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HomeMy WebLinkAboutPD 2018-0022; KENNY RESIDENCE; FINAL SOILS REPORT; 2019-04-09▫ CW Soils, 23251 Kent Court, Murrieta, CA 92562 ▫ 951-304-3935 ▫ GEOTECHNICAL FINAL INTERPRETIVE AS GRADED REPORT PROPOSED KENNY RESIDENCE ASSESSOR’S PARCEL NUMBER 216-650-63-00 LOCATED ON VISTOSA PLACE, CITY OF CARLSBAD SAN DIEGO COUNTY, CALIFORNIA PROJECT NO. 18694-30 APRIL 9, 2019 CW SOILS 23251 Kent Court Murrieta, CA 92562 ▫ 951-304-3935 ▫ ▫ cwsoils.com ▫ April 9, 2019 CW SOILS April 9, 2019 Project No. 19758-30 Gerry and Liz Kenny 8009 Paseo Arrayan Carlsbad, CA 92009 Subject: Geotechnical Interpretive Rough Grade Report, Proposed Kenny Residence, Assessor’s Parcel Number 216-650-63-00, Located on Vistosa Place, City of Carlsbad, San Diego County, California INTRODUCTION Per your authorization, CW Soils has provided observation and testing services during rough grading for the proposed Kenny Residence, Assessor’s Parcel Number 216-650-63-00, located on Vistosa Place in the City of Carlsbad, San Diego County, California. This report summarizes the geotechnical conditions observed and tested during rough grading operations. We have provided conclusions and recommendations with regard to the suitability of the grading operations for the proposed project. Foundation design recommendations based on the soils present upon completion of grading have been presented herein. Grading operations commenced in order to develop one building pad for construction of a one- and/or two-story structure. The proposed improvements will consist of a single family residence utilizing slab on grade, wood, concrete, or steel-framed construction. Grading operations began in April 2019 and were completed in April 2019. REGULATORY COMPLIANCE Observations and selective testing have been performed by representatives of CW Soils during the grading operations. Our services were performed in general accordance with the recommendations presented in the referenced reports (see References), the grading code of the appropriate reviewing agency, and as dictated by conditions encountered in the field. The earthwork testing and observations described herein have been reviewed and are considered adequate for the planned construction. 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. ENGINEERING GEOLOGY Geologic Units Soils noted during grading operations included bedrock. April 9, 2019 CW SOILS Groundwater Groundwater was not encountered during grading operations. Faulting Significant faulting was not observed during grading operations. EARTHWORK OBSERVATIONS AND DENSITY TESTING Site Clearing and Grubbing Prior to grading operations, all trees, brush, and shrubs were stripped and removed from the compacted fill. Ground Preparation Remedial removals were roughly less than 6 inches below original grades, with locally deeper removals. Prior to placing compacted fill, the exposed bottom surfaces were watered or air dried as necessary to achieve near optimum moisture content and then compacted to a minimum of 90 percent of the maximum dry density per ASTM D1557. Oversize Rock During the grading operations, rock greater than 1 foot in maximum dimension, oversize rock, was not generally encountered. Fill Placement and Testing Fills were placed in lifts on the order of 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, rubber tired dozer, sheepsfoot, and/or loaded scrapers. The maximum vertical depth of compacted fill within the proposed building pads is on the order of 6 inches. Field density and moisture content tests utilizing nuclear gauge methods were performed in accordance with ASTM Test Methods D2922 and D3017. Visual classification of the soils in the field was the basis for determining which maximum dry density value was applicable for individual density tests. The 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. 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 desired minimum density had been 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. April 9, 2019 CW SOILS LABORATORY TESTING Maximum Dry Density Maximum dry density and optimum moisture content for representative soils noted during grading operations were determined using the guidelines of ASTM Test Method D 1557-12. Pertinent test values are summarized in Appendix B. Expansion Index Tests Expansion index tests were performed on representative soils sampled near finish grade for select building pads using the guidelines of ASTM D 4829-03. Test results are summarized in Appendix B. Soluble Sulfate Analyses The soluble sulfate content of soils was determined using the guidelines of California Test Method (CTM) 417. Test results are summarized in Appendix B. Chloride Chloride content of soils 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 soils were determined using the guidelines of CTM 643. Test results are summarized in Appendix B. POST GRADING CONSIDERATIONS Slope Landscaping and Maintenance Provided all drainage provisions are properly constructed and maintained, the gross stability of graded slopes should not be adversely affected. However, satisfactory slope and building pad drainage is essential for the long term performance of the site. Concentrated drainage should not be allowed to flow uncontrolled over any descending slope. As recommended by the project landscape architect, engineered slopes should be landscaped with deep rooted, drought tolerant maintenance free plant species. Site Drainage Maintaining control over drainage throughout the site is important for the long term performance of the proposed improvements. We recommend roof gutters or equivalent roof collection system for proposed structures. Pad and roof drainage should be routed in non-erosive drainage devices to driveways, adjacent streets, storm-drain facilities, or other locations approved by the building official. Drainage should not be allowed to pond on the building pad or near any foundations. Planters located within retaining wall backfill should be sealed to prevent moisture intrusion into the backfill. Planters located next to structures April 9, 2019 CW SOILS should be sealed to the depth of the footings. Drainage control devices require periodic cleaning, testing and maintenance to remain effective. Building pad drainage should be designed to meet the minimum gradient requirements of the CBC, to divert water away from foundations. Utility Trenches All utility trench backfill should be compacted at near optimum moisture to a minimum of 90 percent of the maximum dry density as determined by ASTM D1557-12. Trench backfill should be placed in approximately 6 to 8 inch maximum loose lifts and then mechanically compacted with a hydro-hammer, a sheepsfoot, pneumatic tampers, or similar equipment. Within pavement areas, the upper 6 inches of subgrade materials for utility trench backfill should be compacted to 95 percent of the maximum dry density determined by ASTM D1557-12. The utility trench backfill should be observed and tested by the project soils engineer or their representative to verify that the minimum compaction requirements have been obtained. Where utility trenches undercut perimeter foundations, all utility trenches should be backfilled with compacted fill, lean concrete or concrete slurry to minimize the penetration of moisture below building slabs. When practical, interior or exterior utility trenches that run parallel to structure footings should not be located within a 1:1 (h:v) plane projected downward from the outside bottom edge of the footing. FOUNDATION DESIGN RECOMMENDATIONS General Shallow foundations are considered feasible for support of the proposed structure, provided construction is performed in accordance with the recommendations of this report. Foundation recommendations are provided in the following sections. Allowable Bearing Values An allowable bearing value of 2,000 pounds per square foot (psf) is recommended for design of 12 inch wide continuous footings founded at a minimum depth of 12 inches below the lowest adjacent final grade and 24 inch square pad footings. 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 We estimate that the maximum total settlement of the footings will be less than approximately ¾ inch, based on the anticipated loading and the settlement characteristics of the underling earth materials. Differential settlement is expected to be about ½ inch over a horizontal distance of approximately 20 feet, for an angular distortion ratio of 1:480. The majority of the settlement is anticipated to occur during construction or shortly after the initial application of loading. April 9, 2019 CW SOILS The above settlement estimates are based on the assumption that the grading and construction are performed in accordance with the recommendations presented in this report. Additionally, the project soils consultant or his representative will be provided the opportunity to observe the foundation 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 soils to determine lateral sliding resistance. 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. Expansive Soil Considerations The laboratory test results indicate that the onsite soils exhibit an expansion potential of VERY LOW as classified by the 2016 CBC Section 1803.5.3 and ASTM D4829-03. However, the preliminary soils report encountered soils that exhibit an expansion potential of LOW (CW Soils, 2018). As a result, recommendations for LOW are provided herein. The following recommendations should be considered the very minimum requirements, for the soils tested. It is common practice for the project architect or structural engineer to require additional slab thickness, footing sizes, and/or reinforcement. Low Expansion Potential (Expansion Index of 21 to 50) Our laboratory test results indicate that the soils onsite exhibit a LOW expansion potential as classified by the 2016 CBC Section 1803.5.3 and ASTM D4829-03. As such, the CBC specifies that slab on grade foundations (floor slabs) resting on soils with expansion indices greater than 20, require special design considerations per the 2016 CBC Sections 1808.6.1 and 1808.6.2. The design procedures incorporate the thickness and plasticity index of the various soils within the upper 15 feet of the proposed structure. We have assumed an effective plasticity index of 12, for preliminary design purposes. Conventional Footings • Exterior continuous footings should be founded at the minimum depths below the lowest adjacent final grade (i.e. minimum 12 inch depth for one-story, minimum 18 inch depth for two-story, and minimum 24 inch 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. In accordance with Table 1809.7 of the 2016 CBC, all continuous footings should have a minimum width of 12, 15, and 18 inches, for one-, two-, and three-story structures, respectively, 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. The pad footings should be reinforced with a minimum April 9, 2019 CW SOILS of No. 4 bars spaced a maximum of 18 inches on center, each way, and should be placed near the bottom-third of the footings. Building Floor Slabs • Building floor slabs should be a minimum of 4 inches thick. All floor slabs should be reinforced with a minimum of No. 3 bars spaced a maximum of 18 inches on center, each way, supported by concrete chairs or bricks to ensure desired mid-depth placement. Based on an assumed effective plasticity index of 12, the project architect or structural engineer should evaluate minimum floor slab thickness and reinforcement in accordance with 2016 CBC Section 1808.6.2. • Building floor slabs with moisture sensitive or occupied areas, should be underlain by a minimum 10- mil thick moisture barrier to help reduce the upward migration of moisture from the underlying soils. The moisture barrier should be properly installed using the guidelines of ACI publication 318-05 and meet the performance standards of ASTM E 1745 Class A material. Prior to placing concrete, it is the responsibility of the contractor to ensure that the moisture barrier is properly placed and free of openings, rips, or punctures. As an option for additional moisture protection and foundation strength, higher strength concrete, such as a minimum compressive strength of 5,000 pounds per square inch (psi) in 28-days may be used. In addition, a capillary break/vapor retarder for concrete slabs should be provided in accordance with CALGreen. Ultimately, the design of the moisture barrier system along with recommendations for concrete placement and curing are the purview of the foundation engineer, factoring in the project conditions 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 ⅜ 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. • Prior to placing concrete, the subgrade soils below all floor slabs should be pre-watered to achieve a moisture content that is at least equal or slightly greater than optimum moisture content. The moisture content should penetrate a minimum depth of 6 inches into the subgrade soils. The pre-watering should be verified by CW Soils during construction. Post Tensioned Slab/Foundation Design Recommendations In lieu of the proceeding foundation recommendations, post tensioned slabs may be used for the proposed structures. Post tension foundations are generally considered to be a better foundation system, but may be slightly higher in overall cost. The foundation engineer may design the post tensioned foundation system using the following Post Tensioned Foundation Slab Design table. These parameters have been provided in general accordance with Post Tensioned Design. Alternate designs addressing the effects of expansive soils are allowed per 2016 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. It should be noted that the post tensioned design methodology is partially based on the assumption that soils moisture changes around and underneath post tensioned slabs, are only influenced by climate conditions. With regard to expansive soils, moisture variations below slabs are the major factor in foundation damage. However, the design methodology does not take into account presaturation, owner irrigation, or other non-climate related April 9, 2019 CW SOILS influences on the moisture content of the subgrade soils. In recognition of these realities, we modified the soils parameters obtained from this methodology to help account for reasonable irrigation practices. Additionally, the slab subgrades should be presoaked to a depth of 12 inches and maintained at above optimum moisture until placing concrete. Furthermore, prior to placing concrete, the subgrade soils below all floor slabs and perimeter footings should be presoaked to achieve moisture contents at least 1.0, 1.1, 1.2, and 1.3 times optimum to depths of 6, 12, 18, and 24 inches for Low, Medium, High, and Very High expansion potential soils, respectively. The moisture content should penetrate to a minimum depth of 24 inches into the subgrade soils. The pre-watering should be verified and tested by CW Soils. Ponding water near the foundation can significantly change the moisture content of the soils below the foundation, causing excessive foundation movement and detrimental effects. Our recommendations do not account for excessive irrigation and/or incorrect landscape designs. To prevent moisture infiltration below the foundation, planters placed adjacent to the foundation should be designed with an effective drainage system or liners. Some lifting of the perimeter foundation should be expected even with properly constructed planters. Future owners should be informed and educated of the importance in maintaining a consistent level of moisture within the soils around structures. Potential negative consequences can result from either excessive watering or allowing expansive soils to become too dry. Expansive soils will shrink as they dry, followed by swelling during the rainy winter season or when irrigation is resumed, causing distress to site improvements. Post Tensioned Foundation Slab Design PARAMETER VALUE Expansion Index Low1 Percent Finer than 0.002 mm in the Fraction Passing the No. 200 Sieve < 20 percent (assumed) Clay Mineral Type Montmorillonite (assumed) Thornthwaite Moisture Index -20 Depth to Constant Soil Suction 7 feet Constant Soil Suction P.F. 3.6 Moisture Velocity 0.7 inch/month Center Lift Edge moisture variation distance, em Center lift, ym 5.5 feet 2.0 inches Edge Lift Edge moisture variation distance, em Edge lift, ym 3.0 feet 0.8 inches Soluble Sulfate Content for Design of Concrete Mixtures in Contact with Soils Negligible Modulus of Subgrade Reaction, k (assuming presaturation as indicated below) 200 pci Minimum Perimeter Foundation Embedment 12 Perimeter Foundation Reinforcement -- Under Slab Moisture Barrier and Sand Layer 10-mil thick moisture barrier meeting the requirements of a ASTM E 1745 Class A material 1. Assumed for design purposes or obtained by laboratory testing. 2. Recommendations for foundation reinforcement are ultimately the purview of the foundation/structural engineer based upon the soils criteria presented in this report and structural engineering considerations. April 9, 2019 CW SOILS Foundation 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, in accordance with the 2016 CBC. The foundations should be excavated per the approved plans, moistened, cleaned of all loose materials, trimmed neat, level, and square. Moisture softened soils should be removed prior to steel or concrete placement. Soils from foundation excavations should be removed from slab on grade areas, unless they have been properly compacted and tested. 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 soils engineering point of view, the “substances” are the reinforced concrete foundations or buried metallic elements (not surrounded by concrete) and the “environment” is the prevailing soils in contact with them. Many factors can contribute to corrosivity, including the presence of chlorides, sulfates, salts, organic materials, different oxygen levels, poor drainage, varying soils consistencies, and moisture content. It is not considered practical or realistic to test for all of the factors which may contribute to corrosivity. The level of chlorides considered to be significantly detrimental to concrete is based upon the industry recognized Caltrans standard “Bridge Design Specifications”. Under subsection 8.22.1 of that document, Caltrans established that “Corrosive water or soil contains more than 500 parts per million (ppm) of chlorides”. Based on limited testing, the onsite soils tested have chloride contents less than 500 ppm. Therefore, specific requirements resulting from elevated chloride contents are not required. When the soluble sulfate content of soils exceeds 0.1 percent by weight, specific guidelines for concrete mix design are provided in the 2016 CBC Section 1904 and in ACI 318, Section 4.3 Table 4.3.1. Based on limited testing, the onsite soils are classified as having a negligible (less than 0.10 % by weight) sulfate exposure condition, in accordance with Table 4.3.1. Therefore, structural concrete in contact with onsite soils should utilize Type I or II. The onsite soils in contact with buried steel should be considered moderately (1,000 to 2,000 Ohms-cm) corrosive based on our laboratory testing of resistivity. Additionally, pH values below 9.7 are recognized as being corrosive to most common metallic components including, copper, steel, iron, and aluminum. The pH values for the soils tested were lower than 9.7. Therefore, any steel or metallic materials that are exposed to the soils should be encased in concrete or other remedies applied to provide corrosion protection. It should be noted that CW Soils are not corrosion engineers and the test results for corrosivity are based on limited samples thought to be representative. Laboratory test results are presented in Appendix B. EXTERIOR CONCRETE Subgrade Preparation Subgrade soils underlying concrete flatwork should be compacted at near optimum moisture to a minimum of 90 percent of the maximum dry density as determined by ASTM test method D1557-12. Prior to placing concrete, the subgrade soils should be moistened to at least optimum or slightly above optimum moisture content (see table below). Pre-watering of the soils prior to placing concrete will promote uniform curing of the concrete and April 9, 2019 CW SOILS minimize the development of shrinkage cracks. The higher the expansion potential of the onsite soils the longer it will take to achieve the recommended presaturation. Therefore, the procedure and timing should be planned in advance. The project soils engineer or his representative should verify the density and moisture content of the soils prior to placing concrete. Flatwork Design Cracking within concrete flatwork is often a result of factors such as the use of too high of a water to cement ratio and/or inadequate steps taken to prevent moisture loss during the curing of the concrete. However, minor cracking within concrete flatwork is normal and should be expected. It should be noted that the reduction of slab cracking is often a function of proper slab design, concrete mix design, placement, curing, and finishing practices. We recommend the adherence to the guidelines of the American Concrete Institute (ACI). When placed over expansive soils, exterior concrete elements are susceptible to lifting and cracking. When this occurs with highly expansive soils, the detrimental impacts can be significant and may necessitate the removal and replacement of the affected improvements. In order to reduce the potential for unsightly cracking, we suggest a combination of presaturation of the subgrade soils, reinforcement, restraint, and a layer of granular materials. Although these measures may not completely eliminate distress to concrete improvements, the application of these measures can significantly reduce the distress caused by expansive soils. The degree and extent the measures recommended in the following table are applied depend on: • The expansion potential of the subgrade soils. • The practicality of implementing the measures (such as presaturation). • The benefits verse the economics of the measures. The project owner should perform a cost/benefit analysis on the factors to determine the extent the measures will be applied to each project. The expansive potential of the onsite soils should be considered LOW. CONCRETE FLATWORK CONSTRUCTION DESIGN EXPANSION INDEX VERY LOW LOW MEDIUM HIGH VERY HIGH Slab Thickness, Minimum 3.5 inches 3.5 inches 4 inches 4 inches 4.5 inches Subbase, Gravel Layer NA NA Optional 3 inches 4 inches Presaturation, Relative to Optimum Moisture Content Pre-wet NA Optimum 6 inches Deep 1.1 x Optimum 12 inches Deep 1.2 x Optimum 18 inches Deep 1.3 x Optimum 24 inches Deep Joint, Maximum Spacing, (joint to extend ¼ slab) 10 feet or less 10 feet or less 8 feet or less 6 feet or less 6 feet or less Reinforcement, Mid-Depth NA NA Optional (WWF 6 x 6 W1.4 x W1.4) No. 3 Rebar 24” On Center Both Ways No. 3 Rebar 24” On Center Both Ways Restraint, Slip Dowels Mid-Depth NA NA Optional Across Cold Joints Across Cold Joints The use of a granular layer for exterior slabs is primarily intended to facilitate presaturation and subsequent construction operations by providing a working surface over the saturated soils and to help retain the moisture. Where these factors are insignificant, the layer may be omitted. April 9, 2019 CW SOILS POST GRADING OBSERVATIONS AND TESTING It is the owner’s sole responsibility to timely notify CW Soils for observation and testing services. Where the appropriate observations and testing have not been performed, CW Soils can not be responsible for any geotechnical recommendations. It is of the utmost importance that the owner or their representative timely request observations and testing for at least the following phases of work. Structure Construction • Observe and/or test all foundation excavations prior to placement of concrete or steel to verify adequate depth and competent bearing conditions. • If necessary, re-observe and/or test all foundation excavations after deficiencies have been corrected. Exterior Concrete Flatwork Construction • Observe and test subgrade soils below all concrete flatwork to verify recommended density and moisture content. Utility Trench Backfill • Observe and test all utility trench backfill. Re-Grading • Observe and test the placement of any additional fill. GRADING AND CONSTRUCTION RESPONSIBILITY It is the responsibility of the contractor to meet or exceed the minimum project specifications for grading and construction. Our responsibilities did not include the supervision or direction of the contractor’s personnel, equipment, or subcontractors performing the actual grading and construction. Our field representative was intended to provide the owner with professional advice, opinions, test results, and recommendations based on observations and limited testing of the contractor’s work. If defects in the contractor’s work are discovered, our services do not relieve the contractor or his subcontractors of their responsibility. The conclusions and recommendations herein are based on the observations and test results for the areas tested, and represent our engineering opinion with regard to the contractor’s compliance with the project plans and specifications. REPORT LIMITATIONS This report has not been prepared for parties or projects other than those named or described herein. This report is not likely to 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 engineering and geologic professionals, 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 provided in this report. APPENDIX A REFERENCES APPENDIX A REFERENCES California Building Standards Commission, 2016, 2016 California Building Code, California Code of Regulations Title 24, Part 2, Volume 2 of 2, Based on 2015 International Building Code. C.W. Soils, Inc., Preliminary Geotechnical Interpretive Report, Proposed Kenny Residence, Assessor’s Parcel Number 216-650-63-00, Located on Vistosa Place, City of Carlsbad, San Diego County, California, dated November 2, 2018. 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 Our laboratory testing has provided quantitative and qualitative data involving the relevant engineering properties of the representative soils selected for testing. Representative samples were tested using the guidelines of the American Society for Testing and Materials (ASTM) procedures or California Test Methods (CTM). Soil Classification: The soils observed 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, exploratory logs and sample descriptions may have been reconciled to reflect laboratory test results with regard to ASTM D 2487. Maximum Density Tests: The maximum dry density and optimum moisture content of representative samples were determined using the guidelines of ASTM D1557. The test results are presented in the table below. SAMPLE NUMBER MATERIAL DESCRIPTION MAXIMUM DRY DENSITY (pcf) OPTIMUM MOISTURE CONTENT (%) E-1 Clayey SAND 117.0 14.5 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 NUMBER MATERIAL DESCRIPTION EXPANSION INDEX EXPANSION POTENTIAL E-1 Clayey SAND 8 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 NUMBER MATERIAL DESCRIPTION pH MINIMUM RESISTIVITY (ohm-cm) E-1 Clayey SAND 6.7 1,570 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 NUMBER MATERIAL DESCRIPTION SULFATE CONTENT (% by weight) SULFATE EXPOSURE E-1 Clayey SAND 0.030 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) E-1 Clayey SAND 360 I I I I I TABLE 1 SUMMARY OF FIELD DENSITY TESTS Test No.Test Type Test Date Test of Test Location Elevation (feet) Soil Type Dry Density (pcf) Moisture Content (%) Max. Density (pcf) Rel. Density (%) 1 N 04/05/19 CF Building Pad FG 1 106.5 14.0 117.0 91 2 N 04/05/19 CF Building Pad FG 1 110.6 13.9 117.0 95 N - Nuclear Test Method SC - Sand Cone Method SG - Subgrade FG - Finish Grade NG - Native Ground CF - Compacted Fill Project No.: 18694-30 REFERENCE: DMA, 2018, Site Plan, October 12, 2018. 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