geotechnical engineering report - denton, texas...d&s engineering labs, llc vela athletic...

Geotechnical Engineering Report

Vela Athletic Complex Denton, TX

February 5, 2016

D&S ENGINEERING LABS, LLC Vela Athletic Complex – Denton, Texas (16-0009)

TABLE OF CONTENTS

1.0 PROJECT DESCRIPTION ...................................................................................... 1

2.0 PURPOSE AND SCOPE ........................................................................................ 1

3.0 FIELD AND LABORATORY INVESTIGATION ....................................................... 2

3.1 General ............................................................................................................. 2

3.2 Laboratory Testing ............................................................................................ 3

3.2.1 Overburden Swell Tests ........................................................................... 3

4.0 SITE CONDITIONS ................................................................................................ 4

Stratigraphy ...................................................................................................... 4

Groundwater ..................................................................................................... 4

5.0 ENGINEERING ANALYSIS .................................................................................... 4

Estimated Potential Vertical Movement (PVM) ................................................. 4

6.0 FOUNDATION RECOMMENDATIONS .................................................................. 5

6.1 Shallow Footing Foundations............................................................................ 6

6.1.1 Soil-Supported Floor System ................................................................... 6

6.1.2 Perimeter Moisture Barrier ....................................................................... 7

Slab-on-Grade Foundation ............................................................................... 7

6.2.1 Post-Tensioning Institute (PTI) Design Parameters ................................. 7

6.2.2 PTI Design Assumptions: ......................................................................... 7

Straight-sided Drilled Shafts ............................................................................. 8

Lateral Loads .................................................................................................... 8

Drilled Shaft Construction Considerations ........................................................ 9

7.0 EARTHWORK RECOMMENDATIONS ................................................................ 10

Earthwork Preparation for the Building Pads .................................................. 10

Earthwork Preparation for the Soccer Fields .................................................. 11

Additional Considerations ............................................................................... 11

8.0 PAVEMENT RECOMMENDATIONS .................................................................... 12

General ........................................................................................................... 12

Behavior of Soils beneath Pavement .............................................................. 12

Pavement Subgrade Preparation.................................................................... 13

8.3.1 Lime Treatment Recommendations ....................................................... 14

8.3.2 Soil Preparation – Flexible Base ............................................................ 16

Rigid Pavement .............................................................................................. 16

8.4.1 Pavement Joints and Cutting ................................................................. 16


9.0 CULVERTS ........................................................................................................... 17

Lateral Pressures ............................................................................................ 17

Design and Construction Considerations ........................................................ 18

Scour Potential ............................................................................................... 18

10.0 SEISMIC CONSIDERATION ................................................................................ 18

11.0 LIMITATIONS ....................................................................................................... 19

APPENDIX A – BORING LOGS AND SUPPORTING DATA APPENDIX B – GENERAL DESCRIPTION OF PROCEDURES

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GEOTECHNICAL INVESTIGATION VELA ATHLETIC COMPLEX

DENTON, TEXAS

1.0 PROJECT DESCRIPTION

This report presents the results of the geotechnical investigation for the proposed new Vela Athletic Complex, which will be located at the southwest side of the intersection of Riney Road and US Highway 77, Denton, Texas. The new facility will consist of four soccer fields and associated parking and driveway access. Culverts will be provided along the driveway access to North Elm Street. Bleachers, light poles, stadium lighting, and a small plaza area are planned. The plaza area will include a restroom building and a group pavilion structure. Two pedestrian trail bridges are planned just southwest and southeast of the soccer field area.

The proposed location of the new facility is currently undeveloped and covered with grass and a few trees and bushes. Based on site observations, the ground surface at this site is relatively flat terrain. For this geotechnical investigation, a total of 11 borings were advanced 10 to 35 feet deep beneath the proposed facility footprint. Photographs showing the current condition of the site are provided below.

2.0 PURPOSE AND SCOPE

The purpose of this investigation was to:

Identify the subsurface stratigraphy present at the site.

Evaluate the physical and engineering properties of the subsurface soil and bedrock strata for use in the geotechnical analyses.

Provide geotechnical recommendations for use in the design of foundations and earthwork preparation for the new facility.


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The scope of this investigation consisted of:

Drilling and sampling eleven (11) soil borings across the site to depths of about 10 to 35 feet below existing grade.

Laboratory testing of soil samples obtained during the field investigation.

Preparation of a Geotechnical Report that includes:

o Evaluation of potential soil heave through Potential Vertical Movement (PVM) estimates.

o Recommendations for the design of foundations:

Shallow footings Slab-on-grade Drilled shafts

o Recommendations for earthwork.

o Recommended subgrade modification to reduce the PVM.

o Pavement recommendations.

o Culvert recommendations.

3.0 FIELD AND LABORATORY INVESTIGATION

3.1 General

A field and laboratory testing program was completed as part of this investigation. The borings were advanced utilizing truck-mounted drilling equipment outfitted with continuous flight augers. Undisturbed samples of the soils were obtained using 3-inch diameter tube samplers, which were advanced into the soils in 1-foot increments by the continuous thrust of a hydraulic ram located on the drilling equipment. After sample extrusion, a field determination of the unconfined compressive strength of each cohesive soil and bedrock sample was obtained using a calibrated hand penetrometer.

Texas Highway Department Cone Penetration Tests were performed to examine the resistance of the bedrock materials to penetration. In this test a 3-inch diameter steel cone is driven by energy equivalent of a 170-pound hammer freely falling 24 inches and striking an anvil at the top of the drill string. Depending on the resistance of the materials, either the number of the blows of the hammer required to provide 12 inches of penetration, or the inches of penetration of the cone due to 100 blows of the hammer are recorded in increments of either 6-inch penetration, or 50 blows.

All samples obtained were extruded in the field, placed in plastic bags to minimize changes in the natural moisture condition, labeled according to the appropriate boring number and depth, and placed in protective cardboard boxes for transportation to the laboratory. The approximate locations of the borings performed at the site are shown


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on the boring location map that is included in Appendix A. The specific depths, thicknesses and descriptions of the strata encountered are presented on the individual Boring Log illustrations, which are also included in Appendix A. Strata boundaries shown on the boring logs are approximate.

3.2 Laboratory Testing

Laboratory testing was performed on selected samples of the soils. In order to identify the relevant engineering characteristics of the subsurface materials encountered and to provide data for developing engineering design parameters. The subsurface materials recovered during the field exploration were described by an engineering geologist in the testing laboratory and were later refined by a Geotechnical Engineer based on results of the laboratory tests performed.

All recovered soil samples were classified and described in part using the Unified Soil Classification System (USCS) and other accepted procedures. In order to determine soil characteristics and to aid in classifying the soils, index property and classification testing was performed on selected soil samples as requested by the Geotechnical Engineer. Index property and classification tests were each performed in general accordance with the following ASTM testing standards:

Moisture Content ASTM D 2216

Atterberg Limits ASTM D 4318

Percentage of Particles Finer Than the No. 200 Sieve ASTM D 1140

Additional tests were performed to aid in evaluating soil strength and volume change characteristics, which consisted of the following:

Overburden Swell Testing

The results of these tests are presented at the corresponding sample depths in the appropriate Boring Log illustrations. The index property and classification testing procedures are described in more detail in Appendix B (General Description of Procedures).

3.2.1 Overburden Swell Tests

Selected samples of the near-surface soils and the weathered bedrock were subjected to overburden swell testing. For this test, a sample is placed in a consolidometer and is subjected to the estimated overburden pressure. The sample is then inundated with water and is allowed to swell. Moisture contents are determined both before and after completion of the test. Test results are then recorded, including the percent swell and the initial and final moisture contents.


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4.0 SITE CONDITIONS

Stratigraphy

Based upon a review of the recovered samples, as well as the Geologic Atlas of Texas, Sherman Sheet, this site is in an area characterized by soil and bedrock strata associated with the Grayson Marl and Main Street Formation, undivided.

Surficial high plasticity clay soils were encountered in the borings. These clay soils are generally medium stiff to very stiff in consistency and brown to dark brown with some reddish-brown mottling, in color. These clays generally contain varying amounts of calcareous and ferrous nodules. These clay strata extend to depths of 2 to 9 feet below existing grade.

Beneath the overburden high plasticity clay soils, bedrock strata of the undivided Grayson Marl and Main Street Limestone were encountered. Immediately below the overburden soil, either weathered limestone or weathered shale strata were encountered at depths ranging from about 2 to 8 feet at the time of our field investigation. The upper portions of the limestone and shale are differentially weathered, having been leached by percolating waters over time. The weathered limestone strata are typically soft to medium hard in rock hardness and tan in color. The zone of weathering extends to depths of approximately 5 to 13 feet.

Below the zone of differential weathering, dark gray and greenish gray shale was encountered. These strata are soft to medium hard in rock hardness and also contain occasional very thin silt seams. The top of the unweathered shale strata was encountered at 12.5 to 17 feet.

Groundwater

Seepage was encountered during drilling in three of the 11 borings at depths of 28.5, 22 and 6 feet in borings B5, B9 and B11 respectively. However, groundwater levels will fluctuate with seasonal and annual variations in rainfall, and also may vary as a result of development and landscape irrigation.

5.0 ENGINEERING ANALYSIS

Estimated Potential Vertical Movement (PVM)

Potential Vertical Movement (PVM) was evaluated utilizing several different methods for predicting movement, as described in Appendix B, and based on our experience and professional opinion. Specific information regarding final site elevations was not provided to this office at the time of this report.

At the time of our field investigation, the near-surface soils were generally found to be average to wet in moisture condition. Based on the information provided, the soils where shallow limestone was encountered are estimated to possess a PVM of about


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2 inches at the soil moisture conditions existing at the time of drilling. If the near surface soils are allowed to dry prior to or during construction, the potential for post-construction vertical movement could exceed 2.5 inches. Where shallow limestone was not encountered, the soils are estimated to possess a PVM of about 3 inches at the soil moisture conditions existing at the time of drilling. If the near surface soils are allowed to dry prior to or during construction, the potential for post-construction vertical movement could exceed 4 inches.

6.0 FOUNDATION RECOMMENDATIONS

The soils present within the building pads of the restrooms and pavilion structures have a potential for significant post-construction vertical movement with changes in soil moisture content. If post-construction movements on the order of 1 inch can be tolerated, it is our opinion that the new structures may be supported on either a shallow footing foundation system with a soil-supported floor slab or a slab-on-grade foundation system. These foundation types may be used after subgrade preparation is completed in accordance with the recommendations provided herein when bearing in reworked on-site clay soils. However, if such post-construction movements cannot be tolerated, a drilled shaft foundation system using either a soil-supported floor slab or a structurally-supported floor slab should be considered.

Recommendations for subgrade preparation to reduce potential post-construction movement are described in the Earthwork Section of this report. Please note that a soil-supported floor system may experience some vertical movement with changes in soil moisture content. Non-load bearing walls, partitions, and other elements bearing on the floor slab will reflect these movements should they occur. However, with appropriate design, adherence to good construction practices, and appropriate post-construction maintenance, these potential movements can be reduced.

We recommend the structural loads for stadium and field lighting be supported on auger-excavated, straight-sided, reinforced concrete drilled shafts founded in the unweathered dark gray shale encountered at a depths of about 12.5 to 17 feet. Weathered limestone was randomly occurring in a number of borings above the unweathered shale. Due to its inconsistency and high degree of weathering across the site it has been ignored as a bearing stratum for the pier supported structures.

Pedestrian bridges should be founded on drilled shafts. The diameter and depth will be controlled by axial loading and the stiffness of the bridge. If the bridge is flexible, and movements of up to 4 inches total and 2 inches differential is tolerable, we recommend a minimum 18-inch diameter shaft founded 10 feet below finished grade. If the bridges are rigid and cannot tolerate the movements, design should be as above for field lighting.

For standard monopole street lights less than 30-foot tall, should be founded on drilled shafts a minimum of 7 feet below finished grade.


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6.1 Shallow Footing Foundations

If potential post-construction movements on the order of those described above can be tolerated after earthwork preparation has been completed, a shallow footing foundation system may be utilized for support of the new structures. If a shallow foundation system is selected, we recommend that structural loads for the buildings be supported on reinforced concrete, monolithic shallow isolated or continuous footings founded at a depth of at least 26 inches below final exterior grade. Shallow footings should be designed for an allowable bearing capacity of 2,000 pounds per square foot. Continuous footings should be a minimum of 12 inches in width and isolated footings should be a minimum of 24 inches in width.

Footings may be earth-formed, but only if the sides can be cut and maintained vertically. In the event that sloughing occurs, or if the sides cannot be maintained vertically, grade beams should then be formed on both sides of the footing. If footings are formed, the exterior sides of the footings around the building should be carefully backfilled with on-site or imported clay soils. Backfill soils obtained from on-site should be compacted to at least 95 percent of the maximum dry density, as determined by ASTM D 698 (standard Proctor), and should be placed at a moisture content that is at least one percent (1%) above the optimum moisture content, as determined by the same test. Around the interior beams, the backfill soils should be placed as described in section 7.1.

All footings or footing segments should be constructed in a relatively seamless operation, with excavation activities and placement of the reinforcement steel and concrete occurring within the same day. In the event that concrete cannot be placed in the newly-excavated footings, the base of each excavated footing may be covered with a thin seal of lean concrete. We recommend a representative of D&S observe all footing excavations prior to placing concrete to verify bearing stratum competence. Any footing excavations left open overnight should be observed by D&S prior to placing concrete in order to determine the extent of stratum degradation and the amount of additional depth of excavation required.

6.1.1 Soil-Supported Floor System

A soil-supported floor system (floating slab) that is placed directly on the subgrade will be subject to minimal potential vertical movement resulting from subgrade soil volume changes, which may occur as a result of changes in soil moisture content. We recommend that the subgrade be prepared according to the Earthwork section of this report in order to reduce the potential for post-construction movement. The floor slab should be doweled to the beams at the locations of the doors in order to prevent vertical steps from forming at these high-traffic areas.


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6.1.2 Perimeter Moisture Barrier

In order to reduce the effects of seasonal moisture fluctuations and subsequent possible soil movement, consideration may be given to the installation of a vertical or horizontal barrier around the perimeter of the foundation. This barrier may be in the form of an independent barrier, such as a minimum 5-foot wide sidewalk. As an alternative, it may be possible to create an effective vertical moisture barrier by extending the outside perimeter grade beam to a depth of at least 5 feet beneath final grades.

Slab-on-Grade Foundation

As an alternative to a shallow footing foundation system, a slab-on-grade foundation may be used for this structure, with the soil prepared as described in the Earthwork Section of this report. A slab-on-grade foundation should be designed as a stiffened slab for the estimated heave and/or upward movement. The stiffened slab may be designed as either a conventionally-reinforced or a post-tensioned monolithic slab using the parameters developed in subsequent sections. We also recommend placing a moisture barrier, such as plastic sheeting, under the stiffened slab foundation to prevent the infiltration of moisture through the concrete slab.

6.2.1 Post-Tensioning Institute (PTI) Design Parameters

For a post-tensioned slab-on-grade foundation bearing in the on-site soils, the following PTI design parameters in Table 1 are recommended. These parameters were determined using Volflo Win 1.5 computer program from Geotechnical Tool Kit, Inc., are based on our analysis of the data developed, and have been modified based on our experience and engineering judgment regarding the site conditions and soil types present. These PTI Parameters have been determined based on the Post-Tensioning Manual 3rd Edition.

Table 1: PTI Design Parameters PARAMETER CENTER LIFT EDGE LIFT

Edge Moisture Variation, em

8.5 feet 5.0 feet

Estimated Differential Movement, ym (After soil

modification for a PVM of 1-inch)

-0.9 INCHES (SHRINK) +1.3 INCHES (SWELL)

6.2.2 PTI Design Assumptions:

Soil Bearing Capacity: 2,000 psf

Depth to Constant Suction: 10 feet


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Straight-sided Drilled Shafts

We recommend that structural loads for the pedestrian bridges and light poles be supported on auger-excavated, straight-sided, reinforced concrete drilled shafts founded in the unweathered dark gray shale encountered at depths of about 12.5 to 17 feet. We recommend those shafts penetrate a minimum of 3 feet into the unweathered shale to utilize the full amount of allowable end bearing. Drilled shafts may be designed to transfer imposed loads into the bearing stratum using a combination of end-bearing and skin friction.

We recommend straight-sided drilled piers for structural loads be a minimum of 18-inches in diameter and should be designed for an allowable end bearing and side friction as outlined in Table 2 below. The allowable side frictions noted in Table 2 may be taken from the top each stratum or from the bottom of any temporary casing used, whichever is deeper, to resist both axial loading and uplift. The allowable bearing values are summarized in Table 2 below.

Table 2. Drilled Shaft Allowable Bearing

Material Depth Below

Current Grades (ft) Allowable Side Friction (psf)

Allowable End Bearing (psf)

Dark Gray Shale 12.5 to 17 2,000 12,000

The shafts should be provided with sufficient steel reinforcement throughout their length to resist potential uplift pressures that will be exerted. For the near surface soils, these pressures are approximated to be on the order of 1,200 pounds psf of shaft area over an average depth of 10 feet. Often, 1/2 of a percent of steel by cross-sectional area is sufficient for this purpose (ACI 318). However, the final amount of reinforcement required should be determined based on the information provided herein, and should be the greater of that determination, or ACI 318.

There is no reduction in allowable capacities for shafts in proximity to each other. However for a two-shaft system, there is an 18 percent reduction in the available perimeter area for side friction capacity for shafts in contact (tangent). The area reduction can be extrapolated linearly to zero at one shaft diameter clear spacing. Please contact this office if other close proximity geometries need to be considered.

We anticipate that a straight-sided drilled pier foundation system designed and constructed in accordance with the information provided in this report will have a factor of safety in excess of 2.5 against shear failure and should limit potential movement to small fractions of an inch.

Lateral Loads

We have the following general recommendations for subsurface resistance to imposed lateral loads suitable for use in LPILE® or other lateral load software. These


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values are based on the stratigraphy observed and should be modeled as “Stiff Clay w/o Free Water”. However, it should be noted that there is subsurface variability across the project site and that some adjustments in the values provided may be required depending on the particular location. The depth ranges are average values based on the borings drilled.

Table 3. Lateral Load Parameters

Material Depth

Range (ft)Unit Wt. (pcf)

Undrained Cohesion (psf)

Strain Factor (ε50)

CLAY 0-4 120 500 0.02

CLAY 4-7 120 1,000 0.01

SHALE, highly weathered, lt gray

12-17 125 2,000 0.007

SHALE; dk gray 17+ 130 2,500 0.005

Drilled Shaft Construction Considerations

Seepage was encountered during drilling in three of the 11 borings at depths of approximately 28.5, 22 and 6 feet in borings B5, B9 and B11 respectively. However, groundwater levels may be anticipated to fluctuate with seasonal and annual variations in rainfall, and also may vary as a result of development and landscape irrigation.

We anticipate that temporary casing will be required at some of the shaft locations for the shaft installations, especially at the pedestrian bridges. Temporary casing should be available on-site if needed in the event that excessive sidewall sloughing occurs, or if excessive groundwater seepage is encountered that cannot be controlled with conventional pumps, sumps, or other means.

The installation of all drilled piers should be observed by experienced geotechnical personnel during construction to verify compliance with design assumptions including: 1) verticality of the shaft excavation, 2) identification of the bearing stratum, 3) minimum pier diameter and depth, 4) correct amount of reinforcement, 5) proper removal of loose material, and 6) that groundwater seepage, if present, is properly controlled.. D&S would be pleased to provide these services in support of this project.

During construction of the drilled shafts, care should be taken to avoid creating an oversized cap ("mushroom") near the ground surface that is larger than the shaft diameter. These “mushrooms” provide a resistance surface that near-surface soils can heave against. If near-surface soils are prone to sloughing, a condition which can result in “mushrooming”, the tops of the shafts should be formed in the sloughing soils using cardboard or other circular forms equal to the diameter of the shaft.


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Concrete used for the shafts should have a slump of 8 inches ± 1 inch. Individual shafts should be excavated in a continuous operation and concrete should be placed as soon as after completion of the drilling as is practical. All pier holes should be filled with concrete within 8 hours after completion of drilling. In the event of equipment breakdown, any uncompleted open shaft should be backfilled with soil to be redrilled at a later date. This office should be contacted when shafts have reached the target depth but cannot be completed.

7.0 EARTHWORK RECOMMENDATIONS

The near-surface soils present have an appreciable potential for post-construction vertical movement with changes in subsurface soil moisture changes. In order to limit Potential Vertical Movement to approximately 1 inch or less for shallow foundations and soil-supported slabs, we have the following recommendations for earthwork. Please note that more stringent tolerances limiting potential post-construction vertical movement will require more extensive rework.

Earthwork Preparation for the Building Pads

Strip the site of all vegetation, organic soil, and deleterious material within the building area. Typically, 6 inches is sufficient for this purpose.

After stripping the site, excavate the building pad areas to an additional depth of 2 feet and stockpile the excavated soil for possible re-use. Any additional excavation should extend at least 5 feet beyond the perimeter of the foundation.

After excavating and prior to placement of any grade-raise or re-work fill, scarify, rework, and recompact the exposed bottom of the excavated or stripped subgrade to a depth of 12 inches. The scarified and re-worked soils should be compacted to between 93 and 98 percent of the maximum dry density, as determined by ASTM D 698 (standard Proctor), and placed at a moisture content that is at least three (3) percentage points above the optimum moisture content, as determined by the same test.

Within 24 hours of recompacting the exposed subgrade, begin fill operations with the stockpiled excavated soil to no more than 12 inches below the bottom of floor slab final grade elevation. The reworked on-site soil fill should be placed in maximum 6-inch compacted lifts, compacted to between 93 and 98 percent of the maximum dry density, as determined by ASTM D 698 (standard Proctor), and placed at a moisture content that is at least three (3) percentage points or above its optimum moisture content, as determined by the same test.

Provide a minimum of 12 inches of select fill on top of the excavated surface. Select fill should have a liquid limit less than 40 and a plasticity index of between 6 and 18. The reworked or select fill should be placed in maximum 6-inch compacted lifts, compacted to at least 95 percent of the maximum density, as determined by ASTM D 698 (standard Proctor), and placed at a moisture


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content that is within three (3) percentage points of the optimum moisture content, as determined by the same test.

Place a minimum 10-mil thick vapor retarder beneath all floor slabs that will have coverings, such as tile, carpet, etc., or that will be painted.

Each lift of fill placed should be tested for moisture content and compaction by a testing laboratory, with a minimum of three (3) tests performed per lift of fill that is placed within the building pad footprint. D&S would be pleased to provide these services in support of this project.

Earthwork Preparation for the Soccer Fields

Across the football fields the surficial clays are either underlain with either weathered limestone or weathered shale. Each situation provides for a variable potential for post-construction vertical movement with changes in subsurface soil moisture changes on the order of 3 to 4 inches. We understand that the fields will be irrigated which will aid in keeping a relatively uniform moisture content and thereby limiting any movement. If desired, however, in order to limit Potential Vertical Movement to approximately 2 inches a 12-inch surface layer of select fill across the soccer fields may be provided. We have the following recommendations for earthwork.

Strip the site of all vegetation, organic soil, and deleterious material within the building area. Typically, 6 inches is sufficient for this purpose.

After excavating and prior to placement of any grade-raise or re-work fill, scarify, rework, and recompact the exposed bottom of the excavated or stripped subgrade to a depth of 12 inches. The scarified and re-worked soils should be compacted to at least 95 percent of the maximum dry density, as determined by ASTM D 698 (standard Proctor), and placed at a moisture content that is at or above the optimum moisture content, as determined by the same test.

Begin fill operations to final subgrade elevation. The fill should be placed in maximum 6-inch compacted lifts, compacted to a minimum of 95 percent of the maximum dry density, as determined by ASTM D 698 (standard Proctor), and placed at a moisture content that is at or above the optimum moisture content, as determined by the same test.

Field density tests should be performed at a minimum rate of one test per each 5,000 square feet, per lift, for all compacted fills.

Additional Considerations

In order to minimize the potential for post-construction vertical movement, consideration should be given to the following:

Trees or shrubbery with a mature height greater than 6 feet and/or that require excessive amounts of water should not be planted near structures.

Trees should not be planted closer than the mature tree’s height from structures.


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The grade should slope away from the foundation or soccer fields at minimum rate of five (5) percent within the first 10 feet of the foundation’s perimeter.

Water should not be allowed to pond next to the foundation. Rainfall roof runoff should be collected and conveyed to downspouts. Downspouts should be directed to discharge at least 5 feet away from the foundation

The moisture content of subgrade soils that are in proximity to the structure should be maintained as close as possible to a consistent level throughout the year. However, we strongly recommend that excessive watering near foundations be avoided.

8.0 PAVEMENT RECOMMENDATIONS

General

The pavement design recommendations provided herein are derived from the subgrade information obtained from our geotechnical investigation, as well as from design assumptions based on project information provided by the design team, our experience with similar projects in this area, and on the guidelines and recommendations of the American Concrete Pavement Association (ACPA). However, it is ultimately the responsibility of the Civil Engineer of Record and/or other design professionals who are responsible for pavement design to provide the final pavement design and associated specifications for this project.

Behavior of Soils beneath Pavement

The near-surface soils present have an appreciable potential for post-construction vertical movement with changes in soil moisture content. The edges of pavements and sidewalks are particularly prone to moisture variations and so these areas often exhibit the most distress. When cracks appear on the surface of the pavement, these openings can allow moisture to enter the pavement subgrade. The introduction of moisture can lead to soil movement and can ultimately result in additional weakening of the pavement section and accelerated failure of the pavement surface.

In order to minimize the potential impacts of soil movements on paved areas and to improve the long term performance of the pavement, we have the following recommendations:

Provide a crowned pavement, which provides maximum drainage away from the pavement (but away from structure foundations). A minimum slope of five (5) percent within the first 5 feet is considered ideal.

Subgrade treatments intended to reduce the soil’s potential for vertical movement or to increase the subgrade stability should to extend to at least 1 foot beyond the back of curbs or edges of pavements.

Avoid long areas of low-sloping roadway and adjust slopes to account for the Potential Vertical Movement.


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Pavement Subgrade Preparation

Considering the near-surface soil conditions present at the site, it is our opinion that lime treatment will be necessary to increase subgrade stability. To that end, we have the following recommendations for pavement subgrade preparation. As an alternative to lime treatment, a flexible base layer of a similar thickness may also be used.

Remove all surface vegetation, including tree root balls and root mats, and similar unsuitable materials from within the limits of the project. We anticipate a typical stripping depth of about 6inches.

Perform any cut operations as-needed. We anticipate that excavation of overburden soils can be accomplished with conventional earthwork equipment and methods.

After stripping, performing necessary cuts, the exposed subgrade should be proofrolled. Proofrolling consists of rolling the entire pavement subgrade with a heavily-loaded, tandem-axle dump truck weighing at least 20 tons or other approved equipment capable of applying similar loading conditions. Any soft, wet or weak soils that are observed to rut or pump excessively during proofrolling should be removed and replaced with well-compacted, on-site clayey material as outlined below. The proofrolling operation must be performed under the observation of a qualified geotechnical engineer. D&S would welcome the opportunity to perform these services for this project.

After proofrolling, all exposed surfaces should be scarified and reworked to a depth of 8 inches. The soils should then be recompacted to a minimum of 95 percent of the maximum dry density obtained in accordance with ASTM D 698 (standard Proctor), and to a moisture content that is at or above the material’s optimum moisture content, as determined by the same test.

In areas to receive fill, fill may be derived from on-site or may be imported. The fill should be placed in maximum 8-inch compacted lifts, compacted to at least 95 percent of the maximum dry density, as determined by ASTM D 698 (standard Proctor), and placed at a moisture content that is at or above the optimum moisture content, as determined by the same test. Prior to compaction, each lift of fill should first be processed throughout its thickness to break up and reduce clod sizes and blended to achieve a material of uniform density and moisture content. Once blended, compaction should be performed with a heavy tamping foot roller. Once compacted, if the surface of the embankment is too smooth, it may not bond properly with the succeeding layer. If this occurs, the surface of the compacted lift should be roughened and loosened by discing before the succeeding layer is placed.


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Water required to bring the fill material to the proper moisture content should be applied evenly through each layer. Any layers that become significantly altered by weather conditions should be reprocessed in order to meet recommended requirements. On hot or windy days, the use of water spraying methods may be required in order to keep each lift moist prior to placement of the subsequent lift. Furthermore, the subsurface soils should be kept moist prior to placing the pavement by water sprinkling or spraying methods.

Field density tests should be performed at a minimum rate of one test per each 5,000 square feet, per lift, for all compacted fills. The purpose of the field density testing is to provide some indication that uniform and adequate compaction is being obtained. The actual quality of the in-place fill and compaction methods should be the responsibility of the contractor, and tests that indicate satisfactory results should not be taken as a guarantee of the quality of the contractor's filling operations. Earthwork operations, including proofrolling, should be observed and tested on a continual basis by an experienced technician working under the supervision of a licensed geotechnical engineer.

Embankment materials should be placed on a properly prepared subgrade as outlined above. The combined excavation, placement, and spreading operation should be performed in such a manner as to obtain blending of the material, and to assure that, once compacted, the materials, will have the most practicable degree of compaction and stability. Materials obtained from on-site must be mixed and not segregated. Most importantly, sands should be blended with clays so that lifts will not consist of non-cohesive, sandy materials.

Soil imported from off-site sources should be tested for compliance with the recommendations herein and approved by the project geotechnical engineer prior to being used as fill. Imported materials shall consist of lean clays (maximum Plasticity Index of 32) that are essentially free of organic materials and particles larger than 4 inches in their maximum dimension.

Weathered limestone was encountered at a depth of 2 feet below present grade at Borings B1 and B2. If weathered limestone is encountered at final subgrade elevation, the weathered limestone should be undercut and replaced with compacted clay soil to a minimum depth of 8 inches.

8.3.1 Lime Treatment Recommendations

Once the subgrade is prepared, we have the following recommendations for preparation of the lime-treated subgrade:

For the lime stabilization, treat the prepared subgrade in accordance with TxDOT Item 260 to the elevations shown on the plans using an estimated five (5) percent hydrated lime by dry weight measure of the subgrade soil. However, the final amount of lime used should be determined once subgrade preparation is nearly complete. The amount of lime used should be sufficient to reduce the Plasticity Index of the soil to 15 or below


15

(Atterberg Lime series) or to increase pH of the soil-lime mixture to 12.4 (pH series). To account for error, an additional 1 to 2 percent lime should be added to these test quantities.

Hydrated lime should be applied such that mixing operations can be completed during the same working day.

The hydrated lime should be placed by the slurry method, meaning that the hydrated lime should be mixed with water in trucks or in tanks and applied as a thin water suspension or slurry.

The distributor truck or tank should be equipped with an agitator, which will maintain the lime and water in a uniform mixture. The material and hydrated lime should be thoroughly mixed by a rotary mixer or other device to obtain a homogeneous, friable mixture of material and lime that is free from clods and left to cure from one to four days.

Within our experience, we have found that a curing period of 48 to 72 hours is adequate. During the curing period, the material should be kept moist. After the specified “mellowing duration”, the soil-lime mixture should be remixed and tested for sufficient pulverization and mixing in accordance with TxDOT Item 260. After the required curing time, the material should be uniformly mixed using a rotary mixer capable of reducing the size of the particles so that, when all non-slaking aggregates (asphalt particles) retained on a no. 4 sieve are removed, the remainder of the material shall meet the following requirements when tested dry by laboratory sieves:

o Minimum passing 1-3/4" sieve: 100%

o Minimum passing No. 4 sieve: 60%

After sufficiently re-mixed, the soil and lime mixture should be compacted to a minimum of 98% of Standard Proctor (ASTM D 698) and to a moisture content that is at or above optimum moisture, as determined by the same test.

During the interval of time between application and mixing, the hydrated lime should not be exposed to the open air for a period exceeding six hours.

To reduce the potential for subgrade soil moisture changes at the edges of pavements, the lime stabilized subgrade should extend a minimum of 2 feet past the back of the roadway curbs or edge of asphalt.

Field density testing should be performed within all paving areas at the rate of one field density test for each 300 feet. These tests are necessary to determine if the recommended moisture and compaction requirements have been attained. After the required compaction is reached, the subgrade should be brought to the required lines and grades and finished


16

by rolling with a pneumatic tire or other suitable roller sufficiently light to prevent hairline cracking.

8.3.2 Soil Preparation – Flexible Base

Prepare the subgrade similar to that described for lime treatment.

Flexible base, should be Texas DOT Item 247, Type A, Grade 1 or 2. Flexible base material should be spread in six to eight inch loose horizontal lifts, and uniformly compacted to a minimum of 95% of the maximum standard Proctor dry density (ASTM D 698) and placed at a moisture content that is within three (±3) percentage points of the optimum moisture content as determined by that same test.

The area of flexible base should extend a minimum of one foot beyond the back of roadway curbs or edges of pavement.

Rigid Pavement

We recommend that reinforced Rigid Portland Cement Concrete for this site have a minimum thickness of 6 inches for all fire lanes and truck areas. A minimum thickness of 5 inches is recommended for automobile parking and plaza areas. The reinforced concrete paving should be placed over a minimum of 6 inches of lime treated subgrade soil for automobile parking and plaza areas and 8 inches for drives and fire lanes.

The following concrete mix design recommendations are as follows:

Recommended minimum design compressive strength: 3,500 psi.

15 to 20 percent fly ash may be used with the approval of the Civil Engineer of record

Curing compound should be applied within one hour of finishing operations

8.4.1 Pavement Joints and Cutting

The performance of concrete pavement depends to a large degree on the design, construction, and long term maintenance of concrete joints. The following recommendations and observations are offered for consideration by the Civil Engineer and/or pavement Designer-of-Record:

The concrete pavements should have adequately-spaced contraction joints to control shrinkage cracking. Past experience indicates that reinforced concrete pavements with sealed contraction joints on a 12 to 15-foot spacing, cut to a depth of one-quarter to one-third of the pavement thickness, have generally exhibited less uncontrolled post-construction cracking than pavements with wider spacing. The contraction joint pattern should divide the pavement into panels that


17

are approximately square where the panel length should not exceed 25 percent more than the panel width. Saw cut, post placement formed contraction joints should be saw cut as soon as the concrete can support the saw cutting equipment and personnel and before shrinkage cracks appear, on the order of 4 to 6 hours after concrete placement. Rubberized asphalt, silicone or other suitable flexible sealant could be used to seal the joints. Isolation joints should be used wherever the pavement will abut a structural element subject to a different magnitude of movement, e.g., light poles, retaining walls, existing pavement, stairways, entryway piers, building walls, or manholes.

In order to minimize the potential differential movement across the pavement areas described herein, all joints including contraction, isolation and construction joints should be sealed to minimize the potential for infiltration of surface water. Maintenance should include periodic inspection of these joints and resealed as necessary. The pavement should also be maintained properly, including the use of a flexible joint material to seal cracks as they degrade and open, which can occur during the life of the pavement.

9.0 CULVERTS

A drainage crossing will be required to the east of the soccer fields in the vicinity of borings B6 and B7 along the alignment of the eastern access drive. We anticipate that concrete rectangular culverts will be used. In order to prevent a hard point with reference to the road surfacing we recommend a minimum of 6 inches of compacted on-site clay soil be provided over the top of the culverts and beneath either the 8 inches of lime treatment or 8 inches of flexible base. . The on-site clay fill should be placed in maximum 8-inch compacted lifts, compacted to at least 95 percent of the maximum dry density, as determined by ASTM D 698 (standard Proctor), and placed at a moisture content that is at or above the optimum moisture content, as determined by the same test.

Lateral Pressures

The culverts will be subjected to lateral earth pressures and should be designed in consideration of these forces. Earth pressures will be influenced by structural design of the walls, conditions of wall restraint, methods of construction and/or compaction, the strength of the materials being restrained, and drainage conditions.

The "at-rest" condition assumes that no wall rotation or movement will occur which is the case for culverts. The design lateral earth pressures recommended herein do not include a Factor of Safety and do not provide for hydrostatic pressures or dynamic pressures on the walls. Lateral loads due to surcharge should be calculated as shown in Table 4. These loads need to be considered where appropriate. A minimum surcharge value of 250 pounds per square foot should be used.


18

Table 4. Lateral Earth Pressures

Earth Pressure

Conditions

Coefficient for Backfill Type

Equivalent Fluid Density

(pcf)

Surcharge Pressure

(psf)

Earth Pressure

(psf)

At-Rest (Ko) On-Site Clayey

Soils - 0.67 83 (0.67) S1 (83) H2

Notes: (1) S = surcharge pressure (2) H = wall height

Applicable conditions to Table 4 above include:

Uniform surcharge, where S is surcharge pressure

A maximum in situ soil total unit weight of 125 pcf

Horizontal backfill, compacted as described in later sections

No loading contribution from compaction equipment

Hydrostatic pressure should be added to the pressures shown in Table 4.

Design and Construction Considerations

To calculate the resistance to sliding, a value of 0.35 should be used as the ultimate coefficient of friction. Preparation of the base should be as described in the Pavements Section.

On-site clayey soil backfill should be placed in 6-inch thick loose layers and should be compacted as noted above. The backfill directly behind the walls should be compacted with light, hand-held compactors or vibratory plates. Heavy compactors and grading equipment should not be allowed to operate within 5 feet of the walls during backfilling to avoid developing excessive temporary or long-term lateral soil pressures.

Scour Potential

Consideration should be given to streambed erosion protection and bank erosion protection on both sides of the roadway. Streambed erosion may be accomplished with gabion mattresses and gabions for bank erosion.

10.0 SEISMIC CONSIDERATION

North Central Texas is generally regarded as an area of low seismic activity. Based on the boring log data and general geologic information gathered, we recommend that Soil Site Class “C” be used at this site.


19

11.0 LIMITATIONS

The professional geotechnical engineering services performed for this project, the findings obtained, and the recommendations prepared were accomplished in accordance with currently accepted geotechnical engineering principles and practices.

Variations in the subsurface conditions are noted at the specific boring locations for this study. As such, all users of this report should be aware that differences in depths and thicknesses of strata encountered can vary between the boring locations. Statements in the report as to subsurface conditions across the site are extrapolated from the data obtained at the specific boring locations. The number and spacing of the exploration borings were chosen to obtain geotechnical information for the design and construction of a lightly-loaded residential structure foundation. If there are any conditions differing significantly from those described herein, D&S should be notified to re-evaluate the recommendations contained in this report.

Recommendations contained herein are not considered applicable for an indefinite period of time. Our office must be contacted to re-evaluate the contents of this report if construction does not begin within a one year period after completion of this report.

The scope of services provided herein does not include an environmental assessment of the site or investigation for the presence or absence of hazardous materials in the soil, surface water, or groundwater.

All contractors referring to this geotechnical report should draw their own conclusions regarding excavations, construction, etc. for bidding purposes. D&S is not responsible for conclusions, opinions or recommendations made by others based on these data. The report is intended to guide preparation of project specifications and should not be used as a substitute for the project specifications.

Recommendations provided in this report are based on our understanding of information provided by the Client to us regarding the scope of work for this project. If the Client notes any differences, our office should be contacted immediately since this may materially alter the recommendations.

APPENDIX A - BORING LOGS AND SUPPORTING DATA

B10

B1

B4

RINEY RD

B11

B3

B5

Project #16-0009

B2

U

S

H

W

Y

7

7

B8

B7

B6

B9

RINEY RD

Project #16-0009

KEY TO SYMBOLS AND TERMS

CONSISTENCY: FINE GRAINED SOILS

CONDITION OF SOILS

SECONDARY COMPONENTS

WEATHERING OF ROCK MASS

TCP (#blows/ft)

< 88 - 20

20 - 6060 - 100

> 100

Relative Density (%)

0 - 1515 - 35

35 - 6565 - 85

85 - 100

SPT (# blows/ft)

0 - 23 - 4

5 - 89 - 15

16 - 30

> 30

UCS (tsf)

< 0.250.25 - 0.5

0.5 - 1.01.0 - 2.0

2.0 - 4.0

> 4.0

CONSISTENCY OF SOILSLITHOLOGIC SYMBOLS

CONDITION: COARSE GRAINED SOILS

QUANTITY DESCRIPTORS

RELATIVE HARDNESS OF ROCK MASS

SPT (# blows/ft)

0 - 45 - 10

11 - 3031 - 50

> 50

DescriptionNo visible sign of weatheringPenetrative weathering on open discontinuity surfaces,but only slight weathering of rock materialWeathering extends throughout rock mass, but the rockmaterial is not friableWeathering extends throughout rock mass, and the rockmaterial is partly friableRock is wholly decomposed and in a friable condition butthe rock texture and structure are preservedA soil material with the original texture, structure, andmineralogy of the rock completely destroyed

DesignationFreshSlightly weathered

Moderately weathered

Highly weathered

Completely weathered

Residual Soil

DescriptionCan be carved with a knife. Can be excavated readily withpoint of pick. Pieces 1" or more in thickness can be brokenby finger pressure. Readily scratched with fingernail.Can be gouged or grooved readily with knife or pick point.Can be excavated in chips to pieces several inches in sizeby moderate blows with the pick point. Small, thin piecescan be broken by finger pressure.Can be grooved or gouged 1/4" deep by firm pressure onknife or pick point. Can be excavated in small chips topieces about 1" maximum size by hard blows with the pointof a pick.Can be scratched with knife or pick. Gouges or grooves 1/4"deep can be excavated by hard blow of the point of a pick.Hand specimens can be detached by a moderate blow.Can be scratched with knife or pick only with difficulty.Hard blow of hammer required to detach a hand specimen.Cannot be scratched with knife or sharp pick. Breaking of handspecimens requires several hard blows from a hammer or pick.

TraceFewLittleSomeWith

DesignationVery Soft

Soft

Medium Hard

Moderately Hard

Hard

Very Hard

< 5% of sample5% to 10%10% to 25%25% to 35%> 35%

Condition

Very LooseLoose

Medium DenseDense

Very Dense

Consistency

Very SoftSoft

Medium StiffStiff

Very Stiff

HardAR

TIF

ICIA

L

Asphalt

Aggregate Base

Concrete

Fill

SO

ILR

OC

K

Limestone

Mudstone

Shale

Sandstone

Weathered Limestone

Weathered Shale

Weathered Sandstone

CH: High Plasticity Clay

CL: Low Plasticity Clay

GP: Poorly-graded Gravel

GW: Well-graded Gravel

SC: Clayey Sand

SP: Poorly-graded Sand

SW: Well-graded Sand

2.0 ft

6.0 ft

10.0 ft

CLAY (CL); medium stiff to very stiff;dark brown; trace ferrous nodules androotsLIMESTONE; moderately to highlyweathered; soft; tan

SHALE; highly weathered; very soft;light gray, greenish gray; occasionalhighly cemented layers; tracelimestone fragments; some silt

End of boring at 10.0'

Notes:-dry during drilling-dry upon completion

29 121721.1

27.4

1.0

4.5+

4.5+

2.75

4.5+

3.5

7,7

S

S

T

S

S

S

S

Atterberg Limits

Clay(%)

B1PAGE 1 OF 1

Legend: S-Shelby Tube N-Standard Penetration T-Texas Cone Penetration C-Core B-Bag Sample - Water Encountered

REC(%)

RQD(%)

Swell(%)LL

(%) PI

TotalSuction

(pF)

Passing#200Sieve(%)

BORING LOG

GraphicLog PL

(%)

Unconf.Compr.Str (ksf)

DUW(pcf)

MC(%)

Depth(ft)

0

5

10

15

20

25

30

35

40

HandPen. (tsf)

orSPTor

TCP

HandPen. (tsf)

orSPTor

TCP

SampleType

CLIENT: Denton Parks and Recreation Department

LOCATION: Denton, TexasPROJECT: Vela Athletic Complex

DRILLED BY: Kevin Kavadas (D&S)

START DATE: 1/14/2016 DRILL METHOD: Hollow Stem Flight Auger

LOGGED BY: Ricky Ybarra (D&S)

FINISH DATE: 1/14/2016

GROUND ELEVATION:

GPS COORDINATES: N33.24876, W97.15259

PROJECT NUMBER: 16-0009

2.0 ft

5.0 ft

10.1 ft

CLAY (CL); very stiff; reddish brown;occasional limestone pocket; tracecalcareous nodules, shell fragmentsand rootsLIMESTONE; highly weathered; verysoft; tan

LIMESTONE; medium hard to hard;tan



31 102112.7

27.8

4.5+

4.5+

4.5+

4.0

50=2.0"50=3.0"

50=0.5"50=0.25"

S

S

S

S

T

T

Atterberg Limits

Clay(%)

B2PAGE 1 OF 1


REC(%)

RQD(%)

Swell(%)LL

(%) PI

TotalSuction

(pF)

Passing#200Sieve(%)

BORING LOG

GraphicLog PL

(%)


DUW(pcf)

MC(%)

Depth(ft)

0

5

10

15

20

25

30

35

40

HandPen. (tsf)

orSPTor

TCP

HandPen. (tsf)

orSPTor

TCP

SampleType







GROUND ELEVATION:



4.0 ft

6.0 ft

17.0 ft

25.4 ft

CLAY (CH); dark brown; tracecalcareous nodules, ferrous nodulesand roots

CLAY (CH); dark brown; withlimestone fragments

SHALE; highly weathered; very soft;greenish gray, light gray; occasionallimestone seam; occasional highlycemented layer

SHALE; soft to medium hard; darkgray; occasional extremely thin siltseams; trace mudstone and shellfragments



57

41

35

26

22

15

12.9

16.4

14.1

9.2

101.5

120.5

124.8

114.2

19.6

13.9

12.2

17.2

16.4

1.5

4.0

4.5+

4.5+

4.5+

4.5+

4.5+

4.5+

4.5+

4.5+

50=2.5"50=2.25"

S

S

S

S

S

S

S

S

S

S

T

Atterberg Limits

Clay(%)

B3PAGE 1 OF 1


REC(%)

RQD(%)

Swell(%)LL

(%) PI

TotalSuction

(pF)

Passing#200Sieve(%)

BORING LOG

GraphicLog PL

(%)


DUW(pcf)

MC(%)

Depth(ft)

0

5

10

15

20

25

30

35

40

HandPen. (tsf)

orSPTor

TCP

HandPen. (tsf)

orSPTor

TCP

SampleType







GROUND ELEVATION:



3.0 ft

5.0 ft

12.0 ft

17.0 ft

35.3 ft

CLAY (CH); stiff to very stiff; reddishbrown; ferrous nodules

LIMESTONE; highly weathered; verysoft; tan; trace clay and silt

LIMESTONE; medium hard to hard;tan

SHALE; moderately weathered; verysoft; light gray, greenish gray;occasional highly cemented layers;occasional extremely thin silt seams;

SHALE; soft to medium hard; darkgray; occasional extremely thin siltseams; trace shell fragments



2.1

72 3834

8.1

6.7

87.3

116.4

114.4

29.7

36.0

14.9

15.6

16.4

23.6

3.5

4.5+

3.5

2.5

4.5+

4.5+

50=0.0"50=0.0"

50=0.125"50=0.25"

50=1.0"50=1.5"

50=2.75"50=2.0"

50=2.5"50=1.0"

S

S

S

S

T

T

S

S

T

T

T

Atterberg Limits

Clay(%)

B4PAGE 1 OF 1


REC(%)

RQD(%)

Swell(%)LL

(%) PI

TotalSuction

(pF)

Passing#200Sieve(%)

BORING LOG

GraphicLog PL

(%)


DUW(pcf)

MC(%)

Depth(ft)

0

5

10

15

20

25

30

35

40

HandPen. (tsf)

orSPTor

TCP

HandPen. (tsf)

orSPTor

TCP

SampleType







GROUND ELEVATION:



4.0 ft

10.0 ft

17.0 ft

35.3 ft

CLAY (CH); medium stiff to very stiff;brown, reddish brown mottling; someferrous nodules

LIMESTONE; moderately to highlyweathered; soft to medium hard; tan

SHALE; highly weathered; very soft;light gray, greenish gray; occasionalhighly cemented layers; occasionalextremely thin silt seams;



Notes:-water at 28.5 feet during drilling

1.651 2625

9.8

3.6

104.3

123.4

106.0

28.7

22.9

36.5

13.6

21.4

19.4

19.3

1.5

2.5

3.75

2.75

4.5+

4.5+

4.5+

35,50=1.5"

20,32

50=3.5"50=2.25"

50=2.0"50=0.5"

S

S

S

S

T

S

S

S

T

T

T

Atterberg Limits

Clay(%)

B5PAGE 1 OF 1


REC(%)

RQD(%)

Swell(%)LL

(%) PI

TotalSuction

(pF)

Passing#200Sieve(%)

BORING LOG

GraphicLog PL

(%)


DUW(pcf)

MC(%)

Depth(ft)

0

5

10

15

20

25

30

35

40

HandPen. (tsf)

orSPTor

TCP

HandPen. (tsf)

orSPTor

TCP

SampleType







GROUND ELEVATION:



6.0 ft

9.0 ft

17.0 ft

35.4 ft

CLAY (CH); medium stiff to verystiff; dark brown; trace calcareous,ferrous nodules and roots;

CLAY (CH); medium stiff to very stiff;dark brown; few limestone pockets;some silt; trace calcaeous nodules

SHALE; highly weathered; light gray,greenish gray; occasional extremelythin silt seams; with limestone pockets




54 3618

2.4

3.7

5.7

100.8

105.1

108.6

25.6

24.8

23.8

18.8

15.4

1.5

1.5

3.5

2.5

2.75

2.75

4.25

1.5

4.5+

4.5+

4.5+

4.5+

50=2.5"50=1.75"

50=0.5"50=0.75"

50=2.0"50=2.25"

S

S

S

S

S

S

S

S

S

S

S

S

T

T

T

Atterberg Limits

Clay(%)

B6PAGE 1 OF 1


REC(%)

RQD(%)

Swell(%)LL

(%) PI

TotalSuction

(pF)

Passing#200Sieve(%)

BORING LOG

GraphicLog PL

(%)


DUW(pcf)

MC(%)

Depth(ft)

0

5

10

15

20

25

30

35

40

HandPen. (tsf)

orSPTor

TCP

HandPen. (tsf)

orSPTor

TCP

SampleType







GROUND ELEVATION:



4.0 ft

7.0 ft

17.0 ft

26.0 ft

CLAY WITH SAND (CH); soft to verystiff; dark brown; trace calcerous andferrous nodules

CLAY (CH); very stiff; dark brown;with limestone fragments; tracecalcareous nodules

SHALE; highly weathered; very soft;light gray, greenish gray; occasionallimestone seam; occasional extremelythin silt seams

SHALE; soft; dark gray; occasionalhighly cemented layers; occasionalextremely thin silt seams; trace shellfragments



1.151 33 7918

3.3

101.9

100.5

25.2

23.8

30.3

18.8

0.5

1.5

2.0

3.5

4.5+

4.5+

3.5

4.5+

4.5+

4.5+

4.5+

4.5+

S

S

S

S

S

S

S

S

S

S

S

S

Atterberg Limits

Clay(%)

B7PAGE 1 OF 1


REC(%)

RQD(%)

Swell(%)LL

(%) PI

TotalSuction

(pF)

Passing#200Sieve(%)

BORING LOG

GraphicLog PL

(%)


DUW(pcf)

MC(%)

Depth(ft)

0

5

10

15

20

25

30

35

40

HandPen. (tsf)

orSPTor

TCP

HandPen. (tsf)

orSPTor

TCP

SampleType







GROUND ELEVATION:



4.0 ft

6.0 ft

13.0 ft

30.2 ft

CLAY (CH); medium stiff to very stiff;dark brown; trace calcareous andferrous nodules; trace silt

CLAY (CH); medium stiff to stiff; darkbrown; with limeston fragments

SHALE; highly weathered; very soft;light gray, greenish gray; occasioanalhighly cemented layers; occasionalextremely thin silt seams

SHALE; soft to medium hard; darkgray; occasional very thin silt seams;thrace mudstone fragmennts; traceshell fragments



1.0

2.5

3.0

3.5

3.0

1.5

4.5+

3.5

4.5+

4.5+

27,28

50=5.5"50=3.75"

50=1.0"50=1.0"

S

S

S

S

S

S

S

S

S

S

T

T

T

Atterberg Limits

Clay(%)

B8PAGE 1 OF 1


REC(%)

RQD(%)

Swell(%)LL

(%) PI

TotalSuction

(pF)

Passing#200Sieve(%)

BORING LOG

GraphicLog PL

(%)


DUW(pcf)

MC(%)

Depth(ft)

0

5

10

15

20

25

30

35

40

HandPen. (tsf)

orSPTor

TCP

HandPen. (tsf)

orSPTor

TCP

SampleType







GROUND ELEVATION:



4.0 ft

6.0 ft

13.0 ft

26.0 ft

CLAY (CH); stiff; dark brown; tracecalcareous nodule; trace silt

CLAY (CH); very hard; dark brown;with limestone fragments

SHALE; highly weathered; very soft;light gray, greenish gray; occasionalhighly cemented layers; occcasionalextremely thin silt seams

SHALE; soft to medium hard; darkgray; occasional very thin silt seams;mudstone fragments, trace shellfragments


Notes:-water at 22 feet during drilling

1.150 32 7318

7.6

103.7

117.2

24.1

22.1

16.4

2.0

3.0

3.0

3.25

4.0

4.5+

4.5+

4.5+

4.5+

4.5+

4.5+

19,17

S

S

S

S

T

S

S

S

S

S

S

S

Atterberg Limits

Clay(%)

B9PAGE 1 OF 1


REC(%)

RQD(%)

Swell(%)LL

(%) PI

TotalSuction

(pF)

Passing#200Sieve(%)

BORING LOG

GraphicLog PL

(%)


DUW(pcf)

MC(%)

Depth(ft)

0

5

10

15

20

25

30

35

40

HandPen. (tsf)

orSPTor

TCP

HandPen. (tsf)

orSPTor

TCP

SampleType







GROUND ELEVATION:



3.5 ft

10.0 ft

12.5 ft

30.2 ft

CLAY (CH); stiff to very stiff; darkbrown to brown; trace ferrous nodules

LIMESTONE; highly weathered; verysoft, occasionally hard; light brown;highly argillaceous

SHALE; highly weathered; very soft;light brown; fissile

SHALE; soft to medium hard; darkgray; fissile



52 2824

21.7

24.7

25.1

2.5

3.0

2.5

4.5+

4.5+

35,34

27,11

47,50=4.5"

50=5.0"50=3.0"

50=1.75"50=0.5"

S

S

S

S

T

T

S

T

T

T

Atterberg Limits

Clay(%)

B10PAGE 1 OF 1


REC(%)

RQD(%)

Swell(%)LL

(%) PI

TotalSuction

(pF)

Passing#200Sieve(%)

BORING LOG

GraphicLog PL

(%)


DUW(pcf)

MC(%)

Depth(ft)

0

5

10

15

20

25

30

35

40

HandPen. (tsf)

orSPTor

TCP

HandPen. (tsf)

orSPTor

TCP

SampleType





LOGGED BY: Patritzia Kolarova (D&S)


GROUND ELEVATION:



1.0 ft

9.0 ft

16.0 ft

CLAY (CH); stiff; reddish brown, darkbrown; few limestone pockets; traceferrous nodulesLIMESTONE; moderately to highlyweathered;soft to medium hard; lightbrown, tan; highly argillaceous; someclay

SHALE; moderately to highlyweathered; very soft to soft; dark gray


Notes:-water at 6 feet during drilling

3.0

4.0

29,50=1.5"

14,23

50=5.5",45

S

S

T

T

T

Atterberg Limits

Clay(%)

B11PAGE 1 OF 1


REC(%)

RQD(%)

Swell(%)LL

(%) PI

TotalSuction

(pF)

Passing#200Sieve(%)

BORING LOG

GraphicLog PL

(%)


DUW(pcf)

MC(%)

Depth(ft)

0

5

10

15

20

25

30

35

40

HandPen. (tsf)

orSPTor

TCP

HandPen. (tsf)

orSPTor

TCP

SampleType







GROUND ELEVATION:



B-4 2-3 36.0 38.6 391 2.1

B-5 2-3 22.9 26.2 390 1.6

B-7 2-3 25.2 26.1 395 1.1

B-9 2-3 24.1 24.6 391 1.1

BoringNumber

Depthfeet

Applied Pressure,psf

Vertical Swell, %

SWELL TEST RESULTS

Final MoistureContent, %

Initial MoistureContent, %

CLIENT: Denton Parks and Recreation DepartmentPROJECT: Vela Athletic Complex

PROJECT NUMBER: 16-0009 LOCATION: North Lakes Park, Denton, Texas

APPENDIX B - GENERAL DESCRIPTION OF PROCEDURES


ANALYTICAL METHODS TO PREDICT MOVEMENT

INDEX PROPERTY AND CLASSIFICATION TESTS

Index property and classification testing is perhaps the most basic, yet fundamental tool available for predicting potential movements of clay soils. Index property testing typically consists of moisture content, Atterberg Limits, and Grain-size distribution determinations. From these results a general assessment of a soil’s propensity for volume change with changes in soil moisture content can be made.

Moisture Content

By studying the moisture content of the soils at varying depths and comparing them with the results of Atterberg Limits, one can estimate a rough order of magnitude of potential soil movement at various moisture contents, as well as movements with moisture changes. These tests are typically performed in accordance with ASTM D 2216.

Atterberg Limits

Atterberg limits determine the liquid limit (LL), plastic limit (PL), and plasticity index (PI) of a soil. The liquid limit is the moisture content at which a soil begins to behave as a viscous fluid. The plastic limit is the moisture content at which a soil becomes workable like putty, and at which a clay soil begins to crumble when rolled into a thin thread (1/8” diameter). The PI is the numerical difference between the moisture constants at the liquid limit and the plastic limit. This test is typically performed in accordance with ASTM D 4318.

Clay mineralogy and the particle size influence the Atterberg Limits values, with certain minerals (e.g., montmorillonite) and smaller particle sizes having higher PI values, and therefore higher movement potential.

A soil with a PI below about 15 to 18 is considered to be generally stable and should not experience significant movement with changes in moisture content. Soils with a PI above about 30 to 35 are considered to be highly active and may exhibit considerable movement with changes in moisture content.

Fat clays with very high liquid limits, weakly cemented sandy clays, or silty clays are examples of soils in which it can be difficult to predict movement from index property testing alone.

Grain-size Distribution

The simplest grain-size distribution test involves washing a soil specimen over the No. 200 mesh sieve with an opening size of 0.075 mm (ASTM D 1140). This particle size has been defined by the engineering community as the demarcation between coarse-grained and fine-grained soils. Particles smaller than this size can be further distinguished between silt-size and clay-size particles by use of a Hydrometer test (ASTM D 422). A more complete grain-size distribution test that uses sieves to relative amount of particles according is the Sieve Gradation Analysis of Soils (ASTM D 6913). Once the characteristics of the soil are determined through classification testing,


a number of movement prediction techniques are available to predict the potential movement of the soils. Some of these are discussed in general below.

TEXAS DEPARTMENT OF TRANSPORTATION METHOD 124-E

The Texas Department of Transportation (TxDOT) has developed a generally simplistic method to predict movements for highways based on the plasticity index of the soil. The TxDOT method is empirical and is based on the Atterberg limits and moisture content of the subsurface soil. This method generally assumes three different initial moisture conditions: dry, “as-is”, and wet. Computation of each over an assumed depth of seasonal moisture variation (usually about 15 feet or less) provides an estimate of potential movement at each initial condition. This method requires a number of additional assumptions to develop a potential movement estimate. As such, the predicted movements generally possess large uncertainties when applied to the analysis of conditions under building slabs and foundations. In our opinion, estimates derived by this method should not be used alone in determination of potential movement.

SWELL TESTS

Swell tests can lead to more accurate site specific predictions of potential vertical movement by measuring actual swell volumes at in situ initial moisture contents. One-dimensional swell tests are almost always performed for this measurement. Though swell is a three-dimensional process, the one-dimensional test provides greatly improved potential vertical movement estimates than other methods alone, particularly when the results are “weighted” with respect to depth, putting more emphasis on the swell characteristics closer to the surface and less on values at depth.


POTENTIAL VERTICAL MOVEMENT

A general index for movement is known as the Potential Vertical Rise (PVR). The actual term PVR refers to the TxDOT Method 124-E mentioned above. For the purpose of this report the term Potential Vertical Movement (PVM) will be used since PVM estimates are derived using multiple analytical techniques in addition to TxDOT methods.

It should be noted that all slabs and foundations constructed on clay or clayey soils have at least some risk of potential vertical movement that can result from to changes in soil moisture contents. To eliminate that risk, slabs and foundation elements (e.g., grade beams) should be designed as structural elements physically separated by some distance from the subgrade soils (usually 6 to 12 inches).

In some cases, a floor slab with movements as little as 1/4 of an inch may result in damage to interior walls, such as cracking in sheet rock or masonry walls, or separation of floor tiles. However, these cracks are often minor and most people consider them 'liveable'. In other cases, movement of 1 inch may cause significant damage, inconvenience, or even create a hazard (trip hazard or others).

Vertical movement of clay soils under slab-on-grade foundations resulting from soil moisture changes can stem from a variety causes, including poor site grading and drainage, improperly prepared subgrade, trees and large shrubbery located too close to structures, utility leaks or breaks, poor subgrade maintenance such as inadequate or excessive irrigation, or other causes.

PVM is generally considered to be a measurement of the change in height of a foundation from the elevation it was originally placed. Experience and generally accepted practice suggests that if the PVM of a site is less than one inch, the associated differential movement will be minor and acceptable to most people.

SETTLEMENT

Settlement is a measure of a downward movement due to consolidation of soil. This can occur from improperly placed fill (uncompacted or under-compacted), loose native soil, or from large amounts of unconfined sandy material. Properly compacted fill may settle approximately one (1) percent of its depth, particularly when fill depths exceed 10 feet.


EDGE AND CENTER LIFT MOVEMENT (ym)

The Post-Tensioning Institute (PTI) has developed a parameter of movement defined as the differential movement (ym) estimated using the change in soil surface elevation in two locations separated by a distance em within which the differential movement will occur; em being measured from the exterior of a building to some distance toward the interior. All calculations for this report are based on the modified PTI procedure in addition to our judgment as necessary for specific site conditions. The minimum movements given in the PTI are for climatic conditions only and have been modified somewhat to account for site conditions which may increase the actual parameters.

“Center lift” occurs when the center, or some portion of the center of the building, is higher than the exterior. This can occur when the soils around the exterior shrink and/or when the soils under the center of the building swell.

“Edge lift” occurs when the edge, or some portion of the exterior of the building, is higher than the center. This can occur when the soils around the exterior of the building swell. It is not uncommon to have both the center lift and the edge lift phenomena occurring on the different areas of the same building.


SPECIAL COMMENTARY ON CONCRETE AND EARTHWORK

RESTRAINT TO SHRINKAGE CRACKS

One of the characteristics of concrete is that during the curing process shrinkage occurs and if there are any restraints to prevent the concrete from shrinking, cracks can form. In a typical slab-on-grade or structurally-suspended foundation, there will be cracks resulting from interior beams and piers that restrict shrinkage. This restriction is called Restraint to Shrinkage (RTS). In post tensioned slabs, the post tensioning strands are slack when installed and must be stressed at a later time. The best procedure is to stress the cables approximately 30 percent within one to two days of placing the concrete. The cables are stressed fully when the concrete reaches greater strength, usually in 7 days. During this time before the cables are stressed fully, the concrete may crack more than conventionally reinforced slabs. However, when the cables are stressed, some of the cracks will pull together. These RTS cracks do not normally adversely affect the overall performance of the foundation. It should be noted that for exposed floors, especially those that will be painted, stained or stamped, these cracks may be aesthetically unacceptable. Any tile which is applied directly to concrete or over a mortar bed over concrete has a high probability of minor cracks occurring in the tile due to RTS. If tiles are used, it is recommended that expansion joints are installed in appropriate locations in order to minimize these cracks.

UTILITY TRENCH EXCAVATION

Trench excavation for utilities should be sloped or braced in the interest of safety. Attention is drawn to OSHA Safety and Health Standards (29 CFR 1926/1910), Subpart P, regarding trench excavations greater than 5 feet in depth.

FIELD SUPERVISION AND DENSITY TESTING

Field density and moisture content determinations should be made on each lift of fill at a minimum rate of three (3) tests per lift in the building pad area, one (1) test per lift per 3,000 square feet in other fill areas, and one (1) test lift per 100 linear feet of utility trench backfill. Supervision by the field technician and the project engineer is required. Some adjustments in the test frequencies may be required based upon the general fill types and soil conditions at the time of fill placement.

It is recommended that all site and subgrade preparation, proofrolling, and pavement construction be monitored by a qualified engineering firm. Density tests should be performed to verify proper compaction and moisture content of any earthwork. Inspection should be performed prior to and during concrete placement operations. To that end, D&S would be pleased to assist you on this project.

14805 Trinity Boulevard, Fort Worth, Texas 76155

Geotechnical 817.529.8464 Corporate 940.735.3733

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