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SDP 05-17; DONALD CONDOMINIUMS; LIMITED GEOTECHNICAL INVESTIGATION; 2004-02-04
I I· I I I I I I I .I I I I .1 ., ,I I ,1 :, C Soil and Foundation Engineers REPORT OF LIMITED GEOTECHNICAL INVESTIGATION Proposed Residential Project 2497 Ocean Street Carlsbad, California Job No. 04-4412 PREPARED FOR: Mr. Peter Donald c/o Wayne Davis Architect 343 4th Avenue, Suite 204 San Diego, CA 92101 PREPARED BY: C.W. La Monte Company Inc. 4350 Palm Avenue #25 La Mesa, CA 91941 4350 Palm Avenue #25 ♦ La Mesa, CA 91941 ♦ 619-462-9861 ♦ Fax 619 462-9859 :I ,, I' I ,, 1· I I I I I I) ·I I I ·I I I ., Soil and Foundation Engineers 4350 PALM AVENUE, SUITE 25 Phone: (619) 462-9861 • LA MESA, CALIFORNIA 91941 February 4, 2004 TO: Mr. Peter Donald c/o Wayne Davis Architect 343 4th Avenue, Suite 204 San Diego, CA 9210 I • Fax: (619) 462-9859 SUBJECT: Report of Limited Geotechnical Investigation Proposed Residential Project 2497 Ocean Street Carlsbad, California Job No. 04-4412 In accordance with your request, we have performed a soil investigation for the proposed residential project. We are presenting herein our findings and recommendations. In general, we found the site suitable for the proposed project provided that the recommendations contained herein are adhered to. The site is overlain with about 3 feet to 4 of loose topsoils, which are unsuitable for the placement of structures and improvements in their present condition. Where not removed by site grading, these materials require removal and replacement as properly compacted fill. The site is underlain at depth with competent marine terrace deposits. Recommendations to mitigate this and other site development considerations are discussed in the ensuing report. If you should 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, C.W. La Monte Company Inc. I' I I I I I ,, ,, IJ I ;I, I II TABLE OF CONTENTS PROJECT DESCRIPTION ............................................................................................................................ 1 SCOPE OF WORK ........................................................................................................................................ 1 FINDINGS ..................................................................................................................................................... 2 Site Description .......................................................................................................................................... 2 Description of Soils .................................................................................................................................... 3 Ground Water ............................................................................................................................................. 3 Existing Seawall ......................................................................................................................................... 3 TECTONIC SETTING ................................................................................................................................... 4 SEISMIC DESIGN PARAMETERS .............................................................................................................. 4 Uniform Building Code Design Information .............................................................................................. 4 Maximum Bedrock Acceleration ................................................................................................................ 5 GEOLOGIC HAZARDS ................................................................................................................................ 5 CONCLUSIONS .................................................................................................... , ....................................... 6 RECOMMENDATIONS ................................................................................................................................ 6 Earth Work and Grading .............................................................................................................................. 6 General ................................................................................................................................................... 6 Fill Suitability ......................................................................................................................................... 7 Observation of Grading .......................................................................................................................... 7 Clearing And Grubbing .......................................................................................................................... 7 Site Preparation ....................................................................................................................................... 7 Processing of Fill Areas .......................................................................................................................... 7 Compaction and Method of Filling ......................................................................................................... 7 Fill Slope Construction ........................................................................................................................... 8 Surface Drainage .................................................................................................................................... 8 Erosion Control. ...................................................................................................................................... 8 Temporary Slope Stability and Shoring ...................................................................................................... 9 Temporary Shoring ................................................................................................................................. 9 Shoring Design And Lateral Pressures ................................................................................................. I 0 Design Of Soldier Piles ........................................................................................................................ 10 Monitoring ............................................................................................................................................ 11 FOUNDATIONS ...................................................................................................................................... 11 General ................................................................................................................................................. 11 Di1nensions and Embedment ................................................................................................................ 11 Soil Bearing Value ................................................................................................................................ 11 Lateral Load Resistance ........................................................................................................................ 11 Foundation Reinforcement ................................................................................................................... 11 Anticipated Settlements ...... : ................................................................................................................. 12 Foundations Setback fro1n Slopes ......................................................................................................... 12 Foundation Excavation Observation ..................................................................................................... 12 Concrete Slabs-on-grade ........................................................................................................................... 12 Interior Floor Slabs ............................................................................................................................... 12 Moisture Protection .............................................................................................................................. 12 Interior Slab Cu.ring Tilne ..................................................................................................................... 13 Exterior Concrete Flatwork .................................................................................................................. 13 Design Parameters for Earth Retaining Structures ................................................................................... 13 Passive Pressure ............................................................................ : ....................................................... 13 Active Pressure for Retaining Walls ..................................................................................................... 13 Retaining Wall Foundations ..................................................................... : ........................................... 13 Waterproofing and Subdrain Observation ............................................................................................ 13 Backfill ................................................................................................................................................. 14 Foundation and Grading Plans Review ................................................................................................. 14 FIELD INVESTIGATION ............................................................................... , ........................................... 14 LABORATORY TESTS AND SOIL INFORMATION .............................................................................. 14 CONSTRUCTION NOTES ......................................................................................................................... 16 LIMITATIONS ............................................................................................................................................ 16 ' I, 1· ,, t ·I, I .f I ,, ' 1: I I I I I I I FIGURES Figure No. I Figure No. 2 Figure No. 3 Figure No. 4 Figure No. 5 APPEND IC/ES Site Location Map Plot Plan Test Excavation Logs Geologic Cross Section Retaining Wall Detail Appendix "A"-Standard Grading Specifications Appendix "B" -Unified Soil Classification Chart ' I I I t I I I ,& • I I ., 1. - I ,,· t I REPORT OF LIMITED GEOTECHNICAL INVESTIGATION Proposed Residential Project 2497 Ocean Street Carlsbad, California PROJECT DESCRIPTION The following report presents the results of a soil investigation performed for the proposed residential project. The project site is located at 2497 Ocean Street in the City of Carlsbad, California. Figure Number 1 ( attached) provides a vicinity map showing the location of the property. In general, the purpose of our investigation was to provide the foundation recommendations for the proposed condominium construction . .. The subject site supports and existing single family home, which will be razed to make way for two new residential units. An existing seawall along the west end of the site will remain. Plans for the proposed development had not been finalized at the time of our investigation. However, it is our understanding the new structure will be a maximum of two-stories in height over a subsurface parking. The structure will be of wood-frame construction and founded on conventional, shallow foundations with concrete slab-on-grade floors. Masonry retaining walls will be used in the garage construction. To aid in the preparation of this report, we were provided with a Topographic Survey prepared by Lintvedt, McColl & Asssociates. A copy of this plan was used as the basis for our Plot Plan and mapping and is included herewith as Figure No. 2. This report has been prepared for the exclusive use of the stated client and their design consultants for specific application to the project described herein. Should the project be changed in any way, the modified plans should be submitted to C.W. La Monte Company, Inc. for review to determine their 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, expressed or implied. SCOPE OF WORK The scope of this investigation was limited to: surface reconnaissance, research of readily available geological literature pertinent to the site; subsurface exploration, laboratory testing, geotechnical analysis of the field and laboratory data and preparation of this report. More specifically, the intent of this investigation was to: • Identify the subsurface conditions of the site to the depths influenced by the proposed grading and construction. • Based on laboratory testing and our experience with similar sites is the area, identify the engineering properties of the various strata that may influence the proposed I f, "' I I I I I ·- I I t, I I I I I· I • I co~struction, including .the allowable soil bearing pressures, expansive characteristics and settlement potential. • Describe the general geology of the site including possible geologic factors that could have an effect on the site development, and provide seismic design parameters established in the latest edition of the Uniform Building Code (Tables 16-J, Q, R, S, T and U). • Address potential construction difficulties that may be encountered due to soil conditions, groundwater, and provide recommendations concerning these problems. • Expose the existing seawall. • Develop soil engineering criteria for site grading. • Recommend an appropriate foundation system for the type of structure anticipated and develop soil engineering design criteria for the recommended foundation designs. • Provide design criteria for the design of earth retaining walls. • Present our opinions in this written report, that includes in addition to our findings and recommendations, a site plan showing the location of our subsurface explorations, logs of the test trenches and a summary of our laboratory test results. We did not evaluate the site for hazardous materials contamination. Further, we did not 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 below grade improvements. FINDINGS Site Description The project site consists of an rectangular shaped parcel of land located on the west side of Ocean Street in the City of Carlsbad, California. The lot has approximately 75 feet of street frontage and is about 135 feet deep. The property is further bounded on the north and south with developed residential property and on the west with the Pacific Ocean. Vegetation on the on the site consists of "ice plant", landscape shrubbery, and a few trees. Refer to the attached Site Location Map (Figure 1) and the Plot Plan (Figure 2) for the location and a layout of the site. The site is improved with an older, one and two-story single family residence with an attached garage situated on the rim of a moderately sloping sea bluff. Level terraces are constructed on the bluff face using masonry and natural stone retaining walls. An additional short stone wall is located across the western end of the propeliy. A fiel<l ~tone seawall is located along the western property boundary. However, the seawall is entirely buried under beach sand. Actual Job No. 04-4412 February 4, 2004 Page 2 I 1, I t I ' I I I I I ·1: I I 11 ' I I I on-site elevations range from about 11 feet (MSL) near the top of the seawall at the western property boundary to about 40 feet along Ocean Street. Description of Soils The subject site is located in the Coastal Plains Physiographic Province of San Diego County and is underlain by Quaternary-aged marine terrace deposits with associated topsoil and minor amounts of artificial fill. These soil types are described individually below; also refer the attached Test Excavation Logs, Figure No. 3. Artificial Fill: Minor amounts of fill soil exist on the site, primarily as retaining wall backfill and as a scattered veneer over the western end of the property. The fills are composed primarily of the topsoil described below with minor amounts of imported rock mixed in. The fill materials are not differentiated from the topsoil on the attached Test Excavation Logs. Topsoil: The site is typically overlain with about 3 to 4 feet of natural ground topsoil materials. These materials consist of dark reddish brown to dark brown, loose to medium dense, silty sand. Terrace Deposits: The site is underlain at depth with competent, Quaternary-aged terrace deposits. The encountered formational materials consists of light brown to tan, medium dense to dense, massively bedded, silty sand and sand (SP and SM). The terrace materials are poorly indurated and sometimes relatively cohesionless. Ground Water Groundwater was encountered in Test Excavation 5 at an elevation of approximately 6 feet above sea level. However, these groundwater conditions should not significantly impact the proposed development. The groundwater level will fluctuate somewhat with the sea level. It also should be kept in mind, that any required grading operations may 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 damage from such water is expected to be minor and cosmetic in nature, if good positive drainage is implemented at the completion of construction. Corrective action should be taken on a site-specific basis if, and when, it. becomes necessary. Existing Seawall Two manually excavated test explorations were placed adjacent to the existing seawall at the northwest comer of the property. The wall was entirely buried with "recent" beach sand and gravel deposits. The excavation extended to an approximate depth of 6 feet below the existing ground surface and was terminated due to groundwater and caving. The bottom of the wall was therefore not encountered. The exposed portion of the wall was constructed of irregular Job No. 04-4412 February 4, 2004 Page 3 I I I I I ' I I 1, ·1 I I I I· .I I I ,I I shaped field stones ranging up to boulder size. The field stones were typically integrated with a cement-based mortar. A stairway descends from the north end of the wall. 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 are characterized by a series of active fault zones that generally strike in a northerly to north-westerly direction. 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 (within the last 11,000 years). A review of available geologic maps indicates that the active Rose Canyon Fault Zone is located within 7 kilometers of the subject site. The maximum probable earthquake on the Rose Canyon Fault Zone is considered to be at 6.9 Richter Magnitude as determined from the 1997 addition of the Uniform Building Code. 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, Earthquake Valley, San Jacinto, and San Andreas Fault Zones to the northeast. However, because of its close proximity to the site, the Rose Canyon Fault Zone is considered the most significant nearby fault with respect to the potential for seismically induced ground shaking. Therefore, we recommend the structure be designed for a 6.9 earthquake on the Rose Canyon Fault Zone. SEISMIC DESIGN PARAMETERS Uniform Building Code Design Information Seismically related design parameters obtained from the Uniform Building Code (UBC) 1997 edition, Volume II, Chapter 16, are presented below in Table. These design factors are based on subsurface soil and bedrock conditions and distance of the site from known active faults. SEISMIC DESIGN PARAMETERS UBC Chapter 16 Seismic Recommended Table No. Parameter Value 16-I Seismic Zone Factor Z 0.40 16-J Soil Profile Type Sd 16-Q Seismic Coefficient Ca 0.44 Na 16-R Seismic Coefficient Cv 0.64 Nv 16-S Near Source Factor Na 1.0 16-T Near Source Factor Nv 1.2 16-U Seismic Source Type B Job No. 04-4412 February 4, 2004 Page 4 I ·I f. I ,, I I I I. ' I I l I I • I I I Maximum Bedrock Acceleration Based upon a Maximum Magnitude Earthquake of 6.9 magnitude along the nearest portion of the Rose Canyon Fault Zone, the Maximum Bedrock Acceleration at the site is estimated to be 0.45 g. For structural design purposes, we recommend a damping ratio not greater than 5 percent of critical dampening. 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 a result of movement along one of the major active fault zones mentioned above. Probable ground shaking levels at the site could range from slight to severe, 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 structure. Construction in accordance with the minimum requirements of the Uniform Building Code, the Structural Engineers Association of California lateral force design requirements, and local governing agencies should minimize potential damage due to seismic activity. Landslide Potential and Slope Stability: As part of this investigation we reviewed the publication, "Landslide Hazards in the Northern Part of the San Diego Metropolitan Area" by Tan and Giffen, 1995. This reference is a comprehensive study that classifies San Diego . County into areas of relative landslide susceptibility. The subject site is located in an area classified as 3-1. The 3-1 classification is assigned to areas generally susceptible to slope movement. Slopes within the 3-1 classification are considered at or near their stability limits due to steep slopes and can be expected to fail locally when adversely modified. Sites Within this classification are located outside the boundaries of known landslides but generally contain observably unstable slopes that may be underlain by weak materials and/or adverse geologic structure. Due to the sites gently sloping topography and underlying, competent, massively bedded terrace deposits, landslide and deep-seated slope failure hazards are considered nominal. Liquefaction: The terrace materials at the site are not subject to liquefaction due to such factors as soil density, grain-size distribution, and groundwater conditions. Flooding: The site is located outside the boundaries of both the 100-year and the 500-year flood plains according to the maps prepared by the Federal Emergency Management Agency. Tsunamis: Tsunamis are great sea waves produced by submarine earthquakes or volcanic eruptions. Based upon the location and elevation of the site in relation to the ocean, tsunami risk is considered low. Job No. 04-4412 February 4, 2004 Page 5 I I I I •/ I I I. ,. I I: t ·1 I ,. I I I Seiches: Seiches are periodic oscillations in large bodies of water such as lakes, harbors, bays or reservoirs. Due to the site's location, it is not considered subject to seiche activity. CONCLUSIONS In general, we found the subject property suitable for the proposed construction, provided the recommendations provided herein are followed. A significant geotechnical condition that will affect the construction of the improvements as proposed may be the need for temporary shoring during the construction of the parking garage retaining walls. Based on the proximity of the proposed walls to the property lines, it will not be feasible to maintain the required minimum temporary slope inclination in these areas. Further, the temporary excavations can result in undermining and damage to adjacent buildings and improvements. Therefore, it will be necessary to provide shoring in areas where this minimum temporary slope inclination cannot be maintained. Most likely shoring will be required along the northern and southern property lines and possibly along portions of the easterly property line. Specific recommendations for temporary excavation and shoring are presented in the following sections of this report. The shoring system shall be designed by a qualified professional engineer, based on the parameters provided in this report. In addition, a relatively thin veneer of loose to medium dense fill and topsoil material caps the site. These surficial soils are considered unsuitable for the support of settlement-sensitive structures in their present loose condition. However, based on the anticipated finish floor elevations and the existing site conditions, it appears that the cut depths required for the parking garage will remove much of the loose soil from the construction area, exposing competent terrace materials at finish floor grades. Any areas remaining with loose fill and topsoil should be removed and replaced as properly compacted fill. Our specific recommendations for site development are detailed under separate headings in following sections of this repo1i. :;11 t! t~ t{ ~~ tr, RECOMMENDATIONS Earth Work and Grading General All grading should confonn with the guidelines presented in Appendix Chapter A33 of the Uniform Building Code, the minimum requirements of the City of Carlsbad, and the Recommended Grading Specifications and Special Provisions attached hereto, except where specifically superseded in the text of this report. Prior to grading, a representative of C. W. La Job No. 04-4412 February 4, 2004 Page 6 I I I I I ,, I I I, II I I I I ,I I 1 .I I Monte Company Inc. Inc. should be present at the preconstruction meeting to provide additional grading guidelines, if necessary, and to review the earthwork schedule. Fill Suitability On-site excavated materials may be used as compacted fill material or backfill. The on-site materials, typically, posses a very low to low expansion potential. Any potential import soil sites should be evaluated and approved by the Geotechnical Consultant prior to importation. 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 most desirable for import is a non-detrimentally expansive granular material with some silt or clay binder. Observation of Grading Observation and testing by the soil engineer is essential during the grading operations. This observation can range from continuous to an as-needed basis, based on the project situation. This allows the soil engineer to confirm the conditions anticipated by our investigation, to allow adjustments in design criteria to reflect the actual field conditions exposed, and to determine that the grading proceeds in general accordance with the recommendations contained herein. Clearing And Grubbing Site preparation should begin with the removal of the all structures, vegetation and other deleterious materials from the portion of lot that will be graded and that will receive improvements. This should include all root balls from the trees to be removed and all significant root material. The resulting materials should be disposed of off-site. Site Preparation Proposed grading will consist primarily of an excavation and export operation to construct the subsurface parking garage. It is anticipated the removal operations will expose competent terrace deposits at the finish garage floor elevations. However, we recommend removal any remaining loose topsoil material in areas that will support settlement-sensitive improvements or receive additional fill. As the project is presently planned, soil removals are expected to vary from about 3 to 4 feet, but may be thicker in localized areas. Removals should extend laterally a minimum distance equal to the depth of removal. The loose soil shall be removed to expose firm natural ground as determined by our field representative during grading. All removal areas should be approved by a representative of our office prior to the placement of fill or improvements. Processing of Fill Areas Prior to placing any 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 approximately 6 to 12 inches, moisture conditioned, and compacted to at least 90 percent relative compaction. 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 its maximum dry density as determined by ASTM Laboratory Test Dl557-91. Fills Job No. 04-4412 February 4, 2004 Page 7 I I I I I ' I, I I I ,, I· I I I I I 1. I 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. All material should be free of rocks or lumps of soil in excess of twelve inches in maximum width. However, in the upper two feet of pad grade, no rocks or lumps of soil in excess of six inches should be allowed. Utility trench backfill within five feet of the proposed structure and beneath all pavements and concrete flatwork should be compacted to a minimum of 90 percent of its maximum dry density. The upper one-foot of pavement subgrade and base material should be compacted to at least 95 percent relative density. All grading and fill placement should be performed in accordance with the local Grading Ordinance, the Uniform Building Code, and the Recommended Grading Specifications and Special Provisions attached hereto as Appendix A. Fill Slope Construction Fill slopes that may be constructed, should be constructed at an inclination of 2: 1 or flatter (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 may be overfilled by at least three feet and then cut back to the compacted core at the design line and grade. • Surface Drainage Surface runoff into 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 the proposed buildings should be graded so that surface water flows rapidly away from the buildings without ponding. In general, we recommend that the ground adjacent to buildings slope away at a gradient of at least two-percent. Densely vegetated areas where runoff can be impaired should have a minimum gradient of five percent within the first five feet from the structure. Planter boxes adjacent to structures should be constructed with a subsurface drain, jnstalled in gravel, which empties into an adequate drainage facility. Erosion Control In addition, appropriate erosion-control measures shall be taken at all times during construction to prevent surface runoff waters from entering footing excavations, ponding on finished building pad or pavement areas, or running uncontrolled over the tops of newly constructed cut or fill slopes. Appropriate erosion control devices should be provided in accordance with local and federal governing agencies. Job No. 04-4412 February 4, 2004 Page 8 ., I I I ,I ' t • , I I I I I I ., ,I ii :1 :1 Temporary Slope Stability and Shoring Temporary cut slopes of less than 15 feet in height are anticipated along the perimeters of the prop·erty. Based upon the results of our subsurface explorations, it is anticipated that relatively competent formational terrace material will be encountered within the majority of the temporary cut slopes. However, the terrace materials posses low cohesion characteristics and will not stand well in steep cuts. As such, unshared temporary cut slopes in competent formational materials require excavations at inclinations of 1 to 1 (horizontal: vertical) or flatter. Existing off-site structures are located within 5 feet of the north, and south property lines. Therefore, temporary cut slopes sloped at the recommended inclinations are not feasible in these areas. Excavation shoring should be provided in such location where undermining or other damage to adjacent structures and improvements is an issue. Recommendations for shoring are provided in the following sections of this report. The location of underground utilities should be determined before placing excavations along the Street right-of-way. Unshared temporary cuts should not be placed in areas that effect the lateral stability of underground utilities . Temporary cut slopes should be observed by the Geotechnical Consultant during grading to ascertain that no unforeseen adverse conditions exist. No surcharge loads such as stockpiles, vehicles, etc. should be allowed within a distance from the top of temporary slopes equal to half the slope height. The contractor is solely responsible for designing and constructing stable, temporary excavations and will need to shore the sides of trench excavations as required to maintain the stability of the excavation sides. 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. Temporary cut slopes should be constructed in accordance with the recommendations presented in this section. In no other case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety regulations. Temporary Shoring Because sufficient space for sloped embankments will not be available in some areas, shoring of construction slopes will be necessary. One common method of shoring consists of steel soldier piles ("!"-beams) placed in drilled holes that are backfilled with concrete. Treated wood lagging is spanned between the piles to retain the excavation. Any other, unconventional methods of shoring should be reviewed and approved by our firm prior to implementation. Soldier pile systems typically use tieback anchors or internal bracing to provide additional lateral support. However, the use of tiebacks anchors would require encroachment permits from all surrounding property owners. Since the temporary cuts are relatively short (less than 15 feet), the system probably can be constructed economically without the tiebacks. If additional lateral support is required the soldier piles of the shoring system may be internally Job No. 04-4412 February 4, 2004 Page 9 I 1· I I .I I I I I I I I I I I I I 1. I braced. The following information on the design parameters and installation of a shoring system is conceptual at this time. We recommend that a specialty contractor with experience in shoring, bracing, and tiebacks provide the shoring recommendations and plans. We can furnish additional recommendations as the design progresses. Shoring, bracing, and tiebacks may be designed using the following soil parameters: Angle of internal friction: Apparent cohesion: Total Unit weight: 31 degrees 60 psf 125 pcf Shoring Design And Lateral Pressures For design of cantilevered shoring, a triangular distribution of lateral earth pressure may be used. It may be assumed that retained soils having a level surface behind the cantilevered shoring will exert a lateral pressure equal to that developed by a fluid with a density of 30 pounds per cubic foot. In addition to the recommended lateral earth pressure, the upper 10 feet of shoring adjacent to streets should be designed to resist surcharge loads behind the shoring due to normal street traffic and parked automobiles. If the traffic surcharge is kept back at least 1 0 feet from the shoring, the traffic surcharge may be neglected. Design Of Soldier Piles Soldier piles should be spaced horizontally at least two diameters on centers. The allowable lateral bearing value (passive value) of the soils supporting the soldier piles below the level of excavation may be assumed to be 600 pounds per square foot per foot of depth extending from the excavated surface, increasing up to a maximum of 6,000 pounds per square foot. To develop the full lateral value, provisions should be taken to assure firm contact between the soldier piles and the undisturbed formational soils. The concrete placed in the soldier pile excavations may be a lean mix concrete. However, the concrete used in that portion of the soldier pile which is below the planned excavation level should be of sufficient strength to adequately transfer the imposed loads to the surrounding soils. The frictional resistance between the soldier piles and the retained earth may be used to aid in resisting the downward component of the loading. The coefficient of friction between the concrete of the soldier piles and the retained earth may be taken as 0.5. This frictional value is based on the assumption that uniform full bearing will be developed between the steel soldier beam and the lean-mix concrete and between the lean-mix concrete and the retained earth materials. In addition, the full bearing resistance of the soldier piles below the excavated level may also be used to resist downward loads. The frictional resistance between the concrete soldier piles and the soils below the excavated level may be taken as equal to 500 pounds per square foot. Job No. 04-4412 February 4, 2004 Page 10 I I I I I I I. I I I I I I ·1 I I Monitoring Some means of monitoring the perfonnance of the shoring system is recommended. The monitoring should consist of periodic surveying of the lateral and vertical locations of the tops of all the soldier piles. FOUNDATIONS General Based on the. findings of our investigation, it is our opinion the proposed strictures may be supported by conventional continuous and isolated spread footings. The on-site soils possess a low expansive potential, and therefore, it is anticipated that no special consideration and design for heaving soils will be required. Dimensions and Embedment Conventional shallow foundations may be utilized in the support of the proposed structures. Foundations should be constructed in accordance with the recommendations of the project structural engineer. The following recommended foundation dimensions are provided in the Uniform Building Code: Number of Floors Supported by Width of Footing Embedment Depth Below The Foundation (Inches) Undisturbed Soil 1 12 12 2 15 18 3 18 24 Soil Bearing Value A bearing capacity of 2000 psf may be assumed for said footings when founded a minimum of 12 inches into firm natural ground or properly compacted fill. This bearing capacity may be increased by one-third, when considering wind and/or seismic loading. 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 0.45. 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 against undisturbed, natural ground soil. If a combination of the passive pressure and friction is used, the friction value should be reduced by one-third. Foundation Reinforcement It is recommended that continuous footings be reinforced with at least four No.5 steel bars; two reinforcing bars shall be located near the top of the foundation, and two bars near the Job No. 04-4412 February 4, 2004 Page 11 I I I ,. I I I I I I I I I I I. I ·1 .I :, bottom. The steel reinforcement will help prevent damage due to post construction settlement and heaving, resulting from variations in the subsurface soil conditions. This recommendation does not supersede reinforcement required for structural considerations. Anticipated Settlements Based on our experience with the soil types on the subject site, the soils should experience settlement in the magnitude ofless than 0.5 inches. It should be recognized that minor hairline cracks normally occur in concrete slabs and foundations due to shrinkage during curing and/or redistribution of stresses and some cracks may be anticipated. Such cracks are not necessarily an indication of excessive vertical movements. Foundations Setback from Slopes Soils comprising the slope face are subject to down slope creep and/or lateral "relaxation", even if properly placed and compacted. For this reason foundations and footings located near the top or within the face of a slope, require a deepened foundation. The depth required should be detennined by the geotechnical engineer at the time of construction. The embedment will vary deepening on the localized thickness of fill and topsoil material. Foundation Excavation Observation All foundation excavations should be observed by the Geotechnical Consultant prior to placing reinforcing steel and formwork in order to verify compliance with the foundation recommendations presented herein. All footing excavations should be excavated neat, level and square. All loose or unsuitable material should be removed prior to the placement of concrete. Concrete Slabs-on-grade Interior Floor Slabs The minimum floor slab thickness the floor slab should be four inches. The floor slabs should be reinforced with at least No. 3 bars placed at 18 inches on center each way. Slab reinforcing should be supported by chairs and be positioned at mid-height in the floor slab. Moisture Protection Where the concrete on-grade floor slabs will support moisture-sensitive floor coverings, it should be underlain by a moisture barrier. The slab shall be underlain with two inches of clean sand overlying a 6 mil Visqueen moisture barrier, overlying an additional two inches of clean sand or native on-site sands. Joints in the Visqueen sheeting should overlapped at least 12 inches. Job No. 04-4412 February 4, 2004 Page 12 I I I I I I ·I I I I I I I I Interior Slab Curing Time Following placement of concrete floor slabs, sufficient drying time must be allowed prior to placement of floor coverings. Premature placement of floor coverings may result in degradation of adhesive materials and loosening of the finish floor materials. Prior to installation, standardized testing can be performed to determine if the slab moisture emissions are within the limits recommended by the manufacturer of the specified floor-covering product. 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 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 Concrete Institute specifications. When patio, walks and porch slabs abut perimeter foundations they should be doweled into the footings. Design Parameters for Earth Retaining Structures Passive Pressure The passive pressure for the prevailing soil conditions may be considered to be 350 pounds per square foot per foot of depth. This pressure may be increased one-third for seismic loading. The coefficient of friction for concrete to soil may be assumed to be 0.45 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. Active Pressure for Retaining Walls The active soil pressure for the design of "unrestrained" and "restrained" earth retaining structures with level backfill may be assumed to be equivalent to the pressure of a fluid weighing 30and 45 pounds per cubic foot, respectively. These pressures do not consider any other surcharge and assume a drained backfill condition. Retaining Wall Foundations Retaining walls associated with the structure should be supported by foundations with the minimum dimensions as recommended in the "Foundations" section of this report. Waterproofing and Subdrain Observation The project architect shall provide specifications for retaining wall drainage and water proofing. Retaining walls that are not· properly waterproofed and drained are potentially subject to cosmetic staining (such as efflorescence), surficial spalling and decomposition and/or excessive moisture emissions (and resulting problems) into interior space areas. Job No. 04-4412 February 4, 2004 Page 13 I ,. I _,, I I I I I I I I I I I I I Backfill All backfill soils should be compacted to at least 90% 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. Foundation and Grading Plans Review The finalized, foundation and grading plans should be submitted to this office for review to ascertain that the recommendations provided in this report have been followed and that the assumptions utilized in its preparation are still valid. Additional or amended recommendations may be issued based on this review. FIELD INVESTIGATION Four hand auger borings and two manually excavated test explorations were placed on the site, specifically in areas where representative soil • conditions were expected and where the proposed structures will be located. The two excavations were placed adjacent to the seawall. Our investigation also included a visual site reconnaissance. The excavations were visually inspected and logged by our field geologist, and samples were taken of the predominant soils throughout the field operation. Test excavation logs have been prepared on the basis of our inspection and the results have been summarized on Figures No. 3. The predominant soils have been classified in conformance with the Unified Soil Classification System (refer to Appendix B). LABORATORY TESTS AND SOIL INFORMATION Laboratory tests and evaluations were performed on the disturbed and undisturbed soil samples in order to determine their physical and mechanical properties and their ability to support the proposed structure. The following evaluations were conducted on the sampled soils: Classification Field classifications were determined by visual examination. The final soil classifications are in accordance with the Unified Soil Classification System and are presented on the attached field logs, Figure No. 3. 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 test excavation logs. Job No. 04-4412 February 4, 2004 Page 14 I I I I I I I I I I I I I I I I I I I Maximum Dry Density Maximum dry density determinations were performed on representative samples of the soils used in the compacted fills according to A.S.T.M. Test 1557-91, Method A guideline. The results of these tests, as presented below. B-3 3' to 5' Red-brown, silty sand 124 cf 0 timum Moisture Content: 9.0% Direct Shear Data Sample Number: Angle of Friction Apparent Cohesion B-3 @6' to 8' 31 Degrees 60PSF GRAIN SIZE DISTRUBUTION: The grain size distribution of selected samples was determined in accordance with ASTM D422. The results of these tests are presented below. Sample Location Sieve Size #4 #8 #20 #30 #60 #100 #200 Soil Type: SP B-1@ 9' to 12' Percent Passing 100 98 80 68 18 10 5 EXP ANSI ON INDEX: The expansion potential of the subgrade soil was visually classified according to the UBC Expansion Index Test method and texturally determined to be non expans1ve. Job No. 04-4412 February 4, 2004 Page 15 I I I I I I I I I I I I I I I ,,I ,I ,I CONSTRUCTION NOTES 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. 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 personnel other than our own on the site; the safety of other is the responsibility of the Contractor. The Contractor should notify the Owner if he considers any of the recommended actions presented herein to be unsafe. LIMITATIONS Our conclusions and recommendations have been based on all available data obtained from our field investigation and laboratory analysis, as well as our experience with the soils and formational materials located in the area. Of necessity, we must assume a certain degree of continuity between exploratory excavations and/or natural exposures. It is, therefore, necessary that all observations, conclusions, and recommendations be verified at the time grading operations begin or when footing excavations are placed. In the event discrepancies are noted additional recommendations may be issued, if required. The work performed and recommendations presented herein are the result of an investigation and analysis, which meets the contemporary standard of care in our profession. No other warranty is expressed or implied. This report should be considered valid for a period of three (3) years, and is subject to review by our firm following that time. If significant modifications are made to the building and/or grading plans, especially with respect to the height and location of any cut and fill slopes, and the height and location of any proposed structures, this report must be presented to us for immediate review and possible revision. The firm of C.W. La Monte Co. Inc. shall not be held responsible for changes to the physical condition of the property, such as addition of fill soils or changing drainage patters, which occur subsequent to the issuance of this report. Job No. 04-4412 February 4, 2004 Page 16 I I I I I I I I I, I I I I I I I I I •~~ ...... SITE LOCATION MAP Proposed Residential Project 2497 Ocean Street Carlsbad, CA ':' :·. p,~~~~ ,·: .. ':; : . :::ci;crtt·j;_J.,/}.;.~?":.~:/i)~'··,;::•,:;,,,.'::,:::,ltle~~~~;;;J.~J@O,::::·::.:,:·:::::-~o~.~.q/i;;.:·::>:":::~~Qq}~t:'.r •, ,::::::'. • • i:•._:; ·:.:'.,,>::> .:d:i.i<>:<!:Priht~4.fto¼.t\.:TOf•()l.:©.l~9.lWMtb31?ji.-fitid-&.:lidii1Hm~uJ . : ... '. .. •:.:. . ........... . C.W. La Monte Company Inc. Soil and Foundation Engineers Job No. 04-4412 Figure No. 1 .... _ .. ________ .......... .. .. .. 1111 LEGEND Approximate Scale: 1" = 25' PACIFIC OCEAN Approximate Test Excavation Location -e Approximate Test Boring Location 8-1 . Existing Topographic Contours -----------25 Existing Structure Existing Structure (To be removed) ['------'s-4 el I -, ,. . ,. 'OB CURED I \ \ \ \ JOB NO. 04-4412 JI II II I II I I-4i w w 0:: I-{/) z <( w u 0 FIGURE NO. 2 'I I I I I I I I I I I I I I I I --r:'1 i;;., Log of Test Boring No. 1 r.J ,__ u ~ E--'I, Q., ~ Q., 0 ._, ._, C' ~ 0 > -~ < ; ~~ Surface Elevation:± 23' Date: Logged By: JBR ~ i;;., E--1/23/04 -00 ,.... uu --~ s~ = r:'1 E--Drilling Method: 4" Dia. Hand Auger Drive Weight: 35# Drop: 30" r"'I z ~ r:'1 r..;i ci5 ~ ,.... ~ ~ r..;i 0 A 00 Sampling Methods: 2.5" I.D. Sampler -,i: ~ ~ === ~ ~ ~ d A ;;;, ~ = = A A DESCRIPTION OF SUBSURFACE CONDITIONS SM TOPSOIL ;,,:~/. Dark red brown, slightly moist, loose to medium dense, silty sand. }~t: ~ ,-'t.( 1>,••;5.' ~-;.;: \'il. !:V;~ ji;~ SM TERRACE DEPOSITS 5 Red brown, very moist, medium dense, silty sand. ---------------- SP Light brown-tan, very moist, medium dense to dense, slightly silty sand SM and fine to medium sand. 15--l---ll---1-----+--~----1 ...... --1--------------------------------1 EXCAVATION BOTTOM 20 25-..l.-L-.-l---l----l----l----ll.--------------------------------1 PROJECT: JOB NO. 04-4412 Proposed Residential Project 2497 Ocean Street Carlsbad, California FIGURE NO. 3a I I I I I I I I I I I I I I I I, I I I r:r.i r.;i ---,..J ~ ~ ~ .. 0 ---~ 0 Cl.I < r.;i ~ ~ ~ -r:r.i ;;.;;i --= rr.i ~ f-i :z: g r:r.i -~ ~ r.;i 0 r..:i s > ,..J ~ Q ; = = Q 7.5 5 10 15 20 ---~ u ~ > ~ -rr.i :z: r.;i Q ~ Q 108 ~ Log of Test Boring No. 2 ~ 00 -< . uu Surface Elevation:± 28' Date: 1/23/04 Logged By: JBR ii r,j til ;;i Drilling Method: 4" Dia. Hand Auger Drive Weight: 35# Drop: 30" rr., Sampling Methods: 2.5" J.D. Sampler -< ~ u DESCRIPTION OF SUBSURFACE CONDITIONS SM TOPSOIL' Dark red brown, slightly moist, loose to medium dense, silty sand. SM TERRACE DEPOSITS Red brown to light brown, slightly moist to moist, medium dense, slightly silty sand with occasional small "pockets" of clayey sand. SP Light brown to tan, very moist, medium dense to dense, slightly silty sand and sand. SM EXCAVATION BOTTOM 25....JL......L-.J-----1-----1----4--J....-----------------------------; PROJECT: JOB NO. 04-4412 Proposed Residential Project 2497 Ocean Street Carlsbad, California FIGURE NO. 3b I I I I I I I I I I I I I I I I· I I I c:'1 li;l ---1-"l I""' 't?. =--0 ,_., 0 ~ 0 Cl; < ~ ~ r-. 00. ---;;;i ~ r.f.l I""' z g rJ1 .... 0,. ~ w 0 ~ ,..;i > 1-"l :; Q ;;;i ! = = 8.0 5 JO 15 20 5 ~ ;>< I""' .... 00 z li;l Q ~ Q 107.7 ~ ... I""' 00. < . uu i;; !"Ii 00 ;;:i ,;/) <: ..;i u SM SM SP SM Log of Test Boring No. 3 Surface Elevation:± 37' Date: 1/23/04 Logged By: JBR Drilling Method: 4" Dia, Hand Auger Drive Weight: 35# Drop: 30" Sampling Methods: 2.5" I.D. Sampler DESCRIPTION OF SUBSURFACE CONDITIONS TOPSOIL Dark red brown, slightly moist, loose to mediwn dense, silty sand. TERRACE DEPOSITS Red brown, very moist, medium dense, silty sand. ----------------- Light brown to tan, very moist, medium dense to dense, slightly silty sand and sand and fine to medium sand. EXCAVATION BOTTOM 25-JL-.L--l--~L----'----.J-----i.--------------------------------1 PROJECT: JOB NO. 04-4412 Proposed Residential Project 2497 Ocean Street Carlsbad, California FIGURE NO. 3c I I I I I I I I I I I I I I I I I I I rJ1 ~ Log of Test Boring No. 4 r.;i ....... u ~ E--~ ~ ~ Q., C, 0 .._. ~ ~ 0 .... 4) < ; >, ~~ Surface Elevation:± 37.5' Date: l/23/04 Logged By: JBR ~ r.c E--rJ1 .... uu --= rJ1 t ~ s c,,i Drilling Method: 4" Dia. Hand Auger Drive Weight: 35# Drop: 30" ~ :z: g .... r.;i 00 ;:;i 0., ~ r.;i 0 A ~ Sampling Methods: 2.5" I.D. Sampler ~ ~ s ~ ~ ~ ,..;i ~ :::i = u = A A DESCRIPTION OF SUBSURFACE CONDITIONS SM TOPSOIL Dark red brown, slightly moist, loose to medium dense, silty sand. 6.9 109 SM TERRACE DEPOSITS Red brown, very moist, medimn dense, silty sand. 5 SP Light brown to tan, very moist, medium dense to dense, slightly silty sand and sand and SM fine to medium sand. 10 EXCAVATION BOTTOM 15 20 25 ..................... _--l _____ ...._ __ +-_________________________________ -t PROJECT: JOB NO. 04-4412 Proposed Residential Project 2497 Ocean Street Carlsbad, California FIGURE NO. 3d I I I I I I I I I I I I I I I I I I I ISAMPLE TEST EXCAVATION NO. 1 -~ TY >E t:, Cia: )'!%j ~ 0 oo t:r.l 2 ,-. t,:j t:, = t:r.l ~ ""d z ,-. z ..., 00 d ~ t;;;j (j r:l.l~ ~,_;ir:l.l ~ ~ 0 t,:j ,.;i 0 ~s ,_, C: ;'-' Elevation:± 10.5' Date: 1/22/04 Excavation Method : Manual ::,:, z~ = .., t:r.l l':1 SOIL DESCRIPTION 1:1 BEACH SAND 1 -Light gray, moist, medium dense, fine to medium sand. 2 - 3 -@ 3 -3.5' Abundant gravel and cobble. 4 - 5 -@ 5 -6' Abundant gravel and cobble. 6 EXCAVATION BOTTOM 7 •Ground water level @5 feet. -• Excavation Terminated along side of field stone retaining wall. •Caving 5-6' do to ground water. SAMPLE TEST EXCAVATION NO. 2 -~ TYPE t:, na: ~ M 0 ,-, t:r.l t:, oo = ~ 1-'d 2 ....... z-00 d ~ t;;;j i:, ""dZ~ ~.., en ~ 0 iii (j 00 >< ..!,. t:r.l ,.;i = i:--l ~..., ~ Elevation: -:. 10.5' ;,::: 0 '-' .., z c:: Date: 1/22/04 Excavation Method : Manual :,:, >< .., ~ = l':1 t:r.l SOIL DESCRIPTION i:, BEACH SAND 1 -Light gray, moist, medium, fine to medium sand. 2 - 3 4 -EXCAVATION BOTTOM 5 - 6 - 7 - PROJECT: Proposed Residential Project C.W. LA MONTE COMPANY INC. 2497 Ocean Street Carlsbad, California Soil and Foundation Engineers PROJECT NO. 04-4412 FIGURE NO. 3e I • I ,. I I t I ~ I l 1---1=----~ 1 I ' I I , I I • I I .1 I ~, I :1 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 ~ ~~ ~i! Ja;l- d ',I I' TERRACE DEPOSITS 20 Existing Ground Surface ":1 ! ,.-r , DISTANCE (Feet) (Unsuitable Material) 40 Cross Section A -A' Scale I" = 10' (Horizontal and Vertical) Existing Ground Surface Undifferentiated Topsoil and Fill TERRACE DEPOSITS n C 60 80 100 Stone Walls Existing Ground /Surface -__,,__ TERRACE DEPOSITS 120 ? 140 BEACH SAND Residential Project PROJECT: 97 o Str t C.W. La Monte Company Inc ~~tsb:i,~A ee ~-----,-----'-----. Soil and Foundation Engineers Job No. 04-4412 Figure No. 4 ~I :I :1 :1 :1 '.I :1 :1 .I :I I .1 :1 .1 I ,I ·1 ) I. I ·1 ~ I I \ I -{ I --~· ...1.. .6"MIN' WATEP.PAOOF BACK OF WALL PSR ARCHITECT'S SPECIFICATtONS ~--+----3/4 !NCH GAUSHEP ROCK Ot MIRAORAIN 6QOO o~ EQUIVALENT ~~---t---GEOFA8RIC B!:iWEEN-AOC·K ANO 'SOIL 12" Min. Minimum 4 Inch Diameter Pipe Slope 1% Minimum to Suitable Outlet TOP OF GAOUN.D er CONCRETE SLAB RETAINING WALL SUBDRAIN DETAIL C.W. LAMONTE COMPANY Soil and Foundation Engineers (No Scale) Job No 04-4412 Fi~re No. 5 I I I I I I I I I I I I I I I I I I I Appendix A STANDARD GRADING SPECIFICATIONS These specifications present the usual and minimum requirements for projects on which C. W. La Monte Co. Inc. is the geotechnical consultant. No deviation from these specifications will be allowed, except where specifically superseded in the preliminary geology and soils report or in other written communication signed by the Soils/Geotechnical Engineer or Engineering Geologist ofrecord. • GENERAL A. The Soils/Geotechnical Engineer and Engineering Geologist are the ·o"vner's or Builders' representatives on the project. For the purpose of these specifications, participation by the Soils Engineer includes that observation performed by any person or persons employed by, and responsible to, the licensed Civil or Geotechnical Engineer signing the soils reports. B. The Contractor under the supervision of the Soils Engineer shall conduct all clearing, site preparation, or earthwork performed on the project. C. It is the Contractor's responsibility to prepare the ground surface to receive the fills to the satisfaction of the Soils Engineer and to place, spread, mix, water, and compact the fill in accordance with the specifications of the Soils Engineer. The Contractor shall also remove all material considered unsatisfactory by the Soils Engineer._ • D. It is also the Contractor's responsibility to have suitable and sufficient compaction equipment on the job site to handle the amount of fill being placed. If necessary, excavation equipment will be shut down to permit completion of compaction. The Contractor will also provide sufficient watering apparatus, with due consideration for the fill material, rate of placement, and time of year. E. A final report shall be issued by the Soils Engineer attesting to the Contractor's confonnance with these specifications. SITE PREPARATION A. All vegetation and deleterious material shall be disposed of off site. This removal shall be concluded prior to placing fill. B. Soil, alluvium, or bedrock materials determined by the Soils Engineer as being unsuitable for placement in compacted fills shall be removed from the site. The Soils Engineer must approve any material incorporated as a part of a compacted fill. C. After the ground surface to receive fill has been cleared, it shall be scarified, disked, or bladed by the Contractor until it is uniform and free from ruts, hollows, hummocks, or other uneven features which may prevent uniform compaction. The scarified ground surface shall then be brought to optimum moisture, mixed as required, and compacted as specified. If the scarified zone is greater than 12 inches in depth, the excess shall be removed and placed in lifts restricted to 6 inches. Prior to placing fill, the ground surface to receive fill shall be inspected, tested as necessary, and approved by the Soils Engineer. D. Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks, wells,. pipelines, or others are to be removed or treated in a manner prescribed by the Soils Engineer and /or governing agency. E. In order to provide uniform bearing conditions in cut-fill transition lots and where cut lots are partially in soil, colluvium, or unweathered bedrock materials, the bedrock portion of the lot extending a minimum of 3 feet outside building lines shall be over excavated a minimum of3 feet and replaced with compacted fill. 1 I I I I I I I I I I I I I I I I I I I Appendix A STANDARD GRADING SPECIFICATIONS COMPACTED FILL A. Any material excavated from the property may be utilized in the fill, provided each material has been determined to be suitable by the Soils Engineer. Roots, tree branches, and other deleterious matter missed during clearing shall be removed from the fill as directed by the Soils Engineer. B. Rock fragments less than 6 inches in diameter may be utilized in the fill, provided: 1. They are not placed in concentrated pockets. 2. There is a sufficient percentage of fine-grained material to surround the rocks. 3. The Soils Engineer shall supervise the distribution of rocks. C. Rocks greater than 6 inches in diameter shall be taken off site, or placed in accordance with the recommendations of the Soils Engineer in areas designated as suitable for rock disposal. D. Material that is spongy, subject to decay or otherwise considered unsuitable should not be used in the compacted fill. E. Representative samples of material to be utilized as compacted fill shall be analyzed by the laboratory of the Soils Engineer to detennine their physical properties. If any material other than that previously tested is encountered during grading, the Soils Engineer shall conduct the appropriate analysis of this material as soon as possible. F. Material used in the compaction process shall be evenly spread, watered processed, and compacted in thin lifts not to exceed 6 inches in thickness to obtain a uniformly dense layer. The fill shall be placed and compacted on a horizontal plane, unless otherwise approved by the Soils Engineer. G. If the moisture content or relative density varies from that required by the Soils Engineer, the Contractor should re-work the fill until the Soils Engineer approves it. H. Each layer shall be compacted to 90 percent of the maximum density in compliance with the testing method specified by the controlling governmental agency. (In general, ASTM D-1557, the five-layer method will be used.) If compaction to a lesser percentage is authorized by the controlling governmental agency because of a specific land use or expansive soils condition, the area to receive fill compacted to less than 90 percent shall either be delineated on the grading plan or appropriate reference made to the area in the soils report. I. All fills shall be keyed and benched through all topsoil, colluvium, alluvium or creep material, into sound bedrock or firm material except where the slope receiving fill exceeds a ratio of five horizontal to one vertical, in accordance with the recommendations of the Soils Engineer. J. The key for hillside fills should be a minimum of 15 feet in width and within bedrock or similar materials, unless otherwise specified in the soil report. K. Sub-drainage devices shall be constructed in compliance with the ordinances of the controlling governmental agency, or with the recommendations of the Soils Engineer or Engineering Geologist. L. The contractor will be required to obtain a minimum relative compaction of 90 percent out to the finish slope face of fill slopes, buttresses, and stabilization fills. This may be achieved by either overbuilding the slope and cutting back to the compacted core, or by direct compaction of the slope face with suitable equipment, or by any other procedure that produces the required compaction. M. All fill slopes should be planted or protected from erosion or by other methods specified in the soils report. 2 1· I I I I I I I I I I I I I I I I I I Appendix A STANDARD GRADING SPECIFICATIONS N. Fill-over-cut slopes shall be properly keyed through topsoil, colluvium or creep material into rock or firm materials, and the transition shall be stripped of all soil prior to placing fill. CUT SLOPES A. The Engineering Geologist shall insp·ect all cut slopes at vertical intervals not exceeding 10 feet. B. 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 Soils Engineer, and recommendations shall be made to treat these problems. C. Cut slopes that face in the same direction as the prevailing drainage shall be protected from slope wash by a non-erodible interceptor swale placed at the top of the slope. Unless otherwise specified in the soils and geological report, no cut slopes shall be excavated higher or steeper than that allowed by the ordinances of controlling governmental agencies. Drainage terraces shall be constructed in compliance with the ordinances of controlling governmental agencies, or with the recommendations of the Soils Engineer or Engineering Geologist. GRADING CONTROL AND COMPACTION TESTING A. Observation of the fill placement shall be provided by the Soils Engineer during the progress of grading. B. In general, density tests should be made at intervals not exceeding 2 feet of fill height or every 500 cubic yards of fill placement. These criteria will vary, depending on soil conditions and the size of the job. In any event, an adequate number of field density tests shall be made to verily that the required compaction is being achieved. C. Density tests may also be conducted on the surface material to receive fills as determined by the Soils Engineer. D. All clean-outs, processed ground to receive fill, key excavations, subdrains, and rock disposals must be inspected and approved by the Soils Engineer or Engineering Geologist prior to placing any fill. It shall be the Contractor's responsibility to notify the Soils Engineer when such areas are ready for inspection. CONSTRUCTION CONSIDERATIONS A. The Contractor shall provide necessary erosion control measures during grading and prior to the completion and construction of permanent drainage controls. B. Upon completion of grading and termination of inspections by the Soils Engineer, no further filling or excavating, including that necessary for footings, foundations, large tree wells, retaining walls, or other features shall be performed without the approval of the Soils Engineer or Engineering Geologist. C. Care shall be taken by the Contractor during final grading to preserve any berms, drainage terraces, interceptor swales, or other devices of permanent nature on or adjacent to the property. D. In the event that temporary ramps or pads are constructed of uncontrolled fill soils during a future grading operation, the on-site representative of a qualified soil-engineering firm shall note the location and extent of the loose fill soils. These materials shall be removed and properly recompacted prior to completion of grading opc1·atio11s. E. Where not superseded by specific recommendations presented in this report, trenches, excavations, and temporary slopes at the subject site shall be constructed in accordance with Section 1541 of Title 8, Construction Safety Orders, issued by OSHA. 3 I I I I I I I I I I I I I I I I I I I UNIFIED SOIL CLASSIFICATION CHART Appendix "B" SOI L DESC RI PTI ON I . COARSE GRAINED: More than half of material is larger than No. 200 sieve size. GRAVELS: More than half of coarse fraction is larger than No. 4 sieve size but smaller than 3". GROUP SYMBOL CLEAN GRAVELS GRAVELS WITH FINES (Appreciable amount offtnes) GW GP GM GC TYPICAL NAMES Well graded gravels, gravel-sand mixtures, little or no fines. Poorly graded gravels, gravel sand mixtures, little or no fines Silty gravels, poorly graded gravel-sand-silt mixtures Clayey gravels, poorly graded gravel sand, clay mixtures. SANDS: More than half of coarse fraction is smaller than No. 4 sieve size CLEAN SANDS SW SP SANDS WITH FINES SM (Appreciable amount of fines SC Well graded sand, gravelly sands, little or no fines Poorly graded sands, gravelly sands, little or no fines Silty sands, poorly graded sand and silty mixtures. Clayey sands, poorly graded sand and clay mixtures II. FINE GRAINED: More than half of material is smaller than No. 200 sieve size SILTS AND CLAYS Liquid Limit Less than 50 SILTS AND CLAYS Liquid Limit greater than 5 0 HIGHLY ORGANIC SOILS ML CL OL MH CH OH PT Inorganic silts and very fine sands, rock flour, sandy silt -or clayey-silt with slight plasticity. Inorganic clays of/ow to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays Organic silts and organic silty clays of low plasticity Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silt Inorganic clays of high plasticity,fat clays. Organic clays of medium to high plasticity. Peat and other ltig/zly organic soils.