W912PL21R0003_Solicitation_Specifications_Vol4.pdf

RFP NO. W912PL21R0003

U.S. ARMY CORPS

OF ENGINEERS

LOS ANGELES DISTRICT

REQUEST FOR PROPOSALS

FY21 AIRCRAFT HANGAR

YUMA PROVING GROUND, AZ

Construction Solicitation and Specifications

Volume 4

FULL & OPEN COMPETITION

MARCH 2021

UNCLASSIFIED // FOR OFFICIAL USE ONLY (FOUO)

UNCLASSIFIED // FOR OFFICIAL USE ONLY (FOUO)

US Army Corps

Of Engineers

Louisville District

PN 86022 / P2# 469672

SOF Hangar

Yuma Proving Ground, AZ

Corrected Final Submission

September 2020

Solicitation Number: TBD

Contract# W912QR-17-D-0038

Specifications

Volume 4 of 4

Distribution Statement D Distribution authorized to the DoD and U.S.

DoD contractors only; 12 September 2018.

Other requests for this document shall be referred to Commander, US Army Yuma Proving Ground, ATTN: Directorate of Public Works Yuma, AZ 85365-9498

TABLE OF CONTENTS

PN 86022 / P2 469672

YUMA SOF HANGAR

YUMA PROVING GROUND, AZ

Volume 4 - Appendices

Geotechnical Report (For Reference Only)

PN 86022 / P2 469672

YUMA SOF HANGAR

YUMA PROVING GROUND, AZ

Geotechnical Report (For Reference Only)

REPORT COVER PAGE

Geotechnical Engineering Report

Yuma SOF Hangar

Yuma Proving Grounds

Yuma, Arizona

August 26, 2020

Terracon Project No. 65185133 Revision No. 2

Prepared for:

Barge Design Solutions, Inc.

Miamisburg, Ohio

Prepared by:

Terracon Consultants, Inc.

Tempe, Arizona

Terracon Consultants, Inc. 4685 S. Ash Avenue, Ste. H-4 Tempe, AZ 85282 P (480) 897 8200 F (480) 897 1133 terracon.com

REPORT COVER LETTER TO SIGN

August 26, 2020

Barge Design Solutions, Inc.

1370 Vanguard Boulevard

Miamisburg, Ohio 45342

Attn: Mr. Scott DeGaro, RA

P: (937) 428-5243

E: scott.degaro@bargedesign.com

Re: Geotechnical Engineering Report

Yuma SOF Hangar

Yuma Proving Grounds

Yuma, Arizona

Terracon Project No. 65185133 Revision No. 2

Dear Mr. DeGaro:

Terracon Consultants, Inc. (Terracon) has completed the Geotechnical Engineering services for the above referenced project. This study was performed in general accordance with Terracon

Proposal No. P65185133 dated May 25, 2018. This report presents the findings of the subsurface exploration and provides geotechnical engineering recommendations concerning earthwork and the design and construction of foundations, floor slabs and pavements for the proposed project.

We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report or if we may be of further service, please contact us.

Sincerely, Terracon Consultants, Inc.

Eddy F. Ramirez, P.E. Donald R. Clark, P.E.

Geotechnical Project Manager Sr. Consultant/Sr. Principal

8/26/2020

Yuma SOF Hangar ■ Yuma, Arizona

August 26, 2020 ■ Terracon Project No. 65185133 Revision No. 2

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REPORT TOPICS

Page No.

INTRODUCTION

PROJECT DESCRIPTION

SITE CONDITIONS

EXPLORATION AND TESTING PROCEDURES

GEOTECHNICAL CHARACTERIZATION

FROST CONSIDERATIONS

CORROSIVITY

SEISMIC CONSIDERATIONS

LIQUEFACTION

GEOTECHNICAL OVERVIEW

SHALLOW FOUNDATIONS

DEEP FOUNDATIONS

FLOOR SLABS

LATERAL EARTH PRESSURES

PAVEMENTS

EARTHWORK

GENERAL COMMENTS

FIGURES

Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section and clicking on the

GeoReport logo will bring you back to this page.

ATTACHMENTS

Exhibit No.

SITE LOCATION.......................................................................................................... A-1

EXPLORATION PLANS ......................................................................................... A-2 and A-3

EXPLORATION RESULTS

General Notes ............................................................................................................. A-4

Unified Soil Classification System ................................................................................ A-5

Boring Logs .................................................................................................. A-6 thru A-45

Atterberg Limits Results.................................................................................. B-1 thru B-3

Grain Size Distribution .................................................................................. B-4 thru B-14

Moisture-Density Relationship Results ....................................................... B-15 thru B-23

California Bearing Ratio (CBR) Results ...................................................... B-24 thru B-30

Consolidation Results ................................................................................................ B-31

Summary of Laboratory Results ................................................................. B-32 thru B-34

Field Soil Electrical Resistivity Test Data ..................................................................... C-1

Percolation Testing Results ........................................................................... D-1 thru D-4

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Table of Contents (Continued)

REMI SURVEY REPORT

Southwest Geophysics, LLC ReMi Survey Report dated December 17, 2018.

ENGINEERING ANALYSIS CALCULATIONS

Engineering Analysis Calculations ................................................................ E-1 thru E-20

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REPORT SUMMARY

Topic 1 Overview Statement

Project Description

We understand the project will include construction of an approximate 46,653 square-foot single-story, high bay hangar building. Other improvements to the site will include canopies and new paved parking and drives for automobile traffic, and new paved aircraft taxiways and aprons for aircraft traffic. The project will also include underground corrugated metal pipes (CMP) for storm-water detention and/or retention basins.

Geotechnical Characterization

The subsurface soils encountered at the surface to a depth of about 4 to 10 feet consist of loose to medium dense silty sand with variable amounts of gravel and poorly graded sand with variable amounts of silt and gravel, and underlying by medium dense to very dense silty sand with variable amounts of gravel, poorly graded sand with variable amounts of silt and gravel, and hard clay with variable amounts of silt, sand, and gravel extending to the maximum depth of exploration of

76½ feet.

Asphalt and/or aggregate base course (ABC) were encountered in Boring No. B-10, and B-18. One foot of fill material was encountered at the surface in Boring No. B-1.

Groundwater was not encountered in the borings to the maximum depth of exploration of 76 ½ feet below existing site grade.

Shallow Foundations

Shallow foundations can be utilized for the support of the proposed hangar building.

■ Footing proportioning analyses have been completed for the design of spread footings for the range of anticipated column and wall loads as shown on the Allowable Footing Load Graphs in the Figures section of this report.

■ The analyses are for footings bearing at a minimum depth of 2 feet below finished grade.

■ Shallow foundations should be supported on engineered fill as outlined in the Earthwork section of the report.

■ Expected settlements: 1 inch or less total, ¾ inch or less differential

■ As an alternative to shallow foundations supported on engineered fill, the proposed hangar building may be supported by shallow spread footings bearing on existing soils improved by Rammed Aggregate Pier (RAP) elements, or a similar and equivalent type of ground improvement system.

Additional collaboration between the structural engineer and the RAP specialty contractor should be conducted if this alternative is considered for the project.

Shallow foundations can be utilized for the proposed lightly loaded canopies.

■ Maximum allowable bearing pressure = 1,500 psf with a minimum 18-inch embedment depth.

■ Expected settlements: 1 inch or less total, ¾ inch or less differential

■ Shallow foundations for the proposed lightly loaded canopies can be supported on undisturbed native soils.

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Topic 1 Overview Statement

Deep Foundations

As an alternate foundation system, deep foundations can be considered for the support of the proposed hangar building. Drilled shaft allowable load-capacity curves and design parameters for drilled shaft foundations are provided in the Deep

Foundations section of this report. In order to reduce differential settlements, foundations for the project should consist solely of either shallow spread footings or deep foundations. If the project includes both shallow spread footings and deep foundations, differential settlements between these structural elements should be further evaluated and considered in the design and construction of the project.

Earthwork

■ In shallow foundation areas for the proposed hangar building, remove and recompact the existing soils to a minimum depth of 3 feet below the footing bottom or 5 feet below existing site grades, whichever depth is greater. Removal should extend a minimum of 5 feet laterally beyond the edges of footings. If shallow foundations are supported on existing soils improved by Rammed Aggregate Pier elements, removal and recompaction of the existing soils is not required.

■ Shallow foundations bearing entirely upon undisturbed native soils are recommended for support of lightly loaded canopies. If unsuitable bearing soils or fill materials are encountered at the base of the planned foundation excavations, the excavations should be extended deeper to suitable native soils, and the footings could bear directly on these soils at the lower level. Alternatively, the deepened excavations could be backfilled to planned foundation bearing depth with engineered fill or with lean concrete placed in the excavations.

■ Subgrade soils beneath interior and exterior floor slabs and pavements should be scarified, moisture conditioned and compacted to a minimum depth of 10 inches.

Below-Grade Structures

No basements are planned.

Pavements

Recommended minimum pavement sections of on-site drives and parking areas for the project, based on three levels of anticipated traffic loading, and with subgrade preparation as noted in Earthwork are as follows:

Asphalt:

■ 3.0” AC over 4” ABC in Light Duty Areas

■ 3.0” AC over 6” ABC in Medium Duty Areas

■ 4.0” AC over 6” ABC in Heavy Duty Areas

Concrete:

■ 5.0” PCC over 4” ABC in Light Duty Areas

■ 6.0” PCC over 4” ABC in Medium Duty and Trash Enclosure Areas

■ 7.0” PCC over 4” ABC in Heavy Duty Areas

Our scope of work for design of the planned aircraft taxiways and aprons pavement structure was limited to providing California Bearing Ratio (CBR) from laboratory test data) and modulus of subgrade reaction (ks, from published correlations) values.

Pavement structure/section design for the planned airfield pavements will be performed by others.

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Topic 1 Overview Statement

General Comments

This section contains important information about the limitations of this geotechnical engineering report.

1. If the reader is reviewing this report as a pdf, the topics above can be used to access the appropriate section of the report by simply clicking on the topic itself.

2. This summary is for convenience only. It should be used in conjunction with the entire report for design purposes.

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INTRODUC TION

Geotechnical Engineering Report

Yuma SOF Hangar

Yuma Proving Grounds

Yuma, Arizona Terracon Project No. 65185133 Revision No. 2

August 26, 2020

INTRODUCTION

This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed Yuma SOF Hangar to be located at the Yuma Proving

Grounds in Yuma, Arizona. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

■ Subsurface soil conditions ■ Foundation design and construction

■ Groundwater conditions ■ Floor slab design and construction

■ Site preparation and earthwork ■ Seismic site classification per IBC

■ Lateral earth pressures

■ Excavation considerations

■ Pavement design and construction

■ Pavement subgrade data for aircraft areas

Our geotechnical engineering scope of work for this project included the following:

■ Forty (40) test borings were drilled to approximate depths ranging from 10½ to 76½ feet in the proposed hangar building, pavement, and stormwater retention areas;

■ Two (2) field soil electrical resistivity tests;

■ One refraction microtremor (ReMi) survey in the proposed hangar building area;

■ Percolation testing at four (4) locations in the proposed underground corrugated metal pipes (CMP) and/or retention basin areas;

■ Laboratory testing of soil samples;

■ Geotechnical engineering analyses; and,

■ Preparation of this report

The map showing the site location is attached as Site Location (Exhibit A-1). Boring locations are shown on the attached Exploration Plan (Exhibits A-2 and A-3). A log of each boring is included in the Exploration Results section of this report (Exhibits A-6 thru A-45). The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included on the boring logs and the Exploration Results section of this report (Exhibits B-1 thru B-34). The field soil electrical resistivity test data is included in the Exploration Results (Exhibit

C-1). The percolation test results are presented in the Exploration Results section (Exhibits D-1 through D-4). The results of the ReMi survey is provided in the Southwest Geophyics, LLC report presented in the ReMi Survey Report section of this report. The engineering calculations completed to support the geotechnical engineering recommendations concerning earthwork and

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PROJECT DESCRIPTION

Item Description

Project Description

We understand the project will include construction of an approximate 46,653 square-foot single-story, high bay hangar building. Other improvements to the site include canopies and new paved parking and drives for automobile traffic and new paved aircraft taxiways and aprons for aircraft traffic. The project will also include underground corrugated metal pipes (CMP) for storm-water retention and/or retention basins constructed as part of the project.

Our scope of work for design of the planned aircraft taxiways and aprons pavement structure is limited to providing California Bearing Ratio (CBR) laboratory test data and modulus of subgrade reaction (ks, from published correlations) values. Pavement structure/section design for the planned airfield pavements will be performed by others.

Proposed

Construction

We anticipate the proposed hangar building will consist of a steel-frame superstructure supported on either shallow spread footings or a deep foundation system. We anticipate that the floor of the proposed hangar building will be a concrete slab-on-grade or concrete pavement.

Maximum Loads

(provided)

■ Columns: 650 kips maximum

■ Walls: 4 to 6 kips per linear foot maximum

■ Slabs: 150 pounds per square foot maximum

Grading Minor cuts and fills on the order of up to two feet are anticipated for the site.

Below Grade

Structures None are planned.

Retaining Walls None are planned.

Pavements

On-site drives and parking area pavements for automobile and truck traffic are anticipated to consist of asphalt concrete and portland cement concrete.

Traffic information for the planned development was not provided; therefore, we have assumed the following traffic information and anticipated design equivalent single axle loads (ESALs) for the on-site pavements:

■ Automobile Drives and Parking Areas: 7,000 ESALs

■ Main Drives and Light Truck Drive Areas: 27,000 ESALs

■ Heavy Truck Traffic Drive Areas: 110,000 ESALs

The pavement design period is 20 years

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Item Description

Storm-water

Retention Basins

We understand the proposed project may include underground corrugated metal pipes (CMP) for storm-water detention. The storm-water retention

CMPs are planned to be constructed beneath paved areas.

Storm-water retention basins are also planned to be constructed as part of the proposed project. The depth of the bottom of the retention basins will be approximately 3 to 5 feet below grade.

SITE CONDITIONS

Item Description

Parcel Information The project is located at the Yuma Proving Grounds in Yuma, Arizona. See

Site Location (Exhibit A-1) for additional site location information.

Existing

Improvements

The project site is located inside the existing Laguna Army Airfield with several buildings, hangars, and ancillary structures with paved parking, drives, taxiways, and aprons.

Surrounding

Improvements

North: Native Desert.

South: Hangar buildings and paved aprons and taxiways.

East: Paved aprons and taxiway.

West: Military base structures and paved drives and parking.

Current Ground Cover Light growth of vegetation, asphalt materials on the southeast of the site, and concrete pavement panels along the east and north ends of the site.

Existing Topography Relatively flat.

EXPLORATION AND TESTING PROCEDURES

Field Exploration

A total of 40 borings were drilled at the project site on December 4 through 11, 2018. The approximate boring locations are shown on the Exploration Plan (Exhibits A-2 and A-3) and are summarized in the following table:

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Number of Borings Boring Nos.

Boring Depth

(feet) Planned Location

10 B-36 thru B-45 35 to 76½ Proposed Hangar Building

4 B-18 thru B-21 10½ to 11½ Proposed UFD Pavement Areas

7 B-1 thru B-7 10½ to 15½ Proposed Hangar Access Apron

6 B-8 thru B-13 11½ to 15½ Proposed Aircraft Loading Apron

4 B-14 thru B-17 10½ to 15½ Proposed Taxiway Foxtrot

5 B-22 thru B-26 10½ to 15½ Proposed Taxiway Alpha Extension

4 P-1 thru P-4 20½ to 21½ Proposed Retention Areas

Boring Layout and Elevations: Barge Design Solutions, Inc. personnel provided the boring layout. Coordinates for each boring were obtained with a handheld GPS unit (estimated horizontal accuracy of about ±10 feet). If elevations and a more precise boring layout is desired, we recommend the borings be surveyed.

Subsurface Exploration Procedures: The borings were advanced with a truck-mounted CME-

75 drill rig utilizing 8-inch outside diameter hollow-stem augers. At selected intervals, samples of the subsurface materials were taken at each boring location by driving split-spoon (SPT) or ring-lined barrel samplers in general accordance with ASTM Standards. In the split-barrel sampling procedure, a standard 2-inch outer diameter split-barrel sampling spoon is driven into the ground by a 140-pound automatic hammer falling a distance of 30 inches. The number of blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration is recorded as the

Standard Penetration Test (SPT) resistance value. The SPT resistance values, also referred to as

N-values, are indicated on the boring logs at the test depths. A 3-inch O.D. split-barrel sampling spoon with 2.5-inch I.D. ring lined sampler was used for sampling in the upper ten feet in the soil borings. Ring-lined, split-barrel sampling procedures are similar to standard split spoon sampling procedure; however, blow counts are typically recorded for 6-inch intervals for a total of 12 inches of penetration. Bulk samples of subsurface materials were obtained from all the borings.

Groundwater was not observed in any of the borings during the field exploration. For safety purposes, all borings were backfilled with auger cuttings after their completion.

Our exploration team prepared field boring logs as part of the drilling operations. The sampling depths, penetration distances, and other sampling information were recorded on the field boring logs. These field logs included visual classifications of the materials encountered during drilling and our interpretation of the subsurface conditions between samples. The samples were placed in appropriate containers and taken to our soil laboratory for testing and classification by a geotechnical engineer. Final boring logs were prepared from the field logs. The final boring logs represent the geotechnical engineer's interpretation of the field logs and include modifications based on observations and tests of the samples in our laboratory.

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Field Soil Electric Resistivity Testing

Two (2) field measurements of soil resistivity tests were performed on December 17, 2018. The approximate soil resistivity test locations are shown on the attached Exploration Plan (Exhibit A-

2). Field measurements of soil resistivity were performed in general accordance with ASTM Test

Method G 57, and IEEE Standard 81, using the Wenner Four-Electrode Method. The soil resistivity measurements were performed using a MiniSting, Memory Earth Resistivity and IP

Meter, manufactured by Advanced Geosciences, Inc. The Wenner arrangement (equal electrode spacing) was used with the “a” spacings of 2½, 5, 10, 20, 30, 40, and 50 feet. The “a” spacing is generally considered to be the depth of influence of the test. Results of the soil resistivity measurements are presented in tabular and graphical format in the attached Exploration Results section of this report (Exhibit C-1).

Laboratory Testing

Samples retrieved during the field exploration were taken to the laboratory for further observation by the project geotechnical engineer and were classified in accordance with the Unified Soil

Classification System (USCS) described in Exhibit A-5. At that time, the field descriptions were confirmed or modified as necessary and an applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials.

General laboratory tests were conducted on selected soil samples and the test results are presented in the Exploration Results (Exhibits B-1 through B-34) section of this report. These results were used for the geotechnical engineering analyses, and the development of foundation recommendations. Laboratory tests were performed in general accordance with the applicable

ASTM, local or other accepted standards, and included the following:

■ ASTM D2216 Standard Test Methods for Laboratory Determination of Water (Moisture)

Content of Soil by Mass

■ ASTM D4318 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils

■ ASTM D422 Standard Test Method for Particle-Size Analysis of Soils

■ ASTM D2435/D2435M Standard Test Methods for One-Dimensional Consolidation

Properties of Soils Using Incremental Loading

■ ASTM D-7263 Standard Methods for Dry Unit Weight of Soil

■ ASTM D1557 Standard Test Methods for Laboratory Compaction Characteristics of Soil

Using Modified Effort (56,400 ft-lbf/ft3 (2,700 kN-m/m3))

■ ASTM D1883 Standard Test Method for California Bearing Ratio (CBR) of Laboratory-

Compacted Soils

■ ASTM D516 Standard Test Method for Sulfate Ion in Water

■ ASTM G187 Standard Test Method for Measurement of Soil Resistivity Using the Two-

Electrode Soil Box Method

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■ ASTM D4972 Standard Test Method for pH of Soils

■ ASTM D512 Standard Test Methods for Chloride Ion in Water

GEOTECHNICAL CHARACTERIZATION

Geology

The project area is located in the Basin and Range physiographic province (1Cooley, 1967) of the

North American Cordillera (2Stern, et al, 1979) of the southwestern United States. The southern portion of the Basin and Range province is situated along the southwestern flank of the Colorado

Plateau and is bounded by the Sierra Nevada Mountains to the west. Formed during middle and late Tertiary time (100 to 15 million years ago), the Basin and Range province is dominated by fault-controlled topography. These mountain ranges and valleys have evolved from generally complex movements and associated erosional and depositional processes.

Surficial geologic conditions mapped at the site (3Richard, et al, 2000) consist of Quaternary

Surficial deposits, undivided. This unit consists of unconsolidated to strongly consolidated alluvial and eolian deposits. This unit includes: coarse, poorly sorted alluvial fan and terrace deposits on middle and upper piedmonts and along large drainages; sand, silt and clay on alluvial plains and playas; and wind-blown sand deposits.

Subsurface Profile

Specific conditions encountered at each boring location are indicated on the individual boring logs presented in the attached Exploration Results (Exhibits A-5 thru A-45). Stratification boundaries on the boring logs represent the approximate location of changes in soil types; in-situ, the transition between materials may be gradual. Based on conditions encountered in the borings, subsurface conditions on the project site can be generalized as follows:

1 Cooley, M.E., 1967, Arizona Highway Geologic Map, Arizona Geological Society.

2 Stern, C.W., et al, 1979, Geological Evolution of North America, John Wiley & Sons, Santa Barbara, California.

3 Richard, S. M., Reynolds, S.J., Spencer, J. E., and Pearthree, P. A., 2000, Geologic Map of Arizona: Arizona Geological Survey

Map 35, 1 sheet, scale 1:1,000,000.

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Description

Approximate

Depth to Bottom of

Stratum (feet)

Material Description Relative Density /

Consistency

Surface 1 0.5

3 inches of Asphalt over

4.5 inches of ABC

Stratum 1 2 4 to 10

Silty Sand with variable amounts of gravel, Poorly Graded Sand with variable amounts of silt and gravel

Loose to Medium

Dense

Stratum 2 39 to 41

Silty Sand with variable amounts of gravel, Poorly Graded Sand with variable amounts of silt and gravel, Sandy Lean

Clay, Lean Clay with sand

Medium Dense to Very

Dense / Hard

Stratum 3 65 to 70

Silty Sand with variable amounts of sand, Poorly Graded Sand with variable amounts of sand, Medium Dense to

Very Dense

Stratum 4 76½ (maximum depth explored)

Sandy Lean Clay, Silty Clay with variable amounts of sand and gravel Hard

1.

Asphalt and/or aggregate base course (ABC) was encountered in Boring No. B-10 and B-18.

2.

Twelve (12) inches of fill material was encountered at the surface in Boring No. B-1.

Laboratory tests were conducted on selected soil samples and the test results are presented in the attached Exploration Results (Exhibits B-1 thru B-34). Test results indicate the near surface sand soils exhibit non-plastic characteristics.

When water was added to samples of laboratory compacted sand soils obtained from the proposed project site, the compacted soils exhibited low expansive potential when subjected to light loading conditions such as those imposed by lightly loaded interior floor slabs.

In response to wetting of a relatively undisturbed sample while supporting typical foundation loads, the near surface and near surface soils exhibited variable low hydro-compaction (collapse) potential at in-situ moisture content and density. These same soils show low compression under typical foundation pressures.

Groundwater Conditions

Groundwater was not observed in any of the test borings at the time of our field exploration, nor when checked upon completion of drilling. These observations represent groundwater conditions at the time of the field exploration and may not be indicative of other times, or at other locations.

Groundwater conditions can change with varying seasonal and weather conditions, and other factors.

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Based on information obtained from the Arizona Department of Water Resources – Groundwater

Data website (https://gisweb.azwater.gov/waterresourcedata/GWSI.aspx), the depth to regional groundwater was measured to be approximately 199 feet below the ground surface at an Arizona

Department of Water Resources (ADWR) monitored well site (Local I.D.: C-06-21 34DBA) located approximately 1,600 feet south of the site.

Percolation Test Results

Percolation testing was conducted at the location of the planned on-site stormwater retention corrugated steel pipes (CMP) and basin areas and the results are summarized as follows:

Percolation Test Results

Test Hole Depth

(feet) Soil Classification

Infiltration Rate

(minutes/inch)

P-1 4 Silty Sand 3.2

P-2 4 Poorly Graded Sand with Silt 9.8

P-3 4 Silty Sand 4.0

P-4 4 Poorly Graded Sand 8.9

It should be noted that siltation and vegetation growth along with other factors may affect the infiltration rates of the on-site retention basin areas. The percolation rate presented in this report is an unfactored field measurement, and a de-rating factor should be applied to the percolation rate during the design of the proposed storm-water retention basin (performed by others).

We recommend that excavations for retention basins be excavated with light weight equipment to help reduce compaction of the basin bottom surface which will ultimately be used for infiltration of storm water. Once constructed, no traffic should be allowed to travel across the basin bottom.

It should be noted that compaction of the basin bottom will result in reduced percolation rate. If compaction of the basin bottom does occur, the exposed surface should be scarified to a minimum depth of 8 inches and left uncompacted.

FROST CONSIDERATIONS

Based on data obtained from the National Resources Conservation Service (NRCS) reported frost depth at the project site is approximately 0 to 2 inches.

https://gisweb.azwater.gov/waterresourcedata/GWSI.aspx

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CORROSIVITY

The following table lists the results of laboratory soluble sulfate, soluble chloride, electrical resistivity, and pH testing. The values may be used to estimate potential corrosive characteristics of the on-site soils with respect to contact with the various underground materials which will be used for project construction.

Corrosivity Test Results Summary

Location

Sample

Depth

(feet)

Soil Description pH

Electrical

Resistivity

(Ω-cm)

Soluble

Sulfate

Content

(ppm)

Soluble

Chloride

Content

(ppm)

B-9 0 – 5 Silty Sand 9.0 6,801 10 15

B-12 0 – 5 Silty Sand 8.8 4,060 38 37

B-15 0 – 5 Silty Sand 8.6 3,231 10 47

B-22 0 – 5 Silty Sand 8.1 409 405 838

B-26 0 – 5 Well Graded Sand with Silt

8.2 326 538 519

B-37 0 – 5 Silty Sand 8.3 674 303 196

B-38 0 – 5 Poorly Graded Sand with Silt

8.2 489 466 190

B-41 0 – 5 Silty Sand 8.2 809 62 180

B-43 0 – 5 Silty Sand 8.4 1,191 241 80

B-44 0 – 5 Silty Sand 8.6 3,836 4 36

P-1 5 – 10 Poorly Graded Sand with Silt

9.6 11,910 7 22

P-2 5 – 10 Poorly Graded Sand with Silt

8.9 6,769 4 34

P-3 5 – 10 Poorly Graded Sand 8.3 699 144 225

P-4 5 – 10 Poorly Graded Sand 8.3 904 331 350

Results of soluble sulfate testing indicate that samples of the on-site soils tested classify as S0 according to Table 19.3.1.1 of Section 318 of the American Concrete Institute (ACI) Building Code

Requirements for Structural Concrete. Concrete should be designed in accordance with the provisions of the ACI Building Code Requirements for Structural Concrete, Section 318, Chapter

19.

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These values should be used to help determine potential corrosive characteristics of the on-site soils with respect to contact with the various underground materials which will be used for project construction. Refer to Summary of Laboratory Results contained in Exploration Results

(Exhibits B-32 thru B-34) for the complete results of the corrosivity testing performed on the site soils in conjunction with this geotechnical exploration. The corrosion information presented is specific to the samples tested. If the actual soils that will be in contact with the structures at the site are different than those tested, then additional corrosion testing should be performed.

Terracon is not a corrosion engineer, and our scope of work was limited to performing corrosion laboratory tests on selected samples, presenting these results, and providing a brief comparison of the results to selected criteria. A qualified corrosion engineer should be consulted if corrosion of underground utilities and structures is a concern.

SEISMIC CONSIDERATIONS

The seismic design requirements for buildings and other structures are based on Seismic Design

Category. Site Classification is required to determine the Seismic Design Category for a structure.

The Site Classification is based on the upper 100 feet of the site profile defined by a weighted average value of either shear wave velocity, standard penetration resistance, or undrained shear strength in accordance with Section 20.4 of ASCE 7 and the International Building Code (IBC).

Southwest Geophysics LLC performed one refraction microtremor (ReMi) survey in the proposed hangar building area. Based on their analysis of the collected data from the ReMi survey, the average characteristic site shear-wave velocity down to a depth of approximately 100 feet is 1,250 feet per second. Based on that result the Seismic Site Classification is “C”. The geophysical evaluation report from Southwest Geophysics LLC is attached in the ReMi Survey Report section of this report.

Faulting and Estimated Ground Motion

The subject site is located in Southwest Arizona, which is a seismically active area. The type and magnitude of seismic hazards affecting the site are dependent on the distance to causative faults, the intensity, and the magnitude of the seismic event. The following table indicates the distance of the fault zones and the associated maximum credible earthquake that can be produced by nearby seismic events, as calculated using the USGS Unified Hazard Tool interactive deaggregations.

Characteristics and Estimated Earthquakes for Regional Faults

Fault Name Approximate Distance to

Site (kilometers)

Maximum Credible Earthquake

(MCE) Magnitude

Cerro Prieto 93.44 6.98

Algodones 50 29.61 6.70

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LIQUEFACTION

Liquefaction occurs when dynamic loading of a saturated sand or silt causes pore-water pressures to increase to levels where grain-to-grain contact is lost and the material temporarily behaves as a viscous fluid. Liquefaction can cause settlement of the ground surface, settlement and tilting of structures, flotation of buoyant buried structures and fissuring of the ground surface.

A common manifestation of liquefaction is the formation of sand boils -–short-lived fountains of soil and water that emerge from fissures or vents and leave freshly deposited conical mounds of sand or silt on the ground surface.

Based on the depth to groundwater and the subsurface soil conditions at the project site, liquefaction potential is considered to be relatively low.

GEOTECHNICAL OVERVIEW

Based on the information obtained from our subsurface exploration, the following geotechnical engineering considerations were identified:

n The on-site near surface soils generally consist of silty sand with variable amounts of gravel and poorly graded sand with variable amounts of silt and gravel soils. Field penetration test results indicate that the relative density of the near surface sand soils is generally loose to medium dense.

n Based on the field exploration, relatively loose soils are expected at shallow foundations depths. Based on the maximum loads for the proposed hangar building, we recommend shallow foundations system for the proposed hangar building be supported on engineered fill as outlined in the Earthwork section of this report. Shallow foundations for the lightly loaded proposed canopies, maximum loads on the order of 5 kips or less, can be supported on undisturbed native soils.

n As an alternative to shallow foundations supported on engineered fill, the proposed hangar building may be supported by shallow spread footings bearing on existing soils improved by

Rammed Aggregate Pier (RAP) elements, or a similar and equivalent type of ground improvement system. Additional collaboration between the structural engineer and the RAP contractor should be conducted if this alternative is considered for the project.

n As an alternative to shallow foundations, the proposed hangar building can be supported on drilled shaft foundations. Recommendations for drilled shaft foundations are provided in the

Deep Foundations section of this report.

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Responsive ■ Resourceful ■ Reliable 12 n Laboratory test results indicate the near surface soils exhibited non-plastic characteristics and low expansive potential when compacted. We recommend the upper 10 inches of finished subgrade soils beneath the interior floor slab and aggregate subbase be scarified, moisture conditioned as required, and compacted as outlined in the Earthwork section of this report.

n Asphalt concrete and rigid pavement systems are considered suitable for this site. The

Pavements section addresses the design of the pavement systems for automobile and truck traffic areas of the project. The design of airfield pavements will be conducted by others..

n The on-site soils are considered suitable for use as engineered fill in all construction areas of the project site.

n Based on the geophysics evaluation performed by Southwest Geophysics LLC, the site is classified as Site Class C in accordance with Chapter 20 of ASCE 7 as required by the 2012

International Building Code.

Geotechnical engineering recommendations for foundation systems and other earth connected phases of the project are outlined below. The recommendations contained in this report are based upon the results of field and laboratory testing (attached in Exploration Results), engineering analyses (attached in Engineering Analysis Calculations), and our current understanding of the proposed project.

The General Comments section provides an understanding of the report limitations.

SHALLOW FOUNDATIONS

If the site has been prepared in accordance with the requirements noted in Earthwork, the following design parameters are applicable for shallow foundations.

Shallow Spread Foundations Supported by Engineered Fill for Hanger Building

The proposed hanger building can be supported by shallow spread footings bearing on engineered fill. Design recommendations for foundations for these structures and related structural elements are presented as follows.

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Design Item Description/Recommendations

Maximum Net Allowable

Bearing Pressure 1,2 See Allowable Footing Load Graphs in the Figures section of this report.

Minimum Embedment Depth

Below finished grade 3 2 feet

Bearing Material Compacted engineered fill placed within the geometric configurations and depths below footings as outlined in

Earthwork section of this report.

Minimum footing dimensions

Isolated Column Footings: 24 inches

Continuous Wall Footings: 18 inches

Estimated total settlement 2 1 inch or less

Estimated differential settlement 2 ¾ of the total settlement

1.

The maximum net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation. The allowable bearing pressure may be increased by one-third when considering the alternative load combinations of Section 1605.3.2 of the 2012 International Building Code, however, it should not be increased when loads are determined by the basic allowable stress design load combinations of Section 1605.3.1.

2.

Values provided are for maximum loads noted in Project Description.

3.

Finished grade is defined as the lowest adjacent grade within 5 feet of the foundation for perimeter (or exterior) footings and finished floor level for interior footings.

For the range of anticipated structural loading conditions for the proposed hanger building, design of spread-footing foundations will likely be controlled by a combination of limiting bearing capacity and settlement. Footing proportioning analyses was completed for the design of spread footings for the range of column and wall loads as shown on the Allowable Footing Load Graphs in the

Figures section of this report. The analyses are for footings bearing at a minimum depth of 2 feet below finished grade. Total settlement of footings selected in accordance with the criteria outlined on the Allowable Footing Load Graphs is estimated to be 1 inch or less; differential settlement between adjacent footings is estimated to be ¾-inch or less.

Footings, foundations, and walls should be reinforced as necessary to reduce the potential for distress caused by differential foundation movement. The use of joints at openings or other discontinuities in walls is recommended.

Foundation excavations should be observed by the geotechnical engineer. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required.

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Shallow Spread Foundations Recommendations – Canopies

We understand canopies are planned for the proposed project. We understand these canopies structures will have relatively light column loads (on the order of 5 kips or less). The small single-story carport structures can be supported by shallow spread footing foundations bearing on undisturbed native soils. Design recommendations for foundations for these lightly loaded canopy structures are presented as follows.

Design Item Description/Recommendations

Maximum Net Allowable

Bearing Pressure 1,2 1,500 psf

Minimum Embedment Depth

Below finished grade 3 18 inches

Bearing Material Undisturbed native soils

Minimum footing dimensions Isolated Column Footings: 24 inches

Estimated total settlement 2 1 inch or less

Estimated differential settlement 2 ¾ of the total settlement

1.

The maximum net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation. The allowable bearing pressure may be increased by one-third when considering the alternative load combinations of Section 1605.3.2 of the 2012 International Building Code, however, it should not be increased when loads are determined by the basic allowable stress design load combinations of Section 1605.3.1.

2.

Values provided are for maximum loads on the order of 5 kips or less.

3.

Finished grade is defined as the lowest adjacent grade within 5 feet of the foundation for perimeter (or exterior) footings and finished floor level for interior footings.

Foundations should be reinforced as necessary to reduce the potential for distress caused by differential foundation movement. The use of joints at openings or other discontinuities in walls is recommended.

Foundation excavations should be observed by the geotechnical engineer. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required.

Spread Footing Foundations Supported by Rammed Aggregate Piers

A Rammed Aggregate Pier system may be considered as a means of ground improvement to support shallow foundations for the proposed hangar building as opposed to the use of

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Rammed Aggregate Pier (RAP) systems will improve the existing subgrade below the bottom of foundations at this site to allow for shallow foundation support of the structural loads. Piers with diameters ranging from 18 to 36 inches are constructed by advancing a drill or mandrel to design depths (for this project would extend from the bottom of the footing elevation to depths ranging from 10 to 20 feet), then building a bottom bulb of clean, open-graded stone. The pier is built on top of the bottom bulb, using graded aggregate (12 to 24 inches compacted thickness). The result of construction is a reinforced zone of soils directly under footings, which allows for the construction of shallow spread footings sized for relatively high bearing pressures without the need to remove existing soils and then construct an engineered fill section.

Rammed Aggregate Pier systems should be designed and constructed by a specialty geotechnical contractor. The specialty geotechnical contractor should provide detailed design calculations sealed by a professional engineer licensed in the State of Arizona and reviewed by

Terracon. The design calculations should demonstrate that the RAP foundation support system can control total and differential settlements in accordance with the project design requirements.

Additional collaboration between the structural engineer and the RAP contractor should be conducted for the project.

Footings Subject to Uplift Loads

Reinforced concrete dead-man foundations, cast-in excavations against undisturbed subsoils are recommended for resistance to uplift. Footing or dead-man foundations may be designed using the cone method. The equation for determining the ultimate uplift capacity as a function of footing or dead-man foundation dimension, foundation depth, and soil weight is presented below:

Tu = 0.63g x D2 x (B + L) + W

Where: Tu = Ultimate uplift capacity (lbs) g = Unit weight of soil (lbs/ft3)*

D = Depth to base of footing/dead-man foundation below final grade (ft)

B = Width of footing/dead-man foundation (ft)

L = Length of footing/dead-man foundation (ft)

W = Weight of footing/dead-man + weight of soil directly over the top of the footing/block (lbs)

*A unit weight (g) of 110 pcf is recommended for soil (either undisturbed or compacted backfill) at this site.

The design uplift resistance should be calculated by dividing the ultimate resistance obtained from the equation above by an appropriate factor of safety. A factor of safety of at least 2 is recommended for live uplift loads in the analysis.

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Foundation Construction Considerations

As noted in Earthwork section of this report, the footing excavations should be evaluated under the direction of the Geotechnical Engineer. The base of all foundation excavations should be free of water and loose soil, prior to placing concrete. Concrete should be placed soon after excavating to reduce bearing soil disturbance. Care should be taken to prevent wetting or drying of the bearing materials during construction. Extremely wet, loose or disturbed material in the bottom of the footing excavations should be removed before foundation concrete is placed. Should the soils at bearing level become excessively disturbed or saturated, the affected soil should be removed prior to placing concrete.

DEEP FOUNDATIONS

Drilled Shaft Design Parameters

As an alternative foundation to shallow spread footings, drilled shaft foundations may be considered for support of the proposed hangar. Drilled shaft foundations should have a minimum diameter of 3 feet. All drilled shaft foundations should have a minimum embedment depth of 18 feet or 4B (where B is the shaft diameter), whichever is greater.

The recommended allowable axial capacities of straight sided drilled shaft foundations for the proposed hangar building are presented in the Figures section of this report. The allowable capacities are based on utilizing both side friction and end bearing components of resistance.

Post-construction settlements of drilled shafts designed and constructed as described in this report are estimated to be less than 1 inch. Differential settlement between different size shafts are estimated to be ¾ of total settlement.

All shafts should be reinforced full-depth for the applied axial, lateral and uplift stresses imposed.

Drilled shaft should have a minimum (center-to-center) spacing of 6 diameters. Closer spacing may require a reduction in axial load capacity. Axial capacity reduction can be determined by comparing the allowable axial capacity determined from the sum of individual piles in a group versus the capacity calculated using the perimeter and base of the pile group acting as a unit.

The lesser of the two capacities should be used in design.

Drilled Shaft Lateral Loading

Recommended geotechnical parameters for lateral load analysis of drilled shaft foundations have been developed for use in the computer program L-PILE 2016 that utilizes P-y curve analyses, and they are presented in the following table:

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Soil Type

Depth to

Bottom of

Layer (ft)

Soil Type (P-y)

Curve Model

Total Unit

Weight

(pcf)

Friction

Angle

Φ’

Cohesion

(psf)

Soil Modulus

(pci)

Stratum 1 15 Sand (Reese) 110 30 ---

Allow L-Pile Program to Choose Values

Stratum 2 30 Sand (Reese) 115 33 ---

Stratum 3 45 Sand (Reese) 125 36 ---

Stratum 4 58 Sand (Reese) 125 38 ---

Lateral load design parameters are valid for maximum soil strain of five percent acting over a distance of one shaft or pile diameter.

Drilled Shaft Construction Considerations

Drilling of foundations to design depths up to 58 feet should be possible with conventional drilling equipment using single flight power augers.

Due to dry nature of the sandy soils, caving of the excavated shaft should be anticipated that may require the use of temporary casing during construction. Drilled shaft concrete should be placed soon after completion of drilling and cleaning. Due to potential sloughing and raveling, foundation concrete quantities may exceed calculated geometric volumes.

If casing is used for drilled shaft construction, it should be…