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HomeMy WebLinkAbout182522-30A Rough Grade Report SIGNED Earth Strata Geotechnical Services, Inc. ---- - ----------- ------------------------ Geotechnical, Environmental and Materials Testing Consultants October 14, 2021 Project No. 182522-30A Mr. Scott Hardesty Hardesty&Associates, Inc. 711 W. 171h Street, Unit D-2 Costa, CA Subject: Geotechnical Report of Rough Grading, Proposed Convenience Store, Car Wash and Gas Station, Assessor's Parcel Number 377-243-002 thru 377-243-007, Located on the Southeast Corner of North Main Street and West Flint Street, City of Lake Elsinore, Riverside County, California INTRODUCTION Per your authorization, Earth Strata Geotechnical Services, Inc. has provided observations and testing services during rough grading for the proposed single-family residence, located on north Main Street and West Flint Street in the City of Lake Elsinore, Riverside County, California. This report summarizes the geotechnical conditions observed and tested during rough grading. Conclusions and recommendations with regard to the suitability of the grading for the proposed project are provided herein, along with foundation design recommendations based on the earth materials present at the completion of grading. Grading commenced in order to develop one (1) building pad for construction of one- and/or two-story structures. The proposed development will consist of a commercial gas station utilizing slab on grade, wood or steel-framed construction. Grading operations began in February 2021 and was completed in October 2021. REGULATORY COMPLIANCE Observations and selective testing have been performed by representatives of Earth Strata Geotechnical Services, Inc. during the removal and recompaction of low-density near surface earth materials. Our services were performed in general accordance with the recommendations presented in the referenced reports (see References), the grading code of the reviewing agency, and as dictated by conditions encountered in the field. The earthwork described herein has been reviewed and is considered adequate for the construction now planned. The recommendations presented in this report were prepared in conformance with generally accepted professional engineering practices in this area at the time of this report and no further warranty is expressed or implied. 42184 REMINGTON AVENUE, TEMECULA, CA 92590 951-461-4028, ESGSINC.COM ENGINEERING GEOLOGY Geologic Units Earth materials noted during grading operations included topsoil, Quaternary alluvial materials, and bedrock. Groundwater Groundwater was not encountered during grading operations. Faultine No evidence of significant faulting was observed during grading operations. EARTHWORK OBSERVATIONS AND DENSITY TESTING Site Clearing and Grubbing Prior to grading, all trees,brush, shrubs, and grasses were stripped and removed from the compacted fill. Ground Preparation Removals throughout most of the site ranged from approximately 3 to 10 feet below original grades, with locally deeper removals. Prior to placing compacted fill, the exposed bottom surfaces were scarified to depths of 6 to 8 inches, watered or air dried as necessary to achieve near optimum moisture content and then compacted to a minimum relative compaction of 90 percent. Oversize Rock Oversize rock, generally greater than 1 foot in maximum dimension, was not encountered during the grading operations. Fill Placement and Testing All fills were placed in lifts restricted to approximately 6 to 8 inches in maximum thickness, watered or air dried as necessary to achieve near optimum moisture content, then compacted to a minimum of 90 percent of the maximum dry density by rolling with a bulldozer, sheepsfoot, or loaded scrapers. The maximum vertical depth of compacted fill as a result of grading within the proposed building pads is approximately 3 to 10 feet. IEAIK'7CH STIKATA\ G1E01FIEC1HIMICAL SIEIRVIIC1ES, ]INC.. 2 October 14, 2021 Project Number 182522-30A Benching into competent earth materials was observed during fill placement and compaction operations. Field density and moisture content tests utilizing nuclear gauge methods were performed in accordance with ASTM D 6938. Visual classification of the earth materials in the field was the basis for determining which maximum dry density value was applicable for a given density test. Test results are presented in Table 1 and test locations are shown on the enclosed As-Graded Geotechnical Map, Plate 1. Compacted fills were tested to verify that a minimum of 90 percent of the maximum dry density had been achieved. At least one density test was taken for each 1,000 cubic yards and/or for every 2 vertical feet of compacted fill placed. The actual number of tests taken per day varied depending on the site conditions and the quantity and type of equipment utilized. When field density tests yielded results less than the minimum required density, the approximate limits of the substandard fill were established. The substandard area was then reworked (most common) or removed, moisture conditioned, recompacted, and retested until the minimum density was achieved. In most cases, failed density tests were noted then retested in the same general vicinity at nearly the same elevation as the failed test. Slopes Slopes constructed within the subject property consist of 2:1 (h:v) compacted fill varying to a maximum height of approximately 5 feet. LABORATORY TESTING Maximum Dry Density Maximum dry density and optimum moisture content for representative earth materials noted during grading operations were determined using the guidelines of ASTM D 1557. Pertinent test values are summarized in Appendix B. Expansion Index Tests Expansion index tests were performed on representative earth materials sampled near finish grade for select building pads using the guidelines of ASTM D 4829. Test results are summarized in Appendix B. Soluble Sulfate Analyses The soluble sulfate content of select samples was determined using the guidelines of California Test Method (CTM) 417. Test results are summarized in Appendix B. Chloride Chloride content of select samples was determined using the guidelines of CTM 422. Test results are summarized in Appendix B. Minimum Resistivity and pH Minimum resistivity and pH tests of select samples were determined using the guidelines of CTM 643. Test results are summarized in Appendix B. JEA\R'7CH STRATA G1E01FIEC1HIMICAL SIERVAC1ES, ]INC.. 3 October 14, 2021 Project Number 182522-30A POST GRADING CONSIDERATIONS Slope Landscaping and Maintenance Control of site drainage is important for the performance of the proposed project. Engineered slopes should be landscaped with deep rooted, drought tolerant, maintenance free plant species, as recommended by the project landscape architect. Unprotected slopes are highly susceptible to erosion and surficial slumping. Therefore to reduce this potential, we recommend that the slopes be covered with an erosion inhibitor until healthy plant growth is well established. To further reduce the potential for surficial instability, measures to control burrowing rodents should be performed as well. Site Drainage Adequate slope and building pad drainage is essential for the long term performance of the subject site. The gross stability of graded slopes should not be adversely affected, provided all drainage provisions are properly constructed and maintained. Roof gutters are recommended for the proposed structures. Pad and roof drainage should be collected and transferred to driveways, adjacent streets, storm-drain facilities, or other locations approved by the building official in non-erosive drainage devices. Drainage should not be allowed to pond on the pad or against any foundation or retaining wall. Drainage should not be allowed to flow uncontrolled over any descending slope. Planters located within retaining wall backfill should be sealed to prevent moisture intrusion into the backfill. Planters located next to raised floor type construction should be sealed to the depth of the footings. Drainage control devices require periodic cleaning,testing, and maintenance to remain effective. At a minimum, pad drainage should be designed at the minimum gradients required by the CBC. To divert water away from foundations, the ground surface adjacent to foundations should be graded at the minimum gradients required per the CBC. Utility Trenches All utility trench backfill should be compacted to a minimum of 90 percent of the maximum dry density determined by ASTM D 1557. For utility trench backfill in pavement areas the upper 6 inches of subgrade materials should be compacted to 95 percent of the maximum dry density determined by ASTM D 1557. This includes within the street right-of-ways, utility easements, under footings, sidewalks, driveways and building floor slabs, as well as within or adjacent to any slopes. Backfill should be placed in approximately 6 to 8 inch maximum loose lifts and then mechanically compacted with a hydro- hammer, rolling with a sheepsfoot, pneumatic tampers, or similar equipment. The utility trenches should be tested by the project geotechnical engineer or their representative to verify minimum compaction requirements are obtained. In order to minimize the penetration of moisture below building slabs, all utility trenches should be backfilled with compacted fill, lean concrete, or concrete slurry where they undercut the perimeter foundation. Utility trenches that are proposed parallel to any building footings (interior and/or exterior trenches), should not be located within a 1:1 (h:v) plane projected downward from the outside bottom edge of the footing. JEA\R'7CH STRATA G1E01FIEC1HIMICAL SIERVAC1ES, ]INC.. 4 October 14, 2021 Project Number 182522-30A FOUNDATION DESIGN RECOMMENDATIONS General Conventional foundations are recommended for support of the proposed structures. Foundation recommendations are provided herein. Allowable Bearing Values An allowable bearing value of 2,000 pounds per square foot (psf) is recommended for design of 24 inch square pad footings and 12 inch wide continuous footings founded at a minimum depth of 12 inches below the lowest adjacent final grade. This value may be increased by 20 percent for each additional 1-foot of width and/or depth to a maximum value of 2,500 psf. Recommended allowable bearing values include both dead and frequently applied live loads and may be increased by one third when designing for short duration wind or seismic forces. Settlement Based on the settlement characteristics of the earth materials that underlie the building sites and the anticipated loading, we estimate that the maximum total settlement of the footings will be less than approximately 3/4 inch. Differential settlement is expected to be about 1/2 inch over a horizontal distance of approximately 20 feet, for an angular distortion ratio of 1:480. It is anticipated that the majority of the settlement will occur during construction or shortly after the initial application of loading. The above settlement estimates are based on the assumption that the construction is performed in accordance with the recommendations presented in this report and that the project geotechnical consultant will observe or test the earth material conditions in the footing excavations. Lateral Resistance Passive earth pressure of 250 psf per foot of depth to a maximum value of 2,500 psf may be used to establish lateral bearing resistance for footings. A coefficient of friction of 0.36 times the dead load forces may be used between concrete and the supporting earth materials to determine lateral sliding resistance. The above values may be increased by one-third when designing for short duration wind or seismic forces. When combining passive and friction for lateral resistance, the passive component should be reduced by one third. In no case shall the lateral sliding resistance exceed one-half the dead load for clay, sandy clay, sandy silty clay, silty clay, and clayey silt. The above lateral resistance values are based on footings for an entire structure being placed directly against compacted fill. Structural Setbacks Structural setbacks are required per the 2019 California Building Code (CBC). Additional structural setbacks are not required due to geologic or geotechnical conditions within the site. Improvements constructed in close proximity to natural or properly engineered and compacted slopes can, over time, be affected by natural processes including gravity forces, weathering, and long term secondary settlement. IEAIK'7CH STIKATA\ G1E01FIEC1HIMICAL SIER\ AC1ES, ]INC.. 5 October 14, 2021 Project Number 182522-30A As a result, the CBC requires that buildings and structures be setback or footings deepened to resist the influence of these processes. For structures that are planned near ascending and descending slopes, the footings should be embedded to satisfy the requirements presented in the CBC, Section 1808.7 as illustrated in the following Foundation Clearances From Slopes diagram. FOUNDATION CLEARANCES FROM SLOPES Earth - Strata, Inc. 2019 CALIFORNIA BUILDING CODE ,Ea rth BUILDING SETBACK DIMENSIONS PACE or Pon�q-� rd OF ltdt -V!iUT KM KOT TO (IOCE(0 Aft►HT MAX PACE OF H 5T9.KT 1vPXV'N"DP4OTPXCRb 15 FEFT MAX -------------------------------- TO&OF SLOW* When determining the required clearance from ascending slopes with a retaining wall at the toe, the height of the slope shall be measured from the top of the wall to the top of the slope. ]EAlK'7CH STIKATA\ G1E01FIEC1HIN11CAL 1EIR'VAC1ES, ]INC.. 6 October 14, 2021 Project Number 182522-30A Footing Observations Prior to the placement of forms, concrete, or steel, all foundation excavations should be observed by the geologist, engineer, or his representative to verify that they have been excavated into competent bearing materials. The excavations should be moistened, cleaned of all loose materials, trimmed neat, level and square and any moisture softened earth materials should be removed prior to concrete placement. Earth materials from foundation excavations should not be placed in slab on grade areas unless the materials are tested for expansion potential and compacted to a minimum of 90 percent of the maximum dry density. Expansive Soil Considerations Laboratory test results indicate onsite earth materials exhibit an expansion potential of VERY LOW as classified in accordance with 2019 CBC Section 1803.5.3 and ASTM D 4829. The following recommendations should be considered the very minimum requirements, for the earth materials tested. It is common practice for the project architect or structural engineer to require additional slab thickness, footing sizes, and/or reinforcement. Very Low Expansion Potential (Expansion Index of 20 or Less) Our laboratory test results indicate that the earth materials onsite exhibit a VERY LOW expansion potential as classified in accordance with 2019 CBC Section 1803.5.3 and ASTM D 4829. Since the onsite earth materials exhibit expansion indices of 20 or less, the design of slab on ground foundations is exempt from the procedures outlined in Sections 1808.6.1 and 1808.6.2. Footings • Exterior continuous footings may be founded at the minimum depths below the lowest adjacent final grade (i.e. 12 inch minimum depth for one-story, 18 inch minimum depth for two-story, and 24 inch minimum depth for three-story construction). Interior continuous footings for one-,two-, and three-story construction may be founded at a minimum depth of 12 inches below the lowest adjacent final grade. All continuous footings should have a minimum width of 12, 15, and 18 inches, for one-, two-, and three-story structures, respectively, per Table 1809.7 of the 2019 CBC and should be reinforced with a minimum of two (2) No. 4 bars, one (1) top and one (1) bottom. • Exterior pad footings intended to support roof overhangs, such as second story decks, patio covers and similar construction should be a minimum of 24 inches square and founded at a minimum depth of 18 inches below the lowest adjacent final grade. No special reinforcement of the pad footings will be required. IEAIK'7CH TIKATA\ G1EOTIEC1HN111CA1L SIEIE NIC1ES, ]INC.. 7 October 14, 2021 Project Number 182522-30A Building Floor Slabs • Building floor slabs should be a minimum of 4 inches thick and reinforced with a minimum of No. 3 bars spaced a maximum of 24 inches on center, each way. All floor slab reinforcement should be supported on concrete chairs or bricks to ensure the desired placement at mid- depth. • Interior floor slabs, within living or moisture sensitive areas, should be underlain by a minimum 10-mil thick moisture/vapor barrier to help reduce the upward migration of moisture from the underlying earth materials. The moisture/vapor barrier used should meet the performance standards of an ASTM E 1745 Class A material, and be properly installed in accordance with ACI publication 318-05. It is the responsibility of the contractor to ensure that the moisture/vapor barriers are free of openings, rips, or punctures prior to placing concrete. As an option for additional moisture reduction, higher strength concrete, such as a minimum 28-day compressive strength of 5,000 pounds per square inch (psi) may be used. Ultimately, the design of the moisture/vapor barrier system and recommendations for concrete placement and curing are the purview of the foundation engineer, taking into consideration the project requirements provided by the architect and owner. • Garage floor slabs should be a minimum of 4 inches thick and should be reinforced in a similar manner as living area floor slabs. Garage floor slabs should be placed separately from adjacent wall footings with a positive separation maintained with % inch minimum felt expansion joint materials and quartered with weakened plane joints. A 12 inch wide turn down founded at the same depth as adjacent footings should be provided across garage entrances. The turn down should be reinforced with a minimum of two (2) No. 4 bars, one (1) top and one (1) bottom. • The subgrade earth materials below all floor slabs should be pre-watered to promote uniform curing of the concrete and minimize the development of shrinkage cracks, prior to placing concrete. The pre-watering should be verified by Earth Strata Geotechnical Services during construction. Post Tensioned Slab/Foundation Design Recommendations In lieu of the proceeding foundation recommendations, post tensioned slabs may be used to support the proposed structures. We recommend that the foundation engineer design the foundation system using the Post Tensioned Foundation Slab Design table below. These parameters have been provided in general accordance with Post Tensioned Design. Alternate designs addressing the effects of expansive earth materials are allowed per 2019 CBC Section 1808.6.2. When utilizing these parameters, the foundation engineer should design the foundation system in accordance with the allowable deflection criteria of applicable codes and per the requirements of the structural engineer/architect. It should be noted that the post tensioned design methodology is partially based on the assumption that soil moisture changes around and underneath post tensioned slabs, are influenced only by climate conditions. Soil moisture change below slabs is the major factor in foundation damages relating to expansive soil. However, the design methodology has no consideration for presaturation, owner irrigation, or other non-climate related influences on the moisture content of subgrade earth materials. JEA\R'7CH STRATA G1E01FIEC1HIMICAL SIERVAC1ES, ]INC.. 8 October 14, 2021 Project Number 182522-30A In recognition of these factors, we modified the geotechnical parameters determined from this methodology to account for reasonable irrigation practices and proper homeowner maintenance. Additionally, we recommend that prior to excavating footings, slab subgrades be presoaked to a depth of 12 inches and maintained at above optimum moisture until placing concrete. Furthermore, we recommend that the moisture content of the earth materials around the immediate perimeter and below the slab be presaturated to at least 1% above optimum moisture content just prior to placing concrete. The pre-watering should be verified and tested by Earth Strata Geotechnical Services during construction. The following geotechnical parameters assume that areas adjacent to the foundations, which are planted and irrigated,will be designed with proper drainage to prevent water from ponding. Water ponding near the foundation causes significant moisture change below the foundation. Our recommendations do not account for excessive irrigation and/or incorrect landscape design. Planters placed adjacent to the foundation, should be designed with an effective drainage system or liners, to prevent moisture infiltration below the foundation. Some lifting of the perimeter foundation beam should be expected even with properly constructed planters. Based on our experience monitoring sites with similar earth materials, elevated moisture contents below the foundation perimeter due to incorrect landscaping irrigation or maintenance, can result in uplift at the perimeter foundation relative to the central portion of the slab. Future owners should be informed and educated of the importance in maintaining a consistent level of moisture within the earth materials around the structures. Future owners should also be informed of the potential negative consequences of either excessive watering, or allowing expansive earth materials to become too dry. Earth materials will shrink as they dry, followed by swelling during the rainy winter season, or when irrigation is resumed. This will cause distress to site improvements and structures. JEA\R'7CH STRATA G1E01FIEC1HIMICAL SIERVAC1ES, ]INC.. 9 October 14, 2021 Project Number 182522-30A Post Tensioned Foundation Slab Design PARAMETER VALUE Expansion Index Very Low' Percent Finer than 0.002 mm in the <20 percent(assumed) Fraction Passing the No. 200 Sieve Type of Clay Mineral Montmorillonite assumed Thornthwaite Moisture Index +20 Depth to Constant Soil Suction 7 feet Constant Soil Suction P.F. 3.6 Moisture Velocity 0.7 inches month Center Lift Edge moisture 5.5 feet variation distance,em 1.5 inches Center lift,y. Edge Lift Edge moisture 2.5 feet variation distance,em 0.4 inches Edge lift,ym Soluble Sulfate Content for Design of Concrete Mixtures in Contact with Earth Negligible Materials Modulus of Subgrade Reaction, k (assuming presaturation as indicated 200 pci below Minimum Perimeter Foundation 12 Embedment Perimeter Foundation Reinforcement -- Under Slab Moisture/Vapor Barrier and 10-mil thick moisture/vapor barrier meeting the requirements of a ASTM E 1745 Sand Layer Class A material LAssumed for design purposes or obtained by laboratory testing. 1. 2. Recommendations for foundation reinforcement are ultimately the purview of the foundation/structural engineer based upon the geotechnical criteria presented in this report,and structural engineering considerations. Corrosivity Corrosion is defined by the National Association of Corrosion Engineers (NACE) as "a deterioration of a substance or its properties because of a reaction with its environment." From a geotechnical viewpoint, the "substances" are the reinforced concrete foundations or buried metallic elements (not surrounded by concrete) and the "environment" is the prevailing earth materials in contact with them. Many factors can contribute to corrosivity, including the presence of chlorides, sulfates, salts, organic materials, different oxygen levels, poor drainage, different soil types, and moisture content. It is not considered practical or realistic to test for all of the factors which may contribute to corrosivity. The potential for concrete exposure to chlorides is based upon the recognized Caltrans reference standard "Bridge Design Specifications", under Subsection 8.22.1 of that document, Caltrans has determined that "Corrosive water or soil contains more than 500 parts per million (ppm) of chlorides". Based on limited preliminary laboratory testing, the onsite earth materials have chloride contents less than 500 ppm. As such,specific requirements resulting from elevated chloride contents are not required. Specific guidelines for concrete mix design are provided in 2019 CBC Section 1904.1 and ACI 318, Section JEA\R'7CH STRATA G1EOTIEC1HN,11CA1L SIEIE VIC1ES, ]INC.. 10 October 14, 2021 Project Number 182522-30A 4.3 Table 4.3.1 when the soluble sulfate content of earth materials exceeds 0.1 percent by weight. Based on limited preliminary laboratory testing, the onsite earth materials are classified in accordance with Table 4.3.1 as having a negligible sulfate exposure condition. Therefore, structural concrete in contact with onsite earth materials should utilize Type I or II. Based on our laboratory testing of resistivity, the onsite earth materials in contact with buried steel should be considered mildly corrosive. Additionally, pH values below 5.6 and above 9.1 are recognized as being corrosive to many common metallic components. The pH values for the earth materials tested were lower than 9.1 and higher than 5.6. If building slabs are to be post tensioned,the post tensioning cables should be encased in concrete and/or encapsulated in accordance with the Post Tensioning Institute Guide Specifications. Post tensioning cable end plate anchors and nuts also need to be protected if exposed. If the anchor plates and nuts are in a recess in the edge of the concrete slab, the recess should be filled in with a non-shrink, non-porous, moisture-insensitive epoxy grout so that the anchorage assembly and the end of the cable are completely encased and isolated from the soil. A standard non-shrink, non-metallic cementitious grout may be used only when the post tension anchoring assembly is polyethylene encapsulated similar to that offered by Hayes Industries, LTD or O'Strand, Inc. The test results for corrosivity are based on limited samples in accordance with the current standard of care. Laboratory test results are presented in Appendix B. RETAINING WALLS Active and At-Rest Earth Pressures Foundations may be designed in accordance with the recommendations provided in the Foundation Design Recommendation section of this report. The following table provides the minimum recommended equivalent fluid pressures for design of retaining walls a maximum of 8 feet high. The active earth pressure should be used for design of unrestrained retaining walls, which are free to tilt slightly. The at-rest earth pressure should be used for design of retaining walls that are restrained at the top, such as basement walls, curved walls with no joints, or walls restrained at corners. For curved walls, active pressure may be used if tilting is acceptable and construction joints are provided at each angle point and at a minimum of 15 foot intervals along the curved segments. MINIMUM STATIC EQUIVALENT FLUID PRESSURES c PRESSURE TYPE BACKSLOPE CONDITION LEVEL 2:1 h:v Active Earth Pressure 35 52 At-Rest Earth Pressure 53 78 1EA\1MF1H[ S'7 R AV FA G1EMFIEC1HNIN CA\1L SIER\ I C1ES, 1[NC.. 11 October 14, 2021 Project Number 182522-30A The retaining wall parameters provided do not account for hydrostatic pressure behind the retaining walls. Therefore, the subdrain system is a very important part of the design. All retaining walls should be designed to resist surcharge loads imposed by other nearby walls, structures, or vehicles should be added to the above earth pressures, if the additional loads are being applied within a 1:1 plane projected up from the heel of the retaining wall footing. As a way of minimizing surcharge loads and the settlement potential of nearby buildings,the footings for the building can be deepened below the 1:1 plane projected up from the heel of the retaining wall footing. Upon request and under a separate scope of work, more detailed analyses can be performed to address equivalent fluid pressures with regard to stepped retaining walls, actual retaining wall heights, actual backfill inclinations,specific backfill materials,etc. Subdrain System We recommend a perforated pipe and gravel subdrain system be provided behind all proposed retaining walls to prevent the buildup of hydrostatic pressure behind the proposed retaining walls. The perforated pipe should consist of 4 inch minimum diameter Schedule 40 PVC or ABS SDR-3S, placed with the perforations facing down. The pipe should be surrounded by 1 cubic foot per foot of 3/4- or 11/z inch open graded gravel wrapped in filter fabric. The filter fabric should consist of Mirafi 140N or equivalent to prevent infiltration of fines and subsequent clogging of the subdrain system. In lieu of a perforated pipe and gravel subdrain system, weep holes or open vertical masonry joints may be provided in the lowest row of block exposed to the air to prevent the buildup of hydrostatic pressure behind the proposed retaining walls. Weep holes should be a minimum of 3 inches in diameter and provided at minimum intervals of every 6 feet along the wall. Open vertical masonry joints should be provided at a minimum of 32 inch intervals. A continuous gravel fill, a minimum of 1 cubic foot per foot, should be placed behind the weep holes or open masonry joints. The gravel should be wrapped in filter fabric consisting of Mirafi 140N or equivalent. The adequate retaining walls should be coated on the backfilled side of the walls with a proven waterproofing compound by an experienced professional to inhibit infiltration of moisture through the walls. Temporary Excavations All excavations should be made in accordance with OSHA requirements. Earth Strata Geotechnical Services is not responsible for job site safety. Wall Backfill Retaining-wall backfill materials should be approved by the geotechnical engineer or his representative prior to placement as compacted fill. Retaining wall backfill should be placed in lifts no greater than 6 to 8 inches,watered or air dried as necessary to achieve near optimum moisture contents. All retaining wall backfill should be compacted to a minimum of 90 percent of the maximum density as determined by ASTM D 1SS7. Retaining wall backfill should be capped with a paved surface drain. JEA\RTIH[ STRATA G1E01FIEC1HIMICAL SIERVAC1ES, ]INC.. 12 October 14, 2021 Project Number 182522-30A CONCRETE FLATWORK Thickness and Joint Spacing Concrete sidewalks and patio type slabs should be at least 31/2 inches thick and provided with construction or expansion joints every 6 feet or less, to reduce the potential for excessive cracking. Concrete driveway slabs should be at least 4 inches thick and provided with construction or expansion joints every 10 feet or less. Subgrade Preparation In order to reduce the potential for unsightly cracking, subgrade earth materials underlying concrete flatwork should be compacted to a minimum of 90 percent of the maximum dry density and then moistened to at least optimum or slightly above optimum moisture content. This moisture should extend to a minimum depth of 12 inches below subgrade and be maintained prior to placement of concrete. Pre- watering of the earth materials prior to placing concrete will promote uniform curing of the concrete and minimize the development of shrinkage cracks. The project geotechnical engineer or his representative should verify the density and moisture content of the earth materials and the depth of moisture penetration prior to placing concrete. Cracking within concrete flatwork is often a result of factors such as the use of too high a water to cement ratio and/or inadequate steps taken to prevent moisture loss during the curing of the concrete. Concrete distress can be reduced by proper concrete mix design and proper placement and curing of the concrete. Minor cracking within concrete flatwork is normal and should be expected. POST GRADING OBSERVATIONS AND TESTING It is the property owner's sole responsibility to notify Earth Strata Geotechnical Services at the appropriate times for observation and testing services. Earth Strata Geotechnical Services can not be responsible for any geotechnical recommendations where the appropriate observations and testing have not been performed. It is of the utmost importance that the owner or their representative request observations and testing for at least the following phases of work. Structure Construction • Observe all foundation excavations prior to placement of concrete or steel to verify adequate depth and competent bearing conditions. • If necessary, re-observe all foundation excavations after deficiencies have been corrected. Retaining Wall Construction • Observe all foundation excavations prior to placement of concrete or steel to verify adequate depth and competent bearing conditions. • If necessary, re-observe all foundation excavations after deficiencies have been corrected. ]EARTH STRATA G1E01FIEC1HIN11CAL SIERVAC1ES, ]INC.. 13 October 14, 2021 Project Number 182522-30A Observe and verify proper installation of subdrain systems prior to placing retaining wall backfill. Observe and test retaining wall backfill operations. Garden Walls Observe all foundation excavations prior to placement of concrete or steel to verify adequate depth and competent bearing conditions. If necessary, re-observe all foundation excavations after deficiencies have been corrected. Exterior Concrete Flatwork Construction Observe and test subgrade earth materials below all concrete flatwork to verify recommended density and moisture content. Utility Trench Backfill Observe and test all utility trench backfill operations. Re-Grading Observe and test the placement of any additional fill materials placed onsite. GRADING AND CONSTRUCTION RESPONSIBILITY It is the responsibility of the contractor or his subcontractors to meet or exceed the project specifications for grading and construction. The responsibilities of Earth Strata Geotechnical Services did not include the supervision or direction of the contractor's personnel, equipment, or subcontractors performing the actual work. Our field representative onsite was intended to provide the owner with professional advice, opinions, and recommendations based on observations and limited testing of the contractor's work. Our services do not relieve the contractor or his subcontractors of their responsibility, should defects in their work be discovered. The conclusions and recommendations herein are based on the observations and test results for the areas tested, and represent our engineering opinion as to the contractor's compliance with the project specifications. IEAIMMI SMR A' FA G1EMFIEC1HN111CA1L SIEIE N11C1ES, ]INC.. 14 October 14, 2021 Project Number 182522-30A REPORT LIMITATIONS This report has not been prepared for use by parties or projects other than those named or described herein. This report may not contain sufficient information for other parties or other purposes. Our services were performed using the degree of care and skill ordinarily exercised, under similar circumstances, by reputable soils engineers and geologists, practicing at the time and location this report was prepared. No other warranty, expressed or implied, is made as to the conclusions and professional advice included in this report. Earth materials vary in type, strength, and other geotechnical properties between points of observation and testing. Groundwater and moisture conditions can also vary due to natural processes or the works of man on this or adjacent properties. This report was prepared with the understanding that it is the responsibility of the owner or their representative, to ensure that the conclusions and recommendations contained herein are brought to the attention of the other project consultants and are incorporated into the plans and specifications. The owners' contractor should properly implement the conclusions and recommendations during construction and notify the owner if they consider any of the recommendations presented herein to be unsafe or unsuitable. Earth Strata Geotechnical Services sincerely appreciates the opportunity to provide our services and advice on this project. Respectfully presented, 1EA]UF1H( slr]KA\ FA GIE01FIECHIN11 CA IL SIEIKVI[C1ES, INC.. le oFESStp� SteStephen M. Poole, PE, G ro 4 p 0 No. 692 o M Principal Engineer uw W. 1r1P SMP/jmr s jgr�arEcvol- d Attachments: Appendix A- Re FDe��y�F Appendix B - Laboratory rocedures and Test Results Table 1 - Summary of Field Density Tests Plate 1 -As-Graded Geotechnical Map Distribution: (4) Addressee ]EARTH STRATA A TA\ G]E07117IEC]HIMI CA\IL S]ERVI(C1ES, ]INC. 15 October 14, 2021 Project Number 182522-30A APPENDIX REFERENCES APPENDIX A REFERENCES California Building Standards Commission, 2019, 2019 California Building Code, California Code of Regulations Title 24, Part 2, Volume 2 of 2, Based on 2012 International Building Code. National Association of Corrosion Engineers, 1984, Corrosion Basics An Introduction, page 191. Southern California Earthquake Center (SCEC), 1999, Recommended Procedures for Implementation of DMG Special Publication 117, Guidelines for Analyzing and Mitigating Liquefaction Hazards in California, March. APPENDIX B LABORATORY PROCEDURES AND TEST RESULTS APPENDIX B Laboratory Procedures and Test Results Laboratory testing provided quantitative and qualitative data involving the relevant engineering properties of the representative earth materials selected for testing. The representative samples were tested in general accordance with American Society for Testing and Materials (ASTM) procedures and/or California Test Methods (CTM). Soil Classification: Earth materials encountered during exploration were classified and logged in general accordance with the Standard Practice for Description and Identification of Soils (Visual- Manual Procedure) of ASTM D 2488. Upon completion of laboratory testing sample descriptions were reconciled to reflect laboratory test results with regard to ASTM D 2487. Maximum Densi , Tests: The maximum dry density and optimum moisture content of representative samples were determined using the guidelines of ASTM D 1557. The test results are presented in the table below. SAMPLE MATERIAL MAXIMUM DRY OPTIMUM MOISTURE NUMBER DESCRIPTION DENSITY(pcf) CONTENT(%) S-1 Silty SAND 128.5 11.0 S-2 Silty SAND 124.5 13.0 S-3 Silty SAND 127.5 11.0 S-4 Silty SAND 126.0 13.0 A13-1 Aggregate Base 146.5 6.5 Expansion Index: The expansion potential of representative samples was evaluated using the guidelines of ASTM D 4829. The test results are presented in the table below. SAMPLE MATERIAL EXPANSION INDEX EXPANSION POTENTIAL NUMBER DESCRIPTION S-3 Silty SAND 15 Very Low Minimum Resistivity and pH Tests: Minimum resistivity and pH tests of select samples were performed using the guidelines of CTM 643. The test results are presented in the table below. SAMPLE MATERIAL MINIMUM RESISTIVITY NUMBER DESCRIPTION PH (ohm-cm) S-1 Silty SAND 7.5 2,900 Soluble Sulfate: The soluble sulfate content of select samples was determined using the guidelines of CTM 417. The test results are presented in the table below. SAMPLE MATERIAL SULFATE CONTENT NUMBER DESCRIPTION (%by weight) SULFATE EXPOSURE S-1 Silty SAND 0.006 Negligible Chloride Content: Chloride content of select samples was determined using the guidelines of CTM 422. The test results are presented in the table below. SAMPLE NUMBER MATERIAL DESCRIPTION CHLORIDE CONTENT (ppm) S-1 Silty SAND 210 TABLE 1 SUMMARY OF FIELD DENSITY TESTS - ROUGH GRADE Test Test Test Test Depth Soil Dry Moisture Max. Rel. Test Location Density Content Density Density No. Type Date of (feet) Type (pcf) (%) (pcf) (%) 1 N 02/10/21 NG Middle of Store Pad -10 1 117.2 8.4 128.5 91 2 N 02/12/21 CF Middle of Store Pad -8 1 117.5 12.8 128.5 91 3 N 02/12/21 CF Middle of Pad -6 2 113.0 10.2 124.5 91 4 N 02/13/21 CF Southeast Corner -4 2 121.3 8.0 124.5 97 5 N 02/13/21 CF Southwest Corner -4 2 112.2 8.3 124.5 90 6 N 02/13/21 CF Northwest Corner -2 2 119.7 7.0 124.5 96 7 N 02/13/21 CF Northeast Corner -2 2 115.9 8.2 124.5 93 8 N 02/15/21 CF Southeast End of Gas Canopy -4 2 118.5 5.9 124.5 95 9 N 02/16/21 CF Southwest End of Gas Canopy -4 2 117.0 4.4 124.5 94 10 N 02/16/21 CF Northwest Corner of Gas Canopy -4 2 107.0 8.8 124.5 86 11 N 02/16/21 CF Retest of Test#10 -4 2 112.8 10.1 124.5 91 12 N 02/16/21 CF Northwest End of C-Store Pad FG 2 114.5 7.3 124.5 92 13 N 02/18/21 CF Northeast Corner of Gas Canopy FG 2 112.1 3.3 124.5 90 14 N 02/18/21 CF Southwest Corner of Gas Canopy FG 2 123.4 7.5 124.5 99 15 N 02/18/21 CF Southwest Drive Approach FG 2 112.1 6.5 124.5 90 16 N 02/18/21 CF Middle Drive Approach FG 2 112.2 10.4 124.5 90 N - Nuclear Test Method FG - Finish Grade Project No.: 18-2522-30A CF - Compacted Fill October 2021 LEGEND Locations are Approximate ROUGH GRADE Geologic Units Qyf - Quaternary Young Alluvial Fan Deposits Khg - Cretaceous Heterogeneous Granitics N. MAIN STREET (Circled Where Buried) A— Symbols Limits of Report 1 t 1 1 8 • - Boring Location Including Total Depth and Depth to Groundwater ROW DEDICATION" o '300' ROW DEDICATION x x x X X X X X X P 36 36' a— rn � 5-7' Recommended Removal Depths m p MONUMENT 16 �A( in PRICE SI AN � o DRAINAGE � ESCAPE LANE �— PYLON Canopy Pads,and Gas Tank / � � 4 BIOSVVALE SIGN P DRAINAGE BIO-)V11ALf= o ( WASH CAR UNDERGROUND o o Recommended Removal Depths Q STORAGE TANKS — — — — — — —10 1,125 SF 12' 5' in Parking Lot (� F• � • • • q 5_70 0 13 0 49' • 10' ? o 0 8 O O ® b Q i I e MPS _ 00 _ 1 1 5-71 (Q • �s 5' 36' 121' 35' 7 3,0Q* SF Z Q 20'rn ' l �- 5 • 3 GEOTECHNICAL MAP O • S 4 LOCATED ON THE NORTHEAST CORNER OF NORTH MAIN STREET AND WEST FLINT STREET CITY OF LAKE ELSINORE, RIVERSIDE COUNTY, CALIFORNIA — r r 1 APN 377-243-002 THROUGH 377-243-007 � fV • > • > • PROJECT CONVENIENCE STORE& CAR WASH CLIENT HARDESTY&ASSOCIATES PROJECT NO. 18-2522-30A DATE OCTOBER 28, 2021 SCALE 1:30 DWG XREFS REVISION DRAWN BY JDG IPLATE 1 OF 1 —M Earth Strata Geotechnical Services, Inco Geotechnical,Environmental and Materials Testing Consultants www.ESGSINC.com (951)397-8315