2011 FERL Geotechnical Report.pdf

Geotechnical Engineering Report Construct FERL Shower/Shave Facility

Project XQPZ 11-60543 United States Air Force Academy, Colorado

November 10, 2011 Project No. 23115034

Prepared for:

Farris Engineering Colorado Springs, Colorado

Prepared by:

Terracon Consultants, Inc.

Colorado Springs, Colorado

Terracon Consultants, Inc. 4172 Center Park Drive Colorado Springs, Colorado 80916

P [719] 597 2116 F [719] 597 2117 terracon.com

November 10, 2011

Farris Engineering 650 First Street Colorado Springs, Colorado

Attn: Mr. Jerry Pasley, Jr., P.E.

Re: Geotechnical Engineering Report

Construct FERL Shower/Shave Facility – Project XQPZ 11-60543 East of Parade Loop and FERL Road United States Air Force Academy, Colorado Terracon Project Number: 23115034

Terracon Consultants, Inc. (Terracon) has performed geotechnical engineering services for the above referenced project. This study was performed in general accordance with our proposal number D2311201 dated September 14, 2011. This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork and the design and construction of foundations and floor slabs 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.

Robert M. Hernandez, P.E. Ryan W. Feist, P.E.

Senior Staff Engineer Geotechnical Services Manager

Copies to: Addressee (3)

TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................................................................................ ii

1.0 INTRODUCTION

2.0 PROJECT INFORMATION

2.1 Project Description

2.2 Site Location and Description

3.0 SUBSURFACE CONDITIONS

3.1 General and Local Geology

3.2 Typical Profile

3.2 Groundwater

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

4.1 Geotechnical Considerations

4.2 Earthwork

4.2.1 Site Preparation

4.2.2 Material Types

4.2.3 Compaction Requirements

4.2.4 Grading and Drainage

4.2.5 Construction Considerations

4.3 Foundation Systems

4.3.1 Design Recommendations – Drilled Piers

4.3.2 Construction Considerations

4.3.3 Design Recommendations – Shallow Spread-Footing

4.3.4 Construction Considerations

4.4 Seismic Considerations

4.5 Floor Slab

4.5.1 Design Recommendations

4.5.2 Construction Considerations

4.6 Exterior Slabs

4.7 Corrosion Considerations

5.0 GENERAL COMMENTS

APPENDIX A – FIELD EXPLORATION

Exhibit A-1 Site Vicinity Diagram Exhibit A-2 Boring Location Plan Exhibit A-3 Field Exploration Description Borings B-1 to B-2 Boring Logs

APPENDIX B – LABORATORY TESTING

Exhibit B-1 Laboratory Testing Description Exhibit B-2 Atterberg Limits Exhibit B-3 Grain Size Distribution Exhibit B-4 to B-6 Consolidation Test Results Exhibit B-7 Corrosivity Test Results

APPENDIX C – SUPPORTING DOCUMENTS

Exhibit C-1 General Notes Exhibit C-2 Unified Soil Classification System

Shower/Shave Facility – Project XQPZ 11-60543 ■ USAFA, Colorado November 10, 2011 ■ Terracon Project No. 23115034

Reliable ■ Responsive ■ Resourceful ii

EXECUTIVE SUMMARY

A geotechnical investigation has been performed for the proposed FERL Shower/Shave Facility, to be located at east of Parade Loop and FERL Road at the United States Air Force Academy, Colorado. Two test borings were advanced to depths of approximately 24 to 39 feet below the existing ground surface within the general vicinity of the proposed building area. The following geotechnical considerations were identified:

The proposed building may be supported on either a drilled pier foundation system or a shallow spread footing foundation system. We recommend floor slabs bear on a minimum of 12 inches of scarified, water conditioned, and recompacted on-site sand soils.

Approximately 2 to 3 feet of fill was encountered at the site. Based on our subsurface exploration, the fill soils encountered have blow counts and in-situ densities generally similar to or greater than the native soils. Therefore, it is our opinion that the fill soils should perform similarly to the native soils. We recommend that Terracon perform field density testing and observations during construction.

On-site sand soils are considered suitable for reuse as engineered fill beneath foundations and slabs.

The 2009 International Building Code, Table 1613.5.2 IBC seismic site classification for this site is C.

Close monitoring of the construction operations discussed herein will be critical in achieving the design subgrade support. We therefore recommend that Terracon be retained to monitor this portion of the work.

This summary should be used in conjunction with the entire report for design purposes. It should be recognized that details were not included or fully developed in this section, and the report must be read in its entirety for a comprehensive understanding of the items contained herein. The section titled GENERAL COMMENTS should be read for an understanding of the report limitations.

Reliable ■ Responsive ■ Resourceful 1

GEOTECHNICAL ENGINEERING REPORT

CONSTRUCT FERL SHOWER/SHAVE FACILITY

PROJECT XQPZ 11-60543

UNITED STATES AIR FORCE ACADEMY, COLORADO

Project No. 23115034 November 10, 2011

1.0 INTRODUCTION

A geotechnical investigation has been performed for the proposed Shower/Shave Facility, to be located at east of Parade Loop and FERL Road at the United States Air Force Academy, Colorado.

Two test borings were advanced to depths of approximately 24 to 39 feet below the existing ground surface within the general vicinity of the proposed building area. Boring logs along with a Boring Location Plan are included in Appendix A of this report.

The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

subsurface soil and bedrock conditions floor slab design and construction groundwater conditions earthwork foundation design and construction drainage

2.0 PROJECT INFORMATION

2.1 Project Description

ITEM DESCRIPTION

Site layout See Appendix A, Boring Location Plan

Proposed Development

Based on information provided by Ferris Engineering and the Statement of Work for A-E Design Services, dated August 31, 2011, the proposed project consists of the construction of a single-story, shower/shave facility, occupying a footprint on the order of 3,600 square feet. The building is anticipated to be supported on a grade beam and drilled pier foundation system. The grade beam and deep foundations are planned to be used as part of a planned closed-loop geothermal system.

Building construction ICF bearing walls supporting roof trusses (reported)

Finished floor elevation We anticipate finished floor of the structure to be within one foot of existing grades

Maximum loads Drilled piers - 90 kips, unfactored (reported)

FERL Shower/Shave Facility – Project XQPZ 11-60543 ■ USAFA, Colorado

Reliable ■ Responsive ■ Resourceful 2

Anticipated foundations Drilled pier foundation system (reported)

Maximum allowable movement

Total: 1 inch (assumed) Differential: ½ to ¾ of total (assumed)

Grading Unknown. We anticipate cuts and fills up to two feet to achieve finished construction grades.

Cut and fill slopes Assumed to be no steeper than 4H:1V (Horizontal to Vertical)

Proposed free standing retaining walls Not reported as part of site development.

Below grade areas A basement is not planned for the proposed shower/shave facility.

2.2 Site Location and Description

Location The project site is located east of Parade Loop and FERL Road in Colorado Springs, Colorado.

Existing improvements

The area of the proposed shower/shave facility had been rough graded by others prior to our site exploration. Areas surrounding the proposed facility had been developed with the FERL engineering campus. The proposed facility was bordered to the north and west by existing single-story, wood-framed, cabin-type structures, and to the south and east by relatively undeveloped land followed by the remaining FERL engineering campus.

Current ground cover Gravel surfaced with a sparse amount of native weeds.

Existing topography The site was relatively flat to gently sloping downward to the north to northwest at an approximate 15:1 (horizontal:vertical) slope.

3.0 SUBSURFACE CONDITIONS

3.1 General and Local Geology

The project site is located within the Colorado Piedmont section of the Great Plains physiographic province. The Colorado Piedmont, formed during the Late Tertiary and Early Quaternary time (approximately two million years ago), is a broad, erosional trench which separates the Southern Rocky Mountains from the High Plains. Structurally the site lies along the western flank of the Denver Basin. During the Late Mesozoic and Early Cenozoic periods (approximately 70 million years ago), intense tectonic activity occurred, causing the uplifting of the Front Range and associated downwarping of the Denver Basin to the east. Relatively flat uplands and broad valleys characterize the present-day topography of the Colorado Piedmont in this region.

Reliable ■ Responsive ■ Resourceful 3

Surficial geologic conditions at the site as mapped by the United States Geological Survey (USGS) (Scott, Varnes, Orkild, Colton, Rozanskid, 1954 and 19591) indicate the site is overlain by Colluvium of recent age, Lehman Ridge Gravel of Pleistocene age, and the Dawson Formation of the upper Cretaceous age. Colluvium deposits are described as detritus that moved or was deposited mainly by the action of gravity or rill wash rather than by streams. The deposits are mainly reddish-brown, coarse grained sand, pebbles, and some boulders.

The Lehman Ridge Gravel is the highest pediment in the Academy area and is composed of reddish brown fragments of Pikes Peak Granit ranging in size from silt to boulders 20 feet in diameter. Pebbles of quarts and feldspar ¼ to 1-inch in diameter make up a bulk of the gravel.

The Dawson Formation is described as light-gray coarse sandstone that contains hard sandy ironstone layers that cap monumentlike erosion remnants. Crossbedding and cut-and-fill channel deposits are characteristic of sandstone parts.

3.2 Typical Profile

Subsurface conditions on the project site can be generalized as shown on the following page:

Description Approximate Depth to Bottom of Stratum Material Encountered Consistency/Density

Stratum 1 2 to 3 feet Fill materials comprised of sand with varying amounts of silt and gravel.

Very dense

Stratum 2 6 to 9 feet Similar native sands, silt, and gravel Very dense

Stratum 3 24 to 39 feet Sandstone Hard to very hard

Conditions encountered at each boring location are indicated on the individual boring logs.

Stratification boundaries on the boring logs represent the approximate location of changes in soil and bedrock types; in-situ, the transition between materials may be gradual. Details for each of the borings can be found on the boring logs in Appendix A of this report.

Laboratory test results indicate that the sand soils tested at shallow depths exhibit low compression at in-situ water contents. When elevated in water content, the materials tested exhibit non-expansive potential and low to moderate compression at increased loading.

1Scott, G.R., Varnes, D.J., Orkild, P.P., Colton, R.B., Rozanski, George, 1954 and 1959, Geologic Map of the United States Air Force Academy, El Paso County, Colorado, United States Geological Survey, Department of Interior, Professional Paper 551, Plate 1.

Reliable ■ Responsive ■ Resourceful 4

Based on the relatively high blow counts, relatively low water content, and the granular nature of the soil, the moderate compression observed in the sample tested from Boring B-2 at 5 feet may be the result of disturbance during field sampling or laboratory preparation. Subsequently, results have been included in this report, but are not considered representative of the in-situ soils.

3.2 Groundwater

Groundwater was not encountered at the time of field exploration. 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 levels can be expected to fluctuate with varying seasonal and weather conditions.

Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater levels during construction or at other times in the life of the structure may be higher or lower than the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project.

Fluctuations in groundwater levels can best be determined by implementation of a groundwater monitoring plan. Such a plan would include installation of groundwater monitoring wells and periodic measurement of groundwater levels over a sufficient period of time.

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

4.1 Geotechnical Considerations

Based on the results of our field investigation, laboratory testing program and geotechnical analyses, development of the site is considered feasible from a geotechnical viewpoint provided that the conclusions and considerations provided herein are incorporated into the design and construction of the project.

Approximately 2 to 3 feet of fill was encountered at the site. Based on our subsurface exploration, the fill soils encountered have blow counts and in-situ densities generally similar to or greater than the native soils. Therefore, it is our opinion that the fill soils should perform similarly to the native soils. We recommend that Terracon perform field density testing and observations during construction.

It is our understanding that the proposed shower/shave facility will be supported on a drilled pier foundation system with a vertical thermal loop field installed within the drilled pier and grade beam foundations. It is our opinion that a drilled pier foundation system is considered suitable for support of the structure. It is also our opinion that shallow spread-footings may be

Reliable ■ Responsive ■ Resourceful 5 considered suitable for support of the building. We have included parameters for both foundation systems to provide options during the design phase.

Design and construction recommendations for foundation systems and other earth connected phases of the project are outlined below.

4.2 Earthwork

4.2.1 Site Preparation

Prior to placing any fill, all vegetation and any otherwise unsuitable material should be removed from the proposed floor slab and foundation areas. The subgrade should be proof-rolled where possible or probed with a metal T-probe to aid in locating loose, soft, or otherwise undesirable areas. Proof-rolling can be performed with a loaded tandem axle dump truck. Unacceptable soil should be removed or mitigated in place prior to placing fill.

Although evidence of underground facilities was not observed during the site reconnaissance, such features could be encountered during construction. If unexpected underground facilities are encountered, such features should be removed and the excavation benched to expose firm, approved materials prior to backfill placement and/or construction.

4.2.2 Material Types

Engineered fill should meet the following material property requirements:

Fill Type 1 USCS Classification Acceptable Location for Placement

On-Site Sand Soils SP-SM The on-site sand soils are considered acceptable for use as engineered fill beneath foundations and slabs.

Imported Soils Varies Imported soils meeting the gradation outlined herein can be considered acceptable for use as engineered fill beneath foundations and slabs.

1. Controlled, compacted fill should consist of approved materials that are free of organic matter and debris. Frozen material should not be used, and fill should not be placed on a frozen subgrade. A sample of each material type should be submitted to the geotechnical engineer for evaluation.

Reliable ■ Responsive ■ Resourceful 6

Imported soils (if required) should conform to the following:

Gradation Percent finer by weight (ASTM C136) 3” 100

No. 4 Sieve 50-100 No. 200 Sieve 35 (max)

Liquid Limit……………………………………………………NP Plastic Limit…………………………………………………..NP

4.2.3 Compaction Requirements

Fill Lift Thickness

8-inches or less in loose thickness when heavy, self-propelled compaction equipment is used 4 to 6 inches in loose thickness when hand-guided equipment (i.e.

jumping jack, plate compactor) is used

Compaction Requirements 1 92% of the materials maximum dry density (ASTM D1557) for foundations and slabs

Water Content 2 Within three percent of optimum water content

1. We recommend that engineered fill be tested for water content and compaction during placement.

Should the results of the in-place density tests indicate the specified water or compaction limits have not been met, the area represented by the test should be reworked and retested as required until the specified water and compaction requirements are achieved.

2. Specifically, water levels should be maintained low enough to allow for satisfactory compaction to be achieved without the compacted fill material pumping when proofrolled.

4.2.4 Grading and Drainage

All grades must be adjusted to provide positive drainage away from the structure during construction and maintained throughout the life of the proposed project. Infiltration of water into utility or foundation excavations must be prevented during construction. Landscaped irrigation adjacent to foundation systems should be minimized or eliminated. Water permitted to pond near or adjacent to the perimeter of the structures (either during or post-construction) can result in significantly higher soil movements than those discussed in this report. As a result, any estimations of potential movement described in this report cannot be relied upon if positive drainage is not obtained and maintained, and water is allowed to infiltrate the fill and/or subgrade. Exposed ground should be sloped at a minimum of 10 percent grade for at least 10 feet beyond the perimeter of the building, where possible. Where possible, asphalt pavement or concrete flatwork should be sloped at a minimum of 2 percent beyond the building perimeter, where possible. Where ADA or other requirements or existing site features limit the gradient, slopes on the order of ½ to 1 percent minimum are considered acceptable. Backfill against

Reliable ■ Responsive ■ Resourceful 7 footings, exterior walls and in utility line trenches should be well compacted and free of all construction debris to reduce the possibility of water infiltration. After building construction and prior to project completion, we recommend that verification of final grading be performed to document that positive drainage, as described above, has been achieved.

Where paving or flatwork abuts the structure, care should be taken that joints are properly sealed and maintained to prevent the infiltration of surface water. Consideration should be given to snow removal practices that will minimize the stockpiling of snow adjacent to structural improvements.

Roof drains should discharge on pavements or be extended away from the structure a minimum of 5 feet through the use of splash blocks or downspout extensions. A preferred alternative is to have the roof drains discharge to storm sewers by solid pipe or other appropriate outfall.

4.2.5 Construction Considerations

Although the exposed subgrade is anticipated to be relatively stable upon initial exposure, unstable subgrade conditions could develop during general construction operations, particularly if the soils are wetted and/or subjected to repetitive construction traffic. Should unstable subgrade conditions develop, stabilization measures will need to be employed. Options for subgrade stabilization can include removal of unsuitable material and replacement with approved fill material. An alternative can include the use of geogrid overlain by CDOT Class 5 or 6 aggregate base course. The depth of aggregate base course will depend on the severity of unstable soils.

Upon completion of filling and grading, care should be taken to maintain the subgrade moisture content prior to construction of floor slabs and pavements. Construction traffic over the completed subgrade should be avoided to the extent practical. The site should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. If the subgrade should become frozen, desiccated, saturated, or disturbed, the affected material should be removed or these materials should be scarified, moisture conditioned, and recompacted prior to floor slab and pavement construction.

As a minimum, all temporary excavations should be sloped or braced as required by Occupational Health and Safety Administration (OSHA) regulations to provide stability and safe working conditions. Temporary excavations will probably be required during grading operations.

The grading contractor, by his contract, is usually 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. All excavations should comply with applicable local, state and federal safety regulations, including the current OSHA Excavation and Trench Safety Standards.

Reliable ■ Responsive ■ Resourceful 8

4.3 Foundation Systems

4.3.1 Design Recommendations – Drilled Piers

For this project, we recommend the following:

DESCRIPTION STRAIGHT SHAFT PIERS

Minimum frost depth from grade beams 30 inches

Minimum embedment into bedrock 5 feet*

Minimum pier diameter 12 inches

Pier concrete slump (uncased piers) 5 to 7 inches

Pier concrete slump (cased piers) 7 to 9 inches

Approximate total movement 1 ½ inch

1. The foundation movement will depend upon the variations within the subsurface soil profile, the structural loading conditions, the quality of the earthwork operations, and maintaining uniform soil water content throughout the life of the structure. The estimated movements are based on maintaining uniform soil water content during the life of the structure. Additional foundation movements could occur if water from any source infiltrates the foundation soils; therefore, proper drainage and irrigation practices should be incorporated into the design and operation of the facility.

Failure to maintain soil water content and positive drainage will nullify the movement estimates provided above.

*Anticipate minimum 14-foot long piers from existing ground surface.

A summary of the drilled pier foundation design recommendations is shown on the following page. The maximum end bearing pressures given in the table are based on the cross-sectional area of the tip of the drilled shaft. Skin friction (Sd) should be applied to the surface area of the drilled shaft for that given length interval below a depth of 30 inches. The combination of skin friction and end bearing pressure can be used to determine the vertical compression capacity.

The skin friction value should be used to determine the uplift capacity of the soil. For lateral load and overturning design, we have included beam on elastic foundation spring constants, lateral equivalent earth pressures, and more commonly used LPILE parameters. For calculation of lateral deflection using the beam on elastic foundation method, a coefficient of subgrade reaction listed on the table may be used for the analysis. Lateral load design parameters are valid for maximum soil strain of 1 percent for the native soils and ½ percent for bedrock acting over a distance of one shaft diameter. The passive pressure, coefficient of horizontal subgrade reaction, and LPILE parameters are ultimate values; therefore, appropriate factors of safety should be applied in the pier design.

All shafts should be reinforced full-depth for the applied axial, lateral and uplift stresses imposed. Provided that the drilled shaft is loaded to full axial capacity, minimum reinforcement of at least one percent of the cross-sectional area of the pier should be specified. Where the

Reliable ■ Responsive ■ Resourceful 9 loading of drilled shaft foundations falls below the full axial capacity, reinforcement may be reduced to that necessary to satisfy other structural engineering requirements of the design.

DESCRIPTION

MATERIAL TYPE AND DEPTH, FEET

Poorly Graded Sand

2½ to 9 feet

Sandstone Bedrock

9 to 39 feet

Allowable Vertical Parameters:

Bearing

Skin friction

3,5001 psf

20 psf/ft

35,0002 psf

2,000 psf

Ultimate Lateral Parameters

Beam on Elastic Foundation:

Passive, EFP,psf/ft

Soil Code 4 3

Unit Weight (pci) 0.069 0.072

Su (psi) N/A 115

Angle of internal Friction, (degrees) 32 N/A

Horizontal Modulus of Subgrade Reaction:

k (static) pci k (cyclic) pci

2,000

Strain at 50% of Maximum Stress, 50 N/A 0.004

1 Bearing capacity for shallow, spread footing foundations.

2 Minimum 5-foot embedment into bedrock.

It should be noted that the provided lateral parameters design values do not include a factor-of-safety, which should be applied. We recommend neglecting skin friction and lateral resistance for the upper 30 inches of drilled piers because of the effects of frost penetration.

The capacity of individual piers must be reduced when considering the effects of group action.

Capacity reduction is a function of pier spacing and the number of piers within a group. If group action analyses are necessary, capacity reduction factors can be provided for the analyses

Reliable ■ Responsive ■ Resourceful 10

4.3.2 Construction Considerations

Drilling to design depths may be possible with double-flight power augers equipped with rock teeth. We anticipate the need for specialized rock drilling as difficult drilling conditions will be encountered due to the presence of very hard bedrock. Shafts should remain open without stabilizing measures; however, temporary casing may be required due to the potential for caving. Pier concrete should be placed immediately after completion of drilling and cleaning.

Due to potential sloughing and raveling, foundation concrete quantities may exceed calculated geometric volumes.

If concrete cannot be placed in dry conditions, a tremie or casing should be used for concrete placement. If casing is used for pier construction, it should be withdrawn in a slow, continuous manner maintaining a sufficient head of concrete to prevent infiltration of water or the creation of voids in pier concrete. Pier concrete should have a relatively high fluidity when placed in cased pier holes or through a tremie.

Free-fall concrete placement in piers will only be acceptable if provisions are taken to avoid striking the concrete on the sides of the hole or reinforcing steel and there is no water at the bottom of the pier excavation. The use of a bottom-dump hopper, or an elephant's trunk discharging near the bottom of the hole where concrete segregation will be minimized, is recommended. Shaft bearing surfaces must be free of loose materials prior to concrete placement.

4.3.3 Design Recommendations – Shallow Spread-Footing

As an alternative, spread footing foundations are also considered suitable for support of the proposed shower/shave facility. If selected, we recommend spread footing foundations bear on a minimum of 12 inches of scarified, water conditioned, and re-compacted on-site soils.

Additional design recommendations are presented below and on the following pages:

DESCRIPTION Column Wall Net allowable bearing pressure 1 3,500 psf 3,500 psf

Minimum dimensions 24 inches 16 inches

Minimum amount of compacted fill beneath footings 12 inches 12 inches

Minimum embedment below finished grade for frost protection 2 30 inches 30 inches

Approximate total movement 3 1 inch 1 inch

Estimated differential movement 3 ½ to ¾ of total between columns

½ to ¾ of total over 40 feet

1. The recommended net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation. Assumes fill or unsuitable soils, if

Reliable ■ Responsive ■ Resourceful 11 encountered, will be undercut and replaced with engineered fill.

2. For exterior foundations beneath continuously heated structures, depth below the lowest adjacent exterior grade within 5 horizontal feet of the structure. The minimum depth for interior footings in continuously heated structures is 12 inches below finished grade.

3. The foundation movement will depend upon the variations within the subsurface soil profile, the structural loading conditions, the embedment depth of the footings, the thickness of compacted fill, the quality of the earthwork operations, and maintaining uniform soil water content throughout the life of the structure. The estimated movements are based on maintaining uniform soil water content during the life of the structure. Additional foundation movements could occur if water from any source infiltrates the foundation soils; therefore, proper drainage and irrigation practices should be incorporated into the design and operation of the facility. Failure to maintain soil water content and positive drainage will nullify the movement estimates provided above.

4.3.4 Construction Considerations

The base of all foundation excavations should be free of water and loose soil and rock prior to placing concrete. If unsuitable soils are encountered at the base of the over-excavation, supplemental recommendations will be required, such as additional removal and replacement.

Over-excavation for compacted backfill placement below footings should extend laterally beyond all edges of the footings at least 8 inches per foot of overexcavation depth below footing base elevation.

Fill should be placed in lifts of 8 inches or less in loose thickness and compacted to at least 92 percent of the material's maximum dry density (ASTM D1557). Compactive effort should be in accordance with recommendations provided in the EARTHWORK section of this report.

Concrete should be placed soon after excavating to reduce bearing soil disturbance.

Should the soils at bearing level become excessively dry, disturbed or saturated, or frozen, the affected soil should be removed prior to placing concrete. It is recommended that a construction testing laboratory be retained to observe and test the soil foundation bearing materials.

4.4 Seismic Considerations

Code Used Site Classification

2009 International Building Code (IBC) 1 C2

Mapped Spectral Acceleration for

Short Periods, Ss 2 0.219

Reliable ■ Responsive ■ Resourceful 12

Mapped Spectral Acceleration for a 1-second period, S1 2

0.059

1. In general accordance with the 2009 International Building Code, Table 1613.5.2. The 2009 International Building Code (IBC) requires a site soil profile determination extending a depth of 100 feet for seismic site classification. The current scope requested does not include the required 100 foot soil profile determination as borings for this project extended to a maximum depth of approximately 39 feet. Additional exploration to deeper depths could be performed to confirm the conditions below the current depth of exploration. Alternatively, a geophysical exploration could be utilized in order to attempt to justify a higher seismic site class.

2. USGS Seismic Hazard Curves, Response Parameters and Design Parameters

4.5 Floor Slab

4.5.1 Design Recommendations

Floor slab support1

We recommend building floor slabs be supported on a minimum of 12 inches of scarified, water conditioned, and recompacted on-site soils. We recommend the exposed subgrade be proof rolled prior to slab construction. Soft or unsuitable subgrade should be removed and replaced with approved, compacted fill.

1. We recommend subgrades be maintained in a relatively moist condition until floor slabs are constructed. If the subgrade should become desiccated prior to construction of floor slabs, the affected material should be removed or the materials scarified, moistened, and recompacted.

Upon completion of grading operations in the building areas, care should be taken to maintain the recommended subgrade moisture content and density prior to construction of the building floor slabs.

Where appropriate, saw-cut control joints should be placed in the slab to help control the location and extent of cracking. The use of a vapor retarder should be used directly beneath concrete slabs on grade that will be covered with wood, tile, carpet or other moisture sensitive or impervious coverings, or when the slab will support equipment sensitive to moisture. When conditions warrant the use of a vapor retarder, the slab designer should refer to ACI 302 and/or ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder.

4.5.2 Construction Considerations

We recommend the area underlying the floor slab be rough graded and then thoroughly proofrolled with a loaded tandem axle dump truck prior to final grading. Particular attention should be paid to high traffic areas that were rutted and disturbed earlier, areas where backfilled trenches are located, as well as the backfill zone adjacent to the existing structure. Areas where unsuitable conditions are located should be repaired by removing and replacing the affected material with properly compacted fill. All floor slab subgrade areas should be moisture conditioned and

Reliable ■ Responsive ■ Resourceful 13 properly compacted to the recommendations in this report immediately prior to placement of the base rock and concrete.

4.6 Exterior Slabs

Exterior slabs-on-grade, exterior architectural features, and utilities founded in backfill may experience some movement due to the volume change of the material. Additional recommendations to reduce potential movement are as follows:

■ minimizing moisture increases in the backfill

■ controlling moisture-density during placement of backfill

■ using designs which allow vertical movement between the exterior features and adjoining structural elements

■ placing effective control joints on relatively close centers

4.7 Corrosion Considerations

The following table lists the results of laboratory soluble sulfate, soluble chloride, electrical resistivity, and pH testing. These 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.

Boring Soluble Sulfate (Percent)

Soluble Chloride (Percent)

Electrical Resistivity (ohm.cm) pH

B-1 0.002 0.0004 4,237 8.1

Results of soluble sulfate testing indicate that samples of the on-site soils tested posses negligible sulfate concentrations when classified in accordance with Table 4.3.1 of the ACI Design Manual. Concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4.

5.0 GENERAL COMMENTS

Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, across the site, or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after

Reliable ■ Responsive ■ Resourceful 14 construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided.

The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing.

APPENDIX A

FIELD EXPLORATION

Reliable ■ Responsive ■ Resourceful Exhibit A-2

Field Exploration Description

Two test borings were advanced in the vicinity of the proposed building area on October 27, 2011 to depths of approximately 24 to 39 feet below existing site grade at the approximate locations shown on the Boring Location Plan, Exhibit A-1. The borings were advanced with a truck-mounted drilling rig, utilizing 4-inch diameter solid-stem auger.

The borings were located in the field by referencing property lines and existing site features. The accuracy of the boring locations should only be assumed to the level implied by the methods used.

Lithologic logs of the borings were recorded by the Terracon field representative during drilling operations. At selected intervals, samples of the subsurface materials were taken by driving split-spoon and ring barrel samplers. Representative bulk samples of subsurface materials were also obtained.

Penetration resistance measurements were obtained by driving the split-spoon and ring barrel samplers into the subsurface materials with a 140-pound hammer falling 30 inches. The penetration resistance value is a useful index to the consistency, relative density or hardness of the materials encountered.

An automatic SPT hammer was used to advance the samplers in the borings. A greater efficiency is typically achieved with the automatic hammer compared to the conventional safety hammer operated with a cathead and rope. Published correlations between the barrel blow counts, SPT values, and soil properties are based on the lower efficiency cathead and rope method. This higher efficiency affects the standard penetration resistance blow count value by increasing the penetration per hammer blow over what would be obtained using the cathead and rope method. The effect of the automatic hammer's efficiency has been considered in the interpretation and analysis of the subsurface information for this report.

Groundwater measurements were made in the borings at the time of site exploration. Borings were backfilled with auger cuttings prior to leaving the site. Some settlement of the backfill should be anticipated.

FILL-POORLY GRADED SAND, with silt and gravel; brown to reddish brown, fine to coarse grained, very dense.

POORLY GRADED SAND, with silt and gravel; brown to reddish brown, fine to coarse grained, very dense.

SILTY SANDSTONE; brown to reddish brown, fine grained, hard to very hard.

BOTTOM OF BORING

-200 = 25

LL = NV

PI = NP

BS

RS

SS

RS

RS

SS

RS

RS

SS

SS

SS

SS

SS

SP

SM

SP

SM

SP

SM

50/6"

50/6"

50/6"

50/6"

50/3"

50/3"

50/1"

50/1"

50/1"

50/3"

0.5

0.5

10-27-11BORING STARTED

WD ABNone

SITE

CLIENT

WL

WL

APPROVED

The stratification lines represent the approximate boundary lines

U N

C O

N F

IN

E

D S

T R

E N

G T

H , p sf

TESTS

10-27-11

DESCRIPTION

WATER LEVEL OBSERVATIONS, ft

Farris Engineering

23115034

CME-55

RWF PROJ. NO.

LOGGED

PROJECT

BORING COMPLETED

* 140lb. SPT automatic hammer 4" diameter solid stem auger

None

RIG LKC

Approx. Surface Elevation: 6999 ft between soil and rock types: in-situ, the transition may be gradual.

Shower/Shave Facility East of Parade Loop and FERL Drive

United States Air Force Academy, Colorado

G R

A P

H

IC

L O

G

BORING LOG NO. B-1

P E

R C

E N

T F

IN

E

S A

T T

E R

B E

R G

LI

M

IT

S

B O

R E

H O

LE

W

IT

H

A T

T E

R B

E R

G L

IM

IT

S

4.

G

P J

D E

N V

E R

T E

M P

LA

T

E

-5 -1

1.

G

D T

1/

/1

T Y

P E

N U

M B

E R

D E

P T

H , f t.

SAMPLES

U S

C S

S Y

M B

O L

B

LO

W S ft.

R E

C O

V E

R Y

, i n.

W A

T E

R C

O N

T E

N T

D R

Y U

N

IT

W T

, p cf

FILL-POORLY GRADED SAND, with silt;

brown to reddish brown, fine to coarse grained, trace gravel.

POORLY GRADED SAND, with silt; brown to reddish brown, fine to coarse grained, dense to very dense, trace gravel.

SILTY SANDSTONE; brown to reddish brown, fine grained, very hard.

BOTTOM OF BORING

-200 = 11

LL = NV

PI = NP

BS

RS

SS

RS

RS

SS

RS

RS

SS

SS

SP

SM

SP

SM

SP

SM

50/5"

50/9"

50/5" 87/10"

50/2"

50/1"

50/6"

50/1"

10-27-11BORING STARTED

WD ABNone

SITE

CLIENT

WL

WL

APPROVED

The stratification lines represent the approximate boundary lines

U N

C O

N F

IN

E

D S

T R

E N

G T

H , p sf

TESTS

10-27-11

DESCRIPTION

WATER LEVEL OBSERVATIONS, ft

Farris Engineering

23115034

CME-55

RWF PROJ. NO.

LOGGED

PROJECT

BORING COMPLETED

* 140lb. SPT automatic hammer 4" diameter solid stem auger

None

RIG LKC

Approx. Surface Elevation: 7000 ft between soil and rock types: in-situ, the transition may be gradual.

Shower/Shave Facility East of Parade Loop and FERL Drive

United States Air Force Academy, Colorado

G R

A P

H

IC

L O

G

BORING LOG NO. B-2

P E

R C

E N

T F

IN

E

S A

T T

E R

B E

R G

LI

M

IT

S

B O

R E

H O

LE

W

IT

H

A T

T E

R B

E R

G L

IM

IT

S

4.

G

P J

D E

N V

E R

T E

M P

LA

T

E

-5 -1

1.

G

D T

1/

/1

T Y

P E

N U

M B

E R

D E

P T

H , f t.

SAMPLES

U S

C S

S Y

M B

O L

B

LO

W S ft.

R E

C O

V E

R Y

, i n.

W A

T E

R C

O N

T E

N T

D R

Y U

N

IT

W T

, p cf

APPENDIX B

LABORATORY TESTING

Reliable ■ Responsive ■ Resourceful Exhibit B-1

Laboratory Testing

Samples retrieved during the field exploration were returned to the laboratory for observation by the project geotechnical engineer. An applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials. The field descriptions were confirmed or modified as necessary, and were classified in general accordance with the Unified Soil Classification System described in Appendix C. Samples of bedrock were classified in general accordance with the general notes for Rock Classification.

Laboratory test results are presented on the Logs of Borings and in Appendix B, and were used for the geotechnical engineering analyses, and the development of foundation and earthwork recommendations. Laboratory tests were performed in general accordance with the applicable Terracon test standards.

Selected soil and/or bedrock samples were tested for the following engineering properties:

■ Water content

■ Dry density

■ Consolidation/expansion

■ Grain size

■ Plasticity index

■ Electrical resistivity

■ pH

■ Water soluble sulfate content

■ Water soluble chloride content

0.0010.010.1110100

SAND

SILT OR CLAY

LL PL

D10 fine

6 61 3/4 1/23/8

CuPI Cc

17.86

0.0

11.2

4 143 2 8

COBBLES

GRAVEL

NP

NP

GRAIN SIZE DISTRIBUTION

24.6

11.0

75.4

77.8

B-1

B-2

9.5

6050 100

0.70 coarse

1.5

GRAIN SIZE IN MILLIMETERS

P E

R C

E N

T F

IN

E

R B

Y W

E

IG

H T

Classification coarse

D100Specimen Identification

NP

NP

0.183

1.222

D30

16 20 30 40

U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS

SILTY SAND(SM)

POORLY GRADED SAND with SILT(SP-SM) fine

%Gravel %Sand %Silt

Specimen Identification

%Clay

Date: 11-02-11

0.088

0.242

HYDROMETER

B-1

B-2

D60 medium

7.0ft

2.0ft

7.0 ft

2.0 ft

NP

NP

Project: Shower/Shave Facility

Proj. No. 23115034 Site: East of Parade Loop and FERL Drive, United States Air Force Academy, Colorado

T C

_G R

A

IN

_S

IZ

E

.G P

J D

E N

V E

R

0.

G

D T

1/

/1

-6

-5

-4

-3

-2

-1

100 1,000 10,000

A X

IA

L

S T

R A

IN

PRESSURE, psf

SWELL CONSOLIDATION TEST

Date: 11-02-11

Project: Shower/Shave Facility

Proj. No. 23115034 Site: East of Parade Loop and FERL Drive, United States Air Force Academy, Colorado

, pcf WC,%

112 7POORLY GRADED SAND with SILT(SP-SM)B-1 2.0 ft

ClassificationSpecimen Identification

Notes: Water was added at 500 pounds per square foot (psf).

T C

_C O

N S

O L_

S T

R A

IN

4.

G

P J

D E

N V

E R

0.

G D

T

1/

-6

-5

-4

-3

-2

-1

100 1,000 10,000

A X

IA

L

S T

R A

IN

PRESSURE, psf

SWELL CONSOLIDATION TEST

Date: 11-02-11

Project: Shower/Shave Facility

Proj. No. 23115034 Site: East of Parade Loop and FERL Drive, United States Air Force Academy, Colorado

, pcf WC,%

124 5POORLY GRADED SAND with SILT(SP-SM)B-2 5.0 ft

ClassificationSpecimen Identification

Notes: Disturbed sample. Water was added at 500 pounds per square foot (psf).

T C

_C O

N S

O L_

S T

R A

IN

4.

G

P J

D E

N V

E R

0.

G D

T

1/

APPENDIX C

SUPPORTING DOCUMENTS

GENERAL NOTES

DRILLING & SAMPLING SYMBOLS:

SS: Split Spoon – 1-3/8" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger ST: Thin-Walled Tube - 2" O.D., unless otherwise noted PA: Power Auger RS: Ring Sampler - 2.42" I.D., 3" O.D., unless otherwise noted HA: Hand Auger DB: Diamond Bit Coring - 4", N, B RB: Rock Bit BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary

The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SS) the last 12 inches of the total 18-inch penetration with a 140-pound hammer falling 30 inches is considered the “Standard Penetration” or “N-value”.

WATER LEVEL MEASUREMENT SYMBOLS:

WL: Water Level WS: While Sampling N/E: Not Encountered WCI: Wet Cave in WD: While Drilling DCI: Dry Cave in BCR: Before Casing Removal AB: After Boring ACR: After Casing Removal

Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater.

In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations.

DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand.

Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.

CONSISTENCY OF FINE-GRAINED SOILS RELATIVE DENSITY OF COARSE-GRAINED SOILS

Unconfined

Compressive Strength, Qu, psf

Standard Penetration or N-value (SS)

Blows/Ft.

Consistency

Standard Penetration or N-value (SS)

Blows/Ft.

Ring Sampler (RS)

Blows/Ft. Relative Density

< 500 <2 Very Soft 0 – 3 0-6 Very Loose 500 – 1,000 2-3 Soft 4 – 9 7-18 Loose

1,001 – 2,000 4-6 Medium Stiff 10 – 29 19-58 Medium Dense 2,001 – 4,000 7-12 Stiff 30 – 49 59-98 Dense 4,001 – 8,000 13-26 Very Stiff 50+ 99+ Very Dense

8,000+ 26+ Hard

RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY

Descriptive Term(s) of other Constituents

Percent of Dry Weight

Major Component of Sample

Particle Size

Trace < 15 Boulders Over 12 in. (300mm) With 15 – 29 Cobbles 12 in. to 3 in. (300mm to 75 mm)

Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm)

Sand

Silt or Clay #4 to #200 sieve (4.75mm to 0.075mm)

Passing #200 Sieve (0.075mm)

RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION

Descriptive Term(s) of other

Constituents Percent of Dry Weight Term Plasticity

Index Trace < 5 Non-plastic 0 With 5 – 12 Low 1-10

Modifiers > 12 Medium 11-30 High 30+

UNIFIED SOIL CLASSIFICATION SYSTEM

Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Soil Classification

Group Symbol Group Name B

Coarse Grained Soils:

More than 50% retained on No. 200 sieve

Gravels:

More than 50% of coarse fraction retained on No. 4 sieve

Clean Gravels:

Less than 5% fines C

Cu 4 and 1 Cc 3 E GW Well-graded gravel F Cu 4 and/or 1 Cc 3 E GP Poorly graded gravel F

Gravels with Fines:

More than 12% fines C

Fines classify as ML or MH GM Silty gravel F,G, H Fines classify as CL or CH GC Clayey gravel F,G,H

Sands:

50% or more of coarse fraction passes No. 4 sieve

Clean Sands:

Less than 5% fines D

Cu 6 and 1 Cc 3 E SW Well-graded sand I Cu 6 and/or 1 Cc 3 E SP Poorly graded sand I

Sands with Fines:

More than 12% fines D

Fines classify as ML or MH SM Silty sand G,H,I Fines Classify as CL or CH SC Clayey sand G,H,I

Fine-Grained Soils:

50% or more passes the No. 200 sieve

Silts and Clays:

Liquid limit less than 50

Inorganic:

PI 7 and plots on or above “A” line J CL Lean clay K,L,M PI 4 or plots below “A” line J ML Silt K,L,M

Organic:

Liquid limit - oven dried

0.75 OL

Organic clay K,L,M,N

Liquid limit - not dried Organic silt K,L,M,O

Silts and Clays:

Liquid limit 50 or more

Inorganic:

PI plots on or above “A” line CH Fat clay K,L,M PI plots below “A” line MH Elastic Silt K,L,M

Organic:

Liquid limit - oven dried

0.75 OH

Organic clay K,L,M,P

Liquid limit - not dried Organic silt K,L,M,Q Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat

A Based on the material passing the 3-in. (75-mm) sieve B If field sample contained cobbles or boulders, or both, add “with cobbles or boulders, or both” to group name.

C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay.

D Sands with 5 to 12% fines require dual symbols: SW-SM well-graded sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay

E Cu = D60/D10 Cc =

DxD

)(D

F If soil contains 15% sand, add “with sand” to group name.

G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.

H If fines are organic, add “with organic fines” to group name.

I If soil contains 15% gravel, add “with gravel” to group name.

J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.

K If soil contains 15 to 29% plus No. 200, add “with sand” or “with gravel,” whichever is predominant.

L If soil contains 30% plus No. 200 predominantly sand, add “sandy” to group name.

M If soil contains 30% plus No. 200, predominantly gravel, add

“gravelly” to group name.

N PI 4 and plots on or above “A” line.

O PI 4 or plots below “A” line.

P PI plots on or above “A” line.

Q PI plots below “A” line.

GENERAL NOTES

Description of Rock Properties

WEATHERING

Fresh Rock fresh, crystals bright, few joints may show slight staining. Rock rings under hammer if crystalline.

Very…