geotechnical engineering study for vista … package 26/rki final geotechnical... · vista ridge...

GEOTECHNICAL ENGINEERING STUDY

FOR

VISTA RIDGE PIPELINE - REGIONAL SUPPLY INTERMEDIATE PUMP STATION NO. 1

BASTROP COUNTY, TEXAS

GEOTECHNICAL ENGINEERING STUDY

For

VISTA RIDGE PIPELINE – REGIONAL SUPPLY

INTERMEDIATE PUMP STATION NO. 1 BASTROP COUNTY, TEXAS

Prepared for

VRRSP Consultants, LLC. San Antonio, Texas

Prepared by

RABA KISTNER CONSULTANTS, INC. San Antonio, Texas

PROJECT NO. ASA15-051-00

October 27, 2016

Project No. ASA15-051-00 October 27, 2016

TABLE OF CONTENTS

i

INTRODUCTION ....................................................................................................................................... 1

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

LIMITATIONS ........................................................................................................................................... 1

BORINGS AND LABORATORY TESTS ......................................................................................................... 2

CORROSIVITY TESTING .................................................................................................................................. 3 Ductile Iron Pipe ..................................................................................................................................... 3 Cement Type ........................................................................................................................................... 3

GEOPHYSICAL TESTING FOR DYNAMIC SOIL PROPERTIES ........................................................................... 3

PHOTOIONIZATION DETECTOR AND CUMBUSTIBLE GAS INDICATOR SCREENING RESULTS ..................... 4

GENERAL SITE CONDITIONS ..................................................................................................................... 5

SITE DESCRIPTION ......................................................................................................................................... 5

GEOLOGY ....................................................................................................................................................... 5

SEISMIC COEFFICIENTS .................................................................................................................................. 5

STRATIGRAPHY .............................................................................................................................................. 6

GROUNDWATER ............................................................................................................................................ 6

EXPANSIVE SOIL RELATED MOVEMENTS .................................................................................................. 7

SITE GRADING ................................................................................................................................................ 7

EXPANSIVE SOIL-RELATED MOVEMENTS ..................................................................................................... 7

Facility Pad PVR Reduction Options ............................................................................................................. 7

FOUNDATION RECOMMENDATIONS ..................................................................................................... 10

STORAGE TANK FOUNDATION .................................................................................................................... 11 Tank Pre-Loading Recommendations .................................................................................................. 11

FACILITY FOUNDATION OPTIONS ............................................................................................................... 12

SHALLOW FOUNDATIONS ........................................................................................................................... 13 Net Allowable Bearing Capacity ........................................................................................................... 13 Uplift Resistance ................................................................................................................................... 13 Lateral Resistance ................................................................................................................................. 13 Area Flatwork and Floor Slabs ............................................................................................................. 13

DEEP FOUNDATIONS ................................................................................................................................... 14 Pier Shaft Potential Uplift Forces ......................................................................................................... 14

DRILLED-AND-UNDERREAMED PIERS ......................................................................................................... 14 Allowable Uplift Resistance .................................................................................................................. 14

DRILLED, STRAIGHT-SHAFT PIERS ............................................................................................................... 15 Allowable Uplift Resistance .................................................................................................................. 15

PIER SPACING .............................................................................................................................................. 15

LATERAL RESISTANCE .................................................................................................................................. 16


TABLE OF CONTENTS

ii

GRADE BEAMS ............................................................................................................................................. 17

FLOOR SLABS FOR PIER SUPPORTED STRUCTURES ................................................................................... 17

LATERAL EARTH PRESSURES ....................................................................................................................... 17 Drainage ................................................................................................................................................ 18 Waterproofing ...................................................................................................................................... 18 Backfill Compaction .............................................................................................................................. 19

FOUNDATION CONSTRUCTION CONSIDERATIONS ................................................................................. 19

SITE DRAINAGE ............................................................................................................................................ 19

SITE PREPARATION ...................................................................................................................................... 19

SELECT FILL AND ONSITE SOILS ................................................................................................................... 20

SHALLOW FOUNDATION EXCAVATIONS .................................................................................................... 21

DRILLED PIERS.............................................................................................................................................. 21 Reinforcement and Concrete Placement ............................................................................................ 21 Temporary Casing ................................................................................................................................. 22

CRAWL SPACE CONSIDERATIONS ............................................................................................................... 22 Ventilation ............................................................................................................................................ 22 Below Slab Utilities ............................................................................................................................... 22 Drainage ................................................................................................................................................ 22 Carton Forms ........................................................................................................................................ 22

TEMPORARY EXCAVATION SLOPING AND BENCHING ............................................................................... 23

EXCAVATION EQUIPMENT .......................................................................................................................... 23

PERMANENT SLOPES ................................................................................................................................... 24

UTILITIES ...................................................................................................................................................... 24

PAVEMENT RECOMMENDATIONS ......................................................................................................... 24

SUBGRADE CONDITIONS ............................................................................................................................. 24

DESIGN INFORMATION ............................................................................................................................... 25

PAVEMENT DESIGN PARAMETERS – HOT MIX ASPHALT PAVEMENTS ..................................................... 25 Performance Period ............................................................................................................................. 25 Roadbed Soil Resilient Modulus .......................................................................................................... 25 Serviceability Indices ............................................................................................................................ 25 Overall Standard Deviation .................................................................................................................. 25 Reliability, % .......................................................................................................................................... 26 Design Traffic 18-kip ESAL .................................................................................................................... 26 Design Structural Number .................................................................................................................... 26

RECOMMENDED PAVEMENT SECTIONS - HOT MIX ASPHALT PAVEMENT ............................................... 26

PAVEMENT DESIGN PARAMETERS – PORTLAND CEMENT CONCRETE PAVEMENTS ............................... 26 Performance Period ............................................................................................................................. 27 28-day Concrete Modulus of Rupture, Mr ........................................................................................... 27 28-day Concrete Elastic Modulus ........................................................................................................ 27


TABLE OF CONTENTS

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Effective Modulus of Subbase/Subgrade Reaction: k-value ............................................................... 27 Serviceability Indices ............................................................................................................................ 27 Load Transfer Coefficient ..................................................................................................................... 27 Drainage Coefficient ............................................................................................................................. 28 Overall Standard Deviation .................................................................................................................. 28 Reliability, % .......................................................................................................................................... 28 Design Traffic 18-kip ESAL .................................................................................................................... 28

RECOMMENDED PAVEMENT SECTIONS - RIGID PAVEMENT .................................................................... 28

PAVEMENT CONSTRUCTION CONSIDERATIONS ..................................................................................... 29

SUBGRADE PREPARATION .......................................................................................................................... 29

DRAINAGE CONSIDERATIONS ..................................................................................................................... 29

ON-SITE CLAY FILL ........................................................................................................................................ 30

TREATMENT OF SUBGRADE ........................................................................................................................ 30

FLEXIBLE BASE COURSE ............................................................................................................................... 30

ASPHALTIC CONCRETE SURFACE COURSE .................................................................................................. 30

PORTLAND CEMENT CONCRETE ................................................................................................................. 31

CONSTRUCTION RELATED SERVICES ...................................................................................................... 31

CONSTRUCTION MATERIALS TESTING AND OBSERVATION SERVICES ...................................................... 31

BUDGETING FOR CONSTRUCTION TESTING ............................................................................................... 31

ATTACHMENTS The following figures are attached and complete this report: Boring Location Map .......................................................................................................................... Figure 1 Logs of Borings .......................................................................................................................... Figures 2 to 9 Key to Terms and Symbols ............................................................................................................... Figure 10 Results of Soil Analyses .................................................................................................................... Figure 11 Consolidation Curves ....................................................................................................................... Figure 12 Dynamic Cone Penetration Tests .................................................................................................... Figure 13 Appendix A – Supplemental Recommendations and Considerations Important Information About Your Geotechnical Engineering Report


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INTRODUCTION RABA KISTNER Consultants Inc. (RKCI) has completed the subsurface exploration for the proposed Intermediate Pump Station No. 1 located in Bastrop County, Texas, as illustrated on Figure 1. This report briefly describes the procedures utilized during this study and presents our findings along with our recommendations for foundation design and construction considerations, as well as for pavement design and construction guidelines.

PROJECT DESCRIPTION The facilities being considered in this study include new structures for the Vista Ridge – Regional Supply Project’s Intermediate Pump Station No. 1 (IPS No. 1), located approximately 1.3 miles east of the intersection of TX-95 and US-290 on parcel 30121 in Bastrop County, Texas. The facilities for the IPS No. 1 will include the following:

• One 4 million gallon grade-supported tank • A booster pump pad • A transformer pad • Two pre-cast concrete chemical/electrical building • Access road with concrete/asphalt pavement

Our understanding of the existing topography, tank dimensions, and capacities are based on the proposed site layout provided to us titled Single Feed – Dual Gas Main Crossing, Intermediate Pump Station No. 1 Revision 1. This drawing includes proposed finished floor elevations of 572 ft and 565 ft for the tank and booster pump pad, respectively. The following table presents our estimates for the proposed 5 million gallon tank based on the above-referenced drawings and the project information provided to us.

Tank Parameters

Capacity of

Proposed Storage

Tank (gal)

Tank Material

Inside Diameter

of Proposed Storage

Tank (ft)

Proposed FFE (ft)

Design Side

Water depth

(ft)

Estimated Contact Pressure

(ksf) Allowable

Total Settlement

(in.)

Maximum Tolerable

Differential Settlement

Between Tank Perimeter and

Tank Center (in.)

Slab Perimeter 4 in. Slab

6 in. Slab

4,000,000 Precast,

Prestressed Concrete

144 572 33 2.1 3.0 6* 3.9* 2.6*

*Based on section A.3.2 of the American Concrete Institute (ACI) document entitled “Design and Construction of Circular Wire- and Strand-Wrapped Prestressed Concrete Structures” (ACI 372R).

LIMITATIONS This engineering report has been prepared in accordance with accepted Geotechnical Engineering practices in the region of south/central Texas and for the use of VRRSP Consultants, LLC (CLIENT) and its representatives for design purposes. This report may not contain sufficient information for purposes of other parties or other uses. This report is not intended for use in determining construction means and methods. The recommendations submitted in this report are based on the data obtained from 8 borings drilled at this site, our understanding of the project information provided to us, and the assumption that site


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grading will result in only minor changes in the existing topography. If the project information described in this report is incorrect, is altered, or if new information is available, we should be retained to review and modify our recommendations. This report may not reflect the actual variations of the subsurface conditions across the site. The nature and extent of variations across the site may not become evident until construction commences. The construction process itself may also alter subsurface conditions. If variations appear evident at the time of construction, it may be necessary to reevaluate our recommendations after performing on-site observations and tests to establish the engineering impact of the variations. The scope of our Geotechnical Engineering Study does not include an environmental assessment of the air, soil, rock, or water conditions either on or adjacent to the site. Although Photoionization Detector (PID) readings are provided herein, no environmental opinions are presented in this report. If final grade elevations are significantly different from existing grades (more than plus or minus 1 ft), our office should be informed about these changes. If needed and/or if desired, we will reexamine our analyses and make supplemental recommendations.

BORINGS AND LABORATORY TESTS Subsurface conditions at the site were evaluated by 8 borings drilled at the locations shown on the Boring Location Map, Figure 1. These locations are approximate and distances were measured using a recreational-grade, hand-held, GPS locator; tape; angles; pacing; etc. Ground surface elevations were estimated from the topography depicted on the above-referenced drawing provided by VRRSP Consultants, LLC. The estimated ground surface elevation at each of the boring locations is listed in the table below as well as the approximate bottom elevation of each boring.

Boring Summary

Structure Boring No. Approximate Ground

Surface Elevation (ft, MSL)

Approximate Boring Bottom Elevation

(ft, MSL)

Transformer Pad TP-30121-01 568* 543

Electrical Building CE-30121-01 566 541

Chemical Building CE-30121-02 566 541

Booster Pump BP-30121-01 565* 540

Tank

T-30121-01 568* 518

T-30121-02 567* 537

T-30121-03 567* 537

T-30121-04 568* 538 *Elevations estimated using Google Earth. The borings were drilled using a truck-mounted drilling rig, and during drilling operations, Split-Spoon (with Standard Penetration Test), Shelby Tube, and Grab Samples were collected. Each sample was visually classified in the laboratory by a member of our geotechnical engineering staff. The geotechnical engineering properties of the strata were evaluated by natural moisture content, Atterberg limits, percent passing a No. 200 sieve, unconfined compressive strength, and consolidation tests. In addition, analytical testing was performed on select samples to evaluate the soil corrosivity. The results of laboratory tests are presented in graphical or numerical form on the boring logs illustrated on Figures 2 through 9. A key to classification terms and symbols used on the logs is presented on Figure 10. The results of the laboratory and field testing are also tabulated on Figure 11 for ease of reference. The consolidation curves are presented on Figure 12. Along the proposed


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roadway, three Dynamic Cone Penetration tests (DCP) were performed to evaluate the soil stiffness for the pavement design. The results of the DCP testing are presented on Figure 13 of this report. Standard Penetration Test results are noted as “blows per ft” on the boring logs and Figure 11, where “blows per ft” refers to the number of blows by a falling hammer required for 1 ft of penetration into the soil/weak rock (N-value). Where hard or dense materials were encountered, the tests were terminated at 50 blows even if one foot of penetration had not been achieved. When all 50 blows fall within the first 6 in. (seating blows), refusal “ref” for 6 in. or less will be noted on the boring logs and on Figure 11. Unless noted on the boring logs, the lines designating the changes between various strata represent approximate boundaries. The transition between materials may be gradual or may occur between recovered samples. The stratification given on the boring logs, or described herein, is for use by RKCI in its analyses and should not be used as the basis of design or construction cost estimates without realizing that there can be variation from that shown or described. The boring logs and related information depict subsurface conditions only at the specific locations and times where sampling was conducted. The passage of time may result in changes in conditions, interpreted to exist, at or between the locations where sampling was conducted. CORROSIVITY TESTING As requested by ELK Engineering Associates, Inc., the corrosivity characteristics of the soils were evaluated using pH, resistivity, sulfate content, and chloride content tests. These tests were performed on a selected soil specimen obtained from the subsurface soils within the tank footprint. Results are summarized in the following table.

Corrosivity Testing Summary

Boring Depth (ft) Resistivity (Ohm-cm)

Sulfate Content (ppm) pH

Chloride Content (ppm)

T-30121-01 8 to 12 6,860 680 9.3 568 Ductile Iron Pipe Based on the results of the resistivity, pH and Chlorides tests, the soil sample collected from Boring T-30121-01 is corrosive to buried cast iron pipe. Hence, protecting buried cast iron pipes, such as encasing with polyethylene film, should be considered at this site. Cement Type The potential for concrete exposure to sulfates was evaluated based on Table 2-2 in Design and Control of Concrete Mixtures, 14th Edition, issued by the Portland Cement Association (PCA). The onsite soils have a negligible sulfate content based on the results of the current sulfate test. Consequently, use of any type of concrete for below-grade construction in contact with the natural soil can be considered. However, we recommend additional laboratory testing be performed on the select fill and in-situ soils to determine and verify the concentration of soluble sulfates. GEOPHYSICAL TESTING FOR DYNAMIC SOIL PROPERTIES The effort for this is ongoing and the findings will be submitted in a supplemental letter presented in Appendix A.


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PHOTOIONIZATION DETECTOR AND CUMBUSTIBLE GAS INDICATOR SCREENING RESULTS The results of Photoionization Detector (PID) and Combustible Gas Indicator (CGI) screening are presented in the following table. The information provided herein is for the use of the design team. Interpretation or recommendations are beyond our scope of service.

PID and CGI Summary

Approximate Sample

Depth (ft)

Boring T-30121-01

Boring T-30121-02

Boring

T-30121-03 Boring

T-30121-04 PID VOC

(ppm)

LEL (%)

PID VOC

(ppm)

LEL (%)

PID VOC

(ppm)

LEL (%)

PID VOC

(ppm)

LEL (%)

1.5 4 ND 2 ND 1 ND 10 ND 3.5 2 ND 6 ND 1 ND 4 ND 5.5 4 ND 7 ND 1 ND 1 ND 7.5 4 ND 3 ND ND ND 4 ND 9.5 5 ND 6 ND 2 ND ND ND

11.5 11 ND - - - - - -

14.5 3 ND 1 ND 2 ND 1 ND 19.5 10 ND 2 ND 3 ND 1 ND 24.5 3 ND 1 ND 1 ND 1 ND 29.5 5 ND ND ND ND ND ND ND

34.5 2 ND - - - - - -

39.5 2 ND - - - - - -

44.5 1 ND - - - - - -

49.5 ND ND - - - - - -

ND - Not Detected “-“ - Not explored/sampled


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PID and CGI Summary (Continued)

Approximate Sample

Depth (ft)

Boring TP-30121-01

Boring CE-30121-01

Boring

CE-30121-02

Boring BP-30121-01

PID VOC

(ppm)

LEL (%)

PID VOC

(ppm)

LEL (%)

PID VOC

(ppm)

LEL (%)

PID VOC

(ppm)

LEL (%)

1 1 ND 2 ND 1 ND 5 ND

3.5 1 ND ND ND 4 ND 1 ND 5.5 1 ND 2 ND 1 ND 4 ND 7.5 3 ND 1 ND ND ND 2 ND 9.5 ND ND ND ND 1 ND 1 ND

14.5 1 ND 1 ND 1 ND 2 ND 19.5 ND ND 1 ND 1 ND ND ND 24.5 ND ND ND ND ND ND ND ND

ND - Not Detected “-“ - Not explored/sampled

GENERAL SITE CONDITIONS

SITE DESCRIPTION The project site is a tract of undeveloped land located approximately 1.3 miles east of the intersection of TX-95 and US-290 on the parcel identified as No. 30121 in Bastrop County, Texas. The site is primarily covered by grass. Ponds exist on the property, north of the IPS No. 1 site. The topography is relatively level with the highest elevation in the southeastern portion of the site, and slopes downward to the northwest with vertical relief of about 5 ft, as estimated by the publically available computer program Google Earth. Surface drainage is visually estimated to range from poor to fair. GEOLOGY A review of the Geologic Atlas of Texas, San Antonio Sheet, indicates that this site is naturally underlain with the soils/rocks of the Wilcox Group, which is composed of mudstone with varying amounts of sandstone and lignite. The Wilcox Group may weather to yellowish-brown clay, sandy clay, and sands. A key geotechnical engineering concern for development supported on this formation is expansive, soil-related movements. SEISMIC COEFFICIENTS The stratigraphy at this site consists of fine-grained soils with relatively thin sandy seams and based on our experience in the area, underlain by mudstone and/or sandstone bedrock. These strata are not considered susceptible to liquefaction during a seismic event. Based upon a review of Section 11.4.1 Earthquake Loads – Site Ground Motion of the 2010 Edition of ASCE 7, the following information has been summarized for seismic considerations associated with this site.

• Site Class Definition (Table 20.3-1): Class C. Based on the soil borings conducted for this investigation, the upper 100 feet of soil may be characterized as very dense soil and soft rock.


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• Risk-Targeted Maximum Considered Earthquake Ground Motion for a 0.2 sec Spectral Response Acceleration (Figure 22-1): Ss = 0.067g. Note that the value taken from Figure 22-1 is based on Site Class B and are adjusted per 11.6-1.

• Risk-Targeted Maximum Considered Earthquake Ground Motion for a 1 sec Spectral Response Acceleration (Figure 22-2): S1 = 0.035g. Note that the value taken from Figure 22-2 is based on Site Class B and are adjusted per 1613.5.3

• Values of Site Coefficient (Table 11.4-1): Fa = 1.2 • Values of Site Coefficient (Table 11.4-2): Fv = 1.7

The Maximum Considered Earthquake Spectral Response Accelerations are as follows:

• 0.2 sec, adjusted based on equation 11.4-1: Sms = 0.081g • 1 sec, adjusted based on equation 11.4-2: Sm1 = 0.060g

The Design Spectral Response Acceleration Parameters are as follows:

• 0.2 sec, based on equation 11.4-3: SDS = 0.054g • 1 sec, based on equation 11.4-4: SD1 = 0.040g

Based on Section 11.4.5 the Design Spectral Response Spectrum for the Mapped Long-Period Transition Period (Figure 22-12), TL = 12 Sec. The Risk Coefficients using Site-Specific Ground Motion Procedures for Seismic Design on Section 21.2.1.1-Method 1 are as follows:

• 0.2 sec, based on Figure 22-17: CRS = 0.894 • 1 sec, based on Figure 22-18: CR1 = 0.868

Based on the parameters listed above, Tables 11.6-1 and 11.6-2, and calculations performed using the United States Geological Survey (USGS) website, the Seismic Design Category for both short period and 1 second response accelerations is A. As part of the assumptions required to complete the calculations, a Risk Category of “I or II or III” was selected. STRATIGRAPHY Each stratum has been designated by grouping soils that possess similar physical and engineering characteristics. The boring logs should be consulted for more specific stratigraphic information. The lines designating the interfaces between strata on the boring logs represent approximate boundaries. Transitions between strata may be gradual. In general, the stratigraphy consists of stiff to hard brown clay to depths of 2 to 4 feet (Stratum I) overlying stiff to hard tan and gray clay (Stratum II), which in turn overlies very stiff to hard dark gray clay (Stratum III). A relatively thin layer of tan clayey sand was encountered from 4 ft to 8 ft in Boring TP-30121-01. GROUNDWATER Groundwater was not observed in the borings either during or immediately upon completion of the drilling operations. All borings remained dry during the field exploration phase. However, it is possible for groundwater to exist beneath this site at shallow depths (perched conditions), especially in the sand layer encountered in Boring TP-30121-01, on a transient basis. Groundwater levels may not have stabilized prior to backfilling, which is common in less permeable cohesive soil. Consequently, the lack of groundwater level observations in the borings may not represent present or future groundwater levels. Groundwater levels may vary significantly over time due to the effects of seasonal variation in


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precipitation, surface water run-off, the construction process/improvements itself, or other factors not evident at the time of exploration.

EXPANSIVE SOIL RELATED MOVEMENTS SITE GRADING Site grading plans can result in changes in almost all aspects of foundation recommendations. If site grading plans differ from those discussed in this report by more than plus or minus 1 ft, RKCI must be retained to review the site grading plans prior to bidding the project for construction. This will enable RKCI to provide input for any changes in our original recommendations that may be required as a result of site grading operations or other considerations. EXPANSIVE SOIL-RELATED MOVEMENTS The anticipated ground movements due to swelling of the underlying soils at the site were estimated for slab-on-grade construction using the empirical procedure, Texas Department of Transportation (TxDOT) Tex-124-E, Method for Determining the Potential Vertical Rise (PVR). PVR values ranging from 3-1/4 to 4-1/4 in. were estimated for the stratigraphic conditions encountered in our borings for the proposed equipment pad areas (Booster Pump, Chemical and Electrical Buildings, and Transformer Pad). A surcharge load of 1 psi (concrete slab and sand cushion), an active zone of 15 ft, and dry moisture conditions were assumed in estimating the above PVR values. It should be noted that the estimated PVR value within the proposed tank area is reduced to approximately 1 in. or less when the surcharge loading from the tank and water are considered. A PVR value of approximately 3-1/4 in. is estimated for the empty tank condition. The overexcavation and select fill replacement recommendations are presented in the following section titled Facility Pad PVR Reduction Options. The TxDOT method of estimating expansive soil-related movements is considered an acceptable method for this project, and is based on empirical correlations utilizing the measured plasticity indices and assuming typical seasonal fluctuations in moisture content. It should also be noted that actual movements can exceed the calculated PVR values due to isolated changes in moisture content (such as due to leaks, landscape watering....) or if water seeps into the soils to greater depths than the assumed active zone depth due to deep trenching or excavations. Facility Pad PVR Reduction Options We understand that site grading plans are still being developed. Facility pad PVR reduction options or some combination thereof may be considered by the Team to reduce the differential expansive soil-related movements to approximately 1 inch:

(a) overexcavation and select fill replacement, (b) surcharge addition, (c) overexcavation/surcharge addition, and (d) chemical treatment.

If site grading plans include raising the existing ground surface, the added surcharge load will assist in reducing the expansive soil-related movements. We estimate the PVR values will be reduced by about 1/4 in. for each 1 ft of granular select fill placed above the existing ground surface as indicated in the following tables. Estimating that the structures will be constructed near the existing ground surface, to reduce expansive soil-related movements in at-grade construction, a portion of the upper soils in the Storage Tank, Booster Pump, Chemical and Electrical Buildings, and Transformer Pad areas can be removed by overexcavating and backfilling with a suitable select fill material.


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As provided in the following, PVR values have been estimated for overexcavation and select fill replacement to various depths below the existing ground surface and are summarized in the tables below. Recommendations for the selection and placement of select backfill materials are addressed in a subsequent section of this report. Alternatively, chemical treatment may be considered as an option to potentially reduce soil related movements.

Tank Foundation

Empty Tank

Elevation of Overexcavation and Select Fill Replacement

(ft)

Estimated PVR with Select Fill

(in.)

568* 3-1/4

566 2-1/2

564 1-1/2

563 1-1/4

562 1 * Approximate existing ground surface elevation at the time of our study.

Full Tank


(ft)


(in.)

568* 1 or less * Approximate existing ground surface elevation at the time of our study,

overexcavation is not required.

Booster Pump Pad


(ft)


(in.)

565* 3-1/4

563 2-1/2

561 1-3/4

560 1-1/2

559 1-1/4



9

Electrical Building


(ft)


(in.)

566* 4-1/2

562 2-1/4

561 1-3/4

560 1-1/2

558 1-1/4


Chemical Building


(ft)


(in.)

566* 4-1/4

562 2

559 1-3/4

556 1-1/2

555 1-1/4


Transformer Pad


(ft)

Estimated PVR with Aggregate Select Fill

(in.)

568* 4-1/4

564 2

561 1-3/4

559 1-1/2

558 1-1/4


Chemical Treatment Another option that may be considered to reduce potential vertical

movements for the Booster Pump, Chemical and Electrical Buildings, and Transformer Pad areas is chemical treatment of the natural expansive subgrade soils. Proprietary potassium-based, aqueous solutions have been used successfully on several projects similar to the one proposed. Tests conducted by RKCI on soil samples obtained from project sites after chemical treatment have demonstrated favorable reductions in swell potential of the treated clays. Based on our experience this chemical


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treatment process/technique provides an additional option for managing highly plastic, expansive clay soils.

Since the chemical injection spacing and quantities can be varied to achieve different swell reduction results, no specific application recommendations can be provided. These factors impact not only the swell reduction but also the cost of the treatment process. If this method is to be considered at this site, the Owner should arrange a meeting as early as possible with personnel from RKCI, the chemical treatment contractor, the structural engineer, architect, and the Owner’s representatives. The purpose of the meeting would be to establish the required depth of treatment, feasible reductions in post-injection swell potential, the required application process, and acceptance criteria. Drainage Considerations When overexcavation and select fill replacement is selected as a method to reduce the potential for expansive soil-related movements at any site, considerations of surface and subsurface drainage may be crucial to construction and adequate foundation performance of the soil-supported structures. Filling an excavation in relatively impervious plastic clays with relatively pervious select fill material creates a “bathtub” beneath the structure, which can result in ponding or trapped water within the fill unless good surface and subsurface drainage is provided. Water entering the fill surface during construction or entering the fill exposed beyond the structure and tank lines after construction may create problems with fill moisture control during compaction and increased access for moisture to the underlying expansive clays both during and after construction. Several surface and subsurface drainage design features and construction precautions can be used to limit problems associated with fill moisture. These features and precautions may include but are not limited to the following:

• Installing berms or swales on the uphill side of the construction area to divert surface runoff away from the excavation/fill area during construction;

• Sloping of the top of the subgrade with a minimum downward slope of 1.5 percent out to the base of a dewatering trench located beyond the structures and tank perimeter;

• Sloping the surface of the fill during construction to promote runoff of rain water to drainage features until the final lift is placed;

• Sloping of a final, well maintained, impervious clay or pavement surface (downward away from the building and tank) over the select fill material and any perimeter drain extending beyond the building lines, with a minimum gradient of 6 in. in 5 ft;

• Constructing final surface drainage patterns to prevent ponding and limit surface water infiltration at and around the building and tank perimeter;

• Locating the water-bearing utilities, roof drainage outlets and other storm water features outside of the select fill and perimeter drain boundaries; and

• Raising the elevation of the ground level floor slab. Details relative to the extent and implementation of these considerations must be evaluated on a project-specific basis by all members of the project design team. Many variables that influence fill drainage considerations may depend on factors that are not fully developed in the early stages of design. For this reason, drainage of the fill should be given consideration at the earliest possible stages of the project.

FOUNDATION RECOMMENDATIONS Site grading plans and final foundation loading information have not been provided at this time. This information can result in changes in almost all aspects of our recommendations presented herein. We recommend that RKCI and the Design Team continue to work together as information becomes available. As subsequent recommendations and considerations develop during the course of the project, VRRSP Consultants should add the supplemental letters/reports to Appendix A as provided herein.


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STORAGE TANK FOUNDATION We assume that the proposed storage tank will be founded on a 4 in or 6 in thick concrete slab-on-grade that is thickened along the tank perimeter. The finished floor elevation (FFE) provided is 572 ft, and the current ground elevation is approximately 568 ft. From this information it is estimated that approximately 4 ft of fill will be required to achieve final grades. Loads from the tank will influence the underlying soil to a greater depth than conventional shallow foundations. Consequently, the tank foundation is expected to experience more settlement due to the depth of soil influenced. On the basis of our settlement calculations, we estimate total settlement to be on the order of 6 in. Differential settlement is estimated to be 3 in. between the center and edge of the tank foundation. To reduce the expansive soil related movements for an empty tank, an approximately 6 ft deep overexcavation and replacement with compacted crushed rock may be required. With this approach, the total and differential settlement is reduced to approximately 5 and 2-1/2 inches, respectively. The tank manufacturer should be consulted for acceptable total and differential settlements. The tank perimeter foundation may be designed for a net allowable bearing pressure of 3,500 psf (using a factor of safety of 3), provided the footings bear on compacted select fill as recommended in the Select Fill section of this report. In general, the subgrade modulus is the relationship between foundation settlement and bearing pressure. Using the allowable bearing pressures provided herein (3,500 psf), foundations proportioned and constructed as recommended may have a differential settlements of approximately 2-1/2 to 3 in. Hence, an average subgrade modulus of approximately 9 pci may be used. The excavated area should be prepared in accordance with the Site Preparation section of this report. Upon completion of site preparation, the select fill should be placed in the tank foundation area in accordance with the Select Fill section of this report. If granular select fill and placement is performed as discussed in the section titled Select Fill, then a geotextile fabric will not be required between the native soils and the granular select fill. Estimated values of settlement contained in this report are based on our experience with projects of a similar nature and consolidation tests. RKCI should be contacted if the final elevation of the tank foundation is altered from what has been estimated. Tank Pre-Loading Recommendations On the basis that the tank may be underlain by a 6 ft thick compacted crushed rock mat and our settlement calculations, we estimate total and differential settlement will be approximately 5 and 2-1/2 inches, respectively. The tank manufacturer should be consulted for acceptable total and differential settlements. To reduce the potential for differential movement between the tank and service lines, consideration may be given to pre-loading the tank. Tank pre-loading generally consists of filling the tank with water, after construction, under controlled conditions. After the pre-load is completed the pipe connections are made in order to reduce the amount of displacement which may be experienced between the pipe and tank connections. The following general guidelines may be used to establish the pre-loading program:

Survey Control A series of reference points are established around the tank shell and movements monitored during pre-loading. We suggest at least six settlement points be established equally spaced around the perimeter of the tank. Settlement observations of these points should be obtained prior to, during, and after pre-loading. Readings should be referenced to a permanent benchmark well away from the zone of influence, at least two tank diameters. Loading We suggest that water for the pre-loading be added in 5-ft stages to reach full tank height. Each water level stage should be maintained until settlement readings show either no


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movement or until the settlement rate is smaller than a predetermined range (RKCI can estimate once additional information is provided). Data Evaluation Settlement observations should be reviewed as the pre-loading proceeds to assess differential settlement, local slope, tank tilt, and out-of-plane distortion, and corrective action should be taken, if necessary. Settlement observations should be obtained frequently enough to develop the data necessary to assess tank performance and should be reviewed by the Tank Manufacturer. The calculated range (shaded red) for the consolidation rate of the underlying natural soil below the tank center is estimated in the following figure. Please note that this plot assumes an instantaneous loading condition and is only plotted up to 1 year. The time required to achieve approximately 1 inch of residual consolidation is estimated to be approximately 2 to 7 years.

FACILITY FOUNDATION OPTIONS The following recommendations are based on the data obtained from our field and laboratory studies, and our engineering design analyses for the Booster Pump, Chemical and Electrical Buildings, and Transformer Pad. The structures may be founded on a shallow foundation system or a stiffened engineered beam slab foundation provided the selected foundation type can be designed to withstand the anticipated soil-related movements (see Expansive Soil-Related Movements) without impairing either the structural or the operational performance of the structure. For structures that have high performance criteria or which are movement sensitive in nature may be supported on deep foundations such as drilled-and-underreamed piers and drilled, straight-shaft piers. The Team may select either one of these foundation systems depending on the performance criteria established for the structures. Special attention must be given to designing conventional shallow foundations immediately adjacent to structures supported on drilled piers, if any. Construction joints should be provided between structures supported on conventional shallow foundations and pier-supported structures to accommodate potential differential movement. In general, the allowable values given herein for shallow and deep foundations can be increased by 33 percent for seismic, wind or other transitory loads.


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SHALLOW FOUNDATIONS For a shallow foundation system to be considered, we recommend that the building pad subgrade be modified, overexcavated and replaced, or some combination thereof as discussed previously provided the selected foundation type can be designed to withstand the anticipated soil-related movements (i.e. expansive and settlement related movements). The floor slab may be constructed on the select structural fill building pad with isolated spread footing to support the interior column loads. The recommended design criteria for the foundation system are provided in the following sections. Net Allowable Bearing Capacity Foundations founded on compacted, select fill may be proportioned using the design parameters tabulated below.

Shallow Foundation Design Parameters

Minimum depth below final grade* 18 in.

Minimum beam/strip footing width 12 in.

Minimum widened beam or spread footing width 18 in.

Maximum net allowable bearing pressure for grade beams/strip footings 3,000 psf

Maximum net allowable bearing pressure for spread footings 3,500 psf * The average frost depth for this area in Texas is 5 inches. The above presented maximum net allowable bearing pressures will provide a calculated factor of safety of about 3 provided that fill is selected and placed as recommended in the Select Fill section of this report. In areas where select fill placement will be performed, we estimate total settlement to be on the order of 1 percent of the depth of select fill material provided the material is placed and compacted as discussed herein. Differential settlement is estimated to be approximately 1/2 of the total settlement. Uplift Resistance Resistance to vertical force (uplift) is provided by the weight of the concrete footing plus the weight of the soil directly above the footing. For this site, it is recommended that the ultimate uplift resistance be based on total unit weights for soil and concrete of 100 pcf and 150 pcf, respectively. The calculated ultimate uplift resistance should be reduced by a factor of safety of 1.2 to calculate the allowable uplift resistance. Lateral Resistance Horizontal loads acting on spread footings will be resisted by passive earth pressure acting on one side of the footing and by base adhesion for footings in cohesive soils. Resistance to sliding for foundations bearing on natural/compacted soil or granular select fill should be calculated utilizing an ultimate coefficient of friction of 0.30 or 0.35, respectively. The allowable resistance for these foundations should be limited to 750 psf. An equivalent fluid pressure of 250 pcf should be utilized to determine the ultimate passive resistance, if required. Area Flatwork and Floor Slabs It should be noted that ground-supported flatwork such as pavements, as well as buried piping, will be subject to the same magnitude of potential soil-related movements as discussed previously (see Expansive Soil-Related Movement section). Thus, where these types of elements abut rigid foundations or isolated structures, differential movements should be anticipated. As a minimum, we recommend that flexible joints or connections be provided where such elements abut the main structure to allow


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for differential movement at these locations. For floor slabs and flatwork supported by natural soil, a subgrade modulus (k-value) of 150 pci may be utilized for slabs constructed for this project. The subgrade modulus may be increased to 250 pci if the floor slabs and flatwork is underlain by 2 feet of compacted aggregate select fill. If differential movements between the soil-supported slab and the structure are objectionable, soil-supported floor slabs could be dowelled to the perimeter grade beams or strip footings. Dowelled slabs that are subjected to heaving will typically crack and develop a plastic hinge along a line which will be approximately 5 to 10 ft inside and parallel to the grade beams or strip footing. Slabs cast independent of the grade beams, interior columns and partitions should experience minimum cracking, but may create difficulties at critical entry points such as doors and may impact interior partitions that are secured to exterior walls. Where potential moisture penetrating from underneath the slab is objectionable, we recommend that a vapor barrier (6-mil or thicker) comprised of polyethylene or polyvinylchloride (PVC) sheeting be placed between the supporting soils and the concrete floor slab. DEEP FOUNDATIONS Drilled-and-underreamed piers and drilled, straight-shaft piers may be considered for movement sensitive structures. Regardless of the system selected, deep foundations must be designed to resist potential uplift forces from the surrounding expansive soils. Pier Shaft Potential Uplift Forces The pier shafts will be subject to potential uplift forces if the surrounding expansive soils within the active zone are subjected to alternate drying and wetting conditions. The maximum potential uplift force acting on the shaft may be estimated by:

Fu = 71*D where:

Fu = uplift force in kips; and D = diameter of the shaft in feet.

DRILLED-AND-UNDERREAMED PIERS Drilled-and-underreamed piers bearing in the underlying hard clays may be considered to support the structure. We recommend that piers extend to a minimum depth of 30 ft below the ground surface existing at the time of our study, or 30 ft below the final ground surface, whichever is greater. The piers should be designed as end-bearing units using a maximum allowable bearing pressure of 15 ksf. This bearing pressure was evaluated using a calculated factor of safety of at least 3 with respect to the design shear strength. The piers should be sized appropriately such that the pier depth does not exceed a depth of 50 ft below the ground surface existing at the time of our study. Allowable Uplift Resistance Resistance to uplift forces exerted on the drilled piers will be provided by the sustained axial compressive force (dead load) plus the allowable uplift resistance provided by the soil. The resistance provided by the soil depends on the bearing capacity of the soils located above the pier underream (bell) and below the active zone. The allowable uplift resistance for underreamed piers founded at the depth recommended above may be estimated using:

Ru = 9*(B2 - D2)


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where:

Ru = uplift resistance in kips; B = diameter of the underream in feet; and D = diameter of the shaft in feet.

Due to the blocky/slicken-sided nature of the underlying clays, we recommend that the bell-to-shaft diameter ratio be a minimum of 2, and not exceed 2.5. Reinforcing steel will be required in each pier shaft to withstand a net force equal to the uplift force minus the sustained compressive load carried by the pier. We recommend that each pier be reinforced to withstand this net force or an amount equal to 1 percent of the cross-sectional area of the shaft, whichever is greater. DRILLED, STRAIGHT-SHAFT PIERS Drilled, straight-shaft piers may also be considered to support the proposed structures. Consequently, pier capacity could be equal to the summation of the following: (1) the end area of the pier multiplied by the allowable end-bearing pressure and (2) the wall area of the pier socket below the 15 ft active zone into the underlying hard clay surface area multiplied by the allowable side shear resistance. The piers should be sized appropriately such that the pier depth does not exceed a depth of 50 ft below the ground surface existing at the time of our study. Drilled, straight-shaft piers extending into the underling clays may be proportioned for a net allowable bearing pressure of 15 ksf. This bearing pressure was evaluated using a calculated factor of safety of at least 3. Straight-shaft piers may be designed using an allowable side shear resistance value of 1.5 ksf from below the 15 ft active zone to El 518 (limit of our exploration). The provided value is based on a factor of safety of 2 with respect to the design shear strength. Final shaft depths will be based on interpretation of conditions in the field at the time of construction. Due to the variable conditions at this site, RKCI must be present at the time of pier construction to verify the field conditions are similar to those assumed in the preparation of our recommendations. For bid purposes, the owner should anticipate that deeper piers will be required in some areas. Consequently, contractors bidding on the job should include unit costs for various depths of additional pier embedment. Allowable Uplift Resistance Resistance to uplift forces exerted on the drilled, straight-shaft piers will be provided by the sustained compressive axial force (dead load) plus the allowable uplift resistance provided by the soil. The resistance provided by the soil depends on the shear strength of the soils adjacent to the pier shaft and below the depth of the active zone. The allowable uplift resistance provided by the soils at this site may be estimated using 2/3 of the axial compressive side shear resistance for the portion of the shaft extending below a depth of 15 ft. Reinforcing steel will be required in each pier shaft to withstand a net force equal to the uplift force minus the sustained compressive load carried by that pier. We recommend that each pier be reinforced to withstand this net force or an amount equal to 1 percent of the cross-sectional area of the shaft, whichever is greater. PIER SPACING Where possible, we recommend that the piers be spaced at a center to center distance of at least three shaft diameters on-center for straight-shaft piers and three bell-diameters for underreamed piers. Such spacing will not require a reduction in the load carrying capacity of the individual piers. If design and/or construction restraints require that piers be spaced closer than the recommended three shaft or bell diameters, RKCI must re-evaluate the allowable bearing capacities presented above


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for the individual piers. Reductions in load carrying capacities may be required depending upon individual loading and spacing conditions. LATERAL RESISTANCE Resistance to lateral loads and the expected pier behavior under the applied loading conditions will depend not only on subsurface conditions, but also on loading conditions, the pier size, and the engineering properties of the pier. As this information is not yet available, analysis of pier behavior is not possible at this time. Once preliminary pier sizes, concrete strength, and reinforcement are known, piers should be analyzed to determine the resulting lateral deflection, maximum bending moment, and ultimate bending moment. This type of analysis is typically performed utilizing a computer analysis program and usually requires a trial and error procedure to appropriately size the piers and meet project tolerances. To assist the design engineer in this procedure, we are providing the following soil parameters for use in analysis. These parameters are in accordance with the input requirements of one of the more commonly used computer programs for laterally loaded piles, the LPile program. If a different program is used for analysis, different parameters and limitations may be required than what were assumed in selecting the parameters given below. Thus, if a program other than LPile is used, RKCI must be notified of the analysis method, so that we can review and revise our recommendations if required. We recommend that any depth of fill or any depth of disturbed or uncompacted material be neglected for analysis. The parameters for native, undisturbed material are presented in the tables below with corresponding elevations for each proposed structure. Additionally, the final depth/elevation of excavation should be considered when utilizing the parameters below.

Assumed Behavior for Analysis Depth (ft)* c (psf)

ks (pci)

ε50 γ' (pcf)

Soft Clay 0 to 5 500 30 0.020 63

Stiff Clay without free water 5 to 30 2,300 1,000 0.005 53

Stiff Clay without free water 30 to 50 5,000 2,000 0.004 58

*Estimated below the existing ground surface. Where: c = undrained cohesion ks = p-y modulus ε50 = strain factor γ’ = effective unit weight The values presented above for subgrade modulus and the strain at 50% are based on recommended values for the LPile program for the strength of materials encountered in our borings and are not necessarily based on laboratory test results. The parameters presented in the above table do not include factors of safety nor have they been factored. It should be noted that where piers are spaced closer than three shaft diameters center to center, a modification factor should be applied to the p-y curves to account for a group effect. We recommend the following p-Multipliers for the corresponding center to center pier spacing.

Spacing (in shaft diameters)

p-Multiplier

3 1.0

2 0.75

1 0.50


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GRADE BEAMS We recommend that the grade beams interconnecting the piers be structurally suspended due to the anticipated ground movements. A positive void space of at least 12 in., preferably more, should be provided between the soffits of grade beams and the underlying soils. FLOOR SLABS FOR PIER SUPPORTED STRUCTURES Two alternatives are available to construct the floor slab system for pier supported structures. The Owner may select the alternative best satisfying the required performance criteria. Where potential moisture penetrating from underneath the slab is objectionable, we recommend that a vapor barrier (6-mil or thicker) comprised of polyethylene or polyvinylchloride (PVC) sheeting be placed between the supporting soils and the concrete floor slab.

Alternative No. 1: Floor slabs which have high performance criteria or which are movement sensitive in nature should be structurally suspended because of the anticipated ground movements. A positive void space of at least 12 in., preferably more, should be provided between the slab and the underlying soils (see also Crawl Space Considerations). Areas containing critical entry/exit points, such as doorways, should consider using a suspended system to relieve those areas of heave stresses caused by expansive soils. Alternative No. 2: Floor slabs within the superstructure may be ground supported provided the anticipated movements discussed under the Expansive Soil-Related Movements section of this report will not impair the performance of the floor, frame, or roof systems. If differential movements between the slab and the structure are objectionable, soil-supported floor slabs could be dowelled to the perimeter grade beams. Dowelled slabs that are subjected to heaving will typically crack and develop a plastic hinge along a line which will be approximately 5 to 10 ft inside and parallel to the grade beams. Slabs cast independent of the grade beams, interior columns and partitions should experience minimum cracking, but may create difficulties at critical entry points such as doors and may impact interior partitions that are secured to exterior walls.

LATERAL EARTH PRESSURES The sections below provide design values for different types of backfill material as well as backfill compaction recommendations for below grade structures, if any. Equivalent fluid density values for computation of lateral soil pressures acting on below grade were evaluated for various types of backfill materials that may be placed behind the walls. These values, as well as corresponding lateral earth pressure coefficients and estimated unit weights, are presented below in preferential order for use as backfill materials.

Back Fill Type

Estimated Total Unit

Weight (pcf)

Active Condition At Rest Condition

Earth Pressure Coefficient, ka

Equivalent Fluid Density

(pcf) Earth Pressure Coefficient, ko


(pcf)

Washed Gravel 135 0.29 40 0.45 60

Crushed Limestone 145 0.24 35 0.38 55

Clean Sand 120 0.33 40 0.5 60

Pit Run Clayey Gravels or Sands 135 0.32 45 0.48 65


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Back Fill Type

Estimated Total Unit

Weight (pcf)

Active Condition At Rest Condition

Earth Pressure Coefficient, ka


(pcf) Earth Pressure Coefficient, ko


(pcf)

Inorganic Clays of Low to Medium Plasticity (Liquid Limit less than 40 percent)

120 0.40 50 0.55 65

The values tabulated above under “Active Conditions” pertain to flexible retaining walls free to tilt outward as a result of lateral earth pressures. For rigid, non-yielding walls the values under “At-Rest Conditions” should be used. The values presented above assume the surface of the backfill materials to be level. Sloping the surface of the backfill materials will increase the surcharge load acting on the structures. The above values also do not include the effect of surcharge loads such as construction equipment, vehicular loads, or future storage near the structures. Nor do the values account for possible hydrostatic pressures resulting from groundwater seepage entering and ponding within the backfill materials. However, these surcharge loads and groundwater pressures should be considered in designing any structures subjected to lateral earth pressures. The on-site clays exhibit significant shrink/swell characteristics and the use of these soils as backfill against the proposed retaining structures, if any, is not recommended. These soils generally provide higher design active earthen pressures, but may also exert additional active pressures associated with swelling. Drainage The use of drainage systems is a positive design step toward reducing the possibility of hydrostatic pressure acting against the retaining structures. Drainage may be provided by the use of a drain trench and pipe. The drain pipe should consist of a slotted, heavy duty, corrugated polyethylene pipe and should be installed and bedded according to the manufacturer’s recommendations. The drain trench should be filled with gravel (meeting the requirements of ASTM D 448 coarse concrete aggregate Size No. 57 or 67) and extend from the base of the structure to within 2 ft of the top of the structure. The bottom of the drain trench will provide an envelope of gravel around the pipe with minimum dimensions consistent with the pipe manufacturer’s recommendations. The gravel should be wrapped with a suitable geotextile fabric (such as Mirafi 140N or equivalent) to help minimize the intrusion of fine-grained soil particles into the drain system. The pipe should be sloped and equipped with clean-out access fittings consistent with state-of-the-practice plumbing procedures. As an alternative to a full-height gravel drain trench behind the proposed retaining structures, consideration may be given to utilizing a manufactured geosynthetic material for wall drainage. A number of products are available to control hydrostatic pressures acting on earth retaining structures, including Amerdrain (manufactured by American Wick Drain Corp.), Miradrain (manufactured by Mirafi, Inc.), Enkadrain (manufactured by American Enka Company), and Geotech Insulated Drainage Panel (manufactured by Geotech Systems Corp.). The geosynthetics are placed directly against the retaining structures and are hydraulically connected to the gravel envelope located at the base of the structures. Waterproofing Consideration may also be given to applying waterproofing coatings to any below grade walls. Waterproofing for capillary moisture is often accomplished by painting the wall exteriors with a bituminous material. For greater seepage protection, membrane waterproofing would be required. Based on our observations of groundwater conditions at this site, it appears that application of a bituminous material will provide adequate waterproofing for below grade walls, if any.


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Backfill Compaction Placement and compaction of backfill behind the walls will be critical, particularly at locations where backfill will support adjacent near-grade foundations and/or flatwork. If the backfill is not properly compacted in these areas, the adjacent foundations/flatwork can be subject to settlement. To reduce potential settlement of adjacent foundations/flatwork, the backfill materials should be placed and compacted as recommended in the Select Fill section of this report. Each lift or layer of the backfill should be tested during the backfilling operations to document the degree of compaction. Within at least a 5-ft zone of the walls, we recommend that compaction be accomplished using hand-guided compaction equipment capable of achieving the maximum density. Placing the fill in thinner lifts may be required to achieve the desired compaction.

FOUNDATION CONSTRUCTION CONSIDERATIONS SITE DRAINAGE Drainage is an important key to the successful performance of any foundation. Good surface drainage should be established prior to and maintained after construction to help prevent water from ponding within or adjacent to the foundation and to facilitate rapid drainage away from the foundations. Failure to provide positive drainage away from the structure can result in localized differential vertical movements in soil supported foundations. Current ordinances, in compliance with the Americans with Disabilities Act (ADA), may dictate maximum slopes for walks and drives around and into new foundations. These slope requirements can result in drainage problems for foundations supported on expansive soils. We recommend that, on all sides of the foundations, the maximum permissible slope be provided away from the foundation. Also to help control drainage in the vicinity of the structure, we recommend that roof/gutter downspouts, other storm water features, and/or landscaping irrigation systems, if any, not be located adjacent to the foundations. Where a select fill overbuild is provided outside of the foundation footprint, the surface should be sealed with an impermeable layer (pavement or clay cap) to reduce infiltration of both irrigation and surface waters. Careful consideration should also be given to the location of water bearing utilities, as well as to provisions for drainage in the event of leaks in water bearing utilities. All leaks should be immediately repaired. Other drainage and subsurface drainage issues are discussed in the Expansive Soil-Related Movements section of this report. SITE PREPARATION Foundation areas and all areas to support select fill should be stripped of all vegetation and organic topsoil. Furthermore, as discussed in a previous section of this report, we recommend that overexcavation and select fill replacement be utilized to reduce expansive soil-related movements. Exposed subgrades should be thoroughly proofrolled in order to locate any weak, compressible zones. A fully-loaded dump truck or a similar heavily-loaded piece of construction equipment should be used for planning purposes. Proofrolling operations should be observed by the Geotechnical Engineer or his representative to document subgrade condition and preparation. Weak or soft areas identified during proofrolling should be removed and replaced with suitable, compacted on-site clays, free of organics, oversized materials, and degradable or deleterious materials. Upon completion of the proofrolling operations and just prior to fill placement or slab construction, the exposed subgrade should be moisture conditioned by scarifying to a minimum depth of 6 in. and recompacted as discussed herein. The moisture content of the subgrade should be maintained within the


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range of optimum moisture content to 3 percentage points above optimum moisture content until permanently covered. SELECT FILL AND ONSITE SOILS Materials used as select fill for the tank pad, preferably should be crushed stone or gravel aggregate. In addition, approximately 2 feet of crushed stone or gravel aggregate should be used where slabs will require a modulus of subgrade reaction of 250 pci. Options for select fill materials that may be utilized at this site are provided below.

Imported Crushed Limestone Base – Imported crushed limestone base materials should be should be crushed stone or gravel aggregate. We recommend that materials specified for use as select fill meet the TxDOT 2014 Standard Specifications for Construction and Maintenance of Highways, Streets and Bridges, Item 247, Flexible Base, Type A or B, Grade 1-2. Treated Onsite Materials – Lime/cement/super slurry treatment of the onsite soils may be considered in reducing the soil plasticity index (TxDOT Item 260 for Lime and Item 275 for cement). A sufficient quantity of product should be mixed with the subgrade soils to reduce the soil-product mixture plasticity index to approximately 20 or less. We recommend that approximately 5 percent lime and 6 percent cement by dry unit weight be assumed for treatment (these values have been increased by 1 percent to accommodate the field loss during construction). If cement treatment is selected, the mellowing period may be reduced to 24 hours prior to placing subsequent lifts. The final lift shall be cured for a minimum of 48 hours prior to placement of building foundation. Alternatively super slurry treatment can be used to reduce the PI and increase the soil stiffness. However, this is a proprietary product and the supplier should be contacted to evaluate the appropriate dosage rate. For this process, the contractor should allow a minimum of 12 hours, preferably 24 hours, before placing subsequent lifts. We recommend that during site grading operations that additional laboratory testing be performed to determine the appropriate treatment dosage rate and concentration of soluble sulfates in the subgrade and imported soils. Chemical Treatment – Another option that may be considered to reduce potential vertical movements is conventional (mixing or injection) chemical treatment of the natural expansive subgrade soils. Proprietary potassium-based, aqueous solutions have been used successfully by Hayward Baker on several projects similar to the one proposed. Tests conducted by RKCI on soil samples obtained from project sites after chemical treatment have demonstrated favorable reductions in swell potential of the treated clays. Based on our experience this chemical treatment process/technique provides an additional option for managing highly plastic, expansive clay soils. This is a proprietary product and the supplier should be contacted to evaluate the appropriate dosage rate. If injection methods are used subsequent verification borings and additional injection attempts may be required to achieve the desired results. Granular Pit Run Materials – Granular pit run materials should consist of GC, SC & combination soils (clayey gravels), as classified according to the Unified Soil Classification System (USCS). Alternative select fill materials shall have a maximum liquid limit not exceeding 40, a plasticity index between 7 and 20, and a maximum particle size not exceeding 4 inch. In addition, if these materials are utilized, grain size analyses and Atterberg Limits must be performed during placement at a rate of one test each per 5,000 cubic yards of material due to the high degree of variability associated with pit-run materials.

Imported Low PI Materials – Low PI materials should consist of CL clays, as classified according to the Unified Soil Classification System (USCS). Alternative select fill materials shall have a maximum liquid limit not exceeding 40, a plasticity index between 7 and 20, and a maximum particle size not exceeding 4 inch. In addition, if these materials are utilized, grain size analyses and Atterberg


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Limits must be performed during placement at a rate of one test each per 5,000 cubic yards of material due to the high degree of variability associated with these materials.

In general, select fill and onsite material should be placed in loose lifts not exceeding 8 in. in thickness and compacted to at least 95 percent of maximum density as determined by TxDOT, Tex-113-E, Compaction Test (please see the exception for the fills placed below the tank in the following paragraph for special considerations on fill placement). The moisture content of the fill should be maintained within the range of 2 percentage points below to 2 percentage points above the optimum moisture content until final compaction for imported crushed limestone base or granular pit run materials. For low PI materials, the moisture content of the fill should be maintained within the range of optimum to plus 3 percentage points above the optimum moisture content until final compaction and until permanently covered. Fills to support the proposed tank should be placed in loose lifts not exceeding 8 in. in thickness and compacted to at least 95 percent of maximum density as determined by ASTM D 1557, Modified Compaction Test. Onsite potentially expansive clays (PI greater than 20) should not be used as select fill unless the clay is chemically treated with potassium-based, aqueous solutions to reduce the plasticity index. Alternatively, the onsite soil (untreated) may be used in areas where potential vertical movements will not adversely impact either the structural or operational tolerances for the individual foundations, slabs or walls for which this material is being considered. SHALLOW FOUNDATION EXCAVATIONS Shallow foundation excavations should be observed by the Geotechnical Engineer or his representative prior to placement of reinforcing steel and concrete. This is necessary to verify that the bearing soils at the bottom of the excavations are similar to those encountered in our borings and that excessive loose materials and water are not present in the excavations. If soft soils are encountered in the foundation excavations, they should be removed and replaced with a compacted non-expansive fill material or lean concrete up to the design foundation bearing elevations. DRILLED PIERS Each drilled pier excavation must be examined by an RKCI representative who is familiar with the geotechnical aspects of the soil stratigraphy, the structural configuration, foundation design details and assumptions, prior to placing concrete. This is to observe that:

• The shaft and/or bell has been excavated to the specified dimensions at the correct depth established by the previously mentioned criteria;

• An acceptable portion of the shaft penetrates the underlying soil for the recommended deign parameters;

• The bell is concentric with the pier shaft; • The shaft has been drilled plumb within specified tolerances along its total length; and • Excessive cuttings, buildup and soft, compressible materials have been removed from

the bottom of the excavation. Due to the presence of hard soil, high-powered, high-torque drilling equipment should be anticipated for drilled pier construction at this site (see also Excavation Equipment). Reinforcement and Concrete Placement Reinforcing steel should be checked for size and placement prior to concrete placement. Placement of concrete should be accomplished as soon as possible after excavation to reduce changes in the moisture content or the state of stress of the foundation materials. No foundation element should be left open overnight without concreting.


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Temporary Casing Groundwater seepage and/or side sloughing may to be encountered at the time of construction, depending on climatic conditions prevalent at the time of construction. Therefore, we recommend that the bid documents require the foundation contractor to specify unit costs for different lengths of casing that may be required. CRAWL SPACE CONSIDERATIONS If the structurally suspended floor system described as Alternative No. 1 under the Floor Slab section of this report is selected, several special design issues should be considered for the resulting subfloor crawl space. These issues are discussed below. Ventilation Observations by members of our firm of open crawl spaces have indicated a need for adequate subfloor ventilation for suspended floor systems. Such ventilation helps promote evaporation of subgrade moisture which may accumulate in spite of special surface and subsurface drainage features. As a minimum, free flowing passive vents may need to be installed along the perimeter beam to provide cross ventilation. If structural configurations will limit the free flow of air through passive vents, forced air, power vents should be installed. All vents should be designed such that they will not allow the drainage of surface water into the crawl space. Below Slab Utilities A minimum clearance of 12 in. has been recommended between both the grade beams and floor slab and the underlying finished subgrade should a suspended floor system be employed. Such a minimum clearance is also recommended between the subgrade and any utilities which may be suspended from the underside of the floor. This clearance will allow swell-related subgrade movements without damaging the utilities. It is recommended that the utility clearance not be provided by the addition of narrow trenches running parallel to and immediately below the utilities, unless proper slopes and drainage outlets are provided to prevent ponding of water in the trenches. Drainage As discussed throughout this report, positive drainage is a key factor in the long term performance of any foundation. This is not only critical around the perimeter of the structure, but also in any subfloor crawl spaces. In crawl areas, surface drainage should be established that will direct water away from and will prevent water from ponding adjacent to piers. This positive drainage should be maintained both prior to and after construction. Compaction control of the backfill around the perimeter of the building following the placement of soil retainer blocks is critical to the drainage away from the building following construction. Materials for the backfill around the perimeter of the building should be the on-site clays. These materials should be compacted in uniformly thin lifts (8-inch maximum loose thickness) to at least 95 percent of the maximum dry density as determined by TxDOT Test Method TEX-114-E. These clays should be placed and compacted at optimum to plus 3 percent above optimum moisture content. Compaction by hand operated mechanical tampers will help to avoid damage to the soil retainer blocks. Following backfilling operations the soil retainer blocks should be checked to see that they have not been broken or collapsed during the compaction operations. Any soil retainer blocks that are broken or collapsed should be repaired or replaced. Carton Forms When carton forms are used to form subfloor void spaces, the forms often get wet or sometimes absorb water from humid air. This can result in collapse of the forms during the placement of concrete, thus diminishing the design void space. Conversely, if the carton forms are too strong and do not decompose


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sufficiently with time, they may not collapse as soil heave occurs, resulting in heave damage to the floor slab. Where there is sufficient moisture to cause the appropriate deterioration after construction, there may be a resulting moisture problem in the floor slab as a result of poor ventilation and the accumulation of condensation within the resulting unventilated void space. The lack of ventilation may also result in increased soil movements that will diminish the design void space. If project specifics require the use of carton forms, then as a minimum, care should be taken to ensure that the carton forms are designed for use in the project location, and that carton forms are properly stored, protected, and installed during construction. TEMPORARY EXCAVATION SLOPING AND BENCHING In areas where back slopes are feasible and have heights less than 20 ft, excavation slopes should be consistent with safety regulations. Worker safety and classification of soil type is the responsibility of the contractor. The materials encountered during excavations for the proposed project are anticipated to consist of fine-grained soil that can generally be classified as OSHA Type B soils. However, in some of the borings the underlying clay was blocky or slickensided. Hence, when these types of soils are encountered the soil should be classified as OSHA Type C. OSHA guidelines provide for temporary slopes performed in Type B materials to be constructed at 1 Vertical: 1 Horizontal or flatter. If water is encountered in the localized sand layer (Boring TP-30121-01) or if blocky/slickensided clays are encountered, OSHA guidelines for temporary slopes performed in Type C materials should be constructed at 1 Vertical: 1.5 Horizontal or flatter. Excavations extending deeper than 20 ft must be evaluated by a professional engineer.

The contractor should be aware that excavation depths and inclinations (including adjacent existing slopes) should not exceed those specified in local, state or federal safety regulations, e.g., OSHA Health and Safety Standards for Excavations, 29 CFR Part 1926, or successor regulations. Such regulations are strictly enforced and, if not followed, the contractor, or earthwork or utility subcontractors could be subjected to substantial penalties. Construction site safety is the sole responsibility of the contractor, who shall also be solely responsible for the means, methods and sequencing of construction operations. Temporary slopes left open may undergo sloughing and result in an unstable situation. The contractor should evaluate stability and failure consequences before open cut slopes are made. Minor sloughing of open face slopes may occur. If the slope is expected to remain open for an extended time, an impermeable membrane covering the slopes could be considered as a means to reduce the potential for slope degradation and instability. It is important to note that soils encountered in the construction excavations may vary across the site and that even if the OSHA criteria are used, there is a potential for slope failure. If different subsurface conditions are encountered at the time of construction, RKCI should be contacted to evaluate the conditions encountered. An excavated temporary slope may not be feasible at all locations, and a temporary retention system may be required. While many different types and configurations can be used, the more common types, and applicable to this site, are soldier pile and lagging and tangent walls (closely spaced drilled piers). Design of temporary shoring systems is beyond the scope of our services. The design of the system should be performed by the contractor that performs the work. The contractor should also be responsible for monitoring the stability of the retention system.

EXCAVATION EQUIPMENT Our boring logs are not intended for use in determining construction means and methods and may therefore be misleading if used for that purpose. We recommend that earthwork and utility contractors interested in bidding on the work perform their own tests in the form of test pits to determine the quantities of the different materials to be excavated, as well as the preferred excavation methods and equipment for this site.


24

If this report is provided to prospective contractors, the Team should make it clear that the information is provided for factual data only and not as a warranty of subsurface conditions included in this report. Unanticipated soil or rock conditions could require the expenditure of additional funds to attain a properly constructed project. Therefore, some contingency fund is recommended to accommodate such potential extra costs. PERMANENT SLOPES Site grading plans are unavailable at this time. The stability of permanent slopes depends on many factors, including the height and geometry of the slopes, the types of soils contained in the slopes, effects of groundwater, and any surface pressures present. In general, permanent cut and fill slopes, constructed at 1V:3H (1 vertical on 3 horizontal) have been observed to perform satisfactorily. Therefore, it is our opinion that slopes should be constructed at 1V:3H or flatter. Fill slopes should be constructed by extending the compacted fill beyond the planned profile of the slope and then trimming the slope to the desired configuration. Cut slopes can be designed similar to fill slopes. However, the potential for sloughing and/or general slope failure increases with an increase in the steepness and depth of cut, particularly if low strength soil occurs in or near the base of the slope. UTILITIES Utilities which project through slab-on-grade, slab-on-fill, or any other rigid unit should be designed with either some degree of flexibility or with sleeves. Such design features will help reduce the risk of damage to the utility lines as vertical movements occur. These types of slabs will generally be constructed as monolithic, grid type beam and slab foundations. Our experience indicates that significant settlement of backfill can occur in utility trenches, particularly when trenches are deep, when backfill materials are placed in thick lifts with insufficient compaction, and when water can access and infiltrate the trench backfill materials. The potential for water to access the backfill is increased where water can infiltrate flexible base materials due to insufficient penetration of curbs, and at sites where geological features can influence water migration into utility trenches (such as fractures within a rock mass or at contacts between rock and clay formations). It is our belief that another factor which can significantly impact settlement is the migration of fines within the backfill into the open voids in the underlying free-draining bedding material. To reduce the potential for settlement in utility trenches, we recommend that consideration be given to the following:

• All backfill materials should be placed and compacted in controlled lifts appropriate for the type of backfill and the type of compaction equipment being utilized and all backfilling procedures should be tested and documented.

• Curbs should completely penetrate base materials, if any, and be installed to a sufficient depth to reduce water infiltration beneath the curbs into the pavement base materials.

• Consideration should be given to encapsulating free-draining bedding gravels with a geotextile fabric (similar to Mirafi 140N) to reduce the infiltration and loss of fines from backfill material into the interstitial voids in bedding materials.

PAVEMENT RECOMMENDATIONS

SUBGRADE CONDITIONS We have assumed the subgrade in pavement areas will consist of recompacted on-site clays, placed and compacted as recommended in the On-Site Clay Fill section of this report. Based on our experience with similar subgrade soils and the results of the DCP tests, we have assigned a California Bearing Ratio (CBR) value of 3 for use in pavement thickness design analyses.


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DESIGN INFORMATION The following recommendations were prepared using the DARWin 3.1 software program which utilizes a procedure based on the 1993 “Guide for the Design of Pavement Structures” by the American Association of State Highway and Transportation Officials (AASHTO). The following recommendations were prepared assuming a 20-yr design life and Equivalent Single Axle Loads (ESALs) of 279,000 for light duty pavements and 780,000 for heavy duty pavements. The Project Civil Engineer should review anticipated traffic loading and frequencies to verify that the assumed design ESALs are appropriate for the intended use of the facility. PAVEMENT DESIGN PARAMETERS – HOT MIX ASPHALT PAVEMENTS The following input variables are utilized to design flexible pavements (commonly referred to as Asphaltic Cement Concrete or Asphalt pavements) when using the procedures detailed in the 1993 AASHTO Guide for Design of Pavement Structures:

• Performance Period • Roadbed Soil Resilient Modulus psi • Serviceability Indices • Overall Standard Deviation • Reliability, % • Design Traffic, 18-kip ESALs

Performance Period The pavement structure was designed for a 20-year performance period which is typical for most flexible pavements. Roadbed Soil Resilient Modulus The Resilient Modulus (MR) is the material property used to characterize the support characteristics of the roadbed soils in flexible pavement design. It is a measure of the soil’s deformation response to cyclic applications of loads much smaller than a failure load. Using conventional correlations, local experience and a design CBR value of 3, a Resilient Modulus of 4,500 psi has been used for this project. To determine the resilient modulus (Mr) of the subgrade, we utilized the correlation equation proposed for the latest version of the AASHTO Mechanistic-Empirical Pavement Design Guide (ME-PDG). The equation is shown below:

Mr = 1,500 x CBR Serviceability Indices Initial serviceability is a measure of the pavement's smoothness or rideability immediately after construction. Terminal serviceability is the minimum tolerable serviceability of a pavement. When the serviceability of a pavement reaches its terminal value, rehabilitation is required. An initial serviceability value of 4.2 and a terminal serviceability value of 2 were used for this pavement design, which results in a change of serviceability of 2.2. Overall Standard Deviation Overall standard deviation accounts for both chance variation in the traffic prediction and normal variation in pavement performance prediction for a given traffic. Higher values represent more variability; thus, the pavement thickness increases with higher overall standard deviations. A value of 0.45 is used for this pavement design.


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Reliability, % The reliability value represents a "safety factor," with higher reliabilities representing pavement structures with less chance of failure. The AASHTO Guide recommends values ranging from 50 to 99.9%, depending on the functional classification and the location (urban vs. rural) of the roadway. A reliability of 70% is used for this pavement design. Design Traffic 18-kip ESAL The specified 18-kip ESALs in the Design Information section of this report was used in our design. Design Structural Number The structural number of any pavement cross section is related to the CBR value of the pavement subgrade and the volume of traffic that the pavement will carry over its service life. The CBR provides an estimate of the relative strength of the subgrade and consequently indicates the ability of the pavement section to carry load. This site-specific CBR value is utilized in conjunction with specific pavement design parameters as well as the pavement Structural Number (SN) to analyze the amount of traffic that a specific pavement cross section can accommodate over the design life. Using the ESAL values as well as the above design data, the minimum required structural number (SN) of 2.91 for light duty traffic and 3.40 for heavy duty traffic was calculated using the DARWin program. RECOMMENDED PAVEMENT SECTIONS - HOT MIX ASPHALT PAVEMENT Flexible pavement sections recommended for this site are as listed in the table below:

Traffic Type

Flexible Pavement Components

Flexible Base (in.) Surface Course (in.)

Light Duty Traffic (parking areas)

11

3

Heavy Duty Traffic (entrances, driveways, and channelized)

11

4

Based on our experience, the reported sections often perform adequately; however, maintenance or an overlay is generally needed sooner than would be required for a thicker design section. Consideration could be given to adding additional asphalt (i.e. an additional 1 in.) or incorporating a geotextile or geogrid below the flexible base. These are options and are not required. The geogrid reinforcement should be similar to TxDOT Type 2 Geogrid, Tensar TX 5 or an approved substitute. Alternatives must include a physical sample and a report of documented physical properties, including but not limited to laboratory measured torsional rigidity (COE Method), junction strength and junction efficiency (GRI GGI-87), tensile strength (ASTM D-6637-01), and tensile modulus (GRI GGI-87). In addition, submittals should include results of full-scale laboratory testing or in-ground testing quantifying the structural contribution of the geogrid to a pavement structure.

PAVEMENT DESIGN PARAMETERS – PORTLAND CEMENT CONCRETE PAVEMENTS The following input variables are utilized to design rigid pavements (commonly referred to as Portland Cement Concrete or PCC pavements) when using the procedures detailed in the 1993 AASHTO Guide for Design of Pavement Structures:

• Performance Period • 28-day Concrete Modulus of Rupture, psi • 28-day Concrete Elastic Modulus, psi


27

• Effective Modulus of Subbase/Subgrade Reaction, pci • Serviceability Indices • Load Transfer Coefficient • Drainage Coefficient • Overall Standard Deviation • Reliability, % • Design Traffic, 18-kip ESALs

Performance Period The pavement structure was designed for a 30-year performance period which is typical for most rigid pavements. 28-day Concrete Modulus of Rupture, Mr The Mr of concrete is a measure of the flexural strength of the concrete as determined by breaking concrete beam test specimens. A Mr of 600 psi at 28 days is used with the current TxDOT statewide specification for concrete pavement design. 28-day Concrete Elastic Modulus Elastic modulus of concrete is an indication of concrete stiffness and varies depending on the coarse aggregate type used in the concrete. A modulus of 4,000,000 psi is used for this pavement design. Effective Modulus of Subbase/Subgrade Reaction: k-value Concrete slab support is characterized by the modulus of subgrade/subbase reaction, otherwise known as the k-value with units typically shown as psi/in. A k-value of 100 psi/in. was used in the rigid pavement design procedure and is based upon the CBR value of 3. Serviceability Indices Initial serviceability is a measure of the pavement's smoothness or rideability immediately after construction. Terminal serviceability is the minimum tolerable serviceability of a pavement. When the serviceability of a pavement reaches its terminal value, rehabilitation is required. An initial serviceability value of 4.5 and a terminal serviceability value of 2 were used for this pavement design, which results in a change of serviceability of 2.5. Load Transfer Coefficient The load transfer coefficient is used to incorporate the effect of dowels, reinforcing steel, tied shoulders, and tied curb and gutter on reducing the stress in the concrete slab due to traffic loading and therefore causing a reduction in the required concrete slab thickness. The coefficients recommended in the AASHTO Guide are based on findings from the AASHO Road Test. The following table presents the recommended Load Transfer Coefficients as presented in the TXDOT Pavement Design Guide.

CRCP or Load transfer devices at transverse joints

Tied PCC shoulders, curb and gutter, or greater than two lanes in one direction

Yes No

Yes 2.6 3.2

No 3.7 4.2


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We assume a Continuously Reinforced Concrete Pavement (CRCP) or load transfer devices at transverse joints was selected and the load transfer coefficient used in this pavement design is 3.2. RKCI recommends that tied PCC shoulders be provided, if sufficient right-of-way (ROW) is available or there are no other geometric constraints. In case it is not feasible to provide tied PCC shoulders, the use of a minimum 2-ft wide outside lane should be considered. Drainage Coefficient The drainage coefficient characterizes the quality of drainage of the subgrade layers under the concrete slab. Good draining pavement structures do not give water the chance to saturate the subbase and subgrade; thus, pumping is not as likely to occur. The following table presents the recommended Drainage Coefficients as presented in the TXDOT Pavement Design Guide.

Annual Rainfall (inches) Drainage Coefficients

58 – 50 0.91 - 0.95

48 – 40 0.96 - 1.00

38 – 30 1.01 - 1.05

28 – 20 1.06 - 1.10

18 – 8 1.11 - 1.16

NOTE: Higher drainage coefficients decrease the pavement thickness in the AASHTO procedure.

The subbase recommended by TxDOT for PCC pavements is a 4 in. ACP subbase or Granular Base. Due to the presence of relatively high PI soils at this site, we recommend using ACP subbase to reduce the potential for water saturating the underlying subgrade. Therefore, the drainage coefficient used in this pavement design is 1.05, and is based upon local design experience and table above. Overall Standard Deviation Overall standard deviation accounts for both chance variation in the traffic prediction and normal variation in pavement performance prediction for a given traffic. Higher values represent more variability; thus, the pavement thickness increases with higher overall standard deviations. A value of 0.35 is used for this rigid pavement design. Reliability, % The reliability value represents a "safety factor," with higher reliabilities representing pavement structures with less chance of failure. The AASHTO Guide recommends values ranging from 50% to 99.9%, depending on the functional classification and the location (urban vs. rural) of the roadway. A reliability of 70% was selected for this rigid pavement design. Design Traffic 18-kip ESAL The specified 18-kip ESALs in the Design Information section of this report was used in our design. RECOMMENDED PAVEMENT SECTIONS - RIGID PAVEMENT We recommend that rigid pavement sections at this site consist of the following:


29

Traffic Type Portland Cement Concrete

Light Duty Traffic 5 in.

Heavy Duty Traffic 6 in. With effective preconstruction planning and proper construction practices, unreinforced pavements may be considered for the concrete pavements. However, if the concrete pavements are to be reinforced with welded wire mats or bar mats, we recommend the following reinforcement. As a minimum, the welded wire mats should be 6 x 6 in., W4.0 x W4.0, and the bar mats should be No. 3 reinforcing bars spaced 18 in. on center in both directions. The concrete reinforcing should be placed approximately 1/3 the slab thickness below the surface of the slab, but not less than 2 in. The reinforcing should not extend across expansion joints. Joints in concrete pavements aid in the construction and control the location and magnitude of cracks. Where practical, lay out the construction, expansion, control and sawed joints to form square panels, but not to exceed ACI 302.69 Code recommendations. The ratio of slab length-to-width should not exceed 1.25. Recommended joint spacings are 15 ft longitudinal and 15 ft transverse. All control joints should be formed or sawed to a depth of at least 1/4 the thickness of the concrete slab. Sawing of control joints should begin as soon as the concrete will not ravel, generally the day after placement. Control joints may be hand formed or formed by using a premolded filler. We recommend that all longitudinal and transverse construction joints be dowelled to promote load transfer. Expansion joints are needed to separate the concrete slab from fixed objects such as drop inlets, light standards and buildings. Expansion joint spacings are not to exceed a maximum of 75 ft and no expansion or construction joints should be located in a swale or drainage collection locations. If possible, the pavement should develop a minimum slope of 0.015 ft/ft to provide surface drainage. Reinforced concrete pavement should cure a minimum of 3 and 7 days before allowing automobile and truck traffic, respectively.

PAVEMENT CONSTRUCTION CONSIDERATIONS SUBGRADE PREPARATION Areas to support pavements should be stripped of all vegetation and organic topsoil and the exposed subgrade should be proofrolled in accordance with the recommendations in the Site Preparation section under Foundation Construction Considerations. After completion of the proofrolling operations and just prior to flexible base placement, the exposed subgrade should be moisture conditioned by scarifying to a minimum depth of 6 in. and recompacting to a minimum of 95 percent of the maximum density determined by Tex-114-E. The moisture content of the subgrade should be maintained within the range of optimum moisture content to 3 percentage points above optimum until permanently covered. DRAINAGE CONSIDERATIONS As with any soil-supported structure, the satisfactory performance of a pavement system is contingent on the provision of adequate surface and subsurface drainage. Insufficient drainage which allows saturation of the pavement subgrade and/or the supporting granular pavement materials will greatly reduce the performance and service life of the pavement systems. Surface and subsurface drainage considerations crucial to the performance of pavements at this site include (but are not limited to) the following:


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1) Any known natural or man-made subsurface seepage at the site which may occur at sufficiently shallow depths as to influence moisture contents within the subgrade should be intercepted by drainage ditches or below grade French drains.

2) Final site grading should eliminate isolated depressions adjacent to curbs which may allow surface water to pond and infiltrate into the underlying soils. Curbs should completely penetrate base materials, if any, and should be installed to sufficient depth to reduce infiltration of water beneath the curbs.

3) Pavement surfaces should be maintained to help minimize surface ponding and to provide rapid sealing of any developing cracks. These measures will help reduce infiltration of surface water downward through the pavement section.

ON-SITE CLAY FILL As discussed previously, the pavement recommendations presented in this report were prepared assuming that on-site soils will be used for fill grading in proposed pavement areas. If used, we recommend that on-site soils be placed in loose lifts not exceeding 8 in. in thickness and compacted to at least 95 percent of the maximum density as determined by Tex-114-E. The moisture content of the fill should be maintained within the range of optimum water content to 3 percentage points above the optimum water content until permanently covered. We recommend that fill materials be free of roots and other organic or degradable material. We also recommend that the maximum particle size not exceed 4 in. or one half the lift thickness, whichever is smaller. TREATMENT OF SUBGRADE Lime treatment or cement treatment of the subgrade soils, should be in accordance with the TxDOT Standard Specifications, Item 260 or Item 275, respectively. A sufficient quantity of hydrated lime or cement should be mixed with the subgrade soils to reduce the soil-lime mixture plasticity index to 20 or less. Based on the experience with similar soils we recommend that at least 5 percent of hydrated lime or 6 percent cement by weight be used to reduce the PI of the subgrade clays. Treated subgrade soils should be compacted to a minimum of 95 percent of the maximum density within zero to plus 3 percentage points of the optimum moisture content as determined by TxDOT Test Method Tex-113-E. If lime treatment is considered as a method to improve pavement subgrade conditions, it is also recommended to perform additional laboratory testing to verify the concentration of soluble sulfates in the subgrade soils, in order to investigate the potential for an adverse reaction to lime or cement in sulfate-containing soils. The adverse reaction, referred to as sulfate-induced heave, has been known to cause cohesive subgrade soils to swell in short periods of time, resulting in pavement heaving and possible failure. FLEXIBLE BASE COURSE The flexible base course should be crushed limestone conforming to TxDOT Standard Specifications, Item 247, Type A, Grade 1-2. Base course should be placed in lifts with a maximum thickness of 8 in. and compacted to a minimum of 95 percent of the maximum density at a moisture content within the range of 2 percentage points below to 2 percentage points above the optimum moisture content as determined by Tex-113-E. ASPHALTIC CONCRETE SURFACE COURSE The asphaltic concrete surface course should conform to TxDOT Standard Specifications, Item 340, Type C or D. The asphaltic concrete should be compacted to a minimum of 92 percent of the maximum theoretical specific gravity (Rice) of the mixture determined according to Test Method Tex-227-F. Pavement specimens, which shall be either cores or sections of asphaltic pavement, will be tested according to Test Method Tex-207-F. The nuclear-density gauge or other methods which correlate satisfactorily with results obtained from project roadway specimens may be used when approved by the Engineer. Unless otherwise shown on the plans, the Contractor shall be responsible for obtaining the required roadway specimens at their expense and in a manner and at locations selected by the Engineer.


31

PORTLAND CEMENT CONCRETE The Portland cement concrete should be air entrained to result in a 4 percent plus/minus 1 percent air, should have a maximum slump of 5 inches, and should have a minimum 28-day compressive strength of 3,000 psi. A liquid membrane-forming curing compound should be applied as soon as practical after broom finishing the concrete surface. The curing compound will help reduce the loss of water from the concrete. The reduction in the rapid loss in water will help reduce shrinkage cracking of the concrete. The Mr of concrete is a measure of the flexural strength of the concrete as determined by breaking concrete beam test specimens. A Mr of approximately 450 to 550 psi at 28 days was used in the analysis and is typical of local concrete production.

CONSTRUCTION RELATED SERVICES

CONSTRUCTION MATERIALS TESTING AND OBSERVATION SERVICES As presented in the attachment to this report, Important Information About Your Geotechnical Engineering Report, subsurface conditions can vary across a project site. The conditions described in this report are based on interpolations derived from a limited number of data points. Variations will be encountered during construction, and only the geotechnical design engineer will be able to determine if these conditions are different than those assumed for design. Construction problems resulting from variations or anomalies in subsurface conditions are among the most prevalent on construction projects and often lead to delays, changes, cost overruns, and disputes. These variations and anomalies can best be addressed if the geotechnical engineer of record, RKCI is retained to perform construction observation and testing services during the construction of the project. This is because:

• RKCI has an intimate understanding of the geotechnical engineering report’s findings and recommendations. RKCI understands how the report should be interpreted and can provide such interpretations on site, on the client’s behalf.

• RKCI knows what subsurface conditions are anticipated at the site. • RKCI is familiar with the goals of the owner and project design professionals, having

worked with them in the development of the geotechnical workscope. This enables RKCI to suggest remedial measures (when needed) which help meet the owner’s and the design teams’ requirements.

• RKCI has a vested interest in client satisfaction, and thus assigns qualified personnel whose principal concern is client satisfaction. This concern is exhibited by the manner in which contractors’ work is tested, evaluated and reported, and in selection of alternative approaches when such may become necessary.

• RKCI cannot be held accountable for problems which result due to misinterpretation of our findings or recommendations when we are not on hand to provide the interpretation which is required.

BUDGETING FOR CONSTRUCTION TESTING Appropriate budgets need to be developed for the required construction testing and observation activities. At the appropriate time before construction, we advise that RKCI and the project designers meet and jointly develop the testing budgets, as well as review the testing specifications as it pertains to this project. Once the construction testing budget and scope of work are finalized, we encourage a preconstruction meeting with the selected contractor to review the scope of work to make sure it is consistent with the construction means and methods proposed by the contractor. RKCI looks forward to the opportunity to provide continued support on this project, and would welcome the opportunity to meet with the Project Team to develop both a scope and budget for these services.

* * * * * * * * * * * * * * * * * *

ATTACHMENTS

APPENDIX A Supplemental Recommendations and Considerations

(This Page Left Intentionally Blank)

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ELECTRICALBUILDING BOOSTER

PUMP PAD

CHEMICALBUILDING

TRANSFORMERPAD

DCP-2

DCP-1

DCP-3

US HWY 290

T-30121-04

T-30121-03T-30121-02

T-30121-01

CE-30121-01BP-30121-01

TP-30121-01CE-30121-02

BORING LOCATION MAPVISTA RIDGE - REGIONAL SUPPLY PROJECT

IPS #1BASTROP COUNTY, TEXAS

PROJECT No.:ASA15-051-00

DRAWN BY:ISSUE DATE:

REVIEWED BY:CHECKED BY:

CCL09/06/2016

EJNIM

NOTE: This Drawing is Provided for Illustration Only, May Not be to Scale and is Not Suitable for Design or Construction Purposes

µLEGEND!? BORING") DCP TEST LOCATION

PROPOSED ALIGNMENTPROPOSED STRUCTUREPROPOSED TANK

Elgin

£¤290

£¤290

UV95

UV95

UV95

Bastrop

SITE LOCATION MAP

S I T E

FIGURE1BASTROP

COUNTY

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TBPE Firm Number 3257

12821 West Golden LaneSan Antonio, Texas 78249

(210)699-9090 TEL(210)699-6426 FAX

www.rkci.com

0 60 12030Feet

1 INCH = 120 FEET

112

CLAY, Stiff to Hard, Dark Brown, with tansand

SAND, Clayey, Medium Dense, Tan

CLAY, Blocky, Very Stiff, Gray to Dark Gray,with ferric staining

- with sand from 8 ft to 10 ft

Boring Terminated

25

52

NOTES:* Elevation estimated from Google Earth.

48

LOG OF BORING NO. TP-30121-01

PLA

STIC

ITY

IND

EX

SURFACE ELEVATION: 568* ft

Straight Flight Auger

% -2

00

DRILLINGMETHOD: LOCATION:

PLASTICLIMIT

LIQUIDLIMIT

WATERCONTENT

BLO

WS

PER

FT

10 20 30 40 50 60 70 80

DESCRIPTION OF MATERIAL0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

SHEAR STRENGTH, TONS/FT2

UN

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pcf

N 30.32953; W 97.34103

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DEPTH DRILLED:DATE DRILLED:

DEPTH TO WATER:DATE MEASURED:

5

10

15

20

25

30

35

SYM

BOL

SAM

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VISTA RIDGE REGIONAL SUPPLY PROJECTTEXAS

DRY8/11/2016

DEP

TH, F

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25.0 ft8/11/2016

ASA15-051-002

PROJ. No.:FIGURE:

TBPE Firm Registration No. F-3257

12

21

27

21

103

CLAY, Stiff to Very Stiff, Dark Brown

CLAY, Blocky, Hard to Very Stiff, GrayishBrown

- with tan sand seams from 18 ft to 20 ft

Boring Terminated

51

42

LOG OF BORING NO. CE-30121-01

PLA

STIC

ITY

IND

EX

SURFACE ELEVATION: 566 ft


% -2

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PLASTICLIMIT

LIQUIDLIMIT

WATERCONTENT

BLO

WS

PER

FT

10 20 30 40 50 60 70 80



UN

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pcf

N 30.33004; W 97.34130

NO

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20

25

30

35

SYM

BOL

SAM

PLES


DRY8/11/2016

DEP

TH, F

T

25.0 ft8/11/2016

ASA15-051-003

PROJ. No.:FIGURE:


14

23

24

27

27

103

CLAY, Silty, Stiff, Dark Brown

CLAY, Silty, Very Stiff to Hard, Tan, with sandand ferric staining

CLAY, Very Stiff to Hard, Gray to Dark Gray,with ferric staining

Boring Terminated

23

65

LOG OF BORING NO. CE-30121-02

PLA

STIC

ITY

IND

EX

SURFACE ELEVATION: 566 ft


% -2

00


PLASTICLIMIT

LIQUIDLIMIT

WATERCONTENT

BLO

WS

PER

FT

10 20 30 40 50 60 70 80



UN

IT D

RYW

EIG

HT,

pcf

N 30.32968; W 97.34109

NO

TE: T

HES

E LO

GS

SHO

ULD

NO

T BE

USE

D S

EPAR

ATEL

Y FR

OM

TH

E PR

OJE

CT R

EPO

RT



5

10

15

20

25

30

35

SYM

BOL

SAM

PLES


DRY8/11/2016

DEP

TH, F

T

25.0 ft8/11/2016

ASA15-051-004

PROJ. No.:FIGURE:


11

13

41

19

34

102

112

96

99

113

CLAY, Stiff to Hard, Dark Brown

CLAY, Stiff to Hard, Tan and Gray, withferrous stains

CLAY, Hard, Dark Gray, with ferrous stains

Boring Terminated

38

36


LOG OF BORING NO. BP-30121-01

PLA

STIC

ITY

IND

EX



% -2

00


PLASTICLIMIT

LIQUIDLIMIT

WATERCONTENT

BLO

WS

PER

FT

10 20 30 40 50 60 70 80



UN

IT D

RYW

EIG

HT,

pcf

N 30.33003; W 97.34093

NO

TE: T

HES

E LO

GS

SHO

ULD

NO

T BE

USE

D S

EPAR

ATEL

Y FR

OM

TH

E PR

OJE

CT R

EPO

RT



5

10

15

20

25

30

35

SYM

BOL

SAM

PLES


DRY8/10/2016

DEP

TH, F

T

25.0 ft8/10/2016

ASA15-051-005

PROJ. No.:FIGURE:


9

23

41

30

103

110

93

100

90

CLAY, Stiff, Brown

CLAY, Blocky, Hard to Very Stiff, Tan andGray, with ferric staining

- slickensided

CLAY, Blocky, Hard, Dark Gray, with lignitedeposits

53

26

54

94

100

LOG OF BORING NO. T-30121-01

PLA

STIC

ITY

IND

EX



% -2

00


PLASTICLIMIT

LIQUIDLIMIT

WATERCONTENT

BLO

WS

PER

FT

10 20 30 40 50 60 70 80



UN

IT D

RYW

EIG

HT,

pcf

N 30.32965; W 97.34053

NO

TE: T

HES

E LO

GS

SHO

ULD

NO

T BE

USE

D S

EPAR

ATEL

Y FR

OM

TH

E PR

OJE

CT R

EPO

RT



5

10

15

20

25

30

35

SYM

BOL

SAM

PLES


DRY8/10/2016

DEP

TH, F

T

50.0 ft8/10/2016

ASA15-051-006a

PROJ. No.:FIGURE:


9

13

29

33

23

46

100

CLAY, Blocky, Hard, Dark Gray, with lignitedeposits (continued)

Boring Terminated



PLA

STIC

ITY

IND

EX



% -2

00


PLASTICLIMIT

LIQUIDLIMIT

WATERCONTENT

BLO

WS

PER

FT

10 20 30 40 50 60 70 80



UN

IT D

RYW

EIG

HT,

pcf

N 30.32965; W 97.34053

NO

TE: T

HES

E LO

GS

SHO

ULD

NO

T BE

USE

D S

EPAR

ATEL

Y FR

OM

TH

E PR

OJE

CT R

EPO

RT



45

50

55

60

65

70

75

SYM

BOL

SAM

PLES


DRY8/10/2016

DEP

TH, F

T

50.0 ft8/10/2016

ASA15-051-006b

PROJ. No.:FIGURE:


41

101

90

100

CLAY, Firm, Dark Brown

CLAY, Blocky, Firm to Hard, Tan and Gray,with ferric staining

CLAY, Very Stiff, Dark Gray, with lignitedeposits

Boring Terminated

37

37


88


PLA

STIC

ITY

IND

EX



% -2

00


PLASTICLIMIT

LIQUIDLIMIT

WATERCONTENT

BLO

WS

PER

FT

10 20 30 40 50 60 70 80



UN

IT D

RYW

EIG

HT,

pcf

N 30.32984; W 97.34071

NO

TE: T

HES

E LO

GS

SHO

ULD

NO

T BE

USE

D S

EPAR

ATEL

Y FR

OM

TH

E PR

OJE

CT R

EPO

RT



5

10

15

20

25

30

35

SYM

BOL

SAM

PLES


DRY8/10/2016

DEP

TH, F

T

30.0 ft8/10/2016

ASA15-051-007

PROJ. No.:FIGURE:


6

8

40

50/11"

33

109

CLAY, Blocky, Firm to Hard, Tan and Gray

- with sand from 10 ft to 20 ft- with ferric staining from 10 ft to 30 ft

Boring Terminated

39



PLA

STIC

ITY

IND

EX



% -2

00


PLASTICLIMIT

LIQUIDLIMIT

WATERCONTENT

BLO

WS

PER

FT

10 20 30 40 50 60 70 80



UN

IT D

RYW

EIG

HT,

pcf

N 30.32987; W 97.34035

NO

TE: T

HES

E LO

GS

SHO

ULD

NO

T BE

USE

D S

EPAR

ATEL

Y FR

OM

TH

E PR

OJE

CT R

EPO

RT



5

10

15

20

25

30

35

SYM

BOL

SAM

PLES


DRY8/10/2016

DEP

TH, F

T

30.0 ft8/10/2016

ASA15-051-008

PROJ. No.:FIGURE:


6

8

33

50/8"

50

103

100

94

96

CLAY, Firm, Brown

CLAY, Hard to Firm, Tan and Gray

- silty with ferric staining from 8 ft to 20 ft

- blocky from 20 ft to 25 ft

CLAY, Gray, with ferric staining

Boring Terminated

48

27

35


100


PLA

STIC

ITY

IND

EX



% -2

00


PLASTICLIMIT

LIQUIDLIMIT

WATERCONTENT

BLO

WS

PER

FT

10 20 30 40 50 60 70 80



UN

IT D

RYW

EIG

HT,

pcf

N 30.32951; W 97.34053

NO

TE: T

HES

E LO

GS

SHO

ULD

NO

T BE

USE

D S

EPAR

ATEL

Y FR

OM

TH

E PR

OJE

CT R

EPO

RT



5

10

15

20

25

30

35

SYM

BOL

SAM

PLES


DRY8/10/2016

DEP

TH, F

T

30.0 ft8/10/2016

ASA15-051-009

PROJ. No.:FIGURE:


8

20

46

50/10"


CLAY-SHALE

SAMPLE TYPES

NO INFORMATION

BLANK PIPE

ASPHALT

IGNEOUS

LIMESTONE

FILL

GEOPROBESAMPLER

TEXAS CONEPENETROMETER

DISTURBED

METAMORPHIC

MARL

MUDROTARY

NORECOVERY SPLIT BARREL

SPLIT SPOONNX CORE

SHELBY TUBE

CALCAREOUS

CLAY

CLAYEY

GRAVEL

GRAVELLY

WELL CONSTRUCTION AND PLUGGING MATERIALS

SILTSTONE

CALICHE

CONGLOMERATE

AIRROTARY

GRABSAMPLE

DOLOMITE

BENTONITE

CORE

SOIL TERMS OTHER

NOTE: VALUES SYMBOLIZED ON BORING LOGS REPRESENT SHEARSTRENGTHS UNLESS OTHERWISE NOTED

BASE

KEY TO TERMS AND SYMBOLS

CUTTINGS

SAND

SANDY

SILT

SILTY

CHALK

STRENGTH TEST TYPES

CEMENT GROUT GRAVEL

SAND

POCKET PENETROMETER

TORVANE

UNCONFINED COMPRESSION

TRIAXIAL COMPRESSIONUNCONSOLIDATED-UNDRAINED

TRIAXIAL COMPRESSIONCONSOLIDATED-UNDRAINED

BRICKS /PAVERS

SCREEN

MATERIAL TYPES

VOLCLAY

SANDSTONE

SHALE

ROCK TERMS

WASTE

CONCRETE/CEMENT

PEAT

BENTONITE &CUTTINGS

CONCRETE/CEMENT

CLAYSTONE

ROTOSONIC-DAMAGED

ROTOSONIC-INTACT

PITCHER

FIGURE 10aREVISED 04/2012


KEY TO TERMS AND SYMBOLS (CONT'D)

TERMINOLOGY

RELATIVE DENSITY PLASTICITYCOHESIVE STRENGTH

PenetrationResistance

Blows per ftDegree ofPlasticity

PlasticityIndex

RelativeDensity

ResistanceBlows per ft

0

4

10

30

-

-

-

-

>

4

10

30

50

50

Very Loose

Loose

Medium Dense

Dense

Very Dense

ConsistencyCohesion

TSF

-

-

-

-

>

-

-

-

-

-

>

Benzene

Toluene

Ethylbenzene

Total Xylenes

Total BTEX

Total Petroleum Hydrocarbons

Not Detected

Not Analyzed

Not Recorded/No Recovery

Organic Vapor Analyzer

Parts Per Million

2

4

8

15

30

30

Very Soft

Soft

Firm

Stiff

Very Stiff

Hard

0

2

4

8

15

0

0.125

0.25

0.5

1.0

-

-

-

-

-

>

0.125

0.25

0.5

1.0

2.0

2.0

0

5

10

20

5

10

20

40

40

None

Low

Moderate

Plastic

Highly Plastic

=

=

=

=

=

=

=

=

=

=

=

ABBREVIATIONS

Qam, Qas, Qal

Qat

Qbc

Qt

Qao

Qle

Q-Tu

Ewi

Emi

Mc

EI

Kknm

Kpg

Kau

=

=

=

=

=

=

=

=

=

=

=

=

=

=

Kef

Kbu

Kdr

Kft

Kgt

Kep

Kek

Kes

Kew

Kgr

Kgru

Kgrl

Kh

Quaternary Alluvium

Low Terrace Deposits

Beaumont Formation

Fluviatile Terrace Deposits

Seymour Formation

Leona Formation

Uvalde Gravel

Wilcox Formation

Midway Group

Catahoula Formation

Laredo Formation

Navarro Group and MarlbrookMarl

Pecan Gap Chalk

Austin Chalk

=

=

=

=

=

=

=

=

=

=

=

=

=

Eagle Ford Shale

Buda Limestone

Del Rio Clay

Fort Terrett Member

Georgetown Formation

Person Formation

Kainer Formation

Escondido Formation

Walnut Formation

Glen Rose Formation

Upper Glen Rose Formation

Lower Glen Rose Formation

Hensell Sand

B

T

E

X

BTEX

TPH

ND

NA

NR

OVA

ppm

Terms used in this report to describe soils with regard to their consistency or conditions are in general accordance with thediscussion presented in Article 45 of SOILS MECHANICS IN ENGINEERING PRACTICE, Terzaghi and Peck, John Wiley & Sons, Inc.,1967, using the most reliable information available from the field and laboratory investigations. Terms used for describing soilsaccording to their texture or grain size distribution are in accordance with the UNIFIED SOIL CLASSIFICATION SYSTEM, as describedin American Society for Testing and Materials D2487-06 and D2488-00, Volume 04.08, Soil and Rock; Dimension Stone;Geosynthetics; 2005.

The depths shown on the boring logs are not exact, and have been estimated to the nearest half-foot. Depth measurements maybe presented in a manner that implies greater precision in depth measurement, i.e 6.71 meters. The reader should understandand interpret this information only within the stated half-foot tolerance on depth measurements.

FIGURE 10bREVISED 04/2012


KEY TO TERMS AND SYMBOLS (CONT'D)

TERMINOLOGY

SOIL STRUCTURE

SAMPLING METHODS

Having planes of weakness that appear slick and glossy.Containing shrinkage or relief cracks, often filled with fine sand or silt; usually more or less vertical.Inclusion of material of different texture that is smaller than the diameter of the sample.Inclusion less than 1/8 inch thick extending through the sample.Inclusion 1/8 inch to 3 inches thick extending through the sample.Inclusion greater than 3 inches thick extending through the sample.Soil sample composed of alternating partings or seams of different soil type.Soil sample composed of alternating layers of different soil type.Soil sample composed of pockets of different soil type and layered or laminated structure is not evident.Having appreciable quantities of carbonate.Having more than 50% carbonate content.

SlickensidedFissuredPocketPartingSeamLayerLaminatedInterlayeredIntermixedCalcareousCarbonate

RELATIVELY UNDISTURBED SAMPLING

NOTE: To avoid damage to sampling tools, driving is limited to 50 blows during or after seating interval.

STANDARD PENETRATION TEST (SPT)

Cohesive soil samples are to be collected using three-inch thin-walled tubes in general accordance with the Standard Practicefor Thin-Walled Tube Sampling of Soils (ASTM D1587) and granular soil samples are to be collected using two-inch split-barrelsamplers in general accordance with the Standard Method for Penetration Test and Split-Barrel Sampling of Soils (ASTMD1586). Cohesive soil samples may be extruded on-site when appropriate handling and storage techniques maintain sampleintegrity and moisture content.

Description

25 blows drove sampler 12 inches, after initial 6 inches of seating.50 blows drove sampler 7 inches, after initial 6 inches of seating.50 blows drove sampler 3 inches during initial 6-inch seating interval.

Blows Per Foot

2550/7"Ref/3"

FIGURE 10c

A 2-in.-OD, 1-3/8-in.-ID split spoon sampler is driven 1.5 ft into undisturbed soil with a 140-pound hammer free falling 30 in.After the sampler is seated 6 in. into undisturbed soil, the number of blows required to drive the sampler the last 12 in. is theStandard Penetration Resistance or "N" value, which is recorded as blows per foot as described below.

REVISED 04/2012

SPLIT-BARREL SAMPLER DRIVING RECORD

TP-30121-01 0.0 to 1.5 12 15

2.0 to 4.0 12 112 2.44 UC

4.5 to 6.0 21 22 46 21 25

6.0 to 8.0 22 48 2.00 PP

8.5 to 10.0 27 22

13.0 to 15.0 26 80 28 52 2.25 PP

18.5 to 20.0 21 17

23.0 to 25.0 23 2.25 PP

CE-30121-01 0.0 to 1.5 14 14

2.5 to 4.0 23 15 72 21 51

4.0 to 6.0 20 103 3.31 UC

6.5 to 8.0 24 32

8.0 to 10.0 30 2.25 PP

13.5 to 15.0 27 20 62 20 42

18.0 to 20.0 9 2.25 PP

23.5 to 25.0 27 25

CE-30121-02 0.0 to 1.5 11 15

2.5 to 4.0 13 18

4.0 to 6.0 18 48 25 23 2.25 PP

6.5 to 8.0 41 19

8.0 to 10.0 18 103 2.16 UC

13.5 to 15.0 19 35 102 37 65

18.0 to 20.0 29 2.25 PP

23.5 to 25.0 34 23

BP-30121-01 0.0 to 1.5 9 15

2.0 to 4.0 15 112 3.18 UC

4.5 to 6.0 23 66 28 38

6.0 to 8.0 22 96 0.63 UC

8.5 to 10.0 41 23

13.0 to 15.0 24 63 27 36 99 1.80 UC

18.5 to 20.0 30 32

23.0 to 25.0 14 113 2.26 UC

T-30121-01 0.0 to 1.5 9 14

2.0 to 4.0 19 72 19 53 103 1.68 UC

4.5 to 6.0 13 20

6.0 to 8.0 18 110 2.10 UC

8.5 to 10.0 29 18

10.0 to 12.0

13.0 to 15.0 22 53 27 26 CH 100 94 2.25 PP

PlasticityIndex

LiquidLimit

PP = Pocket Penetrometer TV = Torvane UC = Unconfined Compression FV = Field Vane

PlasticLimit

WaterContent

(%)

Dry UnitWeight

(pcf)

PROJECT NAME:

FILE NAME: IPS#1.GPJ

USCS % -200Sieve

ShearStrength

(tsf)

StrengthTest

BoringNo.

9/6/2016

UU = Unconsolidated Undrained Triaxial

SampleDepth

(ft)

CU = Consolidated Undrained Triaxial


RESULTS OF SOIL SAMPLE ANALYSES

Blowsper ft

FIGURE 11a


T-30121-0118.5 to 20.0 33 23

23.0 to 25.0 29 93 0.32 UC

28.5 to 30.0 23 34

33.0 to 35.0 29 88 34 54 CH 90 100 2.25 PP

38.5 to 40.0 46 26

43.0 to 45.0 24 100 3.81 UC

48.5 to 50.0 41 23

T-30121-02 0.0 to 1.5 6 12 52 15 37

2.5 to 4.0 8 19

4.0 to 6.0 22 60 23 37 CH 100 88 2.25 PP

6.5 to 8.0 40 20

8.0 to 10.0 23 101 1.50 UC

13.5 to 14.9 50/11" 17

18.0 to 20.0 26 2.25 PP

23.5 to 25.0 33 26

28.0 to 30.0 29 90 1.12 UC

T-30121-03 0.0 to 1.5 6 16

2.5 to 4.0 8 21

4.0 to 6.0 22 65 26 39 2.25 PP

6.5 to 8.0 33 21

8.0 to 10.0 18 109 1.37 UC

13.5 to 14.7 50/8" 14

18.0 to 20.0 17 2.25 PP

23.5 to 25.0 50 17

28.5 to 30.0 26

T-30121-04 0.0 to 1.5 8 14

2.0 to 4.0 18 66 18 48 103 2.10 UC

4.5 to 6.0 20 22

6.0 to 8.0 24 100 1.79 UC

8.5 to 10.0 46 15 48 21 27

13.0 to 15.0 25 94 0.36 UC

18.5 to 19.8 50/10" 18

23.0 to 25.0 26 65 30 35 CH 96 100 2.25 PP

28.5 to 30.0 36

PlasticityIndex

LiquidLimit

PP = Pocket Penetrometer TV = Torvane UC = Unconfined Compression FV = Field Vane

PlasticLimit

WaterContent

(%)

Dry UnitWeight

(pcf)

PROJECT NAME:

FILE NAME: IPS#1.GPJ

USCS % -200Sieve

ShearStrength

(tsf)

StrengthTest

BoringNo.

9/6/2016

UU = Unconsolidated Undrained Triaxial

SampleDepth

(ft)

CU = Consolidated Undrained Triaxial


RESULTS OF SOIL SAMPLE ANALYSES

Blowsper ft

FIGURE 11b


CONSOLIDATION TEST REPORT

Coefficients of Consolidation and Secondary Consolidation

No.Load(tsf)

Cv(ft.2/day)

Ca No.Load(tsf)

Cv(ft.2/day)

Ca No.Load(tsf)

Cv(ft.2/day)

Ca

2 4.00 0.986

3 8.00 1.006

4 16.00 0.013

5 32.00 0.022

6 8.00 0.005

7 4.00 0.004

Vo

id R

atio

0.49

0.51

0.53

0.55

0.57

0.59

0.61

0.63

0.65

0.67

0.69

Applied Pressure - tsf1 10

Natural Dry Dens.LL PI Cr

OverburdenPc CcInitial Void

Saturation Moisture (pcf) (tsf)(tsf) Ratio

89.9 % 22.0 % 100.4 0.090.317.5 0.17 0.647

CLAY, Tan and Gray with ferric staining

Pape-Dawson Engineers

ASTM D2435estimated specific gravityWeight added to prevent swell afterinundation= 2.405 tsf

MATERIAL DESCRIPTION USCS AASHTO

Project No. ASA15-051-00 Client: Remarks:

Project: Vista Ridge Pipeline/Reg. Supply

Location: Boring T-30121-02 Sample 4 4-6ft Depth: 4-6ft Sample Number: 4

RABA KISTNER CONSULTANTS, INC.Figure 12a

60 37

CH



No.Load(tsf)

Cv(ft.2/day)

Ca No.Load(tsf)

Cv(ft.2/day)

Ca No.Load(tsf)

Cv(ft.2/day)

Ca

2 4.00 0.466

3 8.00 0.459

4 16.00 0.260

5 32.00 0.695

6 8.00 0.395

7 4.00 0.357

Vo

id R

atio

0.540

0.555

0.570

0.585

0.600

0.615

0.630

0.645

0.660

0.675

0.690





88.8 % 22.0 % 99.9 0.040.8510.1 0.15 0.656

CLAY, Tan and Gray, with ferric staining




Remarks:Project No. ASA15-051-00 Client:


Loc.: Boring T-30121-01 Sample 11 13-15ft Depth: 13-15ft Sample No.: 11

RABA KISTNER CONSULTANTS, INC.Figure 12b

53 26

CH



No.Load(tsf)

Cv(ft.2/day)

Ca No.Load(tsf)

Cv(ft.2/day)

Ca No.Load(tsf)

Cv(ft.2/day)

Ca

2 2.00 1.021

3 4.00 0.493

4 8.00 0.416

5 16.00 0.162

6 32.00 0.078

7 8.00 0.059

8 2.00 0.031

Vo

id R

atio

0.600

0.615

0.630

0.645

0.660

0.675

0.690

0.705

0.720

0.735

0.750





92.6 % 25.6 % 95.5 0.041.447.1 0.15 0.733

CLAY, Tan and Gray







RABA KISTNER CONSULTANTS, INC.Figure 12c

CH

65 35



No.Load(tsf)

Cv(ft.2/day)

Ca No.Load(tsf)

Cv(ft.2/day)

Ca No.Load(tsf)

Cv(ft.2/day)

Ca

2 4.00 0.148

3 8.00 0.068

4 16.00 0.021

5 32.00 0.020

6 8.00 0.014

7 4.00 0.006

Vo

id R

atio

0.705

0.720

0.735

0.750

0.765

0.780

0.795

0.810

0.825

0.840

0.855





92.4 % 29.2 % 90.1 0.071.987.6 0.17 0.836

CLAY, Dark Gray, with lignite deposits







RABA KISTNER CONSULTANTS, INC.Figure 12d

CH

5488

Project Number: ASA15-051-00

Test Date:

Type No. of

of Blows Incre. Cumm. MR qult

Ham. (mm) (in) (%) (ksi) (ksf)

1 1 51 2 4 6 1.37

1 1 45 3.8 4 6 1.37

1 1 33 5.1 6 9 1.80

1 1 44 6.8 4 6 1.37

1 1 42 8.5 4 6 1.37

1 1 20 9.3 10 15 2.52

1 2 59 11.6 7 10.5 1.99

1 2 31 12.8 14 21 3.15

1 2 45 14.6 9 13.5 2.35

1 2 59 16.9 7 10.5 1.99

1 2 58 19.2 7 10.5 1.99

1 1 51 21.2 4 6 1.37

1 1 50 23.1 4 6 1.37

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

NOTES: Hammer 17.6 lbs = 1 Hammer 10.1 lbs = 2

Figure 13a

Vista Ridge - Regional Supply Project, IPS No. 1

Bastrop County, Texas

Penetration

CBR

August 11, 2016

DCP TEST DATA DCP-1

0

20

40

60

80

100

0

5

10

15

20

25

30

35

40

451.00 10.00 100.00

DE

PT

H, cm

.

DE

PT

H, in

.CBR

0

20

40

60

80

100

0

5

10

15

20

25

30

35

40

450.00 10.00 20.00 30.00

DE

PT

H, cm

.

DE

PT

H, in

.

MR, ksi

0

20

40

60

80

100

0

5

10

15

20

25

30

35

40

450.00 5.00 10.00

DE

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Test Date:

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1 1 26 1 8 12 2.17

1 2 29 2.2 15 22.5 3.30

1 2 32 3.4 13 19.5 3.00

1 3 40 5 16 24 3.44

1 3 35 6.4 19 28.5 3.86

1 3 32 7.6 21 31.5 4.13

1 3 32 8.9 21 31.5 4.13

1 3 31 10.1 21 31.5 4.13

1 3 30 11.3 22 33 4.25

1 3 34 12.6 19 28.5 3.86

1 3 30 13.8 22 33 4.25

1 3 28 14.9 24 36 4.51

1 3 40 16.5 16 24 3.44

1 3 28 17.6 24 36 4.51

1 3 35 19 19 28.5 3.86

1 3 40 20.6 16 24 3.44

1 3 38 22 17 25.5 3.59

1 3 42 23.7 15 22.5 3.30

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Figure 13b


Penetration

CBR

August 11, 2016

DCP TEST DATA DCP-2


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1 2 35 1.4 12 18 2.84

1 6 50 3.3 27 40.5 4.87

1 5 39 4.9 29 43.5 5.11

1 3 24 5.8 28 42 4.99

1 3 27 6.9 25 37.5 4.63

1 4 40 8.5 22 33 4.25

1 3 34 9.8 19 28.5 3.86

1 3 36 11.2 18 27 3.72

1 3 38 12.7 17 25.5 3.59

1 5 51 14.7 22 33 4.25

1 4 40 16.3 22 33 4.25

1 6 60 18.7 22 33 4.25

1 3 31 19.9 21 31.5 4.13

1 3 38 21.4 17 25.5 3.59

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Figure 13c


Penetration

CBR

August 11, 2016

DCP TEST DATA DCP-3


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451.00 10.00 100.00

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450.00 20.00 40.00 60.00

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.


Geotechnical-Engineering Report

Geotechnical Services Are Performed for Specific Purposes, Persons, and ProjectsGeotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical-engineering study conducted for a civil engineer may not fulfill the needs of a constructor — a construction contractor — or even another civil engineer. Because each geotechnical- engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. No one except you should rely on this geotechnical-engineering report without first conferring with the geotechnical engineer who prepared it. And no one — not even you — should apply this report for any purpose or project except the one originally contemplated.

Read the Full ReportSerious problems have occurred because those relying on a geotechnical-engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only.

Geotechnical Engineers Base Each Report on a Unique Set of Project-Specific FactorsGeotechnical engineers consider many unique, project-specific factors when establishing the scope of a study. Typical factors include: the client’s goals, objectives, and risk-management preferences; the general nature of the structure involved, its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engineer who conducted the study specifically indicates otherwise, do not rely on a geotechnical-engineering report that was:• not prepared for you;• not prepared for your project;• not prepared for the specific site explored; or• completed before important project changes were made.

Typical changes that can erode the reliability of an existing geotechnical-engineering report include those that affect: • the function of the proposed structure, as when it’s changed

from a parking garage to an office building, or from a light-industrial plant to a refrigerated warehouse;

• the elevation, configuration, location, orientation, or weight of the proposed structure;

• the composition of the design team; or• project ownership.

As a general rule, always inform your geotechnical engineer of project changes—even minor ones—and request an

assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed.

Subsurface Conditions Can ChangeA geotechnical-engineering report is based on conditions that existed at the time the geotechnical engineer performed the study. Do not rely on a geotechnical-engineering report whose adequacy may have been affected by: the passage of time; man-made events, such as construction on or adjacent to the site; or natural events, such as floods, droughts, earthquakes, or groundwater fluctuations. Contact the geotechnical engineer before applying this report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems.

Most Geotechnical Findings Are Professional OpinionsSite exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engineers review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ — sometimes significantly — from those indicated in your report. Retaining the geotechnical engineer who developed your report to provide geotechnical-construction observation is the most effective method of managing the risks associated with unanticipated conditions.

A Report’s Recommendations Are Not FinalDo not overrely on the confirmation-dependent recommendations included in your report. Confirmation-dependent recommendations are not final, because geotechnical engineers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engineer who developed your report cannot assume responsibility or liability for the report’s confirmation-dependent recommendations if that engineer does not perform the geotechnical-construction observation required to confirm the recommendations’ applicability.

A Geotechnical-Engineering Report Is Subject to MisinterpretationOther design-team members’ misinterpretation of geotechnical-engineering reports has resulted in costly

Important Information about This

Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.

While you cannot eliminate all such risks, you can manage them. The following information is provided to help.

problems. Confront that risk by having your geo technical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review pertinent elements of the design team’s plans and specifications. Constructors can also misinterpret a geotechnical-engineering report. Confront that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing geotechnical construction observation.

Do Not Redraw the Engineer’s LogsGeotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical-engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk.

Give Constructors a Complete Report and GuidanceSome owners and design professionals mistakenly believe they can make constructors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give constructors the complete geotechnical-engineering report, but preface it with a clearly written letter of transmittal. In that letter, advise constructors that the report was not prepared for purposes of bid development and that the report’s accuracy is limited; encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure constructors have sufficient time to perform additional study. Only then might you be in a position to give constructors the best information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions.

Read Responsibility Provisions CloselySome clients, design professionals, and constructors fail to recognize that geotechnical engineering is far less exact than other engineering disciplines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled “limitations,” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help

others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly.

Environmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical study. For that reason, a geotechnical-engineering report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk-management guidance. Do not rely on an environmental report prepared for someone else.

Obtain Professional Assistance To Deal with MoldDiverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional mold-prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, many mold- prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical- engineering study whose findings are conveyed in this report, the geotechnical engineer in charge of this project is not a mold prevention consultant; none of the services performed in connection with the geotechnical engineer’s study were designed or conducted for the purpose of mold prevention. Proper implementation of the recommendations conveyed in this report will not of itself be sufficient to prevent mold from growing in or on the structure involved.

Rely, on Your GBC-Member Geotechnical Engineer for Additional AssistanceMembership in the Geotechnical Business Council of the Geoprofessional Business Association exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project. Confer with you GBC-Member geotechnical engineer for more information.

8811 Colesville Road/Suite G106, Silver Spring, MD 20910Telephone: 301/565-2733 Facsimile: 301/589-2017

e-mail: [email protected] www.geoprofessional.org

Copyright 2015 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, or its contents, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document

is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document as a complement to or as an element of a geotechnical-engineering report. Any other firm, individual, or other entity that so uses this document without

being a GBA member could be commiting negligent or intentional (fraudulent) misrepresentation.

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