The URL can be used to link to this page

Home My WebLink AboutCT 99-02; POINSETTIA PROPERTIES PLANNING AREA 7; REPORT OF UPDATED GEOTECHNICAL INVESTIGATION; 1999-01-08I I W CHRISTIAN WHEELER I. ENGINEERING I REPORT . OF UPDATED GEOTECHNICAL INVESTIGATION 1 PACIFIC SHORES NORTH RESIDENTIAL SUBDIVISION POINSETTIA LANE I . I . CARLSBAD, CALIFORNIA I I PREPARED FOR: I . FIELDSTONE COMMUNITIES, INC. - 1 5465. MOREHOUSE DRIVE, SUITE 250 1 . SAN DIEGO, CALIFORNIA 92121 1 .; • I I .. . . . PREPARED BY: . . . 1 . . . CHRISTIAN WHEELER ENGINEERING 4925 MERCURY STREET I . .. SAN DIEGO, CALIFORNIA 92111 • .H. I 4925 Mercury Street + San Diego, CA 92111 4 858-496-9760 4 FAX 858-496-9758 I. CHRISTIAN WHEELER ENGINEERING I i January 8, 1999 Fieldstone Communities, Inc. CWE 198.109.1 I 5465 Morehouse Drive, Suite 250 San Diego, California 92121 I ATrENTION: Mr. Andrew Murphy SUBJECT: Report of Updated Preliminary Geotechnical Investigation, Pacific Shores 1 North Residential Subdivision, Poinsettia Lane, Carlsbad, California. I Gentlemen/Ladies: In accordance with your request and our Proposal dated October 14, 1998, we have completed an updated preliminary geotechnical investigation for the subject property. We are I presenting herewith our findings and recommendations. I In general, we found the site suitable for the proposed residential development, provided the recommendations 'presented in our report are followed. Pertinent geotechnical conditions that will affect the development of the property as proposed are relatively minor and include a I thin veneer of undocumented fill materials and potentially compressible/variable density conditions of the near-surface soils. If you have any questions after reviewing this report, please do not hesitate to contact our office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, CHRISTIAN WHEELER ENGINEERING //,14 Da d g44S' . Russell, Staff Geologist I Charles H. Christian, R.G.E. #00215 çPTc% I-'P3o.GEOOO215i Exp.'9-30-01 •* tip, oFC1 Curtis R. Burdett, C.E.G. #1090 No 1090 •::— CERTIFIED ENGINEERING ° GEOWGIST j Eqs. 10-00 J CHC:CRB:DRR cc: (6) Submitted 4923 Mercury Street + San Diego, CA 92111 + 858-496-9760 + FAX 858-496-9758 TABLE OF CONTENTS PAGE Introduction and Project Description ............................................................................................................... Project Scope ........................................................................................................................................................ . . . .......................................2 Findings.................................................................................................................................................................. SiteDescription............................................................................................................................................3 General Geology and Subsurface Conditions..........................................................................................4 Geologic Setting and Soil Description ........................................... . ..................................................... 4 SurficialSoils...................................................................................................................................... TerraceDeposits ....................................... ........................................................................................ 4 GroundWater.......................................................................................................................................... TectonicSetting........................................................................................................................................6 GeologicHazards .......................................................................................................................................... 6 General......................................................................................................................................................6 Groundshaking.........................................................................................................................................6 SeismicDesign Parameters ............................................. ........................................................................ 7 Landslide Potential and Slope Stability ..................................... ............................................................7 Liquefaction.................................................................................. Flooding...................................................................................................................................................... Tsunamis...................................................................................................................................................8 Seiches.......................................................................................................................................................8 Conclusions................... ........................................................................................................................................8 Recommendations....... ........................................................................................................................................8 Gradingand Earthwork..............................................................................................................................8 Observationof Grading .......................................................................................................................... . ... 8 Clearing and Grubbing............................................................................................................................8 SitePreparation ........................................................................................................................................... 9 Processing of Fill Areas ..........................................................................................................................9 TransitionLot s.........................................................................................................................................9 ExcavationCharacteristics .....................................................................................................................9 Compactionand Method of Filling ...................................................................................................... 10 ImportedFill Material ........................................................................................................................... 11.• Fill Slope Construction ................................................................................. ........................................ 11 SurfaceDrainage ...................................................................................................................................... .ii GradingPlan Review .............................................................................................................................. 12 SlopeStability ................................................................................................................................................ 12 General........................................................................ .. ........................................................................... 12 ErosionControl ...................................................................................................................................... 12 FoundationRecommendations .............................. .................................................................................. 12 General.................................................................. ..................................................................................12 ConventionalFoundations .................................................................................................................... 12 BearingCapacity .......................................................................................... ............................................ .13 Footing Reinforcing ................. ................................................................... . .......................................... 13 LateralLoad Resistance........................................................................................................................13 FootingSetbacks .................................................................................................................................... 13 Foundation Excavation Observation .................................................................................................13 On-Grade Slabs ... ......................................................................................................................................... 14 InteriorSlabs .................................................................................................. . ........................................ 14 Moisture Protection for Interior Slabs ............................................... . ............................................... 14 ExteriorConcrete Flatwork ..................................... ............................................................................ 14 TABLE OF CONTENTS CONTINUED PAGE EarthRetaining Walls ................................................................................................................ ................. 14 PassivePressure ......................... ............................................................................................................14 ActivePressure ......................................................................................................................................... 15 Backfill..................................................................................................................................................... 15 Factorof Safety......................................................................................................................................15 PreliminaryPavement Sections .................................................................................................................. 15 TrafficIndex ....................................................................................................................................... . .... 15 R-Value Test ...................... . ..................................................................................................................... 15 Preliminary Structural Section:.............................................................................................................15 Limitations..........................................................................................................................................................16 Review, Observation and Testing ........................................................ ................................................. 16 Uniformityof Conditions .............................................................. . ........................................................ 16 Changein Scope ......................................................................... .......................................... . ........ . ........ 16 TimeLimitations ............. . ............................................................................................................... . ...... 17 ProfessionalStandard .............................................................................................................................. 17 Client's Responsibility ..................................................................................... ...................................... 17 FieldExplorations .............................................................................................................................................18 LaboratoryTesting............................................................................................................................................18 ATTACHMENTS I I 1 LI [1 1 TABLES Table I FIGURES Figure 1 PLATES Plates IA & lB Plates 2-11 Plate 12 Plate 13 APPENDICES Appendix A Appendix B Maximum Bedrock Accelerations, Page 6 Site Vicinity Map, Follows Page 1 Site Plan Trench Logs Laboratory Test Results Subdrain Detail References, Topographic Maps, Photographs Recommended Grading Specifications - General Provisions UPDATED PRELIMINARY GEOTECHNICAL INVESTIGATION PACIFIC SHORES NORTH RESIDENTIAL SUBDIVISION POINSETTIA LANE CARLSBAD, CALIFORNIA INTRODUCTION AND PROJECT DESCRIPTION This report presents the results of an updated preliminary geotechnical investigation performed for a 110- unit single-family residential development, to be located at the northeast corner of Poinsettia Lane and Carlsbad Boulevard (Highway 101) in Carlsbad, California. The following Figure Number I presents a• vicinity map showing the location of the property. The subject property is a roughly rectangular-shaped, 16.57-acre parcel of land that is to be developed to support 110 single-family residential structures. The homes will be one story and/or two stories in height and are expected to have conventional spread footings with on-grade concrete floor slabs. Grading to develop the property is expected to include the creation of a relatively level parcel, the construction of interior streets, and individual grading on each lot to create relatively level building pads. Although no grading plans were available for our review at the time of the preparation of this report, we anticipate that maximum cuts and fills will be on the order of about ten feet from existing grades. To aid in the preparation of this report, a Topographic Map showing the. existing site grades was provided to us by your office. The Topographic Map received did not include labels indicating the date of production, or by whom the map was prepared. A copy of this map was used as the base for our Site Plan and is included herewith as Plate Numbers IA and 113. In addition, previously prepared geotechnical reports for the subject site and the property directly to the east of the subject site were provided to us for review (Geotechnical Exploration, Inc., 1995 and Geocon, 1988 & 1996). These reports are referenced in the attached appendix. This report has been prepared for the exclusive use of Fieldstone Communities, Inc. and their design consultants for specific application to the project described herein. Should the project be modified, the conclusions and recommendations presented in this report should be reviewed by Christian Wheeler' Engineering for conformance with our recommendations and to determine if any additional subsurface investigation, laboratory testing and/or recommendations are necessary. Our professional services have been performed, our findings obtained and our recommendations prepared in accordance with generally accepted engineering principles and practices. This warranty is in lieu of all other warranties, express or implied. Wheeler Engineering Job Number: 198.109 Date: 12-31-98 Figure Number: 1 M i _S BA.fl • \\\ \\A • • \#\ \.CC \\\ \ \) LEGO FAMILY 3 (FU7URE SITE) • k\\N ) PAL MAR .( AIRP • • - - - - C1O, _______ • - ______ - __ Christian ' CWVERCI flCGIA LII VALII SOUTH suMATal L LOA M _________ • • _____________ C4RLSBAD SITE - - STATE 29 -S FGLTTJA -92 9 S 7300 -... -SAN- IS ::.. 33/ PACIFIC SHORES NORTH Poinsettia Lane & Carlsbad Boulevard Carlsbad, California CWT, 198.109. January 8, 1999 Page No.2 i PROJECT SCOPE I The scope of our update preliminary geotechnical investigation included: surface reconnaissance; subsurface I exploration, obtaining representative undisturbed and bulk samples; laboratory testing; analysis of the field and laboratory data; research of readily available geologic and geotechnical literature pertinent to the site; and preparation of this report. More specifically, the intent of this analysis was to: I a) Review the previously prepared geotechnical documents referenced herein.. I :b) Provide supplementary subsurface explorations to investigate the subsurface conditions of the site to the depths influenced by the proposed construction. c) Evaluate, by supplemental laboratory tests, the engineering properties of the various strata which may influence the proposed development, including bearing capacities and settlement potential. : •. d) Describe the general geology at the site including possible geologic hazards such as seismic •• considerations and perched groundwater, which could have an effect on the site development. I • e) Address potential construction difficulties that may be encountered due to soil conditions, groundwater, or geologic hazards, and provide recommendations concerning these problems. I • • Develop soil engineering criteria for site grading and provide design information regarding the stability of cut and fill slopes. • g) Recommend an appropriate foundation system for the type of structures anticipated and develop soil engineering design criteria for the recommended foundation design. • • h) Provide design parameters for retaining wall design. • : • i) Provide preliminary recommendations for structural pavement sections. • j) Preparation of this report, which contains our conclusions, professional opinions and recommendations,'a site plan, exploration logs, and a summary of the laboratory results. 1 :....: • • CWE 198.109 January 8, 1999 Page No. 3 In addition to this Updated Preliminary Geotechnical Investigation, a Phase I Environmental Site Assessment (ESA) is also being prepared by CWE for the subject site. The findings and results of this ESA I will be submitted under separate cover. I It was not within the scope of our services to perform laboratory tests to evaluate the chemical characteristics of the on-site soils in regard to their potentially corrosive impact to on-grade concrete and I below grade improvements. If desired, we can obtain samples of representative soils and submit them to a chemical laboratory for analysis. We suggest that such samples be obtained after precise grading is I complete and the soils that can affect concrete and other improvements are in place. Further, it should be understood that Christian Wheeler Engineering does not practice corrosion engineering. If such an analysis is necessary, we recommend that the developer retain an engineering firm that specializes in this field to consult with them on this matter. I FINDINGS SITE DESCRIPTION The subject site consists of a roughly rectangular-shaped parcel of land of 16.57 acres in size, which is located at the northeast corner of Poinsettia Lane and Carlsbad Boulevard (Highway 101); in Carlsbad, I California. Current access to the site is afforded by Carlsbad Boulevard (Highway 101), which bounds the property to the west. The subject site is also bounded to the south by Poinsettia Lane, to the north by an I existing mobile home park, and to the east by existing San Diego Northern Railway/Coaster rail lines (including a 100-foot setback). The property is presently undeveloped and appears to have been recently I plowed at the time of our subsurface exploration. Based upon observation of readily available, pertinent aerial photographs, the site appears to have been used for agricultural purposes since 1928 or earlier. Please I referto the Site Plan included herewith as Plate Numbers IA and lB. I Topographically, the site rises gently from the west (along Carlsbad Boulevard) toward the central portion of the site, and then drops gradually to the eastern perimeter of the site towards the existing rail lines. The I existing terrain also generally slopes upward from the south to north. Based upon a topographic map of the• site provided by your office, the on-site elevations are estimated to range from 56 feet above Mean Sea Level I to 66 feet above Mean Sea Level within the western portion of the site, from 63 feet above Mean Sea Level to 71 feet above Mean Sea Level, within the central portion of the site, and from 55 feet above Mean Sea Level to 61 feet above Mean Sea Level along the eastern perimeter of the site. 1 C WE 198.109 January 8, 1999 Page No.4 GENERAL GEOLOGY AND SUBSURFACE CONDITIONS GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located in the Coastal Plains Physiographic Province of San Diego County. Based upon the results of our limited exploration and analysis of readily available, pertinent geologic literature, the site appears to be underlain by a relatively thin veneer of surficial soils above Quaternary-age terrace deposits (Tan and Kennedy, 1996). As observed during our subsurface exploration, the encountered subsurface conditions generally coincide with the findings of the referenced geotechnical reports prepared both for the subject site and the property to the immediate east of the site. The following presents a brief description of the geologic units encountered during Our subsurface exploration. SUIRFICIAL SOILS: A relatively thin zone of surficial topsoil was encountered in each of our ten exploratory test-pits. The topsoil was observed to have maximum thicknesses of approximately twelve inches. The uppermost six inches of the to was noted to generally consist of medium brown silty sand (SM) with occasional organic debris, which were generally damp to moist and loose at the time of our exploration. Encountered at depths of approximately six inches to twelve inches below existing site grades, the topsoil was noted to generally consist of reddish brown silty sand (SM) with lesser amounts of organic debris. The lower portion of the encountered topsoil was observed to be generally damp to moist and loose to medium dense at the time of our exploration. Based upon visual observations of the encountered topsoil, our experience with similar materials in the vicinity of the subject site, and review of readily available geotechnical reports pertinent to the site, we anticipate that the topsoil possess a very low to low expansion potential (Geocon, 1988 and GEl, 1995). Analysis of readily available, pertinent geologic and pedologic literature indicates that the surficial soils at the subject site are mapped within the Marina soil series (USDA, 1970). TERRACE DEPOSITS: The site is underlain at a depth of approximately 12 inches by Quaternary- age, marine and non-marine terrace deposits. This material extends to depths greater than the maximum explored depth of 13Y2 feet below existing grades. The upper ten to 13Y2 + feet of the encountered terrace deposits generally consisted of reddish brown to yellowish brown silty sand (SM) which was generally damp to moist and medium dense to dense at the time of our exploration. Beneath this zone of silty sand (SM), terrace deposits consisting of yellowish brown poorly graded sand (SP) were encountered in eight of our ten exploratory test pits. These deposits of poorly graded sand (SP) were noted to possess little cohesion and to be generally damp to moist and medium dense CAFE 198.109 January 8, 1999 Page No. 5 to dense at the time of our exploration. Approximately 12-inches of the uppermost terrace deposits were noted to be weathered and display variable densities and potentially compressible I characteristics. - I The contact between silty sand (SM) and poorly graded sand (SP) deposits of the terrace deposits was generally observed to coincide with the surf icial topography, by dipping slightly from north to south with a sub-linear ridge extending from north to southwithin the central portion of the site. The uppermost. contact of the poorly graded sand (SP) deposits along the western portion of the site I was observed to be at approximate elevations of between 53 feet to 55 feet above mean sea level in the north to a depth of below 45 feet above mean sea level along the southwestern corner of the site. I Along the sub-linear ridge that extends from north to south within the central portion of the site, the uppermost contact of the poorly graded sands was observed to be at elevations of 58 feet to below 56 I feet above mean sea level. The upper contact of the poorly graded sand (SP) deposits along the eastern portion of the site was observed to dip gently from an elevation of approximately 54 feet I . above mean sea level within the northeast corner of the site, to approximately 49 feet above mean sea level within the southeastern corner of the site. The absence of poorly graded sand deposits (SP) within 13'/2 feet of the surface of our exploratory I : Test Pit P- 10; located at the highest elevation of.all of our test pits, appears consistent with the general local stratigraphy. The absence of poorly graded sand deposits (SP) in our exploratory Test Pit P-6, conducted to a depth of 13 '/2 feet below existing site grades, appears somewhat anomalous I with the general local stratigraphy. However, this anomaly may be explained by variances in local subsidence and depositional conformity such as differential bed thicknesses and erosional surfaces. I As such, based upon the relative consistency of the local stratigraphy, it is anticipated that such deposits are likely present at elevations proximal to those explored.- GROUND WATER: Groundwater was not encountered in any of our exploratory test pits at the time of our I subsurface exploration, but it should be recognized that minor groundwater seepage problems may occur after development of a site even where none were present before development. These are usually minor phenomena and are often the result of an alteration in drainage patterns and/or an increase in irrigation water. Based on the permeability characteristics of the soil and the anticipated usage and development, it is our I opinion that any seepage problems which may occur will be minor in extent. It is further our opinion that these problems can be most effectively corrected on an individual basis if and when they occur. I : '•: : CWE 198.109 January 8, 1999 Page No. 6 Based upon the review of the referenced geotechnical reports, zones of perched groundwater were, in the past, observed to exist on the property located directly to the east of the subject site at the contact between the Quaternary-aged marine terrace deposits and the underlying Tertiary-aged bedrock of the Santiago Formation. The depths of the perched groundwater which was encountered on the property directly east of the site was observed by others to range from approximately 19 to 20 feet below the then existing site grades along the western edge, of that property (Geocon, 1988). As such, it is our opinion that if present, perched groundwater conditions will most likely only be encountered at depths which will not influence the proposed development. TECTONIC SETTING: No major faults are known to traverse the subject site but it should be noted that much of Southern California, including the San Diego County area is characterized by a series of Quaternary- age fault zones which typically consist of several individual, en echelon faults that generally strike in.a northerly to north-westerly direction. Some of these fault zones (and the individual faults within the zones) are classified as active while-others are classified as only potentially active, according to the criteria of the California Division of Mines and Geology. Active fault zones are those which have shown conclusive evidence of faulting during the Holocene Epoch (the most recent 11,000 years) while potentially active fault zones have demonstrated movement during the Pleistocene Epoch (11,000 to 1.8 million years before the present) but no movement during Holocene time. A review of available geologic maps indicates that the active Rose Canyon Fault Zone is located approximately 2.4 miles southwest of the subject site. Other active fault zones in the region that could possibly affect the site include the Coronado Bank and San Clemente Fault Zones to the southwest, and the Elsinore and San Andreas Fault Zones to the northeast. GEOLOGIC HAZARDS GENERAL: No geologic hazards of sufficient magnitude to preclude development of the site as we presently contemplate it are known to exist. In our professional opinion and to the best of our knowledge, the site is suitable for the proposed development. GROUND SHAKING: A likely geologic hazard to affect the site is ground shaking as result of movement along one of the major active fault zones mentioned above. The maximum bedrock accelerations that would be attributed to a maximum probable earthquake occurring along the nearest fault segments of selected fault zones that could affect the site are summarized in the following Table I. CWE 198.109. January 8, 1999 . Page No. 7 TABLE I Fault Zone . Distance Maximum Probable Earthquake Maximum Bedrock. Acceleration Rose Canyon 2.4 miles 6.5 magnitude . , 0.46 g Coronado Bank 19 miles 7.0 magnitude 0.16 g Elsinore 26 miles 7.3 magnitude . 0.15g San Clemente' 55 miles 7.3 magnitude. 0.06 g Probable ground shaking levels at the site could range from slight to moderate, depending on such factors as, the magnitude of the seismic event and the distance to the epicenter: It is likely that the site will experience the effects of at least one moderate to large earthquake during the life of the proposed structures. - SEISMIC DESIGN PARAMETERS: In accordance with the evaluations provided above, the Maximum I .Bedrock Acceleration at the site is 0.46 g (based upon a Maximum Probable Seismic Event of 6.5 Magnitude along the Rose Canyon Fault Zone). For structural design purposes, a damping ratio not greater than 5 I . percent of critical dampening, and Soil Profile Type SD are recommended (UBC Table 16-J). Based upon the location of the site within 3.8 kilometers of the Rose Canyon Fault (Type B Fault), Near Source Factors Na . I. . equal to 1.12 and N, equal to 1.36 are also applicable. Additional seismically related design parameters are recommended to be obtained from the Uniform Building Code (UBC) 1997 edition, Volume II, Chapter 16, utilizing a Seismic Zone 4 LANDSLIDE POTENTIAL AND SLOPE STABILITY: Due to the nature of the encountered, subsurface I materials and the gently sloping topography of the, subject site and immediately adjacent parcels, the potential for both shallow, surficial failures and deep-seated landsliding is considered very low on or immediately I . adjacent to the subject site, provided any and all cut/fill slopes are constructed in accordance with the recommendations contained herein. LIQUEFACTION: The native materials encountered during our subsurface exploration of the site are not I considered subject to liquefaction due to such-factors as soil density and the absence of shallow groundwater conditions. FLOODING: The site is located outside the boundaries of both the 100-year and the 500-year floodplains according to the maps prepared by the Federal Emergency Management Agency. . I CWEI98.109 January 8, 1999 Page No. 8 TSUINA1VIIS: Tsunamis are great sea waves produced by submarine earthquakes or volcanic eruptions. Due to its elevation, the site is considered to at very low to low risk from tsunamis. SEICIIES: Seiches are periodic oscillations in large bodies of water such as lakes, harbors, bays or reservoirs. Due to the site's location, it will not be affected by seiches. CONCLUSIONS In general, we found the subject property suitable for the proposed development, provided the recommendations provided herein are followed. The most significant geotechnical condition that will affect the development of the site as proposed is limited to the variable density/potentially compressible nature of the encountered topsoil and the uppermost terrace deposits. As such, we recommend the complete removal of the topsoils and the uppermost one-foot of the terrace deposits within those areas to receive buildings or other settlement sensitive structures. The removed soils should be replaced ata minimum of 90 percent relative compaction (based on ASTM Test Method Dl 557). RECOMMENDATIONS GRADING AND EARTHWORK OBSERVATION OF' GRADING: Continuous observation by the Geotechnical Consultant is essential during the mass grading operation to confirm conditions anticipated by our investigation, to allow adjustments in design criteriato reflect actual field conditions exposed, and to determine that the grading proceeds in general accordance with the recommendations contained herein. CLEARING AND GRUBBING: Site grading should begin with the removal of all vegetation and other deleterious materials from the portions of site that will be graded and/or will receive improvements. This should include all grasses and significant root material. The resulting materials should be disposed of off- site. It is anticipated that some underground irrigation lines may be encountered that are associated with past I agricultural use of the land. Such lines, if encountered, should be removed from the areas to be graded and the resulting depressions should be cleaned out of loose or disturbed soils and be backfilled with compacted I soil. CWEI98.109 January 8, 1999 Page No. 9 SITE PREPARATION: After clearing and grubbing, site preparation should begin with the removal from areas to receive fill and/or improvements of the topsoil materials and weathered terrace deposits to the depths determined in the field by our project geologist. Based upon the results of our subsurface exploration, these materials are anticipated to extend to depths of approximately 24 inches below existing site grades. It should be noted however, that based upon the observations of our field representative, localized deeper removals may be required: The removed topsoil materials should be either used as non- structural, landscape fill, or thoroughly blended with materials of the underlying terrace deposits prior to replacement as structural fill. PROCESSING OF FILL AREAS: Prior to placing any new fill soils or constructing any new improvements in areas that have been cleaned out to receive fill, the exposed soils should be scarified to a depth of 12 inches, moisture conditioned, and compacted to at least 90 percent relative compaction.. In areas to support fill slopes, keys should be cut into the competent supporting materials. The keys should be at least ten feet wide and be sloped back into the hillside at least two-percent. The keys should extend at least one foot into the competent supporting materials. No other special ground preparation is anticipated at this time. TRANSITION LOTS: Where transitions between cut and fill material falls within a lot, we recommend that the cut portion of the lot be over-excavated by a depth of three feet and said material replaced as uniformly compacted fill. Undercut areas should be sloped toward the fill area of the lot to prevent water that seeps into the ground from becoming perched above the natural soils. Lots with cut/fill transitions that will need to be undercut should be identified by the project geologist during grading. EXCAVATION CHARACTERISTICS: Based upon the lack of cementation of the encountered sub- surface materials, the ease of excavation of the ten exploratory test pits, and review of the referenced geotechnical reports, the subsurface materials at the site appear generally rippable with conventional earthmoving equipment to a depth of at least 131/2 feet below existing site grades. Significant caving of the test pit walls was not encountered at the time of our subsurface exploration. However, the friable nature and relatively low cohesion values of the poorly graded sand (SP) portions of 0 the terrace deposits indicates that such materials may experience caving when conducting deep and/or steep sided excavations, such as sewer trenches. Observations made during our subsurface exploration indicate that such poorly graded sand (SP) deposits exist along the western portion of the site at depths below approximate elevations of between 53 feet to 55 feet above mean sea level in the north to a depth of below 45 CWE 198.109 January 8, 1999 Page No. 10 feet above mean sea level along the southwestern corner of the site. Within the raised, central portion of the site, the poorly graded sand (SP) deposits were observed to be at elevations of 58 feet to below 56 feet above mean sea level. Along the eastern portion of the site, poorly graded sand (SP) deposits were noted at approximate elevations of 54 feet above mean sea level in the northeast, to 49 feet above mean sea level in the southeast. The contractor is solely responsible for designing and constructing stable, temporary excavations and may need to shore, slope, or bench the sides of trench excavations as required to maintain the stability of the excavation sides where the friable sands are exposed. The contractor's "responsible person", as defined in the OSHA Construction Standards for Excavations, 29 CFR, Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety process. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety regulations. COMPACTION AND METHOD OF FILLING: All structural fill placed at the site should be compacted to a relative compaction of at least 90 percent of maximum dry density as determined by ASTM Laboratory Test D1557, Method A or C. Fills should be placed at or slightly above optimum moisture content, in lifts six to eight inches thick, with each lift compacted by mechanical means. Fills should consist of approved earth material, free of trash or debris, roots, vegetation, or other materials determined to be unsuitable by our soil technicians or project geologist. Fill material should be free of rocks or lumps of soil in excess of twelve inches in maximum dimension. However, in the upper two feet of pad grade, no rocks or lumps of soil in excess of six inches should be allowed. Based upon the results of our sub-surface exploration and laboratory testing most of the on-site soils appear suitable for use as fill material. Fills should be benched into all temporary slopes and into competent natural soils when the natural slope is steeper than an inclination of 5:1 (horizontal to vertical). Keys should be constructed at the toe of all fill slopes. The keys should extend at least 12 inches into firm natural ground and should be sloped back at least two percent into the slope area. Slope keys should have a minimum width of 10 feet. Utility trench backfill within five feet of the proposed structures and beneath driveways, concrete flatwork, and pavements should be compacted to a minimum of 90 percent of its maximum dry density. The upper twelve inches of subgrade beneath paved areas should be compacted to 95 percent of its maximum dry density. This compaction should be obtained by the paving contractorjust prior to placing the aggregate base material and should not be part of the mass grading requirements. CWE 198.109 January 8, 1999 Page No. 11 All grading and fill placement should be performed in accordance with the City of Carlsbad Grading Ordinance, the Uniform Building Code, and the attached Recommended Grading Specifications and Special Provisions attached hereto as Appendix B. S I IMPORTED FILL MATERIAL: At this time, the need to import fill material is not anticipated. If, however, imported fill is necessary, it should be evaluated and approved by the geotechnical consultant prior to being imported. At least two working days notice of a potential import source should be given to the Geotechnical Consultant so that appropriate testing can be accomplished. The type of material considered 1 most desirable for import is granular material containing some silt or clay binder, which has an expansion index of less than 50. I FILL SLOPE CONSTRUCTION: Fill slopes may be constructed at an inclination of 2:1 or flatter I (horizontal to vertical). Compaction of slopes should be performed by back-rolling with a sheepsfoot compactor at vertical intervals of four feet or less as the fill is being placed, and track-walking the face of the slope when the, slope is completed. As an alternative, the fill slopes maybe overfilled by at least three feet and then cut back to the compacted core at the design line and grade. Keys should be made at the toe of fill slopes in accordance with the recommendations presented above under "Compaction and Method of Filling." Due to the grain size distribution and relatively low cohesion/friable nature of the poorly graded sand (SP) encountered below approximate elevations of between 58 feet and below 45 feet above mean sea level, care should be taken to ensure that-poorly graded sands (SP) not be placed within ten feet of the face of fill slopes. This measure is designed to help minimize erosion along such fill slope faces. SURFACE DRAINAGE: Surface runoff into downslope natural areas and graded areas should be minimized. Where possible, drainage should be directed to suitable disposal areas via non-erodible devices such as paved swales, gunited brow ditches, and storm drains. Pad drainage should be designed to,collect and direct surface water away from proposed structures and the top of slopes and toward approved drainage areas. For earth areas, a minimum gradient of one percent should be maintained. The ground around.homes should be graded so that surface water flows rapidly away from the structure . without ponding. In general, we recommend that the ground adjacent to structures slope away at a gradient' of at least two percent. Densely vegetated areas where runoff can be impaired should have a minimum gradient of at least five percent within the first three feet from the structure. C WE 198.109 January 8, 1999 Page No. 12 Homeowners should be advised that drainage patterns approved at the time of fine grading should be maintained throughout the life of the proposed structures. They should also be advised to limit site irrigation to the minimum necessary to sustain landscape growth. Should excessive irrigation, impaired drainage, or unusually high rainfall occur, saturated zones of perched groundwater conditions may occur. We suggest that rain gutters and downspouts be installed on all homes to help control roof runoff. GRADING PLAN REVIEW: The final grading plans should be submitted to this office for review in order to ascertain that the recommendations of this report have been implemented, and that no additional recommendations are needed due to changes in the anticipated development plans. SLOPE STABILITY GENERAL: All slopes proposed at the subject development should be constructed at a slope ratio of 2.0 horizontal units to 1.0 vertical unit (2:1) or flatter. We anticipate that maximum cut and fill slope heights will be less than about ten.feet. All fill slopes should be constructed in accordance with the grading recommendations. EROSION CONTROL: The placement of cohesionless soils within ten feet of the face of slopes'should be avoided. Slopes should be planted as soon as feasible after grading. Sloughing, deep rifling and slumping of surficial soils may be anticipated if slopes are left unplanted for a long period of time, especially during the rainy season. Irrigation of slopes should be carefully monitored to insure that only the minimum amount necessary to sustain plant life is used. Over-irrigating could be extremely erosive and should be avoided. FOUNDATION RECOMMENDATIONS GENERAL: Our investigation indicated that the proposed homes may be supported by conventional continuous and isolated spread footings. Due to the generally low to very low expansive potential of the native soils, special consideration and design for heaving soils will not be required. CONVENTIONAL FOUNDATIONS: Spread footings supporting one-story and two-story homes should be embedded at least 12 and 18 inches below finish pad grade, respectively. Continuous and isolated spread footings should have a minimum width of 12 inches and 18 inches, respectively. CWE 198.109 January 8, 1999 Page No. 13 BEARING CAPACITY: Conventional spread footings with the above minimum dimensions may be ' designed for an allowable soil bearing pressure of 2250 pounds per square foot. This value may be increased by one-third for combinations of temporary loads such as those due to wind or seismic loads. I FOOTING REINFORCING: Reinforcement requirements for foundations shouldbe provided by a structural engineer. However, based on the existing soil conditions, we recommend that the minimum I reinforcing for continuous footings consist of at least one No. 5 bar positioned three inches .above the bottom of the footing and one No. 5 bar positioned two inches below the top of the footing. I LATERAL LOAD RESISTANCE: Lateral loads against foundations may be resisted by friction between the bottom of the footing and the supporting soil, and by the passive pressure against the footing. The coefficient of friction between concrete and soil may be considered to be 0.40. The passive resistance may be considered to be equal to an equivalent fluid weight of 350 pounds per cubic foot. This assumes the footings are poured tight gainst undisturbed soil. If a combination of the passive pressure and friction is used, the friction value should be reduced by one-third. FOOTING SETBACKS: If footings for structures are proposed adjacent to the top of slopes, we recommend that a minimum horizontal setback from the outer edge of the footing to the adjacent slope face be provided. The minimum setback from the slope face recommended is 5 feet from slopes 0 to 15 feet high. If higher slopes will exist, CWE should be contacted for additional recommendations. The building setback distance from the top of slopes may be modified by using deepened footings. Footing setback is measured from competent soil and should neglect any loose or soft native soils that may occur at the top of a natural slope. Footings planned under the specified setbacks should be provided specific review by the Geotechnical Consultant prior to construction. FOUNDATION EXCAVATION OBSERVATION: All foundation excavations should be observed by the Geotechnical Consultant prior to placing concrete to determine if the foundation recommendations presented herein are complied with. All footing excavations should be excavated neat, level and square. All loose or unsuitable material should be removed prior to the placement of concrete. CWE 198.109 January 8, 1999 Page No. 14 ON-GRADE SLABS. I INTERIOR FLOOR SLABS: For conventional floor slabs, the minimum slab thickness should be four inches. Interior floor slabs should be reinforced with at least No. 3 bars placed at 18 inches on center each I way. The slab reinforcing bars should be turned down to extend at least six inches into the perimeter footings. Slab reinforcing should be positioned on chairs at mid-height in the floor slab. The garage slabs may be constructed independent of the garage perimeter footings. Garage slabs should have the same reinforcing and thickness recommended above for the living area of the house. MOISTURE PROTECTION FOR INTERIOR SLABS: Interior concrete on-grade floor slabs that will I support moisture-sensitive floor covering should be underlain by a moisture barrier. We recommend that the minimum configuration of the subslab moisture barrier consist of a four-inch-thick blanket of coarse I clean sand. The moisture barrier material should have less than ten percent and five percent passing the No. 100 and No. 200 sieves, respectively. A visqueen vapor barrier should be placed in the center of the sand I blanket. . S I . EXTERIOR CONCRETE FLATWORK: Exterior slabs should have a minimum thickness of four inches. Reinforcement and control joints should be constructed in exterior concrete flatwork to reduce the I .potential for cracking and movement. Joints should be placed in exterior concrete flatwork to help control the location of shrinkage cracks. Spacing of control joints should be in accordance with the American I .. Concrete Institute specifications. When patio, walks and porch slabs abut perimeter foundations they should be doweled into the footings. . EARTH RETAINING WALLS I PASSIVE PRESSURE: The passive pressure for the prevailing soil conditions may be consideredto be 350 pounds per square foot per foot of depth. This pressure may be increased one-third for seismic loading. The coefflcient of friction for concrete to soil may be assumed to be 0.40 for the resistance to lateral movement. When combining frictional and passive resistance, the friction should be reduced by one-third. The upper 12 inches of exterior retaining wall footings should not be included in passive pressure calculations where abutted by landscaped areas. I. •S S I CWEI98.109 January 8, 1999 Page No. 15 ACTIVE PRESSURE: The active soil pressure for the design of unrestrained earth retaining structures with level backfill may be assumed to be equivalent to the pressure of a fluid weighing 30 pounds per cubic foot. An additional 13 pounds per cubic foot should be added to said value for 2: (horizontal to vertical) sloping backfill. These pressures do not consider any other surcharge. If any are anticipated, this office' I should be contacted. for the necessary increase in soil pressure. These values assume a drained baôkfill condition. Waterproofing details should be provided by the project architect. A suggested wall subdrain I detail is provided on the attached Plate Number 13. We recommend that the Geotechnical Consultant observe all retaining wall subdrains to verify proper construction. BACKFILL: All backfill soils should be compacted to at least 90 percent relative compaction. Expansive or clayey soils should not be used for.backfill material. The wall should not be backfilled until the masonry has reached an adequate strength. FACTOR OF SAFETY: The above values, with the exception of the allowable soil friction coefficient, do not include a factor-of-safety. Appropriate factors-of-safety should be incorporated into the design to prevent the walls from overturning and sliding. PRELIMINARY PAVEMENT SECTIONS TRAFFIC INDEX: Based upon the minimum requirements of the City of Carlsbad, a traffic index of 5.0 has been applied to the local streets which will support the individual lots of the subject site. R-VALUE TEST: An R-Value test was performed on the near-surface material that is expected to be present in most of the street subgrade. The result of this test indicated that the near-surface material will have an R-value of approximately 66. This value was used in determining the required structural pavement section. • PRELIMINARY STRUCTURAL SECTION: Based on the above parameters and the minimum structural section allowed by the City of Carlsbad, it was determined that the structural pavement section should consist of 4.0 inches of asphalt concrete on 4.0 inches of Crushed Aggregate Base material, as per Section 200-2.2 of the Standard Specifications for Public Works Construction. CWEI98.109 January 8, 1999 Page No. 16 LIMITATIONS REVIEW, OBSERVATION AND TESTING The recommendations presented in this report are contingent upon our review of final, plans and specifications. Such plans and specifications should be made available to the geotechnical engineer and engineering geologist so that they may review and verify their compliance with this report and with the Uniform Building Code. It is recommended that Christian Wheeler Engineering be retained to provide continuous soil engineering services during the earthwork operations. This is to verify compliance with the design concepts, specifications or recommendations and to allow design changes in the event that subsurface conditions differ from those anticipated prior to start of construction. UNIFORMITY OF CONDITIONS The recommendations and opinions expressed in this report 'reflect our best estimate of the project requirements based on an evaluation of the subsurface soil conditions encountered at the subsurface exploration locations' and on the assumption that the soil conditions do not deviate appreciably from those encountered. It should be recognized that the performance of the foundations and/or cut and fill slopes may be influenced by undisclosed or unforeseen variations in the soil conditions that may occur in the intermediate and unexplored areas. Any unusual conditions not covered in this report that may be encountered during site development should be brought to the attention of the geotechnical engineer so that he may make modifications if necessary. CHANGE IN SCOPE This office should be advised of any changes in the project scope or proposed site grading so that we may determine if the recommendations contained herein are appropriate. This should be verified in writing or modified by a written addendum. ' CWE 198.109 January 8, 1999 Page No. 17 TIME LIMITATIONS The findings of this report are valid as of this date. Changes in the condition of a property can, however, occur with the passage of time, whether they be due to natural processes or the work of man on this or adjacent properties. In addition, changes in the Standards-of-Practice and/or Government Codes may occur. Due to such changes, the findings of this report may be invalidated wholly or in part by changes beyond our control. Therefore, this report should not be relied upon after .a period of two years without a review by us verifying the suitability of the conclusions and recommendations. PROFESSIONAL STANDARD In the performance of our professional services, we comply with that level of care and skill ordinarily exercised by members of our profession currently practicing under similar conditions and in the same locality. The client, recognizes that subsurface conditions may vary from those encountered at the locations where our borings, surveys, and explorations are made, and that our data, interpretations, and recommendations be based solely on the information obtained by us. We will be responsible for those data, interpretations, and recommendations, but shall not be responsible for the interpretations by others of the information developed. Our services consist of professional consultation and observation only, and no warranty of any kind whatsoever, express or implied, is made or intended in connection with the work performed or to be performed by us, or by our proposal for consulting or other services, or by our furnishing . * of oral or written reports or findings. - - CLIENT'S RESPONSIBILITY It is the responsibility of Fieldstone Communities, Inc., or their representatives to ensure that the information and recommendations contained herein are brought to the attention of the structural engineer and architect for the project and incorporated into the project's plans and specifications. It is further their responsibility to take the necessary measures to insure that the contractor and his subcontractors carry out - such recommendations during construction. CWE 198.109 January 8, 1999 Page No. 18 FIELD EXPLORATIONS Ten subsurface explorations were made at the locations indicated on the site plan included herewith as Plate Numbers IA and I B on December 2, 1998. These explorations consisted of trenches excavated with a backhoe. The fieldwork was conducted under the direction of our engineering geology personnel. The explorations were carefully logged when made. The trench logs are presented on the following Plate Numbers 2 through Ii. The soils are described in accordance with the Unified Soils Classification. In addition, a verbal textural description, the wet color, the apparent moisture and the density or consistency are provided. The density of the granular soils is given as either very loose, loose, medium dense, dense or very dense. Undisturbed chunk samples of typical and representative soils were obtained and returned to the laboratory for testing. Bulk samples of disturbed soil were also collected in bags from the bucket of the backhoe. LABORATORY TESTING Laboratory tests were performed in accordance with the generally accepted. American Society for Testing and Materials (ASTM) test methods or suggested procedures. A brief description of the tests performed is presented below: CLASSIFICATION: Field classifications were verified in the laboratory by visual examination. The final soil classifications are in accordance with the Unified Soil Classification System. MOISTURE-DENSITY: In-place moisture contents and dry densities were determined for representative soil samples. This information was an aid to classification and permitted recognition of variations in material consistency with depth. The dry unit weight is determined in pounds per cubic foot, and the in-place moisture content is determined as a percentage of the soil's dry weight. The results of these tests are summarized in the trench logs. c) GRAIN SIZE DISTRIBUTION: The grain size distribution was determined from representative samples of the terrace deposits in accordance with ASTM D422. The results of these tests are presented on Plates Number 12. S CWE 198.109 January 8, 1999 S Page No. 19 COMPACTION TEST: The maximum dry densities and optimum moisture contents of two typical on-site soil samples were determined in the laboratory in accordance with ASTM Standard Test D- 1557-91, Method A. The result of these tests are presented on Plate Number 12. DIRECT SHEAR TEST: Direct shear test were performed on two representative soil samples to determine the failure envelopes based on yield shear strength. The shear boxes were designed to accommodate samples having a diameter of 2.375 inches or 2.50 inches and a height of 1.0 inch. Samples were tested at different vertical loads and a saturated moisture content. The shear stress was applied at a constant rate of strain of approximately 0.05 inch per minute. The results of these tests are presented on the attached Plate Number 12. 0 RESISTANCE VALUE: The Resistance Value (R-Value) of a representative soil sample was determined to provide a basis for determining the required structural pavement sections. The test was performed in accordance with California Test Method 301-1978, and the results of this test are presented on Plate No. 12. 5 5 CHRIS11AN WHEELER I . ENGINEERING LOG OF PIT NUMBER P1 Date Drilled: 12-02-98 Logged by: DPR Equipment: Badkhoe Driving Weight and Drop: Surface Elevation (ft): 65.0' Depth to Water (ft): Project Máhager: cc 0 1) SUMMARY OF SUBSURFACE CONDITIONS . . . SAMPLES 0 0 o . .< 1J p0.4 SM TOPSOIL - Medium Brown, Moist, Loose, SILTY SAND, Occasional Organic Debris Reddish Bro,in, Moist, Loose: tà Medium Dense, SILTY SAND, Occasional Organic Debris . — - - S SM SM , 000l , CK BAG TERRACE DEPOSITS (Qt) - Reddish Brawn, Moist, Medium Dense, SILTY SAND Orangish Brown to Yellowish Brown Yellowish Brown, Moist, Medium Dense, POORLY-GRADED SAND CK 5.4 7.4 6.2 113.1 116.8 109.9 CK CK CK CK ___ - S - SP S - S CK — Bottom of Test Pit at 13.5 Feet Project Name:. PACIFIC SHORES NORTH Project No. 198.log Plate No. 2 Date Drilled: 12-02-98 Equipment: Backhoe Surface Elevation (ft): 64.0 CHRJS11AN WHEELER ENGINEERING LOG OF PIT NUMBER P2 Logged by: DRR Project Manager: CHC Driving Weight and Drop: N/A Depth to Water (ft): - SAMPLES SUMMARY OF SUBSURFACE CONDITIONS I . P 10~. : - SM TOPSOIL - Medium Brown, Moist, Loose, SILTY SAND, Very Abundant Organic Debris Reddish Brown, Moist, Loosed to Medium - SM Dense, SILTY SAND, Occasional Organic -... Debris 4.5 109 TERRACE DEPOSITS (Qt) - Reddish Brawn, SM - Moist, Medium Dense, SILTY SAND 4.0 111.0 - Grades to Orangish-Brown/Yellowish 00 B~IG - Brawn '5, CK • 0• 0 Yellowish Brown, Moist, Medium Dense, - 7.3 111.1 CK SP -. POORLY-GRADED SAND - S B1G, cz ;B Bottom of Test Pit at13.5 Feet Project Name: PACIFIC SHORES NORTH Project No. 198-109 Plate No. 3 w. CHRJS11AN WHEELER ENGINEERING LOG OF PIT NUMBER P3 Date Drilled: 12-02-98 Logged by: DRR Project Manager: CHC Equipment: Backhoe Driving Weight and Drop: N/A Surface Elevation (ft): 63.0' Depth to Water (ft): - - SUMMARY OF SUBSURFACE CONDITIONS S • SAMPLES '-4 0 0 0 ' 0 1 SM. TOPSOIL - Medium Brown, Moist, Loose, SILTY SAND, Very Abundant Organic Debris. Reddish Brown, Moist, Loose toMëdium Dense, SILTY SAND, Occasional Organic Debris - 2.7 — - - - - SM -- EM 117.9 CK TERRACE DEPOSITS (Qt) - Reddish Brown, Moist, Medium Dense, SILTY SAND Grades to Orangish Brown to Yellowish Brown Light Yellowish Brown, Moist, Medium Dense, POORLY-GRADED SAND < 4.3 7.1 105.8 111.3 CK * S - - - Mo sp Bottom of'TestPit at 13.5 Feet •0 w CHRJS11AN WHEELER ENGINEEPING LOG OF PIT NUMBER P4 - Date Drilled: 12-02-98 Logged by: DRR Project Manager: CRC Equipment: Backhoe Driving Weight and Drop: N/A Surface Elevation (ft): 61.0' Depth to Water (ft): • SAMPLES p 1:4 .• SUMMARY OF SUBSURFACE CONDITIONS 0 0 coo - SM TOPSOIL.- Medium Brown, Moist, Loose, SILTY 'SAND, Very Abundant Organic Debris Reddish 'Brown, Moist, Loose to Medium — SM Dense, SILTY SAID, Occasional Organic Debris S - SM TERRACE DEPOSITS (Qt) - Reddish Brown, - • Moist, Medium Dense,' SILTY SAND • - ' ' • / ,,,. ___ • - ' 4.5 lll. CK - • BlG" CK - Grades to Orangish Brown to Yellowish Brown ' • 7.7 113.0 • Yellowish Brown, Moist, Medium Dense, POORLY-GRADED SAND ' SA ,BAG" - - Si, S - S • BAG DS • S - • .- 'S Bottom of Test Pit at 13.5 Feet Project Name: PACIFIC sois NORTH - ProjectNo. 198.109 Plate No' S • 4 Date Drilled. 12-02-98 Equipment: Baclthoe Surface Elevation (ft): 59.0' CHRISTIAN WHEELER ENGINEERING LOG OF PIT NUMBER P5 Logged by: DRR Project Manager: Driving Weight and Drop: N/A Depth to Water (ft): CHC SAMPLES SUMMARY OF SUBSURFACE CONDITIONS a g. S 0 - c' mcci S SM TOPSOIL - Medium Brown, Moist, Loose, SILTY SAND, Very Abundant Organic Debris - SMReddish Brown Moist, Loose to Medium Dense..-SILTY AND SM TERRACE DEPOSITS (Qt) - Reddish Brown, - Moist, Medium Dense, SILTY SAND, - Ocasiona1 Organic Debris S - S BAG BAG - S - - - S - • S ___ CK - sp. Light Yellowish Brown, Moist, Medium - - Dense, POORLY-GRADED SAND - Bottom of Test Pit at 13.5 Feet Project Name: - PACIFIC SHORES NORTH Project No. 193.109 PlateNo. 6 Date Drilled: 12-02-98 Equipment: Backhoe Surface Elevation (ft): 58.0' w CHRJS11AN WHEELER. ENGINEERING LOG OF PIT NUMBER P6 Logged by: DRR Project Manager: ciic Driving Weight and Drop: N/A Depth to Water (ft): - SAMPLES SUMMARY OF SUBSURFACE CONDITIONS 0 0 Cn 0 ch - SM TOPSOIL - Medium Brown, Moist, Loose, SILTY SAND, Very Abundant Organic Debris - SM Reddish Brown, Moist, Loose to Medium Dense, SILTY SAND, Occasional Organic - Debris TERRACE DEPOSITS (Qt) - Reddish Brown, SM - Moist, Dense, SILTY SAND - Medium Dense - Light Orangish Brown to Yellowish - Brown 7.0 111.4 7, BAG' "7 1. CK - • : BAG, Bottom of Test Pit at 13.5 Feet Project Name: PACIFIC SHORES NORTH Project No. 198. 109 Plate No w CHRJS11AN WHEELER ENGINEERING LOG OF PIT NUMBER P7 Date Drilled: 12-02-98 Logged by: DP Project Manager: Equipment: Backhoe Driving Weight and Drop: N/A Surface Elevation (ft): 68.0 Depth to Water (ft): SAMPLES Q SUMMARY OF SUBSURFACE CONDITIONS • o 0 0 0 SM TOPSOIL - Medium Brown, Moist, LOose, SILTY SAND, Very Abundant Organic Debris • Reddish Brown, Moist, Loose to Medium SM -.-... Dense, SILTY SAND, Occasional Organic Debris S BAG TERRACE DEPOSITS (Qt) - Reddish Brown, ,-' ,-" R SM Moist, Medium Dense, SILTY SAND C-' 4.7 110.9 Orangish Brown to Yellowish Brown • 0 cK • __ • 7.4 116.8 • SP Light Brown to Yellowish Brown, Moist, -• Medium Dense, POORLY-GRADED SAND- - BAG7 57G , • __________________________ Bottom of Test Trench at 13.5 Feet Project Name: PACIFIC SHORES NORTh Project No. 198.109 • Plate No. 8 w CHRJS11AN WHEELER ENGINEER. INC LOG OF PIT NUMBER P8 Date Drilled: 12-02-98 Logged by:* DRR Project Manager: CHC Equipment: Bac]c.hoe Driving Weight and Drop: N/A Surface Elevation (ft): 65.0' Depth to Water (ft): P4 SUMMARY OF SUBSURFACE CONDITIONS SAMPLES 0 S 15 - - - - - - S SM TOPSOIL - Medium Brown, Moist, Loose, SILTY SAND, Abundant Organic Debris Reddish Brown, Moist, Medium Dense to Dense, SILTY SAND, Occasional Organic Debris - - ____ ____ SM SM _____ ____ -, CK / , r32G / TERRACE DEPOSITS (Qt) - Reddish Brown, Moist, Medium Dense to Dense, SILTY SAND S S / / / BAG 3.3 8.0 119.7 120.7 CK BAG CK BAG CK - - S - S - SP Light' Orangish Brown to Yellowish Brown, Moist,. Medium Dense, POORLY- GR7DED SAND S S Bottom of Test Pit at 13.5 Feet S Project Name: PACIFIC SHORES NORTH Project No. 198.109 Plate No. 9 Plate No. 10 w CHRJS11AN WHEELER EN G IN E ER. INC LOG OF PIT NUMBER P9 Date Drilled: 12-02-98 Logged by: DPR Project Manager: Cl-IC Equipment: Backhoe Driving Weight and Drop: N/A. Surface Elevation (ft): 65.0' . Depth to Water (ft): .2. SUMMARY OF SUBSURFACE CONDITIONS SAMPLES . - - - - - SM TOPSOIL - Medium Brown, Moist, Loose, SILTY SAND, Very Abundant Organic Debris Brown, Moist, Loose to Medium Dense, SILTY SAND, Occasional Oiqanic SM -Reddish —..Debris CK EM TERRACE DEPOSITS (Qt) - Reddish Brown, Moist, Dense, SILTY SPND . Orangish Brown t Yellowish Brown . 6 6.9 7.5 116.7 110.3 ,B1G, CK . CK . - - SP . Light Yellowish Brown, Moist, Medium Dense, .POORLY-GRADED SAND Bottom of Test Pit at 13.5 Feet . w CHRJS11AN WHEELER ENGINEERING LOG OF PIT NUMBER PlO Logged by: DRR Project Manager: CHC Driving Weight and Drop: N/A Depth to Water (ft): Date Drilled: 12-02-98 Equipment: Backhoe Surface Elevation (ft): [*ASI SAMPLES S F- SUMMARY OF-SUBSURFACE CONDITIONS . Q (I) — cz 55 SM IOPSOIL - Medium Brown, Moist, Loose, SILTY SAND, Very Abundant Organic Debris - Reddish Brown, Moist, Loose toMedium SM • Dense, SILTY SAND, Occasional Organic - - Debris . BAG' TERRACE DEPOSITS (Qt) -.Reddish Brown, (I 7.4 123.2 EM - Moist, Dense, SILTY SAND S 5 .- - . CK 5 . S 8.5 115.6 - Orangish Brown to Light Yellowish Brown . S • • - S BAG,. MD SA . . • DS 5. CK - S • 5.7, 112.2 • d BAG,,' - Bottom of Test Pit at 13.5 Feet Project Name: PACIFIC SHORES NORTH • Project No. 198 .109 Plate No. 11 I . LABORATORY TEST RESULTS PACIFIC SHORES NORTH RESIDENTIAL SUBDIVISION I MAXIMUM DENSITY! OPTIMUM MOISTURE CONTENT Sample Number Trench # 4 @ 10'-13' I Description . Poorly Graded SAND (SP) Maximum Density 109.9 PCF Optimum Moisture Content. 14.7 Percent I I DIRECT SHEAR TEST Sample Number Trench # 4 @ 10' - 13' I . Description Remolded To 90 Percent * . Angle of Friction 31 Degrees Apparent Cohesion 100 PSF 1 I GRAIN SIZE DISTRIBUTION Sample Number I Sieve Size LI #15 #30 I #50 #100 #200 1 RESISTANCE VALUE TEST (R-VALUE) Sample Number Trench # 7 @ 1'- 4' R-Value by Expansion . 66 R-Value by Exudation . 66 Trench # 4 @ 10'-13' Percent Passing 100 100 100 90 35 6 2 Trench # 10 @ 6'-8' Silty SAND (SK 122.1 PCF 9.9 Percent Trench # 10 @ 6'-8' Percent Passing 100 100 100 93 51 22 15 Trench # 10 @ 6'— 8' Remolded To 90 Percent 32 Degrees 130 PSF January 8, 1999 Plate No. 12 • 1% SLOPE MiNiMi-s'' i T 6 MIN S - 6" MAX • S____ ___ WATERPROOF BACK OF WALL • PER ARCHITECT'S SPECIFICATIONS • 0 .• . ____ 3/4 INCH CRUSHED ROCK or • MIRADRAIN 6000 or EQUIVALENT GEOFABRIC BETWEEN ROCK AND SOIL :12' • TOP OF GROUND or CONCRETE SLAB • • • •611Mj 01 ' - _ I MINIMUM I I 4 INCH DIAMETER I PERFORATED PIPE • • S RETAINING WALL SUBDRAIN DETAIL S No Scale CWE 198.109 January 8, 1999 Appendix A, Page Al REFERENCES I Anderson, J.G.; Rockwell, R.K. and Agnew, D.C., 1989, Past and Possible Future Earthquakes of Significance to the San Diego Region, Earthquake Spectra, Volume 5, No. 2, 1989. Geotechnical Investigation For Poinsettia Promenade, Carlsbad, California, prepared by Geocon I Incorporated, File No. D-4052-JO 1, dated January 26, 1988, including update Project No. 05684-12-01, dated February. 14, 1996. S I ... Jennings, C.W., 1975, Fault Map of California, California Division of Mines and Geology, Map No. 1, Scale 1:750,000. I Kern, P., 1989, Earthquakes and Faults in San Diego County, Pickle Press, 73 pp. Maps of Known Active Fault Near Source-Zones in California and Adjacent Portions of Nevada, 1988, California Division of Mines and Geology. Mualchin, L. and Jones, A.L., 1992, Peak Acceleration from Maximum Credible Earthquakes in California (Rock and Stiff-Soil Sites) California Division of Mines and Geology Open-File Report 92-1. Report of Preliminary Geotechnical Investigation, Caracol Condominium Project, Northeast Corner of Poinsettia Lane and Carlsbad Boulevard, Carlsbad, California, prepared by Geotechnical Exploration, Inc., Job No. 91-6085.1, dated 14 April 1995. Tan, S.S., 1995, Landslide Hazards in the Northern Part of the San Diego Metropolitan Area, San I Diego County, California, California Division of Mines and Geology Open-File Report 95-03. Tan, Siang S., and Kennedy, Michael P., 1996, Geologic Maps of the Northwestern Part of San Diego, County, California, California, California Division of Mines and Geology Open-File Report 96-02. I United States Department of Agriculture, 1970, Soil Survey, San Diego Area, California. Wesnousky, S.G., 1986, "Earthquakes, Quaternary Faults, and Seismic Hazards in California", in I Journal of Geophysical Research, Volume 91, No. B12, pp 12,587 to 12,631, November 1986. CWE 198.109 January 8, 1999 TOPOGRAPHIC MAPS San Diego County, 1960, 200 Scale Maps, Sheets 338-1671 and 342-1671. Appendix A, Page A2 4 San Diego County, 1978, 200 Scale Maps, Sheets 338-1671 and 342-1671. U.S. Geological Survey, 1968 (Photo-revised 1975), 1V2 Minute Topographic Map, Encinitas Quadrangle, scale 1:24,000. PHOTOGRAPHS Aerial FotoBank/Thomas Bros., Inc., Aerial Foto-Map Book, San Diego County, 1995-96, Sheet 1126, Scale: 1 inch = 2000 feet (approximate). S Aerial Graphics, Aerial Foto-Map Book, San Diego County, 1982, Sheet D-8, Scale: 1 inch = 2000 feet (approximate). Aerial Graphics, Aerial Foto-Map Book, San Diego County, 1984-85, Sheet 8-D, Scale: 1 inch = 2000 feet (approximate). Lenska Aerial Images, 1994, The Thomas Guide, Commercial Edition, Page 1126, Scale: 1 inch = 2000 feet (approximate). S San Diego County, 1928, Flight B, Photograph 1: Scale: 1 inch = 1000 feet (approximate). San Diego County, 1928, Flight C, Photograph 1 X: Scale: I inch = 1000 feet (approximate). San Diego County, 1960, Flight 3, Photographs 104 and 105; Scale: 1 inch = 1000 feet (approximate). San Diego County, 1970, Flight 3, Photographs 3 and 4; Scale: 1 inch = 1000 feet (approximate). San Diego County, 1975, Flight 35, Photographs 4 and 5; Scale: 1 inch =.1000 feet (approximate). San Diego County, 1978, Flight 15B, Photographs 32 and 33; Scale: 1 inch = 1000 feet (approximate). San Diego County, 1979, Flight 14B, Photographs 27 and 28; Scale: 1 inch = 1000 feet (approximate). 1 CWE 198.109 January 8, 1999 Appendix A, Page A3 I San Diego County, 1983, Photographs 245 and 246; Scale: 1 inch = 2000 feet (approximate). San Diego County, 1989, Photographs 3-3 and 3-5; Scale: 1 inch = 2000 feet (approximate). U.S. Department of Agriculture, 1953, Aerial Photographs, AXN-3M-31 & 32. I .... 1. 1 S I. S I. . I . I ..... S . I . S .. •1' 1 5S H • S CWE 198.109 January 8, 1999 Appendix B, Page BI PACIFIC SHORES NORTH RESIDENTIAL SUBDIVISION POINSETTIA LANE CARLSBAD, CALIFORNIA RECOMMENDED GRADING SPECIFICATIONS - GENERAL PROVISIONS GENERAL INTENT The intent of these specifications is to establish procedures for clearing, compacting natural ground, preparing areas to be filled, and placing and compacting fill soils to the lines and grades shown on the accepted plans. The recommendations contained in the preliminary geotechnical investigation report and/or the attached Special Provisions are a part of the Recommended Grading Specifications and shall supersede the provisions contained hereinafter in the case of conflict. These specifications shall only be used in conjunction with the geotechnical report for which they are a part. No deviation from these specifications will be allowed, except where specified in the geotechnical report or in other written communication signed by the Geotechnical Engineer. OBSERVATION AND TESTING Christian Wheeler Engineering shall be retained as the Geotechnical Engineer to observe and test the earthwork in accordance with these specifications. It will be necessary that the Geotechnical Engineer or his representative provide adequate observation so that he may provide his opinion as to whether or not the Work was accomplished as specified. It shall be the responsibility of the contractor to assist the Geotechnical Engineer and to keep him appraised of work schedules, changes and new information and data so that he may provide these opinions. In the event that any unusual conditions not covered by the special provisions or preliminary geotechnical report are encountered during the grading operations, the Geotechnical Engineer shall be contacted for further recommendations. If, in the opinion of the Geotechnical Engineer, substandard conditions are encountered, such as questionable or unsuitable soil, unacceptablemoisture content, inadequate compaction, adverse weather, etc., construction. should be stopped until the conditions are remedied or corrected or he shall recommend rejection of this work. Tests used to determine the degree of compaction should be performed in accordance with the following American Society for Testing and Materials test methods: CWE 198.109 January 8, 1999 Appendix B, Page B2 Maximum Density & Optimum Moisture Content - ASTM D-1557-91 Density of Soil In-Place - ASTM D-1556-90 or ASTM D-2922 All densities shall be expressed in terms of Relative Compaction as determined by the foregoing ASTM testing procedures; PREPARATION OF AREAS TO RECEIVE FILL All vegetation, brush and debris derived from clearing operations shall be removed, and legally disposed of. All areas disturbed by site grading should be left in a neat and finished appearance, free from unsightly debris. After clearing Or benching the natural ground, the areas to be filled shall be scarified to a depth of 12 inches, brought to the proper moisture content, compacted and tested for the specified minimum degree of compaction. All loose soils in excess of 6 inches thick should be removed to firm natural ground which is defined as natural soil which possesses an in-situ density of at least 90 percent of its maximum dry density. When the slope of the natural ground receiving fill exceeds 20 percent (5 horizontal units to I vertical unit), the original ground shall be stepped or benched. Benches 'Shall be cut to a firm competent formational soil. The lower bench shall be at least 10 feet wide or 1-1/2 times the equipment width, whichever is greater, and shall be sloped back into the hillside at a gradient of not less than two (2) percent. All other benches should be at least 6 feet wide. The horizontal portion of each bench shall be compacted prior to receiving fill as specified herein for compacted natural ground. Ground slopes flatter than 20 percent shall be benched when considered necessary by the Geotechnical Engineer. Although not anticipated, any abandoned buried structures encountered during grading operations must be totally removed. All underground utilities to be abandoned beneath any proposed structure should be removed from within 10 feet of the structure and properly capped off. The resulting depressions from the above described procedure should be backfllled with acceptable soil that is compacted to the requirements of the Geotechnical Engineer.. This includes, but is not limited to, septic tanks, fuel tanks, sewer lines or leach lines, storm drains and water lines. Any buried structures or utilities not to be abandoned should be brought to the attention of the Geotechnical Engineer so that he may determine if any special recommendation will be necessary. CWE 198.109 January 8, 1999 Appendix B, Page B3 FILL MATERIAL Materials to be placed in the fill shall be approved by the Geotechnical Engineer and shall be free of organic matter and other deleterious substances. Granular soil shall contain sufficient fine material to fill the voids. The. definition and disposition of oversized rocks and expansive or detrimental soils are covered in the geotechnical report or Special Provisions. Expansive soils, soils of poor gradation, or soils with low strength characteristics may be thoroughly mixed with other soils to provide satisfactory fill material, but only with the explicit consent of the Geotechnical Engineer. Any import material shall be approved by the Geotechnical Engineer before being brought to the site. PLACING AND COMPACTION OF FILL Approved fill material shall be placed in areasprepared to receive fill in layers not to exceed 6 inches in compacted thickness. Each layer shall have a uniform moisture content in the range that will allow the compaction effort to be efficiently applied to achieve the specified degree of-compaction. Each layer shall be uniformly compacted to the specified minimum degree of compaction with equipment of adequate size to economically compact the layer. Compaction equipment should either be specifically designed for so compaction or of proven reliability. The minimum- degree of compaction to be achieved is specified in either the Special Provisions or the recommendations contained in the preliminarygeotechnical investigation report. When the structural fill material includes rocks, no rocks will be allowed to nest and all voids must be carefully filled with soil such that the minimum degree of compaction recommended in the Special Provisions is achieved. The maximum size and spacing of rock permitted in structural fills and in non- structural fills is discussed in the geotechnical report, when applicable. Field observation and compaction. tests to estimate the degree of compaction of the fill will be taken by the Geotechnical Engineer or his representative. The location and frequency of the tests shall be at the Geotechnical Engineer's discretion. When the compaction test indicates that a particular layer is at less than the required degree of compaction, the layer shall be reworked to the satisfaction of the Geotechnical Engineer and until the desired relative compaction has been obtained. Fill slopes.shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction by sheepsfoot roller shall be at vertical intervals of not greater than four feet. In addition, fill slopes at a ratio of two horizontal to one vertical or flatter, should be trackrolled. Steeper fill slopes shall be over-built and cut- CWE 198.109 January 8, 1999 Appendix B, Page B4 back to fmish contours after the slope has been constructed. Slope compaction operations shall result in all fill material six or more inches inward from the finished face of the slope having a relative compaction of at least 90 percent of maximum dry density or the degree of compaction specified in the Special Provisions section of this specification. The compaction operation on the slopes shall be continued until the Geotechnical' Engineer is of the opinion that the slopes will be surficially stable. Density tests in the slopes will be made by the Geotechnical Engineer during construction of the slopes to determine if the required compaction is being achieved. Where failing tests occur or other field problems arise, the Contractor will be notified that day of such conditions by written communication from the Geotechnical Engineer or his representative in the form of a daily field report. If the method of achieving the required slope compaction selected by the Contractor fails to produce the necessary results, the Contractor shall rework or rebuild such slopes until the required degree of compaction is obtained, at no cost to the Owner or Geotechnical Engineer. CUT SLOPES The Engineering Geologist shall.-inspect cut slopes excavated in rock or lithified formational material during the grading operations at intervals determined at his discretion. If any conditions not anticipated in the preliminary report such as perched water, seepage, lenticular or confined strata of a potentially adverse nature, unfavorably inclined bedding, joints or fault planes are encountered during grading, these conditions shall be analyzed by the Engineering Geologist and Geotechnical Engineer to determine if mitigating measures are necessary. Unless otherwise specified in the geotechnical report, no cut slopes shall be excavated higher or steeper than that allowed by the ordinances of the controlling governmental agency. ENGINEERING OBSERVATION Field observation by the Geotechnical Engineer or his representative shall be made during the filling and compaction operations so that he can express his opinion regarding the conformance of the grading with acceptable standards of practice. Neither the presence of the Geotechnical Engineer or his representative or the observation and testing shall release the Grading Contractor from his duty to compact all fill material to the specified degree of compaction. CWE 198.109 S January 8, 1999 Appendix B, Page B5 SEASON LIMITS Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy rain, filling operations shall not be resumed until the proper moisture content and density of the fill materials can be achieved. Damaged site conditions resulting from weather or acts of God shall be repaired before acceptance of work. RECOMMENDED GRADING SPECIFICATIONS - SPECIAL PROVISIONS RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted natural - ground, compacted fill, and compacted backfill shall be at least 90 percent. For street and parking lot subgrade, the upper six inches should be compacted to atleast 95 percent relative compaction. EXPANSIVE SOILS: Detrimentally expansive soil is defined as clayey soil which has an expansion index of 50 or greater when tested in accordance with the Uniform Building Code Standard 29-C. OVERSIZED MATERIAL: Oversized fill material is generally defined herein as rocks or lumps of soil over 6 inches in diameter. Oversized materials should not be placed in fill unless recommendations of placement of such material are provided by the Geotechnical Engineer. At least 40 percent of the fill soils shall pass through a Na 4 U.S. Standard Sieve. I TRANSITION LOTS: Where transitions between cut and fill material falls within a lot, we recommend that the cut portion of the lot be over-excavated by a depth of three feet and said material replaced as uniformly I compacted flit Undercut areas should be sloped toward the fill area of the lot to prevent water that seeps into the ground from becoming perched above the natural soils. Lots with cut/fill transitions that will need to be I undercut should be identified by the project geologist during grading.