based on the enclosed 8-scale site plan prepared by EBTA Architects (Plate 1). The purposes of this investigation were to determine the nature of surface and subsurface - soils, to evaluate their in -place characteristics, and to provide geotechnical recommendations with respect to site grading, and for design and construction of building foundations and other site improvements. This study also includes a review of published and unpublished literature and - geotechnical maps with respect to active and potentially active faults located in proximity to the site which may have an impact on the seismic design of the proposed structure. TRANSFER OF RESPONSIBILITY The referenced geotechnical reports and corresponding plans prepared by Leighton & Associates, Inc. have been reviewed with respect to subsurface soil and geologic conditions within the site, and we generally concur with the findings, conclusions and recommendations presented therein. As of the date of this report, we assume responsibility for all future geotechnical work within our purview to be performed within the subject site. PAUL AND JACKIE KAMIN SITE LOCATION AND DESCRIPTION May 31, 2005 J.N. 248-05 Page 2 The subject lot, designated as Lot 45 of Tract 15604, consists of a building pad that is presently vacant and is located at 56 Shoreridge in the Newport Coast area of Orange County, California (see Figure 1). The irregular -shaped lot is bordered on the northeast and southwest by existing residences, on the northwest by Shoreridge, and on the southeast by an approximately 110- to 125-foot-high, 2:1 to 3:1(horizontal to vertical) slope that descends to Newport Coast Drive. Ground surface elevations across the building pad range from approximately 654 to 658 feet above mean sea level, creating a maximum vertical relief of approximately 4 feet. Drainage across the building pad is by sheet flow to the western corner of the lot where surface water is collected by an existing storm drain inlet. The building pad is currently covered by a sparse to moderate growth of weeds and grasses. The descending slope to the southeast of the lot is covered with a moderate to thick growth of landscape and natural vegetation consisting of grasses, weeds, groundcover, shrubs and trees. An above -ground sprinkler system provides irrigation to the slope. Manmade features presently at the site consist of utility stubouts near the street curb on Shoreridge, the storm drain inlet located at the western corner of the lot, and 5- to 6- foot-high masonry block walls along the northeast and southwest property lines. BACKGROUND INFORMATION Rough grading of Tract No. 15604 was performed between April and August of 1995 when the tract was designated as Tract 15091. This grading was performed with geotechnical observation, testing, and mapping services provided by Leighton & LOCATION MAP Ref: State of California Seismic Hazard Zones Map; NEWPORT BEACH QUADRANGLE Base Map prepared by U.S. Geologic Survey and dated 1965 (Photorevised 1981), Official Map Released April 15, 1998, Scale: 1 inch = 2000 feet PETRA GEOTECHNICAL, INC. J.N. 248-05 MAY, 2005 FIGURE 1 PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 3 Associates, Inc. (Leighton, 1996). This original phase of grading consisted of the construction of building pads for custom homes and associated access streets and included the removal of all unsuitable surficial materials, construction of buttresses and stabilization fills, installation of subdrains, and construction of retaining walls and Loffelstein walls. In 1997, minor regrading and erosion repair was also performed under the purview of Leighton and Associates, Inc. (Leighton, 1997c). This phase of grading also included the removal of several masonry walls within the tract. The most recent grading occurred between June and August of 1998 under the purview of Leighton and Associates, Inc. (Leighton, 1998c) and consisted of minor regrading in order to increase the size of the lots within the tract. At that time, the tract was re- designated as Tract 15604. Table C-1 of the rough grade report for Tract 15604 (Leighton, 1998c) indicates that the subject site (Lot 45) is a fill lot with fill depths ranging from approximately 5 to 37 feet. Within the majority of the lot, these fill materials are underlain by terrace_ deposits and then by bedrock materials of the Monterey Formation. However, within the southeastern portion of the lot, these fill materials are underlain directly by bedrock materials of the Monterey Formation. The Leighton report indicates that on -site terrace deposits consist predominantly of clayey sands that are slightly expansive with negligible sulfates. The Monterey Formation bedrock materials were reported to consist of interbedded siliceous and non -siliceous siltstones and clayey siltstones with interbeds of clayey diatomaceous siltstone and fine sandstone. According to the rough grade report, bedding within the Monterey Formation in the vicinity of the subj ect site generally strikes in a northwesterly direction and dips towards the northeast at inclinations of approximately 33 to 60 degrees. The variations in dip angles were reported to be due to local minor folding and faulting of the bedrock. The geologic units and bedrock structure beneath the site are shown on the enclosed grading plan, Plate 1. PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 4 The rough grade report also indicates that compacted fill materials underlie the adjacent southeasterly descending slope. The upper portion of this slope is supported by an approximately 20- to 30-foot-wide by 10-foot-deep fill key that was excavated into older engineered fill materials and bedrock. The lower portion of this slope is a buttress fill that is composed of older engineered fill materials that were placed as part of the grading of Newport Coast Road. GRADING PLAN REVIEW Proposed Construction The enclosed site plan prepared by EBTA Architects (Plate 1), indicates that a two- story, single-family residence with two attached garages is proposed within the subject lot. It is our understanding that the residence will be of woodframe construction with the lowermost floor slabs constructed on -grade. Other improvements proposed within the site consist of a swimming pool and spa in the rear yard, various masonry block walls within the yard areas, a retaining wall within the northeastern side yard, an outdoor fireplace, and extensive exterior concrete flatwork (i.e., walkways, patios, stairways, and driveway). Proposed Grading The enclosed site plan, Plate 1, indicates that the first floor of the residence is proposed at an elevation of approximately 654 feet above mean sea level. Based on this elevation, cuts of approximately 1 to 3 feet will be required to reach planned finish pad grades within the limits of the residence. Cuts of only a few inches up to approximately 2 feet will be required in the front yard and southwestern side yard while cuts of approximately 2 to 6 feet will be required to reach proposed grades within the northeastern side yard and to construct the retaining wall proposed along the PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 5 side of this northeastern side yard. Cuts of approximately 2.5 to 4.5 feet will also be required within the rear yard; however, locally deeper cuts will be required in the area of the proposed swimming pool and spa. The depths of these cuts will depend on the actual depths of the pool and spa which are not shown on the site plan. It is expected that a drainage system will be designed for the site to collect surface runoff and direct it to the existing storm drain located in the western corner of the building pad. It is expected that this drainage system will consist of area drains, earth swales and sheet flow gradients in landscape areas, and sloped concrete flatwork. SITE RECONNAISSANCE AND SUBSURFACE EXPLORATION A site reconnaissance was performed by a representative of this firm on April 8, 2005 (on the same day that we performed our subsurface exploration). Our reconnaissance - consisted of the visual evaluation of the building pad and adjacent slope. Existing surface conditions within the site and surrounding areas, as observed during our site reconnaissance, were described previously in the "Site Location and Description" section of this report. Our subsurface exploration involved the drilling of two exploratory borings with a bucket -auger drill rig to depths of 21 to 26 feet below existing ground surfaces. Soil and bedrock materials encountered were visually classified and logged in general accordance with the Unified Soil Classification System and the Engineering Geology Field Manual by the U.S. Department of the Interior, Bureau of Reclamation, respectively. The approximate locations of the exploratory borings are shown on the enclosed site plan, Plate 1, and descriptive "Exploration Logs" of the borings are presented in Appendix A. PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 6 Associated with our subsurface exploration was the collection of bulk and relatively undisturbed samples of artificial fill, terrace deposits and bedrock for laboratory testing. The undisturbed samples were obtained using a 3-inch, outside diameter, modified California split -spoon soil sampler lined with 1-inch-high brass ring liners. The central portion of the driven core samples were placed in sealed containers and transported to our laboratory for testing. LABORATORY TESTING To evaluate the engineering properties of site soils, several laboratory tests were performed on selected samples of fill, terrace deposits and bedrock considered representative of those encountered. Laboratory tests included the determination of maximum dry density, expansion potential, soluble sulfate content, pH, resistivity and Atterberg limits. A description of laboratory test criteria and summaries of the test data are presented in Appendix B. Moisture content and unit dry density were also determined for the in -place fill, terrace deposits and bedrock materials in representative - strata. These test data are included in the `Exploration Logs," Appendix A. An evaluation of the test data is reflected throughout the "Conclusions and Recommendations" section of this report. FINDINGS Geology and Subsurface Conditions Fill materials were encountered within our exploratory borings B-1 and B-2 to depths of 7 and 19 feet below the existing ground surface, respectively. These fill materials were observed to consist of moist, stiff, sandy clays with occasional layers of moist, dense clayey sands although the upper 8 to 12 inches of these materials were observed to be medium dense (firm) and desiccated due to the processes of weathering and root growth. Depths of fill within the site as observed within our exploratory borings are in PAUL AND JACKTF KAMIN May 31, 2005 J.N. 248-05 Page 7 general agreement with the fill depths provided in the geotechnical report of rough grading (Leighton, 1998). Terrace deposits were encountered below the fill materials within boring B-1 at a depth interval of 7 to 11 feet below the existing ground surface. Terrace deposits were not encountered within boring B-2. These deposits consist of clayey sand and were observed to be moist, dense, and fine- to medium -grained. Bedrock materials were encountered within borings B-1 and B-2 at depths of 11 and 19 feet below the existing ground surface, respectively. The bedrock materials consist of siliceous and non -siliceous siltstones and clayey siltstones and were noted to be slightly moist, moderately hard to hard, thinly bedded and moderately fractured. The geologic structure of the bedrock underlying the site as well as the elevations of the bottoms of the remedial removals (as mapped by both Leighton during rough grading and by Petra during our recent subsurface exploration) are shown on the enclosed site - plan, Plate 1. Groundwater Groundwater was not encountered within our exploratory borings, at least to the maximum depth explored (26 feet). Furthermore, based on our experience in the area, static groundwater is anticipated to exist at a depth greater than 100 feet below the existing ground surface. Faulting Based on our review of published and unpublished geotechnical maps and literature pertaining to site and regional geology, the site is located approximately 2.9 miles or 4.7 kilometers to the northeast of the offshore segment of the Newport -Inglewood PAUL AND JACKTE KAMIN May 31, 2005 J.N. 248-05 Page 8 fault. The Newport -Inglewood fault consists of a series of parallel and en -echelon, northwest -trending faults and folds extending from the southern edge of the Santa Monica Mountains southeast to the offshore area of Newport Beach. This zone has a history of moderate to high seismic activity and has generated numerous earthquakes greater than magnitude 4.0, including the March 11, 1933 magnitude 6.3 Long Beach earthquake which was centered offshore of Newport Beach. At the time of the 1933 earthquake, secondary effects of strong ground shaking were noted in the Long Beach and Huntington Beach areas (i.e., sand boils, ground cracking and liquefaction). In addition, subsurface fault displacement of several inches was associated with the October 21,1941 earthquake (magnitude 4.9), and with the June 18, 1944 earthquake (magnitude 4.5), both of which occurred along the onshore segment of the Newport - Inglewood fault in the Dominguez Hills area (Barrows, 1974). In addition, the California Geologic Survey (CGS) has recently revised the California Probabilistic Seismic Hazard Maps to include the San Joaquin Hills blind thrust fault - as a potentially active Type B fault (Cao. et. al., 2003). Based on our evaluation, the subject site lies directly above the fault plane of this blind thrust fault. Based on our review of the referenced geologic maps and literature, no active or potentially active faults are known to project through the property. Furthennore, the site does not lie within the boundaries of an "Earthquake Fault Zone" as defined by the State of California in the Alquist-Priolo Earthquake Fault Zoning Act. PAUL AND JACK KAMIN May 31, 2005 J.N. 248-05 Page 9 CONCLUSIONS AND RECOMMENDATIONS General From a soils engineering and engineering geologic point of view, the subject property is considered suitable for the proposed grading and construction provided the following conclusions and recommendations are incorporated into the design criteria and project specifications. Grading Plan Review This report has been prepared without the aid of a precise grading plan depicting the proposed grading and construction and is based on the enclosed site plan prepared by the project architect (Plate 1). As such, the recommendations provided in this report should be considered tentative until a finalized precise grading plan is available and reviewed by the project geotechnical consultant. Additional recommendations and/or modification of the recommendations provided herein may be necessary depending upon the results of our precise grading plan review. Site/Slope Stability The building pad area and the southeasterly descending slope beyond the rear yard property line are composed of compacted fill materials supported at depth by competent native terrace deposits and bedrock. The upper portion of the descending slope is supported by a 20 - to 30-foot-wide by 10-foot-deep keyway while the lower portion of the slope consists of a buttress fill that was placed during the grading of Newport Coast Drive. The descending slope exhibits no evidence of surficial slumping nor any evidence of gross instability such as tension cracks at the top and/or bulging within the face of the slope. In addition, as previously described, the descending slope is landscaped and supplied with above -ground irrigation. Based on PAUL AND JACKTF I AMIN May 31, 2005 J.N. 248-05 Page 10 all of these conditions, the rear yard descending slope is considered to be both grossly and surficially stable and is expected to remain so under normal conditions provided the existing surface drainage systems and landscaping are properly maintained during the lifetime of the development. Effect of Proposed Grading on Adjacent Properties It is our opinion that the proposed grading and construction will not adversely affect the stability of adjoining properties provided that grading and construction are performed in accordance with the recommendations presented herein. Seismic -Induced Hazards Based on our review of the Seismic Hazard Zones map for the Laguna Beach Quadrangle, the site is situated on the easterly side of a former northwest -southeast - trending ridge flanked by a northeasterly facing natural slope that descended down to_ Los Trancos Canyon. This former natural slope was included within an Earthquake - Induced Landslide Zone by the State Geologist (see Figure 1); however, the mass grading that was performed to construct Newport Coast Drive and Tract 15604 has essentially eliminated the previously existing topography that was mapped by the State Geologist within the area of the subject site. As a result, the subject site is now located within the east -central portion of Tract 15604 and consists of a graded building pad that is bordered on the east by a 2:1 to 3:1 graded slope which descends a vertical distance of approximately 110 to 125 feet to Newport Coast Drive. On the other side of Newport Coast Drive lies Los Trancos Canyon. This canyon is located within the area that has been mapped as an Earthquake -Induced Hazard Zone by the State Geologist. PAUL AND JACK KAMIN May 31, 2005 J.N. 248-05 Page 11 All of the natural slopes that affect Tract 15604 were addressed by Leighton & Associates through extensive geotechnical investigations for the subject tract and surrounding areas. Earthquake -induced hazard zones, where present on the natural slopes, generally encompass locally oversteepened slopes, slopes with adverse bedding orientations, and slopes with existing mapped landslides. These zoned areas were mitigated by Leighton & Associates by the removal of unsuitable landslide debris, construction of canyon fills, and construction of buttress and stabilization fills where needed. In Leighton's rough grade report for Tract 15604 (Leighton, 1998c), reference was made to several reports that provide documentation that the slopes surrounding and supporting Tract 15604 are in compliance with PRC Section 2697 and CCR Title 14, Section 3724. Their report concluded that their investigations, design and earthwork performed during grading comply with PRC Section 2697 and CCR, Title 14, Section 3724. Leighton has submitted copies of this report, as well as extra copies of all of their previous reports that are relevant to Tract 15604, to the County of Orange Planning and Development Services Department for their review and submittal to the State oversight agency. These reports were recently approved by the County, and Tract 15604 is in compliance with PRC Section 2697 and CCR Title 14, Section 3724. Primary Geotechnical Concerns Slope Creep The fill materials that comprise the building pad and adjacent rear yard descending slope are slightly to moderately expansive. As a result, the probability exists for development of a creep condition on the fill slope with the passage of time. Creep is an imperceptibly slow, nearly continuous downward and outward movement of slope soils. PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 12 Creep cannot be stopped or eliminated; however, a proper footing design can be provided such that proposed top -of -slope structures will not be adversely affected by slope creep. In general, a slope creep condition developing to a depth of approximately 5 feet deep can be anticipated on the rear yard descending slope. Therefore, structures proposed in the site and within approximately 15 feet of the top of the rear yard slope may need to be supported on either deepened footings or caissons in order to mitigate the potential adverse effects of slope creep. Based on the enclosed preliminary grading plan, Plate 1, the proposed residence is setback a sufficient distance from the top of the slope such that the foundations are not expected to be affected by slope creep. However, the swimming pool and spa and the rear yard top -of -slope block wall are proposed within close proximity of the descending rear yard slope and may need to be supported on either deepened footings or caissons to mitigate the adverse effects of slope creep. Recommendations for design - and construction of the foundations for these structures are provided in subsequent sections of this report. Structural Setbacks It is proposed to construct the southeasterly walls of the residence within approximately 20 to 35 feet of the top of the adjacent descending slope and the southeasterly walls of the pool and spa are proposed within approximately 1 to 3 feet of the top of the adjacent descending slope. Based on the height of the adjacent descending slope (in excess of 120 feet), Section 1806.5.3 of the Uniform Building Code requires a minimum footing setback of 40 feet for the building while Section 1806.5.4 requires a minimum footings setback of 20 feet for the pool and spa. Therefore, the setbacks shown on the plans are a deviation from the setback codes. PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 13 Since the site is considered to be both grossly and surficially stable, it is our professional opinion that the proposed setbacks of the residence from the adjacent descending slope as shown on the current site plan (20 to greater than 30 feet) are adequate to provide proper vertical and lateral support of the residence. In addition, it is our opinion that a horizontal setback of at least 15 feet between the outside bottom edge of the top -of -slope structures and the face of the adjacent slope will provide proper vertical and lateral support of these structures. However, since these recommendations are a deviation from the UBC code which states that a minimum - setback of 40 feet should be used for the building and 20 feet for the pool and spa and other top -of -slope structures, a waiver request package will be processed through the County of Orange Planning and Development Services Depaittuent for approval by the Building Official. Earthwork General Earthwork and Grading Specifications All earthwork and grading should be performed in accordance with all applicable requirements of the Grading and Excavation Code and the Grading Manual of the County of Orange, California, in addition to the recommendations presented below. Site Clearing Any significant vegetation within areas of proposed grading and construction should be stripped and removed from the site. Ground Preparation Near surface fill materials within the site were found to be moist, but medium dense (firm) and desiccated in the upper 8 to 12 inches, while the underlying fill materials PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 14 remain moist and dense (stiff). Therefore, existing ground surfaces in all areas to receive fill should be overexcavated to a depth of at least 12 inches below the existing ground surfaces, watered or air dried as necessary to achieve optimum or above optimum moisture conditions, and then replaced as properly compacted fill with a minimum relative compaction of 90 percent. This procedure should also be followed in all areas to remain at existing grade, and in shallow cut areas where the depth of cut is less than 12 inches. If, during grading, the depth of surficial desiccation is found ter be greater than 12 inches, the depth of overexcavation should be increased accordingly. Fill Placement and Testing All fill should be placed in 6-inch-thick maximum lifts, watered or air dried as necessary to achieve optimum or above -optimum moisture conditions, and then compacted in place to a minimum relative compaction of 90 percent. The laboratory maximum dry density and optimum moisture content for each change - in soil type should be determined in accordance with Test Method ASTM D 1557-02. A representative of the project geotechnical consultant should be present on -site during grading operations to verify proper placement and adequate compaction of all fill, as well as to verify compliance with the other geotechnical recommendations presented herein. Stability of Temporary Excavation Sidewalls During site grading, a temporary excavation with sidewalls varying from approximately 2 to 6 feet in height will be created along the northeast side of the site during the construction of the proposed retaining wall. The sidewalls of the temporary excavation are expected to expose compacted fill materials. Based on the physical PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 15 characteristics of the onsite fill materials, temporary slopes not exceeding a height of approximately 5 feet may be tentatively planned at a vertical gradient. However, where excavations exceed this height, the lower 5 feet may be cut vertical and the upper portions above a height of 5 feet should be cut back at a maximum gradient of 1:1, horizontal to vertical, or flatter. Temporary slopes excavated at the above slope configurations are expected to remain stable during construction; however, the temporary excavations should be observed by a representative of the project geotechnical consultant for any evidence of potential instability. Depending on the results of these observations, revised slope configura- tions inay be necessary. Other factors which should be considered with respect to the stability of temporary slopes include construction traffic and storage of materials on or near the tops of the - slopes, construction scheduling, presence of nearby walls or structures, and weather conditions at the time of construction. All applicable requirements of the California Construction and General Industry Safety Orders, the Occupational Safety and Health Act of 1970, and the Construction Safety Act should also be followed. Based on our review of the enclosed conceptual grading plan, there appears to be sufficient room to cut back the sidewall of the excavation at the above recommended slope configuration. Post -Grading Considerations Site Drainage A surface drainage system consisting of a combination of sloped concrete flatwork, earth swales and sheet flow gradients in landscape areas, and a surface yard drain system should be designed for the site. The drainage system should drain by gravity PAUL AND JACIUE KAMIN May 31, 2005 J.N. 248-05 Page 16 flow to a suitable discharge point. The purpose of this drainage system will be to reduce water infiltration into the subgrade soils and to direct surface waters away from building foundations, walls and slope areas. In addition, the following recommenda- tions for drainage should be implemented during construction. 1. Area drains should be extended into planters and landscape areas that are located within 5 feet of building walls, retaining walls and masonry block walls to mitigate excessive infiltration of water into the foundation soils. The ground surface within these planter areas and landscape areas should also be sloped at a minimum gradient of 2 percent away from the walls and foundations. 2. Concrete flatwork surfaces and sloped ground surfaces should be inclined at a minimum gradient of 1 percent away from building foundation and similar structures. A minimum 12-inch- high berm should be maintained along the top of all descending slopes to prevent any water from flowing over the slopes. The subdrains behind the proposed retaining walls should either drain by gravity flow to the proposed surface drainage system or, if the subdrains lie below the elevations of the inlets of the proposed area drains they should be routed to a sump equipped with a properly designed pumping system that is capable of elevating the accumulated water to the area drain system. 3. A watering program should be implemented for the landscaped areas that maintains a uniform, near optimum moisture condition in the soils. Overwatering and subsequent saturation of the soils may cause excessive soil expansion and heave and should thus be avoided. On the other hand, allowing the soils to dry out may cause excessive soil shrinkage. As an alternative to a conventional irrigation system, drip irrigation is strongly recommended for all planter areas. The owner is advised that all irrigation and drainage devices should be properly maintained throughout the lifetime of the development. Utility Trench Backfill All utility trench backfill should be compacted to a minimum relative compaction of 90 percent. On -site earth materials cannot be densified adequately by flooding and jetting techniques. Therefore, trench backfill materials should be placed in lifts no greater than approximately 12 to 18 inches in thickness, watered or air-dried as t_I PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 17 necessary to achieve optimum or above optimum moisture conditions, and then mechanically compacted in place to a minimum relative compaction of 90 percent. A representative of the project geotechnical consultant should probe and test the backfills to verify adequate compaction. As an alternative for shallow trenches where pipe or utility lines may be damaged by mechanical compaction equipment, such as under building floor slabs, imported clean - sand exhibiting a sand equivalent (SE) value of 30 or greater may be utilized. The sand backfill materials should be watered to achieve optimum or above optimum moisture conditions and then tamped into place. No specific relative compaction will be required; however, observation, probing, and if deemed necessary, testing should be performed by a representative of proj ect geotechnical consultant to verify an adequate degree of compaction and that the backfill will not be subject to settlement. Where utility trenches enter the footprint of the building, they should be backfilled- through their entire depths with on -site fill materials rather than with any sand or gravel shading. This "plug" of on -site soil will mitigate the potential for water to migrate beneath the foundations and floor slabs. Where an exterior and/or interior utility trench is proposed in a direction that parallels a building footing, the bottom of the trench should not extend below a 1:1 plane projected downward from the bottom edge of the adjacent footing. Where this condition occurs, the adjacent footing should be deepened or the utility be constructed and the trench then backfilled and compacted prior to constructing the footing. PAUL AND JACKIE KAMIN Seismic Considerations Ground Motions May 31, 2005 J.N. 248-05 Page 18 Structures within the site should be designed and constructed to resist the effects of seismic ground motions as provided in Sections 1626 through 1633 of the 1997 Unifoiiii Building Code (UBC). The method of design will be dependent on the seismic zoning, site characteristics, occupancy category, type of structural system, and on the building height. For structural design in accordance with the 1997 UBC, a computer program devel- oped by Thomas F. Blake (UBCSEIS, 1998) was used that compiles fault infoiiiiation for a particular site using a modified version of a data file of approximately 183 California faults that were digitized by the California Department of Mines and Geology and the U.S. Geological Survey. This program computes various information for a particular site including the distance of the site from each of the faults in the data file, the estimated slip -rate for each fault, and the "maximum moment magnitude" of each fault. The program selects the closest Type A, Type B, and Type C faults from the site and computes the seismic design coefficients for each of the fault types. The program then selects the largest of the computed seismic design coefficients and designates these as the design coefficients for the subject site. Based on our evaluation, the offshore segment of the Newport -Inglewood Fault Zone (approximately 2.9 miles or 4.6 kilometers to the southwest of the site) would probably generate the most severe site ground motions with a maximum moment magnitude of 6.9 and a slip rate of 1.5 mm/year. The following UBC (1997) seismic design coefficients are based on the soil profile type that will exist at the completion of proposed grading and on the proximity of the site to the Newport -Inglewood fault. PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 19 Table 1 1997 UBC Seismic Parameters Based on Newport -Inglewood Fault 16-I Seismic Zone Factor Z 0.40 16-J Soil Profile Type SD 16-Q Seismic Coefficient Ca 0.46 16-R Seismic Coefficient Cy 0.80 16-S Near -Source Factor Na 1.0 16-T Near -Source Factor N„ 1.3 16-U Seismic Source Type As described previously, the California Geologic Survey (CGS) has recently revised the California Probabilistic Seismic Hazard Maps to include the San Joaquin Hills blind thrust fault as a potentially active Type B fault (Cao. et. al., 2003). Since the San Joaquin Hills blind thrust fault has a relatively shallow dip and is located only approximately 2 to 8 kilometers below the ground surface, the Maps of Known Active Fault Near -Source Zones Maps.... (ICBO, 1998) indicate that the distance from this fault to the subject site should be designated as 0 km. The seismic parameters based on the San Joaquin Hills Thrust fault being located 0 km. from the subject site are provided below. Table 2 1997 UBC Seismic Parameters Based on the San Joaquin Hills Blind Thrust Fault 16-I Seismic Zone Factor Z 0.40 16-J Soil Profile Type Sd 16-Q Seismic Coefficient Ca 0.57 16-R Seismic Coefficient C,, 1.02 16-S Near -Source Factor Na 1.3 16-T Near -Source Factor Ny 1.6 16-U Seismic Source Type PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 20 However, we have recently contacted the CGS about whether the revised 2002 seismic sources (including the San Joaquin Hills Thrust fault) should actually be used in the 1997 UBC seismic codes. Mr. Bill Bryant, Senior Geologist with the CGS replied back to us that based on the way these blind thrusts were probabilistically modeled, the design ground motions either only marginally exceeded (<10%) or were less than the 1997 UBC design ground motions with Na = Nv =1.0 and that the blind thrust faults in the 1996 and 2002 PSHA models were weighted only between 25% and 50% because of the large uncertainties with respect to location, geometry, and rates of activity. Based on this information, we recommend that the project architect and project structural engineer review the seismic parameters provided previously based on both the Newport -Inglewood (Table 1) and San Joaquin Hills blind thrust (Table 2) faults, The selection of seismic parameters should be determined by them and discussed with the owner. Secondary Seismic Hazards Secondary effects of seismic activity nonnally considered as possible hazards to a site include several types of ground failure as well as induced flooding. Various general types of ground failures which might occur as a consequence of severe ground shaking of the site include landsliding, ground subsidence, ground lurching, shallow ground rupture and liquefaction. The probability of occurrence of each type of ground failure depends on the severity of the earthquake, distance from faults, topography, subsoils and groundwater, conditions, in addition to other factors. Based on our subsurface exploration, all of the above types of ground failure are considered unlikely at the site. PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 21 Seismically induced flooding which might be considered a potential hazard to a site normally includes flooding due to a tsunami (seismic sea wave), a seiche, or failure of a major reservoir retention structure upstream of the site. Since the site lies several miles away from and more than 650 feet above the Pacific Ocean, and does not lie in close proximity to an enclosed body of water, and since it does not lie downstream of a major reservoir retention structure, the probability of flooding from a tsunami, seiche or dam break inundation is considered nonexistent. Foundation Design Recommendations Foundation Setbacks Based on the enclosed site plan, Plate 1, it is proposed to construct the southeasterly walls of the residence within approximately 20 to 35 feet of the top of the adjacent descending slope. Based on the height of the adjacent descending slope (in excess of 120 feet), Section 1806.5.3 of the Uniform Building Code requires a minimum footing. setback of 40 feet for the building. Therefore, the setbacks shown on the plans are a deviation from the setback codes. Since the site i.s considered to be both grossly and surficially stable, it is our professional opinion that the proposed setbacks of the residence from the adjacent descending slope as shown on the current site plan (20 to greater than 30 feet) are adequate to provide proper vertical and lateral support of the residence. However, since these recommendations are a deviation from the UBC code which states that a minimum setback of 40 feet should be used for the building, a waiver request package will need to be processed through the County of Orange Planning and Development Services Department for approval by the Building Official. This waiver request package will be provided by our firm at a later date. PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 22 As described previously, a slope creep condition developing to a depth of approximately 5 feet deep can be anticipated on the descending rear yard slope. On the l basis of this anticipated condition, structures proposed along the top of the descending slope may need to be supported on either deepened footings or caissons in order to 11 mitigate the potential adverse effects of slope creep. Furthermore, the UBC states that a horizontal structural setback equivalent to one -six of the total slope height (to a maximum of 40 horizontal feet) is required between the outside bottom edges of proposed pools or spas and the face of the adjacent descending slope. Therefore, for the subject site that is bordered by an approximately 110 to 125-foot-high slope, the UBC indicates that a structural setback of at least 20 feet is required for top -of -slope pools and spas. The enclosed site plan indicates that the pool, spa and rear property line wall are proposed near the top of the rear yard descending slope and, therefore, should be supported on either deepened footings or caissons to mitigate the adverse effects of slope creep. Based on the enclosed site plan and minimum pool and spa setback requirements, it is recommended that a minimum horizontal setback of at least 20 feet be maintained between the outside bottom edge of the foundations of these structures and the face of the adjacent descending slope. This recommended setback will extend the foundations below the potential creep zone and will meet the minimum setback requirements of the UBC. Allowable Soil Bearing Capacities Provided that remedial grading is performed within the site as recommended previously, an allowable bearing value of 1,500 pounds per square foot is recommended for design of 24-inch-square pad footings and 12-inch-wide continuous footings founded at a minimum depth of 12 inches into competent fill materials. This PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 23 value may be increased by 20 percent for each additional foot of width and/or depth, to a maximum value of 2,500 pounds per square foot. Recommended allowable bearing values include both dead and live loads, and may be increased by one-third when designing for short duration wind and seismic forces. Although the above recommended allowable soil bearing capacities are based on 12- inch-deep footings, on -site soil materials are slightly to moderately expansiver. Therefore, to mitigate the effects of expansive soils and to comply with the minimum requirements of the 1997 UBC, footing depths in excess of 12 inches will be required for the proposed structure. Specific recommendations for design and construction of building foundations are presented in the "Footing and Floor Slab Recommendations" section of this report. Settlement At the completion of proposed grading, the building will be underlain by approximately 7 to 20 feet of compacted fill materials and then by dense, native terrace deposits and/or bedrock materials. Based on these anticipated fill depths, maximum total long-term settlement of the existing fill materials is expected to be approximately %2 to 3/4 of an inch with a differential settlement of approximately 1/4 of an inch over a horizontal span of 20 feet. The majority of this estimated settlement will occur during construction or shortly thereafter as the loads are applied. Lateral Resistance A passive earth pressure of 250 pounds per square foot, per foot of depth, to a maximum value of 2,500 pounds per square foot may be used to determine lateral bearing resistance for footings. A coefficient of friction of 0.35 tunes the dead load forces may be used between concrete and the supporting soils to determine lateral fl1 r, PAUL AND JACK KAMIN May 31, 2005 J.N. 248-05 Page 24 sliding resistance. The above values maybe increased by one-third when designing for short duration wind or seismic forces. The above values are based on footings placed directly against compacted fill. In the case where footing sides are formed, all backfill placed against the footings should be compacted to at least 90 percent of maximum dry density. Minimum Footing and Floor Slab Recommendations Results of our laboratory test indicate on -site fill and terrace materials exhibit a MEDIUM expansion potential, as classified in accordance with Table 18-I-B of the 1997 UBC. The 1997 UBC specifies that slab -on -ground foundations resting on soils with an expansion index greater than 20 require special design considerations in accordance with Section 1815. The design procedures outlined in Section 1815 are based on the weighted plasticity index of the different soil layers existing within the - upper 15 feet of the building site. Therefore, a plasticity index of 25 was determined for a sample of on -site soil considered to be the most representative of the fill materials beneath the site. This plasticity index is considered to be the appropriate weighted plasticity index for the building site in accordance with UBC Section 1815.4.2. However, Section 1815.4.2 also states that the weighted plasticity index of the building site must be modified (multiplied) by correction factors that compensate for the effects of sloping ground and the unconfined compressive strength of the onsite soils. Since the site consists of a level pad, the weighted plasticity index value does not need to be corrected for the effects of sloping ground. Furthermore, in order to approximate the unconfined compressive strength of the on -site fill and native materials, penetration tests with a pocket penetrometer were performed on several undisturbed samples of onsite fill and native terrace deposits that were obtained during our subsurface exploration of the site. The unconfined compressive strength of the onsite materials PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 25 ranged from approximately 2.0 to greater than 4.5 tsf (4 to greater than 9 ksf). Based on these unconfined compressive strengths, it is recommended that the weighted plasticity index (25) be multiplied by a factor of 1.2 in order to determine the value of the effective plasticity index (per Figure 18-111-2 of the 1997 UBC). In summary, an effective plasticity index of 30 should be used for the site in accordance with Section 1815.4.2 of the 1997 UBC. The design and construction recommendations that follow are based on the above soi/ conditions and may be considered for minimizing the effects of moderately expansive soils and long-term differential settlement. These recommendations have been developed on the basis of previous experience of the project geotechnical consultant on projects with similar soil conditions. Although construction performed in accordance with these recommendations has been found to minimize post -construction movement. and/or cracking, they generally do not positively mitigate all potential effects of expansive soils and future settlement. The effective plasticity index provided above should be utilized by the project structural engineer to design slab -on -ground foundations with an interior grade beam grid system in accordance with Section 1815. Based on this design, thicker floor slabs, larger footing sizes and/or additional reinforcement may be required and should govern the design if more restrictive than the minimum recommendations provided below: 1. Footings a. Exterior continuous footings should be founded at a minimum depth of 18 inches below the lowest adjacent final grade. Interior continuous footings may be founded at a minimum depth of 12 inches below the bottoms of the adjacent slabs. All continuous footings should have minimum widths of 12, 15, and 18 inches for one-story, two-story, and three-story construction, respectively, and should be reinforced with a minimum of four No. 4 bars, two top and two bottom. PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 26 b. Interior isolated pad footings should be a minimum of 24 inches square and founded at a minimum depth of 18 inches below the bottoms of the adjacent slabs. The pad footings should be reinforced with No. 4 bars spaced a maximum of 18 inches on centers, both ways, near the bottoms of the footings. c. Exterior isolated pad footings intended for support of roof overhangs such as second -story decks, patio covers and similar construction should be a. minimum of 24 inches square, and founded at a minimum depth of 24 inches below the lowest adjacent final grade. The pad footings should be reinforced with No. 4 bars spaced a maximum of 18 inches on centers, both ways, near the bottoms of the footings. d. The spacing and layout of the interior grade beam grid system should be determined by the project architect or structural engineer in accordance with UBC Section 1815.5 and the beams designed in accordance with UBC Section 1815.6. 2. Floor Slabs a. The project architect or structural engineer should evaluate minimum floor slab thickness and reinforcement in accordance with UBC Section 1815 based on the effective plasticity index provided previously. Unless a more stringent design is recommended by the architect or structural engineer, we recommend a minimum slab thickness of 4 inches for both living area and garage floor slabs, and reinforcement consisting of No. 3 bars spaced a maximum of 18 inches on centers, both ways. All slab reinforcement should be supported on concrete chairs or brick to ensure the desired placement near mid depth. b. Living area concrete floor slabs should be underlain with a moisture vapor retarder consisting of a polyvinyl chloride membrane such as 10-mil Visqueen, or equivalent. All laps within the membrane should be sealed, and at least 2 inches of clean sand should be placed over the membrane to promote uniform curing of the concrete. To reduce the potential for punctures, the membrane should be placed on a pad surface that has been graded smooth without any sharp protrusions. If a smooth surface cannot be achieved by grading, consideration should be given to placing a 1-inch- thick leveling coarse of sand across the pad surface prior to the placement of the membrane. PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 27 c. Prior to placing concrete, the subgrade soils below living area floor slabs should be prewatered to achieve a moisture content that is at least 1.3 times the optimum moisture content. This moisture should penetrate to a depth of approximately 18 inches into the subgrade. Soluble Sulfate Analysis and Soil Corrosivity Results of the laboratory tests performed in accordance with California Test Method No. 417 indicate on -site fill materials contain water-soluble sulfate contents of approximately 0.11 percent. Therefore, according to UBC Table 19-A-4, a MODERATE exposure to sulfate can be expected for concrete placed in contact with the on -site earth materials. The structural integrity of concrete can deteriorate with time when exposed to sulfate containing solutions or soils. To mitigate such deterioration, sulfate resistant cement should be used in all concrete that may be in contact with the on -site soils. Careful control of the maximum water -cement ratio and the minimum concrete compressive strength is also necessary in order to provide property resistance against deterioration due to sulfates. We recommend that the procedures provided in UBC Section 1904.3 and Table 19-A-4 be followed. For concrete that is expected to have a MODERATE exposure to sulfates, Type V cement should be used. In addition, Table 19-A-4 of the 1997 UBC indicates that the maximum water -cement ratio should not exceed 0.50 and the minimum concrete compressive strength should not be less than 4,000 pounds per square inch. The results of our limited in-house testing of soil pH and resistivity indicate that on - site soils are generally slightly alkaline with respect to pH (pH=7.9) while soil resistivity was found to be 520 ohm -cm and chloride content was found to be 550 ppm. The preliminary chemical test results are included in Appendix B. The results of these PAUL AND JACK KAMIN May 31, 2005 J.N. 248-05 Page 28 tests indicate that on -site soil materials may be moderately to severely corrosive to ferrous metals and copper. As such, it is recommended that additional sampling and analysis be conducted during the final stages of site grading to provide a complete assessment of soil corrosivity. Petra does not practice corrosion engineering. Therefore, we recommend that on -site soils be tested and analyzed near or at the completion of precise grading by a qualified corrosion engineer to evaluate the general corrosion potential of the on -site soils and any impact on the proposed construction. Retaining Wall Design Recommendations Allowable Bearing Values and Passive Resistance Footings for retaining walls may be designed using the allowable bearing capacity and lateral resistance values presented previously for building footings; however, when calculating passive resistance, the upper 6 inches of the footings should be ignored in areas where the footings will not be covered with concrete flatwork, or where the thickness of soil cover over the top of the footing is less than 12 inches. An increase of one-third of the above values may also be used when designing for short duration wind or seismic forces. The above values are based upon footings placed directly against compacted fill. In the case where footing sides are formed, all backfill placed against footings should be compacted to at least 90 percent of maximum dry density. Active and At -Rest Earth Pressures As of the date of this report, it is uncertain whether the proposed retaining walls on -site will be backfilled with on -site soils or imported granular materials. For this reason, active and at -rest earth pressures are provided below for both conditions. PAUL AND JACKIE KAMIN 1. On -Site Soils Used for Backfill May 31, 2005 J.N. 248-05 Page 29 On -site soils may be used as backfill behind retaining walls; however, they are slightly to moderately expansive. Therefore, if these materials are used as backfill, active earth pressures equivalent to fluids having densities of 45 and 75 pounds per cubic foot should be used for design of cantilevered walls retaining a level backfill and ascending 2:1 backfill, respectively. For walls that are restrained at the top, at -rest earth pressures of 68 and 110 pounds per cubic foot (equivalent fluid pressures) should be used. The above values are for retaining walls that have been supplied with a proper subdrain system (see Figure RW-1). All walls should be designed to support any adjacent structural surcharge loads unposed by other nearby walls or footings in addition to the above recommended active and at -rest earth pressures. 2. Imported Sand, Pea Gravel or Rock Used for Wall Backfill Where sufficient area exists behind the proposed walls, imported clean sand exhibiting a sand equivalent value (SE) of 30 or greater, or pea gravel or crushed rock may be used for wall backfill to reduce the lateral earth pressures provided these granular backfill materials extend behind the walls to a minimum horizontal distance equal to one-half the wall height. In addition, the sand, pea gravel or rock backfill materials should extend behind the walls to a minimum horizontal distance of 2 feet at the base of the wall or to a horizontal distance equal to the heel width of the footing, whichever is greater (see Figures RW-2 and RW-3). For the above conditions, cantilevered walls retaining a level backfill and ascending 2:1 backfill may be designed to resist active earth pressures equivalent to fluids having densities of 30 and 41 pounds per cubic foot, respectively. For walls that are restrained at the top, at -rest earth pressures equivalent to fluids having densities of 45 and 62 pounds per cubic foot are recommended for design of restrained walls supporting a level backfill and ascending 2:1 backfill, respectively. These values are also for retaining walls supplied with a proper subdrain system. Furthermore, as with native soil backfill, the walls should be designed to support any adjacent structural surcharge loads imposed by other nearby walls or footings in addition to the recommended active and at -rest earth pressures. All structural calculations and details for retaining walls should be provided to this firm for verification purposes prior to grading and construction phases. NATIVE SOIL BACKFILL Sloped or level ground surface Compacted on -site soil Recommended backcut* Waterproofing compound Install subdrain system Minimum 12-inch-wide column of 3/4" -1 1/2" open graded gravel wrapped in filter fabric. Filter fabric (should consist of ice+ Mirafi 140N or equivalent) 4 inch perforated pipe. Perforated pipe should consist of 4" diameter ABS SDR-35 or PVC Schedule 40 or approved equivalent with the perforations laid down. Pipe should be laid on at least 2 inches of open -graded gravel. * Vertical height (h) and slope angle of backcut per soils report. Based on geologic conditions, configuration of backcut may require revisions (i.e. reduced vertical height, revised slope angle, etc.) RETAINING WALL BACKFILL 111111111a1111111MMvwrwwaww�w/wwnw IMPORTED SAND BACKFILL Sloped or level ground surface tt On -site native soil cap '-.1...::':'•:(12" thick) Non -expansive imported sand, SE>30. Waterproofing compound Install subdrain system 1 cubic foot per foot min. of 3/4" - 1 1/2" open graded gravel wrapped in filter fabric. Filter fabric (should consist of Mirafi 140N or equivalent). 4 inch perforated pipe. Perforated pipe should consist of 4" diameter ABS SDR-35 or PVC Schedule 40 or approved equivalent with the perforations laid down. Pipe should be laid on at least 2 inches of open -graded gravel. 2' min* > *At base of wall, the non -expansive backfill materials should extend to a min. distance of 2' or to a horizontal distance equal to the heel width of the footing, whichever is greater. RETAINING WALL BACKFILL nin��.�rrw�rwnw�rn�w w�swwrr►w�av��rwi� au �w�c.' _ :-.11icA� IMPORTED GRAVEL OR CRUSHED ROCK BACKFILL 1/2 Sloped or level ground surface 0 00 oo 0 0 00 00 ° o 0 0000 0 00 OOQO 00 0 0 G 0 0 0 0 0 d w0oo 0 p o OO oO 0° 0 oo ° o 0 00 o a ° 0 ° ° /' w°o O o0 000Q0 oo°p O 0 0 0 0 v0 O Q oo°/ 0 OO 00 ° on o OO o 0 0 0 0 0 0 0 0,-- 0 coo ,'/ Install filter fabric on Mirafi 140N s oo 0 00 �_O 0 00 ,. equal) to .,.�+ gra+: o 0 0° 0 0 0 p° o o° o o� .� of fines into backfill. 00 D a Q O pOd /i 0° 0 0 0 0 0 0 o p o o Waterproofing compound 0 0 00 \ O ( 0 0 0 '!� Qoopa '0000 0 0..y� 00 0 0 0 0 0 0 0 o/\ boo ©00 0o ao• h a0000p00000 / ° 0 00 o0 0 o p 0/ � 00 00 Oo 00°/ yp p° 0000 4,0 CI9 po°0 a / lQOo� 0 00flp ° On -site native soil cap I Non -expansive imported gravel or crushed rock p o0 'Op 2' min*.-> 4 inch perforated pipe. Perforated pipe should consist of 4" diameter ABS SDR-35 or PVC Schedule 40 or approved equivalent with the perforations laid down. If pea gravel used, pipe should be encased in 1 cubic foot per foot min. of 3/4" -1 1/2" open -graded gravel wrapped in filter fabric (Mirafi 140N or equal) Pipe should be laid on at least 2 inches of gravel. *At base of wall, the non -expansive backfill materials should extend to a min. distance of 2' or to a horizontal distance equal to the heel width of the footing, whichever is greater. • RETAINING WALL BACKFILL D z _ o'D''JAI "ai' D � Ii,'ice'/ PAUL AND JACKTF KAMIN Subdrainage and Waterproofing May 31, 2005 J.N. 248-05 Page 30 Perforated pipe and gravel subdrains should be installed behind all retaining walls to prevent entrapment of water in the backfill (see Figures RW-1 through RW-3). Perforated pipe should consist of 4-inch-minimum diameter PVC Schedule 40, or ABS SDR-35, with the perforations laid down. The pipe should be encased in a 1-foot-wide column of %-inch to 11-inch open -graded gravel. If on -site soils are used as backfill, the open -graded gravel should extend above the wall footings to a minimum height equal to one-third the wall height, or to a minimum height of 1.5 feet above the footing, whichever is greater. If imported sand, pea gravel, or crushed rock is used as backfill, the open -graded gravel should extend above the wall footing to a minimum height of 1 foot above the footing. The open -graded gravel should be completely wrapped in filter fabric consisting of Mirafi 140N, or equivalent. Solid outlet pipes should be connected to the subdrains and then routed to a suitable area for discharge of accumulated water. If a limited area exists behind the walls for installation of a pipe and gravel subdrain, a geotextile drain mat such as Mirafi Miradrain, or equivalent, can be used in lieu of drainage gravel. The drain mat should extend the full height and lengths of the walls and the filter fabric side of the drain mat should be placed up against the backcut. The perforated pipe drain line placed at the bottom of the drain mat should consist of 4- inch minimum diameter PVC Schedule 40 or ABS SDR-35. The filter fabric on the drain mat should be peeled back and then wrapped around the drain line. The portions of retaining walls supporting backfill should be coated with an approved waterproofing compound or covered with a similar material to inhibit infiltration of moisture through the walls. 1 PAUL AND JACKIE KAMIN Wall Backfill May 31, 2005 J.N. 248-05 Page 31 Recommended active and at -rest earth pressures for design of retaining walls are based on the physical and mechanical properties of the on -site soils. However, since the onsite soils are expected to be moderately expansive, they may be difficult to compact when placed in the relatively confined areas located between the walls and temporary backcut slopes. Therefore, to facilitate compaction of the backfill, consideration should be given to using sand, pea gravel, crushed rock or imported granular soils that exhibit a VERY LOW expansion potential (Expansion Index of less than 20) for backfill behind the exterior retaining walls. For this condition, the reduced active and at -rest pressures provided previously. for sand, pea gravel or crushed rock backfill may be considered in the wall design, provided that they are installed as shown on Figures RW-2 and RW-3. Where adjacent building footings are proposed within the backfill area of the retaining walls, native soil backfill should be used rather than sand, gravel or rock to facilitate the excavation of the footing trenches. Where on -site soils or imported sand are used for backfill, they should be placed in approximately 6- to 8-inch-thick maximum lifts, watered as necessary to achieve optimum or above optimum moisture conditions, and then mechanically compacted in place to a minimum relative compaction of 90 percent. Flooding or jetting of the backfill materials should be avoided. A representative of the project geotechnical consultant should observe the backfill procedures and test the wall backfill to verify adequate compaction. s PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 32 If imported pea gravel or rock is used for backfill, the gravel should be placed in approximately 2- to 3-foot-thick lifts, thoroughly wetted but not flooded, and then mechanically tamped or vibrated into place. A representative of the project geo- technical consultant should observe the backfill procedures and probe the backfill to determine that an adequate degree of compaction is achieved. To mitigate the potential for the direct infiltration of surface water into the backfill, imported sand, gravel or rock backfill should be capped with at least 12 inches of on - site soil. Filter fabric such as Mirafi 140N, or equivalent, should be placed between the soil and the imported gravel or rock to prevent fines from penetrating into the backfill. Masonry Block Wall Recommendations Construction on Level Ground Footings for masonry block walls proposed on level ground may be designed in accordance with the bearing and lateral resistance values provided previously for retaining wall footings founded in fill. However, as a minimum, the wall footings should be embedded at a minimum depth of 12 inches below the lowest adjacent final grade. The footings should also be reinforced with a minimum of four No. 4 bars, two top and two bottom.. In order to minimize the potential for unsightly cracking related to the possible effects of differential settlement and/or expansion, positive separations (construction joints) should also be provided in the block walls at each corner and at horizontal intervals of approximately 20 to 25 feet. The separations should be provided in the blocks and not extend through the footings. The footings should be poured monolithically with continuous rebars to serve as effective "grade beams" below the walls. PAUL AND JACK KAMIN May 31, 2005 J.N. 248-05 Page 33 Construction Along The Top of the Rear Yard Descending Slope The enclosed site plan indicates that a masonry block wall may be constructed along the rear property line and along the top of the rear yard descending slope. This masonry block wall should be supported on footings that are deepened such that a minimum horizontal setback of 20 feet is maintained between the outside bottom edge of the footings and the face of the adjacent descending slope. This recommended setback will extend the foundations below the potential creep zone and will meet the minimum setback requirements of the UBC. Footings or caissons may be used to achieve the minimum footing setbacks. Recommendations for these deepened footings or caissons are provided below. 1. Deepened Footings: Footings for the block wall proposed along the top of the rear yard descending slope should be founded at a depth that will provide a minimum footing setback of 20 feet measured along a horizontal line projected from the outside bottom edges of the footings to the daylight contact with the slope face. It should be noted that additional footing depths may be required to resist the potential creep forces and to achieve the necessary passive resistance against lateral movement as determined by the project structural engineer based on the soil parameters provided below. Footings for block walls at the above recommended minimum setbacks may be designed using the allowable bearing values recommended previously for footings founded in compacted fill; however, when calculating passive resistance, the passive earth pressure should be reduced to 150 pounds per square foot, per foot of depth, to a maximum value of 1,500 pounds per square foot. In addition, the lateral resistance should be ignored for the upper portions of the wall footings located within the creep zone. If deepened footings are used for top -of -slope block walls, these walls will essentially become retaining walls. By constructing a continuous footing, it is anticipated that the earth materials behind the wall will no longer be able to creep past the wall and exert creep forces; however, they will exert an active earth pressure of 45 pounds per cubic foot. To mitigate the build-up of any hydrostatic pressure, a subdrain system should be installed behind the wall footings. it PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 34 2. Cast -In -Place Caissons: In lieu of deepened conventional footings, cast -in -place concrete caissons and grade beams may be used to support the walls proposed along the top of the rear yard descending slope. Specific design recommendations for the caissons and grade beams are provided below. i. Grade Beam Embedment: The tops of the grade beams may be located near the ground surface. No specific setback will be required between the outside bottom edges of the grade beams and slope face. ii. Lateral Resistance for Grade Beams: Due to downward and outward movement of the surficial soils within the creep zone, lateral resistance and bearing capacity should be ignored in design of grade beams. iii. Caisson Capacity: End bearing capacity and skin friction may be combined to deteiinine allowable caisson capacities provided the minimum caisson diameter is 18 inches. An allowable end bearing capacity of 5,000 pounds per square foot may be used for caissons embedded at least three caisson diameters below the creep zone and into compacted fill. A value of 400 pounds per square foot may be used to determine the skin friction between the concrete and the surrounding fill materials; however, when calculating skin friction, the upper portions of the caissons located within the creep zone should be ignored. iv. Passive Resistance for Caissons: A passive earth pressure of 450 pounds per foot of caisson width per foot of depth may be used to determine lateral resistance for those portions of the caissons founded in compacted fill; however, lateral resistance should be ignored for the upper portions of the caissons located within the creep zone. v. Lateral Loading: To compensate for potential creep forces, the caissons should be designed to resist a lateral load imposed by creep affected slope materials. This lateral load should be assumed to be equal to 1,000 pounds per foot of embedment in the creep zone. If the grade beams are constructed below grade and within the creep zone, an active earth pressure equivalent to a fluid having a density of 45 pounds per cubic foot should be assumed to be acting on these grade beams. However, retaining walls and other structural elements constructed on top of the caissons and above the creep prone soils will not be subject to creep forces. PAUL AND JACKTR KAMIN May 31, 2005 J.N. 248-05 Page 35 vi. Point of Fixity: The point of fixity for the caissons should be determined by the project structural engineer. However, as an approximation, the point of fixity may be assumed at a depth equal to the depth of the creep zone plus two times the caisson diameter. vii. Uplift: Caissons may be considered to resist uplift forces equal to the skin friction between the concrete caisson and the surrounding fill as described above. Allowable uplift capacity should not exceed 55 percent of the allowable downward capacity. viii. Caisson Depth and Spacing: Caisson depth and spacing should be deteitiiined by the project structural engineer based on total wall loads and lateral loading. How -ever, minimum clear spacing between caissons should be two caisson diameters, sidewall to sidewall. In addition, maximum spacing between caissons should not exceed five caisson diameters, center to center. Further, the caissons should have a minimum depth of at least three caisson diameters or 6 feet below the creep zone, whichever is greater. ix. Caisson Locations Relative to Wall: To prevent eccentric loading, the centerlines of the caissons should correspond to the centerline of the wall. x. Reinforcement: Reinforcement for caissons should be determined by the project structural engineer with regard to strengthening the concrete to resist lateral forces. xi. Geotechnical Observations: All caisson excavations should be observed by a representative of the project geotechnical consultant to verify minimum embedtnents determined by the project structural engineer. The drilled holes should also be cleared of loose materials and any construction debris prior to pouring concrete. xii. Concrete Placement: Concrete should be placed by the tremie method and not allowed to free fall to prevent segregation of the concrete, as well as scouring or erosion of the sidewalls of drilled holes. The lower end of the tremie pipe should be continually immersed in fresh concrete and slowly withdrawn as the concrete is deposited. PAUL AND JACKTR KAMIN Swimming Pool and Spa Construction General Comments May 31, 2005 J.N. 248-05 Page 36 Past history has shown that pools and spas and similar structures and their associated decking constructed in close proximity to descending slopes commonly suffer distress in the form of cracking, lifting, horizontal separations and tilting. Consequently, it is our professional opinion that the proposed pool and spa, if constructed in their currently proposed location, may experience some level of distress unless mitigating measures are taken. The pool and spa recommendations that follow are considered suitable to reduce the potential for future movement or distress of this structure; however, these recommendations should be followed in acknowledgment of the risks involved in the proposed construction adjacent to the slope. These recommendations are intended to reduce the detrimental effects of slope creep. However, it should be understood that a certain amount of cracking, as well as horizontal and vertical movement of pool and spa decking, may occur. Although a certain amount of distress may occur, it is our opinion that construction of the pool and spa will not have any adverse impact on the adjacent slope or properties provided that they are designed and constructed in accordance with our recommendations. Structural Setback The southeasterly sides of the pool and spa are proposed within close proximity of the top of the adjacent descending slope. Therefore, in order to provide adequate vertical and lateral support of the pool and spa, the southeasterly pool and spa walls should be designed as a free-standing walls that are structurally tied to the pool and spa bottoms. These walls should also be supported by deepened continuous footings or shallow caissons, as necessary, such that a minimum horizontal setback of at least 20 feet is maintained between the outside bottom edge of the footings and the slope face. This i PAUL AND JACK KAMIN May 31, 2005 J.N. 248-05 Page 37 recommended setback will exceed the recommendations of Section 1806.5.4 of the 1997 UBC and also takes into consideration the anticipated creep zone within the rear yard descending slope. These deepened footings or caissons should be designed and constructed in accordance with the recommendations provided in the "Masonry Block Wall Recommendations" section of this report. Allowable Bearing and Lateral Earth Pressures The pool and spa shells may be designed using an allowable bearing value of 1,500 pounds per square foot. In addition, the pool and spa walls should be designed assuming that an earth pressure equivalent to a fluid having a density of 45 pounds per cubic foot is acting on the outer surface of the pool walls. The free standing southeasterly walls of the pool and spa should be designed for both the short term condition in which the soil will be exerting a lateral pressure equivalent to a fluid having a density of 45 pounds per cubic foot that is acting on the outer surface of the walls, and for the potential long term condition in which the soil creeps away toward the adjacent slope and there is no soil support. For this long-teiiii condition, the walls should be designed using a lateral earth pressure of 62.4H pounds per square foot (where "H" equals the vertical depth in feet below the ground surface) that is acting on the inner surface of the pool and spa walls. Pool and spa walls should also be designed to resist lateral surcharge pressures imposed by any adjacent footings or structures in addition to the above lateral earth pressures. PAUL AND JACKIE KAMIN Subdrainage May 31, 2005 J.N. 248-05 Page 38 Due to the proximity of the pool and spa to the adjacent descending slope, there is a possibility of distress to the slope in the event of an undetected plumbing leak. Therefore, in order to prevent the possible accumulation of leaking water in the area of the slope, perforated pipe and gravel subdrains should be installed in 12-inch by 12- inch trenches excavated across the deepest parts of the pool and spa excavations. The perforated subdrain pipes should consist of 4-inch diameter ABS SDR-35 or PVC Schedule 40 pipes. Gravel placed around the perforated pipes should consist of 'A- to 1'/2-inch open -graded gravel completely wrapped with filter fabric. Filter fabric should consist of Mirafi 140N, or equal. The perforated pipes should be underlain by approximately 2 inches of the open -graded gravel and should be laid with the perforations down. The perforated pipes should be connected to 4-inch-diameter ABS SDR-35 or PVC Schedule 40 solid pipes that are routed to a suitable discharge point. The pipes should not be routed onto the face of the adjacent slope as this could result in future slope erosion and surficial soil saturation. To ensure a positive gravity flow, the perforated pipe and solid outlet pipe sections should be installed at a minimum gradient of 1 percent. Stability of Temporary Excavations The pool and spa excavations are expected to expose competent compacted fill materials. Based on the anticipated physical characteristics of these materials, the pool and spa excavation sidewalls may remain at a vertical gradient. The temporary sidewalls are expected to remain stable during construction of the pool and spa; however, the temporary excavation sidewalls should be observed by a representative of the project geotechnical consultant for any evidence of potential instability. Depending upon the results of these observations, revised sidewall slope configurations may be necessary and forming of the pool walls may be necessary. PAUL AND JACKIE KAMIN Temporary Access Ramps May 31, 2005 J.N. 248-05 Page 39 It is essential that all backfill placed within temporary access ramps extending into the pool and spa excavations be properly compacted and tested. This will mitigate excessive settlement of the backfill and subsequent damage to pool decking or other structures placed on the backfill. Pool and Spa Bottoms It is expected that the swimming pool and spa bottoms will rest entirely on compacted fill. Therefore, care should be taken while excavating these structures to prevent disturbance of subgrade soils exposed at grade in the pool and spa bottom. Pool and Spa Decking Pool and spa decking should be constructed in accordance with the recommendations presented in the "Exterior Concrete Flatwork" section of this report. Plumbing Fixtures Leakage from the swimming pool and spa or from any of the appurtenant plumbing could create adverse saturated conditions of the surrounding subgrade soils. Localized areas of oversaturation can lead to differential expansion (heave) of the subgrade soils and subsequent raising and shifting of concrete flatwork. Therefore, it is essential that all plumbing and pool fixtures be absolutely leak -free. For similar reasons, drainage from pool deck areas should be directed to local area drains and/or graded earth swales designed to carry runoff water to a suitable discharge point. PAUL AND JACKIE KAMIN Exterior Concrete Flatwork Thickness and Joint Spacing May 31, 2005 J.N. 248-05 Page 40 To reduce the potential of unsightly cracking related to the effects of moderately expansive soils, concrete sidewalks, and patio -type slabs should be at least 4 inches thick and provided with construction joints or expansion joints every 6 feet or less. Concrete subslabs to be covered with decorative pavers should also be at least 4 inches thick and provided with construction joints or expansion joints every 6 feet or less. New concrete driveway slabs, if any, should be at least 5 inches thick and provided with construction joints or expansion joints every 10 feet or less. Reinforcement Consideration should be given to reinforcing all concrete patio -type slabs, pool decking, driveways and sidewalks greater than 5 feet in width with No. 3 bars spaced 18 inches on centers, both ways. The reinforcement should be positioned near the middle of the slabs by means of concrete chairs or brick. Subgrade Preparation As a further measure to minimize cracking of concrete flatwork, the subgrade soils below concrete flatwork areas should first be compacted to a minimum relative compaction of 90 percent and then thoroughly moistened to achieve a moisture content that is at least 5 percent or greater above optimum moisture content. This moisture content should extend to a depth of 12 inches below subgrade and be maintained in the soils during placement of concrete. Pre -watering of the soils will promote uniform curing of the concrete and minimize the development of shrinkage cracks. A repre- sentative of the project geotechnical consultant should observe and verify the density PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 41 and moisture content of the soils, and the depth of moisture penetration prior to pouring concrete. Edge Beams (Optional) Where the outer edges of concrete flatwork are to be bordered by landscaping, edge beams (thickened edges) may be constructed to mitigate excessive infiltration and accumulation of water under the slabs. Edge beams should be 6 to 8 inches wide, extend 12 inches below the tops of the finish slab surfaces, and be reinforced with a minimum of two No. 4 bars, one top and one bottom. Inclusion of edge beams in flatwork construction adjacent to landscaped areas is expected to significantly reduce the potential for vertical and horizontal movement and subsequent cracking of the flatwork related to the effects of high uplift forces that can develop in expansive soils. Outdoor Fireplace The outdoor fireplace and similar structural features should be supported by either continuous footings or pad footings. The footings should be founded at a minimum of 12 inches below the lowest final adjacent grade. Continuous footings should be reinforced with four No. 4 bars, two top and two bottom, while pad footings should be reinforced with No. 4 bars spaced a maximum of 18 inches on centers, both ways, near the bottom of the footings. LONG-TERM EFFECT OF SOIL EXPANSION AND SLOPE CREEP As mentioned previously in this report, the site is underlain by fill, terrace deposits and bedrock materials that are slightly to moderately plastic and moderately expansive. Due to their inherent composition, these materials invariably exhibit the potential to undergo a certain amount of long-term volume changes such as settlement, heave, and PAUL AND JACK KAMIN May 31, 2005 J.N. 248-05 Page 42 lateral movement. When water is introduced to expansive soils by such sources as landscape irrigation, swimming pools and rainfall, the expansive soils tend to absorb an excessive amount of moisture that, in turn, causes the expansive soils to expand and heave. This heave causes an upward and lateral movement of hardscaped areas or, if the movement is restricted, causes distress and fracturing to hardscape features constructed in these areas. Expansive soils not only expand as their moisture contents increase, but also contract as their moisture contents decrease. Therefore, as a result of seasonal variations in the moisture contents, this repeated cycle of expansion and contraction causes a loss in density and shear strength. In addition, these cycles cause progressive outward and downward movement of the surficial materials located on or in close proximity to descending slopes (slope creep). This progressive outward and downward movement, in turn, may cause distress and tilting to such structures as fences, masonry block walls, retaining walls, and concrete flatwork that are constructed in these areas. Although the recommendations provided in this report are intended to reduce the potential for distress of structures resulting from the effects of expansive soils and slope creep, our experience has shown that even with the implementation of these recommendations, a certain amount of cracking and/or horizontal and vertical movements is unavoidable and can be anticipated during the lifetime of the proposed development. The homeowner should be made fully aware that the property is underlain by moderately expansive soils and that these soils will cause the concerns noted above. FUTURE IMPROVEMENTS Should any new structures or improvements be proposed at any time in the future other than those shown on the enclosed preliminary grading plan and discussed herein, our PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 43 firm should be notified so that they may provide design recommendations to minimize movement and/or tilting of the structures related to the effects of expansive soils and slope creep. Design recommendations are particularly critical for any new improvements that may be proposed on or near descending slopes, and in areas where they may interfere with the proposed permanent drainage facilities. Potential problems can develop when drainage on the pad is altered in any way (i.e., excavations or placement of fills associated with construction of new walkways, patios, garden walls and planters). Therefore, it is recommended that we be engaged to review the final design drawings, specifications and grading plan prior to any new construction. If we are not given the opportunity to review these documents with respect to the geotechnical aspects of new construction and grading, we can take no responsibility for misinterpretation of our recommendations presented herein. REPORT LIMITATIONS This report is based on the proposed project and geotechnical data as described herein. The materials encountered on the project site, described in other literature, and utilized in our laboratory investigation are believed representative of the project area, and the conclusions and recommendations contained in this report are presented on that basis. However, soil and bedrock materials can vary in characteristics between points of exploration, both laterally and vertically, and those variations could affect the conclusions and recommendations contained herein. As such, observation and testing by a geotechnical consultant during the grading and construction phases of the project are essential to confirming the basis of this report. To provide the greatest degree of continuity between the design and construction phases, consideration should be given to retaining Petra Geotechnical, Inc. for construction services. PAUL AND JACKIE KAMIN May 31, 2005 J.N. 248-05 Page 44 This report has been prepared consistent with that level of care being provided by other professionals providing similar services at the same locale and time period. The contents of this report are professional opinions and as such, are not to be considered a guarantee or warranty. This report should be reviewed and updated after a period of one year or if the project concept changes from that described herein. This report has not been prepared for use by parties or projects other than those named or described herein. This report may not contain sufficient information for other parties or other purposes. This opportunity to be of service is sincerely appreciated. Please call if you have any questions pertaining to this report. Respectfully submitted, PETRA GEOTECI LAICAL, INC. David Hanse Associate Engineer RCE 56591 DH/DR/nls W:\2005\200\248-05A. PLM.doc Darrel Roberts Principal Geologist CEG 1972 • PETRA -1 REFERENCES Leighton & Associates, Inc., 1996, Geotechnical Report of Rough Grading, Including Loffelstein Wall and Retaining Wall Construction, Planning Area 1 C-2, Tract 15091, Phase II Builder Area, Newport Coast, County of Orange, California, Project No. 1892112-06, dated June 12, 1996. , 1997a, Response to OCEMA Geotechnical Report Review Sheet dated June 28, 1996 Regarding Geotechnical Report of Rough Grading, Including Loffelstein Wall and Retaining Wall Construction, Tract 15091, Planning Area 1C-2, Newport Coast, County of Orange, California, Project No. 1892112-06, dated January 20, 1997. , 1997b, Response to OCEMA Geotechnical Report Review Sheet dated February 4, 1997 Regarding Response Report dated January 20, 1997, Tract 15091, Planning Area 1 C-2, Newport Coast, County of Orange, California, Project No. 1892112-06, dated March 18, 1997. 1997c, Geotechnical Report of Rough Grading, Tract 15091, Revision 3, Planning Area 1C-2, Phase II Builder Area, Newport Coast, County of Orange, California, Project No. 1892112-06, dated December 17, 1997. , 1998a, Response to OCEMA Geotechnical Report Review Sheet dated April 15, 1997 for Tract 15091, Planning Area 1C-2, Phase II Builder Area, Newport Coast, County of Orange, California, Project No. 1892112-06, dated January 16, 1998. , 1998b, Geoteclmical Review of Rough Grading Plan, Tract 15604, Planning Area 1C-2, Phase II Builder Area, Newport Coast, County of Orange, California, Project No. 1892112-12, dated February 3, 1998. , 1998c, Geotechnical Report of Rough Grading, Including Loffelstein Wall and Cantilever Retaining Wall Construction, Planning Area 1 C-2, Tract 15604 (Previously Designated Tract 15091), Pelican Crest, Newport Coast, County of Orange, California, dated November 12, 1998. , 1999, Response to County of Orange Geotechnical Report Review Sheet dated January 21, 1999 for Tract 15604 (Previously Designated Tract 15091), Pelican Crest, Phase II Builder Area, Newport Coast, County of Orange, California, Project No. 1892112-021, dated February 8, 1999. PETRA GEOTECHNICAL, INC. J.N. 248-05 LITERATURE REVIEWED ASSOCIATION OF ENGINEERING GEOLOGISTS, 1989, "Engineering Geology along Coastal Orange County": Association of Engineering Geologists. BARROWS, A.G., 1974, "A Review of the Geology and Earthquake History of the Newport -Inglewood Structural Zone, Southern California": California Division of Mines and Geology, Special Report 114. BLAKE, T.F., 1998, "UBCSEIS", A Computer Program for the Estimation of Uniform Building Code Coefficients Using 3-D Fault Sources." BRYANT, W., 1988, "Recently Active Traces of the Newport -Inglewood Fault Zone, Los Angeles and Orange Counties, California": California Division of Mines and Geology, Open -File Report 88-14. JOYNER, W.B., and FUMAL, T.E., 1985, "Predictive Mapping of Earthquake Ground Motion": in Ziony, J.I., (ed.), Evaluating Earthquake Hazards in the Los Angeles Region UBC An Earth -Science Perspective: U.S. Geological Survey Professional Paper 1360. MORTON, P.K., MILLER, R.V., and EVANS, J.R., 1976, "Environmental Geology of Orange County, California": California Division of Mines and Geology, Open File Report 79-8 LA. REAL, C.R., TOPPOZADA, T.R., PARKE, D.L., 1978, "Earthquake Epicenter Map of California": California Division of Mines and Geology, Map Sheet 39. TAN, S.S. AND EDGINGTON, W.J., 1976, "Geology and Engineering Geologic Aspects of the Laguna Beach Quadrangle, Orange County, California": California Division of Mines and Geology, Special Report 127. TOPPOZADA, T.R., BENNETT, J.H., BORCHARDT, G., SAUL, R., AND DAVIS, J.F., 1988, "Planning Scenario for a Major Earthquake on the Newport -Inglewood Fault Zone": California Division of Mines and Geology, Special Publication 99. VEDDER, J.G., YERKES, R.F., AND SCHOELLHAMER, J.E., 1957, "Geologic Map of the San Joaquin Hills -San Juan Capistrano Area, Orange County, California": United States Geological Survey, Open File Map 75-552. ZIONY, J.L, 1985, "Evaluating Earthquake Hazards in the Los Angeles Region - An Earth -Science Perspective": U.S. Geological Survey Professional Paper 1360, 505 p. PETRA GEOTECHNICAL, INC. J.N 248-05 APPENDIX A EXPLORATION LOGS k, PETRA Key to Soil and Bedrock Symbols and Terms PETRA ... .a i x t -_ f -Unified Soil.Classi ication-System ` ,� a' c h s 7 R $f CN y,. • `r., Fine-grained Soils Coarse -grained > 1/2 of materials is Soils smaller than #200 > 1/2 of materials is sieve Iaraerthan #200 sieve • The No. 200 U.S. Standard Sieve is about the smallest particle visible to the naked eye GRAVELS more than half of coarse traction is larger than #4 sieve Clean Gavels (less than 5% fines) GW Well -graded gravels, gravel -sand mixtures, little or no fines GP Poorly -graded gravels, gravel -sand mixtures, little or no fines Gravels with tines GM Silty Gravels, poorly -graded gravel -sand -silt mixtures GC Clayey Gravels, poorly -graded gravel -sand -clay mixtures SANDS more than half of coarse fraction is smaller than #4 sieve Clean Sands (less than 5% tines) SW Well -graded sands, gravelly sands, little or no tines SP Poorly -graded sands, gravelly sands, little or no tines Sands with tines SM Silty Sands, poorly -graded sand -gravel -silt mixtures SC Clayey Sands, poorly -graded sand -gravel -clay mixtures • SILTS & CLAYS Liquid Limit Less Than 50 NIL Inorganic silts & very tine sands, silty or clayey tine sands, clayey silts with slight plasticity CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays OL Organic silts & clays of low plasticity SILTS & CLAYS Liquid Limit Greater Than 50 mil Inorganic silts, micaceous or diatomaceous fine sand or silt CH Inorganic clays of high plasticity, fat clays OH Organic silts and clays of medium -to -high plasticity Highly Organic Solis PT Peat, humus swamp soils with high organic content $�;5rfraln{Size r-- Y�Y-nG$r441ji)tyd1'ilktf �';, -gk; k'#Y 1•i� � z ,.,...]x.tr F > .... r.r�'.k f.M ..: ,. i,-., a* 7 ;, , . , #sw :..,n ,'�1, t�'iq'A•>-9p' S 4^yr`y'X�2iiiif �..,;�%€xi',.o..fw� Fri .....,,. . ., _v?... s.. �," Description Sieve Size Grain Size Approximate Size Boulders >12" >12" Larger than basketball -sized Cobbles 3 - 12" 3 - 12" Fist -sized to basketball -sized Gravel coarse 3/4 - 3" 3/4 - 3" Thumb -sized to fist -sized fine #4 - 3/4" 0.19 - 0.75" Pea -sized to thumb -sized Sand coarse #10 - #4 0.079 - 0.19" Rock salt -sized to pea -sized medium #40 - #10 0.017 - 0.079" Sugar -sized to rock salt -sized fine #200 - #40 0.0029 - 0.017" Flour -sized to sugar -sized to Fines Passing #200 <0.0029" Flour -sized and smaller eLabaratory esAbb`'" revelations � 1 ,. ... F . ., .. 4 a.. *: �.v .- i t i< � ,fr.,e,.•... ., �. #� x� �,� fps i.�• i ;'2'�,k'�;,_2r;k S h 41.;., .. ., ..: i`[ MAX Maximum Dry Density MA Mechanical (Particle Size) Analysis EXP Expansion Potential AT Atterberg Limits SO4 Soluble Sulfate Content #200 #200 Screen Wash RES Resistivity DSU Direct Shear (Undisturbed Sample) pH Acidity DSR Direct Shear (Remolded Sample) CON Consolidation HYD Hydrometer Analysis SW Swell SE Sand Equivalent CL Chloride Content OC Organic Content RV R-Value COMP Mortar Cylinder Compression am rescrr SZ Approximate Depth of Seepage Approximate Depth of Standing Groundwater Modified California Split Spoon Sample Standard Penetration Test fi Bulk Sample I No Recovery in Sampler Shelby Tube Mad�f�ers ham`3`K... Trace < 1 Few 1 - 5% Some 5-12% Numerous 12 - 20 % Bedrock Hardnessk Soft Can be crushed and granulated by hand; "soil like" and structureless Moderately Hard Can be grooved with fingernails; gouged easily with butter knife; crumbles under light hammer blows Hard Cannot break by hand; can be grooved with a sharp knife; breaks with a moderate hammer blow Very Hard Sharp knife leaves scratch; chips with repeated hammer blows Notes: Blows Per Foot: Number of blows required to advance sampler 1 foot (unless a lesser distance is specified). Samplers in general were driven into the soil or bedrock at the bottom of the hole with a standard (140 lb.) hammer dropping a standard 30 inches unless noted otherwise in Log Notes. Drive samples collected in bucket auger borings may be obtained by dropping non-standard weight from variable heights. When a SPT sampler is used the blow count conforms td ASTM D-1536 EXPLORATION LOG Project: Proposed Single Family Residence Boring No.: B.,1 Location: 56 Shoreridge, Lot 45, Tract 15604, Newport Coast Elevation: 655 Job No.: 248-05 Client: Kamin Date: 4/8/05 Drill Method: Bucket Auger Driving Weight: 21501bs / 12 in Logged By: D. Hansen Depth (Feet) Lith- ology Material Description Samples Laboratory Tests W t e r Blows Per Foot oC r e B 1 k Moisture Content (%) Dry Density (pcf) Other Lab Tests — 5 — 10 — I / / ARTIFICIAL FILL (Af) to brown; moist; firm but desiccated stiff below; fine to medium grained bedrock fragments. � 24.2 26.1 9,3 24.0 22.8 25.8 97.8 2 9 1 115.4 84.0 81.9 86.6 Sandy Clay (CL): Olive brown 3 with roots in upper 12 inches, scattered hard siltstone sand; t 7 10 10/6" 8 IIE TERRACE DEPOSITS (Qt) IIE Clayey Sand (SC): Reddiish brown; moist; dense; fine to medium shell fragments. grained; layers with scattered IL = = BEDROCK - Monterey Formation (Tm) Siltstone: Olive to orange brown; moist; hard; thinly bedded; weathered. moderately fractured; moderately — 15 — 20 — L n D u :D 7 J = _ 11 Total Depth 21 Feet. No Caving. No Groundwater. PLATE A-1 Petra Geotechnical, Inc. EXPLORATION LOG Project: Proposed Single Family Residence 0 Boring No.: B-2 Location: 56 Shoreridge, Lot 45, Tract 15604, Newport Coast Elevation: 657 Job No.: 248-05 Client: Kamin Date: 4/8/05 Drill Method: Bucket Auger Driving Weight: 2150 lbs / 12 in Logged By: D. Hansen Depth (Feet) Lith- ology Material Description Samples Laboratory Tests W t e r Blows Per Foot oC r e B 1 k Moisture Content (%) Dry Density (pef) Other Lab Tests - — — — 5 10 — 15 — 20 —= r� ARTIFICIAL FILL (Af) reddish brown; moist; firm but desiccated stiff below; fine to medium grained bedrock fragments. brown; moist; dense; fine to medium 9.4 15.6 27.6 8.7 30.9 105.5 100.6 90.7 121.1 88.1 89.5 MAX EXP SO4 CHL pH RES Sandy Clay (CL): Brown to 6 with roots in upper 12 inches, sand; scattered hard siltstone Clayey Sand (SC): Reddiish grained. g / / / / Sandy Clay (CL): Olive brown; moist; stiff; scattered bedrock dense clayey sand. brown; moist; dense; fine to medium fragments, scattered layers of Clayey Sand (SC): Reddiish 6 5 4 19 grained. = _ BEDROCK - Monterey Formation (Tm) Siltstone: Olive to orange brown; moist; hard; thinly bedded; weathered. moderately fractured; moderately — 25 9 = _ 29.4 Total Depth 26 Feet. No Caving. No Groundwater. Z 0 0 Petra Geotechnical, Inc. PLATE A-2 APPENDIX B LABORATORY TEST PROCEDURES LABORATORY TEST DATA 1.Nk> PETRA LABORATORY TEST PROCEDURES Soil Classification Soils encountered within the property were classified and described utilizing the visual -manual procedures of the Unified Soil Classification System, and in general accordance with Test Method ASTM D 2488-00. The assigned group symbols are presented in the "Exploration Logs," Appendix A. In Situ Moisture and Density Moisture content and unit dry density of the in place earth materials were determined in representative strata. Test data are presented in the "Exploration Logs," Appendix A. Laboratory Maximum Dry Density The maximum dry density and optimum moisture content of the on -site fill materials were determined for a selected sample in accordance with Method A of ASTM D 1557-02. The results of this test are presented on Plate B-1. Expansion Potential An expansion index test was performed on a representative sample of the on -site fill materials in accordance with Uniform Building Code Standard 18-2. The test result is presented on Plate B-1. Chemical Analysis Chloride and soluble sulfate analyses were performed on a selected sample of fill material to determine its chemical contents. These tests were performed in accordance with Test Method Nos. California 417 and 422. The results of these tests are included on Plate B-1. Atterberg Limits The Atterberg limits (liquid limit, plastic limit and plasticity index) were determined for a representative sample of fill in accordance with Test Method ASTM D 4318. The results of this test are included on Plate B-1. pH and Minimum Resistivity The pH value and minimum resistivity of a representative sample of fill were performed in order to determine its corrosivity. These tests were performed in accordance with Test Method Nos. California 747 and 643. Test results are presented on Plate B-1. PETRA GEOTECHNICAL, INC. J.N. 248-05 LABORATORY MAXIMUM DRY DENSITY' Boring Number beptliP (£' 5 Soil Type ... .........:. F t► ig . Moisture (%).. Maunlit*b ...bensity (pc) B-2 1.0 - 3.0 A — Sandy Clay (CL) 12.0 121.0 EXPANSION INDEX TEST DATA' A — Sandy Clay (CL) 63 arisioi Potent'ig) Medium SOLUBLE SULFATES4 Soil Type = Sulfate Co110 ('' A - Sandy Clay (CL) 0.1081 CHLORIDES5 A — Sandy Clay (CL) pH AND MINIMUM RESISTNITY6 550 01 Type P14 Mlina uni esistipty (ohmzcm) A — Sand Clay (CL) 7.9 520 ATTERBERG LIMITS SoilfType e Liquid I emit Plash soh Timit I'lasticify Index A — Sandy Clay (CL) 48 23 25 (1) (2) (3) (4) (5) (6) (7) Per Test Method ASTM D 1557-02 Per Uniform Building Code Standard 18-2 Per UBC Table 18-I-B, "Classification of Expansive Soils" Per California Test Method No. 417 Per California Test Method No. 422 Per California Test Method Nos. 747 and 643 Per Test Method ASTM D 4318 PLATE B-1 PETRA GEOTECHNICAL, INC. J.N. 248-05 121 161 624 0 J c rn 0 FIREPLACE 8'-0" TRELLIS NEW WALL 3'-0" EXISTING WA (APPROX. 6') THIS PORTIO WALL STEPS 1 652 653--- - Do 654 --- VI -- 655 -- 656._ 657 -- • PiIiillPH■■ ■ T .ii.■�■_ (SWIMMING POOL NEW WALL PILASTER -------------- 6 18" ABOVE GRAD Lot 45 Tract 15604 TOP OF SLAB = 654.00' Lor".4 Z. miammirmiromirommismienpffia immorparompepppirimmtmer rag li Idpi_npillria SW iligloiimrimilmiMMINIERIONNIEmdiMpl ,,imigui somdigliiimmaiiiimilpiiiiTIVA III 1111111111 drill IMP IIIIIIIIIII III misommitaimmtaiimplimagiammon ,III IIEIihdillpiImilpiihmimniiisdapIIBNI MI FiNdialliilitaiipiiiirmliiiiiiiiiatiiiiilwilliiia 4,6,Mi_ 011111111191111191111111111r am 11*/- i"/ A.., „ / A ,e It - ROSE GA PA 622 -670.0v .F.243'30'00" --- -- ROSE GARDEN PA ozr Ass MEI 657 /1111 yor. Jim yi IIIII 1 up ;ph alkdWirikdbalskia Mountable curb PILASTER PILASTERS TYPICAL ALL 6 FRONT PILASTERS Site Nan Existing 20- to 30-foot-wide by 10-foot-deep Keyway • 116 7—EXISTING WALL (APPROX. 6 BOX POOL EQUIPT. AC UNITS (F) 24" iBQX PILASTER 28 1. REFER TO THE LANDSCAPE DRAWINGS FOR ADDITIONAL SITE INFORMATION. 2. PLANTING AREAS MUST BE A MINIMUM OF ONE FOOT LARGER THAN THE PROPOSED BOX SIZE. FOOTINGS AT TREE LOCATIONS MUST BE BOARD -FORMED AND L-SHAPED WALL FOOTINGS FOR THE PROPERTY UNE AND ANY RETAINING WALLS TO ASSURE THAT TREES AND PLANTS WILL FIT. 3. ALL GATES, WALLS, FENCES, AND PILASTERS OUTSIDE OF THE BUILDING ENVELOPE ARE RESTRICTED TO A MAXIMUM OF SIX FEET (6'-0") ABOVE EXISTING GRADE. 4. CONTRACTOR MAY NOT PLACE FILL SOIL OR EXCAVATE AT OR NEAR THE PROPERTY LINE. 5. FLARED DRIVEWAY EDGE IS NOT PERMITTED DUE TO THE ROLLED CURB CONDITION. 6. AU_ NEW PROPERTY UNE WALLS AND PILASTERS WILL BE CENTERED ON THE PROPERTY LINES. 7. THE MAILBOX IS TO BE LOCATED 18" FROM THE BACK OF CURB IN THE H.O.A. PARKWAY. 8. PLANIERS PROPOSED NEXT TO THE PROPERTY LINE MUST MAINTAIN A MINIMUM OF 42-0" CLEAR. 9. PLANTING SHALL NOT EXCEED 5' AND TREE CANOPIES SHALL BE MAINTAINED CLEAR OF THE 30 DEGREE VIEVi CONE. 10. REFER TO LANDSCAPE DRAYANGS FOR ALL TOP OF WALL AND FINISH GRADE/ SURFACE INFORMATION. 11. ONCE APPROVED, THESE DRAWINGS CONSTITUTE A CONTRACTUAL AGREEMENT BETWEEN OWNER AND THE SHADY CANYON HOMEOWNER ASSOCIATION. ANY CHANGES TO THE SPECIFICATIONS WITHIN THESE DRAWINGS MUST BE SUBMIi AND APPROVED BY THE DESIGN REVIEW COMMITTEE PRIOR TO ANY FORM OF WORK OR CONSTRUCTION. 12. WALL FOOTINGS AT TREE LOCATIONS MUST BE BOARD FORMED TO ELIMINATE BOIL OVER, AND ALL EXTRANEOUS CONCRETE MUST BE REMOVED ROM THE SITE. 13. BOTH SIDES OF THE PROPERTY LINE WALLS, FENCES, AND PILASTERS MUST BE COMPLETELY FINISHED AS REQUIRED BY THE DESIGN GUIDEUNES. 14. PROPERTY UNE WALLS MUST BE A MINIMUM OF 5'-0" AND A MAXIMUM OF 6.-0" ABOVE EXISTING GRADE, LES5 THE EROSION CONTROL BERM. PILASTERS MAY BE 6°-8" MAXIMUM. 15. BOX SIZES OF TREES ARE SHOM ON ALL SITE PLANS TO PREVENT CONCRETE FOOTINGS OR PIPING (DRAINAGE, UTILITY, IRRIGATION, OR WAIER FEATURE) FROM IMPEDING THE INSTALLATION OR GROWTH OF THE SPECIFIED TREES. ALL CONTRACTORS ARE REQUIRED TO RESPECT THE PROPOSED LOCATION OF ALL PLANT MATERIAL. 16. THE GRADE ADJACENT TO THE SIDE AND REAR PROPERTY LINES MUST REMAIN AT EXISTING GRADE FOR FOUR(4°) FEET CLEAR. General Notes 2 3 4 5 6 7 8 9 11 12 13 15 16 18 19 20 21 22 23 24 26 28 29 30 32 34 35 EXISTING DOMESTIC WATER METER/VALVE, REFER TO CIVIL DRAVANGS EXISTING MANHOLE COVER, REFER TO CIVIL DRAWINGS EXISTING UTIUTY BOX, REFER TO CIVIL DRAWINGS EXISTING ELECTRICAL BOX, REFER TO CIVIL DRAWINGS BACK OF EXISTING CONCRETE CURB AT PROPERTY LINE MAIL BOX (18" FROM BACK OF CURB), REFER TO LANDSCAPE DRAWINGS SITE WALL, REFER TO LANDSCAPE AND CIVIL DRAWINGS PILASTER AT SITE WALL, REFER TO LANDSCAPE AND CIVIL DRAWINGS BOLD DASHED LINE INDICATES SETBACK EXISTING CONTOURS SHOWN DOTTED SLOPE BANK - SHOMI SOLID HARDSCAPE, REFER TO LANDSCAPE DRAWINGS SOFTSCAPE, REFER TO LANDSCAPE DRAWINGS TURF, REFER TO LANDSCAPE DRAW1NGS PROPOSED LANDSCAPE TREES, REFER TO LANDSCAPE DRAWINGS POTTED PLANTING CONDENSER LOCATION, REFER TO LANDSCAPE DRAWINGS ELECTRIC METER LOCATION, REFER TO CIVIL AND LANDSCAPE DRAWINGS GAS METER LOCATION, REFER TO CIVIL AND LANDSCAPE DRAWINGS TELEPHONE AND CABLE TV BOXES BACKFLOW DEVICE SITE STAIRS, STONE, REFER TO LANDSCAPE AND CIVIL DRAWINGS STAINED WOOD GATES, REFER TO LANDSCAPE DRAWINGS. KOI POND, REFER TO LANDSCAPE DRAWINGS WOOD BRIDGE, REFER TO LANDSCAPE DRAWINGS SWIMMING POOL OR SPA POOL CABANA, REFER TO LANDSCAPE DRANANGS POOL EQUIPMENT, REFER TO LANDSCAPE DRAWINGS VINE -COVERED WROUGHT IRON ARBOR VINE -COVERED WROUGHT IRON TRELLIS BUILT-IN BARBECUE, REFER TO LANDSCAPE DRAVANGS, GRANITE COUNTER TOP STACKED STONE TREE SOIL RETAINING WALLS - PER LANDSCAPE DRAWNGS BUILT-IN CONCRETE SEATING, REFER TO LANDSCAPE DRAWINGS CARVED STONE FOUNTAIN, REFER TO LANDSCAPE DRAWINGS FF: FINISH FLOOR FS: FINISH SURFACE_ FG: FINISH GRADE PH: TOP OF WALL TP: TOP OF PILASTER TC: TOP OF CURB TF: TOP OF FENCE PA: PLANTING AREA Site Plan Keynotes and Abbreviations Af Cttm Tm EXPLANATION Artificial Fill Eerrace Deposits (Circled Where Buricd) Bedrock -Monterey Formation (Circled Where Buried) GEOLOGIC SYMBOLS 13-2 Ligif 643 Approximate Location of Exploratory Boring Approximate Elevation of Remedial Removal Bottom (Petra, 2005) Strike and Dip of Bedding Observed During Grading (Leighton, 1998) Approximate Elevation of Remedial Removal Bottom (Leighton, 1998) • • • • • Approximate Location of Buried Geologic Contact t PETRA GEOTECHNICAL, INC. J.N. 248-05 MAY, 2005 PLATE 1 B T A ARCHITECTS 2 EXECUTIVE CIRCLE 1<,,a m in CSIC Lot 45, Tract 15604 Pelican Crest II Newport Beach, Ca Paul and Jackie Kamin 400 Morning Star Lane Newport Beach, CA 92660 Site Plan Submittal #2 Not for Construction Project Number 04026 ACC Submittal #1 MAR. 15, 2005 ACC Submittal #2 Building Submittal -Plan Check No. Bid Issue Construct. Issue Revision Revision Revision Revision Sheet