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MS 04-18; EUCALYPTUS LANE; PRELIMINARY GEOTECHNICAL EVALUTATION; 2004-05-26
U(Dll tb I ( -. -f •. PRELIMINARY GEOTECHNICAL EVALUATION APN 208-040-05-00,4998 EUCALYPTUS LANE CITY OF CARLSBAD; SAN DIEGO COUNTY, CALIFORNIA FOR: FAMILY REAL ESTATE ENTERPRISES 560 HIGHWAY, 1O1, SUITE 1. ENCINITAS, CALIFORNIA 92024 W.O.4333-A-SC. MAY 26,2004 •' Geotechnical • Geologic' • Environmental S9 0 Geotechnical • Geologic • Environmental - 5741 Palmer Way • Carlsbad, California 92008 • (760) 438-3155 • FAX (760) 931-0915 May 26, 2004 S W.O. 4333-A-SC Family Real Estate Enterprises 560 Highway 101, Suite 1 Encinitas, California 92024 Attention: Ms. Rachel D. Mullin Subject: Preliminary Geotechnical Evaluation, APN 208-040-05-00,4998 Eucalyptus - Lane, City of Carlsbad, San Diego County, California r Dear Ms. Mullin: In accordance with your request, GeoSoils, Inc. (GSI) has performed a preliminary geotechnical evaluation of the subject site. The purpose of the study was to evaluate the onsite soils and geologic conditions and their effects on the proposed site development from a geotechnical viewpoint. EXECUTIVE SUMMARY Based on our review of the available data (see Appendix A), field exploration, laboratory .1 testing, and geologic analysis, residential development of the property appears to be feasible from a geotechoical viewpoint, provided the recommendations presented in the text of this report are properly incorporated into the design and construction of the project. i The most significant elements of this study are summarized below: Removal of all existing undocumented artificial fill and the upper weathered terrace deposits will be necessary prior to fill placement. Depths of removals are outlined - in the Conclusions and Recommendations section of this report. In general, the site may be characterized as being underlain by Quaternary-aged terrace deposits, I which are mantled on the west portion of the property by at least 13 feet of U potentially compressible undocumented artificial fill. Weathered terrace deposits, generally on the order of 1 to 2 feet thick, should also be removed. Locally deeper L removals should be expected due to variability in weathering and limited test pit data. [ • Based on the available data, and due to the erosional features observed in the near vertical, natural slope, located on the north side of the property, a minimum 1:1 horizontal to vertical (h:v) setback from the base of the descending slope is recommended for any proposed development in this area. Continued erosion and maintenance in this area should be anticipated and incorporated in project planning and design. The expansion potential of tested onsite soils is very low. Conventional foundations may likely be utilized for these soil conditions; however, based on field mapping in the vicinity of the site, the presence of numerous paleoliquefaction features ("sand blows," liquefaction craters, sand filled fissures and injection dikes, sand vents, etc.), may exist within the site. Potential liquefaction of such areas in the future that may impact surface improvements is considered very low, provided that the recommendations presented in this report are incorporated into the design and construction of the project. Mitigation for structures may be provided by the use of post-tensioned slabs. Mitigation in other areas may be accomplished by overexcavation and/or geotextiles, as evaluated in the field during grading, based on proposed development and use. If paleoliquefaction features exist, post-tensioned foundations would be most suitable for this project. However, this would be based on conditions disclosed during grading. At the time of this report, corrosion testing results had not been received for the subject site. An addendum report, presenting those results, will be provided when lab testing is complete. In general, and based upon the available data to date, groundwater is not expected to be a major factor in development of the site; however, perched water may occur during construction and/or after site development, and should be anticipated. Any settlement-sensitive improvements supported or within the influence of the existing fill associated within Eucalyptus Lane, may be subject to distress. Our evaluation in1icates there are no known active faults crossing the site. The seismic acceleration values and design parameters provided herein should be considered during the design of the proposed development. Adverse geologic features that would preclude project feasibility were not encountered. The recommendations presented in this report should be incorporated into the design and construction considerations of the project. Family Real Estate Enterprises W.O. 4333ASC F1Ie:e:\wp9\4300\4333a.pge Page Two GeoSoils, Inc. I The opportunity to be of service is greatly appreciated. If you have any questions concerning this report, or if we may be of further assistance, please do not hesitate to contact any of the undersigned Respectfully submitted, GeoSoils, Inc. DONNA GOOLE'( * I * No. 7571 Donna Gooley i-CA\Y \% NO. 1340 Ce;!Md COAX, ohn P. Franklin St Ben Shahrvini 5 gir Engineering Geologis, Geotechnical Engineer, GE 2296 DG/JPF/BBS/jk 0 Distribution: (3) Addressee 1. Ii Family Real Estate Enterprises W.O. 333ASC I File:e:\wp9\4300\4333&pge • Page Three ' L GeoSoils, Inc. TABLE OF CONTENTS SCOPE OF SERVICES ...................................................1 SITE CONDITIONS/PROPOSED DEVELOPMENT ..............................1 FIELD STUDIES .........................................................3 REGIONAL GEOLOGY ...................................................3 EARTH MATERIALS ......................................................3 Artificial Fill - Undocumented (Map Symbol - Afu) ........................3 Terrace Deposits (Map Symbol - Qt) ...................................5 FAULTING AND REGIONAL SEISMICITY .....................................5 Faulting..........................................................5 Seismicity... Pa rameters . . ............................................7 Seismic Shaking Parameters. ...........................................8 Seismic Hazards ...................................................8 GROUNDWATER ........................................................9 LIQUEFACTION POTENTIAL ..............................................9 LABORATORY TESTING ..................................................10 General.........................................................10 Moisture-Density Relations ..........................................10 Shear Testing ................................................... 10 Expansion Potential ...............................................11 Corrosion Testing .................................................11 CONCLUSIONS ........................................................11 EARTHWORK CONSTRUCTION RECOMMENDATIONS .......................11 General.........................................................11 Site Preparation ..................................................12 Removals (Unsuitable Surficial Materials) ..............................12 Fill Placement ....................................................12 Transitions/Overexcavation .........................................13 Subdrains.......................................................13 Slope Considerations and Slope Design ...............................13 RECOMMENDATIONS - FOUNDATIONS ....................................14 Preliminary Foundation Design ...................................... 14 Bearing Value ..............................................14 Lateral Pressure .............................................15 Foundation Settlement ..............................................15 GeoSoils, Inc. Footing Setbacks . 15 Construction .....................................................15 Very Low Expansion Potential (E.I. 0 to 20) .......................16 POST-TENSIONED SLAB SYSTEMS ........................................17 Post-Tensioning Institute Method ....................................17 UTILITIES..............................................................18 WALL DESIGN PARAMETERS ............................................19 Conventional Retaining Walls .........................................19 Restrained Walls ..............................................19 Cantilevered Walls ...........................................19 Retaining Wall Backfill and Drainage ...................................20 Wall/Retaining Wall Footing Transitions ...............................20 TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS ..........................24 SlopeCreep .....................................................24 Top of Slope Walls/Fences .........................................24 DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS .......................26 DEVELOPMENT CRITERIA ................................................28 Slope Deformation ................................................28 Slope Maintenance and Planting .....................................28 Drainage........................................................29 Erosion Control ...................................................29 Landscape Maintenance ...........................................29 Gutters and Downspouts ............................................30 Subsurface and Surface Water ......................................30 Site Improvements ................................................30 TileFlooring .....................................................31 Additional Grading ................................................31 Footing Trench Excavation .........................................31 Trenching.......................................................31 Utility Trench Backfill ...............................................31 SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING.........................................................32 OTHER DESIGN PROFESSIONALS/CONSULTANTS ..........................33 LIMITATIONS ..........................................................33 Family Real Estate Enterprises Table of Contents FiIe:e:\wp9\4300\4333a.pge • Page ii GeoSolls, Inc. FIGURES: Figure 1 - Site Location Map .........................................2 Figure 2 - Geotechnical Map ..........................................4 Figure 3- California Fault Map ........................................6 Detail 1 - Typical Retaining Wall backfill and Drainage Detail ..............21 Detail 2- Retaining Wall Backfill and Subdrain detail Geotextile Drain .......22 Detail 3- Retaining Wall and Subdrain Detail Clean Sand Backfill ...........23 ATTACHMENTS: Appendix A - References ...................................Rear of Text Appendix B - Test Pit Logs ..................................Rear of Text Appendix C - Site Photographs ...............................Rear of Text Appendix D - EQFAULT, EQSEARCH, and FRISKSP ............Rear of Text Appendix E - General Earthwork and Grading Guidelines .........Rear of Text Family Real Estate Enterprises Table of Contents FIIe:e:\wp9\4300\4333a.pge . Page iii GeoSoils, Inc. PRELIMINARY GEOTECHNICAL EVALUATION APN 208-040-05-00,4998 EUCALYPTUS LANE CITY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA SCOPE OF SERVICES The scope of our services has included the following: Review of the available geologic literature for the site and vicinity (see Appendix A). Subsurface exploration consisting of excavation of two exploratory test pits with a backhoe for geotechnical logging and sampling (see Appendices B and C). Laboratory testing of representative soil samples collected during our subsurface exploration program. 4. General areal seismicity evaluation (see Appendix D). Appropriate engineering and geologic analysis of data collected and preparation of this report. SITE CONDITIONS/PROPOSED DEVELOPMENT The site consists of a roughly rectangular property divided into five lots. Four of the lots are vacant and a two-story residence occupies the fifth lot. The property is located on the north side of Eucalyptus Lane, south of El Camino Real in the City of Carlsbad, California (see Figure 1, Site Location Map). Residential property exists to the south and west. Topographically, the site slopes to the south with elevations ranging from approximately 80 feet to 100 feet Mean Sea Level (MSL). Drainage appears to be directed southward toward Eucalyptus Lane GSI reviewed a compaction report available at the City of Carlsbad Engineering Department, for the subdivision and Eucalyptus Lane located south of the subject property; however, there was no field density test location map available for our review. According to the City of Carlsbad computer records, the fill slope located on the south portion of the subject property was constructed in conjunction with the construction of Eucalyptus Lane; however, according to discussions with Mr. James Brown, Principle Engineer at Geocon, the fill slope was not constructed as a structural slope and no field density testing was performed during placement of the fill for the slope on the subject property. Proposed site development is anticipated to consist of construction of single-family residences, as well as underground utility improvements. It is anticipated that the planned buildings will use continuous footings and slab-on-grade floors with wood-frame and/or masonry block construction. Building loads are assumed to be typical for this type of relatively light structure. It is also our understanding that sewage disposal is proposed to be accommodated by tying into the regional municipal system. -. GeoSoils, Inc. 3-D TopoQuads Copyright i 1999 DeLorine Yarmouth, ME 94096 -- aSg L / rr ie Hjh• AG \U A H E ,/ 332 it It SITE (\ A (1 "S. / ' Country Club \ \' --•.• / 7 I o/ _). ' ---i ,., -->--- ./f flL/ : •1, / T7 Base Map: San Luis Rey Quadrangle, California--San Diego Co., 7.5 Minute Series (Topographic), 1968 (photo revised 1975), by USGS, 1:2000 _1 .CARLa/O \\ ARLE STRORG CIR C.R SUTER ".o. RDR R CS1ESTMJT - Z000 RD CMIEO c S -' , _Sr AV I I AI SHEAID opl' PA 4P RD PL .1900 S ITE 47, EA c GPRS OS' i HILLSID VX - EL c( r. 0R4NCH0 C4RLSBAD - A ZRXE rs F0 VIE s1j"NY 05 ol r VT AV RD San Dieao County Street Guide and Directory. 2004 Edition, by Base Mn Thp Thnms guide. - Thomas Bros. Maps, pages 1106 and 1107, 1:1/2 mile Reproduced with permission granted by Thomas Bros. Maps. This map I. copyrighted by Thom.. Bros. Maps. It Is unlawful to copy, or reproduce all or any part thereof, whether for personal use or resale, without permission. All rights reserved. I W.O. SO, 4333-A-SC 4 SITE LOCATION MAP rq Figure 1 I) lfl I: FIELD STUDIES fl Field studies conducted by GSl consisted of geologic mapping of the site, and the I excavation of three exploratory test pits with a backhoe for evaluation of near-surface soil and geologic conditions. The test pits were logged by a geologist from our firm, who collected representative bulk and undisturbed samples from the test pits for appropriate laboratory testing. The test pit logs are presented in Appendix B. The locations of the test -. pits are presented on Figure 2. REGIONAL GEOLOGY The subject property is located within a prominent natural geomorphic province in - southwestern California known as the Peninsular Ranges. It is characterized by steep, elongated mountain ranges and valleys that trend northwesterly. The mountain ranges are underlain by basement rocks consisting of pre-Cretaceous. metasedimentary rocks, -. Jurassic metavolcanic rocks, and Cretaceous plutonic rocks of the southern California batholith. I In the San Diego region, deposition occurred during the Cretaceous Period and Cenozoic Era in the continental margin of a forearc basin. Sediments, derived from Cretaceous-age plutonic rocks and Jurassic-age volcanic rocks, were deposited into the narrow, steep, coastal plain and continental margin of the basin. These rocks have been uplifted, eroded, and deeply incised. During early Pleistocene time, a broad coastal plain was developed from the deposition of marine and terrestrial terrace deposits. During mid to late Pleistocene time, this plain was uplifted, eroded, and incised. Alluvial deposits have since filled the lower valleys, and young marine sediments are currently being deposited/eroded within coastal and beach areas. The site is generally underlain by terrace deposits. EARTH MATERIALS. Earth materials onsite consist of undocumented artificial fill and Pleistocene-age terrace deposits. A description of each material type is presented in the following discussion. Artificial Fill - Undocumented (MaD Symbol - AN) Undocumented artificial fill underlies the south portion of the site to a depth of at least 13 feet below existing ground surface. The undocumented artificial fill materials encountered onsite consist of light brown, silty sand. The materials generally were dry and loose. These fill materials contain abundant deleterious debris, consisting of large pieces of asphalt and concrete, metal pipe and metal pieces, large tree trunks and roots, etc. (see Photographs, Appendix C). Surficial erosional features, such as large sinkholes and deep gullies, were observed throughout the area where undocumented artificial fill exists. These Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 F1Ie:e:wp9\4300\4333a.pge Page 3 GeoSoils, Inc. - -.----. — — . I I £id.t Nay,, LOT •' Former se REAL R I Ii(Li 1I I >11 s I TTT"s\/T">x)' •\\. LOT I :ic.area tank still present j ón)roPert TPt: TD:2 I L 1"1 0 LOT / afu TOOT I ; I .--- - PINE I lI1 P&D Consultants Inc. $224 UI II.SsIIIlt OEM MW CmIif. 9110$ 20' 0 20-40-60- 1 LrLi feet MULLIN SUBDIVISION Conceptual Lotting Plan APN: 208-040-05-00 4998 Eucalyptus Lone Carlsbad. California 92008 -' LEGEND I. Z01IIMO CWTEIRA I. SC1SAO(S /.- 1#011T: 20' 20C 5-10 OR los 01 LOT 220Th PEAR: 2 lIlIES SIDE YAI22 BUXOM COVERAGE - 402 I2IOlgU&l LOT 220124 - 20 LOT 2901)4 TO LENGTH RATIO (1:3 OR LESS) & W02AL PLAN — 29.24. 0-4 OV/AC 2.2 01)/AC (020227)4 CONSTRAINED OWNtA1) I. OW0$AY RC11E% I. COASTAL ZONE 2. ADJA 24(010110* 5E01424T OF CA2t(01D COASTAl. ZONE DATED 1-29-53 - UftLO S 00014EN? Or THE LCP 3 I2U.STOE DEVELOPMENT PERMIT 4. 22.09t ANALYSIS NI. ACREAGE: 1.99 /- AC. NOTE. TOCRAPNT 12024 RECORD INFORMATION CRANING CT-90—I3 LEGEND afu Artificial fill - undocumented at Quaternary-age terrace deposits 0000 / Approximate location of geologic contact _____ Approximate location of TP-2 exploratory test pit with total TD:2 depth in feet RIVERSIDE CO. ORANGE Co. . SAN DIEGO CO. [~~GEOTEICH NICAL MAP Figure 2 materials are considered unsuitable for the support of settlement-sensitive improvements in their existing state. Terrace Deposits (Map Symbol - Qt) Pleistocene-age terrace deposits underlie the northern portion of the site at the surface. Where encountered, these materials are typically orange brown, dry to moist, and medium dense to dense. Terrace deposits are considered suitable for structural support; however, the weathered upper 1 to 2 feet should be removed and compacted or reprocessed in place. Based on our site exploration, terrace deposits appear relatively massive. As observed in the natural, near-vertical slope located on the north side of the property, bedding structures appear to be relatively horizontal. Elsewhere in the vicinity, it has been our experience that bedding structures within terrace deposits are relatively flat lying and therefore adverse bedding conditions are not anticipated. Erosional features, Such as undermining, significant talus at the base of slope, and erosion along horizontal bedding planes, were observed in the natural slope located on the north side of the property (see Photographs, Appendix C). Semi-vertical tensional cracks were also observed in this natural slope. FAULTING AND REGIONAL SEISMICITY Faulting The site is situated in a region of active as well as potentially-active faults. Our review indicates that there are no known active faults crossing the site within the areas proposed for development (Jennings, 1994), 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 active and would have an effect on.the site in the form of ground shaking should they be the source of an earthquake. These faults 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 Figure 3 (California Fault Map). The possibility of ground acceleration or shaking at the site may be considered as approximately similar to the southern California region as a whole. The following table lists the major faults and fault zones in southern California that should -. have a significant effect on the site should they experience significant activity. II - Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 F1Ie:e:\wp9\4300\4333a.pge Page 5 GeoSoils, Inc. CALIFORNIA FAULT MAP Eucalyptus 1000 800 700 600 500 400 300 100 "III.- '-ZIII- -III, • 100 200 300 400 500 600 W.O. 4333-A-SC Figure 3 GeoSoils, Inc. F ABBREVIATED FAULT NAME APPROXIMATE DISTANCE I MILES (KM) Elsinore - Julian 14.0 (22.5) Elsinore - Temecula 16.0 (25.7) Rose Canyon 18.3 (29.5) Newport-Inglewood (offshore) 21.9 (35.2) Earthquake Valley 27.4 (44.1) Coronado Bank 33.0 (53.1) Selsmlcitv The acceleration-attenuation relations of Sadigh, et al. (1997) Horizontal Soil, Bozorgnia, Campbell, and Niazi (1999) Horizontal-Soil-Correlation, and Campbell and Bozorgnia (1997 Rev.) Soft Rock have been incorporated into EQFAULT (Blake, 2000a). 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 (1981, 1982a, 1982b, 1988, 1990), Bozorgnia, Campbell, and Niazi (1999), and Campbell and Bozorgnia (1997). EQFAULT is -a computer program by Thomas F. Blake (2000a), 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 one of many user-selected acceleration-attenuation relationsthat are contained in EQFAULT. Based on the EQFAULT program, peak horizontal ground accelerations from an upper bound event at the site may be on the order of 0.29g to 0.31g. Historical site seismicity was evaluated with the acceleration-attenuation relations of Campbell and Bozorgnia (1997 Rev.) Soft Rock and the computer program EQSEARCH (Blake, 2000b). This program performs a search of the historical earthquake records for magnitude 5.0 to 9.0 seismic events within a 100-mile radius, between the years 1800 through December 2003. Based on the selected acceleration-attenuation relationship, a peak horizontal ground acceleration is estimated, which may have effected the site during the specific event listed. Based on the available data and the attenuation relationship used, the estimated maximum (peak) site acceleration during the period 1800 through 2003 was 0.17g. Site specific probability of exceeding various peak horizontal ground accelerations and a seismic recurrence curve are also estimated/generated from the historical data. Computer printouts of pertinent portions of the EQSEARCH program are presented in Appendix D. Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 F1Ie:e:\wp9\4300\4333a.pge Page 7 I . GeoSoils, Inc. A probabilistic seismic hazards analyses was performed using FRISKSP (Blake, 2000c), which models earthquake sources as three-dimensional planes and evaluates the site specific probabilities of exceedance for given peak acceleration levels or pseudo-relative velocity levels. Based on a review of these data, and considering the relative seismic activity of the southern California region, a peak horizontal ground acceleration of 0.26g was calculated. This value was chosen as it corresponds to a 10 percent probability of exceedance in 50 years (or a 475-year return period). Seismic Shaking Parameters Based on the site conditions, Chapter 16 of the Uniform Building Code ([UBC], International Conference of Building Officials [ICBO], 1997), the following seismic parameters are provided: Seismic zone (per Figure 16-2*) 4 Seismic Zone Factor (per Table 161*) 0.40 Soil Profile Type (per Table 16-0) S0 Seismic Coefficient C0 (per Table 16-Q*) 0.44 Na Seismic Coefficient C (per Table 16-R*) 0.64 N Near Source Factor N0 (per Table 16-S*) 1.0 Near Source Factor N (per Table 16-T*) 1.0 Seismic Source Type (per Table 16-U*) B Distance to Seismic Source 14.0 mi (22.5 km) Upper Bound Earthquake (Elsinore - Julian) MW 7.1 * Figure and table references from Chapter 16 of the UBC (ICBO, 1997). Seismic Hazards The following list includes other seismic related hazards that have been considered during our evaluation of the site. The hazards listed are considered negligible and/or completely mitigated as a result of site location, soil characteristics, and typical site development procedures: Tsunami Dynamic Settlement Surface Fault Rupture Ground Lurching or Shallow Ground Rupture Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 F1Ie:e:\wp9\4300\4333a.pge Page 8 GeoSolls, Inc. It is important-to keep in perspective that in the event of a maximum probable or credible earthquake occurring on any of the nearby major faults, strong ground shaking would occur in the subject site's general area. Potential damage to any structure(s) would likely I be greatest from the vibrations and impelling force caused by the inertia of a structure's mass than from those induced by the hazards considered above. This potential would be 1 no greater than that for other existing structures and improvements in the immediate vicinity. GROUNDWATER I Subsurface water was not encountered within the property during field work performed in preparation of this report. Subsurface water is not anticipated to adversely affect site development, provided that the recommendations contained in this report are incorporated into final design and construction. These observations reflect site conditions at the time of our investigation and do not preclude future changes in local groundwater conditions r from excessive irrigation, precipitation, or that were not obvious, at the time of our investigation. Regional groundwater is estimated to be at least 50 feet in depth, below the site. Seeps, springs, or other indications of a high groundwater level were not noted on the subject property during the time of our field investigation. However, seepage may occur locally (as the result of heavy precipitation or irrigation) in areas where any fill soils overlie terrace deposits or impermeable soils. Such conditions may occur during grading or after the site is developed, and should be anticipated.. LIQUEFACTION POTENTIAL Seismically-induced liquefaction is a phenomenon in which cyclic stresses, produced by earthquake-induced ground motion, create excess pore pressures in soils. The soils may thereby acquire a high degree of mobility, and lead to lateral movement, sliding, sand boils, consolidation and settlement of loose sediments, and other damaging deformations. This phenomenon occurs only below the watertable; but after liquefaction has developed, it can propagate upward into overlying, non-saturated soil as excess pore water dissipates. Typically, liquefaction has a relatively low potential at depths greater than 45 feet and is virtually unknown below a depth of 60 feet. The condition of liquefaction has two principal effects. One is the consolidation of loose sediments with resultant settlement of the ground surface. The other effect is lateral sliding. Significant permanent lateral movement generally occurs only when there is significant differential loading, such as fill or natural ground slopes. No such loading conditions exist onsite. Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 FIIe:e:\wp9\4300\4333a.pge Page 9 GeoSoils, Inc. Liquefaction susceptibility is related to numerous factors and the following conditions should be concurrently present for liquefaction to occur: 1) sediments must be relatively young in age and not have developed a large amount of cementation; 2) sediments generally consist of medium to fine grained relatively cohesionless sands; 3) the sediments must have low relative density; 4) free groundwater must be present in the sediment; and 5) the site must experience a seismic event of a sufficient duration and magnitude, to induce straining of soil particles. Since at least one or two of the five required concurrent conditions discussed above do not have the potential to affect the site, and evidence of paleoliquefaction features was not observed, our evaluation indicates that the potential for liquefaction and associated adverse effects within the site is low. The site conditions will also be improved by removal and recompaction of low density near-surface soils, and if evidence for paleoliquefaction is encountered during grading, the use of post-tension slabs. LABORATORY TESTING General Laboratory tests were performed on a representative sample of the onsite earth materials in order to evaluate their physical and engineering characteristics. The test procedures used and results obtained are presented below. Moisture-Density Relations The laboratory maximum dry density and optimum moisture content for two representative site soils was determined according to test method ASTM D-1 557. A maximum dry density of 129.0 pcf at an optimum moisture content of 10.0 percent and 127.0 pcf at an optimum moisture content of 10.0 were determined for two bulk composite samples obtained from the site. Field moisture and density determinations were also performed. The results of these determinations are presented on the Test Pit Logs in Appendix B. Shear Testing Shear testing was performed on a representative, remolded sample of site soil, in general accordance with ASTM Test Method 0-3080, in a Direct Shear Machine of the strain control type. The shear test results are summarized below: Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 Flle:e:wp9\4300\4333a.pge Page 10 GeoSoils, Inc. SAMPLE LOCATION PRIMARY RESIDUAL COHESION FRICTION COHESION FRICTION (PSF) ANGLE (PSF) ANGLE (DEGREES) (DEGREES) TP-2 © 0- 2 feet 108 1 36 ( 41 372 Expansion Potential Expansion testing was performed on representative samples of site soil in accordance with UBC Standard 18-2. The results of expansion testing are presented in the following table. T [_LOCATION T EXPANSION INDEX EXPANSION POTENTIAL TP-1 @7-8feet 2 Very Low TP-2@0-2feet 0 Very Low Corrosion Testing Laboratory test results for soluble sulfates, pH, and corrosion to metals have not been received as of the date of this report. Testing will be presented as an addendum upon receipt of the results. Additional testing of site materials is recommended when proposed grading is complete, to further evaluate the findings. CONCLUSIONS Based upon our site reconnaissance test results, it is our opinion that the subject site appears suitable for the proposed residential development. A preliminary building setback of 1:1 (h:v) from the base of the existing near-vertical natural slope should be maintained. Continued erosion and maintenance in this area will be required. The following recommendations should be additionally incorporated into the construction details. EARTHWORK CONSTRUCTION RECOMMENDATIONS General All grading should conform to the guidelines presented in Appendix Chapter A33 of the UBC, the requirements of the City, and the Grading Guidelines presented in Appendix E, except where specifically superceded in the text of this report. Prior to grading, a GSI Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 F1Ie:e:\wp9\4300\4333a.pgo Page 11 GeoSoils, Inc. 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 GSl. 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, existing structures, and other deleterious material should be removed from the building area prior to the start of construction. Sloping areas to receive fill should be properly benched in accordance with current industry standards of practice and guidelines specified in the UBC. Removals (Unsuitable Surficlal Materials) Due to the relatively loose and dry condition of existing undocumented artificial fill and weathered terrace deposits, these materials should be removed and recompacted in areas proposed for settlement-sensitive structures or areas to receive compacted fill. At this time, removal depths on the order of 1 to 2 feet (weathered terrace deposits) below existing grade on the east portion of the site and at least 13 feet (undocumented artificial fill) on the west portion of the property, should be anticipated; however, locally deeper removals cannot be precluded. Due to the relatively loose, dry, and porous condition of the artificial fill and weathered terrace deposits, these materials should be removed, moisture conditioned, and recompacted and/or processed in place. Removals should be completed below a 1:1 projection down and away from the edge of any settlement-sensitive improvements and/or limits of proposed fill. Once removals are completed, the exposed bottom should be reprocessed and compacted to 90 percent relative compaction. 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. If soil importation is planned, a sample of the soil import should be evaluated by this office prior to importing, in order to assure compatibility with the onsite site soils and the recommendations presented in this report. Import soils for a fill cap should be very low expansive (Expansion Index [El] less than 20). The use of subdrains at the bottom of the fill cap may be necessary, and subsequently recommended based on compatibility with onsite soils and proximity and/or suitability of an outlet. Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 FIIe:e:wp9\4300\4333a.pge Page 12 GeoSoils, Inc. Transitions/Overexcavat ion Cut portions of cut/fill transition pads should be overexcavated a minimum 3 feet below pad grade. Areas with planned fills less than 3 feet should be overexcavated in order to provide a minimum fill thickness of 3 feet, or 2 feet below the foundation, Whichever is greater. Where the ratio of maximum to minimum fill thickness below a given structure exceeds 3:1, overexcavation should be completed to reduce this ratio to 3:1, or less Subdralns In general, and based upon the available data to date, groundwater is not anticipated to be a factor in development of the site. However, due to the nature of the site materials, seepage may be encountered throughout the site, along with seasonal perched water within any drainage areas. Seepage may also be encountered in "daylighted" joint systems within the terrace deposits. Thus, subdrain systems are recommended within shallow groundwater areas. In addition, subdrainage systems for the control of localized groundwater seepage should be anticipated, should such conditions develop during or after grading. Should such conditions develop, this office should be contacted for mitigative recommendations. Local seepage along the contact between the bedrock and overburden materials, or along jointing patterns of-the bedrock, will likely require a subdrain system. Where removals are below the subdrain flowline, the removal materials may be reused as compacted fill provided they are granular, and at a moisture content of at least 2 percent over optimum moisture content (or 1.2 times optimum moisture content, whichever is greater). Slope Considerations and SloDe Design All slopes should be designed and constructed in accordance with the minimum requirements of the County, the recommendations in Appendix E, and the following: Fill slopes should be designed and constructed at a 2:1 (honzontal:vertical [h:v]) gradient, or flatter. Fill slopes should be properly built and compacted to a minimum relative compaction of 90 percent throughout, including the slope surfaces. Guidelines for slope construction are presented in Appendix E. Cut slopes should be designed at gradients of 2:1 and should not exceed 10 feet in height. While stabilization of such slopes is not anticipated, locally adverse geologic conditions (i.e., daylighted joints/fractures or severely weathered bedrock) may be encountered, which may require remedial grading or laying back of the slope to an angle flatter than the adverse geologic condition. Local areas of highly to severely weathered bedrock, or non-cohesive sands, may L, be present. Should these materials be exposed in cut slopes, the potential for long Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 FiIe:e:wp9\4300\4333a.pge Page 13 GeoSoils, Inc. term maintenance or possibly slope failure exists. Evaluation of cut slopes during grading would be necessary in order to identify any areas of severely weathered bedrock or non-cohesive sands. Should any of these materials be exposed during construction, the soils engineer/geologist would assess the magnitude and extent of the materials and their potential effect on long term maintenance or possible slope failures. Recommendations would then be made at the time of the field inspection. I - 4. Cut slopes should be mapped by the project engineering geologist during grading to allow amendments to the recommendations, should exposed conditions warrant alternation of the design or stabilization. 5. Due to the erosional features observed in the near vertical, natural slope, located -' on the north side of the property, a 1:1 (h:v) setback from the base of the slope is recommended for any proposed development in this area. (fl RECOMMENDATIONS - FOUNDATIONS \ 1 PrelimInary Foundation Design In the event that the information concerning the proposed development plans are not correct, or any changes in the design, location, or loading conditions of the proposed structures are made, the conclusions and recommendations contained in this report are for the subject site only and 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 considered minimums and are not meant to supercede design(s) 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. They are considered preliminary recommendations for proposed construction, in consideration of our field investigation, and laboratory testing and engineering analysis. Our review, field work, and recent and previous laboratory testing indicates that onsite soils have a very low expansion potential range (E.l. 0 to 20). Preliminary recommendations for foundation design and construction are presented below. Final foundation recommendations should be provided at the conclusion of grading based on laboratory testing of fill materials exposed at finish grade. Bearing Value 1. The foundation systems should be designed and constructed in accordance with guidelines presented in the latest edition of the UBC. Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 F1Ie:e:\wp9\4300\4333a.pge Page 14 GeoSoils, Inc. 2. An allowable bearing value of 1,500 pounds per square foot (psf) may 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 18 inches deep founded entirely into compacted fill or competent formational material and connected by grade beam or tie beam in at least one direction. This value may be increased by 20 percent for - each additional 12 inches in depth to a maximum value of 2,500 psf. 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. Lateral Pressure• For lateral sliding resistance, a 0.35 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load. Passive earth pressure may be computed as an equivalent fluid having a density of 250 pounds per cubic foot (pcf), with a maximum earth pressure of 2,500 psf. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. Foundation Settlement Foundations systems should be designed to accommodate a worst case differential - settlement of 1 inch in a 40-foot span. Footina Setbacks All footings should maintain a minimum 7-foot horizontal setback from the base of the footing to any descending slope. This distance is measured from the footing face at the bearing elevation. Footings should maintain a minimum horizontal setback of H/3 (H =slope height) from the base of the footing to the descending slope face, and no less than 7 feet nor need to be greater than 40 feet. Footings adjacent to unlined drainage swales should be deepened to a minimum of 6 inches below the invert of the adjacent unlined swale. Footings for structures adjacent to retaining walls should be deepened so as to extend below a 1:1 projection from the heel of the wall. Alternatively, walls may be designed to accommodate structural loads from buildings or appurtenances as described in the Retaining Wall section of this report. Construction The following foundation construction recommendations are presented as a minimum criteria from a soils engineering standpoint. The onsite soils expansion potentials are generally very low (E.l. 0 to 20). Recommendations for very low expansive soil conditions are presented herein. Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad • May 26, 2004 Flle:e:wp9\430O\4333a.pgo Page 15 GeoSoils, Inc. Recommendations by the project's design-structural engineer or architect, which may exceed the soils engineers recommendations, should take precedence over the following minimum requirements. Final foundation design will be provided based on the expansion potential of the near surface soils encountered during grading. Very Low Expansion Potential (E.l. 0 to 20) Exterior and interior footings should be founded at a minimum depth of 12 inches for one-story floor loads, 18 inches for two-story floor loads, and 24 inches for three-story floor loads below the lowest adjacent ground surface. Isolated column and panel pads, should be founded at a minimum depth of 24 inches. All footings should be reinforced with two No. 4 reinforcing bars, one placed near the top and one placed near the bottom of the footing. Footing widths should be as indicated in the UBC (ICBO, 1997); width of 12 inches for one-story loads, 15 inches for two- story loads, and 18 inches for three-story loads. A grade beam, reinforced as above, and at least 12 inches wide should be provided across large (e.g., doorways) entrances. The base of the grade beam should be at the same elevation as the bottom of adjoining footings. Isolated, exterior square footings should be tied within the main foundation in at least one direction with a grade beam. Residential concrete slabs, where moisture condensation is undesirable, should be underlain with a vapor barrier consisting of a minimum of 10 mil polyvinyl chloride or equivalent membrane with all laps sealed. This membrane should be covered above and below with a minimum of 2 inches of sand (total of 4 inches) to aid in uniform curing of the concrete and to protect the membrane from puncture. Residential concrete slabs should be a minimum of 4 inches thick, and should be reinforced with No. 3 reinforcing bar at 18 inches on center in both directions. All slab reinforcement should be supported to ensure placement near the vertical midpoint of the concrete. "Hooking" of reinforcement is not considered an acceptable method of positioning the reinforcement. Residential garage slabs, should be a minimum of 5 inches thick and should be reinforced as above and poured separately from the structural footings and quartered with expansion joints or saw cuts. A positive separation from the footings should be maintained with expansion joint material to permit relative movement. Specific presaturation is required for these soil conditions, GSl recommends that the moisture content of the subgrade soils be equal to, or greater than, optimum moisture content to a depth of 12 inches in the slab areas prior to the placement of visqueen. Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 F1Ie:e:\wp9\43004333a.pge Page 16 GeoSoils, Inc. POST-TENSIONED SLAB SYSTEMS Post-tension foundations are specifically recommended if paleoliquefaction features ("sand P blows," liquefaction craters, sand filled fissures and injection dikes, sand vents, etc.) are - encountered during grading. The recommendations presented below should be followed ., in addition to those contained in the previous sections, as appropriate. The information and recommendations presented below in this section are not meant to supercede design by a registered structural engineer or civil engineer familiar with post-tensioned slab - design. Post-tensioned slabs should be designed using sound engineering practice and be in accordance with local and/or national code requirements. Upon request, GSI can provide additional data/consultation regarding soil parameters as related to post-tensioned I slab design. From a soil expansion/shrinkage standpoint, a common contributing factor to distress of structures using post-tensioned slabs is fluctuation of moisture in soils underlying the i perimeter of the slab, compared to the center, causing a "dishing" or "arching" of the slabs. To mitigate this possibility, a combination of soil presaturation and construction of a '[1 perimeter cut-off wall should be employed. Perimeter cut-off walls should be a minimum of (18 inches deep for medium expansive soils. The cut-off walls may be integrated into the slab design or independent of the slab. The concrete slab should be a minimum of 6 inches thick. Slab underlayment should consist of 4 inches of washed sand with a vapor barrier consisting of 10-mil polyvinyl chloride or equivalent placed mid-depth within the sand. Post-Tensioning Institute Method Post-tensioned slabs should have sufficient stiffness to resist excessive bending due to non-uniform swell and shrinkage of subgrade soils. The differential movement can occur at the corner, edge, or center of the slab. The potential for differential uplift can be evaluated using the 1997 UBC, Section 1816, based on design specifications of the Post-Tensioning Institute. The following table presents suggested minimum coefficients to be used in the Post-Tbnsioning Institute design method. Thornthwaite Moisture Index -20 inches/year Correction Factor for Irrigation 20 inches/year Depth to Constant Soil Suction 7 feet Constant soil Suction (pt) 3.6 Modulus of Subgrade Reaction (pci) 75 Moisture Velocity 0.7 inch/month Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 FIIe:e:\wp9\43004333a.pge Page 17 GeoSoils, Inc. The coefficients are considered minimums and may not be adequate to represent worst case conditions such as adverse drainage and/or improper landscaping and maintenance. The above parameters are applicable provided structures have positive drainage that is maintained away from structures. Therefore, it is important that information regarding drainage, site maintenance, settlements, and effects of expansive soils be passed on to future owners. Based on the above parameters, the following values were obtained from figures or tables of the 1997 UBC Section, 1816. The values may not be appropriate to account for possible differential settlement of the slab due to other factors. If a stiffer slab is desired, higher values of ym may be warranted. :EXPANSION INDEX OF -,. 1SÔILSUBGRAbE'.1 VERY Low;. EXPANSION '__4'' (El 0-20).` Om Center lift 5.0 feet em edge lift 2.5 feet Ym center lift 1.0 inch y edge lift 0.3 inch Deepened footings/edges around the slab perimeter must be used to minimize non-uniform surface moisture migration (from an outside source) beneath the slab. An edge depth of 12 inches should be considered a minimum. The bottom of the deepened footing/edge should be designed to resist tension, using cable or reinforcement per the structural engineer. Other applicable recommendations presented under conventional foundation and the California Foundation Slab Method should be adhered to during the design and construction phase of the project. UTILITIES Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement (and any potentially expansive soil conditions). Due to the potential for differential settlement, air conditioning (NC) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. NC waste waterlines should be drained to a suitable outlet. Family Real Estate Enterprises W.O. 4333-A-SC 4998 Euàalyptus Lane, Carlsbad May 26, 2004 FIIe:e:\wp9\4300\4333a.pge Page 18 GeoSoils, Inc. WALL DESIGN PARAMETERS Conventional Retaining Walls The design parameters provided below assume that either non expansive soils (Class 2 permeable filter material or Class 3 aggregate base) or native materials (up to and including an E.I. of 65) are used to backfill any retaining walls. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the plans. Building walls, below grade, should be water-proofed or damp-proofed, depending on the degree of moisture protection desired. The foundation system for the proposed retaining walls should be designed in accordance with the recommendations presented in this and preceding sections of this report, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches) and should be 24 inches in width. There should be no increase in bearing for footing width. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid pressure (EFP) of 65 pcf, plus any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (21-1) laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 10 feet high. Design parameters for walls less than 3 feet in height may be superceded by City and/or County standard design. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. These do not include other superimposed loading conditions due to traffic, structures, seismic events or adverse geologic conditions. When wall configurations are finalized, the appropriate loading conditions for superimposed loads can be provided upon request. Family Real Estate Enterprises . W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 FiIe:e:\wp9\43004333a.pge Page 19 GeoSoils, Inc. SURFACE SLOPE OF EQUIVALENT EQUIVALENT RETAINED MATERIAL FLUID WEIGHT P.C.F. FLUID WEIGHT P.C.F. (HORIZONTAL:VERTICAL) (SELECT BACKFILL) (NATIVE BACKFILL) Level* 1 35 45 2tol 50 60 * Level backfill behind a retaining wall is defined as compacted earth materials, properly drained, without a slope for a distance of 2H behind the wall. Retaining Wail Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1, 2, and 3, present the back drainage options discussed below. Backdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or ½-inch to 3/4 inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). For low expansive backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the wails and upward at least 1 foot. For native backfill that has up to medium expansion potential, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and confined areas, (panel) drainage behind the wall may be constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an E.I. potential of greater than 65 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than ±100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes in walls higher than 2 feet should not be considered. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with native soil (E.l. 190). Proper surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the back of all retaining structures. The use of a waterstop should be considered for all concrete and masonry joints. [ Wall/Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: a) A minimum of a 2-foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 FIIe:e:\wp9\4300\4333a.pge Page 20 GeoSoils, Inc. Providi 4 iterproofing : 1-Membrane (optior ® Weep H Finished Surfaci DETAILS N.T.S. WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. ROCK: 3/4 to 1-1/2" (inch fts) rock. © FILTER FABRIC: Mlrafi 140N or approved equivalent; place fabric flap behind core. I PIPE: 4" (inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1% gradient to proper outlet point. © WEEP HOLE: Minimum 2" (Inches) diameter placed at 20' (feet) on centers along the wall, and 3" (Inches) [ above finished surface. (No weep holes for basement walls.) TYPICAL RETAINING WALL BACKFILL AND DRAINAGE DETAIL DETAIL I Geotechnical 9 Geologic 9 Environmental Provide 17 iterproofing Membrane (o ® Weep Finished DETAILS N. T . S WATERPROOFING MEMBRANE (optional): Uquid boot or approved equivalent. DRAIN: Mlradrain 6000 or J-drain 200 or equivalent for non-waterproofed walls. MiradraIn 6200 or Jdraln 200 or equivalent for waterproofed walls. FILTER FABRIC: Mlrafi 140N or approved equivalent; place fabric flap behind care. PIPE: 4" (Inches) diameter perforated PVC. schedule 40 or approved alternative with minimum of 1% gradient to proper outlet point. WEEP HOLE: Minimum 2" (inches) diameter placed at 20' (feet) on centers along the wall, and 3" (inches) above finished surface. (No weep holes for basement walls.) RETAINING WALL BACKFILL AND SUBDRAIN DETAIL GEOTEXTILE DRAIN DETAIL 2 Geotechnical • Geologic • Environmental DETAILS N. T:s Native Backfill Provide Surface Drainage - +120 I, ® Weep Hole Finished Surface Slope or Level H/2 7 mm. j(X) Waterroofing Membrane (optional) I or Flatter Pi/ . ®Clean r © Filter Fabrlc Sand Backfill j Roc 'T. Heel Width 1 4 (D WATERPROOFING MEMBRANE (optional): Liquid boot or approved equivalent. © CLEAN SAND BACKFILL: Must have sand dequivalent value of 30 or greater; can be densified by water jetting. © FILTER FABRIC: Mirafl 140N or approved equivalent. ROCK:. 1 cubic foot per linear feet of pipe or 3/4 to 1-1/2" (Inches) rock. PIPE: 4" (inches) diameter perforated PVC. schedule 40 or approved -alternative with minimum of 1% gradient to proper outlet point. WEEP HOLE: Minimum 2° (inches) diameter placed at 20' (feet) on centers along the wail, and 3" (inches) above finished surface. (No weep holes for basement walls.) • RETAINING WALL AND SUBDRAIN DETAIL • I . ' LL CLEAN SAND BACKFIDETAIL 3 I Geotechnical Geologic • Environmental b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints or crack control joints) such that a angular distortion of 1/360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be sealed with a flexible, non-shrink grout. C) Embed the footings entirely into native formational material (i.e., deepened footings). E If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. r TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS L Slope Creep Soils at the site may be expansive and therefore, may become desiccated when allowed to dry. Such soils are susceptible to surficial slope creep, especially with seasonal changes in moisture content Typically in southern California, during the hot and dry summer period, these soils become desiccated and shrink, thereby developing surface cracks. The extent and depth of these shrinkage cracks depend on many factors such as I the nature and expansivity of the soils, temperature and humidity, and extraction of moisture from surface soils by plants and roots. When seasonal rains occur, water percolates into the cracks and fissures, causing slope surfaces to expand, with a corresponding loss in soil density and shear strength near the slope surface. With the passage of time and several moisture cycles, the outer 3 to 5 feet of slope materials experience a very slow, but progressive, outward and downward movement, known as slope creep. For slope heights greater than 10 feet, this creep related soil movement will typically impact all rear yard flatwork and other secondary improvements that are located within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork, etc., and in particular top of slope fences/walls. This influence is normally in the form of detrimental settlement, and tilting of the proposed improvements. The dessication/swelling and creep discussed above continues over the life of the improvements, and generally becomes progressively worse. Accordingly, the developer should provide this information to any homeowners and homeowners association. Top of Slope Walls/Fences Due to the potential for slope creep for slopes higher than about 10 feet, some settlement and tilting of the walls/fence with the corresponding distresses, should be expected. To mitigate the tilting of top of slope walls/fences, we recommend that the walls/fences be constructed on deepened foundations without any consideration for creep forces, where the E.I. of the materials comprising the outer 15 feet of the slope is less than 50, or a Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 F1Ie:e:\wp9\4300\4333a.pge Page 24 GeoSoils, Inc. combination of grade beam and caisson foundations, for expansion indices greater than 50 comprising the slope, with creep forces taken into account. The grade beam should be at a minimum of 12 inches by 12 inches in cross section, supported by drilled caissons, 12 inches minimum in diameter, placed at a maximum spacing of 6 feet on center, and with a minimum embedment length of 7 feet below the bottom of the grade beam. The strength of the concrete and grout should be evaluated by the structural engineer of record. The proper ASTM tests for the concrete and mortar should be provided along with the slump quantities. The concrete used should be appropriate to mitigate sulfate corrosion, as warranted. The design of the grade beam and caissons should be in accordance with the recommendations of the project structural engineer, and include the utilization of the following geotechnical parameters: Creep Zone: 5-foot vertical zone below the slope face and projected upward parallel to the slope face. Creep Load: The creep load projected on the area of the grade beam should be taken as an equivalent fluid approach, having a density of 60 pcf. For the caisson, it. should be taken as a uniform 900 pounds per linear foot of caisson's depth, located above the creep zone. Point of Fixity: Located a distance of 1.5 times the caisson's diameter, below the creep zone. Passive Resistance: Passive earth pressure of 300 psf per foot of depth per foot of caisson diameter, to a maximum value of 4,500 psf may be used to determine caisson depth and spacing, provided that they meet or exceed the minimum requirements stated above. To determine the total lateral resistance, the contribution of the creep prone zone above the point of fixity, to passive resistance, should be disregarded. Allowable Axial Capaci Shaft capacity: 350 psf applied below the point of fixity over the surface area of the shaft. Tip capacity: 4,500 .psf. Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 FiIe:e:\wp9\4300\4333a.pge Page 25 GeoSo ifs, Inc. DRIVEWAY. FLATWORK, AND OTHER IMPROVEMENTS The soil materials on site may be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended that the developer should notify any homeowners or homeowners association of this long-term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points above (or 125 percent of) the soils' optimum moisture content, to a depth of 18 inches below subgrade elevation. If very low expansive soils are present, only optimum moisture content, or greater, is required and specific presoaking .is not warranted. The moisture content of the subgrade should be verified within 72 hours prior to pouring concrete. Concrete slabs should be cast over a non-yielding surface, consisting of a 4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. If very low expansive soils are-present, the rock or gravel or sand may be deleted. The layer or subgrade should be wet-down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and approaches should additionally have a thickened edge (12 inches) adjacent to all landscape areas, to help impede infiltration of landscape water under the slab. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and; b) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each direction. The exterior slabs should be scored or saw cut, ½ to We inches deep, often enough so that no section is greater than 10 feet by 10 feet. For sidewalks or narrow slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 FiIe:e:\wp9\4300\4333a.pge Page 26 GeoSoils, Inc. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Concrete compression strength should be a minimum of 2,500 psi. Driveways, sidewalks, and patio slabs adjacent to the house should be separated from the house with thick expansion joint filler material. In areas directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. Planters and walls should not be tied to the house. B. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. If very low expansion soils are present, footings need only be tied in one direction. Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These segments should be keyed or doweled together. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. Positive site drainage should be maintained at all times. Finish grade on the lots should provide a minimum of 1 to 2 percent fall to the street, as indicated herein. It should be kept in mind that drainage reversals could occur, including post-construction settlement, if relatively flat yard drainage gradients are not periodically maintained by the homeowner or homeowners association. Air conditioning (A/C) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. NC waste water lines should be drained to a suitable non-erosive outlej. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed. Finishing and curing practices should be performed per the Portland Cement Association Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of soils, and fertilizers used on site. Family Real Estate Enterprises S W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 FIIe:e:\wp9\4300\4333a.pge Page 27 GeoSoils, Inc. DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors of safety for gross or surficial stability and constructed in general accordance with the design specifications should be expected to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out-of-slope direction, after grading. This post-constriction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Slope creep is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occur throughout the life of the slope, and is anticipated to potentially affect improvements or structures (i.e., separations and/or cracking), placed near the top-of-slope, up to a maximum distance of approximately 15 feet from the top-of-slope, depending on the slope height. This movement generally results in rotation and differential settlement of improvements located within the creep zone. LFE occurs due to deep wetting from irrigaticrn and rainfall on slopes comprised of expansive materials. Although some movement should be expected, long-term movement from this source may be minimized, but not eliminated, by placing the fill throughout the slope region, wet of the fill's optimum moisture content. It is generally not practical to attempt to eliminate the effects of either slope creep or LFE. Suitable mitigative measures to reduce the potential of lateral deformation typically include: setback of improvements from the slope faces (per the 1997 UBC and/or California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to each homeowner and/or any homeowners association. Slope Maintenance and Planting Water has been shown. to weaken the inherent strength of all earth materials. Slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Over-watering should be avoided as it can adversely affect site improvements, and cause perched groundwater conditions. Graded slopes constructed utilizing onsité materials would be erosive. Eroded debris may be minimized and surhcial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face of fill slopes would tend to minimize short-term erosion until vegetation is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of surviving the prevailing climate. Jute-type matting or other fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, mold, etc., to Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 F1Ie:e:wp9\4300\4333a.pge Page 28 GeoSoils, Inc. develop. A rodent control program to prevent burrowing should be implemented. Irrigation of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to each homeowner. Over-steepening of slopes should be avoided during building construction activities and landscaping. Drainage Adequate lot surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations, hardscape, and slopes. Surface drainage should be - sufficient to prevent ponding of water anywhere on a lot, and especially near structures and tops of slopes. Lot surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should be taken that - future landscaping or construction activities do not create adverse drainage conditions. Positive site drainage within lots and common areas should be provided and maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water Should be directed away from foundations and not allowed to pond and/or seep into the ground. In general, the area within 5 feet around .a structure should slope away from the structure. We recommend that unpaved lawn and landscape areas have a minimum gradient of 1 percent sloping away from structures, and whenever possible, should be above adjacent paved areas. Consideration should be given to avoiding construction of planters adjacent to structures (buildings, pools, spas, etc.). Pad drainage should be directed toward the street or other approved area(s). Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means may be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall, and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. Erosion Control Cut and fill slopes will be subject to surflcial erosion during and after grading. Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over-watering the landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open-bottom planters adjacent to proposed structures be eliminated for a minimum distance of 10 feet. As an alternative, closed-bottom type planters could be utilized. An outlet placed in the bottom of the Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 FiIe:e:\wp9\43O04333&pge Page 29 GeoSoils, Inc. planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. if planters are constructed adjacent to structures, the sides and bottom of the planter should be provided with a moisture barrier to prevent penetration of irrigation water into the subgrade. Provisions should be made to drain the excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters. Graded slope areas should be planted with drought resistant vegetation. Consideration should be given to the type of vegetation chosen and their potential effect upon surface improvements (i.e., some trees will have an effect on concrete flatwork with their extensive root systems). 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 minimum relative compaction. Gutters and Downspouts As previously discussed in the drainage section, the installation of gutters and downspouts should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures If utilized, the downspouts should be drained into PVC collector, pipes or non-erosive devices that will carry the water away from the house. Downspouts and gutters are not a requirement; however, from a geotechnical viewpoint, provided that positive drainage is incorporated into project design (as discussed previously). Subsurface and Surface Water 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 zones of contrasting permeabilities may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. Site Improvements Recommendations for exterior concrete flatwork design and construction can be provided upon request. If in the future, any additional improvements (e.g., pools, spas, etc.) 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 fill placement, grading of the site, or trench backfllling after rough grading has been completed. This includes any grading, utility trench, and retaining wall backfllIs. I - Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad May 26, 2004 F1Ie:e:\wp943OO\4333a.pge Page 30 GeoSoils, Inc. Tile Flooring Tile flooring can crack, reflecting cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should consider additional steel reinforcement for concrete slabs-on-grade where tile will be placed. The tile installer should consider installation methods that reduce possible cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs on grade. Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backfllling after rough grading has been completed. This includes completion of grading in the street and parking areas and utility trench and retaining wall backfills. Footing Trench Excavation All footing excavations should be observed by a representative of this firm subsequent to trenching and Drior to concrete form and reinforcement placement. The purpose of the observations is to verify that the excavations are made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of the subgrade materials would be recommended at that time. Footing trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of 90 percent, if not removed from the site. Trenching Considering the nature of the onsite soils, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls at the angle of repose (typically 25 to 45 degrees) may be necessary and should be anticipated. All excavations should be observed by one of our representatives and minimally conform to CAL-OSHA and local safety codes. Utility Trench Backfill All interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent of the laboratory standard. As an alternative for shallow (12-inch to 18-inch) under-slab trenches, sand having a. sand equivalent value of 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to verify the desired results. Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad S May 26, 2004 F1I9:e:\wp9\4300\4333a.pge Page 31 GeoSoils, Inc. Exterior trenches adjacent to, and within areas extending below a 1:1 plane projected from the outside bottom edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to verify the desired results. All trench excavations should conform to CAL-OSHA and local safety codes. F . Utilities crossing grade beams, perimeter beams, or footings should either pass below the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations of the -' structural engineer. Li SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING / We recommend that observation and/or testing be performed by GSI at each of the r following construction stages: During grading/recertification. - During significant excavation (i.e., higher than 4 feet). During placement of subdrains, toe drains, or other subdrainage devices, prior to - placing fill and/or backfill. After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. Prior to pouring any slabs or flatwork, after presoaking/presaturation of building pads and other fiatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor barriers (i.e., visqueen, etc.). During retaining wall subdrain installation, prior to backfill placement. During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. During slope construction/repair. Family Real Estate Enterprises W.O. 4333-A-SC - 4998 Eucalyptus Lane, Carlsbad May 26, 2004 FiIe:e:wp9\43004333a.pge Page 32 - GeoSoils, Inc. When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed. I • A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and, clear F documentation of site work, and/or to comply with code requirements. OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. In order to mitigate potential distress, the, foundation and/or improvement's designer should confirm to GSI and the governing agency, in writing, that the proposed foundations and/or improvements can tolerate the amount of differential settlement and/or expansion characteristics and design criteria specified herein. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedroàk materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions 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 or testing performed by others, or their inaction; or work performed when GSI is not requested to be onsite, to evaluate if our recommendations have been properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this project. I Family Real Estate Enterprises 4998 Eucalyptus Lane, Carlsbad F11e:e:wp9\430o\4333a.pge W.O. 4333-A-SC May 26, 2004 Page 33 GeoSoils, Inc. APPENDIX A REFERENCES APPENDIX A REFERENCES Blake, T.F., 2000a, EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3-0 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 3-0 faults as earthquake sources; Windows 95/98 version. Bozorgnia, Y., Campbell, K.W;, and Niazi, M., 1999, Vertical ground motion: Characteristics, relationship with horizontal component, and building-code implications; Proceedings of the SM1P99 seminar on utilization of strong-motion data, September, 15, Oakland, pp. 23-49. Campbell, K.W. and Bozorgnia, V. 1997, Attenuation relations for soft rock conditions; in EQFAULT, A computer program for the estimation of peak horizontal acceleration from 3-D fault sources; Windows 95/98 version, Blake, 2000a. 1994, Near-source attenuation of peak horizontal acceleration from worldwide accelrograms recorded from 1957 to 1993; Proceedings, Fifth U.S. National Conference on Earthquake Engineering, Volume Ill, Earthquake Engineering Research Institute, pp 292-293. Geocon, Inc., 1999, Rancho Real (Carlsbad Tract No. 90-13) Carlsbad, California, report of testing and observation services during site gradingi project number 06171-42-01, dated January 27. Hart, E.W. and Bryant, W.A. 1997, Fault-rupture hazard zones in California, Alquist-Priolo earthquake fault zoning act with Index to Earthquake Fault Maps; California Division of Mines and Geology Special Publication 42. International Conference of Building Officials, 1997, Uniform building code: Whittier, California, vol. 1, 2, and 3. 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 eds., Johnson, J.A., Campbell, K.W., and Blake, T.F.: AEG Short Course, Seismic Hazard Analysis, June 18, 1994. GeoSoils, Inc. 1982b, Prediction of earthquake response spectra, U.S. Geological Survey Open- File Report 82-977, 16p. Obermeier, S.F., 1996, Using liquefaction-induced features for paleoseismic analysis, Chapter 7, in Paleoseismology, McCalpin, J.P., ed., Academic Press, Inc., San Diego, California. Parker, Claude B., Geotechnical Consultant, Preliminary geotechnical report for proposed residential structure, 5480 Carlsbad Boulevard, Carlsbad, County of San Diego, - California, Job no. 82-471 P, dated August 22, 1982. Sadigh, K., Chang, C.-Y., Egan, J.A., Makdisi, F., and Youngs, R.R., 1997, Attenuation relations for shallow crustal earthquakes based on California strong motion data, Seismological Research Letters, Vol. 68, No. 1, pp. 180-189. Sadigh, K., Egan, J., and Youngs, A., 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. Treiman, J.A., 1993, The Rose Canyon fault zone, southern California: California Division of Mines and Geology, Open File report OFR 93-02. 1991, Rose Canyon fault zone, San Diego county, California: California division of Mines and Geology, fault Evaluation Report FER-216, July 10, revised January 25, 1991, 14p. 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 quadranles, San Diego County, California: unpublished masters thesis, University of California, Riverside. Family Real Estate Enterprises Appendix A - F11e:e:\wp9\4300\4333a.pge Page 2 GeoSoils, Inc. APPENDIX B TEST PIT LOGS - :dW Family Real Estate 4998 Eucalyptus Lane May 13, 2004 LOG OF EXPLORATORY TEST PITS ;•.:. ' ,;..: : -f SAMPLES r7. FIELDtDRY .. :: 7: - . -• PIT NO..,DEPTH GROUP DEPTH MOISTURE DENSITY DESCRIPTION TP-1 0- 13 SM 7-8 BULK ARTIFICIAL FILL- UNDOCUMENTED: SILTY SAND, brown, dry, loose; abundant trash consisting of concrete, metal bar, large tree roots, at west end of trench a large piece of concrete - former curb and gutter appearance, metal pieces, asphalt. @11' Former asphalt road, concrete, old metal water pipe. • Total Depth = 13' No Groundwater/Caving Encountered Backfilled 5-13-2004 FTP -2 0 2 0-2 SM 0-2 CHUNK 3.6 110.8 Sm TERRACE DEPOSITS: SILTY SANDSTONE red brown, damp, dense. Total Depth = 2' No Groundwater/Caving Encountered Backfilled 5-13-04 PLATE B-I F APPENDIX C SITE PHOTOGRAPHS '. 1 2. ft.. I .41 J Conu u tree limbs and roots in undocumented artificial fill in Test Pit TP-1. Sinkhole in undocumented artificial fill. kDA SITE PHOTOGRAPHS Plate C-i Geotechnical Coastal Geologic. Environmental -' Sinkhole in undocumented artificial fill as seen on east side of fence. I * Ij •. ;Ar. .. , I•. &ç r. : :... Exit of sinkhole from Photo .3 irom the west side of fence. SITE PHOTOGRAPHS Plate C-2 5/04 IW.O. NO. 4333-A-SC Geotechnical Coastal Geologic• Environmental Lj I -. :. Erosion of natural slope (undermining and talus) on north side of property. .•_'*._ ,. ;_ •:. I.e. •l.• .. . z ; • ,.l. Erosion 01 slope (bedding plane crack and semi-vertical cracks) on north side of property. Geotechnical Coastal Geologic. Environmental 61 N. APPENDIX D EQFAULT, EQSEARCH, AND FRISKSP EARTHQUAKE RECURRENCE CURVE Eucalyptus 100 10 L- m a) >- z (1) C a) > w 0 .0 E z 001 I 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Magnitude (M) W.O. 4333-A-SC Plate D-1 -U CAMP. & BOZ. (1997 Rev.) SR I 100000000 10000000 1000000 100000 10000 itolols] IOIO 0.00 0.25 0.50 0.75 1.00 1.25 1.50 Acceleration (q) L 100 I 10 Ef PROBABILITY OF EXCEEDANCE CAMP. & BOZ. (1997 Rev.) SR 1 1.1 IAI 25yrs 50yrs 0.00 0.25 0.50 0.75 1.00 1.25 1.50 Acceleration (q) i W.O. 4333ASC Plate D-3 APPENDIX E GENERAL EARTHWORK AND GRADING GUIDELINES GENERAL EARTHWORK AND GRADING GUIDELINES General These guidelines present general procedures and requirements for earthwork and grading II as shown on the approved grading plans, including preparation of areas to filled, I i placement of fill, installation of subdrains and excavations. The recommendations 01 contained in the geotechnical report are part of the earthwork and grading guidelines and 1A pi would supercede 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 contractors's 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 0-1557-78. Random field compaction tests should be performed in accordance with test method ASTM designation 0-1556-82, D-2937 or 0-2922 and 0-3017, at intervals of approximately 2 feet of fill height or every 100 cubic yards of fill placed. These criteria GeoSoils, Inc. 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. I 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 contractors 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 I work until conditions are satisfactory. J 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, c011uvium, 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, pipelines, 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 Family Real Estate Enterprises Appendix E F11e:e:\wp9\4300\4333apge Page 2 GeoSoils, Inc. 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 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 1/2 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 of fill. 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 Family Real Estate Enterprises Appendix E File:e:\wp9\4300\4333a.pge Page 3 GeoSoils, Inc. 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 characteristics may be designated by the consultant as unsuitable And may require blending with other soils to serve as a satisfactory fill material. I Fill materials derived from benching operations should be dispersed throughout the fill i 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 I fl 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 betaken 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 10 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, 0-1557-78, or as otherwise recommended by the soil engineer. I 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 I compaction. Family Real Estate Enterprises Appendix E Fi1e:e:\wp9\4300\4333a.pge Page 4 GeoSoils, Inc. 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 r 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. Afinal 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 10 feet of each lift of fill by undertaking the following: 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 1 extend out over the slope to provide adequate compaction to the face of the slope. Loose fill should not be spilled out over the face of the slope as each lift is 1 compacted. Any loose fill spilled over a previously completed slope face should be J trimmed off or be subject to re-rolling. it 1 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. . 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. Family Real Estate Enterprises Appendix E FIIe:e:\wp9\4300\4333a.pge. Page 5 GeoSoils, Inc. 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 I. 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 reèorded 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. - Family Real Estate Enterprises Appendix E FUe:e:\wp9\4300\4333a.pge Page 6 GeoSoils, Inc. 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. Family Real Estate Enterprises Appendix E FiIe:e:\wp94300\4333a.pge Page 6 GeoSoils, Inc. 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. I 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. [1 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 I completion of grading. n . JOB SAFETY General J 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, J 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 i be maintained. In an effort to minimize risks associated with geotechnical testing and observation, the following precautions are to be implemented for the safety of field 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. 1 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.. Family Real Estate Enterprises Appendix E F11e:e:\wp9\4300\4333a.pge Page 7 GeoSoils, Inc. 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 contractors 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 personnel of all changes to haul roads, cut and fill 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 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. Family Real Estate Enterprises Appendix E FuIe:e:\wp9\43004333a.pge Page 8 GeoSoils, Inc. 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. I Our personnel are directed not to enter any excavation or vertical cut which: 1) is 5 feet or I 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 down" 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 1J] reprocessing and/or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or r 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. Family Real Estate Enterprises • Appendix E F1Ie:e:\wp9\4300\4333a.pge Page 9 GeoSoils, Inc. TYPICAL STABILiZATION / BUTTRESSFILL DETAIL OUTLETS TO BE SPACED AT 1000 MAXIMUM INTERVALS, AND SHALL EXTEND / 12 BEYOND THE FACE OF SLOPE AT TIME OF. ROUGH GRADING COMPLETION. / BLANKET FILL IF RECOMMENDED DESIGN FINISH SLOPE L S MINIMUM 2.1. I BY THE SOIL ENGINEER ILl PIII'UPILIM 25' MAXIM UM.L (W7 'r - - - - - 15 TYPICAL 1-2' CLEAR -u I > H m m 9' TYPICAL BENCHING UTTRESS OR SIDEHILL LOIAMETER NON-PERFORATED OUTLET PIPE AND BACKDRAIN (SEE ALTERNATIVES) BEDROCK TOE HEELI J 3'MINIMUM KEY DEPTH Y/A\W/1II VA' V/4 I IW/4\ W15' MINIMUM OR H12 l. MINIMUM PIPE 20 MINIMUM 4 MINIMUM PIPE 21 7D_ iIi IJ 2" MINIMUM I- m C) I 01 TYPICAL STABILIZATION I BUTTRESS SUBORAIN DETAIL FILTER MATERIAL MINIMUM OF FIVE F13/LINEAR Ft OF PIPF OR FOUR Ft3 /LINEAR Ft OF PIPE WHEN PLACED IN SQUARE CUT TRENCH. ALTERNATIVE IN LIEU OF FILTER MATERIAL: GRAVEL MAY B ElICASED IN APPROVED FILTER FABRIC. FILTER FABRIC SHALL BE MIRAFI 140 OR EQUIVALENT. FILTER FABRIC SHALL BE LAPPED A MINIMUM OF 120 ON ALL JOINTS. MINIMUM 4 DIAMETER PIPE: ABS-ASTM 0-2751. SOR 35 OR ASTM 0-1527 SCHEDULE 40 PVC-ASTM 0-3034, SOR 35 OR ASTM 0-1785 SCHEDULE 40 WITH A CRUSHING STRENGTH OF 1.000 POUNDS MINIMUM, AND A MINIMUM OF 8 UNIFORMLY SPACED PERFORATIONS PER FOOT OF PIPE INSTALLED WITH PERFORATIONS OF BOTTOM OF PIPE. PROVIDE CAP AT UPSTREAM END OF PIPE. SLOPE AT 2% TO OUTLET PIPE. OUTLET PIPE TO BE CONNECTED TO SUBORAIN PIPE WITH TEE OR ELBOW. NOTE: 1. TRENCH FOR OUTLET PIPES TO BE BACKFILLED WITH ON-SITE SOIL. 2. BACKDRAINS AND LATERAL DRAINS SHALL BE LOCATED AT ELEVATION OF EVERY BENCH DRAIN. FIRST DRAIN LOCATED AT ELEVATION JUST ABOVE LOWER LOT GRADE. ADDITIONAL DRAINS MAY BE REQUIRED AT THE DISCRETION OF THE SOILS • ENGINEER AND/OR ENGINEERING GEOLOGIST. FILTER MATERIAL SHALL BE OF THE FOLLOWING SPECIFICATION OR AN APPROVED EQUIVALENT: SIEVE SIZE PERCENT PASSING 1 INCH 100 3/1. INCH 90-100 3/8 INCH 40-100 NO. 1. 25-40 NO. 8 18-33 NO. 30 5-15 NO. 50 0-7 NO. 200 0-3 GRAVEL SHALL BE OF THE FOLLOWING SPECIFICATION OR AN APPROVED EQUIVALENT: SIEVE SIZE PERCENT PASSING 11/2 INCH.. 100 NO.4 50 NO. 200 8 I SAND EQUIVALENT: MINIMUM OF 51 cotwqllo. IV MINIMUM lop -'" BENCH WIDTH MAY VARY ][3'._________ - ___ MINIMUM 14 NOTE: 1. WHERE THE NATURAL SLOPE APPROACHES OR EXCEEDS THE 1'MINIMUM KEY WIOT I DESIGN SLOPE RATIO, SPECIAL RECOMMENDATIONS WOULD BE 2'X 3' MINIMUM KEY DEPTH PROVIDED BY THE SOILS ENGINEER. / 2. THE NEED FOR AND DISPOSITION OF DRAINS WOULD BE DETERMINED 2MINIMUM IN BEDROCK OR BY THE SOILS ENGINEER BASED UPON EXPOSED CONDITIONS. APPROVED MATERIAL -U I- -1 m m G) NATURAL SLOPE TO BE RESTORED WITH COMPACTED FILL DACKCUT VARIES 00, lo~l FILL OVER NATURAL DETAIL SIDEHILL FILL COMPACTED FILL PROPOSED GRADE MAINTAIN MINIMUM 15 WIDTH 0'0TOE OF SLOP AS SHOWN ON GRADING PLAN SLO 19 SLOPE TOBENCH/BACKCUT PROVIDE A i:i MINIMUM PROJECTION FROM DESIGN TOE OF SLOPE TO TOE OF KEY AS SHOWN ON AS BUILT. r.i FILL OVER CUT DETAIL CUT/FILL CONTACT AS SHOWN ON GRADING PLAN AS SHOWN ON AS- BUILT H ORIGINAL TOPOGRAPHY -- CUT SLOPE MAINTAIN MINIMUM .15' FILL SECTION FROM BACKCUT TO FACE OF FINISH SLOPE I PROPOSED GRADE BENCH WIDTH MAY VARY LOWEST BENCH WI01 15' MINIMUM OR H/2 BEDROCK OR APPROVED MATERIAL -U NOTE; THE CUT PORTION OF THE SLOPE SHOULD BE EXCAVATED AND EVALUATED BY THE SOILS ENGINEER AND/OR ENGINEERING -•1 GEOLOGIST PRIOR TO CONSTRUCTING THE FILL PORTION. m m C) I - - - STABILIZATION FILL FOR UNSTABLE MATERIAL EXPOSED IN PORTION OF CUT SLOP - SLOPE REMOVE: UNSTABLE MATERIAL 'POSED FINISHED GRADE TURL UNWEATHERED BEDROCK 15' HINIMUM I-.--P) OR APPROVED MATERIAL H2 REMOVE: UNSTABLE H1 MATERIAL COMPACTED STABILIZATION FILL -0------ 1' MINIMUM TILTED BACK " I / IF RECOMMENDED BY THE SOILS ENGINEER AND/OR ENGINEERING - GEOLOGIST. THE REMAINING CUT PORTION OF THE SLOPE MAY REQUIRE REMOVAL AND REPLACEMENT WITH COMPACTED FILL > -I m NOTE: 1. SUBDRAINS ARE NOT REQUIRED UNLESS SPECIFIED BY SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST, (TI 2. OWT SHALL BE EQUIPMENT WIDTH (15') FOR SLOPE HEIGHTS LESS THAN 25 FEET. FOR SLOPES GREATER' THAN. 25 FEET W SHALL BE DETERMINED BY THE PROJECT SOILS ENGINEER AND /OR ENGINEERING CO GEOLOGIST. AT NO TIME SHALL W BE LESS THAN H/2. - J SKIN FILL OF NATURAL OR OUND ORIGINAL SLOPE -U m C) I (D 15' MINIMUM TO BE MINTAINED FROM PROPOSED FINISH SLOPE FACE TO BACKCUT NISH GRADE J3 MINIMUM PROPOSED FINISH SLOPE BEDROCK OR APPROVED MATERIAL ,7 21MINIMUM '11iI KEY DEPTH ___ ____________________ 36 MINIMUM KEY DEPTH I ANIMUM KEY NOTE: I. THE NEED AND DISPOSITION OF ORAINS WILL BE DETERMINED! BY THE SOILS ENGINEER AND / O R ENGINEERING GEOLOGIST BASED ON FIELD CONDITIONS. 2. PAD OVEREXCAVATION AND RECOMPACTION SHOULD BE PERFORMED IF DETERMINED TO BE NECESSARY BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST. m G) DAYLIGHT CUT LOT DETAIL RECONSTRUCT COMPACTED FILL SLOPE AT 2:1 OR FLATTER (MAY INCREASE OR DECREASE PAD AREAL - OVEREXCAVATE AND RECOMPACT REPLACEMENT FILL AVOID AND/OR CLEAN UP SPILLAGE OF MATERIALS ON THE NATURAL SLOPE NATURAL GRADE 0' -.".-.. -. UrUStU IINIM W(AUt MINIMUM BLANKET FILL C. - 2' MINIMUM %ORA KEY DEPTH . BEDROCK OR APPROVED MATERIAL TYPICAL BENCHING NOTE: 1. SUBORAIN AND KEY WIDTH REQUIREMENTS WILL BE DETERMINED BASED ON EXPOSED SUBSURFACE CONDITIONS AND THICKNESS OF OVERBURDEN. 2. PAD OVER EXCAVATION AND RECOMPACTION SHOULD BE PERFORMED IF DETERMINED NECESSARY BY THIJ SOILS ENGINEER ANDIOR THE ENGINEERING GEOLOGIST. TRANSITION LOT DETAIL CUT LOT (MATERIAL TYPE TRANSITION) NATURAL GRADE I;. . 5M1 PAD GRADE ________ OVER EXCAVATE AND RECOMPACT I COMPACTED FILL 34 MINIMUM * UNWEA IALSENHING 111 ERED BEDROCK OR APPROVED. MATERIAL I.. P CUT-FILL LOT (DAYUGHT TRANSITION) 1•: 3. NATURAL GRADE ." PAD _GRAIIE -. . __MUM R OIL AND ECOMPACT COMPACTED FILL Aw MINIMUMS UNWEATHERED BEDROCK OR APPROVED MATERIAL TYPICAL BENCHING NOTE: DEEPER OVEREXCAVATION MAY BE RECOMMENDED BY THE SOILS ENGINEER AND/OR ENGINEERING GEOLOGIST IN STEEP CUT-FILL TRANSITION AREAS. PLATE EG-11 TEST PIT SAFETY DIAGRAM SPOIL PILE SIDE VIEW PIT.-.-.- ( NOT TO SCALE ) TOP VEW 100 FEE 50FEi 50 FEET FUG PILE FLAG - APPROXIMATE ENTER OFTESTPIT (NOT TO SCALE ) I AT RECIEWIED APR 25 2006 ENGINEERING DEPARTMENT secnei Ii. IluLlin taw I( fe 0 —/ 760-632-2230 p.1 Geotechnical Geologic. Environmental 5741 Palmer Way • Carlsbad, California 92008 9 (760) 438-3155 • FAX (760) 931-0915 June 9, 2004 W.O. 4333-A-SC Family Real Estate Enterprises 560 Highway 101, Suite 1 Encinitas, California 92024. Attention: Ms. Rachel D. Muffin Subject: Soil Corrosivity Results, APN 208-040-05-00, 4996 Eucaly p t u s L a n e , C i t y o f Carlsbad, San Diego County, California References: .1. "Preliminary Geotechnical Evaluation, APN 208-040-05-00,4998 Eucalyptus Lane, City of Carlsbad, San Diego CoUnty, California," W.0.4333-A-SC, dated May 26, 2004, by GeoSoils, Inc. 2. "Uniform Building Code," Whittier, California, Vol. 1, 2, and 3, dated 1997, by International Conference of Building Officials. Dear Ms. Mullin: As discussed in Reference No. 1, GeoSoils, Inc. ( G S l ) c o n d u c t e d s a m p l i n g o f representative soils on the subject site for corrosivity . L a b o r a t o r y t e s t r e s u l t s w e r e completed by M.J. Schiff (consulting corrosion engineers). Unless specifically su p e r c e d e d herein, the conclusions and recommendations contained in t h e r e f e r e n c e d r e p o r t b y G S l remain pertinent and applicable, and should be appropriatel y i m p l e m e n t e d d u r i n g d e s i g n and construction. SUMMARY Atypical sample of the site materials was analyzed for cor r o s i o n / a c i d i t y p o t e n t i a l ( a t t a c h e d as Figure 1, following the text of this letter). The testing incl u d e d d e t e r m i n a t i o n o f s o l u b l e sulfates, pH, and saturated resistivity. Results are as follows: s i t e s o i l s a r e g e n e r a l l y n e u t r a l (pH of 7.3), are severely corrosive to metals (i.e., 680 oh m s - c m ) , a n d h a v e a n e g l i g i b l e potential for sulfate exposure to con&ete (i.e., 0.03 sol u b l e s u l f a t e p e r c e n t b y w e i g h t i n soil). Alternative methods and additional comments reg a r d i n g f o u n d a t i o n s , p i p i n g , e t c . , should be obtained from a qualified corrosion engineer. 7 .cneL U. Mulliti 760-632-2230 p.2 We appreciate the opportunity to be of further service. i f y o u s h o u l d h a v e a n y q u e s t i o n s , please do not hesitate to call our office. Respectfully submitt çD G0• FR'O0 GeoFjoils, Inc. [ ? NO. 1340 COMM J hn P. Franklin O c David W. Skelly gineering Geologist, CE 340 Civil Engineer, ACE 4 DG/JPF/DWS/jk Attachment: Figure 1 - Corrosion Test Results Distribution: (4) Addressee Family Real Estate Enterprises W.O. 4333-A-SC 4998 Eucalyptus Lane, Carlsbad June 9, 2004 File:e:\wp943OO4333a.scr Page 2 GeoSoils, Inc. -. .. r Wachel D. Mullin 760-632-2230 P.3 M. J. Schiff & Associiites, Inc. Cirnsulthsg Cnrron Erigrneerr -Since 1959 - Pluuie: 6-0967F.: (9019),626-1316 31 W. Basdinc Road E-mail lah®mjsthifftom Claremont, C4 9) 7JJ webcae: mj3c1s4ff corn Table I - Laboratory Tests on Soil Samples Family Rea Estalc Your #4333-A-NC MJS&A #.94-0739LA1l .26-May-04 Sample TP-2 --.'-:-•:• Resistivity Unit as.rcccived ohm-cm 20000 saturated ohm-cm 650 pH 7.3 EIectrca* Conductivity mSlcm 032 Chemical Analyses Catiuus calcium C? nigkg 64 magnesium Mf mplcg 19 sodium Na mg1k 264 Anion,-; carbonate C032 ivglcg 'NI) bicarbonate CO mg/kg 104 thloride Cf ing/kg 330 suWate SO, mglkg 254 Other Tests anvuonium NH, MG&I na nitrate NO'• mg/kg 981 sulfide S2.quil na Edax my as • , .- ..Ti -. -•...'.: QI Electrical conductivity in niillisiemcm/cm and chemical analysis wcrc made Qft5 1:5 soil-to-water extract. mg/kg = milligrams per kilogram (parts per million) of dry soil. Redox oxidation-reduction potential in millivolts ND not detected no not analyzed Figure 1 Page 1 of I V 4 SOIL & TESTIVC, INC 4lI I to,.) - S P H 0 N E I P.O. Box 600627 (619)280-4321 San Diego, CA 92160-0627 TOLL -FREE I (877) 215-4321 6280 Riverdale Street FAX I San Diego, CA 92120 (619) 280-4717 I www.scst.com SCS&T No. 0411308 Report No. 1 October 28, 2004 Ms. Rachel Mullin Family Real Estate Enterprises, LLC 560 North Coast Highway 1Q1, Suite 1 Encinitas, California 92024 Subject: SLOPE EVALUATION EUCALYPTUS SUBDIVISION EL CAMINO REAL AND CRESTVIEW DRIVE CARLSBAD, CALIFORNIA Dear Ms. Mullin: In accordance with your request, we have performed an evaluation of the oversteepened cut slope at the subject site. Our findings and conclusions are presented herein. SCOPE OF WORK• Our evaluation was performed in general accordance with our Proposal No. 04S430, dated October 4, 2004. The scope of work consisted of a visual reconnaissance, development of a cross-section, logging of the slope face, obtaining representative soil samples, laboratory testing, engineering analysis, and preparation of this report. We have also reviewed a preliminary geotechnical evaluation report for the subject site prepared by Geosoils, Inc., dated May 26, 2004, as well as an unsigned site plan and an undated copy of a review letter by the City of Carlsbad. SITE AND SOIL DESCRIPTION The subject site is comprised of four adjacent lots located south of El Camino Real, west of Crestview Drive and north of Eucalyptus Lane in Carlsbad, California. The no-rthwestern lot is currently occupied by a single-family residence. Current plans call for development of the remaining three lots with single-family residences. A steep slope presumably cut during the construction of El Carnino Real is present near the northern boundary of the site, south of the El Camino Real right-of-way. The slope has a maximum height of about 30 feet, with inclinations generally ranging from about 1:1 (horizontàl:vertical) to near vertical. A free standing masonry block wall is located near the top of the slope. - Family Real Estate Enterprises, LLC October28, 2004 Eucalyptus Subdivision SCS&T No. 0411308-1 Page 2 The approximate configuration of the subject slope is depicted on the attached cross-section (see Plate No. 1). The cross-section location is in line with the northeastern corner of the existing masonry block wall.. The cross-section generally represents the "worst-case scenario" with respect to slope height and steepness. The slope configuration to the east and west from the cross-section location generally decreases in overall steepness and/or height. The slope configuration shown is based upon rough hind level .and tape measurements, and should be considered accurate only to the degree implied by those methods. The slope at the location evaluated has a height of about 30 feet and an overall inclination of about 0.5:1. The slope is comprised of terrace deposits consisting mainly of pale orange to light gray, dry to humid, medium dense to dense, moderately cemented, very fine to fine, silty sandstone. The lower portion of the slope is covered with talus. Tension cracks were noted on the steeper portions of the slope, both at the cross-section location and in the adjacent slope area to the west. The existing residence is located about 45 feet from the top of the slope at the cross-section location. SLOPE STABILITY ANALYSES Slope stability analyses were performed for the subject slope using Janbu's simplified method. Our analyses indicate a factor of safety with respect to slope failure of about 0.8 for the existing slope. This is less than the minimum factor of safety of 1.5 generally required by current standards of practice. Our analyses further indicate that the slope would possess a factor of safety greater than 1.5 if it were laid back at an inclination of 1.5:1 or flatter. Slope stability calculations are presented on Plate No. 2. Laboratory test results (direct shear and in-place density) are presented on Plate No. 3. The calculated factor of safety for the existing slope (0.8) is less than 1.0, which indicates that the slope should not be standing at its current configuration. Since the slope has been standing for some time without experiencing gross failure, it is likely that the strength parameters derived from our direct shear test (see Plate No. 3) are overly conservative, and that the existing slope actually has a factor of safety slightly greater than 1.0. This also suggests that the actual factors of safety for proposed 1.5:1 or 2:1 inclinations would actually be greater than the values shown on Plate No. 2. CONCLUSIONS The most cost-effective means of achieving an adequate factor of safety (1.5 or greater) for the subject slope would be to lay the slope back to an inclination of 1.5:1 or 2:1. The utilization of a 1.5:1 inclination would minimize the loss of rear yard area for the existing residence and proposed northeastern residence. However, 1.5:1 slopes tend to be more susceptible to erosion SC ST F4mily Real Estate Enteiprises, LLC October 28, 2004 Eucalyptus Subdivision SCS&T No. 0411308-1 Page 3 than 2:1 slopes, and erosion protection devices such as jute matting may be required. A 2:1 inclination would reduce the erosion potential of the slope, but would result in a greater loss of yard space. Regardless of the Slope inclination, suitable vegetative cover should be provided on the slope face as soon as possible after construction, and drainage in the area along the top of the slope should be controlled and directed away from the slope to prevent erosion damage. Another option that may be considered would be to reduce loss of yard space by extending the toe of the slope to the north (toward El Camino Real) from its current location. This scenario would likely result in a composite slope comprised of fill in the lower portion and terrace deposits in the upper portion. - A third option would be to utilize a retaining wall located near the toe of the existing slope in conjunction with a fill slope to achieve an adequate factor of safety. This option would allow the preservation of most or all of the. existing yard space, but would incur significantly higher costs than the options above. Should you have any questions regarding this document or if we may be of further service, please contact our office at your convenience. Very truly yours, SOUTHERN CALIFORNIA SOIk&!FESNlNG, INC I? - ,... No. 107 L Ole Dañift' Ajther, CE 3O3 'So Mike Farr, CEG 1938 - .- Vice Presient . Senior Engineenng Geologist,.......2 DBAMFsd (6) Addressee . Sf1 30 co 10 4"± REE SCS&T LEGEND Qt PALE ORANGE TO LIGHT GRAY, DRY/HUMID, MEDIUM DENSE/DENSE, VERY FINE TO FINE, A CROSS-SECTION A-A' SILTY SANDSTONE, MODERATELY CEMENTED SCALE: V=1O' A' SOUTHERN CALIFORNIA SOIL & TESTING, INC. EUCALYPTUS SUB-DIVISION BY: MF/DCD I DATE: 10/28/04 JOB NO: 0411308-1 1 PLATE: I SLOPE STABILITY CALCULATIONS JANBUS SIMPLIFIED SLOPE STABILITY METHOD AC4i= WHTand, C FS=Ncf(——) WH Assume Homogeneous Strength Parameters Throughout The Slope VE C (øsf) Ws (ocfi Ind. I-I (ft. Existing Configuration 33 150 125 0.5:1 30 Proposed Configuration 33 150 125* 1.5:1 30 1.5: Slope Proposed Configuration 33 150 125* 2:1 30 2:1 Slope Assumed Where: 0 = Angle of Internal Friction C = Cohesion (psf) Ws = Unit Weight of Soil (pcf) H = Height of Slope (ft) FS = Factor of Safety SOI EUCALYPTUS SUBDIVISION L & TESTING, INC. BY: 1 O NUMBER: 11308-1 1PTE NO: 2 I SOUTHERN CALIFORNIA DBAISD bATE: 10/28/2004 FS 0.8 1.5 1.9 DIRECT SHEAR SUMMARY 4500 iI,iIIII 3500 co CL 3000 LU 2500 UJ 2000 1500 1000 500 I 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 NORMAL STRESS [PSF] (2 3/8" SAMPLE) ANGLE OF COHESION INTERNAL INTERCEPT SAMPLE DESCRIPTION FRICTION (°) (PSF) Slope Face Undisturbed 33 150 In-Situ Dry Density = 106.7 pcf In-Situ Moisture Content = 4.7% 02. SOUTHERN CALIFORNIA JBY: EUCALYPTUS SUBDIVISION AIL Q sq SOIL & TESTING, INC. DBAISD DATE: 10/28/2004 JOB NUMBER: 0411308-1 IPLATE NO.: 3 FOIL & TESTING. INC. 2 01 II. -a U 2 II' 0 VI March 4, 2005 Ms. Rachel Mullin Family Real Estate Enterprises, LLC 560 North Coast Highway 101, Suite 1 Encinitas, California 92024 Subject: PROPOSED 1.5:1 SLOPE EUCALYPTUS SUBDIVISION EL CAMINO REAL AND CRESTVIEW DRIVE CARLSBAD, CALIFORNIA P H 0 N E I P.O. Box 600627 (619)280-4321 I San Diego, CA 92160-0627 TOLL FREE I 6280 Riverdale Street (877)215-4321 I. FAX San Diego, CA 92120 (619) 280-4717 www.scst.com SCS&T No. 0411308 Report No. 2 References: 1. Eucalyptus Subdivision, Conceptual Grading Plan, prepared by P&D Consultants, Inc., dated May 26, 2004, latest revision dated February 21, 2005, Project No. 175701. 2. "Slope Evaluation, Eucalyptus Subdivision, El Camino Real and Crestview Drive, Carlsbad, California"; prepared by Southern California Soil and Testing, Inc.; dated October 28, 2004 (SCS&T 04113081). Dear Ms. Mullin: In accordance with your request, we have prepared this letter to address the issue of the proposed 1.5:1 (horizontal:vertical) slope adjacent to the subject site's northern boundary. The proposed slope will replace an existing over-,steepened slope which, as described in Reference No. 2, does not possess an adequate factor-of-safety with respect to slope failure in its current configuration. The configuration of the proposed slope is depicted on the referenced grading plan prepared by P&D Consultants, Inc. Based upon the currently proposed slope configuration, the slope will have a height of about 25 to .36- feet. The lower portion of the. slope will be comprised of fill, while the upper portion will be cut into native terrace deposits. The daylight line between cut and fill will generally occur at about elevation 80 to 85 feet above mean sea level (MSL), which is near the middle of the slope. In our opinion, the proposed 1.5:1 slope is acceptable from a geotechnical point of view and will possess a factor-of-safety greater than 1.5, provided the recommendations presented below are implemented. Slope stability calculations are, presented in Reference No. 2. Our recommendations are as follows: Family Real Estate Enteiprises, LLC March 4, 2005 Eucalyptus Subdivision SCS& T No. 0411308-2 Page 2 The lower, fill portion of the slope should be constructed in accordance with the detail attached hereto as Plate No. 1. A keyway should be constructed atthe bottom of the fill slope. The keyway should have a minimum width of 15 feet, should extend at least.2 feet into dense terrace deposits, and should be tilted back into slope at a gradient of at. least 5 percent. Depending 'upon soil conditions exposed at the time of grading, a subdrain may be required at the heel of. the keyway. All loose talus and colluvium mantling the lower'portion of the slope should be removed and recompacted during slope reconstruction: Horizontal benches should be cut into competent terrace deposits as fill. placement progresses upslope. A 5-foot vertical cut should be made at the contact between the fill and dut portion of the slope. The slope should be over-built by at least 3 feet and trimmed back to the finish slope configuration so that well-compacted fill soils are exposed in the finish slope face. The purpose of overbuilding the slope is to reduce the risk of slope-face erosion. An erosion-protection device and suitable vegetation should be' installed on the slope face as soon as possible after construction. Jute matting or other suitable devices may be utilized. A portion of the proposed driveway for Lot 3 will be located adjacent or very close to the top of the proposed 1.5:1 slope. A concrete footing or thickened edge should be constructed wherever the northern edge 'of the driveway is located within 5 feet of the top of the slope. The depth of the footing should be such that a minimum horizontal distance of 5 feet exists between the lower outside edge of the footing and the slope face. Required footing. depths Will range up to a maximum of about 3.3 feet for areas where the driveway is adjacent to the top of slope, and will decrease with increasing distance between the driveway and the slope. Periodic obseryation and testing should be provided by SCS&T during the work outlined above to verify, compliance with SCS&T recommendation, City of Carlsbad 'grading ordinances and job requirements. tSiC' Family Real Estate Enteiprises, LLC March 4, 2005 Eucalyptus Subdivision S SCS& T No. 0411308-2 Page 3 Should you have any questions regarding this document or if we may 'be of further service, please contact our office at your convenience. . Very truly yours, . . SOUTHERN CALIFORNIA SOIL & TESTING, INC. . ! rn Mike Farr, C G 193.8 Daniel B Adler, RCE36O31 çr" Senior Engineering Geolog1,Q . / Vice Pr sident .. -. S - MF DBA Sd Addressee P&D Consultants, Inc., Attn: Jon Becker Planning Systems, Inc., Attn: Paul Klukas U SOUTHERN CALIFORNIA SOIL & TESTING, INC. TYPICAL 1.5:1 SLOPE DETAIL SCALE: I"= 10' H=V SUBDIVISION S.. NORTH BOUNDARY SOUTH ]RECEIVED APR 25 2006 ENGINEERING DEPARTMENT LM