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Home My WebLink AboutCDP 02-50; RUSSELL REMODEL; PRELIMINARY GEOTECHNICAL EVALUATION; 2003-02-10• retreat in the vicinity, the subject site is located in an area with a moderate shoreline risk and average erosion rate of 1 .2 inches to 9.1 inches per year. It is our understanding that a sea wall is proposed for the lower bluff at the subject site. Subsurface and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into .. final design and construction, and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along fill/bedrock contacts and along zones of contrasting permeabilities should not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. The groundwater conditions observed and opinions generated were those at the time of our investigation. Conditions may change with the introduction of irrigation, rainfall, or other factors that were not obvious at the time of our investigation. • Two alternatives for earthwork and foundation design have been developed, based on the site conditions. Alternative No. 1 consists of complete removal and recompaction of existing undocumented artificial fill and the construction of a conventional slab on grade foundation. Alternative No. 2 consists of minimal to no grading and the use of a pier and grade beam foundation system for structural support. It should be noted that Alternative No. 1 would require shoring and bracing for excavation adjacent to and below the existing foundation system. • The geotechnical design parameters provided herein should be considered during construction by the project structural engineer and/or architect. Karnak Architecture File:e:\wp7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC Page Two TABLE OF CONTENTS SCOPE OF SERVICES ................................................... 1 SITE DESCRIPTION AND PROPOSED DEVELOPMENT ......................... 1 ., FIELD STUDIES ......................................................... 3 REGIONAL GEOLOGY .................................................... 3 COASTAL BLUFF GEOMORPHOLOGY ...................................... 4 SITE GEOLOGIC UNITS .................................................. 4 Undocumented Artificial Fill .......................................... 4 Beach Deposits .................................................... 5 Terrace Deposits .................................................. 5 Santiago Formation ................................................ 5 GEOLOGIC STRUCTURE ................................................. 5 FAULTING AND REGIONAL SEISMICITY ..................................... 5 Faulting .......................................................... 5 SeIsmIcIty ........................................................ 7 Seismic Shaking Parameters ......................................... 8 SECONDARY SEISMIC HAZARDS .......................................... 8 GROUNDWATER ........................................................ 8 LONG TERM SEA-LEVEL CHANGE ......................................... 9 SHORT TERM SEA LEVEL CHANGE ........................................ 9 COASTAL-BLUFF RETREAT .............................................. 10 Marine Erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0 Mechanical and Biological Processes ........................... 1 O Water Depth, Wave Height, and Platform Slope ................... 11 ------------·------· --Marine Erosion at the Cliff-Platform Junction ...................... ii Subaerial Erosion ................................................. 11 Groundwater ............................................... 11 Slope Decline .............................................. 11 LABORATORY TESTING ................................................. 12 Classification ..................................................... 12 Moisture-Density Relations ......................................... 12 Laboratory Standard-Maximum Dry Density ............................ 12 GeoSoils, Ine. Expansion Index Testing ........................................... 12 Direct Shear Tests ................................................ 13 Soluble Sulfates/pH Resistivity ...................................... 13 SLOPE STABILITY ...................................................... 13 SLOPE STABILITY ANALYSES ............................................ 14 Gross Stability Analysis ............................................ 14 Surficial Slope Stability ............................................. 14 DISCUSSION AND CONCLUSIONS ........................................ 14 General ......................................................... 14 Earth Materials ................................................... 15 Undocumented Artificial Fill ................................... 15 Subsurface and Surface Water ...................................... 15 Slope Stability .................................................... 15 Earthwork and Foundation Design ................................... 15 RECOMMENDATIONS-EARTHWORK CONSTRUCTION ....................... 16 Grading ......................................................... 16 General ................................................... 16 Site Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Removals (Unsuitable Materials) ............................... 17 Fill Placement .............................................. 17 FOUNDATION RECOMMENDATIONS ...................................... 17 General ......................................................... 17 CONVENTIONAL SLAB ON GRADE FOUNDATIONS .......................... -18 Design .......................................................... 18 Bearing Value .............................................. 18 Lateral Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Foundation Settlement -Structural Loads ........................ 18 Construction ..................................................... 19 Setbacks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 CONVENTIONAL CONCRETE SLABS ON GRADE ............................ 20 Conventional Floor Slabs ........................................... 20 Exterior Flatwork : ................................................. 20 DRILLED PIER AND GRADE BEAM FOUNDATIONS ........................... 21 SHORING AND BRACING ................................................ 22 CORROSION AND CONCRETE TESTS ..................................... 23 Karnak Architecture File:e:\wp7\35D0\3512a.pge GeoSoils, Ine. Table of Contents Page ii UTILITIES ............................................................. 23 ADDITIONAL RECOMMENDATIONS/DEVELOPMENT CRITERIA ................ 23 Landscape Maintenance and Planting ................................ 23 Site Improvements ................................................ 24 Drainage ........................................................ 24 . Footing Excavations ............................................... 24 Trenching ....................................................... 25 Utility Trench Backfill .............................................. 25 Grading Guidelines ................................................ 25 PLAN REVIEW ......................................................... 25 LIMITATIONS .......................................................... 26 FIGURES: Figure 1 -Site Location Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Figure 2 -Earthquake Epicenter Map .................................. 6 ATTACHMENTS: Appendix A-References ................................... Rear of Text Appendix B -Report of Preliminary Geotechnical Investigation by GEIRear of Text Appendix C -Boring Logs .................................. Rear of Text Appendix D -Slope Stability Analysis ......................... Rear of Text Appendix E -Grading Guidelines ............................ Rear of Text Appendix F -Homeowner's Maintenance Guidelines . . . . . . . . . . . . . Rear of Text Plate 1 -Geotechnical Map ......................... Rear of Text in Folder Plate 2 -Geologic Cross-Section X-X' ................. Rear of Text in Folder Karnak Architecture File:e:\wp7\3500\3512a.pge GeoSoils, lne. Table of Contents Page iii PRELIMINARY GEOTECHNICAL EVALUATION PROPOSED ADDITION, 2641-43 OCEAN STREET CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA SCOPE OF SERVICES The scope of our services has included the following: 1. Review of readily available published literature and maps of the vicinity, including review of a preliminary geotechnical report prepared by Geotechnical Exploration, Inc. for the adjacent residence to the south (Appendix A). 2. Geologic mapping of exposed conditions, including sea cliff bedding and joinVfracture attitudes. 3. Subsurface exploration consisting of the excavation of one exploratory hand auger boring to determine the soil/bedrock profiles, obtain relatively undisturbed and bulk samples of representative materials, and delineate earth material parameters that may affect the stability of the existing bluff and the proposed development. 4. Laboratory testing of representative soil samples collected during our subsurface exploration program. 5. Evaluation of potential areal seismicity and secondary seismic hazards. 6. Slope stability analyses. 7. Appropriate engineering and geologic analyses of data collected, and preparation of this report and accompaniments SITE DESCRIPTION AND PROPOSED DEVELOPMENT The study area is a coastal bluff located above the beach in Carlsbad, California (see Site Location Map, Figure 1). A single-family, three-story, wood-frame residence exists on a rectangular-shaped parcel that fronts on the beach. Access to the beach below the bluff on the site is via private stairs on the property. Slope gradient of the lower, approximately 8-foot high bluff is approximately 50 to 60 degrees. The lower bluff face is covered with dense landscape, and the lower 2 feet of the bluff is protected with rip-rap. No seepage was observed in the bluff face. The existing residence is terraced into the remaining approximately 50-foot high cliff. GeoSoils, lne. Based on conversations with the client, proposed development on the site will consist of an addition in the area of the open courtyard (see Plate 1). It is anticipated that the planned structure is proposed to use continuous footings and slab-on-grade, with wood-frame and/or masonry block construction. Building loads are assumed to be typical for this type of relatively light construction. BACKGROUND GSI has performed a review of a preliminary geotechincal investigation performed by Geotechnical Exploration, Inc. (GEi, 2002) for the adjoining property to the south of the subject site. The GEi report has been approved by the City of Carlsbad. Based upon the proximity of the adjacent site (within 50 feet), it is GSl's opinion that it is reasonable to assume that geological conditions are the same or similar to geological conditions at the subject site. Thus, GSI is relying on findings presented in the GEi report, and has also utilized GEi's subsurface information and laboratory data in our preliminary geotechnical report for the subject site. A copy of the GEi report is provided in Appendix B. FIELD STUDIES Site specific field studies conducted by GSI consisted of geologic mapping of the existing geologic conditions in the bluff, and the drilling of one exploratory hand auger boring for evaluation of near-surface soil and geologic conditions. The boring was logged by a geologist from our firm who collected representative bulk and undisturbed samples from the boring for appropriate laboratory testing. The log of the boring is presented in Appendix C. The location of the boring is presented on Plate 1. REGIONAL GEOLOGY The site is located in Peninsular Ranges geomorph ic province of California. The Peninsular Ranges are characterized by northwest-trending, steep, elongated ranges and valleys. The Peninsular Ranges extend north to the base of the San Gabriel Mountains and south into Mexico to Baja California. The province is bounded by the east-west trending Transverse Ranges geomorphic province to the north and northeast, by the Colorado Desert geomorphic province to the southeast, and by the Continental Borderlands geomorphic province to the west. In the Peninsular Ranges, sedimentary and volcanic units ----------------diseontfnuously mantle the crystalline bedrock, alluvial deposits have filled in the lower valley areas, and young marine sediments are currently being deposited/eroded in the coastal and beach areas. Karnak Architecture 2641-43 Ocean Street File:e:\wp 7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 1 o, 2003 Page3 COASTAL BLUFF GEOMORPHOLOGY The coastal-bluff profile at the subject site may be divided into three zones: the shore platform, a lower bluff slope generally ranging in inclination between 50 to 60 degrees, and an upper near-vertical cliff surface termed the sea cliff. This bluff profile is generally indicative of an inactive erosional sea cliff stage (Emery and Kuhn, 1982). The bluff top is ., the boundary between the upper bluff and coastal terrace. Offshore from the sea cliff is an area of indefinite extent, termed the near-shore zone. The bedrock surface in the near-shore zone, which extends out to sea from the base of the sea cliff, is the shore platform. As pointed out by Trenhaile (1987), worldwide, the shore platform may vary in inclination from near horizontal to as steep as 3: 1 (horizontal to vertical). The boundary between the lower bluff and the shore platform is the bluff-platform junction, or sometimes called the shoreline angle. Within the near-shore zone is a subdivision called the inshore zone, beginning where the waves begin to break. This boundary varies with time because the point at which waves begin to break changes dramatically with changes in wave size and tidal level. During low tides, large waves will begin to break further away from shore. During high tides, waves may not break at all or they may break directly on the lower cliff. Closer to shore is the foreshore zone, that portion of the shore lying between the upper limit of wave wash at high tide and the ordinary low water mark. Both of these boundaries often lie on a sand or cobble beach. In this case of a shoreline with a bluff, the foreshore zone extends from low water to the lower face of the bluff. SITE GEOLOGIC UNITS Three earth materials units were observed and/or encountered in the vicinity of the subject site. A general description of each material type is presented as follows, from youngest to oldest. Undocumented Artificial Fill Undocumented artificial fill was encountered to an approximate depth of 6 feet in the vicinity of the open courtyard. This material was moist to wet, loose to medium dense, silty sand, and may settle appreciably under additional fill, foundation, or improvement loadings. Recommendations for the treatment of the undocumented artificial fill are presented in the -------······ • --earthwork section of this report. Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 1 O, 2003 Page4 Beach Deposits Beach deposits, located along the base of the bluff, are composed of recent unconsolidated sands. These materials are actively being deposited and may vary in amount and distribution over time. Terrace Deposits Our field review of a geotechnical report for adjacent property to the south, and literature review indicate that the upper sea bluff is composed primarily of Pleistocene-age terrace deposits consisting of relatively sandy sediments, weakly cemented with iron oxide, that rest upon a yet older wave-cut terrace, also Pleistocene in age. The terrace deposits make up the sea bluff primarily between approximately 12 feet Mean Sea Level (MSL) to near the top of the bluff. The existing residence has been terraced into this material. Santiago Formation The Eocene-age Santiago Formation underlies the terrace deposits on the site. These materials were observed in the lower portions of the coastal bluff. Onsite, this formation consists of silty, fine-grained sandstone. The materials were moderately cemented and micaceous. GEOLOGIC STRUCTURE The terrace deposits are generally massively to thickly-bedded, and are relatively flat lying. The Santiago Formation is mapped in the vicinity with a gentle incline (dipping approximately 5 to 1 O degrees) in a northeasterly direction (Weber, 1982). FAULTING AND REGIONAL SEISMICITY Faulting The site is situated in an area of active as well as potentially-active faults. Our review indicates that there are no known active faults crossing the site (Weber, 1982), and the site is not within an Earthquake Fault Zone (Hart and Bryant, 1997). There are a number of faults in the southern California area that are considered to be active --• ----and would have an earthquake effect on the site in the form of ground shaking, should they be the source of an earthquake. These include-but are not limited to-the San Andreas fault, the San Jacinto fault, the Elsinore fault, the Coronado Bank fault zone, and the Newport- Inglewood-Rose Canyon fault zone. The location of these and other major faults relative to the site are indicated on the Earthquake Epicenter Map, Figure 2. The possibility of ground acceleration or shaking at the site may be considered as approximately similar to the southern California region as a whole. Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, Ine. W.O. 3512-A-SC February 10, 2003 Pages The following table lists the major faults and fault zones in southern California that could have a significant effect on the site should they experience significant activity. ABBREVIATED APPROXIMATE DISTANCE FAULT NAME MILES (KM} Coronado Bank-Agua Blanca 21 (33) Elsinore 25(40) Newport-lngelwood-Offshore 5(8) Rose Canyon 5(8) Seismicity The acceleration-attenuation relations of Idriss (1994) and Campbell and Bozorgnia (1997), Horizontal-Random have been incorporated into EQFAULT (Blake, 1989). For this study, peak horizontal ground accelerations anticipated at the site were determined based on the random mean plus 1 -sigma attenuation curve and mean attenuation curve developed by Joyner and Boore (1982), Sadigh et al. (1987), and Campbell and Bozorgnia (1994). EQFAULTisacomputerprogram byThomasF. Blake {1989), which performs deterministic seismic hazard analyses using up to 150 digitized California faults as earthquake sources. The program estimates the closest distance between each fault and a given site. If a fault is found to be within a user-selected radius, the program estimates peak horizontal ground acceleration that may occur at the site from an upper bound ("maximum credible") earthquake on that fault. Site acceleration (g) is computed by any of at least 30 user- selected acceleration-attenuation relations that are contained in EQFAULT. Based on the EQFAULTprogram, peak horizontal ground accelerations from an upper bound event atthe site may be on the order of 0.67g to 0.72g. Historical site seismicity was evaluated with the acceleration-attenuation relations of Campbell (1997) and the computer program EQSEARCH (Blake, 2000). This program was utilized to perform a search of historical earthquake records for magnitude 5.0 to 9.0 seismic events within a 100-mile radius, between the years 1800 to 2001. Based on the selected acceleration-attenuation relation, a peak horizontal ground acceleration has been estimated, which may have affected the site during the specific seismic events in the --------.. -. -past-Based on the available data and attenuation relationship used, the estimated maximum (peak) site acceleration during the period 1800 to 2001 was 0.309 g. Karnak Architecture 2641-43 Ocean Street File:e:\wp 7\3500\3512a.pge GeoSoils, Ine. W.O. 3512-A-SC February 10, 2003 Page? Seismic Shaking Parameters Based on the site conditions, Chapter 16 of the Uniform Building Code (International Conference of Building Officials, 1997), the following seismic parameters are provided: I UBC TABLE/FIGURE DESIGNATION I FAULT PARAMETERS I Seismic zone (per Figure 16-2*) 4 Seismic zone factor Z (per Table 16-1*) 0.40 Soil Profile Types (per Table 16-J*) So Seismic Coefficient Ca (per Table 16-Q*) 0.44 Na Seismic Coefficient Cv (per Table 16-R*) 0.64 NV Near Source factor Na (per Table 16-S*) 1.00 Near Source factor Nv (per Table 16-T*) 1.10 Distance to Seismic Source 4.8 mi. (7.7 km) Seismic Source Type (per Table 16-U*) B Upper Bound Earthquake M,,.,6.9 * Figure and table references from Chapter 16 of the Uniform Building Code (1997). SECONDARY SEISMIC HAZARDS Potential secondary seismic related hazards such as ground rupture due to faulting, liquefaction, dynamic settlement, seiche and tsunami, are often associated with a seismic event. Since no active faults are known to cross the site, the potential for ground rupture is considered low. Based on review of available data, the potential for liquefaction to affect the site appears to be low. The potential for dynamic settlement to affect the site appears to be low to moderate. Due to the elevation of the residential structural in regard to the ocean elevation, the potential for seiche or tsunami to affect that area is considered low. However, significant tidal waves generated from a seismic event could affect the lower portion of the site and affect overall bluff stability, possibly even affecting the existing proposed structures. GROUNDWATER Groundwater was not observed seeping from the bluff slope nor in exploratory borings performed by Geotechnical Exploration, Inc. (2002). However, this does not preclude the Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 1 o, 2003 Pages possibility localized perched groundwater, seepage may occur locally ( due to heavy precipitation or irrigation) in areas where natural or fill soils overlie less permeable materials or soils. Such conditions may exist on the subject site at depth. Groundwater and surface water are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction, and that prudent surface and subsurface drainage practices are incorporated . into the construction plans. LONG TERM SEA-LEVEL CHANGE long-term (geologic) sea-level change is likely the major factor determining coastal evolution. Three general sea-level conditions are recognized: rising, falling and stationary. The rising and falling stages result in massive sediment release and transport, while the stationary stage allows time for adjustment and reorg~nization towards equilibrium. Major changes in sea level for the Quaternary period were caused by worldwide climate fluctuation resulting in at least 17 glacial and interglacial stages in the last 800,000 years and many before then. Worldwide sea-level rise associated with the melting of glaciers is commonly referred to as "glacio-eustatic" or "true" sea-level rise. During the past 200,000 years, eustatic sea level has ranged from more than 350± feet below the present to possibly as high as about 31 ± feet above. Sea-level changes during the last 18,000 years have resulted in an approximately 400-foot rise in sea level when relatively cold global climates of the Wisconsin ice age started to become warmer, melting a substantial portion of the continental ice caps. Sea-level data show a relatively rapid rise of about 1 meter per century from about 18,000 years before present to about 8,000 years ago. About 8,000 years ago, the rate of sea-level rise slowed, ultimately to a relatively constant rate of about 1 0 centimeters per century since about 6,000 years ago (Inman, 1976). More importantly, the world coastline, including that of California and the subject site, has been shaped largely within this 6,000-year period, with the sea at or within about 16 feet of its present level. SHORT TERM SEA LEVEL CHANGE There is no credible evidence that unfounded speculation of a significant "acceleration" in sea level rise will occur (Gerhard, et al, 2001; Harff, et al, 2001; Shinn, 2001; and Emery and Aubrey, 1991). In fact, the coastline has been affected more by the rate of adjustment --• --------to eustatic response to the removal of the ice sheets than by changes in sea level, within the past 6,000 years (Jenkins, 2001). Current data indicate a trend" ... no greater in rate or magnitude, and probably less in both, than changes that have occurred in the recent geologic past (Blumle, et al, 2000)." The planet is now in a period of gradual cooling from the time of the post-glacial thermal optimum 6,000-9,000 years ago. Global temperatures are now on an irregular downward path, comparable to the Eemian interglacial, although Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, Ine. W.O. 3512-A-SC February 1 o, 2003 Page9 at present, we are experiencing a minor temperature increase as a partial recovery from the "Little Ice Age," which ended 150 years ago (Jenkins, 2000). COASTAL-BLUFF RETREAT Most of San Diego County's coastline has experienced a measurable amount of erosion in the last 20 to 30 years, with more rapid erosion occurring during periods of heavy storm surf (Kuhn and Shepard, 1984). The entire base of the sea cliff portion of the coastal bluff is exposed to direct wave attack along most of the coast. The waves erode the sea cliff by impact on small joints/fractures and fissures in the otherwise essentially massive bedrock units, and by water-hammer effects. The upper bluffs, which often support little or no vegetation, are subject to wave spray and splash, sometimes causing saturation of the outer layer and subsequent sloughing of over-steepened slopes. Wind, rain, irrigation, and uncontrolled surface runoff contribute to the erosion of the upper coastal bluff, especially on the more exposed over-steepened portions of the friable sands. Where these processes are active, unraveling of cohesion less sands has resulted along portions of the upper bluffs. The subject site is located in an area with a moderate shoreline risk based upon reported unfavorable geology, inadequate setback, and a narrow beach by California Department of Boating and Waterways and San Diego Association of Governments ([CDBW and SDAG], 1994). Moore, et. al, (1999), studied the coastal cliffs of San Diego County and indicated that for the Carlsbad State Beach area (located to the south of the subject property), the landward edge of the cliff top showed average erosion rates from 3 to 23 centimeters per year (1 .2 inches to 9.1 inches) between 1932 and 1994. Marine Erosion The factors contributing to "Marine Erosion" processes are described below. Mechanical and Biological Processes Mechanical erosion processes at the cliff-platform junction include water abrasion, rock abrasion, cavitation, water hammer, air compression in joints/fractures, breaking-wave shock, and alternation of hydrostatic pressure with the waves and tides. All of these processes are active in backwearing. Downwearing processes include all but breaking- --------------wave--shock---(Trenhaile, 1987). Backwearing and downwearing by the mechanical processes described above are both augmented by bioerosion, the removal of rock by the direct action of organisms (Trenhaile, 1987). Backwearing at the site is assisted by algae in the intertidal and splash zones and by rock-boring mollusks in the tidal range. Algae and associated small organisms bore into rock up to several millimeters. Mollusks may bore several centimeters into the rock. Chemical and salt weathering also contribute to the erosion process. Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, Inc. W.O. 3512-A-SC February 10, 2003 Page 10 Water Depth, Wave Height, and Platform Slope The key factors affecting the marine erosion component of bluff-retreat are water depth at the base of the cliff, breaking wave height, and the slope of the shore platform. Along the entire coastline, the sea cliff is subject to periodic attack by breaking and broken waves, which create the dynamic effects of turbulent water and the compression of entrapped air ., pockets. When acting upon jointed and fractured rock, the "water-hammer" effect tends to cause hydraulic fracturing which exacerbates sea cliff erosion. Erosion associated with breaking waves is most active when water depths at the cliff-platform junction coincide with the respective critical incoming wave height, such that the water depth is approximately equal to 1.3 times the wave height. Marine Erosion at the Cliff-Platform Junction The cliff-platform junction contribution to retreat of the overall sea cliff is from marine erosion, which includes mechanical, chemical, and biological erosion processes. Marine erosion, which operates horizontally (backwearing) on the cliff as far up as the top of the splash zone, and vertically (downwearing) on the shore platform (Emery and Kuhn, 1980; Trenhaile, 1987). Backwearing and downwearing typically progress at rates that will maintain the existing gradient of the shore platform. Subaerial Erosion "Subaerial Erosion" processes are discussed as follows. Groundwater The primary erosive effect of groundwater seepage upon the formation at the site is spring sapping, orthe mechanical erosion of sand grains by water exiting the bluff face. Chemical solution, however, is also a significant contributor (especially of carbonate matrix material). As indicated previously, as groundwater approaches the bluff, it infiltrates near-surface, stress-relief, bluff-parallel joints/fractures, which form naturally behind and parallel to the bluff face. Hydrostatic loading of bluff parallel (and sub-parallel) joints/fractures is an important cause of block-toppling on steep-cliffed lower bluffs (Kuhn and Shepard, 1980). Slope Decline The process of slope decline consists of a series of steps, which ultimately cause the bluff to retreat: The base of the bluff is first weakened by wave attack and the development of wave cut niches and/or sea caves, and bluff parallel tension joint/fractures. As the weakened sea cliff fails by blockfall or rockfall, an over-steepened bluff face is left, with the debris at the toe of the sea cliff. Ultimately, the rockfal I/blockfall debris is removed by wave action, and the marginal support for the upper bluff is thereby removed. Progressive surficial slumping and failure of the bluff will occur until a condition approaching the angle Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 1 o, 2003 Page 11 of repose is established over time, and the process begins anew. Bluffs with slope angles in the 35 to 40 degrees range may indicate ages in the 75-to 100-year range. Steeper slopes indicate a younger age. Slopes at the site vicinity indicate a relatively older age, which are generally typical of inactive erosion. LABORATORY TESTING Laboratory tests were performed on representative samples of representative site earth materials in order to evaluate their physical characteristics. Test procedures used and results obtained are presented below. Classification Soils were classified visually according to the Unified Soils Classification System. The soil classification of onsite soils is provided in the exploration log in Appendix C. Moisture-Density Relations The maximum density and optimum moisture content was determined for the major soil type encountered in the boring. The laboratory standard used was ASTM D-1557. Results of this testing are presented on the boring log in Appendix C. Laboratory Standard-Maximum Dry Density To determine the compaction character of a representative sample of onsite soil, laboratory testing was performed in accordance with ASTM test method D-1557. Test results are presented in the following table: LOCATION MAXIMUM DENSITY (pcf) OPTIMUM MOISTURE CONTENT (%) B-1@ 0-6 132.0 9.0 Expansion Index Testing Expansion index testing was performed on a representative soil sample, according to USC ___________ Standard_18-2 of the Uniform Building Code (1997). The test result is presented below: LOCATION B-1 @0-6' Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge SOIL TYPE Sand EXPANSION INDEX 0 GeoSoils, lne. EXPANSION POTENTIAL Very Low W.O. 3512-A-SC February 10, 2003 Page 12 Direct Shear Tests Remolded shear testing was performed on an undisturbed sample in general accordance with ASTM test method D-3080. Test results are presented on the following table. LOCATION COHESION (psf} INTERNAL FRICTION (Degrees) 8-1 @2' (fill) 105 32 Soluble Sulfates/pH Resistivity One sample of the site materials in the artificial fill was analyzed for soluble sulfate content and corrosion to ferrous metals. The results are as follows: LOCATION SOLUBLE SULFATES (mg/kg) pH RESISTIVITY-SATURATED (ohms-cm) Artificial Fill 56 5.4 2,900 Site soils have a negligible potential to concrete (i.e., 0.0056 soluble sulfate percent by weight in soil). Per code, 4,000 psi concrete is required .. In addition, pH and resistivity tests were performed, which indicate site soils are acidic and are moderately corrosive to ferrous metals. Moderately corrosive soils are considered to range from 2,000 to 10,000 ohms-cm. In light of the salt environment of the site, the designer should consider the use of Type V concrete. SLOPE STABILITY The site and immediate vicinity is generally characterized by subaerial erosion and urbanization erosion. No geomorphic evidence for immediate gross slope instability was observed onsite, nor on the adjacent properties. However, this does not preclude the presence of conditions (structure, soil strength, etc.) contributing to a reduced gross stability. The slope faces, if left untreated, will likely continue to progressively erode and/or slump _______________ and. may accelerate during strong seismic shaking, severe winter storms or other similar events. Accordingly, there is some potential that natural slopes may be subject to instability during seismic shaking, heavy precipitation or strong storms, as would other similar existing slopes in the coastal southern California area. Mitigation would likely be necessary for all structures, including patios, spas, flatwork, etc., from being impacted. Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, Ine. W.O. 3512-A-SC February 10, 2003 Page 13 SLOPE STABILITY ANALYSES Analyses were performed utilizing the two-dimensional slope stability computer program "XSTABL." The program calculates the factor of safety for specified circles or searches for a circular, block, or irregular slip surface having the minimum factor of safety using the Jan bu, or general limit equilibrium (Spencer). A computer print-out of calculations and ., shear strength parameters used are provided in Appendix D. A representative cross section was prepared for analysis, utilizing data from our investigation and the map that depicts the existing slope. Thi.s cross section is provided as Plate 2. The location of the cross-section is shown on Plate 1. Gross Stability Analysis Based on the available data, the constraints outlined above, and our stability calculations of the most critical slopes shown in Appendix D, calculated factors-of-safety greater than code have been obtained for the existing slope on the subject site. This assumes that the slope remains in its current condition as depicted on the cross section shown on Plate 2 (i.e., no erosion, undermining, etc.). Surficial Slope Stability The surficial stability of the slope has been analyzed utilizing the shear strength parameters in Appendix D. Calculations are shown in Appendix D, which indicate a static surficial safety factor greater than code for the existing slopes. DISCUSSION AND CONCLUSIONS General Based on our field exploration, laboratory testing and geotechnical engineering analysis, it is our opinion that the subject site appears suitable for the proposed residential development from a geotechnical engineering and geologic viewpoint, provided that the recommendations presented in the following sections are incorporated into the design and construction phases of site development. The primary geotechnical concerns with respect to the proposed development are: • Depth to competent bearing material. • Slope stability. • Earthwork and design. • Potential for perched water. • Potential for corrosion. Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 1 o, 2003 Page 14 Earth Materials Undocumented Artificial Fill These earth materials are typically loose and are considered potentially compressible in their existing state; thus, the undocumented artificial fill on site may settle appreciably under , additional fill, foundation, or improvement loadings, and is not recommended for the support of new structures. Recommendations for the treatment of the artificial fill are presented in the earthwork section of this report. Subsurface and Surface Water Subsurface and surface water, as discussed previously, are not anticipated to affect site development, provided that the recommendations contained in this report are incorporated into final design and construction, and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along fill/bedrock contacts and along zones of contrasting permeabilities should not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. The groundwater conditions observed and opinions generated were those at the time of our investigation. Conditions may change with the introduction of irrigation, rainfall, or other factors that were not obvious at the time of our investigation. Slope Stability Surficial and gross stability analyses indicate generally stable conditions for the existing slope; however, based on a review of available published literature on coastal bluff retreat in the vicinity, the subject site is located in an area with a moderate shoreline risk and average erosion rate of 1.2 inches to 9.1 inches per year. It is our understanding that a sea wall is proposed at the toe of the existing slope. Earthwork and Foundation Design Two alternatives for earthwork and foundation design have been developed, based on the site conditions. Alternative No. 1 consists of complete removal and recompaction of --· ---·-· -•·-existing undocumented artificial fill and the construction of a conventional slab on grade foundation. Alternative No. 2 consists of minimal to no grading and the use of a pier and grade beam foundation system for structural support. It should be noted that Alternative No. 1 would require shoring and bracing for excavation adjacent to and below the existing foundation system. Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 10, 2003 Page 15 The recommendations presented herein consider these as well as other aspects of the site. In the event that any significant changes are made to proposed site development, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and the recommendations of this report verified or modified in writing by this office. Foundation design parameters are considered preliminary until the foundation design, layout, and structural loads are provided to this office for review. RECOMMENDATIONS-EARTHWORK CONSTRUCTION Grading General The following earthwork recommendations are to be implemented if the removal and recompaction of existing fill is to be performed in lieu of piers and grade beams. All grading should conform to the guidelines presented in Appendix Chapter A33 of the Uniform Building Code, the requirements of the City of Carlsbad, and the Grading Guidelines presented in this report as Appendix E, except where specifically superseded in the text of this report. Prior to grading, a GSI representative should be present at the preconstruction meeting to provide additional grading guidelines, if needed, and review the earthwork schedule. During earthwork construction all site preparation and the general grading procedures of the contractor should be observed and the fill selectively tested by a representative(s) of GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed by this office and if warranted, modified and/or additional recommendations will be offered. All applicable requirements of local and national construction and general industry safety orders, the Occupational Safety and Health Act, and the Construction Safety Act should be met. Site Preparation Debris, vegetation and other deleterious material should be removed from the improvement(s) area prior to the start of construction. Following removals, areas approved to receive additional fill should first be scarified and - -----------moisture -conditioned (at or above the soils optimum moisture content) to a depth of 12 inches and compacted to a minimum 90 percent relative compaction. This excludes the pavement areas, which should be compacted to 95 percent. Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, Inc. W.O. 3512-A-SC February 1 o, 2003 Page 16 Removals (Unsuitable Materials) The artificial fill should be removed and recompacted or reprocessed in areas proposed for settlement-sensitive improvements. Removal depths are estimated to range from 3 to 6 feet below proposed grade. Materials generated during removal operations may be re- used as compacted fill provided the materials are suitably moisture conditioned prior to . placement. When removals are completed, the exposed surface should be scarified, moisture conditioned and recompacted per the GSI grading guidelines (Appendix E) and recommendations herein. Fill Placement Subsequent to ground preparation, onsite soils may be placed in thin (±6-inch) lifts, cleaned of vegetation and debris, brought to a least optimum moisture content, and compacted to achieve a minimum relative compaction of 90 percent of the laboratory standard. If fill materials are imported to the site, the proposed import fill should be submitted to GSI, so laboratory testing can be performed to verify that the intended import material is compatible with onsite material. At least three business days of lead time should be allowed by builders or contractors for proposed import submittals. This lead time will allow for particle size ·analysis, specific gravity, relative compaction, expansion testing and blended import/native characteristics as deemed necessary. FOUNDATION RECOMMENDATIONS General In the event that the information concerning the proposed development plan is not correct, or any changes in the design, location or loading conditions of the proposed structure are made, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. The information and recommendations presented in this section are not meant to supersede design by the project structural engineer or civil engineer specializing in structural design. Upon request, GSI could provide additional consultation regarding soil ----------· --parameters-,-as-related to foundation design. Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 1 o, 2003 Page 17 CONVENTIONAL SLAB ON GRADE FOUNDATIONS Design Our field work and laboratory testing indicates that onsite soils are generally very low in expansion potential. Preliminary recommendations for foundation design and construction . are presented below based on the assumption that low expansive materials will be used for support of structures. The foundation system should be designed and constructed in accordance with the guidelines contained in the Uniform Building Code. Final foundation designs should be based upon conditions exposed following earthwork construction. Should higher expansive materials occur at pad grade, revised foundation recommendations would need to be provided by GSI. Conventional spread and continuous strip footings may be used to support the proposed structure, provided they are founded entirely in properly compacted fill or suitable terrace deposits. Bearing Value An allowable bearing value of 1,500 pounds per square foot should be used for design of continuous footings 12 inches wide and 12 inches deep and for design of isolated pad footings 24 inches square and 12 inches deep, entirely into compacted fill or terrace deposits. This value may be increased by 20 percent for each additional 12 inches in depth to a maximum value of 2,000 pounds per square foot. The above values may be increased by one-third when considering short duration seismic or wind loads. No increase, in bearing, for footing width is recommended. Residential footings should not simultaneously bear directly on suitable native and fill soils. Lateral Pressure Passive earth pressure may be computed as an equivalent fluid having a density of 250 pounds per cubic foot per foot of depth, to a maximum earth pressure of 2,500 pounds per square foot. An allowable coefficient of friction between earth material (fill) and concrete of 0.30 may be used with the dead load forces. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. Foundation Settlement -Structural Loads Provided that the recommendations contained in this report are incorporated into final design and construction phase of development, a majority (>50 percent) of the anticipated foundation settlement is expected to occur during construction. Maximum settlement is not expected to exceed approximately ½ inch and should occur below the heaviest loaded columns. Differential settlement is not anticipated to exceed ¼ inch between similar elements, in a 20-foot span. Karnak Architecture 2641-43 Ocean Street File:e:\wp 7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 10, 2003 Page 18 Construction The following preliminary recommendations are for the proposed construction, in consideration of our field investigation, laboratory testing and engineering analysis. These construction recommendations are meant as minimums and are not intended to supersede the recommendations of the structural engineer or corrosion specialist: Due to the very low to low expansive soil conditions identified onsite, foundations should be constructed to a minimum depth of 12 inches below lowest adjacent grade. Foundation widths and depths may be constructed per Uniform Building Code (UBC) guidelines (i.e., 18 inches deep for two-story loads}. All footings should be minimally reinforced with two No. 5 reinforcing bars, one placed near the top and one placed near the bottom of the footing. Exterior post supports should be founded at a depth of 18 inches below the lowest adjacent grade and tied to the main foundation system with a grade beam in two directions. Reinforcement should be properly designed by the project structural engineer. A grade beam, reinforced as above, and a minimum of 1 square foot in cross section at least 12 inches wide should be utilized across large entrances, such as garages or double wide doorways. The base of the reinforced grade beam should be at the same elevation as the bottom of adjoining footings. Setbacks Foundations for any structure (including pools, tennis courts, etc.) should be set back from the top of any adjacent descending slope, a distance equal to one-third the height of the slope. Foundations for any adjacent structures, including retaining walls, should be deepened (as necessary) to below a 1 :1 projection upward and away from any proposed lowerfoundation system. This recommendation may not be considered valid, if the additional surcharge imparted by the upper foundation on the lower foundation has been incorporated into the design of the lower foundation. Additional setbacks, not discussed or superseded herein, and presented in the UBC are considered valid. Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 1 o, 2003 Page 19 CONVENTIONAL CONCRETE SLABS ON GRADE Conventional Floor Slabs The following criteria are considered minimum design parameters for the slab and they are in no way intended to supersede design by the structural engineer. Slab criteria provided , do not account for concentrated loads from heavy machinery. Floors in slab areas are assumed to be designed for typical residential floor slabs. Slabs subject to higher or concentrated loads (e.g., columns, walls, etc.) should be properly designed by the project structural engineer. The subgrade soil should be compacted to a minimum 90 percent of the laboratory maximum density. Moisture conditioning is recommended for these soil conditions. The moisture content of the subgrade soils should be equal to or greater than the soils optimum moisture, to a depth of 18 inches below pad grade in the slab areas and verified by this office within 72 hours of pouring slabs and prior to placing visqueen or reinforcement. Slabs should be a minimum of 4 inches thick and be minimally reinforced with No. 4 reinforcing bars on 18 inches centers both ways, or equivalent reinforcement. Reinforcing should be properly supported on chairs or blocks to ensure placement near the vertical midpoint of the slab. Concrete slab weakened plane or expansion joints should be placed in accordance with current standards of practice and no greater than 12 feet apart. Concrete slabs should be underlain with a minimum of 4 inches of sand. In addition, where moisture condensation is undesirable, a vapor barrier consisting of a minimum 6 mil thick, polyvinyl chloride or equivalent membrane, with all laps sealed, should be provided at the mid-point of the sand layer. Exterior Flatwork Exterior walkways, sidewalks, or patios, using concrete slab on grade construction ( excluding traffic pavements), should be designed and constructed in accordance with the following criteria. 1. Slabs should be a minimum 4 inches in thickness. A thickened edge should be considered (12 inches in depth and 4 to 6 inches in thickness) for all flatwork adjacent to landscape areas. ---·--2. --·Slab subgrade should be compacted to a minimum 90 percent relative compaction and moisture conditioned to at or above the soils optimum moisture content. 3. The use of transverse and longitudinal control joints should be considered to help control slab cracking due to concrete shrinkage or expansion. Two of the best ways to control this movement is: 1) add a sufficient amount of reinforcing steel, increasing Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 1 0, 2003 Page 20 tensile strength of the slab; and/or 2) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. We would suggest that the maximum control joint spacing be placed on 5-to 8-foot centers or the smallest dimension of the slab, whichever is least. 4. No traffic should be allowed upon the newly poured concrete slabs until they have .. been properly cured to within 75 percent of design strength. 5. Positive site drainage should be maintained at all times. Adjacent landscaping should be graded to drain into the street, parking area, or other approved area. All surface water should be appropriately directed to areas designed for site drainage. 6 In areas directly adjacent to a continuous source of moisture (i.e. irrigation, planters, etc.), all joints should be sealed with flexible mastic. 7. Concrete used to construct flatwork should be at least ASTM 520-C-2500. DRILLED PIER AND GRADE BEAM FOUNDATIONS The proposed three-story addition may also be supported by drilled, cast-in-place, concrete piers. To improve performance, if retaining walls are proposed on site, they may also utilize a drill pier supported foundation. The drilled pier foundation for the building should gain vertical support from friction and end bearing in suitable soils above the water table. The piers should extend 5 feet into the terrace deposits. The piers should be a minimum 18 inches in diameter and designed based on the vertical load with an allowable ¼-inch of post construction settlement. The structural strength of the piers should be checked by the structural engineer or civil engineer specializing in structural analysis. Total loads may be increased by 1/3 for wind and seismic. Uplift capacities may be computed using ¼ the allowable downward loads (including the concrete pier weight). For planning purposes, the piers may use a skin friction resistance of 250 psf (surface area of the pier). The top 3 feet should not be considered in design. The end bearing of the pier may utilize an additional 1,000 psf, if the bottom of the pier excavation is clean and free of loose debris prior to placing concrete. Lateral load resistance for the drilled pier foundation depends on the stiffness of the surrounding soil, stiffness of the pier shaft, allowable deflection at the pier top and induced --·--·----·-moment in the pier. Lateral load will be provided by passive pressure acting atthe pier cap. An equivalent fluid pressure of 200 pounds per cubic foot (pcf) acting on artificial fill with a maximum of 2,000 psf can be considered for passive resistance. The upper 12 inches of passive resistance for the drilled piers should be neglected unless confined by slabs or pavement. A more refined lateral load capacity may be provided when the pier head conditions (fixed, free), layout and elevations are provided. Drilled piers should be spaced Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 1 0, 2003 Page 21 a minimum of three pier diameters apart (center to center). The effects of pier groups should be evaluated when the preliminary foundation drawings are made available. Pier holes should be drilled straight and plumb. Locations (both plan and elevation) and plumbness should be the contractors responsibility. All loose materials should be removed from the bottom of each pier hole. Concrete and steel reinforcement should be placed in , each pier hole on the same day that the hole is drilled. If a caving sand condition occurs (likely on the site), during or after drilling, the pier hole should be cased. The bottom of the casing should be at least 4 feet below the top of the concrete as the concrete is poured and the casing is withdrawn. Dewatering may be required for concrete placement if significant seepage or groundwater is encountered during construction. This should be considered during project planning. Alternately, tremie concrete placement should be considered. The tops of the drilled piers should be interconnected with grade beams which will aid in resisting differential foundation movement and lateral drift. In general the minimum grade beam size should be 18 inches in width and 12 inches below the finished soil subgrade. The actual design of the grade beams and reinforcement should be performed by the structural engineer or civil engineer specializing in structural analysis. The floor system above the pier and grade beams may be either a structural concrete floor (minimum 6 inches thick) or raised wood floor. Prior to construction, we should review the construction procedure proposed by the contractor. Pier excavations should be observed and approved by us prior to concrete and steel placement. Observations during pier excavations will allow us to correlate the subsurface conditions exposed during construction with that obtained from our borings and make necessary changes in the foundation support and other geotechnical design criteria, if necessary. Drilled pier steel reinforcement cages should have spacers to allow for a minimum spacing of steel from the side of the pier excavation. During pier placement, concrete should not be allowed to free fall more than 5 feet. Concrete used in the foundation should be tested by a qualified materials testing consultant for strength and mix design. SHORING AND BRACING If conventional slab-on-grade foundations are proposed (Alternative No. 1), the existing foundations located on the east and west side of the proposed addition (shown on Plate 1) will require additional support during planned construction at this site. Shoring and bracing for the adjacent building foundations should be evaluated further during design, after plans are made available to this office. Karnak Architecture 2641-43 Ocean Street File:e:\wp 7\3500\3512a.pge GeoSoils, Inc. W.O. 3512-A-SC February 1 o, 2003 Page 22 CORROSION AND CONCRETE TESTS GSI conducted preliminary sampling of near-surface materials for soil corrosivity on the subject site. Laboratory test results indicate that the site materials have a negligible potential for corrosion to concrete and a moderate potential for corrosion to exposed steel. The design criteria presented in Table 19-A-2 and 19-A-3 of UBC (1997 edition) should be ., followed. However, based on the salt environment of the site, the designer should consider the use of Type V concrete. Upon completion of grading, additional testing of soils (including import materials) should be considered prior to the construction of utilities and foundations. Alternative methods and additional comments may be obtained from a qualified corrosion engineer. UTILITIES Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate potential differential settlement. Due to the potential for differential settlement, air conditioning (A/C) units should be supported by slabs that are incorporated into the building foundation (PT slab) or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. A/C waste waterlines should be drained to a suitable outlet. ADDITIONAL RECOMMENDATIONS/DEVELOPMENT CRITERIA Landscape Maintenance and Planting Water has been shown to weaken the inherent strength of soil materials and cause expansion. Slope stability is significantly reduce by overly wet conditions. Plants selected for landscaping should be light weight, deep rooted types which require little water and capable of surviving the prevailing climate. The soils materials should be maintained in a solid to semi-solid state as defined by the material's Atterberg Limits. Only the amount of irrigation necessary to sustain plant life should be provided. Over watering the landscape areas could aversely affect proposed site improvements. We would recommend that any proposed open bottom planters adjacent to proposed structures be eliminated for a minimum distance of 1 O feet. As an alternative, closed bottom type planters could be utilized. An outlet placed in the bottom of the planter could be installed ------• -to direct-drainage away from structures or any exterior fiatwork. From a geotechnical standpoint, leaching is not recommended for establishing landscaping. If the surface soils are processed for the purpose of adding amendments they should be recompacted to 90 percent compaction. For additional information refer to the Homeowner Maintenance Guidelines included in Appendix F. Karnak Architecture 2641-43 Ocean Street File: e:\wp 7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 10, 2003 Page 23 Top-of-bluff stability may be effected by the landscape configuration installed by the owner, architect, and/or landscape architect. Native plants should be selected with deeper taproots, which may improve the stability of the upper portion of coastal bluff and reduce the potential for subaerial erosion. If irrigation systems are utilized, the schedule should be reviewed by the landscape .. architect and should include moisture sensors (or other override devices) embedded into the soil. Landscape work should comply with AB325 and Ordinace 195. Within a period of seven years, existing landscape should be reviewed and renovated as deemed necessary by the landscape architect. Hand planting on the bluff face should be minimized or eliminated. Site Improvements If in the future, any additional improvements are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. This office should be notified in advance of any additional fill placement, regarding the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench, and retaining wall(s) backfills. Drainage Positive site drainage should be maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundation systems and not allowed to pond and/or steep into the ground. Pad drainage should be directed toward the street or other approved area. Roof gutters and down spouts are recommended to control roof runoff. Down spouts should outlet or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. For additional recommendations about maintenance of site drainage refer to Appendix F. Footing Excavations All footing trench excavations should be observed by a representative of this office prior to placing reinforcement. Footing trench or pier spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of -·---------• 90-percent of the laboratory standard (ASTM test method D-1557) if not removed from the site. Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, Ine. W.O. 3512-A-SC February 1 o, 2003 Page 24 Trenching All excavations should be observed by one of our representatives and minimally conform to CAL-OSHA and local safety codes. Utility Trench Backfill Utility trench backfill should be placed to the following standards: 1. All interior utility trench backfill should be brought to near optimum content and compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard (ASTM test method D-1557). As an alternative for shallow (12? inches) under slab trenches, sand having a sand equivalent value of 30 or greater may be utilized. Jetted or flooded backfill as a method of placement is not recommended. Observation/probing/testing should be accomplished to verify the desired results. 2. Exterior trenches in structural areas, beneath hardscape features and in slopes, should be compacted to a minimum of 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used adjacent to perimeter footings or in trenches on slopes. Compaction testing and observation, along with probing should not be performed to verify the desired results. Grading Guidelines Grading should be performed in accordance with the minimum requirements of the Grading Code of the City of Encinitas, and applicable and adopted chapters of the Uniform Building Code (UBC), and the General Grading Guidelines presented in Appendix E of this report. PLAN REVIEW Final site development and foundation plans should be submitted to this office for review and comment, as the plans become available, for the purpose of minimizing any misunderstandings between the plans and recommendations presented herein. In addition, foundation excavations and any additional earthwork construction performed on the site should be observed and tested by this office. If conditions are found to differ substantially from those stated, appropriate recommendations would be offered at that time. Karnak Architecture 2641-43 Ocean Street File:e:\wp 7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 10, 2003 Page 25 LIMITATIONS The materials encountered on the project site and utilized in our laboratory study are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during site grading and construction. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon the site materials observed, selective laboratory testing, and engineering analysis, the conclusion and recommendations are professional opinions. These opinions have been derived in accordance with current standards of practice and no warranty is expressed or implied. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work, testing, or recommendations performed or provided by others. Karnak Architecture 2641-43 Ocean Street File:e:\wp7\3500\3512a.pge GeoSoils, lne. W.O. 3512-A-SC February 1 o, 2003 Page 26 APPENDIX A REFERENCES Blake, T.F., 2000a, EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3-D fault sources; Windows 95/98 version. __ , 2000b, EQSEARCH, A computer program for the estimation of peak horizontal acceleration from California historical earthquake catalogs; Windows 95/98 version. __ , 2000c, FRISKSP, A computer program for the probabilistic estimation of peak acceleration and uniform hazard spectra using 3-D faults as earthquake sources; Windows 95/98 version. Bowles, J.E., 1988, Foundation analysis and design: McGraw-Hill Book Company, New York. California Department of Boating and Waterways and San Diego Association of Governments, Flick, R.E., ed., 1994, Shoreline erosion assessment and atlas of the San Diego region, volume II, December. Campbell, K.W., 1993, Empirical prediction of near-source ground motion from large earthquakes, in Johnson, J.A. Campbell, K.W .. , and Blake, eds., T.F., AEG Short Course, Seismic Hazard Analysis, June 18, 1994. __ , 1985. Strong motion attenuation relations, a ten-year perspective, in, Johnson, J.A., Campbell, K.W., and Blake, T.F., eds., AEG Short Course, Seismic Hazard Analysis, June 18, 1994. Clarke, S.H., Green, H.G., Kennedy, M.P., Vedder, J.G., and Legg, M.R., 1987, Geologic map of the inner-southern California continental margin in Green, H.G., and Kennedy, M.P., eds., California Continental Margin Geologic Map Series: California Department of Conservation, Division of Mines and Geology. Cooper, W.S., 1959, Coastal sand dunes of California: Geological Society of America Memoir. Curran, S.A., and Abbott, P.L., 1994, Fire History of organic fragments Cretacious Point ----------• -------· -Loma· Foundation at La Jolla Bay, in Rosenberg, P .S., ed., Geology and Natural History, Camp Pendelton, United States Marine Corps Base, San Diego County, California: by the San Diego Association of Geologists. Davis, J.F., 1997 Guidelines for evaluating and mitigating seismic hazards in Calfornia: California Division of Mines and Geology, Special Publication 117. GeoSoils, lne. Eisenberg, L.T., 1985, Pleistocene faults and marine terraces, northern San Diego County, in Abbott, P.L., ed., On the Manner of Deposition of the Eocene Strata in Northern San Diego County: San Diego Association of Geologists. Elder-Mills, D., and Artim, E.R., 1982, The Rose Canyon fault; a review, in Abbott, P.L., ed., Geologic Studies in San Diego Association of Geologists. Emery, K.O., and Aubrey, D.G., 1991, eds., Sea levels, land levels, and tide changes, Springer-Verlag Publishers, New York, pp. 175-176 Emery, K.O., and Kuhn, G.G., 1982, Sea cliffs: their processes, profiles, and classification: Geological Society of America Bulletin, v. 93, no 7. __ , 1980, Erosion of rock shores at La Jolla, California, in Marine Geology, v. 37. Fisher, P.J., and Mills, G.I., 1991, The offshore Newport-Inglewood -Rose Canyon fault zone, California: structure, segmentation, and tectonics, in Abbott, P.L., and Elliott, W.J., eds., Environmental Perils -San Diego Region: San Diego Association of Geologists. Fulton, K., 1981, A manual for researching historical coastal erosion in Kuhn, G.G., ed., California Sea Grant Report No. T-CSGCP-003. Gerhard, LC., Harrison, W.E., and Hanson, B.M., eds., 2001, Introduction and overview, in Geological perspectives of global climate change, pp. 231-250. Greensfelder, R. W., 1974, Maximum credible rock acceleration from earthquakes in California: California Division of Mines and Geology, Map Sheet 23. Harff, J.A., Friscbutter, A., Lampe, R., and Meyer, M., 2001, Sealevel changes in the Baltic Sea: interrelation of climatic and geologic process, in Gerhard, LC., Harrison, W.E., and Hanson, B.M., eds., Geological perspectives of global climate change, pp. 231- 250. Hart and Bryant, 1997, Fault-rupture hazard zones in California: California Department of Conservation, Division of Mines and Geology, Special Publication 42. Hausman, M.R., 1990, Engineering principles of ground modification: Mcgraw Hill, Inc., ----------------------New York. Holtz, R.D. and Kovacs, W.D., Undated, An introduction to geotechnical engineering: Prentence-Hall, Englewood Cliffs, New Jersey. Harrer, P.L., 1984, Wave action and related factors for proposed seawall at 6000 Camino de la Costa, dated November 28. Karnak Architecture File:e:\wp 7\3500\3512a.pge GeoSoils, lne. Appendix A Page2 Housner, G. W., 1970, Strong ground motion in Earthquake Engineering, Robert Wiegel, ed., Prentice-Hall. Howell, D.G., Stuart, C.G., Platt, J.P. and Hills, D.J., 1974, Possible strike-slip faulting inthe southern California Borderland: Geological Society of America Geology, v. 2, no. 2. Inman, D.L., 1976, Summary report of man's impact on the California coastal zone; prepared for the Department of Navigation and Ocean Development, State Of California. International Conference of Building Officials, 1997, Uniform building code: Whittier, California. Ishihara, K., 1985 Stability of natural deposits during earthquakes: Proceedings of the Eleventh International Conference on Soil Mechanics and Foundation Engineering: A.A. Balkema Publishers Rotterdam, Netherlands. Jennings, C.W., 1994, Fault activity map of California and adjacent areas: California Division of Mines and Geology, Map Sheet No. 6, scale 1 :750,000. Joyner, W.B. and Boore, D.M., 1982a, Estimation of response-spectral values as functions of magnitude, distance and site conditions, in Johnson, J.A., Campbell, K.W., and Blake, T.F., eds., AEG Short Course, Seismic Hazard Analysis, June 18, 1994. __ , 1982b, Prediction of earthquake response spectra, in Johnson, J.A., Campbell, K.W., and Blake, T.F., eds., AEG Short Course, Seismic Hazard Analysis, June 18, 1994. Kennedy, M.P., 1973, Sea-Cliff erosion at Sunset Cliffs, San Diego: California Geology, 26, February. Kern. J.P., 1977, Origin and history of upper Pleistocene marine terraces, San Diego California, Geological Society of American Bulletin 88. Kuhn, G.G., and Shepard, F.P., 1984, Sea Cliffs, beaches and coastal valleys of San Diego County: some amazing histories and some horrifying implications: University of California Press, Berkeley, California, and London, England. __ , l983, Newly discovered Evidence from the San Diego County area o"f some principles of coastal retreat: Geological Society of America Bulletin, Shore and Beach, January. __ , 1981 ,Should Southern California build defenses against violent storms resulting in lowland flooding as in records of past century: Geological Society of America Bulletin Karnak Architecture File:e:\wp 7\3500\3512a.pge GeoSoils, Ine. Appendix A Page3 ___ , 1980a, Greatly accelerated man-induced coastal erosion and new sources of beach sand, San Onofre State Park and Camp Pendleton, northen San Diego County, California: Geological Society of America Bulletin, Shore and Beach, October. ___ , 1980b Coastal erosion in San Diego County, California, in Edge, B.L., ed., Coastal ., Zone '80, Proceedings of second Symposium on Coastal and Ocean Management held in Hollywood, Florida, on 17-20 November, 1980: American Society of Civil Engineers, V. Ill. ---, 1979a, Accelerated beach-cliff erosion related to unusual storms in southern California: California Geology, March. ___ , 1979,. Coastal erosion in San Diego County, California, in Abbott, P.L. and Elliott, W.J., eds., Earthquakes and other perils San Diego region. Lambe, T.W., 1951, Soil testing for engineers: John Wiley & Sons, New York. Lambe, T.W., and Whitman., R.V., 1969, Soil Mechanics: John Wiley & Sons, New York. Lee, L.J., Schug, D.L. and Raines, G.L. 1990, Seacliff stabilization, Seacliff park (Swami's), beach access stairway, Encinitas, California, in Geotechnical Engineering Case Histories in San Diego County: San Diego Association of Geologists., October 20, Field Trip Guide Book. Leighton and Associates, Inc., 1983, City of San Diego Seismic Safety Study, June. Legg, M.R., 1985, Geologic structure and tectonics of the inner continental borderland offshore northen Baja California, Mexico, unpublished doctoral dissertation submitted to the University of California, Santa Barbara. ___ , 1989, Faulting and seismotectonics of the inner continental borderland west of San Diego, in Roquemore, G., ed., Proceedings, Workshop on the Seismic Risk in the San Diego Region: Special Focus on the Rose Canyon Fault System. Legg, M.R., and Kennedy, M.P., 1991, Oblique divergence and convergence in the California Continental Borderland, in Abbott, P.L., Elliott, W.J., eds., Environmental Perils -San Diego Region: San Diego Association of Geologist. Lindivall, S.C., Rockwell, T.K.., and Lindivall, E.G., 1989, The seismic hazard of San Diego revised: new evidence for magnitude 6+ Holocene earthquakes on the Rose Canyon fault zone, in Roquemore, G., ed., Proceedings, Workshop on The Seismic Risk in the San Diego Region: Special Focus on the Rose Canyon Fault System. Karnak Architecture File:e:\wp7\3500\3512a.pge GeoSoils, lne. Appendix A Page4 Masters, P.M., 1996, Paleocoastlines, ancient harbors and marine archeology: Geology Society of America Bulletin, Shore and Beach, July. Matti, J.C., and Morton, D.M., 1993, Paleogeographic evolution of the San Andreas fault in Southern California: A reconstruction based a new cross-fault correlation, in Powell, R.E., Weldon, R.J. 11, and Matti, J.C., eds., The San Andreas Fault System: _, Displacement, Palinspastic Reconstruction, and Geologic Evolution: Geological Society of America Memoir 178. Matti, J.C., Morton, D.M., and Cox, B.F., 1992, The San Andreas fault system in the vicinity of the central Transverse Ranges province, southern California, in Sieh, K.E., and Matti, J.C., eds., Earthquake Geology San Andreas Fault System, Palm Springs to Palmdale. Mitchell, J.K., 1976, Fundamentals of soil behavior: John Wiley & Sons, Inc. New York. Moore, L.J., Benumof, B.T., and Griggs, G.B., 1999, Coastal erosion hazards in Santa Cruz and San Diego Counties, California, in Crowell, M., and Leatherman, S.P., eds., Coastal erosion mapping and management: Journal of Coastal Research, spec. issue no. 28, 121-139. Morton, D.M., and Matti, J.C., 1993, Extension and contraction within an evolving divergent strike-slip fault complex: The San Andreas and San Jacinto fault zones at their convergence in southern California, in Powell, R.E., Weldon, R.J. II, and Matti, J.C., eds., The San Andreas Fault System: Displacement, Palinspatic Reconstruction, and Geologic Evolution: Geological Society of America Memoir 178. Munk, W.H., and Traylor, M.A., 1947, Refraction of ocean waves: a process linking underwater topography to beach erosion: Journal of Geology, v. LV, no. 1. Naval Facilities Engineering Command, 1986a, Soil Mechanics, design manual 7.01, Change 1 September: United States Navy. ___ , 1986b, Foundations and earth structures, OM 7 .02, Change 1 September: United States Navy. ___ , 1983, Soil Dynamics, deep stabilization, and special geotechnical construction, design manual 7.3, April: United States Navy. Nordstom, C.E., and Inman, D.L., 1973, Beach and cliff erosion in San Diego County, California, in Ross A., and Dowlen, R.J., eds., Studies on the Geology and Geologic Hazards of the Greater San Diego Area, California: the San Diego Association of Geologists, and Association of Engineering Geologists. Karnak Architecture File:e:\wp7\3500\3512a.pge GeoSoils, Inc. Appendix A Page5 Sadigh, K., Egan, J., and Youngs, R., 1987, Predictive ground motion equations reported in Joyner, W.B., and Boore, D.M., 1988, "Measurement, characterization, and prediction of strong ground motion", in Earthquake Engineering and Soil Dynamics II, Recent Advances in Ground Motion Evaluation, Von Thun, J.L., ed.: American Society of Civil Engineers Geotechnical Special Publication No. 20, pp. 43-102. Schumm, S.A., and Mosley, P.M., 1973, Slope Morphology: Dowden, Hutchinson & Ross, Inc. Seed, H.B., 1976, Evalution of soil liquefaction effects on leve.l ground during earthquakes, state-of-art paper, liquefaction problem: Geotechnical Engineering, American Society of Civil Engineers, Preprint 2753, New York. Seed, H.B. and Idriss, I.M., 1982, Ground motions and soil liquefaction during earthquakes: Earthquake Engineering Research Institute monograph. __ , 1971, A simplified procedure for evaluating soil liquefaction potential: American Society of Civil Engineers, JSMFD, v. 197. Seed, H.B., Idriss, I.M., and Arango, I., 1983, Evaluation of liquefaction potential using feild performance data: American Society of Civil Engineers, Journal of Geotechnical Engineering, v. 109. Seed, H.B., Tokimatsu, K., Harder, L.F., and Chung, R.M., 1985, Influence of SPT procedures in soil liquefaction resistance evaluations: Journal of the Geotechnical Engineering Division, American Society of Civil Engineers, v. 111, no. GR12, p. 1425-1445. Shepard, F.P., and Kuhn, G.G., 1983, History of sea arches and remnant stacks of La Jolla California, and their bearing on similar features elsewhere: Marine Geology, v. 51. Shepard, F.P., and Grant, U.S. IV, 1947, Wave erosion along the southern California coast: Geological Society of America Bulletin, v. 58, Shore and Beach, October. Shinn, E.A., Coral reefs and shoreline dipsticks, 2001 in Gerhard, LC., Harrison, W.E., and Hanson, B.M., eds., Geological perspectives in global climate change, pp 251-264. Streiff, D., Schmoll, M., and Artim, E.R., 1982, The Rose Canyon fault at Spindrift Drive, La ····-·Jolla, California,, in Abbott, P.L., ed., Geologic Studies in San Diego: San Diego Association of Geologists. Sowers and Sowers, 1970, Unified soil classification system (After U. S. Waterways Experiment Station and ASTM 02487-667) in Introductory Soil Mechanics, New York. Karnak Architecture File:e:\wp7\3500\3512a.pge GeoSoils, Inc. Appendix A Page6 Sunamura, T., 1977, A relationship between wave-induced cliff erosion and erosive forces of waves: Journal of Geology, v. 85. Terzaghi, K., and Peck. Ralph B., 1967, Soil mechanics in engineering practice: John Wiley and Sons, New York, second edition. Teriman, J.A., 1984, The Rose Canyon fault zone, a review and analysis: The California Department of Conservation, Division of Mines and Geology, Cooperative Agreement EMF-83-k0148. Trenhaile, AS., 1987, The geomorphology of rock coasts: Clarendon Press, Oxford. United States Army Corps of Engineers, 1991, State of the coast report San Diego region, CCSTWS91. __ , 1989, Historic wave and sea level data report San Diego region, CCSTWS 88-6. __ , 1988, Coastal cliff segments San Diego region (1887-1947), CCSTWS 88-6. __ , 1984a, Shore protection manual. __ , 1984b, Nearshore bathymetric survey report, no 1, CCSTWS 84-2. Weber, F.H., 1982, Geologic Map of north-central coastal area of San Diego County, California, showing recent slope failures and pre-development landslides: California Department of Conservation, Division of Mines and Geology, OFR 82-12 LA. Wilson, K.L., 1972, Eocene and related geology of a portion of the San Luis Rey and Encinitas quadrangles, San Diego County, California: unpublished masters thesis, university of California, Riverside. Zeevaert, L., 1972, Foundation engineering for difficult subsoil conditions: Van Nostrand Reinhold Company Regional Offices, New York. Ziony, J.I., 1973, Recency of faulting in the greater San Diego area, California, in Ross, A., and Dowlen, R.J., eds., Studies on the Geology and Geologic Hazards of the Greater San Diego Area, California: San Diego Association of Geologists and Association of Engineering Geologists. Karnak Architecture File:e:\wp7\3500\3512a.pge GeoSoils, lne. Appendix A Page7 TABLE OF CONTENTS PAGE I. SCOPE OF WORK 1 II. SITE DESCRIPTION 2 ---· ---· -· --III. FIELD INVESTIGATION 3 IV. LABORATORY TESTS 4 V. GENERAL GEOLOGIC DESCRIPTION 6 VI. SITE-SPECIFIC GEOLOGIC DESCRIPTION 7 VII. GEOLOGIC HAZARDS 10 VIII. EARTHQUAKE RISK EVALUATION 15 IX. CONCLUSIONS AND RECOMMENDATIONS 17 X. GRADING NOTES 33 XI. LIMITATIONS 34 FIGURES Ia. Vicinity Map Ib. Site Plan and Geologic Map Ic. Cross Section A-A' IIa-f. Exploratory Boring and Handpit Logs III. Laboratory Test Results IV. Foundation Requirements Near Slopes V. Retaining Wall Waterproofing and Drainage Schematic APPENDICES ,---------------A,----UnifieEI SoU Classification System ! , B. EQ Fault Tables and EQ Search Tables C. Modified Mercalli Index D. General Earthwork Specifications Proposed Kiko Residence Carlsbad, California Job No. 02-8201 Page 20 Qa = 1000D+S00W for footings in compacted fill Qa = 1500D+ 750W for footings in formation where "Qa" is the allowable soil bearing capacity (in psf); "D" is the depth of the footing (in feet) as measured from the lowest adjacent grade; and "W" is the width of the footing (in feet). This load-bearing value may be increased one-third for design loads that include wind or seismic analysis. In fill soils, an increase of 500 psf in the allowable bearing value may be allowed for every 1 foot of embedment and for every additional 1 foot in width over the minimum dimensions indicated above, up to a maximum of 5,000 psf. Foundations in formational soils may have an allowable bearing increase of 1,500 psf for each additional foot in depth, and 750 psf for each additional foot in width. The maximum bearing capacity shall not exceed 6,000 psf. 7. The passive earth pressure of the dense natural-ground soils (to be used for design of shallow foundations and footings to resist the lateral forces) shall be based on an Equivalent Fluid Weight of 300 pounds per cubic foot. This passive earth pressure shall only be considered valid for design if the ground adjacent to the foundation structure is essentially level for a distance of at least three times the total depth of the foundation and is comprised of properly compacted fill within the depth of the foundation. •• 8. An allowable Coefficient of Friction of 0.40 times the dead load may be used between the bearing soils and concrete foundations, walls, or floor slabs. Proposed Kiko Residence Carlsbad, California Job No. 02-8201 Page 23 For exterior slabs, we recommend the project Civil/Structural Engineer incorporate isolation joints and sawcuts to at least one-fourth the thickness of the slabs. The joints and cuts, if properly placed, should reduce the potential for random exterior shrinkage cracking. In no case, however, shall control joints be spaced farther than 15 feet apart. Re-entrant corners shall also be provided with control joints or additional steel reinforcing. Due to a number of reasons (such as base preparation, construction techniques, curing procedures, and normal shrinkage of concrete), some cracking of slabs can still be expected. Control joints shall be placed within 12 hours after concrete placement or as soon as the concrete sets and may be cut without aggregate ravelling. Reinforced slabs on-grade shall have every other bar interrupted 3 inches before crossing control joints for an effective weak plane result. To prevent moisture infiltration, all exterior slab joints shall be sealed with elastomeric seal material. The sealant shall be inspected every six months and be properly maintained. Due to the proximity of the ocean, the structural engineer should consider the use of concrete with Cement Type II and a water-cement ratio no higher than 0.40 due to sea water chlorides. For concrete pavement, we recommend that the compressive strength f'c be at least 4,500 psi at 28 days of age and the slab thickness be not less than 5½ inches thick, with control joints no farther than 15 feet or the width of the driveway, whichever is less. Driveway subgrade soils shall be properly compacted and moisture conditioned before any base and/or concrete .----·--··-·· ____ p_la.c.ernent .. -, ---· -·-•• I Page 2 Kennedy, M.P., S.S. Tan, R.H. Chapman and G.W. Chase, 1975, Character and Recency of Faulting, San Diego Metropolitan Area, California, Calif. Div. of Mines and Geology Special Report 123, 33 pp. Kennedy, M.P. and E.E. Welday, 1980, Character and Recency of Faulting Offshore, metropolitan San Diego California, Calif. Div. of Mines and Geology Map Sheet 40, 1:50,000. Kern, J.P. and T.K. Rockwell, 1992, Chronology and Deformation of Quaternary Marine Shorelines, San Diego County, California in Heath, E. and L. Lewis (editors), The Regressive Pleistocene Shoreline, Coastal Southern California, pp. 1-8. Lindvall, S.C. and T.K. Rockwell, 1995, Holocene Activity of the Rose Canyon Fault Zone in San Diego, California, Journal of Geophysical Research, v. 100, no. B-12, p. 24121-24132. McEuen, R.B. and C.J. Pinckney, 1972, Seismic Risk in Oceanside; Transactions of the Oceanside Society of Natural History, Vol. 17, No. 4, 19 July 1972. Moore, G.W. and M.P. Kennedy, 1975, Quaternary Faults in San Diego Bay, California, U.S.Geological Survey Journal of Research, v. 3, p. 589-595. Richter, C.G., 1958, Elementary Seismology, W.H. Freeman and Company, San Francisco, Calif. Rockwell, T.K., D.E. Millman, R.S. McElwain, and D.L. Lamar, 1985, Study of Seismic Activity by Trenching Along the Glen Ivy North Fault, Elsinore Fault Zone, Southern California: Lamar-Merifield Technical Report 85-1, U.S.G.S. Contract 14-08-0001-21376, 19p. Simons, R.S., 1977, Seismicity of San Diego, 1934-1974, Seismological Society of America Bulletin, v. 67, p. 809-826. Tan, S.S., 1995, Landslide Hazards in Southern Part of San Diego Metropolitan Area, San Diego County, Calif. Div. of Mines and Geology Open-file Report 95-03. Toppozada, T.R. and D.L. Parke, 1982, Areas Damaged by California Earthquakes, 1900-1949; Calif. Div. of Mines and Geology, Open-file Report 82-17, Sacramento, Calif. Treiman, J.A., 1993, The Rose Canyon Fault Zone, Southern California, Calif. Div. of Mines and Geology Open-file Report 93-02, 45 pp, 3 plates. "' ~ ul 5 Cl ..J n. i';'.i I 0 lU Cl ~ Cl "' Cl ---·----o ..J f;1 ,12 ~ "' 8 ..J z 0 ~ g 0. X lU / EQUIPMENT QIMENSION & TYPE OF EXCAVATION DATE LOGGED Limited Access Auger Drill Rig 6-inch diameter Boring 4-5-02 SURFACE ELEVATION GROUNDWATER DEPTH LOGGED BY ± 34' Mean Sea Level at 24 feet JKH FIELD DESCRIPTION AND l ~~ ~ >- CLASSIFICATION ~ 2§~ w w I-' LU C:: LU;:-::E c:: ::E -LL. ..J w cri ()::, () I-::, ::, ::, >-::r: 0 ..J DESCRIPTION AND REMARKS ::E .!:: ::i~ ::icn ::E I-I-cc c.. (.) j::: SQ ~'.:2 fu ::E ::E (Grain size, Dens~y. Moisture, Color) cri a.-a.z ~ ;15 ,Q 'w a. 0 0 =, ~ ::E ~□ 0 ::E ::E 'el . ' I FINE TO COARSE SAND, w/ some rock SW ! , .. -fragments, poorly to moderately cemented. '; !., 16-Medium dense to dense. Dry to damp. Light ,• • r· gray-white. -••.•. .. " -.1 •. TERRACE DEPOSITS (Qt} .. -. .. • 0 18-.. ' . . •' -' : .. -\ 1~ -·:. ,•• 20-.. ... . . -. ' . . . . . . . = 22-.. , .. -. " .. · .. -.. 24 ,,. . ' ~ SANDSTONE, well cemented. Dense. Damp . SM -' . Light tan-gray. SANTIAGO FORMATION (Tsb) {'- 26- Bottom@25' - - 28- - - -~ JOB NAME WATER TABLE. Proposed Kiko Residence [gj LOOSE BAG SAMPLE SITE LOCATION [I] IN-PLACE SAMPLE 2649 Ocean Street, Carlsbad, California II JOB NUMBER REVIEWED BY LDR/JAC DRIVE SAMPLE 0 02-8201 C~~ Geotectmfc:al SAND CONE/F.D.T. FIGURE NUMBER EXploratlon, Inc. ~ STANDARD PENETRATION TEST lie ~ \.,. ..., ~ ~ ~ I-' c::i c::i d~ >-□ + .....i be: en ~~ I-• zg 3: !z -::E en_ <: z zo o:::i ;::;; () ~~ a. 0 _,o c1i ~ ?i'.i () CCU 24 2" 50+ 2" LOG No. B-2 ·----·-· - I ill l-o (!) ..J ~ w I @ (!) -, 0. (!) ui (!) 0 ..J 0 " ,;z 0 N a, (!) 0 ..J z 0 i= < a: g a. X UJ r EQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED Limited Access Auger Drill Rig 6-inch diameter Boring 4-5-02 SURFACE ELEVATION GROUNDWATER DEPTH LOGGED BY ± 39' Mean Sea Level at 16 feet JKH FIELD DESCRIPTION AND 15:: '[ >-,Ii! ,Ii! ls'[ CLASSIFICATION t: w □-w ::.~ w 0:: w >-::. 0:: ...J w ui u::, ::::i::, ::::i >-:c 0 _, DESCRIPTION AND REMARKS ~$ ::. !=: '.:i I-::. I-I-co a. (j -en ~ ffi a. ::le ::le (Grain size, Density, Moisture, Color) ui a... !/2 a.z I--w >-<( ,o •w a. 0 Cl en CJ) :::i 6::i: 60 0::. ::.o -~ SIL TY FINE TO MEDIUM SAND, w/ some rock SM fragments and chunks of sandstone. Medium -~ dense. Damp. Red-brown. :--·, ,( -~)C. X FILU 2-;~ TERRACE (Qaf/Qt) -, ~---1' to 2' of fill at the surface. ,>, -,ex· -:... ~( < ·!• 4- -< -] FINE TO MEDIUM SAND, poorly cemented. SP -Medium dense. Damp. Tan-gray and orange. 6-TERRACE DEPOSITS (Qt) - - 8- - - 10-~ FINE TO MEDIUM SAND, w/ slight silt, ----• -sr-=- moderatelywell cemented. Dense. Damp. SM -Red-brown and tan. -TERRACE DEPOSITS (Qt) 12- - - - 14- JOB NAME l'. WATER TABLE • Proposed Kiko Residence ~ LOOSE BAG SAMPLE SITE LOCATION [I] IN-PLACE SAMPLE 2649 Ocean Street, Carlsbad, California JOB NUMBER REVIEWED BY LDR/JAC ■ DRIVE SAMPLE 02-8201 @] ~ Geote-ctmftal SAND CONE/F.D.T. FIGURE NUMBER EXplot'lltlon, Inc. ~ STANDARD PENETRATION TEST ~ lid ' -~ ci ;; ...: T _j ~ ci->-ci wen ~~ ·o I--'W ~~ -;:z a. :r: zo o::::i ~~ UJ~ a... 0 ...JO □-@ (_) CD(.) en= 31 3" 20 2" 53 3" LOG No. B-3 ~ iil l:i (!) .., ~ I 0 w (!) .., 0.. (!) r--.. ---§ I ~ ;.: 0 f/l C) 0 ..J z 0 ~ n: 0 ..J ll. X w / EQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOC-GED Hand Tools, Hand Auger 3' x 3' x 6' Handpit 4-5-02 SURFACE ELEVATION GROUNDWATER DEPTH LOGGED BY ± 15' Mean Sea Level at 5 feet JKH FIELD DESCRIPTION AND ~~ >- CLASSIFICATION ~ ~ isi ,-.: UJ~ w;:-::;;~ :a;>-LL. ...J w :c 0 ...J DESCRIPTION AND REMARKS (/) u::, U1-::, ::, ::, I-:s~ :s-:a; I-:a;-I-CD c.. 0 c..~ i= ~ ~~ c.. ::;; ::;; (Grain size, Density, Moisture, Color) (/) ~~ w >-~ zlll c..O C) en :::i -□ o::;; :a;~ -'. FINE TO MEDIUM SAND, w/ lenses of cobbles SP -.·. (to 6" in diameter). Loose to medium dense. Dry '. to damp. Light gray. -.. -, ' -.. -•• 0 BEACH DEPOSITS (Qb) 1 -b~"\. --o(Y -D. < -~-·? -'. -.. -2-... . . -• ' ' -.. --p\).( ·G\ -[). Cl 3-~ -.. --.. -_,__ FINE TO COARSE SAND, w/ some rock SW -... -. . fragments, poorly cemented . Medium dense. 4-·.• ': Moist to wet. Tan-brown. •,• -•• > -... -:.., , ,\ TERRACE DEPOSITS (Qt) -.. ' -hand-augered from 4' to 6'. -:y· 5-:--:· -... ·---.J :~--, --'·· , ,)• .... --i-"-'--SANDSTONE, well cemented. Dense. Damp . SM ... '.,. 6-- ~ Light tan-gray. I '------SANTIAGO FORMATION (Tsb) ---Bottom@6' -7-------- -. -._y, .. JOB NAME WAT-~R .:r ABLE Proposed Kiko Residence ~ LOOSE BAG SAMPLE SITE LOCATION [I] IN-PLACE SAMPLE 2649 Ocean Street, Carlsbad, California II JOB NUMBER REVIEWED BY LDR/JAC DRIVE SAMPLE ~ 02-8201 ~ Geotedlnfc:af SAND CONE/F.D.T. FIGURE NUMBER Exploration, '"" ~ STANDARD PENETRATION TEST llf ~ ... "I -~ ci ~ c::i >-0 -t ..J c:i-(/) WU) I-• zg s::lz --"W -:a; ~a ~z c.. :c 96 ~~ w* ljS 8 0-CDU Ul= LOG No. HP-1 ~ l:i C!l --' ~ I 0 w C!l EQUIPMENT Hand Tools, Hand Auger DIMENSION & TYPE OF EXCAVATION 3' x 3' x 5' Handpit SURFACE ELEVATION GROUNDWATER DEPTH Not Encountered ± 11' Mean Sea Level FIELD DESCRIPTION AND ~ CLASSIFICATION LL --' UJ :c 0 _, DESCRIPTION AND REMARKS f-co a. a. :::;; :a; (Grain size, Density, Moisture, Color) UJ >-< Cl en en -0 ... '4 FINE TO MEDIUM SAND, w/ lenses of cobble -~ ... (to 6" in diameter). Loose to medium dense. Dry 0 ••• o -. . to damp . Light gray. -. • .. o ,,; 'a Q .!·~-~--~ BEACH DEPOSITS (Qb) -... 1 -.. o· • a -.. ·. , .. •. --.. : .• -po0 •• ( -~i?;o. -ib· c/ -2-~ -a 'O ,Q -.. •. -... ,; ... -·,·. -o. ••, a_ -..... -Q .• Q 3-·.·. :;,'-,1·(; ~u" .... < <? (5 -* -··•. -....... -... . 4-. •,. 0 •• . . -o• • •• -.. -. . -hand-augered from 4.5' to 5'. -fl SILTY SANDSTONE, well cemented. Dense. -·1.t1, Damp . Light tan-gray. • I -~ 5-l.lLl i\ SANTIAGO FORMATION (Tsb\ r --- Bottom@5' --6------- CJ) c..i en ::i SP SM - e:. f§'§: UJ UJ er: UJ ;:-(..):::, (..) f-::s ti; ::Sm a..-a. z •O ' UJ ~:::;; ~Cl DATE LOGGED 4-5-02 LOGGED BY JKH >-~ ,:... ~'§: UJ :::;; er: :::;;~ :::, :::, :::, >-:::;; !::: :::;; f--en -en f--~z o...O o:::;; :::;; [:g ~ 0 ~ ci ci ' ci~ >-ci + \!:: _j en ~~ f-• ~ 0 3:~ -:::E en_ en 0... :c zo a. z o::::i :::EC..J ~e i'.i) 0 --' 0 <Z (..) co (..) !')= fu.-------------------.--JO_B_NA_M_E-------------------------, --~ -----~-WATER--TABLE Proposed Kiko Residence ~ ~ LOOSE BAG SAMPLE SITE LOCATION 2649 Ocean Street, Carlsbad, California ;; m IN-PLACE SAMPLE N ex, C!l II 0 DRIVE SAMPLE --' z 0 0 >= SAND CONE/F.D.T. < c,: 0 ~ --' STANDARD PENETRATION TEST D.. X w JOB NUMBER REVIEWED BY LDR/JAC 1----0_2_-8_20_1 __ --l(r,.(~ Geotectmlcal FIGURE NUMBER ...;.;..__,;;;;.....;.:;.• Exploration, Inc. Ilg ~ LOG No. HP-2 ~ i;j l:i I!) ..J n. X UJ I 0 UJ I!) ii'. I!) ui I!) ,------0 I _., l ~ ' i.: ~ <0 I!) 0 ...J z 0 ~ 0 ...J n. X l1J /" EQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED Hand Tools, Hand Auger 3' X 3' x 4' Handpit 4-5-02 SURFACE ELEVATION GROUNDWATER DEPTH LOGGED BY ± 20' Mean Sea Level Not Encountered JKH FIELD DESCRIPTION AND ~ ~'R >-~ 25 '§: CLASSIFICATION !!..- i-: w w WC:: w;:-::;; 0:: ::;;~ LL __J w ui U=> :sti => => => >-:r: 0 __J DESCRIPTION AND REMARKS :5 I-::;; I-::;; !:: 0:: CXl a.. c..i -Cf) ~~ ::;; ::;; {Grain size, Denstty, Moisture, Color) ui a..!:!! a..z I--w >-c1i ,Q zW a..O Cl Cf) =:i :;J;::;; _C) a::. - I~ SIL TY FINE TO MEDIUM SAND, w/ abundant SM -roots and sandstone fragments. Loose to medium -. dense. Dry to damp. Red-brown and gray-brown. ' -' FILU . -TOPSOIL (Qaf) - ~ , 1 -. X - ~ . -< - ~ :;:_;: -' -. --2-• • I FINE TO MEDIUM SAND, w/ slight silt and SW -•'. , .. .. i. some rock fragments. Medium dense (poorly -• ! ',. -} ... cemented). Damp. Tan-brown and orange. ' -'. 1. -'· f i. TERRACE DEPOSITS (Qbp} -.1., -.... 3-' -I•. ... • • I• -.. ,, .. ' .. -... -' .. '. -•:• : . : -•I 1' ••• 4-, ... ,___ ----Bottom@4' --- 5-------- -----Y.-WATER TABLE JOB NAME Proposed Kiko Residence ~ LOOSE BAG SAMPLE SITE LOCATION IT] IN-PLACE SAMPLE 2649 Ocean Street, Carlsbad, California • JOB NUMBER REVIEWED BY LDR/JAC DRIVE SAMPLE [I] 02-8201 (fja&j-( 0 Geotec:tmlcal SAND CONE/F.D.T. FIGURE NUMBER Exploration, Inc. ~ STANDARD PENETRATION TEST Ith ~ \.. ", ~ C ~ ci ci ci->-ci + _J :l:l IB !:: ::;; zg s:'z cn_ cf: z a.. :c zo o=> ~~ ~!Co riS 8 _,o (Xl(_) CIJ= LOG No. HP-3 .,/ ~ ;;; l-o Cl _, ~ I 0 lU Cl 'EQUIPMENT DIMENSION & TYPE OF EXCAVATION Hand Tools, Hand Auger 3' x 3' x 3' Hand pit SURFACE ELEVATION GROUNDWATER DEPTH ??? Not Encountered FIELD DESCRIPTION AND i-: CLASSIFICATION u. ....J !::l Cf} :c 0 DESCRIPTION AND REMARKS cc a. c.5 I-a. ::;; ::;; (Grain size, Dens~y. Moisture, Color) cri UJ ~ cJi 0 :::i . t =, . SILTY FINE TO MEDIUM SAND, w/ some roots SM -. I., and rock fragments. Loose to medium dense. -' Dry. Tan-gray. -I • t j.:. -.. FILU ',, -... WEATHERED TERRACE DEPOSITS (Qaf} -.... -.... 1 -. ' -poorly cemented . -... -... -i ':. -.·:·. -·'· . t -.. I - 2-.. -.. -.... ' -• .. ---:-:--:-FINE TO MEDIUM SAND, w/ slight silt, SM ,. t ; .. -I . . •• moderately well cemented. Dense. Damp . -,: ~ ;-. Red-brown and orange . -. :·!':, 3-_;.;:_;_ r\ TERRACE DEPOSITS (Qbo) r,___ - - - -Bottom@3' - - - 4- - -- - - - - DATE LOGGED 4-5-02 LOGGED BY JKH ~ ~E ~ ~'[ ~ UJ UJ UJ a: UJ>-::;; a: :;;- U:::l U1-:::) :::> :::)~ ::i ti ::i cii ::,;; I-::,;;--Cf} ~-~ a.-a.Z I--•O • UJ a.O ~ ~::;; ~o a:. ~ Cl U) ,·------8 _, -----.Y.---WAl=ER TABLE JOB NAME -Proposed Kiko Residence 0 "' i2 0 &i Cl 0 ..., z 0 ;:: ~ g ~ w ~ IT] II [I] '--~ LOOSE BAG SAMPLE IN-PLACE SAMPLE DRIVE SAMPLE SAND CONE/F.D.T. STANDARD PENETRATION TEST SITE LOCATION 2649 Ocean Street, Carlsbad, California JOB NUMBER REVIEWED BY LDR/JAC 02-8201 er,~;-. Geotechnlcal FIGURE NUMBER Exploration, Inc. Iii ~ ' ~ -ci ~ ci ' ci-~q + _J UJCf} :z 5l ~~ ... UJ cii~ a. :c <C z zo a. 0 o:::i ~~ ~~ ....,o tiSu CCU Cf}= LOG No. HP-4 ~ "' 6 (!) ..J Q. t.'j I 0 w (!) -, Q. (!) en ' (!) I -------g I ~ .;z_ ;; "' a, 8 ..J z 0 g ..J Q. X w ,, EQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED Hand Tools, Hand Auger 3' x 3' x 6' Handpit 4-5-02 SURFACE ELEVATION GROUNDWATER DEPTH LOGGED BY ± 30' Mean Sea Level Not Encountered JKH FIELD DESCRIPTION AND g~ >-~ ~ §i ~ CLASSIFICATION ~ w ::dl::! WO:: w;:-::;;~ u.. -' w ui U:::> U1-=> => => >-::c 0 -' DESCRIPTION AND REMARKS :'.:i I-:s-~tn ::;; !::: I-CD c.. c.5 c..~ ~~ c.. ~ ::;; (Grain size, Denstty, Moisture, Color) U) c.. S!2 to w cf5 zo zW Cl en :::i _::;; -□ o::;; ::;;~ -/~-t SILTY FINE TO MEDIUM SAND, w/ abundant SM -·~·-.% roots, cobbles and rock fragments. Loose to i ,:,· -"r:911,: medium dense. Dry to damp. Gray-brown. -•' -..,f .~ .. ~ 1 -1I):°i FILL (Qaf} '·-Jt;-;\ -.:t~ -~~) -·~n,-'.."1 I ~~ i -~~ ~;!, 2-J./Z~· -~ii{.: -Drain pipe encountered. -s:;. --,~~ i '"!· -~ SILTY FINE TO MEDIUM SAND, w/ some rock SM \ <l •• -•:~."I fragments and large boulders {to 12" in diameter). --~ q(\~ 3-/i;r :Q Medium dense. Damp. Red-brown. -AG!, -.('l c/ FILL(Qaf} -'(. /4 ,-0: -•tv 4-:\ ~rf, ~ SILTY FINE TO MEDIUM SAND, w/ some roots SM -~ ·~1-1: and organics. Loose to medium dense. Dry. ---'-'--' \ Dark brown. ! SM ., •. • ·. -·'!· .•' ... TOPSOIL 5-..... ~ FINE TO MEDIUM SAND, w/ some coarse rock .o· • • -.. fragments. Medium dense. Damp. Tan-brown. -;. --~--~ -.: .•. .... WEATHERED TERRACE DEPOSITS -• !·. • •• -dense Terrace Deposits encountered on the east . '•. 6-Q ••• ..__ ["\half of the excavation. I I--- - - -Bottom@6' 7- - - - .,Y._ WATER TABLE __ JOB NAME -~*•-Proposed Kiko Residence 0 LOOSE BAG SAMPLE SITE LOCATION ill IN-PLACE SAMPLE 2649 Ocean Street, Carlsbad, California ■ JOB NUMBER REVIEWED BY LDR/JAC DRIVE SAMPLE 0 02-8201 cr;.ce-u Geotechnlcal SAND CONE/F.D.T. FIGURE NUMBER ~ Exploratlan, Inc. ~ STANDARD PENETRATION TEST llj ~ \. 'I ~ C -~ ci ci ci->-□ + ...J U) wen !::: ::i ~ 0 3:!z a:W U)-c.. ~ ::;; 23 zo o=> ~~ ~ 8 _,o <i:Z cou en=- LOG No. HP-5 ,J Kiko TEST.OUT -------------------------EARTHQUAKE SEARCH RESULTS ------------------------- Page 2 -------------------------------------------------------------------------------I I I I TIME I I I SITE I SITEI APPROX. FILEI LAT. I LONG. I DATE I (UTC) IDEPTHIQUAKEI ACC. I MM I DISTANCE CODEI NORTH I WEST I I HM Seel (km)I MAG. I g IINT. mi [km] ----+-------+--------+----------+--------+-----+-----+-------+----+------------ DMG 32.70001116.3000102/24/18921 720 0.0 0.0 6.70 0.016 IV I 68.6(110.5) MGI 34.0000l118.0000 12/25/190311745 0.0 0.0 5.00 0.004 I I 69.0(111.0) DMG 33.2170 116.1330 08/15/1945l175624.o 0.0 5.70 0.007 II I 70.4(113. 3) GSP 34.1400 117.7000 02/28/19901234336.6 5.0 5.20 0.005 II I 70.6(113.6) DMG 33.1900 116.1290 04/09/1968 22859.1 11.1 6.40 0.012 IIII 70.6(113.6) DMG 33.8500 118.2670 03/11/1933 1425 0.0 0.0 5.00 0.004 I I 71.1(114. 4) DMG 34.2000 117.4000 07/22/1899 046 0.0 0.0 5.50 0.006 II 71. 9(115 .6) PAS 33.9980 116.6060107/08/1986 92044.5 11.7 5.60 0.006 II 72.0(115.8) DMG 34.1000 116.8000110/24/1935 1448 7.6 0.0 5.101 0.004 I 72. 2(116.2) DMG 134.2000 117.1000109/20/1907 154 0.0 0.0 6.00 0.008 III 73.2(117.8) DMG 134:1800 116.9200 01/16/1930 034 3.6 0.0 5.10 0.004 I 74.6(120.1) DMG 34.1800 116.9200 01/16/1930 02433.9 0.0 5.20 0.004 I 74.6(120.1) GSP 34.1630 116.8550 06/28/1992 144321.01 6.0 5.30 0.005 II 74. 9(120. 5) DMG 34.1000 116.7000 02/07/1889 520 0.0, 0.0 5.30 0.005 II 74.9(120.5) PAS 34.0610 118.0790 10/01/1987 144220.0 9.5 5.90 0.007 II 75.0(120. 7) DMG 33.1130 116.0370 04/09/1968 3 353.5 5.0 5.20 0.004 I 76.0(122.3) PAS 34.0730 118.0980 10/04/1987 105938.2 8.2 5.30 0.004 I 76.3(122.8) DMG 34.0170 116.5000 07/26/1947 24941.0 0.0 5.10 0.004 I 76.8(123.5) DMG 34.0170 116. 5000 07/25/1947 61949.0 0.0 5.20 0.004 I 76.8(123.5) DMG 34.0170 116.5000 07/25/1947 04631.0 0.0 5.00 0.003 I 76.8(123.5) DMG 34.0170 116.5000 07/24/1947 221046.0 0.0 5.50 0.005 II 76.8(123.5) GSP 34.1950 116.8620 08/17/1992 204152.1 11.0 5.30 0.004 I 76. 8(123. 5) DMG 33.9330 116.3830 12/04/1948 234317.0 0.0 6. 50 0.012 III 77.1(124.1) DMG 34.2700 117.5400 09/12/1970 143053.0 8.0 5.40 0.005 II 77 .4(124. 6) T-A 34.0000 118.2500 09/23/1827 0 0 0.0 0.0 5.00 0.003 I 77 .7(125 .1) T-A 34.0000 118.2500 03/26/1860 0 0 0.0 0.0 5.00 0.003 I 77. 7(125 .1) T-A 34.0000 118.2500 01/10/1856 0 0 0.0 0.0 5.00 0.003 I 77. 7(125 .1) MGI 34.1000 118.1000 07/11/1855 415 0.0 0.0 6.30 0.010 III 77.9(125.4) DMG 33.2310 116.0040 05/26/1957 155933.6 15.1 5.00 0.003 I 77.9(125.4) GSN 34.2030 116.8270 06/28/1992 150530.7 5 .0 6.70 0.013 III 78.0(125.6) DMG 34.20001· 117. 9000 08/28/1889 215 0.0 0.01 5.50 0.005 II 78.4(126.2) DMG 134.3000 117.5000 07/22/1899 2032 0.0 0.01 6.50 0.011 III 79.2(127.4) DMG l32.9670 116.0000 10/22/1942 181326.0 0.01 5.00 0.003 I 79.2 (127. 5) DMG 32.9670 116.0000 10/21/1942 162519.0 0.0 5.00 0.003 I 79.2(127.5) DMG 32.9670 116.0000 10/21/1942 162654.0 0.0 5.00 0.003 I 79.2(127.5) DMG 32.9670 116.0000 10/21/1942 162213.0 0.0 6.50 0.011 III 79.2(127.5) DMG 34. 2670 116.9670 08/29/1943 34513 .o 0.0 5.50 0.005 II 79.5(128.0) GSP 33.8760 116.2670 06/29/1992 160142.8 1.0 5.20 0.004 I 79.6(128.0) MGI 34.0000 118.3000 09/03/1905 540 0.0 0.0 5.30 0.004 I 79.7(128.2) GSP 33.9020 116.2840 07/24/1992 181436.2 9.0 5.00 0.003 I 79.9(128.6) DMG 34.3000 117.6000 07/30/1894 512 0.0 0.0 6.00 0.007 II 80.0(128.8) DMG 32.9830 115.9830 05/23/1942 154729.0 o.o 5.00 0.003 I 80.0(128.8) GSP 134.2390 116.8370 07/09/1992 014357.6 0.0 5.30 0.004 I 80.1(128.9) DMG 132.0000 117.5000 06/24/1939 1627 0.0 0.0 5.00 0.003 I 80.6(129.6) DMG l32.0000 117.5000 05/01/1939 2353 0.0 0.0 5.00 0.003 I 80.6(129.6) DMG 32. 2000 116.5500 11/05/1949 43524.0 0.0 5.10 0.003 I 81. 0(130. 3) --------DMG--34.-2000 -1-16 ,.$-500--11/04/-1949 204238.0 0.0 5.70 0.006 II 81. 0 (130. 3) I GSP 33.9610 116.3180 04/23/1992 045023.0 12.0 6.10 0.008 II 81.1(130. 6) I ' PDG 34.2900 116.9460 02/10/2001 210505.8 9.0 5.10 0.003 I 81.4(131.0) MGI 34.0800 118.2600 07/16/1920 18 8 0.0 0.0 5.00 0.003 I 82.3(132.4) DMG 32. 5000 118.5500102/24/19481 81510.0 0.0 5.30 0.004 I 83.2(133.9) GSP 34.0290 116.3210 08/21/1993l014638.41 9.01 5.00 0.003 I 84.3(135.6) DMG 32.0830 116.6670l11/25/1934I 818 0.01 0.01 5.00 0.003 I 84. 3(135. 7) ◄~ti Page 3 ~z APPENDIX C MODIFIED MERCALLI INDEX ---------·-----·-·-------•--. ~ APPENDIX E • 'GRADING GUIDELINES. GENERAL EARTHWORK AND GRADING GUIDELINES General These guidelines present general procedures and requirements for earthwork and grading as shown on the approved grading plans, including preparation of areas to filled, placement , of fill, installation of subdrains and excavations. The recommendations contained in the geotechnical report are part of the earthwork and grading guidelines and would supersede the provisions contained hereafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new recommendations which could supersede these guidelines or the recommendations contained in the geotechnical report. The contractor is responsible for the satisfactory completion of all earthwork in accordance with provisions of the project plans and specifications. The project soil engineer and engineering geologist (geotechnical consultant) or their representatives should provide observation and testing services, and geotechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnical Consultant Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer and engineering geologist) should be employed for the purpose of observing earthwork procedures and testing the fills for conformance with the recommendations of the geotechnical report, the approved grading plans, and applicable grading codes and ordinances. The geotechnical consultant should provide testing and observation so that determination may be made that the work is being accomplished as specified. It is the responsibility of the contractor to assist the consultants and keep them apprised of anticipated work schedules and changes, so that they may schedule their personnel accordingly. All clean-outs, prepared ground to receive fill, key excavations, and subdrains should be observed and documented by the project engineering geologist and/or soil engineer prior to placing and fill. It is the contractors1s responsibility to notify the engineering geologist and soil engineer when such areas are ready for observation. Laboratory and Field Tests Maximum dry density tests to determine the degree of compaction should be performed in accordance with American Standard Testing Materials test method ASTM designation D- 1557-78. Random field compaction tests should be performed in accordance with test method ASTM designation D-1556-82, D-2937 or D-2922 and D-3017, at intervals of approximately 2 feet of fill height or every 100 cubic yards of fill placed. These criteria would vary depending on the soil conditions and the size of the project. The location and frequency of testing would be at the discretion of the geotechnical consultant. GeoSoils, lne. Contractor's Responsibility All clearing, site preparation, and earthwork performed on the project should be conducted by the contractor, with observation by geotechnical consultants and staged approval by the governing agencies, as applicable. It is the contractor's responsibility to prepare the ground surface to receive the fill, to the satisfaction of the soil engineer, and to place, spread, .. moisture condition, mix and compact the fill in accordance with the recommendations of the soil engineer. The contractor should also remove all major non-earth material considered unsatisfactory by the soil engineer. It is the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the earthwork in accordance with applicable grading guidelines, codes or agency ordinances, and approved grading plans. Sufficient watering apparatus and compaction equipment should be provided by the contractor with due consideration for the fill material, rate of placement, and climatic conditions. If, in the opinion of the geotechnical consultant, unsatisfactory conditions such as questionable weather, excessive oversized rock, or deleterious material, insufficient support equipment, etc., are resulting in a quality of work that is not acceptable, the consultant will inform the contractor, and the contractor is expected to rectify the conditions, and if necessary, stop work until conditions are satisfactory. During construction, the contractor shall properly grade all surfaces to maintain good drainage and prevent ponding of water. The contractor shall take remedial measures to control surface water and to prevent erosion of graded areas until such time as permanent drainage and erosion control measures have been installed. SITE PREPARATION All major vegetation, including brush, trees, thick grasses, organic debris, and other deleterious material should be removed and disposed of off-site. These removals must be concluded prior to placing fill. Existing fill, soil, alluvium, colluvium, or rock materials determined by the soil engineer or engineering geologist as being unsuitable in-place should be removed prior to fill placement. Depending upon the soil conditions, these materials may be reused as compacted fills. Any materials incorporated as part of the compacted fills should be approved by the soil engineer. Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks,· wells·, ptpelines, or other structures not located prior to grading are to be removed or treated in a manner recommended by the soil engineer. Soft, dry, spongy, highly fractured, or otherwise unsuitable ground extending to such a depth that surface processing cannot adequately improve the condition should be overexcavated down to firm ground and approved by the soil engineer before compaction and filling operations continue. Overexcavated and processed soils which have been properly mixed and moisture Karnak Architecture File:e:\wp7\3500\3512a.pge GeoSoils, lne. Appendix E Page2 conditioned should be re-compacted to the minimum relative compaction as specified in these guidelines. Existing ground which is determined to be satisfactory for support of the fills should be scarified to a minimum depth of 6 inches or as directed by the soil engineer. After the scarified ground is brought to optimum moisture content or greater and mixed, the materials .. should be compacted as specified herein. If the scarified zone is grater that 6 inches in depth, it may be necessary to remove the excess and place the material in lifts restricted to about 6 inches in compacted thickness. Existing ground which is not satisfactory to support compacted fill should be overexcavated as required in the geotechnical report or by the on-site soils engineer and/or engineering geologist. Scarification, disc harrowing, or other acceptable form of mixing should continue until the soils are broken down and free of large lumps or clods, until the working surface is reasonably uniform and free from ruts, hollow, hummocks, or other uneven features which would inhibit compaction as described previously. Where fills are to be placed on ground with slopes steeper than 5: 1 (horizontal to vertical), the ground should be stepped or benched. The lowest bench, which will act as a key, should be a minimum of 15 feet wide and should be at least 2 feet deep into firm material, and approved by the soil engineer and/or engineering geologist. In fill over cut slope conditions, the recommended minimum width of the lowest bench or key is also 15 feet with the key founded on firm material, as designated by the Geotechnical Consultant. As a general rule, unless specifically recommended otherwise by the Soil Engineer, the minimum width of fill keys should be approximately equal to ½ the height of the slope. Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable material. Benching may be used to remove unsuitable materials, although it is understood that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered for unsuitable materials in excess of 4 feet in thickness. All areas to receive fill, including processed areas, removal areas, and the toe of fill benches should be observed and approved by the soil engineer and/or engineering geologist prior to placement offill. Fills may then be properly placed and compacted until design grades (elevations) are attained. COMPACTED FILLS Any earth materials imported or excavated on the property may be utilized in the fill provided that each material has been determined to be suitable by the soil engineer. These materials should be free of roots, tree branches, other organic matter or other deleterious materials. All unsuitable materials should be removed from the fill as directed by the soil engineer. Soils of poor gradation, undesirable expansion potential, or substandard strength Karnak Architecture File:e:\wp7\3500\3512a.pge CeoSoils, lne. Appendix E Page3 characteristics may be designated by the consultant as unsuitable and may require blending with other soils to seNe as a satisfactory fill material. Fill materials derived from benching operations should be dispersed throughout the fill area and blended with other bedrock derived material. Benching operations should not result in the benched material being placed only within a single equipment width away from the .. fill/bedrock contact. Oversized materials defined as rock or other irreducible materials with a maximum dimension greater than 12 inches should not be buried or placed in fills unless the location of materials and disposal methods are specifically approved by the soil engineer. Oversized material should be taken off-site or placed in accordance with recommendations of the soil engineer in areas designated as suitable for rock disposal. Oversized material should not be placed within 1 O feet vertically of finish grade (elevation) or within 20 feet horizontally of slope faces. To facilitate future trenching, rock should not be placed within the range of foundation excavations, future utilities, or underground construction unless specifically approved by the soil engineer and/or the developers representative. If import material is required for grading, representative samples of the materials to be utilized as compacted fill should be analyzed in the laboratory by the soil engineer to determine its physical properties. If any material other than that previously tested is encountered during grading, an appropriate analysis of this material should be conducted by the soil engineer as soon as possible. Approved fill material should be placed in areas prepared to receive fill in near horizontal layers that when compacted should not exceed 6 inches in thickness. The soil engineer may approve thick lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer should be spread evenly and blended to attain uniformity of material and moisture suitable for compaction. Fill layers at a moisture content less than optimum should be watered and mixed, and wet fill layers should be aerated by scarification or should be blended with drier material. Moisture condition, blending, and mixing of the fill layer should continue until the fill materials have a uniform moisture content at or above optimum moisture. After each layer has been evenly spread, moisture conditioned and mixed, it should be ---uniformly compacted to a minimum of 90 percent of maximum density as determined by ASTM test designation, D-1557-78, or as otherwise recommended by the soil engineer. Compaction equipment should be adequately sized and should be specifically designed for soil compaction or of proven reliability to efficiently achieve the specified degree of compaction. Karnak Architecture File:e:\wp7\3500\3512a.pge GeoSoils, lne. Appendix E Page4 Where tests indicate that the density of any layer of fill, or portion thereof, is below the required relative compaction, or improper moisture is in evidence, the particular layer or portion shall be re-worked until the required density and/or moisture content has been attained. No additional fill shall be placed in an area until the last placed lift of fill has been tested and found to meet the density and moisture requirements, and is approved by the soil engineer, Compaction of slopes should be accomplished by over-building a minimum of 3 feet horizontally, and subsequently trimming back to the design slope configuration. Testing shall be performed as the fill is elevated to evaluate compaction as the fill core is being developed. Special efforts may be necessary to attain the specified compaction in the fill slope zone. Final slope shaping should be performed by trimming and removing loose materials with appropriate equipment. A final determination of fill slope compaction should be based on observation and/or testing of the finished slope face. Where compacted fill slopes are designed steeper than 2:1 (horizontal to vertical), specific material types, a higher minimum relative compaction, and special grading procedures, may be recommended. If an alternative to over-building and cutting back the compacted fill slopes is selected, then special effort should be made to achieve the required compaction in the outer 1 O feet of each lift of fill by undertaking the following: 1. An extra piece of equipment consisting of a heavy short shanked sheepsfoot should be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The sheepsfoot roller should also be used to roll perpendicular to the slopes, and extend out over the slope to provide adequate compaction to the face of the slope. 2. Loose fill should not be spilled out over the face of the slope as each lift is compacted. Any loose fill spilled over a previously completed slope face should be trimmed off or be subject to re-rolling. 3. Field compaction tests will be made in the outer (horizontal) 2 to 8 feet of the slope at appropriate vertical intervals, subsequent to compaction operations. 4. After completion of the slope, the slope face should be shaped with a small tractor and then re-rolled with a sheepsfoot to achieve compaction to near the slope face. Subsequent to testing to verify compaction, the slopes should be grid-rolled to achieve compaction to the slope face. Final testing should be used to confirm compaction after grid rolling. 5. Where testing indicates less than adequate compaction, the contractor will be responsible to rip, water, mix and re-compact the slope material as necessary to achieve compaction. Additional testing should be performed to verify compaction. Karnak Architecture File:e:\wp7\3500\3512a.pge GeoSoils, Inc. Appendix E Page5 6. Erosion control and drainage devices should be designed by the project civil engineer in compliance with ordinances of the controlling governmental agencies, and/or in accordance with the recommendation of the soil engineer or engineering geologist. SUBDRAIN INSTALLATION Subdrains should be installed in approved ground in accordance with the approximate alignment and details indicated by the geotechnical consultant. Subdrain locations or materials should not be changed or modified without approval of the geotechnical consultant. The soil engineer and/or engineering geologist may recommend and direct changes in subdrain line, grade and drain material in the field, pending exposed conditions. The location of constructed subdrains should be recorded by the project civil engineer. EXCAVATIONS Excavations and cut slopes should be examined during grading by the engineering geologist. If directed by the engineering geologist, further excavations or overexcavation and re-filling of cut areas should be performed and/or remedial grading of cut slopes should be performed. When fill over cut slopes are to be graded, unless otherwise approved, the cut portion of the slope should be observed by the engineering geologist prior to placement of materials for construction of the fill portion of the slope. The engineering geologist should observe all cut slopes and should be notified by the contractor when cut slopes are started. If, during the course of grading, unforeseen adverse or potential adverse geologic conditions are encountered, the engineering geologist and soil engineer should investigate, evaluate and make recommendations to treat these problems. The need for cut slope buttressing or stabilizing should be based on in-grading evaluation by the engineering geologist, whether anticipated or not. Unless otherwise specified in soil and geological reports, no cut slopes should be excavated higher or steeper than that allowed by the ordinances of controlling governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractors responsibility. Erosion control and drainage devices should be designed by the project civil engineer and should be constructed in compliance with the ordinances of the controlling governmental agencies, and/or in accordance with the recommendations of the soil engineer or engineering geologist. Karnak Architecture File:e:\wp 7\3500\3512a.pge GeoSoils, lne. Appendix E Page6 COMPLETION Observation, testing and consultation by the geotechnical consultant should be conducted during the grading operations in order to state an opinion that all cut and filled areas are graded in accordance with the approved project specifications. After completion of grading and after the soil engineer and engineering geologist have finished their observations of the work, final reports should be submitted subject to review by the controlling governmental agencies. No further excavation or filling should be undertaken without prior notification of the soil engineer and/or engineering geologist. All finished cut and fill slopes should be protected from erosion and/or be planted in accordance with the project specifications and/or as recommended by a landscape architect. Such protection and/or planning should be undertaken as soon as practical after completion of grading. JOB SAFETY General At GeoSoils, Inc. (GSI) getting the job done safely is of primary concern. The following is the company's safety considerations for use by all employees on multi-employer construction sites. On ground personnel are at highest risk of injury and possible fatality on grading and construction projects. GSI recognizes that construction activities will vary on each site and that site safety is the prime responsibility of the contractor; however, everyone must be safety conscious and responsible at all times. To achieve our goal of avoiding accidents, cooperation between the client, the contractor and GSI personnel must be maintained. In an effort to minimize risks associated with geotechnical testing and observation, the following precautions are to be implemented for the safety offield personnel on grading and construction projects: Safety Meetings: GSI field personnel are directed to attend contractors regularly scheduled and documented safety meetings. Safety Vests: Safety vests are provided for and are to be worn by GSI personnel at all times when they are working in the field. Safety Flags: Two safety flags are provided to GSI field technicians; one is to be affixed to the vehicle when on site, the other is to be placed atop the spoil pile on all test pits. Karnak Architecture Appendix E File:e:\wp7\3500\3512a.pge Page 7 GeoSoils, lne. Flashing Lights: All vehicles stationary in the grading area shall use rotating or flashing amber beacon, or strobe lights, on the vehicle during all field testing. While operating a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. In the event that the contractor's representative observes any of our personnel not following _, the above, we request that it be brought to the attention of our office. Test Pits Location, Orientation and Clearance The technician is responsible for selecting test pit locations. A primary concern should be the technicians's safety. Efforts will be made to coordinate locations with the grading contractors authorized representative, and to select locations following or behind the established traffic pattern, preferably outside of current traffic. The contractors authorized representative (dump man, operator, supervisor, grade checker, etc.) should direct excavation of the pit and safety during the test period. Of paramount concern should be the soil technicians safety and obtaining enough tests to represent the fill. Test pits should be excavated so that the spoil pile is placed away form oncoming traffic, whenever possible. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates the fill be maintained in a driveable condition. Alternatively, the contractor may wish to park a piece of equipment in front of the test holes, particularly in small fill areas or those with limited access. A zone of non-encroachment should be established for all test pits. No grading equipment should enter this zone during the testing procedure. The zone should extend approximately 50 feet outward from the center of the test pit. This zone is established for safety and to avoid excessive ground vibration which typically decreased test results. When taking slope tests the technician should park the vehicle directly above or below the test location. If this is not possible, a prominent flag should be placed at the top of the slope. The contractor's representative should effectively keep all equipment at a safe operation distance (e.g., 50 feet) away from the slope during this testing. The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter of the fill in a highly visible location, well away from the equipment traffic pattern. The contractor should inform our personnei of all changes to haul roads, cut and fiil areas or other factors that may affect site access and site safety. In the event that the technicians safety is jeopardized or compromised as a result of the contractors failure to comply with any of the above, the technician is required, by company policy, to immediately withdraw and notify his/her supervisor. The grading contractors representative will eventually be contacted in an effort to effect a solution. However, in the Karnak Architecture File:e:\wp 7\3500\3512a.pge GeoSoils, lne. Appendix E Page 8 • interim, no further testing will be performed until the situation is rectified. Any fill place can be considered unacceptable and subject to reprocessing, recompaction or removal. In the event that the soil technician does not comply with the above or other established safety guidelines, we request that the contractor brings this to his/her attention and notify this office. Effective communication and coordination between the contractors representative and the soils technician is strongly encouraged in order to implement the above safety plan. Trench and Vertical Excavation It is the contractor's responsibility to provide safe access into trenches where compaction testing is needed. Our personnel are directed not to enter any excavation or vertical cut which: 1) is 5 feet or deeper unless shored or laid back; 2) displays any evidence of instability, has any loose rock or other debris which could fall into the trench; or 3) displays any other evidence of any unsafe conditions regardless of depth. All trench excavations or vertical cuts in excess of 5 feet deep, which any person enters, should be shored or laid back. Trench access should be provided in accordance with CAL-OSHA and/or state and local standards. Our personnel are directed not to enter any trench by being lowered or "riding down11 on the equipment. If the contractor fails to provide safe access to trenches for compaction testing, our company policy requires that the soil technician withdraw and notify his/her supervisor. The contractors representative will eventually be contacted in an effort to effect a solution. All backfill not tested due to safety concerns or other reasons could be subject to reprocessing and/or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the contractor and owner/developer on notice to immediately correct the situation. If corrective steps are not taken, GSI then has an obligation to notify CAL-OSHA and/or the proper authorities. Karnak Architecture File:e:\wp 7\3500\3512a.pge GeoSoils, lne. Appendix E Page9 GUIDELINES FOR THE HOMEOWNER Tips for the Homeowner Homesites, in general, and hillside lots, in particular, need maintenance to continue to function and retain their value. Many homeowners are unaware of this and allow _, deterioration of their property. In addition to one's own property, the homeowner may be subject to liability for damage occurring to neighboring properties as a result of his negligence. It is, therefore, important to familiarize homeowners with some guidelines for maintenance of their properties and make them aware of the importance of maintenance. Nature slowly wears away land, but human activities such as construction increase the rate of erosion 200, even 2,000 times that amount. When vegetation or other objects are removed that hold soil in place, the soil is exposed to the action of wind and water and increase its chances of eroding. The following maintenance guidelines are provided for the protection of the homeowner's investment, and should be employed throughout the year. 3. Care should be taken that slopes, terraces, berms (ridges at crown of slopes), and proper lot drainage are not disturbed. Surface drainage should be conducted from the rear yard to the street by a graded swale through the side yard, or alternative approved devices. 4. In general, roof and yard runoff should be conducted to either the street or storm drain by nonerosive devices such as sidewalks, drainage pipes, ground gutters, and driveways. Drainage systems should not be altered without expert consultation. 5. All drains should be kept cleaned and unclogged, including gutters and downspouts. Terrace drains or gunite ditches should be kept free of debris to allow proper drainage. During heavy rain periods, performance of the drainage system should be inspected. Problems, such as gullying and ponding, if observed, should be corrected as soon as possible. 6. Any leakage from pools, water lines, etc. or bypassing of drains should be repaired as soon as possible. 7. Animal burrows should be filled inasmuch as they may cause diversion of surface runoff,-promote accelerated erosion, and even trigger shallow soil failures. 8. Slopes should not be altered without expert consultation. Whenever a homeowner plans a significant topographic modification of the slope, a qualified geotechnical consultant should be contacted. GeoSoils, lne. 9. If plans for modification of cut, fill or natural slopes within a property are considered, an engineering geologist should be consulted. Any oversteepening may result in a need for expensive retaining devices. Undercutting of the bottom of a slope might possibly lead to slope instability or failure and should not be undertaken without expert consultation. 10. If unusual cracking, settling, or earth slippage occurs on the property, the homeowner should consult a qualified soil engineer or an engineering geologist immediately. 11. The most common causes of slope erosion and shallow slope failures are as follows: • Gross neglect of the care and maintenance of the slopes and drainage devices. • Inadequate and/or improper planting. (Barren areas should be replanted as soon as possible). • Excessive or insufficient irrigation or diversion of runoff over the slope. • Foot traffic on slopes destroying vegetation and exposing soil to erosion potential. 12. Homeowners should not let conditions on their property create a problem for their neighbors. Cooperation with neighbors could prevent problems, and also increase the aesthetic attractiveness of the properties. Winter Alert It is especially important to "winterize" your property by mid-September. Don't wait until spring to put in landscaping. You need winter protection. Final landscaping can be done later. Inexpensive measures installed by mid-September will give you protection quickly that will last all during the wet season. • Check before storms to see that drains, gutters, downspouts, and ditches are not clogged by leaves and rubble. Check after major storms to be sure drains are clear and vegetation is holding on slopes. Repair as necessary. • Spot seed any bare areas. Broadcast seeds or use a mechanical seeder. A typical slope or bare area can be done in less than an hour. Karnak Architecture File:e:\wp 7\3500\3512a.pge GeoSoils, Ine. Appendix F Page2 • • • • • • Give seeds a boost with fertilizer . Mulch if you can, with grass clippings and leaves, bark chips or straw . Use netting to hold soil and seeds on steep slopes . Check with your landscape architect or local nursery for advice . Prepare berms and ditched to drain surface runoff water away from problem areas such as steep, bare slopes. Prepare bare areas on slopes for seeding by raking the surface to loosen and roughen soil so it will hold seeds. CONSTRUCTION 1. Plan construction activities during spring and summer, so that erosion control measures can be in place when rain comes. 2. Examine your site carefully before building. Be aware of the slope, drainage patterns and soil types. Proper site design will help ypu avoid expensive stabilization work. 3. Preserve existing vegetation as much as possible. Vegetation will naturally curb erosion, improve the appearance value of your property, and reduce the cost of landscaping later. 4. Use fencing to protect plans from fill material and traffic. If you have to pave near trees, do so with permeable asphalt or porous paving blocks. 5. Minimize the length and steepness of slopes by benching, terracing, or constructing diversion structures. Landscape benched areas to stabilize the slope and improve its appearance. 6. As soon as possible after grading a site, plant vegetation on all areas that are not paved or otherwise covered. TEMPORARY MEASURES TO STABILIZE SOIL Grass provides the cheapest and most effective short-term erosion control. It grows quickly and covers the ground completely. To find the best seed mixtures and plants for your area, check with your local landscape architect, local nursery, or the U.S. Department of Agriculture Soil Conservation Service. Karnak Architecture File: e:\wp 7\3500\3512a.pge GeoSoils, lne. Appendix F Page3 Mulches hold soil moisture and provide ground protection from rain damage. They also provide a favorable environment for starting and growing plants. Easy-to-obtain mulches are grass clippings, leaves, sawdust, bark chips, and straw. Straw Mulch is nearly 100 percent effective when held in place by spraying with an organic glue or wood fiber (tackifliers), by punching it into the soil with a shovel or roller, or by ., tacking a netting over it. Commercial applications of wood fibers combined with various seeds and fertilizers (hydraulic mulching) are effective in stabilizing sloped areas. Hydraulic mulching with a tackifier should be done in two separate applications: the first composed of seed fertilizer and half the mulch, the second composed of the remaining mulch and tackifier. Commercial hydraulic mulch applicators-who also provide other erosion control services-are listed under "landscaping" in the phone book. Mats of excelsior, jute netting, and plastic sheets can be effective temporary covers, but they must be in contact with the soil and fastened securely to work effectively. Roof drainage can be collected in barrels or storage containers or routed into lawns, planter boxes, and gardens. Be sure to cover stored water so you don't collect mosquitos. Excessive runoff should be directed away from your house. Too much water can damage trees and make foundations unstable. STRUCTURAL RUNOFF CONTROLS Even with proper timing and planting, you may need to protect disturbed areas from rainfall until the plants have time to establish themselves. Or you may need permanent ways to transport water across your property so that it doesn't cause erosion. To keep water from carrying soil from your site and dumping it to nearby lots, streets, streams and channels, you need ways to reduce its volume and speed. Some examples of what you might use are: 1. Rip-rap (rock lining) -to protect channel banks from erosive water flow. 2. Sediment trap -to stop runoff carrying sediment and trap the sediment. 3. Storm drain outlet protection -to reduce the speed of water flowing from a pipe onto open ground or into a natural channel. 4. Diversion dike or perimeter dike -to divert excess water to places where it can be disposed of properly. Karnak Architecture File:e:\wp7\3500\3512a.pge GeoSoils, Ine. Appendix F Page4 5. Straw bale dike -to stop and detain sediment from small unprotected areas (a short term measure). 6. Perimeter swale -to divert runoff from a disturbed area or contain runoff within a disturbed area. 7. Grade stabilization structure -to carry concentrated runoff down a slope. Karnak Architecture File:e:\wp 7\3500\3512a.pge GeoSoils, lne. Appendix F Pages I I I I I I I I I I I I I I I I I I I ~SKELLY ENGINEERING November 11, 2002 Ms. Joan Russell C/O Robert Richardson Karnak Planning and Design 2820 State Street Carlsbad, CA 92008 SUBJECT: Wave Action & Coastal Hazard Study 2641-43 Ocean Street, Carlsbad. Dear Ms. Russell: At your request, we are pleased to present the following letter report concerning wave action and the vulnerability to coastal hazards at the subject property. INTRODUCTION The subject site, located at 2641-43 Ocean Street, Carlsbad, California, lies on top of a wave cut sea cliff which backs a low sand and cobble beach. The lot is about 50 feet in width along the ocean parallel property line. The seaward portion of the property is protected from wave attack by a quarry stone revetment (see Photograph~·stThe beach in front of the site currently consists of sand, covering cobbles that ovet_~x)l formational sandstone. The beach in this area was nourished by the regional beach replenishment project in the Fall of 2001. Much of that nourishment sand is still in the beach profile above low water. The nourishment sand thickness on the beach varies from 1 foot near the shoreline to over 5 feet near the revetment toe. Just landward of the western property line the sand and cobble layer is about 4 ± feet thick. Below the cobble layer is the Santiago Formation, an Eocene bedrock material. This site, and neighboring Carlsbad beaches, are situated along a moderately high wave energy portion of the Southern California coast. This report constitutes an investigation of the wave and water level conditions expected at the site in consequence of extreme storm and wave action. It also provides conclusions and recommendations regarding the stability of the site and vulnerability to coastal hazards. Finally, this report provides a preliminary design, and design parameters for a new vertical seawall at the site. 619 S. VULCAN AVE, #214B ENCINITAS, CA 92024 PHONE 760 942-8379 fax 942-3686 I I I I I I I I I I I I I I I I I I I ~ SKELLY ENGINEERING 4 OCEANOGRAPHIC DESIGN PARAMETERS The wave, wind and water level data used in the design analysis are taken from the historical data reported in USACOE Coast of California Storm and Tidal Wave Study and updated as necessary. The beach profile information was taken from nautical charts and the beach profile data taken from the SAN DAG regional beach profile monitoring program. Other oceanographic information is based upon our experience and knowledge of the area. Beach Slopes and Maximum Scour Depth The slope of the beach face, the nearshore slope and the maximum scour depth are used in the coastal processes analysis for the project. The beach slope was measured during the time of the site inspection. Due to the presence of the sand nourishment the actual beach slope was about 1/10 and the nearshore slope to water depths of about 20 feet is 1/40. The maximum scour depth is not determined by the lowest water but rather by the materials that make up the beach. There is a significant cobble layer beneath the existing beach sand. Once the sand is eroded and transported offshore the cobble layer is exposed. The cobble layer is very resistant to wave transport and remains intact even under extreme wave conditions. Based upon direct observation of nearby beaches during the 1982-83 El Nino winter a conservative maximum scour elevation is about-1.0' MSL. It should be noted that this scour elevation is used only for extreme wave run up and wave force analysis and noHhe necessarily the scour elevation used for the footing design of the seawall. The onshore wind speed was chosen to be 40 knots. Water Level The following table is from the NOAA website for tidal datums and elevations for the La Jolla Scripps Pier. This is valid for the Carlsbad shoreline. • HIGHEST OBSERVED WATER LEVEL (08/08/1983) = 7.81 MEAN HIGHER HIGH WATER (MHHW) = 5.37 MEAN HIGH WATER (MHW) = 4.62 -MEAN TIDE LEVEL (MTL) = 2.77 * NATIONAL GEODETIC VERTICAL DATUM-1929 (NGVD) = 2.56 MEAN LOW WATER (MLW) = 0.93 MEAN LOWER LOW WATER (MLLW) = 0.00 LOWEST OBSERVED WATER LEVEL (12/17/1933) = -2.60 Relative to mean sea level MSL=NGVD29 and based upon the available data, the 619 S. VULCAN AVE, #214B ENCINITAS, CA 92024 PHONE 760 942-8379 fax 942-3686 I I I I I I I I I I I I I I I I I I I ~ SKELLY ENGINEERING 5 highest observed water level is +5.25' MSL( 7.81' MLLW). The lowest observed water level is -5.21' MSL. During storm conditions the sea surface rises along the shoreline (super-elevation) and allows waves to break closer to the shoreline and runup on the beach to the proposed seawall. Superelevation of the sea surface can be accounted for by: wave set-up (1 to 2.5 feet), wind set-up and inverse barometer (0.5 to 1.5 feet), wave group effects ( 1 to 2.5 feet) and El Nino effects (0.5 to 1.0 feet). These conditions rarely occur simultaneously. The EPA estimates an 8 -1 0 inch rise in sea level over the next 75 years (Titus and Narayanan, 1995). The extreme water elevation used in this analysis is +6.0 MSL (100 year recurrence water level). This is basically the highest observed water elevation of +5.25' MSL plus the predicted sea level rise of 0. 75 feet. Waves The San Diego North County shoreline, and this site, has experienced a series of storms over the years. These events have impacted coastal property and beaches depending upon the severity of the storm, the direction of wave approach and the local shoreline orientation. During the 1982-83 El Nino winter the beach fronting this site was severely eroded and large waves occurred during very high water levels. The existing revetment was overtopped but there was no significant damage to the improvements behind the revetment. The design wave is not the largest wave to come into the area. The larger waves break offshore of the beach and lose most of their energy before reaching the shoreline. The design wave for the analysis uses the maximum still water level and maximum scour depth to determine the maximum water depth at the toe of the site (or structure). This water depth is used to compute the maximum breaking wave height at the toe. This wave will provide the maximum run up and wave force on the proposed seawall. Again, historical storms account for much higher wave heights but those waves break offshore and do not impact the site as much as the wave breaking at the toe of the structure. If the total water depth is 7 feet, based upon a maximum scour depth at the toe of the beach/cobble slope of-1.0' MSL and a water elevation of +6.0' MSL, then the gesign wave heigbtwou.ld be about 6 feet. Wave Force Analysis The wave forces on the existing revetment are countered by the size of the stone. The broken wave force on a vertical seawall is calculated using the methods outlined on pages 7-192 to 7-198 of the US Army Corps of Engineers Shore Protection Manual 1984 edition. The d_ynamic_c_o_mpQD~nt of the wave force is wdbhJ2 = (62.4)(5.2)(3.2)/2 =:519 .!Qlf:t. The hydrqstatic-component is w(ds +he)= 62.4(8.2)= 499 lb/ft. So the total force for the broken wave is about 1,000 lb/ft. Because the largest waves will break before they 619 S. VULCAN A VE, #214B ENCINITAS, CA 92024 PHONE 760 942-8379 fax 942-3686 I I I I I I I I I I I I I I I I I I I ~SKELLY ENGINEERING PP YI)\• A.' ~ \'" l.i: U}(,vt (•"" H. "1J/k-1-fj' :, N'e 1CSHeop 's PR0,1 0 ': ,-, B 1n-t. 1 reach the wall, the design wave force used will be for the broken wave with a force of about 1,000 lb/ft of wall. This force is primarily absorbed by the earth/fill behind the wall. It is very important to point out that the wave forces occur over a very short period of time (less than a second) and much of the force is absorbed/reflected by the concrete that the seawall is made from. The force does not have enough time to fully develop and fully transfer throughout structure. In addition, the earth forces and hydrostatic forces, from the soil and water behind the wall, will counter the wave forces on the ocean side of the wall. WAVE RUNUP AND OVERTOPPING ANALYSIS As waves encounter the beach in front of this section of shoreline the water rushes up the beach and may runup the proposed the seawall. Often, wave runup strongly influences the design and the cost of coastal projects. Wave runup is defined as the vertical height above the still water level to which a wave will rise on a structure of infinite height. Overtopping is the rate at which the runup water flo~over the top of a finite height structure. For the purpose of the analysis the seawall height was chosen to be +1§.0' MSL. This is the height of the seawall proposed on the property to the south and for other seawalls along the beach. Wave runup and overtopping for the proposed project is calculated using the United States Army Corps of Engineers Automated Coastal Engineering System, ACES. ACES is an interactive computer based design and analysis system in the field of coastal engineering. The methods to calculate run up and overtopping implemented within this ACES application are discussed in greater detail in Chapter 7 of the Shore Protection Manual (1984). The ACES analysis was performed on oceanographic conditions that represent a typical 100+ year recurrence interval. Table I is the ACES output for these design conditions. Table I AUTOMATED COASTAL ENGINEERING SYSTEM ... Version 1.02 10/29/2002 14:44 Project: WAVE RUNUP AND OVERTOPPING 2643 OCEAN STREET VERTICAL·WALL WAVE RUNUP AND OVERTOPPING ON IMPERMEABLE STRUCTURES Item Unit Value Wave Height at Toe Hi: ft 6.000 Wave Period T: sec 18.000 COTAN of Nearshore Slope 60.000 Water Depth at Toe ds: ft 7.000 COTAN of Structure Slope 0.000 Structure Height Above Toe hs: ft 19.000 Deepwater. Wave Height HO: ft 3. 401 Relative Height (ds/H0): 2.058 Wave Steepness (H0/gTA2): o. 326E-03 Wave Runup R: ft 30.876 Onshore Wind Velocity U: ft/sec 67.512 Overtopping Coefficient Alpha: 0.700E-01 Overtopping Coefficient Qstar0: o.700E-01 Overtopping Rate Q: ftA3/s-ft 4.157 Smooth Slope Runup and Overtopping 619 S. VULCAN AVE, #214B ENCINITAS, CA 92024 PHONE760942-8379 fax942-3686 I I I I I I I I I I I I I I I I I I I I ~ SKELLY ENGINEERING 7 The calculated overtopping rate is about4.2 ft3/sec-ftofwall. Once the wave runup water comes over the top of the wall it does not have enough energy to runup to higher elevations. This water is manageable with a typical wall drainage system. The amount overtopping water can be reduced significantly with a reentrant feature at about elevation ~0\1",.... +16.5' MSL on the face of the wall. The proposed design has such a feature. ,,, 5.,,->~a.;_· ·\ iv C.I\ <. t,. I..'{ ... ,l ' -<• CONCLUSIONS r,,,G,P{,\·0 Ii;. l.il;. ;,t: n -.J M~, ( oJLV l><i' -ro fa.'~')V ' o\'. 11 _. ( 131':;-__ 1.11e~/'\\i::. • /~ has--bee-n subject to wave attack from extreme wave runup in the past~ ( resulting in some erosion of the toe of the slope. rwave runup can reach as hig·h as approximafely +19' MS[-on the existing revetment. '?A.N•'>-: ()1>L .J.\i,:wJ "F _ //Y,fA,-.) f~ot>'\ VS1M:> f.o:.Jt f6'u-.l\ ()(J... (v"\(:,i,Jl;ilH-1 Of l~1rJ6 )1_1;:,1\::. 11'-lt:;i"•✓i w liv\ SMA u ~r .-1r:,, t 1... ' • The properties to-either side of the site have shore protection either in the form of a seawall/bulkhead or a quarry stone revetment. • The site needs some form of shore protection. The proposed seawall will occupy less area on the beach than the existing revetment. 'PR.uv,i)~ 51ic {)lA,J l t.;I ,·,-c..·,-,-5l 'i .JI>,,...,_ L0<.4JF') j,N R_E1--.,tfl1>,V 17) RG VE1M~ ,,;,. RECOMMENDATIONS ■ Long term stability of the site and the adjacent properties will depend on the prevention of the slope from wave attack. The shore/slope protection proposed is a vertical seawall roughly in line with the proposed seawall to the south and slightly setback from the toe of the existing revetment. . .,,J f'\~· f\1.,,._ The vertical seawall should be constructed of steel reinforced concrete. The~!\" 5 ':'1µ,hi-.\ seawall should be located at the western property line (or just landward) and be 1'> io).~V founded into the formational material at about elevation +5' MSL to a depth of about ~'\-, ■ 4 feet. The top of the seawall should be about +18.0' MSL to minimize overtopping. ■ There is rip rap protection on the property .Qf-tf:le-north of the site and a vertical concrete seawall on the property-le-the south of the site. The proposed shore protection will tie into the structures at both sides. The proposed seawall will abut the proposed seawall to the south but not be physically connected unless the connection is engineered. If both walls are constructed at the same time they may be connected as one wall. The proposed seawall will return back along the northern property line for a minimum distance of about 15 feet with the quarry stones from the revetement to the north resting against this return wall. Wave reflection will only 619 S. VULCAN AVE, #214B ENCINITAS, CA 92024 PHONE 760942-8379 fax942-3686