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Home My WebLink AboutCDP 2019-0023; HERNANDEZ RESIDENCE; PRELIMINARY GEOTECHNICAL EVALUATION; 2019-10-18--------.--~ ------.. .. .. ... .. ! .. ... ... ,. I... ,. .. .. ... .. .. -... .. ' II .. 1111 .. .. .. .. .. ~ .. .. .. .. .. .. PROJECT No. 3592-SD .. .. .. - PRELIMINARY GEOTECHNICAL Evaluation FOR PROPOSED RESIDENTIAL DEVELOPMENT 36 77 Garfield Street CARLSBAD, CALIFORNIA PREPARED FOR Chris and Ramon Hernandez 38 Pine Avenue San Carlos, California 94070 PREPARED BY GEOTEK, INC. 1384 POINSETTIA AVENUE, SUITE A VISTA, CALIFORNIA 92081 GEOTEK FEB 11 202~ RECORD Cf Pt ct=:f ~µ; ;if Initial Date OCTOBER 18, 2019 .. ---.. .... ... ... -.. .. ... .. .. .. -.. .. --.. .. ... -.. .. .. -.. --.. ... - GeoTek, Inc. 1384 Poinsettia Avenue, Suite A Vista, CA 92081-8505 (760) 599-0509 (760) 599-0593 www.geotekusa.com Chris and Ramon Hernandez 3677 Garfield Street Carlsbad, California Attention: Subject: Chris Hernandez Preliminary Geotechnical Evaluation 3677 Garfield Street Carlsbad, California Dear Mrs. Hernandez: October 18, 20 19 Project No. 3592-SD We are pleased to provide herein the results of our preliminary geotechnical evaluation for the subject project located in the City of Carlsbad, California. This report presents the results of our limited evaluation and provides preliminary geotechnical recommendations for earthwork, foundation 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 submitte GeoTek, Inc . 11/ Chris"her D. Lives GEO 9584, Exp. 05/30/ Project Geologist ~ Timot Principal Geologist 1142 ~-R. Greni C 83 71, Exp. 09/30/21 · ect Engineer Distribution: (I) Addressee via email GEOTECHNICAL I ENVIRONMENTAL I MATERIALS ,. -... ... ... --.. --... ... -.. .. .. -.. ---.. ---.. -----.. - HERNANDEZRE~DENCE Preliminary Geotechnical Evaluation 3677 Garfield Street. Carlsbad. California TABLE OF CONTENTS Project No. 3592-SD October 18, 2019 Paee i I. PURPOSE AND SCOPE OF SERVICES ...................................................................................................... I 2. SITE DESCRIPTION AND PROPOSED DEVELOPMENT .................................................................... 1 2.1 Site Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 2.2 Proposed Development .......................................................................................................................... 2 3. FIELD EXPLORATION AND LABORATORY TESTING ...................................................................... 2 3.1 Field Exploration .................................................................................................................................... 2 3.2 Percolation Testing ............................................................................................................................... 2 3.3 Laboratory Testing ................................................................................................................................. 3 4. GEOLOGIC AND SOILS CONDITIONS .................................................................................................... 4 4.1 Regional Setting ..................................................................................................................................... 4 4.2 EARTH MATERIALS .............................................................................................................................. 4 4.2. I Undocumented Fill ................................................................................................................................. 4 4.2.2 Old Paralic Deposits ............................................................................................................................... 4 4.3 SURFACE WATER AND GROUNDWATER. ............................................................................................ 5 4.3. I Surface Water ....................................................................................................................................... 5 4.3.2 Groundwater ......................................................................................................................................... 5 4.4 EARTHQUAKE HAZARDS ..................................................................................................................... 5 4.4. I Surface Fault Rupture ............................................................................................................................ 5 4.4.2 Uquefaction/Seismic Settlement. ............................................................................................................. 5 4.4.3 Other Seismic Hazards .......................................................................................................................... 6 5. CONCLUSIONS AND RECOMMENDATIONS ....................................................................................... 6 5.1 General ................................................................................................................................................. 6 5.2 EARTHWORK CONSIDERATIONS ........................................................................................................ 6 5.2./ General ................................................................................................................................................. 6 5.2.2 Site Clearing and Preparation ................................................................................................................. 7 5.2.3 Remedial Grading .................................................................................................................................. 7 5.2.4 Engineered Fill ....................................................................................................................................... 8 5.2.5 Excavation Characteristics ...................................................................................................................... 8 5.2.6 Shrinkage and Bulking ........................................................................................................................... 8 5.2.7 Trench Excavations and Backfill ............................................................................................................. 8 5.3 DESIGN RECOMMENDATIONS ............................................................................................................ 9 5.3. I Stormwater lnf,ltration ........................................................................................................................... 9 5.3.2 Foundation Design Criteria ..................................................................................................................... 9 5.3.3 Underslab Moisture Membrane ............................................................................................................ 11 5.3.4 Miscellaneous Foundation Recommendations ........................................................................................ 12 5.3.5 Foundation Set Backs ........................................................................................................................... 12 5.3.6 Seismic Design Parameters .................................................................................................................. 13 5.3. 7 Soil Sulfate Content ............................................................................................................................. 13 5.4 RETAINING WALL DESIGN AND CONSTRUCT/ON ............................................................................. 14 5.4. I General Design Criteria ........................................................................................................................ 14 5.4.2 Wall Backfill and Drainage .................................................................................................................. 15 5.4.3 Restrained Retaining Walls .................................................................................................................. 15 5.5 POST CONSTRUCTION CONSIDERATIONS ........................................................................................ 16 5.5. I Landscape Maintenance and Planting ................................................................................................... 16 5.5.2 Drainage ............................................................................................................................................. 16 GEOTEK -- ... ,.. ... ,. ... .. ---.. .. ---- ,. ... ,.. ,.. ... .. -.. -.. - HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California TABLE OF CONTENTS Project No. 3592-SD October 18, 20 19 Paee ii 5.6 PLAN REVIEW AND CONSTRUCTION OBSERVATIONS ...................................................................... 17 6. LIMITATIONS ................................................................................................................................................. 17 7. SELECTED REFERENCES ............................................................................................................................ 19 ENCLOSURES Fi~ure I -Site Location Map Fiiure 2 -Boring Location Map Appendix A -Exploratory Hand Auger Logs and Infiltration Worksheets Appendix B -Results of Laboratory Testing Appendix C -General Earthwork Grading Guidelines GEOTEK ---.. .. .. .. -.. .. .. ---,. .. ... -,.. .. -.. ... .. -.. Ill ... --- 111■1 HERNANDEZ RESIDENCE Project No. 3592-SD October 18, 20 19 Pa&e I Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California I. 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 four (4) exploratory hand auger borings onsite and collection of bulk soil samples for subsequent laboratory testing. One hand auger boring was excavated as a percolation test. Laboratory testing of the soil samples collected during the field investigation. Review and evaluation of site seismicity, and 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 3677 Garfield Street in the City of Carlsbad, California (see Figure I). The site is generally bounded to the northeast by Garfield Drive, and to the southwest, southeast, and northwest by existing residences. The site is located in a relatively flat topographic setting with overall area drainage toward the ocean (southwest). Current improvements include a single-story residence and detached garage. Site surface conditions generally consisted of landscape and pavement improvements. Based on available aerial photographs the site was developed between the late 1930s to mid 1940s. Access is via a driveway off Garfield Street. Total relief across the site is on the order of a few feet, with localized surface drainage directed towards the ocean . GEOTEK -.. --.. .. ... -... ... ... ... --... -.. .. -... ... .. - 111111 -.. .. .. .. - HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California 2.2 Proposed Development Project No. 3592-SD October 18, 20 19 Paee 2 Based on review of the conceptual site plan prepared by Chereskin Architecture, dated August 14, 2019, proposed development will include a two-story main house constructed with stem walls and a raised floor, a detached garage with slab-on-grade, pavements, and landscaping . Access to the site will continue to be provided by a driveway off Garfield Street, however the new driveway will be along the south property line. The plan reviewed depicts site grades will be relatively unchanged. Associated improvements are anticipated to consist of a water infiltration device, wet and dry utilities. A copy of the plan provided is used as the base for the Boring Location 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 LABORATORYTESTING 3.1 Field Exploration Our initial field exploration was conducted on August 21, 2019 with a supplemental exploration program performed on October I , 2019 and consisted of a site reconnaissance, excavation of four hand auger borings, collection of bulk soil samples for subsequent laboratory testing, and a field percolation test. A Professional Engineer from our firm visually logged the borings and collected soil samples for laboratory analysis. Approximate locations of exploration locations are presented on the Boring Location Map, Figure 2. A description of material encountered in the borings is included in Appendix A. 3.2 Percolation Testing Boring P-1 was excavated as a percolation test hole. Following completion of the boring, percolation testing was performed by a representative from our firm in general conformance with the City of Carlsbad BMP Design Manual. The borehole was presoaked overnight and the testing was performed on the following day. Percolation testing was performed by adding potable water to the borings, recording the initial depth to water and allowing the water to percolate for IO minutes and the depth to water was measured. Water was generally added to each boring following each reading increment. In general, the percolation testing was GEOTEK HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California Project No. 3592-SD October 18, 20 19 Pa~e 3 performed for approximately 2 hours to allow rates to stabilize. Results of the final percolation increment were used to calculate an infiltration rate in inches per hour via the Porchet method. For design of shallow infiltration basins, converting percolation rates to infiltration rates via the Porchet method is generally acceptable and appropriate, as this method factors out the sidewall component of the percolation results and represents the bottom conditions of a shallow basin (infiltration). Therefore, the percolation data for boring P-1 was converted via the Porchet method. This method is consistent with the guidelines referenced in the City of Carlsbad BMP Design Manual. Results of our infiltration analysis without a factor of safety are presented in the follow table for the test area. Location Depth lnflitration Rate (inches) (inches per hour)* P-1 60 1.69 * Rate was converted to an infiltration rate via the Porchet method Copies of the infiltration conversion sheet are included in Appendix A. The material exposed along the boring sidewalls and at the bottom of P-1 was native soil. The test performed and reported are indicative of the respective soil type exposed, with the understanding that compaction during grading, whether intentional or unintentional, may change the infiltration rate. Over the lifetime of the storm water disposal areas, the percolation rates may be affected by silt build up and biological activities, as well as local variations in soil conditions. An appropriate factor of safety used to compute the design infiltration rate should be considered at the discretion of the design engineer and acceptance of the plan reviewer. 3.3 Laboratory Testing Laboratory testing was performed on bulk 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 C C C C C C C C C C C C C C C C HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street. Carlsbad. California Project No. 3592-SD October 18, 20 19 Paie 4 4. GEOLOGIC AND SOILS CONDITIONS 4.1 Regional Setting The subject property is located in the Peninsular Ranges geomorphic province. The Peninsular Ranges province is one of the largest geomorphic units in western North America. Basically, it extends roughly 975 miles from the north and northeasterly adjacent the Transverse Ranges geomorphic province to the tip of Baja California. This province varies in width from about 30 to I 00 miles. It is bounded on the west by the Pacific Ocean, on the south by the Gulf of California and on the east by the Colorado Desert Province. The Peninsular Ranges are essentially a series of northwest-southeast oriented fault blocks. Several major fault zones are found in this province. The Elsinore Fault zone and the San Jacinto Fault zones trend northwest-southeast and are found in the near the middle of the province. The San Andreas Fault zone borders the northeasterly margin of the province. The Newport-Inglewood-Rose Canyon Fault zone borders the southwest margin of the province. No faults are shown in the immediate site vicinity on the map reviewed for the area. 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 sporadic undocumented fill materials, colluvium, and soft sedimentary bedrock. 4.2.1 Undocumented Fill Undocumented fill soils were not locally observed but may be present below flatwork and existing structures. Other areas of undocumented fill (unmapped) are also likely present on the site. Undocumented fill soils are not considered suitable for support of structural site improvements, but may be re-used as engineered fill if properly placed. 4.2.2 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 topsoil. In the borings, old paralic deposits were encountered as poorly graded sand. Descriptions of the old paralic materials as encountered in our borings are shown on the boring logs included in Appendix A. GEOTEK I I • • • II C .. .. C C C C HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California 4.3 SURFACE WATER AND GROUNDWATER 4.3.1 Surface Water Project No. 3592-SD October 18, 2019 Pa~e 5 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. Overall site area drainage is in a southwesterly direction, toward the ocean. Provisions for surface drainage will need to be accounted for by the project civil engineer. 4.3.2 Groundwater Bases on a review of previous work performed in the area, groundwater is not anticipated to be within 15 of the ground surface at the subject site and 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 4.4.1 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-Prio/o" 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. 4.4.2 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. GEOTEK C C C JIii I.. C C C C C C C C C C HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street. Carlsbad. California Project No. 3592-SD October 18, 20 19 Pa&e 6 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. The liquefaction potential and seismic settlement potential on this site is considered negligible, due to nature of old paralic deposits in the area and absence of a shallow groundwater table. 4.4.3 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 the CalEMA Oceanside/San Luis Rey Tsunami Inundation Map. S. 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 5.2.1 General Earthwork and grading should be performed in accordance with the applicable grading ordinances of the City of Carlsbad, the 2016 (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. GEOTEK II • C C C C C C C C C C C C C C HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street. Carlsbad. California 5.2.2 Site Clearing and Preparation Project No. 3592-SD October 18, 20 19 Pa~e 7 Site preparation should start with demolition of the existing structures and 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. 5.2.3 Remedial Grading Prior to placement of fill materials, the upper loose and compressible materials should be removed for structural site areas that will be constructed as slab-on-grade. Removal depths in unmapped areas of existing undocumented fill and highly weathered paralic deposits are estimated to be up to approximately 3 feet. The lateral extent of removals beyond the outside edge of all settlement sensitive structures/foundations should be equivalent to that vertically removed. Depending on actual field conditions encountered during grading, locally deeper and/or shallower areas of removal may be necessary. At a minimum, the cut portion(s) of any slab-on-grade building pad areas in site formational or suitable material(s) should be overexcavated a minimum of three (3) feet below finish pad grade or a minimum of two (2) feet below the bottom of the deepest proposed footing, whichever is deeper. Overexcavations should extend a minimum of three (3) feet outside the proposed building envelope(s). Areas that will support pavements should be overexcavated a minimum of one (I) foot below the bottom of the pavement. Where possible, overexcavations should extend a minimum of two (2) feet outside the proposed pavement envelope(s). 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 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 Geo T ek representative prior to scarification. The 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. GEOTEK • .. C C C C C C C C C HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street. Carlsbad, California 5.2.4 Engineered Fill Project No. 3592-SD October I 8, 20 I 9 Pa&e 8 Onsite materials 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. The earthwork contractor should have the proposed excavated materials to be used as engineered fill at this project approved by the soils engineer prior to placement. 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 relative compaction of 90% as determined in accordance with laboratory test procedure ASTM D 1557. 5.2.5 Excavation Characteristics Excavations in the onsite undocumented fill and old paralic materials can generally be accomplished with heavy-duty earthmoving or excavating equipment in good operating condition. Less weathered bedrock materials are also likely to be encountered at depth and could locally require special techniques to excavate. 5.2.6 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. Shrinkage and bulking are largely dependent upon the degree of compactive effort achieved during construction. For planning purposes, a shrinkage factor ranging from 5 to 15 percent may be considered for the paralic and undocumented fill materials requiring removal and re- compaction. Subsidence should not be a factor on the subject site if removals are completed down to the recommended depths to expose bedrock materials. Site balance areas should be available in order to adjust project grades, depending on actual field conditions at the conclusion of site earthwork construction. 5.2. 7 Trench Excavations and Backfill Temporary excavations within the onsite materials should be stable at I: I inclinations for short durations during construction, and where cuts do not exceed IO feet in height. Temporary cuts to a maximum height of 4 feet can be excavated vertically. GEOTEK C C C C C C C C C C C C C C C C C HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street. Carlsbad, California Project No. 3592-SD October 18, 20 19 Pa&e 9 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. 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 material and backfill provided particles larger than 3± inches 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 5.3.1 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 a singular basin will be located at the rear of the lot, between the proposed garage and the existing block wall. Due to the proximity of existing and proposed foundations, we recommend that infiltration surfaces (bottom of basin, trench, or other device) be located at a minimum depth of 5 feet below ground surface. 5.3.2 Foundation Design Criteria Preliminary foundation design criteria, in general conformance with the 2016 CBC, are presented herein. Based on our investigation and understanding of the proposed construction, the following criteria are for slab-on-grade foundations bearing on engineered fill and for stem wall foundations bearing upon paralic deposits. These are typical design criteria and are not intended to supersede the design by the structural engineer. Based on our visual classification of materials encountered onsite and as verified by laboratory testing, soils near subgrade are "very low" expansive (El~20) per ASTM D4829. Additional GEOTEK HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California Project No. 3592-SD October 18, 20 19 Pa~e 10 laboratory testing should be performed at the completion of site grading to verify the expansion potential and plasticity index, if necessary, of the subgrade soils. The following criteria for design of foundations are preliminary. Additional laboratory testing of the samples obtained during grading should be performed and final recommendations should be based on as-graded soil conditions. MINIMUM DESIGN REQUIREMENTS FOR CONVENTIONALLY REINFORCED FOUNDATIONS DESIGN PARAMETER "Very Low" Expansion Potential (0<El<20) Foundation Embedment Depth or Minimum Perimeter One-Story -12 Beam Depth (inches below lowest adjacent finished Two-Story -18 grade) Three-Story -24 Supporting One Floor -12 Minimum Foundation Width (Inches)* Supporting Two Floors -15 Suooorting Three Floors -18 Minimum Slab Thickness (actual) 4inches Minimum Slab Reinforcing No. 3 rebar 24" on-center, each way, placed in the middle one-third of the slab thickness Minimum Footing Reinforcement Two No. 4 Reinforcing Bars, one (I) top and one (I) bottom Presaturation of Subgrade Soil for Slab-on-Grade Minimum I 00% to a depth of 12 inches (percent of optimum moisture content) *Code minimums per Table 1809.7 of the 2016 CBC should be complied with. 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 recommendations should be implemented into the design: • An allowable bearing capacity of 2000 pounds per square foot (psf) may be used for design of continuous and perimeter footings that meet the depth and width requirements in the table above. This value may be increased by 400 pounds per square foot for each additional 12 inches in depth and 200 pounds per square foot for each additional 12 inches in width to a maximum value of 3000 psf. Additionally, an increase of one-third may be applied when considering short-term live loads (e.g. seismic and wind loads). • Based on our experience in the area, structural foundations may be designed in accordance with 2016 CBC, and to withstand a total settlement of I inch and maximum differential settlement of one-half of the total settlement over a GEOTEK • • • .. -.. • .. ----.. ... .. --.. .. -... ... .. .. ---.. .. -- HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street. Carlsbad. California Project No. 3592-SD October 18, 2019 Pa&e I I horizontal distance of 40 feet. These values assume that seismic settlement potential is not a significant constraint. • 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 for footings founded on engineered fill. 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. • A grade beam, a minimum of 12 inches wide and 12 inches deep, should be utilized across large entrances, however, the base of the grade beam should be at the same elevation as the bottom of the adjoining footings . 5.3.3 Underslab Moisture Membrane 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 2016 California Green Building Standards Code (CALGreen) Section 4.505.2 and the 2016 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 I 0 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. GEOTEK • • • • .. ... .. ... -- ... ... ... ... ... ... ... .... ---,. .. .. • ---.. .. -.. .. .. HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street. Carlsbad, California Project No. 3592-SD October 18, 2019 Paie 12 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 . Geo T ek 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 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 . 5.3.4 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. 5.3.5 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: GEOTEK HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California Project No. 3592-SD October 18, 20 19 Pa~e 13 • The bottom of all footings for structures near retaining walls should be deepened so as to extend below a I: I 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 I: I projection upward from the bottom of the nearest excavation. 5.3.6 Seismic Design Parameters The site is located at approximately 33.1504 Latitude and -117.3460 Longitude. Site spectral accelerations (Ss and SI), for 0.2 and 1.0 second periods for a risk targeted two (2) percent probability of exceedance in 50 years (MCER) were determined using the web interface provided by SEAOC/OSHPD (https://seismicmaps.org) to access the USGS Seismic Design Parameters. We have selected a Site Class "C" based on the old paralic deposits and anticipated depth of fill. SITE SEISMIC PARAMETERS Mapped 0.2 sec Period Spectral Acceleration, Ss 1.159g Mapped 1.0 sec Period Spectral Acceleration, S 1 0.444g Site Coefficient for Site Class "C", Fa 1.000 Site Coefficient for Site Class "C", Fv 1.356 Maximum Considered Earthquake (MCER) Spectral 1.159g Response Acceleration for 0.2 Second, SMs Maximum Considered Earthquake (MCfa) Spectral 0.602g Response Acceleration for 1.0 Second, SM 1 5% Damped Design Spectral Response 0.773g Acceleration Parameter at 0.2 Second, Sos 5% Damped Design Spectral Response 0.402g Acceleration Parameter at I second, So 1 5.3.7 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 "SO" as per Table 19.3.1.1 of ACI 318-14, as such no special recommendations for concrete are included herein. GEOTEK HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California 5.4 RETAINING WALL DESIGN AND CONSTRUCTION 5.4.1 General Design Criteria Project No. 3592-SD October 18, 2019 Pa~e 14 Base on a review of project plans, retaining walls are anticipated to be limited to relatively short stem walls supporting the main house structure, however, in the event changes are made to the plan the recommendations presented herein may apply to typical masonry or concrete vertical retaining walls to a maximum height of IO feet. Additional review and recommendations should be requested for higher walls. 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 2000 psf. 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. The appropriate fluid unit weights are given in the table below for specific slope gradients of retained materials. Surface Slope of Retained Equivalent Fluid Pressure Materials (PCF) (H:V) Select Backfill* Level 35 2:1 55 *Select backfill should consist of native or imported sand other approved materials with an SE> 30 and an El~20. The above equivalent fluid weights do not include other superimposed loading conditions such as expansive soil, vehicular traffic, structures, seismic conditions or adverse geologic conditions. Additional lateral forces can be induced on retaining walls during an earthquake. For level backfill and a Site Class "C", the minimum earthquake-induced force (Feq) should be I OH2 (lbs/linear foot of wall) for cantilever walls. This force can be assumed to act at a distance of 0.6H above the base of the wall , where "H" is the height of the retaining wall measured from the base of the footing (in feet). The 2016 CBC only requires the additional earthquake induced lateral force be considered on retaining walls in excess of six (6) feet in height; GE O TEK C C C C C C C C C C C C C C C C C C HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street. Carlsbad. California Project No. 3592-SD October 18, 20 19 Pa:e 15 however, the additional force may be applied in design of lesser walls at the discretion of the wall designer. 5.4.2 Wall Backfill and Drainage Wall backfill should include a minimum one (I) foot wide section of ¾ to I -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 I: I (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. 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 (I) cubic foot per lineal foot of 3/8 to one (I) 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. Drain outlets should be maintained over the life of the project and should not be obstructed or plugged by adjacent improvements. 5.4.3 Restrained Retaining Walls Any retaining wall that will be restrained prior to placing backfill or walls that have male or reentrant corners should be designed for at-rest soil conditions using an equivalent fluid pressure of 60 pcf (select backfill), plus any applicable surcharge loading. For areas having male or reentrant corners, the restrained wall design should extend a minimum distance equal to twice the height of the wall laterally from the corner, or as otherwise determined by the structural engineer. GEOTEK C C C C C C C C C C C C C C C C C C C .. ····· ··-·-·-·-·------------------------------- HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California 5.5 POST CONSTRUCTION CONSIDERATIONS 5.5.1 Landscape Maintenance and Planting Project No. 3592-SD October 18, 20 19 Paee 16 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. 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 may be warranted and advisable. We could discuss these issues, if desired, when plans are made available. 5.5.2 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. GEOTEK C C C C C C C C C C C C C C C C C C HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California 5.6 PLAN REVIEW AND CONSTRUCTION OBSERVATIONS Project No. 3592-SD October 18, 20 19 Pue 17 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 Geo T ek'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 Geo T ek, which can comply with the requirements of the governmental agencies having jurisdiction over 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. P0801919-SD) dated August 16, 2019 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 GEOTEK C C C C C C C C C C C C C C C C C HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California Project No. 3592-SD October 18, 20 19 Pa.&e 18 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 C C C C C C C C C C C C C C C C C C C ----~--------------------------------- HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street. Carlsbad. California 7. SELECTED REFERENCES Project No. 3592-SD October 18, 20 19 Paee 19 American Society of Civil Engineers (ASCE), 2013, "Minimum Design Loads for Buildings and Other Structures," ASCE/SEI 7-10, Third Printing, Errata Incorporated through March I 5. Armstrong & Brooks Consulting Engineers, 2017, Grading Plans for: 3677 Garfield St, Carlsbad, CA 92008, APN:204-232-04, Sheets I and 2, dated February IS, 2017. 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, 2016 "California Building Code," 3 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. Chereskin Architecture, Plans for Hernandez Residence, 3677 Garfield Street, Carlsbad, California, 92008, 8 Sheets, TS and A-1 through A-7, dated August 14, 2019. GeoTek, Inc., In-house proprietary information. 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. Structural Engineers Association of California/California Office of Statewide Health Planning and Development (SEOC/OSHPD), 2019, Seismic Design Maps web interface, accessed October 19, 2019 at https://seismicmaps.org GEOTEK N Not to Scale Approximat Location Imagery from USGS The National Map, 2019 Hernadez Residence 3677 Garfield Street Carlsbad, CA PN: 3592-SD DATE: October 20 19 Figure I Site Location Map GEOTEK 1384 Poinsettia Avenue, Suite A Vista, Cal ifornia 92081 I I I I I I I I APN: 204-232-0J ' I f 59.9 I I ·., ~ I ~· I I I ~ I I . I ., TC I I ~ (SS.801 (59.72) . (&1.J1ls:~ :\--,-~ -z (60.61) eJ·.J9 J ro 7\ FG \4 _FS __ \ /;rs FS 1 Ii -& --• -59.' ; \-,,;o• ~} . ~-. /qJ ,., '. ., ~~+9 .. "w • -----~ ==, -~ -~ -~ ---. .. • • -SD • ··s· FS tO:l~~---"_'7,J 10 58. FC 56., fE ~ ·ro ; ._~_. 1'f ; ~......,-,,,yi -"'"--G-n rJ •-••-:-•7~-0 t'3.:...w:.---ci-1(=~ ·.:;:<-!lt)..O_ u n: , OONJ< ~~ ""71:0 62 . .JJ FF~ .. • " .. . . 62.JJ r, I . .66 ff ;9_54 1 ~ • 21' (59,.6) FG 158.0 fC , PROP. ~WJER PROP. EL£C11ilC M£1£R I • 1/FS . . . 62.50 FFj 58.0 FG SD SD 58. 0 FG . . \_ 59.50 ·. 62.JJ FF PROP. 1/C. PN) m-@ @)58.0FG/ fS J 580 ~ 7·· f 56.0 IE ., t<i -· n, -• \. • ... ,, . ~5f.lJ ~· _· ~-50 56.0 IE \ F'G ,· 6. -l\'h :ii" -. :2.JJ ff -,.. vud:ll · (59.oJ ro ♦HA-3 59.58 FS .., _ / 6 .50/[ HA-2 _1 ' 1£\ ,g? '2.50 .. 8. FG <;!' '17 ~ ,,.-,q ' "' ~S) "-. vv, __ • 60,'' rs ~ :, -q .... , -Q ,.,. PS . ,q ,q'7 ~ '(:j FS· u., 62.JJ 58.0 c:N"-~ of1 '17 .ND! LDSCP. . . . . . t:>. I v'~.95 TC I ,J I . ,I 59.47 FS 1.09} 1 ~ I tm TC HEW ·. . 11 ·1 l ,;J I ,nsc,, .. ~ 1.11 L;~ 5 1 1tJ-.W,:,.L.I i FS Ii . ~ . 59.7 I.«._ F(l ~ q I~ f.5.9. "~1 TC 1 -.... 98 FS ~ ~ ·--------sl---BSL.----------~------------1 -Q -q -SI> ·v '-,E-<;1 .., _. --~------. ~ ~ 59.80 JS# : 59~1/ 1,s '-'"" ~. --:t. ~ -----FS \ -=-.::=-./~7 Ci V _i_~ V---7r=-/ _,. _____ .,,...____, ______ .,, _____ ---~a.17i LEGEND m · ro m HA-3 ._: Cf.) Q rd rt a:: ~ ro=;, I ----------11 " ♦ Approximate Location of Hand Auger Boring ,---' ,1 APN: 204-232-05 I " " -....... P-1 ~ Approximate Location of Percolation Test Plan adapted from "Precise Grading Plan" by Chereskin Architecture "V ~o 5 Scale: I"= 10' 10 20 Hernadez Residence 3677 Garfield Street Carlsbad, CA PN: 3592-SD DATE: October 2019 Figure 2 Boring Location Map A G EO TEK 1384 Poinsettia Avenue, Suite A Vista, California 92081 ------------ --- -- -... ---... - - ------- APPENDIX A EXPLORATORY HAND AUGER LOGS AND INFILTRATION TESTING WORKSHEETS GEOTEK ---- ------------- ------- - --- ----- HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California A -FIELD TESTING AND SAMPLING PROCEDURES Bulk Samples (Large) Project No. 3592-SD October 18, 2019 Page A-I 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. 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 uses f-c f-m GEOLOGIC B: Attitudes J: Attitudes C: Contact line Unified Soil Classification System Fine to coarse Fine to medium Bedding: strike/dip Joint: strike/dip 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 -CLIENT: Chris & Ramon Hernandez DRILLER: LOGGED BY: BG ----------------------PROJECT NAME: PROJECT NO.: 3677 Garfield 3592-SD DRILL METHOD: Hand Auger HAMMER:-----------O PE RAT OR: RIG TYPE: ________ _ LOCATION: See Boring Location Map ELEVATION: 60ft DATE: 8/21/2019 -SAMPLES 0 Laboratorv Testina -- g ., .c C. .!= E HAND AUGER NO.: HA-1 ~l ~ ~ "' ., ~ >, ~ a -., en iij 'o ., ui C. .c ., -Q) E E en -C ., C. ~ (.) ~! o.e, ,5 0 .. ::, E 0 en z en 2:-0 .. i:ii ::::, 0 0 en MATERIAL DESCRIPTION AND COMMENTS (.) -6" Toosoil and 11rass -Quatema!}'. Old Paralic De12osits --I SP SAND, reddish brown, moist, fine to medium grained, poorly graded El,SR -----\ -- 5 --HOLE TERMINATED AT 5 FT ----No groundwater encountered -Hole backfilled with soil cuttings ------ 10 ----------- 15 ------------- 20 ------------- 25 -------------- 30 ---Q SamRle~Re: • --Ring 1---SPT IZI--Small Bulk ~---Large Bulk □ ---No Recovery ~ --Water Table z Ill .... CJ AL = Attert>erg Limits El = Expansion Index SA = Sieve Analysis RV= R-Value Test Ill Lab testing: _, SR = Sulfate/Resisitivity Test SH= Shear Test CO= Consolidation test MD = Maximum Density - --GeoTek, Inc. -LOG OF EXPLORATORY BORING -CLIENT: Chris & Ramon Hernandez DRILLER: LOGGED BY: BG ---------------------PROJECT NAME: 3677 Garfield DRILL METHOD: Hand Auger O PE RAT OR: -PROJECT NO.: 3592-SD HAMMER: ______ _ RIG TYPE: ________ _ LOCATION: See Boring Location Map ELEVATION: 60ft DATE: 8/21/2019 -SAMPLES 0 Laboratorv TestinQ -.. € " .c Q. .!: E HAND AUGER NO.: HA-2 ~ .?;-~ " ~ >, "iii ~ % "' -" en ~ -aiu " " Q. .c " -Q) E E en -C: " i5. 3: (.) ~~ 0.9, 6 Cl .. ::, E .!2 en z en ~ .. a:, ::, 0 en MATERIAL DESCRIPTION AND COMMENTS (.) Cl ---- -""'""""' 6" Topsoil and !lrass ............. ,,,, ........ J Quatema[l,'. Old Paralic Degosits SP @ 6" SAND, brown to reddish brown, very moist, f-m grained, poorly graded, El,SR @ 24" Probes dense @30" SAND, mottled white, tan, and black, moist, f-m grained, trace silt @36" becomes reddish brown 1@48" Auoer refusal concretion bits in cuttings - 5-HOLE TERMINATED AT 4 FT --Refusal at 4 feet ---No groundwater encountered -Hole backfilled with soil cuttings ------ 10 -------------15 --------------20 ------------- 25 ------------- 30 ----Q Samele tli'.ee: ■ --Ring 1---SPT IZI--Small Bulk ~---Large Bulk □ ---No Recovery ~ --Water Table z w -Cl AL = Attertlerg Limits El = Expansion Index SA = Sieve Analysis RV= R-Value Test w Lab testing: ... SR= Sulfate/Resisitivity Test SH = Shear Test CO = Consolidation test MD = Maximum Density -- ,_ ,_ --------,_ ----,_ -------------,_ -------- CLIENT: PROJECT NAME: PROJECT NO.: LOCATION: SAMPLES §: Q) C. .5 -5 ~ "' Q) ~ -Q) C. Q) l C. .c Q) C. E E 0 E 0 ., ::, ., i:ii en z en GeoTek, Inc. LOG OF EXPLORATORY BORING Chris & Ramon Hernandez DRILLER: LOGGED BY: BG 3677 Garfield 3592-SD ---------DRILL METHOD: Hand Auger HAMMER: ____ ..;;_ __ OPERATOR: ___________ _ RIG TYPE: See Boring Location Map ELEVATION: 59ft DATE: ----a-,2-112-0-19 ___ _ l Laboratorv Testinq ~l ~'E ~n HAND AUGER NO.: HA-3 en en u en :l 1-------M-A-T-ER_I_A_L_D_E_S_C_R_IP_T_IO_N_A_N_D_C_O_M_M_E_NT_S ____ ----l 8 ➔--+----+---+-----1-6_" _T_o._o,s_o_i_l a_n_d_,11, __ ra_s_s __ =-----=~=-___,,,.....,=--...,.,.----------+---+--+-----------t Quaternary Old Paralic Deposits -:\/ --:/\ - 5 --------- 10 ---------- 15 ---------- 20 ---------- 25 ---------- 30 -- Cl Samele n!ee: z l&I CJ l&I Lab testing: ... SM @6" Silty SAND, light brown, dry to slightly moist, f grained, poorly graded Augering becomes difficult, concretion bits/sandstone returned hard though friable @3' Hand augering becomes difficult, friable sandstone concretions returned in cuttinas SP @4' SAND, reddish brown, moist, f-m grained, poorly graded HOLE TERMINED AT 5 FT No groundwater encountered Hole backfilled with soil cuttings El, SR ■ --Ring 1---SPT 0--Small Bulk ~---Large Bulk D ---No Recovery ~ --Water Table AL = Attertierg Limits SR= Sulfate/Resisitivity Test El = Expansion Index SH= Shear Test SA = Sieve Analysis RV= R-Value Test CO = Consolidation test MD = Maximum Density ,._ ..... ---.... ---------... , -... , ---.... ---------------- CLIENT: PROJECT NAME: PROJECT NO.: LOCATION: SAMPLES € QI C. .E t ?: "' J!! m QI i C. .c QI a. E E 0 E "'::, "' ai Cl) z Cl) GeoTek, Inc. LOG OF EXPLORATORY BORING Chris & Ramon Hernandez DRILLER: LOGGED BY: SE ---------------------3677 Garfield DRILL METHOD: Hand Auger O PE RAT OR: 3592-SD HAMMER:----"'----RIG TYPE: ________ _ See Boring Location Map ELEVATION: 59ft DATE: i ~ ~ -JB C: ~~ HAND AUGER NO.: P-1 Cl) u Cl) ::, 1------""M""A""T--ER __ I_A_L __ D .... E"""s"""c __ R __ IP""T--IO .... N,..,.....,.A--N--D-,C:--,O""M"'M=EN_T __ S,---------1 8 10/1/2019 Laboratory Testing ~ Cl) = 0 -+--+----+---+-----f-'-6_" _.;.T.;;..oo._:s;;...o'-il-'a'-n_;_d 11,-"ra-'s'-'s--------~~~------------+---+--+-----------1 Quaternary Old Paralic Deposits -------- 5 --------- 10 ---------- 15 ---------- 20 ---------- 25 ---------- 30 -- C Sam(!le rt(!e: z Ill c:, Ill Lab testing: _, SM @6" Silty SAND, light brown, dry to slightly moist, f grained, poorly graded SP @4' SAND, reddish brown, moist, f-m grained, poorly graded HOLE TERMINED AT 5 FT No groundwater encountered Hole pre-soaked with potable water on 1 0-1-19 Hole backfilled with soil cuttings on 10-2-19 • --Ring 1---SPT IZJ--Small Bulk ~---Large Bulk D ---No Recovery ~ --Water Table AL = Atterberg Limits SR = Sulfate/Resisitivity Test El = Expansion Index SH = Shear Test SA = Sieve Analysis CO= Consolidation test RV= R-Value Test MD = Maximum Density - -------------- -- ------ - ----... ---- Client: Project: Project No: Chris and Ramon Hernandez Hernandez Residence 3592-SD Date: 10/1/2019 Boring No. P-1 Infiltration Rate (Porchet Method) Time Interval, D.t = Final Depth to Water, DF = Test Hole Radius, r = Initial Depth to Water, D0 = Total Test Hole Depth, DT = Equation - Ho= DT-Do= HF= DT-DF = D.H = D.D = H0 -HF = Havg = (H0 +HF)/2 = I= t 1.69 10 40.00 1.75 32 60 D.H (60r) 28.00 20.00 8.00 24.00 GEOTEK Inches per Hour -----------------APPENDIX B -RESULTS OF LABORATORY TESTING ------ -- -- --GEOTEK HERNANDEZ RESIDENCE Preliminary Geotechnical Evaluation 3677 Garfield Street, Carlsbad, California SUMMARY OF LABORATORY TESTING Identification and Classification Project No. 3586-SD October I 8, 20 19 Pa~e B-1 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 Expansion Index Expansion Index testing was performed on two soil samples. Testing was performed in general accordance with ASTM Test Method D 4829. The results of the testing are provided below. Moisture-Density Relationship Laboratory testing was performed on one sample collected during the subsurface exploration. The laboratory maximum dry density and optimum moisture content for the soil type was determined in general accordance with test method ASTM Test Procedure D 1557. The results of the testing are provided below. HA-1/2/3 0-5 Sand with Silt 123.9 9.5 GEOTEK Project X Corrosion Engineering Corrosion Control -Soil, Water, Metallurgy Testing Lab REPORT S 190823A Page I Results Only Soil Testing for Hernandez Residence August 27, 2019 Prepared for: Ben Grenis GeoTek, Inc. 1384 Poinsettia Ave, Suite A Vista, CA, 92081 bgrenis@geotekusa.com Respectfully Submitted, Project X Job#: S190823A Client Job or PO#: 3592-SD Eduardo Hernandez, M.Sc., P.E. Sr. Corrosion Consultant NACE Corrosion Technologist #16592 Professional Engineer California No. M37102 ehernandez@projectxcorrosion.com 29990 Technology Dr, Suite 13, Murrieta, CA 92563 Tel : 213-928-7213 Fax: 95 1-226-1 720 www.projectxcorrosion.com Project X Corrosion Engineering Corrosion Control -Soil, Water, Metallurgy Testing Lab Soil Analysis Lab Results Client: GeoTek, Inc. Job Name: Hernandez Residence Client Job Number: 3592-SD Project X Job Number: S 190823A August 27, 2019 Method ASTM D4327 Bore#/ Depth Sulfates Descrintion S04 2- (ft) (m!!/k!!) <wt%) B1/2/3 0.0-5.0 40.1 0.0040 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 I NT = Not Tested I Unk = Unknown Chemical Analysis performed on I :3 Soil-To-Water extract 29990 Technology Dr., Suite 13, Murrieta, CA 92563 Tel: 213-928-7213 Fax: 951-226-1720 www.projectxcorrosion.com Page 2 .. .. .. Ill .. .. .. .. .. 1111 ... .. ... 1111 .. 11111 111111 ... .. 11111 ... 1111 .. .. ... ... II. ... APPENDIX C GENERAL EARTHWORK GRADING GUIDELINES GEOTEK .. .. 1111 .. 1111 .. .. .. .. .. 1111 .. 1111 ... 1111 ... .. ... .. .. .. 1111 -1111 .. .. .. .. .. 1111 .. .. .. .. .. .. Grading Guidelines APPENDIXC Page I 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. 2. 3. 4. 5 . 6 . 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 . 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 . 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 . Density tests may be made on the surface material to receive fill, as considered warranted by this firm . 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 . 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 GEOTEK -.. 11111 .. -.. 11111 .. .. .. .. .. .. .. .. .. ... .. .. -.. -.. .. 1111 -.. .. .. .. .. ... Grading Guidelines APPENDIXC Page2 7. 8 . 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 ofoperational changes that might result in different source areas for materials . 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. Finish grade testing of slopes and pad surfaces should be performed after construction is complete. Site Clearing 1. 2. 3 . 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. 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. 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. 2. 3. 4 . 5. 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 . 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. 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 . 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. 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 . GEOTEK -.. -.. -.. -.. .. .. .. .. .. iii, ... .. .. .. .. .. 1111111 .. 1111111 .. ,.. 111111 Grading Guidelines APPENDJXC Page3 2. 3. 4. 5. 6. 7 . 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 . Filter material should be clean, 1/2 to I-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 . 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 . All subdrainage systems should be observed by our representative during construction and prior to covering with compacted fill. Subdrains should outlet into storm drains where possible. Outlets should be located and protected. The need for backflow preventers should be assessed during construction . Consideration should be given to having subdrains located by the project surveyors. Fill Placement I. 2 . 3 . 4. 5. 6. 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 ofreport). 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 . 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 . 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. 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. 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. GEOTEK .. Ill .. 1111 .. .. .. ... 11111 ... 1111111 ~ ~ Grading Guidelines APPENDIXC Page4 Slope Construction I. 2. 3. 4. 5. 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. 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. 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. Corners and bends in slopes should have special attention during construction as these are the most difficult areas to obtain proper compaction. 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. I. 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 . 3. 4. 5. 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 b) c) interface. A key at least one (I) equipment width wide (or as needed for compaction) and tipped at least one (I) foot into slope should be excavated into competent materials and observed by our representative. 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.) 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. A basal key is needed for fill slopes extending over natural slopes. A schematic diagram for this condition is presented on Plate G-2. 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. GEOTEK .. 11111 .. .. .. .. .. 11111 ... - ... .. ... .. 1111 JIii ... 1111 1111 1111 .. 1111 11111 1111 1111 11111 .. Grading Guidelines APPENDIXC Page5 1. 2 . 3. 4. 5 . 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. On longer slopes backcuts and keyways should be excavated in maximum 250 feet long segment. The specific configurations will be determined during construction. 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. 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. Benching of backcuts during fill placement is required. Lot Capping 1. 2. 3. 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 . 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. 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 oflarger 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. 2. 3. 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 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). 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. GEOTEK 11111 ... 11111 ... .. 11111 ... ... ... ... .. ... ... ... ... .. .. .. .. ... ' .. 11111 Ill ... 11111 .. .. .. ... ... 1111111 ... Grading Guidelines APPENDIXC Page6 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) c) d) The over size rock trenches should be no closer together than 15 feet from any slope face. 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. 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. 3 . 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. 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. 2 . 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.) Rock fill should be generously watered (sluiced) a) Water should be applied by water trucks to the: i) dump piles, GEOTEK .. .. .. ... ... ,,. ... "" ... ... 11111 ... jllll I ... .. ... .. ... .. .. .. Grading Guidelines APPENDIXC Page 7 3. 4 . 5. 6. 7 . b) c) d) ii) front face of the lift being placed and, iii) surface of the fill prior to compaction. No material should be placed without adequate water. The number of water trucks and water supply should be sufficient to provide constant water. 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. 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. 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. 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 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. 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 . GEOTEK .. ... .. ... ... ... ... .. ... ~ ... ... .. ... .. ... Ill .. .. ... Grading Guidelines APPENDIXC Page8 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. I. 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 . 3. 4 . 5. 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 . 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 . Sand backfill should not be allowed in exterior trenches adjacent to and within an area extending below a I: I projection from the outside bottom edge of a footing, unless it is similar to the surrounding soil. 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 . GEOTEK --.. ... .. .. ... .. ... ... ... ... .. ... .. ... .. 1111"' ... 1111"' ... -.. .. .. .. ... ... 1111"' ... 1111"' Grading Guidelines APPENDJXC Page9 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 . I. Safety Meetings: Our field personnel are directed to attend the contractor's regularly scheduled safety meetings. 2 . 3. Safety Vests: Safety vests are provided for and are to be worn by our personnel while on the job site . 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 . GEOTEK .. -... .. ... ... .. .. .. .. ... .. ... ... .. ... ... ... .. .. .. 111111 .. 1111 .. .. .. .. .. Grading Guidelines TEST PIT SAFETY PLAN Test Pit ' 50 ft Zone of Traffic Direction Non-Encroachment p Vehicle r Test Pit arked here ' ◄ 10 Oft Zone of Non-Encroachment I 50 ft Zone of Non-Encroachment '' Slope Tests SIDE VIEW "' Spoil pile '\. ~ APPENDJXC Page JO 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. GEOTEK .. .. ,. ... ,.. ... .. ... ... 1111 ... ,.. I ... I"" I ... .. 111111 .. Grading Guidelines Procedures APPENDIXC Page 11 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. GEOTEK