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HomeMy WebLinkAboutMS 07-01; HAIG/SCOTT SUBDIVISION; REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION; 2006-07-03454 Geotechnical Exploration, Inc. SOIL AND FOUNDATION GROUNDWATER ENGINEEFdNG GEOLOGY 03 July 2006 0 Mr. Michael Haig Job No. 06-9232 Mr. Thomas Scott 5233 Los Robles Carlsbad, CA 92008 Subject: Report of Preliminary Geotechnical Investigation Haig/Scott Property 3320 Highland Drive Carlsbad, California Gentlemen: In accordance with your request, and our proposal of June 6, 2006, Geotechnical Exploration, Inc. has performed a preliminary geotechnical investigation for the subject property. The fieldwork was performed on June 19, 2006. If the conclusions and recommendations presented in this report are incorporated into the design and construction of the proposed residences, it is our opinion that the site is suitable for the project. This opportunity to be of service is sincerely appreciated. Should you have any questions concerning the following report, please do not hesitate to contact us. Reference to our Job No. 06-9232 will expedite a response to your inquiries. Respectfully submitted, GEOTECHNICAL EXPLORATION, INC. Jai os, P.E. ( R.C.E. 344221G.E Senior LAJ (( No. 009 )) cr_\Exp. 4L 0 VO7jJ* oFCP&J' )H ise~~~ eiser Senior Project Geologist 7420 TRADE STREETS SAN • (858) 549-72221 FAX: (858) 549-1604' EMAIL:geoWch@bcpres.com I TABLE OF CONTENTS I PAGE I. PROJECT SUMMARY AND SCOPE OF SERVICES 1 - II. SITE DESCRIPTION 1 I III. FIELD INVESTIGATION 2 1 IV. SOIL DESCRIPTION 3 V GROUNDWATER 3 I VI. SEISMIC CONSIDERATIONS 4 I VII. LABORATORY TESTS AND SOIL INFORMATION 5 VIII. CONCLUSION AND RECOMMENDATIONS 6 I IX. GRADING NOTES 18 I X. LIMITATIONS 19 I FIGURES Vicinity Map I Site Plan IIIa-e. Exploratory Logs IV. Foundation Requirements Near Slopes APPENDICES I A. Unified Soil Classification System 1 fl I LLAJ I I I REPORT OF PRELIMINARY GEOTECHNICAL INVESTIGATION Haig/Scott Property I 3320 Highland Drive Carlsbad, California Job No. 06-9232 I The following report presents the findings and recommendations of Geotechnical Exploration, Inc. for the subject site (for project location see Figure No. I). I. PROJECT SUMMARY AND SCOPE OF SERVICES It is our understanding the subject residential property (APN 205-060-06) is to be I subdivided into two parcels. Parcel A is occupied by an existing residence and a new residence will be constructed on Parcel B. Final plans may also include a new I residence on Parcel A. Although plans are not available, we anticipate the proposed new residences will be one and/or two-story structures with slab-on-grade floors. Foundation loads are expected to be typical for this type of relatively light construction. I The scope of work performed for this investigation included a site reconnaissance I and subsurface exploration program, laboratory testing, geologic and engineering analysis of the field and laboratory data, and the preparation of this report. The I data obtained and the analyses performed were for the purpose of providing design and construction criteria for the project earthwork, building foundations, and slab- on-grade floors. I II. SITE DESCRIPTION I The subject property is a roughly rectangular shaped lot with a plan area of about 3/4-acre. The proposed Parcel A, which is occupied by an existing residence, a I detached garage and associated improvements, has been previously graded to a IMS Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 2 pad elevation of about 180 feet above mean sea level (MSL) with a 5-foot-high, 2.0 horizontal to 1.0 vertical cut slope along the western boundary adjacent to Highland Drive. The area of proposed Parcel B is a gently sloping naturall area with elevations varying from approximately 178 feet above MSL in the middle of the property to approximately 168 feet above MSL at the east end of the property. I Vegetation on the proposed Parcel B consists of native grass and shrubs with a few ornamental trees. Underground utilities appear to enter the property from the west I property boundary along Highland Drive. A small storage shed is present in the southwest portion of Parcel B. III. FIELD INVESTIGATION The field investigation consisted of a surface reconnaissance and a subsurface exploration program utilizing hand tools. Five exploratory test pits were excavated across Parcels A and B on June 19, 2006, to a depth of 2 feet. The soils encountered in the test pits were continuously logged in the field by our representative and described in accordance with the Unified Soil Classification System (Refer to Appendix A); The approximate locations of the test pits are shown on Figure No. II. Representative samples were obtained from the exploratory test pits at selected depths appropriate to the investigation. All samples were returned to our laboratory for evaluation and testing. Exploratory test pit logs have been prepared on the basis of our observations and laboratory test results. Logs of the test pits are attached as Figure No. III. Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 3 IV. SOIL DESCRIPTION Artificial fill and/or topsoils consisting of dry, loose to medium dense, silty sands were encountered in all the test pits to a depth of 18 inches. The fill/topsoils were underlain by terrace formational materials consisting of medium dense silty sands, to the maximum depths explored. V. GROUNDWATER Free groundwater was not encountered in the exploratory test pits at the time of excavation. It must be noted, however, that fluctuations in the level of groundwater may occur due to variations in ground surface topography, subsurface stratification, rainfall, and other possible factors that may not have been evident at the time of our field investigation. It should be kept in mind that grading operations can change surface drainage patterns and/or reduce permeabilities due to the densification of compacted soils. Such changes of surface and subsurface hydrologic conditions, plus irrigation of landscaping or significant increases in rainfall, may result in the appearance of surface or near-surface water at locations where none existed previously. The appearance of such water is expected to be localized and cosmetic in nature, if good positive drainage is implemented, as recommended in this report, during and at the completion of construction. It must be understood that unless discovered during initial site exploration or encountered during site grading operations, it is extremely difficult to predict if or where perched or true groundwater conditions may appear in the future. When site fill or formational soils are fine-grained and of low permeability, water problems may not become apparent for extended periods of time. Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 4 I I Water conditions, where suspected or encountered during construction, should be evaluated and remedied by the project civil and geotechnical consultants. The I project developer and property owner, however, must realize that post-construction appearances of groundwater may have to be dealt with on a site-specific basis. I VI. SEISMIC CONSIDERATIONS 1 The San Diego area, as most of California, is located in a seismically active region. I The San Diego area has been referred to as the eastern edge of the Southern California Continental Borderland, an extension of the Peninsular Ranges I Geomorphic Province. The borderland is part of a broad tectonic boundary between the North American and Pacific Plates. The plate boundary is dominated by a I complex system of active major strike-slip (right lateral), northwest trending faults extending from the San Andreas fault, about 70 miles east, to the San Clemente I fault, about 50 miles west of the San Diego metropolitan area. Based on our review of some available published information including County of San Diego Faults and Epicenters Map, there are no faults known to pass through the site. The prominent fault zones generally considered having the most potential for earthquake damage in the vicinity of the site are the active Rose Canyon and Coronado Bank fault zones mapped approximately 8 and 17 miles west of the site, respectively, and the active Elsinore and San Jacinto fault zones mapped approximately 27 and 48 miles northeast of the site, respectively. Although research on earthquake prediction has greatly increased in recent years, geologists and seismologists have not yet reached the point where they can predict when and where an earthquake will occur. Nevertheless, on the basis of current technology, it is reasonable to assume that the proposed residences may be subject to the effects of at least one moderate to major earthquake during their design life. i IJ L L I I I' I [ I Haig/Scot Property Job No. 06-9232 Carlsbad, California Page 5 I During such an earthquake, the danger from fault offset through the site is remote, but relatively strong ground shaking is likely to occur. Based on the encountered I soil conditions, it is our opinion that the potential for soil liquefaction and/or soil strength loss is negligible. I VII. LABORATORY TESTS AND SOIL INFORMATION I Laboratory tests were performed on disturbed and relatively undisturbed soil I samples in order to evaluate their index, strength, expansion, and compressibility properties. The following tests were conducted on the sampled soils and the results I are presented on the test pit logs: Laboratory Compaction Characteristics (ASTM D1557-98) Determination of Percentage of Particles Passing #200 (ASTM D1140) Laboratory compaction tests establish the laboratory maximum dry density and optimum moisture content of the tested soils. This test was used to aid in evaluating the existing soils at the site with regard to their reuse as compacted structural fill. The particle size smaller than a No. 200 sieve analysis tests aid in classifying the soils in accordance with the Unified Soil Classification System and provide qualitative information related to engineering characteristics such as expansion potential, permeability, and shear strength. Based on the laboratory test results and our past experience with similar materials, it is our opinion that the fill/topsoils and terrace formational materials encountered have a low potential for expansion. I I Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 6 I I VIII. CONCLUSIONS AND RECOMMENDATIONS From a geotechnical engineering standpoint, it is our opinion that the site is suitable for construction of proposed new residences on Parcels A and B provided the conclusions and recommendations presented in this report are incorporated into their design and construction. The primary feature of concern at the site is the presence of potentially I compressible loose fill/topsoils extending to a depth of 18 inches. In order to preclude the possibility of the proposed residences and other improvements being I subject to excessive total and differential settlements resulting from compression of the loose fill/topsoils, we recommend that all loose fill/topsoils supporting structural and exterior improvements be removed to at least 5 feet beyond the perimeter. I Detailed earthwork and foundation recommendations are presented in the following paragraphs. The opinions, conclusions, and recommendations presented in this 1 report are contingent upon Geotechnical Exploration, Inc. being retained to review the final plans and specifications as they are developed and to observe the I site earthwork and installation of foundations. A. Preparation of Soils for Site DeveloDment 1. Clearing and Stripping: The area of proposed construction should be cleared of any structures or miscellaneous debris that may be present at the time of I construction. After clearing, the ground surface should be stripped of surface vegetation as well as associated root systems. Holes resulting from the removal of buried obstructions that extend below the proposed finished site grades should be cleared and backfiUed with suitable material compacted to I -' Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 7 I the requirements given under Recommendation No. 6, "Compaction." The cleared and stripped materials should be properly disposed of off-site. 2. Excavation: Excavation refusal was not encountered during our site I investigation. We anticipate that excavations extending to the proposed pad elevations will be able to be accomplished with conventional grading I equipment such as a D-6 Caterpillar tractor or equivalent. I 3. Treatment of Loose Fill/Topsoils: In order to provide suitable foundation support for the proposed residences and other improvements, we recommend that all loose fill and/or topsoils that remain after the necessary site excavations have been made be removed and recompacted. The areal I extent and depth required to remove the loose fill and/or topsoils should be determined by our representatives during the excavation work based on their I examination of the soils being exposed. Any unsuitable materials (such as oversize rubble and/or organic matter) should be selectively removed as I directed by our representative and disposed of off-site. In no case should the lateral extent of soil removal be less than 5 feet beyond the perimeter of I proposed structures. I Any rigid improvements founded on the existing loose surface soils can be expected to undergo movement and possible damage. Geotechnical I Exploration, Inc. takes no responsibility for the performance of any improvements buit on loose surface soils and/or inadequately compacted fills. Any exterior area to receive concrete improvements should be verified for compaction and moisture within 48 hours prior to concrete placement. 4. Subgrade Preparation: After the site has been cleared, stripped, and the I required excavations made, the exposed subgrade soils in those areas to I L Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 8 I receive fill or huilding improvements (including any exterior flatwork or pavement areas) should be scarified to a depth of 6 inches, moisture I conditioned, and compacted to the requirements of Recommendation No. 6, "Compaction." I Fills constructed on sloping ground having an inclination steeper than 6.0:1.0 I (horizontal to vertical) should be keyed and benched into competent formational material below any loose natural soils. The actual width of the I toe keys and extent of removal of any existing loose surface soil or weathered formational materials should be determined by our representative I in the field during construction. In addition, toe key excavations should be inspected by our representative prior to placing fill. Materials for Fill: All on-site soils with an organic content of less than 3 percent by volume are in general suitable for reuse as fill. Fill material should not, however, contain rocks or lumps over 6 inches in greatest dimension and not more than 15 percent larger than 21/2 inches. Proposed imported soils should be evaluated and approved by our firm prior to importing to the site. Compaction: All structural fill and backfill should be compacted to a I minimum degree of compaction of 90 percent at or above the optimum moisture content based upon ASTM Test Designation D1557-91. Fill material I should be spread and compacted in uniform horizontal lifts not exceeding 8 inches in uncompacted thickness. Before compaction begins, the fill should I be brought to a water content that will permit proper compaction by either: 1) aerating the fill if it is too wet, or 2) moistening the fill with water if it is I too dry. Each lift should be thoroughly mixed before compaction to ensure a uniform distribution of moisture. I Haig/Scott Property Job No. 06-9232 I Carlsbad, California Page 9 I 7. Permanent Slope We recommend that any required cut or fill slopes be constructed to an inclination no steeper than 2 to 1 (horizontal to vertical). I The project plans and specifications should contain all necessary design features and construction requirements to prevent erosion of the on-site soils I both during and after construction. Slopes and other exposed ground surfaces should be appropriately planted with a protective ground cover. I Fill slopes should be constructed to assure that the recommended minimum U degree of compaction is attained out to the finished slope face. This may be accomplished by "backrolling" with a sheepsfoot roller or other suitable I equipment as the fill is raised. Placement of fill near the tops of slopes should be carried out in such a manner as to assure that loose, uncompacted I soils are not sloughed over the tops and allowed to accumulate on the slope face. I Trench Backfill: All pipeline trenches should be backfilled with compacted fill. Backfill material should be placed in lift thicknesses appropriate to the type of compaction equipment utilized and compacted to a minimum degree of compaction of 90 percent by mechanical means. Our experience has shown that even shallow, narrow trenches, such as for irrigation and electrical lines, which are not properly compacted, can result in problems, particularly with respect to shallow groundwater accumulation and migration. Drainage: Positive surface gradients should be provided adjacent to the residences, and roof gutters and downspouts should be installed to direct water away from foundations and slabs toward suitable discharge facilities. LLAJJ - Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 10 residences or or pavements. Sufficient and effective working drains should be installed around the residence and in areas where water runoff may be encountered. I B. Design Parameters for ProDosed Foundations I 10. Proposed Footings: We recommend that the proposed residences be supported on conventional, individual-spread and/or continuous footing I foundations bearing on undisturbed formational material and/or properly compacted fill material. All footings should be founded at least 18 inches I below the lowest adjacent finished grade or 12 inches into dense, terrace formational materials, whichever is less. I At the recommended depths, footings may be designed for allowable bearing I pressures of 2,000 pounds per square foot (psf) for combined dead and live loads and 2,700 psf for all loads, including wind or seismic. The footings I should, however, have a minimum width of 12 inches. 11. General Criteria For All Footings: Footings located adjacent to the tops of slopes or on sloping natural ground should be extended sufficiently deep so as to provide at least 8 feet of horizontal cover or 11/2 times the width of the footing, whichever is greater, between the slope face and outside edge of the footing at the footing bearing level. Footings located adjacent to utility trenches should have their bearing surfaces situated below an imaginary 1.5 to 1.0 plane projected upward from the bottom edge of the adjacent utility trench (see Figure No. IV). All continuous footings should contain top and bottom reinforcement to provide structural continuity and to permit spanning of local irregularities. [ U I I p I I Haig/Scott Property Carlsbad, California I Job No. 06-9232 Page 11 We recommend that a minimum of two No. 5 top and two No. 5 bottom reinforcing bars be provided in the footings. A minimum clearance of 3 inches should be maintained between steel reinforcement and the bottom or sides of the footing. In order for us to offer an opinion as to whether the footings are founded on soils of sufficient load bearing capacity, it is essential that our representative inspect the footing excavations prior to the placement of reinforcing steel or concrete. NOTE: The project Civil/Structural Engineer should review all reinforcing schedules. The reinforcing minimums recommended herein are not to be construed as structural designs, but merely as minimum reinforcement to reduce the potential for cracking and separations. 12. Seismic Design Criteria: Site-specific seismic design criteria to calculate the base shear needed for the design of the proposed structures are presented in the following table. The design criteria was obtained from the California Building Code (2001 edition) and is based on the distance to the closest active fault and soil profile classification. The nearest active fault zone is mapped approximately 14 kilometers (approximately 9 miles) to the west of the project site. Parameter Value Reference Seismic Zone Factor, Z 0.40 Table 16-I Soil Profile Type Sc Table 16-3 Seismic Coefficient, Ca 0.40Na Table 16-Q Seismic Coefficient, Cv 0.56Nv Table 16-R Near-Source Factor, Na 1.0 Table 16-S I Near-Source Factor, N 1.0 Table 16-T LSeismic Source Type B Table 16-U I I I Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 12 Lateral Loads: Lateral load resistance for the residences supported on footing foundations may be developed in friction between the foundation bottoms and the supporting subgrade. An allowable friction coefficient of 0.40 is considered applicable. An additional allowable passive resistance equal to an equivalent fluid weight of 275 pounds per cubic foot acting against the foundations may be used in design provided the footings are poured neat against the adjacent undisturbed granitic materials and/or compacted fill materials. These lateral resistance values assume a level surface in front of the footing for a minimum distance of three times the embedment depth of the footing and any shear keys. Settlement: Settlement under building loads is expected to be within tolerable limits for the proposed residences. For footings designed in accordance with the recommendations presented in the preceding paragraphs, we anticipate that total settlements should not exceed 1 inch and that post-construction differential angular rotation should be less than 1 inch in 25 feet. Conventional Masonry Block Retaining Walls: Conventional masonry block retaining walls must be designed to resist lateral earth pressures and any additional lateral pressures caused by surcharge loads on the adjoining retained surface. We recommend that unrestrained (cantilever) walls with level backfill be designed for an equivalent fluid pressure of 38 pounds per cubic foot (pcf). We recommend that restrained walls (i.e., any walls with angle points that restrain them from rotation) with level backfill be designed for an equivalent fluid pressure of 38 pcf plus an additional uniform lateral pressure of 8xH pounds per square foot where H is equal to the height of backfill above the top of the wall footing in feet. For sloping 2.0:1.0 backfill, we recommend an active soil pressure of 52 pcf. I I I1 LI U - Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 13 The preceding desjn pressures assume that the walls are backfihled w i t h l o w expansion potential on-site or imported materials and that there is su f f i c i e n t drainage behind the walls to prevent the build-up of hydrostatic pre s s u r e s from surface water infiltration. We recommend that drainage be p r o v i d e d b y a composite drainage material such as Miradrain 6000/6200 or e q u i v a l e n t . The drain material should terminate 12 inches below the finish surfac e . T h e waterproofing should end 6 inches above the ground surface. Backfill placed behind the walls should be compacted to a min i m u m o f 9 0 percent using light compaction equipment in areas close to the w a l l s a n d heavy equipment in areas outside a 45-degree angle plane drawn f r o m t h e bottom of the wall stem. Retaining walls should be supported on footing foundations des i g n e d i n accordance with the recommendations presented previous l y u n d e r Recommendation Nos. 10 and 11. Lateral load resistance for the w a l l s c a n be developed in accordance with the recommendations present e d u n d e r Recommendation No. 13 "Lateral Loads." C. Concrete Slab-on-grade Criteria 16. Minimum Floor Slab Reinforcement: Based on our experience, we have found that, for various reasons, floor slabs occasionally crack, causin g b r i t t l e surfaces such as ceramic tiles to become damaged. Therefore, we recommend that all slabs-on-grade contain at least a minimum a m o u n t o f reinforcing steel to reduce the separation of cracks, should they o c c u r . 16.1 Interior floor slabs should be a minimum of 4 inches actual t h i c k n e s s and be reinforced with No. 3 bars on 18-inch centers, both ways , Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 14 1 placed at midheight in the slab. The slabs should be underlain by a 2- inch-thick layer of clean sand (S.E. = 50 or greater) overlying a I moisture retardant membrane over 2 inches of clean sand. Slab subgrade soil should be verified by a Geotechnical Exploration, Inc., I representative to have the proper moisture content within 48 hours prior to placement of the vapor barrier and pouring of concrete. 1. 16.2 Following placement of any concrete floor slabs, sufficient drying time I must be allowed prior to placement of floor coverings. Premature placement of floor coverings may result in degradation of adhesive I materials and loosening of the finish floor materials. 1 17. Concrete Isolation Joints: We recommend the project Civil/Structural Engineer incorporate isolation joints and sawcuts to at least one-fourth the I thickness of the slab in any floor designs. The joints and cuts, if properly placed, should reduce the potential for and help control floor slab cracking. I We recommend that concrete shrinkage joints be spaced no farther than approximately 20 feet apart, and also at re-entrant corners. However, due to a number of reasons (such as base preparation, construction techniques, curing procedures, and normal shrinkage of concrete), some cracking of slabs can be expected. 1 18. Slab Moisture Emission: Soil moisture vapor can result in damage to moisture-sensitive floors, some floor sealers, or sensitive equipment in direct I contact with the floor, in addition to mold and staining on slabs, walls and carpets. I The common practice in Southern California is to place vapor retarders made I of PVC, or of polyethylene. PVC retarders are made in thickness ranging - Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 15 1 from 10- to 60-mu. Polyethylene retarders, called visqueen, range from 5- to 10-mil in thickness. The thicker the plastic, the stronger the resistance will I be against puncturing. I Although polyethylene (visqueen) products are commonly used, products such as Vaporshield possess higher tensile strength and are more specifically I designed for and intended to retard moisture transmission into concrete slabs. The use of Vaporshield or equivalent is highly recommended when a I structure is intended for moisture-sensitive floor coverings or uses. 1 18.1 Vapor retarder joints must be lapped and sealed with mastic or the manufacturer's recommended tape. To provide protection of the I moisture retarder, a layer of at least 2 inches of clean sand on top and 2 inches at the bottom should also be provided. No heavy equipment, I stakes or other puncturing instruments should be used on top of the liner before or during concrete placement. In actual practice, stakes I are often driven through the retarder material, equipment is dragged or rolled across the retarder, overlapping or jointing is not properly I implemented, etc All these construction deficiencies reduce the retarder's effectiveness. I 18.2 The vapor retarders are not waterproof. They are intended to help I prevent or reduce vapor transmission and capillary migration through the soil into the pores of concrete slabs. Waterproofing systems must I supplement vapor retarders if full waterproofing is desired. The owner should be consulted to determine the specific level of protection I required. 9 J Haig/ Scott Property Job No. 06-9232 Carlsbad, California Page 16 Exterior Slab Reir.rcement: As a minimum for protection of on-site improvements, we recommend that all exterior pedestrian concre t e s l a b s b e 4 inches thick, founded on properly compacted and tested fill a n d / o r d e n s e undisturbed granitic materials, with No. 3 bars at 18-inch centers, b o t h w a y s , at the center of the slab, and contain adequate isolation and cont r o l j o i n t s . The performance of on-site improvements can be greatly af f e c t e d b y s o i l base preparation and the quality of construction. It is therefore i m p o r t a n t that all improvements are properly designed and constructed for the e x i s t i n g soil conditions. The improvements should not be built on loose s o i l s o r f i l l s placed without our observation and testing. For exterior slabs with the minimum shrinkage reinforcement , c o n t r o l j o i n t s should be placed at spaces no farther than 15 feet apart or the w i d t h o f t h e slab, whichever is less, and also at re-entrant corners. Control j o i n t s i n exterior slabs should be sealed with elastomeric joint sealant. Th e s e a l a n t should be inspected every 6 months and be properly maintained . D. SloDe Performance Slope ToD/Face Performance: The soils that occur in close proximity to the top or face of even properly compacted fill or dense natural gro u n d c u t s l o p e s often possess poor lateral stability. The degree of lateral an d v e r t i c a l deformation depends on the inherent expansion and strength charac t e r i s t i c s of the soil types comprising the slope, slope steepness and height, l o o s e n i n g of slope face soils by burrowing rodents, and irrigation and veg e t a t i o n maintenance practices, as well as the quality of compaction of f i l l s o i l s . Structures and other improvements could suffer damage due to t h e s e s o i l movement factors if not properly designed to accommodate or w i t h s t a n d such movement. Haig/Scott Property Carlsbad, California Job No. 06-9232 Page 17 Slope Top Structure Performance: Rigid improvements such as top-of-slope walls, columns, decorative planters, concrete flatwork, and other similar types of improvements can be expected to display varying degrees of separation typical of improvements constructed at the top of a slope. The separations result primarily from slope top lateral and vertical soil deformation processes. These separations often occur regardless of being underlain by cut or fill slope material. Proximity to a slope top is often the primary factor affecting the degree of separations occurring. Typical and to-be-expected separations can range from minimal to up to 1 inch or greater in width. In order to minimize the effect of slope-top lateral soil deformation, we recommend that the top-of-slope improvements be designed with flexible connections and joints in rigid structures so that the separations do not result in visually apparent cracking damage and/or can be cosmetically dressed as part of the ongoing property maintenance. These flexible connections may include "slip joints" in wrought iron fencing, evenly spaced vertical joints in block walls or fences, control joints with flexible caulking in exterior flatwork improvements, etc. E. General Recommendations Project Start Up Notification: In order to minimize any work delays during site development, this firm should be contacted 24 hours prior to any need for observation of footing excavations or field density testing of compacted fill soils. If possible, placement of formwork and steel reinforcement in footing excavations should not occur prior to observing the excavations; in the event that our observations reveal the need for deepening or redesigning foundation structures at any locations, any formwork or steel reinforcement in the affected footing excavation areas would have to be removed prior to 111 I L I - Haig!Scott Property Job No. 06-9232 Carlsbad, California Page 18 correction of the observed problem (i.e., deepening the footing excavation, recompacting soil in the bottom of the excavation, etc.) 23. Construction Best Management Practices (BMPs): Sufficient BMPs must be installed to prevent silt, mud or other construction debris from being tracked into the adjacent street(s) or storm water conveyance systems due to construction vehicles or any other construction activity. The contractor is responsible for cleaning any such debris that may be in the street at the end of each work day or after a storm event that causes breach in the installed construction BMPs. All stockpiles of uncompacted soil and/or building materials that are intended to be left unprotected for a period greater than 7 days are to be provided with erosion and sediment controls. Such soil must be protected each day when the probability of rain is 40% or greater. A concrete washout should be provided on all projects that propose the construction of any concrete improvements that are to be poured in place. All erosion/sediment control devices should be maintained in working order at all times. All slopes that are created or disturbed by construction activity must be protected against erosion and sediment transport at all times. The storage of all construction materials and equipment must be protected against any potential release of pollutants into the environment. IX. GRADING NOTES Geotechnical Exploration, Inc. recommends that we be retained to verify the actual soil conditions revealed during site grading work and footing excavation to be as anticipated in this "Report of Preliminary Geotechnical Investigation" for the project. In addition, the compaction of any fill soils placed during site grading work must be observed and tested by the soil engineer. It is the responsibility of the grading contractor to comply with the requirements on the grading plans and the Haig/Scott Property Job No. 06-9232 Carlsbad, California Page 19 I I local grading ordinance as well as with our recommendations included in this report. All fill retaining wall and trench backfill should be properly compacted. I Geotechnical Exploration, Inc. will assume no liability for damage occurring due to improperly or uncompacted backfill placed without our observations and testing. X. LIMITATIONS 1 Our conclusions and recommendations have been based on available data obtained I from our field investigation and laboratory analysis, as well as our experience with similar soils and formational materials located in this area of San Diego County. Of I necessity, we must assume a certain degree of continuity between exploratory excavations. It is, therefore, necessary that all observations, conclusions, and I recommendations be verified at the time grading operations begin or when footing excavations are placed. In the event discrepancies are noted, additional I recommendations may be issued, if required. U The work performed and recommendations presented herein are the result of an investigation and analysis that meet the contemporary standard of care in our I profession within the County of San Diego. No warranty is provided. I This report should be considered valid for a period of two (2) years, and is subject to review by our firm following that time. If significant modifications are made to I the building plans, especially with respect to the height and location of any proposed structures, this report must be presented to us for immediate review and I possible revision. It is the responsibility of the owner and/or developer to ensure that the recommendations summarized in this report are carried out in the field operations [ and that our recommendations for design of this project are incorporated in the I I I Haig/Scott Property Job No. 06-9232 I Carlsbad, California Page 20 I structural plans. We should be retained to review the project plans once they are available, to see that our recommendations are adequately incorporated in the I plans. I This firm does not practice or consult in the field of safety engineering. We do not direct the contractor's operations, and we cannot be responsible for the safety of I personnel other than our own on the site; the safety of others is the responsibility of the contractor. The contractor should notify the owner if he considered any of I the recommended actions presented herein to be unsafe. I The firm of Geotechnical Exploration, Inc. shall not be held responsible for changes to the physical condition of the property, such as addition of fill soils or I changing drainage patterns, which occur subsequent to issuance of this report and the changes are made without our observations, testing, and approval. I Once again, should any questions arise concerning this report, please feel free to I contact the undersigned. Reference to our Job No. 06-9232 will expedite a reply to your inquiries. I Respectfully submitted, I GEOTECHNICAL EXPLORATION, INC. 7 R.C.E. 34422/G.E. 2007 I Senior Geotechnical Engine . Jay K. neiser Senior Project Geologist I I EQ(JIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED Hand Tools 2'X 2'X 2' Handplt 6-19-06 SURFACE ELEVATION GROUNDWATER! SEEPAGE DEPTH LOGGED BY ± 178' Mean Sea Level Not Encountered JKH - - - FIELD DESCRIPTION AND CLASSIFICATION w + 0 co -J ° -- DESCRIPTION AND REMARKS vs (Grain size, Density, Moisture, Color) u$ Or °r 0. Z 8 o 8 Q Q W U) - SILTY SAND, fine- to medium-grained, with 79M - some roots and rock fragments. Loose. Dry. Gray-brown. - FILL! TOPSOIL (Oaf) 14 Ell SILTY SAND, fine- to medium-grained; well SM cemented. Medium dense. Damp. Red-brown. TERRACE DEPOSITS (Qt) - 2 Bottom of excavation @ 2' Y'. PERCHED WATER TABLE JOB NAME Haig! Scott Property SITE LOCATION LOOSE BAG SAMPLE IN-PLACE SAMPLE 3320 Highland Drive, Carlsbad, CA JOB NUMBER REVIEWED BY JAC j LOG No. DRIVE SAMPLE J FIELD DENSITY TEST 06-9232 FIGURE NUMBER HP-1 G.otclmlcal raon. IflC STANDARD PENETRATION TEST lila EQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED Hand Tools 2'X 2'X 2' Handplt 6-19-06 SURFACE ELEVATION GROUNDWATER/ SEEPAGE DEPTH LOGGED BY ± 179' Mean Sea Level Not Encountered JKH FIELD DESCRIPTION AND • CLASSIFICATION DESCRIPTION AND REMARKS w (Grain size, Density, Moisture, Color) - SILTY SAND fine- to medium-grained, with SM some roots and rock fragments. Loose. Dry. - Gray-brown. - FILL! - TOPSOIL (Qaf) - SILTY SAND, fine- to medium-grained; SM - moderately well cemented. Medium dense. Damp. Red-brown. 2- TERRACE DEPOSITS (Qt) Bottom of excavation @ 2' 3- 4- Y. PERCHED WATER TABLE JOB NAME Haig/ Scott Property SITE LOCATION LOOSE BAG SAMPLE 5-1 IN-PLACE SAMPLE 3320 Highland Drive, Carlsbad, CA JOB NUMBER REVIEWED BY JAC LOG No. 8 DRIVE SAMPLE FIELD DENSITY TEST 06-9232 HP=2 Geot.dentc.I Iq EXP1OIO1I. Inc. STANDARD PENETRATION TEST FIGURE NUMBER lllb EQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED Hand Tools 2'X 2' X 2' Handplt 6-19-06 SURFACE ELEVATION GROUNDWATER! SEEPAGE DEPTH LOGGED BY ± 177' Mean Sea Level Not Encountered JKH FIELD DESCRIPTION AND ze CLASSIFICATION DESCRIPTION AND REMARKS LU (Grain se, Density, Moisture, Color) z Z13 - SILTY SANQ fine- to medium-grained, with SM some roots and rock fragments. Loose: Dry. Gray-brown. FILL! TOPSOIL (Oaf) 1- SILTY SAND, fine- to medium-grained; well SM - cemented. Medium dense. Damp. Red-brown. TERRACE DEPOSITS (Qt) - 2 Bottom of excavation @ 2' 3- 4- I PERCHED WATER TABLE JOB NAME Haig/ Scott Property LOOSE BAG SAMPLE SITE LOCATION I [3] IN-PLACE SAMPLE 3320 Highland Drive, Carlsbad, CA • DRIVE SAMPLE JOB NUMBER REVIEWED BY JAC LOG No. I 3] FIELD DENSITY TEST 06-9232 Geotechnkal EW11oradon, Inc. HP=3 STANDARD PENETRATION TEST FIGURE NUMBER I EQUIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED Hand Tools 2'X 2' X 2' Handplt 6-19-06 SURFACE ELEVATION GROUNDWATER! SEEPAGE DEPTH LOGGED BY ± 174' Mean Sea Level Not Encountered JKH - - - FIELD DESCRIPTION AND 2 CLASSIFICATION . DESCRIPTION AND REMARKS -;;_ ° 9 w >.. Density, Moisture, Color) (Grain size, - - SILTY SANQ fine- to medium-grained, with SM ' some roots and rock fragments. Loose. Dry. . Gray-brown. - FILL! - TOPSOIL (Qaf) - SILTY SANQ fine- to medium-grained; - moderately well cemented. Medium dense. Damp. Red-brown. 2 -A TERRACE DEPOSITS - Bottom of excavation @ 2' 3- 4- C. Y PERCHED WATER TABLE JOB NAME Haig! Scott Property SITE LOCATION LOOSE BAG SAMPLE rn IN-PLACE SAMPLE 3320 Highland Drive, Carlsbad, CA JOB NUMBER i REVIEWED BY JAC LOG No. 1 8 DRIVE SAMPLE Fs FIELD DENSITY TEST 06-9232 HP=4 Expioradon, kK. FIGURE NUMBER MW PENETRATION TEST 11111dSTANDARD 'ia(JIPMENT DIMENSION & TYPE OF EXCAVATION DATE LOGGED Hand Tools 2' X 2'X 2' Handplt 6-19-06 SURFACE ELEVATION GROUNDWATER! SEEPAGE DEPTH LOGGED BY 1169' Mean Sea Level Not Encountered JKH FIELD DESCRIPTION AND • CLASSIFICATION DESCRIPTION AND REMARKS (Grain se, Density, Moisture, Color) 9 - - SILTY SANfl fine- to medium-grained, with SM some roots and rock fragments. Loose. Dry. • Gray-brown. - FILL! TOPSOIL (Qaf) 1T SILTY SANIR fine- to medium-grained; well SM - cemented. Medium dense. Damp. Red-brown. TERRACE DEPOSITS (Qt) - 2 Bottom of excavation © 2' 3- 4- PERCHED WATER TABLE JOB NAAE Haig! Scott Property SITE LOCATION LOOSE BAG SAMPLE E1 IN-PLACE SAMPLE 3320 Highland Drive, Carlsbad, CA JOB NUMBER REVIEWED BY JAC LOG No. DRIVE SAMPLE Fs-1 FIELD DENSITY TEST 06-9232 FIGURE NUMBER HP=5 Gechnkal ro . Ille STANDARD PENETRATION TEST E, 2a uO I FOUNDATION REQUIREMENTS NEAR SLOPES Proposed Structure Concrete Floor Slab Setback TOP OF COMPACTED FILL SLOPE (Any loose soils on the slope surface shall not be considered to provide lateral or vertical strength for the footing or for slope stability. Needed depth of imbedment shall be measured from competent soil.) COMPACTED FILL SLOPE WITH MAXIMUM INCLINATION AS PER SOILS REPORT. Reinforcement of Foundations and Floor Slabs Following the Recommendations of the s - Architect or Structural k •' s... Engineer. Concrete Foundation 18" Minimum or as Deep as Required for Lateral Stability Total Depth of Footing Measured from Finish Soil Sub-Grade I COMPACTED FILL Outer Most Facè'.. of Footing TYPICAL SECTION (Showing Proposed Foundation Located Within 8 Feet of Top of Slope) 18" FOOTING /8' SETBACK Total Depth of Footing 1.5:1.0 SLOPE 2.0:1.0 SLOPE 0 82" 66" 2' 66" 54" 41 51" 47' 6' 34" 30" 8' 18" 18" # when applicable Figure No. IV Job No. 06-9232 SHW 0 Geotechnical ___ Exploration, Inc. APPENDIX A UNIFIED SOIL CLASSIFICATION CHART SOIL DESCRIPTION Coarse-grained (More than half of material is larger than a No. 200 sieve) GRAVELS, CLEAN GRAVELS GW Well-graded gravels, gravel and sand mixtures, little (More than half of coarse fraction or no fines. is larger than No. 4 sieve size, but smaller than 3") GP Poorly graded gravels, gravel and sand mixtures, little or no fines. GC Clay gravels, poorly graded gravel-sand-silt mixtures SW Well-graded sand, gravelly sands, little or no fines SP Poorly graded sands, gravelly sands, little or no fines. SM Silty sands, poorly graded sand and silty mixtures. SC Clayey sands, poorly graded sand and clay mixtures. GRAVELS WITH FINES (Appreciable amount) SANDS, CLEAN SANDS (More than half of coarse fraction is smaller than a No. 4 sieve) SANDS WITH FINES (Appreciable amount) Fine-grained (More than half of material is smaller than a No. 200 sieve) SILTS AND CLAYS Liquid Limit Less than 50 Liquid Limit Greater than 50 HIGHLY ORGANIC SOILS ML Inorganic silts and very fine sands, rock flour, sandy silt and clayey-silt sand mixtures with a slight plasticity CL Inorganic clays of low to medium plasticity, gravelly clays, silty clays, clean clays. OL Organic silts and organic silty clays of low plasticity. MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts. CH Inorganic clays of high plasticity, fat clays. OH Organic clays of medium to high plasticity. PT Peat and other highly organic soils (rev. 6/05) PLOT PLAN REFERENCE: THIS PLOT PLAN WAS PREPARED FROM AN I NOTE: This Plot Plan is not to be used for legal purposes. Locations and dimensions are °pproxi— mate. Actual property dimensions and locations of utilities may be obtained from the Approved Building Plans or the "As—Built" Grading Plans. Haig/Scoff Property 3320 Highland Drive Carlsbad, CA. Figure No. II Job No. 06-9232 Geotechnical Exploration. Inc. July 2006 DENSE TREES DENSE TREES T_( Proposed Newoveway /__7 / HP-2 S SCALE: V'= = 20' TIIIuu1H HP-4 H _Th T PARCEL B DENSE TREES - HP-5 I DENSE TREES L__A Legend I ASSUMED PROPERTY BOUNDARY EXISTING TOPOGRAPHY (feet) EXISTING STRUCTURE PROPOSED CUT SLOPE APPROXIMATE LOCATION OF H EXPLORATORY HANDPIT PROPOSED FILL SLOPE 06-9232-p HP-5 i