geotechnical engineering investigation stockton …

ENVIRONMENTAL, GEOTECHNICAL, CONSTRUCTION SERVICES AND ANALYTICAL TESTING

GEOTECHNICAL ENGINEERING INVESTIGATIONSTOCKTON SOCCER COMPLEX PROJECT

STOCKTON, CALIFORNIA

BSK PROJECT G20-189-11S

PREPARED FOR:

SIEGFRIED ENGINEERING, INC.3244 BROOKSIDE ROAD, SUITE 100

STOCKTON, CALIFORNIA 95219

September 18, 2020

GEOTECHNICAL ENGINEERING INVESTIGATION REPORTSTOCKTON SOCCER COMPLEX PROJECTSTOCKTON, CALIFORNIA

Prepared for:

Ms. Mary Jane KabalinSiegfried Engineering, Inc.3244 Brookside Road, Suite 100Stockton, California 95219

Sacramento Project: G20-189-11S

September 18, 2020

Prepared by:

______________________________________Corinne Goodwin, PE #90559Project Engineer

______________________________________On Man Lau, PE, GE #2644Senior Geotechnical Engineer

BSK Associates3140 Gold Camp Drive #160Rancho Cordova, CA 95670(916) 853-9293(916) 853-9297 FAX

Distribution: Client (Email: [[email protected]])

Geotechnical Engineering Investigation Report BSK Project G20-189-11SStockton Soccer Complex Project September 18, 2020Stockton, California P a g e | i

Table of Contents1. Introduction .................................................................................................................................... 1

1.1. Planned Construction ............................................................................................................... 1

1.2. Purpose and Scope of Services ................................................................................................. 1

2. Field Investigation and Laboratory Testing ....................................................................................... 1

2.1. Field Exploration ...................................................................................................................... 1

2.2 Laboratory Testing ................................................................................................................... 2

3. Site and Geology/Seismicity Conditions ........................................................................................... 2

3.1 Site Description and Surface Conditions ................................................................................... 2

3.2 Regional Geology ..................................................................................................................... 2

3.2.1 Regional Geology .............................................................................................................. 2

3.2.2 Seismic Hazards Assessment ............................................................................................. 2

3.3 Subsurface Conditions .............................................................................................................. 3

3.4 Groundwater Conditions .......................................................................................................... 3

4. Conclusions and Recommendations ................................................................................................. 3

4.1 Seismic Design Criteria ............................................................................................................. 4

4.2 Soil Corrosivity ......................................................................................................................... 5

4.3 Site Preparation Recommendations ......................................................................................... 5

4.4 Foundations ............................................................................................................................. 7

4.4.1 Shallow Foundations ........................................................................................................ 7

4.4.2 Mat Foundations .............................................................................................................. 7

4.4.3 Pole-Type Foundations ..................................................................................................... 7

4.4.4 Pole-Type Foundation Considerations............................................................................... 7

4.5 Lateral Earth Pressures and Frictional Resistance ..................................................................... 8

4.6 Slab-On-Grade ......................................................................................................................... 9

4.7 Pavements ............................................................................................................................. 11

4.9 Excavation Stability ................................................................................................................ 12

4.10 Trench Backfill and Compaction ............................................................................................. 12

4.11 Drainage Considerations ........................................................................................................ 12

5. Plans and Specifications Review ..................................................................................................... 13

6. Construction Testing and Observations .......................................................................................... 13

7. Limitations ..................................................................................................................................... 13

Geotechnical Engineering Investigation Report BSK Project G20-189-11SStockton Soccer Complex Project September 18, 2020Stockton, California P a g e | ii

8. References ..................................................................................................................................... 14

TablesTable 1: Seismic Design ParametersTable 2: Recommended Static Lateral Earth Pressures for Footings

AppendicesAppendix A: Field ExplorationTable A-1: Apparent Relative Density Coarse-Grained Soil by Sampler Blow CountTable A-2: Consistency Fine-Grained Soil by Sampler Blow CountFigure A-1: Site Vicinity MapFigure A-2: Boring Location MapFigure A-3: Soil Classification Chart and Log KeyBoring Logs: Borings B-1 through B-5

Appendix B: Laboratory TestingTable B-1: Summary of Corrosion Test ResultsFigure B-1: Direct Shear Test ResultsFigure B-2: Expansion Index Test ResultsFigure B-3: R-Value Test ResultsFigure B-4: Plasticity Index Test Results

Geotechnical Engineering Investigation Report BSK Project G20-189-11SStockton Soccer Complex Project September 18, 2020Stockton, California P a g e | 1

1. INTRODUCTION

This report presents the results of a Geotechnical Engineering Investigation conducted by BSK Associates(BSK), for the Stockton Soccer Complex Upgrades in Stockton, California (Site). The Site is located in theexisting soccer complex at 10055 CA-99 in Stockton, California, as shown on the Site Vicinity Map, FigureA-1. The geotechnical engineering investigation was conducted in accordance with BSK Proposal GS20-20829, dated August 21, 2020.

This report provides a description of our site investigation methods and findings, including field andlaboratory data, the geotechnical conditions at the Site, and provides specific recommendations forearthwork and foundation design with respect to the planned structures.

1.1. Planned ConstructionBSK understands that improvements will consist of constructing a new restroom building and expandingthe parking lots at the existing Stockton Soccer Complex northwest of CA-99 and E Morada Lane inStockton, California. The scoreboards and gates will be founded on cast-in-place drilled piers. Additionalimprovements include a new playground, concrete paving for a food truck area, eight (8) sports fields,sports field lights, underground utilities, landscaping, concrete sidewalks and curbs, irrigation, and lightpoles.

In the event that significant changes occur in the design of the proposed improvements, this report’sconclusions and recommendations will not be considered valid unless the changes are reviewed with BSKand the conclusions and recommendations are modified or verified in writing.

1.2. Purpose and Scope of ServicesThe objective of this geotechnical investigation was to characterize the subsurface conditions in the areasof the proposed structures and provide geotechnical engineering recommendations for the preparationof plans and specifications and bearing and lateral earth pressure conditions. The scope of theinvestigation included a field exploration, laboratory testing, engineering analyses, and preparation of thisreport.

This investigation specifically excludes the assessment of site environmental characteristics, particularlythose involving hazardous substances.

2. FIELD INVESTIGATION AND LABORATORY TESTING

2.1. Field ExplorationThe field exploration for this investigation was conducted under the oversight of a BSK Engineer. Five (5)test borings were drilled at the site on September 1, 2020 by Baja Exploration using a CME 75 Drill Rig.The test borings were drilled to a maximum depth of approximately 36½ feet below existing groundsurface (bgs). A geotechnical boring permit was obtained from San Joaquin County Department ofEnvironmental Health. A discussion of the details of the field exploration is provided in Appendix A.


2.2 Laboratory TestingLaboratory tests were performed on selected soil samples to evaluate moisture content, dry density, shearstrength, expansion potential, R-Value, Atterberg limits, and corrosion characteristics. A description of thelaboratory test methods and results are presented in Appendix B.

3. SITE AND GEOLOGY/SEISMICITY CONDITIONS

The following sections address the Site description and surface conditions, regional geology and seismichazards, subsurface conditions, and groundwater conditions at the Site. This information is based on BSK’sfield exploration and published maps and reports.

3.1 Site Description and Surface ConditionsThe Site is located at the existing Stockton Soccer Complex. The ground surface was paved with asphaltconcrete in the parking lots and gravel in the northwest corner of the site near a transformer. The site islocated in the southeast quarter of Section 1, Township 2 North, Range 6 East of the Mount DiabloMeridian. The NAD 83 GPS coordinates for the center of the Site are 38.0451 degrees North latitude and121.2610 degrees West longitude. The site is at an elevation ranging from 15 to 41 feet mean seal level(msl).

3.2 Regional GeologyOur scope of services included a review of published maps and reports to assess the regional geology andpotential for seismic hazards.

3.2.1 Regional GeologyThe Great Valley is an alluvial plain about 50 miles wide and 400 miles long in the central part of California.Its northern part is the Sacramento Valley, drained by the Sacramento River and its southern part is theSan Joaquin Valley drained by the San Joaquin River. The Great Valley is a trough in which sediments havebeen deposited almost continuously since the Jurassic (about 160 million years ago). Great oil fields havebeen found in southernmost San Joaquin Valley and along anticlinal uplifts on its southwestern margin. Inthe Sacramento Valley, the Sutter Buttes, the remnants of an isolated Pliocene volcano, rise above thevalley floor.

3.2.2 Seismic Hazards AssessmentThe types of geologic and seismic hazards assessed include surface ground fault rupture, liquefaction,seismically induced settlement, slope failure, flood hazards and inundation hazards.

The purpose of the Alquist-Priolo Geologic Hazards Zones Act, as summarized in CDMG Special Publication42 (SP 42), is to "prohibit the location of most structures for human occupancy across the traces of activefaults and to mitigate thereby the hazard of fault-rupture." As indicated by SP 42, "the State Geologist isrequired to delineate "earthquake fault zones" (EFZs) along known active faults in California. Cities andcounties affected by the zones must regulate certain development 'projects' within the zones. They mustwithhold development permits for sites within the zones until geologic investigations demonstrate thatthe sites are not threatened by surface displacement from future faulting.


The site is not located in an Alquist-Priolo (AP) Earthquake Fault Zone. The closest faults are the FoothillsFault zone about 26 miles northeast of the site and the Midway fault about 28 miles southwest of the site.The closest AP fault zone is associated with the Greenville fault about 33 miles southwest of the site. Weexpect the site to be subjected to moderate ground shaking due to a major seismic event in thesurrounding regions during the design life of the project.

Zones of Required Investigation referred to as "Seismic Hazard Zones" in CCR Article 10, Section 3722, areareas shown on Seismic Hazard Zone Maps where site investigations are required to determine the needfor mitigation of potential liquefaction and/or earthquake-induced landslide ground displacements.

The Site is not located in a Liquefaction or Landslide Seismic Hazard Zone specified by the State ofCalifornia. Additionally, the potential for liquefaction is low because of the deep groundwater level andclayey soil.

3.3 Subsurface ConditionsThe subsurface material generally consisted of sandy and silty lean clays with medium plasticity underlainby layers of sandy clay, clayey sand and poorly graded sand to the maximum depth of exploration of 3 to36½ feet bgs.

The upper 5 feet of on-site soil is considered to have a medium expansion potential with an expansionindex of 51 at Boring B-3.

The boring logs in Appendix A provide a more detailed description of the materials encountered, includingthe applicable Unified Soil Classification System symbols.

It should be noted that soil and subsurface conditions can deviate from those conditions encountered atthe boring locations. If significant variation in the subsurface conditions is encountered duringconstruction, it may be necessary for BSK to review the recommendations presented herein andrecommend adjustments, as necessary.

3.4 Groundwater ConditionsGroundwater was not encountered at the time of drilling on September 1, 2020. Based on thegroundwater elevation data from the California Department of Water Resources (DWR), the historic highgroundwater depth in the vicinity was recorded to be approximately 70 feet bgs.

Please note that the groundwater level may fluctuate both seasonally and from year to year due tovariations in rainfall, temperature, pumping from wells and possibly as the result of other factors such asirrigation, that were not evident at the time of our investigation.

4. CONCLUSIONS AND RECOMMENDATIONS

Based upon the data collected during this investigation, and from a geotechnical engineering standpoint,it is our opinion that the soil conditions would not preclude the construction of the proposed


improvements. The main geotechnical concern for the project Site is the presence of moderatelyexpansive soils.

The proposed improvements may be supported on shallow or mat foundations and pole-type pierfoundations, provided the footings are deepened or the soils underlying the footings is excavated andrecompacted to reduce the collapse potential. Recommendations are provided in the sections below tomitigate this geotechnical concern.

4.1 Seismic Design CriteriaBased on Section 1613.2.2 of the 2019 California Building Code (CBC), the Site shall be classified as SiteClass A, B, C, D, E or F based on the Site soil properties and in accordance with Chapter 20 of ASCE 7-16.Based on the data from the test borings, as per Table 20.3-1 of ASCE 7-16, the Site is Class D (15 ≤ N ≤ 50).

The 2019 CBC utilizes ground motion based on the Risk-Targeted Maximum Considered Earthquake(MCER) that is defined in the 2019 CBC as the most severe earthquake effects considered by this code,determined for the orientation that results in the largest maximum response to horizontal ground motionsand with adjustment for targeted risk. Ground motion parameters in the 2019 CBC are based on ASCE 7-16, Chapter 11.

The Structural Engineers Associates of California (SEAOC) has prepared maps presenting the Risk-TargetedMCE spectral acceleration (5 percent damping) for periods of 0.2 seconds (SS) and 1.0 seconds (S1). Thevalues of SS and S1 can be obtained from the Occupational Safety Health Planning and Development(OSHPD) Seismic Design Maps Tool at: https://seismicmaps.org/.

The OSHPD Seismic Design Maps Tool and Chapter 16 of the 2019 CBC based on ASCE 7-16 produced thespectral acceleration parameters risk targeted maximum considered earthquake values in Table 1 basedon Site Class D conditions.

As per Section 1803.5.12 of the 2019 CBC, peak ground acceleration (PGA) utilized for dynamic lateralearth pressures and liquefaction, shall be based on a site-specific study (ASCE 7-16, Section 21.5) or ASCE7-16, Section 11.8.3. The OSHPD Seismic Design Maps Tool and based on ASCE 7-16, Section 11.8.3produced the Geometric Mean PGA value in Table 1 based on Site Class D conditions.


Table 1: Seismic Design Parameters

Seismic Design Parameter 2019 CBC Value Reference

MCE Mapped Spectral Acceleration(g) SS = 0.650 S1 = 0.265 USGS Mapped Value

Amplification Factors (Site Class D) Fa = 1.280 Fv = null1(2.070)2 ASCE Table 11.4

Site Adjusted MCE SpectralAcceleration (g) SMS = 0.832 SM1 = null1(0.549)2 ASCE Equations 11.4.1-2

Design Spectral Acceleration (g) SDS = 0.555 SD1 = null1 (0.366)2 ASCE Equations 11.4.1-4

Geometric Mean PGA (g) PGAM = 0.361 Section 11.8.3, ASCE 7-16

Site Short Period – Ts (seconds) Ts = 0.659 Ts = SD1/ SDS

Site Long Period – TL (seconds) TL = 12 USGS Mapped Value

Notes: 1 Requires site-specific ground motion procedure or exception as per ASCE 7-16 Section 11.4.82 Values from ASCE 7-16 supplement, shall only be used to calculate Ts

4.2 Soil CorrosivityA surface soil sample obtained from the Site were tested to provide a preliminary screening of thepotential for concrete deterioration or steel corrosion due to attack by soil-borne soluble salts. The testresults are presented in Appendix B.

The corrosivity evaluation was performed by BSK on a composite soil sample from B-3 in the upper 5 feetobtained at the time of drilling. The soil was evaluated for pH (ASTM D4972), and soluble sulfate andchlorides (CT 417 and CT 422). The sample has a minimum resistivity of 2,140, pH is 8.5, sulfate is 10mg/kg, and chloride was not detected.

The water-soluble sulfate content severity class is considered not severe to concrete (Exposure CategoryS0 per Table 4.2.1 of ACI 318-11). The site soils minimum resistivity is considered moderately corrosive toburied metal per ASTM G187. Therefore, buried metal conduits, ferrous metal pipes, and exposed steelshould have a protective coating in accordance with the manufacturer’s specification. The above aregeneral discussions. A more detailed investigation may include more or fewer concerns and should bedirected by a corrosion expert. BSK does not practice corrosion engineering.

4.3 Site Preparation RecommendationsThe following procedures must be implemented during Site preparation for the proposed Siteimprovements. References to maximum dry density, optimum moisture content, and relative compactionare based on ASTM D1557 (latest test revision) laboratory test procedures.

1. The areas of proposed improvements must be cleared of surface vegetation and debris. Materialsresulting from the clearing and stripping operations must be removed and properly disposed ofoff-site. In addition, all undocumented fills should be removed where encountered and where fillsor structural improvements will be placed.


2. Where existing utilities, inlets, or underground tanks are present, they should be removed to apoint at least 2 feet horizontally outside the proposed foundation and pavement areas. Resultantcavities must be backfilled with engineered fill compacted in accordance with therecommendations presented in this report.

3. Following the stripping operations, the areas where shallow foundations are proposed must beoverexcavated to a minimum depth of 1-foot below existing site grades or 1-foot below thebottom of the footing elevation, whichever is deeper. After overexcavation, the bottom of theexposed soil should be scarified 12 inches, moisturized to optimum moisture content, andcompacted to 90 percent of ASTM D1557. Over excavation should extend laterally three feetbeyond the edge of foundations. Yielding areas should be observed by the geotechnicalconsultant and removed and recompacted if necessary.

4. Following the required stripping and overexcavation, in the areas of proposed shallowfoundations, the exposed ground surface at the bottom of the overexcavation must be inspectedby the Geotechnical Engineer to evaluate if loose or soft zones are present that will requireadditional overexcavation.

5. The upper 1-foot of the finished subgrade should be non-expansive soil. If soil is imported to thesite it must be free of organic materials or deleterious substances and meet the criteria for importfills below. The material must be free of oversized fragments greater than 3-inches in greatestdimension. Engineered fill underneath and extending 3 feet beyond the structure foundations andmust be placed in uniform layers not exceeding 8-inches in loose thickness, moisture conditionedat near optimum moisture content, and compacted to at least 90 percent relative compaction.

6. Exterior concrete flatwork should be underlain by 12 inches of non-expansive material.7. BSK must be called to the site to verify the import material properties through laboratory testing.8. If possible, earthwork operations should be scheduled during a dry, warm period of the year.

Should these operations be performed during or shortly following periods of inclement weather,unstable soil conditions may result in the soils exhibiting a “pumping” condition. This condition iscaused by excess moisture in combination with moving construction equipment, resulting insaturation and zero air voids in the soils. If this condition occurs, the adverse soils will need to beover-excavated to the depth at which stable soils are encountered and replaced with suitable soilscompacted as engineered fill. Alternatively, the Contractor may proceed with grading operationsafter utilizing a method to stabilize the soil subgrade, which should be subject to review andapproval by BSK prior to implementation.

9. Import fill materials must be free from organic materials or deleterious substances. The projectspecifications must require the contractor to contact BSK to review the proposed import fillmaterials for conformance with these recommendations at least one week prior to importing tothe Site, whether from on-site or off-site borrow areas. Imported fill soils must be non-hazardousand derived from a single, consistent soil type source conforming to the following criteria:

Plasticity Index: < 12Expansion Index: < 20 (Very Low Expansion Potential)Maximum Particle Size: 3 inchesPercent Passing #4 Sieve: 65 - 100Percent Passing #200 Sieve: 20 - 45


Low Corrosion Potential: Soluble Sulfates < 1,500 ppmSoluble Chlorides < 150 ppmMinimum Resistivity > 3,000 ohm-cm

4.4 FoundationsProvided the recommendations contained in this report are implemented during design and construction,it is our opinion that the structures can be supported on shallow or mat foundations and pole-typefoundations such as drilled piers. A structural engineer should evaluate reinforcement and embedmentdepth based on the requirements for the structural loadings, shrinkage and temperature stresses.

4.4.1 Shallow FoundationsContinuous and isolated spread footings must have a minimum width of 12 inches and 24 inches,respectively. The minimum foundation depth for spread footings is 12 inches. Continuous and isolatedspread footing foundations may be designed using a net allowable bearing pressure of 2,800 pounds persquare foot (psf). The net allowable bearing pressure applies to the dead load plus live load (DL + LL)condition; it may be increased by 1/3 for wind or seismic loads.

4.4.2 Mat FoundationsWe understand that the structure may be supported on a concrete mat foundation. The mat foundationmay be designed to impose a maximum allowable pressure of 2,000 pounds per square foot (psf) due todead plus live loads. This value may be increased by one-third for transient loads such as seismic or wind.The concrete mat foundation should be embedded at least 8 inches below the lowest adjacent grade.

4.4.3 Pole-Type FoundationsThe structure may be supported on pole-type foundations such as drilled piers. This type of foundationshould be designed in accordance with Section 1807.3 of the 2016 CBC. However, it is recommended thatan allowable lateral soil bearing pressure of 190 per foot of embedment be used to develop parametersS1 and S3 rather than one of the values given in Table 1806.2. This value includes a factor of safety of 2.The upper one foot of the soil should be ignored when calculating the minimum embedment depth. Thelateral bearing pressure shall be permitted to be increased by 1/3 where used with the alternative basicload combinations of CBC Section 1605A.3.2 that include wind or earthquake loads.

Drilled piers may be designed for an allowable average skin friction of 400 psf (includes a factor of safetyof 2) to support vertical loads applied to the pier foundations. Drilled piers should have a minimumembedment length of 4 feet and minimum diameter of 24 inches but should be sized according to designloads. Drilled piers should be spaced a minimum of 3 pile diameters apart. The total settlement of pilefoundations designed in accordance with these recommendations should not exceed one-half inch.

4.4.4 Pole-Type Foundation ConsiderationsCasing may be required when drilling in loose and/or dry sands. BSK recommends that the means andmethod be determined by an experienced drilling contractor in the area. If the casing is left in place, BSKrecommends under drilling the hole and driving casing to ensure cohesion between the casing and thesoil. For this condition, skin friction in both up and down directions may be considered in the design. The


allowable downward skin friction value of 300 psf and allowable uplift skin friction of 300 psf may beincreased by 1/3 where used with the alternative basic load combinations of CBC Section 1605A.3.2 thatinclude wind or earthquake loads. These values are applicable both above and below the historic groundwater table during seismic loading and all other applicable loads.

For drilled pier foundations, prior to placing reinforcing steel or concrete, loose or disturbed soils shouldbe removed from drilled pier excavations. If end bearing is used to provide vertical support for the plannedstructures, a clean out bucket should be used to remove loose soil from the bottom of the pier holes.Alternatively, the bottom of the holes should be tamped to the satisfaction of the Geotechnical Engineerto compact loose soil at the bottom of the pier holes. A representative of BSK should observe the drillingand clean-out associated with the construction of pier foundations to assess whether the actual bearingconditions are compatible with the conditions anticipating during the preparation of this report. Werecommend that construction of the drilled piers be completed on the same day the holes are drilled toreduce the potential for drying of the soil along the sides of the hole. In the event the construction ofdrilled piers is not completed on the same day, the holes shall be viewed by the Geotechnical Engineerprior to pouring concrete to determine if holes require any additional modifications (e.g. if the soil isallowed to dry out, the pier holes should be reamed to remove any cracked, desiccated soil). A concretemix with a low water/cement ratio should be used in the construction of the piers to reduce shrinkage ofthe concrete. To increase the fluidity of the mix for improved consolidation and bond with the reinforcingsteel, an increased slump may be desirable. This should be achieved by using a plasticizer as opposed toadding water to the mix.

If water is encountered within the drilled pier holes, whether from surface or subsurface sources, no morethan 6 inches of standing water should be present during concrete placement. Otherwise, the water needsto be pumped out or the concrete needs to be placed into the hole using tremie methods. If tremiemethods are used, the end of the tremie pipe must remain below the surface of the in-place concrete atall times. In order to develop the design skin friction value previously provided, concrete used for pierconstruction should have a slump of 6 to 8 inches.

4.5 Lateral Earth Pressures and Frictional ResistanceProvided the Site is prepared as recommended above, the following earth pressure parameters forfootings or mat foundations may be used for design purposes. The parameters shown in the table beloware for drained conditions of select engineered fill or undisturbed or recompacted native soil.

Table 2: Recommended Static Lateral Earth Pressures for Footings

Lateral Pressure Condition Equivalent Fluid Density (pcf) Drained Condition

Active Pressure 40

At Rest Pressure 60

Passive Pressure 380


The lateral earth pressures listed herein are obtained by the conventional equation for active, at rest, andpassive conditions assuming level backfill and a bulk unit weight of 120 pcf for the Site soils. A coefficientof friction of 0.28 may be used between soil subgrade and the bottom of footings. Unless the soil adjacentto the foundation is covered with concrete or asphalt paving, the upper one foot of soil should be ignoredfor passive resistance calculations.

The coefficient of friction and passive earth pressure values given above represent ultimate soil strengthvalues. BSK recommends that a safety factor consistent with the design conditions be included in theirusage in accordance with Sections 1806.3.1 through 1806.3.3 of the 2019 CBC. For stability against lateralsliding that is resisted solely by the passive earth pressure against footings or friction along the bottom offootings, a minimum safety factor of 1.5 is recommended. For stability against lateral sliding that isresisted by combined passive pressure and frictional resistance, a minimum safety factor of 2.0 isrecommended. For lateral stability against seismic loading conditions, a minimum safety factor of 1.2 isrecommended.

4.6 Slab-On-GradeInterior concrete floor slabs and exterior concrete flatwork, such as driveways, non-structural detachedpatios, sidewalks and trash enclosures may experience some cracking due to finishing, curing process,moisture content, mixed design and underlying soils. To reduce the possibility for cracking to occur on theconcrete slab the following recommendation should be implemented.

All interior slabs should be a minimum of 6-inches thick and exterior slabs should be a minimum of 5-inches thick and reinforced with a minimum of No. 4 rebar spaced 18 inches center to center, eachdirection. For concrete slabs subject to heavy traffic loads, such as trash enclosures should be a minimumof 6-inches thick and reinforced with a minimum of No. 4 rebar spaced 12-inches center to center, eachdirection. Special attention should be taken so that reinforcement is placed at the slab mid-height and atproper clearances. The provided slab thickness recommendations are only a minimum, actual slabthickness and reinforcement should be determined by the project Structural Engineer according to loadingconditions.

All slabs should be underlain by a minimum of 4-inches of Class 2 Aggregate base or clean crushed rock toenhance subgrade support for the slab. If this material is desired to be used as a capillary break, it shouldbe ¾ inch maximum size with no more than 10 percent by weight passing the #4 sieve.

The near-surface soils appear to have a low expansion potential but could be subject to some shrink/swellcycles with fluctuations in moisture content. Some of the adverse effects of swelling and shrinking can bereduced with proper moisture treatment. The intent is to reduce the fluctuations in moisture content bymoisture conditioning the soils, sealing the moisture in, and controlling it. Prior to placing concrete, theunderlying soil should be thoroughly wetted to moisture condition the soil and to seal any desiccationcracks.


Subsurface moisture and moisture vapor migration upward to the surface of the concrete and adverselyaffect floor coverings. A vapor retarder membrane should be installed between the prepared aggregatebase or crushed rock of the building pad and the interior slab to minimize moisture condensation underthe floor coverings and/or upward vapor transmission. The vapor barrier membrane should be aminimum 15-mil extruded polyolefin plastic that complies with ASTM E1745 Class A and have a permeanceof less than 0.01 perms per ASTM E96 or ASTM F1249. It is noted that polyethylene films (visqueen) donot meet these specifications. The vapor barrier must be adequately lapped and taped/sealed atpenetrations and seems in accordance with ASTM E1643 and the manufacturer’s specifications. The vaporretarder must be placed continuously across the slab area. Building design and construction have a greaterrole in perceived moisture problems since sealed buildings/rooms or inadequate ventilation may produceexcessive moisture in a building and affect indoor air quality.

It is emphasized that we are not floor moisture proofing experts. We make no guarantee nor provide anyassurance that use of capillary break/vapor retarder system will reduce concrete slab-on-grade floormoisture penetration to any specific rate or level, particularly those required by floor coveringmanufacturers. The builder and designers should consider all available measures for floor slab moistureprotection. Various factors such as surface grades, adjacent planters, the quality of slab concrete and thepermeability of the on-site soils affect slab moisture and can control future performance. In many cases,floor moisture problems are the result of either improper curing of floors slabs or improper application offlooring adhesives. We recommend contacting a flooring consultant experienced in the area of concreteslab-on-grade floors for specific recommendations regarding your proposed flooring applications.

Special precautions must be taken during the placement and curing of all concrete slabs. Excessive slump(high water-cement ratio) of the concrete and/or improper curing procedures used during either hot or coldweather conditions could lead to excessive shrinkage, cracking, or curling of the slabs. High water-cementratio and/or improper curing also greatly increase the water vapor permeability of concrete. We recommendthat all concrete placement and curing operations be performed in accordance with the American ConcreteInstitute (ACI) manual.

Interior and exterior slabs should have crack control saw cut control joints (i.e., weakened plane joints) toallow for expansion and contraction of the concrete. In general control joints should be spaced no morethan 20 times the slab thickness in each direction. The actual joint layout and design should be providedby the Architect and/or Structural Engineer. Expansion joint material should be used between flatworkand buildings.

Trees and other large plants can significantly contribute to differential settlement of a foundation,flatwork, and paved areas. The roots of trees and large plants can absorb the moisture from the soil,causing the soil to shrink or collapse much faster than other soil areas exposed to the weather. The soilwhere the moisture is lost more rapidly will sink lower than the surrounding soil, causing differentialsettlement in overlying or adjacent improvements. Certain trees and plants are known to be morehydrophilic (water-demanding) than others. Research studies indicate that a tree should be at least as faraway from a building, flatwork, and pavement as the mature height of the tree to minimize the effect of


drying caused by the tree. If this is not possible, consideration should be given to installing a root barrierbetween areas planted with trees and nearby foundations and flatwork. Exterior grading will have animpact on potential moisture beneath the floor slab. Recommendations for exterior draining are providedin the “Drainage Considerations” section of this report.

4.7 PavementsWe have made our flexible pavement designs assuming the pavement subgrade soil will be similar to thenear surface soils described in the boring logs. We ran an R-Value test on a bulk sample collected fromthe upper 3 feet in boring B-4, which resulted in a value of 43.

Pavement designs for various Traffic Indices (TIs) based on an R-Value of 43 are presented below. Each TIrepresents a different level of use. The appropriate traffic index (TI) should be determined by the projectCivil Engineer in conformance with the City and/or County specifications.

Table 3: Pavement Design RecommendationsR-Value = 43

Traffic Index AC1

(inches)AB2

(inches)

4.0 2.5 4.0

4.5 2.5 4.0

5.0 2.5 4.0

5.5 3.0 4.5

6.0 3.0 5.0

6.5 3.5 6.0

7.0 4.0 6.5

1. Asphalt Concrete2. Caltrans Class 2 Aggregate Base (Minimum R-Value = 78)

For preparation of the subgrade in areas to receive pavement and after required excess material has beenremoved, we recommend the upper 12 inches of the subgrade soil be scarified, moisture conditioned andcompacted to a minimum relative compaction of 95% at a moisture content at or above optimum inaccordance with the grading recommendations specified in this report. Should deflection/pumpingconditions be encountered, supplemental recommendations will be provided. The aggregate basematerial shall be ¾ inch Caltrans Class 2 aggregate base and conform with the latest addition of CaltransStandards. Aggregate base should be compacted to a minimum relative compaction of 95% at a moisturecontent at or above optimum in accordance with the grading recommendations specified in this report.Asphalt concrete shall conform with the latest addition of Caltrans Standard Specifications.

Pavements will experience deteriorating quality, performance and decreased longevity where water isallowed to migrate into the aggregate base and subgrade soils layers. Therefore, paved areas should be


sloped, and drainage gradients maintained to carry all surface water to appropriate collection points.Surface water ponding should not be allowed anywhere on the site during or after construction. Werecommend that the pavement section be isolated from non-developed areas and areas of intrusion ofirrigation water from landscaped areas. Concrete curbs should extend a minimum of 2 inches below theaggregate base and into the subgrade to provide a barrier against drying of the subgrade soils, orreduction of migration of landscape water, into the pavement section.

4.9 Excavation StabilitySoils encountered within the depth explored are generally classified as Type C soils in accordance withOSHA (Occupational Safety and Health Administration). The slopes surrounding or along temporaryexcavations may be vertical for excavations that are less than five feet deep and exhibit no indication ofpotential caving, but should be no steeper than 1.5H:1V for excavations that are deeper than five feet, upto a maximum depth of 15 feet. Certified trench shields or boxes may also be used to protect workersduring construction in excavations that have vertical sidewalls and are greater than 5 feet deep.Temporary excavations for the project construction should be left open for as short a time as possible andshould be protected from water runoff. In addition, equipment and/or soil stockpiles must be maintainedat least 10 feet away from the top of the excavations. Because of variability in soils, BSK must be affordedthe opportunity to observe and document sloping and shoring conditions at the time of construction.Slope height, slope inclination, and excavation depths (including utility trench excavations) must in nocase exceed those specified in local, state, or federal safety regulations, (e.g., OSHA Health and SafetyStandards for Excavations, 29 CFR Part 1926, or successor regulations).

4.10 Trench Backfill and CompactionProcessed on-site soils, which are free of organic material, are suitable for use as general trench backfillabove the pipe envelope. Native soil with particles less than three inches in the greatest dimension maybe incorporated into the backfill and compacted as specified above, provided they are properly mixed intoa matrix of friable soils. The backfill must be placed in thin layers not exceeding 12 inches in loosethickness, be well-blended and consistent texture, moisture conditioned to at least optimum moisturecontent, and compacted to at least 90 percent of the maximum dry density as determined by the ASTMD1557. The uppermost 12 inches of trench backfill below pavement sections must be compacted to atleast 95 percent of the maximum dry density as determined by ASTM D1557. Moisture content at or aboveoptimum must be maintained while compacting this upper 12-inch trench backfill zone.

We recommend that trench backfill be tested for compliance with the recommended relative compactionand moisture conditions. Field density testing should conform to ASTM Test Methods D1556 or D6938.We recommend that field density tests be performed in the utility trench bedding, envelope and backfillfor every vertical lift, at an approximate longitudinal spacing of not greater than 150 feet. Backfill thatdoes not conform to the criteria specified in this section should be removed or reworked, as applicableover the trench length represented by the failing test so as to conform to BSK recommendations.

4.11 Drainage ConsiderationsThe control surface drainage in the project areas is an important design consideration. BSK recommendsthat final grading around shallow foundations must provide for positive and enduring drainage away from


the structures, and ponding of water must not be allowed around, or near the shallow foundations.Ground surface profiles next to the shallow foundations must have at least a 2 percent gradient awayfrom the structures per the requirements in the 2019 CBC.

5. PLANS AND SPECIFICATIONS REVIEW

BSK recommends that it be retained to review the draft plans and specifications for the project, withregard to foundations and earthwork, prior to their being finalized and issued for construction bidding.

6. CONSTRUCTION TESTING AND OBSERVATIONS

Geotechnical testing and observation during construction is a vital extension of this geotechnicalinvestigation. BSK recommends that it be retained for those services. Field review during site preparationand grading allows for evaluation of the exposed soil conditions and confirmation or revision of theassumptions and extrapolations made in formulating the design parameters and recommendations. BSK’sobservations must be supplemented with periodic compaction tests to establish substantial conformancewith these recommendations. BSK must also be called to the Site to observe foundation excavations, priorto placement of reinforcing steel or concrete, in order to assess whether the actual bearing conditions arecompatible with the conditions anticipated during the preparation of this report. BSK must also be calledto the Site to observe placement of foundation and slab concrete.

If a firm other than BSK is retained for these services during construction, then that firm must notify theowner, project designers, governmental building officials, and BSK that the firm has assumed theresponsibility for all phases (i.e., both design and construction) of the project within the purview of theGeotechnical Engineer. Notification must indicate that the firm has reviewed this report and anysubsequent addenda, and that it either agrees with BSK’s conclusions and recommendations, or that itwill provide independent recommendations.

7. LIMITATIONS

The analyses and recommendations submitted in this report are based upon the data obtained from theborings performed at the approximate locations shown on the Boring Location Map, Figure A-2. The reportdoes not reflect variations which may occur between or beyond the borings. The nature and extent ofsuch variations may not become evident until construction is initiated. If variations then appear, a re-evaluation of the recommendations of this report will be necessary after performing on-site observationsduring the excavation period and noting the characteristics of the variations.

The validity of the recommendations contained in this report is also dependent upon an adequate testingand observation program during the construction phase. BSK assumes no responsibility for constructioncompliance with the design concepts or recommendations unless it has been retained to perform thetesting and observation services during construction as described above.

The findings of this report are valid as of the present. However, changes in the conditions of the Site canoccur with the passage of time, whether caused by natural processes or the work of man, on this property


or adjacent property. In addition, changes in applicable or appropriate standards may occur, whether theyresult from legislation, governmental policy or the broadening of knowledge.

BSK has prepared this report for the exclusive use of the Client and members of the project design team.The report has been prepared in accordance with generally accepted geotechnical engineering practiceswhich existed in San Joaquin County at the time the report was written. No other warranties eitherexpressed or implied are made as to the professional advice provided under the terms of BSK’s agreementwith Client and included in this report.

8. REFERENCES

Department of Water Resources. http://www.water.ca.gov/waterdatalibrary/ , Water Data Library, 2020

Earth Point. http://earthpoint.us/townships.aspx, Public Land Survey System, Google Earth, 2020.

Lee, Norman. California Geomorphic Provinces (2012): n. pag. California Department of Conservation.California Geological Survey.<http://www.conservation.ca.gov/cgs/information/publications/cgs_notes/note_36/Documents/note_36.pdf >.

USGS/OSHPD, U.S. Seismic Design Maps, https://seismicmaps.org/.

APPENDIX A

FIELD EXPLORATION

APPENDIX A

FIELD EXPLORATION

The field exploration for this investigation was conducted under the oversight of a BSK Engineer. Five (5)test borings were drilled at the site on September 1, 2020 by Baja Exploration using a CME 75 Drill Rig.The test borings were drilled to a maximum depth of approximately 36½ feet below existing groundsurface (bgs). A geotechnical boring permit was obtained from San Joaquin County Department ofEnvironmental Health.

The soil materials encountered in the test borings were visually classified in the field, and the logs wererecorded during the drilling and sampling operations. Visual classification of the materials encountered inthe test borings was made in general accordance with the Unified Soil Classification System (ASTM D2488).A soil classification chart is presented herein. Boring logs are presented herein and should be consultedfor more details concerning subsurface conditions. Stratification lines were approximated by the field staffbased on observations made at the time of drilling, while the actual boundaries between soil types maybe gradual and soil conditions may vary at other locations.

Subsurface samples were obtained at the successive depths shown on the boring logs by driving samplerswhich consisted of a 2.5-inch inside diameter (I.D.) California Sampler and a 1.4-inch I.D. StandardPenetration Test (SPT) Sampler. The samplers were driven 18 inches using a 140-pound hammer droppedfrom a height of 30 inches by means of either an automatic hammer or a down-hole safety hammer. Thenumber of blows required to drive the last 12 inches was recorded as the blow count (blows/foot) on theboring logs. The relatively undisturbed soil core samples were capped at both ends to preserve thesamples at their natural moisture content. Soil samples were also obtained using the SPT Sampler linedwith metal tubes or unlined in which case the samples were placed and sealed in polyethylene bags. Atthe completion of the field exploration, the test borings were backfilled with the excavated soil cuttingsand the CPTs were backfilled with bentonite.

It should be noted that the use of terms such as “loose”, “medium dense”, “dense” or “very dense” todescribe the consistency of a soil is based on sampler blow count and is not necessarily reflective of thein-place density or unit weight of the soils being sampled. The relationship between sampler blow countand consistency is provided in the following Tables A-1 and A-2 for coarse-grained (sandy and gravelly)soils and fine grained (silty and clayey) soils, respectively.

Table A-1: Apparent Relative Density of Coarse-Grained Soil by Sampler Blow Count

Consistency Descriptor SPT Blow Count(#Blows / Foot)

2.5” I.D. California Sampler BlowCount (#Blows / Foot)

Very Loose <4 <6Loose 4 – 10 6 – 15

Medium Dense 10 – 30 15 – 45Dense 30 – 50 45 – 80

Very Dense >50 >80

Table A-2: Consistency of Fine-Grained Soil by Sampler Blow Count

Consistency Descriptor SPT Blow Count(#Blows / Foot)

2.5” I.D. California Sampler BlowCount (#Blows / Foot)

Very Soft <2 <3Soft 2 – 4 3 – 6Stiff 4 – 8 6 – 12

Very Stiff 8 – 15 12 – 24Hard 15 – 30 24 – 45

REFERENCE IMAGE: USGS Topo

3140 Gold Camp Drive #160Rancho Cordova, CA 95670

Tel. (916) 853-9293

SITE VICINITY MAPStockton Soccer Complex Upgrades

10055 CA-99Stockton, California

FIGURE A-1JOB NO. G20-189-11S_____ DATE _September 2020__

DR. BY CG___ CH. BY __OML__SCALE AS SHOWN

SHEET NO. _1__OF _2__ SHEETS

0 0.35 mi 0.7 miScale: 1” = 0.7 mi

(APPROXIMATE)

SITE

REFERENCE IMAGE: Siegfried Engineering Inc.

3140 Gold Camp Drive #160Rancho Cordova, CA 95670

Tel. 916.853.9293

BORING LOCATION MAPStockton Soccer Complex Upgrades

10055 CA-99Stockton, California

FIGURE A-2JOB NO. G20-189-11S____DATE _September 2020_

DR. BY CG___ CH. BY __OML__SCALE AS SHOWN

SHEET NO. _2__OF _2__ SHEETS

0 90’ 180’Scale: 1” = 180’(APPROXIMATE)

LEGEND:

APPROXIMATE BORING LOCATIONSB-1

B-5

B-1

B-4

B-3B-2

MAJOR DIVISIONS TYPICAL NAMESCO

ARSE

GRAI

NED

SOIL

SM

ore

than

Hal

f>#2

00GRAVELS

MORE THAN HALFCOARSE FRACTION

IS LARGER THANNO. 4 SIEVE

CLEAN GRAVELSWITH LITTLE ORNO FINES

GW WELL GRADED GRAVELS, GRAVEL-SAND MIXTURES

GP POORLY GRADED GRAVELS, GRAVEL- SAND MIXTURES

GRAVELS WITHOVER 15% FINES

GM SILTY GRAVELS, POORLY GRADED GRAVEL-SAND-SILT MIXTURES

GC CLAYEY GRAVELS, POORLY GRADED GRAVEL-SAND-CLAY MIXTURES

SANDS

MORE THAN HALFCOARSE FRACTIONIS SMALLER THAN

NO. 4 SIEVE

CLEAN SANDSWITH LITTLEOR NO FINES

SW WELL GRADED SANDS, GRAVELLY SANDS

SP POORLY GRADED SANDS, GRAVELLY SANDS

SANDS WITHOVER 15% FINES

SM SILTY SANDS, POORLY GRADED SAND-SILT MIXTURES

SC CLAYEY SANDS, POORLY GRADED SAND-CLAY MIXTURES

FINE

GRAI

NED

SOIL

SM

ore

than

Hal

f<#2

00si

eve SILTS AND CLAYS

LIQUID LIMIT LESS THAN 50

ML INORGANIC SILTS AND VERY FINE SANDS, ROCK FLOUR, SILTY ORCLAYEY FINE SANDS, OR CLAYEY SILTS WITH SLIGHT PLASTICITY

CLINORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, GRAVELLY CLAYS,SANDY CLAYS, SILTY CLAYS,LEAN CLAYS

OL ORGANIC CLAYS AND ORGANIC SILTY CLAYS OF LOW PLASTICITY

SILTS AND CLAYS

LIQUID LIMIT GREATER THAN 50

MH INORGANIC SILTS , MICACEOUS OR DIATOMACIOUS FINE SANDY ORSILTY SOILS, ELASTIC SILTS

CH INORGANIC CLAYS OF HIGH PLASTICITY, FAT CLAYS

OH ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY, ORGANIC SILTS

HIGHLY ORGANIC SOILS Pt PEAT AND OTHER HIGHLY ORGANIC SOILS

Note: Dual symbols are used to indicate borderline soil classifications.

Pushed Shelby Tube Water Level measured at time of Drilling(with date noted)

Standard Penetration Test(2-inch outside diameter)

Water Level measured after Drilling(with date noted)

Modified California(3-inch outside diameter) Hand Auger Cuttings

Split Barrel Sampler(2 ½-inch outside diameter) Grab Sample

Undisturbed Sample Sample Attempt with No Recovery

Continuous Core Sample

SOIL CLASSIFICATION CHART AND LOG KEYUnified Soil Classification System (ASTM D 2487)

Figure A1

Surface: Sod

Sandy Lean CLAY (CL): brown, moist, very hard, fine grainedsand, trace organics, white and dark brown mottling, redstaining

Figure B-2: Expansion Index Test

less sand, harder

Figure B-1: Direct Shear Test

Lean CLAY (CL-CH): brown, moist, trace fine grained sand

less silt

thin layer of Clayey SAND: pale brown, moist, fine to coarsegrained, white striationsSilty SAND (SM): brown, moist, medium dense, fine grained,red staining, white striations, white and dark brown mottling

Sandy Lean CLAY (CL): brown, moist, hard, fine grained sand

992756

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BSK Associates3140 Gold Camp Dr. #160Rancho Cordova, CA 95670Telephone: 916.853.9293Fax: 916.853.9297

MATERIAL DESCRIPTION

Stockton Soccer Complex UpgradesG2018911S10055 CA-99, Stockton, CAC. GoodwinO. Lau

Project Name:Project Number:Project Location:Logged by:Checked by:

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Surface El.: 19.0

Drilling Equipment:Drilling Method:Drive Weight:Hole Diameter:Drop:Remarks:

LOG OF BORING NO. B-1

36.59/1/209/1/202.4 inch inner diameter1.4 inch inner diameter

CME 75 Drill Rig w/ auto hammerHollow Stem Auger140 lbs6 inches30 inchesBoring backfilled with grout and soil cuttings

Completion Depth:Date Started:Date Completed:California Sampler:SPT Sampler:

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Sandy Lean CLAY (CL): brown, moist, hard, fine grained sand(continued)

Clayey SAND (SC): dark yellowish brown, moist, mediumdense, fine to medium grained

Sandy Lean CLAY (CL): yellowish brown, moist, very hard,fine to medium grained sand, friable

not friable, decreased sand content

Silty SAND (SM): brown, moist, fine grained

Sandy Lean CLAY (CL): brown, moist, hard, fine grained sand

yellowish brown, increased sand content

Boring terminated at 36.5 feet.No groundwater observed.Backfilled with neat cement and soil cuttings.

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Surface: Sod

Sandy Lean CLAY (CL-CH): dark yellowish brown, slightlymoist, fine grained sand, dark brown mottling, low sand content

very hard

Figure B-4: Plasticity Index Test

yellowish brown, moist, decreased sand content, whitestriations, cemented chunks, friable layers

dark yellowish brown, hard

slightly moist

fine to coarse grained sand, increased sand content

46115

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Surface El.: 23.0






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Sandy Lean CLAY (CL-CH): dark yellowish brown, slightlymoist, fine grained sand, dark brown mottling, low sand content(continued)decreased sand contentincreased fine grained sand content

Clayey SAND (SC): dark yellowish brown, moist, mediumdense, fine to coarse grained, high fines content, white and darkbrown mottling

yellowish brown, moist, dense, fine to medium grained

dark yellowish brown, moist, dense, fine to coarse grained,increased sand content

Silty SAND (SM): yellowish brown, moist, medium dense, fineto coarse grained, low fines content

pale brown, fine to medium grained

light yellowish brown, fine grained, higher fines content


29

26

38

28

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ASPHALT CONCRETE (AC): AC = 3.5 inchesAGGREGATE BASE (AB): AB = 4 inchesSandy Lean CLAY (CL): brown, moist, hard, fine to mediumgrained, white striations

Clayey SAND (SC): dark yellowish brown, slightly moist,medium dense, fine to coarse grained

Poorly Graded SAND (SP): yellowish brown, dry, mediumdense, fine to medium grained

Silty CLAY (CL): brown, moist, hard, trace fine grained sand,red staining

Clayey SAND (SC): dark yellowish brown, moist, mediumdense, fine to coarse grained, red staining, white and darkbrown mottling

114

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Clayey SAND (SC): dark yellowish brown, moist, mediumdense, fine to coarse grained, red staining, white and darkbrown mottling (continued)

Sandy Lean CLAY (CL): grayish brown, moist, very hard, fineto medium grained

Silty CLAY (CL-ML): brown, slightly moist, stiff, trace finegrained sand

Clayey Silty SAND (SM): yellowish brown, moist, fine grained

Clayey SAND (SC): yellowish brown, moist, medium dense,fine to medium grained

Sandy Lean CLAY (CL): dark yellowish brown, moist, stiff,fine to medium grained


14

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Gravel paved surface

Sandy Lean CLAY (CL): dark yellowish brown, moist, fine tomedium grained sand

Figure B-3: R-Value Test

Boring terminated at 3 feet.No groundwater observed.Backfilled with soil cuttings.

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Location:

Surface El.: 36.0



3.09/1/209/1/20

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4 inches

Backfilled with soil cuttings


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Surface: Sod

Silty Clayey SAND (SC): dark yellowish brown, moist, fine tocoarse grained

Boring terminated at 3 feet.No groundwater observed.Backfilled with soil cuttings.

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Surface El.: 39.0



3.09/1/209/1/20

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APPENDIX B

LABORATORY TESTING RESULTS

APPENDIX B

LABORATORY TESTING

Moisture-Density TestsThe field moisture content, as a percentage of dry weight of the soils, was determined by weighing thesamples before and after oven drying in accordance with ASTM D2216 test procedures. Dry densities, inpounds per cubic foot, were also determined for undisturbed core samples in general accordance withASTM D2937 test procedures. Test results are presented on the boring logs in Appendix A.

Direct Shear TestOne (1) consolidated drained Direct Shear test was performed on a relatively undisturbed soil sampleobtained at the time of drilling in the area of planned construction. The test was conducted to determinethe soil strength characteristics. The standard test method is ASTM D3080, Direct Shear Test for Soil underConsolidated Drained Conditions. The direct shear test results are presented graphically on Figure B-1.

Expansion Index TestOne (1) Expansion Index Test was performed on a bulk soil sample obtained at the time of drilling in thearea of planned construction to determine the expansion characteristics of the sample. The test wasperformed in general accordance with ASTM Test Method D4829. The test results are presented on FigureB-2.

R-Value TestOne (1) Resistance-Value test was performed on a composite bulk soil sample obtained at the time ofdrilling in the area of planned construction to evaluate the subgrade material for pavement design. Thesoil was evaluated in accordance with ASTM Test Method D2844. The test results are presented in FigureB-3.

Plasticity Index TestOne (1) Plasticity Index Test was performed on a bulk soil sample obtained at the time of drilling in thearea of planned construction. The soil sample was tested for the liquid limits and plastic limits todetermine the plasticity index of each sample using ASTM Test Method D4318. The test results arepresented on Figure B-4, Table B-2, and the boring logs in Appendix A.

Table B-2: Summary of Plasticity Index Test Results

Sample Location Liquid Limit (%) Plastic Limit (%) Plasticity Index (%)

B-2 @ 1-5 feet bgs 46 18 28

Soil CorrosivityOne (1) corrosivity evaluation was performed on a bulk soil sample obtained at the time of drilling in thearea of planned construction. The corrosivity testing was performed by CERCO Analytical of Concord,California for minimum resistivity (ASTM G57), sulfate ion concentration (CT 417), chloride ionconcentration (CT 422), and pH of soil (ASTM D4972). The test results are presented in Table B-1 below.

Table B-1: Summary of Corrosion Test Results

Sample LocationMinimum Resistivity

(ohm-cm)pH

Sulfate,mg/kg

Chloride,mg/kg

B-3 @ 1-5 feet bgs 2,140 8.5 10 Not Detected

FIGURE B-1550 W. Locust

Fresno, CA 93650Ph: (559) 497-2880

Fax: (559) 497-2886

Project Name: Sample Date: 9/1/2020

Test Date: 9/8/2020

Project Number: Lab Tracking ID: Report Date: 9/9/2020

Sample Location: B-3 @ 6' Clayey SAND (SC): dark yellowish brown, moist, fine to coarse grained

Stockton Soccer Complex

Sample Description:

Direct Shear TestASTM D-3080

Sampled By:Tested By:

G20 - 189 - 11S N/A

D.Messfin

C. Goodwin

0

1

2

3

4

5

6

7

0 1 2 3 4 5 6 7 8

SHEA

R S

TRES

S (K

SF)

NORMAL STRESS (KSF)

SHEAR STRENGTH DIAGRAM

DRY DENSITY: 116.7 pcf

MOISTURE CONTENT: 9.8 %

INTERNAL FRICTION ANGLE, f = 31o

COHESION, c = 0.0 ksf

31 o

550 W. Locust AvenueFresno, CA 93650

Ph: (559) 497-2868Fax: (559) 485-6140

Project Name: Stockton Soccer Complex Report Date: 9/9/2020

Project Number: G20 - 189 - 11S Sample Date: 9/1/2020

Lab Tracking ID: Test Date: 9/8/2020

Sample Location: B - 3 @ 1' - 5'

Sample SourceSampled By: Tested By: Reviewed By:

0.2976 EI0.34995 0 - 200.05235 21 - 50

51 - 9052 91 - 130

51 >130Corrected Expansion Index, EI Very High

Moisture Content (%)

Potential Expansion

123.1

Uncorrected Expansion Index

Expansion (in)

Remolded Wet Density (pcf) 116.9

Remolded Dry Density (pcf) 105.8 Final Dry Density (pcf)

Final Wet Density (pcf)

Final Gauge Reading (in)

48100.5

Initial Gauge Reading (in)

High

Classification of Expansive Soil

90Degree of Saturation Degree of Saturation

Very Low

Low

Medium

Initial Volume (ft3)

Moisture Content Data100.0

Final Volume (ft3) 0.007653

22.5%

Dry Weight + Tare 269.5

Tare Weight (g)10.5%

Wet Weight + Tare

16.3

90.5

0

Wet Weight + Tare 326.5

368.6

Expansion Index of SoilsASTM D 4829 / UBC Standard 18-2

INITIAL SET-UP DATA

FINAL TAKE-DOWN DATA

TEST DATA

D.Messfin O. LauC. Goodwin

FIGURE B-2

Sample + Tare Weight (g)

Tare Weight (g)

754.1

EXPANSION READINGS

Dry Weight + Tare

Tare Weight (g)Moisture Content (%)

0.007272

Moisture Content Data

FIGURE B-3700 22nd St.

Bakersfield, CA 93301Ph: (661) 327-0670

Fax: (661) 324-4217

Sample Date: 9/1/2020Test Date: 9/15/2020

Report Date: 9/17/2020Tested By: ILT Remotigue

SPECIMEN A B CEXUDATION PRESSURE, LOAD (lb) 8123.6 5638.6 2631.2EXUDATION PRESSURE, PSI 647 449 209EXPANSION, * 0.0001 IN 0.0027 0.0021 0.0030EXPANSION PRESSURE, PSF 0 0 0STABILOMETER PH AT 2000 LBS 46 67 78DISPLACEMENT 4.02 3.92 3.56

61 47 4261 47 424.5 5.5 6.5

DRY DENSITY AT TEST, PCF 124.8 123.6 121.1

"R" VALUE BY EXPANSION

Sample Description:

Stockton Soccer ComplexG20-189-11S

Lab Tracking ID:Sample Location:

CL: Sandy Lean CLAY: dark yellowish brown, moist, fine to medium grained sand

Standard Test Methods for Resistance R-Value andExpansion Pressure of Compacted Soil

B20-139B-4 @ 1-3 feet bgs

Project Name:Project Number:

ASTM D-2844

43

N/APRESSURE TI = 4.0, GF=1.50

RESISTANCE VALUE "R"

% MOISTURE AT TEST

"R" VALUE AT 300 PSIEXUDATION PRESSURE

"R" VALUE CORRECTED FOR HEIGHT

COVER THICKNESS BY EXPANSION PRESSURE, INCHES

"R" V

ALU

E

CO

VER

TH

ICKN

ESS

BY S

TABI

LOM

ETER

, IN

CH

ES

EXUDATION PRESSURE, PSI

0 2 4 6 8 10 12 14 16 18 20 22 24 26

100

90

80

70

60

50

40

30

20

10

0

0

2

4

6

8

10

12

14

16

18

20

22

2410020300400500600700800 0

Reviewed By: Ian Leo T. Remotigue

550 W. Locust Ave.Fresno, CA 93650

Ph: (559) 497-2868Fax: (559) 497-2886

Project Name: Report Date: 9/9/2020Project Number: Sample Date: 9/1/2020Sampled By: Tested By: Test Date: 9/9/2020

Sample #Sample IDLocation

Description

Wet+Tare (g) 24.92 24.40 24.51

Dry+Tare (g) 19.92 19.37 19.20

Tare (g) 8.49 8.47 8.46

Spec. Blows 25-35 20-30 15-25

No. of Blows 32 24.00 17

LL 43.7 46.1 49.4

Corrected LL

Wet+Tare (g) 28.28 27.99

Dry+Tare (g) 27.02 26.76

Tare (g) 20.19 20.18

M.C. 18.4 18.7

Results Results ResultsAVG L.L. 46.2

AVG P.L. 18.6

P.I. 28

USCS Symbol

Remarks:

FIGURE B-4

1 2 3

Stockton Soccer ComplexG20 - 189 - 11SC. Goodwin B - 2 @ 1' - 5'

Liquid Limit Data

LIQUID LIMIT (LL), PLASTIC LIMIT (PL), ANDPLASTICITY INDEX (PI) OF SOILS

ASTM D-4318

B - 2 @ 1' - 5'

Specification

Plastic Limit Data

SpecificationSpecification

1

0.0

10.0

20.0

30.0

40.0

50.0

60.0

0 10 20 30 40 50 60 70 80 90 100

PLAS

TIC

ITY

IND

EX [%

]

LIQUID LIMIT [%]

PLASTICITY CHART

CL

CH or OH

CL - MLML or OL

MH or OH