Loading...
HomeMy WebLinkAboutPD 2020-0007; FUKUDA ADDITION; PRELIMINARY GEOTECHNICAL INVESTIGATION; 2020-10-16gwrd Co" 10(1 PRELIMINARY GEOTECHNICAL INVESTIGATION 1U%(140A (T(O&J ?926 20 - 0001 D&2c-2R 3R o2O—cOl( Proposed Second Story Addition and Basement 2726 Morning Glory Lane Carlsbad, California Prepared For: Lane Fukuda 2726 Morning Glory Lane Carlsbad, California 92008 Prepared By. Coast Geotechnical P.O. Box 230163 Encinitas, California 92023 June 18, 2019 W.O.707419 COAST GEOTECHNICAL CONSULTING ENGINEERS AND GEOLOGISTS ()COAST GEOTECHNICAL CONSULTING ENGINEERS AND GEOLOGISTS June 18, 2019 W.O. 707419 Lane Fukuda 2726 Morning Glory Lane Carlsbad, California 92008 RE: PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed Second Story Addition and Basement 2726 Morning Glory Lane Carlsbad, California Dear Mr. Fukuda: In response to your request and in accordance with our Agreement dated April 30, 2019, we have performed a preliminary geotechnical investigation on the subject property for the proposed second story addition and basement. The findings of the investigation, laboratory test results, and recommendations for the foundation design are presented in this report. From a geologic and soils engineering point of view, it is our opinion that the site is suitable for the proposed development, provided the recommendations in this report are implemented during the design and construction phases. However, certain geotechnical conditions will require special consideration during the design and construction phases, as indicated by the following: The subject property is located in an area that is relatively free of potential geologic hazards such as landsliding, high groundwater conditions, liquefaction and seismically induced subsidence. The proposed addition will not adversely affect the adjacent properties provided the recommendations of this report are implemented. Preliminary plans suggest that excavations ranging up to 8.0 feet are planned for the proposed basement. It is anticipated that the proposed excavation will extend though the surficial materials and into the underlying Very Old Paralic Deposits. However, should loose deposits be encountered along the base of the excavation, scarification and compaction for slab support will be necessary. Additional recommendations during the grading phase will be required. Proposed retaining wail footings should extend through the scarification, if required, and be founded the designed depth into competent Very Old Paralic Deposits. Temporary slopes should be trimmed at a gradient of 1:1 (horizontal to vertical) above a 5.0 foot vertical or less depending upon conditions revealed during grading. In areas where the temporary slopes cannot be graded, alternate five(5) foot wide slot cuts in a 1:1 (horizontal to vertical) temporary slope may be used for wail construction. Temporary support for the patio column pad footing will also be required. Due to the proximity of the garage and covered patio to the proposed basement, the subterranean walls should be constructed in alternate five (5) (not to exceed 6.0 feet) wide slot cuts. The existing foundation, where exposed, suggests that the residential footings are founded approximately 24 inches below grade and into dense Very Old Paralic Deposits. Based on limited exposures and laboratory testing the existing footings, from ageotechnical viewpoint, are suitable for the support of proposed secondary loads, without underpinning. If you have any questions, please do not hesitate to contact us at (858) 755-8622. This opportunity to be of service is appreciated. Respectfully submitted, COAST GEOTECHNICAL /W, Y' 0 - 0441W Kevin McFarland Project Geologist Mark Burwell, C.E.G. Engineering Geologist V t h aTa S &in g 4h Jet, P. E. Geotechnical Engineer TABLE OF CONTENTS INTRODUCTION .......................................................... 5 SCOPE OF SERVICES ..................................................... s SITE DESCRIPTION AND PROPOSED DEVELOPMENT ......................6 3.1 Site Description ......................................................... 6 3.2 Proposed Development ................................................... 7 SITE INVESTIGATION AND LABORATORY TESTING .......................7 4.1 Site Investigation ........................................................ 7 4.2 Laboratory Testing and Analysis ............................................ 7 GEOLOGIC CONDITIONS ................................................. 8 5.1 Regional Geologic Setting ................................................8 5.2 Site Geology ...........................................................8 5.3 Expansive Soil .................................................... 5.4 Groundwater Conditions .................................................. 9 GEOLOGIC HAZARDS ...................................................10 6.1 Faulting and Seismicity .................................................. 10 6.2 Landslide Potential .....................................................11 6.3 Liquefaction Potential........................... . ...................... 12 6.4 Flood Potential ................................................... . . . . . 12 6.5 Tsunami Potential ...................................................12 CONCLUSIONS .......................................................... 12 RECOMMENDATIONS ...................................................13 8.1 Grading/Removals/Recompaction .........................................13 8.2 Temporary Slopes/Excavation Characteristics................................14 8.3 Slot Cuts .............................................................14 8.4 Foundations ........................................................... 14. 8.5 Sulfate and Chloride Tests ...............................................15 8.6 Slabs on Grade (Interior and Exterior) ......................................16 8.7 Lateral Resistance ...................................................... 16 8.8 Retaining Walls ......................................................17 8.9 Dynamic (Seismic) Lateral Earth Pressures ..................................17 8.lO Settlement Characteristics ................................................ 18 8.11 Seismic Considerations .................................................18 8.l2 Preliminary Pavement Design ...................................19 8.13 Permeable Interlocking Concrete Payers (PICP)..............................19 8.14 Utility Trench ......................................................... 21 8.15 Drainage .21 8.16 Geotechnical Observations .21 8.17 Plan Review .......................................................... 21 9. LIMITATIONS ........................................................... 22 REFERENCES..............................................................23 FIGURES Figure 1: Site Location Map Figure 2: Geotechnical Map Figure 3: Geological Cross Section A-A' Figure 4: Geological Cross Section B-B' Figure 5: Regional Fault Map Figure 6: Flood Potential Figure 7: Excavation Detail Figure 8: Typical Isolation Joints Figure 9: Basement Wall Drainage Detail Figure 10: Typical Permeable Paver Detail APPENDIX A Logs of Boring/Test Pits APPENDIX B Laboratory Test Results APPENDIX C Seismic Design Response Parameters APPENDIX D Grading Guidelines COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 5 of 24 1. INTRODUCTION This report presents the results of our background review, subsurface investigation, laboratory testing, geotechnical analyses and conclusions regarding the conditions at 2726 Morning Glory Lane, and recommendations for design and construction. The purpose of this study is to evaluate the nature and characteristics of the earth materials underlying the property, the engineering properties of the surflcial deposits and their influence on the proposed second story addition and basement. SCOPE OF SERVICES The scope of services provided included a review of background data, reconnaissance of the site geology, and engineering analysis with regard to the proposed second story addition. The performed tasks specifically included the following: Reviewing geologic and hazard (seismic, landslide, and tsunami) maps, recently published regarding the seismic potential of nearby faults, and a site plan for the project. All background data is listed in the References portion of this report. Performing a site reconnaissance, including the observation of geologic conditions and other hazards, which may impact the proposed project. Excavation of an exploratory boring and two test pits consisting of drilling, logging, and sampling of earth materials to evaluate the subsurface conditions. Performing geotechnical laboratory testing of recovered soil samples. Analyzing data obtained from our research, subsurface exploration, and laboratory testing. 0 Preparing this preliminary report. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 7 of 24 elevation. The second pad, at approximately 157 feet in elevation, consists of a large existing pool and spa, barbeque area, small pond, and a small storage container to the southeast corner. The site is bounded along the west by Morning Glory Lane, the east by Las Flores Drive, and the north and south by existing lots with residences. Drainage is generally by sheet flow to the west towards Morning Glory Lane. 3.2 Proposed Development Preliminary architectural plans for the development of the site were prepared and drawn by Stephanie Lupton, drafter. The project site is anticipated to include an attached guest room on the southeast end of the residence with a basement storage and an expanded garage with a proposed covered deck over the southwest end of the residence. 4. SITE INVESTIGATION AND LABORATORY TESTING 4.1 Site Investigation Geotechnical conditions of the property were evaluated by surface observations and the excavation of an exploratory boring drilled with a track-mounted hollow stem drill rig and test pits hand dug with a shovel and auger on May 3, 2019. The boring, designated as B- 1, was drilled on the ground surface on the southeast of the existing residence in the back yard lawn area. The two test pits, designated as TP-1 and TP-2, were hand dug to expose the footing on the west and south sides of the existing residence. The boring and excavations were logged by our project geologist who also retained representative soil and rock samples at selected locations and intervals for subsequent laboratory testing. Approximate boring locations are depicted on the enclosed Geotechnical Map, Figure 2. Logs of Boring and Test Pits are included in Appendix A. Laboratory test results and engineering properties of selected samples are summarized in the following sections and in Appendix B: Laboratory Test Results. 4.2 Laboratory Testing and Analysis Earth deposits encountered in our exploratory boring excavations were closely examined and sampled for subsequent laboratory testing. The laboratory tests were performed in accordance with the generally accepted American Society for Testing and Materials (ASTM) test methods or suggested procedures. All lab descriptions and results can be found in the Test Results section of Appendix B. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 8 of 24 The following tests were performed: Classification of Soils Grain Size Analysis Moisture/Density Maximum Dry Density and Optimum Moisture Content Expansion Index Test Sulfate Ion Content Chloride Ion Content pH Test Shear Test Consolidation Test 5. GEOLOGIC CONDITIONS 5.1 Regional Geologic Settings The subject property is located in the Coastal Plains subdivision of the Peninsular Ranges geomorphic province of San Diego. The coastal plain area is characterized by Pleistocene marine terrace landforms. These surfaces are relatively flat erosional platforms that were shaped by wave action along the former coastlines. The step-like elevation of the marine terraces was caused by changes in sea level throughout the Pleistocene and by seismic activity along the Newport- Inglewood/Rose Canyon Fault Zone located west of the coastline. The Newport-Inglewood Fault Zone is one of many northwest trending, sub-parallel faults and fault zones that traverse the nearby vicinity. Several ofthese faults, including the Newport-Inglewood Fault Zone, are considered active faults. Further discussion of faulting in regards to the site is discussed in the Geologic Hazards section of this report. 5.2 Site Geology Previously published geologic maps conducted by Kennedy and Tan (2008) indicate that the subject property is underlain at depth by Very Old Paralic Deposits (Qvop). The Paralic Deposits are underlain by Eocene-age Torrey Sandstone (Tt). As exposed from the exploratory boring in the back yard lawn, there consists a very thin layer, up to 1 foot, of topsoil underlain by Very Old Paralic Deposits. End of B-i occurred at a depth of 13 feet and TP-1 and TP-2 ended at 2 feet. Geologic COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 9 of 24 Cross-Sections A-A' and B-B' illustrating subsurface profiles based on our exploratory boring and test pits and existing site topography are attached to this report as Figures 3 and 4, found at the end of this report and before the appendices. A brief description of the earth materials encountered on the site follows: Topsoil (Qs): A very shallow section of brown fine to medium grained sand topsoil mantles the underlying Very Old Paralic Deposits. As exposed in our exploratory boring, the topsoil mantle was measured to be on the order of 1.0 foot total depth. The topsoil mantle was mostly found in a moist and very loose condition. Very Old Paralic Deposits (Qvop): The Topsoil is underlain by Quaternary age Very Old Paralic Deposits. This unit consists of orangish brown to dark brown, medium to coarse grained silty sand from 1 foot to the end of the boring at 13 feet. The Very Old Paralic Deposits is very moist and dense throughout the boring. At depth, the density increases and the color changes to dark brown sand with some hard sandstone. Bedding within the Very Old Paralic Deposits is indistinct and the Pleistocene sediments are considered flat-lying. Dense Very Old Paralic Deposits are considered suitable for foundation support and support of fills. 5.3 Expansive Soil Based on our experience in the area and laboratory testing, the Very Old Paralic Deposits reflect an expansion potential in the very low range based on ASTM D4829. 5.4 Groundwater Conditions The area has no groundwater data available. However, due to the location of the property, high groundwater conditions are not anticipated to be a constraint to the grading procedures. However, it should be noted that seepage problems can develop after completion of construction. These seepage problems most often result from drainage alterations, landscaping, and over-irrigation. In the event that seepage or saturated ground does occur, it has been our experience that they are most effectively handled on an individual basis. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 10 of 24 6. GEOLOGIC HAZARDS 6.1 Faulting and Seismicity The subject site is located within the seismically active Southern California region, which is generally characterized by northwest trending, right-lateral strike-slip faults and fault zones. Several of these fault segments and zones are classified as active by the California Geologic Survey (Aiquist-Priolo Earthquake Fault Zoning Act.) As a result, ground shaking is a potential hazard throughout the region. Based on a review of published geologic maps, no known active faults traverse the site (Figure 5). Thus, ground surface rupture is not likely to occur as a result of an earthquake or seismic event. The nearest active fault to the site is the Newport-Inglewood Fault Zone, located approximately 5.2 miles west of the site. It should be noted that the Newport-Inglewood Fault is one of four main fault strands that make up the Newport-Inglewood/Rose Canyon (NIRC) fault system (Treiinan, 1984). The four strands form a series of right-stepping en echelon faults situated along the Southern California coastline. A recent study by Sahakian et al. (2017) concluded that the geometry of the NIRC fault system may enable rupture along the entire length of the fault zone. The study also modeled several rupture scenarios in light of the newly defined geometry which suggest earthquake ruptures up to magnitudes (M) of 7.4 are possible along the NIRC system. While the models are intriguing, the paper recommends further research and modeling on the NIRC fault geometry to improve our understanding of potential hazards and ground shaking along the Southern California coast. The proximity of major faults to the site, and their estimated maximum earthquake magnitudes and peak site accelerations are enclosed on Table 1 and were determined by EQFAULT version 3.00 software (Blake, 2000). COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 11 of 24 Table 1: Principal Active Faults Fault Name Approximate Distance from site (mi) Maximum EQ Magnitude (Mmax) Peak Site Accel. (g) NEWPORT-INGLEWOOD 5.2 6.9 .371 ROSE CANYON 5.5 6.9 .365 CORONADO BANK 21.6 7.4 .218 ELSrNORE-TEMECULA 23.4 6.8 .155 ELSINORE-JULIAN 23.7 7.1 .178 ELSINORE-GLENNY 32.7 6.8 .117 PALOS VERDES 35.5 7.1 .129 The Newport-Inglewood Fault is capable of generating a magnitude earthquake which would cause strong ground motions at the subject site. Further analysis on seismicity and the site specific seismic parameters are discussed in the Recommendations chapter ofthis report and in Appendix C: Seismic Design Parameters. 6.2 Landslide Potential A landslide is the displacement of a mass of rock, debris, or earth down a slope caused by topographic, geological, geotechnical and/or subsurface water conditions. Potential landslide hazards for the site were assessed using the review of published geologic and topographic maps for the area. No landslides have been mapped on or in the immediate vicinity of the subject property. No evidence of deep-seated instability was observed on the site. According to the Landslide Hazards map, Encinitas Quadrangle (Tan and Giffen, 1995), the site is located within Susceptibility Area 3-1 where slopes are generally susceptible. Owning to the minimal topographic relief on the site and the characteristics of the Very Old Paralic Deposits, the potential for deep-seated instability is considered very low. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 12 of 24 6.3 Liquefaction Potential Liquefaction is a process by which a sand mass loses its shearing strength completely and flows. The temporary transformation of the material into a fluid mass is often associated with ground motion resulting from an earthquake, and high groundwater conditions. Owing to the dense nature of the Very Old Paralic Deposits and the anticipated depth to groundwater, the potential for seismically-induced liquefaction and soil instability is considered low. 6.4 Flood Potential The site is not located in the 100-year flood zone according to FEMA Flood Map Service Center (Figure 6). 6.5 Tsunami Potential Tsunamis are large sea waves generated by earthquakes, volcanic eruptions, or landslides that potentially cause the displacement of substantial volumes of water. The Tsunami Inundation Map for Emergency Planning: Encinitas Quadrangle (California Emergency Management Agency, 2009) suggests that the site is not susceptible to flooding from tsunamis. 7. CONCLUSIONS Based on the results from our evaluation of the site, construction of the proposed addition is feasible, provided the recommendations within this report are incorporated in the design and construction of the project. The following geotechnical considerations for the project site include: The subject property is located in an area that is relatively free of potential geologic hazards such as landsliding, high groundwater conditions, liquefaction and seismically induced subsidence. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 13 of 24 Preliminary plans suggest that excavations ranging up to 8.0 feet are planned for the proposed basement. It is anticipated that the proposed excavation will extend though the surficial materials and into the underlying Very Old Paralic Deposits. However, should loose deposits be encountered along the base of the excavation, scarification and compaction for slab support will be necessary. Additional recommendations during the grading phase will be required. Proposed retaining wall footings should extend through the scarification, if required, and be founded the designed depth into competent Very Old Paralic Deposits. Temporary slopes should be trimmed at a gradient of 1:1 (horizontal to vertical) above a 5.0 foot vertical or less depending upon conditions revealed during grading. In areas where the temporary slopes cannot be graded, alternate five (5) foot wide slot cuts in a 1:1 (horizontal to vertical) temporary slope may be used for wall construction (see Figure 7). Temporary support for the patio column pad footing will also be required. Due to the proximity of the garage and covered patio to the proposed basement, the subterranean walls should be constructed in alternate five (5) foot (not to exceed 6.0 feet) wide slot cuts (see Figure 7). The existing foundation, where exposed, suggests that the residential footings are founded approximately 24 inches below grade and into dense Very Old Paralic Deposits. Based on limited exposures and laboratory testing the existing footings, from a geotechnical viewpoint, are suitable for the support of proposed secondary loads, without underpinning. 8. RECOMMENDATIONS 8.1 Grading/Removals/Recompaction Proposed grading is predominately an excavation for the proposed basement. However, slabs on grade and exterior improvements located outside the basement perimeter will require soil and weathered Very Old Paralic Deposits to be removed and replaced as properly compacted fill. Removals are anticipated to be on the order of 12 inches. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 14 of 24 Most of the existing deposits are suitable for reuse, provided they are cleared of all vegetation, debris, and thoroughly mixed. Prior to the placement of fill, the base of the removal should be observed by a representative of this firm. Additional overexcavation and recommendations may be necessary at that time. The exposed bottom should be scarified to a minimum depth of 6.0 inches, moistened as required and compacted to a minimum of 90 percent of the laboratory maximum dry density. Fill should be placed in 6.0 to 8.0 inch lifts, moistened to approximately 1.0 - 2.0 percent above optimum moisture content and compacted to a minimum of 90 percent of the laboratory maximum dry density. Fill, soil, and weathered Very Old Paralic Deposits in areas of proposed concrete flatwork and driveways should be removed and replaced as properly compacted fill. Imported fill, if necessary, should consist of non-expansive granular deposits approved by the geotechnical engineer. 8.2 Temporary Slopes/Excavation Characteristics Temporary excavations, up to 8.0 feet, should be trimmed to a gradient of 1:1 (horizontal to vertical) or less depending upon conditions encountered during grading above a 5.0 foot vertical. The temporary slope recommendations assume no surcharges are located or will be placed along the top of slope within a horizontal distance equal to one half the height of the slope. Where structures or other constraints prevent the temporary slope, alternate slot cuts will be required. The Pleistocene Very Old Paralic Deposits may contain hard concretion layers. Based on our experience in the area, the deposits are rippable with conventional heavy earth moving equipment in good working order. 8.3 Slot Cuts Temporary slopes adjacent to the existing covered patio and garage should be excavated at a gradient of 1:1 (horizontal to vertical). The 15+ foot wide span should be excavated vertically in alternate 5.0 foot wide (not to exceed 6.0 feet) slot cuts. The ABC slot cuts are graphically illustrated on Figure 6. A column pad which supports the covered patio is located in the central portion of the ABC slot cuts. The column pad will require temporary support for wall construction. The retaining wall may be constructed in the alternate AC slot cuts prior to the excavation of slot cut B. The wall segments should be structurally tied together, as recommended by the project structural engineer. 8.4 Foundations The following design parameters are based on footings founded into competent Very Old Paralic Deposits or approved compacted fill. Footings for the proposed structure should be a minimum of 12 inches and 15 inches wide and founded a minimum of 12 inches and 18 inches below the lower most adjacent subgrade at the time of foundation construction and into competent Very Old Paralic COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 15 of 24 Deposits or approved compacted fill for single-story and two-story structures, respectively. A 12 inch by 12 inch grade beam or footing should be placed across the garage opening. New footings should be reinforced with a minimum of four No.4 bars, two along the top of the footing and two along the base. Where parallel wail footings occur, the upper footing should be deepened below a 45-degree plane projected up from the base of the lower footing, or the lower wall should be designed for the additional surcharge load from the upper wall. Footing recommendations provided herein are based upon underlying soil conditions and are not intended to be in lieu of the project structural engineer's design. For design purposes, an allowable bearing value of 2000 pounds per square foot and 2500 pounds per square foot may be used for foundations at the recommended footing depths for single and two story structures, respectively. Proposed footings should be deepened below the scarification zone, ifrequired, and founded the designed depth into competent Very Old Paralic Deposits for basement wall foundations. For footings deeper than 18 inches, the bearing value may be increased by 250 pounds per square foot for each additional 6.0 inches of embedment to a maximum of 3000 pounds per square foot. The bearing value may be increased by one-third for the short durations of loading, which includes the effects of wind and seismic forces. The bearing value indicated above is for the total dead and frequently applied live loads. This value may be increased by 33 percent for short durations of loading, including the effects of wind and seismic forces. 8.5 Sulfate and Chloride Tests The results of our sulfate, chloride, pH and resistivity tests performed on representative samples are presented in Appendix B. The results of testing on selected samples suggest a pH of 8.3 and the amount of water soluble chloride, in soil, is 0.0 19 percent by weight. The amount of water soluble sulfate is 0.017 percent by weight which is classified as negligible according to ACI 318 (SO Exposure Class with Not Applicable Severity). Coast Geotechnical does not practice in the field of corrosion engineering. Further evaluation by a corrosive engineer may be performed if improvements that could be susceptible to corrosion are planned. COAST GEOTECHMCAL Lane Fukuda W.O. 707419 Page 16 of 24 8.6 Slabs on Grade (Interior and Exterior) Slab on grade should be a minimum of 5.0 inches thick and reinforced in both directions with No. 3 bars placed 18 inches on center in both directions. Exterior slabs on grade should be a minimum of 4.5 inches thick and reinforced with No. 3 placed 18 inches on center in both directions. The slab should be underlain by a minimum 2.0-inch coarse sand blanket (S.E. greater than 30). Where moisture sensitive floors are used, a minimum 10.0-mil Visqueen, Stego, or equivalent moisture barrier should be placed over the sand blanket and covered by an additional two inches of sand (S.E. greater than 30). Utility trenches underlying the slab may be backfllled with on-site materials, compacted to a minimum of 90 percent of the laboratory maximum dry density. Slabs should be reinforced as indicated above the provided with saw cuts/expansion joints, as recommended by the project structural engineer. All slabs should be cast over dense compacted subgrades. At a minimum, interior slabs should be provided with soficut contraction/control joints consisting of sawcuts spaced 10 feet on center maximum each way. Cut as soon as the slab will support the weight of the saw, and operate without disturbing the final finish, which is normally within two hours after final finish at each control joint location or 150 psi to 800 psi. The softcuts should be a minimum of 3/4 inch in depth, but should not exceed 1 inch deep maximum. Anti-ravel skid plates should be used and replaced with each blade to avoid spalling and raveling. Avoid wheeled equipment across cuts for at least 24 hours. Provide re-entrant corner (270 degree corners) reinforced for all interior slabs consisting of minimum two, 10-feet long No.3 bars at 12 inches on center with the first bat placed 3 inches from re-entrant corner (see Figure 8). Re-entrant corners will depend on slab geometry and/or interior column locations. Exterior slabs should be provided with weakened planejoints at frequent intervals in accordance with the American Concrete Institute (ACI) guidelines. Our experience indicates that the use of reinforcement in slabs and foundations can reduce the potential for drying and shrinkage cracking. However, some minor cracking is considered normal and should be expected as the concrete cures. Moisture barriers can retard, but not eliminate moisture vapor movement from the underlying soils up through the slab. & 7 Lateral Resistance Resistance to lateral load may be provided by friction acting at the base foundations and by passive earth pressure. A coefficient of friction of 0.35 may be used with dead-load forces. Design passive earth resistance may be calculated from a lateral pressure corresponding to an equivalent fluid density of 300 pounds per cubic foot with a maximum of 2500 pounds per square foot. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 17 of 24 8.8 Retaining Walls Cantilever walls (yielding) retaining nonexpansive granular soils may be designed for an active-equivalent fluid pressure of 37 pounds per cubic foot for a level surcharge and 47 pounds per cubic foot for a sloping backfill. Restrained walls (nonyielding) should be designed for an "at-rest" equivalent fluid pressure of 60 pounds per cubic foot. Wall footings should be designed in accordance with the foundation design recommendations. All retaining walls should be provided with adequate backdrainage system (see Figure 9). In order to reduce infiltration of water through joints in the wall, created by the slot cut method of construction, a waterproofing membrane composed of bentonite should be adhered to the back of the wall. A geocomposite blanket drain such as Miradrain 6000 or equivalent is recommended behind walls. The soil parameters assume a nonexpansive select granular backfill compacted to a minimum of 90 percent of the laboratory maximum dry density. 8.9 Dynamic (Seismic) Lateral Earth Pressures For proposed restrained walls (non-yielding), potential seismic loading should be considered. For smooth rigid walls, Wood (1973) expressed the dynamic thrust in the following form: APe = khYH2 (nonyielding) where kh is 1/2 peak ground acceleration equal to 50 percent of the design spectral response acceleration coefficient (Sds) divided by 2.5 per C.B.C. (2007), Y is equal to the unit weight of backfill, and H is equal to the height of the wall. The pressure diagram for this dynamic component can be approximated as an inverted trapezoid with stress decreasing with depth. The point of application of the dynamic thrust is at a height of 0.6 above the base of the wall. The magnitude of the resultant is: APe = 19.8 H2 (nonyielding) This dynamic component should be added to the at-rest static pressure for seismic loading conditions. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 18 of 24 For cantilever walls (yielding), Seed and Whitman (1970) developed the dynamic thrust as: Pe = 3/8 khYH2 (yielding) The pressure diagram for this dynamic component can be approximated as an inverted trapezoid with stress decreasing with depth and the resultant at a height of 0.6 above the base of the wall. The magnitude of the resultant is: iPe = 7.4 H2 (yielding) This dynamic component should be added to the static pressure for seismic loading conditions. 8.10 Settlement Characteristics Estimated total and differential settlement over a horizontal distance of 30 feet is expected to be on the order of 1.0 inch and 34 inch, respectively. It should also be noted that long term secondary settlement due to irrigation and loads imposed by structures is anticipated to be ¼ inch. 8.11 Seismic Considerations Although the likelihood of ground rupture on the site is remote, the property will be exposed to moderate to high levels of ground motion resulting from the release of energy should an earthquake occur along the numerous known and unknown faults in the region. The Newport/Inglewood Fault Zone located approximately 5.2 miles west of the property is the nearest known active fault, and is considered the design fault for the site. In addition to the Newport-Inglewood Fault, several other active faults may affect the subject site. Seismic design parameters were determined as part of this investigation in accordance with Chapter 16, Section 1613 of the 2016 California Building Code (CBC) and ASCE 7-10 Standard using the web-based United States Geological Survey (USGS) Seismic Design Tool. The generated results for the parameters are presented on Table 2. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 19 of 24 Table 2: Seismic Design Parameters Factors Values Site Class D Seismic Design Category 1/11/111 Site Coefficient, Fa 1.047 Site Coefficient, F 1.565 Mapped Short Period Spectral Acceleration, S 1.133 Mapped One-Period Spectral Acceleration, S1 0.435 Short Period Spectral Acceleration Adjusted for Site Class, 5MS 1.186 One-Second Period Spectral Acceleration Adjusted for Site, SMI 0.681 Design Short Period Spectral Acceleration, SDS 0.791 Design One-Second Period Spectral Acceleration, SDI 0.454 8.12 Preliminary Pavement Design The following pavement section is recommended for proposed driveways: 4.0 inches of asphaltic paving or 5.5 inches of concrete on 6.0 inches of select bas (Class 2) on 12 inches of compacted subgrade soils Subgrade soils should be compacted to the thickness indicated in the structural section and left in a condition to receive base materials. Class 2 base materials should have a minimum R-value of 78 and minimum sand equivalent of 30. Subgrade soils and base materials should be compacted to a minimum of 95 percent of their laboratory maximum dry density. 8.13 Permeable Interlocking Concrete Payers (PICP) Permeable Interlocking Concrete Payers (PICP), ifproposed, should consider several design aspects. Foundations adjacent to or in close proximity to PICP should be protected by an impervious membrane extending a minimum of 5.0 lateral feet from the foundation under the pavement section. The intent is to reduce lateral migration of infiltrated drainage and potential impaction on footings. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 20 of 24 However, this approach is considered less desirable from a geotechnical viewpoint than lining the section with an impervious liner. Pavement underdrains are recommended and should be incorporated in the design for proper collection and disposal of filtrated storm water as indicated on Figure 10. If subdrains are not allowed for storm water infiltration by reviewing agencies, the long term effects of infiltrated water on structural foundations and slabs cannot be predicted with any degree of certainty. PICP pavement structural section (Driveways) should consist of31/a inch PICP, over a minimum of 2.0 inches of ASTM No.8 bedding course/choke stone, over a minimum of 8.0 inches ofASTM No. 57 stone base course, over a minimum of 12 inches of 95 percent compacted subgrade. Bedding course/choke stone and base course stone should also be well compacted, consolidated, and interlocked (avoid crushing the underdrain pipes) with heavy construction equipment. ASTM No. 8, No. 9 or No. 89 should be used for joint materials, depending on the joint size and per manufacturer recommendations. The above stone base section may be reduced from 12 inches to a minimum of 6.0 inches for walkways and patios, if desired. The gradational requirements are summarized on Table 3. Table 3: Gradational Requirements for ASTM No. 57. No. 8. No. 89. and Nn. 9 Sieve Size Percent Passing No. 57 No. 8 No. 89 No. 9 1 /2" 100 1" 95 to 100 1/2"25to60 100 100 3/8" 85 to 100 90 to 100 100 No. 4 0 to 10 10 to 30 20 to 55 85 to 100 No.8 0to5 OtolO 5to30 10to40 No. 16 0to5 OtolO OtolO No. 50 0to5 0to5 COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 21 of 24 8.14 Utility Trench We recommend that all utilities be bedded in clean sand to at least one foot above the top of the conduit. The bedding should be flooded in place to fill all the voids around the conduit. Imported or on-site granular material compacted to at least 90 percent relative compaction may be utilized for backfill above the bedding. The invert of subsurface utility excavations paralleling footings should be located above the zone of influence of these adjacent footings. This zone of influence is defined as the area below a 45 degree plane projected down from the nearest bottom edge of an adjacent footing. This can be accomplished by either deepening the footing, raising the invert elevation of the utility, or moving the utility or the footing away from one another. 8.15 Drainage Specific drainage patterns should be designated by the project architect or engineer. However, in general, pad water should be directed away from foundations and around the structure to the street. Roof water should be collected and conducted to a suitable discharge location via non-erodible devices. Pad water should not be allowed to pond. Vegetation adjacent to foundations should be avoided. If vegetation in these areas is desired, sealed planter boxes or drought resistant plants should be considered. Other alternative may be available, however, the intent is to reduce moisture from migrating into foundation subsoils. Irrigation should be limited to that amount necessary to sustain plant life. All drainage systems should be inspected and cleaned annually, prior to winter rains. At a very minimum, the sides of the bioretention basins should be scaled with an impervious liner. 8.16 Geotechnical Observations Structural footing excavations should be observed by a representative of this firm prior to the placement of steel and forms. All fill should be placed while a representative of the geotechnical engineering is present to observe and test. 8.17 Plan Review The grading plans have not been reviewed as part of this study. These plans should be reviewed by this office prior to initiation of construction. A copy of the foundation plans should be submitted to this office for review prior to the initiation of constructions. Additional recommendations may be necessary at that time. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 22 of 24 9. LIMITATIONS This report is presented with the provision that it is the responsibility of the owner or the owner's representative to bring the information and recommendations given herein to the attention of the project's architects and/or engineers so that they may be incorporated into the plans. If conditions encountered during construction appear to differ from those described in this report, our office should be notified so that we may consider whether modifications are needed. No responsibility for construction compliance with design concepts, specifications, or recommendations given in this report is assumed unless on-site review is performed during the course of construction. The subsurface conditions, excavation characteristics, and geologic structure described herein are based on individual exploratory excavations made on the subject property. The subsurface conditions, excavation characteristics, and geologic structures discussed should in no way be construed to reflect any variations which may occur among the exploratory excavations. Please note that fluctuations in the level of groundwater may occur due to variations in rainfall, temperature, and other factors not evident at the time measurements were made and reported herein. Coast Geotechnical assumes no responsibility for variations which may occur across the site. The conclusions and recommendations of this report apply as of the current date. In time, however, changes can occur on a property whether caused by acts of man or nature on this or adjoining properties. Additionally, changes in professional standards may be brought about by legislation or the expansion of knowledge. Consequently, the conclusions and recommendations of this report may be rendered wholly or partially invalid by event beyond our control,. This report is therefore subject to review and should not be relied upon after the passage of two years. The professional judgements presented herein are founded partly on our assessment of the technical data gathered, partly on our understanding of the proposed construction, and partly on our general experience in the geotechnical field. However, in no respect do we guarantee the outcome of the project. This study has been provided solely for the benefit of the client, and is in no way intended to benefit or extend any right or interest to any third party. This party is not to be used on other projects or extensions to this project except by agreement in writing with Coast Geotecimical. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 23 of 24 RFERENCES Blake, T. F. (2000). EQFAULT: A Computer Program for the Deterministic Estimation of Peak Acceleration using Three-Dimensional California Faults as Earthquake Sources, Version 3.0, Thomas F. Blake Computer Services and Software, Thousand Oaks, CA. California Building Standards Commission. (January 1, 2016). 2016 California Building Code, California Code of Regulations. California Emergency Management Agency, California Geological Survey, and University of Southern California. (2009). Tsunami Inundation Map for Emergency Planning: Encinitas Quadrangle, California, San Diego County, Scale 1:24,000. California Geologic Survey, (1994), Fault Activity Map of California, Map Scale 1 "=750,00'. FEMA, Flood Map Service Center https://msc.fema.gov/portallhome Kennedy, M. P., and Tan, S. S. (2008). California Geological Survey, Regional Geologic Map No. 3, 1:100,000 scale. Luptin, Stephanie, (2017). Fukuda Remodel/Addition. 2726 Morning Glory Lane, Carlsbad, California. Sahakian, V., et al. (2017). Seismic Constraints on the Architecture of the Newport-Inglewood/Rose Canyon Fault: Implications for the Length and Magnitude of Future Earthquake Ruptures. American Geophysical Union. DO!: 10.1002/20 16JB0 13467. Seed, H.B., and Whitman, R.V. (1970). Design of earth retaining structures for dynamic loads. In Proceedings of the ASCE Special Conference on Lateral Stresses, Ground Displacement and Earth Retaining Structuje, Ithaca, N.Y., pp. 103-147. COAST GEOTECHNICAL Lane Fukuda W.O. 707419 Page 24 of 24 Tan, S. S., and Giffen, D. G. (1995). Landslide Hazards in the Northern Part of the San Diego Metropolitan Area, San Diego County, California, OFR 95-04, Plate 35D. Treiman, J. A. (1984). The Rose Canyon Fault Zone: A Review and Analysis, California Division of Mines and Geology, Fault Evaluation Report 216. Wood, J.H. (1973). Earthquake-induced soil pressures on structures. Ph.D. thesis, the California Institute of Technology, Pasadena, Calif. OSHPD, U.S. Seismic Design Maps https://seismicmaps.org REGIONAL FAULT MAP SAN DIEGO COUNTY REGION Holocone fault displacement (dunng pest 11.700 yets) wthool 1t41000 ,ecool. Late Oe.tcmanj fault displacement (donng past 700.000 ycem). Ocatemary (C dl (age afferaketodt ?ce-O.r,rary (colt (older that 16reelson years) 0' fault sc00r4 recagnzed Qaiternacy dmplaoamenl ADDITIONAL FAULT SYMBOLS Bar and boll cc docerltreown We (rilatro. or apparenl) MOws eteeg (Cuit 1nftW reltrwe or apparent direct .e, Of lateral movement Arrow cc (orAl ardinales deectoc of dip. Low engis (soft (barb, on spper plate). Map is reproduced from California Geological Survey, "Fault Activity Map of California (2010)". COAST GEOTECHNCAL 5931 Sea Lion Place, Suite 109 Carlsbad, CA 92010 Project Number: 707419 Figure Number: 5 FLOOD HAZARD MAP 2726 MORNING GLORY LANE, CARLSBAD - 'S..... .F'\-r.:"1 c •ç ',(• ,. jr . Approxmate locaum based or, jaar input WIthout Bians Fad Motion 8FE) Zpft A. V A99 V and does not represent an autloritaere With RFE or Depth Y property ocation SPECIAL FLOOD PIN Regullatory Flioodway Zone AE.lo.AJA2 C) Selected Flooduap aundar 0.2% Annual Chance Flood Hazard. Areas Ota DataAvaable of 1% annual chance flood with average No Digital Data Avaab3e depth less than one foot or with drainage areas of less than one square mile MAP PANELS Unrflapped - -, Future Conditions 1% Annual Chance Flood Hazard Zcc X o ScRres Area of Miatmal Flood H5ardZx'X Area with Reduced Flood Risk due to I EffeOUceLOMRS OTHER AREAS OF Lit. See Nola. Zcc X Area of Undetermined Flood Kaurd zDqt D FLOOD HAZARD Area with Flood Risk due to Levee zwo 0 Otherwa. Protected Area OTHER AREAS ' \\Ncoast&155rr1er R Area Exerpt from the FEMAF1od Map Service Center ©COAST GEOTECHNICAL Project Number: 707419 5931 Sea Lion Place, Suite 109 Figure Number: 6 Carlsbad, CA 92010 PLAN VIEW Existing Covered Patio Column Pad IN ----- V— — — V— --- ---- ------ CROSS SECTION Existing Covered Patio oil Existing Column Pad ! Temporary 1:1 Slope Slot Cut B\ ---------1:I IN0sCI Excavate Slot Cuts A and C, 5 feet wide not to excecd 6 feet. Construct wall in Slot Cuts A and C prior to Excavating Slot Cut B. ABC SLOT CUTS EXCAVATION DETAIL COAST GEOTECHNICAL Project Number: 707419 5931 Sea Lion Place. Suite 109 Figure Number: 7 Carlsbad, CA 92010 (a) (b) ISOLATION JOINTS ----------- CONTRACTION JOINTS RE-ENTRANT CORNER RACK RE-ENTRA REINFORCEMENT NT CORNER ?V NO.3 BARS PLACED / MID-HEIGHT IN SLAB NO SCAI.E I. Isolation Joints around the columns should be either circular as shown in (a) or diamond shaped as shown in (b). If no isolation joints are used around columns, or if the corners of the isolation joints do not meet the contraction joints, radial cracking as shown in (c) may occur (reference AC!). In order to control cracking at the re-entrant corners (+1- 270 degree corners), provide reinforcement as shown in (c). Re-entrant corner reinforcement shown herein is herein is provided as a general guideline only and is subject to verification and changes by the project architect and I or structural engineer based upon slab geometry, location, and other engineering and construction factors. TYPICAL ISOLATION JOINTS AND RE-ENTRANT CORNER REINFORCEMENT COAST GEOTWUNICAL Project Number: 707419 5931 Sea Lion Place, Suite 109 Carlsbad, CA 92010 Figure Number: 8 Finish Grade /• - j2min. Compacted Fill Geo-Synthetic - Drainage Panels Waterproofing Membrane Behind Retaining Wall Para Seal - Water Stop : .,Concrete Subgrade Schedule 40 PVC Pipe Perforated Drain Sloped Leading to Positive Schedule 40 PVC Pipe Gravity Outlet or Solid Drain Connected to Miridrain Collection Drain Controlled Drainage Device BASEMENT WALL DRAINAGE DETAIL COAST GEOTECHNICAL Project Number: 707419 5931 Sea Lion Place, Suite Figure Number: 9 Carlsbad, CA 92010 TYPICAL PERMEABLE PAVER DETAIL Na 8 AGGREGATES I IN OPENINGS PER CURB / MANUFACTURER SPECS. _____/ PERMEABLE PAERS I 1 r(TRAFFIC.RAWo) 111IGI( CO.VLRETE PA WRS TRAFFIC LOADING 6 CONCRETE EDGE RESTRAIN I 2" BEDDING COURSE (NO. 8 AGGREGATE ON PER MANUFACTURER SPECS) THICK OPEN GRADED 8A , MIN. 5 0 PER HOUR INF7L IRA liON RA 1E (No 57 STONE - 3/4 MAX.) AT 3J4 GRAVEL '— OPEN GRADED - - BA (No. 57 STONE-3/4 MAX.) 5rAL SUUGRADE UPPER 120 AT 95% CCIPAC1I0At (ASThI 01557) Schematic And Conceptual Only No—Scale 4" PERFORATED UNDERDRAIN 501. 40 PVC. CONNECT TO PERFORATED PIPES UNDER THE BIORE1EN71ON AREAS. ()COAST GEOTECHNICAL Project Number: 707419 Cadsbad, CA 92010 5931 Sea Lion Place, Suite 109 Figure Number: 10 APPENDIX Logs of Boring / Test Pits APPENDIX Laboratory Test Results Earth deposits encountered in our exploratory boring and test pit excavations were closely examined and sampled for subsequent laboratory testing. The laboratory tests were performed in accordance with the generally accepted American Society for Testing and Materials (ASTM) test methods or suggested procedures. Based upon our borings and field exposures, site soils have been grouped into the following soil types: Soil Type Description I I i I Orangish medium to dark brown, silty sand I The following tests were conducted in support of this investigation: 1. Grain Size Analysis: A grain size analysis was performed on a representative sample of Soil Type 1. The test results are presented below, and graphically illustrated as attached on Figure B 1. I Sieve Size %" J V" I#4 #10 1 #20 I #40 #100 #200 Location Soil Type 1 Percent Passing B-I @4-5' 1 100.0T-106-0.06-1 100.0 I 99.7 I 98.6 I 74.3 I 34.6 I 26.9 2. Sedimentation Test: A sedimentation test was performed on a representative sample of Soil Type 1. The test results are presented below, and graphically illustrated as attached on Figure B I. Grain Size (mm) 0.07T--0.05 0.035 1 0.015 1 0.01 10.007 J 0.0035 0.0015 Location Soil Type Percent Soil Remaining B-I @4-5' 1 26.6 I 23.2 J 23.0 I 19.0 I 17.1 I 15.9 j 13.7 I 9.9 3. Maximum Dry Density and Optimum Moisture Content: The maximum dry density and optimum moisture content of Soil Type 1 were determined in accordance with ASTM D-1557. The results are presented in below. H Location -I Soil I Maximum Dry I Optimum Moisture Type I Density (Yin-pd) I Content (wopt-%) Ii B-1 @ -5' 1 1 I 134.0 I 10.3 4. Unit Weight & Moisture Content Tests: In-place &y density and moisture content of collected representative soil samples were determined from relatively undisturbed ring samples using the ring density tests, and Water Content of Soil and Rock by Mass test method in accordance with ASTM 132216. The test results are presented in below and tabulated on the boring logs in Appendix A. Sample Soil Field Moisture Field Dry Max. Dry In-Place Degree of Location Type Content Density Density Relative Saturation (Yd-pcf) (Ym-pet) Compaction S(%) B-I @2' 1 9.5 117.0 134.0 87.3 63.7 B-i @' 1 9.6 114.6 134.0 85.5 59.9 B-1 @ 8' 1 9.6 113.9 134.0 85.0 58.7 B-i @11' 1 9.1 113.9 134.0 85.0 55.7 TP-1 @2' 1 7.0 115.2 134.0 86.0 44.6 TP-2 @2' 1 4.4 116.1 134.0 86.6 68.6 Assumptions and Relationships: In-place Relative Compaction = (Yd + Ym) Xl 00 Gs=2.70 e = (Gs Yo) - Yd) - I - S=(w Gs) +e 5. Expansion Index Test: One expansion index (El) test was performed on a representative sample of Soil Type 1 in accordance with the ASTM D4829. The test results are presented below. Sample Location B-i @4-5' Soil 1.11 I • I Degree of Final I Initial Dry 1-11 I I Saturation Density I Molded Type I I I 7.4 I 47.2 I 13.2 I 118.4 Measured 50% El I El Saturation 0 I 0 (o) = moisture content in percent E150 = Elmeas - (50 - Smeas) ((65 + Elmeas) + (220 - Smeas)) Expansion Index (El) Expansion Potential 0-20 Very Low 21-50 Low 51-90 Medium 91-130 High )130 VervHih Direct Shear Test: Two direct shear tests were performed on representative samples of Soil Type 1 in accordance with ASTM D3080. The prepared specimens were soaked overnight, loaded with normal loads of 1, 2, and 3 kips per square foot respectively, and sheared to failure in an undrained condition. The test results are presented below and graphically illustrated as attached on Figures B2 and B3. Sample Sample Unit Angle of Apparent Location Soil Type Condition Weight mt. Fric. Cohesion (Yw-pcl) (4-De.) (c-psf) B-1 ® 8' 1 In-Place 115.6 28.1 170 TP-1 @Z_ 1 In-Place 117.5 31.4 40 ji Consolidation Test: One consolidation test was performed on a representative sample of Soil Type I in accordance with ASTM D2435. The prepared specimen was soaked overnight, loaded to weights of 0.5, 1, 2, 4, 8, and 16 kips per square foot and unloaded to weights of 4, 1, and 0.5 kips per square foot, respectively. The test result is graphically illustrated as attached on Figure B3. S. pH and Resistivity Test: pH and resistivity of a. representative sample of Soil Type 1 was determined using "Method for Estimating the Service Life of Steel Culverts," in accordance with the California Test Method (CTM) 643. The test result is tabulated below. Sulfate Test: A sulfate test was performed on a representative sample of Soil Type I in accordance with the California Test Method (CTM) 417. The test result is presented below. Chloride Test: A chloride test was performed on a representative sample of Soil Type 1 in accordance with the California Test Method (CTM) 422. The test result is presented below. Sample Location J Soil Type Amount of Water Soluble Chloride In Soil (% by Weight) Ii B-1 @4-5' 1 1 I 0.019 APPENDIX Seismic Design Response Parameters APPENDIX Grading Guidelines Grading Guidelines Grading should be performed to at least the minimum requirements of the local governing agencies, the California Building Code,-2016, the geotechnical report and the guidelines presented below. All of the guidelines may not apply to a specific site and additional recommendations may be necessary during the grading phase. Site Clearing Trees, dense vegetation, and other deleterious materials should be removed from the site. Non-organic debris or concrete may be placed in deeper fill areas under direction of the Soils engineer. Subdrainage During grading, the Geologist and Soils Engineer should evaluate the necessity of placing additional drains. All subdrainage systems should be observed by the Geologist and Soils Engineer during construction and prior to covering with compacted fill. Consideration should be given to having subdrains located by the project surveyors. Outlets should be located and protected. Treatment ofExisting Ground All heavy vegetation, rubbish and other deleterious materials should be disposed of off site. All surficial deposits including alluvium and colluvium should be removed unless otherwise indicated in the text of this report. Groundwater existing in the 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. Fill Placement Most site soil and bedrock may be reused for compacted fill; however, some special processing or handling may be required (see report). Highly organic or contaminated soil should not be used for compacted fill. Material used in the compacting process should be evenly spread, moisture conditioned, processed, and compacted in thin lifts not to exceed six inches in thickness to obtain a uniformly dense layer. The fill should be placed and compacted on a horizontal plane, unless otherwise found acceptable by the Soils Engineer. If the moisture content or relative density varies from that acceptable to the Soils engineer, the Contractor should rework the fill until it is in accordance with the following: 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. Each six inch layer should be compacted to at least 90 percent of the maximum density in compliance with the testing method specified by the controlling governmental agency. In this case, the testing method is ASTM Test Designation D-1557-91. Side-hill fills should have a minimum equipment-width key at their toe excavated through all surficial soil and into competent material (see report) and tilted back into the hill. As the fill is elevated, it should be benched through surficial deposits and into competent bedrock or other material deemed suitable by the Soils Engineer. Rock fragments less than six inches in diameter may be utilized in the fill, provided: They are not placed in concentrated pockets. There is a sufficient percentage of fine-grained material to surround the rocks. The distribution of the rocks is supervised by the Soils Engineer. Rocks greater than six inches in diameter should be taken off site, or placed in accordance with the recommendations of the Soils Engineer in areas designated as suitable for rock disposal. In clay soil large chunks or blocks are common; if in excess of six (6) inches minimum dimension then they are considered as oversized. Sheepsfoot compactors or other suitable methods should be used to break the up blocks. The Contractor should be required to 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. 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 approximately every 4 feet vertically as the slope is built. 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. In addition, 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 the slope should be performed after construction is complete. Each day the Contractor should receive a copy of the Soils Engineer's "Daily Field Engineering Report" which would indicate the results of field density tests that day. Fill over cut slopes should be constructed in the following manner: All surficial soils and weathered rock materials should be removed at the cut-fill interface. A key at least I equipment width wide (see report) and tipped at least 1 foot into slope should be excavated into competent materials and observed by the Soils Engineer or his representative. The cut portion of the slope should be constructed 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. Transition lots (cut and fill) and lots above stabilization fills should be capped with a four foot thick compacted fill blanket (or as indicated in the report). Cut pads should be observed by the Geologist 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. Exploratory backhoe or dozer trenches still remaining after site removal should be excavated and filled with compacted fill if they can be located. Grading Observation and Testing Observation of the fill placement should be provided by the Soils Engineer during the progress of grading. In general, density tests would be made at intervals not exceeding two feet of fill height or every 1,000 cubic yards of fill placed. This criteria will vary depending on soil conditions and the size of the fill. In any event, an adequate number of field density tests shouldbe made to evaluate if the required compaction and moisture content is generally being obtained. Density tests may be made on the surface material to receive fill, as required by the Soils Engineer. Cleanouts, processed ground to receive fill, key excavations, subdrains and rock disposal should be observed by the Soils Engineer prior to placing any fill. It will be the Contractor's responsibility to notify the Soils Engineer when such areas are ready for observation. A Geologist should observe subdrain construction. A Geologist should observe benching prior to and during placement of fill. Utility Trench Backfill Utility trench backfill should be placed to the following standards: Ninety percent of the laboratory standard if native material is used as backfill. As an alternative, clean sand may be utilized and flooded into place. No specific relative compaction would be required; however, observation, probing, and if deemed necessary, testing may be required. Exterior trenches, paralleling a footing and extending below a 1:1 plane projected from the outside bottom edge of the footing, should be compacted to 90 percent of the laboratory standard. Sand backfill, unless it is similar to the mplace fill, should not be allowed in these trench-backfill areas. Density testing along with probing should be accomplished to verify the desired results.