PRELIMINARY SOIL AND GEOLOGIC INVESTIGATION REPORT PROPOSED SINGLE-FAMILY HOME REMODEL 26871 HIGHWOOD AVENUE LAGUNA HILLS, CALIFORNIA Prepared for: FAM VANS 10870 Kalama River Avenue Fountain Valley, California 92708 Prepared by GeoMat Testing Laboratories, Inc. 9980 Indiana Avenue Suite 14 Riverside, California 92503 Project No. 19097-01 June 11, 2019
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PRELIMINARY SOIL AND GEOLOGIC INVESTIGATION REPORT
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PRELIMINARY SOIL AND GEOLOGIC INVESTIGATION REPORT
PROPOSED SINGLE-FAMILY HOME REMODEL 26871 HIGHWOOD AVENUE LAGUNA HILLS, CALIFORNIA Prepared for: FAM VANS 10870 Kalama River Avenue Fountain Valley, California 92708 Prepared by
GeoMat Testing Laboratories, Inc. 9980 Indiana Avenue Suite 14 Riverside, California 92503 Project No. 19097-01 June 11, 2019
9980 Indiana Avenue ● Suite 14 ● Riverside ● California ● 92503 ● Phone (951) 688-5400 ● Fax (951) 688-5200
10870 Kalama River Avenue Fountain Valley, California 92708
SUBJECT: Preliminary Geotechnical Investigation Report, Proposed Single-Family Home Remodel at
26871 Highwood Avenue, Laguna Hills, California In accordance with your authorization, GeoMat Testing Laboratories, Inc. (GeoMat) has performed a preliminary geotechnical investigation at the subject site. The accompanying report presents a summary of our findings, conclusions, recommendations, and limitation of work for the proposed single-family home remodel. The primary purpose of this investigation and report is to provide an evaluation of the existing geotechnical conditions at the site as they relate to the design and construction of the proposed development. More specifically, this investigation was to address geotechnical issues for the preliminary design of the structure’s foundation. If you should have any questions regarding this report, please do not hesitate to call our office. We appreciate this opportunity to be of service. Submitted for GeoMat Testing Laboratories, Inc. Haytham Nabilsi, GE 2375 Eirik Haenschke, CEG 1597 Project Engineer Engineering Geologist Distribution: (3) Addressee
1.1 Scope of Work ..................................................................................................................................... 1 1.2 Existing Site Conditions ...................................................................................................................... 1 1.3 Proposed Development ...................................................................................................................... 1
2.0 RECORDS OF PREVIOUS REPORTS ..........................................................Error! Bookmark not defined.
3.0 SUMMARY OF GEOTECHNICAL CONDITIONS ....................................................................................... 2
3.1 Field Work ........................................................................................................................................... 2 3.2 Subsurface Findings ........................................................................................................................... 2
9.0 LIMITATION OF INVESTIGATION ............................................................................................................ 15
ATTACHMENTS: Exhibit 1 Site Location Map Figure 1 Regional Geologic Map Figure 2 Regional Fault Map Figure 3 Seismic Hazard Zones Map Plate 1 Exploratory Boring Location Map Plate 2 Geologic Cross Section A-A’ and B-B’ Plate 3 Retaining Wall Drainage Detail APPENDIX: Appendix A References Appendix B Geotechnical Boring Logs Appendix C Laboratory Test Results Appendix D 2016 CBC Seismic Design Parameters Appendix E Slope Maintenance Guidelines Appendix F Slope Stability Analysis
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1.0 INTRODUCTION
1.1 Scope of Work
• Review soils, seismic, groundwater data, and maps in our files.
• Exploration of the site at accessible location.
• Field geologist for logging and soil sampling.
• Laboratory testing of selected soil samples.
• Preparation of a geotechnical investigation report to include: allowable soil bearing value, foundation recommendations, slab-on-grade, earth pressures, Site Class, CBC seismic design parameters, and cement type.
1.2 Existing Site Conditions The subject site is located at the terminus of Highwood Avenue, in the City of Laguna Hills, California. Access on site is from Highwood Avenue which is a paved road with rolled curb and gutter improvements. The geographical relationship of the site and surrounding vicinity is shown on the Site Location Map, Exhibit 1. An existing single family home is located on the flat portion of the lot. Based on the provided site plan dated November 28, 2018 and prepared by KF Kessler of Irvine, California, the average elevation of the building pad is 395. The lot gently descends down at a gradient of 3H:1V toward the west and northwest and the slope becomes flatter thereafter. In general, the site is fully developed. 1.3 Proposed Development We understand that the existing home is proposed for a remodel. We also understand that the existing concrete foundation and slab will remain. Possible additional footings and/or slabs may be added. We have not been provided with specific structural details. We anticipate however, that continuous wall loads will not exceed 2500 pounds per linear foot and isolated column loads of up to 25 kips.
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2.0 SUMMARY OF GEOTECHNICAL CONDITIONS
2.1 Field Work On May 21, 2019 four exploratory test pits were excavated on the site to observe the nature and condition of the onsite soils and bedrock, and to retrieve undisturbed and bulk samples for laboratory testing. The test pits ranged in depth from approximately 3’6” to 5’ and were logged in the field by our certified engineering geologist. Detailed logs of the exploratory test pits are presented as Plates B-1 through B-4 in Appendix B of this report. The earth materials encountered within the exploratory test pits are described generally in the following sections. 2.2 Subsurface Findings 2.2.1 Fill Artificial (man-placed) fill soils were encountered beneath the surface to depths of 1- to 2-feet in test pits TP-1, TP-3 and TP-4. The fill consisted of clayey sand to silty sand with rock fragments, was firm to medium dense in consistency, and moist. 2.2.2 Colluvium Natural colluvial soils were encountered mantling the hillside, beneath the fill and/or overlying bedrock in all test pits excavated at the site. The colluvium ranged from approximately 1- to 2-feet in thickness and consisted of dark brown fat clay with sand and scattered small rock fragments. The colluvium was generally stiff in consistency, and moist. Natural soils overlying bedrock in TP-3 consisted of 1-foot of tan fine sand with clasts of gray siltstone, which is thought to represent a remnant of sandy terrace deposit at that location. 2.2.3 Bedrock Natural bedrock consisting of gray sandy siltstone and clayey siltstone was encountered in the exploratory test pits to the total depths explored at each location. The bedrock was moderately well to well indurated and vaguely bedded. Bedding structure within the bedrock on-site is variable, ranging from horizontal to dipping 10 northwesterly in TP-1. The distribution of soil and bedrock, and bedding structure in the subsurface are illustrated on Geologic Cross Sections A-A’ and B-B’, included as Plate 2. More detailed descriptions of the earth materials are presented in the Test Pit Logs in Appendix B. 2.3 Soil Type In accordance with OSHA, the onsite soil may be classified as follows:
Colluvium: Soil Type “B”. Bedrock: Soil Type “A”.
2.4 Groundwater Groundwater study is not within the scope of this work. Groundwater was not encountered in any of the exploratory pits conducted onsite up to 5 feet below ground surface, on the slope.
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The California Department of Conservation, Seismic Hazard Report for San Juan Capistrano Quadrangle has no historic groundwater data in the immediate vicinity of the site. The quadrangle, however, shows ground water at 20 feet below ground surface (approximate elevation 244) along Oso Parkway, north of the subject lot. The potential for rain or irrigation water locally seeping through from adjacent elevated areas cannot be precluded. Our experience indicates that surface or near-surface groundwater conditions can develop in areas where groundwater conditions did not exist prior to site development, especially in areas where a substantial increase in surface water infiltration results from landscape irrigation. In addition, changes in local or regional water and management patterns, or both, can significantly raise the water table or create zones of perched water over bedrock or native soil. We therefore recommend that landscape irrigation be kept to the minimum necessary to maintain plant vigor and any leaking pipes/sprinklers, etc. should be promptly repaired. The depth to the groundwater may fluctuate with seasonal changes and from one year to the next. We have no way of predicting future groundwater levels or perched water due to increase in surface water infiltration from rainfall or from landscape irrigation. Subdrains, horizontal drains, toe drains, French drains, heel drains or other devices may be recommended in future for graded areas that exhibit nuisance water seepage, past evidence for shallow water, or areas with a potential for future shallow/surface water. 2.5 Laboratory Testing Laboratory tests were performed on selected soil samples. The tests consisted primarily of in-place densities, moisture content, Atterberg limits, direct shear, residual direct shear, expansion index, and sulfate. The soil classifications are in conformance with the Unified Soil Classifications System (USCS), as outlined in the Classification and Symbols Chart (Appendix B). A summary of our laboratory testing, ASTM designation, and graphical presentation of test results is presented in Appendix C. 2.5.1 Moisture Content and Dry Density The field moisture contents, as a percentage of the dry weight of the soils, were determined by weighing samples before and after oven drying. The dry density, in pounds per cubic foot (pcf), was also determined for all relatively undisturbed ring samples collected. These analyses were performed in accordance with ASTM Methods D2216 and D2937. The results of these determinations are shown on the boring logs in Appendix B. 2.5.2 Atterberg Limits Atterberg Limits was performed on a representative soil sample to determine the plasticity of fine-grained soils and to assist in their classification. The test procedures were performed in accordance with ASTM D4318. 2.5.3 Direct Shear Direct shear tests were performed on selected relatively undisturbed ring samples in accordance with ASTM Method D3080. The sample was soaked prior to testing. A different normal stress was applied vertically to each soil sample ring, which was then sheared in a horizontal direction. A new ring was used for each load. Each shear test was performed on a single ring with no multiple re-shearing. 2.5.4 Residual Direct Shear Residual direct shear tests were performed on selected relatively undisturbed ring samples in accordance with ASTM-D3080, CGS Special Publication 117A, and Blake et. al. (2002). The sample was soaked prior to testing. A different normal stress was applied vertically to each soil sample ring, which was then sheared in a horizontal direction.
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A new ring was used for each load. Each shear test was performed on a single ring with multiple cycles of shearing until the last two cycles with the same displacement curve results. The sample was manually returned to its original position at the end of each cycle of shearing. Ring samples where large gravels were exposed at the surface were not used for the shear tests. For ring samples containing fine gravel, if the fine gravel pieces were visible at the surfaces of the sample during sample preparation, the gravel was removed and patched with finer soil to achieve smooth and flat conditions of the sample surfaces before placing the sample into the test apparatus. Fine gravels inside a sample that were not visible during sample preparation were left in place. The resulting shear strength for the corresponding normal stress was measured at maximum shear stress, at a shear strain of approximately twenty percent of the first shearing, and at the end of the last re-shearing. 2.5.5 Expansive Soil Characteristics Based on the laboratory plasticity index testing, the onsite soils are expected to have a high expansion potential (EI<130), as defined in Table 18-I-B of the 2001 CBC. This would require verification subsequent to completion of new footing excavations. 2.5.6 Soluble Sulfate Content Laboratory testing conducted for a soil sample showed that water soluble sulfate content was 0.03 percent (Negligible sulfate exposure risk). We recommend Type II cement for all concrete work in contact with soil. Ferrous metal pipes should be protected from potential corrosion by bituminous coating, etc. We recommend that all utility pipes be nonmetallic and/or corrosion resistant. Recommendations should be verified by soluble sulfate and corrosion testing of soil samples obtained from specific locations at the completion of grading.
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3.0 GEOLOGIC FINDINGS
3.1 Regional Geology The subject site consists of a residential lot adjoining the west edge of the Highwood Circle cul-de-sac. The lot contains a relatively level building pad near street grade, with gentle natural slopes descending westerly and southwesterly from the residence pad level at gradients of approximately 3:1 or less. Published regional geologic maps of the area indicate the subject site is underlain by siltstone bedrock assigned to the Capistrano Formation of Pliocene/Miocene geologic age. Mapped bedding structure within the bedrock is variably oriented, ranging from horizontal to approximately 10° in the site vicinity (Morton, 2006). The approximate site location is indicated on the Regional Geology Map, Figure 1. 3.2 Regional Faulting and Seismic Hazards There are no mapped active or potentially active faults with surface expression that trend through or are adjacent to the subject property, according to those references cited herein. The site does not lie within a designated Alquist-Priolo Earthquake Fault Zone (CDMG, 2000). According to the Fault Activity Map of California (2010), the site lies approximately 8 miles northeast of the Newport-Inglewood fault zone, capable of producing an M6.9 earthquake, and approximately 16 miles southwest of the Elsinore fault, capable of producing an M6.8-M7 earthquake (see Figure 2). Based on the CGS Probabilistic Seismic Hazards Ground Motion Interpolator (2008), the peak ground acceleration for firm rock conditions at the site is reported to be 0.301g with a 10% probability of being exceeded in 50 years. The estimated ground shaking is derived from statewide seismic hazard evaluation released cooperatively by the California Division of Mines and Geology and United States Geological Survey based on long-term slip rate, maximum earthquake magnitude and rupture geometry, and historical seismicity associated with known fault sources in the site vicinity. The subject site, as is the case with most of the tectonically-active Southern California area, will be periodically subject to moderate to intense earthquake-induced ground shaking from nearby faults. Significant damage can occur to the site and structural improvements during a strong seismic event. Neither the location nor magnitude of earthquakes can accurately be predicted at this time. 3.3 Secondary Seismic Hazards According to the Seismic Hazard Zones Map (see Figure 3) published by the State of California, Division of Mines and Geology, San Juan Capistrano Quadrangle (2001), portions of the gentle natural slopes descending westerly and southwesterly from the Highwood Circle cul-de-sac are indicated to be potentially susceptible to seismically-induced slope failure. The subject site is not indicated to lie within a zone of potential seismic liquefaction hazard. 3.3.1 Liquefaction: Due to the presence of bedrock underlying all portions of the subject site at shallow depth, and depth to groundwater, earthquake induced liquefaction and consolidation are not likely to occur on the site. 3.3.1.1 Seismic Settlement: The site is not prone to liquefaction. Therefore, the potential for liquefaction associated ground deformation (seismic settlement and differential compaction) beneath the site is considered to be unlikely.
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3.3.2 Slope Stability: The proposed foundations within the existing slope will be recommended in the following sections to be established in competent bedrock with appropriate setbacks. Drainage control measures recommended in this report and by the project civil engineer should be implemented during site development. 3.3.2.1 Seismic Demand A seismic coefficient (Keq) of 0.20g was utilized in our analysis and was derived based on a maximum allowable displacement of 5 cm, a computed PGAM of 0.557g, a moment magnitude of 6.9, and a distance to the ground motion source of 12 km. 3.3.2.2 Surficial Stability Surficial stability was analyzed at the steepest location of the existing slope assuming infinite slope with seepage parallel to the slope surface and consistent subsoil profile. The failure plane for this case is parallel to the surface of slope and the limit equilibrium method can be applied readily. Shear strength of the onsite soil and was tested in the laboratory. The analysis assumes the steepest point on the slope is 29 degrees, based on the provided topographic plan (refer to Plate 1). The results show a safety factor greater than the required minimum of 2.2. The result is as follows:
Considering the shear strength of native soil and the slope inclination, seasonal local surficial sloughing cannot be entirely precluded and should be considered by the project design team. Permanent devices should be designed by the project civil engineer such as but not limited to wall free board, “V” ditches, benches, etc., to minimize and contain any remote pop-outs. In addition, to minimize the potential for surficial sloughing the slope should be maintained with appropriate deep root vegetation and ground cover. As a minimum the slope maintenance guidelines presented in Appendix E should be followed. 3.3.2.3 Global Stability Analysis Global stability analysis was performed to evaluate the probable static and dynamic gross stability of the existing slope configuration, see cross sections A-A’ on Plate 2. The analyses project the slope’s general inclination at about 3.35H:1V. The analyses utilize the simplified method of slices by Bishop. The residual shear strength parameters used in the software analysis were based on laboratory test results of relatively undisturbed samples obtained from the onsite soil. The residual shear strength was applied along the entire slope (anisotropic). The results of the stability analyses for homogenous slope material indicated that the slope configuration will be adequate with a safety factor of over 1.5 in static condition and 1.0 in dynamic condition. Continuing stability of the slope will greatly depend on controlling the water, proper planting and maintaining the drainage for proper functioning. Slope stability analysis is presented in Appendix F. Summary of test results are in the following table:
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Global Stability Safety Factors
Case Static Condition Dynamic Condition
Global Circular Plane 2.17 1.34
Drainage control measures recommended in this report and the project civil engineer should be implemented during site development. 3.3.3 Tsunamis and Seiches The setting is inland, and no large bodies of water are located immediately up-gradient of the site, therefore, the potential of tsunamis or seiches affecting the site is considered low. 3.3.4 Subsidence The site is not in an area of known subsidence, associated with petroleum or groundwater extraction. 3.4 Site Class It is our opinion that structures should be designed in accordance with the current seismic building code as determined by the structural engineer. Considering the Spectral Response Acceleration at short period SDS > 0.50g (CBC Table 1613.5.6(1), and the Spectral Response Acceleration at one second period SD1 >0.20g (CBC Table 1613.5.6(2), the subject site is located in an estimated Site Class “D” as outlined in CBC Table 1613.5.2. 3.5 Ground Motion and Seismic Design Parameters: The peak ground acceleration (PGA) and 2016 CBC seismic design parameters are presented in Appendix D.
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4.0 CONCLUSIONS
• Active or potentially active faults are not known to exist on or in the immediate vicinity of the site.
• The site is located in a region of generally high seismicity, as is all of southern California. During its design life, the site is expected to experience strong ground motions from earthquakes on regional and/or local causative faults. Therefore, typical structural design mitigations should be considered by the structural engineer.
• The use of shallow foundation is considered feasible for the proposed development.
• Based on visual observations and plasticity index test, onsite soil is expected to be high in expansion potential (EI<130). This should be verified following footing excavation.
• No groundwater and/or seepage was encountered during our subsurface investigation.
• Potential for rain or irrigation water moving through from adjacent and elevated areas cannot be precluded. Our experience indicates that surface or near-surface groundwater conditions can develop in areas where groundwater conditions did not exist prior to site excavation, especially in areas where a substantial increase in surface water infiltration results from landscape irrigation. Since groundwater may fluctuate throughout the year, we recommend the contractor verify groundwater conditions and evaluate dewatering requirements prior and during to construction.
• Based on the results of our geotechnical investigation of the site, it is our opinion that the proposed improvements are feasible from a geotechnical standpoint, provided the following recommendations are incorporated into the project plans and specifications.
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5.0 RECOMMENDATIONS
5.1 Site Preparation for any New Foundation This report assumes that existing foundation and slabs will remain in place with possible additional footings and or slabs on grade. For any proposed (additional) foundation, debris, abandoned utility lines, irrigation appurtenances, underground structures, deleterious materials, etc., should be removed from the new footing area to expose competent ground. 5.2 Temporary Excavations All excavations must comply with applicable local, state, and federal safety regulations including the current OSHA Excavation and Trench Safety Standards. Construction site safety generally is the sole responsibility of the Contractor, who should also be solely responsible for the means, methods, and sequencing of construction operations. 5.2.1 Excavation Characteristics The upper alluvial soil onsite generally consists of medium firm to firm silt with sand which is not expected to exhibit difficult excavating resistance for typical excavating equipment in good working condition. 5.2.2 Safe Vertical Cut Temporary un-surcharged excavations of 4 feet high may be made at a vertical gradient for short periods of time. Temporary un-surcharged excavations greater than 4 feet may be trimmed back at 1H:1V gradients. Exposed condition during construction should be verified by the project geotechnical engineer. No excavations should take place without the direct supervision of the project geotechnical engineer. All applicable requirements of the California Construction and general Industry Safety Orders, the Occupational Safety and Health Act, and current amendments, and the Construction safety Act should be met. Cuts should be observed during excavation by the project’s geotechnical consultant. If potentially unstable soil conditions are encountered, modifications of slope ratios for temporary cuts may be required. 5.2.3 Excavation Setbacks No excavations should be conducted, without special considerations, along property lines, public right-of-way, or existing foundations, where the excavation depth will encroach within the “zone of influence”. The “zone of influence” of the existing footings, property lines, or public right-of-way may be assumed to be below a 45-degree line projected down from the bottom edge of the footing, property line, or right-of-way. 5.2.4 Precaution for Excavations The Contractor should be aware that unsupported excavation depths should in no case exceed those specified in local, state, and/or federal safety regulations (e.g., OSHA Health and Safety Standards for Excavations, 29 CFR Part 1926, or successor regulations). Such regulations are strictly enforced and, if they are not followed, the Owner, Contractor, and/or earthwork and utility subcontractors could be liable for substantial penalties. The contractor’s “responsible person”, as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations as part of the contractor’s safety procedures.
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5.3 Tentative Foundation Recommendations 5.3.1 Foundation Setback All buildings and structures placed on slopes steeper than 3H:1V shall be in accordance with the building Code. The building code calls for a minimum foundation setback of H/3 (H being equal to the total height of the slope) but need not be greater than 40 feet. 5.3.2 Soil Bearing Value The use of shallow spread footings founded in competent soil is feasible. A maximum allowable bearing value of 2200 psf is recommended for the following footing system.
• Depth of continuous and pad footings below natural and finish grade and below slab on grade should be at least 24-inches. Pad footings should measure at least 24”B x 24”W square.
• Footing reinforcement should be determined by the structural engineer; however, minimum reinforcement should be at least two No. 4 reinforcing bars, top and bottom.
• The above recommended soil bearing value may be increased by one third for temporary (wind or seismic) loads.
Resistance to lateral footing will be provided by passive earth pressure and base friction. For footings bearing against firm native material, passive earth pressure may be considered to be developed at a rate of 190 psf per foot of depth to a maximum of 2000 psf. Base friction may be computed at 0.30 times the normal load. If passive earth pressure and friction are combined to provide required resistance to lateral forces, the value of the passive pressure should be reduced to two-thirds the value. Foundation design comes under the purview of the structural engineer. The above recommendations should not preclude more restrictive structural requirements. The structural engineer should determine the actual footing sizes and reinforcement to resist vertical, horizontal, and uplift forces under static and seismic conditions. Reinforcement and size recommendations presented in this report are considered the minimum necessary for the soil conditions present at foundation level and are not intended to supersede the design of the project structural engineer or criteria of the governing agencies for the project. 5.3.3 Total Settlement Onsite soils below the foundation depth have relatively high strengths and will not be subject to significant stress increases from foundations of a new structure. Therefore, estimated total long-term static and seismic settlement between similarly loaded adjacent foundation systems should not exceed 1-inch. The structures should be designed to tolerate a differential settlement on the order of 1/2-inch 5.3.4 Underpinning Foundation should be underpinned if any excavation along existing foundation or extending below existing foundation level is proposed. Affected footings, should be underpinned bearing on suitable soil by a minimum 2 feet by 2 feet by 3 feet deep concrete pads placed at 6 feet on center. As an alternate, it may also be feasible to provide underpinning using a system of bracketed soldier beams, slant-augered pile, helical anchors, or mini-piles. As in the case for concrete pier underpinning, the soldier beam pile system should also bear on suitable foundation material. The consistency of the onsite material is expected to increase with depth and expected to have sufficient density at 5 feet below ground surface.
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5.4 Retaining Walls The following lateral earth pressures and soil parameters, in conjunction with the allowable bearing capacities provided in the “Tentative Foundation Recommendations” section of this report may be used for the design of retaining walls with free draining compacted backfills. If passive earth pressure and friction are combined to provide required resistance to lateral forces, the value of the passive pressure should be reduced to two-thirds the following recommendations.
Passive Case (Drained) Level Backfill 190 to a maximum of 2000
Horizontal Coefficient of Friction 0.30
Unit Soil Weight 120 pcf
The lateral earth pressures were calculated using residual shear strength values of the onsite bedrock material. 5.4.1 Seismic Earth Pressure Retaining walls greater than 6 feet in height (stem wall plus footing) will need to be designed for additional seismic forces as well. The seismic load due to lateral earth pressure may be defined in accordance with NAVFAC. Dynamic Component, Yielding Condition PAE = 3/8(kh)ƳH2 = 9H2
PAE is in lb/linear foot of wall Kh is equal to 35%PGAM for cantilever and 75%PGAM for restrained condition H is height of wall in feet Ƴ is equal to the unit weight of the backfill in pcf, 120 pcf The resultant dynamic force acts at a distance of 0.6H of the inverted pressure triangle. PGAM can be found in Appendix D. Dynamic forces are short term loading. A one-third increase in bearing pressure and passive resistance may be allowed for dynamic analysis. 5.4.2 Retaining Wall Waterproofing The backfilled side of all retaining walls should be coated with an approved waterproofing compound or covered with a similar material to inhibit migration of moisture through the walls. It is recommended that the waterproofing system should be inspected and approved by the project civil engineer. The use of a water-stop should be considered for all concrete joints. We recommend contacting a waterproofing professional/consultant for specific recommendations for placement, sealing and protection of below grade walls. 5.4.3 Retaining Wall Drainage The above tabulated earth pressures assume that sufficient drainage will be provided behind the walls to prevent the build-up of hydrostatic pressures from surface and subsurface water infiltration. Back-cut distance for conventional retaining walls should be at least 18 inches to facilitate compaction. We recommend drainage for retaining walls to be provided in accordance with Plate 3 of this report. The backdrain pipe should be connected to a system of closed pipe(s) (non-perforated) that lead to the storm runoff discharge facilities. Retaining wall backdrain must be observed by GeoMat Testing Laboratories prior to wall backfill.
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New retaining walls on slopes should be provided with concrete swale to capture slough. 5.4.4 Retaining Wall Backfill All retaining wall backfill must be compacted to at least 90 percent relative compaction (ASTM D-1557), utilizing equipment that will not damage the wall. Maximum precautions should be taken when placing drainage materials and during backfilling. Onsite soils may be used as backfill. 5.5 Slabs-on-Grade Slabs-on-grade should be placed on at least 12-inches of prepared ground, compacted to a minimum of 90 percent relative compaction. Slabs-on-grade should be at least 5-inches thick and should be reinforced with at least No 4 bars at 12-inches on-center both ways, properly centered in mid thickness of slabs. Slabs-on-grade should be provided with a 15-mil Visqueen moisture barrier underlain by four inches of clean sand as indicated in 2016 Cal Green Residential Code. Slab-on-grade thickness and reinforcement should be evaluated by the structural engineer and designed in compliance with applicable codes. Excess soils generated from foundation excavations should not be placed on any building pads without proper moisture and compaction. All slab subgrades should be saturated to a depth of at least 12-inches prior to placement of slab building materials. Moisture content should be tested in the field by the soil engineer. Slabs subgrade should be kept moist and the surface should not be allowed to desiccate. The addition of fiber mesh in the concrete and careful control of water/cement ratios may lessen the potential for slab cracking. In hot or windy weather, the contractor must take appropriate curing precautions after the placement of concrete. The use of mechanically compacted low slump concrete (not exceeding 4 inches at the time of placement) is recommended. We recommend that a slipsheet (or equivalent) be utilized if grouted tiles or other crack sensitive flooring (such as marble tiles) is planned directly on concrete slabs. 5.6 Slope Protection and Maintenance Proper slope protection and maintenance should help minimize erosion and improve the stability of the existing slopes. As a minimum the slope maintenance guidelines presented in Appendix E of this report should be followed. Additional precautions are:
• Any additional slope planting should be provided by a qualified landscape architect. GeoMat Testing Laboratories, Inc. strongly recommends that erosion and borrowing rodent control measures should be maintained.
• It is critical to provide periodic maintenance and repair of all slopes and drainage systems. Drainage system inlets, outlets, and spillways should be periodically inspected and cleaned of soil and debris.
• It is recommended that all project landscaping be provided with automatic sprinkler shutoffs in order to help prevent over-saturation of slope faces and help mitigate surficial slope instability problems. Leaks in the irrigation system should be fixed without delay.
• The slopes should be periodically inspected for evidence of cracking, erosion, and burrowing animals. Any problems should be repaired immediately.
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5.7 Trench Backfill All utility trenches and retaining wall backfills should be mechanically compacted to the minimum requirements of at least 90 percent relative compaction. Onsite soils derived from trench excavations can be used as trench backfill except for deleterious materials. Soils with sand equivalent greater than 30 may be utilized for pipe bedding and shading. Pipe bedding should be required to provide uniform support for piping. Excavated material from footing trenches should not be placed in slab-on-grade areas unless properly compacted and tested. 5.8 Site Drainage Positive drainage should be provided and maintained for the life of the project around the perimeter of all structures (including slopes and retaining walls) and all foundations toward streets or approved drainage devices to minimize water infiltrating into the underlying natural and engineered fill soils. In addition, finish subgrade adjacent to exterior footings should be sloped down (at least 2%) and away to facilitate surface drainage. Perimeter water collection devices may be installed around the structure to collect roof/irrigation/natural drainage. Roof drainage should be collected and directed away from foundations via nonerosive devices. Over the slope drainage must not be permitted. Water, either natural or by irrigation, should not be permitted to pond or saturate the foundation soils. Planter areas and large trees adjacent to the foundations are not recommended. All planters and terraces should be provided with drainage devices. Internal drainage should be directed to approved drainage collection devices. Location of drainage device should be in accordance with the design civil engineers’ drainage and erosion control recommendations. The owner should be made aware of the potential problems, which may develop when drainage is altered through construction of retaining walls, patios and other devices. Ponded water, leaking irrigation systems, over watering or other conditions which could lead to ground saturation should be avoided. Surface and subsurface runoff from adjacent properties should be controlled. Area drainage collection should be directed through approved drainage devices. All drainage devices should be properly maintained.
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6.0 ADDITIONAL SERVICES
Plan Reviews The recommendations provided in this report are based on preliminary information and subsurface conditions as interpreted from limited exploratory trenches at the site. We should be retained to review final grading and foundation plans to revise our conclusions and recommendations, as necessary. Professional fees will apply for each review. Our conclusions and recommendations should also be reviewed and verified during site grading and revised accordingly if exposed geotechnical conditions vary from our preliminary findings and interpretations. Additional Observation and/or Testing GeoMat Testing Laboratories, Inc. should observe and/or test at the following stages of construction. • Following new footing excavation and prior to placement of footing materials. • During wetting of new slab subgrade and prior to placement of slab materials. • During all trench backfill. • When any unusual conditions are encountered. Final Report of Compaction During Grading A final report of compaction control should be prepared subsequent to the completion of grading. The report should include a summary of work performed, laboratory test results, and the results and locations of field density tests performed during grading.
26871 Highwood Avenue Project No. 19001-01 Laguna Hills, California June 11, 2019
GeoMat Testing Laboratories, Inc. Page 15
7.0 GEOTECHNICAL RISK
The concept of risk is an important aspect of the geotechnical evaluation. The primary reason for this is that the analytical methods used to develop geotechnical recommendations do not comprise an exact science. The analytical tools which geotechnical engineers use are generally empirical and must be used in conjunction with engineering judgment and experience. Therefore, the solutions and recommendations presented in the geotechnical evaluation should not be considered risk-free and, more importantly, are not a guarantee that the interaction between the soils and the proposed structure will perform as planned. The engineering recommendations presented in the preceding sections constitute GeoMat Testing Laboratories professional estimate of those measures that are necessary for the proposed development to perform according to the proposed design based on the information generated and referenced during this evaluation, and GeoMat Testing Laboratories experience in working with these conditions.
8.0 LIMITATION OF INVESTIGATION
This report was prepared for the exclusive use on the new construction. The use by others, or for the purposes other than intended, is at the user’s sole risk. Our investigation was performed using the degree of care and skill ordinarily exercised, under similar circumstances, by reputable Geotechnical Engineers practicing in this or similar locations within the limitations of scope, schedule, and budget. No other warranty, expressed or implied, is made as to the conclusions and professional advice included in this report. The field and laboratory test data are believed representative of the site; however, soil conditions can vary significantly. As in most projects, conditions revealed during construction may be at variance with preliminary findings. If this condition occurs, the possible variations must be evaluated by the Project Geotechnical Engineer and adjusted as required or alternate design recommended. This report is issued with the understanding that it is the responsibility of the owner, or his representative, to ensure that the information and recommendations contained herein are brought to the attention of the engineer for the addition and incorporated into the plans, and the necessary steps are taken to see that the contractor and subcontractor carry out such recommendations in the field. This firm does not practice or consult in the field of safety engineering. We do not direct the contractor's operations, and we cannot be responsible for other than our own personnel on the site; therefore, the safety of others is the responsibility of the contractor. The contractor should notify the owner if he considers any of the recommended actions presented herein to be unsafe. The findings, conclusions, and recommendations presented herein are based on our understanding of the addition and on subsurface conditions observed during our site work, and are valid as of the present date. However, changes in the conditions of a property can occur with the passage of time, whether they be due to natural processes or the works of man on this or adjacent properties. In addition, changes in applicable or appropriate standards may occur, whether they result from legislation or the broadening of knowledge.
PROJECT: 26871 Highwood Drive, Laguna Hills, CA PROJECT NO: 19097-01
REGIONAL GEOLOGY MAP
DATE: June 2018
SITE
From: “Geologic Map of the San Bernardino and Santa Ana 30’x60’ Quadrangles, California,” by Morton, D.M. and Miller, F.K., 2006, US Geological Survey OF-2006-1217.
N
LEGEND:
FIGURE 2
PROJECT: 26871 Highwood Drive, Laguna Hills, CA PROJECT NO: 19097-01
REGIONAL FAULT MAP
DATE: June 2019
N
Approx Scale 1”=13 Miles
From: “Fault Activity Map of California,” compiled by Charles W. Jennings and William A. Bryant, California Geological Survey, Map No. 6, California Geologic Data Map Series, 2010
LEGEND:
SITE
FIGURE 3
PROJECT: 26871 Highwood Drive, Laguna Hills, CA PROJECT NO: 19097-01
SEISMIC HAZARD ZONES MAP
DATE: June 2019
SITE
N
PLATE 1
PROJECT NO: 19097-01
GEOLOGIC SITE MAP
DATE: June 2019 PROJECT: 26871 Highwood Drive, Laguna Hills, CA
Approximate Location of Exploratory Test Pit Excavation
26871 HIGHWOOD DRIVE LAGUNA HILLS, CALIF.
LEGEND
APPROX SCALE 1”=20’
NORTH
A A’
Approximate Location of Geologic Cross Section Alignment
A
A’
TP-1
Shallow Fill and/or Colluvial Soil
over Capistrano Fm Bedrock
Approximate Strike and Dip of Bedding (from Test Pits)
Af/Col Tcs
TP-3 TP-4
10°
10°
TP-1
TP-2
B’
B
(Horiz.)
Af/Col Tcs
Col Tcs
Af/Col Tcs
Af/Col Tcs
DRAFT IN PROGRESS….
Existing 2-Story Residence
PLATE 2
PROJECT NO: 19097-01
GEOLOGIC CROSS SECTIONS A-A’ & B-B’
DATE: June 2019 PROJECT: 26871 Highwood Drive, Laguna Hills, CA
APPROX. SCALE 1”=20’
A A’
400’ 400’
360’
380’
360’
380’
340’ 340’
N 66 E
Natural Soil
Highwood Drive
Fill
PL
TP-3
TP-1
Tcs Capistrano Formation
Existing 2-Story Residence
Tcs Capistrano Formation
APPROX. SCALE 1”=20’
B B’
400’ 400’
360’
380’
360’
380’
340’ 340’
S 71 E
Natural Soil
Highwood
Drive
Fill
PL
TP-3
TP-2
Tcs Capistrano Formation
Existing 2-Story Residence
Tcs Capistrano Formation
DRAFT IN PROGRESS….
HP_Administrator
Rectangle
HP_Administrator
Rectangle
HP_Administrator
TextBox
Plate 3
HNabilsi
Text Box
Appendix A
26871 Highwood Avenue Project No. 19001-01 Laguna Hills, California June 11, 2019
GeoMat Testing Laboratories, Inc. Appendix A
REFERENCES
MF Kessler, Survey Exhibit, 26871 Highwood Circle, Laguna Hills, Ca. 92653. Morton, D.M., and Miller, F.K., 2006, Geologic map of the San Bernardino and Santa Ana 30' x 60' quadrangles, California: U.S. Geological Survey, Open-File Report OF-2006-1217, scale 1:100,000. Jennings, Charles and Bryant, William, 2010, “Fault Activity Map of California,” California Geological Survey, Map No. 6, California Data Map Series, scale 1:750,000. CGS, Earthquake Zones of Required Investigation and Seismic hazard Zones, San Juan Capistrano Quadrangle. December 21, 2001 CDMG, Seismic Hazard Zone Report for the San Juan Capistrano 7.5-Minute Quadrangle, Orange County, 2001. Structural Engineers Association of California, OSHPD Seismic Design Maps Interactive Website (https://seismicmaps.org/) Department of the Navy, Design Manual 7.01, Soil Mechanics, September 1986. Department of the Navy, Design Manual 7.02, Foundation and Earth Structures, September 1986. Robert Day, Geotechnical Foundation Handbook. Foundation Engineering Handbook, Hsai-Yang Fang
MORE THAN 50%OF MATERIAL ISLARGER THAN NO.200 SIEVE SIZE
MORE THAN 50% OFCOARSE FRACTIONRETAINED ON NO. 4SIEVE
SAND ANDSANDY SOILS
MORE THAN 50% OFCOARSE FRACTIONPASSING NO. 4 SIEVE
SOIL CLASSIFICATION CHART
SYMBOLS
CLEANGRAVELS
(LITTLE OR NOFINES)
GRAVELS WITHFINES
(APPRECIABLEAMOUNT OF FINES)
CLEAN SANDS(LITTLE OR NO
FINES)
SANDS WITHFINES
(APPRECIABLEAMOUNT OF FINES)
FINE GRAINEDSOILS
MORE THAN 50%OF MATERIAL ISSMALLER THAN NO.200 SIEVE SIZE
SILTS ANDCLAYS
LIQUID LIMIT LESSTHAN 50
GW
GP
GC
SW
SP
SM
SC
ML
CL
OL
MH
SILTS ANDCLAYS
HIGHLY ORGANIC SOILS
Other Material Symbols (examples)
Asphalt
Sampler and Symbol Descriptions
Modified California Ring Sample
No Recovery
Standard Penetration Test
Bulk Sample (Auger Cuttings)
Disturbed Type-U Sample
Pitcher Tube Sample
Rock Core Sample
Shelby Tube Sample
Approximate depth of perched water or groundwater
Note: Number of blows required to advance driven sample12" (or length noted) is recorded; blow count recorded forseating interval (initial 6" of drive) is indicated by an asterisk.
LIQUID LIMITGREATER THAN 50
OH
PT
TYPICAL DESCRIPTIONS
WELL-GRADED GRAVELS, GRAVEL - SAND MIXTURES,LITTLE OR NO FINES
POORLY GRADED GRAVELS, GRAVEL - SAND MIXTURES,LITTLE OR NO FINES
SILTY GRAVELS, GRAVEL - SAND - SILT MIXTURES
CLAYEY GRAVELS, GRAVEL - SAND - CLAY MIXTURES
WELL-GRADED SANDS, GRAVELLY SANDS, LITTLE OR NOFINES
POORLY GRADED SANDS, GRAVELLY SANDS, LITTLE ORNO FINES
SILTY SANDS, SAND - SILT MIXTURES
CLAYEY SANDS, SAND - CLAY MIXTURES
INORGANIC SILTS AND VERY FINE SANDS, ROCK FLOUR,SILTY OR CLAYEY FINE SANDS OR CLAYEY SILTS WITHSLIGHT PLASTICITY
INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY,GRAVELLY CLAYS, SANDY CLAYS, SILTY CLAYS, LEANCLAYS
ORGANIC SILTS AND ORGANIC SILTY CLAYS OF LOWPLASTICITY
INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINESANDY OR SILTY SOILS, ELASTIC SILTS
INORGANIC CLAYS OF HIGH PLASTICITY
ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY,ORGANIC SILTS
PEAT, HUMUS, SWAMP SOILS WITH HIGH ORGANICCONTENTS
NOTE: Dual symbols are used to indicate gravels or sand with 5-12% fines and soils with fines classifying as CL-ML. Symbols separated by a slashindicate borderline soil classifications.
Laboratory and Field Test Abbreviations
CBR
COMP
CORR
CON
DSCD
EIECP
LL
PPPERMPI
R-value
SA
SA/HA
SC
UC
California Bearing Ratio (result in parentheses)
Compaction test
Corrosivity test
Consolidation test
Consolidated drained direct shear test
Effective Confined Pressure (result in parentheses)
Expansion Index )result in parentheses)
Liquid limit (Atterberg limits test)
Pocket Penetrometer (result in parentheses [tsf])Saturated Hydrualic Conductivity (result in parentheses [cm/sec])Plasticity Index (Atterberg limits test)
Sieve and Hydrometer Analysis (-200 result in parentheses)
R-Value Test (result in parentheses)
Sieve Analysis (-200 result in parentheses)
Sand Cone Test (moisture in %, dry density in pcf)
Unconfined Compressive Strength test
KEY TO LOG OF BORINGSHEET 1 OF 2
GM
CH
APPENDIX B
PL Plastic limit (Atterberg limits test)
Descriptor
Very Soft
Soft
Medium Firm
Firm
Very Firm
Hard
Unconfined CompressiveStrength (tsf)
< 0.25
0.25 - 0.50
0.50 - 1.0
1.0 - 2.0
2.0 - 4.0
> 4.0
CONSISTENCY OF COHESIVE SOILSPocketPenetrometer (tsf)
< 0.25
0.25 - 0.50
0.50 - 1.0
1.0 - 2.0
2.0 - 4.0
> 4.0
Descriptor
Very Loose
Loose
Medium Dense
Dense
Very Dense
APPARENT DENSITY OF COHESIONLESS SOILS
SPT N60 - Value (blows / foot)
11 - 30
0 - 4
5 - 10Moist
31 - 50
> 50
Descriptor
Trace
Few
Little
Some
Mostly
PERCENT OR PROPORTION OF SOILS
Criteria
Particles are present but estimatedto be less than 5%
5 to 10%
15 to 25%
30 to 45%
50 to 100%
Wet
Damp but no visible water
Visible free water, usually soil is belowwater table
Descriptor
Boulder
Cobble
Gravel
Sand
Silt and Clay
PLASTICITY OF FINE-GRAINED SOILS
Descriptor
Nonplastic
Low
Medium
High
A 1/8-inch thread cannot be rolled at any water content.
Criteria
The thread can barely be rolled, and the lump cannot be formed when drier than the plastic limit.
The thread is easy to roll, and not much time is required to reach the plastic limit; it cannot be rerolled afterreaching the plastic limit. The lump crumbles when drier than the plastic limit.
It takes considerable time rolling and kneading to reach the plastic limit. The thread can be rerolled several timesafter reaching the plastic limit. The lump can be formed without crumbling when drier than the plastic limit.
Descriptor
Weak
Moderate
Strong
CEMENTATION
Criteria
Crumbles or breaks with handling orlittle finger pressure.
Crumbles or breaks with considerablefinger pressure.
Will not crumble or break with fingerpressure.
NOTE: This legend sheet provides descriptors andassociated criteria for required soil description componentsonly. Refer to Caltrans Soil and Rock Logging, Classification,and Presentation Manual (July 2007), Section 2, for tables ofadditional soil description components and discussion of soildescription and identification.
SOIL PARTICLE SIZE
Size
Coarse
Fine
Coarse
Medium
Fine
3/4 inch to 3 inches
> 12 inches
3 to 12 inches
No. 4 Sieve to 3/4 inch
No. 10 Sieve to No. 4 Sieve
No. 40 Sieve to No. 10 Sieve
No. 200 Sieve to No. 40 Sieve
Passing No. 200 Sieve
Torvane (tsf)
0.25 - 0.50
< 0.12
0.12 - 0.25
0.50 - 1.0
1.0 - 2.0
> 2.0
Field Approximation
Easily penetrated several inches by fist
Easily penetrated several inches by thumb
Can be penetrated several inches by thumbwith moderate effort
Readily indented by thumb but penetratedonly with great effort
Indented by thumbnail with difficulty
Readily indented by thumbnail
MOISTURE
Descriptor
Dry
Criteria
Absence of moisture, dusty, dry to the touch
APPENDIX B
KEY TO LOG OF BORINGSHEET 2 OF 2
West
PLATE B-1
LOGGED BY: EFH
PROJECT: 26871 Highwood Circle, Laguna Hills, CA PROJECT NO: 19097-01
TEST PIT LOG No. TP-1
DATE: 5-21-19
VISUAL DESCRIPTION:
SKETCH:
0-1’6”: FILL Mottled brown clayey sand, few small fragments of rock/brick/concrete, firm, moist. 1’6”-2’6”: COLLUVIUM Dark brown sandy clay, few small weathered siltstone fragments, fine caliche veins, stiff, moist. 2’6”-5’: BEDROCK Clayey siltstone, olive-gray to rusty tan-brown color, vaguely bedded, very stiff overall, moist, caliche veins. Bedding: N30E, 10NW (downslope side) Horizontal/wavy (upslope side)
Test Pit Outline
ENGINEERING PROPERTIES:
Depth Moisture (%)
Dry Unit Wt (pcf)
Other
(TD = 5’)
Colluvium
Bedrock
0 -
2’ -
4’ -
Fill
Northwest
PLATE B-2
LOGGED BY: EFH
PROJECT: 26871 Highwood Circle, Laguna Hills, CA PROJECT NO:
TEST PIT LOG No. TP-2
DATE: 5-21-19
VISUAL DESCRIPTION:
SKETCH:
0-2’: COLLUVIUM Dark brown fat clay with sand, few small weathered siltstone fragments, fine caliche veins, stiff, moist. 2’-4’6”: BEDROCK Clayey siltstone and sandy siltstone, dark gray to rust brown color, vaguely bedded, weathered, fractured, very stiff overall, moist, caliche veins. Bedding: Horizontal/wavy
Test Pit Outline
ENGINEERING PROPERTIES:
Depth Moisture (%)
Dry Unit Wt (pcf)
Other
(TD = 4’6”)
Colluvium
Bedrock
0 -
2’ -
4’ -
Northeast
PLATE B-3
LOGGED BY: EFH
PROJECT: 26871 Highwood Circle, Laguna Hills, CA PROJECT NO:
TEST PIT LOG No. TP-3
DATE: 5-21-19
VISUAL DESCRIPTION:
SKETCH:
0-1’: FILL Brown silty sand with gravel, firm, slightly moist. 1’-2’6”: NATURAL SOIL Tan, fine-grained sand, includes clasts of gray siltstone locally, non-cemented. (Fills narrow fissures into bedrock below) 2’6”-3’6”: BEDROCK Sandy siltstone, slightly clayey, gray color, weathered, no discernable bedding, very stiff overall, moist, caliche veins.
Test Pit Outline
ENGINEERING PROPERTIES:
Depth Moisture (%)
Dry Unit Wt (pcf)
Other
(TD = 3’6”)
Nat. Soil
Bedrock
Fill
0 -
2’ -
4’ -
Garage
Driveway
West
PLATE B-4
LOGGED BY: EFH
PROJECT: 26871 Highwood Circle, Laguna Hills, CA PROJECT NO:
TEST PIT LOG No. TP-4
DATE: 5-21-19
VISUAL DESCRIPTION:
SKETCH:
0-2’: FILL Mottled brown clayey sand, few small fragments of rock/concrete, firm, moist. 2’-3’6”: COLLUVIUM Dark brown fat clay with sand, few small weathered siltstone fragments, fine caliche veins, stiff, moist. 3’6”-5’: BEDROCK Sandy siltstone, gray color, weathered, no discernable bedding, very stiff overall, moist, caliche veins.
Test Pit Outline
ENGINEERING PROPERTIES:
Depth Moisture (%)
Dry Unit Wt (pcf)
Other
(TD = 5’)
Colluvium
Bedrock
0 -
2’ -
4’ -
Fill
Appendix C
26871 Highwood Avenue
Laguna Hills, California
Project No. 19097-01
June 11, 2019
ASTM D-3080
Sample Moisture [%] Saturated Moisture [%] Dry Unit Weight [pcf]
31.9 38.7 87.9
DIRECT SHEAR TEST RESULTS
Sample Symbol DescriptionSoil Type
[USCS]
Shear
Strength
Friction Angle,
φ [degrees]
Cohesion, c
[psf]
29.0 559
26.0 499TP1 @ 5' Sandy Clay CL Ultimate
TP1 @ 5' CL PeakSandy Clay
24.1 309TP1 @ 5' Sandy Clay CL Residual
0
500
1000
1500
2000
2500
3000
0 500 1000 1500 2000 2500 3000
She
ar S
tre
ss (
psf
)
Normal Stress (psf)
GeoMat Testing Laboratories, Inc. Appendix C
26871 Highwood Avenue
Laguna Hills, California
Project No. 19097-01
June 11, 2019
ASTM D-3080
Sample Moisture [%] Saturated Moisture [%] Dry Unit Weight [pcf]
18.4 30.1 84.5
DIRECT SHEAR TEST RESULTS
Sample Symbol DescriptionSoil Type
[USCS]
Shear
Strength
Friction Angle,
φ [degrees]
Cohesion, c
[psf]
28.3 304
27.5 264TP2 @ 2' Sandy Clay CL Ultimate
TP2 @ 2' CL PeakSandy Clay
21.4 284TP2 @ 2' Sandy Clay CL Residual
0
500
1000
1500
2000
2500
3000
0 500 1000 1500 2000 2500 3000
She
ar S
tre
ss (
psf
)
Normal Stress (psf)
GeoMat Testing Laboratories, Inc. Appendix C
26871 Highwaood Avenue
Laguna Hills, California
Project No. 19097-01
June 11, 2019
TP-2 @ 2' Dark Brown Fat Clay with Sand
ASTM D4318Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity
SOLUBLE SULFATE AND CHLORIDE TEST RESULTS Project Name 26871 Highwood Avenue Test Date 06/11/2019
Project No. 19097-01 Date Sampled 05/21/2019
Project Location Laguna Hills, Ca. Sampled By EH
Location in Structure TP2 @ 2’ Sample Type Bulk
Sampled Classification CH Tested By HMN
TESTING INFORMATION Sample weight before drying
Sample weight after drying
Sample Weight Passing No. 10 Sieve 100.0 g
Moisture
Location Mixing Ratio
Dilution Factor
Sulfate Reading
(ppm)
Sulfate Content
Chloride Reading
(ppm)
Chloride Content
pH
(ppm) (%) (ppm) (%)
TP-2 3 1 100 300 0.030
Average Average Average
ACI 318-05 Table 4.3.1 Requirements for Concrete Exposed to Sulfate-Containing Solutions
Sulfate Exposure
Water-Soluble Sulfate (SO4)
In Soil, % by Mass
Sulfate (SO4) In Water
ppm Cement Type
Maximum w/cm
by Mass
Minimum Design Compressive Strength
fc, MPa (psi)
Negligible < 0.10 < 150 No Special Type -- --
Moderate (see water)
0.10 to 0.20 150 to 1500
II IP(MS), IS(MS),
P(MS), I(PM)(MS), I(SM)(MS)
0.50 28 (4000)
Severe 0.20 to 2.00 1500 to 10,000
V 0.45 31 (4500)
Very Severe > 2.00 >10,000 V + pozz 0.45 31 (4500)
Caltrans classifies a site as corrosive to structural concrete as an area where soil and/or water contains >500pp chloride, >2000ppm sulfate, or has a pH <5.5. A minimum resistivity of less than 1000 ohm-cm indicates the potential for corrosive environment requiring testing for the above criteria. The 2007 CBC Section 1904A references ACI 318 for material selection and mix design for reinforced concrete dependant on the onsite corrosion potential, soluble chloride content, and soluble sulfate content in soil
Comments:Sec 4.3 of ACI 318 (2005) Soil environment is detrimental to concrete if it has soluble sulfate
>1000ppm and/or pH<5.5. Soil environment is corrosive to reinforcement and steel pipes if Chloride ion
>500ppm or pH <4.0.
Signature Date
Print Name Title
The information in this form is not intended for corrosion engineering design. If corrosion is critical, a corrosion specialist should be contacted to provide further recommendations.
CRS 0.978 Mapped value of the risk coefficient at short periods
Page 1 of 3U.S. Seismic Design Maps
6/11/2019https://seismicmaps.org/
Type Value Description
CR1 1.022 Mapped value of the risk coefficient at a period of 1 s
Page 2 of 3U.S. Seismic Design Maps
6/11/2019https://seismicmaps.org/
DISCLAIMER
While the information presented on this website is believed to be correct, SEAOC /OSHPD and its sponsors and contributors assume no
responsibility or liability for its accuracy. The material presented in this web application should not be used or relied upon for any specific application
without competent examination and verification of its accuracy, suitability and applicability by engineers or other licensed professionals. SEAOC /
OSHPD do not intend that the use of this information replace the sound judgment of such competent professionals, having experience and
knowledge in the field of practice, nor to substitute for the standard of care required of such professionals in interpreting and applying the results of
the seismic data provided by this website. Users of the information from this website assume all liability arising from such use. Use of the output of
this website does not imply approval by the governing building code bodies responsible for building code approval and interpretation for the building
site described by latitude/longitude location in the search results of this webstie.
MCER Response Spectrum
Sa(g)
0.0 2.5 5.0 7.50.0
0.5
1.0
1.5
Period, T (sec)
Design Response Spectrum
Sa(g)
0.0 2.5 5.0 7.50.00
0.25
0.50
0.75
1.00
Period, T (sec)
Page 3 of 3U.S. Seismic Design Maps
6/11/2019https://seismicmaps.org/
Appendix E
26871 Highwood Ave Project No. 19097-01 Laguna Hills, California June 11, 2019
GeoMat Testing Laboratories, Inc. Appendix E-1
SLOPE MAINTENANCE GUIDELINES
Hillside lots in general, and hillside slopes in particular, need maintenance to continue to function and retain their value. Many homeowners are unaware of this and allow deterioration of their property. In addition to his own property, the homeowner may be subject to liability for damage occurring to neighboring properties as a result of his negligence. It is therefore important to familiarize homeowners with some guidelines for maintenance of their properties and make them aware of the importance of maintenance. Nature slowly wears away land, but human activities such as construction increase the rate of erosion 200, even 2,000 times that amount. When we remove vegetation or other objects that hold soil in place, we expose it to the action of wind and water, and increase its chance of eroding. The following guidelines are provided for the protection of the homeowner’s investment, and should be employed throughout the year.
(a) Care should be taken that slopes, terraces, berms (ridges at crown of slopes), and proper lot drainage are not disturbed. Surface drainage should be conducted from the rear yard to the street by a graded swale through the sideyard, or alternative approved devices.
(b) In general, roof and yard runoff should be conducted to either the street or storm drain by nonerosive devices such as sidewalks, drainage pipes, ground gutters, and driveways. Drainage systems should not be altered without expert consultation.
(c) All drains should be kept cleaned and unclogged, including gutters and downspouts. Terrace drains or gunite ditches should be kept free of debris to allow proper drainage. During heavy rain periods, performance of the drainage system should be inspected. Problems, such as gullying and ponding, if observed, should be corrected as soon as possible.
(d) Any leakage from pools, waterlines, etc. or bypassing of drains should be repaired as soon as possible.
(e) Animal burrows should be filled since they may cause diversion of surface runoff, promote accelerated erosion, and even trigger shallow soil failures.
(f) Slopes should not be altered without expert consultation. Whenever a homeowner plans a significant topographic modification of the lot or slope, a qualified geotechnical consultant should be contacted.
(g) If plans for modification of cut, fill, or natural slopes within a property are considered, an engineering geologist should be consulted. Any oversteepening may result in a need for
expensive retaining devices. Undercutting of the bottom of a slope might possibly lead to slope instability or failure and should not be undertaken without expert consultation.
(h) If unusual racking, settling, or earth slippage occurs on the property, the homeowner should consult a qualified soil engineer or an engineering geologist immediately.
(i) The most common causes of slope erosion and shallow slope failures are as follows:
❖ Gross negligent of the care and maintenance of the slopes and drainage devices.
❖ Inadequate and/or improper planting. (Barren areas should be replanted as soon as possible.)
❖ Excessive or insufficient irrigation or diversion of runoff over the slope.
❖ Foot traffic on slopes destroying vegetation and exposing soil to erosion potential.
(j) Homeowners should not let conditions on their property create a problem for their neighbors. Cooperation with neighbors could prevent problems; also increase the aesthetic attractiveness of the property.
WINTER ALERT It is especially important to “winterize” your property by mid-September. Don’t wait until spring to put in landscaping. You need winter protection. Final landscaping can be done later. Inexpensive measures installed by mid-September will give you protection quickly that will last all during the wet season. ❖ Check before storms to see that drains, gutters, downspouts,
and ditches are not clogged by leaves and rubble. ❖ Check after major storms to be sure drains are clear and
vegetation is holding on slopes. Repair as necessary. ❖ Spot seed any bare areas. Broadcast seeds or use a
mechanical seeder. A typical slope or bare areas can be done in less than an hour.
❖ Give seeds a boost with fertilizer. ❖ Mulch if you can, with grass clippings and leaves, bark chips or
straw. ❖ Use netting to hold soil and seeds on steep slopes.
26871 Highwood Ave Project No. 19097-01 Laguna Hills, California June 11, 2019
GeoMat Testing Laboratories, Inc. Appendix E-2
❖ Check with your landscape architect or local nursery for advice. ❖ Prepare berms and ditches to drain surface runoff water away
from problem areas such as steep, bare slopes. ❖ Prepare base areas on slopes for seeding by raking the surface
to loosen and roughen soil so it will hold seeds.
CONSTRUCTION ❖ Plan construction activities during spring and summer, so that
erosion control measures can be in place when the rain comes. ❖ Examine your site carefully before building. Be aware of the
slope, drainage patterns and soil types. Proper site design will help you avoid expensive stabilization work.
❖ Preserve existing vegetation as much as possible. Vegetation
will naturally curb erosion, improve the appearance and value of your property, and reduce the cost of landscaping later.
❖ Use fencing to protect plants from fill material and traffic. If you
have to pave near trees, do so with permeable asphalt or porous paving blocks.
❖ Minimize the length and steepness of slopes by benching,
terracing, or constructing diversion structures. Landscape benched areas to stabilize the slope and improve its appearance.
❖ As soon as possible after grading a site, plant vegetation on all
areas that are not to be paved or otherwise covered.
TEMPORARY MEASURES TO STABILIZE THE SOIL
Grass provides the cheapest and most effective short-term erosion control. It grows quickly and covers the ground completely. To find the best seed mixtures and plants for your area, check with your local landscape architect, local nursery, or the U.S. Department of Agriculture Soil Conservation Service. Mulches hold soil moisture and provide ground protection from rain drainage. They also provide a favorable environment for starting and growing plants. Easy-to-obtain mulches are grass clippings, leaves, sawdust, bark chips, and straw. Straw mulch is nearly 100 percent effective when held in place by spraying with an organic glue or wood fiber (tackifiers), by punching it into the soil with a shovel or roller, or by tacking a netting over it. Commercial applications of wood fibers combined with various seeds and fertilizers (hydraulic mulching) are effective in stabilizing sloped areas. Hydraulic mulching with a tackifier should be done in two separate applications; the first composed of seed fertilizer and half the mulch, the second composed of the remaining mulch and tackifier. Commercial hydraulic mulch applicators – who also provide
other erosion control services – are listed under “landscaping” in the phone book. Mats of excelsior, jute netting, and plastic sheets can be effective temporary covers, but they must be in contact with the soil and fastened securely to work effectively. Roof drainage can be collected in barrels or storage containers or touted into lawns, planter boxes, and gardens. Be sure to cover stored water so you don’t collect mosquitoes. Excessive runoff should be directed away from your house. Too much water can damage tress and make foundations unstable.
STRUCTURAL RUNOFF CONTROLS Even with proper timing and planting, you may need to protect disturbed areas from rainfall until the plants have time to establish themselves. Or you may need permanent ways to transport water across your property so that it doesn’t cause erosion. To keep water from carrying soil from your site and dumping it into nearby lots, streets, streams and channels, you need ways to reduce its volume and speed. Some examples of what you might use are: ❖ Riprap (rock lining) – to protect channel banks from erosive
water flow. ❖ Sediment trap – to stop runoff carrying sediment and trap the
sediment. ❖ Storm drain outlet protection – to reduce the speed of water
flowing from a pipe onto open ground or into a natural channel. ❖ Diversion dike or perimeter dike – to divert excess water to
places where it can be disposed of properly. ❖ Straw bale dike – to stop and detain sediment from small-
unprotected areas (a short-term measure). ❖ Perimeter swale – to divert runoff from a disturbed area or to
contain runoff within a disturbed area. ❖ Grade stabilization structure – to carry concentrated runoff down
a slope.
Appendix F
GALENA Version 7.1
Project Global Stability of Existing Slope Static
File: C:\Users\Haytham\Documents\GEOMAT DATA\ANNUAL REPORTS\2019 REPORTS\19097.Laguna Hills\Galena\Static.gmf GeoMat Testing Laboratories, Inc.
Edited: Processed:11 Jun 2019 11 Jun 2019
Analysis
Results
1
Multiple Stability Analysis
Bishop Simplified
Circular
Method:
Surface:
Critical Factor of Safety: 2.17
FoS Ranges <=1.00 >1.00 <=1.20 >1.20 <=1.40 >1.40 Material Keys
1: Natural Soil
2: Bedrock
-40 -20 0 20 40 60 80 100 120 140
320
340
360
380
400
420
440
1000
GLOBAL STABILITY OF EXISTING SLOPE
GALENA 7.1 Analysis Results Version: 7.10.1.02 Licensee: GeoMat Testing Laboratories, Inc.———————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————— Project: Global Stability of Existing Slope File: C:\Users\Haytham\Documents\GEOMAT DATA\ANNUAL REPORTS\2019 REPORTS\19097.Laguna Hills\Galena\Static.gmfProcessed: 11 Jun 2019 18:46:54————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————