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Home My WebLink AboutCDP 2020-0007; TERRA BELLA DEVELOPMENT; PRELIMINARY GEOTECHNICAL EVALUATION; 2019-03-09 PRELIMINARY GEOTECHNICAL EVALUATION FOR PROPOSED RESIDENTIAL DEVELOPMENT 6479 Surfside Lane CARLSBAD, CALIFORNIA PREPARED FOR Meng Xu P.O. Box 232458 Encinitas, California 920243 PREPARED BY GEOTEK, INC. 1384 POINSETTIA AVENUE, SUITE A VISTA, CALIFORNIA 92081 PROJECT NO 3630-SD MARCH 9, 2020 GEOTEK GEOTECHNICAL | ENVIRONMENTAL | MATERIALS March 9, 2019 Project No 3630-SD Terra Bella Development LLC P.O. Box 232458 Encinitas, California 920243 Attention: Ms. Meng Xu Subject: Preliminary Geotechnical Evaluation 6479 Surfside Lane Carlsbad, California Dear Ms. Xu: We are pleased to provide herein the results of our preliminary geotechnical evaluation for the subject project. This report presents the results of our evaluation and provides preliminary geotechnical recommendations for design and construction. In our opinion, site development appears feasible from a geotechnical viewpoint provided that the recommendations included herein are incorporated into the design and construction phases of site development. The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to call our office. Respectfully submitted, GeoTek, Inc. Christopher D. Livesey Benjamin R. Grenis CEG 2733, Exp. 05/30/21 RCE 83971, Exp. 09/30/21 Project Geologist Project Engineer Edward LaMont CEG 1892 Principal Geologist Distribution: (1) Addressee via email GeoTek, Inc. 1384 Poinsettia Avenue, Suite A Vista, CA 9208 1-8505 (760) 599-0509 (760) 599-0593 www.geotekusa.com GEOTECHNICAL I ENVIRONMENTAL I MATERIALS Terra Bella Development LLC Page i Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 TABLE OF CONTENTS 1. PURPOSE AND SCOPE OF SERVICES ................................................................................................. 1 2. SITE DESCRIPTION AND PROPOSED DEVELOPMENT ............................................................... 1 2.1 Site Description ................................................................................................................................ 1 2.2 Proposed Development ..................................................................................................................... 2 3. FIELD EXPLORATION AND LABORATORY TESTING ................................................................. 2 3.1 Field Exploration ............................................................................................................................... 2 3.2 Laboratory Testing ............................................................................................................................ 2 4. GEOLOGIC AND SOILS CONDITIONS ............................................................................................... 3 4.1 Regional Setting ................................................................................................................................ 3 4.2 EARTH MATERIALS ......................................................................................................................... 3 Artificial Fill ....................................................................................................................................... 3 Old Paralic Deposits.......................................................................................................................... 3 4.3 SURFACE WATER AND GROUNDWATER ........................................................................................ 4 Surface Water .................................................................................................................................. 4 Groundwater .................................................................................................................................... 4 4.4 EARTHQUAKE HAZARDS ................................................................................................................ 4 Surface Fault Rupture ....................................................................................................................... 4 Liquefaction/Seismic Settlement......................................................................................................... 4 Other Seismic Hazards ..................................................................................................................... 5 5. CONCLUSIONS AND RECOMMENDATIONS .................................................................................. 5 5.1 General ............................................................................................................................................ 5 5.2 EARTHWORK CONSIDERATIONS ................................................................................................... 5 General ............................................................................................................................................ 5 Site Clearing and Preparation ............................................................................................................ 5 Remedial Grading ............................................................................................................................. 6 Engineered Fill .................................................................................................................................. 6 Excavation Characteristics ................................................................................................................. 7 Temporary Shoring Design Parameters .............................................................................................. 7 Shrinkage and Bulking ...................................................................................................................... 7 Basement and Trench Excavations .................................................................................................... 7 Basement and Trench Backfill ........................................................................................................... 8 5.3 DESIGN RECOMMENDATIONS ....................................................................................................... 8 Stormwater Infiltration ...................................................................................................................... 8 Foundation Design Criteria ................................................................................................................ 8 Underslab Moisture Membrane....................................................................................................... 11 Miscellaneous Foundation Recommendations ................................................................................... 12 Foundation Set Backs...................................................................................................................... 12 Seismic Design Parameters ............................................................................................................. 12 Soil Sulfate Content ........................................................................................................................ 13 5.4 BASEMENT RETAINING WALL DESIGN AND CONSTRUCTION..................................................... 13 General Design Criteria ................................................................................................................... 13 Wall Backfill and Drainage ............................................................................................................. 14 Basement Retaining Wall Drainage (Sump System).......................................................................... 15 5.5 POST CONSTRUCTION CONSIDERATIONS ................................................................................... 15 4.1.! 4.2.2 4.3.! 4.3.1 4.4./ 4.4.2 4.4 . .1 .'i.2.i 5-2.2 5.23 5.2A 5.25 5,2.6 5.2] 5.2.B 5.2.9 53.I S3 . .2 53.3 5.3.4 53.5 53.6 5.3] 5A-.i 5A~'l 5A.3 GEOTEK Terra Bella Development LLC Page ii Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 TABLE OF CONTENTS Landscape Maintenance and Planting .............................................................................................. 15 Drainage ........................................................................................................................................ 16 5.6 PLAN REVIEW AND CONSTRUCTION OBSERVATIONS ................................................................. 16 6. LIMITATIONS ............................................................................................................................................ 17 7. SELECTED REFERENCES ....................................................................................................................... 18 ENCLOSURES Figure 1 – Site Location Map Figure 2 – Geotechnical Map Appendix A – Exploratory Boring Logs Appendix B – Results of Laboratory Testing Appendix C – General Earthwork Grading Guidelines 5.5.i 55.2 GEOTEK Terra Bella Development LLC Page 1 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 1. PURPOSE AND SCOPE OF SERVICES The purpose of this study was to evaluate the geotechnical conditions on the site. Services provided for this study included the following:  Research and review of available geologic and geotechnical data, and general information pertinent to the site.  Excavation of two (2) exploratory test borings onsite and collection of disturbed bulk and relatively undisturbed driven soil samples for subsequent laboratory testing.  Laboratory testing of select soil samples collected during the field investigation.  Review and evaluation of site seismicity  Compilation of this geotechnical report which presents our findings of pertinent site geotechnical conditions and geotechnical recommendations for site development. 2. SITE DESCRIPTION AND PROPOSED DEVELOPMENT 2.1 Site Description The subject project site is located at 6479 Surfside Lane in the city of Carlsbad, California (see Figure 1). The site is generally bounded to the east by Surfside Lane, to the west by Carlsbad Boulevard, to the north by a similar size vacant lot, and to the south by an existing single-family two stories above-grade residence. The site is located in a relatively flat topographic setting with lot drainage toward Surfside Lane. There are currently no improvements existing on-site with the exception of privacy walls separating the property from Carlsbad Boulevard to the west and the adjacent lots to the north and south. Site surface conditions generally consisted of weeds and grasses. Based on available aerial photographs the site has never been developed, with adjacent properties only being developed in the early 2000’s (~2002). Access is via a driveway off Surfside Lane. The site lies at an approximate elevation of 68 feet above sea level and expresses a total relief only on the order of a few feet. GEOTEK Terra Bella Development LLC Page 2 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 2.2 Proposed Development Based on review of the conceptual site plan prepared by Jack Bian (undated), proposed development will include a two-story single-family house with a roof top deck, basement, and an in ground lap pool in the basement. A two-car garage is proposed at the first floor, overlying the basement. Access to the site will continue to be provided by a driveway approach off Surfside Lane. The plan notes the driveway approach to be widened to the north 3 to 4 feet. The plan reviewed depicts site surface grades will be relatively unchanged. Associated improvements are anticipated to consist of wet and dry utilities, pavements, and landscaping. A copy of the plan provided is used as the base for the Geotechnical Map (Figure 2) included with this report. As site planning progresses and additional or revised plans become available, the plans should be provided to GeoTek for review and comment. Additional geotechnical field exploration, laboratory testing and engineering analyses may be necessary to provide specific earthwork recommendations and geotechnical design parameters for actual site development plans. 3. FIELD EXPLORATION AND LABORATORY TESTING 3.1 Field Exploration Our field exploration was conducted on February 17, 2020 and consisted of a site reconnaissance, excavation of two exploratory borings utilizing a rubber-tired truck mounted CME 95 hollow stem auger drilling rig. A Staff Geologist from our firm visually logged the borings and collected bulk and driven soil samples for laboratory analysis. Approximate locations of exploration locations are presented on the Geotechnical Map, Figure 2. A description of material encountered in the borings is included in Appendix A. 3.2 Laboratory Testing Laboratory testing was performed on bulk and relatively undisturbed soil samples collected during the field explorations. The purpose of the laboratory testing was to evaluate their physical and chemical properties for use in engineering design and analysis. Results of the laboratory testing program, along with a brief description and relevant information regarding testing procedures, are included in Appendix B. GEOTEK Terra Bella Development LLC Page 3 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 4. GEOLOGIC AND SOILS CONDITIONS 4.1 Regional Setting The subject property is located in the Peninsular Ranges geomorphic province, one of the largest geomorphic units in western North America. It extends roughly 975 miles from its northern extent where it is bounded by the west-northwest trending Transverse Ranges geomorphic province, to its southern edge at the tip of Baja California. The Peninsular Ranges vary in width from about 30 to 100 miles, bounded on the west by the Pacific Ocean and on the east by the Colorado Desert Province. The geomorphic province is characterized by a series of northwest-southeast oriented fault blocks with several major fault zones of renown residing here, all considered part of the greater San Andreas Fault System. The Elsinore Fault zone and the San Jacinto Fault zones are found near the center of the province, with the San Andreas Fault zone forming the northeasterly margin of the province. 4.2 EARTH MATERIALS A brief description of the earth materials encountered during our subsurface exploration is presented in the following sections. Based on our field observations and review of published geologic maps the subject site is locally underlain by artificial fill materials over paralic deposits (soft bedrock). Artificial Fill Artificial fill soils were locally observed as dark brown fine sands in the upper five feet of exploratory borings B-1 and B-2 and are assumed to be present throughout the site. Documentation of artificial fill soils have not been reviewed and thus are considered undocumented. It should be noted that reports regarding the investigation and subsequent construction of public roads for the subdivision (Surfside Lane) provide earthwork documentation for the road construction and improvements (Cardiff Geotechnical, 1993 and Law/Crandall 1996). Old Paralic Deposits The most recent regional geologic map showing the overall site geology (Kennedy, 2007), shows old paralic deposits, unit 6-7, at the surface across the site. Based on our site evaluation old paralic deposits are present beneath the artificial fill. In the borings, old paralic deposits were encountered as poorly graded light brown sand. Descriptions of the old paralic materials as encountered in our borings are shown on the boring logs included in Appendix A. 4.2.1 4.2.2 GEOTEK Terra Bella Development LLC Page 4 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 4.3 SURFACE WATER AND GROUNDWATER Surface Water Surface water was not observed during our site visit. If encountered during earthwork construction, surface water on this site is likely the result of precipitation or possibly some minor surface run-off from immediately surrounding properties. Provisions for surface drainage will need to be accounted by the project civil engineer. Groundwater Based on a review of previous work performed in the area (Alton Geoscience, 1990 & Cardiff Geotechnical, 1993), borings and test pits did not encounter groundwater within about 20 feet of the surface. Based on our recent borings, we did not encounter groundwater within 46.5 feet of the surface, as such, groundwater is not anticipated to be a factor in site development. Localized perched groundwater could be present but is also not anticipated to be a factor in site development. 4.4 EARTHQUAKE HAZARDS Surface Fault Rupture The geologic structure of the entire southern California area is dominated mainly by northwest- trending faults associated with the San Andreas system. The site is in a seismically active region. No active or potentially active fault is known to exist at this site nor is the site situated within an “Alquist-Priolo” Earthquake Fault Zone or a Special Studies Zone (Bryant and Hart, 2007). No faults are identified on the readily available geologic maps reviewed for the immediate study area. Liquefaction/Seismic Settlement Liquefaction describes a phenomenon in which cyclic stresses, produced by earthquake-induced ground motion, create excess pore pressures in relatively cohesionless soils. These soils may thereby acquire a high degree of mobility, which can lead to lateral movement, sliding, consolidation and settlement of loose sediments, sand boils and other damaging deformations. This phenomenon occurs only below the water table, but, after liquefaction has developed, the effects can propagate upward into overlying non-saturated soil as excess pore water dissipates. The factors known to influence liquefaction potential include soil type and grain size, relative density, groundwater level, confining pressures, and both intensity and duration of ground shaking. In general, materials that are susceptible to liquefaction are loose, saturated granular soils having low fines content under low confining pressures. 4.3.1 4.3.2 4.4.1 4.4.2 GEOTEK Terra Bella Development LLC Page 5 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 The liquefaction potential and seismic settlement potential on this site is considered negligible, due to the generally dense nature of old paralic deposits and absence of a shallow groundwater table underlying the site. Other Seismic Hazards Evidence of ancient landslides or slope instabilities at this site was not observed during our investigation. Thus, the potential for landslides is considered negligible. The potential for secondary seismic hazards such as seiche and tsunami is considered to be remote due to site elevation and distance from an open body of water, as confirmed by a review of the ASCE Tsunami Hazard Tool. 5. CONCLUSIONS AND RECOMMENDATIONS 5.1 General Development of the site appears feasible from a geotechnical viewpoint provided that the following recommendations are incorporated in the design and construction phases of the development. The following sections present general recommendations for currently anticipated site development plans. 5.2 EARTHWORK CONSIDERATIONS General Earthwork and grading should be performed in accordance with the applicable grading ordinances of the City of Carlsbad, the 2019 (or current) California Building Code (CBC), and recommendations contained in this report. The Grading Guidelines included in Appendix C outline general procedures and do not anticipate all site specific situations. In the event of conflict, the recommendations presented in the text of this report should supersede those contained in Appendix C. Site Clearing and Preparation Site preparation should start with removal of deleterious materials and vegetation. These materials should be disposed of properly off site. Any existing underground improvements, utilities and trench backfill should also be removed or be further evaluated as part of site development operations. 4.4.3 5.2.1 5.2.2 GEOTEK Terra Bella Development LLC Page 6 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 Remedial Grading Due to the planned basement, excavations for the structure are anticipated to remove the upper loose and compressible materials within the footprint of the structure and to the east and west due to temporary excavations for the basement construction. Recommendations for removals in areas to receive vehicular pavements and hardscape are provided below. Areas that will support pavements may not need complete removal of artificial fill to expose paralic deposits. If removal of unsuitable soils are not achieved with temporary excavations, we anticipate that excavations extending a minimum of one (1) foot below the bottom of the pavement subgrade will be adequate, subject to field verification. Where possible, overexcavations should extend a minimum of two (2) feet outside the proposed pavement envelope(s). Depending on actual field conditions encountered during grading, locally deeper and/or shallower areas of removal may be necessary. Temporary shoring is anticipated to be utilized for providing stability of the properties to the north and south of the site during basement construction. A conceptual temporary shoring plan was not provided for review, however we anticipate cantilevered soldier beams and wood lagging to be utilized. After removal or partial demolition of the temporary shoring, disturbed earthwork will need to be removed to undisturbed artificial fill or old paralic deposits. The intent of the recommended overexcavation is to support the improvements on engineered fill with relatively uniform engineering characteristics and decrease the potential for differential settlement. The bottom of all removals to receive fill should be scarified to a minimum depth of six (6) inches, brought to at or above optimum moisture content, and then compacted to minimum project standards prior to fill placement. The remedial excavation bottoms should be observed by a GeoTek representative prior to scarification. Any resultant voids from remedial grading/overexcavation should be filled with materials placed in general accordance with Section 5.2.4 Engineered Fill of this report. Engineered Fill Onsite materials remaining after site clearing are generally considered suitable for reuse as engineered fill provided they are free from vegetation, roots, debris, and rock/concrete or hard lumps greater than six (6) inches in maximum dimension. Engineered fill materials should be moisture conditioned to at or above optimum moisture content and compacted in horizontal lifts not exceeding 8 inch in loose thickness to a minimum 5.2.3 5.2.-4 GEOTEK Terra Bella Development LLC Page 7 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 relative compaction of 90% as determined in accordance with laboratory test procedure ASTM D 1557. Excavation Characteristics Excavations in the onsite artificial fill and old paralic materials can generally be accomplished with heavy-duty earthmoving or excavating equipment in good operating condition. Localized lenses of friable sands may be present and need to be shored at shorter intervals than other locations.. Temporary Shoring Design Parameters We anticipate that temporary shoring will be required to accommodate the construction of the proposed basement along the north and south property lines. Preliminarily, we have assumed that a soldier pile and lagging earth retention system will be used. Based on anticipated shored heights we have provided parameters for a cantilevered condition. Upon request, additional parameters can be provided for a raker-braced supported shoring wall. A cantilevered temporary shoring wall may be designed for active soil conditions using an equivalent fluid pressure of 40 pcf for a level backfill condition. These design values assume that a permeable wall facing (e.g. lagging) will effectively provide drainage and prevent the build-up of hydrostatic pressures. Lateral support may be derived by embedding the shoring elements into the underlying old paralic deposits using an allowable passive pressure of 240 psf/ft. For wall systems that derive their support from isolated pile conditions (e.g. soldier piles), an effective width of two times the soldier piles diameter may be used when calculating passive pressure. Design of lagging is the purview of the shoring designer, but may generally be designed using an applied earth pressure of 200 psf with spans of 8 feet or less. Shrinkage and Bulking Several factors will impact earthwork balancing on the site, including old paralic bulking, and possible shrinkage of undocumented fill, trench spoil from utilities and footing excavations, as well as the accuracy of topography. Due to the proposed basement excavation, shrinkage and bulking factors for balancing earthwork construction is considered to not be a factor, as the net balance is considered to be an export site. Basement and Trench Excavations Excavations to the east and west of the proposed basement are anticipated to be laid back in a temporary excavation to facilitate construction of the basement. Temporary excavations within the onsite materials should be stable at 1:1 inclinations for short durations during construction, and where cuts do not exceed 10 feet in height. Temporary cuts to a maximum height of 4 feet can be excavated vertically. 5.2,5 5.2.6 5.2.7 5.2.8 GEOTEK Terra Bella Development LLC Page 8 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 Trench excavations should conform to Cal-OSHA regulations. The contractor should have a competent person, per OSHA requirements, on site during construction to observe conditions and to make the appropriate recommendations. Basement and Trench Backfill Permanent basement wall backfill and utility trench backfill should be compacted to at least 90% relative compaction of the maximum dry density as determined per ASTM D 1557. Under-slab trenches should also be compacted to project specifications. Onsite materials may be suitable for use as bedding and shading material, subject to testing and provided particles larger than 1/8 inch are removed. Compaction should be achieved with a mechanical compaction device. Ponding or jetting of trench backfill is not recommended. If backfill soils have dried out, they should be thoroughly moisture conditioned prior to placement in trenches. 5.3 DESIGN RECOMMENDATIONS Stormwater Infiltration Many factors control infiltration of surface waters into the subsurface, such as consistency of native soils and bedrock, geologic structure, fill consistency, material density differences, and existing groundwater conditions. Preliminary plans do not show proposed locations for stormwater quality basins, however based on discussions with you, we understand that permeable pavers may be designed for the driveway. Due to the proposed basement construction, intentional infiltration of surface waters into the subsurface is not recommended. Filtration systems should be utilized for stormwater quality control. Pavers and permeable pavers should be underlain with an impermeable liner with underdrainage directed to a suitable outlet. Foundation Design Criteria Limited design criteria are presented for a basement foundation bearing into old paralic deposits. Basements are often designed using a monolithic mat slab to simultaneously support the retaining walls, structural loads, and provide a slab. However, the designer may also use some combination of continuous and spread footings with a slab-on-grade. Provided herein are limited and typical design criteria and will need additional design input by the structural engineer. Based on the results of our laboratory expansivity test result of zero (0) performed on sample BB1 at boring B-1, it is anticipated that the majority of the onsite soils to be encountered at 5.2,9 5.3.1 5.3.2 GEOTEK Terra Bella Development LLC Page 9 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 basement foundation depth may be classified as having a “Very Low” (EI<20) expansion potential per ASTM D 4829. Additional laboratory testing should be performed at the completion of site grading to verify the expansion potential and plasticity index of the subgrade soils. A summary of our limited design recommendations for conventionally reinforced basement foundation is presented in the table below: GEOTECHNICAL RECOMMENDATIONS FOR FOUNDATION DESIGN DESIGN PARAMETER “Very Low” Expansion Potential (EI <20) Foundation Depth or Minimum Perimeter Beam Depth (inches below lowest adjacent grade) Per Structural Design Minimum Foundation Width (inches)* Per Structural Design Minimum Non-Structural Slab Thickness (inches) (no loads from basement walls are applied to the slab) 4 (actual) Sand Blanket and Moisture Retardant Membrane Below On- Grade Building Slabs 2 inches of sand† overlying moisture vapor retardant membrane overlying 2 inches of sand ** Minimum Non-Structural Slab Reinforcing (no loads from basement walls are applied to the slab) No. 3 rebar 18-inches on-center, each way, placed in middle 1/3 of slab thickness Minimum Reinforcement for Continuous Footings, Grade Beams and Retaining Wall Footings Four (4) No. 4 Reinforcing Bars, two (2) top and two (2) bottom Effective Plasticity Index‡ 15 Presaturation of Subgrade Soil (Percent of Optimum/Depth in Inches) Minimum 100% to a minimum depth of 12 inches * Code minimums per Table 1809.7 of the 2019 CBC † Sand should have a Sand Equivalent of at least 30 ‡ Effective plasticity index should be verified upon excavation for basement It should be noted that the above recommendations are based on soil support characteristics only. The structural engineer should design the slab and beam reinforcement based on actual loading conditions. The following criteria for design of foundations should be implemented for the basement foundations:  An allowable bearing capacity of 3,000 pounds per square foot (psf) may be used for design of continuous footings 18 inches deep and 12 inches wide, and pad footings 24 inches square and 18 inches deep. All footing should a have a minimum of 12 inches GEOTEK Terra Bella Development LLC Page 10 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 embedment in the paralic deposits. This value may be increased by 300 pounds per square foot for each additional 12 inches in depth and 100 pounds per square foot for each additional 12 inches in width to a maximum value of 3,500 psf. Additionally, an increase of one-third may be applied when considering short-term live loads (e.g. seismic and wind loads).  The recommended allowable bearing capacity is based on a total post-construction settlement of one (1) inch. Differential settlement of up to one-half of the total settlement over a horizontal distance of 40 feet could result.  Spread footings for an individual structure should be tied together in two orthogonal directions with either reinforced grade-beams and/or continuous footings to provide a more rigid and monolithic shallow foundation system.  The passive earth pressure may be computed as an equivalent fluid having a density of 240 psf per foot of depth, to a maximum earth pressure of 2,500 psf for footings founded in engineered fill. A coefficient of friction between engineered fill and concrete of 0.35 may be used with dead load forces. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. Foundations for smaller secondary walls founded in engineered fill may be designed using the following parameters:  An allowable bearing capacity of 2,000 pounds per square foot (psf) may be used for design of continuous footings 12 inches deep and 12 inches wide, all footing should have a minimum of 12 inches soil embedment. This value may be increased by 200 pounds per square foot for each additional 12 inches in depth and 100 pounds per square foot for each additional 12 inches in width to a maximum value of 2,500 psf. Additionally, an increase of one-third may be applied when considering short-term live loads (e.g. seismic and wind loads).  The recommended allowable bearing capacity is based on a total post-construction settlement of one (1) inch. Differential settlement of up to one-half of the total settlement over a horizontal distance of 40 feet could result.  The passive earth pressure may be computed as an equivalent fluid having a density of 240 psf per foot of depth, to a maximum earth pressure of 2,000 psf for footings founded in engineered fill. A coefficient of friction between engineered fill and concrete of 0.35 may be used with dead load forces. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. GEOTEK Terra Bella Development LLC Page 11 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 Underslab Moisture Membrane In the event the basement is not fully waterproofed and is instead provided with a backdrain and sump system, the basement slab should be constructed with an underslab moisture membrane, as discussed in this section. A moisture and vapor retarding system should be placed below slabs-on-grade where moisture migration through the slab is undesirable. Guidelines for these are provided in the 2019 California Green Building Standards Code (CALGreen) Section 4.505.2 and the 2019 CBC Section 1907.1 It should be realized that the effectiveness of the vapor retarding membrane can be adversely impacted as a result of construction related punctures (e.g. stake penetrations, tears, punctures from walking on the vapor retarder placed atop the underlying aggregate layer, etc.). These occurrences should be limited as much as possible during construction. Thicker membranes are generally more resistant to accidental puncture that thinner ones. Products specifically designed for use as moisture/vapor retarders may also be more puncture resistant. Although the CBC specifies a 6 mil vapor retarder membrane, it is GeoTek’s opinion that a minimum 10 mil membrane with joints properly overlapped and sealed should be considered, unless otherwise specified by the slab design professional. Moisture and vapor retarding systems are intended to provide a certain level of resistance to vapor and moisture transmission through the concrete, but do not eliminate it. The acceptable level of moisture transmission through the slab is to a large extent based on the type of flooring used and environmental conditions. Ultimately, the vapor retarding system should be comprised of suitable elements to limit migration of water and reduce transmission of water vapor through the slab to acceptable levels. The selected elements should have suitable properties (i.e. thickness, composition, strength and permeability) to achieve the desired performance level. Moisture retarders can reduce, but not eliminate, moisture vapor rise from the underlying soils up through the slab. Moisture retarder systems should be designed and constructed in accordance with applicable American Concrete Institute, Portland Cement Association, Post- Tensioning Concrete Institute, ASTM and California Building Code requirements and guidelines. GeoTek does not practice in the field of moisture vapor transmission evaluation/migration, since that practice is not a geotechnical discipline. Therefore, we recommend that a qualified person, such as the flooring contractor, structural engineer, architect, and/or other experts specializing in moisture control within the building be consulted to evaluate the general and specific moisture and vapor transmission paths and associated potential impact on the proposed construction. That person (or persons) should provide recommendations relative to the slab moisture and vapor retarder systems and for migration of potential adverse impact of moisture vapor transmission 5.3.3 GEOTEK Terra Bella Development LLC Page 12 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 on various components of the structures, as deemed appropriate. In addition, the recommendations in this report and our services in general are not intended to address mold prevention; since we, along with geotechnical consultants in general, do not practice in the area of mold prevention. If specific recommendations addressing potential mold issues are desired, then a professional mold prevention consultant should be contacted. We recommend that control joints be placed in two directions spaced the numeric equivalent roughly 24 times the thickness of the slab in inches (e.g. a 4 inch slab would have control joints at 96 inch [8 feet] centers). These joints are a widely accepted means to control cracks and should be reviewed by the project structural engineer. Miscellaneous Foundation Recommendations  To reduce moisture penetration beneath the slab on grade areas, utility trenches should be backfilled with engineered fill, lean concrete or concrete slurry where they intercept the perimeter footing or thickened slab edge.  Spoils from the footing excavations should not be placed in the slab-on-grade areas unless properly compacted and tested. The excavations should be free of loose/sloughed materials and be neatly trimmed at the time of concrete placement. Foundation Set Backs Where applicable, the following setbacks should apply to all foundations. Any improvements not conforming to these setbacks may be subject to lateral movements and/or differential settlements:  The bottom of all footings for structures near retaining walls should be deepened so as to extend below a 1:1 projection upward from the bottom inside edge of the wall stem. This applies to the existing retaining walls along the perimeter, if they are to remain.  The bottom of any existing foundations for structures should be deepened so as to extend below a 1:1 projection upward from the bottom of the nearest excavation. Seismic Design Parameters The site is located at approximately 33.1111° Latitude and -117.3218° Longitude. Site spectral accelerations (Sa and S1), for 0.2 and 1.0 second periods for a Class “C” site, was determined from the SEAOC/OSHPD web interface that utilizes the USGS web services and retrieves the seismic design data and presents that information in a report format. Based on the presence of 5.3.4 5.3.5 5.3.6 GEOTEK Terra Bella Development LLC Page 13 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 shallow old paralic deposits, a Site Class C is deemed appropriate for this site. The results, based on ASCE 7-16 and the 2019 CBC, are presented in the following table. SITE SEISMIC PARAMETERS Mapped 0.2 sec Period Spectral Acceleration, Ss 1.137g Mapped 1.0 sec Period Spectral Acceleration, S1 0.408g Site Coefficient for Site Class “C,” Fa 1.2 Site Coefficient for Site Class “C,” Fv 1.5 Maximum Considered Earthquake Spectral Response Acceleration for 0.2 Second, SMS 1.365g Maximum Considered Earthquake Spectral Response Acceleration for 1.0 Second, SM1 0.612g 5% Damped Design Spectral Response Acceleration Parameter at 0.2 Second, SDS 0.91g 5% Damped Design Spectral Response Acceleration Parameter at 1 second, SD1 0.408g Peak Ground Acceleration Adjusted for Site Class Effects, PGAM 0.607g Final selection of the appropriate seismic design coefficients should be made by the project structural engineer based upon local practices and ordinances, expected building response and desired level of conservatism. Soil Sulfate Content The sulfate content was determined in the laboratory for a soil sample collected during the field investigation. The results indicate that the water soluble sulfate is less than 0.1 percent by weight, which is considered “S0” as per Table 19.3.1.1 of ACI 318-14, as such no special recommendations for concrete are included herein. 5.4 BASEMENT RETAINING WALL DESIGN AND CONSTRUCTION General Design Criteria Base on a review of project plans, basement retaining walls are anticipated to underly the footprint of the structure. Recommendations presented herein may apply to typical masonry or concrete vertical retaining walls to a maximum height of 15 feet. Additional review and recommendations should be requested for higher walls. Basement retaining wall foundations embedded a minimum of 18 inches into engineered fill or dense formational materials should be designed using an allowable bearing capacity of 3000 psf. 5.3.7 5.4.1 GEOTEK Terra Bella Development LLC Page 14 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 An increase of one-third may be applied when considering short-term live loads (e.g. seismic and wind loads). The passive earth pressure may be computed as an equivalent fluid having a density of 250 psf per foot of depth, to a maximum earth pressure of 2500 psf. A coefficient of friction between soil and concrete of 0.35 may be used with dead load forces. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one- third. An equivalent fluid pressure approach may be used to compute the horizontal active pressure against the wall. Basement retaining walls should be designed for at-rest soil conditions using an equivalent fluid pressure appropriate for the drainage scheme employed in the design and construction of the basement:  A foundation retaining wall provided with a backdrain and sump system may be designed using an equivalent fluid pressure of 60 pcf (select/onsite backfill)  A fully waterproofed retaining wall without a backdrain and sump system may be designed using an equivalent fluid pressure of 90 pcf (select/onsite backfill). These design pressures have been derived using only soil properties and do not include any applicable surcharge loading. The wall designer should include superimposed loading conditions due to vehicular traffic and structures. Wall Backfill and Drainage Wall backfill (including basement retaining walls not designed for hydrostatic pressures) should include a minimum one (1) foot wide section of ¾ to 1-inch clean crushed rock (or approved equivalent). The rock should be placed immediately adjacent to the back of wall and extend up from the backdrain to within approximately 12 inches of finish grade. The upper 12 inches should consist of compacted onsite materials. If the walls are designed using the “select” backfill design parameters, then the “select” materials shall be placed within the active zone as defined by a 1:1 (H:V) projection from the back of the retaining wall footing up to the retained surface behind the wall. Presence of other materials might necessitate revision to the parameters provided and modification of wall designs. The backfill materials should be placed in lifts no greater than 8-inches in thickness and compacted to a minimum of 90% of the maximum dry density as determined in accordance with ASTM Test Method D 1557. Proper surface drainage needs to be provided and maintained. Water should not be allowed to pond behind retaining walls. Waterproofing of site walls should be performed where moisture migration through the wall is undesirable. 5.4.2 GEOTEK Terra Bella Development LLC Page 15 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 Basement Retaining Wall Drainage (Sump System) In the event the basement retaining walls will be provided with a backdrain and sump system, the following recommendations should be utilized: Retaining walls should be provided with an adequate pipe and gravel back drain system to reduce the potential for hydrostatic pressures to develop. A 4-inch diameter perforated collector pipe (Schedule 40 PVC, or approved equivalent) in a minimum of one (1) cubic foot per lineal foot of 3/8 to one (1) inch clean crushed rock or equivalent, wrapped in filter fabric should be placed near the bottom of the backfill and be directed (via a solid outlet pipe) to an appropriate disposal area. Perched groundwater is common at geologic boundaries of inconsistent soil properties, such as artificial fills over undisturbed soils or formational/bedrock. Perched groundwater may develop into a nuisance condition if water proofing is not effectively applied. Perched groundwater may become a structural concern if allowed to appreciably build up behind the basement walls. Therefore, sump pumps to convey possible periodic perched groundwater away from the basement walls are recommended at low points surrounding the outside basement walls. Drain outlets should be maintained over the life of the project and should not be obstructed or plugged by adjacent improvements. 5.5 POST CONSTRUCTION CONSIDERATIONS Landscape Maintenance and Planting Water has been shown to weaken the inherent strength of soil, and slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from graded slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Controlling surface drainage and runoff, and maintaining a suitable vegetation cover can minimize erosion. Plants selected for landscaping should be lightweight, deep-rooted types that require little water and are capable of surviving the prevailing climate. Overwatering should be avoided. The soils should be maintained in a solid to semi-solid state as defined by the materials Atterberg Limits. Care should be taken when adding soil amendments to avoid excessive watering. Leaching as a method of soil preparation prior to planting is not recommended. An abatement program to control ground-burrowing rodents should be implemented and maintained. This is critical as burrowing rodents can decreased the long-term performance of slopes. 5.4.3 5.5.1 GEOTEK Terra Bella Development LLC Page 16 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 It is common for planting to be placed adjacent to structures in planter or lawn areas. This will result in the introduction of water into the ground adjacent to the foundation. This type of landscaping should be avoided. If used, then extreme care should be exercised with regard to the irrigation and drainage in these areas. Waterproofing of the foundation and/or subdrains is advised. We could discuss these issues, if desired, when plans are made available. Drainage The need to maintain proper surface drainage and subsurface systems cannot be overly emphasized. Positive site drainage should be maintained at all times. Water should be directed away from foundations toward approved infiltration basins and not allowed to pond or seep into the ground. Pad drainage should be directed toward approved area(s) and not be blocked by other improvements. It is the owner’s responsibility to maintain and clean drainage devices on or contiguous to their lot. In order to be effective, maintenance should be conducted on a regular and routine schedule and necessary corrections made prior to each rainy season. 5.6 PLAN REVIEW AND CONSTRUCTION OBSERVATIONS We recommend that changes to site grading, specifications, and any retaining wall/shoring plans and foundation plans be reviewed by this office prior to construction to check for conformance with the recommendations of this report. Additional recommendations may be necessary based on these reviews. We also recommend that GeoTek representatives be present during site grading and foundation construction to check for proper implementation of the geotechnical recommendations. The owner/developer should have GeoTek’s representative perform at least the following duties:  Observe site clearing and grubbing operations for proper removal of unsuitable materials.  Observe and test bottom of removals prior to fill placement.  Evaluate the suitability of on-site and import materials for fill placement, and collect soil samples for laboratory testing when necessary.  Observe the fill for uniformity during placement including utility trenches.  Observe and test the fill for field density and relative compaction.  Observe and probe foundation excavations to confirm suitability of bearing materials. If requested, a construction observation and compaction report can be provided by GeoTek, which can comply with the requirements of the governmental agencies having jurisdiction over 5.5.2 GEOTEK Terra Bella Development LLC Page 17 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 the project. We recommend that these agencies be notified prior to commencement of construction so that necessary grading permits can be obtained. 6. LIMITATIONS The scope of our evaluation is limited to the area explored that is shown on the Boring Location Map (Figure 2). This evaluation does not and should in no way be construed to encompass any areas beyond the specific area of proposed construction as indicated to us by the client. Further, no evaluation of any existing site improvements is included. The scope is based on our understanding of the project and the client’s needs, our proposal (Proposal No. P-02004-SD) dated February 12, 2020 and geotechnical engineering standards normally used on similar projects in this region. The materials observed on the project site appear to be representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during site construction. Site conditions may vary due to seasonal changes or other factors. GeoTek, Inc. assumes no responsibility or liability for work, testing or recommendations performed or provided by others. Since our recommendations are based on the site conditions observed and encountered, and laboratory testing, our conclusions and recommendations are professional opinions that are limited to the extent of the available data. Observations during construction are important to allow for any change in recommendations found to be warranted. These opinions have been derived in accordance with current standards of practice and no warranty is expressed or implied. Standards of practice are subject to change with time. GEOTEK Terra Bella Development LLC Page 18 Preliminary Geotechnical Evaluation Project No. 3630-SD 6479 Surfside Lane, Carlsbad, California March 9, 2020 7. SELECTED REFERENCES Alton Geoscience, 1990, “Site Characterization Report, Texaco Refining and Marketing Inc., 665 Palomar Airport Road, Carlsbad, California, 92009”, dated June 15, 1990. American Society of Civil Engineers (ASCE), 2016, “Minimum Design Loads for Buildings and Other Structures,” ASCE/SEI 7-16. ASTM International (ASTM), “ASTM Volumes 4.08 and 4.09 Soil and Rock.” Bryant, W.A., and Hart, E.W., 2007, "Fault Rupture Hazard Zones in California, Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zones Maps," California Geological Survey: Special Publication 42. California Code of Regulations, Title 24, 2019 “California Building Code,” 2 volumes. California Geological Survey (CGS, formerly referred to as the California Division of Mines and Geology), 1977, “Geologic Map of California.” ____, 1998, “Maps of Known Active Fault Near-Source Zones in California and Adjacent Portions of Nevada,” International Conference of Building Officials. Cardiff Geotechnical, 1993, “Preliminary Geotechnical Investigation, Proposed Street Development, La Costa Downs, SP-201, Carlsbad, California”, Work Order No. P-108073, dated August 3, 1993. GeoTek, Inc., In-house proprietary information. HWL Planning & Engineering, 2020, Preliminary Grading Plan for 6479 Surfside Lane, Carlsbad, CA, 92011, 1 Sheet, plot dated March 5, 2020. Jack Bian Architect, 2020, Architectural Plans for Surfside Family Residence, 6479 Surfside Lane, Carlsbad, CA 92011, 8 Sheets, A2-101 through A3-102, received February 2020. Kennedy, M.P., and Tan, S.S., 2007, “Geologic Map of the Oceanside 30x60-minute Quadrangle, California,” California Geological Survey, Regional Geologic Map No. 2, map scale 1:100,000. Law/Crandall, 1996, Reports of Field Density Testing and Laboratory Testing Associated with La Costa Downs Street Construction, various dates. Structural Engineers Association of California/California Office of Statewide Health Planning and Development (SEOC/OSHPD), 2020, Seismic Design Maps web interface, accessed March 5, 2020 at https://seismicmaps.org GEOTEK Terra Bella Development LLC 6479 Surfside Lane Carlsbad, California 1384 Poinsettia Avenue, Suite A Vista, California 92081 Figure 1 Site Location Map N Not to Scale Imagery from US Forestry Service, 2020 Approximate Site Location PN: 3630-SD DATE: March 2020 GEOTEK B-1B-2AfAfQopQopQopAfB-2Quaternary Old Paralic Deposits,Circled where BuriedArtifical FillApproximate Location of BoringLEGENDApproximate Limits of Study1384 Poinsettia Avenue, Suite AVista, California 92081NFigure 2Geotechnical MapPlan adapted from "Site Plan" by Jack Bian, Architect0 5 1020Scale: 1" = 10'Terra Bella Development LLC6479 Surfside LaneCarlsbad, CaliforniaPN: 3630-SD DATE: March 2020LEGEND rn: rap OF WALL r c: TOP a, CURB FL FLOWUNE. GEOTEK APPENDIX A EXPLORATORY BORING LOGS GEOTEK TERRA BELLA DEVELOPMENT LLC Project No 3630-SD Preliminary Geotechnical Evaluation March 9, 2020 6479 Surfside Lane, Carlsbad, California Page A-1 A - FIELD TESTING AND SAMPLING PROCEDURES The Modified Split-Barrel Sampler (Ring) The Ring sampler is driven into the ground in accordance with ASTM Test Method D 3550. The sampler, with an external diameter of 3.0 inches, is lined with 1-inch long, thin brass rings with inside diameters of approximately 2.4 inches. The sampler is typically driven into the ground 12 or 18 inches with a 140- pound hammer free falling from a height of 30 inches. Blow counts are recorded for every 6 inches of penetration as indicated on the log of boring. The samples are removed from the sample barrel in the brass rings, sealed, and transported to the laboratory for testing. Bulk Samples (Large) These samples are normally large bags of earth materials over 20 pounds in weight collected from the field by means of hand digging or exploratory cuttings. Bulk Samples (Small) These are plastic bag samples which are normally airtight and contain less than 5 pounds in weight of earth materials collected from the field by means of hand digging or exploratory cuttings. These samples are primarily used for determining natural moisture content and classification indices. B –EXPLORATION LOG LEGEND The following abbreviations and symbols often appear in the classification and description of soil and rock on the logs of borings and trenches: SOILS USCS Unified Soil Classification System f-c Fine to coarse f-m Fine to medium GEOLOGIC B: Attitudes Bedding: strike/dip J: Attitudes Joint: strike/dip C: Contact line ……….. Dashed line denotes USCS material change Solid Line denotes unit / formational change Thick solid line denotes end of boring (Additional denotations and symbols are provided on the logs) GEOTEK GeoTek, Inc. LOG OF EXPLORATORY BORING 4 R1 SP 6.4 111.9 8 Medium SAND, light brown to reddish, moist, medium dense, highly friable 11 EI, SR BB1 9 S1 13 15 7 R2 4.6 101.2 14 18 5 S2 8 12 10 R3 3.1 100.3 16 45 ---Small Bulk ---No Recovery ---Water Table AL = Atterberg Limits EI = Expansion Index SA = Sieve Analysis RV = R-Value Test SR = Sulfate/Resisitivity Test SH = Shear Test CO = Consolidation test MD = Maximum Density 30 LEGENDSample type: ---Ring ---SPT ---Large Bulk Lab testing: 25 Medium SAND, white, moist, very dense, highly friable, bottom of shoe contained small amounts of grey, dense clay 20 Coarse SAND, white, dry-slightly moist, medium dense, highly friable, high mafic content dense, high mafic mineral quantity 15 Medium coarse SAND, light tan with red motteling throughout, moist, medium Cuttings turned color to a lighter brown sand 10 Medium coarse SAND, light brown with reddish hues, moist, dense, highly Dark brown, loamy moist cuttings friable, motteling 5 Old Paralic Deposits Dry Density (pcf)Others MATERIAL DESCRIPTION AND COMMENTS Artifical Fill SAMPLES USCS Symbol BORING NO.: B-1 Laboratory Testing Depth (ft)Sample TypeBlows/ 6 inSample NumberWater Content (%)LOCATION:See Geotechnical Map ELEVATION:~68 msl DATE:2/17/2020 PROJECT NO.:3630-SD HAMMER:140lbs/30in RIG TYPE:CME 95 PROJECT NAME:Surfside Lane DRILL METHOD:8" HSA 3.75" ID OPERATOR:Manuel CLIENT:Terra Bella Development LLC DRILLER:Baja Exploration LOGGED BY:MSB --------- \~ --r --------- ------ ~I ------ --------• I [Z] ~ □ ¥ GeoTek, Inc. LOG OF EXPLORATORY BORING 14 S3 14 14 9 S4 12 15 15 S5 18 25 ---Small Bulk ---No Recovery ---Water Table AL = Atterberg Limits EI = Expansion Index SA = Sieve Analysis RV = R-Value Test SR = Sulfate/Resisitivity Test SH = Shear Test CO = Consolidation test MD = Maximum Density 60 LEGENDSample type: ---Ring ---SPT ---Large Bulk Lab testing: 55 50 No groundwater encountered Backfilled with soil cuttings 45 HOLE TERMINATED AT 41.5 FEET 40 Fine SAND, brown with medium reddish mottlight throughout, dry to slightly moist, very dense, relatively denser than previous samples yet still largely friable 35 Fine SAND, brown, dense, red mottling throughout, some pockets of white sand also throughout, highly friable Dry Density (pcf)Others MATERIAL DESCRIPTION AND COMMENTS Fine-medium SAND, white, slightly moist, dense, brown-red mottling highly prevalent SAMPLES USCS SymbolBORING NO.: B-1 (continued) Laboratory Testing Depth (ft)Sample TypeBlows/ 6 inSample NumberWater Content (%)LOCATION:See Geotechnical Map ELEVATION:~68 msl DATE:2/17/2020 PROJECT NO.:3630-SD HAMMER:140lbs/30in RIG TYPE:CME 95 PROJECT NAME:Surfside Lane DRILL METHOD:8" HSA 3.75" ID OPERATOR:Manuel CLIENT:Terra Bella Development LLC DRILLER:Baja Exploration LOGGED BY:MSB ~I ----- ~I ------ ~I --------------------------------------• I [Z] ~ □ ¥ GeoTek, Inc. LOG OF EXPLORATORY BORING 7 R1 SP 9 13 7 R2 6.1 105.6 SH 18 27 6 S1 9 10 5 S2 8 8 5 S3 8 9 ---Small Bulk ---No Recovery ---Water Table AL = Atterberg Limits EI = Expansion Index SA = Sieve Analysis RV = R-Value Test SR = Sulfate/Resisitivity Test SH = Shear Test CO = Consolidation test MD = Maximum Density 30 LEGENDSample type: ---Ring ---SPT ---Large Bulk Lab testing: 25 Coarse-medium SAND, white, slightly moist, medium dense, olive pale color, offwhite, friable and moist with high mafic content Cuttings turned slightly olive-green/white 20 Coarse-medium SAND, white, moist, medium dense, friable and moist, finer grained lenses of dark grey silty-fine sand, high in mafics 15 Coarse-medium SAND, white, red mottling throughout, moist, medium dense, high mafic content, top of sample contains brown sand, halfway down sample color changes to a coarse white sand, friable Cuttings turned color to a lighter brown sand 10 Medium-fine SAND, brown with red mottling throughout, moist, very dense, friable 5 Old Paralic Deposits Fine-medium SAND, brown, moist, medium dense, friable, some minor induration Dark brown, loamy moist cuttings Dry Density (pcf)Others MATERIAL DESCRIPTION AND COMMENTS Artificial Fill SAMPLES USCS Symbol BORING NO.: B-2 Laboratory Testing Depth (ft)Sample TypeBlows/ 6 inSample NumberWater Content (%)LOCATION:See Geotechnical Map ELEVATION:~68 msl DATE:2/17/2020 PROJECT NO.:3630-SD HAMMER:140lbs/30in RIG TYPE:CME 95 PROJECT NAME:Surfside Lane DRILL METHOD:8" HSA 3.75" ID OPERATOR:Manuel CLIENT:Terra Bella Development LLC DRILLER:Baja Exploration LOGGED BY:MSB --------- ------ ------ ~I ------ ~I ------ --------• I [Z] ~ □ ¥ GeoTek, Inc. LOG OF EXPLORATORY BORING 9 S4 12 13 13 S5 18 20 15 S6 22 23 ---Small Bulk ---No Recovery ---Water Table PROJECT NAME:Surfside Lane DRILL METHOD:8" HSA 3.75" ID OPERATOR:Manuel CLIENT:Terra Bella Development LLC DRILLER:Baja Exploration LOGGED BY:MSB LOCATION:See Geotechnical Map ELEVATION:~68 msl DATE:2/17/2020 PROJECT NO.:3630-SD HAMMER:140lbs/30in RIG TYPE:CME 95 SAMPLES USCS SymbolBORING NO.: B-2 (continued) Laboratory Testing Depth (ft)Sample TypeBlows/ 6 inSample NumberWater Content (%)Medium to fine SAND, pale white to light gray, moist, dense, highly friable Dry Density (pcf)Others MATERIAL DESCRIPTION AND COMMENTS 35 towards shoe 40 Medium-fine SAND, light brown, moist, dense, friable, some red mottling HOLE TERMINATED AT 46.5 FEET No groundwater encountered Backfilled with soil cuttings 45 Medium-fine SAND, white, slightly moist, very dense, friable, top of sample contains reddish oxidized nodules of rounded black silty-fine sand beads 50 55 AL = Atterberg Limits EI = Expansion Index SA = Sieve Analysis RV = R-Value Test SR = Sulfate/Resisitivity Test SH = Shear Test CO = Consolidation test MD = Maximum Density 60 LEGENDSample type: ---Ring ---SPT ---Large Bulk Lab testing: ~I --------------- ~I ------ ~I ----------------------------• I [Z] ~ □ ¥ APPENDIX B RESULTS OF LABORATORY TESTING GEOTEK TERRA BELLA DEVELOPMENT LLC Project No 3630-SD Preliminary Geotechnical Evaluation March 9, 2020 6479 Surfside Lane, Carlsbad, California Page B-1 SUMMARY OF LABORATORY TESTING Identification and Classification Soils were identified visually in general accordance to the standard practice for description and identification of soils (ASTM D2488). The soil identifications and classifications are shown on the logs of exploratory borings in Appendix A. In-Situ Moisture and Density The natural water content was determined (ASTM D 2216) on samples of the materials recovered during the subsurface exploration. In addition, in-place dry density determinations (ASTM D 2937) were performed on relatively undisturbed samples to measure the unit weight of the subsurface soils. Results of these tests are shown on the boring logs at the appropriate sample depths in Appendix A. Expansion Index Expansion Index testing was performed on one soil sample. Testing was performed in general accordance with ASTM Test Method D 4829. Results are presented in Appendix B. Shear Strength Shear Strength of site material was evaluated for an “undisturbed” sample. Testing was in general conformance with ASTM Test Method D3080. Results are presented in Appendix B. Sulfate Content Sulfate content was tested by a subconsultant specializing in corrosion engineering. Results of testing are presented at the rear of this appendix. GEOTEK Ring #: Ring Dia. :Ring Ht.:1"A Weight of compacted sample & ring (gm)B Weight of ring (gm)C Net weight of sample (gm)D E F Moisture Content, %G Specific Gravity, assumedH Unit Wt. of Water @ 20°C, (pcf)I % Saturation EXPANSION INDEX TEST(ASTM D4829)Client:Bella Terra DevelopmentTested/ Checked By:DA Lab No CoronaProject Number:3630-SDDate Tested:3/2/2020Project Location:Surfside LaneSample Source:B-1 @ 5 - 10Sample Description:4.01"362.6 DATE TIME READING3/2/2020 9:53 0.1240 InitialDENSITY DETERMINATION784.5READINGSWet Density, lb / ft3 (C*0.3016)127.210:03 0.1240 10 min/Dry421.9 Dry Density, lb / ft3 (D/1.F)117.8SATURATION DETERMINATION2.703/3/2020 10:03 0.1240 Final8.062.450.2 FINAL MOISTUREFinal Weight of wet sample & tare % Moisture805.813.0EXPANSION INDEX =0GEOTEK --I Sample Location: Date Tested: Shear Strength:F =29.3 O , C = 324.00 psf Notes: Project Name: Project Number: Surfside Lane 3630-SD DIRECT SHEAR TEST 3 - The tests were run at a shear rate of 0.035 in/min. B-2 @ 10 3/2/2020 1 - The soil specimens sheared were "undisturbed" ring samples. 2 - The above reflect direct shear strength at saturated conditions. PEAK VALUE 0.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 0.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0SHEAR STRESS (psf)NORMAL STRESS (psf) GEOTEK ------------,-------------r------------,------------~-------------r------------,-------------T-------------, I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ------------◄-------------~------------..... ------------·-------------~------------~-------------·--------1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ------------➔-------------~------------+------------+-------------~-----------'-------------+-------------! 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B-2 @ 10 3/2/2020 1 - The soil specimens sheared were "undisturbed" ring samples. 2 - The above reflect direct shear strength at saturated conditions. 0.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 0.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.0SHEAR STRESS (psf)NORMAL STRESS (psf) GEOTEK ------------,-------------r------------,------------~-------------r------------,-------------T-------------, I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ------------◄-------------~------------..... ------------·-------------~------------~-------------·-------------· I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ------------➔-------------~------------+------------4-------------~------------~-----I I ------+------------~ t I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ------------◄-------------~------------~------------•----------►------------◄-------------♦-------------• ' I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ------------➔-------------~------------I ----------+-------------~------------~-------------+-------------! I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ------------◄-----' I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ------~-------------+-------------•-------------►------------◄-------------♦-------------• I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Project X REPORT S200218B Corrosion Engineering Page 1 Corrosion Control – Soil, Water, Metallurgy Testing Lab 29990 Technology Dr, Suite 13, Murrieta, CA 92563 Tel: 213-928-7213 Fax: 951-226-1720 www.projectxcorrosion.com Results Only Soil Testing for Surfside Lane February 21, 2020 Prepared for: Chris Livesey GeoTek, Inc. 1384 Poinsettia Ave, Suite A Vista, CA, 92081 clivesey@geotekusa.com Project X Job#: S200218B Client Job or PO#: 3630-SD Respectfully Submitted, Eduardo Hernandez, M.Sc., P.E. Sr. Corrosion Consultant NACE Corrosion Technologist #16592 Professional Engineer California No. M37102 ehernandez@projectxcorrosion.com Project X REPORT S200218B Corrosion Engineering Page 2 Corrosion Control – Soil, Water, Metallurgy Testing Lab 29990 Technology Dr., Suite 13, Murrieta, CA 92563 Tel: 213-928-7213 Fax: 951-226-1720 www.projectxcorrosion.com Soil Analysis Lab Results Client: GeoTek, Inc. Job Name: Surfside Lane Client Job Number: 3630-SD Project X Job Number: S200218B February 21, 2020 Method Bore# / Description Depth (ft)(mg/kg)(wt%) B-1, BB-1 5.0-10.0 30.0 0.0030 ASTM D4327 Sulfates SO42- Cations and Anions, except Sulfide and Bicarbonate, tested with Ion Chromatography mg/kg = milligrams per kilogram (parts per million) of dry soil weight ND = 0 = Not Detected | NT = Not Tested | Unk = Unknown Chemical Analysis performed on 1:3 Soil-To-Water extract ►•◄ Project X . orrosion Engineering • t ""' ,i,,n \ ·,,,1111,,J '<'Iii \t lll:f' .u J \l";ailhu)I:,-I lllb Project X Job Number S 2..o02/J 'B G,eo+d Lab Request Sheet Chain of Custody Phone: (2 13) 928-72 13 · Fax (95 1) 226-1720 · www.projcctxcorrosion.com Ship Samples To: 29990 Technology Dr, Suite 13, Murrieta, CA 92563 3,~0-SJ) Suri sitle, I SoLj IMPORTANT: Please complete Project and Sample Identification Data as you would like it to appear in report & include this form with samples. Company Name: GeoTek, Inc. Contact Name: Chris Livesey Phone No: 949-338-9233 Mailing Address: 1384 Poinsettia Ave, Suite A Contact Email: clivesey@geotekusa.com Accounting Contact: Lesley White Invoice Email: Client Project No: 3630-SD Project Name: Surfside Lane 3-5 Day 3 Day 24Hr P.0.11: Guanntf.f RUSH ANALYSIS REQUESTED (Please circle) Srandard 50o/.mo.rk-up l ®"mark•up (Business Days) Turn Around Time: w ri H f; ~~ t 36 36 36 ;;6 0.. 'E ~] ·: ~::g 0 0 0 -~ 8 en " !i:lll !c:i: ~~ "' M 0: ~ Results By: D Phone D Fax D Email :i;o "z ~~ ~~ F (I)~ rA~ ~~ • "' :3' < I-~ El-o < ~ 2 § &l "' .. ·en o 2-13-Default ~:;; ij~ ~E ~E ~8 ~E ~E a, ~ E eE ~E ~E ~~ ~E g g-th ~:: "' Date & Received by : z..ow "' -~1:1 ~a ~~ n ~~ ~1:1 ~1:1 ~ ~ ~1:1 ;:: Pi:: "'~ ~~ Method <0 <o <o <o <o ~ * <O S{!eclul lrutmctlom1: Full Corrosion Serrics Reports "' :.'.l "' ·;;; ·;;; >, G•oQuad ·i:: .; ., 0 >, en t:: 0 i5 ·;:;: .; ~ C 0 8. C " .; 0 :~ 2 0 ·.:: < " .; "' .£ "' " " <I> ·a ·~ ·-" C :§ -0 " -~ Pi:: :g t:: ·;;; .; -0 i5 -~ C ~ 0 0 ..9 ..9 ] B -~ t:: "' C t:: 0 u .; " <> " :;; "' B § g .g Pi:: ]> ., ~ 0 C 0 0 0. ., -"' -~ ·;;; " 0.. ·a " "' § 0 u u" < .; ::, :r: ., B -0 " " 0 ~ -0 ..c § l ·;;; :.'.l ~ 0 "' .... ~ ~ ~ 0 ·i:: ul Pi:: ·i:: -0 '§ 5l' u::, 0 .... ~ 0 0 ti:: 1 il g §, ·o & :-:::i~ ~ :s ] ] 00 .,. ~ ~ DATE -0 0 u 0 ., fil 0 SAMPLE ID -BORE # DESCRIPTION DEPTH(lt) ·o :r: "3 :a " "3 _g ..c 0 0 "' .; 0 > 0 ..c " ::, COLLECl'ED en 0. Cl) u Pi:: en z ii. 0.. ;J en 0.. ::E u iii en '1.l i3: ::E ::E t-t-::E ....l 0.. X ;3: I 8-1, 88-1 Light Brown SAND 5-10' 2/17/20 X 2 3 8: 4 5 6 7 8 9 10 II 12 13 14 RF 15 II APPENDIX C GENERAL EARTHWORK GRADING GUIDELINES GENERAL GRADING GUIDELINES Guidelines presented herein are intended to address general construction procedures for earthwork construction. Specific situations and conditions often arise which cannot reasonably be discussed in general guidelines, when anticipated these are discussed in the text of the report. Often unanticipated conditions are encountered which may necessitate modification or changes to these guidelines. It is our hope that these will assist the contractor to more efficiently complete the project by providing a reasonable understanding of the procedures that would be expected during earthwork and the testing and observation used to evaluate those procedures. General Grading should be performed to at least the minimum requirements of governing agencies, Chapters 18 and 33 of the Uniform Building Code and the guidelines presented below. Preconstruction Meeting A preconstruction meeting should be held prior to site earthwork. Any questions the contractor has regarding our recommendations, general site conditions, apparent discrepancies between reported and actual conditions and/or differences in procedures the contractor intends to use should be brought up at that meeting. The contractor (including the main onsite representative) should review our report and these guidelines in advance of the meeting. Any comments the contractor may have regarding these guidelines should be brought up at that meeting. Grading Observation and Testing 1. Observation of the fill placement should be provided by our representative during grading. Verbal communication during the course of each day will be used to inform the contractor of test results. The Contractor should receive a copy of the "Daily Field Report" indicating results of field density tests that day. If our representative does not provide the contractor with these reports, our office should be notified. 2. Testing and observation procedures are, by their nature, specific to the work or area observed and location of the tests taken, variability may occur in other locations. The contractor is responsible for the uniformity of the grading operations, our observations and test results are intended to evaluate the contractor’s overall level of efforts during grading. The contractor’s personnel are the only individuals participating in all aspect of site work. Compaction testing and observation should not be considered as relieving the contractor’s responsibility to properly compact the fill. 3. Cleanouts, processed ground to receive fill, key excavations, and subdrains should be observed by our representative prior to placing any fill. It will be the Contractor's responsibility to notify our representative or office when such areas are ready for observation. 4. Density tests may be made on the surface material to receive fill, as considered warranted by this firm. 5. In general, density tests would be made at maximum intervals of two feet of fill height or every 1,000 cubic yards of fill placed. Criteria will vary depending on soil conditions and size of the fill. More frequent testing may be performed. In any case, an adequate number of field density tests should be made to evaluate the required compaction and moisture content is generally being obtained. 6. Laboratory testing to support field test procedures will be performed, as considered warranted, based on conditions encountered (e.g. change of material sources, types, etc.) Every effort will be Grading Guidelines ` APPENDIX C Page 1 made to process samples in the laboratory as quickly as possible and in progress construction projects are our first priority. However, laboratory workloads may cause in delays and some soils may require a minimum of 48 to 72 hours to complete test procedures. Whenever possible, our representative(s) should be informed in advance of operational changes that might result in different source areas for materials. 7. Procedures for testing of fill slopes are as follows: a) Density tests should be taken periodically during grading on the flat surface of the fill three to five feet horizontally from the face of the slope. b) If a method other than over building and cutting back to the compacted core is to be employed, slope compaction testing during construction should include testing the outer six inches to three feet in the slope face to determine if the required compaction is being achieved. 8. Finish grade testing of slopes and pad surfaces should be performed after construction is complete. Site Clearing 1. All vegetation, and other deleterious materials, should be removed from the site. If material is not immediately removed from the site it should be stockpiled in a designated area(s) well outside of all current work areas and delineated with flagging or other means. Site clearing should be performed in advance of any grading in a specific area. 2. Efforts should be made by the contractor to remove all organic or other deleterious material from the fill, as even the most diligent efforts may result in the incorporation of some materials. This is especially important when grading is occurring near the natural grade. All equipment operators should be aware of these efforts. Laborers may be required as root pickers. 3. Nonorganic debris or concrete may be placed in deeper fill areas provided the procedures used are observed and found acceptable by our representative. Typical procedures are similar to those indicated on Plate G-4. Treatment of Existing Ground 1. Following site clearing, all surficial deposits of alluvium and colluvium as well as weathered or creep effected bedrock, should be removed (see Plates G-1, G-2 and G-3) unless otherwise specifically indicated in the text of this report. 2. In some cases, removal may be recommended to a specified depth (e.g. flat sites where partial alluvial removals may be sufficient) the contractor should not exceed these depths unless directed otherwise by our representative. 3. Groundwater existing in alluvial areas may make excavation difficult. Deeper removals than indicated in the text of the report may be necessary due to saturation during winter months. 4. Subsequent to removals, the natural ground should be processed to a depth of six inches, moistened to near optimum moisture conditions and compacted to fill standards. 5. Exploratory back hoe or dozer trenches still remaining after site removal should be excavated and filled with compacted fill if they can be located. Subdrainage 1. Subdrainage systems should be provided in canyon bottoms prior to placing fill, and behind buttress and stabilization fills and in other areas indicated in the report. Subdrains should conform to schematic diagrams G-1 and G-5, and be acceptable to our representative. Grading Guidelines ` APPENDIX C Page 2 GEOTEK 2. For canyon subdrains, runs less than 500 feet may use six-inch pipe. Typically, runs in excess of 500 feet should have the lower end as eight-inch minimum. 3. Filter material should be clean, 1/2 to 1-inch gravel wrapped in a suitable filter fabric. Class 2 permeable filter material per California Department of Transportation Standards tested by this office to verify its suitability, may be used without filter fabric. A sample of the material should be provided to the Soils Engineer by the contractor at least two working days before it is delivered to the site. The filter should be clean with a wide range of sizes. 4. Approximate delineation of anticipated subdrain locations may be offered at 40-scale plan review stage. During grading, this office would evaluate the necessity of placing additional drains. 5. All subdrainage systems should be observed by our representative during construction and prior to covering with compacted fill. 6. Subdrains should outlet into storm drains where possible. Outlets should be located and protected. The need for backflow preventers should be assessed during construction. 7. Consideration should be given to having subdrains located by the project surveyors. Fill Placement 1. Unless otherwise indicated, all site soil and bedrock may be reused for compacted fill; however, some special processing or handling may be required (see text of report). 2. Material used in the compacting process should be evenly spread, moisture conditioned, processed, and compacted in thin lifts six (6) to eight (8) inches in compacted thickness to obtain a uniformly dense layer. The fill should be placed and compacted on a nearly horizontal plane, unless otherwise found acceptable by our representative. 3. If the moisture content or relative density varies from that recommended by this firm , the Contractor should rework the fill until it is in accordance with the following: a) Moisture content of the fill should be at or above optimum moisture. Moisture should be evenly distributed without wet and dry pockets. Pre-watering of cut or removal areas should be considered in addition to watering during fill placement, particularly in clay or dry surficial soils. The ability of the contractor to obtain the proper moisture content will control production rates. b) Each six-inch layer should be compacted to at least 90 percent of the maximum dry density in compliance with the testing method specified by the controlling governmental agency. In most cases, the testing method is ASTM Test Designation D-1557. 4. Rock fragments less than eight inches in diameter may be utilized in the fill, provided: a) They are not placed in concentrated pockets; b) There is a sufficient percentage of fine-grained material to surround the rocks; c) The distribution of the rocks is observed by and acceptable to our representative. 5. Rocks exceeding eight (8) inches in diameter should be taken off site, broken into smaller fragments, or placed in accordance with recommendations of this firm in areas designated suitable for rock disposal (See Plate G-4). On projects where significant large quantities of oversized materials are anticipated, alternate guidelines for placement may be included. If significant oversize materials are encountered during construction, these guidelines should be requested. 6. In clay soil dry or large chunks or blocks are common; if in excess of eight (8) inches minimum dimension then they are considered as oversized. Sheepsfoot compactors or other suitable methods should be used to break up blocks. When dry they should be moisture conditioned to provide a uniform condition with the surrounding fill. Grading Guidelines ` APPENDIX C Page 3 GEOTEK Slope Construction 1. The Contractor should obtain a minimum relative compaction of 90 percent out to the finished slope face of fill slopes. 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. 2. Slopes trimmed to the compacted core should be overbuilt by at least three (3) feet with compaction efforts out to the edge of the false slope. Failure to properly compact the outer edge results in trimming not exposing the compacted core and additional compaction after trimming may be necessary. 3. If fill slopes are built "at grade" using direct compaction methods then the slope construction should be performed so that a constant gradient is maintained throughout construction. Soil should not be "spilled" over the slope face nor should slopes be "pushed out" to obtain grades. Compaction equipment should compact each lift along the immediate top of slope. Slopes should be back rolled or otherwise compacted at approximately every 4 feet vertically as the slope is built. 4. Corners and bends in slopes should have special attention during construction as these are the most difficult areas to obtain proper compaction. 5. Cut slopes should be cut to the finished surface, excessive undercutting and smoothing of the face with fill may necessitate stabilization. Keyways, Buttress and Stabilization Fills Keyways are needed to provide support for fill slope and various corrective procedures. 1. Side-hill fills should have an equipment-width key at their toe excavated through all surficial soil and into competent material and tilted back into the hill (Plates G-2, G-3). As the fill is elevated, it should be benched through surficial soil and slopewash, and into competent bedrock or other material deemed suitable by our representatives (See Plates G-1, G-2, and G-3). 2. Fill over cut slopes should be constructed in the following manner: a) All surficial soils and weathered rock materials should be removed at the cut-fill interface. b) A key at least one (1) equipment width wide (or as needed for compaction) and tipped at least one (1) foot into slope should be excavated into competent materials and observed by our representative. c) The cut portion of the slope should be excavated prior to fill placement to evaluate if stabilization is necessary, the contractor should be responsible for any additional earthwork created by placing fill prior to cut excavation. (See Plate G-3 for schematic details.) 3. Daylight cut lots above descending natural slopes may require removal and replacement of the outer portion of the lot. A schematic diagram for this condition is presented on Plate G-2. 4. A basal key is needed for fill slopes extending over natural slopes. A schematic diagram for this condition is presented on Plate G-2. 5. All fill slopes should be provided with a key unless within the body of a larger overall fill mass. Please refer to Plate G-3, for specific guidelines. Anticipated buttress and stabilization fills are discussed in the text of the report. The need to stabilize other proposed cut slopes will be evaluated during construction. Plate G-5 is shows a schematic of buttress construction. Grading Guidelines ` APPENDIX C Page 4 GEOTEK 1. All backcuts should be excavated at gradients of 1:1 or flatter. The backcut configuration should be determined based on the design, exposed conditions and need to maintain a minimum fill width and provide working room for the equipment. 2. On longer slopes backcuts and keyways should be excavated in maximum 250 feet long segment. The specific configurations will be determined during construction. 3. All keys should be a minimum of two (2) feet deep at the toe and slope toward the heel at least one foot or two (2%) percent whichever is greater. 4. Subdrains are to be placed for all stabilization slopes exceeding 10 feet in height. Lower slopes are subject to review. Drains may be required. Guidelines for subdrains are presented on Plate G-5. 5. Benching of backcuts during fill placement is required. Lot Capping 1. When practical, the upper three (3) feet of material placed below finish grade should be comprised of the least expansive material available. Preferably, highly and very highly expansive materials should not be used. We will attempt to offer advise based on visual evaluations of the materials during grading, but it must be realized that laboratory testing is needed to evaluate the expansive potential of soil. Minimally, this testing takes two (2) to four (4) days to complete. 2. Transition lots (cut and fill) both per plan and those created by remedial grading (e.g. lots above stabilization fills, along daylight lines, above natural slope, etc.) should be capped with a three foot thick compacted fill blanket. 3. Cut pads should be observed by our representative(s) to evaluate the need for overexcavation and replacement with fill. This may be necessary to reduce water infiltration into highly fractured bedrock or other permeable zones, and/or due to differing expansive potential of materials beneath a structure. The overexcavation should be at least three feet. Deeper overexcavation may be recommended in some cases. ROCK PLACEMENT AND ROCK FILL GUIDELINES It is anticipated that large quantities of oversize material would be generated during grading. It’s likely that such materials may require special handling for burial. Although alternatives may be developed in the field, the following methods of rock disposal are recommended on a preliminary basis. Limited Larger Rock When materials encountered are principally soil with limited quantities of larger rock fragments or boulders, placement in windrows is recommended. The following procedures should be applied: 1. Oversize rock (greater than 8 inch) should be placed in windrows. a) Windrows are rows of single file rocks placed to avoid nesting or clusters of rock. b) Each adjacent rock should be approximately the same size (within ~one foot in diameter). c) The maximum rock size allowed in windrows is four feet 2. A minimum vertical distance of three feet between lifts should be maintained. Also, the windrows should be offset from lift to lift. Rock windrows should not be closer than 15 feet to the face of fill slopes and sufficient space must be maintained for proper slope construction (see Plate G-4). 3. Rocks greater than eight inches in diameter should not be placed within seven feet of the finished subgrade for a roadway or pads and should be held below the depth of the lowest utility. This will allow easier trenching for utility lines. Grading Guidelines ` APPENDIX C Page 5 4. Rocks greater than four feet in diameter should be broken down, if possible, or they may be placed in a dozer trench. Each trench should be excavated into the compacted fill a minimum of one foot deeper than the largest diameter of rock. a) The rock should be placed in the trench and granular fill materials (SE>30) should be flooded into the trench to fill voids around the rock. b) The over size rock trenches should be no closer together than 15 feet from any slope face. c) Trenches at higher elevation should be staggered and there should be a minimum of four feet of compacted fill between the top of the one trench and the bottom of the next higher trench. d) It would be necessary to verify 90 percent relative compaction in these pits. A 24 to 72 hour delay to allow for water dissipation should be anticipated prior to additional fill placement. Structural Rock Fills If the materials generated for placement in structural fills contains a significant percentage of material more than six (6) inch in one dimension, then placement using conventional soil fill methods with isolated windrows would not be feasible. In such cases the following could be considered. 1. Mixes of large of rock or boulders may be placed as rock fill. They should be below the depth of all utilities both on pads and in roadways and below any proposed swimming pools or other excavations. If these fills are placed within seven (7) feet of finished grade they may effect foundation design. 2. Rock fills are required to be placed in horizontal layers that should not exceed two feet in thickness, or the maximum rock size present, which ever is less. All rocks exceeding two feet should be broken down to a smaller size, windrowed (see above), or disposed of in non-structural fill areas. Localized larger rock up to 3 feet in largest dimension may be placed in rock fill as follows: a) individual rocks are placed in a given lift so as to be roughly 50% exposed above the typical surface of the fill , b) loaded rock trucks or alternate compactors are worked around the rock on all sides to the satisfaction of the soil engineer, c) the portion of the rock above grade is covered with a second lift. 3. Material placed in each lift should be well graded. No unfilled spaces (voids) should be permitted in the rock fill. Compaction procedures: Compaction of rock fills is largely procedural. The following procedures have been found to generally produce satisfactory compaction. 1. Provisions for routing of construction traffic over the fill should be implemented. a) Placement should be by rock trucks crossing the lift being placed and dumping at its edge. b) The trucks should be routed so that each pass across the fill is via a different path and that all areas are uniformly traversed. c) The dumped piles should be knocked down and spread by a large dozer (D-8 or larger suggested). (Water should be applied before and during spreading.) 2. Rock fill should be generously watered (sluiced) a) Water should be applied by water trucks to the: i) dump piles, Grading Guidelines ` APPENDIX C Page 6 ii) front face of the lift being placed and, iii) surface of the fill prior to compaction. b) No material should be placed without adequate water. c) The number of water trucks and water supply should be sufficient to provide constant water. d) Rock fill placement should be suspended when water trucks are unavailable: i) for more than 5 minutes straight, or, ii) for more than 10 minutes/hour. 3. In addition to the truck pattern and at the discretion of the soil engineer, large, rubber tired compactors may be required. a) The need for this equipment will depend largely on the ability of the operators to provide complete and uniform coverage by wheel rolling with the trucks. b) Other large compactors will also be considered by the soil engineer provided that required compaction is achieved. 4. Placement and compaction of the rock fill is largely procedural. Observation by trenching should be made to check: a) the general segregation of rock size, b) for any unfilled spaces between the large blocks, and c) the matrix compaction and moisture content. 5. Test fills may be required to evaluate relative compaction of finer grained zones or as deemed appropriate by the soil engineer. a) A lift should be constructed by the methods proposed as proposed 6. Frequency of the test trenching is to be at the discretion of the soil engineer. Control areas may be used to evaluate the contractors procedures. 7. A minimum horizontal distance of 15 feet should be maintained from the face of the rock fill and any finish slope face. At least the outer 15 feet should be built of conventional fill materials. Piping Potential and Filter Blankets: Where conventional fill is placed over rock fill, the potential for piping (migration) of the fine grained material from the conventional fill into rock fills will need to be addressed. The potential for particle migration is related to the grain size comparisons of the materials present and in contact with each other. Provided that 15 percent of the finer soil is larger than the effective pore size of the coarse soil, then particle migration is substantially mitigated. This can be accomplished with a well- graded matrix material for the rock fill and a zone of fill similar to the matrix above it. The specific gradation of the fill materials placed during grading must be known to evaluate the need for any type of filter that may be necessary to cap the rock fills. This, unfortunately, can only be accurately determined during construction. In the event that poorly graded matrix is used in the rock fills, properly graded filter blankets 2 to 3 feet thick separating rock fills and conventional fill may be needed. As an alternative, use of two layers of filter fabric (Mirafi 700 x or equivalent) could be employed on top of the rock fill. In order to mitigate excess puncturing, the surface of the rock fill should be well broken down and smoothed prior to placing the filter fabric. The first layer of the fabric may then be placed and covered with relatively permeable fill material (with respect to overlying material) 1 to 2 feet thick. The relative permeable material should be compacted to fill standards. The second layer of fabric should be placed and conventional fill placement continued. Grading Guidelines ` APPENDIX C Page 7 Subdrainage Rock fill areas should be tied to a subdrainage system. If conventional fill is placed that separates the rock from the main canyon subdrain then a secondary system should be installed. A system consisting of an adequately graded base (3 to 4 percent to the lower side) with a collector system and outlets may suffice. Additionally, at approximately every 25 foot vertical interval, a collector system with outlets should be placed at the interface of the rock fill and the conventional fill blanketing a fill slope Monitoring Depending upon the depth of the rock fill and other factors, monitoring for settlement of the fill areas may be needed following completion of grading. Typically, if rock fill depths exceed 40 feet, monitoring would be recommend prior to construction of any settlement sensitive improvements. Delays of 3 to 6 months or longer can be expected prior to the start of construction. UTILITY TRENCH CONSTRUCTION AND BACKFILL Utility trench excavation and backfill is the contractors responsibility. The geotechnical consultant typically provides periodic observation and testing of these operations. While, efforts are made to make sufficient observations and tests to verify that the contractors’ methods and procedures are adequate to achieve proper compaction, it is typically impractical to observe all backfill procedures. As such, it is critical that the contractor use consistent backfill procedures. Compaction methods vary for trench compaction and experience indicates many methods can be successful. However, procedures that “worked” on previous projects may or may not prove effective on a given site. The contractor(s) should outline the procedures proposed, so that we may discuss them prior to construction. We will offer comments based on our knowledge of site conditions and experience. 1. Utility trench backfill in slopes, structural areas, in streets and beneath flat work or hardscape should be brought to at least optimum moisture and compacted to at least 90 percent of the laboratory standard. Soil should be moisture conditioned prior to placing the trench. 2. Flooding and jetting are not typically recommended or acceptable for native soils. Flooding or jetting may be used with select sand having a Sand Equivalent (SE) of 30 or higher. This is typically limited to the following uses: a) shallow (12 + inches) under slab interior trenches and, b) as bedding in pipe zone. The water should be allowed to dissipate prior to pouring slabs or completing trench compaction. 3. Care should be taken not to place soils at high moisture content within the upper three feet of the trench backfill in street areas, as overly wet soils may impact subgrade preparation. Moisture may be reduced to 2% below optimum moisture in areas to be paved within the upper three feet below sub grade. 4. Sand backfill should not be allowed in exterior trenches adjacent to and within an area extending below a 1:1 projection from the outside bottom edge of a footing, unless it is similar to the surrounding soil. 5. Trench compaction testing is generally at the discretion of the geotechnical consultant. Testing frequency will be based on trench depth and the contractors procedures. A probing rod would be used to assess the consistency of compaction between tested areas and untested areas. If zones are found that are considered less compact than other areas, this would be brought to the contractors attention. Grading Guidelines ` APPENDIX C Page 8 JOB SAFETY General Personnel safety is a primary concern on all job sites. The following summaries our safety considerations for use by all our employees on multi-employer construction sites. On ground personnel are at highest risk of injury and possible fatality on grading construction projects. The company recognizes that construction activities will vary on each site and that job site safety is the contractor's responsibility. However, it is, imperative that all personnel be safety conscious to avoid accidents and potential injury. In an effort to minimize risks associated with geotechnical testing and observation, the following precautions are to be implemented for the safety of our field personnel on grading and construction projects. 1. Safety Meetings: Our field personnel are directed to attend the contractor's regularly scheduled safety meetings. 2. Safety Vests: Safety vests are provided for and are to be worn by our personnel while on the job site. 3. Safety Flags: Safety flags are provided to our field technicians; one is to be affixed to the vehicle when on site, the other is to be placed atop the spoil pile on all test pits. In the event that the contractor's representative observes any of our personnel not following the above, we request that it be brought to the attention of our office. Test Pits Location, Orientation and Clearance The technician is responsible for selecting test pit locations. The primary concern is the technician's safety. However, it is necessary to take sufficient tests at various locations to obtain a representative sampling of the fill. As such, efforts will be made to coordinate locations with the grading contractors authorized representatives (e.g. dump man, operator, supervisor, grade checker, etc.), and to select locations following or behind the established traffic pattern, preferable outside of current traffic. The contractors authorized representative should direct excavation of the pit and safety during the test period. Again, safety is the paramount concern. Test pits should be excavated so that the spoil pile is placed away from oncoming traffic. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates that the fill be maintained in a drivable condition. Alternatively, the contractor may opt to park a piece of equipment in front of test pits, particularly in small fill areas or those with limited access. A zone of non-encroachment should be established for all test pits (see diagram below) No grading equipment should enter this zone during the test procedure. The zone should extend outward to the sides approximately 50 feet from the center of the test pit and 100 feet in the direction of traffic flow. This zone is established both for safety and to avoid excessive ground vibration, which typically decreases test results. Grading Guidelines ` APPENDIX C Page 9 50 ft Zone of Non-Encroachment 50 ft Zone of Non-Encroachment Traffic Direction Vehicle parked here Test Pit Spoil pile Spoil pile Test Pit SIDE VIEW PLAN VIEW TEST PIT SAFETY PLAN 10 0 ft Zone of Non-Encroachment Slope Tests When taking slope tests, the technician should park their vehicle directly above or below the test location on the slope. The contractor's representative should effectively keep all equipment at a safe operation distance (e.g. 50 feet) away from the slope during testing. The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter of the fill in a highly visible location. Trench Safety: It is the contractor's responsibility to provide safe access into trenches where compaction testing is needed. Trenches for all utilities should be excavated in accordance with CAL-OSHA and any other applicable safety standards. Safe conditions will be required to enable compaction testing of the trench backfill. All utility trench excavations in excess of 5 feet deep, which a person enters, are to be shored or laid back. Trench access should be provided in accordance with OSHA standards. Our personnel are directed not to enter any trench by being lowered or "riding down" on the equipment. Our personnel are directed not to enter any excavation which; 1. is 5 feet or deeper unless shored or laid back, 2. exit points or ladders are not provide, 3. displays any evidence of instability, has any loose rock or other debris which could fall into the trench, or 4. displays any other evidence of any unsafe conditions regardless of depth. If the contractor fails to provide safe access to trenches for compaction testing, our company policy requires that the soil technician withdraws and notifies their supervisor. The contractors representative will then be contacted in an effort to effect a solution. All backfill not tested due to safety concerns or other reasons is subject to reprocessing and/or removal. Grading Guidelines ` APPENDIX C Page 10 Procedures In the event that the technician's safety is jeopardized or compromised as a result of the contractor's failure to comply with any of the above, the technician is directed to inform both the developer's and contractor's representatives. If the condition is not rectified, the technician is required, by company policy, to immediately withdraw and notify their supervisor. The contractor’s representative will then be contacted in an effort to effect a solution. No further testing will be performed until the situation is rectified. Any fill placed in the interim can be considered unacceptable and subject to reprocessing, recompaction or removal. In the event that the soil technician does not comply with the above or other established safety guidelines, we request that the contractor bring this to technicians attention and notify our project manager or office. Effective communication and coordination between the contractors' representative and the field technician(s) is strongly encouraged in order to implement the above safety program and safety in general. The safety procedures outlined above should be discussed at the contractor's safety meetings. This will serve to inform and remind equipment operators of these safety procedures particularly the zone of non- encroachment. The safety procedures outlined above should be discussed at the contractor's safety meetings. This will serve to inform and remind equipment operators of these safety procedures particularly the zone of non- encroachment. Grading Guidelines ` APPENDIX C Page 11 1384 Poinsettia Avenue, Suite A Vista, California 92083 TYPICAL CANYON CLEANOUT STANDARD GRADING GUIDELINES ALTERNATES Original Ground 3’ Loose Surface Materials PLATE G-1 Finish Grade 3’ Suitable Material Suitable Material 6” Perforated Pipe in 9 cubic feet per LinealFoot Clean Gravel Wrapped in Filter Fabric Construct Bencheswhere slope exceeds 5:1 Bottom of Cleanout to Be At Least 1.5 Times the Width of Compaction Equipment 4 feet typical Slope to Drain Original Ground Loose Surface Materials Finish Grade Suitable MaterialConstruct Bencheswhere slope exceeds 5:1 Bottom of Cleanout to Be AtLeast1.5 Times the Width ofCompaction Equipment 4 feet typical Slope to Drain 6” Perforated Pipe in 9 cubic feetper Lineal Foot Clean GravelWrapped in Filter Fabric TREATMENT ABOVE NATURAL SLOPES STANDARD GRADING GUIDELINES TYPICAL FILL SLOPE OVER NATURAL DESCENDING SLOPE Topsoil Bedrock PLATE G-2 Finish Grade Fill Slope Daylight Cut Line per Plan Project Removal at 1 to 1 Min. 3 FeetCompacted Fill Colluvium Creep Zone Minimum 15 Feet Wide or 1.5 EquipmentWidths for Compaction Toe of Fill Slope per Plan DAYLIGHT CUT AREA OVER NATURAL DESCENDING SLOPE Topsoil Structural SetbackWithout Corrective Work Project Removalat 1 to 1 Colluvium Creep Zone Min. 2 Feet Minimum 15 Feet Wideor 1.5 EquipmentWidths for Compaction Finish Grade Bedrock Min. 3 FeetCompacted Fill Min.2 Feet Compacted Fill Compacted Fill 1384 Poinsettia Avenue, Suite A Vista, California 92081-8505 Topsoil Colluvium Creep Zone COMMON FILL SLOPE KEYS STANDARD GRADING GUIDELINES TYPICAL FILL SLOPE OVER CUT SLOPE Topsoil Bedrock PLATE G-3 Finish Grade 2: 1 Fill Slope 4’ Typical Colluvium Creep Zone Minimum 15 Feet Wideor 1.5 EquipmentWidths for Compaction Toe of Fill Slope per Plan TYPICAL FILL SLOPE Bedrock or Suitable Dense Material Minimum compacted fill requiredto provide lateral support. Excavate key if width or depthless than indicated in table above Cut Slope SLOPEHEIGHT MIN. KEY WIDTH MIN. KEY DEPTH 5 10 15 20 25 >25 7 10 15 15 15 SEE TEXT 1 1.5 2 2.5 3 CONTRACTOR TO VERIFYWITH SOIL ENGINEERPRIOR TO CONSTRUCTION 1384 Poinsettia Avenue, Suite A Vista, California 92081-8505 NOTES: 1)SOIL FILL OVER WINDROW SHOULE BE 7 FEET OR PER JURISDUICTIONAL STANDARDS AND SUFFICIENTFOR FUTURE EXCAVATIONS TO AVOID ROCKS 2)MAXIMUM ROCK SIZE IN WINDROWS IS 4 FEET MINIMUM DIAMETER 3)SOIL AROUND WINDROWS TO BE SANDY MATERIAL SUBJECT TO SOIL ENGINEER ACCEPTANCE 4)SPACING AND CLEARANCES MUST BE SUFFICIENT TO ALLOW FOR PROPER COMPACTION 5)INDIVDUAL LARGE ROCKS MAY BE BURIED IN PITS. ROCK BURIAL DETAILS STANDARD GRADING GUIDELINES PLATE G-4 SEE NOTE 1 15’ MIN.3’ MIN. 3’ MIN. MINIMUM 15’ CLEAR OR 1.5 EQUIPMENT WIDTHS FOR COMPACTION STAGGER ROWS HORIZONTALLY NO ROCKS IN THIS ZONE CROSS SECTIONAL VIEW FINISH GRADE FILL SLOPE PLAN VIEW FILL SLOPE MINIMUM 15’ CLEAR OR 1.5 EQUIPMENTWIDTHS FOR COMPACTION MINIMUM 15’ CLEAR OR 1.5 EQUIPMENT WIDTHS FOR COMPACTION PLACE ROCKS END TO END DO NOT PILE OR STACK ROCKS SOIL TO BE PLACE AROUND AND OVER ROCKS THEN FLOODED INTOVOIDS. MUST COMPACT AROUND AND OVER EACH ROCK WINDROW 1384 Poinsettia Avenue, Suite A Vista, California 92081-8505 6” Perforated Pipe in 6 cubic feet per lineal foot clean gravel wrapped in filter fabric outlet pipe to gravity flow BEDROCK COMPACTED FILL MIN. 3 FEETCOMPACTED FILL TERRACE DRAIN AS REQUIRED 2 1 MIN. 15 FEET WIDE OR 1.5 EQUIPMENT WIDTHS FOR COMPACTION MIN. 2 FEET EMBEDDMENT 1384 Poinsettia Avenue, Suite A Vista, California 92083 Typical Buttress and Stabilization Fill PLATE G-5 4” or 6” Perforated Pipe in 6 cubicfeet per lineal foot clean gravelwrapped in filter fabric outlet pipeto gravity flow at 2% min. TRANSITION & UNDERCUT LOTS PLATE G-6 TRANSITION LOT PROPSED FINISH GRADE COMPETENT MATERIAL 4’ MIN. OVEREXCAVATE ANDRECOMPACT PROPOSED STRUCTURE COMPACTED FILL 3 1 OVEREXCAVATION AND BENCHING NOTTO EXCEED INCLINATION OF 3:1 (H:V) UNDERCUT LOT PROPSED FINISH GRADE PROPOSED STRUCTURE 4’ MIN. COMPETENT MATERIAL COMPACTED FILL OVEREXCAVATE ANDRECOMPACTOVEREXCAVATION TO HAVE 1%FALL TOWARD FRONT OF LOT Notes:1.Removed/overexcavated soils should be recompacted in accordance with recommendations included in the text of the report.2.Location of cut/fill transition should verified in the field during site grading. STANDARD GRADING GUIDELINES1384 Poinsettia Avenue, Suite A Vista, California 92081-8505