R - 163-428 Geotechnical Report.pdf

GEOTECHNICAL ENGINEERING EXPLORATION REPORT

PROPOSED WATER TANK

CONTINGENCY WATER SUPPLY & REMEDIATION

RICHARD L. ROUDEBUSH VA MEDICAL CENTER

1481 W. 10TH STREET

INDIANAPOLIS, INDIANA

Prepared for:

CMET ENGINEERING, LLC

Prepared by:

CIVIL & ENVIRONMENTAL CONSULTANTS, INC.

CINCINNATI, OHIO

CEC Project 163-428

February 7, 2018

-i- CEC Project 163-428

TABLE OF CONTENTS

Page

1.0 INTRODUCTION

1.1 PURPOSE

1.2 SCOPE OF SERVICES

1.3 STANDARD OF CARE

2.0 PROJECT INFORMATION

3.0 FIELD EXPLORATIONS AND LABORATORY TESTING

3.1 FIELD EXPLORATIONS

3.2 LABORATORY TESTING

4.0 EXPLORATORY FINDINGS

4.1 Asphalt Pavement Section

4.2 Existing Fill

4.3 Natural Alluvium

4.4 Glacial Outwash

4.5 Bedrock

4.6 Groundwater

5.0 CONCLUSIONS

5.1 GENERAL PROFILE AND GROUNDWATER CONDITIONS

5.2 FOUNDATION CONSIDERATIONS

5.2.1 Axial Load Capacity of the ACIP Concrete Piles

5.2.2 Lateral Load Capacity

5.2.3 Uplift Capacities of the Auger-Cast-In-Place Concrete Piles

6.0 DESIGN AND CONSTRUCTION RECOMMENDATIONS

6.1 SITE DEMOLITION

6.2 TEMPORARY EXCAVATIONS

6.3 STRUCTURE FOUNDATIONS

6.4 ENGINEERED FILL AND SUBGRADE PREPARATION

6.5 GROUNDWATER IMPACT

6.6 SEISMICITY

7.0 CONSTRUCTION QUALITY CONTROL MEASURES

8.0 BASIS FOR RECOMMENDATIONS

9.0 CONSTRUCTION PLANS AND SPECIFICATION REVIEW

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LIST OF FIGURES

Figure

Site Location Map Site and Vicinity Aerial Map Boring Location Plan Subsurface Diagram Cross Section A-A’ Summary of Soil Conditions for Axial and Lateral Pile Load Analysis

LIST OF APPENDICES

Appendix

Important Information About This Geotechnical-Engineering Report ................................................ I Geotechnical Exploration Test Boring Logs ....................................................................................... II Laboratory Test Results ..................................................................................................................... III

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1.0 INTRODUCTION

1.1 PURPOSE

The purpose of this report is to present the findings of the geotechnical engineering explorations performed for the subject project site in order to characterize the subsurface soil and groundwater conditions within general footprint of the proposed water supply tank, to perform engineering analyses, and to develop geotechnical engineering design and construction recommendations for earthwork and the foundations of the water tank.

1.2 SCOPE OF SERVICES

The scope of services performed by CEC to meet the intended purpose included: a review of published geologic data, collection of soil samples from borings, performance of geotechnical engineering analyses, and development of this summary report. The developed information, conclusions and recommendations contained within this summary report include the following:

• A summary of the project description, including topographic site features;

• A review of our field and laboratory test procedures and the results of testing conducted;

• A review of subsurface conditions with pertinent available physical properties;

• Depths of water levels measured in the borings at the time of the field exploration;

• Identification of subsurface conditions that may impact the design or construction of the planned water supply tank (i.e., presence of loose, weak or compressible fill and natural soil);

• Recommended deep foundation system and associated design criteria;

• A summary of general construction guides for the recommended deep foundation system;

• Recommended Seismic Site Class and site coefficients based on the results of our test borings and site location; and,

• Recommendations for site preparation, including earthwork construction procedures, compaction criteria for engineered fill placement and remediation of unsuitable soil subgrade materials.

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Our conclusions and recommendations contained herein are based on the results of our field explorations, laboratory test results from selected soil samples and geotechnical engineering analyses. The results of the field explorations and laboratory test data, which form the basis of our recommendations, are presented in the Appendices.

This report has been prepared for CMET Engineering, LLC (CMET) and their design consultants to be used solely in evaluating the soils underlying the footprint of the water supply tank and presenting geotechnical engineering design and construction recommendations specific to the subject project. This Report of Geotechnical Engineering Exploration has not been prepared for use by other parties, and may not contain sufficient information for purposes of other parties nor other uses.

The assessment of general site environmental conditions or the presence of pollutants in the soil, rock and groundwater of the site was beyond the scope of this geotechnical exploration.

1.3 STANDARD OF CARE

The geotechnical engineering services performed by CEC were conducted in a manner consistent with the level of care and skill ordinarily exercised by members of the geotechnical engineering profession practicing contemporaneously under similar conditions in the locality of the project. No other warranty, express or implied, is made. Appendix I contains a document entitled "Important

Information About This Geotechnical-Engineering Report." This document further explains the realities of geotechnical engineering and the limitations that exist in evaluating geotechnical issues.

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2.0 PROJECT INFORMATION

It is understood that the Department of Veterans Affairs (VA) requested a feasibility study to determine the need for a contingency water supply for the existing Richard L. Roudebush VA

Medical Center (VAMC) facility located at 1481 W. 10th Street in Indianapolis, Marion County, Indiana. The approximate location of the subject facility is depicted on the enclosed Site Location

Map (Figure 1). In connection with this request, a joint feasibility study was conducted by CMET and CEC to determine whether water supply improvements are necessary for the VAMC facility to comply with the VA domestic water requirements. The results of this feasibility study are presented in a report titled “Contingency Water Supply and Remediation Feasibility Study”

(Feasibility Study), dated October 27, 2017. Based on the findings of the Feasibility Study, the project requires the installation of a 456,167-gallon capacity contingency water supply. However, based on industry standard for the construction of large water storage tanks, a 500,000-gallon storage water tank is understood to have been selected for this project.

According to the Feasibility Study, there are six access points to the VAMC property: 1) three driveways off St. Margaret’s Drive, and, 2) three driveways off N. Porto Alegre Street. Access driveways consist of curb-cut ingress and egress drive aprons. Vehicular parking on the property is provided by nine surface parking lots, one six-story precast concrete parking garage, and one underground two-level parking garage. It is our understanding that the proposed water tank will be located within the southern portion of Lot-H and designated as Alternate 1A within the referenced Feasibility Study. Specifically, the tank will be situated within the southeast quadrant of Lot H adjacent to the existing parking garage structure. The existing buildings and the parking areas together with the proposed footprint of the water supply tank are shown on the Site And

Vicinity Aerial Map (Figure 2). As shown on this figure, Lot-H is located in the southwest corner of the subject property, east of Porto Alegre Street, north of west Michigan Street, west of the 6-story parking garage, and south of Dr. Harvey Middleton Way 1.

Based on the existing site and topographic information presented on the recent ALTA/NSPS Land

Survey prepared by CEC dated January 15, 2018, the site in or within the proximity of the tank is underlain by several existing underground utilities which include: 1) a 12-inch diameter sanitary

-4- CEC Project 163-428 sewer that traverses north to south along the east side of Lot H; 2) an 8-inch diameter water line traversing northwest to southeast; 3) several storm sewer alignments and catch basins; and,

4) several electric lines. Based on the referenced survey, the existing ground surface within Lot H is relatively flat with a ground surface elevation between about 701 to 703 feet above mean sea level (amsl).

The proposed water supply tank will consist of an approximate 500,000 gallon capacity, 153.5 feet tall Waterspheroid Elevated Water Storage Tank with a circular footprint of approximately 30 feet in diameter and a bell diameter of about 28 feet. The proposed grading was not available at the time of this report; however, it is anticipated that there will not be a significant grade change between the existing and proposed grades.

At this time, the foundation design for the proposed water tank is preliminary. It is our understanding; however, that the proposed water supply tank will be supported on a ring-shaped foundation that is approximately 3 feet thick and bearing at a depth of about 4 feet below exterior grades. The inner and outer diameter of the ring foundation will be 25 and 31 feet, respectively, corresponding to a 6-foot wide contact surface. Based on information from the tank manufacture, the dead weight of the tank when full will be contributed by about 4,235,000 pounds (lbs.) of water along with the weight of the tank which is 427,000 lbs. combining for a total dead weight of about

4,662,000 lbs. or about 2,331 tons. Given the width of the planned ring foundation, it is estimated that the contact pressure at the bottom of the proposed ring foundation will be in excess of 16,000 pounds per square foot (psf). However; it is anticipated that the foundation of the proposed water tank structure will also be subjected to lateral loads or overturning moments generated by seismic or wind loads which could increase the estimated bearing pressure. At this time, the magnitude of this additional eccentric loading to be exerted to the foundations by the seismic and the wind loads has not yet been quantified by the Structural Engineer; and therefore, the maximum bearing pressure of the structure is unknown at this time.

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3.0 FIELD EXPLORATIONS AND LABORATORY TESTING

3.1 FIELD EXPLORATIONS

The soil and groundwater conditions at the site were explored by drilling two test borings

(designated as Borings B-1 and B-2). The test boring locations were selected by CEC for the purpose of evaluating the subsurface soil and groundwater conditions within the footprint of the proposed water supply tank per the location identified as Alternative 1A within the referenced

Feasibility Study. Each boring location and associated ground surface elevation was surveyed in the field by CEC. The individual test boring logs (included within Appendix II) include the established boring coordinate location (based on Indiana State Plane West NAD83) and corresponding ground surface elevation. The approximate location of the test borings are depicted on Figure 3 (Boring Location Plan) enclosed within this report.

The boring program was performed between December 20 and 21, 2017. Earth Exploration, Inc.

was subcontracted by CEC to perform the drilling services using a truck mounted drill rig. Each boring was advanced using 3.25-inch inner diameter hollow-stem augers to advance the borings to the termination depths that varied from approximately 68.6 to 95.6 feet below the ground surface

(bgs). As each boring was advanced through soil, disturbed soil samples were obtained at selected depths. The disturbed soil samples were generally obtained at 2.5-foot intervals to a depth of

10 feet bgs, and then at 5 foot centers thereafter using a split-spoon sampler in accordance with the Standard Penetration Test (SPT) (ASTM D-1586). The SPT sampling consisted of driving a

2-inch outer diameter split barrel sampler using a 140-pound hammer freely falling a distance of

30 inches. The number of blows required to drive the sampler over three successive 6-inch increments was recorded. The first 6-inch increment was considered to be a seating interval and was not used to estimate soil conditions. The sum of the blows for the second and third driving increments was considered to be the SPT value or “N” value of the soil. The N value was used to estimate the relative density of coarse-grained soil or the consistency of fine-grained soil. The soil samples obtained from the exploration program were visually observed in the field by the CEC field representative and preserved for review by the Geotechnical Engineer and potential laboratory testing. In addition to SPT sampling, CEC field personnel obtained two relatively

-6- CEC Project 163-428 undisturbed soil samples from Boring B-2 using a 3-inch outside diameter Shelby Tube sampler

(in accordance with ASTM D-1587).

Groundwater level measurements were obtained both during and after the completion of drilling operations. However, the addition of bentonite slurry into the hollow stem augers to combat heaving conditions in Boring B-1 may have affected the accuracy of groundwater level measurement after completion of the drilling procedures. Subsequent to drilling completion and obtaining final groundwater level readings, the borings were backfilled with auger cuttings and capped with asphalt patch. The groundwater level measurements are included on the individual boring logs.

The field exploration program was coordinated and supervised by a CEC Geotechnical Engineer.

A CEC field representative observed the drilling operations and performed the following specific duties as directed by the Geotechnical Engineer: 1) reviewed soil samples recovered from the borings; 2) described the soil color, texture, apparent origin and apparent relative moisture content of the SPT samples obtained; 3) preserved representative portions of the soil samples; 4) prepared a field log of each boring; 5) made seepage and groundwater observations; and, 6) estimated unconfined shear strength values on specimens exhibiting cohesion (using a hand-penetrometer).

The field logs were reviewed and modified by the CEC Geotechnical Engineer, if needed, based on a review of the developed field information and soil samples. The final boring logs are included in Appendix II. Appendix II also contains a summary of the definitions for standard terms and symbols used in the boring logs.

3.2 LABORATORY TESTING

Prior to shipment to the laboratory, the soil samples were visually reviewed by CEC’s

Geotechnical Engineer to aid in the evaluation of the engineering properties of the subsurface soil.

The information was used to modify the soil descriptions contained on the field logs where necessary. In addition, representative samples were selected for laboratory testing. The laboratory program, performed by Consulting Services, Inc., included natural moisture content determinations, Atterberg Limits, particle size analyses, and an Unconsolidated Undrained

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Triaxial Compression test. The laboratory testing was performed in general accordance with applicable ASTM specifications. The individual laboratory data sheets and results are included in

Appendix III. The information developed from visual review of the soil samples and the laboratory testing was used to modify the soil descriptions contained on the field logs where necessary. The final boring logs, enclosed in Appendix II, include the developed field data and select laboratory results (moisture content, Atterberg Limits, and grain size test results) in graphical form.

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4.0 EXPLORATORY FINDINGS

The subsurface soil conditions encountered during CEC’s explorations are described on each test boring log presented in Appendix II. These logs represent CEC’s interpretation of the subsurface conditions encountered at each boring location based on our site observations, field logs prepared by CEC’s field representative, visual review of the soil samples by the Geotechnical Engineer, and the laboratory test results. The lines designating the interface between various soil strata on the boring logs represent the approximate interface location; however, the actual transition between strata may be gradual and indistinct. The subsurface soil and groundwater characterizations included herein, including summary test data, are based on the subsurface findings from the geotechnical explorations performed by CEC between December 20 and 21, 2017.

In addition to the individual boring logs, a Subsurface Diagram has been prepared (Figure 4) which is based on Cross Section A-A’, as depicted on the Boring Location Plan (Figure 3). This

Subsurface Diagram includes a graphical interpretation of the soil and bedrock strata identified by the selected borings along the selected cross section, representative boring data (i.e., N-values, Hand Penetrometer readings and groundwater levels), current ground surface elevation, limits of the proposed water supply tank and a general interpretation of the soil strata between the borings.

In general, the subsurface soil profile consists of an approximate 12-inch thick asphalt pavement section (including the aggregate base) overlying a layer of existing fill that is underlain by natural alluvial and glacial outwash soils. The previously placed fill soil is present to a depth of about 13.5 to 13.8 feet bgs and is considered variable with respect to soil type, density, composition and strength. An alluvial deposit comprised of relatively loose sand was encountered below the existing fill stratum in both of the test borings and extended to a depth of about 24 feet bgs. Typical of a glaciated area, an outwash deposit, consisting of relatively compact and dense sand and gravel mixtures, was encountered below the alluvial sand deposit. In Boring B-1, the glacial outwash deposit is underlain by limestone, which was encountered at a depth of approximately 95.5 feet bgs. Groundwater was encountered between depths of approximately 27 to 28 feet bgs

(i.e., between approximate elevations 674.0 and 675.0 feet amsl). The following sections present a more detailed description of the subsurface conditions encountered in the two explorations.

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4.1 Asphalt Pavement Section

Asphalt pavement was present at the ground surface in each of the two borings. Specifically, the asphalt pavement in Borings B-1 and B-2 was noted to be approximately 6 and 3 inches in thickness, and the aggregate base beneath the asphalt pavement is approximately 6 inches and

9 inches in thickness, respectively.

4.2 Existing Fill

Soil visually identified as fill was encountered in each of the two borings. The fill soil, present below the asphalt pavement section, extends to a depth of about 13.5 to 13.8 feet bgs. (elevations between about 687.9 and 688.8 feet amsl) in Borings B-1 and B-2, respectively. The fill materials are variable and are described as low plasticity sandy clay and silty clay or non-plastic sand, clayey sand and silty sand. The fill contains variable amounts of gravel and rock fragments, as well as, notable amounts of brick, concrete and glass fragments at isolated depths and locations. With respect to consistency and relative density, the fill soils are considered variable as indicated by descriptions ranging from medium stiff to very stiff and very loose to medium dense, corresponding to N values ranging from 2 to 32 blows per foot (bpf). Unconfined compressive strength values (estimated by means of a Hand-Penetrometer) for the cohesive fill soil ranged from

2.25 to in excess of 4.5 tons per square foot (tsf). In general, the fill stratum data with respect to density, composition and compaction is variable.

Based on an Atterberg Limits test performed on a sample of the fill obtained from Boring B-1 (3.5 to 5 feet bgs), the liquid and plastic limit values were 26 and 20 percent, respectively. The moisture contents of selected fill soil samples ranged from 11 to 21 percent. In addition, a laboratory triaxial unconsolidated undrained shear strength test was performed on a relatively undisturbed Shelby

Tube sample obtained from Boring B-2 between a depth of about 6 and 8 feet bgs that yielded a shear strength value of 6,750 psf. The gradation characteristics of the fill soils are reflected by three grain-size curves obtained from tests conducted on Sample S-1 in Boring B-1 and on Samples

S-1 and S-3 in Boring B-2. The grain size curves are included in Appendix III.

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4.3 Natural Alluvium

River valley soil deposits, identified as alluvium, were encountered underlying the existing fills soils at depths between about 13.5 and 13.8 feet bgs (between elevations about 687.9 and 688.8 feet amsl) in Borings B-2 and B-1, respectively. In general, the natural alluvial deposit was relatively granular in nature consisting of fine sand. In Borings B-1 and B-2, the granular alluvial deposit extends to depths of about 23.8 feet and 24.0 feet bgs (about elevations 678.5 and 677.7 feet), respectively, then transitions into a glacial outwash deposit. Regarding relative density, the alluvial soils are generally described as loose with corresponding N values generally varying between 5 and 9 bpf. The gradation characteristics of the alluvial soils are reflected by a grain-size curve obtained from a test conducted on Sample S-2 in Boring B-1. The grain size curve is included in

Appendix III.

4.4 Glacial Outwash

A glacial outwash deposit was encountered in each boring underlying the existing alluvial soils at a depth of about 24 feet bgs (elevations between about 677.7 and 678.5 feet amsl) and extended to the boring termination depth of 68.6 feet bgs (elevation 633.1 feet amsl) in Boring B-2 and to the apparent bedrock surface at about 95.5 feet bgs (elevation 606.8 feet amsl) in Boring B-1. The outwash deposits are generally described as sand and gravel with insignificant percentages of silt and clay. With respect to relative density, the outwash deposits are medium dense to very dense with corresponding N values varying from 15 bpf to SPT refusal (where less than 6 inches is achieved for 50 blows).

The gradation characteristics of the glacial outwash soils are reflected by three grain-size curves obtained from tests conducted on Samples S-8, S-12 and S-19 obtained from Boring B-1. The grain size curves are included in Appendix III.

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4.5 Bedrock

Boring B-1 encountered the apparent bedrock surface at a depth of about 95.5 feet bgs (elevation

606.8 feet amsl). Based on the limited recovery obtained from the SPT Sample SS-22, the bedrock is described as gray limestone that is slightly weathered, very broken and hard.

4.6 Groundwater

Groundwater measurements were made in each of the two borings during drilling and at the completion of drilling. In Borings B-1 and B-2, groundwater was first encountered during the drilling operations at depths of approximately 27.0 and 28.0 feet bgs (elevations of 675.3 and 673.7 feet amsl) respectively. However, the boreholes caved at depths of about 19.0 feet (Boring B-2) and 22.5 feet bgs (Boring B-1) as the augers were removed resulting in dry conditions at the completion of drilling. The borehole at Boring B-1 was left open for about 16.5 hours after completion of drilling and was observed to remain dry at the cave depth of about 21.5 feet bgs

(elevation 680.8 feet amsl). It should be recognized that addition of bentonite slurry into the hollow stem augers to combat heaving conditions in the boreholes may have affected the accuracy of groundwater level measurement after completion of the drilling procedures. It should also be noted that groundwater levels at the site are affected by many hydrologic characteristics in the area and may vary from those measured at the time of drilling. The specific groundwater readings are included on the individual boring logs within Appendix II.

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5.0 CONCLUSIONS

5.1 GENERAL PROFILE AND GROUNDWATER CONDITIONS

The subsurface conditions encountered in the explorations performed at the project site revealed that, beneath an approximate 12-inch thick asphalt pavement section, undocumented fill soils are present within the footprint of the proposed water tank. The undocumented fill soils, which are approximately 13 to 14 feet in thickness, are considered variable with respect to density, composition and compaction. The undocumented fill soils are not considered suitable for foundation support. The fill soils are underlain by a compressible alluvial deposit, which is relatively granular in nature and generally consists of loose fine sand. The lower boundary of the alluvial deposit was found to be at a depth of approximately 24 feet bgs. The compressible alluvial soils are also not considered suitable for the support of the proposed tank and/or susceptible to consolidation settlement. The alluvial soils are underlain by deep glacial deposits of sand and gravel identified in this report as glacial outwash. The glacial outwash deposits, which are generally compact, are considered to be favorable for foundation support. Specifically, the relative density of the glacial outwash deposits are generally characterized as medium dense to very dense with corresponding N values varying from 15 bpf to SPT refusal (where less than 6 inches is achieved for 50 blows). Below a depth of about 41 to 43 feet bgs (below an elevation of about

656 feet amsl); however, the relative density description for the outwash deposits is very dense with corresponding N values in excess to 30 bpf or SPT refusal. Beneath the outwash deposit is bedrock described as gray slightly weathered limestone. The surface of the bedrock is at a depth of approximately 95 feet bgs. Per the findings of the test borings, it is concluded that the surface of the groundwater at the project site is below a depth of approximately 27 feet bgs, (i.e., below elevation of 675 feet amsl).

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5.2 FOUNDATION CONSIDERATIONS

Overall, it is CEC’s opinion that the subsurface conditions within the limits of the proposed water supply tank are suitable for the proposed construction provided that the proposed structure is supported on a deep foundation system. Specifically, CEC performed foundation bearing and settlement analyses using the results of our field and laboratory explorations and the provided structure details. On this basis, it is CEC’s opinion that foundation loads for the proposed water tank structure will be too heavy and the near-surface soils within the top approximate 24 feet of the subsurface soil profile are too weak and settlement sensitive for shallow foundation alternatives. Therefore, a deep foundation system that penetrates through the fill and the loose alluvial soils and sufficiently founded in the glacial outwash deposit needs to be implemented for support of the water tank structure.

CEC analyzed several types of deep foundations, which may be considered feasible from an engineering standpoint, for support of the water tank. Specifically, driven piles or bored piles such as auger-cast-in-place concrete (ACIP) piles were considered as possible deep foundation solutions. Based on past experience, it is CEC’s opinion that an ACIP pile scheme will be a more economical foundation system compared to driven piles.

ACIP piles are installed by first augering to the design tip elevation or bearing stratum with a continuous flight hollow-stem auger of the appropriate diameter. Then, as the auger is slowly withdrawn from the ground, a high strength cement grout is pumped under high pressure through the hollow-stem auger, resulting in a continuous column of high strength cement grout formed from the auger tip elevation to the ground surface. Pile reinforcement (i.e., cages or bars) is included as needed to satisfy the requirements of Section 1810 of the International Building Code

(IBC 2012). Cages or bars are generally inserted into the fluid grout column with centering devices to assure that the reinforcement is installed to within structural tolerances. The ACIP piles may be grouped in clusters to support the proposed foundation loads based on the anticipated live and dead loads and applying the appropriate structural reduction factors. A pile load test is generally performed prior to production pile installation in order to verify the selected pile capacity and load-settlement characteristics of the piles. Due to nature of the ACIP pile installation process, the grout

-14- CEC Project 163-428 column can be compromised and impact the integrity of the pile. On this basis, site inspection and pile integrity testing are considered integral components of the ACIP pile installation.

5.2.1 Axial Load Capacity of the ACIP Concrete Piles

CEC performed axial pile capacity computations for various sizes of ACIP piles extended to bear within the glacial outwash deposit. The pile analysis were performed per FHWA-HIF-07-03

Design Manual titled “Geotechnical Engineering Circular No.8 – Design and Construction of

Continuous Flight Auger (CFA) Piles”. A factor of safety (FS) of 2 was used for side shear and for end bearing in the analyses. CEC concludes that 12 – 14 - and 16-inch diameter ACIP piles having a minimum tip elevation of 644.0 feet amsl may be designed for an allowable axial load of

75, 90 and 108 tons per pile, respectively. In case the piles are extended to a tip elevation of 639.0 feet amsl, the same diameter piles may be designed for an allowable axial load of 85, 105 and 120 tons per pile, respectively. Based on our static analyses, the piles will derive capacity from a combination of skin friction and end bearing within the glacial outwash deposit. Also based on our analyses, the settlement at the pile tips, under the above mentioned allowable working loads, will be less than 0.5 inches.

Attached to this report is a figure (Figure 5), titled “Summary of Soil Conditions for Axial and

Lateral Pile Load Analysis”, which depicts the soil profile used when estimating the axial load capacities of the piles with different sizes and tip elevations. As shown on this figure, the soil profile considered in the analyses includes a total of six soil types depicted as Soil A through Soil

G. The soil types identified as Soil A through Soil C indicate the relatively cohesive and the loose portions of the fill stratum. As noted earlier the lower boundary of the fill stratum is near elevation

689 feet amsl. The soil type identified as Soil D represents the loose alluvial sand deposit. The lower boundary of this soil type is estimated to be near approximate elevation 679 feet amsl. The soil type identified as Soil F represents the upper portion of the glacial outwash deposit where the stratum is generally medium dense in relative density. The soil type identified as Soil G represents the lower very dense portion of the glacial outwash deposit where the N values exceed 30. As noted previously, the upper boundary of Soil G is near elevation 656 feet amsl. Figure 5 shows

-15- CEC Project 163-428 that beneath the glacial soils is bedrock, which is slightly weathered limestone. The soil properties of the above-referenced soil types used in the analyses are also depicted on this figure.

The ACIP piles may be grouped in clusters to support the proposed loads based on the anticipated live, seismic and dead loads and applying structural reduction factors. No reduction of the individual pile capacity for performance in groups is required provided that the spacing between the piles is equal to at least three times the diameter of the piles. In case the pile spacing within the group of piles is less than three times the diameter of the pile, it may be required that the individual pile capacity be reduced by multiplying the individual pile capacity by a reduction factor to be determined by the project geotechnical engineer.

5.2.2 Lateral Load Capacity

Insofar as the lateral loads on the piles and the pile groups are concerned, they can be resisted by passive pressures against pile caps and passive pressures against the upper parts of the piles below the proposed ring foundation. Passive pressures may be considered against part of pile caps located more than 30 inches below the finish exterior grades within the proximity of the ring foundation.

In case the lateral loads on the ring foundation are such that they cannot be economically resisted against parts of the ring foundation located 30 inches below the finished exterior grades, the proposed piles will then have to be utilized to resist the lateral loads.

If it is required that the proposed lateral loads exerted to the structure by the wind and the seismic loads be partly resisted by the ACIP piles, the assessment of the lateral load capacity of the ACIP piles may then be made using load deflection curves, also known as P-Y curves. It should be noted that the lateral pile capacity of a given pile is highly dependent upon several factors, the most significant of which are: 1) pile head fixity, that is, whether or not the piles are fixed, restrained or free to rotate at the pile head; 2) the stiffness of soils surrounding the upper 10 to 30 feet of the pile (the soil properties that may be used in the lateral pile capacity analyses are shown on Figure

5 titled “Summary of Soil Conditions for Axial and Lateral Pile Load Analysis”; 3) the position of the pile within the pile group; and, 4) the stiffness of the pile (i.e., the reinforcement detail of the

-16- CEC Project 163-428 piles). In connection with this, once the size and the reinforcement details of the ACIP piles are finalized by the structural engineer, CEC can assess the behavior of the on-site soils against various conditions with load deflection curves. This assessment will be made with an “L-Pile Computer

Software”, prepared by Ensoft, Inc.

5.2.3 Uplift Capacities of the Auger-Cast-In-Place Concrete Piles

Insofar as the uplift capacities of the 12-, 14- and 16-inch-diameter ACIP piles at a tip elevation of 644.0 feet amsl are concerned, they may be designed for an allowable individual uplift capacity of 35 tons, 40 tons and 50 tons, respectively. In case the piles are extended to a tip elevation of

639.0 feet amsl, the same diameter piles may be designed for an allowable individual uplift capacity of 45 , 50 and 60 tons per pile, respectively. Similar to the axial pile capacity analyses, the uplift capacities of the piles were performed using the soil profile and the soil properties as shown in Figure 5 attached to this report. The above-referenced FHWA document was used when estimating the uplift capacities of the ACIP piles using a FS value of 3. The top 5 feet of the soil profile was omitted in the analyses.

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6.0 DESIGN AND CONSTRUCTION RECOMMENDATIONS

6.1 SITE DEMOLITION

Demolition, removal and/or relocation of existing asphalt pavement, underground utilities, light poles, etc. within the footprint of the proposed water supply tank will be critical to the successful installation of deep foundations and long-term performance of the new structure. It is important that both the existing at-grade and below-ground structures are removed/relocated and the associated debris is hauled to an appropriate landfill, properly recycled or stockpiled in an approved area of the site. CEC recommends that existing below-ground utilities and/or structures be completely removed and/or relocated from within the water supply tank footprint, including a minimum 10 feet wide buffer from the outside edge of the proposed ring foundation.

Construction debris generated from demolition is not considered suitable for use in on-site fills, unless the deleterious materials can be sorted and broken down sufficiently to meet the requirements of engineered fill (refer to Section 6.4) and approved by the owner and Geotechnical

Engineer.

CEC recommends that a designated representative of the Geotechnical Engineer be retained to observe and document the demolition activities. The geotechnical representative can verify that the intent of the demolition recommendations contained herein are being implemented, as well as identify and act upon unknown or unforeseen underground structures/utilities that are uncovered during the demolition.

6.2 TEMPORARY EXCAVATIONS

CEC recommends that all temporary excavations (utility trenches or foundation) comply with the most recent Occupational Safety and Health Administration (OSHA) Excavating and Trenching

Standard, Title 29 of the Code of Federal Regulation (CFR) Part 1926, Subpart P. This document was issued to better provide for the safety of workers entering trenches or excavations. This federal regulation mandates that excavations, whether they be utility trenches, excavations to made to

-18- CEC Project 163-428 remove existing structures or foundation excavations, be constructed in accordance with the OSHA guidelines. It is CEC’s understanding that these regulations are being strictly enforced and if they are not closely followed, the owner and the contractor could be liable for substantial penalties. The analyses, discussions, conclusions, and recommendations throughout this report are not to be intended as pre-engineering compliance with excavation safety regulations.

The contractor is solely responsible for designing and constructing stable, temporary excavations and should shore, slope, or bench the sides of the excavations as required to maintain stability of both the excavation sides and bottom. The contractor's "competent person", as defined in 29 CFR

Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety regulations.

Based on the encountered subsurface conditions and proposed site grades, temporary excavations will expose existing fill overlying natural coarse grained soil (Type C Soils); therefore, CEC recommends that temporary excavation slopes (exceeding a depth of 3 feet) be laid back to at least

1.5H:1V or properly braced/shored.

6.3 STRUCTURE FOUNDATIONS

It is recommended that the foundations of the proposed water tank be supported on a deep foundation system consisting of ACIP piles. Based on our pile load analyses, we recommend that the allowable axial and uplift pile capacities and the corresponding required maximum pile tip elevations for different diameter piles supported in the outwash deposit be determined as listed in

Tables I and II.

TABLE NO. I: ACIP PILE AXIAL AND UPLIFT CAPACITIES

(MAXIMUM PILE TIP @ ELEVATION 644 FEET AMSL)

Allowable Axial Load

(tons)

Allowable Uplift Capacity

(tons)

Diameter of ACIP Pile

(inches)

75 35 12

90 40 14

108 50 16

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TABLE NO. II: ACIP PILE AXIAL AND UPLIFT CAPACITIES

(MAXIMUM PILE TIP @ ELEVATION 639 FEET AMSL)

Allowable Axial Load

(tons)

Allowable Uplift Capacity

(tons)

Diameter of ACIP Pile

(inches)

85 45 12

105 50 14

120 60 16

CEC recommends that the ACIP pile design and pile installation include the following criteria:

• It is recommended that the ACIP piles for this project be designed by a registered professional engineer and is familiar with ACIP pile design and construction. The ACIP pile designer should be provided with this report, as well as the foundation layout, loads and settlement criteria established by the Structural Engineer of Record (SEO) to use as the basis for ACIP pile design. Overall, the ACIP design should include maximum pile capacities, maximum settlement, construction details, specifications and quality control requirements necessary to meet the foundation support criteria for the structure, as established by the SEO. The specifications should require verification of the required tip elevation of the piles. CEC recommends that the ACIP pile design and specifications be reviewed by the Geotechnical Engineer and SEO.

• Pile reinforcement should be such that it will satisfy the requirements of the Section 1810 of the IBC 2012. Cages or bars inserted into the fluid grout column should have centering devices to assure that the steel is installed to within structural tolerances.

• The pile design length(s) and associated minimum required penetration depth into the ground or bearing stratum should be based on the axial (downward and uplift) imparted by the structure and should be determined based on the information provided in Table Nos. I and II above. The pile capacities presented on these tables are based on the soil conditions presented in Figure 5 attached to this report and the applicable IBC 2012 minimum FS.

The axial and uplift pile capacities shown in Table Nos. I and II are based on a FS of 2 and 3, respectively. We recommend that the pile design length(s) be extended if the maximum settlement criteria established by the SEO for the project is less than 0.5 inches. The extended length will require additional analysis by the Geotechnical Engineer.

• The ACIP pile design should include associated construction specification and installation procedures in accordance to the requirements of the above-referenced FHWA Manual and include, but not limited to: 1) material specifications regarding the type, mix design and strength of grout or concrete; 2) minimum grout or concrete pressures during auger withdrawal; 3) minimum and maximum auger advancement and withdraw rates;

4) minimum grout or concrete volumes; 5) minimum construction distance and/or time

-20- CEC Project 163-428 between adjacent piles; 6) required submittals and approvals; 7) contractor qualifications;

and, 8) quality control/assurance.

• We recommend that at least one pile load test be conducted to verify the selected pile capacity at the recommended maximum tip elevation. We recommend that the location of the proposed load test be selected by the Geotechnical Engineer. The test pile should be the same diameter and type as the intended production piles and should be installed using procedures, equipment and materials identical to those that will be used for production piles. It is recommended that the pile load test setup be designed by the Contractor and that the shop drawings for the test pile location, setup and testing criteria be reviewed by the Project Structural Engineer and the Geotechnical Engineer in advance of the performance of the test. We recommend that the pile load test be accomplished in accordance with ASTM D1143, the standard loading procedure. After the test has been performed in accordance Paragraph 5.1 of the ASTM procedure mentioned above, we recommend reloading the test pile in accordance with Paragraph 5.3, “Loading In Excess Of Standard Test Load” to failure or to the limit of the reaction frame, where the reaction frame has been designed to resist a load equal to at least 3.5 times the production pile design load capacity. The Pile Foundation Contractor should be made responsible for the complete setup and performance of the tests. We recommend that the Geotechnical Engineer be retained to witness the installation of the test pile and the reaction piles, to witness the load test and prepare recommendations for design loads and tip elevation based upon load settlement curves and the Structural Engineer’s allowable settlement criteria.

• It is recommended that the individual piles and groups be spaced at least two times the pile diameter, but not less than 3 feet, center to center. We recommend that no reduction of the individual axial or uplift pile capacity for performance in groups be made. We recommend;

however, that in case the spacing between the piles is less than three times the diameter of the piles, the individual axial or uplift pile capacity be reduced by multiplying the individual pile capacity by a reduction factor. The reduction factor should be determined by the Geotechnical Engineer.

• We recommend that passive pressures be considered against part of pile caps located more than 30 inches below the finish exterior grades within the proximity of the ring foundation when resisting the lateral loads on the piles and the pile groups. For the existing on-site soils, we recommend that the passive pressures be estimated on the basis of an ultimate uniform passive earth pressure of 1,500 pounds per square foot of contact area. In case the magnitudes of the lateral loads on the ring foundation supporting the proposed tank structure are such that they cannot be economically resisted against parts of the ring foundations and hence lateral load bearing capacities of the piles will have be incorporated into the design, we recommend that at least one lateral load pile load test be performed to twice the design lateral load capacity of the piles to verify the soil parameters to be used in the lateral load computations. Provided that the lateral load test pile does not experience structural failure, the same pile may then be used for the axial pile load test.

• We recommend that proposals for the installation of the ACIP piles only be accepted from pre-qualified Contractors. In this regard, the selected Contractor should have a minimum of 5 years of experience with ACIP installation in this type of application.

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• Auger refusal during pile installation is not anticipated; however, should auger refusal during the pile installation be encountered, that is defined by advancement of the auger at a rate less than 12 inches in 1 minutes of augering of a fully toothed auger under the dead weight of the auger and drill head, the SEO and the Geotechnical Engineer should be advised and a new pile or a pair of piles installed in accordance with the Engineer's directions.

• The piles should be installed with proper well-maintained equipment capable of drilling straight and plumb holes to the necessary depths, and then maintaining high grout pressure during uniform withdrawal of the auger to prevent "necking" of the grout column. The auger should be slowly rotated during withdrawal and grouting. The installation should be sequenced so that no pile is drilled less than 20 hours after grout is placed in the adjacent pile within 8 feet, center to center. We recommend that the pumped grout volumes be monitored using automated monitoring equipment.

• We recommend that the piles be installed using a bottom center discharge auger to reduce the possibility of grout contamination due to side scour. The specifications should include an item to this effect.

• We recommend that the production piles not be accepted if any of the following conditions occur:

The design pile reinforcement cannot be placed manually in the top of any pile following the completion of the grouting.

The trap door at the bottom discharge outlet fails to open completely, effectively creating a side discharge condition.

Loss of grout head occurs for any reason during pile installation.

There is more than a 20 minute delay during grouting of any individual pile.

There is a drop in grout level after completion of the pile which exceeds the average of the other pile installations by more than 2 feet.

There is a rise in the grout level of any amount.

Should any of these occur, it will be necessary to redrill and regrout the individual pile for the pile to be considered acceptable as a production pile. The redrilling and regrouting should be included in the cost of the original pile installation and should not be considered extra.

• CEC recommends ACIP piles have integrity testing performed as part of the quality control/assurance criteria. The ACIP design engineer should develop and approve the specific criteria regarding integrity testing for this project (i.e., type of testing, qualifications, frequency, data, reporting, acceptance, etc.). The integrity testing data should be reported to the ACIP pile designer, Geotechnical Engineer and SEO for review and approval.

• We recommend that the installation of the pile foundations be monitored by the Geotechnical Engineer or a representative thereof in order to confirm that the installation of the piles is consistent with the intent of the project specifications. The monitoring should include confirmation of pile lengths, grouting pressures, grout volume, rate of auger

-22- CEC Project 163-428 withdrawal, changes in levels of completed grout columns and installation of design reinforcement. The pumped grout volumes should be monitored. In addition, the Geotechnical Engineer or representative of the Geotechnical Engineer should perform the specified field and laboratory testing of the ACIP pile materials to confirm conformance with the specifications.

6.4 ENGINEERED FILL AND SUBGRADE PREPARATION

CEC recommends that excavations made to construct the ring foundation and/or the fill to be placed to support the slab-on-grade floor for the tank or new pavements, including utility trench backfill, be constructed as engineered fill. Further, CEC recommends that representative samples of the proposed fill materials (on-site and imported soil) be collected and tested to determine their laboratory compaction characteristics, plasticity, and natural moisture content prior to initiating the earthwork activities. These tests are needed to determine if the proposed fill material is acceptable for the planned use, to identify materials for specific areas of the site, and for quality control during compaction.

The following criteria are recommended for engineered fill material selection:

• Engineered fill materials should meet the following requirements: 1) maximum Liquid Limit of 50 percent; 2) maximum Plastic Limit of 25 percent; 3) minimum laboratory maximum dry density of 100 pounds per cubic feet (pcf) (ASTM D 698); 4) maximum particle size of 6 inches; and, 5) less than 3 percent by weight fibrous, organic matter;

• Highly plastic soils (Liquid Limit above 50 percent or Plastic Limit above 25 percent) should be placed at least 3 feet below pavement or floor slab finished grades (where possible); and,

• Any debris that may be encountered in the fill…